WO2023232438A1 - Drum brake for a motor vehicle - Google Patents

Drum brake for a motor vehicle Download PDF

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Publication number
WO2023232438A1
WO2023232438A1 PCT/EP2023/062846 EP2023062846W WO2023232438A1 WO 2023232438 A1 WO2023232438 A1 WO 2023232438A1 EP 2023062846 W EP2023062846 W EP 2023062846W WO 2023232438 A1 WO2023232438 A1 WO 2023232438A1
Authority
WO
WIPO (PCT)
Prior art keywords
drum
jaw
brake
jaws
lever
Prior art date
Application number
PCT/EP2023/062846
Other languages
French (fr)
Inventor
Philippe Bourlon
Original Assignee
Hitachi Astemo France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Astemo France filed Critical Hitachi Astemo France
Publication of WO2023232438A1 publication Critical patent/WO2023232438A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/38—Slack adjusters
    • F16D65/40—Slack adjusters mechanical
    • F16D65/52—Slack adjusters mechanical self-acting in one direction for adjusting excessive play
    • F16D65/54—Slack adjusters mechanical self-acting in one direction for adjusting excessive play by means of direct linear adjustment
    • F16D65/546—Slack adjusters mechanical self-acting in one direction for adjusting excessive play by means of direct linear adjustment for mounting within the confines of a drum brake
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/02—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with mechanical assistance or drive
    • B60T13/04—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with mechanical assistance or drive by spring or weight
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
    • F16D51/16—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis
    • F16D51/18—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes
    • F16D51/20—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes extending in opposite directions from their pivots
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2121/00—Type of actuator operation force
    • F16D2121/02—Fluid pressure
    • F16D2121/04—Fluid pressure acting on a piston-type actuator, e.g. for liquid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2121/00—Type of actuator operation force
    • F16D2121/14—Mechanical

Definitions

  • the invention relates to the field of drum brakes for motor vehicles, more particularly to electromechanical type drum brakes used as a parking brake.
  • a drum brake for a motor vehicle generally comprises mechanical means for applying the brake or friction means, formed by jaw linings carried by jaws connected to an actuator capable of moving these friction means in the direction of a drum of brake linked in rotation to a wheel of the vehicle in order to brake the vehicle by friction, or move them away from the drum in order to stop braking.
  • the actuator moves the friction means towards the drum and holds them in this position as long as parking braking is desired.
  • the application of the parking brake typically takes place after having used the vehicle for a certain period of time, in order to park it.
  • the temperature of the drum is relatively high due to the braking which took place previously during use of the vehicle.
  • the drum is therefore in a relatively expanded state because of this high temperature and it is therefore necessary to separate the jaws carrying the linings accordingly to obtain a given clamping force allowing the vehicle to be immobilized.
  • Such a drum brake has disadvantages. Indeed, once the vehicle is parked and the clamping force is applied, the drum cools and, consequently, retracts. This retraction, while the jaws maintain the same position, leads to an increase in the clamping force which can be so significant that it is no longer possible to release the parking brake.
  • the actuator is of the conventional type, that is to say when it comprises a cable which is pulled mechanically, for example by means of a handbrake lever, in order to move the jaws and implement the clamping force, the retraction of the drum is partly compensated by the elasticity of the cable. However, this compensation is not always sufficient.
  • more and more drum brakes are of the electromechanical type and thus include an electric actuator intended to move the shoes.
  • the connections between the electric actuator and the jaws are more rigid, less elastic, and therefore no longer make it possible to compensate part of the increase in the clamping force caused by the retraction of the drum.
  • the electric actuator may therefore not be able to provide the force necessary to release the drum brake, which causes the vehicle to come to an undesired immobilization.
  • the invention aims in particular to reduce the risk of a drum brake being blocked in the clamping position due to retraction of the drum.
  • the subject of the invention is a drum brake for a motor vehicle, comprising a drum in which two jaws carrying friction means are housed, each jaw forming a lever having a support part, a resistance part and a part forming the power of the lever, the jaws being articulated around a respective pivot and movable between them around their pivot between a rest position, in which they are brought together, and a position of friction with the drum, in which they are apart and the friction means are tightened against the drum, in which at least part of at least one of the jaws is intended to cooperate with at least one complementary member of the drum brake, characterized in that the complementary member is elastically biased in a rest position in the direction of contact with the corresponding part of the jaw.
  • the jaw is not static but, on the contrary, presents a certain degree of mobility thanks to its part which cooperates with a complementary member of the drum brake.
  • this complementary organ is mobile between its rest position and a position which goes against the elastic return and, consequently, the jaw which cooperates with this complementary organ is also mobile.
  • This mobility is particularly advantageous since it allows movement of the jaw to compensate for an increase in clamping force caused by retraction of the drum when it cools.
  • the drum brake thus includes a reserve of elasticity which is particularly advantageous in the case of an electromechanical type drum brake.
  • the complementary member is elastically returned to the rest position which allows the jaw to be positioned according to its normal operating position, the jaw then being ready to apply a clamping force on the drum according to the requests of an actuator.
  • the lever formed by the jaw is, depending on the embodiments, a first class lever, also called inter-support lever, a second class lever, also called inter-resistance lever, or a third class lever, also called inter-motor or inter-power lever.
  • the lever has a power part, a resistance part and a support part, the positioning of these different parts relative to each other being defined by the class to which the lever belongs.
  • the jaws of the drum form a second or third class lever.
  • the invention may also include one or more of the following optional features, taken alone or in combination.
  • the complementary member is formed by the pivot of the jaw and the corresponding part of the jaw is formed by the support of the lever.
  • the complementary member is formed by a member connecting the jaw with an electric actuator of the drum brake and the corresponding part of the jaw is formed by the power of the lever.
  • the complementary member is formed by a sector of the drum and the corresponding part of the jaw is formed by the resistance of the lever.
  • the restoring force is produced by an elastic member pre-stressed in the rest position.
  • the movement of the complementary member and therefore of the jaw which cooperates with this complementary member occurs only when the clamping force resulting from this pressure exceeds the value of the preload.
  • each of the jaws is intended to cooperate with a corresponding complementary member, each complementary member being elastically returned to the rest position in the direction of contact with the corresponding part of the jaw, the complementary member being formed by the respective pivot of each jaw and the corresponding part being formed by the support of the respective lever of each jaw.
  • the ability of the brake to limit the increase in clamping force when the drum retracts while the shoes are in friction position with the drum is thus optimized. It is particularly advantageous that each jaw can be moved to compensate for the retraction of the drum so as to increase the compensation capacity.
  • the jaws cooperating with their respective pivots which are conventionally located nearby in a drum brake, according to one embodiment it can be provided that a single pre-stressed elastic member produces the restoring force in the rest position for the two pivots , which simplifies manufacturing and reduces production costs of the drum brake.
  • each of the jaws is intended to cooperate with a corresponding complementary member, each complementary member being elastically returned to the rest position in the direction of contact with the corresponding part of the jaw, the member complementary being formed by the connecting member with a respective electric actuator of each jaw and the corresponding part being formed by the power of the respective lever of each jaw.
  • each of the jaws is intended to cooperate with a corresponding complementary member, each complementary member being elastically returned to the rest position in the direction of contact with the corresponding part of the jaw, the member complementary being formed by a respective drum sector and the corresponding part being formed by the resistance of the respective lever of each jaw.
  • the pre-stressed elastic member is housed in a housing.
  • This box is advantageously used to prestress the elastic member in a simple and economical manner.
  • the housing is dimensioned so that, when the elastic member is housed in the housing, two opposite walls of the housing form respective support seats for the two ends of the elastic member so as to prestress it to a predetermined prestress value.
  • the use of the box also makes it easier to assemble the drum brake.
  • the value of the preload of the elastic member is between 3,000 and 4,000 N. These are classic clamping force values used for a drum brake, in particular to immobilize the vehicle.
  • the elastic member is thus advantageously stressed only when the clamping force exceeds the clamping force values used during normal operation of the drum brake. We understand that this prevents the elastic member from compensating a clamping force which is useful for braking controlled by a user of the vehicle.
  • the elastic member is therefore advantageously stressed only when the drum retracts and the clamping force is likely to exceed a clamping force for which release of the drum brake is no longer possible.
  • the elastic member is formed by a compression spring. This is a simple and economical way of producing an elastic member according to the invention. According to other embodiments, the elastic member is formed by any other member capable of elastically returning the complementary member to a rest position in the direction of contact with the corresponding part of the jaw.
  • the invention also relates to a vehicle comprising a drum brake as described above.
  • the drum brake is a parking brake. Indeed, it is as a parking brake that the drum brake as described above is most useful. Indeed, it is during parking braking that the drum is most likely to cool and therefore retract by increasing the clamping force on the jaws in the friction position with the drum up to a clamping force value that the actuator is not capable of loosening.
  • FIG. 1 there is a schematic view of a drum brake according to a first embodiment of the invention in which the jaws are shown in the rest position (A) and in the friction position with the drum (B).
  • FIG. 1 there is a schematic sectional view of a drum brake according to the first embodiment of the invention in which the drum is shown expanded (A) or retracted (B);
  • FIG. 1 there is a schematic sectional view of a drum brake according to a second embodiment of the invention in which the drum is shown expanded (A) or retracted (B);
  • FIG. 1 there is a schematic sectional view of a drum brake according to a third embodiment of the invention in which the drum is shown expanded (A) or retracted (B).
  • the invention applies to any type of brake 2, in particular those intended to equip motor vehicles of the tourism type, SUV (English acronym for “Sport Utility Vehicles”), two wheels (in particular motorcycles), airplanes, selected industrial vehicles among vans, "heavy goods vehicles” - that is to say metros, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or engineering machinery civil -, or other transport or handling vehicles.
  • the invention also applies to non-motorized vehicles such as a trailer, a semi-trailer or a caravan.
  • the drum brake 2 is of the electromechanical type and conventionally comprises an electric actuator 4, a drum 5, jaws 6, friction means formed by linings 7 of jaw 6, a plate 8 and at minus a spring 9 for returning the jaws 6 to the rest position (see ).
  • the drum brake 2 also comprises a hydraulic actuator (not shown) for service braking.
  • the drum brake 2 is not of the electromechanical type but, for example, a drum brake 2 with hydraulic and mechanical actuation, comprising a hydraulic actuator intended for service braking and a mechanical actuator intended parking braking formed by a cable actuated, for example, by a handbrake lever.
  • the jaws 6 each carry linings 7 intended to cooperate with the drum 5 to achieve braking.
  • Each jaw 6 is articulated around a respective pivot 10 called fixed point and the jaws 6 are movable between them around their pivot 10 between a rest position (FIG. 2A), in which they are brought together, and a friction position with the drum 5 ( Figure 2B), in which they are spaced apart and the linings 7 are tightened against the drum 5 to achieve braking.
  • the electric actuator 4 is intended to provide the force necessary to move the jaws 6 between their rest position and their friction position with the drum 5. The action of the electric actuator 4 on the jaws 6 is carried out by via a member 17 for connecting the jaw 6 with the electric actuator 4.
  • the jaws 6 each form a lever having a support part 11, a resistance part 12 and a power part 13 of the lever. These parts are understood as the parts classically defined for a lever and which are positioned in relation to each other on the lever depending on the type of lever.
  • each jaw 6 forms a second class lever, also called inter-resistance lever.
  • each jaw 6 forms a first class lever, also called an inter-support lever or a third class lever, also called an inter-motor or inter-power lever.
  • Each jaw 6 has a part intended to cooperate with at least one complementary member of the drum brake 2 5.
  • the complementary member is formed by the respective pivot 10 of each jaw 6
  • the part of each jaw 6 intended to cooperate with the respective pivot 10 is formed by the support 11 of the lever.
  • each pivot 10 is elastically returned to a rest position in the direction C of contact with the support of its respective jaw 6.
  • the restoring force for each pivot 10 is produced by the same elastic member, here a compression spring 14, preloaded in the rest position.
  • the restoring force for each pivot 10 is produced by two springs 14, each pivot 10 cooperating with a respective spring 14.
  • the value of the preload of the spring 14 is between 3,000 and 4,000 N. It is understood that this preload makes it possible to avoid the compression of the spring 14, and therefore the movement of the pivot 10 and the jaw 6, when this is not necessary, that is to say over a range of clamping force values usually used for braking the vehicle 1 and for which the release of the drum brake 2 is not problematic.
  • the value of this preload is different, for example less than 3,000 N or greater than 4,000 N.
  • the preload of the spring 14 is obtained by housing the spring 14 in a housing 15.
  • This housing 15 is thus advantageously dimensioned to preload the spring to preload values of between 3,000 and 4,000 N.
  • the seats support of the two ends of the spring 14 are formed by a shoulder present on each member forming the pivot 10.
  • the shoulder of each pivot 10 is housed in the housing 15 and, in addition to its function of support seat for the spring 14 , makes it possible to limit the movement of the pivot 10 in the direction C of contact with the jaw.
  • each shoulder is pressed by the spring 14 in direction C against a wall of the housing 15 (see Figure 3A).
  • the housing 15 is fixed to the plate 8 by being housed in a cavity 16 formed by the plate 8.
  • two housings 15 are present and each houses one of the springs 14.
  • drum brake 2 5 The implementation of the drum brake 2 5 according to the first embodiment is described below.
  • the brake 2 with drum 5 is regularly requested for service braking, which leads to an increase in the temperature of the drum 5 and, consequently, a relative expansion thereof.
  • the drum 5 then has a first diameter corresponding to a rope D1 in the sectional plane of Figure 3A.
  • a clamping force command is sent to the electric actuator 4 in order to allow the vehicle 1 to be immobilized.
  • the electric actuator 4 moves the jaws 6 from their rest position to their friction position with the drum 5 in order to obtain the controlled clamping force. This movement takes into account the first diameter of the drum 5 in order to obtain the controlled clamping force.
  • the brake 2 with drum 5 gradually cools, causing a retraction of the drum 5 so that it has a second diameter less than the first diameter, this second diameter corresponding to a rope D2 in the plane section of Figure 3B.
  • the jaws 6 being in the friction position with the drum 5 at the time of retraction of the drum 5, this results in an increase in the pressure exerted by the drum 5 on the jaws 6 via their linings 7.
  • This pressure exerted by the drum 5 causes a movement of the jaws 6 in a retraction direction R which is allowed by the movement in the same retraction direction R of their respective pivot 10 which compresses the spring 14 as soon as the clamping force exceeds the preload value of the spring 14 ( Figure 3B).
  • the compression of the spring 14 is done in the present case according to a compression stroke of between 0.5 and 0.6 mm for each end of the spring linked to one of the pivots 10.
  • the movement of the jaws 6 prevents the clamping force from increasing under the effect of the retraction of the drum 5.
  • the risk of blocking the brake 2 with drum 5 in the braking position is thus reduced.
  • the spring 14 plays a role as a reserve of elasticity making it possible to compensate for the retraction of the drum 5.
  • the pivot 10 of only one of the jaws cooperates with the spring 14, the other pivot being fixed. It is then expected that the retraction stroke of the spring 14 is sufficient to compensate for the increases in clamping force caused by the retraction of the drum 5.
  • the retraction stroke of the spring is between 1 and 1.2 mm.
  • This second embodiment differs from the first embodiment mainly by the nature of the complementary member and the part of the jaw 6 intended to cooperate with this complementary member.
  • the complementary member is formed by the member 17 for connecting the jaw 6 with the electric actuator 4 and the corresponding part of the jaw 6 intended to cooperate with this connecting member 17 is formed by the power 13 of the lever.
  • the brake 2 comprises two housings 15 each housing a compression spring 14 preloaded in the rest position as described above.
  • Each box 15 is fixed to the electric actuator 4 on the one hand and cooperates with one of the connecting members 17 on the other hand.
  • drum brake 2 5 The implementation of the drum brake 2 5 according to the second embodiment is described below.
  • the brake 2 with drum 5 is regularly requested for service braking which leads to an increase in the temperature of the drum 5 and therefore an increase in the temperature of the drum 5. relative expansion thereof.
  • the drum 5 then has a first diameter corresponding to a rope D1 in the sectional plane of Figure 4A.
  • a clamping force command is sent to the electric actuator 4 to allow the vehicle to be immobilized.
  • the electric actuator 4 moves the jaws 6 from their rest position to their friction position with the drum 5 in order to obtain the controlled clamping force. This movement takes into account the first diameter of the drum 5 in order to obtain the controlled clamping force (see Figure 4A).
  • the brake 2 with drum 5 gradually cools, causing a retraction of the drum 5 so that it has a second diameter less than the first diameter, this second diameter corresponding to a rope D2 in the plane section of Figure 4B.
  • the jaws 6 being in the friction position with the drum 5 at the time of retraction of the drum 5, this results in an increase in the pressure exerted by the drum 5 on the jaws 6 via their linings 7.
  • This pressure exerted by the drum 5 causes a movement of the jaws 6 in a retraction direction R which is allowed by the movement in the same retraction direction R of the respective connecting members 17 of each jaw 6 which each compress a respective spring 14 as soon as the clamping force exceeds the preload value of the springs 14 ( Figure 4B).
  • the compression of the springs 14 is done in the present case according to a compression stroke of between 0.5 and 0.6 mm for each spring 14.
  • the movement of the jaws 6 prevents the clamping force from increasing under the effect of retraction of the drum 5. The risk of blocking the brake 2 with drum 5 in the braking position is thus reduced.
  • the springs 14 play a role of reserve elasticity making it possible to compensate for the retraction of the drum 5.
  • This third embodiment differs from the first embodiment mainly by the nature of the complementary member and the part of the jaw 6 intended to cooperate with this complementary member.
  • the complementary member is formed by a sector 18 of the drum 5 and the corresponding part of the jaw 6 intended to cooperate with this sector 18 is formed by the resistance 12 of the lever.
  • the third embodiment further differs from the first embodiment in that it comprises two pre-stressed elastic members each formed by a compression spring 14 which is not housed in a housing.
  • the support seats of each spring 14 are formed on the one hand by a sector 18 of respective drum 5 and on the other hand by the side skirt of the drum 5.
  • the springs 14 thus create a space between the sector 18 and the skirt side of the drum 5 with a distance d1 between the drum sector 18 and the side skirt of the drum 5 in thermal expansion condition.
  • the sectors 18 of drum 5 are fixed to the drum 5 so as to be movable relative to it.
  • the preload of the spring 14 is obtained either during its manufacture, or by the compression of the spring 14 resulting from its positioning between the drum sector 18 and the side skirt of the drum 5.
  • drum brake 2 5 The implementation of the drum brake 2 5 according to the third embodiment is described below.
  • the brake 2 with drum 5 is regularly requested for service braking which leads to an increase in the temperature of the drum 5 and therefore an increase in the temperature of the drum 5. relative expansion thereof.
  • the drum 5 then has a first diameter corresponding to a rope D1 in the sectional plane of Figure 5A.
  • a clamping force command is sent to the electric actuator 4 to allow the vehicle to be immobilized.
  • the electric actuator 4 moves the jaws 6 from their rest position to their friction position with the drum 5 in order to obtain the controlled clamping force (Figure 5A). This movement takes into account the first diameter of the drum 5 in order to obtain the controlled clamping force.
  • the brake 2 with drum 5 gradually cools, causing a retraction of the drum 5 so that it has a second diameter less than the first diameter, this second diameter corresponding to a rope D2 in the plane section of Figure 5B.
  • the jaws 6 being in the friction position with the drum 5 at the time of retraction of the drum 5, this results in an increase in the pressure exerted by the drum 5 on the jaws 6 via their linings 7.
  • This pressure exerted by the drum 5 causes a movement of the jaws 6 in a direction of retraction R which is allowed by the movement in the same direction of retraction R of the sectors 18 of the drum each cooperating respectively with one of the jaws and which each compress a respective spring 14 as soon as the force of tightening exceeds the preload value of the springs 14 ( Figure 5B).
  • the distance d2 between the side skirt of the drum 5 and the sector 18 of the drum 5 is less than the distance d1.
  • the compression of the springs 14 is done in the present case according to a compression stroke of between 0.5 and 0.6 mm for each spring 14.
  • the movement of the jaws 6 prevents the clamping force from increasing under the effect of retraction of the drum 5. The risk of blocking the brake 2 with drum 5 in the braking position is thus reduced.
  • the springs 14 play a role of reserve elasticity making it possible to compensate for the retraction of the drum 5.
  • the drum brake 2 5 combines two of the embodiments presented or the three embodiments presented. We thus obtain a brake 2 capable of compensating for greater retraction of the drum 5 and a movement of movement of the jaws 6 which is simplified.
  • the number of pre-stressed elastic members is greater than two, for example between three and ten.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Transportation (AREA)
  • Braking Arrangements (AREA)

Abstract

The drum (5) brake (2) for a motor vehicle (1) comprises a drum housing two jaws (6) carrying friction means (7). Each jaw forms a lever having a support portion (11), a resistance portion (12) and a power portion (13) for supporting, increasing the resistance of and powering the lever. The jaws are articulated around a respective pivot (10) and are mutually movable about their pivots between a rest configuration, wherein they are close together, and a configuration of friction with the drum, wherein they are spaced apart and the friction means are pressed against the drum. At least one portion of at least one of the jaws is intended to co-operate with at least one complementary member of the drum brake. The complementary member is elastically returned to a rest position in the direction (C) of contact with the corresponding portion of the jaw.

Description

Frein à tambour pour véhicule automobileDrum brake for motor vehicle Domaine technique de l’inventionTechnical field of the invention
L’invention se rapporte au domaine des freins à tambour pour véhicule automobile, plus particulièrement aux freins à tambour de type électromécanique utilisés en tant que frein de parking.The invention relates to the field of drum brakes for motor vehicles, more particularly to electromechanical type drum brakes used as a parking brake.
Arrière-plan techniqueTechnical background
Un frein à tambour pour véhicule automobile comporte en général des moyens mécaniques de serrage du frein ou moyens de friction, formés par des garnitures de mâchoires portées par des mâchoires reliées à un actionneur apte à déplacer ces moyens de friction en direction d’un tambour de frein lié en rotation à une roue du véhicule afin de freiner le véhicule par friction, ou les écarter du tambour dans le but de cesser le freinage. Lorsque le frein à tambour est utilisé en tant que frein de parking, l’actionneur déplace les moyens de friction en direction du tambour et les maintient dans cette position tant que le freinage de parking est souhaité. La mise en œuvre du frein de parking a typiquement lieu après avoir utilisé le véhicule pendant un certain temps, afin de le stationner. Ainsi, il est fréquent qu’au moment d’utiliser le frein de parking la température du tambour soit relativement élevée à cause des freinages qui ont eu lieu précédemment au cours de l’utilisation du véhicule. Le tambour est donc dans un état relativement dilaté à cause de cette température élevée et il est ainsi nécessaire d’écarter les mâchoires portant les garnitures en conséquence pour obtenir une force de serrage donnée permettant l’immobilisation du véhicule. A drum brake for a motor vehicle generally comprises mechanical means for applying the brake or friction means, formed by jaw linings carried by jaws connected to an actuator capable of moving these friction means in the direction of a drum of brake linked in rotation to a wheel of the vehicle in order to brake the vehicle by friction, or move them away from the drum in order to stop braking. When the drum brake is used as a parking brake, the actuator moves the friction means towards the drum and holds them in this position as long as parking braking is desired. The application of the parking brake typically takes place after having used the vehicle for a certain period of time, in order to park it. Thus, it is common that when using the parking brake the temperature of the drum is relatively high due to the braking which took place previously during use of the vehicle. The drum is therefore in a relatively expanded state because of this high temperature and it is therefore necessary to separate the jaws carrying the linings accordingly to obtain a given clamping force allowing the vehicle to be immobilized.
Un tel frein à tambour présente des inconvénients. En effet, une fois le véhicule stationné et la force de serrage mise en œuvre, le tambour refroidit et, en conséquence, se rétracte. Cette rétractation, alors que les mâchoires conservent la même position, entraine une augmentation de la force de serrage qui peut être est si importante qu’il n’est alors plus possible de desserrer le frein de parking. Lorsque l’actionneur est de type classique, c’est-à-dire lorsqu’il comprend un câble qui est tiré mécaniquement, par exemple par le biais d’un levier de frein à main, afin de déplacer les mâchoires et mettre en œuvre la force de serrage, la rétractation du tambour est en partie compensée par l’élasticité du câble. Cette compensation n’est toutefois pas toujours suffisante. Par ailleurs, de plus en plus de freins à tambour sont du type électromécanique et comprennent ainsi un actionneur électrique destiné à déplacer les mâchoires. Dans ce cas, les liaisons entre l’actionneur électrique et les mâchoires sont plus rigides, moins élastiques, et ne permettent donc plus de compenser une partie de l’augmentation de la force de serrage causée par la rétractation du tambour. L’actionneur électrique peut ainsi ne pas être capable de fournir l’effort nécessaire pour desserrer le frein à tambour ce qui provoque l’immobilisation non désirée du véhicule.Such a drum brake has disadvantages. Indeed, once the vehicle is parked and the clamping force is applied, the drum cools and, consequently, retracts. This retraction, while the jaws maintain the same position, leads to an increase in the clamping force which can be so significant that it is no longer possible to release the parking brake. When the actuator is of the conventional type, that is to say when it comprises a cable which is pulled mechanically, for example by means of a handbrake lever, in order to move the jaws and implement the clamping force, the retraction of the drum is partly compensated by the elasticity of the cable. However, this compensation is not always sufficient. Furthermore, more and more drum brakes are of the electromechanical type and thus include an electric actuator intended to move the shoes. In this case, the connections between the electric actuator and the jaws are more rigid, less elastic, and therefore no longer make it possible to compensate part of the increase in the clamping force caused by the retraction of the drum. The electric actuator may therefore not be able to provide the force necessary to release the drum brake, which causes the vehicle to come to an undesired immobilization.
L'invention a notamment pour but de réduire le risque qu’un frein à tambour soit bloqué en position de serrage à cause d’une rétractation du tambour.The invention aims in particular to reduce the risk of a drum brake being blocked in the clamping position due to retraction of the drum.
À cet effet, l’invention a pour objet un frein à tambour pour véhicule automobile, comprenant un tambour dans lequel sont logées deux mâchoires portant des moyens de friction, chaque mâchoire formant un levier présentant une partie formant appui, une partie formant résistance et une partie formant puissance du levier, les mâchoires étant articulées autour d’un pivot respectif et déplaçables entre elles autour de leur pivot entre une position de repos, dans laquelle elles sont rapprochées, et une position de friction avec le tambour, dans laquelle elles sont écartées et les moyens de friction sont serrés contre le tambour, dans lequel au moins une partie d’au moins une des mâchoires est destinée à coopérer avec au moins un organe complémentaire du frein à tambour, caractérisé en ce que l’organe complémentaire est rappelé élastiquement dans une position de repos dans le sens du contact avec la partie correspondante de la mâchoire.To this end, the subject of the invention is a drum brake for a motor vehicle, comprising a drum in which two jaws carrying friction means are housed, each jaw forming a lever having a support part, a resistance part and a part forming the power of the lever, the jaws being articulated around a respective pivot and movable between them around their pivot between a rest position, in which they are brought together, and a position of friction with the drum, in which they are apart and the friction means are tightened against the drum, in which at least part of at least one of the jaws is intended to cooperate with at least one complementary member of the drum brake, characterized in that the complementary member is elastically biased in a rest position in the direction of contact with the corresponding part of the jaw.
Ainsi, une fois que la force de serrage est établie, par exemple lors d’un freinage de parking, la mâchoire n’est pas statique mais, au contraire, présente un certain degré de mobilité grâce à sa partie qui coopère avec un organe complémentaire du frein à tambour. En effet, cet organe complémentaire est mobile entre sa position de repos et une position qui va à l’encontre du rappel élastique et, en conséquence, la mâchoire qui coopère avec cet organe complémentaire est elle aussi mobile. Cette mobilité est particulièrement avantageuse puisqu’elle permet un déplacement de la mâchoire permettant de compenser une augmentation de la force de serrage causée par une rétraction du tambour lorsque celui-ci se refroidit. Ainsi, lorsque le tambour se rétracte et presse les moyens de friction portés par la mâchoire, plutôt que d’augmenter l’effort de serrage, il entraine un déplacement de la mâchoire. Le frein à tambour comprend ainsi une réserve d’élasticité qui est particulièrement avantageuse dans le cas d’un frein à tambour de type électromécanique.Thus, once the clamping force is established, for example during parking braking, the jaw is not static but, on the contrary, presents a certain degree of mobility thanks to its part which cooperates with a complementary member of the drum brake. Indeed, this complementary organ is mobile between its rest position and a position which goes against the elastic return and, consequently, the jaw which cooperates with this complementary organ is also mobile. This mobility is particularly advantageous since it allows movement of the jaw to compensate for an increase in clamping force caused by retraction of the drum when it cools. Thus, when the drum retracts and presses the friction means carried by the jaw, rather than increasing the clamping force, it causes a movement of the jaw. The drum brake thus includes a reserve of elasticity which is particularly advantageous in the case of an electromechanical type drum brake.
Une fois que la pression exercée par le tambour sur la mâchoire cesse, par exemple lorsque le frein à tambour est desserré, l’organe complémentaire est rappelé élastiquement en position de repos ce qui permet de positionner la mâchoire selon sa position de fonctionnement normale, la mâchoire étant alors prête à appliquer un effort de serrage sur le tambour en fonction des sollicitations d’un actionneur.Once the pressure exerted by the drum on the jaw ceases, for example when the drum brake is released, the complementary member is elastically returned to the rest position which allows the jaw to be positioned according to its normal operating position, the jaw then being ready to apply a clamping force on the drum according to the requests of an actuator.
On comprend que le levier formé par la mâchoire est, selon les modes de réalisation, un levier de première classe, aussi appelé levier inter-appui, un levier de deuxième classe, aussi appelé levier inter-résistant, ou un levier de troisième classe, aussi appelé levier inter-moteur ou inter-puissant. Dans tous les cas, le levier présente une partie formant puissance, une partie formant résistance et une partie formant appui, le positionnement de ces différentes parties les unes par rapport aux autres étant défini par la classe à laquelle appartient le levier. De manière préférée, les mâchoires du tambour forment un levier de deuxième ou troisième classe.It is understood that the lever formed by the jaw is, depending on the embodiments, a first class lever, also called inter-support lever, a second class lever, also called inter-resistance lever, or a third class lever, also called inter-motor or inter-power lever. In all cases, the lever has a power part, a resistance part and a support part, the positioning of these different parts relative to each other being defined by the class to which the lever belongs. Preferably, the jaws of the drum form a second or third class lever.
L’invention peut également comporter l’une ou plusieurs des caractéristiques optionnelles suivantes, prises seules ou en combinaison.The invention may also include one or more of the following optional features, taken alone or in combination.
L’organe complémentaire est formé par le pivot de la mâchoire et la partie correspondante de la mâchoire est formée par l’appui du levier. On comprend alors que lorsque le tambour se rétracte alors que la mâchoire est en position de friction avec le tambour, la pression exercée par le tambour sur la mâchoire entraine un déplacement de celle-ci qui est permis par le déplacement du pivot de la mâchoire à l’encontre de la force élastique de rappel. Ainsi, ce déplacement de la mâchoire permet de compenser la rétraction du tambour et évite que la force de serrage augmente à un niveau tel que le desserrage du frein à tambour ne soit plus possible.The complementary member is formed by the pivot of the jaw and the corresponding part of the jaw is formed by the support of the lever. We then understand that when the drum retracts while the jaw is in friction position with the drum, the pressure exerted by the drum on the jaw causes a movement of the latter which is allowed by the movement of the pivot of the jaw to against the elastic restoring force. Thus, this movement of the jaw makes it possible to compensate for the retraction of the drum and prevents the clamping force from increasing to a level such that release of the drum brake is no longer possible.
L’organe complémentaire est formé par un organe de liaison de la mâchoire avec un actionneur électrique du frein à tambour et la partie correspondante de la mâchoire est formée par la puissance du levier. On comprend que lorsque le tambour se rétracte alors que la mâchoire est en position de friction avec le tambour, la pression exercée par le tambour sur la mâchoire entraine un déplacement de celle-ci qui est permis par le déplacement de l’organe de liaison avec l’actionneur électrique du frein à tambour à l’encontre de la force élastique de rappel. Ainsi, ce déplacement de la mâchoire permet de compenser la rétractation du tambour et évite que la force de serrage augmente à un niveau tel que le desserrage du frein à tambour ne soit plus possible.The complementary member is formed by a member connecting the jaw with an electric actuator of the drum brake and the corresponding part of the jaw is formed by the power of the lever. We understand that when the drum retracts while the jaw is in friction position with the drum, the pressure exerted by the drum on the jaw causes a movement of the latter which is allowed by the movement of the connecting member with the electric actuator of the drum brake against the elastic return force. Thus, this movement of the jaw makes it possible to compensate for the retraction of the drum and prevents the clamping force from increasing to a level such that release of the drum brake is no longer possible.
L’organe complémentaire est formé par un secteur du tambour et la partie correspondante de la mâchoire est formée par la résistance du levier. On comprend que lorsque le tambour se rétracte alors que la mâchoire est en position de friction avec le tambour, la pression exercée par le tambour sur la mâchoire entraine un déplacement de celle-ci qui est permis par le déplacement du secteur du tambour à l’encontre de la force élastique de rappel. Ainsi, ce déplacement de la mâchoire permet de compenser la rétractation du tambour et évite que la force de serrage augmente à un niveau tel que le desserrage du frein à tambour ne soit plus possible.The complementary member is formed by a sector of the drum and the corresponding part of the jaw is formed by the resistance of the lever. We understand that when the drum retracts while the jaw is in friction position with the drum, the pressure exerted by the drum on the jaw causes a movement of the latter which is allowed by the movement of the sector of the drum to the against the elastic restoring force. Thus, this movement of the jaw makes it possible to compensate for the retraction of the drum and prevents the clamping force from increasing to a level such that release of the drum brake is no longer possible.
La force de rappel est produite par un organe élastique précontraint en position de repos. Ainsi, le déplacement de l’organe complémentaire et donc de la mâchoire qui coopère avec cet organe complémentaire intervient uniquement lorsque la force de serrage résultant de cette pression dépasse la valeur de la précontrainte. Cette caractéristique permet avantageusement d’améliorer le rendement du frein à tambour en évitant qu’une partie trop importante de la force de serrage utile transmise par l’actionneur à la mâchoire ne soit absorbée par l’organe élastique.The restoring force is produced by an elastic member pre-stressed in the rest position. Thus, the movement of the complementary member and therefore of the jaw which cooperates with this complementary member occurs only when the clamping force resulting from this pressure exceeds the value of the preload. This characteristic advantageously makes it possible to improve the efficiency of the drum brake by preventing too large a part of the useful clamping force transmitted by the actuator to the jaw from being absorbed by the elastic member.
Selon un mode de réalisation avantageux, au moins une partie de chacune des mâchoires est destinée à coopérer avec un organe complémentaire correspondant, chaque organe complémentaire étant rappelé élastiquement en position de repos dans le sens du contact avec la partie correspondante de la mâchoire, l’organe complémentaire étant formé par le pivot respectif de chaque mâchoire et la partie correspondante étant formé par l’appui du levier respectif de chaque mâchoire. La capacité du frein à limiter l’augmentation de la force de serrage lorsque le tambour se rétracte alors que les mâchoires sont en position de friction avec le tambour est ainsi optimisée. Il est particulièrement avantageux que chaque mâchoire puisse être déplacée afin de compenser la rétractation du tambour de manière à augmenter la capacité de compensation. En outre, les mâchoires coopérant avec leur pivot respectif qui sont classiquement situés à proximité dans un frein à tambour, on peut prévoir selon un mode de réalisation qu’un unique organe élastique précontraint produise la force de rappel en position de repos pour les deux pivots, ce qui simplifie la fabrication et réduit les coûts de production du frein à tambour.According to an advantageous embodiment, at least a part of each of the jaws is intended to cooperate with a corresponding complementary member, each complementary member being elastically returned to the rest position in the direction of contact with the corresponding part of the jaw, the complementary member being formed by the respective pivot of each jaw and the corresponding part being formed by the support of the respective lever of each jaw. The ability of the brake to limit the increase in clamping force when the drum retracts while the shoes are in friction position with the drum is thus optimized. It is particularly advantageous that each jaw can be moved to compensate for the retraction of the drum so as to increase the compensation capacity. Furthermore, the jaws cooperating with their respective pivots which are conventionally located nearby in a drum brake, according to one embodiment it can be provided that a single pre-stressed elastic member produces the restoring force in the rest position for the two pivots , which simplifies manufacturing and reduces production costs of the drum brake.
Selon un mode de réalisation, au moins une partie de chacune des mâchoires est destinée à coopérer avec un organe complémentaire correspondant, chaque organe complémentaire étant rappelé élastiquement en position de repos dans le sens du contact avec la partie correspondante de la mâchoire, l’organe complémentaire étant formé par l’organe de liaison avec un actionneur électrique respectif de chaque mâchoire et la partie correspondante étant formé par la puissance du levier respective de chaque mâchoire.According to one embodiment, at least a part of each of the jaws is intended to cooperate with a corresponding complementary member, each complementary member being elastically returned to the rest position in the direction of contact with the corresponding part of the jaw, the member complementary being formed by the connecting member with a respective electric actuator of each jaw and the corresponding part being formed by the power of the respective lever of each jaw.
Selon un mode de réalisation, au moins une partie de chacune des mâchoires est destinée à coopérer avec un organe complémentaire correspondant, chaque organe complémentaire étant rappelé élastiquement en position de repos dans le sens du contact avec la partie correspondante de la mâchoire, l’organe complémentaire étant formé par un secteur de tambour respectif et la partie correspondante étant formé par la résistance du levier respective de chaque mâchoire.According to one embodiment, at least a part of each of the jaws is intended to cooperate with a corresponding complementary member, each complementary member being elastically returned to the rest position in the direction of contact with the corresponding part of the jaw, the member complementary being formed by a respective drum sector and the corresponding part being formed by the resistance of the respective lever of each jaw.
L’organe élastique précontraint est logé dans un boitier. Ce boitier est avantageusement utilisé pour précontraindre de manière simple et économique l’organe élastique. Par exemple, le boitier est dimensionné de sorte que, lorsque l’organe élastique est logé dans le boitier, deux parois opposées du boitier forment des sièges d’appui respectifs pour les deux extrémités de l’organe élastique de manière à le précontraindre à une valeur de précontrainte prédéterminée. L’utilisation du boitier permet également de faciliter l’assemblage du frein à tambour.The pre-stressed elastic member is housed in a housing. This box is advantageously used to prestress the elastic member in a simple and economical manner. For example, the housing is dimensioned so that, when the elastic member is housed in the housing, two opposite walls of the housing form respective support seats for the two ends of the elastic member so as to prestress it to a predetermined prestress value. The use of the box also makes it easier to assemble the drum brake.
La valeur de la précontrainte de l’organe élastique est comprise entre 3 000 et 4 000 N. Il s’agit de valeurs classiques de force de serrage utilisées pour un frein à tambour, notamment afin d’immobiliser le véhicule. L’organe élastique est ainsi avantageusement sollicité uniquement lorsque la force de serrage dépasse des valeurs de force de serrage utilisées lors du fonctionnement normal du frein à tambour. On comprend qu’on évite ainsi que l’organe élastique ne compense une force de serrage qui est utile à un freinage commandé par un utilisateur du véhicule. L’organe élastique est donc avantageusement sollicité uniquement lorsque le tambour se rétracte et que la force de serrage est susceptible de dépasser une force de serrage pour laquelle le desserrage du frein à tambour n’est plus possible.The value of the preload of the elastic member is between 3,000 and 4,000 N. These are classic clamping force values used for a drum brake, in particular to immobilize the vehicle. The elastic member is thus advantageously stressed only when the clamping force exceeds the clamping force values used during normal operation of the drum brake. We understand that this prevents the elastic member from compensating a clamping force which is useful for braking controlled by a user of the vehicle. The elastic member is therefore advantageously stressed only when the drum retracts and the clamping force is likely to exceed a clamping force for which release of the drum brake is no longer possible.
L’organe élastique est formé par un ressort de compression. Il s’agit d’un moyen simple et économique de réaliser un organe élastique selon l’invention. Selon d’autres modes de réalisation, l’organe élastique est formé par tout autre organe apte à rappeler élastiquement l’organe complémentaire dans une position de repos dans le sens du contact avec la partie correspondante de la mâchoire.The elastic member is formed by a compression spring. This is a simple and economical way of producing an elastic member according to the invention. According to other embodiments, the elastic member is formed by any other member capable of elastically returning the complementary member to a rest position in the direction of contact with the corresponding part of the jaw.
L’invention a également pour objet un véhicule comprenant un frein à tambour tel que décrit précédemment.The invention also relates to a vehicle comprising a drum brake as described above.
Selon un mode de réalisation préféré, le frein à tambour est un frein de parking. En effet, c’est en tant que frein de parking que le frein de tambour tel que décrit précédemment est le plus utile. En effet, c’est à l’occasion du freinage de parking que le tambour a le plus de chances de se refroidir et donc de se rétracter en augmentant la force de serrage sur des mâchoire en position de friction avec le tambour jusqu’à une valeur de force de serrage que l’actionneur n’est pas capable de desserrer.According to a preferred embodiment, the drum brake is a parking brake. Indeed, it is as a parking brake that the drum brake as described above is most useful. Indeed, it is during parking braking that the drum is most likely to cool and therefore retract by increasing the clamping force on the jaws in the friction position with the drum up to a clamping force value that the actuator is not capable of loosening.
Brève description des figuresBrief description of the figures
L'invention sera mieux comprise à la lecture de la description qui va suivre donnée uniquement à titre d'exemple et faite en se référant aux dessins annexés dans lesquels :The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the appended drawings in which:
la est une vue schématique de dessus d’un véhicule dans lequel un frein à tambour selon l’invention est monté ; there is a schematic top view of a vehicle in which a drum brake according to the invention is mounted;
la est une vue schématique d’un frein à tambour selon un premier mode de réalisation de l’invention dans laquelle les mâchoires sont représentées en position de repos (A) et en position de friction avec le tambour (B). there is a schematic view of a drum brake according to a first embodiment of the invention in which the jaws are shown in the rest position (A) and in the friction position with the drum (B).
la est une vue en coupe schématique d’un frein à tambour selon le premier mode de réalisation de l’invention dans laquelle le tambour est représenté dilaté (A) ou rétracté (B) ; there is a schematic sectional view of a drum brake according to the first embodiment of the invention in which the drum is shown expanded (A) or retracted (B);
la est une vue en coupe schématique d’un frein à tambour selon un deuxième mode de réalisation de l’invention dans laquelle le tambour est représenté dilaté (A) ou rétracté (B) ; there is a schematic sectional view of a drum brake according to a second embodiment of the invention in which the drum is shown expanded (A) or retracted (B);
la est une vue en coupe schématique d’un frein à tambour selon un troisième mode de réalisation de l’invention dans laquelle le tambour est représenté dilaté (A) ou rétracté (B). there is a schematic sectional view of a drum brake according to a third embodiment of the invention in which the drum is shown expanded (A) or retracted (B).
Description détailléedetailed description
On a représenté sur la un véhicule 1 automobile dans lequel le frein 2 à tambour selon l’invention est agencé sur au moins deux roues 3, typiquement les roues arrière.We represented on the a motor vehicle 1 in which the drum brake 2 according to the invention is arranged on at least two wheels 3, typically the rear wheels.
L’invention s’applique à tout type de frein 2, notamment ceux destinés à équiper des véhicules à moteur de type tourisme, SUV (acronyme anglais pour « Sport Utility Vehicles »), deux roues (notamment motos), avions, véhicules industriels choisis parmi les camionnettes, les « Poids - lourds » - c'est-à-dire les métros, bus, engins de transport routier (camions, tracteurs, remorques), les véhicules hors-la-route tels que les engins agricoles ou de génie civil -, ou autres véhicules de transport ou de manutention. L’invention s’applique également aux véhicules non motorisés comme notamment une remorque, une semi-remorque ou une caravane.The invention applies to any type of brake 2, in particular those intended to equip motor vehicles of the tourism type, SUV (English acronym for “Sport Utility Vehicles”), two wheels (in particular motorcycles), airplanes, selected industrial vehicles among vans, "heavy goods vehicles" - that is to say metros, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or engineering machinery civil -, or other transport or handling vehicles. The invention also applies to non-motorized vehicles such as a trailer, a semi-trailer or a caravan.
Premier mode de réalisation (figures 2A à 3B)First embodiment (Figures 2A to 3B)
Dans le cas présent, le frein 2 à tambour est du type électromécanique et comprend de manière classique un actionneur 4 électrique, un tambour 5, des mâchoires 6, des moyens de friction formés par des garnitures 7 de mâchoire 6, un plateau 8 et au moins un ressort 9 de rappel des mâchoires 6 en position de repos (voir ). Selon un mode de réalisation avantageux, le frein 2 à tambour comprend également un actionneur hydraulique (non représenté) pour le freinage de service.In the present case, the drum brake 2 is of the electromechanical type and conventionally comprises an electric actuator 4, a drum 5, jaws 6, friction means formed by linings 7 of jaw 6, a plate 8 and at minus a spring 9 for returning the jaws 6 to the rest position (see ). According to an advantageous embodiment, the drum brake 2 also comprises a hydraulic actuator (not shown) for service braking.
Selon d’autres modes de réalisation, le frein 2 à tambour n’est pas du type électromécanique mais, par exemple, un frein 2 à tambour à actionnement hydraulique et mécanique, comprenant un actionneur hydraulique destiné au freinage de service et un actionneur mécanique destiné au freinage de parking formé par un câble actionné, par exemple, par un levier de frein à main.According to other embodiments, the drum brake 2 is not of the electromechanical type but, for example, a drum brake 2 with hydraulic and mechanical actuation, comprising a hydraulic actuator intended for service braking and a mechanical actuator intended parking braking formed by a cable actuated, for example, by a handbrake lever.
Les mâchoires 6 portent chacune des garnitures 7 destinées à coopérer avec le tambour 5 pour réaliser le freinage. Chaque mâchoires 6 est articulée autour d’un pivot 10 respectif appelé point fixe et les mâchoires 6 sont déplaçables entre elles autour de leur pivot 10 entre une position de repos (figure 2A), dans laquelle elles sont rapprochées, et une position de friction avec le tambour 5 (figure 2B), dans laquelle elles sont écartées et les garnitures 7 sont serrées contre le tambour 5 pour réaliser le freinage. L’actionneur 4 électrique est destiné à fournir la force nécessaire pour déplacer les mâchoires 6 entre leur position de repos et leur position de friction avec le tambour 5. L’action de l’actionneur 4 électrique sur les mâchoires 6 s’effectue par l’intermédiaire d’un organe 17 de liaison de la mâchoire 6 avec l’actionneur 4 électrique.The jaws 6 each carry linings 7 intended to cooperate with the drum 5 to achieve braking. Each jaw 6 is articulated around a respective pivot 10 called fixed point and the jaws 6 are movable between them around their pivot 10 between a rest position (FIG. 2A), in which they are brought together, and a friction position with the drum 5 (Figure 2B), in which they are spaced apart and the linings 7 are tightened against the drum 5 to achieve braking. The electric actuator 4 is intended to provide the force necessary to move the jaws 6 between their rest position and their friction position with the drum 5. The action of the electric actuator 4 on the jaws 6 is carried out by via a member 17 for connecting the jaw 6 with the electric actuator 4.
Les mâchoires 6 forment chacune un levier présentant une partie formant appui 11, une partie formant résistance 12 et une partie formant puissance 13 du levier. Ces parties s’entendent comme les parties classiquement définies pour un levier et qui sont positionnées les unes par rapport aux autres sur le levier en fonction du type de levier. Dans le cas présent, chaque mâchoire 6 forme un levier de deuxième classe, aussi appelé levier inter-résistant. Selon d’autres modes de réalisation chaque mâchoire 6 forme un levier de première classe, aussi appelé levier inter-appui ou un levier de troisième classe, aussi appelé levier inter-moteur ou inter-puissant.The jaws 6 each form a lever having a support part 11, a resistance part 12 and a power part 13 of the lever. These parts are understood as the parts classically defined for a lever and which are positioned in relation to each other on the lever depending on the type of lever. In the present case, each jaw 6 forms a second class lever, also called inter-resistance lever. According to other embodiments, each jaw 6 forms a first class lever, also called an inter-support lever or a third class lever, also called an inter-motor or inter-power lever.
Chaque mâchoire 6 présente une partie destinée à coopérer avec un moins un organe complémentaire du frein 2 à tambour 5. Selon le premier mode de réalisation décrit aux figures 2 et 3, l’organe complémentaire est formé par le pivot 10 respectif de chaque mâchoire 6, et la partie de chaque mâchoire 6 destinée à coopérer avec le pivot 10 respectif est formée par l’appui 11 du levier.Each jaw 6 has a part intended to cooperate with at least one complementary member of the drum brake 2 5. According to the first embodiment described in Figures 2 and 3, the complementary member is formed by the respective pivot 10 of each jaw 6 , and the part of each jaw 6 intended to cooperate with the respective pivot 10 is formed by the support 11 of the lever.
Chaque pivot 10 est rappelé élastiquement dans une position de repos dans le sens C du contact avec l’appui de sa mâchoire 6 respective. Dans le cas présent, la force de rappel pour chaque pivot 10 est produite par un même organe élastique, ici un ressort 14 de compression, précontraint en position de repos. Selon une variante de réalisation, la force de rappel pour chaque pivot 10 est produite par deux ressorts 14, chaque pivot 10 coopérant avec un ressort 14 respectif. Avantageusement, la valeur de la précontrainte du ressort 14 est comprise entre 3 000 et 4 000 N. On comprend que cette précontrainte permet d’éviter la compression du ressort 14, et donc le déplacement du pivot 10 et de la mâchoire 6, lorsque cela n’est pas nécessaire, c’est-à-dire sur une plage de valeurs de force de serrage utilisées habituellement pour le freinage du véhicule 1 et pour lesquelles le desserrage du frein 2 à tambour n’est pas problématique. Selon les modes de réalisation, et notamment en fonction du véhicule 1 sur lequel le frein 2 à tambour 5 est monté, la valeur de cette précontrainte est différente, par exemple inférieure à 3 000 N ou supérieure à 4 000 N.Each pivot 10 is elastically returned to a rest position in the direction C of contact with the support of its respective jaw 6. In the present case, the restoring force for each pivot 10 is produced by the same elastic member, here a compression spring 14, preloaded in the rest position. According to a variant embodiment, the restoring force for each pivot 10 is produced by two springs 14, each pivot 10 cooperating with a respective spring 14. Advantageously, the value of the preload of the spring 14 is between 3,000 and 4,000 N. It is understood that this preload makes it possible to avoid the compression of the spring 14, and therefore the movement of the pivot 10 and the jaw 6, when this is not necessary, that is to say over a range of clamping force values usually used for braking the vehicle 1 and for which the release of the drum brake 2 is not problematic. Depending on the embodiments, and in particular depending on the vehicle 1 on which the drum brake 2 5 is mounted, the value of this preload is different, for example less than 3,000 N or greater than 4,000 N.
Dans le présent mode de réalisation, la précontrainte du ressort 14 est obtenue en logeant le ressort 14 dans un boitier 15. Ce boitier 15 est ainsi avantageusement dimensionné pour précontraindre le ressort à des valeurs de précontrainte comprises entre 3 000 et 4000 N. Les sièges d’appui des deux extrémités du ressort 14 sont formés par un épaulement présent sur chaque organe formant le pivot 10. L’épaulement de chaque pivot 10 est logé dans le boitier 15 et, outre sa fonction de siège d’appui pour le ressort 14, permet de limiter le déplacement du pivot 10 dans le sens C de contact avec la mâchoire. Ainsi, en position de repos, chaque épaulement est pressé par le ressort 14 selon la direction C contre une paroi du boitier 15 (voir figure 3A). Le boitier 15 est fixé au plateau 8 en étant logé dans une cavité 16 formée par le plateau 8. Dans le cas d’une variante de réalisation dans laquelle chaque pivot 10 coopère avec un ressort 14 respectif, deux boitiers 15 sont présents et loge chacun un des ressorts 14.In the present embodiment, the preload of the spring 14 is obtained by housing the spring 14 in a housing 15. This housing 15 is thus advantageously dimensioned to preload the spring to preload values of between 3,000 and 4,000 N. The seats support of the two ends of the spring 14 are formed by a shoulder present on each member forming the pivot 10. The shoulder of each pivot 10 is housed in the housing 15 and, in addition to its function of support seat for the spring 14 , makes it possible to limit the movement of the pivot 10 in the direction C of contact with the jaw. Thus, in the rest position, each shoulder is pressed by the spring 14 in direction C against a wall of the housing 15 (see Figure 3A). The housing 15 is fixed to the plate 8 by being housed in a cavity 16 formed by the plate 8. In the case of a variant embodiment in which each pivot 10 cooperates with a respective spring 14, two housings 15 are present and each houses one of the springs 14.
On décrit ci-après la mise en œuvre du frein 2 à tambour 5 selon le premier mode de réalisation.The implementation of the drum brake 2 5 according to the first embodiment is described below.
Au cours de l’utilisation du véhicule 1, le frein 2 à tambour 5 est régulièrement sollicité pour le freinage de service ce qui entraine une augmentation de la température du tambour 5 et, en conséquence, une dilatation relative de celui-ci. Le tambour 5 présente alors un premier diamètre correspondant à une corde D1 dans le plan de coupe de la figure 3A. À l’issue de l’utilisation du véhicule 1, son stationnement est souhaité. Pour cela, une commande de force de serrage est envoyée à l’actionneur 4 électrique afin de permettre l’immobilisation du véhicule 1. En réponse, l’actionneur 4 électrique déplace les mâchoires 6 de leur position de repos à leur position de friction avec le tambour 5 afin d’obtenir la force de serrage commandée. Ce déplacement prend en compte le premier diamètre du tambour 5 afin d’obtenir la force de serrage commandée. Après l’immobilisation du véhicule 1, le frein 2 à tambour 5 se refroidit progressivement, entrainant une rétractation du tambour 5 de telle sorte qu’il présente un second diamètre inférieur au premier diamètre, ce second diamètre correspondant à une corde D2 dans le plan de coupe de la figure 3B. Les mâchoires 6 étant en position de friction avec le tambour 5 au moment de la rétractation du tambour 5, il en résulte une augmentation de la pression exercée par le tambour 5 sur les mâchoires 6 via leurs garnitures 7. Cette pression exercée par le tambour 5 entraine un déplacement des mâchoires 6 selon une direction de rétractation R qui est permis par le déplacement suivant la même direction de rétractation R de leur pivot 10 respectif qui compriment le ressort 14 dès que la force de serrage dépasse la valeur de précontrainte du ressort 14 (figure 3B). La compression du ressort 14 se fait dans le cas présent selon une course de compression comprise entre 0,5 et 0,6 mm pour chaque extrémité du ressort lié à un des pivots 10. Le déplacement des mâchoires 6 évite que la force de serrage augmente sous l’effet de la rétractation du tambour 5. Le risque de blocage du frein 2 à tambour 5 en position de freinage est ainsi réduit. On comprend que le ressort 14 joue un rôle de réserve d’élasticité permettant de compenser la rétractation du tambour 5.During the use of the vehicle 1, the brake 2 with drum 5 is regularly requested for service braking, which leads to an increase in the temperature of the drum 5 and, consequently, a relative expansion thereof. The drum 5 then has a first diameter corresponding to a rope D1 in the sectional plane of Figure 3A. After using vehicle 1, it is desired to park it. For this, a clamping force command is sent to the electric actuator 4 in order to allow the vehicle 1 to be immobilized. In response, the electric actuator 4 moves the jaws 6 from their rest position to their friction position with the drum 5 in order to obtain the controlled clamping force. This movement takes into account the first diameter of the drum 5 in order to obtain the controlled clamping force. After the immobilization of the vehicle 1, the brake 2 with drum 5 gradually cools, causing a retraction of the drum 5 so that it has a second diameter less than the first diameter, this second diameter corresponding to a rope D2 in the plane section of Figure 3B. The jaws 6 being in the friction position with the drum 5 at the time of retraction of the drum 5, this results in an increase in the pressure exerted by the drum 5 on the jaws 6 via their linings 7. This pressure exerted by the drum 5 causes a movement of the jaws 6 in a retraction direction R which is allowed by the movement in the same retraction direction R of their respective pivot 10 which compresses the spring 14 as soon as the clamping force exceeds the preload value of the spring 14 ( Figure 3B). The compression of the spring 14 is done in the present case according to a compression stroke of between 0.5 and 0.6 mm for each end of the spring linked to one of the pivots 10. The movement of the jaws 6 prevents the clamping force from increasing under the effect of the retraction of the drum 5. The risk of blocking the brake 2 with drum 5 in the braking position is thus reduced. We understand that the spring 14 plays a role as a reserve of elasticity making it possible to compensate for the retraction of the drum 5.
Selon une variante de ce premier mode de réalisation, le pivot 10 d’une seule des mâchoires coopère avec le ressort 14, l’autre pivot étant fixe. On prévoit alors que la course de rétractation du ressort 14 soit suffisante pour compenser les augmentations de force de serrage causées par la rétractation du tambour 5. Par exemple, la course de rétractation du ressort est comprise entre 1 et 1,2 mm.According to a variant of this first embodiment, the pivot 10 of only one of the jaws cooperates with the spring 14, the other pivot being fixed. It is then expected that the retraction stroke of the spring 14 is sufficient to compensate for the increases in clamping force caused by the retraction of the drum 5. For example, the retraction stroke of the spring is between 1 and 1.2 mm.
Deuxième mode de réalisation (figures 4A et 4B)Second embodiment (Figures 4A and 4B)
Ce deuxième mode de réalisation diffère du premier mode de réalisation principalement par la nature de l’organe complémentaire et de la partie de la mâchoire 6 destinée à coopérer avec cet organe complémentaire.This second embodiment differs from the first embodiment mainly by the nature of the complementary member and the part of the jaw 6 intended to cooperate with this complementary member.
Selon le deuxième mode de réalisation, l’organe complémentaire est formé par l’organe 17 de liaison de la mâchoire 6 avec l’actionneur 4 électrique et la partie correspondante de la mâchoire 6 destinée à coopérer avec cet organe 17 de liaison est formée par la puissance 13 du levier.According to the second embodiment, the complementary member is formed by the member 17 for connecting the jaw 6 with the electric actuator 4 and the corresponding part of the jaw 6 intended to cooperate with this connecting member 17 is formed by the power 13 of the lever.
Dans ce mode de réalisation, le frein 2 comprend deux boitiers 15 logeant chacun un ressort 14 de compression précontraint en position de repos tel que décrit précédemment. Chaque boitier 15 est fixé à l’actionneur 4 électrique d’une part et coopère avec un des organes 17 de liaison d’autre part.In this embodiment, the brake 2 comprises two housings 15 each housing a compression spring 14 preloaded in the rest position as described above. Each box 15 is fixed to the electric actuator 4 on the one hand and cooperates with one of the connecting members 17 on the other hand.
On décrit ci-après la mise en œuvre du frein 2 à tambour 5 selon le deuxième mode de réalisation.The implementation of the drum brake 2 5 according to the second embodiment is described below.
De la même manière que pour le premier mode de réalisation, au cours de l’utilisation du véhicule 1, le frein 2 à tambour 5 est régulièrement sollicité pour le freinage de service ce qui entraine une augmentation de la température du tambour 5 et donc une dilatation relative de celui-ci. Le tambour 5 présente alors un premier diamètre correspondant à une corde D1 dans le plan de coupe de la figure 4A. À l’issue de l’utilisation du véhicule 1, son stationnement est souhaité. Pour cela, une commande de force de serrage est envoyée à l’actionneur 4 électrique afin de permettre l’immobilisation du véhicule. En réponse, l’actionneur 4 électrique déplace les mâchoires 6 de leur position de repos à leur position de friction avec le tambour 5 afin d’obtenir la force de serrage commandée. Ce déplacement prend en compte le premier diamètre du tambour 5 afin d’obtenir la force de serrage commandée (voir figure 4A). Après l’immobilisation du véhicule 1, le frein 2 à tambour 5 se refroidit progressivement, entrainant une rétractation du tambour 5 de telle sorte qu’il présente un second diamètre inférieur au premier diamètre, ce second diamètre correspondant à une corde D2 dans le plan de coupe de la figure 4B. Les mâchoires 6 étant en position de friction avec le tambour 5 au moment de la rétractation du tambour 5, il en résulte une augmentation de la pression exercée par le tambour 5 sur les mâchoires 6 via leurs garnitures 7. Cette pression exercée par le tambour 5 entraine un déplacement des mâchoires 6 selon une direction de rétractation R qui est permis par le déplacement suivant la même direction de rétractation R des organes 17 de liaison respectifs de chaque mâchoire 6 qui compriment chacun un ressort 14 respectif dès que la force de serrage dépasse la valeur de précontrainte des ressorts 14 (figure 4B). La compression des ressorts 14 se fait dans le cas présent selon une course de compression comprise entre 0,5 et 0,6 mm pour chaque ressort 14. Le déplacement des mâchoires 6 évite que la force de serrage augmente sous l’effet de la rétractation du tambour 5. Le risque de blocage du frein 2 à tambour 5 en position de freinage est ainsi réduit. On comprend que les ressorts 14 jouent un rôle de réserve d’élasticité permettant de compenser la rétractation du tambour 5.In the same way as for the first embodiment, during the use of the vehicle 1, the brake 2 with drum 5 is regularly requested for service braking which leads to an increase in the temperature of the drum 5 and therefore an increase in the temperature of the drum 5. relative expansion thereof. The drum 5 then has a first diameter corresponding to a rope D1 in the sectional plane of Figure 4A. After using vehicle 1, it is desired to park it. To do this, a clamping force command is sent to the electric actuator 4 to allow the vehicle to be immobilized. In response, the electric actuator 4 moves the jaws 6 from their rest position to their friction position with the drum 5 in order to obtain the controlled clamping force. This movement takes into account the first diameter of the drum 5 in order to obtain the controlled clamping force (see Figure 4A). After the immobilization of the vehicle 1, the brake 2 with drum 5 gradually cools, causing a retraction of the drum 5 so that it has a second diameter less than the first diameter, this second diameter corresponding to a rope D2 in the plane section of Figure 4B. The jaws 6 being in the friction position with the drum 5 at the time of retraction of the drum 5, this results in an increase in the pressure exerted by the drum 5 on the jaws 6 via their linings 7. This pressure exerted by the drum 5 causes a movement of the jaws 6 in a retraction direction R which is allowed by the movement in the same retraction direction R of the respective connecting members 17 of each jaw 6 which each compress a respective spring 14 as soon as the clamping force exceeds the preload value of the springs 14 (Figure 4B). The compression of the springs 14 is done in the present case according to a compression stroke of between 0.5 and 0.6 mm for each spring 14. The movement of the jaws 6 prevents the clamping force from increasing under the effect of retraction of the drum 5. The risk of blocking the brake 2 with drum 5 in the braking position is thus reduced. We understand that the springs 14 play a role of reserve elasticity making it possible to compensate for the retraction of the drum 5.
Troisième mode de réalisation (figures 5A et 5B)Third embodiment (Figures 5A and 5B)
Ce troisième mode de réalisation diffère du premier mode de réalisation principalement par la nature de l’organe complémentaire et de la partie de la mâchoire 6 destinée à coopérer avec cet organe complémentaire.This third embodiment differs from the first embodiment mainly by the nature of the complementary member and the part of the jaw 6 intended to cooperate with this complementary member.
Dans le troisième mode de réalisation, l’organe complémentaire est formé par un secteur 18 du tambour 5 et la partie correspondante de la mâchoire 6 destinée à coopérer avec ce secteur 18 est formée par la résistance 12 du levier.In the third embodiment, the complementary member is formed by a sector 18 of the drum 5 and the corresponding part of the jaw 6 intended to cooperate with this sector 18 is formed by the resistance 12 of the lever.
Le troisième mode de réalisation diffère en outre du premier mode de réalisation en ce qu’il comprend deux organes élastiques précontraints formés chacun par un ressort 14 de compression qui n’est pas logé dans un boitier. Les sièges d’appui de chaque ressort 14 sont formés d’une part par un secteur 18 de tambour 5 respectif et d’autre part par la jupe latérale du tambour 5. Les ressorts 14 créent ainsi un espace entre le secteur 18 et la jupe latérale du tambour 5 avec une distance d1 entre le secteur 18 de tambour et la jupe latérale du tambour 5 en condition de dilatation thermique. Les secteurs 18 de tambour 5 sont fixés au tambour 5 de manière à être mobiles par rapport à celui-ci.The third embodiment further differs from the first embodiment in that it comprises two pre-stressed elastic members each formed by a compression spring 14 which is not housed in a housing. The support seats of each spring 14 are formed on the one hand by a sector 18 of respective drum 5 and on the other hand by the side skirt of the drum 5. The springs 14 thus create a space between the sector 18 and the skirt side of the drum 5 with a distance d1 between the drum sector 18 and the side skirt of the drum 5 in thermal expansion condition. The sectors 18 of drum 5 are fixed to the drum 5 so as to be movable relative to it.
La précontrainte du ressort 14 est obtenue soit lors de sa fabrication, soit par la compression du ressort 14 résultant de son positionnement entre le secteur 18 de tambour et la jupe latérale du tambour 5.The preload of the spring 14 is obtained either during its manufacture, or by the compression of the spring 14 resulting from its positioning between the drum sector 18 and the side skirt of the drum 5.
On décrit ci-après la mise en œuvre du frein 2 à tambour 5 selon le troisième mode de réalisation.The implementation of the drum brake 2 5 according to the third embodiment is described below.
De la même manière que pour le premier mode de réalisation, au cours de l’utilisation du véhicule 1, le frein 2 à tambour 5 est régulièrement sollicité pour le freinage de service ce qui entraine une augmentation de la température du tambour 5 et donc une dilatation relative de celui-ci. Le tambour 5 présente alors un premier diamètre correspondant à une corde D1 dans le plan de coupe de la figure 5A. À l’issue de l’utilisation du véhicule 1, son stationnement est souhaité. Pour cela, une commande de force de serrage est envoyée à l’actionneur 4 électrique afin de permettre l’immobilisation du véhicule. En réponse, l’actionneur 4 électrique déplace les mâchoires 6 de leur position de repos à leur position de friction avec le tambour 5 afin d’obtenir la force de serrage commandée (figure 5A). Ce déplacement prend en compte le premier diamètre du tambour 5 afin d’obtenir la force de serrage commandée. Après l’immobilisation du véhicule 1, le frein 2 à tambour 5 se refroidit progressivement, entrainant une rétractation du tambour 5 de telle sorte qu’il présente un second diamètre inférieur au premier diamètre, ce second diamètre correspondant à une corde D2 dans le plan de coupe de la figure 5B. Les mâchoires 6 étant en position de friction avec le tambour 5 au moment de la rétractation du tambour 5, il en résulte une augmentation de la pression exercée par le tambour 5 sur les mâchoires 6 via leurs garnitures 7. Cette pression exercée par le tambour 5 entraine un déplacement des mâchoires 6 selon une direction de rétractation R qui est permis par le déplacement suivant la même direction de rétractation R des secteurs 18 du tambour coopérant chacun respectivement avec une des mâchoires et qui compriment chacun un ressort 14 respectif dès que la force de serrage dépasse la valeur de précontrainte des ressorts 14 (figure 5B). Une fois les ressorts 14 comprimés, la distance d2 entre la jupe latérale du tambour 5 et le secteur18 de tambour 5 est inférieure à la distance d1. La compression des ressorts 14 se fait dans le cas présent selon une course de compression comprise entre 0,5 et 0,6 mm pour chaque ressort 14. Le déplacement des mâchoires 6 évite que la force de serrage augmente sous l’effet de la rétractation du tambour 5. Le risque de blocage du frein 2 à tambour 5 en position de freinage est ainsi réduit. On comprend que les ressorts 14 jouent un rôle de réserve d’élasticité permettant de compenser la rétractation du tambour 5.In the same way as for the first embodiment, during the use of the vehicle 1, the brake 2 with drum 5 is regularly requested for service braking which leads to an increase in the temperature of the drum 5 and therefore an increase in the temperature of the drum 5. relative expansion thereof. The drum 5 then has a first diameter corresponding to a rope D1 in the sectional plane of Figure 5A. After using vehicle 1, it is desired to park it. To do this, a clamping force command is sent to the electric actuator 4 to allow the vehicle to be immobilized. In response, the electric actuator 4 moves the jaws 6 from their rest position to their friction position with the drum 5 in order to obtain the controlled clamping force (Figure 5A). This movement takes into account the first diameter of the drum 5 in order to obtain the controlled clamping force. After the immobilization of the vehicle 1, the brake 2 with drum 5 gradually cools, causing a retraction of the drum 5 so that it has a second diameter less than the first diameter, this second diameter corresponding to a rope D2 in the plane section of Figure 5B. The jaws 6 being in the friction position with the drum 5 at the time of retraction of the drum 5, this results in an increase in the pressure exerted by the drum 5 on the jaws 6 via their linings 7. This pressure exerted by the drum 5 causes a movement of the jaws 6 in a direction of retraction R which is allowed by the movement in the same direction of retraction R of the sectors 18 of the drum each cooperating respectively with one of the jaws and which each compress a respective spring 14 as soon as the force of tightening exceeds the preload value of the springs 14 (Figure 5B). Once the springs 14 are compressed, the distance d2 between the side skirt of the drum 5 and the sector 18 of the drum 5 is less than the distance d1. The compression of the springs 14 is done in the present case according to a compression stroke of between 0.5 and 0.6 mm for each spring 14. The movement of the jaws 6 prevents the clamping force from increasing under the effect of retraction of the drum 5. The risk of blocking the brake 2 with drum 5 in the braking position is thus reduced. We understand that the springs 14 play a role of reserve elasticity making it possible to compensate for the retraction of the drum 5.
L'invention n'est pas limitée aux modes de réalisation présentés et d'autres modes de réalisation apparaîtront clairement à l'homme du métier. Selon un mode de réalisation, le frein 2 à tambour 5 combine deux des modes de réalisation présentés ou les trois modes de réalisation présentés. On obtient ainsi un frein 2 capable de compenser une plus grande rétractation du tambour 5 et un mouvement de déplacement des mâchoires 6 qui est simplifié. Selon d’autres modes de réalisation, le nombre d’organes élastiques précontraint est supérieur à deux, par exemple compris entre trois et dix.The invention is not limited to the embodiments presented and other embodiments will be clear to those skilled in the art. According to one embodiment, the drum brake 2 5 combines two of the embodiments presented or the three embodiments presented. We thus obtain a brake 2 capable of compensating for greater retraction of the drum 5 and a movement of movement of the jaws 6 which is simplified. According to other embodiments, the number of pre-stressed elastic members is greater than two, for example between three and ten.
Liste de référencesReference list
1 : véhicule automobile
2 : frein à tambour
3 : roue
4 : actionneur électrique
5 : tambour
6 : mâchoire
7 : garnitures de mâchoire
8 : plateau
9 : ressort de rappel des mâchoires en position de repos
10 : pivot
11 : partie formant appui du levier formé par chaque mâchoire
12 : partie formant résistance du levier formé par chaque mâchoire
13 : partie formant puissance du levier formé par chaque mâchoire
14 : ressort de compression
15 : boitier
16 : cavité du plateau 8
17 : organe de liaison de la mâchoire avec l’actionneur électrique
18 : secteur du tambour
C : sens du contact de l’organe complémentaire avec la partie correspondante de la mâchoire
R : direction de rétractation
D1 : corde correspondant au diamètre du tambour dilaté
D2 : corde correspondant au diamètre du tambour rétracté
d1 : distance entre le secteur de tambour et la jupe latérale du tambour dilaté
d2 : distance entre le secteur de tambour et la jupe latérale du tambour rétracté1: motor vehicle
2: drum brake
3: wheel
4: electric actuator
5: drum
6: jaw
7: jaw fittings
8: tray
9: spring returning the jaws to the rest position
10: pivot
11: supporting part of the lever formed by each jaw
12: part forming resistance of the lever formed by each jaw
13: part forming the power of the lever formed by each jaw
14: compression spring
15: case
16: tray cavity 8
17: connecting member of the jaw with the electric actuator
18: drum sector
C: direction of contact of the complementary organ with the corresponding part of the jaw
R: direction of retraction
D1: rope corresponding to the diameter of the expanded drum
D2: rope corresponding to the diameter of the retracted drum
d1: distance between the drum sector and the side skirt of the expanded drum
d2: distance between the drum sector and the side skirt of the retracted drum

Claims (10)

  1. Frein (2) à tambour (5) pour véhicule (1) automobile, comprenant un tambour (5) dans lequel sont logées deux mâchoires (6) portant des moyens (7) de friction, chaque mâchoire (6) formant un levier présentant une partie (11) formant appui, une partie (12) formant résistance et une partie (13) formant puissance du levier, les mâchoires (6) étant articulées autour d’un pivot (10) respectif et déplaçables entre elles autour de leur pivot (10) entre une position de repos, dans laquelle elles sont rapprochées, et une position de friction avec le tambour (5), dans laquelle elles sont écartées et les moyens (7) de friction sont serrés contre le tambour (5), dans lequel au moins une partie (11, 12, 13) d’au moins une des mâchoires (6) est destinée à coopérer avec au moins un organe complémentaire du frein (2) à tambour (5), dans lequel l’organe complémentaire est rappelé élastiquement dans une position de repos dans le sens (C) du contact avec la partie (11, 12, 13) correspondante de la mâchoire (6), caractérisé en ce que le frein (2) à tambour (5) est un frein de parking.Brake (2) with drum (5) for a motor vehicle (1), comprising a drum (5) in which are housed two jaws (6) carrying friction means (7), each jaw (6) forming a lever having a part (11) forming support, a part (12) forming resistance and a part (13) forming power of the lever, the jaws (6) being articulated around a respective pivot (10) and movable between them around their pivot ( 10) between a rest position, in which they are brought together, and a friction position with the drum (5), in which they are spaced apart and the friction means (7) are clamped against the drum (5), in which at least one part (11, 12, 13) of at least one of the jaws (6) is intended to cooperate with at least one complementary member of the drum brake (2) (5), in which the complementary member is recalled elastically in a rest position in the direction (C) of contact with the corresponding part (11, 12, 13) of the jaw (6), characterized in that the brake (2) with drum (5) is a brake car park.
  2. Frein (2) à tambour (5) selon la revendication 1, dans lequel l’organe complémentaire est formé par le pivot (10) de la mâchoire (6) et la partie correspondante de la mâchoire (6) est formée par l’appui (11) du levier.Drum brake (2) (5) according to claim 1, in which the complementary member is formed by the pivot (10) of the jaw (6) and the corresponding part of the jaw (6) is formed by the support (11) of the lever.
  3. Frein (2) à tambour (5) selon la revendication 1 ou 2, dans lequel l’organe complémentaire est formé par un organe (17) de liaison de la mâchoire (6) avec un actionneur (4) électrique du frein (2) à tambour (5) et la partie correspondante de la mâchoire est formée par la puissance (13) du levier.Drum brake (2) (5) according to claim 1 or 2, in which the complementary member is formed by a member (17) for connecting the jaw (6) with an electric actuator (4) of the brake (2) drum (5) and the corresponding part of the jaw is formed by the power (13) of the lever.
  4. Frein (2) à tambour (5) selon l’une quelconque des revendications précédentes, dans lequel l’organe complémentaire est formé par un secteur (18) du tambour (5) et la partie correspondante de la mâchoire (6) est formée par la résistance (12) du levier.Drum brake (2) (5) according to any one of the preceding claims, in which the complementary member is formed by a sector (18) of the drum (5) and the corresponding part of the jaw (6) is formed by the resistance (12) of the lever.
  5. Frein (2) à tambour (5) selon l’une quelconque des revendications précédentes, dans lequel la force de rappel est produite par un organe élastique précontraint en position de repos.Drum brake (2) (5) according to any one of the preceding claims, in which the restoring force is produced by an elastic member pre-stressed in the rest position.
  6. Frein (2) à tambour (5) selon la revendication 2 et 5, dans lequel au moins une partie de chacune des mâchoires (6) est destinée à coopérer avec un organe complémentaire correspondant, chaque organe complémentaire étant rappelé élastiquement en position de repos dans le sens (C) du contact avec la partie correspondante de la mâchoire (6), l’organe complémentaire étant formé par le pivot (10) respectif de chaque mâchoire (6) et la partie correspondante étant formé par l’appui (11) du levier respectif de chaque mâchoire (6).Drum brake (2) (5) according to claims 2 and 5, in which at least a part of each of the jaws (6) is intended to cooperate with a corresponding complementary member, each complementary member being elastically returned to the rest position in the direction (C) of contact with the corresponding part of the jaw (6), the complementary member being formed by the respective pivot (10) of each jaw (6) and the corresponding part being formed by the support (11) of the respective lever of each jaw (6).
  7. Frein (2) à tambour (5) selon la revendication 5 ou 6, dans lequel l’organe élastique précontraint est logé dans un boitier (15).Drum brake (2) (5) according to claim 5 or 6, in which the pre-stressed elastic member is housed in a housing (15).
  8. Frein (2) à tambour (5) selon l’une quelconque des revendications 5 à 7, dans lequel la valeur de la précontrainte de l’organe élastique est comprise entre 3 000 et 4 000 N.Drum brake (2) (5) according to any one of claims 5 to 7, in which the value of the preload of the elastic member is between 3,000 and 4,000 N.
  9. Frein (2) à tambour (5) selon l’une quelconque des revendications 5 à 8, dans lequel l’organe élastique est formé par un ressort (14) de compression.Brake (2) with drum (5) according to any one of claims 5 to 8, in which the elastic member is formed by a compression spring (14).
  10. Véhicule (1) automobile caractérisé en ce qu’il comprend un frein (2) à tambour (5) selon l’une quelconque des revendications précédentes.Motor vehicle (1) characterized in that it comprises a drum brake (2) (5) according to any one of the preceding claims.
PCT/EP2023/062846 2022-05-31 2023-05-12 Drum brake for a motor vehicle WO2023232438A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FRFR2205178 2022-05-31
FR2205178A FR3136026B1 (en) 2022-05-31 2022-05-31 Drum brake for motor vehicle

Publications (1)

Publication Number Publication Date
WO2023232438A1 true WO2023232438A1 (en) 2023-12-07

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2023/062846 WO2023232438A1 (en) 2022-05-31 2023-05-12 Drum brake for a motor vehicle

Country Status (2)

Country Link
FR (1) FR3136026B1 (en)
WO (1) WO2023232438A1 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE424054A (en) * 1937-10-12 1937-12-31
FR2648882A1 (en) * 1989-06-24 1990-12-28 Teves Gmbh Alfred AUTOMATIC RATTRAPAGE ARRANGEMENT FOR A DUO-SERVO DRUM BRAKE

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE424054A (en) * 1937-10-12 1937-12-31
FR2648882A1 (en) * 1989-06-24 1990-12-28 Teves Gmbh Alfred AUTOMATIC RATTRAPAGE ARRANGEMENT FOR A DUO-SERVO DRUM BRAKE

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FR3136026B1 (en) 2024-04-26
FR3136026A1 (en) 2023-12-01

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