CN110671453A - Stroke-sensing automatic brake clearance adjusting arm - Google Patents

Abstract

The invention discloses a stroke-sensing automatic brake clearance adjusting arm, which comprises a worm, a clutch spring, a large helical gear, a mandrel, an auxiliary worm, a tripod meshing wheel, a pinion, a control arm, a cover plate, a gear ring, a worm gear and the like which are assembled in a shell, wherein when an automobile brakes or releases braking, the shell rotates around the center of the worm gear, and the control arm drives the large helical gear to rotate through the gear ring, the pinion, the tripod meshing wheel and the auxiliary worm; when the automobile releases the brake, the control arm drives the large helical gear to rotate reversely through the gear ring, the small gear, the three-leg meshing wheel and the auxiliary worm, drives the clutch spring and the worm to drive the worm wheel to rotate, and achieves the purpose of stroke compensation.

Description

Stroke-sensing automatic brake clearance adjusting arm

Technical Field

The invention relates to the technical field of automobile braking systems, in particular to an automatic braking gap adjusting arm with stroke sensing function, which is used for an S-cam drum brake of a commercial vehicle

Background

The automatic brake clearance adjusting arm is called as an automatic adjusting arm for short, and as the name suggests, the automatic brake clearance adjusting arm can be a product capable of automatically adjusting the brake clearance in real time, ensures that the brake clearance is in a proper value, can ensure timely and reliable braking, and is very beneficial to driving safety. In addition, if the automatic adjusting arm is not assembled on the vehicle equipped with the ABS, because the braking clearance is adjusted manually, the consistency of the braking clearance among the wheels is difficult to ensure due to the adjustment of the technical skill, so that the optimal effect cannot be realized under the condition that the force arm and the braking force of different brake cylinders are greatly different.

There are several very distinct benefits of using a brake clearance automatic adjustment arm: the clearance between the friction plate and the brake drum is kept constant, and the braking balance of the vehicle is kept; the optimal braking reaction time is kept, and the performance of the ABS is fully exerted; the thrust and the stroke of the air chamber are utilized to the maximum extent, the loss of compressed air is reduced, and oil is saved; compared with a manual adjusting arm and an automatic gap adjusting arm, the vehicle brake distance can be shortened; the time of maintenance downtime is reduced, and the efficiency is improved.

At present, the automatic brake clearance adjusting arm structures on the market have various structures, and the market share is the largest.

The S-ABA automatic adjusting arm with the Haldex structure comprises a shell, a worm wheel, a worm, a bevel gear clutch, a triangular gear one-way clutch, a small worm wheel and worm pair, a braking rotation angle induction control arm assembly and the like. The size of the brake clearance is sensed by the brake rotation angle when the automobile is braked, and the cone-tooth clutch distinguishes the deformation caused by the rigidity of the brake from the brake rotation angle caused by the brake clearance, so that the automatic adjusting arm can normally identify the excessive brake clearance of the automobile and adjust the excessive brake clearance to the set clearance range, and the brake performance of the automobile is ensured. GB7258-2017 Specification in the Standard of technical Condition for operating safety of Motor vehicles: since 2018 and 1 month later, a vehicle which is newly delivered from factory must be provided with a brake clearance abrasion automatic compensator which is a brake clearance automatic adjusting arm for an S-cam drum brake.

At present, the mainstream products in the market are a European-structure brake clearance automatic adjusting arm represented by Haldex, and in addition, American-structure brake clearance automatic adjustment represented by Bendix and Meritor structures also have certain market share. However, since the latter two are inferior to the former in sealing and adjusting performance, the former is increasingly selected by more host plants.

The automatic brake clearance adjusting arm with the European-style structure represented by Haldex recognizes a normal clearance, an excessive clearance and elastic deformation through sensing the rotating angle of the arm and the reaction force of a received camshaft, and only adjusts the excessive clearance, so that the brake clearance is constant. The structure product has the further characteristics that the sealing performance is good, all moving parts are sealed in the shell, so that the lubricating performance is reliable, the service life is long, and the advantages of the structure product are achieved. However, the structural product has 37 parts due to the complex mechanism, so that the manufacturing cost is high. In the face of intense market competition, some manufacturers in China strive to reduce costs, and since the structure is not changed, cost space is mostly at the expense of quality.

Haldex is a representative european-style structure brake clearance automatic adjusting arm, and when the worm is driven, a set of cone tooth clutches is used for transmitting torque. The maximum transmission torque value M of the group of clutches is determined by the friction coefficient among the conical teeth, the positive pressure F of the worm acting on the clutches and the radius of the conical teeth. Since F is the thrust spring preload F1 — F2 where the worm wheel reacts against the worm, F1 is prone to decline due to spring quality problems, and F2 is large due to wear of vehicle parts and deformation of the load, so that the F becomes small. Once smaller, the value of M will be insufficient to drive the worm to rotate, resulting in failure of the adjustment function.

Haldex is a representative European-structure brake clearance automatic adjusting arm, and is a clearance sensing principle. When the automobile brake system brakes due to high load, the brake drum is easy to generate high temperature. The stiffness of the brake system is reduced and the brake clearance is increased. At this time, the adjusting arm compensates for the increased clearance, and the change in stiffness causes the push rod stroke of the air chamber to be increased to achieve the same braking load. Once the stroke of the push rod of the air chamber exceeds the effective stroke range of the air chamber, the brake task of the automobile can not be effectively finished due to the rapid reduction of the acting force, and the problem of brake fatigue occurs.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and the novel product of the invention provides a stroke-sensing automatic brake clearance adjusting arm with reasonable design and novel structure, which comprises a worm, a clutch spring, a large helical gear, a mandrel, an auxiliary worm, a tripod meshing wheel, a pinion, a control arm, a cover plate, a gear ring, a worm wheel and the like which are assembled in a shell, wherein when an automobile brakes or releases braking, the shell rotates around the center of the worm wheel, and the control arm drives the large helical gear to rotate through the gear ring, the pinion, the tripod meshing wheel and the auxiliary worm; when the automobile releases the brake, the control arm drives the large helical gear to rotate reversely through the gear ring, the small gear, the three-leg meshing wheel and the auxiliary worm, drives the clutch spring and the worm to drive the worm wheel to rotate, and achieves the purpose of stroke compensation.

In order to achieve the purpose, the technical scheme of the invention is as follows: the stroke-sensing automatic brake clearance adjusting arm comprises a worm, a clutch spring, a large helical gear, a screw cap, a mandrel, an auxiliary worm, a three-leg meshing wheel, a pinion, a control arm, a cover plate, a gear ring and a worm gear which are all assembled in a shell, when an automobile brakes or releases braking, the shell rotates around the center of the worm gear, and the control arm drives the large helical gear to rotate through the gear ring, the pinion, the three-leg meshing wheel and the auxiliary worm gear; when the automobile releases the brake, the control arm drives the big helical gear to rotate reversely through the gear ring, the small gear, the three-leg meshing wheel and the auxiliary worm and drives the clutch spring and the worm to drive the worm wheel to rotate so as to achieve the purpose of stroke compensation.

The end face of the rod part of the worm is in contact with the shell, the end face of the tooth part of the worm is not in contact with the end face of the inner hole of the shell, and when the automobile brakes, the reaction force of the worm and the worm wheel is transmitted to the shell through the end face of the rod part of the worm.

The clutch spring 6 is further arranged in a left-handed mode, the worm and the large helical gear are embraced together by means of the inner diameter, and when the worm and the large helical gear rotate anticlockwise relatively, interference of relative movement of the worm and the large helical gear does not occur; when the worm and the large helical gear rotate clockwise relatively, the clutch spring locks the worm and the large helical gear together to rotate relatively, and when the moment of clockwise rotation of the worm and the large helical gear 7 exceeds the elastic damping value of the clutch spring, the worm and the large helical gear can slide.

And further arranging that when the worm and the large helical gear rotate clockwise relatively and the driving torque exceeds a certain value, the holding force of the clutch spring is not enough to continuously maintain the fixed state of the worm and the large helical gear, and the worm and the large helical gear rotate clockwise relatively and slide.

Further provided, the mandrel is free from any axial force; the outer circle of the skirt part of the pinion is contacted with the end of the auxiliary worm, and the tripod meshing wheel does not have any contact position with the pinion along the axial direction.

Further, the three-foot meshing wheel and the pinion are matched together to form a sector space angle a which rotates freely, and the size of the output rotating angle of the adjusting arm is determined by the size of the sector space angle a.

The invention has the beneficial effects that: the invention senses the stroke of the brake air chamber, compensates when the brake stroke exceeds the optimal output force position of the air chamber, ensures stable and reliable braking, and can not make the air chamber forceful because the rigidity of a brake system is reduced due to overheating of a brake drum.

Drawings

FIG. 1 is an exploded view of the structure of the present invention;

FIG. 2 is a schematic cross-sectional view of the present invention;

FIG. 3 is a schematic view of the pinion and three-legged wheel combination of FIG. 1;

FIG. 4 is a partial schematic view of the pinion gear of FIG. 1;

FIG. 5 is a schematic view of the working stroke of the push rod of the air chamber in the application of the present invention;

fig. 6 is a schematic view of the invention shown rotated through an angle when braking a vehicle.

In the figure: the oil nozzle comprises a bushing 1, a shell 2, a grease nozzle 3, a grease nozzle sheath 4, a worm 5, a clutch spring 6, a large bevel gear 7, an O-shaped ring 8, a screw cap 9, a rivet 10, a mandrel 11, a secondary worm 12, a three-leg meshing wheel 13, a pinion 14, a screw 15, a control arm 16, a first O-shaped ring 17, a cover plate 18, a toothed ring 19, a second O-shaped ring 20 and a worm wheel 21.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.

As shown in fig. 1, 2, 3, 4 and 6, the stroke-sensing automatic brake clearance adjusting arm comprises a worm 5, a clutch spring 6, a big bevel gear 7, a screw cap 9, a spindle 11, a secondary worm 12, a triangle gear 13, a pinion 14, a control arm 16, a cover plate 18, a toothed ring 19 and a worm wheel 21 which are all assembled in a housing 2, when the automobile brakes or releases the brake, the housing 2 rotates around the center of the worm wheel 21, and the control arm 16 drives the big bevel gear 7 to rotate through the toothed ring 19, the pinion 14, the triangle gear 13 and the secondary worm 12; when the automobile releases the brake, the control arm 16 drives the large helical gear 7 to rotate reversely through the gear ring 19, the pinion 14, the tripod wheel 13 and the auxiliary worm 12, and drives the clutch spring 6 and the worm 5 to drive the worm wheel 21 to rotate, so as to achieve the purpose of stroke compensation. The end face of the rod part of the worm 5 is contacted with the shell 2, but the end face of the tooth part of the worm 5 is not contacted with the end face of the inner hole of the shell 2, when the automobile brakes, the reaction force of the worm 5 on the worm wheel 21 is completely transmitted to the shell 2 by the end face of the rod part of the worm 5.

The clutch spring 6 rotates left and embraces the worm 5 and the big helical gear 7 together by the inner diameter, and when the worm 5 and the big helical gear 7 rotate anticlockwise relatively, the relative motion of the two does not interfere; when the worm 5 and the large helical gear 7 rotate clockwise relatively, the clutch spring 6 locks the worm 5 and the large helical gear 7 together to rotate relatively, and when the moment of the relative clockwise rotation of the worm 5 and the large helical gear 7 exceeds the elastic damping value of the clutch spring 6, the worm 5 and the large helical gear 7 can slide.

When the worm 5 and the large helical gear 7 rotate clockwise relatively and the driving torque exceeds a certain value, the holding force of the clutch spring 6 is not enough to keep the fixed state of the worm 5 and the large helical gear 7 continuously, and the worm 5 and the large helical gear 7 rotate clockwise relatively and slide.

The mandrel 11 is not subjected to any axial force; the outer circle of the skirt of the pinion 14 is contacted with the end of the auxiliary worm 12, and the three-leg meshing wheel 13 is not in any contact position with the pinion 14 along the axial direction.

The three-leg meshing wheel 13 and the pinion 14 are matched together to form a sector space angle a which rotates freely, and the size of the output rotation angle of the adjusting arm is determined by the size of the sector space angle a.

The bush 1 is inlayed to the upper end stalk portion of casing 2, does benefit to external brake line, and casing 2 upper right position is equipped with the worm 5 intercommunication of grease nipple 3 and interior establishing, and 3 overcoat of grease nipple connects glib sheath 4.

Establish O type circle 8 between the connection terminal surface of big helical gear 7 and spiral shell lid 9, establish O type circle 17 between the connection terminal surface of apron 18 and control arm 16, establish O type circle two 20 between the blind hole bottom connection terminal surface of worm wheel 21 and casing 2, the setting of above-mentioned O type circle can be avoided inside butter to be heated the attenuation and spills over.

The automatic brake clearance adjusting mechanism part of the technical scheme determines the stroke of the air chamber by sensing the self-rotating angle as shown in figure 5, always controls the stroke of the air chamber within 2/3 of S of the total stroke, and ensures that the brake air chamber works at the optimal position. When the brake lining is worn, the air chamber stroke is increased when the brake is finished, at the moment, the rotating angle of the adjusting arm is increased, and when the brake is released and returns to the final stage, the adjusting arm can automatically compensate the brake clearance, so that the air chamber stroke returns to the optimal range, namely the total stroke of the air chamber is within 2/3.

As shown in fig. 1, the control arm 16 of the adjusting arm is connected to the toothed ring 19 so that it cannot move relative to it. When the automobile is braked, the shell 2 rotates forwards, and the control arm 16 and the riveted toothed ring 19 can only rotate reversely relative to the shell 2 because the control arm 16 is fixed on the axle and cannot move, and the toothed ring 19 drives the pinion 14 to rotate.

As shown in the left drawing of fig. 3, the pinion 14 and the tripod meshing wheel 13 are sleeved together, and three sector space angles are formed between the pinion 14 and the tripod meshing wheel along the circumferential direction, wherein the angle is a; as shown in the right drawing of fig. 3, when the pinion 14 rotates a, the sector angle between the two shifts to the other side; this is a key parameter in determining the amount of the adjustment arm's angle of rotation.

As shown in fig. 2, the worm 5 is connected to a large helical gear 7 through a clutch spring 6. The clutch spring 6 is left-handed, and when in a free state, the inner diameter is slightly smaller than the outer diameter of the matched part of the worm 5 and the large helical gear 7. When the worm 5 and the large helical gear 7 rotate in the counterclockwise direction relatively, the clutch spring 6 is in an outward expansion potential state, so that the worm 5 and the large helical gear 7 cannot be fixed, and the worm 5 and the large helical gear can rotate independently and relatively. When the worm 5 and the large helical gear 7 rotate clockwise relatively, the clutch spring 6 is in an inward holding state, so that the worm and the large helical gear are firmly bound, and the worm and the large helical gear cannot rotate independently and only can rotate together.

As shown in fig. 2, a flat surface 52a is formed on the end surface of the shaft portion of the worm 5 and contacts the inner end surface 2a of the housing 2. The end face of the teeth of the worm 5 is kept at a certain clearance 52a from the end face of the inner side of the housing 2, and the two can not contact. The other end of the worm 5 is contacted with the end face of a big helical gear 7, the big helical gear 7 is limited by a screw cap 9, and the screw cap 9 is screwed in the shell 2 by the thread of the screw cap 9. The worm 5, the large helical gear 7, and the clutch spring 6 are thus confined within the housing 2.

After the screw cap 9 is screwed, the large helical gear 7 is not forced to be pressed, but a certain gap is formed, so that the worm 5 and the large helical gear 7 can rotate freely.

The three-foot meshing wheel 13 and the auxiliary worm 12 are firmly sleeved into a whole through a spline. Three fan-shaped legs of the tripod wheel 13 extend into three fan-shaped notches in the middle of the pinion 14, and a space is formed between the three fan-shaped notches, as shown in fig. 3, and the three fan-shaped notches and the pinion can rotate relative to each other within the angle range. The tripod wheel 13 and the pinion 14 are held with a certain gap in the axial direction and are not in contact with each other.

The three-leg meshing wheel 13, the auxiliary worm 12 and the pinion 14 are fixedly connected in series through the mandrel 11 and can rotate together. The end face of one side of the auxiliary worm 12 contacts with the outer circle end of the skirt of the pinion 14, and the two are respectively limited by the shell 2 and the cover plate 18 and cannot move along the axial direction.

When the adjusting arm body is in an independent state (before being arranged on an axle), no external force is applied to the worm 5 because the worm wheel 21 is free from any external force. At this time, the fixed housing 2 can easily rotate the control arm 16 in both forward and reverse directions, and the control arm 16 drives the worm wheel 21 to rotate in both forward and reverse directions through the gear ring 19, the pinion 14, the auxiliary worm 12, the large helical gear 7, the clutch spring 6 and the worm 5.

When the adjuster arm body is assembled to the axle, a reaction torque (referred to as residual torque) is always present on the worm wheel 21 due to the reaction force of the cam shaft from the brake shoe return spring, regardless of whether the vehicle is braking. Due to this moment, the worm wheel 21 exerts a force (F2 mentioned above) on the worm 5, so that the end face of the worm 5 presses against the inner bore end of the housing 2. In this way, no matter how the worm 5 is rotated, there is a resistance torque M3 in the opposite direction.

When the vehicle is to be braked, the air chamber pushes the adjustment arm housing 2 forward (in fig. 6, in a counterclockwise direction), and since the control arm 16 is fixed, it rotates clockwise relative to the housing 2, driving the pinion 14 to rotate via the toothed ring 19. When the adjusting arm rotates by the angle C DEG required for normal braking, the contact position of the pinion 14 and the three-foot meshing wheel 13 is changed from the left position state in figure 3 to the right position state in figure 3.

Because the brake clearance is too large, the automobile brake is not completed at this time, and the air chamber continues to push the shell 2 to rotate forwards by an angle of E degrees. At this time, the control arm 16 rotates the tripod wheel via the ring gear 19 and the pinion 14, and further rotates the pinion worm 12 and the large helical gear 7. At this time, the large helical gear 7 and the worm 5 rotate in a counter-clockwise direction, and because the acting force of the clutch spring 6 is small, the generated torque is smaller than M3 (the torque of the worm 5 is resisted by the friction of the shell 2), the worm 5 cannot be driven to rotate, and then the large helical gear rotates at an angle position relative to the worm until the automobile is braked.

The car is then braked: when the air chamber is deflated and retracted in the reverse direction to drive the adjusting arm housing 2 to rotate at an angle C ° clockwise as shown in fig. 6, the control arm 16 drives the pinion 14 to rotate in the reverse direction through the toothed ring 19, and the contact position of the pinion 14 and the tripod meshing wheel 13 is shifted from the position shown in the right side of the figure to the position shown in the left side of the figure.

Since the adjusting arm is not yet returned to the original position, the air chamber continues to drive the housing 2 back clockwise until the angle of E is passed, at which time the adjusting arm returns to the original position. In the process, the control arm 16 drives the large bevel gear 7 to rotate through the gear ring 19, the pinion 14, the tripod wheel 13 and the auxiliary worm 12. The large bevel gear 7 and the worm 5 attempt to rotate in a clockwise direction relative to each other. Since the clutch spring 6 tightly locks the large bevel gear 7 and the worm 5 together, the large bevel gear 7 drives the worm 5 to rotate along the needle, thereby driving the worm wheel 21 to rotate forwards at an angle. The results were: when the adjusting arm returns to the original position, the worm wheel 21 does not return to the original position, the camshaft sleeved with the worm wheel cannot be added to the original position, but rotates an angle towards the brake loading direction, and then the clearance between the brake lining and the brake drum is reduced, so that the purpose of automatic compensation is achieved.

The above process is repeated for many times, and finally the brake clearance is adjusted to be within the range required by people.

The invention has the advantages that:

1 relative to the European-style structure automatic adjusting arm represented by Haldex, the structure is simple, and the number of parts is only 21.

2 has no thrust spring, and can not influence the change of the adjusting moment due to the decline of the spring performance and the change of the reaction force of the camshaft, thereby influencing the output performance.

3 the external dimension is smaller than the European-structure automatic adjusting arm represented by Haldex, and the device is particularly suitable for 'light commercial vehicles with limited space'.

4 this product is to the stroke of brake chamber perception, compensates when the braking stroke surpasss the best output power position of air chamber, and the braking of having guaranteed is reliable and stable, can not make the air chamber forcefully unable to go out because of overheated brake drum leads to the braking system rigidity to reduce.

The invention inherits the characteristics of excellent sealing performance and convenient installation and use of the European-type structure adjusting arm, reduces the number of parts of a product assembly from 37 to 21 by optimizing the structure, and can greatly reduce the use and manufacture cost.

When the brake of the vehicle is completely released, the adjusting arm returns to the initial position, and the worm 20 and the camshaft do not return to the initial position but rotate forwards by an angle, so that the clearance between the brake lining and the brake drum is reduced, and the purpose of clearance compensation is achieved.

In the present invention, there is no bevel clutch, no thrust spring. Therefore, the product cannot cause the failure of the adjusting function due to the change of the two.

The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the claims of the present invention.

Claims (6)

1. The brake clearance automatic adjustment arm of stroke perception, its characterized in that: the automobile brake device comprises a worm (5), a clutch spring (6), a large helical gear (7), a screw cap (9), a mandrel (11), an auxiliary worm (12), a three-leg meshing wheel (13), a pinion (14), a control arm (16), a cover plate (18), a gear ring (19) and a worm gear (21) which are all assembled in a shell (2), wherein when an automobile brakes or releases the braking, the shell (2) rotates around the center of the worm gear (21), and the control arm (16) drives the large helical gear (7) to rotate through the gear ring (19), the pinion (14), the three-leg meshing wheel (13) and the auxiliary worm (12); when the automobile releases the brake, the control arm (16) drives the large helical gear (7) to rotate reversely through the gear ring (19), the pinion (14), the three-foot meshing wheel (13) and the auxiliary worm (12) and drives the clutch spring (6) and the worm (5) to drive the worm wheel (21) to rotate so as to achieve the purpose of stroke compensation.

2. The stroke-aware brake clearance automatic adjustment arm of claim 1, wherein: the end face of the rod part of the worm (5) is in contact with the shell (2), the end face of the tooth part of the worm (5) is not in contact with the end face of the inner hole of the shell (2), and when the automobile brakes, the reaction force of the worm (5) on the worm wheel (21) is transmitted to the shell (2) from the end face of the rod part of the worm (5).

3. The stroke-aware brake clearance automatic adjustment arm of claim 1, further comprising: the clutch spring (6) rotates left and embraces the worm (5) and the large helical gear (7) together by means of the inner diameter, and when the worm (5) and the large helical gear (7) rotate counterclockwise relatively, the relative motion of the worm (5) and the large helical gear (7) is not interfered; when the worm (5) and the large helical gear (7) rotate clockwise relatively, the clutch spring (6) locks the worm (5) and the large helical gear (7) together to rotate relatively, and when the moment of the relative clockwise rotation of the worm (5) and the large helical gear (7) exceeds the elastic damping value of the clutch spring (6), the worm (5) and the large helical gear (7) can slide.

4. The stroke-aware brake clearance automatic adjustment arm of claim 3, further comprising: when the worm (5) and the large helical gear (7) rotate clockwise relatively and the driving torque exceeds a certain value, the holding force of the clutch spring (6) is not enough to keep the fixed state of the worm (5) and the large helical gear (7) continuously, and the worm (5) and the large helical gear (7) rotate clockwise relatively and slide.

5. The stroke-aware brake clearance automatic adjustment arm of claim 1, wherein: the mandrel (11) is free from any axial force; the outer circle of the skirt part of the pinion (14) is contacted with the end of the auxiliary worm (12), and the tripod meshing wheel (13) does not have any contact position with the pinion (14) along the axial direction.

6. The stroke-aware brake clearance automatic adjustment arm of claim 5, wherein: the three-foot meshing wheel (13) and the pinion (14) are matched together to form a sector space angle a which rotates freely, and the size of the output rotating angle of the adjusting arm is determined by the size of the sector space angle a.

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