GB2352485A - Dissipation of drag rotation in synchronised transmissions - Google Patents
Dissipation of drag rotation in synchronised transmissions Download PDFInfo
- Publication number
- GB2352485A GB2352485A GB9917196A GB9917196A GB2352485A GB 2352485 A GB2352485 A GB 2352485A GB 9917196 A GB9917196 A GB 9917196A GB 9917196 A GB9917196 A GB 9917196A GB 2352485 A GB2352485 A GB 2352485A
- Authority
- GB
- United Kingdom
- Prior art keywords
- transmission
- synchronisation
- arrangement
- gear combination
- selection
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
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
- F16D23/00—Details of mechanically-actuated clutches not specific for one distinct type
- F16D23/02—Arrangements for synchronisation, also for power-operated clutches
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Structure Of Transmissions (AREA)
Abstract
In an automated manual transmission, upon selection of a neutral condition an hydraulic or pneumatic brake load L is applied via actuators 8 and/or 10 to a synchromesh synchronisation mechanism 1,2,3,9 of at least one gear combination in order to brake the transmission (drive shafts 4 and 5) into a substantially stationary condition whereupon potential unbalanced rotation of the transmission is diminished so that there is less likelihood of idle rattle. Several such synchronisation mechanisms may be combined to provide more rapid dissipation. The selected gear combination(s) may be alternated to reduce wear on the respective synchronisation mechanism(s). Alternatively, upon selection of the neutral condition, a forward gear combination synchronisation stage may be performed, whereby drag rotation is dissipated by proportional coupling to the bulk of the transmission ie. increasing the mass of inertia, prior to selection of a reverse gear combination.
Description
2352485 A Transmission Arrangement The present invention relates to a
transmission arrangement and more particularly to a transmission arrangement used within a motor vehicle with regard to selection or placing the arrangement in a neutral configuration where the drive gears of the vehicle are not engaged.
Clearly, within a motor vehicle it is necessary to provide a transmission arrangement through which motive power can be distributed to the wheels of the vehicle. Normally, this transmission arrangement will comprise a gearbox including several respective gear ratio combinations in order to. correlate the necessary torque for vehicle proportion to the engine power output etc. Typically, there will be four or more forward gears and at leas t one reverse gear in order to accommodate a full range of vehicle operational scenarios.
The present invention relates effectively to an automated manual transmission for a motor vehicle. In such an automated manual transmission gear changes are made through appropriate switches activating solenoids in order to displace the necessary gear sets within the transmission to a desired gear ratio combination indicated by such switching initiated by the vehicle driver. It will also be understood that where required the transmission arrangement win also be placed in a neutral condition through simple switch configuration.
In order to effect smooth gear changes between respective gear ratios it is necessary to provide a synchronisation mechanism to bring the respective gears in a gear ratio pairing up to a substantially equivalent rotation speed before meshing the respective gear teeth gears together. Such a mechanism is referred to as a synchromesh. Clearly, synchromesh mechanisms are particularly required when changing between gear ratios whilst the vehicle is in motion.
Unfortunately, when a vehicle is stopped and the transmission therefore placed in neutral, particularly after a period of forward motion, there is a good degree of gearbox momentum or drag rotation which overruns for a period of time. Furthermore, the engine and transmission arrangement will idle with various shafts rotating but without power transfer at lower rotational speed than normal for vehicle motion. This over-run and idle or tick-over conditions can cause disturbing so-called idle rattle noise as a result of a lack of symmetry and harmonics in the transmission arrangement.
Previously, in order to remove or diminish idle rattle it has been known to have a dual mass flywheel which alters its configuration with rotational speed in order to ounter-act these over-run and tick-over idle rattle. However, such dual mass flywheels are more expensive and cannot fully accommodate all transmission arrangement situations.
It is an object of the present invention to provide a transmission arrangement which substantially avoids the above mentioned problems.
In accordance with the present invention there is provided a transmission arrangement for a motor vehicle, the arrangement comprising transmission means including at least one gear combination and a neutral condition where no gear combination is selected with selector means to select therebetween, at least one gear combination including synchronisation means used to synchronise, when selected by the selection means, that gear combination with vehicle drive means through progressive engagement prior to full engagement therebetween, the selection means including control means whereby, when the neutral condition is selected, the synchronisation means of one of the gear combinations is subject to a brake load determined by the control means in order to dissipate any momentum or drag rotation of the transmission means and so diminish any idle rattle of the transmission arrangement in the neutral condition.
Alternatively, in accordance with the present invention there is provided a transmission arrangement for a motor vehicle, the arrangement comprising transmission means including at least one gear combination and a neutral condition where no gear combination is selected with selection means to select therebetween, the 'gear combination including synchronisation means used to synchronise when selected by the selection means, that forward gear combination with vehicle drive means through a synchronisation stage of progressive engagement prior to full engagement therebetween, the arrangement being configured by control means associated with the selection means, whereby when the neutral condition is selected by said selection means then the control means arranges that said synchronisation means performs said synchronization stage of at least one of said forward gear combination in order to dissipate drag rotation of the transmission means through proportional coupling to the bulk of the transmission means prior to engagement of the reverse gear combination with the vehicle drive means.
Typically, the transmission means will be an automated manual transmission. Thus, the selection means will comprise appropriate switches 5 activated by paddles or buttons in order to select a respective gear combination.
Typically, the brake load will be applied through displacement of a suitable brake pad or other actuation mechanism.
The control means may be arranged such that more than one synchronisation means in respective gear combinations may be subjected to a brake load in order to 10 dissipate momentum or drag rotation of the transmission means. Furthermore, the control means may alternate the respective synchronisation means utilised in different gear combinations in order to extend wear and/or provide more rapid dissipation of momentum or rotation of the transmission means. In such circumstances, initially all synchronisation means in all gear combinations may be 5 subjected to a braking load with an incremental reduction in the number of switch synchronisation means subjected to a braking load as momentum or rotation drag of the transmission means is dissipated.
An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings in which:Figtire 1 is a pictorial cross-section of a transmission control arrangement to facilitate selection of a neutral condition; and, Figure 2 is a pictorial side cross-section of the transmission control arrangement depicted in Figure 1 with a forward gear combination engaged.
Operation of synchromesh gears is well known to those skilled in the art.
Thus, specific description directed towards such operation is limited to reference to that known understanding of synchromesh gear operation within motor vehicles.
However, it should be noted that general description with regard to operation of synchromesh gear transmissions in motor vehicles is given in the text books "The Motor Vehicle" published by Butterworth-Heinemann (Newton, Steeds and Garret) twelfth edition, pages 651 to 683 and "Fundamentals of Motor Vehicle Technology" published by Stanley Thorns (Publishers) Limited - Hillier, fourth edition, pages 237 to 243.
In essence, the purpose of a synchromesh or other synchronisation mechanism used with regard to a transmission within a vehicle is to provide two stages of gear combination engagement. In a first stage, which is generally of a progressive nature, the respective rotational speeds of a two sides of the gear combination are brought to substantial equalisation such that in a second stage of full engagement there is a smooth coupling of the gear combination with less jerk and wear through 5 initial gear teeth misalignment etc.
The drawings illustrate a transmission arrangement in accordance with the present invention. The underlying synchromesh -synchronisation mechanism comprises a friction cone 1 and a selector collar 2 incorporating a reciprocal friction surface 3 to engage the friction cone 1. Thus, as the selector 2 is moved in the direction of arrowhead S it will be understood that the friction surface 3 and the friction cone 1 are forced into progressive engagement such that the rotational speed of a primary shaft 4 and a main shaft 5 are substantially equalised. With the primary shaft 4 and main shaft 5 at approximately the same rotational speed, a dog clutch 6 (Figure 2) is then engaged to provide full engagement between the primary shaft 4 and the main shaft 5 for normal power transmission therethrough.
It will be appreciated that the primary shaft 4 and the main shaft 5 are relatively substantial components and thus have momentum when rotated which must be dissipated when disengaged before rotation stops. Thus, when a vehicle stops from a period of forward motion it will be understood that the primary shaft 4 and/or the main shaft 5 may still have a degree of drag rotation as a result of momentum conservation which overruns vehicle motion. In such circumstances, particularly when the vehicle transmission is in neutral the primary shaft 4 or main shaft 5 will still rotate for a period of time.
Clearly, when stopped the vehicle transmission arrangement will be placed in a neutral condition and idle rattle may occur due to momentum over-run i unbalance in the arrangement. By reducing the components such as shafts and gears which are rotating it will be understood that the potential for idle rattle is diminished.
With regard to automated manual transmission arrangements it win be understood that the displacements such as that indicated by arrowhead S will be performed through solenoid actuators (not shown) displacing a selector fork 7 to select the desired gear combination. Similarly, with regard to a neutral condition in an automated manual transmission a simple switch will be operated in order to provide the selection of that neutral condition. In such circumstances, it will be understood that selection of the neutral condition can be relatively rapid and so the transmission arrangement has had inadequate time in order to dissipate the drag rottion overrun of the shafts 4, 5 due to these shafts 4, 5 rotational momentum and there is a potentially greater prospect of idle rattle.
In accordance with the present invention a braking load is applied to the synchronisation mechanism of a gear combination in order to slow the drive shafts 4, 5 of that combination and so dissipate drag rotation due to momentum. Once such drag rotation is dissipated, it will be understood that selection of a neutral condition is then less likely to lead to idle rattle. In such circumstances, as depicted in Figure 1 a brake actuator 8 acts through the selector 2 to engage a synchronising member 9 which engages the main shaft 5. Thus, when a braking load L is applied to the actuator 8 rotation of the shaft 5 is resisted through the braking effect of the load L. In effect, the braking load L ensures dissipation of the momentum in the shaft 5 as a result of forward motion is more quickly dissipated than due to natural transmission configuration friction. Once the shaft 5 has been brought to a substantially stationary condition, it will be appreciated that a thereby substantially "damped" transmission arrangement is then provided which is less likely to lead to unbalanced rotations and idle rattle.
Once the shaft 5 has been slowed or brought to a stationary condition it will be appreciated that the braking load L may be removed prior to or after of the neutral condition or maintained throughout such neutral condition to inhibit idle rattle by reducing the number of rotating shafts etc.
It will be understood that rather than the main shaft 5 being slowed that a similar brake actuator and brake load could be applied to the primary shaft 4 such that this shaft 4 is slowed to a substantially stationary condition upon selection with the neutral condition.
The braking load L may be provided by hydraulic or pneumatic pressure control through a control mechanism associated with selection of the neutral condition.
It will be understood that both the primary shaft 4 and the main shaft 5 may be slowed through an actuator combination of actuator 8 acting upon a peg actuator 10. Thus, the actuator 8 will slow the main shaft 5 through engagement with the peg 10 located in an aperture through the synchronisation member 9 and the peg 10 will be directly forced into braking abutment with the friction cone 1 of the primary shaft 4. In such circumstances, both the shafts 4, 5 will be slowed by the braking load L to a substantially stationary state by the braking load L to stabilise the transmission arrangement and so diminish idle rattle noise. Thus, even though the selection fork 7 has arranged for there to be no transmission of drive between the shafts 4, 5 and so placed the transmission in a neutral configuration there is a braking load L applied between the shafts 4, 5 through the synchronisation progressive engagement surfaces of the friction cone 1 and surface 3 in order to enable the drag rotation of the shafts 4 due to their momentum of rotation to be dissipated quicker than as a result of their natural configuration or friction within a vehicle. By such means, it will be appreciated that selection of a neutral condition within a motor vehicle transmission arrangement is less likely to lead to idle rattle. Furthermore, with an automated manual transmission where there will be a rapid selection of a neutral condition and so higher initial residual drag rotation then the present transmission arrangement will ensure more rapid 5 dispersion of that momentum and so less likelihood of idle rattle..
As indicated above, generally the present transmission control arrangement is used with regard to automated manual transmission systems. In such circumstances, selection of a respective gear combination along with a neutral condition is made through switches which may take the form of paddles or button switches located adjacent the vehicle steering wheel or a Tiptronic gear lever. In any event, a single actuation of the selector switch alters the respective gear combination used by the vehicle and by a single switch actuation or combination provides selection of a neutral condition. The distinct advantage of automated manual gearbox transmissions is that the driver is less distracted by gear changes in that their hands can remain in contact and least adjacent to the vehicle steering wheel.
Typically, as illustrated in Figure 1, the brake actuator 8 or peg actuator 10 may take the form of abutting members into contact with the synchronisation mechanism surfaces of the friction cone 1, surface 3 and the synchronisation member 9. These abutment surfaces will generally may take the form of brake pad type friction materials or more normally conventional synchromesh ring friction material eg. Brass, sintered alloy, carbon or polymers, in order to facilitate dissipation of drag rotation in the transmission i.e. shafts 4, 5.
It will be understood that each respective gear combination of a motor vehicle transmission may include its own actuator 8 and/or actuator peg 10 in order to provide dissipation of drag rotation in the transmission arrangement and so facilitate selection of a neutral condition without idle rattle. In such circumstances, the inherent problem of wear with regard to any load abutment mechanism can be avoided by the controller associated with selection of the neutral condition alternating which particular gear combination synchronisation mechanism is utilised in order to dissipate drag rotation on the transmission. In such circumstances, the period of time over which replacement of worn actuators 8, 10 will be significantly extended.
As each respective synchronisation mechanism may be utilised to facilitate dissipation of drag rotation it will be understood that several such synchronisation mechanisms could be combined in order to provide more rapid dissipation where required. Thus, if a vehicle is rapidly decelerated to a full stop the drag rotation within the transmission arrangement will be relatively high and so if neutral condition is selected a more rapid dissipation of that drag rotation must be achieved by a more aggressive application through a single synchronisation mechanism or by a combination of several such mechanisms. It win also be understood that initially all the synchronisation mechanisms may be utilised in order to dissipate rotation and incrementally, one after another, each such synchronisation mechanism disengaged as the level of drag rotation is diminished.
As an alternative to inclusion of specific actuators 8, 10 it will be understood that drag rotation of the transmission means may be dissipated by increasing the mass of inertia of the transmission. Thus, through a law of conservation of a momentum if, for example, the primary shaft 4 should have a relatively high drag rotation then coupling to a main shaft 5 will transfer some momentum to that shaft 5 such that the coupled combination of shafts 4 and shaft 5 will rotate more slowly. Thus, rather than brake the shafts 4, 5 through specific actuators 8, 10 it will be understood that the normal synchromesh progressive engagement between the friction cone 1 and the surface 9 may be utilised in order to slow the 10transmission and so facilitate selection of a reverse gear combination. Clearly, the more gear combinations through their respective synchronisation mechanisms which are combined into the momentum distributive effect the slower the combined transmission will be. In such circumstances, the controller associated with selection of the neutral condition will determine the necessary number of synchronisation mechanisms in order to dissipate drag rotation of the transmission sufficiently for convenient engagement of that neutral condition by the selection mechanism.
Generally, with regard to the present invention when selecting neutral 10 condition a braking load is applied to one or more of the gear combination synchronisation mechanisms of sufficient force to substantially dissipate and normally stop drag rotation of the transmission due to momentum. However, normally the gear combinations themselves are not selected as these will typically add rather than diminish drag rotation and this rotation will be contrary to that required for the neutral condition with reduced idle rattle. Furthermore, in order to improve wear and tear the or the selection of gear combinations chosen to dissipate drag rotation of the transmission means will be alternated or varied such that each respective synchronisation mechanism of the transmission is not overly burdened and therefore subject to early failure.
In suitable circumstances such as with severe idle rattle where it is necessary to rapidly reduce drag rotation will be appreciated that a gear combination in the opposite direction to that of drag rotation may be momentarily selected to act a heavy brake upon such drag rotation. However, it will be under stood that such operation will place the transmission under extreme strain and so repeated use may lead to premature failure particularly if the same gear combination is used.
Clearly, when a gear combination is selected as depicted in Figure 2 then the brake load L is substantially removed or at least diminished such that normal synchronised transmission drive can be passed through the primary shaft 4 to the main shaft 5 via the synchronisation member 9 or vice versa. Thus, any wear of the actuator 8 or peg 10 is not significant during the long periods of gear combination operation. However, it will also be understood that the top or overdrive forward gear combination may be arranged such that there are no brake load actuators 8, 10 associated with their respective synchronisation mechanisms as long term operation will normally be in these forward gear combinations and so 10 would result in excessive wear to these actuators 8, 10.
I
Claims (12)
1. A transmission arrangement for a motor vehicle, the arrangement comprising transmission means including at least one gear combination and a neutral condition where no gear combination is selected with selector means to select therebetween, at least one gear combination including synchronisation means used to synchronise, when selected by the selection means, the gear combination with vehicle drive means through progressive engagement prior to full engagement therebetween, the selection means including control means whereby, when that neutral condition is selected, the or one of the synchronisation means of the gear combination is subjected to a brake load defined by the control means in order to dissipate drag rotation of the transmission means and so diminish any idle rattle of the transmission means.
2. A transmission arrangement for a motor vehicle, the arrangement comprising transmission means including at least one gear combination and a neutral condition where no gear combination is selected with selection means to select therebetween, the gear combination including synchronisation means used to synchronise when selected by the selection means, that forward gear combination with vehicle drive means through a synchronisation stage of progressive engagement prior to full engagement therebetween, the arrangement being configured by control means associated with the selection means, whereby when the neutral condition is selected by said selection means then the control means arranges that said synchronisation means performs said synchronisation stage of at least one of said forward gear combination in order to dissipate drag rotation of the transmission means through proportional coupling to the bulk of the transmission means prior to engagement of the reverse gear combination with the vehicle drive means.
3. An arrangement as claimed in claim 1 or claim 2 wherein the transmission means is an automated manual gearbox transmission.
4. An arrangement as claimed in claim 1, 2 or 3 wherein the selection means comprises an appropriate switch to activate a solenoid device in order to select one of the forward gear combinations or the neutral condition.
5. An arrangement as claimed in claim I and any claim dependent thereon wherein the brake load is applied by a brake actuator forced into braking abutment with the synchronisation means under a brake load dependent upon the control means.
1
6. An arrangement as claimed in any preceding claim wherein the control means is configured such that more than one synchronisation means in respective gear combinations are utilised to dissipate drag rotation of the transmission means.
7. An arrangement as claimed in claim 6 wherein the control means alternates the specific synchronisation mechanism of each respective forward gear combination used to dissipate drag rotation in order to ameliorate wear between respective synchronisation means of each respective gear combination.
8. An arrangement as claimed in claim 6 or claim 7 wherein the control means is arranged to utilise two or more synchronisation means of respective forward gear combinations in order to more rapidly dissipate drag rotation of the transmission means.
9. An arrangement as claimed in claim 8 wherein the control means is arranged to utilise more than one synchronisation means in order to initially dissipate drag rotation of the transmission means and then incrementally reduce the number of synchronisation means utilised to dissipate drag rotation of the transmission means until the transmission means attains a substantially stationary status.
10. An arrangement as claimed in any preceding claim wherein the control means provides an indication to a driver of a motor vehicle that selection of the reverse gear combination is allowable.
11. A transmission control arrangement substantially as hereinbefore described with reference to the accompanying drawings.
1
12. A motor vehicle including a transmission control arrangement as claimed in any preceding claim.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9917196A GB2352485A (en) | 1999-07-23 | 1999-07-23 | Dissipation of drag rotation in synchronised transmissions |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9917196A GB2352485A (en) | 1999-07-23 | 1999-07-23 | Dissipation of drag rotation in synchronised transmissions |
Publications (2)
Publication Number | Publication Date |
---|---|
GB9917196D0 GB9917196D0 (en) | 1999-09-22 |
GB2352485A true GB2352485A (en) | 2001-01-31 |
Family
ID=10857724
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9917196A Withdrawn GB2352485A (en) | 1999-07-23 | 1999-07-23 | Dissipation of drag rotation in synchronised transmissions |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2352485A (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4584894A (en) * | 1984-02-29 | 1986-04-29 | Borg-Warner Corporation | Transmission anti-clash and anti-rattle brake |
US4785681A (en) * | 1985-04-24 | 1988-11-22 | Honda Giken Kogyo Kabushiki Kaisha | Gear-change apparatus for vehicle transmission |
US5119917A (en) * | 1989-09-30 | 1992-06-09 | Suzuki Jidosha Kogyo Kabushiki Kaisha | Gear knocking sound preventing device for transmission |
EP0866239A2 (en) * | 1997-03-18 | 1998-09-23 | New Venture Gear, Inc. | Multi-speed manual transmission with reverse brake |
-
1999
- 1999-07-23 GB GB9917196A patent/GB2352485A/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4584894A (en) * | 1984-02-29 | 1986-04-29 | Borg-Warner Corporation | Transmission anti-clash and anti-rattle brake |
US4785681A (en) * | 1985-04-24 | 1988-11-22 | Honda Giken Kogyo Kabushiki Kaisha | Gear-change apparatus for vehicle transmission |
US5119917A (en) * | 1989-09-30 | 1992-06-09 | Suzuki Jidosha Kogyo Kabushiki Kaisha | Gear knocking sound preventing device for transmission |
EP0866239A2 (en) * | 1997-03-18 | 1998-09-23 | New Venture Gear, Inc. | Multi-speed manual transmission with reverse brake |
Also Published As
Publication number | Publication date |
---|---|
GB9917196D0 (en) | 1999-09-22 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |