GB2466005A - A clutch with grooves forming a rail rack wear adjuster - Google Patents

A clutch with grooves forming a rail rack wear adjuster Download PDF

Info

Publication number
GB2466005A
GB2466005A GB0822209A GB0822209A GB2466005A GB 2466005 A GB2466005 A GB 2466005A GB 0822209 A GB0822209 A GB 0822209A GB 0822209 A GB0822209 A GB 0822209A GB 2466005 A GB2466005 A GB 2466005A
Authority
GB
United Kingdom
Prior art keywords
piston
retainer element
clutch
grooves
groove
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Withdrawn
Application number
GB0822209A
Other versions
GB0822209D0 (en
Inventor
William Jonak
Patrick Barth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GM Global Technology Operations LLC
Original Assignee
GM Global Technology Operations LLC
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 GM Global Technology Operations LLC filed Critical GM Global Technology Operations LLC
Priority to GB0822209A priority Critical patent/GB2466005A/en
Publication of GB0822209D0 publication Critical patent/GB0822209D0/en
Priority to PCT/EP2009/008227 priority patent/WO2010063376A1/en
Publication of GB2466005A publication Critical patent/GB2466005A/en
Withdrawn legal-status Critical Current

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
    • F16D25/00—Fluid-actuated clutches
    • F16D25/06—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch
    • F16D25/062—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces
    • F16D25/063—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially
    • F16D25/0635—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially with flat friction surfaces, e.g. discs
    • F16D25/0638—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially with flat friction surfaces, e.g. discs with more than two discs, e.g. multiple lamellae
    • 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
    • F16D25/00—Fluid-actuated clutches
    • F16D25/12—Details not specific to one of the before-mentioned types
    • F16D25/126—Details not specific to one of the before-mentioned types adjustment for wear or play
    • 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
    • F16D48/00—External control of clutches
    • F16D48/02—Control by fluid pressure
    • F16D2048/0212—Details of pistons for master or slave cylinders especially adapted for fluid control

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)

Abstract

A self adjusting clutch in an automatic transmission comprises a fluid-driven piston 1 for applying clutch plates 4, the piston 1 being moveably arranged in a piston chamber 2, and a spring 3 pushing the piston 1 back in its non-applied position. As the clutch plates 4 wear a gap 5 increases so that shaft time also increases. This problem is overcome by providing a retainer element 6 with one end mounted with play in recess 7 and another end cooperating with grooves 8. The grooves 8 form a rack rail so that as wear occurs the retainer element 6 is pushed from one groove 8 to the next groove 8 so that the gap 5 remains constant.

Description

DESCRIPTION
Automatic transmission The invention concerns an automatic transmission with a fluid-driven piston for applying clutches, the piston being moveably arranged in a piston chamber, a spring pushing the piston back in its non-applied position.
In automatic transmissions according to the prior art, pressurized oil is applied on the front side of the piston, the oil pushing the piston against the effect of the spring towards the clutch plates in order to apply the clutch. In the non-applied position, the piston is pushed by the spring against the wall of the piston chamber, whereas in the applied position it is pushed by the oil against the clutch plates.
The shift time to apply the clutches hereby depends mainly on the gap between the piston and the clutch.
Initially, the gap between the piston and the clutch is fixed as the nominal gap to which the necessary mechanical tolerances are added. However, during use of the transmission, the clutch plates wear off, so that the gap between the piston and the clutch increases by the wear of the plates. Due to the wear of the clutch plates, the shift time increases over the use of the automatic transmission.
It is therefore an objective of the invention to provide an automatic transmission which shows an essentially constant shift time over its lifetime.
This objective is achieved according to the present invention in that a retainer element is fixed with a defined play on the free end of the piston and that at least one groove for receiving the lower end of the retainer element is provided on the inner wall of the area behind the piston.
The piston only can be displaced by the distance defined by the play of the retainer element: When fluid pressure is applied on the front side of the piston, it moves forward until the retainer element fixed on the free end on the rear of the piston stops its course and when the spring pushes the piston backwards in its initial position, the retainer element also stops this course when the end of the play is reached.
Due to the retainer element, it is further possible to avoid that the piston comes to touch the wall of the piston chamber at the end of its backward course thereby increasing the lifetime of the piston.
According to the present invention, a lateral opening is provided on the free end of the piston, the higher end of the retainer element being placed with play into this opening.
The preset play of the retainer element in the opening defines the movement of the piston: it can move forward until the retainer element hits the back end of the opening and backwards until the retainer element hits the front end of the opening.
A preferred embodiment of the invention consists in the fact that two ore more grooves are placed one behind the other one in the direction of course of the piston, the grooves forming a rack rail in order to allow the retainer element to move only from one groove to the next in forward direction of the piston.
This feature allows readjustment of the gap between the piston and the clutch plates during use of the transmission: If the wear of the clutch plates becomes too important, the retainer element is pushed by the fluid pressure acting on the piston from the first groove in which it had been placed initially to the second groove thereby readjusting the gap between the piston and the clutch plate. Due to the inclined bottom of the grooves, the retainer element does not return into its initial position when the piston moves backwards; it retains the piston which now only can move as far as the play of the retainer element allows it.
In the following, the present invention is explained in detail with reference to the drawings in which FIGURE la shows the assembly according to the prior art, FIGURE lb shows the assembly according to the present invention, FIGURE 2a shows the forward movement of the piston in an assembly according to the present invention and FIGURE 2b shows the backward movement of the piston in an assembly according to the present invention.
In FIGURE la, a piston 1 is moveably arranged in a piston chamber 2. A fluid under pressure, e.g. oil, can be applied on the front side of the piston 1 in order to move it forwards towards the clutch plates 4 against the effect of the spring 3. When the fluid pressure decreases, the spring 3 pushes the piston back until it touches again the back wall of the piston chamber 2. However, the gap 5 between the piston 1 and the clutch plates 4 increases over the time with the wear of the clutch plates 4 sot that shift time also increases.
In order to overcome this problem, the assembly has been modified according to the invention as represented in FIGURE lb. It can be seen that the free rear end of the piston 1 has been provided with a retainer element 6. This retainer element 6 is placed with its upper end into an opening 7 of the free rear end of the piston 1 and with its lower end in a groove 8.
It is worthwii.e to note that the retainer element 6 has some play; in the present case it has play in the opening 7, but this play could also be in the groove 8. Due to the retainer element 6, the course of the piston 1 is limited to the play of the retainer element 6. Furthermore, the retainer element 6 avoids that the piston 1 hits on its backward course the back wall of the piston chamber 2.
As shown in FIGURES 2a and 2b, three grooves 8 are arranged one behind the other in direction of the forward movement of the piston 1. The grooves B form a rack rail so that the retainer element 6 can be pushed from the first to the second groove and from the second to the third groove 8 if the gap between the piston 1 and the clutch plates 4 becomes too important.
Due to the rack rail form of the grooves 8, the retainer element 6 cannot return in the groove 8 where it has been before upon the backward movement of the piston 1; it progresses only in forward direction, the progress speed of the retainer element 6 compensating the wear of the clutch plates 4. This self-adjusting play compensation allows to have a uniform gap between the piston 1 and the clutch plates 4 over the lifetime of the automatic transmission.

Claims (3)

  1. CLAIMS1. An automatic transmission with a fluid-driven piston (1) for applying clutches (4), the piston (1) being moveably arranged in. a piston chamber (2), a spring (3) pushing the piston (1) back in its non-applied position, characterized in that a retainer element (6) is fixed with a defined play on the free rear end of the piston (1) and that at least one groove (8) for receiving the lower end of the retainer element (6) is provided on the inner wall of the area behind the piston (1).
  2. 2. The automatic transmission of claim 1, characterized in that a lateral opening (7) is provided on the free end of the piston (1), the higher end of the retainer element (8) being placed with play into this opening (7).
  3. 3. The automatic transmission of claim, characterized in that two ore more grooves (8) are placed one behind the other one in the direction of course of the piston (1), the grooves (8) forming a rack rail in order to allow the retainer element (6) to move only from one groove (8) to the next in forward direction of the piston (1).
GB0822209A 2008-12-05 2008-12-05 A clutch with grooves forming a rail rack wear adjuster Withdrawn GB2466005A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0822209A GB2466005A (en) 2008-12-05 2008-12-05 A clutch with grooves forming a rail rack wear adjuster
PCT/EP2009/008227 WO2010063376A1 (en) 2008-12-05 2009-11-19 Automatic transmission

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0822209A GB2466005A (en) 2008-12-05 2008-12-05 A clutch with grooves forming a rail rack wear adjuster

Publications (2)

Publication Number Publication Date
GB0822209D0 GB0822209D0 (en) 2009-01-14
GB2466005A true GB2466005A (en) 2010-06-09

Family

ID=40289533

Family Applications (1)

Application Number Title Priority Date Filing Date
GB0822209A Withdrawn GB2466005A (en) 2008-12-05 2008-12-05 A clutch with grooves forming a rail rack wear adjuster

Country Status (2)

Country Link
GB (1) GB2466005A (en)
WO (1) WO2010063376A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10948061B2 (en) * 2015-11-04 2021-03-16 Schaeffler Technologies AG & Co. KG Torque converter lockup clutch including axial one-way clutch

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1226375B (en) * 1962-02-07 1966-10-06 Daimler Benz Ag Hydraulic actuating device for disengageable friction clutches, especially for main clutches of motor vehicles
US5307730A (en) * 1992-11-13 1994-05-03 General Motors Corporation Piston return spring system with self-adjusting clearance feature
GB2300455A (en) * 1995-05-02 1996-11-06 Automotive Prod France A hydraulic clutch actuator with automatic adjusting device
US5749451A (en) * 1996-09-27 1998-05-12 General Motors Corporation Clutch assembly with a piston stroke adjuster

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3908804A (en) * 1974-07-11 1975-09-30 Caterpillar Tractor Co Service and parking brake actuation piston with adjuster mechanism
JPH0469414A (en) * 1990-07-09 1992-03-04 Mazda Motor Corp Friction engaging device of automatic transmission
DE19816513A1 (en) * 1998-04-14 1999-10-21 Mannesmann Sachs Ag Actuator for a fluid operated clutch

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1226375B (en) * 1962-02-07 1966-10-06 Daimler Benz Ag Hydraulic actuating device for disengageable friction clutches, especially for main clutches of motor vehicles
US5307730A (en) * 1992-11-13 1994-05-03 General Motors Corporation Piston return spring system with self-adjusting clearance feature
GB2300455A (en) * 1995-05-02 1996-11-06 Automotive Prod France A hydraulic clutch actuator with automatic adjusting device
US5749451A (en) * 1996-09-27 1998-05-12 General Motors Corporation Clutch assembly with a piston stroke adjuster

Also Published As

Publication number Publication date
WO2010063376A1 (en) 2010-06-10
GB0822209D0 (en) 2009-01-14

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)