WO2010063376A1 - Automatic transmission - Google Patents

Automatic transmission Download PDF

Info

Publication number
WO2010063376A1
WO2010063376A1 PCT/EP2009/008227 EP2009008227W WO2010063376A1 WO 2010063376 A1 WO2010063376 A1 WO 2010063376A1 EP 2009008227 W EP2009008227 W EP 2009008227W WO 2010063376 A1 WO2010063376 A1 WO 2010063376A1
Authority
WO
WIPO (PCT)
Prior art keywords
piston
retainer element
play
automatic transmission
course
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.)
Ceased
Application number
PCT/EP2009/008227
Other languages
French (fr)
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
Publication of WO2010063376A1 publication Critical patent/WO2010063376A1/en
Anticipated expiration legal-status Critical
Ceased 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 primary or secondary cylinders especially adapted for fluid control

Definitions

  • 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.
  • 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.
  • the piston 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.
  • the gap between the piston and the clutch is fixed as the nominal gap to which the necessary mechanical tolerances are added.
  • 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.
  • 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:
  • 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.
  • 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.
  • FIGURE Ia shows the assembly according to the prior art
  • FIGURE Ib 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
  • FIGURE 2b shows the backward movement of the piston in an assembly according to the present invention.
  • a piston 1 is moveably arranged in a piston chamber 2.
  • a fluid under pressure e.g. oil
  • the spring 3 pushes the piston back until it touches again the back wall of the piston chamber 2.
  • 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.
  • FIGURE Ib the assembly has been modified according to the invention as represented in FIGURE Ib.
  • 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.
  • 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.
  • three grooves 8 are arranged one behind the other in direction of the forward movement of the piston 1.
  • the grooves 8 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 .
  • 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.

Landscapes

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

Abstract

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 order to provide an automatic transmission which shows an essentially constant shift time over its lifetime, it is proposed according to the present invention 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.

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 Ia shows the assembly according to the prior art,
FIGURE Ib 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 Ia, 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 Ib. 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 worthwile 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 8 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

1. 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. 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. 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) .
PCT/EP2009/008227 2008-12-05 2009-11-19 Automatic transmission Ceased WO2010063376A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0822209.3 2008-12-05
GB0822209A GB2466005A (en) 2008-12-05 2008-12-05 A clutch with grooves forming a rail rack wear adjuster

Publications (1)

Publication Number Publication Date
WO2010063376A1 true WO2010063376A1 (en) 2010-06-10

Family

ID=40289533

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2009/008227 Ceased WO2010063376A1 (en) 2008-12-05 2009-11-19 Automatic transmission

Country Status (2)

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

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180313407A1 (en) * 2015-11-04 2018-11-01 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
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
GB2300455A (en) * 1995-05-02 1996-11-06 Automotive Prod France A hydraulic clutch actuator with automatic adjusting device
EP0950827A1 (en) * 1998-04-14 1999-10-20 Mannesmann Sachs Aktiengesellschaft Slave cylinder for a pressure operated clutch

Family Cites Families (3)

* 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
US5749451A (en) * 1996-09-27 1998-05-12 General Motors Corporation Clutch assembly with a piston stroke adjuster

Patent Citations (4)

* 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
GB2300455A (en) * 1995-05-02 1996-11-06 Automotive Prod France A hydraulic clutch actuator with automatic adjusting device
EP0950827A1 (en) * 1998-04-14 1999-10-20 Mannesmann Sachs Aktiengesellschaft Slave cylinder for a pressure operated clutch

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180313407A1 (en) * 2015-11-04 2018-11-01 Schaeffler Technologies AG & Co. KG Torque converter lockup clutch including axial one-way clutch
US10948061B2 (en) * 2015-11-04 2021-03-16 Schaeffler Technologies AG & Co. KG Torque converter lockup clutch including axial one-way clutch

Also Published As

Publication number Publication date
GB0822209D0 (en) 2009-01-14
GB2466005A (en) 2010-06-09

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