WO2008099005A1 - Device for actuating a clutch in an automatic transmission - Google Patents

Device for actuating a clutch in an automatic transmission Download PDF

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Publication number
WO2008099005A1
WO2008099005A1 PCT/EP2008/051859 EP2008051859W WO2008099005A1 WO 2008099005 A1 WO2008099005 A1 WO 2008099005A1 EP 2008051859 W EP2008051859 W EP 2008051859W WO 2008099005 A1 WO2008099005 A1 WO 2008099005A1
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WO
WIPO (PCT)
Prior art keywords
valve
clutch
accumulator
pressure
magnetic force
Prior art date
Application number
PCT/EP2008/051859
Other languages
French (fr)
Inventor
Marc Rambert
Original Assignee
Gm Global Technology Operations, Inc.
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, Inc. filed Critical Gm Global Technology Operations, Inc.
Publication of WO2008099005A1 publication Critical patent/WO2008099005A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0401—Valve members; Fluid interconnections therefor
    • F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/044—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by electrically-controlled means, e.g. solenoids, torque-motors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/044—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by electrically-controlled means, e.g. solenoids, torque-motors
    • F15B13/0442—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by electrically-controlled means, e.g. solenoids, torque-motors with proportional solenoid allowing stable intermediate positions
    • 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
    • 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
    • F16D48/06—Control by electric or electronic means, e.g. of fluid pressure
    • F16D48/066—Control of fluid pressure, e.g. using an accumulator
    • 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
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/02—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used
    • F16H61/0202—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric
    • F16H61/0251—Elements specially adapted for electric control units, e.g. valves for converting electrical signals to fluid signals
    • 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
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/04—Smoothing ratio shift
    • F16H61/06—Smoothing ratio shift by controlling rate of change of fluid pressure
    • F16H61/065—Smoothing ratio shift by controlling rate of change of fluid pressure using fluid control means
    • F16H61/067—Smoothing ratio shift by controlling rate of change of fluid pressure using fluid control means using an accumulator
    • 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
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K31/00—Actuating devices; Operating means; Releasing devices
    • F16K31/02—Actuating devices; Operating means; Releasing devices electric; magnetic
    • F16K31/06—Actuating devices; Operating means; Releasing devices electric; magnetic using a magnet, e.g. diaphragm valves, cutting off by means of a liquid
    • F16K31/0603—Multiple-way valves
    • F16K31/061—Sliding valves
    • F16K31/0613—Sliding valves with cylindrical slides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50554—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing valve
    • 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
    • F16D2048/0203—Control by fluid pressure with an accumulator; Details thereof
    • 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
    • F16D2048/0209—Control by fluid pressure characterised by fluid valves having control pistons, e.g. spools
    • 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
    • F16D2048/0221—Valves for clutch control systems; Details thereof
    • 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
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/10—System to be controlled
    • F16D2500/102—Actuator
    • F16D2500/1026—Hydraulic
    • F16D2500/1027—Details about the hydraulic valves

Definitions

  • the invention relates to a device for actuating a clutch in an automatic transmission.
  • VBS variable bleed solenoid
  • aspects of the present invention seek to diminish the number of valves in the hydraulic circuit and to render the control of the valve less dependent on the working conditions.
  • This object is achieved according to the invention by a device for actuating a clutch in an automatic transmission, wherein a controlling and regulating valve is directly connected with its rear chamber to the clutch with means for applying a magnetic force on the front side of the valve and the line pressure force on the rear side and wherein the valve is configured in that upon applying a magnetic force on the front side of the valve, the line pressure is applied to the clutch and wherein an accumulator acting as low frequency filter is integrated into the rear chamber.
  • the rear side of the valve In order to maintain pressure inside the clutch, the rear side of the valve is directly connected to the clutch thereby exposing the valve to the pressure inside the clutch.
  • Fmag the magnetic force
  • Fp the pressure force
  • these two forces are identical because the valve tends to an equilibrium position (this supposes that no leakage appears in the hydraulic circuit between valve and clutch, otherwise with a small leakage a correction on the magnetic force would be necessary to guarantee the clutch pressure) .
  • the valve functions as follows: In the beginning, there is no pressure in the clutch. A magnetic force (Fmag) is applied to the valve due to a command current, which makes the spool of the valve move to the right. When the spool has been displaced to a certain position, line pressure is applied to the clutch. This pressure is also applied to the rear chamber of the valve so that the valve starts regulating when the pressure in the clutch has reached a force which corresponds to the magnetic force applied.
  • the main advantages of the invention are the space optimization, the price of the valve and the reduced number of the valves in the circuit. Furthermore, by reducing the feed back piston valve area, the magnetic force of will be lower for reaching the same pressure level. Finally, the influence of fluid conditions like its temperature will be much lower and the fill time can be reduced drastically.
  • a comparison of the system according to the prior art and the system of the invention shows that the fill time is reduced by 21 %. This fill time reduction is possible due to the fact that there is no offset in the valve.
  • the low hysteresis spring tends to bring the valve back to its steady state position without any preload or offset.
  • said accumulator comprises an axially moveable disc, a spring and a fixed plate with a central hydraulic opening, the spring pushing said disc against said fixed plate.
  • This accumulator acts as a low frequency filter. Thus, all the high frequencies are cut.
  • To calculate the natural frequency of the valve only the stiffness of the fluid and the valve area have to be taken into account.
  • the return spring is not to be considered for the calculation because of its stiffness in comparison to the hydraulic stiffness.
  • the accumulator is incorporated into the valve body.
  • the hydraulic opening is calibrated in order to optimize the dynamic comportment of the system.
  • FIGURE 1 shows a flow diagram of the proposed device
  • FIGURE 2 shows in detail how the accumulator is integrated inside the pressure regulator.
  • FIGURE 1 shows a flow diagram with the pump 1 and the proposed pressure regulator.
  • the accumulator 2 located behind the spool valve allows to save space and acts in the same way if it were located close to the clutch device.
  • the device for actuating the clutch comprises a controlling and regulating valve 3.
  • the valve can be represented as a cylindrical housing 4 with a spool 5 inside. This spool 5 can be moved axially in the housing 4 by exerting force on its ends.
  • a magnetic force (Fmag) may be applied to it due to a command current and on the rear side of the spool, a pressure force (Fp) may be applied.
  • the housing 4 of the valve 3 has several openings 6, two of which being connected to the atmospheric pressure (EXH, meaning exhaust) , one of which being connected to the low pressure circuit (EXH BACK FD, meaning to exhaust back feed) , two of which being connected to the clutch (CLUTCH) and one of which being connected to the line pressure of the pump (LINE) , the high pressure circuit.
  • the openings 6 are in the following order (seen from the front side) : EXH, EXH BACK FD, CLUTCH, LINE, EXH, CLUTCH.
  • the spool 5 extends from the first EXH to the last EXH opening 6 and can either block the openings with its large diameter parties or allow fluid to pass from one opening 6 to a neighbored opening 6 with its small diameter parties. In the starting position, both the EXH BACK FD and the LINE openings are obstructed by the spool 5.
  • the valve functions as follows: In the beginning, there is no pressure in the clutch. A magnetic force (Fmag) is applied to the valve due to a command current, which makes the spool 5 move to the right. When the spool has been displaced to a certain position, line pressure (LINE) is applied to the clutch (CLUTCH) . This pressure is also applied to the rear chamber 7 of the valve (connected to the CLUTCH) so that the valve starts regulating when the pressure in the clutch has reached a force which corresponds to the magnetic force applied.
  • Fmag magnetic force
  • CLUTCH line pressure
  • This pressure is also applied to the rear chamber 7 of the valve (connected to the CLUTCH) so that the valve starts regulating when the pressure in the clutch has reached a force which corresponds to the magnetic force applied.
  • the diameter at the rear of the valve is reduced in order to need low magnetic forces even when the pressure in the clutch is elevated.
  • the low diameter of the hydraulic opening 9 would cause an instable comportment of the valve in absence of the accumulator
  • the accumulator 2 may be directly integrated in the valve body which simplifies the manufacturing of the valve body.
  • the accumulator can also be considered to add a virtual volume. This will be explained by the following considerations.
  • Km is the mechanical stiffness
  • Kh is the hydraulic stiffness
  • Sac is the surface of the piston of the accumulator.
  • Mbulk is the bulk modulus (compressibility of the fluid)
  • Vfluid is the volume of the fluid.
  • Vvirt Mbulk / Km * Sacc 2
  • Vvirt 14,000 e 5 / 14,000 * ( ⁇ /4 * 0,01 2 ) 2
  • Vvirt 616 cm 3

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Magnetically Actuated Valves (AREA)

Abstract

In a device for actuating a clutch in an automatic transmission, a controlling and regulating valve (3) is directly connected with its rear chamber to the clutch with means for applying a magnetic force on the front side of the valve and the line pressure force on the rear side. The valve is configured such that upon applying a magnetic force on the front side of the valve, the line pressure is applied to the clutch. An accumulator (2) acting as low frequency filter is integrated into the rear chamber (7).

Description

DEVICE FOR ACTUATING A CLUTCH IN AN AUTOMATIC TRANSMISSION
The invention relates to a device for actuating a clutch in an automatic transmission.
In automatic transmissions, the following configuration is used to actuate the clutches: An actuator feed limit valve limiting the pressure to a desired value (e.g. at about 8.5 bar) which is connected to a variable bleed solenoid (VBS) controlling the pressure within the clutch. The VBS which is a very sensitive valve actuates the pressure regulator valve of the clutch. Due to a command current, a control pressure establishes at the output of the VBS thereby alimenting the regulating valve. With this configuration, it is possible to control the pressure close to the clutch.
An inconvenience of this device is the fact that it needs three valves. Further, as the VBS is alimented by the actuator limit valve, its dynamic behavior depends on the properties of the fluid (density, temperature, aeration) and the line pressure, so that the control of the clutch is very sensitive to these conditions.
There exist other configurations with only one pressure regulating valve (pressure regulator spool type from BOSCH for example) , but the spool diameter is small, thereby limiting the flow rate so that these configurations are not suitable for all applications .
Aspects of the present invention seek to diminish the number of valves in the hydraulic circuit and to render the control of the valve less dependent on the working conditions. This object is achieved according to the invention by a device for actuating a clutch in an automatic transmission, wherein a controlling and regulating valve is directly connected with its rear chamber to the clutch with means for applying a magnetic force on the front side of the valve and the line pressure force on the rear side and wherein the valve is configured in that upon applying a magnetic force on the front side of the valve, the line pressure is applied to the clutch and wherein an accumulator acting as low frequency filter is integrated into the rear chamber.
In order to maintain pressure inside the clutch, the rear side of the valve is directly connected to the clutch thereby exposing the valve to the pressure inside the clutch. There are two forces to be supported by the valve: On the one hand side, there is the magnetic force (Fmag), and on the other hand side the pressure force (Fp) . At the regulating point, these two forces are identical because the valve tends to an equilibrium position (this supposes that no leakage appears in the hydraulic circuit between valve and clutch, otherwise with a small leakage a correction on the magnetic force would be necessary to guarantee the clutch pressure) .
The valve functions as follows: In the beginning, there is no pressure in the clutch. A magnetic force (Fmag) is applied to the valve due to a command current, which makes the spool of the valve move to the right. When the spool has been displaced to a certain position, line pressure is applied to the clutch. This pressure is also applied to the rear chamber of the valve so that the valve starts regulating when the pressure in the clutch has reached a force which corresponds to the magnetic force applied. The main advantages of the invention are the space optimization, the price of the valve and the reduced number of the valves in the circuit. Furthermore, by reducing the feed back piston valve area, the magnetic force of will be lower for reaching the same pressure level. Finally, the influence of fluid conditions like its temperature will be much lower and the fill time can be reduced drastically. A comparison of the system according to the prior art and the system of the invention shows that the fill time is reduced by 21 %. This fill time reduction is possible due to the fact that there is no offset in the valve. The low hysteresis spring tends to bring the valve back to its steady state position without any preload or offset.
In a preferred embodiment of the invention, said accumulator comprises an axially moveable disc, a spring and a fixed plate with a central hydraulic opening, the spring pushing said disc against said fixed plate.
This accumulator acts as a low frequency filter. Thus, all the high frequencies are cut. To calculate the natural frequency of the valve, only the stiffness of the fluid and the valve area have to be taken into account. The return spring is not to be considered for the calculation because of its stiffness in comparison to the hydraulic stiffness.
Figure imgf000004_0001
1C — 2
V
The expression above will be cut thanks to the accumulator. In one embodiment of the invention, the accumulator is incorporated into the valve body.
In a still further embodiment of the invention, the hydraulic opening is calibrated in order to optimize the dynamic comportment of the system.
Any person skilled in the art will understand that the design of the accumulator and especially of the hydraulic opening has to be optimized in order to reduce or even eliminate the oscillation amplitudes .
A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which:
FIGURE 1 shows a flow diagram of the proposed device,
FIGURE 2 shows in detail how the accumulator is integrated inside the pressure regulator.
FIGURE 1 shows a flow diagram with the pump 1 and the proposed pressure regulator. The accumulator 2 located behind the spool valve allows to save space and acts in the same way if it were located close to the clutch device.
As can be seen from FIGURE 2, the device for actuating the clutch comprises a controlling and regulating valve 3. The valve can be represented as a cylindrical housing 4 with a spool 5 inside. This spool 5 can be moved axially in the housing 4 by exerting force on its ends. On the front side of the spool, a magnetic force (Fmag) may be applied to it due to a command current and on the rear side of the spool, a pressure force (Fp) may be applied. The housing 4 of the valve 3 has several openings 6, two of which being connected to the atmospheric pressure (EXH, meaning exhaust) , one of which being connected to the low pressure circuit (EXH BACK FD, meaning to exhaust back feed) , two of which being connected to the clutch (CLUTCH) and one of which being connected to the line pressure of the pump (LINE) , the high pressure circuit. The openings 6 are in the following order (seen from the front side) : EXH, EXH BACK FD, CLUTCH, LINE, EXH, CLUTCH. The spool 5 extends from the first EXH to the last EXH opening 6 and can either block the openings with its large diameter parties or allow fluid to pass from one opening 6 to a neighbored opening 6 with its small diameter parties. In the starting position, both the EXH BACK FD and the LINE openings are obstructed by the spool 5.
At the rear end of the spool 5, there is a rear chamber 7 with the second CLUTCH opening in the housing 4. More rearwards, there is a fixed plate 8 with a central hydraulic opening 9. A spring 10 fixed on the housing 4 pushes a disc 11 against the fixed plate 8. The fixed plate 8 with its central opening 9, the spring 10 and the disc 11 form the accumulator which acts as low frequency filter.
As the rear of the valve is directly connected to the clutch (CLUTCH) , a force corresponding to the clutch pressure will be exerted onto the valve so that two forces are applied on the valve: On the front side, the magnetic force (Fmag) and on the rear side, the pressure force (Fp) .
The valve functions as follows: In the beginning, there is no pressure in the clutch. A magnetic force (Fmag) is applied to the valve due to a command current, which makes the spool 5 move to the right. When the spool has been displaced to a certain position, line pressure (LINE) is applied to the clutch (CLUTCH) . This pressure is also applied to the rear chamber 7 of the valve (connected to the CLUTCH) so that the valve starts regulating when the pressure in the clutch has reached a force which corresponds to the magnetic force applied.
The diameter at the rear of the valve is reduced in order to need low magnetic forces even when the pressure in the clutch is elevated. The low diameter of the hydraulic opening 9 would cause an instable comportment of the valve in absence of the accumulator
2 according to the invention which is directly added to the rear chamber 7. It functions like a shock absorber and filters the high frequencies. The accumulator 2 may be directly integrated in the valve body which simplifies the manufacturing of the valve body.
The accumulator can also be considered to add a virtual volume. This will be explained by the following considerations.
Km = Kh * Sac2, wherein
Km is the mechanical stiffness, Kh is the hydraulic stiffness, and Sac is the surface of the piston of the accumulator.
Km = Mbulk / Vfluid * Sacc2, wherein
Mbulk is the bulk modulus (compressibility of the fluid) , and Vfluid is the volume of the fluid.
The equivalent virtual volume (Vvirt) is therefore Vvirt = Mbulk / Km * Sacc2
A numerical application with the following characteristic values
Mbulk = 14,000 bar Km = 14,000 N/m Sacc = π/4 * 0,012
shows that the equivalent virtual volume is
Vvirt = 14,000e5 / 14,000 * (π/4 * 0,012)2 Vvirt = 616 cm3,
whereas the volume behind the valve is only about 1 cm3.

Claims

1. A device for actuating a clutch in an automatic transmission, characterized in that a controlling and regulating valve is directly connected with its rear chamber (7) to the clutch with means for applying a magnetic force (Fmag) on the front side of the valve and the line pressure force (Fp) on the rear side and wherein the valve is configured in that upon applying a magnetic force (Fmag) on the front side of the valve, the line pressure is applied to the clutch (CLUTCH) and wherein an accumulator (2) acting as low frequency filter is integrated into the rear chamber (7) .
2. The device of claim 1, wherein said accumulator (2) comprises an axially moveable disc (11), a spring (10) and a fixed plate (8) with a central hydraulic opening (9), the spring (10) pushing said disc (11) against said fixed plate (8) .
3. The device of claim 1, wherein the accumulator (2) is incorporated into the valve body.
4. The device of claim 2, wherein the hydraulic opening (9) is calibrated in order to optimize the dynamic comportment of the system.
5. A device substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawings .
PCT/EP2008/051859 2007-02-15 2008-02-15 Device for actuating a clutch in an automatic transmission WO2008099005A1 (en)

Applications Claiming Priority (2)

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GB0702968A GB2446599B (en) 2007-02-15 2007-02-15 A clutch in an automatic transmission

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Cited By (1)

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WO2021174521A1 (en) * 2020-03-06 2021-09-10 舍弗勒技术股份两合公司 Built-in magnetic filtration assembly and clutch separation system

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DE19645965A1 (en) * 1995-11-09 1997-05-15 Toyota Motor Co Ltd Control system for automatic transmission
EP0845382A2 (en) * 1996-11-28 1998-06-03 Honda Giken Kogyo Kabushiki Kaisha Clutch control valve of a continuously variable vehicle transmission
DE19959943A1 (en) * 1999-09-22 2001-04-12 Hyundai Motor Co Ltd Line pressure control system for motor vehicle automatic gears combines individual control valves in one unit
US20010052368A1 (en) * 1991-08-19 2001-12-20 Harms Louis C. Proportional pressure control valve
US20070026990A1 (en) * 2005-07-27 2007-02-01 Aisin Seiki Kabushiki Kaisha Oil pressure control apparatus for automatic transmission

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