WO2009149997A1

WO2009149997A1 - Central disengaging element for actuating a vehicle clutch

Info

Publication number: WO2009149997A1
Application number: PCT/EP2009/055579
Authority: WO
Inventors: Karl-Fritz Heinzelmann; Christoph RÜCHARDT; Thomas JÄGER
Original assignee: Zf Friedrichshafen Ag
Priority date: 2008-06-12
Filing date: 2009-05-08
Publication date: 2009-12-17
Also published as: DE102008002379A1

Abstract

The invention relates to a central disengaging element (1) for a pressure-medium actuated vehicle clutch, wherein the central disengaging element (1) is arranged coaxially with respect to a transmission input shaft (2) and comprises at least one pressure chamber (4) which, when pressurized, actuates the vehicle clutch via an axially displaceable disengagement bearing (3). The at least one pressure chamber (4) is formed by at least two diaphragm bellows (5, 8) having a cover (7, 8) connected in a pressure medium-tight manner at each end of the diaphragm bellows (5, 6).

Description

Central release button for actuating a vehicle clutch

The present invention relates to a Zentralausrücker for a Fahrzeugkuppiunc the preamble of the claim

Actuator actuators have several advantages. towards less space. The transmission is more compact and lighter. Furthermore, the release force of the Zentraf trigger can be changed without additional support and additional storage! in, whereas in the case of external ^"" idern in deflection mechanics deflecting and Kontaktste are necessary. Each of these deflection and contact points causes friction and play, and is more likely to affect the control quality of the clutch. In addition, in a zentra arranged releaser usually the actuators through the

Igor, lausrückers possible over the life of the vehicle because a

Repair or a ni:

return force generated by means of piston, which is displaceable in a ringförmi conditions pressure chamber ι. The pressure chamber is beaufschiagbar with a pressure medium and usually sealed by Koibendichtringe which are shifted axially when operating the along the pressure chamber wall. DE 19716473 A1. There is explained in the introduction to the introduction that the formation of the peripheral surfaces of the pressure chamber designed as a sealing surfaces for Ren Riπgkoiben with good dynamic tightness properties ais difficult. In DE 19716473 A1 it is therefore proposed to use a pressure

faπgsfiäche the Riπgkolbeπ tightly rests. In addition, a bellows made of plastic ensures that the Ringkoiben and the adjacent components are not contaminated from the outside.

However, it has been found that, despite considerable technical effort, it is scarcely possible to keep the annular pressure chamber free of leaks over the entire service life of the piston. In addition to the production-related roughness of the sealing surfaces lead corrosion during operation and impurities that come from the outside and / or via the pressure medium to the sealing surfaces, to a wear of the seals and thereby leaks. The roof areas and seals are also exposed to high temperature fluctuations, which increases the leakage even more. Low temperatures can lead to vitrification of the seals and / or spall fatigue at the sealing surfaces. High temperatures increase the susceptibility to wear and reduce the resistance to aging, in particular of plastic parts such. Sealing rings.

However, leaks at the sealing surfaces between the annular piston and the peripheral surfaces of the pressure chamber are problematic for the safe operation of the coupling device and of the vehicle. Such leaks can cause one through the pressure center! open clutch tapers independently, which in an engaged gear to an unwanted start of the In hydraulic systems, loss of hydraulic fluid can result in total failure of the clutch actuation and stalling of the vehicle due to lack of sufficient hydraulic fluid in the system. Also, leaks in a hydraulic clutch actuation system can contaminate parts of the clutch such that the clutch slips and the vehicle therefore remains lying.

In a pneumatic system, leakages increase the air consumption and thus the energy consumption of the vehicle and adversely affect the valve actuation of pneumatic control valves.

Another disadvantage of the described known embodiments of Zentralausrückern is caused by friction on the seals between the annular piston and the peripheral surfaces of the pressure chamber. As a result, in particular with pneumatic piston-cylinder units, stick-Siip effects, which become noticeable when the clutch is actuated, and the

The present invention has for its object to provide a wear-free and low-maintenance, pressure-medium-actuated Zentraiausrücker that despite a simple structure ermögiϊcht a long-term reliable operation with high control quality.

This object is achieved by a Zentralausrücker with the features of claim 1. Advantageous developments are described in the dependent claims.

The invention Zentraiausrücker is arranged coaxially to a gear eiπgangswelie and comprises at least one pressure chamber which actuates the vehicle clutch when pressurized via an axiai displaceable release bearing. The at least one pressure chamber is characterized by At least two diaphragm bellows with a pressure-tight sealing lid connected to each diaphragm bellows formed at each end of the at least two diaphragm bellows, so that a pressure medium-tight pressure chamber is present, pressure medium tight means gas-tight in the case of a pneumatic system, In the case of a hydraulic system, the connection must be tight in relation to the hydraulic

When pressure is applied to the pressure chamber, the diaphragm bellows and with them the pressure chamber expand in the axial direction and displace the release bearing in the desired axial direction, so that the vehicle coupling is actuated. If the pressure in the pressure chamber drops, then the pressure chamber contracts in the axial direction and the release bearing

The term membrane bellows in this document single or multi-walled, pressure-tight, one-piece or consisting of several rigidly interconnected parts hollow body understood that expand when pressurized their interior, in particular in the axial direction. This includes both Membraπbalgen, the wall of annular, paired at the inner and outer diameter, z. B. welded membranes exists, as well as bellows of a tubular body with a wave-shaped wall, for example, made of a hydraulically pressed tube

The proposed Zentralausrücker is fundamentally suitable for press-closed and pressure-opened couplings. With the pressure-locked clutch, the clutch is engaged with increasing pressure in the pressure chamber, so that a torque is transmitted. With pressure-open clutches, the clutch is disengaged with increasing pressure in the pressure chamber, so that no torque is transmitted, By avoiding a shift between two adjoining components, as is customary in the prior art between a piston and a Zyiinderwand, the Probieme described above with the tightness in the Zentralausrücker invention are not present. This allows a life-long, maintenance-free function of the central release. Also stick-SIip effects, as they have occurred in conventional Zentralausrückern during movements between piston seals and cylinder wall, there is not in the Zentralausrücker invention, thus the control performance of the actuator is improved.

Preferably, the pressure chamber is formed from two diaphragm bellows with different diameters arranged coaxially with the transmission input shaft and at each end of the two diaphragm bellows by a diaphragm connected to the diaphragm bellows so that a pressure chamber with an annular cross-sectional area arranged coaxially with the transmission input shaft is formed. The coaxially arranged, annular pressure chamber causes a uniform, symmetrical disengaging force on the release bearing and ensures uniform loading of the diaphragm bellows. This will increase the life of the entire actuator

Another preferred embodiment of the invention provides several, consisting of membrane bellows with lids pressure chambers, which are arranged adjacent to the release bearing in the axial direction. In this case, all the pressure chambers are preferably arranged at the same radial distance from the center axis of the Ausrückiagers and at the same distance from each other in the circumferential direction. For example, four pressure chambers each offset by 90 degrees to each other can be arranged on the release bearing. Since the pressure chambers in this design lie directly on the release bearing and thus inevitably in a central position with respect to the entire clutch are arranged, it is also a Zentralausrücker here.

A preferred embodiment of the proposed Zentralausrückers provides that the diaphragm bellows are welded at their ends to the lids. In this way, a permanently pressure-tight connection between a diaphragm bellows and the covers is formed.

Preferably, the release bearing facing away from the lid is arranged stationary. For example, this cover is rigidly connected to a transmission housing. One or both blankets! can also be formed by an already existing component or be integrally formed therewith. For example, a part of the gear housing or a part of the release bearing can be used as a lid, whereby the number of individual components is reduced.

According to a further preferred embodiment, it is proposed that at least one diaphragm bellows is integrally formed together with at least one of the lids. This design also contributes to the permanent, reliable function of the central release mechanism. In addition, such a configuration of the pressure chamber simplifies its manufacturing and assembly process and

Another aspect of the invention relates to the entire actuation system of the clutch. An important factor for the response and the control quality of the coupling is a sufficiently high bias of the actuator. The achievable life of the release bearing depends on a sufficient biasing force, because it ensures a safe rolling of the rolling elements in the release bearing even in non-actuated operation. A sliding of the rolling elements, which is possible with too little biasing force, reduces the service life of the lubricant and the life of the Ausrucklagers. For these reasons, a biasing spring is provided in conventional actuators, z, B. also in the known from DE 19716473 A1 Zentralausrücker,

The sufficient biasing force can be realized according to a further preferred aspect of the invention in that at least one diaphragm bellows is installed with bias. As a result, the biasing spring is saved and simplifies the structure of the actuating system.

When selecting suitable materials for the diaphragm or bellows, in addition to the mechanical properties, it is important to ensure sufficient temperature resistance and aging resistance of the materials in order to be able to ensure the required high service life. Therefore, the membrane bellows are preferably made of metal. Metallic materials, e.g. Steels, have a high temperature resistance and aging resistance and are insensitive to external influences such as dust and other contaminants. In addition, the resilient action of the diaphragm bellows, which is necessary for the above-described function of the diaphragm bellows as a pretensioning spring, can be reliably and reproducibly achieved over a long period of time with a metallic diaphragm bellows.

Furthermore, however, diaphragm bellows are also used, which are made of plastic, wherein the plastic may be fiber-reinforced, for example. Also reinforced with metal rings membrane or bellows made of plastic can be used in the Zentralausrücker invention.

A further preferred embodiment of the invention provides that the pressure chamber through a bore in the stationarily arranged lid, a pressure medium can be supplied. The connection to a supply system of the pressure medium is easiest if the pressure medium connection to a local fixed component is arranged, because so no flexible and thus maintenance-prone Druckmiefelitungen are needed.

Preferably, a variable-length sleeve is arranged around the outer membrane bellows. This sleeve is variable in length to compensate for the disengagement of the pressure chamber can. The sleeve may be formed, for example, telescopically. The sleeve protects the outer diaphragm bellows against contamination from the outside and can additionally serve as a support element for the diaphragm beam, so that the outer diaphragm bellows can not escape in the radial direction. It is also conceivable to arrange another such sleeve radially inside the diaphragm bellows arranged inside. Such a sleeve arranged between the inner diaphragm and the transmission input shaft protects the inner diaphragm from contamination and can serve as a supporting element for the inner diaphragm bellows.

Another embodiment of the present invention is characterized in that the pressure chamber is formed by a toroidal bellows. The bellows expands when pressurized and thus causes the disengagement to the release bearing.

The toroidal bellows can be designed, for example, by different wall thicknesses or material properties in certain areas of the bellows so that it expands when pressurized preferably in one direction, namely in the direction of its central axis. The direction and the extent of the disengagement of the bellows when pressurized can also be by appropriate tissue deposits in a elastic Grundmateria! of the bellows. Likewise, it is conceivable to reinforce the toroidal bellows with fabric inserts, which admittedly allow a sufficient expansion of the bellows for the disengagement, but limit further expansion, so that overstressing or damage of the bellows is prevented by the pressurization. Such a bellows can be produced inexpensively in one step as a one-piece component and is preferably made of elastic material. A one-piece bellows ensured with a suitable choice of material absolute tightness against the pressure medium.

Two preferred embodiments of the invention are explained below with reference to the drawings. Show it:

Fig. 1 shows a first inventive Zentπalausrücker with

Fig. 2 eir adjacent components in a schematic Schnsttdarstellung and

Fig. 3 is a schematic Schnittdarstelüung the Zentralausrückers from: iq, 2 with

The central release 1 shown in Fig. 1 consists essentially of an outer diaphragm bellows 5 and an inner diaphragm bellows 8 and the two covers 7 and 8. The diaphragm bellows 5, 6 and the cover 7, 8 are coaxial with each other and the central axis 9 a Transmission input 2 and a release bearing 3 is arranged. The two diaphragm bellows 5 and 8 are welded gas-tight at their two ends to the covers 7 and 8, so that the pressure-tight pressure chamber 4 is formed in the interior. The pressure chamber 4 can be acted upon by compressed air via a pressure connection 11 and through a bore 10 in the cover 8. The lid 8 is rigidly attached to a transmission housing 12. The cover 7 is integrally formed in the illustrated embodiment with a part of the release bearing 3, ie the facing cover plate of the release bearing for the The release bearing 3 is axially displaceable and arranged coaxially to the transmission eingaπgswelte 9 and acts via a voltage applied to the release bearing 3 plate spring 13 on an operatively connected to the Teüerfeder 13, not shown, pressure plate of the clutch. Suitable designs and arrangements of the other coupling side and their function are well known and therefore not shown and described here.

The following describes the function of the central release 1 for a pressure-opening clutch, without the invention limiting itself to this type of clutch operation.

To disengage the clutch, the pressure chamber 4 is acted upon via the bore 10 with compressed air. The pressure in the pressure chamber 4 causes expansion of the diaphragm bellows 5 and 8 in the axial direction. Since the diaphragm bellows 5 and 6 are fixed at its end facing away from the Ausπücklager 3 stationary on the gear housing 12, they move the voltage applied to the other end release bearing 3 axially in the direction of the plate spring 13. Thus, the plate spring 13 is deformed so that a not shown, with the plate spring 13 is actively connected pressure plate of the clutch is lifted from a Mitnehmerschei- and the torque transmission from a driven by the drive motor of the vehicle width on the transmission input shaft. 2

As long as a sufficiently high pressure is applied to the air port 11 and thus in the pressure chamber 4, the clutch remains disengaged, ie opened. When the pressure in the pressure chamber 4 drops, the Membranbaigen 5, 8 pull back together and the release bearing 3 moves axially in the direction of the transmission. As a result, the clutch is engaged again, so that after a certain engagement again a torque transmission between the drive motor and the transmission input shaft 2 takes place. This one backward movement is assisted by the tiller spring 13, which is thereby

The sleeve 14 protects the IVfemb- ranbalg 5 disposed within the sleeve 14 from contamination from the outside, a first cylinder jacket-shaped part of the two-part sleeve 14 is rigid with the fixed ceiling! 8, a second, cylinder jacket-shaped part of the sleeve 14 is rigidly connected to the axially movable release bearing 3. The free ends of the first and the second part of the sleeve 14 overlap in the central region of the diaphragm bellows 5. During disengagement and engagement movements of the release bearing 3, the first and the second part of the sleeve 14 telescope into one another. The overlap of the two parts of the sleeve 14 is designed so that at maximum disengagement of the clutch is still a complete coverage of the diaphragm bellows present 5 and a safe nesting

The embodiment shown in FIGS. 2 and 3 differs from FIG

Each of these pressure chambers 41, 42, 43 and 44 is formed by a diaphragm bellows 51, 52, 53 and 54, which on each end face with a common cover 7, 8 for all four Membranbaigen 51, 52, 53 and 54 is sealed. The four diaphragm bellows 51, 52, 53 and 54 are all of the same construction and dimensions.

1 ZL

Cover plate of Ausrückiagers 3 at the same time 41, 42, 43 and 44. On the gegenüberliec ite the m 51, 52, 53 and 54, a common cover 8 for all four 41, 42, 43 and 44 is provided. The embodiment shown in Fig. 2, in addition to the arranged outside the diaphragm bellows sleeve 14, a sleeve 16 which is disposed within the diaphragm bellows. The sleeve 16 protects the membrane bellows 51, 52, 53, 54 against contamination from the inside. A first cylindrical shell-shaped part of the two-part sleeve 16 is rigid with the fixed ceiling! 8 connected. A second, cylinder jacket-shaped part of the sleeve 16 is rigidly connected to the axially movable release bearing 3. The free ends of the first and the second part of the sleeve 16 overlap in the central region of the diaphragm bellows 51, 52, 53, 54. During disengagement and engagement movements of the release bearing 3, the first and the second part of the sleeve 16 telescope into one another. The overlap of the two parts of the sleeve 16 is designed so that at maximum disengagement of the clutch is still a complete coverage of the diaphragm bellows 51, 52, 53, 54 for snnenfe- genden Getriebeeingangsweile 2 out, and that a secure telescoping is guaranteed.

As can be seen in the sectional drawing A - A in Fig. 3, the four pressure chambers 41, 42, 43 and 44 are evenly distributed, i. Offset in the circumferential direction in each case by 90 degrees, with radially the same distance from the central axis of the release bearing 3. Likewise, an arrangement of three pressure chambers with a displacement of 120 degrees in the circumferential direction is possible.

To actuate the vehicle clutch, the pressure chambers 41, 42, 43 and 44 via the air port 11, the bore 10 and the Ringka na! 15 pressurized air. Consequently, the identical pressure chambers 41, 42, 43 and 44 expand evenly in the axial direction and the clutch is actuated via the release bearing 3. Instead of the annular channel 15, each of the pressure chambers 41, 42, 43 and 44 may be provided separately with an air connection. The claimed and described embodiments are applicable in pneumatic or hydraulic form. In pneumatic systems, designs are also conceivable in which the use of negative pressure increases the control speed and extends the control possibilities. For this purpose, the at least one pressure chamber 4 can be acted upon by the described air connection 11 with negative pressure or it is an additional

Release bearing pressure chamber

Cover central axis

Air connection gearbox

Sleeve ring sleeve

pressure chamber

ig

Claims

1. Zeπtralausrücker for a pressure-medium-actuated vehicle clutch, wherein the Zentralausrücker is arranged coaxially to a transmission input shaft and at least one pressure chamber which at DruckbeaufscNa- supply the vehicle clutch via an axially displaceable release bearing (3) actuated, characterized in that the at least one pressure chamber (4 ) by at least two diaphragm bellows (5, 6, 51, 52, 53, 54) with a pressure medium tightly connected to the diaphragm bellows (5, 6) ceiling! (7, 8) is formed at each end of the membrane strips (5, 6, 51, 52, 53, 54),

2. Zentralausrücker according to claim 1, characterized in that the pressure chamber (4) of two coaxial with the transmission input shaft (2) arranged diaphragm bellows (5, 6) with different diameters and by a pressure medium tight with the diaphragm bellows (5, 6) associated lid ( 7, 8) is formed at each end of the two diaphragm bellows (5, 8), so that a coaxially to the Getriebeeiπgangswelte (2) arranged pressure chamber (4) is formed with an annular cross-sectional area.

3. Zentralausrücker according to claim 1, characterized in that a plurality of pressure chambers (41, 42, 43, 44) in the axial direction on the release bearing (3) are arranged fitting, wherein each of the pressure chambers (41, 42, 43, 44) of a diaphragm bellows (51, 52, 53, 54), each with a pressure medium tightly connected to the diaphragm bellows cover (7, 8) at each end of the diaphragm bellows

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4. Zentralausrücker according to claim 3, characterized in that the pressure chambers (41, 42, 43, 44) are arranged at the same radial distance from the central axis of the release bearing (3) and at the same distance from one another in the circumferential direction.

5. Zentralausrücker according to any one of the preceding claims, characterized in that the at least one diaphragm bellows (5, 6) at its ends with at least one blanket! (7, 8) is welded,

6. Zentralausrücker according to any one of the preceding claims, characterized in that the release bearing (3) facing away from ceiling! (8th)

7. Zentraüausrücker according to any one of the preceding claims, characterized in that at least one of the ceiling! (7, 8) by an existing component of the components adjacent to the central release.

characterized in that at least one diaphragm bellows (5, 6) together with

characterized in that at least one membrane bellows (5, 6) is arranged and installed with bias in such a way that the membrane strip (5, 6) biases the actuating device of the coupling in the sense of a biasing spring.

10, Zentralausrücker according to any one of the preceding claims, characterized in that at least one fviembranbaig (5, 6) is made of metal.

11. Zentralausrücker according to any one of the preceding claims, characterized in that the at least one pressure chamber (4, 41, 42, 43, 44) through a bore (10) in one of the cover (7, 8), a pressure medium can be fed.

12, Zentralausrücker according to one of the preceding characterized in that one, the at least one membrane bellows (5) length-adjustable Hüise (11) is provided.

13. Zentralausrücker for a pressure-medium-actuated vehicle clutch, wherein the Zentralausrücker is coaxial with a Getriebeeir and at least includes a pressure chamber which guπg the vehicle clutch via an axially displaceable release bearing (3)

3t. through a toroidal bi

14. Zentralausrücker according to claim 13, characterized in that the bellows consists of elastic material.

15. Zentralausrücker after 14, characterized in the elastic material reinforcing deposits eingea worked.