WO2021013292A1

WO2021013292A1 - Multiple-piece annular piston for a slave cylinder for the hydraulic actuation of a clutch or a brake

Info

Publication number: WO2021013292A1
Application number: PCT/DE2020/100565
Authority: WO
Inventors: Paul Gehrke; Michel Jacky; Fadil Mahracha
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2019-07-25
Filing date: 2020-06-30
Publication date: 2021-01-28
Also published as: DE102019120072A1

Abstract

The invention relates to a fluidic actuating system for the fluidic actuation of at least one clutch and/or brake device, with an annular piston which delimits a fluid pressure chamber in an annular chamber. In order to simplify the production of the fluidic actuating system, the annular piston comprises at least one first piston body (11) and a second piston body (12) which changes its position relative to the first piston body (11) in the case of fluid pressure loading of the fluid pressure chamber (7) in such a way that a sealing gap (13) between the second piston body (12) and a housing surface (14) is minimized.

Description

MULTI-PIECE RING PISTON FOR A SLAVE CYLINDER TO THE HYDRAULIC

APPLYING A CLUTCH OR BRAKE

The invention relates to a fluidic actuation system for fluidically actuating at least one clutch and / or braking device, with an annular piston which delimits a fluid pressure space in an annular space.

From the German patent application DE 10 201 1 009 022 A1 a concentric slave cylinder is known, which has a spring cup and a pressure divider, which is characterized by a plurality of compression springs arranged on the outer circumference of the slave cylinder for applying a preload to a release bearing that can be actuated by the slave cylinder are. From the German patent application DE 10 201 1 081 298 A1 a slave cylinder (CSC) is known, in particular for a hydraulic release system of a friction clutch of a motor vehicle, with a substantially concentric slave cylinder housing with a longitudinal axis, wel ches has an annular space to form an annular pressure chamber , in which an annular piston, which is provided with a seal on the pressure chamber side, is guided axially displaceably, the annular piston acting on a release bearing and at least one elastic and / or resilient element is arranged on the slave cylinder housing in the direction of the release bearing, which compensates for tolerances Nem stop of the slave cylinder housing for the release bearing in a rear end position (minimum extension) of the annular piston. A hybrid module for a drive train of a motor vehicle is known from the German Offenle application DE 10 2017 127 102 A1.

The object of the invention is to simplify the production of a fluidic actuation system for the fluidic actuation of at least one clutch and / or brake device, with an annular piston which delimits a fluid pressure space in an annular space. The object is achieved in a fluidic actuation system for fluidic actuation of at least one clutch and / or brake device, with an annular piston that delimits a fluid pressure chamber in an annular space, in that the annular piston comprises at least one first piston body and a second piston body, which is its The position relative to the first piston body is changed when fluid pressure is applied to the fluid pressure space so that a sealing gap between the second piston body and a housing surface is minimized. The annular piston is preferably a slave piston in a concentric slave cylinder. Such concentric slave cylinders are also referred to with the English terms Concentric Slave Cylinder, CSC for short. The annular piston in the claimed concentric actuation system preferably has a relatively large diameter, which is in particular fifty to one hundred millimeters in size. In the case of such large annular pistons, the preferably two-part design of the annular piston with a first piston body and a second piston body has proven to be particularly advantageous. As a result of the two-part design of the annular piston, in particular a relatively large gap between the annular piston and the housing surface that results from an undesired gap extrusion can be minimized. This advantageously prevents an undesired failure of a seal associated with the annular piston.

A preferred exemplary embodiment of the fluidic actuation system is characterized in that the first piston body is designed as a radially inner ring body and the second piston body is designed as a radially outer ring body. The two Kol benkkörper are preferably designed as a closed ring body. Depending on the implementation, it could also be advantageous to carry out at least one of the ring bodies, preferably the radially outer ring body, at least partially slotted.

Another preferred exemplary embodiment of the fluidic actuation system is characterized in that the piston bodies have sliding surfaces with which the piston bodies bear against one another and with which the piston bodies slide against one another when fluid pressure is applied to the fluid pressure chamber. It is particularly advantageous for only the second piston body to slide relative to the first piston body. As a result of this desired sliding movement under the application of fluid pressure, one of the piston bodies, in particular the radially outer ring body, which represents the second piston body, so that the sealing gap between the second piston body and the housing surface is minimized.

Another preferred embodiment of the fluidic actuation system is characterized in that the sliding surfaces, viewed in a cross section through the piston bodies, are arranged at an angle obliquely to a longitudinal axis, parallel to which the annular piston can be moved back and forth. The longitudinal axis defines an axial direction of movement of the annular piston when the fluidic actuation system is in operation. Axial means in the direction of or parallel to the longitudinal axis of the annular piston. Analog means radially transverse to the longitudinal axis. The angle between the sliding surfaces and the longitudinal axis is forty-five degrees, for example. Depending on the design, the angle can be larger or smaller than forty-five degrees to set a desired expansion behavior of one of the piston bodies, in particular the second piston body, which is designed as a radially outer ring body, in terms of size and / or strength.

Another preferred embodiment of the fluidic actuation system is characterized in that the second piston body is formed from an elastic mate rial that enables a desired deformation when the second piston body changes its position relative to the first piston body when fluid pressure is applied to the fluid pressure chamber. The elastic material makes it possible for the second piston body to expand sufficiently relative to the first piston body to minimize the sealing gap. For this purpose, the second piston body is advantageously formed from a plastic material. Both piston bodies can be formed from a plastic material at a particularly low cost. The piston bodies are manufactured from the plastic material, for example, in large numbers at low cost using an injection molding process. The two piston bodies are preferably not made of the same material. The first piston body is made of a plastic material reinforced with glass fibers, for example. The second piston body is preferably formed from an unreinforced Kunststoffma material in order to enable the desired elastic deformation of the second piston body during operation. Another preferred exemplary embodiment of the fluidic actuation system is characterized in that the two piston bodies jointly delimit a receiving space for a seal. The seal is used in a manner known per se to seal the fluid pressure chamber. By showing the receiving space for the seal with the two piston bodies, an effective seal between the piston bodies is achieved in a simple manner. This prevents fluid from escaping from the fluid pressure chamber past the sliding surfaces between the piston bodies.

A further preferred exemplary embodiment of the fluidic actuation system is characterized in that the receiving space for captively receiving the seal is designed in the manner of a dovetail. The dovetail-like Ausfüh tion serves to illustrate an advantageous embodiment of a form-locking connection between the seal and the annular piston.

Another preferred exemplary embodiment of the fluidic actuation system is characterized in that the first piston body has a circumferential shoulder for mounting the annular piston on an actuation bearing. The circumferential shoulder advantageously prevents the annular piston from dipping too deep into the fluid pressure chamber.

Another preferred embodiment of the fluidic actuation system is characterized in that the second piston body has a potential contact surface facing the housing surface with depressions radially on the outside, in order to reduce the size of the potential contact surface. The depressions are designed, for example, as annular groove-like depressions. In and of itself, contact between the second piston body and the housing surface during operation of the fluidic actuation system is undesirable due to the associated friction. In the event that contact nevertheless occurs, the effects of the friction between the second piston body and the housing surface can be kept low by reducing the potential contact surface. The invention also relates to an annular piston, a piston body and / or a seal for a previously described fluidic actuation system. The parts mentioned can be traded separately or together in an assembly unit.

The invention optionally also relates to a method for assembling a fluidic actuation system described above. During assembly, in particular the annular piston with the two piston bodies and the seal is combined in one assembly unit.

The invention optionally also relates to a kit for a previously described fluidic actuation system. The fluidic actuation system is used, for example, in a hybrid module for a drive train of a motor vehicle, as is described in the German patent application DE 10 2017 127 102 A1.

Further advantages, features and details of the invention emerge from the following description in which various exemplary embodiments are described in detail with reference to the drawing. Show it:

FIG. 1 shows a schematic representation of a fluidic actuation system for fluidic actuation of a clutch and / or brake device with an annular piston in longitudinal section;

FIG. 2 shows the enlarged illustration of a section II from FIG. 1;

FIG. 3 shows a representation similar to that in FIG. 2 before the application of a

Fluid pressure space with a fluid pressure; and

FIG. 4 shows the same representation as in FIG. 3 after the application of the

Fluid pressure space with the fluid pressure.

In FIG. 1, a fluidic actuation system 1 for fluidic actuation of a clutch and / or brake device 2 is shown in a simplified manner. The fluidic actuation system 1 is preferably operated with a hydraulic medium and can therefore also be referred to as a hydraulic actuation system 1. Just through a coupling and / or braking device 2 indicated by a rectangle is preferably arranged in a drive train of a motor vehicle.

The fluidic actuation system 1 comprises a ring cylinder 3, in which a ring piston 4 with a longitudinal axis 17 is axially movable back and forth. The term axial refers to the longitudinal axis 17 of the annular piston 4, which is preferably rotationally symmetrical. Axial means in the direction of or parallel to the longitudinal axis 17. Analog means radially transversely to the longitudinal axis 17.

The annular piston 4 is coupled to the clutch and / or braking device 2 via an actuation bearing 5, which is likewise only indicated. On its side facing away from the actuating bearing 5, a seal 6 is assigned to the annular piston 4 in a manner known per se. The seal 6 delimits a fluid pressure chamber 7 with the annular piston 4 in an annular space 8 of the annular cylinder 3.

When the fluidic actuation system 1 is actuated, a fluid pressure is applied to the fluid pressure chamber 7. This fluid pressure in the fluid pressure chamber 7 leads to a movement of the annular piston 4 in the axial direction to the right in FIG. This movement of the annular piston 4 is transmitted to the clutch and / or braking device 2 via the actuating bearing 5.

The annular cylinder 3, the annular piston 4 and the actuating bearing 5 together include a central through hole 9. Through the central through hole 9 extends, for example, at least one shaft which is used in the drive train of the motor vehicle to transmit rotation.

The ring cylinder 3 with the ring piston 4 is also referred to as the 10 concentric slave cylinder. In the case of such concentric slave cylinders 10, a sealing gap 13 results radially on the outside between the annular piston 4 and the annular cylinder 3 due to the design.

If the sealing gap 13 becomes too large, it can happen that the seal 6 is pressed into the sealing gap 13 between the annular piston 4 and the annular cylinder 3 due to the fluid pressure in the fluid pressure chamber 7. Then one also speaks of a gap extrusion. This unwanted column extrusion can lead to a failure of the seal 6 and thus to increased leakage up to the total failure of the concentric slave cylinder 10.

In the enlarged illustration of FIG. 2 it can be seen that the annular piston 4 is designed in two parts with a first piston body 11 and a second piston body 12. The geometry of the two piston bodies 11 and 12 is designed in such a way that when the fluid pressure chamber 7 is pressurized, the second piston body 12 is pressed outwards in a radial direction and closes the sealing gap 13, as can be seen from a synopsis of FIGS. 3 and 4 .

The first piston body 11 is designed as a radially inner ring body 11. The radially inner annular body 11 comprises a circumferential shoulder 19 which, as can be seen in FIG. 2, serves to mount the annular piston 4 on the actuating bearing 5. The umlau Fende paragraph 19 is formed radially on the outside of the first piston body 11. Radially inwardly, the first piston body 11 has a circumferential shoulder 26 through which the annular piston 4 is axially movable back and forth in or on the annular cylinder 3. The circumferential shoulder 26 advantageously prevents the annular piston 4 from dipping too deep into the fluid pressure chamber 7.

The second piston body 12 is designed as a radially outer ring body. The two piston bodies 11 and 12 designed as ring bodies have sliding surfaces 15, 16 facing one another. The two piston bodies 1 1, 12 are with their sliding surfaces 15, 16 in sliding contact.

As can be seen in FIG. 2, the sliding surfaces 15, 16 run at an angle obliquely upwards. The angle between the sliding surfaces 15, 16 and the longitudinal axis (17 in Figure 1) has a size of forty-five degrees in the illustrated embodiment.

The size of the angle can advantageously be used to set how far and how lightly or strongly the second piston body 12 expands relative to the first piston body 11 when the fluid pressure space 7 is acted upon by fluid pressure. By the application of fluid pressure, the radially outer ring body, which the second piston benkkörper 12 represents, pressed in the radial direction outward and tet expanded.

In Figure 3, the detail from Figure 2 is shown before the fluid pressure chamber 7 is applied. The sealing gap 13 is relatively large. FIG. 4 shows that the second piston body 12 has been displaced radially outward relative to the first piston body 11 by the fluid pressure in the fluid pressure chamber 7, so that the sealing gap 13 is minimized.

The two-part design of the annular piston 4 particularly advantageously enables the use of plastic materials for positioning the annular piston 4, specifically particularly advantageously even with large piston diameters, for example fifty to one hundred millimeters. A plastic injection molding process can advantageously be used to position the annular piston 4, in particular the piston body 11 and / or 12. Filigree seal rings, as used in conventional annular pistons, can be omitted.

In Figure 2 it can be seen that the two piston bodies 1 1 and 12 together define a receiving space 18 for the seal 6. The receiving space 18 is designed to lose the seal 6 dovetail-like. The resulting form fit prevents the preassembled seal 6 from coming loose before or during the assembly of the annular piston 4. In addition, the seal 6 in the receiving space 18 prevents fluid from escaping from the fluid pressure space 7 between the sliding surfaces 15, 16.

In FIG. 2 it can also be seen that a potential contact surface 20 of the second piston body 12, which faces the housing surface 14, is equipped with annular groove-like depressions 21 to 24. The groove-like depressions 21 to 24 serve to reduce the potential contact surface 20. This minimizes any friction that may occur when the second piston body 12 comes into contact with the housing surface 14 with its potential contact surface 20. During assembly, the two piston bodies 11, 12 are advantageously pre-assembled with the seal 6 in an assembly unit 25. This assembly unit 25 is then assembled in the ring cylinder 3 during assembly of the fluid actuation system 1.

Reference list

fluidic actuation system

Clutch and / or braking device

Ring cylinder

Ring piston

Actuator bearing

poetry

Fluid pressure space

Annulus

central through hole

concentric slave cylinder

first piston body

second piston body

Sealing gap

Housing area

Sliding surface

Longitudinal axis

Recording room

paragraph

Contact area

deepening

Assembly unit

paragraph

Claims

1. Fluidic actuation system (1) for fluidic actuation of at least one clutch and / or brake device (2), with an annular piston (4) which delimits a fluid pressure chamber (7) in egg nem annular space (8), characterized in that the Ring piston (4) comprises at least one first piston body (11) and a second piston body (12) which changes its position relative to the first piston body (11) when fluid pressure is applied to the fluid pressure chamber (7) so that a sealing gap (13) between the second piston body (12) and a housing surface (14) is minimized.

2. Fluidic actuation system according to claim 1, characterized in that the first piston body (11) are designed as a radially inner ring body and the second piston body (12) as a radially outer ring body.

3. Fluidic actuation system according to one of the preceding claims, characterized in that the piston bodies (11, 12) have sliding surfaces (15, 16) with which the piston bodies (11, 12) bear against one another and with which the piston bodies (11, 12) slide against one another when fluid pressure is applied to the fluid pressure space (7).

4. Fluidic actuation system according to claim 3, characterized in that the sliding surfaces (15, 16), viewed in a cross section through the piston bodies (11, 12), are angeord net at an angle obliquely to a longitudinal axis (17), parallel to which the annular piston (4) can be moved back and forth.

5. Fluidic actuation system according to one of the preceding claims, characterized in that the second piston body (12) is formed from an elastic's material which enables a desired deformation when the second piston body (12) is in its position relative to the first piston body (11 ) changed when fluid pressure is applied to the fluid pressure chamber (7).

6. Fluidic actuation system according to one of the preceding claims, characterized in that the two piston bodies (11, 12) together delimit a receiving space (18) for a seal (6).

7. Fluidic actuation system according to claim 6, characterized in that the receiving space (18) for captively receiving the seal (6) is designed like a dovetail.

8. Fluidic actuation system according to one of the preceding claims, characterized in that the first piston body (11) has a circumferential shoulder (19) for mounting the annular piston (4) on an actuating bearing (5).

9. Fluidic actuation system according to one of the preceding claims, characterized in that the second piston body (12) has a potential contact surface (20) facing the housing surface (14) radially on the outside with recesses (21 -24) to the size of the potential contact surface (20) to zoom out.

10. annular piston (4), piston body (11, 12) and / or seal (6) for a fluidic actuation system according to one of the preceding claims.