WO2018019328A1

WO2018019328A1 - Piston-cylinder unit

Info

Publication number: WO2018019328A1
Application number: PCT/DE2017/100596
Authority: WO
Inventors: Geoffroy Petit; Alexandre Chevet; Stephane Rocquet
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2016-07-28
Filing date: 2017-07-19
Publication date: 2018-02-01
Also published as: DE102016213904A1; DE102016213904B4; DE112017003750A5

Abstract

The invention relates to a piston-cylinder unit, in particular a slave cylinder (9) of a disengagement system for a clutch system or brake system of a motor vehicle, comprising a housing (12), which is arranged concentrically around a transmission input shaft and which has a radially outer cylinder wall (13) and a radially inner cylinder wall (14), between which a pressure chamber (15) is formed and an annular piston (5) is axially movably arranged, to which piston a pressure medium can be applied and which piston is operatively connected to a throw-out bearing (16), wherein the stroke of the piston (5) is limited in the direction toward the throw-out bearing (16) by a stop region (17.4), which is formed on a stop ring (17), which is arranged on the inner cylinder wall (14), wherein, according to the invention, the stop ring (17) has a flange (17.1) pointing radially outward, with shaped elements (17.5) pointing toward the end face (14.1) of the inner cylinder wall (14).

Description

Piston-cylinder unit

The invention relates to a piston-cylinder unit, in particular a slave cylinder of a release system for a clutch or brake system of a motor vehicle according to the preamble of the first claim.

Generic concentric slave cylinders (CSCs) or central disengagements are used in hydraulic clutch systems in the functional chain between the clutch pedal and the clutch, thus hydraulically assisting the slave cylinder based on hydraulic fluid flowing from a master cylinder into the slave cylinder to operate a clutch of a vehicle.

Generic slave cylinder have designed as a ring cylinder housing, which is arranged around a clutch or transmission input shaft. In the housing, an axially movable annular piston is guided, which acts on a bearing on a clutch release bearing. It must be ensured that during operation of the slave cylinder, the piston can not extend beyond a specified maximum extension. Such overrunning (overpressing) of the piston can be done for example due to temperature fluctuations or volume expansions of the hydraulic medium. Also, by automating vehicles operated with conventional CSC without a displacement sensor using a HCA (Hydrostatic Clutch Actuator), a higher fluid volume is available in the hydraulic clutch system. If the driver overruns the maximum extension, the slave cylinder may be destroyed with consequential damage. The automation also eliminates the sniffer function in the clutch master cylinder (CMC), as a result of which the resulting volume expansion, under the influence of the temperature of the fluid used, induces unintended actuation of the CSC without this being diagnosed. Also in this case, a defect of the concentric slave cylinder or the hydraulic system is the result. To Begien- tion of the stroke is therefore usually - usually on the housing or on the guide sleeve of the slave cylinder - provided a stop on which the piston comes into abutment in an end position.

DE 10 2015 220 819 A1 describes a piston-cylinder unit, the stop sleeve is in operative connection with the guide sleeve by means of radially outwardly facing mold elements in such a manner that the outer diameter of the stop sleeve with the form elements larger as the inner diameter of the guide sleeve. The form elements are preferably formed as radially outwardly bent retaining hooks and / or lugs.

In DE 10 2015 212 716 A1 a piston-cylinder unit is described in which the stop sleeve is assigned a stiffening element. This stiffening element is tubular and arranged within the stop sleeve. Preferably, it is connected to the stop sleeve by means of compression.

In a not yet published patent application, a stop ring is described with radially inwardly facing locking elements which engage in corresponding recesses in the guide sleeve and thus limit a stroke of the piston in the direction of the release bearing.

Another patent application, not yet published, describes a slave cylinder having a housing made of plastic material concentrically disposed about a transmission input shaft and having an axially movable annular piston which can be acted upon by a pressure of a pressure medium and is operatively connected to a release bearing, wherein the housing a stop is provided which limits a stroke of the piston in the direction of the release bearing. The abutment consists at least partially of a metallic sleeve and / or of a second plastic material that differs from the plastic material of the main body of the housing or interacts with it.

By acting in the direction of the release bearing force of the piston, it may happen that the stop, which is provided to limit the piston stroke, undesirably deformed.

The object of the invention is therefore to provide a piston-cylinder unit which ensures a reliable Kolbenhubbe- limitation, especially at high pressures in the stop position with a simple constructive and manufacturing engineering structure.

This object is achieved with the characterizing features of the first claim. Advantageous embodiments emerge from the subclaims.

The piston-cylinder unit is formed in particular in the form of a slave cylinder with a concentrically arranged around a transmission input shaft housing having a radially outer cylinder wall and a radially inner cylinder wall, between which a pressure chamber formed and acted upon by a pressure medium and with a release bearing in operative connection standing annular piston is axially movable angeoid- net, wherein the stroke of the piston is limited in the direction release bearing by a stop area, which is arranged on a at one end face of the inner cylinder wall Stop ring is formed and wherein the stop ring according to the invention has a radially outwardly facing flange with pointing in the direction of the end face of the inner cylinder wall form elements.

In this case, a stop ring can be used, which serves to apply a bias to the piston or the support in the return movement and does not deform undesirable in an axial force of the piston. For this purpose, the stop ring may have a peripheral wall region bent in the direction of the piston, on which the stop region is formed. The mold elements are formed in a radially outwardly facing flange of the stop ring and are preferably on the front side of the inner cylinder wall.

In particular, the form elements are formed as mutually spaced bulges of the stop ring. Alternatively, the mold elements can also be attachments welded or otherwise fastened to the stop ring, which for example are nose-shaped. The mold elements are in particular on the end face of the inner cylinder wall, while located between the individual form elements areas of the flange, which are spaced from the end face of the inner cylinder wall.

Preferably, the stop ring has a substantially parallel to the travel path of the Kd bens lying on the end face of the stop area is arranged. The stop region of the stop ring protrudes in particular at least partially radially outwardly beyond the end face or the outer diameter of the inner cylinder wall and forms an axial stop for the piston.

In particular, the mold elements have a convex shape in the direction of the inner cylinder wall. In this case, it is possible for a contact area of the form elements to be flattened, and thereby the contact surface on the front side of the inner cylinder wall is increased.

Preferably at least 4, in particular at least 8 form elements are regularly distributed over the flange of the stop ring.

Advantageously, the stop ring is provided with a flange which tapers radially inwards against the flange and extends essentially axially, with which it is received in the inner diameter of the inner cylinder wall.

Preferably, the collar of the stop ring has an outer diameter which is smaller than the inner diameter of the inner cylinder wall and at the collar a bead reaching down to the inner diameter of the inner cylinder wall in the manner of an annular bead is hidded, which is supported on the inner diameter of the inner cylinder wall. The inner cylinder wall preferably has at its end a radially inwardly pointing collar, via which the stop ring is in operative connection with its bead and forms an axial stop and thus a pull-out protection for the stop ring. If the button is then moved in the direction of the release bearing, it will eventually hit the stop area of the stop ring with its end face and thus exert a force on the stop ring. This rests with its bead on the collar of the inner cylinder wall and thus limits the stroke of the piston in the direction of the release bearing.

Instead of an inner cylinder wall and a separate guide sleeve can be arranged radially inside lying in the slave cylinder.

The stop ring can be made for example of plastic or a metallic material. Preferably, the stop ring is made by machining or as a sheet metal part.

Advantageously, a reliable Kolbenhubbegrenzung is ensured by the inventive arrangement, especially at higher pressures of more than 10 bar.

The invention will be explained in more detail with reference to an embodiment and associated drawings, without being limited to these. Show it:

FIG. 1 is a schematic diagram of a clutch actuation system;

FIG. 2 shows a schematic illustration of a stop ring according to the prior art,

3 and 4 show a three-dimensional view of the stop ring according to the invention,

FIG. 5 shows the section A-A according to FIG. 3,

Figure 6: the section through a slave cylinder according to the invention with stop ring; FIG. 7: detail B according to FIG. 6.

FIG. 1 shows a schematic diagram of a clutch actuation system 1. An abutment device 2 acts on the encoder side 3 on a master cylinder 4. In this case, a piston 26 on the top side of the master cylinder 4 is moved along an actuator path (to the right in this illustration), whereby the volume of the hydraulic fluid 6 contained in the master cylinder 4 changed and a pressure in the master cylinder 4 is built, which is transmitted via a hydraulic line 7 to the slave side 8 of the clutch actuating system 1. The hydraulic line 7 is connected to a slave cylinder 9, which is a release system and is formed on the slave side 8 of the clutch actuation system 1. On the slave side 8 causes the pressure of the hydraulic fluid 6 in the Nehmerzy- 9, a change in travel of a piston 5, which is transmitted to a clutch 10 to actuate these. The piston 5 of the slave cylinder 9 is axially movably mounted in a housing 12 designed as a double-walled cylinder. The housing 12 has an outer cylinder wall 13 and an inner cylinder wall, not shown, which enclose a non-designated pressure chamber. The piston 5 of the slave cylinder 9 is actuated in the pressure chamber when a pressure in the pressure chamber of the slave cylinder 9 is built up. As a result, a release bearing (not represented here), which is in operative connection via springs with a coupling 10, is moved to actuate the coupling 10.

2 shows a schematic diagram of a variant of a stop ring 17 according to the prior art. The stop ring 17 is located on the end face of the inner cylinder wall 14 of a slave cylinder and has circumferentially on a radially outwardly facing flange 17.1. The flange 17.1 projects radially beyond the outer diameter of the inner cylinder wall 14 and forms with its end region a stop region for the Kd- ben 5. The piston 5 is pressed with a force F in the direction of an unillustrated release bearing and presses against the flange 17.1. In a trained according to the prior art stop ring 17, the flange 17.1 is undesirably bent or deformed even at relatively low pressures from 10 bar.

Figures 3 and 4 show a three-dimensional view of the stop ring 17. The wall portion 17.3 of the stop ring 17 is bent substantially parallel to the travel of a piston, not shown here and has the end face the stop area 17.4 for the piston, not shown here. Distributed uniformly over the catch, the stop ring 17 has, in a radially outwardly pointing flange 17.1, a plurality of form elements 17.5 designed as formations, which serve as contact surfaces for an inner cylinder wall (not shown). At its axially extending to the inner cylinder wall, not shown, which serves for Aufnahe on the inner cylinder wall (see also Figure 7), the stop ring 17 has a circumferential bead 17.2, which is axially supported on a collar of the inner cylinder wall, not shown.

FIG. 5 shows a section A-A according to FIG. 3 through the stop ring 17. The sectional plane A-A thereby leads through two form elements 17.5 which are opposite one another on the flange 17.1 of the stop ring 17. It can be seen that the depth T of the form elements 17.5 in the flange 17.1 corresponds to the edge height H of the wall area 17.3.

FIG. 6 shows a section through a slave cylinder 9 according to the invention with a stop ring 17 and in FIG. 7 a detail B according to FIG. 6. The housing 12 of the slave cylinder 9 has a radially outer cylinder wall 13 and a radially inner cylinder wall 14 which has a pressure chamber 15 enclose. Instead of a higher cylinder wall 14 may in the housing 12 may also be arranged a guide sleeve (not shown). The inner cylinder wall 14 has an end face 14.1, on which a radially inwardly directed collar 14.2 is formed (see FIG. 7). Between outer 13 and inner cylinder wall 14, an annular piston 5, which can be acted upon by a pressure medium and is in operative connection with a release bearing 16, is arranged to be axially movable along a longitudinal axis L. The stroke of the piston 5 in the direction of the release bearing 16 is limited by the stop ring 17, which is received at the non-designated inner diameter of the inner cylinder wall 14.

The effective range of stop ring 17 and inner cylinder wall 14 is shown enlarged in Figure 7 as detail B of Figure 6 in detail. The stop ring 17 is located on the end face 14.1 of the inner cylinder wall 14 with the form elements 17.5 of its flange 17.1. The flange 17.1 is bent at its outer periphery with a wall portion 17.3 substantially parallel to the travel of the piston 5. At the end face pointing in the direction of the piston 5, the stop area 17.4 for the piston 5 is formed. The stop region 17.4 of the stop ring 17 protrudes radially beyond the outer diameter of the inner cylinder wall 14, at least in certain regions, and is therefore located in the region of the piston 5. The piston 5 has a shoulder 5.1, through which a contact surface for the stop region 17.4 of the stop ring 17 is formed. The flange 17.1 has a plurality of preferably regularly distributed in the direction of the end face 14.1 of the inner cylinder wall 14 facing mold elements 17.5. These form elements 17.5 engage the front side 14.1 of the inner cylinder wall 14. They are formed as bulges of the stop ring 17. The inner cylinder wall 14 is thus in the axial direction e- only via the mold elements 17.5 with the stop ring 17 in Wrkverbindung. The axially extending along the inner cylinder wall 14 portion 18 of the stop ring 17 has an unspecified outer diameter which is smaller than the inner diameter of the inner cylinder wall 14. The stop ring 17 is further connected to a radially inwardly adjacent to the flange 17.1 collar 17.6 provided with which it is received in the inner diameter of the inner cylinder wall 14. At the axially extending along the inner cylinder wall 14 portion 18 of the stop ring 17 a reaching to the inner diameter of the inner cylinder wall 14 bead 17.2 is formed in the manner of an annular bead, which is supported on the inner diameter of the inner cylinder wall 14.

If the piston 5 is now pressed beyond its regulated travel path in the direction of the release bearing 16, it presses with its end face 5.2 against the release bearing 16 and simultaneously exerts a force on the stop region 17.4 of the stop collar 17 with its shoulder 5.1. The stop ring 17 is supported by the form elements 17.5 and the bead 17.2 on the inner cylinder wall 14 and is thus not plastically deformed even at higher pressures of over 10 bar.

According to an embodiment, not shown, it is also possible that the formations in the flange of the stop ring extend radially into the region of the piston, so that the piston is pressed in a disengagement against the formations.

It is further possible, according to a variant not shown, that the formations are not spaced from each other, but e.g. to wave together.

Preferably, the formations in the flange extend from radially inward to radially outward.

By the form of elements in the flange 17.1 of the stop ring 17, a stiffening of the flange 17.1 is achieved, which counteracts an undesirable plastic deformation when force is applied by the piston 5.

Reinforcing the prevention of plastic deformation of the flange portion of the stop ring by the bent in the direction of the piston 5 wall portion 17, on which the stopper portion 17.4 is formed for the piston 5. At an axial stress of the flange 17.1 of the stop ring 17 by the piston 5, this acts as a spring element by the wall portion 17.3 bent in the direction of the piston 5 and thus springs back, whereby a plastic deformation is counteracted.

LIST OF REFERENCE NUMBERS

1 coupling actuation system

2 actuating device

3 donor side

4 master cylinders

5 pistons

5.1 paragraph

5.2 face

6 hydraulic fluid

7 hydraulic line

8 taker side

9 slave cylinders

10 clutch

11 geberseitiger piston

12 housing

13 Outer cylinder wall

14 Inner cylinder wall

14.1 end face of the inner cylinder wall

14.2 fret

15 pressure chamber

16 release bearing

17 stop ring

17.1 flange

17.2 bead

17.3 wall area

17.4 stop area 17.5 form elements

17.6 fret

18 area

L longitudinal axis

H height of the wall area

T depth of the form elements

Claims

claims

Piston-cylinder unit, in particular slave cylinder (9) of a disengagement system for a clutch or brake system of a motor vehicle, having a housing (12) arranged concentrically about a transmission input shaft and having a radially outer cylinder wall (13) and a radially inner cylinder wall (14) between which a pressure chamber (15) is formed and an acted upon by a pressure medium and with a release bearing (16) in operative connection annular piston (5) is arranged axially movable, wherein the stroke of the piston (5) in the direction of the release bearing (16 ) is bounded by a stop region (17.4) which is formed on a stop ring (17) arranged on the inner cylinder wall (14), characterized in that the stop ring (17) has a radially outwardly pointing flange (17.1) Direction of the end face (14.1) of the inner cylinder wall (14) facing mold elements (17.5).

Piston-cylinder unit according to claim 1, characterized in that the shaped elements (17.5) of the flange (17.1) of the stop ring (17) on the end face (14.1) of the inner cylinder wall (14) abut.

Piston-cylinder unit according to claim 1 or 2, characterized in that the mold elements (17.5) are ausgebldet as bulges of the stop ring (17).

Piston-cylinder unit according to one of claims 1 to 3, characterized in that the stop ring (17) has a peripheral in the direction of the piston (5) curved wall portion (17.3), on which the stopper area (17.4) is formed.

Piston-cylinder unit according to one of claims 1 to 4, characterized in that the stop ring (17) has a substantially parallel to the travel of the piston (5) lying wall portion (17.3), on the end face of the stop region (17.4) is formed ,

Piston-cylinder unit according to one of claims 1 to 5, characterized in that the stop area (17.4) of the stop ring (17) at least partially radially outwardly beyond the end face (14.1) of the inner cylinder wall (14) protrudes.

7. Piston-cylinder unit according to one of claims 1 to 6, characterized in that the stop ring (17) has a radially inwardly of the flange (17.1) adjoining collar (17.6) and with the collar (17.6) in the inner diameter the inner cylinder wall (14) is received.

8. piston-cylinder unit according to one of claims 1 to 7, characterized in that on the collar (17.6) of the stop ring (17) to the inner diameter of the inner cylinder wall (14) reaching bead (17.2) in the manner of a torus is hided, which is supported on the inner diameter of the inner cylinder wall (14)

9. Piston-cylinder unit according to one of claims 1 to 8, characterized in that the inner cylinder wall (14) end has a radially inwardly facing collar (14.2), via which the stop ring (17) with its bead (17.2) in operative relationship is such that the stop ring (17) is axially secured in position.

10. piston-cylinder unit according to one of claims 1 to 9, characterized in that the height (H) of the wall portion (17.3) of the stop ring (17) substantially the depth (T) of the in the flange (17.1) formed form elements (17.5) corresponds.