GB2098697A

GB2098697A - Apparatus for hydraulically actuating a friction clutch for motor vehicles

Info

Publication number: GB2098697A
Application number: GB8213913A
Authority: GB
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 1981-05-15
Filing date: 1982-05-13
Publication date: 1982-11-24
Also published as: GB2098697B; FR2505955B1; FR2505955A1; IT1152159B; DE3119367C1; IT8221255A0

Abstract

Apparatus for hydraulically actuating a friction clutch for motor vehicles, comprising an hydraulic cylinder (9) having a tubular operating piston (8) and a release bearing (6), the non- rotating ring of which is lengthened to form a cylindrical extension (7). The operating piston (8) and the cylindrical extension (7) can be locked together by means of a shackle or claw (12). The friction clutch can therefore be easily assembled and dismantled. The shackle (12) may be of wire as shown or may instead be a claw or claws mounted pivotally on the piston (8) to engage an annular flange on the extension (7). <IMAGE>

Description

SPECIFICATION Apparatus for hydraulically actuating a friction clutch for motor vehicles This invention relates to apparatus for hydraulically actuating a drawn friction clutch for motor vehicles.

German Patent No. 694,864 shows and describes a friction clutch wherein the tubular operating piston of an hydraulic clutch-actuating cylinder is screwed on to the non-rotating bearing ring of a release bearing. Because of this construction, the assembly of the friction clutch during series production and its later dismantling in service work-shops is rendered difficult so that it cannot be used in practice. This applies particularly when the housing surrounding the friction clutch is integral with the gearbox.

German Published Specification No. 29 15 989 describes locking means for a drawn friction clutch, a non-rotating bearing ring of the release bearing being lengthened so that it also forms the operating piston of an hydraulic clutch-operating cylinder.

Locking takes place either between the housing surrounding the friction clutch and the hydraulic cylinder, or on the rotating ring of the release bearing. In this case, an additional part is provided between the bearing ring and a plate spring. The disadvantage of such a locking system resides in the fact that the hydraulic cylinder and the release bearing are combined to form a single component, which is not desirable in many cases. On the other hand, when locking is carried out on the rotating bearing ring, additional measures are necessary for relieving the locking means of centrifugal force.

The aim of the present invention is to develop an hydraulically-actuated friction clutch for motor vehicles that can be readily assembled and dismantled, and wherein the release bearing and hydraulic cylinder are formed as two separate constructional groups.

With this aim in view, the invention is directed to apparatus for hydraulically actuating a friction clutch for motor vehicles, comprising an hydraulic cylinder having a tubular operating piston arranged in spaced relationship around a shaft driven by the friction clutch, the cylinder being secured to a housing surrounding the friction clutch, and a release bearing having a non-rotating bearing ring which co-operates with the operating piston, in which the operating piston and a cylindrical extension of the non-rotating bearing ring engage one within the other and can be locked together.

The advantages of the invention include the fact that, because the operating piston is combined with a non-rotating bearing ring, additional steps for relieving the locking means of centrifugal force are not required. Furthermore, the release bearing and the hydraulic cylinder can be released separately during repair of the clutch, and in many cases this has the favourable result of reducing the cost of repairs.

Two forms of apparatus in accordance with the invention are shown in the accompanying drawings, in which Figure 1 is a section through one form of friction clutch in accordance with the invention; Figure 2 is a section taken on the line ll-ll in Figure 1; and Figure 3 is a section through a second form of construction in accordance with the invention.

Figure 1 shows a drawn friction clutch comprising a friction disc 1 which is pressed by a plate spring 2 through the intermediary of a pressure plate 3 against a flywheel 4 of an internal combustion engine the other parts of which are not illustrated.

The friction disc 1 is mounted to be axially displaceable on a shaft 5 but not to rotate relatively thereto. A release bearing 6 is arranged on the plate spring 2 in such a manner that it concentrically surrounds and is spaced from the shaft 5. The non-rotating ring of the release bearing 6 is lengthened to form a cylindrical extension 7. This extension 7 projects into a tubular operating piston 8 which likewise surrounds and is spaced from the shaft 5 and which moves in an hydraulic cylinder 9. The hydraulic cylinder 9 itself is screwed, by way of an external flange 10 on the cylinder, to a housing 11 which surrounds the friction clutch and is formed integrally with a gearbox, details of which are not shown.

The operating piston 8 can be locked to the cylindrical extension 7 of the release bearing 6 by means of a shackle or claw 12. For this purpose the operating piston has, in its periphery, two parallel channels 13 which are disposed at right angles to the longitudinal axis and extend through the inner cylindrical surface of the piston. Furthermore, an annular channel 14 is formed in the cylindrical extension 7 of the non-rotating bearing ring, the core diameter of this channel corresponding approximately to the distance between the channels 13 formed in the operating piston 8. The shackle 12 is illustrated in greater detail in Figure 2. It is made of steel wire and comprises a grip portion 15 which is extended in the form of two substantially parallel limbs. Along their further length, the limbs first comprise outwardly-bowed zones 16 forming a release portion.The limbs then have a locking portion 17 and, finally, they terminate in ends which are bent outwardly to form hooks. In addition, the shackle 12 comprises, between the grip part 15 and the release portion 16, an angled part 22 which, as will be described later, serves as a stop during dismantling of the clutch. As will be seen, the limbs of the shackle are guided in the channels 13 formed in the operating piston 8.

For the purpose of assembling the clutch, its release bearing is previously mounted on the crank housing, and the hydraulic cylinder 9 together with its operating piston 8 is firmly secured on the housing 11 by means of screws. The shackle 12 is fitted in the channels 13 formed in the operating cylinder 8 in such a way that it occupies its "release" position.

When the two housings are brought together, the tubular operating piston 8 slides over the cylindrical extension 7 of the release bearing 6 until the channels 13 register with the annular channel 14.

After the housings have been secured, the shackle 12 is drawn, by way of an opening 18 formed in the housing 11, into the position illustrated in Figure 2, so that its locking portion 17 engages in the annular channel 14. A clip 19, which is fitted on to the hook-shaped ends of the shackle 12, prevents the limbs from splaying. The opening 18 in the housing 11 is closed off to damp down noise by means of a suitably shaped cap 20.

Operation of the clutch shown in Figure 1 is initiated by actuating a clutch pedal (not illustrated) to cause pressurised fluid to flow into the operating chamber 21 by way of a port associated with the hydraulic cylinder 9. The operating piston 8 is pressed rearwardly in the direction indicated by the arrow and releases the friction clutch by way of the shackle 12 and the release bearing 6.

During assembly of the clutch, the shackle 12 is pushed into its release position (in the direction of the arrow shown in Figure 2), this position being determined by the angled zone 22, which acts as a stop. The hydraulic cylinder can then be retracted from the release bearing so that further dismantling of the clutch becomes possible.

In the second form of clutch-actuating apparatus illustrated in Figure 3, the cylindrical extension 7' of the release bearing 6 has an annular flange 23. The operating piston 8' of the hydraulic cylinder 9 carries a claw 24 (as in Figure 3) or several such claws 24 which engage the rear of the annular flange 23 in the locking position. The or each claw 24 is swivellably mounted in a carrier 25 secured on the periphery of the operating piston 8'. A setting ring 26 surrounds the claw or claws 24 and is displaceable on a slide face 27 of the claw carrier 25, which face extends in the same axial direction as does the operating piston 8'. Upon displacement, the setting ring opens and closes the claw or claws 24 by swivelling it or them into position by way of a corresponding bevelled portion at the upper edge of the or each claw 24, the claw or claws being held in that position. A stop on the claw 24 or on each of them and on the slide face 27 limits the displacement distance of the setting ring. The setting ring 26 can be held in each of its positions by a screw, not illustrated in the drawing.

Claims

1. Apparatus for hydraulically actuating a friction clutch for motor vehicles, comprising an hydraulic cylinder having a tubular operating piston arranged in spaced relationship around a shaft driven by the friction clutch, the cylinder being secured to a housing surrounding the friction clutch, and a release bearing having a non-rotating bearing ring which co-operates with the operating piston, in which the operating piston and a cylindrical extension of the non-rotating bearing ring engage one within the other and can be locked together.

2. Apparatus according to claim 1, in which the cylindrical extension extends at least partially within the operating piston.

3. Apparatus according to claim 2, in which (a) the operating piston has, at its periphery, two parallel channels which lie at right angles to the longitudinal axis and extend through the wall of the piston; (b) an annular channel is formed in the cylindrical extension of the non-rotating bearing ring, the core diameter of which channel corresponds approximately to the distance between the channels formed in the operating piston; and (c) the operating piston is locked to the bearing ring by a shackle which is fixed in the channels in the operating piston and engages in the annular channel formed in the bearing ring.

4. Apparatus according to claim 3, in which the shackle is made of steel wire and forms a grip part which is extended as two substantially parallel limbs, and in which the limbs are first formed as a release portion by means of outwardly bowed zones, then transposed into a locking portion, and, finally, terminate in ends which are bent outwards to form hooks.

5. Apparatus according to claim 4, in which, between its grip part and its release portion, the shackle has an angled part serving as a stop for dismantling the clutch, and in which the limbs of the shackle are held together by a clip at their hooked ends.

6. Apparatus according to any preceding claim, in which an annular flange is provided on the cylindrical extension of the bearing ring, and one or more claws is or are provided on the operating piston, the claw or claws being adapted to engage the annular flange when the operating piston is locked to the bearing ring.

7. Apparatus according to claim 6, in which a setting ring surrounds the claw or claws and holds them in their locking position, and in which the claws are bevelled at their upper edges so that the claws open and close when the setting ring is axially displaced.

8. Apparatus according to claim 7, in which the setting ring can be set and held by a screw.

9. Apparatus for hydraulically actuating a friction clutch for motor vehicles substantially as described herein with reference to Figures 1 and 2 or Figure 3 of the accompanying drawings.