GB2239915A

GB2239915A - A master cylinder

Info

Publication number: GB2239915A
Application number: GB9026681A
Authority: GB
Inventors: Wolfgang Walther; Otmar Dirauf; Herbert Witzgall
Original assignee: FAG Kugelfischer Georg Schaefer KGaA; Kugelfischer Georg Schaefer and Co
Current assignee: IHO Holding GmbH and Co KG
Priority date: 1989-12-07
Filing date: 1990-12-07
Publication date: 1991-07-17
Also published as: DE3940498A1; GB9026681D0; ES2029618A6

Abstract

A master cylinder, for a hydraulic brake or clutch system of a motor vehicle, comprises pressure chambers 5, 6 arranged in a length of drawn pipe 1 provided with a closed end, a cap 10 carrying a mounting flange 11 disposed at the open end of the pipe, which cap has at least one connecting channel 12 extending therein, and reservoir connector parts (7) welded to the tube. In one embodiment at least one of the reservoir connector parts is formed integrally with the cap (see fig. 3). <IMAGE>

Description

A Master Cv1inder The present invention relates to a master cylinder for a

hydraulic brake or clutch system of a motor vehicle, comprising one or more pressure chambers, which is or are arranged to be acted upon by a piston or respective pistons, a reservoir for the hydraulic fluid, connecting means and connecting passageways between the reservoir and the pressure chambers, and a mounting flange for fastening the cylinder.

A previously proposed master cylinder is described on pages 9, 10 and 11 of our booklet HB 49 109DA. A disadvantage of this cylinder is that its casing is a cast component which is not only heavy and expensive but also requires complicated machining of the cylinder bore. Even the fabrication of a connecting bore between a single non- pressure chamber and a single terminal of the reservoir is difficult.

Thus, there have been searches for different solutions undertaken, as a result of which a complex cylinder has, for example, been proposed, as in DE-A3,411,907 and EP-A- 0, 306,279.

However, the disadvantages of such a construction are as follows:

the locking mechanism, by means of which the cylinder, a separate mounting flange and its counterpart on the vehicle are fastened to the latter, requires high-precision manufacture, which is expensive; sealing problems are likely to occur; the connection between the cylinder and the reservoir differs from the time-tried solution of latching the latter to the former.

An aim of the present invention is to provide a master cylinder of the kind referred to in the opening paragraph which is lighter than the conventional constructions, does not necessitate complicated machining during manufacture and which obviates the disadvantages of the complex cylinders.

Accordingly the present invention is directed to a master cylinder as set out in the opening paragraph of the present specification in which the pressure chambers are arranged in a length of a drawn pipe provided with a closed end, the pipe length is provided with at least one connector part welded thereon and serving to hold the reservoir by means of a connection, a cap is provided which carries the mounting flange and is arranged at the open end of the length of pipe, and in which at least one connecting passageway extends within the cap.

Advantageously a length of tube forming a connecting passageway is arranged -between the reservoir and the cap.

Preferably the tube length is formed integrally with the reservoir.

In a preferred embodiment at least one connector part for the reservoir is formed integrally with the cap.

The arrangement of a connecting passageway in the cap, which also carries the mounting flange, renders an inexpensive, reliable and simple construction of the master cylinder possible. Moreover, the integration of the connector part or parts reduces the overall number of components, and compared with the conventional castcylinder construction, the weight of the casing may be reduced to one third of that of a previously used casing. An example of a master cylinder made in accordance with the present invention is shown in the accompanying drawings, in which: Figure 1 is an axial sectional view of such a master cylinder; Figure 2 is a part-sectional view of a modification of a part of the master cylinder illustrated in Figure 1; and Figure 3 is an axial section of a further modification of the cylinder illustrated in Figure 1. 20 A length of pipe 1 shown in Figure 1, having an open end and a closed end, contains a primary piston and a secondary piston 3, which are arranged to be axially displaceable in the bore of the pipe 1. The pistons are provided with seals 4 and form pressure chambers 5 and 6 respectively. Connector parts 7 f or a reservoir 8 are welded onto the pipe length 1. The reservoir 8 is tightly joined via seals 9 to the connector parts 7 by means of a latch connection between the reservoir 8 and the seals 9. A cap 10 carrying a mounting flange 11 is arranged at the open end of the pipe length 1. A connecting passageway or channel 12 extends in the cap 10 and serves to feed 5 pressure fluid from the reservoir 8 through a tube length 13 into a pressure chamber 5 and, respectively, a nonpressure chamber 14. A pressure chamber 6 and a nonpressure chamber 15 are connected to the reservoir by radially extending bores 16.

The cap also includes a seal 17 and a guide piece 18 for the piston shaft 21 by means of which the master cylinder is operated. The cap 10 is made of, for example, diecast aluminium or of a synthetic material. This, taken in conjunction with the pipe length 1, renders a light cylinder construction possible which, compared with the conventional cast-cylinder construction, is considerably lighter. The tube length 13, in the embodiment illustrated in Figure 1, is a separate component arranged between the reservoir 8 and the cap 10. 20 However, the tube length may alternatively be formed integrally with the reservoir 8, as illustrated in Figure 2. Figure 3 illustrates a version of the master cylinder in which one of the connector parts 7 for the reservoir 8 is formed integrally with the cap 10. otherwise the construction corresponds to that shown in Figure 1, except for the tube length 13 which is omitted.

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Claims

1. A master cylinder for a hydraulic brake" or clutch system of a motor vehicle, comprising one or more pressure chambers, which is or are arranged to be acted upon by a piston or respective pistons, a reservoir for the hydraulic fluid, connecting means and connecting passageways between the reservoir and the pressure chambers, and a mounting flange for fastening the cylinder, in which the pressure chambers are arranged in a length of a drawn pipe provided with a closed end, the pipe length is provided with at least one connector part welded thereon and serving to hold the reservoir by means of a connection, a cap is provided which carries the mounting f lange and is arranged at the open end of the length of pipe, and in which at least one connecting passageway extends within the cap.

2. A master cylinder according to claim 1, in which a length of tube forming a connecting passageway is arranged between the reservoir and the cap.

3. A master cylidner according to claim 2, in which the tube length is formed integrally with the reservoir.

4. A master cylinder according to claim 1, in which at least one connector part for the reservoir is f ormed integrally with the cap.

5. A master cylinder for a hydraulic brake or clutch system of a motor vehicle, substantially as described herein with reference to Figure 1, or with reference to Figure 1 modified in accordance with Figure 2 or Figure 3 of the accompanying drawings.

Published 199 1 at The Patent Office. State House. 66/71 High Holborn, London WC I R 47P. Further copies may be obtained from Sales Branch, Unit 6, Nine Mile Point Cwmfclinfach, Cross Keys, Newport, NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent.