GB2132722A

GB2132722A - Master cylinder, and reservoir assembly

Info

Publication number: GB2132722A
Application number: GB08333346A
Authority: GB
Inventors: John Flory Pickering
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1982-12-14
Filing date: 1983-12-14
Publication date: 1984-07-11
Also published as: JPS59130776A; ES527992A0; GB2132722B; DE8335919U1; IT8324135A1; IT1168736B; IT8324135A0; ES8500590A1; GB8333346D0; FR2537521A1

Abstract

A master cylinder for an hydraulic pressure system has a pressure cylinder (1) on which is mounted a reservoir (11), the interiors of the cylinder and reservoir being in communication by way of a port (13), a passage (14) and a connector (18). The connector is provided with a seat (20) for engagement by a pressure test probe (P) in such a manner e.g. by means of conical or part-spherical engagement surfaces as to permit degree of variation in the angle of application of the probe to the device whilst permitting a substantially fluid-tight seal between the two to be obtained. <IMAGE>

Description

SPECIFICATION Master cylinder This invention relates to a master cylinder for an hydraulic pressure system, primarily for a vehicle braking system, and more particularly to a master cylinder which includes a pressure cylinder and an initially separate reservoir mounted thereon, the interiors of the pressure cylinder and reservoir being in communication by way of a transverse port through the peripheral cylinder wall.

For safety reasons, it is common practice to test the integrity of newly assembled master cylinders by applying high pressure to the interior of the cylinder and checking for unacceptable leaks which may be caused, for example, by damaged or incorrectly assembled components such as pistons or seals.

High pressure hydraulic fluid for such testing is usually applied through an elongate hollow probe which can be inserted into the reservoir and placed in communication with an internal port thereof which communicates, in turn, with the interior of the cylinder. The correct positioning of such a probe in order to establish a substantially fluid-tight connection can sometimes be difficult especially when the transverse cylinder port is spaced from the reservoir longitudinally of the cylinder and a communicating passage has to be provided between that port and the interior of the reservoir, which passage may lead into the reservoir laterally of the latter, as for example in some of the arrangements described in our co-pending published Application No.

2082277. Because of constraints imposed by internal components of the reservoir, manipulation of the probe to a satisfactory angled position for the purpose of making the connection can be severely hindered.

An object of the invention is to provide a master cylinder in which the application of a high pressure testing probe to an internal reservoir port is facilitated.

According to the invention, a master cylinder for an hydraulic pressure system comprises a pressure cylinder and an initially separate reservoir mounted thereon, the interiors of the pressure cylinder and reservoir being in communication by way of a connector which provides a passage between the reservoir interior and a transverse port through the peripheral cylinder wall, the connector being capable of receiving a test probe in such a manner as to permit a degree of variation in the angle of application of the probe to the device whilst permitting a substantially fluid-tight seal between the two to be obtained.

The connector may provide a seat, typically of conical or part-spherical form, engageable by the end of the probe which would preferably be correspondingly shaped. The connector may conveniently provide a socket for reception of the probe, the seat then preferably being within the socket.

In one convenient practical arrangement, first and second portions of the connector are arranged in mutual angled typically generally perpendicular, relationship, one portion extending within the reservoir and carrying the seat, the other portion extending generally longitudinally of the cylinder for connection to a passage extending axially of the cylinder and communicating with said transverse cylinder port.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a longitudinal cross-section of the form of the master cylinder of the invention: Figure 2 is a split cross-section respectively on the lines A-A and B-B of Fig. 1; Figures 3 and 4 are respectively crosssections along the lines Y and X of Fig. 2, and Figure 5 is a detail in plan view of a component of the master cylinder of Figs. 1 to 4; The drawings illustrate a tandem master cylinder for use in a dual circuit braking system and comprising a pressure cylinder 1 having an axial blind bore 2, the open end of which is closed by a closure member in the form of a sleeve 3.The bore 2 is divided by a piston 4 into pressure chambers 5 and 6, the piston being connected by a device 7 of variable length to another piston 8 to which is secured on actuating rod 9 extending axially outwardly of the cylinder. A spring 10 acts to axially separate the pistons 4 and 8 to an extend limited by the telescopic device 7. A reservoir 11 is mounted at the upper side of the cylinder 1 and communicates respectively with the chambers 5 and 6 through ports 1 2 and 1 3 formed transversely through the cylinder wall. Communication between the reservoir and port 1 3 takes place by way of an axial passage 14 formed in the closure member 3.The passage 1 4 is formed partly in an axial extension 1 6 of the closure and leads at one end into a recess 1 5 registering with the port 1 3. In accordance with the invention a connector 1 8 is provided, being received and sealed within an opening in the base of the reservoir 11. The free end of the extension 1 6 of the closure member 3 is inserted into a bore portion 1 7 of the connector. A seal 1 6A surrounds the extension 1 6 within the connector device 1 8 and is retained in position by a resilient clip 21, as of spring steel for example.As will be seen from Fig. 5, the clip is generally U-shaped in plan and embraces a boss portion 22 of the connector 1 8 with arms 21A, 21 B thereof resiliently snap-engaged behind the boss portion. The extension 1 6 of the closure member 3 extends through the clip 21 for reception within the connector 18 as described.

The bore portion 1 7 communicates via a passage 1 8A with an enlarged opening 1 9 of the connector located within the reservoir, the junction between the passage 1 8A and opening 1 9 being in the form of a conical seat 20 designed to permit the application of a high pressure test probe (indicated in broken lines at P) to the chamber 6 of the newly assembled master cylinder for the purpose of testing the integrity of the usual piston and seal components thereof. The conical seating permits the test probe a relatively wide angle of approach for connection with the connector 1 8 in order to facilitate its use.

Normal operation of the master cylinder described above will be readily apparent to one skilled in the art and will not be further described.

Before the master cylinder is approved for use in a vehicle braking system, the aforesaid pressure testing of the pressure chamber 6 is carried out using the probe P. It will be seen that the test pressure acts on the inner end of the piston 8 and the resultant force on the piston is reacted on a circlip 8A lodged in a groove in the cylinder wall. The test pressure also acts over a relatively large area of the closure member 3, defined by the annulus presented by a seal 23 surrounding the actuating rod 9 and it is important that the considerable force generated by this pressure is not applied to flimsy structure, such as a housing 24 of an associated servo, since this may result in damage to that structure.

This force is reacted on the cylinder 1 and, in the present embodiment, this is achieved by the use of a coupling device in the form of a generally U-shaped spring steel clip 26 (Fig.

2) the arms 27 of which extend through transverse openings 28 formed in the end closure 3 and engage in an annular groove 29 formed in the outer peripheral surface of the cylinder 1. Inner end portions 27A of the arms 27 are of greater width than the remainder of the arms so that the arms are able to engage in the groove 29 over a substantial part of the arcuate extent of the latter. This effectively keys the closure member 3 to the cylinder so that any axial force applied to the closure member 3, such as that resulting from the aforementioned high pressure testing, is reacted directly on the cylinder and not, for example, on the booster casing 24. The coupling device 26, on the booste casing 24. The coupling device 26, in this embodiment, lies within the booster casing 24 and is retained in place thereby. It can therefore be fairly readily removed in order to permit the closure member 3 to be dismantled to provide access to the interior of the cylinder when required.

Claims

1. A master cylinder for an hydraulic pressure system comprises a pressure cylinder and an initially separate reservoir mounted thereon, the interiors of the pressure cylinder and reservoir being in communication by way of a connector which provides a passage between the reservoir interior and a transverse port through the peripheral cylinder wall, the connector being capable of receiving a test probe in such a manner as to permit a degree of variation in the angle of application of the probe to the device whilst permitting a substantially fluid-tight seal between the two to be obtained.

2. A master cylinder according to Claim 1 wherein the connector provides a seat engagable by the end of the probe.

3. A master cylinder according to Claim 1 or Claim 2 wherein the seat is of conical or part-spherical form.

4. A master cylinder according to Claim 2 or Claim 3 wherein the connector provides a socket for reception of the probe and the seat is within the socket.

5. A master cylinder according to Claim 1, wherein first and second portions of the connector are arranged in mutually angled relationship, one portion extending within the reservoir and providing a seat engagable by the end of the probe, the other portion extending generally longitudinally of the cylinder for connection to a passage extending axially of the cylinder and communicating with said transverse cylinder port which is spaced from the reservoir longitudinally of the cylinder.

6. A master cylinder according to Claim 5 wherein said first and second portions are in mutually perpendicular relationship.

7. A master cylinder according to any one of the preceding claims wherein the connector is a separate component received and sealed within an opening in the reservoir.

8. A master cylinder according to any one of Claims 5 to 7 wherein said other portion of the connector is connected to an axial extension of an end closure cap of the cylinder, said extension being hollow and constituting said axially extending passage.

9. A master cylinder according to Claim 8 wherein a seal surrounds said axial extension within the connector, the seal being retained in position by a resilient clip through which said extension passes and which snap-engages around a boss formed on the connector.

10. A master cylinder for an hydraulic pressure system substantially as hereinbefore described with reference to the accompanying drawings.