GB2111621A

GB2111621A - Reservoir for master cylinder

Info

Publication number: GB2111621A
Application number: GB08137254A
Authority: GB
Inventors: Colin Mcdonald; Peter Gerald Mayson
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1981-12-10
Filing date: 1981-12-10
Publication date: 1983-07-06

Abstract

A reservoir for a brake master cylinder allows an outlet port (11) to be positioned substantially above the bottom wall (8) of a fluid chamber by providing a passage (14) which communicates the port with a point at a lower level in the chamber. The passage is defined by an insert member (13) fitted between the side wall (6) and an internal partition wall (9) and extending downwardly into a well (12) formed by a depression in the bottom wall (8). <IMAGE>

Description

SPECIFICATION Reservoir for master cylinder This invention relates to a reservoir for a master cylinder such as in a vehicle braking system.

With the continually increasing costs of fossil fuels there is increasing pressure on vehicle manufacturers to make vehicles more compact. As a result there is less space in the engine compartment to accommodate the components with are normally housed there.

In some cases the clearance height above an inlet port of a brake master cylinder and available to receive a reservoir for storing a supply of brake fluid is restricted. So that the reservoir tank is still able to hold the same volume of fluid, it may have an increased area, as seen in horizontal cross-section, to compensate for the reduced height. Nevertheless a reservoir of this form suffers a serious disadvantage in as much that it has been found under certain conditions, e.g. when the brakes are applied heavily while the vehicle is traversing a sharp bend, the fluid may be thrown to one end of the chamber with the result that the fluid level falls below the outlet port and air may enterthe braking system.

The present invention aims at a solution to this drawback, and in accordance with the invention there is provided a reservoir defining a storage chamber for fluid, an outlet port in a wall of the reservoir and positioned at a level above the chamber bottom, and a passage connecting the outlet port to the chamber and opening in the chamber at a level below the outlet port.

With a reservoir of this construction the passage may be arranged to open at a level below which the fluid level cannot fall under normal driving conditions thereby eliminating the risk of air entering the braking system even if the fluid level actually falls below the vertical position of the outlet port.

In a preferred reservoir the chamber has a substantially horizontal bottom wall and a well extending downwardly from the bottom wall, the passage opening in the well. In this way the risk of air passing through the outlet port is even more positively averted.

The passage may be integrally formed with the main walls of the master cylinder but in one preferred embodiment is defined by an insert mounted in the reservoir. In the case of a double chamber reservoir for use with a dual master cylinder, the insert can be conveniently supported onan interior wall dividing the chambers.

Amore complete understanding of the invention will be had from the following detailed description which is given with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a reservoir embodying the invention, shown partly cut away to reveal the relevant details; Figure 2 is a partial vertical section through the reservoir; Figure 3 is a view along the line Ill-Ill in Figure 2; and Figures 4A to 4C are front and side elevations and vertical section of the insert shown on an enlarged scale.

The reservoir illustrated in the drawings is of the dual chamber type for use with a vertically mounted tandem master cylinder. A first chamber 1 of gener allycolumnarform is provided with a lower outlet port 2. The second chamber 3 is generally horizontal and of flatter form and includes front and rear end walls, 4,5 opposed side walls 6,7 and a bottom wall 8. Internal partition walls 9 separate the chambers 1, 3, a slot 10 being provided in one such wall to allow fluid to spill over between the chambers during filling. The chamber 3 has an outlet port 11 positioned in the side wall 6, the height of this port above the first port 2 being determined by the particular master cylinder with which the reservoir is to be used and as shown it may be near the level of the bottom wall 8.Below the port lithe bottom wall is formed with a generally semi-cylindrical depression orwell 12. As so far described the reservoir may be made as a single unitary moulding of synthetic plastics material. The reservoir cover (not shown) may be made as a second moulding and welded in place on the reservoir.

An insert member 13 which may be conveniently moulded from polypropylene or hard rubber is mounted in chamber 3 between the sidewall 6 and the opposed interior partition wall 9. The member 13 is of generally rectangular configuration and includes a passage 14 having a horizontal first portion opening through a hemi-spherical pip-like projection 15 adapted to engage sealingly in the outlet port 11 as seen in Figure 2, and a vertical portion extending downwardly to the lower end of member 13 which is located close to the bottom of the well 12. A securing clip 16 of inverted L-shape is adapted to pass through the lower end of slot 10 and to grip the partition wall 9 to retain the member 13 firmly in position. To permit unrestricted flow of fluid into the passage 14 the member is provided with a transverse groove 17 at its lower end to define a side opening.As shown in Figures 2 to 4 the groove may extend to one side only.

From the foregoing description it will be understood that the passage 14 of member 13 communicates the outlet port 11 with the interior of chamber 3 at a level which is substantially below the level of the port itself. Even if the fluid in chamber 3 is thrown forwards away from the port 11 there is no risk of the bottom opening of passage 14 becoming uncovered, at least under normal driving conditions. The insert member also acts as a baffle to slow down any tendency for fluid to pass from one side to the other of the well cavity, which further assists in minimising any danger of the passage opening becoming uncovered.

1. A reservoir for a master cylinder, comprising a storage chamber for fluid, an outlet port in a side wall of the chamber, the outlet port being positioned at a level above the chamber bottom, and a passage communicating the outlet port with the chamber interior and opening into the chamber at a level substantially below the outlet port.

2. A reservoir according to claim 1, wherein the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Reservoir for master cylinder This invention relates to a reservoir for a master cylinder such as in a vehicle braking system. With the continually increasing costs of fossil fuels there is increasing pressure on vehicle manufacturers to make vehicles more compact. As a result there is less space in the engine compartment to accommodate the components with are normally housed there. In some cases the clearance height above an inlet port of a brake master cylinder and available to receive a reservoir for storing a supply of brake fluid is restricted. So that the reservoir tank is still able to hold the same volume of fluid, it may have an increased area, as seen in horizontal cross-section, to compensate for the reduced height. Nevertheless a reservoir of this form suffers a serious disadvantage in as much that it has been found under certain conditions, e.g. when the brakes are applied heavily while the vehicle is traversing a sharp bend, the fluid may be thrown to one end of the chamber with the result that the fluid level falls below the outlet port and air may enterthe braking system. The present invention aims at a solution to this drawback, and in accordance with the invention there is provided a reservoir defining a storage chamber for fluid, an outlet port in a wall of the reservoir and positioned at a level above the chamber bottom, and a passage connecting the outlet port to the chamber and opening in the chamber at a level below the outlet port. With a reservoir of this construction the passage may be arranged to open at a level below which the fluid level cannot fall under normal driving conditions thereby eliminating the risk of air entering the braking system even if the fluid level actually falls below the vertical position of the outlet port. In a preferred reservoir the chamber has a substantially horizontal bottom wall and a well extending downwardly from the bottom wall, the passage opening in the well. In this way the risk of air passing through the outlet port is even more positively averted. The passage may be integrally formed with the main walls of the master cylinder but in one preferred embodiment is defined by an insert mounted in the reservoir. In the case of a double chamber reservoir for use with a dual master cylinder, the insert can be conveniently supported onan interior wall dividing the chambers. Amore complete understanding of the invention will be had from the following detailed description which is given with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a reservoir embodying the invention, shown partly cut away to reveal the relevant details; Figure 2 is a partial vertical section through the reservoir; Figure 3 is a view along the line Ill-Ill in Figure 2; and Figures 4A to 4C are front and side elevations and vertical section of the insert shown on an enlarged scale. The reservoir illustrated in the drawings is of the dual chamber type for use with a vertically mounted tandem master cylinder. A first chamber 1 of gener allycolumnarform is provided with a lower outlet port 2. The second chamber 3 is generally horizontal and of flatter form and includes front and rear end walls, 4,5 opposed side walls 6,7 and a bottom wall 8. Internal partition walls 9 separate the chambers 1, 3, a slot 10 being provided in one such wall to allow fluid to spill over between the chambers during filling. The chamber 3 has an outlet port 11 positioned in the side wall 6, the height of this port above the first port 2 being determined by the particular master cylinder with which the reservoir is to be used and as shown it may be near the level of the bottom wall 8.Below the port lithe bottom wall is formed with a generally semi-cylindrical depression orwell 12. As so far described the reservoir may be made as a single unitary moulding of synthetic plastics material. The reservoir cover (not shown) may be made as a second moulding and welded in place on the reservoir. An insert member 13 which may be conveniently moulded from polypropylene or hard rubber is mounted in chamber 3 between the sidewall 6 and the opposed interior partition wall 9. The member 13 is of generally rectangular configuration and includes a passage 14 having a horizontal first portion opening through a hemi-spherical pip-like projection 15 adapted to engage sealingly in the outlet port 11 as seen in Figure 2, and a vertical portion extending downwardly to the lower end of member 13 which is located close to the bottom of the well 12. A securing clip 16 of inverted L-shape is adapted to pass through the lower end of slot 10 and to grip the partition wall 9 to retain the member 13 firmly in position. To permit unrestricted flow of fluid into the passage 14 the member is provided with a transverse groove 17 at its lower end to define a side opening.As shown in Figures 2 to 4 the groove may extend to one side only. From the foregoing description it will be understood that the passage 14 of member 13 communicates the outlet port 11 with the interior of chamber 3 at a level which is substantially below the level of the port itself. Even if the fluid in chamber 3 is thrown forwards away from the port 11 there is no risk of the bottom opening of passage 14 becoming uncovered, at least under normal driving conditions. The insert member also acts as a baffle to slow down any tendency for fluid to pass from one side to the other of the well cavity, which further assists in minimising any danger of the passage opening becoming uncovered. CLAIMS

2. A reservoir according to claim 1, wherein the chamber has a substantially horizontal bottom wall, a recess in the bottom wall defines a downwardly extending well, and said passage opens into the well.

3. A reservoir according to claim 2, wherein said well is located adjacent said side wall and beneath said port, said passage extending downwardly from the port to the well adjacent the inside surface of the side wall.

4. A reservoir according to claim 1,2 or 3, wherein the passage is defined by means integrai with said side wall.

5. A reservoir according to claim 1,2 or 3, wherein the passage is defined by an insert member mounted in the reservoir chamber.

6. A reservoir according to claim 5, wherein an inner wall is spaced from said side wall and the insert member is received between said walls with a close fit whereby the insert member is pressed into sealing engagement with the outlet port.

7. A reservoir according to claim 6, wherein the insert member comprises clip means for securing the insert member in predetermined position on the inner walL

8. A reservoir according to any one of the preceding claims, wherein a duct is connected to the lower end of the passage and extends transversely therefrom to define a lateral inlet to the passage.

9. A reservoir according to claim 8, wherein said duct is defined by a downwardly open groove.

10. A reservoir substantially as herein described with reference to the accompanying drawings.