GB2085988A

GB2085988A - Pressure control valve

Info

Publication number: GB2085988A
Application number: GB8127795A
Authority: GB
Original assignee: Alfred Teves GmbH
Current assignee: Continental Teves AG and Co oHG
Priority date: 1980-10-16
Filing date: 1981-09-15
Publication date: 1982-05-06
Also published as: DE3039060C2; FR2493247B2; GB2085988B; DE3039060A1; FR2493247A2

Abstract

In a twin-design dual-circuit pressure control valve for a hydraulic vehicle brake system, a control force applying lever (4) pivotally mounted on a spindle (2) acts via indentations (5) on respective proportioning valve control pistons (6). The lever is articulated for rocking movement by virtue of the fact that the spindle (2) passes through an oversize bore (7) in a housing (1) and is held within the bore by means of a rubber sleeve (3). Tilting of the spindle (2) is limited by engagement with the annular edges (8) of the bore (7). The spindle (2) may pivot in a metal sleeve (10) within the resilient sleeve (3) which may have a cylindrical or convex exterior. <IMAGE>

Description

SPECIFICATION Pressure control valve This invention relates to a twin-design dualcircuit pressure control valve of the kind having a change-over point which is adjustable from the outside, the pressure control valve serving for dual-circuit hydraulic brake systems of automotive vehicles and having two cylinders which are connected each in one of the brake circuits, which are arranged in parallel to each other and which house the control pistons whose actuating tappets project outwardly on the same front face of the cylinder and are acted upon directly by a common control lever, the control lever being adapted to be acted upon by a control force and being tiltably supported at the housing around a transverse axis which extends vertically relative to the cylinder axes and around its longitudinal axis, with means being provided for an even distribution of the control force onto the two control pistons and with stop means being provided between the lever and parts which are formed fast with the housing, this stop means limiting the tilting movement of the lever around its longitudinal axis without inhibiting its tilting movement around its transverse axis.

German patent application P 29 27 423.5 describes a dual-circuit pressure control valve which safeguards an even distribution of the control force onto both control pistons without the need for complicated force-transmitting elements in a simple, yet reliable manner. In a preferred embodiment of this known dual-circuit pressure control valve, stop means are provided between the lever and parts which are formed fast with the housing, which stop means limit the tilting movement of the lever around its longitudinal axis without inhibiting its tilting movement around its transverse axis. It is thus achieved that, upon failure of a brake circuit and the retreat of the associated control piston resulting therefrom, the control lever is permitted to follow this movement only by an altogether small amount so that the lever does not exert any force on this control piston.Thus, the remaining, still intact, control piston is now acted upon by the double amount of control force with the load on the control lever not having changed, as a result of which the changeover point of this brake circuit is increased correspondingly.

To arrange for the control lever to be supported tiltably around its longitudinal axis as well, it is provided in an embodiment that the lever includes an articulated axle at its end area remote from the actuating arm, this articulated axle extending in parallel to the lever's transverse axis and being supported in a double conical bore of the housing which expands towards its ends. Moreover, it is proposed that the lever includes at its end area remote from the actuating arm a double conical articulated axle which tapers towards its ends and which is supported in a housing bore whose diameter is substantially constant.

Although the control valve described is characterised by a straightforward design and by ease of assembly and eliminates tolerance and adjusting problems of former devices, manufacture of the double conical bore or of the double conical articulated axle is possible only by resorting to a relatively costly machining operation.

Therefore, it is an object of the present invention to improve upon a dual-circuit pressure control valve of the kind initially referred to in such a manner that a design is achieved in the area of the lever support which is simpler and more favourable with respect to costs.

According to the invention in its broadest aspect, a twin-design dual-circuit pressure control valve of the kind referred to is characterised in that the point of support of the control lever includes a bore, wherein an articulated axle of smaller diameter which is formed at the control lever, is supported in a rubber element.

The practical implementation of this embodiment is a support of the control lever, wherein the bore and the articulated axle are of cylindrical shape and may be manufactured at low cost by employing very simple manufacturing operations. The limitation of the tilting movement of the control lever is predetermined in a straightforward manner by the diameter ratio of bore relative to articulated axle. The rubber element is an inexpensive component which does not have to meet particular requirements with regard to tolerances.

In a preferred embodiment of the arrangement in accordance with the present invention, the rubber element is connected with the articulated axle in the intermediate area of the bore. The restoring forces which the rubber element exerts on the articulated axle will be thus reduced.

Moreover, different kinds of rubber material may be utilized by designing the area longer or shorter corresponding to the elasticity of the rubber material.

If the rubber element is of hollow-cylindrical shape, it represents a component with a simple, geometrical form which permits low-cost manufacture.

In another embodiment of the present invention, the bore includes projections between which the rubber element is axially supported. This ensures a well-defined positioning of the rubber element and, at the same time, a locking mechanism against possible displacements of the rubber element is formed.

In order to reduce the friction forces between the articulated axle and the rubber element, in another embodiment the rubber element is seated with preload on a sleeve whose inside diameter corresponds to the diameter of the articulated axle. Simultaneously, the outer circumferential surface of the rubber element may be enclosed by a sleeve. If the sleeve disposed on the outside is pressed into the bore, a well-defined seating position of the rubber element is the result.

In a particularly straightforward embodiment of the present invention, the bore is radially enlarged in its intermediate area and receives a rubber element. Moreover, this embodiment of the invention may be advantageously designed such that the bore includes a step and that a hollow cylinder is inserted in the bore position having the larger diameter, a rubber element being supported at the inside bore of said hollow cylinder. If the diameter of the hollow cylinder's bore is at the ends smaller than in the intermediate section, the rubber element is prevented from axial displacement relative to the hollow cylinder in a simple manner.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a side view of a dual-circuit pressure control valve according to patent application No.

P. 29 27 423.5, Figure 2 is a partial section taken along line I-I in Figure 1, but showing an embodiment of the present invention, Figure 3 is a sectional view of the support of the control lever in accordance with a second embodiment, and Figure 4 shows a further embodiment.

Like parts have been assigned like reference numerals.

In Figure 1, reference numeral 1 designates a housing, 2 an articulated axle, 3 a rubber element, 4 a control lever and 5 an indentation of the control lever 4. Furthermore, the illustration shows two control levers 6 which are arranged in series in the drawing plane.

Each control piston 6 contains a valve (not shown) which is opened when the control piston 6 is in its advanced position and which connects in this state a (non-illustrated) inlet port with a (nonillustrated) outlet port of a brake circuit, respectively. When a given pressure is exceeded in the outlet circuit, the control piston 6 will be moved to the left in Figure 1. The limitation of the tilting angle around the longitudinal axis of the control level will take place in the event of failure of a pressure circuit, i.e. the associated control piston 6 remains in its inactive end position in this case. By virtue of the limitation of the tilting movement, which is realised in Figure 1 basically by the articulated axle 2 and by rigid stops, the change-over point in the still intact brake circuit will then be approximately doubled.

The sectional view of the point of support illustrated in Figure 2 shows a bore 7 with the articulated axle 2 extending therethrough. The articulated axle 2 has a smaller diameter than the bore 7. The radial space between the articulated axle 2 and the bore 7 is filled by the rubber element 3 in the intermediate portion of the bore 7. The ends of the articulated axle 2 projecting on both sides from the bore 7 are connected to the control lever 4. The support of the articulated axle 2 in the rubber element 3 renders possible, on the one hand, a tilting movement of the control lever around the axis of the articulated axle 2. On the other hand, the articulated axle 2 is able to tilt together with the control lever 4 around its centre of gravity until it abuts at the annular edges 8 of the bore 7.

In the area of the control piston 6, the bore 7 includes radial projections 9 whose distance relative to each other corresponds to the length of the rubber element 3.

The embodiment shown in Figure 3 differs from the embodiment of Figure 2 in that a sleeve 10 is inserted between the inner circumferential surface of the rubber element 3 and the articulated axle 2, which sleeve reduces considerably the friction forces in the case of a tilting movement of the control lever 4 around the axis of the articulated axle 2. It is, furthermore, conceivable to enclose also the outer circumferential surface of the rubber element 3 by means of a second sleeve, preferably a metal sleeve, and to press this outer sleeve into the bore 7.

In the embodiment according to Figure 4, the bore 7 is designed as a stepped bore. Located in the area of the bore 7 of larger diameter is a hollow cylindrical element 11 having its one end surface abutting at the bore step 1 2. The articulated axle 2 is guided with clearance in the inner bore of the hollow cylindrical element 11 having its one end surface abutting at the bore step 12. The articulated axle 2 is guided with clearance in the inner bore of the hollow cylindrical element 11 and a rubber element 3 is received in the radial interspace. The limitation of the tilting movement of the articulated axle 2 is determined in this case by the annular edges 13 which are formed at the ends of the inner bore.

The diameter of the hollow cylinder's bore is at the ends smaller than in the intermediate section, as a result whereof, the hollow cylindrical element 11 is of concave shape in section.

Claims

1. A twin-design dual-circuit pressure control valve of the kind having a change-over point which is adjustable from the outside, the pressure control valve serving for dual-circuit hydraulic brake systems of automotive vehicles and having two cylinders which are connected each in one of the brake circuits, which are arranged in parallel to each other and which house the control pistons whose actuating tappets project outwardly on the same front face of the cylinder and are acted upon directly by a common control lever, the control lever being adapted to be acted upon by a control force and being tiltably supported at the housing around a transverse axis which extends vertically relative to the cylinder axes and around its longitudinal axis, with means being provided for an even distribution of the control force onto the two control pistons and with stop means being provided between the lever and parts which are formed fast with the housing, this stop means limiting the tilting movement of the lever around its longitudinal axis without inhibiting its tilting movement around its transverse axis, characterised in that the point of support of the control lever (4) includes a bore (7) wherein an articulated axle (2) of smaller diameter, which is formed at the control lever (4), is supported in a rubber element (3).

2. A dual-circuit pressure control valve as claimed in Claim 1, characterised in that the rubber element (3) is connected with the articulated axle (2) in the intermediate area of the bore (7).

3. A dual-circuit pressure control valve as claimed in Claim 1 and 2, characterised in that the rubber element (3) is of hollow-cylindrical design.

4. A dual-circuit pressure control valve as claimed in Claim 2 or 3, characterised in that the bore (7) includes radial projections (9) between which the rubber element (3) is axially held.

5. A dual-circuit pressure control valve as claimed in Claim 3, characterised in that the rubber element (3) is seated with preload on a sleeve (10) whose inner diameter corresponds to the diameter of the articulated axle (2).

6. A dual-circuit pressure control valve as claimed in Claim 3, characterised in that the inner and the outer circumferential surface of the rubber element (3) are each enclosed by a sleeve.

7. A dual-circuit pressure control valve as claimed in Claim 6, characterised in that the sleeve disposed on the outside is pressed into the bore (7).

8. A dual-circuit pressure control valve as claimed in Claim 1 and 2, characterised in that the bore (7) is radially enlarged in its intermediate area and receives a rubber element (3).

9. A dual-circuit pressure control valve as claimed in Claim 1 and 2, characterised in that the bore (7) has a step (12) and in that inserted in the bore portion of larger diameter is a hollow cylindrical element 1) whose inner bore accommodates a rubber element (3).

10. A dual-circuit pressure control valve as claimed in Claim 9, characterised in that the diameter of the hollow cylinder's bore is at the ends smaller than in the intermediate section.

1 A dual-circuit pressure control valve substantially as described with reference to Figs. 2 to 4 of the accompanying drawings.