JPH0143336Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to improvements in pressure limiting devices used in dual brake circuits for automobiles.

Known pressure limiting devices for dual brake circuits are disposed between two brake pressure sources and first and second brake motors. Pressure limiting device is 2
The brake motor includes a body having first and second inlet orifices connected to a pressure source and first and second outlet orifices connected to a brake motor. The first fluid passage communicates with the first inlet orifice and the first outlet orifice, and the second fluid passage communicates with the second inlet orifice and the second outlet orifice. In each passage, fluid flow is controlled by a valve having a valve member cooperating with a valve seat. The two valves are disposed coaxially within the body, with the valve disposed in the first passageway cooperating directly with the valve disposed in the second passageway spaced from its valve seat by a force transmission mechanism. , the valve member of the valve is moved away from its valve seat against the action of a spring.

A pressure limiting device of this type, described for example in French Patent No. 1,566,691, is adapted to transmit fluid pressure to each brake motor only up to a predetermined value, commonly referred to as the "shutoff pressure".

The body of a conventionally constructed pressure limiting device consists of two closely coupled body portions with first and second passageways defined therein. As a result, the distance between the valve seats in the first and second passages will be a desired constant value after the two body parts are secured together. However, because the valve in the second body part has a free end that extends to abut the valve in the first body part, the distance between the valve seats due to tolerances between the parts of the pressure limiting device. It may occur that the distances between the valve members of the two valves and the valve members of the two valves do not match and that a small gap exists between the valves in the closed position of the two valves. As a result, the two valves that shut off the fluid flow in the first and second passages are not closed synchronously, resulting in a difference between the shutoff pressures in each passage.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pressure limiting device having a structure that can be adjusted so that the gap between the valves becomes zero when the valve is closed.

Therefore, the present invention provides a main body having a first stepped hole therein and having first and second inlet and outlet orifices, the first inlet orifice, the first outlet orifice, and the first stepped hole. a first passage communicating between the second inlet orifice, the second outlet orifice, and the first stepped hole; 1st
a cylindrical element having a second stepped hole therein which separates the passage from the second passage and forms a part of the second passage; a cylindrical element fitted into the first stepped hole and at one end; a stem receiving a control force transmitted from an external force transmission mechanism; and a first valve seat fixed to the other end of the stem and cooperating with a first valve seat formed in a shoulder of the first stepped hole. a first valve having a valve member for controlling communication through one passageway, the first valve being moved in response to the control force and the pressure delivered to the first inlet orifice; said second valve extending and cooperating directly with said first valve;
a stem coaxially fitted into the stepped hole; and a second valve fixed to the other end of the stem and formed at the shoulder of the second stepped hole substantially parallel to the first valve seat. a second valve having a valve member that cooperates with the seat to control communication through the second passage; and a first elastic device that elastically presses the valve member of the second valve toward the second valve seat. and wherein the axial position of the cylindrical element within the first stepped hole is between the first valve seat and the second valve seat.
A pressure limiting device for a dual brake circuit is provided that is adjustable to vary the axial distance between the valve seat and the valve seat.

According to the above configuration, by adjusting the axial position of the cylindrical element within the stepped hole of the main body, the distance between the two valve seats can be changed so that the distance between the two valves in the closed position becomes zero. This allows the valves to close synchronously and maintain the same shutoff pressure.

Embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, a first embodiment of a pressure limiting device for a dual brake circuit according to the invention is shown, the pressure limiting device being in the position it occupies when the two valves are open.

The pressure limiting device, generally designated 10, includes a body 12 defining a stepped bore 14 separated by a shoulder 20 into a large diameter section 16 and a small diameter section 18.
includes.

A cylindrical element 22 that moves axially within the bore 14 is fitted within the large diameter section 16 . The cylindrical element 22 is a sleeve in this example and is threaded into the bore 14 for axial adjustment. A first inlet orifice 24 in the body 12 opens into a chamber 26 within the bore 14, which chamber is defined between the shoulder 20 and the opposite end surface of the cylindrical element 22. Chamber 26 communicates with a first exit orifice 28 of body 12 via small diameter section 18 and radial passageway 30 . Valve member 34
A first valve 32 comprising a stem 36 and a stem 36 is connected to the chamber 2 of the bore 14.
6 such that the valve member 34 is disposed within the shoulder 20
The inlet orifice 24 cooperates with a valve seat formed in the
and outlet orifice 28 . A stem 36, which is slidably disposed in a sealing manner within the reduced diameter section 18, projects from the reduced diameter section and is urged by a force transmission mechanism, generally designated 38, which includes a pressure limiting device. It provides a control force to the valve 32 that varies depending on the load on the axle of the vehicle to which it is attached. The illustrated force transmission mechanism is of well-known construction and will not be described in detail. Of course, force transmission mechanism 38 is shown by way of example only, and other similar structures may be substituted without departing from the invention. The invention is also applicable to pressure limiting devices in which the control force is determined by a spring with a constant set point irrespective of the load on the axle.

Body 12 has a second inlet orifice 40 and a second outlet orifice 42. The cylindrical element 22 has a stepped bore 44 that includes a shoulder 46 dividing it into a large diameter portion and a small diameter portion. A second valve 48 of the same construction as the first valve 32 is disposed coaxially with the first valve and has a shoulder 46
It cooperates with the valve seat formed in the valve seat. The stem of the valve 48 is disposed in a sealing manner within the small diameter of the bore 44 and is connected to the chamber 26.
The valve member 34 of the first valve protrudes inward and contacts the valve member 34 of the first valve. The large diameter portion of the bore 44 is in constant communication with the inlet orifice 40 via a radial passage 50 within the cylindrical element 22;
The small diameter section is in constant communication with the exit orifice 42 via a groove 52 in the body 12 and a radial passage 54 in the cylindrical element. The large diameter part of the bore 44 is closed in a sealing manner by a plug 56 held by a ring 58. A return spring 60 is supported by the plug 56 and urges the valve member 49 of the valve 48 toward its seat.

The pressure limiting device described above is assembled and adjusted as follows.

a first valve 32 is disposed within the bore 14 of the body 12;
The valve stem 36 slides within the small diameter portion 18 of the bore.
The cylindrical element 22 is then guided into the hole 14 and screwed into said hole as far as possible. The second valve 48 is inserted into the bore 44 of the cylindrical element 22, after which the spring 60 and plug 56 are placed in position. At this time, the stem of the valve 48 presses the valve member 34 of the valve 32 directly onto its seat under the action of the spring 60, so that fluid flows between the first inlet orifice 24 and the first outlet orifice 28.
The flow in the passage has stopped. However, due to the length of the stem of valve 48 and the distance between the valve seats, valve member 49 of valve 48 remains spaced apart from its seat. The cylindrical element 22 is then gradually unscrewed and the shoulder 4
6 contacts the valve member 49 of the valve 48, i.e. until fluid ceases to flow in the second passage between the second inlet orifice 40 and the second outlet orifice 42, the cylindrical element 22 is inserted into the bore 14. along the valve, changing the distance between the valve seats. During this operation, fluid flow within the two passages is controlled by forcing air or liquid into each inlet orifice. 2nd above
Once fluid flow in the passageway is interrupted, the pressure limiting device is adjusted so that there is no gap between the two valves in their closed positions. Thereafter, the pressure limiting device can be used as an adjusted device with a very small distance between the two valves in the closed position obtained by slightly unscrewing the cylindrical element 22. The pressure limiting device is fitted with a force transmission mechanism 38 before being fitted to the vehicle.

In a variation of the method of assembling and adjusting the pressure limiting device of FIG. is brought into contact with the shoulder portion 20. Next, the shoulder 46 is attached to the valve member 4 of the valve 48.
9, and then the spring 60 and plug 56 are in place.

The pressure limiting device described above is covered by French patent no.
It operates in substantially the same manner as described in US Pat. No. 1,566,691 and will not be described in detail.

FIG. 2 shows a second embodiment of a pressure limiting device according to the invention, in which elements identical or similar to those in FIG. 1 are designated by the same reference numerals plus 100. The pressure limiting device 110 of FIG. 2 is virtually identical to that of FIG. 1 except for the following features. That is, the first
Cylindrical element 2 screwed into stepped hole 14 in the figure
2 has been replaced by a piston 162 which is pressed against an adjustable plug 164 by a spring 166 supported on the shoulder 120 of the stepped bore 114 of the body 112. The pressure limiting device of FIG. 2 is assembled and adjusted as follows. The first valve 132 is the hole 1
14 , with the stem of the valve sliding within the small diameter portion 118 of the bore 114 . Spring 166 and piston 162 are then positioned within bore 114. 2nd valve 1
48 is inserted into stepped hole 144 of piston 162, and then spring 160 and plug 164 are placed in position. Plug 164 is screwed in as far as possible to drive piston 162 the maximum amount into hole 114 against spring 166. First and second valves 132 and 148 are in closed and open positions, respectively. Then, as in the embodiment of FIG. It is adjusted by moving it relative to the To this end, the plug 164 is unscrewed until the shoulder 146 contacts the valve member 149 of the valve 148, and the pressure limiting device is adjusted such that at the point of shoulder contact the distance between the valves in the closed position is zero. be done.

Similar to the embodiment of FIG. 1, the pressure limiting device of FIG. 2 operates in the same manner as described in French Patent No. 1,566,691.

Two inlet orifices 2 in the body 12 or 112
4 and 40 or 124 and 140 and the two outlet orifices 28 and 42 or 128 and 142 are configured to allow for proper alignment of the orifices as a pair, compared to conventional pressure limiting devices where there is an angular offset between the orifices. has been done.

Furthermore, in both embodiments, the main body 12 or 11
2 is a cylindrical element 2 separating the first and second passages;
2 or a bleed orifice 68 or 168 opening into the bore 14 or 114 between the two annular seals in the groove of the piston 162.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a first embodiment of a pressure limiting device according to the present invention, and FIG. 2 is a longitudinal sectional view of a second embodiment of the pressure limiting device according to the present invention. 10,110...pressure limiting device, 12,112
...Body, 14,44,114,144...Stepped hole, 20,46,120,146...Shoulder, 22
...Cylindrical element, 24, 40, 124, 140...
...Entrance orifice, 26...Room, 28, 42, 1
28,142...Exit orifice, 32,132
...First valve, 34, 49, 134, 149... Valve member, 36... Stem, 38... Force transmission mechanism, 4
8,148...Second valve, 56,164...Plug, 60,160,166...Spring, 162...
piston.

Claims (1)

[Claims for Utility Model Registration] 1. A main body having a first stepped hole therein and having first and second inlet and outlet orifices;
a first passage communicating between the first inlet orifice, the first outlet orifice, and the first stepped hole; a second passage communicating between the second inlet orifice, the second outlet orifice, and the first stepped hole; 1st above
a cylindrical element having a second stepped hole therein movably fitted within the stepped hole to isolate the first passageway and the second passageway and forming a portion of the second passageway; A stem that is fitted into the first stepped hole and receives a control force transmitted from an external force transmission mechanism at one end; and a shoulder portion of the first stepped hole that is fixed to the other end of the stem; a valve member for controlling communication through the first passageway in cooperation with a first valve seat formed in the valve member, the valve member being moved in response to the control force and the pressure delivered to the first inlet orifice; a first valve; a stem coaxially fitted within the second stepped bore such that one end extends through the cylindrical element and cooperates directly with the first valve; a valve member fixed to the end portion and controlling communication through the second passageway in cooperation with a second valve seat formed in a shoulder portion of the second stepped hole substantially parallel to the first valve seat; and a first elastic device for elastically pressing a valve member of the second valve toward the second valve seat, the cylindrical element within the first stepped hole. A pressure limiting device for a dual brake circuit, wherein the axial position of is adjustable to change the axial distance between the first valve seat and the second valve seat. 2. The pressure limiting device according to claim 1, wherein the cylindrical element is a sleeve screwed into the first stepped hole. 3. An axially adjustable plug is connected to the first
closing a stepped hole, the cylindrical element comprising a piston movable within the first stepped hole, the piston being supported on a shoulder of the first stepped hole; 2. The pressure limiting device according to claim 1, wherein the pressure limiting device is pressed by the plug. 4. Any one of claims 1 to 3 of the claims registered as a utility model, characterized in that the force transmission mechanism transmits a control force that changes depending on the load on the axle of the vehicle to the first valve. Pressure limiting device as described in .