GB1564566A - Pressur*e limiters for a compressed-air braking system - Google Patents

Pressur*e limiters for a compressed-air braking system Download PDF

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Publication number
GB1564566A
GB1564566A GB1878977A GB1878977A GB1564566A GB 1564566 A GB1564566 A GB 1564566A GB 1878977 A GB1878977 A GB 1878977A GB 1878977 A GB1878977 A GB 1878977A GB 1564566 A GB1564566 A GB 1564566A
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GB
United Kingdom
Prior art keywords
pressure
piston
adjusting piston
limiter
valve
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB1878977A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE19762620135 external-priority patent/DE2620135A1/en
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of GB1564566A publication Critical patent/GB1564566A/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/18—Safety devices; Monitoring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/24—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being gaseous
    • B60T13/26—Compressed-air systems

Abstract

In order to take account of the changing pressure requirements such as occur in tractor vehicles, which in solo operation work with a higher pressure, for example of 9.5 bar, and for which only a lower pressure of 7.5 bar (normal pressure) is provided when the trailer is attached, the pressure limiter is inserted into the through-line of the brake system (114, 115). The pressure limiter has a passage with a valve (138, 139), the controlling piston member (137) of which is coupled to a servo piston (141), by means of which the switching point of the pressure limiter (130) can be adjusted. A coupling piece (142) between servo piston (141) and piston member (137) is designed as a plug-in coupling so that a secondary effect caused by the limited pressure also acts on the servo piston (141). A seal (148, 149) of the servo piston (141) is divided into two sections and the gap (151') can be connected by way of a non-return valve (150, 151) to the outside air with a cylindrical piece of hose (152) as closing element. <IMAGE>

Description

(54) IMPROVEMENTS RELATING TO PRESSURE LIMITERS FOR A COMPRESSED-AIR BRAKING SYSTEM (71) We, ROBERT BOSCH GMBH. a German Company, of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a pressure limiter for limiting the available braking pressure in a compressed-air braking system of a motor vehicle and is applicable to a pressure limiter for a braking system described in our earlier patent application No.45134/75 (Serial No.
1,521,525). The invention relates more particularly to a pressure limiter having a valve spring-biassed piston member which is subjected to the pressure to be limited i.e. pressure downstream of the valve, and having a readjusting piston to which a control pressure can be applied to cause the adjusting piston to act on the valve in opposition to the spring bias.
The pressure limiter described in the earlier application has no coupled adjusting piston and the secondary pressure, i.e. the pressure to be limited has hardly any influence on the adjusting piston.
The present invention resides in a pressure limiter for a compressed-air braking system of a motor vehicle which is provided with high-pressure air generating and storing means and a working-pressure braking device which limiter comprises a valve which has a valve seat and a closure member cooperating with the seat and carried by a piston member which is exposed to the pressure to be limited (i.e. the pressure downstream of the seat) and moved thereby to the closed position, and is subjected to the force of an adjustable restoring spring to move the valve to the open position, the piston member being displaceable by means of an adjusting piston, which may be subjected to a control pressure, against the force of the restoring spring in the closing direction of the valve to vary the pressure limited by the valve, the adjusting piston being coupled to the piston member and being sealed with respect to a cylinder bore by two seals received on the adjusting piston and defining therebetween a pressure-relieved intermediate chamber, the pressure to be limited acts on the adjusting piston in a direction opposite to the control pressure.
The pressure limiter according to the invention can be constructed so that it is very easy to assemble because its individual parts used for regulation may all be installed from one side into the pressure limiter housing. A simple socket connection between the piston member and the adjusting piston also makes installation easier.
Separation of the pressure chambers is effected advantageously by means of the pair of seals and a non-return valve which opens towards atmosphere can be provided for venting the chamber between the two seals. By means of the socket connection it is possible to allow the secondary pressure to act on the adjusting piston so that a force which increases the regulator spring force is produced and its availability is advantageous for many purposes.
The invention will be further described, by way of example, with reference to the accompanying drawings in which:- Fig. 1 is a section through a pressure limiter and Fig. 2 is a plan view of a detail of the pressure limiter.
Referring to Fig. 1, a pressure limiter 130 is inserted between lines 114 and 115 by means of an inlet 135 and an outlet 136. The pressure limiter 130 has a piston member 137 having an annular closure member 138 which co-operates with a seat 139 fixed in a housing 140 to form the actual valve 138, 139 of the pressure limiter 130. The piston member 137 is subject to the force of a restoring spring 132 whose initial compres sion is variable by means of a screw 131. In this manner, the change over point of the pressure at which the valve is closed can be varied.
A working cylinder 133 is disposed coaxially with the piston member 137 on the housing 140 of the pressure limiter 130 and forms a caplike closure of the housing 140. An adjusting piston 141 is movable in the working cylinder 133 and has a collar-like end portion 142 at its end facing the piston member 137. A caplike coupling element 145 which is held against a shoulder 143 of the piston member 137 by means of a spring ring 144 is shown in plan view in Fig. 2. It may be seen that it has an oblong hole 146 having an eccentric extension 147. The collar-like end portion of the adjusting piston 141 may be introduced into the eccentric extension 147 and after centering the adjusting piston 141 in the coupling element 145 during assembly, these two parts are securely fastened to one another.
The adjusting piston 141 earriestwoannu- lar seals 148 and 145) which are separated from one another by a pressure-relieved intermediate chamber 15 1'. The cap-like closure 133 of the pressure limiter housing 140 has an annular necked-down portion 150 which is connected by a port 15 1 to the intermediate chamber 151'. A resilient cylindrical hose piece 152 is inserted over the annular necked-down portion 149 and monitors an outside-air connection of the intermediate chamber 151' in the manner of a non-return valve.
A chamber 153 above the adjusting piston 141 serves as a control chamber of the pressure limiter and is connected to a control line 154. A safety valve 155 is provided in the piston member 137. This safety valve 155 may however be omitted.
The pressure limiter operates to a large extent in an identical manner to that described in our earlier patent application No. 45134/75 (Serial No. 1.521 525).
When the mechanically propelled vehicle is operating solo. the pressure limiter limits the high pressure of the supply reservoir to approximately 9.5 bar and sharp braking of the towing vehicle is possible. When the veh icle is towing a trailer, the trailer is, as described in the earlier application supplied with a maximum pressure of 7.5 bar.
When the vehicle is towing the trailer, the switching point of the pressure limiter is reduced from 9.5 bar to 7.5 bar by means of the adjusting piston 141 by the application of control pressure through the control line 154 to the chamber 153, the control pressure being derived from the compressed air supply to the trailer vehicle. Consequently, the maximum braking of the towing vehicle is reduccd from approximately 95% to 80% in advance for safety, as described in the earlier application.
The safety valve 155 opens whenever, for any reason, the pressure in the line 115 becomes too great.
Should either of the two seals 148 or 149 become untight, a pressure leak may be released by lifting of the hose piece 152 to the outside air without varying the adjusted pressure- and working-stage at the pressure limiter.
As Fig. 1. shows, the pressure limiter according to the invention is very easy to assemble. All regulating parts may be installed in the housing 140 from the adjusting piston side. The simple socket connection between the piston member 137 and the adjusting piston 141 also makes installation easier. Since the adjusting piston 141 on its side facing the piston member 137 is subject to the secondary pressure with as great a surface as it has in the control chamber 153, the secondary pressure can offset the pressure action through the control line 154.
WHAT WE CLAIM IS: 1. A pressure limiter for a compressedair braking system of a motor vehicle which is provided with high-pressure generating and storing means and a working-pressure braking device, which limiter comprises a valve which has a valve seat and a closure member co-operating with the seat and carried by a piston member which is exposed to the pressure to be limited (i.e. the pressure downstream of the seat) and moved thereby to the closed position, and is subjected to the force of an adjustable restoring spring to move the valve to the open position, the piston member being displaceable by means of an adjusting piston, which may be subjected to a control pressure, against the force of the restoring spring in the closing direction of the valve to vary the pressure limited by the valve, the adjusting piston being coupled to the piston member and being sealed with respect to a cylinder bore by two seals received on the adjusting piston, the seals defining therebetween a pressure-relieved intermediate chamber, the pressure to be limited acting on the adjusting piston in a direction opposite to the control pressure.
2. A pressure limiter as claimed in claim 1, in which the cylinder housing is provided with an annular necked-down portion which has a port leading to the intermediate chamber and a resilient hose piece is received over the annular necked-down portion to vent the intermediate chamber to atmosphere in the manner of a non-return valve.
3. A pressure limiter as claimed in claim 1 or 2, in which an end of the adjusting piston facing the piston member has a collar-like coupling means thereon for attaching the adjusting piston to the piston member.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    sion is variable by means of a screw 131. In this manner, the change over point of the pressure at which the valve is closed can be varied.
    A working cylinder 133 is disposed coaxially with the piston member 137 on the housing 140 of the pressure limiter 130 and forms a caplike closure of the housing 140. An adjusting piston 141 is movable in the working cylinder 133 and has a collar-like end portion 142 at its end facing the piston member 137. A caplike coupling element
    145 which is held against a shoulder 143 of the piston member 137 by means of a spring ring 144 is shown in plan view in Fig. 2. It may be seen that it has an oblong hole 146 having an eccentric extension 147. The collar-like end portion of the adjusting piston
    141 may be introduced into the eccentric extension 147 and after centering the adjusting piston 141 in the coupling element 145 during assembly, these two parts are securely fastened to one another.
    The adjusting piston 141 earriestwoannu- lar seals 148 and 145) which are separated from one another by a pressure-relieved intermediate chamber 15 1'. The cap-like closure 133 of the pressure limiter housing
    140 has an annular necked-down portion
    150 which is connected by a port 15 1 to the intermediate chamber 151'. A resilient cylindrical hose piece 152 is inserted over the annular necked-down portion 149 and monitors an outside-air connection of the intermediate chamber 151' in the manner of a non-return valve.
    A chamber 153 above the adjusting piston 141 serves as a control chamber of the pressure limiter and is connected to a control line 154. A safety valve 155 is provided in the piston member 137. This safety valve 155 may however be omitted.
    The pressure limiter operates to a large extent in an identical manner to that described in our earlier patent application No. 45134/75 (Serial No. 1.521 525).
    When the mechanically propelled vehicle is operating solo. the pressure limiter limits the high pressure of the supply reservoir to approximately 9.5 bar and sharp braking of the towing vehicle is possible. When the veh icle is towing a trailer, the trailer is, as described in the earlier application supplied with a maximum pressure of 7.5 bar.
    When the vehicle is towing the trailer, the switching point of the pressure limiter is reduced from 9.5 bar to 7.5 bar by means of the adjusting piston 141 by the application of control pressure through the control line 154 to the chamber 153, the control pressure being derived from the compressed air supply to the trailer vehicle. Consequently, the maximum braking of the towing vehicle is reduccd from approximately 95% to 80% in advance for safety, as described in the earlier application.
    The safety valve 155 opens whenever, for any reason, the pressure in the line 115 becomes too great.
    Should either of the two seals 148 or 149 become untight, a pressure leak may be released by lifting of the hose piece 152 to the outside air without varying the adjusted pressure- and working-stage at the pressure limiter.
    As Fig. 1. shows, the pressure limiter according to the invention is very easy to assemble. All regulating parts may be installed in the housing 140 from the adjusting piston side. The simple socket connection between the piston member 137 and the adjusting piston 141 also makes installation easier. Since the adjusting piston 141 on its side facing the piston member 137 is subject to the secondary pressure with as great a surface as it has in the control chamber 153, the secondary pressure can offset the pressure action through the control line 154.
    WHAT WE CLAIM IS: 1. A pressure limiter for a compressedair braking system of a motor vehicle which is provided with high-pressure generating and storing means and a working-pressure braking device, which limiter comprises a valve which has a valve seat and a closure member co-operating with the seat and carried by a piston member which is exposed to the pressure to be limited (i.e. the pressure downstream of the seat) and moved thereby to the closed position, and is subjected to the force of an adjustable restoring spring to move the valve to the open position, the piston member being displaceable by means of an adjusting piston, which may be subjected to a control pressure, against the force of the restoring spring in the closing direction of the valve to vary the pressure limited by the valve, the adjusting piston being coupled to the piston member and being sealed with respect to a cylinder bore by two seals received on the adjusting piston, the seals defining therebetween a pressure-relieved intermediate chamber, the pressure to be limited acting on the adjusting piston in a direction opposite to the control pressure.
    2. A pressure limiter as claimed in claim 1, in which the cylinder housing is provided with an annular necked-down portion which has a port leading to the intermediate chamber and a resilient hose piece is received over the annular necked-down portion to vent the intermediate chamber to atmosphere in the manner of a non-return valve.
    3. A pressure limiter as claimed in claim 1 or 2, in which an end of the adjusting piston facing the piston member has a collar-like coupling means thereon for attaching the adjusting piston to the piston member.
    3 in which a coupling element is attached to
    the piston member and has an oblong hole with an eccentric extension in which hole the collar of the coupling means of the adjusting piston may be received.
    5. A pressure limiter as claimed in any of claims 1 to 4, in which the adjusting piston has two equal opposed working faces.
    6. A pressure limiter as claimed in any preceding claim in which a relief valve is provided within the piston member.
    7. A pressure limiter constructed substantially as herein described with reference to and as illustrated in the accompanying drawings.
GB1878977A 1976-05-07 1977-05-05 Pressur*e limiters for a compressed-air braking system Expired GB1564566A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19762620135 DE2620135A1 (en) 1974-11-02 1976-05-07 Press. limiting valve for compressed air brakes - has brake press. dependent adjuster for use when pulling trailer

Publications (1)

Publication Number Publication Date
GB1564566A true GB1564566A (en) 1980-04-10

Family

ID=5977265

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1878977A Expired GB1564566A (en) 1976-05-07 1977-05-05 Pressur*e limiters for a compressed-air braking system

Country Status (2)

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CH (1) CH617394A5 (en)
GB (1) GB1564566A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3622213A1 (en) * 1986-07-02 1988-01-07 Teves Gmbh Alfred PRESSURE REGULATION DEVICE, IN PARTICULAR FOR PRESSURE-OPERABLE ACTUATORS

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3622213A1 (en) * 1986-07-02 1988-01-07 Teves Gmbh Alfred PRESSURE REGULATION DEVICE, IN PARTICULAR FOR PRESSURE-OPERABLE ACTUATORS

Also Published As

Publication number Publication date
CH617394A5 (en) 1980-05-30

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PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee