GB2076122A - Fluid pressure control valves - Google Patents
Fluid pressure control valves Download PDFInfo
- Publication number
- GB2076122A GB2076122A GB8111942A GB8111942A GB2076122A GB 2076122 A GB2076122 A GB 2076122A GB 8111942 A GB8111942 A GB 8111942A GB 8111942 A GB8111942 A GB 8111942A GB 2076122 A GB2076122 A GB 2076122A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fluid pressure
- valve according
- port
- counter
- coil
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D16/00—Control of fluid pressure
- G05D16/20—Control of fluid pressure characterised by the use of electric means
- G05D16/2086—Control of fluid pressure characterised by the use of electric means without direct action of electric energy on the controlling means
-
- 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
- B60T15/00—Construction arrangement, or operation of valves incorporated in power brake systems and not covered by groups B60T11/00 or B60T13/00
- B60T15/02—Application and release valves
- B60T15/025—Electrically controlled valves
- B60T15/027—Electrically controlled valves in pneumatic systems
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Valves And Accessory Devices For Braking Systems (AREA)
Abstract
The pressure of fluid passing from a throttled inlet 2 to an outlet 4 is controlled by a vent valve 12 which is biassed closed by a pivoted beam 25 subject to a variable electromagnetic force. The beam is statically counter-balanced by weights 26 and is supported by a resilient metal strip which allows limited angular movement of the beam about its support at 24. The combination of static balance and resilient support renders the valve substantially insensitive to shock forces acting through the support point. <IMAGE>
Description
SPECIFICATION
Fluid pressure control valves
This invention relates to fluid pressure control valves and relates especially to fluid pressure control valves which are suitabie for use in installations such as required for braking systems of vehicles and which may be subject to violent mechanical vibrations or shock.
In the Specification of U.K. Patent
No. 1,174,243 there is described and claimed a fluid pressure control valve having a restricted flow inlet port and an outlet port, an exhaust port providing a valve seat and a throttle element movable towards and away from the valve seat thereby to effect a varying degree of throttling to the passage of fluid through the valve seat a cantilever mounted leaf spring, the free end of which is operatively engageable by the throttling element and loading means by which the free end of the leaf spring can be loaded such that in operation of the valve when a fluid pressure of predetermined value pertains at the input port, the value of the fluid pressure pertaining to the output port is dependent upon the rate of escape of fluid through the valve seat which rate is in turn determined by the degree of throttling effected by the throttling element consequent upon the degree of loading of the leaf spring by said loading means.
Control valves such as the foregoing have been found to be sensitive to vibrations and shock when employed in fluid pressure operable braking systems for controlling a braking pressure and a satisfactory solution has been employed which makes use of an hydraulic damper to resist deflection of the leaf spring due to such shocks and vibrations without appreciably affecting the normal mean deflection due to a steady electromagnetic loading of the leaf spring.
It has been found, however, that with such a damping system, certain forms of shock can produce undesired temporary deflection of the leaf spring and the need to provide seals to contain the damping fluid has been considered to be a disadvantage owing to the possibility of eventual leakage. It is therefore an object of the present invention to remove or substantially reduce such shortcomings.
According to the present invention, there is provided a fluid pressure control valve having a restricted fluid flow inlet port, a vent port provided with a variable throttle arrangement and a fluid pressure outlet port connected to a region between the inlet port and the vent port, the variable throttle arrangement comprising a forceapplying means carried to one side of a support point of a substantially rigid beam which is resiliently supported for angular movement about said support point and having counter-balancing mass at the other side thereof to render the valve substantially insensitive to shock forces acting through said support point.
In order that the invention may be more clearly understood and readily carried into effect, the same will be further described by way of example with reference to the accompanying drawing of which
Fig. 1 illustrates in diagrammatical form an electro-pneumatic converter valve embodying the present invention; and
Fig. 2 illustrates the manner of resiliently supporting the beam of the device for angular movement.
In Fig. 1 is shown a block 1 which houses the pneumatic parts of the electro-pneumatic converter valve and comprises a pressure input port 2, a vent port 3 and a fluid pressure output port 4 connected to a region 5 between the restricted input port 2 and the variably vented port 3. The source of fluid pressure for the electropneumatic converter is connected at a port 6 from which it is applied via a pressure regulating valve having a valve closure member 7 to a chamber 8.
Control means for the pressure-regulating valve 7 comprises a diaphragm 9 adjustably spring-loaded by a spring 10 with adjustment screw 11. The variable throttle arrangement for the vent port 3 is provided by virtue of a valve member 12 in the form of a ball which, in the position shown, closes the region 5 from atmosphere. The details of the components in block 1 are only shown diagrammatically because this position of the valve is almost identical to the valve described and shown in Fig. 1 of United Kingdom Specification No.1,174,243.
In order to urge the bail 12 against its seat to close-off the region 5, an electro-magnetically operable loading means is provided, the loading produced by which is dependent upon the current flowing in a cylindrical coil 1 3 movable axially in an annular space 14 between an annular pole 1 5 and an inner cylindrical pole 1 6 of a permanent magnet arrangement. The permanent magnet arrangement comprises a cylindrical permanent magnet 1 7 clamped between a flange 1 8 of the central pole piece 16 and the annular pole piece 1 5 by clamping screws, one of which is shown at 19, through a non magnetic pillar 20. The whole magnetic assembly is thereby mounted on the block 1.The cylindrical coil 1 3 is wound upon a coil-former 21 carried at its centre on a supporting arrangement comprising a central boss 22 in a non-magnetic support plate 23 carried to one side of the support point 24 of a rigid beam 25.
The other side of the beam 25 with respect to the support point 24, carries static counter-balancing weights in the form of washers 26 or the like.
Optionally, moreover, a biasing spring 27 can be included beneath the beam 25 and retained between the mounting stud 28 for the counterbalancing weights, on the one hand, and a recess 29 in the upper surface of a base member 1. The bias on the spring may be varied by adjustment of the position of a spring follower 27a on one end of the stud 28. This spring is included as such an option in order to modify the operating characteristics of the valve.
The manner of resiliently supporting the beam 25 for angular movement is illustrated in Fig. 2
wherein the beam 25 is shown together with the
counter-balancing weights 26. The support point
for the beam is fixed to the underside of a pair of
blocks 30 and 31 which clamp the middle portion
of a strip of spring-metal 32, the ends of which are
held in support blocks 34 and 35 which in turn are
mounted on the base block 1 of the electro
pneumatic converter. The small amount of angular
movement which is required of the beam 25 is
thereby permitted by the portions of the spring
material strip 32 between the outer blocks 34 and
35 and the blocks 31 and 32 beneath which the
beam is supported.Furthermore, in assembling
the device, the counter-weights 26 are adjusted to
substantially counter-balance the mass of the coil
assembly which is carried at the other side of the
beam with reference to the support point 24.
Preferably, this balancing is effected before final
assembly of the device.
In operation of the electro-pneumatic converter
of Fig. 1, fluid pressure is supplied from a reservoir
to the port 6 from whence it passes via the valve 7
into the small reservoir 8 provided in the base
block of the valve. This pressure acts on the upper side of the diaphragm 9 and upon reaching a value
at which the spring 10 is sufficiently deflected to
permit closure of the valve 7, the pressure in the
reservoir 8 ceases to increase further. The
pressure thus established in the reservoir 8 is
maintained from 6 and communicated via the
restricted orifice of input port 2 to the region 5
with a pressure drop which is determined by the
degree of throttling provided by the member 12
restricting vent port 3.
Assuming that the device is required to produce
an output pressure which is variable in proportion
to the current which is fed to the coil 13, the
optional spring 27 will be excluded from the
assembly and the sense of energisation of the coil
13 will be such as to cause downward urging of
the member 12 with increasing current.
Correspondingly progressively increasing force on
the member 12 therefore progressively increases
the pressure which is necessary to effect
unseating of 12 and this pressure appears as the
output pressure at port 4.
Assuming now that the device is required to
operate as an inverse device or, in braking
parlance, in energise-to-release mode, a suitable
spring 27 is included and, under these conditions,
with zero current applied to the coils 13, the
output pressure can approximate to the
predetermined pressure of the reservoir 8 since
there will be negligible pressure drop via the
restriction 2 and the vent valve 3.
With increasing current in the coil 13, the
thrust exerted by the spring 27 acting via the
beam 25 downwardly on the member 12, is
increasingly relieved by increasing current and
therefore progressively greater pressure drop
occurs across the restriction 2 to produce a
progressively reducing pressure in the region 5
which appears at the output port 4.
It will be appreciated that the device operates
in the same manner as the above-acknowledged previous device to the extent that the output pressure at the port 4 is the result of sharing of pressure drop of the pressure 8 between the input restrictive port 2 and the variable vent port 3.
The spring 27 exerts through the pivoted beam 25 a downward thrust on ball 12 tending to increase the output pressure at port 4. In an alternatively modified construction this downward thrust is provided by a twist in the spring strip 32 in the appropriate sense.
If the fluctuations in the pressure of the fluid supply connected to port 6 are relatively small then the pressure-regulating valve 7 comprising diaphragm 9, spring 10 and adjusting screw 11, and the chamber 8 may be omitted in which case port 6 is connected directly to the restricted port 2.
By virtue of the mounting arrangement for tilTe energising coil 13 on one side of the pivot point of a beam resiliently supported for angular movement about the pivot point and the other side of which beam is counter-balanced by the weights 26, vertical disturbances acting on the assembly produce negligible intermittent variations of the force on the member 12 and therefore the output pressure remains unaffected.
Since, in railway braking applications, either in locomotives or on rolling stock, it is normally possible to mount the assembly such that whilst it may be subjected to vertical and horizontai shocks from any direction to which it is insensitive, rotational shocks are at least rare if not totally non-existent in normal operation and therefore the electro-pneumatic converter described is extremely reliable for this particular application and will find application in other fields where a reliable electro-pneumatic converter is required which is not susceptible to shocks or vibrations.
Claims (10)
1. A fluid pressure control valve having a restricted fluid flow inlet port, a vent port provided with a variable throttle arrangement and a fluid pressure outlet port connected to a region between the inlet port and the vent port, the variable throttle arrangement comprising a force applying means carried to one side of a support point of a substantially rigid beam which is resiliently supported for angular movement about said support point and has a counter-balancing mass at the other side thereof to render the valve substantially insensitive to shock forces acting through the support point.
2. A fluid pressure control valve according to claim 1 in which said resilient support is provided by a strip of spring metal fixed at right angles to said beam and rigidly held at its outer ends so as to permit limited angular movement of said beam about said support.
3. A fluid pressure control valve according to claim 1 or claim 2 in which said counter-balancing mass is in the form of a plurality of easily removable weights.
4. A fluid pressure valve according to any preceding claim having a biassing spring located between said beam and fixed structure and at the end of the beam where said counter-balancing weights are located, so as to modify the operating characteristics of the valve.
5. A fluid pressure valve according to claim 4, in which said biassing spring has means to vary its bias.
6. A fluid pressure valve according to any preceding claim in which said force applying means is in the form of an electromagnetic coil attached to said beam and located in the field of a permanent magnet.
7. A fluid pressure valve according to claim 6 and having the coil so arranged that increasing current will urge the coil downwardly so as to increase the pressure on the variable throttle thereby increasing the pressure at the output port.
8. A fluid pressure valve according to claim 6 and having the coil so arranged that increasing current decreases the pressure on the beam.
9. A fluid pressure valve according to any preceding claim and incorporated in a railway braking system on a locomotive or on rolling stock.
10. A fluid pressure valve substantially as hereinbefore particularly described and as illustrated in the accompanying drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8111942A GB2076122A (en) | 1980-05-16 | 1981-04-15 | Fluid pressure control valves |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8016405 | 1980-05-16 | ||
GB8111942A GB2076122A (en) | 1980-05-16 | 1981-04-15 | Fluid pressure control valves |
Publications (1)
Publication Number | Publication Date |
---|---|
GB2076122A true GB2076122A (en) | 1981-11-25 |
Family
ID=26275555
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8111942A Withdrawn GB2076122A (en) | 1980-05-16 | 1981-04-15 | Fluid pressure control valves |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2076122A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2133504A (en) * | 1982-12-30 | 1984-07-25 | Westinghouse Brake & Signal | Fluid pressure control valve |
-
1981
- 1981-04-15 GB GB8111942A patent/GB2076122A/en not_active Withdrawn
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2133504A (en) * | 1982-12-30 | 1984-07-25 | Westinghouse Brake & Signal | Fluid pressure control valve |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |