US3566920A

US3566920A - Fluid control valves

Info

Publication number: US3566920A
Authority: US
Inventors: Charles G Stewart
Original assignee: Girling Ltd
Current assignee: Girling Ltd
Priority date: 1968-01-24
Filing date: 1969-01-16
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02
Also published as: NL6900659A; BE726499A; CS150970B2; FR2000687A1; FR2000687B1; DE1903104A1; GB1247675A; JPS4838721B1

Abstract

In a fluid control valve in which a double-beat valve head is adapted to engage alternatively with opposed axially spaced valve seats located respectively between inlet and outlet ports in the valve body and between the outlet port and a further port, the position of the valve head is controlled by a diaphragm which is exposed on its underside to the inlet pressure and on its upper side to the pressure in a chamber which is connected to atmosphere through a passage in the valve body coaxial with the valve on energization of a solenoid actuating a pilot valve which normally closes the passage.

Description

United States Patent 72] Inventor Charles G. Stewart Solihull, England [21] Appl. No. 791,602 [22] Filed Jan. 16, 1969 [45] Patented Mar. 2, 1971 [73] Assignee Girling Limited I Birmingham, England [32] Priority Jan. 24, 1968 [33] Great Britain [31] 3704 [54] FLUID CONTROL VALVES UNITED STATES PATENTS 2,870,986 l/l959 Vargo 251/45 2,896,579 7/1959 Campbell 137/625.6 2,993,676 7/1961 Dahl 251/45X 2,994,343 8/1961 Banks 251/362X 3,188,148 6/1965 Eaton l37/625.64X 3,326,239 6/1967 Saint-Joanis et a1. 137/625.66 FOREIGN PATENTS 740,225 1 l/1955 Great Britain 137/625.64

Primary Examiner-Henry T. Klinksiek Attorney-Kemon, Palmer & Estabrook ABSTRACT: In a fluid control valve in which a double-beat valve head is adapted to engage alternatively with opposed axially spaced valve seats located respectively between inlet and outlet ports in the valve body and between the outlet port and a further port, the position of the valve head is controlled by a diaphragm which is exposed on its underside to the inlet pressure and on its upper side to the pressure in a chamber which is connected to atmosphere through a passage in the valve 1,521,355 12/1924 Burns 251/45 body coaxial with the valve on energization of a solenoid ac- 2,5 87,357 2/1952 McPherson 137/625.64 tuating a pilot valve which normally closes the passage.

,PATENTEDMAR 2197: $566,920

SHEET 1 OF 2 PATENTEUHAR 2|97| 3566820 SHEET 2 0F 2 m VE A/TM WWW am Mm, min/ 'M FLUID CONTROL VALVES This invention relates to improvements in fluid control valves of the kind in which a double-beat valve head is adapted to engage alternatively with opposed axially spaced seatings located respectively between inlet and outlet passages in the valve body and between the outlet passage and a further port or passage, the position of the valve head being controlled by a diaphragm exposed on its underside to the inlet pressure and on the upper side to the pressure in a chamber which is in restricted communication with the inlet passage and is connected to atmosphere on opening of a pilot valve controlled by electromagnetic means.

One object of our invention is to provide an improved valve of that kind which is particularly adapted for use in a fluid pressure braking system for rail or other vehicles incorporating means for correcting slipping of the wheels when braking.

The invention comprises a valve of the kind set forth in which the chamber above thediaphragm is adapted to be connected to atmosphere through a passage in the valve body which is coaxial with the valve and is controlled by a pilot valve which normally engages and closes the upper end of the passage and is opened on energization of a solenoid.

The pilot valve is conveniently formed by an extension of the armature of the solenoid which may engage directly with a seat at the upper end of the passage or may act on a ball cooperating with the seat.

When the pilot valve is closed the underside of the diaphragm is exposed to the inlet pressure but a bleed orifice in the diaphragm maintains the same pressure in the chamber above the diaphragm so that the diaphragm is balanced, the valve being maintained by a spring in a position in which there is free flow between the inlet and outlet passages.

One form of valve in accordance with the invention and a modification are illustrated by way of example in the accompanying drawings in which FIG. 1 is a side elevation of the valve;

P10. 2 is a vertical section of the valve on the line 2-2 of FIG. and

FIG. 3 is a fragmentary section pilot valve.

In the valve illustrated the body of the valve comprises three main parts, a lower body part 10, and upper body part 11, and a cover 12 forming a housing for an operating solenoid. All three parts are conveniently formed as diecastings.

The lower body part incorporates an inlet 13 leading into a chamber 14 separated by a partition 15 from a lower chamber 16 out of which leads an outlet 17. A central opening in the partition houses an insert 18 which is a press fit in the opening. The insert is formed with a central axial bore for the valve stem and a ring of ports 19, and it has on its lower end an annular tapered extension of which the lower extremity forms a valve seat 21. A second coaxial valve seat 22 spaced from the seat 21 is formed around a central exhaust passage 23 in a fitting 24 secured by bolts against the bottom of the lower body part and closing the lower end of the chamber 16. Operating between the two valve seats is a double-beat valve head 25 secured by a nut 26 on the lower end of a spindle 27. A moulded rubber or other compressible washer 28 is located in an annular recess in the bottom face of the head for engagement with the exhaust seat 22. A similar washer 29 fits over a showing a modified form of 4 short spigot on the upper face of the valve head on which it is retained by a rigid metal washer 30 which is clamped against a shoulder on the stem 27 when the nut 26 is tightened. The diameter of the washer 30 is slightly less than the internal diameter of the valve seat 21.

The valve head is biassed towards the exhaust seat by a compression spring31, located between the valve head and the partition 15.

The axial length of the valve assembly is only slightly less than the axial spacing between the valve seats.

The valve spindle 27 extends upwardly through the chamber 14 and is secured to the center of a diaphragm 32 which closes the upper end of the chamber and of which the peripheral edge is clamped between cooperating flanges on the

body parts

10 and 11 which are secured together by bolts 33. The central part of the diaphragm is received between two spacers 34, 35 which are clamped between a collar 36 on the valve spindle and a nut 37 secured on to the spindle above the diaphragm assembly. A small bleed orifice 38 is formed in the diaphragm and openings 39 are formed in the spacers in alignment with the orifice, a filter 40 being located in an annular recess in the lower spacer 35.

The bleed orifice provides restricted communication between the chamber 14 below the diaphragm and a chamber 41 above the diaphragm which is formed by a recess in the underside of the body part 11 and is made of as small volume as possible consistent with allowing for the necessary vertical movement of the diaphragm assembly.

The upper extremity of the valve spindle, which is of reduced diameter and is formed with one or more longitudinal grooves 42, extends upwardly through the chamber 41 and is adapted to slide in a cylindrical recess 43 in a bush 44 located in a stepped axial opening in an upward extension 45 of the body part 11. The bush is moulded from polytetrafluoroethylene (P.T.F.E.) and is secured in the extension 45 by a locking pin 46. The recess 43 in the bush leads by way of an axial passage 47 of small bore into a recess 48 in the upper end of the bush. The passage 47 is normally closed by a stainless steel bass valve 49 which is held in engagement with a coned seat at the upper end of the passage by a reduced extension 51 of the armature 52 of a solenoid 53. The closure could be by a coned lower end of the extension 51 closing the passage directly, as described for the extension 62 in FIG. 3 below. The ball or the coned lower end in conjunction with the seat at the upper end of the passage 47 forms the pilot valve which controls the operation of the main valve. The armature is biassed downwardly by a light spring 54 to hold the ball valve closed. A disc 55 is fixed the the reduced lower part of the armature and cooperates with a spring ring 56 located in the cover to form a stop which keeps the armature in place while the valve is being assembled. it also provides an anchorage for a rubber diaphragm or seal 57 which prevents foreign matter from getting into the solenoid. The annular space in the cover around the extension 45 is in communication with atmosphere through an opening 58 in the cover.

In the normal operation of the valve the parts are in the positions shown in FIG. 2.

The pilot valve is closed and the valve head is held in engagement with the lower or exhaust seat 22 by the spring 31 so that the exhaust passage 23 is closed off and there is free communication between the inlet 13 and the outlet 17.

The underside of the diaphragm is exposed to the inlet pressure but fluid passing through the bleed hole 38 in the diaphragm maintains the same pressure in the space above the diaphragm so that the diaphragm is balanced and the only force acting on the valve head is that exerted by the spring 31.

When the pilot valve is opened by energization of the solenoid the space above the diaphragm is put into communication with atmosphere by way of the opening 58, the passage 47 and the groove 42 in the upper end of the valve spindle. The inlet pressure acting on the underside of the diaphragm then moves the valve head up into engagement with the upper valve seat 21 so that communication between the inlet and outlet is cut off and the outlet is put into communication with exhaust through the lower valve seat 22 and the passage 23.

As the valve head moves upwardly towards the seat 21 the washer 30 enters the opening in the valve seat and restricts the flow of fluid between the inlet and outlet passages before the head engages and closes the seat.

The object of this is to eliminate flutter of the valve as it closes if the inertia of the valve is insufficient to allow it to close against the seat without flutter.

In the modified form of the pilot valve shown in FIG. 3 a

passage 61 of small cross-sectional area, corresponding to the passage 47, is formed in the upper end of the body part 11 itself. The passage 61 is adapted to be closed by the coned lower end of a reduced downward extension 62 of the armature 52 ofthe solenoid.

In the application of the improved valve to a fluid pressure braking system for rail vehicles the inlet will be connected to a source of air under pressure, the outlet to a brake-applying cylinder or cylinders, and the further outlet or passage to exhaust.

The energization of the solenoid actuating the pilot valve is effected by an electric signal from a unit sensitive to the rate of change in the speed of rotation of a braked wheel, and when the wheel is decelerated at an excessive rate the pilot valve is opened and the valve cuts off the supply of fluid under pressure to the brake-applying cylinder and connects it to exhaust so that the pressure in the cylinder is rapidly reduced and the brake is released before the wheel locks.

The electric current for energizing the solenoid is preferably supplied by a generator mounted on the vehicle itself and driven by a wheel so that the system is self-contained and independent of any external power source, the generator charging any convenient form of battery or capacitor.

With that arrangement the current requirement of the solenoid has to be kept low, and for this reason a small pilot valve orifice is used and the volume of the chamber above the diaphragm is made as small as possible in order to obtain a rapid response from the valve. For the same reason it is desirable to keep the axial spacing between the valve seats to a minimum.

1 claim:

1. A fluid control valve in which a double-beat valve head mounted on a spindle is adapted to engage alternatively with opposed axially spaced valve seats located respectively between inlet and ,outlet ports in the valve body and between the outlet port and a further port, and the position of the valve head is controlled by a diaphragm attached to said spindle and exposed on its underside to the inlet pressure and on its upper side to the pressure in a chamber which is in restricted communication with the inlet port and has a connection to atmosphere controlled by a pilot valve, wherein said connection comprises a passage in the valve body coaxial with the valve spindle, and said passage is normally closed by a pilot valve member actuated by the armature of a solenoid located in the valve body, energization of said solenoid opening the pilot valve.

2. A fluid control valve as in claim 1 wherein said passage is formed in a bush fixed in an opening in the upper part of the valve body, the upper end of the passage which is of small bore forms a seat for a ball, and the ball is normally held in engagement with said seat by an extension of the armature of the solenoid which is biassed by a light spring towards the bush.

3. A fluid control valve as in claim 2 wherein said bush is moulded from polytetrafluorethylene.

4. A fluid control valve as in claim 1 wherein said passage is formed in the upper part of the valve body and the upper end of the passage which is of a small bore forms a seat adapted to be engaged by the coned lower end of a downward extension of the armature of the solenoid.

5. A fluid control valve as set forth in claim 1 wherein said diaphragm is formed with an orifice and provides communication between said chamber and passage.

6. A fluid control valve as set forth in claim 1 wherein said valve body has a bush therein and said spindle terminates in a reduced end portion, said reduced end portion being slidably guided in a recess provided in said bush, said bush and recess being coaxial with said spindle.

7. A fluid control valve as set forth in claim 6 wherein said reduced end portion is formed with one or more longitudinally extending grooves to provide communication between said chamber and recess.

Claims

1. A fluid control valve in which a double-beat valve head mounted on a spindle is adapted to engage alternatively with opposed axially spaced valve seats located respectively between inlet and outlet ports in the valve body and between the outlet port and a further port, and the position of the valve head is controlled by a diaphragm attached to said spindle and exposed on its underside to the inlet pressure and on its upper side to the pressure in a chamber which is in restricted communication with the inlet port and has a connection to atmosphere controlled by a pilot valve, wherein said connection comprises a passage in the valve body coaxial with the valve spindle, and said passage is normally closed by a pilot valve member actuated by the armature of a solenoid located in the valve body, energization of said solenoid opening the pilot valve.