Patent GB-738661-A (GB)
Title: Improvements in or relating to pressure-responsive valves
Inventor: LEE NORMAN
IPC: F16K17/10
Filed: 1952-10-15
Abstract: 738,661. Fluid-pressure servomotor-control systems; valves. KEELAVITE CO., Ltd. Oct. 2, 1953 [Oct. 15, 1952; April 13, 1953], Nos. 25887/52 and 10062/53. Class 135. A pressure-responsive valve assembly which can be adapted to perform different functions such as those of a relief valve, a pressurereducing valve, a flow regulating valve, a bleed valve, or a valve opened and closed under the influence of some controlling pressure comprises essentially a valve housing A, Fig. 1, containing a main valve chamber with cylindrical end portions between which lie flow chambers B<SP>2</SP>, B<SP>3</SP> separated by a cylindrical port or passage B<SP>4</SP> coaxial with and of approximately the same diameter as the end portions, and a main valve member with piston-like end portions C, C<SP>1</SP>, Fig. 4, slidable in the end portions and an intermediate portion C<SP>4</SP> of reduced diameter which when the valve is open extends through the port B<SP>4</SP>, the end portions of the main valve chamber beyond the ends of the valve member constituting pressure chambers F, F<SP>1</SP>, the pressures in which serve to actuate the valve. According to the invention one end of the main valve chamber is closed by a spring assembly and the other end of the main valve chamber is closed by a stop assembly, the spring abutment assembly and the stop assembly being interchangeable in the ends of the main valve chamber. The chamber F communicates by passages C<SP>7</SP>, C' in the main valve member with the flow chamber B3 and the pressure chamber F<SP>1</SP> communicates by a passage H<SP>1</SP> with a relief valve chamber. The chamber F is closed by a plug D with an adjustable stop or alternatively by a plug D bearing a short stop D<SP>1</SP> or one bearing a long stop D<SP>2</SP>, Fig. 4. The chamber F<SP>1</SP> is closed by a loading spring abutment assembly comprising a plug E, a screw-threaded abutment E<SP>1</SP> bearing against one end of a spring E<SP>2</SP>, and a lock-nut E<SP>3</SP>. The piston portions C, C<SP>1</SP> are counterbored to receive the stop D<SP>1</SP> and the spring E<SP>2</SP>. The flow chamber B<SP>3</SP> is connected with a passage B<SP>5</SP> communicating through a passage G<SP>1</SP> with a junction chamber G from which branch three other passages, one being connected to the pressure chamber F<SP>1</SP> through a removable restricted orifice member L, and the other two leading outside the housing and normally being blocked as shown in Fig. 1, by plugs G<SP>5</SP>, G<SP>6</SP>. The relief valve chamber comprises upper and lower ends H<SP>2</SP>, H, Fig. 4, closed respectively by plugs K, J. The plug J has an extension J<SP>1</SP> forming at its upper end a fluid-tight seal with a reduced diameter part H<SP>6</SP> of the relief valve chamber. The extension J<SP>1</SP> has a passage J<SP>2</SP>, the upper end of which forms a seat for a spring- loaded ball valve K<SP>4</SP> in the upper chamber H2. The spring is adjusted by an abutment member K<SP>1</SP> adjustably mounted in the plug K. The chamber H<SP>2</SP> has passages H3, H<SP>4</SP> communicating with the flow chamber B<SP>2</SP> and the outside of the housing A respectively, the passage H<SP>4</SP> being shown in Fig. 1 closed by a removable plug H<SP>5</SP>. The plug D with its stop D<SP>1</SP> or D<SP>2</SP> and the spring abutment assembly with the spring E<SP>2</SP> may be interchanged. Similarly the plug J with its extension J<SP>1</SP> and the plug K with the abutment K<SP>1</SP>, spring K<SP>2</SP>, and ball valve K<SP>4</SP> may be interchanged end for end in the relief valve chamber. On removal of the plug H<SP>5</SP>, the passage H4 may be connected to an external pilot valve or to a selected point in a hydraulic system. In this case the passage H<SP>3</SP> is closed by a plug. The arrangement shown in Fig. 1 operates as a relief valve, the passage B<SP>5</SP> being connected to a high-pressure source, the chamber B<SP>2</SP> being an outflow chamber. The main valve therefore opens when the pressure in the chamber Fl and therefore in the chamber H is sufficient to open the ball valve K<SP>4</SP>. If the passage H<SP>3</SP> is plugged and the passage H<SP>4</SP> open to relief the main valve opens at a pressure independent of that in the outlet chamber B<SP>2</SP>. In a modification, Fig. 2 (not shown), the passage G<SP>1</SP> is closed by a plug and the passage B<SP>5</SP> and chamber G are connected to upstream and downstream sides of an adjustable throttle in a main flow passage so that a predetermined pressure drop across the throttle is maintained as long as the pressure on its downstream side is sufficient to open the valve K<SP>4</SP>. In the case of a reducing valve (Fig. 3, not shown), the plug D with the longer stop D<SP>2</SP> is used so that the main valve is normally open, the passage H<SP>3</SP> is closed by a plug and the passage H<SP>4</SP> is open to relief. The chamber B<SP>2</SP> is connected to a high-pressure source .and a constant pressure determined by the force of the springs E<SP>2</SP>, K<SP>2</SP> is maintained in the outlet B<SP>5</SP>. This arrangement may be modified as in Fig. 4 by inserting a screwthreaded orifice member P in the passage B so that the junction chamber G communicates with the outlet side of the orifice member. In this way a predetermined pressure drop is maintained across the orifice member P and the pressure on the outlet side of the member P is limited by the valve K<SP>4</SP>. Fig. 5 shows a further modification in which the plug D and stop D<SP>2</SP> are interchanged with the plug E and spring E<SP>2</SP> as compared with Fig. 1, and an orifice member P is arranged in the inlet passage B<SP>5</SP>. By this arrangement, a predetermined pressure is maintained across the orifice member P and the pressure which can occur in abnormal circumstances in the chamber B<SP>3</SP> is limited to that which causes the valve K4 to lift. In a similar arrangement the passage H4 is connected to a source of fluid pressure and the passage H3 is plugged. In each of the three last-mentioned arrangements, the orifice member P may be replaced by a fixed or adjustable throttle external to the housing A and upstream of the passage B<SP>5</SP>, the passage G<SP>1</SP> being plugged and the passage G3 open to the inlet side of such throttle. Fig. 10 shows a pilot controlled relief valve in which the main valve C, C<SP>1</SP> opens when the pressure in the inlet flow chamber B2 is sufficient to open the relief or pilot valve K4. This valve assembly may be adapted to maintain a constant pressure in a conduit between a hydraulic motor and a throttle on its outlet side by venting the pressure on the inlet side of the motor. In Fig. 12, the main valve C, C<SP>1</SP> is normally kept open by the stop D2 and the caps J, K are reversed as compared with Fig. 1. This arrangement maintains a predetermined pressure drop across the orifice member P in the outlet B<SP>5</SP> and also limits the pressure in the inlet chamber B<SP>2</SP>. The orifice member P may be replaced by an external throttle if the passage G<SP>1</SP> is plugged and the chamber G open to the outlet of the throttle. In a further arrangement (Fig. 15, not shown) the main valve which is normally open is closed when an external pressure which is sufficient to open the relief valve K<SP>4</SP> is applied to the passage H<SP>4</SP>. In this case the chambers F, G are connected to a relief passage. In a modification of this arrangement the stop D<SP>2</SP> is replaced by the shorter stop so that the main valve is normally closed. In a further arrangement (Fig. 17, not shown), the passage C<SP>7</SP> is closed by a plug and the chambers F and G are directly connected to an external source of pressure, e.g. through a pilot valve so that the main valve closes when the pressure of the external source is sufficient to open the relief valve K4. This arrangement may be modified (Fig. 19, not shown) by replacing the stop D<SP>2</SP> by the stop D<SP>1</SP> so that the main valve is normally closed. In a further arrangement similar to Fig. 10 (Fig. 18, not shown) the passages C<SP>7</SP> and G<SP>1</SP> are plugged and the chambers F, G are connected to a relief passage so that the main valve operates to relief pressure in the inlet B<SP>2</SP> when the pressure therein is sufficient to open the valve K4. Fig. 20 shows a construction in which relief valve is omitted. The main valve is adapted to by-pass pressure fluid from the inlet side of a hydraulic motor R<SP>1</SP> whenever the pressure drop across a throttle R<SP>2</SP> on the outlet side of the motor exceeds a predetermined amount determined by the spring E<SP>2</SP>. The same construction may be used as a relief valve by interchanging the cap E and spring E<SP>2</SP> with the stop D<SP>1</SP>, placing the orifice member L in the passage G<SP>1</SP> and connecting the passage G<SP>3</SP> to an adjustably loaded external relief valve.