Control system for slide valves to avoid mechanical stress

Abstract

A fluid pressure controlled spool valve minimizes wear or adhesion caused by the tilted orientation of a pressure plate that forces a boss of a valve core shaft to wear or adhere to the inner facing surface of a cylindrical barrel supporting the valve core shaft. A permanent magnet is mounted on the pressure plate. A round head composed of a ferromagnetic material is formed on the end of the valve core shaft and is configured to be magnetically attracted to the permanent magnet. When the pressure plate and the magnet are tilted relative to the axis of the valve core shaft, the magnetic attraction force vector generated on the round head of the valve core shaft remains coaxial with the axis of the valve core shaft.

Description

Technical Field

[0001] The disclosed invention relates to a sliding valve. Background Art

[0002] Sliding valves are used to control the direction of flow of fluids in various applications such as automotive power steering and inkjet printing. Sliding valves include a plunger-shaped spool shaft that slides within a cylindrical barrel that has ports cut into the sides of the barrel. Blockage of the ports is provided by lands or full-bore sections on the spool shaft that are separated by narrower sections that provide port interconnection through the cylindrical barrel. Seals are located between the ports and at the outer ends of the cylindrical barrel beyond the outermost ports. The sliding action of the spool shaft can be controlled by an electromechanical solenoid or by pneumatics or hydraulics.

[0003] In pneumatic or hydraulic control, a control fluid pressure signal is introduced into a control fluid chamber of a valve housing, which is separated from a second chamber by a flexible membrane. A pressure plate located in the second chamber is adjacent to the flexible membrane and is mechanically connected to one end of the valve core shaft. A coil spring located in the second chamber maintains a spring force on the pressure plate directed toward the flexible membrane. As the control fluid pressure signal increases in the control fluid chamber, the flexible membrane expands into the second chamber, thereby compressing the pressure plate and moving it into the second chamber, causing the valve core shaft to slide toward the open position. Alternatively, as the control fluid pressure signal decreases in the control fluid chamber, the flexible membrane retracts from the second chamber, pulling the pressure plate, which in turn pulls the mechanical connection to the valve core shaft, causing the valve core shaft to slide toward the closed position.

[0004] A problem with pneumatically or hydraulically controlled spool valves is that as the flexible diaphragm expands and retracts due to changes in the control fluid pressure signal, the pressure plate and its mechanical connection to the valve core shaft may tilt relative to the axis of the cylindrical barrel. The tilted orientation of the pressure plate and its mechanical connection may cause the boss or full-bore portion on the valve core shaft to wear or adhere to the inner facing surface of the cylindrical barrel, resulting in eventual leakage of the working fluid around the boss, thereby limiting the service life of the spool valve.

[0005] What is needed is a design for a pneumatically or hydraulically controlled spool valve that minimizes wear or sticking caused by the angled orientation of a pressure plate and its mechanical connection. Summary of the invention

[0006] According to an exemplary embodiment of the present invention, a pneumatic or hydraulically controlled sliding valve minimizes wear or adhesion caused by the tilted orientation of the pressure plate, which forces the boss of the valve core shaft to wear or adhere to the inner facing surface of the cylindrical barrel supporting the valve core shaft. A permanent magnet is mounted on the pressure plate in the inner chamber. The round head formed on the end of the valve core shaft is composed of a ferromagnetic material and is configured to be magnetically attracted to the permanent magnet. According to the present invention, when the pressure plate and the magnet are tilted relative to the axis of the valve core shaft, the magnetic attraction vector generated on the round head of the valve core shaft remains coaxial with the axis of the valve core shaft. When the pressure of the control fluid decreases, the attraction vector generated on the round head of the valve core shaft remains coaxial with the axis of the valve core shaft to minimize wear or adhesion in the barrel of the sliding valve caused by the tilted orientation of the pressure plate. When the pressure of the control fluid is increasing, pushing the magnet toward the round head of the valve core shaft, the force vector generated on the round head of the valve core shaft remains coaxial with the axis of the valve core shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is an exemplary system diagram according to an embodiment of the present invention, showing a control system for a spool valve, which receives a control fluid pressure signal to adjust a valve core shaft of the spool valve to guide working fluid from a supply system through an output port of the spool valve to a double-acting hydraulic actuator.

[0008] Figure 2 is a side cross-sectional view of a control system for a spool valve, wherein the spool shaft is positioned to cause working fluid to flow out of the Y2 port, wherein the working fluid at the Y1 output port is at zero pressure, and the working fluid at the Y2 output port is at supply port pressure. The figure shows a permanent magnet mounted on a pressure plate in an internal chamber and a round head formed on the end of the spool shaft, which is configured to be magnetically attracted to the permanent magnet. According to the present invention, if the pressure plate is tilted relative to the axis of the spool shaft, the magnetic attraction force vector generated on the round head of the spool shaft remains coaxial with the axis of the spool shaft to minimize wear or sticking in the barrel of the spool valve.

[0009] Figure 3 According to an embodiment of the present invention, Figure 2 A side cross-sectional view of a control system of a spool valve, wherein a control fluid pressure signal is increased to adjust a valve core shaft of the spool valve to be located at a cross point where the working fluid has equal pressure at the Y1 port and the Y2 port.

[0010] Figure 4 According to an embodiment of the present invention, Figure 3 A side cross-sectional view of a control system of a spool valve, wherein the control fluid pressure signal is further increased to adjust the valve core shaft of the spool valve to a position where the working fluid at the Y2 output port is at zero pressure and the working fluid at the Y1 output port is at a supply port pressure.

[0011] Figure 5A A pressure plate oriented perpendicular to the shaft axis is shown according to an embodiment of the present invention, and the magnetic attraction force vector generated on the rounded tip of the valve core shaft remains coaxial with the shaft axis to minimize wear or sticking in the barrel of the sliding valve.

[0012] Figure 5B A pressure plate oriented to be tilted upward relative to the shaft axis is shown according to an embodiment of the present invention, and the magnetic attraction force vector generated on the rounded tip of the valve core shaft remains coaxial with the shaft axis to minimize wear or sticking in the barrel of the sliding valve.

[0013] Figure 5C A pressure plate oriented downwardly angled relative to the shaft axis is shown according to an embodiment of the present invention, and the magnetic attraction force vector generated on the rounded end of the valve core shaft remains coaxial with the shaft axis to minimize wear or sticking in the barrel of the sliding valve.

[0014] Figure 6 is a three-dimensional side cross-sectional view of a control system for a spool valve, showing exhaust ports E1 and E2 for the spool valve.

[0015] Figure 7 is a three-dimensional side view of the spool valve showing the control fluid pressure signal port, the working fluid input ports Y1 and Y2, the working fluid supply port, and the working fluid exhaust port for the spool valve. DETAILED DESCRIPTION

[0016] Figure 1 1 is an example system diagram showing a control system for a spool valve 100 that receives a control fluid pressure signal 105 introduced at a control input port 120 into a control fluid chamber 122 of a valve housing 102, which is separated from an internal second chamber by a flexible membrane. As the pressure of the control fluid 105 changes in the first chamber 122, a valve core shaft 125 slides within the cylindrical barrel of the housing 102, thereby interconnecting or blocking ports Y1 and Y2, supply port S, and a discharge port opened in the side of the cylindrical barrel. Blockage of the ports is provided by bosses or full-bore portions on the valve core shaft 125, which are separated by narrower portions that provide port interconnection through the cylindrical barrel. Seals are located between the ports and at the outer end of the cylindrical barrel beyond the outermost discharge port. The sliding action of the valve core shaft 125 is controlled by a pneumatic or hydraulic control fluid pressure signal 105.

[0017] As the control fluid pressure signal 105 increases in the control fluid chamber 122, the flexible membrane expands into the second chamber, compressing the pressure plate and moving it into the second chamber, causing the valve core shaft 125 to slide to connect port Y2 to the supply port S and Y1 to the exhaust port. The working fluid from the supply system 104 flows through the interconnected supply port S and port Y2 to the port 108 of the double-acting hydraulic actuator 106, thereby pushing the piston 112 in the downward direction shown in the figure. The working fluid returning from the port 110 of the double-acting hydraulic actuator 106 flows through the interconnected port Y1 and the exhaust port supply of the spool valve 100.

[0018] Figure 2 1 is a side cross-sectional view of a control system for the spool valve 100. The spool shaft 125 is positioned in the control fluid chamber 122 by the control fluid pressure signal 105 to connect the supply port S to the Y2 port and the Y1 port to the exhaust port E1. The working fluid at the Y1 output port is at zero pressure, and the working fluid at the Y2 output port is at the pressure of the supply port S. The figure shows a permanent magnet 130 mounted on a pressure plate 128 in the inner second chamber 124 and a round head 132 formed on the end of the spool shaft 125, which is configured to be magnetically attracted to the permanent magnet 130. According to the present invention, if the pressure plate 128 is tilted relative to the axis of the spool shaft 125, the magnetic attraction force vector generated on the round head 132 of the spool shaft 125 remains coaxial with the axis of the spool shaft 125 to minimize wear or adhesion in the cylindrical barrel of the spool valve 100.

[0019] The round head 132 formed on the end of the valve core shaft 125 may be composed of a ferromagnetic material, such as an alloy of iron, cobalt or nickel. The permanent magnet 130 may be composed of an alloy of neodymium, iron and boron. The round head 132 is configured to be magnetically attracted to the permanent magnet 130. According to the present invention, when the pressure plate 128 and the magnet 130 are tilted relative to the axis of the valve core shaft 125, the magnetic attraction vector generated on the round head 132 of the valve core shaft 125 remains coaxial with the axis of the valve core shaft 125. When the pressure of the control fluid 105 is reduced in the control fluid chamber 122, the attraction vector generated on the round head 132 of the valve core shaft 125 remains coaxial with the axis of the valve core shaft 125 to minimize wear or adhesion in the cylindrical barrel of the sliding valve 100 caused by the tilted orientation of the pressure plate 128.

[0020] In addition, when the pressure of the control fluid 105 increases in the control fluid chamber 122, pushing the surface of the magnet 130 against the surface of the round head 132 of the valve core shaft 125, the force vector generated on the round head 132 of the valve core shaft 125 remains coaxial with the axis of the valve core shaft 125 to minimize wear or adhesion in the cylindrical barrel of the spool valve 100 caused by the tilted orientation of the pressure plate 128. When the pressure of the control fluid 105 increases in the control fluid chamber 122, the composition of the material for the magnet 130 and the composition of the material for the round head 132 can be selected to maximize their hardness and resistance to wear or adhesion caused by their contact surfaces. The profile of the round head 132 can have a hemispherical surface to minimize any component of the force transverse to the axis of the valve core shaft 125 when the surface of the magnet 130 pushes against the surface of the round head 132 of the valve core shaft 125.

[0021] The figure shows the coil spring 140 located in the inner second chamber 124, which maintains the spring force against the pressure plate 128 directed toward the flexible membrane 126. The figure shows the bushing 142 positioned around the valve core shaft 125 to support the valve core shaft in the cylindrical barrel of the housing 102. The figure shows the seals 144 between the bushing 142 and the cylindrical barrel of the housing 102 between the ports Y1, Y2, S, E1 and E2.

[0022] Figure 3 According to an embodiment of the present invention, Figure 2 1 is a side cross-sectional view of a control system of the spool valve 100 , wherein the control fluid pressure signal 105 increases to adjust the valve core shaft 125 of the spool valve 100 to be located at a cross point where the working fluid has equal pressure at the Y1 port and the Y2 port.

[0023] Figure 4 According to an embodiment of the present invention, Figure 3 1 is a side sectional view of the control system of the sliding valve 100, wherein the control fluid pressure signal 105 is further increased to adjust the valve core shaft 125 of the sliding valve 100 to a position where the working fluid at the Y2 output port is at zero pressure and the working fluid at the Y1 output port is at a position where the supply port S pressure is located.

[0024] Figure 5A A pressure plate 128 is shown oriented perpendicular to the shaft axis 127 and a magnetic attraction force vector 134 generated on a rounded end 132 of the valve core shaft 125 remains coaxial with the shaft axis 127 to minimize wear or sticking in the cylindrical barrel of the sliding valve 100 in accordance with an embodiment of the present invention.

[0025] Figure 5BA pressure plate 128 is shown oriented to be tilted upward relative to the shaft axis 127 according to an embodiment of the present invention, and a magnetic attraction vector 134 generated on the round head 132 of the valve core shaft 125 remains coaxial with the shaft axis 127 to minimize wear or sticking in the cylindrical barrel of the sliding valve 100.

[0026] Figure 5C A pressure plate 128 is shown oriented to be tilted downward relative to the shaft axis 127 according to an embodiment of the present invention, and a magnetic attraction vector 134 generated on the round head 132 of the valve core shaft 125 remains coaxial with the shaft axis 127 to minimize wear or sticking in the cylindrical barrel of the sliding valve 100.

[0027] Figure 6 1 is a three-dimensional side cross-sectional view of a control system for a spool valve 100, showing exhaust ports E1 and E2 for the spool valve 100. The figure shows a permanent magnet 130 mounted on a pressure plate 128 in an inner second chamber 124 and a round head 132 formed on the end of a valve core shaft 125, which is configured to be magnetically attracted to the permanent magnet 130.

[0028] Figure 7 is a three-dimensional side view of the spool valve, showing the control fluid pressure signal port 120 , the working fluid ports Y1 and Y2 , the working fluid supply port S, and the working fluid exhaust ports E1 and E2 for the spool valve 100 .

[0029] Although specific example embodiments of the present invention have been disclosed, persons skilled in the art will understand that changes may be made to the details described with respect to the specific example embodiments without departing from the spirit and scope of the present invention.

Claims

1. A slide valve control system, comprising: a housing including a first chamber for receiving a control fluid and a second chamber for supporting a spool shaft having an axis, the spool shaft being configured to move along the axis; a flexible membrane separating the first chamber from the second chamber and configured to form a flexible barrier to a control fluid in the first chamber; a pressure plate in the second chamber against which the flexible membrane is pressed in response to changes in pressure of the control fluid; a permanent magnet mounted on the pressure plate in the second chamber; as well as a round head formed on an end of the valve core shaft and composed of a ferromagnetic material configured to be magnetically attracted to the permanent magnet; The valve core shaft has a boss or full-bore portion facing the interior-facing surface of the cylindrical barrel, the boss or full-bore portion being separated by a narrower portion providing port interconnection through the cylindrical barrel; When the pressure plate and the magnet are tilted relative to the axis of the valve core shaft, the magnetic attraction force vector generated by the permanent magnet on the round head of the valve core shaft remains coaxial with the axis of the shaft.

2. The slide valve control system according to claim 1, wherein: When the pressure of the control fluid is reduced in the first chamber, the attraction force vector generated on the rounded end of the spool shaft remains coaxial with the axis of the shaft.

3. The spool valve control system according to claim 1, wherein: When the pressure of the control fluid increases in the first chamber and pushes the magnet toward the round head of the valve core shaft, the force vector generated on the round head of the valve core shaft remains coaxial with the axis of the valve core shaft.

4. The slide valve control system according to claim 1, wherein: The round head formed on the end of the valve core shaft is composed of an alloy of iron, cobalt or nickel.

5. The spool valve control system according to claim 1, wherein: The permanent magnets are composed of an alloy of neodymium, iron and boron.

6. The spool valve control system according to claim 1, wherein: The composition of the material for the magnet and the composition of the material for the round head maximize their hardness and resistance to wear or adhesion due to their surface contact when the pressure of the control fluid increases in the first chamber.

7. The spool valve control system according to claim 1, wherein: The knob is contoured to have a hemispherical surface to minimize any component of force transverse to the axis of the valve core shaft when the surface of the magnet pushes against the surface of the knob of the valve core shaft.

8. The spool valve control system according to claim 1, wherein: Wear or sticking caused by the angled orientation of the pressure plate, which forces the boss of the valve core shaft to cause wear on the inner facing surface of the cylindrical barrel supporting the valve core shaft in the housing, is minimized.

9. A spool valve control system in a spool valve, the spool valve comprising a flexible membrane separating a control fluid chamber and an inner chamber, and a pressure plate in the inner chamber, the flexible membrane being pressed against the pressure plate in response to a change in the pressure of a control fluid in the control fluid chamber, the spool valve control system comprising: a permanent magnet mounted on a pressure plate in the interior chamber; as well as a round head formed on an end of the valve core shaft in the inner chamber, the round head being composed of a ferromagnetic material and configured to be magnetically attracted to the permanent magnet; Wherein, when the pressure plate and the magnet are tilted relative to the axis of the valve core shaft, the magnetic attraction vector generated by the permanent magnet on the round head of the valve core shaft remains coaxial with the axis of the valve core shaft; Therein, wear or sticking caused by the angled orientation of the pressure plate, which forces the boss of the valve core shaft to cause wear on the inner facing surface of the cylindrical barrel supporting the valve core shaft in the housing, is minimized.

10. The spool valve control system according to claim 9, wherein: When the pressure of the control fluid is reduced in the first chamber, the attraction force vector generated on the rounded end of the spool shaft remains coaxial with the axis of the shaft.

11. The spool valve control system according to claim 9, wherein: When the pressure of the control fluid increases in the first chamber and pushes the magnet toward the round head of the valve core shaft, the force vector generated on the round head of the valve core shaft remains coaxial with the axis of the valve core shaft.

12. The spool valve control system according to claim 9, wherein: The round head formed on the end of the valve core shaft is composed of an alloy of iron, cobalt or nickel.

13. The spool valve control system according to claim 9, wherein: The permanent magnets are composed of an alloy of neodymium, iron and boron.

14. The spool valve control system according to claim 9, wherein:The composition of the material for the magnet and the composition of the material for the round head maximize their hardness and resistance to wear or adhesion due to their surface contact when the pressure of the control fluid increases in the first chamber.

15. The spool valve control system according to claim 9, wherein: The knob is contoured to have a hemispherical surface to minimize any component of force transverse to the axis of the valve core shaft when the surface of the magnet pushes against the surface of the knob of the valve core shaft.

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