Control valve means for fluid motors

Abstract

A pressure reducing valve mechanism maintains pressure in one of the service passages of a control valve at a desirably low value except at times when the control valve element is actuated to a position effecting flow of pressurized supply fluid to said service passage for delivery to a motor governed by the control valve.

The invention is defined by the following claims: .[.1. Valve instrumentalities for governing operation of a fluid motor, characterized by: 
     
        interference from said pressure reducing valve mechanism..]. .[.2.  The combination of claim 1, wherein said last named means comprises a chamber communicated with the pressure fluid supply passage means, and a plunger which is connected with said valve member and which operates in said chamber to be held by pressure of supply fluid therein in a position blocking movement of said valve member toward a passageway restricting position..]. .[.3. In combination with a control valve for a fluid motor, having a valve element movable to a first position to communicate a service passage with supply passage means, and movable to a second position to provide for flow of motor exhaust fluid through the service passage to return passage means, said control valve element being movable through a range of metering positions short of said second position thereof to provide for restricted flow of motor exhaust fluid from the service passage to the return passage means in an amount which increases as the valve element approaches its said second position: A. a pressure reducing valve mechanism having 1. a passageway connecting with the service passage and through which pressure fluid flows both to and from the governed motor,   2. a valve member actuatable in one direction to restrict flow of motor exhaust fluid through said passageway,   3. and a spring to yieldingly urge the valve member toward an inactive position affording substantially free flow of motor exhaust fluid through said passageway;     B. means rendered operative in response to the rise in service passage pressure produced by movement of the control valve element to one of its said exhaust flow metering positions for effecting actuation of the pressure reducing valve member in the flow restricting direction an extent depending upon the magnitude of the pressure present in the service passage;   C. and means rendered operative in response to the pressure of supply fluid flowing to the service passage in said first position of the control valve element, for effecting flow of such supply fluid through said passageway and to the governed motor substantially without interference from the   
     
     
        pressure reducing valve member..]. .[.4.  The combination of claim 3, further characterized by: A. said control valve element being movable to a load holding third position to close off the service passage from the fluid supply and return passage means:   B. and said pressure reducing valve mechanism also being operable to maintain the pressure in the service passage at said low value in said load holding position of the valve element..]. .[.5. The combination of claim 3, wherein said last named means comprises:   A. means connected with the service passage providing a bypass around the pressure reducing valve mechanism, through which pressure fluid can flow to the governed motor in said first position of the valve element;   B. and a check valve in said bypass to block reverse flow of fluid through the bypass..]. .[.6. Valve instrumentalities for governing flow of pressure fluid to and from a fluid motor via a service line connectable therewith, characterized by:   A. a directional control valve having fluid supply and return passage means, a service passage for connection with the service line to form a part thereof, and a valve element movable from a hold position to first and second operating positions to respectively communicate the service passage with the fluid supply and return passage means, said valve element being movable through a range of metering positions to provide for return flow of motor exhaust fluid from the service passage to the return passage means in an amount which increases with movement of the valve element toward said second position thereof and reaches maximum thereat;   B. a pressure reducing valve mechanism having a valve member to regulate flow of motor exhaust fluid through the service line to the service passage, said valve member being urged by a spring toward a normally inactive position but being actuatable out of said position in a direction to restrict return flow of motor exhaust fluid through said service line to the service passage under force exerted on the valve member counter to the force of its spring;   C. means for monitoring the pressure of fluid present in the service passage and rendered operative by the valve element in said metering positions thereof to translate said monitoring pressure into said actuating force on the valve member whenever said monitored pressure rises to a predetermined value above that of fluid in the return passage means;   D. and means rendered operative by supply fluid pressure, in said first operating position of the valve element, for assuring substantially free flow of pressure fluid through the service line to a fluid motor connected therewith..]. .[.7. The valve instrumentalities of claim 6 wherein said last named means comprises:   A. means defining a piston connected with said valve member and which can be held by fluid pressure force in a position blocking movement of the valve member toward its active position;   B. and means for translating pressure of supply fluid into said force on the piston..]. .[.8. The valve instrumentalities of claim 6, wherein said last named means comprises:   A. a passage connecting with the service passage and through which supply fluid can flow in bypass relation to said valve member in said first operation position of the control valve element;   B. and a check valve in said bypass passage to block flow of exhaust fluid therethrough to the return means in said second operating position of the control valve element..]. .[.9. The valve instrumentalities of claim 6, further characterized by:   A. said pressure reducing valve mechanism comprising a pair of chambers, one of which is communicated with said service passage to be pressurized by motor exhaust fluid therein;   B. said valve member having portions disposed in said chambers, and being movable toward an active position restricting said passageway in response to pressure of motor exhaust fluid in said one chamber;   C. and means venting the other of said chambers..]. .[.10. The combination of claim 9, wherein said last named means comprises a vent line at all times connecting said other chamber with pressure fluid supply passage means in the control valve..]. .[.11. The combination of claim 9, wherein said venting means communicates with the pressure fluid supply passage means in the control valve..]. .[.12. The combination of claim 9, wherein said venting means comprises a duct at all times communicated with the fluid return means..]. .[.13. The combination of claim 9, wherein said venting means comprises a duct which communicates with the pressure fluid supply passage means in the control valve and further comprises a passage in the control valve element effective only in the hold position thereof to communicate the pressure fluid supply passage with the fluid return means..]. .[.14. The combination of claim 9, wherein said venting means comprises a duct communicating said other chamber with the pressure fluid supply passage means, and wherein passage means in the control valve element communicates the pressure fluid supply passage means with the return means in the hold position of the valve element..]. .Iadd. 15. Valve instrumentalities for governing flow in a service line connectable with a fluid motor of pressure fluid to the motor and return fluid therefrom, said valve instrumentalities being of the type comprising a directional control valve having a service passage for connection with the service line to form a part thereof, fluid supply passage means, return passage means, and a valve element movable from a hold position blocking communication between the service passage and both of said passage means to a pair of operating positions, in one of which the service passage is communicated with the fluid supply passage means and in the other of which the service passage is communicated with the return passage means, through a range of metering positions at which the valve element restricts flow of fluid between the service passage and a passage means to an extent that decreases with movement of the valve element towards an operating position, said valve instrumentalities comprising:   A. a pressure reducing valve mechanism for said service passage (1) having a single passageway through which all fluid that flows in said service line must pass,   (2) having a valve member movable in one direction to an open position and movable in the opposite direction to a restricting position throttling flow of fluid through said passageway, said valve member being arranged to be urged in said opposite direction with a force that depends upon pressure of fluid in the service passage,     (3) a chamber separate from said passageway, and   (4) means responsive to pressure of fluid in said chamber and operatively associated with the valve member for imposing a biasing force on said valve member that is in said one direction and of a magnitude that depends upon pressure of fluid in said chamber and is sufficient to maintain the valve member in its open position when fluid pressure in the service passage does not exceed pressure of fluid in said chamber; and   B. means at all times communicating said chamber with the fluid supply passage means, so that said valve member is held in its open position whenever pressure fluid is flowing from the pressure fluid source to the motor through the service passage. .Iaddend. .Iadd. 16. The valve instrumentalities of claim 15, further characterized by:   C. means at all times imposing upon said valve member a biasing force in said one direction that is of substantially constant magnitude and is in addition to the biasing force imposed upon said means responsive to pressure of fluid in said chamber, so that movement of the valve member in said opposite direction requires that the biasing force exerted on the valve member by fluid in the service passage exceed the sum of the forces in said one direction. .Iaddend..Iadd. 17. The valve instrumentalities of claim 15, further characterized by:   C. means operative in the hold position of said valve element for communicating the fluid supply passage means with the return passage means, for venting of said chamber when the valve element is moved to its hold position. .Iaddend. .Iadd. 18. The valve instrumentalities of claim 17, further characterized by:   D. said valve element and said valve member being so arranged that in the restricting position of the latter leakage of return fluid thereacross does not exceed leakage of return fluid from the service passage to the return passage means across the valve element in its hold position. .Iaddend..Iadd. 19. The valve instrumentalities of claim 15, wherein there is a second service line connectable with a fluid motor to provide for reversible actuation of the same and the directional control valve has a second service passage for connection with said second service line to form a part thereof, further characterized by:   C. a second pressure reducing valve mechanism for the second service passage, substantially identical to said first mentioned pressure reducing valve mechanism; and   D. means at all times communicating the chamber of the second pressure reducing valve mechanism with the fluid supply passage means, to enable the two pressure reducing valve mechanisms to cooperate for coordination of fluid flows through the respective service lines. .Iaddend. .Iadd. 20. Valve instrumentalities for governing operation of a fluid motor, characterized by:   A. a control valve having a pair of service passages for connection with the opposite sides of a fluid motor, and a valve element movable through a number of metering positions to full flow operating positions concurrently communicating either of the service passages with pressure fluid supply means and the other service passage with fluid return means in the valve, from a hold position closing off said service passages from the fluid supply and return means;   B. a pressure reducing valve mechanism for each service passage, having a passageway through which exhaust fluid from the governed motor flows to the fluid return means through the associated service passage and through which same passageway supply fluid from the pressure fluid supply means must flow to reach the governed motor, each of said pressure reducing valve mechanisms having a chamber separate from said passageway but communicated with the pressure fluid supply means and further having a pressure responsive valve member actuatable in a direction to restrict the passageway to an extent depending upon the pressure of motor exhaust fluid in the associated service passage whenever the pressure of said exhaust fluid exceeds that of fluid at the pressure fluid supply means during times the valve element is in one of said metering positions, to thereby maintain the pressure of exhaust fluid in the associated service passage at a substantially uniformly low value above that of fluid in the return means;   C. and means located in said chamber of each pressure reducing valve mechanism operatively connected with the valve member thereof and rendered operative in response to pressure of supply fluid in said chamber for preventing movement of said valve member in said direction when fluid pressure in the associated service passage does not exceed that of fluid at the pressure fluid supply means, to thus permit flow of supply fluid through the associated service passage to the governed motor substantially without interference from said pressure reducing valve mechanism. .Iaddend. .Iadd. 21. The combination of claim 20, wherein said last named means comprises a plunger which is connected with said valve member and which operates in said chamber to be biased by pressure of supply fluid therein towards a position preventing movement of said valve member in said direction. .Iaddend. .Iadd. 22. Valve instrumentalities for governing flow of pressure fluid to and from a fluid motor via a service line connectable therewith, characterized by:   A. a directional control valve having fluid supply and return passage means, a service passage for connection with the service line to form a part thereof, and a valve element movable from a hold position to first and second operating positions to respectively communicate the service passage with the fluid supply and return passage means, said valve element being movable through a range of metering positions to provide for return flow of motor exhaust fluid from the service passage to the return passage means in an amount which increases with movement of the valve element toward said second position thereof and reaches maximum thereat;   B. a pressure reducing valve having (1) a pair of chambers, and   (2) a valve member to regulate flow of motor exhaust fluid through the service passage, said valve member having opposing portions respectively disposed in said chambers and being urged by a spring in one direction toward a normally inactive position but being movable in the opposite direction toward an active position restricting return flow of motor exhaust fluid through said service line to the service passage;     C. monitoring means rendered operative by the valve element in said metering positions thereof to translate pressure of fluid present in the service passage into a force on the valve member that moves it in said opposite direction whenever pressure of fluid in said service passage exceeds that of fluid in the return passage means by more than a predetermined difference, said monitoring means comprising means communicating one of said chambers with said service passage; and   D. communication means comprising duct means by which the other of said chambers is at all times communicated with the fluid supply passage means in the control valve, said communication means being rendered effective to vent said other chamber in consequence of the valve element of the directional control valve being in its hold position, and being rendered operative by fluid pressure in the supply passage means when the valve element is in its first operating position to pressurize said other chamber and thus maintain the valve member in its inactive position at which said valve member allows substantially free flow of pressure fluid through the service line to a motor connected therewith. .Iaddend. .Iadd. 23. The valve instrumentalities of claim 22 wherein said communication means further comprises a passage in the control valve element effective only in the hold position thereof to communicate the fluid supply passage means with the return fluid passage means. .Iaddend. .Iadd. 24. Valve instrumentalities for governing flow of pressure fluid to and from a fluid motor via a service line connectable therewith, characterized by:   A. a directional control valve having fluid supply and return passage means, a service passage for connection with the service line to form a part thereof, and a valve element movable from a hold position to first and second operating positions to respectively communicate the service passage with the fluid supply and return passage means, said valve element being movable through a range of metering positions to provide for return flow of motor exhaust fluid from the service passage to the return passage means in an amount which increases the movement of the valve element toward said second position thereof and reaches maximum thereat;   B. a pressure reducing valve having (1) a pair of chambers, and   (2) a valve member to regulate flow of motor exhaust fluid through the service passage, said valve member having opposite portions respectively disposed in said chambers and being urged by a spring in one direction toward a normally inactive position but being movable in the opposite direction toward an active position restricting return flow of motor exhaust fluid through said service line to the service passage;     C. monitoring means rendered operative by the valve element in said metering positions thereof to translate pressure of fluid present in the service passage into a force on the valve member that moves it in said opposite direction whenever pressure of fluid in said service passage exceeds that of fluid in the return passage means by more than a predetermined difference, said monitoring means comprising means communicating one of said chambers with said service passage;   D. communication means at all times communicating the other of said chambers with the fluid supply passage means in the control valve, to pressurize said other chamber from fluid pressure in the supply passage means when the valve element is in its first operating position and thus maintain the valve member in its inactive position at which said valve member allows substantially free flow of pressure fluid through the service line to a motor connected therewith; and   E. duct means rendered operative to vent said other chamber in consequence of the valve element of the directional control valve being in its hold position. .Iaddend..Iadd. 25. The valve instrumentalities of claim 24 wherein said duct means comprises a passage in the control valve element effective only in the hold position thereof to communicate the fluid supply passage means with the return fluid passage means. .Iaddend.