Patent ID: 12234842

It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of this disclosure or which render other details difficult to perceive may have been omitted. It should be understood that this disclosure is not limited to the particular embodiments illustrated herein.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of a pressure control valve constructed in accordance with principles of the present disclosure include means for reducing a pilot flow between a supply port and a tank port thereof when the pressure control valve is in a neutral position. Embodiments of a pressure control valve constructed in accordance with principles of the present disclosure comprise a pilot-operated proportional pressure control valve in the form of a hydraulic cartridge valve that includes means for reducing a pilot flow between a supply port and a tank port in which the pilot flow reducing means comprise a pilot flow control assembly in a pilot stage to significantly reduce the pilot flow between the supply port and the tank port when the valve is in a neutral position. In embodiments, a hydraulic cartridge valve comprises a pilot flow control assembly including a first control element and a second control element that define, when the spool is in the neutral position, a restricted pilot flow path along a pilot flow passage including a first orifice and a second orifice in serial relationship with each other. In embodiments, the second orifice has a cross-sectional area equal to or less than the cross-sectional area of the first orifice.

Embodiments of a pressure control valve constructed according to principles of the present disclosure can comprise a two-stage valve including a main stage and a pilot stage adapted to use pilot flow to control a main stage spool. The pilot flow is controlled by limiting the flow of oil through a pair of small orifices in series relationship with each other. The leakage control element is configured to be self-cleaning. When the coil is energized, the spool will move away from the pilot pin and flush out any contaminate that is trapped in the spool or orifice passages to the tank port.

Embodiments of a pressure control valve constructed according to principles of the present disclosure can have a wide variety of different forms, as will be appreciated by one skilled in the art. For example, in embodiments, a pressure control valve constructed according to principles of the present disclosure can be, for example, in the form of a pilot-operated proportional pressure control cartridge valve. In other embodiments, a hydraulic valve constructed according to principles of the present disclosure can comprise a pilot flow control assembly applied to other hydraulic valves that utilize pilot flow to control the main stage spool.

Embodiments of a hydraulic control system constructed in accordance with principles of the present disclosure can selectively operate an actuator (e.g., cylinder) using an embodiment of a pressure control valve constructed in accordance with principles of the present disclosure. Embodiments of a pressure control valve constructed in accordance with principles of the present disclosure can be used to control the pressure inside an actuator. The control pressure is proportional to the amount of current applied to the coil of the pressure control valve. The current can be variably adjusted across a prescribed range using a variable electric input.

Turning now to the Figures, there is shown inFIG.1an embodiment of a hydraulic cartridge pressure control valve25constructed according to principles of the present disclosure. The illustrated valve comprises a pilot-operated proportional pressure control valve that includes a main stage27and a pilot stage28. The illustrated pressure control valve includes a body30, a spool31, a biasing element32in the form of a spring, a pilot flow valve assembly34, and means for restricting pilot flow through the pilot flow passage in the form of a pilot flow control assembly35.

In embodiments, the body30can have any configuration suitable for the intended application(s) of the pressure control valve25. In embodiments, the body30can be made from a plurality of components that are assembled together to define an axial bore43and a plurality of ports in communication with the axial bore43. In embodiments, the body30can be configured to facilitate the installation of the pressure control valve25in a hydraulic body, manifold or other suitable component.

In the illustrated embodiment, the body30includes a frame38and a cage40. In embodiments, the frame38and the cage40can be made using any suitable technique as will be appreciated by one skilled in the art. For example, in embodiments, the frame38can comprise a cold-forged frame that is machined to its final shape. The lower portion of the frame38interfaces with the cage40and is assembled by forming the end of the frame38over the cage40. In embodiments, the cage40can be mounted to the frame38using any suitable technique, such as by being threadedly engaged therewith as shown inFIG.1.

The frame38includes a circular flange41configured to secure the valve25within a valve cavity by use of a mounting plate (not shown). In other embodiments, the body30can include an external threaded surface that is adapted to be threadedly engaged with a body, manifold, or other suitable component to allow the pressure control valve25to be used in a hydraulic circuit.

In the illustrated embodiment, the main stage27of the pressure control valve25comprises the cage40, the spool31, and the biasing member32. The cage40is hollow and is configured to be inserted into a cavity formed in a suitable housing such that the valve25is in fluid communication with a hydraulic circuit within which the valve25is intended to be used.

The cage40of the body30defines the axial bore43, a supply port2, a work port3, and a tank port4. Each of the supply port2, the work port3, and the tank port4are in fluid communication with the axial bore43. The cage40defines three rows of cross-holes45,46,47in communication with the axial bore43with the cross-holes45,46,47of each row being disposed in spaced relationship to each other around the radial circumference of the cage40and respectively defining the supply port2, the work port3, and the tank port4. It should be understood that the names used herein for the ports2-4defined by the cage40are used for convenient reference only and should not be construed to limit the operation of the ports2-4or the nature of the fluid flow (in either direction) through the ports2-4of the cage40.

The spool31is disposed within the axial bore43of the body30and is axially movable over a range of travel between a neutral position, as shown inFIG.1, and a shifted position, as shown inFIG.6. When the spool31is in the neutral position, the spool31prevents fluid flow between the supply port2and the work port3such that the supply port2and the work port3are in fluid isolation from each other and permits fluid flow between the work port3and the tank port4such that the work port3and the tank port4are in fluid communication with each other. When the spool31is in the shifted position, the spool31permits fluid flow between the supply port2and the work port3such that the supply port2and the work port3are in fluid communication with each other and prevents fluid flow between the work port3and the tank port4such that the work port3and the tank port4are in fluid isolation from each other. In embodiments, the pressure control valve25is configured such that the spool31has a range of travel including at least one intermediate position between the neutral position and the shifted position in which the work port3is in fluid communication with both the tank port4and the supply port2.

Referring toFIGS.1and2, in embodiments, at least one of the spool31and the body30define a pilot flow passage50in fluid communication with the supply port2and the tank port4when the spool31is in the neutral position. In the illustrated embodiment, the spool31and the body30cooperate together to define the pilot flow passage50. The illustrative pilot flow passage50of the pressure control valve25is indicated by the arrows found inFIGS.1and2. In embodiments, the pilot flow passage50is in communication with the supply port2and the tank port4over the entire range of travel of the spool31. In embodiments, the degree to which the pilot flow passage50is restricted can vary as a function of the position of the spool31over the range of travel between the neutral position and the shifted position.

For example, in the illustrated embodiment, the spool31defines a counterbore opening52which leads to the pilot flow passage50. As the spool31moves from the intermediate position shown inFIG.5to the shifted position shown inFIG.6, the counterbore opening52to the pilot flow passage50closes so that the pilot flow passage50becomes more and more restricted.

Referring toFIG.1, the spool31includes a supply land54at a first end55having a supply groove57defined therein and a tank land58at a second end59. A work groove64is defined between the supply land54and the tank land58. The spool31defines a pilot flow passage portion65that extends between the supply groove and the open second end59of the spool31. The spool31defines a damping flow passage67having a damping orifice69therein and extending between the work groove64and the open first end55of the spool31.

The supply land54is configured to block the row of metering cross holes45comprising the supply port2from being in fluid communication with the work port3when the spool31is in the neutral position and to permit fluid flow therebetween when the spool31is in the shifted position (seeFIG.6). The supply groove57is configured to fluidly connect the supply port2and the pilot flow passage50when the spool31is in the neutral position but not when the spool31is in the shifted position (seeFIG.6). The supply land54is configured to block the row of metering cross holes45comprising the supply port2from being in fluid communication with pilot flow passage50when the spool31is in the shifted position (seeFIG.6).

The work groove64is configured to fluidly connect the work port3and the tank port4when the spool31is in the neutral position but not when the spool31is in the shifted position (seeFIG.6). Rather, the work groove64is configured to fluidly connect the work port3and the supply port2when the spool31is in the shifted position (seeFIG.6).

The tank land58is configured to permit fluid flow between the respective rows of metering cross holes47,46comprising the tank port4and the work port3when the spool31is in the neutral position. The tank land is configured to prevent the tank port4from being in fluid communication with the work port3and to prevent the pilot flow passage50from being in fluid communication with the tank port4when the spool31is in the shifted position (seeFIG.6).

Referring toFIG.1, in the illustrated embodiment, a plug71is disposed within the axial bore43of the body30and is secured to the cage40at a distal end72of the cage40to occlude the axial bore43, thereby occluding an axial port1of the body30. The plug71is secured to the cage40by a retaining ring74. The plug71and the spool31cooperate with the cage40of the body30to define a spring chamber75within the axial bore43. The work port3and the spring chamber75are in fluid communication with each other via the damping flow passage67of the spool31over the range of travel of the spool31between the neutral position and the shifted position (seeFIG.6).

In the illustrated embodiment, the biasing element32comprises a spring. In other embodiments, any other structure and/or technique for biasing the spool31to the neutral position can be used. The spring32is operatively arranged with the spool31to bias the spool31to the neutral position, as shown inFIG.1. The spring32is disposed within the spring chamber75such that opposing ends of the spring32respectively act against the plug71and the spool31.

The spring32provides a bias force to put the spool31in the neutral position when the coil105is de-energized, thereby blocking the supply port2from the work port3. This type of spool design is known as “closed-in-transition” or “positive overlap.” In embodiments, the closed-in-transition spool configuration is used in pressure reducing/relieving valve applications to help maintain the stability of the valve (reducing/inhibiting pressure oscillations during operation). In the illustrated embodiment, damping of the valve25is accomplished by controlling the flow of hydraulic fluid in and out of the spring chamber75via the damping orifice69.

A plurality of seal members81-85provided to help provide a sealing arrangement within the valve25and between the valve body and the structure to or into which the pressure control valve25is mounted. The seal members81-83provide sealing between the ports2-4and prevent external leakage. The seal members84,85provide internal sealing within the valve25. In embodiments, the seal members81-85can have any suitable form and construction, such as suitable O-ring seals, and can be provided in any suitable number to provide hydraulic isolation and/or seals to inhibit leakage, as appropriate and as will be understood by one skilled in the art.

The pilot stage28of the pressure control valve25comprises the pilot flow valve assembly34and the pilot flow control assembly35. The pilot flow valve assembly34is configured to selectively occlude the pilot flow passage50. In the illustrated embodiment, the pilot flow valve assembly34is configured to selectively prevent pilot flow from the pilot flow passage50out the tank port4.

Referring toFIG.2, in embodiments, the pilot flow valve assembly34includes a closure element90, a seat91, a push pin92, and an actuator93(seeFIG.1). The closure element90is movable between an open position (as shown inFIG.2) and a closed position (as shown inFIGS.5and6). When the closure element90is in the open position, the pilot flow passage50is open. When the closure element90is in the closed position, the pilot flow passage50is occluded. In the illustrated embodiment, the closure element90of the pilot flow valve assembly34comprises a spherical ball.

Referring toFIG.2, in the illustrated embodiment, the seat91is secured to the cage40of the body30by being threadedly engaged therewith. The seat91includes a first end96and a second end97. The seat91defines a through passage98that comprises a portion of the pilot flow passage50and that extends from the first end96to the second end97of the seat91. The ball90is adjacent the first end96of the seat91. In embodiments, one of a pair of control elements101,102of the means for restricting pilot flow is secured to the seat91adjacent the second end97thereof.

In the illustrated embodiment, the push pin92is arranged with the ball90. The push pin92is axially movable in order to selectively place the ball90in sealing engagement with the seat91.

Referring toFIG.1, in embodiments, the actuator93is configured to selectively move the closure element90of the pilot flow valve assembly34to the closed position. In embodiments, the actuator93can be any suitable mechanism configured to selectively move the closure element90of the pilot flow valve assembly34to the closed position. In the illustrated embodiment, the actuator93is mounted to the body30. In the illustrated embodiment, the actuator93is arranged with the push pin92and is configured to selectively move the push pin92to thereby seat the ball90against the seat91to occlude the through passage98of the seat91and thereby occlude the pilot flow passage50.

In the illustrated embodiment, the actuator93comprises a solenoid assembly104including a coil105, an armature107, and a pole piece108. The coil105is mounted to the frame38of the body30and is disposed around the armature107. The coil105can be mounted to the frame38using any suitable technique as will be familiar to one skilled in the art. In embodiments, the coil105is operably arranged with a source of electrical current (not shown) via an electrical connector109such that a controller (not shown) can selectively actuate the coil105by applying electrical current thereto.

The armature107is associated with the coil105such that operation of the actuator93by a controller can selectively move the armature107. The armature107is disposed within the axial bore43of the body30and is configured to move toward the pole piece108in response to an electrical current being applied to the coil105. The armature107is arranged with the push pin92such that the movement of the armature107toward the pole piece108moves the push pin92to thereby move the ball90to the closed position and into sealing arrangement with the seat91. In embodiments, the solenoid assembly104is configured such that, when coil105is energized, the push pin92moves the ball90in an amount proportional to the electrical current applied to the coil105.

In the illustrated embodiment, the pole piece108is part of the frame38and is configured to limit the movement of the armature107to a predetermined range of axial travel. In embodiments, the solenoid assembly104has a proportional characteristic where the magnetic attractive force between the frame38and the armature107is proportional to the current applied to the coil105. The solenoid force therefore remains constant over the stroke. In embodiments, a non-magnetic spacer can be arranged with the armature107to help prevent the armature107from latching to the polepiece108.

Referring toFIG.2, in embodiments, the means for restricting pilot flow define a restriction115along the pilot flow passage50. The restriction115is configured to restrict the flow of hydraulic fluid through the pilot flow passage50in a variable manner as a function of the position of the spool31. In the illustrated embodiment, the restriction115is in the form of an orifice.

In embodiments, the means for restricting pilot flow define, when the spool31is in the neutral position, a restriction in the form of an orifice115in serial relationship with at least one other orifice117disposed along the pilot flow passage50. In embodiments, the orifice115defined by the means for restricting pilot flow has a cross-sectional area equal to or less than the cross-sectional area of at least one other orifice117disposed along the pilot flow passage50when the spool31is in the neutral position, as shown inFIG.2. In embodiments, the size of the orifice115defined by the means for restricting pilot flow is variable as a function of the position of the spool31.

Referring toFIG.2, in the illustrated embodiment, the means for restricting pilot flow include the pilot flow control assembly35. In embodiments, the pilot flow control assembly35is disposed in the pilot flow passage50. In the illustrated embodiment, the pilot flow control assembly35includes the first control element101and the second control element102. The leakage control elements101,102are used to control the pilot flow leakage. The first control element101is secured to the spool31, and the second control element102is secured to the body30such that the first control element101is movable with respect to the second control element102upon axial movement of the spool31relative to the body30. The first control element101and the second control element102define, when the spool31is in the neutral position, a restricted pilot flow path50′ along the pilot flow passage50including the first orifice117and the second orifice115in serial relationship with each other. The second orifice115has a cross-sectional area equal to or less than the cross-sectional area of the first orifice117. In the illustrated embodiment, the first control element101comprises a restriction member, and the second control element102comprises a pilot pin.

In embodiments, the leakage control elements101,102are configured to significantly reduce the pilot flow with supply pressure applied with no current applied to the coil105. In the illustrated embodiment, the leakage control elements101,102incorporate an offset feature118(see alsoFIGS.3and4) in the first control element101which is in the form of the restriction member, or orifice spacer, along with the second control element102in the form of the pilot pin that protrudes into the opening140of the orifice spacer. The interrelationship between the pilot pin102and the offset opening118of the restriction member101defines the second orifice115which comprises a very small open area through which hydraulic fluid can pass, thereby reducing the pilot flow.

Referring toFIG.2, in the illustrated embodiment, the restriction member101is installed in the spool31via a spring ring120. The restriction member101defines a through passage122comprising a portion of the restricted pilot flow path50′ including the orifice117. The orifice117in the restriction member101is fixed in that the size of the orifice117is constant over the range of travel of the spool31and the restriction member101. The restriction member101is disposed in the pilot flow passage50such that the pilot flow through the pilot flow passage50is directed through the fixed orifice117in the portion of the restricted pilot flow path50′ defined by the restriction member101.

In embodiments, the pilot flow passage50can omit the fixed orifice117such that the pilot flow passage50includes only the variable orifice115of the means for restricting pilot flow. In embodiments, the pilot flow passage50can include one or more fixed orifices disposed along the pilot flow passage50and each in serial relationship with the variable orifice115of the means for restricting pilot flow.

The restriction member101is configured to control flow of hydraulic fluid into the pilot stage28. The size of the first orifice117controls the pilot flow leakage.

In the illustrated embodiment, the pilot pin102is secured to the seat91with a retaining ring130. In embodiments, the pilot pin102and the seat91can be combined into one part, thereby eliminating the need for the retaining ring130. The pilot pin102includes a base132and a pin portion134. The base is generally disc-shaped and defines a pair of passages135,136therethrough in order to all pilot flow therethrough. The pin portion134of the pilot pin102has a conical distal end138which is arranged with an opening140of the through passage122of the restriction member101to define the second orifice115when the spool31is in the neutral position. The conical distal end138of the pilot pin102extends into the through passage122of the restriction member101.

In the illustrated embodiment, when the spool31is in the neutral position, the first control element101and the second control element102are in a first position with respect to each other and cooperate together to define the second orifice115therebetween. When the spool31is in the shifted position (seeFIG.6), the first control element101and the second control element102are in a second position with respect to each other that is different from the first position such that a clearance141is defined therebetween that is different from the second orifice115in at least one of shape and size such that the restricted pilot flow path50′ does not include the second orifice115when the spool31is in the shifted position.

Referring toFIG.1, the spring32under the spool31is configured to keep the restriction member101seated against the pilot pin102in the neutral position. In embodiments, the pre-load force from the spring32is slightly greater than the force due to the inlet pressure acting over the restriction member101center hole diameter. In embodiments of the present disclosure, a small amount of pilot flow through the second orifice115is provided to prevent pressure from building in the pilot stage28that is greater than the spring force of the spring32, which would cause the spool31to self-shift out of the neutral position.

Referring toFIG.1, the illustrated embodiment of the pressure control valve25is shown with the spool31in the neutral position. When the spool31is in the neutral position, the supply land54of the spool31prevents fluid flow between the supply port2and the work port3. The supply groove57permits fluid flow between the supply port2and the tank port4via the pilot flow passage50. The work groove64permits fluid flow between the work port3and the spring chamber via the damping flow passage67. The work groove64permits fluid flow between the work port3and the tank port4.

Referring toFIG.5, the illustrated embodiment of the pressure control valve25is shown with the spool31in an intermediate position between the neutral position and the shifted position. When the spool31is in the illustrated intermediate position, the supply land54of the spool31prevents fluid flow between the supply port2and the work port3. The supply groove57permits fluid flow between the supply port2and the pilot chamber143defined between the first and second control elements101,102via the pilot flow passage50. The work groove64permits fluid flow between the work port3and the spring chamber75via the damping flow passage67. The tank land58of the spool31prevents fluid flow between the work port3and the tank port4.

Referring toFIG.6, the illustrated embodiment of the pressure control valve25is shown with the spool31in the shifted position. When the spool31is in the shifted position, the supply land54of the spool31prevents fluid flow between the supply port2and the work port3and prevents fluid flow between the supply port2and the pilot chamber143via the pilot flow passage50. The work groove64permits fluid flow between the supply port2and the work port3and between the work port3and the spring chamber75via the damping flow passage67. The tank land58of the spool31prevents fluid flow between the work port3and the tank port4.

Referring toFIG.1, when the coil105is de-energized, the spool31of the embodiment of the valve25depicted inFIG.1allows bidirectional flow between the work port3and the tank port4while blocking hydraulic fluid flow from the supply port2to the work port3. In this mode of the pressure control valve25, the supply port2is connected to the tank port4, which is known as “pilot flow” or leakage. Embodiments of a pressure control valve constructed according to principles of the present disclosure can operate to reduce the pilot flow by more than half, and by up to about 90% in other embodiments, of the pilot flow that would otherwise be present in the absence of means for reducing pilot flow constructed according to principles of the present disclosure, including the leakage control elements discussed herein.

Referring toFIG.5, when the coil105is energized, the armature107becomes attracted to the frame38and pushes, via the push pin92, the ball90against the seat91which blocks the flow of hydraulic fluid through the pilot flow passage50. The pilot chamber143, the area between the seat91and the spool31, fills with hydraulic fluid and pressurizes the spool end55at the spring chamber75, thereby causing the spool31to move down and compress the spring32.

Referring toFIG.6, once sufficient current is applied to the coil105, the spool31will compress the spring32below the spool31to the point where the spool31is in the shifted position, as shown inFIG.6, and connects the supply port2to the work port3. When the coil105is energized such that the supply port2is connected to the work port3, pressure at the work port3is controlled proportionally to the amount of current applied to the coil105. If the pressure at the work port3exceeds the setting controlled by the coil105, the pressure is relieved to the tank port4.

In the illustrated embodiment, the leakage control elements101,102are configured to be self-cleaning. When the coil105is energized, the spool31will move away from the pilot pin102and flush out any contamination that is trapped in the spool31or orifice passages to the tank port4.

Embodiments of a pressure control valve constructed in accordance with principles of the present disclosure can provide a reduction in pilot flow leakage relative to a pressure control valve that does not include means for reducing pilot flow following principles of the present disclosure. Embodiments of a pressure control valve constructed in accordance with principles of the present disclosure can include leakage control elements that reduce or eliminate the need for a secondary valve which reduces overall cost of the hydraulic control circuit. Embodiments of a pressure control valve constructed in accordance with principles of the present disclosure can provide desired performance characteristics that are primarily unaffected by the reduction in the de-energized pilot flow provided by the means for reducing pilot flow following principles of the present disclosure.

Referring toFIGS.7-15, other embodiment of means for restricting pilot flow constructed in accordance with principles of the present disclosure are depicted therein. In particular, embodiments of first and second leakage control elements constructed according to principles of the present disclosure and comprising means for restricting pilot flow are shown inFIGS.7-15. It should be understood that the means for restricting pilot flow can be carried out in other equivalent ways which will be appreciated by one skilled in the art.

Referring toFIG.7, an embodiment of means for restricting pilot flow comprising first and second leakage control elements201,202are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In the illustrated embodiment, the first leakage control element201comprises a restriction member, and the second control element202comprises a pilot pin. The restriction member201defines a through passage222having an opening240that includes an offset hole218. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage222of the restriction member201comprises a portion of the restricted pilot flow path250′ including the first orifice (not shown).

The pilot pin202includes a conical distal end238. The conical distal end238of the pilot pin202projects into the portion of the restricted pilot flow path250′ defined by the restriction member201and cooperates with the offset hole218to define the second orifice215when the spool is in the neutral position. When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements201,202can move axially with respect to each other such that the conical distal end238of the pilot pin202is axially displaced relative to the offset hole218of the restriction member201to effectively remove the second orifice215from the pilot flow path. The restriction member201and the pilot pin202ofFIG.7can be respectively similar in construction and function to the restriction member101and the pilot pin102ofFIG.1in other respects.

Referring toFIG.8, an embodiment of means for restricting pilot flow comprising first and second leakage control elements301,302are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In the illustrated embodiment, the first leakage control element301comprises a restriction member, and the second control element302comprises a pilot pin. The restriction member301defines a through passage322having an opening340that includes a counterbore344with a diameter greater than that of the through passage322. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage322of the restriction member301comprises a portion of the restricted pilot flow path350′ including the first orifice (not shown).

The pilot pin302includes a cylindrical distal end339. The cylindrical distal end339of the pilot pin302extends through the counterbore344into the through passage322of the restriction member301and cooperates therewith to define the second orifice315when the spool is in the neutral position. When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements301,302can move axially with respect to each other such that the cylindrical distal end339of the pilot pin302is axially displaced relative to the counterbore344of the restriction member301to effectively remove the second orifice315from the pilot flow path. The restriction member301and the pilot pin302ofFIG.8can be respectively similar in construction and function to the restriction member101and the pilot pin102ofFIG.1in other respects.

Referring toFIG.9, an embodiment of means for restricting pilot flow comprising first and second leakage control elements401,402are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In the illustrated embodiment, the first leakage control element401comprises a restriction member, and the second control element402comprises a pilot pin. The restriction member401defines a through passage422having an opening440that includes a counterbore444with a diameter greater than that of the through passage422. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage422of the restriction member401comprises a portion of the restricted pilot flow path450′ including the first orifice (not shown).

The pilot pin402includes a conical distal end438that defines an intermediate notch445. The conical distal end438of the pilot pin402projects into the portion of the restricted pilot flow path450′ defined by the counterbore444of the restriction member401such that the intermediate notch445of the pilot pin402cooperates with the opening440of the restriction member401to define the second orifice415when the spool is in the neutral position. When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements401,402can move axially with respect to each other such that the conical distal end438of the pilot pin402is axially displaced relative to the opening440of the restriction member401such that the notch445of the pilot pin402is no longer in close proximity to the counterbore444of the restriction member401, thereby effectively removing the second orifice415from the pilot flow path. The restriction member401and the pilot pin402ofFIG.9can be respectively similar in construction and function to the restriction member101and the pilot pin402ofFIG.1in other respects.

Referring toFIG.10, an embodiment of means for restricting pilot flow comprising first and second leakage control elements501,502are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In embodiments, one of the first control element and the second control element comprises a spherical surface, and the other of the first control element and the second control element comprises a restriction member. In the illustrated embodiment, the first leakage control element501comprises a restriction member, and the second control element502comprises a ball having a spherical exterior surface. The restriction member501defines a through passage522having an opening540that includes an offset hole518. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage522of the restriction member501comprises a portion of the restricted pilot flow path550′ including the first orifice (not shown).

The spherical exterior surface of the ball502is arranged with the opening540of the through passage522of the restriction member501and cooperates with the offset hole518to define the second orifice515when the spool is in the neutral position. When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements501,502can move axially with respect to each other such that the ball502is axially displaced relative to the opening540of the restriction member501such that spherical exterior surface of the ball502is no longer in close proximity to the offset hole518of the restriction member501, thereby effectively removing the second orifice515from the pilot flow path. The restriction member501ofFIG.10can be similar in construction and function to the restriction member101ofFIG.1in other respects.

Referring toFIG.11, an embodiment of means for restricting pilot flow comprising first and second leakage control elements601,602are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In the illustrated embodiment, the first leakage control element601comprises a restriction member, and the second control element602comprises a pilot pin. The restriction member601defines a through passage622having an opening640. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage622of the restriction member601comprises a portion of the restricted pilot flow path650′ including the first orifice (not shown).

The pilot pin602includes a tapered distal end637. The tapered distal end637of the pilot pin602extends into the through passage622of the restriction member601and cooperates therewith to define the second orifice615when the spool is in the neutral position. When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements601,602can move axially with respect to each other such that the tapered distal end637of the pilot pin602is axially displaced relative to the opening640of the restriction member601such that the second orifice615is effectively removed from the pilot flow path. The restriction member601and the pilot pin602ofFIG.11can be respectively similar in construction and function to the restriction member101and the pilot pin102ofFIG.1in other respects.

Referring toFIGS.12and13, an embodiment of means for restricting pilot flow comprising first and second leakage control elements701,702are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In the illustrated embodiment, the first leakage control element701comprises a restriction member, and the second control element702comprises a pilot pin.

Referring toFIG.12, the restriction member701defines a through passage722having an opening740that includes a tapered countersink surface747circumscribing the opening740. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage722of the restriction member701comprises a portion of the restricted pilot flow path750′ including the first orifice (not shown).

The pilot pin702includes a base732defining a groove733and a cylindrical distal end739projecting from the base732. The cylindrical distal end739of the pilot pin702extends through the opening740of the restriction member701into the through passage722of the restriction member701when the spool is in the neutral position. The groove733of the pilot pin702cooperates with the tapered countersink surface747of the restriction member701to define the second orifice715when the spool is in the neutral position (see also,FIG.13). When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements701,702can move axially with respect to each other such that the cylindrical distal end739of the pilot pin702is axially displaced relative to the opening740of the restriction member701such that the groove733of the pilot pin702is no longer in close proximity to the tapered countersink surface747of the restriction member701, thereby effectively removing the second orifice715from the pilot flow path. The restriction member701and the pilot pin702ofFIGS.12and13can be respectively similar in construction and function to the restriction member101and the pilot pin102ofFIG.1in other respects.

Referring toFIG.14, an embodiment of means for restricting pilot flow comprising first and second leakage control elements801,802are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In the illustrated embodiment, the first leakage control element801comprises a restriction member, and the second control element802comprises a pilot pin. The restriction member801defines a through passage822having an opening840that includes a tapered countersink surface847circumscribing the opening840. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage822of the restriction member801comprises a portion of the restricted pilot flow path850′ including the first orifice (not shown).

The pilot pin802includes a base832comprising a porous material and a cylindrical distal end839projecting from the base832. The cylindrical distal end839of the pilot pin802extends through the opening840of the restriction member801into the through passage822of the restriction member801when the spool is in the neutral position. The base832of the pilot pin802cooperates with the tapered countersink surface847of the restriction member801to define effectively the second orifice815through the base832when the spool is in the neutral position. In embodiments, the porosity of the base832can be adapted to provide an effective orifice815through the base832according to the intended application of the pressure control valve and the desired flow rate through the effective second orifice815. When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements801,802can move axially with respect to each other such that the cylindrical distal end839of the pilot pin802is axially displaced relative to the opening840of the restriction member801such that the base832of the pilot pin802is no longer in close proximity to the tapered countersink surface847of the restriction member801, thereby effectively removing the second orifice815from the pilot flow path. The restriction member801and the pilot pin802ofFIG.14can be respectively similar in construction and function to the restriction member101and the pilot pin102ofFIG.1in other respects.

Referring toFIG.15, an embodiment of means for restricting pilot flow comprising first and second leakage control elements901,902are shown which are suitable for use in a pressure control valve constructed according to principles of the present disclosure. In the illustrated embodiment, the first leakage control element901comprises a restriction member, and the second control element902comprises a pilot pin. The restriction member901defines a through passage922having an opening940that includes a textured mating surface948and a tapered countersink surface847circumscribing the opening940. When installed in a pressure control valve constructed according to principles of the present disclosure, the through passage922of the restriction member901comprises a portion of the restricted pilot flow path950′ including the first orifice (not shown).

The pilot pin902includes a base932having a textured mating surface933and a cylindrical distal end939projecting from the base932. The cylindrical distal end939of the pilot pin902extends through the opening940into the through passage922of the restriction member901and the textured mating surface933of the pilot pin902cooperates with the textured mating surface948of the restriction member901to define the second orifice915when the spool is in the neutral position. The variation in surface features provided by the textured mating surfaces933,948can provide an effective second orifice915through which the hydraulic fluid can flow in a restricted manner. In embodiments, the textured surfaces933,948can be varied and configured to provide a desired flow rate for the effective second orifice915based upon the intended application of the pressure control valve. When the spool is moved from the neutral position to the shifted position, the first and second leakage control elements901,902can move axially with respect to each other such that the textured mating surface933of the pilot pin902is no longer in close proximity to the textured mating surface948and the tapered countersink surface947of the restriction member901, thereby effectively removing the second orifice915from the pilot flow path. The restriction member901and the pilot pin902ofFIG.15can be respectively similar in construction and function to the restriction member101and the pilot pin102ofFIG.1in other respects.

Referring toFIGS.16and17, another embodiment of a hydraulic cartridge valve1025constructed in accordance with principles of the present disclosure is shown. The hydraulic cartridge valve1025is illustrated in a neutral position. Referring toFIG.16, the illustrated valve1025comprises a pilot-operated proportional pressure control valve that includes a main stage1027and a pilot stage1028. The illustrated pressure control valve1025includes a body1030, a spool1031, a biasing element1032in the form of a spring, a pilot flow valve assembly1034, and means for restricting pilot flow through the pilot flow passage in the form of a pilot flow control assembly1035.

In the illustrated embodiment, the main stage1027of the pressure control valve1025comprises the cage1040of the body1030, the spool1031, and the biasing member1032. The cage1040is hollow and is configured to be inserted into a cavity formed in a suitable housing such that the valve1025is in fluid communication with a hydraulic circuit within which the valve is intended to be used.

The pilot stage1028of the pressure control valve1025comprises the pilot flow valve assembly1034and the pilot flow control assembly1035. The pilot flow valve assembly1034is configured to selectively occlude the pilot flow passage1050defined by the body30. In the illustrated embodiment, the pilot flow valve assembly1034is configured to selectively prevent pilot flow from the pilot flow passage1050out the tank port4.

Referring toFIGS.16and17, the pilot flow control assembly1035includes the body1030, the spool1031, and a control element1102mounted to the body1030. The body1030includes an interior bore surface1048. The body1030defines the pilot flow passage1050and a pilot cross bore1051in fluid communication with the pilot flow passage1050(seeFIG.17). The pilot cross bore1051is open to the interior bore surface1048.

Referring toFIG.17, the spool1031includes a pilot land1053. The pilot land1053of the spool1031and the interior bore surface1048of the body1030define the restriction1015with the diameter of the pilot land being smaller than the diameter of the interior bore surface1048to define the restriction1015therebetween. The pilot land1053is disposed axially between the pilot cross bore1051and the control element1102when the spool1031is in the neutral position, as shown inFIGS.16and17. The pilot cross bore1051is disposed axially between the pilot land1053and the first control element1102when the spool1031is in the shifted position, that is, the pilot land1053moves below the pilot cross bore1051to effectively remove the restriction1015from the pilot flow passage1050when the spool1031is in the shifted position such that the restriction1015is no longer part of the pilot flow passage1050.

The spool1031includes an exterior surface1060. The exterior surface1060of the spool1031defines an exterior groove1061. The exterior groove1061of the spool1031is in axial alignment with the pilot cross bore1051when the spool1031is in the neutral position.

The pressure control valve1025ofFIG.16is similar in construction and function to the pressure control valve25ofFIG.1in other respects, as will be appreciated by one skilled in the art.

Referring toFIGS.18and19, another embodiment of a hydraulic cartridge valve1225constructed in accordance with principles of the present disclosure is shown. The hydraulic cartridge valve1225is illustrated in a neutral position. The illustrated valve1225comprises a pilot-operated proportional pressure control valve that includes a main stage1227and a pilot stage1228. The illustrated pressure control valve1225includes a body1230, a spool1231, a biasing element1232in the form of a spring, a pilot flow valve assembly1234, and means for restricting pilot flow through the pilot flow passage in the form of a pilot flow control assembly1235.

In the illustrated embodiment, the main stage1227of the pressure control valve1225comprises the cage1240of the body1230, the spool1231, and the biasing member1232. The cage1240is hollow and is configured to be inserted into a cavity formed in a suitable housing such that the valve1225is in fluid communication with a hydraulic circuit within which the valve1225is intended to be used.

The pilot stage1228of the pressure control valve1225comprises the pilot flow valve assembly1234and the pilot flow control assembly1235. The pilot flow valve assembly1234is configured to selectively occlude the pilot flow passage1250defined by the cage1240of the body1230. In the illustrated embodiment, the pilot flow valve assembly1234is configured to selectively prevent pilot flow from the pilot flow passage1250out the tank port4.

Referring toFIGS.18and19, the pilot flow control assembly1235includes the body1230, the spool1231, and a control element1302mounted to the body1230. The body1230defines the pilot flow passage1250. The body1230includes an interior bore surface1248defining an interior groove1249(seeFIG.19). The interior groove1249is in fluid communication with the pilot flow passage1250and is open to the interior bore surface1248.

The spool1231includes a pilot land1253. The pilot land1253of the spool1231and the interior bore surface1248of the body1230define the restriction1215. The pilot land1253is disposed axially between the interior groove1249of the body1230and the control element1301when the spool1231is in the neutral position. The interior groove1249of the body1230is disposed axially between the pilot land1253and the control element1301when the spool1231is in the shifted position such that the restriction1215is no longer part of the pilot flow passage1250.

The pressure control valve1225ofFIG.18is similar in construction and function to the pressure control valve25ofFIG.1in other respects, as will be appreciated by one skilled in the art.

Referring toFIG.20, an embodiment of a hydraulic control system1400constructed according to principles of the present disclosure is shown. The illustrated hydraulic control system1400includes a pump1401, a tank1402, a pair of actuators1403,1404, a pair of hydraulic cartridge valves1425,1426constructed according to principles of the present disclosure, and a controller1429(also referred to as an electronic control unit (ECU).

In the illustrated embodiment, the pump1401is adapted to provide a source of pressurized fluid. The pump1401is adapted to receive a supply of fluid from the tank1402and to discharge a flow of fluid therefrom. The pump1401is in selective fluid communication with the pair of actuators1403,1404via the pair of valves1425,1426, respectively, to selectively deliver a flow of hydraulic fluid to the actuators1403,1404.

The pump1401is in fluid communication with the tank1402, which is adapted to hold a reservoir of fluid. In embodiments, the tank1402can be in fluid communication with the pump1401via any suitable technique. For example, in embodiments, the pump1401is in fluid communication with the tank1402via a pump supply line1410to receive a return flow of hydraulic fluid from the tank1402, which in turn can be used by the pump1401to deliver the flow of hydraulic fluid to the actuators1403,1404.

In embodiments, the pump1401can be any suitable pump that is acceptable for the intended application, as will be readily understood by one skilled in the art. In embodiments, the pump1401can be a fixed-displacement pump or a variable-displacement pump.

In embodiments, the tank1402is adapted to hold a reservoir of fluid. In embodiments, the tank1402can be any suitable tank known to those skilled in the art. In embodiments, the tank1402comprises a reservoir of hydraulic fluid which can be drawn into the pump1401in order to generate a flow of hydraulic fluid for the system.

In embodiments, each actuator1403,1404is in selective fluid communication with the pump1401. In the illustrated embodiment, the actuators1403,1404are in selective fluid communication with the pump1401and the tank1402via the pair of valves1425,1426, respectively. In embodiments, the actuators1403,1404are adapted to use hydraulic power to perform a mechanical work operation. In embodiments, each actuator1403,1404can be any suitable actuator for use in a hydraulic control system compatible with a control valve constructed according to principles of the present disclosure.

In the illustrated embodiment, each of the pair of actuators1403,1404comprises a transmission clutch control which have a similar construction and functionality. Each actuator1403,1404defines a chamber1410therein adapted to receive pressurized fluid. A flow of hydraulic fluid into the chamber1410of the actuator1403,1404can cause the actuator1403,1404to operate once the pressure in the chamber1410overcomes a bias member1411. The bias member1411of the actuator1403,1404is configured to urge the hydraulic fluid from the chamber1410. An actuator port1412of the actuators1403,1404leading to the chamber1410is in fluid communication with a respective one of the pair of valves1425,1426to selectively receive a supply flow of pressurized hydraulic fluid from the pump1401or to selectively discharge a discharge flow of hydraulic fluid from the chamber1410of the actuators1403,1404to the tank1402.

In embodiments, each pressure control valve1425,1426is in fluid communication with the pump1401, the tank1402, and the actuator1403,1404with which the respective pressure control valve1425,1426is associated. In embodiments, each pressure control valve1425,1426is interposed between the pump1401and the respective actuator1403,1404and between the respective actuator1403,1404and the tank1402.

In the illustrated embodiment, the valves1425,1426are each in electrical communication with the controller1429and in fluid communication with the pump1401and the tank1402. The pair of valves1425,1426are respectively interposed between the pump1401and one of the pair of actuators1403,1404. The valves1425,1426are adapted to selectively direct the flow of fluid from the pump1401to the chamber1410of the respective actuator1403,1404with which the valve1425,1426is associated. The pair of valves1425,1426are respectively interposed between one of the pair of actuators1403,1404and the tank1402. The pair of valves1425,1426are adapted to selectively direct a return flow of fluid from the chamber1410of the respective actuator1403,1404with which the valve1425,1426is associated to the tank1402.

In the illustrated embodiment, each of the valves1425,1426comprises a valve substantially shown inFIG.1and as described above. Each valve1425,1426includes a body, a spool, a biasing element in the form of a spring, a pilot flow valve assembly, and a pilot flow control assembly as described above in connection with the embodiment of a valve shown inFIG.1. The body defines an axial bore, a supply port2, a work port3, and a tank port4. Each of the supply port2, the work port3, and the tank port4are in fluid communication with the axial bore. The supply port2is in fluid communication with the pump1401. The work port3is in fluid communication with the chamber1410of the respective actuator1403,1404with which the valve1425,1426is associated. The tank port4is in fluid communication with the tank1402.

The spool is disposed within the axial bore of the body and axially movable over a range of travel between a neutral position and a shifted position. In the neutral position, the supply port2and the work port3are in fluid isolation from each other and the work port3and the tank port4are in fluid communication with each other to thereby fluidly connect the chamber1410of the respective actuator1403,1404with which the valve1425,1426is associated to the tank1402. In the shifted position, the supply port2and the work port3are in fluid communication with each other to thereby fluidly connect the pump1401to the chamber1410of the respective actuator1403,1404with which the valve1425,1426is associated and the work port3and the tank port4are in fluid isolation from each other.

The spool and the body cooperate together to define a pilot flow passage in fluid communication with the supply port2and the tank port4when the spool is in the neutral position. The spring is operatively arranged with the spool to bias the spool to the neutral position.

The valves1425,1426can be similar in other respects to the valve ofFIG.1. For example, the pilot flow valve assembly and the pilot flow control assembly of the valves are substantially the same as the valve ofFIG.1.

The controller1429is in electrical communication with the pump1401and the valves1425,1426. The controller1429is configured to selectively operate the actuators1403,1404by controlling the hydraulic cartridge valves1425,1426in response to a suitable input received by the controller1429, and as will be readily appreciated by one skilled in the art.

In embodiments, the controller1429is configured to selectively send a drive signal to the coil of one or both of the actuators1425,1426in response to a predetermined input. The drive signal can comprise a variable electrical current. The controller1429can be configured to vary the electrical current passed through the coil of each of the valves1425,1426based upon the input received by the controller1429.

In embodiments, the controller1429can be any suitable electronic control unit or units as will be readily familiar to one skilled in the art. For example, in embodiments, the controller1429can comprise a suitable, commercially available plug-in style, microprocessor based valve driver. In embodiments, the controller1429can includes a valve driver operably arranged with each valve coil to selectively operate the cartridge valves.

In embodiments, the controller1429is configured to receive an input indicating a desired operational characteristic. For example, in embodiments, the controller1429includes a suitable graphical user interface configured to allow an operator to enter a desired set point for the cartridge valve12. In embodiments, the controller1429can be in electrical communication with other components, such as, when the hydraulic control system1400is used as an on-board control mechanism for a mobile machine, for example.

It will be understood that, in other embodiments, the hydraulic control system1400can be configured to selectively and independently operate a plurality of hydraulic cartridge valves constructed according to principles of the present disclosure. It will be understood that, in embodiments, the hydraulic control system1400can include other and different components.

Embodiments of a hydraulic control system constructed according to principles of the present disclosure can be used to carry out a method of controlling a hydraulic actuator using an embodiment of a cartridge valve as described above. In embodiments, a method of controlling a hydraulic actuator following principles of the present disclosure can use any embodiment of a hydraulic cartridge valve and/or any embodiment of a hydraulic control system constructed according to principles discussed herein.

In one embodiment, when the valve is de-energized (neutral position) with pressure applied at the supply port2, hydraulic fluid flows from the supply port2to the tank port4. The hydraulic fluid can pass through a filter screen outside the cage of the valve, then through a second filter attached to the spool. After the hydraulic fluid is filtered, it flows through the drilled first orifice defined in the spool and passes through the pilot flow passage defined axially in the spool. The hydraulic fluid then passes through the leakage control elements and then passes by the ball and out the tank port4to the tank. The leakage control elements form a second orifice in the pilot flow passage in serial relationship with the first orifice to restrict the amount of pilot flow when the valve is in the de-energized state.

In embodiments, a controller can selectively operate the valve by directing a drive current through the coil of the valve. Once the valve is energized, the leakage control orifice is “de-activated” as the leakage control element mounted to the spool (e.g., a restriction member) moves axially away from the leakage control element mounted to the body (e.g., a pilot pin). The amount of additional restriction results in a trade-off between leakage reduction and response time of the valve. The pilot flow from the supply port2to the tank port4is reduced via the leakage control elements as compared to a valve not containing these leakage control elements. The work port3is connected to the tank port4.

As current is applied to the coil, a magnetic force is established between the armature and the frame pulling the armature toward the frame pole piece face. As the armature moves, so does the pilot pin which seats the ball, blocking the flow of hydraulic fluid past the ball. The pilot chamber (volume between the seat and the spool) begins to fill and pressurize, thereby causing the spool to move down and compress the spring. If sufficient current is applied to the coil, the spool will compress the spring to the point where the spool moves to the shifted position to fluidly connect the supply port2to the work port3. The amount of current required to build this pressure under the ball is called threshold current. As the ball begins to lift off the seat, the magnetic force of the proportional actuator regulates the pressure in the pilot chamber which regulates the position of the spool. Once the pressure in the work port3reaches the desired level, the spool will move between a reducing position and a relieving position.

In embodiments, the valve is used with a supply pressure that is at least one bar higher than the maximum reduced pressure at the work port3. Under such conditions, the bias element keeps the valve closed (blocking the supply and work port3) when no current is applied to the coil.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.