System and method for control valve with integrated bleed valve

Abstract

The control valve includes a poppet valve assembly having an integrated bleed valve function. The control valve includes a valve body defining a first port and a second port in communication with the first bore. The main poppet valve is movable within the first bore to selectively couple the first port and the second port and define a control chamber within the first bore. The main poppet valve defines a second bore extending through the main poppet valve to allow fluid flow from the control chamber to the second port. A bleed poppet valve is movable within the second bore to selectively couple the control chamber to the second port via the second bore. The bleed poppet valve defines a third bore extending through the first poppet valve to allow fluid flow from the control chamber to the second port.

Description

Cross - Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 418,335, filed on October 21, 2022, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] The present disclosure generally relates to hydraulic control components for hydraulic systems. More specifically, the present disclosure relates to systems and methods for thermal relief of control valves. Summary of the Invention

[0003] A control valve (e.g., an electro - hydraulic proportional valve (EHPV)) can be a two - stage proportional valve with a variable flow restriction, where a smaller solenoid - operated pilot stage controls a larger main lift valve by engaging a pilot seat formed in the main lift valve. A relief valve can be a valve that will open within a certain pressure range to allow fluid to flow to a low - pressure chamber. Aspects of the present disclosure provide a system that combines these two functions by coupling the lift valve of the relief valve with the seat of the pilot stage of the control valve. Thus, a control valve according to the present disclosure can provide the ability to relieve pressure increases due to thermal expansion of the fluid in applications with cylinder - mounted load holding.

[0004] According to one aspect of the present disclosure, a control valve can include a valve body that can define a first bore, a first port and a second port in communication with the first bore, and a first seat between the first bore and a second bore. A first lift valve can be movably disposed within the first bore to selectively engage and disengage the first seat and define a control chamber within the first bore that is opposite the second port. The first lift valve can define a second bore and a second seat and a third seat, the second bore can extend through the first lift valve to couple the control chamber to the second port, and the second seat and the third seat are formed within the second bore. A second lift valve is movably disposed within the second bore to selectively engage and disengage the second seat. A first biasing member can extend between the third seat and the second lift valve to bias the second lift valve into engagement with the second seat.

[0005] In some non - limiting examples, the second lift valve defines a third bore that can extend through the second lift valve. The second lift valve can be configured as a check valve that is movably disposed within the third bore to selectively engage and disengage a fourth seat that can be formed within the third bore to allow fluid to flow from the control chamber to the second port. The first biasing member can be configured to hold the check valve within the third bore. In some cases, the control valve can further include a control passage that can extend between the control chamber and the first port. The control passage can be formed within the first lift valve.

[0006] In some non - limiting examples, when the first lift valve engages the first seat, the second lift valve can be configured to selectively disengage from the second seat based on a pressure difference between the control chamber and the second port to allow fluid to flow from the control chamber to the second port. When the first lift valve disengages from the first seat, the second lift valve can be configured to engage the second seat to block fluid flow from the second port to the control chamber. In some cases, the control valve can further include a second biasing member disposed within the first bore. The second biasing member can be configured to bias the first lift valve into engagement with the first seat.

[0007] In some non - limiting examples, the control valve can further include a third lift valve configured to selectively engage and disengage from a fifth seat defined by the second lift valve to selectively engage and disengage the first lift valve from the first seat. When the third lift valve engages the fifth seat, the third lift valve can block fluid flow from the control chamber to the second port such that the pressure difference between the control chamber and the second port biases the first lift valve into engagement with the first seat. When the third lift valve disengages from the fifth seat, fluid can flow from the control chamber to the second port such that the pressure in the control chamber is reduced and the pressure difference between the control chamber and the second port biases the first lift valve to disengage from the first seat. In some cases, an actuator can be configured to move the third lift valve to selectively engage and disengage the third lift valve from the fifth seat. A third biasing member can be configured to bias the third lift valve into engagement with the fifth seat, wherein the actuator can be configured to compress the third biasing member to disengage the third lift valve from the fifth seat. The actuator can be configured as a solenoid including an armature and a coil, wherein energization of the coil causes the armature to move to compress the third biasing member. The third biasing member can extend between the body of the solenoid and the third lift valve, and the third lift valve can extend through the armature.

[0008] According to another aspect of the present disclosure, the control valve can include a valve body that can define a first port and a second port in communication with the first bore. A main lift valve is movably disposed within the first bore to selectively couple the first port and the second port and defines a control chamber within the first bore that is opposite the second port and in fluid communication with the first port. The main lift valve can define a second bore that can extend through the main lift valve to allow fluid to flow from the control chamber to the second port. A bleed lift valve can be movably disposed within the second bore to selectively couple the control chamber to the second port via the second bore. The bleed lift valve can define a third bore that can extend through the first lift valve to allow fluid to flow from the control chamber to the second port. A pilot lift valve can be movably disposed within the first bore to selectively couple the control chamber to a third port via the third bore.

[0009] In some non-limiting examples, the control valve may further include a check valve disposed within the bleed lift valve to block fluid flow from the second port to the control chamber. The main lift valve may be configured to couple the first port to the second port based on at least one of: a first pressure differential between the control chamber and the second port to allow fluid to flow from the first port to the second port, and a second pressure differential between the first port and the second port to allow fluid to flow from the second port to the first port. The bleed lift valve may be configured to couple the control chamber to the second port via the second orifice based on the pressure differential between the control chamber and the second port when the first port and the second port are blocked by the main lift valve. When the pilot lift valve moves to couple the control chamber to the second port via the third orifice, the pressure differential between the control chamber and the second port causes the main lift valve to move to couple the first port to the second port. In some cases, the control valve may further include an actuator configured to move the pilot lift valve to selectively couple the control chamber to the second port via the third orifice.

[0010] In some non-limiting examples, a first biasing member may be configured to bias the main lift valve to block the first port from the second port. The first biasing member may be retained within the control chamber. A second biasing member may be configured to bias the bleed lift valve to block the control chamber from the second port. The second biasing member may be retained within the second orifice. A third biasing member may be configured to bias the pilot lift valve to block the control chamber from the second port.

[0011] According to another aspect of the present invention, a control valve may include a valve body that may define a first orifice, a first port and a second port in communication with the first orifice, and a main seat between the first port and the second port. A lift valve assembly may be movably disposed within the first orifice. The lift valve assembly may include a first end and a second end, the first end configured to engage the main seat to selectively couple the first port and the second port, and the second end configured to define a control chamber within the first orifice opposite the second port. A passageway may extend between the first end and the second end, and a pilot seat may be formed on the second end between the control chamber and the passageway. A pilot lift valve may be movably disposed within the control chamber and may be configured to engage the pilot seat to selectively couple the control chamber to the second port via the passageway. The lift valve assembly may include a main lift valve and a bleed lift valve. The main lift valve may be configured to engage the main seat and may define a second orifice forming the passageway and a bleed seat within the second orifice. The bleed lift valve may be movably disposed within the second orifice to selectively engage the pilot seat. The bleed lift valve may define the pilot seat and a third orifice forming the passageway. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be better understood when considering the following specific embodiments thereof, and features, aspects, and advantages other than those described above will also become apparent. Such specific embodiments refer to the following drawings.

[0013] Figure 1 is a cross-sectional view of a non-limiting example of a valve with an integral thermal relief according to an aspect of the present disclosure.

[0014] Figure 2 is Figure 1 a detailed view of the valve taken along line II-II.

[0015] Figure 3 is Figure 1 a detailed view of the valve in which the relief lift valve is configured to provide threshold compensation. Specific Embodiments

[0016] Before elaborating on any aspect of the present disclosure, it should be understood that the present disclosure is not limited in its application to the details of the construction and arrangement of components set forth in the following description or shown in the drawings. The present disclosure is capable of other constructions and of being practiced or carried out in various ways. Also, it should be understood that the terminology and phrases used herein are for the purpose of description and should not be regarded as limiting. As used herein, the terms "including", "comprising", or "having" and their variants are intended to cover the items listed thereafter and their equivalents as well as additional items. Unless otherwise specified or limited, the terms "mounted", "connected", "supported", and "coupled" and their variants are used broadly and cover both direct and indirect mounting, connection, support, and coupling. Further, "connected" and "coupled" are not limited to physical or mechanical connection or coupling.

[0017] As used herein, unless otherwise defined or limited, for ease of reference, the ordinal numbers used herein are generally based on the order of the particular components presented in the relevant portion of the present disclosure. In this regard, for example, names such as "first", "second", etc. generally only indicate the order in which the relevant components are introduced into the discussion and generally do not indicate or require a particular spatial arrangement, functional or structural primacy, or order.

[0018] The following discussion is presented to enable a person skilled in the art to make and use aspects of the present disclosure. Various modifications to the illustrated constructions will be readily apparent to those skilled in the art, and the general principles herein can be applied to other constructions and applications without departing from the aspects of the present disclosure. Thus, the aspects of the present disclosure are not intended to be limited to the constructions shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description should be read with reference to the accompanying drawings, in which like elements in different drawings are identified by the same reference numerals. The drawings are not necessarily drawn to scale, which depict selected constructions and are not intended to limit the scope of the present disclosure. Those skilled in the art will recognize that the non-limiting examples provided herein have many useful alternatives and fall within the scope of the present disclosure.

[0019] A valve can be used to control fluid flow in a hydraulic system. Generally, the valve can include a control element that can move within a valve body (such as a sleeve or valve section) to selectively couple and decouple a first working port from a second working port to control fluid flow therebetween. In some cases, the control element can be moved based on a pressure differential across the control element. For example, the pressure in a control chamber of the valve can be adjusted to move the control element between a first position and a second position, where in the first position the first working port is decoupled from the second working port and in the second position the first working port is coupled to the second working port. However, the pressure in the control chamber can fluctuate with the temperature of the fluid therein. Thus, as the fluid warms up (e.g., due to thermal expansion of the fluid), the local pressure in the control chamber can spike. For example, if the hydraulic system is not operating, or is starting up or shutting down, the fluid velocity in the valve can be zero or near zero, and the fluid in the control chamber can warm up. If the pressure generated is not relieved, the control element can lock up, or the valve or other components can be damaged.

[0020] To prevent this, the hydraulic system can include a thermal relief valve that can allow a small flow of fluid from the control chamber and provide thermal relief protection. Generally, to provide thermal relief, the valve can be coupled to a separate external thermal relief valve. However, the increased size and complexity of the external thermal relief valve can limit the use of these types of valves. For example, in the case where the valve is used in a cylinder-mounted application, more specifically, in the case where the valve is coupled to a load-holding application of a hydraulic actuator via hard tubing, conventional designs can be difficult to use.

[0021] Aspects of the present disclosure can provide improved methods and systems for thermal relief by providing an integral thermal relief valve within a main valve. More specifically, the thermal relief valve can be provided with a control element of the valve to allow thermal relief from a control chamber to a working port. For example, an improved poppet valve assembly can be provided for a valve (e.g., an electrohydraulic proportional valve (EHPV)), which can be configured to relieve local pressure within the valve control chamber caused by thermal expansion. In particular, some embodiments allow pressure to relieve within the valve by forming a passageway in the poppet valve assembly. Accordingly, the system can provide a method of relieving pressure caused by thermal expansion within a single valve element. The relief valve can be configured to provide a low flow rate to relieve fluid expansion while allowing relatively large manufacturing tolerances, resulting in a compact, simple device.

[0022] For example, the poppet valve assembly can be movable within a main bore (e.g., a first bore) of the valve body to selectively couple a first port and a second port to control flow between a first working port and a second working port. Accordingly, the poppet valve assembly can at least partially isolate a portion of the main bore to define a control chamber using the main bore (e.g., by engaging and disengaging a first seat formed in the valve body). The control chamber can be in fluid communication with the first port such that the poppet valve assembly can move based on a pressure differential between the control chamber and the other of the second working port. To provide thermal relief for the control chamber, the poppet valve assembly can include a main poppet valve (e.g., a first poppet valve) that defines a second bore extending from the control chamber through the main poppet valve to the second working port. Accordingly, a relief poppet valve (e.g., a second poppet valve) can be movably retained within the second bore to engage and disengage a seat (e.g., a second seat) formed therein. The relief poppet valve can be biased by a biasing member (e.g., a spring or other elastic member) to engage the seat to prevent flow from the control chamber to the second port during normal operation. However, if the pressure within the control chamber increases due to thermal expansion of the fluid, the pressure can act on the relief poppet valve to overcome the biasing force of the biasing member, causing the relief poppet valve to disengage from the second seat and open a passageway between the control chambers to allow fluid to flow from the control chamber to the second port (e.g., around the relief poppet valve).

[0023] Figure 1 and Figure 2Shows a non - limiting example of a valve 100 (e.g., a control valve) with an integral thermal relief according to aspects of the present disclosure. More specifically, as will be described in more detail below, the control element within the valve 100 can include an internal thermal relief valve that is configured to connect various ports or control chambers to relieve pressure due to the thermal expansion of the working fluid. Thus, the valve 100 can combine the functions of a conventional control valve and a relief valve into a single device. In the non - limiting example shown, the valve 100 is configured as a two - stage proportional valve with variable flow restriction, where a smaller solenoid - operated pilot stage can control a larger lift valve. However, the principles described herein can also be applied to other types of control valves.

[0024] Generally, the valve 100 includes a valve body 104 that defines one or more ports (e.g., a working port, a tank port, a pump port, etc.) that can be selectively coupled and decoupled to control fluid flow within a hydraulic system. In some non - limiting examples, the valve body 104 can be part of a valve section (e.g., integral with the valve section) such that any component of the valve 100 can be directly mounted into the valve section. In other non - limiting examples, the valve body 104 can be configured as a valve sleeve that is received within the valve section, allowing for easier replacement of the entire control valve.

[0025] In the non - limiting example shown, the valve body 104 defines a first port 106 (e.g., a first working port) and a second port 108 (e.g., a second working port). Here, the first port 106 is a side port disposed on one side of the valve body 104, and the second port 108 is a nose port disposed at the end (e.g., the nose of the valve body) of the valve body 104. Within the valve body 104, the valve 100 can define a main bore 110 (e.g., a first bore) that extends along the axis 112 of the valve body 104. The first port 106 and the second port 108 can be in communication with each other such that fluid can flow between the first port 106 and the second port 108 via the main bore 110. Here, the first port 106 is axially aligned with the main bore 110, and the second port is radially aligned with the main bore 110. In other non - limiting examples, the ports can be arranged differently and can include more than two ports.

[0026] As generally discussed above, a control valve can include a control element configured to selectively couple two or more ports. More specifically, the control element can be movably disposed within a bore of a valve body to selectively couple the ports. In the non-limiting example shown, valve 100 includes a control element configured to lift valve assembly 116. Lift valve assembly 116 is movably disposed within main bore 110 to selectively couple first port 106 and second port 108. More specifically, lift valve assembly 116 can move along axis 112 relative to a main seat 120 (e.g., a first seat or a primary seat) defined by valve body 104. As shown, main seat 120 can be positioned within main bore 110 between first port 106 and second port 108. Accordingly, lift valve assembly 116 can define a first end 122 and a second end 124 opposite first end 122. Lift valve assembly 116 can move between a first position and a second position, in the first position, the first end engages main seat 120 to decouple first port 106 from second port 108, and in the second position, the first end disengages from main seat 20 to couple first port 106 to second port 108 and allow fluid to flow therebetween.

[0027] In some cases, the control element can be configured to move based on the pressure of fluid within the valve to selectively couple the ports. That is, the control element can be a pilot-operated control element, where a pilot lift valve can be operated to control the pressure within a control chamber. In the non-limiting example shown, lift valve assembly 116 is configured to move based on the pressure within control chamber 128 defined within main bore 110. More specifically, lift valve assembly 116 is configured to (e.g., at second end 124 of the lift valve assembly) at least partially isolate an area of main bore 110 to define control chamber 128 within main bore 110. Thus, control chamber 128 can be jointly defined by sides of main bore 110 and second end 124 of lift valve assembly 116.

[0028] As shown, the second port 108 is located at the first end 122 of the lift valve assembly 116, and the control chamber 128 is located at the second end 124 of the lift valve assembly 116. Accordingly, the lift valve assembly 116 can move based on the pressure differential between the control chamber 128 and the first port 106 and the second port 108. The force balance on the lift valve assembly 116 is the pressure acting on the second end 124 of the lift valve assembly 116 multiplied by the area of the full diameter of the lift valve assembly 116 (e.g., the pressure in the control chamber 128 used to move the lift valve assembly 116 to the first position to engage the main seat and close the valve 100), versus the pressure at the first port 106 multiplied by the annular area (e.g., the area of the full diameter of the lift valve assembly minus the area of the seat diameter) plus the pressure at the second port 108 multiplied by the area of the diameter of the main seat 120 (e.g., the pressures from the first port 106 and the second port 108 act together to move the lift valve assembly 116 to the second position to disengage the main seat 120 and open the valve 100).

[0029] Accordingly, pressure can be provided from one of the ports to the control chamber and vented to the other of the ports to move the lift valve assembly. In the non-limiting example shown, the control chamber 128 is coupled to the first port 106 via an orifice 132 such that fluid and pressure communicate from the first port 106 to the control chamber 128. The orifice 132 is disposed in the lift valve assembly 116 but could alternatively be disposed in another component, such as the valve body 104. To vent the pressure within the control chamber 128, the lift valve assembly 116 can define a passageway 136 (e.g., a vent passageway) that extends through the lift valve assembly 116 (e.g., from the first end 122 to the second end 124) to couple the control chamber 128 to the second port 108.

[0030] By selectively blocking passageway 136, the pressure within control chamber 128 can be regulated to control the movement of lift valve assembly 116. For example, by blocking passageway 136 to disconnect control chamber 128 from second port 108, fluid can flow into control chamber 128 from first port 106 to establish pressure within control chamber 128 and bias lift valve assembly 116 to a first position (e.g., to engage main seat portion 120 and disconnect first port 106 from second port 108). However, by opening passageway 136 to connect control chamber 128 to second port 108, fluid can flow from control chamber 128 to second port. Since passageway 136 is configured to have a lower pressure drop than orifice 132 (e.g., orifice 132 has a larger cross-sectional area), fluid can flow out of passageway 136 more quickly than it can through orifice 132, and control chamber 128 will drain, reducing the pressure therein. Accordingly, the pressure at first end 122 (e.g., the pressure from first port 106 and second port 108) will bias lift valve assembly 116 to a second position (e.g., to disengage main seat portion 120 and connect first port 106 to second port 108).

[0031] As described above, a pilot lift valve 140 can be provided to selectively connect control chamber 128 to second port 108 (e.g., to selectively open or block passageway 136). As shown, pilot lift valve 140 is movably disposed within main bore 110 to engage and disengage a pilot seat portion 142 formed in second end 124 of lift valve assembly 116 (e.g., move along an axis between a first engaged position and a second disengaged position). When engaged with pilot seat portion 142, pilot lift valve 140 blocks passageway 136 to disconnect control chamber 128 from second port 108. When disengaged from pilot seat portion 142, pilot lift valve opens passageway 136 to connect control chamber 128 to second port 108.

[0032] In some cases, the pilot lift valve can be operated (e.g., moved) by an actuator. In the non-limiting example shown, the pilot lift valve 140 is a solenoid-operated pilot lift valve. Thus, the valve 100 can include a solenoid 144 that is coupled to the valve body 104 to move the pilot lift valve 140. In this case, the pilot lift valve 140 is coupled to the armature 146 of the solenoid 144 and is biased by a pilot spring 148 (or another type of biasing member) to engage the pilot seat 142, which pilot spring 148 is configured to urge the pilot lift valve 140 toward the pilot seat 142. Here, the pilot spring 148 is positioned between the armature 146 and the body 150 of the solenoid 144; however, other spring arrangements can also be used. Thus, when current is applied to the coil 152 of the solenoid 144, the armature 146 moves to compress the pilot spring 148, which reduces the force on the pilot lift valve 140. Once the magnetic inductive force overcomes the spring load, the pilot lift valve 140 can begin to move out of engagement with the pilot seat 142, enabling a flow path for fluid from the control chamber 128 through the pilot seat 142 and out the second port 108. Accordingly, when the coil 152 is deactivated, the magnetic force on the armature 146 is removed, such that the spring force from the pilot spring 148 returns the armature 146 and the pilot lift valve 140 to engagement with the pilot seat 142.

[0033] In some cases, particularly when the lift valve assembly 116 engages the main seat 120 to block the first port 106 and the second port 108 and little fluid passes through the valve 100, heating of the fluid within the control chamber 128 can cause thermal expansion of the fluid and a corresponding pressure surge. To prevent overpressure conditions within the valve 100 due to thermal expansion, the lift valve assembly 116 can be configured with an integral relief valve. A relief valve is a valve that opens within a predetermined pressure range to allow fluid to flow from the control chamber to a lower pressure region.

[0034] According to the present disclosure, the relief valve can be configured as a relief lift valve disposed within a larger main lift valve (e.g., the main control element). The relief lift valve can be configured to be in hard contact with an outer seat within the main lift valve under normal operating and temperature conditions and to move away from the seat to relieve pressure from thermal expansion. In some cases, the relief lift valve can be biased by a biasing member (such as a spring or other elastic member) to engage the seat. Still referring to Figure 1 and Figure 2, the lift valve assembly 116 can include a main lift valve 160 that is movably disposed in the main bore 110 and configured to selectively couple the first port 106 and the second port 108, and the main lift valve defines a control chamber 128 within the main bore 110. Accordingly, the main lift valve 160 defines a first end 122, a second end 124, and an orifice 132. Additionally, the main lift valve 160 defines a second bore 162 that forms at least a portion of the passageway 136 such that the second bore 162 can at least partially coextend with the passageway 136. In other non-limiting examples, the second bore 162 can be separated from the passageway 136.

[0035] To provide pressure relief due to thermal expansion, a bleed lift valve 164 can be movably disposed within the second bore 162. More specifically, the bleed lift valve 164 can move within the second bore 162 to selectively engage and disengage a bleed seat 166 (e.g., a second seat) defined within the second bore 162. As shown, the bleed lift valve 164 defines a first end 168 and a second end 170, with the first end 168 configured to engage the bleed seat 166 and the second end 170 opposite the first end 168. Additionally, in the illustrated non-limiting example, the bleed lift valve 164 defines a third bore 172 that extends from the first end 168 through the bleed lift valve 162 to the second end 170. The third bore 172 forms at least a portion of the passageway 136 such that the third bore 172 can at least partially coextend with the passageway 136. In some instances, when the first end 168 engages the bleed seat 166, the first end 168 of the bleed lift valve 164 can be configured to form a pilot seat 142. The portion of the first end 168 that forms the pilot seat 142 can be exposed to at least partially define the control chamber 128. Specifically, when the pilot lift valve 140 disengages from the pilot seat 142 (e.g., the bleed lift valve 164), fluid can be discharged through the third bore 172 and the second bore 162 for evacuation to the second port 108. In other non-limiting examples, particularly where the second bore 162 does not form part of the passageway 136, the bleed lift valve 164 can be configured differently. For example, the bleed lift valve may not include the third bore.

[0036] In some cases, the bleed lift valve can be configured as a spring-biased, normally-closed lift valve. For example, in the non-limiting example shown, a biasing member configured at the bleed spring 176 is disposed within the second bore 162 and is configured to bias the bleed lift valve 164 into engagement with the bleed seat 166. The bleed spring 176 is positioned to extend between the bleed lift valve 164 and the second port 108. More specifically, the bleed spring 176 extends between a second end 170 of the bleed lift valve 164 that forms a first spring seat 178 and a second spring seat 180 formed within the second bore 162. In this case, the second spring seat 180 is formed near a first end of the main lift valve 160 (e.g., the lift valve assembly 116). As shown, in some non-limiting examples, the second spring seat 180 can be formed by a retainer 182 (e.g., a spring retainer) configured to be coupled to the main lift valve 160. For example, the retainer 182 can be configured to receive (e.g., via threading, press fitting, or other types of connections) within the second bore 162 in a releasable or non-releasable manner. In this way, the bleed lift valve 164 and the bleed spring 176 can be installed and retained within the second bore 162. Additionally, the retainer 182 can be fixed or adjustable (e.g., using a lock nut arrangement) such that the position of the second spring seat 180 relative to the first spring seat 178 can be adjustable (e.g., to adjust the opening pressure of the bleed lift valve 164).

[0037] Correspondingly, when retained in the second bore 162, the bleed spring 176 can be pre-compressed to control the opening pressure of the bleed valve function. That is, the bleed spring 176 and the bleed lift valve 164 can be configured such that the bleed lift valve 164 disengages from the bleed seat 166 at a predetermined opening pressure (e.g., the pressure differential between the control chamber 128 and the second port 108). The opening pressure is based on the area of the bleed lift valve 164 exposed to the control chamber 128 and the preload of the bleed spring 176 (e.g., the spring force of the bleed spring 76). When the pressure differential between the control chamber 128 and the second port 108 reaches or exceeds the opening pressure, the fluid pressure acting on the first end 168 of the bleed lift valve 164 (e.g., the fluid pressure from the control chamber 128) can overcome the preload on the bleed spring 176 plus the pressure acting on the second end 170 of the bleed lift valve 164 (e.g., the pressure from the second port 08). This causes the bleed lift valve 164 to disengage from the bleed seat 166 and further compress the bleed spring 176. When the bleed lift valve 164 moves away from the bleed seat 166 (e.g., along the axis 112), fluid from the control chamber 128 can flow around the bleed lift valve 164 within the second bore 162, thereby reducing the pressure in the control chamber 128. Accordingly, the second bore or the bleed valve can be configured to allow flow around the bleed lift valve 164. For example, the bleed lift valve 164 can define one or more channels 186 in its outer surface that serve as flow passages, or the second bore 162 can define a region of increasing cross-sectional area that allows flow around the bleed lift valve 164.

[0038] In some non-limiting examples, the valve according to the present disclosure can be configured to allow bidirectional flow between the first port and the second port. However, when the pressure in the second port is greater than the pressure in the first port, the control chamber will be connected to the second port when the pilot lift valve disengages from the pilot seat. This can allow flow from the second port to the control chamber, which can raise the pressure in the control chamber 128 to the pressure of the second port 108. Thereby, the pressure in the control chamber 128 can bias the lift valve assembly 116 to remain closed (e.g., to engage the main seat 120). In this case, the flow may be restricted to flow from the second port 108 through the pilot seat 142 and through the orifice 132 to the first port 106, which may result in very restricted flow in that direction. Accordingly, it may be desirable to prevent backflow from the second port 108 to the control chamber 128 such that the pressure in the control chamber 128 is determined by the pressure in the first port 106. To prevent backflow from the second port 108 to the control chamber 128, a check valve 188 can be provided within the passageway 136 to allow unidirectional flow from the control chamber 128 to the second port 128.

[0039] In the illustrated non - limiting example, a check valve 188 is disposed within a third bore 172 of the bleed lift valve 164, where the check valve can be held by a bleed spring 176. Accordingly, the third bore 172 can define a seat 190 therein, and the check valve 188 can move within the third bore 171 to selectively engage and disengage from the seat 190 based on a pressure differential between the second port 108 and the control chamber 128. Thus, when fluid flows from the first port 106 to the second port 108, the check valve 188 disengages from the seat 190 to permit flow through the bleed lift valve 164 (e.g., the lift valve assembly 116). Conversely, when fluid flows from the second port 108 to the first port 106, the check valve 188 engages the seat 190 to block flow through the bleed lift valve 164.

[0040] As generally discussed above, the valve 100 can operate between various configurations to control the flow through the valve 100. In a first configuration (e.g., a closed configuration), the valve 100 can be configured to decouple the first port 106 from the second port 108 and to decouple the control chamber 128 from the second port 108. In the first configuration, the lift valve assembly 116 is closed with the main lift valve 160 engaged with the main seat 120 and the bleed lift valve 164 engaged with the bleed seat 166. In this manner, the main lift valve 160 blocks the flow between the first port 106 and the second port 108, while the bleed lift valve 164 blocks the flow from the control chamber 128 through the second bore 162 of the main lift valve 160 (e.g., around the bleed lift valve 164 and through the bleed seat 166) to the second port 108. Additionally, the pilot lift valve 140 engages the pilot seat 142 to block the flow from the control chamber 128 through the third bore 172 to the second port 108.

[0041] To place the valve 100 in the first configuration, the solenoid 144 can be de-energized so that the pilot spring 148 biases the pilot lift valve 140 into engagement with the pilot seat 142. This blocks the third orifice 172 to prevent fluid from flowing out of the control chamber 128. Since the control chamber 128 remains connected to the first port 106 via the orifice 132, fluid will continue to flow from the first port 106 into the control chamber 128. This causes the pressure within the control chamber 128 to increase. With respect to the main lift valve 160, once the force associated with the pressure in the control chamber 128 (e.g., the force at the second end 124) overcomes the forces associated with the pressures at the first port 106 and the second port 108 (e.g., the force at the first end 122), the lift valve assembly 116 is forced into engagement with the main seat 120. Thus, the lift valve assembly 116 can move (e.g., along the axis 112) within the main bore 110 to engage the main seat 120. Additionally, with respect to the bleed lift valve 164, it can be understood that the force provided by the bleed spring 176 (e.g., the force at the second end 170) can overcome the force associated with the pressure in the control chamber 128 (e.g., the force at the first end 168), which forces the bleed lift valve 164 into engagement with the bleed seat 166. Thus, the bleed lift valve 164 can move (e.g., along the axis 112, relative to the main lift valve 160) within the second bore 162 to engage the bleed seat 166.

[0042] In the second configuration (e.g., open configuration), the valve 100 can be configured to connect the first port 106 to the second port 108 and connect the control chamber 128 to the second port 108. In the second configuration, the lift valve assembly 116 is in a first open configuration, the main lift valve 160 is disengaged from the main seat 120, and the bleed lift valve 164 is engaged with the bleed seat 166. In this way, the main lift valve 160 allows flow between the first port 106 and the second port 108, while the bleed lift valve 164 blocks flow from the control chamber 128 through the second bore 162 of the main lift valve 160 (e.g., around the bleed lift valve 164 and through the bleed seat 166) to the second port 108. Additionally, the pilot lift valve 140 is disengaged from the pilot seat 142 to allow flow from the control chamber 128 through the third orifice 172 to the second port 108.

[0043] To place the valve 100 in the second configuration, the solenoid valve 144 can be energized such that the pilot spring 148 is compressed and the pilot lift valve 140 is disengaged from the pilot seat portion 142. This opens the third orifice 172 to allow fluid to flow out of the control chamber 128 to the second port 108. Since the fluid in the control chamber 128 can be discharged through the third orifice 172 at a faster rate than the fluid flowing into the control chamber 128 through the orifice 132, the amount of fluid in the control chamber 128 will decrease. This causes the pressure in the control chamber 128 to decrease. With respect to the main lift valve 160, once the force associated with the pressures at the first port 106 and the second port 108 (e.g., the force at the first end 122) overcomes the force associated with the pressure in the control chamber 128 (e.g., the force at the second end 124), the lift valve assembly 116 is disengaged from the main seat portion 120. Thus, the lift valve assembly 116 can move (e.g., along the axis 112) within the main bore 110 to disengage from the main seat portion 120. Additionally, with respect to the bleed lift valve 164, it can be understood that the force provided by the bleed spring 176 (e.g., the force at the second end 170) can overcome the force associated with the pressure in the control chamber 128 (e.g., the force at the first end 168), which forces the bleed lift valve 164 to engage the bleed seat portion 166. Thus, the bleed lift valve 164 can move (e.g., along the axis 112, relative to the main lift valve 160) within the second bore 162 to engage the bleed seat portion 166. Additionally, in a non-limiting example including the check valve 188, the check valve 188 can be disengaged from the seat portion 190 when fluid flows from the first port 106 to the second port 108, and the check valve 188 can engage the seat portion 190 when fluid flows from the second port 108 to the first port 106. In a third configuration (e.g., a bleed configuration), the valve 100 can be configured to provide thermal bleed. The third configuration can be similar to the first configuration, but the bleed lift valve 164 is disengaged from the bleed seat portion 166 to allow a small flow of fluid to be discharged from the control chamber 128 to the second port 108 to provide thermal bleed (e.g., an overpressure condition due to thermal expansion of the fluid). The first port 106 and the second port 108 can be kept disconnected by the main lift valve 160 to prevent flow between them.

[0045] Thus, in the third configuration, the valve 100 can be configured to decouple the first port 106 from the second port 108 and couple the control chamber 128 to the second port 108. In the third configuration, the lift valve assembly 116 is in the second open configuration, in which the main lift valve 160 engages the main seat portion 120 and the bleed lift valve 164 disengages from the bleed seat portion 166. In this manner, the main lift valve 160 blocks the flow between the first port 106 and the second port 108, while the bleed lift valve 164 allows flow from the control chamber 128 through the second orifice 162 of the main lift valve 160 (e.g., around the bleed lift valve 164 and through the bleed seat portion 166) to the second port 108. When the bleed lift valve 164 is away from the bleed seat portion 166, the pilot lift valve 140 can remain engaged with the pilot seat portion 142 to block the flow from the control chamber 128 through the third orifice 172 to the second port 108. For example, the preload on the pilot spring 140 can be used to move the pilot lift valve 140 to follow the movement of the bleed lift valve 164 such that the pilot lift valve 140 remains engaged with the pilot seat portion 142.

[0046] To place the valve 100 in the third configuration, the solenoid 144 can be de-energized so that the pilot spring 148 biases the pilot lift valve 140 into engagement with the pilot seat portion 142. This blocks the third orifice 172 to prevent fluid from flowing out of the control chamber 128 through this orifice. Similar to the first configuration, this forces the lift valve assembly into engagement with the main seat portion 120. Since the control chamber 128 remains connected to the first port 106 via the orifice 132, fluid will remain within the control chamber 128. The fluid within the control chamber 128 may increase in temperature (e.g., due to heat transfer from the surrounding environment), which may cause the fluid therein to expand. This thermal expansion will cause a corresponding increase in pressure within the control chamber 128. Since the main lift valve 160 engages the main seat portion 120 to block the first port 106 from the second port 108, and the pilot lift valve 140 engages the pilot seat portion 142 to block the third orifice 172, fluid cannot be drained along these paths to reduce the pressure within the control chamber 128. Thus, once the pressure differential between the control chamber 128 and the second port 108 reaches or exceeds the opening pressure such that the force acting on the first end 168 of the bleed lift valve 164 associated with the pressure within the control chamber 128 overcomes the force associated with the bleed spring 176 acting on the second end 170 of the bleed lift valve 164, the bleed lift valve 164 can disengage from the bleed seat portion 166. Accordingly, the bleed lift valve 164 can move within the second orifice 162 (e.g., along the axis 112), allowing fluid to flow through the bleed seat portion 166 and around the bleed lift valve 164 through the second orifice 162 to the second port 108. The movement of the bleed lift valve 164 compresses the bleed spring 176. Thus, once the pressure differential between the control chamber 128 and the second port 108 drops below the opening pressure, the force of the compressed bleed spring 176 again overcomes the force due to the pressure from the control chamber 128 to move the bleed lift valve 164 back into engagement with the bleed seat portion 166, thereby reverting to the first configuration.

[0047] Now refer to Figure 3, the bleed lift valve can be configured to provide threshold compensation, wherein the bleed lift valve can move a distance away from the bleed seat before opening the connection between the control chamber and the port. For example, the bleed lift valve 164 can include one or more notches 194 formed at the first end 168 of the bleed lift valve 164. The notch 194 can extend partially along the length of the bleed lift valve 164 from the first end 168 to the second end 170. Additionally, the bleed lift valve 164 and the second orifice 162 can be configured to provide a seal (e.g., a partial seal) at the notch 194 such that the bleed lift valve 164 can move a predetermined distance away from engagement with the bleed seat 166 before the notch 194 is exposed (e.g., uncovered) to allow flow from the control chamber 128 to the second port 108. Accordingly, the spring stiffness of the bleed spring 176 can be configured to combine with the dimensions (e.g., diameter) of the bleed lift valve 164 to provide a compensating movement.

[0048] Thus, as the pressure in the control chamber 128 increases (e.g., due to thermal expansion), but before reaching the opening pressure, the pressure in the control chamber 128 can act on the area of the notch 194 (e.g., the diameter of the bleed lift valve 164 at the notch 194 location) to cause the bleed lift valve 164 to start moving away from engagement with the bleed seat 166. During this initial movement, the notch 194 remains covered to block flow from the control chamber 128, although there may be some leakage due to manufacturing tolerances required to allow the bleed lift valve 164 to move in the second orifice 162. Additionally, this initial movement can unload some or all of the preload on the pilot spring 148. Unloading the pilot spring 148 can counteract the increased force that holds the pilot lift valve 140 against the pilot seat 142 due to the increased pressure in the control chamber 128. Then, once the opening pressure is reached, the bleed lift valve 164 further moves away from the bleed seat 166 to open the notch 194 and couple the control chamber 128 to the second port 108 to provide thermal bleed (e.g., in the third configuration), as generally discussed above.

[0049] In this specification, the embodiments have been described in a manner that enables a clear and precise description, but it is intended and will be understood that these embodiments can be variously combined or separated without departing from the invention. For example, it should be understood that all of the preferred features described herein can be applied to all aspects of the invention described herein.

[0050] Accordingly, while the invention has been described in connection with specific embodiments and examples, the invention is not necessarily so limited, and various other embodiments, examples, uses, modifications, and departures from the embodiments, examples, and uses are intended to be encompassed within the appended claims. The entire disclosure of each patent and publication cited herein is incorporated by reference as if each patent or publication was individually incorporated by reference herein.

[0051] The various features and advantages of the invention are set forth in the following claims.

Claims

1. A control valve, comprising: A valve body that defines a first bore, a first port and a second port in communication with the first bore, and a first seat portion between the first port and the second port; A first lift valve movably disposed within the first bore to selectively engage and disengage from the first seat portion, and defining a control chamber within the first bore opposite the second port, the first lift valve defining a second bore and a second seat portion and a third seat portion formed within the second bore, the second bore extending through the first lift valve to couple the control chamber to the second port; A second lift valve movably disposed within the second bore to selectively engage and disengage from the second seat portion, wherein the pressure within the control chamber biases the second lift valve to disengage from the second seat portion; And A first biasing member extending between the third seat portion and the second lift valve to bias the second lift valve to engage with the second seat portion.

2. The control valve according to claim 1, characterized in that The second lift valve defines a third bore extending through the second lift valve.

3. The control valve according to claim 2, wherein A check valve is further included, the check valve movably disposed within the third bore to selectively engage and disengage from a fourth seat portion formed within the third bore to allow fluid to flow from the control chamber to the second port.

4. The control valve according to claim 2 or 3, characterized in that, The first biasing member is configured to hold the check valve within the third bore.

5. The control valve according to any one of claims 1 to 4, characterized in that, A control passage extending between the control chamber and the first port is further included.

6. The control valve according to claim 5, characterized in that, The control passage is formed within the first lift valve.

7. The control valve according to any one of claims 1 to 6, characterized in that, When the first lift valve engages with the first seat portion, the second lift valve is configured to selectively disengage from the second seat portion based on the pressure difference between the control chamber and the second port to allow fluid to flow from the control chamber to the second port.

8. The control valve according to any one of claims 1 to 7, characterized in that, When the first lift valve disengages from the first seat portion, the second lift valve is configured to engage with the second seat portion to block fluid from flowing from the second port to the control chamber.

9. The control valve according to any one of claims 1 to 8, characterized in that, A second biasing member is further included, the second biasing member disposed within the first bore and configured to bias the first lift valve to engage with the first seat portion.

10. The control valve according to any one of claims 1 to 9, characterized in that, A third lift valve is further included, the third lift valve configured to selectively engage and disengage from a fifth seat portion defined by the second lift valve to selectively engage and disengage the first lift valve from the first seat portion, wherein when the third lift valve engages with the fifth seat portion, the third lift valve blocks fluid from flowing from the control chamber to the second port, such that the pressure difference between the control chamber and the second port biases the first lift valve to engage with the first seat portion, and wherein when the third lift valve disengages from the fifth seat portion, fluid flows from the control chamber to the second port, such that the pressure within the control chamber decreases, and the pressure difference between the control chamber and the second port biases the first lift valve to disengage from the first seat portion.

11. The control valve according to claim 10, wherein, It further includes an actuator configured to move the third lift valve to selectively engage and disengage the third lift valve with the fifth seat portion.

12. The control valve according to claim 11, characterized in that, It further includes a third biasing member configured to bias the third lift valve into engagement with the fifth seat portion, wherein the actuator is configured to compress the third biasing member to disengage the third lift valve from the fifth seat portion.

13. The control valve according to claim 12, wherein, The actuator is configured as a solenoid including an armature and a coil, wherein energization of the coil causes the armature to move to compress the third biasing member.

14. The control valve according to claim 13, wherein The third biasing member extends between the body of the solenoid and the third lift valve, and wherein the third lift valve extends through the armature.

15. A control valve, comprising: a valve body defining a first port and a second port in communication with a first hole; a main lift valve movably disposed in the first hole to selectively couple the first port and the second port, and defining a control chamber in the first hole opposite to the second port and in fluid communication with the first port, the main lift valve defining a second hole extending through the main lift valve to allow fluid to flow from the control chamber to the second port; a bleed lift valve movably disposed in the second hole to selectively couple the control chamber to the second port via the second hole, the bleed lift valve defining a third hole extending through the main lift valve to allow fluid to flow from the control chamber to the second port; and a pilot lift valve movably disposed in the first hole to selectively couple the control chamber to the second port via the third hole.

16. The control valve according to claim 15, wherein, It further includes a check valve disposed in the bleed lift valve to block fluid from flowing from the second port to the control chamber.

17. The control valve according to claim 15 or 16, characterized in that, The main lift valve is configured to couple the first port to the second port based on at least one of the following: a first pressure difference between the control chamber and the second port to allow fluid to flow from the first port to the second port; and a second pressure difference between the first port and the second port to allow fluid to flow from the second port to the first port.

18. The control valve according to any one of claims 15 to 17, characterized in that The bleed lift valve is configured to couple the control chamber to the second port via the second hole based on the pressure difference between the control chamber and the second port when the first port is blocked from the second port by the main lift valve.

19. The control valve according to any one of claims 15 to 18, characterized in that, When the pilot lift valve moves to couple the control chamber to the second port via the third hole, the pressure difference between the control chamber and the second port causes the main lift valve to move to couple the first port to the second port.

20. The control valve according to any one of claims 15 to 19, characterized in that, It further includes an actuator configured to move the pilot lift valve to selectively couple the control chamber to the second port via the third hole.

21. The control valve according to any one of claims 15 to 20, characterized in that, It further includes: A first biasing member configured to bias the main lift valve to block the first port from the second port; A second biasing member configured to bias the bleed lift valve to block the control chamber from the second port; And A third biasing member configured to bias the pilot lift valve to block the control chamber from the second port.

22. The control valve according to claim 21, wherein, The first biasing member is held in the control chamber, and the second biasing member is held in the second bore.

23. A control valve, comprising: A valve body defining a first bore, a first port and a second port in communication with the first bore, and a main seat between the first port and the second port; A lift valve assembly movably disposed within the first bore, the lift valve assembly including a first end, a second end, and a passage, the first end configured to engage the main seat to selectively couple the first port and the second port, the second end configured to define a control chamber within the first bore opposite the second port, the passage extending between the first end and the second end, wherein a pilot seat is formed on the second end between the control chamber and the passage; and a pilot lift valve movably disposed within the control chamber and configured to engage the pilot seat to selectively couple the control chamber to the second port via the passage; and Wherein the lift valve assembly includes: A main lift valve configured to engage the main seat and defining a second bore forming the passage and a bleed seat within the second bore; and A bleed lift valve movably disposed within the second bore to selectively engage the pilot seat, the bleed lift valve defining the pilot seat and a third bore forming the passage.

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