System and method for hydraulic machine steering control

Abstract

A control valve for a hydraulic machine steering system includes a valve body defining a first actuator port, a second actuator port, a tank port, a pump port, and a manual steering interface. A directional control spool is disposed within the valve body to selectively couple the first actuator port, the second actuator port, the tank port, and the pump port. Further, an isolation spool is disposed within the valve body to selectively couple the directional control spool to each of the first actuator port, the second actuator port, and the pump port, and to selectively couple the pump port to the manual steering interface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 409,614, filed on September 23, 2022, which is incorporated herein by reference in its entirety. Background Art

[0002] The steering system can be used to control the direction of travel of the hydraulic machine. The steering system can include a steering control valve configured to control the flow of hydraulic fluid of an actuator to adjust the steering direction. Such a steering control valve can include a manual steering valve configured to control the steering direction based on an operator input and an electronic steering valve configured to control the steering direction based on an electronic signal such as a remote control, autonomous control or other electronic control for the hydraulic machine. Summary of the invention

[0003] The steering system as described herein can allow manual and electronic control of a hydraulic machine. In general, the steering system can include an electronic steering valve (e.g., a first valve section) configured to be coupled to a manual steering valve (e.g., a second valve section). The electro-hydraulic steering valve can include an isolation spool that can switch the steering system between a manual steering mode and an electronic steering mode.

[0004] According to one aspect of the present disclosure, a control valve for a hydraulic machine steering system may include a valve body that defines a first actuator port, a second actuator port, a tank port, a pump port, and a manual steering interface. A directional control valve core may be disposed in the valve body to selectively couple the first actuator port, the second actuator port, the tank port, and the pump port. In addition, an isolation valve core may be disposed in the valve body to selectively couple the directional control valve core to each of the first actuator port, the second actuator port, and the pump port, and to selectively couple the pump port to the manual steering interface.

[0005] In some non-limiting examples, the directional control valve core can be configured to move between each of a first directional position, a second directional position, and a third directional position. In the first directional position, the directional control valve core can be configured to couple each of the first actuator port and the second actuator port to the reservoir port. In the second directional position, the directional control valve core can be configured to couple the pump port to the first actuator port and the second actuator port to the reservoir port. In the third directional position, the directional control valve core can be configured to couple the pump port to the second actuator port and the first actuator port to the reservoir port. In some cases, the control valve may include a biasing assembly configured to bias the directional control valve core to the first directional position. The biasing assembly may include a first directional control spring and a second directional control spring, which may be in opposite configurations around the directional control valve core to bias the directional control valve core to the first directional position.

[0006] In some non-limiting examples, the control valve may further include a first electronically controlled pressure regulating valve and a second electronically controlled pressure regulating valve. The first electronically controlled pressure regulating valve may be configured to move the directional control valve core from a first directional position to a second directional position. The second electronically controlled pressure regulating valve may be configured to move the directional control valve core from the first directional position to a third directional position. In some cases, each of the first electronically controlled pressure regulating valve and the second electronically controlled pressure regulating valve may be movable between a first position and a second position, the first position coupling a corresponding pilot pressure connection of the directional control valve core to a tank port, and the second position coupling the corresponding pilot pressure connection to a pump port.

[0007] In some non-limiting examples, the isolation valve core can be configured to move between each of a first isolation position, a second isolation position, and a third isolation position. In the first isolation position, the isolation valve core can be configured to block the first actuator port and the second actuator port from the directional control valve core, and connect the pump port to the manual steering interface. In the second isolation position, the isolation valve core can be configured to block the manual steering interface from the pump port, and connect the directional control valve core to each of the first actuator port, the second actuator port, and the pump port. In the third isolation position, the isolation valve core can be configured to connect the pump port to the manual steering interface, and connect the directional control valve core to each of the first actuator port, the second actuator port, and the pump port. In some cases, the control valve may also include a first isolation spring configured to bias the isolation valve core to the first isolation position. In some cases, the control valve may also include a second isolation spring arranged in series with the first isolation spring to bias the isolation valve core to the first isolation position.

[0008] In some non-limiting examples, the pressure connection of the isolator valve core can be connected to the pump port, and the control valve can also include an enabling solenoid to selectively connect the pressure connection to the tank port to control the movement of the isolation valve core. In some cases, the pressure connection can be a first pressure connection, and the control valve can also include a second pressure connection of the isolation valve core arranged opposite to the first pressure connection. The throttle hole can be positioned between the pump port and the pressure connection. The enabling solenoid can be configured as one of a switch solenoid and a proportional solenoid. The enabling solenoid can operate between each of the disabled position and the enabled position. In the disabled position, the enabling solenoid can be configured to connect the pressure connection to the tank port so that the isolation valve core is biased to the first isolation position. In the enabled position, the enabling solenoid can be configured to block the pressure connection from the tank port so that the pressure at the pump port moves the isolation valve core from the first isolation position toward the second isolation position. In some cases, when the enable solenoid is in the enabled position, the position of the isolation spool may be continuously variable between the second isolation position and the third isolation position based on the pressure at the pressure connection.

[0009] In some non-limiting examples, the manual steering interface may be configured to couple with a manual steering valve and may include a pump connection, a tank connection, a first actuator connection, and a second actuator connection.

[0010] According to another aspect of the present disclosure, a steering system for a hydraulic machine is provided, the hydraulic machine having a pump, an actuator and a reservoir. The steering system may include a manual steering valve, the manual steering valve including a first pump connection, a first reservoir connection, a first actuator connection, and a second actuator connection. The manual steering valve may be configured to selectively couple the first pump connection, the first reservoir connection, the first actuator connection, and the second actuator connection. The steering system may also include an electronic steering valve. The electronic steering valve may include a valve body, the valve body defining: a pump port configured to be coupled to a pump, a first actuator port configured to be coupled to an actuator, a second actuator port configured to be coupled to an actuator, a reservoir port configured to be coupled to a reservoir, a second pump connection configured to be coupled to a first pump connection, a second reservoir connection configured to be coupled to a first reservoir connection, a third actuator connection configured to be coupled to a first actuator connection, and a fourth actuator connection configured to be coupled to a second actuator connection. A directional control valve core may be disposed in the valve body. The directional control spool may be configured to selectively couple the pump port, the first actuator port, the second actuator port, and the tank port. In addition, an isolation spool may be disposed in the valve body. The isolation spool may be configured to switch the steering system between a manual steering mode and an electronic steering mode. In the manual steering mode, the directional control spool may be decoupled from the pump port, the first actuator port, and the second actuator port through the isolation spool. In the electronic steering mode, the directional control spool may be coupled to the pump port, the first actuator port, and the second actuator port through the isolation spool.

[0011] In some non-limiting examples, the third actuator connection can be directly connected to the first actuator port, and the fourth actuator connection can be directly connected to the second actuator port. In the manual steering mode, the isolation valve core can be in a first isolation position, which blocks the first actuator port and the second actuator port from the directional control valve core and connects the pump port to the manual steering valve. In the electronic steering mode, the isolation valve core can move between each of the second isolation position and the third isolation position. In the second isolation position, the isolation valve core can be configured to block the manual steering valve from the pump port and connect the directional control valve core to each of the first actuator port, the second actuator port and the pump port. In the third isolation position, the isolation valve core can be configured to connect the pump port to the manual steering valve and connect the directional control valve core to each of the first actuator port, the second actuator port and the pump port.

[0012] In some non-limiting examples, the steering system may further include an electronic controller configured to move the isolation valve core to switch between the manual steering mode and the electronic steering mode. The electronic controller may be configured to operate an enabling solenoid. The enabling solenoid may be configured to selectively connect the pressure connection of the isolation valve core to the tank port so that the steering system is in the manual steering mode, and to disconnect the pressure connection from the tank port so that the steering system is in the electronic steering mode. In the electronic steering mode, the electronic controller may be configured to operate the first electronically controlled pressure regulating valve and the second electronically controlled pressure regulating valve to move the directional control valve core between each of the first directional position, the second directional position, and the third directional position. In the first directional position, the directional control valve core may be configured to connect each of the first actuator port and the second actuator port to the tank port. In the second directional position, the directional control valve core may be configured to connect the pump port to the first actuator port and the second actuator port to the tank port. In the third directional position, the directional control spool may be configured to couple the pump port to the second actuator port and to couple the first actuator port to the tank port.

[0013] In some non-limiting examples, the actuator may include a first actuator and a second actuator. The first actuator may be coupled to the first actuator port, and the second actuator may be coupled to the second actuator port.

[0014] The present disclosure will be better understood, and its features, aspects and advantages will become apparent, when considering the following detailed description.This detailed description refers to the following drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of a steering system according to aspects of the present disclosure.

[0016] Figure 2 yes Figure 1 Detailed schematic diagram of a non-limiting example of an electronic steering valve for a steering system.

[0017] Figure 3 yes Figure 2 A partial cross-sectional view of an electronic steering valve with the isolation valve core in a first position.

[0018] Figure 4 yes Figure 2 A partial cross-sectional view of an electronic steering valve with the isolation valve core in a second position.

[0019] Figure 5 yes Figure 2 A partial cross-sectional view of an electronic steering valve with the isolation valve core in the third position.

[0020] Figure 6 yes Figure 1 Detailed schematic diagram of another non-limiting example of an electronic steering valve for a steering system.

[0021] Figure 7 yes Figure 6 A partial cross-sectional view of an electronic steering valve with the isolation valve core in a first position.

[0022] Figure 8 yes Figure 6 A partial cross-sectional view of an electronic steering valve with the isolation valve core in a second position.

[0023] Fig. 9 yes Figure 6 A partial cross-sectional view of an electronic steering valve with the isolation valve core in the third position. DETAILED DESCRIPTION

[0024] 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 the components set forth in the following description or shown in the accompanying drawings. The present disclosure is capable of other constructions and can be practiced or implemented in various ways. Moreover, it should be understood that the words and terms used herein are for descriptive purposes and should not be considered as limiting. "Including," "including," or "having" and variations thereof used herein are intended to cover the items listed thereafter and their equivalents and additional items. Unless otherwise specified or limited, the terms "mounting," "connecting," "supporting," and "coupling" and variations thereof are used in a broad sense and cover direct and indirect mounting, connection, supporting, and coupling. Further, "connecting" and "coupling" are not limited to physical or mechanical connections or couplings, and may also indicate fluid couplings.

[0025] As used herein, unless otherwise defined or limited, for ease of reference, ordinal numbers used herein are generally based on the order in which specific components are presented for relevant portions of the present disclosure. In this regard, for example, names such as "first," "second," and the like generally indicate only the order in which relevant components are introduced for discussion, and generally do not indicate or require a particular spatial arrangement, functional or structural priority or order.

[0026] The following discussion is proposed to enable those skilled in the art to make and use various aspects of the present disclosure. Various modifications to the described construction will be apparent to those skilled in the art, and the general principles herein may be applied to other constructions and applications without departing from various aspects of the present disclosure. Therefore, various aspects of the present disclosure are not intended to be limited to the construction shown, but are given the widest scope consistent with the principles and features disclosed herein. The following specific embodiments should be read with reference to the accompanying drawings, in which the same elements in different drawings have the same reference numerals. The accompanying drawings are not necessarily drawn to scale, and they 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.

[0027] As described above, a hydraulic machine (e.g., an off-highway machine such as a tractor, forklift, backhoe, wheel loader, excavator, etc.) may include a steering system to control the direction of travel of the hydraulic machine. Conventional hydraulic machines may be equipped with a manual steering function and may include a conventional manual steering valve configured to control an actuator in response to a manual input by an operator to adjust the steering direction of the hydraulic machine. In some cases, the hydraulic machine may also be equipped with an electronic steering valve that may be used in conjunction with an external sensor to allow remote steering, autonomous steering, or semi-autonomous steering capabilities.

[0028] Typically, in the case of providing both manual and electronic steering control, the steering system includes a manual steering device and an electronic steering device. In order to switch between the manual steering mode and the electronic steering mode, the conventional system typically includes: a separate pump isolation device that determines which steering system (e.g., manual or electronic) is active; and a separate work port blocking circuit that isolates the manual steering valve from the electronic steering valve (e.g., by isolating the directional control element of the electronic steering valve from the actuator). If the steering system includes a fixed displacement pump to provide the required fluid flow, a separate unloading device may also be required to allow excess flow (e.g., flow not consumed by the actuator) to be discharged to a tank. These separate components are required to allow both manual steering and electric steering, which increases the cost and complexity of the system and may also increase the overall size of the system.

[0029] A steering system according to the present disclosure can provide improvements to conventional designs by integrating a pump isolation device, a workport blocking circuit, and an unloading device into a single logic element (e.g., a flow control element, such as a sliding valve) within an electronic steering valve. For example, a steering system may include a manual steering valve connected to a pump, a tank, and an actuator via an electronic steering valve. The flow control element may be movably disposed within a housing of the electronic steering valve to switch the steering system between a manual steering mode and an electronic steering mode (e.g., an autonomous or semi-electronic steering mode). Movement of the flow control element (i.e., a first flow control element) within the housing can selectively connect the pump, the actuator, and the tank to a second flow control element and a manual steering valve of an electronic steering valve configured to direct fluid to one or more actuators to adjust the steering angle.

[0030] In some cases, switching between the manual steering mode and the electronic steering mode can be controlled by operating an enabling solenoid. The enabling solenoid can be moved between a disabled position, which moves the first flow control element to a first position that allows manual control and isolates the second flow control element from the pump and the actuator, and an enabled position that couples the pump and the actuator to the second flow control element. When excess flow is provided, the first flow control element can be configured to discharge the excess flow to a tank through the manual steering valve.

[0031] Reference Figure 1 , the hydraulic vehicle may include a steering system 100 to provide directional control of the hydraulic vehicle. The steering system 100 includes an actuator 104, which can control the steering direction of the hydraulic vehicle. For example, the actuator 104 can operate (e.g., extend or retract) to control the angle of the wheel of the hydraulic machine. Depending on the specific embodiment, the actuator 104 can be a single actuator (e.g., a double-acting hydraulic actuator) or multiple actuators (e.g., a first single-acting hydraulic actuator and a second single-acting hydraulic actuator). Accordingly, a pump 108 (e.g., a variable displacement pump or a constant displacement pump) can be provided to supply a flow of hydraulic fluid to the actuator 104, and a storage tank 112 can be provided to allow fluid discharge from the actuator 104.

[0032] To control the operation of the actuator 104, the steering system 100 may include a control valve 102 (e.g., a steering control valve) configured to selectively couple the actuator 104 to the pump 108 and the reservoir 112. The control valve 102 may be configured to allow both manual control of the steering system 100 and electronic control of the steering system (e.g., autonomous control or semi-autonomous control). To allow manual control, the steering system 100 may include a manual steering valve 124 (e.g., a first control valve). Generally, the manual steering valve 124 may include a valve body 126 configured to house a control element to operate the actuator 104 by directing fluid between the pump 108, the actuator 104, and the reservoir 112. Accordingly, as will be described in more detail below, the valve body 126 can define: a pump connection 128 (e.g., a first pump connection) configured to receive fluid flow from the pump 108, a tank connection 132 (e.g., a second pump connection) configured to discharge fluid to the tank 112, and a first working port connection 136 (e.g., a first actuator connection) and a second working port connection 144 (e.g., a second actuator connection) configured to allow fluid to flow between the actuator 104 and the manual steering valve 124.

[0033] The manual steering valve 124 can be any type of conventional steering valve, such as an orbitrol valve or a directional control valve. The manual steering valve 124 can be configured to operate the actuator 104 in a manual steering mode in response to an operator input. In some cases, the manual steering valve 124 can be physically connected to a manual input device 106 (e.g., a steering wheel, a joystick, a foot pedal, etc.) on which the operator provides steering input. Relatedly, the manual input device 106 can be mounted on a hydraulic press. In addition, the manual control interface can be configured to allow the operator to switch from a manual steering mode to an electronic steering mode (e.g., via a button or switch), and vice versa.

[0034] To allow for electronic control, the steering system 100 may also include an electronic steering valve 116 (e.g., a second control valve). The electronic steering valve 116 may be a single control valve (e.g., a single valve block or valve section) that may be mounted on a hydraulic machine, as compared to conventional designs that provide multiple valve blocks to control, for example, electronic control activation and electronic control steering. As will become apparent in the following discussion, providing the electronic steering valve 116 as a single valve block may achieve a number of advantages over conventional systems, including, for example, improved operating efficiency, and reduced need for separate controllers and external plumbing to connect and operate the electronic steering valve 116 with various machine functions. Use of a single valve block may further reduce the space occupied by the electronic steering valve 116, thereby allowing for improved packaging.

[0035] The electronic steering valve 116 can be coupled to the controller 120. As discussed further below, the electronic steering valve 116 can receive commands from the controller 120 to operate the actuator 104 in the electronic steering mode and switch the steering system 100 between the electronic steering mode and the manual steering mode. In some cases, the controller 120 can receive an input corresponding to the steering angle of the steering system 100 from a sensor 122 (e.g., a wheel angle sensor). The controller 120 can control the electronic steering valve 116 based on the signal from the sensor 122, thereby controlling the actuator 104 so that the steering system 100 moves between the current steering angle and the desired steering angle. In addition, the controller 120 can communicate with the manual input device 106. Therefore, as described above, the operator can control the steering mode of the steering system 100. Alternatively, the controller 120 can be configured to automatically switch between the steering modes. For example, the controller 120 can be configured to automatically switch to the manual steering mode once a manual input is received when in the electronic steering mode. As another example, the controller 120 may be configured to automatically switch from the manual steering mode to the electronic steering mode upon reaching a particular work area or completing a work task.

[0036] Additional references Figure 2 , the electronic steering valve 116 can be positioned between each of the pump 108, the actuator 104 and the tank 112 and the manual steering valve 124. In this way, the drive mode of the steering system 100 can be set by controlling the electronic steering valve 116. It should be understood that the electronic steering valve 116 can be directly or indirectly connected to the manual steering valve 124 (for example, via a pipeline). For example, the electronic steering valve 116 and the manual steering valve 124 can be configured to be connected together to form a valve section of the main valve. In other cases, they can be separate valves that are configured to be directly or indirectly connected to each other, such as for use as a conversion kit application. Therefore, the manual steering valve 124 and the electronic steering valve 116 can be installed at the same position or different positions on the hydraulic press.

[0037] The electronic steering valve 116 can include a valve body 148 that defines a pump port 152 configured to be coupled to the pump 108, a tank port 156 configured to be coupled to the tank 112, a first workport 160 (e.g., a first actuator port), and a second workport 164 (e.g., a second actuator port). Fluid can flow between the actuator 104 and each of the first workport 160 or the second workport 164 to steer the hydraulic vehicle (e.g., to the right or to the left). It should be understood that the valve body 148 can define various internal passages to allow fluid to flow between various ports, connections, and components, as described herein.

[0038] In the non-limiting example shown, the actuator 104 is configured as an actuator system including a first actuator 140 and a second actuator 142 (collectively referred to as the actuator 104). The first workport 160 is configured to be coupled to the first actuator 140, and the second workport 164 is configured to be coupled to the second actuator 142. To divert in a first direction, the fluid may flow from the pump 108 to the first actuator 140 via the first workport 160, and from the second actuator 142 to the reservoir 112 via the second workport 164. To divert in an opposite second direction, the fluid may flow from the pump 108 to the second actuator 142 via the second workport 164, and from the first actuator 140 to the reservoir 112 via the first workport 160. In other non-limiting examples, particularly those with a single, double-acting actuator, the workports may be coupled to opposite sides of the actuator.

[0039] To couple to the manual steering valve 124, the valve body 148 may further define a manual steering interface 168 configured to couple to the manual steering valve 124. The manual steering interface 168 may include a pump connection 170 (e.g., a second pump connection) configured to couple to the pump connection 128 of the manual steering valve 124, a tank connection 172 (e.g., a second tank connection) configured to couple to the tank connection 132 of the manual steering valve 124, a first workport connection 174 (e.g., a third workport or actuator connection) configured to couple to the first workport connection 136 of the manual steering valve 124, and a second workport connection 176 (e.g., a fourth workport or actuator connection) configured to couple to the second workport connection 144 of the manual steering valve 124. The reservoir connection 172 may be coupled to the reservoir port 156 , the first workport connection 174 may be coupled to the first workport 160 , and the second workport connection 176 may be coupled to the second workport 164 to allow direct fluid communication therebetween.

[0040] However, as will be described in more detail below, a control element may be provided between the pump port 152 and the pump connection 170 to selectively isolate the flow of the pump 108 to the manual steering valve 124 to control the steering mode. That is, the pump flow will be isolated to flow to the manual steering valve 124, rather than providing flow to another control element of the electronic steering valve 116 for use according to the operator's input. For example, the control element may couple the pump port 152 and the pump connection 170 in the manual steering mode so that the flow of the pump 108 is distributed to the actuator 104 (e.g., the first actuator 140 and the second actuator 142) through the manual steering valve 124 according to the operator's input. However, in the electronic steering mode, the control element may selectively isolate the pump port 152 from the pump connection 170 to allow the electronic steering valve 116 to control the actuator 104 via a command from the controller 120.

[0041] To control steering in the electronic steering mode, the electronic steering valve 116 may be configured to selectively couple the actuators 104 (e.g., the first actuator 140 and the second actuator 142) to the pump 108 and the reservoir 112. More specifically, the electronic steering valve 116 may include a flow control element configured to selectively couple the pump port 152, the reservoir port 156, the first workport 160, and the second workport 164. In the non-limiting example shown, the electronic steering valve 116 includes a directional control spool 184 that may be movably disposed within the valve body 148 to move between a plurality of positions (e.g., directional positions) to control fluid flow to the actuator 104 and, therefore, control the steering direction of the steering system 100. Movement of the directional control spool 184 may allow fluid to flow into, out of, or between one or more passages formed within the valve body 148 to achieve a desired steering direction. In the non-limiting example shown, the directional control spool 184 is configured to move between three directional positions. The directional control spool 184 may be configured to move discretely or continuously variably between these positions.

[0042] The first directional position can be used when no steering input is needed, such as when the hydraulic machine moves back and forth substantially straight, or when the electronic steering is disabled. The first directional position can be configured to couple each of the first workport 160 and the second workport 164 to the tank port 156, and to block the first workport 160 and the second workport 164 from the pump port 152. Thus, when the directional control spool 184 is coupled to the first workport 160 and the second workport 164, the first actuator 140 and the second actuator 142 can discharge to the tank 112, as long as these connections are not blocked, as described below. In some cases, a spring biased check valve 166 can be positioned between the tank port 156 and the directional control spool 184 to maintain the actuator 104 at a predetermined minimum pressure, or to prevent fluid from flowing back from the tank 112 to the actuator 104.

[0043] The second directional position and the third directional position can be used to selectively operate the first actuator 140 and the second actuator 142 to change the steering direction. Specifically, the second directional position can be configured to couple the first working port 160 to the pump port 152 to supply fluid to the first actuator 140 (e.g., to extend the first actuator 140), and couple the second working port 164 to the tank port 156 to discharge fluid from the second actuator 142 to the tank 112 (e.g., to retract the second actuator 142). Therefore, the second directional position can steer the steering system 100 in the first direction. Conversely, the third directional position can be configured to couple the second working port 164 to the pump port 152 to supply fluid to the second actuator 142 (e.g., to extend the second actuator 142), and couple the first working port 160 to the tank port 156 to discharge fluid from the first actuator 140 to the tank 112 (e.g., to retract the first actuator 140). Thus, the third directional position may cause the steering system 100 to steer in a second direction opposite to the first direction.

[0044] In some cases, in order to prevent over-pressurization of the first actuator 140 and the second actuator 142 in the second directional position and the third directional position, a pressure relief valve 158 may be provided between the directional control valve spool 184 and the tank port 156. The first actuator 140 and the second actuator 142 may be coupled to the pressure relief valve 158 via the directional control valve spool 184. In some cases, a throttle orifice 288 may be positioned between the pressure relief valve 158 and the directional control valve spool 184. In the event that the pressure in the active working port exceeds the setting value of the pressure relief valve 158, the throttle orifice 288 may limit the flow out of the pressure relief valve 158.

[0045] To provide electronic steering, the directional control spool 184 may be configured to be moved between directional control positions by the controller 120. For example, still referring to Figure 2 , the directional control valve core 184 can be configured as a spring-biased directional control valve core, which includes a biasing assembly 192 to bias the directional control valve core 184 to a first directional position. The biasing assembly 192 includes a first compliance member 196 (e.g., a first directional control spring or other type of elastic member) arranged on a first side of the directional control valve core 184 and a second compliance member 204 (e.g., a second control spring or other type of elastic member) arranged on a second side of the directional control valve core 184. Therefore, the first compliance member 196 and the second compliance member 204 are in an opposite configuration around the directional control valve core 184. The first compliance member 196 and the second compliance member 204 can be provided with an initial preload compression to bias the directional control valve core 184 to the first directional position. In some examples, the first compliance member 196 and the second compliance member 204 can be provided with substantially similar preload compressions. In some examples, a single spring can be used and arranged to bias the directional control valve core 184 to the first directional control position.

[0046] To move the directional control spool 184 from the first directional position toward each of the second directional position and the third directional position, the electronic steering valve 116 may include one or more electronically controlled pressure regulating valves (EPRVs), or another type of electric hydraulic control element (e.g., a solenoid). In the non-limiting example shown, the electronic steering valve 116 includes a first EPRV 212 and a second EPRV 216. The first EPRV is coupled between the pump port 152 and a first pilot pressure connection 220 of the directional control spool 184, which is disposed on a second side of the directional control spool 184, opposite the first compliance member 196. Correspondingly, the second EPRV 216 is coupled between the pump port 152 and a second pilot pressure connection 222 of the directional control spool 184, which is disposed on a first side of the directional control spool 184, opposite the second compliance member 204.

[0047] Each of the first EPRV 212 and the second EPRV 216 can be operated (e.g., energized) by the controller 120 to move from a first position (e.g., a first steering position) configured to couple the corresponding pilot pressure connection to the tank 112 (e.g., the tank port 156) to release pressure and a second position (e.g., a second steering position) configured to couple the corresponding pilot pressure connection to the pump 108 (e.g., the pump port 152) to increase pressure. The first EPRV 212 and the second EPRV 216 are biased to the first position. Therefore, with the first EPRV 212 and the second EPRV 216 deactivated, both the first pilot pressure connection 220 and the second pilot pressure connection 222 are connected to the tank 112, and the directional control spool 184 is biased to the first directional position by the compliance members 196, 204. Activating the first EPRV 212 will increase the pressure at the first pilot pressure connection 220, causing the first compliance member 196 to compress and move the directional control spool 184 to the second directional position. Activating the second EPRV 216 will increase the pressure at the second pilot pressure connection 222, causing the second compliance member 204 to compress and move the directional control spool 184 to the third directional position. It should be understood that only one EPRV can be activated at a time.

[0048] Additional references Figure 3-Figure 5In order to control the steering mode of the steering system 100, the electronic steering valve 116 may further include an isolation spool 224 (e.g., a flow control element). The isolation spool 224 may be movably disposed within the valve body 148 to switch between the manual steering mode and the electronic steering mode (i.e., to activate and deactivate the electronic steering). More specifically, the isolation spool 224 is configured to move to selectively couple the directional control spool 184 to each of the first working port 160, the second working port 164, and the pump port 152, and to selectively couple the pump port 152 to the manual steering interface 168 (e.g., at the pump connection 170). Thus, the isolation spool 224 may selectively activate and deactivate the electronic steering mode of the hydraulic vehicle. To activate the electronic steering mode, the isolation spool 224 may couple the directional control spool 184 to each of the first working port 160, the second working port 164, and the pump port 152. To deactivate the electronic steering mode (i.e., activate the manual steering mode), the isolation spool 224 may couple the pump port 152 to the manual steering interface 168 and decouple the directional control spool 184 from each of the first workport 160, the second workport 164, and the pump port 152. The coupling of the pump port 152 to the manual steering interface 168 may allow fluid to bypass the directional control spool 184 to flow into and operate the manual steering valve 124. In other words, in the manual steering mode, the isolation spool 224 may be configured to isolate the directional control spool 184 from the manual steering valve 124 to ensure that the operator can maintain control of the steering system 100 even if the directional control spool 184 moves toward the second directional position or the third directional position.

[0049] To switch between the steering modes, the isolation spool 224 can be movable between a plurality of positions (i.e., isolation positions). Movement of the isolation spool 224 between the various positions can control the flow of fluid into, out of, or between one or more passages formed in the valve body 148 to couple and decouple the various ports as described above. In the non-limiting example shown, the isolation spool 224 is configured to move between three isolation positions.

[0050] In a first isolated position (see e.g. Figure 3), the isolation spool 224 is configured to place the steering system 100 in the manual steering mode by isolating the directional control spool 184 from the manual steering valve 124 and the actuators 104 (e.g., the first actuator 140 and the second actuator 142). More specifically, in the first isolation position, the isolation spool 224 is configured to block the connection (e.g., passage) between each of the first workport 160 and the second workport 164 and the isolation spool 224 and the corresponding passages 280, 282 (e.g., the first and second passages) that allow fluid to flow into and out of the actuator 104 to pass between the directional control spool 184 and the isolation spool 224. Therefore, the isolation spool 224 blocks and isolates each of the first workport 160 and the second workport 164 from the directional control spool 184. In addition, the isolation spool 224 is configured to block the third passage 284, which allows fluid from the pump 108 to flow from the isolation spool 224 to the directional control spool 184, where it can then be distributed to the actuator 104 via passages 280, 282. In addition, in the first isolation position, the isolation spool 224 is also configured to couple the pump port 152 to the pump connection 170 to allow flow from the pump 108 to be supplied to the manual steering valve 124. Therefore, the manual steering valve 124 can then direct flow from the pump 108 to the actuator 104 by selectively coupling the pump connection 170, the tank connection 172, the first workport connection 174, and the second workport connection 176 according to the operator input at the manual input device 106.

[0051] In the second isolation position (see e.g. Figure 4 ) and a third isolation position (see e.g. Figure 5 ), the isolation spool 224 is configured to place the steering system 100 in the electronic steering mode by coupling the directional control spool 184 with the pump 108, the actuator 104, and the reservoir 112. More specifically, in both the second isolation position and the third isolation position, the isolation spool 224 couples the first workport 160 to the directional control spool 184 via the first passage 280, couples the second workport 164 to the directional control spool 184 via the second passage 282, and couples the pump port 152 to the directional control spool 184 via the third passage 284. Thus, as described above, the pump 108 can supply fluid to operate the actuator 104 depending on the position of the directional control spool 184. Correspondingly, fluid flow from the actuator 104 (e.g., from the retraction of the first actuator 140 or the second actuator 142) can be discharged to the reservoir 112 via the directional control spool 184 (e.g., through the spring-biased check valve 166).

[0052] However, in the second isolation position, the isolation spool 224 is configured to block the pump port 152 from the pump connection 170 (e.g., the manual steering valve 124), and in the third isolation position, the isolation spool 224 is configured to couple the pump port 152 to the pump connection 170 (e.g., the manual steering valve 124). Thus, the second isolation position may be a blocking position that allows all pump flow to be supplied to the actuator 104, and the third isolation position may be an unloading position that allows excess pump flow to be discharged to the tank 112 via the manual steering valve 124. That is, in the third isolation position, the manual steering valve 124 may be in a neutral or bypass mode that is configured to allow flow supplied at the pump connection 170 to be discharged directly to the tank 112 through the tank connection 172. For example, the control element of the manual steering valve 124 may couple the pump connection 128 to the tank connection 132 while blocking the first workport connection 136 and the second workport connection 144. As explained in greater detail below, the isolation spool 224 may be continuously variably positioned between the second isolation position and the third isolation position based on the demands of the actuator 104 (eg, the position of the directional control spool 184 ).

[0053] Still refer to Figure 2-Figure 5 , the isolation valve core 224 can be biased to the first isolation position and moved to the second isolation position or the third isolation position according to a command from the controller 120. Therefore, the isolation valve core 224 may include a biasing assembly 228 (e.g., an isolation biasing assembly) configured to bias the isolation valve core 224 to the first isolation position. More specifically, the biasing assembly 228 may include one or more compliance members. In the non-limiting example shown, the biasing assembly 228 is positioned at the first end of the isolation valve core 224 and includes a first compliance member 232 (e.g., a first isolation spring or other type of elastic member) and a second compliance member 236 (e.g., a second isolation spring or other type of elastic member) arranged in series with each other. The first compliance member 232 and / or the second compliance member 236 can be provided with an initial preload compression so as to bias the isolation valve core 224 to the first isolation position. The second compliance member 236 extends between and is retained in the first seat 240 and the second seat 244. The first seat 240 can be a fixed seat, in which case it is formed by the valve body 148 (e.g., a cover fixed to the valve body 148). The second seat 244 can be configured as a floating seat movably disposed within the valve body 148. The first compliance member 232 extends between and is retained in the second seat 244 and a third seat 248 defined by the isolation valve core 224. In other non-limiting examples, the first compliance member and the second compliance member can be arranged differently. For example, first compliant member 232 may extend between first seat 240 and second seat 244 and be retained therebetween, and second compliant member 236 may extend between second seat 244 and third seat 248 and be retained therebetween.

[0054] The first compliance member 232 and the second compliance member 236 can be compressed between the first seat 240 and the third seat 248 to allow the isolation valve core 224 to move from the first isolation position through the second isolation position to the third isolation position. In some configurations, the first compliance member 232 can be configured to be fully compressed before the second compliance member 236 begins to compress. For example, in some configurations, the second compliance member 236 can have sufficient initial pre-compression (e.g., initial preload) so that the first compliance member 232 will be compressed first. In this way, the first compliance member 232 can be selectively compressed to move the isolation valve core 224 between the first isolation position and the second isolation position, thereby switching the steering system between the manual steering mode and the electronic steering mode. Correspondingly, in the electronic steering mode, the second compliance member 236 can be selectively compressed to change the position of the isolation valve core 224 to any position between the second isolation position and the third isolation position. In other words, second compliance member 236 is configured to adjust to maintain a boundary pressure between the first and second ends of isolation valve spool 224 as system pressure and flow demands change, which changes the position of isolation valve spool 224 .

[0055] The position of the isolation spool 224 can be controlled using fluid pressure in the steering system 100 or by another control method (e.g., applying force to the isolation spool 224 with a solenoid or other actuator, etc.). In the non-limiting example shown, the isolation spool 224 is moved using fluid pressure in the steering system 100. More specifically, the isolation spool 224 includes a pressure connection 256 (e.g., a first load sensing or pilot pressure connection or chamber) that is disposed on a second end of the isolation spool 224, opposite the biasing assembly 228. As such, the fluid pressure applied at the pilot pressure connection is configured to act against the force of the first compliance member 232 and the second compliance member 236, thereby compressing the spring and moving the isolation spool 224.

[0056] The pressure connection 256 is connected to the pump port 152 and can be selectively coupled to the tank port 156 to control the pressure at the pressure connection 256, thereby controlling the position and steering mode of the isolation valve spool 224. More specifically, the pressure connection 256 can be coupled to the tank 112 (e.g., vented to the tank) to reduce the pressure at the pressure connection 256, thereby allowing the biasing assembly 228 to move the isolation valve spool 224 to the first isolation position. In some cases, a throttle orifice 268 can be provided between the pump port 152 and the pressure connection 256 to limit the flow from the pump 108 through the pressure connection 256 to the tank 112. The throttle orifice 268 can also reduce the pressure at the pressure connection 256.

[0057] Conversely, blocking the pressure connection 256 from the reservoir 112 allows the pressure at the pressure connection 256 to increase, which causes the first compliance member 232 to compress to move the isolation spool 224 to the second isolation position or the third isolation position depending on the amount of pressure. With the reservoir 112 blocked, changes in the pressure of the steering system 100 (e.g., depending on actuator consumption) can compress the second compliance member 236 to change the isolation spool 224 between the second isolation position and the third isolation position. For example, movement of the directional control spool 184 to each of the second and third directional positions will increase the fluid consumption of the actuator 104, thereby reducing the pressure at the pressure connection 256. This causes a force imbalance at the isolation spool 224, so that the second compliance member 236 will extend and automatically move the isolation spool 224 toward the second isolation position to provide the desired flow. Correspondingly, movement of the directional control spool 184 to the first directional position will reduce the consumption of the actuator 104, resulting in pressure accumulation at the pressure connection 256, which compresses the second compliance member 236 and automatically moves the isolation spool 224 toward the third isolation position to discharge excess flow to the tank 112 via the manual steering valve 124.

[0058] Thus, by selectively connecting the pressure connection 256 to the reservoir 112, the steering system 100 can be switched between a manual steering mode and an automatic steering mode. Thus, only a single connection needs to be controlled to change the steering mode. As shown in the non-limiting example shown, an enable solenoid 264 (e.g., a proportional solenoid or an on / off solenoid, or another type of actuator, such as an EPRV) can be positioned between the pressure connection 256 and the reservoir port 156 to selectively couple the pressure connection 256 to the reservoir 112.

[0059] The enabling solenoid 264 can communicate with the controller 120. The controller 120 can command the enabling solenoid 264 to move between a first position (e.g., a disabled position) that couples the pressure connection 256 to the tank 112 and a second position (e.g., an enabled position) that blocks the pressure connection 256 from the tank 112. It should be understood that the enabling solenoid 264 can be a normally open solenoid so that it moves to the first position only when the controller 120 issues a command (e.g., energizes). Therefore, the controller 120 can effectively move the isolation valve core 224 between the first isolation position and the second isolation position according to the desired steering mode. For example, in some cases, the controller 120 can control the enabling solenoid according to an operator command or based on another input (e.g., a sensor input). In some cases, the controller 120 can be configured to automatically switch from the electronic steering mode to the manual steering mode when the operator provides a steering command or other command at the manual input device 106.

[0060] In some cases, the isolation valve core 224 can also include a second pressure connection 260 (e.g., a load sensing or pilot pressure connection or chamber) that is disposed on the same side as the biasing assembly 228 (i.e., opposite the first pressure connection 256). The second pressure connection 260 can be coupled to the pump 108 and the reservoir 112 via the directional control valve core so that the pressure at the second pressure connection 260 can work with the spring force provided by the second compliance member 236 to control the movement between the second isolation position and the third isolation position. More specifically, the second pressure connection 260 can be coupled between the pressure relief valve 158 and the directional control valve core 184. Correspondingly, the orifice 288 can be positioned between the second pressure connection 260 and the directional control valve core 184 so that the pressure at the second pilot pressure connection is the same as the pressure at the pressure relief valve 158.

[0061] In other non-limiting examples, the electronic steering valve may be configured differently. Figure 6-Figure 9 2 shows aspects of another non-limiting example of a steering system 200. It should be understood that the steering system 200 is generally similar to the steering system 100 except as follows. Figure 6As best shown in FIG. 1 , an orifice 302, 304 may be provided between each of the first EPRV 212 and the second EPRV 216 and the directional control spool 184 to limit flow between each of the first pilot pressure connection 220 and the second pilot pressure connection 222 and the pump port 152. The orifices 302, 304 function as damping orifices that limit flow into or out of the pilot pressure connections 220 and 222 and inhibit movement of the directional control spool 184. For example, when the directional control spool 184 moves toward the second directional position, the pressure at the first pilot pressure connection 220 will temporarily decrease to less than the pressure provided by the first EPRV 212, while the pressure at the second pilot pressure connection 222 will temporarily increase. Similarly, when the directional control spool 184 moves toward the third directional position, the pressure at the second pilot pressure connection 222 will temporarily decrease to less than the pressure provided by the second EPRV 216, while the pressure at the first pilot pressure connection 220 will temporarily increase. The orifices 302, 304 can slow down the rate of change of the pressure at the pilot pressure connections 220, 222, thereby inhibiting the movement of the directional control spool 184.

[0062] Additional references Figure 7-Figure 9 , the biasing assembly 228 includes a single compliance member 310 (e.g., a spring or other resilient member) that extends between and is retained between the first seat 240 and the third seat 248. Thus, the compliance member 310 can extend between the valve body 148 and the isolation valve core 224. It should be understood that the compliance member 310 can be provided with an initial preload compression so as to bias the isolation valve core 224 to the first isolation position. In addition, the compliance member 310 can be compressed to allow the isolation valve core 224 to move between each of the three isolation positions. In this way, the compliance member 310 can act to isolate the directional control valve core 184 and move to maintain a boundary pressure on the isolation valve core 224, thereby controlling the unloading of excess pump flow to the tank 112 in the electronic steering mode.

[0063] Correspondingly, the isolation valve core 224 can be configured so that the isolation valve core 224 can be moved back and forth between the first isolation position (see, for example, Figure 7) selectively couples the second pressure connection 260 to the reservoir 112. More specifically, in the first isolation position, the isolation valve core 224 can couple the second pressure connection 260 to the reservoir 112 so that the second pressure connection 260 is discharged through the isolation valve core 224. This reduces the pressure on the second pressure connection 260 so that when the first pressure connection 256 (e.g., via the enabling solenoid 264) is coupled to the reservoir 112, the compliance member 310 can bias the isolation valve core to the first isolation position. Correspondingly, when the first pressure connection 256 is blocked from the reservoir 112, the isolation valve core 224 can move to the second isolation position or the third isolation position (see, e.g., Figure 8 and Fig. 9 ), which blocks the second pressure connection 260 from the tank 112 and allows pressure to accumulate. Relatedly, the directional control valve spool 184 can include orifices 320, 322 that can limit flow from the pump 108 to the second pressure connection 260. Additionally, in some cases, the second pressure connection 260 can be coupled between the tank port 156 and the spring-biased check valve 166 to prevent flow from the second pressure connection 260 to the directional control valve spool 184.

[0064] In this specification, embodiments are described in a manner that enables clear and precise descriptions to be written, but it is intended and will be understood that various combinations or splits of these embodiments can be made without departing from the present invention. For example, it should be understood that all preferred features described herein can be applied to all aspects of the invention described herein.

[0065] Thus, although the invention has been described in conjunction with particular embodiments and examples, the invention is not necessarily so limited, and various other embodiments, examples, uses, modifications and deviations to the various embodiments, examples and uses are intended to be covered in the appended claims. The entire disclosure of each patent and publication cited herein is incorporated herein by reference, as if each patent or publication was individually incorporated herein by reference.

[0066] Various features and advantages of the invention are set forth in the following claims.

Claims

1. A control valve for a hydraulic machine steering system, the control valve comprising: a valve body defining a first actuator port, a second actuator port, a tank port, a pump port, and a manual steering interface; a directional control spool disposed in the valve body to selectively couple the first actuator port, the second actuator port, the tank port, and the pump port; as well as An isolation spool is disposed within the valve body to selectively couple the directional control spool to each of the first actuator port, the second actuator port, and the pump port, and to selectively couple the pump port to the manual steering interface.

2. The control valve according to claim 1, characterized in that: The directional control spool is configured to move between each of: a first directional position coupling each of the first actuator port and the second actuator port to the tank port; a second directional position coupling the pump port to the first actuator port and coupling the second actuator port to the tank port; as well as A third directional position couples the pump port to the second actuator port and couples the first actuator port to the tank port.

3. The control valve according to claim 2, characterized in that: Also included is a biasing assembly configured to bias the directional control valve spool to the first directional position.

4. The control valve according to claim 3, characterized in that: The biasing assembly includes a first directional control spring and a second directional control spring in opposite configurations about the directional control valve spool to bias the directional control valve spool to the first directional position.

5. The control valve according to claim 3, characterized in that: Also includes: a first electronically controlled pressure regulating valve configured to move the directional control valve spool from the first directional position to the second directional position; as well as A second electronically controlled pressure regulating valve is configured to move the directional control spool from the first directional position to the third directional position.

6. The control valve according to claim 5, characterized in that Each of the first and second electronically controlled pressure regulating valves is movable between a first position coupling a corresponding pilot pressure connection of the directional control spool to the tank port and a second position coupling the corresponding pilot pressure connection to the pump port.

7. The control valve according to claim 1, characterized in that: The isolation spool is configured to move between each of: a first isolation position that blocks the first actuator port and the second actuator port from the directional control valve spool and couples the pump port to the manual steering interface; a second isolation position that blocks the manual steering interface from the pump port and couples the directional control valve spool to each of the first actuator port, the second actuator port, and the pump port; as well as A third isolation position couples the pump port to the manual steering interface and couples the directional control spool to each of the first actuator port, the second actuator port, and the pump port.

8. The control valve according to claim 7, characterized in that: Also included is a first isolation spring configured to bias the isolation valve spool to the first isolation position.

9. The control valve according to claim 8, characterized in that Also included is a second isolation spring arranged in series with the first isolation spring to bias the isolation valve spool to the first isolation position.

10. The control valve according to claim 8, characterized in that The pressure connection of the isolation valve spool is coupled to the pump port and further includes an enable solenoid to selectively couple the pressure connection to the tank port to control movement of the isolation valve spool.

11. The control valve according to claim 10, characterized in that The pressure connection part is a first pressure connection part, and further includes a second pressure connection part of the isolation valve core arranged opposite to the first pressure connection part.

12. The control valve according to claim 10, characterized in that The enabling solenoid is configured as one of a switching solenoid and a proportional solenoid.

13. The control valve according to claim 10, characterized in that Also included is a flow restriction orifice positioned between the pump port and the pressure connection.

14. The control valve according to claim 10, characterized in that The enabling solenoid can operate between each of the following: a disabled position coupling the pressure connection to the tank port such that the isolation valve spool is biased to the first isolation position; and An enabled position, the enabled position blocks the pressure connection from the tank port, so that the pressure at the pump port moves the isolation valve core from the first isolation position toward the second isolation position.

15. The control valve according to claim 14, characterized in that With the enabling solenoid in the enabling position, the position of the isolation spool is continuously variable between the second isolation position and the third isolation position based on the pressure at the pressure connection.

16. The control valve according to claim 1, characterized in that The manual steering interface is configured to couple with a manual steering valve and includes a pump connection, a tank connection, a first actuator connection, and a second actuator connection.

17. A steering system for a hydraulic machine having a pump, an actuator and a tank, the steering system comprising: a manual steering valve, the manual steering valve comprising a first pump connection portion, a first tank connection portion, a first actuator connection portion, and a second actuator connection portion, the manual steering valve being configured to selectively couple the first pump connection portion, the first tank connection portion, the first actuator connection portion, and the second actuator connection portion; and An electronic steering valve, the electronic steering valve comprising: a valve body defining: a pump port configured to couple to the pump, a first actuator port configured to couple to the actuator, a second actuator port configured to couple to the actuator, a tank port configured to couple to the tank, a second pump connection configured to couple to the first pump connection, a second tank connection configured to couple to the first tank connection, a third actuator connection configured to couple to the first actuator connection, and a fourth actuator connection configured to couple to the second actuator connection; a directional control spool disposed in the valve body, the directional control spool configured to selectively couple the pump port, the first actuator port, the second actuator port, and the tank port; and An isolation valve core is arranged in the valve body, and the isolation valve core is configured to switch the steering system between a manual steering mode and an electronic steering mode. In the manual steering mode, the directional control valve core is disconnected from the pump port, the first actuator port and the second actuator port through the isolation valve core. In the electronic steering mode, the directional control valve core is connected to the pump port, the first actuator port and the second actuator port through the isolation valve core.

18. The steering system according to claim 17, characterized in that The third actuator connection portion is in direct communication with the first actuator port, and the fourth actuator connection portion is in direct communication with the second actuator port.

19. The steering system according to claim 17, characterized in that: In the manual steering mode, the isolation spool is in a first isolation position that blocks the first and second actuator ports from the directional control spool and couples the pump port to the manual steering valve.

20. The steering system according to claim 19, characterized in that In the electronic steering mode, the isolation spool can move between each of the following: a second isolation position that isolates the manual steering valve from the pump port and couples the directional control spool to each of the first actuator port, the second actuator port, and the pump port; as well as A third isolation position couples the pump port to the manual steering valve and couples the directional control spool to each of the first actuator port, the second actuator port, and the pump port.

21. The steering system according to claim 17, characterized in that Also included is an electronic controller configured to move the isolation spool to switch between the manual steering mode and the electronic steering mode.

22. The steering system according to claim 21, characterized in that The electronic controller is configured to operate an enable solenoid configured to selectively couple a pressure connection of the isolation spool to the tank port to place the steering system in the manual steering mode and to decouple the pressure connection from the tank port to place the steering system in the electronic steering mode.

23. The steering system according to claim 21, characterized in that In the electronic steering mode, the electronic controller is configured to operate the first electronically controlled pressure regulating valve and the second electronically controlled pressure regulating valve to move the directional control spool between each of: a first directional position coupling each of the first actuator port and the second actuator port to the tank port; a second directional position coupling the pump port to the first actuator port and coupling the second actuator port to the tank port; as well as A third directional position couples the pump port to the second actuator port and couples the first actuator port to the tank port.

24. The steering system according to claim 17, characterized in that The actuator includes a first actuator coupled to the first actuator port and a second actuator coupled to the second actuator port.

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