SYSTEM AND METHOD FOR CONTROLLING OPERATION OF HYDRAULIC VALVE

A system for controlling operation of a hydraulic valve is provided. The system includes a solenoid coupled to a spool assembly of the hydraulic valve. The system further includes a sensor disposed on the hydraulic valve. The sensor generates signals indicative of operational parameter of the hydraulic valve. The system also includes a controller in communication with the solenoid and the sensor. The controller receives signals generated by the sensor. The controller includes a booster circuit connected to the solenoid. The booster circuit boosts an actuating current generated in response to the signals received from the sensor. The controller further includes a switching circuit connected across the solenoid. The switching circuit controls a direction of the actuating current flowing through the solenoid. The solenoid actuates the spool assembly of the hydraulic valve to control the operation of the hydraulic valve based on the actuating current.

TECHNICAL FIELD

The present disclosure relates to a hydraulic system, and more particularly relates to a system and a method for controlling operation of a hydraulic valve of the hydraulic system.

BACKGROUND

Machines, such as excavators and loaders, include hydraulic system for operating various systems, such as an implement system, a lubrication system, and a braking system. The hydraulic system includes one or more hydraulic valves for controlling flow of fluid to multiple actuators, such as a hydraulic cylinder, through multiple hydraulic lines. The hydraulic valve includes a hollow spool for selectively allowing or restricting flow of fluid from pump to multiple actuators. Generally, the hydraulic valve may have considerably less frequency response range, for example, 7 Hz to 8 Hz at a 90 degree phase. Typically, the hydraulic valve is controlled by an electronic control module (ECM) of the machine. The hydraulic valve has a solenoid that is in electronic communication with the ECM of the machine. The ECM energizes or de-energizes the solenoid for controlling movement of the spool to operate the hydraulic valve. The machine includes mechanical devices, such as mechanical compensators and line relief valves, for enhancing the frequency response of the hydraulic valve. However, in conventional hydraulic valve, advanced programmable features of the ECM may not be implemented effectively due to design limitations of the hydraulic valve components, such as spools, and the less frequency response of the hydraulic valve.

U.S. Pat. No. 8,006,718, hereinafter referred to as ‘the '718 patent, discloses a sleeve having an input port, an output port, an insertion hole, and a discharge port. A spool is axially slidable through the insertion hole to communicate among the input port, the output port, and the discharge port. An electric actuator is provided to one end of the sleeve and has a variable volume chamber, which communicates with the discharge port through an axial through hole and a spool breathing hole in the spool. The spool has a communication through hole to lead fluid from the output port to the discharge port through the axial through hole. A passage partition member is in the axial through hole to define an in-spool breathing passage communicating with the spool breathing hole. However, the '718 patent fails to disclose an effective method to increase the frequency response of the hydraulic valve.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a system for controlling operation of a hydraulic valve is provided. The system includes a solenoid coupled to a spool assembly of the hydraulic valve. The system further includes a sensor disposed on the hydraulic valve. The sensor is configured to generate signals indicative of one or more operational parameters of the hydraulic valve. The system also includes a controller in communication with the solenoid and the sensor. The controller is configured to receive signals generated by the sensor. The controller includes a booster circuit connected to the solenoid. The booster circuit is configured to boost an actuating current generated in response to the signals received from the sensor. The controller further includes a switching circuit connected across the solenoid. The switching circuit is configured to control a direction of the actuating current flowing through the solenoid. The solenoid is configured to actuate the spool assembly within a valve body of the hydraulic valve to control the operation of the hydraulic valve based on the actuating current.

In another aspect of the present disclosure, a method of controlling operation of a hydraulic valve is provided. The method includes generating signals indicative of one or more operational parameters of the hydraulic valve by a sensor. The method further includes receiving the signals generated by the sensor by a controller. The method also includes generating an actuating current in response to the signals received from the sensor by the controller. The method also includes actuating a spool assembly of the hydraulic valve based on the actuating current by a solenoid and controlling the actuating current by a booster circuit and a switching circuit associated with the controller.

In yet another aspect of the present disclosure, a method of controlling operation of a hydraulic valve is provided. The method includes generating signals indicative of one or more operational parameters of the hydraulic valve by a sensor. The method also includes receiving the signals generated by the sensor by a controller. The method also includes generating an actuating current in response to the signals received from the sensor by the controller. The method also includes actuating a spool assembly of the hydraulic valve based on the actuating current by a solenoid. The method also includes controlling the actuating current by boosting the actuating current flowing through the solenoid by a booster circuit and controlling a direction of the actuating current flowing through the solenoid by a switching circuit.

DETAILED DESCRIPTION

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts.FIG. 1illustrates an exemplary hydraulic circuit100for operating one or more tool actuators102. The one or more tool actuators102may be used in machines (not shown), such as excavators, loaders, and other machines having implements for performing earth moving operations and other known industrial operations. The one or more tool actuators102are movable based on an input received from an operator of the machine. Referring toFIG. 1, two tool actuators102are shown that are arranged to operate in tandem. The one or more tool actuators102are hereinafter referred to as “the tool actuator102”. In one example, the tool actuator102is a linear actuator, such as a cylinder with piston arrangement.

In the illustrated embodiment, the tool actuator102includes a tube104and a piston106arranged within the tube104to form a first chamber108and a second chamber110. The first chamber108and the second chamber110may be selectively supplied with pressurized fluid to cause the piston106to displace within the tube104, and thereby changing an effective length of the tool actuator102.

The hydraulic circuit100includes a pump116configured to draw fluid from a sump118, to pressure the fluid, and to direct the fluid through a valve assembly120to the tool actuator102. The pump116may be fluidly connected to the sump118by a suction passage122, and to the valve assembly120via a pressure passage124. The pump116may be driven by a power source, such as an engine of the machine. The sump118is connected to the valve assembly120via a drain passage126. The hydraulic circuit100may also include various control valves (not shown), such as relief valves, check valves, directional control valves, in fluid communication with the drain passage126and the pressure passage124to maintain a desired pressure of the fluid within the hydraulic circuit100.

The valve assembly120is in fluid communication with the first chamber108and the second chamber110of the tool actuator102via a rod end passage128and a head end passage130, respectively. The valve assembly120selectively controls flow of the fluid to the head end passage130and the rod end passage128to cause movement of the piston106of the tool actuator102. The valve assembly120includes multiple hydraulic valves132for controlling the flow of fluid into and out of the head end passage130and the rod end passage128. One hydraulic valve132of the multiple hydraulic valves132of the valve assembly120is explained in detail hereinafter. The hydraulic circuit100includes a system134that is in communication with the hydraulic valve132. The system134is configured to receive the input provided by the operator and control an operation of the hydraulic valve132. The system134includes multiple solenoids136. Each of the multiple solenoids136is coupled to one of the hydraulic valve132of the multiple hydraulic valves132. The system134further includes a controller138in communication with the multiple solenoids136. For explanatory purpose, one solenoid136of the multiple solenoids136is explained in detail hereinafter. The functionalities of the system134and various components of the system134are explained in detail hereinbelow.

FIG. 2illustrates a schematic diagram of the system134for controlling the operation of the hydraulic valve132, according to an embodiment of the present disclosure. In one embodiment, the hydraulic valve132includes a valve body140, a spool assembly142slidably disposed within a bore143defined in the valve body140, and an actuator144to control movement of the spool assembly142within the valve body140. The valve body140of each of multiple hydraulic valves132may be fastened to form the valve assembly120. In an alternate embodiment, the valve assembly120includes a single valve body (as shownFIG. 1) and multiple spool assemblies disposed within multiple bores defined in the single valve body140. Also, multiple actuators are connected to the single valve body. The hydraulic valve132includes an inlet port145and an outlet port146defined in the valve body140. The flow of fluid from the inlet port145to the outlet port146is controlled by the spool assembly142.

The spool assembly142includes a hollow cylindrical body148extending from a first end150to a second end152. The hollow cylindrical body148includes multiple radial orifices154in a wall156of the hollow cylindrical body148. The spool assembly142further includes an insert158slidably disposed inside the hollow cylindrical body148. A linear movement of the spool assembly142within the valve body140hydraulically connects the inlet port145with the outlet port146of the hydraulic valve132. The hydraulic valve132controls the flow of the fluid by controlling the axial movement of the spool assembly142within the valve body140.

Referring toFIG. 1andFIG. 2, the actuator144is a pilot line. The pilot line may be fluidly connected to the second end152of the spool assembly142. The pilot line may cause the spool assembly142of the hydraulic valve132to move between different positions. The pilot line allows pilot fluid to flow from a pilot pump162through a pilot passage164to the hydraulic valve132. The pilot line can also include an accumulator to maintain a desired pressure of the pilot fluid in the pilot line during actuation of the hydraulic valve132. In another embodiment, the hydraulic valve132may be actuated by a linear motor (not shown) operatively coupled to the spool assembly142. In yet another embodiment, the actuator144that is drivably coupled to the spool assembly142may be a proportional pressure reducing valve known in the art.

As mentioned earlier, the operation of the hydraulic valve132is controlled by the system134in response to various operating parameters of the hydraulic valve132, such as a flow rate of the fluid, and a pressure of the fluid communicated with the tool actuator102. The solenoid136of the system134is coupled to the spool assembly142of the hydraulic valve132. The solenoid136is an electromagnetic-inductive coil movably wound around a plunger (not shown). The plunger is movably coupled to the spool assembly142. The solenoid136is configured to generate a magnetic field when energized by an actuating current. Based on the magnetic field, the plunger may exhibit a linear motion. The movement of the plunger is controlled by a magnitude and a direction of the actuating current applied to the solenoid136. More specifically, the solenoid136may have an electrical characteristic of an inductor such as opposing a flow of the actuating current through the solenoid136. Hence, the actuating current rises at a steady rate until it is limited by a DC resistance of the solenoid136. As soon as the solenoid136is energized, the actuating current increases and causes the magnetic field to expand until it becomes strong enough to move the plunger of the solenoid136. Thus, the spool assembly142of the hydraulic valve132moves to establish a fluid connection between the inlet port145and the outlet port146. When the solenoid136is de-energized, the spool assembly142of the hydraulic valve132moves to disconnect a fluid connection between the inlet port145and the outlet port146.

The system134further includes a sensor168disposed in the hydraulic valve132. The sensor168is configured to generate signals indicative of one or more operational parameters of the hydraulic valve132including, but not limited to, the pressure of the fluid, and a displacement of the spool assembly142within the valve body140. In one embodiment, the sensor168may be a pressure sensor configured to generate signals indicative of the pressure of the fluid flowing through the hydraulic valve132. The pressure sensor may be disposed at the outlet port146of the hydraulic valve132. In another embodiment, the pressure sensor may be disposed at the inlet port145of the hydraulic valve132. In other embodiments, the sensor168may be disposed at any location in the hydraulic valve132to detect pressure of the fluid flowing through the hydraulic valve132. In another embodiment, the sensor168may be a displacement sensor configured to generate signals indicative of the displacement of the spool assembly142within the valve body140of the hydraulic valve132. The displacement of the spool assembly142within the valve body140indicates amount of fluid flowing from the inlet port145to the outlet port146.

The controller138of the system134is in communication with the solenoid136and the sensor168. The controller138implements a communication channel, such as Controller Area Network (CAN) to communicate with the sensor168and the solenoid136. In one embodiment, the controller138is an Electronic Control Module (ECM) of the engine of the machine. The controller138may be an embedded system configured to provide real time regulation for the hydraulic valve132. The controller138may include a processor including a single processing unit or multiple processing units, each of which may include a plurality of computing units. The controller138may be implemented as one or more microprocessors, microcomputers, digital signal processor, central processing units, state machine, logic circuitries, and any device that is capable of manipulating signals based on operational instructions. Among the capabilities mentioned herein, the controller138may also be configured to receive, transmit, and execute computer-readable instructions. In an embodiment, the controller138may be implemented in the machine to control various components of the machine including, but not limited to, a transmission system, a braking system, a suspension system, an exhaust system, a steering system, and an implement system. The functionalities of the controller138and various modules of the controller138are explained in detail with reference toFIG. 3. In another embodiment, the machine may include multiple controllers138configured to control one of various components of the machine including, but not limited to, the transmission system, the braking system, the suspension system, the exhaust system, the steering system, and the implement system. Each of the multiple controllers138is configured to communicate with each other for collectively controlling an operation of the machine.

In an embodiment, the controller138is configured to generate an actuating current I1at time T1in response to the input provided by the operator to actuate the spool assembly142of the hydraulic valve132. The actuating current I1is communicated to the solenoid136for actuating the spool assembly142to operate the hydraulic valve132. Thus, the spool assembly142of the hydraulic valve132allows the fluid connection between the inlet port145and the outlet port146of the hydraulic valve132. The solenoid136initiates the axial movement of the spool assembly142of the hydraulic valve132based on the actuating current I1. The sensor168disposed in the hydraulic valve132may act as a feedback signaling device. The sensor168senses the operational parameters of the hydraulic valve132during the operation of the hydraulic valve132and generates the signals indicative of the operational parameters of the hydraulic valve132. Further, the generated signals are communicated to the controller138for regulating the operation of the hydraulic valve132. The controller138is configured to receive the signals generated by the sensor168. The controller138is configured to determine the operational parameters from the signals and to generate a compensating current in response to the signals received from the sensor168. The controller138is further configured to generate an actuating current I2at time T2based on the compensating current and the input provided by the operator.

FIG. 3illustrates a schematic block diagram of the controller138of the system134, according to one embodiment of present disclosure. The controller138includes a controlling module169and a processing module170. The controlling module169is configured to generate the actuating current in response to the input received from the operator and the signals received from the sensor168. The actuating current generated by the controlling module169is communicated to the processing module170. The processing module170includes a booster circuit171. The actuating current required to energize or de-energize the solenoid136is referred to as ‘the peak current’. The booster circuit171boosts the actuating current to increase the magnitude thereof till a magnitude of the peak current reaches. Further, the boosted actuating current is supplied to the solenoid136to energize the solenoid136to establish the fluid connection between the inlet port145and the outlet port146. Also, the boosted actuating current is supplied to the solenoid136to de-energize the solenoid136to disconnect the fluid connection between the inlet port145and the outlet port146. The booster circuit171amplifies the actuating current at voltage up to 105V over milliseconds. In one embodiment, the booster circuit171may be a voltage boost driver known in the art.

The processing module170further includes a switching circuit172connected across the solenoid136. The switching circuit172is configured to connect the solenoid136with at least one of a battery of the machine and the boost circuit171. The switching circuit172controls the direction of the actuating current flowing through the solenoid136. The switching circuit172is connected across the solenoid136, such that the direction of the actuating current may be switched in forward or reverse directions. In the present embodiment, the switching circuit172is a H-bridge.

The processing module170further includes a digital logic circuit174. The digital logic circuit174includes a processor178and a field programmable gate array (FPGA)180. The actuating current required to maintain the energized or de-energized state of the solenoid136is referred to as ‘the holding current’. The holding current is significantly less than the peak current. In order to bring the magnitude of the actuating current to a magnitude of the holding current in the solenoid136for a predetermined time, the digital logic circuit174implements a proportional logic known in the art, without limiting the scope of the present disclosure. The proportional logic derives the holding current from the actuating current for holding the solenoid136at the energized state and hence to maintain desired flow rate of the fluid between the inlet port145and the outlet port146of the hydraulic valve132. The digital logic circuit174holds the actuating current at a voltage provided by at least one of the battery and the boost circuit171for the predetermined time. The predetermined time is defined as a time interval for which the solenoid136needs to be energized to keep the spool assembly142at an open position and hence to establish the fluid communication between the inlet port145and the outlet port146. The predetermined time may also be defined as the time interval for which the solenoid136needs to be de-energized to keep the spool assembly142at a closed position to disconnect the fluid communication between the inlet port145and the outlet port146.

The actuating current generated by the controlling module169is boosted by the booster circuit171for a predefined time period. In an example, the predefined time period may be 2 milliseconds. The booster circuit171boosts the actuating current to the peak current by boosting an input voltage provided to the booster circuit171. The actuating current spikes to reach the peak current required for energizing or de-energizing the solenoid136due to the boosting of the input voltage. Further, the FPGA180of the digital logic circuit174is configured to induce a dither in the actuating current. The dither is a ripple frequency that is superimposed over the actuating current applied to the solenoid136, which causes a desired movement of the spool assembly142of the hydraulic valve132. The application of dither leverages the energizing and de-energizing state thereby increases the frequency response of the solenoid136. In another embodiment, the booster circuit171is a current booster circuit.

The switching circuit172is connected across the solenoid136for controlling the direction of the actuating current. The FPGA180of the digital logic circuit174is connected to the switching circuit172to control the switching circuit172. More specifically, the switching circuit172includes at least two pairs of switching devices (not shown). In one example, the pair of switching devices is Field Effect Transistors (FETs). Each pair of the switching devices is controlled by the FPGA180. For example, the FPGA180is configured to turn ON and turn OFF each pair of the switching devices to apply the actuating current through the solenoid136in the forward or reverse directions. The first pair of switching devices is controlled by the FPGA180to direct the actuating current in to the solenoid136. The second pair of the switching devices is controlled by the FPGA180to direct the actuating current out of the solenoid136. The direction of flow of the actuating current is directly proportional to a direction of magnetic field generated by the solenoid136and the direction of movement of the plunger. Hence, the implementation of the switching circuit172controls the linear movement of the spool assembly142within the valve body140with limited time delay thereby increasing the frequency response of the hydraulic valve132.

In another embodiment, the controller138may include multiple processing modules170. Each of the multiple processing modules170is coupled to one of the multiple solenoids136. The multiple processing modules170are configured to communicate with each other for coordinating an operation of the multiple hydraulic valves132of the valve assembly120. In yet another embodiment, the system134may include multiple controllers138. Each of the multiple controllers138includes at least one processing module170. Each of the multiple controllers138is configured to communicate to each other. Each of the multiple controllers138is coupled to one of the multiple solenoids136to control the operation of the valve assembly120.

INDUSTRIAL APPLICABILITY

The present disclosure relates to the system134and a method182for controlling the operation of the hydraulic valve132. The system134improves the frequency response of the hydraulic valve132by reducing the response time. The booster circuit171is capable of boosting the actuating current till the peak current required to energize and de-energize the solenoid136within a short time interval, for example 2 milliseconds. The boosting of the actuating current within the short time interval increases the frequency response of the solenoid136. The switching circuit172drives energy in and out of the solenoid136. The digital logic circuit174is configured to regulate the flow of the actuating current through the solenoid136. Further, the spool assembly142of the hydraulic valve132includes the hollow cylindrical body148. The hollow cylindrical body148of the spool assembly142reduces the amount of fluid that needs to be purged through the spool assembly142, which in turns makes movement of the spool assembly142faster than the conventional spools.

FIG. 4illustrates a flow chart of the method182of controlling the operation of the hydraulic valve132. For the sake of brevity, various embodiments of the present disclosure, which are already explained in detail in the description ofFIG. 1,FIG. 2, andFIG. 3, are not explained in detail with regard to the description of the method182. As mentioned earlier, the hydraulic valve132is controlled by the solenoid136, which is attached to the spool assembly142of the hydraulic valve132. The spool assembly142moves within the valve body140based on the input received by the solenoid136to establish or disconnect the fluid connection between the inlet port145and the outlet port146of the hydraulic valve132.

At step184, the method182includes generating the signals indicative of the one or more operational parameters of the hydraulic valve132by the sensor168. The sensor168includes, but not limited to, the pressure sensor and the displacement sensor. The operational parameter may include pressure of the fluid flowing through the inlet port145and the outlet port146of the hydraulic valve132. The operational parameters further include displacement of the spool assembly142. The signals generated by the sensor168may act as a feedback signal to the controller138.

At step186, the method182includes receiving the signals by the controller138. The signals enable the controller138to determine a change in the actuating current required to meet the desired displacement of the spool assembly142of the hydraulic valve132. At step188, the method182further includes generating the actuating current in response to the signals received from the sensor168by the controller138and the input provided by the operator. As mentioned earlier, the controller138includes the controlling module169for generating the actuating current corresponding to the signals.

At step190, the method182includes actuating the spool assembly142of the hydraulic valve132based on the actuating current by the solenoid136. The controller138communicates the actuating current with the solenoid136. The actuating current energizes and de-energizes the solenoid136, which in turn causes the linear movement of the spool assembly142from the closed position to the open position within the valve body140. The linear movement of the spool assembly142fluidly connects the inlet port145and the outlet port146of the hydraulic valve132. The solenoid136is coupled to the first end150of the spool assembly142and the actuator144is coupled to the second end152of the spool assembly142. The solenoid136actuates the spool assembly142within the valve body140of the hydraulic valve132in response to the actuation of the spool assembly142by the actuator144. In one embodiment, the actuator144is the pilot line in fluid communication with the hydraulic valve132.

At step192, the method182includes controlling the actuating current by the booster circuit171and the switching circuit172to enhance the frequency response of the solenoid136thereby reducing the time delay in energizing and de-energizing the solenoid136. Controlling the actuating current includes boosting the actuating current flowing through the solenoid136by the booster circuit171. The solenoid136may require approximately 30% more actuating current while energizing the solenoid136than the actuating current generated by the controlling module169. Hence, the booster circuit171boosts the actuating current to the peak current. The controlling of the actuating current further includes controlling the direction of the actuating current flowing through the solenoid136by the switching circuit172. As mentioned earlier, the switching circuit172includes at least two pairs of switching devices. The first pair of switching devices is enabled by the FPGA180to direct the actuating current into the solenoid136. The second pair of the switching devices is enabled by the FPGA180to direct the actuating current out of the solenoid136. Controlling the actuating current also includes controlling the flow of the actuating current in the solenoid136for the predetermined time by the proportional logic of the digital logic control174.