CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of Indian Patent Application No. 202011039112, filed on September 10, 2020, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Work machines, such as fork lifts, wheel loaders, track loaders, excavators, backhoes, bull dozers, fire trucks, mobile and truck cranes, material handlers, and telehandlers are known. Work machines can be used to move material, such as pallets, dirt, and/or debris. The work machines typically include a work implement (e.g., a fork) connected to the work machine. The work implements attached to the work machines are typically powered by a hydraulic system. The hydraulic system can include a hydraulic pump that is powered by a prime mover, such as a diesel engine. The hydraulic system typically includes a number of work sections for operating actuators via control valve assemblies. Some control valve assemblies are highly complex and perform numerous functions for the hydraulic system. With such complexity, certain operating efficiencies can be achieved, but the costs for such systems has increased significantly. In contrast, some work machines need simple valve control with robustness as a priority. For such applications, operating efficiencies are also desirable.

SUMMARY

[0003] The disclosure includes a work section which converts an inlet pump system from variable to fixed displacement on a mobile sectional control valve having pre and or post compensated sections stacked together. In some applications, some work sections or functions in a complete valve bank do not need high performance control of the flow. Such functions can be non-pressure compensated. For example, functions like stabilizers and outriggers on a machine do not need precise control and speeds depending upon load and such functions can be accomplished without high performance flow. By providing some sections with reduced features, costs can be reduced significantly. Advantageously, this disclosure provides a section design that is suitable to accommodate in a valve bank where other sections are of pre and post compensated type.

[0004] A hydraulic system can include a pump having a load-sense control arrangement configured for variable displacement operation of the pump, a reservoir, a plurality of hydraulic actuators, and a sectional valve assembly including multiple stacked work sections, wherein each of the plurality of work sections is in fluid communication with one of the plurality of hydraulic actuators, the pump, the reservoir, and the load-sense arrangement, the sectional valve assembly including at least one first work section having a spool disposed in a housing to form a first control valve assembly, wherein the first work section has a first position in which the pump is operated in a variable displacement mode and has a second position in which the pump is operated in a fixed displacement mode.

[0005] In some examples, the first control valve assembly has an actuator first port, an actuator second port, a pump port, a tank port, and a load sense port, the first control valve assembly being operable in first, second, and third positions. In the first position, flow between the pump, tank, actuator first and second ports, and the load sense port is blocked, wherein the pump is enabled to operate in a variable displacement mode to enable the others of the plurality of work sections to operate in a pre or post compensated mode. In the second position, flow between the actuator first port and the pump is enabled, flow between the actuator second port and the tank is enabled, and the loadsense port is placed in fluid communication with the actuator first port and the pump such that the pump is operated in a fixed displacement mode, non-compensated mode. In the third position, flow between the actuator first port and the tank is enabled, flow between the actuator second port and the pump is enabled, and the load-sense port is placed in fluid communication with the actuator second port and the pump such that the pump is operated in a fixed displacement mode, non-compensated mode.

[0006] In some examples, the first work section is provided without compensator components and one or more of the remaining work sections is provided with compensator components. [0007] In some examples, a load-sense check valve is located between the load sense port and the load-sense arrangement.

[0008] A control valve assembly can include a spool disposed within a housing having an actuator first port, an actuator second port, a pump port, a tank port, a load sense gallery port, the spool being operable in first, second, and third positions. In the first position wherein flow between the pump port, tank port, actuator first and second ports, and the load sense gallery port is blocked. In the second position, flow between the actuator first port and the pump is enabled, flow between the actuator second port and the tank is enabled, and the load-sense gallery port is placed in fluid communication with the actuator first port and the pump. In the third position, flow between the actuator first port and the tank is enabled, flow between the actuator second port and the pump is enabled, and the load-sense gallery port is placed in fluid communication with the actuator second port and the pump.

[0009] In some examples, the control valve assembly is provided without compensator components.

[0010] In some examples, the control valve assembly is provided with a load-sense check valve in fluid communication with the load sense gallery port.

[0011] A control valve assembly work section can include a stackable main body including one or more through holes for receiving connecting rods, the main body defining a first bore, a second bore, an actuator first port, an actuator second port, a pump port, a tank port, and a load sense gallery port; and a spool movably disposed within first bore of the main body, the spool being movable within the first bore in first, second, and third positions. In the first position wherein flow between the pump port, tank port, actuator first and second ports, and the load sense gallery port is blocked. In the second position, flow between the actuator first port and the pump is enabled, flow between the actuator second port and the tank is enabled, and the load-sense gallery port is placed in fluid communication with the actuator first port and the pump. In the third position, flow between the actuator first port and the tank is enabled, flow between the actuator second port and the pump is enabled, and the load-sense gallery port is placed in fluid communication with the actuator second port and the pump. The section can further include a load-sense check valve disposed within the second bore and in fluid communication with the pump port and the load sense gallery port, the load-sense check valve preventing flow in a direction from the load sense gallery port towards the pump port and allowing flow in the opposite direction.

[0012] In some examples, the second bore is a compensator port in fluid communication with the pump port, tank port, and the load-sense gallery.

[0013] In some examples, the control valve assembly is provided without compensator components.

[0014] In some examples, the section includes a first plug at an end of the second bore.

[0015] In some examples, the first plug blocks fluid communication between the second bore and the tank port.

[0016] In some examples, the first plug abuts the load-sense check valve to secure the load-sense check valve within the second bore.

[0017] In some examples, the section includes a second plug at a second end of the second bore.

[0018] In some examples, one or both of the first and second plugs block fluid communication between the second bore and the tank port.

[0019] In some examples, the first and second plugs abut the load-sense check valve to secure the load-sense check valve within the second bore.

[0020] In some examples, the load-sense check valve is a spring check type valve.

[0021] In some examples, the load-sense check valve includes a main body defining a bore and movable valve portion disposed within the bore, the main body defining a first passageway in fluid communication with the pump port and a second passageway in fluid communication with the load-sense gallery port.

[0022] In some examples, the main body defines a plug portion disposed within an open end of the second bore.

[0023] In some examples, the main body includes one or more seals such that all fluid flowing from the pump port to the load-sense gallery port flows through the loadsense check valve.

[0024] In one aspect, the disclosed aspects of the present application can be used in conjunction with the system shown and described in United States Provisional Patent Application Serial Number 63/025,577, filed on May 15, 2020 an entitled “HYDRAULIC SYSTEM VALVE CONTROL”, the entirety of which is incorporated by reference herein.

DESCRIPTION OF THE DRAWINGS

[0025] Non-limiting and non-exhaustive embodiments are described with reference to the following figures, which are not necessarily drawn to scale, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

[0026] Figure 1 is a schematic view of a work machine having features that are examples of aspects in accordance with the principles of the present disclosure.

[0027] Figure 2 is a schematic view of a portion of a hydraulic system usable with the work machine shown in Figure 1 and including a variable displacement pump system.

[0028] Figure 3 is a schematic view of a portion of a hydraulic system usable with the work machine shown in Figure 1 and including a variable displacement system converted to operate as a fixed displacement system.

[0029] Figure 4 is a schematic view of a hydraulic system usable with the work machine shown in Figure 1 and including a variable displacement system converted to operate as a fixed displacement system. [0030] Figure 5 is a schematic view of a control valve assembly usable in the hydraulic system shown in Figure 4, the control valve assembly being in a first, neutral position.

[0031] Figure 6 is a schematic view of the control valve assembly shown in Figure 5, the control valve assembly being in a second position.

[0032] Figure 7 is a schematic view of the control valve assembly shown in Figure 5, the control valve assembly being in a third position.

[0033] Figure 8 is a cross-sectional view of the control valve assembly shown in Figure 4, the control valve assembly being in the first, neutral position.

[0034] Figure 9 is a cross-sectional view of the control valve assembly shown in Figure 4, the control valve assembly being in the second position.

[0035] Figure 10 is a cross-sectional view of the control valve assembly shown in Figure 4, the control valve assembly being in the third position.

[0036] Figure 11 is a cross-sectional view of a simplified version of the control valve assembly shown in Figure 4, with the compensator functions removed.

DETAILED DESCRIPTION

[0037] Various embodiments will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the appended claims.

Work Machine

[0038] As depicted at Figure 1, a work machine 1 is shown. The work machine 1 may be any type of work machine, for example a fire truck, fork lift, wheel loader, track loader, excavator, backhoe, bull dozer, fire truck or telehandler. As depicted, work machine 1 includes a work attachment 2 for performing a variety of lifting tasks associated with a load 3. In one embodiment, work machine 1 is a telehandler having a telescoping boom 4 that supports the work attachment 2 and stabilizers 9 for stabilizing the work machine 1 during lifting operations. In one embodiment, the work attachment 2 includes a pair of forks. However, one skilled in the art will appreciate that work attachment may be any hydraulically powered work implement.

[0039] Work machine 1 is also shown as including at least one drive wheel 5 and at least one steer wheel 6. In certain embodiments, one or more drive wheels 5 may be combined with one or more steer wheels 6. The drive wheels 5 are powered by an engine 7. Engine 7 is also configured to power a hydraulic system 10 including various circuits, such as a work circuit 12 and a steering circuit (not shown) of the work machine 10 via at least one hydraulic pump 14. In one embodiment, the hydraulic system 10 includes a pump 14 mechanically coupled to the engine 7, such as by an output shaft or a power take-off. In one embodiment, pump 14 is powered indirectly by the engine 7. The work circuit 10 actuates the work attachment 2 by operation of the pump 14 in cooperation with a number of hydraulic actuators 16 and control valves 22a, 22b. In one embodiment, the work machine 1 includes hydraulic actuators and valves for effectuating steering and propulsion, stabilizing, and for lifting, extending, tilting, and sideways motions of the work attachment 7. Although an example work machine 1 is shown and described, the disclosure is not limited to any particular work machine and is broadly applicable to any hydraulic system including actuators and a pump operated with loadsense control.

Hydraulic System

[0040] Referring to Figure 2, a portion of a hydraulic system 10 with a control valve 102 controlling flow to an actuator 16, and usable with the work machine 1 in Figure 1, is presented. As presented, the hydraulic system 10 of Figure 2 is a variable pump system in which a pump compensator maintains a margin value between the pump pressure P and the load sense pressure LS. In such a configuration, the pump 14 supplies flow, as per demand. The work section disclosed in Figure 2 can be referred to as a precompensated work section. [0041] Referring to Figure 3, a portion of hydraulic system 10 with a control valve 100 controlling flow to an actuator 16, and usable with the work machine 1 in Figure 1, is presented. The hydraulic system 10 of Figure 3 is similar to that shown in Figure 1, but is converted to be operable as a fixed displacement system. With such a configuration, the system is operable to disable the pump compensator such that the pump works in a fixed displacement mode. As shown, the pump pressure P and the load sense pressure LS short together. The work section disclosed in Figure 3 can be referred to as a noncompensated work section.

[0042] Referring to Figure 4, a hydraulic system 10 usable with the work machine 1 in Figure 1 is presented. As shown at Figure 4, the hydraulic system 10 can include multiple stacked work sections 5A, 5B, 5C in which a modular-type, single valve assembly construction is provided. Although three stacked work sections are shown, more or fewer may be provided. In one aspect, the work section 5A can be characterized as a post-compensated work section having a control valve assembly 104 configured for such operation, the work section 5B can be characterized as a non-compensated work section having a control valve assembly 100 configured for such operation, and the work section 5C can be characterized as a pre-compensated work section having a control valve assembly 102 configured for such operation. In one example, the work sections 5A, 5B, 5C are configured to be used in an Eaton CLS Load-Sensing Sectional Mobile Valve manufactured by Eaton Corporation of Cleveland, Ohio, USA. Other configurations are possible, such as configurations in which more or fewer postcompensated, non-compensated, and/or pre-compensated sections 5A, 5B, 5C are provided in varying combinations.

[0043] With reference to section 5B at Figure 4, it can be seen that ports A2, B2, an optional LS check valve in fluid communication with a control valve assembly 100 are presented. In one aspect, the control valve assembly 100 includes a first actuator first port A, a first actuator second actuator port B, a pump port P, a load sense port Ls, and a tank port T. As shown at Figures 5 to 7, the control valve assembly 100 can be operated into various positions by actuators 110, 112. The actuators 110, 112 may be, for example, solenoid or hydraulic type actuators. In one aspect, the control valve assembly 100 can include a ported body or sleeve 114 within which a spool 116 is operated between a first position (Figure 5), a second position (Figure 6), and a third position (Figure 7) to selectively place the pump P and tank T in fluid communication with the actuator ports A, B. In the first position, as shown at Figure 5, the control valve assembly 100 blocks flow between all of the ports A, B, P, Ls, T. In the second position, as shown at Figure 6, the control valve assembly 100 enables flow between the ports A, P and between the ports B, T, and also places the load sense port Ls in fluid communication with the ports A, P. In the third position, as shown at Figure 7, the control valve assembly 100 enables flow between the ports B, P and between the ports A, T, and also places the load sense port Ls in fluid communication with the ports B, P.

[0044] Referring to Figure 8, a cross-sectional view of the control valve assembly 100 is presented in a valve work section, wherein the control valve assembly 100 is in the first position. As illustrated, the control valve assembly 100 represents a stackable, noncompensated work section 121 of the hydraulic system 10 and is shown as including a main body 114 within which a main control spool 116 is disposed. In one aspect, the work section main body 114 can be provided with openings, for example openings or through- holes 129, for receiving connecting rods passing through multiple stacked work sections such that the work sections can be secured together, for example by fasteners threaded onto the rods extending through the openings 129. In the example presented, the control valve assembly 100 further includes pump pressure port 122, a B port 123, an A port 124, a meter-in control orifice 125, a meter-out control orifice 126, an LS gallery 127 that is common to all sections, a P-LS connection orifice (P-B) 128, a P-LS connection orifice (P-A) 129, a tank gallery 130, and a P-LS check valve 131, for example a spring-check valve, that functions to prevent flow in a direction from the LS gallery 127 towards the P gallery 122 while allowing flow in the opposite direction. In the first or neutral condition, the P and LS galleries are disconnected as all holes in the spool are isolated. Additionally, check valve 131 helps to prevent any back pressure from other sections to be fed into port 122.

[0045] In the example presented, the main body 114 can be provided with a section compensator section defining the LS gallery 127, wherein the section compensator is removed and replaced by the P-LS check valve 131. In one aspect, the LS check valve 131 can be provided with a movable valve portion 131a and a ported main body 131b, wherein the valve portion 131a is a spring check type valve received in porting of the main body 131b. In one aspect, the main body 131b has seals 131c which isolate the pump pressure at P, 122 from the LS gallery 127. In one aspect, the main body 131b the valve portion 131a is disposed between porting passageways 131c, 131d of the main body 131b such that the valve portion 131a operates to prevent flow in the direction from the passageway 13 Id to the passageway 131c while allowing flow in the opposite direction. As shown, the porting passageway 131c is in fluid communication with the P gallery 122 while the porting passageway 13 Id is in fluid communication with the LS gallery 127. Plugs 133, 135 can be provided at each end of the LS gallery 127 and can function to axially secure the LS check valve main body 131b within the LS gallery 127. The plugs 133, 135 can be provided with seals, for example, seals 133a, 135a to isolate the tank ports 130. In the neutral condition, the rest of the pre and post compensated sections can work as intended. It is also noted that the main body 114 can be specifically ported for use with the LS check valve 131 without communication ports to the pump and tank ports for non-compensated operation, for example as is shown at Figure 11.

[0046] Referring to Figure 9, a cross-sectional view of the control valve assembly 100 is presented, in which the control valve assembly is in the second position. As illustrated, when spool 12 is actuated to supply flow to port A 4, flow from pump port 2 passes through casting flow loop through the meter in control orifice 5 to the work port A 4. At the same time pump port pressure 2 is fed through P-LS orifice 9 into the check valve 11 and then fed into the LS gallery 7 that goes to the LS port connection on the pump in the inlet. As pump pressure is fed into the LS port of the pump both pressure levels become to that of the pump delivery pressure, making pump run in fixed displacement mode. This will intern makes this section work as normal non-compensated open center type directional control valve. All the available flow will be used to these types of sections and will work in low load high speed and high load low speed scenarios. At the same time flow from port B 3 will pass over meter out control orifice 6 and pass oil to tank port T. [0047] Referring to Figure 10, a cross-sectional view of the control valve assembly 100 is presented, in which the control valve assembly is in the third position. As illustrated, when spool 12 is actuated to supply flow to port B 3, flow from pump port 2 passes through casting flow loop through the meter in control orifice 5 to the work port B 3. At the same time pump port pressure 2 is fed through P-LS orifice 8 into the check valve 11 and then fed into the LS gallery 7 that goes to the LS port connection on the pump in the inlet. As pump pressure is fed into the LS port of the pump both pressure levels become to that of the pump delivery pressure, making pump run in fixed displacement mode. This will intern makes this section work as normal non-compensated open center type directional control valve. All the available flow will be used to these types of sections and will work in low load high speed and high load low speed scenarios. At the same time flow from port A 4 will pass over meter out control orifice 6 and pass oil to tank port T.

[0048] Referring to Figure 11, a cross-sectional view of a simplified casting design of the control valve assembly 100 shown at Figures 7 to 9 is presented. In this example, the compensator bore and all of the section compensator components are not provided or are removed, for example via machining and honing, and the body 114 is provided with simple machining with a passageway 127a receiving a ported plug 133 and the P-LS check valve 131, and is further provided with passageways 127a, 127b in fluid communication with the porting 127a which may form a portion of the load sense gallery 127. In the example shown, the P-LS check valve 131 is a spring-check valve received within porting 133b formed in the plug 133, wherein the P-LS check valve 131 allows for flow from the passageway 127b to the passageway 127a via additional porting 133c in the plug 133.

Electronic Control System

[0049] In one aspect, the work machine 1 and the components of the hydraulic system 10, such as the pump and control valve assembly or assemblies 100, and other related components can be operated by an electronic controller 50 (see Figure 1) with any desired number of inputs and outputs. The electronic control system 50 can include multiple controllers. For example, the control system 50 can include a system-level HFX programmable controller manufactured by Eaton Corporation of Cleveland, Ohio, USA; and an Eaton VSM controller which serves as an interface module and acts as a CAN gateway, a DC to DC power supply, and a supervisory controller for the hydraulic valve system. In one aspect, the control system 50 can also include valve assemblies 22a, 22b that are configured within an Eaton CMA valve which includes a CAN-Enabled electrohydraulic sectional mobile valve that utilizes pressure and position sensors, on board electronics, and advanced software control algorithms.

[0050] The control system 50 can include a processor and a non-transient storage medium or memory, such as RAM, flash drive or a hard drive. Memory is for storing executable code, the operating parameters, and the input from the operator user interface while processor is for executing the code. The control system 50 can also include transmitting/receiving ports, such as a CAN bus connection or an Ethernet port for two- way communication with a WAN/LAN related to an automation system and to interrelated controllers. A user interface may be provided to activate and deactivate the system, allow a user to manipulate certain settings or inputs to the control system 50, and to view information about the system operation.

[0051] The control system 50 typically includes at least some form of memory. Examples of memory include computer readable media. Computer readable media includes any available media that can be accessed by the processor. By way of example, computer readable media include computer readable storage media and computer readable communication media. Computer readable storage media includes volatile and nonvolatile, removable and non-removable media implemented in any device configured to store information such as computer readable instructions, data structures, program modules or other data. Computer readable storage media includes, but is not limited to, random access memory, read only memory, electrically erasable programmable read only memory, flash memory or other memory technology, compact disc read only memory, digital versatile disks or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and that can be accessed by the processor.

[0052] Computer readable communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” refers to a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, computer readable communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency, infrared, and other wireless media. Combinations of any of the above are also included within the scope of computer readable media.

[0053] The various embodiments described above are provided by way of illustration only and should not be construed to limit the claims attached hereto. Those skilled in the art will readily recognize various modifications and changes that may be made without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the disclosure.