Hydraulic fluid preheating using the driving control circuit

Abstract

This disclosure relates to hydraulic fluid preheating using a travel control circuit. According to an example embodiment, the hydraulic system may include a pump, a reservoir, an accumulator, a hydraulic cylinder, a travel control valve assembly, and a controller. The travel control valve assembly may include a fill valve, a discharge valve, and a head travel control valve. The controller may open the head travel control valve when the travel control feature has been activated, or open the fill valve if the travel control feature is not activated and hydraulic fluid preheating is to be performed.

Description

Technical Field

[0001] This invention generally relates to hydraulic systems. Embodiments of this disclosure relate to hydraulic circuits that can be used for ride control and hydraulic fluid warm-up features. Background Technology

[0002] Some machines include hydraulic systems, such as vehicles that can use hydraulic systems to move various components and perform tasks. Hydraulic systems on such machines operate more optimally when the hydraulic fluid is within a target temperature range, and less optimally when the hydraulic fluid is below that range. While the operation of a hydraulic system performing a task may incidentally heat the hydraulic fluid in the system, preheating features can be included to accelerate the preheating process and allow the hydraulic system to operate more optimally with less preheating delay.

[0003] Some machines with hydraulic systems may encounter loads on the hydraulic system or external forces on the machine, which can cause oscillations in the machine or hydraulic system, such as a vehicle bouncing on an uneven surface. The hydraulic system on such a machine may include a driving control feature that controls certain components of the hydraulic system (such as hydraulically connected hydraulic cylinders to an accumulator) to move selectively in a way that counteracts and dampens the oscillations experienced by the machine or hydraulic system. Summary of the Invention

[0004] Various aspects of the examples of this disclosure are set forth in the claims.

[0005] According to a first aspect of this disclosure, a hydraulic system may include a pump, a reservoir, an accumulator, a hydraulic cylinder, a travel control valve assembly, and a controller. The travel control valve assembly may include a fill valve, a discharge valve, and a head travel control valve. The fill valve includes a fill valve inlet and a fill valve outlet. When the fill valve is in the open position, the fill valve inlet and outlet may be hydraulically connected, and when the fill valve is in the closed position, the fill valve inlet and outlet may be hydraulically disconnected. The fill valve inlet may be hydraulically connected to the pump to receive hydraulic fluid from the pump. The fill valve outlet may be hydraulically connected to the accumulator. The discharge valve may include a discharge valve inlet and a discharge valve outlet, which are hydraulically connected when the discharge valve is in the open position and hydraulically disconnected when the discharge valve is in the closed position. The discharge valve inlet may be hydraulically connected to the fill valve outlet and the accumulator, and the discharge valve outlet may be hydraulically connected to the reservoir to supply hydraulic fluid to the reservoir. The head travel control valve may include a head travel control valve inlet and a head travel control valve outlet. When the head travel control valve is in the open position, the inlet and outlet are hydraulically connected; when the head travel control valve is in the closed position, the inlet and outlet are hydraulically disconnected. The head travel control valve inlet may be hydraulically connected to a hydraulic cylinder, and the head travel control valve outlet may be hydraulically connected to an accumulator.

[0006] The controller can communicate with the travel control valve assembly and includes a processor and a reservoir storing instructions, wherein the processor is configured to execute the instructions to: determine whether a travel control feature has been activated; move the head travel control valve to the open position in response to determining that the travel control feature has been activated; determine whether to perform hydraulic fluid preheating; and move the filling valve to the open position in response to determining that the travel control feature has not been activated and that hydraulic fluid preheating is to be performed.

[0007] The above and other features will become apparent from the following description and accompanying drawings. Attached Figure Description

[0008] For a detailed description of the accompanying drawings, please refer to the drawings themselves.

[0009] Figure 1 This is a left view of the machine, which in this embodiment is a wheeled loader working vehicle.

[0010] Figure 2 This is a schematic diagram of the machine's connecting rods and hydraulic system.

[0011] Figure 3This is a hydraulic schematic diagram of a part of the hydraulic system of a machine in its first state, including hydraulic circuits for travel control and preheating features.

[0012] Figure 4 This is a hydraulic schematic diagram of a part of the hydraulic system of a machine in its second state, including hydraulic circuits for travel control and preheating features.

[0013] Figure 5 This is a hydraulic schematic diagram of a part of the hydraulic system of a machine in its third state, including hydraulic circuits for driving control and preheating features.

[0014] Figure 6 This is a flowchart of the control system of a hydraulic system. Detailed Implementation

[0015] By referring to the attached diagram Figures 1 to 6 To understand the subject matter of this disclosure, at least one exemplary embodiment is provided, wherein the same reference numerals are used to indicate the same elements in all the figures.

[0016] Figure 1 This is a left view of the work vehicle 100. The work vehicle 100 is illustrated as a wheeled loader in this embodiment, but it can also be any number of other work vehicles with a hydraulic system, such as a backhoe loader or a skid steer loader (to name just two examples). The work vehicle 100 includes a chassis 102 to provide structure and support for the components of the work vehicle 100. In this embodiment, the work vehicle 100 travels along the ground via four wheels 104, but in other embodiments, the work vehicle may use other ground-engaging means, such as tracks. Additionally, the number of ground-engaging means may differ from the exemplary embodiments shown in the figures and described herein. At the front end of the work vehicle 100 is a link 106, which includes a plurality of rigid members pivotally connected to each other and connected at one end to the chassis 102 and at the opposite end to a work tool 108, which in this embodiment is a bucket. Linkage 106 is actuated by hydraulic system 110, which may include (but is not limited to) multiple hydraulic pumps, cylinders, valves, and plumbing, wherein one of the two boom cylinders 112 and the bucket cylinder 114 are... Figure 1 As can be seen in the text.

[0017] Figure 2This is a schematic diagram of a portion of the connecting rod 106, a portion of the hydraulic system 110 including the boom cylinder 112 and other components, and the working tool 108. The hydraulic system 110 includes a valve block 116 hydraulically connected to the boom cylinder 112, allowing the valve block 116 to control the flow of hydraulic fluid into and out of the head and rod ends of the boom cylinder 112. The valve block 116 is also hydraulically connected to an accumulator 118, a hydraulic pump 120 (in this embodiment, a variable displacement load-sensing pump), and a hydraulic reservoir 122. As shown in later figures, the valve block 116 allows for travel control features, in which hydraulic fluid moves between the boom cylinder 112 and the accumulator 118, allowing the boom cylinder 112 to extend and retract in a restricted manner, and to move the connecting rod 106 and the working tool 108 relative to the chassis 102. This restricted movement allows the working tool 108, the linkage 106, and the mass of the payload in the working tool 108 to float relative to the chassis 102, and thus serve as a dynamic counterweight to counteract and thereby dampen the vibrations of the working vehicle 100 that may be caused by uneven surface conditions on which the working vehicle 100 travels or other external forces acting on the working vehicle 100.

[0018] Valve block 116 includes multiple hydraulic ports through which it is hydraulically connected to other hydraulic components. Valve block 116 is hydraulically connected to the head end of boom cylinder 112 via line 124 and to the rod end of boom cylinder 112 via line 126. Valve block 116 is hydraulically connected to accumulator 118 via line 128 and to reservoir 122 via line 130. Valve block 116 is hydraulically connected to the output or operating port of pump 120 via line 132 and to the load sensing port of pump 120 via line 134.

[0019] Figure 3 This is a hydraulic schematic illustrating certain components within valve block 116 and how valve block 116 is connected via plumbed to other components in hydraulic system 110. Valve block 116 receives pressurized hydraulic fluid from pump 120, which draws hydraulic fluid from reservoir 122 and supplies it to valve block 116 via line 132. Within valve block 116, this pressurized hydraulic fluid is received by charging valve 136. Charging valve 136 includes inlet 136a and outlet 136b. When charging valve 136 is in a certain position... Figure 3 When in the closed position as shown, inlet 136a and outlet 136b are hydraulically disconnected, but when filling valve 136 is in the closed position as shown... Figure 4 and Figure 5In the open position shown, inlet 136a and outlet 136b are hydraulically connected. The filling valve 136 can be actuated between the closed and open positions by a solenoid 136c, which in turn can be actuated by applying current from a controller 138 electrically connected to it. For readability, the electrical connections between the controller 138 and the solenoid 136c, as well as other solenoids, sensors, and electrical components, are shown in [details omitted]. Figures 3 to 5 Not shown in the image.

[0020] The outlet 136b of the filling valve 136 is hydraulically connected to the line 128, which in turn connects to the accumulator 118. Thus, the state or position of the filling valve 136 controls the filling of the accumulator 118 by allowing or disallowing the pump 120 to draw hydraulic fluid from the reservoir 122 and pump it into the accumulator 118. When the filling valve 136 controls the filling of the accumulator 118 via the pump 120, the accumulator 118 is hydraulically connected to multiple other components in the valve block 116, such that the net filling or discharging effect of the accumulator 118 is controlled by multiple components, pressure, and flow rate.

[0021] Accumulator 118 is hydraulically connected to both the outlet 136b of fill valve 136 and the inlet 140a of discharge valve 140 within valve block 116. In other words, the outlet 136b of fill valve 136 is hydraulically connected to both the inlet 140a of discharge valve 140 and accumulator 118. Discharge valve 140 includes inlet 140a and outlet 140b, and when discharge valve 140 is in a certain position... Figure 3 and Figure 4 When in the closed position as shown, inlet 140a and outlet 140b are hydraulically disconnected, but when the discharge valve 140 is in the closed position as shown... Figure 5 In the open position shown, inlet 140a and outlet 140b are hydraulically connected. The drain valve 140 can be actuated between the closed and open positions by a solenoid 140c, which is electrically connected to a controller 138. The outlet 140b of the drain valve 140 is hydraulically connected to line 130, which in turn connects to reservoir 122.

[0022] Line 130 and the resulting reservoir 122 are also hydraulically connected to the outlet 142b of the boom travel control valve 142. The inlet 142a of the boom travel control valve 142 is hydraulically connected to line 126, which in turn connects to the boom end of the boom cylinder 112. When the boom travel control valve 142 is in the position... Figures 3 to 5In the closed position, inlet 142a and outlet 142b are hydraulically disconnected, while inlet 142a and outlet 142b are hydraulically connected when the boom travel control valve 142 is in the open position. The boom travel control valve 142 can be actuated between the closed and open positions by solenoid 142c, which is actuated by controller 138 electrically connected thereto. When the travel control feature of the hydraulic system 110 is activated, solenoid 142c moves the boom travel control valve 142 from the closed position to the open position, thereby allowing hydraulic fluid to flow between the rod side of the boom cylinder 112 and the reservoir 122. This flow of hydraulic fluid avoids trapping hydraulic fluid on the rod side of the boom cylinder 112, and thus allows the boom cylinder 112 to extend or retract as required by the travel control feature.

[0023] Valve block 116 also includes a head travel control valve 144. The inlet 144a of the head travel control valve 144 is hydraulically connected to line 124, thereby hydraulically connecting the head travel control valve 144 to the head side of the boom cylinder 112. The outlet 144b of the head travel control valve 144 is hydraulically connected to line 128 (and thus to the accumulator 118), as well as the outlet 136b of the fill valve 136 and the inlet 140a of the discharge valve 140. When the head travel control valve 144 is in such a state... Figures 3 to 5 In the closed position, inlet 144a and outlet 144b are hydraulically disconnected, but when the head travel control valve 144 is in the open position, inlet 144a and outlet 144b are hydraulically connected. The head travel control valve 144 can be actuated between the closed and open positions by solenoid 144c, which is actuated by controller 138 electrically connected thereto. More specifically, actuation of solenoid 144c displaces the first spool valve 144d, thereby changing the first pilot pressure on the second spool valve 144e from being supplied by line 124 (head side of boom cylinder 112) to being supplied by reservoir 122. The second spool valve 144e has a first pilot pressure for closing the second spool valve 144e and a second pilot pressure supplied by line 124 for opening the second spool valve 144e on the opposite side. Therefore, if the pressure in the head side of the boom cylinder 112 is sufficient, the actuation of the solenoid 144c allows the second spool valve 144e to move to the open position. Although in Figures 3 to 5 This arrangement of the head travel control valve 144 is illustrated, but alternative embodiments can achieve the same operation using alternative arrangements.

[0024] Head travel control valve 144 is used to selectively allow hydraulic fluid to flow between the head side of boom cylinder 112 and accumulator 118, and thus (together with lever travel control valve 142) selectively activate travel control features. When both head travel control valve 144 and lever travel control valve 142 are activated (i.e., the respective solenoids 142c and 144c are actuated by controller 138 to move the valves to the open position), and thus the travel control features are activated, hydraulic fluid can flow between the lever side of boom cylinder 112 and reservoir 122, and hydraulic fluid can flow between the head side of boom cylinder 112 and accumulator 118. These two fluid flows allow boom cylinder 112 to extend and retract as needed to allow relative movement between link 106 (and the attached work tool 108) and chassis 102 of work vehicle 100.

[0025] The hydraulic system 110 may also include multiple pressure sensors to monitor hydraulic pressure at certain points in the hydraulic circuit. Such sensors may include: a headside sensor 146 monitoring hydraulic pressure on the headside of the boom cylinder 112; a load sensing sensor 148 monitoring hydraulic pressure on the load sensing line 134; and an accumulator sensor 150 monitoring hydraulic pressure in the accumulator 118. Each of these sensors is electrically connected to a controller 138 such that signals indicating these pressures can be monitored by the controller 138. In an alternative embodiment, some or all of these pressure sensors may be configured as a combined pressure and temperature sensor, which can indicate hydraulic fluid pressure and temperature to the controller 138.

[0026] Valve block 116 also includes an orifice 152, which may also be referred to as a hydraulic orifice or flow restriction. Orifice 152 hydraulically connects the outlet 136b of filler valve 136 to reservoir 122 via the same hydraulic line 130 as the outlet 142b of lever travel control valve 142 and the outlet 140b of drain valve 140. This orifice may have an appropriate size, such as a diameter of 0.030 inches, to ensure that hydraulic fluid flowing through it does not interfere with the function of filler valve 136. In other embodiments, the orifice may have different equivalent hydraulic diameters, for example, in the range of 0.010 inches to 0.100 inches. A check valve may also be appropriately provided within valve block 116 to ensure that fluid and pressure are not gradually discharged from accumulator 118 through orifice 152.

[0027] Figure 4This is a hydraulic schematic illustrating a valve block 116 having a fill valve 136 in the open position and a discharge valve 140 in the closed position. In this configuration, a pump 120 supplies pressurized hydraulic fluid to the valve block 116 via a line 132. With the fill valve 136 in the open position, the hydraulic fluid received by the valve block 116 can pass through the fill valve 136, where it can fill an accumulator 118 and leak through an orifice 152. After the accumulator 118 is filled, the fill valve 136 remains open to allow pressurized hydraulic fluid to continue leaking through the orifice 152 and returning to the reservoir 122. As the hydraulic fluid changes from high pressure upstream of the orifice 152 to low pressure downstream, this leakage flow generates heat and returns the heated fluid to the reservoir 122. This leakage flow also allows the hydraulic fluid to circulate between the reservoir 122, the pump 120, and the valve block 116, thereby distributing the heated hydraulic fluid to these systems. The size of orifice 152 can be selected to balance the heat generated by the leakage flow with other performance considerations of valve block 116 and pump 120.

[0028] Figure 5 This is a hydraulic schematic illustrating a valve block 116 with a fill valve 136 in the open position and a drain valve 140 in the open position. In this configuration, a pump 120 supplies pressurized hydraulic fluid to the valve block 116 via line 132. With the fill valve 136 and drain valve 140 in the open position, the hydraulic fluid received by the valve block 116 can pass through the fill valve 136 and drain valve 140 and exit the valve block 116 via line 130 to reach the reservoir 122. As the hydraulic fluid flows from the pump 120 through the hydraulic system 110 to the reservoir 122, the pressure drop experienced by the hydraulic fluid is converted into heat, thereby preheating the hydraulic fluid when it returns to the reservoir 122. This flow path also allows the hydraulic fluid to circulate between the reservoir 122, the pump 120, and the valve block 116, thereby distributing the heated hydraulic fluid to these systems.

[0029] Figures 3 to 5 This illustrates how the configuration of hydraulic system 110 can be used to provide preheating features to a hydraulic system with driving control characteristics without adding a dedicated preheating valve or orifice. This can allow for the provision of preheating features for certain applications with reduced cost or complexity. Figures 4 to 5 It also illustrates how the hydraulic system 110 allows for different preheating operations using the same hardware, wherein... Figure 4An example of a preheating operation is illustrated, which allows for the filling of the accumulator 118 while heating the hydraulic fluid in the hydraulic system 110 using only the leakage path through the orifice (orifice 152). Conversely, if the filling valve 136, the drain valve 140, and the internal connection passages are appropriately sized and the pump 120 has the capability to allow the hydraulic system 110 to be heated more quickly but not to allow the accumulator 118 to be filled, then... Figure 5 Allows for higher flow leakage paths. Depending on the application or specific needs of the hydraulic system 110 during preheating time, the controller 138 can select the most appropriate preheating operation.

[0030] Figure 6 This is a flowchart illustrating a control system 200 operating on controller 138. Control system 200 controls the travel control and preheating features of hydraulic system 110. In step 202, controller 138 determines whether travel control is enabled; if yes, it proceeds to step 204; otherwise, it proceeds to step 214. Controller 138 determines whether travel control is enabled by monitoring whether the operator of work vehicle 100 has already enabled travel control, for example, by actuating a switch in the operator's station. However, in alternative embodiments, other methods may be used to enable or disable the travel control features of work vehicle 100 (e.g., always enabled, remotely enabled, enabled when certain speed and load conditions are met). Additionally, in alternative embodiments, if preheating is detected (e.g., based on the temperature of the hydraulic fluid), controller 138 may disable travel control in step 202 to perform preheating, or controller 138 may disable travel control only under certain conditions (e.g., if the machine is parked or traveling below a certain speed) to perform preheating. Therefore, controller 138 can determine whether the driving control feature is passively enabled (by checking whether driving control is already enabled) or actively enabled (by disabling the driving control feature if it is currently enabled).

[0031] In step 204, controller 138 determines whether the pressure between accumulator 118 and boom cylinder 112 (specifically, the head side of boom cylinder 112) is balanced. If so, proceed to step 206; otherwise, proceed to step 212. Controller 138 determines whether the pressure is balanced by comparing signals it receives directly or indirectly from head side sensor 146 (sensing pressure in the head side of boom cylinder 112) and accumulator sensor 150 (sensing pressure in accumulator 118). If the signals from both sensors indicate the same pressure or pressure within each other's threshold amount (e.g., 5 bar), controller 138 determines that the pressure is balanced.

[0032] In step 206, controller 138 determines whether the travel control feature of hydraulic system 110 is active. If yes, it proceeds to step 208; otherwise, it proceeds to step 214. Controller 138 can determine whether travel control is active by monitoring whether the work vehicle 100 is traveling above a threshold speed, whether there is a load on the work tool 108, whether the operator has forced travel control into an active state, other factors, or a combination of these factors. In an alternative embodiment, for example, if preheating is detected (e.g., based on the temperature of the hydraulic fluid), controller 138 can deactivate travel control in step 206 to perform preheating, or controller 138 can disable travel control only under certain conditions (e.g., if the machine is parked or traveling below a certain speed) to perform preheating. Therefore, controller 138 can determine whether to perform hydraulic fluid preheating in response to determining that the travel control feature has not been passively (by checking that the travel control feature is already inactive) or actively (by deactivating the travel control feature if it is currently active). The control system and algorithm may be included in the control system 200, or alternatively may be separate from the control system 200, which disables driving control features to enable warm-up and thus allows the control system 200 to proceed from step 206 to step 214.

[0033] In step 208, in response to determining that driving control is active, controller 138 shuts off or keeps the current to solenoid 136c of fill valve 136 and solenoid 140c of exhaust valve 140. As the current to their respective solenoids is shut off, each of fill valve 136 and exhaust valve 140 will shift to or remain in the closed position.

[0034] In step 210, controller 138 turns on or maintains current to solenoid 142c of boom travel control valve 142 and solenoid 144c of head travel control valve 144. As current is turned on to their respective solenoids, each of boom travel control valve 142 and head travel control valve 144 will shift to or remain in the open position. Actuation of solenoid 142c directly actuates boom travel control valve 142 to the open position, where solenoid 142c hydraulically connects the boom side of boom cylinder 112 to reservoir 122 via line 130, thereby allowing hydraulic fluid to flow between the two components. Actuation of solenoid 144c switches the pressure source for the first pilot port of head travel control valve 144 from supply to the head side of boom cylinder 112 to supply to reservoir 122, thus unbalancing head travel control valve 144. This causes the pressure in the head side of boom cylinder 112 to exceed a threshold pressure, which will tend to shift head travel control valve 144 from the closed position to the open position. By actuating solenoid 144c, controller 138 thereby places head travel control valve 144 in a state where sufficient pressure on the head side of boom cylinder 112 will shift head travel control valve 144 to allow hydraulic flow between the head side of boom cylinder 112 and accumulator 118. After step 210, the travel control features of hydraulic system 110 are activated and operated.

[0035] In step 212, if a pressure imbalance between the accumulator 118 and the head side of the boom cylinder 112 is determined in step 204, the controller 138 adjusts the fill valve 136 and the discharge valve 140 to balance the pressure. If the controller 138 senses that the pressure on the head side of the boom cylinder 112 is greater than the pressure in the accumulator 118, for example, by a threshold amount, the controller 138 actuates the fill valve 136 to the open position (or holds it in the open position) and actuates the discharge valve 140 to the closed position (or holds it in the closed position). Opening the fill valve 136 or keeping the fill valve 136 open allows hydraulic fluid to flow from the pump 120 through line 132 into the accumulator 118, which tends to increase the pressure in the accumulator 118 and thereby balance the higher pressure in the accumulator 118 with the higher pressure on the head side of the boom cylinder 112. Closing or keeping the drain valve 140 closed prevents or restricts the flow of hydraulic fluid from the accumulator 118 to the reservoir 122 via the line 130. This tends to reduce the pressure in the accumulator 118 and thus prevent it from rising to balance the pressure on the head side of the boom cylinder 112.

[0036] Alternatively, if the controller 138 senses that the pressure on the head side of the boom cylinder 112 is less than the pressure in the accumulator 118, for example, less than a threshold amount, the controller 138 actuates the fill valve 136 to the closed position and the drain valve 140 to the open position. Closing the fill valve 136 prevents hydraulic fluid from flowing from the pump 120 to the accumulator 118, while opening the drain valve 140 allows hydraulic fluid to flow from the accumulator 118 to the reservoir 122, thereby draining the accumulator 118 and reducing its pressure to balance it with the pressure on the head side of the boom cylinder 112.

[0037] In step 214, if it is determined that driving control is not enabled (step 202) or not activated (step 206), controller 138 determines whether to perform hydraulic fluid preheating. If yes, proceed to step 216; otherwise, proceed to step 202. Controller 138 may determine this in a variety of ways or using a combination of factors. As an example, if the sensor is capable of sensing both pressure and temperature, controller 138 may use head-side sensor 146 to monitor the temperature of the hydraulic fluid at a point in the system and perform preheating if that temperature is below a target temperature (e.g., 50°F). As another example, controller 138 may perform preheating if the work vehicle 100 has just started after an inactive period (e.g., 30 minutes). As yet another example, controller 138 may perform preheating if the work vehicle 100 has just started and the ambient temperature is below a threshold (e.g., 50°F). As another example, controller 138 can perform preheating after weighting multiple factors such as sensed hydraulic fluid temperature, ambient temperature, and the recent activity level of work vehicle 100.

[0038] In step 216, controller 138 actuates fill valve 136 to the open position. This allows hydraulic fluid to flow from pump 120 through line 132 to outlet 136b of fill valve 136. Pressurized hydraulic fluid leaks from outlet 136b of fill valve 136 through orifice 152 to reach line 130 and proceed to reservoir 122. As pressurized hydraulic fluid leaks through orifice 152, heat is generated by the resulting pressure drop in the hydraulic fluid, and the heated hydraulic fluid then returns to reservoir 122, where its heat can be distributed to other hydraulic fluid in the work vehicle 100. The equivalent orifice diameter of orifice 152, or the diameter of a circular orifice with the same flow resistance, can be selected to achieve the desired heating amount for this preheating feature while also satisfying other performance objectives of valve block 116. Figure 3 In the illustrated embodiment, orifice 152 has a diameter of 0.030 inches, but in some alternative embodiments of valve block 116, this can be a diameter between 0.010 inches and 0.100 inches, which can meet the performance requirements of other components within valve block 116.

[0039] In step 218, controller 138 determines whether to perform faster preheating. If yes, it proceeds to step 220; otherwise, it proceeds to step 202. Similar to step 214, controller 138 can make this determination in various ways or using a combination of factors. However, in step 218, controller 138 can utilize a higher threshold or cutoff value to determine whether to perform faster preheating. As an example, if the hydraulic fluid is below a first temperature (e.g., 50°F), controller 138 can determine in step 214 to perform preheating of the hydraulic fluid, but if the hydraulic fluid is below a second temperature (e.g., 0°F), controller 138 can determine in step 218 that faster preheating will be performed, where the second temperature is lower than the first temperature. As other examples, if the work vehicle 100 is idle, if the operator of the work vehicle 100 commands the work vehicle 100 such as by switching or inputting a button, or if the hydraulic functions on the work vehicle 100 are idle, controller 138 can determine that faster preheating should be performed. In another example, regardless of the process by which controller 138 enters the faster preheating mode, if controller 138 detects the use of hydraulic functions on the work vehicle 100 (including by sensing pressure, flow, or movement of hydraulically driven elements such as tools), controller 138 may exit the faster preheating mode.

[0040] In step 220, controller 138 actuates drain valve 140 to the open position. Combined with the opening or holding of fill valve 136 in step 216, this allows hydraulic fluid to flow from pump 120 through fill valve 136 and drain valve 140 to reservoir 122. As the hydraulic fluid travels this path, the pressure drop is converted into heat, and the heated hydraulic fluid is deposited in reservoir 122, where it can circulate through other hydraulic circuits.

[0041] exist Figures 3 to 6 In the illustrated embodiment, the hydraulic system 110 has a two-stage warming feature. The first stage provides warming due to the hydraulic flow through orifice 152, and the second stage provides additional warming due to the hydraulic flow through drain valve 140, which has a smaller flow limit, thereby allowing greater heat generation assuming sufficient flow capacity from pump 120. In an alternative embodiment, only one of these two flow paths may be provided, or both paths may be provided, but they may be activated under different conditions according to different instructions on controller 138.

[0042] As used herein, "controller" is intended to be used in accordance with how those skilled in the art use the term and refers to a computing component having processing, storage, and communication capabilities. A "controller" is used to execute (i.e., stored on a storage device or received via communication capabilities) instructions to control or communicate with one or more other components. In some embodiments, a controller may also be referred to as a control unit, vehicle control unit (VCU), engine control unit (ECU), transmission control unit (TCU), or electrical controller. In some embodiments, a controller may be configured to receive input signals of various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals) and output command or communication signals of various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals).

[0043] for Figures 3 to 6 In the illustrated embodiment, controller 138 (also referred to as vehicle control unit (VCU), control unit, control module, computing device, etc.) can communicate with other components on the work vehicle 100, such as hydraulic components (e.g., valve block 116), electrical components (e.g., solenoid 136c, accumulator sensor 150), and operator input sections within the operator station of the work vehicle 100. Controller 138 can be electrically connected to these other components via wiring harnesses, enabling the transmission of messages, commands, and power between controller 138 and the other components. Although controller 138 is referred to in the singular, in alternative embodiments, the configuration and functionality described herein may be divided into multiple controllers using techniques known to those skilled in the art.

[0044] Although the terms “inlet” and “outlet” are used herein and may indicate the most common direction of hydraulic flow in some embodiments, in other embodiments or certain applications, hydraulic fluid may flow into or out of the valve’s inlet or outlet.

[0045] Without limiting the scope, interpretation, or application of the claims that appear below in any way, the technical effect of one or more exemplary embodiments disclosed herein is to add a hydraulic fluid preheating feature to a hydraulic circuit with driving control features without additional components and without affecting the driving control features. Another technical effect of one or more exemplary embodiments disclosed herein is a hydraulic circuit and its controller that includes two hydraulic preheating paths that can be selectively engaged in certain circumstances.

[0046] As used herein, “for example” is used to list examples in a non-exhaustive manner and has the same meaning as alternative illustrative phrases such as “including,” “including but not limited to,” and “including but not limited to.” As used herein, unless otherwise limited or modified, a list of elements separated by a conjunction (e.g., “and”) and preceded by the phrase “one or more,” “at least one,” “at least,” or a similar phrase indicates a configuration or arrangement that may include individual elements of the list or any combination thereof. For example, “at least one of A, B, and C” and “one or more of A, B, and C” each mean only A, only B, only C, or any combination of two or more of A, B, and C (A and B, A and C, B and C, or A, B, and C). As used herein, the singular forms “a,” “one,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. Furthermore, the terms “including,” “comprise,” and similar phrases are intended to specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0047] While this disclosure has been illustrated and described in detail in the accompanying drawings and the foregoing description, such illustration and description are not restrictive in nature. It should be understood that exemplary embodiments have been shown and described, and protection is intended for all changes and modifications falling within the spirit of this disclosure. Alternative embodiments of this disclosure may not include all the features described, but will still benefit from at least some of the advantages of these features. Those skilled in the art can devise their own implementations that combine one or more features of this disclosure and fall within the spirit and scope of the appended claims.

Claims

1. A hydraulic system (110), the hydraulic system (110) comprising: Pump (120); Liquid reservoir (122); accumulator (118); Hydraulic cylinder (112); A driving control valve assembly (116), the driving control valve assembly (116) comprising: A filling valve (136) includes a filling valve inlet (136a) and a filling valve outlet (136b). When the filling valve (136) is in the open position, the filling valve inlet (136a) and the filling valve outlet (136b) are hydraulically connected, and when the filling valve (136) is in the closed position, the filling valve inlet (136a) and the filling valve outlet (136b) are hydraulically disconnected. The filling valve inlet (136a) is hydraulically connected to the pump (120) to receive hydraulic fluid from the pump (120), and the filling valve outlet (136b) is hydraulically connected to the accumulator (118). A discharge valve (140) having a discharge valve inlet (140a) and a discharge valve outlet (140b), wherein when the discharge valve (140) is in the open position, the discharge valve inlet (140a) and the discharge valve outlet (140b) are hydraulically connected, and when the discharge valve (140) is in the closed position, the discharge valve inlet (140a) and the discharge valve outlet (140b) are hydraulically disconnected. The discharge valve inlet (140a) is hydraulically connected to the filling valve outlet (136b) and the accumulator (118), and the discharge valve outlet (140b) is hydraulically connected to the reservoir (122) to provide hydraulic fluid to the reservoir (122); and A head travel control valve (144) having a head travel control valve inlet (144a) and a head travel control valve outlet (144b) is hydraulically connected when the head travel control valve (144) is in the open position, and hydraulically disconnected when the head travel control valve (144) is in the closed position. The head travel control valve inlet (144a) is hydraulically connected to the hydraulic cylinder (112), and the head travel control valve outlet (144b) is hydraulically connected to the accumulator (118). A controller (138) communicating with the driving control valve assembly (116), the controller (138) including a processor and a reservoir storing instructions, wherein the processor is configured to execute the instructions to perform the following operations: Determine whether the driving control features have been activated; In response to determining that the driving control feature has been activated, the head driving control valve (144) is moved to the open position; Determine whether to perform hydraulic fluid preheating; and In response to determining that the driving control feature is not activated and that hydraulic fluid preheating is about to be performed, the filling valve (136) is moved to the open position.

2. The hydraulic system according to claim 1, wherein, The driving control valve assembly (116) also includes a hydraulic port (152) via which the filler valve outlet (136b) is hydraulically connected to the reservoir (122), wherein the controller (138) is further configured to hold the discharge valve (140) in the closed position in response to determining that the driving control feature is not activated and that hydraulic fluid preheating is about to be performed.

3. The hydraulic system according to claim 1, wherein, The controller (138) is also configured to move the discharge valve (140) to the open position in response to determining that the driving control feature is not activated and that hydraulic fluid preheating is about to be performed.

4. The hydraulic system according to claim 1, further comprising: An accumulator pressure sensor (150) is configured to measure the pressure of the accumulator (118) and communicates with the controller (138). as well as A cylinder pressure sensor (146) is configured to measure the pressure in the head end of the hydraulic cylinder (112), and the cylinder pressure sensor (146) communicates with the controller (138). The controller (138) is further configured to: Determine whether the driving control feature has been enabled; The pressure in the accumulator (118) is compared with the pressure in the head end of the hydraulic cylinder (112); In response to determining that the driving control feature has been activated and in response to the sensed pressure in the accumulator (118) being less than the sensed pressure in the hydraulic cylinder (112), the filling valve (136) is moved to the open position; and In response to determining that the driving control feature has been activated and in response to the sensed pressure in the accumulator (118) being greater than the sensed pressure in the hydraulic cylinder (112), the discharge valve (140) is moved to the open position.

5. The hydraulic system according to claim 4, wherein, The driving control valve assembly (116) also includes a hydraulic port (152) via which the filler valve outlet (136b) is hydraulically connected to the reservoir (122), wherein the controller (138) is further configured to move the filler valve (136) to the open position and hold the drain valve (140) in the closed position in response to determining that hydraulic fluid preheating is to be performed.

6. The hydraulic system according to claim 4, wherein, The controller (138) is also configured to move the fill valve (136) to the open position and the discharge valve (140) to the open position in response to determining that hydraulic fluid preheating is to be performed.

7. The hydraulic system according to claim 4, wherein, The controller (138) is also configured to move at least one of the fill valve (136) and the discharge valve (140) to the closed position in response to determining that the driving control feature has been activated.

8. The hydraulic system according to claim 1, further comprising: An accumulator pressure sensor (150) is configured to measure the pressure of the accumulator (118) and communicates with the controller (138). as well as A cylinder pressure sensor (146) is configured to measure the pressure in the head end of the hydraulic cylinder (112), and the cylinder pressure sensor (146) communicates with the controller (138). The controller (138) is further configured to perform the following operations: Determine whether the driving control feature has been enabled; The pressure in the accumulator (118) is compared with the pressure in the head end of the hydraulic cylinder (112); In response to determining that the driving control feature has been enabled and in response to the comparison, the filling valve (136) is moved to the open position.

9. The hydraulic system according to claim 8, wherein, The controller (138) is also configured to move the filling valve (136) to the open position in response to determining that the driving control feature has been enabled and in response to determining that the pressure of the accumulator (118) is greater than a threshold lower than the pressure at the head end of the hydraulic cylinder (112).

10. The hydraulic system according to claim 1, wherein, The controller (138) is also configured to determine whether to perform hydraulic fluid preheating based on the temperature of the hydraulic fluid.

11. The hydraulic system according to claim 1, wherein, The pump (120) is a load-sensing pump.

12. The hydraulic system according to claim 2, wherein, The hydraulic orifice (152) has an equivalent orifice diameter of 0.010 inches to 0.100 inches.

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