Liquid supply system of wheel loader, control method and wheel loader

Abstract

The invention discloses a wheel loader liquid supply system, a control method and a wheel loader, the wheel loader liquid supply system comprises an engine controller, a working pump and a stop valve, the stop valve is connected to a liquid outlet of the working pump, and the working pump provides hydraulic oil for a loader working system; the cut-off valve cuts off or connects an oil path from the working pump to the working system of the loader according to the rotating speed of the engine and the rotating speed change trend of the engine. In the liquid supply system of the wheel loader, the cut-off valve is additionally arranged to cut off or connect an oil liquid path from the working pump to the working system of the loader, so that the load of the engine is reduced, and the probability that the engine is prone to flameout due to insufficient power under a high-load working condition (such as pressure building) or a plateau oxygen-deficient environment is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of loaders, and particularly relates to a liquid supply system for a wheel loader, a control method, and a wheel loader. Background Art

[0002] Currently, loaders are widely used in sand and gravel plants, mixing plants, railways, highways, mines, metallurgy and other fields, mainly for the shoveling, loading and unloading, transportation of bulk materials, and light excavation operations such as native soil. Due to its advantages such as fast operation speed, high efficiency, good mobility, and convenient operation, the loader has become one of the core equipment for earthwork construction in construction machinery.

[0003] However, the existing hydraulic systems of loaders generally adopt a fixed-displacement pump oil supply scheme, which is mainly divided into two forms: Fixed-displacement single-pump system: The steering system and the working system share the same hydraulic pump, with a simple structure; Fixed-displacement double-pump confluence system: After the steering pump gives priority to meeting the steering demand, the remaining flow is confluent with the working pump through the EF port of the priority valve and supplied to the working hydraulic system.

[0004] However, the above-mentioned schemes have significant defects: the engine is prone to stalling when the engine matching is insufficient. When the displacement of the engine matched by the whole machine is small or the low-speed torque is insufficient, in high-load working conditions (such as pressure holding) or high-altitude oxygen-deficient environments, the engine is extremely prone to stalling due to insufficient power, which not only affects the continuity of operation but also reduces the reliability of the whole machine. Summary of the Invention

[0005] One of the purposes of the present invention is to disclose a liquid supply system for a wheel loader. By adding a cut-off valve, the cut-off valve cuts off or conducts the oil passage from the working pump to the working system of the loader according to the engine speed and the trend of engine speed change, reducing the load of the engine and reducing the probability of engine stalling due to insufficient power in high-load working conditions (such as pressure holding) or high-altitude oxygen-deficient environments.

[0006] To achieve the above purpose, the present invention discloses a liquid supply system for a wheel loader, including an engine controller, a working pump, and a cut-off valve. The cut-off valve is connected to the liquid outlet of the working pump, and the working pump provides hydraulic oil for the working system of the loader; the cut-off valve cuts off or conducts the oil passage from the working pump to the working system of the loader according to the engine speed and the trend of engine speed change.

[0007] As an optional implementation manner, when the engine is started, during the process of the engine speed rising from zero to the engine speed n2, the cut-off valve cuts off the oil passage from the working pump to the working system of the loader; During the process of the engine speed dropping to the engine speed n2, the cut-off valve conducts the oil passage from the working pump to the working system of the loader; The engine speed n2 is any speed within 0 to 250 r / min less than the comprehensive stall speed of the engine.

[0008] As an alternative embodiment, the cut-off valve includes a check valve, a logic valve, and a solenoid valve. The check valve connects the hydraulic fluid path from the working pump to the working system of the wheel loader. The logic valve is arranged in parallel with the check valve. When the logic valve is conducting, the check valve is cut off. When the logic valve is cut off, the check valve is conducting.

[0009] As an alternative embodiment, the solenoid valve is signal-connected to the engine controller. The engine controller controls the on / off of the solenoid valve, and the solenoid valve controls the on / off of the logic valve.

[0010] As an alternative embodiment, the logic valve includes a working oil port, a load oil port, and a control oil port. The control oil port is connected to the solenoid valve. The working oil port is connected to the outlet of the working pump. The load oil port is connected to the hydraulic oil tank. The solenoid valve controls the on / off between the control oil port and the solenoid valve. When the control oil port is connected to the hydraulic oil tank through the solenoid valve, the working oil port is connected to the load oil port.

[0011] As an alternative embodiment, when the solenoid valve is energized, the control oil port is connected to the solenoid valve, and the hydraulic fluid path from the working oil port to the load oil port is connected.

[0012] As an alternative embodiment, the hydraulic fluid supply system of the wheel loader further includes a steering pump and a priority valve. The priority valve is connected to the outlet of the steering pump. The CF port of the priority valve is connected to the steering system of the wheel loader. The EF port of the priority valve is connected to the working system of the wheel loader, and on the premise that the steering pump meets the steering requirements, the excess hydraulic oil is supplied to the working system of the wheel loader through the EF port of the priority valve.

[0013] As an alternative embodiment, the hydraulic fluid supply system of the wheel loader further includes a radiator and a return oil filter. The return oil filter is arranged at the return oil port of the hydraulic oil tank. The radiator is connected to the return oil tank.

[0014] The second object of the present invention is to disclose a control method for the hydraulic fluid supply system of a wheel loader. By controlling the engine speed and the change in the engine speed of the hydraulic fluid path from the working pump to the working system of the wheel loader, it ensures precise control of the hydraulic fluid path from the working pump to the working system of the wheel loader. Within a specific speed range of the engine, it can cut off the hydraulic fluid path from the working pump to the working system of the wheel loader, and can reduce the probability of the engine stalling due to insufficient power under high load conditions (such as pressure build-up) or in a high-altitude oxygen-deficient environment.

[0015] A control method for the liquid supply system of a wheel loader, which controls the aforementioned liquid supply system of the wheel loader, includes the following processes: During the engine speed increase process, when the real-time engine speed n is less than or equal to the engine idle speed n1, the cut-off valve cuts off the oil passage from the working pump to the working system of the loader; the engine idle speed n1 is any speed value between the engine low idle speed and the engine high idle speed, and includes the engine low idle speed and the engine high idle speed; During the engine speed increase process, when the real-time engine speed n is greater than the engine idle speed n1 and less than or equal to the engine speed n2, the cut-off valve cuts off the oil passage from the working pump to the working system of the loader; the engine speed n2 is any speed value within 0 to 250 r / min less than the engine comprehensive stall speed; During the engine speed increase process, when the real-time engine speed n is greater than the engine speed n2 and less than or equal to the engine maximum speed n3, the cut-off valve conducts the oil passage from the working pump to the working system of the loader; During the engine speed decrease process, when the real-time engine speed n is less than or equal to the engine maximum speed n3 and greater than the comprehensive stall speed n2, the cut-off valve conducts the oil passage from the working pump to the working system of the loader; During the engine speed decrease process, when the real-time engine speed n is less than or equal to the engine speed n2 and greater than the engine idle speed n1, the cut-off valve conducts the oil passage from the working pump to the working system of the loader; During the engine speed decrease process, when the real-time engine speed n is less than or equal to the engine idle speed n1 and greater than zero, the cut-off valve cuts off the oil passage from the working pump to the working system of the loader.

[0016] The third object of the present invention is to disclose a wheel loader. By adding a cut-off valve in this wheel loader, and the cut-off valve controls the on / off of the oil passage from the working pump to the working system of the loader through the engine speed and the engine speed change trend, the problem that the engine is prone to flameout during high-load operation is well reduced.

[0017] To achieve the above object, the present invention discloses a wheel loader, which includes the aforementioned liquid supply system of the wheel loader, and the liquid supply system of the wheel loader is controlled according to the aforementioned control method.

[0018] Compared with the prior art, the beneficial effects of the liquid supply system of a wheel loader of the present invention are as follows: The technical solution of the present invention is to add a cut-off valve to the quantitative double-pump confluence system. Specifically, a cut-off valve is added to the oil passage from the working pump to the working system, and the cut-off valve cuts off or conducts the oil path from the working pump to the loader working system according to the engine speed and the trend of engine speed change, reducing the probability of flameout that is likely to occur at certain engine speeds.

[0019] Compared with the prior art, the beneficial effect of a control method for the liquid supply system of a wheeled loader according to the present invention lies in: by using the real-time speed of the engine to perform feedback control on the unloading pump, precise control of the on-off of the oil path from the working pump to the loader working system is achieved, reducing the load of the engine, avoiding waste of hydraulic oil, and reducing the probability of flameout that is likely to occur due to insufficient power of the engine under high-load working conditions (such as pressure holding) or in a plateau oxygen-deficient environment.

[0020] Compared with the prior art, the beneficial effect of a wheeled loader according to the present invention lies in: the aforementioned wheeled loader liquid supply system is adopted in this wheeled loader, solving the problem that the engine is extremely likely to flame out due to insufficient power under high-load working conditions (such as pressure holding) or in a plateau oxygen-deficient environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is an embodiment diagram of a liquid supply system for a wheeled loader according to the technical solution of the present invention.

[0023] Figure 2 It is an embodiment diagram of a cut-off valve in a liquid supply system for a wheeled loader according to the technical solution of the present invention.

[0024] MAIN REFERENCE NUMERAL DESCRIPTION: 1, working pump; 2, cut-off valve; 21, solenoid valve; 22, logic valve; 23, check valve; 3, hydraulic oil tank; 4, steering pump; 5, priority valve; 6, return oil filter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] In the present invention, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated device, element or component must have a specific orientation, or be constructed and operated in a specific orientation.

[0027] Moreover, in addition to being used to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0028] In addition, the terms "mounted", "arranged", "provided with", "connected", "linked" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral structure; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, or there may be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, the meaning of "a plurality" is two or more.

[0030] The technical solution of the present invention will be further described below in conjunction with embodiments and drawings.

[0031] Please refer to Figure 1 , an embodiment of the present application provides a liquid supply system for a wheel loader.

[0032] A liquid supply system for a wheel loader includes an engine controller, a working pump 1 and a cut-off valve 2. The cut-off valve 2 is connected to the liquid outlet of the working pump 1, and the working pump 1 provides hydraulic oil for the working system of the loader; the cut-off valve 2 cuts off or conducts the oil passage from the working pump 1 to the working system of the loader according to the engine speed and the trend of engine speed change.

[0033] In the fluid supply system of this wheel loader, a cut-off valve 2 is installed at the outlet of the working pump 1. The cut-off valve 2 is used to control the on-off of the oil passage from the working pump 1 to the working system of the loader. And the cut-off valve 2 cuts off or conducts the oil passage from the working pump 1 to the working system of the loader according to the engine speed and the trend of engine speed change. When the engine is in certain speed range intervals or at certain speeds, the engine will be in a full-load working state. At this time, the engine is prone to stalling. At this time, the cut-off valve 2 cuts off the oil passage from the working pump 1 to the working system of the loader, reduces the engine load, and reduces the probability of engine stalling.

[0034] In the fluid supply system of the wheel loader of this application, after the engine is started, the working pump 1 is always in the starting state, without changing the existing control logic of the engine controller. Through the logic control of the cut-off valve 2, the on-off control of the oil passage from the working pump 1 to the working system of the loader is realized, solving the problem that the engine is prone to stall when the engine matching in the existing loader is insufficient, and solving the problem that when the engine displacement of the existing loader is small or the low-speed torque is insufficient, and in high-load working conditions (such as pressure holding) or in high-altitude oxygen-deficient environments, the engine is extremely prone to stall due to insufficient power.

[0035] In the fluid supply system of the wheel loader of this application, During the process of the engine speed rising from zero to the engine speed n2, the cut-off valve cuts off the oil passage from the working pump to the working system of the loader; During the process of the engine speed dropping to the engine speed n2, the cut-off valve conducts the oil passage from the working pump to the working system of the loader; The engine speed n2 is any speed within 0 to 250 r / min less than the engine comprehensive stall speed.

[0036] The above-mentioned: during the process of the engine starting, when the engine speed rises from zero to the engine speed n2, and during the process of the engine speed dropping to the engine speed n2, both are the trends of engine speed change. That is, the trend of engine speed change is the rise or fall of the engine speed. The engine speed refers to the real-time working speed of the engine. Any speed during the process of the engine speed rising from zero to the highest working speed of the engine may be the real-time working speed of the engine.

[0037] When the engine is starting, during the process of the engine speed rising from zero to the engine speed n2, the engine goes through the engine low idle speed and the engine high idle speed. When the engine speed is between the low idle speed and the high idle speed, the engine may be in a full-load working state. At this time, the engine is prone to stalling. At this time, the cut-off valve 2 cuts off the oil passage from the working pump 1 to the working system of the loader, reduces the engine load, and reduces the probability of engine stalling.

[0038] During the process of the engine speed decreasing to the engine speed n2, the working system of the loader is still in the working state. At this time, the cut-off valve 2 conducts the oil path from the working pump 1 to the working system of the loader to ensure the normal operation of the working system of the loader.

[0039] The engine speed n2 is any speed within 0 to 250 r / min less than the engine comprehensive stall speed. That is, if the engine comprehensive stall speed is N, then (N - 250) ≤ n2 ≤ (N - 0).

[0040] In this application, the timing and state of the cut-off valve 2 in the liquid supply system of the wheel loader are as follows: 1) When the whole loader is not started, neither the working pump 1 nor the cut-off valve 2 is started, and neither the working pump 1 nor the cut-off valve 2 participates in the work.

[0041] 2) When the whole loader has just started and when the real-time engine speed n is less than or equal to the engine speed n2, the working pump 1 is started. At the same time, the cut-off valve 2 cuts off the oil path from the working pump 1 to the working system of the loader. The engine speed n2 is any speed within 0 to 250 r / min less than the engine comprehensive stall speed.

[0042] During the process of the engine speed rising, when the real-time engine speed n is in the engine speed range from the engine idle speed n1 to the engine speed n2, the cut-off valve 2 cuts off the oil path from the working pump 1 to the working system of the loader to reduce the engine load and reduce the probability of engine stalling. The engine comprehensive stall speed is a warning parameter for insufficient power of the engine under complex working conditions.

[0043] 3) After the whole loader is completely started and when the real-time engine speed n is greater than the engine speed n2, the working pump 1 is in the normal starting state, and the cut-off valve 2 conducts the oil path from the working pump 1 to the working system of the loader. 4) When the engine speed drops from the engine high speed to a certain speed, the cut-off valve 2 cuts off the oil path from the working pump 1 to the working system of the loader. Specifically, when the engine speed drops from the engine high speed to the engine idle speed n1, and when the real-time engine speed n continues to drop from the engine idle speed n1, the cut-off valve 2 cuts off the oil path from the working pump 1 to the working system of the loader. The engine high speed refers to the speed at which the engine works normally, and the engine high speed is less than or equal to the engine maximum speed, which is the speed at which the engine works normally. After the engine speed drops from the engine high speed to the engine idle speed n1, and when the real-time engine speed n continues to drop from the engine idle speed n1, the working system of the loader does not work, and the cut-off valve 2 cuts off the oil path from the working pump 1 to the working system of the loader to avoid oil waste.

[0044] In some embodiments, refer to Figure 2, the cut-off valve 2 includes a check valve 23, a logic valve 22 and a solenoid valve 21. The check valve 23 is connected to the oil circuit from the working pump 1 to the working system of the loader. The logic valve 22 is arranged in parallel with the check valve 23. When the logic valve 22 is turned on, the check valve 23 is cut off; when the logic valve 22 is cut off, the check valve 23 is turned on. The on-off of the check valve 23 controls the on-off of the oil circuit from the working pump 1 to the working system of the loader.

[0045] In this application, by adding a cut-off valve 2 to control the oil circuit from the working pump 1 to the working system of the loader, the cut-off valve 2 includes a check valve 23, a logic valve 22 and a solenoid valve 21. The valve group module has a simple structure and simple logic control. Without changing the original parameters of the whole loader, it can be added to loaders with a quantitative double-pump confluence system and can be used to transform existing loaders. It has low technical requirements, low cost and is easy to promote.

[0046] The on-off of the check valve 23 controls the on-off of the oil circuit from the working pump 1 to the working system of the loader. When the check valve 23 controls the oil circuit from the working pump 1 to the working system of the loader to close, in some working conditions, such as when the real-time engine speed is between the low idle speed and the high idle speed of the engine, the engine load is reduced, engine pressure build-up is avoided, and the probability of engine stalling is reduced.

[0047] In some embodiments, the solenoid valve 21 is signal-connected to the engine controller, and the engine controller controls the on-off of the solenoid valve 21, and the solenoid valve 21 controls the on-off of the logic valve 22.

[0048] The solenoid valve 21 is signal-connected to the engine controller, that is, the solenoid valve 21 in the cut-off valve 2 is connected to the ECU of the engine through an electrical circuit, and control logic is set in the ECU of the engine. With simple modification to the control of the engine ECU, the technical requirements are low and the cost is low. That is, based on the existing engine, the cut-off valve 2 of this application is added to mainly solve the problem of engine stalling (full load) under low oxygen content working conditions such as plateaus and tunnels.

[0049] In some embodiments, the logic valve 22 includes a working oil port (port A), a load oil port (port B) and a control oil port (port X). The working oil port is connected to and communicates with the liquid outlet of the working pump 1, and the load oil port communicates with the hydraulic oil tank 3. The solenoid valve 21 controls the on-off of the working oil port to the load oil port through the control oil port. When the control oil port is conducted with the hydraulic oil tank 3 through the solenoid valve 21, the working oil port is conducted with the load oil port.

[0050] Refer to Figure 2, in the logic valve 22, the movement of the logic valve spool is driven by the pressure difference between the control oil port and the working oil port. In the logic valve 22, the on-off of the working oil port and the load oil port is determined by the pressure of the control oil port. Specifically, the control oil port is connected to the solenoid valve 21, that is, the control oil port is connected to the hydraulic oil tank 3 through the solenoid valve 21, so that the logic valve spool in the logic valve 22 is opened, and then the working oil port is connected to the load oil port. Refer to Figure 1 and Figure 2 , in the logic valve 22, the working oil port (port A) is connected to the liquid outlet of the working pump 1, the load oil port (port B) is connected to the hydraulic oil tank 3, and the control oil port is connected to the hydraulic oil tank 3 through the solenoid valve 21.

[0051] When the control oil port is connected to the hydraulic oil tank 3 through the solenoid valve 21, the working oil port is connected to the load oil port.

[0052] When the working oil port (port A) is connected to the load oil port (port B), the hydraulic oil delivered by the working pump 1 enters the logic valve 22 through the working oil port, and then is discharged from the load oil port and the control oil port and flows back into the hydraulic oil tank 3. At this time, the hydraulic oil delivered by the working pump 1 does not enter the check valve 23, that is, it does not enter the loader working system.

[0053] When the working oil port (port A) is not connected to the load oil port (port B), the hydraulic oil delivered by the working pump 1 enters the loader working system through the check valve 23. In this way, on the one hand, it solves the problem that the fixed displacement pump always works at the rated displacement and cannot dynamically adjust the flow output according to the actual load, resulting in energy waste, and also reduces the probability that the engine is prone to flameout due to insufficient power under high load conditions (such as pressure holding) or in the plateau oxygen-deficient environment.

[0054] In some embodiments, the solenoid valve 21 is energized, the control oil port is connected to the solenoid valve 21, and the oil passage from the working oil port to the load oil port is connected.

[0055] When the solenoid valve 21 is energized, the solenoid valve 21 is connected to the control oil port of the logic valve 22, and the spool of the logic valve 22 is lifted. At this time, the working oil port of the logic valve 22 is connected to the load oil port of the logic valve 22. That is, when the oil passage between the working oil port and the control oil port of the logic valve 22 is connected, the oil passage from the working oil port to the load oil port of the logic valve 22 is also connected.

[0056] In this application, when the solenoid valve 21 is energized, the control oil port of the logic valve 22 is connected to the solenoid valve 21, the spool of the logic valve 22 is lifted, the working oil port of the logic valve 22 is connected to the control oil port, and the oil passage from the working oil port of the logic valve 22 to the load oil port is connected. When the solenoid valve 21 is de-energized, the control oil port of the logic valve 22 is disconnected from the solenoid valve 21, the spool of the logic valve 22 fails to lift, and at this time, the oil passage from the working oil port to the load oil port of the logic valve 22 is also closed. At this time, all the hydraulic oil delivered by the working pump 1 enters the check valve 23, the check valve 23 is conducted, and the hydraulic oil delivered by the working pump 1 enters the working system of the loader.

[0057] In this application, by energizing the solenoid valve 21, the conduction of the logic valve 22 is realized. In this way, if the solenoid valve 21 fails and cannot be normally energized, the oil passages from the working oil port to the load oil port and the control oil port of the logic valve 22 are in a closed state. At this time, the hydraulic oil delivered by the working pump 1 enters the working system of the loader, which will not affect the normal operation of the loader.

[0058] Refer to Figure 2 , the hydraulic oil delivered by the working pump 1 enters the valve cavity of the logic valve 22, and the T-shaped spool in the valve cavity of the logic valve 22 is subjected to the pressure of the hydraulic oil both above and below. When the solenoid valve 21 is de-energized, the solenoid valve 21 works in the left position. At this time, the upper control oil port of the logic valve 22 is not connected to the solenoid valve 21. At this time, the spool in the logic valve 22 is pressed down under the dual action of the elastic force of the spring acting on the spool and the hydraulic oil pressure, so that the working oil port of the logic valve 22 is disconnected from the load oil port. When the solenoid valve 21 is energized, the solenoid valve 21 works in the right position. At this time, the upper control oil port of the logic valve 22 is connected to the solenoid valve 21, and the hydraulic oil at the control oil port flows back to the hydraulic oil tank 3 through the solenoid valve 21, and the pressure provided by the hydraulic oil at the control oil port disappears. At this time, the spool of the logic valve 22 can be lifted, so that the passage from the working oil port to the load oil port of the logic valve 22 is conducted.

[0059] In some embodiments, the check valve 23 is signal-connected to the engine controller, and the engine controller controls the on-off of the check valve 23. The check valve 23 is controlled by the engine controller to realize dual control with the on-off control of the oil pressure control check valve 23, and the control is reliable. For the liquid supply system of the wheeled loader in this application, the main working process of the cut-off valve 2 is as follows: (1) When the whole machine of the loader has not started, the working pump 1 has not started, and the solenoid valve 21 is in a de-energized state. Refer to Figure 2 , under the action of the left spring force of the solenoid valve 21, it works in the left position, and the spool of the logic valve 22 does not open under the action of the spring force acting on the spool of the logic valve.

[0060] (2) When the whole machine of the loader has just started and when the real-time speed n of the engine is less than or equal to the engine speed n2, the working pump 1 starts, and at the same time, the solenoid valve 21 is energized. Refer toFigure 2 , the right position of the solenoid valve 21 works. At this time, the working oil port of the logic valve 22 is connected to the solenoid valve 21, and the working oil port is connected to the hydraulic oil tank 3 through the solenoid valve 21, the logic valve spool is lifted, the working oil port of the logic valve 22 is connected to the load oil port, and the load oil port is connected to the T port, that is, the load oil port is connected to the hydraulic oil tank 3, the hydraulic oil delivered by the working pump 1 flows back to the hydraulic oil tank 3 through the logic valve 22 and the solenoid valve 21, the one-way valve 23 in the cut-off valve 2 is not opened, the logic valve 22 is connected to the T port, that is, the working pump 1 is connected to T, at this time the hydraulic oil delivered by the working pump 1 is cut off and does not enter the loader working system, that is, the hydraulic oil delivered by the working pump 1 does not participate in the work.

[0061] The engine speed n2 is any speed within a range of 0 to 250 r / min less than the engine's integrated stall speed.

[0062] As the engine speed increases, if the real-time engine speed n is within the engine idle speed range of n1 to n2, shut-off valve 2 shuts off the oil line from working pump 1 to the loader's operating system, reducing the engine load and the probability of engine stall. The engine's integrated stall speed is a warning parameter for insufficient engine power under complex operating conditions.

[0063] (3) After the loader is fully started and the real-time engine speed n is greater than the engine speed n2, the working pump 1 is in the normal starting state, the solenoid valve 21 loses power, refer to Figure 2 , the solenoid valve 21 works in the left position, the valve core in the logic valve 22 fails to be lifted, the logic valve 22 is disconnected from the T port, and the one-way valve 23 in the cut-off valve 2 is opened, that is, the hydraulic oil delivered by the working pump 1 enters the loader working system and participates in the work.

[0064] (4) When the engine speed drops from the high engine speed to a certain speed, the shut-off valve 2 cuts off the oil path from the working pump 1 to the loader working system. Specifically, when the engine speed drops from the high engine speed to the engine idle speed n1, and the engine real-time speed n continues to drop from the engine idle speed n1, the solenoid valve 21 is energized, see Figure 2 , the right position of the solenoid valve 21 works. At this time, the control oil port of the logic valve 22 is connected to the solenoid valve 21, that is, the control oil port of the logic valve 22 is connected to the hydraulic oil tank 3 through the solenoid valve 21, the valve core in the logic valve 22 is lifted, the working oil port of the logic valve 22 is connected to the load oil port, and the load oil port is connected to the T port, that is, connected to the hydraulic oil tank 3, the hydraulic oil delivered by the working pump 1 flows back to the hydraulic oil tank 3 through the logic valve 22 and the solenoid valve 21, the one-way valve 23 in the cut-off valve 2 cannot be opened, the logic valve 22 is connected to the T port, that is, the working pump 1 is connected to T, at this time the hydraulic oil delivered by the working pump 1 is cut off and does not enter the loader working system, that is, the hydraulic oil delivered by the working pump 1 does not participate in the work.

[0065] In some embodiments, the liquid supply system of the wheel loader further includes a steering pump 4 and a priority valve 5. The priority valve 5 is connected to the outlet of the steering pump 4. The CF port of the priority valve 5 is connected to the steering system of the loader, and the EF port of the priority valve 5 is connected to the working system of the loader. The EF port of the priority valve 5 is provided in parallel with the outlet of the cut-off valve 2. On the premise that the steering pump meets the steering requirements, the priority valve supplies the redundant hydraulic oil to the working system of the loader through the EF port of the priority valve.

[0066] The steering pump 4 and the working pump 1 form a quantitative double-pump confluence system for the loader. When the solenoid valve 21 is de-energized, refer to Figure 2 , the solenoid valve 21 works in the left position, the logic valve 22 is disconnected from the T port, and the check valve 23 in the cut-off valve 2 is opened. That is, the hydraulic oil delivered by the working pump 1 enters the working system of the loader to participate in the work and is confluent with the flow rate of the steering pump 4 to supply the working hydraulic system.

[0067] In this application, through the combination of the steering pump 4 and the working pump 1 and the control of the hydraulic oil circuit by the cut-off valve 2, while ensuring the normal operation of the whole loader, the problem of the engine stalling and extinguishing under the low-speed section is solved. Especially when the engine displacement of the existing whole loader is smaller than that of the engines of the same tonnage in the same industry and the engine capacity cannot be improved, especially the capacity at low speeds, the problem of engine stalling is solved.

[0068] In some embodiments, the liquid supply system of the wheel loader further includes a radiator and an oil return filter 6. The oil return filter 6 is arranged at the oil return port of the hydraulic oil tank 3, and the radiator is connected to the oil return tank.

[0069] The oil return filter 6 filters the reflux hydraulic oil, filters out residues and impurities, and maintains the quality of the oil.

[0070] This application also discloses a control method for the liquid supply system of a wheel loader, which controls the aforementioned liquid supply system of the wheel loader, and the processes included are: During the process of the engine speed rising, when the real-time engine speed n is less than or equal to the engine idle speed n1, the cut-off valve 2 cuts off the oil circuit from the working pump 1 to the working system of the loader. The engine idle speed n1 is any speed value between the engine low idle speed and the engine high idle speed, and includes the engine low idle speed and the engine high idle speed.

[0071] During the process of the engine speed rising, when the real-time engine speed n is greater than the engine idle speed n1 and less than or equal to the engine speed n2, the cut-off valve 2 cuts off the oil circuit from the working pump 1 to the working system of the loader.

[0072] The engine speed n2 is any speed within 0 to 250 r / min less than the engine comprehensive stall speed.

[0073] During the engine speed rising process, when the real-time engine speed n is greater than the engine speed n2 and less than or equal to the maximum engine speed n3, the cut-off valve 2 conducts the oil circuit from the working pump 1 to the working system of the loader.

[0074] During the engine speed falling process, when the real-time engine speed n is less than or equal to the maximum engine speed n3 and greater than the comprehensive stall speed n2, the cut-off valve 2 conducts the oil circuit from the working pump 1 to the working system of the loader.

[0075] During the engine speed falling process, when the real-time engine speed n is less than or equal to the engine speed n2 and greater than the engine idle speed n1, the cut-off valve 2 conducts the oil circuit from the working pump 1 to the working system of the loader.

[0076] During the engine speed falling process, when the real-time engine speed n is less than or equal to the engine idle speed n1 and greater than zero, the cut-off valve 2 cuts off the oil circuit from the working pump 1 to the working system of the loader.

[0077] In summary, for the control method of the liquid supply system of this wheel loader, the working states of the engine, steering pump 4, working pump 1, solenoid valve 21, logic valve 22, and check valve 23 in the liquid supply system of this wheel loader are as follows: (1) The loader is shut down; the real-time engine speed n is 0; the steering pump 4 does not work; the working pump 1 does not work; the solenoid valve 21 loses power and works in the left position; the A port and B port of the logic valve 22 are not connected; the check valve 23 does not open.

[0078] (2) The loader starts; the real-time engine speed n rises, and the real-time engine speed n is greater than 0 and less than or equal to the engine idle speed n1; the steering pump 4 works, and the hydraulic oil transported supplies oil to the working system of the loader through the EF port while meeting the steering requirements; the working pump 1 works; the solenoid valve 21 is powered on and works in the right position; the spool in the logic valve 22 is lifted, the X port is connected to the solenoid valve 21, a part of the hydraulic oil at the A port of the logic valve 22 enters the hydraulic oil tank 3 through the X port, solenoid valve 21, and T port, the A port and B port of the logic valve 22 are connected, and another part of the hydraulic oil at the A port of the logic valve 22 enters the hydraulic oil tank 3 through the B port and T port; the check valve 23 does not open.

[0079] (3) The loader starts; the real-time engine speed n increases, and the real-time engine speed n is less than or equal to the engine speed n2, and greater than the engine idle speed n1; the steering pump 4 works, and the hydraulic oil delivered is supplied to the loader working system through the EF port while satisfying the steering; the working pump 1 works; the solenoid valve 21 is energized and works in the right position; the valve core in the logic valve 22 is lifted, the X port is connected to the solenoid valve 21, and a part of the hydraulic oil in the A port of the logic valve 22 enters the hydraulic oil tank 3 through the X port, the solenoid valve 21, and the T port, and the A port of the logic valve 22 is connected to the B port, and the other part of the hydraulic oil in the A port of the logic valve 22 enters the hydraulic oil tank 3 through the B port and the T port; the one-way valve 23 does not open.

[0080] (4) The loader starts; the real-time engine speed n increases, and the real-time engine speed n is less than or equal to the maximum engine speed n3, and greater than the engine speed n2; the steering pump 4 works, and the hydraulic oil delivered is supplied to the loader working system through the EF port while meeting the steering requirements; the working pump 1 works; the solenoid valve 21 loses power and works in the left position, refer to Figure 2 , the left end of the solenoid valve 21 is the left position, and the right end is the right position; the valve core in the logic valve 22 is not lifted, the X port and the solenoid valve 21 are not connected, and the A port and the B port of the logic valve 22 are not connected; the one-way valve 23 is open, and the hydraulic oil delivered by the working pump 1 passes through the one-way valve 23, mixes with the hydraulic oil from the priority valve 5EF port, and enters the loader working system.

[0081] (5) The loader starts; the real-time engine speed n decreases, and the real-time engine speed n is less than or equal to the maximum engine speed n3, and greater than the engine speed n2; the steering pump 4 works, and the hydraulic oil delivered is supplied to the loader working system through the EF port while satisfying the steering; the working pump 1 works; the solenoid valve 21 loses power and works in the left position; the valve core in the logic valve 22 is not lifted, the X port and the solenoid valve 21 are not connected, and the A port and the B port of the logic valve 22 are not connected; the one-way valve 23 is opened, and the hydraulic oil delivered by the working pump 1 passes through the one-way valve 23, mixes with the hydraulic oil from the EF port of the priority valve 5, and enters the loader working system.

[0082] (6) The loader starts; the real-time engine speed n decreases, and the real-time engine speed n is less than or equal to the engine speed n2, and greater than the engine idle speed n1; the steering pump 4 works, and the hydraulic oil delivered is supplied to the loader working system through the EF port while satisfying the steering; the working pump 1 works; the solenoid valve 21 loses power and works in the left position; the valve core in the logic valve 22 is not lifted, the X port and the solenoid valve 21 are not connected, and the A port and the B port of the logic valve 22 are not connected; the one-way valve 23 is opened, and the hydraulic oil delivered by the working pump 1 passes through the one-way valve 23, mixes with the hydraulic oil from the EF port of the priority valve 5, and enters the loader working system.

[0083] (7) The loader starts; the real-time engine speed n decreases, and the real-time engine speed n is less than or equal to the engine idle speed n1; the steering pump 4 works, and the hydraulic oil delivered is supplied to the loader working system through the EF port while satisfying the steering; the working pump 1 works; the solenoid valve 21 is energized and works in the right position; the valve core in the logic valve 22 is lifted, the X port is connected to the solenoid valve 21, and a part of the hydraulic oil in the A port of the logic valve 22 enters the hydraulic oil tank 3 through the X port, the solenoid valve 21, and the T port, and the A port of the logic valve 22 is connected to the B port, and the other part of the hydraulic oil in the A port of the logic valve 22 enters the hydraulic oil tank 3 through the B port and the T port; the one-way valve 23 does not open.

[0084] (8) The loader stops; the real-time engine speed n is 0; the steering pump 4 does not work; the working pump 1 does not work; the solenoid valve 21 loses power and works in the left position; the A port and the B port of the logic valve 22 are blocked; the one-way valve 23 does not open.

[0085] This application also discloses a wheel loader including the aforementioned wheel loader fluid supply system. This wheel loader employing the aforementioned fluid supply system reduces the probability of engine stalling due to insufficient power under high-load conditions (such as pressure buildup) or in high-altitude oxygen-deficient environments, thereby ensuring continuous operation of the loader.

[0086] The technical means disclosed in the solutions of the present invention are not limited to those disclosed in the above-mentioned embodiments, but also include technical solutions composed of any combination of the above-mentioned technical features. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A liquid supply system for a wheel loader, characterized in that, It includes an engine controller, a working pump, and a cut-off valve. The cut-off valve is connected to the liquid outlet of the working pump, and the working pump provides hydraulic oil for the loader working system. The cut-off valve cuts off or conducts the oil path from the working pump to the loader working system according to the engine speed and the trend of engine speed change.

2. The liquid supply system of the wheel loader according to claim 1, characterized in that, When the engine starts and the engine speed rises from zero to the engine speed n2, the cut-off valve cuts off the oil path from the working pump to the loader working system. When the engine speed drops to the engine speed n2, the cut-off valve conducts the oil path from the working pump to the loader working system. The engine speed n2 is any speed within 0 to 250 r / min less than the engine comprehensive stall speed.

3. The liquid supply system for a wheel loader according to claim 1 or 2, characterized in that, The cut-off valve includes a check valve, a logic valve, and a solenoid valve. The check valve connects the oil path from the working pump to the loader working system, and the logic valve is arranged in parallel with the check valve. When the logic valve is conducting, the check valve is cut off. When the logic valve is cut off, the check valve is conducting.

4. The liquid supply system of the wheel loader according to claim 3, characterized in that, The solenoid valve is signal-connected to the engine controller. The engine controller controls the on-off of the solenoid valve, and the solenoid valve controls the on-off of the logic valve.

5. The liquid supply system of the wheel loader according to claim 4, characterized in that, The logic valve includes a working oil port, a load oil port, and a control oil port. The control oil port is connected to the solenoid valve, the working oil port is connected to the liquid outlet of the working pump, and the load oil port is connected to the hydraulic oil tank. The solenoid valve controls the on-off of the control oil port and the solenoid valve. When the control oil port is conducted to the hydraulic oil tank through the solenoid valve, the working oil port is conducted to the load oil port.

6. The liquid supply system of the wheel loader according to claim 5, characterized in that, When the solenoid valve is energized, the control oil port is conducted to the solenoid valve, and the oil path from the working oil port to the load oil port is conducted.

7. The liquid supply system of the wheel loader according to claim 1, wherein It also includes a steering pump and a priority valve. The priority valve is connected to the outlet of the steering pump. The CF port of the priority valve is connected to the loader steering system, and the EF port of the priority valve is connected to the loader working system. On the premise that the steering pump meets the steering requirements, the excess hydraulic oil is supplied to the loader working system through the EF port of the priority valve.

8. The liquid supply system of the wheel loader according to claim 1, characterized in that, It also includes a radiator and a return oil filter. The return oil filter is arranged at the return oil port of the hydraulic oil tank, and the radiator is connected to the return oil tank.

9. A control method for the liquid supply system of a wheel loader, characterized in that, Controlling the liquid supply system of the wheel loader according to any one of claims 1 to 8 includes the following processes: During the process of engine speed rising, when the real-time engine speed n is less than or equal to the engine idle speed n1, the cut-off valve cuts off the oil path from the working pump to the loader working system. The engine idle speed n1 is any speed value between the engine low idle speed and the engine high idle speed, and includes the engine low idle speed and the engine high idle speed. During the process of engine speed rising, when the real-time engine speed n is greater than the engine idle speed n1 and less than or equal to the engine speed n2, the cut-off valve cuts off the oil path from the working pump to the loader working system. The engine speed n2 is any speed value within 0 to 250 r / min less than the engine comprehensive stall speed. During the process of the engine speed rising, when the real-time engine speed n is greater than the engine speed n2 and less than or equal to the maximum engine speed n3, the cut-off valve conducts the hydraulic fluid path from the working pump to the working system of the wheel loader; During the process of the engine speed falling, when the real-time engine speed n is less than or equal to the maximum engine speed n3 and greater than the engine speed n2, the cut-off valve conducts the hydraulic fluid path from the working pump to the working system of the wheel loader; During the process of the engine speed falling, when the real-time engine speed n is less than or equal to the engine speed n2 and greater than the engine idle speed n1, the cut-off valve conducts the hydraulic fluid path from the working pump to the working system of the wheel loader; During the process of the engine speed falling, when the real-time engine speed n is less than or equal to the engine idle speed n1 and greater than zero, the cut-off valve cuts off the hydraulic fluid path from the working pump to the working system of the wheel loader.

10. A wheel loader, characterized in that, Comprising the wheel loader liquid supply system according to any one of claims 1 to 8, the wheel loader liquid supply system is controlled according to the control method described in claim 9.

Images