A loader liquid supply system and a wheel loader

Abstract

The utility model discloses a kind of loader liquid supply system and wheeled loader, and loader liquid supply system includes steering liquid supply system and working liquid supply system;Steering liquid supply system and working liquid supply system are connected with cut-off valve, when the hydraulic oil pressure value in working liquid supply system is less than the preset pressure value of overflow valve in cut-off valve, the hydraulic oil output in steering liquid supply system is after priority meets steering system, and surplus part is output through check valve in cut-off valve and confluent with working liquid supply system;When the hydraulic oil pressure value in working liquid supply system reaches or greater than the preset pressure value of overflow valve in cut-off valve, cut-off valve cuts off the oil liquid passage of steering liquid supply system to working liquid supply system, and the hydraulic oil transported in steering liquid supply system is after priority meets steering system, and surplus part enters return oil circuit through logic valve in cut-off valve.The utility model's loader liquid supply system solves the problem that whole machine is extinguished under above-mentioned working condition under the premise of not changing engine power and torque.

Description

Technical Field

[0001] This utility model belongs to the field of loader fluid supply technology, specifically relating to a loader fluid supply system and a wheel loader. Background Technology

[0002] Wheel loaders, with their significant advantages such as high operating speed, high efficiency, strong mobility and convenient operation, have become the core equipment for earthwork operations in industries such as sand and gravel plants, mixing plants, highways, mines, and metallurgy. They are mainly responsible for tasks such as shoveling, transferring, loading and unloading materials and light excavation of native soil.

[0003] Currently, there are two main types of fixed-displacement hydraulic system solutions used in mainstream loaders:

[0004] One type is the fixed displacement single-pump system, in which the steering system and the working system share a large displacement fixed displacement pump. This system prioritizes the flow requirements of the steering system, with any excess flow supplied to the working hydraulic system. See the structural diagram below. Figure 1 The hydraulic oil output from the working pump first enters the priority valve, which prioritizes the operation of the steering system and delivers excess hydraulic oil to the working system.

[0005] Another type is the fixed-displacement dual-pump confluence system, which is equipped with independent steering pumps and working pumps. After prioritizing the steering system, the steering pump combines the excess flow with the output flow of the working pump through the EF port of the priority valve, and together they supply the working hydraulic system.

[0006] Whether it's a fixed-displacement single-pump system or a fixed-displacement dual-pump combined system, during operation, regardless of the engine speed, the fixed-displacement pump continuously outputs flow at its rated displacement as long as the machine is started. To meet market demands for economy, loaders of the same tonnage are typically matched with engines that have the lowest power and torque in that tonnage class. This engine and fixed-displacement pump configuration makes the engine prone to stalling under low-speed, extreme load conditions. Specifically, when using a fixed-displacement single-pump system (especially with a small-power engine), performing the following high-load extreme operations at low engine speeds can easily cause the engine to stall due to excessive instantaneous load, such as:

[0007] Steering pressure buildup: When the steering wheel is turned to its full left or right position, the steering hydraulic system experiences pressure buildup.

[0008] Bucket recovery and pressure buildup: After turning to the limit position, fully retract the bucket and allow it to build up pressure;

[0009] Lifting and holding pressure: In normal linear loading operations, after lifting the bucket to the highest position, hold pressure on the boom linkage or bucket rotation linkage.

[0010] The aforementioned engine shutdown conditions occur frequently during the daily use of economic light-duty loaders, significantly reducing customer operating experience and satisfaction, and consequently damaging the market reputation and brand image of the entire product. Utility Model Content

[0011] The purpose of this invention is to disclose a loader fluid supply system that solves the problem of engine stalling under the above-mentioned working conditions without changing the engine power and torque.

[0012] To achieve the above objectives, this utility model discloses a loader fluid supply system, including a steering fluid supply system and a working fluid supply system; a shut-off valve is connected between the steering fluid supply system and the working fluid supply system, the shut-off valve including a check valve, an overflow valve and a logic valve;

[0013] When the hydraulic oil pressure in the working fluid supply system is less than the preset pressure value of the overflow valve in the shut-off valve, the hydraulic oil output from the steering fluid supply system, after first satisfying the steering system, will have the excess portion enter the working fluid supply system through the check valve in the shut-off valve and merge with the hydraulic oil output from the working fluid supply system.

[0014] When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the shut-off valve cuts off the oil passage from the steering fluid supply system to the working fluid supply system. After the hydraulic oil output from the steering fluid supply system first satisfies the steering system, the excess portion will enter the return oil circuit connected to the logic valve in the shut-off valve through the logic valve in the shut-off valve.

[0015] As an optional implementation, the one-way valve connects the steering fluid supply system to the working fluid supply system oil circuit, and the logic valve connects the steering fluid supply system and the return oil circuit;

[0016] When the hydraulic oil pressure in the working fluid supply system is less than the preset pressure value of the relief valve in the shut-off valve, the logic valve cuts off the steering fluid supply system to the return oil circuit, and the check valve opens the steering fluid supply system to the working fluid supply system.

[0017] As an optional implementation, the overflow valve includes an external control port, an outlet port, and an inlet port. The external control port of the overflow valve is connected to the working fluid supply system, the inlet port of the overflow valve is connected to the steering fluid supply system, and the outlet port of the overflow valve is connected to the return oil circuit. When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the overflow valve in the shut-off valve, the hydraulic oil in the working fluid supply system controls the inlet port and outlet port of the overflow valve to be connected through the external control port of the overflow valve. At this time, the control port of the logic valve and the inlet port of the overflow valve are both connected to the outlet port of the overflow valve. After the hydraulic oil output from the steering fluid supply system first satisfies the steering system, the excess portion enters the return oil circuit through the logic valve.

[0018] As an optional implementation, the overflow valve includes a pressure control valve core, one side of which is connected to the working fluid supply system, and the other side of which is connected to a spring. The spring force acting on the pressure control valve core is a preset pressure value of the overflow valve in the shut-off valve, and the preset pressure value is less than the maximum pressure value of the working fluid supply system. The load size corresponding to the preset pressure value corresponds to the torque and power corresponding to the combined stall speed after the engine and torque converter of the loader are matched.

[0019] As an optional implementation, the spring force acting on the pressure control valve core is 2-3 MPa less than the maximum pressure value of the working fluid supply system.

[0020] As an optional implementation, the logic valve includes a control port, a working port, and a load port. The working port of the logic valve is connected to the steering fluid supply system, the control port of the logic valve and the inlet of the overflow valve are both connected to the steering fluid supply system, and the load port of the logic valve is connected to the return oil circuit.

[0021] When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the control port of the logic valve and the inlet port of the relief valve are both connected to the outlet port of the relief valve, and the working port of the logic valve is connected to the return oil circuit.

[0022] As an optional implementation, the steering fluid supply system includes a steering pump and a priority valve, wherein the CF port of the priority valve is connected to the steering system, and the EF port of the priority valve is connected to the shut-off valve and supplies hydraulic oil to the shut-off valve.

[0023] As an optional implementation, the working fluid supply system includes a working pump connected to the working system, and the shut-off valve is connected to the outlet of the working pump.

[0024] As an optional implementation, the displacement of the steering pump is 5cc-15cc larger than that of the working pump.

[0025] A wheel loader, including the aforementioned loader fluid supply system, solves the problem of easy engine stalling without changing the engine power and torque.

[0026] Compared with the prior art, the beneficial effects of the loader fluid supply system of this utility model are as follows:

[0027] This loader's hydraulic supply system employs a steering hydraulic supply system and a working hydraulic supply system, with a pressure-signal-controlled shut-off valve working in tandem. This achieves automatic and intelligent distribution of hydraulic flow between the steering and working systems, its core function being to dynamically optimize engine power utilization and prevent overload stalling. The system includes a return oil circuit connected to the shut-off valve, controlling its operation via a pressure threshold. This proactively unloads excess flow before the system reaches its limit load, ensuring that engine power is not excessively utilized and fundamentally eliminating the risk of stalling due to pressure buildup. Through the coordinated action of the priority valve and the shut-off valve, the system achieves convergence and acceleration under light loads, reducing work cycle time, and shuts off and unloads under heavy loads, reducing wasted energy consumption and improving fuel economy. The steering system always maintains independent hydraulic supply. Furthermore, even if the working system experiences high-pressure shut-off, steering operation remains reliable. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a simplified diagram of an existing hydraulic system.

[0030] Figure 2 This is a simplified hydraulic diagram of an embodiment of the present invention.

[0031] Figure 3 This is an enlarged view of the shut-off valve in this utility model.

[0032] Figure 4 This is a schematic diagram of the oil circuit when the hydraulic oil output from the steering fluid supply system enters the return oil circuit through the logic valve in the shut-off valve in this utility model.

[0033] Explanation of key figure labels:

[0034] 1. Steering pump; 2. Priority valve; 3. Working pump; 4. Shut-off valve; 41. Check valve; 42. Relief valve; 43. Logic valve; 5. Hydraulic oil tank. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0037] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0038] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0039] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0040] The technical solution of this utility model will be further described below with reference to the embodiments and accompanying drawings.

[0041] Please see Figure 2 and Figure 3As shown in the figure, this application provides a loader fluid supply system.

[0042] A loader fluid supply system includes a steering fluid supply system and a working fluid supply system. A shut-off valve 4 is connected between the steering fluid supply system and the working fluid supply system. The shut-off valve 4 includes a check valve 41, an overflow valve 42, and a logic valve 43.

[0043] When the hydraulic oil pressure in the working fluid supply system is less than the preset pressure value of the overflow valve in the shut-off valve, the hydraulic oil output from the steering fluid supply system, after first satisfying the steering system, will have the excess portion enter the working fluid supply system through the one-way valve 41 in the shut-off valve 4, and merge with the hydraulic oil output from the working fluid supply system.

[0044] When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the overflow valve in the shut-off valve, the shut-off valve 4 cuts off the oil passage from the steering fluid supply system to the working fluid supply system. After the hydraulic oil output from the steering fluid supply system first satisfies the steering system, the excess part will enter the return oil circuit connected to the logic valve through the logic valve in the shut-off valve.

[0045] Based on the above embodiments, a steering fluid supply system and a working fluid supply system are configured, supplying oil to the steering system and the working system respectively. The steering fluid supply system delivers hydraulic oil to the steering system to ensure its operation, while the working fluid supply system delivers hydraulic oil to the working system to ensure its operation. A shut-off valve 4 is added to connect the oil passages between the steering fluid supply system and the working fluid supply system. Specifically, the shut-off valve 4 connects the steering fluid supply system and the working fluid supply system, controlling whether the excess hydraulic oil output from the steering fluid supply system enters the working fluid supply system after first satisfying the steering system's needs.

[0046] In the above embodiment, the hydraulic oil pressure value in the working fluid supply system is less than the preset pressure value of the relief valve in the shut-off valve, indicating that the hydraulic oil in the working system has not yet reached the required maximum flow rate. In order to ensure the operation of the working system, the working system needs more hydraulic oil. Therefore, at this time, the hydraulic oil output from the steering fluid supply system will first satisfy the steering system, and the excess part will be output to the working system to merge with the hydraulic oil output from the working fluid supply system.

[0047] In the above embodiments, when the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, it indicates that the flow rate of hydraulic oil in the working system has reached the maximum value required for hydraulic oil, and there is no longer a need for the hydraulic oil output from the steering fluid supply system to supplement it. Therefore, at this time, the shut-off valve 4 cuts off the oil passage from the steering fluid supply system to the working fluid supply system. Thus, after the hydraulic oil output from the steering fluid supply system prioritizes the steering system, the excess portion is no longer output to the working fluid supply system.

[0048] In this embodiment, a steering fluid supply system and a working fluid supply system are used in conjunction with a shut-off valve 4. The shut-off valve 4 controls the oil passage from the steering fluid supply system to the working fluid supply system, controlling whether the excess hydraulic oil output from the steering fluid supply system merges with the hydraulic oil output from the working fluid supply system after satisfying the steering system's operation, and whether it participates in the working system's operation, thus solving the problem of engine stalling. Specifically, the original large-displacement fixed-displacement pump fluid supply system is optimized into a steering fluid supply system and a working fluid supply system, solving the problem of engine stalling under full load operation caused by the low power and torque of the engine in the loader and the fixed-displacement pump always being at full load.

[0049] This loader's hydraulic supply system employs a steering hydraulic supply system and a working hydraulic supply system, with a pressure-signal-controlled shut-off valve 4 working in tandem. This achieves automatic and intelligent distribution of hydraulic flow between the steering and working systems, its core function being to dynamically optimize engine power utilization and prevent overload stalling. The system includes a return oil circuit connected to a logic valve in shut-off valve 4. Pressure threshold control of shut-off valve 4 activates it, actively unloading excess flow before the system reaches its limit load, ensuring engine power is not excessively utilized and fundamentally eliminating the risk of stalling due to pressure buildup. In this system, the priority valve 2 and shut-off valve 4 work together to merge and accelerate under light loads, reducing work cycle time, and to cut off and unload under heavy loads, reducing wasted energy consumption and improving fuel economy. The steering system always maintains independent hydraulic supply. Furthermore, even if the working system experiences high-pressure shut-off, steering operation remains reliable.

[0050] In this embodiment, the control strategy of the loader's fluid supply system is to use the pressure value of the working fluid supply system to control the opening and closing of the shut-off valve. By controlling the opening and closing of the shut-off valve 4, the oil passage from the steering fluid supply system to the working fluid supply system is opened and closed, thereby controlling the maximum pressure of the working fluid supply system. This limits the maximum load of the entire machine, which makes up for the problem that the engine power and torque values ​​do not meet the requirements of the load exceeding the engine capacity under extreme working conditions. This ensures that the entire machine can work normally without stalling, completely solves the problem of engine stalling, improves product competitiveness, and solves the problem of easy engine stalling in existing machines.

[0051] In this embodiment, the load size corresponding to the preset pressure value corresponds to the torque and power corresponding to the combined stall speed after the engine and torque converter of the loader are matched. The on / off state of the cut-off valve 4 is controlled by the preset pressure value of the relief valve in the cut-off valve, which controls the destination of excess hydraulic oil in the steering fluid supply system, limits the maximum load of the whole machine, and makes the maximum load of the whole machine match the maximum output torque and corresponding power of the engine, so as to avoid the engine stalling problem caused by the engine output torque being less than the torque required by the whole machine at maximum load.

[0052] In this application, the preset pressure value of the relief valve in the shut-off valve is matched with the maximum output torque and corresponding power of the loader engine. That is, the load size corresponding to the preset pressure value corresponds to the torque and power corresponding to the combined stall speed after the engine and torque converter of the loader are matched. By controlling the on / off state of the shut-off valve 4 through this preset pressure value, the destination of excess hydraulic oil in the steering fluid supply system can be dynamically adjusted. When the system pressure is lower than the preset value, the excess oil merges with the working fluid supply system, and the working fluid supply system increases the flow rate; when the system pressure reaches or exceeds the preset value, the shut-off valve 4 closes the merging path, and the excess oil is unloaded and enters the return oil tank. The control mechanism of this application limits the maximum load peak of the whole machine hydraulic system, so that it always matches the maximum output torque and corresponding power of the engine, thereby completely avoiding the stalling problem caused by the load torque demand exceeding the engine's bearing limit.

[0053] In some embodiments, see Figure 2 In the middle, the oil circuit between the shut-off valve 4 and the hydraulic oil tank 5 is the return oil circuit, and the hydraulic oil tank 5 is also used as a return oil tank.

[0054] In some embodiments, see Figure 2 and Figure 3 The shut-off valve 4 includes a check valve 41 and a relief valve 42. The check valve 41 connects the steering fluid supply system to the working fluid supply system oil circuit, and the logic valve 43 connects the steering fluid supply system and the return oil circuit.

[0055] When the hydraulic oil pressure in the working fluid supply system is less than the preset pressure value of the relief valve in the shut-off valve, the relief valve 42 cuts off the oil circuit from the steering fluid supply system to the return oil circuit, and the check valve 41 opens the oil circuit from the steering fluid supply system to the working fluid supply system.

[0056] like Figure 2 When the hydraulic oil pressure in the working fluid supply system is lower than the preset pressure of the relief valve in the shut-off valve, the relief valve 42 cuts off the steering fluid supply system from the return oil circuit. At this time, the hydraulic oil output from the steering fluid supply system, after first meeting the working needs of the steering system, has the excess portion entering the shut-off valve 4. The hydraulic oil's own pressure opens the check valve 41 in the shut-off valve 4, allowing the excess hydraulic oil output from the steering fluid supply system to flow back to the working fluid supply system through the check valve 41. This ensures the hydraulic pressure required by the working system and prevents the engine from stalling due to insufficient output capacity.

[0057] In some embodiments, see Figure 3 and Figure 4The relief valve 42 includes an external control port (A2 port), an outlet port (B2 port), and an inlet port (P2 port). The external control port (A2 port) of the relief valve 42 is connected to the working fluid supply system, the inlet port (P2 port) of the relief valve 42 is connected to the steering fluid supply system, and the outlet port (B2 port) of the relief valve 42 is connected to the return oil circuit. When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the hydraulic oil in the working fluid supply system controls the inlet port and outlet port of the relief valve 42 to be connected through the external control port of the relief valve 42. At this time, the control port in the logic valve and the inlet port of the relief valve are both connected to the outlet port of the relief valve. After the hydraulic oil output from the steering fluid supply system first satisfies the steering system, the excess portion enters the return oil circuit through the logic valve 43.

[0058] See Figure 3 The external control port (A2 port) of the relief valve 42 is connected to the working fluid supply system. The opening and closing of the relief valve 42 is controlled by the hydraulic oil pressure in the working fluid supply system and the external control port (A2 port) of the relief valve 42. When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the oil circuit from the oil inlet (P2 port) to the oil outlet (B2 port) of the relief valve 42 is connected. The hydraulic oil output from the steering fluid supply system, after first satisfying the steering system, the excess part enters the return oil circuit through the logic valve 43 to achieve oil return, limiting the maximum load peak of the entire hydraulic system, so that it always matches the maximum output torque and corresponding power of the engine, thereby completely avoiding the stalling problem caused by the load torque demand exceeding the engine's bearing limit.

[0059] In some embodiments, see Figure 2 and Figure 3 The overflow valve 42 includes a pressure control valve core. One side of the pressure control valve core is connected to the working fluid supply system, and the other side of the pressure control valve core is connected to a spring. The spring force acting on the pressure control valve core is the preset pressure value of the overflow valve, which is less than the maximum pressure value of the working fluid supply system. The load size corresponding to the preset pressure value corresponds to the torque and power corresponding to the combined stall speed after the engine and torque converter of the loader are matched.

[0060] In this embodiment, the pressure control valve core of the overflow valve 42 is controlled by a spring and the pressure of the working fluid supply system. When the pressure exerted by the working fluid supply system on the pressure control valve core of the overflow valve 42 is greater than the spring force exerted by the spring on the pressure control valve core of the overflow valve 42, the pressure control valve core of the overflow valve 42 is opened, i.e., as... Figure 3In this process, the pressure control valve core of the relief valve 42 moves downward, opening the oil passage from the inlet (P2 port) to the outlet (B2 port) of the relief valve 42. At this time, the logic valve 43 opens the return oil passage due to the open oil passage between the inlet (P2 port) and outlet (B2 port) of the relief valve 42, thus opening the passage between the EF port of the priority valve 2 and the return oil passage. At this point, the hydraulic oil output from the steering fluid supply system, after prioritizing the steering system, will have excess oil enter the return oil passage through the logic valve 43. In other words, the relief valve 42 closes the combined flow path to the working fluid supply system, and the excess oil is unloaded and enters the return oil tank. This achieves the goal of limiting the maximum load peak of the entire hydraulic system, ensuring that the maximum load peak of the entire hydraulic system always matches the engine's maximum output torque and corresponding power, avoiding engine stalling caused by the load torque demand exceeding the engine's bearing limit.

[0061] In some embodiments, the spring force acting on the pressure control valve core is 2-3 MPa less than the maximum pressure of the working fluid supply system. The spring force acting on the pressure control valve core is a preset pressure value, which matches the maximum torque of the engine to ensure that the hydraulic system does not stall when under full load.

[0062] In some embodiments, see Figure 3 and Figure 4 The shut-off valve 4 also includes a logic valve 43, which includes a control port (B1), a working port (P1), and a load port (A1). The working port (P1) of the logic valve 43 is connected to the steering fluid supply system. The control port (B1) of the logic valve 43 and the inlet port (P2) of the relief valve 42 are both connected to the steering fluid supply system. The load port (A1) of the logic valve 43 is connected to the return oil circuit. When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the control port of the logic valve 43 and the inlet port (P2) of the relief valve are both connected to the outlet port (B2) of the relief valve 42. The working port (P1) of the logic valve 43 is connected to the return oil circuit through the load port (A1) of the logic valve 43.

[0063] See Figure 4 When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the hydraulic oil pressure in the working fluid supply system acts on the external control port (A2 port) of the relief valve 42. The pressure control valve core of the relief valve 42 moves downward, and the oil inlet (P2 port) to the oil outlet (B2 port) of the relief valve 42 is connected. At this time, the control port (B1 port) of the logic valve 43 is connected to the return oil circuit through the relief valve 42. Figure 4As shown, the pressure on the left side of the spring chamber of logic valve 43 is zero, and the right side of the spring chamber is connected to the EF port of priority valve 2. The pressure on the right side of the spring chamber is greater than the pressure on the left side of the spring chamber of logic valve 43. The spring chamber of logic valve 43 moves to the left, and the working oil port (P1 port) of logic valve 43 is connected to the load oil port (A1 port) of logic valve 43.

[0064] At this time, the hydraulic oil output from the EF port of priority valve 2 is input through the working port (P1 port) of logic valve 43, then flows into the return oil circuit through the load port (A1 port) of logic valve 43, and enters the hydraulic oil tank 5. (See reference...) Figure 4 The oil passage is indicated by the dashed line.

[0065] See Figure 4 When the hydraulic oil pressure in the working fluid supply system is less than the preset pressure of the relief valve in the shut-off valve, the hydraulic oil pressure in the working fluid supply system acting on the external control port (A2 port) of the relief valve 42 decreases, the pressure control valve core of the relief valve 42 moves upward, and the oil inlet (P2 port) to the oil outlet (B2 port) of the relief valve 42 closes. At this time, the pressure on the right side of the spring chamber in the logic valve 43 is zero, and the pressure on the left side of the spring chamber in the logic valve 43 is greater than the pressure on the right side. The spring chamber in the logic valve 43 moves to the right, and the oil circuit from the working oil port (P1 port) of the logic valve 43 to the control oil port (B1 port) and the load oil port (A1 port) of the logic valve 43 is cut off. At this time, the hydraulic oil output from the EF port of the priority valve 2 can no longer enter the return oil circuit through the logic valve 43. Therefore, the hydraulic oil output from the EF port of the priority valve 2 will enter the working fluid supply system again through the check valve 41 and merge with the working fluid supply system to ensure the normal operation of the whole machine.

[0066] In this application, the logic valve 43 and the relief valve 42 are combined to realize automatic control of the opening and closing of the shut-off valve 4 by the pressure of the hydraulic oil in the system. The control is simple and convenient, and the control is precise.

[0067] In some embodiments, see Figure 2 The steering fluid supply system includes a steering pump 1 and a priority valve 2. The CF port of the priority valve 2 is connected to the steering system, and the EF port of the priority valve 2 is connected to the shut-off valve 4 and supplies hydraulic oil to the shut-off valve 4. The priority valve 2 distributes the hydraulic pressure in the steering fluid supply system, first ensuring the working needs of the steering system, and then supplying excess hydraulic oil to the working fluid supply system side.

[0068] In some embodiments, the working fluid supply system includes a working pump 3, which is connected to the working system, and a shut-off valve 4 is connected to the outlet of the working pump 3. In this application, the sum of the displacement of the steering pump 1 and the displacement of the working pump 3 is greater than or equal to the displacement of the large-displacement single pump before optimization, thus ensuring the normal operation of the working system and the steering system, especially ensuring the normal operation of the working system.

[0069] In this system, the pressure value of the working hydraulic system is used to control the on / off connection of the steering pump 1 to the working hydraulic system through the shut-off valve 4, thereby controlling the maximum pressure of the working hydraulic system and limiting the maximum load of the whole machine. This completely solves the problem of engine stalling when the whole machine is working at full load in various speed ranges due to the insufficient capacity of the existing engine.

[0070] In some embodiments, the displacement of the steering pump 1 is 5cc-15cc larger than that of the working pump 3 to ensure the normal operation of the working system and the steering system, especially the normal operation of the working system.

[0071] A wheel loader includes the aforementioned loader fluid supply system. This solves the problem of easy engine stalling in the wheel loader without changing the engine power and displacement.

[0072] The technical means disclosed in this utility model are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications are also considered within the scope of protection of this utility model.

Claims

1. A loader fluid supply system characterized by, It includes a steering fluid supply system and a working fluid supply system; a shut-off valve is connected between the steering fluid supply system and the working fluid supply system, and the shut-off valve includes a check valve, an overflow valve and a logic valve; When the hydraulic oil pressure in the working fluid supply system is less than the preset pressure value of the overflow valve in the shut-off valve, the hydraulic oil output from the steering fluid supply system, after first satisfying the steering system, will have the excess portion enter the working fluid supply system through the check valve in the shut-off valve and merge with the hydraulic oil output from the working fluid supply system. When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the shut-off valve cuts off the oil passage from the steering fluid supply system to the working fluid supply system. After the hydraulic oil output from the steering fluid supply system first satisfies the steering system, the excess portion will enter the return oil circuit connected to the logic valve in the shut-off valve through the logic valve in the shut-off valve.

2. The loader fluid supply system according to claim 1, characterized in that, The one-way valve connects the steering fluid supply system to the working fluid supply system oil circuit, and the logic valve connects the steering fluid supply system and the return oil circuit; When the hydraulic oil pressure in the working fluid supply system is less than the preset pressure value of the relief valve in the shut-off valve, the logic valve cuts off the steering fluid supply system to the return oil circuit, and the check valve opens the steering fluid supply system to the working fluid supply system.

3. The loader fluid supply system according to claim 2, characterized in that, The overflow valve includes an external control port, an outlet port, and an inlet port. The external control port of the overflow valve is connected to the working fluid supply system, the inlet port of the overflow valve is connected to the steering fluid supply system, and the outlet port of the overflow valve is connected to the return oil circuit. When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the overflow valve in the shut-off valve, the hydraulic oil in the working fluid supply system controls the inlet port and outlet port of the overflow valve to be connected through the external control port of the overflow valve. At this time, the control port of the logic valve and the inlet port of the overflow valve are both connected to the outlet port of the overflow valve. After the hydraulic oil output from the steering fluid supply system first satisfies the steering system, the excess hydraulic oil enters the return oil circuit through the logic valve.

4. The loader fluid supply system according to claim 3, characterized in that, The overflow valve includes a pressure control valve core, one side of which is connected to the working fluid supply system, and the other side of which is connected to a spring. The spring force acting on the pressure control valve core is the preset pressure value of the overflow valve in the shut-off valve. The preset pressure value is less than the maximum pressure value of the working fluid supply system. The load size corresponding to the preset pressure value corresponds to the torque and power corresponding to the combined stall speed after the engine and torque converter of the loader are matched.

5. The loader fluid supply system according to claim 4, characterized in that, The spring force acting on the pressure control valve core is 2-3 MPa less than the maximum pressure value of the working liquid supply system.

6. The loader fluid supply system according to claim 3, characterized in that, The logic valve includes a control port, a working port, and a load port. The working port of the logic valve is connected to the steering fluid supply system. The control port of the logic valve and the inlet of the overflow valve are both connected to the steering fluid supply system. The load port of the logic valve is connected to the return oil circuit. When the hydraulic oil pressure in the working fluid supply system reaches or exceeds the preset pressure value of the relief valve in the shut-off valve, the control port of the logic valve and the inlet port of the relief valve are both connected to the outlet port of the relief valve, and the working port of the logic valve is connected to the return oil circuit.

7. The loader fluid supply system according to claim 1, characterized in that, The steering fluid supply system includes a steering pump and a priority valve. The CF port of the priority valve is connected to the steering system, and the EF port of the priority valve is connected to the shut-off valve and supplies hydraulic oil to the shut-off valve.

8. The loader fluid supply system according to claim 7, characterized in that, The working liquid supply system includes a working pump, which is connected to the working system, and the shut-off valve is connected to the outlet of the working pump.

9. The loader fluid supply system according to claim 8, characterized in that, The displacement of the steering pump is 5cc-15cc larger than that of the working pump.

10. A wheel loader, characterized in that, Includes the loader fluid supply system as described in any one of claims 1 to 9.

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