Hydraulic control system and skid steer loader

Abstract

The utility model belongs to hydraulic control technical field, concretely relates to a kind of hydraulic control system and skid loader, and hydraulic control system includes: oil supply oil circuit, including first working oil circuit and second working oil circuit;Boom cylinder, the rod cavity of boom cylinder is communicated with first working oil circuit;Shovel cylinder, the rodless cavity of shovel cylinder is communicated with second working oil circuit;Leveling valve group, the first oil port of leveling valve group is communicated with first working oil circuit, the second oil port of leveling valve group is communicated with second working oil circuit, the third oil port of leveling valve group is communicated with hydraulic oil tank, in the case where boom cylinder's rod cavity oil outlet, leveling valve group is used to shunt the hydraulic oil of first working oil circuit to second working oil circuit and hydraulic oil tank;Leveling switch valve, the oil outlet end of leveling switch valve is communicated with hydraulic oil tank, and leveling switch valve is used to carry out pressure relief to first working oil circuit.The hydraulic control system described above can make skid loader meet the operation demand under different conditions.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic control technology, specifically relating to a hydraulic control system and a skid steer loader. Background Technology

[0002] Skid steer loaders are multi-functional work machines widely used in various narrow or complex working environments. They are compact in structure, flexible in operation, and can accomplish a variety of tasks by changing different attachments.

[0003] In existing technology, when a skid steer loader with automatic leveling is in operation, the hydraulic oil in the rod chamber of the boom cylinder returns to the leveling valve when the boom moves upward. The leveling valve distributes the flow, with some hydraulic oil flowing back to the hydraulic tank and the rest flowing to the rodless chamber of the bucket cylinder, allowing the bucket to move upward with the boom, thus achieving automatic leveling of the boom and bucket. However, in some operating conditions of skid steer loaders, the bucket does not need to move upward during the boom's upward movement. Because of the presence of the leveling valve in existing technology, the independent upward movement of the boom cannot be achieved, thus limiting the operating conditions of the skid steer loader. Utility Model Content

[0004] The purpose of this invention is to provide a hydraulic control system and a skid steer loader to solve the technical problem that the boom of a skid steer loader with automatic leveling function cannot move upward independently in the prior art.

[0005] To achieve the above objectives, this utility model provides a hydraulic control system, which includes:

[0006] The oil supply circuit includes a first working oil circuit and a second working oil circuit;

[0007] The boom cylinder has its rod chamber connected to the first working oil circuit;

[0008] The bucket cylinder has a rodless chamber that is connected to the second working oil circuit.

[0009] The leveling valve assembly has a first oil port connected to the first working oil circuit, a second oil port connected to the second working oil circuit, and a third oil port connected to the hydraulic oil tank. When oil is discharged from the rod chamber of the boom cylinder, the leveling valve assembly is used to divert the hydraulic oil from the first working oil circuit to the second working oil circuit and the hydraulic oil tank.

[0010] The leveling switch valve has its outlet end connected to the hydraulic oil tank and is used to depressurize the first working oil circuit.

[0011] In some implementations, the oil inlet of the leveling switch valve is connected to the working oil circuit between the rod chamber and the first oil port of the boom cylinder.

[0012] In some implementations, the oil inlet of the leveling switch valve is connected to the second working oil circuit.

[0013] In some embodiments, the leveling valve assembly includes: a flow divider valve having a flow divider valve inlet, a first outlet, and a second outlet, wherein the flow divider valve inlet is connected to a first working oil circuit, the first outlet is connected to a hydraulic oil tank, and the second outlet is connected to a second working oil circuit.

[0014] In some embodiments, a first connecting oil passage is connected between the second oil outlet and the second working oil passage, and the oil inlet of the leveling switch valve is connected to the first connecting oil passage.

[0015] In some implementations, the leveling switch valve is a normally closed two-position two-way solenoid valve.

[0016] The second aspect of this utility model provides a hydraulic control system, comprising: an oil supply circuit, including a first working oil circuit and a second working oil circuit; a boom cylinder, the rod-side chamber of which is connected to the first working oil circuit; a bucket cylinder, the rodless side chamber of which is connected to the second working oil circuit; and a leveling valve assembly, the first port of which is connected to the first working oil circuit, the second port of which is connected to the second working oil circuit, and the third port of which is connected to a hydraulic oil tank. The leveling valve assembly is used to divert hydraulic oil from the first working oil circuit to the second working oil circuit and the hydraulic oil tank. The leveling valve assembly includes a leveling switch valve, which is used to open or close the oil circuit between the first port and the second port.

[0017] In some embodiments, the leveling valve assembly further includes: a flow divider valve having a flow divider valve inlet, a first outlet, and a second outlet; the flow divider valve inlet is connected to a first working oil circuit; the first outlet is connected to a hydraulic oil tank; the second outlet is connected to a second working oil circuit; and a leveling switch valve is connected to a second connecting oil circuit between the second outlet and the second working oil circuit.

[0018] In some implementations, the leveling switch valve is a normally open two-position two-way solenoid valve.

[0019] A third aspect of this invention provides a skid steer loader, including the aforementioned hydraulic control system.

[0020] The above technical solution provides a hydraulic control system, which includes an oil supply circuit, a boom cylinder, a bucket cylinder, a leveling valve assembly, and a leveling switch valve. The oil supply circuit includes a first working circuit and a second working circuit. The rod-side chamber of the boom cylinder is connected to the first working circuit, and the rodless chamber of the bucket cylinder is connected to the second working circuit. The first port of the leveling valve assembly is connected to the first working circuit, the second port is connected to the second working circuit, and the third port is connected to the hydraulic oil tank. When oil is discharged from the rod-side chamber of the boom cylinder, the leveling valve assembly can divert hydraulic oil from the first working circuit to the second working circuit and the hydraulic oil tank, so that the bucket cylinder extends along with the boom cylinder. The outlet of the leveling switch valve is connected to the hydraulic oil tank. The leveling switch valve can depressurize the first working circuit to control the flow direction of the hydraulic oil flowing out of the first working circuit, thereby controlling whether the bucket cylinder extends along with the boom cylinder. Using the aforementioned hydraulic control system, when the boom needs to move upwards independently, the pressure relief in the first working oil circuit can be adjusted by controlling the opening or closing of the leveling switch valve. When the leveling switch valve is open, the hydraulic oil in the first working oil circuit can flow back to the hydraulic oil tank through the valve. At this time, the bucket cylinder will not extend along with the boom cylinder, achieving independent upward movement of the boom. When the leveling switch valve is closed, the hydraulic oil in the first working oil circuit cannot flow back to the hydraulic oil tank, but instead is diverted to the second working oil circuit, causing the bucket cylinder to extend along with the boom cylinder, achieving automatic leveling of the boom and bucket. This design not only improves the flexibility of the skid steer loader but also meets the operational needs under different working conditions, possessing high practical value.

[0021] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without any inventive effort. In the drawings:

[0023] Figure 1 The hydraulic schematic diagram is provided for the hydraulic control system according to the first embodiment of this utility model.

[0024] Figure 2 The hydraulic schematic diagram is provided for the hydraulic control system according to the second embodiment of this utility model.

[0025] Figure 3The hydraulic schematic diagram is provided for the hydraulic control system according to the third embodiment of this utility model.

[0026] Figure 4 This is a hydraulic schematic diagram of a hydraulic control system provided according to the fourth embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] 10 Boom cylinders

[0029] 20 Bucket Hydraulic Cylinder

[0030] 30 leveling valve assembly

[0031] 31 Diverter Valve

[0032] 32 Hydraulic control switch valve

[0033] 33. Overflow valve

[0034] 34 Check valve

[0035] 40 Leveling switch valve

[0036] 50-way valve

[0037] L1 First Working Oil Circuit

[0038] L2 Second Working Oil Circuit

[0039] L3 Third Working Oil Circuit

[0040] L4 Fourth Working Oil Circuit

[0041] L5 First Connecting Oil Circuit

[0042] L6 Second Connecting Oil Circuit

[0043] L7 Third Connecting Oil Circuit Detailed Implementation

[0044] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0045] The hydraulic control system and skid steer loader according to this utility model are described below with reference to the accompanying drawings. Figure 1 The diagram shown is a hydraulic schematic of a hydraulic control system according to the first embodiment of the present invention. The hydraulic control system includes:

[0046] The oil supply circuit includes the first working oil circuit L1 and the second working oil circuit L2;

[0047] The boom cylinder 10 has its rod chamber connected to the first working oil circuit L1.

[0048] Bucket cylinder 20, the rodless chamber of bucket cylinder 20 is connected to the second working oil circuit L2;

[0049] The leveling valve assembly 30 has a first oil port connected to the first working oil circuit L1, a second oil port connected to the second working oil circuit L2, and a third oil port connected to the hydraulic oil tank (not shown in the figure). When oil is discharged from the rod chamber of the boom cylinder 10, the leveling valve assembly 30 is used to divert the hydraulic oil of the first working oil circuit L1 to the second working oil circuit L2 and the hydraulic oil tank.

[0050] The leveling switch valve 40 has its oil outlet connected to the hydraulic oil tank. The leveling switch valve 40 is used to depressurize the first working oil circuit L1.

[0051] In the prior art, the bucket and boom of a skid steer loader are driven by a bucket cylinder 20 and a boom cylinder 10, respectively. However, the hydraulic leveling switching function of the boom and bucket has certain limitations. In particular, under certain specific working conditions, it is necessary for the boom to be able to move upward independently without moving the bucket together, and the existing skid steer loaders with built-in leveling valves cannot meet this requirement.

[0052] To address the aforementioned problems, this utility model proposes a hydraulic control system, which includes an oil supply circuit, a boom cylinder 10, a bucket cylinder 20, a leveling valve assembly 30, and a leveling switch valve 40. The oil supply circuit includes a first working circuit L1 and a second working circuit L2. The rod-side chamber of the boom cylinder 10 is connected to the first working circuit L1, and the rodless chamber of the bucket cylinder 20 is connected to the second working circuit L2. The first and second working circuits L1 and L2 can respectively supply oil to the rod-side chamber of the boom cylinder 10 and the rodless chamber of the bucket cylinder 20. The leveling valve assembly 30 has a first port, a second port, and a third port. The first port is connected to the first working circuit L1, the second port is connected to the second working circuit L2, and the third port is connected to the hydraulic oil tank. The leveling valve assembly 30 can divert hydraulic oil from the first working oil circuit L1 to the second working oil circuit L2 and the hydraulic oil tank when oil is discharged from the rod chamber of the boom cylinder 10, thereby achieving coordinated movement of the bucket and the boom. The outlet of the leveling switch valve 40 is connected to the hydraulic oil tank. The leveling switch valve 40 is used to depressurize the first working oil circuit L1. When the boom needs to move upward independently, the pressure in the first working oil circuit L1 can be depressurized by controlling the opening of the leveling switch valve 40, so that the hydraulic oil in the first working oil circuit L1 can flow back to the hydraulic oil tank through the leveling switch valve 40. At this time, the bucket cylinder 20 will not receive hydraulic oil from the first working oil circuit L1, and therefore will not extend with the boom cylinder 10, thereby achieving independent upward movement of the boom. When coordinated movement of the boom and bucket is required, i.e., to achieve automatic leveling, the hydraulic oil in the first working circuit L1 can be prevented from flowing directly back to the hydraulic oil tank by controlling the closing of the leveling switch valve 40. This allows the hydraulic oil in the first working circuit L1 to be diverted to the second working circuit L2 through the leveling valve, driving the bucket cylinder 20 to extend along with the boom cylinder 10. This design not only improves the operational flexibility of the skid steer loader but also enables it to adapt to more diverse operating conditions, greatly enhancing its practical value.

[0053] In one embodiment, such as Figure 1 As shown, the third oil port of the leveling valve group 30 is also connected to the hydraulic oil tank via a multi-way valve 50. The oil supply circuit also includes a third working oil circuit L3, which is connected to the rodless chamber of the boom cylinder 10. The multi-way valve 50 can control the flow direction of hydraulic oil in the first working oil circuit L1 and the second working oil circuit L2.

[0054] In the first embodiment, such as Figure 1As shown, the oil inlet of the leveling switch valve 40 is connected to the working oil circuit between the rod chamber and the first oil port of the boom cylinder 10. Thus, when oil exits from the rod chamber of the boom cylinder 10, the hydraulic oil can flow back to the hydraulic oil tank through the leveling switch valve 40, thereby relieving pressure on the first working oil circuit L1. The opening and closing states of the leveling switch valve 40 can be controlled by the electronic control system, thereby achieving precise control of the movement of the skid steer loader's boom and bucket.

[0055] In the second embodiment, as Figure 2 The diagram shows the hydraulic principle of the hydraulic control system according to the second embodiment of this utility model. The oil inlet of the leveling switch valve 40 is connected to the second working oil circuit L2. Thus, the leveling switch valve 40 can control the flow direction of the hydraulic oil in the second working oil circuit L2 to depressurize the first working oil circuit L1. When the leveling switch valve 40 is open, the hydraulic oil in the second working oil circuit L2 can flow back to the hydraulic oil tank after passing through the leveling switch valve 40. At this time, the hydraulic oil in the first working oil circuit L1 will flow to the hydraulic oil tank in two separate paths, thereby depressurizing the first working oil circuit L1. This design provides another way to achieve independent upward movement of the boom, further improving the operational flexibility of the skid steer loader.

[0056] In one embodiment, such as Figure 1 As shown, the leveling valve assembly 30 includes a flow divider valve 31. The flow divider valve 31 has a flow divider valve inlet, a first outlet, and a second outlet. The flow divider valve inlet is connected to the first working oil circuit L1, the first outlet is connected to the hydraulic oil tank, and the second outlet is connected to the second working oil circuit L2. The flow divider valve 31 is a valve that can distribute the incoming hydraulic oil to different outlets in a certain proportion. In this utility model, the flow divider valve 31 has its inlet connected to the first working oil circuit L1, its first outlet connected to the hydraulic oil tank, and its second outlet connected to the second working oil circuit L2. Thus, when oil is discharged from the rod chamber of the boom cylinder 10 and the leveling switch valve 40 is in the closed state, the hydraulic oil in the first working oil circuit L1 can flow through the flow divider valve 31, with part flowing to the hydraulic oil tank and the other part flowing to the second working oil circuit L2, thereby driving the bucket cylinder 20 to extend and realizing the coordinated movement of the boom and the bucket.

[0057] In addition, the oil supply circuit also includes a fourth working oil circuit L4, which is connected to the rod chamber of the bucket cylinder 20. The leveling valve assembly 30 also includes a hydraulic control valve 32 and a relief valve 33. The inlet of the hydraulic control valve 32 is connected to the fourth working oil circuit L4, and the outlet of the hydraulic control valve 32 is connected to the hydraulic oil tank. A first connecting oil circuit L5 is connected between the second outlet of the diverter valve 31 and the second working oil circuit L2. The control port of the hydraulic control valve 32 is connected to the first connecting oil circuit L5. When the pressure in the first connecting oil circuit L5 rises, the hydraulic control valve 32 can be opened. With the above structure, the hydraulic oil flowing out of the second outlet of the diverter valve 31 enters the rodless chamber of the bucket cylinder 20, and the hydraulic oil in the rod chamber of the bucket cylinder 20 flows sequentially through the fourth working oil circuit L4 and the hydraulic control valve 32 to the hydraulic oil tank. The inlet of the relief valve 33 is connected to the first connecting oil circuit L5, and the outlet of the relief valve 33 is connected to the hydraulic oil tank. When the pressure of the first connecting oil circuit L5 is too high, the relief valve 33 can release the hydraulic oil in the first connecting oil circuit L5 to prevent the high-pressure hydraulic oil from damaging the pipeline and hydraulic components.

[0058] In one embodiment, the leveling valve assembly 30 further includes a third connecting oil passage L7 connecting the inlet of the diverter valve and the first outlet. A check valve 34 is installed on the third connecting oil passage L7, with the flow direction of the check valve 34 from the first outlet of the diverter valve 31 to the inlet. When the boom cylinder 10 retracts, the first working oil passage L1 supplies oil to the rod chamber of the boom, and the hydraulic oil in the hydraulic tank flows into the first working oil passage L1 through the check valve 34. Furthermore, under this condition, the pressure transmitted to the rod chamber and rodless chamber of the bucket cylinder 20 is the same; therefore, the hydraulic oil will not be diverted to the bucket cylinder 20, and the bucket cylinder 20 remains stationary.

[0059] In the third embodiment, as Figure 3 The diagram shows the hydraulic principle of the hydraulic control system according to the third embodiment of this utility model. The oil inlet of the leveling switch valve 40 is connected to the first connecting oil circuit L5. With the above structure, the leveling switch valve 40 can control the flow direction of the hydraulic oil flowing from the second outlet of the diverter valve 31 to relieve pressure on the first working oil circuit L1. When the leveling switch valve 40 is open, the hydraulic oil flowing from the second outlet of the diverter valve 31 can flow back to the hydraulic oil tank after passing through the leveling switch valve 40. At this time, the hydraulic oil in the first working oil circuit L1 will also flow to the hydraulic oil tank in two separate paths, thereby relieving pressure on the first working oil circuit L1. This design provides another flexible control method, making the operation of the skid steer loader more convenient and efficient under different working conditions.

[0060] In one embodiment, the leveling switch valve 40 is a normally closed two-position two-way solenoid valve. In most operating conditions, the bucket moves together with the boom to perform loading and transport functions. Therefore, in the three embodiments described above, setting the leveling switch valve 40 to a normally closed type allows for coordinated movement of the boom and bucket when no operational control is required, improving work efficiency. When the boom needs to move upwards independently, simply sending an opening signal to the leveling switch valve 40 via the electronic control system quickly depressurizes the first working hydraulic circuit L1, allowing the boom to move independently. This design not only simplifies the operation process and extends the service life of the leveling switch valve 40, but also improves the response speed of the skid steer loader.

[0061] In the fourth embodiment, such as Figure 4 The diagram shown is a hydraulic schematic of a hydraulic control system according to a fourth embodiment of the present invention. The hydraulic control system includes: an oil supply circuit, comprising a first working oil circuit L1 and a second working oil circuit L2; a boom cylinder 10, the rod-side chamber of which is connected to the first working oil circuit L1; a bucket cylinder 20, the rodless chamber of which is connected to the second working oil circuit L2; and a leveling valve assembly 30, the first port of which is connected to the first working oil circuit L1, the second port of which is connected to the second working oil circuit L2, and the third port of which is connected to the hydraulic oil tank. The leveling valve assembly 30 is used to divert hydraulic oil from the first working oil circuit L1 to the second working oil circuit L2 and the hydraulic oil tank. The leveling valve assembly 30 includes a leveling switch valve 40, which is used to open or close the oil passage between the first and second ports.

[0062] In the fourth embodiment, the leveling switch valve 40 is located within the leveling valve assembly 30, resulting in a more compact structure that effectively saves space and improves the integration of the entire hydraulic control system. The position of the leveling switch valve 40 within the leveling valve assembly 30 is carefully designed to ensure accurate control of the oil flow between the first and second ports. When the boom needs to move upwards independently, the electronic control system sends a closing signal to the leveling switch valve 40, which responds quickly, closing the oil flow and preventing hydraulic oil in the first working oil circuit L1 from flowing to the second port and the second working oil circuit L2. Conversely, when coordinated boom and bucket movements are required, the electronic control system sends an opening signal to the leveling switch valve 40, which opens, allowing hydraulic oil in the first working oil circuit L1 to flow smoothly to the second port and the second working oil circuit L2, thereby driving the bucket cylinder 20 to extend and achieving coordinated boom and bucket movements. This design not only simplifies the structure of the hydraulic control system but also improves its reliability and response speed.

[0063] In one embodiment, such as Figure 4As shown, the leveling valve assembly 30 further includes a flow divider valve 31, which has a flow divider valve inlet, a first outlet, and a second outlet. The flow divider valve inlet is connected to the first working oil circuit L1, the first outlet is connected to the hydraulic oil tank, and the second outlet is connected to the second working oil circuit L2. The leveling switch valve 40 is connected to the second connecting oil circuit L6 between the second outlet and the second working oil circuit L2. Using the above-mentioned leveling valve assembly 30, when oil is discharged from the rod chamber of the boom cylinder 10, the hydraulic oil first enters the flow divider valve 31. The flow divider valve 31 distributes the hydraulic oil to the first outlet and the second outlet according to a preset ratio. The hydraulic oil from the first outlet flows back to the hydraulic oil tank, achieving partial pressure relief; while the hydraulic oil from the second outlet continues to flow to the second working oil circuit L2 to drive the bucket cylinder 20 to extend. The leveling switch valve 40 is located on the second connecting oil circuit L6 between the second oil outlet and the second working oil circuit L2, and is used to control the flow direction of the hydraulic oil in this section. When the boom needs to move upward independently, the leveling switch valve 40 closes, cutting off the second connecting oil circuit L6, preventing the hydraulic oil from the second oil outlet from continuing to flow to the second working oil circuit L2, thus enabling the boom to move independently. When the boom and bucket need to move in coordination, the leveling switch valve 40 opens, allowing the hydraulic oil from the second oil outlet to flow smoothly to the second working oil circuit L2 to drive the bucket cylinder 20 to extend, achieving synchronous movement of the boom and bucket. This design not only ensures the stability and reliability of the hydraulic control system, but also improves its flexibility and adaptability, enabling the skid steer loader to better meet the operational needs under different working conditions.

[0064] In one embodiment, the leveling switch valve 40 is a normally open two-position two-way solenoid valve. In the fourth embodiment described above, the leveling switch valve 40, as a normally open solenoid valve, can maintain the oil circuit conduction state when there is no control signal, allowing the boom and bucket to move in coordination under most circumstances, meeting the needs of conventional operations such as loading and handling. When the boom needs to move upward independently, the electronic control system sends a closing signal to the leveling switch valve 40, which responds quickly, cutting off the oil circuit and preventing the hydraulic oil from the second outlet from flowing to the second working oil circuit L2, thereby achieving independent boom movement. This normally open design allows the skid steer loader to maintain coordinated boom and bucket movement without additional control during normal operation, improving work efficiency. Simultaneously, when independent boom movement is required, only a closing signal needs to be sent, making the operation process simple and quick.

[0065] In one embodiment, a skid steer loader is provided, including the hydraulic control system described above.

[0066] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0067] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0069] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydraulic control system, characterized in that, include: The oil supply circuit includes a first working oil circuit (L1) and a second working oil circuit (L2); Boom cylinder (10), the rod chamber of the boom cylinder (10) is connected to the first working oil circuit (L1); Bucket cylinder (20), the rodless chamber of the bucket cylinder (20) is connected to the second working oil circuit (L2); The leveling valve assembly (30) has a first oil port connected to the first working oil circuit (L1), a second oil port connected to the second working oil circuit (L2), and a third oil port connected to the hydraulic oil tank. When oil is discharged from the rod chamber of the boom cylinder (10), the leveling valve assembly (30) is used to divert the hydraulic oil of the first working oil circuit (L1) to the second working oil circuit (L2) and the hydraulic oil tank. The leveling switch valve (40) is connected to the hydraulic oil tank at its oil outlet end. The leveling switch valve (40) is used to depressurize the first working oil circuit (L1).

2. The hydraulic control system according to claim 1, characterized in that, The oil inlet of the leveling switch valve (40) is connected to the working oil circuit between the rod chamber of the boom cylinder (10) and the first oil port.

3. The hydraulic control system according to claim 1, characterized in that, The oil inlet of the leveling switch valve (40) is connected to the second working oil circuit (L2).

4. The hydraulic control system according to claim 1, characterized in that, The leveling valve assembly (30) includes: The flow divider valve (31) has a flow divider valve inlet, a first outlet and a second outlet. The flow divider valve inlet is connected to the first working oil circuit (L1), the first outlet is connected to the hydraulic oil tank, and the second outlet is connected to the second working oil circuit (L2).

5. The hydraulic control system according to claim 4, characterized in that, The second oil outlet is connected to the second working oil circuit (L2) by a first connecting oil circuit (L5), and the oil inlet of the leveling switch valve (40) is connected to the first connecting oil circuit (L5).

6. The hydraulic control system according to any one of claims 1 to 5, characterized in that, The leveling switch valve (40) is a normally closed two-position two-way solenoid valve.

7. A hydraulic control system, characterized in that, include: The oil supply circuit includes a first working oil circuit (L1) and a second working oil circuit (L2); Boom cylinder (10), the rod chamber of the boom cylinder (10) is connected to the first working oil circuit (L1); Bucket cylinder (20), the rodless chamber of the bucket cylinder (20) is connected to the second working oil circuit (L2); The leveling valve assembly (30) has a first port connected to the first working oil circuit (L1), a second port connected to the second working oil circuit (L2), and a third port connected to the hydraulic oil tank. The leveling valve assembly (30) is used to divert the hydraulic oil from the first working oil circuit (L1) to the second working oil circuit (L2) and the hydraulic oil tank. The leveling valve assembly (30) includes a leveling switch valve (40), which is used to open or close the oil circuit between the first port and the second port.

8. The hydraulic control system according to claim 7, characterized in that, The leveling valve assembly (30) also includes: The diverter valve (31) has a diverter valve inlet, a first outlet and a second outlet. The diverter valve inlet is connected to the first working oil circuit (L1), the first outlet is connected to the hydraulic oil tank, and the second outlet is connected to the second working oil circuit (L2). The leveling switch valve (40) is connected to the second connecting oil circuit (L6) between the second outlet and the second working oil circuit (L2).

9. The hydraulic control system according to claim 7 or 8, characterized in that, The leveling switch valve (40) is a normally open two-position two-way solenoid valve.

10. A skid steer loader, characterized in that, The hydraulic control system includes any one of claims 1 to 9.

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