Hydraulic system driven by hydraulic motor

Abstract

The hydraulic system driven by the hydraulic motor comprises an oil supply pipeline, an oil return pipeline, a switching valve, a motor control valve and a working motor, the oil supply pipeline is connected with the switching valve, a first outlet of the switching valve is connected with a pressure oil port of the motor control valve, an oil return port of the motor control valve is connected with the oil return pipeline, and a second outlet of the switching valve is connected with the working motor. A working port A and a working port B of the motor control valve are respectively connected with two ends of the working motor; and the second outlet of the switching valve is provided with an external oil conveying pipeline. According to the utility model, oil is supplied to the motor control valve through the oil supply pipeline, and the motor control valve controls the hydraulic oil flow direction or oil return of the working motor, so that the driving of the working motor is realized; when the tractor is switched to perform combined operation, only an external oil conveying pipeline needs to be connected with a driving equipment hydraulic unit in a corresponding form, and the working state of the switching valve is changed, so that oil supply of driving equipment in other forms can be taken into account conveniently; a matched hydraulic system does not need to be replaced.

Description

Technical Field

[0001] The utility model relates to the technical field of tractor implement hydraulic systems, in particular to a hydraulic system driven by a hydraulic motor. Background Art

[0002] Through integration with various implements, the application scope of tractors continues to expand, broadening the market for tractors as main machines. The emergence and deployment of increasingly diverse implements, such as weeding, pruning, spraying, tilling, and traction, has placed higher demands on tractors as main machines. Implements, as auxiliary working devices attached to the tractor, come in various configurations, including cylinder-controlled and motor-controlled, and their functionality is becoming increasingly diverse.

[0003] Currently, when a tractor needs to operate in combination with different types of implements, in order for the tractor to provide power to the implements, the corresponding type of drive device must be switched accordingly. Different drive devices have different hydraulic oil supply methods. For example, a motor provides one-way continuous oil supply, while a cylinder provides round-trip oil supply, with a limited total amount per trip. Therefore, a tractor equipped with a motor as an implement drive device cannot also provide oil supply for other types of drive devices. When switching to a different type of drive implement, not only does the drive device need to be switched, but the supporting hydraulic system also needs to be replaced. This is not only cumbersome to operate, but also requires high professional skills from the person making the change, limiting the promotion and application of diversified tractor implements. Utility Model Content

[0004] The technical problem to be solved by the utility model is: how to take into account the oil supply of other forms of driving equipment while driving the hydraulic motor.

[0005] The technical solution of the utility model to solve the above technical problems is as follows:

[0006] The utility model provides a hydraulic motor driven hydraulic system, comprising an oil supply pipeline, an oil return pipeline, a switching valve, a motor control valve, and a working motor, wherein the oil supply pipeline is connected to the switching valve, a first outlet of the switching valve is connected to a pressure oil port of the motor control valve, an oil return port of the motor control valve is connected to the oil return pipeline, a working port A and a working port B of the motor control valve are respectively connected to two ends of the working motor; and an external oil circuit is provided at the second outlet of the switching valve.

[0007] The beneficial effects of the utility model are:

[0008] By adopting the utility model, oil is supplied to the motor control valve through the oil supply pipeline, and the motor control valve controls the hydraulic oil flow direction or oil return of the working motor, thereby realizing the driving of the working motor; at the same time, through the switching valve, while controlling the oil supply or oil cut-off to the motor control valve, the oil supply or oil cut-off of the external oil circuit can also be independently controlled. When the tractor switches the implement combination operation, it is only necessary to connect the hydraulic unit of the corresponding form of the driving equipment through the external oil circuit and change the working state of the switching valve, so as to facilitate the oil supply of other forms of driving equipment; there is no need to replace the supporting hydraulic system, the operation is convenient, and ordinary users can also complete the operation efficiently, with low cost, which is convenient for the promotion and application of diversified implements of tractors.

[0009] On the basis of the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, it also includes an unloading valve, the inlet of the unloading valve is connected to the oil supply pipeline, and the outlet of the unloading valve is connected to the oil return pipeline.

[0011] When the motor is moving, if a sudden change in external load causes a sharp fluctuation in pressure, the unloading valve can be opened at this time, and the pressure oil will be directly returned to the return oil pipeline through the unloading valve, thereby achieving the purpose of limiting the pressure and protecting the hydraulic system.

[0012] Furthermore, one end of the valve core of the unloading valve is connected to its own inlet oil circuit, and the direction of the oil pressure from its own inlet oil circuit on the valve core of the unloading valve is opposite to the direction of the reset elastic force of the valve core; the unloading valve is a normally closed valve.

[0013] When the pressure fluctuates violently, the oil pressure can be used to automatically push the unloading valve to open, thereby achieving the purpose of limiting the pressure with good sensitivity.

[0014] Furthermore, it also includes a pilot oil circuit and a pilot safety valve, one end of the pilot oil circuit is connected to the oil supply pipeline, the other end of the pilot oil circuit is connected to the inlet end of the pilot safety valve through a first branch, the outlet end of the pilot safety valve is connected to the return oil pipeline, and one end of the valve core of the pilot safety valve is connected to its own inlet oil circuit; the other end of the pilot oil circuit is connected to the other end of the valve core of the unloading valve through a second branch; a first throttling element is provided on the pilot oil circuit.

[0015] When overpressure occurs, the pilot safety valve can automatically control the unloading valve to open, thereby limiting the pressure and improving safety. When the pressure recovers, the pilot safety valve and the unloading valve can automatically reset, ensuring the stable operation of the hydraulic system and good reliability. During normal operation, the oil pressures at both ends of the valve core of the unloading valve are balanced with each other, and are not affected by the pressure of the oil supply pipeline. It can adapt to any working pressure and has good adaptability.

[0016] Furthermore, the first throttling element is a throttling hole.

[0017] Simple structure and long service life.

[0018] Furthermore, it also includes an external transmission safety valve, the inlet of the external transmission safety valve is connected to the external oil line, and the outlet of the external transmission safety valve is connected to the return oil line.

[0019] When the external oil line is connected to the hydraulic unit of other driving equipment, the pressure from the second outlet of the switching valve to the external oil line is limited by the external safety valve, which is convenient for protecting the hydraulic units of other driving equipment and improving safety; at the same time, it avoids the influence of the hydraulic units of other driving equipment on the working motor.

[0020] Furthermore, the switching valve is provided with a first inlet and a second inlet, the oil supply pipeline connects the first inlet and the second inlet of the switching valve through a branch, and a second throttling element is provided on the pipeline of the second inlet; the first outlet of the switching valve corresponds to the first inlet, and the second outlet of the switching valve corresponds to the second inlet.

[0021] It is convenient to make the first outlet and the second outlet of the switching valve have independent passages, and the reliability is good; under the action of the second throttling element, it is convenient to give priority to the operation of the working motor, thereby ensuring the working stability of the working motor.

[0022] Furthermore, the second throttling element is a throttling hole.

[0023] Simple structure and long service life.

[0024] Furthermore, one end of the valve core of the switching valve is connected to the pipeline of its first inlet, and the other end of the valve core of the switching valve is connected to the pipeline of its second inlet.

[0025] Under the action of the second throttling element, when oil is discharged from the second outlet of the switching valve, there is a pressure difference at both ends of the valve core of the switching valve, and the pressure difference is proportional to the flow rate of the second outlet; when the flow rate of the external oil circuit is too large, the pressure difference at both ends of the valve core of the switching valve increases, and pushes the valve core of the switching valve to move to the first outlet to discharge oil, so as to facilitate the return of part of the pressurized oil to the return oil pipeline, thereby avoiding overpressure or excessive movement of the driving equipment controlled by the external oil circuit to cause collision.

[0026] Furthermore, the valve core of the motor control valve is provided with an oil return position and a motor position. When the oil return position is working, the pressure oil port, working port A and working port B of the motor control valve are all connected to their own oil return port; when the motor position is working, one of the working port A and working port B of the motor control valve is connected to its own pressure oil port, and the other is connected to its own oil return port; the normal state of the motor control valve is that it works in the oil return position.

[0027] When the working motor is not working, it is convenient to relieve the pressure of the pipeline where the working motor is located, and at the same time, the oil from the first outlet of the switching valve is directly returned to the return oil pipeline, avoiding affecting the working motor and improving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a structural diagram of the utility model in its initial state.

[0029] Figure 2 This is a structural diagram of the motor of the utility model in working state.

[0030] Figure 3 This is a structural diagram of the utility model in a safe unloading state.

[0031] In the accompanying drawings, the technical features represented by the reference numerals are as follows:

[0032] 1- Main control valve; 2- Oil supply line; 3- Oil return line; 4- Switching valve; 5- Motor control valve; 6- Working motor; 7- External oil line; 8- Unloading valve; 9- Pilot safety valve; 10- First throttling element; 11- External safety valve; 12- Second throttling element. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0034] This utility model refers to Figure 1-3 .

[0035] The utility model provides a hydraulic motor driven hydraulic system, comprising an oil supply pipeline 2, an oil return pipeline 3, a switching valve 4, a motor control valve 5, and a working motor 6, wherein the oil supply pipeline 2 is connected to the switching valve 4, a first outlet of the switching valve 4 is connected to a pressure oil port of the motor control valve 5, an oil return port of the motor control valve 5 is connected to the oil return pipeline 3, a working port A and a working port B of the motor control valve 5 are respectively connected to two ends of the working motor 6; and an external oil pipeline 7 is provided at the second outlet of the switching valve 4.

[0036] principle:

[0037] Both the switching valve 4 and the motor control valve 5 are directional valves. The common nomenclature for directional valve interfaces is port A, port B, port P, and port T. Generally, ports A and B are working oil ports, used to connect to the hydraulic components they control; port P is the pressure oil port for incoming pressure oil, and port T is the return oil port for returning oil. The directional valve operates in specific positions by moving its spool, creating specific connections between ports A, B, P, and T through these specific positions, thereby changing the valve's operating state.

[0038] During installation, the oil supply line 2 is connected to the pressure oil outlet of the main control valve 1 on the tractor, and the oil return line 3 is connected to the return oil inlet of the main control valve 1. The main control valve 1 is a conventional component on tractors. The pressure oil inlet of the main control valve 1 is connected to a pressure oil source such as a hydraulic pump, and the return oil outlet of the main control valve 1 is connected to the fuel tank.

[0039] After installation, it has the following status, such as Figure 1-3 As shown (the direction of the arrow is the direction of oil flow):

[0040] In the initial state, if Figure 1 As shown, switching valve 4 is in the first outlet state, with the pressure oil port, working port A, and working port B of motor control valve 5 all connected to the oil return port. After entering switching valve 4, pressurized oil flows from the first outlet of switching valve 4 to the pressure oil port of motor control valve 5, then to the oil return port of motor control valve 5, and finally to oil return line 3. Switching valve 4 can also be switched to the second outlet state, allowing external oil line 7 to connect to the cylinder hydraulic system, thereby also accommodating the supply of other types of drive equipment.

[0041] When the motor is working, Figure 2 As shown, the switching valve 4 is in the oil-discharging state through its first outlet. One of the working ports A and B of the motor control valve 5 is connected to its own pressure port, while the other is connected to its own return port. After the pressure oil enters the switching valve 4, the flow path is: the first outlet of the switching valve 4 → the pressure port of the motor control valve 5 → the working ports B / A of the motor control valve 5 → the working motor 6 → the working ports A / B of the motor control valve 5 → the return port of the motor control valve 5 → the return port of the motor control valve 5 → the return oil line 33. Alternatively, the switching valve 4 can be switched to a state where both the first and second outlets are simultaneously discharging oil. The external oil line 7 can be connected to a cylinder hydraulic system, thereby also accommodating the supply of oil to other types of drive equipment.

[0042] By adopting the utility model, oil is supplied to the motor control valve 5 through the oil supply pipeline 2, and the motor control valve 5 controls the flow direction or return of the hydraulic oil of the working motor 6, thereby realizing the driving of the working motor 6; at the same time, through the switching valve 4, while controlling the oil supply or oil cut-off to the motor control valve 5, the oil supply or oil cut-off of the external oil circuit 7 can also be independently controlled. When the tractor switches the combination of implements for operation, it is only necessary to connect the hydraulic unit of the corresponding form of the driving equipment through the external oil circuit 7 and change the working state of the switching valve 4, so as to facilitate the oil supply of other forms of driving equipment; there is no need to replace the supporting hydraulic system, the operation is convenient, and ordinary users can also complete the operation efficiently, with low cost, which is convenient for the promotion and application of diversified implements of tractors.

[0043] Furthermore, it also includes an unloading valve 8 , the inlet of the unloading valve 8 is connected to the oil supply pipeline 2 , and the outlet of the unloading valve 8 is connected to the oil return pipeline 3 .

[0044] like Figure 3As shown: when the motor is moving, if the sudden change of external load causes a sharp fluctuation in pressure, the unloading valve 8 can be opened at this time, and the pressure oil will be directly returned to the return oil pipeline 3 through the unloading valve 8, so as to achieve the purpose of limiting the pressure and protect the hydraulic system.

[0045] Furthermore, one end of the valve core of the unloading valve 8 is connected to its own inlet oil circuit, and the direction of the oil pressure from its own inlet oil circuit on the valve core of the unloading valve 8 is opposite to the direction of the reset elastic force of the valve core; the unloading valve 8 is a normally closed valve.

[0046] Note: The normally closed valve is a conventional product. A return spring is installed at the other end of the valve core to provide the valve core's return force. When the oil pressure at one end of the normally closed valve core exceeds the return spring's force, the oil pressure pushes the normally closed valve open. When the oil pressure is less than the return spring's force, the return spring pushes the valve core closed.

[0047] When the pressure fluctuates violently, the oil pressure can be used to automatically push the unloading valve 8 to open, thereby achieving the purpose of limiting the pressure with good sensitivity.

[0048] Furthermore, it also includes a pilot oil circuit and a pilot safety valve 9, one end of the pilot oil circuit is connected to the oil supply pipeline 2, the other end of the pilot oil circuit is connected to the inlet end of the pilot safety valve 9 through a first branch, the outlet end of the pilot safety valve 9 is connected to the return oil pipeline 3, and one end of the valve core of the pilot safety valve 9 is connected to its own inlet oil circuit; the other end of the pilot oil circuit is connected to the other end of the valve core of the unloading valve 8 through a second branch; a first throttling element 10 is provided on the pilot oil circuit.

[0049] Note: During normal operation, the pilot safety valve 9 is closed, and the pressure in the pilot oil circuit and the pressure at both ends of the valve core of the unloading valve 8 are essentially equal to the pressure in the oil supply line 2. The valve core of the unloading valve 8 remains stationary; the unloading valve 8 remains in its initial closed state. When a sudden change in external load causes a sharp fluctuation in pressure, the pressure in the oil supply line 2 increases sharply, pushing the valve core of the pilot safety valve 9 to move, causing the pilot safety valve 9 to open. When the pilot safety valve 9 opens, under the pressure-reducing effect of the first throttling element 10, a pressure differential exists at both ends of the valve core of the unloading valve 8 in the opposite direction of its own restoring spring force. This pressure differential overcomes the restoring spring force of the valve core of the unloading valve 8, pushing the valve core to move until the unloading valve 8 opens, and the pressurized oil flows directly back to the return oil line 3 through the unloading valve 8. When the pressure of the oil supply pipeline 2 is restored, the pressure of the oil supply pipeline 2 is insufficient to continue to overcome the valve core reset spring force of the pilot safety valve 9, the pilot safety valve 9 returns to the closed normal state, the pressure difference at both ends of the valve core of the unloading valve 8 disappears, the valve core of the unloading valve 8 is reset under its own reset spring force, and the unloading valve 8 returns to the closed normal state.

[0050] When overpressure occurs, the pilot safety valve 9 can automatically control the unloading valve 8 to open, thereby achieving the effect of limiting pressure and improving safety; when pressure is restored, the pilot safety valve 9 and the unloading valve 8 can automatically reset, ensuring the stable operation of the hydraulic system and good reliability; during normal operation, the oil pressures at both ends of the valve core of the unloading valve 8 are balanced with each other, are not affected by the pressure of the oil supply pipeline 2, can adapt to any working pressure, and have good adaptability.

[0051] Furthermore, the first throttling element 10 is a throttling hole.

[0052] Simple structure and long service life.

[0053] Furthermore, it also includes an external transmission safety valve 11 , the inlet of the external transmission safety valve 11 is connected to the external oil line 7 , and the outlet of the external transmission safety valve 11 is connected to the return oil line 3 .

[0054] When the external oil circuit 7 is connected to the hydraulic units of other driving devices, the pressure from the second outlet of the switching valve 4 to the external oil circuit 7 is limited by the external safety valve 11, which is convenient for protecting the hydraulic units of other driving devices and improving safety; at the same time, it avoids the influence of the hydraulic units of other driving devices on the working motor 6.

[0055] Furthermore, the switching valve 4 is provided with a first inlet and a second inlet, the oil supply line 2 is connected to the first inlet and the second inlet of the switching valve 4 through a branch, and a second throttling element 12 is provided on the pipeline of the second inlet; the first outlet of the switching valve 4 corresponds to the first inlet, and the second outlet of the switching valve 4 corresponds to the second inlet.

[0056] Note: In the initial state and when the motor is working, the first outlet of the switching valve 4 is connected to the first inlet; when oil is supplied to other hydraulic systems, the second outlet is connected to the second inlet.

[0057] It is convenient to make the first outlet and the second outlet of the switching valve 4 have independent passages, and the reliability is good; under the action of the second throttling element 12, it is convenient to give priority to the operation of the working motor 6, thereby ensuring the working stability of the working motor 6.

[0058] Furthermore, the second throttling element 12 is a throttling hole.

[0059] Simple structure and long service life.

[0060] Furthermore, one end of the valve core of the switching valve 4 is connected to the pipeline of its first inlet, and the other end of the valve core of the switching valve 4 is connected to the pipeline of its second inlet.

[0061] Under the action of the second throttling element 12, when oil is discharged from the second outlet of the switching valve 4, there is a pressure difference at both ends of the valve core of the switching valve 4, and the pressure difference is proportional to the flow rate of the second outlet; when the flow rate of the external oil circuit 7 is too large, the pressure difference at both ends of the valve core of the switching valve 4 increases, and pushes the valve core of the switching valve 4 to move to the first outlet to discharge oil, so as to facilitate the return of part of the pressurized oil to the return oil pipeline 3, thereby avoiding overpressure or excessive movement of the driving equipment controlled by the external oil circuit 7 to cause collision.

[0062] Furthermore, the valve core of the motor control valve 5 is provided with an oil return position and a motor position. When the oil return position is working, the pressure oil port, working port A and working port B of the motor control valve 5 are all connected to their own oil return port; when the motor position is working, one of the working port A and working port B of the motor control valve 5 is connected to its own pressure oil port, and the other is connected to its own oil return port; the normal state of the motor control valve 5 is that it works at the oil return position.

[0063] Note: In addition to the embodiment shown in the drawings, two opposite motor positions can also be set.

[0064] When the working motor 6 is not working, it is convenient to relieve the pressure of the pipeline where the working motor 6 is located, and at the same time, the oil from the first outlet of the switching valve 4 directly flows back to the return oil pipeline 3, avoiding affecting the working motor 6 and improving safety.

[0065] In the description of the present invention, it should be understood that if there are descriptive terms indicating orientation, direction or positional relationship, such as: "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated in this specification is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of understanding the present invention and simplifying the description, and does not indicate or imply that the referred part, element or whole must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0066] In addition, if there are order description terms, such as "first", "second", etc., their use in this specification is to facilitate understanding or simplify the description. For example, in order to distinguish multiple technical features with the same type or function, but they have to be mentioned separately, this specification may use prefix or suffix order description terms to distinguish them. Therefore, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of such features. In the description of this utility model, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0067] In the present invention, if terms describing the relative functional relationship of structures are used, such as "install", "connect", "connect", "fix", etc., they should be understood in a broad sense unless otherwise clearly specified and limited. For example, "install", "connect", "connect", etc. can be fixed connections, detachable connections, or integrated; can be mechanical connections or electrical connections; can be direct connections or indirect connections through an intermediate medium, can be internal connections between two elements or interactive relationships between two elements; "fix" can be fixed to form an integral body, or can be detachably fixed through fasteners; can be directly fixed or fixed through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above-mentioned descriptive terms in the present invention can be understood according to the specific circumstances, the context, the coherence of the preceding and following texts, etc.

[0068] In this utility model, if descriptive terms with ancillary or connecting meaning appear, for example, a first feature being "on" or "below" a second feature, these should not be interpreted as limiting unless otherwise expressly specified or limited. For example, "on" or "below" may refer to direct contact between the first and second features, or indirect contact between the first and second features through an intermediary. Those skilled in the art will understand the specific meanings of these descriptive terms in this utility model based on the specific circumstances, context, and coherence of the preceding and following texts.

[0069] Furthermore, when a first feature is “above,” “above,” or “above” a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. When a first feature is “below,” “below,” or “below” a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0070] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments, examples and features of different embodiments and examples described in this specification, unless there is any contradiction, and these combinations or combinations should all fall within the scope summarized by the present invention.

[0071] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are illustrative and cannot be understood as limiting the present invention. Changes, modifications, substitutions and variations of the above embodiments made by ordinary technicians in the field within the scope of information available from public channels and in combination with the technical inspiration given by the application documents are still within the scope of protection of the present application.

Claims

1. A hydraulic motor driven hydraulic system, characterized in that: The invention comprises an oil supply pipeline (2), an oil return pipeline (3), a switching valve (4), a motor control valve (5), and a working motor (6); the oil supply pipeline (2) is connected to the switching valve (4); the first outlet of the switching valve (4) is connected to the pressure oil port of the motor control valve (5); the oil return port of the motor control valve (5) is connected to the oil return pipeline (3); the working port A and the working port B of the motor control valve (5) are respectively connected to the two ends of the working motor (6); and the second outlet of the switching valve (4) is provided with an external oil transmission pipeline (7).

2. The hydraulic motor driven hydraulic system according to claim 1, characterized in that: The unloading valve (8) is also included. The inlet of the unloading valve (8) is connected to the oil supply pipeline (2), and the outlet of the unloading valve (8) is connected to the oil return pipeline (3).

3. The hydraulic motor driven hydraulic system according to claim 2, characterized in that: One end of the valve core of the unloading valve (8) is connected to its own inlet oil circuit, and the direction of the oil pressure from its own inlet oil circuit to which the valve core of the unloading valve (8) is subjected is opposite to the direction of the resetting elastic force of the valve core; the unloading valve (8) is a normally closed valve.

4. The hydraulic motor driven hydraulic system according to claim 3, characterized in that: The invention also includes a pilot oil circuit and a pilot safety valve (9), wherein one end of the pilot oil circuit is connected to the oil supply pipeline (2), the other end of the pilot oil circuit is connected to the inlet end of the pilot safety valve (9) through a first branch, the outlet end of the pilot safety valve (9) is connected to the oil return pipeline (3), one end of the valve core of the pilot safety valve (9) is connected to its own inlet oil circuit; the other end of the pilot oil circuit is connected to the other end of the valve core of the unloading valve (8) through a second branch; and a first throttling element (10) is provided on the pilot oil circuit.

5. The hydraulic motor driven hydraulic system according to claim 4, characterized in that: The first throttling element (10) is a throttling hole.

6. The hydraulic motor driven hydraulic system according to claim 1, characterized in that: It also includes an external transmission safety valve (11), the inlet of the external transmission safety valve (11) is connected to the external transmission oil line (7), and the outlet of the external transmission safety valve (11) is connected to the return oil line (3).

7. The hydraulic motor driven hydraulic system according to claim 1, characterized in that: The switching valve (4) is provided with a first inlet and a second inlet, the oil supply pipeline (2) is connected to the first inlet and the second inlet of the switching valve (4) through a branch, and a second throttling element (12) is provided on the pipeline of the second inlet; the first outlet of the switching valve (4) corresponds to the first inlet, and the second outlet of the switching valve (4) corresponds to the second inlet.

8. The hydraulic motor driven hydraulic system according to claim 7, characterized in that: The second throttling element (12) is a throttling hole.

9. The hydraulic motor driven hydraulic system according to claim 7, characterized in that: One end of the valve core of the switching valve (4) is connected to the pipeline of its own first inlet, and the other end of the valve core of the switching valve (4) is connected to the pipeline of its own second inlet.

10. The hydraulic motor driven hydraulic system according to claim 1, characterized in that: The valve core of the motor control valve (5) is provided with an oil return position and a motor position. When the oil return position is in operation, the pressure oil port, the working port A and the working port B of the motor control valve (5) are all connected to the own oil return port. When the motor position is in operation, one of the working port A and the working port B of the motor control valve (5) is connected to the own pressure oil port, and the other is connected to the own oil return port. The normal state of the motor control valve (5) is that it is in operation at the oil return position.

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