A conveying arm valve group and a conveying arm hydraulic control system

Abstract

The present invention relates to a conveying arm valve group, which includes a first two-position two-way solenoid valve and a second two-position two-way solenoid valve. The oil inlet P port of the valve group is connected to the oil inlet of the first two-position two-way solenoid valve, the oil inlet of the second two-position two-way solenoid valve, and the oil inlet of the conveying arm fan motor. The oil outlet of the first two-position two-way solenoid valve is connected to the oil return T port of the valve group. The oil outlet of the second two-position two-way solenoid valve is connected to the oil inlet of the first conveying arm motor and the second conveying arm motor. The oil return port of the conveying arm fan motor is connected to the oil inlet of the first conveying arm motor and the second conveying arm motor. The oil return port of the first conveying arm motor and the second conveying arm motor is connected to the oil return T port of the valve group. The conveying arm valve group and conveying arm hydraulic control system provided by the present invention utilize a proportional solenoid valve combination for precisely controlled actuators, thereby improving controllability and being energy-saving and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural machinery, and in particular to a conveying arm valve group and a conveying arm hydraulic control system of a sugarcane harvester. Background Art

[0002] The conveyor arm is a crucial component of a sugarcane harvester. The cut sugarcane is transported to the transfer vehicle via a rotating chain rake on the conveyor arm. When harvesting large quantities of sugarcane simultaneously, the primary fan is unable to remove impurities such as dirt, grass, and leaves mixed in with the sugarcane. In this case, the secondary fan on the conveyor arm provides secondary impurity removal, significantly reducing the impurity content and improving the quality of the harvested sugarcane.

[0003] The control conveying arm valve group currently on the market has the following problems:

[0004] The degree of integration is not high, and there are problems such as large valve block size, inconvenient installation and many control points, which result in high cost defects; the control logic is relatively complex, difficult to operate and poses a safety hazard. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a conveying arm valve group and a conveying arm hydraulic control system for a sugarcane harvester in view of the above-mentioned shortcomings.

[0006] The present invention is achieved through the following technical solutions:

[0007] A conveying arm valve group, which includes a first two-position two-way solenoid valve and a second two-position two-way solenoid valve, the oil inlet P port of the valve group is connected to the oil inlet of the first two-position two-way solenoid valve, the oil inlet of the second two-position two-way solenoid valve and the oil inlet of the conveying arm fan motor, the oil outlet of the first two-position two-way solenoid valve is connected to the return oil T port of the valve group, the oil outlet of the second two-position two-way solenoid valve is connected to the oil inlet of the first conveying arm motor and the second conveying arm motor, the return oil port of the conveying arm fan motor is connected to the oil inlet of the first conveying arm motor and the second conveying arm motor, and the return oil port of the first conveying arm motor and the second conveying arm motor is connected to the return oil T port of the valve group.

[0008] Furthermore, the described conveying arm valve group also includes a first two-position three-way solenoid valve and a two-position four-way hydraulic control valve, the oil inlet of the first two-position three-way solenoid valve is connected to the oil outlet of the second two-position two-way solenoid valve, and the oil outlet of the first two-position three-way solenoid valve is connected to the return oil port of the first conveying arm motor and the second conveying arm motor through the two-position four-way hydraulic control valve.

[0009] Furthermore, the described conveying arm valve group also includes a second two-position three-way solenoid valve, the oil inlet P port of the valve group is connected to the oil inlet of the second two-position three-way solenoid valve, and the first oil outlet of the second two-position three-way solenoid valve is connected to the oil return T port of the valve group; the second oil outlet of the second two-position three-way solenoid valve is connected to the oil inlet of the first three-position four-way proportional solenoid valve, the oil outlet of the first three-position four-way proportional solenoid valve is connected to the oil inlet of the second three-position four-way proportional solenoid valve, the oil outlet of the second three-position four-way proportional solenoid valve is connected to the oil inlet of the third three-position four-way proportional solenoid valve, and the oil outlet of the third three-position four-way proportional solenoid valve is connected to the oil return T port of the valve group.

[0010] Furthermore, in the conveying arm valve group, a priority flow valve is provided between the oil inlet P port of the valve group and the oil inlet port of the second two-position three-way solenoid valve.

[0011] Furthermore, in the described conveying arm valve group, the first three-position four-way proportional solenoid valve is connected to the conveying arm fan rotating motor, the second three-position four-way proportional solenoid valve is connected to the conveying arm tail unloading cylinder, and the third three-position four-way proportional solenoid valve is connected to the conveying arm lifting cylinder.

[0012] Furthermore, in the conveying arm valve group, a first overflow valve is arranged between the oil inlet P port of the valve group and the oil return T port of the valve group, a second overflow valve is arranged between the first oil outlet of the second two-position three-way solenoid valve and the oil return T port of the valve group, and a third overflow valve is arranged between the oil inlet and the oil outlet of the second two-position two-way solenoid valve.

[0013] Furthermore, in the conveying arm valve group, the overflow pressure of the second overflow valve and the third overflow valve is 1.5 MPa lower than that of the first overflow valve.

[0014] Furthermore, in the conveying arm valve group, the oil inlet P port and the oil outlet T port of the valve group are respectively provided with a first pressure measuring port and a fifth pressure measuring port.

[0015] Furthermore, in the conveying arm valve group, a second pressure measuring port is provided at the oil outlet of the priority flow valve, a third pressure measuring port is provided at the oil inlet of the conveying arm fan motor, and a fourth pressure measuring port is provided at the oil return port of the conveying arm fan motor.

[0016] A conveying arm hydraulic control system comprises an engine, a transfer case, a metering pump and a conveying arm valve group as described above, wherein the engine is connected to the transfer case, and the transfer case is connected to the metering pump; the oil inlet of the metering pump is connected to the oil suction filter, and the oil outlet of the metering pump is connected to the oil inlet P port of the valve group.

[0017] The advantages and effects of the present invention are:

[0018] The conveying arm valve group and the conveying arm hydraulic control system provided by the present invention utilize a proportional solenoid valve combination for an actuator with precise control, thereby improving controllability and being energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram showing the hydraulic control principle of the conveying arm valve group provided by the present invention is shown;

[0020] Figure 2 A schematic structural diagram of the conveying arm provided by the present invention is shown.

[0021] Explanation of the accompanying drawings: first two-position two-way solenoid valve 1-1, second two-position two-way solenoid valve 1-2, first overflow valve 2, priority flow valve 3, second overflow valve 4-1, third overflow valve 4-2, two-position four-way hydraulic control valve 5, first two-position three-way solenoid valve 6-1, second two-position three-way solenoid valve 6-2, first three-way four-way proportional solenoid valve 7-1, second three-way four-way proportional solenoid valve 7-2, third three-way four-way proportional solenoid valve 8, balancing valve 9, engine 10, transfer case 11, metering pump 12, oil suction filter 13, oil tank 14, conveying arm valve group 15, first conveying arm motor 16-1, second conveying arm motor 16-2, conveying arm fan motor 17, conveying arm fan rotation motor 18, tail unloading cylinder 19, first conveying arm lifting cylinder 20-1, second conveying arm lifting cylinder 20-2. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the implementation of the present invention clearer, the technical solutions in the embodiments of the present invention are described in more detail below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, rather than all the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be understood as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings:

[0023] In the description of the present invention, it should be understood that, unless otherwise specified, the meaning of "multiple" is two or more; the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention. In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0024] Example:

[0025] Figure 1 The hydraulic control principle diagram of the conveying arm valve group provided by the present invention is shown. The conveying arm valve group 15 includes a first two-position two-way solenoid valve 1-1 and a second two-position two-way solenoid valve 1-2. The oil inlet P port of the conveying arm valve group 15 is connected to the oil inlet of the first two-position two-way solenoid valve 1-1, the oil inlet of the second two-position two-way solenoid valve 1-2 and the oil inlet of the conveying arm fan motor 17, the oil outlet of the first two-position two-way solenoid valve 1-1 is connected to the return oil T port of the conveying arm valve group 15, the oil outlet of the second two-position two-way solenoid valve 1-2 is connected to the oil inlet of the first conveying arm motor 16-1 and the second conveying arm motor 16-2, the return oil port of the conveying arm fan motor 17 is connected to the oil inlet of the first conveying arm motor 16-1 and the second conveying arm motor 16-2, and the return oil port of the first conveying arm motor 16-1 and the second conveying arm motor 16-2 is connected to the return oil T port of the conveying arm valve group 15. In this embodiment, as Figure 1As shown, the oil inlet P port of the conveying arm valve group 15 is used to connect to the output port of the pump, the oil return T port of the conveying arm valve group 15 is used to connect to the hydraulic oil tank, the A1 and B1 ports of the conveying arm valve group 15 are respectively connected to the oil inlet and oil return port of the conveying arm fan motor 17, the A2 and B2 ports of the conveying arm valve group 15 are respectively connected to the oil inlet and oil return port of the conveying arm fan rotation motor 18, the A3 and B3 ports of the conveying arm valve group 15 are respectively connected to the large chamber and small chamber of the conveying arm tail unloading cylinder 19, and the A4 and B4 ports of the conveying arm valve group 15 are respectively connected to the conveying arm lifting cylinder (for example For example, the large chamber and small chamber of the first conveying arm lifting cylinder 20-1 and the second conveying arm lifting cylinder 20-2 are connected in parallel, and the A5 and B5 ports of the conveying arm valve group 15 are respectively connected to the oil inlet and oil return port of the first conveying arm motor 16-1 and the second conveying arm motor 16-2, and the M1, M2, M3, M4, and M5 ports of the conveying arm valve group 15 are respectively the oil inlet P port of the conveying arm valve group, the oil outlet of the priority flow valve 3, the oil inlet of the conveying arm fan motor 17, the oil return port of the conveying arm fan motor 17, and the pressure measuring port of the oil outlet T port of the conveying arm valve group 15.

[0026] When the conveying arm valve assembly 15 does not perform any action, the first two-position two-way solenoid valve 1-1 is in a de-energized state. The hydraulic oil at the oil inlet P of the conveying arm valve assembly 15 passes through the first two-position two-way solenoid valve 1-1, then flows through the oil outlet T of the conveying arm valve assembly 15 and returns to the oil tank (14). At this time, the first two-position two-way solenoid valve 1-1 is bypassed, and the conveying arm hydraulic control system basically does not consume energy, which is energy-saving and environmentally friendly.

[0027] When the first two-position two-way solenoid valve 1-1 of the conveying arm valve assembly 15 is energized and the second two-position two-way solenoid valve 1-2 is de-energized, the first conveying arm motor 16-1 and the second conveying arm motor 16-2 rotate forward simultaneously, and the conveying arm fan motor 17 does not rotate. When the first two-position two-way solenoid valve 1-1 and the second two-position two-way solenoid valve 1-2 are energized simultaneously, the conveying arm fan motor 17, the first conveying arm motor 16-1, and the second conveying arm motor 16-2 rotate forward simultaneously.

[0028] Specifically, the conveying arm valve assembly 15 further includes a first 2-position 3-way solenoid valve 6-1 and a 2-position 4-way hydraulic control valve 5. The oil inlet of the first 2-position 3-way solenoid valve 6-1 is connected to the oil outlet of the second 2-position 2-way solenoid valve 1-2, and the oil outlet of the first 2-position 3-way solenoid valve 6-1 is connected to the oil return ports of the first conveying arm motor 16-1 and the second conveying arm motor 16-2 via the 2-position 4-way hydraulic control valve 5.

[0029] When the first two-position two-way solenoid valve 1-1 and the first two-position three-way solenoid valve 6-1 of the conveying arm valve group 15 are energized at the same time, the high-pressure oil pushes the two-position four-way hydraulic control valve to shift position 5 through the first two-position three-way solenoid valve 6-1, and the first conveying arm motor 16-1 and the second conveying arm motor 16-2 reverse at the same time.

[0030] In addition, the conveying arm valve assembly 15 also includes a second two-position three-way solenoid valve 6-2. The oil inlet P port of the conveying arm valve assembly 15 is connected to the oil inlet of the second two-position three-way solenoid valve 6-2, and the first oil outlet of the second two-position three-way solenoid valve 6-2 is connected to the oil return T port of the conveying arm valve assembly 15. The second oil outlet of the second two-position three-way solenoid valve 6-2 is connected to the oil inlet of the first three-position four-way proportional solenoid valve 7-1, the oil outlet of the first three-position four-way proportional solenoid valve 7-1 is connected to the oil inlet of the second three-position four-way proportional solenoid valve 7-2, the oil outlet of the second three-position four-way proportional solenoid valve 7-2 is connected to the oil inlet of the third three-position four-way proportional solenoid valve 7-3, and the oil outlet of the third three-position four-way proportional solenoid valve 7-3 is connected to the oil return T port of the conveying arm valve assembly 15. The first three-position four-way proportional solenoid valve 7-1, the second three-position four-way proportional solenoid valve 7-2 and the third three-position four-way proportional solenoid valve 7-3 can change the current passing through the electromagnetic coil according to actual needs, thereby achieving the control of the proportional valve spool to be adjusted to any position, and to a certain extent, can accurately control the movement speed of the motor and the cylinder, thereby improving the operating performance.

[0031] The first, three-position, four-way proportional solenoid valve 7-1 is connected to the conveyor arm fan motor 18. When the second, two-position, three-way solenoid valve 6-2 of the conveyor arm valve assembly 15 and the first, three-position, four-way proportional solenoid valve 7-1 are energized simultaneously, the conveyor arm fan motor 18 operates. When the first, three-position, four-way proportional solenoid valve 7-1 is in the left position, the conveyor arm fan motor 18 rotates forward; when the first, three-position, four-way proportional solenoid valve 7-1 is in the right position, the conveyor arm fan motor 18 rotates reversely.

[0032] The second, three-position, four-way proportional solenoid valve 7-2 is connected to the conveyor arm's tail discharge cylinder 19. When the second, two-position, three-way solenoid valve 6-2 and the second, three-position, four-way proportional solenoid valve 7-2 of the conveyor arm valve assembly 15 are energized simultaneously, the tail discharge cylinder 19 operates. When the second, three-position, four-way proportional solenoid valve 7-2 is in the left position, the tail discharge cylinder 19 opens; when the second, three-position, four-way proportional solenoid valve 7-2 is in the right position, the tail discharge cylinder 19 closes.

[0033] The third, three-position, four-way proportional solenoid valve 7-3 is connected to the conveyor arm lifting cylinder (the first conveyor arm lifting cylinder 20-1 and the second conveyor arm lifting cylinder 20-2 in parallel). When the second, two-position, three-way proportional solenoid valve 6-2 and the third, three-position, four-way proportional solenoid valve 8 of the conveyor arm valve group 15 are energized at the same time, the first conveyor arm lifting cylinder 20-1 and the second conveyor arm lifting cylinder 20-2 operate. Specifically, when the third, three-position, four-way proportional solenoid valve 8 is in the left position, the first conveyor arm lifting cylinder 20-1 and the second conveyor arm lifting cylinder 20-2 descend; when the third, three-position, four-way proportional solenoid valve 8 is in the right position, the first conveyor arm lifting cylinder 20-1 and the second conveyor arm lifting cylinder 20-2 ascend. Furthermore, a balancing valve 9 is provided between the third, three-position, four-way proportional solenoid valve 8 and the first conveyor arm lifting cylinder 20-1 and the second conveyor arm lifting cylinder 20-2 in parallel to ensure that the conveyor arm does not overspeed and maintains its state when descending.

[0034] Furthermore, a priority flow valve 3 is provided between the oil inlet P port of the conveying arm valve assembly 15 and the oil inlet port of the second two-position three-way solenoid valve 6-2. When the second two-position three-way solenoid valve 6-2 of the conveying arm valve assembly 15 loses power, the hydraulic oil flowing through the priority port of the priority flow valve 3 returns to the main oil circuit. When the second two-position three-way solenoid valve 6-2 is energized, the hydraulic oil in the priority port flows to the first three-position four-way proportional solenoid valve, the second three-position four-way proportional solenoid valve 7-2, and the third three-position four-way proportional solenoid valve 8.

[0035] Specifically, a first relief valve 2 is installed between the oil inlet P port of the conveying arm valve assembly 15 and the oil return T port of the conveying arm valve assembly 15. A second relief valve 4-1 is installed between the first oil outlet of the second two-position three-way solenoid valve 6-2 and the oil return T port of the conveying arm valve assembly 15. A third relief valve 4-2 is installed between the oil inlet and oil outlet of the second two-position two-way solenoid valve 1-2. The first relief valve 2, the second relief valve 4-1, and the third relief valve 4-2 all serve to protect the hydraulic system. To ensure the functioning of the second relief valve 4-1 and the third relief valve 4-2, the relief pressure of the second relief valve 4-1 and the third relief valve 4-2 is 1.5 MPa lower than the relief pressure of the first relief valve 2.

[0036] The oil inlet P port of the conveying arm valve group 15 is provided with a first pressure measuring port M1, the oil outlet port of the priority flow valve 3 is provided with a second pressure measuring port M2, the oil inlet port of the conveying arm fan motor 17 is provided with a third pressure measuring port M3, the oil return port of the conveying arm fan motor 17 is provided with a fourth pressure measuring port M4, and the oil outlet T port of the conveying arm valve group 15 is provided with a fifth pressure measuring port M5.

[0037] like Figure 2The conveying arm hydraulic control system of the conveying arm shown includes an engine 10, a transfer case 11, a metering pump 12, and the aforementioned conveying arm valve assembly 15. One end of the metering pump 12 is mechanically connected to the transfer case 11, and the transfer case 11 is mechanically connected to the engine 10 via a spline. The oil inlet of the metering pump 12 is connected to the oil tank 14 via a hydraulic hose through an oil suction filter 13, and the oil outlet of the metering pump 12 is connected to the oil inlet P port of the conveying arm valve assembly 15. The engine 10 provides mechanical power for the conveying arm hydraulic control system, the transfer case 11 increases the pump inlet speed by changing the transmission ratio through the gears inside the case, the metering pump 12 provides pressurized oil for the conveying arm hydraulic control system, and the oil suction filter 13 filters impurities in the hydraulic oil.

[0038] In this embodiment, the conveying arm hydraulic control system also includes a conveying arm valve group 15, a first conveying arm motor 16-1, a second conveying arm motor 16-2, a conveying arm fan motor 17, a conveying arm fan rotation motor 18, a tail unloading cylinder 19, a first conveying arm lifting cylinder 20-1 and a second conveying arm lifting cylinder 20-2. The output port of the metering pump 12 is connected to the oil inlet P port of the conveying arm valve group, the oil return T port of the conveying arm valve group 15 is connected to the oil tank 14, the oil inlet and oil return port of the conveying arm fan motor 17 are respectively connected to the A1 and B1 ports of the conveying arm valve group 15, the oil inlet and oil return port of the conveying arm fan rotation motor 18 are respectively connected to the A2 and B2 ports of the conveying arm valve group 15, the large chamber and small chamber of the conveying arm tail unloading cylinder 19 are respectively connected to the A3 and B3 ports of the conveying arm valve group 15, the large chamber and small chamber of the parallel first conveying arm lifting cylinder 20-1 and the second conveying arm lifting cylinder 20-2 are respectively connected to the A4 and B4 ports of the conveying arm valve group 15, the oil inlet and oil return port of the parallel first conveying arm motor 16-1 and the second conveying arm motor 16-2 are respectively connected to the A5 and B5 ports of the conveying arm valve group 15. The M1, M2, M3, M4, and M5 ports of the conveying arm valve group 15 are respectively the oil inlet P port of the conveying arm valve group, the oil outlet of the priority flow valve 3, the oil inlet of the conveying arm fan motor 17, the oil return port of the conveying arm fan motor 17, and the pressure measuring port of the oil outlet T port of the conveying arm valve group 15.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of implementation of the present invention. Any equivalent changes and modifications made within the scope of protection of the present invention should be considered to fall within the scope of protection of the present invention.

Claims

1. A conveying arm valve group, characterized in that: The valve group includes a first two-position two-way solenoid valve and a second two-position two-way solenoid valve, an oil inlet P port of the valve group is connected to the oil inlet of the first two-position two-way solenoid valve, the oil inlet of the second two-position two-way solenoid valve and the oil inlet of the conveying arm fan motor, an oil outlet of the first two-position two-way solenoid valve is connected to the oil return T port of the valve group, an oil outlet of the second two-position two-way solenoid valve is connected to the oil inlet of the first conveying arm motor and the second conveying arm motor, an oil return port of the conveying arm fan motor is connected to the oil inlet of the first conveying arm motor and the second conveying arm motor, and an oil return port of the first conveying arm motor and the second conveying arm motor is connected to the oil return T port of the valve group; The valve group also includes a first two-position three-way solenoid valve and a two-position four-way hydraulic control valve, wherein the oil inlet of the first two-position three-way solenoid valve is connected to the oil outlet of the second two-position two-way solenoid valve, and the oil outlet of the first two-position three-way solenoid valve is connected via the control port of the two-position four-way hydraulic control valve; When the first two-position two-way solenoid valve is energized and the second two-position two-way solenoid valve is de-energized, the first conveying arm motor and the second conveying arm motor rotate forward at the same time, and the conveying arm fan motor does not rotate; when the first two-position two-way solenoid valve and the second two-position two-way solenoid valve are energized at the same time, the conveying arm fan motor, the first conveying arm motor, and the second conveying arm motor rotate forward at the same time.

2. A conveying arm valve assembly according to claim 1, characterized in that: The valve group also includes a second two-position three-way solenoid valve, the oil inlet P port of the valve group is connected to the oil inlet of the second two-position three-way solenoid valve, and the first oil outlet of the second two-position three-way solenoid valve is connected to the oil return T port of the valve group; the second oil outlet of the second two-position three-way solenoid valve is connected to the oil inlet of the first three-position four-way proportional solenoid valve, the oil outlet of the first three-position four-way proportional solenoid valve is connected to the oil inlet of the second three-position four-way proportional solenoid valve, the oil outlet of the second three-position four-way proportional solenoid valve is connected to the oil inlet of the third three-position four-way proportional solenoid valve, and the oil outlet of the third three-position four-way proportional solenoid valve is connected to the oil return T port of the valve group.

3. A conveying arm valve assembly according to claim 2, characterized in that: A priority flow valve is provided between the oil inlet P port of the valve group and the oil inlet port of the second two-position three-way solenoid valve.

4. A conveying arm valve assembly according to claim 2, characterized in that: The first three-position four-way proportional solenoid valve is connected to the conveying arm fan rotation motor, the second three-position four-way proportional solenoid valve is connected to the conveying arm tail unloading cylinder, and the third three-position four-way proportional solenoid valve is connected to the conveying arm lifting cylinder.

5. The conveying arm valve assembly according to claim 2, characterized in that: A first overflow valve is provided between the oil inlet P port of the valve group and the oil return T port of the valve group, a second overflow valve is provided between the first oil outlet of the second two-position three-way solenoid valve and the oil return T port of the valve group, and a third overflow valve is provided between the oil inlet and the oil outlet of the second two-position two-way solenoid valve.

6. The conveying arm valve assembly according to claim 5, characterized in that: The relief pressure of the second relief valve and the third relief valve is 1.5 MPa lower than that of the first relief valve.

7. The conveying arm valve assembly according to claim 1, characterized in that: The oil inlet P port and the oil outlet T port of the valve group are respectively provided with a first pressure measuring port and a fifth pressure measuring port.

8. The conveying arm valve assembly according to claim 3, characterized in that: The oil outlet of the priority flow valve is provided with a second pressure measuring port, the oil inlet of the conveying arm fan motor is provided with a third pressure measuring port, and the oil return port of the conveying arm fan motor is provided with a fourth pressure measuring port.

9. A hydraulic control system for a conveying arm, characterized in that: The system includes an engine, a transfer case, a metering pump and a conveying arm valve group as described in any one of claims 1 to 8, wherein the engine is connected to the transfer case, and the transfer case is connected to the metering pump; the oil inlet of the metering pump is connected to the oil suction filter, and the oil outlet of the metering pump is connected to the oil inlet P port of the valve group.

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