Control system of three-arm wheel excavator

Abstract

The utility model discloses a control system of a three-section arm wheel excavator, which comprises a pilot oil source valve, a movable arm crank arm action valve and a movable crank conversion valve, and the pilot oil source valve is used for controlling the on-off and switching of an oil way of the whole control system; the movable arm and crank arm action valve is communicated with an oil way of the pilot oil source valve and is used for switching the motion states of the upper movable arm and the crank arm; the movable crank change-over valve is communicated with an oil way of the pilot oil source valve and is used for switching on and off of an oil way between the movable arm and crank arm action valve and the upper movable arm as well as between the movable arm and crank arm action valve and the crank arm; when part of the pilot oil source valves are opened, oil ways between the pilot oil source valves and the movable arm and crank arm action valve are communicated, the movable arm and crank arm action valve controls the upper movable arm to ascend and descend, when all the pilot oil source valves are opened, the pilot oil source valves are communicated with oil ways between the movable arm and crank arm action valve and the movable crank change-over valve, the movable crank change-over valve switches the oil ways, and the movable crank change-over valve controls the upper movable arm to ascend and descend. The movable arm crank arm action valve controls the crank arm to swing left and right. And the coordination of the control system is improved, so that the upper movable arm and the crank arm run smoothly.

Description

Technical Field

[0001] The utility model belongs to the technical field of excavator control oil circuits, in particular to a control system for a three-section arm wheeled excavator. Background Art

[0002] An excavator, also known as an excavating machine or a backhoe, uses a bucket to dig materials above or below the bearing surface. Traditional excavator booms generally adopt a two-section structure. As the current working conditions become more and more complex, the working environment is increasingly restricted. For this reason, a three-section excavator is proposed. During the construction process, the three-section boom excavator can adjust the digging direction of the bucket and the overall forward extension length of the boom at any time according to the needs of the working conditions. Therefore, a control system for a three-section arm wheeled excavator should be designed to solve the coordination and responsiveness problems between the multiple upper booms and the crank arms. Utility Model Content

[0003] The utility model aims to provide a control system for a three-section arm wheeled excavator, so as to improve the problem of the coordination of the operation of the upper movable arm and the crank arm in the existing three-section arm.

[0004] The specific technical solutions are as follows:

[0005] A control system for a three-section arm wheeled excavator, used for controlling an upper boom and a crank arm of the excavator, comprising:

[0006] The pilot oil source valve is used to control the on / off and switching of the oil circuit of the entire control system;

[0007] A boom-crank arm actuating valve, the boom-crank arm actuating valve being in communication with the pilot oil source valve oil circuit and being used for switching the motion states of the upper boom and the crank arm; and

[0008] A movable crank conversion valve, the movable crank conversion valve is connected to the oil circuit of the pilot oil source valve, and is used to switch the oil circuit between the boom crank action valve and the upper boom and between the boom crank action valve and the crank arm;

[0009] Among them, when some of the pilot oil source valves are opened, the oil circuit between the pilot oil source valve and the boom crank action valve is connected, and the boom crank action valve controls the lifting and lowering of the upper boom; when all of the pilot oil source valves are opened, the pilot oil source valve is respectively connected with the oil circuit between the boom crank action valve and the movable crank conversion valve, the movable crank conversion valve switches the oil circuit, and the boom crank action valve controls the left and right swing of the crank arm; the pilot oil source valve is closed, and the entire control system stops.

[0010] Preferably, the pilot oil source valve includes a first solenoid valve and a second solenoid valve, the first solenoid valve controls the on-and-off of the oil circuit between the pilot oil source valve and the boom crank action valve, and the second solenoid valve controls the on-and-off of the oil circuit between the pilot oil source valve and the boom crank conversion valve.

[0011] Preferably, the boom-knuckle arm actuating valve has a valve core, and the valve core has an initial position, a first operating position, and a second operating position. When the valve core is in the initial position, the upper boom or the knuckle arm stops; when the valve core is in the first operating position, the upper boom rises or the knuckle arm swings to the left; and when the valve core is in the second operating position, the upper boom descends or the knuckle arm swings to the right.

[0012] Preferably, the boom crank action valve is provided with a first oil inlet, a second oil inlet and a third oil inlet, the first oil inlet is connected to the valve core oil circuit, and controls the valve core to change from the initial position to the first operating position, and the second oil inlet is connected to the valve core oil circuit, and controls the valve core to change from the initial position to the second operating position.

[0013] Preferably, the valve core is in the first operating position, the boom crutch arm actuating valve is connected to the dynamic crutch conversion valve through a first control oil circuit, and the valve core is in the second operating position, the boom crutch arm actuating valve is connected to the dynamic crutch conversion valve through a second control oil circuit.

[0014] Preferably, it also includes a single foot valve, one end of which is connected to the oil circuit of the first solenoid valve, and the other end is connected to the oil circuit of the boom crankshaft actuating valve, and the single foot valve is used to change the valve core position.

[0015] Preferably, the single-unit foot valve has a pedal point A and a pedal point B. When the pedal point A is pressed, the valve core is converted from the initial position to the first operating position. When the pedal point B is pressed, the valve core is converted from the initial position to the second operating position.

[0016] Preferably, the upper boom has an upper boom cylinder, the crank arm has a crank arm cylinder, the upper boom cylinder is connected to the movable crank conversion valve oil circuit, and the crank arm cylinder is connected to the movable crank conversion valve oil circuit.

[0017] Preferably, a third control oil circuit and a fourth control oil circuit are arranged between the upper boom cylinder and the dynamic crutch conversion valve, the third control oil circuit is used to control the upper boom to rise, the fourth control oil circuit is used to control the upper boom to fall, a fifth control oil circuit and a sixth control oil circuit are arranged between the crutch arm cylinder and the dynamic crutch conversion valve, the fifth control oil circuit is used to control the crutch arm to swing to the left, and the sixth control oil circuit controls the crutch arm to swing to the right.

[0018] Preferably, it also includes a load-sensitive hydraulic module for controlling the flow to balance the pressure difference, and the boom crank action valve feeds back the load pressure to the load-sensitive hydraulic module.

[0019] Compared with the existing technology, the beneficial effects of the utility model are as follows: an oil circuit is established among the pilot oil source valve, the boom crank arm actuating valve and the dynamic crank conversion valve, the operation of the upper boom and the crank arm is further controlled through the oil circuit, and the oil circuit between the upper boom and the crank arm and the boom crank arm actuating valve can be switched; the coordination between the pilot oil source valve, the boom crank arm actuating valve and the dynamic crank conversion valve is improved, and the smooth operation of the upper boom and the crank arm and simple operation are achieved together. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The utility model discloses an oil circuit flow chart of a control system of a three-section arm wheel excavator.

[0021] In the attached figure, 1-pilot oil source valve, 11-first solenoid valve, 12-second solenoid valve, 2-single foot valve, 3-boom crank action valve, 31-first control oil circuit, 32-second control oil circuit, 4-moving crank conversion valve, 5-upper boom cylinder, 51-third control oil circuit, 52-fourth control oil circuit, 6-crank arm cylinder, 61-fifth control oil circuit, 62-sixth control oil circuit, 7-load sensitive hydraulic module DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0024] It should also be understood that the terms used in the utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in the utility model specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0025] It should be further understood that the term “and / or” used in the present specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] In view of this, the utility model provides a control system for a three-section arm wheeled excavator, which is used to control the upper boom and crank arm of the excavator, such as Figure 1 As shown, it includes: a pilot oil source valve 1, a boom-crank arm actuation valve 3 and a dynamic crank conversion valve 4, the pilot oil source valve 1 is used to control the on-off and switching of the oil circuit of the entire control system; the boom-crank arm actuation valve 3 is connected to the pilot oil source valve 1 oil circuit, and is used to switch the motion state of the upper boom and the crank arm; the dynamic crank conversion valve 4 is connected to the pilot oil source valve 1 oil circuit, and is used to switch the on-off of the oil circuit between the boom-crank arm actuation valve 3 and the upper boom and between the boom-crank arm actuation valve 3 and the crank arm ; Wherein, when part of the pilot oil source valve 1 is opened, the oil circuit between the pilot oil source valve 1 and the boom crank action valve 3 is connected, and the boom crank action valve 3 controls the lifting and lowering of the upper boom; when the pilot oil source valve 1 is fully opened, the pilot oil source valve 1 is respectively connected with the oil circuit between the boom crank action valve 3 and the dynamic crank conversion valve 4, and the dynamic crank conversion valve 4 switches the oil circuit, and the boom crank action valve 3 controls the left and right swing of the crank arm; the pilot oil source valve 1 is closed, and the entire control system stops. An oil circuit is established between the pilot oil source valve 1 and the boom crank action valve 3 and the dynamic crank conversion valve 4, and the upper boom and the crank arm are further controlled and switched through the oil circuit; the coordination between the pilot oil source valve 1, the boom crank action valve 3 and the dynamic crank conversion valve 4 is improved, and the smooth operation and simple operation of the upper boom and the crank arm are achieved together.

[0027] In an optional embodiment, if Figure 1As shown, the pilot oil source valve 1 includes a first solenoid valve 11 and a second solenoid valve 12. The first solenoid valve 11 controls the on-off of the oil circuit between the pilot oil source valve 1 and the boom crank action valve 3, and the second solenoid valve 12 controls the on-off of the oil circuit between the pilot oil source valve 1 and the crank conversion valve 4. The function of the solenoid valve is to control the flow direction of the hydraulic oil, and is usually used for mechanical control and industrial valves to control the direction of the medium, so as to achieve control of the valve switch. In this embodiment, when it is necessary to control the operation of the upper boom, the first solenoid valve 11 is opened, and the oil circuit between the pilot oil source valve 1 and the boom crank action valve 3 is connected. At this time, the hydraulic oil enters the boom crank action valve 3 through the oil circuit, and the oil circuit between the boom crank action valve 3 and the upper boom controls the operation of the upper boom. The second solenoid valve 12 is in a closed state. When it is necessary to control the operation of the crank arm, the first solenoid valve 11 and the second solenoid valve 12 are both opened, and the oil circuit between the pilot oil source valve 1 and the boom crank action valve 3 and the movable crank conversion valve 4 is connected. The movable crank conversion valve 4 switches the oil circuit that controls the upper boom to the oil circuit that controls the crank arm. The operation is convenient and it is easy to quickly switch the oil circuit to achieve switching control of the upper boom and the crank arm.

[0028] In an optional embodiment, if Figure 1 As shown, the boom-crank arm action valve 3 has a valve core, and the valve core has an initial position, a first operating position, and a second operating position. When the valve core is in the initial position, the upper boom or the crank arm stops, when the valve core is in the first operating position, the upper boom rises or the crank arm swings to the left, and when the valve core is in the second operating position, the upper boom descends or the crank arm swings to the right. Separate oil circuits control the operating directions of the upper boom or the crank arm respectively, without interfering with each other, ensuring the smoothness of each action. The initial position of the valve core corresponds to A1 in the figure, the first operating position corresponds to A2 in the figure, and the second operating position corresponds to A3 in the figure.

[0029] In an optional embodiment, if Figure 1 As shown, the boom crank action valve 3 is provided with a first oil inlet, a second oil inlet and a third oil inlet, the first oil inlet is connected with the valve core oil circuit, and controls the valve core to change from the initial position to the first operating position, and the second oil inlet is connected with the valve core oil circuit, and controls the valve core to change from the initial position to the second operating position. As shown in the figure, the first oil inlet corresponds to point P1 of the boom crank action valve 3, the second oil inlet corresponds to point a of the boom crank action valve 3, and the third oil inlet corresponds to point b of the boom crank action valve 3. The boom crank action valve 3 is also provided with an A oil outlet and a B oil outlet.

[0030] Further, the valve core is in the first operating position, the boom crank action valve 3 is connected to the dynamic crank conversion valve 4 through the first control oil circuit 31, and the valve core is in the second operating position, and the boom crank action valve 3 is connected to the dynamic crank conversion valve 4 through the second control oil circuit 32. When it is necessary to control the upper boom to rise or the crank arm to swing to the left, the hydraulic oil enters the boom crank action valve 3 from point a, the valve core changes from the initial position to the first operating position, and the hydraulic oil flows from the A oil outlet into the first control oil circuit 31 between the boom crank action valve 3 and the dynamic crank conversion valve 4. When it is necessary to control the upper boom to fall or the crank arm to swing to the right, the hydraulic oil enters the boom crank action valve 3 from point b, the valve core changes from the initial position to the second operating position, and the hydraulic oil flows from the B oil outlet into the second control oil circuit 32 between the boom crank action valve 3 and the dynamic crank conversion valve 4. Separate oil circuits control the running direction of the upper boom or crank arm respectively without interfering with each other, ensuring the smoothness of each action. When the excavator is working, the lifting height of the upper boom can be quickly adjusted, and the crank arm can be operated to drive the bucket arm to move in a narrow working space while the upper boom remains at the height.

[0031] In an optional embodiment, if Figure 1 As shown, it also includes a single foot valve 2, one end of which is connected to the oil circuit of the first solenoid valve 11, and the other end is connected to the oil circuit of the boom crank action valve 3. The single foot valve 2 is used to change the valve core position. The single foot valve 2 is provided with a P oil inlet, and the hydraulic oil enters the single foot valve 2 through the P oil inlet. When the single foot valve 2 is stepped on, the hydraulic oil also enters the boom crank action valve 3 from the corresponding oil inlet, and the valve core position is switched from A1 to A2 or A3, which can realize precise control switching and is easy to operate.

[0032] Furthermore, the single-unit foot valve 2 has a pedal point A and a pedal point B. When the pedal point A is pressed, the valve core is converted from the initial position to the first operating position. When the pedal point B is pressed, the valve core is converted from the initial position to the second operating position.

[0033] In an optional embodiment, if Figure 1 As shown, the upper boom has an upper boom oil cylinder 5, the crank arm has a crank arm oil cylinder 6, the upper boom oil cylinder 5 is in oil communication with the movable crank conversion valve 4, and the crank arm oil cylinder 6 is in oil communication with the movable crank conversion valve 4. The operation states of the upper boom and the crank arm are controlled through different oil circuits, wherein when the upper boom is raised or lowered, the crank arm cannot swing left and right, and when the crank arm swings left and right, the upper boom is stationary.

[0034] Further, such as Figure 1As shown, a third control oil circuit 51 and a fourth control oil circuit 52 are provided between the upper boom oil cylinder 5 and the movable crank conversion valve 4. The third control oil circuit 51 is used to control the upper boom to rise, and the fourth control oil circuit 52 is used to control the upper boom to fall. A fifth control oil circuit 61 and a sixth control oil circuit 62 are provided between the crank arm oil cylinder 6 and the movable crank conversion valve 4. The fifth control oil circuit 61 is used to control the crank arm to swing to the left, and the sixth control oil circuit 62 controls the crank arm to swing to the right. Each action is provided with a separate oil circuit to avoid interference between oil circuits.

[0035] In an optional embodiment, if Figure 1 As shown, the control system of the three-section arm wheeled excavator also includes a load-sensitive hydraulic module 7, which is used to control the flow to balance the pressure difference. The boom-crank action valve 3 feeds back the load pressure to the load-sensitive hydraulic module 7. The load-sensitive hydraulic module 7 is a hydraulic circuit that senses the system pressure-flow demand and only provides the required flow and pressure. The load-sensitive hydraulic module 7 receives the load pressure signal and accurately controls the pilot oil source valve 1, such as its flow, to ensure that the pressure difference before and after each valve body is constant, so that the equipment moves smoothly and powerfully.

[0036] The pilot oil source valve 1 has a PV1 oil outlet and a PV2 oil outlet. The hydraulic oil flows to the boom arm action valve 3 and the single-joint foot valve 2 through the PV1 oil outlet, and the hydraulic oil flows to the dynamic arm conversion valve 4 through the PV2 oil outlet.

[0037] like Figure 1 As shown, the oil circuit process of the upper boom rising is: the first solenoid valve 11 is energized, the second solenoid valve 12 is de-energized, the PV1 oil outlet of the pilot oil source valve 1 discharges oil, and the PV2 oil outlet is free of oil, the hydraulic oil passes through the PV1 oil outlet, and enters the single-unit foot valve 2 and the first oil inlet from the corresponding oil circuit from the P oil inlet to the boom crank action valve 3. At this time, the crank conversion valve 4 is free of oil, and the oil circuit between the boom crank action valve 3 and the upper boom cylinder 5 is connected. When the single-unit foot valve 2 is stepped on to the A stepping point, the hydraulic oil flows out from the corresponding outlet of the single-unit foot valve 2, enters the boom crank action valve 3 from the second oil inlet, and the oil pressure changes the valve core position from A1 to A2. The hydraulic oil flows from the A oil outlet of the boom crank action valve 3 into the first control oil circuit 31, flows into the third control oil circuit 51 through the crank conversion valve 4, reaches the upper boom cylinder 5, and controls the upper boom to extend.

[0038] The oil circuit process of retracting the upper boom: the first solenoid valve 11 is energized, the second solenoid valve 12 is de-energized, the PV1 oil outlet of the pilot oil source valve 1 discharges oil, and the PV2 oil outlet is empty, the hydraulic oil passes through the PV1 oil outlet, and from the corresponding oil circuit, enters the single-unit foot valve 2 from the P oil inlet and the first oil inlet into the boom crank action valve 3, when the single-unit foot valve 2 is stepped on to the B stepping point, the hydraulic oil flows out from the corresponding outlet of the single-unit foot valve 2, enters the boom crank action valve 3 from the third oil inlet, the oil pressure changes the valve core position from A1 to A3, the hydraulic oil flows from the B oil outlet of the boom crank action valve 3 into the second control oil circuit 32, flows into the fourth control oil circuit 52 through the crank conversion valve 4, reaches the upper boom cylinder 5, and controls the retraction of the upper boom.

[0039] The oil circuit process of the left swing of the boom: the first solenoid valve 11 and the second solenoid valve 12 are both energized, and hydraulic oil flows out of the PV1 oil outlet and the PV2 oil outlet of the pilot oil source valve 1. Part of the hydraulic oil passes through the PV1 oil outlet and enters the single-unit foot valve 2 and the first oil inlet from the corresponding oil circuit from the P oil inlet to the boom crank action valve 3. Part of the PV2 oil outlet passes through the oil circuit to enter the dynamic crank conversion valve 4. The dynamic crank conversion valve 4 disconnects the oil circuit between the boom crank action valve 3 and the upper boom cylinder 5. , and establish an oil circuit between the boom crank action valve 3 and the crank cylinder 6. When the single-unit foot valve 2 is stepped on to the A stepping point, the hydraulic oil flows out from the corresponding outlet of the single-unit foot valve 2 and enters the boom crank action valve 3 from the second oil inlet. The oil pressure changes the valve core position from A1 to A2. The hydraulic oil flows from the A outlet of the boom crank action valve 3 into the first control oil circuit 31, flows into the fifth control oil circuit 61 through the movable crank conversion valve 4, and reaches the crank cylinder 6, controlling the crank to swing to the left.

[0040] The oil circuit process of the right swing of the boom: the first solenoid valve 11 and the second solenoid valve 12 are both energized, and hydraulic oil flows out of the PV1 oil outlet and the PV2 oil outlet of the pilot oil source valve 1. Part of the hydraulic oil passes through the PV1 oil outlet and enters the single-unit foot valve 2 and the first oil inlet from the corresponding oil circuit from the P oil inlet to the boom crank action valve 3. Part of the PV2 oil outlet passes through the oil circuit to enter the dynamic crank conversion valve 4. The dynamic crank conversion valve 4 disconnects the oil circuit between the boom crank action valve 3 and the upper boom cylinder 5. , and establish an oil circuit between the boom crank action valve 3 and the crank cylinder 6. When the single-unit foot valve 2 is stepped on to the B stepping point, the hydraulic oil flows out from the corresponding outlet of the single-unit foot valve 2 and enters the boom crank action valve 3 from the third oil inlet. The oil pressure changes the valve core position from A1 to A3. The hydraulic oil flows from the B outlet of the boom crank action valve 3 into the second control oil circuit 32, flows into the sixth control oil circuit 62 through the movable crank conversion valve 4, and reaches the crank cylinder 6, controlling the crank to swing to the right.

[0041] Among them, in all the above processes, when the load of the crank arm or the upper boom changes, the boom crank arm action valve 3 transmits the load pressure back to the load-sensitive hydraulic module 7 to accurately control the flow to ensure a constant pressure difference and smooth and powerful equipment movement.

[0042] System stopping process: the first solenoid valve 11 of the pilot oil source valve 1 is powered off, no oil passes through the entire control system, all controls are invalid, and the system stops.

[0043] The above description is only the preferred feasible embodiment of the utility model and is not intended to limit the scope of the patent application of the utility model. All equivalent changes, equivalent substitutions or modified changes within the technical spirit and principles suggested by the utility model should be included in the scope of patent protection covered by the utility model.

Claims

1. A control system for a three-section arm wheeled excavator, used to control the upper boom and crank arm of the excavator, characterized in that: include: The pilot oil source valve is used to control the on / off and switching of the oil circuit of the entire control system; A boom-crank arm actuating valve, the boom-crank arm actuating valve being in communication with the pilot oil source valve oil circuit and being used for switching the motion states of the upper boom and the crank arm; as well as A movable crank conversion valve, the movable crank conversion valve is connected to the oil circuit of the pilot oil source valve, and is used to switch the oil circuit between the boom crank action valve and the upper boom and between the boom crank action valve and the crank arm; Among them, when some of the pilot oil source valves are opened, the oil circuit between the pilot oil source valve and the boom crank action valve is connected, and the boom crank action valve controls the lifting and lowering of the upper boom; when all of the pilot oil source valves are opened, the pilot oil source valve is respectively connected with the oil circuit between the boom crank action valve and the movable crank conversion valve, the movable crank conversion valve switches the oil circuit, and the boom crank action valve controls the left and right swing of the crank arm; the pilot oil source valve is closed, and the entire control system stops.

2. The control system of the three-section arm wheel excavator according to claim 1, characterized in that: The pilot oil source valve includes a first solenoid valve and a second solenoid valve. The first solenoid valve controls the on-off of the oil circuit between the pilot oil source valve and the boom crank action valve, and the second solenoid valve controls the on-off of the oil circuit between the pilot oil source valve and the boom crank conversion valve.

3. The control system of the three-section arm wheel excavator according to claim 2, characterized in that: The boom-knuckle arm actuating valve comprises a valve core, and the valve core has an initial position, a first operating position, and a second operating position. When the valve core is in the initial position, the upper boom or the knuckle arm stops; when the valve core is in the first operating position, the upper boom rises or the knuckle arm swings to the left; and when the valve core is in the second operating position, the upper boom descends or the knuckle arm swings to the right.

4. The control system of the three-section arm wheel excavator according to claim 3, characterized in that: The boom crank action valve is provided with a first oil inlet, a second oil inlet and a third oil inlet. The first oil inlet is connected to the valve core oil circuit to control the valve core to change from the initial position to the first operating position. The second oil inlet is connected to the valve core oil circuit to control the valve core to change from the initial position to the second operating position.

5. The control system of the three-section arm wheel excavator according to claim 4, characterized in that: The valve core is in the first operating position, the boom crank arm actuating valve is connected to the crank conversion valve through a first control oil circuit, and the valve core is in the second operating position, the boom crank arm actuating valve is connected to the crank conversion valve through a second control oil circuit.

6. The control system of the three-section arm wheel excavator according to claim 3, characterized in that: It also includes a single foot valve, one end of which is connected to the oil circuit of the first solenoid valve, and the other end is connected to the oil circuit of the boom crankshaft action valve. The single foot valve is used to change the valve core position.

7. The control system of the three-section arm wheel excavator according to claim 6, characterized in that: The single-unit foot valve has an A pedal point and a B pedal point. When the A pedal point is pressed, the valve core is converted from the initial position to the first operating position. When the B pedal point is pressed, the valve core is converted from the initial position to the second operating position.

8. The control system of a three-section boom wheel excavator according to claim 1, characterized in that: The upper boom has an upper boom oil cylinder, the crank arm has a crank arm oil cylinder, the upper boom oil cylinder is communicated with the movable crank conversion valve oil circuit, and the crank arm oil cylinder is communicated with the movable crank conversion valve oil circuit.

9. The control system of a three-section boom wheel excavator according to claim 8, characterized in that: A third control oil circuit and a fourth control oil circuit are arranged between the upper boom cylinder and the dynamic crutch conversion valve, the third control oil circuit is used to control the upper boom to rise, and the fourth control oil circuit is used to control the upper boom to fall, a fifth control oil circuit and a sixth control oil circuit are arranged between the crank arm cylinder and the dynamic crutch conversion valve, the fifth control oil circuit is used to control the crank arm to swing to the left, and the sixth control oil circuit controls the crank arm to swing to the right.

10. The control system of a three-section boom wheel excavator according to any one of claims 1 to 5, characterized in that: It also includes a load-sensitive hydraulic module for controlling flow to balance the pressure difference, and the boom-knuckle action valve feeds the load pressure back to the load-sensitive hydraulic module.

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