Luffing control system and control method for self-propelled aerial work platform

Abstract

The present invention discloses a boom control system and control method for a self-propelled aerial work platform. The first oil circuit of the boom control system includes, in order of connection: the A oil circuit port of the control valve, the oil inlet and oil outlet of the first hydraulically controlled one-way valve, the zero-differential dynamic balancing valve, and the large chamber of the boom cylinder. The second oil circuit of the boom control system includes, in order of connection: the B oil circuit port of the control valve, the oil inlet and oil outlet of the back-pressure sequence valve, the oil inlet of the external one-way valve, the oil inlet and oil outlet of the second hydraulically controlled one-way valve, and the small chamber of the boom cylinder. The oil outlet of the external one-way valve is connected to the oil tank. By adopting the above technical solution, the control of the falling boom action is not affected by the external load force, and the deadweight of the boom is used to achieve smooth falling control, thereby improving safety and reliability. The pressure setting value for opening the zero-differential dynamic balancing valve and the back-pressure sequence valve can be set to a lower value, thereby reducing system energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a variable amplitude control system for a self-propelled aerial work platform and a control method thereof. Background Art

[0002] Self-propelled aerial work platforms are primarily used in construction. As manned engineering vehicles, their safety is extremely important. The amplitude control system is a major component of the safety control system of self-propelled aerial work platforms and is closely related to their safety.

[0003] In the prior art, the variable amplitude control system of self-propelled aerial work platforms generally adopts a conventional standard balance valve control method. Its variable amplitude balance valve is basically an ordinary double-one-way balance valve structure. The large and small chambers of the variable amplitude cylinder are each controlled by a balance valve. In the process of executing the variable amplitude lowering action of the boom, there are the following problems: (1) The opening pressure of the balance valve is too high, resulting in a high output pressure of the working pump and the output power of the engine, and a large energy loss; (2) There is no pressure compensation in the process control of the variable amplitude lowering action, which is greatly affected by the external load force, resulting in poor smoothness and stability of the fall, and under the external load weight. When the load is too large, the change in the boom boom angle will lead to a large change in the external load force, which in turn corresponds to a large change in the force on the boom boom cylinder. Therefore, the oil pressure inside the balance valve is high and has a strong volatility, which can easily cause damage to the balance valve core and pose a major safety hazard. (3) There is no secondary redundant safety design. The balance valve that controls the large-cavity load holding function of the boom boom cylinder is only a single balance valve structure. When the balance valve core is stuck and cannot be reset, the boom boom falling action will be completely uncontrolled, posing a major safety hazard to personnel and equipment. (4) The overall structure is relatively complex. Summary of the Invention

[0004] Purpose of the invention: The present invention aims to provide a boom control system and a control method for a self-propelled aerial work platform. By coordinating the set pressure value of the zero-differential dynamic balancing valve with the set pressure value of the back-pressure sequence valve, during the boom lowering boom movement, the control of the boom is not affected by the external load force, and the boom's own weight is used to achieve smooth falling control, thereby improving safety and reliability. The pressure setting value for opening the zero-differential dynamic balancing valve and the back-pressure sequence valve can be set lower to reduce system energy consumption. The design of the zero-differential dynamic balancing valve and the hydraulically controlled one-way valve realizes secondary safety redundancy. In addition, the overall structure of the system is relatively simple.

[0005] Technical solution: The present invention provides a variable amplitude control system for a self-propelled aerial work platform, comprising: a control valve, a hydraulically controlled gravity descent control valve group, a variable amplitude oil cylinder and an oil tank, wherein: the hydraulically controlled gravity descent control valve group comprises a zero differential dynamic balancing valve, a first hydraulically controlled one-way valve, a second hydraulically controlled one-way valve, a back pressure sequence valve and an external one-way valve; the P oil port of the control valve is connected to the oil tank, and when the control valve is switched to the A-way function, the oil enters the A oil port from the P oil port; when the control valve is switched to the B-way function, the oil enters the B oil port from the P oil port; the first oil circuit of the variable amplitude control system comprises, in order of connection: the A oil port of the control valve, the oil inlet and oil outlet of the first hydraulically controlled one-way valve, the zero differential dynamic balancing valve and the large chamber of the variable amplitude oil cylinder; the zero differential dynamic balancing valve comprises an internal one-way valve and a balancing valve, and the internal one-way valve The oil inlet is connected to the oil outlet of the first hydraulically controlled one-way valve, the oil outlet of the internal one-way valve is connected to the large chamber of the boom cylinder, the oil inlet of the balancing valve is connected to the large chamber of the boom cylinder, and the oil outlet of the balancing valve is connected to the oil outlet of the first hydraulically controlled one-way valve; the second oil circuit of the boom control system includes, in order of connection: the B oil circuit port of the control valve, the oil inlet and oil outlet of the back pressure sequence valve, the oil inlet of the external one-way valve, the oil inlet and oil outlet of the second hydraulically controlled one-way valve, and the small chamber of the boom cylinder; the oil outlet of the external one-way valve is connected to the oil tank; a control oil circuit is provided between the first hydraulically controlled one-way valve and the B oil circuit port of the control valve, a control oil circuit is provided between the zero differential balancing valve and the B oil circuit port of the control valve, and a control oil circuit is provided between the second hydraulically controlled one-way valve and the oil outlet of the first hydraulically controlled one-way valve.

[0006] Specifically, the hydraulically controlled gravity descent control valve group further includes a thermal relief valve, which is arranged between the oil inlet of the balancing valve and the oil outlet of the second hydraulically controlled one-way valve.

[0007] Specifically, the first pressure setting value for opening the balancing valve is smaller than the second pressure setting value for opening the back pressure sequence valve.

[0008] Specifically, the difference between the first pressure setting value and the second pressure setting value is constant.

[0009] Specifically, the control valve is a turntable proportional control valve.

[0010] Specifically, the hydraulically controlled gravity descent control valve group further includes a balancing damper, which is arranged between the oil port A and the oil port B of the control valve.

[0011] The present invention also provides a control method for a variable amplitude control system, which is applied to any variable amplitude control system provided by the present invention, including: the control process of lifting the variable amplitude action includes: the control valve is switched to the A-way function, the oil enters the A-way port from the P oil port, passes through the first hydraulically controlled one-way valve and the internal one-way valve, and enters the large chamber of the variable amplitude cylinder, the oil also flows from the oil outlet of the first hydraulically controlled one-way valve through the control oil circuit to the second hydraulically controlled one-way valve, and controls the reverse flow of the second hydraulically controlled one-way valve; the oil in the small chamber of the variable amplitude cylinder passes through the second hydraulically controlled one-way valve and the external one-way valve. valve, into the oil tank; the control process of the falling and booming action includes: the control valve is switched to the B-way function, the oil enters the B-way port from the P-way port, passes through the back pressure sequence valve and the second hydraulically controlled one-way valve, and enters the small chamber of the boom cylinder. The oil also flows from the B-way port to the first hydraulically controlled one-way valve and the balancing valve through the control oil circuit to control the reverse flow of the first hydraulically controlled one-way valve and the opening of the balancing valve. The oil also flows from the outlet of the back pressure sequence valve through the external one-way valve to the oil tank; the oil in the large chamber of the boom cylinder passes through the balancing valve, the first hydraulically controlled one-way valve and the control valve and enters the oil tank.

[0012] Beneficial effects: Compared with the existing technology, the present invention has the following significant advantages: the control of the falling and boom-changing action is not affected by the external load force, and the boom's own weight is used to achieve smooth falling control, thereby improving safety and reliability. The pressure setting value for opening the zero-differential dynamic balancing valve and the back-pressure sequence valve can be set lower, thereby reducing system energy consumption. The design of the zero-differential dynamic balancing valve and the hydraulically controlled one-way valve realizes secondary safety redundancy, and the overall system structure is relatively simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic structural diagram of the luffing control system provided by the present invention;

[0014] 1-control valve; 2-hydraulic gravity descent control valve group; 201-zero differential dynamic balancing valve; 202-first hydraulically controlled one-way valve; 203-balancing damper; 204-thermal overflow valve; 205-second hydraulically controlled one-way valve; 206-back pressure sequence valve; 207-external one-way valve; 3-variable oil cylinder. DETAILED DESCRIPTION

[0015] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0016] See Figure 1 , which is a structural diagram of the luffing control system provided by the present invention, wherein the solid line represents the main oil circuit of the luffing control system, and the dotted line represents the control oil circuit of the luffing control system.

[0017] The present invention provides a luffing control system for a self-propelled aerial work platform, comprising: a control valve 1, a hydraulically controlled gravity descent control valve group 2, a luffing oil cylinder 3 and an oil tank, wherein: the hydraulically controlled gravity descent control valve group 2 comprises a zero-differential dynamic balancing valve 201, a first hydraulically controlled one-way valve 202, a second hydraulically controlled one-way valve 205, a back pressure sequence valve 206 and an external one-way valve 207; the P oil port of the control valve 1 is connected to the oil tank, and when the control valve 1 is switched to the A oil port, the oil tank is opened. When the function is switched to the B function, the oil flows from the P oil port to the A oil port; when the control valve 1 is switched to the B function, the oil flows from the P oil port to the B oil port; the first oil circuit of the variable amplitude control system includes, in order of connection: the A oil port of the control valve 1, the oil inlet and oil outlet of the first hydraulically controlled one-way valve 202, the zero differential dynamic balancing valve 201 and the large chamber of the variable amplitude cylinder 3; the zero differential dynamic balancing valve 201 includes an internal one-way valve and a balancing valve, the oil inlet of the internal one-way valve The oil outlet of the first hydraulically controlled one-way valve 202 is connected, the oil outlet of the internal one-way valve is connected to the large chamber of the luffing cylinder, the oil inlet of the balancing valve is connected to the large chamber of the luffing cylinder 3, and the oil outlet of the balancing valve is connected to the oil outlet of the first hydraulically controlled one-way valve 202; the second oil circuit of the luffing control system includes, in order of connection: the B oil circuit port of the control valve 1, the oil inlet and oil outlet of the back pressure sequence valve 206, the oil inlet of the external one-way valve 207, The oil inlet and oil outlet of the second hydraulically controlled one-way valve 205, and the small chamber of the variable amplitude cylinder 3; the oil outlet of the external one-way valve 207 is connected to the oil tank; a control oil circuit is set between the first hydraulically controlled one-way valve 202 and the B oil circuit port of the control valve 1, a control oil circuit is set between the zero-differential dynamic balancing valve 201 and the B oil circuit port of the control valve, and a control oil circuit is set between the second hydraulically controlled one-way valve 205 and the oil outlet of the first hydraulically controlled one-way valve 202.

[0018] The present invention also provides a control method for a variable amplitude control system, which is applied to the variable amplitude control system provided by the present invention, including: the control process of raising the variable amplitude action (extending the piston rod of the variable amplitude oil cylinder) includes: the control valve 1 is switched to the A-way function, the oil enters the A-way port from the P-way port, passes through the first hydraulically controlled one-way valve 202 and the internal one-way valve, and enters the large chamber of the variable amplitude oil cylinder 3; the oil also flows from the oil outlet of the first hydraulically controlled one-way valve 202 to the second hydraulically controlled one-way valve 205 through the control oil circuit, and controls the reverse flow of the second hydraulically controlled one-way valve 205; the oil in the small chamber of the variable amplitude oil cylinder 3 passes through the second hydraulically controlled one-way valve 205 and the external one-way valve 207, and enters Oil tank; the control process of the falling and amplitude changing action (the piston rod of the amplitude changing cylinder retracts) includes: the control valve 1 switches to the B-way function, the oil enters the B-way port from the P-way port, passes through the back pressure sequence valve 206 and the second hydraulically controlled one-way valve 205, and enters the small chamber of the amplitude changing cylinder 3. The oil also flows from the B-way port to the first hydraulically controlled one-way valve 202 and the balancing valve through the control oil circuit to control the reverse flow of the first hydraulically controlled one-way valve 202 and the opening of the balancing valve. The oil also flows from the outlet of the back pressure sequence valve 206 through the external one-way valve 207 to the oil tank; the oil in the large chamber of the amplitude changing cylinder 3 passes through the balancing valve, the first hydraulically controlled one-way valve 202 and the control valve 1 and enters the oil tank.

[0019] In a specific implementation, under normal working conditions, the first hydraulically controlled one-way valve 202 and the second hydraulically controlled one-way valve 205 can only allow oil to flow in one direction from the oil inlet to the oil outlet. However, when they are hydraulically controlled by the oil in the control oil circuit, that is, when the control oil circuit has a set control pressure input, the piston push rod moves under the action of the pressure oil, and the push rod pushes open the one-way valve, connecting the oil inlet and outlet, so that the oil can flow from the oil outlet to the oil inlet. During the control process of the lifting and amplitude changing action, the oil flows from the oil outlet of the first hydraulically controlled one-way valve 202 to the second hydraulically controlled one-way valve 205 through the control oil circuit. The control pressure provided by the oil to the second hydraulically controlled one-way valve 205 is higher than its set pressure, which can control the oil to flow from the oil outlet of the second hydraulically controlled one-way valve 205 to the oil inlet; during the control process of the falling and amplitude changing action, the oil flows from the B oil circuit port to the first hydraulically controlled one-way valve 202 through the control oil circuit. The control pressure provided by the oil to the first hydraulically controlled one-way valve 202 is higher than its set pressure, which can control the oil to flow from the oil outlet of the first hydraulically controlled one-way valve 202 to the oil inlet.

[0020] In practice, conventional internally controlled balancing valves are internally provided with a control oil circuit. During the control process of the falling and luffing action, if the external load force is large, the oil pressure output from the large chamber of the luffing cylinder will be high. The high-pressure oil flows through the control oil circuit of the internally controlled balancing valve, affecting the control and valve opening of the internally controlled balancing valve, and thus affecting the falling speed and stability of the falling and luffing action. In addition, during the luffing control and external load holding process, the luffing control system needs to provide an additional high control pressure to hydraulically control the internally controlled balancing valve, resulting in high output pressure of the working pump and output power of the engine, large energy loss, and easy overheating of the system. The zero-differential dynamic balancing valve 201 is different from the conventional internally controlled balancing valve. The balancing valve has no internal control oil circuit. Therefore, during the falling and luffing control and external load holding process, when the oil in the large chamber of the luffing cylinder flows to the balancing valve, its pressure will not affect the control of the balancing valve. In other words, the falling and luffing control is independent of the external load force and will not affect the falling speed and stability of the falling and luffing action.

[0021] In a specific implementation, the zero-differential dynamic balancing valve 201 may be set with a first pressure setting value for opening the balancing valve, and the back-pressure sequence valve 206 may also be set with a second pressure setting value for opening.

[0022] In the embodiment of the present invention, the first pressure setting value for opening the balancing valve is smaller than the second pressure setting value for opening the back pressure sequence valve 206 .

[0023] In specific implementations, during the control of the falling and luffing motion, oil also flows from oil channel B through the control oil channel to the balancing valve, which is opened by the control pressure provided by the oil. At this time, the falling and luffing pressure is only related to the second pressure setting of the backpressure sequence valve 206 and the opening of the control valve. Because the second pressure setting is greater than the first pressure setting, when the oil pressure meets the second pressure setting for opening the backpressure sequence valve 206, the balancing valve is controlled to open, and the oil in the large chamber of the luffing cylinder can flow from the balancing valve to the first hydraulically controlled check valve 202. The first pressure setting can be much lower than that of an internally controlled balancing valve. To reliably ensure the external load holding function, an internally controlled balancing valve requires a higher pressure setting, generally between 280 and 350 bar. To ensure a smooth falling motion, the opening ratio is generally set to 2:1. The pressure required by the system to open the large chamber balancing valve is approximately 140 to 175 bar, which results in significant energy consumption. However, the first pressure setting value can be set very low, and similarly, the second pressure setting value can also be set very low. By using the deadweight of the boom to control the output of oil in the large chamber of the boom cylinder, a smooth descent of the boom independent of the external load can be achieved. For example, the first pressure setting value is 43 bar and the second pressure setting value is 50 bar, which can control the falling boom action.

[0024] In an embodiment of the present invention, the difference between the first pressure setting value and the second pressure setting value is constant.

[0025] In a specific implementation, during the boom lowering and luffing operation, the boom's lowering speed is only related to the difference in pressure settings between the back pressure sequence valve 206 and the zero differential balancing valve 201, and the opening of the zero differential balancing valve 201. During the process of outputting oil from the control valve's B oil port, the pressure of the output oil continues to increase. When the control pressure for opening the zero differential balancing valve 201 is reached, the opening of the zero differential balancing valve 201 continues to increase, and the flow rate and flow of the oil increase. When the difference between the first pressure setting value and the second pressure setting value remains constant, even if the pressure of the output oil from the B oil port continues to increase, some of the oil can flow back to the oil tank from the external one-way valve 207, reducing the pressure of the oil flowing to the small chamber of the luffing cylinder. As a result, the pressure of the oil output from the large chamber of the luffing cylinder will reach a constant state. At this time, the opening of the zero differential balancing valve 201 remains unchanged, achieving smoothness and speed stability of the boom's lowering and luffing operation.

[0026] In specific implementation, during the process of external load holding, the variable amplitude cylinder will jointly realize the load holding function by the zero-differential dynamic balancing valve 201 and the first hydraulically controlled one-way valve 202. If there is a problem in the cleanliness control process of the hydraulic component, it will cause the balancing valve core to be stuck and unable to reset. At this time, the first hydraulically controlled one-way valve 202 will continue to perform the load holding function. The dual redundant load holding will greatly improve the safety of the entire vehicle operation.

[0027] In an embodiment of the present invention, the hydraulically controlled gravity descent control valve group 2 also includes a thermal overflow valve 204, which is arranged between the oil inlet of the balancing valve and the oil outlet of the second hydraulically controlled one-way valve 205, and plays a thermal overflow protection function to prevent high-temperature thermal radiation from causing safety risks such as explosion of the variable-length oil cylinder.

[0028] In an embodiment of the present invention, the control valve is a turntable proportional control valve.

[0029] In the specific implementation, when the turntable proportional control valve Y2a end is energized, the turntable proportional valve switches to the left position function, and the hydraulic oil source will reach the A road from the P road. When the turntable proportional control valve Y2b end is energized, the turntable proportional valve switches to the right position function, and the hydraulic oil source will reach the B road from the P road.

[0030] In the embodiment of the present invention, the hydraulically controlled gravity descent control valve group 2 further includes a balancing damper 203 , which is disposed between the oil port A and the oil port B of the control valve.

[0031] In specific implementation, the balanced damping 203 can be used to adapt to a variety of rotary proportional valve groups with different functions. Figure 1The neutral position function of the proportional control valve in the middle position is Y-function. If the valve group with the neutral position function is O-function, the balancing damper 203 here must be configured to balance the pressure in oil lines A and B on both sides of the cylinder, ensuring the reliable closure of the zero-differential dynamic balancing valve 201 and the first hydraulically controlled check valve 202. If the valve group with O-function is matched, without the balancing damper 203 here, when the cylinder drops and luffs, high pressure will reach the oil inlet of the external check valve 207 through line B. After stopping, the high pressure will be blocked by the O-function valve group. At this time, the zero-differential dynamic balancing valve 201 and the first hydraulically controlled check valve 202 cannot be reliably closed and will be in a floating open state. The hydraulic oil in the large chamber of the luffing cylinder will flow through the zero-differential dynamic balancing valve 201 and the first hydraulically controlled check valve 202 to the O-function spool of the proportional control valve. Since the control valve is a spool valve mechanism, it has a large internal leakage. At this time, the luffing cylinder will automatically drop, and the effective load locking function of the hydraulically controlled gravity descent control valve group 2 will be ineffective.

Claims

1. A variable amplitude control system for a self-propelled aerial work platform, characterized in that: include: Control valve, hydraulically controlled gravity descent control valve group, luffing cylinder and oil tank, including: The hydraulically controlled gravity descent control valve group includes a zero differential dynamic balancing valve, a first hydraulically controlled one-way valve, a second hydraulically controlled one-way valve, a back pressure sequence valve and an external one-way valve; The P oil port of the control valve is connected to the oil tank. When the control valve is switched to the A function, the oil flows from the P oil port to the A oil port; when the control valve is switched to the B function, the oil flows from the P oil port to the B oil port. The first oil circuit of the luffing control system includes, in order of connection: an oil circuit port A of the control valve, an oil inlet and an oil outlet of a first hydraulically controlled one-way valve, a zero-differential dynamic balancing valve, and a large chamber of the luffing cylinder; the zero-differential dynamic balancing valve includes an internal one-way valve and a balancing valve, the oil inlet of the internal one-way valve is connected to the oil outlet of the first hydraulically controlled one-way valve, the oil outlet of the internal one-way valve is connected to the large chamber of the luffing cylinder, the oil inlet of the balancing valve is connected to the large chamber of the luffing cylinder, and the oil outlet of the balancing valve is connected to the oil outlet of the first hydraulically controlled one-way valve; The second oil circuit of the luffing control system includes, in order of connection: the B oil circuit port of the control valve, the oil inlet and oil outlet of the back pressure sequence valve, the oil inlet of the external one-way valve, the oil inlet and oil outlet of the second hydraulically controlled one-way valve, and the small chamber of the luffing cylinder; the oil outlet of the external one-way valve is connected to the oil tank; A control oil circuit is provided between the first hydraulically controlled one-way valve and the B oil circuit port of the control valve, a control oil circuit is provided between the zero differential balancing valve and the B oil circuit port of the control valve, and a control oil circuit is provided between the second hydraulically controlled one-way valve and the oil outlet of the first hydraulically controlled one-way valve; the first pressure setting value for opening the balancing valve is less than the second pressure setting value for opening the back pressure sequence valve.

2. The luffing control system for a self-propelled aerial work platform according to claim 1, characterized in that: The hydraulically controlled gravity descent control valve group further includes a thermal relief valve, which is arranged between the oil inlet of the balancing valve and the oil outlet of the second hydraulically controlled one-way valve.

3. The luffing control system for a self-propelled aerial work platform according to claim 1, characterized in that: The difference between the first pressure setting and the second pressure setting is constant.

4. The luffing control system for a self-propelled aerial work platform according to claim 1, characterized in that: The control valve is a turntable proportional control valve.

5. The luffing control system for a self-propelled aerial work platform according to claim 1, characterized in that: The hydraulically controlled gravity descent control valve group further includes a balancing damper, which is arranged between the oil port A and the oil port B of the control valve.

6. A control method for a variable amplitude control system, characterized in that: The luffing control system according to any one of claims 1 to 5 comprises: The control process of the lifting and luffing action includes: the control valve switches to the A-circuit function, the oil enters the A-circuit port from the P-circuit port, passes through the first hydraulically controlled one-way valve and the internal one-way valve, and enters the large chamber of the luffing cylinder. The oil also flows from the oil outlet of the first hydraulically controlled one-way valve through the control oil circuit to the second hydraulically controlled one-way valve, controlling the reverse flow of the second hydraulically controlled one-way valve; the oil in the small chamber of the luffing cylinder passes through the second hydraulically controlled one-way valve and the external one-way valve and enters the oil tank; The control process of the falling and booming action includes: the control valve switches to the B-way function, the oil enters the B-way port from the P-way port, passes through the back pressure sequence valve and the second hydraulically controlled one-way valve, and enters the small chamber of the boom cylinder. The oil also flows from the B-way port to the first hydraulically controlled one-way valve and the balancing valve through the control oil circuit to control the reverse flow of the first hydraulically controlled one-way valve and the opening of the balancing valve. The oil also flows from the outlet of the back pressure sequence valve through the external one-way valve to the oil tank; the oil in the large chamber of the boom cylinder passes through the balancing valve, the first hydraulically controlled one-way valve and the control valve and enters the oil tank.

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