Emergency retraction system and control method for aerial work vehicle

Abstract

The present invention discloses an emergency retraction system and control method for aerial work vehicles, which relates to the field of aerial work platforms and includes: a telescopic hydraulic cylinder, a balancing valve, an oil return pipe, and a proportional valve. The telescopic hydraulic cylinder is provided with a piston rod for lifting the load, and the piston rod divides the interior of the telescopic hydraulic cylinder into a rod chamber and a rodless chamber; the balancing valve outlet is connected to the rod chamber, the balancing valve inlet is connected to the rodless chamber, and the control port of the balancing valve is connected to an emergency oil source for controlling the balancing valve; the oil return pipe is connected to the rod chamber for receiving refluxed hydraulic oil; the proportional valve inlet is connected to the rodless chamber, and the proportional valve outlet is connected to the oil return pipe. The present invention effectively improves the safety of aerial work.

Description

Technical Field

[0001] The present invention relates to the technical field of aerial work platforms, and in particular to an emergency retraction system and a control method for an aerial work vehicle. Background Art

[0002] Aerial work platforms are specialized vehicles used to transport workers and equipment to high altitudes for installation, maintenance, and cleaning of equipment. Compared to traditional methods like scaffolding and ladders, they offer superior performance, high efficiency, and safety, making them widely used in infrastructure industries such as power, transportation, petrochemicals, communications, and landscaping. When a boom lift's boom is lowered by gravity, the oil in the rodless chamber of the boom cylinder flows through a two-position, two-way on-off valve and a reversing valve, then through a proportional valve and compensator before returning to the hydraulic tank. During use, if the two-position, two-way on-off valve and proportional valve controlling the boom's deadweight lowering become stuck, the valve core may not shift properly. Furthermore, the control wiring harness may rub against the boom structure, causing damage or breakage, and disrupting electrical signal transmission. This can prevent the oil from flowing back into the boom cylinder, preventing personnel from safely descending to the ground. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an emergency retraction system for an aerial work vehicle, which can enable personnel to safely descend from the air to the ground in the event of a proportional valve failure.

[0004] According to an embodiment of the present invention, an emergency retraction system for an aerial work vehicle comprises: a telescopic hydraulic cylinder, a balancing valve, an oil return pipe, and a proportional valve. The telescopic hydraulic cylinder is internally provided with a piston rod for lifting a load, the piston rod dividing the interior of the telescopic hydraulic cylinder into a rod chamber and a rodless chamber; the balancing valve outlet is connected to the rod chamber, the balancing valve inlet is connected to the rodless chamber, and the control port of the balancing valve is connected to an emergency oil source for controlling the balancing valve; the oil return pipe is connected to the rod chamber for receiving refluxed hydraulic oil; the proportional valve inlet is connected to the rodless chamber, and the proportional valve outlet is connected to the oil return pipe.

[0005] An emergency retraction system for aerial work platforms according to an embodiment of the present invention has at least the following beneficial effects: a controller can open a proportional valve, allowing hydraulic oil in the rodless chamber to flow into the rod chamber to control the piston rod's descent. If the proportional valve fails, the controller can also control the emergency oil source to open the balancing valve to lower the piston rod. By controlling the load descent using two control methods, if one control method fails, the other can be used to control the load descent, effectively improving the safety of aerial work.

[0006] According to some embodiments of the present invention, a switch valve is connected between the proportional valve and the rodless chamber, and the switch valve is used to open and close the oil circuit between the proportional valve and the rodless chamber.

[0007] According to some embodiments of the present invention, the switch valve is a two-position, two-way switch valve. When the switch valve is in a closed state, hydraulic oil cannot flow from the rodless chamber to the proportional valve inlet but can flow from the proportional valve inlet to the rodless chamber.

[0008] According to some embodiments of the present invention, the proportional valve inlet is connected to a one-way valve, and the one-way valve is connected to an oil supply pipe. The hydraulic oil can flow from the oil supply pipe to the switch valve through the one-way valve. The one-way valve is used to prevent the hydraulic oil from flowing back from the switch valve into the oil supply pipe.

[0009] According to some embodiments of the present invention, a throttle valve is connected between the balancing valve inlet and the rodless chamber, and the throttle valve is used to limit the flow of hydraulic oil flowing from the rodless chamber to the balancing valve inlet.

[0010] According to some embodiments of the present invention, a compensator is connected between the proportional valve outlet and the oil return pipe.

[0011] According to some embodiments of the present invention, the emergency oil source can adjust the hydraulic oil pressure provided to the control port of the balancing valve to control the opening of the balancing valve.

[0012] According to some embodiments of the present invention, the controller includes an acquisition module, a first control module, and a second control module. The acquisition module is used to obtain the movement speed of the piston rod. The first control module is used to control the opening of the proportional valve and the switch valve according to the speed obtained by the acquisition module. The second control module is used to control the start and stop of the emergency oil source according to the speed obtained by the acquisition module.

[0013] The present invention also provides a control method for an emergency retraction system of an aerial work vehicle, comprising the following steps:

[0014] S1: The controller adjusts the opening of the proportional valve to the minimum and switches the on-off valve to the on position, and then gradually increases the opening of the proportional valve;

[0015] S2: The controller detects the movement speed of the piston rod and controls the opening of the proportional valve and the pressure of the hydraulic oil output by the emergency oil source.

[0016] According to some embodiments of the present invention, in step S2, when the movement speed of the piston rod increases with the opening of the proportional valve, the opening of the proportional valve continues to increase until the movement speed of the piston rod reaches a preset value; when the opening of the proportional valve increases and the movement speed of the piston rod is 0 or remains unchanged, the controller starts the emergency oil source and gradually increases the hydraulic oil pressure flowing to the control port of the balancing valve until the movement speed of the piston rod reaches the preset value.

[0017] An emergency retraction system for an aerial work vehicle according to an embodiment of the present invention has at least the following beneficial effects:

[0018] (1) On the basis of using the proportional valve to control the lowering action, a spare emergency oil source and a balance valve are added. When a proportional valve or a switch valve fails, the balance valve can also be used to guide the hydraulic oil in the rodless chamber to control the load lowering;

[0019] (2) A throttle valve is installed at the inlet of the balancing valve to prevent the acquisition module from malfunctioning and causing the balancing valve to open too large, resulting in a too fast load drop speed;

[0020] (3) By setting a compensator, the flow of hydraulic oil through the proportional valve is proportional to the opening of the proportional valve when the load changes, so that the load can be kept decreasing at a constant speed.

[0021] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0023] Figure 1 A schematic diagram of an embodiment of the present invention.

[0024] Figure Number:

[0025] Telescopic hydraulic cylinder 100, piston rod 110, rod chamber 120, rodless chamber 130;

[0026] Balance valve 200, emergency oil source 210;

[0027] Oil return pipe 300;

[0028] Proportional valve 400;

[0029] On-off valve 500;

[0030] One-way valve 600, oil supply pipe 610;

[0031] Throttle valve 700;

[0032] Compensator 800. DETAILED DESCRIPTION

[0033] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0034] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0035] In the description of the present invention, "a plurality" refers to more than two. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of the indicated technical features, or implicitly indicating the order of the indicated technical features.

[0036] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0037] As the instruction manual Figure 1As shown, an emergency retraction system for an aerial work vehicle provided by an embodiment of the present application includes: a telescopic hydraulic cylinder 100, a balancing valve 200, an oil return pipe 300, and a proportional valve 400; a piston rod 110 for lifting the load is provided inside the telescopic hydraulic cylinder 100, and the piston rod 110 can move along the inner wall of the telescopic hydraulic cylinder 100. The piston at the end of the piston rod 110 divides the interior of the telescopic hydraulic cylinder 100 into a rod chamber 120 and a rodless chamber 130; the end of the piston rod 110 away from the piston is connected to a load such as an arm or an aerial work platform; the outlet of the balancing valve 200 is connected to the rod chamber 120 through a hydraulic pipeline, and the inlet of the balancing valve 200 is connected to the rodless chamber 130 through a hydraulic pipeline, and the control port of the balancing valve 200 is connected to an emergency oil source 210 for controlling the balancing valve 200; after the emergency oil source 210 controls the balancing valve 200 to open, the piston rod 110 is subjected to gravity The hydraulic oil in the rodless chamber 130 is squeezed, and the hydraulic oil enters the rod chamber 120 from the rodless chamber 130 through the balancing valve 200. The return oil pipe 300 is connected to the rod chamber 120 for receiving the returned hydraulic oil. Since the space in the rod chamber 120 is smaller than that in the rodless chamber 130, a part of the hydraulic oil passing through the balancing valve 200 flows to the return oil pipe 300 and then flows to the hydraulic oil tank for storing hydraulic oil. In this way, the oil in the rodless chamber 130 flows out, and the oil in the rod chamber 120 flows in, thereby realizing the retraction of the piston rod 110 and the load. Emergency oil source 210 should remain in standby mode during normal use. If proportional valve 400 malfunctions and a load such as an aerial work platform cannot be lowered, emergency oil source 210 switches from standby mode to active mode to provide hydraulic oil pressure to the control port of counterbalance valve 200. Counterbalance valve 200 can maintain a roughly constant flow of hydraulic oil through it despite changes in load. Therefore, using counterbalance valve 200 effectively ensures that piston rod 110 moves downward at a uniform speed within telescopic hydraulic cylinder 100, and the load is lowered at a uniform speed. The inlet of proportional valve 400 is connected to rodless chamber 130, and the outlet of proportional valve 400 is connected to oil return pipe 300. The specific structures of counterbalance valve 200 and proportional valve 400 are prior art and will not be described in detail. After the proportional valve 400 is opened, the piston rod 110 is acted upon by gravity, squeezing the hydraulic oil in the rodless chamber 130. The hydraulic oil then flows from the rodless chamber 130 through the proportional valve 400 into the oil return pipe 300. Since the rod chamber 120 is connected to the oil return pipe 300, a portion of the hydraulic oil will flow into the rod chamber 120, thereby retracting the piston rod 110 and the load. During descent, the proportional valve 400 is opened first to control the load descent. When the proportional valve 400 fails, the emergency oil source 210 is controlled to open the balancing valve 200 to lower the load. By using two control methods to control the load descent, when one control method fails, another method can be used to control the load descent, thereby effectively improving the safety of aerial work.

[0038] See also Figure 1As shown, it can be understood that the proportional valve 400 is connected to the rodless chamber 130 via an on-off valve 500, which is used to open and close the oil circuit between the proportional valve 400 and the rodless chamber 130. The on-off valve 500 has good sealing performance. When descent is not required, the on-off valve 500 is in a closed state, preventing the hydraulic oil in the rodless chamber 130 from passing through the proportional valve 400, allowing loads such as aerial work platforms to remain in the air without descending for high-altitude operations.

[0039] See also Figure 1 As shown, it can be understood that the on-off valve 500 is a two-position, two-way on-off valve 500. When the on-off valve 500 is closed, hydraulic oil cannot flow from the rodless chamber 130 to the inlet of the proportional valve 400, but can flow from the inlet of the proportional valve 400 to the rodless chamber 130. The on-off valve 500 has a one-way shutoff function, allowing hydraulic oil to flow through the on-off valve 500 into the rodless chamber 130, causing the piston rod 110 to drive the load toward the rod chamber 120, thereby achieving the lifting of a load such as an aerial work platform.

[0040] See also Figure 1 As shown, it can be understood that the inlet of the proportional valve 400 is connected to a one-way valve 600, and the one-way valve 600 is connected to an oil supply pipe 610. The hydraulic oil can flow from the oil supply pipe 610 to the switch valve 500 through the one-way valve 600. When the load such as the aerial work platform rises, the oil supply pipe 610 provides hydraulic oil, the hydraulic oil passes through the one-way valve 600, and then passes through the switch valve 500 in a closed state to enter the rodless chamber 130 to push the piston rod 110 to drive the load to rise. When descending, the switch valve 500 opens, and the hydraulic oil flows from the rodless chamber 130 to the inlet of the proportional valve 400. The one-way valve 600 is used to prevent the hydraulic oil from flowing back from the switch valve 500 to the oil supply pipe 610, so that the hydraulic oil can enter the rod chamber 120 and the return oil pipe 300 under the push of the gravity of the load.

[0041] See also Figure 1 As shown, it is understood that a throttle valve 700 is connected between the inlet of the counterbalance valve 200 and the rodless chamber 130. The throttle valve 700 is used to limit the flow of hydraulic oil from the rodless chamber 130 to the inlet of the counterbalance valve 200. Because the descent speed of a load such as an aerial work platform is proportional to the flow of hydraulic oil from the rodless chamber 130 to the rod chamber 120, if the module in the controller that detects the speed of the piston rod 110 fails, causing the counterbalance valve 200 to fully open, the throttle valve 700 can limit the descent speed of the load, such as the aerial work platform, to prevent safety accidents caused by excessive descent.

[0042] See also Figure 1As shown, it is understood that a compensator 800 is connected between the outlet of the proportional valve 400 and the oil return pipe 300. Due to the inherent characteristics of the balancing valve 200, the flow rate through the balancing valve 200 is independent of the load's driving force on the piston rod 110. Therefore, when loads of different weights are lowered, the flow rate through the balancing valve 200 remains roughly consistent. However, the proportional valve 400 does not have this characteristic. Therefore, the addition of the compensator 800 ensures that the hydraulic oil flow rate through the proportional valve 400 is approximately constant at the same opening, independent of load pressure fluctuations. This ensures that the flow rate through the proportional valve 400 varies proportionally with the input electrical signal, thereby better controlling the speed of the descent of loads of different weights.

[0043] See also Figure 1 As shown, it is understood that the emergency oil source 210 can adjust the hydraulic oil pressure supplied to the control port of the counterbalance valve 200 to control the opening of the counterbalance valve 200. The emergency oil source 210 can be composed of an independent power supply and an independent hydraulic pump, with the start, stop, and speed of the independent hydraulic pump controlled by a controller. By controlling the opening of the counterbalance valve 200, the descent speed of a load such as an aerial work platform can be controlled, improving safety during descent.

[0044] It is understood that the proportional valve 400 is electrically connected to a controller, which includes an acquisition module, a first control module, and a second control module. The acquisition module is used to acquire the movement speed of the telescopic hydraulic cylinder 100. The acquisition module can acquire the retracted length of the load within a preset time period and calculate the actual speed based on the retracted length and the preset time period. A length sensor can be used to detect the retracted length within a preset time period, for example, detecting the retracted length within an interval of 2s-4s. The actual speed is calculated by dividing the retracted length by the interval. The first control module outputs an electrical signal based on the movement speed signal of the telescopic hydraulic cylinder 100 obtained by the acquisition module to control the opening of the proportional valve 400 and the switch valve 500. The second control module outputs an electrical signal based on the movement speed signal of the telescopic hydraulic cylinder 100 obtained by the acquisition module to control the start and stop of the emergency oil source 210 and the pressure of the output hydraulic oil.

[0045] In addition, an embodiment of the present invention further provides a control method for an emergency retraction system of an aerial work vehicle, comprising the following steps:

[0046] S1: The controller adjusts the opening of the proportional valve 400 to the minimum and switches the switch valve 500 to the on position, and then gradually increases the opening of the proportional valve 400;

[0047] S2: The controller detects the movement speed of the piston rod 110 and controls the opening of the proportional valve 400 and the start and stop of the emergency oil source 210.

[0048] In step S1, when the load needs to be retracted, the opening of the proportional valve 400 is first adjusted to the minimum to prevent the pressure in the pipeline from changing too much when the switch valve 500 is opened, causing impact on the proportional valve 400 and the compensator 800, thereby extending the service life of the equipment.

[0049] In step S2, the actual speed of the piston rod 110 during descent is obtained. Specifically, a length sensor can be installed on the boom of the aerial work vehicle. By collecting the boom length in real time as the load is lowered and outputting the length change within an interval, the actual descent speed is calculated. The actual speed is then compared with the preset speed, and PID adjustment is performed to output the adjustment variable data, which is used to control the opening of the proportional valve 400 and the start and stop of the emergency oil source 210. This ensures that the descent speed is consistent with the preset speed.

[0050] In some specific embodiments of the present invention, in step S2, when the movement speed of the piston rod 110, that is, the speed at which the load drops, increases with the opening of the proportional valve 400, it indicates that the proportional valve 400 and the switch valve 500 are working normally, and the hydraulic oil in the rodless chamber 130 flows to the rod chamber 120 through the proportional valve 400 and the switch valve 500, without starting the emergency oil source 210, and then continues to increase the opening of the proportional valve 400 until the movement speed of the piston rod 110 reaches a preset value. When the opening of the proportional valve 400 increases, the movement of the piston rod 110 If the speed is zero or remains constant, it indicates that the proportional valve 400 and the on-off valve 500 are malfunctioning and cannot be opened or fully opened. As a result, the hydraulic oil in the rodless chamber 130 cannot flow normally through the proportional valve 400 and the on-off valve 500 to the rod chamber 120. The emergency oil source 210 is then activated to gradually increase the hydraulic oil pressure flowing to the control port of the balancing valve 200, controlling the balancing valve 200 to open, allowing the hydraulic oil in the rodless chamber 130 to flow through the balancing valve 200 to the rod chamber 120 until the movement speed of the piston rod 110 reaches the preset value. This ensures operational safety in the event of failure of the proportional valve 400 and the on-off valve 500.

[0051] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. An emergency retraction system for an aerial work vehicle, characterized in that: include: A telescopic hydraulic cylinder (100) is provided with a piston rod (110) for lifting a load, wherein the piston rod (110) divides the interior of the telescopic hydraulic cylinder (100) into a rod chamber (120) and a rodless chamber (130); A balancing valve (200), wherein the outlet of the balancing valve (200) is connected to the rod chamber (120), the inlet of the balancing valve (200) is connected to the rodless chamber (130), and the control port of the balancing valve (200) is connected to an emergency oil source (210) for controlling the balancing valve (200); An oil return pipe (300) connected to the rod chamber (120) and used for receiving the returned hydraulic oil; A proportional valve (400), wherein the inlet of the proportional valve (400) is connected to the rodless chamber (130), the outlet of the proportional valve (400) is connected to the return oil pipe (300), the proportional valve (400) and the rodless chamber (130) are connected to a switch valve (500), the switch valve (500) is used to connect and close the oil circuit between the proportional valve (400) and the rodless chamber (130), the proportional valve (400) is electrically connected to a controller, the controller includes an acquisition module, a first control module, and a second control module, the acquisition module is used to acquire the movement speed of the piston rod (110), the first control module is used to control the opening of the proportional valve (400) and the switch valve (500) according to the speed acquired by the acquisition module, and the second control module is used to control the start and stop of the emergency oil source (210) according to the speed acquired by the acquisition module.

2. The emergency retraction system for an aerial work vehicle according to claim 1, characterized in that: The switch valve (500) is a two-position, two-way switch valve. When the switch valve (500) is in a closed state, hydraulic oil cannot flow from the rodless chamber (130) to the inlet of the proportional valve (400), but can flow from the inlet of the proportional valve (400) to the rodless chamber (130).

3. The emergency retraction system for an aerial work vehicle according to claim 2, characterized in that: The inlet of the proportional valve (400) is connected to a one-way valve (600), and the one-way valve (600) is connected to an oil supply pipe (610). Hydraulic oil can flow from the oil supply pipe (610) to the switch valve (500) through the one-way valve (600). The one-way valve (600) is used to prevent the hydraulic oil from flowing back from the switch valve (500) to the oil supply pipe (610).

4. The emergency retraction system for an aerial work vehicle according to claim 3, characterized in that: A throttle valve (700) is connected between the inlet of the balancing valve (200) and the rodless chamber (130), and the throttle valve (700) is used to limit the flow of hydraulic oil flowing from the rodless chamber (130) to the inlet of the balancing valve (200).

5. The emergency retraction system for an aerial work vehicle according to claim 4, characterized in that: A compensator (800) is connected between the outlet of the proportional valve (400) and the oil return pipe (300).

6. The emergency retraction system for an aerial work vehicle according to claim 5, characterized in that: The emergency oil source (210) can adjust the hydraulic oil pressure provided to the control port of the balancing valve (200) to control the opening of the balancing valve (200).

7. A control method for an emergency retraction system of an aerial work vehicle according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: the controller adjusts the opening of the proportional valve (400) to the minimum and switches the switch valve (500) to the on position, and then gradually increases the opening of the proportional valve (400); S2: The controller detects the movement speed of the piston rod (110), and controls the opening of the proportional valve (400) and the pressure of the hydraulic oil output by the emergency oil source (210).

8. The control method for the emergency retraction system of an aerial work vehicle according to claim 7, characterized in that: In step S2, when the movement speed of the piston rod (110) increases with the opening of the proportional valve (400), the opening of the proportional valve (400) is continuously increased until the movement speed of the piston rod (110) reaches a preset value. When the opening of the proportional valve (400) increases and the movement speed of the piston rod (110) is 0 or remains unchanged, the controller starts the emergency oil source (210) and gradually increases the pressure of the hydraulic oil flowing to the control port of the balancing valve (200) until the movement speed of the piston rod (110) reaches the preset value.

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