An emergency descent system and control method for an aerial work platform

Abstract

The present invention discloses an emergency descent system and control method for an aerial work platform, which relates to the field of aerial work platforms and includes: a telescopic hydraulic cylinder, a balance valve, a return oil pipe, and a proportional valve. A piston rod for lifting a load is provided inside the telescopic hydraulic cylinder, and the piston rod divides the interior of the telescopic hydraulic cylinder into a rod chamber and a rodless chamber; the inlet of the balance valve is connected to the rodless chamber, and the outlet of the balance valve is connected to an oil supply pipe; the return oil pipe is connected to the rod chamber, and the return oil pipe is connected to an emergency oil source for supplying hydraulic oil to the return oil pipe, and the return oil pipe is connected to the control port of the balance valve; the inlet of the proportional valve is connected to the rodless chamber, and the outlet of the proportional valve is connected to the return oil 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 particularly to an emergency descent system and control method for an aerial work platform. Background Art

[0002] Currently, an aerial work vehicle is a special-purpose special vehicle for transporting workers and equipment to high altitudes to install, maintain, and clean equipment located at high altitudes. Compared with traditional working methods such as scaffolding and ladders, it has advantages such as good working performance, high working efficiency, and working safety. Currently, it is widely used in infrastructure industries such as electricity, transportation, petrochemical, communication, and gardening. When the boom of the aerial work vehicle is lowered by gravity, the oil in the rodless cavity of the luffing cylinder passes through a two-position two-way switching valve, a reversing valve, a proportional valve, and a compensator and returns to the hydraulic oil tank. During use, the two-position two-way switching valve and the proportional valve for controlling the self-weight descent of the luffing may experience sticking where the spool cannot normally reverse, and the control wire harness may rub against the boom structure, resulting in damage or breakage of the wire harness and abnormal transmission of electrical signals. This will cause the oil in the luffing cylinder to not flow back, and will result in personnel not being able to safely descend from the air to the ground. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention provides an emergency descent system for an aerial work platform, which enables personnel to safely descend from the air to the ground in the event of a proportional valve failure.

[0004] An emergency descent system for an aerial work platform according to an embodiment of the present invention includes: a telescopic hydraulic cylinder, a balance valve, a return oil pipe, and a proportional valve. A piston rod for lifting a load is provided inside the telescopic hydraulic cylinder, and the piston rod divides the interior of the telescopic hydraulic cylinder into a rod cavity and a rodless cavity; the inlet of the balance valve is connected to the rodless cavity, and the outlet of the balance valve is connected to an oil supply pipe; the return oil pipe is connected to the rod cavity, and the return oil pipe is connected to an emergency oil source for supplying hydraulic oil to the return oil pipe, and the return oil pipe is connected to the control port of the balance valve; the inlet of the proportional valve is connected to the rodless cavity, and a switching valve is connected between the proportional valve and the rodless cavity, and the switching valve is used to connect and disconnect the oil circuit between the proportional valve and the rodless cavity. The outlet of the proportional valve is connected to the return oil pipe; the proportional valve is electrically connected to a controller, and 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, the first control module is used to control the opening degrees of the proportional valve and the switching valve 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 according to the speed acquired by the acquisition module.

[0005] An emergency descent system for an aerial work platform according to an embodiment of the present invention has at least the following beneficial effects: The controller can open the proportional valve to allow the hydraulic oil in the rodless cavity to enter the rod cavity to control the descent of the piston rod. When the proportional valve fails, it can also control the balance valve to make the piston rod descend. The load is controlled to descend through two control methods. When one control method fails, the other method can still be used to control the load to descend, effectively improving the safety of aerial work.

[0006] According to some embodiments of the present invention, the switching valve is a two-position two-way bidirectional cut-off switching valve. A first one-way valve is connected to the inlet of the balance valve. The first one-way valve is connected to the oil supply pipe. The hydraulic oil can flow from the oil supply pipe through the first one-way valve to the rodless cavity. The first one-way valve is used to prevent the hydraulic oil from flowing back from the rodless cavity to the oil supply pipe.

[0007] According to some embodiments of the present invention, a second one-way valve is connected to the inlet of the proportional valve. The second one-way valve is connected to the oil supply pipe. The hydraulic oil can flow from the oil supply pipe to the switching valve through the second one-way valve. The second one-way valve is used to prevent the hydraulic oil from flowing back from the switching valve to the oil supply pipe.

[0008] According to some embodiments of the present invention, a compensator is connected between the outlet of the proportional valve and the return oil pipe.

[0009] According to some embodiments of the present invention, the emergency oil source can adjust the hydraulic oil pressure provided to the return oil pipe to control the opening degree of the balance valve.

[0010] The present invention also provides a control method for an emergency descent system of an aerial work platform, including the following steps:

[0011] S1: The controller adjusts the opening degree of the proportional valve to the minimum and switches the switching valve to the on position, and then gradually increases the opening degree of the proportional valve;

[0012] S2: The controller detects the movement speed of the piston rod and controls the opening degree of the proportional valve and the hydraulic oil pressure output by the emergency oil source.

[0013] According to some embodiments of the present invention, in step S2, when the movement speed of the piston rod increases with the increase of the opening degree of the proportional valve, the opening degree of the proportional valve is continuously increased until the movement speed of the piston rod reaches a preset value. When the opening degree of the proportional valve increases and the movement speed of the piston rod is 0 or unchanged, the controller starts the emergency oil source and gradually increases the hydraulic oil pressure flowing to the return oil pipe until the movement speed of the piston rod reaches the preset value.

[0014] An emergency descent system for an aerial work platform according to an embodiment of the present invention has at least the following beneficial effects:

[0015] (1) On the basis of using a proportional valve to control the descent action, a backup emergency oil source and a balance valve are added. When the proportional valve or the switching valve fails, the balance valve can still be used to export the hydraulic oil in the rodless cavity to control the descent of the load;

[0016] (2) The emergency oil source simultaneously supplies hydraulic oil to the control port of the balance valve and the rod cavity. In the case where the load is small and cannot descend by its own weight, the hydraulic oil in the rod cavity can push the piston rod to retract to achieve the descent of the load;

[0017] (3) By setting a compensator, when the load changes, the hydraulic oil flow rate through the proportional valve is proportional to the opening degree of the proportional valve, so that the load can descend at a uniform speed.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the drawings and embodiments, where:

[0020] Figure 1 is a schematic diagram of an embodiment of the present invention.

[0021] Reference numerals in the drawings:

[0022] Telescopic hydraulic cylinder 100, piston rod 110, rod cavity 120, rodless cavity 130;

[0023] Balance valve 200, oil supply pipe 201, emergency oil source 210, second check valve 220;

[0024] Return oil pipe 300;

[0025] Proportional valve 400;

[0026] Switching valve 500;

[0027] Second check valve 600;

[0028] Compensator 700. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0030] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms related to orientation, such as up and down, etc., is based on the orientation or positional relationship shown in the drawings. This is 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. Therefore, it should not be construed as a limitation to the present invention.

[0031] In the description of the present invention, "a plurality of" means more than two. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or the sequence relationship of the indicated technical features.

[0032] In the description of the present invention, unless otherwise clearly defined, terms such as "arrangement", "installation", and "connection" should be understood in a broad sense. Those skilled in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0033] As shown in the specification appendix Figure 1As shown in the figure, an emergency descent system for an aerial work platform provided by an embodiment of the present application includes: a telescopic hydraulic cylinder 100, a balance valve 200, a return oil pipe 300, and a proportional valve 400; a piston rod 110 for lifting a 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; one end of the piston rod 110 away from the piston is connected to loads such as a boom and an aerial work platform; the inlet of the balance valve 200 is connected to the rodless chamber 130 through a hydraulic pipeline, the outlet of the balance valve 200 is connected to an oil supply pipe 201 through a hydraulic pipeline, the return oil pipe 300 is connected to the rod chamber 120, and the return oil pipe 300 is connected to an emergency oil source 210 for supplying hydraulic oil to the return oil pipe 300; the return oil pipe 300 is connected to the control port of the balance valve 200. After the emergency oil source 210 is started, it supplies hydraulic oil to the return oil pipe 300, and the pressure energy in the return oil pipe 300 controls the opening of the balance valve 200. The piston rod 110 is jointly affected by gravity and the hydraulic oil pressure in the rod chamber 120, so as to squeeze the hydraulic oil in the rodless chamber 130. The hydraulic oil enters the rod chamber 120 from the rodless chamber 130 through the balance valve 200. In this way, the oil in the rodless chamber 130 flows out and the oil in the rod chamber 120 flows in, realizing the retraction of the piston rod 110 and the load. The emergency oil source 210 should be kept in a standby state during normal use. When the proportional valve 400 fails and loads such as the aerial work platform cannot descend, the emergency oil source 210 switches from the standby state to the start state to provide hydraulic oil pressure to the control port of the balance valve 200 and the rod chamber 120. The balance valve 200 can keep the flow rate of the hydraulic oil flowing through the balance valve 200 approximately constant under the condition of load change. Therefore, using the balance valve 200 can effectively ensure that the piston rod 110 moves downward uniformly in the telescopic hydraulic cylinder 100 and the load descends uniformly. The inlet of the proportional valve 400 is connected to the rodless chamber 130, and a switching valve 500 is connected between the proportional valve 400 and the rodless chamber 130. The switching valve 500 is used to connect and disconnect the oil circuit between the proportional valve 400 and the rodless chamber 130. The switching valve 500 has good sealing performance. When descent is not required, the switching valve 500 is in a closed state to prevent the hydraulic oil in the rodless chamber 130 from passing through the proportional valve 400, so that loads such as the aerial work platform can stay in the air without descending for aerial work. The outlet of the proportional valve 400 is connected to the return oil pipe 300. The specific structures of the balance valve 200 and the 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 affected by gravity and squeezes the hydraulic oil in the rodless chamber 130. The hydraulic oil enters the return oil pipe 300 from the rodless chamber 130 through the proportional valve 400. Since the rod chamber 120 is connected to the return oil pipe 300, part of the hydraulic oil will enter the rod chamber 120, realizing the retraction of the piston rod 110 and the load.During descent, the proportional valve 400 is preferentially opened to control the descent of the load. When the proportional valve 400 fails, the balance valve 200 is then controlled to make the load descend. The load descent is controlled by two control methods. When one control method fails, the other method can still be used to control the load descent, effectively improving the safety of aerial work. 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 obtain the movement speed of the telescopic hydraulic cylinder 100. The acquisition module can obtain the retraction length of the load within a preset time period, and calculate the actual speed based on the retraction length and the preset time period. Among them, a length sensor can be used to detect the retraction length within the preset time period. For example, the retraction length is detected at intervals of 2s - 4s, and the actual speed is calculated by dividing the retraction length by the interval time. The first control module outputs an electrical signal to control the opening degrees of the proportional valve 400 and the switching valve 500 according to the movement speed signal of the telescopic hydraulic cylinder 100 obtained by the acquisition module. The second control module outputs an electrical signal to control the start and stop of the emergency oil source 210 and the pressure of the output hydraulic oil according to the movement speed signal of the telescopic hydraulic cylinder 100 obtained by the acquisition module.

[0034] See Figure 1 As shown, it can be understood that the switching valve 500 is a two-position two-way normally-closed switching valve. When the switching valve 500 is in the closed state, hydraulic oil cannot flow from the rodless cavity 130 to the inlet of the proportional valve 400 and cannot flow from the inlet of the proportional valve 400 to the rodless cavity 130. The inlet of the balance valve 200 is connected to a first check valve 220, and the first check valve 220 is connected to the oil supply pipe 201. Hydraulic oil can flow from the oil supply pipe 201 through the first check valve 220 to the rodless cavity 130. Hydraulic oil can flow through the first check valve 220 into the rodless cavity 130, causing the piston rod 110 to drive the load to move towards the side of the rod cavity 120 to realize the ascent of loads such as aerial work platforms. The first check valve 220 is used to prevent hydraulic oil from flowing back from the rodless cavity 130 to the oil supply pipe 201 during the lifting and stationary processes of the load. So that loads such as aerial work platforms can be kept in the air without descending to carry out aerial work normally.

[0035] See Figure 1As shown, it can be understood that a second check valve 600 is connected to the inlet of the proportional valve 400. The second check valve 600 is connected to the oil supply pipe 201. The hydraulic oil can flow from the oil supply pipe 201 to the switching valve 500 through the second check valve 600. When the load such as an aerial work platform rises, the oil supply pipe 201 supplies the hydraulic oil. The hydraulic oil passes through the second check valve 600 and then enters the rodless cavity 130 through the switching valve 500 to push the piston rod 110 to drive the load to rise. When the load descends and the switching valve 500 is opened, the hydraulic oil flows from the rodless cavity 130 to the inlet of the proportional valve 400. The second check valve 600 is used to prevent the hydraulic oil from flowing back from the switching valve 500 to the oil supply pipe 201, so that the hydraulic oil can enter the rod chamber 120 and the oil return pipe 300 under the push of the gravity of the load.

[0036] See Figure 1 As shown, it can be understood that a compensator 700 is connected between the outlet of the proportional valve 400 and the oil return pipe 300. Due to the characteristics of the balance valve 200 itself, the flow rate through the balance valve 200 has nothing to do with the driving force of the load on the piston rod 110. Therefore, when loads of different weights descend, the flow rate through the balance valve 200 remains roughly the same. However, the proportional valve 400 does not have this characteristic. Therefore, the compensator 700 is added to ensure that at the same opening of the proportional valve 400, the flow rate of the hydraulic oil through the proportional valve 400 is an approximate constant value, which does not change with the fluctuation of the load pressure, and ensures that the flow rate through the proportional valve 400 changes proportionally to the input electrical signal, so as to better control the descending speed of loads of different weights.

[0037] See Figure 1 As shown, it can be understood that the emergency oil source 210 can adjust the pressure of the hydraulic oil supplied to the oil return pipe 300 to adjust the pressure in the control port of the balance valve 200 and the rod chamber 120, and control the descending speed of the load such as an aerial work platform. The emergency oil source 210 can be composed of an independent power supply and an independent hydraulic pump to ensure that the emergency oil source 210 can work independently in the case of power failure of other equipment such as the main power supply. The start-stop and rotation speed of the independent hydraulic pump are controlled by the controller. By controlling the opening of the balance valve 200, the descending speed of the load such as an aerial work platform can be controlled, and the safety during descending can be increased.

[0038] In addition, an embodiment of the present invention also provides a control method for an emergency descending system of an aerial work platform, including the following steps:

[0039] S1: The controller adjusts the opening of the proportional valve 400 to the minimum and switches the switching valve 500 to the on position, and then gradually increases the opening of the proportional valve 400;

[0040] S2: The controller detects the movement speed of the piston rod 110 and controls the opening of the proportional valve 400 and the start-stop of the emergency oil source 210.

[0041] In step S1, when the load needs to be retracted, first adjust the opening of the proportional valve 400 to the minimum to prevent excessive pressure changes in the pipeline when the switching valve 500 is opened, which may impact the proportional valve 400 and the compensator 700, and to extend the service life of the equipment.

[0042] In step S2, obtain the actual speed of the piston rod 110 during descent. Specifically, a length sensor can be set on the boom of the aerial work platform. By collecting the length of the boom in real time when the load is descending and outputting the length change within an interval time, calculate the actual descent speed. Then compare the actual speed with the preset speed and perform PID adjustment to output the adjustment variable data for controlling the opening of the proportional valve 400 and the start and stop of the emergency oil source 210, so that the descent speed is consistent with the preset speed.

[0043] In some specific embodiments of the present invention, in step S2, when the movement speed of the piston rod 110, i.e., the descent speed of the load, increases with the increase of the opening of the proportional valve 400, it indicates that the proportional valve 400 and the switching valve 500 are working properly, and the hydraulic oil in the rodless cavity 130 flows through the proportional valve 400 and the switching valve 500 to the rod cavity 120. There is no need to start the emergency oil source 210, and then continue to increase the opening of the proportional valve 400 until the movement speed of the piston rod 110 reaches the 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, it indicates that the proportional valve 400 and the switching valve 500 are malfunctioning and cannot be opened or cannot be fully opened, and the hydraulic oil in the rodless cavity 130 cannot flow through the proportional valve 400 and the switching valve 500 to the rod cavity 120 normally. Then start the emergency oil source 210, gradually increase the hydraulic oil pressure flowing to the control port of the balance valve 200 and the rod cavity 120 to control the balance valve 200 to open, so that the hydraulic oil in the rodless cavity 130 flows through the balance valve 200 to the rod cavity 120 until the movement speed of the piston rod 110 reaches the preset value, ensuring operational safety in the event of the failure of the proportional valve 400 and the switching valve 500.

[0044] The embodiments of the present invention have been 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 without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art.

Claims

1. An emergency descent system for an aerial work platform, characterized in that, Comprising: A telescopic hydraulic cylinder (100) with a piston rod (110) inside for lifting a load, and the piston rod (110) divides the interior of the telescopic hydraulic cylinder (100) into a rod chamber (120) and a rodless chamber (130); A balance valve (200), the inlet of the balance valve (200) is connected to the rodless chamber (130), and the outlet of the balance valve (200) is connected with an oil supply pipe (201); A return oil pipe (300) connected to the rod chamber (120), the return oil pipe (300) is connected with an emergency oil source (210) for supplying hydraulic oil to the return oil pipe (300), and the return oil pipe (300) is connected to the control port of the balance valve (200); A proportional valve (400), the inlet of the proportional valve (400) is connected to the rodless chamber (130), the proportional valve (400) and the rodless chamber (130) are connected with a switching valve (500), the switching valve (500) is used to connect and disconnect the oil circuit between the proportional valve (400) and the rodless chamber (130), the outlet of the proportional valve (400) is connected to the return oil pipe (300), the proportional valve (400) is electrically connected to a controller, and 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 degrees of the proportional valve (400) and the switching 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 descent system for an aerial work platform according to claim 1, wherein: The switching valve (500) is a two-position two-way bi-directional cut-off switching valve, the inlet of the balance valve (200) is connected with a first one-way valve (220), the first one-way valve (220) is connected with the oil supply pipe (201), and the hydraulic oil can flow from the oil supply pipe (201) through the first one-way valve (220) to the rodless chamber (130), and the first one-way valve (220) is used to prevent the hydraulic oil from flowing back from the rodless chamber (130) to the oil supply pipe (201).

3. The emergency descent system of an aerial work platform according to claim 2, characterized in that: The inlet of the proportional valve (400) is connected with a second one-way valve (600), the second one-way valve (600) is connected with the oil supply pipe (201), and the hydraulic oil can flow from the oil supply pipe (201) to the switching valve (500) through the second one-way valve (600), and the second one-way valve (600) is used to prevent the hydraulic oil from flowing back from the switching valve (500) to the oil supply pipe (201).

4. The emergency descent system for an aerial work platform according to claim 3, characterized in that: A compensator (700) is connected between the outlet of the proportional valve (400) and the return oil pipe (300).

5. The emergency descent system for an aerial work platform according to claim 4, characterized in that: The emergency oil source (210) can adjust the hydraulic oil pressure supplied to the return oil pipe (300) to control the opening degree of the balance valve (200).

6. The control method of an emergency descent system for an aerial work platform according to any one of claims 1 to 5, characterized in that, Comprising the following steps: S1: The controller adjusts the opening degree of the proportional valve (400) to the minimum and switches the switching valve (500) to the on position, and then gradually increases the opening degree of the proportional valve (400); S2: The controller detects the movement speed of the piston rod (110), and controls the opening degree of the proportional valve (400) and the hydraulic oil pressure output by the emergency oil source (210).

7. The control method of an emergency descent system for an aerial work platform according to claim 6, characterized in that, In the step S2, when the movement speed of the piston rod (110) increases with the increase of the opening degree of the proportional valve (400), the opening degree of the proportional valve (400) is continuously increased until the movement speed of the piston rod (110) reaches a preset value. When the opening degree 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 hydraulic oil pressure flowing to the control port of the balance valve (200) until the movement speed of the piston rod (110) reaches the preset value.

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