Luffing control system

Abstract

A luffing control system. It solves the problems of unreliable control and poor stability of the existing luffing system. It includes an oil tank, a hydraulic pump, a first reversing valve, a second reversing valve, a proportional flow valve and a working cylinder. The working cylinder includes a rodless cavity and a rod cavity. The hydraulic pump is used to input the hydraulic oil in the oil tank into the rodless cavity or the rod cavity of the working cylinder through the first reversing valve. The first reversing valve has a first position connected to the rodless cavity of the working cylinder through the second reversing valve, a second position with a middle position cut-off, and a third position connected to the rod cavity of the working cylinder. The second reversing valve has a first position for connecting the rodless of the working cylinder and a second position for cut-off. The proportional flow valve is connected to the rodless cavity of the working cylinder through the second reversing valve when the first reversing valve is in the third position, and matches the oil return flow of the rodless cavity and the oil inlet flow of the rod cavity. The invention has the advantages of simple structure, stable performance and long service life.

Description

Technical Field

[0001] The present invention relates to a luffing control system. Background Art

[0002] With the increasing demand for efficiency in the construction industry, the demand for aerial work platform equipment is becoming wider. It is commonly used for performing high-altitude operations such as exterior wall maintenance, high-rise building construction, and street lamp installation. The existing luffing lowering systems of aerial work platform products have two luffing lowering modes: gravity lowering and power lowering. Each of these two luffing lowering modes has its own advantages and disadvantages.

[0003] In the gravity lowering system, the hydraulic pump supplies pressure oil, the solenoid valve changes its direction, and the solenoid valve is in the right position. After the pressure oil passes through the directional valve, it opens the check valve and enters the rodless cavity of the oil cylinder, so that the upward movement of the oil cylinder can achieve the lifting of the luffing action; when the solenoid valve is cut off, the oil cylinder can stop at a certain designated position; when luffing down, the load exerts a force on the oil cylinder due to gravity, and the hydraulic oil in the rodless cavity of the oil cylinder flows back to the fuel tank through the solenoid valve, realizing the lowering of the luffing oil cylinder. The advantage of the gravity lowering system is that the lowering of the luffing oil cylinder can be achieved even when the vehicle engine is not started, effectively reducing energy consumption; at the same time, the gravity lowering of the luffing oil cylinder is affected by the load. When the load is large, the force exerted by gravity on the luffing oil cylinder is large, and the lowering speed is relatively fast, which poses a safety hazard. When the load is small, the force exerted by gravity on the luffing oil cylinder is small, and the lowering speed will be very slow, resulting in a reduction in work efficiency.

[0004] In the power lowering system (see attached Figure 1 ), the hydraulic pump 2 supplies pressure oil, the proportional valve 3 changes its direction to the left position, the pressure oil reaches the balance valve 4 through port A of the proportional valve 3, enters the rodless cavity of the oil cylinder 6 through the balance valve 4. At the same time, the pressure oil opens the balance valve 5 through the control port of the balance valve 5, and the hydraulic oil in the rodless cavity of the oil cylinder 6 flows back to the fuel tank through the balance valve 5 and port B of the proportional valve 3, realizing the extension of the oil cylinder. The hydraulic pump 2 supplies pressure oil, the proportional valve 3 changes its direction to the right position, the pressure oil reaches the balance valve 5 through port B of the proportional valve 3, enters the rodless cavity of the oil cylinder 6 through the balance valve 5. At the same time, the pressure oil opens the balance valve 4 through the control port of the balance valve 4, and the hydraulic oil in the rodless cavity of the oil cylinder 6 flows back to the fuel tank through the balance valve 4 and port A of the proportional valve 3, realizing the retraction of the oil cylinder. The advantages and disadvantages of the power lowering system are that a certain amount of pressure oil is required to open the corresponding balance valve on the return oil path through the control port during the extension and retraction of the oil cylinder, which will increase energy consumption; at the same time, during the luffing lowering process, the load force changes greatly, resulting in the balance valve being prone to jitter, causing the luffing oil cylinder to fall unstably. Summary of the Invention

[0005] To solve the problems of unreliable control and poor stability of the existing luffing system in the background art, the present invention provides a luffing control system.

[0006] The technical solution of the present invention is: a luffing control system, including an oil tank, a hydraulic pump, a first reversing valve, a second reversing valve, a proportional flow valve and a working cylinder, and the working cylinder includes a rodless cavity and a rod cavity;

[0007] The hydraulic pump is used to input the hydraulic oil in the oil tank into the rodless cavity or the rod cavity of the working cylinder through the first reversing valve;

[0008] The first reversing valve has a first position connected to the rodless cavity of the working cylinder through the second reversing valve, a second position with a central cut-off, and a third position connected to the rod cavity of the working cylinder;

[0009] The second reversing valve has a first position for connecting the rodless part of the working cylinder and a second position for cut-off;

[0010] The proportional flow valve is connected to the rodless cavity of the working cylinder through the second reversing valve when the first reversing valve is in the third position, and matches the oil return flow of the rodless cavity and the oil inlet flow of the rod cavity.

[0011] As an improvement of the present invention, when the second reversing valve is in the first position, it has a first state of receiving the hydraulic oil of the hydraulic pump and inputting it into the rodless cavity of the working cylinder, and a second state of connecting the rodless cavity of the working cylinder to the oil tank through the proportional flow valve when the first reversing valve is in the third position.

[0012] As a further improvement of the present invention, a low-pressure overflow valve is also provided, and the low-pressure overflow valve is arranged between the rod cavity of the working cylinder and the oil tank.

[0013] As a further improvement of the present invention, an electro-hydraulic proportional overflow valve is also provided, and the electro-hydraulic proportional overflow valve is arranged between the rod cavity of the working cylinder and the oil tank.

[0014] As a further improvement of the present invention, a check valve is arranged between the first reversing valve and the second reversing valve.

[0015] As a further improvement of the present invention, when the first reversing valve is in the third position, the proportional flow valve intercepts the pressure oil between the check valve and the second reversing valve and is connected to the oil tank.

[0016] As a further improvement of the present invention, the proportional flow valve includes a flow reversing valve and a compensation valve, and the flow reversing valve receives the pressure oil at the rodless cavity of the working cylinder and is connected to the oil tank through the compensation valve.

[0017] As a further improvement of the present invention, the oil inlet of the compensation valve is communicated with the oil outlet of the flow direction change valve. The pressure oil at the oil outlet of the flow direction change valve is connected to the compensation valve spring chamber. The control chamber of the compensation valve receives the pressure oil at the rodless chamber of the working cylinder, and the pressure in the compensation valve spring chamber cooperate to jointly control the opening of the compensation valve.

[0018] As a further improvement of the present invention, both the spring chamber and the control chamber of the flow direction change valve receive the pressure oil at the rodless chamber of the working cylinder.

[0019] As a further improvement of the present invention, the first change-over valve is a proportional change-over valve.

[0020] The beneficial effects of the present invention are as follows: The first change-over valve and the second change-over valve are provided. By changing the direction of the first change-over valve and the second change-over valve, the product can reliably supply oil or drain oil to the working cylinder. Through the setting of the proportional flow valve, the system is more stable and reliable when lowering. The present invention solves the problems of slow speed of gravity lowering, high energy consumption and easy jitter during power lowering, and at the same time enables the system to efficiently, energy-savingly and stably realize the lifting of the working platform. It has the advantages of simple structure, reliable action, high efficiency, energy saving, stable performance and long service life. Description of the Drawings

[0021] Att Figure 1 is the hydraulic schematic diagram of the existing power lowering system.

[0022] Att Figure 2 is the hydraulic schematic diagram of the embodiment of the present invention.

[0023] In the figure, 1 is the fuel tank; 2 is the hydraulic pump; 3 is the first change-over valve; 4 is the one-way valve; 5 is the second change-over valve; 6 is the working cylinder; 61 is the rodless chamber; 62 is the rod chamber; 7 is the low-pressure overflow valve; 8 is the proportional flow valve; 81 is the flow direction change valve; 82 is the compensation valve. Detailed Embodiments

[0024] The following further describes the embodiments of the present invention with reference to the drawings:

[0025] As shown Figure 2 A luffing control system includes a fuel tank 1, a hydraulic pump 2, a first change-over valve 3, a second change-over valve 5, a proportional flow valve 8 and a working cylinder 6. The working cylinder includes a rodless chamber 61 and a rod chamber 62;

[0026] The hydraulic pump is used to input the hydraulic oil in the fuel tank into the rodless chamber or the rod chamber of the working cylinder through the first change-over valve;

[0027] The first change-over valve has a first position connected to the rodless chamber of the working cylinder through the second change-over valve, a second position with a central cut-off, and a third position connected to the rod chamber of the working cylinder;

[0028] A second reversing valve having a first position for connecting the rodless side of the working cylinder and a second position for shutting off.

[0029] A proportional flow valve is connected to the rodless chamber of the working cylinder through the second reversing valve when the first reversing valve is in the third position, and matches the oil return flow of the rodless chamber and the oil inlet flow of the rod chamber. The beneficial effects of the present invention are as follows: The first reversing valve and the second reversing valve are provided, and through the reversing of the first reversing valve and the second reversing valve, the product can reliably supply oil or drain oil to the working cylinder. Through the setting of the proportional flow valve, the system is more stable and reliable when lowering. The present invention solves the problems of slow gravity lowering speed, high energy consumption and easy jitter during power lowering, and at the same time enables the system to efficiently, energy-savingly and stably realize the lifting of the working platform, and has the advantages of simple structure, reliable, efficient, energy-saving operation, stable performance and long service life.

[0030] In the luffing control system of the present invention, pressure oil is supplied by a hydraulic pump 2. The first reversing valve 3 is switched to the left position. The pressure oil passes through port A of the first reversing valve 3, opens the one-way valve 4, and the second reversing valve 5 works in the right position. The pressure oil enters the rodless chamber 61 of the working cylinder 6 through the second reversing valve 5. The oil in the rod chamber 62 of the working cylinder 6 flows back to the oil tank 1 through the first reversing valve 3. At this time, the working cylinder extends, that is, the lifting of the luffing action; by changing the control current of the first reversing valve 3, the flow rate supplied to the system can be controlled to change the lifting speed. Specifically, the first reversing valve 3 is a proportional reversing valve. More specifically, the first reversing valve is a hydraulically controlled proportional reversing valve or an electrically controlled proportional reversing valve. More specifically, the first reversing valve is a three-position four-way reversing valve.

[0031] In the luffing control system of the present invention, after the working oil cylinder extends in place, the second reversing valve is in the right position and the first reversing valve is in the middle position without supplying oil, realizing the high-position locking of the working platform, which is convenient for the staff to work. When performing the lowering action, the hydraulic pump 2 supplies pressure oil. The first reversing valve 3 reverses to the right position to work, and the pressure oil enters the rod chamber 62 of the working oil cylinder 6 through port B of the first reversing valve 3; the second reversing valve 5 reverses to the left position to work, and the proportional flow valve 8 reverses to the right position to work. At this time, the hydraulic oil in the rodless chamber 61 of the working oil cylinder 6 flows back to the oil tank through the second reversing valve 5 and the proportional flow valve 8; realizing the retraction of the working oil cylinder 6, that is, the lowering of the luffing; a proportional flow valve 8 is provided between the second reversing valve 5 and the one-way valve 4, and the through-flow of the proportional flow valve 8 can be controlled by changing the current, achieving the matching of the oil return in the rodless chamber and the oil inlet flow in the rod chamber of the working oil cylinder 6, thereby ensuring the stability of the oil cylinder retraction and eliminating the jitter problem of the luffing lowering. A low-pressure overflow valve 7 is provided between the first reversing valve 3 and the rod chamber 62 of the working oil cylinder 6. The set pressure of the low-pressure overflow valve 7 is very low, ensuring that the system controls the lowering of the working oil cylinder at a very low constant pressure, which can effectively reduce the energy consumption of the system. At the same time, the low-pressure overflow valve 7 can also be replaced with an electro-hydraulic proportional overflow valve, and the pressure setting value of this overflow valve can be adjusted by changing the control current. In the working condition where the luffing bears a large load, under the action of gravity, at this time, the set value of the overflow valve is lowered by changing the current to reduce the system working pressure. If the load is large enough, the overflow value can even be set to zero, making the luffing completely rely on gravity to lower.

[0032] When the second reversing valve is in the first position, it has a first state of receiving the hydraulic oil of the hydraulic pump and inputting it into the rodless chamber of the working oil cylinder and a second state of connecting the rodless chamber of the working oil cylinder to the oil tank through the proportional flow valve when the first reversing valve is in the third position. Such a structure can realize the telescopic action of the working oil cylinder through the state change of the second reversing valve, making the product action stable and reliable.

[0033] The present invention is also provided with a low-pressure overflow valve 7, and the low-pressure overflow valve is arranged between the rod chamber of the working oil cylinder and the oil tank. The present invention is also provided with an electro-hydraulic proportional overflow valve (not shown in the drawing), and the electro-hydraulic proportional overflow valve is arranged between the rod chamber of the working oil cylinder and the oil tank. The setting of the low-pressure overflow valve or the electro-hydraulic proportional overflow valve enables the product to control the lowering of the working oil cylinder under a constant pressure, which can effectively reduce the energy consumption of the system. The electro-hydraulic proportional overflow valve can adjust the pressure setting value of this overflow valve by changing the control current. In the working condition where the luffing bears a large load, under the action of gravity, at this time, the set value of the overflow valve is lowered by changing the current to reduce the system working pressure. If the load is large enough, the overflow value can even be set to zero, making the luffing completely rely on gravity to lower, that is, reducing the energy consumption, and also making the luffing lowering stable and controllable, and the system operation more stable.

[0034] A check valve 4 is provided between the first reversing valve and the second reversing valve. Specifically, when the first reversing valve is in the third position, the proportional flow valve intercepts the pressure oil between the check valve and the second reversing valve and connects it to the oil tank. Such a structure enables the working cylinder to reliably drain oil through the proportional flow valve, ensuring reliable lowering of the system.

[0035] The proportional flow valve 8 includes a flow reversing valve 81 and a compensation valve 82. The flow reversing valve receives the pressure oil at the rodless cavity of the working cylinder and is connected to the oil tank through the compensation valve. Specifically, the spring chamber and the control chamber of the flow reversing valve both receive the pressure oil at the rodless cavity of the working cylinder. More specifically, the oil inlet of the compensation valve is communicated with the oil outlet of the flow reversing valve, the pressure oil at the oil outlet of the flow reversing valve is connected to the spring chamber of the compensation valve, and the control chamber of the compensation valve receives the pressure oil at the rodless cavity of the working cylinder, and the pressure in the spring chamber of the compensation valve cooperate to jointly control the opening of the compensation valve. Such a structure can change the current to control the flow rate of the proportional flow valve, achieving a balance between the oil return of the rodless cavity and the oil inlet flow of the rod end cavity of the working cylinder, thereby ensuring stable retraction of the working cylinder and eliminating the jitter problem during the lowering process of the luffing. More specifically, the output flow can be controlled through the interaction between the compensation valve and the flow reversing valve, making the working cylinder fall more smoothly. More specifically, the opening size of the flow reversing valve is controlled in an electric control manner.

[0036] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It 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, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In addition, in the description of the present invention, unless otherwise stated, the meaning of "multiple" is two or more.

[0038] Notice to all technical personnel: Although the present invention has been described according to the above specific embodiments, the inventive concept of the present invention is not limited to this invention alone. Any modification that utilizes the inventive concept of the present invention will be included within the scope of protection of the patent right of this patent.

Claims

1. A luffing control system, characterized in that : It includes an oil tank, a hydraulic pump, a first reversing valve, a second reversing valve, a proportional flow valve and a working cylinder. The working cylinder includes a rodless chamber and a rod chamber; The hydraulic pump is used to input the hydraulic oil in the oil tank into the rodless chamber or the rod chamber of the working cylinder through the first reversing valve; The first reversing valve has a first position connected to the rodless chamber of the working cylinder through the second reversing valve, a second position with a central cutoff, and a third position connected to the rod chamber of the working cylinder; The second reversing valve has a first position for connecting the rodless part of the working cylinder and a second position for cutoff; The proportional flow valve is connected to the rodless chamber of the working cylinder through the second reversing valve when the first reversing valve is in the third position, and matches the oil return flow of the rodless chamber and the oil inlet flow of the rod chamber. The proportional flow valve includes a flow reversing valve and a compensation valve. The flow reversing valve receives the pressure oil at the rodless chamber of the working cylinder and is connected to the oil tank through the compensation valve. The oil inlet of the compensation valve is connected to the oil outlet of the flow reversing valve. The pressure oil at the oil outlet of the flow reversing valve is connected to the spring chamber of the compensation valve. The control chamber of the compensation valve receives the pressure oil at the rodless chamber of the working cylinder and cooperates with the pressure in the spring chamber of the compensation valve to jointly control the opening of the compensation valve. The spring chamber and the control chamber of the flow reversing valve both receive the pressure oil at the rodless chamber of the working cylinder.

2. The luffing control system according to claim 1, characterized in that When the second reversing valve is in the first position, it has a first state of receiving the hydraulic oil of the hydraulic pump and inputting it into the rodless chamber of the working cylinder, and a second state of connecting the rodless chamber of the working cylinder to the oil tank through the proportional flow valve when the first reversing valve is in the third position.

3. The luffing control system according to claim 1, characterized in that A low-pressure overflow valve is also provided, and the low-pressure overflow valve is arranged between the rod chamber of the working cylinder and the oil tank.

4. The luffing control system according to claim 1, characterized in that An electro-hydraulic proportional overflow valve is also provided, and the electro-hydraulic proportional overflow valve is arranged between the rod chamber of the working cylinder and the oil tank.

5. The luffing control system according to claim 1, characterized in that A check valve is arranged between the first reversing valve and the second reversing valve.

6. The luffing control system according to claim 5, characterized in that When the first reversing valve is in the third position, the proportional flow valve intercepts the pressure oil between the check valve and the second reversing valve and is connected to the oil tank.

7. The luffing control system according to claim 1, characterized in that The first reversing valve is a proportional reversing valve.

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