A control method for a dual oil circuit control system for lifting a forward-reaching forklift

Abstract

The present invention discloses a dual oil circuit control system for lifting a reach-forklift, comprising an oil pump, an oil tank, a front hydraulic cylinder and a side hydraulic cylinder, comprising a front proportional control valve group and a side proportional control valve group connected in parallel, wherein the working oil port of the front proportional control valve group is connected to the rodless chamber of the front hydraulic cylinder, and the working oil port of the side proportional control valve group is connected to the rodless chamber of the side hydraulic cylinder, and further comprising an altimeter, a front pressure sensor, a side pressure sensor and a temperature sensor which are communicatively connected to a controller, and the controller controls the opening of the front proportional control valve group and the side proportional control valve group according to the height detection result, the pressure detection result and the temperature detection result. The control accuracy and controllability are improved, and the dual oil circuit lifting is adopted to improve the balance and efficiency of cylinder changing, and the descending speed and the bottoming efficiency of the side hydraulic cylinder are increased, the efficiency of the whole machine is improved, the buffering mode is changed, the useless work of the oil is reduced, and the heating of the system is reduced. The present invention also discloses a control method for applying the above-mentioned dual oil circuit control system for lifting a reach-forklift.

Description

Technical Field

[0001] The present invention relates to the field of forklift equipment, and in particular to a dual oil circuit control system for lifting and lowering a reach-type forklift. In addition, the present invention also relates to a control method using the dual oil circuit control system for lifting and lowering a reach-type forklift. Background Art

[0002] Forklifts are widely used in the field of transportation and transshipment. The lifting system is an important working part of the forklift, including the front hydraulic cylinder and the side hydraulic cylinder, which are used to drive the lifting of the mast and forks.

[0003] In the prior art, the lifting and lowering oil circuits share the same oil circuit, and the front hydraulic cylinder and the side hydraulic cylinder are connected in series. Generally, the front hydraulic cylinder is lifted first, and then the side hydraulic cylinder. The speed of the front hydraulic cylinder is slower than that of the side hydraulic cylinder, and the lifting time is long, which affects the work efficiency. Furthermore, the pressures of the two hydraulic cylinders are different during lifting, and impact will occur when changing cylinders. At the same time, the lifting and changing cylinder impact and the top buffering adopt the speed reduction buffer. After reaching the top, the oil circuit will overflow together, causing the oil to do useless work and increase the heat. The high-speed descent causes the oil to heat up quickly. The increase in oil temperature increases the internal leakage and reduces the efficiency of the hydraulic system.

[0004] Therefore, how to provide a stable and efficient dual-oil circuit control system for the lifting of a reach forklift with two hydraulic cylinders respectively controlled is a technical problem that technical personnel in this field currently need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a dual oil circuit control system for lifting a reach-type forklift, in which the front hydraulic cylinder and the side hydraulic cylinder are connected in parallel and are respectively controlled by two proportional control valve groups, and the valve opening is controlled by detecting pressure and temperature, thereby improving control accuracy and controllability, improving overall machine efficiency, and reducing system heating. Another purpose of the present invention is to provide a control method including the dual oil circuit control system for lifting a reach-type forklift.

[0006] In order to solve the above technical problems, the present invention provides a dual oil circuit control system for lifting a forward-moving forklift, comprising an oil pump, an oil tank, a front hydraulic cylinder and a side hydraulic cylinder, comprising a front proportional control valve group and a side proportional control valve group connected in parallel, the oil inlet and oil return port of the front proportional control valve group and the side proportional control valve group are respectively connected to the oil pump and the oil tank, the working oil port of the front proportional control valve group is connected to the rodless chamber of the front hydraulic cylinder, and the working oil port of the side proportional control valve group is connected to the rodless chamber of the side hydraulic cylinder, and also comprises an altimeter, a front pressure sensor, a side pressure sensor and a temperature sensor which are communicatively connected to a controller, the altimeter is used to detect the lifting height, the front pressure sensor is used to detect the pressure of the rodless chamber of the front hydraulic cylinder, the side pressure sensor is used to detect the pressure of the rodless chamber of the side hydraulic cylinder, and the temperature sensor is used to detect the temperature of the hydraulic oil, and the controller controls the opening of the front proportional control valve group and the side proportional control valve group according to the height detection result, the pressure detection result and the temperature detection result.

[0007] Preferably, the front proportional control valve group includes a front lifting proportional control valve and a front lowering proportional control valve in parallel, the oil inlet and the working oil port of the front lifting proportional control valve are respectively connected to the oil pump and the rodless chamber of the front hydraulic cylinder, the oil return port and the working oil port of the front lowering proportional control valve are respectively connected to the oil tank and the rodless chamber of the front hydraulic cylinder, and the side proportional control valve group includes a side lifting proportional control valve and a side lowering proportional control valve in parallel, the oil inlet and the working oil port of the side lifting proportional control valve are respectively connected to the oil pump and the rodless chamber of the side hydraulic cylinder, and the oil return port and the working oil port of the side lowering proportional control valve are respectively connected to the oil tank and the rodless chamber of the side hydraulic cylinder.

[0008] Preferably, the oil inlet of the front lifting proportional control valve and the oil inlet of the side lifting proportional control valve are both provided with a one-way valve.

[0009] Preferably, the oil return port of the front descent proportional control valve and the oil return port of the side descent proportional control valve are both provided with a hydraulically controlled flow regulating valve.

[0010] Preferably, the front lifting proportional control valve, the front lowering proportional control valve, the side lifting proportional control valve and the side lowering proportional control valve are all electrically controlled proportional regulating valves, and the controller is communicatively connected to and controls each of the electrically controlled proportional regulating valves.

[0011] Preferably, a heat dissipation mechanism is installed on the oil tank, and the heat dissipation mechanism is communicatively connected to the controller, and the controller controls the power of the heat dissipation mechanism according to the temperature detection result.

[0012] The present invention provides a control method for a reach forklift lifting dual oil circuit control system, which is used to control any one of the reach forklift lifting dual oil circuit control systems described above, comprising the steps of:

[0013] When lifting, it receives the lifting signal and detects the lifting height;

[0014] The opening of the front lifting proportional control valve is controlled to gradually increase, and after the front hydraulic cylinder is extended to a first predetermined height, the opening of the front lifting proportional control valve is controlled to gradually decrease to zero;

[0015] After the front hydraulic cylinder extends to the first predetermined height, the opening of the side lifting proportional control valve is gradually increased, and after the side hydraulic cylinder extends to the second predetermined height, the opening of the side lifting proportional control valve is gradually reduced to zero;

[0016] When descending, it receives the descending signal and detects the lifting height;

[0017] The opening of the front descending proportional control valve is controlled to gradually increase, and after the front hydraulic cylinder is retracted to the third predetermined height, the opening of the front descending proportional control valve is controlled to gradually decrease to zero;

[0018] The opening of the side descending proportional control valve is controlled to gradually increase. After the side hydraulic cylinder retracts to the fourth predetermined height, the opening of the side descending proportional control valve is controlled to gradually decrease to zero, so that the side hydraulic cylinder descends to the bottom first.

[0019] Preferably, the first predetermined height is the maximum height of the front hydraulic cylinder minus the deceleration distance, the second predetermined height is the maximum height of the side hydraulic cylinder minus the deceleration distance, and the third predetermined height is equal to the fourth predetermined height.

[0020] Preferably, the receiving of the lifting signal and the receiving of the descending signal include the following steps:

[0021] Acquire the front pressure of the rodless chamber of the front hydraulic cylinder and the side pressure of the rodless chamber of the side hydraulic cylinder;

[0022] If the front pressure is less than or equal to the front preset pressure, and the side pressure is less than or equal to the side preset pressure, it means that the system is unloaded, and the front lifting proportional control valve, the front lowering proportional control valve, the side lifting proportional control valve and the side lowering proportional control valve are opened and closed with a no-load slope;

[0023] If the front pressure is greater than the front preset pressure and the side pressure is greater than the side preset pressure, it indicates that the system is overloaded, and the front lifting proportional control valve, the front lowering proportional control valve, the side lifting proportional control valve and the side lowering proportional control valve are opened and closed at a heavy load slope;

[0024] The no-load slope is greater than the heavy-load slope.

[0025] Preferably, the receiving of the lifting signal and the receiving of the descending signal include the following steps:

[0026] Acquiring a real-time temperature of the hydraulic oil in the oil tank, wherein the real-time temperature is compared with a first predetermined temperature and a second predetermined temperature, and the first predetermined temperature is less than the second predetermined temperature;

[0027] If the real-time temperature is lower than the first predetermined temperature, each valve is controlled to operate at a normal opening;

[0028] If the real-time temperature is greater than the first predetermined temperature and less than the second predetermined temperature, the heat dissipation mechanism is controlled to start, and each valve is controlled to operate at a normal opening;

[0029] If the real-time temperature is greater than the second predetermined temperature, the heat dissipation mechanism is controlled to start, and each valve is controlled to operate at a high-temperature opening, where the high-temperature opening is the normal opening multiplied by a reduction coefficient, and the reduction coefficient is less than one.

[0030] The present invention provides a dual-oil-circuit control system for lifting a forward-reaching forklift, comprising an oil pump, an oil tank, a front hydraulic cylinder and a side hydraulic cylinder, comprising a front proportional control valve group and a side proportional control valve group connected in parallel, the oil inlet and oil return port of the front proportional control valve group and the side proportional control valve group are respectively connected to the oil pump and the oil tank, the working oil port of the front proportional control valve group is connected to the rodless cavity of the front hydraulic cylinder, the working oil port of the side proportional control valve group is connected to the rodless cavity of the side hydraulic cylinder, and also comprises an altimeter, a front pressure sensor, a side pressure sensor and a temperature sensor which are communicatively connected to a controller, the altimeter is used for detecting the lifting height, the front pressure sensor is used for detecting the pressure of the rodless cavity of the front hydraulic cylinder, the side pressure sensor is used for detecting the pressure of the rodless cavity of the side hydraulic cylinder, and the temperature sensor is used for detecting the temperature of the hydraulic oil, and the controller controls the opening of the front proportional control valve group and the side proportional control valve group according to the height detection result, the pressure detection result and the temperature detection result.

[0031] The front hydraulic cylinder and the side hydraulic cylinder are connected in parallel and controlled separately by two proportional control valve groups. The system is changed to a dual oil circuit. The valve opening is controlled by detecting pressure and temperature to improve control accuracy and controllability. The dual oil circuit lifting is used to improve the cylinder change balance and efficiency, and the descending speed and the bottoming efficiency of the side hydraulic cylinder are increased to improve the efficiency of the whole machine. The buffering method is changed to avoid overflow after reaching the top, reduce useless work of oil, and reduce system heat.

[0032] The present invention also provides a control method using the above-mentioned dual oil circuit control system for lifting and lowering a reach forklift. Since the above-mentioned dual oil circuit control system for lifting and lowering a reach forklift has the above-mentioned technical effects, the above-mentioned control method should also have the same technical effects and will not be introduced in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a hydraulic principle diagram of a specific embodiment of a dual oil circuit control system for lifting a reach forklift provided by the present invention;

[0034] FIG. 2 is a control principle diagram of a specific implementation of a dual oil circuit control system for lifting a reach forklift provided by the present invention.

[0035] Among them, there are oil pump 1, oil tank 2, front hydraulic cylinder 3, side hydraulic cylinder 4, controller 5, front pressure sensor 6, side pressure sensor 7, temperature sensor 8, front lifting proportional control valve 9, front lowering proportional control valve 10, side lifting proportional control valve 11, side lowering proportional control valve 12, one-way valve 13, hydraulically controlled flow regulating valve 14, safety valve 15, heat dissipation mechanism 16, display 17, lifting thumb switch 18, lowering thumb switch 19, side cylinder pull wire sensor 20, and front cylinder pull wire sensor 21. DETAILED DESCRIPTION

[0036] The core of the present invention is to provide a dual oil circuit control system for lifting a reach-type forklift, in which the front hydraulic cylinder and the side hydraulic cylinder are connected in parallel and are respectively controlled by two proportional control valve groups, and the valve opening is controlled by detecting pressure and temperature, thereby improving control accuracy and controllability, improving overall machine efficiency, and reducing system heating. Another core of the present invention is to provide a control method including the dual oil circuit control system for lifting a reach-type forklift.

[0037] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0038] Please refer to Figures 1 and 2. Figure 1 is a hydraulic principle diagram of a specific implementation of the dual oil circuit control system for lifting and lowering a reach forklift provided by the present invention; Figure 2 is a control principle diagram of a specific implementation of the dual oil circuit control system for lifting and lowering a reach forklift provided by the present invention.

[0039] A specific embodiment of the present invention provides a dual oil circuit control system for lifting a reach forklift, including an oil pump 1, an oil tank 2, a front hydraulic cylinder 3 and a side hydraulic cylinder 4. The oil tank 2 provides hydraulic oil, and the oil pump 1 provides sufficient pressure to output the hydraulic oil. The front hydraulic cylinder 3 is used to drive the lifting of the fork, and the two parallel side hydraulic cylinders 4 are used to drive the lifting of the door frame. In order to control the actions of the front hydraulic cylinder 3 and the side hydraulic cylinder 4, a parallel front proportional control valve group and a side proportional control valve group are set, wherein the front proportional control valve group has an oil inlet, an oil return port and a working oil port, the oil inlet and the oil return port are respectively connected to the oil pump 1 and the oil tank 2, and the working oil port is connected to the rodless chamber of the front hydraulic cylinder 3. When lifting, the oil inlet of the front proportional control valve group is connected to the working oil port, and the high-pressure oil output by the oil pump 1 enters the rodless chamber of the front hydraulic cylinder 3, driving the front hydraulic cylinder 3 to extend, and the fork is lifted, and the extension speed of the front hydraulic cylinder 3 is adjusted by controlling the opening of the front proportional control valve group. When descending, the oil return port of the front proportional control valve group is connected to the working oil port, and the hydraulic oil in the rodless chamber of the front hydraulic cylinder 3 flows back to the oil tank 2, the front hydraulic cylinder 3 retracts, and the fork descends, and the retraction speed of the front hydraulic cylinder 3 is adjusted by controlling the opening of the front proportional control valve group. The side proportional control valve group has an oil inlet, an oil return port and a working oil port. The oil inlet and the oil return port are respectively connected to the oil pump 1 and the oil tank 2. The working oil port is connected to the rodless chamber of the side hydraulic cylinder 4. When lifting, the oil inlet of the side proportional control valve group is connected to the working oil port, and the high-pressure oil output by the oil pump 1 enters the rodless chamber of the side hydraulic cylinder 4, driving the side hydraulic cylinder 4 to extend, and the gantry is lifted. By controlling the opening of the side proportional control valve group, the extension speed of the side hydraulic cylinder 4 is adjusted. When descending, the oil return port of the side proportional control valve group is connected to the working oil port, and the hydraulic oil in the rodless chamber of the side hydraulic cylinder 4 flows back to the oil tank 2, the side hydraulic cylinder 4 retracts, and the gantry descends. By controlling the opening of the side proportional control valve group, the retraction speed of the side hydraulic cylinder 4 is adjusted.

[0040] Through the above method, the front hydraulic cylinder 3 and the side hydraulic cylinder 4 are connected in parallel and controlled separately by two proportional control valve groups, the system is changed to a dual oil circuit, the correlation between the two hydraulic cylinders is reduced, and the openings of the two proportional control valve groups are adjusted during lifting to make the lifting speed of the front hydraulic cylinder 3 equal to the lifting speed of the side hydraulic cylinder 4, thereby improving the efficiency of the whole machine. Separate control can also avoid overflow after reaching the top, reduce useless work of oil, reduce system heat generation, and ensure that the side hydraulic cylinder 4 reaches the bottom first during descending to ensure equipment reliability.

[0041] Furthermore, it also includes an altimeter, a front pressure sensor 6, a side pressure sensor 7 and a temperature sensor 8 which are communicatively connected to the controller 5. The altimeter is used to detect the lifting height, the front pressure sensor 6 is used to detect the rodless cavity pressure of the front hydraulic cylinder 3, the side pressure sensor 7 is used to detect the rodless cavity pressure of the side hydraulic cylinder 4, and the temperature sensor 8 is used to detect the temperature of the hydraulic oil. The controller 5 controls the opening of the front proportional control valve group and the side proportional control valve group according to the height detection results, the pressure detection results and the temperature detection results.

[0042] Through height detection, the opening is reduced in advance to slow down, improve cylinder change efficiency, prevent sudden changes in speed, and avoid useless work. According to pressure detection, the load condition is judged, and the opening and closing slopes are adjusted to avoid gantry shaking. According to temperature detection, the system oil temperature is judged, the opening is reduced, the speed is reduced, and the temperature is reduced to improve equipment reliability.

[0043] Specifically, the front proportional control valve group includes a front lifting proportional control valve 9 and a front lowering proportional control valve 10 in parallel, the oil inlet and the working oil port of the front lifting proportional control valve 9 are respectively connected to the oil pump 1 and the rodless chamber of the front hydraulic cylinder 3, the oil return port and the working oil port of the front lowering proportional control valve 10 are respectively connected to the oil tank 2 and the rodless chamber of the front hydraulic cylinder 3, and the side proportional control valve group includes a side lifting proportional control valve 11 and a side lowering proportional control valve 12 in parallel, the oil inlet and the working oil port of the side lifting proportional control valve 11 are respectively connected to the oil pump 1 and the rodless chamber of the side hydraulic cylinder 4, and the oil return port and the working oil port of the side lowering proportional control valve 12 are respectively connected to the oil tank 2 and the rodless chamber of the side hydraulic cylinder 4. That is, the four proportional control valves are all connected in parallel, two of which are connected to the oil pump 1, the oil tank 2 and the front hydraulic cylinder 3 to control the lifting and lowering of the front hydraulic cylinder 3, and both can realize the opening adjustment. The other two are connected to the oil pump 1, the oil tank 2 and the side hydraulic cylinder 4 to control the lifting and lowering of the side hydraulic cylinder 4, and both can realize the opening adjustment. During lifting, the front descent proportional control valve 10 and the side descent proportional control valve 12 maintain zero opening and are in an isolated state. During descending, the front lifting proportional control valve 9 and the side lifting proportional control valve 11 maintain zero opening and are in an isolated state.

[0044] Furthermore, the oil inlet of the front lifting proportional control valve 9 and the oil inlet of the side lifting proportional control valve 11 are both provided with a one-way valve 13. Only the hydraulic oil output by the oil pump 1 is allowed to enter the corresponding proportional control valve to prevent backflow. The return oil port of the front descent proportional control valve 10 and the return oil port of the side descent proportional control valve 12 are both provided with a hydraulically controlled flow regulating valve 14. The two hydraulically controlled ports of the hydraulically controlled flow regulating valve 14 are respectively connected to the working oil port and the return oil port of the corresponding descent proportional control valve, and cooperate with the auxiliary pressure supplement component. When the descent speed is too fast, the working oil port pressure of the descent proportional control valve is much greater than the return oil port pressure. At this time, the hydraulically controlled flow regulating valve 14 reduces the opening, slows down the descent speed, and improves safety. Among them, the front lifting proportional control valve 9, the front lowering proportional control valve 10, the side lifting proportional control valve 11 and the side lowering proportional control valve 12 are all electrically controlled proportional regulating valves, the controller 5 communicates and controls each electrically controlled proportional regulating valve, the electrical signal sent by the controller 5 controls the opening of each proportional control valve, and a safety valve 15 can also be set to improve the safety of the system. Of course, the type of valve can also be selected according to the situation, all within the protection scope of the present invention.

[0045] In another specific embodiment, the front proportional control valve group includes a proportional regulating valve and two switch valves, the oil pump 1 is connected to one switch valve, the oil tank 2 is connected to the other switch valve, the two switch valves are simultaneously connected to a working oil port of the proportional regulating valve, and the other working oil port of the proportional regulating valve is connected to the rodless chamber of the front hydraulic cylinder 3. The lifting and lowering of the front hydraulic cylinder 3 is realized by opening and closing the two switch valves, and the structure of the side proportional control valve group is similar.

[0046] On the basis of the dual oil circuit control system for lifting of a reach forklift provided in the above specific embodiments, a heat dissipation mechanism 16 is installed on the oil tank 2, and the heat dissipation mechanism 16 is communicatively connected to the controller 5, and the controller 5 controls the power of the heat dissipation mechanism 16 according to the temperature detection result. Specifically, the heat dissipation mechanism 16 can be a fan heat dissipation, or a liquid cooling heat dissipation or other methods.

[0047] In the dual oil circuit control system for lifting of a reach forklift provided in the specific embodiment of the present invention, in order to facilitate control, a display 17, a lifting thumb switch 18, and a lowering thumb switch 19 are matched and arranged, which are used to display data information, control lifting, and control lowering, respectively. The lifting speed switch signal of the lifting thumb switch 18 has a voltage change of 2.5 to 5V, and the corresponding speed of the motor driving the oil pump 1 is 0 to n max , the descending speed switch signal of the descending thumb switch 19, the voltage changes from 0 to 2.5V, and the corresponding valve opening is 0 to G max .

[0048] Furthermore, the front pressure sensor 6 is installed at the bottom of the front hydraulic cylinder 3, the side pressure sensor 7 is installed at the bottom of the side hydraulic cylinder 4, and the altimeter uses an absolute encoder to detect the height of the mast, including the height of the front hydraulic cylinder 3 and the side hydraulic cylinder 4, specifically including the side cylinder wire sensor 20 and the front cylinder wire sensor 21. The temperature sensor is installed on the oil tank 2.

[0049] The specific embodiment of the present invention also provides a control method for a reach forklift lifting dual oil circuit control system, which is used to control the reach forklift lifting dual oil circuit control system provided in the above specific embodiment, comprising the steps of:

[0050] During lifting, a lifting signal is input through the lifting thumb switch 18, which is received by the controller 5, and the lifting height is detected in real time.

[0051] The opening of the front lift proportional control valve 9 is controlled to gradually increase, and the high-pressure oil output by the oil pump 1 enters the rodless chamber of the front hydraulic cylinder 3. The extension speed of the front hydraulic cylinder 3 gradually increases. When the front hydraulic cylinder 3 is extended to the first predetermined height, it indicates that the front hydraulic cylinder 3 is about to reach the highest position. At this time, the opening of the front lift proportional control valve 9 is controlled to gradually decrease to zero, so that the extension speed of the front hydraulic cylinder 3 gradually decreases and finally stops extending.

[0052] At the same time, after the front hydraulic cylinder 3 extends to the first predetermined height, that is, during the process of the opening of the front lifting proportional control valve 9 gradually decreasing, the opening of the side lifting proportional control valve 11 is controlled to gradually increase, and the high-pressure oil output by the oil pump 1 enters the rodless chamber of the side hydraulic cylinder 4, and the extension speed of the side hydraulic cylinder 4 gradually increases. When the side hydraulic cylinder 4 extends to the second predetermined height, it means that the side hydraulic cylinder 4 is about to reach the highest position. At this time, the opening of the side lifting proportional control valve 11 is controlled to gradually decrease to zero, so that the extension speed of the side hydraulic cylinder 4 gradually decreases and finally stops extending. Through the above method, when the front hydraulic cylinder 3 is about to reach the stop position, it starts to decelerate in advance, and at the same time, the side hydraulic cylinder 4 starts to extend slowly, which reduces the impact of cylinder change, improves the efficiency of cylinder change, avoids the front hydraulic cylinder 3 from generating useless work after reaching the top, and improves the efficiency of the whole machine. Further, when the side hydraulic oil 4 is about to reach the stop position, it starts to decelerate in advance, and the buffering is softer to avoid sudden changes in the motor speed. And it can adjust the opening according to the situation, and then adjust the lifting speed, so that the lifting speed of the front hydraulic cylinder 3 and the side hydraulic cylinder 4 can be the same.

[0053] When descending, a descending signal is input through the descending thumb switch 19, which is received by the controller 5, and the lifting height is detected in real time.

[0054] The opening of the front descent proportional control valve 10 is controlled to gradually increase, and the hydraulic oil in the rodless chamber of the front hydraulic cylinder 3 flows back to the oil tank 2. The retraction speed of the front hydraulic cylinder 3 gradually increases. When the front hydraulic cylinder 3 is retracted to the third predetermined height, it indicates that the front hydraulic cylinder 3 is about to reach the bottom. At this time, the opening of the front descent proportional control valve 10 is controlled to gradually decrease to zero, so that the retraction speed of the front hydraulic cylinder 3 gradually decreases and finally stops retracting.

[0055] At the same time, the opening of the side descent proportional control valve 12 is controlled to gradually increase, the hydraulic oil in the rodless chamber of the side hydraulic cylinder 4 flows back to the oil tank 2, and the retraction speed of the side hydraulic cylinder 4 gradually increases. After the side hydraulic cylinder 4 is retracted to the fourth predetermined height, it indicates that the side hydraulic cylinder 4 is about to reach the bottom. At this time, the opening of the side descent proportional control valve 12 is controlled to gradually decrease to zero, so that the retraction speed of the side hydraulic cylinder 4 gradually decreases and finally stops retracting, and the descending speed of the two cylinders is controlled to make the side hydraulic cylinder 4 descend to the bottom first to avoid interference and collision.

[0056] Specifically, the first predetermined height is the maximum height of the front hydraulic cylinder 3 minus the deceleration distance, the second predetermined height is the maximum height of the side hydraulic cylinder 4 minus the deceleration distance, and the third predetermined height is equal to the fourth predetermined height, which can be 600 mm.

[0057] Preferably, after receiving the lifting signal and receiving the descending signal, the method comprises the following steps:

[0058] Obtain the front pressure of the rodless chamber of the front hydraulic cylinder 3 and the side pressure of the rodless chamber of the side hydraulic cylinder 4; determine the equipment load condition by the two pressure values. Specifically, the front predetermined pressure is 0.2MPa and the side predetermined pressure is 0.6MPa.

[0059] If the front pressure is less than or equal to the front preset pressure, and the side pressure is less than or equal to the side preset pressure, it means that the system is unloaded, and the front lifting proportional control valve 9, the front lowering proportional control valve 10, the side lifting proportional control valve 11 and the side lowering proportional control valve 12 are opened and closed with the no-load slope; if the front pressure is greater than the front preset pressure, and the side pressure is greater than the side preset pressure, it means that the system is overloaded, and the front lifting proportional control valve 9, the front lowering proportional control valve 10, the side lifting proportional control valve 11 and the side lowering proportional control valve 12 are opened and closed with the heavy load slope; wherein, the no-load slope is greater than the heavy load slope. According to the opening slope of the no-load or heavy-load control valve, when unloaded, the opening slope is large, the control is timely and accurate, and when heavily loaded, the opening slope is small to prevent the gantry from shaking due to a rapid increase in speed. According to the closing slope of the no-load or heavy-load control valve, when unloaded, the closing slope is large, the control is timely and accurate, and when heavily loaded, the closing slope is small to prevent the gantry from shaking due to a rapid increase in speed.

[0060] On the basis of the control method of the dual oil circuit control system for lifting of the reach forklift provided in the above specific embodiments, temperature detection is added, and after receiving the lifting signal and the lowering signal, the following steps are included:

[0061] Acquire the real-time temperature of the hydraulic oil in the oil tank 2, compare the real-time temperature with the first predetermined temperature and the second predetermined temperature, and the first predetermined temperature is lower than the second predetermined temperature;

[0062] If the real-time temperature is lower than the first predetermined temperature, each valve is controlled to operate at a normal opening;

[0063] If the real-time temperature is greater than the first predetermined temperature and less than the second predetermined temperature, the heat dissipation mechanism 16 is controlled to start, and each valve is controlled to operate at a normal opening;

[0064] If the real-time temperature is greater than the second predetermined temperature, the heat dissipation mechanism 16 is controlled to start, and each valve is controlled to operate at a high-temperature opening, which is the normal opening multiplied by the reduction coefficient, and the reduction coefficient is less than one, that is, under high temperature conditions, the opening of each valve is reduced, the operating speed is reduced, and the temperature is reduced. In this embodiment, the reduction coefficient is 0.6.

[0065] The values ​​of various parameters can be adjusted according to the situation, all within the protection scope of the present invention.

[0066] The above is a detailed introduction to the reach forklift lifting dual oil circuit control system and control method provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A control method for a dual oil circuit control system for a reach forklift, used to control a dual oil circuit control system for a reach forklift, characterized in that: The dual oil circuit control system for lifting a forward-reaching forklift comprises an oil pump (1), an oil tank (2), a front hydraulic cylinder (3) and a side hydraulic cylinder (4), and is characterized in that it comprises a front proportional control valve group and a side proportional control valve group connected in parallel, wherein the oil inlet and oil return ports of the front proportional control valve group and the side proportional control valve group are respectively connected to the oil pump (1) and the oil tank (2), the working oil port of the front proportional control valve group is connected to the rodless chamber of the front hydraulic cylinder (3), and the working oil port of the side proportional control valve group is connected to the rodless chamber of the side hydraulic cylinder (4), and further comprises a communication connection control The controller (5) comprises an altimeter, a front pressure sensor (6), a side pressure sensor (7) and a temperature sensor (8), wherein the altimeter is used to detect the lifting height, the front pressure sensor (6) is used to detect the rodless chamber pressure of the front hydraulic cylinder (3), the side pressure sensor (7) is used to detect the rodless chamber pressure of the side hydraulic cylinder (4), and the temperature sensor (8) is used to detect the temperature of the hydraulic oil, and the controller (5) controls the opening of the front proportional control valve group and the side proportional control valve group according to the height detection result, the pressure detection result and the temperature detection result; Includes steps: When lifting, it receives the lifting signal and detects the lifting height; The opening of the front lifting proportional control valve (9) is controlled to gradually increase, and after the front hydraulic cylinder (3) is extended to a first predetermined height, the opening of the front lifting proportional control valve (9) is controlled to gradually decrease to zero; After the front hydraulic cylinder (3) is extended to the first predetermined height, the opening of the side lifting proportional control valve (11) is controlled to gradually increase, and after the side hydraulic cylinder (4) is extended to the second predetermined height, the opening of the side lifting proportional control valve (11) is controlled to gradually decrease to zero; When descending, it receives the descending signal and detects the lifting height; The opening of the front descending proportional control valve (10) is controlled to gradually increase, and after the front hydraulic cylinder (3) is retracted to a third predetermined height, the opening of the front descending proportional control valve (10) is controlled to gradually decrease to zero; The opening of the side descending proportional control valve (12) is controlled to gradually increase, and after the side hydraulic cylinder (4) is retracted to a fourth predetermined height, the opening of the side descending proportional control valve (12) is controlled to gradually decrease to zero, so that the side hydraulic cylinder (4) descends to the bottom first.

2. The control method of the dual oil circuit control system for lifting of a reach forklift according to claim 1 is characterized in that: The first predetermined height is the maximum height of the front hydraulic cylinder (3) minus the deceleration distance, the second predetermined height is the maximum height of the side hydraulic cylinder (4) minus the deceleration distance, and the third predetermined height is equal to the fourth predetermined height.

3. The control method of the dual oil circuit control system for lifting of a reach forklift according to claim 2 is characterized in that: The receiving of the lifting signal and the receiving of the descending signal include the following steps: Obtaining the front pressure of the rodless chamber of the front hydraulic cylinder (3) and the side pressure of the rodless chamber of the side hydraulic cylinder (4); If the front pressure is less than or equal to the front preset pressure, and the side pressure is less than or equal to the side preset pressure, it indicates that the system is unloaded, and the front lifting proportional control valve (9), the front lowering proportional control valve (10), the side lifting proportional control valve (11), and the side lowering proportional control valve (12) are opened and closed at a no-load slope; If the front pressure is greater than the front preset pressure and the side pressure is greater than the side preset pressure, it indicates that the system is overloaded, and the front lifting proportional control valve (9), the front lowering proportional control valve (10), the side lifting proportional control valve (11) and the side lowering proportional control valve (12) are opened and closed at a heavy load slope; The no-load slope is greater than the heavy-load slope.

4. The control method of the dual oil circuit control system for lifting of a reach forklift according to any one of claims 1 to 3, characterized in that: The receiving of the lifting signal and the receiving of the descending signal include the following steps: Acquiring a real-time temperature of the hydraulic oil in the oil tank (2), wherein the real-time temperature is compared with a first predetermined temperature and a second predetermined temperature, wherein the first predetermined temperature is lower than the second predetermined temperature; If the real-time temperature is lower than the first predetermined temperature, each valve is controlled to operate at a normal opening; If the real-time temperature is greater than the first predetermined temperature and less than the second predetermined temperature, the heat dissipation mechanism (16) is controlled to start, and each valve is controlled to operate at a normal opening; If the real-time temperature is greater than the second predetermined temperature, the heat dissipation mechanism (16) is controlled to start, and each valve is controlled to operate at a high-temperature opening, wherein the high-temperature opening is the normal opening multiplied by a reduction coefficient, and the reduction coefficient is less than one.

5. The control method of the dual oil circuit control system for lifting of a reach forklift according to claim 1, characterized in that: The front proportional control valve group comprises a front lifting proportional control valve (9) and a front lowering proportional control valve (10) connected in parallel, the oil inlet and the working oil port of the front lifting proportional control valve (9) are respectively connected to the oil pump (1) and the rodless chamber of the front hydraulic cylinder (3), the oil return port and the working oil port of the front lowering proportional control valve (10) are respectively connected to the oil tank (2) and the rodless chamber of the front hydraulic cylinder (3), the side proportional control valve group comprises a side lifting proportional control valve (11) and a side lowering proportional control valve (12) connected in parallel, the oil inlet and the working oil port of the side lifting proportional control valve (11) are respectively connected to the oil pump (1) and the rodless chamber of the side hydraulic cylinder (4), the oil return port and the working oil port of the side lowering proportional control valve (12) are respectively connected to the oil tank (2) and the rodless chamber of the side hydraulic cylinder (4).

6. The control method of the dual oil circuit control system for lifting of a reach forklift according to claim 5, characterized in that: The oil inlet of the front lifting proportional control valve (9) and the oil inlet of the side lifting proportional control valve (11) are both provided with a one-way valve (13).

7. The control method of the dual oil circuit control system for lifting of a reach forklift according to claim 6, characterized in that: The oil return port of the front descent proportional control valve (10) and the oil return port of the side descent proportional control valve (12) are both provided with a hydraulically controlled flow regulating valve (14).

8. The control method of the dual oil circuit control system for lifting of a reach forklift according to claim 7, characterized in that: The front lifting proportional control valve (9), the front lowering proportional control valve (10), the side lifting proportional control valve (11) and the side lowering proportional control valve (12) are all electrically controlled proportional regulating valves, and the controller is communicatively connected to and controls each of the electrically controlled proportional regulating valves.

9. The control method of the dual oil circuit control system for lifting of a reach forklift according to claim 1, characterized in that: A heat dissipation mechanism (16) is installed on the oil tank (2), the heat dissipation mechanism (16) is communicatively connected to the controller (5), and the controller (5) controls the power of the heat dissipation mechanism (16) according to a temperature detection result.

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