A forklift mast lifting and lowering buffer device and buffer control method

Abstract

The invention discloses a forklift gantry lifting and lowering buffer device, comprising a slidingly connected outer gantry, an inner gantry and a lifting oil cylinder for pushing the gantry to move, characterized in that the lifting oil cylinder is connected to an oil supply part and a lifting control part; the oil supply part comprises a hydraulic oil tank, the hydraulic oil tank is connected to a gear pump, the gear pump is connected to an oil pump motor, the oil outlet of the gear pump is connected to a lifting solenoid valve, the oil outlet of the lifting solenoid valve is connected to the lifting oil cylinder, and the oil return port of the lifting oil cylinder is connected to the hydraulic oil tank through the lowering solenoid valve; the application adopts a lifting height sensor to detect the gantry position in real time, different gantry positions correspond to different oil pump motor speeds and different solenoid valve openings, so as to achieve gantry lifting into place buffering and reduce the gantry lifting into place impact; the lifting height sensor is adopted to detect the gantry position in real time, different gantry positions correspond to different solenoid valve openings, so as to achieve gantry lowering into place buffering and reduce the gantry lowering into place impact.

Description

Technical Field

[0001] The invention relates to the technical field of forklift masts, and in particular to a forklift mast lifting and lowering buffer device and a buffer control method. Background Art

[0002] A forklift is a commonly used industrial vehicle. A hydrogen fuel forklift is a new type of energy forklift with excellent development prospects. A hydrogen fuel forklift mainly works through a fork, which is installed on a gantry and drives the fork up and down by sliding the gantry up and down. Moreover, current forklift forks use a hydraulic lifting system to drive the gantry and fork to lift and lower. The existing hydrogen fuel forklift gantry lifting and lowering system only uses an electric motor to drive the oil pump, and then drives the gantry to move through a hydraulic system. However, the working process of the hydraulic system is relatively linear, and there is no lifting buffer system and a lowering buffer system. There is a large impact when lifting and lowering into place, which has a large impact on the gantry and is easy to damage the gantry. It also causes the fork to be unstable, and there may be a risk of cargo falling. Summary of the invention

[0003] The object of the present invention is to provide a forklift mast lifting and lowering buffer device and a buffer control method to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A forklift mast lifting and lowering buffer device comprises a slidingly connected outer mast, an inner mast and a lifting oil cylinder for pushing the mast to move, characterized in that the lifting oil cylinder is connected to an oil supply part and a lifting control part;

[0006] The oil supply unit includes a hydraulic oil tank, the hydraulic oil tank is connected to a gear pump, the gear pump is connected to an oil pump motor, the oil outlet of the gear pump is connected to a lifting solenoid valve, the oil outlet of the lifting solenoid valve is connected to the lifting cylinder, and the oil return port of the lifting cylinder is connected to the hydraulic oil tank through a descending solenoid valve;

[0007] The lifting control unit includes a valve controller, which is in signal communication with the lifting solenoid valve and the lowering solenoid valve. The valve controller is connected to a lifting height sensor and a switch unit, which includes a lowering switch, a lifting switch, and a potentiometer. The valve controller is connected to an oil pump motor controller, which is in signal communication with the oil pump motor.

[0008] As a further solution of the present invention: the oil outlet of the gear pump is connected to a pump outlet check valve, the oil outlet of the pump outlet check valve is communicated with a lifting solenoid valve, the oil outlet of the pump outlet check valve is connected to a relief valve, the relief valve is communicated with a hydraulic oil tank, and the oil outlet of the lifting solenoid valve is provided with a valve outlet check valve.

[0009] As a further solution of the present invention: the oil return port of the lifting solenoid valve is connected to the hydraulic oil tank through a manual unloading valve.

[0010] As a further solution of the present invention: the valve controller is connected to a fuel cell system, the fuel cell system includes a fuel cell power generation system, a lithium battery pack, and a FUC controller, the fuel cell power generation system is connected to a DC-DC converter, and the lithium battery pack is connected to the DC-DC converter.

[0011] As a further solution of the present invention: the lithium battery pack, FUC controller, and DC-DC converter are connected to the valve controller and the oil pump motor controller respectively.

[0012] A forklift mast lifting and lowering buffer control method, characterized in that it comprises the following steps:

[0013] S1. Determine whether the forklift is in the mast raising state or the mast lowering state according to the state of the lowering switch and the raising switch. If the forklift is in the mast raising state, execute step 2; if the forklift is in the mast lowering state, execute step 3.

[0014] S2, the valve controller detects the mast position H in real time according to the lifting height sensor. If H≤Hmax-L, it is in the normal lifting state, and normal lifting is sufficient. If H>Hmax-L, it is in the lifting buffer state. At this time, the valve sensor and the oil pump motor controller are used to control the oil pump motor speed and the outlet flow of the lifting solenoid valve to reduce the lifting speed;

[0015] S3, the valve controller detects the mast position H in real time according to the lifting height sensor. If H>L, it is in the normal descending state and descends normally. If H≤L, it is in the descending buffer state. At this time, the outlet flow of the solenoid valve is lowered through the valve sensor to reduce the descent speed.

[0016] Among them: H is the real-time height of the gantry, Hmax is the maximum lifting height of the gantry, L is the buffer height, and the value range of L is: 150mm<L<250mm.

[0017] As a further solution of the present invention: in S2 and S3, the valve controller transmits the mast position signal C1 to the oil pump motor controller through the CAN bus, and the oil pump motor controller controls the oil pump motor speed according to the mast position signal C1 and the potentiometer signal C4; the valve controller controls the current of the proportional electromagnet m2 of the lifting solenoid valve according to the mast position signal C1 and the potentiometer signal C4, controls the opening of the lifting solenoid valve, and controls the outlet flow of the lifting solenoid valve; the valve controller controls the current of the proportional electromagnet m1 of the lowering solenoid valve according to the mast position signal C1 and the potentiometer signal C4, controls the opening of the lowering solenoid valve, and controls the outlet flow of the lowering solenoid valve.

[0018] As a further solution of the present invention: the buffer height L is 200mm, in the normal lifting state, n=max((C4-2.5)*1200,500), Q1=(C4-2.5)*1.2*q; in the lifting buffer state, n=max((5-C1)*1200,300), Q1=(5-C1)*1.2*q; wherein: q is the displacement of the gear pump, n is the speed of the oil pump motor, Q1 is the outlet flow of the lifting battery valve, C1 is the mast position signal detected by the lifting height sensor, and C4 is the voltage signal of the potentiometer.

[0019] As a further solution of the present invention: the buffer height L is 200 mm, in the normal descending state, Q2 = (2.5-C4)*1.2*q; in the descending buffering state, Q2 = C1*1.2*q;

[0020] Among them: q is the displacement of the gear pump, Q2 is the outlet flow of the descending solenoid valve, C1 is the mast position signal detected by the lifting height sensor, and C4 is the output voltage signal of the potentiometer.

[0021] Compared with the prior art, the beneficial effects of the present invention are: the present application adopts a lifting height sensor to detect the gantry position in real time, and different gantry positions correspond to different oil pump motor speeds and different solenoid valve openings, so as to achieve gantry lifting into position buffering and reduce the impact of gantry lifting into position; a lifting height sensor is adopted to detect the gantry position in real time, and different gantry positions correspond to different solenoid valve openings, so as to achieve gantry lowering into position buffering and reduce the impact of gantry lowering into position. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the buffer system principle of this embodiment.

[0023] In the figure: 1-outer mast, 2-inner mast, 3-lifting cylinder, 4-lifting height sensor, 5-valve controller, 6-switch part, 7-lowering switch, 8-lifting switch, 9-potentiometer, 10-fuel cell system, 11-FCU controller, 12-DC-DC converter, 13-lithium battery pack, 14-fuel cell power generation system, 15-oil pump motor controller, 16-overflow valve, 17-oil pump motor, 18-gear pump, 19-hydraulic oil tank, 20-pump outlet check valve, 21-lifting solenoid valve, 22-valve outlet check valve, 23-lowering solenoid valve, 24-manual unloading valve. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1 In an embodiment of the present invention, a forklift mast lifting and lowering buffer device comprises an outer mast 1, an inner mast 2 and a lifting oil cylinder 3 for pushing the mast to move, an oil supply part and a lifting control part connected to the lifting oil cylinder 3;

[0026] The oil supply unit includes a hydraulic oil tank 19, which is connected to a gear pump 18. The oil outlet of the gear pump 18 is connected to a pump outlet check valve 20. The gear pump 18 is connected to an oil pump motor 17. The oil outlet of the gear pump 18 is connected to a lifting solenoid valve 21. The oil outlet of the pump outlet check valve 20 is connected to the lifting solenoid valve 21. The oil outlet of the lifting solenoid valve 21 is connected to the lifting cylinder 3. The oil outlet of the lifting solenoid valve 21 is provided with a valve outlet check valve 22. The oil outlet of the pump outlet check valve 20 is connected to a relief valve 16. The relief valve 16 is connected to the hydraulic oil tank 19. The oil return port of the lifting cylinder 3 is connected to the hydraulic oil tank 19 through a descending solenoid valve 23. The oil return port of the lifting solenoid valve 3 is connected to the hydraulic oil tank 19 through a manual unloading valve 24.

[0027] The lifting control unit includes a valve controller 5, which is connected to the lifting solenoid valve 21 and the lowering solenoid valve 23 by signal. The valve controller 5 is connected to a lifting height sensor 4 and a switch unit 6. The switch unit 6 includes a lowering switch 7, a lifting switch 8, and a potentiometer 9. The valve controller 5 is connected to an oil pump motor controller 15, which is connected to the oil pump motor 17 by signal.

[0028] Potentiometer 9 outputs voltage signal C4 (its variation range is: 0~5V). When switch part 6 is in the middle position, potentiometer 9 outputs voltage signal C4=2.5V. When switch part 6 is pushed forward (door frame descends), potentiometer 9 outputs voltage signal with variation range of 2.5~0V. When switch part 6 is pulled back (door frame rises), potentiometer 9 outputs voltage signal with variation range of 2.5~5V. Lifting switch 8 signal C3 is a switch signal, and its value is 0 or 1. When C3=1, it indicates that the lifting switch is closed and sends a door frame lifting request to the controller. When C3=0, it indicates that the lifting switch is disconnected. Lowering switch signal C2 is a switch signal, and its value is 0 or 1. When C2=1, it indicates that the lowering switch is closed and sends a door frame lowering request to the controller. When C2=0, it indicates that the lowering switch is disconnected.

[0029] The lifting height sensor 4 outputs a voltage signal C1 (its variation range is: 0~5V). The mast lifting height H is positively correlated with C1, and 5V corresponds to the maximum lifting height Hmax.

[0030] The valve controller 5 is connected to a fuel cell system 10, which includes a fuel cell power generation system 14, a lithium battery pack 13, and a FUC controller 11. The fuel cell power generation system 14 is connected to a DC-DC converter 12, and the lithium battery pack 13 is connected to the DC-DC converter 12. The lithium battery pack 13, the FUC controller 11, and the DC-DC converter 12 are connected to the valve controller 5 and the oil pump motor controller 15, respectively.

[0031] During use, when the mast needs to be lifted, the fuel cell system 10 supplies power to the oil pump motor 17 through the oil pump motor controller 15, and the oil pump motor 17 drives the gear pump 18 to rotate. The hydraulic oil output by the gear pump 18 passes through the pump outlet check valve 20, the lifting solenoid valve 21, and the valve outlet check valve 22 to the lifting cylinder 3, and the lifting cylinder 3 pushes the inner mast 2 to move upward in the outer mast 1 to achieve mast lifting. At this time, the valve controller 5 controls the valve core of the lifting solenoid valve 21 to be in the left position, and the valve core of the lowering solenoid valve 23 to be in the lower position.

[0032] When the mast needs to be lowered, under the action of gravity, the hydraulic oil of the lifting cylinder 3 returns to the hydraulic oil tank 19 through the lowering solenoid valve 23, and the lifting cylinder 3 pushes the inner mast 2 to move downward in the outer mast 1, so that the mast is lowered. At this time, the valve controller 5 controls the valve core of the lifting solenoid valve 21 to be in the right position, and the valve core of the lowering solenoid valve 23 to be in the upper position.

[0033] When manual unloading is required, when the gantry stops at a high position, the system loses power and the gantry needs to be lowered, open the manual unloading valve 24, and under the action of gravity, the hydraulic oil of the lifting cylinder 3 returns to the hydraulic oil tank 19 through the manual unloading valve 24, and the lifting cylinder 3 pushes the inner gantry 2 to move downward in the outer gantry 1, thereby realizing the descent of the gantry.

[0034] A forklift mast lifting and lowering buffer control method comprises the following steps:

[0035] S1. Determine whether the forklift is in the mast raising state or the mast lowering state according to the states of the lowering switch 7 and the raising switch 8. If the forklift is in the mast raising state, execute step 2; if the forklift is in the mast lowering state, execute step 3.

[0036] S2, the valve controller 5 detects the mast position H in real time according to the lifting height sensor 4. If H≤Hmax-L, it is in the normal lifting state, and normal lifting is sufficient. If H>Hmax-L, it is in the lifting buffer state. At this time, the valve sensor 5 and the oil pump motor controller 15 control the oil pump motor speed and the outlet flow of the lifting solenoid valve 21 to reduce the lifting speed;

[0037] If H≤Hmax-L, it is in the normal lifting state, L is the buffer height, and the value range of L is: 150mm<L<250mm. At this time, it is normal lifting. In this embodiment, the buffer height L is 200mm. In the normal lifting state, the speed of the oil pump motor 17 is related to the output signal C4 of the potentiometer 9, and the speed of the oil pump motor n=max((C4-2.5)*1200,500), the outlet flow of the lifting solenoid valve 21 is related to the output signal C4 of the potentiometer 9, and the outlet flow of the lifting solenoid valve Q=(C4-2.5)*1.2*q;

[0038] If H>Hmax-L, it is in the lifting buffer state, the speed of the oil pump motor 17 is related to the output signal C1 of the lifting height sensor 4, the speed of the oil pump motor n=max((5-C1)*1200,300), the outlet flow of the lifting solenoid valve 21 is related to the output signal C1 of the lifting height sensor 4, and the outlet flow of the lifting solenoid valve Q=(5-C1)*1.2*q;

[0039] Among them: H is the real-time height of the gantry, and Hmax is the maximum lifting height of the gantry.

[0040] S3, the valve controller 5 detects the mast position H in real time according to the lifting height sensor 4, and the valve controller 5 controls the current of the proportional electromagnet m1 of the descending solenoid valve 23 according to the mast position signal C1 and the potentiometer signal C4, controls the opening of the descending solenoid valve 23, and controls the outlet flow of the descending solenoid valve 23. In this embodiment, the buffer height L is 200 mm;

[0041] If H>L, it is in the normal descending state. At this time, the normal descending, the outlet flow of the descending solenoid valve 23 is related to the output signal C4 of the potentiometer 9, and the outlet flow of the descending solenoid valve Q=(2.5-C4)*1.2*q

[0042] If H≤L, it is in the descending buffer state, the outlet flow of the descending solenoid valve 23 is related to the output signal C1 of the lifting height sensor 4, and the outlet flow of the descending solenoid valve Q=C1*1.2*q. At this time, the outlet flow of the descending solenoid valve 23 is reduced through the valve sensor 5 to reduce the descending speed.

[0043] Wherein: H is the real-time height of the gantry, Hmax is the maximum lifting height of the gantry, L is the buffer height, the value range of L is: 150mm<L<250mm, and q is the displacement of the gear pump.

[0044] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0045] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A forklift mast lifting and lowering buffer device, comprising a slidingly connected outer mast (1), an inner mast (2) and a lifting cylinder (3) for pushing the mast to move, characterized in that: The oil supply part and the lifting control part connected to the lifting oil cylinder (3); The oil supply unit comprises a hydraulic oil tank (19), the hydraulic oil tank (19) is connected to a gear pump (18), the gear pump (18) is connected to an oil pump motor (17), the oil outlet of the gear pump (18) is connected to a lifting solenoid valve (21), the oil outlet of the lifting solenoid valve (21) is connected to the lifting oil cylinder (3), and the oil return port of the lifting oil cylinder (3) is connected to the hydraulic oil tank (19) via a descending solenoid valve (23); The lifting control unit includes a valve controller (5), and the valve controller (5) is in signal communication with the lifting solenoid valve (21) and the lowering solenoid valve (23). The valve controller (5) is connected to a lifting height sensor (4) and a switch unit (6), and the switch unit (6) includes a lowering switch (7), a lifting switch (8), and a potentiometer (9). The valve controller (5) is connected to an oil pump motor controller (15), and the oil pump motor controller (15) is in signal communication with the oil pump motor (17).

2. A forklift mast lifting and lowering buffer device according to claim 1, characterized in that: The oil outlet of the gear pump (18) is connected to a pump outlet check valve (20), the oil outlet of the pump outlet check valve (20) is in communication with a lifting solenoid valve (21), the oil outlet of the pump outlet check valve (20) is connected to a relief valve (16), the relief valve (16) is in communication with a hydraulic oil tank (19), and the oil outlet of the lifting solenoid valve (21) is provided with a valve outlet check valve (22).

3. The forklift mast lifting and lowering buffer device according to claim 1, characterized in that: The oil return port of the lifting oil cylinder (3) is connected to the hydraulic oil tank (19) via a manual unloading valve (24).

4. The forklift mast lifting and lowering buffer device according to claim 1, characterized in that: The valve controller (5) is connected to a fuel cell system (10), the fuel cell system (10) comprises a fuel cell power generation system (14), a lithium battery pack (13), and a FUC controller (11), the fuel cell power generation system (14) is connected to a DC-DC converter (12), and the lithium battery pack (13) is in communication with the DC-DC converter (12).

5. The forklift mast lifting and lowering buffer device according to claim 4, characterized in that: The lithium battery pack (13), FUC controller (11) and DC-DC converter (12) are respectively connected to the valve controller (5) and the oil pump motor controller (15).

6. A forklift mast lifting and lowering buffering control method using the buffering device as claimed in claim 1, characterized in that: The following steps are involved: S1. Determine whether the forklift is in the mast raising state or the mast lowering state according to the states of the lowering switch (7) and the raising switch (8). If the forklift is in the mast raising state, execute step 2; if the forklift is in the mast lowering state, execute step 3. S2, the valve controller (5) detects the mast position H in real time according to the lifting height sensor (4). If H≤Hmax-L, it is in a normal lifting state and normal lifting is possible. If H>Hmax-L, it is in a lifting buffer state. At this time, the valve controller (5) and the oil pump motor controller (15) control the oil pump motor speed and the outlet flow of the lifting solenoid valve (21) to reduce the lifting speed; S3, the valve controller (5) detects the mast position H in real time according to the lifting height sensor (4). If H>L, it is in a normal descending state and the mast descends normally. If H≤L, it is in a descending buffer state and the outlet flow of the electromagnetic valve (23) is lowered through the valve controller (5) to reduce the descending speed. Among them: H is the real-time height of the gantry, Hmax is the maximum lifting height of the gantry, L is the buffer height, and the value range of L is: 150mm<L<250mm.

7. A forklift mast lifting and lowering buffering control method according to claim 6, characterized in that: In S2 and S3, the valve controller (5) transmits the mast position signal C1 to the oil pump motor controller (15) through the CAN bus, and the oil pump motor controller (15) controls the rotation speed of the oil pump motor (17) according to the mast position signal C1 and the potentiometer signal C4; the valve controller (5) controls the current of the proportional electromagnet m2 of the lifting solenoid valve (21) according to the mast position signal C1 and the potentiometer signal C4, controls the opening of the lifting solenoid valve (21), and controls the outlet flow of the lifting solenoid valve (21); the valve controller (5) controls the current of the proportional electromagnet m1 of the lowering solenoid valve (23) according to the mast position signal C1 and the potentiometer signal C4, controls the opening of the lowering solenoid valve (23), and controls the outlet flow of the lowering solenoid valve (23).

8. A forklift mast lifting and lowering buffering control method according to claim 6, characterized in that: The buffer height L is 200 mm. In the normal lifting state, n=max((C4-2.5)*1200,500), Q1= (C4-2.5)*1.2*q; in the lifting buffer state, n=max((5-C1)*1200,300), Q1=(5-C1)*1.2*q; wherein: q is the displacement of the gear pump, n is the speed of the oil pump motor, Q1 is the outlet flow of the lifting battery valve, C1 is the mast position signal detected by the lifting height sensor, and C4 is the output voltage signal of the potentiometer (9).

9. A forklift mast lifting and lowering buffering control method according to claim 6, characterized in that: The buffer height L is 200 mm. In the normal descending state, Q2=(2.5-C4)*1.2*q; in the descending buffering state, Q2= C1*1.2*q; Wherein: q is the displacement of the gear pump, Q2 is the outlet flow of the descending solenoid valve, C1 is the mast position signal detected by the lifting height sensor, and C4 is the output voltage signal of the potentiometer (9).

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