A forklift gantry tilt control system and tilt control method

Abstract

The invention discloses a forklift mast tilt control system, comprising a frame and an inner mast and an outer mast arranged on the frame, the outer mast is slidably connected to the inner mast, a tilt cylinder is arranged on the frame, the inner mast is connected to a lifting height sensor, the outer mast is connected to an outer mast position sensor, and the tilt cylinder is connected to a hydraulic oil circuit; the hydraulic oil circuit comprises a gear pump, the oil outlet of the gear pump is connected to the tilt cylinder through a reversing valve, the gear pump is connected to an oil pump motor power, the oil pump motor is connected to an oil pump motor controller, the reversing valve is connected to a mast forward tilt switch and a mast backward tilt switch, the application adopts a tilt position sensor to detect the mast position in real time, realizes mast tilt in place buffering, and reduces mast tilt in place impact; adopts a lifting height sensor to detect the mast lifting height in real time, and controls the mast tilt speed; realizes that when lifting at a low level, the tilt speed is large and the efficiency is high, and when lifting at a high level, the tilt speed is small, the mast shakes less, and the safety is high.

Description

Technical Field

[0001] The invention relates to the technical field of forklift masts, and in particular to a forklift mast tilt control system and a tilt 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 mast. The fork is driven up and down by the mast sliding up and down, and the mast is driven to tilt forward and backward by the tilt cylinder.

[0003] The working process of the existing hydrogen fuel forklift mast tilting system is relatively linear. There is no forward tilt buffer system and backward tilt buffer system. The impact is large when the mast is tilted into place. The tilting speed of the mast at high and low positions is the same. The tilting speed is large when the mast is in high position. When tilted at high position, the whole vehicle shakes greatly, which can easily cause the goods to fall. Summary of the invention

[0004] The object of the present invention is to provide a forklift mast tilt control system and a tilt control method to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A forklift mast tilt control system comprises a frame, an inner mast and an outer mast arranged on the frame, the outer mast is slidably connected to the inner mast, a tilt cylinder is arranged on the frame, the inner mast is connected to a lifting height sensor, the outer mast is connected to an outer mast position sensor, and the tilt cylinder is connected to a hydraulic oil circuit;

[0007] The hydraulic oil circuit includes a gear pump, the oil outlet of the gear pump is connected to the tilt cylinder through a reversing valve, the gear pump is connected to the oil pump motor power, the oil pump motor is connected to an oil pump motor controller, the reversing valve is connected to a mast forward tilt switch and a mast backward tilt switch, and the oil pump motor controller is connected to the outer mast position sensor, the lifting height sensor, the mast forward tilt switch, and the mast backward tilt switch signals.

[0008] As a further solution of the present invention: the gear pump is connected to the hydraulic oil tank through an oil pipe, the return oil pipe of the reversing valve is connected to the hydraulic oil tank, and a return oil filter is provided between the return oil pipe of the reversing valve and the hydraulic oil tank.

[0009] As a further solution of the present invention: the oil outlet of the gear pump is connected to a relief valve, and the relief valve is connected to the hydraulic oil tank through an oil return filter.

[0010] As a further solution of the present invention: the oil pump motor controller is connected to a fuel cell system.

[0011] As a further solution of the present invention: the fuel cell system includes a FUC controller, a fuel cell power generation system, and a lithium battery pack. The fuel cell power generation system is connected to a DC-DC converter. The FUC controller, DC-DC converter, and lithium battery pack are all connected to the oil pump motor controller.

[0012] A forklift mast tilt control method comprises the following steps:

[0013] S1, the output voltage of the outer mast position sensor is positively correlated with the cylinder extension length L of the tilt cylinder. When the mast position sensor has the maximum output voltage, the tilt cylinder extension length is the maximum. The mast state is determined based on the outer mast position sensor and the tilt cylinder. If it is in the backward state, S2 is executed. If it is in the forward state, S3 is executed.

[0014] S2. Determine the mast backward tilt state according to the elongation length of the tilt cylinder. If L>10mm, the mast is in a normal backward tilt state. If L≤10mm, the mast is in a backward tilt buffer state. At this time, the oil pump motor speed needs to be reduced to reduce the mast backward tilt speed.

[0015] S3. Determine the forward tilt state of the mast according to the elongation length of the tilt cylinder. If L < Lmax-10mm, the mast is in a normal forward tilt state. If L ≥ Lmax-10mm, the mast is in a forward tilt buffer state. At this time, the oil pump motor speed needs to be reduced to reduce the mast forward tilt speed.

[0016] Wherein, L is the extension length of the tilt cylinder, Lmax is the maximum extension length of the tilt cylinder, and H is the lifting height of the gantry.

[0017] As a further solution of the present invention: the gantry position sensor detects and determines the gantry lifting height in real time. If the gantry lifting height H≤2000mm, it is in a normal lifting state; if the gantry lifting height H>2000mm, it is in a high-position lifting state.

[0018] As a further solution of the present invention: in S2, when the mast is in a normal height state, the speed of the oil pump motor when the mast is normally tilted back is n=1000, and the speed of the oil pump motor when the mast is tilted back buffering is n=max(C1*400,250); when the mast is in a high position state, the speed of the oil pump motor when the mast is normally tilted back is n=500, and the speed of the oil pump motor when the mast is tilted back buffering is n=max(C1*200,250);

[0019] Among them, C1 is the voltage signal output by the outer door frame position sensor.

[0020] As a further solution of the present invention: in S3, when the mast is at a normal height, the speed of the oil pump motor when the mast tilts forward normally is n=1200, and the speed of the oil pump motor when the mast tilts forward buffering is n=max((5-C1)*480,250); when the mast is at a high position, the speed of the oil pump motor when the mast tilts forward normally is n=600, and the speed of the oil pump motor when the mast tilts forward buffering is n=max((5-C1)*240,250);

[0021] Among them, C1 is the voltage signal output by the outer door frame position sensor.

[0022] As a further solution of the present invention: the output voltage signal C1 of the outer door frame position sensor varies in the range of 0 to 5V. When the outer door frame is in the middle position, C1=2.5V. When the door frame leans back, the range of C1 is 2.5 to 0V, and 0V corresponds to leaning back into place; when the door frame leans forward, the range of C1 is 2.5 to 5V, and 5V corresponds to leaning forward into place.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: the present application adopts a tilt position sensor to detect the gantry position in real time, and different gantry positions correspond to different oil pump motor speeds, thereby realizing gantry tilt into position buffering and reducing the impact of the gantry tilt into position; a lifting height sensor is used to detect the gantry lifting height in real time, and the gantry tilt speed is controlled according to different lifting heights; the tilt speed is high and the efficiency is high when lifting at low level, and the tilt speed is low and the gantry shakes less and the safety is high when lifting at high level. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of this embodiment;

[0025] In the figure: 1- fuel cell system, 2- oil pump motor controller, 3- outer mast position sensor, 4- lifting height sensor, 5- inner mast, 6- frame, 7- outer mast, 8- control valve stem, 9- tilt cylinder, 10- reversing valve, 11- overflow valve, 12- oil return filter, 13- hydraulic oil tank, 14- gear pump, 15- oil pump motor, 16- mast forward tilt switch, 17- mast backward switch, 18- FCU controller, 19- fuel cell power generation system, 20- DC-DC converter, 21- lithium battery pack. DETAILED DESCRIPTION

[0026] 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.

[0027] See also Figure 1 In an embodiment of the present invention, a forklift mast tilt control system includes a frame 6 and an inner mast 5 and an outer mast 7 arranged on the frame 6, the outer mast 7 is slidably connected to the inner mast 5, a tilt cylinder 9 is provided on the frame 6, the tilt cylinder 9 is connected to a hydraulic oil circuit, the hydraulic oil circuit includes a gear pump 14, the gear pump 14 is connected to a hydraulic oil tank 13 through an oil pipe, the oil outlet of the gear pump 14 is connected to the tilt cylinder 9 through a reversing valve 10, the return oil pipe of the reversing valve 10 is connected to the hydraulic oil tank 13, and a return oil filter 1 is provided between the return oil pipe of the reversing valve 10 and the hydraulic oil tank 13 2. The oil outlet of the gear pump 14 is connected to the overflow valve 11, and the overflow valve 11 is connected to the hydraulic oil tank 13 through the return oil filter 12. The gear pump 14 is connected to the oil pump motor 15, and the oil pump motor 15 is connected to the oil pump motor controller 2. The reversing valve 10 is connected to the mast forward tilt switch 16 and the mast backward tilt switch 17. The inner mast 5 is connected to the lifting height sensor 4, and the outer mast 7 is connected to the outer mast position sensor 3. The oil pump motor controller 2 is connected to the outer mast position sensor 3, the lifting height sensor 4, the mast forward tilt switch 16, and the mast backward tilt switch 17 signals.

[0028] The oil pump motor controller 2 is connected to the fuel cell system 1, and the fuel cell system 1 includes a FUC controller 18, a fuel cell power generation system 19, and a lithium battery pack 21. The fuel cell power generation system 19 is connected to a DC-DC converter 20, and the FUC controller 18, the DC-DC converter 20, and the lithium battery pack 21 are all connected to the oil pump motor controller 2.

[0029] When the mast tilts forward, the fuel cell system 1 supplies power to the pump motor 15 through the pump motor controller 2, and the pump motor 15 drives the gear pump 14 to rotate. The hydraulic oil output by the gear pump 14 passes through the right position of the reversing valve 10 to the D port of the tilting cylinder 9, and the tilting cylinder 9 pushes the outer mast 7 to swing on the frame 6, so that the mast tilts forward. The hydraulic oil in the tilting cylinder 9 flows out from the E port and returns to the hydraulic oil tank 13 through the reversing valve 10 and the return oil filter 12. When the mast tilts backward, the fuel cell system 1 supplies power to the pump motor 15 through the pump motor controller 2, and the pump motor 15 drives the gear pump 14 to rotate. The hydraulic oil output by the gear pump 14 passes through the left position of the reversing valve 10 to the E port of the tilting cylinder 9, and the tilting cylinder 9 pushes the outer mast 7 to swing on the frame 6, so that the mast tilts backward. The hydraulic oil in the tilting cylinder 9 flows out from the D port and returns to the hydraulic oil tank 13 through the reversing valve 10 and the return oil filter 12.

[0030] The mast forward tilt switch 16 signal C3 is a switch signal, and its value is 0 or 1. When C3=1, it means that the mast forward tilt switch is closed and a mast forward tilt request is sent to the controller. When C3=0, it means that the mast forward tilt switch is disconnected. The mast backward tilt switch 17 signal C4 is a switch signal, and its value is 0 or 1. When C4=1, it means that the mast backward tilt switch is closed and a mast backward tilt request is sent to the controller. When C4=0, it means that the mast backward tilt switch is disconnected.

[0031] The lifting height sensor 4 outputs a voltage signal C2 (its variation range is: 0-5V), the mast lifting height H is positively correlated with C2, and 5V corresponds to the maximum lifting height Hmax.

[0032] The voltage signal C1 (its variation range is: 0~5V) output by the outer mast position sensor 3, when the outer mast is in the middle position, C1=2.5V, when the mast is tilted backward, C1's variation range is: 2.5~0V, 0V corresponds to the backward tilting position; when the mast is tilted forward, C1's variation range is: 2.5~5V, 5V corresponds to the forward tilting position. The extension length L of the tilt cylinder is positively correlated with C1, and 5V corresponds to the maximum extension length Lmax.

[0033] A forklift mast tilt control method comprises the following steps:

[0034] S1, the output voltage of the outer mast position sensor 3 is positively correlated with the cylinder extension length L of the tilt cylinder 9. When the outer mast position sensor 3 has the maximum output voltage, the tilt cylinder 9 has the maximum extension length. The mast state is determined based on the outer mast position sensor 3 and the tilt cylinder 9. If it is in the backward state, S2 is executed. If it is in the forward state, S3 is executed.

[0035] S2, the lifting height sensor 4 detects and determines the lifting height of the mast in real time. If the lifting height H of the mast is ≤ 2000mm, it is in a normal lifting state. If the lifting height H of the mast is H>2000mm, it is in a high-position lifting state. The mast backward state is determined according to the elongation length of the tilt cylinder 9. If L>10mm, the mast is in a normal backward state. If L≤10mm, the mast is in a backward buffer state.

[0036] When the mast is at a normal height, the speed of the oil pump motor 15 is n=1000 when the mast is tilted back normally, and the speed of the oil pump motor 15 is n=max(C1*400,250) when the mast is tilted back buffering; when the mast is at a high position, the speed of the oil pump motor 15 is n=500 when the mast is tilted back normally, and the speed of the oil pump motor 15 is n=max(C1*200,250) when the mast is tilted back buffering;

[0037] S3, the lifting height sensor 4 detects and determines the lifting height of the mast in real time. If the lifting height H of the mast is less than or equal to 2000mm, it is in a normal lifting state. If the lifting height H of the mast is greater than or equal to 2000mm, it is in a high-position lifting state. The mast forward tilting state is determined according to the elongation length of the tilt cylinder 9. If L is less than Lmax-10mm, the mast is in a normal forward tilting state. If L is greater than or equal to Lmax-10mmmm, the mast is in a forward tilting buffering state. At this time, the speed of the oil pump motor 15 needs to be reduced to reduce the forward tilting speed of the mast.

[0038] When the mast is at a normal height, the speed of the oil pump motor 15 is n=1200 when the mast tilts forward normally, and the speed of the oil pump motor 15 is n=max((5-C1)*480,250) when the mast tilts forward buffering; when the mast is at a high position, the speed of the oil pump motor 15 is n=600 when the mast tilts forward normally, and the speed of the oil pump motor 15 is n=max((5-C1)*240,250) when the mast tilts forward buffering.

[0039] 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.

[0040] 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 tilt control method, characterized in that: The vehicle frame (6) comprises an inner mast (5) and an outer mast (7) arranged on the vehicle frame (6); the outer mast (7) is slidably connected to the inner mast (5); a tilting cylinder (9) is arranged on the vehicle frame (6); the inner mast (5) is connected to a lifting height sensor (4); the outer mast (7) is connected to an outer mast position sensor (3); and the tilting cylinder (9) is connected to a hydraulic oil circuit; The hydraulic oil circuit comprises a gear pump (14), the oil outlet of the gear pump (14) is connected to the tilt cylinder (9) through a reversing valve (10), the gear pump (14) is connected to an oil pump motor (15) in power, the oil pump motor (15) is connected to an oil pump motor controller (2), the reversing valve (10) is connected to a mast forward tilt switch (16) and a mast backward tilt switch (17), and the oil pump motor controller (2) is connected to signals of the outer mast position sensor (3), the lifting height sensor (4), the mast forward tilt switch (16), and the mast backward tilt switch (17); The control method comprises the following steps: S1, the output voltage of the outer mast position sensor (3) is positively correlated with the cylinder extension length L of the tilt cylinder (9). When the output voltage of the outer mast position sensor (3) is maximum, the extension length of the tilt cylinder (9) is maximum. The mast state is judged based on the outer mast position sensor (3) and the tilt cylinder (9). If the mast is in a backward state, S2 is executed. If the mast is in a forward state, S3 is executed. S2. The mast tilt state is determined according to the elongation length of the tilt oil cylinder (9). If L>10 mm, the mast is in a normal tilt state. If L≤10 mm, the mast is in a tilt buffer state. At this time, the speed of the oil pump motor (15) needs to be reduced to reduce the mast tilt speed. S3. The forward tilt state of the mast is determined according to the elongated length of the tilt oil cylinder (9). If L<Lmax-10mm, the mast is in a normal forward tilt state. If L≥Lmax-10mm, the mast is in a forward tilt buffer state. At this time, the speed of the oil pump motor (15) needs to be reduced to reduce the forward tilt speed of the mast. Wherein, L is the extension length of the tilt cylinder, Lmax is the maximum extension length of the tilt cylinder, and H is the lifting height of the gantry.

2. A forklift mast tilt control method according to claim 1, characterized in that: The gantry position sensor (3) detects and determines the gantry lifting height in real time. If the gantry lifting height H is less than or equal to 2000 mm, the gantry is in a normal lifting state. If the gantry lifting height H is greater than or equal to 2000 mm, the gantry is in a high-position lifting state.

3. A forklift mast tilt control method according to claim 2, characterized in that: In S2, when the mast is in a normal height state, the speed of the oil pump motor (15) when the mast is normally tilted back is n=1000, and the speed of the oil pump motor (15) when the mast is tilted back buffering is n=max(C1*400,250); when the mast is in a high position state, the speed of the oil pump motor (15) when the mast is normally tilted back is n=500, and the speed of the oil pump motor (15) when the mast is tilted back buffering is n=max(C1*200,250); Wherein, C1 is the voltage signal output by the outer door frame position sensor (3).

4. A forklift mast tilt control method according to claim 3, characterized in that: In S3, when the mast is in a normal height state, the speed of the oil pump motor (15) when the mast is tilted forward normally is n=1200, and the speed of the oil pump motor (15) when the mast is tilted forward buffering is n=max((5-C1)*480,250); when the mast is in a high position state, the speed of the oil pump motor (15) when the mast is tilted forward normally is n=600, and the speed of the oil pump motor (15) when the mast is tilted forward buffering is n=max((5-C1)*240,250); Wherein, C1 is the voltage signal output by the outer door frame position sensor (3).

5. A forklift mast tilt control method according to claim 3 or 4, characterized in that: The output voltage signal C1 of the outer mast position sensor (3) varies in the range of 0 to 5V. When the outer mast is in the middle position, C1=2.5V. When the mast is tilted backward, C1 varies in the range of 2.5 to 0V, with 0V corresponding to the mast being tilted backward in place. When the mast is tilted forward, C1 varies in the range of 2.5 to 5V, with 5V corresponding to the mast being tilted forward in place.

6. A forklift mast tilt control system for use in the forklift mast tilt control method according to any one of claims 1 to 5, characterized in that: The gear pump (14) is connected to a hydraulic oil tank (13) via an oil pipe, the oil return pipe of the reversing valve (10) is in communication with the hydraulic oil tank (13), and an oil return filter (12) is provided between the oil return pipe of the reversing valve (10) and the hydraulic oil tank (13).

7. A forklift mast tilt control system according to claim 6, characterized in that: The oil outlet of the gear pump (14) is connected to a relief valve (11), and the relief valve (11) is connected to the hydraulic oil tank (13) through an oil return filter (12).

8. A forklift mast tilt control system according to claim 6, characterized in that: The oil pump motor controller (2) is connected to the fuel cell system (1).

9. A forklift mast tilt control system according to claim 8, characterized in that: The fuel cell system (1) comprises a FUC controller (18), a fuel cell power generation system (19), and a lithium battery pack (21); the fuel cell power generation system (19) is connected to a DC-DC converter (20); and the FUC controller (18), the DC-DC converter (20), and the lithium battery pack (21) are all connected to the oil pump motor controller (2).

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