Control method and apparatus of heavy-duty reach truck

Abstract

The present application discloses a control method and apparatus of a heavy-duty reach truck. The method comprises: when forks are below a first height, a truck travels at a first travel speed, accelerates at a first acceleration rate, and decelerates at a first deceleration rate; when the forks are between the first height and a second height, the truck travels at a second travel speed, accelerates at a second acceleration rate, and decelerates at a second deceleration rate; when the forks are between the second height and a third height, the truck travels at a third travel speed, accelerates at a third acceleration rate, and decelerates at a third deceleration rate; and when the forks are above the third height, the truck travels at a fourth travel speed, accelerates at a fourth acceleration rate, and decelerates at a fourth deceleration rate, wherein the third height > the second height > the first height, the first travel speed > the second travel speed > the third travel speed > the fourth travel speed, and the first acceleration / deceleration rate > the second acceleration / deceleration rate > the third acceleration / deceleration rate > the fourth acceleration / deceleration rate. According to the present application, the mast oscillation amplitude when the forks are at a high-level storage position is reduced, thereby enhancing the stability of the truck.

Description

A control method and device for a heavy-duty forklift with a reach-fork Technical Field

[0001] The present application belongs to the technical field of special mechanical equipment control, and in particular relates to a control method and device for a heavy-duty forklift with a reach-fork mechanism. Background Art

[0002] A heavy-duty reach truck with forks is a type of reach truck. It differs from an ordinary reach truck in the way it moves forward and backward. An ordinary reach truck uses the mast to move forward and backward, while a heavy-duty reach truck uses the attachments on the mast to move forward and backward. Whether the mast or attachments are moving forward and backward, the forks will shake when the mast is raised to more than 9 meters. When there is cargo on the forks, there is a risk of the cargo falling off. Currently, there is no technical solution to the problems of large mast shaking, cargo falling risk, and poor vehicle stability when the forks are raised to a certain height. Summary of the Invention

[0003] In order to solve the deficiencies in the prior art, the present application proposes a control method and device for a heavy-duty forklift with a reach-fork mechanism.

[0004] A first aspect of the present invention provides a control method for a heavy-duty reach forklift, comprising:

[0005] When the forklift lift height is below the first height, the forklift travels at a first travel speed, accelerates at a first acceleration rate, and decelerates at a first deceleration rate;

[0006] When the forklift is between the first height and the second height, the forklift travels at a second travel speed, accelerates at a second acceleration rate, and decelerates at a second deceleration rate;

[0007] When the forklift is between the second height and the third height, the forklift travels at a third travel speed, accelerates at a third acceleration rate, and decelerates at a third deceleration rate;

[0008] When the forklift lift height is above the third height, the forklift travels at a fourth travel speed, accelerates at a fourth acceleration rate, and decelerates at a fourth deceleration rate;

[0009] Among them, the third height > the second height > the first height; the first driving speed > the second driving speed > the third driving speed > the fourth driving speed; the first acceleration rate > the second acceleration rate > the third acceleration rate > the fourth acceleration rate; the first deceleration rate > the second deceleration rate > the third deceleration rate > the fourth deceleration rate.

[0010] In a preferred embodiment of the present application, it also includes:

[0011] When the fork lifting height is below the first height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at the deceleration rate Q2 and moves forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at the deceleration rate Q3 and moves backward to the end point;

[0012] When the fork lifting height is between the first height and the second height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at 70% Q2 to move forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at 70% Q3 to move backward to the end point;

[0013] When the fork lifting height is between the second height and the third height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at 55% Q2 and moves forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at 55% Q3 and moves backward to the end point;

[0014] When the fork lifting height is above the third height, when the fork moves forward and triggers the forward buffer switch, the fork moves forward at a deceleration rate of 30%Q2 to the end point; when the fork moves backward and triggers the backward buffer switch, the fork moves backward at a deceleration rate of 30%Q3 to the end point.

[0015] In a preferred embodiment of the present application, when the lifting height of the forklift is below the first height, the forklift is braked using the maximum braking force in the braking state, wherein the maximum braking force is calculated as follows:

[0016]

[0017] Where, is the braking force when the vehicle is traveling at maximum speed, is the deceleration rate of the vehicle when it is reduced from the maximum speed to zero, is the total weight of the vehicle.

[0018] In a preferred embodiment of the present application, the first height is 5 meters, the second height is 7 meters, and the third height is 9 meters.

[0019] In a preferred embodiment of the present application, the second driving speed = 80% * the first driving speed, the third driving speed = 60% * the first driving speed, and the fourth driving speed = 40% * the first driving speed;

[0020] The second acceleration rate = 80% * the first acceleration rate, the third acceleration rate = 60% * the first acceleration rate, the fourth acceleration rate = 40% * the first acceleration rate;

[0021] The second deceleration rate = 80% * the first deceleration rate, the third deceleration rate = 60% * the first deceleration rate, and the fourth deceleration rate = 40% * the first deceleration rate.

[0022] In a preferred embodiment of the present application, when the fork is lifted between the first height and the second height, the braking force is 80%. When the fork is between the second and third heights, the braking force is 60%. When the fork is at the third height or above and braking, the braking force is 40%. .

[0023] In a preferred embodiment of the present application, when the fork lifting height is below the first height, when the fork moves forward, the forward speed is Maximum, forward acceleration rate ; When the fork moves backward, the backward speed Maximum, backward acceleration rate ;

[0024] When the fork lift height is between the first height and the second height, when the fork moves forward, the forward speed is 70% , the forward acceleration rate is 70% When the fork moves backward, the backward speed is 70% , the backward acceleration rate is 70% ;

[0025] When the fork lift height is between the second and third heights, when the fork moves forward, the forward speed is 55%. , the forward acceleration rate is 55% When the fork moves backward, the backward speed is 55% , the backward acceleration rate is 55% ;

[0026] When the fork moves forward above the third height, the forward speed is 30%. , forward acceleration rate is 30% When the fork moves backward, the backward speed is 30% , the backward acceleration rate is 30% .

[0027] In a second aspect, a control device for a heavy-duty forklift with a reach-fork system is proposed, comprising:

[0028] Controller, instrument, oil pump motor, traction motor, bearing encoder, zero position switch, height switch, brake switch, forward buffer switch and backward buffer switch;

[0029] The controller is in communication with the bearing encoder, the zero position switch, the height switch, the forward movement buffer switch, and the backward movement buffer switch. The controller receives signals from each component to calculate the lifting height of the fork, and displays the lifting height of the fork in real time on the instrument through communication. The controller obtains forklift movement control parameters and fork movement control parameters according to the control method for a heavy-duty fork-reaching forklift according to the first aspect, and controls the operation of the traction motor and the oil pump motor. The forklift movement control parameters include: driving speed, acceleration rate, and deceleration rate; and the fork movement control parameters include: forward speed, backward speed, forward acceleration rate, backward acceleration rate, forward deceleration rate, and backward deceleration rate.

[0030] The brake switch is used to provide a brake signal to the forklift. When the brake switch is released, the traction motor will perform regenerative braking to stop the forklift in motion.

[0031] The beneficial effects of the technical solutions provided by some embodiments of the present application include at least:

[0032] The present application provides a control method and device for a heavy-duty forklift with a forward-moving fork, which can reduce the shaking of the mast when the forks are raised to a high cargo position, increase the stability of the forklift, improve operating comfort and safety, avoid safety hazards, and improve utilization efficiency.

[0033] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description or be understood by practicing the present application. The objectives and other advantages of the present application are realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a flow chart of a control method for a heavy-duty reach forklift according to an embodiment of the present application;

[0035] FIG2 is a circuit diagram of a control device for a heavy-duty reach-forklift truck according to an embodiment of the present application. Modes for Carrying Out the Invention

[0036] In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

[0037] Example 1:

[0038] A control method for a heavy-duty reach forklift provided in an embodiment of the present application will be described in detail below with reference to FIG1 .

[0039] Please refer to Figure 1, which is a flow chart of a method for controlling a heavy-duty reach truck according to an embodiment of the present application. As shown in Figure 1, the method according to an embodiment of the present application may include the following steps:

[0040] Step S1: the forklift controls the fork to lift;

[0041] Step S2: Determine within which range the fork lift height falls;

[0042] Step S3A: When the forklift lifting height is below the first height, the forklift travels at a first travel speed, accelerates at a first acceleration rate, and decelerates at a first deceleration rate;

[0043] Step S3B: When the forklift lifting height is between the first height and the second height, the forklift travels at a second travel speed, accelerates at a second acceleration rate, and decelerates at a second deceleration rate;

[0044] Step S3C: When the forklift lifting height is between the second height and the third height, the forklift travels at a third travel speed, accelerates at a third acceleration rate, and decelerates at a third deceleration rate;

[0045] Step S3D: When the forklift lifting height is above the third height, the forklift travels at a fourth travel speed, accelerates at a fourth acceleration rate, and decelerates at a fourth deceleration rate;

[0046] Among them, the third height > the second height > the first height; the first driving speed > the second driving speed > the third driving speed > the fourth driving speed; the first acceleration rate > the second acceleration rate > the third acceleration rate > the fourth acceleration rate; the first deceleration rate > the second deceleration rate > the third deceleration rate > the fourth deceleration rate.

[0047] In a possible implementation, the following further includes:

[0048] When the fork lifting height is below the first height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at the deceleration rate Q2 and moves forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at the deceleration rate Q3 and moves backward to the end point;

[0049] When the fork lifting height is between the first height and the second height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at 70% Q2 to move forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at 70% Q3 to move backward to the end point;

[0050] When the fork lifting height is between the second height and the third height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at 55% Q2 and moves forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at 55% Q3 and moves backward to the end point;

[0051] When the fork lifting height is above the third height, when the fork moves forward and triggers the forward buffer switch, the fork moves forward at a deceleration rate of 30%Q2 to the end point; when the fork moves backward and triggers the backward buffer switch, the fork moves backward at a deceleration rate of 30%Q3 to the end point.

[0052] In a possible implementation, the forklift further includes braking with a maximum braking force when the forklift is below the first height, wherein the maximum braking force is calculated as follows:

[0053]

[0054] is the braking force when the vehicle is traveling at maximum speed, is the deceleration rate of the vehicle when it is reduced from the maximum speed to zero, is the total weight of the vehicle.

[0055] In a possible implementation manner, the first height is 5 meters, the second height is 7 meters, and the third height is 9 meters.

[0056] In a possible implementation manner, the second driving speed = 80% * the first driving speed, the third driving speed = 60% * the first driving speed, and the fourth driving speed = 40% * the first driving speed;

[0057] The second acceleration rate = 80% * the first acceleration rate, the third acceleration rate = 60% * the first acceleration rate, the fourth acceleration rate = 40% * the first acceleration rate;

[0058] The second deceleration rate = 80% * the first deceleration rate, the third deceleration rate = 60% * the first deceleration rate, and the fourth deceleration rate = 40% * the first deceleration rate.

[0059] In a possible embodiment, the braking force is 80% when the fork is between the first height and the second height. When the fork is between the second and third heights, the braking force is 60%. When the fork is at the third height or above and braking, the braking force is 40%. .

[0060] In a possible embodiment, when the fork lifting height is below the first height, when the fork moves forward, the forward speed is , forward acceleration rate ; When the fork moves backward, the backward speed , backward acceleration rate ;

[0061] When the fork lift height is between the first height and the second height, when the fork moves forward, the forward speed is 70% , the forward acceleration rate is 70% When the fork moves backward, the backward speed is 70% , the backward acceleration rate is 70% ;

[0062] When the fork lift height is between the second and third heights, when the fork moves forward, the forward speed is 55%. , the forward acceleration rate is 55% When the fork moves backward, the backward speed is 55% , the backward acceleration rate is 55% ;

[0063] When the fork moves forward above the third height, the forward speed is 30%. , forward acceleration rate is 30% When the fork moves backward, the backward speed is 30% , the backward acceleration rate is 30% .

[0064] The control method for a heavy-duty forklift with a reach-fork system disclosed in this embodiment primarily involves control strategies for the traction motor and oil pump motor under different operating conditions. This method primarily involves controlling the forklift at different heights, such as low and high cargo positions. The primary control elements include: the speed, acceleration, and deceleration rates of the forklift during travel; the braking force during braking; and the speed, acceleration, and deceleration rates of the forklift during forward and backward movement. This application can reduce mast sway when the forklift reaches a high cargo position, thereby increasing forklift stability, improving operator comfort and safety, avoiding potential safety hazards, and improving operational efficiency.

[0065] Example 2:

[0066] This application proposes a control device for a heavy-duty forklift with a reach-fork system, comprising:

[0067] Controller 5, instrument 7, oil pump motor 10, traction motor 11, bearing encoder 12, zero switch 13, height switch 14, brake switch 15, forward buffer switch 16 and backward buffer switch 17;

[0068] The controller 5 is in communication with the bearing encoder 12, the zero position switch 13, the height switch 14, the forward movement buffer switch 16, and the backward movement buffer switch 17. The controller 5 receives signals from each component to calculate the lifting height of the fork, and displays the lifting height of the fork in real time on the instrument 7 through communication. The controller 5 also controls the operation of the traction motor 11 and the oil pump motor 10 by obtaining the forklift movement control parameters and the fork movement control parameters according to the control method for the heavy-duty forward-moving forklift described in Example 1. The forklift movement control parameters include: driving speed, acceleration rate, and deceleration rate; the fork movement control parameters include: forward speed, backward speed, forward acceleration rate, backward acceleration rate, forward deceleration rate, and backward deceleration rate.

[0069] The brake switch 15 is used to provide a brake signal to the forklift. When the brake switch is released, the traction motor 11 will perform a regenerative braking function to stop the forklift in the driving state.

[0070] The following example illustrates the specific implementation process of the first and second embodiments of the present application in detail. As shown in FIG2 , a control device for a heavy-duty forklift with a reach type fork includes:

[0071] Lithium battery assembly 1, emergency power off switch 2, key switch 3, main contactor 4, controller 5, valve controller 6, instrument 7, DC-DC converter 8, multi-function handle 9, oil pump motor 10, traction motor 11, bearing encoder 12, zero position switch 13, height switch 14, brake switch 15, forward buffer switch 16 and backward buffer switch 17; in addition, fuses F1, F2, F3, F4 and F5 are also provided in the circuit to protect the safety of each circuit.

[0072] The lithium battery assembly 1, the emergency power off switch 2, the key switch 3 are connected with the DC-DC converter 8 and the multi-function handle 9 to form a power circuit;

[0073] The valve controller 6 is connected to the bearing encoder 12, the zero position switch 13, the height switch 14, the forward buffer switch 16 and the backward buffer switch 17, and calculates the lifting height of the fork through the bearing encoder 12, the zero position switch 13 and the height switch 14, and displays the lifting height of the fork in real time on the instrument 7 through communication;

[0074] The controller 5 and the valve controller 6 are connected to the lithium battery assembly 1 through the main contactor 4 to form a loop;

[0075] The brake switch 15 is used to provide a brake signal to the forklift. When the brake switch is released, the traction motor 11 will perform a regenerative braking function to stop the forklift in the driving state.

[0076] The circuit principles of this embodiment are as follows: The input of the emergency power-off switch 2 is normally powered, drawn from the front stage of the discharge relay in the lithium battery assembly 1. The key switch 3 is connected in series with the emergency power-off switch 2. When the emergency power-off switch 2 is energized and the key switch 3 is closed, the controller 5, valve controller 6, and the key port of the instrument 7 are energized. Simultaneously, the discharge relay of the lithium battery assembly 1 is closed, the main contactor 4 is closed, and the DC-DC converter 8 is energized, generating a 12V output voltage. The brake switch 15 primarily provides a braking signal to the vehicle. When the brake switch is released, the traction motor 11 performs regenerative braking, bringing the forklift to a stop while in motion. The bearing encoder 12, zero position switch 13, and height switch 14 primarily calculate the forklift lift height, which is displayed in real time on the instrument 7 via CAN bus communication. The bearing encoder 12 is an incremental encoder that outputs pulse signals. The zero position switch 13 and the height switch 14 are both standard Hall-effect PNP switches. When a metal plate comes into close contact with them, they generate a signal that is sent to the valve controller 6, which in turn transmits the signal to the meter 7 to calculate the current fork lift height. The forward and reverse buffer switches 16 and 17 are also standard Hall-effect PNP switches. When the forks move forward, a signal from the forward buffer switch 16 changes the speed of the forks. Similarly, when the forks move backward, a signal from the reverse buffer switch 17 changes the speed of the forks. The lithium battery assembly 1, controller 5, valve controller 6, meter 7, and multi-function handle 9 communicate via the CAN bus. Once the lithium battery assembly 1, controller 5, valve controller 6, meter 7, and multi-function handle 9 are powered on and self-tested, the vehicle begins operation.

[0077] To address the amount of sway when the forks are lifted to high cargo positions, different forks are lifted to different heights, mainly divided into three heights: 5 meters, 7 meters, and 9 meters. Four state quantities: 0-5 meters, 5-7 meters, 7-9 meters, and above 9 meters. The control method for the heavy-duty forklift used in the controller 5 is as follows:

[0078] When the forklift lift height is 0-5 meters: in the driving state, the forklift speed Maximum, acceleration rate Maximum deceleration rate Maximum; in braking state, braking force Maximum; when the fork moves forward, the forward speed Maximum, forward acceleration rate Maximum, when the fork moves forward to the forward buffer switch and there is a signal, the fork starts to decelerate. At this time, the deceleration rate Maximum, fork in Move forward to the end point at a deceleration rate; when the fork moves backward, the backward speed Maximum, backward acceleration rate Maximum, when the fork moves backward to the point where the rearward buffer switch has a signal, the fork starts to slow down. At this time, the deceleration rate Maximum, fork in Move back to the end point at a deceleration rate.

[0079] When the forklift is lifted to a height of 5-7 meters: in driving state, the forklift travels at 80% speed , the acceleration rate is 80% , the deceleration rate is 80% ; In the braking state, the braking force is 80% ; When the fork moves forward, the forward speed is 70% , the forward acceleration rate is 70% When the fork moves forward to the point where the forward buffer switch has a signal, the fork starts to decelerate, and the deceleration rate is 70% at this time. , the fork is at 70% Move forward to the end point at a deceleration rate; when the fork moves backward, the backward speed is 70% , the backward acceleration rate is 70% When the fork moves backward and the rearward buffer switch has a signal, the fork starts to slow down, and the deceleration rate is 70% at this time. , the fork is at 70% Move back to the end point at a deceleration rate.

[0080] When the forklift is lifted to a height of 7-9 meters: in driving state, the forklift travels at a speed of 60% , the acceleration rate is 60% , the deceleration rate is 60% ; In the braking state, the braking force is 60% ; When the fork moves forward, the forward speed is 55% , the forward acceleration rate is 55% When the fork moves forward to the point where the forward buffer switch has a signal, the fork begins to decelerate, and the deceleration rate is 55% at this time. , the fork is at 55% Move forward to the end point at a deceleration rate; when the fork moves backward, the backward speed is 55%. , the backward acceleration rate is 55% When the fork moves backward and the rearward buffer switch has a signal, the fork starts to slow down, and the deceleration rate is 55% at this time. , the fork is at 55% Move back to the end point at a deceleration rate.

[0081] When the forklift is lifted to a height of 9 meters or more: the forklift's travel speed is 40% when in motion. , the acceleration rate is 40% , the deceleration rate is 40% ; In the braking state, the braking force is 40% ; When the fork moves forward, the forward speed is 30% , forward acceleration rate is 30% When the fork moves forward to the point where the forward buffer switch has a signal, the fork starts to decelerate, and the deceleration rate is 30% at this time. , the fork is at 30% Move forward to the end point at a deceleration rate; when the fork moves backward, the backward speed is 30% , the backward acceleration rate is 30% When the fork moves backward and the rearward buffer switch has a signal, the fork starts to slow down, and the deceleration rate is 30% at this time. , the fork is at 30% Move back to the end point at a deceleration rate.

[0082] The parameters and formulas involved in this application are as follows:

[0083]

[0084] In the formula -The maximum speed of the vehicle; - The time it takes for the vehicle to reach its maximum speed from zero; -The acceleration rate of the vehicle to reach the maximum speed;

[0085]

[0086] - The time it takes for the vehicle's speed to decrease from the maximum speed to zero; - The deceleration rate of the vehicle when it is reduced from the maximum speed to zero;

[0087]

[0088] - Braking force at maximum vehicle speed; - Gross weight of the vehicle;

[0089]

[0090] -The maximum forward speed of the vehicle when moving forward; -The time it takes for the vehicle to reach its maximum forward speed from zero; -The acceleration rate at which the vehicle reaches its maximum forward speed when moving forward;

[0091]

[0092] -The time it takes for the vehicle's forward speed to decrease from the maximum forward speed to zero; -The deceleration rate when the vehicle moves forward from the maximum forward speed to zero;

[0093]

[0094] -The maximum rearward movement speed of the vehicle; -The time it takes for the vehicle's rearward speed to reach its maximum rearward speed from zero; -The acceleration rate to reach the maximum rearward speed when the vehicle moves backward;

[0095]

[0096] -The time it takes for the vehicle's rearward speed to decrease from the maximum rearward speed to zero; -The deceleration rate when the vehicle moves backward from the maximum rearward speed to zero.

[0097] Those skilled in the art will clearly understand that for the convenience and brevity of description, the specific working principle of the device described above, the specific forklift control method and beneficial effects can be referred to the contents of the aforementioned method embodiment, and will not be repeated here.

Claims

1. A control method for a heavy-duty forklift, characterized in that: include: When the forklift lift height is below the first height, the forklift travels at a first travel speed, accelerates at a first acceleration rate, and decelerates at a first deceleration rate; When the forklift is between the first height and the second height, the forklift travels at a second travel speed, accelerates at a second acceleration rate, and decelerates at a second deceleration rate; When the forklift is between the second height and the third height, the forklift travels at a third travel speed, accelerates at a third acceleration rate, and decelerates at a third deceleration rate; When the forklift lift height is above the third height, the forklift travels at a fourth travel speed, accelerates at a fourth acceleration rate, and decelerates at a fourth deceleration rate; Among them, the third height > the second height > the first height; the first driving speed > the second driving speed > the third driving speed > the fourth driving speed; the first acceleration rate > the second acceleration rate > the third acceleration rate > the fourth acceleration rate; the first deceleration rate > the second deceleration rate > the third deceleration rate > the fourth deceleration rate.

2. The control method of a heavy-duty reach forklift according to claim 1, wherein: Also includes: When the fork lifting height is below the first height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at the deceleration rate Q2 and moves forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at the deceleration rate Q3 and moves backward to the end point; When the fork lifting height is between the first height and the second height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at 70% Q2 to move forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at 70% Q3 to move backward to the end point; When the fork lifting height is between the second height and the third height, when the fork moves forward and triggers the forward buffer switch, the fork decelerates at 55% Q2 and moves forward to the end point; when the fork moves backward and triggers the backward buffer switch, the fork decelerates at 55% Q3 and moves backward to the end point; When the fork lifting height is above the third height, when the fork moves forward and triggers the forward buffer switch, the fork moves forward at a deceleration rate of 30%Q2 to the end point; when the fork moves backward and triggers the backward buffer switch, the fork moves backward at a deceleration rate of 30%Q3 to the end point.

3. The control method of a heavy-duty reach forklift according to claim 1, wherein: The forklift is also provided with the following formula: when the forklift is braked when the lifting height of the forklift is below the first height, the forklift is braked with the maximum braking force, wherein the maximum braking force is calculated as follows; Where, is the braking force when the vehicle is traveling at maximum speed, is the deceleration rate of the vehicle when it is reduced from the maximum speed to zero, is the total weight of the vehicle.

4. The control method of a heavy-duty reach forklift according to claim 2, wherein: The first height is 5 meters, the second height is 7 meters, and the third height is 9 meters.

5. The control method of a heavy-duty reach forklift according to claim 4, characterized in that: The second driving speed = 80% * the first driving speed, the third driving speed = 60% * the first driving speed, the fourth driving speed = 40% * the first driving speed; The second acceleration rate = 80% * the first acceleration rate, the third acceleration rate = 60% * the first acceleration rate, the fourth acceleration rate = 40% * the first acceleration rate; The second deceleration rate = 80% * the first deceleration rate, the third deceleration rate = 60% * the first deceleration rate, and the fourth deceleration rate = 40% * the first deceleration rate.

6. The control method of a heavy-duty reach forklift according to claim 3, wherein: It also includes that when the fork lift height is between the first height and the second height, the braking force is 80%. When the fork is between the second and third heights, the braking force is 60%. When the fork is at the third height or above and braking, the braking force is 40%. .

7. The control method of a heavy-duty reach forklift according to claim 5, characterized in that: It also includes that when the fork lifting height is below the first height, when the fork moves forward, the forward speed is , the forward acceleration rate is ; When the fork moves backward, the backward speed is , the backward acceleration rate is ; When the fork lift height is between the first height and the second height, when the fork moves forward, the forward speed is 70% , the forward acceleration rate is 70% When the fork moves backward, the backward speed is 70% , the backward acceleration rate is 70% ； When the fork lift height is between the second and third heights, when the fork moves forward, the forward speed is 55%. , the forward acceleration rate is 55% When the fork moves backward, the backward speed is 55% , the backward acceleration rate is 55% ； When the fork moves forward above the third height, the forward speed is 30%. , forward acceleration rate is 30% When the fork moves backward, the backward speed is 30% , the backward acceleration rate is 30% 。 8. A heavy-duty forklift control device, characterized in that: It includes a controller (5), an instrument (7), an oil pump motor (10), a traction motor (11), a bearing encoder (12), a zero position switch (13), a height switch (14), a brake switch (15), a forward buffer switch (16) and a backward buffer switch (17); The controller (5) is respectively connected to the bearing encoder (12), the zero position switch (13), the height switch (14), the forward buffer switch (16) and the backward buffer switch (17). The controller (5) receives signals from each component to calculate the lifting height of the fork, and displays the lifting height of the fork on the instrument (7) in real time through communication. The forklift movement control parameters and the fork movement control parameters obtained according to the heavy-duty fork forward moving forklift control method according to any one of claims 1 to 7 are used to control the operation of the traction motor (11) and the oil pump motor (10); The forklift movement control parameters include: driving speed, acceleration rate and deceleration rate; the fork movement control parameters include: forward speed, backward speed, forward acceleration rate, backward acceleration rate, forward deceleration rate and backward deceleration rate; The brake switch (15) is used to provide a brake signal to the forklift. When the brake switch is released, the traction motor (11) will realize a regenerative braking function to stop the forklift in a driving state.

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