Forward moving type forklift truck fork lowering control method

Abstract

This invention discloses a forklift fork descent control method. The method includes the following steps: monitoring the output signal C1 of the descent switch, the output signal C2 of the lifting / descent handle potentiometer, and the fork lifting height signal C3; and determining four descent types based on the fork's position (high or low) and the user's desired rapid or slow descent: rapid descent from high position, slow descent from high position, rapid descent from low position, and slow descent from low position. The method determines the user-selected descent type based on the monitored return values. Simultaneously, the controller precisely controls the closing speed of the descent proportional solenoid valve according to the different descent control methods corresponding to each type. This prevents the forks loaded with goods from stopping rapidly, causing the mast and the entire vehicle to shake, affecting overall vehicle safety, and also prevents the forks from failing to stop at the accurate position, thus impacting operational efficiency.

Description

Technical Field

[0001] This invention relates to the field of forklift technology, and more particularly to a method for controlling the descent of forks in a reach truck. Background Technology

[0002] When the forks of an existing reach truck are lowered, the solenoid valve using the same closing speed for different lowering speeds presents the following problems:

[0003] 1. Unstable stopping during rapid fork descent: When the driver operates the fork descent handle to control the forks (including cargo) to descend rapidly, releasing the handle causes the forks (including cargo) to stop abruptly, resulting in swaying of the mast and the entire vehicle, affecting overall vehicle safety. 2. Inaccurate stopping during slow fork descent: When the driver operates the fork descent handle to control the forks (including cargo) to descend slowly, releasing the handle causes the forks to fail to stop at the precise position, affecting operational efficiency. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, one objective of this invention is to provide a fork descent control method for a reach truck, which categorizes fork descent into four types based on fork status, and provides a different fork descent control method for each type, with the controller precisely controlling the closing speed of the descent proportional solenoid valve.

[0005] According to the present invention, a method for controlling the lowering of forks in a reach truck includes the following steps:

[0006] S1: Monitor the output signal C1 of the descent switch, the output signal C2 of the lifting and lowering handle potentiometer, and the fork lifting height signal C3. Execute step S2 based on the return value.

[0007] S2: When C1=1, the fork lifting height H≥H 预 C2 decreases from a large value to a small value, and the initial value of C2 is greater than C2. 预 When C1=1, it indicates that the fork lifting height H≥H is output as a command for rapid descent from a high position, and step S3 is executed; when C1=1, the fork lifting height H≥H 预 C2 decreases from a large value to a small value, and the initial value of C2 is less than or equal to C2. 预 When C1=1, it indicates that the output command for slow descent of the forks from a high position is executed, and step S4 is performed; when C1=1, the fork lifting height H<H 预 C2 decreases from a large value to a small value, and the initial value of C2 is greater than C2. 预 When C1=1, it indicates that the fork lifting height H < H is being executed. 预 C2 decreases from a large value to a small value, and the initial value of C2 is less than or equal to C2. 预 When this occurs, it indicates that a command to slowly lower the forks at a low position is output, and step S6 is executed.

[0008] S3: The controller receives a command for the forks to descend rapidly from a high position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V1. The formula for the preset speed V1 is:

[0009] V1 = X0 ÷ t1;

[0010] Where X0 represents the current opening degree of the descent proportional solenoid valve, and t1 represents the closing time of the descent proportional solenoid valve when the forks descend rapidly from a high position.

[0011] t1=[(C2 初始 -2.5)÷2.5]×K1×K2×t0×[H max [×C3÷(5×7000)];

[0012] Among them, C2 初始 This indicates the potentiometer signal when the lifting / lowering handle is released; K1 represents the proportional solenoid valve closing time adjustment coefficient when the forks descend rapidly; K2 represents the proportional solenoid valve closing time adjustment coefficient when the forks descend from a high position; t0 represents the standard closing time of the proportional solenoid valve during descent; H... max Indicates the maximum lifting height of the forks;

[0013] S4: The controller receives a command for the forks to descend slowly from their high position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V2. The formula for the preset speed V2 is:

[0014] V2 = X0 ÷ t2;

[0015] Where t2 represents the closing time of the proportional solenoid valve when the forks are slowly descending from a high position.

[0016] t2=[(C2 初始 -2.5)÷2.5]×K3×t0×[H max [×C3÷(5×7000)];

[0017] Wherein, K3 represents the adjustment coefficient for the closing time of the proportional solenoid valve when the forks descend slowly;

[0018] S5: The controller receives a command for the forks to descend rapidly from their low position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V3. The formula for the preset speed V3 is:

[0019] V3 = X0 ÷ t3;

[0020] Where t3 represents the closing time of the solenoid valve for the descent ratio when the forks are rapidly descending from a low position.

[0021] t3=[(C2 初始-2.5)÷2.5]×K1×t0×[H max [×C3÷(5×7000)];

[0022] S6: The controller receives a low-position slow descent command for the forks, and simultaneously the lifting and lowering handles are released. The controller then controls the descent proportional solenoid valve to close at a preset speed V4. The formula for the preset speed V4 is:

[0023] V4 = X0 ÷ t4;

[0024] t4 represents the closing time of the solenoid valve when the forks are slowly descending from a low position;

[0025] t4=[(C2 初始 -2.5)÷2.5]×K3×K4×t0×[H max [×C3÷(5×7000)];

[0026] K4 represents the adjustment coefficient for the closing time of the proportional solenoid valve when the valve is in a low-position descent.

[0027] Preferably, in step S2, the fork lifting height H = H max ×C3÷5.

[0028] Preferably, in step S2, C2 预 It is 3.5V.

[0029] Preferably, in step S2, H 预 It is 7000mm.

[0030] Preferably, X0, representing the current opening degree of the descent proportional solenoid valve, is defined as [(C2...]. 初始 -2.5)÷2.5]×X max ;

[0031] Where X max This indicates the maximum opening degree of the proportional solenoid valve.

[0032] Preferably, in step S3, when the forks descend rapidly, the value range of the proportional solenoid valve closing time adjustment coefficient K1 is 1-2, and when the forks descend from a high position, the value range of the proportional solenoid valve closing time adjustment coefficient K2 is 1-1.5.

[0033] Preferably, in step S4, when the forks descend slowly, the value range of the proportional solenoid valve closing time adjustment coefficient K3 is 0.5-1.

[0034] Preferably, when the valve is descending to a low position, the value range of the proportional solenoid valve closing time adjustment coefficient K4 is 0.5-1.

[0035] The beneficial effects of this invention are as follows: It monitors the output signal C1 of the lowering switch, the output signal C2 of the lifting / lowering handle potentiometer, and the fork lifting height signal C3. Based on whether the forks are in a high or low position and the user's requirements for rapid or slow lowering, it categorizes the descent into four types: rapid descent from a high fork position, slow descent from a high fork position, rapid descent from a low fork position, and slow descent from a low fork position. The controller determines the user's selected fork descent type based on the monitored return values. Simultaneously, according to different fork descent control methods corresponding to each type, the controller precisely controls the closing speed of the descent ratio solenoid valve. This avoids the phenomenon where the forks carrying goods stop abruptly during rapid descent, causing the mast and the entire vehicle to shake, affecting overall vehicle safety. It also avoids the phenomenon where the forks cannot stop at the accurate position during slow descent, affecting operational efficiency. Attached Figure Description

[0036] In the attached diagram:

[0037] Figure 1 This is a flowchart of a forklift fork descent control method proposed in this invention. Detailed Implementation

[0038] Example 1:

[0039] Reference Figure 1 A method for controlling the lowering of forks in a reach truck, comprising the following steps:

[0040] S1: Monitor the output signal C1 of the descent switch, the output signal C2 of the lifting and lowering handle potentiometer, and the fork lifting height signal C3. Execute step S2 based on the return value.

[0041] S2: When C1=1, the fork lifting height H≥7000mm (H=H max ×C3÷5, calculate the fork lifting height H based on the C3 signal. When C2 decreases from a large value and the initial value of C2 is greater than 3.5V, it indicates that the fork is rapidly descending from a high position, and S3 is executed.

[0042] When C1=1, the fork lifting height H≥7000mm, C2 changes from large to small and the initial value of C2 is less than or equal to 3.5V, it indicates that the fork high position slow descent command is output and step S4 is executed;

[0043] When C1=1, the fork lifting height H < H 预 When C2 decreases from a large value to a small value and its initial value is greater than 3.5V, it indicates that a command for the forks to descend rapidly at a low position is output, and step S5 is executed.

[0044] When C1=1, the fork lifting height H<7000mm, C2 changes from large to small and the initial value of C2 is less than or equal to 3.5V, it indicates that the fork low position slow descent command is output and step S6 is executed.

[0045] Where: C1: descent switch signal, when C1=1 it means that the forks are in the descent state.

[0046] C2: Lifting / lowering potentiometer signal, its range is 0-5V. When the lifting / lowering handle is in the neutral position, the potentiometer signal C2 = 2.5V. When the lifting / lowering handle is pushed forward (forks lower), the potentiometer output voltage signal ranges from 2.5V to 5V. When the lifting / lowering handle is released, the C2 signal changes from 5V to 2.5V (C2 signal changes from large to small), indicating that a stop is requested during the forks lowering process. When the lifting / lowering handle is pulled back (forks raise), the potentiometer output voltage signal ranges from 2.5V to 0V. When the lifting / lowering handle is released, the C2 signal changes from 0V to 2.5V (C2 signal changes from small to large), indicating that a stop is requested during the forks raising process.

[0047] C3: Fork lifting height signal, its range is 0~5V. The fork lifting height H is positively correlated with C3, and 5V corresponds to the maximum fork lifting height H. max .

[0048] S3: The controller receives a command for the forks to descend rapidly from a high position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V1. The formula for the preset speed V1 is:

[0049] V1 = X0 ÷ t1, the unit is mm / s;

[0050] Where X0 represents the current opening degree of the descent proportional solenoid valve in mm, and t1 represents the closing time of the descent proportional solenoid valve when the forks descend rapidly from a high position;

[0051] X0=[(C2 初始 -2.5)÷2.5]×X max ,

[0052] X max : Maximum opening degree of the proportional solenoid valve, in mm;

[0053] t1=[(C2 初始 -2.5)÷2.5]×K1×K2×t0×[H max [×C3÷(5×7000)];

[0054] Among them, C2 初始 This indicates the potentiometer signal when the lifting / lowering handle is released. K1 represents the adjustment coefficient for the closing time of the proportional solenoid valve when the forks descend rapidly, with K1 being 2. K2 represents the adjustment coefficient for the closing time of the proportional solenoid valve when the forks descend from a high position, with K2 being 1.5. t0 represents the standard closing time of the proportional solenoid valve during descent, in seconds.

[0055] S4: The controller receives a command for the forks to descend slowly from their high position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V2. The formula for the preset speed V2 is:

[0056] V2 = X0 ÷ t2, the unit is mm / s;

[0057] Where t2 represents the closing time of the proportional solenoid valve when the forks are slowly descending from a high position.

[0058] t2=[(C2 初始 -2.5)÷2.5]×K3×t0×[H max [×C3÷(5×7000)];

[0059] Wherein, K3 represents the adjustment coefficient for the closing time of the proportional solenoid valve when the forks descend slowly, and K3 is 0.5;

[0060] S5: The controller receives a command for the forks to descend rapidly from their low position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V3. The formula for the preset speed V3 is:

[0061] V3 = X0 ÷ t3;

[0062] Where t3 represents the closing time of the solenoid valve for the descent ratio when the forks are rapidly descending from a low position.

[0063] t3=[(C2 初始 -2.5)÷2.5]×K1×t0×[H max [×C3÷(5×7000)];

[0064] S6: The controller receives a low-position slow descent command for the forks, and simultaneously the lifting and lowering handles are released. The controller then controls the descent proportional solenoid valve to close at a preset speed V4. The formula for the preset speed V4 is:

[0065] V4 = X0 ÷ t4;

[0066] t4 represents the closing time of the solenoid valve when the forks are slowly descending from a low position;

[0067] t4=[(C2 初始 -2.5)÷2.5]×K3×K4×t0×[H max [×C3÷(5×7000)];

[0068] K4 represents the adjustment coefficient for the closing time of the proportional solenoid valve when it is in a low-position descent, and K4 is set to 0.6.

[0069] Example 2:

[0070] The method steps in this embodiment are the same as those in Embodiment 1, except that K1 is 1, K2 is 1, K3 is 1, and K4 is 1.

[0071] Example 3:

[0072] The method steps in this embodiment are the same as those in Embodiment 1, except that K1 is 1.5, K2 is 1.3, K3 is 0.7, and K4 is 0.8.

Claims

1. A method for controlling the lowering of forks in a reach truck, characterized in that, The method steps are as follows: S1: Monitor the output signal C1 of the descent switch, the output signal C2 of the lifting and lowering handle potentiometer, and the fork lifting height signal C3. Execute step S2 based on the return value. S2: When C1=1, the fork lifting height H≥H 预 C2 decreases from a large value to a small value, and the initial value of C2 is greater than C2. 预 When C1=1, it indicates that the fork lifting height H≥H is output as a command for rapid descent from a high position, and step S3 is executed; when C1=1, the fork lifting height H≥H 预 C2 decreases from a large value to a small value, and the initial value of C2 is less than or equal to C2. 预 When C1=1, it indicates that the output command for slow descent of the forks from a high position is executed, and step S4 is performed; when C1=1, the fork lifting height H<H 预 C2 decreases from a large value to a small value, and the initial value of C2 is greater than C2. 预 When C1=1, it indicates that the output fork low position rapid descent command is executed, and step S5 is executed; when C1=1, the fork lifting height H<H 预 C2 decreases from a large value to a small value, and the initial value of C2 is less than or equal to C2. 预 When this occurs, it indicates that a command to slowly lower the forks at a low position is output, and step S6 is executed. S3: The controller receives a command for the forks to descend rapidly from a high position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V1. The formula for the preset speed V1 is: V1 = X0 ÷ t1; Where X0 represents the current opening degree of the descent proportional solenoid valve, and t1 represents the closing time of the descent proportional solenoid valve when the forks descend rapidly from a high position. t1=[(C2 初始 -2.5)÷2.5]×K1×K2×t0×[H max ×C3÷(5×7000)]; Among them, C2 初始 This indicates the potentiometer signal when the lifting / lowering handle is released; K1 represents the proportional solenoid valve closing time adjustment coefficient when the forks descend rapidly; K2 represents the proportional solenoid valve closing time adjustment coefficient when the forks descend from a high position; t0 represents the standard closing time of the proportional solenoid valve during descent; H... max Indicates the maximum lifting height of the forks; S4: The controller receives a command for the forks to descend slowly from their high position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V2. The formula for the preset speed V2 is: V2 = X0 ÷ t2; Where t2 represents the closing time of the proportional solenoid valve when the forks are slowly descending from a high position. t2=[(C2 初始 -2.5)÷2.5]×K3×t0×[H max ×C3÷(5×7000)]; Wherein, K3 represents the adjustment coefficient for the closing time of the proportional solenoid valve when the forks descend slowly; S5: The controller receives a command for the forks to descend rapidly from their low position. Simultaneously, the lifting and lowering handles are released. The controller then controls the lowering proportional solenoid valve to close at a preset speed V3. The formula for the preset speed V3 is: V3 = X0 ÷ t3; Where t3 represents the closing time of the solenoid valve for the descent ratio when the forks are rapidly descending from a low position. t3=[(C2 初始 -2.5)÷2.5]×K1×t0×[H max ×C3÷(5×7000)]; S6: The controller receives a low-position slow descent command for the forks, and simultaneously the lifting and lowering handles are released. The controller then controls the descent proportional solenoid valve to close at a preset speed V4. The formula for the preset speed V4 is: V4 = X0 ÷ t4; t4 represents the closing time of the solenoid valve when the forks are slowly descending from a low position; t4=[(C2 初始 -2.5)÷2.5]×K3×K4×t0×[H max ×C3÷(5×7000)]; K4 represents the adjustment coefficient for the closing time of the proportional solenoid valve when the valve is in a low-position descent.

2. The method for controlling the lowering of forks in a reach truck according to claim 1, characterized in that: In step S2, the fork lifting height H = H max ×C3÷5.

3. The method for controlling the lowering of forks in a reach truck according to claim 1, characterized in that: In step S2, C2 预 It is 3.5V.

4. The method for controlling the lowering of forks in a reach truck according to claim 1, characterized in that: In step S2, H 预 It is 7000mm.

5. The method for controlling the lowering of forks in a reach truck according to claim 1, characterized in that: X0 represents the current opening degree of the proportional solenoid valve, which is calculated as X0 = [(C2)]. 初始 -2.5)÷2.5]×X max ;where X max This indicates the maximum opening degree of the proportional solenoid valve.

6. The method for controlling the lowering of forks in a reach truck according to claim 1, characterized in that: In step S3, when the forks descend rapidly, the value range of the proportional solenoid valve closing time adjustment coefficient K1 is 1-2, and when the forks descend from a high position, the value range of the proportional solenoid valve closing time adjustment coefficient K2 is 1-1.

5.

7. The method for controlling the lowering of forks in a reach truck according to claim 1, characterized in that: In step S4, when the forks descend slowly, the value range of the proportional solenoid valve closing time adjustment coefficient K3 is 0.5-1.

8. The method for controlling the lowering of forks in a reach truck according to claim 1, characterized in that: When the valve is in a low position, the value range of the proportional solenoid valve closing time adjustment coefficient K4 is 0.5-1.

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