Deceleration control device, industrial vehicle, deceleration control method, and storage medium

Abstract

The present application provides a deceleration control device, an industrial vehicle, a deceleration control method, and a storage medium, which reduce the discomfort felt by an operator due to a deceleration operation in an uphill. The deceleration control device for an industrial vehicle includes a storage section that stores a prescribed torque threshold value, a speed calculation section, a torque calculation section, a difference calculation section, and a deceleration correction section. When a deceleration operation is performed, the speed calculation section calculates a target speed, and the torque calculation section calculates a torque command value. When the calculated torque command value exceeds the torque threshold value, the difference calculation section calculates a difference between the torque command value and the torque threshold value, and the deceleration correction section corrects the deceleration so that the calculated torque command value becomes below the torque threshold value, based on the calculated difference. The torque calculation section corrects the torque command value, and the motor operates based on the corrected torque command value, whereby the vehicle in the uphill decelerates at a deceleration that is higher than the deceleration based on gravity.

Description

TECHNICAL FIELD

[0001] The present application relates to a deceleration control device for an industrial vehicle, an industrial vehicle including the device, a deceleration control method, and a storage medium. BACKGROUND

[0002] As a travel control device of an industrial vehicle, for example, a travel control device described in Patent Literature 1 is known. This travel control device is a travel control device of an electric forklift including an accelerator lever, calculates a target travel speed in accordance with an operation amount (tilt angle) of the accelerator lever, and causes the forklift to travel at the calculated target travel speed. Therefore, this travel device calculates a torque command value by performing proportional integral (PI) control so that a deviation between the calculated target travel speed and a current travel speed is zero, and outputs the torque command value to a motor. This forklift keeps the acceleration constant regardless of travel resistance, an uphill, and the like by performing acceleration limitation on a flat road or torque up on an uphill.

[0003] In addition, in the existing travel device, as shown in Figure 6A , a target speed is calculated every prescribed period (for example, every 2 msec) on the basis of a prescribed deceleration corresponding thereto, and deceleration is performed to reach the target speed by performing torque control such as PI control. For example, in the case of the existing battery-powered forklift 100, when deceleration operation based on accelerator OFF is performed on a flat road, a negative torque command value is calculated to become a target speed corresponding to a prescribed deceleration, whereby the motor is switched from power running operation to regenerative operation, as shown in Figure 6B and Figure 7A . In addition, even when deceleration operation such as stepping on a brake pedal, steering (operation to switch to a direction opposite to a traveling direction) is performed, a target speed is calculated every prescribed period on the basis of a prescribed deceleration corresponding to each deceleration operation, and deceleration is performed to reach the target speed by performing torque control. Furthermore, in a case where a braking force generated by a regenerative brake is smaller than an indicated braking force, for example, as described in Patent Literature 2, braking by using a friction brake is performed in addition to the regenerative brake.

[0004] However, as shown in Figure 7B , in the case of deceleration in an uphill, a deceleration based on gravity according to a slope of the uphill road sometimes exceeds a prescribed deceleration, as shown in Figure 6C . In this case, the forklift calculates a torque command value to become the prescribed deceleration, and as a result, as shown in Figure 6B , unlike other travel roads, the motor is not switched to regenerative operation even by accelerator OFF, but is switched to power running operation, as shown in Figure 7BThe hill is climbed while the power running is performed at the same time. Thus, the operator feels the hill is climbed even though the deceleration operation is performed, and has a sense of discomfort with the operation. Especially, the cargo handling vehicle is different from the usual passenger car, and sometimes the power running torque becomes large due to the weight of the cargo to be carried, and the operator has a greater sense of discomfort. From the viewpoint of safety or operability, it is preferable that the sense of discomfort with the operation be small.

[0005] [Related Art Documents]

[0006] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Laid-Open No. 2012-90463

[0008] [Patent Document 2] Japanese Patent Laid-Open No. 2019-13116 SUMMARY

[0009] [Problems to be Solved by the Invention]

[0010] Therefore, the present application aims to provide a deceleration control device that can reduce a sense of discomfort of an operator due to a deceleration operation in an uphill, an industrial vehicle including the device, a deceleration control method, and a deceleration control program.

[0011] [Technical Means for Solving the Problems]

[0012] To solve the problems, the deceleration control device of the present application is a deceleration control device for an industrial vehicle,

[0013] The industrial vehicle includes a motor that drives a drive wheel and switches between a power running operation and a regenerative operation based on an input torque command value, a deceleration operation section including an accelerator, and a speed detection section that detects a travel speed, and the deceleration control device is characterized by comprising:

[0014] a storage section that stores a predetermined deceleration (hereinafter referred to as a "predetermined deceleration") and a predetermined torque threshold value corresponding to an operation amount (hereinafter referred to as a "deceleration operation amount") of the deceleration operation section;

[0015] a speed calculation section that calculates a target speed based on the predetermined deceleration when the deceleration operation is performed;

[0016] a torque calculation section that calculates a torque command value to eliminate a deviation between the detected travel speed and the calculated target speed;

[0017] a difference calculation section that calculates a difference between the torque command value and the torque threshold value when the calculated torque command value exceeds the torque threshold value; and

[0018] a deceleration correction unit that corrects a prescribed deceleration on the basis of the calculated difference so that the calculated torque command value becomes below a prescribed torque threshold value,

[0019] a speed calculation unit that corrects the target speed on the basis of the corrected deceleration,

[0020] a torque calculation unit that calculates a torque command value so as to eliminate a deviation between the detected travel speed and the corrected target speed,

[0021] a motor that operates on the basis of the corrected torque command value, whereby the industrial vehicle in the uphill is decelerated at a deceleration that is above the gravity-based deceleration.

[0022] The deceleration control device is preferably:

[0023] The deceleration operation unit further includes a steering lever,

[0024] The prescribed deceleration includes a prescribed deceleration corresponding to a steering operation.

[0025] The deceleration control device is preferably a deceleration control device characterized in that,

[0026] The prescribed torque threshold value further includes a prescribed torque threshold value corresponding to a steering operation.

[0027] The deceleration control device is preferably:

[0028] The deceleration operation unit further includes a brake pedal,

[0029] The prescribed deceleration includes a prescribed deceleration corresponding to a depression amount of the brake pedal.

[0030] The deceleration control device is preferably:

[0031] The prescribed torque threshold value further includes a prescribed torque threshold value corresponding to a depression amount of the brake pedal.

[0032] With regard to the deceleration control device, for example,

[0033] The industrial vehicle is a cargo handling vehicle.

[0034] To solve the problem, the industrial vehicle of the present application is characterized in that,

[0035] includes the deceleration control device.

[0036] To solve the problem, the deceleration control method of the present application is a deceleration control method for an industrial vehicle,

[0037] The industrial vehicle includes a motor that drives a drive wheel and switches between a power running operation and a regenerative operation based on an input torque command value, a plurality of deceleration operation sections including an accelerator, and a speed detection section that detects a travel speed, and the deceleration control method is characterized by comprising:

[0038] a predetermined torque threshold value is set in advance;

[0039] a target speed is calculated based on a predetermined deceleration corresponding to a deceleration operation amount when the deceleration operation is performed;

[0040] a torque command value is calculated based on the detected travel speed and the calculated target speed;

[0041] a difference between the calculated torque command value and the torque threshold value is calculated when the calculated torque command value exceeds the predetermined torque threshold value;

[0042] the deceleration is corrected based on the calculated difference so that the calculated torque command value becomes below the torque threshold value;

[0043] the target speed is corrected based on the corrected deceleration;

[0044] the torque command value is corrected based on the detected travel speed and the corrected target speed; and

[0045] the motor is caused to operate based on the corrected torque command value, whereby the industrial vehicle in the uphill is caused to decelerate at a deceleration that is higher than the deceleration based on gravity.

[0046] To solve the problem, the deceleration control program of the present application is a deceleration control program for an industrial vehicle,

[0047] a computer is caused to function as the deceleration control device.

[0048] [Effects of the Invention]

[0049] The deceleration control device, the industrial vehicle including the device, the deceleration control method, and the deceleration control program according to the present application can reduce the discomfort felt by an operator due to a deceleration operation in an uphill. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is a side view of an industrial vehicle according to an embodiment of the present application.

[0051] Figure 2 is a functional block diagram of the industrial vehicle shown in Figure 1

[0052] Figure 3 is a functional block diagram of the industrial vehicle shown in Figure 1 ​A graph showing the torque before and after the accelerator OFF of the industrial vehicle.

[0053] Figure 4 A graph showing each deceleration in traveling.

[0054] Figure 5 A graph showing the flow of the deceleration control device of the present application.

[0055] Figures 6A to 6C A graph showing the deceleration control of the related art, Figure 6A showing the prescribed deceleration based on the accelerator OFF, Figure 6B showing the torque before and after the accelerator OFF in each road surface traveling, Figure 6C showing the difference between the prescribed deceleration and the deceleration based on the gravity.

[0056] Figure 7A and Figure 7B A graph showing the deceleration control method of the forklift truck of the related art, Figure 7A showing the deceleration control method on the flat road, Figure 7B showing the deceleration control method on the uphill road.

[0057] [Explanation of symbols]

[0058] 1: forklift truck

[0059] 10: front wheel

[0060] 11: rear wheel

[0061] 12: vehicle body

[0062] 13: mast

[0063] 14: hydraulic cylinder

[0064] 15: fork

[0065] 16: driver's seat

[0066] 17: storage battery

[0067] 18: motor

[0068] 19: speed detection section

[0069] 20: deceleration operation section

[0070] 3: deceleration control device

[0071] 30: storage section

[0072] 31: speed calculation section

[0073] 32: torque calculation section

[0074] 33: difference calculation section

[0075] 34: deceleration correction unit

[0076] NA1: prescribed deceleration

[0077] NA2: corrected deceleration

[0078] Vo0: previous target speed

[0079] Vo1: target speed

[0080] Vo2: corrected target speed

[0081] Vn: running speed

[0082] T1: torque command value

[0083] T2: corrected torque command value

[0084] P: pallet

[0085] O: operator DETAILED DESCRIPTION

[0086] An embodiment of a deceleration control device, an industrial vehicle including the device, a deceleration control method, and a program according to the present application will be described below with reference to the drawings. In the present embodiment, the industrial vehicle is a battery counterbalanced forklift truck (corresponding to a "cargo handling vehicle" of the present application), but this is only an example, and the industrial vehicle of the present application is not limited to a forklift truck.

[0087] Figure 1 is a side view of the forklift truck 1. As shown in Figure 1 , the forklift truck 1 includes front and rear wheels 10, 11, a vehicle body 12, a pair of masts 13, a pair of forks 15, a driver's seat 16, a battery 17, and a motor 18 (see Figure 2 ).

[0088] The vehicle body 12 is disposed on the front and rear wheels 10, 11, and the pair of masts 13 extend upward and downward and are disposed in front of the vehicle body 12. The pair of forks 15 are configured to be raised and lowered along the masts 13 by extension and contraction of the hydraulic cylinders 14. The driver's seat 16 is disposed on top of the vehicle body 12. An operator O sits on the driver's seat 16 and operates a handle and the like, and performs a cargo handling work by lifting a pallet P with the forks 15.

[0089] The battery 17 is disposed substantially in the center of the vehicle body 12. In the present embodiment, the front wheels 10 are drive wheels, and a drive shaft is connected to the left and right front wheels 10 and the motor 18. The motor 18 is driven by battery power, and drives the front wheels 10 through the drive shaft by the driving torque thereof. In addition, the motor 18 switches between a power running operation and a regenerative operation based on an input torque command value.

[0090] As Figure 2 shown, the forklift 1 further includes a computer (deceleration control device 3), a speed detection section 19, and a deceleration operation section 20.

[0091] The computer is configured in the vehicle body 12, and includes a storage unit, a memory, and an arithmetic unit, not shown. An operating system (OS) and a deceleration control program are stored in the storage unit. The deceleration control program causes the computer to function as the deceleration control device 3. The deceleration control device 3 includes a storage section 30, a speed calculation section 31, a torque calculation section 32, a difference calculation section 33, and a deceleration correction section 34.

[0092] The speed detection section 19 is configured to detect the running speed Vn of the forklift 1. The speed detection section 19 can be provided to a drive shaft, for example, and detects the running speed Vn by detecting the rotational speed of the drive shaft. The detected running speed Vn is output to the speed calculation section 31. The method of detecting the running speed Vn is not particularly limited, and the speed detection section 19 can detect the running speed Vn by detecting the rotational speed of the motor 18, for example.

[0093] As Figure 1 shown, the deceleration operation section 20 includes an accelerator pedal, a direction lever, and a brake pedal. However, this is merely an example, and the deceleration operation section 20 of the present application is not limited thereto. For example, the deceleration operation section 20 can have an accelerator lever instead of the accelerator pedal. In this case, the accelerator lever can also have the function of the direction lever. Furthermore, the "accelerator" in the present application is a concept including both the accelerator pedal and the accelerator lever. Hereinafter, the accelerator pedal and the brake pedal will be referred to as "operation sections" at times.

[0094] The accelerator pedal and the brake pedal are depressed by the operator O, and the amounts of depression are output to the speed calculation section 31, respectively. Furthermore, the amounts of depression of the accelerator pedal and the brake pedal include a state in which the foot is removed from the accelerator pedal and the brake pedal, i.e., when the amount of depression is 0 (hereinafter referred to as "accelerator OFF").

[0095] The direction lever is a lever that switches the forward / reverse of the forklift 1. The forklift 1 is a battery counterbalanced forklift 1, and is configured such that, by depressing the accelerator pedal after the steering operation, a torque corresponding to the amount of depression is output to the drive wheels. The amount of operation of the direction lever is output to the speed calculation section 31.

[0096] The storage unit 30 stores multiple predetermined deceleration NA1s (hereinafter referred to as "predetermined deceleration NA1s") corresponding to each operation amount of the deceleration operation unit 20, as well as a torque threshold TL. The predetermined deceleration NA1s include, for example, a predetermined deceleration NA1 corresponding to the moment the accelerator is OFF. Furthermore, the predetermined deceleration NA1s include predetermined deceleration NA1s corresponding to steering operations and predetermined deceleration NA1s corresponding to the amount of braking pedal depressor input. Furthermore, the storage unit 30 also stores the function f, which will be described later.

[0097] As described below, the torque threshold TL is a predetermined threshold used when correcting for a specified deceleration NA1. The torque threshold TL can be set for each operating unit or can be set jointly for all operating units. When set for each operating unit, the torque threshold TL corresponding to the accelerator OFF is set to 0, the torque threshold TL corresponding to the steering is set to a negative torque, and the torque threshold TL corresponding to the brake pedal is set to a smaller negative torque. In this embodiment, the torque threshold TL is set to a value common to all operating units.

[0098] When the deceleration operation unit 20 performs a deceleration operation, the speed calculation unit 31 calculates the target speed Vo1 based on a predetermined deceleration NA1 corresponding to the deceleration operation amount. In this embodiment, as shown in equation (1), the target speed Vo1 is calculated by subtracting the first deceleration speed Vd1 corresponding to the predetermined deceleration speed NA1 from the previous target speed Vo0. However, this is only one example; for example, the target speed Vo1 can also be calculated by subtracting the first deceleration speed Vd1 from the detected travel speed Vn.

[0099] Equation (1)... Target velocity Vo1 = Previously calculated target velocity Vo0 - First deceleration velocity Vd1

[0100] Furthermore, if the calculated target speed Vo1 is less than 0, the target speed Vo1 is set to 0.

[0101] The torque calculation unit 32 calculates a torque command value T1 to eliminate the deviation between the travel speed Vn detected by the speed detection unit 19 and the target speed Vo1 calculated by the speed calculation unit 31. If the torque command value T1 calculated by the torque calculation unit 32 is below the torque threshold TL, it is output to the motor 18. The motor 18 operates based on the input torque command value T1.

[0102] like Figure 3 As shown, when the calculated torque command value T1 exceeds the torque threshold TL, the differential calculation unit 33 calculates the difference ΔT between the torque command value T1 and the torque threshold TL using, for example, the following formula (2). The calculated difference ΔT is then output to the deceleration correction unit 34.

[0103] Equation (2)... Difference ΔT = Calculated torque command value T1 - Torque threshold TL

[0104] The deceleration correction unit 34 corrects the specified deceleration NA1 based on the input difference ΔT, so that the torque command value T2 recalculated by the torque calculation unit 32 becomes below the torque threshold TL. The second deceleration speed Vd2 corresponding to the corrected deceleration NA2 can be calculated by the following formula (3). The calculated second deceleration speed Vd2 is output to the speed calculation unit 31.

[0105] Equation (3)... Second deceleration speed Vd2 = First deceleration speed Vd1 + f(difference ΔT)

[0106] The function f in equation (3) is used to increase the deceleration during uphill driving based on the difference ΔT between the torque command value T1 and the torque threshold TL when the torque command value T1 exceeds the torque threshold TL. In other words, function f is used to adjust the degree to which the target speed Vo1 is corrected based on the difference ΔT. As an example of function f, equation (3) can also be set as follows.

[0107] Second deceleration speed Vd2 = First deceleration speed Vd1 + (Differential ΔT × Gain G1 + Gain G2)

[0108] In addition, in this embodiment, the function f is stored and set separately for accelerator pedal operation, steering stick operation and brake pedal operation.

[0109] The speed calculation unit 31 corrects the target speed Vo1 based on the corrected deceleration NA2, for example, using the following formula (4). The corrected target speed Vo2 is then output to the torque calculation unit 32. However, this is only one example; for instance, the corrected target speed Vo2 can also be calculated by subtracting the second deceleration speed Vd2 from the detected travel speed Vn.

[0110] Equation (4)... Corrected target velocity Vo2 = Previously calculated target velocity Vo0 - Second deceleration velocity Vd2

[0111] The torque calculation unit 32 recalculates the torque command value T2 to eliminate the deviation between the detected travel speed Vn and the corrected target speed Vo2. For example... Figure 3 As shown, the calculated result is that the calculated torque command value T2 is less than the torque threshold TL. Furthermore, the motor 18 performs a regenerative operation based on the calculated torque command value T2, thus... Figure 4 As shown, the forklift 1 going uphill is decelerated by a deceleration NA2 that is greater than the deceleration based on gravity.

[0112] Reference Figure 5The flow of the deceleration control device 3 will be described. Further, in the present embodiment, the flow is repeated at a cycle of 2 msec. This cycle can be set to, for example, 1 msec to 5 msec.

[0113] (1) First, when the operator O performs a deceleration operation (S1), the speed calculating section 31 calculates a target speed Voi from a previous target speed Vo0 by subtracting a first deceleration speed Vd1 (S2).

[0114] (2) Next, the torque calculating section 32 calculates a torque command value T1 to eliminate a deviation between the running speed Vn and the target speed Voi (S3).

[0115] (3) Next, in a case where the calculated torque command value T1 exceeds the torque threshold TL (Yes in S4), the difference calculating section 33 calculates a difference AT, the deceleration correcting section 34 corrects the deceleration NA1 according to the difference AT and a function f, and the speed calculating section 31 calculates a target speed Vo2 from a previous target speed Voi by subtracting a second deceleration speed Vd2 corresponding to a deceleration NA2 (S5). In a case where the calculated torque command value T1 is lower than the torque threshold TL (No in S4), the flow shifts to S6.

[0116] (4) Next, in a case where the calculated target speed Vo2 (or Voi) is lower than 0 (Yes in S6), the target speed Vo2 is set to 0 (Voi becomes Vo2 = 0) (S7).

[0117] (5) Next, the torque calculating section 32 newly calculates a torque command value T2 to make a deviation between the detected running speed Vn and the target speed Vo2 be 0 (S8).

[0118] (6) Next, the motor 18 functions as a regenerative brake in accordance with the calculated torque command value T2 (T1), and the fork truck 1 decelerates by braking using the gravity and the regenerative brake (S9). Further, in a case where the torque command value T2 (T1) is 0, the fork truck 1 decelerates due to the gravity. In addition, in a case where the torque command value T2 (T1) is positive, the fork truck 1 accelerates. Figure 5 In S7 of the above, in a case where the target speed Voi is set to 0, the fork truck 1 stops in S9 of the above. Figure 5

[0119] ​According to the deceleration control method using the deceleration control device 3, when the operator O performs a deceleration operation in an uphill, the forklift 1 can be decelerated at a deceleration that is higher than the gravitational deceleration. Thus, the operator O can be less likely to feel uncomfortable when performing a deceleration operation in an uphill. Further, the deceleration control device 3 can decelerate at the predetermined deceleration NA1 corresponding to each deceleration operation in a flat road, a downhill, and a gentle uphill as described above, and thus the deceleration control in an uphill does not interfere with the sense of operation in other roads. In addition, the deceleration in an uphill can be adjusted by simply changing the torque threshold TL stored in the storage unit 30.

[0120] In the case where the slope is such that the gravitational deceleration exceeds the predetermined deceleration NA1, if only the power running is prevented and the motor 18 is not caused to perform the regenerative operation and it is desired to decelerate at the gravitational deceleration, the torque threshold TL is set to 0, and if the function f is adjusted, the torque command value T1 calculated by the torque calculation unit 32 is made to be 0 to decelerate. Further, if it is considered that the operator feels less uncomfortable when decelerating at a deceleration that exceeds the gravitational deceleration as long as the operator performs a deceleration operation, the forklift 1 can be decelerated at a deceleration that exceeds the gravitational deceleration by making the torque threshold TL less than 0, and the increase and decrease of the deceleration in this case can be adjusted by adjusting the function f.

[0121] Further, the deceleration control device 3 can adjust the deceleration in an uphill without detecting the degree of the slope. Thus, the forklift 1 does not need to have a detection unit that detects the degree of the slope.

[0122] The deceleration control device for an industrial vehicle, the industrial vehicle including the device, the deceleration control method, and the deceleration control program of the present application have been described above, but the present application is not limited to the embodiments described above. For example, the present application can be implemented by the following modified examples and the like.

[0123] The forklift 1 can also decelerate by using the torque generated by the friction brake in addition to the regenerative brake in the case where the maximum torque generated by the regenerative brake is lower than the torque command value T1 as in the related art. Further, as such a friction brake, an electromagnetic brake can be used, which can be configured to mechanically brake the motor 18 in a non-excitation state and release the brake in an excitation state. In addition, the friction brake can also be a drum brake or a disc brake that mechanically brakes a direct drive wheel of a hydraulic type, and is not particularly limited. Thus, the operator O can be less likely to feel uncomfortable when performing a deceleration operation in an uphill. Further, the deceleration control device 3 can decelerate at the predetermined deceleration NA1 corresponding to each deceleration operation in a flat road, a downhill, and a gentle uphill as described above, and thus the deceleration control in an uphill does not interfere with the sense of operation in other roads. In addition, the deceleration in an uphill can be adjusted by simply changing the torque threshold TL stored in the storage unit 30.

[0120] In the case where the slope is such that the gravitational deceleration exceeds the predetermined deceleration NA1, if only the power running is prevented and the motor 18 is not caused to perform the regenerative operation and it is desired to decelerate at the gravitational deceleration, the torque threshold TL is set to 0, and if the function f is adjusted, the torque command value T1 calculated by the torque calculation unit 32 is made to be 0 to decelerate. Further, if it is considered that the operator feels less uncomfortable when decelerating at a deceleration that exceeds the gravitational deceleration as long as the operator performs a deceleration operation, the forklift 1 can be decelerated at a deceleration that exceeds the gravitational deceleration by making the torque threshold TL less than 0, and the increase and decrease of the deceleration in this case can be adjusted by adjusting the function f.

[0121] Further, the deceleration control device 3 can adjust the deceleration in an uphill without detecting the degree of the slope. Thus, the forklift 1 does not need to have a detection unit that detects the degree of the slope.

[0122] The deceleration control device for an industrial vehicle, the industrial vehicle including the device, the deceleration control method, and the deceleration control program of the present application have been described above, but the present application is not limited to the embodiments described above. For example, the present application can be implemented by the following modified examples and the like.

[0123] The forklift 1 can also decelerate by using the torque generated by the friction brake in addition to the regenerative brake in the case where the maximum torque generated by the regenerative brake is lower than the torque command value T1 as in the related art. Further, as such a friction brake, an electromagnetic brake can be used, which can be configured to mechanically brake the motor 18 in a non-excitation state and release the brake in an excitation state. In addition, the friction brake can also be a drum brake or a disc brake that mechanically brakes a direct drive wheel of a hydraulic type, and is not particularly limited.

Claims

1. A deceleration control device that is a deceleration control device for an industrial vehicle, the industrial vehicle including a motor that drives a drive wheel and switches between a power running operation and a regenerative operation based on an input torque command value, a deceleration operation portion that includes an accelerator, and a speed detection portion that detects a travel speed, the deceleration control device characterized by comprising: a storage portion that stores a prescribed deceleration corresponding to an operation amount of the deceleration operation portion, that is, a deceleration operation amount, and a prescribed torque threshold value, wherein the torque threshold value is set to be not more than 0; a speed calculation portion that calculates a target speed based on the prescribed deceleration when a deceleration operation is performed; a torque calculation portion that calculates the torque command value so as to eliminate a deviation between the detected travel speed and the calculated target speed; a difference calculation portion that calculates a difference between the calculated torque command value and the torque threshold value in a case where the calculated torque command value exceeds the torque threshold value; and a deceleration correction portion that corrects the prescribed deceleration based on the calculated difference so that the calculated torque command value becomes not more than the torque threshold value, the speed calculation portion correcting the target speed based on the corrected deceleration, the torque calculation portion calculating the torque command value so as to eliminate a deviation between the detected travel speed and the corrected target speed, and the motor operating based on the corrected torque command value, whereby the industrial vehicle in an uphill is decelerated at a deceleration that is not less than a deceleration based on gravity.

2. The deceleration control device according to claim 1, characterized in that the deceleration operation portion further includes a direction lever, and the prescribed deceleration includes a prescribed deceleration corresponding to a steering operation.

3. The deceleration control device according to claim 2, characterized in that the prescribed torque threshold value further includes a prescribed torque threshold value corresponding to the steering operation.

4. The deceleration control device according to any one of claims 1 to 3, characterized in that the deceleration operation portion further includes a brake pedal, and the prescribed deceleration includes a prescribed deceleration corresponding to a depression amount of the brake pedal.

5. The deceleration control device according to claim 4, characterized in that the prescribed torque threshold value further includes a prescribed torque threshold value corresponding to the depression amount of the brake pedal.

6. The deceleration control device according to any one of claims 1 to 3, characterized in that the industrial vehicle is a cargo handling vehicle. including: the deceleration control device according to any one of claims 1 to 6.

8. A deceleration control method that is a deceleration control method for an industrial vehicle, the industrial vehicle including a motor that drives a drive wheel and switches between a power running operation and a regenerative operation based on an input torque command value, a plurality of deceleration operation portions that include an accelerator, and a speed detection portion that detects a travel speed, the deceleration control method characterized by comprising: presetting a prescribed torque threshold value, wherein the torque threshold value is set to be not more than 0; ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7. An industrial vehicle characterized by, ​ ​ ​ ​ When the deceleration operation is performed, a target speed is calculated based on a prescribed deceleration corresponding to a deceleration operation amount; a torque command value is calculated based on the detected travel speed and the calculated target speed; when the calculated torque command value exceeds the prescribed torque threshold value, a difference between the torque command value and the torque threshold value is calculated; the deceleration is corrected based on the calculated difference so that the calculated torque command value becomes below the torque threshold value; the target speed is corrected based on the corrected deceleration; the torque command value is corrected based on the detected travel speed and the corrected target speed; and the motor is caused to operate based on the corrected torque command value, whereby the industrial vehicle in the uphill is caused to decelerate at a deceleration that is above the gravity-based deceleration.

9. A storage medium, characterized by a deceleration control program for the industrial vehicle is stored, the deceleration control program causes a computer to function as the deceleration control device according to any one of claims 1 to 6.

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