JP2001146400A - Control device of forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To travel by obtaining acceleration according to an accelerator quantity until a traveling speed of a car reaches a maximum speed, and restrict the traveling speed to the maximum speed or less when the traveling speed of the car exceeds the maximum speed. SOLUTION: A traveling speed of a car body is arithmetically operated from a vehicle speed detecting value obtained by a vehicle speed sensor, a comparison operation is performed on the traveling speed obtained by a vehicle speed operation part and a maximum speed set by a setting part by a comparison operation part (S1 to 55), and when the traveling speed is not more than the maximum speed as a result of comparison by the comparison operation part, a motor output command value for imparting acceleration in proportion to an accelerator quantity obtained by an accelerator detecting part to the car body is arithmetically operated by a control part (S6), and when the traveling speed becomes larger than the maximum speed, the motor output command value for restricting the traveling speed to the maximum speed or less is arithmetically operated by the control part (S8, S9).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift control device which uses a battery mounted on the body of a forklift as a drive source and drives a traveling motor by the output of the battery.

[0002]

2. Description of the Related Art As one of traveling control of a forklift, there is a control for accelerating a vehicle by depressing an accelerator pedal. According to this traveling control, the speed of the vehicle increases even if the accelerator pedal is continuously depressed at a certain angle. That is, just because the accelerator pedal is continuously depressed at a certain depressed amount does not mean that a speed corresponding to the depressed amount is obtained, and the difference in the depressed amount of the accelerator pedal is controlled as a difference in acceleration.

According to this, it is considered that the vehicle is likely to accelerate indefinitely by depressing the accelerator pedal. However, in actual running of the vehicle, the vehicle must be balanced by the running resistance of the vehicle due to the frictional resistance of the tires, air resistance and other resistances. And the vehicle can run at a constant speed. And
By setting the motor output command value when the accelerator pedal is fully depressed to a command value balanced with the maximum speed of the vehicle, the maximum speed of the vehicle can be set.

This control method has the advantages that the running speed of the vehicle can be adjusted according to the amount of depression of the accelerator pedal, the forklift can be run with a driving feeling close to that of a passenger car, and the maximum speed can be limited as described above. There is. However, according to this traveling control, limiting the maximum speed is effective when the vehicle travels on a flat road,
If the car goes down a slope, it will be invalid. That is,
When the vehicle goes down a hill, the vehicle gradually accelerates regardless of the amount of depression of the accelerator pedal, and exceeds the set maximum speed.

The above-mentioned traveling control is a traveling control in which the depression amount of the accelerator pedal is proportional to the acceleration amount of the vehicle. In addition, there is a traveling control in which the depression amount of the accelerator pedal is proportional to the speed. In other words, the control is to output a traveling speed according to the depression amount of the accelerator pedal. When the accelerator pedal is continuously depressed at a certain angle, the vehicle travels at a speed corresponding to the depression amount.

According to this control, it is possible to control the traveling speed of the vehicle to be equal to or lower than the maximum speed by setting the traveling speed when the accelerator pedal is fully depressed to the maximum speed. Even when the vehicle goes down a hill, there is an advantage that the vehicle does not accelerate because the maximum speed is determined according to the depression amount of the accelerator pedal. However, according to this traveling control, the traveling speed is in accordance with the amount of depression of the accelerator pedal, so that the traveling feeling is different from the driving feeling of a passenger car (the driving feeling of traveling in a low-speed gear of a passenger car), and there is a problem that it is difficult to drive if not used. When the accelerator pedal is released, the amount of depression of the accelerator pedal becomes zero, and the corresponding traveling speed becomes zero, and the vehicle suddenly stops (the motor is suddenly regenerated).

That is, if the accelerator pedal is not depressed, the running speed of the car can be limited to the maximum speed or less, but the driving feeling of a passenger car is that a car running on a flat road descends on a slope at that speed. In such cases, the acceleration is naturally applied.Therefore, it is common for the operator to release the accelerator pedal when the acceleration is large, or to release the accelerator pedal when the acceleration is large, and the operator releases the accelerator pedal with the driving feeling of this passenger car. If this happens, the car will suddenly stop on a downhill, etc., and the operator himself is in danger.Because the forklift has a load loaded in front, there is a risk that the load collapses, and the forklift travels in a narrow passage. In many cases, the collapsed load could damage surrounding objects.

[0008]

As described above, in normal operation of a forklift, the acceleration according to the amount of depression of the accelerator pedal is maintained until the vehicle reaches the maximum speed (that is, from zero speed to the maximum speed). If the vehicle speed is higher than the maximum speed, it is desirable that the vehicle can run with the vehicle speed limited to the maximum speed or less. However, in the above-described example, the operator can travel while obtaining acceleration according to the accelerator amount by adjusting the accelerator pedal by himself / herself, but when the vehicle accelerates on a downhill road or the like, the traveling speed cannot be limited to the maximum speed or less. .

On the other hand, in the example described above, the vehicle can travel with the maximum speed of the vehicle limited even on a downhill or the like, but since the traveling speed is in accordance with the amount of depression of the accelerator pedal, the vehicle travels until the vehicle reaches the maximum speed. (That is, from zero speed to maximum speed)
The driving feeling of the vehicle is different from the driving feeling of a passenger car, and there is a risk that the car will stop suddenly when the accelerator pedal is released even when descending a slope.

Therefore, an object of the present invention is to provide a vehicle that can travel with an acceleration corresponding to the accelerator amount until the vehicle speed reaches the maximum speed, and to reduce the vehicle speed when the vehicle speed exceeds the maximum speed. An object of the present invention is to limit the maximum speed to a value lower than the maximum speed and to perform the control for limiting the maximum speed irrespective of whether the accelerator is on or off.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an accelerator for detecting an accelerator amount in a forklift control device for driving a traveling motor by supplying electric power from a battery mounted on a vehicle body. A detection unit, a vehicle speed sensor that detects a vehicle speed detection value corresponding to the vehicle speed, a vehicle speed calculation unit that calculates the vehicle speed based on the vehicle speed detection value obtained by the vehicle speed sensor, and a maximum speed of the vehicle body A comparison unit that compares the running speed obtained by the vehicle speed calculation unit with the maximum speed set by the setting unit; and a comparison result obtained by the comparison calculation unit. When the speed is equal to or less than the maximum speed, a motor output command value for giving an acceleration proportional to the accelerator amount obtained by the accelerator detection unit to the vehicle body is calculated, and the traveling speed is set to the maximum speed. When increased Ri is characterized by comprising a control unit for calculating a motor output command value which limits the travel speed below the maximum speed.

According to such a configuration, the vehicle can travel with the acceleration corresponding to the accelerator amount at the traveling speed up to the maximum speed of the vehicle, and when the vehicle becomes higher than the maximum speed, the traveling speed is increased to the maximum. Speed can be limited below. As a result, in normal driving, traveling control that gives the driving feeling of a passenger car can be performed, and when the vehicle body becomes higher than the maximum speed, such as when going down a slope, the traveling speed is limited to the maximum speed or less to maintain safety. Traveling control can be performed.

Further, the present invention provides a control device for a forklift for driving a traveling motor by supplying power from a battery mounted on a vehicle body, an accelerator detecting unit for detecting ON / OFF of an accelerator and an accelerator amount, A vehicle speed sensor that detects a vehicle speed detection value corresponding to the traveling speed, a vehicle speed calculation unit that calculates the traveling speed of the vehicle body from the vehicle speed detection value obtained by the vehicle speed sensor, and a setting unit that sets the maximum speed of the vehicle body A comparison operation unit that performs a comparison operation between the traveling speed obtained by the vehicle speed operation unit and the maximum speed set by the setting unit; and a comparison result obtained by the comparison operation unit, wherein the traveling speed is equal to or less than the maximum speed. When, the motor output command value that gives the vehicle body an acceleration proportional to the accelerator amount obtained in the accelerator detection unit, the travel speed is greater than the maximum speed When Tsu, accelerator amount of ON, O
A control unit for calculating a motor output command value for limiting the running speed to a maximum speed or less regardless of the FF.

According to such a configuration, the vehicle can travel with the acceleration corresponding to the accelerator amount at the traveling speed up to the maximum speed of the vehicle, and when the vehicle becomes higher than the maximum speed, the traveling speed is increased to the maximum. Speed can be limited below. As a result, in normal driving, traveling control that gives the driving feeling of a passenger car can be performed, and when the vehicle body becomes higher than the maximum speed, such as when going down a slope, the traveling speed is limited to the maximum speed or less to maintain safety. In addition to performing the traveling control, the traveling speed can be limited to the maximum speed or less regardless of whether the accelerator is on or off. Thereby, even when the operator releases the accelerator pedal on a slope or the like, the traveling speed can be limited to the maximum speed or less,
On hills and the like, it is possible to improve the safety by limiting the traveling speed while allowing the passenger to feel like releasing or releasing the accelerator pedal.

According to the present invention, there is provided a forklift control device for driving a traveling motor by supplying electric power from a battery mounted on a vehicle body. A vehicle speed sensor that detects a corresponding vehicle speed detection value, a vehicle speed calculation unit that calculates a running speed of the vehicle body from the vehicle speed detection value obtained by the vehicle speed sensor, a setting unit that sets a maximum speed of the vehicle body, and the vehicle speed A comparison operation unit that compares and calculates the traveling speed obtained by the operation unit and the maximum speed set by the setting unit;
As a result of the comparison by the comparison operation unit, when the traveling speed becomes higher than the maximum speed, the accelerator is turned on and off.
And a controller for calculating a motor output command value for limiting the running speed to a maximum speed or less.

According to such a configuration, the accelerator O
The running speed can be limited to the maximum speed or less regardless of N and OFF. Thereby, even when the operator releases the accelerator pedal on a slope or the like, it is possible to limit the traveling speed to the maximum speed or less, while allowing the accelerator pedal to be loosened or released on a slope or the like while driving,
It is possible to improve the safety by limiting the traveling speed.

Further, the present invention comprises a rotation detecting section for detecting the number of rotations of the motor, and a deriving section for deriving the speed and acceleration of the vehicle body from values detected by the rotation detecting section.
The control unit derives the speed and acceleration of the vehicle body from the rotation speed of the motor by the rotation detection unit, and calculates the output command value based on the derived speed and acceleration.

According to such a configuration, since the output command value of the motor is calculated based on the speed and acceleration of the vehicle body during traveling, the motor is controlled in accordance with the calculated output command value, so that the motor of the vehicle body is controlled. The running speed can be limited to a set value or less.

The present invention further comprises a switching section for setting the transmission means for transmitting the driving force of the motor to the wheels to either forward or reverse or a neutral state, and the control section includes a switching section for switching the switching section. The output command value in the forward direction and the output command value in the reverse direction are calculated according to the state.

According to such a configuration, the output command value of the motor in consideration of the rotation direction of the motor is calculated depending on whether the vehicle body is traveling forward or backward, and whether the vehicle is traveling forward or backward. The speed can be limited to less than the maximum speed by the setting unit.

Further, the present invention is characterized in that the motor is an induction motor, and the DC power output from the battery is converted into AC power by an inverter to supply power to the induction motor.

According to such a configuration, the control signal from the inverter to the induction motor may be controlled so as to be an output command value calculated by the control unit. However, on a slope, the induction motor can be regeneratively controlled to limit the traveling speed of the forklift to a maximum speed or less.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment in which the present invention is applied to a counterbalance type forklift.
This will be described with reference to FIG. 1 is a schematic diagram of a forklift according to an embodiment of the present invention, FIG. 2 is a partial connection diagram, FIG. 3 is a block diagram of a control device, and FIGS. 4 and 5 are flowcharts for explaining operations. .

As shown in FIG. 1, the forklift travels by supplying power to a traveling motor 3 by a battery 2 mounted on a vehicle body 1. At this time, the transmission means (not shown) for transmitting the driving force of the traveling motor 3 to the wheels is operated by operating a directional lever (or a directional switch) 4 for setting one of forward and backward or a neutral state. Switching to the neutral state when the means is moving forward or backward and when parking is performed, and steering is performed by the steering wheel 5. In FIG. 1, reference numeral 6 denotes a mast provided on a front portion of the vehicle body 1, reference numeral 7 denotes a lift bracket provided on the mast 6, reference numeral 8 denotes a pair of forks provided on the lift bracket 7, and reference numeral 9 denotes an accelerator pedal.

The traveling motor 3 is constituted by an AC motor, for example, a three-phase induction motor. As shown in FIG. 2, when the main switch 11 is turned on, the output DC power of the battery 2 is smoothed by the smoothing capacitor 12. At the same time, the power is converted to AC power by a three-phase bridge inverter 13 formed by connecting six field-effect transistors T1 to T6 in full bridge, and is supplied to the three-phase induction motor 14.

Next, the structure of the control device will be described. As shown in FIG. 3, a detection signal from an accelerator detection unit (not shown) proportional to the amount of depression of an accelerator pedal 9 is analog / digital (A / D). D) The signal is converted into a digital signal by the conversion unit 21, and the ON / OFF of the accelerator and the depression amount are detected by a CPU described later. Further, as shown in FIG. 2, a rotation detecting unit 15 composed of a rotary encoder is provided on a rotating shaft of the induction motor 14, and an output pulse from the rotation detecting unit 15 is counted by a counter 22. From the count value, the number of rotations of the induction motor 14 is detected by a CPU described later.

Further, the switching state of the directional lever 4 as a switching unit for setting the transmission means (not shown) for transmitting the driving force of the induction motor 14 to the wheels to either the forward or backward or the neutral state is parallel. Input unit (PI)
The signal is input to a CPU, which will be described later, via 23, and the CPU determines whether the directional lever 4 is set to the forward direction, the backward direction, or the neutral state.

Further, for example, a 5k
a setting unit 24 for setting the maximum speed in three stages such as m / h, 10 km / h, and 15 km / h;
The maximum speed set by the switch operation of the setting unit 24 is fetched by a CPU, which will be described later, and the rotation of the induction motor 14 is controlled so that the actual traveling speed is lower than the maximum speed by the setting unit 24.

Data such as the amount of depression of the accelerator pedal 9, the number of rotations of the motor, the switching state of the directional lever 4, and the maximum speed by the setting unit 24 are represented by R
According to a predetermined control program temporarily stored in the AM 25 and stored in the ROM 26 in advance, the CPU 27
Pulse width modulation (PWM)
on) A PWM control pulse is output from the pulse output unit 28 to the control terminals of the transistors T1 to T6 of the inverter 13, the output current of the induction motor 14 is controlled, and power running control or regenerative control is performed. .

The CPU 27 calculates and derives the traveling speed and acceleration of the vehicle body 1 from the motor rotation speed (vehicle speed detection value) detected by the rotation detecting unit 15 as a vehicle speed sensor during traveling. Based on the speed and the acceleration, an output command value of the induction motor 14 is calculated by proportional differential (PD) control in order to limit the running speed to the maximum speed set by the setting unit 24 or less. At this time, CPU2
7, the traveling speed and the maximum speed of the installation unit 24 are compared and calculated. For example, when the maximum speed is set to 15 km / h, the induction motor 14 is controlled so that the traveling speed does not exceed 15 km / h. The output command value is calculated, and based on the calculated output command value, the PWM pulse output unit 28 is controlled to control the rotation speed of the induction motor 14.

At this time, the CPU 27 simultaneously derives the positive and negative directions of the speed depending on whether the self-running direction of the vehicle body 1 is forward or backward, and according to the direction of the speed, the CPU 27 The output command value of the induction motor 14 in the forward rotation direction (when moving forward) or in the reverse rotation direction (when moving backward) may be calculated.

The CPU 27 calculates the output command value by setting the maximum speed by the setting unit 24 to Vs, the derived traveling speed to V, the acceleration to G, and the gain (coefficient) of the control system to k.
Assuming that the output command value Mf of the induction motor 14 when the traveling direction is forward and the output command value Mb of the induction motor 14 when the traveling direction is backward, Mf = k1 × (V−Vs) + k2 × G (forward) Mb = −k1 × (V−Vs) −k2 × G (in the case of receding). Here, the first term on the right side of each of the above equations represents a proportional (P) control component in proportional differential (PD) control, and the second term on the right side represents a differential (D) control component.

Next, the operation will be described with reference to the flowchart of FIG.

As shown in FIG. 4, the CPU 27 first initializes the RAM 25 and the like (S25).
1) A signal proportional to the amount of depression of the accelerator pedal is fetched from the accelerator pedal detector (S2), and PI23
, The switching state of the directional lever 4 is input (S3), the count value of the counter 22 is fetched, and the running speed V and acceleration G of the vehicle body 1 at that time are calculated from the fetched count value. (S4).
The calculation of the traveling speed V by the CPU 27 corresponds to a vehicle speed calculation unit.

Subsequently, it is determined whether or not the magnitude of the traveling speed V calculated in step S4 is smaller than the maximum speed Vs (S5). If the result of this determination is YES, the traveling speed V is limited. Since it can be determined that there is no need to apply, normal traveling control processing is performed (S6), and thereafter, the process proceeds to step S10 described later. And CPU1
7 corresponds to the comparison operation unit.

Here, the normal running control processing in step S6 is, as shown in FIG. 5, a motor output command value during normal running by multiplying a predetermined gain (coefficient) by an accelerator pedal depression amount. Calculation process (S20)
It is. That is, the depression amount of the accelerator pedal 9 is detected by the accelerator pedal detection unit, and the output command value of the induction motor 14 in proportion to the depression amount of the accelerator pedal 9 is calculated. Equivalent to.

On the other hand, if the result of the determination in step S5 is NO, it can be determined that the current traveling speed of the forklift should be limited to the maximum speed or more, and the switching state of the directional lever 4 is set to forward or backward. Is determined (S7), and when it is determined that the vehicle is moving forward, the output command value Mf of the induction motor 14 is calculated according to the expression of the output command value Mf of the induction motor 14 in the case of the forward movement (S8). If it is determined in step S7 that the vehicle is retreating, the output command value Mb of the induction motor 14 is calculated according to the expression of the output command value Mb of the induction motor 14 in the case of the retreat described above (S9). Such calculation processing of the output command value of the induction motor 14 by the CPU 27 when the traveling speed is equal to or higher than the maximum speed also corresponds to the control unit.

Then, the above steps S6, S8, S
After the process of step 9, the process proceeds to the next step S10, where the CPU 27 outputs the PWM pulse output unit 2 based on the output command value of the induction motor 14 calculated in step S6.
8 is controlled, and the number of revolutions of the induction motor 14 is controlled so as to have a speed corresponding to the depression amount of the accelerator pedal (S10).

On the other hand, in step S8, the output of the induction motor 14 becomes Mf, and in step S9, the output of the induction motor 14 becomes Mb.
The PWM pulse output unit 28 is controlled by the CPU 27,
The rotation speed of the induction motor 14 is controlled so that the speed of the vehicle body 1 becomes equal to or less than the maximum speed of 15 km / h (S
10) Then, the process returns to step S2.

According to such a control procedure, even if the forklift depresses the accelerator pedal strongly, the maximum traveling speed of the forklift is limited to the maximum speed of, for example, 15 km / h set by the setting unit 24. In this case, when the depression of the accelerator pedal is small and the actual traveling speed has not reached the maximum speed, the induction motor 14 is in the power running control state.

Even if the accelerator pedal is depressed in this way and the vehicle shifts from a flat road to a slope, the forklift traveling speed when descending the slope is the maximum speed of 15 km.
/ H. As described above, when the traveling speed is limited to the maximum speed or less, the induction motor 14 is in the regeneration control state.

Therefore, according to the above-described embodiment, the traveling speed of the forklift is limited to the maximum speed even when descending on a slope while the accelerator is depressed. There is no risk of load collapse, no extra braking distance is required for braking, and it is possible to go down a slope at a safe speed.

In the above-described embodiment, the motor output command value Mf in the case of forward movement and the motor output command value Mf in the case of backward movement are determined in step S7 of FIG. 4 by determining whether the switching state of the directional lever 4 is forward or backward. The output command value Mb is calculated. In step S4, it is determined whether the vehicle is moving forward or backward based on the direction of the speed derived from the count value of the counter. , And the motor output command value Mb in the case of retreat may be calculated.

In the above-described embodiment, the traveling speed of the forklift is limited to the maximum speed set by the setting unit 24, but is limited to a speed slightly higher than the maximum speed (for example, the maximum speed +1 km / h). Needless to say, it may be done.

Further, in the above-described embodiment, the setting unit 24
Has been described in which the maximum speed is set in three stages, but it goes without saying that the maximum speed may be set in two stages or four or more stages.

In the above embodiment, the case where the induction motor 14 is used has been described. However, the present invention can be similarly applied to a forklift using a DC motor as a power source. It is possible to obtain the same effect as the above embodiment.

Further, in the above-described embodiment, a case has been described in which the present invention is provided for a counterbalance type forklift. However, in addition to the above-described counterbalance type to which the present invention can be applied, a reach type forklift such as a reach type forklift can be used. It is needless to say that the present invention can be applied to a forklift that can use a motor as a power source. In this case, the same effect as that of the above-described embodiment can be obtained.

The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.

[0049]

As described above, according to the first aspect of the present invention, at the running speed until the vehicle reaches the maximum speed, the vehicle can run with the acceleration according to the accelerator amount, and the vehicle can operate at the maximum speed. When it becomes larger, the traveling speed can be limited to the maximum speed or less. As a result, in normal traveling, traveling control that gives the driving feeling of a passenger car can be performed, and when the vehicle becomes higher than the maximum speed, such as when going down a hill, the traveling speed is limited to the maximum speed or less to maintain safety. Traveling control can be performed.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the traveling speed can be limited to a maximum speed or less regardless of whether the accelerator is on or off. Accordingly, even when the operator releases the accelerator pedal on a slope, the traveling speed can be limited to the maximum speed or less. On a slope, the driver can release the accelerator pedal or release the accelerator pedal, and the driving speed can be reduced. Can be improved to improve safety.

According to the third aspect of the invention, the traveling speed can be limited to the maximum speed or less regardless of whether the accelerator is on or off. Accordingly, even when the operator releases the accelerator pedal on a slope, the traveling speed can be limited to the maximum speed or less. On a slope, the driver can release the accelerator pedal or release the accelerator pedal, and the driving speed can be reduced. Can be improved to improve safety.

According to the fourth aspect of the present invention, the output command value of the motor is calculated based on the speed and acceleration of the vehicle body during traveling, so that the motor is controlled in accordance with the calculated output command value. Thus, the speed at which the vehicle body runs by itself can be limited to a set value or less.

According to the fifth aspect of the present invention, a motor output command value is calculated in consideration of the rotation direction of the motor, depending on whether the vehicle body is traveling forward or backward, and In either case, the speed can be limited to the maximum speed or less by the setting unit.

According to the sixth aspect of the present invention, the control signal from the inverter to the induction motor may be controlled so that the output command value is calculated by the control unit. The running speed of the forklift can be limited to a maximum speed or less by controlling the power of the induction motor and controlling the regeneration of the induction motor on a slope.

[Brief description of the drawings]

FIG. 1 is a schematic view of a forklift according to an embodiment of the present invention.

FIG. 2 is a connection diagram of a control device according to an embodiment of the present invention.

FIG. 3 is a block diagram of a control device according to the embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the embodiment of the present invention;

FIG. 5 is a flowchart for explaining the operation of the embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 vehicle body 2 battery 4 directional lever (switching unit) 9 accelerator pedal 13 three-phase bridge inverter 14 three-phase induction motor 15 rotation detection unit (vehicle speed sensor) 24 setting unit 27 CPU (vehicle speed calculation unit, comparison calculation unit, control unit)

Claims (6)

[Claims] 1. A control device for a forklift for driving a traveling motor by supplying power from a battery mounted on a vehicle body, an accelerator detection unit for detecting an accelerator amount, and a vehicle speed detection value corresponding to a traveling speed of the vehicle body. A vehicle speed sensor, a vehicle speed calculation unit that calculates a running speed of the vehicle body from a vehicle speed detection value obtained by the vehicle speed sensor, a setting unit that sets the maximum speed of the vehicle body, and a vehicle speed calculation unit that obtains the maximum speed of the vehicle body. A comparison operation unit that performs a comparison operation between a traveling speed and a maximum speed set by the setting unit; and a comparison result obtained by the comparison operation unit. A motor output command value for giving an acceleration proportional to the accelerator amount given to the vehicle body is calculated, and when the traveling speed is higher than the maximum speed, the traveling speed is equal to or less than the maximum speed. A control unit for calculating a motor output command value to limit the motor output command value. 2. A control device for a forklift for driving a traveling motor by supplying electric power from a battery mounted on a vehicle body, comprising: an accelerator detecting unit for detecting ON / OFF of an accelerator and an accelerator amount; A vehicle speed sensor for detecting a vehicle speed detection value to be calculated; a vehicle speed calculation unit for calculating a running speed of the vehicle body from the vehicle speed detection value obtained by the vehicle speed sensor; a setting unit for setting the maximum speed of the vehicle body; A comparison operation unit that performs a comparison operation between the traveling speed obtained by the unit and the maximum speed set by the setting unit; and, as a result of the comparison by the comparison operation unit, when the traveling speed is equal to or less than the maximum speed, Calculate a motor output command value that gives the vehicle body an acceleration proportional to the accelerator amount obtained by an accelerator detection unit, and when the traveling speed is greater than the maximum speed, A control unit for calculating a motor output command value for limiting the traveling speed to a maximum speed or less regardless of whether the accelerator amount is ON or OFF. 3. A control device for a forklift for driving a traveling motor by supplying electric power from a battery mounted on a vehicle body, an accelerator detector for detecting ON / OFF of an accelerator, and a vehicle speed detection corresponding to a traveling speed of the vehicle body. A vehicle speed sensor for detecting a value of the vehicle speed, a vehicle speed calculation unit for calculating a running speed of the vehicle body from a vehicle speed detection value obtained by the vehicle speed sensor, a setting unit for setting a maximum speed of the vehicle body, and a vehicle speed calculation unit. A comparison operation unit that performs a comparison operation between the obtained traveling speed and the maximum speed set by the setting unit; and, as a result of the comparison by the comparison operation unit, when the traveling speed becomes greater than the maximum speed, ON, OFF
A control unit for calculating a motor output command value for limiting the traveling speed to a maximum speed or less. 4. A control device comprising: a rotation detection unit configured to detect a rotation speed of the motor; and a derivation unit configured to derive a speed and an acceleration of the vehicle body from values detected by the rotation detection unit. 4. The method according to claim 1, wherein the speed and acceleration of the vehicle body are derived from the number of rotations of the motor, and the output command value is calculated based on the derived speed and acceleration. The control device of the forklift described. 5. A switching unit for setting a transmission means for transmitting the driving force of the motor to wheels to one of forward and backward or a neutral state, wherein the control unit responds to a switching state of the switching unit. 5. The control device for a forklift according to claim 1, wherein the output command value in the forward direction and the output command value in the reverse direction are respectively calculated. 6. The motor according to claim 1, wherein the motor is an induction motor, and the DC power output from the battery is converted into AC power by an inverter and supplied to the induction motor. 6. The control device for a forklift according to any one of claims 5 and 6.