JPH11217200A - Traveling control device or forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the load collapse by the vibration of a load and the drop of the load by controlling a drive means according to a predetermined prescribe control means by which the load collapse is restrained, when the judge signal of a bad road is outputted. SOLUTION: CPU 21 judges whether the running road surface is bad or not based on the detection signal of a pressure sensor 10 and calculates the weight of a load placed on a fork. It is judged to a bad road when the value is changed by a standard frequency θ0 or more. When a CPU 21 does not judge that it is a bad road, the drive motor 7 is controlled so as to be a speed in response to the operation amount of an acceleration pedal. When CPU 21 judges it is a bad road, the drive motor 7 is controlled according to the predetermined prescribed control condition by which the load collapse can be prevented, regardless of the operation amount of the acceleration pedal. A CPU 21 controlls the drive motor 7 so that the car speed may be a prescribed low speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift traveling control device.

[0002]

2. Description of the Related Art In a battery forklift using a motor powered by a battery as a driving means of driving wheels,
In general, a method of controlling a traveling motor by chopper is employed as a traveling speed control method. In this chopper control, the duty ratio (conductivity) of the chopper signal is determined in advance based on the operation amount of the accelerator pedal, and the traveling control device controls the switching transistor on / off based on the operation amount of the accelerator pedal to travel. Control the driving speed of the motor. Further, in a forklift using an engine as driving means for driving wheels, the amount of fuel supplied is controlled based on the operation amount of an accelerator pedal, and the number of revolutions of the engine is controlled.

[0003] When a load is carried by a forklift, the load placed on a fork or a pallet vibrates up and down when traveling fast on an uneven road surface. Then, depending on the degree of unevenness or the traveling speed, the load may collapse or the load may fall. In particular, in the case of an unstable load (for example, a large number of stacked papers or a large number of small loads stacked on a pallet), the collapse or drop of the load is likely to occur. Therefore, when traveling on an uneven road surface (bad road), it is necessary to travel at a lower speed than when traveling on a flat road surface. When traveling on an uneven road surface, the driver checks the condition of the load and operates so as not to cause collapse or drop of the load.

[0004]

However, a beginner cannot properly judge the traveling speed with respect to the road surface condition, and if the road changes from a flat road surface to a bad road while traveling with a load, proper deceleration is performed. Failure to do so may result in collapse of the load. Further, when the load is about to collapse, a sudden brake may be applied to apply a large impact to the vehicle body, or the load may move and drop. In addition, even a beginner may run on a bad road without decelerating to an appropriate speed and cause load collapse or load drop. Therefore, the driver drives with great care when traveling on an uneven road surface, so that mental fatigue increases.

[0005] In addition, even if the vibration is of such a degree that the driver does not notice it, depending on the type of load, resonance may occur and load collapse may occur. Further, conventionally, in the case of an unmanned forklift, it is impossible to cope with a change from a flat road surface to a rough road during traveling, so that there is a problem that it can be used only on a flat traveling road surface.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to prevent a forklift from collapsing or falling due to vibration of a load when traveling on an uneven road surface (bad road). An object of the present invention is to provide a travel control device for a forklift capable of suppressing the travel.

[0007]

According to the first aspect of the present invention, there is provided a driving means for driving a driving wheel, a road surface condition detecting means for detecting an uneven state of a running road surface, Road surface condition determining means for determining whether or not the traveling road surface is a rough road based on the detection signal of the road surface condition detecting device; and when the road surface condition determining means outputs a bad road determination signal, the collapse of the load is determined. Control means for controlling the driving means in accordance with a predetermined control condition which can be suppressed.

According to the present invention, in a forklift in which running speed control is performed based on the operation amount of the speed command means, a driving means for driving driving wheels, and an operation for detecting the operation amount of the speed command means. An amount detection unit, a road surface state detection unit that detects an uneven state of the traveling road surface, a road surface state determination unit that determines whether the traveling road surface is a rough road based on a detection signal of the road surface state detection unit, and the operation The driving means is controlled based on the output signals of the amount detecting means and the road surface condition judging means. When the road condition judging means does not output the bad road judging signal, a predetermined signal corresponding to the detection signal of the operation amount detecting means is outputted. The driving means is controlled so that the speed becomes equal to the speed, and when a bad road determination signal is output from the road surface condition determination means, the collapse of the load can be performed regardless of the operation amount of the operation amount detection means. And control means for controlling said drive means in accordance with the braking possible predetermined predetermined control condition.

According to a third aspect of the present invention, in the first or second aspect of the invention, the predetermined control condition is to control the driving means so that the vehicle speed becomes a predetermined low speed. .

According to a fourth aspect of the present invention, in the first aspect of the present invention, the driving means is a motor driven by a battery power supply. In the invention described in claim 5, in the invention described in any one of claims 1 to 4, the road surface condition detecting means is provided at a position where a change in the load of the load loaded on the fork can be detected. Pressure sensor.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the road surface condition determining means determines that the road surface is bad when the output signal of the pressure sensor fluctuates at a predetermined frequency or higher.

Therefore, according to the first aspect of the present invention, the unevenness state of the traveling road surface is detected by the road surface condition detecting means,
Based on the detection signal, the road surface condition determining means determines whether the traveling road surface is a rough road. When the bad road determination signal is output from the road surface condition determination means, the drive means is controlled by the control means in accordance with a predetermined control condition capable of suppressing the collapse of the load.

According to the second aspect of the present invention, when the bad road determination signal is not output from the road surface condition determination means,
The driving means is controlled so as to have a predetermined speed corresponding to the operation amount of the speed command means. When the bad road determination signal is output from the road surface condition determination means, the drive means is controlled by the control means in accordance with a predetermined control condition capable of suppressing the collapse of the load regardless of the operation amount of the operation amount detection means. Controlled.

According to a third aspect of the present invention, in the first or the second aspect of the present invention, the driving means is controlled by the control means such that the vehicle speed becomes a predetermined low speed when traveling on a rough road, and the cargo is loaded. Collapse due to vibration of the vehicle is suppressed.

According to a fourth aspect of the present invention, the driving wheels are driven by a motor driven by a battery power source in the first aspect of the present invention.
According to the invention described in claim 5, in the invention described in any one of claims 1 to 4, a change in the load of the load loaded on the fork is detected by the pressure sensor, and the road surface is detected based on the detection signal. The situation is determined by the road condition determining means.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, when the output signal of the pressure sensor fluctuates at a predetermined frequency or more, the road surface condition determining means determines that the road is bad.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. The battery forklift 1 (hereinafter simply referred to as a forklift) is a four-wheeled vehicle with front-wheel drive and rear-wheel steering. As shown in FIG. 2, an inner mast (not shown) is provided at a front portion of a forklift body 1a between a pair of left and right outer masts 2 so that the fork 3 can be moved up and down via a lift bracket 3a. Is equipped with Then, the fork 3 is moved up and down in accordance with the expansion and contraction operation of the lift cylinder 5. Normally, the fork 3 is placed on the pallet 4
Is carried.

The left and right front wheels 6 as driving wheels are supported by front wheel axles (neither is shown) provided with a differential device. The front axle is a differential gear and a reduction mechanism (not shown)
The driving motor 7 is operatively connected to a driving motor 7 as a driving means via the driving motor 7. The traveling motor 7 is configured to be rotatable in the forward and reverse directions, and the rotation direction thereof can be switched by switching means. Both front wheels 6 are rotated forward and backward according to the forward rotation and reverse rotation of the traveling motor 7.

The forklift 1 is provided with an accelerator pedal 8 as speed command means, and an operation amount (depressed amount) of the accelerator pedal 8 is detected by an accelerator sensor 9 (shown in FIG. 3) as operation amount detecting means. It has become. As the accelerator sensor 9, for example, a potentiometer is used.

On the cylinder bottom of the lift cylinder 5,
A pressure sensor 10 is provided as a road surface condition detecting means for detecting an uneven state of a running road surface. The pressure sensor 10 detects the oil pressure inside the lift cylinder 5 to
A change in the load of the load W loaded on the fork 3 is detected, and a detection signal w corresponding to the internal oil pressure is output. The accelerator sensor 9 and the pressure sensor 10 are electrically connected to the control device 11. The control device 11 is disposed in a housing provided in a counterweight 1b mounted on a rear portion of the vehicle body 1a.

Next, an electrical configuration for controlling the traveling motor 7 will be described with reference to FIG. A series-wound DC motor is used for the traveling motor 7 and is connected to the battery 12. The traveling motor 7 includes an armature 7a and a field winding 7b, and a forward contactor 13 and a reverse contactor 14 are connected to the field winding 7b. Then, the traveling motor 7 is driven to rotate forward and reverse based on the switching operation of both contactors 13 and 14. Flywheel diode 15
a, 15b are the field winding 7b and the contactors 13, 14;
And the battery 12 are connected in parallel. A switching transistor 16 (hereinafter simply referred to as a transistor) as a switching element is connected in series to the traveling motor 7. The transistor 16 is turned on / off based on the chopper signal input to the base terminal, and the current flowing through the traveling motor 7 is controlled to control the rotation speed of the traveling motor 7, that is, the traveling speed of the forklift 1. It is supposed to be.

The control device 11 includes a microcomputer (microcomputer) 17, AD conversion circuits 18 and 19, and a drive circuit 20. The microcomputer 17 includes a CPU (Central Processing Unit) 2 as a road surface condition determination unit and a control unit.
1. ROM (read only memory) 22 as storage means,
A RAM (read / write memory) 23, an input interface 24 and an output interface 25 are provided.

The accelerator sensor 9 is connected to the CPU 21 via the AD conversion circuit 18 and the input interface 24, and the pressure sensor 10 is connected to the CPU 21 via the AD conversion circuit 19 and the input interface 24. The forward switch 26 and the reverse switch 27 are connected to the CPU 21 via the input interface 24. Also,
The CPU 21 includes an output interface 25 and a drive circuit 20.
Is connected to the base terminal of the transistor 16.

The ROM 22 stores various types of control programs including the running control program and data necessary for executing the control programs. ROM22
Stores an equation or a map showing the relationship between the operation amount of the accelerator pedal 8 and the corresponding duty value for chopper control of the transistor 16.

The ROM 22 stores, as data, a reference frequency θ0 as a predetermined frequency for determining whether or not the road surface is a rough road from the output signal of the pressure sensor 10. As the reference frequency θ0, a value obtained experimentally or theoretically is stored. The ROM 22 stores a duty ratio of a chopper signal corresponding to a predetermined low-speed traveling when traveling on a rough road.

The CPU 21 determines based on the detection signal (output signal) w of the pressure sensor 10 whether or not the traveling road surface is a rough road. The CPU 21 calculates the weight of the load placed on the fork 3 based on the detection signal w of the pressure sensor 10, and determines that the road is bad if the value fluctuates at the reference frequency θ0 or more. The CPU 21 controls the traveling motor 7 so as to have a speed corresponding to the operation amount of the accelerator pedal 11 when it is not determined that the road is a bad road. When the CPU 21 determines that the road is rough, the CPU 21 controls the traveling motor 7 in accordance with a predetermined control condition capable of preventing collapse of the load regardless of the operation amount of the accelerator pedal 8. In this embodiment, C
The PU 21 controls the traveling motor 7 so that the vehicle speed becomes a predetermined low speed.

Next, the operation of the traveling control device configured as described above will be described. The CPU 21 determines whether the vehicle is traveling forward or backward based on signals from the forward switch 26 and the reverse switch 27. If the vehicle is traveling forward, the forward contactor 13 is switched to the ON position shown by the chain line in FIG. 3, and the reverse contactor 14 is held at the OFF position shown by the solid line in FIG. When the accelerator pedal 8 is depressed in this state, the transistor 16 is chopper-controlled, and the forklift 1 travels forward.

Hereinafter, the traveling control will be described with reference to the flowchart of FIG. CPU 21 is the accelerator pedal 8
When the vehicle is depressed, the traveling control process shown in FIG. 1 is executed at a predetermined cycle. The CPU 21 sets A in step S1.
The output signal (accelerator signal A) of the accelerator sensor 9 is read via the D conversion circuit 18, and the duty ratio of the chopper signal corresponding to the accelerator signal A is calculated in step S2. Next, the CPU 21 proceeds to step S3, and outputs the chopper signal (drive signal) having the duty ratio calculated in step S2 to the transistor 16 via the output interface 25 and the drive circuit 20. Then, the traveling motor 7 is driven at a speed corresponding to the depression amount of the accelerator pedal 8, and the forklift 1 travels at a speed corresponding to the depression amount of the accelerator pedal 8.

Next, the CPU 21 reads the output signal (load signal w) from the pressure sensor 10 via the AD conversion circuit 19 for a predetermined time in step S4, and stores it in the RAM 23. The predetermined time is set to a time longer than a fluctuation cycle of the load in which the collapse occurs when the fork 3 travels with the load W loaded thereon. In step S5, the CPU 21 calculates the frequency wθ of the load variation from the load signal w read in step S4.
It is determined in step S6 whether the frequency wθ of the load variation is equal to or higher than the reference frequency θ0, that is, whether the road surface is a rough road or not. If the frequency wθ is equal to or higher than the reference frequency θ0, the CPU 21 determines that the road surface is a rough road and
Proceed to.

In step S7, the CPU 21 drives the traveling motor 7 so that the vehicle speed becomes a predetermined low speed.
The chopper signal having the duty ratio stored in the OM 22 is output to the transistor 16 via the output interface 25 and the drive circuit 20. As a result, the traveling motor 7
Is driven at a predetermined low speed capable of suppressing the collapse of the load regardless of the depression amount of the accelerator pedal 8. That is, on a rough road, the forklift 1 travels at a preset low speed even if the accelerator pedal 8 is depressed by a large amount.

In step S6, the frequency wθ is equal to the reference frequency θ.
If it is less than 0, the CPU 21 determines that the road surface is not a bad road, and proceeds to step S8. In step S8, step S2
The chopper signal having the duty ratio calculated by the above is output to the transistor 16 via the output interface 25 and the drive circuit 20.
Output to Therefore, the forklift 1 travels at a speed corresponding to the depression amount of the accelerator pedal 8.

Then, the CPU 21 executes the running control process at a predetermined cycle until the depression of the accelerator pedal 8 is released. This embodiment has the following effects.

(1) Road surface condition determining means (CPU 21)
When a bad road determination signal is output from the vehicle, the traveling motor 7 is driven by the control means (CPU 21) in accordance with a predetermined control condition capable of suppressing the collapse of the load regardless of the depression amount of the accelerator pedal 8. Is done. Therefore, even if the driver does not perform appropriate speed control corresponding to rough roads, the collapse of the load is suppressed, the load is prevented from falling, and even a novice can work safely and mental fatigue. Is reduced.

(2) Since the predetermined control condition is to control the traveling motor 7 so that the vehicle speed becomes a predetermined low speed, the control is facilitated. (3) Since the forklift 1 is configured to drive the front wheels 6 (drive wheels) by the traveling motor 7 using the battery 12 as a power source, the depression amount of the accelerator pedal 8 is smaller than that of the forklift using the engine as a drive source. This makes it easy to control the front wheels 6 to drive at a predetermined low speed irrespective of the speed.

(4) Since the road surface condition detecting means is constituted by the pressure sensor 10 provided at a position where the load change of the load W loaded on the fork 3 can be detected, the condition of the traveling road surface may cause the collapse of the load. It is possible to obtain appropriate data for determining whether or not the road is easy to perform.

(5) CPU 21 (road surface condition determining means)
When the output signal (detection signal) of the pressure sensor 10 fluctuates in advance at a predetermined frequency or more at which the collapse of the load is likely to occur, it is determined that the road is a bad road. Can be.

(6) The road surface condition determining means is constituted by the microcomputer 17, and the ROM 22 (storage means)
Is determined based on the data indicating the relationship between the fluctuation period and the road surface condition stored in the pressure sensor and the output signal of the pressure sensor 10. Therefore, the accuracy of determining whether or not the vehicle is on a rough road is improved, and by changing the data stored in the storage means by using common hardware, the present invention can be easily performed even for forklifts of different models.

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. This embodiment is different from the above-described embodiment in that the criterion for determining whether the road is a rough road is changed in accordance with the load of the load W loaded on the fork 3. The hardware configurations of the forklift 1 and the control device 11 are the same as those of the above-described embodiment, and a part of the control program and predetermined frequency data stored in the ROM 22 for determining whether the road is a bad road or not. Are different. The predetermined frequency data for determining whether the road surface is rough or not depends on the magnitude of the load,
Reference numeral 2 stores the value of the reference frequency θi experimentally or theoretically obtained by changing the load of the load W in correspondence with a plurality of loading loads. Further, in this embodiment, a predetermined low speed for suppressing the collapse of the load when traveling on a rough road is set in accordance with the load of the load W.
Stores the duty ratio of the chopper signal corresponding to the predetermined low speed, corresponding to the load WG. The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description is omitted.

The CPU 21 inputs the output signal of the pressure sensor 10 as soon as the accelerator pedal 8 is depressed, that is, as soon as the operation amount of the accelerator sensor 9 changes from 0, and calculates the load of the load W from the value. And its value WG
Is stored in the RAM 23. This value WG is updated each time the operation amount of the accelerator sensor 9 changes from 0,
It is stored in the RAM 23.

Next, according to the flowchart of FIG.
The traveling control of No. 21 will be described. While the accelerator pedal 8 is depressed, the CPU 21 executes the traveling control process shown in FIG. 4 at a predetermined cycle. The CPU 21 determines in step S11 that the accelerator sensor 9 has been
The output signal (accelerator signal A) is read, and step S
At 12, the duty ratio of the chopper signal corresponding to the accelerator signal A is calculated. Next, the CPU 21 proceeds to step S13, and outputs the chopper signal having the duty ratio calculated in step S12 to the transistor 16 via the output interface 25 and the drive circuit 20. Then, the traveling motor 7 is driven at a speed corresponding to the depression amount of the accelerator pedal 8, and the forklift 1 travels at a speed corresponding to the depression amount of the accelerator pedal 8.

Next, the CPU 21 reads the output signal (load signal w) from the pressure sensor 10 via the AD conversion circuit 19 for a predetermined time in step S14, and stores it in the RAM 23. The predetermined time is set to a time longer than a fluctuation cycle of the load in which the collapse occurs when the fork 3 travels with the load W loaded thereon. The CPU 21 calculates the load fluctuation frequency wθ from the load signal w read in step S14 in step S15, and calculates a predetermined frequency θi corresponding to the load WG of the load in step S16. Then, the CPU 21 determines in step S17 that the frequency wθ of the load change is equal to the predetermined frequency θ.
It is determined whether or not the road surface is i or more, that is, whether or not the road surface is a rough road. If the frequency wθ is equal to or higher than the predetermined frequency θi, the CPU 21 determines that the road surface is a bad road, and proceeds to step S18.

In step S18, the CPU 21 determines that the vehicle speed is the load W.
And a chopper signal having a duty ratio for driving the traveling motor 7 so that the speed becomes a predetermined low speed corresponding to the load WG, and outputs the chopper signal to the output interface 25.
And the output to the transistor 16 via the drive circuit 20. As a result, the traveling motor 7 is driven at a predetermined low speed capable of suppressing the collapse of the load regardless of the depression amount of the accelerator pedal 8. That is, in the case of a bad road, the forklift 1 travels at a preset low speed corresponding to the load WG of the load W, even if the depression amount of the accelerator pedal 8 is large.

If the frequency wθ is less than the predetermined frequency θi in step S17, the CPU 21 determines that the road surface is not a rough road, and proceeds to step S19. In step S19, the chopper signal having the duty ratio calculated in step S12 is output to the transistor 16 via the output interface 25 and the drive circuit 20. Therefore, the forklift 1 travels at a speed corresponding to the depression amount of the accelerator pedal 8.

Then, the CPU 21 executes the running control process at a predetermined cycle until the depression of the accelerator pedal 8 is released. Forklift 1 from the road surface through the tire
When the frequency of the vibration applied to the forklift 1 coincides with the natural frequency of the entire forklift 1 including the load W, the vibration of the forklift 1 increases and the collapse of the load easily occurs. The natural frequency of the vehicle body 1a of the forklift 1
If the mass of a is M and the spring constant of the suspension is k, it is proportional to √ (k / M). That is, forklift 1
Is affected by the magnitude of the load WG of the load W, and if the frequency θi serving as a criterion for determining whether the road is a rough road is changed by the load WG, a more appropriate determination can be made.

Therefore, this embodiment has the following effects in addition to the effects (1) to (6) of the above embodiment. (7) Since the criterion for determining whether the road is a rough road is changed in accordance with the load of the load W, the determination of whether the road is a rough road is more appropriate. Accordingly, the traveling speed is not unnecessarily changed to a low speed at a frequency at which the collapse of the load is less likely to occur, so that it is possible to suppress a decrease in the efficiency of the load transport operation.

(8) The load WG of the load W is calculated when the operation amount of the accelerator sensor 9 changes from 0, that is, based on the output signal of the pressure sensor 10 immediately after traveling. Can be accurately obtained with little influence of vibration or the like.

The embodiment is not limited to the above, and may be embodied as follows, for example. When determining whether or not the road is rough, based on the load variation, the determination may be made in consideration of not only the frequency of the vibration but also the amplitude. Even if the frequency is equal to or higher than the reference frequencies θ0 and θi, the load may not collapse if the amplitude is small. Therefore, by taking the amplitude into consideration, the determination as to whether the road is rough or not becomes more accurate, and the chance of performing unnecessary deceleration of the traveling speed in a state in which the load is unlikely to collapse is reduced, thereby improving work efficiency.

When it is determined whether or not the road is rough, based on the load variation, the type of load may be considered in addition to the frequency and amplitude of the vibration. For example, the reference frequencies θ0 and θi are set according to whether a plurality of loads W are placed on the pallet 4, one load is placed, or a large number of sheets are stacked. May be set separately. In this case, the input device for selecting or inputting the type of the load requires an operation of inputting the control device by the driver in advance. However, the determination of the rough road is more accurate, and the work efficiency is further improved. .

When the road surface condition judging means judges that the road is rough, that is, when the road condition judging device outputs a bad road judgment signal, the speed is reduced to a predetermined low speed as a control condition for suppressing the collapse of the load. Instead, control for prohibiting acceleration may be performed. When traveling on a rough road, it is normal for the operator to travel in a decelerating state than when traveling on a non-rough road surface, and the operator performs acceleration operation when he does not recognize that it is a rough road Most of the errors are caused by erroneous operations. When the worker does not recognize the road as a bad road, the load W is less shifted, and the load does not collapse immediately without deceleration. In addition, the road surface of the rough road may be short, and even if prohibiting acceleration, there is an effect of suppressing collapse of the load.

The driving means for driving the driving wheels is not limited to a motor, but may be a gasoline engine, a diesel engine, an LP, or the like.
An engine such as a gas engine or a natural gas engine may be used. In this case, it is necessary to use an engine whose fuel injection amount, intake amount, and the like are electronically controlled. The traveling control device controls the amount of fuel injected by the engine, the amount of intake air, and the like in accordance with the operation amount of the speed command means when traveling on a road surface that is not a rough road. Instead, the fuel injection amount, the intake air amount, and the like are controlled so that the vehicle speed becomes a predetermined low speed or acceleration is not performed according to a predetermined control condition.

The mounting position of the pressure sensor 10 is not limited to the bottom of the lift cylinder 5 but may be any position at which the hydraulic pressure of the lift cylinder 5 corresponding to the load acting on the fork can be measured. It may be provided in the middle.

Instead of a sensor capable of detecting a change in the load of a load by measuring the oil pressure, a sensor that directly or indirectly detects the pressure of the load loaded on the fork 3 may be used. For example, load cell with fork 3
Or on a lift bracket 3a that receives a force acting on the fork 3.

A sensor for detecting unevenness of the road surface, for example, an image sensor, is used as the road surface condition detecting means, and the road surface unevenness state is determined by the road surface condition determining means based on the signal. It may be configured to judge whether or not. However, in this case, the processing of the detection signal from the road surface condition detecting means and the processing of determining whether or not the road is rough are more complicated than those performed based on the load change.

○ Data used for determining whether or not the road is bad,
EEPROM (electrically erasable ROM) as storage means instead of storing maps or functions in ROM 22
Alternatively, the information may be stored in a RAM provided with a backup battery.

The present invention is not limited to a forklift operated by a driver, and may be applied to an unmanned forklift whose traveling is controlled in advance according to a predetermined speed pattern. Conventional unmanned forklift trucks are not equipped with a means for preventing the occurrence of load collapse due to vibration, and therefore require a road surface with little unevenness as a traveling path. However, by applying the traveling control device of each of the above embodiments, maintenance of the traveling path is simplified.

The accelerator pedal 8 is used as speed command means.
Alternatively, a manual lever may be provided, and the speed command may be issued according to the operation amount of the lever. The AC motor may be used as the traveling motor 7 instead of the DC motor.

As the switching means for changing the rotation direction of the traveling motor 7, a transistor may be used as a non-contact switch instead of the forward contactor 13 and the reverse contactor 14.

The transistor 16 only needs to have a switching function, and a transistor other than a bipolar transistor may be used. Further, a switching element such as a thyristor may be used instead of the transistor.

The drive wheels may be rear wheels or may be applied to forklifts of three-wheeled vehicles. Regarding technical ideas (inventions) other than those described in the claims that can be understood from each of the embodiments,
The effect is described below.

(1) In the invention described in claim 5,
The pressure sensor is provided at a position where the bottom pressure of the lift cylinder can be detected. In this case, it is easy to secure a space for mounting the pressure sensor, and it is possible to accurately detect a change in the load of the load.

(2) In the invention described in claim 1 or 2, the predetermined control condition is to prohibit acceleration. In this case, even if acceleration is performed according to a preset control program or a command from the speed command means, acceleration is not performed on a rough road surface, and load collapse is suppressed to prevent load drop. Is done.

(3) In the invention according to claim 6,
The road surface condition determination means is constituted by a microcomputer, and the storage means stores the relationship between the load fluctuation amount or fluctuation period and the road surface condition as a map or function corresponding to a plurality of loads, and the microcomputer stores the map or function. Is determined on the basis of the road. In this case, the accuracy of the determination as to whether or not the vehicle is on a rough road is improved, and the common hardware can be used to change the map or the function stored in the storage means, so that it can be easily performed in vehicles of different models. .

(4) In the first aspect, the forklift is an unmanned forklift. in this case,
Unlike a conventional unmanned forklift, it is possible to convey a load on a rough road surface while suppressing collapse of the load and falling of the load on a rough road, similarly to the manned forklift.

(5) Based on the detection signal of the road surface condition detecting means for detecting the unevenness of the running road surface, the road surface condition determining means determines whether or not the running road surface is a bad road. A traveling control method for a forklift, wherein when it is determined, the control unit controls the driving unit of the driving wheel according to a predetermined control condition capable of preventing collapse of the load. In this case, when the forklift travels on an uneven road surface (bad road), it is possible to suppress the collapse of the load due to the vibration of the load and prevent the load from falling.

The term “bad road” as used herein means an uneven road surface where the collapse of the forklift easily occurs when the forklift continues to run at the current running speed. Therefore, even on a road surface having the same unevenness, there are cases where the road is determined to be “bad road” and cases where it is not determined to be “bad road” depending on the traveling speed, the type of load, the magnitude of load, and the like.

[0066]

As described in detail above, claims 1 to 6 are provided.
According to the invention described in (1), when the forklift travels on an uneven road surface (bad road), it is possible to suppress collapse of the load and drop of the load due to vibration of the load.

According to the second aspect of the invention, in a forklift in which the traveling speed is controlled based on the operation amount of the speed command means, when the vehicle travels on a rough road, the cargo collapses due to the vibration of the cargo or the load falls. Can be suppressed.

According to the third aspect of the invention, control when traveling on a rough road becomes easy. According to the invention described in claim 4, the control is simpler than that of a forklift using an engine.

According to the fifth aspect of the present invention, it is easier to determine whether or not a road is rough, as compared with the case where the road surface condition is determined based on an image. According to the invention described in claim 6, it is easy and accurate to determine whether or not the road is rough.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a traveling control processing procedure according to a first embodiment.

FIG. 2 is a side view of a forklift.

FIG. 3 is a block diagram showing an electrical configuration of a travel control device.

FIG. 4 is a flowchart illustrating a traveling control processing procedure according to the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift, 3 ... Fork, 6 ... Front wheel as drive wheel, 7 ... Running motor as drive means, 8 ... Accelerator pedal as speed command means, 9 ... Accelerator sensor as operation amount detection means, 10 ... Road surface A pressure sensor as a situation detecting means; 12 a battery; 21 a CPU as a road surface condition judging means and a control means;

Claims (6)

[Claims] A driving means for driving driving wheels; a road surface condition detecting means for detecting an uneven state of the road surface; and a determination as to whether the road surface is a rough road based on a detection signal of the road surface condition detecting means. A road surface condition determining means for performing, and when a bad road determination signal is output from the road surface condition determining means, a control means for controlling the driving means in accordance with a predetermined control condition capable of suppressing collapse of a load. Traveling control device for a forklift equipped with a. 2. A forklift in which traveling speed control is performed based on an operation amount of a speed commanding means, a driving means for driving a driving wheel, an operation amount detecting means for detecting an operation amount of the speed commanding means, and a traveling road surface. Road surface condition detecting means for detecting the unevenness state of the road surface condition; road surface condition determining means for determining whether or not the traveling road surface is a rough road based on the detection signal of the road surface condition detecting device; the operation amount detecting means and the road surface condition The driving means is controlled based on the output signal of the judging means, and when the road condition judging means does not output the bad road judging signal, the driving speed becomes a predetermined speed corresponding to the detection signal of the operation amount detecting means. A predetermined value capable of controlling the driving means and suppressing collapse of the load regardless of the operation amount of the operation amount detecting means when the bad road judgment signal is output from the road surface condition judging means. Running control device for a forklift comprising a control means for controlling said drive means in accordance with a predetermined control condition. 3. The forklift traveling control device according to claim 1, wherein the predetermined control condition is to control the driving means so that a vehicle speed becomes a predetermined low speed. 4. The travel control device for a forklift according to claim 1, wherein the drive unit is a motor driven by a battery power supply. 5. The forklift according to claim 1, wherein said road surface condition detecting means is a pressure sensor provided at a position capable of detecting a change in load of a load loaded on the fork. Travel control device. 6. The forklift traveling control device according to claim 5, wherein the road surface condition determining means determines that the road surface is bad when the output signal of the pressure sensor fluctuates at a predetermined frequency or higher.