JPH09110392A - Industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a body turn surely without entailing any nonconformity such as the wear of a tire and a drop in operation efficiency and so on at an accelerating change in starting and braking or the like in time of skewing and crosswise moving forward. SOLUTION: A load wheel 4 or a front side steering wheel is driven by a motor 17 only at the time of starting in a state of being steered in the crosswise forward direction (steering angle 90 deg.) as well as it is braked by a braking device 29 only at the time of in the said state, respectively. A microprocessing unit 32 computes the driving force of a load wheel 4, where a car body is not turned, on the basis of center-round moment made by travel resistance of another load wheel 5 or a caster wheel and driving force of a drive wheel 5, and the motor 17 is voltage-controlled so as to make the fricing force securable. The travel resistance and a center position are operated by a detected value out of two load cells 21 and 22 detecting each wheel load of these load wheels 4 and 5. In addition, two braking devices 29 and 30 are synchronously operated, and thereby each braking force is set to the specified ratio making the car body unrotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial vehicle in which two front wheels are steered wheels and caster wheels, and at least one rear wheel is a driving wheel that also serves as a steered wheel, and particularly when starting or braking during lateral movement. The present invention relates to an industrial vehicle that maintains its posture when the acceleration changes, such as time.

[0002]

2. Description of the Related Art In a four-way forklift, for example, one rear wheel, which is a drive wheel that also serves as a steered wheel, is provided on the left or right side, and at the same time, the front wheel located on the rear wheel side is a caster wheel. The front wheels located on the opposite side are steered wheels, and by adjusting the steering angles of the front and rear steered wheels to a predetermined angle, the driving force of the rear wheels does not change the vehicle body posture but moves forward and backward as well as laterally (laterally). ), It can also move diagonally. For example, when it is not possible to turn a long object due to the passage width, it moves laterally to carry a load. A caster wheel, which is usually an auxiliary wheel, is provided near the opposite side of the rear wheel.

That is, as shown in FIG. 9, in a 4-way forklift 51 (hereinafter referred to as a forklift), a road wheel 52 on the right side of the front wheel can be steered in a 90 ° range by operating a lever (not shown), and is provided on the left side of the vehicle body. The drive wheel 54 which is the rear wheel is steerable within a 360 ° range by operating a steering wheel (not shown). Further, the road wheel 53 on the left side and the caster wheels 55 provided on the right side of the vehicle body can freely rotate. The forklift 51 travels when the drive wheel 54 is driven by a travel motor (not shown).

When the drive wheel 54 is driven, a running resistance opposite to the driving force of the drive wheel 54 acts on the road wheels 52 and 53. Therefore, a moment acts around the center of gravity G due to the driving force F and the running resistances f1 and f2 at the time of starting the vehicle.

As shown in FIG. 9, when traveling to the right (downward in the figure), the driving force F generated in the drive wheel 54 causes the moment F · L of the force in the counterclockwise direction about the center of gravity G as a center. work. Also, due to the running resistances f1 and f2 on the road wheels 52 and 53, the counterclockwise force moments f1 · d1, f2 · d2 centering on the center of gravity G are also generated.
Each work. Therefore, both moments act counterclockwise around the center of gravity G, so that the vehicle body turns when starting.

Particularly, when the load is loaded, the running resistances f1 and f2
In addition, the driving force F needs to be increased, which makes it easier to turn. Also, during mastreach,
Since the running resistances f1 and f2 increase and the distance L increases, it becomes easy to turn even if the decrease in the distances d1 and d2 is subtracted.

In the forklift 51, the brake is attached only to the drive wheel 54 which is the drive wheel. When the vehicle is braked while moving to the left and right, a relatively large turning moment M (= mβL; where m is the total vehicle weight and β is deceleration) is relatively large on the drive wheel 54 due to the braking force of the drive wheel 54. Since the wheels are in a state where the Ackerman can be steered around, the turning of the vehicle body occurs even during braking.

Conventionally, in order to prevent the vehicle body from turning during acceleration changes such as starting or braking during left-right traveling,
In the actual work, it was dealt with as follows. (1) When starting ... Drive wheel 5 as shown in FIG.
The vehicle body 4 is prevented from turning by intentionally cutting 4 at an angle (cutting angle θ) with respect to the traveling direction and suppressing the turning moment at the time of starting. Alternatively, it was left to take turns to start the vehicle and immediately correct the course.

(2) During braking: It is more difficult to correct the posture by steering when turning the vehicle body than when starting. Therefore, in actual work, slow braking is usually applied so that the deceleration is small, and sudden braking is not applied. Was doing.

[0010]

However, if the steering wheel is slightly cut with respect to the traveling direction at the time of starting, the drive wheel 54 is slid obliquely with respect to the traveling direction, and the tire is worn greatly, and Since the loss of the driving force is large, the acceleration is dull and the loss is large in terms of time, and in the case of a battery vehicle, the operating time of the battery is reduced.

In addition, considering that the long body is often handled due to the nature of this model, when the course is corrected after starting the vehicle, the unnecessary turning (runout) of the vehicle body is swung unnecessarily. It was a problem in use because it would happen. Also,
During braking, the braking was applied slowly to reduce the deceleration, so the braking was applied early and the work efficiency was unavoidably reduced.

In a reach type forklift (multi-forklift) disclosed in Japanese Patent Laid-Open No. 5-116643, in which both front wheels are steered wheels and two front wheels and a driving wheel can be steered in parallel in a parallel movement mode, one of the front wheels is a caster. The resistance of the tire to the turning moment is greater than that of a 4-way forklift, which is a wheel. Therefore, it is considered that the turning of the vehicle body when starting in the left-right direction is alleviated. Further, since the driving wheels do not skid sideways, the wear of the tire can be reduced.

Further, in the reach type forklift (multi-forklift) disclosed in Japanese Unexamined Patent Publication No. 5-246347, one of the road wheels has three wheels so that the Ackermann steering around the drive wheels cannot be performed simultaneously with braking. Steering is performed so that the axes of the vehicle do not intersect at one point, thereby suppressing changes in vehicle body posture (turning). Therefore, sudden braking is relatively possible.

However, even in these multi-forklifts, the running resistance of the road wheel at the time of starting is only increased to relatively reduce the moment for turning the vehicle body. Does not reach.

Further, steering the road wheel so that the Ackermann cannot be steered during braking causes the road wheel to slide laterally (or diagonally) with respect to the traveling direction to apply braking. Wear is brought about.

In addition, in the multi-forklift, it is necessary to equip the left and right road wheel parts with independent steering devices and a control device for controlling them according to the steering of the driving wheels.
The forklift itself has to be very expensive. Therefore, the present situation is that there has not been provided a means for reliably solving the vehicle body turning at the time of acceleration change such as starting or braking during lateral movement at low cost and without causing tire wear due to sideslip. .

The present invention has been made to solve the above problems, and its purpose is to reduce tire wear and work efficiency due to skidding during acceleration changes such as starting and braking during oblique traveling and lateral traveling. An object of the present invention is to provide an industrial vehicle capable of reliably suppressing turning of the vehicle body without causing a problem such as deterioration of the vehicle.

[0018]

In order to solve the above problems, according to the invention of claim 1, at least one of the front two wheels is a steerable front wheel, and at least a steered wheel which also serves as a drive wheel is provided on the rear side. In an industrial vehicle having one wheel, drive means for driving the front steered wheel is provided.

According to the second aspect of the invention, the drive means prevents the vehicle body from turning by the driving force of the front steered wheels even by a moment acting around the center of gravity of the vehicle based on the driving force of the driving wheels. The driving force setting means for setting is provided.

According to the third aspect of the present invention, in the driving force setting means, the moment around the center of gravity of the vehicle based on the driving force of the front steered wheels is applied to the running resistance acting on the driven front wheels other than the front steered wheels. The driving force of the front steered wheels is set so as to be equal to the sum of the moment around the center of gravity of the vehicle based on the driving force and the moment around the center of gravity of the vehicle based on the driving force of the driving wheels.

According to a fourth aspect of the present invention, there is provided rudder angle detecting means capable of detecting the rudder angle of the front steered wheel, and the drive means is configured such that the steered angle of the front steered wheel is predetermined by the rudder angle detecting means. The front steered wheels are driven only when it is detected that the steering wheel is in the angular range.

According to a fifth aspect of the present invention, the vehicle speed detecting means is provided, and the driving means stops the driving of the front steered wheels when the vehicle speed after starting reaches a predetermined speed. In the invention according to claim 6, the parameter of the running resistance of the driven front wheels required for the driving force setting means to set the driving force of the front steered wheels can be changed according to the road surface condition. Equipped with means.

According to a seventh aspect of the present invention, in one of the front wheels, one of the two front wheels is a front steered wheel, and in the industrial vehicle equipped with a rear steerable drive wheel, the front steered wheel is at least during braking of the drive wheel. And a braking means for braking.

In the invention according to claim 8, the vehicle body does not turn due to the braking force of the front steered wheels braked by the braking means due to the moment acting around the center of gravity of the vehicle based on the braking force of the drive wheels. Was set as.

According to a ninth aspect of the present invention, there is provided rudder angle detecting means capable of detecting the rudder angle of the front steered wheel, and the braking means has the rudder angle of the front steered wheel determined by the rudder angle detecting means. The front steered wheels are braked only when it is detected that they are within the angular range.

According to a tenth aspect of the present invention, an industrial vehicle is the driving means according to any one of the first to sixth aspects and the seventh aspect to the ninth aspect. And braking means.

According to the first and tenth aspects of the present invention, for example, when the vehicle is diagonally moving or moving left and right, the moment around the center of gravity based on the driving force of the driving wheels, which are the rear wheels, is relatively large. The car body easily turns and starts. However, when the front steered wheels are driven by the driving means, the respective moments for turning the vehicle body are suppressed or canceled, and the vehicle body does not turn but smoothly starts in the steering direction.

According to the second and tenth aspects of the present invention, the driving force setting means causes the front steered wheels to rotate the vehicle body such as a moment caused by the driving force of the driving wheels, that is, the vehicle body does not turn. It is driven by a driving force that can generate a moment sufficient to cancel the desired moment. As a result, it becomes possible to reliably and smoothly start the vehicle body in the steering direction even when traveling diagonally or traveling left and right.

According to the third and tenth aspects of the present invention, the driving force of the front steered wheels is changed by the driving force setting means.
The moment around the center of gravity of the vehicle based on the driving force is the sum of the moment around the center of gravity of the vehicle based on the running resistance of the driven front wheels other than the front steered wheels and the moment around the center of gravity of the vehicle based on the driving force of the driving wheels. Set to be equal.

According to the fourth and tenth aspects of the present invention, the steering angle of the front steered wheels is detected by the steering angle detecting means, and the steering angle is within a predetermined angle range in which the vehicle body is relatively easy to turn. Only the drive means drives the front steered wheels.
That is, the front steered wheels are driven only when it is necessary to prevent the vehicle body from turning at the time of starting when the vehicle is moving diagonally or left and right.

According to the fifth and tenth aspects of the present invention, when the vehicle speed detected by the vehicle speed detecting means reaches a predetermined speed after starting, the driving of the front steered wheels by the driving means is stopped. As a result, the front steered wheels are driven only when the vehicle is prone to start turning.

According to the sixth and tenth aspects of the invention, the parameter of the running resistance of the driven front wheels, which is necessary for the driving force setting means to set the driving force of the front steered wheels, is as follows:
It is changed by the parameter changing means according to the road surface condition. As a result, the driving force of the front steered wheels is set to an appropriate value according to the road surface condition.

According to the seventh and tenth aspects of the present invention, when the driving wheel which is the rear wheel is braked at the time of diagonally advancing or moving left and right, the braking force of the driving wheel causes the vehicle to rotate around the center of gravity of the vehicle. Due to the acting moment, the vehicle body can easily turn. However, when the drive wheels are braked, the front steered wheels are braked by the braking means, so that the moment that tries to turn the vehicle body is suppressed or canceled, and the vehicle body does not turn but smoothly brakes while maintaining its steering posture. To be done.

According to the eighth and tenth aspects of the present invention, the braking force of the front steered wheels that is braked by the braking means causes the vehicle body to move by the moment acting around the center of gravity of the vehicle based on the braking force of the driving wheels. It is set not to turn.
That is, the front steered wheels are braked by a braking force that can generate a moment sufficient to cancel the moment of turning the vehicle body by braking the drive wheels. Therefore, turning of the vehicle body during braking can be reliably suppressed.

According to the ninth and tenth aspects of the present invention, the steering angle of the front steered wheels is detected by the steering angle detecting means, and the steering angle is within a predetermined angle range in which the vehicle body is relatively easy to turn. The front steering wheel is braked only by the braking means.
That is, the front steered wheels are braked only when it is necessary to prevent the vehicle body from turning during braking, such as when the vehicle is diagonally moving or when moving left and right.

According to the invention described in claim 10, the drive means according to any one of claims 1 to 6 and the braking means according to any one of claims 7 to 9 are provided. As a result, the vehicle is started and braked smoothly without turning the vehicle body.

[0037]

DETAILED DESCRIPTION OF THE INVENTION A 4-way forklift embodying the present invention will be described below with reference to FIGS.

As shown in FIG. 2, a 4-way forklift 1 as an industrial vehicle has a machine base 1a with a fork 2 interposed therebetween.
A pair of legs 3 (shown in FIG. 4) extending forward from the vehicle are provided with road wheels 4 as steering wheels and load wheels 5 made of caster wheels as driven front wheels, respectively, and drive wheels are provided at the rear of the machine base. Drive wheels 6 and caster wheels 7 are provided.

The drive wheel 6 is rotated by turning a steering wheel 9 provided in a driver's cab 8
The road wheel 4 is steered in a range of 60 °, and the road wheel 4 is steered in a range of 90 ° by operating the handle lever 11 provided on the instrument panel 10 back and forth.

The drive wheel 6 is a steering motor (not shown) according to the turning amount of the steering wheel 9.
Steered by. In addition, the drive wheel 6 is an accelerator lever 1 provided on the instrument panel 10.
It is driven by the traveling motor 13 (shown in FIG. 1) with a driving force corresponding to the operation amount of 2.

The road wheel 4 is rotatably supported in a housing 14 which is pivotally attached to a frame 1b extending from the machine base 1a. Housing 1
The rod 15a of the cylinder 15 is connected to the outer peripheral end of the cylinder 4, and the operation of the cylinder 15 that is expanded and contracted by hydraulic control based on the operation of the handle lever 11 causes the steering angle to be changed according to the stop position of the handle lever 11. The road wheel 4 is steered.

As shown in FIG. 3, a motor 17 which constitutes a driving means having a clutch mechanism 16 (shown in FIG. 1) is arranged in the housing 14, and the driving force of the motor 17 is for deceleration. It is adapted to be transmitted to the road wheel 4 via the gear train 18.

A limit switch 19 (shown in FIG. 1) as a steering angle detecting means is arranged near the outer periphery of the housing 14 with its detecting portion in contact with the housing 14, and the road wheel 4 moves left and right. The steering angle at time is almost 9
When it is arranged at 0 °, the limit switch 19 is turned on.

Further, as shown in FIG. 2, the road wheel 5
Is rotatably supported in a housing 20 that is pivotally attached to the left frame 1b. The left and right road wheels 4 and 5 are attached to the attachment portions of the housings 14 and 20 to the frame 1b. Load cells 21 and 22 (shown in FIG. 1) for detecting the applied wheel load are respectively interposed.

Instrument panel 10 in cab 8
In accordance with the operation of the cargo handling lever 23 provided above, the mast 2
4 is adapted to slide in the vertical direction by the expansion / contraction drive of a hydraulic cylinder 25 (shown in FIG. 1).
The fork 2 is moved up and down by sliding. The mast 24 can be moved back and forth (reach) with respect to the machine base 1a by driving a hydraulic cylinder (not shown) in response to the operation of the cargo handling lever 23.
The fork 2 is operated back and forth by moving the fork 4 back and forth. The hydraulic cylinder 25 is provided with a pressure sensor 26 (shown in FIG. 1), and the pressure sensor 26 detects the load weight of the load on the fork 2.

A brake pedal 27 is provided on the floor surface of the cab 8, and the amount of depression of the brake pedal 27 is detected by a brake switch 28 (shown in FIG. 1). In addition, the road wheel 4 is provided with a brake device 29 which constitutes a braking means,
Brake devices 30 (both of which are shown in FIG. 1) are attached to each of them, and each is a deadman type brake in which braking is released by depressing the brake pedal 27. The brake device 29 is adapted to be braked only at a later-described predetermined time (when traveling in the horizontal direction). Further, the 4-way forklift 1 is provided with a controller 31 which controls traveling drive control, cargo handling drive control, and the like.

FIG. 1 is a block diagram showing the electrical construction of a vehicle body posture holding device mounted on the 4-way forklift 1. The controller 31 constitutes a driving unit and a braking unit and also serves as a driving force setting unit.
2, an A / D converter 33, and a motor drive circuit 34 that constitutes a drive means. A memory 35 is provided in the MPU 32.

The MPU 32 has a potentiometer 36 for detecting the operation amount of the accelerator lever 12, a limit switch 19, a brake switch 28, and brake devices 29, 3.
0, the clutch mechanism 16 and the rotation sensor 37 as a vehicle speed detecting means for detecting the vehicle speed are connected. The pressure sensor 26 and the load cells 21 and 22 are connected to the MPU 32 via the A / D converter 33, and the motors 13 and 17 are connected to the MPU 32 via the motor drive circuit 34.
It is connected to PU32.

Based on the detection signal from the potentiometer 36, the MPU 32 controls the drive of the traveling motor 13 via the motor drive circuit 34 so that the drive force is set according to the operation amount of the accelerator lever 12, that is, the accelerator opening degree.

The motor 17 is driven only when the limit switch 19 is turned on, and the limit switch 1
Only when 9 is turned on, the clutch mechanism 16 is operated in the connected state. That is, when the limit switch 19 is off, the clutch mechanism 16 is in the separated state, and the motor 17 is not driven even if the accelerator signal is input from the potentiometer 36. Memory 3
5 stores program data for calculating the drive voltage of the motor 17, and the drive voltage is stored in the load cells 21, 22, the pressure sensor 26 and the potentiometer 3.
It is calculated by the MPU 32 based on the program data using various input data based on the detection signal from 6.

The arithmetic expressions and map data stored in the memory 35 for use in the processing on the program data will be described below. The memory 35 stores map data M1 indicating the relationship between the accelerator opening A obtained based on the detection signal from the potentiometer 36 and the driving force F of the drive wheel 6. Further, the memory 35 stores the following arithmetic expression for calculating the running resistance f2 of the road wheel 4 from the wheel load N1 of the road wheel 4.

F2 = F (N1) (1) This equation (1) is an empirical formula obtained by test traveling, and the traveling resistance f2 is expressed as a function of the wheel load N1. The coefficient of friction μ with the road surface used in this test formula is set to an average value μ o (for example, assuming an asphalt road surface).

Map data M2 showing the relationship between the detection signal from the pressure sensor 26 and the loaded weight w of the load on the fork 2.
Is stored in the memory 35, and the map data M2
Is used to calculate the loaded weight w from the detection signal of the pressure sensor 26. The loaded weight w is used to calculate the position of the center of gravity G of the vehicle in the machine front-rear direction, that is, the distances L, d1, and d2. In addition, as shown in FIG.
Is the vertical distance from the center of turning of the drive wheel 6 to the center of gravity, and the distances d1 and d are the vertical distances from the road wheels 4 and 5 to the center of gravity, respectively. These distances L, d1, d
The calculation of 2 is stored in the memory 35 and can be obtained by the following procedure.

That is, the position of the center of gravity of the weight W with only a known machine stand (empty load) and the position of the center of gravity such that the wheel weights N1 and N2 of the detected load wheels 4 and 5 are also obtained. From the above, the center of gravity position at the machine stand weight W + the loaded weight w is obtained.

The position of the center of gravity of only the known machine frame changes depending on the reach state of the mast 24, but the reach state of the mast 24 and the change of the front and rear wheel weights have the relationship shown in FIG. Since it is known that the position of the center of gravity can be easily obtained. In this graph, the position of the mast is shown by the distance from the origin when the position of the mast 24 when retracted is the origin (see FIG. 7).

In the memory 35, the driving force D of the road wheel 4 is calculated using the running resistance f2 and the distance L obtained by the MPU 32 and the driving force F of the drive wheel 6 obtained from the accelerator opening A. The following calculation formulas for are stored.

D = (F · L + f2 · d2) / d1 (2) As can be seen from FIG. 4, the counterclockwise moment of the center of gravity G based on the driving force D is D · d1, and the center of gravity G based on the running resistance f2. The counterclockwise moment of is f2 · d2, and the counterclockwise moment of the center of gravity G based on the driving force F is F2.
・ L. Therefore, the conditional expression in which the vehicle body does not turn due to the driving force F is as follows.

F · L + f2 · d2 = D · d1 From this equation, the above-mentioned equation (2) is derived. In addition, memory 3
5 stores map data M3 indicating the relationship between the driving force D and the driving voltage of the motor 17. From this map data M3, the drive voltage of the motor 17 for obtaining the drive force D that satisfies the above-mentioned expression (2) is obtained.

When moving left and right, that is, the limit switch 19
When the vehicle speed exceeds a predetermined speed, for example, 3 km / h, based on the detection signal from the rotation sensor 37, the MPU 32 disconnects the clutch mechanism 16 and stops driving the motor 17. Has become.

Further, for example, during braking when traveling to the right, braking forces B1 and B2 act on the drive wheel 6 and the road wheel 4, respectively, as shown in FIG. A moment K (= (W + w) βL; where β is deceleration) that acts on the center of gravity G in a clockwise direction by applying a braking force B1 to the drive wheel 6.
The braking force of the brake device 29 is such that the braking force B2 that acts on the road wheel 4 such that a counterclockwise moment of the center of gravity G that suppresses the vehicle body turning is generated so that the vehicle body does not turn. The braking force of the braking device 30 is set to a constant ratio. This ratio was obtained from data from test runs.

Next, the operation of the 4-way forklift 1 will be described. When the vehicle is moving forward and backward, the road wheel 4 is steered in the forward-backward traveling direction (steering angle 0 °) by operating the handlebar lever 11, and the traveling direction is determined by operating the steering wheel 9. At this time, the limit switch 19 is in the off state. Therefore, even if the accelerator lever 12 is operated at the time of starting, only the traveling motor 13 is driven, and the 4-way forklift 1 starts only by the driving force of the drive wheel 6. Further, even if the brake pedal 27 is returned for braking, only the brake device 30 is operated and the 4-way forklift 1 is braked only by the braking force of the brake device 30. That is, the motor 17 and the brake device 29 are not operated during the forward and backward movements in which the vehicle body does not have to turn even if the vehicle is driven and braked only by the drive wheel 6.

Next, for example, when a long load is loaded on the fork 2 and the vehicle body cannot be moved forward or backward due to the passage width, the load is conveyed by moving the 4-way forklift 1 left and right. When moving left and right, first
By operating the steering wheel 9 and the handle lever 11, the road wheel 4 and the drive wheel 6
Are arranged in the left-right direction (steering angle 90 °). As a result, the limit switch 19 turns on and the clutch mechanism 16
Are connected, and the driving force of the motor 17 can be transmitted to the road wheel 4.

When the limit switch 19 is turned on, the MPU 32 executes the program data stored in the memory 35 to obtain the driving voltage of the motor 17, the running resistance f2, the distances L and d1, which are necessary. The calculation for calculating d2 is performed.

First, the MPU 32 has the load cells 21, 2
2 based on the detection signal input from the A / D converter 33, the wheel weights N1 and N applied to the road wheels 4 and 5 respectively.
Calculate 2. Then, with the wheel weight N1 of the road wheel 5,
The running resistance f2 of the road wheel 5 is calculated from the equation (1).

Next, the MPU 32 uses the detection signal input from the pressure sensor 26 and the map data M2 for the fork 2
The load weight w of the upper load is calculated. Then, the distances L, d1 and d2 are calculated from the wheel weights N1 and N2 of the road wheels 4 and 5 and the loaded weight w and the known machine weight W.

Thereafter, when the driver operates the accelerator lever 12 in order to start the 4-way forklift 1 in the left-right direction, the MPU 32 obtains the accelerator opening A from the detection signal input from the potentiometer 36, and the accelerator opening A is set as the accelerator opening A. The traveling motor 13 is driven by a corresponding driving force, and the motor 17 is driven by a driving voltage determined by the driving force D calculated by the equation (2) and the map data M3 according to the accelerator opening A at each moment. Let Therefore, the road wheel 4 is driven with an appropriate driving force D according to the center of gravity position and the running resistance f2 that change depending on the loaded weight on the fork 2 and the reach of the mast 24.

Therefore, at this start, the road wheel 4
Is driven by the driving force D, a conditional expression that prevents the vehicle body turning by the running resistance f2 acting around the center of gravity G, the driving force D, and the moment based on the driving force F, that is, F · L + f2 · d2 = D・ D1 will be satisfied. As a result, even when the 4-way forklift 1 is started in a state where the road wheel 4 and the drive wheel 6 are arranged at a steering angle of 90 °, the vehicle body does not turn, and the vehicle starts smoothly right beside. At this time, since the drive wheel 6 can be arranged in a straight traveling direction (steering angle 90 °) without being cut diagonally to the traveling direction, the drive wheel is slanted to the traveling direction at the time of starting as described in the related art. The wear caused by the skid of the drive tire, which was caused by cutting and handling, is prevented.

The vehicle speed after the start of the 4-way forklift 1 is MP by the detection signal input from the rotation sensor 37.
U32 recognizes and when the vehicle speed exceeds, for example, 3 km / h, the MPU 32 disconnects the clutch mechanism 16 and stops driving the motor 17. That is, the road wheel 4 is driven to prevent the vehicle body from turning only at one time when the vehicle body starts to turn easily, and there is a concern that the vehicle body will turn even if only the driving force F of the drive wheel 6 is applied during traveling. Therefore, the motor 17 is stopped.

Next, the operation of the 4-way forklift 1 during braking will be described. When the 4-way forklift 1 is braked during traveling, the brake pedal 27 is returned. The limit switch 19 is in the ON state during traveling to the left and right.

When the limit switch 19 is in the ON state, the MPU 32 inputs a detection signal corresponding to the amount of return of the brake pedal 27 from the brake switch 28, stops the drive of the traveling motor 13, and causes both brake devices 29, Activate 30. As a result, as shown in FIG. 5, for example, when traveling to the right, the braking force B1 acts on the drive wheel 6 and the braking force B2 acts on the road wheel 4.

Here, the braking force of both brake devices 29 and 30 is set to a constant ratio so that the vehicle body does not turn. Therefore, even if the braking force B1 is applied to the drive wheel 6, the moment K (= (W
+ W) βL) exerts a braking force B2 on the road wheel 4 so that the vehicle body does not turn. as a result,
Even if the vehicle is relatively strongly braked when moving to the left or right, the 4-way forklift 1 stops smoothly while maintaining the body posture without turning the body. Therefore, it is not necessary to return the brake pedal 27 early to slowly brake the vehicle so as to prevent the vehicle body from turning during braking. As a result, the average traveling speed for transportation work is increased, and work efficiency is improved.

As described above in detail, in this embodiment,
The effects listed below can be obtained. (A) Since the road wheel 4 is driven, even when the wheels 4 and 6 are arranged in the left-right traveling direction (steering angle 90 °) at the time of starting in the left-right traveling direction, 4 The way forklift 1 can be started smoothly. As described above, since it is not necessary to cut the drive wheel 6 obliquely with respect to the traveling direction in actual work, it is possible to prevent wear of the tire due to skidding at the start of the drive wheel 6 as described in the prior art. Also, it is possible to prevent meandering traveling due to correction of the course after starting.

(B) Since the driving force D of the road wheel 4 is set by the calculation by the MPU 32 so that the vehicle body does not turn, the vehicle is surely steered in the steering direction even when the vehicle is started in an oblique direction or a lateral direction. Can be started.

(C) As for the driving force D of the road wheel 4, the moment around the center of gravity G based on the driving force D is the moment around the center of gravity G based on the running resistance f2 of the road wheel 5 and the driving wheel 6. M to be the same as the sum of the moment around the center of gravity G based on the driving force F,
Sequentially set by calculation by PU32. Therefore, the driving force D of the road wheel 4 is set by calculating the actual moment that changes due to the movement of the center of gravity of the main forces F and f2 that are considered to contribute to the turning of the vehicle body. The turning can be suppressed.

(D) The steering angle of the road wheel 4 is approximately 90.
The road wheel 4 is driven only when the vehicle is moving left and right, and is not driven when the vehicle is relatively infrequently used diagonally or when there is no concern about turning the vehicle. Therefore, at the time of left-right traveling, which is frequently used and in which the vehicle body turning is most likely to occur at the time of starting, it is possible to at least surely start the vehicle without turning. Further, since the motor 17 is driven only when moving in the left / right direction, the power consumption of the motor 17 can be reduced and the useful life of the motor 17 can be extended.

(E) Since the drive of the road wheel 4 is stopped when the vehicle speed after starting has reached the level where there is no fear of turning of the vehicle body, for example, 3 km / h, the power consumption of the motor 17 can be further reduced and the motor The service life of 17 can be further extended.

(F) Since the brake device 29 is mounted so that the road wheel 4 is also braked when the drive wheel 6 is braked, the 4-way forklift 1 is braked smoothly without turning the vehicle body when braking while moving left and right. be able to. As a result, it is possible to avoid a decrease in the average traveling speed due to early braking that was conventionally performed in actual work, and it is possible to improve work efficiency.

(G) Since the braking force B1 of the road wheel 4 is set so as not to turn the vehicle body, the vehicle can be surely braked smoothly without turning the vehicle body even when the vehicle is braked when moving left and right. it can.

(H) The steering angle of the road wheel 4 is approximately 90.
Since the road wheel 4 is braked only when moving to the left and right, which is relatively frequently used at 0 °, it is possible to extend the service life of the brake device 29 used for the braking.

(I) Since the motor 17 for driving the road wheel 4 and the brake device 29 for braking the road wheel 4 are both provided, the vehicle body can be started and braked when the 4-way forklift 1 travels left and right. It can be done smoothly without turning.

The present invention is not limited to the above embodiment, but may be configured as follows, for example, within the scope of the invention. (1) As shown in FIG. 8, the wheel-in motor 38 is housed in the center of the road wheel 4 and the brake device 39 is attached to the side of the wheel-in motor 38.
The road wheel 4 may be driven by 8 and the road wheel 4 may be braked by the brake device 39. According to this structure, even if the road wheel 4 is equipped with a drive motor and a brake device, the housing 1
The inside of 4 is compact.

(2) As shown in FIG. 1, parameters such as the friction coefficient μ used in the calculation formula f2 = F (N1) of the formula (1) for calculating the running resistance f2 (coefficient of wheel load N1) To
A selection switch 40 as a parameter changing unit may be provided so that the selection can be made according to the road surface used. For example, a plurality of parameters for each road surface such as asphalt, concrete, linoleum, etc. are prepared in the memory 35, and for example, when the vehicle is delivered, a serviceman selects the selection switch 40 to adjust the parameters according to the road surface used. Also, even with the same asphalt, there are differences in road surface roughness, so it is advisable to prepare parameters for each road surface roughness in multiple stages. According to this configuration, since the running resistance f2 that is close to the actual value for each used road surface is calculated by selecting the parameter according to the used road surface, the road wheel with the appropriate driving force D corresponding to the used road surface. 4 can be driven. For example, it is possible to reliably avoid the problem that the vehicle body turns when the vehicle starts in the left-right direction due to the fact that the actual road surface used is different from the preset average road surface used. The selection switch 40 may of course be selectable by the driver.

(3) In place of the limit switch 19, a potentiometer capable of detecting the steering angle of the road wheel 4 is installed.
The driving force between the road wheel 4 and the drive wheel 6 may always be appropriately distributed within the steering angle range. Here, the steering angle θ is considered for the moment when the driving force D is calculated (cos (90−θ) is multiplied to each moment when the vehicle is moving left and right (steering angle 90 °)). According to this configuration, the four-way forklift 1 can be smoothly started in the steering direction not accompanied by turning of the vehicle body, not only when the vehicle is moving left and right but also when it is obliquely started. Of course, the limit switch and the potentiometer are not limited as long as they have the same detection ability.

(4) An inclination angle sensor for detecting the attitude of the vehicle body is provided, and the vehicle body inclination angle obtained from the detection signal from the inclination angle sensor is used as a parameter in the equation for calculating the running resistance f2, which works in the descending direction of the inclined road surface. Running resistance f considering gravity factor
2 may be calculated. According to this configuration,
Appropriate driving force distribution can be realized even when the vehicle starts on an inclined road surface, and the 4-way forklift 1 can always smoothly start in the steering direction regardless of the inclination of the road surface.

(5) The driving force D may be a constant value that satisfies the condition that the vehicle body does not turn. For example, it may be set to a constant value that satisfies the condition that the vehicle body cannot turn when the vehicle is started in the left-right direction at the maximum load and the maximum reach. In addition, the traveling motor 1
The motor 17 may be driven and controlled according to the accelerator opening A so that the output torque has a constant ratio with respect to the output torque of No. 3. According to this configuration, it is not necessary to perform the calculation process for calculating the drive voltage of the motor 17 which involves the calculation process of the drive force D by the MPU 32.

(6) In the above embodiment and the other example (1), the road wheel 4 is equipped with the brake devices 29 and 39. However, without the brake device, the rotation braking of the motor 17 or the plugging braking is performed. The road wheel 4 may be braked. Even with these relatively small braking forces, there is no problem as long as the vehicle body does not turn during braking. According to this configuration, the brake device can be omitted, and the vehicle can be started and braked with a simpler configuration while maintaining the vehicle body posture in the steering direction.

(7) The method of calculating the driving force D is not limited to the equation (2). For example, the running resistance of the caster wheels 7 and the turning resistance of the road wheels 5 and the caster wheels 7 may be taken into consideration.

(8) The driving force for driving the drive wheel 6 may be detachably transmitted to the road wheel 4 via a drive shaft, a clutch or the like. In this case, the clutch may be engaged when it is desired to drive the road wheel 4. Alternatively, the road wheel 4 may be always driven together with the drive wheel 6 without using the clutch. According to this configuration, it is not necessary to provide a dedicated motor for driving the road wheel 4.

(9) The brake device of the road wheel 4 may be a mechanical type that is operated via a link or a wire in response to the operation of the brake pedal 27. (10) The steering angle range in which the road wheel 4 is driven may be different from the steering angle range in which the road wheel 4 is braked. (11) Motor 17 for driving the road wheel 4
It has a structure that does not have a braking means, but only a driving device such as 4), so that it can smoothly move in the steering direction without turning the vehicle body when starting.
The purpose may be only to start the way forklift 1.

(12) Only the braking means for braking the road wheel 4 is provided without a drive device such as the motor 17 for driving the road wheel 4, and the 4-way smoothly without turning the vehicle body during braking. The purpose may be only to brake the forklift 1.

(13) The braking system need not be the deadman system. It is a very good structure that brakes when you press the brake pedal. (14) The invention is not limited to a three-wheel four-way forklift. For example, a four-wheel type may be used.

(15) The road wheel 5, which is the front wheel on the drive wheel 6 side, may be a steered wheel. (16) Industrial vehicles are not limited to 4-way forklifts. The present invention may be applied to other industrial vehicles in which either one of the two front wheels is a steered wheel and the rear wheels have steerable drive wheels.

The invention grasped from the above-mentioned embodiment and not described in the scope of the claims will be described below together with the effect thereof. (A) In any one of claims 3 to 6, inclination detection means capable of detecting inclination of the vehicle body is provided, and the traveling resistance required for calculating the driving force of the steered wheels is detected by the inclination detection. The correction means is provided to correct the vehicle body inclination obtained from the means. According to this configuration, it is possible to obtain an appropriate running resistance even when the vehicle is on the sloped road surface, and therefore it is possible to smoothly start the vehicle on the sloped road surface without turning the vehicle body even when the vehicle starts in an oblique direction or a lateral direction.

[0094]

As described above in detail, according to the inventions of claims 1 and 10, since the front steered wheels can be driven, the center of gravity around the center of gravity based on the driving force of the drive wheels which are the rear wheels can be driven. It is possible to smoothly start without turning the vehicle body even when the vehicle is started in an oblique direction or a lateral direction in which the moment is relatively large. As a result, it is possible to prevent tire wear and meandering due to skidding during starting in actual work.

According to the second and tenth aspects of the present invention, since the driving force of the front steered wheels is set by the driving force setting means so that the vehicle body does not turn, when the vehicle is started diagonally or laterally. Even in this case, the vehicle can be reliably started in the steering direction.

According to the third and tenth aspects of the present invention, the driving force of the front steered wheels is changed by the driving force setting means.
The moment acting around the center of gravity of the vehicle based on this driving force becomes equal to the sum of the moment acting around the center of gravity of the vehicle based on the running resistance of the driven front wheels and the moment acting around the center of gravity of the vehicle based on the driving force of the driving wheels. Is set as
Since the driving force of the front steered wheels is set in consideration of the actual moment of the force that is considered to relatively contribute to the turning of the vehicle body, it is possible to more reliably start in the steering direction and to drive the drive wheels. A more appropriate driving force corresponding to the force can be set for the front steered wheels.

According to the invention described in claims 4 and 10, the front steered wheels are driven only when the steering angle of the front steered wheels is within a predetermined angle range in which the vehicle body is relatively easy to turn, and the vehicle body at the time of starting Since it is not driven at a steering angle where there is no worry of turning, the power consumption of the driving means can be reduced and the service life of the driving means can be extended.

According to the fifth and tenth aspects of the present invention, the front steered wheels are driven only when the vehicle starts, and the front steered wheels are driven when the vehicle speed after the start reaches a predetermined speed at which there is no fear of turning the vehicle body. Since the driving means is stopped, the power consumption of the driving means can be reduced and the service life of the driving means can be extended.

According to the sixth and tenth aspects of the present invention, the parameter of the running resistance of the driven front wheels required for setting the driving force of the front steered wheels is selected (changed) according to the road surface condition. With this configuration, the front steered wheels can be driven with an appropriate driving force according to the road surface used, and the vehicle can be smoothly started in the steering direction regardless of the road surface used.

According to the seventh and tenth aspects of the present invention, since the front steered wheels are braked, the vehicle can be smoothly driven without turning while the vehicle is being braked while traveling diagonally or laterally. Can be braked. As a result, it is possible to prevent a decrease in average traveling speed due to early braking in actual work, and it is possible to improve work efficiency.

According to the eighth and tenth aspects of the invention, the braking force of the front steered wheels is set so that the vehicle body does not turn even by a moment acting around the center of gravity of the vehicle based on the braking force of the driving wheels. Therefore, the vehicle can be reliably braked without turning the vehicle body even during braking during traveling in the diagonal direction or the lateral direction.

According to the ninth and tenth aspects of the present invention, the front steered wheel is braked only when the steering angle of the front steered wheel is within a predetermined angle range in which the vehicle body is relatively easy to turn during braking. Since the vehicle is not braked at a steering angle that does not cause the vehicle body to turn, the power consumption of the braking means can be reduced and the service life of the braking means can be extended.

According to the invention described in claim 10, the vehicle can be started and braked without turning the vehicle body, and the effect according to any one of claims 1 to 6 can be achieved. It also has the effect according to any one of claims 7 to 9.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vehicle body posture maintaining device for a 4-way forklift.

FIG. 2 is a plan view of a 4-way forklift.

FIG. 3 is a perspective view showing a drive mechanism of a road wheel.

FIG. 4 is a plan view for explaining how to maintain the vehicle body posture when starting.

FIG. 5 is a plan view for explaining how to maintain the vehicle body posture during braking.

FIG. 6 is a graph showing a relationship between a mast position and front and rear wheel weights.

FIG. 7 is a schematic side view of a 4-way forklift.

FIG. 8 is a perspective view showing a drive mechanism of another example of a road wheel.

FIG. 9 is a schematic plan view of a conventional 4-way forklift.

FIG. 10 is a schematic plan view of the same.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 4-way forklift as an industrial vehicle, 4 ... Road wheel as a steering wheel, 5 ... Road wheel as a driven front wheel, 6 ... Drive wheel as a drive wheel,
Reference numeral 17 ... Motor constituting drive means, 19 ... Limit switch as steering angle detection means, 29 ... Brake device constituting braking means, 32 ... MPU constituting drive means and braking means and drive force setting means, 34 ... a motor drive circuit constituting drive means, 37 ... a rotation sensor as vehicle speed detection means, 40 ... a selection switch as running resistance changing means.

Claims (10)

[Claims] 1. An industrial vehicle having one of two front side steerable wheels and at least one steered wheel which also serves as a drive wheel on the rear side, wherein a drive means for driving the front side steered wheel is provided. Industrial vehicles. 2. The driving means includes driving force setting means for setting the driving force of the front steered wheels such that the vehicle body does not turn due to a moment acting around the center of gravity of the vehicle based on the driving force of the driving wheels. The industrial vehicle according to claim 1, further comprising: 3. The driving force setting means sets a moment around the center of gravity of the vehicle based on the driving force of the front steered wheels,
The front steering is made equal to the sum of the moment around the center of gravity of the vehicle based on the running resistance acting on the driven front wheels other than the front steered wheels and the moment around the center of gravity of the vehicle based on the driving force of the driving wheels. The industrial vehicle according to claim 2, wherein the driving force of the wheels is set. 4. A steering angle detecting means capable of detecting a steering angle of the front steered wheel, wherein the driving means detects that the steering angle of the front steered wheel is within a predetermined angle range. The industrial vehicle according to any one of claims 1 to 3, wherein the front steered wheels are driven only when it is turned on. 5. A vehicle speed detection means is provided, and the drive means is
The industrial vehicle according to any one of claims 1 to 4, wherein driving of the front steered wheels is stopped when the vehicle speed after starting reaches a predetermined speed. 6. A parameter changing unit is provided which can change a parameter of a running resistance of the driven front wheels, which is necessary for the driving force setting unit to set the driving force of the front steered wheels, according to a road surface condition. The industrial vehicle according to any one of claims 3 to 5. 7. An industrial vehicle having one of two front wheels steerable and having at least one steering wheel that also serves as a driving wheel on the rear side, wherein the front steering wheel is braked at least when the driving wheels are braked. Industrial vehicle equipped with a braking means for controlling. 8. The braking force of the front steered wheels braked by the braking means is set so that the vehicle body does not turn due to a moment acting around the center of gravity of the vehicle based on the braking force of the drive wheels. The industrial vehicle according to 7. 9. A steering angle detecting means capable of detecting a steering angle of the front steered wheel, wherein the braking means detects that the steered angle of the front steered wheel is within a predetermined angle range. The industrial vehicle according to any one of claims 7 to 9, wherein the front-side steered wheels are braked only when the above condition occurs. 10. An industrial vehicle comprising the drive means according to any one of claims 1 to 6 and the braking means according to any one of claims 7 to 9.