JP6988280B2 - Reach forklift - Google Patents

Description

The present invention relates to a reach type forklift.

The reach forklift has a pair of left and right front and rear wheels. In the all-way type reach type forklift, when traveling in the lateral movement mode, the moment of force acts around the center of gravity of the machine during deceleration or acceleration, so that the machine is displaced in the left-right direction. If the posture shifts, the operator needs to correct the posture by operating the steering wheel, which causes troublesome operation. In the braking device of the reach type forklift disclosed in Patent Document 1, the posture deviation generated at the time of deceleration of the brake is suppressed by cutting the angle of the front wheels in the direction opposite to the moment.

Japanese Unexamined Patent Publication No. 5-246347

However, although it is possible to suppress the posture shift during braking operation (during braking), the correction angle of the front wheels is uniquely determined (fixed value), and the force to suppress it when traveling at low speed. If it becomes larger, there is a concern that the posture will shift in the direction opposite to the moment. It was necessary for the operator to steer in order to suppress the wobbling of the machine base.

An object of the present invention is to provide a reach type forklift capable of suppressing wobbling of the machine base during acceleration or deceleration to reduce operator steering.

In the invention according to claim 1, the machine stand, a pair of left and right front wheels provided on the front side of the machine stand, and the rear side of the machine stand, in the left-right direction with respect to a straight line passing through the center of gravity of the machine stand in the traveling direction. A single rear wheel provided at a position shifted in the front-rear direction and driven by a traveling motor, an input means for input operation of the traveling direction and speed of the chassis, and a traveling direction input to the input means. A reach-type forklift equipped with a controller for controlling the traveling motor to drive the rear wheels at a speed corresponding to the operation amount of the input means, wherein the rear wheels are on the left side of the chassis. provided on the front wheel steering a motor, the machine base along a left traveling direction of direction of the machine base, which is inputted to said input means for adjusting the steering angle of the left front wheel of said pair of left and right front wheels Accelerates the steering angle of the left front wheel connected to the front wheel steering motor so as to cancel the moment applied around the center of gravity of the machine during acceleration or deceleration from the acceleration information or deceleration information of the machine. Alternatively, the wheel steering angle correction means for correcting the steering angle according to the deceleration is provided, and the wheel steering angle correction means is provided with the pair of left and right front wheels when a clockwise moment is applied around the center of gravity of the machine base. The larger the acceleration or deceleration is, the larger the correction angle is calculated with respect to the straight line connecting the two, while connecting the pair of left and right front wheels when a counterclockwise moment is applied around the center of gravity of the machine. The controller calculates a larger correction angle as it is clockwise with respect to a straight line and the acceleration or deceleration is larger, and the controller corrects the steering angle of the left front wheel connected to the front wheel steering motor to the correction angle. The gist is to control the front wheel steering motor.

According to the first aspect of the present invention, the front wheel steering angle control means is connected to the front wheel steering motor so as to cancel the moment applied around the center of gravity of the chassis during acceleration or deceleration from the acceleration information or deceleration information of the chassis. The front wheels are corrected to the steering angle according to the acceleration or deceleration. Therefore, it is possible to suppress the wobbling of the machine base during acceleration or deceleration and reduce the steering of the operator.

As described in claim 2, the wheel steering angle correction means may correct the steering angle of the left front wheel connected to the front wheel steering motor based on a command acceleration or a command deceleration based on the vehicle speed.

As described in claim 3, the wheel steering angle correction means uses the pair of left and right front wheels and the rear wheels as steering wheels, and the pair of left and right front wheels and the rear wheels face the left and right sides of the machine base. It is advisable to correct the steering angle of the left front wheel connected to the front wheel steering motor only when traveling to the left of the machine base.

According to the present invention, it is possible to suppress the wobbling of the machine base during acceleration or deceleration and reduce the steering of the operator.

Schematic side view showing a reach type forklift. The perspective view which shows by breaking a part of the reach type forklift. (A) and (b) are plan views schematically showing a reach type forklift. An electrical schematic configuration diagram centering on a controller in a reach type forklift. A map showing the relationship between the correction angle and the command acceleration. (A) and (b) are plan views for explaining the behavior of the reach type forklift at the time of acceleration in an embodiment. (A), (b), (c) are plan views for explaining the behavior of the reach type forklift at the time of acceleration in the comparative example. (A) and (b) are plan views for explaining the behavior of the reach type forklift when accelerating and the traveling direction is opposite in the embodiment. (A) and (b) are plan views for explaining the behavior of the reach type forklift at the time of deceleration in the embodiment. (A), (b), (c) are plan views for explaining the behavior of the reach type forklift at the time of deceleration in the comparative example.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the reach type forklift 11 includes a machine base 12. The machine base 12 has a pair of left and right reach legs 13a and 13b extending forward. Specifically, the reach leg 13a is provided on the left side in the traveling direction, and the reach leg 13b is provided on the right side in the traveling direction. Front wheels 14a and 14b are arranged in front of the reach legs 13a and 13b. Specifically, the left front wheel 14a is provided on the reach leg 13a on the left side in the traveling direction, and the right front wheel 14b is provided on the reach leg 13b on the right side in the traveling direction. As described above, a pair of left and right front wheels 14a and 14b are provided on the front side of the machine base 12.

A rear wheel 15 and caster wheels (training wheels) 16 are arranged behind the machine base 12. The rear wheel 15 is provided on the left side of the machine base 12, and the caster wheel 16 is provided on the right side of the machine base 12. Specifically, as shown in FIGS. 3 (a) and 3 (b), the rear wheels 15 are displaced in the left-right direction with respect to the straight lines L10 and L11 passing through the center of gravity 19 of the machine base in the traveling direction on the rear side of the machine base 12. It is provided at the position. That is, the rear wheels 15 are provided with offsets by the distances L1 and L2. The rear wheels 15 are drive wheels and steering wheels.

As shown in FIGS. 1, 3 (a) and 3 (b), the reach type forklift 11 travels on three wheels of two front wheels 14a and 14b and one rear wheel 15 (caster wheel 16). Is omitted). The machine base 12 is equipped with a traveling motor 41 that is a drive source of the reach type forklift 11 and a battery 40 that is a power source of the traveling motor 41. Then, the rear wheels 15 are rotationally driven by the traveling motor 41.

The reach type forklift 11 is provided with a cargo handling device 21 in front of the machine base 12. The cargo handling device 21 includes a mast 22 that moves back and forth along the reach legs 13a and 13b by driving a reach cylinder (not shown). A pair of left and right forks 23a and 23b are provided in front of the mast 22 via a lift bracket 24. The forks 23a and 23b move up and down along the mast 22.

As shown in FIG. 2, the reach type forklift 11 is provided with a standing type driver's cab 31 at the rear of the machine base 12. Steering tables 32a and 32b are provided in front of and to the left of the driver's cab 31. The steering table 32a located in front of the driver's cab 31 is provided with a direction lever 33 for operating the reach type forklift 11, a plurality of cargo handling levers 34 for operating the cargo handling device 21, and a changeover switch 35. The direction lever 33 is operated to rotate the rear wheel 15 to drive the vehicle. The steering table 32b located to the left of the driver's cab 31 is provided with a steering wheel 36 for steering the left and right front wheels 14a and 14b and the rear wheels 15. Further, a brake pedal 37 is provided on the floor surface of the driver's cab 31.

As shown in FIG. 4, the controller 54 has a function of executing various processes in a predetermined procedure, and also includes a storage unit 55 for storing various control information such as a control program. A direction lever sensor 51, a steering wheel operation sensor 52, a vehicle speed sensor 53, a traveling motor 41, a rear wheel steering motor 42, and a left front wheel steering motor 43 are connected to the controller 54. The rear wheel steering motor 42 is for adjusting the steering angle of the rear wheels 15, and the left front wheel steering motor 43 is for adjusting the steering angle of the left front wheels 14a. The controller 54 can control the left front wheel steering motor 43, whereby the steering angle of the left front wheel 14a as the front wheel on the steerable side can be corrected.

The direction lever sensor 51 detects the operation direction of the direction lever 33 and the operation amount of the direction lever 33. The operation direction of the direction lever 33 is a forward instruction direction for advancing the reach type forklift 11 and a reverse instruction direction for advancing the reach type forklift 11. The direction lever sensor 51 outputs an electric signal according to the operation direction and the operation amount of the direction lever 33 to the controller 54. The controller 54 controls the traveling motor 41 to drive the rear wheels 15 at a speed corresponding to the amount of operation toward the traveling direction according to the operation direction of the direction lever 33.

The steering wheel operation sensor 52 is arranged on the steering wheel 36, and detects the operation amount (angle) of the steering wheel 36. The steering wheel operation sensor 52 outputs an electric signal corresponding to the operation amount of the steering wheel 36 to the controller 54. The controller 54 controls the direction of the steering wheel so that the steering angle is set according to the operation amount (angle) of the steering wheel 36.

The reach type forklift 11 can set a standard mode and an all-way mode as a mode for traveling.
The standard mode is a mode in which only the rear wheels 15 are steered wheels. When going straight in the standard mode, as shown in FIG. 3A, the front wheels 14a and 14b and the rear wheels 15 are in a state of facing forward and backward. Only the rear wheels 15 are steered when turning in standard mode. The lateral movement mode in the all-way mode is a mode in which the front wheels 14a and 14b and the rear wheels 15 are used as steering wheels, and the vehicle travels in the lateral (left and right) direction. When traveling straight in the lateral movement mode, the front wheels 14a and 14b and the rear wheels 15 are in a state of facing left and right, as shown in FIG. 3 (b). When turning in the lateral movement mode, the left front wheels 14a and 14b and the rear wheels 15 are steered.

By operating the changeover switch 35, each mode such as the standard mode and the lateral movement mode in the all-way mode can be set.
The map shown in FIG. 5 is stored in the storage unit 55 of the controller 54. In FIG. 5, the horizontal axis represents the command acceleration and the vertical axis represents the correction angle Δθ. As shown in FIG. 6A, the correction angle Δθ is an angle formed by the straight line Lc connecting the left and right front wheels 14a and 14b and the direction Ls of the left front wheel 14a, and the counterclockwise direction is on the minus side. The map of FIG. 5 has a characteristic line L100 that defines a correction angle (correction amount) Δθ of the left front wheel 14a with respect to the command acceleration. In the characteristic line L100, the correction angle Δθ also increases as the command acceleration increases. The correction angle Δθ corresponding to the command acceleration can be calculated using the characteristic line L100.

More specifically, the command acceleration is calculated from the operating state of the direction lever 33 (whether it is trying to accelerate or decelerate), the amount of operation of the direction lever 33, and the current vehicle speed.

When the direction lever 33 is tilted forward, it moves forward, and when the direction lever 33 is tilted backward, it moves backward. As for the relationship between the operation amount of the direction lever 33 and the vehicle speed, the larger the operation amount of the direction lever 33, the higher the vehicle speed. Therefore, if there is a discrepancy between the operation amount of the direction lever 33 and the actual vehicle speed, the vehicle speed is controlled so as to be the vehicle speed according to the operation amount of the direction lever 33.

The characteristic line L100 of FIG. 5 is obtained in advance from the operating state of the direction lever 33, the operating amount of the direction lever 33, and the vehicle speed, and the operating state of the direction lever 33, the operating amount of the direction lever 33, and the vehicle speed. When is determined, the command acceleration is determined. For example, the larger the difference between the operation amount of the direction lever 33 and the vehicle speed, the larger the command acceleration.

Then, the correction angle Δθ of the left front wheel is calculated with respect to the command acceleration calculated in this way using the map of FIG.
In addition, although the map for acceleration with the horizontal axis as the command acceleration is shown in FIG. 5, a map for deceleration (not shown) is also available, and the map for deceleration has a command reduction on the horizontal axis in FIG. Take the speed and the correction angle on the vertical axis takes a positive value.

The controller 54 controls the left front wheel steering motor 43 to obtain a moment M (see FIG. 6A) applied around the center of gravity 19 of the machine base during acceleration or deceleration from the acceleration information or deceleration information of the machine base 12. The left front wheel 14a can be corrected to a steering angle according to acceleration or deceleration so as to cancel out. Specifically, the controller 54 can correct the steering angle of the left front wheel 14a based on the command acceleration or the command deceleration based on the vehicle speed by using the map of FIG.

Next, the operation of the reach type forklift 11 will be described.
As shown in FIGS. 6A and 6B, the controller 54 executes the following processing in the all-way lateral movement mode.

The controller 54 corrects the steering of the left front wheel 14a in the direction of canceling the moment M with reference to the map of FIG. 5 based on the acceleration or deceleration which is the amount of time change of the vehicle speed during acceleration / deceleration during driving. do. That is, as shown in FIG. 6A, when the clockwise moment M is applied, the direction is changed counterclockwise by a predetermined correction angle Δθ with respect to the straight line Lc connecting the front wheels 14a and 14b. At this time, the correction angle Δθ is determined according to the magnitude of the acceleration (the larger the acceleration, the larger the correction angle Δθ). As a result, the vehicle moves linearly as shown in FIG. 6 (b). As a result, unnecessary steering wheel operation by the operator is unnecessary or the steering wheel operation by the operator is reduced, leading to improved work.

The behavior of the reach type forklift during acceleration in the comparative example will be described with reference to FIGS. 7A, 7B, and 7C.
As shown in FIG. 7 (a), when accelerating from a stop or accelerating by switchback (an operation of moving forward to reverse or backward to forward by operating the direction lever 33), as shown in FIG. 7 (b). Because of the rear wheel drive, the attitude shifts due to the clockwise moment M of the force centered on the center of gravity 19 of the machine base. Therefore, as shown in FIG. 7 (c), the operator needs to correct the machine base direction by operating the steering wheel so as to go straight.

The behavior of the reach type forklift 11 at the time of acceleration in this embodiment will be described with reference to FIGS. 6 (a) and 6 (b).
As shown in FIG. 6A, the correction of the left front wheel 14a according to the acceleration in the direction of canceling the clockwise moment M from the acceleration information of the machine base 12, that is, counterclockwise from the straight line Lc which is the reference line. The angle Δθ is calculated, and the left front wheel 14a is steered with the corrected left front wheel steering amount. By doing so, as shown in FIG. 6B, it is possible to go straight without or while reducing the operator's steering wheel operation.

Further, the steering angle of the left front wheel 14a is corrected only when the rear wheel 15 is facing in the straight direction. This is because when there is an intention to turn, it turns without any discomfort. In other words, by monitoring the movement of the rear wheels 15, which are the steering wheels, the operator wants to keep the posture straight when running straight, but when trying to turn the chassis, the steering angle of the left front wheel 14a. No correction is performed (correction is made only when going straight in the horizontal movement mode).

In addition, although it is the case of traveling to the left in FIGS. 6 (a) and 6 (b), as shown in FIGS. 8 (a) and 8 (b), the relationship between the correction angle and the acceleration is obtained even when traveling to the right. Does not change. That is, the relationship between the correction angle and the acceleration does not change even when the traveling direction at the time of acceleration is opposite (regardless of the traveling direction).

In the correction at the time of deceleration, the correction amount of the steering angle of the left front wheel 14a according to the deceleration in the direction of canceling the moment is calculated at the time of deceleration as well as at the time of acceleration.
The behavior of the reach type forklift during deceleration in the comparative example will be described with reference to FIGS. 10A, 10B, and 10C.

As shown in FIG. 10 (a), during deceleration, as shown in FIG. 10 (b), the attitude is displaced by the counterclockwise moment M of the force centered on the center of gravity 19 of the machine base for rear wheel drive. Therefore, as shown in FIG. 10 (c), the operator needs to correct the machine base direction by operating the steering wheel so as to go straight.

The behavior of the reach type forklift during deceleration in the present embodiment will be described with reference to FIGS. 9 (a) and 9 (b).
As shown in FIG. 9A, the correction angle Δθ according to the deceleration is calculated from the deceleration information of the machine base in the direction of canceling the counterclockwise moment M, and the left front wheel 14a is steered. By doing so, as shown in FIG. 9B, it is possible to go straight without or while reducing the operator's steering wheel operation.

In this way, unnecessary or unnecessary steering wheel operation by the operator during acceleration / deceleration can be unnecessary or reduced, leading to improved work. In addition, since the machine base does not wobble, stable acceleration / deceleration running is possible even in a narrow passage.

That is, in an all-way type reach type forklift, the steering angle of the left front wheel 14a is adjusted according to the degree of acceleration / deceleration for the attitude deviation caused by the moment of the force centered on the center of gravity 19 of the machine during acceleration and deceleration. Suppressed by. Specifically, in the all-way type reach type forklift, when traveling in the lateral movement mode, the moment of force acts around the center of gravity of the machine during brake deceleration or acceleration, so that the machine is displaced in the left-right direction. If the posture shifts, the operator needs to correct the posture by operating the steering wheel, which causes troublesome operation. On the other hand, in the present embodiment, the left front wheel 14a is steered during brake deceleration or acceleration to reduce the attitude shift (machine base shift) without the operator operating the steering wheel (or the reduction of the steering wheel operation). ) Improves workability.

According to the above embodiment, the following effects can be obtained.
(1) As a configuration of the reach type forklift 11, a machine base 12, a pair of left and right front wheels 14a and 14b provided on the front side of the machine base 12, and a machine base center of gravity 19 in the traveling direction are provided on the rear side of the machine base 12. A rear wheel 15 is provided at a position shifted in the left-right direction with respect to the straight lines L10 and L11 passing through, and is driven by a traveling motor 41. Further, wheel steering that corrects the left front wheel 14a to a steering angle according to acceleration or deceleration so as to cancel the moment applied around the center of gravity 19 of the machine during acceleration or deceleration from the acceleration information or deceleration information of the machine base 12. A controller 54 as an angle correction means is provided. Therefore, it is possible to suppress the wobbling of the machine base during acceleration or deceleration and reduce the steering of the operator.

(2) The controller 54 as the wheel steering angle correction means corrects the steering angle of the left front wheel 14a based on the command acceleration or the command deceleration based on the vehicle speed. Therefore, it is practical.
(3) The controller 54 as the wheel steering angle correction means corrects the steering angle of the left front wheel 14a as the front wheel on the steerable side. Therefore, it is practical.

(4) The controller 54 as the wheel steering angle correction means corrects the wheel steering angle only when the rear wheels 15 are facing in the straight-ahead direction. Therefore, when there is an intention to turn, it is possible to turn without discomfort.

The embodiment is not limited to the above, and may be embodied as follows, for example.
○ Since the rear wheels of the reach type forklift are offset, the steering angle of the left front wheel 14a is corrected not only in the lateral movement mode where the moment of force with respect to the center of gravity 19 of the machine is most affected, but also during acceleration / deceleration during standard driving. You may.

○ The wheel for corrective steering was the left front wheel 14a, but it is not limited to this. The wheel for corrective steering may be the right front wheel 14b or the rear wheel 15. When the right front wheel 14b is corrected and steered, the controller 54 controls the right front wheel steering motor 44 as shown by a virtual line in FIG. Further, the wheel for corrective steering is not one wheel, but may be two wheels or three wheels. In short, at least one of the pair of left and right front wheels and rear wheels may be corrected. Further, when correcting a plurality of wheels, different values may be calculated for the correction amount of the plurality of wheels.

○ Correction may be performed only when accelerating. In addition, correction may be performed only during deceleration.

11 ... reach type forklift, 12 ... machine stand, 14a ... left front wheel, 14b ... right front wheel, 15 ... rear wheel, 19 ... machine center of gravity, 54 ... controller, Lc ... straight line, M ... moment.

Claims (3)

With the machine stand
A pair of left and right front wheels provided on the front side of the machine base,
A single rear wheel provided on the rear side of the machine base at positions deviated from the straight line passing through the center of gravity of the machine machine in the traveling direction in the left-right direction and the front-rear direction and driven by a traveling motor.
An input means for inputting the traveling direction and speed of the machine base, and
A reach-type forklift equipped with a controller for controlling the traveling motor to drive the rear wheels at a speed corresponding to the operation amount of the input means toward the traveling direction input to the input means.
The rear wheel is provided on the left side of the machine stand, and the rear wheel is provided on the left side of the machine stand.
A front wheel steering motor that adjusts the steering angle of the left front wheel of the pair of left and right front wheels,
Around the machine base center of gravity during acceleration or deceleration from the machine base acceleration information or deceleration information when traveling the machine base along a left traveling direction of direction of the machine base, which is inputted to the input means A wheel steering angle correction means for correcting the steering angle of the left front wheel connected to the front wheel steering motor so as to cancel the moment applied to the steering angle according to acceleration or deceleration.
The wheel steering angle correction means is counterclockwise with respect to a straight line connecting the pair of left and right front wheels when a clockwise moment is applied around the center of gravity of the machine base, and the larger the acceleration or deceleration, the larger the correction angle. On the other hand, when a counterclockwise moment is applied around the center of gravity of the machine, a larger correction angle is calculated as the acceleration or deceleration is larger in the clockwise direction with respect to the straight line connecting the pair of left and right front wheels. ,
The controller is a reach type forklift that controls the front wheel steering motor so that the steering angle of the left front wheel connected to the front wheel steering motor is corrected to the correction angle. The reach-type forklift according to claim 1, wherein the wheel steering angle correcting means corrects the steering angle of the left front wheel connected to the front wheel steering motor based on a command acceleration or a command deceleration based on the vehicle speed. .. The wheel steering angle correction means, proceeds the pair of left and right front wheels and the rear wheel as the steering wheel, to the left of the machine base in a state where the pair of left and right front wheels and the rear wheels facing left and right of the machine base The reach type forklift according to claim 1 or 2, wherein the steering angle of the left front wheel connected to the front wheel steering motor is corrected only when the steering wheel is operated.

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