JP2004075217A - Forklift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forklift which enables a driver to constantly travel in an intending direction, and is provided with a drive wheel which can be steered in 360°. <P>SOLUTION: The forklift 21 with the drive wheel which can be steered in 360° comprises a travelling direction selecting means 23 for selecting a travelling direction of the forklift, steering angle detecting means 6, 38 for detecting a steering angle of the drive wheel, and a travel control means 2 for determining a rotation direction of the drive wheel based on the travelling direction and the steering angle of the drive wheel when the travelling direction is selected by the travelling direction selecting means, and controlling so that the forklift travels in the selected travelling direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a forklift provided with drive wheels capable of being steered by 360 °.
[0002]
[Prior art]
Conventionally, a seat-type reach-type forklift (hereinafter simply referred to as a forklift) 21 as shown in FIG. 6 has been used. The driver sits on the seat 22 of the forklift 21, operates the steering wheel 25 with the left hand, and operates the directional switch 23 shown in FIG. 7 provided on the driving console 29 with the right hand to change the traveling direction of the forklift 21. Control. In addition, the driver controls the rotation speed of the traveling motor, that is, the traveling speed of the forklift 21 by adjusting the amount of depression of an accelerator pedal provided on the floor 26 of the forklift 21.
[0003]
In such a forklift 21, the steering angle of the drive wheel 24 is limited by a stopper so as to fall within a range of ± 90 ° with respect to the forward direction of the forklift 21. Some wheels 24 are provided so that they can be steered by 360 °. In the former, the tilt direction of the directional switch 23 and the rotation direction of the traveling motor that drives the drive wheels 24 are uniquely set. For example, the directional switch 23 is viewed from the front of the forklift 21, that is, when viewed from the driver. When tilted forward, the traveling motor rotates forward and the forklift 21 moves forward. Also, in the latter case, the tilting direction of the directional switch 23 and the rotation direction of the traveling motor may be uniquely set by applying the former configuration as it is.
[0004]
8 to 12 show the state of the forklift 21 when the driver gradually rotates the steering wheel 25. FIG. However, for convenience of explanation, the forklift 21 in FIGS. 8 to 12 is simplified. FIGS. 8 to 12 also show that the directional switch 23 is tilted to the black triangle of the two triangles representing the directional switch 23. When the directional switch 23 is tilted in the forward direction of the forklift 21, that is, toward the front side as viewed from the driver, the traveling motor rotates forward and the drive wheels 24 rotate forward, and the directional switch 23 rotates. When the vehicle is tilted backward in the forklift 21, that is, backward when viewed from the driver, the driving motor rotates in reverse and the drive wheels 24 rotate in reverse.
[0005]
FIG. 8 shows a case where the steering angle of the forklift 21 with respect to the forward direction is 0 ° in a state where the drive wheel 24 is rotating forward, and the forklift 21 advances straight forward as indicated by an arrow. FIG. 9 shows a case where the steering angle is −45 ° in a state where the drive wheel 24 is rotating forward, and as indicated by the arrow, the forklift 21 advances obliquely rightward and forward 45 °. FIG. 10 illustrates a case where the steering angle is −90 ° in a state where the drive wheel 24 is rotating forward, and as indicated by the arrow, the forklift 21 is located at the midpoint between the two rear driven wheels 27a and 27b. Turn right around the vehicle. FIG. 11 shows a case where the steering angle is −135 ° in a state where the drive wheel 24 is rotating forward, and as indicated by the arrow, the forklift 21 advances in a direction obliquely to the right and 45 ° behind. FIG. 12 shows a case where the steering angle is −180 ° (or 180 °) in a state where the drive wheel 24 is rotating forward, and the forklift 21 goes straight backward as indicated by the arrow.
[0006]
As described above, in the forklift 21 in which the drive wheels 24 can be steered by 360 °, the driver can freely change the traveling direction of the forklift 21 only by operating the handle 25, so that the steering angle of the drive wheels 24 is limited by the stopper. There is an advantage that the operability is higher than that which is performed.
[0007]
[Problems to be solved by the invention]
As shown in FIGS. 8 to 12, when the steering angle of the drive wheel 24 is within −90 °, the tilt direction of the directional switch 23 and the traveling direction of the forklift 21 match, but the steering angle is −180 °. When the angle is between -90 °, the tilting direction of the directional switch 23 and the traveling direction of the forklift 21 are opposite.
[0008]
When the forklift 21 is once stopped to perform the cargo handling operation and is to be moved again, or when the driver is changed, the driver determines that the directional switch 23 is tilted and the traveling of the forklift 21 In such a case, it may not be possible to determine whether the directions match, and in such a case, the direction switch 23 is tilted in a direction in which the forklift 21 is intuitively driven without considering the steering angle of the drive wheel 24. Sometimes. For example, in the forklift 21 described above, it is conceivable that the direction switch 23 is tilted to the front side in order to move the forklift 21 forward. Will go backwards. When the forklift travels in a direction opposite to the driver's intention in this way, not only is there a danger to the surroundings, but there is also a risk that the driver will be confused and further driving errors will be caused.
[0009]
Therefore, an object of the present invention is to provide a forklift in which drive wheels are provided so as to be able to steer 360 °, which can always drive in a direction intended by a driver.
[0010]
[Means to solve the problem]
In order to achieve the above object, the present invention provides a forklift provided with a drive wheel that can be steered by 360 °, a driving direction selecting means operated by a driver to select a driving direction of the forklift, and the driving wheel A steering angle detecting means for detecting a steering angle of the vehicle, and when a traveling direction is selected by the traveling direction selecting means, a rotation direction of the drive wheel is determined based on the traveling direction and the steering angle, and the selection is made. Traveling control means for controlling the forklift to travel in the set traveling direction.
[0011]
When the driver operates the traveling direction selection means to select the traveling direction of the forklift, the selected traveling direction is input to the traveling control means. Further, the steering angle of the drive wheel detected by the steering angle detecting means is also input to the traveling control means. The travel control means determines the rotation direction of the drive wheel so that the forklift travels in the input travel direction. When the driver instructs the vehicle to run, for example, by depressing an accelerator pedal, the drive wheels are driven in the rotation direction of the drive wheels determined by the travel control means, and the driver selects the forklift. Travel in the traveling direction. That is, the traveling direction selected by the driver using the traveling direction selection means always coincides with the actual traveling direction of the forklift.
[0012]
The traveling direction selecting means can select either forward or backward as the traveling direction of the forklift, and the steering angle detecting means can detect the steering angle of the drive wheel in the range of -180 ° to 180 ° with respect to the forward direction of the forklift. In such a configuration, the traveling control means includes:
In the state where the steering angle detecting means detects the steering angle within ± 90 ° with respect to the forward direction of the forklift, when the forward direction is selected by the traveling direction selecting means, the rotation direction of the drive wheel is rotated forward. The direction of rotation of the drive wheels is determined when the traveling direction selection unit selects reverse when the steering angle is within ± 90 ° with respect to the forward direction of the forklift by the steering angle detection unit. Is the reverse direction, and in the state where the steering angle of 90 ° to 180 ° or −180 ° to −90 ° with respect to the forward direction of the forklift is detected by the steering angle detecting means, the forward direction is selected by the traveling direction selecting means. When selected, the rotation direction of the drive wheel is set to the reverse rotation direction, and the steering angle detection means sets the rotation direction of the drive wheel at 90 ° to 180 ° or −18 ° with respect to the forward direction of the forklift. In a state where the steering angle ° from -90 ° is detected, when the reverse is selected by the traveling direction selection means it may be a rotational direction of the drive wheel to the forward direction.
[0013]
With this configuration, the driver can select forward to move the forklift forward, and select reverse to move the forklift backward without performing the operation while considering the steering angle of the drive wheel. . Also, when forward or reverse is selected by the traveling direction selecting means, the traveling control means determines the rotation direction of the drive wheels to be the forward direction or the reverse direction. However, the drive wheel is driven in the determined rotation direction unless forward or reverse is selected again, so that the drive wheel that can change the traveling direction of the forklift only by operating the steering wheel is provided to be able to steer 360 °. The characteristics inherent in the forklift are not impaired.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a seat-type reach-type forklift will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a functional block diagram of a traveling drive system provided in the forklift according to the present embodiment, FIG. 2 is a partial cross-sectional view illustrating a main part of the forklift according to the present embodiment, and FIG. FIG. 4 is an explanatory diagram showing a steering angle detecting means according to the present embodiment, and FIG. 5 is a flowchart for determining a control mode of the traveling motor according to the present embodiment. Note that the overall configuration of the forklift 21 in the present embodiment is the same as that of the prior art shown in FIGS. 6 and 7, and therefore, the same reference numerals are given and detailed description is omitted.
[0016]
The drive wheels 24 provided in the forklift 21 of this embodiment are driven by the traveling motor 3 shown in FIG. 1, and the traveling motor 3 is controlled by the traveling control means 2. The travel control means 2 includes a signal indicating the tilt direction of the directional switch 23 output from the directional switch 23 as the travel direction selection means, and a drive wheel 24 output from the limit switch 6 serving as the steering angle detection means. A signal corresponding to the steering angle is input. Then, based on the input signal indicating the tilt direction of the directional switch 23 and the signal corresponding to the steering angle of the drive wheel 24, the travel control means 2 rotates the travel motor 3 as described in detail below. By controlling the direction, the rotation direction of the drive wheel 24 is controlled. Further, a signal indicating the amount of depression of the accelerator pedal 7 is also input to the traveling control means 2, and the traveling control means 2 uses the traveling motor 3 based on the signal indicating the amount of depression of the accelerator pedal 7. Is controlling the rotation speed. The directional switch 23 is provided so as to be tiltable in the front-rear direction of the forklift 21. When the forklift 21 is tilted forward, a signal indicating that the directional switch 23 is tilted forward is a signal. When the forklift 21 is tilted rearward, a signal indicating that the direction of tilt of the directional switch 23 is rearward is output. Further, the directional switch 23 has a built-in spring for returning to a neutral state where the directional switch 23 is not tilted. It returns to a neutral state.
[0017]
FIG. 2 shows a driving mechanism and a steering mechanism of the driving wheels 24. The rotation of the traveling motor 3 is transmitted to the gear box 37 via the drive shaft A, and then transmitted to the drive wheels 24 supported by the gear box 37. With such a driving mechanism, when the traveling motor 3 rotates forward, the driving wheels 24 rotate forward, and when the traveling motor 3 rotates reversely, the driving wheels 24 rotate reversely. On the other hand, the rotation of the steering motor 34 is transmitted to a steering gear 35 fixed to a gear box 37 via a reduction gear 36. When the steering gear 35 rotates, the drive wheels 24 are steered together with the gear box 37. Note that the steering gear 35 and the drive shaft A are arranged coaxially. A projection 38 is formed on the upper surface of the steering gear 35, and the lever of the limit switch 6 comes into contact with the projection 38.
[0018]
Here, as shown in FIG. 3, an inner angle formed by a forward direction of the forklift 21 and a direction B in which the forklift 21 travels by the driving wheel 24 when the driving wheel 24 is driven in the normal rotation direction by the traveling motor 3. θ is the steering angle of the drive wheel 24. Then, a state in which the forward direction of the forklift 21 matches the above-mentioned direction B is defined as a steering angle θ = 0 °, and the steering on which the drive wheel 24 is steered counterclockwise in plan view from the steering angle θ = 0 °. The angle θ is represented by a positive value, and the steering angle θ on the side steered clockwise is represented by a negative value. The steering mechanism provided in the forklift 21 according to the present embodiment does not include a stopper or the like that limits the steering angle θ of the drive wheel 24, so that the drive wheel 24 can be steered by 360 °. The possible value of the steering angle θ of the drive wheel 24 is in the range of −180 ° <θ ≦ 180 ° (Since the steering angle θ = −180 ° and the steering angle θ = 180 ° are the same, the steering angle is set here. Angle θ = 180 °).
[0019]
The projection 38 formed on the upper surface of the steering gear 35 has a semi-cylindrical shape as shown in FIGS. 4A and 4B, and the steering angle θ of the drive wheel 24 is −180 ° <θ <−90. When the angle is in the range of 90 ° or 90 ° <θ ≦ 180 °, the lever of the limit switch 6 comes into contact with the projection 38 to be turned on, and the steering angle θ of the drive wheel 24 becomes −90 ° ≦ θ ≦ 90. When it is in the range of °, the limit switch 6 is turned off. The limit switch 6 and the projection 38 constitute the steering angle detecting unit 5, and an ON signal from the limit switch 6 is input to the traveling control unit 2.
[0020]
In the above configuration, when the driver steers the steering wheel 25, the steering motor 34 rotates the reduction gear 36 according to the operation angle of the steering wheel 25, so that the steering gear 35 interlocked with the reduction gear 36 rotates. As described above, when the steering gear 35 rotates with the operation of the steering wheel and the steering angle θ of the drive wheel 24 falls within the range of −180 ° <θ <−90 ° or 90 ° <θ ≦ 180 °, the projection 38 is switched to the limit switch. By pushing up the lever 6, the limit switch 6 is turned on. Then, when the ON signal of the limit switch 6 is input to the travel control means 2, the travel control means 2 sets the steering angle θ of the drive wheel 24 to -180 ° <θ <-90 ° or 90 ° <θ ≦ 180 °. It is determined that it is within the range. Conversely, if the limit switch 6 is off and the on signal is not input, the traveling control means 2 determines that the steering angle θ of the drive wheel 24 is in the range of −90 ° ≦ θ ≦ 90 °.
[0021]
Hereinafter, the control procedure according to the present embodiment will be described with reference to FIG.
First, the traveling control means 2 determines the state of the limit switch 6 (S1). When the travel control means 2 determines that the state of the limit switch 6 is off, the travel control means 2 then determines whether or not the signal indicating the travel direction input from the directional switch 23 to the travel control means 2 is a forward direction ( S2).
[0022]
If it is determined in step S2 that the vehicle is in the forward direction, the traveling control means 2 sets the control mode of the traveling motor 3 to the forward rotation mode, and controls the traveling motor 3 in the forward rotation mode (S3). If it is determined in step S2 that the traveling direction is not the forward direction, then it is determined whether the signal indicating the traveling direction input from the directional switch 23 to the traveling control means 2 is the backward direction (S4).
[0023]
If it is determined in step S4 that the vehicle is in the backward direction, the traveling control means 2 sets the control mode of the traveling motor 3 to the reverse rotation mode, and controls the traveling motor 3 in the reverse rotation mode (S5). If it is determined in step S4 that the directional switch 23 is not in the backward direction, the tilting direction of the directional switch 23 is neither the forward direction nor the backward direction, that is, the directional switch 23 is in a neutral state in which the directional switch 23 is not tilted. The means 2 does not set the control mode again, so that the current control mode is maintained.
[0024]
On the other hand, if it is determined in step S1 that the state of the limit switch 6 is ON, then it is determined whether or not the signal indicating the traveling direction input from the directional switch 23 to the traveling control means 2 is the forward direction (S6). ).
[0025]
If it is determined in step S6 that the vehicle is in the forward direction, the traveling control means 2 sets the control mode of the traveling motor 3 to the reverse rotation mode, and controls the traveling motor 3 in the reverse rotation mode (S5). If it is determined in step S6 that the traveling direction is not the forward direction, then it is determined whether the signal indicating the traveling direction input from the directional switch 23 to the traveling control means 2 is the backward direction (S7).
[0026]
If it is determined in step S7 that the vehicle is in the backward direction, the travel control means 2 sets the control mode of the travel motor 3 to the normal rotation mode, and controls the travel motor 3 in the normal rotation mode (S3). If it is determined in step S7 that the directional switch 23 is not in the rearward direction, the tilting direction of the directional switch 23 is neither the forward direction nor the rearward direction, that is, the directional switch 23 is in a neutral state in which the directional switch 23 is not tilted. The means 2 does not set the control mode again, so that the current control mode is maintained.
[0027]
The change from the normal rotation mode to the reverse rotation mode or the change from the reverse rotation mode to the normal rotation mode is performed by switching the polarity of the traveling motor 3.
[0028]
By the way, when the accelerator pedal 7 is depressed, the traveling control means 2 applies a voltage corresponding to the depression amount to the traveling motor 3. For example, the accelerator pedal 7 is depressed in the normal rotation mode. When the accelerator pedal 7 is depressed in the reverse rotation mode, the travel control means 2 reversely rotates the travel motor 3.
[0029]
When the driver tilts the directional switch 23 in the forward direction and depresses the accelerator pedal 7 when the steering angle θ of the drive wheel 24 is in the range of −90 ° ≦ θ ≦ 90 ° (the limit switch 6 is in the off state), The traveling control means 2 controls the traveling motor 3 in the normal rotation mode, and the forklift 21 moves forward. When the steering angle θ of the drive wheel 24 is in the range of −180 ° <θ <−90 ° or 90 ° <θ ≦ 180 ° (the limit switch 6 is in the on state), the directional switch 23 is tilted forward. When the accelerator pedal 7 is depressed, the traveling control means 2 controls the traveling motor 3 in the reverse rotation mode, and the forklift 21 moves forward.
[0030]
On the other hand, when the steering angle θ of the drive wheel 24 is in the range of −90 ° ≦ θ ≦ 90 ° (the limit switch 6 is in the off state), the driver tilts the directional switch 23 backward and depresses the accelerator pedal 7. And the traveling control means 2 controls the traveling motor 3 in the reverse rotation mode, and the forklift 21 moves backward. When the steering angle θ of the drive wheels 24 is in the range of −180 ° <θ <−90 ° or 90 ° <θ ≦ 180 ° (the limit switch 6 is in the on state), the directional switch 23 is tilted backward. When the accelerator pedal 7 is depressed, the traveling control means 2 controls the traveling motor 3 in the normal rotation mode, and the forklift 21 moves backward.
[0031]
As described above, according to the present embodiment, the forklift 21 always travels in the direction in which the directional switch 23 is tilted, and the forklift 21 is moved in the direction opposite to the driver's intention as seen in the conventional forklift. You won't run. Therefore, the driver can operate the forklift as intended and perform the operation safely. Further, when the directional switch 23 is tilted, the traveling control means 2 sets the control mode of the drive wheels 24. Therefore, the control mode once set does not cause the driver to tilt the directional switch 23 again. As long as it is not changed, the operability that the traveling direction of the forklift 21 can be changed only by operating the handle 25 is not impaired.
[0032]
If the forklift is equipped with a backup battery different from the battery serving as the power source for the traveling motor 3, the control mode of the traveling motor 3 is maintained even while the traveling motor 3 is turned off. Can be stored in the memory.
[0033]
In the above embodiment, the limit switch 6 detects the protrusion 38 on the steering gear 35 that rotates integrally with the drive wheel 24 to detect the steering angle θ of the drive wheel 24. The portion where 38 is formed may be formed as a hollow penetrating vertically, and the steering angle θ may be detected using a reflection type optical sensor instead of the limit switch 6. That is, the steering angle θ of the drive wheel 24 can be detected based on whether or not the optical sensor can detect the reflected light when the light emitted from the optical sensor is reflected on the steering gear 35. Further, the detection of the steering angle θ of the drive wheel 24 is not limited to the steering gear 35, and the steering angle θ of the drive wheel 24 is indirectly detected by detecting the operation angle of the steering wheel 25 using a potentiometer or the like. Is also good.
[0034]
In the above-described embodiment, the seat-type reach-type forklift is described as an example of the forklift 21 provided on the vehicle such that the drive wheels 24 can be steered by 360 °. However, the present invention is not limited to a sitting-type reach-type forklift, and is also applicable to a stand-up type reach-type forklift and other forklifts. An operation lever provided to be tiltable in the front-rear direction may be used.
[0035]
【The invention's effect】
The driver can cause the forklift to travel in the desired direction only by selecting the desired direction with the traveling direction selection means without selecting the traveling direction in consideration of the current steering angle of the drive wheels. Further, since the forklift does not travel in the direction opposite to the traveling direction of the forklift intended by the driver, it is possible to prevent the forklift from colliding with luggage or the like by mistake, and to safely perform the work.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a traveling drive system provided in a forklift according to an embodiment of the present invention.
FIG. 2 is a partial sectional view showing a main part of the forklift according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a steering angle of the forklift according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a steering angle detecting unit according to the embodiment of the present invention.
FIG. 5 is a flowchart for determining a control mode of the traveling motor according to the embodiment of the present invention.
FIG. 6 is a perspective view of a forklift provided with drive wheels capable of steering by 360 ° as viewed from the front of the vehicle.
7 is an enlarged perspective view of the vicinity of the driver's seat of the forklift shown in FIG. 6, as viewed from the side of the vehicle.
FIG. 8 is an explanatory diagram showing a relationship between a steering angle and a rotation direction of a drive wheel and a traveling direction of a forklift.
FIG. 9 is an explanatory diagram showing a relationship between a steering angle and a rotation direction of a drive wheel and a traveling direction of a forklift.
FIG. 10 is an explanatory diagram showing a relationship between a steering angle and a rotation direction of a drive wheel and a traveling direction of a forklift.
FIG. 11 is an explanatory diagram showing a relationship between a steering angle and a rotation direction of a drive wheel and a traveling direction of a forklift.
FIG. 12 is an explanatory diagram showing a relationship between a steering angle and a rotation direction of a drive wheel and a traveling direction of a forklift.
[Explanation of symbols]
2 Travel control means 6 Limit switch (steering angle detection means)
21 Seat-type reach-type forklift 23 Directional switch (traveling direction selecting means)
24 Drive wheel 38 Projection (steering angle detecting means)

Claims (2)

In a forklift in which drive wheels are provided to be steerable by 360 °,
A driving direction selecting means operated by a driver to select a driving direction of the forklift, a steering angle detecting means for detecting a steering angle of the drive wheel, and a driving direction selected by the driving direction selecting means. A forklift comprising: a traveling control means for determining a rotation direction of the drive wheel based on the traveling direction and the steering angle and controlling the forklift to travel in the selected traveling direction. The traveling direction selection means can select either forward or backward as the traveling direction of the forklift, and the steering angle detection means sets the steering angle of the drive wheel from -180 ° to 180 ° with respect to the forward direction of the forklift. The travel control means can be detected in the range of
In the state where the steering angle detecting means detects the steering angle within ± 90 ° with respect to the forward direction of the forklift, when the forward direction is selected by the traveling direction selecting means, the rotation direction of the drive wheel is rotated forward. Direction and
In the state where the steering angle detecting means detects a steering angle within ± 90 ° with respect to the forward direction of the forklift, when reverse is selected by the traveling direction selecting means, the rotation direction of the drive wheel is reversed. age,
In the state where a steering angle of 90 ° to 180 ° or −180 ° to −90 ° with respect to the forward direction of the forklift is detected by the steering angle detecting means, and when the forward direction is selected by the traveling direction selecting means, The rotation direction of the drive wheel is a reverse rotation direction,
In the state where the steering angle detection means detects a steering angle of 90 ° to 180 ° or −180 ° to −90 ° with respect to the forward direction of the forklift, and when the reverse direction is selected by the traveling direction selection means, The forklift according to claim 1, wherein a rotation direction of the drive wheel is a forward rotation direction.

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