JPH10310078A - Vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle in which controllability can be improved. SOLUTION: In a vehicle provided with an advance wheel having a circumferential center line is set along in the advance direction, and a steered wheel 3 steered by operation of a steering wheel H, in which a wheel base as the shortest length from a steering center point of the steered wheel 3 to a rotational axis of the advance wheel is changed, a steering rotation ratio changing means G is provided to increase/decrease a steering rotation ratio K(=θD/θH) as a ratio of a rotation angle θD of the steered wheel 3 to a rotation angle θH of the steering wheel in accordance with the wheel base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle capable of improving maneuverability even when a wheel base changes.

[0002]

2. Description of the Related Art In recent years,
2. Description of the Related Art An omnidirectional mobile cargo handling vehicle has been proposed as a vehicle, particularly a cargo handling vehicle that can freely travel in a narrow passage. As shown in FIG. 5, the cargo handling vehicle f includes left and right road wheels a and b disposed at one end of a vehicle body, and a drive wheel c disposed at the other end and steered by operating a steering wheel. The left and right load holes a and b are configured to be steerable. The specific configuration of such a cargo handling vehicle f is described in detail in, for example, JP-A-5-116463, JP-A-5-178232, JP-A-5-201349, and JP-A-5-246347. Have been.

In such a cargo handling vehicle f, for example, as shown in FIG. 5, the center lines in the circumferential direction of the left and right road wheels a and b are fixed along the traveling direction A parallel to the vehicle body center line CL. In the normal driving mode in which the vehicle runs by steering only the drive wheel c, or as shown in FIG. 6, the right road wheel b is fixed along the traveling direction B orthogonal to the vehicle body center line CL. c, and the left road wheel a is steered such that the rotation axis of the left road wheel a intersects the intersection of the rotation axis of the drive wheel c and the rotation axis e of the right load wheel b. The vehicle can be driven by selecting a lateral traveling mode or the like, such as traveling with the vehicle, depending on the situation.

[0004] By the way, the wheel base of the vehicle is generally determined from the steering center point d of the drive wheel c which is the steered wheel.
It is defined as the shortest length of the road wheel a (or b) which is a traveling wheel along the traveling direction up to the rotation axis e. In the traveling mode of FIG. 6, the wheel base is shorter than the traveling mode of FIG. (L1> L2).

As described above, in the cargo handling vehicle f, although the wheel base changes depending on the traveling mode, the steering wheel g
The drive wheel d (shown in FIG. 5) is mechanically linked to the drive wheel d, and its rotation ratio is usually always constant. Therefore, depending on the traveling mode, the turning radius of the vehicle body is different even if the rotation angle of the steering wheel is the same, so that there has been a problem that a sense of incongruity arises in maneuverability, driving feeling and the like. In particular, in a traveling mode in which the wheelbase is short, the turning radius of the vehicle body is smaller than when the wheelbase is long.

The present invention has been devised in view of the above-mentioned problems, and in a vehicle having a variable wheelbase including a cargo-handling vehicle as described above, the rotation angle θ _H of the steering wheel is changed.
Rotation ratio K, which is the ratio of the rotation angle θ _D of the steered wheels corresponding to
It is an object of the present invention to provide a vehicle capable of improving the maneuverability based on providing a steering rotation ratio changing means for increasing / decreasing (= θ _D / θ _H ) according to a wheel base.

[0007]

According to the first aspect of the present invention, there is provided a traveling wheel having a circumferential center line extending in a traveling direction,
A vehicle having a steered wheel that is steered by operating a steering wheel, and having a wheelbase L that is the shortest length from the steering center point of the steered wheel to the rotation axis of the traveling wheel, wherein the rotation angle of the steering wheel is changed. a steering rotation ratio changing means for increasing / decreasing a steering rotation ratio K (= θ _D / θ _H ), which is a ratio of the rotation angle θ _D of the steered wheels corresponding to θ _H , in accordance with the wheel base L. I do.

The invention according to claim 2 is the vehicle according to claim 1, wherein the steering rotation ratio changing means reduces the steering rotation ratio K when the wheelbase is shortened.

Further, the invention according to claim 3 is characterized in that the steering rotation ratio changing means is a mechanical transmission for mechanically changing the speed of the steering wheel and transmitting the speed to the steered wheels. A vehicle according to claim 1 or 2.

Further, in the invention according to claim 4, the steering rotation ratio changing means includes a steering wheel operation detecting means for detecting an operating state of a steering wheel, a wheel base state detecting means for detecting a wheel base state, A rotation angle calculation unit that receives a signal from the steering wheel operation detection unit and the wheel base state detection unit to determine a rotation angle of the steered wheel; and an actuator that receives the signal of the rotation angle calculation unit and steers the steered wheel. 3. The vehicle according to claim 1, wherein the vehicle includes:

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking as an example a case where a vehicle is a cargo-handling vehicle and is a reach-type forklift equipped with a fork F as shown in FIG. . In FIG. 1, a vehicle 1 includes a drive wheel 3 that is a steerable wheel that is rotatably driven by a prime mover and that can be steered, and left and right road wheels 4 and 5 that are driven and run while bearing a load.

The drive wheel 3 is supported by a turning gear case 6A rotatably supported by the vehicle body 2. The turning gear case 6A is rotated by operating the handle H. Thereby, the drive wheel 3 can turn around the steering center point D, and can function as a steering wheel. Further, the left or right road wheels 4, 5 function as traveling wheels along the circumferential center lines SL, SR in the traveling direction, and in this example, the circumferential center lines SL, SL in the traveling direction parallel to the vehicle body center line. This shows a state along the SR.

In the present embodiment, the drive wheel 3 is linked to an electric motor which is driven by a battery as a prime mover. The rotational driving force of the drive wheel 3 can be adjusted by operating an accelerator device AC provided in a driver's seat.

The left and right road wheels 4 and 5 are supported by revolving gear cases 6B and 6C, respectively, and these revolving gear cases 6B and 6C are linked to a servo motor 9 via a conductive member 7 such as a belt. doing.
Therefore, the left and right road wheels 4 and 5 can be individually turned by driving the servo motor 9 and can maintain their positions. Each of the turning gear cases 6
A, 6B, 6C have potentiometers 10A, 10B, which can detect the steering angles of the wheels 3, 4, 5 respectively.
By attaching 10C, the present steering angle can always be detected.

In such a vehicle 1, for example, as shown in FIG. 5, the left and right road wheels 4, 5 are fixed along a traveling direction A parallel to the vehicle body center line CL which is the width direction center line of the vehicle body 2. Then, the right road wheel 5 is fixed along the traveling direction B orthogonal to the vehicle body center line CL as shown in FIG. (The left road wheel may be fixed in the traveling direction B) and the drive wheel 3
Can be switched by a mode switching device M provided in the driver's seat. The mode switching device M controls the wheel base signals L1, L2,... Of the mode selected by the steering rotation ratio changing means G described later.
Can be output.

As described above, in the vehicle 1, the wheelbase L which is the shortest length from the steering center point D of the drive wheel 3 to the rotation axis e of the road wheel 3 or 4 changes by switching the driving mode. It will be. If the wheelbase changes, it is not always necessary to provide the traveling mode as described above.

As shown in FIG. 2, the vehicle 1 has a drive wheel 3 corresponding to the rotation angle θ _H of the steering wheel H.
Steering rotation ratio K (= θ _D / θ _H ), which is the ratio of the rotation angle θ _D of
Is changed in accordance with the wheel base.

In this embodiment, the steering rotation ratio changing means G
Exemplifies a mechanical transmission device interposed between an input shaft 12 for transmitting the rotation of the handle H and an output shaft 13 having a gear 15 meshing with the turning gear case 6A. In, the speed is changed so that the steering rotation ratio K is reduced when the wheelbase is shortened. By performing the speed change in this manner, in the traveling mode in which the wheelbase is short, the rotation angle θ _D of the drive wheel 3 with respect to the steering angle θ _H of the steering wheel H becomes smaller than before, and it is possible to suppress a sharp turn of the vehicle body. Thus, the maneuverability of the vehicle can be improved.

As the steering rotation ratio changing means G, for example, various speed change mechanisms can be adopted. For example, as shown in FIG. 3, a V pulley 16 mounted on the input shaft 12 and a V pulley mounted on the output shaft 13 are used. V pulley 17 and both pulleys 1
6 and 17, a conductive belt 20 such as a steel belt (or a V-belt) is wound around the input shaft 12 and the output shaft 13 by changing the effective diameter of each of the pulleys 16 and 17. The shift is performed steplessly.

The V pulleys 16 and 17 are provided with pulley pieces 16.
A, 17A, and pulley pieces 16B, 17B opposed thereto
Can be increased / decreased by an actuator (not shown), so that the steering rotation ratio can be changed. Although not shown, known transmission means, for example, a friction wheel type, a conical belt type, a differential gear type, a fluid type, a transmission using a cone-shaped conical body, and the like can be appropriately used, but are more preferable. Can adopt a continuously variable transmission as in this example.

In this embodiment, the steering-rotation-ratio changing means G outputs a signal indicating the state of the wheelbase in the running mode, for example, the wheelbase signal L1 from the mode switching device M.
Which allows the steering rotation ratio K to be R
On the other hand, when the wheel base signal L2 is received by the mode switching, the steering rotation ratio K can be set to, for example, K = R × L2 / L1 (L2 <L1). As a result, the steering rotation ratio K can be reduced according to the decrease in the wheelbase, and the steerability of the vehicle is improved. In order to change the distance between the pulley pieces, an appropriate actuator is provided to constitute an automatic transmission mechanism.

FIG. 4 shows another embodiment of the present invention. In this example, the steering rotation ratio changing unit G includes a steering wheel operation detecting unit 21 that detects an operating state of the steering wheel H, a wheel base state detecting unit 22 that can detect a state of the wheel base L, and the steering wheel operation detecting unit 21. Rotation angle calculation means 23 for receiving a signal from wheel base state detection means 22 and determining the rotation angle of drive wheel 3
And an actuator 24 for receiving the signal from the rotation angle calculating means 23 and steering the drive wheel 3.

As the handle operation detecting means 21, for example, an absolute encoder or the like can be used. By engaging a gear 21A mounted on the detection shaft with a gear 12A of the input shaft 12 of the handle H, The steering state of the steering wheel H can always be detected. Further, as the wheel base state detecting means 22,
A mode switching device M provided in the driver's seat of the vehicle 1 can be used. And this mode switching device M
The wheel base signals L1, L2,... Corresponding to the driving mode selected by the driver are output to the rotation angle calculating means 23.

The rotation angle calculation means 23 determines the steering rotation ratio K based on the wheelbase signal from the wheelbase state detection means 22 in the same manner as in the above embodiment.
The rotation angle of the drive wheel 3 is determined by multiplying the signal from the steering wheel operation detecting means 21 by, for example, the steering rotation ratio K. Then, the determined rotation angle signal of the drive wheel 3 is sent to the actuator 24. Further, the actuator 24 includes control means for steering the drive wheel 3 based on a deviation between the current rotation angle of the drive wheel 3 and the determined rotation angle of the drive wheel 3 so as to eliminate the deviation.

In this manner, the steering rotation ratio changing means G
As in the case of the mechanical transmission, the steering rotation ratio K can be increased or decreased according to the wheelbase, and the steerability of the vehicle can be improved.

As shown in FIG. 7, the vehicle 1 is fixed along the circumferential center line of either the left or right road wheel 4, 5 in an arbitrary traveling direction, and the drive wheel 3 is A so-called attitude angle traveling mode in which the vehicle travels by steering may be performed. In this case, the traveling direction may be changed continuously during traveling, and at that time, the wheel base L3 also changes continuously.

In such a case, the steering rotation ratio K
May be set to be proportional to the change of the wheel base L as shown in FIG. As a result, the ratio (K / L) between the steering rotation ratio K and the wheel base L is always constant, so that there is an advantage that the same driving feeling is easily obtained even when the road wheel changes. .

[0028]

As described above, in the present invention, the steering rotation ratio, which is the ratio of the rotation angle of the drive wheel to the steering angle of the steering wheel, can be increased or decreased according to the wheelbase. Deterioration of the steering performance and driving feeling can be prevented, and in particular, the steering rotation ratio changing means can reduce the steering rotation ratio K when the wheel base is shortened, so that the drive wheel with respect to the steering angle of the steering wheel can be reduced. The rotation angle is reduced, and it is possible to suppress sudden turning of the vehicle body and the like, and it is possible to further enhance the maneuverability of the vehicle.

[Brief description of the drawings]

FIG. 1 is a plan view of a vehicle showing an example of an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of a steering transmission system.

FIG. 3 is a diagram showing an example of a steering rotation ratio changing unit.

FIG. 4 is a block diagram showing another embodiment of the steering transmission system.

FIG. 5 is a schematic plan view of a vehicle illustrating a wheel base.

FIG. 6 is a schematic plan view of a vehicle illustrating a wheel base.

FIG. 7 is a schematic plan view of a vehicle illustrating a wheel base.

FIG. 8 is a graph showing a relationship between a wheelbase and a steering rotation ratio.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle 2 Body 3 Drive wheel (steering wheel) 4 Left road wheel (traveling wheel) 5 Right road wheel (traveling wheel) G Steering rotation ratio changing means

Claims (4)

[Claims] 1. A traveling wheel having a circumferential center line along a traveling direction,
A vehicle having a steering wheel to be steered by operating a steering wheel, and having a wheelbase L that is a shortest length from a steering center point of the steering wheel to a rotation axis of the traveling wheel, wherein the rotation angle of the steering wheel is changed. Steering wheel rotation angle θ corresponding to θ _H
A vehicle comprising a steering rotation ratio changing means for increasing / decreasing a steering rotation ratio K (= θ _D / θ _H ) which is a ratio of _D according to the wheel base L. 2. The vehicle according to claim 1, wherein the steering rotation ratio changing means decreases the steering rotation ratio K when the wheelbase is shortened. 3. The vehicle according to claim 1, wherein the steering rotation ratio changing means is a mechanical transmission that mechanically changes the speed of the steering wheel and transmits the speed to the steered wheels. . 4. The steering rotation ratio changing means includes a steering wheel operation detecting means for detecting an operating state of a steering wheel, a wheel base state detecting means for detecting a wheel base state, the steering wheel operation detecting means and a wheel base state. A rotation angle calculation means for receiving a signal from the detection means to determine a rotation angle of the steered wheel, and an actuator for receiving the signal from the rotation angle calculation means and steering the steered wheel. 3. The vehicle according to 1 or 2.