JPS6150831B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a forklift truck capable of turning on the spot, and more particularly to an improvement in the direction changing mechanism of its steering wheels.

BACKGROUND TECHNOLOGY As shown in Fig. 2, one type of forklift truck is a drive wheel in which two front wheels FW are driven in both forward and reverse directions independently of each other, and two rear wheels are driven in both forward and reverse directions.
Two front wheels from a straight-ahead position with BW facing almost longitudinally.
A steering wheel that can change direction to a turning position on the spot along an arc centered on the midpoint O of a straight line connecting the grounding points of the FW is known. This forklift truck T can be turned on the spot about the midpoint O by rotating one of the front wheels FW in the forward direction and rotating the other in the reverse direction with the rear wheels BW in the on-the-spot turning attitude.

In this type of forklift truck, conventionally, as shown in FIG. By rotating the vertical axis V by 90 degrees using a steering device, the rear wheels BW are changed from a straight-ahead attitude to a turning attitude on the spot.

This type of forklift truck T has rear wheels.
Since the BW is separated from each other in the left and right direction, it is possible to turn on the spot using only one rear wheel, which has the advantage that the left and right stability of the vehicle body B when traveling straight is higher than that of a forklift truck.

Problems to be Solved by the Invention However, even in this forklift truck, which provides excellent lateral stability when traveling straight, as wheel A is rotated when turning, the wheel width of rear wheel BW becomes substantially smaller. There was a problem in that when turning on the spot, the rear wheel BW would be in the state shown by the two-dot chain line in Figure 2, and the lateral stability of the vehicle would be no different from that of a three-wheeled vehicle.

In addition, in order to enable on-the-spot turning, it is necessary to rotate the axle A at least 90 degrees left and right, so a steering system including a steering gear box, which is widely used in ordinary four-wheeled vehicles, is required. Therefore, a special steering device is required to rotate the turntable via a chain, cable, etc., and manufacturing costs can be reduced by using the same steering device as a regular four-wheel vehicle. There was also the problem that the effects could not be enjoyed.

Means for Solving the Problems In order to solve these problems, the present invention provides a forklift truck of the type described above, in which a vertical shaft is held rotatably around a vertical line in the body of the forklift truck, and A horizontally extending rear wheel is attached to the lower end of the axle at its longitudinal center, and then at both ends of the axle there are approximately nuts that hold each rear wheel rotatably about a substantially horizontal axis. The knuckle arms are mounted rotatably around a vertical axis, each of the knuckle arms extending from the knuckles is connected to the vehicle body by a tie rod, and the vertical shaft is provided with an arm extending away from its axis. , a steering device including a steering gear box is connected to the free end of the arm, and the steering wheel changes from the straight-ahead attitude to the on-spot turning attitude by rotating the arm by an angle smaller than 90 degrees by the steering device. It was designed to be changed.

Functions and Effects By doing this, the two steering wheels are located at a certain distance from each other in the left and right directions of the vehicle body even when turning on the spot, resulting in higher lateral stability compared to a three-wheeled forklift truck. can be kept.

Furthermore, by rotating the arm at an angle smaller than 90 degrees, the steering wheel can be turned by approximately 90 degrees, so the arm can be rotated by a steering device commonly used in general four-wheeled vehicles. By reducing the cost of the steering device due to the mass production effect, it is possible to reduce the cost of the forklift truck.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 6 is a schematic plan view of the forklift truck, and FIG. 5 is a diagram showing the steering device taken out. The left and right front wheels 301L and 301R of the forklift truck 300 are drive wheels driven in both forward and reverse directions by mutually independent drive devices.

The wheels (rear wheels) 11L and 11R move from a straight-ahead posture facing approximately in the front-rear direction as indicated by the broken line BW in FIG. It is possible to change direction from tsuki to turning position on the spot. And the wheels 11L,
With 11R in the on-the-spot turning position, the front wheel 301
By rotating one of L and 301R in the normal direction and rotating the other in the reverse direction, the forklift truck 300 is configured to turn on the spot around the midpoint O.

The axle mechanism 100 of this forklift truck 300 is shown in FIGS. 3 and 4. In these figures, an axle holding member 1 fixed to a vehicle body has a vertically fixed cylindrical member 1a, and this cylindrical member 1a rotatably holds a vertical shaft 3 via a bearing 2. As the bearing 2, one that can also receive a thrust load is used.

A serration portion 3a is provided at the upper end of the vertical shaft 3, and an arm 4 is fitted into the serration portion 3a and fixed with a nut 5. A yoke portion 3b is provided at the lower end of the vertical shaft 3, and this yoke portion 3b provides lateral stability for the vehicle.
An axle (rear axle) 6 having an appropriate length in consideration of front and rear space etc. is pivotally mounted at the center in the longitudinal direction by a pin 7. That is, the axle 6 is held by the axle holding member 1 so as to be rotatable about the axis of the vertical shaft 3, that is, about a vertical line. The axle 6 can also rotate around the horizontal pin 7, but this rotation angle is regulated by the contact between the flange 3c of the vertical shaft 3 and the top surface of the axle 6. .

The left and right wheels 11L,
11R is installed. The knuckle 8 in this embodiment is an L-shaped member in which a vertical shaft part 8a and a horizontal shaft part 8b are connected by a base part 8c, and a knuckle arm 9 extending obliquely upward is fixed to the base part 8c. A wheel 11 is rotatably attached to the horizontal shaft portion 8b of the knuckle 8 via a bearing 10, and the vertical shaft portion 8a is fitted into a vertical hole 6a provided at the end of the axle 6 via a pusher 12. is,
The nut 13 prevents it from coming off.
The positions of the vertical holes 6a provided at both ends of the axle 6 are determined so that the axle 6 and the wheels 11 do not interfere when the wheels are cut to the maximum angle in order to turn the vehicle body on the spot. There is.

The free end of the knuckle arm 9 extends on the front side of the vehicle body and at an angle that does not interfere with the axle 6 and the wheel 11 when the inner wheel in the vehicle turning direction is cut to the maximum angle. It is connected by a tie rod 14 to the free end of a fixed arm 15 fixed to the cylindrical member 1a. Spherical knobs 16 and 17 are fixed to the free ends of the nutcle arm 9 and the fixed arm 15, respectively, and these knobs 16 and 17 are engaged with spherical recesses provided at both ends of the tie rod 14. There is. The free end of the fixed arm 15 is spaced apart from the pivot point Q of the axle 6, that is, the axis of the vertical shaft 3, as shown in FIG. , protruding with an appropriate length and angle to allow rotation so that the cutting angle of the inner and outer wheels becomes inside>outside when the wheels 11 turn at their maximum, which is one of the conditions necessary for on-spot turning. and pivot point 17 with tie rod 14.
is located at the same position as the center point of the radius where the connection point 16 between the tie rod 14 and the knuckle arm 9 passes through all the right-turning, neutral, and left-turning positions that satisfy the above-mentioned mounting conditions of the knuckle arm 9.

Further, the free end portion of the arm 4 is connected to a steering device 200 as shown in FIG. The steering device 200 controls the rotation of the steering wheel 201 by means of a steering gear box 202.
This motion is converted into a swinging motion of the Bitmann arm 203, and this motion is transferred to the axle mechanism 100 by a drag ring 204.
It is of the type that transmits the signal to the arm 4 of the vehicle, and is commonly used in general four-wheeled vehicles.

Next, the operation will be explained.

When the steering wheel 201 is turned to the left and the drag link 204 is pulled forward (downward in FIGS. 3 and 7), the arm 4 and the vertical shaft 3 are rotated clockwise, and at the same time the axle 6 is also
As shown by the two-dot chain line in the figure, it rotates clockwise by the same angle α as the arm 4. When the axle 6 rotates by α degrees, the knuckle 8 also follows, but the knuckle 8 is rotatably supported relative to the axle 6 via the vertical shaft portion 8a, and is fixed to the base 8c of the knuckle 8. Since the free end of the knuckle arm 9 is connected to the fixed arm 15 via the tie rod 14, the knuckle arm 9 presses one end of the tie rod 14 as the knuckle 8 rotates due to the rotation of the axle 6. , the rod 14 is connected to the fixed arm 15
Rotate clockwise using the spherical knob 17 as a fulcrum.
At this time, the tie rod 14 rotates clockwise around the spherical knob 17, and the knuckle 8 rotates clockwise around the axis Q of the vertical shaft 3, and the knuckle arm 9 and tie rod 14 have different pivot points. Since the free end is connected by the spherical knob 16, the knuckle arm 9 is rotated clockwise around the vertical shaft portion 8a as the tie rod 14 is rotated by the rotation of the axle 6. The horizontal shaft portion 8b of the knuckle 8 rotates by an angle equal to the rotation angle α of the axle 6 plus the rotation angle β of the knuckle arm 9 relative to the axle 6. Therefore, the wheels 11L and 11R held by the horizontal shaft portion 8b rotate at an angle α+ larger than the rotation angle α of the axle 6 from the straight-ahead state shown by the solid line in FIG.
Forklift truck 300 is deflected by β.
turns to the left.

When the steering wheel 201 is further turned to the left so that the wheel turning angle is maximized, the inner wheel 11L in the turning direction turns about 98 degrees, and the outer wheel 11R turns about 85 degrees, as shown by the broken line in FIG. When the condition is most suitable for turning on the spot, if the front right wheel 301R is rotated forward and the front left wheel 301L is rotated in the reverse direction, the forklift truck 300 can be turned on the spot around the center point O of the front wheels 301L and 301R. It will become.

Moreover, in this state, the left and right wheels 11L, 11
Since the center point of R does not coincide with the vehicle body center line passing through the center point O of the left and right front wheels 301L and 301R, and there is a distance L in the width direction between the two centers, that is, a tread, the forklift truck 300 cannot turn. This prevents the lateral stability from deteriorating at times.

In addition, even though the wheels 11 are rotated around 90 degrees, they do not interfere with the axle 6, and the tie rod 14 does not exceed the dead center (general four-wheel vehicles whose axles do not rotate). (In this case, the wheels and axle interfere, causing the tie rod to go beyond dead center, making it impossible to rotate the wheels by more than 90 degrees relative to the straight-ahead condition.)

Further, the rotation angle of the axle axle 6 required to rotate the wheel 11 back and forth by 90 degrees, that is, the rotation angle of the arm 4, is approximately 45 degrees, and the total rotation angle for both left and right turns is approximately 90 degrees. Therefore, it can be sufficiently operated by the steering device 200 commonly used in general four-wheeled vehicles.

Furthermore, when the wheels are attached directly to the axle as in conventional axle-swivel vehicles, the operating space shown by circle C in Fig. 7 is required in order to turn on the spot. In the embodiment, the operating space is oval-shaped D with the short axis in the front-rear direction.
Therefore, the width of the required space in the front-back direction is reduced by 2. This means that the space for arranging the engine, battery, etc. can be expanded, which is highly desirable in terms of vehicle design.

When the spot turn is completed and the steering wheel 201 is turned to the right, the drag link 204
is pushed backwards (upward in FIGS. 3 and 7), the arm 4 is rotated counterclockwise, and the axle 6, knuckle 8, wheel 11, etc. are also rotated in the opposite direction to return to the initial state. Then, the forklift truck 300 moves straight. steering wheel 20
1 is further turned to the right from this state, the axle 6,
The knuckle 8, wheels 11, etc. rotate counterclockwise, and the forklift truck 300 turns clockwise.

In the above embodiment, a so-called "Lemoin style" nutacle was used, but the "Elliott style"
Alternatively, it is also possible to use the “reverse Elliott formula”,
It is also possible to add a kingpin angle and camber, or toe-in.

Furthermore, if the wheel width is small, it is also possible to fix the vertical shaft 3 and the axle 6 by welding or the like. It is also possible to use a spline, key, etc. instead of a serration to connect the vertical shaft 3 and the arm 4, or to place the tie rod 14 below the axle 6, or to connect one end of the tie rod 14 to a fixed position. The means for holding it is not limited to the fixed arm 15,
In short, a fixing member that is fixedly provided to the vehicle body is sufficient.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a conventional axle rotation type axle mechanism. FIG. 2 is an explanatory diagram showing the situation when the axle mechanism shown in FIG. 1 is attached to a forklift truck. FIG. 3 is a partially cutaway plan view showing an axle mechanism of a forklift truck according to an embodiment of the present invention, and FIG. 4 is a partially cutaway front view. FIG. 5 is a side view showing the steering device of the forklift truck.
FIG. 6 is a schematic plan view of the forklift truck. FIG. 7 is an explanatory diagram showing the operating state of the axle mechanism shown in FIGS. 3 and 4. FIG. 1: Axle holding member, 1a: Cylindrical member, 2: Bearing, 3: Vertical shaft, 4: Arm, 5: Nut,
6: Axle, 7: Pin, 8: Knuckle, 8a: Vertical shaft section, 8b: Horizontal shaft section, 8c: Base, 9: Knuckle arm, 10: Bearing, 11: Wheel, 1
2: Push, 13: Nut, 14: Tie rod, 15: Fixed arm, 6, 17: Knob.

Claims (1)

[Claims] 1 A drive wheel in which the two front wheels are driven in both forward and reverse directions independently of each other, and the two rear wheels move from a straight-ahead position facing approximately in the longitudinal direction to an arc centered on the midpoint of the straight line connecting the grounding points of the two front wheels. The steering wheel is capable of changing direction to a turning position on the spot along the same line, and when the two rear wheels are in the turning position on the spot, one of the two front wheels is rotated forward and the other is rotated in the reverse direction, so that the center point is In a forklift truck that turns on the spot around a center, the body of the forklift truck has a vertical axis rotatably held around a vertical line, and a rear axle extending horizontally is attached to the lower end of the vertical axis along its longitudinal axis. Install in the center of the direction,
Then, knuckles that hold the two rear wheels rotatably about substantially horizontal axes are attached to both ends of the axle so as to be rotatable about substantially vertical axes, and extend from the knuckles. Each knuckle arm is connected to the vehicle body by a tie rod, and the vertical shaft is provided with an arm extending away from its axis;
A steering device including a steering gear box is connected to the free end of the arm, and the steering wheel is changed from the straight-ahead attitude to the on-the-spot turning attitude by rotating the arm by an angle smaller than 90 degrees by the steering device. A forklift truck characterized in that it is oriented in the direction of the forklift truck.