JPH0531018Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a steering device for a vehicle that steers four wheels.

2. Description of the Related Art In recent years, four-wheel steering vehicles have been put into practical use, in which the rear wheels are steered when the front wheels are steered. For example, as shown in FIG. 5, the operation of the steering shaft 1 is linked to the pitman arm 2 via a steering gear, and the movement of the pitman arm 2 is transferred to a drag link 4 that connects the pitman arm 2 and the front shaft knuckle arm 3. Therefore, the signal is transmitted to the front wheel knuckle arm 3, which steers one front wheel 5A and also steers the other front wheel 5B via the tie rod 6A. The front axle knuckle arm 3 and the rear axle knuckle arm 7 are connected by two link rods 9A and 9B via a direction changing link mechanism 8 which is located in the middle and interlocks in mutually opposite directions.
In response to the movement, the rear wheel knuckle arm 7 is interlocked in the opposite direction to simultaneously steer the rear wheels 10A, 10B in a phase different from the steered direction of the front wheels 5A, 5B. 6B is a tie rod that links the rear wheels.

Problems to be solved by the invention However, according to the above conventional configuration, the front wheels 5A,
5B and the rear wheels 10A and 10B turn to opposite phases at the same time, the turning radius of the vehicle 11 becomes smaller, but as shown in FIG. At times, the rear of the vehicle 11 bulged toward the wall 12, making it difficult to escape. In addition, the turning radius was small and dangerous when turning at high speeds.

This invention solves the above problems, and when driving in general, it can be steered with only the first wheel like a conventional two-wheel steering vehicle, and when it is desired to reduce the turning radius,
When the steering wheel is turned beyond a predetermined level, the second wheel is rotated to the opposite phase to the first wheel to obtain a small turning radius, and a wheel steering device is provided that allows the vehicle to easily escape from a situation where a wall or the like is close to the side of the vehicle. The purpose is to provide.

Means for Solving the Problems In order to solve the above problems, the present invention includes a pitman arm operated by a steering shaft, a first shaft knuckle arm for steering a pair of left and right first wheels, and a pair of left and right second wheels. A switching device is provided between the second shaft knuckle arm that steers the shaft, and this switching device has a link arm connected to the Pittman arm side, a front end connected to this link arm, and a rear end connected to the first shaft knuckle arm. A first wheel steering shaft is connected to the shaft knuckle arm side and passes through the switching device main body so as to be movable in the axial direction, and a front end portion is connected to the link arm and a rear end portion is connected to the second shaft knuckle arm side. a second wheel steering shaft that passes through the switching device main body so as to be movable in the axial direction;
The vehicle is configured to include a regulating means for regulating the movement of the wheel steering shaft, and regulating the movement of the first wheel steering shaft within a range exceeding the steering range of the first wheel, and at the same time allowing movement of the second wheel steering shaft. It is something.

Operation In the above configuration, the operation of the steering shaft within the steering range of the first wheel during general driving is linked to the first wheel steering shaft from the pitman arm via the link arm, and from this first wheel steering shaft to the first wheel steering shaft. The first wheel is steered in conjunction with the shaft knuckle arm. At this time, the movement of the second wheel steering shaft is restricted by the switching device main body by the restriction means, and the second wheel is not steered. In addition, when attempting to turn with a smaller turning radius, the steering shaft is moved to the limit of the steering range of the first wheel, and then the steering shaft is driven in the same direction.
The first wheel is fixed in position at the maximum turning angle by regulating the movement of the first wheel steering shaft by a regulating means, and
The second wheel steering shaft is moved to interlock the second shaft knuckle arm, and the second wheels are steered in a phase opposite to that of the first wheels, thereby steering the four wheels.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings. The same reference numerals are given to the same members and substantially the same members as in the conventional example, and the explanation thereof will be omitted.

In FIG. 1, a pitman arm 2 is operated by a steering shaft 1 via a steering gear, and a pair of left and right front wheels (first wheels) 5 are shown.
The front axle (first axle) knuckle arm 3 and the pair of left and right rear wheels (second wheels) 10A and 10B are operated by the tie rod 6B.
The rear shaft (second shaft) knuckle arm 7, which is synchronously steered, is interlocked and connected via a switching device 21.

As shown in FIG.
1A, the front end is connected to this branch link part 21, and the rear end is connected to the front-back axis knuckle arm 3,
It consists of a switching part 21B connected to the 7 side. That is, the main drag link 22, one end of which is connected to the Pitman arm 2, is rotatably connected to the center portion of the link arm 23 of the branch link portion 21A by a pin. Then, the switching device main body 24 of the switching section 21B
Two shaft holes 25 and 26 parallel to each other are penetrated through the shaft holes 25 and 26, and the front wheel (the first
A wheel) steering shaft 27 and a rear wheel (second wheel) steering shaft 28 are fitted inside to be movable in the axial direction, and the front end of the front wheel steering shaft 27 is rotated via a pin at one end of the link arm 23. In addition to being freely connected,
A front end portion of a rear wheel steering shaft 28 is connected to an elongated hole 23 a at the other end of the link arm 23 via a pin 29 so as to be rotatable and movable within a certain range along the longitudinal direction of the link arm 23 .

By the way, the front wheel steering shaft 27 has front wheels 5A,
A first recess 27a and a second recess 27b for regulating the front wheels are formed on the periphery with a moving distance L of the front wheel steering shaft 27, which is the steering range of 5B, and the center periphery of the rear wheel steering shaft 28 is formed. A third recess 28a for regulating the rear wheel is formed in the third recess 28a. In the center of the switching device main body 24, there is provided a stopper hole 30 for a steering shaft which communicates the respective shaft holes 25 and 26 with each other.
5 and 26, and one end is the device main body 24.
It is formed to open on the side surface on the rear steering shaft 28 side. Furthermore, the front wheel steering shaft 27 and the rear wheel steering shaft 2
The stopper hole 30 between 8 has a first recess 27a and a second recess 27b located at the upper and lower end positions
stopper balls 31a, 31b that can be fitted into the third recess 28a, and the slide shaft 3 disposed between the stopper balls 31a, 31b.
A stopper member 31 consisting of 1c is slidably installed inside. And this stopper member 31
As shown in FIG. 2, the length a is set to be longer than the distance b between the front and rear wheel steering shafts 27, 28 by the depth c of each recess 27a, 27b, 28a, and the other The end stopper ball 31b is the third
In the restricted state of the rear wheel steering shaft 28 fitted in the recess 28a, the front wheel steering shaft 27 is in the released state in which the one end side stopper ball 31b leaves the first or second recess 27a, 27b, and as shown in FIG. 3b. As shown, in the regulated state of the front wheel steering shaft 27 in which the stopper ball 31a on one end is fitted into the first or second recess 27a, 27b, the stopper ball 31a on the other end
1b separates from the third recess 28a of the rear wheel steering shaft 2
8 release state. A detent ball 32 is movably disposed within the stopper hole 31 between the opening cover 33 and the rear wheel steering shaft 28 and can be fitted into the third recess 28a.
The rear wheel steering shaft 28 is controlled by a coil spring 34 interposed between the opening cover 33 and the detent ball 32.
When the other end side stopper ball 31b is biased toward the side and fitted into the third recess 28a, the force for regulating the position of the rear wheel steering shaft 28 by the other end side stopper ball 31b is increased.

As shown in FIG. 1, the rear end portion of the front wheel steering shaft 27 is swingably connected to the front axle knuckle arm 3 via a front wheel drag link 35, and the turning portions of the front axles 5A and 5B are A front wheel stopper 37 is provided to restrict the range. Further, the rear end portion of the rear wheel steering shaft 28 is connected to first and second rear wheel drag links 36 in which the direction change link mechanism 8 is interposed.
It is swingably connected to the rear shaft knuckle arm 7 by a and 36b. In the direction change link mechanism 8, the rear end portion of the first rear wheel drag link 36a is swingably connected to one end portion of the direction change link arm 8b whose central portion is rotatably supported by a pin 8a. At the same time, the tip of the second rear wheel drag link 36b is swingably connected to the other end of the direction changing link arm 8b, thereby transmitting the movement of the rear wheel steering shaft 28 to the rear shaft knuckle arm 7 in the opposite direction.

Note that the front wheel drag link 35 and the first or second rear wheel drag link 36a, 36b
A power booster may be installed to assist the steering force (power steering).

Next, the operation of this steering device will be explained.

When traveling straight, as shown in FIG.
The movement of the rear wheel steering shaft 28 is restricted by fitting into the recess 28a. When the steering wheel is turned and the steering shaft 1 is rotated in the steering range of the front wheels 5A and 5B, the pitman arm 2 rotates via the steering gear and the main drag link 22 moves, for example, in the direction A, and the link arm 23, the front wheel steering shaft 27 connects to the switching device main body 2.
4 in direction B, and front wheel drag link 35.
The front shaft knuckle arm 3 is rotated via the front shaft knuckle arm 3 to steer the front wheels 5A and 5B.

Next, when the steering wheel is turned to the limit of the steering range of the front wheels 5A and 5B and moved to the position shown in FIG. 3a, where the first recess of the front wheel steering shaft 27 is located opposite the stopper hole 30 , the stopper member 31 is moved in the direction of arrow C on the front wheel steering shaft 27 side by the axial force applied to the rear wheel steering shaft 28, and the one end side stopper ball 31a is moved into the first recess 27.
a, restricts the movement of the front wheel steering shaft 27, and is also restricted by the front wheel stopper 37, so that the front wheel 5
The steering of A and 5B is stopped at the position shown by the imaginary line in FIG.

Furthermore, when the steering wheel is turned in the same direction, the rear wheel steering shaft 28 is moved, as shown in FIG.
The rear axle knuckle arm 7 is rotated via the rear wheel drag link 36b, and the rear wheels 10A, 10B are steered in opposite phase to the front wheels 5A, 5B as shown by the imaginary lines in FIG.

When the handle is returned from the position shown in Fig. 3b, the rear wheels 10A, 10B
After the vehicle is returned to the straight traveling state, the front wheels 5A and 5B are returned.

Also, when the handle is turned in the opposite direction, the front and rear wheels 5A, 5B, 10A,
10B are each steered in opposite directions.

In the above embodiment, the branch link section 21A of the switching device 21 may be a link device shown in FIG. 4. This is because the main drag link 22 is rotatably connected to one end of the first link arm 41.
The link arm 41 has an intermediate portion swingably connected to the tip of the front wheel steering shaft 27, and the other end connected to the rear wheel steering shaft 28 via the second link arm 42.
It is swingably connected to the tip of the Therefore, when the main drag link 22 is moved in the direction of arrow D from the straight-ahead state shown in FIG. 4a, the front wheel steering shaft 27 is moved in the direction of arrow E. And Figure 4b
When the front wheels 5A, 5B reach the movement limit of the steering range shown in , the stopper member 31 moves in the direction of arrow F to restrict the position of the front wheel steering shaft 27. Furthermore, when the main drag link 22 is moved in the D direction, the rear wheel steering shaft 28 is moved in the G direction opposite to the front wheel steering shaft 27, causing the front wheels 5A, 5B and the rear wheels 10A, 10B to be in opposite phases. steer. In this case, the turning link mechanism 8 between the rear wheel drag links 36a and 36b is eliminated.

In the above embodiment, the front wheels 5A and 5B are the wheels that are steered when traveling straight ahead, and the rear wheels 10A and 10B are the wheels that are steered afterwards, but conversely, the wheels that are steered first are the rear wheels. The wheels may be used as wheels, and the wheels that are steered thereafter may be the front wheels.

Effects of the Invention As described above, according to the present invention, a switching device is provided between the pittman arm, the first axis knuckle arm, and the second axis knuckle arm, and this switching device controls the operation of the steering shaft within the steering range of the first wheel. is interlocked with the first shaft knuckle arm via the first wheel steering shaft to steer the first wheel, restrict the movement of the second wheel steering shaft to stop the steering of the second wheel, and control the steering of the first wheel. The operation of the steering shaft exceeding the direction range is linked to the second shaft knuckle arm via the second wheel steering shaft to steer the second wheel, and the movement of the first wheel steering shaft is restricted to steer the first wheel. Since the structure is configured to stop the first wheel during general driving, the first wheel is stopped like a conventional two-wheel steering vehicle.
The wheels can be used for steering, and by turning the steering wheel more than the steering range of the first wheel, the second wheel can be steered in the opposite phase to the first wheel, making the turning radius smaller. Therefore, the turning radius does not become extremely small when traveling at high speeds, and even when approaching a wall or the like, it is possible to easily escape by steering only the first wheel.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, FIG. 1 is a schematic configuration diagram showing a steering device, FIG. 2 is a longitudinal sectional view showing a switching device, and FIGS. Figures 4a, b, and c are explanatory diagrams showing the link arms of other embodiments, respectively.
The figure is a schematic configuration diagram showing a conventional steering device, and FIG. 6 is an explanatory diagram of the operation of a conventional four-wheel steering vehicle. 1... Steering shaft, 2... Pitman arm, 3... Front wheel knuckle arm, 5A, 5
B...Front wheel, 7...Rear wheel knuckle arm, 21...
...Switching device, 23...Link arm, 24...Switching device main body, 27...Front wheel steering shaft, 28...Rear wheel steering shaft, 31...Stopper member, 41...First
Link arm, 42...Second link arm.

Claims (1)

[Scope of utility model registration request] A switching device is provided between a pittman arm operated by a steering shaft, a first shaft knuckle arm that steers a pair of left and right first wheels, and a second shaft knuckle arm that steers a pair of left and right second wheels. The device includes a link arm connected to the Pittman arm side, a front end connected to this link arm, a rear end connected to the first axis knuckle arm side, and penetrating through the switching device main body so as to be movable in the axial direction. a first wheel steering shaft; and a second wheel steering shaft, the front end of which is connected to the link arm, the rear end of which is connected to the second shaft knuckle arm, and which passes through the switching device main body so as to be movable in the axial direction. , provided in the switching device main body to allow movement of the first wheel steering shaft within the steering range of the first wheel, and at the same time restrict movement of the second wheel steering shaft, and within a range exceeding the steering range of the first wheel. A vehicle steering device comprising: a regulating means that regulates movement of a first wheel steering shaft and at the same time allows movement of a second wheel steering shaft.