JPH0134933Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a steering device for a vehicle in which one shaft is a steered shaft.

[Prior Art] In a conventional rigid axle type steering device, the postures of the left and right wheels are set to maintain a constant relationship in order to safely and reliably move the vehicle straight ahead and turn. In other words, when a car turns, each wheel takes a different turning radius, but the movement around the same turning center can be rationalized by giving different turning angles to the inner and outer wheels of the front axle, which is the turning axis. In order to prevent side slips from occurring in the tires of each wheel, as shown in Figure 5, according to Atsker Mangeant's theory, the extension line A of the inner wheel axle of the front wheel and the extension line of the outer wheel axle must be B
L so that they intersect at point O on the extension line C of the rear wheel axis.
If K is the wheelbase, K is the distance between the king pins, α is the inner wheel steering angle, and β is the outer wheel steering angle, then K/L=cot β−cot α.

However, () in the case of a vehicle with a long or short wheelbase, and () in the case of a geometrical error in the steering link, the extension line of the outer wheel axle at low speeds is the intersection point O1 with the extension line of the inner wheel axle and the rear wheel axle. They do not intersect, but intersect with the extension line of the inner ring shaft at point O2 or O3. For this reason, there is a problem that the side slip angle of the outer ring is large, and the tire wears out and its durability is impaired.

On the other hand, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 55-79758 a link mechanism that allows the steering angles of the inner and outer wheels to approach the theoretical values in a link mechanism consisting of a tie rod and a tie rod arm.

Furthermore, Japanese Utility Model Application No. 50-13341 discloses a four-wheel steering mechanism that selects two types of tie rod lengths depending on the driving mode.
If only two types of tie rods are selected, only the specified numerical values can be selected for the driving mode, resulting in poor turning performance and uneven tire wear.

Furthermore, Japanese Utility Model Application Publication No. 50-13342 also discloses a known technique similar to the above, but this known technique makes it possible to change and adjust the relative posture between the wheel knuckle and the differential arm. Uneven wear will occur.

[Purpose of the invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a steering device that prevents the tires of steered wheels from being worn out due to side slips, thereby extending the life of the steering device.

[Structure of the invention] The steering device according to the invention includes a hydraulic cylinder interposed in the tie rod of the steering shaft to make the tie rod telescopic, and a steering angle detection means for detecting the steering angles of the left and right wheels. Detects the steering angle of one wheel, calculates the theoretical steering angle of the other wheel according to the steering angle using the storage means of the theoretical steering angle value map, and theoretically calculates the steering angle of the other wheel. A control unit is provided which controls the length of the tie rod to extend or contract via a hydraulic cylinder so as to be approximately equal to the desired steering angle.

[Operation and Effect of the Invention] Therefore, in the present invention, the steering angle of the other wheel is made to be approximately equal to the theoretical steering angle of one wheel, and the steering angle of the left and right wheels of the steering shaft is adjusted to the steering angle of the left and right wheels. The tie rod length can be changed to match the steering angle. Since this operation is carried out by the storage means of the steering angle theoretical value map, it is accurate, eliminates side slips at low speeds, and, as a result, eliminates uneven tire wear and extends the life of the tires.

Furthermore, since the steering angles of the left and right wheels are appropriate, a steering device with good turning performance can be obtained.

[Examples] Examples of the present invention will be described below with reference to the drawings.

In FIG. 1, tie rod arms 4L and 4R are connected by a tie rod 5, rotating around king pins 2L and 2R of a front axle 1, which is a steering shaft, and linked to a left wheel 3L and a right wheel 3R. These tie rod arms 4L, 4R and tie rod 5
A link mechanism is formed, and the left and right wheels 3L, 3R are steered by a steering arm 6 connected to the right tie rod arm 4R.

A hydraulic cylinder 7 is interposed in the middle of the tie rod 5. That is, the tie rod 5 is divided into a left rod 5L and a right rod 5R, the left rod 5L being connected to the main body 8 of the hydraulic cylinder 7, and the right rod 5R being connected to the piston 9. The left working chamber 10a and the right working chamber 10 of this hydraulic cylinder 7
b is connected to 4 by piping 12a and 12b via pilot check valves 11a and 11b, respectively.
It is connected to a three-position electromagnetic switching valve 13, and by operating the switching valve 13, it can be selectively connected to a tank 14 or an oil pump 16 driven by an engine 15. Note that the oil pump 16 may also be used for power steering. Each of the pilot check valves 11a and 11b opens when pilot pressure acts on its pilot pressure introduction pipes 17a and 17b, and communicates the working chambers 10a and 10b with the tank 14 via the electromagnetic switching valve 13. . and,
Electromagnetic solenoids 18a and 1 of electromagnetic switching valve 13
8b is connected to a control unit 22, which will be described later.

On the other hand, a left wheel steering angle sensor 19a and a right wheel steering angle sensor 19b, which are steering angle detection means for detecting the steering angles of the left and right wheels, are attached to the left and right kingpin parts, and these sensors 19a and 19b are connected to the control unit 22. It is connected to the.

In FIG. 2, a control unit 22 is provided with a central processing unit (CPU) 23, and each of the sensors 19a, 1
9b, 20 and 21 and electromagnetic solenoid 18a,
18b. Therefore, detection signals from these sensors are input to the central processing unit 23 via the input/output device 24, and signals from the central processing unit 23 are transmitted to the electromagnetic solenoids 18a, 18b via the input/output device 24. It's getting old.
In addition to the central processing section 23, the control unit 22 is also provided with a ROM 25, ie, storage means, for storing a map of theoretical turning angle values (.theta.R to .theta.LL) shown in FIG.

Next, the operation of the present invention will be explained mainly with reference to FIG.

For example, when steering to the right, the control unit 22 inputs the steering axis θR of the right wheel from the right wheel steering angle sensor 19b (step S ₁ ), and uses the map (fourth
Read the left wheel theoretical steering angle θLL corresponding to (Fig.) (step _S2 ). Next, the steering angle θL of the left wheel is input from the left steering angle sensor 18a (step S ₃ ), and the central processing unit 23 determines whether θL>θLL−δ (step S ₄ ). Here, -δ is a negative tolerance.
In the case of θL<θLL−δ (in the case of NO in step _S4 )
In this case, the central processing unit 23 outputs an activation signal to the left electromagnetic solenoid 18a to switch the electromagnetic switching valve 13 to the parallel position, and transfers the pressure oil of the oil pump 16 to the left working chamber 10.
a, slightly extend the tie rod 5 to slightly increase θL (step _S5 ), and return to step _S3 . θL>
In the case of θLL−δ (in the case of YES in step _S3 ),
It is determined whether θL<θLL+δ (step S ₆ ). Here, +δ is a plus tolerance. θL＞θLL+δ
In this case (NO in step _S6 ), the central processing unit 23 outputs an activation signal to the right electromagnetic solenoid 18b, switches the electromagnetic switching valve 13 to the cross position, and transfers the pressure oil of the oil pump 16 to the right working chamber 10b. The tie rod 5 is slightly contracted to slightly reduce θL (step
_S7 ), return to step _S3 . Step S ₄ like this
By repeating step _S6 , θLL−δ<θL<θLL+δ, the left wheel steering angle θL is kept within the range of tolerance ±δ of the left wheel theoretical steering angle θLL, and therefore the side slip of the tire is reduced. This reduces wear and tear, resulting in longer tire life.

[Summary] As explained above, according to the present invention, a hydraulic cylinder is interposed in the tie rod of the steered shaft to make the tie rod extendable and retractable, and a steered angle detection means for detecting the steered angles of the left and right wheels is provided. The steering angle of one wheel is detected, the theoretical steering angle of the other wheel corresponding to the detected steering angle is calculated by the storage means of the steering angle theory direct map, and the steering angle of the other wheel is calculated. A control unit is installed that expands and contracts the length of the tie rod via a hydraulic cylinder so that the steering angle is approximately equal to the theoretical steering angle, which eliminates side slip of the tires on the steered wheels and extends the life of the tires. .

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention;
Figure 2 is a block diagram of the control unit, Figure 3 is a control flowchart, Figure 4 is a theoretical steering angle map,
FIG. 5 is an explanatory diagram of the Atskermangeant theory. 5...Tie rod, 7...Hydraulic cylinder, 19
a, 19b... Rudder angle sensor, 22... Control unit.

Claims (1)

[Scope of utility model registration request] A hydraulic cylinder is installed in the tie rod of the steered shaft to make the tie rod extendable and retractable, and a steered angle detection means is provided to detect the steered angle of the left and right wheels. The theoretical steering angle of the other wheel corresponding to the steering angle is calculated by the storage means for the theoretical steering angle value map, and the hydraulic pressure is adjusted so that the steering angle of the other wheel becomes approximately equal to the theoretical steering angle. A steering device comprising a control unit that controls expansion and contraction of the length of a tie rod via a cylinder.