JPH049707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a steering device for an automobile,
More specifically, the present invention relates to a steering system for an automobile in which a shock absorber is provided between a vehicle body and a steering system.

(Prior Art) Some automobile steering devices are equipped with a shock absorber between the vehicle body and the steering system in order to improve high-speed straight running performance or to suppress abnormal vibrations such as shimmy and jerking back. Among these automobile steering devices, there is a
As shown in Japanese Patent No. 57311, there is a shock absorber with variable damping force, and this damping force is controlled according to the vehicle speed.

According to the automobile steering device of JP-A No. 57-57311, it is possible to obtain desirable steering characteristics and steering operation feeling depending on the vehicle speed, but the control factor in controlling the damping force of the shock absorber is the vehicle speed. Since only one of the following methods is used, it is not possible to achieve completely satisfactory control.

(Objective of the Invention) Therefore, an object of the present invention is to provide a steering device for an automobile that can provide more desirable steering characteristics and steering feel.

(Structure of the Invention) In order to achieve this object, the steering device for an automobile of the present invention includes a damping force variable shock absorber provided between the vehicle body and the steering system, and a damping force that adjusts the damping force of the shock absorber. an adjusting means, a vehicle speed detecting means for detecting the running speed of the vehicle, a steering amount detecting means for detecting the steering amount of the steering system, and the vehicle speed and the steering amount detected by both the detecting means are determined to be the same as the vehicle speed and the steering amount. In the map showing the relationship between The damping force adjusting means is further provided with a control means for controlling the damping force adjusting means to reduce the damping force of the shock absorber and increase the damping force of the shock absorber when the vehicle speed is on the high speed side.

(Embodiment) A four-wheel steering system for a vehicle according to a preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, the steering wheel 1 is suspended by a strut-type suspension, and the base end of the lower arm 2 is pivotally supported by the vehicle body 3, while the tip of the lower arm 2 is supported by the vehicle body 3. , a knuckle arm 4 coupled to the steering wheel 1 is rotatably connected. While the cylinder 5a of the shock absorber 5 is connected to the knuckle arm 4,
A piston rod 5b of the shock absorber 5 is connected to the vehicle body 3. A coil spring 6 is interposed between the cylinder 5a and the piston rod 5b, that is, the vehicle body 3, and biases the shock absorber 5 in the direction of extension.

One end of a tie rod 7A is connected to the knuckle arm 4, and the other end of the tie rod 7A is connected to a relay rod 8. Of course, this relay rod 8 is also connected to the other steering wheel (not shown) via the tie rod 7B with the same structure as the steering wheel 1, and this relay rod 8 is connected to the steering gear box 9,
It is linked to a handle (not shown) via a steering shaft 10.

A shock absorber 11 is installed between the relay rod 8 and the vehicle body 3, and the shock absorber 11 is aligned with its axis so that the direction of displacement of the tie rod 8 and the direction of generation of the shock absorbing force of the shock absorber 11 coincide as much as possible. is tie rod 8
It is arranged so that it is almost parallel to the This shock absorber 11 is of a variable damping force type, and an example thereof will be explained below with reference to FIGS. 3 and 4.

The shock absorber 11 has a cylinder 12 having an inner/outer double structure consisting of an inner cylinder 13 and an outer cylinder 14.
The inside of the inner cylinder 13 is divided into two oil chambers A and B filled with oil by a piston 15 that is slidably inserted into the inside of the inner cylinder 13. A piston rod 16 integrated with the piston 15 extends out of the cylinder 12 through a rod guide 17 in a slidable manner. It is fixed to the vehicle body 3 using 20. In addition, 53 in FIG. 3 indicates the piston rod 16.
It is a protective tube attached to the

A rubber tube 21 is disposed inside the outer cylinder 14 so as to surround the inner cylinder 13.
Inside 1 is a gas chamber C filled with pressurized gas. Of course, the outer cylinder 14 is provided with a reservoir chamber D filled with oil, and the oil chamber A and the reservoir chamber D are communicated via a valve mechanism 22 disposed at the inner bottom of the inner cylinder 13. .

The piston 15 is provided with an oil passage hole 23 that communicates the oil chambers A and B, and disc valves 24 and 2 are located on the opening sides of the oil passage hole 23.
5 are arranged. Also, the piston rod 1
6 is formed with a bypass oil passage 26 that bypasses the oil passage hole 23 and communicates the oil chambers A and B,
The bypass oil passage 26 is opened and closed by a valve body 27 rotatably disposed inside the bypass oil passage 26.

A communication hole 28 is formed in the valve body 27, as shown in FIG. When they match, the bypass oil passage 26 opens and the oil chambers A and B communicate with each other, and the valve body 28 rotates, for example, 90 degrees from the position shown in FIG. When the portions 26a no longer match, the bypass oil passage 26 is closed and communication between the oil chambers A and B is cut off.

Therefore, when the bypass oil passage 26 is closed, the oil passage 26 is closed during both the extension process and the contraction process.
3, and when the bypass oil passage 26 is open, not only the oil passage 23 but also the bypass oil passage 26 are used in the extension and contraction processes. Because the oil passes through it, the damping force is small. One end of a control rod 29 rotatably fitted into the piston rod 16 is integrated with the valve body 27, and by rotating the control rod 29 from the outside, the bypass oil passage 26 is opened and closed. It is becoming more and more like this.

Note that the inner chamber 1 due to the displacement of the piston rod 16
Changes in volume within the gas chamber 3 are compensated for by the oil flowing back and forth between the reservoir chamber D and the oil chamber A, and cavitation is prevented by the pressurizing action of the gas chamber C.

As described above, such a shock absorber 11 is fixed to the vehicle body 3 at the tip of its piston rod 16, and the cylinder 12 is connected to a rubber bush 31, a bearing member 32, etc. via a connecting rod 30 fixed thereto. The relay rod 8 is connected to a connecting shaft portion 33 (see FIG. 1) that projects from the relay rod 8.

The control rod 29 or valve body 27
is adapted to be rotated by a motor 34 serving as a damping force adjusting means. Therefore, the case 35 of the motor 34 is fixed to the bracket 19 with screws 36, and the output shaft 37 of the motor 34 is fixed to the engagement part 38 formed at the tip thereof.
are engaged with the distal end of the control rod 29 so as to rotate integrally with each other.

As shown in FIG. 5, the motor 34 is at a position where the bypass oil passage 26 is opened by operation of a drive circuit 34a in response to a switching command signal from a control unit 39 as a control means;
It is designed to have two positions: a closed position and a closed position.

In order to perform the above-described control, the control unit 39 stores a damping force switching line L _C of the buffer 11 as shown in FIG.
This switching line L _C is predetermined from the steering angle θ and the vehicle speed V based on the formula a=K ₁ V ⁿ⁻ K ₂ θ ^m . In the above formula, a indicates a predetermined value for the above switching, K ₁ , K ₂ , n, and m are constants, and K ₁ and K ₂ are values for determining the rising position of the above line _LC . In addition, n and m are used to weight V and θ, and by appropriately selecting n and m, the curvature of the line L _C can be changed. Note that the dashed line in FIG. 6 indicates the area of use.

Connected to the control unit 39 are a vehicle speed sensor 60 that detects the vehicle speed V and generates a vehicle speed signal S _V , and a steering angle sensor 61 that detects the steering angle θ and generates a steering angle signal S. The control unit 39 receives the vehicle speed signal S _V and the steering angle signal S〓, applies these signals S _V , S〓 to the switching line _LC , and determines the signal S V , S〓 determined by the above-mentioned signals S _V , S〓. When the coordinates are on the higher vehicle speed side than the switching line L _C , the drive signal S D is applied to switch the damping force of the shock absorber 11 in the direction of increasing it, and when the coordinates are on the lower vehicle speed side than the line L _C , the drive signal S _D is applied. The return signal S _R for switching in the direction of decreasing the damping force is
Each signal is output to the drive circuit 34a.

Next, the specific configuration of the drive circuit 34a will be explained with reference to FIG.

The motor 34 has a pair of sliders 41 and 42 that rotate integrally with the rotor 40 thereof. The pair of sliders 41 and 42 are each shaped like an arc, and one slider 41 is always in contact with the fixed contact 43, and the other slider 42 is in contact with the two fixed contacts 44, 45, it comes into contact with one of them at the end of its stroke, and with both of them at an intermediate stroke position. The fixed contact 43 is connected to a battery 47 via a switching relay 46, and when the coil 46a of the switching relay 46 is energized, the fixed contact 43 is switched to the contact 46b side as shown in the figure. 43 is connected to the positive terminal of the battery 47. Further, when the coil 46a is demagnetized, it is switched to the contact 46c side, and the fixed contact 43
is connected to the negative terminal of the battery 47.

On the other hand, the fixed contact 44 is connected to the battery 47 through a backflow prevention diode 48 and a switching relay 49, and the fixed contact 45 is connected to a battery 47 through a backflow prevention diode 50 and the switching relay 49. The backflow prevention diodes 48 and 50 are connected in parallel to the switching relay 49, and the directions in which the current is allowed to flow are opposite to each other.

The switching relay 49 is switched to the contact 49b side when the coil 49a is excited, and both fixed contacts 44 and 45 are connected to the backflow prevention diode 4.
It is connected to the negative side terminal of the battery 47 via 8 or 50. In addition, the coil 49a
When it is demagnetized, it is switched to the contact 49c side, and both fixed contacts 44 and 45 are connected to the positive terminal of the battery 47 via the backflow prevention diode 48 or 50.

In addition, the coil 4 of the first half switching relay 46, 49
Excitation and demagnetization of coils 6a and 49a are controlled by a control unit 39, and both coils 46a and 49a are both excited or demagnetized.

When the sliders 41 and 42 are in the position shown by the solid line in the figure, which is one of the stroke ends, the motor 34 generates a so-called hard (damping force) in which, for example, the bypass oil passage 26 of the shock absorber 11 is closed. On the other hand, when the bypass oil passage 26 is at the other stroke end, which is the position shown by the dashed line in the figure, the bypass oil passage 26 is opened (so-called soft damping force).
becomes. Assuming that the sliders 41 and 42 are now in positions corresponding to the software indicated by the dashed lines in the figure, the coils 46a and 4 of the switching relays 46 and 49 are
If 9a is excited and switched to the contacts 46b and 49b, the current from the battery 47 will flow through the contact 46b of the relay 46, the slider 41, and the fixed contact 4.
3. Motor 34 (coil), slider 42, fixed contact 45, backflow prevention diode 50, relay 4
9 through the contact 49b of the battery 47, and so on, the motor 34
Therefore, the sliders 41 and 42 rotate clockwise in the figure. As the rotation of the sliders 41 and 42 progresses, when the slider 42 comes into contact with only the fixed contact 44, the current supply to the motor 34 is stopped by the action of the backflow prevention diode 48. The motor 34 is stopped. Of course, at this time, the bypass oil passage 26 is switched from open to closed, and the buffer 11 is switched from soft to hard.

Also, from the above hardware state, the coil 46a,
When 49a is demagnetized, the relay 46 is connected to contact 4.
6c side, and the relay 49 is switched to the contact 49c side, so the current flows from the battery 47.
Contact 49c of relay 49, backflow prevention diode 48, fixed contact 44, slider 42, motor 34,
Slider 41, fixed contact 43, contact 4 of relay 46
6c, the negative terminal of the battery 47,
Since the flow is as follows, the motor 34 and therefore the sliders 41 and 42 rotate counterclockwise in the figure.
As the rotation of the sliders 41 and 42 progresses, when the slider 42 comes into contact with only the fixed contact 45, the current supply to the motor 34 is stopped by the action of the backflow prevention diode 50.
This causes the motor 34 to stop. Of course, at this time, the bypass oil passage 26 is switched from closed to open, and the shock absorber 11 is switched from hard to soft.

In the above configuration, the control unit 3
9 connects the input signals S _V and S to the above switching line L _C
Accordingly, when it is determined that the damping force of the buffer 11 should be increased, the drive signal S _D is output, that is, power is supplied, and on the other hand, when it is determined that the damping force should be decreased, the return signal S is output. _R , that is, the supply of the electric power is stopped, and the shock absorber 1 is placed in a desired state according to the traveling speed and steering speed of the automobile.
The damping force in step 1 is automatically switched.

The control unit 39 may be an electrical circuit as shown in FIG. 7 or 8.

Control unit 39 shown in FIG.
is equipped with a memory circuit 70 that stores the switching line _LC . This memory circuit 70 is stored in the vehicle speed sensor 60, and this sensor 60
receives a vehicle speed signal S _V from the vehicle speed signal S V, illuminates the vehicle speed signal S _V against the switching line L _C , and determines the steering speed at which the damping force of the shock absorber 11 should be switched when the vehicle speed is at the value indicated by the vehicle speed signal S _V. A reference steering angle signal θ ₀ is output. The output terminal of the storage circuit 70 is stored in one input terminal of a comparator 71. The other input end of the comparator 71 is connected to the steering angle sensor 61 .

The comparison circuit 71 receives the reference steering angle signal θ ₀ from the storage circuit 70 and the steering angle signal θ from the steering angle sensor 61, and outputs the drive signal S _D when the signal θ is larger than the signal θ ₀ . It's getting old.
In FIG. 7, an OR circuit 72 and a one-shot multivibrator 73 are for outputting a signal that continues to harden the buffer 11 until the next θ<θ ₀ when the drive signal S _D is generated. be.

Control unit 39 shown in FIG.
are the first and second sample and hold circuits 80,
81, the first sample and hold circuit 8
The steering angle sensor 61 and the vehicle speed sensor 60 are connected to the second sample hold circuit 81 and the second sample hold circuit 81, respectively. The first and second sample and hold circuits 80 and 81 are connected to a sampling pulse generator 82.
It holds and outputs the steering speed signal S and the vehicle speed signal _S when it receives a sampling pulse from. An arithmetic circuit 83 is connected to the output terminals of the sample and hold circuits 80 and 81, and this arithmetic circuit 83
calculates the value a of the above formula (K ₁ V ^n- K ₂ θ _n ) based on the steering angle θ and vehicle speed indicated by the signals S〓 and S _V , and outputs the signal Sa indicating this value a. .

A comparator 84 is connected at one input end to the output end of the arithmetic circuit 83, and the other input end of the comparator 84 is connected to the buffer 11.
A reference voltage generator 85 is connected to generate a reference voltage Vref for switching the damping force. This comparator 84 outputs a drive signal S _D to hard switch the damping force of the buffer 11 when the signal Sa from the arithmetic circuit 83 is higher than the voltage Vref.

Note that the shock absorber 11 performs a buffering action by increasing the speed of the piston 15 of the shock absorber 11 because the frequency of vibrations from the road surface during driving is high.
This prevents vibrations from the road surface from being transmitted to the steering wheel. On the other hand, when the handle is operated, the speed of the piston 15 is sufficiently low, so the shock absorber 11 does not interfere with the handle operation.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

In addition to the motor 34, an appropriate damping force adjustment means such as a solenoid can be used.

The buffer 11 may be of any suitable type, such as a monotube type.

The damping force is not limited to two levels, hard and soft, but can be varied to three or more levels by using a plurality of switching lines.

The shock absorber 11 can be installed between the vehicle body 3 and a suitable member of the steering system, such as between the vehicle body 3 and the tie rod 7A or 7B.

(Effects of the Invention) As explained above, the automobile steering device of the present invention controls the damping force of the shock absorber provided between the vehicle body and the steering system using vehicle speed and steering speed as control factors. Therefore, the damping force can be controlled with high precision.

Moreover, if the switching line explained in the above embodiment can be used mainly in the medium speed range of the vehicle, the switching line can be used efficiently.

Furthermore, according to the present invention, at low speeds, the damping force is changed from large to small with a small steering amount, and the steering force is reduced in most of the steering amount range to enable tight turning.
At high speeds, the damping force does not change from large to small even when the steering amount is large, preventing the steering wheel from wobbling in most of the steering amount range, and improving vehicle stability at high speeds. In addition, in the low to medium speed range, the damping force of the shock absorber is increased in the small steering angle region to prevent the steering wheel from wobbling, and the damping force of the shock absorber is reduced in the large steering angle region to eliminate the feeling of friction. I can do it.

[Brief explanation of drawings]

Fig. 1 is a front view showing an embodiment of the present invention, Fig. 2 is a plan view of Fig. 2, Fig. 3 is a sectional view showing an example of a shock absorber with variable damping force, and Fig. 4. is the third
5 is a circuit diagram showing an embodiment of the present invention; FIG. 6 is a graph showing an example of a switching line used to control the damping force of the shock absorber; FIG. Figure 8 is a circuit diagram showing an example of a case where the control unit is configured with an electric circuit.
FIG. 7 is a circuit diagram showing another example in which the control unit is configured with an electric circuit. 1...Steering wheel, 4...Natsukuru arm, 7
A, 7B...Tie rod, 8...Relay rod,
11...Buffer, 15...Piston, 16...Piston rod, 23...Oil hole, 24, 25...
Disc valve, 26...Bypass oil passage, 27
... Valve body, 28 ... Communication hole, 29 ... Control rod, 34 ... Motor, 39 ... Control unit, 60 ... Vehicle speed sensor, 61 ... Steering angle sensor.

Claims (1)

[Claims] 1. A damping force variable shock absorber provided between the vehicle body and the steering system, a damping force adjusting means for adjusting the damping force of the shock absorber, a vehicle speed detecting means for detecting the traveling speed of the vehicle, and a steering amount of the steering system. and a steering amount detecting means for detecting the amount of steering, and when the vehicle speed and the steering amount detected by both the detecting means are equal to or higher than a predetermined vehicle speed in a map representing the relationship between the vehicle speed and the steering amount, the steering is performed as the vehicle speed increases. When the vehicle speed is on the low vehicle speed side of the two regions bisected by the boundary set in the direction where the amount increases, the damping force of the buffer is reduced, and when the vehicle speed is on the high vehicle speed side, the damping force of the buffer is reduced. A steering device for an automobile, comprising a control means for controlling the damping force adjusting means to increase the force.