JPH0429586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering system for an automobile, which includes a shock absorber installed between a vehicle body and a steering system.

(Prior Art) Some automobile steering devices include a shock absorber installed 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. As shown in Japanese Unexamined Patent Publication No. 57-57311, some of these automobile steering devices have shock absorbers of variable damping force type, so that the damping force is increased when driving at high speeds, and the damping force is increased when driving at low speeds. There are some that reduce the force.

By the way, the steering device is a device that has a great influence on its steering feel (especially steering ability) and abnormal vibrations such as shimmy and jerking, depending not only on the speed of the vehicle but also on the quality of the road surface. From this perspective, some kind of countermeasure is desired. In other words, for example, when driving on a highly uneven area such as a passageway under construction, the bumps and bumps become abnormally large, and when driving in muddy or rainy weather, the coefficient of friction between the wheels and the road surface decreases. Even if a slight force is applied to the steering wheel, the steering will continue, resulting in a risk of unnecessarily increasing the steering angle.

(Object of the Invention) The present invention was made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a steering device for a vehicle that can perform appropriate steering depending on the road surface condition.

(Structure of the Invention) In order to achieve the above-mentioned object, in the present invention, the damping force of the shock absorber is made larger when the road surface condition is poor than when the road surface condition is good.

Specifically, as shown in Figure 1, a damping force adjusting means such as a motor is provided to adjust the magnitude of the damping force of the shock absorber, which has a variable damping force type, while also detecting the good or bad road surface condition. A road surface condition detection means is provided to detect the condition of the road. A control unit serving as a control means receiving an output from the road surface condition detecting means controls the damping force so that the damping force of the shock absorber becomes larger when the road surface condition is bad than when the road surface condition is good. It is adapted to actuate the force adjustment means.

(Example) In FIGS. 2 and 3, 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. A knuckle arm 4 coupled to the wheel 1 is rotatably connected to the tip of the lower arm 2. A cylinder 5a of a shock absorber 5 is connected to the knuckle arm 4, and 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 steering wheel on the other side (not shown) via the tie rod 7B with the same structure as the wheel 1, so this relay rod 8 is connected to the steering gear box 9 and the steering shaft. It is linked to a handle (not shown) via 10.

A shock absorber 11 is installed between the relay rod 8 and the vehicle body 3, and the shock absorber 11 is arranged so that its axis is aligned so that the direction of displacement of the relay rod 8 and the direction of generation of the shock absorbing force of the shock absorber 11 coincide as much as possible. is arranged so as to be substantially parallel to the relay rod 8. This shock absorber 11 is of a variable damping force type, and an example thereof will be explained below with reference to FIGS. 4 and 5.

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 12 is formed 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 12. 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. 4 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. .

A communication hole 23 is formed in the piston 15 to communicate the oil chambers A and B, and disc valves 24 and 2 are located on each opening side 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 27 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 stroke and the contraction stroke.
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 both the extension stroke and the contraction stroke. 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 cylinder 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. 2) 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. 6, the motor 34 operates in two positions, a position in which the bypass oil passage 26 is opened and a position in which it is closed, in response to a switching command signal from a control unit 39 serving as a control means. An example of a drive circuit for this motor 34 will be explained below with reference to FIGS. 4 and 6. The motor 34 has a rotor 40 and a pair of sliders 41 and 42 that rotate together. 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 and 45. However, at the end of the stroke, it comes into contact with one of them, and at an intermediate stroke position, it comes into contact with both of them. 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 excited, the fixed contact 43 is switched to the contact 46b side as shown in the figure, and the fixed contact 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.
Both fixed contacts 44 and 45 are connected to a negative terminal of a battery 47 via a backflow prevention diode 48 or 50. In addition, the coil 49
When a is demagnetized, it is switched to the contact 49c side, and both fixed contacts 44 and 45 are connected to the battery 47 via the backflow prevention diode 48 or 50.
Connected to the positive terminal of the

Incidentally, the coil 4 of both switching relays 46 and 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 FIG. 6, 51 is a sensor as a road surface condition detection means, 52 is a step-down power source for the control unit 39, and the sensor 51 is used to detect road surface conditions such as the degree of unevenness of the road surface and the degree to which the wheels tend to slip. , control unit 39 as control means
This is what is output to. In order to know the degree of the unevenness of the road surface, for example, it is sufficient to know the displacement between the sprung mass and the unsprung mass. For this purpose, a sensor detects the displacement amount or displacement speed between the cylinder 5a and the piston rod 5b of the shock absorber 5. 51 may be used for detection. Furthermore, in order to know the slip state of the wheels, for example, in the case of a vehicle equipped with an anti-skid system, the sensor 51 may pick up the activation signal of the anti-skid system. Alternatively, the engine rotational speed and the rotational speed of the wheels may be detected, and it may be determined whether the wheels are slipping by taking into consideration the gear ratio of the transmission at that time. Further, the road surface condition is detected by detecting the operating condition of the wiper with the sensor 51, for example, when the wiper is operating, it is a rainy day and the road surface is bad (easily slippery). You can do it like this.

The control unit 39 controls the motor 34 in accordance with the quality of the road surface detected by the sensor 51. When the road surface is in a rough state with severe unevenness or is prone to slipping, the control unit 39 controls the switching relay. Each coil 46a, 49a of 46, 49 is excited to put the buffer 11 in a hard state. On the other hand, when the road is in a good condition, such as when the road surface is flat or hard to slip, the control unit 39 demagnetizes the coils 46a and 49a to put the shock absorber 11 in a soft state.

In this way, when the road surface condition is poor, the shock absorber 11 becomes hard, so vibrations such as bumps are reliably suppressed when driving on extremely uneven roads, and when the road surface is prone to slipping, a relatively large force is applied to steering. It is possible to avoid the risk of unnecessarily large steering due to a stiff steering feeling that requires

Here, the shock absorber 1
may be made hard to ensure an appropriate amount of steering force. That is, during the above-mentioned turning back, the self-aligning torque of the tires causes so-called "missing" of the steering, and the steering reaction force becomes extremely small, which is not preferable for steering. Particularly, such a phenomenon becomes noticeable when the steering wheel is shifted from being turned in (when the steering wheel is operated in a direction to increase the steering angle) to being turned back. Therefore, if the shock absorber 11 is made hard even when the steering wheel is turned back, the above-mentioned "coming off" can be prevented and an appropriate steering feeling can be obtained.

To detect when the steering wheel is turned back as described above, for example, the steering displacement when the steering wheel is turned is set as "positive", the steering displacement when the steering wheel is turned back is set as "negative", and the steering displacement θH at a certain time and a predetermined time after this are calculated. Assuming that the steering displacement is θH+1, when the two steering displacements are multiplied together, if the result is negative, it is determined that it is time to turn back from the cut, and the shock absorber 11 may be made hard.

FIG. 7 shows an example of how the damping force of the shock absorber 11 is adjusted depending on the combination of the quality of the road surface condition and whether the steering wheel is turned in or out. be. Of course, something like the one shown in FIG. 7 may be created in advance as a map, for example, and the control unit 39 may be configured with a microcomputer or the like, and the map may be programmed into the control unit 39.

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 stages, hard and soft, but can also be variable in three or more stages or steplessly.

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.

When the control unit 39 is configured by a microcomputer, a digital type,
It can be configured by any analog type.

A timer may be built into the control unit 39 so that when it receives an output from the sensor 51 that the road surface condition is poor, it hardens the shock absorber 11 for a predetermined period of time, such as 15 seconds, from the time the output is received. . This prevents the shock absorber 11 from being frequently switched between the hard and soft modes within a single period of time, for example, when there are intermittent paths with severe unevenness.

(Effects of the Invention) As is clear from the above, the present invention has the following advantages:
As a result of automatically adjusting the magnitude of the damping force of the shock absorber depending on the quality of the road surface condition, appropriate steering can be performed according to the road surface condition.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is a front view showing an embodiment of the present invention. FIG. 3 is a plan view of FIG. 2. FIG. 4 is a sectional view showing an example of a variable damping force type shock absorber. FIG. 5 is an enlarged sectional view taken along the - line in FIG. 4.
FIG. 6 is a circuit diagram showing one embodiment of the present invention. FIG. 7 is a diagram showing an example of a case where the damping force of the shock absorber is changed depending on the steering wheel's turning or turning back and the road surface condition. 1...Steering wheel, 4...Natsukuru arm, 7A, 7
B...Tie rod, 8...Relay rod, 11...Buffer, 15...Piston, 16...Piston rod, 2
3...Oil hole, 24, 25...Disc valve, 26
...Bypass oil passage, 27...Valve body, 28...Communication hole,
29...Control rod, 34...Motor, 39
...Control unit, 51...Sensor.

Claims (1)

[Scope of Claims] 1. A damping force variable shock absorber installed between the vehicle body and the steering system; a damping force adjusting means for adjusting the damping force of the shock absorber; and detecting whether the road surface condition is good or bad. road surface condition detection means; and said damping force adjustment means that receives the output of said road surface condition detection means and adjusts said damping force of said shock absorber to be larger when said road surface is rough than when said road surface is good. A steering device for an automobile, comprising: a control means for operating; and a steering device for an automobile.