JPH0429587B2 - - 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 has a large influence on the steering feeling depending on its operation state, and some kind of countermeasure is desired from this point of view as well. In other words, when the steering wheel is turned back from a state in which it is being turned in, there is a delay in the steering wheel following the steering operation (a delay in self-aligning torque following the steering wheel), resulting in a so-called steering failure in which the reaction force of the steering becomes zero. will occur.

(Object of the Invention) The present invention has been made in consideration of the above-mentioned circumstances, and provides a steering device for an automobile that allows an appropriate steering feeling to be obtained even when turning the steering wheel from turning to turning back. The purpose is to provide

(Structure of the Invention) In order to achieve the above-mentioned object, in the present invention, as shown in FIG. A damping force adjusting means is provided, and a steering state detecting means is provided for detecting whether or not the operating state of the steering is at a time of turning back from turning to turning back. A control unit serving as a control means that receives an output from the steering condition detecting means outputs a signal to the damping force adjusting means to increase the damping force when turning the steering wheel compared to when turning the steering wheel. There is.

(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 steering wheel 1 is rotatably connected to the tip of the lower arm 2. 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 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 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 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 is opened and the oil chambers A and B communicate with each other, and the valve body 27 is rotated, 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 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. 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, 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.
When the coil 46a of No. 6 is excited, it 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 step-down power supply for the control unit 39, and 52 is a sensor. This sensor 52
is a steering state detection sensor that detects whether the steering operation state is at the time of turning back, for example, detects the steering angle every predetermined unit time,
It is time to turn around depending on whether the calculation formula (θH+1)÷θH-1, which is calculated by dividing the steering angle θH+1 after the next predetermined unit time by the steering angle θH at a certain time and subtracting 1 from it, is positive or negative. It can be made to know whether or not. In other words, in Fig. 7, cutting is performed from the neutral position N to point α, cutting back from point α to point β, cutting again from point β to point γ, and cutting back again after point γ.
The above calculation formula is positive when cutting from N → α, β → γ and when switching from cutting back before and after the β point to cutting, but when cutting back from the α point → β point and after the γ point, and when turning back from the α point to the α point When cutting back from cutting back and forth and before and after the γ point,
The above calculation formula becomes negative. When the above calculation formula is negative, the control unit 39 excites the coils 46a and 49a of the switching relays 46 and 49 to harden the buffer 11, and when the above calculation formula is positive, the control unit 39 For example, the shock absorber 11 is made soft by demagnetizing the coils 46a and 49a. In this case, the shock absorber 11 becomes hard even when cut back, which is advantageous for those who do not like self-aligning torque very much.

Another method for determining whether or not the steering operation state is at the time of turning from turning to turning back is to detect the steering angular velocity every predetermined unit time, and to detect the steering angular velocity in the turning direction and the steering angular velocity in the steering direction. The steering angular speed is set as negative, and the calculation is made based on whether the calculation formula ωH×(ωH+1), which is the product of the steering angular speed ωH at a certain time and the steering angular speed ωH+1 at the next time, is positive or negative. It's okay.
In this case, the above calculation formula becomes negative at each turnaround before and after α point, before and after β point, and before and after γ point, while N → α point, α point → β point, β point → γ point, and after γ point At the time of cutting or cutting back, the above calculation formula becomes positive. Of course, control unit 3
9, when the above calculation formula becomes negative, the coils 46a, 49a of the switching relays 46, 49 are excited to harden the shock absorber 11, and when the above calculation formula becomes positive, the coils 46a, 49a are excited. 49a is demagnetized to soften the buffer 11. In this case, the shock absorber 11 remains soft during cutback, which is advantageous for those who prefer self-aligning torque.

Here, the damping force of the shock absorber 11 may be adjusted depending on a combination of the steering condition and the vehicle speed, and in this case, a vehicle speed sensor 53 is provided,
According to the outputs of the vehicle speed sensor 53 and the steering state detection sensor 52, the control unit 3
9 to adjust the magnitude of the damping force, an example of which is shown in FIG. Of course, in FIG. 8, the time of cutting back is the time of transition from cutting to cutting back. In this way, smooth steering operation can be achieved when traveling at low speeds, while straight-line performance can be ensured when traveling at high speeds. Note that the vehicle speed sensor 53 may be configured to know the vehicle speed by being associated with a speedometer, for example.

Further, the damping force of the shock absorber 11 may be adjusted based on a combination of the steering condition and the driving condition of the vehicle, that is, whether or not the vehicle is running steadily. In this case, a driving condition detection sensor 54 is provided to The magnitude of the damping force may be adjusted by the control unit 39 in accordance with the outputs from the state detection sensor 54 and the steering state detection sensor 52, an example of which is shown in FIG. Of course, in FIG. 9, the time of cutting back is the time of transition from cutting to cutting back. In this way, smooth operability during steady running can be obtained, while the steering wheel shock during acceleration or deceleration can be alleviated. Note that the running state detection sensor 54 may be a sensor that detects the engine load based on the magnitude of the throttle opening, intake negative pressure, etc., for example. Further, the sensor 54 may be configured to detect the brake load based on, for example, the amount of depression of the brake pedal, the magnitude of the brake fluid pressure, or the like. Further, the sensor 54 may be an inertia switch operated by inertia using a weight.

The data shown in FIGS. 8 and 9 described above may be programmed into the control unit 39, for example, by a microcomputer.

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.

(Effects of the Invention) As is clear from the above, the present invention has the following advantages:
By setting the steering force at an appropriate level when the steering is shifted from turning to turning back, so-called slippage in steering can be eliminated, and a favorable steering operation can be obtained.

[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 graph showing an example of a steering operation state. FIG. 8 is a graph showing an example of changing the damping force of the shock absorber depending on the steering operation state and vehicle speed. 9th
The figure is a graph showing an example of changing the damping force of the shock absorber depending on the steering operation state and the driving state of the vehicle. 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, 52...steering state detection sensor, 53...vehicle speed sensor, 54...driving state detection sensor.

Claims (1)

[Scope of Claims] 1. A variable damping force 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 a steering operation state that is changed from turning to turning back. a steering state detecting means for detecting whether or not it is time to turn back to the steering state detecting means; receiving an output of the steering state detecting means;
A steering device for an automobile, comprising: a control means for outputting a signal to the damping force adjusting means to increase the damping force during the turning operation compared to when the steering wheel is turned.