JP2669232B2 - Vehicle steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system used for steering a front wheel of an automobile.

[0002]

2. Description of the Related Art Vehicles (vehicles) are equipped with a hydraulic power steering device.

Conventionally, in such a steering device, a steering gear (for example, a rack and pinion type et) is constructed by providing a torsion bar between the input and output parts.
c. ) Is connected to a steering wheel via a steering shaft, and the steering gear is twisted by a torsion bar to supply a hydraulic pressure from an oil pump to a power cylinder to generate a necessary assist force. A structure provided with an assist system using a rotary valve is used.

[0004] Such a steering device steers the front wheels by converting the rotation of a steering wheel transmitted via a steering shaft and a torsion bar into a displacement in a steering direction by a steering gear. According to the torsion of the torsion bar (due to road surface resistance) generated during the steering, the rotary valve is rotated and displaced, and hydraulic pressure is supplied to the right or left chamber of the power cylinder to drive the front wheels in the steering direction. However, the steering force is reduced.

[0005]

By the way, it is known that the steering characteristic of an automobile has a motion characteristic called an understeer characteristic.

That is, the kinetic characteristics of an automobile are basically governed by the magnitude of the cornering power (tire lateral force generating ability) acting on the front and rear wheels. If the cornering power of the front wheels is small, the understeer characteristic (steering angle) is obtained. When the speed is kept constant, the turning radius increases), and when the cornering power of the front wheels increases, the understeer characteristics tend to weaken.

[0007] Here, if the tendency of the understeer characteristic is strong, it becomes difficult to bend in the middle to low speed range, but the vehicle becomes a stability-oriented vehicle having high stability in the high speed range. -It becomes a car that is oriented towards the tee.

Usually, it is difficult for a vehicle to achieve both the flexibility in the middle and low speed ranges and the stability in the high speed range. Therefore, it is necessary to select either stability-oriented or sporty-oriented. Are forced to do so. Generally, a weak understeer characteristic is given to the vehicle. For this reason,
I had a situation in which I could not fully utilize the driving performance of a car.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle steering device capable of greatly improving the vehicle's dynamic characteristics.

[0010]

In order to achieve the above object, a vehicle steering system of the present invention axially divides a steering shaft for transmitting a displacement of a steering wheel to a steering gear, and one of the divided ones is divided. the shaft end of the steering shaft portion is provided with a torsion bar extending toward the shaft end of the other of the steering shaft portion, the other
Extending from the coaxial end to the shaft end of the
And a guide part that is arranged parallel to the side of the torsion bar
Material is provided between the torsion bar and the guide member.
A plate that connects slidably along the axial direction of the torsion bar
It is to provide a slider in the shape of a bar and to provide an operating means for continuously operating the slider in the axial direction of the torsion bar.

[0011]

According to the vehicle steering system of the present invention, when the slider is moved by the operating means along the axial direction of the torsion bar, the point for restraining the rotation direction of the torsion bar is displaced according to the movement of the slider. I do. That is, the torsional rigidity of the torsion member forming a part of the steering shaft is continuously variable. As a result, the torsional rigidity of the torsion bar can be changed from the highest state to the lowest state.

This means that the torsion bar can be continuously changed from a state where the compliance (softness = the reciprocal of rigidity) is fully utilized to a state where it is hardly utilized. Here, it is known that in a steering device, compliance acts as a function of lowering the cornering power of the front wheels. Therefore, the understeer characteristic changes continuously from "weak" to "strong" (or oversteer characteristic; "strong" ~
"Weak" changes).

Therefore, it is possible to adjust the steering characteristic which has been unique in the past, and it is possible to give all of the understeer characteristic (or all of the oversteer characteristic) to one automobile (of the motion characteristic of the vehicle). Improvement).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention shown in FIGS.
A description will be given based on the embodiment. FIG. 2 is a diagram showing the structure of a power steering apparatus for an automobile (vehicle) to which the present invention is applied, for example, and FIG. 1 is a schematic diagram of the power steering apparatus. Numeral 1 denotes a rack and pinion type steering gear.

In the steering gear 1, a rack 3 (output section) and a pinion 4 that meshes with the rack 3 are built in a casing 2, and a shaft end section 6 (input section) of the pinion 4 is incorporated.
The first bets for the valve drive - by connecting the Shonba -5 Oh
You .

One end of the rack 3 is connected to a left front wheel 10 via a steering rod 7, a tie rod 8 (all shown only in FIG. 1), and a knuckle 9. The other end is provided via a steering rod 11, a power cylinder device 12 (a piston rod 12b penetrating through the cylinder 12a and a piston 12c provided to partition the cylinder 12a), a tie rod 13, and a knuckle 14. , Is connected to the right front wheel 10.

A handle 18 is connected to a shaft end 6 protruding from an upper end of the casing 2 via a steering joint 16 and a steering shaft 17. 17, through the first torsion bar 5, the pinion 4, the rack 3, and the steering rods 7 and 11,
The left and right front wheels 10, 10 are steered.

A rotary valve 19 (shown only in FIG. 1) having a known structure is provided between the input shaft 6 of the steering gear 1 and the end of the pinion 4 (end of the output shaft). An inflow port (not shown) of the rotary valve 19 is connected to an oil pump (not shown) driven by a traveling engine mounted on an automobile, and an outflow port is an oil reservoir (neither is shown). It is connected to the. An inlet / outlet port (not shown) of the rotary valve 19 is connected to each partitioned chamber of the power cylinder device 12. Thus, according to the displacement of the rotary valve 12, a hydraulic pressure corresponding to the steering force and the steering direction can be supplied from the rotary valve 12 to each chamber of the power cylinder device 12 (assist system).

On the other hand, as shown in FIG. 3, the steering shaft 17 is divided into a plurality, for example, two in the axial direction from the intermediate portion. Here, of the divided steering shafts 17, the upper side is a shaft portion 17a, and the lower side is a shaft portion 17b.

At one of the shaft portions 17a and 17b, for example, at the center of the shaft end of the shaft portion 17b, there is provided a second torsion bar 20 (the torsion bar of the present invention) extending toward the shaft end of the shaft portion 17a. (Corresponding to −) is integrally projected. The second torsion bar 20 has a predetermined length. On the entire outer peripheral surface of the second torsion bar-2, a large number of straight line selections 20a are formed along the axial direction.

A disk-shaped slider 25 is slidably fitted on the outer peripheral surface of the second torsion bar 20. That is, as shown in FIG. 4, the slider 25 has a through hole 25a having a concave and convex shape corresponding to the sectional shape of the second torsion bar 20 at the center. The second torsion bar
20 are slidably fitted into the selection portion.

At the end of the shaft portion 17a, a pipe 21 having a flange portion 21a at its tip is projected.
A short-length pipe portion 22 having a flange portion 22a at the tip is slidably fitted into the end of the shaft portion 17b. The pipe portion 22 is connected to a contractible bellows pipe 22b fitted in a small diameter portion on the end side of the shaft portion 17b, and is supported by the shaft portion 17b via the bellows pipe 22b. Note that the flange portion 21a and the flange portion 22a form a pair.

As shown in FIG. 4, a plurality of, for example, three guide bars 23 are provided between the opposed flange portions 21a and 22a so as to surround the second torsion bar 20.
Are distributed at equal intervals. That is, the guide bar 23
The pipes 21 and 22 are connected to each other via.

The slider-2 is attached to the guide bar-23.
5 is slidably inserted into the outer periphery of the second torsion bar 20 to guide the slider 25 along the axial direction.

As a result, the slider 25 is guided by the guide bar.
Slide along 23, the second torsion bar
The position in which the rotational direction of 20 is restricted can be changed in a wide range from the tip of the second torsion bar 20 to the root thereof. And this second toe
The rigidity of the second torsion bar 20 in the torsional direction can be varied by varying the position of regulating the torsion bar 20. The point indicated by the symbol A at the tip of the second torsion bar 20 is a point at which the compliance of the second torsion bar 20 is 100% and is utilized (compliance: 100%). The points shown are
A point where the compliance of the second torsion bar 20 is hardly utilized (compliance: 0%) is shown.

A screw shaft 26 is rotatably supported between the flange portions 21a and 22a. This screw shaft 26
Has a screw 27 on the entire outer peripheral surface sandwiched by the flange portions 21a and 22a. As shown in FIG. 4, the male screw portion is rotatably screwed into a screw portion (not shown) to be provided on the projecting piece portion 28 on the outer peripheral portion of the slider 25.

One end of the screw shaft 26 is connected to the pipe 2
1 is connected to the output shaft of a motor 29 (drive source) installed on the outer periphery of
5 is movable along the axial direction of the second torsion bar 20. Thereby, the compliance of the second torsion bar 20 can be continuously varied within the range of "0% to 100%".

Further, between the furan parts 21a and 22a,
A stroke sensor 30 is provided along the movement locus of the projecting piece 28. The protruding portion 28 is formed with a convex portion 31 serving as a detected element. And this convex part 31
Formed along the length direction of the stroke sensor 30;
The second torsion bar is inserted into the detection groove 32 as a detection unit, and is positioned from the projection 31 with respect to the groove length of the detection groove 32.
The position of the slider at 20 can be detected.

On the other hand, 33 is a control unit (only shown in FIG. 1). The control unit 33 includes, for example, a microcomputer and its peripheral circuits. The control unit 33 is connected to, for example, a dial type operation unit 34 for variably operating the compliance. This operation unit 34 is, for example, “Compliance: 100% to compliance 0”.
It consists of a dial that can be operated in the range of "%". Further, the control unit 33 includes a drive circuit 29a for the motor 29 incorporated in the steering shaft 17 and the strobe.
The sensor 30 is connected.

In the storage function of the control unit 33, for example, a map indicating the slider position in the second torsion bar 20 (range A to B) according to the compliance of the second torsion bar 20 is set. ing.

In addition, the control unit 33 includes, for example, the compliance input from the operation unit 34 and the stroke sensor 3.
A function for comparing the compliance read from the map in accordance with the output signal of 0 and a function for controlling the drive circuit 29a so that the difference of the comparison result becomes "0" are set. Predetermined position which becomes the compliance set in (the second torsion bar 20 "A ~
The slider 25 is positioned at a certain position between "B").

As a result, according to the dial operation of the operation unit 34, the second torsion bar 20 within the range of "compliance: 100% to compliance 0%".
Can be set arbitrarily (corresponding to operation means).

In the figure, 35 is an upper column cover provided so as to cover the periphery of the shaft portion 17a, and 36 is a lower column cover provided so as to cover the periphery of the shaft portion 17b. Both are fixed to the body (not shown) of the automobile.

In the steering device thus constructed, when the handle 18 is rotated, the rotation thereof causes the shaft portion 17a, the guide bar 23 and the slider-2 to rotate.
5, the second torsion bar 20, the shaft portion 17b, and the first torsion bar 5 sequentially transmit the pinion 4 to drive the rack 3 in the direction steered by the steering wheel 18.

At this time, the first torsion bar 5 is twisted by the road surface resistance. According to this twist
The rotary valve 19 is rotated and displaced, and the rotary valve 19 is rotated.
The hydraulic pressure from the oil pump is supplied to the right or left chamber of the power cylinder device 12 by the rotation difference of
The front wheels 10, 10 are driven in the direction steered by the steering wheel 18 to reduce the steering force.

In such a steering device,
For example, if you want to change to the strongest understeer characteristics,
The driver turns the dial of the operation unit 34 to "Compliance:
Rotate to the "100%" position.

Then, the control unit 33 causes the second current controller to operate.
The compliance of the actuator bar 20 is read from the map of "compliance-slider position" according to the signal detected by the stroke sensor 30, and the operation unit 34 is read.
Compare with the compliance entered from.

The control unit 33 outputs a control signal corresponding to this difference to the drive circuit 29a to drive the motor 29. Then, the screw shaft 26 rotates, and the slider 25 is slid to the tip side of the second torsion bar 20. As a result, the position for regulating the rotation direction of the second torsion bar 20 is continuously shifted.

When the difference becomes "0", the control unit 33 stops the motor 29. Thereby, the slider-2
5 is the position of the symbol A, that is, “Compliance: 10
0% ". As a result, the second torsion bar 20 is set in a state in which the compliance is 100% and is utilized (torsional rigidity: small).

Here, the second torsion bar 20 is a spring element in series with the first torsion bar 5 of the steering gear 1 and constitutes a considerable part of the overall compliance of the steering system. Moreover, this compliance acts as a factor that reduces the cornering power of the front wheels 10, 10. Therefore, the above setting causes the steering system to be changed to have a tendency toward a strong understeer characteristic.

In order to change to the weakest understeer characteristic, if the dial of the operation unit 34 is rotated to the position of "compliance: 0%", the same as in the case of "compliance: 100%". By action, the slider 25 is now positioned at point B, "compliance: 0%".

As a result, the second torsion bar 20 is set in a state in which compliance is hardly utilized (torsion rigidity: large), and the steering device is changed to a tendency of weak under-steer characteristics.

Further, in the case of changing to an intermediate understeer characteristic, for example, if the dial of the operating portion 34 is rotated to a position of, for example, about "compliance: 50%", the slider 25 is designated by the symbol A this time. It is positioned at a part in the middle of the code B.

As a result, the compliance of the second torsion bar 20 is set to a state of being utilized (torsional rigidity: medium) by about 50%, and the tendency of the intermediate understeer characteristic is changed.

Therefore, the steering characteristics of the steering device can be changed according to the driver's preference, and the vehicle can be provided with both the stability-oriented and sporty-oriented movement characteristics.

Therefore, the dynamic characteristics of the vehicle can be greatly improved, and both performances such as easy bending in a low speed range and stability in a high speed range, which have been conventionally difficult, can be achieved. 5 and 6 show a second embodiment of the present invention.

The second embodiment differs from the first embodiment in that the motor 29 is installed so as not to rotate with the shaft portion 17a (the steering shaft 17). That is, the installation structure of the present embodiment is as follows.

A column cover fixed to a vehicle body (not shown), for example, an inner surface of a column cover 35,
A screw 29, a screw shaft 26, and a stroke sensor 30 are installed. A second slider -40 is slidably screwed into the screw shaft 26. This second slider-40
Is inserted into the detection groove 32 of the stroke sensor 30, and the movement of the slider 40 in the rotational direction is restricted by the groove. A part of the outer circumference of the circular slider 25 is slidably inserted into the U-shaped locking groove 41 formed in the second slider 40, and the second slider 40 The slider 25 can be slid along the axial direction of the second torsion bar 20 in accordance with the slide. Reference numeral 42 denotes a bearing member for rotatably supporting the screw shaft 26 on the column cover 35.

With such an installation structure, the slider 29 is fed around the steering shaft 17 by the feed of the screw shaft 26 without rotating the motor 29, the screw shaft 26, the stroke sensor 30 and the second slider 40. -25 can be moved along the axial direction of the second torsion bar 20 (slider 25, guide bar).
23 side rotates with the steering shaft 17). According to the structure of the second embodiment, since the space around the motor element can be utilized, the space efficiency is superior to that of the structure of the first embodiment. However, in FIGS. 5 and 6, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In each of the above embodiments, an example in which the understeer characteristic is varied has been described as an example. However, it is needless to say that the oversteer characteristic can be varied with the same structure.

In each of the above-described embodiments, the torsion bar is used.
And a slider having a through-hole corresponding to the selection is employed, but the present invention is not limited to this. The position where the rotation direction of the torsion bar is restricted may be changed by an engagement structure which is restricted and movable in the axial direction.

Further, in any of the above-described embodiments,
Although the present invention has been applied to the power steering device, the present invention is not limited to this, and may be applied to a manual steering device.

[0053]

As described above, according to the present invention,
By continuously changing the rigidity of the torsion bar, the steering characteristics of the steering device can be continuously changed.
Therefore , the motion performance of the vehicle can be continuously controlled .

Therefore, the kinetic characteristics of the automobile can be greatly improved, and the flexibility in the middle and low speed range, which has conventionally been difficult, and the stability in the high speed range can both be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a steering device according to a first embodiment of the present invention, together with a control system.

FIG. 2 is a perspective view showing a configuration of a steering device.

FIG. 3 is a cross-sectional view showing a structure that varies the compliance incorporated in a steering shaft of the steering device.

4 is a sectional view taken along line XX in FIG.

FIG. 5 is a sectional view showing a structure for varying compliance, which is a main part of a second embodiment of the present invention.

6 is a cross-sectional view taken along the line YY in FIG.

[Explanation of symbols]

1 ... steering gear, 3 ... rack, 4 ... pinion, 5
... torsion bar for driving valve, 12 ... power cylinder device, 17 ... steering shaft, 17a, 17b
... shaft portion, 18 ... handle, 19 ... rotary valve, 20 ... second torsion bar, 20a ... selection, 25 ... slider , 25a ... through hole, 23 ... guide bar, 26 ... screw shaft, 29 ... Motor, 29a ... Drive circuit, 30 ... Stroke sensor, 33 ... Control part, 34 ... Operation part.

 ───────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Kumakura 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (56) References JP-A-60-71370 (JP, A) Shown 62-170374 (JP, U) Actually opened 61-78780 (JP, U) Actually opened 61-81015 (JP, U)

Claims (1)

(57) [Claims] 1. A steering gear connected to a front wheel, a steering shaft divided in an axial direction for transmitting a displacement of a steering wheel to the steering gear, and a steering shaft provided at one of the divided steering shaft portions, A torsion bar extending toward the axial end of the other divided steering shaft portion, and an axial end of the other divided steering shaft portion
At the side of the torsion bar extending from the coaxial end
A guide member disposed in parallel with the torsion bar and the torsion bar and the guide member.
A plate-like member that is slidably connected along the axial direction of the torsion bar.
A slider and the slider continuously in the axial direction of the torsion bar
A steering device for a vehicle, comprising: