JPH05139321A - Steering device for vehicle - Google Patents

Abstract

PURPOSE:To drastically improve the motion characteristic of a vehicle. CONSTITUTION:A steering shaft 17 is divided in the axial direction and a torsion bar 20 extending towards one divided shaft part 17b is installed onto the other shaft part 17a, and a shift element which is connected with the edge part of the shaft part 17b and can shift along the torsoion bar 20 is installed on the periphery of the torsion bar 20. The first engagement part is installed along the axial direction on the outer peripheral surface of the torsion bar 20, and the second engagement part which is engaged to be regulated for the first engagement part and for the peripheral direction of the torsion bar 20 and to be shiftable for the axial direction of the torsion bar 20 is installed on the shifting element, and an operating mechanism for operating the shifting element along the axial direction of the torsion bar 20 is installed. Accordingly, accompanied with the shift of the shifting element, the point where the revolution direction of the torsion bar 20 is restrained shifts, and the compliance for determining the motion characteristic of a vehicle can be varied.

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 front wheels of an automobile.

[0002]

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

Conventionally, in such a steering apparatus, a steering gear (for example, a rack and pinion type et) is constructed by providing a torsion bar between the input and output sections.
c. ) Is connected to a steering wheel via a steering shaft, and the steering gear is twisted by a torsion bar to supply 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.

In such a steering device, the rotation of the steering wheel transmitted through the steering shaft and the torsion bar is converted into a displacement in the steering direction by the steering gear to steer the front wheels. The rotary valve is rotationally displaced according to the torsion of the torsion bar (due to road surface resistance) generated during this steering, 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 motion characteristics of an automobile are basically governed by the size 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 characteristics (steering angle) If the speed is kept constant and the turning radius increases, the turning radius tends to increase. If the cornering power of the front wheels increases, the understeer characteristic tends to decrease.

When the tendency of the understeer characteristic is strong, it becomes difficult to bend in the medium and low speed range, but on the other hand, the stability oriented vehicle has high stability in the high speed range. -It becomes a car that is oriented towards the tee.

Normally, in an automobile, it is difficult to achieve both the flexibility in the medium and low speed range and the stability in the high speed range. Therefore, either stability-oriented or sporty-oriented is selected. Are forced to do so. Generally, a weak understeer characteristic is given to the vehicle. For this reason,
I had a situation where I couldn't 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 system capable of significantly improving the motion characteristics of a vehicle.

[0010]

In order to achieve the above object, a vehicle steering system according to the present invention is configured such that a steering shaft for transmitting a displacement of a steering wheel to a steering gear is axially divided, and one of the divided steerings is used. A torsion bar extending toward the axial end of the other steering shaft portion is provided at the shaft end of the shaft portion, and a torsion bar is provided around the torsion bar at the end portion of the other steering shaft portion. Provided with a movable element arranged around the axial direction of the torsion bar, and provided with a first engaging portion along the axial direction on the outer peripheral surface of the torsion bar, The mover restricts the circumferential direction of the torsion bar, and the torsion bar
The first so as to be movably engaged in the axial direction of
A second engaging portion that engages with the engaging portion and an operating means for operating the moving element along the axial direction of the torsion bar.

[0011]

According to the vehicle steering system of the present invention, when the moving member is moved along the axial direction of the torsion bar by the operating means, the rotation direction of the torsion bar is restricted according to the movement of the moving member. Is displaced. 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 the state in which the compliance (softness = the reciprocal of rigidity) is fully utilized to the state in which it is hardly utilized. Here, in a steering device, it is known that 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" change).

Therefore, it is possible to adjust the steering characteristic, which has been unique in the past, and to give all the understeer characteristics (or all the oversteer characteristics) to one vehicle (the movement characteristics 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 of. FIG. 2 is a diagram of the structure of a power steering device for an automobile (vehicle) to which the present invention is applied, for example, and FIG. 1 is a schematic diagram thereof, and 1 is, for example, a rack and pinion type steering gear.

The steering gear 1 incorporates a rack 3 (output section) and a pinion 4 which meshes with the rack 3 in a casing 2, and a shaft end 6 (input section) of the pinion 4 is used for driving a valve. It is configured by being connected via a first torsion bar 5.

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

A steering wheel 18 is connected to a shaft end 6 projecting from an upper end of the casing 2 via a steering joint 16 and a steering shaft 17. When a rotational displacement is input from the steering wheel 18, the steering shaft is operated. 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 well-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 (not 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. As a result, according to the displacement of the rotary valve 12, the 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-shaped selections 20a (corresponding to the first engaging portion) are formed along the axial direction.

On the outer peripheral surface of the second torsion bar 20, a disk-shaped slider 25 (corresponding to a moving element) is slidably fitted. That is, as shown in FIG. 4, the slider 25 has a through hole 25 having an uneven shape corresponding to the cross-sectional shape of the second torsion bar 20 at the center.
The through hole 25a is slidably fitted in the selection portion of the second torsion bar 20.

At the end of the shaft portion 17a, a pipe 21 having a flange portion 21a at its tip is provided in a protruding manner.
Further, a short pipe portion 22 having a flange portion 22a at its tip is slidably fitted into the end portion of the shaft portion 17b. The pipe portion 22 is connected to a shrinkable 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. The flange portion 21a and the flange portion 22a form a pair.

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

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

As a result, the slider 25 is guided by the guide bar.
If you slide along 23, the second torsion bar
The position in which the rotation 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
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 where the compliance of the second torsion bar 20 is 100% and is utilized (compliance: 100%). The point shown is
The point (compliance: 0%) where the compliance of the second torsion bar 20 is hardly utilized 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 between the flange portions 21a and 22a. As shown in FIG. 4, this male screw portion is rotatably inserted 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 the motor 29 (driving source) installed on the outer peripheral portion of the motor 1 and the slider-2 is rotated as the motor 29 rotates.
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 flan portions 21a and 22a,
A stroke sensor 30 is provided along the movement locus of the protruding piece 28. In addition, a convex portion 31 that serves as a detected element is formed on the projecting piece portion 28. And this convex part 31 is
Formed along the length direction of the stroke sensor 30,
The second torsion bar is inserted into the detection groove 32 as a detection portion, and the second torsion bar is positioned from the position of the convex portion 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 is composed of, for example, a microcomputer and its peripheral circuits. A dial type operation unit 34 for variably operating the compliance is connected to the control unit 33. The 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) corresponding to the compliance of the second torsion bar 20 is set. ing.

Further, the control unit 33 includes, for example, the compliance input from the operation unit 34 and the stroke sensor 3.
The function of comparing the compliance read from the map according to the output signal of 0 and the function of controlling the drive circuit 29a so that the difference between the comparison results in "0" are set. Predetermined position for compliance (the second torsion bar 20 "A ~
The slider 25 is positioned at a position "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%".
The compliance of can be set arbitrarily (corresponding to the 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 car body (not shown).

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 are sequentially transmitted to the pinion 4 to drive the rack 3 in the direction steered by the handle 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 rotationally displaced, and this rotary valve 19
The oil pressure from the oil pump is supplied to the right chamber or the left chamber of the power cylinder device 12 due to the rotation difference of
The front wheels 10, 10 are driven in the steering direction 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 characteristic,
The driver sets the dial on the operation unit 34 to "Compliance:
Rotate to the "100%" position.

Then, the control unit 33 causes the current second to-
The compliance of the command 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 that regulates the rotation direction of the second torsion bar 20 continuously shifts.

The control unit 33 stops the motor 29 when the compared difference becomes "0". This allows slider-2
5 is the point of code A, that is, "compliance: 10
0% ”. As a result, the second torsion bar 20 is set in a state where 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, ie, "compliance: 0%".

As a result, the second torsion bar 20 is set in a state where the compliance is hardly utilized (torsional rigidity: large), and the steering device is changed to have a tendency of a weak understeer characteristic.

Further, for example, in the case of changing to an intermediate understeer characteristic, if the dial of the operating portion 34 is rotated to a position of, for example, "compliance: 50%", then the slider 25 is designated by the symbol A. 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 characteristic of the steering device can be changed according to the driver's preference, and the vehicle can be provided with both stability-oriented and sporty-oriented movement characteristics.

Therefore, the dynamic characteristics of the automobile can be greatly improved, and both performances such as flexibility in the medium and low speed range and stability in the 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 together with the shaft portion 17a (steering shaft 17) so as not to rotate. That is, the installation structure of the present embodiment is as follows.

A column cover fixed to the vehicle body (not shown), for example, the inner surface of the column cover 35, has a mower.
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 periphery 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 is 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, the space around the motor element can be utilized, and therefore 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 first embodiment described above are designated by the same reference numerals, and the description thereof is omitted.

In each of the above-mentioned embodiments, the one in which the understeer characteristic is changed has been described as an example, but it is needless to say that the oversteer characteristic can be changed in the same structure.

Further, in the above-mentioned embodiment, the torsion bar is used.
The engaging structure is used in which the selection provided on the above and a slider having a through hole corresponding to the selection are combined, but the present invention is not limited to this, and the engaging structure is not limited to the rotation direction of another torsion bar. It is also possible to change the position for restricting the rotation direction of the torsion bar with an engaging structure that allows restriction and movement in the axial direction.

Furthermore, in any of the above-mentioned embodiments,
Although the present invention is 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,
The steering characteristics of the steering device can be changed, and the vehicle can be provided with both stability-oriented and sporty-oriented movement characteristics.

Therefore, the dynamic characteristics of the automobile can be greatly improved, and it is possible to achieve both the bendability in the medium to low speed range and the stability in the high speed range, which have been conventionally difficult.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a steering system 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 is incorporated in a steering shaft of a steering device to change compliance.

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

FIG. 5 is a cross-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 (moving element), 25a ... through hole (second engaging portion) ), 23 ... Guide bar, 26 ... Screw shaft, 29
... motor, 29a ... drive circuit, 30 ... stroke sensor, 33 ... control section, 34 ... operation section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Kumakura 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (1)

[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 an axial end of one of the divided steering shaft portions, A torsion bar extending toward the axial end of the other divided steering shaft portion and a portion of the torsion bar connected to the end portion of the other divided steering shaft portion around the torsion bar. A mover provided so as to be movable along the axial center of the torsion bar, a first engaging portion provided on the outer peripheral surface of the torsion bar along the axial direction, and a mover provided on the mover. , The first engaging portion, and
A second engaging portion that restricts the circumferential direction of the torsion bar and engages so as to be movable in the axial direction of the torsion bar; A steering device for a vehicle, comprising: an operating unit that operates in the axial direction of the vehicle.