JP2005247255A - Torque detecting apparatus, and power steering apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque detecting apparatus which can quickly detect steering torque inputted to a steering wheel, and further to provide a power steering apparatus having the same. <P>SOLUTION: Torque related information sensors 15 are provided at connected portions 21 of a rim 19 with spokes 20 of the steering wheel 2, respectively. Because steering torque inputted from a driver to the rim 19 of the steering wheel 2 can be detected at a position in the close vicinity of the rim 19, the steering torque applied to the steering wheel 2 can be quickly detected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a torque detection device for detecting a steering torque applied to a steering wheel and a power steering device including the torque detection device.

A power steering device for a vehicle such as an automobile determines a steering assist force applied to a steering mechanism based on a steering torque applied to a steering wheel by a driver, and detects the steering torque. Therefore, a torque sensor is used.
Typically, the torque sensor is provided around a steering shaft that connects the steering wheel and the steering mechanism. The steering shaft is divided into an input side member connected to the steering wheel, an output side member connected to the steering mechanism, and a torsion bar connecting the two members. The torsion bar is twisted according to the steering torque applied to the steering wheel, so that the input side member and the output side member rotate relative to each other by a predetermined amount. The torque sensor detects the steering torque by detecting the relative rotation amount between these two members. However, when the torsion bar is used, there is a problem that the driver feels that the steering rigidity is insufficient due to torsion of the torsion bar.

  On the other hand, some of the torsion bars having torsion (springiness) and low rigidity are abolished (see, for example, Patent Documents 1 and 2). In Patent Document 1, the steering shaft is divided into an input side member and an output side member, a pressing portion is provided on the input side member, a pressure detection element is provided on the output side member, and the torque transmitted between the two members is determined. The steering torque is detected by the pressing portion pressing the pressure detecting element with the applied pressure.

In Patent Document 2, a strain gauge is formed at the central portion in the axial direction of the spoke of the steering wheel to generate a strain according to the applied steering torque, and a strain gauge is attached, and a change in the electrical resistance value of the strain gauge is detected. Thus, the steering torque is detected.
Japanese Patent Application Laid-Open No. 10-104093. Japanese Utility Model Publication No. 63-35931.

  In the case of Patent Literature 1, the steering torque input from the driver to the steering wheel is detected via the input shaft of the steering shaft. That is, since the torque sensor is far from the steering torque input portion of the steering wheel, the input of the steering torque from the steering wheel to the torque sensor is delayed. As a result, the operation of the steering mechanism with respect to the operation of the steering wheel is delayed, and the driver feels that the steering rigidity is insufficient. That is, it is difficult to obtain a steering feeling having a rigidity feeling like a manual steering device.

Also in Patent Document 2, since the strain gauge is provided in the axial center portion of the spoke of the steering wheel, that is, at a position relatively far from the rim of the steering wheel that is normally held by the driver, the strain gauge is connected to the torque sensor. The input of the steering torque is delayed, and there is a problem similar to that of Patent Document 1.
The present invention has been made under such a background, and an object thereof is to provide a torque detection device capable of quickly detecting a steering torque input to a steering wheel and a power steering device including the torque detection device.

  In order to achieve the above object, the present invention provides a torque detecting device for detecting a steering torque applied to a steering wheel including a rim portion and a spoke portion, and a coupling portion between the rim portion and the spoke portion of the steering wheel, or Provided is a torque detection device comprising means for detecting force or distortion in the vicinity thereof, and detecting a steering torque based on the force or distortion detected by the means for detecting force or distortion. .

For example, when the driver of the vehicle holds the steering wheel, the driver usually holds the rim portion of the steering wheel. According to the present invention, since the steering torque input to the rim portion can be detected at a portion extremely close to the rim portion, the steering torque applied to the steering wheel can be quickly detected.
In the present invention, the rim portion of the steering wheel includes an inner rim portion that is connected to the steering shaft via the spoke portion so as to be integrally rotatable, and an outer rim portion that covers the inner rim portion and is rotatable relative to the inner rim portion. Including a rim portion, and includes first and second engaging portions that are provided on either the spoke portion or the inner rim portion and the outer rim portion, respectively, and can be engaged with each other in the rotation direction of the steering wheel. Alternatively, the means for detecting distortion may include a pressure sensitive element interposed between the first and second engaging portions.

In this case, for example, when the driver of the vehicle holds the steering wheel, the driver holds the outer rim portion of the steering wheel. According to the present invention, since the steering torque input to the outer rim portion can be detected at a portion very close to the outer rim portion, the steering torque applied to the steering wheel can be quickly detected.
The present invention also provides the torque detection device, a steering mechanism for driving the steered wheels according to the operation of the steering wheel, and a steering assist force according to the steering torque detected by the torque detection device. And a steering assist force generating means for generating and applying to the steering mechanism.

  According to the present invention, the steering torque applied to the steering wheel can be quickly detected. As a result, the steering mechanism can operate quickly in response to the operation of the steering wheel, and there is a sense of rigidity with excellent responsiveness like a manual steering device. Steering feeling can be obtained.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a power steering apparatus 1 according to an embodiment of the present invention. Referring to FIG. 1, a power steering apparatus 1 includes a steering shaft 3 connected to a steering wheel 2 as a steering member, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, A pinion shaft 7 connected to the intermediate shaft 5 via a universal joint 6 and a steering mechanism 9 including a rack and pinion mechanism connected to the pinion shaft 7 are provided. The steering shaft 3 is formed by a single member and has extremely high rigidity.

The steering mechanism 9 is driven according to the operation of the steering wheel 2 to steer the steered wheels 8, and is arranged to extend in the left-right direction of the vehicle and the pinion 10 provided at the tip of the pinion shaft 7. And a knuckle arm 13 that is coupled to both ends of the steered shaft 11 via tie rods 12 and supports the steered wheels 8.
A rack 14 is formed on a part of the steered shaft 11, and the pinion 10 is engaged with the rack 14. When the steering shaft 3, the intermediate shaft 5, and the pinion shaft 7 are rotationally driven according to the operation of the steering wheel 2, this rotation is converted into axial movement of the steered shaft 11 by the pinion 10 and the rack 14. By the movement of the steered shaft 11 in the axial direction, the knuckle arm 13 is rotated and the steered wheels 8 are steered.

A torque-related information sensor 15 including a force sensor including a pressure-sensitive element as a means for detecting a force applied to the steering wheel 2 is provided. A detection signal from the torque related information sensor 15 is input to a control unit 16 including a microprocessor and the like. Further, a vehicle speed detection signal from a vehicle speed sensor (not shown) is input to the control unit 16.
The control unit 16 calculates a steering torque based on the force detected by the torque related information sensor 15, and further, steering based on the steering torque, the vehicle speed detected by the vehicle speed sensor, etc. The driving of the catching force generating unit 17 is controlled to cause the steering assisting force generating unit 17 to generate a predetermined steering assisting force. The steering assist force generated by the steering assist force generator 17 is applied from the steered shaft 11 to the steering mechanism 9, for example, to assist the driver's steering.

The steering assist force generation unit 17 is for generating a steering assist force according to the steering torque detected as described above and applying it to the steering mechanism 9, and includes a power source (not shown). As the power source, an electric motor can be exemplified, and a hydraulic device including a piston and a cylinder can be exemplified.
The steering wheel 2 includes, for example, a connecting portion 18 connected to one end portion of the steering shaft 3 so as to be integrally rotatable by spline fitting, a circular rim portion 19 for a driver to hold and hold, a connecting portion 18 and a rim. A spoke portion 20 that connects the portion 19 so as to be integrally rotatable is provided. For example, three spoke portions 20 are provided, and one end portion of each spoke portion 20 is coupled to the connecting portion 18. The other end of each spoke 20 is coupled to the rim 19.

  A feature of the present embodiment is that the torque related information sensor 15 is provided in the coupling portion 21 between the rim portion 19 and the spoke portion 20 of the steering wheel 2 so that the steering torque applied to the steering wheel 2 is reduced. A torque detection device 22 for detection is formed so that the steering torque applied to the steering wheel 2 from the driver of the vehicle can be quickly detected. The torque related information sensor 15 may be provided on the rim portion 19 as shown in FIG. 1 or may be provided on the spoke portion 20. When the torque related information sensor 15 includes a force sensor, at least part of torque transmission between the rim portion 19 and each spoke portion 20 is performed via each torque related information sensor 15.

When a driver of a vehicle provided with the power steering apparatus 1 holds the steering wheel 2, the driver usually holds the rim portion 19 of the steering wheel 2.
As described above, according to the present embodiment, the steering torque input from the driver to the rim portion 19 of the steering wheel 2 can be detected at a portion very close to the rim portion 19, and is thus applied to the steering wheel 2. Steering torque can be detected quickly. As a result, the steering mechanism 9 can be quickly operated with respect to the operation of the steering wheel 2, and a steering feeling with a sense of rigidity having excellent responsiveness as in a manual steering device can be obtained.

  Also, unlike the conventional case where the torsion bar is provided on the steering shaft, the steering shaft 3 is formed as a single item to ensure high rigidity, so that the driver does not feel that the steering rigidity is insufficient and is inexpensive. is there. Further, in the conventional case, the torque sensor needs to be disposed in the steering column having a limited arrangement space so as to surround the torsion bar. In the present embodiment, the torque-related information sensor 15 is disposed in the steering column. There is no need to place it in the column. As a result, it has become possible to increase the degree of freedom in designing the shock absorbing structure provided in the steering column.

In the above embodiment, a strain sensor such as a strain gauge as a means for detecting strain is used as the torque related information sensor 15, and the steering torque is detected based on the strain detected by the strain sensor. You may do it. In this case, torque is directly transmitted between the rim portion 19 and the spoke portion 20 of the steering wheel 2.
FIG. 2 is a front view of a torque detection device 22 according to another embodiment of the present invention. In the following, differences from the embodiment shown in FIG. 1 will be mainly described, and the same components will be denoted by the same reference numerals and description thereof will be omitted. With reference to FIG. 2, in the present embodiment, torque-related information sensors 15 are provided in the vicinity of coupling portion 21 of steering wheel 2. Specifically, each torque-related information sensor 15 is provided on the rim portion 19 and is provided in a pair so as to sandwich the corresponding spoke portion 20. As the torque related information sensor 15, a force sensor made of a piezoelectric element or the like can be exemplified, and a strain sensor made of a strain gauge or the like can be exemplified. When the torque related information sensor 15 includes a force sensor, at least part of torque transmission between the rim portion 19 and each spoke portion 20 is performed via each torque related information sensor 15. Further, when the torque related information sensor 15 includes a distortion sensor, torque is directly transmitted between the rim portion 19 and the spoke portion 20.

In the present embodiment, the torque related information sensor 15 may be provided in each spoke portion 20. In this case, the torque related information sensor 15 is disposed on the rim side at least with respect to the central portion in the axial direction of the corresponding spoke portion 20.
In each embodiment shown in FIGS. 1 and 2, the number of the spoke portions 20 of the steering wheel 2 may be one or two, or may be four or more. Further, the number of torque related information sensors 15 provided corresponding to one coupling portion 21 may be one or two.

FIG. 3 is a cross-sectional front view of a torque detection device 22 according to still another embodiment of the present invention, and FIG. 4 is an enlarged view around the torque-related information sensor 15 of FIG.
Referring to FIGS. 3 and 4, the rim portion 19 of the steering wheel 2 includes an inner rim portion 23 connected to the steering shaft 3 through the spoke portion 20 and the connecting portion 18 so as to be integrally rotatable, and the inner rim portion 23. And an outer rim portion 24 that can rotate relative to the inner rim portion 23.

The feature of the present embodiment is that the spoke portion 20 and the outer rim portion 24 are opposed to each other in the rotation direction R (circumferential direction) of the steering wheel 2 and can be engaged with each other. The portions 25 and 26 are formed, and the torque-related information sensor 15 is interposed between the engaging portions 25 and 26.
Specifically, a force sensor composed of a pressure sensitive element such as a piezoelectric element can be exemplified as the torque related information sensor 15. For example, four spoke portions 20 are provided. One end portion of each spoke portion 20 is coupled to the connecting portion 18, and the other end portion of each spoke portion 20 is coupled to the inner rim portion 23. The outer rim portion 24 is formed by, for example, an annular hollow member. The outer rim portion 24 is formed with insertion holes 27 through which the corresponding spoke portions 20 are inserted.

  One or a plurality of (single in this embodiment) spoke portions 20 have a pair of first engaging portions 25 corresponding to the rotation direction R, and the inner peripheral surface of the corresponding insertion hole 27 is It has a pair of 2nd engaging part 26 which respectively opposes a pair of said 1st engaging part 25, and between each corresponding 1st and 2nd engaging parts 25 and 26, a torque related information sensor 15 is interposed. That is, the corresponding first and second engaging portions 25 and 26 are engaged with each other via the corresponding torque related information sensor 15.

The torque related information sensor 15 is fixed to one or both of the first and second engaging portions 25 and 26. A small gap (for example, 0.5 mm) may be formed between the engagement portion 25 or the engagement portion 26 on the side where the torque-related information sensor 15 is not fixed and the torque-related information sensor 15, or a gap is formed. It may not be done.
When the driver of the vehicle holds the steering wheel 2, the driver holds the outer rim portion 24 of the steering wheel 2. When the driver holds the outer rim portion 24 and rotates the steering wheel 2 in any rotation direction, the steering torque applied from the driver to the outer rim portion 24 is spoken via the corresponding torque-related information sensor 15. Is further transmitted to the steering mechanism 9 (see FIG. 1) via the steering shaft 3 and the like.

  As described above, according to the present embodiment, the steering torque input from the driver to the outer rim portion 24 can be detected at a position very close to the outer rim portion 24, and is thus applied to the steering wheel 2 from the driver. Steering torque can be detected quickly. As a result, the steering mechanism 9 can be quickly operated with respect to the operation of the steering wheel 2, and a steering feeling with a sense of rigidity having excellent responsiveness as in a manual steering device can be obtained. Furthermore, by providing two torque-related information sensors 15, the direction in which the steering torque acts can also be detected.

In the embodiment of FIG. 3, one of the pair of torque related information sensors 15 is connected between the first engaging portion 25 provided on the other spoke portion 20 and the second engaging portion 26 corresponding thereto. The value of the steering torque applied to the steering wheel 2 and the direction in which the steering wheel 2 is applied may be detected using both the torque related information sensors 15.
FIG. 5 is a partial sectional view of an essential part of still another embodiment of the present invention. In the following, differences from the embodiment shown in FIG. 4 will be mainly described, and the same components are denoted by the same reference numerals and description thereof will be omitted. Referring to FIG. 5, in the present embodiment, first and second protrusions 31 are formed on one of inner rim portion 23 and outer rim portion 24, and recess 30 is formed on the other, respectively. Engaging portions 25 and 26 are provided.

For example, the convex portion 31 formed on the inner peripheral surface of the outer rim portion 24 is accommodated in the concave portion 30 formed on the inner rim portion 23. The convex portion 31 includes a pair of second engaging portions 26, and the inner wall surface of the concave portion 30 includes a pair of first engaging portions 25. In this case, as the torque related information sensor 15, a force sensor composed of a pressure sensitive element such as a piezoelectric element can be exemplified.
In the present embodiment, a plurality of sets of concave portions 30 and convex portions 31 are provided, and torque related between the first and second engaging portions 25 and 26 corresponding to each other in the concave portions 30 and convex portions 31 of the respective sets. An information sensor 15 may be interposed. Further, the concave portion 30 may be formed in the outer rim portion 24 and the convex portion 31 may be formed in the inner rim portion 23. Furthermore, in each embodiment shown in FIGS. 4 and 5, the number of the spoke portions 20 may be three or less, or may be five or more.

The present invention is not limited to the above embodiments. For example, a pressure sensor or the like may be used as the force sensor, and a magnetostrictive element or the like may be used as the strain sensor. Further, the steering assist force of the steering assist force generator 17 may be applied to the steering shaft 3 via a speed reduction mechanism (not shown).
In addition, the present invention can be applied to a so-called steer-by-wire (SBW) device in which the mechanical connection between the steering shaft and the steering mechanism is released. Is possible.

It is a mimetic diagram showing a schematic structure of a power steering device of one embodiment of the present invention. It is a front view of the torque detection apparatus of other embodiment of this invention. It is a cross-sectional front view of the torque detection apparatus of further another embodiment of this invention. FIG. 4 is an enlarged view around a torque related information sensor in FIG. 3. It is a partial cross section figure of the principal part of another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power steering apparatus 2 Steering wheel 3 Steering shaft 8 Steering wheel 9 Steering mechanism 15 Torque related information sensor (means for detecting force or distortion, pressure sensitive element)
17 Steering assist force generator (steering assist force generator)
19 Rim part 20 Spoke part 21 Coupling part 22 Torque detection device 23 Inner rim part 24 Outer rim part 25 First engagement part 26 Second engagement part R Rotation direction

Claims (3)

  In a torque detection device for detecting a steering torque applied to a steering wheel including a rim portion and a spoke portion, for detecting force or distortion at or near a coupling portion between the rim portion and the spoke portion of the steering wheel. A torque detection apparatus comprising: means for detecting a steering torque based on the force or distortion detected by the means for detecting force or distortion. 2. The rim portion of the steering wheel according to claim 1, wherein the rim portion of the steering wheel is connected to the steering shaft via the spoke portion so as to be integrally rotatable, and the outer rim covers the inner rim portion and is rotatable relative to the inner rim portion. Including
A first engagement portion and a second engagement portion, which are provided on either the spoke portion or the inner rim portion and the outer rim portion, respectively, and can be engaged with each other in the rotation direction of the steering wheel;
The means for detecting the force or strain includes a pressure sensitive element interposed between the first and second engaging portions. The torque detection device according to claim 1 or 2,
A steering mechanism for driving the steered wheels by driving according to the operation of the steering wheel;
A power steering device, comprising: a steering assist force generating means for generating a steering assist force according to the steering torque detected by the torque detection device and applying the generated steering assist force to the steering mechanism.

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