JPH05124523A - Torque detector for motor-driven type power steering - Google Patents

Abstract

PURPOSE:To obtain an exceedingly simple structure by detecting the torque between an input shaft and output shaft with high precision, without particularly increasing the working precision. CONSTITUTION:An input shaft 1 and an output shaft 2 are connected through a torsion bar 3, and a slidable body 4 having a pressing part 4b formed on the outer peripheral part is revolved together with the output shaft 2, and can be slided in the axial direction, and both the contact parts 8 and 8 of a swing member A1 in which an annular body 6 can be swung around two contact parts 8 and 8 formed at both the edge parts in the diameter direction of the annular body 6 are brought into contact with the pressing part 4b of the slidable body 4, and on the other surface side of the annular body 6, one side at the crossing position nearly at right angles with the line joining both the contact parts 8 and 8 is supported in swingable manner, and the other side is brought into contact with a detector 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device for an electric power steering, which has a simple structure and can improve the accuracy and reliability of the detecting function. It is possible to achieve an accurate and reliable operation without increasing the working accuracy of parts, the assembly accuracy at the time of manufacturing, and the like, which solves the above problems.

[0002]

2. Description of the Related Art In recent years, electric power steering has been widely used, and there are various structures in the electric power steering.

As its main structure, the input shaft on the steering wheel side and the output shaft equipped with a steering device are connected by a torsion bar, and the input shaft is connected to the input shaft by reaction force such as resistance force received by the tire from the road surface. The rotation angle of the output shaft differs from that of the output shaft due to the torsion of the torsion bar.

Due to the difference in rotation angle between the input shaft and the output shaft, a cylindrical sliding member having a collar portion formed on the outer periphery of the input shaft is slid through a motion direction converting mechanism such as a cam mechanism.
When the steering operation is performed by appropriately operating the sensing unit of a detector such as a potentiometer that converts a movement amount into an electric amount such as a voltage by the sliding action of the sliding member to start the electric motor and adjust the torque. Is helping the operation of.

[0005]

As described above, when a rotational angle difference occurs between the input shaft and the output shaft, the displacement of the input shaft in the rotational direction is directly transferred to the movable member by the cam mechanism or the like. It is converted into a change in direction and detected by a detector such as a potentiometer.

Here, the movable member is formed with a flange portion for operating the detector, and when the movable member moves, it moves in the axial direction while rotating with the output shaft in accordance with the rotation angle difference. Therefore, a bearing is provided between the detection operation member and the detection operation member so as to move in the axial direction without rotating.

In such a conventional structure, the accuracy of the engagement surface between the movable member and the detection actuating member, such as flatness and axial perpendicularity, must be considerably high.
In reality, high precision machining increases cost and makes extremely accurate manufacturing difficult, and even when the movable member is formed accurately, it is difficult to assemble the output shaft and the movable member. As a result, the flange of the movable member tilts with respect to the output shaft due to this, and even if it is slightly inclined, the detection actuating body of the detector such as the potentiometer is separated from the shaft center. Since it is in the position, there is a problem that the accurate operation of the detector cannot be expected.

[0008]

Therefore, as a result of earnest studies to solve the above problems, the inventor has found that the present invention connects the input shaft and the output shaft with a torsion bar and presses them on the outer peripheral portion. Oscillation that allows the sliding body having the formed portion to rotate along with the output shaft and slide in the axial direction so that the annular body can swing about two contact portions formed at both ends in the diameter direction of the annular body. Both contact portions of the member are brought into contact with the pressing portion of the sliding body, and one side of the other surface of the annular body that is substantially orthogonal to the line connecting both contact portions is swingably supported and the other side is detected. The torque detection device for electric power steering that comes into contact with the device can be operated accurately and reliably without increasing the working accuracy of parts and the assembly accuracy during manufacturing. It was done.

[0009]

Embodiments of the present invention will be described below with reference to FIGS.

Reference numeral A is a torque detecting portion of the electric power steering apparatus, in which the input shaft 1 and the output shaft 2 are connected by a torsion bar 3, and as shown in FIG. A cylindrical sliding body 4 is provided so as to be concentric with the input shaft 1 and the output shaft 2.

As shown in FIG. 1 (b), the input shaft 1 is provided with a handle H, and the output shaft 2 is connected to the steering system S via a joint.

As shown in FIG. 2, the input shaft 1 and the output shaft 2 are connected by a torsion bar 3, and the rotation of the input shaft 1 rotates to the output shaft 2 via the torsion bar 3. Is to be transmitted.

The torsion bar 3 connecting the input shaft 1 and the output shaft 2 causes a difference in the rotation angle between the output shaft 2 and the input shaft 1 due to the reaction force received by the tire from the road surface. At that time, the torsion bar 3 is twisted.

At the connecting portion between the input shaft 1 and the output shaft 2, as shown in FIG. 2, first, an engaged portion 1a is formed on one end of the input shaft 1 in the axial direction, and one end of the output shaft 2 in the axial direction is formed. An engaging portion 2a is formed on the engaging portion 2a, and the engaged portion 1a and the engaging portion 2a have an appropriate gap and are configured to be engageable.

The engaged portion 1a of the input shaft 1 is, as shown in FIGS. 1A and 2, specifically, a predetermined width so that the outer shape of the end portion of the input shaft 1 is substantially convex. Is formed as a flat plate-shaped protruding body having two parallel flat surfaces, and the engaging portion 2a of the output shaft 2 is a concave cutout portion into which the convex-shaped flat plate-shaped protruding body can be loosely inserted. Formed, engaging portion 2
When a is loosely inserted in the engaged portion 1a, the two are appropriately spaced so that they are normally in a non-contact state.

When the output shaft 2 rotates via the torsion bar 3 due to the rotation of the input shaft 1, if the torsion of the torsion bar 3 is within a predetermined range, the engaging portion 2a and the engaged portion 1a are separated from each other. The rotation is transmitted from the input shaft 1 to the output shaft 2 without contact.

In the sliding body 4, a pressing portion 4b is formed on the outer peripheral surface of a cylindrical portion 4a, the inside of the cylindrical portion 4a is formed to penetrate, and the output shaft 2 is inserted into the cylindrical portion 4a. Further, as shown in FIG. 5, the pressing portion 4b is formed in a disk-shaped brim shape with respect to the cylindrical portion 4a.
It is formed integrally with the cylindrical portion 4a or is formed as a separate material.

In the structure in which the pressing portion 4b is integrated with the cylindrical portion 4a, the pressing portion 4b and the boss portion 4c are integrally formed as shown in FIG.

The sliding body 4 is configured to rotate with the rotation of the output shaft 2 and to be slidable in the axial direction of the output shaft 2. As a specific example thereof, the sliding body 4 is slidable in the cylindrical portion 4a. A moving locking portion 4d and a sliding locked portion 2b are formed at the end of the output shaft 2. The sliding locking portion 4d is a sliding locked portion 2
It is locked to b, and specifically, the sliding locking portion 4d.
Is formed in a projecting shape from the inner peripheral surface of the cylindrical portion 4a, and the locked portion 2b for sliding is formed in a groove shape along the axial direction on the outer peripheral surface of the end portion of the output shaft 2. The portion 2b is inserted into the sliding locking portion 4d so that the sliding body 4 slides in the axial direction at the end portion of the output shaft 2 (see FIG. 2).

Further, the sliding motion of the sliding body 4 is appropriately adjusted in the axial direction by the rotation of the input shaft 1 when a difference occurs between the rotation angle of the input shaft 1 and the rotation angle of the output shaft 2. It is configured to slide, specifically, by the sliding engagement portion 5, specifically, the guide inclined portion 5a and the guide pin 5b, and as shown in FIG. The slanted guide portion 5a formed as an elongated hole has a cylindrical portion 4 of the sliding body 4.
The guide pin 5b, which is formed on a and has a protruding shape, is provided on the input shaft 1.
The guide pin 5b is inserted into and engaged with the guide inclined portion 5a, and the guide pin 5b acts on the guide inclined portion 5a as the input shaft 1 rotates, so that the sliding body 4 is connected to the output shaft 2 and the input shaft 1. It slides in the axial direction.

Further, when a difference in rotation angle occurs between the input shaft 1 and the output shaft 2, the sliding body 4 is rotated by the rotation of the input shaft 1.
Is not limited to the above-mentioned embodiment as long as it has a structure capable of appropriately sliding in the axial direction of the input shaft 1.

Reference numeral A ₁ denotes a swinging member, and as shown in FIG. 5, the annular body 6 has a through hole 7 formed in the center of the disk body to form a substantially ring shape, and one side surface of the annular body 6 is formed. In, the contact portions 8, 8 are formed symmetrically on both sides of the center of the through hole 7, and the swinging member A ₁ can swing about the contact portions 8, 8.

The contact portions 8 and 8 are formed in a mountain-like shape protruding from the front surface of the annular body 6 and have a pointed tip. When the contact portions 8 and 8 come into contact with another member, they are in line contact or two-point contact state. Further, as another embodiment of the contact portions 8 and 8, there are not-illustrated ones formed in a plate shape with a sharp tip, one formed in a shaft shape, and the like. The structure is not limited to the above as long as the annular body 6 swings around the location.

The oscillating member A ₁ has one end in a direction orthogonal to the line connecting the contact portions 8, 8 oscillatably supported, and specifically, the contact portion 8, of the annular body 6, A support recess 9 is formed on the surface opposite to the surface on which 8 is formed, and the other end of the annular body 6 is connected to a detector 12, and specifically, to a sensing portion 12a of the detector 12. The sensing portion receiving surface 10 is formed in a concave shape in cross section so as to be connected (see FIG. 4).

Then, as shown in FIG. 4, the tip end of the support shaft 11 mounted in the casing 15 is pivotally supported at the support concave portion 9 formed in the annular body 6 so as to be swingable. The oscillating member A ₁ oscillates around the supporting concave portions 9 as fulcrums.

In the swing member A ₁ , the cylindrical portion 4a of the sliding body 4 is loosely inserted into the through hole 7 and the pressing portion 4 of the sliding body 4 is inserted.
It is arranged on the input shaft 1 side of the pressing portion 4b of the sliding body 4 so that the contact portions 8 and 8 come into contact with each other on b. When the sliding body 4 slides, the swinging member A ₁ moves to the pressing portion 4b. Being pressed,
The sensing portion receiving surface 10 of the swinging member A _{1 is} the sensing portion ₁ of the detector 12.
2a and controls the torque of the electric motor M.

The above operation will be described in further detail. The input shaft 1
When there is a difference in rotation angle between the input shaft 1 and the output shaft 2, the sliding engagement portion 5 between the input shaft 1 and the slide member 4 causes the slide member 4 to move.
Has a structure in which it moves along the axial direction of the input shaft 1 and the output shaft 2, and the swing member A ₁ has one end on a line orthogonal to the line connecting both contact portions 8 and 8 supported with the support concave portion 9. The shaft 11 and the contact portions 8, 8 are configured to be pivotally supported by the shaft 11, while the contact portions 8 and 8 are in contact with the pressing portion 4b while the sliding body 4 slides.
b moves to press the contact portions 8 to move the swinging member A ₁ appropriately.

The 9 positions of the supporting recesses do not change by the support shaft 11 and do not move, and as a result, as shown in FIG. 4, the swinging member A ₁ is in contact with the detector 12, that is, the supporting member. Sensing part receiving surface 10 located on the opposite side of the recess 9
The location is movable in the front-back direction.

Further, the contact between the oscillating member A ₁ and the detector 12 is such that the rod-shaped sensing portion 12a can be moved into and out of the main body of the detector 12 by an elastic material such as a spring, and is always projected. When the contact portion between the annular body 6 of the swinging member A ₁ and the detector 12, that is, the formation portion of the sensing portion receiving surface 10 of the swinging member A ₁ is close to the detector 12, the sensing portion 12a is made of an elastic material. When the sensing portion 12a is pushed away from the detector 12 and the sensing portion 12a is separated from the detector 12, the sensing portion receiving surface 10 is formed by the elastic material of the sensing portion 12a.
Are separated from the detector 12.

Specifically, a potentiometer is used as the detector 12, the sensing part 12a has an axial shape, and the axial sensing part 12a moves into and out of the main body of the detector 12 to detect the positional displacement amount. Converted to electrical displacement.

As shown in FIGS. 1 (a), 1 (b) and 2, the electric motor M is provided with a worm gear 13, and the output shaft 2 is provided with a wheel gear 14, and the detector 12 allows the electric motor to move. M is started, and the detector 12 converts the positional displacement amount of the oscillating member A ₁ displaced by the rotation of the input shaft 1 into an electrical displacement amount, while appropriately controlling the torque of the electric motor M, the worm gear The rotation operation of the output shaft 2 is assisted via the wheel gear 13 and the wheel gear 14.

[0032]

When the steering wheel H is operated to cause a rotation angle difference between the input shaft 1 and the output shaft 2 via the torsion bar 3, the sliding engagement portion 5 operates and the sliding body 4 causes the output shaft 2 to move. And moves along the axial direction of the input shaft 1.

The sliding direction of the sliding body 4 moves in the front-rear direction (the same direction as the axial direction of the input shaft 1 and the output shaft 2), and the pressing portion 4b also moves back and forth, so that the swinging member A ₁ moves. It contacts both contact parts 8, 8.

The oscillating member A ₁ oscillates with the support recess 9 as a pivot point according to the movement of the pressing portion 4b, and the sensing section of the detector 12 existing on the side opposite to the support recess 9 side which is the pivot point. 1
At the point of contact with 2a, the sensing portion receiving surface 10 has the sensing portion 12
In this case, the a is moved in and out to start the electric motor M and control the torque, and assists the rotation of the output shaft 2 via the worm gear 13 and the wheel gear 14 on the output shaft 2.

Further, when the pressing portion 4b of the sliding body 4 is formed inaccurately due to the work precision, or due to the looseness of the assembly of the output shaft 2 and the sliding body 4, the pressing portion 4b becomes the output shaft 2 and the input shaft. In the case where the contact portion 8b of the oscillating member A ₁ and the oscillating member A ₁ are inclined by an angle θ without forming a vertical surface with respect to FIG. As shown in FIG. 8 and FIG. 9 (state in which the pressing portion 4b rotates counterclockwise as viewed from the output shaft 2 side), the portion 4b rotates clockwise as viewed from the output shaft 2 side). , Pressing section 4 respectively
By making contact with the most projecting part and the most retracted part of b, the contact part between the swinging member A ₁ and the sensing part 12a of the detector 12 is the most projecting part of the pressing part 4b and the most retracted part. Is an intermediate position of the difference L in the axial direction of the detector 1 and corrects the tilt angle θ and the like due to insufficient precision of the pressing portion 4b, and the detector 1 based on the play between the sliding body 4 and the output shaft 2 and the like.
Make the sensing state of 2 extremely accurate.

[0036]

According to the present invention, the input shaft 1 and the output shaft 2 are provided.
Are connected to each other by the torsion bar 3, and the sliding body 4 having the pressing portion 4b formed on the outer peripheral portion is rotated with the output shaft 2 and slidable in the axial direction, and is formed at both ends in the diameter direction of the annular body 6. The two contact portions 8 and 8 of the swinging member A ₁ which allows the annular body 6 to swing around the two contact portions 8 and 8 are brought into contact with the pressing portion 4b of the sliding body 4 so that the annular body 6 A torque detecting device for an electric power steering, in which one side of a position substantially orthogonal to a line connecting the contact portions 8 on the other surface side is swingably supported and the other side is in contact with a detector 12 As a result, firstly, it becomes possible to detect the torque between the input shaft 1 and the output shaft 2 with high accuracy without particularly increasing the working accuracy, and secondly, the structure is extremely simplified. There are various effects such as being able to.

To describe these effects in detail, the rocking member A ₁ has contact portions 8, 8 formed on both sides of the center of the annular body 6, and the annular body 6 is centered around the contact portions 8, 8. As a result, the rocking member A ₁ is rocked, and its contact portion 8,
When 8 is brought into contact with the pressing portion 4b of the sliding body 4, it is in a two-point contact state on the surface of the pressing portion 4b.

As a result, as shown in FIG. 4, the pressing portion 4b of the sliding body 4 has a low working precision, the pressing portion 4b of the sliding body 4 is formed somewhat inaccurately, and the axial direction of the output shaft 2 is increased. If it is inclined by an angle θ from the vertical plane,
Alternatively, even if the pressing portion 4b is accurately formed with respect to the cylindrical portion 4a of the sliding body 4, the sliding body 4 and the output shaft 2 are in a sliding relationship, and a working precision for obtaining a necessary sliding clearance is provided. Even if there is a tilt angle θ of the sliding body 4 with respect to the output shaft 2 caused by the looseness of the assembly of the output shaft 2 and the sliding body 4 caused by the above, the contact position of the swinging member A _{1 with} the detector 12 is Since it is located at an intermediate position (or a substantially intermediate position) between the contact portions 8 and 8, the tilt angle or the distortion of the pressing portion 4b can be appropriately corrected and the detector 12 can be operated very accurately. You can

That is, in the pressing portion 4b which has a low working precision and is formed inaccurately, the contact portions 8, 8 of the swinging member A ₁ are located at the intermediate points between the most protruding portion and the most recessed portion. when in contact, the contact portion between the detector 12 present halfway between the both contact portions 8, as shown in FIG. 6, the rocking member a ₁ cut the handle H to the left detector 12, or as shown in FIG. 8, when the swinging member A ₁ comes to the right and moves away from the detector 12, the inclination of the pressing portion 4b changes in the axial direction of the output shaft 2. when becomes θ against, although the both contact portions 8 positions of the swinging member a ₁ step L is generated in the axial direction of the output shaft 2, the contact of the detector 12 of the swing member a ₁ position, i.e., the contact between the sensing portion 12a can be reduced to half of the step L, the swinging member a ₁ and the detection Points of contact with the sensing portion 12a of the 12, the detector 12 can be in the most appropriate position that can be accurately operated.

As described above, the swing member A ₁ and the detector 12
Since the contact point with the sliding body 4 is substantially in the axial direction between the most protruding portion and the most recessed portion of the inaccurately formed pressing portion 4b of the sliding body 4, The pressing portion 4b can be brought into a state substantially equivalent to that in which the pressing portion 4b is formed so as to be exactly orthogonal to each other, and the detector 12 can be operated accurately.

Therefore, the pressing portion 4b of the sliding body 4 having a disc shape or the like is used.
Is not orthogonal to the sliding direction, and even if there is an error due to machining such as a slight inclination, the contact portions 8 on both sides of the central portion of the swinging member A ₁ absorb the error. Since the swinging member A ₁ swings, the swinging member A ₁ can perform the same operation as the pressing portion 4b of the sliding body 4 being formed extremely accurately, and the detected electrical signal of the detector 12 can be rotated to either the left or the right. The torque detection device can be stably detected even at a time, and the electrical neutrality can be stabilized, and the reliability of the torque detection device can be significantly improved.

Next, since the contact portions 8 of the swinging member A ₁ operate while correcting the inaccurate formation state of the pressing portion 4b with respect to the slide body 4, the manufacture of the slide body 4 and the slide body 4 are performed. For mounting on the output shaft 2 etc., highly accurate operation can be performed without performing high-precision processing and assembly, the quality of the device can be improved, and the manufacturing cost can be reduced. You can

[Brief description of drawings]

FIG. 1A is a partially sectional side view showing an embodiment of the present invention, and FIG. 1B is a schematic view of an electric power steering using the present invention.

FIG. 2 is a vertical sectional side view of a main part of the present invention.

FIG. 3 is a schematic view of a mechanism showing a main part of the present invention.

FIG. 4 is a schematic view showing a main part of the present invention.

FIG. 5 is an exploded perspective view of essential parts of the present invention.

FIG. 6 is a plan view showing the operation of the present invention as seen from the detector side.

FIG. 7 is a schematic view showing a state of a sliding body and a swing member.

FIG. 8 is a plan view seen from the detector side, showing the operation when rotating in the opposite direction to FIGS. 6 and 7.

FIG. 9 is a schematic view showing a state of a sliding body and a swinging member when rotating in the opposite direction to FIGS. 6 and 7.

[Explanation of symbols]

1 ... Input shaft 2 ... output shaft 3 ... torsion bar 4 ... sliding body 4b ... pressing portions 6 annular members 8 ... contact portion A ₁ ... swing member 12 ... detector

Claims (1)

[Claims] 1. A diameter of a ring-shaped body, wherein a sliding body, which connects an input shaft and an output shaft with a torsion bar, and has a pressing portion formed on an outer peripheral portion thereof, is rotatable with the output shaft and slidable in an axial direction. Both contact portions of the swinging member that allows the annular body to swing about two contact portions formed at both ends in the direction are brought into contact with the pressing portion of the sliding body, and both contact portions on the other surface side of the annular body. A torque detecting device for an electric power steering, characterized in that one side of a position substantially orthogonal to a line connecting between is swingably supported, and the other side is in contact with a detector.