JPH0227201A - Position detecting sensor structure - Google Patents

Abstract

PURPOSE:To enable highly accurate detection of a change in relative position in a full range of relative displacements by arranging a magnetic detection element so as to move relatively non-contact in a magnetic circuit in a specified direction. CONSTITUTION:A magnetic detector 25 and a magnetic circuit 21 composes a first position detecting sensor 20 to detect relative positions of a steering gear device 4 and a tie rod 5 in a full range of relative displacements. Then, to upgrade a detection accuracy near a neutral position where especially a high accuracy is required in a full steering range of a wheel 6 with an aim to a higher running stability of an automobile, a second position detecting sensor 30 in addition to the sensor 20. The sensor 30 is made up of a magnetic detector 35 and a magnetic circuit 31 in the construction identical to the sensor 20. This enables detection of changes of relative displacements in a full range of the displacements while permitting detection of changes in relative position as for a certain fixed area at a higher accuracy than other areas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the structure of a position detection sensor that non-contact detects a change in the relative position of two members that undergo relative displacement within a predetermined range.

[Prior Art] Conventionally, as a position detection device for detecting a change in the relative position of two members that perform relative displacement, for example,
As shown in Publication No. 1-152121, a sliding contact is brought into contact with the surface of one of the grounded members, and a change in the potential of the sliding contact due to relative displacement of the one member with respect to the other is detected. Accordingly, a device that detects a change in the relative position of one member with respect to the other member is generally well known.

However, the contact type using sliding contacts as described above has a problem in that it is not sufficiently durable for long-term use, such as a decrease in detection accuracy due to wear of the sliding part.

Therefore, in order to solve the above problem by performing position detection without contact, for example, a magnetic detection element whose output value changes according to changes in the magnetic field is attached to one member, and a magnetic detection element is attached to the other member. , a magnetic circuit is provided in which the magnetic field changes along the direction of the relative displacement of the two members, and the magnetic detection element is arranged within this magnetic circuit so that it can move relatively without contact, and the two members are arranged relative to each other in the direction of relative displacement. When the displacement is performed, the magnetic sensing element moves relatively within the magnetic circuit, and by detecting a change in the magnetic field acting on the magnetic sensing element due to this movement, the relative relationship between the two members is detected. 2. Description of the Related Art Position detection sensors that detect changes in position are known.

That is, in the above-mentioned position detection sensor, as shown in FIG.
Permanent magnets 91b, 91b are sandwiched at both ends of 91a, 91a, respectively, so that the polarities are opposite to each other, and a magnetic circuit 91 is formed by these two permanent magnets 9th and the two plates 91a, In this magnetic circuit 91, there is a magnetic detection element 95 whose output value changes according to changes in the magnetic field.
The magnetic detection element 95 and the magnetic circuit 91 constitute a position detection sensor 90. The magnetic detection element 95 and the magnetic circuit 91 constitute a position detection sensor 90.

In the magnetic circuit 91, permanent magnets 9th, 9 at both ends
The magnetic flux density is high near th, and decreases as it approaches the center. The direction of the magnetic field is opposite across the center. Therefore, the characteristics of the magnetic field (magnetic flux density and direction of the magnetic field) change over the entire length of the magnetic circuit 91 in the longitudinal direction, and this magnetic circuit 9! The magnetic detection element 95, which moves in the longitudinal direction within the magnetic circuit 91, detects changes in the characteristics of the magnetic field that change in the direction of movement (the longitudinal direction of the magnetic circuit 9!), and detects the relative position of the self 95 with respect to the magnetic circuit 91. Changes can be detected.

Therefore, the magnetic circuit 91 is attached to one of the two members that perform relative displacement, and the magnetic detection element 9 is attached to the other.
5, it is possible to detect changes in the relative positions of these two members without contact.

[Problems to be Solved by the Invention] However, in the position detection sensor 90 as described above, the rate of change in magnetic flux density along the longitudinal direction within the magnetic circuit 91 (the amount of change in magnetic flux density per unit length) is Since it is constant,
The detection accuracy of the sensor 90 is constant over the entire length of the magnetic circuit 91, and it cannot respond to cases where highly accurate position detection is required in some areas. Furthermore, when the relative displacement between the two members increases and the required length of the magnetic circuit 91 increases, the rate of change in the magnetic flux density decreases, and the position detection accuracy of the sensor 90 decreases. .

For this reason, the amount of relative displacement between the two members mentioned above is relatively large, and it is necessary to perform position detection over the entire range of the relative displacement. There is a problem in that it cannot handle cases where position detection is required.

This invention was made in view of the above problems, and when detecting a change in the relative position of two members that perform relative displacement without contact, it detects a change in the relative position over the entire range of the relative displacement. In addition, the present invention aims to provide a position detection sensor structure that can provide higher detection accuracy in some predetermined areas that require high position detection accuracy than in other areas out of the above-mentioned entire range. purpose.

[Means for Solving the Problem] Therefore, the present invention includes a magnetic circuit whose magnetic field changes along a predetermined direction, a magnetic detection element whose output value changes according to the change of the magnetic field, and a magnetic detection element whose output value changes according to the change of the magnetic field. The magnetic detection element is configured to be able to relatively move in the predetermined direction within the magnetic circuit without contact, and the magnetic detection element is configured to be able to relatively move in the predetermined direction within the magnetic circuit in a non-contact manner. The magnetic circuit is attached so that the magnetic circuit substantially coincides with a predetermined direction, and the magnetic detection element is attached to the other side, and the magnetic circuit moves relatively in the predetermined direction within the magnetic circuit as the two members are displaced relative to each other. In a position detection sensor structure in which a detection element detects a change in the relative position of the two members by detecting a change in the magnetic field acting on the magnetic detection element, the relative displacement of the two members a first position detection sensor that detects a change in the relative position of the two members over the entire range; A second position detection sensor that detects changes with higher accuracy than the first position detection sensor is provided.

[Effects of the Invention] According to this invention, changes in the relative positions of the two members are detected over the entire range of relative displacement between the two members. In addition to the position detection sensor, the first sensor detects changes in the relative positions of the two members for a predetermined area of the entire range.
Since a second position detection sensor is provided that detects with higher precision than the position detection sensor, it is possible to detect changes in the relative position of the two members over the entire range of relative displacement between the two members, and For a certain predetermined area within the range, changes in the relative positions of the two members can be detected with higher accuracy than for the pond area.

In addition, by comparing the detection results of the two position detection sensors in the predetermined area where the first and second position detection sensors are installed, it is possible to detect when one of the position detection sensors has failed. can immediately detect the occurrence of this failure.

[Embodiment 1] Hereinafter, an embodiment in which the present invention is applied to a steering angle sensor for detecting the wheel steering angle of an automobile will be described in detail with reference to the accompanying drawings.

As shown in FIG. 7, the steering mechanism 10 for an automobile according to the present embodiment includes a steering wheel 1, and a steering system in which the rotation of the steering wheel 1 is inputted by sequentially valving a steering shaft 2 and an intermediate shaft 3. It is equipped with a gear device 4 and a tie rod 5 that steers left and right wheels 6,6 by the output of the gear device 4, and by rotating the steering wheel 1, the rack and the wheels are steered.
The tie rod 5 is connected in the vehicle width direction (
By displacing the tie rod 5 in the lateral direction, it is possible to change the direction of the left and right wheels 6, 6.

Rotation angle of the above steering wheel I (handle steering angle)
The transmission ratio of the turning angle θ (wheel steering angle) of the wheels 6.6 and 6.6 is set constant by the gear ratio of the steering gear device 4, etc. The angle θ can be controlled.

A steering angle sensor 11 for detecting the wheel steering angle θ is arranged in front of a boot 7 that covers a connecting portion between the steering gear device @4 and a tie rod 5 provided coaxially with the gear device 4. , an outer bracket 8 fixed to the tie rod 5 and an inner bracket 9 fixed to the steering gear device 4 fixed to the vehicle body, parallel to the steering gear device 4 and the tie rod 5. installed.

As will be described in detail later, the steering angle sensor 11 includes a hollow cylindrical cylinder 12 and a piston 13 provided so as to be able to reciprocate relative to the cylinder 12. The side end 12a (outside end) is fastened and fixed to the outside bracket 8, while the end 13a (inside end) on the piston 13 side is fastened and fixed to the vehicle body.

Therefore, the cylinder 12 and piston 13 are the steering wheel! The tie rod 5 performs a relative reciprocating sliding movement in accordance with the lateral displacement of the tie rod 5 accompanying the steering.

In addition, the mounting position of this steering angle sensor 11 is the position where this steering damper is installed in a vehicle that is provided with a steering damper for absorbing vibrations from the road surface in the vehicle width direction, and the above-mentioned cylinder! 2 and piston 13, those used in this steering damper can be used.

As shown in detail in FIGS. 1 and 2, the steering angle sensor 11 is inserted into a hollow cylindrical cylinder 12 via a bearing 14, and extends in the longitudinal direction of the cylinder 12. Inside the cylinder 12, a magnetic field is applied along the longitudinal direction in order to detect changes in the steering angle θ of the wheels 6.6. magnetic circuit 21 (second
(see figure) is attached.

As shown in detail in FIG. 4, the magnetic circuit 21 includes two plates 21a made of iron-based material, and these plates 21.
It is composed of permanent magnets 21b and 21b sandwiched near both ends of the two plates 2a and 21a, respectively.
1a are arranged in parallel with a predetermined interval, and the permanent magnets 21b and 21b are attached near both ends of these plates 21a and 2fa so that their polarities are opposite to each other.

In the magnetic circuit 21, permanent magnets 21b and 2 at both ends are
The magnetic flux density is high near 1b, the magnetic flux density is low as it approaches the center, and the direction of the magnetic field is opposite across the center. Therefore, the characteristics of the magnetic field (magnetic flux density and direction of the magnetic field) change with respect to the total length Ll in the longitudinal direction of the magnetic circuit 21 (the distance between the permanent magnets 21b at both ends).

The total length of the magnetic circuit 2I is set to a length sufficient to cover the entire relative displacement between the steering gear device 4 and the tie rod 5 in the steering mechanism 10 of the vehicle.

Both ends of the magnetic circuit 21 are coupled, for example, with rivets to one end of a magnetic circuit holder 22.22 holding the magnetic circuit 21, and the other end of the magnetic circuit holder 22.22 is
The magnetic circuit 21 is fixed to plugs 5.16 (see FIG. 1) attached to the left and right ends of the cylinder 12, respectively, and the magnetic circuit 21 is connected via these plugs 15.16 and the magnetic circuit holder 22.22. Then, the above cylinder 1
Fixed to 2.

On the other hand, at the tip of the piston 13, there are
As shown in detail in the figure, the magnetic circuit 2! plate material 21a
, 21a are fixed to two parallel guide plates 23 arranged perpendicularly to the guide plates 23.23, and the upper and lower ends of the guide plates 23.23 are fixed to the upper and lower guide plates 15.16, both ends of which are fixed to the plugs 15.16. Guide grooves 17a are recessed in each of the rails 17.17.

..., fitted into 17a, cylinder 12 and piston 13
and are relatively displaced, the guide plate 23.23 becomes
It can freely move within the cylinder 12 while being guided by the guide grooves 7a, . . . , 17a.

The guide plates 23.23 are integrally formed with extensions 23a, 23a extending toward the opposite side of the piston (right side in the figure), and a module mounting plate 24 is fixed to the upper surface of the extensions 23a, 23a. There is. The module mounting plate 2
An abbreviated arm portion 24a that falls downward and extends toward the inner wall of the cylinder 12 extends from approximately the center in the left-right direction of the cylinder 12.
The tip part 24b of a is connected to two plates 2 in the magnetic circuit 21.
A magnetic detection element 25, which is arranged parallel to 1a and whose output value changes according to changes in the magnetic field, is attached to the tip 24b. The magnetic detection element 25 and the magnetic circuit 21 provide a first position detection sensor 20 ( (hereinafter referred to as the first sensor).

On the other hand, a detection module 26 having a built-in integrated circuit, for example, is fastened and fixed to the upper surface of the module mounting plate 24 for detecting the output voltage from the magnetic detection element 25 and outputting a detection signal to the outside. The detection signal from the detection module 26 is transmitted to the outside via a harness 27 (see FIG. 1) that is wired through a long hole (not shown) drilled in the axial center of the piston 13. It is designed to be output to a control device (for example, an in-vehicle control unit).

In the above configuration, when the tie rod 5 is laterally displaced by steering the steering wheel 1 and the steering angle θ of the wheel 6 changes in accordance with the displacement of the tie rod 5,
Depending on the amount of displacement of the tie rod 5 with respect to the steering gear device 4, the cylinder 12 and piston 13 of the steering angle θ sensor 11 are relatively slidably displaced, and the magnetic Detection element 25
moves relatively in the longitudinal direction (horizontal direction) within the magnetic circuit 21 without contact. The magnetic detection element 25 is
detecting changes in the magnetic field of the magnetic circuit 21 that changes along the longitudinal direction, and changes in position relative to the magnetic circuit 21;
In other words, piston! 3 relative displacement with respect to cylinder 12 can be detected.

By the way, in this embodiment, in order to improve the running stability of the automobile, in order to improve the detection accuracy near the neutral position where particularly highly accurate steering angle detection is required among the entire steering range of the wheels 6, In addition to the first sensor 20, a second position detection sensor 30 (hereinafter referred to as a second sensor) that covers the vicinity of the neutral position is provided.

This second sensor 30 will be explained below.

As shown in FIGS. 1 and 2, the second sensor 30 is connected to the second sensor 30 mentioned above! It has substantially the same configuration as the sensor 20, and the magnetic circuit 31 (second magnetic circuit) of the second sensor 30 is connected to the magnetic circuit 21 (first magnetic circuit) of the first sensor 20 and the cylinder 12.
The magnetic circuit holders 32, 32 and left and right plugs 15 and 16 are fixed to the cylinder 12 through magnetic circuit holders 32, 32 and left and right plugs 15 and 16, respectively.

The second magnetic circuit 31, as shown in detail in FIG.
Two iron-based plates 3 arranged in parallel with a predetermined distance apart
1a, and two permanent magnets 31b which are sandwiched near both ends of the plates 31a, 31a so that the polarities are opposite to each other.
For example, due to space constraints, the permanent magnets atb and 3tb are installed in the cylinder 12 in such a way that the corresponding portion is offset toward the center of the cylinder 12.

The second magnetic circuit 31 is, for example, a permanent magnet 31b having the same magnetic field strength as that for the first magnetic circuit 21.

31b is used, and its total length (distance M between permanent magnets 31b, 31b) is set to 1/2 of the total length rl, I of the first magnetic circuit 2I, so that in the longitudinal direction , the rate of change of magnetic flux density is the first @chi circuit 2
It is twice as much as in case I.

On the other hand, as shown in detail in FIGS. 3 and 6, on the lower surface of the extensions 23a, 23a of the guide plate 23, 23 fixed to the tip of the piston 13, there is a module mounting plate 24 for the first sensor. A module mounting plate 34 (second module mounting plate) for a second sensor disposed opposite to the second module mounting plate 34 is fixed to the lower surface of the second module mounting plate 34. A detection module 36 (second detection module) for a second sensor similar to the detection module 26 (first detection module) in the sensor is fastened and fixed.

Further, from approximately the center in the left-right direction of the module mounting plate 34, an abbreviated arm portion 34a rises upward and extends toward the inner wall of the cylinder 12.
The tip portion 34b of the arm portion 34a is connected to the second magnetic circuit 3.
The plate members 3Ia and 31a are arranged in parallel between each other. The magnetic detection element 35 for the second sensor (second magnetic detection element) is attached to the tip portion 34b of the arm portion 34a,
As with the first sensor (first magnetic detection element 25), with the relative displacement between the cylinder 12 and the piston 13,
It is configured to move between the plates 31a, 31a of the second magnetic circuit 31 in a non-contact manner.

As described above, the second magnetic circuit 31 has twice the rate of change in magnetic flux density along the longitudinal direction as the first magnetic circuit 21, so the position detection accuracy is also twice as high.

That is, as shown in the graph of FIG. 8, the rate of change of the output voltage per unit length when the second magnetic detection element 35 moves within the second magnetic circuit 31 over its entire length (the straight line in FIG. The slope of C9) is the total length of the first magnetic detection element 25,
(=2L,) is twice the rate of change mentioned above (the slope of the straight line Q1 in Fig. 8) when moving in the first magnetic circuit 2I, and the error in the output voltage is 1/2. be.

Therefore, in the area where the second sensor 30 is installed, the detection accuracy can be twice as high as in other areas where the position is detected only by the first sensor 20. Furthermore, in the above region, both the first sensor 20 and the second sensor 30 can simultaneously detect a change in relative position, so by comparing the detection results of both 20. If a failure occurs in 20 or 30, this failure can be immediately detected.

Although the above embodiment (hereinafter referred to as the first embodiment) was applied to the steering angle sensor 11 that detects the wheel steering angle θ of an automobile, the present invention is not limited to the above steering angle sensor. Of course, the present invention can also be applied to other position detection devices that detect changes in the relative positions of two members that perform relative displacement.

Further, the first embodiment described above detects a change in the relative position between the two members 4 and 5 that perform relatively linear reciprocating motion, but the present invention detects a change in the relative position between the two members 4 and 5 that relatively rotate. It can also be applied to the case of detecting a change in relative position between two members in the rotational direction.

A second embodiment of the present invention will be described below.

As shown in FIG. 9, the position detection sensor 5 according to this embodiment
1, for the entire rotation range of the two members 52.53 that rotate relative to each other, both members 52.5 in the rotation direction
a first sensor 60 that detects a change in the relative position of No. 3;
A second sensor 70 covering a part of the entire rotation range is arranged vertically in parallel.

The magnetic circuit 61 (first magnetic circuit) of the first sensor 60 includes two parallel plates 61 made of iron-based material and formed in an arc shape.
a, and two permanent magnets 61b sandwiched between the ends of these plates 61a, 61a so that their polarities are opposite to each other.
The magnetic circuit 71 (second magnetic circuit) of the second sensor 70 also includes the second! Like the magnetic circuit 61, it is composed of two parallel arc-shaped plates 71a and two permanent magnets 71b, and the length of the arc of the second magnetic circuit 71 is the same as that of the first magnetic circuit 61. is set shorter than.

Therefore, the rate of change in magnetic flux density is higher in the second magnetic circuit 7I than in the first magnetic circuit 61, and the rate of change in magnetic flux density is higher in the second magnetic circuit 7I than in the first magnetic circuit 61.
0 can detect the position with higher accuracy than the first sensor 60. Further, the first magnetic circuit 61 and the second magnetic circuit 71 are fixed to one rotating member 52 via mounting members 54 and 55, respectively.

The magnetic detection elements 65 and 75 of the first sensor 60 and the second sensor 70 are attached to the mounting plate 56 fixed to the other rotating member 53 via detection modules 66 and 76, respectively. The modules 66 and 76 can output detection signals to the outside through harnesses 57 and 58, respectively. The magnetic detecting element 65 (first magnetic detecting element) of the first sensor 60 is placed between the plates 61a, 61a of the first magnetic circuit 61, and the magnetic detecting element 75 (second magnetic detecting element) of the second sensor 70.
are arranged between the plates 71a, 71a of the second magnetic circuit 71, respectively.

Therefore, when the two members 52 and 53 rotate relative to each other, the first magnetic detection element 65 and the second magnetic detection element 75 are moved into the first magnetic circuit 61 and the second magnetic circuit, respectively. 71, and a change in the relative position of the rotation direction of the two members 52, 53 can be detected.

In addition to the first sensor 60 that detects changes in the relative positions of the two members 52 and 53 over the entire rotation range, the first sensor 60 also detects changes in the relative positions of the two members 52 and 53 over the entire rotation range. Since the second sensor 70 that can detect the position with high accuracy is provided, the same effects as in the first embodiment can be achieved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view of a steering angle sensor according to a first embodiment of the present invention, FIG. 2 is an explanatory cross-sectional view taken along line A-A in FIG. 1,
3 is an explanatory cross-sectional view taken along line B-B in FIG. 1, FIG. 4 is an overall perspective view of the first magnetic circuit according to the first embodiment, and FIG.
The figure is an overall perspective view of the second magnetic circuit according to the first embodiment,
FIG. 6 is an exploded perspective view of the detection module and module mounting plate according to the first embodiment, FIG. 7 is a schematic perspective view of the steering mechanism of the automobile according to the first embodiment, and FIG.
A graph showing the output characteristics of the position detection sensor according to the example,
FIG. 9 is an overall perspective view of a position detection sensor according to a second embodiment, and FIG. 10 is a cross-sectional explanatory view of a conventional position detection sensor. 4... Steering gear device, 5... Tie rod,
11... Rudder angle sensor, 12... Cylinder, 13...
・Piston, 20.60...No. sensor, 21.61
...First magnetic circuit, 25.65...First magnetic detection element, 30°70...Second sensor, 31.71...Second magnetic circuit, 35.75...Second magnetism detection element.

Claims (1)

[Claims] (1) A magnetic circuit in which the magnetic field changes along a predetermined direction,
a magnetic detection element whose output value changes in accordance with changes in the magnetic field, and is configured such that the magnetic detection element can relatively move within the magnetic circuit in the predetermined direction without contact; The magnetic circuit is attached to one of the two members that perform relative displacement so that the direction of the relative displacement substantially coincides with the predetermined direction, and the magnetic detection element is attached to the other, and the two members The magnetic detection element, which moves relatively in a predetermined direction within the magnetic circuit in accordance with the relative displacement of the two members, detects the change in the magnetic field acting on the magnetic detection element, thereby determining the relative position of the two members. In a position detection sensor structure configured to detect changes, a first position detection sensor detects a change in the relative position of the two members over the entire range of relative displacement between the two members, and a part of the entire range. and a second position detection sensor that is disposed in a predetermined area of the area and detects a change in the relative position of the two members with higher precision than the first position detection sensor for the area. position detection sensor structure.