JP3064715B2 - Rotation angle sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle sensor for detecting a rotation angle of a shaft, and more particularly to a non-contact type rotation angle sensor using a ferromagnetic magnetoresistive element.

[0002]

2. Description of the Related Art Recently, with respect to a sensor for detecting a rotation angle or a rotation position, use of a magnetic sensor has attracted attention due to a demand for forming a non-contact mechanism or reducing inertia loss of a shaft. This magnetic sensor uses a magnetoresistive element, and is arranged such that the plate surface of the element faces a permanent magnet mounted on the tip of a shaft.

As the above-mentioned magnetoresistive element, a semiconductor magnetoresistive element and a ferromagnetic magnetoresistive element are known. The former utilizes the property that the electric resistance of a semiconductor changes in a magnetic field. The latter utilizes the property that the resistance of the ferromagnetic material in a magnetic field changes anisotropically depending on the angle between the magnetization direction and the current direction. This is called an anisotropic magnetoresistive effect and is distinguished from a negative magnetoresistive effect due to the magnitude of a magnetic field. That is, in a normal ferromagnetic material, the resistance becomes the maximum when the current and the magnetization direction become parallel due to the anisotropic magnetoresistance effect, and becomes the minimum when the current and the magnetization direction cross each other. In order to make use of this effect, a ferromagnetic metal thin film is linearly adhered to the surface of the substrate to form a ferromagnetic magnetoresistive element. For example, as described in JP-A-62-237302. There is known a rotational position detecting device in which a ferromagnetic magnetoresistive element is provided at one of an end face of a shaft and a position facing the end face, and a permanent magnet is provided at the other.

[0004]

With respect to the magnetic sensor described in the above publication, means for setting the position of the permanent magnet with respect to the ferromagnetic magnetoresistive element, that is, the gap between the two, to a predetermined value is not disclosed. In the case of manufacturing, the tolerance of the support portion of the substrate, the tolerance of the shaft length, the tolerance of the bearing length, the tolerance of the bearing support portion, etc. are superimposed, so the above gap is set to a predetermined value. It is extremely difficult to set, and a variation occurs. Such a variation in the gap between the ferromagnetic magnetoresistive element and the permanent magnet causes a variation in the magnetic flux density with respect to the former, and eventually causes a variation in the performance of the product.

[0005] For this reason, the present applicant has filed Japanese Patent Application No. Hei 4-296.
In the application of No. 333, a detection element having a ferromagnetic magnetoresistive element adhered to a plate surface of a substrate to improve the relative positional accuracy of the magnet member with respect to the ferromagnetic magnetoresistive element and secure stable output characteristics; A shaft that rotates relative to the detection element, a lid that is axially movably mounted to one end of the shaft and that is fixed to the shaft at a predetermined position, and between a lid and an end surface of the shaft. A magnet member for forming a magnetic field including at least a ferromagnetic magnetoresistive element, which is housed and brought into close contact with the lid, wherein the lid is attached to the shaft according to a predetermined gap between the magnet member and the ferromagnetic magnetoresistive element. A fixed rotation angle sensor has been proposed.

Further, as an embodiment of the application, a lever is caulked to the other end of the shaft, and a disc spring for urging the cover fixed to the shaft toward the detecting element is provided. In this method, when the rotation angle sensor vibrates, the shaft is urged toward the detecting element so as not to move in the axial direction. However, if the weight of the shaft and the lever is large, this is countered. For this reason, it is necessary to increase the urging force of the disc spring, and it is necessary to widen the joint portion in order to securely fix the lid so as not to drop off from the shaft, so that the structure around the shaft becomes large.
The structure around the shaft is described in JP-A-3-235.
No. 002, Japanese Unexamined Patent Publication No. 4-324302, and the like, the support structure of the magnet member is different from the structure of the above-mentioned application, and the lever is caulked to the shaft for easy assembly. is not.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-contact type rotation angle sensor having a shaft supporting structure capable of ensuring stable output characteristics, and at the same time reducing the size and weight.

[0008]

In order to achieve the above object, a rotation angle sensor according to the present invention comprises a detecting element having a ferromagnetic magnetoresistive element, a housing for supporting the detecting element, and a rotating element mounted on the housing. A shaft freely supporting and rotating relative to the detection element, a resin lever integrally formed at one end of the shaft, and moving axially with respect to the other end of the shaft A lid body movably mounted and fixed to the shaft at a predetermined position, and a magnet member housed between the lid body and the other end of the shaft to form a magnetic field including at least the ferromagnetic magnetoresistive element. And an elastic member interposed between the lid and the housing to urge the shaft in the direction of the detection element.

[0009]

In the rotation angle sensor having the above configuration,
A lever is integrally formed with resin at one end of the shaft. After the magnet member is accommodated between the other end of the shaft and the lid, the lid is fixed to the shaft at a predetermined position, and an elastic member is interposed between the lid and the housing. , The shaft is urged toward the detecting element.
Accordingly, the shaft is appropriately supported by the housing, and the fixed position of the magnet member with respect to the ferromagnetic magnetoresistive element is appropriately adjusted, and the relative position accuracy is improved. Thus, when the lever is driven, the shaft rotates,
The magnet member rotates relative to the detection element. According to this relative rotation, the magnetic field of the parallel magnetic flux including the ferromagnetic magnetoresistive element of the detecting element changes, so that the resistance value changes,
A signal corresponding to the rotation of the shaft is output from the detection element.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a rotation angle sensor according to the present invention is applied to a throttle position sensor of an internal combustion engine will be described below with reference to the drawings. In an internal combustion engine equipped with an electronic control fuel injection device, a throttle position sensor is mounted, and its output signal is used for fuel injection control and the like. The throttle position sensor is connected to a throttle valve shaft, and normally outputs a throttle opening signal that changes according to a throttle valve opening (hereinafter, referred to as a throttle opening) and an idle signal that turns on and off depending on whether the engine is in an idle range or an output range. Is done. A non-contact type rotation angle sensor is used as the throttle position sensor.

FIG. 1 shows a throttle position sensor 1 according to an embodiment of the present invention. The throttle position sensor 1 is mounted on a throttle body (not shown), and a shaft 2 is supported so as to rotate in conjunction with a throttle shaft (not shown). I have.
That is, the throttle position sensor 1 includes a synthetic resin housing 3 having two adjacent concave portions 3a and 3b, and the shaft 2 is rotatably provided via a bearing 4 in a partition wall 3c between these concave portions 3a and 3b. Supported. The bearing 4 is formed integrally with the housing 3 and is fixed at a predetermined position.
Are arranged.

A lever 5 is integrally formed at one end of the shaft 2. That is, the current groove 2a is formed at one end of the shaft 2, and the lever 5 is integrally formed of a synthetic resin so as to surround the groove 2a. This lever 5 is housed in one concave portion 3a of the housing 3,
It is connected to a throttle shaft (not shown). A return spring 6 is interposed between the housing 3 and the lever 5, and the lever 5 is biased in a predetermined initial position direction. Therefore, with the opening operation of the throttle valve (not shown), the lever 5 linked to the throttle shaft is driven against the urging force of the return spring 6, and the shaft 2 rotates. At the other end of the shaft 2, a rotor magnet 20, which is a magnet member according to the present invention, is mounted. In addition, this rotor magnet 20
Will be described later.

A magnetic sensor 10, which is a detecting element of the present invention, is disposed in the other concave portion 3b of the housing 3 at a position facing the rotor magnet 20. The magnetic sensor 10 has a ferromagnetic magnetoresistive element (hereinafter simply referred to as a magnetoresistive element) made of a strip-shaped thin film ferromagnetic alloy such as a Ni-Co alloy on one surface (a lower surface in FIG. 1) of a rectangular element substrate. ) Is attached. This magnetoresistive element has a property that its resistance value change rate saturates at a predetermined magnetic flux density, for example, 10 mT, and a strip-shaped thin-film ferromagnetic alloy is bent to increase the resistance. It is formed in such a pattern shape. Further, a bias magnet 11 shown in FIG. 1 is fixed to a predetermined position on the other surface (the upper surface in FIG. 1) of the magnetic sensor 10 by an adhesive.

The magnetic sensor 10 configured as described above
1 is mounted on a hybrid IC board 30 (hereinafter simply referred to as an IC board 30) as shown in FIG. 1, and a plurality of terminals 7 are connected to its end. Terminal 7
Is buried in the housing 3 and extends sideways to form a connector 8 integrally with the housing 3. IC
The substrate 30 is accommodated in the concave portion 3b of the housing 3 and supported by the support surface 3d. The concave portion 3b is hermetically sealed by a synthetic resin cover 9 via a rubber seal member 19. The magnetic sensor 10 is attached to one surface of the IC substrate 30, but the entire IC substrate 30 may be molded with a synthetic resin. Thus, the magnetoresistive element includes the rotor magnet 20 and the bias magnet 11.
Where the combined magnetic field of the two magnets is applied.
Note that a detection circuit element for processing the output signal of the magnetic sensor 10 and the like are mounted on the IC board 30, but the description is omitted because it is well known.

The rotor magnet 20 is mounted on the shaft 2 as described below, and is configured to rotate integrally with the shaft 2. That is, a concave portion 2 b is formed in the other end of the shaft 2 in the axial direction, and after the return spring 6 is attached to the lever 5 formed at one end of the shaft 2, The collar 5 is inserted and supported in a state where the lever 5 is in contact with the collar 24. With the shaft 2 supported in this manner, the recess 2
The compression spring 21 is accommodated in b, and the rotor magnet 20 is accommodated thereon. Further, an annular disc spring 23 as an elastic member according to the present invention is fitted around the shaft 2 and seats on the bearing 4. After the anaerobic adhesive is applied to the top of the rotor magnet 20, the bottomed cylindrical lid 22 is pressed into the shaft 2. As a result, the rotor magnet 20 is pressed against the bottom surface of the lid 22 by the compression spring 21, and is firmly adhered to the lid 22.

In this case, a collar 24 is mounted around the bearing 4 fixed to the housing 3, and a disc spring 23 is interposed between the lid 22 and the bearing 4. The press-fitting restricts the shaft 2 from moving in the axial direction with respect to the housing 3 via the lever 5 and the collar 24, and the disc spring 23 causes the bearing 4 and thus the housing 3 to move in the direction of the magnetic sensor 10 (FIG. 1). Above).

Thus, the IC substrate 30 is placed on the housing via a shim plate (not shown) of a predetermined thickness until the top surface of the lid 22 is flush with the support surface 3d, that is, the IC substrate 30 is mounted on the housing. 3 until it comes into contact with the support surface 3d, and press-fits the lid 22 into the shaft 2 so that the top surface of the lid 22 and the IC
The lid 22 is fixed to the shaft 2 at a position where the gap with the lower surface of the substrate 30 has a value equal to the predetermined thickness of the shim plate.
At this time, for example, even if the dimensions of the bearing 2 and the like vary, they are absorbed by the compression spring 21 so that the lid 22
Between the IC and the IC substrate 30, and thus the rotor magnet 2
The gap between 0 and the magnetoresistive element is kept at a predetermined value.

As described above, according to the present embodiment, the lid 22 can be disposed so as to face the IC substrate 30 with a predetermined gap without requiring a special jig, and A predetermined gap is maintained by the spring 23.
At this time, the urging force of the disc spring 23 may be smaller than before because the lever 5 is lighter than before, so that the gap between the cover 22 and the bearing 4 can be reduced, and The joint between the shaft 2 and the shaft 2 can be reduced. The lid 22 may be fixed to the shaft 2 by screwing instead of press fitting. Further, the rotor magnet 20 may be bonded to the bottom of the lid 22 with an adhesive in advance without providing the compression spring 21.

In the throttle position sensor 1 of this embodiment having the above-described structure, the lever 5 shown in FIG.
Rotates in the bearing 4. As the shaft 2 rotates, the magnetic field generated by the rotor magnet 20 also rotates, and the direction of the magnetic field of the parallel magnetic flux including the magnetic field changes with respect to the magnetoresistive element.
That is, the direction of the combined magnetic field of the magnetic field of the rotor magnet 20 and the bias magnetic field of the bias magnet 11 changes.
Thus, the resistance value of the magnetoresistive element changes due to the anisotropic magnetoresistance effect, a signal corresponding to the rotation of the shaft 2 is output from the magnetic sensor 10, and the output characteristic of the magnetic sensor 10 with respect to the rotation angle of the shaft 2 is , Resulting in characteristics having a wide range of linearity.

As described above, according to this embodiment, since the lever 5 is formed integrally with the shaft 2 by a synthetic resin, it is lightweight and does not need to be assembled. And lid 2
A disc spring 23 is interposed between the magnetic sensor 1 and the bearing 4.
Since the shaft 2 is urged in the zero direction, the shaft 2 can be appropriately supported at a predetermined position with respect to the housing 3.
In addition, since the fixed position of the lid 22 with respect to the shaft 2 is adjusted according to a predetermined gap between the rotor magnet 20 and the magnetic sensor 10, an error caused by a change in the relative position of the rotor magnet 20 with respect to the magnetic sensor 10 is generated. Is suppressed to a small value, and desired output characteristics can be obtained.

FIG. 3 shows another embodiment of the present invention.
In the above-described embodiment, the shaft 2 and the lever 5 are formed as separate members, but these are integrally formed of a synthetic resin to form a single rotating member 50. Other configurations are the same as those of the above-described embodiment, and thus the same reference numerals are assigned to the main components, and the description is omitted. Thus, according to this embodiment, not only the lever but also the shaft is made of synthetic resin, so that the weight is further reduced. This also allows the disc spring 23
Can be further reduced, the gap between the lid 22 and the bearing 4 can be reduced, and the joint between the lid 22 and the shaft 2 can be reduced, so that further downsizing can be achieved. .

[0022]

Since the present invention is configured as described above, the following effects can be obtained. That is, in the rotation angle sensor of the present invention, a lever is integrally formed at one end of the shaft with resin, and after the magnet member is housed between the other end of the shaft and the lid, the lid is Since the body is fixed to the shaft at a predetermined position, an elastic member is interposed between the lid and the housing, and the shaft is configured to be urged in the direction of the detection element. Changes in output characteristics due to fluctuations in
Stable output characteristics can be obtained. Moreover, the lever is lightweight, the shaft can be appropriately supported on the housing by the elastic member having a small urging force, and the joint between the lid and the shaft can be reduced. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a throttle position sensor according to an embodiment of a rotation angle sensor of the present invention.

FIG. 2 is an enlarged sectional view of a tip portion of a shaft according to an embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a throttle position sensor according to another embodiment of the rotation angle sensor of the present invention.

[Explanation of symbols]

 Reference Signs List 2 shaft 3 housing 4 bearing 5 lever 6 return spring 10 magnetic sensor (detection element) 11 bias magnet 20 rotor magnet (magnet member) 21 compression spring 22 lid 23 disc spring (elastic member) 30 hybrid IC substrate

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01B ⁷ /00-7/34 G01D 5/00-5/252 G01D 5/39-5/62

Claims (1)

(57) [Claims] A detecting element having a ferromagnetic magneto-resistive element; a housing supporting the detecting element; a shaft rotatably supported by the housing and rotating relative to the detecting element; A resin lever integrally formed at one end of the shaft, a lid movably mounted in the axial direction with respect to the other end of the shaft, and fixed to the shaft at a predetermined position; A magnet member housed between the other end of the shaft and forming a magnetic field including at least the ferromagnetic magnetoresistive element; and a shaft interposed between the lid and the housing, the shaft being connected to the detection element. A rotation angle sensor comprising: an elastic member that urges in a direction.