JPH11132707A - Rotation angle sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of distortion of sensor characteristics caused by relative and positional deviation of members which constitute a closed magnetic passage in a rotation angle sensor of closed magnetic passage type. SOLUTION: A throttle sensor 30 is provided with a case 31, a magnetism detection part 320 having a substrate 321 and a hall element 322, and a magnetic passage constituent body 35. The magnetic passage constituent body 35 consists of two split magnetic passage constituent parts 360, 370. A first magnetic passage constituent part 360 is fixed onto the valve shaft 21 of a throttle valve 20, and a second magnetic passage constituent part 370 is fixed onto the case 31. The hall element 322 is fixed onto the substrate 321 so that it is positioned between each of pole faces 363 and 373 of a movable magnet 362 of the first magnetic passage constituent part 360 and a fixed magnet 372 of the second magnetic passage constituent part 370. The pole face 363 of the movable magnet 362 is a spiral inclined face tilted with respect to the axial line of the valve shaft 21, and the pole face 373 of the fixed magnet 372 is a vertical face vertical to the axial line.

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 rotary shaft, and more particularly to a rotation angle sensor suitable as a throttle sensor for detecting an opening of a throttle valve in an internal combustion engine.

[0002]

2. Description of the Related Art As a rotation angle sensor used for a throttle sensor or the like, for example, a "throttle sensor" described in Japanese Patent Application Laid-Open No. 2-130403 is known.
As shown in FIG. 19, this throttle sensor 100
A plate 102 fixed to a rotary shaft 101 of a throttle valve (not shown), an arc-shaped permanent magnet 103 fixed to a side surface of the plate 102, a yoke 104 fixed to a side surface of the permanent magnet 103, and a yoke 104. It comprises a Hall element 105 provided opposite to the inclined surface.

In this throttle sensor 100, the rotating shaft 1
01, the inclined surface of the yoke 104 and the Hall element 1
05, the magnetic flux density passing through the Hall element 105 changes. Therefore, the rotation angle of the rotating shaft 101, that is, the opening of a throttle valve (not shown) can be detected from the magnitude of the magnetic flux density.

However, this throttle sensor 10
0 is an open magnetic path type sensor in which most of the magnetic flux B generated from the permanent magnet 103 passes through the space, and thus is susceptible to an external magnetic field generated by, for example, geomagnetism or buried electric wires. There is a problem that it is difficult to improve accuracy.

In order to reduce the influence of the external magnetic field, a closed magnetic circuit type sensor such as a "rotational position sensor" described in Japanese Patent Application Laid-Open No. Hei 7-260412 is used. Can be considered.

As shown in FIG. 20, the rotational position sensor 200 includes a magnet structure (magnetic path structure) 201 and a Hall effect device 205. The magnetic path constituting member 201 includes a magnetically permeable pole piece 202 having a C-shaped cross section which rotates integrally with a rotating shaft (not shown) (the axis of which is indicated by “C”) and a portion facing each other in the magnetically permeable pole piece 202. A pair of magnets 20 each of which is fixed and each of its opposing surfaces (magnetic pole surfaces) is formed obliquely.
3,204. The Hall effect device 205 is disposed between the magnets 203 and 204 at a predetermined distance from each of the opposing surfaces.

In the rotational position sensor 200, the magnetic path constituting member 201 rotates together with the rotating shaft, and the Hall effect device 20
Since the magnetic flux density passing through 5 changes, the rotation angle of the rotating shaft can be detected from the magnitude of the magnetic flux density.
Further, in this rotation position sensor 200, each magnet 2
Most of the magnetic flux generated from the magnetic pole pieces
2, it is less susceptible to an external magnetic field than the above-described open-magnetic-path type sensor, and the detection accuracy can be improved.

[0008]

By the way, in order to obtain desired sensor characteristics in the rotational position sensor 200 as described above, the distance L between the magnets 203 and 204 shown in FIG. 20) so that a predetermined relationship is satisfied between the magnets 203 and 204.
May be set.

However, the rotational position sensor 200
In this case, even if the shapes of the magnets 203 and 204 are appropriately set, each magnet 2
There has been a problem that the sensor characteristics are distorted when the mounting positions of 03 and 204 are shifted in the rotation direction of the rotating shaft.

For example, as shown by the solid line in FIG. 22, when the distance L is set so that the sensor output V changes linearly with the change in the rotation angle θ, the magnet 2 as described above is used.
When the position shift of 03 or 204 occurs, the sensor output V changes as shown by the broken line in FIG.

In general, when the rate of change of the sensor output V with respect to the rotation angle θ changes while maintaining the linearity as shown by the one-dot chain line in FIG. 22, or when the linearity is changed as shown by the two-dot chain line in FIG. When the sensor output V is offset while being maintained, the sensor characteristic can be easily corrected to a desired characteristic by multiplying or adding the correction coefficient to the sensor output V.

However, when the sensor characteristic is distorted, it is usually difficult to correct the distortion, and in the case of a conventional closed magnetic circuit type sensor, the detection accuracy of the sensor deteriorates due to such distortion of the sensor characteristic. There was a fear.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a closed-magnetic-path-type rotation angle sensor that is capable of generating distortion in sensor characteristics due to relative displacement of members constituting a closed-magnetic path. It is to control.

[0014]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a magnetic path structure including a magnetic flux generating portion and a pair of opposing portions opposing each other with a magnetic detector interposed therebetween. Construct a closed magnetic path of magnetic flux passing through the magnetic detector, change the magnetic flux density at the same position by changing the distance between the opposing parts at the position of the magnetic detector by causing the opposing part to respond to the rotation of the rotating shaft, In the rotation angle sensor configured to detect the rotation angle of the rotating shaft from the magnitude of the magnetic flux density, one of the facing surfaces of each facing portion is formed as a helical inclined surface inclined with respect to the axis of the rotating shaft, and Is a vertical plane perpendicular to the coaxial line.

In the above configuration, one of the opposing surfaces of the opposing portions is formed as a helical inclined surface inclined with respect to the axis of the rotating shaft. The interval between the parts changes, and the magnitude of the magnetic flux density at the same position changes. The magnetic detector outputs a detection signal corresponding to the rotation angle of the rotating shaft based on the magnitude of the magnetic flux density.

Further, according to the above configuration, the other of the opposing surfaces of the opposing portions is a vertical surface perpendicular to the axis of the rotating shaft, so that the position of each opposing portion is set in the circumferential direction of the rotating shaft. Even in the case of relative displacement, the predetermined relationship set between the angle around the rotation axis and the distance between the opposing surfaces does not change.

According to the second aspect of the present invention, in the rotation angle sensor according to the first aspect, the distance L (θ) between the opposing surfaces in the axial direction of the rotation axis is a function of the angle θ about the rotation axis: L (Θ) = √ (αθ + β) + γ (α,
(β and γ are constants).

According to the above construction, in addition to the function of the first aspect, the magnitude of the magnetic flux density between the opposed portions changes linearly with the change of the angle θ about the rotation axis. , And a signal that changes linearly with the change in the rotation angle of the rotation shaft is output from the magnetic detection body.

According to a third aspect of the present invention, in the rotation angle sensor according to the first or second aspect, the magnetic path constituting member includes a plurality of magnetic path constituting portions, and a magnetic flux generating portion is provided between each magnetic path constituting portion. The magnetic path component is integrally formed by molding a plastic magnet.

For example, unlike the above-described configuration, when each magnetic path component is fixed using an adhesive, when the joining surface of each magnetic path component is not processed into a shape that can be in close contact, Sufficient adhesive strength cannot be ensured, and the structural strength of the magnetic path construct may be reduced.

In this regard, according to the configuration of the present invention, even when the joint surfaces of the magnetic path components are not formed into a shape that allows close contact as described above, each magnetic path component is reliably formed by the plastic magnet. Integrated into

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 shows a first embodiment in which the present invention is applied to a throttle sensor of a vehicle engine.
This will be described with reference to FIGS.

FIG. 1 shows a cross section of a throttle body 10 constituting a part of an engine intake system, and FIG. 2 shows a main part of a throttle sensor 30 provided in the throttle body 10.

A part of an intake passage 11 for supplying intake air to an engine (not shown) is formed in the throttle body 10, and a throttle valve 20 for adjusting an intake air amount is provided in the intake passage 11. . The valve shaft 21 of the throttle valve 20 is rotatably supported at both ends by a pair of bearings (not shown) with respect to the throttle body 10.

The driven gear 12 is fixed to one end of the valve shaft 21 (the left end in FIGS. 1 and 2). The driven gear 12 is connected to a driving gear 13a of a throttle motor 13 attached to the throttle body 10 by a reduction gear 1a.
4 for driving connection. These drive gears 13
a, the driven gear 12 and the reduction gear 14 are all made of a metal material. When the valve shaft 21 is driven to rotate by the throttle motor 13, the opening of the throttle valve 20 (throttle opening) is changed.

The throttle sensor 30 is connected to the valve shaft 2
It has a function of detecting the rotation angle of 1, that is, the throttle opening. The throttle sensor 30 is made of a synthetic resin case 3 attached to the side wall of the throttle body 10.
1. a magnetic detection unit 320 attached to the case 31;
And a magnetic path constituting member 35.

The magnetic path constructing body 35 is composed of a first magnetic path forming section 360 that rotates integrally with the valve shaft 21 and a second magnetic path forming section 370 fixed to the case 31. Hereinafter, each of these magnetic path components 360 and 370 will be described.

The first magnetic path constituting portion 360 includes a movable core 361 fixed at one end of the valve shaft 21 adjacent to the driven gear 12, and a movable magnet fixed to the movable core 361 as a magnetic flux generating portion. 362.

The movable core 361 is made of a material having a high magnetic permeability (for example,
As shown in FIG. 3, it has a substantially fan-shaped plate portion 361a and a cylindrical portion 361b integrally formed with the plate portion 361a. This cylindrical portion 36
1b is fitted and fixed externally to one end of the valve shaft 21.

The movable magnet 362 has a semicircular shape,
It is located concentrically with the cylindrical portion 361b and fixed to the outer peripheral portion of the plate portion 361a. This movable magnet 362 is shown in FIG.
As shown in FIG. 4, the valve shaft 21 has a magnetic pole surface 363 that extends in a helical manner inclining with respect to the direction of the axis of the valve shaft 21 (dashed line C in FIG. 4).

On the other hand, the second magnetic path constituting portion 370 is the case 3
1 and a fixed magnet 3 serving as an annular magnetic flux generator fixed to the fixed core 371.
72.

The fixed core 371 is similar to the movable core 361.
As shown in FIGS. 1 and 2, it is formed of a high magnetic permeability material and has a disk portion 371a and a columnar portion 371b formed at the center of the disk portion 371a. Fixed core 371
Is fixed to the case 31 so that the cylindrical portion 371b is located coaxially with the valve shaft 21.

The fixed magnet 372 is positioned concentrically with the disk portion 371a, and is fixed to the disk portion 371a so as to surround the column portion 371b. This fixed magnet 372
Unlike the movable magnet 362, has a magnetic pole surface 373 perpendicular to the axis of the valve shaft 21.

As described above, the first magnetic path component 360 is fixed to the valve shaft 21 and the second magnetic path component 370 is fixed to the case 31, so that each magnet 362,
372 is arranged so that the magnetic pole surfaces 363 and 373 face each other at a predetermined interval. Further, as the valve shaft 21 rotates, the relative positional relationship between the movable magnet 362 and the fixed magnet 372 in the circumferential direction of the valve shaft 21 changes, but since the fixed magnet 372 has an annular shape, each magnet 362 , 372 each pole face 36
3, 373 are always in a facing state.

The throttle sensor 30 in the present embodiment
Then, as shown by a chain line B in FIG.
A closed magnetic path is formed by the magnetic flux generated at 372. Therefore, the magnetic flux is applied to each of the magnets 362 and 372 and each of the cores 361 and 371 except for the gap between the two magnets 362 and 372.
Has passed through the interior of This closed magnetic circuit is the valve shaft 2
1, a central magnetic path including a cylindrical portion 361b of the movable core 361, and a cylindrical portion 371b of the fixed core 371, a plate portion 361a of the movable core 361, a disk portion 371a of the fixed core 371, and each magnet 362. , 372. The cross-sectional area of the magnetic flux passing through the outer peripheral magnetic path is larger than the cross-sectional area of the magnetic flux passing through the central magnetic path.

Next, the magnetic detector 320 will be described.
As shown in FIG. 1 and FIG.
And a Hall element 322 as a magnetic detector. The Hall element 322 is sandwiched between the magnets 362 and 372, and the magnets 362 and 372
Are fixed on the substrate 321 at a predetermined distance from the magnetic pole surfaces 363 and 373. This Hall element 32
The gap between the magnetic pole surfaces 363 and 373 at the position 2 is a detection gap 323 in the throttle sensor 30. The substrate 321 has a signal processing unit (not shown) including a drive circuit for driving the Hall element 322, a temperature compensation circuit, a signal conversion circuit (all not shown), and the like.
Are arranged.

An output signal corresponding to the throttle opening is output from the throttle sensor 30 as follows. The valve shaft 21 is controlled by the throttle motor 13.
Is driven to rotate, the movable magnet 362 rotates together with the valve shaft 21, and the length of the detection gap 323 changes. Then, in accordance with this change, the detection gap 3
The magnitude of the magnetic flux density at 23 changes. The Hall element 322 is electrically driven by the drive circuit, and generates a Hall voltage that changes linearly according to the magnitude of the magnetic flux density in the detection gap 323. An output signal corresponding to the throttle opening is generated from the signal processing unit based on the Hall voltage.

Here, in this embodiment, the detection gap 3
The length (hereinafter referred to as “gap length”) L is a function of the rotation angle of the valve shaft 21, that is, a function of the throttle opening θ (= L (θ)). The magnetic flux density B (θ) at H.323 changes linearly with a change in the throttle opening θ.

The procedure for setting the gap length L (θ) will be described below. First, as shown by the solid line in FIG. 5, the gap length L (θ) changes linearly with the change of the throttle opening θ based on the following equation (1).
(Θ) is set.

[0040]

(Equation 1) In the above equation (1), Lmax is a gap length L (θ) corresponding to the maximum value θmax of the throttle opening θ, and Lmin
Is the gap length L (θ) corresponding to the minimum value θmin of the throttle opening θ.

Next, the throttle opening θ and the magnetic flux density B when the gap length L (θ) is set as described above.
The relationship with (θ) is determined by experiment. FIG. 6 shows the results of this experiment. As shown by the solid line in the figure, it can be seen that the magnetic flux density B (θ) increases quadratically as the throttle opening θ increases. Therefore, this magnetic flux density B (θ) is approximated as a quadratic function of the throttle opening θ as shown in the following equation (2). By using the quadratic function in this way, the magnetic flux density B (θ) can be very accurately approximated as a function of the throttle opening θ.

[0042]

(Equation 2) In the above equation (2), a, b, and c are constants determined from the relationship between the throttle opening θ and the magnetic flux density B (θ) shown in FIG.

From the above equations (1) and (2), the gap length L
The relationship between (θ) and the magnetic flux density B (θ) is obtained as the following equation (3).

[0044]

(Equation 3) In the above equation, p and q are constants determined by the following equations (4) and (5).

[0045]

(Equation 4) Next, assuming that the magnetic flux density B (θ) changes linearly with the change in the throttle opening θ as shown by the dashed line in FIG. Equation (6) can be expressed as a linear function of

[0046]

(Equation 5) In the above equation (6), r and s are the following equations (7) and (8), respectively.
Is a constant determined by

[0047]

(Equation 6) In the above equations (7) and (8), Bmax is the magnetic flux density B corresponding to the maximum value θmax of the throttle opening θ.
(Θ), and Bmin is the minimum value θmi of the throttle opening θ.
The magnetic flux density B (θ) corresponding to n.

In order for the magnetic flux density B (θ) to change linearly with the change in the throttle opening θ, the following equation (9) derived from the above equations (3) and (6) is required. Must be satisfied.

[0049]

(Equation 7) Therefore, the gap length L (θ) in this case can be expressed as the following equation (10) based on the equation (9).

[0050]

(Equation 8) In the above equation (10), α, β, γ are expressed by the following equations (11) to
This is a constant determined by (13).

[0051]

(Equation 9) The throttle opening θ and the gap length L based on the equation (10)
The relationship with (θ) is shown by a dashed line in FIG. By setting the gap length L (θ) so as to satisfy this relationship,
The magnetic flux density B (θ) in the detection gap 323 can be changed linearly with the change in the throttle opening θ. In the present embodiment, the length of the movable magnet 362 in the axial direction of the valve shaft 21 is
The gap length L (θ) is set so as to satisfy Expression (10) by appropriately setting the gap length along the circumferential direction. Then, as described above, the detection gap 3
23, the magnetic flux density B (θ) changes linearly with the change in the throttle opening θ, and as shown by a solid line in FIG. As a result, an output signal V that changes linearly is output.

As described above, according to the present embodiment, since the linearity between the throttle opening θ and the output signal V is ensured, the predetermined value is simply determined for the output signal V as in the following equation (14). The throttle opening .theta. Can be obtained by an operation simply multiplying by the coefficient k.

[0053]

(Equation 10) For example, unlike the present embodiment, a throttle sensor whose output signal V does not linearly change with respect to the throttle opening θ is output to an electronic control unit (not shown; abbreviated as “ECU” hereinafter). Output signal V to the throttle opening θ
Of the ECU so that it changes linearly with changes in
It needs to be converted by U. Therefore, in such a throttle sensor, a function map for signal conversion must be obtained in advance and stored in the memory of the ECU. Further, the conversion of the output signal V must always be performed with reference to the function map, and an increase in the load on the CPU is inevitable.

In this respect, according to the present embodiment, the function map for signal conversion as described above is not required, so that the configuration of the memory can be simplified, and the increase in the load on the CPU due to the signal conversion can be avoided. it can.

Further, in this embodiment, each of the magnets 362, 3
The movable magnet 3 of the 72 facing magnetic pole surfaces 363 and 373
Although the magnetic pole surface 363 of 62 is inclined with respect to the axis of the valve shaft 21, the magnetic pole surface 373 of the fixed magnet 372 is set to be perpendicular to the coaxial line. Both magnets 362, 37
Even when the relative positions of the two shift, the linearity between the output signal V and the throttle opening θ is not lost, and the sensor characteristics are not distorted. That is, according to the present embodiment, even if such a displacement occurs, the output signal V is offset as shown by the one-dot chain line or the two-dot chain line in FIG. , The linearity of the output signal V is maintained.

For the offset of the output signal V, for example, the minimum value Vmin of the output signal V corresponding to the minimum value θmin of the throttle opening θ is stored in advance, and when the throttle opening θ becomes the minimum value θmin. The deviation (ΔV, −ΔV) between the actual output signal V and the minimum value Vmin is obtained, and the deviation can be easily corrected by subtracting the deviation from the output signal V over all the throttle openings θ. it can.

As described above, according to the present embodiment, it is possible to prevent the sensor characteristics from being distorted due to the misalignment of the magnets 362 and 372 in the circumferential direction of the valve shaft 21. Precise throttle opening θ
Can be detected.

Further, in the configuration according to the present embodiment, the fixed magnet 372 and the movable magnet 362 as the magnetic flux generating section are arranged on the outer peripheral magnetic path having a larger cross-sectional area than the central magnetic path. The configuration is effective in expanding the dynamic range of the sensor 30.

For example, unlike this embodiment, each magnet 36
2 and 372 are formed of a material having high magnetic permeability in the same manner as the cores 361 and 371, and a portion corresponding to the cylindrical portion 361b of the movable core 361 is used as a movable magnet, and the fixed core 371 is used.
A configuration in which a portion corresponding to the cylindrical portion 371b is replaced with a fixed magnet, that is, a configuration in which each magnet is arranged in the center magnetic path, similarly to the configuration according to the present embodiment,
A closed magnetic circuit can be configured. However, in such a configuration, since the magnetic flux generated from each magnet is dispersed when passing from the center magnetic path to the outer peripheral magnetic path having a large cross-sectional area, the magnetic flux density in the detection gap 323 is relatively low. Will be small.

In this regard, according to the present embodiment, each magnet 36
The magnetic flux generated in the detection gap 323 can be relatively increased because the magnetic flux generated from the second and second 372 is not dispersed as described above. Therefore,
The variable range of the gap length L of the detection gap 323 can be set large, and the amount of change ΔB of the magnetic flux density B (θ) when the throttle opening θ changes from the minimum value θmin to the maximum value θmax. By increasing (θ), the dynamic range of the throttle sensor 30 can be expanded.

[Second Embodiment] Next, a second embodiment according to the present invention will be described.
This embodiment will be described focusing on the differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the first embodiment, the first magnetic path constituting portion 360 is fixed to one end of the valve shaft 21 and
Similarly, a throttle motor 13 is drivingly connected to one end. On the other hand, in the present embodiment, the throttle motor 13 is driven to the other end of the valve shaft 21, that is, the end opposite to the end where the first magnetic path constituting portion 360 is fixed in the valve shaft 21. The difference from the first embodiment is that they are connected. Further, the magnets 362 and 372 are
The second embodiment differs from the first embodiment in that the yokes 364 and 374 are fixed to the first and second embodiments, respectively.

As shown in FIG. 8, in this embodiment, a driven gear 12 is fixed to the other end of the valve shaft 21, and the driven gear 12 is connected to a driving gear 13 a of a throttle motor 13 via a reduction gear 14. Drive-coupled.

Further, as shown in FIG.
A movable yoke 364 having a semicircular arc shape is fixed on the magnetic pole surface 363 so as to cover the entire magnetic pole surface 363. Similarly, the annular fixed yoke 37 is formed on the magnetic pole surface 373 of the fixed magnet 372 so as to cover the entire magnetic pole surface 373.
4 is fixed. Each of the yokes 364 and 374 is made of a material having a high magnetic permeability, like the cores 361 and 371. In the present embodiment, these yokes 3
The gap between 64 and 374 is the detection gap 323, and the gap length L is set according to the same procedure as in the first embodiment.

As described above, in this embodiment, each magnet 362
Since the yokes 364 and 374 are fixed to the opposing magnetic pole surfaces 363 and 373 of the Hall element 372, respectively.
It is possible to suppress a change in the sensor characteristics due to the displacement of the position 22.

For example, unlike this embodiment, each magnet 36
In the configuration in which the yokes 364 and 374 are not attached to the magnets 2 and 372, as shown in FIG.
The magnetic flux between 62 and 372 expands to the side. For this reason, the change in the magnetic flux density between each of the magnets 362 and 372 becomes large both in the axial direction of the valve shaft 21 and in the direction perpendicular to the same direction, and the displacement of the Hall element 322 greatly affects the sensor characteristics. Become like

That is, as described above, the respective yokes 364 and 374
Is omitted, as shown by the alternate long and short dash line in FIG. 11, the Hall element 322 is displaced in the direction approaching and separating from the valve shaft 21 (the left-right direction in FIG. 10A). The magnetic flux density at the position 322 greatly changes. Further, as shown by a dashed line in FIG. 12, the axial direction of the valve shaft 21 (FIG.
Similarly, the magnetic flux density at the position of the Hall element 322 greatly changes due to the positional deviation of the Hall element 322 in the vertical direction (a). Therefore, in the above configuration, it is necessary to accurately position the Hall element 322 such that such a change in the magnetic flux density does not occur.

On the other hand, in the present embodiment, each magnet 36
Each yoke 3 having an extremely high magnetic flux from
As a result, the magnetic flux between the magnets 362 and 372 becomes substantially parallel as shown in FIG. Therefore, the variation of the magnetic flux density between the magnets 362 and 372 is reduced, and as shown by the solid line in FIGS. 11 and 12, even when the position of the Hall element 322 is shifted, the change of the magnetic flux density at the position of the element 322 is possible. The amount will be very small.

As a result, according to the present embodiment, it is possible to suppress a change in the sensor characteristics due to the displacement of the Hall element 322, and to detect the throttle opening θ with higher accuracy.

Further, in this embodiment, each of the magnets 362, 3
The magnets 36 are not evenly magnetized and these magnets 36
Even if the magnetic flux density inside the second and second parts 372 is partially different, the variation in the magnetic flux density can be reduced by the yokes 364 and 374, so that the throttle opening with higher accuracy can be achieved in this point as well. θ can be detected.

In the structure in which the throttle valve 20 is driven to be opened and closed by the throttle motor 13 as in this embodiment, metal abrasion powder is generated due to engagement of the gears 12, 13a and 14, and this metal powder is generated. If adheres to the vicinity of the Hall element 322 or the detection gap 323, the output characteristics of the Hall element 322 and the magnetic flux density in the detection gap 323 may change, and the sensor characteristics may slightly deviate from the predetermined characteristics.

In this regard, in this embodiment, each gear 12, 1
Since the meshing portion of 3a and 14 and the Hall element 322 and the detection gap 323 are arranged further apart, the change of the sensor characteristics caused by the metal powder as described above is prevented.

Further, in the present embodiment, the throttle motor 13 which generates magnetic flux by itself, and the driven gear 1 which may affect the magnetic flux density in the detection gap 323,
The metal element such as the Hall element 322 and the detection gap 3
Because it is separated from 23, it has a more desirable configuration in order to reliably suppress a change in sensor characteristics.

As a result, according to the present embodiment, it is possible to stabilize the sensor characteristics and detect the opening degree with higher accuracy. Also, as described above, the gears 12, 13a, 14
When the metal powder is generated by the engagement of the
There is a concern that it will adhere to the first wiring pattern (not shown). Therefore, the substrate 321 and the gears 12 and 13
When the meshing portions a and 14 are close to each other, a resin layer that covers the wiring pattern on the substrate 321 is formed by, for example, resin potting, and the resin layer suppresses adhesion of metal powder to the wiring pattern. It is desirable to do.

On the other hand, in the configuration according to the present embodiment, since the substrate 321 and the meshing portions of the gears 12, 13a, and 14 are separated from each other, such a resin layer is formed on the substrate. This eliminates the need, and in this regard, the cost of the throttle sensor 30 can be reduced.

[Third Embodiment] Next, a third embodiment according to the present invention will be described.
This embodiment will be described focusing on the differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the first embodiment, the first magnetic path component 360 and the second magnetic path component 3 are obtained by dividing the magnetic path component 35.
In the present embodiment, the magnetic path constituting member 35 is integrally formed.
Is different from the embodiment of FIG.

As shown in FIG. 13, the magnetic path constituting member 35 includes a first core 380 fixed to the side of the driven gear 12 and a second core 38 fixed to one end of the valve shaft 21.
1 and a center magnet 382 connecting these cores 380 and 381.

The portion corresponding to the movable magnet 362 and the plate portion 361a of the movable core 361 described in the first embodiment corresponds to the first core 380 of the present embodiment. Further, the portion corresponding to the fixed magnet 372 and the disk portion 371a of the fixed core 371 described in the first embodiment corresponds to the second core 381 of the present embodiment. And
In each of the cores 380 and 381, the gap between the portions facing each other across the substrate 321 is a detection gap 323, and the gap length L is set according to the same procedure as in the first embodiment. Further, of the opposing surfaces 383, 384 of the respective cores 380, 381, the opposing surface 383 of the first core 380 is an inclined surface that extends in a helical manner with respect to the axis of the valve shaft 21. 2
The opposing surface 384 of the core 381 is a vertical surface perpendicular to the coaxial line.

The center magnet 382 has a circular tubular shape, penetrates a substrate 321 attached to a case (not shown), and is fitted and fixed to one end of the valve shaft 21. One end of the center magnet 382 is connected to the second core 381.
The other end is fixed to the first core 380, respectively. Accordingly, each of the cores 380 and 381 and the center magnet 382 rotate integrally with the valve shaft 21.

In the present embodiment, as shown by the dashed line B in FIG. 13, a closed magnetic path is formed by the magnetic flux generated in the center magnet 382, and this magnetic flux is
Except for the gap between the cores 80 and 381, it passes through the center magnet 382 and the inside of both cores 380 and 381. The closed magnetic path includes a central magnetic path composed of a central magnet 382 and both cores 380 and 3.
81, the cross-sectional area of the magnetic flux passing through the outer magnetic path is larger than the cross-sectional area of the magnetic flux passing through the central magnetic path.

As described above, in the present embodiment, the magnetic path constituting member 35 is integrally formed, and the center magnet 382 is interposed between the opposing cores 380 and 381. For this reason, for example, even when the vibration of the engine or the vibration accompanying the traveling of the vehicle is transmitted to each of the cores 380 and 381, the fluctuation of the gap length L due to the vibration is suppressed. Further, as compared with a configuration in which the magnetic path constituting body 35 is divided into a plurality of members, and these members are respectively assembled to the valve shaft 21 and the case 31, the gap length L caused by an assembly error of each member is reduced. Variation is reduced. Therefore, according to the present embodiment, the gap length L can be maintained at a predetermined size by suppressing the variation and the variation of the gap length L. In this regard, the detection accuracy of the throttle sensor 30 can be reduced. Improvement can be achieved.

Since the rare earth cobalt material generally used as a material for forming the magnet is more expensive than iron, steel, etc., the total volume of the magnet is reduced in order to reduce the cost of the throttle sensor 30. It is desirable to do.

In this regard, in the present embodiment, the center magnet 382 as the magnetic flux generator is arranged on the center magnetic path having a smaller cross-sectional area than the outer magnetic path. As a result, in the present embodiment, the movable magnet 362 and the fixed magnet 3
Throttle sensor 30 in each embodiment including
The total volume of the magnets used in the throttle sensor 30 can be significantly reduced as compared with the case of, and the cost can be reduced.

In this embodiment, a pair of magnets 362 and 362 are used.
Unlike the first embodiment in which the detection gap 323 is formed by making the detection gaps 323 face each other, each core 380, 3
The detection gaps 323 are formed so as to face each other. Therefore, similarly to the second embodiment, the magnetic flux in the detection gap 323 is substantially parallel.
As a result, according to the present embodiment, similarly to the second embodiment, it is possible to suppress a change in sensor characteristics due to a positional shift of the Hall element 322 and to detect the throttle opening more accurately.

[Fourth Embodiment] Next, a fourth embodiment according to the present invention will be described.
This embodiment will be described focusing on the differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, in addition to the point that the other end side of the valve shaft 21 is driven and connected to a throttle motor (not shown), and that the magnetic path structure 35 is integrally formed, The first embodiment differs from the first embodiment in that both the first magnet 400 and the second magnet 401 constituting the magnetic flux generator are formed of plastic magnets.

As shown in FIG. 14, the magnetic path constituting member 35 includes a first core 390 and a second
, A circular tube portion 392 which is externally fitted to and fixed to the valve shaft 21, a first magnet 400, and a second magnet 401.

FIG. 15 is a sectional view taken along line AA of FIG. 14, and FIG. 16 is a sectional view taken along line BB of FIG. As shown in FIG. 15, the first core 390 has an annular fixing portion 390 a and an opposing portion 39 fixed to the fixing portion 390 a and opposed to the second core 391 with the substrate 321 interposed therebetween.
0b. The first core 390 is fixed to the other end of the circular tube portion 392 by a first magnet 400 interposed between the inner wall of the fixing portion 390a and the peripheral wall of the other end portion of the circular tube portion 392.

The first magnet 400 is formed by a plastic magnet. This plastic magnet is obtained by mixing fine powder of a magnetic alloy with a binder composed of a resin such as NBR (butadiene / acrylonitrile copolymer) rubber, PA (polyamide), PPS (polyphenylene sulfide), and EP (epoxy). It is. In this embodiment, a PPS resin having particularly high mechanical strength is used as the binder.

The plastic resin can be molded in the same manner as ordinary resins. In the present embodiment, the first magnet 400 is formed by utilizing the characteristics of the plastic magnet. That is, as shown in FIG. 15, the first core 390 is formed such that a predetermined gap is formed between the inner wall of the fixing portion 390a and the peripheral wall of the circular tube portion 392.
And the circular tube part 392 is arranged concentrically. Then, a molten plastic magnet is molded and solidified in the gap between the first core 390 and the circular tube portion 392. As a result, an annular first magnet 400 is formed between the two members 390 and 392, as shown in the figure, and the first core 390 is formed by the first magnet 400 into the circular tube portion 3.
92 fixed. Also, as shown in FIGS. 14 and 15, a projection 390c on the inner wall of the fixing portion 390a and the peripheral wall of the circular tube portion 392 for preventing the first magnet 400 from dropping off from both members 390, 392. , 392c are formed respectively.

On the other hand, the second magnet 401 is also the first magnet 40
Like P.0, it is formed of a plastic magnet using PPS resin as a binder. As shown in FIG. 16, both members 39 are formed such that a predetermined gap is formed between the inner wall of the second core 391 having an annular shape and the peripheral wall of the circular tube portion 392.
1,392 are arranged concentrically. And the second core 3
A plastic magnet is molded and solidified in the gap between 91 and the circular tube portion 392. As a result, both members 391, 3
An annular second magnet 401 is formed between the second magnets 92 and the second core 39 is formed by the second magnet 401.
1 is fixed to the circular tube portion 392. FIG.
As shown in FIG. 16, the inner wall of the second core 391 and the cylindrical portion 3
The second core 3 is provided on the peripheral wall of the second member 92 by the members 391 and 392.
Ridge 391 for preventing 91 from falling off
d and 392d are respectively formed.

As described above, each of the cores 390, 391, the circular tube portion 392, and each of the magnets 400, 4 constituting the magnetic path constituting member 35.
01 are fixed to each other.
90 to 392, 400, and 401 rotate integrally with the valve shaft 21. In addition, a gap between each of the cores 390 and 391 facing each other across the substrate 321 is a detection gap 323, and the gap length L is set according to the same procedure as in the first embodiment. Further, opposing surfaces 393, 3 opposing each other in each core 390, 391.
94, the facing surface 393 of the first core 390 is an inclined surface that extends helically while being inclined with respect to the axis of the valve shaft 21, and the facing surface 394 of the second core 391 with respect to the coaxial line. It is a vertical plane.

As described above, according to the present embodiment, the other end of the valve shaft 21 is drivingly connected to the throttle motor 13, so that the engagement portion is formed similarly to the second embodiment. As a result, it is possible to stabilize the sensor characteristics and reduce the cost of the throttle sensor 30 by avoiding the adverse effect of the metal powder generated from the above. Further, also in the present embodiment, since the cores 390 and 391 face each other to form the detection gap 323, the magnetic flux in the gap 323 becomes substantially parallel. As a result, similarly to the second embodiment, the change in the sensor characteristics due to the displacement of the Hall element 322 is reduced, and the throttle opening can be detected with higher accuracy. In addition, since the magnetic path constituting member 35 is integrally formed, the gap length L can be stably maintained at a predetermined size, as in the third embodiment. Accuracy can be improved.

Further, in this embodiment, each core 390, 39
The first magnet 400 and the second magnet 4 are molded by molding a plastic magnet between the first magnet 400 and the cylindrical portion 392.
01 and the respective cores 390, 391 are fixed to the circular tube portion 392.

For example, unlike this embodiment, each magnet 40
In the case where 0, 401 is formed of a normal metal-based material, the magnets 400, 401 and the circular tube 39 are used.
In order to integrate the core 2 and the cores 390 and 391, it is necessary to fix these members 390 to 392, 400 and 401 with an adhesive or the like. However, when such an adhesive is used, these members 390 to 392, 4
If the bonding surfaces at 00 and 401 are not processed into a shape that allows close contact, sufficient adhesive strength cannot be ensured, and there is a concern that the structural strength of the magnetic path structure 35 may be reduced. For this reason, for example, each member 390-392,400,
The magnetic path constituting body 3 is formed by casting 401 with resin.
In some cases, it is necessary to secure the structural strength of No. 5.

In this regard, according to the present embodiment, each member 390-39 is molded by molding a plastic magnet.
Since 2,400,401 are integrated,
The magnetic path constituting member 35 can be configured without causing the above-described decrease in structural strength. Therefore, it is possible to reliably prevent the magnetic path constituting member 35 from being damaged due to, for example, vehicle vibration, and to improve the structural strength of the throttle sensor 30 and, consequently, its reliability.

Further, according to the present embodiment, each magnet 400,
Since the formation of 401 and the integration of the magnetic path component 35 can be performed simultaneously, the magnetic path component 35 can be formed more easily. Further, according to the present embodiment, as described above, it is not necessary to cast the magnetic path constituting body 35 with the resin, so that the configuration of the magnetic path constituting body 35 can be simplified.

[Fifth Embodiment] Next, a fifth embodiment according to the present invention will be described.
This embodiment will be described focusing on the differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The present embodiment is different from the first embodiment in that the first magnetic path constituting section 360 is disposed closer to one end of the valve shaft 21 than the second magnetic path constituting section 370. The difference from the first embodiment is that θ is changed between a case where the angle is in the low opening region and a case where θ is in the high opening region.

As shown in FIG. 17, the valve shaft 21
Extends through a substrate 321 fixed to a case (not shown). A driven gear 12 is fixed to one end of the valve shaft 21, and a movable core 361 is adjacent to the gear 12. Fixed. This movable core 36
One cylindrical portion 361b is externally fitted and fixed to one end of the valve shaft 21. The movable magnet 362 is fixed to the movable core 361 such that the magnetic pole surface 363 faces the other end of the valve shaft 21.

On the other hand, an annular fixed magnet 372 is concentrically located with the valve shaft 21 and fixed to the substrate 321, and the fixed core 371 is fixed to the fixed magnet 372. The fixed core 371 has an outer peripheral portion fixed to a fixed magnet 372 and a disk portion 371 a and a disk portion 371.
and a cylindrical portion 371c integrally formed at the center portion of a and into which the valve shaft 21 is inserted. The inner diameter of the cylindrical portion 371c is set to be larger than the diameter of the valve shaft 21.
It can rotate relative to c.

The Hall element 322 is formed on the substrate 321 by the magnetic pole surfaces 36 of the movable magnet 362 and the fixed magnet 372.
3, 373, and a gap between both magnetic pole surfaces 363, 373 is a detection gap 323. The gap length L of the detection gap 323 is set according to the same procedure as in the first embodiment.

Further, in the first embodiment, the rate of change of the output signal V with respect to the throttle opening θ is set to be constant as shown in FIG. 7, whereas in the present embodiment, as shown in FIG. Throttle opening θ is in the low opening range (θmin ≦ θ ≦
θmid), the opening θ is in the high opening region (θmid
.Ltoreq..theta..ltoreq..theta.max), the rate of change of the output signal V is set higher. The procedure for setting the change rate of the output signal V in this manner is the same as in the first embodiment.
That is, the throttle opening θ is in a low opening region (θmin ≦ θ ≦ θm
id) and the high opening area (θmax ≦ θ ≦ θmax)
(10)-
By determining the gap length L (θ) based on (13), output characteristics as shown in FIG. 18 can be obtained.

In the configuration according to the present embodiment, the linearity between the throttle opening .theta. And the output signal V is lost in the full opening range (.theta.min.ltoreq..theta..theta.max) of the throttle opening .theta. (Θmin ≦ θ ≦ θmid) and the high opening area (θmi
In each region of d ≦ θ ≦ θmax), the linearity between the same opening degree θ and the output signal V is still ensured. Therefore, as shown in the following equation (15), the throttle opening θ can be obtained from the signal V only by switching the coefficient k in the equation (14) according to the magnitude of the output signal V. Therefore, similarly to the first embodiment, a function map for signal conversion is not required, and it is not necessary to convert the output signal V using the map.

[0106]

[Equation 11] In the equation (15), Vmax is an output signal V corresponding to the maximum value θmax of the throttle opening θ, and Vmin is an output signal V corresponding to the minimum value θmin of the throttle opening θ. Vmid is the output signal V corresponding to the throttle opening θmid when the change rate of the output signal V is switched.

According to the present embodiment configured as described above, the output characteristics of the throttle sensor 30 are suitable for executing more accurate idling speed control. That is, in the electronically controlled throttle valve in which the opening degree of the throttle valve 20 is changed by the throttle motor 13 as in the present embodiment, in order to maintain a predetermined idling speed, the throttle in the low opening range is used. It is necessary to control the opening degree θ with extremely high accuracy.
Therefore, it is desired that the throttle sensor applied to such an electronically controlled throttle valve has a higher resolution as the throttle opening θ is in a lower opening range.

In this regard, according to the present embodiment, when the throttle opening θ is in the low opening range, the throttle opening θ
Since the rate of change of the output signal V with respect to the change in the throttle opening is set relatively large, the throttle opening θ can be detected with higher resolution during idling operation. As a result, according to the present embodiment, more accurate idling speed control can be performed.

Each of the above embodiments can be modified as follows. Even if the configuration is changed in this way, the same operation and effect as the above embodiments can be obtained. In the fifth embodiment, the one end side of the valve shaft 21 to which the first magnetic path constituting portion 360 is fixed is drivingly connected to the throttle motor 13. On the other hand, similarly to the second embodiment, the other end of the valve shaft 21 may be drivingly connected to the throttle motor 13.

In the above embodiments, the rotation angle sensor according to the present invention is applied to a throttle sensor. However, the rotation angle sensor according to the present invention can also be applied to an accelerator sensor for detecting the amount of depression of an accelerator pedal of a vehicle.

In the first embodiment, each magnetic path constituting unit 3
Although the magnets 362 and 372 are provided in the respective 60 and 370, the configuration may be changed to a configuration in which at least one of the magnetic path constituting parts 360 and 370 is provided with the magnet.

In the first embodiment, the movable core 361 is used.
And the driven gear 12 are provided as separate members, but the plate portion 361a of the movable core 361 is formed in a disk shape, and a gear meshing with the reduction gear 14 is formed on the outer periphery of the plate portion 361a. This allows the movable core 361 to have the same function as the driven gear 12. According to such a configuration, the driven gear 12 can be omitted to simplify the structure.

In the fifth embodiment, the rate of change of the output signal V with respect to the throttle opening θ is changed in two stages according to the magnitude of the throttle opening θ. It is also possible to switch among three or more steps according to the resolution.

In each of the above embodiments, the throttle sensor 30 detects the opening of the electronically controlled throttle valve.
However, the throttle valve to which the sensor 30 is applied may be of a type that is mechanically connected to an accelerator pedal and that opens and closes in response to depression of the pedal.

[0115]

According to the first aspect of the present invention, one of the opposing surfaces of the opposing portions in the magnetic path constituting member is a helical inclined surface inclined with respect to the axis of the rotating shaft, and the other is a coaxial line. The vertical plane is perpendicular to the plane. Therefore, even when the positions of the facing portions are relatively shifted in the circumferential direction of the rotation axis, the predetermined relationship set between the angle around the rotation axis and the distance between the facing surfaces may change. Absent. As a result, it is possible to suppress the occurrence of distortion of the sensor characteristics due to the displacement of the facing portions.

According to the second aspect of the present invention, in the rotation angle sensor according to the first aspect, the distance L (θ) between the opposing surfaces in the axial direction of the rotation axis is a function of the angle θ about the rotation axis: L (Θ) = √ (αθ + β) + γ (α,
(β and γ are constants). Therefore, the magnitude of the magnetic flux density between the opposing portions changes linearly with the change in the angle θ around the rotation axis, and the magnetic detection body linearly changes with the change in the rotation angle on the rotation axis. Is output. For this reason, according to the rotation angle sensor according to the present invention,
Even when a detection signal that changes linearly with respect to a change in the rotation angle is required, there is no need to prepare a conversion map for converting the detection signal, and signal processing using the map is not necessary. Can be omitted.

According to the third aspect of the present invention, the magnetic path constituting member is constituted by a plurality of magnetic path constituting sections, and a plastic magnet serving as a magnetic flux generating section is molded between the respective magnetic path constituting sections. The components are integrally formed. Therefore, unlike the case where each magnetic path component is fixed using an adhesive, even if the joint surface of each magnetic path component is not processed into a shape that can be in close contact, each magnetic path component is Are reliably integrated. As a result, sufficient structural strength of the magnetic path component can be ensured, and damage to the magnetic path component due to vehicle vibration or the like can be prevented, and the reliability of the throttle sensor can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a throttle sensor according to a first embodiment.

FIG. 2 is a sectional view showing a main part of the throttle sensor.

FIG. 3 is a front view showing a first magnetic path component of the throttle sensor.

FIG. 4 is a perspective view showing a movable magnet of a first magnetic path constituting unit.

FIG. 5 is a graph showing a relationship between a throttle opening and a gap length.

FIG. 6 is a graph showing a relationship between a throttle opening and a magnetic flux density.

FIG. 7 is a graph showing a relationship between a throttle opening and an output signal.

FIG. 8 is a sectional view showing a throttle sensor according to a second embodiment.

FIG. 9 is a sectional view showing a main part of the throttle sensor.

FIG. 10 is a cross-sectional view showing a distribution state of magnetic flux.

FIG. 11 is a graph showing the relationship between the displacement of the Hall element and the magnetic flux density.

FIG. 12 is a graph showing the relationship between the displacement of the Hall element and the magnetic flux density.

FIG. 13 is a sectional view showing a throttle sensor according to a third embodiment.

FIG. 14 is a sectional view showing a main part of a throttle sensor according to a fourth embodiment.

FIG. 15 is a sectional view taken along the line AA of FIG. 14;

FIG. 16 is a sectional view taken along the line BB of FIG. 14;

FIG. 17 is a sectional view showing a throttle sensor according to a fifth embodiment.

FIG. 18 is a graph showing a relationship between a throttle opening and an output signal.

FIG. 19 is a perspective view showing a conventional open magnetic circuit type rotation angle sensor.

FIG. 20 is a perspective view showing a conventional closed magnetic circuit type rotation angle sensor.

FIG. 21 is a front view of the closed magnetic circuit type rotation angle sensor.

FIG. 22 is a graph showing a relationship between a throttle opening and an output signal in the closed magnetic circuit type rotation angle sensor.

[Explanation of symbols]

21: valve shaft, 30: throttle sensor, 35
... Magnetic path component, 322 Hall element, 323 Detection gap, 360 First magnetic path component, 362 Movable magnet, 363 Magnetic pole surface, 370 Second magnetic path component, 37
2 ... fixed magnet, 373 ... pole face, 382 ... center magnet, 3
83, 384: Opposing surface, 393, 394: Opposing surface, 40
0 ... first magnet, 401 ... second magnet.

Claims (3)

[Claims] 1. A magnetic path comprising a magnetic flux generating part and a pair of opposing parts opposing each other with a magnetic detection body interposed therebetween to form a closed magnetic path for magnetic flux passing through the magnetic detection body. The magnetic flux density at the same position is changed by changing the distance between the opposing portions at the position of the magnetic detection body in response to the rotation of the magnetic detector, and the rotation angle of the rotating shaft is detected from the magnitude of the magnetic flux density. In the rotation angle sensor, one of the opposing surfaces of the opposing portions is a helical inclined surface inclined with respect to the axis of the rotating shaft, and the other is a vertical surface perpendicular to the coaxial line. Rotation angle sensor. 2. The rotation angle sensor according to claim 1, wherein a distance L (θ) between the facing surfaces in the axial direction of the rotation axis is a function of an angle θ about the rotation axis:
2. The rotation angle sensor according to claim 1, wherein the rotation angle sensor is set based on L (θ) = √ (αθ + β) + γ (α, β, and γ are constants). 3. The rotation angle sensor according to claim 1, wherein the magnetic path component includes a plurality of magnetic path components, and a plastic magnet serving as the magnetic flux generator is molded between the magnetic path components. The rotation angle sensor is formed integrally by performing the rotation angle sensor.