Source: http://www.allindianpatents.com/patents/239352-rotation-angle-detecting-device
Timestamp: 2018-02-22 04:53:40
Document Index: 237165342

Matched Legal Cases: ['art 123', 'art 124', 'art 123', 'art 125', 'art 124', 'art 125', 'art) 34', 'art 34', 'art 34', 'art 32', 'art) 33', 'art 32', 'art 34', 'arts 34', 'arts 34', 'arts 34', 'arts 34', 'arts 32', 'arts 33', 'arts 34', 'art 34', 'art 32', 'art 32', 'art 33', 'art 34', 'art 34', 'art 33', 'art 32', 'art 32', 'art 33', 'art 34', 'arts 34']

Indian Patents. 239352:ROTATION ANGLE DETECTING DEVICE
A rotation angle detecting device for detecting a rotational angle of an object includes a magnet (4), a magnetic substance unit (5), and a non-contact magnetic detection element (7).&nbsp; The magnet (4) rotates with the object and includes two ends magnetized to have opposite polarities.&nbsp; The magnetic substance unit (5) forms an air gap with the two ends of the magnet (4) and includes magnetic members (6) disposed substantially symmetrically relative to a vertical&nbsp;plane perpendicularly through a rotational axis of the magnet (4) and defining a magnetic detection gap (9) therebetween.&nbsp; The non-contact magnetic detection element (7) is disposed in the magnetic detection gap (9) between the magnetic members (6) for outputting a signal corresponding to a density of a magnetic flux passing through the magnetic detection gap (9).&nbsp; The rotation angle of the object is detected based on the signal output from the magnetic detection element (7).&nbsp; The magnetic members (6) each include a reverse warp part (34) so that the air gap suddenly increases when the magnet (4) rotates to a predetermined rotation angle from a state where the air gap is minimum in a direction in which the air gap increases.
FIELD OF THE INVENTION The present invention relates to a rotation angle detecting device for detecting a rotation angle of an object to be measured and, more particularly, to a throttle opening detecting device for detecting a rotation angle of a throttle valve for regulating the amount of intake air sucked into a cylinder of an internal combustion engine.
BACKGROUND OF THE INVENTION Conventionally, as a rotation angle detecting device for detecting a rotation angle of an object to be measured, for example, a throttle opening sensor (also referred to as a throttle position sensor) for detecting the degree of opening of a throttle valve (throttle opening) of an internal combustion engine has been proposed. One such example is disclosed in Japanese Patent document JP 2001-317909 A. This is, as shown in Figs. 8A and 8B, such that a rotating shaft 101 of an object to be measured such as a throttle valve (not shown) is rotatably supported by a housing 103 through a bearing 102. A cylindrical rotor core (corresponding to a yoke) 104 is fixed to one of the ends of the rotating shaft 101. On an inner circumferential side of the rotor core 104, a columnar stator core 105 is coaxially arranged. A magnet 107 is fitted into each of two notches 106 in the rotor core 104 so as to be fixed thereto. Each of the two magnets 107 is formed to have a planar or columnar shape. On both end faces thereof, an N-pole and an S-pole are magnetized in parallel. An inner circumferential face of the rotor core 104 is opposed to an outer circumferential face of the stator core 105 through a small air gap therebetween except for the
vicinity of each of the magnets 107. On the other hand, a magnetic detection gap 109 having a constant width for forming a parallel magnetic field is formed in the middle of the stator core 105 so as to penetrate therethrough in a diameter direction. Two Hall ICs 110 are horizontally arranged in the magnetic detection gap 109.
Since the two magnets 107 are arranged at the opposed positions in the diameter direction of the rotor core 104 so as to repel each other in the throttle opening sensor configured as described above, magnetic flux generated from the N-pole of each of the magnets 107 passes through a magnetic path from the rotor core 104, the stator core 105, the magnetic detection gap 109 (the Hall ICs 110), the stator core 105 to the rotor core 104 so as to return to the S-pole of each of the magnets 107. When the rotor core 104 rotates with the rotation of the object to be measured such as the throttle valve, a density of magnetic flux passing through the magnetic detection gap 109 in the stator core 105 (a magnetic flux density crossing the Hall ICs 110) varies in accordance with its rotation angle. In accordance with the magnetic flux density, an output voltage from the Hall ICs 110 varies. In the throttle opening sensor shown in Fig. 8A a relatively large air gap 111 is formed in the vicinity of each of the magnets 107 on the inner circumferential side of the rotor core 104. As a result, short-circuit of the magnetic flux between both poles of each of the magnets 107 and the stator core 105 can be prevented by the air gap 111, thereby preventing the density of the magnetic flux passing through the magnetic detection -gap 109 (the Hall ICs 110) from being lowered.
Moreover, as shown in Figs. 6A and 9, a rotation angle sensor retaining the Hall IC 110 in a magnetic detection gap 122 formed between retaining pieces 121 of divided-type stator cores 120 has been proposed in U.S. Patent No. 6,707,292 B2. When a rectangular parallelepiped magnet 130 rotates with the rotation of an object
to be measured, a density of magnetic flux passing through the magnetic detection gap 122 (a density of magnetic flux crossing the Hall IC 110) changes in accordance with its rotation angle. In accordance with the density of the magnetic flux, an output voltage of the Hall IC 110 changes. Each of the stator cores 120 includes a shoulder part 123 extended from a lower end of the retaining piece 121 in the drawing to a horizontal direction in the drawing; a bent part 124 obtained by bending at an end of the shoulder part 123; and an extended part 125 extended from an end of the bent part 124 in a straight manner to the lower end in the drawing.
In the throttle opening sensor described in Japanese Patent document JP 2001-317909 A, however, and as shown in Figs. 8Aand 8B, the Hall ICs 110 are held in a connector housing 114 obtained by resin molding of a terminal 112, to which lead wirings of the Hall ICs 110 are connected, the stator core 105, the spacer 113 and the like. Specifically, since the housing 103 for rotatably retaining the rotor core 104 and the two magnets 107 and the connector housing 114 for retaining the stator core 105 and the Hall ICs 110 are constituted by separate components, the positional accuracy (combination accuracy) of the stator core 105 and the Hall ICs 110 with respect to a magnetization direction of the two magnets 107 can hardly be obtained. Therefore, a variation in output from the Hall ICs 110 is likely to occur. As a result, there arises a problem that detection accuracy of the rotation angle of the magnets 107 rotating with the rotation of the object to be measured is lowered. Moreover, since two magnets 107 are provided as magnetic field sources, the number of components and the number of assembly steps are increased, resulting in a problem of increased cost.
Moreover, in the rotation angle sensor described in U.S. Patent No. 6,707,292 B2, and as shown in Figs. 6A and 9, while the rotation angle of the magnet
130 changes from the minimum angle (for example, 0°) to the vicinity of the maximum angle (for example, 80°), an output from the Hall IC 110 changes in accordance with a change in density of the magnetic flux passing through the magnetic detection gap 122. Each of the stator cores 120 includes the straight extended part 125 forming an air gap with both end faces of the magnet 130 when the magnet 130 rotates at a large rotation angle. Therefore, an output with a convex profile having an inflection point in the vicinity of the maximum angle is generated, rather than an ideal output, as indicated with a solid line in a graph of Fig. 10 presented herein according to the present invention. More specifically, a difference between the output from the Hall IC 110 and the ideal output becomes the largest when the rotation angle of the magnet 130 is in the vicinity of 45°. As a result, there arises a problem that linearity of the output value of the Hall IC 110 with respect to the rotation angle of the magnet 130, which rotates with the rotation of the object to be measured, is degraded within the range of the detected angle of the object to be measured.
SUMMARY OF THE INVENTION An object of the present invention is to provide a rotation angle detecting device capable of improving detection accuracy of a rotation angle of an object to be measured by improving linearity of an output signal from a magnetic detection element with respect to rotation angles of the object to be measured and a magnet over a full range of a detected angle of the object to be measured. Moreover, an object of the present invention is to provide a rotation angle detecting device capable of preventing the detection accuracy of the rotation angle of the magnet rotating with the rotation of the object to be measured from being lowered by constituting a
housing for rotatably holding the magnet therein and a housing for retaining magnetic members and the magnetic detection element therein by a single component
According to one aspect of the present invention, a magnetic substance unit is divided so as to provide plane symmetry with respect to a vertical plane approximately perpendicularly crossing a rotational center axis of a magnet, and a magnetic detection element is placed in a magnetic detection gap formed by the division, A reverse warp part is provided for each of the magnetic members so that an air gap suddenly increases if the magnet rotates at a predetermined rotation angle from a state where the air gap is minimum in a direction in which the air gap increases. As a result, with the rotation of an object to be measured at a predetermined rotation angle in the direction in which the air gap increases, the air gap formed between both ends of the magnet in the magnetization direction and the inner faces (the opposed surfaces) of the magnetic members in a plate-thickness direction suddenly increases. Therefore, a density of magnetic flux passing through the magnetic detection gap between the magnetic members, that is, a density of magnetic flux crossing the magnetic detection element suddenly decreases.
As a result, since an output signal from the magnetic detection element is also suddenly lowered, the output signal approaches an ideal output signal as compared with that in the conventional techniques. Therefore, linearity of the output signal from the magnetic detection element (linearity of an output variation characteristic of the magnetic detection element) with respect to rotation angles of the object to be measured and the magnet over a full range of the detected angle of the object to be measured can be improved. In particular, since the linearity of the output signal from the magnetic detection element (the linearity of the output variation characteristic of the magnetic detection element) with respect to the rotation angle of
the magnet in an area where the air gap is relatively small can be improved, the detection accuracy of the rotation angle of the object to be measured can be improved.
According to still another aspect of the present invention, by providing a sensor retaining section for retaining a rotation angle sensor including magnetic members and a magnetic detection element, and a magnet holding hole for rotatably holding a magnet therein for a housing integrally formed of a non-magnetic material, a housing for rotatably holding the magnet therein and a housing for retaining the magnetic members and the magnet detection element therein can be constituted by a single component. As a result, the positional accuracy (combination accuracy) of the magnetic members and the magnetic detection element with respect to the magnetization direction of the magnet can be easily obtained, thereby reducing a variation in assembly of the magnet and the magnetic members and the magnetic detection element. Moreover, since a variation is hardly generated in output from the magnetic detection element, the detection accuracy of the rotation angle of the magnet rotating with the rotation of the object to be measured can be prevented from being lowered. Moreover, since a single magnet is provided as a magnetic field source, the number of components and the number of assembly steps can be reduced as compared with those in the conventional techniques requiring two magnets. As a result, the overall cost of the rotation angle detecting device can be
According to yet another aspect of the present invention, magnetic detection element retaining pieces, each having a smaller width than that of the reverse warp parts for concentrating the magnetic flux of the magnet thereon, are provided for the magnetic members, respectively. Then, if the respective magnetic detection element retaining pieces of the magnetic members are provided so as to be opposed to each other through the magnetic detection gap while being in contact with both
magnetically sensitive faces of the magnetic detection element in the plate-thickness direction, the magnetic flux can be concentrated on both magnetically sensitive faces of the magnetic detection element in the plate-thickness direction. As a result, the magnetic flux can be concentrated on both magnetically sensitive faces of the magnetic detection element in the plate-thickness direction efficiently over the range of the rotation angle in which the magnet rotates from the minimum angle to the maximum angle with the rotation of the object to be measured, that is, over a full range of the detected angle of the object to be measured. Therefore, a stable output signal can be obtained from the magnetic detection element.
Fig. 2B is a cross-sectional view taken through line A-A of Fig. 2A;
Fig. 3A is a front view of the throttle opening sensor of Fig. 1 showing a magnetic flux flow at a valve opening angle of 30° with the minimum output;
Fig. 7 is a cross-sectional view of an inlet throttle device for internal
combustion engine according to a second embodiment of the present nvention;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the best mode for carrying out the present invention, the object of improving the detection accuracy of a rotation angle of an object to be measured is realized by improving the linearity of an output signal from a magnetic detection element with respect to a rotation angle of a magnet over a full range of a detected angle of the object to be measured. Moreover, the object of preventing the detection accuracy of the rotation angle of the magnet rotating with the rotation of the object to be measured from being lowered is realized by constituting a housing for holding the magnet rotatably therein and a housing for retaining the magnet detection element therein by a single component.
The inlet throttle device for internal combustion engine is a throttle device for an internal combustion engine, for controlling an engine revolution rate or an engine torque by changing the amount of intake air flowing into a combustion chamber of a cylinder of an internal combustion engine (for example, an engine for two-wheeled
vehicle; hereinafter, referred to as an engine) based on the amount of operation of an accelerator by a driver (for example, the amount of operation of a throttle lever). The inlet throttle device for internal combustion engine includes a throttle valve 1 for controlling the amount of intake air sucked into the cylinder of an engine; a throttle shaft 2 cooperatively rotating with the throttle valve 1; a throttle body 3 through which the intake air toward a cylinder of the engine flows; and an engine control unit (hereinafter, referred to as an ECU; not shown) for controlling the amount of an injected fuel injected and supplied to the cylinder of the engine to an optimal value.
The throttle shaft 2 is made of a non-magnetic material, for example, a non-magnetic metal material in an approximately columnar shape, and has a valve retaining section 10 for retaining and fixing the throttle valve 1, as shown in Fig. 2A. One axial end side (on the right in the drawing) from the valve retaining section 10 serves as a first bearing sliding section slidably supported by an inner circumference
of a first shaft bearing 11 of the throttle body 3. The other axial end side (on the left in the drawing) from the valve retaining section 10 serves as a second bearing sliding section slidably supported by an inner circumference of a second shaft bearing section 12 of the throttle body 3.
The throttle body 3 is a resin-molded article obtained by resin integral molding (resinification) with a non-magnetic material (for example, a resin material such as a thermoplastic resin) and is a device (a housing) for housing and retaining rotatably the throttle shaft 2 and the throttle valve 1 therein. As a resin material for resin integral molding of the throttle body 3, polybutylene terephthalate: PBT, polyphenylene sulfide: PPS, a polyamide resin: PA, polypropylene: PP or polyetherimide: PEI and the like may be used. A cylindrical tube-like bore wall 18 for forming an intake air passage therein is integrally formed with the throttle body 3
as shown in Figs. 2A and 2B. Inside the bore wall 18, the throttle valve 1 is rotatably incorporated.
First and second shaft sliding holes 21 and 22, each having a circular cross section, are formed in the first and second shaft bearing sections 11 and 12. The second shaft bearing section 12 functions as a cylindrical spring inner circumference guide to which the return spring 17 for biasing the throttle valve 1 in a return direction to the full-close position with the minimum amount of intake air is fitted. Moreover, on a left end face of the bore wall 18 in the drawing, a body-side hook section (not shown) for locking the spring-side hook section of the return spring 17 is integrally provided. The return spring 17 is a coil spring attached onto the outer circumferential side of the second bearing sliding section of the throttle shaft 2, that is, onto the outer circumferential side of the second shaft bearing section 12 of the
throttle body 3. Its right end (one end) as shown in the drawing is retained by the body-side hook (not shown) provided on the outer wall face of the bore wall 18 of the throttle body 3, while its left end (the other end) as shown in the drawing is retained by the lever-side hook (not shown) provided on a side face of the bore wall of the accelerator lever 15.
Herein, the inlet throttle device for internal combustion engine in this
embodiment includes a non-contact rotation angle detecting device for converting a rotation angle (a valve angle) of the throttle valve 1 into an electric signal (a throttle opening signal) so as to output the degree of opening of the throttle valve 1 to the engine control unit (ECU). The ECU in this embodiment is configured to perform injection amount control for controlling a valve-opening duration of an electromagnetic fuel injection valve (an injector: not shown) so that the amount of fuel injection corresponding to the throttle opening signal output from the rotation angle detecting device is injected and supplied to the cylinder of the engine. The rotation angle detecting device of this embodiment includes, as shown in Figs. 1 through 6B, the thin-plate magnet 4 fixed to one end of the throttle shaft 2, the throttle opening sensor 5 forming the magnetic circuit with the thin-plate magnet 4 and the like. The throttle opening sensor 5 in this embodiment includes a pair of yokes (magnetic members) 6 magnetized by the thin-plate magnet 4, the Hall IC 7 provided in the magnetic detection gap 9 between the yokes 6 and the like.
The thin-plate magnet 4 is formed in a flat plate-like or a columnar shape; it rotates with the rotation of the throttle valve 1 corresponding to the object to be measured. At the same time, an N-pole and an S-pole are magnetized in parallel so that both ends in a plate-length direction approximately perpendicularly crossing a plate-thickness direction and a plate-width direction have opposed polarities to each other. The thin-plate magnet 4 has a square planar shape, and is a planar permanent magnet stably generating a magnetic force for a long period of time, for which, for example, a rare-earth magnet such as a samarium-cobalt (Sm-Co) magnet and a neodymium (Nd) magnet, an alnico magnet and a ferrite magnet is used. Both ends of the thin-plate like magnet 4 in the plate-length direction (a magnetization direction) are provided so as to face the respective inner
circumferential faces of the pair of yokes 6 with an extremely small air gap therebetween. Herein, the reference numeral 20 indicates a magnet holding hole surrounded by the sensor retaining section 23 of the throttle body 3, in which the thin-plate magnet 4 is rotatable within the rotating operation range from the valve full-close position (the minimum angle) of the throttle valve 1 to the valve full-open position (the maximum angle).
The pair of yokes 6 are made of a magnetic material such as iron, and form a predetermined air gap with both ends of the thin-plate magnet 4 in the magnetization direction. The pair of yokes 6 are divided into two or more parts so that they provide plane symmetry with respect to a vertical plane approximately perpendicularly crossing the rotational center axis of the thin-plate magnet 4. The Hall IC 7 is provided in the magnetic detection gap 9 having certain size formed by the division. Each of the yokes 6 includes an approximately circular curved part (reverse warp part) 34 arranged around the magnet 4 so as to concentrate the magnetic flux of the magnet 4 thereon; a magnetic detection element retaining piece (hereinafter, abbreviated as a retaining piece) 31 having a smaller width than that of the curved part 34 on one side of the curved part 34; a shoulder part 32 connected to an end of
the retaining piece 31; and a bent part (winding part) 33 bent at an end of the shoulder part 32 at an approximately acute angle so as to be connected to the curved part 34.
Each of the reverse warp parts 34 is provided so that the air gap formed between both ends of the thin-plate magnet 4 in the magnetization direction and the inner faces of the pair of yokes 6 suddenly increases as the thin-plate magnet rotates at a predetermined rotational angle from the air gap minimum state to the side where
the air gap increases. Moreover, the reverse warp parts 34 are provided so as to be warped to be separated away from each other. A state where the air gap formed between both ends of the thin-plate magnet 4 in the magnetization direction and the inner faces of the pair of yokes 6 becomes minimum when the throttle valve 1 and the thin-plate magnet 4 are at the vicinity of the maximum angle (for example, 80°) is set as a reference position (at the position where a vertical line with respect to the rotational center axis of the thin-plate magnet 4 crosses). The reverse warp parts 34 are provided so that parts extended from the reference position to both sides (in the vertical direction in the drawing) are curved in an approximately circular manner.
The Hall IC 7 is inserted through the sensor insertion hole 24 so that the Hall IC 7 is fitted into the magnetic detection gap 9 formed between the retaining pieces 31 of the pair of yokes 6 retained and fixed (insert-molded) into the sensor retaining section 23 integrally formed with the outer wall face of the throttle body 3 of a resin, thereby assembling the Hall IC 7 at a predetermined position of the sensor retaining section 23. As a result, the Hall IC 7 is fitted into the magnetic detection gap 9
formed between the retaining pieces 31 of the pair of yokes 6 so as to be positioned. Lead wires of the Hall IC 7 (two output lead terminals and one power supply (electrical supply) terminal) are electrically and mechanically connected to connector pins (terminals: not shown) formed by insert molding into the sensor retaining section 23 by bonding means such as resistance welding.
The magnetic detection gap 9 is provided in the middle of a magnetic circuit including the thin-plate magnet 4 and the pair of yokes 6 so that a positional relation is such that the density of the magnetic flux crossing both magnetically sensitive faces of the Hall IC 7 becomes relatively large with respect to the magnetization direction of the thin-plate magnet 4 in a positional relation where the air gap between the thin-plate magnet 4 and the reverse warp parts 34 of the yokes 6 becomes minimum. Moreover, the magnet detection gap 9 is provided in the middle of the magnetic circuit so that a positional relation is such that the density of the magnetic flux crossing both magnetically sensitive faces of the Hall IC 7 becomes relatively small with respect to the magnetization direction of the thin-plate magnet 4 when the rotation angles of the throttle valve 1 and the thin-plate magnet 4 are situated in the vicinity of a middle angle (for example, 40°) between the minimum angle and the maximum angle.
When the throttle lever is operated by the driver, the accelerator lever 15 mechanically connected to the throttle lever through a wire cable rotates at a rotation angle in accordance with the amount of operation of the throttle lever against a biasing force of the return spring 17. Then, the rotation of the accelerator lever 15
described above is transmitted to the throttle shaft 2. With the rotation of the throttle shaft 2, the throttle valve 1 rotates at the same rotation angle as that of the accelerator lever 15, that is, the throttle shaft 2. As a result, since the intake air passage to the cylinder of the engine is opened at a predetermined degree of throttle opening, the engine revolution rate is changed in accordance with the amount of operation of the throttle lever.
Herein, when the rotation angle of the throttle valve 1 is in the vicinity of the middle angle (when the valve opening of the throttle valve 1 is at 30° in this embodiment and the rotation angle of the thin-plate magnet (magnet) 4 is 0° in this embodiment), as indicated with an arrow in Fig. 3A, the magnetic flux generated from one end (the N-pole) of the thin-plate magnet 4 in the plate-length direction passes through the respective shoulder parts 32 of the pair of yokes 6, the respective bent parts 33 of the pair of yokes 6 and the reverse warp parts 34 of the pair of yokes 6 to return to the other end (the S-pole) of the thin-plate magnet 4 in the plate-length direction. At this time, a positional relation is such that a density of the magnetic flux passing through the magnet detection gap 9 (a density of the magnetic flux crossing the Hall IC 7) becomes relatively small with respect to the magnetization direction of the thin-plate magnet 4. As a result, an output voltage output from the Hall IC 7 for the rotation angles of the throttle valve 1 and the thin-plate magnet 4 becomes almost 0, as shown in a graph of Fig. 5.
Moreover, when the rotation angle of the throttle valve 1 changes from the vicinity of the middle angle in the opening increasing direction (the full-opening direction) (when the valve opening of the throttle valve 1 is at 60° to 70° in this embodiment, and the rotation angle of the thin-plate magnet (magnet) 4 is 30° to 40° in this embodiment), as indicated with an arrow in Fig. 3B, the magnetic flux from one
end (the N-pole) of the thin-plate magnet 4 in the plate-length direction returns to the other end (the S-pole) of the thin-plate magnet 4 in the plate-length direction through the reverse warp part 34 of the left yoke 6 in the drawing. Moreover, the magnetic flux from one end (the N-pole) of the thin-plate magnet 4 in the plate-length direction passes through the shoulder part 32 of the left yoke 6 in the drawing, the retaining piece 31 of the left yoke 6 in the drawing, the magnetic detection gap 9 (the Hall IC 7), the retaining piece 31 of the right yoke 6 in the drawing, the shoulder part 32 of the right yoke 6 in the drawing, the bent part 33 of the right yoke 6 in the drawing and the reverse warp part 34 of the right yoke 6 in the drawing to return to the other end (the S-pole) of the thin-plate magnet 4 in the plate-length direction. At this time, a positional relation is such that a density of the magnetic flux passing through the magnet detection gap 9 (a density of the magnetic flux crossing the Hall IC 7) becomes relatively moderate with respect to the magnetization direction of the thin-plate magnet 4. As a result, an output voltage output from the Hall IC 7 for the rotation angles of the throttle valve 1 and the thin-plate magnet 4 linearly increases in accordance with the amount of change as shown in the graph of Fig. 5.
Then, when the rotation angle of the throttle valve 1 is further greatly changed from the vicinity of the middle angle to the opening increasing direction (in the full-open direction) (when the throttle valve 1 is at the full-open position, that is, the valve opening is at 90° in this embodiment, and the rotation angle of the thin-plate magnet (magnet) 4 is 60° in this embodiment), as indicated with an arrow in Fig. 4A, the magnetic flux from one end (the N-pole) of the thin-plate magnet 4 in the plate-length direction passes through the reverse warp part 34 of the left yoke 6 in the drawing, the bent part 33 of the left yoke 6 in the drawing, the shoulder part 32 of the left yoke 6 in the drawing, the retaining piece 31 of the left yoke 6 in the
drawing, the magnetic detection gap 9 (the Hall IC 7), the retaining piece 31 of the right yoke 6 in the drawing, the shoulder part 32 of the right yoke 6 in the drawing, the bent part 33 of the right yoke 6 in the drawing and the reverse warp part 34 of the right yoke 6 in the drawing to return to the other end (the S-pole) of the thin-plate magnet 4 in the plate-length direction. At this time, a positional relation is such that a density of the magnetic flux passing through the magnet detection gap 9 (a density of the magnetic flux crossing the Hall IC 7) becomes relatively large with respect to the magnetization direction of the thin-plate magnet 4. As a result, an output voltage output from the Hall IC 7 for the rotation angles of the throttle valve 1 and the thin-plate magnet 4 has a maximum value in the linear area as shown in the graph of Fig. 5.
On the other hand, when the rotation angle of the throttle valve 1 is changed from the vicinity of the middle angle to the opening decreasing direction (in the full-close direction) (when the throttle valve 1 is at the full-close position, that is, the valve opening is at 0° in this embodiment, and the rotation angle of the thin-plate magnet (magnet) 4 is -30° in this embodiment), as indicated with an arrow in Fig. 4B, a magnetic flux flow is in a direction reverse to that of the Fig. 3B described above, that is, from the retaining piece 31 of the right yoke 6 in the drawing through the magnetic detection gap 9 (the Hall IC 7) to the retaining piece 31 of the left yoke 6 in the drawing. An output voltage output from the Hall IC 7 is a linear negative output in accordance with the amount of change as shown in the graph of Fig. 5.
As described above, in the rotation angle detecting device in this embodiment, the pair of yokes 6 includes the Hall IC 7 constituting a sensing section of the throttle opening sensor 5 provided in the magnetic detection gap 9 formed between the retaining pieces 31 provided so as to be opposed to each other. The
yokes are divided so as to provide plane symmetry with respect to the vertical plane approximately perpendicularly crossing the rotational center axis of the thin-plate magnet 4. The reverse warp parts 34 curved so as to be respectively warped away from the reference position are provided for the pair of yokes 6. As a result, if the rotation angle of the throttle valve 1 rotates at a predetermined rotation angle from the vicinity of the maximum angle toward the minimum angle, the air gap formed between both ends of the thin-plate magnet 4 in the magnetization direction and the inner faces (the opposed faces) of the pair of yokes 6 suddenly increase. Therefore, the density of the magnetic flux passing through the magnetic detection gap 9 between the pair of yokes 6 (the density of the magnetic flux crossing the Hall IC 7) suddenly decreases.
As a result, since the output voltage from the Hall IC 7 also suddenly drops, it becomes closer to the ideal output voltage as compared with that in the conventional technique. Therefore, the linearity of the output voltage from.the Hall IC 7 with respect to the rotation angles of the throttle valve 1 and the thin-plate magnet 4 (the linearity of the output variation characteristic of the Hall IC 7) over a full range of the detected angle of the throttle valve 1 can be improved. In particular, since the linearity of the output voltage from the Hall IC 7 (the linearity of the output variation characteristic of the Hall IC 7) with respect to the rotation angles of the object to be measured and the thin-plate magnet 4 when the rotation angle of the throttle valve 1 is in the vicinity of the maximum angle can be improved, the detection accuracy of the rotation angle of the throttle valve 1 can be improved.
Moreover, the retaining pieces 31, each having a smaller width than that of both magnetically sensitive faces of the Hall IC 7, are respectively provided for the pair of yokes 6. The respective retaining pieces 31 of the pair of yokes 6 are
provided so as to be opposed to each other through the magnetic detection gap 9 while being in contact with both magnetically sensitive faces of the Hall IC 7. This can concentrate the magnetic flux on both the magnetically sensitive faces of the Hall IC 7. As a result, since the magnetic flux can be concentrated on both magnetically sensitive faces of the Hall IC 7 effectively over the range of a rotation angle in which the thin-plate magnet 4 rotates from the minimum angle to the maximum angle with the rotation of the throttle valve 1, that is, over a full range of the detected angle of the throttle valve 1, a stable output voltage can be obtained from the Hall IC 7.
As a result, the positional accuracy (combination accuracy) of the pair of yokes 6 and the Hall IC 7 with respect to the magnetization direction of the thin-plate magnet 4 can be easily obtained, thereby reducing a variation in assembly of the thin-plate magnet 4 and the pair of yokes 6 and the Hall IC 7. Moreover, since a variation in output from the Hall IC 7 is unlikely to occur, the detection accuracy of the rotation angle of the thin-plate magnet 4 rotating with the rotation of the throttle valve 1 can be prevented from being lowered. Moreover, since the single thin-plate magnet 4 is provided as a magnetic field source, the number of components and the number of assembly steps can be reduced as compared with those of the conventional techniques requiring two magnets. As a result, the overall cost of the
rotation angle detecting device can be reduced.
In the embodiments, the accelerator lever 15 mechanically connected to the throttle lever through a wire cable is attached to one end of the throttle shaft 2 so that the rotation angle detecting device of the present invention is incorporated into the inlet throttle device for internal combustion engine, for transmitting the amount of operation of the accelerator by a driver to the throttle valve 1. However, the rotation angle detecting device of the present invention may be incorporated into a throttle control device for internal combustion engine, for transmitting rotational motive power of a driving motor (an actuator) through a motive power transmission device such as a gear reduction device to the throttle shaft 2 so as to control the rotation angle (the valve opening) of the throttle valve 1 in accordance with the amount of operation of the accelerator by the driver. In this case, a valve gear integrally formed with one end of the throttle shaft 2 is provided in place of the accelerator lever 15 attached to one end of the throttle shaft 2. In this manner, the amount of operation of the accelerator by the driver (for example, the amount of operation of the throttle lever or the amount of pressing on an accelerator pedal) can also be transmitted to the
throttle valve 1.
Moreover, as a resin material for resin integral molding of the throttle body 3, a resin composite material obtained by mixing a filler (for example, a glass fiber at low cost, a carbon fiber, an aramide fiber, a boron fiber or the like) or an additive with a resin material heated to a molten state (for example, a molten resin composed of a thermoplastic resin) (for example, polybutylene terephthalate containing a glass fiber at 30%: PBTG30, or polybutylene terephthalate containing a glass fiber at 40%: PBTG40) may also be used. Moreover, the above-described resin composite material may be injected into a cavity of a mold for resin molding from a gate so as to fabricate a resin throttle body by the injection molding of the resin composite material. The resin molded product obtained by resin integral molding through the injection molding of the resin composite material in this manner is provided at low cost and is excellent in resin moldability, and has improved performance including a mechanical
property, strength, stiffness, heat resistance and the like. Furthermore, in the embodiments, although the resin material (for example, a molten resin composed of a thermoplastic resin) is used as a molten material heated to a molten state is used, a molten metal material (for example, a semi-molten alloy material such as an aluminum alloy) may also be used as a molten material heated to a molten state.
In the embodiments, the example where the Hall IC 7 obtained by integrating the Hall element (a non-contact magnetic detection element) and the amplifier circuit is used as a non-contact magnetic detection element has been described. However, as the non-contact magnetic detection element, a Hall element may be solely used or a magneto-resistance element may be used. Moreover, although the example where the non-contact rotation angle sensor including the pair of yokes (magnetic members) 6 and the Hall IC 7 is used as the throttle opening sensor (the rotation
angle sensor) has been described, a non-contact rotation angle sensor including a stator core (a magnetic member) and a magnetic detection element may also be used as the throttle opening sensor (the rotation angle sensor). Moreover, the magnet such as the planar or columnar thin-plate magnet 4 may be assembled to a rotor core connected to a rotating shaft such as the throttle shaft 2.
1. A rotation angle detecting device for detecting a rotational angle of an object, comprising:
a magnet (4) that rotates with the object, the magnet (4) including two ends magnetized to have opposite polarities;
a magnetic substance unit (5) forming an air gap with the two ends of the magnet (4), the magnetic substance unit (5) including magnetic members (6) disposed substantially symmetrically relative to a vertical plane perpendicularly through a rotational axis of the magnet (4) and defining a magnetic detection gap (9) therebetween; and
a non-contact magnetic detection element (7) disposed in the magnetic detection gap (9) between the magnetic members (6) for outputting a signal corresponding to a density of a magnetic flux passing through the magnetic detection gap (9),
wherein a rotation angle of the object is detected based on the signal output from the magnetic detection element (7), and
the magnetic members (6) each include a reverse warp part (34) so that the air gap suddenly increases when the magnet (4) rotates to a predetermined rotation angle from a state where the air gap is minimum in a direction in which the air gap increases.
2. The rotation angle detecting device according to claim 1, wherein the reverse warp parts (34) are provided so that parts extended from reference positions to both sides are curved in an approximately circular arc shape,
the reference positions defining the minimum air gap.
3.	The rotation angle detecting device according to claim 1 or 2, further
a housing (3) integrally formed of a non-magnetic material and including a sensor retaining section (23) and a magnet holding hole (20),
the sensor retaining section (23) for retaining a rotation angle sensor including the magnetic members (6) and the magnetic detection element (7), and
the magnet holding hole (20) for holding the magnet (4) therein such that the magnet (4) can rotate freely.
4.	The rotation angle detecting device according to any one of claims 1 to 3,
the magnetic detection element (7) has magnetically sensitive faces having a certain width on opposing sides in a plate-thickness direction, and
the magnetic detection gap (9) is provided in a middle of a magnetic circuit including the magnet (4) and the magnetic members (6) so that a positional relation is such that a density of a magnetic flux crossing both the magnetically sensitive faces of the magnetic detection element (7) in the plate-thickness direction with respect to a magnetization direction of the magnet (4) becomes relatively small when the rotation angle of the object is positioned in a middle angle within a range of use.
5.	The rotation angle detecting device according to any one of claims 1 to 4,
the magnetic detection element (7) has magnetically sensitive faces having a
certain width on opposing sides in a plate-thickness direction,
the magnetic members (6) have magnetic detection element retaining pieces (31) having a smaller plate width than that of the reverse warp parts (34), respectively, and
the respective magnetic detection element retaining pieces (31) of the magnetic members (6) oppose each other through the magnetic detection gap (9) while contacting the magnetically sensitive faces of the magnetic detection element (7) in the plate-thickness direction.
6. The rotation angle detecting device according to claim 5, wherein the magnetic members (6) each include a shoulder part (32) extended in a direction approximately perpendicularly crossing a center axis direction so as to be separated away from each other in an approximately straight manner, and a bent part (35) bent at an approximately acute angle at an end of the shoulder part (32) so as to be connected to the reverse warp part (34), and
the respective magnetic detection element retaining pieces (31) of the magnetic members (6) are provided so as to be bent at an approximately right angle at ends of the shoulder parts (32) on the magnetic detection gap side so as to be separated away from the magnet (4).
0667-che-2005-abstract.pdf
0667-che-2005-claims.pdf
0667-che-2005-correspondnece-others.pdf
0667-che-2005-description(complete).pdf
0667-che-2005-drawings.pdf
0667-che-2005-form 1.pdf
0667-che-2005-form 26.pdf
0667-che-2005-form 3.pdf
0667-che-2005-form 5.pdf
0667-che-2005-others.pdf
667-che-2005 claims-22-07-2009.pdf
667-che-2005 correspondance others.pdf
667-che-2005 correspondence others-22-07-2009.pdf
667-che-2005 form-3-22-07-2009.pdf
667-che-2005 pct.pdf
667-che-2005 petiition-22-07-2009.pdf
667/CHE/2005
1-1, SHOWA-CHO KARIYA-CITY AICHI-PREF 448-8661 JAPAN.
1 NAKANO, YUJI C/O DENSO CORPORATION 1-1, SHOWA-CHO KARIYA-CITY AICHI-PREF 448-8661 JAPAN.
2 SANO, RYO C/O DENSO CORPORATION, 1-1, SHOWA-CHO, KARIYA-CITY,AICHI-PREF 448-8661, JAPAN
3 FURUKAWA, AKIRA C/O DENSO CORPORATION, 1-1, SHOWA-CHO, KARIYA-CITY,AICHI-PREF 448-8661, JAPAN
4 ISHIDA, SHINJI C/O DENSO CORPORATION, 1-1, SHOWA-CHO, KARIYA-CITY,AICHI-PREF 448-8661, JAPAN
1 2004-164974 2004-06-02 Japan