JP2004191300A - Rotation sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized rotation sensor prevented from causing noise in rotation number detection. <P>SOLUTION: This rotation sensor capable of detecting the rotation number of a rotating body is equipped with a rotor gear 21 fixed to the rotating body and the rotation sensor 2 for detecting the rotation number of the rotating body. The rotation number of the rotating body is transmitted to the rotation sensor 2 by interposing at least one transmission gear 11 between the rotation sensor 2 and the rotor gear 21. This prevents the rotor gear 21 rotating with the rotating body from directly engaging with the rotation sensor 2 detecting the rotation number of the rotating body. A small-sized rotation sensor 1 can be obtained which is prevented from causing noise in rotation number detection. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation sensor used for detecting a rotation angle in a steering of an automobile, for example.
[0002]
[Prior art]
For example, a rotation sensor may be attached to a steering wheel of an automobile to detect a rotation angle of the steering wheel (for example, see Patent Document 1). Such a rotation sensor includes a rotor and a stator, and the rotor rotates integrally with the steering. On the other hand, the stator is fixed to a combination switch bracket or the like via a case, and the relative rotation between the rotor and the stator depends on the steering angle of the steering. The rotation angle is changed.
[0003]
Further, the rotor has a rotor sensing unit for detecting the rotation angle of the rotor. The rotor sensing unit is formed of a ring member made of a conductive material such as iron and having a variable width in the circumferential direction. On the other hand, a coil housed in a magnetic material core is arranged on the stator so as to face the rotor ring member. Then, by rotating the ring member, the degree of generation of the eddy current is converted into a change in coil impedance, which is detected and taken out as a rotation angle signal.
[0004]
Note that the steering is generally rotated from −900 ° to + 900 °, that is, five rotations (two and a half turns to the left and two and a half turns to the right) in terms of the structure of the vehicle. The number is also detected, and the steering angle (absolute rotation angle) of the steering in the rotation range of -900 ° to + 900 ° can be detected.
[0005]
A rotation speed sensor is used to detect the steering rotation speed. The rotation speed sensor has a Geneva gear that feeds teeth every time the rotor rotates a predetermined amount. Further, the Geneva gear is provided with a conductive ring member whose width changes stepwise in the circumferential direction, and an AC magnetic field is applied to a part of the ring member to form a vortex corresponding to the rotation angle of the ring member. Generating current. Then, the degree of occurrence of the eddy current is converted into a change in coil impedance, which is detected and taken out as a steering speed signal.
[0006]
[Patent Document 1]
JP-A-2002-098506 (pages 4 to 6, FIG. 1)
[Problems to be solved by the invention]
When the above-mentioned rotation speed sensor is configured using a Geneva gear (malta cloth) generally used in the related art, it is necessary to provide a tooth feed pin of the Geneva gear on the outer periphery of the rotor. It is necessary to arrange a Geneva gear having a size and shape smoothly intermittently fed by the pins around the rotor. FIG. 6 shows a partial configuration of a rotation sensor 5 having the structure according to FIG.
[0007]
When the rotation speed sensor is configured using the Geneva gear that satisfies the functional requirements as described above, the rotation sensor 5 itself becomes large in the radial direction as shown in FIG. (See the comparison between the steering shaft radius RS shown in FIG. 6 and the case radius R1 from the center 5C of the rotation sensor 5 to the outer periphery of the case 51).
[0008]
For example, when detecting the steering angle (absolute rotation angle) of a steering using a rotation sensor, the rotation sensor must be provided near the steering wheel, and such a large-sized rotation sensor 5 is mounted near the steering wheel. If this is done, it will be an obstacle to operation during steering operation, which is not preferable.
[0009]
On the other hand, it is also conceivable to reduce the size of the rotation sensor itself by changing the design of the Geneva gear itself to an intermittent gear having a special shape as shown in FIG. 7 and reducing the size of the rotation sensor in the radial direction.
[0010]
The rotation sensor 6 has an intermittent gear 64, and the intermittent gear 64 has a plate-like shape provided with a plurality of (six in FIG. 7) arc-shaped sliding concave portions 64 c that slide along the outer peripheral surface of the rotor 63. And a gear portion 64b formed on one surface of the base portion 64a. The Geneva dog 63b provided at a predetermined position on the outer peripheral portion of the rotor 63 intermittently interlocks the gear portion 64b located on the outer peripheral portion of the rotor. By flicking, the gear portion 64b is intermittently fed.
[0011]
In addition, a conductive ring member (not shown) whose width is gradually changed in the circumferential direction is provided on the side surface of the base portion 64a (not shown) opposite to the gear forming surface, and this ring member is similar to the above-described conventional example. The AC magnetic field is applied locally from the coil. Then, the degree of occurrence of the eddy current in the ring member is changed to a change in the coil impedance, which is detected and taken out as a steering speed signal.
[0012]
As can be seen from FIG. 7, the rotation sensor 6 can be obviously reduced in size compared with the rotation sensor 5 shown in FIG. 6 described above (the radius RS of the steering shaft S and the center of the rotation sensor 6 shown in FIG. 7). (See case radius R2 from 6C to the case periphery).
[0013]
However, when the rotation sensor is configured in this manner, a considerable collision sound is generated when the Geneva dog 63b of the rotor 63 hits and repels the gear portion 64b.
[0014]
This has a structure in which the rotation sensor 6 directly transmits rotation from the large-diameter rotor 63 to the small-diameter intermittent gear 64, and has a gear portion 64b of the intermittent gear 64 in the same manner as a normal meshing state of gears. This is because the approach angle of the Geneva dog 63b becomes close to 90 °. Further, when feeding the intermittent gear 64, the protrusion between the sliding concave portions 64a of the intermittent gear 64 may hit the rotor 63 to generate an impact sound.
[0015]
If it is attempted to detect the rotational speed of the steering using such a rotation sensor 6, the above-mentioned hit sound will be generated intermittently every time the steering is rotated. Since the rotation sensor 6 must be provided in the vicinity of the steering wheel due to its function, the generation of such a sound at the time of steering operation gives a driver discomfort. Since the steering wheel makes a total of five rotations in the rotation range of -900 ° to + 900 °, especially when the steering wheel is rotated many times, such a contact sound is continuously generated, which is not preferable.
[0016]
An object of the present invention is to provide a rotation sensor that is small and does not emit noise when detecting the number of rotations.
[0017]
[Means for Solving the Problems]
In order to solve the above-described problems, a rotation sensor according to the present invention includes a rotor gear fixed to a rotating body and a rotation speed sensor that detects a rotation speed of the rotating body, and at least a rotation sensor and the rotor gear The rotation of the rotating body is transmitted to the rotation speed sensor through one transmission gear.
[0018]
Since the rotor gear that rotates with the rotating body and the rotation sensor that detects the number of rotations of the rotating body do not directly mesh with each other and at least one transmission gear is interposed therebetween, the rotation is transmitted from the rotating body to the rotation sensor. Is performed smoothly. Therefore, unlike the conventional case, the rotor gear that rotates together with the rotating body does not emit the repulsion sound between the teeth, which is generated when the rotation is directly transmitted to the rotation sensor, so that the rotation sensor can be reduced in noise.
[0019]
In addition, if the rotor gear rotating with the rotating body and the rotation sensor for detecting the number of rotations of the rotating body are directly engaged with each other to reduce the sound of the tooth repulsion, the rotation sensor itself becomes large, but the transmission sensor becomes larger through the transmission gear. Since the rotation of the rotating body is transmitted to the rotation sensor, such an increase in the size of the rotation sensor itself can be avoided.
[0020]
According to a second aspect of the present invention, in the rotation sensor according to the first aspect, the rotation speed sensor includes a Geneva gear, and a gear diameter of the transmission gear meshing with the Geneva gear is larger than a gear diameter of the rotor gear. Is also small and approximates the gear diameter of the Geneva gear.
[0021]
Since the diameter of the Geneva gear and the transmission gear meshing with it are similar, the transmission of the rotation from the transmission gear to the Geneva gear generates a rebound sound by the Geneva dog of the transmission gear smoothly entering the slit of the Geneva gear. It is done smoothly without doing. Further, since the diameter of the transmission gear is smaller than the diameter of the rotor gear, the size of the rotation sensor itself in the radial direction can be reduced, and the size of the rotation sensor itself can be reduced.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a rotation sensor 1 according to an embodiment of the present invention will be described.
[0023]
The following embodiment will be described on the assumption that a steering angle of a vehicle is detected using the rotation sensor 1 according to an embodiment of the present invention.
[0024]
A rotation sensor 1 according to an embodiment of the present invention includes a rotor 20 that rotates together with a steering shaft S as shown in FIGS. 1 and 2, a stator 30 fixed to a combination switch bracket (not shown) or the like via a case 10. It has. Then, the relative rotation angle between the rotor 20 and the stator 30 changes within a rotation range of -900 ° to + 900 ° of the steering.
[0025]
The rotor 20 includes a rotor sensing unit 25. The rotor sensing unit 25 is a ring member made of a conductive member such as iron and having a variable width in the circumferential direction. On the other hand, coils 35 and 15 housed in a magnetic material core are provided on the stator 30 so as to be opposed to the ring member of the rotor sensing unit 25, and the degree of eddy current generation is reduced by rotating the ring member. This is converted into a change in impedance, detected, and taken out as an angle signal. This makes it possible to periodically detect the rotation angle every time the steering rotates 360 °.
[0026]
As shown in FIGS. 1 and 2, the rotor 20 includes a rotor gear 21 integrated with the rotor 20, a transmission gear 11 meshed with the rotor gear 21, and a Geneva gear 12 intermittently rotated by the transmission gear 11. Equipped. The Geneva gear 12 serves as a rotation speed sensor 2 (see FIG. 2) for detecting the rotation speed of the steering. That is, the Geneva gear 12 used as the rotation speed sensor 2 is configured such that the gear is fed by one pitch every fixed rotation of the rotor 20. The Geneva gear 12 is provided with a ring-shaped copper foil plate having a stepwise different width (not shown). Thus, the Geneva gear 12 is intermittently fed each time the steering wheel rotates by a predetermined angle, and the width of the copper foil plate changes. Further, the detection coil 36 is arranged near the copper foil plate so that an AC magnetic field is locally applied to the copper foil plate, and the width of the copper foil plate at the portion where the AC magnetic field is applied changes every time the steering rotates a predetermined amount. Then, the degree of occurrence of the eddy current generated in response thereto is converted into a change in coil impedance and detected. As a result, different signals are output stepwise within the steering rotation range of -900 ° to + 900 °, and the steering rotation speed can be detected.
[0027]
The transmission gear 11 interposed between the rotor gear 21 and the Geneva gear 12 is formed with a gear portion 11a meshing with the rotor gear 21 at the outer periphery thereof, and a C-shaped member slidable with the peripheral surface of the Geneva gear 12 at the center. Is formed. Further, a pin-shaped Geneva dog 11c for intermittently feeding the Geneva gear 12 is formed in the vicinity of the notch portion of the convex sliding portion 11b of the transmission gear 11 so as to protrude. The Geneva dog 11 c moves around the axis of the transmission gear 11 with the rotation of the transmission gear 11.
[0028]
The gear diameter of the transmission gear 11 is smaller than the gear diameter of the rotor gear 21, and the transmission gear 11 is a speed increasing gear with respect to the rotor gear 21. Further, the gear diameter of the transmission gear 11 and the gear diameter of the Geneva gear 12 are substantially equal, so that the tangential direction of the movement trajectory of the Geneva dog 11c and the direction in which the slit 12s of the Geneva gear 12 is formed are quite close.
[0029]
This point will be described in more detail with reference to FIG. 3. When the Geneva dog 11 c enters the slit 12 s of the Geneva gear 12, the angle of approach is very close to the direction in which the Geneva gear 12 is formed (the difference between the two angles is only the angle α). ), The Geneva dog 11c enters the slit 12s. After the Geneva dog 11c enters the slit 12s of the Geneva gear 12, the Geneva dog 11c moves in a direction in which the Geneva gear 12 is intermittently fed. Thereby, it is possible to prevent the generation of a hitting sound between the gears during the intermittent feeding of the Geneva gear 12. Further, since the gear diameters of the transmission gear 11 and the Geneva gear 12 are smaller than the gear diameter of the rotor gear 21, the radial size of the rotation sensor itself is much smaller than that of the conventional rotation sensor 5 shown in FIG. (See the radius RS of the steering shaft S and the case radius R3 from the center 1C of the rotation sensor 1 to the outer periphery of the case shown in FIG. 2).
[0030]
Next, the operation of the rotation sensor 1 in the above embodiment will be described.
[0031]
4 and 5 are views showing a state where the Geneva gear 12 is intermittently fed as the rotor 20 rotates. In the figure, a fitting hole for the steering shaft S in the rotor 20 is not shown.
[0032]
FIG. 4A shows the initial state in this description, and FIG. 4B shows that the rotor gear 21 rotates by 75 ° from FIG. 4A and the transmission gear 11 rotates by 120 ° in response to this, and the Geneva dog 11c becomes The state immediately before entering the slit 12s of the Geneva gear 12 is shown.
[0033]
As can be seen from this figure, the advancing direction of the Geneva dog 11c and the formation direction of the slit 12s of the Geneva gear 12 substantially coincide with each other at this time, and it can be seen that the Geneva dog 11c can smoothly enter the slit 12s.
[0034]
Next, as shown in FIG. 4C, when the rotor gear 21 rotates 93.75 ° from the initial state, the transmission gear 11 rotates 150 ° from the initial state, the Geneva dog 11c enters the slit 12s of the Geneva gear 12, and the Geneva gear 12 Has begun to intermittently feed.
[0035]
Subsequently, as shown in FIG. 5A, when the rotor gear 21 rotates 112.5 ° from the initial state, the transmission gear 11 rotates 180 ° in response thereto, and the Geneva dog 11c is inserted into the slit 12s of the Geneva gear 12 as far as it will go. Enter completely.
[0036]
Further, as shown in FIG. 5B, when the rotor gear 21 rotates 131.25 ° from the initial state, the transmission gear 11 rotates 210 ° accordingly, and the Geneva dog 11c moves slightly from the depth of the slit of the Geneva gear 12. .
[0037]
Then, as shown in FIG. 5C, when the rotor gear rotates 150 ° from the initial state, the transmission gear 11 rotates 240 ° accordingly, and the Geneva dog 11c escapes from the slit 12s of the Geneva gear 12. As is apparent from this figure, the direction in which the Geneva dog 11c escapes and the direction in which the slit 12s of the Geneva gear 12 is formed substantially coincide with each other at this time, and the Geneva dog 11c can smoothly escape from the slit 12s.
[0038]
That is, as can be seen from these figures, the Geneva dog 11c of the transmission gear 11 easily enters the slit 12s of the Geneva gear 12 by passing through the transmission gear 11, and the Geneva dog 11c escapes smoothly from the slit 12s of the Geneva gear 12. Therefore, the Geneva gear 12 can be smoothly and intermittently driven. As a result, it can be seen that the Geneva gear 12 is intermittently fed via the transmission gear 11 without generating a contact sound between the teeth.
[0039]
Therefore, it is possible to provide the rotation sensor 1 which does not generate the repelling sound seen in the conventional rotation sensor 6 when rotating the Geneva gear 12 and reduces the noise.
[0040]
In addition, by interposing the transmission gear 11 having a smaller diameter than the rotor gear 21, it is necessary to adopt a structure in which the rotor gear rotating together with the steering and the Geneva gear for detecting the number of rotations of the steering are directly meshed with each other to reduce the repulsion sound between the teeth. Absent. Therefore, the size of the rotation sensor 1 in the radial direction can be reduced, and the size of the entire rotation sensor can be reduced.
[0041]
In addition, since a commonly used Geneva gear can be used, it is not necessary to specially design a specially shaped Geneva gear according to the shape of the rotor gear, and a cost-effective rotation sensor can be provided.
[0042]
In the above embodiment, the number of transmission gears is one. However, the number of transmission gears is not limited to one, and two or more transmission gears may be interposed between the rotor gear and the Geneva gear.
[0043]
Further, the rotation sensor described above is not limited to detection of a steering rotation angle of a vehicle, but can be suitably used for any rotating body that needs to detect a rotation angle. However, if it is used for detecting the rotation angle of a part that is not preferable to generate noise during rotation, such as for detecting the steering rotation angle of the vehicle, and that requires a reduction in the size of the rotation sensor itself, The effect can be fully exhibited.
[0044]
【The invention's effect】
As described above, in the rotation sensor according to the present invention, the rotor gear that rotates together with the rotating body and the rotation sensor that detects the number of rotations of the rotating body do not directly mesh with each other, and at least one transmission gear is interposed therebetween. The rotation is smoothly transmitted from the rotating body to the rotation sensor. Therefore, unlike the conventional case, the rotor gear that rotates together with the rotating body does not emit the repulsion sound between the teeth that occurs when the rotation is directly transmitted to the rotation sensor, and the rotation sensor can have a low noise.
[0045]
Also, if the rotor gear rotating with the rotating body and the rotation sensor for detecting the number of rotations of the rotating body are directly meshed with each other to reduce the sound of tooth rebound, the rotation sensor itself becomes large, but the transmission Since the rotation of the rotating body is transmitted to the rotation sensor, it is possible to avoid such an increase in the size of the rotation sensor itself.
[0046]
Further, in the rotation sensor according to claim 2 of the present invention, since the diameter of the Geneva gear and the transmission gear meshing therewith are close to each other, the Geneva dog of the transmission gear smoothly enters the slit of the Geneva gear, The transmission of the rotation from the transmission gear to the Geneva gear is performed smoothly without generating a popping sound. Further, since the diameter of the transmission gear is smaller than the diameter of the rotor gear, the size of the rotation sensor itself in the radial direction can be reduced, and the size of the rotation sensor itself can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a state in which a rotation sensor according to an embodiment of the present invention is mounted on a steering shaft of a vehicle.
FIG. 2 is a schematic view partially showing the structure of the rotation sensor of FIG. 1;
FIG. 3 is a partially enlarged view showing a state when the Geneva gear of the rotation sensor shown in FIG. 2 is intermittently fed.
4 (a) to 4 (c) show the relationship between a transmission gear and a Geneva gear when the rotor of the rotation sensor shown in FIG. 2 is gradually rotated.
5 is a diagram showing the relationship between the transmission gear and the Geneva gear when the rotor of the rotation sensor shown in FIG. 2 is gradually rotated following FIG. 4 in the order of FIG. 5A to FIG. 5C; It is.
FIG. 6 is a schematic view partially showing the structure of a conventional rotation sensor.
FIG. 7 is a schematic view partially showing the structure of another conventional rotation sensor.
[Explanation of symbols]
Reference Signs List 1 rotation sensor 2 rotation number sensor 5 rotation sensor 5C center 6 rotation sensor 11 transmission gear 11a gear part 11b concave sliding part 11c Geneva dog 12 Geneva gear 15 Coil 12s Slit 20 Rotor 21 Rotor gear 25 Rotor sensing part 30 Stator 35 Coil 36 Detection coil 51 Case 63 Rotor 63b Geneva dog 64 Intermittent gear 64a Base 64b Gear 64c Sliding recess R1-R3 Case radius RS Steering shaft radius S Steering shaft

Claims (2)

A rotor gear fixed to the rotating body,
A rotation speed sensor for detecting the rotation speed of the rotating body,
A rotation sensor for transmitting rotation of a rotating body to a rotation speed sensor with at least one transmission gear interposed between the rotation speed sensor and a rotor gear. The said rotation speed sensor is provided with a Geneva gear, The gear diameter of the said transmission gear meshing with the said Geneva gear is smaller than the gear diameter of the said rotor gear, and the gear diameter of the said Geneva gear is characterized by the above-mentioned. 2. The rotation sensor according to 1.

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