JP6626476B2 - Rotation angle detection device using gear support mechanism to hold gear in proper position - Google Patents

Description

  The present invention relates to a mechanism for supporting a gear used in a rotation angle detecting device, and more particularly, to a rotation angle detecting device using a gear supporting mechanism for holding a gear at an appropriate position.

  In order to accurately detect the rotation of the gear, it is essential that the shaft on which the gear is mounted is stable with respect to the rotation of the gear. In order to secure the stability of the shaft, a multi-rotation absolute rotation angle detection device disclosed in Japanese Patent Application Laid-Open No. 2012-145380 (Patent Document 1), as shown in FIG. A holding plate 32 for holding the second to fourth rotation shafts 24 to 26 to which b, 26a, and b are respectively fixed is used. By the holding plate 32, the central axes of the second to fourth rotation shafts 24 to 26 are stabilized without rotation against rotation of the gears 24a, b, 25a, b, 26a, b.

  Further, the rotation angle detection device 1 disclosed in Japanese Patent Application Laid-Open No. 2004-354075 (Patent Document 2) discloses a structure in which a second gear 3 made of resin is sandwiched between a circuit board 2 and a lower case 10.

  Further, Japanese Patent Application Laid-Open No. 2013-152092 (Patent Document 3) discloses a multi-rotation module in which gears 302 and 303 subordinate to a gear 301 are supported by bearings 303 and 304, respectively. The gear is supported and held at one point by 303 and 304.

JP 2012-145380 A JP-A-2004-354075 JP 2013-152092 A

  In the case of the structure shown in FIG. 2 of Patent Document 1, the components that hold the rotating shaft of the gear at both ends are separate components, so it is difficult to maintain the coaxiality accuracy of the gear bearing during assembly. A holding plate for holding the rotating shaft is required.

  The structure shown in FIG. 1 of Patent Document 2 is used for a rotation angle detection device that detects a steering angle of a vehicle, and therefore has a low rotation speed of a gear, so that there is no problem in the detection accuracy of the rotation angle. However, when the gear rotates at high speed, when the resin gear is held by the resin material, when the sliding speed of the sliding portion increases, the resin material is melted by frictional heat. For this reason, this structure cannot be applied to high-speed rotation applications. To prevent this, a countermeasure to make the gears made of metal is conceivable. However, if gears of the same shape are made of metal, the cost increases. Further, since the metal gear is a conductor, there is a risk that a short circuit may occur on the circuit board due to abrasion powder.

  In the case of the structure shown in FIG. 4 of Patent Document 3, it is necessary to fix the gear to a bearing fixed to the base component in order to fix the gear in the axial direction. Therefore, it is necessary to use a bearing such as a deep groove ball bearing, which has parts separated into a part (outer ring) fixed to the base part and a part (inner ring) fixed to the gear, such as a deep groove ball bearing. Since a deep groove ball bearing or the like is used, it is difficult to reduce costs. Also, if the gear shaft is tilted due to the effect of the bearing internal clearance, etc., it will not be possible to properly engage the gear, or the position of the magnet installed on the gear will shift in the radial direction, affecting the sensor detection accuracy. Can be considered.

  The present invention has been made in view of such a conventional problem, and a gear that constitutes a gear mechanism for detecting a rotation angle of a main rotation shaft is fixed to a housing that houses the gear mechanism. It is configured to be held by the shaft and held between two surfaces of the housing, and a circuit board as a part of the housing is used for a portion where the gear is held between the surfaces. Further, a resin material is used for the gear, and a metal shaft is used for the gear shaft. The gear is rotatably in direct contact with the circuit board. In addition, the end face of the gear protrudes by an appropriate amount from the end face of the built-in magnet, and the distance between the magnet and the magnetic detection element is appropriately maintained by the amount of protrusion, and the magnet and the circuit board slide directly. The above problem can be solved by adopting a structure that prevents the above. Hereinafter, the present invention will be described with reference to the drawings.

ADVANTAGE OF THE INVENTION According to this invention, the slidability of the gear with respect to a housing | casing can be improved by producing a gear and a housing | casing from a different material, and it can be adapted to high-speed rotation. In addition, since the gears can be rotated by directly contacting the circuit board and the housing, a gear mechanism with a reduced number of components can be realized, and an inexpensive and small rotation angle detection device can be realized. At the same time, the frictional heat generated in the gear can be conducted from the gear shaft to the housing, thereby preventing the gear from melting .

FIG. 3 is a cross-sectional view of a rotation angle detection device using the gear support mechanism of the present invention. It is a three-dimensional exploded view of another rotation angle detecting device using the gear support mechanism of the present invention.

  A rotation angle detection device according to the present invention is a device that detects a rotation angle of a rotation shaft, and includes a gear mechanism configured by a plurality of gears meshed with each other. By detecting the rotation angle of each gear, it is possible to detect a multi-rotation absolute (absolute) rotation angle of the rotation shaft input to the rotation angle detection device. FIG. 1 is a cross-sectional view of such a rotation angle detection device 100. The main rotation shaft 101 of the rotation angle detection device 100 is coupled to an output rotation shaft of a motor (not shown) and serves as an input of the rotation angle detection device 100. That is, the rotation angle detection device 100 can detect a multiple rotation absolute rotation angle of the motor output rotation shaft.

  The main shaft gear 102 fixed to the main rotation shaft 101 is engaged with the sub gear 103, and transmits the rotation of the main shaft gear 102 to the sub gear 103. The slave gear 103 is inserted into a gear shaft 105 fixed to a housing 104 of the rotation angle detection device 100, and freely rotates around the gear shaft 105. A magnet 106 is attached to the tip of the main rotating shaft 101, and the magnet 106 rotates with the rotation of the main shaft gear 102. The magnet 106 is an annular magnet in which a plurality of S poles and N poles serving as magnetic poles are alternately arranged. Further, the magnet 108 is incorporated in the slave gear 103, and the magnet 108 rotates with the rotation of the slave gear 103. As shown in FIG. 1, a subordinate gear 103 may be provided with a cylindrical storage container 107 integrally formed with the subordinate gear 103, and a magnet 108 may be built therein.

  A magnetic detection element 109 such as an MR sensor is mounted on the circuit board 110 at a position facing the tip of the main rotating shaft 101, and the magnetic detection element 109 detects a change in a magnetic field caused by rotation of the magnet 106. A magnetic detection element 111 such as an MR sensor is mounted on the circuit board 110 at a position facing the magnet 108, and the magnetic detection element 111 detects a change in a magnetic field caused by the rotation of the magnet 108. The change in the magnetic field detected by the magnetic detection elements 109 and 111 is output as a magnetic detection signal to a magnetic detection circuit (not shown) arranged on the circuit board 110, and the multi-rotation absolute of the main rotary shaft 101 is performed by a predetermined calculation. Calculate the rotation angle. The main shaft gear 102, the subordinate gear 103, the magnets 106 and 108, and the magnetic detection elements 109 and 111 constitute an absolute magnetic encoder 112 together with a magnetic detection circuit.

  As described above, the slave gear 103 rotates around the gear shaft 105 by the rotation of the main shaft gear 102. However, depending on the direction in which the rotation angle detection device 100 is installed, the gravity applied to the slave gear 103 or the main shaft gear A force is generated in the axial direction of the gear shaft 105 due to the meshing reaction force with the gear shaft 105. This force causes the dependent gear 103 to move in the axial direction of the gear shaft 105. However, as described below, the dependent gear 103 is supported by the housing 104 and the circuit board 110 while maintaining an appropriate gap. The proper position can be maintained.

  When the slave gear 103 rotates due to the rotation of the main shaft gear 102, frictional heat is generated between the slave gear 103 and the gear shaft 105 and between the slave gear 103 and the housing 104 in the sliding portion 103a. The friction heat can be easily transmitted to the housing 104 by using the metal gear shaft 105, so that the slave gear 103 can be prevented from being melted by the friction heat. Further, by manufacturing the gear shaft 105 from bearing steel that easily obtains high hardness, for example, high carbon chromium bearing steel, wear resistance and high rigidity can be ensured.

  The main shaft gear 102 and the slave gear 103 are made of a polyacetal-based resin having no water absorption / swelling properties, excellent dimensional stability, and excellent lubricity, and a backlash, which is play between gears, is maintained. You. Further, in selecting a material for the casing 104 that slides with the dependent gear 103, as a result of examining various combinations of materials, it has been determined that the casing 104 is made of a material different from the dependent gear 103. It has been found that the slidability between the housings 104 can be improved. Therefore, the housing 104 of the rotation angle detecting device 100 employs a resin having polyphenyl sulfide as a base material having excellent strength and rigidity. However, as long as the material has excellent strength and rigidity, another resin material can be used as long as the material is different from that of the dependent gear 103.

  The slave gear 103 is supported by the circuit board 110 while maintaining an appropriate gap. In order to enhance the slidability of the dependent gear 103, a sliding plate 113 is inserted into a gap between the dependent gear 103 and the circuit board 110. In order to enhance the slidability, the sliding plate 113 is made of a material different from the material of the dependent gear 103, similarly to the case where the casing 104 is made of a material different from that of the dependent gear 103. As the sliding plate 113, a resin material of a nylon base material having excellent slidability is used, and for example, a polyslider may be used. By using the sliding plate 113, even if the surface state of the circuit board 110 changes due to the difference between the manufacturing lot and the manufacturer of the circuit board 110, the lubrication state between the dependent gear 103 and the circuit board 110 is reduced. No change occurs, and the dependent gear 103 can be rotated stably. Further, by reducing the area of the sliding portion of the sliding plate 113 as much as possible, the generation of frictional heat between the dependent gear 103 and the circuit board 110 can be suppressed. In addition, even if the slave gear 103 is in direct contact with the sliding part of the circuit board 110, if it is confirmed that there is no problem in the durability of the sliding part of the circuit board 110, the sliding between the slave gear 103 and the circuit board 110 is possible. There is no need to insert the moving plate 113.

  The upper end surface 107a of the storage container 107 protrudes by an appropriate amount from the upper end surface 108a of the built-in magnet 108, and the distance between the magnet 108 and the magnetic detection element 111 is appropriately maintained by the amount of protrusion, and It is possible to prevent the upper end surface 108a from sliding directly on the sliding plate 113.

  FIG. 2 is a three-dimensional exploded view of another rotation angle detecting device 200 having a gear mechanism in which two series-connected slave gears are further added to the main rotation shaft 101 of the gear mechanism shown in FIG. 2, the same reference numerals indicate the same or similar elements as those in FIG. The gear mechanism composed of the main shaft gear 102 fixed to the main rotation shaft 101 and the subordinate gear 103 has the same configuration as that of FIG.

  In FIG. 2, a main rotation shaft 101 is coupled to an output rotation shaft of a motor main body 201. The main shaft gear 102 fixed to the main rotation shaft 101 meshes with a first dependent gear 203a inserted into a gear shaft 202 fixed to the housing 104, and the first driven gear 203a Rotate freely as center. The first subsidiary gear 203a is integrally formed with a second subsidiary gear 203b having a number of teeth different from the number of teeth of the first subsidiary gear 203a. Above the second dependent gear 203b, a cylindrical storage container 204 is integrally formed with the first and second dependent gears 203a and 203b, and a magnet 205 is built in the storage container 204. The centers of the main rotation shaft 101, the magnet 106, and the circuit board 110 are arranged along the center axis X1. Further, the centers of the gear shaft 105, the slave gear 103, and the magnet 108 are arranged along the center axis X2. Further, the centers of the gear shaft 202, the first subsidiary gear 203a, the second subsidiary gear 203b, and the magnet 205 are arranged along the central axis X3.

  The second dependent gear 203b further meshes with a third dependent gear 207 inserted into a second gear shaft 206 fixed to the housing 104, and the third dependent gear 207 is free to rotate about the second gear shaft 206 as an axis. To rotate. Above the third subsidiary gear 207, a cylindrical storage container 208 is integrally formed with the third subsidiary gear 207, and a magnet 209 is built in the storage container 208. With such a gear mechanism, the rotation of the main rotation shaft 101 is transmitted from the main shaft gear 102 to the first subordinate gear 203a, and from the second subordinate gear 203b integrally formed with the first subordinate gear 203a to the third subordinate gear 207. Is transmitted to The centers of the gear shaft 206, the third subsidiary gear 207, and the magnet 109 are arranged along the central axis X4.

  The rotation of the first and third dependent gears 203a and 207 generates frictional heat on the first and second gear shafts 202 and 206. This frictional heat is easily generated because the first and second gear shafts 202 and 206 are made of metal. Thus, similarly to the gear shaft 105, it is possible to prevent the first, second, and third dependent gears 203a, 203b, and 207 from melting due to frictional heat. Further, by producing the first and second gear shafts 202 and 206 from bearing steel that easily obtains high hardness, for example, high carbon chromium bearing steel, wear resistance and high rigidity can be secured. The same is true.

  Similar to the positional relationship between the magnet 108 shown in FIG. 1 and the magnetic detection element 111 disposed at a position facing the magnet 108, the magnetic detection element ( (Not shown). Based on the magnetic detection signals output from these magnetic detection elements, a magnetic detection circuit (not shown) arranged on the circuit board 110 executes a predetermined operation to execute the multi-rotation absolute rotation of the main rotation shaft 101. Calculate the rotation angle.

  As described above with respect to the material of the casing 104, based on the finding that the slidability of the dependent gear 103 can be improved by using different materials for the dependent gear 103 and the casing 104, A material different from the material of the housing 104 is used for the three dependent gears 203a, 203b, and 207. As the material of the first, second, and third dependent gears 203a, 203b, and 207, a resin based on polyacetal is used as in the case of the dependent gear 103. The first, second, and third dependent gears 203a, 203b, and 207 may be made of another resin material as long as the material is different from the material of the housing 104.

  A sliding plate 210 for improving slidability is inserted between the circuit board 110 and the upper end surfaces 204a and 208a of the storage containers 204 and 208. In order to enhance the slidability, a material different from the material of the first, second, and third dependent gears 203a, 203b, and 207 is used for the sliding plate 210. As the sliding plate 210, similarly to the sliding plate 113, a nylon-based resin material having excellent slidability is used, and for example, a polyslider may be used. The sliding plate 210 can stably rotate the first, second, and third dependent gears 203a, 203b, and 207 even when the surface state of the circuit board 110 changes. Further, by reducing the area of the sliding portion of the sliding plate 210 as much as possible, it is possible to suppress the generation of frictional heat between the upper end surfaces 204a and 208a and the sliding plate 210. Even if the upper end surfaces 204a and 208a are brought into direct contact with the circuit board 110, if it is confirmed that there is no problem in the durability of the sliding portion on the circuit board 110, the contact between the upper end surfaces 204a and 208a and the circuit board 110 is possible. It is not necessary to insert the sliding plate 210 in the first position.

  The upper end surfaces 204a, 208a of the storage containers 204, 208 are made to protrude from the upper end surfaces 205a, 209a of the built-in magnets 205, 209 by an appropriate amount of less than 1 mm, so that the magnets 205, 209 It is possible to maintain a proper distance between the magnets 205 and 209 and the opposing magnetic detecting element and prevent the upper end surfaces 205a and 209a of the magnets 205 and 209 from directly sliding on the sliding plate 210.

  As described above, when the gear rotates in contact with the casing, the gear and the casing are made of different materials, so that the gear can be smoothly rotated. , And can be adapted to high-speed rotation. Since the gear can be rotated by directly contacting the housing, a gear mechanism with a reduced number of components can be realized, and a low-cost and small rotation angle detecting device can be realized.

REFERENCE SIGNS LIST 100, 200 rotation angle detection device 101 main rotation shaft 102 main shaft gear 103 slave gear 104 housing 105 gear shaft 106 magnet 107 storage container 107 a upper end surface 108 magnet 108 a upper end surface 109, 111 magnetic detection element 110 circuit board 112 absolute magnetic encoder 113 Sliding plate 201 Motor main body 202 Gear shaft 203a First dependent gear 203b Second dependent gear 204,208 Storage container 204a, 208a Upper surface 205 Magnet 205a, 209a Upper surface 206 Second gear shaft 207 Third dependent gear 209 Magnet 210 Slide Moving plate

Claims (3)

The rotation angle of the main shaft gear and the subordinate gear of a gear mechanism including a main shaft gear coupled to a main rotation shaft that inputs the output rotation of the motor and at least one sub gear that rotates in accordance with the rotation of the main shaft gear. In a multi-rotation angle detection device that determines the rotation angle of the main rotation shaft,
A housing formed of resin and housing the gear mechanism;
A slave gear positioned between the housing and the circuit board, wherein the slave gear is in direct contact with the circuit board and the housing in a rotatable manner, and is formed of a different resin from the housing. And a gear,
The slave gear is inserted into a bearing steel gear shaft fixed directly in contact with the housing and rotates about the gear shaft, and the gear shaft is generated in the slave gear by rotation of the slave gear. multiple rotation rotation angle detecting apparatus of the frictional heat, characterized in Rukoto is conducted to the housing.   The multi-rotational rotation angle detection device according to claim 1, wherein the housing is formed of a resin based on polyphenyl sulfide, and the dependent gear is formed of a resin based on polyacetal. apparatus. The said dependent gear incorporates a magnet used for detecting a rotation angle of the dependent gear, and an end face of the dependent gear on the circuit board side projects by a predetermined amount from the magnet. 3. The multi-rotation angle detection device according to 1 or 2 .

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