JP6490331B2 - Magnetic gear mechanism and encoder device - Google Patents

Description

The present invention relates to a magnetic type gear mechanism for transmitting the driving force in a non-contact manner by a magnetic force using a magnetic tooth wheel with a permanent magnet, and to an encoder device provided with the magnetic gear mechanism.

  Conventionally, in this type of magnetic gear mechanism, a cylindrical first magnetic gear (worm wheel) is divided into four in the circumferential direction and magnetized alternately in N and S poles (for example, patents) Reference 1). In this magnetic gear mechanism, a cylindrical second magnetic gear (worm) arranged close to and orthogonal to the first magnetic gear is helically magnetized so that the N pole and the S pole are adjacent to each other. The pitch in the circumferential direction of the N pole and S pole of the first magnetic gear is made to coincide with the pitch in the axial direction of the N pole and S pole of the second magnetic gear.

Japanese Patent No. 2683316

  By the way, in the thing of the said patent document 1, although a part of magnetic force line which comes out from the N pole of a 1st magnetic gear goes to the S pole of a 2nd magnetic gear, the remaining part of a magnetic force line is a circumference in a 1st magnetic gear. It will head to the south pole adjacent in the direction. Similarly, a relatively large part of the lines of magnetic force emitted from the N pole of the second magnetic gear are directed to the adjacent S pole in the second magnetic gear. Therefore, in the thing of patent document 1, the magnetic flux which generate | occur | produces from a magnet cannot be utilized effectively, and the drive force which can be transmitted cannot be improved.

  The actual situation is not limited to a worm gear including a worm and a worm wheel, but also in, for example, a magnetic gear mechanism in which the two first magnetic gears are arranged close to each other in parallel.

The main object of the present invention can be effectively utilized magnetic flux generated from the magnet, it is to provide turn magnetic type gear mechanism that can of improving the transmissible driving force, and an encoder device.

  The present invention employs the following means in order to solve the above problems.

  The first means is a magnetic gear, and has a permanent magnet in which an N pole and an S pole are arranged along a predetermined axial direction, and a columnar or cylindrical shape having an outer diameter larger than that of the permanent magnet by a ferromagnetic material. And a pair of gear portions having a plurality of teeth formed on the outer periphery thereof, and the pair of gear portions are arranged on both sides of the predetermined axial direction in a state in which the pair of gear portions are aligned with each other. It is characterized by being sandwiched between.

  According to the above configuration, in the permanent magnet, the N pole and the S pole are arranged along the predetermined axial direction. The pair of gear portions are formed of a ferromagnetic material in a columnar shape or a cylindrical shape having an outer diameter larger than that of the permanent magnet, and the permanent magnets are sandwiched from both sides in the predetermined axial direction in a state in which the axes are aligned. It is out. For this reason, most of the magnetic lines of force enter one gear part from the N pole and enter the S pole from the other gear part. Here, since a plurality of teeth are formed on the outer peripheral portion of each gear portion, the teeth of one gear portion are magnetized to the N pole, and the teeth of the other gear portion are magnetized to the S pole. Therefore, the gear portion can be magnetized by effectively using the magnetic flux generated from the permanent magnet.

  Then, when a predetermined gear having the same pitch formed by a ferromagnetic material is arranged in a non-contact state in proximity to the magnetic gear having the above-described configuration, when the tooth ridges approach each other, and between the tooth ridges The magnetic resistance is different from when the tooth is separated, and the magnetic energy is minimized when the tooth crests approach each other. At this time, if the tooth crests are separated from each other, a force that works to minimize the magnetic energy, that is, a reluctance torque is applied. Therefore, a driving force can be transmitted between the gears. For this reason, a magnetic gear mechanism that transmits a driving force in a non-contact manner by a magnetic force can be easily configured simply by preparing a general gear for the magnetic gear. Furthermore, in this magnetic gear mechanism, a closed circuit of magnetic lines of force can be formed by these gears. That is, the magnetic field lines coming out of the teeth of the gear part magnetized to the N pole (N pole gear part) pass through a predetermined gear formed of a ferromagnetic material, and the gear part magnetized to the S pole (S pole gear part). I will return to my teeth. Therefore, the magnetic flux generated from the permanent magnet can be concentrated on the teeth, and the transmittable driving force can be improved.

  In the second means, the permanent magnet is formed in a columnar shape or a cylindrical shape.

  According to the above configuration, since the permanent magnet is formed in a columnar shape or a cylindrical shape, a permanent magnet having a general shape can be used, and manufacturing of the magnetic gear can be facilitated. The “columnar shape (cylindrical shape)” may be substantially disc-shaped as long as it extends in the axial direction. Similarly, the “columnar (tubular)” may be substantially plate-shaped regardless of its length as long as it extends in the axial direction.

  Specifically, as in the third means, the pair of gear portions are formed in a columnar shape or a cylindrical shape, and the axis of the pair of gear portions and the axis of the permanent magnet coincide with each other. A configuration can be employed.

  In the fourth means, the outer diameter of the portion of the pair of gear portions excluding the teeth is equal to the outer diameter of the permanent magnet.

  According to the above configuration, most of the lines of magnetic force coming out of the N pole are put into one gear part while suppressing the outer diameter of the pair of gear parts from expanding, and most of the lines of magnetic force are put into the S pole from the other gear part. You can enter. Therefore, it is possible to improve the transmittable driving force while suppressing the expansion of the magnetic gear.

  The fifth means is a magnetic gear mechanism, and is formed in a columnar shape or a cylindrical shape by any one of the magnetic gears of the first to fourth means and a ferromagnetic material, and has helical teeth on the outer peripheral portion. And the helical gear pitch of the worm is set corresponding to the pitch of the teeth of the gear portion, and the magnetic gear and the worm are mutually connected. It is characterized by being arranged close to each other in a non-contact state by crossing the axial directions of the two.

  According to the above configuration, the worm is formed in a columnar shape or a cylindrical shape by the ferromagnetic material, and spiral teeth are formed on the outer peripheral portion thereof. The pitch of the spiral teeth of the worm is set corresponding to the pitch of the teeth of the gear portion. The magnetic gear and the worm are arranged close to each other in a non-contact state with their axis directions crossing each other. For this reason, a magnetic worm gear can be constituted by the magnetic gear and the worm described above.

  Further, even in this magnetic worm gear, a closed circuit of magnetic lines of force can be formed by the magnetic gear and the worm. That is, the magnetic lines of force that emerge from the teeth of the N pole gear portion pass through the worm formed of the ferromagnetic material and return to the teeth of the S pole gear portion. Therefore, the magnetic flux generated from the permanent magnet can be concentrated on the teeth, and the transmittable driving force can be improved.

  The sixth means is a magnetic gear mechanism, and is formed in a columnar shape or a cylindrical shape by one of the magnetic gears of the first to fourth means and a ferromagnetic material, and has a plurality of teeth on the outer peripheral portion. A ferromagnetic gear formed, and the pitch of the teeth of the ferromagnetic gear is set corresponding to the pitch of the teeth of the gear portion, and the magnetic gear and the ferromagnetic gear Are arranged close to each other in a non-contact state with their axis directions parallel to each other.

  According to the above configuration, the ferromagnetic gear is formed of a ferromagnetic material in a columnar shape or a cylindrical shape, and a plurality of teeth are formed on the outer peripheral portion thereof. The pitch of the teeth of the ferromagnetic gear is set corresponding to the pitch of the teeth of the gear portion. The magnetic gear and the ferromagnetic gear are arranged close to each other in a non-contact state with their axis directions parallel to each other. For this reason, a magnetic gear mechanism can be comprised with the magnetic gear mentioned above and the said ferromagnetic material gear.

  Further, even in this magnetic gear mechanism, a closed circuit of magnetic lines of force can be formed by the magnetic gear and the ferromagnetic gear. That is, the magnetic lines of force that emerge from the teeth of the N pole gear portion pass through the ferromagnetic gear formed by the ferromagnetic material and return to the teeth of the S pole gear portion. Therefore, the magnetic flux generated from the permanent magnet can be concentrated on the teeth, and the transmittable driving force can be improved.

  The seventh means is an encoder device, wherein the magnetic gear mechanism of the fifth means, a first detector for detecting a rotation angle within one rotation of the worm, and within one rotation of the magnetic gear. A second detection unit that detects a rotation angle, and a calculation unit that calculates a rotation angle exceeding one rotation of the worm based on a detection value by the first detection unit and a detection value by the second detection unit. It is characterized by.

  According to the above configuration, the rotation angle within one rotation of the worm is detected by the first detection unit, and the rotation angle within one rotation of the magnetic gear is detected by the second detection unit. Then, a rotation angle exceeding one rotation of the worm is calculated by the calculation unit based on the detection value by the first detection unit and the detection value by the second detection unit. For this reason, a multi-rotation encoder apparatus that does not require a backup battery can be configured using a magnetic gear mechanism. Here, since the magnetic gear mechanism of the fifth means can improve the drive force that can be transmitted, a small and non-contact encoder device can be realized.

The perspective view which shows the outline | summary of an encoder apparatus. The figure of the worm gear seen from the axial direction of the worm in the first embodiment. The expansion perspective view which expands and shows the tooth periphery of the worm gear of FIG. The figure which shows the magnetic force line which passes along the worm gear of FIG. The figure which shows the example of a change of a worm wheel. The figure which shows the other example of a change of a worm wheel. The figure which shows the other example of a change of a worm wheel. The figure which shows the other example of a change of a worm wheel. The figure which shows the gearwheel of the magnetic gear mechanism which concerns on 2nd Embodiment. The figure which shows the example of a change of the gear of a magnetic gear mechanism.

(First embodiment)
Hereinafter, a first embodiment will be described with reference to the drawings. This embodiment is embodied in an encoder device that holds the rotation angle of a multi-rotating shaft as a rotation state of a non-contact type gear mechanism.

  FIG. 1 is a perspective view showing an outline of the encoder device 10. The encoder device 10 includes a magnetic gear mechanism 20, a first rotation angle sensor 29, a second rotation angle sensor 49, and a control unit 11.

  The magnetic gear mechanism 20 includes a first shaft 21, a first rotating body 22, a worm 23, a second shaft 31, a second rotating body 32, and a worm wheel 33. The worm 23 and the worm wheel 33 constitute a worm gear. The first shaft 21 and the second shaft 31 are orthogonal to (intersected) at a predetermined interval. That is, the projection line of the axis of the second shaft 31 onto the surface including the axis of the first shaft 21 is orthogonal to the first shaft 21.

  A first rotating body 22 and a worm 23 are attached to the first shaft 21. The first rotating body 22 and the worm 23 rotate integrally with the first shaft 21. The first shaft 21 is connected to a drive shaft of a motor, for example, at a robot joint. The first rotation angle sensor 29 is an optical or magnetic rotation angle sensor. The first rotation angle sensor 29 (first detection unit) detects a rotation angle of the first rotating body 22 (worm 23) within one rotation, that is, a rotation angle of the first shaft 21 within one rotation.

  A second rotating body 32 and a worm wheel 33 are attached to the second shaft 31. The second rotating body 32 and the worm wheel 33 rotate integrally with the second shaft 31. The rotation of the worm 23 causes the worm wheel 33 and thus the second shaft 31 (second rotating body 32) to rotate. The second rotation angle sensor 49 is an optical or magnetic rotation angle sensor. The 2nd rotation angle sensor 49 (2nd detection part) detects the rotation angle within 1 rotation of the 2nd rotary body 32 (worm wheel 33).

  Here, in the worm gear, the rotation transmitted from the worm 23 to the worm wheel 33 is decelerated in accordance with the ratio between the number of teeth of the worm 23 and the number of teeth of the worm wheel 33. For example, when the worm 23 rotates 30 times, the worm wheel 33 rotates once. For this reason, a rotation angle within 30 rotations of the worm 23 (a rotation angle exceeding one rotation) is converted into a rotation angle within one rotation of the worm wheel 33.

  The control unit 11 includes a power supply circuit 12, a calculation unit 13, and an output unit 14. The power supply circuit 12 receives power supply from the outside and supplies power to the calculation unit 13 and the output unit 14. The calculation unit 13 is composed of an IC or the like and executes various calculations. The detection values of the rotation angle sensors 29 and 49 are input to the calculation unit 13. The calculation unit 13 calculates a rotation angle exceeding one rotation of the worm 23 (first shaft 21) based on these detection values. The output unit 14 is configured by an IC or the like and executes various calculations. The rotation angle calculated by the calculation unit 13 is input to the output unit 14. The output unit 14 outputs the input rotation angle to the outside (for example, a robot control device).

  Next, the worm gear will be described in detail. FIG. 2 is a view of the worm gear viewed from the axial direction of the worm 23. FIG. 3 is an enlarged perspective view showing the periphery of the teeth of the worm gear in FIG. 2 in an enlarged manner.

  The worm 23 is formed in a cylindrical shape (tubular shape) from a ferromagnetic material such as iron. In the center of the worm 23, a hole 23b having a diameter substantially equal to the outer diameter of the first shaft 21 is formed. Then, the first shaft 21 is inserted into the hole 23b, and the worm 23 and the first shaft 21 are fixed. Helical teeth 23 a are formed on the outer periphery of the worm 23. The teeth 23 a are formed at a predetermined pitch in the axial direction of the worm 23.

  The worm wheel 33 (magnetic gear) includes a magnet 34 and a pair of gear portions 35. The magnet 34 (permanent magnet) is formed in a cylindrical shape (tubular shape) by a permanent magnet such as a ferrite magnet or a rare earth metal magnet. The “cylindrical shape” is not limited in length as long as it extends in the axial direction, and may be substantially disk-shaped. In the magnet 34, the N pole and the S pole are arranged along the axial direction (predetermined axis direction) of the magnet 34.

  The gear portion 35 is formed in a cylindrical shape (tubular shape) having an outer diameter larger than the outer diameter of the magnet 34 by a ferromagnetic material such as iron. The pair of gear portions 35 sandwich the magnet 34 from both sides in the axial direction of the magnet 34 in a state where the axes of the gear portions 35 coincide with each other. The axis of the pair of gear portions 35 and the axis of the magnet 34 coincide with each other. A hole having a diameter substantially equal to the outer diameter of the second shaft 31 is formed in the center of the pair of gear portions 35 and the magnet 34. Then, the second shaft 31 is inserted into these holes, and the worm wheel 33 and the second shaft 31 are fixed.

  A plurality of teeth 35 a arranged in the circumferential direction are formed on the outer peripheral portion of the pair of gear portions 35. The outer diameter of the portion of the pair of gear portions 35 excluding the teeth 35 a (the diameter of a circle passing through the root of the teeth 35 a) is set to be approximately equal to the outer diameter of the magnet 34. The pitch in the circumferential direction of the teeth 35a of the gear portion 35 matches the pitch in the axial direction of the teeth 23a of the worm 23. That is, the pitch of the helical teeth 23 a of the worm 23 is set corresponding to the pitch of the teeth 35 a of the gear portion 35.

  The worm wheel 33 and the worm 23 are arranged close to each other in a non-contact state with their axis directions orthogonal (intersect). That is, the projection line of the axis of the worm wheel 33 onto the surface including the axis of the worm 23 is orthogonal to the axis of the worm 23. One tooth 35a of each of the pair of gear portions 35 and one line of teeth 23a of the worm 23 are closest to each other and form a predetermined clearance.

  As the worm 23 rotates, the pair of teeth 35a and one line of the teeth 23a are interlocked in a state of being attracted by a magnetic force. For example, when one line of the teeth 23 a moves upward (in the axial direction of the worm 23) along with the rotation of the worm 23, the pair of teeth 35 a is pulled in the clockwise direction (the circumferential direction of the gear portion 35). . When the worm 23 further rotates, the pair of adjacent teeth 35a in the counterclockwise direction and the adjacent strip in the downward direction of the teeth 23a are in the closest state. Then, the pair of teeth 35a and one row of teeth 23a are interlocked in a state of being attracted by a magnetic force.

  Next, the lines of magnetic force passing through the worm gear will be described with reference to FIG. As indicated by the arrows in the figure, the magnetic field lines coming out of the N pole of the magnet 34 enter a gear portion 35 formed of a ferromagnetic material and attached to the N pole. Here, the outer diameter of the gear portion 35 excluding the teeth 35 a is equal to the outer diameter of the magnet 34. For this reason, a magnetic force line enters the portion of the gear portion 35 excluding the teeth 35a.

  The magnetic lines of force that have entered the gear portion 35 pass through the inside of the gear portion 35 and enter the worm 23 that is formed of a ferromagnetic material and is disposed close to the worm wheel 33. Specifically, the lines of magnetic force are guided to the tooth 35a closest to the tooth 23a of the worm 23, and enter the tooth 23a of the worm 23 from the tooth 35a. The magnetic field lines pass through the worm 23 and enter the gear portion 35 attached to the south pole of the magnet 34. Specifically, the lines of magnetic force are guided to one line of the teeth 23a and enter the closest tooth 35a from the one line of the teeth 23a.

  The lines of magnetic force that enter the gear portion 35 enter the south pole of the magnet 34 through the inside of the gear portion 35. Here, the outer diameter of the gear portion 35 excluding the teeth 35 a is equal to the outer diameter of the magnet 34. For this reason, a magnetic force line enters the south pole from a portion of the gear portion 35 excluding the teeth 35a. Therefore, in this worm gear, a closed circuit of magnetic lines of force is formed by the worm wheel 33 and the worm 23.

  In this way, the gear portion 35 attached to the N pole, and thus the plurality of teeth 35a formed on the gear portion 35, are magnetized to the N pole. In addition, the gear portion 35 attached to the S pole, and thus the plurality of teeth 35a formed on the gear portion 35, are magnetized to the S pole. Then, the tooth 35a closest to one line of the teeth 23a of the worm 23 and the one line of the teeth 23a of the worm 23 are attracted by a magnetic force. Therefore, the worm wheel 33 rotates as the worm 23 rotates.

  The embodiment described in detail above has the following advantages.

  The magnet 34 has an N pole and an S pole arranged along a predetermined axial direction (the axial direction of the cylindrical magnet 34). The pair of gear portions 35 are formed of a ferromagnetic material in a cylindrical shape having an outer diameter larger than that of the magnet 34, and the magnet 34 is sandwiched from both sides in the predetermined axial direction in a state where the axes of the pair are aligned. It is out. For this reason, most of the magnetic field lines enter one gear portion 35 from the N pole and enter the S pole from the other gear portion 35. Here, since a plurality of teeth 35a are formed on the outer peripheral portion of each gear portion 35, the teeth 35a of one gear portion 35 are magnetized to the N pole, and the teeth 35a of the other gear portion 35 are set to the S pole. Magnetized. Therefore, the gear portion 35 can be magnetized by effectively using the magnetic flux generated from the magnet 34.

  Since the worm 23 formed of a ferromagnetic material and having the same pitch is disposed close to the worm wheel 33 in a non-contact state, a driving force can be transmitted between them. For this reason, a worm gear that transmits a driving force in a non-contact manner by a magnetic force can be easily configured simply by preparing a general worm 23 for the worm wheel 33. Further, in this worm gear, a closed circuit of magnetic lines of force can be formed by the worm wheel 33 and the worm 23. That is, the lines of magnetic force emitted from the teeth 35a of the gear portion 35 magnetized to the N pole pass through the worm 23 formed of a ferromagnetic material and return to the teeth 35a of the gear portion 35 magnetized to the S pole. Therefore, the magnetic flux generated from the magnet 34 can be concentrated on the teeth 35a, and the transmittable driving force can be improved.

  -Since the magnet 34 is formed in the cylindrical shape, the magnet 34 of a general shape can be utilized. Further, it is not necessary to magnetize the plurality of teeth 35a of the gear portion 35 individually. Therefore, manufacture of the worm wheel 33 can be facilitated.

  The outer diameter of the portion of the pair of gear portions 35 excluding the teeth 35 a is equal to the outer diameter of the magnet 34. For this reason, while suppressing an increase in the outer diameter of the pair of gear portions 35, most of the magnetic field lines coming out of the N pole are put into one gear portion 35, and most of the magnetic field lines are transferred from the other gear portion 35 to the S pole. You can enter. Accordingly, it is possible to improve the transmittable driving force while suppressing the expansion of the worm wheel 33.

  The worm 23 is formed in a cylindrical shape by a ferromagnetic material, and spiral teeth 23a are formed on the outer peripheral portion thereof. The pitch of the helical teeth 23 a of the worm 23 is set corresponding to the pitch of the teeth 35 a of the gear portion 35. The worm wheel 33 and the worm 23 are arranged close to each other in a non-contact state with their axial directions orthogonal to each other. Therefore, the worm wheel 33 and the worm 23 can constitute a magnetic worm gear.

  The rotation angle within one rotation of the worm 23 is detected by the first rotation angle sensor 29, and the rotation angle within one rotation of the worm wheel 33 is detected by the second rotation angle sensor 49. Then, the calculation unit 13 calculates a rotation angle exceeding one rotation of the worm 23 based on the detection value by the first rotation angle sensor 29 and the detection value by the second rotation angle sensor 49. For this reason, a multi-rotation encoder apparatus that does not require a backup battery can be configured using the worm gear. Here, since the worm gear can improve the drive force that can be transmitted, a small, non-contact encoder device 10 can be realized.

  In addition, the said embodiment can also be changed and implemented as follows. About the same member as the said embodiment, description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 5, it is possible to employ a worm wheel 133 including a magnet 134 that is formed to have a longer axial length than the gear portion 35. That is, the axial lengths of the gear portion 35 and the magnets 34 and 134 can be set as appropriate according to the application.

  -As shown in FIG. 6, the outer diameter of the magnet 234 can also be set smaller than the outer diameter of the part except the tooth | gear 35a in the gear part 35. FIG. Even in such a worm wheel 233, while suppressing an increase in the outer diameter of the pair of gear parts 35, most of the magnetic field lines coming out of the N pole are put into one gear part 35, and most of the magnetic field lines are put into the other of the other magnetic field lines. The gear 35 can be inserted into the south pole. Also, the axis of the pair of gear portions 35 and the axis of the magnet 234 can be shifted.

  -The outer diameter of a pair of gear part 35 and the outer diameter of the magnet 34 can also be made substantially equal.

  -As shown in FIG. 7, the worm wheel 333 provided with the hexagonal cylindrical magnet 334 is also employable. Even with such a worm wheel 333, the same operational effects as the worm wheel 33 can be achieved. Moreover, the worm wheel provided with another polygonal cylindrical magnet can also be employ | adopted. Further, the pair of gear portions 35 can also be formed in a polygonal cylindrical shape except for the outer peripheral portion where the teeth 35a are formed.

  In the above embodiment, the cylindrical magnet 34 and the cylindrical gear portion 35 are adopted. However, by attaching the worm wheel 33 to the tip of the second shaft 31, the magnet 34 and the gear portion 35 are columnar (columnar). It can also be formed. Similarly, the worm 23 can be formed in a columnar shape (columnar shape) by attaching the worm 23 to the tip of the first shaft 21.

  As shown in FIG. 8, a worm wheel 433 including two (plural) magnets 34 may be employed. Further, a connecting portion 36 formed in a cylindrical shape by a ferromagnetic material may be provided between the two magnets 34. According to such a configuration, the length of the worm wheel 433 in the axial direction can be extended while using a general thin magnet 34.

  The teeth 35a of the pair of gear portions 35 may coincide with each other in the circumferential direction of the gear portion 35 or may be slightly shifted. That is, the worm wheel 33 may constitute a spur gear or a helical gear. However, it is desirable that the positions of the teeth 35a in the pair of gear portions 35 are set in correspondence with the spiral shape of the teeth 23a of the worm 23.

(Second Embodiment)
The second embodiment will be described below with reference to the drawings. In the present embodiment, as shown in FIG. 9, a magnetic gear mechanism 120 is constituted by two spur gears.

  The magnetic gear mechanism 120 includes a magnetic gear 43 and a ferromagnetic gear 53. The magnetic gear 43 has the same configuration as the worm wheel 33 described above.

  The ferromagnetic gear 53 is made of a ferromagnetic material such as iron and has substantially the same dimensions as the magnetic gear 43. The ferromagnetic gear 53 is formed of a ferromagnetic material in a cylindrical shape, and a plurality of teeth 53a are formed on the outer peripheral portion. The outer diameter of the ferromagnetic gear 53 is the same as the outer diameter of the magnetic gear 43, and the pitch of the teeth 53 a of the ferromagnetic gear 53 is the same as the pitch of the teeth 35 a of the magnetic gear 43.

  The magnetic gear 43 and the ferromagnetic gear 53 are arranged close to each other in a non-contact state with their axis directions parallel to each other. One tooth 35a of each of the pair of gear portions 35 and one tooth 53a of the ferromagnetic gear 53 are closest to each other and form a predetermined clearance.

  As indicated by the arrows in the drawing, the magnetic lines of force that enter the gear portion 35 pass through the inside of the gear portion 35 and are formed of a ferromagnetic material, and are arranged close to the magnetic gear 43 and are arranged in a ferromagnetic gear 53. Enter. Specifically, the lines of magnetic force are guided to the tooth 35 a closest to one tooth 53 a of the ferromagnetic gear 53, and enter the one tooth 53 a of the ferromagnetic gear 53 from this tooth 35 a. The magnetic lines of force pass through the inside of the ferromagnetic gear 53 and enter the gear portion 35 attached to the south pole of the magnet 34. Specifically, the lines of magnetic force are guided to the one tooth 53a and enter the tooth 35a closest to the tooth 53a. Therefore, in the magnetic gear mechanism 120, the magnetic gear 43 and the ferromagnetic gear 53 form a closed circuit of magnetic lines of force.

  Along with the rotation of the ferromagnetic gear 53, the teeth 35a of the pair of gear portions 35 and one tooth 53a of the ferromagnetic gear 53 are interlocked in a state of being attracted by a magnetic force. For example, when one tooth 53a moves in the counterclockwise direction with the rotation of the ferromagnetic gear 53, the pair of teeth 35a rotate in the clockwise direction by being attracted thereto. When the ferromagnetic gear 53 further rotates, the adjacent tooth 53a in the clockwise direction and the pair of adjacent teeth 35a in the counterclockwise direction become closest to each other. Then, the pair of teeth 35a and the teeth 53a are interlocked with each other while being attracted by a magnetic force.

  The embodiment described in detail above has the following advantages. Here, only the advantages different from the first embodiment will be described.

  The ferromagnetic gear 53 is formed of a ferromagnetic material in a cylindrical shape, and a plurality of teeth 53a are formed on the outer peripheral portion thereof. The pitch of the teeth 53 a of the ferromagnetic gear 53 is set corresponding to the pitch of the teeth 35 a of the gear portion 35. The magnetic gear 43 and the ferromagnetic gear 53 are arranged close to each other in a non-contact state with their axis directions parallel to each other. Therefore, the magnetic gear mechanism 120 can be configured by the magnetic gear 43 and the ferromagnetic gear 53.

  In the magnetic gear mechanism 120, the magnetic gear 43 and the ferromagnetic gear 53 can form a closed circuit of magnetic lines of force. That is, the lines of magnetic force emitted from the teeth 35a of the gear portion 35 attached to the N pole return to the teeth 35a of the gear portion 35 attached to the S pole through the ferromagnetic gear 53 formed of a ferromagnetic material. It becomes. Therefore, the magnetic flux generated from the magnet 34 can be concentrated on the teeth 35a, and the transmittable driving force can be improved.

  In addition, the said embodiment can also be changed and implemented as follows. About the same member as the said embodiment, description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  The magnetic gear 43 may be a driving gear, and the ferromagnetic gear 53 may be a driven gear.

  The teeth 35a of the pair of gear portions 35 may be slightly displaced from each other in the circumferential direction of the gear portion 35. That is, the magnetic gear 43 may constitute a helical gear. In this case, the ferromagnetic gear 53 may be a helical gear corresponding to the magnetic gear 43.

  As shown in FIG. 10, the magnetic gear mechanism 220 can be configured by two magnetic gears 43. In this case, the magnets 34 of the two magnetic gears 43 are arranged so that their magnetic poles are in opposite directions. Even with such a configuration, the magnetic gear mechanism 220 can form a closed circuit of magnetic lines of force. Further, since the two magnetic gears 43 are each provided with the magnet 34, the magnetic flux can be increased and the driving force that can be transmitted can be improved.

  DESCRIPTION OF SYMBOLS 10 ... Encoder apparatus, 13 ... Calculation part, 20 ... Magnetic gear mechanism, 23 ... Worm, 23a ... Teeth, 29 ... 1st rotation angle sensor (1st detection part), 33 ... Worm wheel (magnetic gear), 34 ... Magnet (permanent magnet), 35 ... gear part, 35a ... tooth, 43 ... magnetic gear, 49 ... second rotation angle sensor (second detection part), 53 ... ferromagnetic gear, 53a ... tooth, 120 ... magnetism Type gear mechanism, 133 ... worm wheel (magnetic gear), 134 ... magnet (permanent magnet), 220 ... magnetic gear mechanism, 233 ... worm wheel (magnetic gear), 234 ... magnet (permanent magnet), 333 ... worm Wheel (magnetic gear), 334 ... magnet (permanent magnet), 433 ... worm wheel (magnetic gear).

Claims (5)

A permanent magnet in which a north pole and a south pole are arranged along a predetermined axial direction;
A magnetic gear provided with a pair of gear portions formed by a ferromagnetic body in a columnar shape or a cylindrical shape having an outer diameter equal to or larger than that of the permanent magnet, and a plurality of teeth formed on the outer peripheral portion ;
A worm that is formed in a columnar shape or a cylindrical shape by a ferromagnetic material, and in which a spiral tooth is formed on the outer periphery,
A magnetic gear mechanism comprising:
The axis of the pair of gear portions and the axis of the permanent magnet are coincident,
The pair of gear portions sandwich the permanent magnet from both sides in the predetermined axial direction in a state where the axes of the pair are aligned with each other .
Corresponding to the pitch of the teeth of the front Symbol gear unit, the pitch of the helical teeth of the worm is set,
The teeth of the pair of gear portions are aligned with each other in the circumferential direction of the gear portion, or are slightly shifted,
The projection line of the axis of the magnetic gear on the surface including the axis of the worm intersects the axis of the worm,
The magnetic gear and the worm are arranged close to each other in a non- contact state, and the shortest distance between the teeth of the pair of gear portions and the teeth of the worm is shorter than the distance between the pair of gear portions. A magnetic gear mechanism.   The magnetic gear mechanism according to claim 1, wherein the permanent magnet is formed in a columnar shape or a cylindrical shape. It said pair of magnetic gear mechanism of the gear unit according to claim 2 Ru Tei is formed in a columnar or cylindrical.   The magnetic gear mechanism according to claim 3, wherein an outer diameter of a portion excluding the teeth in the pair of gear portions is equal to an outer diameter of the permanent magnet. The magnetic gear mechanism according to any one of claims 1 to 4,
A first detector for detecting a rotation angle within one rotation of the worm;
A second detector for detecting a rotation angle within one rotation of the magnetic gear;
A calculation unit capable of calculating a rotation angle exceeding one rotation of the worm based on the detection value by the first detection unit and the detection value by the second detection unit;
An encoder device comprising:

Images