JP2009204391A - Stepping motor for measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor for a measuring instrument which eliminates a necessity for positioning an intermediate gear, and is excellent in the assembly workability. <P>SOLUTION: The stepping motor for the measuring instrument includes: a first support shaft 10, a rotor magnet 2, a rotor gear 3, the intermediate gear 4 having first and second gears 4a, 4b; a third support shaft 6; an output gear 5; a case 12; an excitation coil 9; and a fixed magnet (a magnetic member) 7. In the stepping motor, the gears 3-5 are coupled by a rotational bias force from the fixed magnet 7 in a non-excitation state so as to cause a movable abutting section 15a to press a fixed abutting section 15b. The intermediate gear 4 is assembled after the rotor gear 3 and the output gear 5 so as to engage the second gear 4b prior to the first gear 4a. The number of teeth of the first gear 4a is set to a natural number multiple of the number of teeth of the second gear 4b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an instrument stepping motor that is incorporated in, for example, a pointer-type instrument mounted on a vehicle and drives the pointer.

  As this type of instrument stepping motor, for example, the one described in Patent Document 1 below is known. This instrument stepping motor includes a first support shaft (rotor shaft member), a rotor magnet (rotor) that is pivotally supported on the first support shaft and is multipolarly magnetized along the rotation direction on the outer circumferential surface. The rotor gear (rotor gear) that is supported by the first support shaft so as to rotate coaxially with the rotor magnet, the second support shaft (positioning member), and the second support shaft that is supported by the second support shaft. An intermediate gear having a first gear portion meshing with the rotor gear and a second gear portion pivotally supported by the second support shaft so as to rotate coaxially with the first gear portion; and a third support shaft ( A guide shaft), an output gear (pointer gear) that is supported by the third support shaft and meshes with the second gear portion, an excitation coil that rotates the rotor magnet in response to an excitation signal input, and the excitation coil. Yoke (stator) that guides the rotating magnetic field to the rotor magnet A case (case member) that houses the exciting coil, rotor magnet, rotor gear, intermediate gear, output gear, and yoke and supports the first, second, and third rotating shafts. A movable contact portion (protrusion) is provided, and the case is provided with a fixed contact portion (stopper) that stops the rotation of the third support shaft by contacting the movable contact portion.

  The instrumental stepping motor described in Patent Document 1 configured as described above can hold the rotor magnet by the detent torque that acts between the yoke and the rotor magnet, so that no excitation signal is input to the excitation coil. Even in the non-excited state (for example, when the power is turned off when the vehicle is mounted), the pointer can be kept at a predetermined position.

  On the other hand, for example, an instrument stepping motor described in Patent Document 2 below is also known. This instrument stepping motor has an intermediate gear and a rotor gear and an output gear directly meshed with each other, and has no yoke and directly drives a rotor magnet to an exciting coil. It is different from the motor. This type of instrument stepping motor includes a magnetic member (fixed magnet) that urges the rotor magnet in a predetermined rotational direction when there is no excitation signal input and is in an unexcited state. It is necessary to connect the rotor gear and the output gear so that the movable contact portion of the output gear presses the fixed contact portion of the case by the rotational biasing force.

Then, it is considered to adopt a three-axis configuration (two-stage reduction configuration) by adding an intermediate gear described in the following Patent Literature 1 to a yokeless and two-axis configuration (single-speed reduction configuration) instrument stepping motor described in Patent Literature 2 below. It is done. In this case, it is necessary to connect the three gears (the rotor gear, the intermediate gear, and the output gear) so that the movable contact portion of the output gear presses the fixed contact portion of the case by the rotational biasing force of the magnetic member. To connect in this way, after determining the rotational position of the rotor magnet (rotor gear) relative to the magnetic member and the rotational position of the movable contact portion (output gear) relative to the fixed contact portion, the intermediate gear is moved to the rotor. What is necessary is just to insert between a gearwheel and an output gearwheel, and to connect both gearwheels.
JP 2001-327149 A JP 2001-041981 A

  However, in the configuration in which only Patent Documents 1 and 2 are combined, in the intermediate gear, of the first gear portion and the second gear portion, which gear portion meshes with the counterpart gear first, Since the correlation between the number of teeth of the first gear portion and the number of teeth of the second gear portion is not particularly taken into consideration, the rotational position of the intermediate gear (rotor gear and It is necessary to pinpoint which gear of the intermediate gear meshes with each of the output gears, which makes assembly workability difficult. If positioning of the intermediate gear is not performed, the teeth collide with each other at the time of assembly, and the assembly cannot be performed, or the position of the rotor gear or the output gear positioned with great effort is shifted.

  The present invention pays attention to the above-mentioned problems, and provides an instrument stepping motor that does not require positioning of an intermediate gear and has excellent assembling workability.

  In order to solve the above-described problems, the present invention provides a first support shaft, a rotor magnet that is pivotally supported on the first support shaft and is multipolarly magnetized along the rotation direction on the outer peripheral surface, and the rotor magnet. A rotor gear pivotally supported by the first support shaft so as to rotate coaxially therewith, a second support shaft, a first gear portion pivotally supported by the second support shaft and meshed with the rotor gear, and An intermediate gear having a second gear supported by the second support shaft so as to rotate coaxially with the first gear portion, a third support shaft, and the third support shaft. An output gear meshing with the second gear portion, a case housing at least the rotor magnet, rotor gear, intermediate gear, and output gear and supporting the first, second, and third rotating shafts; An excitation coil that rotates the rotor magnet in response to a signal input, and an excitation signal input A magnetic member that urges the rotor magnet in a predetermined rotational direction in a non-excited state, a movable contact portion is provided on the output gear, and the case is in contact with the movable contact portion A fixed abutting portion for stopping the rotation of the third support shaft is provided, and the movable abutting portion causes the fixed abutting portion to be rotated by a rotational biasing force of the magnetic member acting on the rotor magnet in the non-excited state. In an instrument stepping motor in which the rotor gear, the intermediate gear, and the output gear are connected so as to press, the intermediate gear is connected to the second gear before the first gear meshes with the rotor gear. It is configured to be assembled after the rotor gear and the output gear so that the portion meshes with the output gear, and the number of teeth of the first gear portion is set to a natural number times the number of teeth of the second gear portion. Characterized in that by comprising.

  According to the present invention, the rotor magnet is directly driven by the exciting coil.

  According to the present invention, it is possible to provide a display device that can achieve the initial object and can avoid an increase in size even when a plurality of display panels are used in an overlapping manner.

  Hereinafter, an embodiment of the present invention will be described based on an instrument device using a stepping motor. 1 to 5 show an embodiment of the present invention.

  The stepping motor 1 used in the instrument device M of the present embodiment includes a rotor magnet 2 magnetized with multiple poles, a rotor gear 3 fixed to the rotor magnet 2, and a first gear portion 4a meshing with the rotor gear 3. An intermediate gear 4 having a second gear portion 4b provided coaxially with the first gear portion 4a, an output gear 5 meshing with the second gear portion 4b of the intermediate gear 4, and a rotating magnetic field are generated. Two excitation coils 9 for applying a rotational force to the rotor magnet 2, a metal (for example, stainless steel) first support shaft 10 serving as the rotation center of the rotor magnet 2, and a metal serving as the rotation center of the intermediate gear 4. A second support shaft 11 made of stainless steel (for example, made of stainless steel), a third support shaft 6 made of metal (for example, made of stainless steel) that is the rotation center of the output gear 5, and a fixed magnet (magnetic) Member) 7, rotor magnet 2, b And a case 12 that accommodates the first support shaft 10, the second support shaft 11, and the third support shaft 6. It is what you have.

  The rotor magnet 2 is made of a synthetic resin having magnetism called a so-called plastic magnet, has a circular shape, and has a donut shape with a through hole in the center. The rotor gear 3 and the first support shaft 10 pass through this through hole. The rotor magnet 2 includes a large number of magnetic poles so as to be uniform in the radial direction around the rotation axis. In this embodiment, two N poles and two S poles are provided for a total of four magnetic poles. Therefore, when the rotation is performed with the first support shaft 10 as the center axis, the outer peripheral surface of the rotor magnet 2 is magnetized in multiple poles along the rotation direction.

  The rotor gear 3 is made of a synthetic resin, such as POM (polyacetal), and rotates coaxially with the rotation of the rotor magnet 2 as described above. Further, the first support shaft 10 is supported by the first support shaft 10 by passing through the rotor gear 3.

  The intermediate gear 4 is made of a synthetic resin, for example, POM (polyacetal), and integrally includes a first gear portion 4a and a second gear portion 4b. The first gear portion 4 a meshes with the rotor gear 3. The second gear portion 4 b meshes with the output gear 5. The first gear portion 4a and the second gear portion 4b are coaxially supported by the second support shaft 11 serving as the rotation center, and rotate coaxially with each other.

  Similarly to the rotor gear 3 and the intermediate gear 4, the output gear 5 is made of a synthetic resin such as POM (polyacetal) and meshes with the second gear portion 4 b of the intermediate gear 4. The output gear 5 is provided with a third support shaft 6 serving as a rotation center.

  In FIG. 2, a first protrusion (movable contact portion) 15 a is integrally provided on the lower surface of the output gear 5. The first protrusion 15a comes into contact with a second protrusion (fixed contact portion) 15b provided on the case 12, which will be described later, and stops the rotation of the output gear 5 at a predetermined position. The first protrusion (movable contact portion) 15a and the second protrusion (fixed contact portion) 15b constitute the stopper means 15.

  In the present embodiment, the intermediate gear 4 and the output gear 5 transmit the rotation of the rotor magnet 2 at a reduced speed.

  The exciting coil 9 is formed by winding a conductive metal wire such as copper around a bobbin 9a made of synthetic resin. The exciting coil 9 is connected to the control means via a terminal 9b provided on the bobbin 9a, and generates a rotating magnetic field that rotates the rotor magnet 2 in response to an excitation signal input through the control means.

  The bobbin 9a is a cylindrical body having a through hole having a rectangular cross-sectional shape. And the exciting coil 9 is arrange | positioned around the rotor magnet 2, and a part of disk surface of the rotor magnet 2 and the said through-hole are in the state which a part of the rotor magnet 2 entered in the said through-hole of the bobbin 9a. The inner peripheral surfaces of are facing each other.

  The two excitation coils 9 are respectively input with drive waveforms output from control means (not shown), so that a rotating magnetic field is generated in the rotor magnet 2 and a rotational force is applied to the rotor magnet 2. .

  The case 12 is made of a synthetic resin, such as PBT (polybutylene terephthalate), and is divided into upper and lower parts. The case 12 divided vertically is fixed by hooking a locking claw 12a provided on each case 12. The case 12 is integrally provided with a second protrusion 15b that abuts the first protrusion 15a provided on the output gear 5, and the fixed magnet 7 is fixedly held at a predetermined position facing the rotor magnet 2. is doing. The case 12 rotatably supports the first support shaft 10, the second support shaft, and the third support shaft 6.

  The fixed magnet 7 is a cylindrical magnet having N and S2 poles magnetized in the radial direction, and biases the rotor magnet 2 in a predetermined rotational direction when no excitation signal is input. .

  FIG. 4 shows the stepping motor 1 used in the instrument device M. The instrument device M of the present embodiment displays the speed of the vehicle using the pointer 14.

  The pointer 14 is attached to the third support shaft 6. Behind the pointer 14 is provided a display board 17 provided with indicator portions 17a such as scales and characters indicated by the pointer 14. The pointer 14 is stably held at a predetermined position, that is, a position indicating “0” of the vehicle speed in this embodiment, by the stopper means 15 and the fixed magnet 7 provided in the stepping motor 1.

  FIG. 5 is an explanatory view schematically showing a coupling mode of the rotor gear 3, the intermediate gear 4, and the output gear 5 in the non-excited state, and includes a first protrusion 15 a and a second protrusion that constitute the stopper means 15. In this state, the pointer 14 is in contact with a predetermined position. The first projecting portion 15a and the second projecting portion 1b are set so as not to be separated from each other (to be in a pressed state) by the rotational biasing force of the fixed magnet 7 acting on the rotor magnet 2.

  That is, the rotor magnet 2 and the fixed magnet 7 are set, for example, in a positional relationship in which the S pole of the fixed magnet 7 repels the S pole of the rotor magnet 2. For this reason, the rotational force of CCW (counterclockwise direction-see arrow in FIG. 5) acts on the rotor magnet 2, and the intermediate gear 4 meshing with the rotor gear 3 has a CW opposite to the rotor magnet 2 and the rotor gear ( Rotational force in the clockwise direction (see arrow in FIG. 5) is applied, and CCW (counterclockwise direction in FIG. 5 -see arrow in FIG. 5) opposite to the intermediate gear 4 is applied to the output gear 5 meshing with the intermediate gear 4. . For this reason, the pointer 14 stops in a state where the first protrusion 15a is pressed against the second protrusion 15b.

Here, the setting of the number of teeth of the intermediate gear 4 and the assembly order will be described.
First, in the present embodiment, the first gear portion 4a of the intermediate gear 4 is 66 pieces, the second gear portion 4b is 11 pieces, that is, the first gear portion 4a is set to a natural number times the second gear portion 4b. (By the way, the number of teeth of the rotor gear 3 is set to 12 and the output gear 5 is set to 90).

  In assembling the gears 3 to 5, first, the rotor gear 3 and the output gear 5 are set in the case 12 (the temporary holding state is achieved by the lower case 12). At this time, the rotational position of the rotor gear 3 is positioned at a predetermined position based on the positional relationship between the fixed magnet 7 and the rotor magnet 2. The rotational position of the output gear 5 is positioned at a predetermined position based on the positional relationship of the movable contact portion 15a with respect to the fixed contact portion 15b. Positioning of the rotor gear 3 and the output gear 5 is performed using an appropriate method on the production line, and each predetermined position is a state in which all the gears 3 to 5 are set (assembled) in the final state. In particular, it indicates a position where the movable contact portion 15a is pressed against the fixed contact portion 15b by the rotational biasing force of the fixed magnet 7, and is not necessarily limited to the position shown in FIG. Next, the intermediate gear 4 is set so as to be inserted between the rotor gear 3 and the output gear 5 (in this case, a temporary holding state is achieved by the lower case 12, and the main case is assembled by assembling the upper case 12). The intermediate gear 4 is configured such that the second gear portion 4b having a small diameter is engaged with the output gear 5 before the first gear portion 4a having a large diameter is engaged with the rotor gear 3. After the second gear portion 4 b meshes with the output gear 5, the first gear portion 4 a meshes with the rotor gear 3.

  Here, paying attention to the positional relationship between the first gear part 4a and the second gear part 4b, as described above, the first gear part 4a is 66 pieces, and the second gear part 4b is Since 11 are set, eleven meshing points EP1 to EP11 corresponding to individual teeth of the second gear portion 4b are formed in the first gear portion 4a in the radial direction of the intermediate gear 4. In the mesh points EP1 to EP11, the intervals between adjacent mesh points EP1 to EP11 are all constant, and six teeth are located between the mesh points EP1 to EP11. Further, the meshing points EP1 to EP11 are mechanically (performance) equivalent as normal meshing positions with the rotor gear 3, and all the meshing points EP1 to EP11 mesh with the predetermined teeth of the rotor gear 3. Perform the same function.

  Therefore, if the second gear portion 4b is first meshed with the predetermined tooth of the output gear 5, any one of the meshing points EP1 to EP11 always meshes with the predetermined tooth of the rotor gear 3. It is not necessary to determine the rotational position of the intermediate gear 4 with respect to each of the output gear 5 and the output gear 5, and it is possible to improve the assembly workability. The problem that the position of the rotor gear 3 or the output gear 5 is displaced can also be solved.

  Even if the first gear portion 4a is set to be a natural number multiple of the second gear portion 4b, if the first gear portion 4a is meshed before the second gear portion 4b, it is a precious meshing point. EP1 to EP11 are ignored, and the intended merit cannot be obtained.

  Similarly, even if the second gear portion 4a is meshed before the first gear portion 4b, the meshing point is determined unless the first gear portion 4a is set to a natural number times the second gear portion 4b. Is limited, and the intended merit cannot be obtained.

  As described above, according to the present invention, the first support shaft 10, the rotor magnet 2 that is pivotally supported on the first support shaft 10 and is multipolarly magnetized along the rotation direction on the outer peripheral surface, A rotor gear 3 that is supported on the first support shaft 10 so as to rotate coaxially with the rotor magnet 2, a second support shaft 11, and a second gear that is supported on the second support shaft 11 and meshes with the rotor gear 3. An intermediate gear 4 having a first gear portion 4a and a second gear 4b pivotally supported by the second support shaft so as to rotate coaxially with the first gear portion 4a, and a third support shaft 6. The output gear 5 that is supported by the third support shaft 6 and meshes with the second gear portion 4b, and at least the rotor magnet 2, the rotor gear 3, the intermediate gear 4, and the output gear 5 are housed and the first, second, and second gears are accommodated. A case 12 that pivotally supports the third rotary shafts 10, 11, and 6, and a rotor magnet 2 in response to an excitation signal input. An excitation coil 9 to be rotated and a fixed magnet (magnetic member) 7 for urging the rotor magnet 2 in a predetermined rotation direction when no excitation signal is input are provided, and the output gear 5 has a movable contact portion 15a. And a fixed contact portion 15b for stopping the rotation of the third support shaft 6 by contacting the movable contact portion 15a with the case 12, and the fixed magnet 7 acting on the rotor magnet 2 in a non-excited state. In the instrument stepping motor in which the rotor gear 3, the intermediate gear 4, and the output gear 5 are connected so that the movable contact portion 15 a presses the fixed contact portion 15 b by the rotational biasing force of the intermediate gear 4, the intermediate gear 4 is the first one. The first gear portion 4 is configured to be assembled after the rotor gear 3 and the output gear 5 so that the second gear portion 4b meshes with the output gear 5 before the gear portion 4a of the first gear portion 4a meshes with the rotor gear 3. By setting the number of teeth of the second gear portion 4b to be a natural number times the number of teeth of the second gear portion 4b, there is no need to determine the rotational position of the intermediate gear 4 with respect to the rotor gear 3 and the output gear 5, respectively. Workability can be improved, and the problem that the teeth collide with each other at the time of assembling and the assembling becomes impossible or the position of the rotor gear 3 or the output gear 5 positioned with great effort can be solved.

  Further, the present invention is suitable for a stepping motor of the type in which the rotor magnet 3 is directly driven by the exciting coil 9 without using a magnetic member such as a yoke.

  In the present embodiment, when the first gear portion 4a is set to a natural number multiple of the second gear portion 4b, 66 first gear portions 4a of the intermediate gear 4 and 11 Although the number of gears 4a and 4b is set to be a natural number, it can be arbitrarily set.

The top view of the stepping motor of one embodiment of the present invention. Sectional drawing of the AA line in FIG. The top view of the stepping motor which removed the upper case of the embodiment. The front view of the instrument apparatus using the stepping motor of the embodiment. Explanatory drawing of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stepping motor 2 Rotor magnet 3 Rotor gear 4 Intermediate gear 4a 1st gear 4b 2nd gear 5 Output gear 6 Output shaft 7 Fixed magnet (magnetic member)
DESCRIPTION OF SYMBOLS 9 Excitation coil 10 1st support shaft 11 2nd support shaft 12 Case member 14 Pointer 15 Stopper means 15a 1st projection part 15b 2nd projection part 17 Display board EP1-11 Engagement point M Instrument apparatus

Claims (2)

A first support shaft;
A rotor magnet pivotally supported by the first support shaft and magnetized on the outer peripheral surface along the rotation direction;
A rotor gear pivotally supported on the first support shaft so as to rotate coaxially with the rotor magnet;
A second support shaft;
A first gear portion that is supported by the second support shaft and meshes with the rotor gear, and a second gear that is supported by the second support shaft so as to rotate coaxially with the first gear portion. An intermediate gear having,
A third support shaft;
An output gear pivotally supported by the third support shaft and meshing with the second gear portion;
A case that houses at least the rotor magnet, the rotor gear, the intermediate gear, and the output gear, and supports the first, second, and third rotating shafts;
An excitation coil that rotates the rotor magnet in response to an excitation signal input;
A magnetic member that urges the rotor magnet in a predetermined rotational direction when in the non-excitation state without the excitation signal input,
The output gear is provided with a movable contact portion, and the case is provided with a fixed contact portion for stopping rotation of the third support shaft by contacting the movable contact portion. A stepping motor for an instrument comprising the rotor gear, the intermediate gear, and the output gear coupled so that the movable contact portion presses the fixed contact portion by the rotational biasing force of the magnetic member acting on the rotor magnet. In
The intermediate gear is configured to be assembled after the rotor gear and the output gear so that the second gear portion meshes with the output gear before the first gear meshes with the rotor gear,
An instrument stepping motor, wherein the number of teeth of the first gear portion is set to a natural number times the number of teeth of the second gear portion. The instrument stepping motor according to claim 1, wherein the rotor magnet is directly driven by the exciting coil.

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