Motor

Abstract

The axial direction of a worm wheel is defined as a motor short-transverse direction, and a plane orthogonal to the motor short-transverse direction is defined as a motor flat plane. An imaginary plane contacting a first end of a sensor magnet in a motor short-transverse direction and parallel with the flat plane is defined as a first imaginary plane. An imaginary plane contacting a second end of the sensor magnet in the motor short-transverse direction and parallel with the flat plane is defined as a second imaginary plane. A control circuit board is provided with a rotation detecting element that detects rotation of the rotary shaft of the motor. The control circuit board is arranged to be parallel with or inclined relative to the flat plane, and is provided between the first and second imaginary planes.

The invention claimed is: 
     
       1. A motor comprising:
 a motor unit includes a rotary shaft; 
 a speed reduction mechanism that includes a worm shaft and a worm wheel, wherein the worm shaft is arranged coaxially with the rotary shaft and is integrally rotational with the rotary shaft, and the worm wheel is meshed with the worm shaft unit provided at an output side of the motor unit and comprising a worm wheel; 
 a sensor magnet that rotates integrally with the rotary shaft; and 
 a connector module that includes a connector portion for establishing an electrical connection between the outside and the motor unit and a tabular control circuit board provided with a rotation detecting element that detects rotation of the sensor magnet, wherein 
 an axial direction of the worm wheel is defined as a motor short-transverse direction, 
 a plane orthogonal to the motor short-transverse direction is defined as a flat plane of the motor, 
 the sensor magnet has a first end in the motor short-transverse direction and a second end opposite to the first end, 
 an imaginary plane contacting the first end and being parallel with the flat plane is defined as a first imaginary plane, 
 an imaginary plane contacting the second end and being parallel with the flat plane is defined as a second imaginary plane, and 
 the control circuit board is arranged to be parallel with or inclined relative to the flat plane and is located between the first and second imaginary planes 
 a tabular board provided with a rotation detector that detects rotation of the sensor magnet, wherein 
 the worm wheel has a rotation axis that is parallel with a thickness direction of the motor; 
 the motor has a flat plane that is orthogonal to the thickness direction of the motor; 
 the board extends parallel with the flat plane of the motor and outwardly in a radial direction of the rotary shaft; and 
 the sensor magnet has a first end in the thickness direction of the motor and a second end opposite to the first end, and the rotation detector is located within a range of the length of the sensor magnet in the axial direction and between a first imaginary plane that contacts the first end of the sensor magnet and a second imaginary plane that contacts the second end of the sensor magnet. 
 
     
     
       2. The motor according to  claim 1 , wherein the rotation detecting element is located between the first and second imaginary planes detector is configured to detect a magnetic flux in a circumferential direction of the sensor magnet and a magnetic flux in the radial direction of the sensor magnet. 
     
     
       3. The motor according to  claim 1 , wherein
 the control circuit board is located at a position shifted in the motor short-transverse direction relative to an imaginary straight line that is parallel with the flat plane and intersects an axis of the rotary shaft at right angle, and 
 the rotation detecting element is located on a side of the control circuit board that faces the imaginary straight line board is located between the first imaginary plane and the second imaginary plane. 
 
     
     
       4. The motor according to any one of  claim 1 , wherein the rotation detecting element is mounted on the control circuit board by the surface-mount technology. 
     
     
       5. The motor according to claim  4 , wherein
 a tangent line of an outer circumference of the sensor magnet orthogonal to both first and second imaginary planes is defined as a sensor magnet tangent line and 
 when the sensor magnet tangent line traverses the control circuit board as viewed along the axis of the rotary shaft, an end portion of the control circuit board is located on a side of the sensor magnet tangent line that corresponds to the sensor-magnet 1, further comprising 
 the speed reduction unit provided at the output side of the motor unit, 
 a connector module that includes a connector portion for establishing an electrical connection between the outside and the motor unit, wherein 
 the board is provided on the connector module, and 
 the connector module is attached to a housing of the speed reduction unit inwardly in the radial direction of the rotary shaft. 
 
     
     
       6. The motor according to  claim 1 , wherein
 the connector module includes a second board that is parallel with the control circuit board and faces the control circuit board in the motor short-transverse direction,   the control circuit board and the second board are electrically connected to each other,   the second board has on it a switch circuit that generates a drive current to be supplied to the motor unit, and   the control circuit board has on it a control circuit that controls the switch circuit.   
     
     
       7. The motor according to  claim 6 , wherein
 the switch circuit is a relay circuit, and   a clearance between the control circuit board and the second board in the motor short-transverse direction is set to be smaller than a height dimension of the relay circuit.   
     
     
       8. The motor according to  claim 1 , wherein
 the motor unit further includes:   a gear housing that is assembled with the motor unit and accommodates the speed reduction mechanism, which outputs rotation of the rotary shaft after reducing the speed of the rotation; and   a second board that faces the control circuit board in a surface-to-surface manner and is electrically connected with the control circuit board,   the connector module is attached to the gear housing,   electrical components are provided on the facing surfaces of the control circuit board and the second board, and   the electrical component on the control circuit board and the electrical component on the second board are shifted in a board planar direction so as not to interfere with each other.   
     
     
       9. The motor according to  claim 8 , wherein
 an insertion portion is formed in at least one of the control circuit board and the second board, and   the insertion portion receives in it the electrical component provided on the other board.   
     
     
       10. The motor according to  claim 8 , wherein
 the gear housing has a flat shape that is thin in the motor short-transverse direction, and   the control circuit board and the second board are arranged to face each other in the motor short-transverse direction.   
     
     
       11. The motor according to  claim 8 , wherein a width of the second board in a board planar direction is within a width of the control circuit board in a board planar direction as viewed in an attaching direction of the connector module. 
     
     
       12. The motor according to claim 1, wherein
 the rotation detector is secured on the board, thereby reducing the distance between the rotation detector and the sensor magnet to allow a magnetic force of the sensor magnet to be reduced without deteriorating performance of the rotation detection, and   the rotation detector in the form of a rectangular prism, said rectangular prism having a pair of opposing sides exhibiting the largest surface areas of said prism and wherein one of said opposing sides faces the board.