JP2001078392A - Stepping motor with sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately mount a sensor for detecting the magnetic pole of a rotor for the phase of the induced voltage of a stepping motor at a fixed electrical angle. SOLUTION: A fitting part 18a for fitting the center of a sensor 17 is provided in a line for connecting the center of arbitrary yoke pole teeth in a yoke assembly to that of the rotor of a motor, the center of the sensor is used as a base point, a plurality of sensor fitting parts 18b are provided at a position that is equal to an integral multiple of the magnetic pole division angle of the rotor or 1/2, 1/3, and 1/5 for obtaining the output. Furthermore, by a hybrid Hall element where a plurality of Hall chips (sensor films) are achieved in one mold of the Hall element, the accuracy of a sensor output phase is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor mounting structure for a sensor-equipped stepping motor used for information equipment and the like.

[0002]

2. Description of the Related Art In recent years, stepping motors have been used in many information-related devices such as printers, facsimile machines, image scanners, copiers, and laser beam printers, FA devices such as machine tools, electric devices for vehicles, and the like.
It is widely used in a very wide range of fields such as various home appliances represented by white goods. This is largely because stepping motors are very inexpensive, and speed control and positioning control can be realized by extremely simple operations.

Conventionally, as a sensor mounting structure of a stepping motor with a sensor, those described in Japanese Patent Application Laid-Open No. 9-253139 and Japanese Utility Model Application Laid-Open No. 62-135558 are generally known. 9 and 10 show the structure of a conventional stepping motor with a sensor. Further, there is also a content in which control of a stepping motor is described as sensorless as in Japanese Patent Publication No. 6-46880.

FIG. 9 shows a conventional example (1). 51
Denotes a drive winding of the stepping motor, and 52 denotes a yoke portion configured to cover the drive winding, and is composed of a pair of magnetic bodies formed in a comb shape for each winding. Reference numeral 53 denotes a rotor configured to face the inner periphery of the yoke. The rotor is composed of an output shaft 54, a ring-shaped motor magnet 5 having a plurality of N-pole and S-pole magnetized magnets, and a medium such as a resin connecting the magnets. Reference numeral 56 denotes a magnetic sensor, which is attached to the printed circuit board 7 separately attached to the stepping motor by electric conduction means, and is configured to face a sensor magnet 58 separately attached with a certain gap. By the rotation of the rotor, a voltage corresponding to the magnetic force of the N pole / S pole is output from the magnetic sensor through the wiring of the printed circuit board.

FIG. 10 shows a conventional example (2). This example has a structure in which a sensing mechanism such as a slit disk 65 having a plurality of minute slits is provided on an output shaft 64 of the stepping motor, and the optical sensor 66 cyclically outputs the presence or absence of the slit. This sensor structure is commonly referred to as an optical encoder,
The structure is generally diverse in each field. It has the advantages of relatively easy installation, large sensor output, and easy to obtain various types of output, but also position adjustment of the slit disk and rotor to obtain sensor output corresponding to the rotor. However, there are disadvantages such as difficulty in performance, variation in performance, and an increase in cost.

In the example of Japanese Patent Publication No. 6-46880, control of a stepping motor is devised as sensorless, but the induced voltage and the substitute sensor signal necessarily have the same phase, which is convenient for control. .

However, the substitute sensor signal using the non-excited winding has many basic problems such as malfunction due to the influence of noise / instantaneous normal / reversal, and has the possibility of being compact, resulting in complicated control. Inevitable
There are drawbacks such as the method of using the motor is limited as compared with the case with the sensor.

[0008]

These sensor structures have advantages and disadvantages in terms of sensor mounting, output size, adjustment workability, sensor resolution, cost, and the like.

In FIGS. 9 and 10, the function of sensing the rotation of the output shaft of the motor may be considered to be the same. However, in the example of FIG. 9, the position of the magnetic pole of the motor magnet fixed to the rotor can be directly detected, but in the example of FIG. 10, the position of the slit disk and the position of the magnetic pole of the rotor can be detected. Must be adjusted in a separate process. As the resolution of sensing the slit disk increases, the adjustment range dimension (or angle) becomes narrower, making the operation extremely difficult, and adversely affecting the stability of cost and performance.

Further, it is difficult to adjust the torque generating position (induced voltage) of the motor and the position of the sensor output as a problem common to the two examples. In general, a sensor signal is indispensable for motor control. Although a sensorless device has been devised, it does not reach the performance of a motor that obtains and controls sensor signals at this stage. It is important that these sensor output signals have an electrical phase relationship with a motor torque generation position (which can be considered as an induced voltage) within a predetermined range. This phase relationship becomes more important as the content of the control becomes more complicated and the accuracy increases, and it has been demonstrated that the better the phase accuracy is, the more the controllability of the motor is improved and the performance is stabilized.

However, in the case of the above-described general sensor structure, it is understood that a great deal of labor (man-hours) is required to accurately fix the torque generation position and the sensor output. In order to construct a stepping motor with a sensor, as shown in the conventional example, multiple components must be combined.However, the accumulation of component accuracy and combination accuracy in a general sensor structure causes large variations in motor performance. appear. A new sensor structure needs to be developed in order to guarantee the position accuracy of the sensor with little effort.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a position detecting means for detecting a position of a rotor of a stepping motor and outputting a position detecting signal. In order to provide a stepping motor structure with a sensor, wherein one of a plurality of induced voltages to be generated and one of the position detection signals of the rotor are always in-phase output, in the stepping motor with a sensor, The end face magnetic pole position of the motor magnet is detected with a constant gap, and at least one of the position detecting means for outputting a position detection signal is positioned by a part of the yoke coupling resin which is integral with the yoke portion of the stepping motor, The structure where the position corresponding to the sensor center of the positioning is arranged concentrically with the center of the pole teeth of the yoke piece. The provided by claim 2.

Further, the outer circumference of a magnetic drum which is a magnetic output generating means attached to a rotor of the stepping motor and a position detecting means which is arranged substantially concentrically with the center of the pole teeth of the yoke piece is constant. Claim 3 provides a structure which is installed to face with a gap.

According to a fourth aspect of the present invention, a plurality of Hall element chips (sensor films) are provided on the sensor for detecting the position of the rotor in the stepping motor with the sensor, the basic step angle of the stepping motor or the magnetic pole angle of the rotor. It is an object of the present invention to use a hybrid Hall element in which a plurality of elements are arranged at an interval of an integral multiple of 1/2 or 1/3 or 1/5, and an integrated element is formed by resin molding.

According to these inventions, the sensor output of the present invention for detecting the torque generation position (induced voltage) of the motor and the position of the rotor can be obtained in a highly accurate phase relationship.
The controllability of the motor can be significantly improved with a small amount of labor.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A stepping motor with a sensor according to a first aspect of the present invention has the following requirements. (A) Any one phase of the induced voltage of the stepping motor and any one phase of the position detection signal obtained from the rotor of the stepping motor are always in-phase output.

A stepping motor with a sensor according to a second aspect has the following requirements. (A) The requirements set forth in claim 1 are provided. (B) Further, one of the sensors for generating the position detection signal of the rotor of the stepping motor is fixed to the yoke coupling resin integrally formed in the yoke portion, so that it is shifted from the pole teeth of the yoke piece. Without the sensor, the induced voltage generated in accordance with the position of the yoke pole teeth also obtains an output in the same phase as the position of the rotor of the stepping motor.

According to a third aspect of the present invention, a stepping motor with a sensor has the following requirements. (A) The requirement described in claim 2 is provided. (B) The rotor, which is the means for detecting the rotor position of the stepping motor, is provided with a magnetism generating means dedicated to position output, thereby improving the stability of the output value.

A stepping motor with a sensor according to a fourth aspect has the following requirements. (A) The requirements described in claims 2 and 3 are provided. (B) The use of a hybrid Hall element in which a plurality of Hall element chips (sensor films) are formed as an integrated element by resin molding in order to obtain a plurality of rotor positions for a sensor for detecting the position of the rotor. It is possible to obtain the phase relationship between each sensor output with higher accuracy.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a correlation between a position signal obtained from a motor magnet magnetic pole of a rotor of a stepping motor and a phase of an induced voltage generated by a driving winding according to a first embodiment of the present invention. Represent. In this figure, Ea and Eb represent the induced voltage of each phase, and Cs-A and Cs-B represent the sensor output obtained from the magnetic pole of the motor magnet of the rotor. It can be clearly seen that Ea and Cs-A are output in phase. Regardless of the stepping motor, it is well known that the control of the motor depends on the positional relationship between the position of the rotor of the motor and the induced voltage generated by the drive winding. In particular, in the case of a stepping motor, which is a synchronous motor, if the positional relationship is largely deviated, control will not be performed, and loss of synchronization will be caused, resulting in a fatal defect such as a stop of the motor.

FIGS. 2 and 3 show a specific positioning structure of the stepping motor with a sensor according to the first embodiment of the present invention. FIG. 2A is a half sectional view of a structure for obtaining a magnetic output of a magnet end face of a rotor of a stepping motor, and FIG. 2B is a layout view of a Hall element. FIG.
FIG. 4 is a diagram in which a yoke portion of the motor is cut in a circle so that the positional relationship between the magnetic sensor and the yoke can be easily understood. 1 is a drive winding of the stepping motor, and 2 is a yoke configured to cover the drive winding. The yoke portion is composed of a plurality of comb-shaped yoke pole teeth made of four pieces of magnetic material, and is integrally formed by the yoke coupling resin portion 11. This integrated product of the yoke part and the resin part is called a yoke assembly. In this yoke assembly, a bearing holding portion 13 that supports a bearing 12 for holding the output shaft 4 of the stepping motor is integrated, and the motor is configured such that they cover the rotor 3 of the stepping motor. ing. The rotor of the stepping motor includes a motor magnet 5 and a rotor coupling resin portion 14 for holding the motor magnet on a shaft. The rotor magnet of the stepping motor has a configuration in which the end face of the motor magnet faces the bearing holding portion of the yoke assembly. Become.

In the yoke assembly, the yoke position is fixed by the resin, so that the center 15
Center point 1 of the magnetic sensor 6 (6a, 6b) on the extension of
The magnetic sensor fitting portion 18a capable of holding the outer shape of the magnetic sensor or the lead comb 20 is provided on the resin portion of the yoke assembly so that the yoke 7 can be held. Further, as shown in FIG. 3, the magnetic sensor fitting portion 18a has an integral multiple of the basic step angle of the stepping motor or 1/2, 1/3 or 1/5 of the magnetic pole angle of one rotor. Magnetic sensor fitting portion 18 similar to integer multiple angular position HALL
b, and by providing a plurality of magnetic sensors 6a and 6b, a plurality of cyclic rotor positions having a constant phase amount corresponding to the position of the induced voltage can be obtained as sensor outputs.

(Embodiment 2) FIGS. 4 and 5 show a rotor 3 of a stepping motor in which a sensor magnet 19 (hereinafter referred to as a magnetic drum) dedicated to sensor output is formed concentrically with the motor magnet 5. This is an example in which a magnetic sensor 6 (6a, 6b) is configured to face the cylindrical side surface of the magnetic drum. The yoke assembly has the same configuration as that of the first embodiment, but a magnetic drum integrated with the rotor is built in, so that the bearing portion 20 formed in the yoke coupling resin portion protrudes as compared with the first embodiment. become.

Each pole of the magnetic drum is formed by magnetizing the same position at the same time as the motor magnet. The attachment of the magnetic sensor has a structure in which a magnetic sensor fitting portion is provided on an extension of the center of the yoke as in the first embodiment. In this example, the yoke coupling resin portion has a cylindrical side surface. Therefore, the phase relationship between the motor induced voltage and the sensor output is determined according to the first embodiment.
Is exactly the same as The feature of this example is that the pole center of the magnetic drum and the center of the sensor are easily mechanically aligned. Compared with the first embodiment, visual confirmation can be easily performed.

As a result, the output value, output distortion, and output offset are stabilized. In particular, the output value is 1.5 to 1.5 times that of obtaining the magnetic flux from the magnetic pole on the end face of the motor magnet and outputting it as a sensor output.
The output value becomes three times larger, and the margin for the noise / temperature characteristics increases. This is because the magnetic flux in the magnetization direction is obtained, and the magnetic flux on the end face corresponds to the leakage magnetic flux.

(Embodiment 3) FIG. 6 shows a configuration in which a Hall element in which a plurality of Hall element chips 21 are integrated with a magnetic sensor 6 is used. A plurality of Hall element chips are arranged at an integer multiple of the basic step angle of the stepping motor or an integral multiple of 1/2, 1/3, or 1/5 of the magnetic pole angle of one rotor. The center of the Hall element chip at the location is aligned with the extension of the center of the yoke of the yoke assembly, and the sensor output output from this Hall element is based on the output of the same phase as the induced voltage of the motor. It is possible to take out the output indicating the magnetic pole position as a plurality of outputs from the same element.

Since the position between the Hall element chips is configured when the Hall element is created, it is possible to obtain a very high precision of the phase relationship between the outputs of the plurality of sensors. Example 1
The phase accuracy can be improved by 5 degrees or more in electrical angle as compared with FIGS. Furthermore, a motor having a plurality of Hall elements, such as a small-diameter motor, in which a plurality of hall elements cannot be provided has an extremely effective advantage, and greatly contributes to downsizing of the motor and space saving of equipment. The mounting configuration of the hall element having the plurality of hall chips may be as shown in the first and second embodiments.

(Embodiment 4) FIGS. 7 and 8 show an embodiment relating to the position of the magnetic sensor with respect to the magnetic pole of the motor magnet. In a structure having a yoke made of a magnetic material facing the motor magnet, magnetostriction occurs in the magnetic flux generated from the end face of the motor magnet. Therefore, the center of the thickness tm of the end face of the motor magnet cannot be the maximum magnetism. Further, the thickness tm of the magnet is not effectively magnetized due to the configuration of magnetization.

In FIG. 8, the thickness t of the end face of the magnet is shown.
The figure which measured the sensor output in the outer diameter direction of the magnet from the center of m is shown. The output is greater when the sensor is located on the outer diameter side than the center of the magnet.

This embodiment is characterized in that the center 17 of the sensor is arranged between the center 16 of the thickness tm of the end face of the magnet and the outer diameter of the magnet.

[0032]

As is clear from the above description, the stepping motor with sensor and the small motor according to the present invention have the following advantages. (A) Since the induced voltage of the motor and the sensor output obtained from the magnetic pole of the rotor are generated in the same phase, the controllability is improved. Excellent. (B) Since the fitting portion of the magnetic sensor is formed at the time of component configuration with respect to the yoke position of the stepping motor, the in-phase accuracy with the induced voltage is high. (C) Since the fitting part of the magnetic sensor is formed in a part of the motor component, the height of the motor can be made extremely thin in the case of a structure in which magnetism is obtained from the magnet end face of the rotor of the motor. (D) For products that require a high output stability of the magnetic sensor,
The output can be stabilized by the magnetic drum structure integrated with the rotor. Also in this case, the phase relationship between the induced voltage and the sensor output can be configured very simply. (E) By configuring a plurality of Hall element chips (sensor films) in one Hall element mold, a sensor output with even higher phase accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between an induced voltage of a motor and a magnetic pole output of a rotor according to an embodiment of the present invention.

2A is a half sectional view of a structure for obtaining a magnetic output of a magnet end face of a rotor of a stepping motor, and FIG.

FIG. 3 is a layout diagram of a plurality of Hall elements of the motor.

FIG. 4 is a sectional view of a structure in which a magnetic drum is added to a rotor of a stepping motor to obtain a magnetic output on a side surface thereof.

FIG. 5 is a layout diagram of a plurality of Hall elements and a yoke of the motor.

FIG. 6 is a structural diagram of obtaining a magnetic output by a hybrid Hall element in which a plurality of Hall element chips (sensor films) are formed in one mold.

FIG. 7 is a diagram showing a position of a motor magnet end surface of a rotor of a stepping motor and a position of a center of a magnetic sensor.

FIG. 8 is a diagram showing data at the time of performing FIG. 7;

FIG. 9 is a sectional view of the structure of a stepping motor with a sensor using a conventional magnetic sensor.

FIG. 10 is a sectional view of a structure of a stepping motor with a sensor using a conventional optical sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive winding 2 Yoke part 3, 53 Rotor 4, 54, 64 Output shaft 5, 55 Motor magnet 6a, 6b, 56 Magnetic sensor 7, 57 Printed circuit board 11 Yoke coupling resin 12 Bearing 13 Bearing holding part 14 Rotor coupling Resin 15 Center of yoke piece 16 Center of thickness of magnet end face 17 Center of magnetic sensor 18a, 18b Sensor fitting part 19, 58 Magnet for sensor (magnetic drum) 20 Lead comb 21a, 21b Hole chip (sensor film) 22 Hybrid Hall element 51 Drive Winding of Stepping Motor 52 Yoke 65 Slit Disk 66 Optical Sensor

Claims (5)

[Claims] A stepping motor having a plurality of phases of driving windings; an exciting means for supplying electric power for exciting the driving windings; a magnetic pole position of a rotor of the stepping motor; The rotor magnetic pole is detected at a position where one of the induced voltages corresponding to a plurality of phases generated from the drive winding and one of the magnetic pole position detection signals of the rotor always output the same phase. A stepping motor with a sensor, comprising a positioning mechanism for a magnetic sensor. 2. A yoke coupling resin part, wherein at least one of position detecting means for detecting a magnetic pole position of a motor magnet end face of a rotor with a certain gap and outputting a position detection signal is integrated with a yoke part of a stepping motor. A stepping motor with a magnetic sensor facing the end face of a motor magnet, wherein the sensor center of the position detecting means to be positioned is positioned concentrically with the center of the pole teeth of the yoke piece. 3. A rotor of a stepping motor having a magnetic sensor center provided on a yoke coupling resin portion formed integrally with the center of the pole teeth of the yoke piece and disposed concentrically with the center of the pole teeth. A stepping motor with a magnetic sensor, wherein the stepping motor has a fixed gap and is attached to the output shaft. 4. A plurality of Hall element chips (sensor films) are provided on a magnetic sensor for detecting the position of a magnetic pole of a rotor.
A hybrid Hall element, which is disposed at an interval of an integral multiple of 1/2 or 1/3 or 1/5 of the basic step angle of the stepping motor or the magnetic pole angle of the rotor and integrated with a resin mold, with respect to the motor magnet end face. A stepping motor with a magnetic sensor, wherein a plurality of magnetic output signals can be obtained from one Hall element by facing each other or outside the circumference of a magnetic drum. 5. A magnetic sensor structure for generating a magnetic output signal by obtaining a magnetic force from a magnetic pole of a motor magnet end face of a rotor in a stepping motor with a sensor.
A stepping motor with a sensor, characterized in that the center of the magnetic sensor is located on the outer periphery side and within the outer periphery from the center of the thickness of the motor magnet.