JPH02184239A - Motor - Google Patents

Abstract

PURPOSE:To increase allowable temperature rise of a motor and to shorten axial length by fixing a position detector at one end of a ceramic shaft fitted in a hole made at the opposite side of the output of rotary shaft of a motor and holding the position detector through a spring. CONSTITUTION:A hole is made at the opposite side from the output of the rotary shaft 1 of a motor and a ceramic shaft 3 is fitted therein. A position detector 2 is fixed to the other end of the ceramic shaft 3. The position detector 2 is held through a spring 4 against the case 8 of the motor, and contained in a cover 5 fixed through a thermal insulation board 7 to the case 8. Since the heat of motor is not transmitted to the position detector, allowable temperature rise of motor is increased, axial length of motor is shortened and the cost is reduced.

Description

[Detailed Description of the Invention] Industrial Application Fields In recent years, with the automation and intelligence of factory machinery and equipment, electric motors with position detectors attached to various drive shafts of machines have come into widespread use. It has become.

The present invention relates to an electric motor in which a position detector added to the electric motor is directly connected to a rotor shaft.

Conventional technology - A conventional electric motor will be explained below.

FIG. 5 is a partial sectional view of a conventional electric motor, where 12 is the rotor shaft of the electric motor, 13 is a position detector, and 14 is the rotor shaft 12.
15 is a cover that holds the position detector 13; 16 is a motor body; 1;
Reference numeral 7 denotes a heat insulating plate that connects the motor body 16 and the cover 15 and thermally insulates them.

The operation of the electric motor configured as described above will be explained below.

The pulse signal generated from the position detector 13 must be generated in complete synchronization with the rotation angle of the rotor shaft 12 of the motor.

Therefore, the torsional rigidity of the coupling 14 that connects the rotor shaft 12 and the position detector 13 must be sufficiently high. In addition, since the position detector 13 is completely fixed to the motor body 16 by the heat insulating plate 17 and the cover 15, the coupling 14 absorbs the deviation in the angle of the eccentric surface that occurs between the rotating shaft 12 and the axis of the position detector 13. It must be something that does.

Usually, the permissible operating range of the electric motor is determined by the temperature rise value of the motor, and is limited by the temperature rise limit value of the electric motor itself or the temperature rise limit value of other parts. In the case of a motor equipped with the position detector of this example, since semiconductor electronic components are normally used inside the position detector, the temperature is generally 70°C.
is considered to be the limit temperature, and in the case of 8 types of allowable temperatures for the motor body, 1
In the case of 30°C Fit, it is lower than 155°C, so the permissible temperature rise value of the motor as a whole is limited by the position detector. Therefore, in order to improve the output of the motor while keeping it compact, it is important to consider how to block the conduction of heat from the motor body, which is the source of heat, to the position detector. In this example, the heat conduction from the motor body 16 is
7 and conducts to the position detector 13.

Further, it is necessary to block the heat from the rotor shaft 12 with the coupling 14, and a coupling having a structure in which leaf springs are stacked has to be used.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, a coupling that satisfies the above-mentioned performance is required to connect the rotor shaft of the electric motor and the position detector, so that the axial length of the electric motor becomes long. This had the problem of being expensive because it required sufficiently high torsional rigidity.

The present invention solves the above-mentioned problems, and aims to provide an electric motor that can shorten the axial length of the motor, improve torsional rigidity, and further reduce the price.

Means for Solving the Problems To achieve this object, the electric motor of the present invention uses a second shaft with low thermal conductivity in the connecting part of the position detector, and holds the position detector to the electric motor with a spring. It is structured like this.

Effect This configuration allows the rotor shaft of the motor and the rotation shaft of the position detector to be firmly fixed, improving torsional rigidity and synchronizing the signal from the position detector and the rotational position of the rotor shaft of the motor. , and can block heat conduction from the rotor shaft.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a partial sectional view of an electric motor in one embodiment of the present invention. In Fig. 1, ■ is the rotor shaft of the electric motor, 2 is the position detector whose shaft is hollow, 3 is the second shaft made of ceramic with low thermal conductivity, and 4 is the position detector 2 connected to the electric motor. A fixing spring, 5 a cover for protecting the position detector, 6 a motor body, and 7 a heat insulating plate that connects the motor body 6 and the protective cover 5 and thermally insulates them.

The operation of the electric motor according to the embodiment of the present invention constructed as described above will be explained below.

The signal generated from the position detector 2 is transmitted to the rotor shaft 1 of the motor.
However, in this embodiment, the rotor shaft 1 and the second shaft 3 made of ceramic are completely integrated by bonding, shrink fitting, etc. The mechanical rigidity is the same as the rigidity of the material itself, and is sufficiently higher than the torsional rigidity of the conventional example using a coupling. Similarly, since the second shaft 3 and the position detector 2, which has a hollow shaft, are mechanically integrated using set screws, the mechanical rigidity is sufficiently high to prevent deviation from the signal period. It can be prevented.

Furthermore, by fixing the position detector 2 to the electric motor at the outermost diameter side of the position detector 2 with a spring 4, surface runout due to misalignment of concentricity can be absorbed by the deflection of the spring.

An example of the structure of the spring is shown in FIG. Since the second shaft 3 is made of ceramic with low thermal conductivity, conduction of heat generated from the motor body can be suppressed and temperature rise of the position detector can also be reduced.

As described above, according to this embodiment, the second shaft made of ceramic is integrated with the rotor shaft of the electric motor, a position detector is attached to the second shaft, and it is fixed to the electric motor with a spring. , it is possible to cut off the conduction of heat from the electric motor, and it is possible to widen the allowable operating temperature range of the electric motor. Furthermore, since the rotor shaft and the rotating shaft of the position detector are integrally coupled, the torsional rigidity of the shaft is improved and the characteristics can be improved. Further, since no coupling is used, the axial length required for the coupling can be shortened, and the overall length of the electric motor can be shortened.

Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows a partial sectional view of a second shaft used in an electric motor in another embodiment of the invention. In FIG. 3, 8 is a portion made of ceramic having low thermal conductivity, and 9 is a portion made of metal such as iron or aluminum, and both are connected by shrink fit, adhesive, or the like. Furthermore, by cutting and polishing the outer diameter of both ends of the shaft,
The coaxiality is precisely finished.The second embodiment is constructed by replacing the second axis with the second axis shown in FIG.

Next, a third embodiment will be described with reference to the drawings.

FIG. 4 shows a partial sectional view of the second shaft of the electric motor in another embodiment of the present invention. In Figure 4, 10
11 is a portion made of ceramic having low thermal conductivity, and 11 is a portion made of high-strength material such as steel or carbon, and the two are connected by shrink fitting, adhesion, or the like.

The third embodiment is constructed by replacing the second axis with the second axis shown in FIG.

The second shaft of the electric motor configured as described above has a high strength material arranged at the center of the shaft, so that the shaft strength is improved.
By attaching the shaft to the rotating shaft of the electric motor, the strength of the shaft portion to which the position detector is attached can be improved.

As described above, according to this embodiment, unlike the first embodiment and the second embodiment, it is possible to improve the shaft strength of the second shaft, so it is not necessary to attach a heavier position detector. This makes it possible to improve characteristics such as increasing the number of pulses of the position detector.

Effects of the Invention The present invention provides a second layer with low thermal conductivity in the connecting part of the position detector.
By providing the shaft, heat conduction from the electric motor can be cut off, so the allowable temperature rise of the electric motor can be increased and the electric motor can be made smaller. In addition, by firmly fixing the motor shaft and position detector with the second shaft, torsional rigidity can be improved, and since the position detector is fixed with a spring, a coupling is not required, allowing for shortening in the axial direction and This has the effect of lowering the price and makes it possible to realize an excellent electric motor.

[Brief explanation of the drawing]

1 is a partial sectional view of an electric motor according to an embodiment of the present invention, FIG. 2 is a perspective view of an example of the configuration of the spring 4 shown in FIG. 1, and FIG. A partial cross-sectional view of the embodiment,
FIG. 4 is a partial sectional view taken along the second axis of FIG. 1, and FIG. 5 is a partial sectional view of a conventional electric motor. 1.12...Rotor shaft, 2,13...
Position detector, 3...Second axis, 4...
Spring, 5, 15... Cover, 6, 16...
...Electric motor, 7,17...Insulation board, 8,10.
...Ceramic part, 9...Metal part, 11
...High strength part, 14...Coupling. Name of agent: Patent attorney Shigetaka Awano and 1 other person 1-11th Kyoko Furuko 2-11 Salon Kenkei 3-11 20th Axis 12-11 Kaoru H Koroko Kori 3-a #, earthenware 6 --- electric motor

Claims (3)

[Claims] (1) A rotor consisting of a first shaft with a hole of a predetermined depth at the end of the shaft on the side opposite to the output shaft, and a rotor made of ceramic that fits into the hole of the first shaft. An electric motor comprising: a second shaft; a position detector having a hollow shaft inserted and fixed to the other end of the second shaft; and a spring holding the position detector. (2) The electric motor according to claim 1, wherein the second shaft has an outer peripheral portion at both ends made of metal for a predetermined length. (3) The electric motor according to claim 1, wherein the center portion of the second shaft is made of a high-strength member.