JPS6264246A - Dc servomotor - Google Patents

Abstract

PURPOSE:To save power lines and miniaturize the whole system, by providing the polygonal section of a yoke forming a cylindrical section and the polygonal section, with ventilation flues, a driving circuit for feeding motor current, and a circuit for detecting the motor current. CONSTITUTION:A stator yoke 3 surrounding a rotor 1 with a polygonal section 5 and the following cylindrical section is formed, and the external side of the yoke 3 is surrounded with a casing 17 to be protected. Inside the wall sections 5a of the polygonal section 5, ventilation flues 6 are arranged, and outside the sections 5a, comb-formed salient sections 5b are arranged. In a space between the casing 17 and the polygonal section 5, the servo circuit component parts such as a power IC for a driving circuit, a motor current circuit, a speed generator, and the like (not shown in the drawing) are contained. By this method, cooling effect is improved, and power lines are shortened, and a compact device of less noise is constructed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a relatively large-capacity DC servo motor with an output of too much or more, and in particular, by incorporating a drive circuit, it saves power supply lines, This invention relates to a DC servo motor that reduces costs and noise associated with this.

[Prior Art] As is well known, DC servo motors are widely used in fields such as automatic control because of their excellent features such as easy control and large starting torque.

FIGS. 6 and 7 show the overall configuration of a conventional DC servo motor system. In the figure, DC output from a DC power supply 31 drives and controls a DC servo motor 33 via a drive circuit 32a consisting of four sets of transistors Ql-Q4. The rotation speed of the DC servo motor 33 is detected by the speed generator 34 and fed back to the control circuit 32b. The control circuit 32b controls the pulse width of the transistors Q1 to Q4 using this feedback signal and the motor current detected by the shunt resistor 35 to control the torque of the DC servo motor 33. Note that the drive circuit 32a and the control circuit 32b are connected to the drive device 3.
The DC servo motor 33 rotates in the normal direction when the transistors Q1 and Q4 are conductive, and rotates in the reverse direction when the transistors Q2 and Q3 are conductive.

[Problems to be Solved by the Invention] By the way, in the conventional DC servo motor system described above, a large current is passed between the DC power supply 31 and the drive device 32 and between the drive device 32 and the DC servo motor 33. Since the power line 37 must be connected through the power line 37, the following problems arise.

(1) Since the total length of the power line 37 becomes very long,
The voltage drop due to this power line 37 becomes large, and the loss increases.

(2) For the same reason as (1) above, the weight of the wiring increases.

(3) Due to the large pulsating current flowing through the power line 37,
Radio noise occurs.

In particular, if the installation location of the drive device 32 is limited and it must be installed at a location away from the DC power supply 31 and DC servo motor 33 as shown in FIG.
7 becomes extremely long, and the above-mentioned problems become noticeable.

The present invention was made against this background, and an object thereof is to provide a DC servo motor that solves the above problems.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a yoke having a cylindrical part and a polygonal part, and in which a ventilation passage is formed inside the polygonal part, and the yoke. A field magnetic pole provided on the inner wall,
A rotor rotatably provided within the field magnetic poles, a drive circuit fixed to the outer periphery of the polygonal portion and supplying a motor current to the motor windings, and a detection means for detecting the motor current. are housed in the same casing.

[Function] According to the above configuration, the drive circuit that handles a large current and the current detection means are all built into the DC servo motor, so the power line 37 is connected to the DC power supply 31 as shown in FIG. All you need to do is connect it to the DC servo motor.
The others become lines that conduct a weak current. Therefore, as long as the DC power supply 31 and the DC servo motor are close to each other, all of the above-mentioned problems can be solved.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view showing the structure of a DC servo motor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line ■--■ in FIG. In these figures, l is a rotor, and a yoke 3 having field magnetic poles 2 formed on the inner wall is provided on the outer periphery of the rotor l. This yoke 3 is shown in FIG.
As shown in FIG. 3, it consists of a cylindrical part 4 with a diameter slightly larger than the rotor l, and a polygonal part 5 formed such that the inner wall end is continuous with the outer peripheral end of the cylindrical part 4. The portion 4 and the polygonal portion 5 are integrally formed. A plurality of ventilation passages 6 which are open at both ends are formed in the wall portions 5a forming each surface of the polygonal portion 5, and a plurality of ventilation passages 6 which are open at both ends are formed on the outer periphery of the wall portion 5a to enhance the heat dissipation effect. A comb-shaped protrusion 5b is formed.

Also attached to the outer periphery of the wall portion 5a are drive power ICs (type A) 7a to 7d and output power ICs (type B) 8a to 8d shown in FIG. 4. In this case, an output power IC that consumes a large amount of power
(Type B) 8a to 8d are installed on the upstream side of the ventilation path 6, and are power ICs for drives with relatively low power consumption.
(Type A) 7a to 7d are installed on the downstream side. Further, a pair of opposing support members 9.9 are attached to the other outer periphery of the wall portion 5a, and a linear shunt resistor IO is stretched between the support members 9.9.

Further, a speed generator 11 is fixed to one end side of the rotor l (on the left side in FIG. 1) so as to have a common axis with the rotor 1, and on the outside of the speed generator 11 is a printed card described later. 12
, a cooling fan 13 are installed in order.

In addition, in the figure, 14 is a motor commutator, 15 is a motor brush, and 16 is a receptacle, and these components 1 to 1
5 is housed in one casing 17 and constitutes a DC servo motor 18.

Next, in FIG. 4, the print card 12 consists of four photocouplers 21a to 21d and a current limiter 22, and the outputs of the photocouplers 21a and 21b are connected to a power IC.
(Type A) The outputs of the photo couplers 21c and 21d are supplied to the bases of the resistors 23c and 7b.
It is supplied to each base of power IC (type A) 7c and 7d via 23d.

In addition, a shunt resistor 1 is connected to the input terminal of the current limiter 22.
The obtained motor current detection signal is supplied to both ends of 0, and when an excessive current flows to the motor, the base current of the power IC (type A) 7c, 7d is regulated so that the motor current is limited. It has become. In addition, in the figure, 24 is a thermal switch that is turned off when the motor temperature rises.

FIG. 5 is a block diagram showing the connection relationship between the DC servo motor 18, the DC power supply 31, and the control device 25 according to the above embodiment. First, the DC power supply 31 and the DC servo motor 18 are connected by a power line 37, and 28 VDC as shown in FIG. 4 is supplied to the DC servo motor 18. Further, between the control device 25 and the DC servo motor 18, there is a line 26 for transmitting control signals to the photocoupler 21a to 21d, current supplied to the cooling fan 13, and output signals of the speed generator 11 and the thermal switch 24. is provided. Furthermore, a power supply line 27 is provided from the DC power supply 31 to the control device 25.

According to such a configuration, the drive power ICs (type A) 7a to 7b are controlled by the control signal supplied from the control device 25 to the DC servo motor 18 through the line 26.
is controlled on/off, thereby controlling the output power I
C (type B) 8a to 8d are also turned on/off to control the rotation of the rotor l. When the power ICs 7a, 7d and 8a, 8d are on, the rotor 1 rotates in the normal direction, and when the power ICs 7b, 7c, 8b, 8c are on, the rotor 1 rotates in the reverse direction.

In this case, a large current flows only in the power line 37, and only small currents flow in the other lines 26, 27. Therefore, the DC power supply 31 and the DC servo motor 1
If the installation location is close to power line 3,
7 can be short and produce the desired effect.

Further, the heat emitted from the power ICs 7a to 8d is carried by the air blown from the cooling fan 13, flows through the ventilation passage 6, etc. as shown by arrows in FIG. 1, and is emitted to the outside. In this way, the combination of the cylindrical part 4 and the polygonal part 5 allows the power I
The installation locations for C7a to 8d and the shunt resistor 10 can be secured, and the heat dissipation effect can be enhanced.

[Effects of the Invention] As described above, the present invention has circuit means for handling large currents, such as a drive circuit and motor current detection means, built into the DC servo motor, so that the following effects can be achieved.

(1) Power lines can be saved, and voltage loss and wiring weight can be reduced.

(2) Since the motor brush section and drive circuit, which are the sources of radio noise, are housed in the same casing, noise suppression measures are relatively easy.

(3) Since the drive circuit and the motor unit, which generate a large amount of heat, are housed in the same casing, both can be cooled simultaneously by one cooling fan. Therefore, the number of fans can be saved and
You can save space and reduce costs.

(4) By using highly efficient IC transistors in the drive circuit, the entire servo system can be made smaller and lighter.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the structure of a DC servo motor according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is an external appearance of the yoke of the DC servo motor. Figure 4 is a block diagram showing the electrical configuration of the DC servo motor, Figure 5 is a block diagram showing the power line connection position in the DC servo motor system, and Figure 6 is a conventional DC servo motor system. FIG. 7 is a schematic perspective view showing the configuration of the servo motor system, FIG. 7 is a circuit diagram showing the electrical configuration of the DC servo motor system, and FIG. 8 is a block diagram showing the connection positions of power lines in the DC servo motor system. . l...Rotor, 2...Field magnetic pole, 3.
... Yoke, 4 ... Cylindrical part, 5 ...
... Polygonal part, 6... Ventilation passage, 7a to 7d...
...Power IC (type A) (drive circuit), 8a~
8d...Power IC (type B) (drive circuit)
, lO... Shunt resistance (detection means) 17...
...Casing, 18...DC servo motor.

Claims (1)

[Claims] A yoke having a cylindrical part and a polygonal part and having a ventilation passage formed inside the polygonal part, a field magnetic pole provided on the inner wall of the yoke, and a field magnetic pole rotatably provided within the field magnetic pole. The rotor, a drive circuit fixed to the outer periphery of the polygonal part and supplying motor current to the motor windings, and detection means for detecting the motor current are housed in the same casing. DC servo motor.