JPH06153461A - Dc servomotor - Google Patents

Abstract

PURPOSE:To eliminate the wear scraps of brushes in a housing produced by the wear of the brushes. CONSTITUTION:Suction nozzles 13a, 13b and 13c whose tips are positioned close to the surfaces of contactors 15 and 20 provided in a DC servomotor, a fan 14 directly linked with the rotary shaft 18 of a rotor 10, a housing 12b in which the fan 14 is housed and three-way valves 21 and 22 which are attached to pipings linked with the holes 24a and 24b which are provided in front and rear of the fan 14 are provided. The suction nozzles 13a, 13b and 13c are connected to the valves 21 and 22 with the pipings through a filter 23. A vacuum pump composed of the fan 14 and the housing 12b is operated by the rotation of the rotor 10 and the valve 21 or 22 is opened and closed in accordance with the direction of the rotation and dusts adhering to the contact surfaces of the commutators 15 and 20 are sucked by the suction nozzles 13a, 13b and 13c to keep the contact surfaces always clean.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC servomotor, and more particularly to a DC servomotor which inputs a brush to a rotor.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing an example of an operation system of a DC servo motor. Generally, the operation system of the DC brush servo motor is a grown loop system as shown in FIG. That is, the output from the speed setter 9 is input to the control unit 8 and the rotation command is output to the DC servo motor. As a result, the DC servomotor 1 rotates at the set rotation speed and is transmitted to the load 5. At this time, the tacho-generator built in the DC servo motor 1 detects the rotation fluctuation due to the fluctuation of the load, and as a speed detection signal, the control unit 8
Give feedback to. Then, the control unit 8 compares it with the setting signal and sends an output corresponding to the difference to the DC servo motor to keep the rotation speed constant.

FIG. 3 is a sectional view of a conventional DC servo motor. A DC servo motor whose rotation is controlled by the closed loop system is, for example, as shown in FIG. 3, a rotor 10 having a tag generator and a rotor,
The housing 12 that wraps the rotary shaft of the rotor 10 so as to be exposed and the commutator 15 of the rotor 10 comes into contact with the rotor 1.
A brush 16 that transmits a current that gives a rotational force to 0, and a brush 11 that detects the rotation speed of the rotor 10 from the commutator 20.
Had.

Further, the brushes 11 and 16 respectively have springs 17 at their rear end portions in order to apply a constant contact pressure.
Is installed, and when the brushes 11 and 16 wear due to long-term operation and the length becomes short, replace with a new brush,
I was trying to drive normally.

[0005]

In this conventional DC servo motor, wear debris is generated as the brush that controls the input and output is worn. The abrasion debris adheres to the surface of the commutator to increase the contact resistance with the brush, which makes the electric power supply to the rotor unstable, and also makes the detection accuracy of the tachogenerator unstable, making it difficult to maintain the rotation accuracy.

An object of the present invention is to provide a DC servo motor which can maintain the rotation speed with high accuracy without causing an increase in contact resistance even if brush abrasion debris is generated.

[0007]

A DC servomotor of the present invention is attached to a rotary shaft of a rotor, and a suction nozzle whose tip is disposed in the vicinity of a contact surface of a portion of a rotor which extends inside a housing and contacts a brush. A fan having a plurality of blades, a housing that encloses the fan, a three-way valve that has at least two remaining ports and a port that communicates with the holes in the front and rear of the fan, and this valve. And a pipe connected to the remaining one port and connected to the suction nozzle.

Another servo motor is characterized in that a filter is provided in the middle of the pipe.

[0009]

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

FIG. 1 is a sectional view showing an embodiment of a DC servo motor of the present invention. This DC servo motor is shown in FIG.
As shown in FIG. 5, the suction nozzles 13a, whose arrow ends are arranged in the vicinity of the commutators 15 and 20 for sucking wear debris,
13b and 13c, and a rotating shaft 18 extending from the rotor 10.
Attached to the fan 14, a housing 12b that encloses the fan 14, and a three-way valve 21 that is connected to pipes that communicate with the holes 24a and 24b of the housing 12b.
And 22 are provided, and the valves 21 and 22 and the suction nozzles 13a, 13b, and 13c are connected by piping. Otherwise, it is the same as the conventional example.

Next, the operation of this DC servo motor will be described. First, when the rotor 10 rotates clockwise, the valve 22 is opened by the rotation direction command signal.
And the exhaust port 25a are closed and the valve 21 is closed with the pipe port 24b Exhaust port 25b
Pass through.

By the rotation of the fan 14 directly connected to the rotor 10, the suction nozzles 13a, 13b and 13c suck in the abrasion debris generated in the vicinity of the commutators 15 and 20. The abraded debris passes through the pipe and the filter 23.
At this time, wear debris is accumulated in the filter 23, and the purified air passes through the pipe, is introduced into the valve 21, and is discharged to the outside of the housing 12b through the exhaust port 25b of the valve 21.

When the rotor 10 rotates counterclockwise, the counterclockwise rotation signal opens the valve 21 to the intake side, and the suction nozzle 13 is rotated as the fan 14 rotates.
Inhaled by a, 13b and 13c. The air passes through the piping and the filter 23, passes through the valve 22 and the housing 1
It is discharged to 2b.

Thus, regardless of the direction of rotation of the DC servo motor, the suction nozzles 13a, 13b and 13c are
Since it collects wear debris by means of
0 keeps clean and keeps contact resistance constant. If necessary, a bell jar for storing a desiccant is attached in the middle of the piping so that the dryness of the air in the housing is always maintained.

[0015]

As described above, according to the present invention, by providing the nozzle for sucking the atmosphere in the vicinity of the commutator surface inside the housing and the fan type vacuum pump for performing the suction operation of the nozzle, the inside of the DC servo motor is provided. The contact surfaces of the brush and the commutator on the rotation input side and the tacho generator output side are maintained in a good state, the increase in contact resistance due to abrasion dust is eliminated, and the rotation accuracy of the DC servo motor is always stabilized.

[Brief description of drawings]

FIG. 1 is a sectional view of a DC servomotor showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an operation system of a DC servo motor.

FIG. 3 is a cross-sectional view of a DC servo motor showing a conventional example.

[Explanation of symbols]

 1 DC Servo Motor 5 Load 8 Control Unit 9 Speed Setting Device 10 Rotor 11, 16 Brushes 12, 12a, 12b Housing 13a, 13b, 13c Suction Nozzle 14 Fan 15, 20 Commutator 17 Spring 19 Magnet 21, 22 Filter 24a, 24b Hole 25a, 25b exhaust port

Claims (2)

[Claims] 1. A suction nozzle whose tip is arranged in the housing in the vicinity of a contact surface of a portion of a rotor which comes into contact with a stretching brush, a fan having a plurality of blades attached to a rotating shaft of the rotor, and this fan. A three-way valve that has a housing that encloses the housing and a hole that communicates with the holes in the front and rear of the fan and that has at least two remaining openings, and that is connected to the remaining one opening of this valve and A DC servomotor having a pipe connected to a suction nozzle. 2. The DC servomotor according to claim 1, wherein a filter is provided in the middle of the pipe.