JPS61295885A - Brake unit of dc motor - Google Patents

Abstract

PURPOSE:To improve the positional accuracy of an output shaft by shortcircuiting between both terminals of a DC motor when the motor is deenergized to generatively brake the motor, thereby immediately stopping the output shaft. CONSTITUTION:When a brush 9 is slidably contacted with switch patterns 5, 6 to close a switch 10, a transistor 14 is interrupted, and an output shaft and the brush 9 are rotated together with a motor 1. When the brush 9 arrives at the cutout of the pattern 6, the switch 10 is opened, and the motor is rotated by an inertia. At this time, the transistor 14 is conducted by a current generated in the motor 1, the motor 1 is shortcircuited between both terminals to generatively brake the motor 1.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a DC motor used in office automation equipment, etc., and when power to the DC motor is cut off, the DC motor rotating due to inertia can be immediately stopped. The present invention relates to a braking device for a DC motor for braking.

(Prior Art) Figures 6 and 7 show the configuration and operation of a conventional positioning mechanism using a DC motor. 1 is a DC motor (hereinafter referred to as a motor) with a worm 3 attached to the tip of a rotating shaft 2. ), 4 is a DC power supply (hereinafter referred to as power supply) whose anode is connected to the positive pole of the motor 1, 5 is an annular switch pattern connected to the negative pole of the motor 1, and 6 is arranged concentrically around the outer periphery of the switch pattern 5. This switch pattern 6 is an arc-shaped switch pattern having a cutout portion.This switch pattern 6 is connected to the cathode of the power source 4. Reference numeral 7 denotes an output shaft that is integrally attached with a worm gear 8 that meshes with the worm 3 and a brush 9 that makes sliding contact with the switch patterns 5 and 6. The brush 9 and the switch patterns 5 and 6 constitute a switch 10. Patterns 5 and 6 function as fixed contacts of switch 10, and brush 9 functions as a movable contact piece of switch 10.

In the conventional example configured in this way, while the brush 9 is in contact with the switch patterns 5 and 6.

Since the switch patterns 5 and 6 are short-circuited by the brush 9 and the switch 10 is turned on, the output shaft 7 and the brush 9 rotate together with the motor 1 in the direction of the arrow. Since the output shaft 7 and the brush 9 are in sliding contact with the motor 1, the output shaft 7 and the brush 9 continue to rotate together with the motor 1.

However, when the brush 9 reaches the notch of the switch pattern 6, the gap between the switch patterns 5 and 6 is cut off.
Since the switch 10 is in the open state, the motor 1 stops, and the output shaft 7 and the brush 9 also stop. Therefore, by changing the installation location of the cutout portion of the switch pattern 6.

The amount of rotation of the output shaft 7 can be controlled arbitrarily.

(Problem to be Solved by the Invention) However, even if the brush 9 reaches the notch in the switch pattern 6 and the switch 10 is opened, the motor 1 continues to rotate due to inertia, so the output shaft 7 also rotates. Continuing on, there was a problem in that the positioning accuracy of the output shaft 7 deteriorated, and when the voltage of the power source 4 fluctuated, the amount of rotation also changed due to the inertia of the motor 1, which further deteriorated the positioning accuracy of the output shaft 7. Therefore, in order to solve this problem, a stopper mechanism (not shown) was added to the rotating part and the output shaft 7
Although it is possible to improve the positioning accuracy, adding the stopper mechanism reduces the output torque, speed, etc. of the output shaft 7, so there is a problem that the output efficiency of the output shaft 7 is significantly reduced.

The present invention has been made in view of such problems, and provides a braking device for a DC motor that immediately stops a DC motor rotating by inertia by electrical means when power to the DC motor is cut off. The purpose is to

(Means for solving the problem) Connect the DC power supply and DC motor when the DC power supply is energizing, and short-circuit both terminals of the DC motor when the DC motor is de-energized. A braking device for a DC motor that automatically switches to a DC motor is connected between a DC power source and a DC motor.

(Function) If the current to the DC motor is cut off and the terminals of the DC motor rotating by inertia are short-circuited and the current output from the DC motor is fed back to the DC motor, the DC motor will function as a generator. Since the output shaft is braked, the output shaft also immediately stops rotating.

(Examples) Below, nine embodiments of the present invention will be described in detail with reference to the drawings.

1 to 3 show the structure and operation of an embodiment of the present invention, and the same reference numerals as those in FIGS. 6 and 7 indicate the same parts, and 11 indicates the same parts. Motor 1 at one end
A resistor 13 whose other end is connected to the positive pole of the resistor 12 and a resistor 13 connected to the resistor 12 at the other end, an NPN type resistor whose base is connected to the connection point of the resistor 12 and the resistor 13, whose collector is connected to the positive pole of the motor 1, and whose emitter is connected to the negative pole of the motor 1, respectively. The braking device consists of a transistor 14 and a diode 15 whose anode is connected to the negative electrode of the motor 1 and whose cathode is connected to the resistor 12.The anode of the power source 4 is connected to the positive electrode of the motor 1, and the cathode of the power source 4 is connected to the switch 1.
0 to the connection point between the resistor 12 and the cathode of the diode 15.

In this embodiment configured in this way, the transistor 14
The base-emitter voltage V. The values of the resistors 12 and 13 are set in advance so that the voltage is about 0.6V or less. Then, when the brush 9 is in sliding contact with the switch patterns 5 and 6 and the switch 10 is turned on, there is no conduction between the collector and emitter of the transistor 14, and the second
Since the circuit shown in the figure forms a circuit equivalent to the conventional circuit shown in FIG. 7, the output shaft 7 and brush 9 rotate together with the motor 1 in the direction of the arrow. However, when the brush 9 reaches the notch in the switch pattern 6, the switch IO is opened and the motor 1 is not energized, but the motor 1 continues to rotate due to inertia, so the current generated in the motor 1 is braked. Therefore, the resistor 13 is energized, but the diode 15 prevents the resistor 12 from being energized, so the transistor 14 becomes conductive and the voltage between the collector and emitter of the transistor 14, that is, the motor 1 The circuit shown in FIG. 2 forms a circuit equivalent to the circuit shown in FIG. 3. Therefore, immediately after the brush 9 reaches the notch of the switch pattern 6, the motor 1 functions as a generator, the motor 1 is braked, and the output shaft 7 is immediately stopped together with the motor 1.

4 and 5 show the structure and operation of other embodiments of the present invention.
A PNP type transistor 16 is used instead of the N type transistor 14, and the base of the transistor 16 is connected to a resistor 12 whose one end is connected to the negative pole of the motor 1 and a resistor 13 whose one end is connected to the positive pole of the motor 1. At the point, the emitter is connected to the positive pole of the motor 1, and the collector is connected to the negative pole of the motor 1, and the anode of the diode 17 is connected to the resistor 13, and the cathode is connected to the positive pole of the motor 1, respectively.
Further, the anode of the power source 4 is connected to the connection point between the resistor 13 and the anode of the diode 17, and the cathode of the power source 4 is connected to the negative electrode of the motor 1 via the switch 10.

In this embodiment configured in this way, when the brush 9 is in sliding contact with the switch patterns 5 and 6 and the switch 10 is turned on, there is no conduction between the collector and emitter of the transistor 16, as shown in FIG. Since the circuit shown in FIG. 7 forms a circuit equivalent to the conventional circuit shown in FIG. 7, the output shaft 7 and brush 9 rotate together with the motor 1 in the direction of the arrow. Also, when the brush 9 reaches the notch of the switch pattern 6.

The switch IO is opened and the motor 1 is not energized (JaI), but the motor 1 continues to rotate due to inertia.
The current generated by the motor 1 flows into the braking device 11. Therefore, the resistor 12 is energized, but the diode 17 prevents the resistor 13 from being energized, so the transistor 16 becomes conductive and the voltage between the collector and emitter of the transistor 16, that is, between both terminals of the motor 1, is turned on. When shorted, the circuit shown in FIG. 4 forms a circuit equivalent to the circuit shown in FIG. For this reason.

Immediately after the brush 9 reaches the notch of the switch pattern 6, the motor 1 functions as a generator, and the motor 1 is braked, and the output shaft 7 as well as the motor 1 are immediately stopped.

(Effects of the Invention) As explained above, according to the present invention, when the power supply from the DC power source to the DC motor is cut off, both terminals of the DC motor are short-circuited, and the DC motor rotating by inertia generates electricity. Since braking is applied, the output shaft can be immediately stopped regardless of fluctuations in the voltage of the DC power supply, which has the effect of improving the positional accuracy of the output shaft. Also, since the DC motor and output shaft are braked without using any mechanical means, no mechanical load is applied to the DC motor.
This has the effect that the output efficiency of the output shaft does not decrease.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a positioning device equipped with an embodiment of the present invention, FIG. 2 is a circuit diagram of the positioning device shown in FIG. 1,
Figure 3 is an equivalent circuit when the switch in Figure 2 is turned off and the DC motor starts rotating due to inertia, Figure 4 is another circuit diagram of the positioning device shown in Figure 1, and Figure 5 is the equivalent circuit when the DC motor starts rotating due to inertia. Figure 4 is an equivalent circuit when the switch is shut off and the DC motor starts rotating due to inertia, Figure 6 is a perspective view of a conventional positioning device, and Figure 7 is a circuit diagram of the positioning device shown in Figure 6. be. 1...DC motor, 4...DC power supply, 10.
... Switch, 11... Braking device, 12.13...
Resistor, 14.16... Transistor, 15.17
··· diode. Patent Applicant: Matsushita Electric Industrial Co., Ltd. 19 Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] Two resistors connected in series, a base connected to a connection point between the two resistors, a collector connected to one terminal of the two resistors, and an emitter connected to the other terminal of the two resistors via a diode. It consists of a transistor and
A connection point between the collector of the transistor and the resistor and a connection point between the diode and the resistor are connected to a DC power supply via a switch, and a connection point between the collector of the transistor and the resistor and an emitter of the transistor and the A braking device for a DC motor, characterized in that a connection point with a diode is connected to the DC motor.