JP3287167B2 - DC commutator motor drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving circuit for a small DC commutator motor using a DC power source such as a battery.

[0002]

2. Description of the Related Art Conventionally, DC commutator motors have been widely used in many fields because of their high efficiency, small size and large starting torque. When the circuit for driving the DC commutator motor is operated at a low voltage, a low current and continuously at a constant speed, the DC commutator motor is generally directly connected to a DC power supply such as a battery.

The characteristics of the DC commutator motor are that the brush and the commutator are operated in contact with each other, so that the DC commutator motor is efficient and a small motor can be used. However, there is a disadvantage that friction powder is generated due to friction between the brush and the commutator motor.

[0004]

When the DC commutator motor rotates at a high speed, the friction powder scatters around, but when the motor continues to rotate at a low speed, the friction powder accumulates in the gap between the commutators. I will.

[0005] Depending on the operating atmosphere (temperature and humidity) of the motor, a large amount of friction powder is generated, and an energizing route (bridge) is formed between the commutators, causing a decrease in the number of revolutions and an increase in the current. This causes an increase in the battery and a problem such as the battery being consumed in a short time.

An object of the present invention is to provide a drive circuit for a DC commutator motor, which solves the above-mentioned problems and extends the life of the motor.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above objects, the present invention has two substantially equal power supplies connected in parallel to a DC commutator motor and each connected in series to said power supplies. A rectifier, current detecting means, and a switch for connecting the two power supplies in series to a DC rectifier motor;
Means for keeping the switch means conductive for a certain period of time.
Storage means .

[0008]

According to the present invention, the switch means is normally non-conductive and the current flowing to the DC commutator motor is supplied by connecting two power supplies in parallel.

However, when the current value detected by the current detecting section exceeds a predetermined value, the switch means is turned on, and
Two power supplies are connected in series to double the voltage supplied to the motor and to break the bridge formed between the commutators.

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIG. 1 and 2 are first and second two DC power supplies, respectively. A first rectifier 3 and a first current detector 4 are inserted between the first power supply 1 and a DC commutator motor 8 serving as a load. In addition, a second rectifier 5 and a second current detector 6 are inserted between the second power supply 2 and the DC commutator motor 8. Reference numeral 7 denotes a semiconductor switch as switch means inserted between the plus terminal of the first power supply 1 and the minus terminal of the second power supply 2. The semiconductor switch 7 is provided by the first current detection unit 4 and the second current detection unit 6. The semiconductor switch 7 is configured to close when the detected current exceeds a predetermined value.

In the above configuration, in a normal operation, the semiconductor switch 7 is in a non-conductive state, and the first power supply 1
The DC current commutator motor 8 is driven via the first current detector 4 and the first rectifier 3, and at the same time, the second current detector 6 and the second rectifier 5 are also supplied from the second power supply 2. The DC commutator motor 8 is driven via the first power supply, and the first and second power supplies are connected in parallel and used.

[0012] The DC commutator motor 8 has its driving conditions,
The surrounding environment generates wear powder due to friction between the commutator and the brush. The abrasion powder accumulates and a bridge is formed between the commutators. In such a case, the drive current of the commutator motor 8 increases. This current increase is monitored by the first and second current detectors 4 and 6, and when this value exceeds a predetermined value, the semiconductor switch 7 becomes conductive. As a result, the first power supply 1 and the second power supply 2 are connected in series, and a voltage twice as high as that in the normal operation is applied to the commutator motor 8. Therefore, the bridge between the commutators is burned out by applying twice the voltage,
The current does not increase, the semiconductor switch 7 is turned off, and the commutator motor 8 is applied with a normal voltage.

In order to reliably perform the bridging operation of the bridge, the semiconductor switch 7 may be provided with a storage means in order to keep the conduction state for a certain period of time.

(Embodiment 2) FIG. 2 is a diagram showing another embodiment of the present invention. 1st and 2nd rectifier 3 in FIG.
2 and 5 are replaced by a PNP transistor 9 and an NPN transistor 11, respectively, in FIG.
The first and second current detectors 4 and 6 in FIG. 1 are composed of resistors 10 and 12 inserted in series with the collectors of respective transistors 9 and 11 in FIG.
Has been replaced by

The operation of the embodiment of FIG. 2 is the same as that of the embodiment of FIG. 1, except that an increase in current due to a bridge formed between the commutators is detected as a voltage drop across resistors 10 and 12, and It is transmitted to the switch.

[0016]

As described above, according to the present invention, when conduction occurs between the commutators of the motor, the DC power that has been applied to the motor in a parallel connection in a normal state becomes a series connection,
By applying twice the normal voltage, the conductive wear powder bridging between the commutators of the motor is burned off to cut off the conduction and the life of the motor can be greatly extended.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a drive circuit of a DC commutator motor according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a drive circuit of a DC commutator motor according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st power supply 2 2nd power supply 3 1st rectifier 4 1st current detection part 5 2nd rectifier 6 2nd current detection part 7 Semiconductor switch 8 Motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-4790 (JP, A) JP-A-6-153460 (JP, A) JP-A-57-138844 (JP, A) JP-A-48-48 72618 (JP, A) JP-A-47-21820 (JP, A) JP-A-48-1815 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 5 / 00-5 / 26 H02P 7/00-7/34

Claims (1)

(57) [Claims] A DC commutator motor and a DC commutator motor.
Two substantially equal first and second power supplies connected in parallel to the first power supply and a positive terminal of the first power supply.
The base connected to the DC commutator motor has a current detection resistor.
PNP transformer consisting of a collector connected via a resistor
And an edge connected to the negative terminal of the second power supply.
Positive terminal of the second power supply via a mitter and a base resistor
The base connected to the DC commutator motor detects the current.
NPN transformer consisting of a collector connected through a resistor
Transistor, the first power supply, and the second power supply,
Switch means connected in series to the current commutator motor
And holding the switch means in a conductive state for a certain period of time.
Storage means, and is detected by the current detection resistor.
When the current value exceeds a certain value, the switch means
A drive circuit for a DC commutator motor, wherein the drive circuit conducts for a predetermined time .