JPH01321888A - Governor motor - Google Patents

Abstract

PURPOSE:To reduce the drift of speeds of a motor by forming a bridge of the first, second and third resistors consisting of a wire having the same quality as a rotor coil and a coil provided in the vicinity thereof to compare with a reference voltage. CONSTITUTION:A coil 23 wound on a rotor core is connected to a lead wire 26 through commutator bars 24a, 24b and brushes 25a, 25b fixed to a rotary strap 21. The first resistor 31 is formed of a wire having the same quality as that of the wire forming the rotor coil 23 and is mounted in the vicinity of the rotor coil 23 to connect to a lead wire 32. One of lead wires 26 and 23 is connected, and the second and third resistors R4 and R5 are connected between the other of them to form a bridge. Voltage at a connecting point of the resistors R4 and R5 is compared with reference voltage which is not illustrated to control the rotation of a motor 30. When the motor 30 starts to enhance a resistance value of the coil 23 by Joule heat, a value of the resistor 31 also increases accordingly, and the balance of the bridge is maintained. According to the constitution, the drift of speeds of the motor is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a governor motor used in a floppy disk device used as an external storage device of a computer.

Conventionally, in this type of governor motor, attention has been paid to the fact that the generated back electromotive force is proportional to the rotational speed, and a bridge circuit is configured with a coil and a plurality of passive detection means (for example, resistors) to eliminate the above-mentioned back electromotive force. The voltage was kept constant and the rotational speed was controlled constant.

FIG. 2 is a configuration diagram showing a conventional governor motor.

In FIG. 2, 1 indicates a motor.

2 is a first resistor connected between the negative end of the winding coil (not shown) of the motor 1 and the ground, and 3 is a first transistor, the collector of which is connected between the negative end of the winding coil of the motor 1 (not shown) and the ground. The emitter is connected to the power supply.

4.5 is the second .4.5 connected in series as a passive detection means.
A third resistor is connected between the collector of the first transistor 3 and the ground of the motor 1. connected in parallel to the first resistor 2; A detection voltage is detected from the connection point P1 between the third resistors 4 and 5.

6 shows a reference voltage generator connected to a power supply, which supplies a stable reference voltage to the first . It is output to the second output terminals 6a and 6b.

7 is a fourth resistor, 8 is a variable resistor, and the fourth resistor 7.
The variable resistor 8 is connected in series, and the reference voltage generator 6
1st. Second output terminal 6a.

6b, and one end of the fourth resistor 7 is connected to a connection point between the winding coil of the motor 1 and the first resistor 2.

A capacitor 9 is connected between the slider of the variable resistor 8 and the ground, and a predetermined reference voltage is detected from a connection point P2 between the capacitor 9 and the slider of the variable resistor 8.

Reference numeral 10 indicates a comparator, the inverting terminal of which is supplied with the detection voltage of the connection point P1, and the non-inverting terminal of which the reference voltage of the connection point P2 is supplied.

11 indicates a second transistor, with a comparator 10 at its base.
The collector is connected to the base of the first transistor 3, and the emitter is connected to ground.

Reference numeral 12 indicates a control circuit composed of the first resistor 2 to the second transistor 11.

Next, the operation of the above conventional example will be explained.

In FIG. 2, the comparator 10 compares the detected voltage at the connection point P1 with the reference voltage at the connection point P2 and outputs the output to the base of the second transistor 11, and then outputs the output to the base of the second transistor 11.
and controls the rotation speed of the motor 1.

In this way, even in the conventional governor motor described above, the winding coil of the motor 1, the bridge circuit composed of the first to third resistors 2, 4, and 5, and the reference voltage of the connection point P2 are used to reverse the polarity of the motor 1. By keeping the electromotive force constant, the rotation speed of the motor 1 can be controlled to be constant.

Problems to be Solved by the Invention However, in the above conventional governor motor, the motor 1
The first resistor 2 connected in series to the winding coil is mounted on the control circuit 12 and disposed outside the motor 1, so the resistance value of the first resistor 2 depends on the resistance temperature of the winding coil. It becomes impossible to follow changes (in particular, temperature rise inside the motor 1), and it becomes impossible to match the resistance value of the winding coil and the resistance value of the first resistor 2.

Therefore, the ratio between the resistance value of the winding coil and the resistance value of the first resistor 2 cannot be kept constant against temperature changes in the internal and external environments of the motor 1, and the rotational speed of the motor 1 drifts. There was a problem.

The present invention solves such conventional problems, and aims to provide a governor motor that can reduce the drift of the motor rotation speed regardless of temperature changes in the internal and external environments of the motor. It is something to do.

Means for Solving the Problems In order to achieve the above object, the present invention includes a first resistor connected in series with the winding coil, which is made of the same material as the winding coil of the motor, in the vicinity of the winding coil. This is what was installed.

Therefore, according to the present invention, the first resistor connected in series with the winding coil is made of the same material as the winding coil, and is arranged near the winding coil. The temperature coefficients of resistance of the first resistor and the first resistor are approximately equal, and the ratio of the resistance values of the wire-wound coil and the first resistor is constant.

Embodiment FIG. 1 is a sectional view showing a governor motor according to a first embodiment of the present invention.

In FIG. 1, 21 is a shaft, 22 is a rotor core fixed to the shaft 21, 23 is a winding coil wound around the rotor core 22, and 24a and 24b are commutators fixed to the shaft 21, respectively. Commitator 24a, 2
Both ends of the winding coil 23 are connected to each of the coils 5b.

25 a and 25 b each indicate a brush, and the current supplied from the lead wire 26 is passed to the commutator 24 a.

It is supplied to the winding coil 23 via 24b.

27 is a magnet disposed to face the rotor core 22, 28 is a bearing portion, 29 is a case that supports the shaft 21 via the bearing portion 28, and a brush 25a.

25b, magnet 27, etc. are attached.

Reference numeral 30 indicates a motor composed of a shaft 21 to a case 29.

Reference numeral 31 indicates a resistor (corresponding to the first resistor 2 in FIG. 2) connected in series with the winding coil 23 of the motor 30, and is made of the same material as the winding coil 23, for example, copper. It is arranged near 23.

A lead wire 32 is connected to both ends of the resistor 31, and one end of the lead wire 32 is connected to one end of the lead wire 26.

Note that illustration of a control circuit corresponding to the control circuit 12 shown in FIG. 2 is omitted.

Next, the operation of the above embodiment will be explained.

In the above embodiment, the current from the lead wire 26 flows through the brushes 25a, 25b and the commutator 24a.

24b to the winding coil 23.

Therefore, the current supplied to the winding coil 23 and the magnet 2
According to Fleming's left-hand rule in the magnetic circuit configured by 7, the winding coil 23 generates a rotational force, so the shaft 21 rotates.

Note that the direction of rotation of the shaft 21 is determined by the direction of the current applied to the lead wire 26, and the direction of rotation of the shaft 21 is determined by the direction of the current applied to the lead wire 26.
The brushes 25a and 25b switch the direction of the current flowing through the winding coil 23 to keep the rotation direction constant.

As described above, when a current flows through the winding coil 23, the winding coil 23 generates heat due to Joule heat, so the resistance value changes.

Since the Joule heat generated from the winding coil 23 is transferred to the resistor 31, the resistance value of the resistor 31 changes in the same way as the winding coil 23, and the winding coil 23 also changes in response to temperature changes in the external environment. changes in the same way.

Furthermore, since the resistance temperature coefficients of the wire-wound coil 23 and the resistor 31 are equal, the ratio of their resistance values is constant.

Therefore, rotational drift of the motor 30 can be reduced.

Note that in the above embodiment, both lead wires 26. 32 is connected, but one of both lead wires 26.32 may be connected inside the case 29. In this case, the total number of both lead wires 26.32 is reduced from 4 to 3. By doing so, it is possible to reduce costs.

Further, the resistor 31 may be arranged in a gap between the rotor core 22 and the magnet 27, etc.

Effects of the Invention As is clear from the above embodiments, the present invention has a first resistor connected in series to the winding coil made of the same material as the motor winding coil, and is arranged near the winding coil. Since the temperatures of the wire-wound coil and the first resistor are almost the same, and the resistance temperature coefficients of both are also the same, the ratio of their resistance values remains almost constant regardless of temperature changes, reducing rotational drift. It has the effect of being able to.

Further, since the first resistor can be made of only copper, it can be manufactured at a lower cost than when it is made of a resistor having a specific temperature coefficient of resistance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a governor motor according to an embodiment of the present invention, and FIG. 2 is a configuration diagram showing a conventional governor motor. 4... Second resistor, 5... Third resistor, 12... Control circuit, 23... Winding coil, 30... Motor, 31...first resistor.

Claims (1)

[Claims] A bridge circuit configured by connecting a motor winding coil and a first resistor made of the same material as the winding coil in series on one side, and connecting a second and third resistor in series on the other side. and a control circuit that compares a reference voltage with a detected voltage at a connection point of the second and third resistors to compensate for rotational drift of the motor, and connects the first resistor to the winding coil. The governor motor is located near the.