JPH0828997B2 - Drive - 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 device, and more particularly, it comprises a driving machine having a coil for energizing the coil to generate a driving force, and a driving circuit for energizing and driving the driving machine. The present invention relates to a drive device.

[0002]

2. Description of the Related Art In a driving device of this type, for example, a driving device using a stepping motor as a driving device, a method for cooling a heat generating portion of the device such as a driving element such as a power transistor of a driving circuit (hereinafter referred to as a power element) Conventionally, two methods have been adopted.

The first method is a natural cooling method in which a large heat radiating member corresponding to the amount of heat generated, a so-called heat sink, is attached to the power element and the like, and cooling is performed by utilizing convection of air.

In the second method, the heat sink of the power element is miniaturized, a cooling fan, that is, a fan by a motor is separately provided, and the fan is forcibly air-cooled through the heat sink to cool the heat sink. It is a forced air cooling system that improves cooling efficiency.

[0005]

However, the above two cooling methods have the following drawbacks. First, in the case of natural cooling, the cooling effect is generally the heat dissipation area of the heat sink and its mounting direction (direction determined by air convection).
The heat generation by the power element is significant in the motor drive circuit, and a large heat sink is required. However, increasing the size of the heat sink (generally made of an aluminum material) causes problems such as an increase in cost, an increase in the size of the device, and restrictions on the mounting method (direction, etc.).

On the other hand, in the case of the forced air cooling method, the flow of air is forcibly formed, so that the degree of freedom in the mounting direction of the device can be obtained. However, since it requires a power supply circuit for driving the cooling fan, it has the following drawbacks.

The space obtained by miniaturizing the heat sink will be used by the power circuit of the fan,
Cannot downsize the device.

The power supply circuit of the fan itself becomes a new heat source.

Since the forced cooling is continued by driving the fan even when the motor is not driven and the motor driving circuit does not generate heat or has a small amount of heat, power consumption is wasted and the life of the fan is shortened. I will end up.

Even if the cost increase due to the cooling fan can be offset by the cost reduction due to the miniaturization of the heat sink, the cost increase due to the power supply circuit will occur.

Therefore, an object of the present invention is to eliminate the above-mentioned conventional drawbacks in the drive device of this type, to efficiently cool the device, to save power, and to further reduce the size and cost of the device. To provide a configuration that can be achieved.

[0012]

In order to solve the above-mentioned problems, according to the present invention, in a drive device of the type described above, which has an electric cooling means such as a fan for cooling a heat generating portion, A configuration is provided in which a circuit for driving the cooling means is provided by the counter electromotive force generated in the coil when the coil is de-energized or switched when the driving machine is driven.

[0013]

According to this structure, the cooling means can be driven by the back electromotive force generated in the coil of the driving machine when the energization of the coil of the driving machine is cut off or switched when the driving machine is driven. Cooling can be performed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. Here, a motor drive device using a stepping motor as a drive machine is illustrated.

FIG. 1 shows the overall circuit configuration of the motor drive device of the embodiment. In FIG. 1, reference numeral 1 is a stepping motor of a driving machine, which is a 5-phase motor having five coils L1 to L5 connected in a so-called pentagon. Reference numeral 2 is a power supply circuit that supplies electric power for driving the motor 1.

Reference numerals T1 to T10 are power transistors for driving the motor 1, and a small heat sink (not shown) is attached to each of them. A drive voltage is applied from the power supply circuit 2 to the coils L1 to L5 of the motor 1 through the transistors T1 to T10,
The transistors T1 to T10 are selectively turned on and off by the control of the transistor drive circuit 3 including an IC, whereby the energization of the coils L1 to L5 is switched, the so-called excitation phase is switched, and the motor 1 is driven. .

Diodes D1 to D10 are connected between the collectors and emitters of the transistors T1 to T10, respectively. Further, the power supply circuit 2 and the transistors T1 and T
Diodes D11 to D15 are also inserted in the power supply lines between each of T3, T5, T7, and T9.

On the other hand, reference numeral 4 is a cooling fan, which cools the heat generating portions of the devices such as the transistors T1 to T10 and the power supply circuit 2 in particular. A fan drive circuit 5 including a transistor T11, a Zener diode ZD, and diodes D21 to D25 is provided to drive the motor of the fan 4. This circuit 5 protects elements such as power transistors from the back electromotive force generated in the coil of the motor drive circuit when switching the excitation phase of the motor coil, and acts as an electrical damper in an FBC (flyback) circuit. Control) is a diversion of the circuit.

The respective anode sides of the diodes D21 to D25 are connected to the respective cathode sides of the diodes D11 to D15, and the cathodes of the diodes D21 to D25 are connected to the collector of the transistor T11.
A Zener diode ZD is connected between the collector and the base of the transistor T11. And the transistor T
The collector and emitter of 11 are connected to the connection terminals at both ends of the power supply line of the fan 4.

The physical constitution of the apparatus of this embodiment is as shown in FIG. Control box 6 separate from motor 1
The motor drive circuit 8 including the transistors T1 to T10 shown in FIG. 1 is provided on the circuit board 7 provided in the box 6, and the fan drive circuit 5 is provided therein. The power supply circuit 2 is provided in the box 6 separately from the circuit board 7. The cooling fan 4 is provided on the side wall of the box 6.

Next, the operation of the above configuration will be described. FIG.
In the configuration described above, the transistors T1 to T10 are selectively turned on and off by the transistor drive circuit 3, and the output current of the power supply circuit 2 is sequentially switched and applied to the coils L1 to L5, and the motor 1 is rotationally driven by being energized. To be done. Transistors T1 to T10 are coils L1
Corresponding to .about.L5, there are 5 pairs as indicated by symbols 1φ to 5φ, and the transistors in the pair are turned on / off in reverse when the corresponding coils are energized and deenergized.

Considering the coil L1, the transistor T1 is turned off and the transistor T2 is turned on when energized, and the current from the power supply circuit 2 is applied to the coil L1 in the arrow direction. Conversely, when switching the excitation phase, the transistor T1 is turned on and the transistor T2 is turned off, so that the power supply current is cut off. At this time, the counter electromotive force due to the inductance of the coil L1 causes the current I1 in the same direction as that during energization.
Occurs and becomes a current Iz through the diodes D1 and D21 and flows into the fan drive circuit 5.

At this time, the voltage V1 applied to the motor of the fan 4, that is, the voltage between the collector and the emitter of the transistor T11 is the Zener voltage V of the Zener diode ZD.
z is the voltage VB between the base and emitter of the transistor T11
If the height is higher than the value obtained by adding E, the transistor T11 is turned on and the current I3 flows, so that V1≤VBE + Vz, and the voltage is controlled to a substantially constant voltage and the voltage V is applied to the fan 4.
A current I2 corresponding to 1 flows.

Since the motor 1 is a five-phase motor and is driven by four-phase excitation, the coils L1 to L have an electrical angle of 360 °.
5, the counter electromotive force is generated once, respectively, a total of 5 times, and the voltage V1 and the current I2 applied to the fan 4 by the counter electromotive force are shown in FIG. 3 when the motor 1 is continuously driven at 1 kpps, for example. As described above, the pulse voltage and the current having the duty ratio of 73 to 80% are applied. The voltage V1 is set to about 18V, for example. The higher the step rate corresponding to the rotation speed of the motor 1, the higher the duty ratio. That is, the fan 4 is driven by the PWM (pulse width modulation) method in accordance with the rotation speed of the motor 1 to be rotationally driven, and the heat generating portion of the device can be cooled by blowing air.

According to the present embodiment as described above, the fan is used in comparison with the conventional forced air cooling system, but as described above, the coils L1 to L5 are switched to the coils L1 to L5 by switching the excitation phase when the motor 1 is driven. Since the fan 4 is driven by the generated back electromotive force, the power supply circuit dedicated to the fan 4 is unnecessary.
In addition, the fan drive circuit 5 is a diversion of the FBC circuit as described above, so that the fan drive circuit 5 is not particularly expensive, and the cost can be reduced as a whole.

Further, as described above, the current Iz flowing into the fan drive circuit 5 is controlled by the PWM method to partially (I2).
Is consumed by the fan 4, and the rest (I3) is consumed by the transistor T11 (as originally intended by the FBC circuit). According to the PWM control, when the duty ratio of the voltage of the counter electromotive force is high, that is, when the motor 1 is driven at high speed and the heat generation of the transistors T1 to T10 is remarkable, the pulse width of the drive voltage and the current of the fan 4 is large and the pulse interval is large. Becomes smaller, the fan 4 rotates at a high speed and exhibits a high cooling capacity. On the contrary, when the duty ratio of the voltage of the back electromotive force is low, that is, when the motor 4 is driven at a low speed and the heat generation is small, the fan 4 rotates at a low speed, and the cooling capacity corresponds to the small heat generation. When the motor 1 further stops, the counter electromotive force is not generated and the duty ratio becomes 0, and the fan 4 also stops. That is, when the heat generation stops, the fan 4 also stops.

As described above, the fan 4 is automatically driven by the PWM control system in response to the driving of the motor 1 without using a sensor or the like, and efficient and effective cooling can be performed without waste, and there is no waste of power consumption. . The life of the fan 4 is also extended.

Further, in the prior art, the counter electromotive force of the motor was unnecessarily consumed by the resistors and the transistors in the FBC circuit, whereas this counter electromotive force is used for cooling in the present embodiment. To reduce the waste of.

Furthermore, in this embodiment, since the forced air cooling system is used, the heat sink such as the power transistor can be downsized, and since there is no dedicated power source for the fan 4 and no space for the power source is required, the overall size of the device can be reduced.

As described above, the structure in which the cooling fan is driven by the counter electromotive force of the coil is not limited to the drive device of the motor, but is used as, for example, a printing hammer that hits the characters of a printer, and is intermittent at high speed. It can also be applied to a solenoid drive device driven by the.

[0031]

As is apparent from the above description, according to the present invention, a driving machine having a coil and energizing the coil to generate a driving force, and the energization to drive the driving machine. A drive device comprising a drive circuit, further comprising an electric cooling means for cooling a heat generating portion of the device, wherein the coil is energized when the energization of the coil is cut off or switched when the drive machine is driven. Since a configuration in which a circuit for driving the cooling means is provided by the generated back electromotive force is adopted, a power source dedicated to the cooling means is unnecessary, cooling by the cooling means is not wasted, and can be performed efficiently and effectively,
It is possible to obtain an excellent effect that the power saving and the life of the cooling means can be extended, and further the device can be downsized and the cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a physical configuration of the device.

FIG. 3 is a waveform diagram showing waveforms of a drive voltage and a current of a fan 4 by a fan drive circuit 5 of the same device.

[Explanation of reference numerals] 1 stepping motor 2 power supply circuit 3 transistor drive circuit 4 cooling fan 5 fan drive circuit 6 control box 7 circuit board 8 motor drive circuits D1 to D15, D21 to D25 diodes L1 to L5 coils T1 to T11 transistors ZD Zener diode

Claims (1)

[Claims] 1. A drive device comprising a drive machine having a coil for energizing the coil to generate a driving force, and a drive circuit for energizing the drive machine to drive the drive machine, further comprising heat generation of the device. In a drive device having an electric cooling means for cooling a part, a circuit is provided for driving the cooling means by a back electromotive force generated in the coil when the energization of the coil is cut off or switched when the driving machine is driven. A drive device characterized by the above.