JP2000014114A - Motor driving gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To start a motor provided with oil-retaining bearing as an bearing in a short time even under the environment of low temperature. SOLUTION: Prior to starting a motor, temperature around a three-phase brushless motor 11 is detected with a temperature sensor 15. If the detected temperature is equal to or lower than a specified temperature, a control circuit 16 heats the oil-retaining bearing inside the three-phase brushless motor 11 by making a heating current flow from a heating power supply circuit 13 to a driving coil 3. As a result, the viscosity of the lubricant oil of the oilles bearings becomes low. After these processes, the control circuit 16 makes the driving current flow from a brushless motor driving IC 12 to the driving coil 3 to drive the three-phase brushless motor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device, and more particularly to a motor drive device for driving a motor having an oil-impregnated bearing.

[0002]

2. Description of the Related Art Conventionally, in a disk device such as a CD, a CD-ROM, and a DVD, a three-phase brushless motor is used as a spindle motor for rotating a disk. FIG.
FIG. 4 is an operation principle diagram of an inner rotor type brushless motor of a three-phase half-wave energization method. In the figure, D ₁ , D ₂ , D ₃
Are light emitting diodes, which are arranged at an angle of 120 ° to each other around the rotation axis of the motor. F ₁ is a light shielding plate having an opening portion in a part, and is configured to rotate with the motor.

[0003] Q ₁ , Q ₂ , Q ₃ are phototransistors, which block light from the light emitting diodes D ₁ , D ₂ , D ₃ from light shielding plate F _1.
The light is received through the apertures of the respective elements. SB is a light shielding plate F
Reference numeral ₁ denotes a rotating shaft, and Q ₄ , Q ₅ , and Q ₆ are transistors of a drive circuit, and perform a switching action according to the outputs of the phototransistors Q ₁ , Q ₂ , and Q ₃ . L ₁ , L ₂ , L ₃
Are drive coils of the motor, which are arranged with an electrical angle of 120 ° from each other. L _M is a rotor of the motor, which is composed of N-pole and S-pole magnets.

Now, the light shielding plate F₁Is the positional relationship as shown in Fig. 4.
The phototransistor Q in section a_TwoIn the light
Given. At this time, the phototransistor Q_TwoIs on
And a voltage is generated on the emitter side. And this out
Transistor Q _FiveTurns on. to this
Therefore, the driving coil L_TwoIs excited and the rotor L_MClockwise
(Clockwise). As described above, the light shielding plate F₁
Is the rotor L_MRotates with the rotation of the₁Opening
Moves to the position of point C.

Next, when the opening of the light shielding plate F ₁ comes to the position of the point C, the phototransistor Q ₃ is turned on, and the transistor Q _{6 of the} driving circuit is turned on. by this,
Driving coil L ₃ is energized to rotate further clockwise the rotor (clockwise).

When the opening of the light shielding plate F ₁ comes to the position of the point b, the phototransistor Q ₁ is turned on. Phototransistor Q ₁ is if the on transistor Q ₄ become on, the driving coil L ₁ is energized. Accordingly rotor L _M further continues to rotate, eventually circling again reaches the point a.

As described above, the above series of operations are sequentially repeated.
Rotor L by returning_MIs a continuous rotation. this
, The driving coil L of each phase with respect to the rotation angle of the rotor₁,
L_Two, L _ThreeIs as shown in FIG.

Further, many recent brushless motors use a Hall element for position detection, but there are some differences between the number of magnetized poles of the magnet and the position of the Hall element, and the operating principle is the same as described above. .

FIG. 6 is a sectional view showing an outer rotor type brushless motor used as a spindle motor of a disk device such as a CD or DVD. The difference from the above inner rotor type is that there is a drive coil inside the rotor,
Since the cup-shaped rotor is provided so as to wrap around this, the operation principle is the same except that a Hall element is used as the position detection device.

In FIG. 1, 1 is a bracket, and 2 is a stator core. The stator core 2 is fixed to a central portion of the bracket 1, and a drive coil 3 is wound therearound. Reference numeral 4 denotes a rotor, and a rotation shaft 5 is provided at the center thereof so as to rotate integrally. An axial lower end of the rotating shaft 5 is attached to the bracket 1 by a thrust plate 6.
It is supported rotatably. The outer periphery of the rotating shaft 5 is rotatably supported by an oil-impregnated bearing 7 made of a metal in which lubricating oil penetrates a large number of small holes. The oil-impregnated bearing 7 has a cylindrical portion 1a that is set upright from the center of the bracket 1.
Is supported on the inner wall side.

A magnet 8 is fixed to the inner wall of the rotor 4 facing the outer peripheral surface of the stator core 2. This magnet 8
Generates a rotational force for rotating the rotor 4 with respect to the bracket 1 by a magnetic field generated by passing a current through the drive coil 3 wound around the stator core 2. 9 is a rotating shaft 5
Reference numeral 10 denotes a printed circuit board on which wiring is printed.

With the above configuration, the rotating shaft 5 rotates smoothly while being supported by the oil-bearing bearing 7 containing lubricating oil.

[0013]

The oil-impregnated bearing 7
In general, the viscosity of the lubricating oil that has permeated the liquid decreases as the temperature decreases, as shown in FIG. When the viscosity of the lubricating oil increases, the rotational resistance between the rotating shaft 5 and the oil-impregnated bearing 7 increases. Therefore, when the motor is started in a low temperature environment (for example, −20 ° C. or less), the viscosity of the lubricating oil is large and the rotation resistance between the rotating shaft 5 and the oil-impregnated bearing 7 is large. There is a problem that can not be started.

Accordingly, an object of the present invention is to provide a motor drive device that can start a motor reliably in a short time even in a low-temperature environment.

[0015]

SUMMARY OF THE INVENTION According to the present invention, there is provided a motor having an oil-impregnated bearing and a coil, and a motor driving device having a coil driving section for controlling a driving current of the coil. Temperature detecting means, a heating means for supplying a heating current to the coil to heat the oil-impregnated bearing, and a switching control means for switching connection to the coil from the coil driving section to the heating means. This is achieved by a motor drive. That is, with the above configuration, a heating current can be applied to the drive coil prior to starting the motor in a low-temperature environment, and the oil-impregnated bearing can be heated. Can be reliably started in a short time.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a motor drive device according to an embodiment of the present invention. The motor driving device shown in FIG. 1 includes a three-phase brushless motor 11 having an oil-impregnated bearing, a brushless driving IC 12 for supplying a driving current to a driving coil 3 of the three-phase brushless motor 11, and a heating current supplied to the driving coil 3. Heating power supply circuit 13
A switch 14 for switching the connection to the drive coil 3 to the brushless motor drive IC 12 and the power supply circuit 13 for heating, a temperature sensor 15 disposed near the three-phase brushless motor 11, And a control circuit 16 for controlling the operation of the motor 1
7 and a power switch 18.

The three-phase brushless motor 11 has the same structure as the outer rotor type three-phase brushless motor shown in FIG. 6, and includes a driving coil 3, a rotating shaft 5, an oil-impregnated bearing 7, and the like. The brushless motor drive IC 12 includes the control circuit 1
The three-phase brushless motor 11 is driven by supplying a drive current to the drive coil 3 based on a signal such as motor rotation from the motor 6. The brushless motor drive IC 12 has a configuration substantially inside a dotted line shown in FIG. 4, and drives the drive coil 3 according to the output of the phototransistor.

The heating power supply circuit 13 causes the driving coil 3 to generate heat by supplying a heating current to the driving coil 3. The changeover switch 14 is switched by the control circuit 16, and switches the connection to the drive coil 3 between the brushless motor drive IC 12 and the power supply circuit 13 for heat generation. The temperature sensor 15 is installed near the three-phase brushless motor 11, detects a temperature near the three-phase brushless motor 11, and outputs a detection result to the control circuit 16. The control circuit 16 controls the entire device, and switches the switch 14 in accordance with the detection result of the temperature sensor 15 to generate heat in the drive coil 3 before starting at a low temperature, and thereafter, operates the operation unit. The brushless motor drive IC 12 is controlled based on a rotation command input from the CPU 17.

Next, the operation of the motor driving device according to the first embodiment of the present invention will be described. Here, it is assumed that the changeover switch 14 is initially on the brushless drive IC 12 side. FIG. 2 is a flowchart showing the operation of the control circuit 16 in the motor driving device according to the first embodiment of the present invention. First, when the power switch 18 is turned on, the power of the entire apparatus is turned on and the operation starts. Next, it is determined whether the three-phase brushless motor 11 is rotating (step S1). When the three-phase brushless motor 11 is rotating, the rotating operation is continued as it is. In step S1, when the three-phase brushless motor 11 is not rotating, the temperature in the vicinity of the three-phase brushless motor 11 becomes higher than a predetermined temperature (for example, −20 ° C.) based on the detection result of the temperature sensor 15. It is determined whether it is low or high (step S2). If the temperature near the three-phase brushless motor 11 is lower than the specified temperature in step S2, the changeover switch 14 is switched to the power supply circuit 13 for heat generation (step S3). Thereby, the power supply circuit 13 for heat generation
A heating current is supplied to the drive coil 3. The drive coil 3 is
When the heat generation current flows, heat is generated by the resistance of the drive coil 3. When the drive coil 3 generates heat, the heat causes the oil-impregnated bearing 7 in the three-phase brushless motor 11 to be heated, and the viscosity of the lubricating oil of the oil-impregnated bearing 7 also decreases (step S4).

Next, it is determined whether or not a motor rotation command has been input from the operation unit 17 (step S5). If there is no motor rotation command in step S5, step S2
The operation from step S2 to step S5 is repeated until a rotation command is input, and the heat generation of the coil is continued.

If the temperature is higher than the specified temperature in step S2, the process proceeds to step S5, and steps S2 and S5 are repeated until a rotation command is input. If a motor rotation command is input in step S5,
The changeover switch 14 is switched to the brushless motor drive IC 12 side (step S6). Next, the brushless motor driving IC 12 is controlled and the brushless motor driving IC 12 is controlled.
Drives the three-phase brushless motor 11 by supplying a drive current to the drive coil 3 (step S7).

As described above, in the motor driving device according to the first embodiment of the present invention, if the temperature in the vicinity of the three-phase brushless motor 11 is lower than the specified temperature, the heating power supply circuit 13 supplies the driving coil 3 with the heating current. Then, the oil-impregnated bearing 7 is heated to lower the viscosity of the lubricating oil of the oil-impregnated bearing 7. Thereafter, since the motor drive IC 12 supplies a drive current to the drive coil 3, the rotation resistance between the rotating shaft 5 and the oil-impregnated bearing 7 can be reduced, and the three-phase brushless motor 11 can be started reliably.

FIG. 3 is a flowchart showing the operation of the control circuit 16 in the motor driving device according to the second embodiment of the present invention. The configuration of the motor drive device of the second embodiment is the same as the configuration of the above-described first embodiment. However, in the second embodiment, the temperature sensor 15 is wound around the oil-impregnated bearing 7 and directly detects the temperature of the oil-impregnated bearing 7.
The other configuration is the same as that of the first embodiment, and the description is omitted.

First, when the power switch 18 is turned on,
The power of the entire apparatus is turned on and the operation starts. Next, it is determined whether the three-phase brushless motor 11 is rotating (step S11). When the three-phase brushless motor 11 is rotating, the rotating operation is continued as it is. In step S11, when the three-phase brushless motor 11 is rotating / stopping, the temperature of the oil-impregnated bearing 7 inside the three-phase brushless motor 11 is determined based on the detection result of the temperature sensor 15 (for example, It is determined whether the temperature is lower than (−20 ° C.) (step S12). Step S12
When the temperature of the oil-impregnated bearing 7 is lower than the specified temperature, the changeover switch 14 is switched to the heat-generating power supply circuit 13 (step S13). The heating power supply circuit 13 supplies a heating current to the drive coil 3. When the heating current flows, the driving coil 3 generates heat due to the resistance of the driving coil 3. When the drive coil 3 generates heat, the heat causes the oil-impregnated bearing 7 to be heated, and the viscosity of the lubricating oil of the oil-impregnated bearing 7 also decreases (step S14).

Thereafter, in step S15, the heating of the drive coil 3 is continued until the temperature detected by the temperature sensor 15 exceeds the specified temperature. If the temperature of the oil-impregnated bearing 7 exceeds the specified temperature in step S15, the changeover switch 14 is switched to the brushless motor drive IC 12 side (step S16). In step S16, the changeover switch 14
Is switched, and if it is determined in step S12 that the temperature is higher than the specified temperature, it is determined whether a motor rotation command has been input from the operation unit 17 (step S17).
If there is no motor rotation command in step S17, the process proceeds to step 12, and the above-described operations from step S12 to step 17 are repeated until the rotation command is input.

On the other hand, if a motor rotation command is input in step S17, the brushless motor drive IC 12
And the brushless motor drive IC 12 supplies a drive current to the drive coil 3 to start the three-phase brushless motor 11 (step S18).

As described above, in the motor driving device according to the second embodiment of the present invention, if the temperature of the oil-impregnated bearing 7 is lower than the specified temperature, the heat-generating power supply circuit 13 supplies a heat-generating current to the drive coil 3 and The bearing 7 is heated to lower the viscosity of the lubricating oil of the oil-impregnated bearing 7. Thereafter, when the temperature of the oil-impregnated bearing 7 exceeds the specified temperature, the supply of the heating current to the drive coil 3 is stopped.
When the motor rotation command is waited for, and the motor rotation command is input, the brassless motor drive IC 12 supplies a drive current to the drive coil 3, so that the three-phase brushless motor 11 can be started without fail and compared with the first embodiment. Current consumption can be reduced. In the above description of the first embodiment and the second embodiment, the motor to be driven is described as a three-phase brushless motor. However, the present invention can be applied to any motor having a drive coil and an oil-impregnated bearing. . As described above, the present invention has been described with reference to the embodiments. However, the present invention can be variously modified in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.

[0028]

As described above, according to the present invention, when the motor is started in a low-temperature environment, an electric heating current is applied to the drive coil to heat the lubricating oil of the oil-impregnated bearing, thereby reducing the viscosity. It can be started and can reach a predetermined rotational speed in a short time.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an operation of a control circuit in the motor drive device according to the first embodiment.

FIG. 3 is a flowchart illustrating an operation of a control circuit in the motor drive device according to the second embodiment.

FIG. 4 is an operation principle diagram of an inner rotor type brushless motor of a three-phase half-wave conduction type.

FIG. 5 is a diagram illustrating a waveform of a current flowing through a driving coil of each phase with respect to a rotation angle of a rotor.

FIG. 6 is a sectional view showing a structure of an outer rotor type brushless motor.

FIG. 7 is a graph showing temperature characteristics of viscosity of lubricating oil of an oil-impregnated bearing.

[Explanation of symbols]

 1, bracket 2, stator core 3, drive coil 4, rotor 5, rotary shaft 6, thrust plate 7, oil-impregnated bearing 8, magnet 9, retaining plate 10, printed circuit board 11, three Phase brushless motor 12. Brushless motor drive IC 13. Power supply circuit for heat generation 14. Changeover switch 15. Temperature sensor 16. Control circuit 17. Operation unit 18. Power switch

Claims (1)

[Claims] 1. A motor including an oil-impregnated bearing and a coil, a motor driving device including a coil driving unit for controlling a driving current of the coil, a temperature detecting means for detecting a temperature near the motor, And heating control means for supplying heat to the oil-impregnated bearing, and switching control means for switching the connection to the coil from the coil driving section to the heating means based on the detection result of the temperature detecting means. Characteristic motor drive device.