JPH0231900Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a DC motor whose speed can be changed by the structure of the motor itself.

For example, a small direct current motor is used as a drive source for a fan for forced air cooling of an automobile radiator, and the motor is turned on and off depending on the temperature of the coolant inside the radiator. Further, for such applications, a motor drive circuit that changes the motor rotation speed based on a plurality of temperature set points may be used from the viewpoint of noise reduction. An example of this will be explained with reference to FIG. Connected in series to battery 1, the radiator coolant temperature is set to the first set temperature (e.g. 80℃)
thermo switch 2 that turns on when the temperature is reached;
A low resistance R5 is inserted in series between the motor 4 that rotationally drives the fan 3 and the thermoswitch 2, and a low resistance R5 is connected in parallel with the resistance 5 to adjust the temperature of the coolant of the radiator to a second set temperature (for example, 90 degrees Celsius). ), the thermoswitch 6 is turned on when the temperature is reached.

In this conventional variable motor speed circuit, when the temperature of the coolant in the radiator reaches 80°C, the thermoswitch 2 is turned on, battery current is applied to the motor 4 via the resistor 5, and the motor 4 rotates at a certain rotation speed. . In this case, the resistor 5 lowers the voltage by a predetermined value to reduce the voltage applied to the motor 4 and suppress the rotational speed. Furthermore, when the temperature of the coolant in the radiator rises, thermoswitch 6 is activated in addition to thermoswitch 2.
is turned on, the resistor 5 is short-circuited, and the battery 1 is directly connected to the motor 4. As a result, the motor 4 rotates at full speed.

However, according to the conventional configuration as shown in FIG. 1, it is necessary to insert a resistor 5 into the circuit to change the speed of the motor 4, and when the motor 4 rotates at low speed, the resistor 5 wastes energy, resulting in energy saving. The drawback was that this was not done.

An object of the present invention is to provide a DC motor whose speed can be changed by the structure of the motor itself.

In the present invention, at least two ring-shaped conductors are arranged on the circumferential surface of a motor shaft at an angle of 180 degrees or less, and these are electrically connected. A switch mechanism with a brush in sliding contact is inserted into the circuit in place of a conventional resistor to obtain low-speed rotation.

FIG. 2 shows an embodiment of the present invention,
A casing 11 that protects and accommodates each member constituting the motor M, bearings 12a and 12b provided on both sides of the casing 11, and a bearing 12.
a shaft 13 pivotally supported by a, 12b;
An armature 14 is rotatably fixed to the shaft 13 and applies a rotational force to the shaft 1 using a current supplied from a battery, and an armature 14 is arranged in parallel with the armature 14 to apply current from the battery to each winding of the armature 14. A commutator 15 has a plurality of conductor pieces arranged with gaps on the circumferential surface of the shaft 13 in order to sequentially supply a plurality of conductor pieces. A brush 16 for transmitting current to the conductor piece and a casing 1 facing the armature 14.
A permanent magnet 17 such as ferrite, which is fixedly installed inside the shaft 13 and applies a predetermined magnetic field to the armature 14; at least two ring-shaped conductors 21 arranged on the circumferential surface of the shaft 13; The switch mechanism 20 includes a pair of brushes that are disposed opposite each other and come into sliding contact with the conductor 21, and has a plurality of electrically interrupted sections during one revolution of the shaft 13.

FIG. 3 shows the details of the switch mechanism 20, which includes a disk-shaped insulator 23 fixed to the shaft 13 with a screw or the like, and a θ _K on the outer periphery of the insulator 23 with a gap of θ _J. A pair of conductors 21 attached at an angle of It is composed of a brush 22. Although the switch mechanism 20 is installed on the opposite side of the commutator 15 with the armature 14 in between in FIG. 2, it can be installed in any desired position.
It may be provided between the commutator 15 or close to the commutator 15. Furthermore, the switch mechanism 20 is not limited to this, and as shown in FIG.
The conductor 21 may be provided all over the outer periphery, and slits 210 may be provided at arbitrary intervals.

In the above configuration, the motor M rotates at full speed by connecting a DC power source of a specified voltage between the brushes 16 with the configuration excluding the switch mechanism 20. Along with this rotation, the conductor 21 fixed to the insulator 23 also rotates and comes into contact with the brush 22. The period during which the conductor 21 and the brush 22 are in contact is turned on,
If the period during which the outer periphery of the insulator 23 and the brush 22 are in contact is considered to be off, the on/off state during one revolution is as shown in FIG. 3, and it can be seen that it exhibits a function similar to that of a switching element. Therefore, if this switch mechanism 20 is connected between the motor circuit and the DC power supply (battery), the commutator current will flow intermittently according to the waveform shown in FIG.
Similar to current control using a thyristor, the rotational speed of the motor M can be reduced by reducing the average current. The rotational speed (speed) of the motor M decreases at a higher rate as the length of the conductor 21 becomes shorter. Moreover, the longer the length of the conductor 21, the smoother the low speed rotation can be obtained.

FIG. 5 shows an example in which an embodiment of the present invention is applied to a radiator cooling motor circuit as shown in FIG. In FIG. 5, the same reference numerals are used for parts that are the same as those shown in FIG. 1, and duplicate explanations are omitted. A normally closed contact 51 driven by a timer 50 is connected in parallel with the thermo switch 6, and a switch mechanism 20 is connected in parallel with the thermo switch 6.
The configuration in which the two are connected differs from that in FIG.

In the above configuration, when the coolant temperature in the radiator exceeds 80° C., the thermoswitch 2 is closed, the timer 50 is energized, and the normally closed contact 51 is closed after a certain period of time. At this time, the thermo switch 6 is off. Therefore, the current to the armature 14 is applied via the switch mechanism 20, and in this case, the current flows in the waveform (energization interval) shown in FIG. 4, and the motor M rotates at a low speed. If the coolant temperature inside the radiator becomes even higher and exceeds 90℃, thermo switch 6 will be activated.
is closed, and the switch mechanism 20 is short-circuited by this switch. Therefore, the brush 16 is supplied with a straight current, and the motor M is operated at full speed rotation. When the temperature of the coolant in the radiator falls below 90°C, the switch mechanism 20 intervenes again to reduce the rotation speed, and when the temperature of the coolant falls below 80°C, the power to the armature 14 is cut off and the motor M stops.

Note that although the above explanation has been given using a radiator cooling motor circuit as an example, the present invention is not limited to this, and can be applied to all applications that require speed changes.

As is clear from the above, according to the present invention, since the speed can be changed by the structure of the motor itself, there is no need to add a series resistor, etc.
Energy savings can be achieved by this amount.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional motor speed variable circuit.
FIG. 2 is a sectional view of an embodiment of the present invention, FIG. 3 is a side sectional view showing details of the switch mechanism 20 according to the present invention, and FIG. 4 is a switching waveform diagram by the switch mechanism 20 shown in FIG. Fig. 5 is a circuit diagram showing an example in which the motor according to the present invention is applied to a radiator cooling motor, and Fig. 6 is a switch mechanism 2 according to the present invention.
0 is a side cross-sectional view showing another example of 0. 3...fan, 11...casing, 12a,
12b...Bearing, 13...Shaft, 14
... Armature, 15 ... Commutator, 16, 22 ... Brush, 20 ... Switch mechanism, 21 ... Conductor, 2
3... Insulator, 24... Jumper wire, M... Motor.

Claims (1)

[Scope of utility model registration request] A DC motor comprising a shaft rotatably supported by a casing, and an armature that rotates the shaft by receiving DC power from the outside via a commutator fixed to the shaft. at least two conductors of a predetermined length arranged at a predetermined interval on the circumferential surface of the conductor and electrically connected to each other, and a brush in sliding contact with the surface of each of a pair of these conductors. 1. A direct current motor comprising: a switch mechanism having a switch mechanism, the switch mechanism being connected in series with the armature when deceleration is requested.