JPH0641378U - Motor rotation speed switching device - Google Patents

Abstract

(57) [Summary] [Object] A motor rotation speed switching device is intended to improve the efficiency of the motor and suppress a decrease in the rotation speed of the motor. A first mode for rotating the motor 1 by selecting a low speed brush 19a and a common brush 19c slidingly contacting the commutator 15 of the motor 1, or a high speed brush 19b slidingly contacting the commutator 15 of the motor 1 and A common brush 19c is selected to include a mode changeover switch 2 for changing over to a second mode in which the motor 1 is rotated at a higher speed than the first mode, and for high speed operation based on heat generation of the motor 1 or an increase in current of the motor 1. A changeover switch 22 having a movable piece 25 whose connection state is switched from the brush 19b to the low speed brush 19a is provided between the high speed brush 19b and the mode changeover switch 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a motor rotation speed switching device.

[0002]

[Prior art]

 Conventionally, in a ferrite magnet type motor, when a mode changeover switch is set to a low speed mode, a common brush and a low speed brush which are in sliding contact with a commutator provided inside the motor are selected. Therefore, the motor rotates at a low rotation speed. When the mode selector switch is set to the high speed mode, the shared brush and the high speed brush provided inside the motor are selected. Therefore, the motor rotates at a higher rotation speed than the above.

By the way, when a high load is applied to the motor, a load current flows in the winding of the motor, and the motor self-heats, which increases winding resistance and reduces the amount of magnetic flux of the magnet. . Therefore, the torque when the motor is restrained and the motor rotation speed when the load is high are reduced. Therefore, in high-load operation, the motor rotation speed falls below the rotation speed in the low-speed mode, despite the high-speed mode being set by the changeover switch.

Further, since the changeover switch selects the high speed mode, the motor current in the high speed mode becomes larger than the motor current in the low speed mode.

[0005]

[Problems to be solved by the device]

 In order to cope with such a high load, there is a problem that the operator has to determine whether or not the high load operation is performed in the high speed mode and to switch to the low speed mode by operating the changeover switch to operate.

The present invention has been made to solve the above problems, and its purpose is to improve the efficiency of the motor and to automatically determine the high load operating state of the motor and switch the rotation speed thereof. The object of the present invention is to provide a rotation speed switching device for a motor.

[0007]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention selects a first brush and a common brush that are in sliding contact with a commutator of a motor to rotate the motor in a first mode or a second brush that is in sliding contact with a commutator of the motor. A motor rotation speed switching device having a mode switching means for switching the motor to a second mode in which the motor is rotated at a higher speed than the first mode by selecting the common brush and the shared brush. A changeover switch having a changeover piece for changing over the connection state from the second brush to the first brush on the basis of heat generation of the motor or an increase in current of the motor is provided between the second brush and the mode switching means. The point is that it is provided between them.

[0008]

[Action]

 When the first mode is selected by the mode switching means, the first brush and the common brush are selected and the motor rotates. The switching piece of the switching switch is connected to the second brush when the motor is not generating heat or when the motor current is not increasing. Therefore, when the second mode is selected by the mode switching means, the second brush and the shared brush are selected, and the motor rotates faster than in the first mode.

At this time, if the motor is in a high load state, that is, if the motor heats up or the motor current increases, the changeover piece of the changeover switch causes the second brush to change to the first brush based on the heat generation of the motor or the increase of the motor current. Automatically switch to 1 brush. For this reason, the motor rotates in the first mode with a low rotation speed even when the second mode is selected, so that the torque increases and the motor can be efficiently driven even in a high load state.

Further, when the motor is stopped and the motor is cooled, the switching piece is automatically connected to the second brush.

[0011]

【Example】

 An embodiment in which the present invention is embodied as a motor rotation speed switching device for operating a wiper for a vehicle will be described with reference to FIGS.

As shown in FIG. 1, the motor 1 is provided with a mode changeover switch 2. The switching piece 2a of the mode selector switch 2 connects the first contact 3a and the earth side contact E when the stop mode is OFF, and connects the first contact 3a and the power supply side when the first mode (low speed mode) is "LOW". The connection with the contact B and the connection between the second contact 3b and the contact B on the power supply side can be selectively switched in the second mode (high speed mode) "HIGH".

Then, the mode switch 2 is set to “LOW”. That is, when the first contact 3a and the power source side contact B are connected by the switching piece 2a, the low speed mode in which the rotation speed of the motor 1 becomes low is set. Also, the mode changeover switch 2 is set to "HIGH". That is, when the second contact 3b and the power supply side contact B are connected by the switching piece 2a, the rotation speed of the motor 1 (the rotation speed of the motor 1 in the low speed mode) is set to the high speed mode. .

A deceleration mechanism (not shown) is integrated with the motor 1, and when the motor 1 rotates, the crank arm 5 of the deceleration mechanism rotates. A connecting rod 6 is connected to the crank arm 5, and the connecting rod 6 swings by the rotation of the crank arm 5. The rod 6 is connected to a pair of wipers 7a and 7b.

Therefore, the rotation of the motor 1 causes the crank arm 5 of the speed reduction mechanism to rotate and the connecting rod 6 to swing. The swinging movement of the connecting rod 6 causes the wipers 7a and 7b to reciprocate to wipe glass (not shown).

As shown in FIG. 2, the case 8 of the motor 1 is composed of a yoke 8a and a gear housing 8b accommodating a speed reducer on the opening side thereof. A storage recess 9 is provided at the base end of the yoke 8a, and an oil-impregnated bearing 10 is disposed in the storage recess 9 inside the yoke 8a. An insertion hole 11 is formed in the gear housing 8b, and an oil-impregnated bearing 12 is arranged in the insertion hole 11. A rotary shaft 13 is rotatably supported by the oil-impregnated bearings 10 and 12. Further, the rotary shaft 13 transmits rotation to the crank arm 5 via a reduction mechanism.

An armature 14 is provided on the rotating shaft 13 in the case 8, and a commutator 15 is provided on one side of the armature 14. A magnet 16 is fixed to the inner peripheral surface of the yoke 8a in the case 8 so as to face the armature 14. A circular support plate 17 orthogonal to the axis of the case 8 is arranged in the gear housing 8b. A through hole 17a is formed in the center of the support plate 17, and the rotary shaft 13 is inserted therethrough.

As shown in FIGS. 2 and 3, first to third brush holders 18 a to 18 c are provided on one side portion (see FIG. 2) of the support plate 17. In addition, a low speed brush 19a is slidably provided in the first brush holder 18a via a spring 20. The low speed brush 19a is brought into sliding contact with the commutator 15 by the biasing force of the spring 20. A high-speed brush 19b is slidably provided in the second brush holder 18b via a spring 20. The high-speed brush 19b is brought into sliding contact with the commutator 15 by the biasing force of the spring 20. Further, a shared brush 19c is slidably provided in the third brush holder 18c via a spring 20. The common brush 19c slides on the commutator 15 by the urging force of the spring 20.

A pair of elastic sandwiching pieces 21 are provided on the support plate 17 adjacent to the second brush holder 18b, and a changeover switch 22 is detachably supported and fixed between the pair of sandwiching pieces 21. Has been done. Further, the changeover switch 22 is arranged in the case 8 particularly near the high speed brush 19b so as to easily detect the heat generation of the motor 1 itself.

As shown in FIG. 4, the housing 23 of the changeover switch 22 is made of aluminum having high heat conductivity. Contacts 24a and 24b are provided in the housing 23. A movable piece 25 made of bimetal is provided in the housing 23. The normally movable piece 25 is connected to the contact 24a. Further, when heat is applied to the movable piece 25, the heat bends the movable piece 25 to connect the contact 24a to the contact 24b. Further, when the movable piece 25 is cooled, the movable piece 25 is connected to the contact 24a by self-recovery.

As shown in FIG. 1, the shared brush 19c that is in sliding contact with the commutator 15 is connected to the earth. The low speed brush 19a slidingly contacting the commutator 15 is connected to the first contact 3a of the mode changeover switch 2 and the contact 24b of the changeover switch 22, respectively. The high-speed brush 19b slidingly contacting the commutator 15 is normally connected to the contact 24a of the changeover switch 22. Further, the movable piece 25 of the changeover switch 22 is connected to the second contact 3b of the mode changeover switch 2.

When the first contact 3a and the power source side contact B are connected by the changeover piece 2a of the mode changeover switch 2, the low speed mode is set and the low speed brush 19a and the common brush 19c are selected. . Therefore, the rotation speed of the motor 1 is low.

On the other hand, in a normal temperature state in which the motor 1 does not generate heat, the movable piece 25 of the changeover switch 22 is connected to the contact 24a. Therefore, when the second contact 3b and the power source side contact B are connected by the switching piece 2a of the mode switching switch 2, the high speed mode is set, and the high speed brush 19b and the common brush 19c are selected. . Therefore, the rotation speed of the motor 1 is high.

In the high temperature state where the motor 1 generates heat, the changeover switch 22 receives the generated heat, the movable piece 25 is bent by the heat, and is connected to the contact 24b. In this case, the low speed brush 19a and the common brush 19c are selected even if the high speed mode is set by the mode selector switch 2. Therefore, the motor 1 enters the low speed mode, the rotation speed becomes low, and the motor current also decreases.

When the heat generation of the motor 1 is suppressed, the temperature of the movable piece 25 of the changeover switch 22 is also lowered by the heat received, and the movable piece 25 itself is deformed so that the movable piece 25 is connected to the contact 24a. It has become. Then, the high speed brush 19b and the common brush 19c are selected again. Therefore, the rotation speed of the motor 1 becomes high again.

Next, various characteristics of the motor 1 will be described. The rotation speeds NH1 and NL1 of the motor 1 with respect to the load torque T in the high speed mode and the low speed mode at room temperature are shown by solid lines in FIG. In the high speed mode and the low speed mode, the rotation speeds NH1 and NL1 of the motor 1 decrease proportionally as the load torque T increases. Further, in the high speed mode, the decreasing inclination is larger than in the low speed mode.

When the motor 1 is heated to a high temperature, the rotational speeds NH2 and NL2 of the motor 1 change with the increase of the load torque T in the high speed mode and the low speed mode, respectively, as shown by the chain double-dashed line. In addition, even in the high temperature state, the decreasing gradient is larger in the high speed mode than in the low speed mode. This characteristic represents a saturated state in which the slopes of the rotation speeds NH2 and NL2 with respect to the load torque T do not change even if the motor 1 further generates heat. The load torque obtained by intersecting the high speed mode rotation speed NH2 and the low speed mode rotation speed NL2, which are in a high temperature state, is defined as T0.

Further, the motor currents IH and IL increase in proportion to the increase of the load torque T when the high speed mode and the low speed mode of the motor 1 are set. The motor current IH in the high speed mode is larger than the motor current IL in the low speed mode, and the increasing gradient is large. The motor currents IH and IL are motor characteristics when the motor 1 heats up.

Next, the operation of the motor rotation speed switching device configured as described above will be described. If the switching piece 2a of the mode changeover switch 2 is connected to the first contact 3a and the contact B on the power source side to set the low speed mode in a normal temperature state where the motor 1 does not generate heat, the low speed brush 19a in the motor 1 is And the shared brush 19c is selected. Therefore, the rotation speed of the motor 1 is set to a low state. Therefore, the crank arm 5 rotates at a low speed based on the rotation speed of the motor 1 to swing the connecting rod 6. By the swinging motion of the connecting rod 6, the pair of wipers 7a and 7b performs a low-speed wiping motion of glass (not shown).

When the changeover piece 2a of the mode changeover switch 2 is connected to the second contact 3b and the power source side contact B to set the high speed mode, the movable piece 25 of the changeover switch 22 provided in the motor 1 is set. Is connected to the first contact 24a, the high speed brush 19b and the common brush 19c are selected. Therefore, the rotation speed of the motor 1 is set to a high state. Therefore, the crank arm 5 rotates at a high speed based on the rotation speed of the motor 1 to swing the connecting rod 6. By the swinging operation of the connecting rod 6, the pair of wipers 7a and 7b perform a high-speed wiping operation of glass (not shown).

Here, in a state where the switching piece 2a of the mode switching switch 2 is set to the high speed mode, a heavy load is applied to the wipers 7a and 7b due to the weight of snow or the like, and the load torque T of the motor 1 is T0. From T1 to T1.

Then, as shown in FIG. 6, the motor current flowing through the motor 1 becomes Ia, and the rotation speed NA of the motor 1 becomes Na. Therefore, it becomes lower than the rotation speed Nb of the motor 1 in the low speed mode.

However, as the motor current increases to Ia, the motor 1 generates heat, so that the temperature inside the case 8 rises. The changeover switch 22 detects this temperature rise. Then, the movable piece 25 in the housing 23 of the changeover switch 22 is flexed by its heat generation and is connected from the contact 24a to the contact 24b. Therefore, even if the high speed mode is set by the mode switch 2, the low speed brush 19a and the common brush 19c are selected, and the rotation speed of the motor 1 is set to a low speed.

Therefore, as shown in FIG. 6, the rotation speed of the motor 1 shifts from Na to Nb, and the motor current shifts from Ia to Ib. That is, the rotation speed increases from Na to Nb, and the motor current decreases from Ia to Ib.

As a result, the decrease in the rotation speed of the motor 1 can be reduced. Since the motor current can be reduced, heat generation of the motor 1 can be suppressed, and the motor 1 can be driven with high efficiency even in the high load state even when the high speed mode is selected.

When the heat generation of the motor 1 is suppressed and the changeover switch 22 is cooled, the movable piece 25 is connected to the contact 24a by the self-recovery of the movable piece 25 in the changeover switch 22 by the cooling. Therefore, the high speed brush 19b and the common brush 19c are selected again. Therefore, the rotation speed of the motor 1 is set to a high speed again.

As a result, when the motor 1 is set in the high speed mode, the load torque T increases, and when the motor 1 heats up, the changeover switch 22 changes over to select the low speed brush 19a and the common brush 19c. As a result, it is possible to suppress a decrease in the rotation speed of the motor 1 and suppress heat generation of the motor 1.

Further, since the changeover switch 22 is located in the vicinity of the high-speed brush 19b, which is a heat generating point in the case 8, the changeover operation can be performed more reliably. In the present embodiment, the changeover switch 22 that senses temperature and performs a changeover operation is used, but a changeover switch having a bimetal that switches from the high speed brush 19b to the low speed brush 19a based on an increase in motor current is used. It is also possible to do so.

Further, it is also possible to use a changeover switch provided with a bimetal that switches from the high speed brush 19b to the low speed brush 19a by a heater heated according to an increase in motor current.

In the present embodiment, the automatic switching device for the motor 1 for wiping the wipers 7a, 7b is embodied, but if the motor 1 has a low speed and a high speed, the rotation speeds of the motor 1 are different from each other. It is also possible to apply the above automatic switching device.

[0041]

[Effect of device]

 As described above in detail, according to the present invention, there is an excellent effect that the efficiency of the motor can be improved and the decrease in the rotation speed of the motor can be suppressed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram for explaining a rotation speed switching device according to the present invention applied to a wiper device.

FIG. 2 is a sectional view of a motor according to the present invention.

FIG. 3 is a partial perspective view showing each brush slidingly contacting a commutator of a motor.

FIG. 4 is a cross-sectional view showing an internal structure of a changeover switch.

FIG. 5 is a characteristic diagram showing various characteristics of the motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Mode selection switch as mode switching means, 15 ... Commutator, 19a ... Low speed brush as 1st brush, 19b ... High speed brush as 2nd brush, 19c ... Shared brush, 22 ... Changeover switch, 25 ... Movable piece as changeover piece

Claims (1)

[Scope of utility model registration request] 1. A first mode for rotating a motor by selecting a first brush and a common brush that slidably contact a commutator of a motor, or a second brush and a common brush that slidably contact a commutator of the motor. A motor rotation speed switching device comprising a mode switching means for selecting and switching to a second mode in which the motor is rotated at a higher speed than the first mode, wherein the motor heat generation or the motor current increase is performed. The rotation of the motor is characterized in that a changeover switch having a changeover piece for switching the connection state from the second brush to the first brush is provided between the second brush and the mode changing means. Speed switching device.