JP5592686B2 - motor - Google Patents

Description

  The present invention relates to a motor provided with a circuit breaker.

  Conventionally, a motor is provided in a brush holder and electrically connected between a brush and a ground. When the temperature rises to a first set temperature (for example, 170 degrees) due to overcurrent, the motor is turned off and is lower than the first set temperature. Some have circuit breakers that are turned on when the temperature falls to a second set temperature (for example, 130 degrees) (see, for example, Patent Document 1).

  In such a motor, for example, when the motor is locked due to an overload or the like, an overcurrent occurs and the circuit breaker temperature rises. When the temperature rises to the first set temperature, the circuit breaker is turned off and the circuit is shut off. Therefore, the overcurrent state is prevented from continuing for a long time. After that, the circuit breaker is cooled by dissipating heat from the ground side heat dissipating component connected via the earth terminal, and when the temperature falls to a second set temperature lower than the first set temperature, the circuit breaker is turned on. Will be restored.

Japanese Patent Laid-Open No. 2005-6434

  By the way, in the motor as described above, if the motor remains locked when the circuit is restored, the above operation (shut-off and return) is repeated. For example, in the case of a motor for a wiper device, especially when the motor is locked by snow or the like in a cold region, the time for the circuit breaker to fall from the first set temperature to the second set temperature is shortened, and the circuit is It may return early. Then, there is a problem that the armature temperature rises due to an increase in the duty ratio of the current waveform (the ratio of the time during which the motor is overcurrent) when the motor is locked. This causes damage to the motor such as burnout of the insulating film based on the temperature rise of the armature and the brush.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a motor that can suppress an increase in temperature of an armature or a brush.

According to the first aspect of the present invention, a brush holder for holding a brush for supplying a drive current to the armature, and a brush holder that is electrically connected between the brush and the ground, and is heated by overcurrent. electrical There a circuit breaker which is turned when lowered to the second set temperature lower than the rising When turned off the first set temperature to a first set temperature, is provided in the brush holder, and said circuit breaker and ground An earth terminal for connection to the circuit breaker, and the circuit breaker is cut off by the circuit breaker based on overcurrent. The earth terminal includes the second terminal from the first set temperature of the circuit breaker. in order to lengthen the time to descend to a set temperature, the circuit breaker and the ground side of the heat radiating portion And summarized in that suppress suppressing portion thermal conduction is provided between the.

  According to this configuration, for example, when the motor is locked due to overload or the like, an overcurrent occurs and the temperature of the circuit breaker rises. When the temperature rises to the first set temperature, the circuit breaker is turned off and the circuit is shut off. Therefore, the overcurrent state is prevented from continuing for a long time. After that, the circuit breaker is cooled by radiating heat from the ground side heat radiating component connected via the earth terminal, and is turned on when the temperature falls to the second set temperature lower than the first set temperature. The circuit is restored. At this time, if the motor remains locked, the above operation is repeated.

Then, the ground terminal, for suppressing suppressing unit heat conduction is provided between the circuit breaker and the ground-side radiating component, extends the time that the circuit breaker is lowered from the first set temperature to a second set temperature It is possible to reduce the duty ratio of the current waveform when the motor is locked (the ratio of the overcurrent time). Therefore, it is possible to suppress an increase in the temperature of the armature or the brush that occurs when the duty ratio (the ratio of the time during which an overcurrent occurs) increases. That is, when the time required for the circuit breaker to fall from the first set temperature to the second set temperature is short without the suppression unit, the duty ratio of the current waveform when the motor is locked (overcurrent) An increase in the time ratio) causes an increase in the temperature of the armature or brush, but this can be avoided. As a result, it is possible to avoid damage to the motor due to the temperature rise of the armature and the brush.

According to a second aspect of the present invention, the gist of the motor of the first aspect is that the suppressing portion is a detour portion having a detour shape.
According to this configuration, since the suppression unit is a detour unit having a detour shape, the effect of the invention of claim 1 can be specifically obtained with a simple configuration.

  According to a third aspect of the present invention, in the motor according to the second aspect, the detour portion is detoured in a width direction orthogonal to the plate thickness direction of the earth terminal and then returns after deviating from the shortest path beyond the width. The gist is that the shape is made.

  According to the same configuration, the detour portion has a detour shape in the width direction orthogonal to the plate thickness direction of the earth terminal, and then returns after deviating from the shortest path more than the width. The heat conduction with the component can be suppressed sufficiently effectively, and can be easily formed at the same time when the earth terminal is punched from the plate material.

According to a fourth aspect of the present invention, in the motor according to the third aspect, the bypass portion is arranged such that the width direction is along the radial direction of the armature.
According to the same configuration, since the detour portion is arranged so that the width direction is along the radial direction of the armature, for example, the abrasion powder of the brush scattered from the armature side shorts the detour portion and It is prevented that the effect which suppresses heat conduction is inhibited. In other words, for example, if the plate thickness direction of the detour part is arranged along the radial direction of the armature, it is easy to receive the abrasion powder of the brush scattered from the armature side, and the wear powder of the brush is detoured. However, this may prevent the effect of suppressing the heat conduction, but this can be prevented.

  According to a fifth aspect of the present invention, in the motor according to the second aspect, the detour portion has a detoured shape in the plate thickness direction of the ground terminal and returns after deviating from the shortest path more than the plate thickness. This is the summary.

  According to this configuration, the detour portion has a detour shape in the plate thickness direction of the earth terminal and returns after deviating from the shortest path more than the plate thickness. A dimensional error of the terminal can be absorbed, and the terminal can be easily and satisfactorily connected according to the connection position with the terminal of the circuit breaker.

  ADVANTAGE OF THE INVENTION According to this invention, the motor which can suppress the temperature rise of an armature or a brush can be provided.

FIG. 2 is a partial cross-sectional view of a motor in the present embodiment. The perspective view of the brush holder in this Embodiment. The top view of the brush holder in this Embodiment. The partial exploded perspective view of the brush holder in this Embodiment. The perspective view of the detour part in another example.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, the motor 1 is used as a drive source of a vehicle wiper device that wipes raindrops and the like adhering to a windshield of the vehicle. The motor 1 includes a motor main body 2 and a speed reduction unit 3.

  The yoke housing 4 of the motor body 2 is made of a conductive metal material and has a substantially bottomed cylindrical shape. Two pairs (a total of four) of magnets 5 are fixed to the inner peripheral surface of the yoke housing 4, and an armature (rotor) 6 is rotatably accommodated inside each magnet 5. A bearing 8 is provided at the bottom of the yoke housing 4 to rotatably support the base end of the rotating shaft 7 of the armature 6. A gear housing 10 of the speed reduction unit 3 is assembled to the opening 4 a of the yoke housing 4 so as to cover the tip end side of the protruding rotating shaft 7.

  The gear housing 10 is made of a conductive metal material such as an aluminum alloy, and has an opening 10 a that has substantially the same shape as the opening 4 a of the yoke housing 4. And the gear housing 10 is formed in the shape which can accommodate the front end side of the rotating shaft 7, the worm wheel which is not shown in figure, etc. In the gear housing 10, a bearing 11 that rotatably supports the central portion of the rotating shaft 7 is provided, and a bearing (not shown) that rotatably supports the tip portion of the rotating shaft 7 is provided. A worm (not shown) is formed on the rotary shaft 7 on the tip side of the bearing 11, and the worm is meshed with a worm wheel. An output shaft (not shown) is provided at the shaft center of the worm wheel, and the speed reduction unit 3 can reduce the rotation of the rotary shaft 7 and output it. The gear housing 10 is attached to the vehicle body via a mounting bracket (not shown) made of a conductive metal material and is electrically grounded. Then, the wiper arm is drivingly connected to the output shaft through the link mechanism of the vehicle wiper device, and the wiper arm performs a predetermined wiping operation by rotating the output shaft.

  A brush holder 21 (see FIGS. 2 to 4) that constitutes a part of the motor body 2 is assembled in the opening 10 a of the gear housing 10. The brush holder 21 includes a holder base 22 made of an insulating material and having a substantially annular shape. The holder base 22 (brush holder 21) is arranged so that the rotating shaft 7 and the commutator 6a fixed to the rotating shaft 7 are inserted through the center portion thereof.

  The holder base 22 includes two choke coils 31 and 32 for noise prevention, three brush support terminals 33 to 35, three brush holder members 36 to 38, a low-speed brush 39 on the positive electrode side, and a high-speed one. , A common brush 41 on the negative electrode side used together with the low-speed and high-speed brushes 39, 40, three torsion coil springs 42 to 44, a ground terminal 45, and a circuit breaker 46 are assembled. Attached.

  The choke coils 31 and 32 are, for example, coils wound around rod-shaped ferrite magnetic cores 31 a and 32 a, and are respectively accommodated in the accommodating portions 22 a erected on the holder base 22. Are respectively connected to an external connector (its positive terminal) of an external power source (not shown) connected to the connector portion 10b (see FIG. 1).

  The brush support terminals 33 to 35 and the earth terminal 45 are formed by bending from a conductive metal plate material by a press device or the like. The brush support terminal 33 corresponding to the low-speed brush 39 is connected to the upper end portion of one choke coil 31 and extends to a position corresponding to the low-speed brush 39 so that the brush support portion 33a is the holder base 22. It is laid on the top surface of. The brush support terminal 34 corresponding to the high-speed brush 40 is connected to the upper end of the other choke coil 32 and extends to a position corresponding to the high-speed brush 40 so that the brush support 34 a is the holder base 22. It is laid on the top surface of. The brush support terminal 35 corresponding to the common brush 41 on the negative electrode side extends from a position corresponding to the breaker holding portion 22b of the holder base 22 to a position corresponding to the common brush 41 on the negative electrode side, and the brush support portion 35a is the holder base. 22 is laid on the upper surface. The brush support portion 33a at a position corresponding to the low-speed brush 39 is in contrast to the brush support portion 35a at a position corresponding to the common brush 41 on the negative electrode side which is mechanically separated from the choke coils 31 and 32 by approximately 180 °. Thus, it is provided at a position mechanically separated by 90 ° in the rotation direction (clockwise direction in FIG. 3). The brush support portion 34a at a position corresponding to the high-speed brush 40 is located at a position corresponding to the low-speed brush 39 with respect to the brush support portion 35a at a position corresponding to the common brush 41 on the negative electrode side. On the opposite side of the support portion 33a, it is provided at a position mechanically spaced apart by an angle greater than 90 ° in the counter-rotating direction (counterclockwise direction in FIG. 3).

  The brush holder members 36 to 38 are punched from a conductive metal plate by a press device or the like and are bent, and are composed of a pair of parallel side walls and an upper wall connecting their upper ends. And the brush holder members 36-38 are being fixed because the fixing piece extended from the lower end of a side wall penetrates the said brush support parts 33a-35a and the holder base 22, and is crimped. And each brush 39-41 is accommodated and hold | maintained so that a movement to a radial direction is possible inside the substantially square cylinder shape formed with the brush support parts 33a-35a and the brush holder members 36-38. The brushes 39 to 41 are electrically and reliably connected to the brush support portions 33a to 35a via the pigtails 39a to 41a, respectively. Further, the brushes 39 to 41 are urged radially inward (commutator 6a side) by torsion coil springs 42 to 44 that are externally fitted and supported by spring support columns 22c erected on the holder base 22. .

  The ground terminal 45 is arranged to extend from a position corresponding to the breaker holding portion 22b of the holder base 22 to a position corresponding to the mounting portion 22d (see FIG. 3) of the holder base 22.

  Specifically, first, as shown in FIG. 2, the breaker holding portion 22b of the present embodiment is provided between the negative-side common brush 41 and the high-speed brush 40 in the holder base 22, and is common to the negative-side. It is formed so as to bulge upward in the shape of a bottomed square cylinder that is open near the brush 41. The circuit breaker 46 is inserted and held in the breaker holding portion 22b from below. Further, in this state, the first and second terminals 46a, 46b of the circuit breaker 46 are disposed so as to protrude upward through the bottom portion (surface covering the upper side) of the breaker holding portion 22b. Further, the terminal 35b of the brush support terminal 35 is electrically connected to the first terminal 46a. Further, the circuit breaker 46 accommodates a bimetal switch therein, and when the temperature rises to a first set temperature (for example, 170 degrees) due to an overcurrent, the circuit breaker 46 is turned off to shut off the circuit, and the first set temperature. When it falls to a lower second set temperature (for example, 130 degrees), it returns to the on state.

  Further, as shown in FIG. 3, the mounting portion 22d is between the common brush 41 on the negative electrode side of the holder base 22 and the high-speed brush 40, and is up and down (front and back) near the high-speed brush 40. It is formed in a shape that penetrates and is radially open. A cylindrical rubber bush 47 penetrating in the vertical direction is fitted to the mounting portion 22d from the outside in the radial direction. As shown in FIG. 3, a similar attachment portion 22e is formed between the common brush 41 on the negative electrode side of the holder base 22 and the low-speed brush 39, and a similar rubber bush 48 is fitted. Has been.

  As shown in FIGS. 2 and 4, the earth terminal 45 includes a breaker side terminal 45 a connected to the second terminal 46 b of the circuit breaker 46, and a ground side terminal 45 b in surface contact with the upper surface of the rubber bush 47. And a detour part 45c as a suppressing part for connecting the breaker side terminal 45a and the ground side terminal 45b. The detour portion 45c has a shape detoured so as to suppress heat conduction between the circuit breaker 46 (breaker side terminal 45a) and the heat radiation component (gear housing 10 in the present embodiment) on the ground side (ground side terminal 45b). It is said that. The detoured shape is a shape that does not include a shape that is bent only once in order to avoid an obstacle, and is a shape that once deviates from the route at the shortest distance. Specifically, the detour circuit portion 45c of the present embodiment includes a breaker holding portion 22b whose width direction (direction parallel to the plate surface) perpendicular to the plate thickness direction of the ground terminal 45 extends along the radial direction of the armature 6. It is arranged along the side wall. And the detour part 45c is made into the detour shape which returns after it remove | deviates from the shortest path | route (path | route extended up and down) more than the width | variety in the said width direction. More specifically, the detour portion 45c includes a first path 45d extending downward from above on the breaker side terminal 45a side, and a second path extending radially inward from the tip of the first path 45d beyond the width along the radial direction of the first path 45d. 45e, a third path 45f extending downward from the tip, a fourth path 45g extending radially outward from the tip, and a fifth path 45h extending downward from the tip.

  The holder base 22 (brush holder 21) passes through the mounting portions 22d and 22e and the rubber bushes 47 and 48, and is screwed into a female screw 10c (only one is shown in FIG. 1) of the gear housing 10. 50 is fixed to the gear housing 10. At this time, the ground side terminal 45b of the earth terminal 45 is fastened by the head of the screw 49, and is connected to the gear housing 10 as a heat radiation component connected to the ground (is pressed and electrically connected). It will be.

  In the motor 1, for example, a drive current is supplied from an external power source to the commutator 6 a (winding of the armature 6) via the choke coil 31, the brush support terminal 33, and the low-speed brush 39. 41, the brush support terminal 35, the circuit breaker 46, the ground terminal 45, and the gear housing 10 in this order.

Next, characteristic effects of the above embodiment will be described below.
(1) For example, when the rotation of the motor 1 is locked due to an overload on the wiper arm due to snow or the like particularly in a cold region, an overcurrent is generated and the temperature of the circuit breaker 46 rises, and this temperature is a first set temperature (eg 170 degree), the circuit breaker 46 is turned off and the circuit is shut off. Therefore, the overcurrent state is prevented from continuing for a long time. Thereafter, the circuit breaker 46 is cooled by heat radiation in the gear housing 10 on the ground side connected via the earth terminal 45, and the temperature is cooled to a second set temperature (for example, 130) lower than the first set temperature. ), The circuit is restored. At this time, if the rotation of the motor 1 is still locked, the above operation is repeated.

  The earth terminal 45 is provided with a detour portion 45c for suppressing heat conduction between the circuit breaker 46 and the ground-side gear housing 10, so that the circuit breaker 46 is set from the first set temperature to the second set temperature. The time for the temperature to drop can be lengthened. As a result, the duty ratio of the current waveform in the state where the rotation of the motor 1 is locked (for a long time) (the ratio of the time during which the overcurrent is present) can be reduced. Therefore, it is possible to suppress the temperature rise of the armature 6 and the brushes 39 to 41 that are generated when the duty ratio (the ratio of the time during which an overcurrent occurs) increases. That is, when the circuit breaker 46 does not include the detour portion 45c and the time for the circuit breaker 46 to fall from the first set temperature to the second set temperature is short, the duty ratio (overcurrent) of the current waveform when the motor 1 is locked As the ratio of time becomes larger, the temperature of the armature 6 and the brushes 39 to 41 is increased. This can be avoided. Specifically, in the case of the motor 1 of the present embodiment, when the duty ratio exceeds 30%, the temperature of the armature 6 and the brushes 39 to 41 is increased. As a result of the experiment, the duty ratio is 45% when the detour portion 45c is not provided in a cold region. Therefore, in the present embodiment, since the detour portion 45c is provided so that the duty ratio is 25%, which is 30% or less under cold conditions, the temperature rise of the armature 6 and the brushes 39 to 41 can be avoided. it can. As a result, damage to the motor 1 due to the temperature rise of the armature 6 and the brushes 39 to 41 can be avoided.

  (2) The depressing portion for suppressing heat conduction between the circuit breaker 46 and the ground side gear housing 10 (heat dissipating component) is a detoured detour portion 45c, that is, the circuit breaker 46 is grounded. Since the ground terminal 45 serving as a heat conduction transmission path to the gear housing 10 on the side is positively formed long, the effect described in the above (1) can be specifically obtained with a simple configuration. In addition, as a suppression part for suppressing heat conduction, it is also possible to narrow the part between the circuit breaker 46 of the earth terminal 45 and the gear housing 10 on the ground side to suppress heat conduction. Since the electrical resistance is also greatly increased as compared with the heat conduction suppressing effect, it is preferable to provide a bypass circuit portion 45c having a bypass shape as described above.

  (3) Since the detour portion 45c has a detoured shape in the width direction orthogonal to the plate thickness direction of the ground terminal 45, the circuit breaker 46 and the gear housing 10 Can be sufficiently effectively suppressed (almost without increasing the electrical resistance), and at the same time when the earth terminal 45 is punched from the plate material, it can be easily formed.

  (4) Since the detour portion 45c is arranged so that the width direction is along the radial direction of the armature 6, for example, wear powder of the brushes 39 to 41 scattered from the armature 6 side adheres to the detour portion. It is prevented that the effect which suppresses the said heat conduction is inhibited by short-circuiting 45c. In other words, for example, when the plate thickness direction of the detour portion is arranged along the radial direction of the armature 6, it is easy to receive the wear powder of the brushes 39 to 41 scattered from the armature side, and the wear powder of the brush However, this may prevent the effect of suppressing the heat conduction, but this can be prevented. In particular, as in the present embodiment, when the detour portion 45c has a shape that is removed from the shortest path radially inward and then returned, there is no opening radially inward of the detour portion 45c, and the second path 45e. Since the wear powder of the brushes 39 to 41 does not easily enter between the first path 45g and the fourth path 45g, it is difficult for the detour portion 45c to be short-circuited and the effect of suppressing heat conduction is reduced.

The above embodiment may be modified as follows.
-The detour part 45c of the said embodiment may be changed into another suppression part, if the heat conduction between the circuit breaker 46 and the ground side heat radiating component (gear housing 10) can be suppressed.

  For example, the detour unit 45c of the above embodiment may be changed to a detour unit 51 having a detour shape as shown in FIG. The detour portion 51 has a detour shape in the thickness direction of the ground terminal 45 that deviates from the shortest path more than the thickness of the ground terminal 45 and returns (returns twice and returns twice). In this way, the detour portion 51 has a spring property, and can absorb, for example, a dimensional error of the ground terminal 45, and the terminal (breaker side terminal 45a) is connected to the terminal of the circuit breaker 46 ( An easy and good connection can be made according to the connection position with the second terminal 46b).

  Further, for example, the detour portion 45c of the above embodiment has a shape that returns from the shortest path to the inside in the radial direction, but may have a shape that returns from the shortest path to the outside in the radial direction. It is good also as a shape (it removes twice and returns twice).

  In addition, for example, the detour portion 45c of the above embodiment is arranged so that the width direction orthogonal to the plate thickness direction of the ground terminal 45 is along the radial direction of the armature 6, but is not limited thereto. For example, you may arrange | position so that the plate | board thickness direction of a detour part may follow the radial direction of the armature 6. FIG.

  In the above embodiment, the circuit breaker 46 has a first set temperature of 170 degrees and a second set temperature of 130 degrees, but is not limited to this, and the first and second set temperatures are other than A value circuit breaker may be used.

  In the above embodiment, the motor 1 is provided with the positive-side low-speed brush 39 and the high-speed brush 40, but the positive-side brush may be embodied as one motor. In the above embodiment, the motor 1 is used as a drive source for the vehicle wiper device. However, the present invention is not limited to this, and the motor 1 may be used in another device.

  6 ... armature, 10 ... gear housing (heat dissipating part), 21 ... brush holder, 39-41 ... brush, 45 ... ground terminal, 45c, 51 ... detour part (suppression part), 46 ... circuit breaker.

Claims (5)

A brush holder for holding a brush for supplying a drive current to the armature;
Together provided in the brush holder, said brushes and is electrically connected between the ground and the temperature by the overcurrent is lowered to a second set temperature lower than the rising when the first set temperature turned off until the first set temperature A circuit breaker that is turned on;
Provided in the brush holder, comprising a ground terminal for electrically connecting the circuit breaker and the ground, a motor whose circuit is interrupted by the circuit breaker based on overcurrent,
Wherein the ground terminal, in order to lengthen the time that drops from the first set temperature of the circuit breaker to the second set temperature, suppressing inhibiting thermal conduction between the heat dissipating part of the circuit breaker and the ground-side A motor characterized in that a portion is provided. The motor according to claim 1,
The motor is characterized in that the suppression unit is a bypass unit having a bypass shape. The motor according to claim 2,
The detour part has a detoured shape in a width direction orthogonal to the plate thickness direction of the earth terminal and returns after deviating from the shortest path more than the width. The motor according to claim 3, wherein
The detour unit is arranged so that the width direction is along the radial direction of the armature. The motor according to claim 2,
The detour portion has a detour shape in a plate thickness direction of the earth terminal and returns after deviating from the shortest path more than the plate thickness.

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