JP5583831B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor.

  Conventionally, in an electric motor with a brush, a current is supplied while the brush is in sliding contact with the rotating rotor. Therefore, in order to prevent the temperature of the brush from rising excessively, temperature detection means such as a thermistor is provided on the brush mount on which the brush is mounted to detect the temperature of the brush.

  Patent Document 1 discloses a thermistor mounting structure in a brushed DC motor. In this brushed DC motor, a through hole for attaching the thermistor is formed in the holding plate, and the thermistor is inserted and held therein to hold the thermistor.

JP-A-11-299177

  In the DC motor with a brush described in Patent Document 1, when the thermistor is attached to the brush mount, the thermistor is inserted and held in the through hole, and at the same time, the lead wire is led out to the back side of the holding plate and connected to the holding plate. However, in the brushed DC motor described in Patent Document 1, there is a possibility that the thermistor may come off or the lead wire may be disconnected when vibration or the like is applied.

  Accordingly, an object of the present invention is to provide an electric motor that can detect the temperature of a brush with a thermistor and can prevent the thermistor from being detached or the lead wire from being disconnected due to vibration or the like.

  The present invention includes a rotor that is rotatable with respect to a brush mount, a plurality of brushes that are fixed to the brush mount so as to be movable back and forth toward the rotor, and that are slidably contacted with the rotor; A brush holder that is slidably supported, and a temperature detecting means that is fixed by an adhesive filled between the brush holders and detects the temperature of the brush. A first adhesive that transmits the temperature to the temperature detecting means, and a second adhesive that is filled in the upper part of the first adhesive and has a higher viscosity than the first adhesive. And

  According to the present invention, the second adhesive having a higher viscosity than the first adhesive is overlaid and filled on the upper part of the first adhesive that transmits the heat of the brush. Thus, by filling the adhesive having two different characteristics, it is possible to detect the temperature of the brush with the thermistor, and to prevent the thermistor from being detached or the lead wire from being disconnected due to vibration or the like.

It is a front view which shows the internal structure of the electric motor which concerns on embodiment of this invention. It is AA sectional drawing in FIG. It is a front view in the state where adhesives were applied to the electric motor of FIG.

  Hereinafter, an electric motor 100 according to an embodiment of the present invention will be described with reference to the drawings.

  First, the configuration of the electric motor 100 will be described with reference to FIGS. 1 to 3. FIGS. 1 and 2 show a state in which the adhesives 40 and 50 are not filled in order to explain the mounting manner of the thermistor 10 in detail.

  The electric motor 100 supports a brush mount 1 fixed inside a casing (not shown), four brushes (not shown) provided so as to be able to advance and retreat toward the inner periphery of the brush mount 1, and the respective brushes. The four brush holders 2, a rotor (not shown) that rotates while being in sliding contact with the four brushes, and a plurality of permanent magnets (not shown) that are provided to face the outer periphery of the rotor and form a magnetic field. .

  The electric motor 100 is a four-pole electric motor including two pairs of brushes having two different polarities on the positive side and the negative side. Of the four brushes, two brushes facing each other have the same polarity.

  The electric motor 100 is controlled by a controller (not shown). The electric motor 100 is configured such that a current supplied from a power supply device (not shown) via a power line 3 is supplied to a rotor via a brush, and a magnet magnetized by the flow of current causes a magnet's attractive force and repulsion to be generated. It operates by rotating inside the permanent magnet by force.

  The brush mount 1 is an annular plate that is fixed inside the electric motor 100 and has a circular center hole 1b through which a rotor shaft is inserted. The brush mount 1 is formed of a resin, but may be an insulating material even if it is not a resin. A brush holder 2 is disposed on the brush mount 1 so as to face the center hole 1b.

  The brush holder 2 slides in a holding groove 2a formed toward the inner periphery of the brush mount 1, and supports a brush that can advance and retreat with respect to the rotor. The holding groove 2a is provided with an urging means (not shown) such as a spring, and urges the brush toward the rotor.

  The brush holder 2 is disposed in a radial pattern around the rotation axis of the rotor at equal intervals in the circumferential direction of the brush mount 1. The brush holder 2 is connected to the power line 3 in a state where the coating is peeled off, and supplies current supplied from the power supply device to the rotor via the brush. The thermistor 10 for detecting the temperature of the brush holder 2 is in contact with and fixed to the brush holder 2.

  The pair of power lines 3 are connected to the brush holders 2 provided adjacent to each other when viewed in FIG. Power is supplied to the lower two brush holders 2 by wiring (not shown) connected to the upper two brush holders 2.

  The thermistor 10 is an element whose resistance value changes according to the detected temperature. A constant voltage is applied to the thermistor 10, and the temperature can be detected by a current value that varies inversely with a change in resistance value. This thermistor 10 corresponds to a temperature detection means.

  The thermistor 10 includes a sensor unit 11 fixed in contact with the brush holder 2 and a pair of lead wires 12 through which a current flows. The thermistor 10 detects the temperature of the brush holder 2 and is attached to at least one brush holder 2 so that the temperature of the brush holder 2 does not increase excessively.

  Here, the temperature of the brush holder 2 is substantially the same as the temperature of the brush. Therefore, by detecting the temperature of the brush holder 2 with the thermistor 10 and preventing the temperature of the brush from rising excessively, failures such as seizure of the electric motor 100 can be prevented.

  The thermistor 10 is laid down so that the lead wire 12 extends along the brush mount 1 from the sensor portion 11 formed with a rounded tip. The pair of lead wires 12 of the thermistor 10 are entangled and fixed to a pair of posts 20 that are fixed by fitting the base ends 23 into the brush mount 1 and are electrically connected.

  The post 20 is provided as a terminal that collects wiring of the thermistor 10 and the resistor 30. The thermistor 10 and the resistor 30 are connected to the post 20 so as to form a parallel circuit. Specifically, one lead wire 12 of the thermistor 10 is connected to one post 20, and the other lead wire 12 is connected to the other post 20. Similarly, one lead wire 31 of the resistor 30 is connected to one post 20, and the other lead wire 31 is connected to the other post 20.

  Each post 20 is electrically connected to a sensor line 21 for supplying a current to the thermistor 10 and detecting the temperature of the brush as a resistance value, and is pulled out to the outside. Therefore, when a voltage is applied from the sensor line 21, the thermistor 10 and the resistor 30 are electrically connected in parallel, and thus the same voltage is applied to the thermistor 10 and the resistor 30. The

  The post 20 is made of a conductive material because current must flow. Since the brush mount 1 is formed of an insulating material, there is no short circuit between the posts 20.

  The post 20 is disposed between the pair of power lines 3 in order to minimize the length of the sensor line 21. That is, the post 20 is disposed between the two brush holders 2 provided adjacent to each other as viewed in FIG. Thereby, it is possible to pull out the sensor line 21 provided between the power lines 3 to the outside of the electric motor 100 at the shortest distance together with the power lines 3 connected to the upper two brush holders 2.

  As shown in FIG. 2, a tip crack 22 is formed at the tip of the post 20. The leading crack 22 is provided to hold the sensor wire 21. The interval between the front cracks 22 is formed to be approximately the same as the diameter of the sensor wire 21.

  The sensor wire 21 is attached so as to be fitted into the cracked portion 22 in a state where the coating is peeled off, and is fixed by soldering. A constant voltage is applied to the sensor line 21, and the magnitude of the resistance is detected by the magnitude of the flowing current.

  A lead wire 31 of a resistor 30 provided in parallel with the thermistor 10 is further tangled and fixed to the post 20 and electrically connected thereto.

  The resistor 30 is a fixed resistor that is provided in parallel with the thermistor 10 and has a specific resistance value. Therefore, the resistance value detected via the sensor line 21 is the resistance value of the combined resistance of the thermistor 10 and the resistor 30.

  The resistor 30 is provided to correct the magnitude of the combined resistance with the thermistor 10 and obtain an output of a current that changes linearly with a change in temperature. That is, the resistor 30 is provided to adjust the output from the thermistor 10. Although the resistance change of the thermistor 10 is not linear with respect to temperature, by providing the resistor 30, the range of the magnitude of the output current is adjusted, and the combined resistance value of the thermistor 10 and the resistor 30 is approximated linearly. It is possible.

  The lead wire 31 of the resistor 30 is entangled in the post 20 above the lead wire 12 of the thermistor 10 and below the sensor wire 21. The resistor 30 is placed on top of a cylindrical protrusion 1c (see FIG. 1), which is a cylindrical protrusion formed on the brush mount 1.

  FIG. 3 shows a state in which the brush mount 1 in FIGS. 1 and 2 is filled with adhesives 40 and 50. The adhesives 40 and 50 are both non-conductive adhesives. The adhesive 40 is provided to fix the thermistor 10 to the brush holder 2 and transmit the temperature of the brush holder 2 to the thermistor 10. The adhesive 50 is provided on top of the adhesive 40 in order to fix and insulate the post 20, the resistor 30, the power line 3 and the sensor line 21.

  The adhesive 40 is an adhesive having a higher thermal conductivity than the adhesive 50. Specifically, the thermal conductivity of the adhesive 40 is, for example, about 1.6 (W / (m · K)). Therefore, the temperature of the brush is transmitted to the brush holder 2, and the temperature of the brush holder 2 is transmitted to the thermistor 10 via the adhesive 40. This adhesive 40 corresponds to the first adhesive.

  When the adhesive 40 is not filled, since the tip of the sensor portion 11 of the thermistor 10 is formed in a rounded shape, the sensor portion 11 and the brush holder 2 are in contact with each other by a line. On the other hand, since the adhesive 40 is filled in the electric motor 100, the sensor unit 11 and the brush holder 2 can be brought into contact with each other through the adhesive 40. Therefore, the thermal conductivity between the sensor unit 11 and the brush holder 2 is improved.

  In order to prevent the adhesive 40 from flowing out, the brush mount 1 is formed with an inner peripheral wall 5 and an outer peripheral wall 6, and is filled with the adhesive 40 so as to be surrounded by the inner peripheral wall 5 and the outer peripheral wall 6. 9 is defined. The inner peripheral wall 5 and the outer peripheral wall 6 correspond to restriction walls for restricting the flow of the adhesive 40.

  The lead wire 12 of the thermistor 10 passes through the filling portion 9. When the filling portion 9 is filled with the adhesive 40 and cured, the lead wire 12 is fixed and insulated. Thereby, even if the impact by vibration etc. acts, the lead wire 12 does not vibrate and it can prevent that the lead wire 12 is disconnected.

  The inner peripheral wall 5 is formed between a pair of adjacent brush holders 2 along the center hole 1b. The inner peripheral wall 5 is formed at substantially the same height as the sensor portion 11 of the thermistor 10.

  The outer peripheral wall 6 surrounds the outer periphery of the post 20 and is formed so as to connect the inner peripheral wall 5 and the cylindrical projection 1c. Thus, the outer peripheral wall 6 and the inner peripheral wall 5 surround the section filled with the adhesive 40. A cutout 7 into which the sensor portion 11 of the thermistor 10 is fitted is formed in the outer peripheral wall 6 facing the one brush holder 2. The outer peripheral wall 6 is formed at substantially the same height as the inner peripheral wall 5.

  The notch 7 is formed so that the sensor portion 11 of the thermistor 10 protrudes toward the brush holder 2. The notch 7 is formed slightly larger than the outer shape of the sensor unit 11. Therefore, a slight gap 8 is formed between the notch 7 and the sensor unit 11. Therefore, the adhesive 40 flows out from the notch 7 to the brush holder 2 and is filled so as to fill between the brush holder 2 and the sensor unit 11.

  The gap 8 is formed in a size that allows the adhesive 40 to flow out to fill the space between the brush holder 2 and the sensor unit 11. If the gap 8 is too large, the adhesive 40 flows out more than necessary, and if the gap 8 is too small, the adhesive 40 does not flow out sufficiently.

  The adhesive 50 is an adhesive having a higher viscosity than the adhesive 40. Specifically, the viscosity of the adhesive 40 is, for example, about 18 (Pa · s), and the viscosity of the adhesive 50 is, for example, about 20 (Pa · s). Since the wall portion corresponding to the inner peripheral wall 5 and the outer peripheral wall 6 for the adhesive 40 is not formed in the section filled with the adhesive 50, the viscosity is such that it can be cured in place without flowing down. is necessary.

  By filling the adhesive 50, the post 20, the resistor 30, the power line 3 and the sensor line 21 are firmly fixed, and can be prevented from falling off due to vibration or the like. This adhesive 50 corresponds to the second adhesive.

  During the operation of the electric motor 100, the brush supported by the brush holder 2 and the rotating rotor are in sliding contact with each other, so that the brush is scraped to generate powder. If this powder adheres to the periphery of the power line 3, there is a possibility of causing a short circuit with the sensor line 21. In the electric motor 100, since the power line 3 and the sensor line 21 are covered with the adhesive 50, it is possible to prevent a short circuit due to adhesion of powder generated by shaving the brush.

  Hereinafter, the operation of the electric motor 100 will be described.

  A current supplied from the power line 3 to the brush holder 2 is supplied to the rotor via the brush. The rotor is magnetized as a current flows, and rotates while being in sliding contact with the brush by an attractive force and a repulsive force acting between the permanent magnet surrounding the outer periphery.

  When the rotor rotates, frictional heat is generated between the brush and the brush in sliding contact. The thermistor 10 is provided so that the sensor unit 11 is in contact with the brush holder 2, and is bonded so as to be in surface contact with an adhesive 40. Since the adhesive 40 is an adhesive having a high thermal conductivity, the temperature of the sensor unit 11 is substantially the same as the temperature of the brush holder 2. Since the brush holder 2 and the brush are slidably in contact with each other, their temperatures are substantially the same. Therefore, the thermistor 10 can detect the temperature of the brush.

  A constant voltage is applied to the thermistor 10 whose resistance value changes with temperature, and the temperature can be detected by a current value that changes inversely with the change in resistance value. Therefore, it is possible to monitor the temperature of the brush holder 2 detected by the sensor unit 11 by a change in the current value input to the controller.

  Here, a pair of posts 20 as terminals for fixing the thermistor 10, the resistor 30, and the sensor wire 21 are fixed by fitting the base end 23 into the brush mount 1.

  When assembling the electric motor 100, the lead wire 12 of the thermistor 10 is entangled with the post 20, the lead wire 31 of the resistor 30 is entangled with the upper portion, and the sensor wire 21 is fitted into the cracked portion 22 with the upper portion thereof. Secure and solder. In the electric motor 100, the lead wire 12 and the lead wire 31 are fixed by being entangled with the post, and the sensor wire 21 is fixed by being fitted into the cracked portion 22. Therefore, the lead wires 12 and 31 and the sensor wire 21 may be fixed to the post 20, and assembly is easy.

  Next, the adhesive 40 is filled and the thermistor 10 is fixed. Since the adhesive 40 has a lower viscosity than the adhesive 50, the adhesive 40 flows out from a slight gap between the sensor unit 11 and the notch 7, and is hardened by filling between the sensor unit 11 and the brush holder 2. Since the adhesive 40 has a high thermal conductivity, the heat of the brush holder 2 is transmitted to the sensor unit 11, and the sensor unit 11 can detect the temperature of the brush holder 2.

  At this time, the inner peripheral wall 5 and the outer peripheral wall 6 are defined in the brush mount 1, and the filling portion 9 is defined by being surrounded by the inner peripheral wall 5 and the outer peripheral wall 6. The lead wire 12 of the thermistor 10 passes through the filling portion 9. When the filling portion 9 is filled with the adhesive 40 and hardened, the lead wire 12 is fixed and insulated. Thereby, even if the impact by vibration etc. acts, the lead wire 12 does not vibrate and it can prevent that the lead wire 12 is disconnected.

  And the adhesive 50 is filled so that the upper part of the adhesive 40 may be covered. Since the adhesive 50 has a higher viscosity than the adhesive 40, the adhesive 50 is cured while remaining in the filled position. Since the adhesive 50 is filled so as to cover the power line 3, the sensor line 21, the resistor 30, and the post 20, the power line 3 and the sensor line 21 are fixed in place, vibrations, etc. Therefore, it is possible to prevent the thermistor 10 and the resistor 30 from being disconnected and the lead wire 31 from being disconnected.

  In addition, there is no possibility that foreign matter such as powder generated by brushing between the power line 3 and the sensor line 21 is attached. Therefore, insulation between the power line 3 and the sensor line 21 is ensured, and a short circuit can be prevented.

  As described above, the temperature of the brush holder 2 can be detected by the thermistor 10 by sequentially filling the adhesives 40 and 50 having two different characteristics, and the thermistor 10 and the resistor 30 due to vibration or the like. And disconnection of the lead wires 12 and 31 can be prevented.

  According to the above embodiment, the following effects are obtained.

  According to the present invention, in the thermistor 10, the lead wire 12 is fixed to the post 20 whose base end 23 is fitted and fixed to the brush mount 1. Therefore, the lead wire 12 may be fixed to the post 20 at the time of assembly. Further, since the lead wire 12 of the thermistor 10, the lead wire 31 of the resistor 30, and the sensor wire 21 need only be bound to the post 20, the thermistor 10, the resistor 30, and the lead wire 31 can be easily assembled. It can be carried out.

  Also, by filling two different types of adhesives 40 and 50, the temperature of the brush holder 2 can be detected by the thermistor 10, and the thermistor 10 and the resistor 30 are detached due to vibrations or the lead wires 12 and 31. Disconnection can be prevented.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The electric motor according to the present invention can be used as a general-purpose brushed electric motor even in an environment with a lot of vibrations.

DESCRIPTION OF SYMBOLS 100 Electric motor 1 Brush mount 2 Brush holder 3 Power line 5 Inner wall 6 Outer wall 7 Notch 10 Thermistor 20 Post 21 Sensor line 30 Resistor 40 Adhesive 50 Adhesive

Claims (2)

A rotor that is rotatable relative to the brush mount;
A plurality of brushes fixed to the brush mount so as to be movable back and forth toward the rotor and in sliding contact with the rotor;
A brush holder attached to the brush mount and slidably supporting the brush;
Fixed by an adhesive filled between the brush holder and temperature detecting means for detecting the temperature of the brush, and
The adhesive is
A first adhesive that transfers heat of the brush to the temperature detection means;
An electric motor comprising: a second adhesive filled in an upper part of the first adhesive and having a viscosity higher than that of the first adhesive.   The electric motor according to claim 1, wherein the brush mount is formed with a regulation wall that regulates the outflow of the first adhesive.