JPWO2014002262A1 - DC motor - Google Patents

Abstract

The stepped brush 4 having the stepped portion 4a is urged by the spring 5 and slides in contact with the outer peripheral surface of the commutator 3 that rotates about the rotation axis X. Initially, the tip of the brush 4 contacts the brush sliding surface A of the commutator 3. When the brush 4 is worn due to secular change, the stepped portion 4a comes into contact with the commutator 3, and the contact is displaced from the brush sliding surface A to the non-sliding brush sliding surface B with the wear.

Description

  The present invention relates to a DC motor that supplies power when a brush connected to a power source slides in contact with a rotating commutator.

  In a conventional DC motor with a brush in which a commutator and a rotor are integrated, a brush that is supplied with a DC current from an external power source contacts the commutator and energizes, and power is supplied from the commutator to the rotor coil. This commutator has a segmented outer peripheral surface, and has a structure in which contact energization between the brush and each segment and energization from each segment to the coil are switched by rotation of the rotor.

  In such a DC motor, a rectangular parallelepiped brush is urged toward the commutator side and contacts the outer peripheral surface of the commutator, and slides on the same outer peripheral surface throughout the lifetime. Therefore, the tip shape of the brush wears over time, and changes between the initial state and the entire worn state after aging. Then, in the initial state, when the brush that is in contact with the optimum design point at which the noise level can be reduced most is worn due to aging, the brush comes into contact at a position deviated from the optimum design point, resulting in disturbance of rectification. In order to solve this problem, for example, in Patent Document 1, the shape of the brush is recessed on the opposite side of the commutator between the protrusions protruding from the commutator side at both ends in the rotational direction of the rotor. The shape has a concave portion. As a result, the protrusion comes into contact with the commutator both in the initial state and in the total wear state, so that positional deviation does not occur and rectification disturbance can be suppressed.

JP 2011-72050 A

  In the conventional DC motor including the above-mentioned Patent Document 1, since the brush slides on the same outer peripheral surface of the commutator, surface roughness and fouling occur on the outer peripheral surface of the commutator. The contact state of is worsened. Since the brush and the commutator are in contact with each other, if the contact state deteriorates, there is a problem that the motor performance is lowered due to the decrease in conductivity, or the wear of the brush is promoted.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a DC motor that prevents deterioration of the contact state and improves the reduction in motor performance and the promotion of brush wear.

  A DC motor according to the present invention includes a commutator that rotates integrally with a rotor around a rotating shaft, a brush that contacts and slides on the outer peripheral surface of the commutator, and an urging force that biases the brush toward the commutator. The brush has a shape in which the contact point of the brush with the commutator is displaced in the direction of the rotation axis on the outer peripheral surface in accordance with the shape change due to wear of the end portion contacting the outer peripheral surface of the commutator. is there.

  According to the present invention, the contact is displaced in the direction of the rotation axis on the outer peripheral surface in accordance with the shape change due to the wear of the brush end portion that contacts the outer peripheral surface of the commutator, thereby causing deterioration such as surface roughness and fouling. The contact point can be moved from the outer peripheral surface region to the outer peripheral surface region where no deterioration has occurred, and deterioration of the contact state can be prevented. Therefore, it is possible to provide a direct current motor with improved motor performance and improved brush wear.

It is a longitudinal cross-sectional view which shows the structure of the direct-current motor which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the rectification | straightening part used for the DC motor which concerns on Embodiment 1, and represents an initial state. It is a figure which shows the structure of the rectification | straightening part used for the DC motor which concerns on Embodiment 1, and represents a contact displacement state. It is a figure which shows the structure of the rectification | straightening part used for the DC motor which concerns on Embodiment 1, and represents all the wear states. It is a figure which shows the modification of the rectification | straightening part used for the direct-current motor which concerns on Embodiment 1. FIG. It is a figure which shows the modification of the rectification | straightening part used for the direct-current motor which concerns on Embodiment 1. FIG. It is a figure which shows the modification of the rectification | straightening part used for the direct-current motor which concerns on Embodiment 1. FIG.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
A DC motor 1 shown in FIG. 1 includes a commutator 3 that is fixed to one end of a rotor 2 and rotates integrally with the rotor 2, a brush 4 that slides on the outer peripheral surface of the commutator 3, and a brush 4 that is connected to the commutator 3. It has a rectification part comprised from the spring (biasing member) 5 urged | biased to a direction. The brush 4 and the spring 5 are accommodated in a brush holder 6.

  Although not visible in FIG. 1, the DC motor 1 is provided with two brushes 4 on the positive electrode side and the negative electrode side. When a direct current supplied from an external power source via the power supply terminal 8 flows into the brush 4 on the positive electrode side via the lead wire 7 and is energized from the brush 4 to the commutator 3, it is rectified by the commutator 3. It is supplied to the coil 9 of the rotor 2. When a magnetic flux is generated by energizing the coil 9, a rotational force is generated in the rotor 2 by the action of the magnetic pole of the permanent magnet 11 fixed to the housing 10, and the rotor 2 and the commutator 3 rotate about the rotation axis X. . Further, the current flowing through the coil 9 flows from the commutator 3 to the brush 4 on the negative electrode side.

Next, details of the rectification unit will be described.
FIG. 2A shows a plan view of the rectification unit, and FIGS. 2B, 3 and 4 show front views of the rectification unit. 2 is an initial state in which the brush 4 is not worn, FIG. 3 is a contact displacement state in which the brush 4 is worn to the stepped portion 4a and the contact is displaced in the direction of the rotation axis X, and FIG. This represents the entire wear state in which the brush 4 has been worn.

  Conductive segments 3 a to 3 f are arranged on the outer peripheral surface of the commutator 3 along the circumferential direction. Each segment 3 a to 3 f is electrically connected to the coil 9 of the rotor 2.

  Each brush 4 on the positive electrode side and the negative electrode side is not a rectangular parallelepiped shape as in the prior art, but a stepped shape having a stepped portion 4a. When the brush 4 is installed such that its longitudinal direction is along the orthogonal direction of the rotation axis X, the stepped portion 4a forms a step in the direction of the rotation axis X. In the illustrated example, the stepped portion 4 a has a shape inclined with respect to the outer peripheral surface of the commutator 3. By making the stepped portion 4a into an inclined shape, the overall length of the brush 4 becomes longer than that of a conventional rectangular parallelepiped brush. The brush 4 and the spring 5 are installed in the brush holder 6, and the spring 5 biases the rear end portion of the brush 4, so that the tip end portion of the brush 4 comes into pressure contact with the outer peripheral surface of the commutator 3. Therefore, as the commutator 3 rotates, the tip of the brush 4 is brought into contact with the segments 3a to 3f in turn and is electrically connected to the coil 9 of the rotor 2 connected to the segments 3a to 3f.

  The brush holder 6 is a substantially rectangular parallelepiped hole that accommodates the brush 4 and the spring 5, and holds the posture of the brush 4 by contacting the inner wall surface with the brush 4. Further, a notch 6 a is formed on one surface of the brush holder 6, and a lead wire 7 that electrically connects the brush 4 and the power supply terminal 8 is drawn out.

  In the initial state shown in FIG. 2, the tip of the brush 4 slides in contact with the hatched area of the outer peripheral surface of the commutator 3. This region is referred to as a brush sliding surface A. Since the brush 4 is biased toward the commutator 3 by the spring 5, the brush 4 moves toward the commutator 3 as the tip part wears.

  When the brush 4 is worn due to secular change, and the stepped portion 4a contacts and slides on the outer peripheral surface of the commutator 3, as shown in FIG. Therefore, the contact between the brush 4 and the commutator 3 is displaced in the direction of the rotation axis X, that is, from the brush sliding surface A to the non-sliding brush sliding surface B with wear. In this contact displacement state, since the stepped portion 4a is inclined with respect to the outer peripheral surface of the commutator 3, the area of the sliding region of the commutator 3 and the brush 4 shown by hatching in FIG. It increases from the area of the brush sliding surface A indicated by the oblique lines (and the brush sliding surface B indicated by the oblique lines in FIG. 4 described later). For this reason, even if the contact state is deteriorated due to surface roughness and fouling on the brush sliding surface A of the commutator 3, the contact area increases in the contact displacement state, improving the conductivity and the motor. Performance reduction can be suppressed. In this contact displacement state, the contact area increases while the urging force of the spring 5 remains the same, so the surface pressure is reduced and the brush 4 is less likely to be worn.

  When the brush 4 further wears due to secular change and reaches the full wear state shown in FIG. 4, the rear end portion of the brush 4 slides in contact with the region indicated by the oblique lines in the outer peripheral surface of the commutator 3. This region is defined as a brush sliding surface B. In this way, the contact between the commutator 3 and the brush 4 is displaced from the brush sliding surface A to the brush sliding surface B by utilizing the wear of the brush 4 due to aging. As a result, even if the brush sliding surface A is deteriorated due to secular change in the first half of the life of the DC motor 1, the brush 4 is placed on the brush sliding surface B that does not deteriorate in the second half of the life. Slide. Therefore, it becomes possible to prevent deterioration of the contact state due to secular change, and it is possible to improve deterioration of continuity and motor performance. Further, by preventing the contact state from deteriorating, the brush 4 is less likely to be worn, and the life of the DC motor 1 can be extended.

  As described above, according to the first embodiment, the DC motor 1 includes the commutator 3 that rotates integrally with the rotor 2 around the rotation axis X, and the brush that contacts and slides on the outer peripheral surface of the commutator 3. 4 and a spring 5 that urges the brush 4 toward the commutator 3. The brush 4 has a stepped shape having a stepped portion 4 a in the direction of the rotation axis X, and contacts the outer peripheral surface of the commutator 3. The contact of the brush 4 with the commutator 3 is displaced on the outer peripheral surface in the direction of the rotation axis X in accordance with the shape change due to wear at the end. For this reason, the contact point of the brush 4 and the commutator 3 can be moved from the brush sliding surface A to the non-sliding brush sliding surface B along with aging. As a result, it is possible to prevent the contact state between the brush 4 and the commutator 3 from being deteriorated, and to improve the electrical conductivity, suppress the reduction in motor performance, and suppress the wear of the brush 4.

  Further, according to the first embodiment, the stepped portion 4 a of the brush 4 is inclined with respect to the outer peripheral surface of the commutator 3. For this reason, the full length of the brush 4 becomes long compared with the conventional rectangular parallelepiped brush. As a result, it is possible to obtain a life extension effect against the wear of the brush 4 and to extend the life of the DC motor 1.

The brush 4 may have a shape other than that shown in FIGS. Hereinafter, modified examples of the brush 4 will be described with reference to FIGS.
The brush 4 shown in FIG. 5 has a stepped shape having a stepped portion 4a. In addition, the brush 4 has an inclined surface 4b inclined with respect to the outer peripheral surface of the commutator 3 in addition to the stepped shape. . When the spring 5 biases the inclined surface 4b, the biasing direction becomes obliquely downward.
In the contact displacement state as shown in FIG. 3, since the brush holder 6 cannot hold the upper surface of the brush 4, the brush 4 may rattle upward. On the other hand, as shown in FIG. 5, the urging direction is inclined downward, which has an effect of suppressing rattling by pressing the lower surface of the brush 4 against the brush holder 6 even in a contact change state.

The brush 4 shown in FIG. 6 has a stepped shape having a stepped portion 4 a, and the stepped portion 4 a is formed in parallel with the outer peripheral surface of the commutator 3. Also in the case of this configuration, the contact point between the commutator 3 and the brush 4 can be displaced with the wear of the brush 4 as in the case of the brush 4 shown in FIGS. Therefore, it is possible to prevent the contact state between the brush 4 and the commutator 3 from being deteriorated, and it is possible to improve the conductivity, suppress the decrease in motor performance, and suppress the wear of the brush 4.
In the case of the brush 4 having the shape shown in FIG. 6, since the difference between the contact area in the initial state and the total wear state and the contact area in the contact displacement state is large, the energization characteristics to the coil 9 may change. . Therefore, in order to reduce the change in characteristics, it is desirable to reduce the width W of the step portion 4a and shorten the period during which the step portion 4a contacts the commutator 3.

The brush 4 shown in FIG. 7 has a substantially rectangular parallelepiped shape, not a stepped shape, and is installed in an inclined state with respect to the outer peripheral surface of the commutator 3. Also in the case of this configuration, like the brush 4 shown in FIGS. 1 to 4, the contact between the commutator 3 and the brush 4 can be displaced with the wear of the brush 4, and conductivity due to deterioration of the contact state. It is possible to suppress deterioration of the motor and decrease in motor performance.
In addition, by installing the brush 4 in an inclined state, the overall length of the brush 4 can be increased compared to the case where a rectangular parallelepiped brush is installed perpendicularly to the outer peripheral surface of the commutator 3 as in the prior art. Thus, the life of the brush 4 can be prolonged and the life of the DC motor 1 can be extended.

In the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted within the scope of the invention.
For example, in FIG. 1 to FIG. 7, the spring 5 is used as an example of a member that biases the brush 4, but the present invention is not limited to this, and any biasing member such as a leaf spring can be used.
Further, for example, the DC motor 1 to which the brush 4 of the first embodiment is applied is not limited to the configuration shown in FIG.

  As described above, the direct current motor according to the present invention prevents the deterioration of the contact state between the brush and the commutator and improves the durability, so that the brush comes into contact with and slides on the outer peripheral surface of the commutator. Suitable for use in DC motors.

  1 DC motor, 2 rotor, 3 commutator, 3a to 3f segment, 4 brush, 4a stepped part, 4b inclined surface, 5 spring, 6 brush holder, 6a notch, 7 lead wire, 8 feed terminal, 9 coil, 10 Housing, 11 permanent magnet.

  The present invention relates to a DC motor that supplies power when a brush connected to a power source slides in contact with a rotating commutator.

  In a conventional DC motor with a brush in which a commutator and a rotor are integrated, a brush that is supplied with a DC current from an external power source contacts the commutator and energizes, and power is supplied from the commutator to the rotor coil. This commutator has a segmented outer peripheral surface, and has a structure in which contact energization between the brush and each segment and energization from each segment to the coil are switched by rotation of the rotor.

  In such a DC motor, a rectangular parallelepiped brush is urged toward the commutator side and contacts the outer peripheral surface of the commutator, and slides on the same outer peripheral surface throughout the lifetime. Therefore, the tip shape of the brush wears over time, and changes between the initial state and the entire worn state after aging. Then, in the initial state, when the brush that is in contact with the optimum design point at which the noise level can be reduced most is worn due to aging, the brush comes into contact at a position deviated from the optimum design point, resulting in disturbance of rectification. In order to solve this problem, for example, in Patent Document 1, the shape of the brush is recessed on the opposite side of the commutator between the protrusions protruding from the commutator side at both ends in the rotational direction of the rotor. The shape has a concave portion. As a result, the protrusion comes into contact with the commutator both in the initial state and in the total wear state, so that positional deviation does not occur and rectification disturbance can be suppressed.

JP 2011-72050 A

  In the conventional DC motor including the above-mentioned Patent Document 1, since the brush slides on the same outer peripheral surface of the commutator, surface roughness and fouling occur on the outer peripheral surface of the commutator. The contact state of is worsened. Since the brush and the commutator are in contact with each other, if the contact state deteriorates, there is a problem that the motor performance is lowered due to the decrease in conductivity, or the wear of the brush is promoted.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a DC motor that prevents deterioration of the contact state and improves the reduction in motor performance and the promotion of brush wear.

A DC motor according to the present invention includes a commutator that rotates integrally with a rotor around a rotating shaft, a brush that contacts and slides on the outer peripheral surface of the commutator, and an urging force that biases the brush toward the commutator. The brush has a shape in which the contact point of the brush with the commutator is displaced in the direction of the rotation axis on the outer peripheral surface in accordance with the shape change due to wear at the end contacting the outer peripheral surface of the commutator ; and It is a stepped shape having a step portion in the direction of the rotation axis .

  According to the present invention, the contact is displaced in the direction of the rotation axis on the outer peripheral surface in accordance with the shape change due to the wear of the brush end portion that contacts the outer peripheral surface of the commutator, thereby causing deterioration such as surface roughness and fouling. The contact point can be moved from the outer peripheral surface region to the outer peripheral surface region where no deterioration has occurred, and deterioration of the contact state can be prevented. Therefore, it is possible to provide a direct current motor with improved motor performance and improved brush wear.

It is a longitudinal cross-sectional view which shows the structure of the direct-current motor which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the rectification | straightening part used for the DC motor which concerns on Embodiment 1, and represents an initial state. It is a figure which shows the structure of the rectification | straightening part used for the DC motor which concerns on Embodiment 1, and represents a contact displacement state. It is a figure which shows the structure of the rectification | straightening part used for the DC motor which concerns on Embodiment 1, and represents all the wear states. It is a figure which shows the modification of the rectification | straightening part used for the direct-current motor which concerns on Embodiment 1. FIG. It is a figure which shows the modification of the rectification | straightening part used for the direct-current motor which concerns on Embodiment 1. FIG. It is a figure which shows the modification of the rectification | straightening part used for the direct-current motor which concerns on Embodiment 1. FIG.

Embodiment 1 FIG.
A DC motor 1 shown in FIG. 1 includes a commutator 3 that is fixed to one end of a rotor 2 and rotates integrally with the rotor 2, a brush 4 that slides on the outer peripheral surface of the commutator 3, and a brush 4 that is connected to the commutator 3. It has a rectification part comprised from the spring (biasing member) 5 urged | biased to a direction. The brush 4 and the spring 5 are accommodated in a brush holder 6.

  Although not visible in FIG. 1, the DC motor 1 is provided with two brushes 4 on the positive electrode side and the negative electrode side. When a direct current supplied from an external power source via the power supply terminal 8 flows into the brush 4 on the positive electrode side via the lead wire 7 and is energized from the brush 4 to the commutator 3, it is rectified by the commutator 3. It is supplied to the coil 9 of the rotor 2. When a magnetic flux is generated by energizing the coil 9, a rotational force is generated in the rotor 2 by the action of the magnetic pole of the permanent magnet 11 fixed to the housing 10, and the rotor 2 and the commutator 3 rotate about the rotation axis X. . Further, the current flowing through the coil 9 flows from the commutator 3 to the brush 4 on the negative electrode side.

Next, details of the rectification unit will be described.
FIG. 2A shows a plan view of the rectification unit, and FIGS. 2B, 3 and 4 show front views of the rectification unit. 2 is an initial state in which the brush 4 is not worn, FIG. 3 is a contact displacement state in which the brush 4 is worn to the stepped portion 4a and the contact is displaced in the direction of the rotation axis X, and FIG. This represents the entire wear state in which the brush 4 has been worn.

  Conductive segments 3 a to 3 f are arranged on the outer peripheral surface of the commutator 3 along the circumferential direction. Each segment 3 a to 3 f is electrically connected to the coil 9 of the rotor 2.

  Each brush 4 on the positive electrode side and the negative electrode side is not a rectangular parallelepiped shape as in the prior art, but a stepped shape having a stepped portion 4a. When the brush 4 is installed such that its longitudinal direction is along the orthogonal direction of the rotation axis X, the stepped portion 4a forms a step in the direction of the rotation axis X. In the illustrated example, the stepped portion 4 a has a shape inclined with respect to the outer peripheral surface of the commutator 3. By making the stepped portion 4a into an inclined shape, the overall length of the brush 4 becomes longer than that of a conventional rectangular parallelepiped brush. The brush 4 and the spring 5 are installed in the brush holder 6, and the spring 5 biases the rear end portion of the brush 4, so that the tip end portion of the brush 4 comes into pressure contact with the outer peripheral surface of the commutator 3. Therefore, as the commutator 3 rotates, the tip of the brush 4 is brought into contact with the segments 3a to 3f in turn and is electrically connected to the coil 9 of the rotor 2 connected to the segments 3a to 3f.

  The brush holder 6 is a substantially rectangular parallelepiped hole that accommodates the brush 4 and the spring 5, and holds the posture of the brush 4 by contacting the inner wall surface with the brush 4. Further, a notch 6 a is formed on one surface of the brush holder 6, and a lead wire 7 that electrically connects the brush 4 and the power supply terminal 8 is drawn out.

  In the initial state shown in FIG. 2, the tip of the brush 4 slides in contact with the hatched area of the outer peripheral surface of the commutator 3. This region is referred to as a brush sliding surface A. Since the brush 4 is biased toward the commutator 3 by the spring 5, the brush 4 moves toward the commutator 3 as the tip part wears.

  When the brush 4 is worn due to secular change, and the stepped portion 4a contacts and slides on the outer peripheral surface of the commutator 3, as shown in FIG. Therefore, the contact between the brush 4 and the commutator 3 is displaced in the direction of the rotation axis X, that is, from the brush sliding surface A to the non-sliding brush sliding surface B with wear. In this contact displacement state, since the stepped portion 4a is inclined with respect to the outer peripheral surface of the commutator 3, the area of the sliding region of the commutator 3 and the brush 4 shown by hatching in FIG. It increases from the area of the brush sliding surface A indicated by the oblique lines (and the brush sliding surface B indicated by the oblique lines in FIG. 4 described later). For this reason, even if the contact state is deteriorated due to surface roughness and fouling on the brush sliding surface A of the commutator 3, the contact area increases in the contact displacement state, improving the conductivity and the motor. Performance reduction can be suppressed. In this contact displacement state, the contact area increases while the urging force of the spring 5 remains the same, so the surface pressure is reduced and the brush 4 is less likely to be worn.

  When the brush 4 further wears due to secular change and reaches the full wear state shown in FIG. 4, the rear end portion of the brush 4 slides in contact with the region indicated by the oblique lines in the outer peripheral surface of the commutator 3. This region is defined as a brush sliding surface B. In this way, the contact between the commutator 3 and the brush 4 is displaced from the brush sliding surface A to the brush sliding surface B by utilizing the wear of the brush 4 due to aging. As a result, even if the brush sliding surface A is deteriorated due to secular change in the first half of the life of the DC motor 1, the brush 4 is placed on the brush sliding surface B that does not deteriorate in the second half of the life. Slide. Therefore, it becomes possible to prevent deterioration of the contact state due to secular change, and it is possible to improve deterioration of continuity and motor performance. Further, by preventing the contact state from deteriorating, the brush 4 is less likely to be worn, and the life of the DC motor 1 can be extended.

  As described above, according to the first embodiment, the DC motor 1 includes the commutator 3 that rotates integrally with the rotor 2 around the rotation axis X, and the brush that contacts and slides on the outer peripheral surface of the commutator 3. 4 and a spring 5 that urges the brush 4 toward the commutator 3. The brush 4 has a stepped shape having a stepped portion 4 a in the direction of the rotation axis X, and contacts the outer peripheral surface of the commutator 3. The contact of the brush 4 with the commutator 3 is displaced on the outer peripheral surface in the direction of the rotation axis X in accordance with the shape change due to wear at the end. For this reason, the contact point of the brush 4 and the commutator 3 can be moved from the brush sliding surface A to the non-sliding brush sliding surface B along with aging. As a result, it is possible to prevent the contact state between the brush 4 and the commutator 3 from being deteriorated, and to improve the electrical conductivity, suppress the reduction in motor performance, and suppress the wear of the brush 4.

  Further, according to the first embodiment, the stepped portion 4 a of the brush 4 is inclined with respect to the outer peripheral surface of the commutator 3. For this reason, the full length of the brush 4 becomes long compared with the conventional rectangular parallelepiped brush. As a result, it is possible to obtain a life extension effect against the wear of the brush 4 and to extend the life of the DC motor 1.

The brush 4 may have a shape other than that shown in FIGS. Hereinafter, modified examples of the brush 4 will be described with reference to FIGS.
The brush 4 shown in FIG. 5 has a stepped shape having a stepped portion 4a. In addition, the brush 4 has an inclined surface 4b inclined with respect to the outer peripheral surface of the commutator 3 in addition to the stepped shape. . When the spring 5 biases the inclined surface 4b, the biasing direction becomes obliquely downward.
In the contact displacement state as shown in FIG. 3, since the brush holder 6 cannot hold the upper surface of the brush 4, the brush 4 may rattle upward. On the other hand, as shown in FIG. 5, the urging direction is inclined downward, which has an effect of suppressing rattling by pressing the lower surface of the brush 4 against the brush holder 6 even in a contact change state.

The brush 4 shown in FIG. 6 has a stepped shape having a stepped portion 4 a, and the stepped portion 4 a is formed in parallel with the outer peripheral surface of the commutator 3. Also in the case of this configuration, the contact point between the commutator 3 and the brush 4 can be displaced with the wear of the brush 4 as in the case of the brush 4 shown in FIGS. Therefore, it is possible to prevent the contact state between the brush 4 and the commutator 3 from being deteriorated, and it is possible to improve the conductivity, suppress the decrease in motor performance, and suppress the wear of the brush 4.
In the case of the brush 4 having the shape shown in FIG. 6, since the difference between the contact area in the initial state and the total wear state and the contact area in the contact displacement state is large, the energization characteristics to the coil 9 may change. . Therefore, in order to reduce the change in characteristics, it is desirable to reduce the width W of the step portion 4a and shorten the period during which the step portion 4a contacts the commutator 3.

The brush 4 shown in FIG. 7 has a substantially rectangular parallelepiped shape, not a stepped shape, and is installed in an inclined state with respect to the outer peripheral surface of the commutator 3. Also in the case of this configuration, like the brush 4 shown in FIGS. 1 to 4, the contact between the commutator 3 and the brush 4 can be displaced with the wear of the brush 4, and conductivity due to deterioration of the contact state. It is possible to suppress the deterioration of the motor performance and the motor performance.
In addition, by installing the brush 4 in an inclined state, the overall length of the brush 4 can be increased compared to the case where a rectangular parallelepiped brush is installed perpendicularly to the outer peripheral surface of the commutator 3 as in the prior art. Thus, the life of the brush 4 can be prolonged and the life of the DC motor 1 can be extended.

In the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted within the scope of the invention.
For example, in FIG. 1 to FIG. 7, the spring 5 is used as an example of a member that biases the brush 4, but the present invention is not limited to this, and any biasing member such as a leaf spring can be used.
Further, for example, the DC motor 1 to which the brush 4 of the first embodiment is applied is not limited to the configuration shown in FIG.

  1 DC motor, 2 rotor, 3 commutator, 3a to 3f segment, 4 brush, 4a stepped part, 4b inclined surface, 5 spring, 6 brush holder, 6a notch, 7 lead wire, 8 feed terminal, 9 coil, 10 Housing, 11 permanent magnet.

A DC motor according to the present invention includes a commutator that rotates integrally with a rotor around a rotating shaft, a brush that contacts and slides on the outer peripheral surface of the commutator, and an urging force that biases the brush toward the commutator. The brush has a shape in which the contact point of the brush with the commutator is displaced in the direction of the rotation axis on the outer peripheral surface in accordance with the shape change due to wear at the end contacting the outer peripheral surface of the commutator; and A stepped portion is provided in the direction of the rotation axis, and the stepped shape increases the contact area in a state where the contact point of the brush is displaced .

Claims (3)

A commutator that rotates integrally with the rotor around the rotation axis;
A brush that slides in contact with the outer peripheral surface of the commutator;
A biasing member that biases the brush toward the commutator side,
The brush has a shape in which a contact point of the brush with respect to the commutator is displaced in the direction of the rotation axis on the outer peripheral surface in accordance with a shape change due to wear of an end portion contacting the outer peripheral surface of the commutator. DC motor features.   2. The DC motor according to claim 1, wherein the brush has a stepped shape having a step portion in the rotation axis direction.   The DC motor according to claim 2, wherein the step portion has a shape inclined with respect to the outer peripheral surface of the commutator.

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