Brushes of a brushed motor, and brushed motor

Abstract

To provide a brush for a motor with a brush, capable of suppressing generation of metal abrasion powder due to a commutator coming into slide contact with the brush, and to provide the motor with the brush.SOLUTION: A brush 60 for a motor 20 with a brush comprises a positive electrode brush part 65 and a negative electrode brush part 66 with which a commutator 50 comes into slide contact. A positive slide contact face 64a is formed on the positive electrode brush part 65. A negative slide contact face 64b is formed on the negative electrode brush part 66. The positive slide contact face 64a and the negative slide contact face 64b each are formed, using conductive rubber.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a brush and a brush-type motor.

Background Art

[0002] A brush-type motor includes a commutator that rotates integrally with a rotating shaft, and a brush that makes sliding contact with the commutator. For power supply from the brush to the commutator, the brush and the commutator are generally made of metal. Therefore, metal wear powder is generated from the brush and the commutator due to the sliding contact of the commutator with the brush.

[0003] For example, as disclosed in Patent Document 1, a commutator as a commutator is formed by filling an insulating material between commutator segments, and the outer peripheral surface of the commutator segment and the outer peripheral surface of the insulating material are located on the same surface. Thereby, since the contact between the commutator and the brush is smoothly performed, wear is reduced and the generation of metal wear powder is suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a brush-type motor, it is desired to suppress the generation of metal wear powder due to the sliding contact of the commutator with the brush.

Means for Solving the Problems

[0006] The brush for a brushed motor that solves the above problems is a brush for a brushed motor equipped with a commutator, comprising a positive electrode brush portion and a negative electrode brush portion that the commutator slides against, the positive electrode brush portion having a positive electrode sliding contact surface that the commutator slides against, and the negative electrode brush portion having a negative electrode sliding contact surface that the commutator slides against, and the positive electrode sliding contact surface and the negative electrode sliding contact surface are formed using conductive rubber.

[0007] According to this, the conductive rubber on the positive electrode and negative electrode sliding surfaces ensures electrical conductivity between the positive electrode brush section and the commutator. Furthermore, compared to a case where the positive electrode and negative electrode sliding surfaces are entirely made of metal, the generation of metal wear particles when the commutator slides against the positive electrode and negative electrode sliding surfaces can be suppressed.

[0008] Regarding the brushes of a brushed motor, the brushes and the commutator are annular in shape, and the brush has an insulating portion interposed between the positive electrode brush portion and the negative electrode brush portion in the circumferential direction of the brush to insulate the positive electrode brush portion from the negative electrode brush portion, and the insulating portion is made of insulating rubber, and the brush may be pressed against the outer circumferential surface of the commutator over its entire circumferential direction and may have a sliding contact surface including the positive electrode sliding contact surface and the negative electrode sliding contact surface.

[0009] According to this, the sliding surface of the brush can be pressed against the outer surface of the commutator over its entire circumference. This allows for a seal between the sliding surface of the brush and the outer surface of the commutator. Regarding the brushes of a brushed motor, the brushed motor is mounted on an electric compressor, the electric compressor comprises a rotating shaft to which the commutator is fixed, a compression unit that compresses the refrigerant by the rotation of the rotating shaft, and a housing that defines a motor housing chamber for housing the brushed motor, the refrigerant before being compressed by the compression unit is drawn into the motor housing chamber through an intake port formed in the housing, the brush comprises a mounting portion that contacts the entire circumferential surface of the inner circumferential surface of the housing, an annular extension portion that extends from the mounting portion toward the commutator along the radial direction of the rotating shaft, and an annular lip portion that extends from the extension portion toward the commutator and is inclined to approach the compression unit as it approaches the commutator from the extension portion, the lip portion may have the sliding contact surface.

[0010] According to this, the pressure of the refrigerant drawn into the motor housing acts on the lip portion. The sliding surface of the lip portion is pressed against the outer surface of the commutator by the pressure of the refrigerant. Therefore, the sliding surface of the brush can be pressed against the outer surface of the commutator by the pressure of the refrigerant.

[0011] The brushed motor for solving the above problems comprises a commutator and brushes that the commutator slides against, wherein the brushes include a positive electrode brush portion and a negative electrode brush portion that the commutator slides against, and the positive electrode sliding contact surface of the positive electrode brush portion and the negative electrode sliding contact surface of the negative electrode brush portion are each formed using conductive rubber.

[0012] According to this, the conductive rubber on the positive electrode and negative electrode sliding surfaces ensures electrical conductivity between the positive electrode brush section and the commutator. Furthermore, compared to a case where the positive electrode and negative electrode sliding surfaces are entirely made of metal, the generation of metal wear particles when the commutator slides against the positive electrode and negative electrode sliding surfaces can be suppressed. [Effects of the Invention]

[0013] This invention can suppress the generation of metal wear particles associated with the sliding contact of the commutator with the brush. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a schematic cross-sectional view showing a brushed motor of an electric compressor. [Figure 2] Figure 2 is a schematic diagram showing the commutator and brushes. [Figure 3] Figure 3 is a cross-sectional view showing the brush. [Figure 4] Figure 4 is a cross-sectional view showing another example of a brush. [Modes for carrying out the invention]

[0015] Hereinafter, an embodiment of the brushes of a brushed motor and a brushed motor, specifically those of a brushed motor mounted on an electric compressor, will be described with reference to Figures 1 to 3.

[0016] As shown in Figure 1, the electric compressor 10 is used in the vehicle-mounted air conditioning system 101. <Vehicle air conditioner> The on-board air conditioning system 101 is installed in a vehicle (not shown). The on-board air conditioning system 101 comprises an electric compressor 10 and an external refrigerant circuit 102. The external refrigerant circuit 102 supplies refrigerant as a fluid to the electric compressor 10. The external refrigerant circuit 102 includes, for example, a heat exchanger and an expansion valve. The on-board air conditioning system 101 provides heating and cooling inside the vehicle. Heating and cooling inside the vehicle are achieved by compressing the refrigerant with the electric compressor 10, and by heat exchange and expansion of the refrigerant by the external refrigerant circuit 102.

[0017] <Electric Compressor> The electric compressor 10 comprises a housing 11, a rotating shaft 13, a compression unit 14, and a DC brushed motor 20. Therefore, the brushed motor 20 is mounted on the electric compressor 10.

[0018] The housing 11 houses a rotating shaft 13, a compression section 14, and a brush motor 20. The rotating shaft 13 rotates by the drive of the brush motor 20. The compression section 14 is connected to the rotating shaft 13. The compression section 14 compresses the refrigerant supplied from the external refrigerant circuit 102 when the rotating shaft 13 rotates. The compression section 14 discharges the compressed refrigerant to the external refrigerant circuit 102. The compression section 14 is realized by a configuration such as a scroll type, a piston type, a vane type, or the like.

[0019] The housing 11 includes a first housing component 15, a second housing component 16, and a third housing component 17. Each of the first housing component 15, the second housing component 16, and the third housing component 17 is made of metal. Each of the first housing component 15, the second housing component 16, and the third housing component 17 is made of, for example, aluminum.

[0020] The first housing component 15 includes a plate-like bottom wall 15a and a cylindrical peripheral wall 15b. The peripheral wall 15b extends from the outer peripheral portion of the bottom wall 15a in the thickness direction of the bottom wall 15a. The second housing component 16 is connected to the first housing component 15. The second housing component 16 closes the internal space of the first housing component 15 from the side opposite to the bottom wall 15a in the peripheral wall 15b of the first housing component 15. The first housing component 15 and the second housing component 16 define a motor housing chamber S1. The brush motor 20 is housed in the motor housing chamber S1. Therefore, the housing 11 defines a motor housing chamber S1 that houses the brush motor 20. An intake port 15d is formed in the peripheral wall 15b. The intake port 15d is connected to the external refrigerant circuit 102. The intake port 15d communicates with the motor housing chamber S1.

[0021] A cylindrical boss portion 15c is provided on the surface of the bottom wall 15a facing the motor housing chamber S1. A bearing 18 is provided inside the boss portion 15c. The boss portion 15c protrudes from the bottom wall 15a toward the second housing component 16.

[0022] The central axis of the boss portion 15c coincides with the central axis of the peripheral wall 15b. A cylindrical boss portion 16a is provided on the surface of the second housing structure 16 facing the motor housing chamber S1. A bearing 19 is provided inside the boss portion 16a. The boss portion 16a protrudes from the second housing structure 16 toward the bottom wall 15a. The central axis of the boss portion 16a coincides with the central axis of the peripheral wall 15b. Therefore, the central axis of the boss portion 15c and the central axis of the boss portion 16a coincide. The rotating shaft 13 is inserted through the bearing 18 of the boss portion 15c and the bearing 19 of the boss portion 16a. The rotating shaft 13 is rotatably supported in the housing 11 via the bearings 18 and 19.

[0023] A connecting passage 16b is formed in the second housing structure 16. The third housing structure 17 comprises an end wall 17a and a cylindrical peripheral wall 17b. The peripheral wall 17b extends from the outer periphery of the end wall 17a in the thickness direction of the end wall 17a. The third housing structure 17 is connected to the second housing structure 16. The second housing structure 16 and the third housing structure 17 define a compression section housing chamber S2. A compression section 14 is housed in the compression section housing chamber S2. A discharge port 17c is formed in the end wall 17a. The discharge port 17c is connected to an external refrigerant circuit 102. The discharge port 17c communicates with the compression section housing chamber S2. The compression section housing chamber S2 communicates with the motor housing chamber S1 by a communication passage 16b formed in the second housing structure 16.

[0024] The rotating shaft 13 extends through the second housing structure 16 into the compression section housing chamber S2. The compression section 14 is connected to the portion of the rotating shaft 13 that extends into the compression section housing chamber S2.

[0025] The refrigerant compressed by the compression unit 14 is discharged to the external refrigerant circuit 102 via the compression unit housing chamber S2 and the discharge port 17c. The refrigerant that has flowed through the external refrigerant circuit 102 is drawn into the motor housing chamber S1 via the suction port 15d. The refrigerant drawn into the motor housing chamber S1 is drawn into the compression unit housing chamber S2 via the communication passage 16b. Therefore, the refrigerant before being compressed by the compression unit 14 is drawn into the motor housing chamber S1 via the suction port 15d formed in the housing 11.

[0026] <Brushed motor> The brushed motor 20 comprises an armature core 30, a magnet 40, a commutator 50, and brushes 60.

[0027] The armature core 30 is fixed to the rotating shaft 13. The armature core 30 rotates integrally with the rotating shaft 13. Although not shown in detail in Figure 1, multiple coils 31 are wound around the armature core 30.

[0028] The magnet 40 is formed by combining multiple magnet pieces 41. The multiple magnet pieces 41 are fixed to the inner circumferential surface of the peripheral wall 15b of the first housing structure 15. The magnet 40 consists of magnet pieces 41 in which the peripheral wall 15b side of the magnet piece 41 is magnetized as a north pole and the armature core 30 side as a south pole, and magnet pieces 41 in which the peripheral wall 15b side is magnetized as a south pole and the armature core 30 side as a north pole, which are alternately arranged in the circumferential direction of the peripheral wall 15b.

[0029] The magnet 40 may be cylindrical and not divided into multiple magnet pieces 41. In a cylindrical magnet 40, multiple magnetic poles will be arranged adjacent to each other in the circumferential direction, but unmagnetized regions may be provided between these magnetic poles.

[0030] The commutator 50 is fixed to the rotating shaft 13. Therefore, the electric compressor 10 has a rotating shaft 13 to which the commutator 50 is fixed. The commutator 50 rotates integrally with the rotating shaft 13. The commutator 50 is adjacent to the armature core 30 in the axial direction of the rotating shaft 13. The commutator 50 is cylindrical. The commutator 50 is fixed to the outer circumferential surface of the rotating shaft 13.

[0031] As shown in Figure 2, the commutator 50 is annular. The commutator 50 comprises a plurality of commutator segments 51 and a plurality of insulating segments 52. In Figure 2, the insulating segments 52 are hatched to illustrate the boundaries between the commutator segments 51 and the insulating segments 52 in the commutator 50. Each of the plurality of commutator segments 51 is made of metal. The plurality of commutator segments 51 and the plurality of insulating segments 52 are arranged adjacent to each other in the circumferential direction of the rotation axis 13. The commutator segments 51 and insulating segments 52 are arranged alternately in the circumferential direction of the commutator 50. Although not shown, each of the plurality of commutator segments 51 is electrically connected to both ends of the coil 31.

[0032] <Brush> As shown in Figures 2 and 3, the brush 60 is in contact with the outer circumferential surface 50a of the commutator 50. The brush 60 is annular in shape. The brush 60 includes a mounting portion 61, an extension portion 62, and a lip portion 63.

[0033] The mounting portion 61 is cylindrical. The direction in which the central axis L of the mounting portion 61 extends is the axial direction of the brush 60. The central axis L coincides with the central axis of the rotation axis 13. The mounting portion 61 is press-fitted into the inside of the peripheral wall 15b of the first housing structure 15. The outer circumferential surface of the mounting portion 61 is in contact with the inner circumferential surface of the peripheral wall 15b over its entire circumferential direction. This contact seals the space between the inner circumferential surface of the peripheral wall 15b and the outer circumferential surface of the brush 60. A positioning ring 12 is mounted on the peripheral wall 15b of the first housing structure 15, on the side of the mounting portion 61 that is closer to the bottom wall 15a. The positioning ring 12 restricts the movement of the mounting portion 61 toward the bottom wall 15a.

[0034] The extension portion 62 extends from the end of the mounting portion 61 near the bottom wall 15a in the axial direction, along the radial direction of the brush 60, toward the rotating shaft 13 and the commutator 50. The extension portion 62 is disc-shaped. The dimension of the mounting portion 61 along the radial direction of the brush 60 is defined as the thickness of the mounting portion 61. The dimension of the extension portion 62 along the axial direction of the brush 60 is defined as the thickness of the extension portion 62. The thickness of the extension portion 62 may be the same as or different from the thickness of the mounting portion 61.

[0035] The lip portion 63 extends from the extension portion 62 toward the commutator 50. The lip portion 63 is bent relative to the extension portion 62. The lip portion 63 is conical in shape. As the lip portion 63 approaches the commutator 50 from the extension portion 62, it is inclined to approach the compression portion 14. The lip portion 63 has an inner lip portion surface 63a on the inner surface of the conical cylinder and an outer lip portion surface 63b on the outer surface of the conical cylinder. In the axial direction of the brush 60, the outer lip portion surface 63b is closer to the compression portion 14 than the inner lip portion surface 63a.

[0036] The thickness of the lip portion 63 is defined as the dimension from the outer surface 63b of the lip portion to the inner surface 63a of the lip portion, along a direction perpendicular to the outer surface 63b of the lip portion. The thickness of the lip portion 63 gradually decreases from the extension portion 62 towards the tip of the lip portion 63. In other words, the thickness of the lip portion 63 decreases as it approaches the compression portion 14 from the extension portion 62. The thickness of the lip portion 63 gradually decreases from the thickness of the extension portion 62 as it approaches the compression portion 14 from the extension portion 62. The lip portion 63 is more elastically deformable than the extension portion 62. The inner surface of the brush 60 is a sliding contact surface 64 against the outer surface 50a of the commutator 50. The sliding contact surface 64 is annular. The sliding contact surface 64 is formed by the tip surface of the lip portion 63. The brush 60 has a sliding contact surface 64 that is pressed against the outer surface 50a of the commutator 50 over the entire circumferential direction of the brush 60.

[0037] As shown in Figure 2, the brush 60 comprises a positive electrode brush portion 65, a negative electrode brush portion 66, and two insulating portions 67. The positive electrode brush portion 65, the negative electrode brush portion 66, and the insulating portions 67 are provided on the lip portion 63. The mounting portion 61 insulates the brush 60 from the housing 11.

[0038] The positive electrode brush section 65 and the negative electrode brush section 66 are facing each other radially in the brush 60 with the commutator 50 in between. The commutator 50 slides against the positive electrode brush section 65 and the negative electrode brush section 66. Each of the two insulating sections 67 is positioned between the positive electrode brush section 65 and the negative electrode brush section 66.

[0039] The positive electrode brush portion 65 is connected to the positive electrode of the power supply 70. The negative electrode brush portion 66 is connected to the negative electrode of the power supply 70. The insulating portion 67 is interposed between the positive electrode brush portion 65 and the negative electrode brush portion 66 in the circumferential direction of the brush 60, electrically insulating the positive electrode brush portion 65 and the negative electrode brush portion 66. The positive electrode brush portion 65, the negative electrode brush portion 66, and the two insulating portions 67 are arranged in the circumferential direction in the order of positive electrode brush portion 65, insulating portion 67, negative electrode brush portion 66, and insulating portion 67.

[0040] The sliding contact surface 64 comprises a positive electrode sliding contact surface 64a formed by the positive electrode brush portion 65, a negative electrode sliding contact surface 64b formed by the negative electrode brush portion 66, and an insulating sliding contact surface 64c formed by the insulating portion 67. The circumferential dimensions of the positive electrode sliding contact surface 64a and the negative electrode sliding contact surface 64b are longer than the circumferential dimensions of each insulating piece 52.

[0041] The circumferential dimensions of the positive electrode sliding contact surface 64a and the negative electrode sliding contact surface 64b are shorter than the circumferential dimensions of the commutator segment 51. Each of the positive electrode sliding contact surface 64a and the negative electrode sliding contact surface 64b is always in contact with one of the outer circumferential surfaces of the commutator segment 51, which is part of the outer circumferential surface 50a of the commutator 50.

[0042] The brush 60 is made of rubber. The mounting portion 61 and extension portion 62 of the brush 60 are made of insulating rubber. The positive electrode brush portion 65 and the negative electrode brush portion 66 of the lip portion 63 are made of conductive rubber, and the insulating portion 67 of the lip portion 63 is made of insulating rubber. Therefore, the entire surface of the positive electrode sliding contact surface 64a formed on the positive electrode brush portion 65 is made of conductive rubber. Also, the entire surface of the negative electrode sliding contact surface 64b formed on the negative electrode brush portion 66 is made of conductive rubber.

[0043] Conductive rubber is formed by mixing desired amounts of any rubber material, conductive particles, and conductive fibers. Examples of rubber materials include nitrile rubber, acrylic rubber, fluororubber, and silicone rubber. Conductive particles are conductive metal oxides such as carbon black, graphite, indium / tin oxide, and antimony / tin oxide. The conductive particles may also be selected from the above materials as appropriate. Conductive fibers include stainless steel fibers, carbon fibers, carbon tubing, and carbon fiber plated with potassium titanate. The thickness and length of the conductive fibers can be arbitrarily selected. Conductive rubber has relatively low electrical resistance. Note that conductive rubber may be formed from any rubber material and conductive particles, or from any rubber material and conductive fibers. Insulating rubber is formed from the above rubber materials.

[0044] The entire rubber brush 60 is elastically deformable. In order to give the brush 60 the required elasticity, the type of rubber material, the amount of rubber compounded in the conductive rubber, and the type of insulating rubber are adjusted.

[0045] Each of the positive electrode brush portion 65, the negative electrode brush portion 66, and the insulating portion 67 is in contact with the outer circumferential surface 50a of the commutator 50 in an elastically deformed state. In other words, the lip portion 63 is in contact with the outer circumferential surface 50a of the commutator 50 in an elastically deformed state. The lip portion 63 is biased toward the outer circumferential surface 50a of the commutator 50 by the restoring force from the elastically deformed state back to its original shape. Therefore, the sliding contact surface 64 of the lip portion 63 is pressed against the outer circumferential surface 50a of the commutator 50 over its entire circumferential direction. Thus, the brush 60 has a sliding contact surface 64 that is pressed against the outer circumferential surface 50a of the commutator 50 over its entire circumferential direction. The rubber elasticity causes the sliding contact surface 64 to press against the outer circumferential surface 50a of the commutator 50, ensuring electrical contact between the positive electrode sliding contact surface 64a of the positive electrode brush portion 65, the negative electrode sliding contact surface 64b of the negative electrode brush portion 66, and the commutator 50.

[0046] The sliding contact surface 64 is pressed against the outer circumferential surface 50a of the commutator 50 by the biasing force of the lip portion 63 directed toward the outer circumferential surface 50a of the commutator 50. The sliding contact surface 64 of the lip portion 63 is pressed toward the commutator 50 from the radially outer side of the rotating shaft 13.

[0047] The brushes 60 of the brushed motor 20 are housed in the motor housing chamber S1. The motor housing chamber S1 is supplied with refrigerant before it is supplied to the compression section 14. The pressure of the refrigerant acts on the lip portion 63. The sliding contact surface 64 of the lip portion 63 is pressed against the outer circumferential surface 50a of the commutator 50 by the pressure of the refrigerant. The pressing of the sliding contact surface 64 against the outer circumferential surface 50a of the commutator 50 ensures electrical contact between the positive electrode sliding contact surface 64a of the positive electrode brush portion 65 and the negative electrode sliding contact surface 64b of the negative electrode brush portion 66 and the commutator 50.

[0048] <Operation of the Embodiment> In the brushed motor 20, when power is supplied from the power supply 70 to the positive brush portion 65 and the negative brush portion 66, current is supplied from the positive brush portion 65 and the negative brush portion 66 to the coil 31 of the armature core 30 via the commutator piece 51 that slides against the positive brush portion 65 and the negative brush portion 66. As a result, the armature core 30 rotates. Consequently, the rotating shaft 13 integrated with the armature core 30 rotates.

[0049] According to the above embodiment, the following effects can be obtained. (1) The positive electrode sliding contact surface 64a of the positive electrode brush portion 65 and the negative electrode sliding contact surface 64b of the negative electrode brush portion 66 of the brush 60 are each made of conductive rubber. Therefore, the contact between the brush 60 and the commutator 50 is contact between metal and conductive rubber. Thus, compared to the case where the positive electrode sliding contact surface 64a and the negative electrode sliding contact surface 64b are all made of metal, the generation of metal wear particles when the commutator 50 slides against the positive electrode sliding contact surface 64a and the negative electrode sliding contact surface 64b can be suppressed.

[0050] (2) The brush 60 is formed in an annular shape from a positive electrode brush portion 65, a negative electrode brush portion 66, and an insulating portion 67. The positive electrode brush portion 65 and the negative electrode brush portion 66 are made of conductive rubber. The insulating portion 67 is made of insulating rubber. Therefore, the entire brush 60 is made of rubber. The brush 60 is also provided with an annular sliding contact surface 64. Due to the rubber elasticity of the entire brush 60, the sliding contact surface 64 is pressed against the outer circumferential surface 50a of the commutator 50 over its entire circumference. Therefore, in the electric compressor 10, the space in the motor housing chamber S1 housing the brushed motor 20 and the space on the opposite side of the brushed motor 20, with the brush 60 in between, can be sealed by the sliding contact surface 64. For example, compared to the case where the brush and the sealing member are provided separately, the dimensions of the electric compressor 10 in the axial direction of the rotating shaft 13 can be reduced.

[0051] (3) The brush 60 is equipped with a lip portion 63. The lip portion 63 is pressed against the outer surface 50a of the commutator 50 by the pressure of the coolant supplied to the motor housing chamber S1. Thus, electrical contact between the commutator 50 and the brush 60 can be ensured.

[0052] (4) Due to the rubber elasticity of the entire brush 60, the sliding contact surface 64 is pressed against the outer circumferential surface 50a of the commutator 50 over its entire circumference. In addition, the coolant in the motor housing chamber S1 presses the sliding contact surface 64 against the outer circumferential surface 50a of the commutator 50 over its entire circumference. Therefore, the rubber elasticity and the coolant allow the positive electrode sliding contact surface 64a of the positive electrode brush portion 65 and the negative electrode sliding contact surface 64b of the negative electrode brush portion 66 to be pressed against the commutator piece 51, thereby ensuring electrical contact between the positive electrode brush portion 65 and the negative electrode brush portion 66 and the commutator 50.

[0053] The embodiment can be implemented with the following modifications. The embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically. ○ As shown in Figure 4, the brush 60 may have a mounting portion 61 and an extension portion 62, but may omit the lip portion 63. In this case, a sliding contact surface 64 is formed on the tip surface of the extension portion 62.

[0054] ○ The sliding contact surface 64 of the brush 60 does not have to be annular. In this case, the positive electrode sliding contact surface 64a of the positive electrode brush portion 65 and the negative electrode sliding contact surface 64b of the negative electrode brush portion 66 slide against the outer circumferential surface 50a of the commutator 50, but the insulating portion 67 may be spaced apart from the outer circumferential surface 50a of the commutator 50. In this configuration, the brush 60 does not need to seal the space between itself and the outer circumferential surface 50a of the commutator 50.

[0055] ○ In the electric compressor 10, it is not necessary for refrigerant to be drawn into the motor housing chamber S1. ○ The brushed motor 20 does not have to be mounted on the electric compressor 10. For example, the brushed motor 20 may be a motor that drives a fan or a motor that drives a pump that pressurizes gas and liquid.

[0056] ○ The brushed motor 20 may be a three-phase AC motor. In this case, the brushed motor 20 is equipped with three commutators 50 and three brushes 60 to match the three phases. ○ The brush 60 may be composed of an extension portion 62 and a lip portion 63, omitting the mounting portion 61.

[0057] ○ The positive electrode brush portion 65, the negative electrode brush portion 66, and the insulating portion 67 may be provided not only on the lip portion 63 but also on the extension portion 62. ○ In the brush 60, the insulating portion 67 may be made of a material other than insulating rubber.

[0058] ○ The positive electrode brush portion 65 may have its entire positive electrode sliding contact surface 64a made of conductive rubber, while the parts other than the positive electrode sliding contact surface 64a may be made of a material other than conductive rubber. Similarly, the negative electrode brush portion 66 may have its entire negative electrode sliding contact surface 64b made of conductive rubber, while the parts other than the negative electrode sliding contact surface 64b may be made of a material other than conductive rubber.

[0059] ○ A portion of the entire surface of the positive electrode sliding contact surface 64a may be formed using conductive rubber, while the remaining portion may be formed using a material other than conductive rubber. Similarly, a portion of the entire surface of the negative electrode sliding contact surface 64b may be formed using conductive rubber, while the remaining portion may be formed using a material other than conductive rubber.

[0060] ○ The inner circumferential surface of the housing 11 may be square or triangular in shape. In this case, the mounting portion 61 will be square or triangular in shape so that it contacts the entire circumferential surface of the inner circumferential surface of the housing 11.

[0061] Next, the technical concepts that can be understood from the above embodiments and alternative examples are described below. (i) A brushed motor in which the brush and the commutator are annular, the brush has an insulating portion interposed between the positive electrode brush portion and the negative electrode brush portion in the circumferential direction of the brush to insulate the positive electrode brush portion and the negative electrode brush portion, the insulating portion is made of insulating rubber, and the brush is pressed against the outer surface of the commutator over its entire circumferential direction and has a sliding contact surface including the positive electrode sliding contact surface and the negative electrode sliding contact surface.

[0062] (b) The brushed motor is mounted on an electric compressor, the electric compressor comprising a rotating shaft to which the commutator is fixed, a compression section that compresses the refrigerant by the rotation of the rotating shaft, and a housing that defines a motor housing chamber for housing the brushed motor, wherein the refrigerant before being compressed by the compression section is drawn into the motor housing chamber through an intake port formed in the housing, and the brush comprises a cylindrical mounting portion that is in contact with the entire circumferential surface of the inner surface of the housing, an annular extension portion that extends from the mounting portion toward the commutator along the radial direction of the rotating shaft, and an annular lip portion that extends from the extension portion toward the commutator and is inclined to approach the compression section as it approaches the commutator from the extension portion, the lip portion having the sliding contact surface.

[0063] (h) An electric compressor comprising a rotating shaft, a compression unit driven by the rotation of the rotating shaft, a brushed motor for rotating the rotating shaft, and a housing for housing the brushed motor, wherein the brushed motor comprises a commutator that rotates integrally with the rotating shaft and brushes that the outer surface of the commutator slides against, the brushes comprising a positive electrode brush portion and a negative electrode brush portion that the commutator slides against, the positive electrode brush portion having a positive electrode sliding contact surface that the commutator slides against, the negative electrode brush portion having a negative electrode sliding contact surface that the commutator slides against, and the positive electrode sliding contact surface and the negative electrode sliding contact surface being formed using conductive rubber. [Explanation of Symbols]

[0064] S1...motor housing, 10...electric compressor, 11...housing, 13...rotating shaft, 14...compression section, 15d...inlet, 20...brushed motor, 50...commutator, 50a...outer surface, 60...brush, 61...mounting section, 62...extension section, 63...lip section, 64...sliding contact surface, 64a...positive electrode sliding contact surface, 64b...negative electrode sliding contact surface, 65...positive electrode brush section, 66...negative electrode brush section, 67...insulating section.

Claims

1. A brush for a brushed motor equipped with a commutator, The commutator comprises a positive electrode brush section and a negative electrode brush section that slide against each other, The positive electrode brush portion has a positive electrode sliding contact surface that the commutator slides against. The negative electrode brush portion has a negative electrode sliding contact surface that the commutator slides against. The positive electrode sliding surface and the negative electrode sliding surface are formed using conductive rubber. The brush and the commutator are annular in shape. The brush is provided with an insulating portion interposed between the positive electrode brush portion and the negative electrode brush portion in the circumferential direction of the brush to insulate the positive electrode brush portion from the negative electrode brush portion, and the insulating portion is formed of insulating rubber. The brush for a brushed motor is characterized in that the brush is pressed against the outer circumferential surface of the commutator over its entire circumference and has a sliding contact surface including the positive electrode sliding contact surface and the negative electrode sliding contact surface.

2. The aforementioned brushed motor is mounted on an electric compressor. The electric compressor comprises a rotating shaft to which the commutator is fixed, a compression unit that compresses the refrigerant by being driven by the rotation of the rotating shaft, and a housing that defines a motor housing chamber for housing the brushed motor, The refrigerant, before being compressed by the compression section, is drawn into the motor housing chamber through an intake port formed in the housing. The brush has a mounting portion that is in contact with the entire circumferential surface of the inner surface of the housing, An annular extension extending from the mounting portion toward the commutator along the radial direction of the rotating shaft, It comprises an annular lip portion that extends from the extension portion toward the commutator and is inclined to approach the compression portion as it approaches the commutator from the extension portion, The brush of the brushed motor according to claim 1, wherein the lip portion is provided with the sliding contact surface.

3. A brushed motor comprising a commutator and brushes with which the commutator slides, The brush comprises a positive electrode brush portion and a negative electrode brush portion that the commutator slides against. The positive electrode sliding contact surface of the positive electrode brush portion and the negative electrode sliding contact surface of the negative electrode brush portion are each formed using conductive rubber. The brush and the commutator are annular in shape. The brush is provided with an insulating portion interposed between the positive electrode brush portion and the negative electrode brush portion in the circumferential direction of the brush to insulate the positive electrode brush portion from the negative electrode brush portion, and the insulating portion is formed of insulating rubber. A brushed motor characterized in that the brush is pressed against the outer surface of the commutator over its entire circumference and has a sliding contact surface including the positive electrode sliding contact surface and the negative electrode sliding contact surface.

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