Shaft grounding apparatus for electric motor and brush unit therefor

Abstract

According to the present invention, provided is a shaft grounding apparatus for an electric motor, the shaft grounding apparatus comprising: a brush unit comprising a discharging brush made of a conductive material, and a brush holder fixing the discharging brush; and a housing accommodating the brush holder, wherein the brush holder comprises: a first holder member in which a brush stopper recess is formed; and a second holder member on which a brush stopper protrusion inserted into the brush stopper recess is formed, and the discharging brush extends to pass between the brush stopper recess and the brush stopper protrusion and is provided with a tip extension extending from the brush holder so that the tip thereof is exposed to the outside of the housing.

Description

Shaft grounding device for electric motor and brush unit therefor

[0001] The present invention relates to a grounding technology for an electric motor, and more particularly, to a shaft grounding device for an electric motor and a brush unit therefor.

[0002] Recently, interest in electric vehicles, which use electrical energy stored in batteries as their power source, has been increasing. Electric vehicles include motors that generate driving force by drawing electrical energy from the battery. Motors used in electric vehicles typically receive three-phase AC power through an inverter. The inverter converts the battery's DC power into three-phase AC power through power module switching. The three-phase voltage is not a perfect sine wave, but rather a square wave, and the sum of the three-phase voltages is not zero. This is called the common-mode voltage. Due to the common-mode voltage applied to the motor coils, a shaft voltage is generated in the rotating shaft due to the parasitic capacitance within the motor. This shaft voltage generates a potential difference between the inner and outer rings of the bearings supporting the rotating shaft, which in turn causes electrical corrosion within the bearings due to discharge mechanisms. This corrosion damages the bearings.

[0003] To reduce the shaft voltage generated in the rotating shaft of an electric motor, a shaft grounding device is used. The shaft grounding device grounds the rotating shaft of the electric motor, thereby eliminating the shaft voltage generated in the rotating shaft. Patent No. 10-2471033 describes a configuration of a shaft grounding device that is installed on the rotating shaft of an electric motor and includes brushes that contact the outer surface of the rotating shaft.

[0004] An object of the present invention is to provide a shaft grounding device for an electric motor with improved grounding performance and a brush unit therefor.

[0005] Another object of the present invention is to provide a shaft grounding device for an electric motor having a structure that is easy to manufacture and a brush unit therefor.

[0006] Another object of the present invention is to provide a shaft grounding device for an electric motor that is easy to install and use in an electric motor and a brush unit therefor.

[0007] In order to achieve the above object of the present invention, according to one aspect of the present invention, there is provided a shaft grounding device for an electric motor, comprising: a brush unit having a discharge brush made of a conductive material and a brush holder for fixing the discharge brush; and a housing for accommodating the brush holder, wherein the brush holder has a first holder member in which a brush engaging groove is formed, and a second holder member in which a brush engaging protrusion inserted into the brush engaging groove is formed, and the discharge brush has an end extension portion that extends so as to pass between the brush engaging groove and the brush engaging protrusion and extends from the brush holder such that an end is exposed to the outside of the housing.

[0008] In order to achieve the above object of the present invention, according to another aspect of the present invention, a brush unit for a shaft grounding device for an electric motor is provided, comprising: a discharge brush made of a conductive material; and a brush holder for fixing the discharge brush, wherein the brush holder has a first holder member in which a brush engaging groove is formed, and a second holder member in which a brush engaging protrusion to be inserted into the brush engaging groove is formed, and the discharge brush extends to pass between the brush engaging groove and the brush engaging protrusion.

[0009] According to the present invention, all of the aforementioned objectives of the present invention can be achieved. Specifically, the discharge brush extends along the radially outer and lower sides, and contacts the grounding means at the radially outer and lower sides, respectively, thereby increasing the contact area, thereby improving grounding performance.

[0010] In addition, a brush unit having a discharge brush, two brush holders for fixing the discharge brush, and a socket in which the brush holders are fixed is assembled by arranging a plurality of brush units along the circumference of the housing, thereby facilitating assembly with a simple structure.

[0011] In addition, the brush holder for fixing the discharge brush and the grounding member for contacting the discharge brush are accommodated in a box-shaped receiving portion of the housing, and the end of the discharge brush is exposed to the outside of the housing, so that it is easy to install and use in various types of electric motors having a rotating shaft.

[0012] FIG. 1 is a perspective view of a shaft grounding device for an electric motor according to a first embodiment of the present invention.

[0013] Fig. 2 is a perspective view of the shaft grounding device for the electric motor of Fig. 1, excluding the cover.

[0014] Fig. 3 is a perspective view of the shaft grounding device for the electric motor of Fig. 1, excluding the housing.

[0015] Fig. 4 is an exploded perspective view of the shaft grounding device for the electric motor of Fig. 1.

[0016] Fig. 5 is a perspective view illustrating the brush unit illustrated in Figs. 2 and 3.

[0017] Fig. 6 is a perspective view of the brush unit of Fig. 5, excluding the socket.

[0018] Fig. 7 is a perspective view showing the discharge brush in an unfolded state as shown in Fig. 6.

[0019] Fig. 8 is a perspective view of a first holder member provided in the brush holder illustrated in Fig. 5.

[0020] Fig. 9 is a perspective view of a second holder member provided in the brush holder illustrated in Fig. 5.

[0021] Figures 10 and 11 are perspective views illustrating the brush unit of Figure 5 excluding the brush holder.

[0022] Figure 12 is a perspective view of the socket illustrated in Figure 5.

[0023] Fig. 13 is a perspective view of the housing illustrated in Fig. 4.

[0024] Fig. 14 is a perspective view of the cover illustrated in Fig. 4.

[0025] Fig. 15 is a cross-sectional view showing the brush unit in Fig. 2 installed in the housing.

[0026] Fig. 16 illustrates a state in which the shaft grounding device for the motor of Fig. 1 is installed in the motor.

[0027] Fig. 17 is a perspective view of a shaft grounding device for an electric motor according to a second embodiment of the present invention.

[0028] Fig. 18 is a perspective view of the shaft grounding device for the motor of Fig. 17, excluding the cover.

[0029] Fig. 19 is a perspective view of the shaft grounding device for the motor of Fig. 17, excluding the housing.

[0030] Fig. 20 is an exploded perspective view of the shaft grounding device for the motor of Fig. 17.

[0031] Fig. 21 is a perspective view illustrating the brush unit illustrated in Figs. 18 and 19.

[0032] Fig. 22 is a perspective view showing the discharge brush in an unfolded state in the state shown in Fig. 21.

[0033] Fig. 23 is a perspective view of a first holder member provided in the brush brush unit of Fig. 21.

[0034] Fig. 24 is a perspective view of a second holder member provided in the brush unit of Fig. 21.

[0035] Fig. 25 is a perspective view showing the state in which the outer grounding member and the bottom grounding member are arranged in the housing in the shaft grounding device for the electric motor of Fig. 17.

[0036] Fig. 26 is a cross-sectional view showing a state in which a brush unit is installed in the shaft grounding device for the electric motor of Fig. 17.

[0037] Fig. 27 is a perspective view of a shaft grounding device for an electric motor according to a third embodiment of the present invention.

[0038] Fig. 28 is a perspective view of the shaft grounding device for the motor of Fig. 27, excluding the cover.

[0039] Fig. 29 is an exploded perspective view of the shaft grounding device for the motor of Fig. 27.

[0040] Fig. 30 is a cross-sectional view of the shaft grounding device for the electric motor of Fig. 27.

[0041] Figure 31 illustrates a state in which the shaft grounding device for the motor of Figure 27 is installed in the motor.

[0042] Fig. 32 is a cross-sectional view of a shaft grounding device for an electric motor according to a fourth embodiment of the present invention.

[0043] Hereinafter, the configuration and operation of an embodiment of the present invention will be described in detail with reference to the drawings.

[0044] In the present invention, grounding also means removing static electricity from a grounding object along with general grounding.

[0045] Referring to FIGS. 1, 2, 3 and 4, a shaft grounding device (100) for an electric motor according to a first embodiment of the present invention includes a plurality of brush units (105), a grounding member (160) for grounding the plurality of brush units (105), a housing (170) that houses the plurality of brush units (105) and the grounding member (160) therein, a cover (180) covering the housing (170), and a grounding line (190) coupled to the grounding member (160). For convenience of explanation, a central axis (X) extending in a straight line is introduced.

[0046] A plurality of brush units (105) are accommodated in a housing (170) so as to be arranged in sequence along a circumferential direction with respect to a central axis (X). FIG. 5 illustrates a brush unit (105) in a perspective view. Referring to FIGS. 2, 4, and 5, each of the plurality of brush units (105) includes a discharge brush (110), two brush holders (120) coupled to the discharge brush (110), and a socket (150) for fixing the two brush holders (120).

[0047] The discharge brush (110) is described as a carbon material in the shape of a band, and is an electrically conductive fiber-shaped carbon fiber material. However, it may alternatively be a metal fiber, which also falls within the scope of the present invention. In the present embodiment, the carbon material includes a single carbon material such as carbon fiber and a carbon composite material. The discharge brush (110) is formed by gathering electrically conductive fibers to form a band shape. The discharge brush (110) is fixed to two brush holders (120). FIG. 6 illustrates the brush unit of FIG. 5 excluding the socket (150). Referring to FIGS. 4, 5, and 6, one discharge brush (110) has two end extensions (112) formed by protruding from each of the two brush holders (120), and an intermediate extension (115) formed by extending between the two brush holders (120).

[0048] Each of the two end extensions (112) is formed by protruding from each of the two brush holders (120). Each of the two end extensions (112) extends radially inwardly from each of the two brush holders (120) with respect to a central axis (X). The belt surfaces of the two end extensions (112) are generally perpendicular to the central axis (X). The ends of each of the two end extensions (112) protrude from the housing (170) and the cover (180) and are exposed to the outside.

[0049] The intermediate extension (115) is formed by extending between two brush holders (120). The intermediate extension (115) is connected to the socket (150) in a manner that wraps around the socket (150). The intermediate extension (115) has two outer extension sections (116), two lower extension sections (117), and a connecting section (118).

[0050] Each of the two outer extension sections (116) is positioned radially outward with respect to each of the two brush holders (120). The outer extension section (116) is formed by extending the discharge brush (110) after it is bent downward with respect to the brush holder (120). The belt surface of the outer extension section (116) is formed to be generally perpendicular to the radial direction and thus makes surface contact with the grounding member (160).

[0051] Each of the two lower extension sections (117) is positioned below each of the two brush holders (120). The lower extension section (117) is formed by extending and bending radially inward from the lower end of the outer extension section (116). The belt surface of the lower extension section (117) is formed to be generally perpendicular to the central axis (X) and thus comes into surface contact with the grounding member (160). The two lower extension sections (117) are connected by a connecting section (118).

[0052] The connecting section (118) connects the radially inner ends of each of the two lower extension sections (117).

[0053] A state as illustrated in FIG. 6 can be achieved by combining two brush holders (120) to the discharge brush (110) while the entire discharge brush (110) is flat as illustrated in FIG. 7, and then folding the middle extension portion (115) of the discharge brush (110) into the shape illustrated. In this embodiment, it is described that there are 9 discharge brushes (110) and a total of 18 end extension portions (112), but the present invention is not limited thereto, and the number of discharge brushes (110) may be 8 or less or 10 or more, which also falls within the scope of the present invention.

[0054] Referring to Fig. 2, two brush holders (120) provided in one brush unit (105) are arranged in sequence along the circumferential direction. Referring to Figs. 2, 4, 5 and 6, two brush holders (120) are coupled to one discharge brush (110). In this embodiment, the brush holder (120) is described as being an electrically non-conductive resin injection molded product. The brush holder (120) is seated in a socket (150) to fix the position of the discharge brush (110). The brush holder (120) has a first holder member (130) and a second holder member (140). The first holder member (130) and the second holder member (140) are coupled to the discharge brush (110) while making surface contact with the discharge brush (110) with the discharge brush (110) interposed therebetween. The first holder member (130) and the second holder member (140) press the discharge brush (110).

[0055] Fig. 8 illustrates a first holder member (130) in a perspective view. Referring to Fig. 8, a brush engaging groove (132) is formed on a path through which a discharge brush (110) passes in the first holder member (130). The brush engaging groove (132) extends along the width direction of the discharge brush (110), so that the entire width direction of a longitudinal section of the discharge brush (110) is inserted into the brush engaging groove (132). The first holder member (130) has engaging protrusions (134) positioned on both sides of the path through which the discharge brush (110) passes. The second holder member (140) is engaged with the first holder member (130) by the engaging protrusions (134).

[0056] FIG. 9 illustrates a perspective view of a second holder member (140). Referring to FIG. 9, the second holder member (140) has a brush catching protrusion (142) that is inserted into a brush catching groove (132) formed in the first holder member (130). As illustrated in FIG. 15, the brush catching protrusion (142) is inserted into the brush catching groove (132) formed in the first holder member (130) to fix the discharge brush (110) passing between the first holder member (130) and the second holder member (140). Referring to FIG. 9, the second holder member (140) has engaging grooves (144) formed on each of both sides with the brush catching groove (132) interposed therebetween. The engaging grooves (144) are formed on each of two wing portions (146) in the form of elastically deformable walls. The two wing parts (146) face each other with a joining groove (144) therebetween. The joining projection (134) of the first holder member (130) is fitted into the joining groove (144) so ​​that the first holder member (130) and the second holder member (140) are joined. The first holder member (130) is entirely inserted into the space formed between the two wing parts (146) of the second holder member (140). As illustrated in FIG. 5, the brush holder (120) is seated in the socket (150) so that the first holder member (130) is positioned lower than the second holder member (140).

[0057] Referring to Fig. 5, a socket (150) secures two brush holders (120). The two brush holders (120) are seated in the socket (150). In this embodiment, the socket (150) is described as being an electrically non-conductive resin injection molded product. Figs. 10, 11, and 12 are drawings of the socket (150). Referring to Figs. 10, 11, and 12, the socket (150) has a base portion (151), an extension plate portion (156) extending radially inward from the base portion (151), and a support portion (158) connected to an end of the extension plate portion (156).

[0058] The base (151) is generally block-shaped and has two seating grooves (152) spaced apart from each other along the circumference. A brush holder (120) is seated in each of the two seating grooves (152). The first brush engaging groove (132) of the brush holder (120) is positioned closer to the bottom of the seating groove (152) than the brush engaging protrusion (142). Two outer extension sections (116) provided on the discharge brush (110) are positioned on the radially outer outer side of the base (151).

[0059] The extension plate (156) is generally formed in a plate shape and extends radially inward from the bottom of the base (151). A support (158) is integrally connected to the radially inner end of the extension plate (156). Each of the two lower extension sections (117) provided on the discharge brush (110) is located below the base (151) and the extension plate (156), and the connection section (118) provided on the discharge brush (110) is located above the extension plate (156). The extension plate (156) is formed so that both sides are inclined with respect to the radial direction so that the width becomes narrower toward the radially inner end, so that the connection section (118) provided on the discharge brush (110) and the two lower extension sections (117) are naturally bent and connected as shown.

[0060] The support portion (158) is connected to the end of the extension plate portion (156) and formed integrally. The support portion (158) is formed by protruding from the extension plate portion (156). The support portion (158) stably supports the brush holder (120) by contacting the radially inner end portions of each of the two brush holders (120) that are seated in the seating groove (152).

[0061] Although the above embodiment describes the brush unit (105) as having two brush holders (120), it may alternatively have three or more brush holders (120), and this also falls within the scope of the present invention. When the brush unit (105) has three or more brush holders (120), the intermediate extension portion (115) may be formed to extend radially outward or downward from the brush holder (120) in various ways. In addition, the brush unit (105) may have only one brush holder (120), and this also falls within the scope of the present invention. When the brush unit (105) has only one brush holder (120), the intermediate extension portion (115) may come into contact with the grounding member (160) in a form in which the middle is cut off.

[0062] Referring to FIGS. 2, 3, 4, and 15, a grounding member (160) is made of an electrically conductive material and is accommodated in a housing (170) to ground each of the discharge brushes (110) provided on each of the plurality of brush units (105). The grounding member (160) constitutes a grounding means according to the present invention. The grounding member (160) has a wall-shaped outer grounding portion (161) that surrounds the plurality of brush units (105) from the radial outside, a plurality of bottom grounding portions (164) that are formed by protruding radially inward from the outer grounding portion (161), a plurality of grounding wings (166) that are formed by extending radially outward from the outer grounding portion (161), and a fixed wing (168) that is formed by extending radially inward from the outer grounding portion (161). The grounding member (160) can be manufactured by cutting and bending a plate material.

[0063] The outer grounding portion (161) is a wall-shaped portion that surrounds a plurality of brush units (105) from the radial outside. The outer grounding portion (161) has a plurality of unit grounding sections (162) arranged in sequence along the circumferential direction. Each of the plurality of unit grounding sections (162) is substantially perpendicular to the radial direction and extends in a straight line along the circumferential direction. The number of unit grounding sections (162) is the same as the number of brush units (105). That is, in the present embodiment, the number of unit grounding sections (162) is nine, which is the same as the number of brush units (105). Two outer extension sections (116) provided on the inner surface of the unit grounding section (162) of one brush unit (105) are in contact with each other and electrically connected. A plurality of floor grounding sections (164), a plurality of grounding vanes (166), and a fixed vane (168) are integrally connected to the outer grounding portion (161).

[0064] Each of the plurality of floor grounding portions (164) is formed by protruding radially inward from the lower end of each of the plurality of unit grounding sections (162) of the outer circumferential grounding portion (161). Each of the plurality of floor grounding portions (164) is in the shape of a flat plate and can be formed by being bent from the outer circumferential grounding portion (161). Two lower extension sections (117) provided on one brush unit (105) are electrically connected by making contact with the upper surface of each of the plurality of floor grounding portions (164).

[0065] Each of the plurality of grounding wings (166) is formed to extend radially outward from the lower end of the outer circumferential grounding portion (161). In the present embodiment, there are three grounding wings (166), which are arranged at equal intervals along the circumferential direction. Each of the plurality of grounding wings (166) is positioned between two adjacent bottom grounding portions (164). Each of the plurality of grounding wings (166) is positioned at a vertex of the outer circumferential grounding portion (161) forming a polygon. A through hole (167) is formed in each of the plurality of grounding wings (166). The through hole (167) is a hole through which a screw nail that connects the shaft grounding device (100) for an electric motor to the electric motor passes.

[0066] The fixed wing (168) is formed by extending radially inward from the upper end of the outer circumferential grounding portion (161). The fixed wing (168) is located between two adjacent bottom grounding portions (164). The fixed wing (168) is located at the vertex of the outer circumferential grounding portion (161) forming a polygon. A through hole (169) is formed in the fixed wing (168). The through hole (169) is a hole through which a screw nail that fixes the grounding member (160) to the housing (170) passes. As shown in the drawing, a grounding line (190) is connected to the fixed wing (168) by the screw nail, so that the grounding member (160) and the grounding line (190) can be electrically connected.

[0067] In the above embodiment, the grounding member (160) is described as being one, but it may be configured in a different way by being divided into multiple members arranged along the circumference, and this also falls within the scope of the present invention.

[0068] Referring to Fig. 2, a housing (170) accommodates a plurality of brush units (105) and a grounding member (160) therein. In this embodiment, the housing (170) is a resin injection molded product and is made of an electrically non-conductive material. Fig. 13 illustrates a perspective view of the housing (170). Referring to Figs. 1, 2, 4, 13, and 15, the housing (170) includes a ring-shaped base plate (171), an outer wall (173) formed by protruding from the outer periphery of the base plate (171), an inner wall (175) formed by protruding from the inner periphery of the base plate (171), a plurality of support wall portions (177) formed by protruding from the base plate (171), and a plurality of coupling wings (178) formed by protruding radially outward from the outer wall (173). A cover (180) is combined with the housing (170), so that a plurality of brush units (105) and a grounding member (160) accommodated inside are fixed and protected.

[0069] The base plate (171) is generally ring-shaped with the central axis (X) as the center, and a circular through hole (172) with the central axis (X) as the center is formed in the center of the base plate (171). The inner periphery of the base plate (171) is positioned radially outer than the radially inner end of the end extension (112) formed on the discharge brush (110). That is, the end extension (112) of the discharge brush (110) protrudes further inward than the inner periphery of the base plate (171).

[0070] The outer wall (173) protrudes from the outer periphery of the base plate (171) and forms a generally right angle with the base plate (171). The height of the outer wall (173) corresponds to the thickness of the brush unit (105). The outer wall (173) is formed with a plurality of side openings (174a) that communicate with each of the plurality of coupling wings (178) and a grounding line passage (174b) through which the grounding wire (190) passes. Through the plurality of side openings (174a), each of the plurality of grounding wings (166) provided on the grounding member (160) protrudes radially outward from the outer wall (173) and is exposed, so that the grounding wing (166) is accommodated inside the corresponding coupling wing (178). The grounding wire (190) coupled to the grounding member (160) can be extended to the outside through the grounding line passage (174b).

[0071] The inner wall (175) is formed by protruding from the inner periphery of the base plate (171) in the same direction as the outer wall (173). On the outer surface of the inner wall (175) facing the outer wall (173), a plurality of seating grooves (176) are formed along the circumferential direction, in which the radial ends of the support portions (158) of the sockets (150) provided in each of the plurality of brush units (105) are seated. In the present embodiment, the number of seating grooves (176) is 9, the same as the number of brush units (105).

[0072] A plurality of support wall portions (177) are formed by protruding from the base plate (171) and are arranged in sequence along the circumferential direction. The plurality of support wall portions (177) are positioned adjacent to the outer wall (173) between the outer wall (173) and the inner wall (175). The support wall portion (177) has a flat wall shape that is generally perpendicular to the radial direction. A unit grounding section (162) formed on the outer grounding section (161) of the grounding member (160) is supported by making surface contact with the inner wall surface in the radial direction of the support wall portion (177). The number of support wall portions (177) is 9, which is the same as the number of unit grounding sections (162).

[0073] Each of the plurality of coupling wings (178) is formed to protrude radially outward from the outer wall (173) and is arranged at equal intervals in sequence along the circumferential direction. Each of the plurality of coupling wings (178) communicates with the inner space of the outer wall (173) through a side opening (174a) formed in the outer wall (173). The grounding wing (166) of the grounding member (160) is mounted on the coupling wing (178). A through hole (179) is formed in the coupling wing (178). The through hole (179) is a hole through which a screw nail that connects the shaft grounding device (100) for the electric motor to the electric motor passes.

[0074] Referring to Fig. 1, the cover (180) covers and closes the housing (170). The cover (180) is connected to the housing (170) by a screw or a separately formed hook structure. In the present embodiment, the cover (180) is a resin injection molded product and is made of an electrically non-conductive material. Fig. 14 illustrates the cover (180) in a perspective view. Referring to Figs. 1, 3, 4, and 14, the cover (180) has a ring-shaped cover plate portion (181), a plurality of closing portions (185) formed by protruding from the outer periphery of the cover plate portion (181), and a protrusion (187) formed by protruding from the outer periphery of the cover plate portion (181).

[0075] The cover plate (181) is generally in the shape of a ring centered on the central axis (X), and a circular through hole (182) centered on the central axis (X) is formed in the center of the cover plate (181). The size of the through hole (182) is smaller than the size of the through hole (172) formed in the base plate (171) of the housing (170) and larger than the diameter formed by the end extensions (112).

[0076] A plurality of closing portions (185) are formed by protruding from the outer periphery of the cover plate portion (181). The plurality of closing portions (185) are arranged at equal intervals in sequence along the circumferential direction. In the present embodiment, the number of closing portions (185) corresponds to the number of side openings (174a) formed in the housing (170). Each of the plurality of closing portions (185) blocks a side opening (174a) formed in the housing (170).

[0077] The protrusion (187) is formed by protruding from the outer periphery of the cover plate (181). The protrusion (187) blocks the upper end of the grounding line passage (174b) formed in the housing (170).

[0078] The ground wire (190) is electrically connected to the grounding member (160) by being connected to the fixed wing (168) provided on the grounding member (160) by screws or welding. The ground wire (190) is extended to the outside of the housing (170) through the grounding wire passage (174b) formed on the housing (170).

[0079] Fig. 16 illustrates a state in which a shaft grounding device (100) for an electric motor is installed on an electric motor (M). Referring to Fig. 16, the shaft grounding device (100) for an electric motor is coupled to a grounded electric motor (M) so that the shaft (S) of the electric motor (M) passes through a through hole formed in the center of the shaft grounding device (100) for an electric motor. The radially inner end of the end extension (112) provided on each of the plurality of discharge brushes (110 in Fig. 5) provided on the shaft grounding device (100) for an electric motor is electrically connected by contacting the outer surface of the shaft (S) provided on the electric motor (M). The shaft grounding device (100) for an electric motor is fastened to the grounded electric motor (M) by screw nails on a plurality of coupling wings (178) provided on a housing (170). The shaft grounding device (100) for an electric motor is grounded by an electrically conductive screw nail that contacts a grounding wing (166) provided on a grounding member (160 in FIG. 4) that contacts a discharge brush (110 in FIG. 5) and fastens the shaft grounding device (100) for an electric motor to the electric motor (M). Additionally, the shaft grounding device (100) for an electric motor is grounded by connecting a grounding wire (190) to an external grounding terminal. The electric motor (M) is a rotary motor in which a shaft (S) rotates along an axis or a linear motor in which a shaft (S) reciprocates linearly along an axial direction.

[0080] Referring to FIGS. 17, 18, 19, and 20, a shaft grounding device (200) for an electric motor according to a second embodiment of the present invention includes a plurality of brush units (205), a unit mounting member (250) on which the plurality of brush units (205) are mounted, an outer grounding member (260) for grounding the plurality of brush units (205), a floor grounding member (265) for grounding the plurality of brush units (205), a housing (270) that houses the plurality of brush units (205), the unit mounting member (250), the outer grounding member (260), and the floor grounding member (265) therein, a cover (280) for covering the housing (270), and a grounding line (290) coupled to the floor grounding member (265). For convenience of explanation, a central axis (X) extending in a straight line is introduced.

[0081] A plurality of brush units (205) are accommodated in a housing (270) while being mounted on a unit mounting member (250) so as to be arranged in a circumferential direction in sequence with respect to a central axis (X). FIG. 21 illustrates a brush unit (205) in a perspective view. Referring to FIGS. 18, 20, and 21, each of the plurality of brush units (205) has a discharge brush (210) and two brush holders (220) coupled to the discharge brush (210).

[0082] The discharge brush (210) is described as a carbon material in the shape of a band, and is an electrically conductive fiber-shaped carbon fiber material. However, it may alternatively be a metal fiber, which also falls within the scope of the present invention. In the present embodiment, the carbon material includes a single carbon material such as carbon fiber and a carbon composite material. The discharge brush (210) is formed by gathering electrically conductive material fibers to form a band shape. The discharge brush (210) is fixed to two brush holders (220). One discharge brush (210) has two end extensions (212) formed by protruding from each of the two brush holders (220), and a middle extension (215) formed by extending between the two brush holders (220).

[0083] Each of the two end extensions (212) is formed by protruding from each of the two brush holders (220). Each of the two end extensions (212) extends radially inwardly from each of the two brush holders (220) with respect to the central axis (X). The belt surfaces of the two end extensions (212) are generally perpendicular to the central axis (X). The ends of each of the two end extensions (212) protrude from the housing (270) and the cover (280) and are exposed to the outside.

[0084] The intermediate extension (215) is formed by extending between two brush holders (220). The intermediate extension (215) has two outer extension sections (216) and a lower extension section (217) connecting the two outer extension sections (216).

[0085] Each of the two outer extension sections (216) is positioned radially outward with respect to each of the two brush holders (220). The outer extension section (216) is formed by extending the discharge brush (210) after it is bent downward with respect to the brush holder (220). The belt surface of the outer extension section (216) is formed to be generally perpendicular to the radial direction and thus makes surface contact with the outer circumferential grounding member (260). A lower extension section (217) is connected to the lower end of each of the two outer extension sections (216).

[0086] The lower extension section (217) is located below the unit mounting member (250). The lower extension section (217) is formed by extending and bending radially inward from the lower end of the outer extension section (216). The longitudinal ends of the lower extension section (217) are connected to the lower ends of each of the two outer extension sections (216). The belt surface of the lower extension section (217) is formed to be generally perpendicular to the central axis (X) and thus makes surface contact with the floor grounding member (265).

[0087] A state as illustrated in Fig. 21 can be achieved by, as illustrated in Fig. 22, combining two brush holders (220) with the discharge brush (210) in a flat state throughout, and then folding the middle extension portion (215) of the discharge brush (210) into the shape as illustrated. In this embodiment, it is described that there are six discharge brushes (210) and twelve end extension portions (212), but the present invention is not limited thereto, and the number of discharge brushes (110) may be five or less or seven or more, which also falls within the scope of the present invention.

[0088] Referring to Fig. 18, two brush holders (220) provided in one brush unit (205) are arranged in sequence along the circumferential direction. Referring to Figs. 18, 20, and 21, two brush holders (220) are coupled to one discharge brush (210). The brush holder (220) is made of an electrically conductive or electrically non-conductive material. The brush holder (220) is mounted on a unit mounting member (250) to fix the position of the discharge brush (210). The brush holder (220) has a first holder member (230) and a second holder member (240). The first holder member (230) and the second holder member (240) are coupled to the discharge brush (210) while making surface contact with the discharge brush (210) with the discharge brush (210) interposed therebetween. The first holder member (230) and the second holder member (240) press the discharge brush (110).

[0089] Fig. 23 illustrates a first holder member (230) in a perspective view. Referring to Fig. 23, a brush engaging groove (232) is formed on a path through which a discharge brush (210) passes in the first holder member (230). The brush engaging groove (232) extends along the width direction of the discharge brush (210), so that the entire width direction of a longitudinal section of the discharge brush (210) is inserted into the brush engaging groove (232). The first holder member (230) has engaging grooves (234) positioned on both sides of the path through which the discharge brush (210) passes. The second holder unit (240) is engaged with the first holder unit (230) by the engaging grooves (234). The engaging grooves (234) are formed on each of two elastically deformable wing portions (236). The two wing parts (236) face each other with the brush catch groove (232) between them. The entire second holder member (240) is inserted into the space formed between the two wing parts (236).

[0090] Fig. 24 illustrates a perspective view of a second holder member (240). Referring to Fig. 24, the second holder member (240) has a brush engaging projection (242) that is inserted into a brush engaging groove (232) formed in the first holder member (230). As illustrated in Fig. 26, the brush engaging projection (232) is inserted into the brush engaging groove (232) formed in the first holder member (230) to fix the discharge brush (210) passing between the first holder member (230) and the second holder member (240). Referring to Fig. 24, the second holder member (240) has engaging projections (243) formed on both sides with the brush engaging groove (232) interposed therebetween. The first holder unit (230) and the second holder unit (240) are coupled by the coupling protrusion (243) being fitted into the coupling groove (234) of the first holder unit (230). The second holder member (240) is entirely inserted into the space formed between the two wing parts (236) of the first holder member (230). As illustrated in Fig. 26, the brush holder (220) is mounted on the unit mounting member (250) so that the first holder member (230) is positioned lower than the second holder member (240).

[0091] Although the above embodiment describes the brush unit (205) as having two brush holders (220), it may alternatively have three or more brush holders (220), and this also falls within the scope of the present invention. In the case where the brush unit (205) has three or more brush holders (220), the intermediate extension portion (215) may be formed to extend radially outward or downward from the brush holder (120) in various ways. In addition, the brush unit (205) may have only one brush holder (220), and this also falls within the scope of the present invention. In the case where the brush unit (205) has only one brush holder (220), the intermediate extension portion (115) may be in contact with the grounding means (260) in a form in which the middle is cut off.

[0092] Referring to FIGS. 20 and 26, the unit mounting member (250) mounts a plurality of brush units (205). The unit mounting member (250) has a ring shape centered on a central axis (X). The unit mounting member (250) is accommodated inside a housing (270) and is positioned to face a cover (280). In the present embodiment, the unit mounting member (250) is described as being a resin injection molded product made of an electrically non-conductive material. A circular through hole (251) centered on the central axis (X) is formed in the center of the unit mounting member (250). An end extension (212) of a discharge brush (210) protrudes further inward than the inner circumference of the unit mounting member (250). A plurality of holder mounting grooves (252) are formed in the unit mounting member (250) and are sequentially arranged along the circumferential direction. One brush holder (220) is mounted on each of the plurality of holder mounting grooves (252).

[0093] Referring to FIGS. 19, 20, 25, and 26, the outer grounding member (260) is made of an electrically conductive material and is accommodated in a housing (270) to ground each of the discharge brushes (210) provided on each of the plurality of brush units (205). The outer grounding member (260) surrounds the plurality of brush units (205) from the radial outside. The outer grounding member (260) has a generally ring shape centered on a central axis (X) and has an inner circumferential surface (261) facing radially inward and an outer circumferential surface (262) facing radially outward. The inner circumferential surface (261) of the outer grounding member (260) is in surface contact with the outer extension sections (216) of the discharge brushes (210) provided on the plurality of brush units (205). The outer circumferential surface (262) of the outer grounding member (260) is in close contact with the housing (270). The outer circumferential grounding member (260) can be fixed by having its outer surface (262) adhered to the housing (270). The outer circumferential grounding member (260) has a protrusion (263) formed by protruding radially inward. The protrusion (263) is received in an outer circumferential groove (254) formed on the outer periphery of the unit mounting member (250). The outer circumferential grounding member (260) is electrically connected to the bottom grounding member (265) by contacting it. In the above embodiment, the outer circumferential grounding member (260) is described as being one, but a plurality of pieces may be configured by being arranged in a circumferential direction in a divided form, and this also falls within the scope of the present invention.

[0094] The floor grounding member (265) grounds the plurality of brush units (205) together with the outer grounding member (260). Referring to FIGS. 19, 20, 25, and 26, the floor grounding member (265) is made of an electrically conductive material and is accommodated in a housing (270) to ground each of the discharge brushes (210) provided in each of the plurality of brush units (205). The floor grounding member (265) has a generally ring-shaped brush contact portion (266), an extension portion (267) extending from the brush contact portion (266), and a grounding line connecting portion (268) located at the end of the extension portion (267). The floor grounding member (265), together with the outer grounding member (260), constitutes a grounding means according to the present invention. In the above embodiment, the floor grounding member (265) is described as being one, but it may be configured in a different way by being divided into multiple members arranged along the circumference, and this also falls within the scope of the present invention.

[0095] The brush contact portion (266) is a generally plate-shaped ring centered on the central axis (X) and makes surface contact with the lower extension section (217) of the discharge brush (210) provided in the plurality of brush units (205). The brush contact portion (266) can be fixed by being bonded to the housing (270). An extension portion (267) is located on the outer periphery of the brush contact portion (266).

[0096] The extension (267) extends in a band shape from the outer periphery of the brush contact portion (266). The extension (267) is generally perpendicular to the brush contact portion (266). The extension (267) passes between the unit mounting member (250) and the protrusion (263) provided on the outer periphery grounding member (260) in the outer periphery groove (254) formed on the unit mounting member (250). The extension (267) is electrically connected to the outer periphery grounding member (260) by making surface contact with it. A grounding line connecting portion (268) is located at the end of the extension (267).

[0097] The grounding wire connection portion (268) is located at the end of the extension portion (267). The grounding wire connection portion (268) is formed by being bent from the end of the extension portion (267) and extending radially inward. The grounding wire connection portion (268) covers the unit mounting member (250) from above. A through hole (269) is formed in the grounding wire connection portion (268). The through hole (269) is a hole through which a screw nail connecting the grounding wire (290) to the floor grounding member (260) passes. The screw nail connecting the grounding wire (290) to the floor grounding member (260) can be screw-connected to the unit mounting member (250). The floor grounding member (260) is electrically connected to the grounding wire (290) at the grounding wire connection portion (268).

[0098] The housing (270) accommodates a plurality of brush units (205), a unit mounting member (250), an outer periphery grounding member (260), and a floor grounding member (265) therein. In the present embodiment, the housing (270) is a resin injection molded product made of an electrically non-conductive material. Referring to FIGS. 20, 25, and 26, the housing (270) has a ring-shaped base plate (271) and an outer periphery wall (273) extending from the outer periphery of the base plate (271). A cover (280) is coupled to the housing (270), so that the plurality of brush units (205) accommodated therein are fixed and protected.

[0099] The base plate (271) is generally ring-shaped with the central axis (X) as the center, and a circular through hole (272) with the central axis (X) as the center is formed in the center of the base plate (271). The through hole (272) is not smaller than the through hole (251) formed in the unit mounting member (250), but in this embodiment, it is described as being larger. The inner circumference of the base plate (271) is positioned radially outerward from the radially inner end of the end extension (212) formed in the discharge brush (210). That is, the end extension (212) of the discharge brush (210) protrudes further inward than the inner circumference of the base plate (271). The brush contact portion (266) of the floor grounding member (265) is fixed by making close surface contact with the base plate (271).

[0100] The outer wall (273) protrudes from the outer periphery of the base plate (271) and forms a generally right angle with the base plate (271). A grounding line passageway (274) through which a grounding line (290) passes is formed in the outer wall (273). The grounding line (290) connected to the floor grounding member (265) can be extended to the outside through the grounding line passageway (274). The outer grounding member (260) is fixed by making close contact with the inner surface of the outer wall (273).

[0101] Referring to Fig. 17, a cover (280) covers and closes the housing (270). In this embodiment, the cover (280) is an electrically non-conductive resin injection molded product. Referring to Figs. 17, 19, 20, and 26, the cover (280) has a generally ring shape centered on a central axis (X). A circular through hole (282) centered on the central axis (X) is formed in the center of the cover (280). The size of the through hole (282) is formed smaller than the through hole (251) formed in the unit mounting member (250) and larger than the diameter formed by the end extensions (212). The cover (280) is formed with upper mounting grooves (283) in which a plurality of brush holders (220) are respectively mounted. Accordingly, the lower part of the brush holder (220) is seated in the holder seat groove (252) formed in the unit seat member (250), and the upper part of the brush holder (220) is seated in the upper seat groove (283) formed in the cover (280).

[0102] The ground wire (290) is connected to the ground wire connecting portion (268) provided in the floor grounding member (265) by screwing or electric welding, and is electrically connected to the floor grounding member (265). Since the floor grounding member (265) is in contact with the outer grounding member (260), the ground wire is also electrically connected to the outer grounding member (260). The ground wire (290) is extended to the outside of the housing (270) through the ground wire passage (274) formed in the housing (270).

[0103] Referring to FIGS. 27, 28, and 29, a shaft grounding device (300) for an electric motor according to a third embodiment of the present invention includes brush units (105), a grounding member (360) for grounding the brush unit (105), a housing (370) that houses the brush unit (105) and the grounding member (360) therein, a cover (380) for covering the housing (370), and a grounding wire (390) coupled to the grounding member (360).

[0104] The brush unit (105) is accommodated in the housing (170). The brush unit (105) is the same as the brush unit (105) described above with reference to FIGS. 5 to 12. Each of the two end extensions (112) is formed by protruding from each of the two brush holders (120). Each of the two end extensions (112) extends in the same direction from each of the two brush holders (120) and is arranged parallel. The belt surfaces of the two end extensions (112) are generally on the same plane. The two end extensions (112) are brought closer to each other as they go toward the ends. The ends of each of the two end extensions (112) protrude from the housing (170) and the cover (180) and are exposed to the outside. The outer extension section (116) is in surface contact with the grounding member (360). The lower extension section (117) extends generally parallel to the end extension section (112) and makes surface contact with the grounding member (360). The brush unit (105) may have only one brush holder (120) like the brush unit (105) described above with reference to FIGS. 5 to 12, and this also falls within the scope of the present invention.

[0105] Referring to FIGS. 28, 29, and 30, a grounding member (360) is housed in a housing (370) as an electrically conductive material and grounds a discharge brush (110) provided in a brush unit (105). The grounding member (360) has a plate-shaped bottom grounding portion (361), a side grounding portion (364) formed by extending upward from an outer end of the bottom grounding portion (361), and two grounding wings (366) formed by extending from each of both ends of the bottom grounding portion (361). The grounding member (360) can be manufactured by cutting and bending a plate material. In this embodiment, the grounding member (360) is described as being formed as a single piece of a bottom grounding portion (361) and a side grounding portion (364), but, unlike this, the bottom grounding portion (361) and the side grounding portion (364) may be formed as separate, non-integral parts, and this also falls within the scope of the present invention.

[0106] The bottom grounding portion (361) is a flat plate, is accommodated in the housing (370) and is placed on the bottom of the housing (370). Two lower extension sections (117) formed on the discharge brush (110) provided in the brush unit (105) on the upper surface of the bottom grounding portion (361) are electrically connected by making surface contact. The side grounding portion (364) and two grounding wings (366) are integrally connected to the bottom grounding portion (361).

[0107] The side grounding portion (364) is formed in the shape of a wall by extending upward from the outer end of the floor grounding portion (361). Two outer extension sections (116) formed on the discharge brush (110) provided in the brush unit (105) on the inner surface of the side grounding portion (364) connected to the upper surface of the floor grounding portion (361) are electrically connected by making surface contact.

[0108] Two grounding wings (366) are formed by extending from each end of the bottom grounding portion (361). That is, the two grounding wings (366) are positioned with the bottom grounding portion (361) therebetween. The bottom grounding portion (361) is a flat plate that forms the same plane as the bottom grounding portion (361). A through hole (367) is formed in each of the two grounding wings (366). The through hole (367) is a hole through which a screw nail that connects the shaft grounding device (300) for the motor to the motor passes.

[0109] Referring to Fig. 28, the housing (370) accommodates the brush unit (105) and the grounding member (360) therein. In the present embodiment, the housing (370) is a resin injection molded product made of an electrically non-conductive material. Referring to Figs. 28, 29, and 30, the housing (370) has a receiving portion (370a) and two connecting wings (377) formed by protruding from the receiving portion (370a) on both sides.

[0110] The receiving portion (370a) is generally in the shape of a square box and provides a receiving space (379) therein. The receiving portion (370a) has a square-shaped bottom plate (371) and side walls (373) that protrude from the edge of the bottom plate (371). The bottom plate (371) and the side walls (373) form a receiving space (379) in which the brush unit (105) and the bottom grounding portion (361) and the side grounding portion (364) of the grounding member (360) are received. The open upper end of the receiving space (379) in the receiving portion (370a) is closed by a cover (380), so that the brush unit (105) and the grounding member (360) received therein are fixed and protected.

[0111] The floor plate (371) is generally a square plate, and the upper surface of the floor plate (371) forms the bottom surface of the receiving space (379) on which the bottom grounding portion (361) of the grounding member (360) is placed. The bottom grounding portion (361) of the grounding member (360) can be fixed by being adhered to the bottom surface of the floor plate (371).

[0112] The side wall (373) protrudes and extends from the edge of the floor plate (371) to form a generally right angle with the floor plate (371). The side wall (373) has a flat front wall portion (373a), a flat rear wall portion (373b) facing the front wall portion (373a), and two connecting wall portions (373c) connecting the front wall portion (373a) and the rear wall portion (373b) and facing each other.

[0113] The front wall (373a) is formed in a flat wall shape and is extended upwardly from the edge of the bottom plate (371). A brush outlet (374a) and a socket mounting groove (374b) are formed in the front wall (373a). The brush outlet (374a) is formed in a groove shape at the upper end of the front wall (373a), and two end extensions (112) formed on the discharge brush (110) provided in the brush unit (105) are drawn out and protrude to the outside of the housing (370) through the brush outlet (374a). The socket mounting groove (374b) is formed on the inner wall surface of the front wall (373a). The end of the support (158) provided in the socket (150) of the brush unit (105) is mounted in the socket mounting groove (374b), thereby fixing the position of the brush unit (105).

[0114] The rear wall portion (373b) is formed by being in the form of a flat wall, facing the front wall portion (373a), and extending upward from the edge of the floor plate (371). The side grounding portion (364) of the grounding member (360) is in contact with and supported by the inner wall surface of the rear wall portion (373b).

[0115] Each of the two connecting wall portions (373c) is formed in a flat wall shape and faces each other, connecting the front wall portion (373a) and the rear wall portion (373b). Each of the two connecting wall portions (373c) is formed by protruding upward from the edge of the floor plate (371). Each of the two connecting wall portions (373c) is formed with a side opening (375a) that communicates with each of the two connecting wings (377). Each of the two grounding wings (366) provided on the grounding member (360) protrudes outward from the side wall (373) through the two side openings (375a) and is exposed, so that the grounding wing (366) is accommodated inside the corresponding connecting wing (377).

[0116] Each of the two coupling wings (377) is formed by protruding outward from each of the two coupling wall portions (373c) of the side wall (373). Each of the two coupling wings (377) communicates with the receiving space (379) of the housing (370) through a side opening (375a) formed in the coupling wall portion (373c). The grounding wing (366) of the grounding member (360) is mounted on the coupling wing (377). A through hole (378) is formed in the coupling wing (377). The through hole (378) is a hole through which a screw nail that couples the shaft grounding device (300) for the electric motor to the electric motor passes.

[0117] Referring to Fig. 27, the cover (380) covers the housing (370) and closes the receiving space (379). In this embodiment, the cover (380) is a resin injection molded product made of an electrically non-conductive material. Referring to Figs. 27, 28, and 30, the cover (380) has a cover plate portion (381) and two closing portions (385) formed by protruding from the edges of the cover plate portion (381).

[0118] The cover plate (381) is generally a flat, square plate shape and covers and closes the open top of the receiving space (379) formed in the housing (370). A closing portion (385) is positioned on each side of the cover plate (381).

[0119] Two closing portions (385) are formed by protruding from each side of the cover plate portion (381). Each of the two closing portions (385) blocks a side opening (375a) formed in the housing (370).

[0120] The ground wire (390) is electrically connected to the ground wing (366) provided on the ground member (360) by welding or the like.

[0121] Fig. 31 illustrates a state in which a shaft grounding device (300) for an electric motor is installed in an electric motor (M). Referring to Fig. 31, the shaft grounding device (300) for an electric motor is coupled to a housing of the electric motor (M) adjacent to a shaft (S) of the electric motor (M). The end of an end extension (112) provided to a discharge brush (110 in Fig. 4) provided to the shaft grounding device (300) for an electric motor is electrically connected by contacting the outer surface of the shaft (S) provided to the electric motor (M). The shaft grounding device (300) for an electric motor is fastened to the electric motor (M) by screw nails in two coupling wings (377) provided to the housing (370). The shaft grounding device (300) for an electric motor is grounded by an electrically conductive screw nail that contacts a grounding wing (366) provided on a grounding member (360 in FIG. 29) that contacts a discharge brush (110 in FIG. 4) and that fastens the shaft grounding device (300) for an electric motor to the electric motor (M). Additionally, the shaft grounding device (300) for an electric motor is grounded by connecting a grounding wire (390) to an external grounding terminal. The electric motor (M) is a rotary motor in which a shaft (S) rotates along an axis or a linear motor in which a shaft (S) reciprocates linearly along an axial direction.

[0122] Referring to FIG. 32, a shaft grounding device (400) for an electric motor according to a fourth embodiment of the present invention includes brush units (205), a unit mounting member (450) on which the brush units (205) are mounted, a grounding member (360) for grounding the brush units (205), a housing (370) that accommodates the brush units (205), the unit mounting member (450), and the grounding member (360) therein, and a cover (380) that covers the housing (370). Although not illustrated, the shaft grounding device (400) for an electric motor may further include a configuration of a grounding line (390) of the embodiment illustrated in FIG. 27.

[0123] The brush unit (205) is accommodated in the housing (370) while being seated on the unit mounting member (250). The brush unit (205) is the same as the brush unit (205) described above with reference to FIGS. 21 to 24. Each of the two end extensions (212) extends in the same direction from each of the two brush holders (220) and is arranged parallel. The belt surfaces of the two end extensions (212) are generally on the same plane. The two end extensions (212) are brought closer to each other as they go toward the ends. The ends of each of the two end extensions (212) protrude from the housing (370) and the cover (380) and are exposed to the outside. The outer extension section (216) is in surface contact with the grounding member (360). The lower extension section (217) is located below the unit mounting member (450). The lower extension section (217) is in surface contact with the grounding member (360).

[0124] Two brush holders (220) are arranged in parallel within the housing (370). The two brush holders (220) are coupled to one discharge brush (210). The brush holder (220) is mounted on the unit mounting member (450) to fix the position of the discharge brush (210). The brush holder (220) is mounted on the unit mounting member (450) so that the first holder member (230) is positioned lower than the second holder member (240).

[0125] The brush unit (205) may have only one brush holder (220) like the brush unit (205) described above with reference to FIGS. 21 to 24, and this also falls within the scope of the present invention.

[0126] Referring to Fig. 32, the unit mounting member (450) mounts the brush unit (205). The unit mounting member (450) is generally block-shaped. The unit mounting member (450) is accommodated inside the housing (370). In the present embodiment, the unit mounting member (450) is described as being a resin injection molded product of an electrically non-conductive material. The upper surface of the unit mounting member (450) faces the cover (380), and the lower surface of the unit mounting member (450) faces the bottom plate (371) of the housing (370). Two holder mounting grooves (452) are formed on the upper surface of the unit mounting member (450). One brush holder (220) is mounted in each of the two holder mounting grooves (452). Two outer extension sections (216) and a lower extension section (217) of the discharge brush (210) are located outside the unit mounting member (450).

[0127] The grounding member (360) has a configuration substantially identical to that of the grounding member (360) provided in the embodiments described in FIGS. 28, 29, and 30. The lower extension section (217) formed on the discharge brush (210) is in surface contact with the bottom grounding portion (361) of the grounding member (360), and the outer extension section (216) formed on the discharge brush (210) is in surface contact with the side grounding portion (364) of the grounding member (360). The lower extension section (217) of the discharge brush (210) is pressed between the bottom grounding portion (361) of the grounding member (360) and the unit mounting member (450), and the outer extension section (216) of the discharge brush (210) is pressed between the side grounding portion (364) and the unit mounting member (450).

[0128] The housing (370) has a configuration substantially identical to the housing (370) provided in the embodiments described in FIGS. 27 to 30.

[0129] The cover (380) has a configuration substantially identical to that of the cover (380) provided in the embodiments described in FIGS. 27 to 30.

[0130] While the present invention has been described through the above examples, the present invention is not limited thereto. The above examples may be modified or altered without departing from the spirit and scope of the present invention, and those skilled in the art will recognize that such modifications and variations also fall within the scope of the present invention.

Claims

1. A brush unit having a discharge brush made of a conductive material and a brush holder for fixing the discharge brush; and comprising a housing for accommodating the brush holder; The brush holder has a first holder member in which a brush catch groove is formed, and a second holder member in which a brush catch projection to be inserted into the brush catch groove is formed. The discharge brush has an end extension portion that extends so as to pass between the brush catch groove and the brush catch projection and extends from the brush holder so that the end is exposed to the outside of the housing. Shaft grounding device for electric motor.

2. In claim 1, Further comprising a grounding means of electrically conductive material that is in contact with and electrically connected to the discharge brush within the housing; Shaft grounding device for electric motor.

3. In claim 2, The above brush unit has two brush holders, The discharge brush further comprises an intermediate extension extending between the two brush holders and contacting the grounding means within the housing. Shaft grounding device for electric motor.

4. In claim 3, The above intermediate extension portion has two outer extension sections positioned outside the sides of each of the two brush holders, and a lower extension section positioned below the two brush holders, The above grounding means has a side grounding portion in contact with the two outer extension sections and a bottom grounding portion in contact with the lower extension section. Shaft grounding device for electric motor.

5. In claim 4, The above side grounding part and the above bottom grounding part are formed integrally, Shaft grounding device for electric motor.

6. In claim 4, The above side grounding part and the above floor grounding part are separate members, Shaft grounding device for electric motor.

7. In claim 1, The material of the above discharge brush includes carbon fiber. Shaft grounding device for electric motor.

8. In claim 1, The above housing is ring-shaped, The above brush holders are arranged in a plurality of rows in a circular direction. The above end extension extends radially inward, Shaft grounding device for electric motor.

9. In claim 1, The above housing has a box-shaped receiving portion that receives the brush holder. Shaft grounding device for electric motor.

10. In claim 9, The end of the above end extension is coupled to the housing of the motor so as to contact the outer surface of the shaft provided in the motor. Shaft grounding device for electric motor.

11. Discharge brush made of conductive material; and Includes a brush holder for fixing the above discharge brush, The brush holder has a first holder member in which a brush-catching groove is formed, and a second holder member in which a brush-catching protrusion to be inserted into the brush-catching groove is formed. The above discharge brush extends so as to pass between the brush engaging groove and the brush engaging projection, Brush unit for shaft grounding device for electric motor.

12. In claim 11, The above first holder member has coupling protrusions positioned on both sides with respect to the path through which the discharge brush passes, The second holder member is formed with coupling grooves into which each of the coupling protrusions is fitted. Brush unit for shaft grounding device for electric motor.

13. In claim 12, The second holder member has two wing parts in the form of walls positioned with the hook projection between them, The above joining grooves are formed in each of the two wing sections, Brush unit for shaft grounding device for electric motor.

14. In claim 11, The second holder member has coupling protrusions positioned on both sides of the path through which the discharge brush passes, The first holder member is formed with coupling grooves into which each of the coupling protrusions is fitted. Brush unit for shaft grounding device for electric motor.

15. In claim 14, The above first holder member has two wing parts in the form of walls positioned with the above-mentioned hook projection between them, The above joining grooves are formed in each of the two wing sections, Brush unit for shaft grounding device for electric motor.

Images