Gleichstrommotor

Abstract

DC motor with at least four poles, comprising: a commutator (9) having a cylindrical shape on an axis of an armature (8); a brush (10) arranged on an outer circumference of the commutator (9); a brush holding device (14) which holds the brush (10) and has insulating properties; a pressure component (15) arranged in the brush holder (14) for pressing the brush (10) towards the commutator (9); a first connecting plate (16) having conductive properties and arranged adjacent to the core (12) of the armature (8) in an axial direction, wherein all plus-side brushes (10a) or all minus-side brushes (10b) of the brush (10) are electrically connected to the first connecting plate via a respective connecting cable (21); and a second connection plate (17) having conductive properties and arranged opposite to the core (12) of the armature (8) via the first connection plate in the axial direction, wherein all the minus-side brushes (10b) or all the plus-side brushes (10a) are electrically connected to the second connection plate (17) via a respective connection cable (21), wherein the brush holder (14) has an inner peripheral opening facing the commutator (9) in a radial direction and an outer peripheral wall surface (14a) regulating an outer peripheral position of the pressure component (15) in the radial direction, the first connecting plate (16) and the second connecting plate (17) are arranged in parallel in the axial direction without electrical contact, wherein the brush holding device (14) is held between the first connecting plate (16) and the second connecting plate (17), the first connecting plate (16) has a slot (22) extending from the inner circumference or the outer circumference in the radial direction, the brush holding device (14) has a core side position regulating device (26, 27) which is engaged with the first connecting plate (16) to regulate a relative position, the core side position regulating device (26, 27) a projection part (26) projecting toward the core (12) of the armature (8) in the axial direction, and a fitting groove portion (27a) defined on both sides of the projection part (26) in a circumferential direction; the relative position in the circumferential direction is regulated by engagement between the projection part (26) and the slot (22), the relative position in the axial direction is regulated by engagement between at least a part of the slot (22) in the circumferential direction and the fitting groove portion (27a), and a width (A1) of the projection part (26) in the circumferential direction is greater than a width (B) of the brush (10) in the circumferential direction, wherein the first connecting plate (16) overlaps in the axial direction an end portion of the brush (10) which is adjacent in the axial direction to the core (12) of the armature (8) in a state in which the brush holding device (14) holding the brush (10) is attached to the first connecting plate (16).

Description

TECHNICAL FIELDThe present invention relates to a DC motor.BACKGROUNDThe document KR 2013 007 793 A describes a six-pole direct current motor of a magnet type. The DC motor has three plus-side brushes and three minus-side brushes disposed on an outer periphery of a cylindrical commutator. The brush is held by a brush holder having a box shape and pressed to the commutator by a spring disposed in the brush holder.The plus-side brush and the minus-side brush are electrically connected to a plus-side connection plate and a minus-side connection plate, respectively, by a respective lead wire. That is, the plus-side connecting plate electrically connects the three plus-side brushes, and the minus-side connecting plate electrically connects the three minus-side brushes.The brush holder is held between the plus-side connection plate and the minus-side connection plate which are arranged in parallel in the axial direction. The minus-side connection plate is fixed to an end frame of a motor that forms a part of a ground circuit. The plus-side connecting plate is disposed at one armature core side of the brush holder in the axial direction, and the minus-side connecting plate is disposed at the other side of the brush holder opposite to the armature core side in the axial direction.The document DE 10 2007 059 555 A1 describes a brush assembly for an electric machine, which consists of four annular plate elements stacked one on top of the other, namely two outer printed circuit boards, each of which is electrically conductively connected to one or more brushes, and two guide plates of electrically insulating material arranged therebetween, which have a shape with projections and depressions for forming radial guides for the brushes and receptacles for springs acting on the brushes. The springs are helical springs which are wound around a pin, the flat ends of which protruding beyond the spring are guided in a guide groove of the respective receptacle in a rotationally fixed manner and can latch behind a stop. For mounting the brush assembly, the conductor and guide plates are stacked and riveted in the axial direction and the brushes are then inserted into the guides in the radial direction and the springs are inserted into the receptacles.U.S. Pat. No. 7,256,527 B2 describes a brush holding device which comprises a brush holding device having a brush receiving chamber and a holding plate to which the brush holding device is fastened. The support plate is formed with a central hole in its central part, the central hole having a size that allows a commutator to move therethrough, and a pair of elongated holes opposing each other with respect to the opening portion, the elongated holes defining bridge portions with the opening hole. The brush holder has a thick-wall portion integral with a bottom wall of the brush housing chamber, the thick-wall portion being fitted with fitting grooves on its lateral sides. The bridge portions are inserted into the fitting grooves, so that the brush holder is fixed to the support plate such that the thick-wall portion is sandwiched between the bridge portions.US 4 668 874 A describes a method and apparatus for shutting down a starter that interrupts the ground line within the starter housing and interrupts the electrical passage between the commutator and the ground by physically displacing a portion of the ground line. A cable attached to a switch within the starter housing extends out of the starter and into the cab of the vehicle.US 7 592 731 B2 describes a rotating electric machine having a field winding wound on field magnetic iron cores and an armature having an armature winding connected in series with the field winding via a pair of brushes and a corresponding pair of connecting lines electrically connected to the brushes. A balance winding for balancing the magnetic field strengths of the field poles is wound around and supported by successive field magnetic iron cores, one end of which is fixedly connected to one of the connection lines and electrically connected thereto, and the other end of which is electrically connected to and fixedly connected to the other connection line.SUMMARYThe magnet type six-pole DC motor needs the plus-side connecting plate electrically connecting the three plus-side brushes. The plus-side connecting plate is disposed adjacent to the armature core with respect to the brush holder. However, a terminal portion (a tab) connecting each commutator segment to an armature coil is disposed adjacent to the armature core with respect to the brush holder. That is, the terminal portion (the end) of a segment is positioned on the armature core side in the axial direction, and a wire of the armature coil is connected to the terminal portion. For this reason, when the plus-side connection plate is disposed adjacent to the core side, it is necessary to provide a space for securing electrical insulation between the terminal portion of a segment and the plus-side connection plate, so that the overall length of a motor becomes large.It is an object of the present invention to provide a DC motor in which a connection plate is disposed on the core side to electrically connect all plus-side brushes or all minus-side brushes so that the total length of the DC motor in an axial direction is made smaller while an insulation space is secured between the terminal portion of a commutator segment and the connection plate.This object is achieved by a direct current motor according to claim 1 or a direct current motor according to claim 2.Advantageous further developments are specified in the dependent claims.According to one aspect, a direct current motor having at least four poles includes: a commutator having a cylindrical shape on an axis of an armature; a brush disposed on an outer periphery of the commutator; a brush holder holding the brush and having insulating properties; a pressing component disposed in the brush holder to press the brush toward the commutator; a first connection plate having conductive properties and disposed adjacent to a core of the armature in an axial direction, wherein all of the plus-side brushes or all of the minus-side brushes of the brush are electrically connected to the first connection plate through a respective lead wire; and a second connecting plate having conductive properties and being disposed on the other side of the first connecting plate via the brush holding means, i.e., opposite to the core of the armature in the axial direction, wherein all of the minus-side brushes or all of the plus-side brushes are electrically connected to the second connecting plate via a respective lead wire.The brush holder has an inner circumferential opening facing the commutator in a radial direction and an outer circumferential wall surface that adjusts an outer circumferential position of the pressing component in the radial direction. The first connection plate and the second connection plate are arranged in parallel in the axial direction without electrical contact, and the brush holding device is held between the first connection plate and the second connection plate.The first connection plate has a slit extending from the inner periphery or the outer periphery in the radial direction. The brush holder has a core side position regulating means engaged with the first link plate to regulate a relative position. The core side position regulating means includes a protrusion part protruding toward the core in the axial direction and a fitting groove portion defined on both sides of the protrusion part in a circumferential direction. The relative position in the circumferential direction is regulated by the protrusion part engaged with the slit, and the relative position in the axial direction is regulated by an engagement between at least a part of sides of the slit in the circumferential direction and the fitting groove. A width of the protrusion part in the circumferential direction is larger than a width of the brush in the circumferential direction.The circumferential width of the protrusion part inserted into the slit of the first connection plate is larger than the circumferential width of the brush. Consequently, the height of the brush holder having the protrusion part in the axial direction on the core side can be short. Accordingly, the position of the fitting groove portion of the brush holder can be displaced away from the core in the axial direction, and the position of the first connection plate fitted into the fitting groove portion can be brought close to the other side opposite to the core side. As a result, a distance between the first connection plate and the second connection plate in the axial direction can be made small. Thus, the overall length of the motor can be made short while securing the insulation space between a tab (a terminal portion connected to the armature coil) of a commutator segment and the first connection plate.BRIEF DESCRIPTION OF THE DRAWINGThe above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The following are shown: FIG. 1A is a sectional view illustrating a brush holder according to a first embodiment, and FIG. 1B is a sectional view of a brush holder of a comparative example; FIG. 2 is a perspective view illustrating a brush assembly according to the first embodiment; FIG. 3 is an enlarged sectional view illustrating a rear side of a motor according to the first embodiment; FIG. 4A is a diagram illustrating the rear side of the motor according to the first embodiment, and FIG. 4B is a diagram illustrating a rear side of a motor according to the comparative example; FIG. 5 is a sectional view of a starter according to the first embodiment; FIG. 6 is a perspective view illustrating a brush assembly according to a second embodiment; FIG. 7 is a perspective view illustrating a brush assembly according to a third embodiment; FIG. 8 is a sectional view illustrating a brush holder according to a fourth embodiment; FIG. 9 is a line connection diagram between a magnetic field coil of a motor and an armature according to a fifth embodiment; FIG. 10 is a line connection diagram between a magnetic field coil of a motor and an armature according to a fifth embodiment; FIG. 11 is a line connection diagram between a magnetic field coil of a motor and an armature according to a sixth embodiment; FIG. 12 is a line connection diagram between a magnetic field coil of a motor and an armature according to a sixth embodiment; and FIG. 13 is a line connection diagram of a general DC motor.DETAILED DESCRIPTIONEmbodiments of the present disclosure will be described below with reference to the drawings. In the embodiments, a part corresponding to a matter described in a preceding embodiment may be assigned the same reference numeral, and redundant description for the part may be omitted. When only a part of a configuration is described in one embodiment, another foregoing embodiment may be applied to the other parts of the configuration. The parts may be combined, although it is not explicitly described that the parts may be combined. The embodiments may be partially combined, although it is not explicitly described that the embodiments may be combined, provided that no damage is caused by the combination.(First Embodiment)In a first embodiment, a DC motor is applied to a starter 1 for starting an internal combustion engine. As shown in FIG. 5, the starter 1 has a pinion 4 on an axis of an output shaft 3 rotated by a motor 2. The gear 4 is pushed away from the motor 2 (leftward in FIG. 5 ) by the output shaft 3 using the attractive force of an electromagnetic switch 5 including a solenoid to engage with a ring gear 6 of the engine. This system is generally referred to as a pinion drive system. The engine 2 will be explained in detail below, while the basic structure and operation of the starter 1 are generally known.The motor 2 is a direct current motor having four or more poles in which a permanent magnet 7 is used to form a magnetic field pole. For example, the number of poles may be six. The motor 2 includes an armature 8, a commutator 9, and a brush 10. The armature 8 is arranged on an inner periphery of the magnetic field pole via an air gap. The commutator 9 has a cylindrical shape on the axis of the armature 8. The brush 10 is disposed on the outer periphery of the commutator 9.The commutator 9 includes an insulator base 9 aand a plurality of commutator segments 9 b. The insulator base 9 ais in the form of a cylinder and is made of, for example, a resin material. The commutator segments 9 bare held by the insulator base 9 aand are arranged in a cylindrical shape. The insulator base 9 ais fixed to the outer periphery of a shaft 11 of the armature 8 at the end portion by press fitting. The commutator segments 9b are mutually insulated from each other by the insulator base 9a. A coil 13 of the armature 8 is connected to a tab 9 c(a connection portion) of the commutator 9 at the end (left end of the commutator segments 9 bin FIG. 5 ) adjacent to a core 12 of the armature 8 in the axial direction.The brush 10 includes three plus-side brushes 10 aand three minus-side brushes 10 bdisposed at equal intervals in the circumferential direction of the commutator 9. A brush assembly shown in FIG. 2 includes, in addition to the brush 10, a brush holder 14, a pressing component 15, a first connecting plate 16, and a second connecting plate 17.The brush holder 14 is made of an insulating component such as resin and has a box shape. The brush holder 14 has an inner circumferential opening facing the commutator 9 in the radial direction and a wall surface 14 a(see FIG. 2 ) on the outer circumferential radial surface.As shown in FIG. 3, the brush holder 14 includes a brush storage chamber 14 bthat stores the brush inside and a printing component storage chamber 14 cthat stores the printing component 15 (on the outer circumferential side in the radial direction). The brush storage chamber 14 bis disposed between the commutator 9 and the pressure component storage chamber 14 c.The pressing component 15 may be, for example, a coil spring stored in the pressing component storage chamber 14 cof the brush holder. The wall surface 14 aof the brush holder 14 adjusts the outer circumferential position of the pressing component 15 in the radial direction, and the pressing component 15 presses the brush 10 toward the commutator 9.As shown in FIG. 3, the axial dimension X of the pressing component 15 (an outer diameter of the coil spring) is smaller than the axial length Y of the brush 10 in the axial direction. Further, the center of the pressing component 15 in the axial direction is located at approximately the same position as the center of the brush 10 in the axial direction.Each of the first connection plate 16 and the second connection plate 17 is made of metal and has a ring shape with a central circular hole (an opening) larger than the outer diameter of the commutator 9 at the central part in the radial direction. The first connection plate 16 and the second connection plate 17 are arranged parallel to each other and without electrical contact in the axial direction. The brush holder 14 is held between the first connecting plate 16 and the second connecting plate 17.The first connecting plate 16 is disposed adjacent to the armature core, and the second connecting plate 17 is disposed on the other side opposite to the armature core via the first connecting plate 16. In other words, the first connection plate 16 is disposed on the core side and the second connection plate 17 is disposed on the other side. Hereinafter, the core side in the axial direction is a left side in FIG. 3 and close to the armature core 12 with respect to the brush holder 14.The first connection plate 16 is electrically connected to an M terminal bolt 18 (see FIG. 5 ) of the electromagnetic switch 5 via a lead wire (not shown). The second connection plate 17 is fixed to the end frame 19 of the motor 2 with the bolt 20 and is electrically connected to the end frame 19. The end frame 19 may correspond to a motor housing forming part of a ground circuit.As shown in FIG. 2, each of the three plus-side brushes 10 ais electrically connected to a surface of the first connection plate 16 opposite to the armature core via a lead wire. Each of the three minus-side brushes 10 bis connected to a core side surface of the second connection plate 17 via a lead cable 21.Each of the first connection plate 16 and the second connection plate 17 has a plurality of slits 22 at positions where the brush holder 14 is disposed. The slit 22 is opened at the inner periphery of the first connecting plate 16 and extends outward from the inner periphery in the radial direction of the first connecting plate 16 and the second connecting plate 17. a flat part 23 is defined between the adjacent slits 22 in the circumferential direction, having a width in the radial direction approximately equal to the length of the slit 22 in the radial direction.As shown in FIG. 2, the first connection plate 16 has a spreading part 24 that electrically connects the adjacent flat parts 23 at the both sides of the slot 22 in the circumferential direction. The spreading part 24 is defined on the same plane as the flat part 23 and extends around the radial outside of the slot 22. The both sides of the spreading part 24 in the circumferential direction are connected to the respective flat parts 23.That is, the radial outer periphery of the slit 22 is not opened from the outer periphery of the first connection plate 16 and is closed by the spreading part 24. Since the first connecting plate 16 has the spreading part 24 on the radially outer side of the outer periphery of the flat part 23 in the radial direction, an interval space between the outer periphery of the spreading part 24 and the inner periphery of the end frame 19 in the radial direction becomes small. As shown in FIG. 3, an insulation component 25 having a ring shape is disposed between the outer periphery of the spreading part 24 and the end frame 19 to ensure insulation.Next, the core side shape of the brush holder 14 attached to the first connecting plate 16 will be explained in detail. The brush holder 14 includes a core-side position regulating means attached to the first connecting plate 16 for regulating a relative position of the brush holder 14 with respect to the first connecting plate 16. As shown in FIG. 2, the core side position regulating means includes a protrusion part 26 that regulates the relative position with respect to the first connection plate 16 in the circumferential direction, and a plate fitting part 27 that regulates the relative position with respect to the first connection plate 16 in the axial direction and the radial direction (outward in the radial direction).The protrusion part 26 protrudes toward the armature core 12 in the axial direction and corresponds to the brush storage chamber 14 b. When the brush holder 14 is attached to the first connecting plate 16, the protrusion part 26 is inserted into the slot 22 of the first connecting plate 16.As shown in FIG. 1A, the width A 1 of the protrusion part 26 in the circumferential direction is larger than the width B of the brush 10 in the circumferential direction. In contrast, in a brush holder 14 of a comparative example illustrated in FIG. 1B, the width A 2 of the protrusion part 26 in the circumferential direction is smaller than the width B of the brush 10 in the circumferential direction. FIG. 1A is a sectional view taken along a line Ia-Ia in FIG. 4A according to the first embodiment, and FIG. 1B is a sectional view taken along a line Ib-Ib in FIG. 4B according to the comparative example.As shown in FIG. 2, the plate fitting part 27 has a fitting groove portion 27a on both sides of the brush storage chamber 14b in the circumferential direction, while the brush storage chamber 14b is opened at the inner periphery of the brush holder 14. As shown in FIGS. 1A and 2, the fitting groove portion 27 ahas a U-shape in cross section. In other words, the groove is opened to the outer circumferential side in the radial direction and recessed inward in the radial direction. Further, the groove is opened to the outside (opposite to the protrusion part) in the circumferential direction. When the protrusion part 26 is inserted into the slot 22 of the first connection plate 16, both sides of the slot 22 in the circumferential direction are fitted at the fitting groove portion 27 aat the inner circumferential side.As shown in FIG. 1A, the fitting groove portion 27 ais formed at the position overlapping with the core side end portion (upper end portion) of the brush 10 stored in the brush storage chamber 14 bin the axial direction. That is, in the state where the brush holder 14 is attached to the first connection plate 16, the first connection plate 16 faces the core side end portion of the brush 10 in the circumferential direction.The protrusion part 26 has a step part 28 (see FIG. 3 ) at both sides of the protrusion part 26 in the circumferential direction and the radially outer side of the protrusion part 26 except for the plate fitting part 27. A height difference is defined between the protrusion part 26 and the step part 28. The height of the step part 28 is lower than that of the protrusion part 26 on the core side in the axial direction. On the other side opposite to the core side, however, the surface of the fitting groove portion 27 ais formed to have the same height as the step part 28. The height on the core side in the axial direction means an axial distance from the same position in the axial direction (for example, the axial center of the brush holder 14) to the core side in the axial direction.The step part 28 is formed because the dimension X of the pressing component 15 in the axial direction is smaller than the length Y of the brush 10 in the axial direction. That is, the height difference is formed between the protrusion part 26 and the step part 28 corresponding to the vertical interval between the core side end surface of the brush storage chamber 14 band the core side end surface of the spring storage chamber 14 cin the axial direction. The dimension of the height difference in the axial direction (height difference between the step part 28 and the protrusion part 26 in the axial direction) is larger than the thickness of the first connection plate 16.The relative position of the brush holder 14 with respect to the first connecting plate 16 in the circumferential direction is regulated by inserting the protrusion part 26 into the slot 22. The relative position of the brush holder 14 with respect to the first connecting plate 16 in the axial direction and the radial direction is regulated by the engagement between the inner circumferential side (inner circumference of both sides of the slit 22 in the circumferential direction) of the first connecting plate 16 and the fitting groove portion 27 a.As shown in FIG. 1A, the brush holder 14 has the other-side position regulating means having the protrusion part 26 and the plate fitting part 27 on the other side in the axial direction similar to the core side in the axial direction. The relative position with respect to the second link plate 17 is regulated by the other-side position regulating means. However, the relationship between the width A 1 of the protrusion part 26 in the circumferential direction and the width B of the brush 10 in the circumferential direction need not be the same as that of the core side. That is, A 1<B may be possible on the other hand.According to the first embodiment, as shown in FIG. 1A, in the brush holder 14 formed on the core side in the axial direction, the width A 1 of the protrusion part 26 in the circumferential direction is larger than the width B of the brush 10 in the circumferential direction. Consequently, as compared with the height C 2 in the comparative example shown in FIG. 1B, the height C 1 of the brush holder 14 according to the first embodiment in the axial direction may be short. Specifically, the height of the protrusion part 26 and the disk fitting part 27 on the core side in the axial direction in FIG. 1A is made short as compared with FIG. 1B, so that the fitting groove portion 27 aof the disk fitting part 27 can be made to overlap with the core side end portion of the brush 10 stored in the brush storage chamber 14 in the axial direction. Thus, the distance between the first connection plate 16 and the second connection plate 17 in the axial direction can be made small. Accordingly, the total length D 1 of the motor according to the first embodiment in FIG. 4A may be shorter than the total length D 2 of the motor according to the comparative example in FIG. 4B. Here, FIG. 4A is a diagram showing a rear side of the motor 2 including the brush assembly according to the first embodiment, and FIG. 4B is a diagram showing a rear side of a motor 2 including a brush assembly according to the comparative example.According to the first embodiment, the spreading part 24 of the first connection plate 16 is formed on the same plane as the flat part 23. Further, the spreading part 24 of the first connecting plate 16 is disposed on the core side surface of the step part 28 of the brush holder 14 formed on the core side. That is, the spreading part 24 is formed to overlap with the protrusion part 26 of the brush holder 14 in the axial direction. In other words, the spreading part 24 is not disposed on the core side of the protrusion part 26 in the axial direction. Consequently, the full length of the motor 2 is not affected because it is not necessary to prepare a space for arranging the spreading part 24 in the axial direction.(Second Embodiment)The spreading part 24 of the first connecting plate 16 is modified in a second exemplary embodiment. As shown in FIG. 6, the spreading part 24 is formed to protrude toward the core side in the axial direction with respect to the first connection plate 16 when extending over the slit 22 in the circumferential direction. Specifically, when the protrusion part 26 of the brush holder 14 is inserted into the slot 22, the spreading part 24 may not interfere with the protrusion part 26 due to a shape of a tunnel over the slot 22.The spreading part 24 does not protrude outward in the radial direction from the outer periphery of the flat part 23 and is positioned inside the outer diameter of the flat part 23, so that an insulation component 25 of the first embodiment is unnecessary. In addition, the spreading part 24 is formed on the outer circumferential side of the tab 9 cof the commutator segment 9 bin the radial direction. Consequently, a sufficient insulation distance with respect to the armature coil 13 or the tab 9 cis secured while the spreading part 24 is in the form of a tunnel protruding toward the core side in the axial direction. The other structure according to the second embodiment is the same as that in the first embodiment, so that the overall length of the motor 2 can be shortened similarly to the first embodiment.(Third Embodiment)The spreading part 24 of the first connecting plate 16 is modified in a third exemplary embodiment. As shown in FIG. 7, the spreading part 24 is bent toward the core side in the axial direction with respect to the flat part 23 of the first connection plate 16 at approximately 90 degrees. In this case, as in the second embodiment, the spreading part 24 does not protrude outward from the outer diameter of the flat part 23, so that the insulation component 25 is unnecessary. In addition, the spreading part 24 is disposed on the outer circumferential side of the tab 9 cof the commutator segment 9 bin the radial direction. Consequently, a sufficient insulation distance with respect to the armature coil 13 or the tab 9 cis secured while the spreading part 24 is bent by about 90 degrees toward the core side in the axial direction.According to the third embodiment, the overall length of the motor 2 can be shortened similarly to the first embodiment because the other configuration in the third embodiment is the same as that in the first embodiment.(Fourth Embodiment)In a fourth embodiment, unlike the first embodiment, the fitting groove portion 27 aof the plate fitting part 27 of the brush holder 14 does not overlap with the core side end portion of the brush 10 in the axial direction. As shown in FIG. 8, the fitting groove portion 27 aand the core side end portion of the brush 10 do not overlap each other in the circumferential direction.As in the first embodiment, the width A 1 of the protrusion part 26 in the circumferential direction is larger than the width B of the brush 10 in the circumferential direction, while the protrusion part 26 is formed on the core side of the brush holder 14 in the axial direction. For this reason, the height of the protrusion part 26 and the plate fitting part 27 on the core side in the axial direction can be made small while the fitting groove portion 27 aand the core side end portion of the brush 10 do not overlap in the axial direction. Consequently, the axial length of the brush holder 14 can be made small. As a result, the distance between the first connection plate 16 and the second connection plate 17 in the axial direction can be made small as compared with the comparative example shown in FIG. 1B, so that the overall length of the motor 2 can be shortened.(Fifth Embodiment)In a fifth embodiment, the motor 2 has an electromagnetic magnetic field 40. As shown in FIG. 9, the motor 2 includes magnetic field coils 29 that are energized to form magnetic field poles as an electromagnetic magnetic field 40, and the armature 8 in which the coil 13 is wound in a wave winding. The magnetic field coil 29 is connected in series with the armature coil 13. In addition, the number of brushes (the core side brushes 10) connected to the first connection plate 16 via the lead wire 21 is less than half the number of magnetic field poles. In FIG. 9, the number of the brushes 10 aconnected to the first connection plate 16 by the lead wire 21 is two. Further, the magnetic field coil 29 and the first connection plate 16 are electrically connected to each other via a lead 30.The wire connection can be easily made even while the number of terminals of the magnetic field coils 29 connected to the first connection plate 16 is different from the number of the core side brushes 10. For example, the number of the core side brushes 10 can be reduced to two (or one) with respect to a system having six magnetic field poles in which the magnetic field coils 29 are connected in two-series and three-parallel in FIG. 9.FIG. 9 shows an example of a series-winding type motor 2. alternatively, the present disclosure may be applied to a mixed-winding type motor in which the magnetic field coil 29 and the armature coil 13 are connected in series-parallel. The core side brush 10 is not limited to the plus side brush 10 aand may be the minus side brush 10 b. For example, as shown in FIG. 10, when the magnetic field coil 29 is connected to the ground side with respect to the armature 8, the minus side brush 10 bis connected to the first connection plate 16, and the plus side brush 10 ais connected to the second connection plate 17.(Sixth Embodiment)In a sixth embodiment, the motor 2 has an electromagnetic magnetic field 40 in which all the magnetic field coils 29 are connected in series or two-parallel. FIG. 11 illustrates an example of the magnetic field 40 having six poles, three-series and two-parallel.Fig. 13 illustrates a conventional well-known DC motor having an electromagnetic magnetic field 40, each plus-side brush 10a being connected to the magnetic field coil 29 via a respective line 30. For this reason, the number of the wires 30 needs to be the same as that of the plus-side brushes 10 a. In FIG. 13, the number of the wires 30 is two.In contrast, as shown in FIG. 11, according to the motor 2 according to the sixth embodiment, the magnetic field coil 29 and the first connection plate 16 can be connected to a line 30 regardless of the number of the core side brushes 10. The engine 2 can be manufactured at a low cost with the minimum number of components.As shown in FIG. 12, the magnetic field coil 29 may be connected to the ground side with respect to the armature 8 according to the sixth embodiment. In this case, the minus side brush 10 bis connected to the first connecting plate 16, and the plus side brush 10 ais connected to the second connecting plate 17.(Modification)In the first embodiment, the plus side brushes 10 aare connected to the first connection plate 16, and the minus side brushes 10 bare connected to the second connection plate 17. Alternatively, the plus side brushes 10 amay be connected to the second connection plate 17, and the minus side brushes 10 bmay be connected to the first connection plate 16. However, it is necessary to establish electrical insulation between the second connection plate 17 and the end frame 19 when the second connection plate 17 is fixed to the end frame 19 of the motor 2.Similarly to the core side, the protrusion part 26 of the brush holder 14 can be inserted into the slit 22 of the second connection plate 17 on the other side of the brush holder 14 in the axial direction. Alternatively, the protrusion part 26 may be press-fitted into the slit 22 in the axial direction.It will be understood that such changes and modifications are within the scope of the present disclosure as defined by the appended claims.A brush holder (14) has a core side position regulating means (26, 27) which engages with a first link plate (16) to regulate a relative position. The core side position regulating means includes a protrusion part (26) protruding toward an armature core (12) in the axial direction, and a fitting groove portion (27a) defined on both sides of the protrusion part (26) in a circumferential direction. The relative position in the circumferential direction is regulated by an engagement between the protrusion part (26) and a slit (22) of the first connection plate (16). The relative position in the axial direction is regulated by engagement between sides of the slit ( 22) and the fitting groove portion ( 27 a). A width (A1) of the protrusion part (26) in the circumferential direction is larger than a width (B) of a brush (10) in the circumferential direction.

Claims

A direct current motor having at least four poles, comprising: a commutator (9) having a cylindrical shape on an axis of an armature (8); a brush (10) disposed on an outer periphery of the commutator (9); a brush holder (14) that holds the brush (10) and has insulating properties; a pressing component (15) disposed in the brush holder (14) to press the brush (10) toward the commutator (9); a first connection plate (16) having conductive properties and disposed adjacent to the core (12) of the armature (8) in an axial direction, wherein all of the plus-side brushes (10a) or all of the minus-side brushes (10b) of the brush (10) are electrically connected to the first connection plate via a respective connection cable (21); and a second connection plate (17), the conductive properties and being arranged opposite to the core (12) of the armature (8) via the first connection plate in the axial direction, wherein all of the minus-side brushes (10b) or all of the plus-side brushes (10a) are electrically connected to the second connection plate (17) via a respective lead wire (21), wherein the brush holder (14) has an inner circumferential opening facing the commutator (9) in a radial direction and an outer circumferential wall surface (14a) regulating an outer circumferential position of the pressing component (15) in the radial direction, the first connection plate (16) and the second connection plate (17) are arranged in the axial direction in parallel without electrical contact, wherein the brush holder (14) is held between the first connection plate (16) and the second connection plate (17), the first connecting plate (16) has a slit (22) extending from the inner periphery or the outer periphery in the radial direction, the brush holder (14) has a core side position regulating means (26, 27) engaged with the first connecting plate (16) to regulate a relative position, the core side position regulating means (26, 27) has a protrusion part (26) protruding toward the core (12) of the armature (8) in the axial direction, and a fitting groove portion (27a) defined on both sides of the protrusion part (26) in a circumferential direction; the relative position in the circumferential direction is regulated by an engagement between the protrusion part (26) and the slit (22), the relative position in the axial direction is regulated by an engagement between at least a part of sides of the slit (22) in the circumferential direction and the fitting groove portion (27a), and a width (A1) of the protrusion part (26) in the circumferential direction is larger than a width (B) of the brush (10) in the circumferential direction, wherein the first connection plate (16) in the axial direction overlaps an end portion of the brush (10) adjacent to the core (12) of the armature (8) in the axial direction in a state where the brush holder (14) holding the brush (10) is attached to the first connection plate (16).A DC motor having at least four poles, comprising: a commutator (9) having a cylindrical shape on an axis of an armature (8); a brush (10) disposed on an outer periphery of the commutator (9); a brush holder (14) that holds the brush (10) and has insulating properties; a pressing component (15) disposed in the brush holder (14) to press the brush (10) toward the commutator (9); a first connection plate (16) having conductive properties and disposed adjacent to the core (12) of the armature (8) in an axial direction, wherein all of the plus-side brushes (10a) or all of the minus-side brushes (10b) of the brush (10) are electrically connected to the first connection plate (16) via a respective lead wire (21); a second connection plate (17) having conductive properties and arranged opposite to the core (12) of the armature (8) via the first connection plate (16) in the axial direction, wherein all of the minus-side brushes (10b) or all of the plus-side brushes (10a) are electrically connected to the second connection plate (17) via a respective lead wire (21), wherein the brush holder (14) has an inner circumferential opening opposing the commutator (9) in a radial direction and an outer circumferential wall surface (14a) regulating an outer circumferential position of the pressing component (15) in the radial direction, the first connection plate (16) and the second connection plate (17) are arranged in the axial direction in parallel without electrical contact, wherein the brush holder (14) is held between the first connecting plate (16) and the second connecting plate (17), the first connecting plate (16) has a slit (22) extending from the inner periphery or the outer periphery in the radial direction, the brush holder (14) has a core side position regulating means (26, 27) engaged with the first connecting plate (16) to regulate a relative position, the core side position regulating means (26, 27) has a protrusion part (26) protruding toward the core (12) of the armature (8) in the axial direction, and a fitting groove portion (27a) defined on both sides of the protrusion part (26) in a circumferential direction; the relative position in the circumferential direction is regulated by an engagement between the protrusion part (26) and the slit (22), the relative position in the axial direction is regulated by an engagement between at least a part of sides of the slit (22) in the circumferential direction and the fitting groove portion (27a), and a width (A1) of the protrusion part (26) in the circumferential direction is larger than a width (B) of the brush (10) in the circumferential direction, wherein the commutator (9) includes a plurality of commutator segments (9b) insulated from each other and arranged in a cylindrical state and a connection portion (9c) that is an end of the respective commutator segments (9b), the connection portion being arranged adjacent to the core (12) of the armature (8) in the axial direction, wherein an armature coil (13) of the armature (8) is electrically connected to the connection portion, and the first connection plate (16) has a spreading part (24), connecting the sides of the slit ( 22) to each other in the circumferential direction at a position on an outer side of an outer periphery of the connecting portion ( 9 c) in the radial direction.The DC motor according to claim 1, wherein the commutator (9) comprises a plurality of commutator segments (9b) insulated from each other and arranged in a cylindrical state, and a connecting portion (9c) that is one end of the respective commutator segments (9b), the connecting portion (9c) is arranged adjacent to the core (12) of the armature (8) in the axial direction, an armature coil (13) of the armature (8) is electrically connected to the connecting portion (9c), and the first connecting plate (16) has a spreading part (24) that connects the sides of the slot (22) to each other in the circumferential direction at a position on an outer side of an outer periphery of the connecting portion (9c) in the radial direction.The DC motor according to claim 2 or 3, wherein the brush holder (14) has a step part (28) disposed on an outer side of the protrusion part (26) in the radial direction and disposed adjacent to the core (12) of the armature (8) in the axial direction, a height difference is defined between the step part (28) and the protrusion part (26), a height of the step part (28) is lower than that of the protrusion part (26) in the axial direction, and the spreading part (24) is disposed at a surface of the step part (28) adjacent to the core (12) of the armature (8) in a state where the brush holder (14) is attached to the first connection plate (16).The DC motor according to claim 4, wherein the pressing component (15) has a dimension (X) in the axial direction and the dimension of the pressing component (15) is smaller than a length (Y) of the brush (10) in the axial direction, the brush holder (14) has a brush storage chamber (14b) storing the brush (10), the brush storage chamber (14b) being opened to the inner circumference in the radial direction, and a pressing component storage chamber (14c) storing the pressing component (15), the brush (10) being disposed between the commutator (9) and the pressing component storage chamber (14c), the protrusion part (26) being formed to correspond to the brush storage chamber (14b) on a side adjacent to the core (12) of the armature (8) in the axial direction, and the step part (28) is formed to correspond to the pressure component storage chamber (14c) on a side adjacent to the core (12) of the armature (8) in the axial direction.The DC motor according to claim 2 or 3, wherein the spreading part (24) extends across the slit (22) in the circumferential direction and protrudes toward the core (12) of the armature (8) in the axial direction with respect to a surface of the first connection plate (16) that is opposed to the core (12) of the armature (8).The DC motor according to claim 2 or 3, wherein the spreading part (24) is bent to extend toward the core (12) of the armature (8) in the axial direction with respect to a surface of the first connection plate (16) opposing the core (12) of the armature (8).The DC motor according to any one of claims 2 to 7, wherein all the plus-side brushes (10a) are electrically connected to the first connection plate (16) having the spreading part (24), and all the minus-side brushes (10b) are electrically connected to the second connection plate (17).The DC motor according to claim 8, wherein the second connection plate (17) is directly fixed to a motor housing (19) forming a part of a ground circuit, and is electrically connected to the motor housing (19).The DC motor according to any one of claims 1 to 9, further comprising: an armature (8) in which a coil (13) is wound around a core (12) in a wave winding; and a magnetic field coil (29) connected in series or in series-parallel to the coil (13) of the armature (8), wherein the magnetic field coil (29) is energized to form magnetic field poles, wherein the number of the brushes (10) connected to the first connection plate (16) through the connection cable (21) is less than half the number of the magnetic field poles, and the magnetic field coil (29) and the first connection plate (16) are electrically connected.The DC motor according to any one of claims 1 to 9, further comprising: a plurality of magnetic field coils (29) that are energized to form magnetic field poles, wherein the magnetic field coils (29) are connected in series or two-parallel, and the magnetic field coils (29) and the first connection plate (16) are electrically connected to each other.

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