Bus bar holder

Abstract

To improve the possibility of ensuring insulation between bus bars.SOLUTION: A bus bar holder holds a plurality of bus bars electrically connected to a coil included in a motor and to a control circuit that controls the motor. The bus bar holder comprises an annular holder body that accommodates the plurality of bus bars. Each bus bar has an exposed part on an inner peripheral surface, which is a radially inner face of the holder body, the exposed part being exposed toward the radial inside of the holder body. On the inner peripheral surface, a processing part that makes a creepage distance longer than in a case where processing is not performed is formed between the exposed parts.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a bus bar holder. [Background technology]

[0002] Conventionally, bus bars have been used to electrically connect a control circuit formed on a substrate to a coil provided in a motor. The bus bars are often held in a bus bar holder to establish a predetermined positional relationship with the motor and the control circuit. For example, Patent Document 1 discloses a configuration in which a bus bar electrically connected to the coil of a motor is held in a bus bar holder and disposed at the axial end of the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-158797 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional bus bar holders are made of resin to insulate the bus bars from each other, but this does not take into consideration the possibility of poor insulation when a high voltage is applied to the motor.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to increase the possibility of ensuring insulation between bus bars. [Means for solving the problem]

[0006] In one embodiment, a busbar holder is provided that holds a plurality of busbars that are electrically connected to a coil provided in a motor and to a control circuit that controls the motor, and the busbar holder includes an annular holder body that accommodates the plurality of busbars, and the busbars have exposed portions that are exposed toward the radially inner side of the holder body on the inner surface, which is the radially inner surface of the holder body, and the inner surface has processed portions formed between the exposed portions that make the creepage distance longer than if the processed portions were not processed.

[0007] In the above configuration, processed portions are formed between the bus bars exposed radially inward of the holder body. The processed portions are structured to increase the creepage distance along the inner circumferential surface of the holder body compared to when the processed portions are not formed. Therefore, when the processed portions are present, it is more likely that insulation between the bus bars can be ensured than when the processed portions are not present. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of an electric water pump including a bus bar holder. [Figure 2] FIG. 2 is a perspective view of a cross section of an electric water pump including a bus bar holder. [Figure 3] FIG. [Figure 4] 1 is a view of the busbar and the busbar holder as viewed along the axial direction. [Figure 5] FIG. 2 is a perspective view showing a bus bar and a bus bar holder together with a stator. [Figure 6] 6A to 6C are perspective views of the bus bar. DETAILED DESCRIPTION OF THE INVENTION

[0009] Here, the embodiment will be described in the following order. (1) Electric water pump configuration (2) Busbar holder configuration (3) Other embodiments

[0010] (1) Electric water pump configuration Fig. 1 is a schematic cross-sectional view of an electric water pump 1 including a bus bar holder according to this embodiment. Fig. 2 is a perspective view of a schematic cross-section of the electric water pump 1. The electric water pump 1 includes a pump 11, a motor 12 that drives the pump 11, and a control circuit 13 that controls the motor 12.

[0011] Control circuit 13 is housed in driver housing 22 and mounted on control board 131. Control circuit 13 is a circuit for driving motor 12. Bus bar 110 is electrically connected to control circuit 13 mounted on control board 131. Bus bar 110 is positioned by terminal guides 210 provided on holder 200 attached to the end of the rotating shaft of motor 12, and is inserted into through holes formed in control board 131. Bus bar 110 is electrically connected to wiring provided in the through holes, and is thereby electrically connected to control circuit 13.

[0012] The motor 12 is housed in a body housing 21 and includes a stator 121 and a rotor 122. An insulator 123 is provided between the stator 121 and the rotor 122. The insulator 123 is a member that ensures insulation between the stator 121 and the rotor 122.

[0013] The stator 121 includes a stator core 1211, coils 1212, and insulators 1213. The stator core 1211 is made of a plurality of electromagnetic steel plates laminated in the X-axis direction. Here, the X-axis is the rotation axis of the motor 12. In this specification, the direction parallel to the X-axis is referred to as the axial direction. The insulators 1213 are components that sandwich the stator core 1211 (stator teeth) from both sides in the axial direction, and are members that insulate the stator core 1211 from the coils 1212. The coils 1212 are wound in a predetermined pattern around the stator core 1211 sandwiched between the insulators 1213.

[0014] In this embodiment, motor 12 is a three-phase motor, and coil 1212 includes a U-phase coil, a V-phase coil, and a plurality of W-phase coil wires. Furthermore, motor 12 according to this embodiment is electrically connected to control circuit 13 by a Y connection. Therefore, coil 1212 has wiring corresponding to each of the U-phase, V-phase, W-phase, and neutral point, and each wiring is electrically connected to control circuit 13.

[0015] In this embodiment, a plurality of bus bars 110 are present between the coil 1212 and the control circuit 13, the coil 1212 is electrically connected to the plurality of bus bars 110, and some of the plurality of bus bars 110 are further connected to the control circuit 13. With this configuration, the coil 1212 and the control circuit 13 are electrically connected.

[0016] (2) Busbar holder configuration The plurality of bus bars 110 are present between the coil 1212 and the control circuit 13 and electrically connect the two. For this reason, in this embodiment, a bus bar holder 100 that holds the plurality of bus bars is attached between the coil 1212 and the control circuit 13.

[0017] FIG. 3 is a perspective view showing the busbar 110 and the busbar holder 100, and FIG. 4 is a view showing the busbar 110 and the busbar holder 100 as viewed in the axial direction. Note that in FIGS. 3 and 4, the busbars 110 are distinguished by what they are connected to. That is, in FIGS. 3 and 4, the busbar 110 to which the U-phase coil 1212 is electrically connected is represented as busbar 110u, and the busbar 110 to which the V-phase coil 1212 is electrically connected is represented as busbar 110v. Also, in FIGS. 3 and 4, the busbar 110 to which the W-phase coil 1212 is electrically connected is represented as busbar 110w, and the busbar 110 to which the neutral point is electrically connected is represented as busbar 110n.

[0018] Each of the busbars 110u, 110v, 110w, and 110n has a shape that includes end portions 111u, 111v, 111w, and 111n that are connected to the control circuit 13, and a shape that does not include these end portions. Each of the busbars 110u, 110v, 110w, and 110n has a U-shaped curved joint portion (e.g., reference numeral 112 shown in FIGS. 3 and 4), and the joint portion is bent with the wiring extending from the coil 1212 sandwiched therebetween, and the wiring is joined by welding or the like. FIG. 5 is a perspective view showing the busbar 110 and the busbar holder 100 together with the stator 121, and shows a state in which the wiring 1212a extending from the coil 1212 is sandwiched and joined by the joint portion 112.

[0019] There are one or two bus bars 110 at the same potential. For example, there is one bus bar 110n, but two bus bars 110u, 110v, and 110w. A portion of bus bar 110 is housed in bus bar holder 100, and another portion is exposed from bus bar holder 100.

[0020] The bus bar holder 100 includes an annular holder body 101, bosses 102, and recesses 103. In Figures 3 and 4, only some of the bosses 102 and recesses 103 that exist are indicated by reference numerals.

[0021] The holder body 101 is an annular part centered on point O, which is the rotation axis of the motor 12 shown in Fig. 4. When viewed along the axial direction, the holder body 101 is a part that exists in the range from a circumference of radius Rmin to a circumference of radius Rmax centered on point O, and its axial height H (see Fig. 3) is constant.

[0022] In this specification, in the diameter of an arbitrary circle centered at point O shown in Fig. 4, the direction starting from point O and moving away from point O is referred to as the radially outward direction, and the direction toward point O in the arbitrary diameter is referred to as the radially inward direction. In addition, the direction along the circumference of the circle centered at point O is referred to as the circumferential direction.

[0023] The bus bar 110 is accommodated in the holder main body 101. In this embodiment, the holder main body 101 is molded by insert molding including the bus bar 110, so that the bus bar 110 is accommodated in the holder main body 101. In this embodiment, the holder main body 101 is made of resin.

[0024] 6A to 6C are perspective views showing bus bar 110. FIG. 6A shows bus bar 110u that does not have end portion 111u. FIG. 6B shows bus bar 110v that does not have end portion 111v. FIG. 6C shows bus bar 110n. In this embodiment, bus bar 110 is a plate-like member that is bent at multiple points to have a three-dimensional structure.

[0025] 6A to 6C, busbar 110 has main bodies 113u, 113v, and 113n extending in the circumferential direction. Main bodies 113u, 113v, and 113n have a constant axial thickness and a constant radial width. That is, main bodies 113u, 113v, and 113n are formed over a predetermined circumferential length with a constant radial width. Therefore, main bodies 113u, 113v, and 113n are arc-shaped portions.

[0026] The busbar 110 also has outer protrusions 114 that protrude radially outward from the main body. In FIGS. 6A to 6C, the outer protrusions 114 that protrude radially outward from the main bodies 113u, 113v, and 113n are shown as outer protrusions 114u, 114v, and 114n, respectively. The outer protrusions 114u, 114v, and 114n extend radially outward so as to reach a position radially outward beyond the outer circumferential surface of the ring formed by the holder main body 101. In other words, when the busbar 110 is housed in the holder main body 101, the outer protrusions 114 protrude radially outward beyond the outer periphery of the holder main body 101.

[0027] The outer protrusions 114 are configured so that their radially outer ends are bent vertically toward the opposite side from the motor 12, i.e., the control circuit 13 side, and extend in a direction parallel to the axial direction. In the bus bars 110u, 110v shown in Figures 6A and 6B, outer protrusions 114u, 114v are formed at both circumferential ends of the main bodies 113u, 113v. The ends of the outer protrusions 114u, 114v form U-shaped joints 112.

[0028] 6C, a bus bar 110n has four outer protrusions 114n, each of which is formed at one end of a main body 113n in the circumferential direction. The three outer protrusions 114n have U-shaped joints 112 at their tips, and the remaining outer protrusion 114n has an end 111n that is inserted into a through-hole in a control board 131.

[0029] Furthermore, bus bar 110 has inner protrusions 115 that protrude radially inward from the main body. In Figures 6A to 6C, inner protrusions 115 that protrude radially inward from main bodies 113u, 113v, and 113n are shown as inner protrusions 115u, 115v, and 115n, respectively.

[0030] 6A and 6B, inner protrusions 115u and 115v are formed on main bodies 113u and 113v, protruding radially inward from two positions. Bus bar 110n shown in Fig. 6C has inner protrusions 115n that protrude radially inward from four positions on main body 113n.

[0031] In this embodiment, inner protrusion 115 is used to hold bus bar 110 without moving it within a mold when holder main body 101 is molded by insert molding. That is, holder main body 101 is molded by injecting resin into a mold, and by holding bus bar 110 in the mold in advance, bus bar 110 and holder main body 101 are molded integrally.

[0032] In this embodiment, in order to hold the busbars 110 within the mold, the mold is configured to sandwich the inward protruding portions 115 of the busbars 110. That is, in this embodiment, the mold is divided into two in the axial direction of the holder main body 101, and by joining the molds from both sides in the axial direction, a space for molding the holder main body 101 is formed within the mold. Then, by sandwiching the inward protruding portions 115 of each busbar 110 from both sides in the axial direction, the mold is configured to hold the busbars 110 so that they do not move within the mold.

[0033] Because the inward protruding portion 115 is sandwiched between molds during molding, it is not housed in the holder main body 101 after molding, but is exposed radially inward from the inner circumferential surface, which is the radially inner surface of the holder main body 101. This exposed portion is called the exposed portion. In Figures 3 and 4, the portion of the inward protruding portion 115 that is exposed radially inward is called exposed portion 116, and a portion of this is shown.

[0034] A boss 102 is formed on the outer peripheral surface, which is the radially outer surface of holder main body 101. Boss 102 is a portion that protrudes from the outer peripheral surface and covers a portion of outer protrusion 114 of bus bar 110. In other words, outer protrusion 114 of bus bar 110 is not exposed to the outside of holder main body 101 from the outer peripheral surface of holder main body 101, but passes through boss 102 and is exposed radially outward from the radially outer end of boss 102.

[0035] Because the holder body 101 is made of resin, the bus bars 110 housed inside the holder body 101 are insulated from each other by the holder body 101. However, a relatively high voltage, such as 800 V, is applied to the motor 12 according to this embodiment. When a high voltage is applied in this manner, if the bus bars 110 are exposed to the outside of the holder body 101, it becomes necessary to ensure insulation so as to prevent conduction through the surface of the holder body 101.

[0036] That is, the distance on the surface of the holder body 101, i.e., the creepage distance, between the bus bars 110 exposed to the outside of the holder body 101 needs to be equal to or greater than a predetermined value according to the applied voltage. In this embodiment, the outer protrusions 114 exposed on the outer peripheral surface of the holder body 101 are covered by the bosses 102. When the bosses 102 are present, the creepage distance becomes longer compared to the outer peripheral surface without the bosses 102, and in this embodiment, the bosses 102 ensure a sufficient creepage distance.

[0037] On the other hand, there are no bosses on the inner peripheral surface of the holder main body 101. Therefore, in this embodiment, recesses 103 are formed to ensure insulation between the exposed portions 116 exposed on the inner peripheral surface side. The recesses 103 are grooves formed between the exposed portions 116 adjacent in the circumferential direction, and the grooves are formed along the axial direction of the holder main body 101 over the entire axial length.

[0038] According to the above configuration, the distance along the inner circumferential surface between adjacent exposed portions 116 is increased compared to when no recesses 103 are formed on the inner circumferential surface of the holder main body 101. Therefore, the creepage distance between the exposed portions 116 can be made longer compared to when no recesses 103 are formed.

[0039] Furthermore, since the recess 103 is formed along the axial length of the holder body 101 over the entire axial length, the exposed portion 116 may be exposed at any axial position on the inner peripheral surface of the holder body 101. Therefore, even if the exposed portion 116 is exposed at any axial position by simply forming a groove over the entire axial length, the creeping distance between adjacent exposed portions 116 can be made longer than when the recess 103 is not formed.

[0040] As described above, when the recess 103 according to this embodiment is present, the creepage distance becomes longer compared to when the recess 103 is not present. Therefore, the recess 103 corresponds to a processed portion that makes the creepage distance longer compared to when the processing for forming the recess 103 (integral processing during insert molding in this embodiment) is not performed.

[0041] In this embodiment, the recesses 103 increase the creepage distance compared to when the recesses 103 are not present, thereby ensuring insulation between adjacent exposed portions 116. For this reason, the recesses 103 are always provided between the exposed portions 116 of the bus bars 110 to which different potentials are applied. The width (circumferential length) and depth (radial length) of the recesses 103 are specified in advance so as to ensure the minimum creepage distance according to the potential difference of the exposed portions 116, and the shapes of all the recesses 103 are determined so that the creepage distance is equal to or greater than the minimum creepage distance.

[0042] In this embodiment, since the depth of all recesses 103 is constant, a minimum width of recesses 103 is defined, and all recesses 103 have a width equal to or greater than this minimum width. In Figures 3 and 4, recesses 103 with a minimum width are shown as recesses 103a.

[0043] As described above, the width of the recess 103 is configured to be equal to or greater than the minimum width, but in this embodiment, the recess 103 is formed between adjacent exposed portions 116 in all exposed portions 116, including exposed portions 116 of adjacent bus bars 110 that have the same potential. Therefore, the amount of resin used in the holder body 101 can be reduced compared to a configuration in which the recess 103 is not formed between some of the exposed portions 116.

[0044] Furthermore, in this embodiment, the width of the recess 103 increases as the circumferential distance between adjacent exposed portions 116 increases. In FIG. 4, there are multiple recesses 103 with different circumferential widths, but recess 103a has the smallest width and recess 103b has the largest width. By configuring the recess 103 so that the width increases as the circumferential distance between adjacent exposed portions 116 increases, the amount of resin used in the holder body 101 can be reduced compared to when the width of the recess 103 is constant and minimum.

[0045] (3) Other embodiments The above embodiment is one example of how the present invention can be implemented, and various other embodiments are possible. For example, the bus bar holder may be used in devices other than electric water pumps as long as it holds bus bars that electrically connect a motor and a control circuit. Furthermore, the shapes of the bus bars and bus bar holder are not limited to the configurations shown in FIGS. 3 and 4 and may be variously configured.

[0046] The recesses 103 serving as processed portions may have any structure as long as the creepage distance between the exposed portions 116 is longer than when the recesses 103 are not present. Therefore, the processed portions may have various shapes. Examples of such processed portions include protrusions formed between the exposed portions. That is, the inner circumferential surface of the holder body 101 between the exposed portions 116 may have protrusions that protrude radially inward, and the protrusions may be configured to increase the creepage distance compared to when the protrusions are not present. The shape of the protrusions is not limited, and may be a rectangular or semicircular cross section perpendicular to the axial direction, and various other configurations may be employed. Such a configuration can also increase the likelihood of ensuring insulation between the busbars compared to when the processed portions are not present.

[0047] The bus bar holder only needs to be able to hold multiple bus bars that are electrically connected to the coils of the motor and the control circuit that controls the motor. Therefore, as long as the holder body is annular, the shape and size are not limited to the above-described configuration. Various configurations for holding the bus bars are also possible, and any configuration for holding the bus bars can be adopted as long as the exposed portions of the bus bars are exposed radially inward of the holder body.

[0048] The motor may be any motor in which the busbars can be set to different potentials by applying different potentials, and the type of motor is not limited. It is also preferable that a relatively high voltage be applied to the motor, to the extent that a creepage distance must be ensured by the processed portion. Such a voltage may be, for example, several hundred volts or more, such as 800 V. Furthermore, the motor's wiring is not limited to a Y-connection, and may be a Δ-connection or the like. The control circuit may be any circuit that controls the motor, and the type of control circuit is not limited.

[0049] The holder body is an annular member that accommodates a plurality of bus bars. At least a portion of the bus bars may be accommodated in the holder body. The manner in which the bus bars are accommodated is not limited to insert molding as in the above-described embodiment.

[0050] If the holder body is an annular member, it is possible to arrange members other than the bus bar holder radially inside the holder body. For example, it is possible to arrange the rotating shaft of a motor or other members radially inside the holder body without interfering with the holder body, making it easy to arrange the motor and bus bar holder adjacent to each other.

[0051] The holder body may be annular. That is, the holder body may be shaped like a ring. Therefore, the axial length of the ring and the shape of the outer peripheral surface are not limited, and the shape of the inner peripheral surface is not limited as long as a processed portion is formed. At least a portion of a member other than the busbar may be housed in the busbar holder. Also, a portion of the ring shape in the circumferential direction may be interrupted.

[0052] The busbar is a conductor member electrically connected to the coil and control circuit of the motor. That is, the busbar electrically connects the coil and the control circuit. Note that the busbar preferably has a cross-sectional area corresponding to the voltage and current so that it can withstand high voltages and currents. The busbar also has an exposed portion on the inner circumferential surface, which is the radially inner surface of the holder body, that is exposed toward the radially inner side of the holder body. That is, a portion of the busbar is exposed on the inner circumferential surface of the holder body. The processed portion is formed to provide insulation between the exposed portions.

[0053] In the above-described embodiment, the exposed portion is exposed on the inner circumferential surface so as to have a surface parallel to a direction perpendicular to the axial direction of the holder main body, but the form of the exposed portion is not limited to this. When bus bars with different potentials are exposed on the inner circumferential surface in any state, they become exposed portions.

[0054] The busbars may also be exposed on the outer peripheral surface of the holder body. In the above-described embodiment, the busbar holder covers the exposed portions of the busbars on the outer peripheral surface and has boss-like portions that protrude radially outward, so no processing is performed to ensure a creepage distance. Of course, if it is necessary to ensure a creepage distance in order to insulate the exposed portions on the outer peripheral surface from each other, a processed portion may be formed on the outer peripheral surface.

[0055] The processed portion is formed on the inner peripheral surface of the holder body between the exposed portions, and it is sufficient if the processed portion can make the creepage distance longer than when the processed portion is not formed. In other words, if the processed portion makes the length of the surface of the holder body between the exposed portions, i.e., the creepage distance, longer than when the processed portion is not formed, it is more likely that insulation will be ensured.

[0056] Of course, the shape of the processed portion may be determined so that the creepage distance ensures an insulation distance depending on the maximum potential difference generated between adjacent bus bars, etc. For example, a configuration may be adopted in which the minimum creepage distance between adjacent bus bars is determined, and the shape of the processed portion, such as the depth of the recesses and the height of the protrusions, is determined so that the minimum creepage distance can be ensured. Furthermore, the length of the minimum creepage distance may be configured to increase as the maximum potential difference generated between adjacent bus bars increases.

[0057] The recessed portion may be a groove formed on the inner peripheral surface, and the shape of the recessed portion is not limited. For example, the recessed portion may have a shape in which the width or depth varies. [Explanation of symbols]

[0058] 1...electric water pump, 11...pump, 12...motor, 13...control circuit, 21...body housing, 22...driver housing, 100...busbar holder, 101...holder body, 102...boss, 103...recess, 103a...recess, 103b...recess, 110, 110n, 110u, 110v, 110w, 112...joint, 113n, 113u, 113v, 114, 114n, 114u, 114v, 115, 115n, 115u, 115v, 116...exposed portion, 121...stator, 122...rotor, 123...insulator, 131...control board, 200...holder, 210...terminal guide, 1211...stator core, 1212...coil, 1212a...wiring, 1213...insulator

Claims

1. A bus bar holder that holds a plurality of bus bars that are electrically connected to a coil provided in a motor and to a control circuit that controls the motor, an annular holder body that accommodates the plurality of bus bars; the bus bar has an exposed portion that is exposed toward the radially inner side of the holder main body on an inner circumferential surface that is a radially inner surface of the holder main body, The inner circumferential surface has a processed portion formed between the exposed portions, which increases the creepage distance compared to a case where the processed portion is not processed. Busbar holder.

2. The processed portion is a recess formed between the exposed portions. The bus bar holder according to claim 1 .

3. The recess is formed on the inner circumferential surface along the axial direction of the holder body. The bus bar holder according to claim 2 .

4. The processed portion is a convex portion formed between the front exposed portions. The bus bar holder according to claim 1 .

Images