Current detection device

Abstract

This current detection device is attached to a motor unit including both a housing that accommodates the motor, and a busbar that is electrically connected to the motor and attached to the outer wall of the housing, said current detection device being for detecting an alternating current flowing through the busbar. The current detection device includes: a control substrate; a magnetic detection element that is supported by the control substrate in a state in which the magnetic detection element is disposed so as to protrude from the main surface of the control substrate, that is electrically connected to the control substrate, and that outputs, to the control substrate, a detection signal based on a magnetic field; and a sealing member which seals the magnetic detection element, which is connected to the main surface of the control substrate, and the longitudinal direction of which is the direction of protrusion from the main surface. The control substrate is fixed to the housing such that the busbar is sandwiched between the control substrate and the housing and such that the main surface of the control substrate faces the busbar. The sealing member penetrates through a through-hole formed in the busbar and is also fitted into a recessed portion formed in the housing. The magnetic detection element is disposed at a position facing the inner side surface of the through-hole.

Description

Current detection device

[0001] The present invention relates to a current detection device.

[0002] JP2022-88065A discloses a current detection device that detects AC current flowing through a busbar by detecting a magnetic field generated around the busbar, and the current detection device includes a control board including a magnetic detection element and a sensor housing that is molded integrally with the busbar. The control board is fitted into guide recesses and protrusions formed on the sensor housing, and the relative position of the control board to the busbar is defined, thereby suppressing changes in the detection accuracy of AC current.

[0003] However, in JP2022-88065A, the bus bar needs to be integrally molded with the sensor housing using a resin mold or the like, which means that when connecting the inverter and motor within the motor unit with the bus bar, the number of connection points increases, reducing the freedom of shape design and increasing assembly costs and parts costs.

[0004] Therefore, an object of the present invention is to provide a current detection device that suppresses changes in the detection accuracy of AC current flowing through a bus bar, improves the freedom of shape design, and further reduces assembly costs and component costs.

[0005] According to one aspect of the present invention, there is provided a current detection device that is attached to a motor unit having a housing that accommodates a motor and a busbar that is electrically connected to the motor and attached to an outer wall of the housing, and that detects an AC current flowing through the busbar. The current detection device includes a control board, a magnetic detection element that is supported on the control board and disposed so as to protrude from a main surface of the control board, is electrically connected to the control board, and outputs a detection signal based on a magnetic field to the control board, and a sealing member that seals the magnetic detection element and is connected to the main surface of the control board and has a longitudinal direction that protrudes from the main surface. The control board and the housing sandwich the busbar and are fixed to the housing so that the main surface faces the busbar, the sealing member passes through a through hole formed in the busbar and is fitted into a recess formed in the housing, and the magnetic detection element is disposed in a position facing the inner side surface of the through hole.

[0006] FIG. 1 is a cross-sectional view of a current detection device according to a first embodiment. FIG. 2 is an exploded view of the current detection device according to the first embodiment. FIG. 3 is a bottom view (viewed from the arrow A in FIG. 2 ) of a control board constituting the current detection device according to the first embodiment. FIG. 4 is a plan view (viewed from the arrow B in FIG. 2 ) of a bus bar. FIG. 5 is a view (viewed from the arrow B in FIG. 2 ) showing a state in which a sealing member of the current detection device is inserted into a through-hole of the bus bar. FIG. 6 is a diagram showing an error in a detection signal that appears when an error in mounting the magnetic detection element occurs in the normal direction (Z direction) of the main surface of the bus bar. FIG. 7 is a diagram showing an error in a detection signal that appears when an error in mounting the magnetic detection element occurs in the planar directions (X direction and Y direction) of the main surface of the bus bar. FIG. 8 is a cross-sectional view of a current detection device according to a second embodiment. FIG. 9 is a side view of a conductive spring constituting the current detection device according to the second embodiment. FIG. 10 is a plan view of a conductive spring constituting the current detection device according to the second embodiment. FIG. 11 is a cross-sectional view of a current detection device according to a third embodiment. 12 and 13 are diagrams illustrating a first and second concave-convex pattern on the tip of the sealing member of the current detection device of the third embodiment.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] [First embodiment] Fig. 1 is a cross-sectional view of a current detection device 100 according to a first embodiment. Fig. 2 is an exploded view of the current detection device 100 according to the first embodiment. Fig. 3 is a bottom view (viewed from the direction of arrow A in Fig. 2) of a control board 1 constituting the current detection device 100 according to the first embodiment. Fig. 4 is a plan view (viewed from the direction of arrow B in Fig. 2) of a bus bar 7. Fig. 5 is a view (viewed from the direction of arrow B in Fig. 2) showing a state in which a sealing member 3 of the current detection device 100 is inserted into a through-hole 72 of the bus bar 7. In the drawings, the X-axis, Y-axis, and Z-axis are assumed to be orthogonal to one another.

[0009] The motor unit to which the current detection device 100 of the first embodiment is applied includes a housing 6 that accommodates a motor (not shown), and a bus bar 7 that is electrically connected to the motor (stator) and attached to the outer wall of the housing 6.

[0010] Insulating second fasteners 8 are attached to the outer wall of the housing 6 in two locations, and the bus bar 7 is attached so as to span between the two second fasteners 8. Second screw holes 81 are formed in the upper surface of the second fastener 8, and second bolt holes 71 are formed in the bus bar 7 at positions facing the second screw holes 81. Second fastening bolts 82 are inserted through the second bolt holes 71 with the second bolt holes 71 communicating with the second screw holes 81, and the second fastening bolts 82 are screwed into the second screw holes 81, thereby fixing the bus bar 7 to the housing 6 while being insulated from the housing 6.

[0011] A through hole 72 is formed in the bus bar 7 at a position between the two second bolt holes 71, and a sealing member 3, which will be described later, is inserted into the through hole 72.

[0012] There are bus bars 7 for U-phase, V-phase and W-phase, all of which have the same configuration.

[0013] The current detection device 100 of the first embodiment is composed of a control board 1 , a magnetic detection element 2 , and a sealing member 3 .

[0014] The control board 1 is configured with a printed circuit board or the like, and is provided with wiring patterns, signal processing circuits, etc. as appropriate, and is also equipped with electronic components (not shown). The magnetic detection element 2 is disposed on the surface of the control board 1 facing the housing 6 (the surface on the -Z direction side) so as to be electrically connected to the wiring patterns, etc.

[0015] The magnetic detection element 2 includes a sensor portion 21 that detects magnetism (signal magnetic field) and a leg portion 22 that extends from the sensor portion 21 toward the control board 1, connects to the control board 1, and electrically connects the sensor portion 21 to the wiring pattern on the control board 1 side.

[0016] The sensor unit 21 is a coreless type that outputs a detection signal in response to a signal magnetic field that passes through it, and is configured to include, for example, a Hall element, a TMR (tunnel magneto-resistance) element, a GMR (giant magnetic resistance) element, an AMR (anisotropic magneto-resistance) element, etc. In Fig. 1 etc., the sensor unit 21 is arranged so that its thickness direction is oriented perpendicular (X direction or Y direction) to the thickness direction (Z direction) of the control board 1, but the orientation can be set arbitrarily.

[0017] The sealing member 3 is a resin material that seals the magnetic detection element 2. As the resin material, a resin having insulating properties and high thermal conductivity, such as high-density polyethylene or PPS (abbreviation of Polyphenylene Sulfide), is suitable.

[0018] The sealing member 3 is inserted into a through hole 72 formed in the bus bar 7 and fits into a recess 61 formed in the housing 6. More specifically, the sealing member 3 includes a base 31 connected to the control board 1, a tapered portion 33 that extends from the surface of the base 31 facing the housing 6 in a direction toward the housing 6 (-Z direction) and fits into the through hole 72, and a tip portion 34 that extends from the tip of the tapered portion 33 further in a direction toward the housing 6 and fits into the recess 61.

[0019] The cross-sectional shapes of the base portion 31, the tapered portion 33, and the tip portion 34 are rectangular.

[0020] The surface of the base 31 facing the housing 6 and the portion outside the area connected to the tapered portion 33 is the flange portion 32, which is arranged parallel to the main surface of the busbar 7 (the surface normal to the +Z direction).

[0021] The cross-sectional shape (rectangular shape) at the connection position of the tapered portion 33 with the base 31 is set to be the same as or slightly smaller than the opening shape (rectangular shape) of the through hole 72, but becomes smaller as it approaches the tip 34.

[0022] The cross-sectional shape (rectangular shape) of the recess 61 is formed to be substantially the same as the cross-sectional shape (rectangular shape) of the tip portion 34 so that the tip portion 34 can be fitted into the recess 61 .

[0023] 3, the control board 1 is formed in a rectangular shape, and the magnetic detection element 2 and the sealing member 3 are disposed in the center thereof. In addition, first bolt holes 11 are formed in the corners of the rectangle of the control board 1.

[0024] When the sealing member 3 is fitted into the recess 61, a first fixing device 4 is positioned opposite the first bolt hole 11 of the control board 1 of the housing 6, and a first screw hole 41 is positioned opposite the first bolt hole 11 on the top surface of the first fixing device 4.

[0025] Then, with the first bolt hole 11 connected to the first screw hole 41, the first fixing bolt 42 is inserted through the first bolt hole 11 and the first fixing bolt 42 is screwed into the first screw hole 41, whereby the control board 1 is fixed to the housing 6 while being insulated from the housing 6, and the sealing member 3 is fixed to the housing 6 (recess 61) with the tip 34 of the sealing member 3 fitted into the recess 61.

[0026] In this case, the magnetic detection element 2 is positioned so that its main surface faces the inner side surface (inner wall) of the through hole 72 (both main surfaces of the magnetic detection element 2 simultaneously intersect the two planes formed by the two main surfaces of the bus bar 7), and so that its upper end protrudes in the +Z direction beyond the bus bar 7 and its lower end protrudes in the -Z direction beyond the bus bar 7.

[0027] 1 and other figures, the sealing member 3 (magnetic detection element 2) is fitted into the through-hole 72 at the connection position between the tapered portion 33 and the base portion 31. This fixes the relative position of the main surface of the bus bar 7 in the planar direction (X direction, Y direction), thereby reducing installation error in the planar direction.

[0028] Furthermore, the sealing member 3 (magnetic detection element 2) is configured so that the flange portion 32 contacts the main surface of the bus bar 7 (and the connection position of the tapered portion 33 with the base portion 31), and other portions do not contact the bus bar 7. This fixes the relative position and orientation of the sealing member 3 (magnetic detection element 2) to the bus bar 7 in the normal direction (Z direction), thereby reducing attachment errors of the sealing member 3 (magnetic detection element 2) to the bus bar 7 in the normal direction (Z direction) and orientation errors with respect to the normal direction (Z direction).

[0029] Furthermore, the tip 34 of the sealing member 3 (magnetic detection element 2) fits into the recess 61. This reduces changes in the relative position and orientation of the sealing member 3 (magnetic detection element 2) with respect to the bus bar 7 even when the sealing member 3 (magnetic detection element 2) is subjected to an external impact (acceleration).

[0030] Furthermore, since the tapered portion 33 is spaced apart from the inner side surface of the through hole 72 except for the joint position with the base portion 31, direct heat conduction from the through hole 72 to the side surface of the tapered portion 33 can be reduced.

[0031] 6 is a diagram showing an error in a detection signal that appears when an error in mounting the magnetic detection element 2 occurs in the normal direction (Z direction) of the main surface of the bus bar 7. Fig. 7 is a diagram showing an error in a detection signal that appears when an error in mounting the magnetic detection element 2 occurs in the planar directions (X direction, Y direction) of the main surface of the bus bar 7.

[0032] 6 , when the magnetic detection element 2 is placed at a reference position (X0, Y0, Z0) with no mounting error in the normal direction or the surface direction, and a predetermined AC signal is applied to the bus bar 7, the detection signal (S) detected by the magnetic detection element 2 is defined as a reference value (S0). If an installation error (Z) occurs in the normal direction (Z direction) of the magnetic detection element 2 to the main surface of the bus bar 7, the installation error (Z) and the detection signal (S) have a linear function correspondence. Therefore, the installation error (Z) can be uniquely determined by the difference between the detection signal (S) and the reference value (S0), and the installation error can be easily corrected.

[0033] 7 , if an attachment error occurs in the magnetic detection element 2 in the surface directions (X direction, Y direction) of the main surface of the busbar 7, the attachment error (X) and the detection signal (S), and the attachment error (Y) and the detection signal (Y) each have an upwardly convex quadratic function relationship. Therefore, if there is an attachment error (X) and an attachment error (Y) in the surface direction of the magnetic detection element 2, there are two solutions for the attachment error (X) relative to the detection signal (S) and two solutions for the attachment error (Y) relative to the detection signal (S). Therefore, the attachment error in the surface direction cannot be uniquely determined from the detection signal (S), and correcting the attachment error becomes difficult.

[0034] However, in this embodiment, as described above, the sealing member 3 sealing the magnetic detection element 2 is inserted into the through hole 72 formed in the bus bar 7, and then the sealing member 3 is fitted into the recess 61. This reduces the attachment error of the magnetic detection element 2 in the plane directions (X direction and Y direction) of the bus bar 7, and reduces the need for complicated correction work.

[0035] In this embodiment, the sealing member 3 connected to the control board 1 penetrates the bus bar 7, and the sealing member 3 is further fitted into the housing 6 having the recess 61. This allows the control board 1 (and the magnetic detection element 2) and the bus bar 7 to be positioned together, simplifying the assembly process. Furthermore, there is no need to provide a separate positioning mechanism for the control board 1, such as a locator, making it possible to achieve an inexpensive structure.

[0036] In this embodiment, the contact surface of the flange portion 32 with the busbar 7 and the contact surface (main surface) of the busbar 7 that contacts the flange portion 32 are arranged parallel to each other. This allows the relative position and orientation of the magnetic detection element 2 and the busbar 7 to be determined in a predetermined manner, thereby reducing deterioration in current detection accuracy caused by misalignment of the magnetic detection element 2 with respect to the busbar 7.

[0037] As described above, the detection signal (S) detected by the magnetic detection element 2 has a linear function characteristic with respect to the installation error (Z) in the normal direction of the bus bar 7, making it easy to correct the installation error. Therefore, the dimensions of the magnetic detection element 2 are set with priority given to reducing the positional deviation (variation) in the planar directions (X direction, Y direction), while also taking into account the positional deviation (variation) in the normal direction (Z direction).

[0038] Second Embodiment Fig. 8 is a cross-sectional view of a current detection device 100 according to a second embodiment. Fig. 9 is a side view of a conductive spring 5 constituting the current detection device 100 according to the second embodiment. Fig. 10 is a plan view of the conductive spring 5 constituting the current detection device 100 according to the second embodiment.

[0039] As shown in Figure 8, the current detection device 100 of the second embodiment has a control board 1 (first fixing device 4, first fixing bolt 42), magnetic detection element 2, and sealing member 3 that are configured in the same way as the first embodiment, and the housing 6 also has a recess 61 into which the tip portion 34 of the sealing member 3 is fitted.

[0040] In the second embodiment, the bus bar 7 is composed of two fixed bus bars 701 and a movable bus bar 702 .

[0041] The fixed bus bar 701 is attached (adhered) to the housing 6 via an insulator 73. The insulator 73 is formed, for example, from an insulating adhesive. The adhesive is applied to the outer wall of the housing 6 in a predetermined thickness following the shape of the main surface of the fixed bus bar 701, and the fixed bus bar 701 is attached to the housing 6 by placing the fixed bus bar 701 on the adhesive and allowing the adhesive to dry.

[0042] The movable bus bar 702 is separate from the two fixed bus bars 701, but has a through hole 72 like the bus bar 7 of the first embodiment, and is shaped so that when the sealing member 3 is inserted into the through hole 72 and fitted into the recess 61, one longitudinal end of the movable bus bar 702 can come into contact with one of the fixed bus bars 701, and the other longitudinal end of the movable bus bar 702 can come into contact with the other of the fixed bus bars 701.

[0043] One or more conductive springs 5 ​​are arranged on the fixed bus bar 701 at positions facing the movable bus bar 702 in the Z direction.

[0044] As shown in Figures 9 and 10, the conductive spring 5 includes a movable arm 51 that contacts the movable bus bar 702, and a support portion 52 that cantilevers the movable arm 51 and is arranged on the fixed bus bar 701 (which may also be arranged on the movable bus bar 702), both of which are made of a conductive material (metal).

[0045] One longitudinal end of the movable arm 51 is supported by the support portion 52 as a fixed end, and the other longitudinal end is a free end that contacts the fixed bus bar 701 .

[0046] In the second embodiment, the control board 1 is fastened with the first fixing bolts 42 while the sealing member 3 is inserted into the through-hole 72 and fitted into the recess 61, thereby fixing the control board 1 and the sealing member 3 (magnetic detection element 2) to the housing 6. At this time, the conductive springs 5 ​​come into contact with the fixed bus bar 701 and the movable bus bar 702 simultaneously, thereby electrically connecting the fixed bus bar 701 and the movable bus bar 702.

[0047] Furthermore, the force exerted when the first fixing bolt 42 is fastened is transmitted to the conductive spring 5 (movable arm 51) via the flange portion 32 and the movable bus bar 702, pressing the conductive spring 5 in the -Z direction. This generates a restoring force in the +Z direction in the conductive spring 5, which is applied to the movable bus bar 702 (and the fixed bus bar 701). This reduces poor contact between the fixed bus bar 701 and the conductive spring 5 (support portion 52) and between the movable bus bar 702 and the conductive spring 5 (movable arm 51).

[0048] In addition, the conductive spring 5 can be of any shape other than those shown in Figures 9 and 10, as long as it can be arranged between the fixed bus bar 701 and the movable bus bar 702 and can generate a restoring force (elastic force) in the opposite direction to the pressing force from the fixed bus bar 701.

[0049] The configuration of the second embodiment eliminates the need for the second fixing device 8 and second fixing bolt 82 of the first embodiment, which in turn reduces the number of parts, thereby reducing costs and the height of the motor unit (the distance between the housing 6 and the control board 1).

[0050] [Third embodiment] Fig. 11 is a cross-sectional view of a current detection device 100 according to a third embodiment. Fig. 12 is a diagram showing a first concave-convex pattern on the tip of the sealing member 3 (tip portion 34) of the current detection device 100 according to the third embodiment. Fig. 13 is a diagram showing a second concave-convex pattern on the tip of the sealing member 3 (tip portion 34) of the current detection device 100 according to the third embodiment.

[0051] Compared to the second embodiment, the current detection device 100 of the third embodiment is configured to be able to reduce the influence of heat from the busbar 7 on the magnetic detection element 2. Furthermore, compared to the second embodiment, the current detection device 100 of the third embodiment is configured to be able to particularly reduce the influence of heat from the busbar 7 on the magnetic detection element 2 when a flow path 9 for cooling water that cools the motor (stator) is arranged near the outer wall of the housing 6.

[0052] In the third embodiment, the sealing member 3 includes a first sealing portion 35 that seals the magnetic detection element 2 and a second sealing portion 36 that seals the outer periphery of the first sealing portion 35. The first sealing portion 35 is formed to include the inner periphery of the base portion 31, the inner periphery of the tapered portion 33, and the inner periphery of the tip portion 34, while the second sealing portion 36 is formed to include the outer periphery of the base portion 31, the flange portion 32, the outer periphery of the tapered portion 33, and the outer periphery of the tip portion 34. The first sealing portion 35 and the second sealing portion 36 each contact the control board 1 and the bottom surface of the recess 61.

[0053] The second sealing portion 36 is formed by filling a filler such as Grice fiber from the outer periphery of the sealing member 3. As a result, the thermal conductivity of the second sealing portion 36 is set to be lower than the thermal conductivity of the first sealing portion 35. In addition, the rigidity (Young's modulus) of the second sealing portion 36 is set to be higher than the rigidity of the first sealing portion 35.

[0054] Because an alternating current flows through the movable bus bar 702 (bus bar 7) having the through hole 72, the temperature tends to rise as the cross-sectional area becomes smaller. However, in the third embodiment, the second sealing portion 36 that seals the outer periphery of the first sealing portion 35 (magnetic detection element 2) is made of a low-thermal-conductivity material that abuts against the control board 1, the movable bus bar 702 (bus bar 7), and the housing 6. This insulates the periphery of the magnetic detection element 2, thereby reducing the amount of heat that the magnetic detection element 2 receives from the movable bus bar 702 (bus bar 7).

[0055] Furthermore, since the rigidity of the second sealing portion 36 is higher than that of the first sealing portion 35, the mounting accuracy in the planar and normal directions between the flange portion 32, which is part of the second sealing portion 36, and the movable bus bar 702 (bus bar 7) can be improved.

[0056] As shown in the enlarged view of Figure 11, a second uneven structure (second recess 351) (which may be convex) is arranged at the tip of the first sealing portion 35 (tip portion 34), and a second uneven structure (protrusion 611) (which may be concave) is arranged on the bottom surface of the recess 61.

[0057] The portion of the first sealing portion 35 (tip portion 34) other than the second recess 351 at the tip abuts against the bottom surface of the recess 61, and the protrusion 611 fits into the second recess 351 of the first sealing portion 35. The bottom surface of the recess 61 is close to the cooling water flow path 9 (the arrows in the flow path 9 indicate the flow direction of the cooling water). The first uneven structure (the second recess 351 and the portion of the first sealing portion 35 other than the second recess 351 at the tip) and the second uneven structure (the protrusion 611 and the portion of the bottom surface of the recess 61 other than the protrusion 611) serve as heat dissipation fins for the first sealing portion 35, and efficiently extract heat from the first uneven structure and the second uneven structure and release it into the cooling water, thereby efficiently reducing the influence of heat from the movable bus bar 702 (bus bar 7) on the magnetic detection element 2.

[0058] The second recess 351 formed at the tip of the first sealing portion 35 may be configured to have a groove shape extending in the Y direction and a plurality of recesses may be arranged at equal intervals in the X direction, as shown in Fig. 12. Correspondingly, the protrusions 611 (not shown in Fig. 12) formed on the bottom surface of the recess 61 of the housing 6 may be configured to have a ridge shape extending in the Y direction and a plurality of protrusions may be arranged at equal intervals in the X direction.

[0059] 13, the second recess 351 may be configured as a rectangular (or elliptical) ring-shaped groove, with a plurality of second recesses 351 arranged concentrically. Correspondingly, the protrusion 611 (not shown in FIG. 13) may be configured as a rectangular (or elliptical) ring-shaped ridge, with a plurality of second recesses 351 arranged concentrically.

[0060] [Effects of this embodiment] The current detection device 100 of this embodiment is attached to a motor unit (not shown) having a housing 6 that accommodates a motor (not shown) and a bus bar 7 that is electrically connected to the motor (not shown) and attached to the outer wall of the housing, and detects an AC current flowing through the bus bar 7. The current detection device 100 includes a control board 1, a magnetic detection element 2 that is supported on the control board 1 in a state where it protrudes from the main surface of the control board 1 and is electrically connected to the control board 1, and outputs a detection signal (S) based on a magnetic field to the control board 1, and a sealing member 3 that seals the magnetic detection element 2 and is connected to the main surface of the control board 1 and has a longitudinal direction that protrudes from the main surface. The control board 1 sandwiches the bus bar 7 together with the housing 6 and is fixed to the housing 6 with its main surface facing the bus bar 7. The sealing member 3 passes through a through hole 72 formed in the bus bar 7 and further fits into a recess 61 formed in the housing 6. The magnetic detection element 2 is positioned facing the inner side surface of the through hole 72.

[0061] With the above configuration, the sealing member 3 connected to the control board 1 penetrates the bus bar 7 and fits into the housing 6 having the recess 61, allowing the control board 1 (and the magnetic detection element 2) and the bus bar 7 to be positioned together, simplifying the assembly process. Furthermore, by forming the through-hole 72 in the bus bar 7 and the recess 61 in the housing 6, the sealing member 3 (magnetic detection element 2) and the control board 1 can be positioned relative to the bus bar 7, improving the flexibility of the shape design within the motor unit. Furthermore, since there is no need to provide a separate positioning mechanism for the control board 1, such as a locator, an inexpensive structure can be achieved. As described above, the current detection device 100 suppresses changes in the detection accuracy of the AC current flowing through the bus bar 7, improves the flexibility of the shape design, and further reduces assembly and component costs.

[0062] In this embodiment, the busbars 7 include a pair of fixed busbars 701 fixed to the outer wall of the housing 6 via insulators 73, and a movable busbar 702 that is separated from the pair of fixed busbars 701 and has a through hole 72, and that can simultaneously come into contact with the pair of fixed busbars 701 when the sealing member 3 (tapered portion 33, tip portion 34) is inserted into the through hole 72 and fitted into the recess 61, and the control board 1 is fixed to the housing 6 via fastening means (first bolt hole 11, first fixing device 4, first screw hole 41, first fixing bolt 42), and a conductive busbar that generates a restoring force by receiving a force is provided at the contact position between the movable busbar 702 and the pair of fixed busbars 701. The screw 5 is arranged, and the sealing member 3 has a flange portion 32 that abuts the main surface of the movable bus bar 702. When the control board 1 is fixed to the housing by fastening means (first bolt hole 11, first fixing device 4, first screw hole 41, first fixing bolt 42) with the sealing member 3 (tip portion 34) fitted into the recess 61, the fastening means (first bolt hole 11, first fixing device 4, first screw hole 41, first fixing bolt 42) presses against the conductive spring 5 via the flange portion 32 and the movable bus bar 702, applying a restoring force to the pair of fixed bus bars 701 and the movable bus bar 702, and the pair of fixed bus bars 701 and the movable bus bar 702 are electrically connected via the conductive spring 5.

[0063] With the above configuration, components for fixing the movable bus bar 702 (second fixing device 8, second fixing bolt 82, etc.) are not required, which in turn reduces the number of parts, thereby reducing costs and the height of the motor unit (the distance between the housing 6 and the control board 1).

[0064] In this embodiment, the contact surface of the flange portion 32 with the movable bus bar 702 is arranged parallel to the contact surface of the movable bus bar 702 with the flange portion 32 .

[0065] With the above configuration, the relative position and orientation between the magnetic detection element 2 and the movable bus bar 702 (bus bar 7) are determined to be predetermined relative positions and orientations, thereby reducing deterioration in current detection accuracy caused by misalignment between the magnetic detection element 2 and the movable bus bar 702 (bus bar 7).

[0066] In this embodiment, the sealing member 3 includes a first sealing portion 35 that seals the magnetic detection element 2 and a second sealing portion 36 that seals the outer periphery of the first sealing portion 35, and the thermal conductivity of the second sealing portion 36 is set to be lower than the thermal conductivity of the first sealing portion 35.

[0067] With the above configuration, the second sealing portion 36 that seals the outer periphery of the first sealing portion 35 (magnetic detection element 2) is made of a low thermal conductive material that abuts against the control board 1, the movable bus bar 702 (bus bar 7), and the housing 6, so that the area around the magnetic detection element 2 is insulated and the amount of heat that the magnetic detection element 2 receives from the movable bus bar 702 (bus bar 7) can be reduced.

[0068] In this embodiment, the first sealing portion 35 has a first uneven structure (second recess 351) that contacts the bottom surface of the recess 61, and the bottom surface of the recess 61 has a second uneven structure (protrusion 611) that can fit into the first uneven structure (second recess 351), and the first sealing portion 35 and the recess 61 are in contact with each other such that the first uneven structure (second recess 351) and the second uneven structure (protrusion 611) fit into each other.

[0069] With the above configuration, the first uneven structure (the second recess 351 and the portion other than the second recess 351 at the tip of the first sealing portion 35) and the second uneven structure (the convex portion 611 and the portion other than the convex portion 611 on the bottom surface of the recess 61) serve as heat dissipation fins in the first sealing portion 35, and efficiently extract heat received from the movable bus bar 702 (bus bar 7) from the first uneven structure and the second uneven structure and release it into the cooling water, thereby efficiently reducing the influence of heat from the movable bus bar 702 (bus bar 7) on the magnetic detection element 2.

[0070] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A current detection device attached to a motor unit having a housing that accommodates a motor, and a bus bar that is electrically connected to the motor and attached to an outer wall of the housing, and that detects an alternating current flowing through the bus bar, the current detection device including: a control board; a magnetic detection element that is supported on the control board in a state that it protrudes from a main surface of the control board and is electrically connected to the control board, and that outputs a detection signal based on a magnetic field to the control board; and a sealing member that seals the magnetic detection element and is connected to the main surface of the control board, with the direction that it protrudes from the main surface being its longitudinal direction, wherein the control board sandwiches the bus bar together with the housing and is fixed to the housing so that the main surface faces the bus bar, the sealing member passes through a through hole formed in the bus bar and further fits into a recess formed in the housing, and the magnetic detection element is positioned to face the inner side surface of the through hole.

2. The current detection device according to claim 1, wherein the bus bars include: a pair of fixed bus bars fixed to the outer wall of the housing via an insulator; and a movable bus bar that is separated from the pair of fixed bus bars and has the through hole, and that can simultaneously contact the pair of fixed bus bars when the sealing member is inserted through the through hole and fitted into the recess; the control board is fixed to the housing via fastening means; conductive springs that generate a restoring force when subjected to a force are arranged at the contact position between the movable bus bar and the pair of fixed bus bars; the sealing member has flange portions that abut against a main surface of the movable bus bar; and when the control board is fixed to the housing by the fastening means with the sealing member fitted into the recess, the fastening means presses the conductive spring via the flange portions and the movable bus bar, thereby applying the restoring force to the pair of fixed bus bars and the movable bus bar, and the pair of fixed bus bars and the movable bus bar are electrically connected via the conductive spring.

3. The current detection device according to claim 2, wherein the contact surface of the flange portion with the movable bus bar is arranged parallel to the contact surface of the movable bus bar with the flange portion.

4. A current detection device as described in claim 3, wherein the sealing member includes a first sealing portion that seals the magnetic detection element and a second sealing portion that seals the outer periphery of the first sealing portion, and the thermal conductivity of the second sealing portion is set to be lower than the thermal conductivity of the first sealing portion.

5. A current detection device as described in claim 4, wherein the first sealing portion has a first uneven structure that contacts the bottom surface of the recess, the bottom surface of the recess has a second uneven structure that can fit into the first uneven structure, and the first sealing portion and the recess contact each other in a manner where the first uneven structure and the second uneven structure fit into each other.

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