JP2019180218A - On-vehicle motor compressor - Google Patents

Abstract

To provide an on-vehicle motor compressor having a filter circuit with an excellent heat dissipation.SOLUTION: A common mode choke coil 34 comprises: an annular core 50; a first winding 60 wound to the core 50: a second winding 61 which is wound and opposite to the core 50 while being separated from the first winding 60; and an annular and thin film-like metal thin film 70 which covers the core 50 while overlapping the first and second windings 60 and 61. In the metal thin film 70, both portions opposite between the first and second windings 60 and 61 are separated, an insulation layer 91 is laminated on an outer peripheral surface of the metal thin film 70, and a metal plate 90 which has a thickness thicker than that of the metal thin film 70 is laminated on the outer peripheral surface of the insulation layer 91. The metal plate 90 is provided with a separation part 95 so as to be a non-communication in a peripheral direction in the metal thin film 70.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an on-vehicle electric compressor.

  As a configuration of a common mode choke coil used in an inverter device for driving an electric motor in an in-vehicle electric compressor, Patent Document 1 discloses that an induced current is generated in a conductor when a normal mode current flows by covering with the conductor. A choke coil that is converted into flowing heat energy and has a damping effect is disclosed.

WO2017 / 170817

  By the way, in order to increase the resistance component in the conductor and change it into heat, the plate-like conductor is thinned to a thin film shape. In this case, if the heat generated due to the thin film in the conductor is not quickly released, there is a problem that the solder fixed to the conductor is melted. There are also problems such as deterioration of the coating of the coil windings in the vicinity and changes in the magnetic characteristics of the cores in the vicinity.

  The objective of this invention is providing the vehicle-mounted electric compressor which has a filter circuit excellent in heat dissipation.

  According to the first aspect of the present invention, the apparatus includes a compression unit that compresses fluid, an electric motor that drives the compression unit, and an inverter device that drives the electric motor, and the inverter device converts DC power into AC power. An inverter circuit for converting to a noise reduction unit that is provided on the input side of the inverter circuit and reduces common mode noise and normal mode noise included in the DC power before being input to the inverter circuit, The noise reduction unit includes a common mode choke coil and a smoothing capacitor that forms a low-pass filter circuit together with the common mode choke coil, and the common mode choke coil is wound around the annular core and the core. The first winding is wound around the core and faces away from the first winding. A second winding, and an annular and thin-film conductor covering the core while straddling the first winding and the second winding, the conductor being the first winding And the second winding are separated from each other, an insulating layer is laminated on the outer peripheral surface of the conductor, and the outer peripheral surface of the insulating layer is thicker than the conductor The gist of the invention is that metal heat dissipation layers are laminated, and the heat dissipation layer is provided with slits that are discontinuous in the circumferential direction of the conductor.

  According to the first aspect of the present invention, the annular and thin film conductor covering the core while straddling the first winding and the second winding in the common mode choke coil is formed. Also, an insulating layer is laminated on the outer peripheral surface of the conductor, and a metal heat dissipation layer that is thicker than the conductor is laminated on the outer peripheral surface of the insulating layer. Therefore, the heat generated in the conductor is released through the metal plate for heat dissipation, and the heat dissipation is excellent. In addition, since the metal heat dissipation layer is provided with slits so as to be discontinuous in the circumferential direction of the conductor, the leakage magnetic flux generated even when the first winding and the second winding are energized. Inductive current does not flow in the circumferential direction inside the heat dissipation layer so as to generate magnetic flux in the direction of resistance.

  As described in claim 2, in the in-vehicle electric compressor according to claim 1, in the laminated body of the conductor, the insulating layer, and the heat dissipation layer, the conductor protrudes from other layers at both ends. In addition, it is preferable that only the protruding portion is joined to each other so that the conductor has an annular shape.

  As described in claim 3, in the in-vehicle electric compressor according to claim 1 or 2, it is preferable to further include a heat dissipating member thermally joined to the heat dissipating layer.

  ADVANTAGE OF THE INVENTION According to this invention, it can have a filter circuit excellent in heat dissipation.

The schematic diagram which shows the outline | summary of the vehicle-mounted electric compressor. The circuit diagram of a drive device and an electric motor. (A) is a plan view of a common mode choke coil, (b) is a front view of the common mode choke coil, (c) is a right side view of the common mode choke coil, and (d) is an AA line in (a). FIG. (A), (b) is the state figure which expand | deployed the strip | belt-shaped member. (A), (b) is the state figure which connected the both ends of the strip | belt-shaped member. (A) is a top view of a core and a coil | winding, (b) is a front view of a core and a coil | winding, (c) is a right view of a core and a coil | winding. The perspective view of the core and coil | winding for demonstrating an effect | action. The perspective view of the common mode choke coil for demonstrating an effect | action. The side view of a common mode choke coil. The graph which shows the frequency characteristic of the gain of a low-pass filter circuit. Sectional drawing of the common mode choke coil of another example.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. The on-vehicle electric compressor of this embodiment includes a compression unit that compresses a refrigerant as a fluid, and is used in an on-vehicle air conditioner. That is, the fluid to be compressed by the in-vehicle electric compressor in the present embodiment is a refrigerant.

  As shown in FIG. 1, the in-vehicle air conditioner 10 includes an in-vehicle electric compressor 11 and an external refrigerant circuit 12 that supplies a refrigerant as a fluid to the in-vehicle electric compressor 11. The external refrigerant circuit 12 has, for example, a heat exchanger and an expansion valve. The in-vehicle air conditioner 10 cools and heats the interior of the vehicle by compressing the refrigerant by the in-vehicle electric compressor 11 and performing heat exchange and expansion of the refrigerant by the external refrigerant circuit 12.

  The in-vehicle air conditioner 10 includes an air conditioning ECU 13 that controls the entire in-vehicle air conditioner 10. The air conditioning ECU 13 is configured to be able to grasp the in-vehicle temperature, the set temperature of the car air conditioner, and the like, and transmits various commands such as an ON / OFF command to the in-vehicle electric compressor 11 based on these parameters.

The vehicle-mounted electric compressor 11 includes a housing 14 in which a suction port 14 a through which refrigerant is sucked from an external refrigerant circuit 12 is formed.
The housing 14 is formed of a material having heat conductivity (for example, a metal such as aluminum). The housing 14 is grounded to the vehicle body.

  The housing 14 has a suction housing 15 and a discharge housing 16 assembled to each other. The suction housing 15 has a bottomed cylindrical shape that opens in one direction, and includes a plate-like bottom wall portion 15a and a side wall portion 15b that stands from the peripheral edge of the bottom wall portion 15a toward the discharge housing 16. Yes. The bottom wall portion 15a has a substantially plate shape, for example, and the side wall portion 15b has a substantially cylindrical shape, for example. The discharge housing 16 is assembled to the suction housing 15 in a state where the opening of the suction housing 15 is closed. Thereby, an internal space is formed in the housing 14.

  The suction port 14 a is formed in the side wall portion 15 b of the suction housing 15. Specifically, the suction port 14 a is disposed on the bottom wall portion 15 a side of the side wall portion 15 b of the suction housing 15 with respect to the discharge housing 16.

  The housing 14 has a discharge port 14b through which a refrigerant is discharged. The discharge port 14 b is formed in a portion facing the discharge housing 16, specifically, the bottom wall portion 15 a in the discharge housing 16.

The vehicle-mounted electric compressor 11 includes a rotating shaft 17, a compression unit 18, and an electric motor 19 that are accommodated in a housing 14.
The rotating shaft 17 is supported so as to be rotatable with respect to the housing 14. The rotating shaft 17 is arranged in a state where the axial direction thereof coincides with the thickness direction of the plate-like bottom wall portion 15a (in other words, the axial direction of the cylindrical side wall portion 15b). The rotating shaft 17 and the compression part 18 are connected.

  The compression portion 18 is disposed closer to the discharge port 14 b than the suction port 14 a (in other words, the bottom wall portion 15 a) in the housing 14. The compressor 18 compresses the refrigerant sucked into the housing 14 from the suction port 14a by rotating the rotating shaft 17, and discharges the compressed refrigerant from the discharge port 14b. In addition, the specific structure of the compression part 18 is arbitrary, such as a scroll type, a piston type, and a vane type.

  The electric motor 19 is disposed between the compression portion 18 and the bottom wall portion 15 a in the housing 14. The electric motor 19 drives the compression unit 18 by rotating the rotating shaft 17 in the housing 14. The electric motor 19 includes, for example, a cylindrical rotor 20 fixed to the rotating shaft 17 and a stator 21 fixed to the housing 14. The stator 21 has a cylindrical stator core 22 and a coil 23 wound around teeth formed on the stator core 22. The rotor 20 and the stator 21 face each other in the radial direction of the rotating shaft 17. When the coil 23 is energized, the rotor 20 and the rotating shaft 17 rotate, and the refrigerant is compressed by the compression unit 18.

  As shown in FIG. 1, the in-vehicle electric compressor 11 drives an electric motor 19 and is provided with a driving device 24 to which DC power is input and a cover member that defines a storage chamber S0 that houses the driving device 24. 25.

The cover member 25 is made of a nonmagnetic conductive material (for example, a metal such as aluminum) having heat conductivity.
The cover member 25 has a bottomed cylindrical shape that opens toward the housing 14, specifically, the bottom wall portion 15 a of the suction housing 15. The cover member 25 is attached to the bottom wall portion 15a of the housing 14 with a bolt 26 in a state where the open end is abutted against the bottom wall portion 15a. The opening of the cover member 25 is closed by the bottom wall portion 15a. The storage chamber S0 is formed by the cover member 25 and the bottom wall portion 15a.

  The storage chamber S0 is disposed outside the housing 14, and is disposed on the side opposite to the electric motor 19 with respect to the bottom wall portion 15a. The compression unit 18, the electric motor 19, and the driving device 24 are arranged in the axial direction of the rotary shaft 17.

  The cover member 25 is provided with a connector 27, and the driving device 24 is electrically connected to the connector 27. Direct current power is input to the drive device 24 from the in-vehicle power storage device 28 mounted on the vehicle via the connector 27, and the air conditioning ECU 13 and the drive device 24 are electrically connected. The in-vehicle power storage device 28 is a direct current power source mounted on the vehicle, such as a secondary battery or a capacitor.

  As shown in FIG. 1, the driving device 24 includes a circuit board 29, an inverter device 30 provided on the circuit board 29, and two connections used to electrically connect the connector 27 and the inverter device 30. Lines EL1 and EL2 are provided.

The circuit board 29 is plate-shaped. The circuit board 29 is disposed so as to face the bottom wall portion 15a with a predetermined interval in the axial direction of the rotary shaft 17.
The inverter device 30 is for driving the electric motor 19. The inverter device 30 includes an inverter circuit 31 (see FIG. 2) and a noise reduction unit 32 (see FIG. 2). The inverter circuit 31 is for converting DC power into AC power. The noise reduction unit 32 is provided on the input side of the inverter circuit 31 and serves to reduce common mode noise and normal mode noise included in DC power before being input to the inverter circuit 31.

Next, the electrical configuration of the electric motor 19 and the driving device 24 will be described.
As shown in FIG. 2, the coil 23 of the electric motor 19 has a three-phase structure including, for example, a u-phase coil 23u, a v-phase coil 23v, and a w-phase coil 23w. Each coil 23u-23w is Y-connected, for example.

  The inverter circuit 31 includes u-phase switching elements Qu1, Qu2 corresponding to the u-phase coil 23u, v-phase switching elements Qv1, Qv2 corresponding to the v-phase coil 23v, and w-phase switching elements Qw1, corresponding to the w-phase coil 23w. Qw2. Each of the switching elements Qu1 to Qw2 is a power switching element such as an IGBT. The switching elements Qu1 to Qw2 include freewheeling diodes (body diodes) Du1 to Dw2.

  The u-phase switching elements Qu1 and Qu2 are connected to each other in series via a connection line, and the connection line is connected to the u-phase coil 23u. The series connection body of the u-phase switching elements Qu1 and Qu2 is electrically connected to both connection lines EL1 and EL2, and DC power from the in-vehicle power storage device 28 is input to the series connection body. ing.

  The other switching elements Qv1, Qv2, Qw1, and Qw2 have the same connection mode as the u-phase switching elements Qu1 and Qu2, except that the corresponding coils are different.

  The driving device 24 includes a control unit 33 that controls the switching operation of the switching elements Qu1 to Qw2. The control unit 33 can be realized by, for example, one or more dedicated hardware circuits and / or one or more processors (control circuits) that operate according to a computer program (software). The processor includes a CPU and memories such as a RAM and a ROM, and the memory stores program codes or instructions configured to cause the processor to execute various processes, for example. Memory or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer.

  The control unit 33 is electrically connected to the air conditioning ECU 13 via the connector 27, and periodically turns on / off each of the switching elements Qu1 to Qw2 based on a command from the air conditioning ECU 13. Specifically, the control unit 33 performs pulse width modulation control (PWM control) on each of the switching elements Qu <b> 1 to Qw <b> 2 based on a command from the air conditioning ECU 13. More specifically, the control unit 33 generates a control signal using a carrier signal (carrier wave signal) and a command voltage value signal (comparison target signal). And the control part 33 converts direct-current power into alternating current power by performing ON / OFF control of each switching element Qu1-Qw2 using the produced | generated control signal.

  The noise reduction unit 32 includes a common mode choke coil 34 and an X capacitor 35. The X capacitor 35 as a smoothing capacitor constitutes a low-pass filter circuit 36 together with the common mode choke coil 34. The low-pass filter circuit 36 is provided on the connection lines EL1 and EL2. The low-pass filter circuit 36 is provided between the connector 27 and the inverter circuit 31 in terms of circuit.

The common mode choke coil 34 is provided on both connection lines EL1, EL2.
The X capacitor 35 is provided in the subsequent stage (inverter circuit 31 side) with respect to the common mode choke coil 34, and is electrically connected to both connection lines EL1 and EL2. The common mode choke coil 34 and the X capacitor 35 constitute an LC resonance circuit. That is, the low-pass filter circuit 36 of the present embodiment is an LC resonance circuit including the common mode choke coil 34.

  Both Y capacitors 37 and 38 are connected in series with each other. Specifically, the driving device 24 includes a bypass line EL <b> 3 that connects one end of the first Y capacitor 37 and one end of the second Y capacitor 38. The bypass line EL3 is grounded to the vehicle body.

  Further, a series connection body of both Y capacitors 37 and 38 is provided between the common mode choke coil 34 and the X capacitor 35, and is electrically connected to the common mode choke coil 34. The other end of the first Y capacitor 37 opposite to the one end is connected to the first connection line EL1, more specifically, the first winding of the common mode choke coil 34 in the first connection line EL1 and the inverter circuit 31. It is connected to the part. The other end of the second Y capacitor 38 opposite to the one end is connected to the second connection line EL2, more specifically, the second winding of the common mode choke coil 34 in the second connection line EL2 and the inverter circuit 31. It is connected to the part.

  In the vehicle, for example, a PCU (power control unit) 39 is mounted as a vehicle-mounted device separately from the driving device 24. The PCU 39 uses a DC power supplied from the in-vehicle power storage device 28 to drive a traveling motor or the like mounted on the vehicle. That is, in the present embodiment, the PCU 39 and the drive device 24 are connected in parallel to the in-vehicle power storage device 28, and the in-vehicle power storage device 28 is shared by the PCU 39 and the drive device 24.

  The PCU 39 includes, for example, a boost converter 40 that has a boost switching element and boosts DC power of the in-vehicle power storage device 28 by periodically turning the boost switching element ON / OFF in parallel with the in-vehicle power storage device 28. And a power supply capacitor 41 connected thereto. Although not shown, the PCU 39 includes a traveling inverter that converts the DC power boosted by the boost converter 40 into driving power that can be driven by the traveling motor.

  In such a configuration, noise generated due to switching of the step-up switching element flows into the driving device 24 as normal mode noise. In other words, the normal mode noise includes a noise component corresponding to the switching frequency of the step-up switching element.

  Next, the configuration of the common mode choke coil 34 is shown in FIGS. 3 (a), (b), (c), (d), FIGS. 4 (a), (b), FIGS. 5 (a), (b), and FIG. 6 (a), (b), and (c) will be used for explanation.

  The common mode choke coil 34 is for suppressing high-frequency noise generated in the PCU 39 on the vehicle side from being transmitted to the inverter circuit 31 on the compressor side. Used as an L component in a low-pass filter circuit (LC filter) 36 for removing noise (differential mode noise). In other words, it can cope with common mode noise and normal mode noise (differential mode noise). Both the common mode choke coil and the normal mode (differential mode) choke coil are not used, but both are used with one choke coil. It can cope with mode noise.

In the drawing, three-axis orthogonal coordinates are defined, the axial direction of the rotating shaft 17 in FIG. 1 is the Z direction, and the directions orthogonal to the Z direction are the X and Y directions.
As shown in FIGS. 3A, 3 </ b> B, 3 </ b> C, and 3 </ b> D, the common mode choke coil 34 includes an annular core 50, a first winding 60, and a second winding 61. And a metal thin film 70 as a conductor.

  The core 50 has a quadrangular cross section as shown in FIG. 3 (d), and has a rectangular shape as a whole in the XY plane shown in FIG. 6 (a). As shown in FIGS. 3D and 6A, the core 50 has an inner space Sp1.

  As shown in FIGS. 6A, 6 </ b> B, and 6 </ b> C, the first winding 60 is wound around the core 50, and the second winding 61 is wound around the core 50. . More specifically, as shown in FIG. 6A, one long side portion of the rectangular core 50 forms the first straight portion 51, and the other long side portion forms the second straight portion 52. The first straight line portion 51 and the second straight line portion 52 are parallel to each other. At least a part of the first winding 60 is wound around the first straight part 51, and at least a part of the second winding 61 is wound around the second straight part 52. The winding directions of both windings 60 and 61 are opposite to each other. Further, the first winding 60 and the second winding 61 are opposed to each other while being separated from each other.

A resin case (not shown) is provided between the core 50 and the windings 60 and 61, and a projection (not shown) extends from the resin case to regulate the metal thin film 70.
As shown in FIGS. 3A, 3B, 3C, and 3D, the metal thin film 70 is made of a copper foil. The thickness of the metal thin film 70 is 10 μm to 100 μm. For example, the thickness of the metal thin film 70 is 35 μm. The reason for reducing the thickness is to increase the resistance to heat when an electric current (inductive current) flows. On the other hand, when it is thin, it is difficult to maintain strength and shape.

  As shown in FIGS. 3C and 3D, the metal thin film 70 is annular, and specifically has a strip shape and an endless shape. The metal thin film 70 covers the core 50 while straddling the first winding 60 and the second winding 61, and more specifically, all of the first winding 60 and all of the second winding 61. It is formed so as to cover a part of the inner space Sp1 of the core 50 (see FIG. 3D and FIG. 6A). In a broad sense, the metal thin film 70 covers at least part of each of the first winding 60, the second winding 61, and the inner space Sp1 of the core 50 (see FIGS. 3D and 6A). It is formed as follows. It can be said that the inner space Sp1 is between the first winding 60 and the second winding 61, and the metal thin film 70 is located between the first winding 60 and the second winding 61, that is, the inner space. The parts facing each other across Sp1 are separated from each other.

The metal thin film 70 has a resin layer 80 formed between the inner peripheral surface of the thin film and the outer surfaces of the first winding 60 and the second winding 61.
As described above, the insulating layer 91 is laminated on the outer peripheral surface of the metal thin film 70, and the metal plate 90 as a metal heat dissipation layer thicker than the metal thin film 70 is laminated on the outer peripheral surface of the insulating layer 91. Yes.

  As shown in FIGS. 3C and 3D, the resin layer 80 ensures the insulation of the metal thin film 70 while maintaining the strength and high rigidity. The resin layer 80 is made of polyimide, and can maintain strength with respect to the thin metal thin film 70. The thickness of the resin layer 80 is, for example, several tens of μm. This is because it is desirable that the windings 60 and 61 and the metal thin film 70 are closer to each other, and an induced current flows by receiving the magnetic field generated by the windings 60 and 61 by the metal thin film 70. Inductive current flows easily.

  The metal thin film 70 and the resin layer 80 are bonded by an adhesive (not shown). The adhesive may be a thermosetting adhesive (adhesive), a thermoplastic type adhesive (hot melt), or a pressure sensitive adhesive (pressure-sensitive adhesive).

  The common mode choke coil 34 includes a metal plate 90 as a heat dissipation layer. The metal plate 90 is made of copper foil. The metal plate 90 is disposed on the outer peripheral surface of the metal thin film 70 along the circumferential direction of the metal thin film 70 via the insulating layer 91 and in a discontinuous state in the circumferential direction. The thickness of the metal plate 90 for heat dissipation is larger than the thickness of the metal thin film 70. For example, if the thickness of the metal thin film 70 is 35 μm, the thickness of the metal plate 90 for heat dissipation is about 70 μm. The heat dissipating metal plate 90 makes it easy to dissipate heat transmitted through the insulating layer 91.

  The insulating layer 91 is a heat conductive adhesive layer, and reduces the heat resistance between the metal thin film 70 and the heat radiating metal plate 90 to effectively transfer the heat generated in the metal thin film 70 to the heat radiating metal plate 90. I can tell you. The insulating layer 91 is excellent in insulation and thermal conductivity. The heat dissipating metal plate 90 has a slit 95 that is slit-like in the circumferential direction, and is thus discontinuous in the circumferential direction. As a result, an induced current flows through the metal thin film 70 in the circumferential direction, but an induced current does not flow through the metal plate 90 for heat dissipation.

  More specifically, as shown in FIGS. 4A and 4B, in the laminate of the metal plate 90, the insulating layer 91, the metal thin film 70, and the resin layer 80, the metal thin film 70 protrudes from other layers at both ends. As shown in FIGS. 5 (a) and 5 (b), only the protruding portions are joined to each other by welding or the like, so that the metal thin film 70 forms a ring shape. In a broad sense, the laminated body of the metal thin film 70, the insulating layer 91, and the metal plate 90 has the metal thin film 70 protruding from the other layers on both sides, and the metal thin film 70 is strip-like and endless by joining only the protruding portions. Shape. As a result, an induced current flows in the metal thin film 70. Moreover, since the metal plate 90 is not joined, it becomes discontinuous in the circumferential direction.

  The bottom wall 15a in FIG. 1 serves as a heat dissipation member for the common mode choke coil 34, and the metal plate 90 is thermally joined to the bottom wall 15a as shown in FIGS. 3 (b) to 3 (d). . That is, the heat generated in the common mode choke coil 34 is released to the bottom wall portion 15a. At this time, the part of the separation part 95 of the metal plate 90 for heat dissipation is not brought into contact with the bottom wall part 15a. This is to prevent induced current from flowing in the circumferential direction through the bottom wall 15a made of aluminum in the metal plate 90 for heat dissipation.

Next, the operation will be described.
First, the normal mode (differential mode) will be described with reference to FIGS.

  As shown in FIG. 7, currents i <b> 1 and i <b> 2 flow by energization of the first winding 60 and the second winding 61. Accordingly, magnetic fluxes φ1 and φ2 are generated in the core 50, and leakage magnetic fluxes φ3 and φ4 are generated. Magnetic fluxes φ1 and φ2 are opposite to each other, and leakage magnetic fluxes φ3 and φ4 are generated. Here, as shown in FIG. 8, an induced current i10 flows in the circumferential direction inside the metal thin film 70 so as to generate a magnetic flux in a direction against the generated leakage magnetic fluxes φ3 and φ4.

  In this way, in the metal thin film 70, an induced current (eddy current) i10 is generated inside so as to generate a magnetic flux in a direction against the leakage magnetic flux generated by energization of the first winding 60 and the second winding 61. Flows in the circumferential direction. The induced current flowing in the circumferential direction means flowing around the core 50.

  In the common mode, current flows in the same direction by energization of the first winding 60 and the second winding 61. As a result, a magnetic flux in the same direction is generated in the core 50. In this way, when the common mode current is energized, a magnetic flux is generated inside the core 50 and almost no leakage magnetic flux is generated, so that the common impedance can be maintained.

  Next, frequency characteristics of the low-pass filter circuit 36 will be described with reference to FIG. FIG. 10 is a graph showing the frequency characteristics of the gain (attenuation) of the low-pass filter circuit 36 with respect to the normal mode noise that flows. The solid line in FIG. 10 shows the case where the common mode choke coil 34 has a thin film 70 made of a conductor, and the alternate long and short dash line in FIG. 10 shows the case where the common mode choke coil 34 has no thin film 70 made of a conductor. Further, in FIG. 10, the frequency on the horizontal axis is indicated by a logarithm. The gain is a kind of parameter indicating the amount by which normal mode noise can be reduced.

  As shown by the one-dot chain line in FIG. 10, when the thin film 70 made of a conductor is not present in the common mode choke coil 34, the low pass filter circuit 36 (specifically, the LC including the common mode choke coil 34 and the X capacitor 35). The Q value of the (resonance circuit) is relatively high. For this reason, normal mode noise having a frequency close to the resonance frequency of the low-pass filter circuit 36 is difficult to reduce.

  On the other hand, in the present embodiment, a thin film 70 made of a conductor is provided at a position where an eddy current is generated by a magnetic field line (leakage magnetic flux φ3, φ4) generated in the common mode choke coil 34. The thin film 70 made of a conductor is provided at a position through which the leakage fluxes φ3 and φ4 penetrate, and an induced current (vortex) that generates a magnetic flux in a direction that cancels the leakage fluxes φ3 and φ4 when the leakage fluxes φ3 and φ4 penetrate. Current). As a result, the thin film 70 made of a conductor functions to lower the Q value of the low-pass filter circuit 36. Therefore, as indicated by the solid line in FIG. 10, the Q value of the low-pass filter circuit 36 is low. Therefore, normal mode noise having a frequency near the resonance frequency of the low-pass filter circuit 36 is also reduced by the low-pass filter circuit 36.

  As described above, the common mode choke coil employs a metal shield structure formed of a band-like and endless metal thin film 70, so that the common mode choke coil is used in a low-pass filter circuit to reduce common mode noise. In addition, it is possible to obtain appropriate filter characteristics that can reduce normal mode noise (differential mode noise) by actively utilizing leakage magnetic flux generated with respect to normal mode current (differential mode current). That is, by using the strip-shaped and endless metal thin film 70, a magnetic flux is generated against the leakage magnetic flux generated when the normal mode current (differential mode current) is energized, and the current flows through the metal thin film 70 by electromagnetic induction and is consumed as heat. Is done. Since the metal thin film 70 functions as a magnetic resistance, a damping effect can be obtained and a resonance peak generated by the low-pass filter circuit can be suppressed (see FIG. 10). Further, when the common mode current is applied, a magnetic flux is generated inside the core and a leakage magnetic flux is hardly generated, so that the common impedance can be maintained. Furthermore, by having a resin layer (polyimide layer) 80 on the inner peripheral side of the metal thin film (metal foil) 70, the shape can be maintained and insulation from the windings 60 and 61 can be secured.

  In this way, the metal thin film 70 having a strip shape and an endless shape is installed in the direction in which the magnetic flux resisting the leakage magnetic flux is generated, and an electric current flows to consume the electric power in an attempt to generate the magnetic flux in the direction resisting the leakage magnetic flux. Fever. At this time, the heat resistance of the resin layer 80, the coating on the windings 60 and 61, and the core 50 becomes a problem.

As shown in FIG. 9, the heat Q generated in the common mode choke coil 34 is released to the bottom wall portion 15a because the metal plate 90 for heat dissipation is thermally joined to the bottom wall portion 15a.
According to the above embodiment, the following effects can be obtained.

  (1) As a configuration of the on-vehicle electric compressor 11, an inverter device 30 that drives the electric motor 19 is provided. The inverter device 30 includes an inverter circuit 31 and a noise reduction unit 32, and the noise reduction unit 32 includes an X capacitor 35 as a smoothing capacitor that constitutes a low-pass filter circuit 36 together with the common mode choke coil 34 and the common mode choke coil 34. And comprising. The common mode choke coil 34 includes an annular core 50, a first winding 60 wound around the core 50, and a second winding wound around the core 50 and facing away from the first winding 60. A winding 61 and a metal thin film 70 as an annular and thin film conductor covering the core 50 while straddling the first winding 60 and the second winding 61 are provided. In the metal thin film 70, the opposing portions are separated from each other between the first winding 60 and the second winding 61, and an insulating layer 91 is laminated on the outer peripheral surface of the metal thin film 70, and the outer periphery of the insulating layer 91 is On the surface, a metal plate 90 is laminated as a metal heat dissipation layer which is thicker than the metal thin film 70. The metal plate 90 is provided with a separation portion 95 as a slit so as to be discontinuous in the circumferential direction of the metal thin film 70.

  Therefore, the heat generated in the metal thin film 70 is released through the metal plate 90 for heat dissipation, and the heat dissipation is excellent. Further, since the metal metal plate 90 is provided with a separation portion 95 as a slit so as to be discontinuous in the circumferential direction in the metal thin film 70, the first winding 60 and the second winding 61 are provided in the metal winding 90. Even when energized, the induced current does not flow in the circumferential direction inside the metal plate 90 so as to generate magnetic flux in a direction against the generated leakage magnetic flux. In addition, the heat-dissipating metal plate 90 thicker than the metal thin film 70 becomes a heat mass, and the heat dissipation is good.

  (2) In the laminate of the metal thin film 70, the insulating layer 91, and the metal plate 90, the metal thin film 70 protrudes from the other layers at both ends, and the metal thin film 70 forms a ring shape by joining only the protruding portions. Therefore, the annular metal thin film 70 can be easily manufactured.

  (3) It further includes a bottom wall portion 15a as a heat radiating member that is thermally joined to the metal plate 90. Therefore, it is further excellent in heat dissipation. That is, cooling by the refrigerant can be expected by thermally coupling the heat radiating metal plate 90 to the aluminum member that is the bottom wall portion 15a.

The embodiment is not limited to the above, and may be embodied as follows, for example.
As shown in FIG. 11, the laminate of the resin layer 80, the metal thin film 70, the insulating layer 91, and the metal plate 90 has the resin layer 80 as the innermost layer, and the end portions 70 a and 70 b of the metal thin film 70 on the outer peripheral side The end portions 90a and 90b of the metal plate 90 are arranged on the outer peripheral side through the insulating layer 91 so that the metal thin film 70 has a strip shape and an endless shape, and the metal plate 90 is arranged in a discontinuous state. Also good.

The resin layer 80 may be made of polyester, PET, PEN or the like in addition to polyimide.
The windings 60 and 61 and the metal thin film (thin film made of a conductor) 70 may be held separately (individually).

  The metal thin film 70 may be made of aluminum foil, brass foil, stainless steel foil, or the like in addition to the copper foil. Moreover, not only nonmagnetic metals, such as copper, but a magnetic metal may be used. Here, when a magnetic metal such as iron is used, the metal thin film 70 is preferably a non-magnetic metal because a magnetic flux is further generated as an induced current flows, which may have an adverse effect.

The metal thin film 70 may be formed so as to cover the entire length of the core 50 (the total length in the X direction in FIG. 3A).
The metal plate 90 for heat dissipation may be aluminum, stainless steel, etc. instead of copper.

As shown in FIG. 3C and the like, the heat-dissipating metal plate 90 has the separation portion 95 only at one place in the circumferential direction, but may have the separation portions at a plurality of places in the circumferential direction.
O Although heat was released from the heat radiating metal plate 90 to the bottom wall portion 15a as a heat radiating member, heat may be released from the heat radiating metal plate 90 to the atmosphere.

  DESCRIPTION OF SYMBOLS 11 ... Electric compressor for vehicles, 18 ... Compression part, 19 ... Electric motor, 30 ... Inverter device, 31 ... Inverter circuit, 32 ... Noise reduction part, 34 ... Common mode choke coil, 35 ... X capacitor, 36 ... Low pass filter Circuit: 50 ... Core, 51 ... First straight part, 52 ... Second straight part, 60 ... First winding, 61 ... Second winding, 70 ... Metal thin film, 90 ... Metal plate, 91 ... Insulation layer.

Claims (3)

A compression section for compressing the fluid;
An electric motor for driving the compression unit;
An inverter device for driving the electric motor,
The inverter device is
An inverter circuit for converting DC power into AC power;
A noise reduction unit that is provided on the input side of the inverter circuit and reduces common mode noise and normal mode noise included in the DC power before being input to the inverter circuit,
The noise reduction unit is
A common mode choke coil;
A smoothing capacitor that constitutes a low-pass filter circuit together with the common mode choke coil,
The common mode choke coil is
An annular core,
A first winding wound around the core;
A second winding wound around the core and facing away from the first winding;
An annular and thin film conductor covering the core while straddling the first winding and the second winding,
The conductors are spaced apart from each other between the first winding and the second winding,
An insulating layer is laminated on the outer peripheral surface of the conductor, and a metal heat dissipation layer that is thicker than the conductor is laminated on the outer peripheral surface of the insulating layer,
The in-vehicle electric compressor, wherein the heat dissipation layer is provided with slits so as to be discontinuous in the circumferential direction of the conductor.   The laminate of the conductor, the insulating layer, and the heat dissipation layer is characterized in that the conductor protrudes from other layers at both ends, and the conductor forms an annular shape by bonding only the protruding portions to each other. The in-vehicle electric compressor according to claim 1.   The in-vehicle electric compressor according to claim 1, further comprising a heat dissipating member thermally bonded to the heat dissipating layer.