Electric compressor

An electric compressor includes a compression mechanism, an electric motor for driving the compression mechanism, and a drive circuit for controlling the electric motor. The drive circuit includes an external connector made of an insulating material. The external connector has a connecting terminal that is constructed to be electrically connected to an external power source. The drive circuit further includes a circuit board electrically connected to the connecting terminal and a filter element electrically connected to the circuit board. The drive circuit is accommodated in a metal housing. The filter element is integrally formed with the external connector such that contact of the filter element with the housing is prevented.

ART OF THE DISCLOSURE

The present disclosure relates to an electric compressor. An electric compressor includes a compression mechanism, an electric motor for driving the compression mechanism, and a drive circuit for controlling the electric motor.

BACKGROUND

The drive circuit of this type of electric compressor is accommodated in a metal housing. The drive circuit has an external connector to be electrically connected to a vehicle battery, which is an external power source. Electrical components on the circuit board receive electric power via the external connector. An inverter circuit for driving the electric motor and a switching element for performing switching control of the inverter circuit are mounted on the circuit board. Also, a filter coil and filter capacitors are mounted on the circuit board. The filter coil and the filter capacitors are filter elements, which protect switching elements from instantaneous and excessive currents and reduce noise.

As described above, a great number of electric circuits and electrical components are mounted on the circuit board of a drive circuit. Since the sizes of filter coils and filter capacitors are large, the circuit board has adhesive applied thereon to reduce vibration and parts having auxiliary functions for fixing the board with bolts. As a result, circuit boards tend to be large.

Accordingly, to reduce the size of circuit boards, for example, Japanese Laid-Open Patent Publication No. 2007-309125 discloses an on-vehicle electric circuit unit mounted on an electric compressor. A circuit board and electric elements are accommodated in a housing formed by an upper case and a lower case. A power inputting terminal is fixed to the upper case. The power inputting terminal is an external connector that is electrically connected to an external power source. The power inputting terminal is also connected to a filter coil, filter capacitors, and an inverter control board, which is a circuit board, via a busbar.

The filter coil of an on-vehicle electric circuit unit is fixed to the upper surface of the upper case with fixing members. The filter capacitors are fixed to a side of the upper case with other fixing members. Therefore, compared to, for example, a case where a filter coil and filter capacitors are mounted on one component side of an inverter control board, the size of the component side is reduced. That is, the size of the inverter control board is reduced.

However, according to the electric compressor disclosed in the document, the filter coil and the filter capacitors are fixed to the upper case, or to the housing, while being pressed against the inner wall of the upper case. Therefore, when the coatings of the filter capacitors and the filter coil are worn due to vibrations applied from the outside, the electrical insulation of the housing, which contacts the filter capacitors and the filter coil, is difficult to maintain.

SUMMARY

Accordingly, it is an objective of the present invention to reduce the size of a circuit board and maintain the insulation of circuit board components from a housing in an electric compressor.

An electric compressor disclosed herein includes a compression mechanism, an electric motor that drives the compression mechanism, and a drive circuit for controlling the electric motor. The drive circuit includes an external connector, a circuit board, and a filter element. The external connector is made of an insulating material, and has a connecting terminal constructed to be electrically connected to an external power source. The circuit board is electrically connected to the connecting terminal. The filter element is electrically connected to the circuit board. The drive circuit is accommodated in a metal housing. The filter element is integrally molded with the external connector such that contact of the filter element with the housing is prevented.

According to this configuration, the external connector prevents filter elements from contacting the metal housing. This ensures the electrical insulation of the filter elements from the housing. Also, the filter elements are integrally formed with the external connector. Thus, the size of the circuit board is reduced compared to a case where all the filter elements are mounted on the same component side of a circuit board.

In accordance with one aspect, the filter element comprises at least one of a coil and a capacitor.

According to this configuration, at least one of a coil and a capacitor is formed integrally with the external connector. A filter element is thus embedded in the external connector, and the external connector is interposed between the filter element and the housing. Accordingly, for example, vibrations applied from outside are prevented from damaging the filter element.

In accordance with one aspect, the electric compressor further includes a conducting member that extends through the housing and is electrically connected to the electric motor, and a board connector that is arranged in the housing and electrically connected to the circuit board. The conducting member is connected to the board connector, so that the electric motor is electrically connected to the circuit board. The board connector is integrated with the external connector.

According to this configuration, most of the members about the circuit board are permitted to be integrated. Accordingly, the drive circuit is easily installed in the housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1(a) and1(b) show a first embodiment. In these drawings, the axial direction of an electric compressor10, that is, the direction along which the axis L of a rotary shaft17of the electric compressor10extends, is the left-right direction.

As shown inFIG. 1(a), the electric compressor10includes a first housing11and a second housing12. The second housing12has a cylindrical shape with a closed end, and the first housing11closes the open end, or the left end as viewed inFIG. 1(a) of the second housing12. The first housing11also has a cylindrical shape with a closed end. The second housing12accommodates an electric motor16, which is arranged at a position close to a bottom wall12a, and a compression mechanism15, which is arranged at a position close to the first housing11. That is, the second housing12is a motor housing for accommodating the electric motor16. The interior of the second housing12is a motor accommodating space13for accommodating the electric motor16. In the present embodiment, the electric compressor10is a scroll compressor.

A stator18of the electric motor16is fixed to the inner circumferential surface of the second housing12. The stator18has a stator core18aand a motor coil18bwound about the stator core18a. The rotary shaft17is rotatably supported by the second housing12via bearings (not shown). A rotor19of the electric motor16is fixed to the rotary shaft17to rotate integrally with the rotary shaft17. When the electric motor16is driven to rotate the rotary shaft17, the compression mechanism15is activated to compress, for example, refrigerant of a vehicle air conditioner.

An inverter cover20having a box-like shape with a closed end is secured to the bottom wall12aon the right side of the second housing12inFIG. 1(a). The first housing11, the second housing12, and the inverter cover20are made of aluminum and form a housing H of the electric compressor10. The bottom wall12aand the inverter cover20define a circuit accommodating space21. The circuit accommodating space21accommodates an inverter unit22, which is a drive circuit for driving the electric motor16. That is, the bottom wall12afunctions as a partition wall that divides the motor accommodating space13, which accommodates the electric motor16, and the circuit accommodating space21, which accommodates the inverter unit22, from each other. The inverter cover20is a circuit cover that is secured to the second housing12to cover the bottom wall12a, which serves as a wall of the second housing12.

More specifically, as shown inFIGS. 1(a) and1(b), the bottom wall12aof the second housing12is slightly inward (leftward as viewed in the drawing) from the axial end of the circumferential wall of the second housing12. That is, the second housing12has a circumferential wall12cthat extends axially outward (rightward as viewed in the drawing) from the bottom wall12a. The open end of the circumferential wall12c(the right end as viewed in the drawing) is joined to the open end of the inverter cover20(the left end as viewed in the drawing). In this manner, the bottom wall12a, the circumferential wall12c, and the inverter cover20define the circuit accommodating space21. In the present embodiment, the compression mechanism15, the electric motor16, and the inverter unit22are arranged in the order along the axial direction of the rotary shaft17. The inverter cover20has a power input port20a, which exposes the circuit accommodating space21to the outside.

As shown inFIG. 1(b), a plate-like heat removing member23is joined to the bottom wall12ato extend along the bottom wall12a. The inverter unit22is attached to the heat removing member23. The heat removing member23is made of aluminum having a high thermal conductivity and thermally coupled to the bottom wall12a. A board support member24is fixed to the heat removing member23to support a circuit board25of the inverter unit22. That is, while being separated from the heat removing member23, the circuit board25is thermally coupled to the heat removing member23via the board support member24. The circuit board25is arranged to be perpendicular to the axial direction of the electric compressor10.

The circuit board25is electrically connected to filter elements, which are a filter coil27and filter capacitors28. The filter capacitors28contact the heat removing member23.

That is, the filter capacitors28are mounted on the circuit board25without contacting any of the bottom wall12a, the circumferential wall12c, and the inverter cover20. Thus, contact of the filter capacitors28with the housing H is prevented. Although omitted to simplify the description, the circuit board25is electrically connected to an inverter circuit (not shown), which is a drive control circuit for the electric motor16, and switching elements (not shown).

The circuit board25is electrically connected to the motor coil18bby a sealed terminal30, which extends through the bottom wall12aof the second housing12. The sealed terminal30is located above the circuit board25as viewed in the drawing. The sealed terminal30is fixed to extend through an insulating member34formed on the bottom wall12a. The sealed terminal30has a motor connector31, which is electrically connected to the motor coil18bvia a lead31a, a board connector32, which is electrically connected to the circuit board25via a connecting member35, and a conducting member33, which connects the motor connector31to the board connector32. The conducting member33extends through the insulating member34. That is, the insulating member34fixes the conducting member33to the bottom wall12a, while insulating the conducting member33from the bottom wall12a. In this manner, the conducting member33extends through the bottom wall12a, which forms a part of the housing H.

The circuit board25has an external connector40to be electrically connected to a vehicle battery, which is an external power source. The external connector40is made of a resin material, that is, an insulating material, and has an external connecting terminal41to be electrically connected to the outside. The external connecting terminal41is located inside the power input port20a. That is, the outer shell of the external connector40is formed of a resin material. The external connecting terminal41is arranged in the power input port20ato face the outside of the circuit accommodating space21. The external connector40is electrically connected to a power inputting portion of the circuit board25via a connecting member43. The external connector40has a terminal holding portion44, which extends along the bottom wall12afrom the external connecting terminal41to the connecting member43, and the terminal holding portion44contacts the inverter cover20. Since they are supported and held between the bottom wall12aand the inverter cover20, the inverter unit22and the external connector40resist vibration.

The filter coil27is embedded in resin in the external connector40. The external connector40has a resin coil holding portion42, which is located on a side of the external connecting terminal41and relatively close to the circuit accommodating space21, and the coil holding portion42holds the filter coil27therein.

The external connector40of the present embodiment is a molded resin product that is integrated with the filter coil27through molding. A method for manufacturing the external connector40is as follows. With the filter coil27placed in a mold (not shown) for manufacturing the external connector40, molten resin is poured into the mold and then hardened. As a result, the filter coil27is embedded in the coil holding portion42.

The filter coil27is electrically connected to the circuit board25and the external connecting terminal41via a busbar incorporated in the terminal holding portion44.

Operation of the inverter unit22will now be described.

Electric power is supplied from a vehicle battery to the inverter unit22via the external connecting terminal41. Then, the drive control circuit controls the operation of the electric motor16to drive the compression mechanism15. During such supply of electric power, the filter coil27and the filter capacitors28protect the switching elements from instantaneous and excessive currents and reduce extrinsic noise.

As described above, the filter coil27is embedded in the resin external connector40. The filter capacitors28are mounted on the circuit board25while in contact with the heat removing member23. In this manner, the filter coil27and the filter capacitors28are insulated from the housing H of the electric compressor10.

The above described first embodiment has the following advantages.

(1) In the electric compressor10, the filter capacitors28, which are filter elements, are mounted on the circuit board25and are not in contact with the housing H. The housing H is formed by the bottom wall12a, the circumferential wall12c, and the inverter cover20. The filter coil27, which is another filter element, is integrated with the external connector40through molding. That is, the external connector40is molded integrally with the filter coil27with resin so that the filter coil27is embedded in the external connector40. Therefore, contact of the filter coil27with the housing H (the bottom wall12a, the circumferential wall12c, and the inverter cover20) is prevented. Therefore, in the electric compressor10, the electrical insulation between the housing H and the filter elements (the filter coil27and the filter capacitors28) is ensured. Only the filter capacitors28are mounted on the component side of the circuit board25. This reduces the size of the circuit board25compared to a case where both of the filter capacitors28and the filter coil27are mounted on the same component side of the circuit board25.

(2) The filter coil27is integrated with the external connector40through molding. The filter coil27is electrically connected to the circuit board25via the connecting member43of the external connector40. The filter capacitors28are soldered to the circuit board25. Therefore, the number of soldering spots has been reduced in the present embodiment compared to a case where the filter coil27and the filter capacitors28are both soldered to the circuit board25.

(3) The filter coil27, which is a filter element, is integrated with the external connector40through molding, to be held by the external connector40. That is, the resin part of the external connector40is located between the filter coil27and the inverter cover20. Accordingly, for example, vibrations applied from outside are prevented from damaging the filter coil27. In this manner, the external connector40reduces vibration of the filter coil27. Since the filter coil27does not need to be attached to the circuit board25with adhesive or a bolt designed for reducing vibration, the size of the circuit board25has been reduced.

(4) Of the filter coil27and the filter capacitors28, which are filter elements, the filter capacitors28are supported by being held in contact with the heat removing member23while being mounted on the circuit board25. The filter coil27is embedded in the external connector40. Therefore, the positions of the filter coil27and the filter capacitors28are determined without using any fixing members. Therefore, compared to a case where the positions of a filter coil and filter capacitors are both determined by fixing members, the number of components of the inverter unit22in the electric compressor10has been reduced.

(5) The inverter unit22is used to control the operation of the electric motor16of the electric compressor10. The filter coil27is a relatively heavy electrical component. Therefore, the filter coil27is likely to vibrate when the compression mechanism15or the electric motor16operates. In the present embodiment, the filter coil27is integrated with the external connector40through molding, which reduces vibration of the filter coil27.

FIG. 2shows a second embodiment. The second embodiment is different from the first embodiment in that both of the filter coil27and the filter capacitors28are integrated with an external connector50through molding. Like or the same reference numerals are given to those components that are like or the same as the corresponding components of the first embodiment.

Like the external connector40of the first embodiment, the external connector50of the second embodiment includes an external connecting terminal51, a coil holding portion52, and a terminal holding portion54, which are formed integrally, a shown inFIG. 2. Further, a capacitor holding portion55for holding the filter capacitors28is integrally formed with the external connector50. The coil holding portion52, the terminal holding portion54, and the capacitor holding portion55extend along the bottom wall12aof the second housing12. A connecting member53, which is integrated with the terminal holding portion54, is electrically connected with the circuit board25. The filter coil27and the filter capacitors28are electrically connected to the circuit board25and the external connecting terminal41via a busbar incorporated in the terminal holding portion54.

The second embodiment thus has the following advantages.

(6) The filter coil27and the filter capacitors28, which are filter elements, are integrated with the resin external connector50through molding. The filter coil27and the filter capacitors28do not contact the housing H. That is, contact of the filter coil27and the filter capacitors28with any of the bottom wall12a, the circumferential wall12c, and the inverter cover20is prevented. Therefore, the electrical insulation between the housing H and the filter elements (the coil27and the filter capacitors28) is ensured. In this embodiment, neither the filter coil27nor the filter capacitors28is mounted on the component side of the circuit board25. Thus, the circuit board25of the present embodiment has been reduced in size compared to a case where at least either of the filter capacitors28and the filter coil27is mounted on the same component side of the circuit board25.

(7) The filter coil27and the filter capacitors28are both integrated with the external connector50through molding. The filter coil27and the filter capacitors28are electrically connected to the circuit board25via the connecting member53of the external connector50. Therefore, the number of soldering spots has been reduced in the present embodiment compared to a case where at least either of the filter coil27and the filter capacitors28are soldered to the circuit board25.

(8) The filter coil27and the filter capacitors28, which are filter elements, are both integrated with the external connector50through molding. That is, the resin part of the external connector40is located between the filter coil27and the inverter cover20and between the filter capacitors28and the inverter cover20. Accordingly, for example, vibrations applied from outside are prevented from damaging the filter coil27and the filter capacitors28. That is, there is no need for the filter coil27or the filter capacitors28to be attached to the circuit board25with adhesive or bolts designed for reducing vibration. Therefore, the size of the circuit board25has reduced.

(9) The filter coil27and the filter capacitors28, which are filter elements, are both integrated with the external connector50through molding. That is, the positions of the filter coil27and the filter capacitors28are determined without using any fixing members. Therefore, compared to a case where the position of the filter coil27or the positions of the filter capacitors28are determined by using fixing members, the number of components of the inverter unit22in the electric compressor10is reduced.

(10) The inverter unit22is used to control the operation of the electric motor16of the electric compressor10. The filter coil27and the filter capacitors28are relatively heavy electrical components. Therefore, the filter coil27and the filter capacitors28are likely to vibrate when the compression mechanism15or the electric motor16operates. In the present embodiment, the filter coil27and the filter capacitors28are both incorporated in the external connector50. Therefore, vibration of both the filter coil27and the filter capacitors28is reduced.

FIG. 3shows a third embodiment. A capacitor holding portion65of the third embodiment is integrally formed with the board connector32of the sealed terminal30. That is, the external connector60of third embodiment is different from the second embodiment in that the sealed terminal30is integrated with the external connector60. Like or the same reference numerals are given to those components that are like or the same as the corresponding components of the second embodiment.

Like the second embodiment, the external connector60of the third embodiment includes an external connecting terminal61, a coil holding portion62, and a terminal holding portion64, which are formed integrally, a shown inFIG. 3. The filter coil27and the filter capacitors28are integrated with the external connector60through molding. A connecting member63, which is integrated with the terminal holding portion64, is electrically connected with the circuit board25.

In addition to the advantages of the second embodiment, the third embodiment has the following advantage.

(11) The board connector32is integrated with the external connector60. Therefore, most of the components accommodated in the circuit accommodating space21, that is, most of the components about the circuit board25, are integrated. This permits the inverter unit22to be easily installed in the electric compressor10.

The present embodiments may be modified as follows.

In the first embodiment, the board connector32may be integrated with the external connector40.

Only the filter capacitors may be integrated with an external connector though molding. A filter coil is mounted to the circuit board25in any manner as long as contact of the filter coil with any of the bottom wall12a, the circumferential wall12c, and the inverter cover20is prevented.

As long as the insulating property is maintained, the external connectors40,50,60do not need to be formed of resin. For example, ceramics may be used as necessary.