Sealed terminal device for motor-driven compressor

A sealed terminal device for a motor-driven compressor has an electrically insulating terminal holder (12) to be attached to the housing wall (2a) of the motor-driven compressor, a plurality of sealed terminals (18) held in the terminal holder (12), for penetrating the housing wall (2a) with play to the housing wall (2a), and a groove (40) or cavity (38) formed in the terminal holder (12) to increase a creepage distance for insulation between the sealed terminals.

RELATED APPLICATIONS

This is a U.S. National Phase Application under 35 USC §371 of International Application PCT/JP2007/1062709 filed on Jun. 25, 2007.

This application claims the priority of Japanese patent application no. 2006-190200 filed Jul. 11, 2006, the content of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a motor-driven compressor incorporating an electric motor, and particularly relates to a sealed terminal device for establishing electrical connection between an electric motor and an external device.

BACKGROUND ART

This kind of motor-driven compressor includes a housing, and a compressing unit and an electric motor which are accommodated in the housing (Patent Document 1). The compressing unit is driven by the electric motor, and performs a series of processes from the suction of a working fluid, compression, and discharge.

The compressor further includes a sealed terminal device for establishing electric connection between the electric motor and an external device, and the sealed terminal device includes a plurality of sealed terminals. These sealed terminals penetrate the wall of the housing airtightly, and each have both end portions projecting into and outside the housing.

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

The aforementioned sealed terminals are fixed to the wall of the housing via glass and metal holders, and this glass maintains the interior of the housing airtight while electrically insulating between the sealed terminals and metal holders and between the sealed terminals and the wall of the housing.

However, to secure the adhesion between the metal holders and glass, the use of glass not only requires the process of plating nickel on the metal holders, but also needs a lot of works to fix the metal holders and the sealed terminals. In case of the sealed terminal device using glass, therefore, it is not easy to attach the sealed terminal device to the wall of the housing.

Since electric insulation between the sealed terminals is established with glass alone, if the distance between the sealed terminals is short, electric insulation between the sealed terminals decreases. Therefore, it is not easy to miniaturize a sealed terminal device using glass.

It is an object of the present invention to provide a sealed terminal device for a motor-driven compressor which facilitates attachment of a sealed terminal while sufficiently securing electric insulation between the sealed terminal and the surrounding thereof, and which can be miniaturized as a whole.

Means for Solving the Problems

To achieve the object, a sealed terminal device according to the present invention comprises a terminal holder to be attached to a wall of the housing and including internal and external holder half bodies which have electric insulation and sandwiching the wall, a plurality of sealed terminals held in the terminal holder, for penetrating the wall with play thereto and having both end portions to be electrically connected to the electric motor and an external device, seal members for sealing between the wall and the terminal holder and between the terminal holder and the sealed terminals, respectively and an insulating element for increasing a degree of electric insulation between the sealed terminal and a surrounding thereof.

Because the sealed terminal device has the seal members and the insulating element separately, it is possible to sufficiently secure electric insulation between the sealed terminal and the surrounding thereof while securing sufficient sealing of the sealed terminal device. Therefore, the sealed terminal device according to the invention can shorten the distance needed between the sealed terminals, thus as a whole making the miniaturization possible.

Specifically, the insulating element can include an area formed in the terminal holder to increase a creepage distance for insulation of at least one of between the sealed terminals and between the wall and the sealed terminals. In this case, the area can have a groove formed in an outer surface of the terminal holder, and extending between the sealed terminals and/or a cavity formed in the terminal holder. Such a groove and cavity increase the creepage distance for insulation between the sealed terminals and between the sealed terminal and the wall of the housing, thus improving the degree of electric insulation of the sealed terminals to the surrounding.

It is preferable that the groove should extend in a radial direction of the terminal holder, and the cavity should be positioned to surround the sealed terminals and adjacent to the wall.

Further, the insulating element can include an electric insulation barrier intervened between the sealed terminals, and the electric insulation barrier has an electrical insulation layer formed on an outer surface of the sealed terminal. In this case, it is preferable that the electrical insulation layer should cover an entire outer surface of the sealed terminal except for both the end portions of the sealed terminal. Such an electrical insulation layer increases the degree of electric insulation between the sealed terminals as well as between the sealed terminals and the wall of the housing.

When the motor-driven compressor is used to compress a refrigerant in a refrigeration circuit, the electrical insulation layer ensures the direct contact of the refrigerant to the sealed terminals. Therefore, short-circuiting between the sealed terminals and the surrounding via the refrigerant does not occur. Further, the insulating element can include an insulating sleeve to fill in the play between the wall of the housing and the sealed terminal.

It is preferable that the sealed terminal should also serve as a fastening bolt to attach the terminal holder to the wall of the housing. In this case, it becomes easy to attach the terminal holder to the wall of the housing.

Specifically, it is preferable that the sealed terminal should further include a rod having one end to be positioned on the electric motor side and the other end to be positioned on the external device side, a flange formed on the rod for sandwiching one of the holder half bodies between the flange and the wall, and a fastening nut attached to the other end of the rod to fasten the other one of the holder half bodies between the nut and the wall of the housing. In this case, it is preferable that the terminal holder should further include a stopper surface which makes a lock for the sealed terminal.

Effect of the Invention

Because the sealed terminal device for a motor-driven compressor according to the present invention has the seal members and the insulating element separately, it is possible to miniaturize the sealed terminal device while sufficiently securing sealing of the sealed terminal device.

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 and 2respectively show motor-driven compressors to which the present invention is adapted. Each of the motor-driven compressors has a metal housing2, and a compressing unit4and an electric motor6which are accommodated in the housing2. The compressing units4ofFIGS. 1 and 2are shown as a scroll unit.

The compressor ofFIG. 1further has a power supply control board8accommodated in the housing2. The control board8includes an inverter to control power supply to the electric motor6, and driving of the electric motor6. More specifically, a partition wall9is disposed in the housing2ofFIG. 1, and separates the interior of the housing2into a room for accommodating the compressing unit4and electric motor6and a room for accommodating the control board8.

The compressor ofFIG. 2differs from the compressor ofFIG. 1in that it does not have the partition wall9. However, each of the motor-driven compressors ofFIGS. 1 and 2has a sealed terminal device10to electrically connect the electric motor6or the control board8to an electric device (not shown) outside the housing2, and the sealed terminal device10is attached to the housing wall of the housing2, which is the partition wall or the outer wall of the housing2.

FIGS. 3 to 5show the sealed terminal device10according to the first embodiment.

As shown inFIG. 3, the sealed terminal device10has a terminal holder12, which includes holder half bodies14and16. As apparent fromFIG. 4, each of the holder half bodies14and16has a triangular shape and is formed of an electrical insulation material, such as ceramics or a synthetic resin. In this embodiment, the material for the holder half bodies14and16is a synthetic resin.

The holder half bodies14and16are arranged sandwiching a housing wall2a. Specifically, the holder half body14is located on the electric motor6side, i.e., inward of the housing wall2a, and the holder half body16is located outward of the housing wall2a. The sealed terminal device10further has a plurality of, e.g., three, sealed terminals18which serve as fastening bolts to fasten the terminal holder12or the holder half bodies14and16to the housing wall2a.

More specifically, each sealed terminal18comprises a conductive rod member, and has a screw20at one end portion thereof, and a flange22at the other end portion thereof with a predetermined length secured between the flange22and the other end of the sealed terminal18. One end of each sealed terminal18is formed as an outside terminal end and the other end thereof is formed as an inside terminal end.

Further, three insertion holes24are formed in the terminal holder12, and are arranged at equal intervals in the circumferential direction of the terminal holder12.

Specifically, the three insertion holes24are respectively positioned at the corners of the triangular holder half body14,16, and penetrate the holder half bodies. Each insertion hole24has a recess26which is formed in the inner end face of the holder half body14. The recess26is larger in diameter than the insertion hole24, and can receive the flange22of the sealed terminal18inside.

Three through holes28are formed in the housing wall2a. The through holes28are arranged in correspondence to the through holes24of the terminal holder12, and have an inner diameter larger than the inner diameter of the insertion holes24.

As apparent fromFIG. 3, the terminal holder12is arranged with respect to the housing wall2ain such a way as to sandwich the housing wall2abetween the holder half bodies14and16, and each sealed terminal18is inserted into the corresponding insertion hole24and through hole28from the holder half body14side with its screw20as the head. The insertion of the sealed terminal18is stopped when the flange22abuts on the bottom of the corresponding recess26, at which time the screw20protrudes from the outer end face of the holder half body16.

Then, a nut30is screwed on the protruding screw20and the nut30is pressed against the holder half body16.

Accordingly, the holder half bodies14and16are fastened together with the housing wall2asandwiched between the flanges22of the sealed terminal18and the nut30, resulting completion of the attachment of the terminal holder12to the housing wall2a.

With the terminal holder12attached, the inner terminal end of each sealed terminal18protrudes from the inner end face of the terminal holder12, while its outer terminal end or the screw20protrudes from the outer end face of the terminal holder12. The inner terminal end is electrically connected to the electric motor6via a lead (not shown), while the screw20is electrically connected to the control board8via a lead (not shown).

As shown inFIG. 3, the holder half body14has an abutment face which abuts on the housing wall2a, and an annular groove31formed in the abutment surface. The annular groove31has a size to surround the three insertion holes24from outside, and extends along the periphery edge of the holder half body14. An O ring32is fitted in the annular groove31, and seals between the holder half body14and the housing wall2aairtightly.

Annular grooves33are formed in the bottoms of the individual recesses26, and surround the corresponding sealed terminals18. O rings34are respectively fitted in those annular grooves, and each O ring34is pushed against the bottom and inner wall of the annular groove33by the flange22of the sealed terminal18to seal between the corresponding sealed terminal18and the holder half body14airtightly. Therefore, when the motor-driven compressor is used to compress the refrigerant in the refrigeration circuit, the refrigerant does not leak out of the housing2through the sealed terminal device10.

As shown inFIG. 3, an insulating sleeve36is disposed in each through hole28of the housing wall2a, and the insulating sleeve36is positioned between the through hole2and the corresponding sealed terminal18to disconnect the electric connection between the sealed terminal18and the housing wall2a.

The terminal holder12further includes three cavities38corresponding to each sealed terminal18. The cavities38are recesses formed in the surface of the holder half body16which abuts on the housing wall2a, and are positioned adjacent to the housing wall2a.

Further, as shown inFIGS. 4 and 5, three grooves40are formed in the outer end face of the holder half body16, and extend between the sealed terminals18adjacent in the circumferential direction of the terminal holder12to the outer peripheral surface of the holder half body16in the radial direction thereof, and are aggregated at the center of the holder half body16. That is, the three grooves40form a Y shape. The one-dot chain line inFIG. 5shows the axial line of the sealed terminal18.

The grooves40lengthen the creepage distance for insulation between the adjoining sealed terminals18, and increase the degree of electric insulation between the sealed terminals18. In addition, the cavities38likewise lengthen the creepage distance for insulation between the sealed terminals18and the housing wall2a, and the creepage distance for insulation between the adjoining sealed terminals18, and further increase the degree of electric insulation between the sealed terminals18and the housing wall2a, and between the sealed terminals18. As a result, the distance between the sealed terminals18can be made shorter without reducing the electric insulation between the sealed terminals18, thus making it possible to make the sealed terminal device10compact.

Next, sealed terminal devices according to second and third embodiments will be described below; in describing the second and third embodiments, same reference numerals are given to those members and parts which exhibit the same functions as the members and parts of the first embodiment to omit their descriptions.

FIG. 6shows the sealed terminal device according to the second embodiment.

AlthoughFIG. 6shows only one sealed terminal18, the device of the second embodiment also has three sealed terminals18.

In the case of the second embodiment, each sealed terminal18has an electrical insulation layer42on its outer surface. The electrical insulation layer42covers the outer surface of the sealed terminal18in an area A inFIG. 6, excluding both end portions of the sealed terminal18, i.e., the aforementioned inner terminal end and outer terminal end.

Such an electrical insulation layer42can be formed by, for example, an insulating varnish applied to the area A of the sealed terminal18. When the sealed terminal18is formed of aluminum, the electrical insulation layer42can be formed by an aluminum oxide film obtained through an alumite treatment performed on the area A of the sealed terminal18.

FIG. 6also shows the connection between a connector44of a lead6aextending from the electric motor6and the inner terminal end of the sealed terminal18, and the connection between a lead8afrom the control board8and the outer terminal end of the sealed terminal18. The connector44overlaps the electrical insulation layer42when receiving the inner terminal end of the sealed terminal18, and the lead8ais pinched between the aforementioned nut30and a connector nut46.

The electrical insulation layer42serves as an electric insulation barrier positioned between the adjoining sealed terminals18, and increases the degree of electric insulation between the sealed terminals18. When the motor-driven compressor is used to compress the refrigerant of the refrigeration circuit, the electrical insulation layer42inhibits directly the contact of the outer surface of the sealed terminal18with the refrigerant. Therefore, the short-circuiting between the sealed terminals18and between the sealed terminals18and the housing wall2athrough the refrigerant does not occur, and the electric insulation of the sealed terminal device is improved significantly.

FIGS. 7 and 8show a sealed terminal device10according to the third embodiment.

The sealed terminal18of the third embodiment includes not only the aforementioned electrical insulation layer42but also a locking mechanism for the sealed terminal18. As apparent fromFIG. 8, the locking mechanism is realized by making the flange22of the sealed terminal18into a hexagonal shape, and making the recess26of the communicating hole24into an elliptical shape. The maximum diameter D of the flange22is larger than the width W of the recess26in the minor-axial direction, and the recess26has two flat inner wall surfaces26aalong the major axis, and the inner wall surfaces26aform a stopper surface which inhibits the rotation of the sealed terminal18.

The present invention is not restricted to the first to third embodiments, and various modifications are possible.

For example, the O ring32and the cavity38may be provided in each of the holder half bodies14and16.