Patent Description:
A power conversion unit is provided, in a chassis, with a power conversion module configured by an inverter and performing conversion between direct current power and alternating current power. The power conversion module has a bus bar (first bus bar) inputting and outputting direct current power and alternating current power. The first bus bar and a bus bar (second bus bar) provided in an external device are fastened to each other on a terminal which is a connection base.

For example, a power conversion unit disclosed in <CIT> is configured integrally with an external device which is a motor, and in the power conversion unit, first bus bars of a power conversion module and second bus bars of the external device are fastened to each other on a terminal formed of a resin. The terminal is fixed to a metal chassis dividing the power conversion unit and the external device with a bolt or the like.

According to the technique of <CIT>, in order to secure the insulation between the bus bars fixed onto the terminal and the metal chassis fixed to a lower portion of the terminal, the terminal needs to be increased in size such that the distance between the bus bars and the metal chassis is sufficiently large. Moreover, a space for fastening the terminal and the metal chassis with a bolt or the like is required in the power conversion unit, which poses a problem of an increase in size of the power conversion unit. Prior art document <CIT>refers to an electric connection box which includes a housing in which a containing space is provided, and a first substrate unit and a second substrate unit which are contained in the containing space and output power input from a power source on the outside of the housing with respect to a load. The first substrate unit includes a first power source input terminal including a first terminal exposed portion, and the second substrate unit includes a second power source input terminal including a second terminal exposed portion. The first terminal exposed portion and the second terminal exposed portion are fastened by a fastening member and are electrically connected along with a power source connection terminal at least a part of which is exposed to the outside of the housing and which is connected to the power source, in a state where the first and second substrate units are contained in the housing. Prior art document <CIT> discloses a proposes an in-vehicle power conversion device that includes a drive unit, a casing and a plurality of busbars. The drive unit converts and transmits electric power. The casing includes electrical input-output parts and a main body. The main body includes a housing portion that houses the drive unit, and a lid body that closes the housing portion. The busbars electrically connect the drive unit and the electrical input-output parts of the casing to and from which electric power is input and output. The electrical input-output parts are routed outside of the casing. The busbars have heat-dissipating portions that are arranged along the casing to transfer heat to the casing outside of the housing portion.

The present invention has been made in order to solve such a problem. It is an object to reduce the size of the power conversion unit.

The object underlying the present invention is achieved by a power conversion unit according to independent claim <NUM>. Preferred embodiments are defined in the respective dependent claims. According to one embodiment of this invention, a power conversion unit has a power conversion module performing conversion between direct current power and alternating current power; a first bus bar connected to the power conversion module and inputting and outputting the power; a chassis housing the power conversion module and the first bus bar; and a terminal connecting the first bus bar and a second bus bar connected to an external device. The terminal and at least a part of the chassis are integrally formed of a resin.

A power conversion unit according to embodiments of the present invention is described.

<FIG> is an exploded perspective view of a power conversion unit of a first embodiment. In this figure, a direction from the left to the right in the figure is referred to as an X axis, a direction from the right deep side to the front left side in the figure is referred to as a y axis, and a direction from the bottom to the top in the figure is referred to as a Z axis.

A power conversion unit <NUM> configures an integrated unit with an external device <NUM>. For example, when the external device <NUM> is a motor, a motor unit is configured by the power conversion unit <NUM> and the external device <NUM>.

The power conversion unit <NUM> has a power conversion module <NUM>, first bus bars <NUM> connected to terminals of the power conversion module <NUM>, a chassis <NUM> housing the power conversion module <NUM>, a terminal <NUM> connecting bus bars, second bus bars <NUM> connected to terminals of the external device <NUM>, and a shield <NUM> suppressing noise between the power conversion unit <NUM> and the external device <NUM>.

The power conversion module <NUM> is configured by an inverter and performs conversion between direct current power and alternating current power. For example, the power conversion module <NUM> converts direct current power input from a battery (not illustrated) to alternating current power, and then outputs the converted alternating current power to the external device <NUM>. This figure illustrates two bus bars on an output side but three or more bus bars may be provided as bus bars on the output side. The terminals of the power conversion module <NUM> are connected to first bus bars 20A, 20B by fastening by first bolts 21A, 21B. The power conversion module <NUM> is fixed to the upper surface of a bottom portion <NUM> of the chassis <NUM>.

The chassis <NUM> contains the bottom portion <NUM> formed of a resin and a box portion <NUM> formed of a metal. The bottom portion <NUM> is formed of an engineering plastic resin, such as polyamide, for example. The box portion <NUM> is manufactured by die casting using a metal material, such as aluminum. The box portion <NUM> is fixed to the bottom portion <NUM> to cover the power conversion module <NUM> and the terminal <NUM> provided on the bottom portion <NUM>.

The terminal <NUM> is formed of a resin and is configured integrally with the bottom portion <NUM> of the chassis <NUM>. The terminal <NUM> connects the first bus bars 20A, 20B connected to the power conversion module <NUM> and second bus bars 50A, 50B connected to the external device <NUM> by fastening by second bolts 51A, 51B on the terminal <NUM>.

The first bus bars 20A, 20B and the second bus bars 50A, 50B are plate-like metal members containing tough pitch copper or the like. The second bus bars 50A, 50B each are configured into an L shape having a bent portion. The first bus bars 20A, 20B and the second bus bars 50A, 50B are provided with bolt holes through which bolts pass in the fastening by the bolts in the vicinity of both ends thereof.

The power conversion module <NUM> and the terminal <NUM> are provided with screw grooves screwable to the first bolts 21A, 21B and the second bolts 51A, 51B.

In the first bus bars 20A, 20B, due to the fact that the first bolts 21A, 21B provided to pass through the bolt holes provided in left portions of the first bus bars 20A, 20B in the figure are screwed to the screw grooves of the power conversion module <NUM>, the first bus bars 20A, 20B are fastened to the power conversion module <NUM>. End portions on the right side (x-axis positive direction side) of the figure of the first bus bars 20A, 20B and end portions on the left side (x-axis negative direction side) of the figure of the second bus bars 50A, 50B are stacked such that the bolt holes provided in both of the first bus bars 20A, 20B and the second bus bars 50A, 50B are overlapped with each other. Then, the second bolts 51A, 51B are passed through the bolt holes of the first bus bars 20A, 20B and the bolt holes of the second bus bars 50A, 50B disposed in an overlapping manner to be screwed to the screw grooves of the terminal <NUM>. Thus, the first bus bars 20A, 20B and the second bus bars 50A, 50B are fastened to each other.

The shield <NUM> is formed of a metal, such as iron or aluminum, and is manufactured by combining a press method and welding as appropriate. The shield <NUM> is fixed to cover the undersurface of the bottom portion <NUM> and shields noise propagating between the power conversion module <NUM> and the external device <NUM>. The shield <NUM> is provided with openings 61A, 61B. The second bus bars 50A, 50B pass through the openings 61A, 61B to reach the external device <NUM> side.

The external device <NUM> has a recessed portion <NUM> having an opening in the upper surface (surface on the z-axis positive direction side). In the recessed portion <NUM>, the second bus bars 50A, 50B are electrically connected to the external device <NUM>.

<FIG> is a cross-sectional view in an xz plane of the power conversion unit <NUM> along the first bus bar 20A and the second bus bar 50A.

According to this figure, the L-shaped second bus bar 50A passes through the opening 61A of the shield <NUM> to extend into the recessed portion <NUM> of the external device <NUM>. The second bus bar 50A is fastened to a connection terminal <NUM> provided in the recessed portion <NUM> by a third bolt <NUM> to be electrically connected to the connection terminal <NUM>.

As a comparative example, an example in which the terminal <NUM> and the bottom portion <NUM> of the chassis <NUM> are separately formed is described.

<FIG> is a cross-sectional view of the power conversion unit <NUM> in the xz plane in the comparative example. The terminal <NUM> and the bottom portion <NUM> are separately provided. The bottom portion <NUM> is formed of a metal as with the box portion <NUM>.

As illustrated in this figure, the terminal <NUM> has a flange <NUM> provided with a bolt hole. A fourth bolt <NUM> passes through the hole of the flange <NUM> to be screwed to a screw groove provided in the bottom portion <NUM>, so that the terminal <NUM> is fixed to the bottom portion <NUM>. Due to such a configuration, the power conversion unit <NUM> increases in length in the x-axis direction corresponding to the width of the flange <NUM> used for the fastening by the fourth bolt <NUM>.

Although not illustrated, a terminal is separately provided also on an input side of the power conversion module <NUM>. This terminal is formed of a resin integrally with the terminal <NUM> and the bottom portion <NUM>.

The first embodiment configured as described above can obtain the following effects.

In the power conversion unit <NUM> of the first embodiment, the first bus bars 20A, 20B connected to the power conversion module <NUM> and the second bus bars 50A, 50B connected to the external device <NUM> are connected to each other on the terminal <NUM>. Both the terminal <NUM> and the bottom portion <NUM> of the chassis <NUM> are integrally formed of a resin.

When the bottom portion <NUM> and the terminal <NUM> are separately configured as in the comparative example illustrated in <FIG>, the terminal <NUM> needs to have the flange <NUM> used for the fastening by the fourth bolt <NUM> in order to fix the terminal <NUM> to the bottom portion <NUM>. Therefore, the power conversion unit <NUM> increases in size corresponding to the width (x-axis direction) of the flange <NUM>.

Whereas, in this embodiment, the terminal <NUM> and the bottom portion <NUM> are integrally formed. Therefore, the flange <NUM> which is a configuration fastening the terminal <NUM> and the bottom portion <NUM> as in the comparative example becomes unnecessary, which enables a reduction in the size of the power conversion unit <NUM>. Furthermore, the fastening by the fourth bolt <NUM> in the flange <NUM> of the terminal <NUM> becomes unnecessary, which simplifies the configuration, and thus the component cost and the manufacturing cost can be reduced.

Moreover, by resinifying the bottom portion <NUM>, the distance between the first bus bars 20A, 20B and the second bus bars 50A, 50B fastened to each other on the terminal <NUM> and the bottom portion <NUM> is sufficiently large, which eliminates the necessity of considering the insulation as compared with the case where the bottom portion <NUM> is formed of a metal, and therefore the terminal <NUM> can be reduced in size. Moreover, due to the fact that the bottom portion <NUM> is configured using a resin, a reduction in the thickness and weight of the bottom portion <NUM> can be achieved.

The first embodiment illustrates an example in which the terminal <NUM> is disposed on a side where the power conversion module <NUM> is provided with respect to the bottom portion <NUM> of the chassis <NUM>, i.e., upper surface side (z-axis positive direction side) of the bottom portion <NUM>, and disposed inside the box portion <NUM> of the chassis <NUM>. The elucidation of the technical background of the present invention describes an example in which the terminal <NUM> is disposed on a side where the external device <NUM> is provided with respect to the bottom portion <NUM>, i.e., undersurface side (z-axis negative direction side) of the bottom portion <NUM>, and disposed outside the box portion <NUM>.

<FIG> is a cross-sectional view of the xz plane of the power conversion unit <NUM> for elucidating the technical background of the present invention.

The terminal <NUM> is provided integrally with the bottom portion <NUM> on a side (z-axis negative side) where the external device <NUM> is provided with respect to the bottom portion <NUM>. The shield <NUM> has an opening <NUM> having a cross section substantially equal to that of the terminal <NUM>. The terminal <NUM> passes through the opening <NUM> of the shield <NUM> to be located in the recessed portion <NUM> of the external device <NUM>.

The first bus bar 20A is configured into an L shape having a bent portion. In the recessed portion <NUM>, the first bus bar 20A and the second bus bar 50A are fastened to the terminal <NUM> by the second bolts <NUM>.

The following effects can be obtained by the second embodiment configured as described above.

According to the power conversion unit <NUM> for elucidating the technical background of the present invention, the power conversion module <NUM> and the terminal <NUM> are disposed on opposite sides with respect to the bottom portion <NUM>, i.e., disposed outside the box portion <NUM>. Therefore, as compared with the first embodiment illustrated in <FIG>, the power conversion module <NUM> and the terminal <NUM> can be disposed close to each other in the longitudinal direction (x-axis direction) in the surface of projection in the thickness direction (z-axial direction) of the bottom portion <NUM>, and thus the power conversion unit <NUM> can be reduced in size.

According to the power conversion unit <NUM> for elucidating the technical background of the present invention, the terminal <NUM> provided on the undersurface (surface on the z-axis negative direction side) of the bottom portion <NUM> is housed in the recessed portion <NUM> of the external device <NUM> when an integrated unit of the power conversion unit <NUM> and the external device <NUM> is configured. When such an integrated unit is assembled, the first bus bars <NUM> and the second bus bars <NUM> connected to the external device <NUM> can be fastened to each other using the second bolts <NUM> in a state where the chassis <NUM> is configured by connecting the bottom portion <NUM> and the box portion <NUM>. Therefore, when the power conversion unit <NUM> and the external device <NUM> are connected to each other, the chassis <NUM> is already assembled. Hence, the entrance of foreign substances, such as wastes or dust, into the power conversion unit <NUM> can be prevented and the handling is facilitated, so that a manufacturing process can be simplified.

The first embodiment and the above for elucidation of the technical background of the present invention describe examples in which nothing is provided between a first bus bar 20A and a first bus bar 20B and between the second bus bar 50A and the second bus bar 50B. A third embodiment describes an example in which an insulating member containing a resin is provided between the first bus bar 20A and the first bus bar 20B and between the second bus bar 50A and the second bus bar 50B.

<FIG> is a perspective view of a part of a power conversion unit <NUM> for elucidating the technical background of the present invention.

<FIG> is a figure of the power conversion unit <NUM> viewed from the y-axis positive direction side.

<FIG> is a figure of the power conversion unit <NUM> viewed from the x-axis positive direction side.

As illustrated in these figures, a notch <NUM> extending in the z-axis direction is provided in a corner portion in the plane in the xy direction of the bottom portion <NUM>. The terminal <NUM> is provided to be flush with the inner surface in the y-axis direction of the notch <NUM>.

The first bus bar 20A is configured by bending of a plate-like member having bending portions with equal widths at the bending portions and has a first bus bar 20Ax extending in the x-axis direction, a first bus bar 20Ay extending in the y-axis direction, a first bus bar 20Az extending in the z-axis direction, and a first bus bar fastening portion 20Af provided in the xz-plane direction. The first bus bar fastening portion 20Af is provided with a bolt hole through which the second bolt 51A passes.

The first bus bar 20B has a first bus bar 20Bx extending in the x-axis direction, a first bus bar 20By extending in the y-axis direction, a first bus bar 20Bz extending in the z-axis direction, and a first bus bar fastening portion 20Bf provided in the xz-plane direction. The first bus bar fastening portion 20Bf is provided with a bolt hole through which the second bolt 51B passes.

The first bus bar fastening portion 20Af and the second bus bar 50A are fastened to each other by the second bolt 51A. The first bus bar fastening portion 20Bf and the second bus bar 50B are fastened to each other by the second bolt 51B.

Between the first bus bar 20A and the first bus bar 20B, a wall portion <NUM> is provided. The wall portion <NUM> is formed of a resin integrally with the bottom portion <NUM> and the terminal <NUM>. The wall portion <NUM> has a wall portion 80x extending in the x-axis direction, a wall portion 80y extending in the y-axis direction, and a wall portion 80z extending in the z-axis direction.

The first bus bar 20Ax and the first bus bar 20Bx adjacent to each other in the y-axis direction are insulated by the wall portion 80x extending in the x-axis direction and having a height in the z-axis direction. The first bus bar 20Ay and the first bus bar 20By adjacent to each other in the x-axis direction are insulated by the wall portion 80y extending in the y-axis direction and having a height in the z-axis direction. The first bus bar 20Az and first bus bar 20Bz adjacent to each other in the x-axis direction are insulated by the wall portion 80z extending in the z-axis direction and having a width in the y-axis direction.

The following effects can be obtained by the third embodiment configured as described above.

The power conversion unit <NUM> for elucidating the technical background of the present invention is provided with the wall portion <NUM> formed integrally with the terminal <NUM> and the bottom portion <NUM> of the chassis <NUM>. The wall portion <NUM> insulates between the first bus bar 20A and the first bus bar 20B and between the second bus bar 50A and the second bus bar 50B. The above-described configuration can reduce a possibility of the contact between the first bus bar 20A and the first bus bar 20B and the contact between the second bus bar 50A and the second bus bar 50B due to an impact, unexpected adhesion of a conductive member, or the like as compared with a case where the wall portion <NUM> is not provided.

Furthermore, the wall portion <NUM> is formed of a resin integrally with the bottom portion <NUM> and the terminal <NUM>, and therefore the degree of freedom of arrangement is high. Hence, the wall portion <NUM> can be disposed at a desired place between the power conversion module <NUM> and the terminal <NUM> without being limited to the vicinity of fastened points by the second bolts 51A, 51B.

Furthermore, the fastening by the second bolts 51A, 51B is performed in a state where the second bolts 51A, 51B are pressed against the terminal <NUM> in the y-axis negative direction. However, the terminal <NUM> is further configured integrally with the wall portion <NUM>, and therefore the strength of the terminal <NUM> is increased, and thus manufacturing defects can be reduced. Specifically, the strength in the y-axis direction of the terminal <NUM> can be increased due to the fact that the terminal <NUM> is integrated with the wall portion 80z having a width in the y-axis direction.

The above description presents examples in which the power conversion module <NUM> is air-cooled but the present invention is not limited thereto. Another elucidation of the technical background of the present invention describes an example in which a refrigerant flow path is provided in the bottom portion <NUM> of the chassis <NUM> or the like and the power conversion module <NUM> is cooled with a refrigerant.

<FIG> is a cross-sectional view in the xz plane of the power conversion unit <NUM> for elucidating the technical background of the present invention.

As illustrated in this figure, the bottom portion <NUM> of the chassis <NUM> and the terminal <NUM> are provided with a refrigerant flow path <NUM> configured integrally therewith. More specifically, a first flow path <NUM> having a thickness in the z direction and provided in the xy plane direction in the bottom portion <NUM> and a second flow path <NUM> provided to extend in the z-axis direction in the terminal <NUM> and the bottom portion <NUM> are provided. The flow path <NUM> is connected to an inflow port (not illustrated) and an outflow port (not illustrated) communicating with the outside of the chassis <NUM> and the terminal <NUM> and is configured to be able to circulate a refrigerant between the chassis <NUM> and the terminal <NUM> and a cooling device (not illustrated) provided outside through the inflow port and the outflow port. Due to the fact that the flow path <NUM> is configured as described above, the power conversion module <NUM> is cooled through the upper surface of the bottom portion <NUM> and the first bus bars 20A, 20B and the second bus bars 50A, 50B are cooled through the terminal <NUM>.

<FIG> is a cross-sectional view of the power conversion unit <NUM> of a comparative example. In this comparative example, the bottom portion <NUM> is provided as a separate metal body as with the comparative example illustrated in <FIG>. Since the bottom portion <NUM> is formed of a metal, it is difficult to provide the first flow path <NUM> inside the bottom portion <NUM>. Therefore, an opening or a groove is formed to contact the bottom surface of the power conversion module <NUM> in the upper surface (surface on the z-axis positive direction side) of the bottom portion <NUM>. The opening or the groove is used as the first flow path <NUM>. In the interface between the power conversion module <NUM> and the bottom portion <NUM>, a sealing member <NUM> is provided to surround the flow path <NUM> in order to prevent the leakage of a refrigerant. Whereas, in this embodiment, due to the fact that the first flow path <NUM> is provided inside the bottom portion <NUM> and the terminal <NUM> which are integrally configured, the sealing member <NUM> is not required.

The following effects can be obtained by the fourth embodiment configured as described above.

According to the power conversion unit <NUM> illustrated in the fourth embodiment, due to the fact that the bottom portion <NUM> is formed of a resin integrally with the terminal <NUM>, it becomes relatively easy to provide the flow path <NUM> inside the bottom portion <NUM> and the terminal <NUM> as compared with the case where the bottom portion <NUM> is formed of a metal.

Moreover, as compared with the comparative example of <FIG> in which the bottom portion <NUM> has the first flow path <NUM> opened to the upper surface, the sealing member <NUM> is not required, so that the configuration can be simplified. Moreover, the necessity of bringing the flow path <NUM> into contact with the power conversion module <NUM> is eliminated, so that the degree of freedom in design of the flow path <NUM> can be improved.

Moreover, heat transmitted from the external device <NUM> is cooled in the terminal <NUM> before reaching the power conversion module <NUM> which is a precision instrument through the second bus bars <NUM>. Therefore, the power conversion unit <NUM> having a high permissible limit temperature and high performance and the external device <NUM> having a large heat generation amount and a high output can be combined. Hence, an improvement of the performance of a unit containing the power conversion unit <NUM> and the external device <NUM> can be realized.

In the preceding elucidation, the bottom portion <NUM> of the chassis <NUM> and the terminal <NUM> are provided with the flow path <NUM> configured integrally therewith but the present invention is not limited thereto. A first modification describes another configuration of the flow path <NUM>.

According to this figure, the second flow path <NUM> provided in the terminal <NUM> is omitted as compared with the fourth embodiment illustrated in <FIG>. The first flow path <NUM> provided in the bottom portion <NUM> is extended to the vicinity of the terminal <NUM>, and therefore the terminal <NUM> formed integrally with the bottom portion <NUM> is cooled, so that an increase in the temperature of the first bus bars 20A, 20B is suppressed.

According to the power conversion unit <NUM> of such a modification, even when the second flow path <NUM> illustrated in <FIG> is not provided in the terminal <NUM>, the terminal <NUM> is cooled by the first flow path <NUM> extended to the vicinity of the terminal <NUM>. Therefore, the configuration of the terminal <NUM> can be simplified and an improvement of the performance of an integrated unit by blocking of the heat conduction between the power conversion unit <NUM> and the external device <NUM> can be achieved.

The preceding elucidation describes an example in which the terminal <NUM> does not have the second flow path <NUM>. A second modification describes another configuration in a case where the terminal <NUM> does not have the second flow path <NUM>.

<FIG> is a cross-sectional view in the xz plane of the power conversion unit <NUM> of this modification.

According to this figure, a metal body <NUM> reaching the inside of the first flow path <NUM> is provided in the terminal <NUM> as compared with the first modification illustrated in <FIG>.

Claim 1:
A power conversion unit (<NUM>),
comprising:
- a power conversion module (<NUM>) performing conversion between direct current power and alternating current power;
- a first bus bar (20A, 20B) connected to the power conversion module (<NUM>) and inputting and outputting the power;
- a chassis (<NUM>) housing the power conversion module (<NUM>) and the first bus bar (20A, 20B); and
- a terminal (<NUM>) provided inside the chassis (<NUM>), fastened to the first bus bar (20A, 20B), and connecting the first bus bar (20A, 20B) and a second bus bar (50A, 50B) connected to an external device (<NUM>),
wherein the terminal (<NUM>) and at least a part of the chassis (<NUM>) are integrally formed of a resin.