Fastening structure

1. A fastening structure comprising:

a metallic fastening part for fastening a first metal member and a second metal member to each other, wherein the fastening part is

a combination body of:

a male screw shaft portion installed upright at the second metal member and passing through an attachment through-hole provided in the first metal member, and

a nut having a female screw hole portion that engages with the male screw shaft portion, and a larger-diameter portion whose diameter is larger than an outer diameter of the male screw shaft portion, or

a combination body of:

a female screw hole portion provided in the second metal member, and

a bolt having a male screw shaft portion, which engages with the female screw hole portion and passes through the attachment through-hole provided in the first metal member, and a larger-diameter portion whose diameter is larger than the outer diameter of the male screw shaft portion; and

an insulating member for electrically insulating the fastening part and the first metal member from each other, and the first metal member and the second metal member from each other,

wherein the insulating member includes:

an annular insulating part including an inner-diameter hole which allows passing through of the male screw shaft portion of the fastening part, and electrically insulating between the first metal member and an entire surface of an outer periphery of the male screw shaft portion of the fastening part, and between the first metal member and an entire surface of an outer periphery of the larger-diameter portion of the fastening part, and

a plate-like insulating part including a corresponding inner-diameter hole which corresponds to the inner-diameter hole of the annular insulating part and allows passing through of the male screw shaft portion of the fastening part, and electrically insulating between the first metal member and the second metal member, and

wherein the first metal member is disposed on an upper surface of the plate-like insulating part, and the second metal member is disposed on a bottom-most surface of the plate-like insulating part.

2. The fastening structure claim 1 , further comprising a reservoir gap capable of storing a liquid form of water, between the first metal member and a portion covering an entire surface of an outer periphery of at least the larger-diameter portion of the annular insulating part.

3. The fastening structure 1 , wherein the corresponding inner-diameter hole comprises a larger-diameter hole and a smaller-diameter hole,

the larger-diameter hole is a hole fitted into the annular insulating part, and

the smaller-diameter hole is a hole which allows the male screw shaft portion to pass through.

4. The fastening structure 1 , wherein the inner-diameter hole comprises an upper inner-diameter hole which has an inner diameter accommodating a larger-diameter portion of the bolt or a larger-diameter portion of the nut, and a lower inner-diameter hole has an inner diameter through which the male screw shaft portion of the bolt passes.

5. The fastening structure 1 , wherein a tip end of the male screw shaft portion is provided with a male screw portion engaging with the female screw hole portion.

6. A cell pack using the fastening structure according to claim 1 , the cell pack comprising:

a battery module including a plurality of cells;

the first metal member; and

the second metal member,

wherein the second metal member is an installation substrate on which the battery module is installed, and the first metal member is an attachment member disposed between the battery module and the installation substrate.

7. The cell pack according to claim 6 , wherein the attachment member is disposed between the plurality of battery modules and the installation substrate, and holds the plurality of battery modules.