Capacitor unit and its manufacturing method

1. A capacitor unit comprising:

a plurality of capacitors arranged side by side, each capacitor including an end face electrode at one end face and a side face electrode at a side face, the side face electrode having a polarity different from the end face electrode;

a plurality of bus bars, each bus bar being connected to the end face electrode of one of the capacitors and the side face electrode of an adjacent one of the capacitors;

a circuit substrate arranged at a side of the plurality of capacitors having the end face electrodes; and

a plurality of conductive portions electrically connecting the bus bars to the circuit substrate, the conductive portions extending from the bus bars, respectively, toward the circuit substrate.

2. The capacitor unit of claim 1 , wherein each bus bar includes a bending portion arranged near the end face electrode of the one of the capacitors to which the bus bar is connected.

3. The capacitor unit of claim 1 , further comprising:

a first fixing case and a second fixing case for holding the capacitors parallel to each other;

a plurality of bus bar holes arranged at an upper surface of the first fixing case for inserting a connecting portion of each bus bar toward the side face electrode of a respective one of the capacitors; and

a through-hole formed at a position facing the connecting portion at a side surface of the first fixing case when the connecting portion is inserted to the bus bar hole,

wherein one end of each capacitor is inserted into the first fixing case and the other end of each capacitor is inserted into the second fixing case.

4. A capacitor unit comprising:

a plurality of power accumulating elements, each power accumulating element having a columnar shape, and each power accumulating element including an end face electrode arranged at one end face of the columnar shape and a side face electrode arranged at a side face of the columnar shape;

a bus bar weld-connected to the side face electrode of one of the power accumulating elements other than power accumulating elements having the side face electrode of either highest voltage value or lowest voltage value when the plurality of power accumulating elements are aligned and electrically and mechanically connected with respect to each other, and weld-connected to the end face electrode of the adjacent one of the power accumulating elements;

a lower case in which a bottom part of at least one of the power accumulating elements is inserted, the lower case being integrally formed with at least one elastic portion which contacts the bottom part; and

an upper case in which an upper part of at least one of the power accumulating elements is inserted,

wherein a displacement range of the elastic portion is greater than an error of height of the plurality of power accumulating elements.

5. The capacitor unit of claim 4 , further comprising:

two fixation screws; and

a fixing rod having a female screw at both ends thereof,

wherein each of the upper case and the lower case includes a fixation screw hole, and

wherein the upper case and the lower case are connected and fixed by inserting the fixation screws through the fixation screw holes, respectively, and fastening the fixation screws to the fixing rod.

6. The capacitor unit of claim 4 , wherein the upper case has a plurality of contacting portions, and the side faces of the power accumulating elements contact the contacting portions, respectively.

7. A capacitor unit comprising:

a plurality of capacitors each having a columnar shape, each capacitor having an electrode arranged at both end faces of the columnar shape;

an internal bus bar weld-connected such that the electrodes are in series, in parallel, or in series parallel;

a plurality of capacitor blocks each including an upper case and a lower case for holding the capacitors, an upper end face of each capacitor being inserted into one of the upper cases and a lower end face of each capacitor being inserted into one of the lower cases; and

an external bus bar electrically connecting two adjacent capacitor blocks by fixing the external bus bar to electrodes positioned at ends of the two adjacent capacitor blocks,

wherein the external bus bar has a first portion contacting a second portion of the electrodes positioned at ends of the two adjacent capacitor blocks, and

wherein a projection is formed on the first portion and/or the second portion.

8. The capacitor unit of claim 7 , wherein the electrodes positioned at ends of the two adjacent capacitor blocks are the electrodes at end faces of the capacitors.

9. The capacitor unit of claim 7 , wherein the electrodes positioned at ends of the two adjacent capacitor blocks are extraction electrodes, and the extraction electrodes are connected to the electrodes at end faces of the capacitors.

10. The capacitor unit of claim 7 , wherein projections are formed on a contact surface of the external bus bar and a contact surface of the electrodes positioned at ends of the two adjacent capacitors for reducing relative movement between the external bus bar and the electrodes positioned at ends of the two adjacent capacitors.

11. The capacitor unit of claim 10 , wherein the electrodes positioned at ends of the two adjacent capacitor blocks are the electrodes at end faces of the capacitors.

12. The capacitor unit of claim 10 , wherein the electrodes positioned at ends of the two adjacent capacitor blocks are extraction electrodes, and the extraction electrodes are connected to the electrodes at end faces of the capacitors.