Battery pack

Abstract

To provide a technology capable of suppressing damage to a battery cell housed in a cell case even when impact is applied to a lower case.SOLUTION: A battery pack includes an upper case, an outer case having a lower case fixed to the upper case, a battery cell, and a cell case that houses the battery cell. A clearance is provided between the lower case and the entire lower surface of the cell case.SELECTED DRAWING: Figure 19

Description

Technical Field

[0001] The technology disclosed by this specification relates to a battery pack.

Background Art

[0002] Patent Document 1 discloses a battery pack. The battery pack of Patent Document 1 includes an outer case including an upper case and a lower case fixed to the upper case, a battery cell, and a cell case for housing the battery cell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when a user drops the battery pack, an impact is applied to the lower case of the outer case, and the lower case may be deformed. In the case of the battery pack of Patent Document 1, when the lower case is deformed, the lower case comes into contact with the cell case, and the cell case may be deformed, which may damage the battery cell housed in the cell case.

[0005] This specification In the case where the battery pack drops or the like, on the bottom surface of the outer case, at a portion different from the protruding portion at the corner of the outer case when an impact is applied ru ko provides a technology capable of suppressing the above.

Means for Solving the Problems

[0006] The battery pack disclosed by this specification includes an outer case including an upper case and a lower case fixed to the upper case, a battery cell, and a cell case for housing the battery cell, and a clearance is provided between the entire lower surface of the lower case and the cell case.

[0007] In the battery pack described above, even if the lower case of the outer case is subjected to an impact and deformed, the lower case can be prevented from coming into contact with the underside of the cell case, thereby preventing damage to the battery cells housed in the cell case when an impact is applied to the lower case. [Brief description of the drawings]

[0008]

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[0009] In one or more embodiments, the cell case may be screwed to the outer case.

[0010] According to the above configuration, for example, when the user drops the battery pack, it is possible to suppress the displacement between the outer case and the cell case. Therefore, when an impact is applied to the lower case, it is possible to further suppress damage to the battery cells housed in the cell case.

[0011] In one or more embodiments, three or more battery cells may be arranged in parallel and housed in the lower case parallel to the bottom surface of the lower case. The three or more battery cells may be composed of an outer battery cell closest to the corner of the lower case and an inner battery cell provided inside the outer battery cell. The clearance between the first holding portion that holds the outer battery cell and the lower case among the lower surfaces of the cell case may be larger than the clearance between the second holding portion that holds the inner battery cell and the lower case among the lower surfaces of the cell case.

[0012] When the user drops the battery pack or the like, impacts are likely to be applied to the four corner portions of the bottom surface of the lower case of the outer case. That is, the four corner portions of the bottom surface of the lower case are most likely to be deformed. The distance between the first holding portion that holds the outer battery cell and the corner portion of the four corner portions of the bottom surface of the lower case where the distance to the outer battery cell is the shortest is shorter than the distance between the second holding portion that holds the inner battery cell and the corner portion of the four corner portions of the bottom surface of the lower case where the distance to the outer battery cell is the shortest. Therefore, when the four corner portions of the bottom surface of the lower case are deformed, the bottom surface of the lower case is more likely to come into contact with the first holding portion than the second holding portion. According to the above configuration, even when the four corner portions of the bottom surface of the lower case are deformed, it is possible to suppress the lower case from coming into contact with the lower surface of the cell case. Therefore, when an impact is applied to the lower case, it is possible to suppress damage to the battery cells housed in the cell case.

[0013] In one or more embodiments, the first holding portion may be composed of an end surface side holding portion that holds the end surface side in the longitudinal direction of the outer battery cell and a central side holding portion that holds the central side in the longitudinal direction of the outer battery cell. The clearance between the end surface side holding portion and the lower case may be larger than the clearance between the central side holding portion and the lower case.

[0014] The end surface side holding portion is closer to the four corner portions of the bottom surface of the lower case than the central side holding portion. According to the above configuration, even when the four corner portions of the bottom surface of the lower case are deformed, it is possible to suppress the lower case from coming into contact with the lower surface of the cell case. Therefore, when an impact is applied to the lower case, it is possible to suppress damage to the battery cells housed in the cell case.

[0015] In one or more embodiments, a step portion may be provided between the bottom surfaces of the lower case where the side surfaces of the outer battery cell and the side surfaces of the inner battery cell face each other. The step portion may slope downward from the inner battery cell side toward the outer battery cell side.

[0016] According to the above configuration, the clearance between the first holding portion and the lower case can be made larger than the clearance between the second holding portion and the lower case. Therefore, even if the four corners of the bottom surface of the lower case are deformed, the lower case can be prevented from contacting the underside of the cell case. Therefore, when an impact is applied to the lower case, damage to the battery cells housed in the cell case can be further prevented.

[0017] In one or more embodiments, the thickness of the four corners of the lower portion of the cell casing may be greater than the thickness of the cell casing below the longitudinal axis of the battery cell.

[0018] If the lower case is deformed, it is highly likely that the lower case will come into contact with the four corners of the lower part of the cell case. With the above configuration, it is possible to increase the strength of the parts of the cell case that are highly likely to come into contact with the lower case. Therefore, even if the lower case comes into contact with the cell case, damage to the battery cells housed in the cell case can be suppressed.

[0019] (First Example) The battery pack 2 of the embodiment will be described below with reference to the drawings. As shown in FIG. 24A , the battery pack 2 can be detachably attached to a power tool 200. While FIG. 24A illustrates an example in which the power tool 200 is an electric screwdriver, the power tool 200 may be, for example, an electric drill, an electric grinder, an electric circular saw, an electric chainsaw, an electric reciprocating saw, an electric lawn mower, an electric brush cutter, or an electric blower. When attached to the power tool 200, the battery pack 2 supplies power to the power tool 200. As shown in FIG. 25 , the battery pack 2 can be detachably attached to a charger 300. When attached to the charger 300, the battery pack 2 receives power from the charger 300. In the following description, when the battery pack 2 is attached to the power tool 200 or the charger 300, the direction in which the power tool 200 or the charger 300 is located as viewed from the battery pack 2 is referred to as "upward," and the opposite direction is referred to as "downward." Furthermore, with regard to the battery pack 2, the direction in which the battery pack 2 is slid when attached to the power tool 200 or the charger 300 is referred to as the rearward direction, and the direction in which the battery pack 2 is slid when removed from the power tool 200 or the charger 300 is referred to as the forward direction. That is, in the following description, the forward and backward directions correspond to the sliding directions in which the battery pack 2 is slid relative to the power tool 200 or the charger 300.

[0020] As shown in FIGS. 1 to 13B, the battery pack 2 includes a battery module 10 (see FIG. 9) and an outer case 12 (see FIG. 1) that houses the battery module 10. The outer case 12 is formed in a generally rectangular parallelepiped shape overall, and is divided into an upper case 14 and a lower case 15. As shown in FIG. 2, the upper case 14 and the lower case 15 are fixed to each other with four screws 18.

[0021] (Configuration of upper case 14) As shown in FIG. 1A, the upper case 14 is formed with a slide rail 20, a terminal receiving portion 22, a hook 24, and a ventilation hole 26.

[0022] The slide rail 20 extends in the front-to-rear direction and is disposed at the left and right ends of the upper portion of the upper case 14. As shown in FIG. 1A, the slide rail 20 includes a base 20a, an upward extension 20b, a first right extension 20c, and a second right extension 20d. As shown in FIG. 4C, the upward extension 20b extends upward from the left end of the base 20a. The first right extension 20c extends right from the upward extension 20b. The lower end of the first right extension 20c is located above the upper end of the base 20a. The right end of the first right extension 20c is located leftward of the right end of the base 20a. The second right extension 20d extends rightward from the upward extension 20b. The right end of the second right extension 20d coincides with the right end of the first right extension 20c in the left-right direction. As shown in FIG. 1A, the second right extension 20d is connected to the base 20a. The first right extension 20c and the second right extension 20d are provided with a plurality of recesses 20e aligned in the front-to-rear direction. The slide rail 20 slidably engages with the slide rail (not shown) of the power tool 200 and the slide rail 302 of the charger 300 (see FIG. 25B) when the battery pack 2 is attached to or detached from the power tool 200 or the charger 300. Specifically, the slide rail (not shown) of the power tool 200 and the slide rail 302 of the charger 300 slide between the base 20a and the first right extension 20c.

[0023] The terminal receiving portion 22 has four terminal openings 22a to 22d provided on the front upper surface 14b1 of the upper case 14. The terminal openings 22a to 22d are disposed between the left and right slide rails 20 and receive terminals 208a, 208b, 210a, and 210c (see FIG. 24B) of the power tool 200 and terminals (not shown) of the charger 300 when the battery pack 2 is attached to the power tool 200 or the charger 300. The terminal openings 22a to 22d are provided in the following order from the right slide rail 20 to the left slide rail 20: terminal opening 22a, terminal opening 22b, terminal opening 22c, and terminal opening 22d. As shown in FIGS. 1C, 12B, and 24B, battery-side recesses 23a to 23d are provided to surround the terminal openings 22a to 22d. The terminal openings 22a to 22d and the battery-side recesses 23a to 23d have a U-shape when viewed from above the battery pack 2. The battery-side recesses 23a to 23d are provided slightly below the front upper surface 14b1 of the outer case 12. In other words, the front upper surface 14b1 and the battery-side recesses 23a to 23d have a stepped shape.

[0024] The hook 24 is disposed at the upper front portion of the upper case 14. The hook 24 is a resin member and includes an operating portion 24a and a protruding portion 24b. The operating portion 24a is provided on the front surface 14a of the upper case 14. The hook 24 is held by the upper case 14 so as to be movable up and down. The hook 24 is biased upward by a compression spring (not shown), and moves downward when the operating portion 24a or the protruding portion 24b is pressed downward. When the battery pack 2 is attached to the power tool 200 or the charger 300, the protruding portion 24b engages with the housing (not shown) of the power tool 200 or the housing 304 of the charger 300 (see FIG. 25B ), thereby securing the battery pack 2 to the power tool 200 or the charger 300. When the battery pack 2 is to be removed from the power tool 200 or the charger 300, the user presses the operating portion 24a downward, causing the protruding portion 24b to move downward. In this state, the battery pack 2 can be slid to remove it from the power tool 200 or the charger 300. The operation unit 24a has a recessed shape on the inside. Therefore, when a user places a finger on the operation unit 24a and presses it downward, the finger can be pressed down without slipping.

[0025] The ventilation hole 26 is located rearward of the slide rail 20. The ventilation hole 26 is located at the rear of the rear upper surface 14b2 of the outer case 12. The rear upper surface 14b2 is located lower than the front upper surface 14b1 and higher than the base 20a of the slide rail 20. A battery-side recess 27 is provided on a portion of the right side, a portion of the left side, and in front of the ventilation hole 26. The battery-side recess 27 is located slightly lower than the rear upper surface 14b2. That is, the rear upper surface 14b2 and the battery-side recess 27 have a stepped shape. The charger 300 is provided with a charger-side protrusion 306 (see FIG. 25B ) that has a shape corresponding to the battery-side recess 27. Therefore, when the battery pack 2 is attached to the charger 300, the charger-side protrusion 306 is inserted into the battery-side recess 27.

[0026] As shown in FIG. 4A, the upper case 14 is provided with four screw holes 28 and five first protrusion portions 30a to 30e. Screws 18 (see FIG. 2) are screwed into the four screw holes 28. As shown in FIG. 4B, the first protrusion portions 30a to 30e protrude downward (i.e., toward the cell case 80 side) from the upper surface of the upper case 14. As shown in FIG. 4C, the first protrusion portion 30d is provided below the slide rail 20 (specifically, the base portion 20a), that is, inside the upper case 14. The first protrusion portions 30a to 30c and 30e are also provided below the slide rail 20. As shown in FIG. 5, the first protrusion portion 30 is composed of a thick portion 32a and a thin portion 32b. The thickness of the thick portion 32a in the left-right direction is larger than the thickness of the thin portion 32b in the left-right direction. In the first protrusion portion 30, the thick portion 32a and the thin portion 32b are alternately formed. As shown in FIG. 4A, the first protrusion portions 30a to 30d are composed of four thick portions 32a and three thin portions 32b. The first protrusion portion 30e is composed of three thick portions 32a and two thin portions 32b. As shown in FIG. 5, the length L1 of the first protrusion portions 30a to 30d in the front-rear direction is longer than the length L2 of the first protrusion portion 30e in the front-rear direction.

[0027] As shown in FIG. 4A, the upper case 14 is provided with six second protrusion portions 34a to 34f for aligning the upper case 14 and the lower case 15.

[0028] (Configuration of the lower case 15) As shown in FIGS. 1B and 8, the lower case 15 is composed of a front surface 15a, a right side surface 15b, a rear surface 15c, a left side surface 15d, and a bottom surface 15e. The front surface 15a is composed of a first upwardly extending surface 17a extending perpendicularly to the bottom surface 15e, an inclined surface 17b inclined relative to the bottom surface 15e, and a second upwardly extending surface 17c extending perpendicularly to the bottom surface 15e. As shown in FIG. 13B, the inclined surface 17b is inclined downward toward the rear. As shown in FIG. 1A, the lower case 15 is provided with an air vent 40 and a display unit 42. The display unit 42 is provided on the front surface 15a of the lower case 15. The display unit 42 includes a remaining charge display unit 42a that displays the remaining charge of the battery pack 2 to the user and a button 42b that switches the remaining charge display on and off. 1B, sloping surface 17b of lower case 15 is provided with ventilation holes 58a to 58d. Furthermore, bottom surface 15e of lower case 15 is provided with a hook 19. Hook 19 is used when removing battery pack 2 from power tool 200 or charger 300. Specifically, the user hooks hook 19 with the index finger or middle finger and presses operating unit 24a (see FIG. 1A) downward with the thumb.

[0029] As shown in FIG. 3, the ventilation hole 40 is provided in the lower part of the right side surface 15b of the lower case 15. The ventilation hole 40 is composed of ten holes 40a to 40j. The ten holes 40a to 40j are arranged in two rows, one above the other. Of the five holes 40a to 40e provided in the lower row, the rearmost hole 40a and the frontmost hole 40e have shorter front-to-rear lengths than the holes 40b to 44d. Furthermore, of the five holes 40f to 44j provided in the upper row, the rearmost hole 40f and the frontmost hole 40j have shorter front-to-rear lengths than the holes 40g to 44i. Furthermore, as shown in FIG. 8, a ventilation hole 41 similar to the ventilation hole 40 is also provided in the lower part of the left side surface 15d of the lower case 15. The ventilation hole 41 is composed of ten holes 41a to 41j.

[0030] Also, as shown in FIG. 6, the lower case 15 is provided with four screw holes 46, five front ribs 48, 50, 52, 54, 56, four vent holes 58a to 58d, eight side ribs 60a to 60h, four screw holes 62, and six second recessed portions 64a to 64f. The four screw holes 46 are provided at positions corresponding to the four screw holes 28 (see FIG. 4A) of the upper case 14. The four screw holes 62 are screw holes for fixing the lower case 15 and the battery module 10. The second recessed portions 64a to 64f are provided at positions corresponding to the second protruding portions 34a to 34f (see FIG. 4A) of the upper case 14, respectively. The bottom surface 15e of the lower case 15 is composed of a flat portion 16a, a protruding portion 16b, a recessed portion 16c, and a stepped portion 16d. The protruding portion 16b protrudes upward from the flat portion 16a. As shown in FIG. 18, the protruding portion 16b has a shape along the lower surface of the cell case 80 described later. As shown in FIG. 6, the recessed portion 16c is provided at the corner portions 15f at the four corners of the bottom surface 15e of the lower case 15. As shown in FIG. 19, the stepped portion 16d connects the flat portion 16a and the recessed portion 16c. The stepped portion 16d slopes downward from the inside to the outside of the lower case 15. The thickness t1 of the lower case 15 in the flat portion 16a is the same as the thickness t1 of the lower case 15 in the recessed portion 16c.

[0031] As shown in FIG. 7, the front ribs 48, 50, 52, 54, 56 are provided on the inclined surface 17b. The front ribs 48, 50, 52, 54, 56 extend upward from the inclined surface 17b and extend rearward from the front surface 15a of the lower case 15. The rear end of the front rib 48 substantially coincides with the rear end of the inclined surface 17b, and the upper end of the front rib 48 substantially coincides with the uppermost end of the inclined surface 17b. The upper surface of the front rib 48 is a flat surface. The rear end of the front rib 50 substantially coincides with the rear end of the inclined surface 17b, and the upper end of the front rib 50 is located above the upper end of the remaining amount display portion 42a. Further, a groove portion 50a is provided in the front rib 50. An LED substrate 84 (see FIG. 13A) described later passes through the groove portion 50a. The rear ends of the front ribs 52, 54 are located in front of the rear end of the inclined surface 17b. Further, the upper ends of the front ribs 52, 54 are located above the upper end of the remaining amount display portion 42a. The front rib 56 is composed of a light shielding wall portion 56a and a flat portion 56b. The light shielding wall portion 56a has the same structure as the front ribs 52, 54. The flat portion 56b has the same structure as the front rib 48.

[0032] The space above the inclined surface 17b is divided into four spaces S1 to S4 by the front ribs 48, 50, 56. Specifically, the first space S1 is defined by the front rib 48, the second space S2 is defined by the front ribs 48, 50, the third space S3 is defined by the front ribs 50, 56, and the fourth space S4 is defined by the front rib 56. Vent holes 58a to 58d are provided in each of the spaces S1 to S4. The vent holes 58a to 58d penetrate the lower case 15 in the vertical direction. Therefore, among the water that has entered the outer case 12, the water that has flowed into the spaces S1 to S4 is drained from the vent holes 58a to 58d.

[0033] As shown in FIG. 6, the side ribs 60a to 60d extend leftward from the right side surface 15b of the lower case 15. As shown in FIG. 8, the lower ends of the side ribs 60a to 60d extend upward from the bottom surface 15e of the lower case 15. The upper ends of the side ribs 60a to 60d are located slightly lower than the upper end of the lower case 15. The side ribs 60a to 60d are provided between adjacent holes 40 in the front-to-rear direction. Specifically, the side rib 60a is provided between the holes 40a, 40f and the holes 40b, 40g, the side rib 60b is provided between the holes 40b, 40g and the holes 40c, 40h, the side rib 60c is provided between the holes 40c, 40h and the holes 40d, 40i, and the side rib 60d is provided between the holes 40d, 40i and the holes 40e, 40j. The side ribs 60e to 60h have the same structure as the side ribs 60e to 60h, except that they extend rightward from the left side surface 15d of the lower case 15.

[0034] (Configuration of battery module 10) As shown in FIG. 9A, the battery module 10 includes a cell case 80, a control board 82, and an LED board 84. The cell case 80 is made of an insulating material, such as a resin material. As shown in FIG. 11A, the cell case 80 is divided into a right cell case 85 and a left cell case 86. A vent hole 81a is provided in the front portion 80a of the cell case 80, and a vent hole 81b is provided in the rear portion 80b of the cell case 80. Thickened portions 80c are provided at the four corners of the lower portion of the cell case 80. As shown in FIG. 19, the thickness t11 of the thickened portions 80c is greater than the thickness t12 of a cell holding portion 87, which will be described later. As shown in FIG. 11A, the top surface 80d of the cell case 80 has a shape corresponding to the longitudinal side surface of a battery cell 90 (see FIG. 10), which will be described later. A recessed portion 80g is provided between two adjacent battery cells 90 on the top surface 80d of the cell case 80. The top surface 80d of the cell case 80 is provided with four screw bosses 83 used to connect the control board 82 and the cell case 80. As shown in FIG. 9B, protrusions 116a to 116c that protrude upward from the top surface 80d of the cell case 80 are provided at the top of the left side surface 80f of the cell case 80. As shown in FIG. 11C, the protrusions 116a to 116c are arranged so as to straddle two adjacent battery cells 90. First recesses 110a to 110c are provided in the protrusions 116a to 116c. The first recesses 110a to 110c are provided at positions corresponding to the first protrusions 30a to 30c (see FIG. 4A) of the upper case 14. As shown in FIG. 9A, protrusions 116d and 116e that protrude upward from the top surface 80d of the cell case 80 are provided at the top of the right side surface 80e of the cell case 80. 11C, protrusions 116d, 116e are arranged so as to straddle two adjacent battery cells 90. First recesses 110d, 110e are provided in protrusions 116d, 116e. The first recesses 110d, 110e are provided at positions corresponding to first protrusions 30d, 30e (see FIG. 4A) of the upper case 14, respectively. As shown in FIG. 11C, protrusions 116a-116e and first recesses 110a-110e are provided outside of the control board 82 when the battery module 10 is viewed from above.The first recessed portions 110a to 110e are provided between two lead plates 92 described later. As shown in FIG. 9A, the protruding portion 116d and the first recessed portion 110d are provided between the lead plates 92c and 92d, and the protruding portion 116e and the first recessed portion 110e are provided between the lead plates 92d and 92e. Also, as shown in FIG. 9B, the protruding portion 116a and the first recessed portion 110a are provided between the lead plates 92j and 92k, the protruding portion 116b and the first recessed portion 110b are provided between the lead plates 92i and 92j, and the protruding portion 116c and the first recessed portion 110c are provided between the lead plates 92h and 92i.

[0035] As shown in FIG. 11B, the right cell case 85 is provided with ten cell holding portions 87a to 87j. The ten cell holding portions 87a to 87j are arranged in two upper and lower rows. As shown in FIG. 18, which is a cross-sectional view of the battery pack 2 at the center position in the left-right direction, the cell holding portions 87a to 87c have a central-side holding portion 89a that holds the central side of a battery cell 90 described later. Also, as shown in FIG. 19, which is a cross-sectional view of the battery pack 2 at the position where the recessed portion 16c is provided at the rear right side of the lower case 15, the cell holding portions 87a to 87c have an end-face-side holding portion 89b that holds the right end-face side in the longitudinal direction of the battery cell 90. Although not shown, the cell holding portions 87d and 87e also have a central-side holding portion and an end-face-side holding portion. As shown in FIG. 11B, between the cell holding portions 87a, 87b, 87f, 87g and between the cell holding portions 87d, 87e, 87i, 87j, connecting portions 88 for connecting the right cell case 85 and the left cell case 86 are provided. Although not shown, the left cell case 86 is provided with ten cell holding portions corresponding to the ten cell holding portions 87a to 87j of the right cell case 85 and two connecting portions corresponding to the two connecting portions 88 of the right cell case 85.

[0036] As shown in FIG. 10, ten battery cells 90a to 90j are arranged side by side in two upper and lower rows in the cell case 80. The battery cell 90 is a cylindrical secondary battery cell, for example, a lithium ion battery cell, with a positive electrode formed at one end and a negative electrode formed at the other end. In this embodiment, the battery cell 90 is an 18650-type lithium ion battery cell, and the rated voltage is 3.6 [V]. The battery cells 90 are arranged such that the directions from the positive electrode to the negative electrode are opposite to each other in the battery cells 90 adjacent in the vertical direction. In the lower row of battery cells 90a to 90e, the rearmost battery cell 90a is arranged such that the right end face side is the negative electrode and the left end face side is the positive electrode. Also, the battery cells 90b to 90e are arranged such that the right end face side is the positive electrode and the left end face side is the negative electrode. In the upper row of battery cells 90f to 90j, the rearmost battery cell 90f is arranged such that the right end face side is the positive electrode and the left end face side is the negative electrode. Also, the battery cells 90g to 90j are arranged such that the right end face side is the negative electrode and the left end face side is the positive electrode. The metal part 91 (see FIG. 20 for example) constituting the positive electrode of each battery cell 90 and the metal part constituting the negative electrode are connected to the end face of the battery cell 90. One end of the battery cell 90 is connected via a metal part to the metal lead plates 92a to 92f provided on the right side face 80e side of the cell case 80 (see FIG. 9A), and the other end of the battery cell 90 is connected via a metal part to the metal lead plates 92g to 92k provided on the left side face 80f side of the cell case 80 (see FIG. 9B). As shown in FIG. 20, a waterproof ring 95 is provided on the metal part 91 constituting the positive electrode of the battery cell 90. In FIGS. 9A and 9B, the portion where a thick-lined circle is drawn on the surface of the lead plate 92 indicates that the waterproof ring 95 is arranged inside. Therefore, the positive electrode of the battery cell 90 is connected to the portion where a thick-lined circle is drawn on the surface of the lead plate 92.

[0037] As shown in FIG. 9A, the lead plates 92a-92f are arranged at intervals from one another. Therefore, the lead plates 92a-92f are insulated from one another. The lead plate 92a is connected only to the positive electrode of battery cell 90f. The lead plate 92f is connected only to the negative electrode of battery cell 90j. The lead plate 92b connects two adjacent battery cells 90a and 90b in the front-to-rear direction. The lead plates 92c-92e connect two adjacent battery cells 90a and 90b in the diagonal direction. Specifically, the lead plate 92c is connected to the negative electrode of battery cell 90g and the positive electrode of battery cell 90c. The lead plate 92d is connected to the negative electrode of battery cell 90h and the positive electrode of battery cell 90d. The lead plate 92e is connected to the negative electrode of battery cell 90i and the positive electrode of battery cell 90e.

[0038] 9B, the lead plates 92g-92k are spaced apart from one another. Therefore, the lead plates 92g-92k are insulated from one another. The lead plates 92g-92k connect adjacent battery cells 90 in the vertical direction. Specifically, lead plate 92g connects the negative electrode of battery cell 90e to the positive electrode of battery cell 90j. Lead plate 92h connects the negative electrode of battery cell 90d to the positive electrode of battery cell 90i. Lead plate 92i connects the negative electrode of battery cell 90c to the positive electrode of battery cell 90h. Lead plate 92j connects the negative electrode of battery cell 90b to the positive electrode of battery cell 90g. Lead plate 92k connects the positive electrode of battery cell 90a to the negative electrode of battery cell 90f. With the above configuration, the ten battery cells 90 are electrically connected in series. Therefore, the rated voltage of the battery pack 2 is 36 V. Although not shown, insulating sheets are attached to the right side surface 80e and the left side surface 80f of the cell case 80.

[0039] According to the above configuration, the lead plates 92a and 92f connected to the control board 82 via a power line (not shown) can be connected to the upper battery cells 90f and 90j. A larger current flows through the lead plates 92a and 92f connected to the control board 82 than through the other lead plates. Therefore, it is desirable that the widths of the lead plates 92a and 92f be large. According to the above configuration, sufficient widths of the lead plates 92a and 92f can be ensured. Also, if at least one of the lead plates 92a and 92f connected to the control board 82 is connected to the lower battery cell, it is necessary to route the power line from the lower part of the cell case 60. Since the clearance between the lower part of the cell case 60 and the right side surface of the outer case 12 is small, it is difficult to route the power line. According to the above configuration, since both of the lead plates 92a and 92f connected to the control board 82 are connected to the upper battery cells 90f and 90j, the power line connecting the lead plates 92a and 92f and the control board 82 can be easily routed. Also, compared with the case where at least one of the lead plates 92a and 92f is connected to the lower-stage battery cell 90, the length of the current line connecting the lead plates 92a and 92f and the control board 82 can be shortened, so that the resistance due to the power line connecting the lead plates 92a and 92f and the control board 82 can be reduced.

[0040] As shown in FIG. 10, in a state where the cell case 80 holds ten battery cells 90a to 90j, the upper-stage battery cells 90f to 90j and the lower-stage battery cells 90a to 90e are arranged at intervals in the vertical direction. Also, clearances are provided between the battery cells 90a, 90b, 90f, 90g and the rear connecting portion 88, and between the battery cells 90d, 90e, 90i, 90j and the front connecting portion 88. For this reason, the air flowing into the cell case 80 from the vent hole 81a or the vent hole 81b of the cell case 80 can pass between the upper-stage battery cells 90f to 90j and the lower-stage battery cells 90a to 90e, between the battery cells 90a, 90b, 90f, 90g and the rear connecting portion 88, and between the battery cells 90d, 90e, 90i, 90j and the front connecting portion 88.

[0041] 9A, the control board 82 is disposed above the cell case 80. The control board 82 is disposed along a plane perpendicular to the up-down direction. The control board 82 is fixed to the cell case 80 via fasteners 100.

[0042] A plurality of terminals 102 are provided on the upper surface of the control board 82. The plurality of terminals 102 include a battery-side negative terminal 104a used for discharging or charging when the battery pack 2 is attached to the power tool 200 or the charger 300, a battery-side positive terminal 104b used for discharging or charging, and a plurality of battery-side signal terminals 106a to 106d used for transmitting and receiving signals. The battery-side negative terminal 104a and the battery-side positive terminal 104b are provided outside the battery-side signal terminals 106a to 106d in the left-right direction. The battery-side negative terminal 104a is provided on the right side of the control board 82, and the battery-side positive terminal 104b is provided on the left side of the control board 82. The battery-side signal terminals 106a and 106b are provided side by side in the front and rear. The battery-side signal terminals 106c and 106d are provided side by side in the front and rear. As shown in FIG. 12B, the battery-side negative terminal 104a is positioned at a position corresponding to the terminal opening 22a of the upper case 14, the battery-side signal terminals 106a and 106b are positioned at a position corresponding to the terminal opening 22b, the battery-side signal terminals 106c and 106d are positioned at a position corresponding to the terminal opening 22c, and the battery-side positive terminal 104b is positioned at a position corresponding to the terminal opening 22d.

[0043] 9A and 9B, the cell case 80 is provided with four fixing portions 112. Each fixing portion 112 is provided at a position corresponding to a screw hole 62 of the lower case 15. As shown in FIG. 12A, the lower case 15 and the battery module 10 are fixed to each other with four screws 114.

[0044] As shown in FIG. 9A, the LED board 84 is connected to the control board 82 via a signal line 120. The LED board 84 includes four LEDs 84a and a switch 84b. As shown in FIG. 13A, when the battery module 10 and the lower case 15 are fixed together, the LED board 84 is disposed near the rear surface of the display unit 42 of the lower case 15. Specifically, the LEDs 84a are disposed on the rear surface of the remaining battery level display unit 42a, and the switch 84b is disposed on the rear surface of the button 42b. That is, the LED board 84 faces the front surface 14a inside the lower case 15. The LED board 84 is inserted into the groove 50a of the front rib 50 of the lower case 15 and rests on the front ribs 48 and 56. Therefore, the LED board 84 is held by the lower case 15. The front surface of the LED board 84 contacts the rear ends of the front ribs 52 and 54 and the light-shielding wall portion 56a of the front rib 56. Moreover, the LED substrate 84 has ventilation holes 58a to 58d formed on the surface opposite to the lower surface 84c.

[0045] Below, with reference to Figures 14 to 17, we will explain the engagement clearance C1 between the first protrusion portion 30 of the upper case 14 and the first recess portion 110 of the battery module 10, and the engagement clearance C2 between the second protrusion portion 34 of the upper case 14 and the second recess portion 64 of the lower case 15.

[0046] As shown in Fig. 14, the first protrusions 30a to 30e of the upper case 14 are respectively received in the first recesses 110a to 110e of the battery module 10. As shown in Fig. 15, an engagement clearance C1 is provided between the first protrusion 30d and the first recess 110d.

[0047] Also, as shown in FIG. 16, each of the second rib portions 34a to 34f of the upper case 14 is received in each of the second recess portions 64a to 64f of the lower case 15. As shown in FIG. 17, an engagement clearance C2 is provided between the second rib portion 34e and the second recess portion 64e. The engagement clearance C2 is used for positioning the upper case 14 and the lower case 15. The engagement clearance C1 in FIG. 14 is used for suppressing the displacement between the upper case 14 and the cell case 80. The engagement clearance C1 may be set so as to suppress the displacement between the upper case 14 and the cell case 80 and prevent the upper case 14 from contacting the control board 82. For this reason, the engagement clearance C1 is larger than the engagement clearance C2. As shown in FIG. 16, a labyrinth structure is formed by the second rib portions 34a to 34f and the second recess portions 64a to 64f. Thereby, the intrusion of water into the outer case 12 is suppressed.

[0048] Subsequently, with reference to FIGS. 18 and 19, the case clearances C11 to C13 between the lower surface of the cell case 80 of the battery module 10 and the lower case 15 will be described. As described above, FIG. 18 shows a cross-sectional view of the battery pack 2 at the central position in the left-right direction, and FIG. 19 shows a cross-sectional view of the battery pack 2 at the position where the recess 16c on the right rear side of the lower case 15 is provided.

[0049] As shown in FIG. 18, the lower surface of the cell case 80 does not contact the bottom surface 15e of the lower case 15. Specifically, a case clearance C11 is provided between the central holding portion 89a of the cell holding portions 87a to 87c and the protruding portion 16b protruding upward (i.e., inward) from the bottom surface 15e of the lower case 15. Also, a case clearance C12 is provided between the central holding portion 89a and the flat portion 16a. The case clearance C12 is larger than the case clearance C11.

[0050] Also, as shown in FIG. 19, a case clearance C13 is provided between the end face side holding portion 89b corresponding to the battery cell 90a disposed at the position closest to the corner portion 15f of the lower case 15 and the recessed portion 16c. Among the bottom face 15e of the lower case 15, a step portion 16d is provided between the face facing the side face 93a of the battery cell 90a and the face facing the side face 93b of the battery cell 90b. Note that, among the bottom face 15e of the lower case 15, the step portion 16d is not provided between the face facing the side face 93b of the battery cell 90b and the face facing the side face 93c of the battery cell 90c. For this reason, the case clearance C13 is larger than the case clearance C12.

[0051] Subsequently, with reference to FIG. 20, the positional relationship between the battery cell 90c located at the center of the lower row among the plurality of battery cells 90 and the holes 40c and 40h provided to the right of the battery cell 90c will be described. Note that, in FIG. 20, the lead plate 92i is omitted for easy understanding.

[0052] As shown in FIG. 20, on the right side face 15b, the holes 40c and 40h are provided at positions facing the longitudinal end faces of the battery cell 90c. Note that, on the right side face 15b, no hole is provided at a position facing the longitudinal end face of the battery cell 90h located above the battery cell 90c. A part of the holes 40c and 40h faces the longitudinal end face of the battery cell 90h.

[0053] The metal portion 91 constituting the positive electrode of the battery cell 90c is provided on the right end face of the battery cell 90c. The lower end 43h of the upper hole 40h and the lower end 43c of the lower hole 40c are provided below the upper end 94a of the battery cell 90c and below the longitudinal axis A1 of the battery cell 90c. Also, the lower end 43c of the lower hole 40c is provided below the lower end 91a of the metal portion 91 and below the lower end 94b of the battery cell 90c.

[0054] Next, referring to FIG. 21, the air flow within the battery pack 2 will be described. For example, assume a situation where the battery pack 2 is attached to the power tool 200, the power tool 200 is used by the user, and the battery pack 2 is removed from the power tool 200. In this case, the battery pack 2 is at a high temperature. In such a situation, the ventilation holes 40 and 41 provided at the lower part of the lower case 15 shown in FIGS. 1A, 3, and 8 function as intake holes through which air is introduced from the outside to the inside of the battery pack 2. Specifically, the air around the battery pack 2 is heated, and the air around the battery pack 2 flows into the battery pack 2 through the ventilation holes 40 and 41. The air introduced into the battery pack 2 from the ventilation hole 40 flows into the space between the plurality of battery cells 90 and the lower case 15. As described above, side ribs 60a to 60d are provided between each of the holes 40a to 40j. Therefore, as shown in FIG. 20, the air introduced from the holes 40c and 40h flows into the space between the battery cells 90c and 90h and the right side surface 15b of the lower case 15. Similarly, the air introduced from the holes 40a and 40f flows into the space between the battery cells 90b and 90g and the right side surface 15b of the lower case 15, the air introduced from the holes 40b and 40g flows into the space between the battery cells 90b and 90g and the right side surface 15b of the lower case 15, the air introduced from the holes 40d and 40i flows into the space between the battery cells 90d and 90i and the right side surface 15b of the lower case 15, and the air introduced from the holes 40e and 40j flows into the space between the battery cells 90e and 90j and the right side surface 15b of the lower case 15. Accordingly, the plurality of battery cells 90 are reliably cooled. The air that has flowed into the space between the plurality of battery cells 90 and the right side surface 15b of the lower case 15 flows out of the battery pack 2 through the terminal opening 22a of the terminal receiving portion 22 of the upper case 14 and the like after cooling the plurality of battery cells 90. Thus, in a situation where the battery pack 2 is at a high temperature, natural convection occurs. Note that the air introduced into the battery pack 2 from the ventilation hole 41 also flows into the space between each battery cell 90 and the left side surface 15d of the lower case 15 and is used for cooling the battery cells 90.

[0055] 22 and 23, the air flow inside the battery pack 2 when the battery pack 2 is attached to the charger 300 will be described. The charger 300 is equipped with a blower fan (not shown) that is configured to draw air from the battery pack 2. In this state, the air vents 40 (see FIG. 1), 58a to 58d (see FIG. 6) of the battery pack 2 function as intake holes that introduce air from the outside to the inside of the battery pack 2, and the air vent 26 (see FIG. 1) of the battery pack 2 functions as an exhaust hole that exhausts air from the inside of the battery pack 2 to the charger 300.

[0056] As shown in FIG. 22, when the blower fan of the charger 300 is driven, the air introduced into the battery pack 2 from the ventilation hole 58 (see FIG. 1B) flows into the space between the front portion 80a of the cell case 80 and the front surface 15a of the lower case 15. An LED substrate 84 is provided between the front portion 80a of the cell case 80 and the front surface 15a of the lower case 15. The air flowing into the space between the front portion 80a of the cell case 80 and the front surface 15a of the lower case 15 flows into the cell case 80 through the space between the front portion 80a of the cell case 80 and the LED substrate 84 and through the ventilation hole 81a of the cell case 80. The air introduced into the cell case 80 passes between the upper battery cells 90f to 90j and the lower battery cells 90a to 90e, between the battery cells 90a, 90b, 90f, 90g and the rear connecting portion 88, and between the battery cells 90d, 90e, 90i, 90j and the front connecting portion 88. The air passing through the cell case 80 cools the plurality of battery cells 90. Then, the air that has cooled the plurality of battery cells 90 is introduced into the charger 300 through the ventilation hole 81b in the rear portion 80b of the cell case 80, the ventilation hole 26 in the upper case 14, and the ventilation hole 308 (see FIG. 25B) of the charger 300 corresponding to the ventilation hole 26. As described above, in a state where the battery pack 2 is attached to the charger 300, the charger-side protrusion 306 of the charger 300 is inserted into the battery-side bulge portion 27 around the ventilation hole 26. Therefore, the amount of air sucked into the charger 300 from the gap between the battery pack 2 and the charger 300 can be reduced as compared with the case where the battery-side bulge portion 27 is not provided around the ventilation hole 26. Thereby, the amount of air flowing through the battery pack 2 can be increased. Therefore, the battery cells 90 and the lead plate 92 in the battery pack 2 can be efficiently cooled.

[0057] Also, as shown in FIG. 23, the air introduced into the battery pack 2 from the vent holes 40 flows into the space between the plurality of battery cells 90 (specifically, the lead plates 92) and the right side surface 15b of the lower case 15. The air that has flowed into the space between the battery cells 90 and the right side surface 15b of the lower case 15 flows forward above the plurality of side ribs 60a to 60d and into the space between the front portion 80a of the cell case 80 and the front surface 15a of the lower case 15. The subsequent air flow is the same as in the case of FIG. 22. In this way, the air introduced from the vent holes 58 and 40 is used to cool the plurality of battery cells 90. In this embodiment, since the vent holes 40 are provided in the lower part of the lower case 15, in the state where the battery pack 2 is attached to the charger 300, the vent holes 40 are located at a position higher than the charger 300. Since dust and the like accumulate at positions with a lower height, in the state where the battery pack 2 is attached to the charger 300, it is difficult to suck in dust and the like.

[0058] The effect of the battery-side recesses 23a-23d of the upper case 14 of the battery pack 2 will be described with reference to Fig. 24B. Fig. 24B is a cross-sectional view of the battery-side signal terminal 106a (see Fig. 12A) of the battery pack 2 at the center in the front-rear direction when the battery pack 2 is attached to the power tool 200. As shown in Fig. 24B, the power tool 200 includes a terminal holder 202, which is provided with tool-side protrusions 206a-206d that protrude downward (i.e., toward the battery pack 2). The tool-side protrusion 206a is provided with a tool-side negative terminal 208a corresponding to the battery-side negative terminal 104a, and the tool-side protrusion 206d is provided with a tool-side positive terminal 208b corresponding to the battery-side positive terminal 104b. The tool-side protrusion 206b is provided with a tool-side signal terminal 210a corresponding to the battery-side signal terminal 106a. A tool-side signal terminal (not shown) corresponding to the battery-side signal terminal 106b is provided on the tool-side protrusion 206b in front of the tool-side signal terminal 210a. The tool-side protrusion 206c is provided with a tool-side signal terminal 210c corresponding to the battery-side signal terminal 106c. The battery-side signal terminal 106d is a terminal that is used only when the battery pack 2 is attached to the charger 300, so no tool-side signal terminal corresponding to the battery-side signal terminal 106d is provided on the tool-side protrusion 206c in front of the tool-side signal terminal 208c. When the battery pack 2 is attached to the power tool 200, the tool-side protrusions 206a to 206d are inserted into the battery-side recesses 23a to 23d, respectively. With this configuration, the creepage distance between two adjacent terminals in the left-right direction among the multiple terminals of the power tool 200 can be increased compared to when the tool-side protrusions 206a-206d are not provided on the terminal holder 202 of the power tool 200. Specifically, the creepage distance can be increased by the height of the tool-side protrusions 206a-206d. Therefore, it is possible to prevent a short circuit between two adjacent terminals in the left-right direction among the multiple terminals of the power tool 200.

[0059] In one or more embodiments, as shown in FIGS. 1 to 13 , a battery pack 2 includes an upper case 14, an outer case 12 including a lower case 16 fixed to the upper case 14, battery cells 90, and a cell case 80 that houses the battery cells 90. Also, as shown in FIGS. 18 and 19 , case clearances C11 to C13 are provided between the entire lower surface of the lower case 16 and the cell case 80. With this configuration, even if an impact is applied to the lower case 16 of the outer case 12 and the lower case 16 is deformed, the lower case 16 can be prevented from coming into contact with the underside of the cell case 80. Therefore, when an impact is applied to the lower case 16, deformation of the battery cells 90 housed in the cell case 80 can be prevented.

[0060] 12A, the cell case 80 is screwed to the lower case 16. With the above configuration, it is possible to prevent misalignment between the lower case 15 and the cell case 80, for example, when a user drops the battery pack 2. Therefore, it is possible to further prevent damage to the battery cells 90 housed in the cell case 80 when an impact is applied to the lower case 15.

[0061] In one or more embodiments, as shown in FIG. 10, five battery cells 90a to 90e are accommodated side by side in the lower case 15 in parallel to the bottom surface 15e of the lower case 15. The five battery cells 90a to 90e are composed of the battery cells 90a and 90e closest to the corner 15f of the lower case 15 and the battery cells 90b to 90d provided inside the battery cells 90a and 90e. As shown in FIG. 19, the case clearance C13 between the cell holder 87a holding the battery cell 90a and the lower case 16 is larger than the case clearance C12 between the cell holder 87b holding the battery cell 90b and the lower case 15. According to the above configuration, even when the corners 15f at the four corners of the bottom surface 15e of the lower case 15 are deformed, it is possible to suppress the lower case 15 from contacting the lower surface of the cell case 80. Therefore, when an impact is applied to the lower case 16, it is possible to further suppress the battery cells 90 accommodated in the cell case 80 from being damaged.

[0062] In one or more embodiments, as shown in FIGS. 18 and 19, the cell holder 87a holding the battery cell 90a is composed of an end face side holder 89b that holds the end face side in the longitudinal direction of the battery cell 90a and a central side holder 89a that holds the central side in the longitudinal direction of the battery cell 90a. The case clearance C13 between the end face side holder 89b and the lower case 15 is larger than the case clearance C12 between the central side holder 89a and the lower case 15. The end face side holder 89b is closer to the corners 15f at the four corners of the bottom surface 15e of the lower case 15 than the central side holder 89a. According to the above configuration, even when the corners 15f at the four corners of the bottom surface 15e of the lower case 15 are deformed, it is possible to suppress the lower case 15 from contacting the lower surface of the cell case 80. Therefore, when an impact is applied to the lower case 16, it is possible to further suppress the battery cells 90 accommodated in the cell case 80 from being damaged.

[0063] In one or more embodiments, as shown in FIGS. 6 and 19, a step portion 16d is provided between the bottom surface 15e of the lower case 15 where the side surface 93a of the battery cell 90a and the side surface 93b of the battery cell 90b face each other. The step portion slopes downward from the side of the battery cell 90b toward the side of the battery cell 90a. According to the above configuration, the case clearance C13 between the cell holding portion 87a that holds the battery cell 90a and the lower case 16 can be made larger than the case clearance C12 between the cell holding portion 87b that holds the battery cell 90b and the lower case 16. Therefore, even when the corner portions 15f at the four corners of the bottom surface 15e of the lower case 15 are deformed, it is possible to suppress the lower case 15 from contacting the lower surface of the cell case 80. Accordingly, when an impact is applied to the lower case 15, it is possible to further suppress the battery cell 90 housed in the cell case 80 from being damaged.

[0064] In one or more embodiments, as shown in FIG. 19, the thickness t11 of the thick portion 80c at the four corners at the lower part of the cell case 80 is thicker than the thickness t12 of the cell case 80 below the longitudinal axis A1 of the battery cell 90. According to the above configuration, the strength of the portion of the cell case 80 where the lower case 16 is likely to contact can be increased. Therefore, even when the lower case 16 contacts the cell case 80, it is possible to suppress the battery cell 90 housed in the cell case 80 from being damaged.

[0065] (Corresponding relationship) The battery cells 90a and 90e are examples of the "outer battery cells". The battery cells 90b to 90d are examples of the "inner battery cells". The cell holding portion 87a that holds the battery cell 90a and the cell holding portion 87b that holds the battery cell 90b are examples of the "first holding portion" and the "second holding portion", respectively.

[0066] (Second embodiment) Referring to FIG. 26, the battery pack 602 of the second embodiment will be described. The structure of the lower case 615 of the outer case 612 of the battery pack 602 of the second embodiment is different from the structure of the lower case 15 of the outer case 12 of the battery pack 2 of the first embodiment. Also, in the battery pack 602 of this embodiment, the size of the battery cells (not shown) housed in the outer case 612 is different from that of the battery cells 90 housed in the outer case 12 of the first embodiment. Specifically, the battery cells of this embodiment are 21700-type lithium-ion battery cells, and the rated voltage is 3.6 [V]. For this reason, the outer case 612 is larger in size than the outer case 12 of the first embodiment. Note that the fact that 10 battery cells are housed in the outer case 612 and the connection method of each battery cell are the same as those of the battery pack of the first embodiment. Therefore, the rated voltage of the battery pack 602 of this embodiment is also 36 [V].

[0067] As shown in FIG. 26, two hook portions 619a and 619b arranged in the front-rear direction are provided on the bottom surface 615e of the lower case 615. According to such a configuration, when the user removes the battery pack 2 from the power tool 200 or the charger 300, the user can use the hook portion 619 suitable for the length of the user's finger among the two hook portions 619a and 619b. Therefore, it is possible to make it easier to remove the battery pack 2 from the power tool 200 or the charger 300.

[0068] Further features of the battery pack disclosed by this specification are described below. (Feature 1) A battery pack that can be slid and attached to a power tool, a first terminal, a second terminal, and an outer case that houses the first terminal and the second terminal. On the upper surface of the outer case, a first terminal opening provided at a position corresponding to the first terminal and a second terminal opening provided at a position corresponding to the second terminal are provided. The battery pack has battery-side recesses between the first terminal opening and the top surface, and between the second terminal opening and the top surface. (Feature 2) 2. The battery pack according to claim 1, wherein the battery-side recess has a shape corresponding to a tool-side protrusion of the power tool. (Feature 3) the first terminal is a discharge terminal, 3. The battery pack according to claim 1, wherein the second terminal is a signal terminal. (Feature 4) A first terminal; A second terminal; A third terminal; The fourth terminal, an outer case that houses the first terminal, the second terminal, the third terminal, and the fourth terminal, The outer case includes a pair of slide rails for slidingly receiving the power tool. a first terminal opening provided at a position corresponding to a first terminal, a second terminal opening provided at a position corresponding to a second terminal, a third terminal opening provided at a position corresponding to a third terminal, and a fourth terminal opening provided at a position corresponding to a fourth terminal on an upper surface of the outer case between the pair of slide rails; the first terminal opening, the second terminal opening, the third terminal opening, and the fourth terminal opening are arranged in this order from one slide rail of the pair of slide rails to the other slide rail; a battery-side recess provided between the first terminal opening and the top surface, between the second terminal opening and the top surface, between the third terminal opening and the top surface, and between the fourth terminal opening and the top surface. (Feature 5) 5. The battery pack according to claim 4, wherein the battery-side recess has a shape corresponding to a tool-side protrusion of the power tool. (Feature 6) the first terminal and the fourth terminal are discharge terminals, The battery pack according to feature 4 or 5, wherein the second terminal and the third terminal are signal terminals. (Feature 7) A battery pack that can be slid from front to back and attached to an external device, comprising an outer case, wherein the outer case, has a pair of slide rails for sliding and receiving the external device, a terminal opening provided between the pair of slide rails, is between the pair of slide rails, and a surface behind the terminal opening, a ventilation hole, and a battery side bulging portion provided between the surface behind the terminal opening and the ventilation hole between the pair of slide rails. (Feature 8) The battery pack according to feature 7, wherein the battery side bulging portion has a shape corresponding to a device side protruding portion of the external device.

[0069] As described above, specific examples of the present invention have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

[0070] (First Modification Example) The cell case 80 may be screwed to the upper case 14.

[0071] (Second Modification Example) The case clearances C11 to C13 may be the same. Also, the case clearances C11 and C12 may be larger than the case clearance C13.

[0072] (Third Modification Example) The step portion 16d may not be provided on the bottom surface 15e of the lower case 15.

[0073] (Fourth Modification) The thick portions 80c do not have to be provided at the four corners of the lower part of the cell case 80. In other words, when the cell case 80 is viewed from the right, the four corners of the lower part of the cell case 80 may have a shape that corresponds to the outer shape of the battery cell 90.

[0074] The technical elements described in this specification or drawings may exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings may achieve multiple objectives simultaneously, and achieving one of those objectives alone is technically useful. [Explanation of symbols]

[0075] 2: Battery pack, 10: Battery module, 12: Outer case, 14: Upper case, 14a: Front surface, 14b1: Upper surface on the front side, 14b2: Upper surface on the rear side, 15: Lower case, 15a: Front surface, 15b: Right side surface, 15c: Rear surface, 15d: Left side surface, 15e: Bottom surface, 15f: Corner, 16a: Flat portion, 16b: Protrusion, 16c: Depression, 16d: Step portion, 17a: First upward extending surface, 17b: Inclined surface, 17c: Second upward extending surface, 18: Screw, 19: Hooking portion, 20: Slide rail, 20a: Base portion, 20b: Upward extending portion, 20c: First rightward extending portion, 20d: Second rightward extending portion, 20e: Depression, 22: Terminal receiving portion, 22a~22d: Terminal openings, 23a~23d: Battery side depressions, 24: Hook, 24a: Operating portion, 24b: Protrusion, 26: Vent hole, 27: Battery side depression, 28: Screw hole, 30a~30e: First rib portion, 32a: Thick portion, 32b: Thin portion, 34a~34f: Second rib portion, 40: Vent hole, 40a~40j: Holes, 41: Vent hole, 41a~41j: Holes, 42: Display portion, 42a: Remaining amount display portion, 42b: Button, 43c: Lower end, 43h: Lower end, 46: Screw hole, 48: Front rib, 50: Front rib, 50a: Groove portion, 52: Front rib, 54: Front rib, 56: Front rib, 56a: Light shielding wall portion, 56b: Flat portion, 58a~58d: Vent holes, 60a~60h: Side ribs, 62: Screw hole, 64a~64f: Second depression, 80: Cell case, 80a: Front portion, 80b: Rear portion, 80c: Thick portion, 80d: Upper surface, 80e: Right side surface, 80f: Left side surface, 80g: Depression, 81a: Vent hole, 81b: Vent hole, 82: Control board, 83: Screw boss, 84: LED board, 84a: LED, 84b: Switch, 84c: Lower surface, 85: Right cell case, 86: Left cell case, 87a~87j: Cell holding portions, 88: Connecting portion, 89a: Central side holding portion, 89b: End face side holding portion, 90a~90j: Battery cells, 91: Metal portion, 91a: Lower end, 92a~92k: Lead plates, 93a~93c: Side surfaces, 93b: Side surfaces, 93c: Side surfaces, 94: Waterproof ring, 94a: Upper end, 94b: Lower end, 100: Fastener, 102: Terminal, 104a: Battery side negative terminal, 104b: Battery side positive terminal, 106a~106d: Battery side signal terminals, 110a~110e: First depression, 112: Fixed portion, 114: Screw, 116a~116e: Protrusions, 120: Signal wire, 200: Power tool, 202: Terminal holding portion206a~206d: Tool-side rib portions, 208a: Tool-side negative terminal, 208b: Tool-side positive terminal, 210a, 210c: Tool-side signal terminals, 300: Charger, 302: Slide rail, 304: Housing, 306: Charger-side rib portion, 308: Vent hole, 602: Battery pack, 612: Outer case, 615: Lower case, 615e: Bottom surface, 619a, 619b: Hooking portions

Claims

1. A battery pack, comprising an outer case, wherein the outer case has an upper surface provided with a terminal opening for exposing a terminal, a bottom surface, and side surfaces extending upward from the bottom surface, wherein protruding portions protruding downward are provided at the four corners of the bottom surface, when the battery pack placed on a placement surface is viewed from the side surface side, only the protruding portions are placed on the placement surface, the four corners include a first corner provided on the bottom surface and the side surfaces, and a second corner provided on the bottom surface and the side surfaces and aligned with the first corner in a first direction, in the side surface, between the first corner and the second corner, a recessed portion recessed inside the outer case more than the first corner and the second corner is provided, and an opening is provided in the recessed portion, a battery pack.

2. A battery pack, comprising an outer case, wherein the outer case has an upper surface provided with a terminal opening for exposing a terminal, a bottom surface, and side surfaces extending upward from the bottom surface, wherein protruding portions protruding downward are provided at the four corners of the bottom surface, when the battery pack placed on a placement surface is viewed from the side surface side, only the protruding portions are placed on the placement surface, the four corners include a first corner provided on the bottom surface and the side surfaces, and a second corner provided on the bottom surface and the side surfaces and aligned with the first corner in a first direction, the inner walls of the outer case at the first corner and the second corner are located below the inner walls of the outer case between the first corner and the second corner, a battery pack.

3. The four corners include a third corner and a fourth corner aligned with the third corner in a second direction, the battery pack further comprises a hook portion provided on the bottom surface, at least a part of which is provided between the third corner and the fourth corner, the battery pack according to claim 1 or 2.

Images