JP2019145461A - Battery pack and electrical equipment including the same - Google Patents

Abstract

To provide a battery pack and electrical equipment capable of suppressing breakage and deformation of a battery pack.SOLUTION: A battery pack includes: a housing forming an outer shell and having a pair of battery side rail portions that extend substantially parallel to each other in a longitudinal direction on an upper surface; and a plurality of battery cells housed in the housing. The battery side rail portion includes: a first portion projecting upward from the upper surface and having a side surface; a second portion projecting from the side surface of the first portion in a horizontal direction and having a lower surface; and a connection for connecting between the side surface and the lower surface. In the connection, there is provided a recessed portion which has a curved surface that is recessed, in a horizontal direction, from the side surface to a side opposite to a direction in which the second portion projects.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a battery pack and an electric device including the battery pack.

  Electrical devices such as electric tools are driven using a secondary battery such as a lithium ion battery, and are becoming cordless. For example, in a hand-held power tool that drives a tip tool with a motor, a battery pack containing a plurality of secondary battery cells is used, and the motor is driven by electric energy stored in the battery pack. The battery pack is configured to be attachable to and detachable from the electric tool body. When the voltage drops due to discharge, the battery pack is detached from the electric tool body and charged using an external charging device. An electric tool using such a battery pack is described in Patent Document 1, for example.

JP, 2014-037018, A

  In recent years, cordless electrical devices using battery packs have been increasingly demanded for higher output and longer usage per charge. As a result, the capacity of battery packs has increased and battery packs have become larger. The weight also tends to increase. In addition, since the electric equipment main body tends to increase in size due to the increase in output, the collision energy at the time of dropping or the like tends to increase, so reinforcement as a countermeasure against damage becomes important. In addition, due to the increase in the size of battery packs, electrical devices such as impact wrenches with large vibrations tend to increase in vibration with higher output. The load on the battery pack causes damage to the battery case or the battery pack and the electrical device body. It is important to suppress relative movement.

  Accordingly, an object of the present invention is to provide a battery pack and an electric device that can suppress damage and deformation of the battery pack.

  According to one aspect of the present invention, there is provided a battery pack including a case having a pair of battery side rail portions extending substantially parallel to each other in the front-rear direction on the upper surface, and a plurality of battery cells accommodated in the case. The battery-side rail portion is connected to the first portion having a side surface protruding upward from the upper surface, the second portion having a lower surface protruding from the side surface of the first portion, and the side surface and the lower surface. And a concave portion having a curved surface that is recessed in a direction opposite to a direction in which the second portion protrudes from the side surface in the left-right direction.

  According to still another feature of the present invention, the center of the curved surface may be shifted from the extended line of the side surface in a direction in which the second part protrudes in the left-right direction.

  According to still another feature of the present invention, the battery-side rail portion is open at one end in the front-rear direction and closed at the other end, and the recess is at least in the longitudinal direction of the battery-side rail portion. It may be provided on the open end side. Moreover, you may provide the said recessed part in the whole area of the longitudinal direction of the said battery side rail part. Moreover, the edge part of the said open | release side of the said 1st part may become a curved surface shape, and the recessed dimension of the said recessed part may be smaller than the curved surface of the said curved surface shape.

  According to still another feature of the present invention, a recess dimension from the side surface of the recess may be 2% or more and 15% or less with respect to a width dimension in the left-right direction of the first portion. The radius of the curved surface may be 15% or more and 25% or less with respect to the width dimension of the first portion in the left-right direction. In addition, the vertical dimension of the recess located on the extension of the side surface may be 15% or more and 30% or less with respect to the dimension between the upper surface and the lower surface.

  According to still another feature of the present invention, the length of the curved surface of the recess that is positioned in the direction in which the second portion protrudes from the side surface is an end portion on the opposite side surface side of the second portion from the side surface. It is good also as 20% or less with respect to the length to.

  According to still another aspect of the present invention, the battery-side rail portion has one end side in the front-rear direction opened and the other end side closed, and the second portion has the lower surface on the open end side. The concave portion may be formed along a front-rear direction in which the first portion extends.

  ADVANTAGE OF THE INVENTION According to this invention, the battery pack and electric device which can suppress damage and a deformation | transformation of a battery pack can be provided. In addition, it is possible to obtain an effect simply by changing the corner R shape, without increasing the size of the battery pack or adding new parts, and it is not necessary to change the electrical equipment side, so that an increase in price can be avoided. .

It is sectional drawing of the electric tool which is an example of the electric equipment used as this invention. It is a battery pack mounting part of the electric equipment main body which comprises the electric equipment of FIG. 1, (1) is a bottom view, (2) is a front view. It is an upper perspective view of the battery pack which becomes this invention. It is a downward perspective view of the battery pack used as the present invention. It is the elements on larger scale of the battery side rail part of the battery pack used as this invention. It is sectional drawing of the battery pack used as this invention. It is a figure which shows the load direction at the time of an electric equipment falling when an electric equipment falls. It is a figure which shows the simple model at the time of performing the stress analysis of a battery side rail part. It is a figure which shows the effective range of the shape of the battery side rail part obtained from the stress analysis of FIG. It is a figure which shows an example of the shape which remove | deviated from the effective range of FIG.

  Hereinafter, an impact driver 1 which is an example of an electric tool which is an embodiment of the electric device according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The impact driver 1 is an electric motor for fastening a fastener (screw, etc.) to a workpiece (steel, wood, etc.) by applying rotational force or axial striking force to a tip tool (not shown) such as a bit. It is a power tool.

  In the following description, “up” shown in FIG. 1 is defined as an upward direction, “down” is defined as a downward direction, “front” is defined as a forward direction, and “rear” is defined as a backward direction. Further, when the impact driver 1 is viewed from the rear, “right” is defined as the right direction, and “left” is defined as the left direction. References to dimensions, numerical values, and the like in this specification include not only dimensions and numerical values that completely match the dimensions and numerical values, but also substantially matching dimensions and numerical values (for example, within the range of manufacturing errors). ). Similarly, “same”, “perpendicular”, “parallel”, “match”, “same”, “substantially same”, “substantially orthogonal”, “substantially parallel”, “substantially match”, “substantially flush” Etc.

  The impact driver 1 (electric device) is composed of an electric tool main body (electric device main body) 2 and a battery pack 3, and drives a tip tool and work equipment through a mechanism portion using a rotational driving force by a motor 4. The mechanical part of the electric power tool body 2 includes a speed reduction mechanism 5 and a striking mechanism 6, and a tip tool (not shown) such as a bit is attached to a tip tool mounting part 7 formed at the tip of the output shaft of the striking mechanism 6. .

  The main body portion of the electric power tool main body 2 includes a resin main body housing 20 that is an outer frame forming an outer shape. The main body housing 20 includes a body portion 20a that houses the motor 4, the speed reduction mechanism 5, and the striking mechanism 6, and a handle portion 20b that is formed integrally with the body portion 20a and extends downward from the body portion 20a to be gripped by an operator. The battery pack mounting portion 20c is formed integrally with the handle portion 20b and extends forward from the lower end portion of the handle portion 20b to mount the battery pack 3.

  The motor 4 is a brushless motor, and an inverter circuit board portion 4a on which a magnetic sensor for detecting the rotational position of the brushless motor (rotor) and an inverter circuit having a switching element for controlling the rotation of the brushless motor are mounted. It is fixed to the rear part of the stator. A fan 4 b is fixed to the rotating shaft of the motor 4 at a position in front of the motor 4 and behind the speed reduction mechanism 5.

  A trigger switch 8 that can be operated while being gripped by an operator is provided near the upper end of the handle portion 20b (a connection portion with the body portion 20a). Inside the handle portion 20b, a control unit 10 described later is provided. A connected switch mechanism 9 is provided.

  The battery pack mounting portion 20c is provided with a terminal holder 21 (see FIG. 2) having a battery connection terminal portion 22 that is electrically connected to a terminal portion (not shown) of the battery pack 3 when the battery pack 3 is mounted. It has been. Furthermore, a control unit 10 having a control board on which various circuits such as a microcomputer for controlling the motor 4 are mounted is fixed in the battery pack mounting unit 20c. The control unit 10 is electrically connected to the switch mechanism 9 and the inverter circuit board unit 4a. Details of the battery pack mounting portion 20c will be described later.

  A hammer case 11 is provided in front of the body portion 20 a to accommodate the rear portions of the speed reduction mechanism 5, the striking mechanism 6, and the tip tool mounting portion 7. The hammer case 11 is made of aluminum and has a substantially cylindrical shape. The hammer case 11 accommodates a part of the speed reduction mechanism 5, the striking mechanism 6, and the tip tool mounting portion 7 in this order in the direction toward the front. In the present invention, the main body housing 20 and the hammer case 11 correspond to the housing, and the combination of the impact driver main body (electric device main body or electric tool main body) and the battery pack 3 corresponds to the electric device.

  2A and 2B are views showing the shape of the battery pack mounting portion 20c, where FIG. 2A is a bottom view of the battery pack mounting portion 20c, and FIG. 2B is a front view of the battery pack mounting portion 2c.

  The battery pack 3 is mounted on the battery pack mounting portion 2c by sliding from the front toward the rear with respect to the battery pack mounting portion 20c. A terminal holder 21 having a battery connection terminal portion 22 on the electric device main body side is provided at a lower portion of the battery pack mounting portion 20c. The terminal holder 21 is mainly formed (cast-in) from a synthetic resin molded product. From the base portion 23 made of synthetic resin, a plate-shaped metal terminal, that is, from the positive input terminal 231, the negative input terminal 232, and the battery pack 3 is used. An abnormal signal terminal 233 to which an abnormal signal is input is arranged.

  The positive input terminal 231, the negative input terminal 232, and the abnormal signal terminal 233 are thin plate-like, and their surfaces are perpendicular to the base portion 23, and the longitudinal direction is in the mounting direction (front-rear direction) of the battery pack 3. It is arranged to be located.

  The main body housing 20 is configured by fixing a housing piece divided into two in the left-right direction with screws at a plurality of locations. In addition, the main body housing 20 of FIG. 1 has shown the left side housing piece. On the front lower surface of the battery pack mounting portion 20c, a protruding portion 11 that also serves as a screw boss protrudes, and the protruding portion 11 becomes one of the fixing points of the left and right housing pieces.

  The base portion 23 of the terminal holder 21 is held so as to be sandwiched between the concave sandwiching portions 200 and 200 of each housing piece of the main body housing 20. The terminal holder 21 may be firmly held with respect to the main body housing 20 (battery pack mounting portion 20c), or may be gently held so as to be slightly movable with respect to the main body housing 20. May be.

  The battery pack holding portion 20 c is engaged with a pair of device-side rail groove portions 210 that engage with a pair of battery-side rail portions (described later) of the battery pack 3 and a pair of battery-side rail groove portions (described later) of the battery pack 3. A pair of device-side rail portions 211 are formed. The apparatus side rail groove part 210 and the apparatus side rail part 211 are extended in the front-back direction (sliding direction of the battery pack 3). The apparatus side rail part 211 is located below the apparatus side rail groove part 210 and protrudes inward. That is, the device-side rail portion 211 is formed on the inner side with respect to the outline of the battery pack holding portion 20c, and the bottom surface 212 thereof is more than the battery connection terminal portion 22 (positive electrode input terminal 231, negative electrode input terminal 232, abnormal signal terminal 233). Located below. The device-side rail portion 211 is formed with a recess 211a that engages with a locking portion 42 of the battery pack 3 to be described later. In addition, the apparatus side rail part 211 may be formed so that it may protrude inside with respect to the outline of the electric power tool main body 2 like this Embodiment, or it may be formed outside with respect to the outline of the electric power tool main body 2. You may form so that it may protrude.

  Next, the battery pack 3 will be described with reference to FIGS. 3 is an upper perspective view of the battery pack 3, FIG. 4 is a lower perspective view of the battery pack 3, FIG. 5 is a partially enlarged view of a battery side rail portion of the battery pack 3, and FIG. Note that the front, rear, left, right, and up and down directions when the battery pack 3 is viewed alone will be described as directions shown in FIG.

  The battery pack 3 includes an outer casing formed by a case including an upper case 31 and a lower case 32 that can be divided in the vertical direction. Note that the housing does not have to be composed of an upper case and a lower case, and may be composed of a case divided into left and right or front and rear, or a part of the housing by a separator that holds battery cells. In the present embodiment, a case composed of an upper case 31 and a lower case 32 will be described as a housing. In the upper case 31, two (a pair of) battery side rail portions 33a for engaging with a pair of rail groove portions 210 (device side rail groove portions) formed in the battery pack mounting portion 20c of the electric power tool body 2, A pair of battery-side rail groove portions 33b that engage with a pair of device-side rail portions 211 formed in the battery pack mounting portion 20c are formed on the lower side of the battery-side rail portion 33a, thereby constituting a battery-side rail portion. The battery-side rail portion 33a and the battery-side rail groove portion 33b are formed substantially parallel to each other, and the surface connecting the pair of battery-side rail portions 33a is the upper step surface 34. A flat lower step surface 35 is formed on the front side of the upper case 31, the lower step surface 35 and the upper step surface 34 are formed in a staircase shape, and a stepped portion 36 serving as a vertical surface is formed at a connecting portion thereof. A plurality of slots 37 that are notched from the front to the rear are formed from the stepped portion 36 to the upper step surface 34. The plurality of slots 37 are portions that are notched so as to have a predetermined length in the battery pack mounting direction (front-rear direction) so as to extend rearward from the stepped portion 36, and have a top surface and a vertical surface parallel to the mounting direction. A plurality of connection terminals 38 (see FIG. 6) that can be fitted to the device side terminals of the electric power tool main body 2 or an external charging device (not shown) are arranged in the portions where the cutouts are formed on the surface. .

  On the rear side of the upper step surface 34, a raised portion 39 formed so as to be raised is formed. The raised portion 39 has a shape in which the outer shape is raised above the upper surface 34, and a recessed stopper portion 40 is formed in the vicinity of the center thereof. When the battery pack 3 is mounted on the battery pack mounting portion 20c, the stopper portion 40 becomes a surface that abuts against the protrusion 11 (see FIG. 2) of the battery pack mounting portion 20c. When the protrusion 11 on the power tool main body 2 side relatively moves to a position where it comes into contact with the stopper portion 40, a plurality of terminals 231 to 233 (device side terminals that are battery connection terminal portions 22) disposed on the power tool main body 2 and The plurality of connection terminals 38 arranged in the battery pack 3 come into contact with each other and become conductive. At the same time, the latching portion 42 of the latch 41 of the battery pack 3 jumps out in the left-right direction within the battery-side rail groove 33b formed in the lower part of the battery-side rail portion 33a by the action of the spring, and the device-side rail of the electric power tool body 2 By engaging with the recess 211a formed in the portion 211, the battery pack 3 is prevented from falling off. A display 45 for displaying the remaining capacity of the battery pack 3 is provided behind the raised portion 39 (stopper 40).

  The pair of battery-side rail portions 33a includes a portion (first portion) extending upward from the upper surface of the lower step surface 35, and a portion (second portion) formed so as to project outward from the first portion in the orthogonal direction. ) And is formed linearly from the front to the rear of the battery pack 3. The front side end portion of the battery side rail portion 33 a is an open end, and the rear side end portion is a closed end connected to the front side wall surface of the raised portion 39. The battery side rail portion 33a and the device side rail groove portion 210 of the electric tool main body 2 are engaged, and the battery side rail groove portion 33b and the device side rail portion 211 of the electric tool main body 2 are engaged. When the battery pack 3 is removed from the electric tool main body 2, the latching portion 42 moves to the inside of the battery side rail groove portion 33 b by pushing the button-like latches 41 on both the left and right sides, and the concave portion of the device side rail portion 211. Since the locked state with 211a is released, the battery pack 3 may be moved to the opposite side to the mounting direction in that state.

  Inside the case of the battery pack 3, lithium ion battery cells 43 having a rated voltage of 3.6V are accommodated in two upper and lower stages, five in the upper stage and five in the lower stage. In the present embodiment, the cells 43 are alternately arranged so that the electrodes of the adjacent cells are opposite to each other, and by connecting them with connecting pieces, five of the ten cells are connected in series. Two series cell sets are connected in parallel to form a battery pack 3 with a rated voltage of 18V. A low-capacity battery pack only needs to be connected in series with five cells in the vertical direction. Conversely, a high-capacity battery pack can have two or more battery cells connected in parallel in the vertical direction. Good. Each cell is held in the case by a separator (not shown). A circuit board 44 is provided on the upper cell substantially parallel to the bottom surface of the lower case 32, and a plurality of connection terminals 38 are fixed to the circuit board 44. The circuit board 44 is fixed to the upper surface of the separator. Further, even when the separator constitutes a part of the casing (case), it can be considered that the battery cell is accommodated in the casing.

  Next, the structure of the case (upper case 31 and lower case 32) of the battery pack 3 will be described. The upper case 31 has an upper side wall portion that forms an outer shell. The upper side wall portion is provided with an upper step portion 34, a lower step portion 35, a raised portion 39 and the like of the upper case 31, and extends downward from the upper case upper portion 31a at the front portion of the upper case 31. The front wall 311, a pair of side walls 312 extending downward from the upper case upper part 31 a on both the left and right sides of the upper case 31, and a rear wall 313 extending downward from the upper case upper part 31 a at the rear part of the upper case 31.

  Similarly, the lower case 32 has a lower side wall portion that forms an outline with the upper case 31. The lower side wall portion extends from the bottom wall 321 on the left and right sides of the lower case 32, the bottom wall 321 serving as the bottom surface of the battery pack 3, the front wall 322 extending upward from the bottom wall 321 at the front portion of the lower case 32. A pair of side walls 323 and a rear wall 324 extending upward from the bottom wall 321 at the rear portion of the lower case 32 are configured.

  Covering the upper case 31 from above with a screw (not shown) in a state where the cell unit including the battery cell 43, the separator, the circuit board 44, the connection terminal 38 and the like is accommodated in the lower case 32. Thus, the battery pack 3 is configured.

  Here, the structure of the battery side rail part 33a of the battery pack 3 and the battery side rail groove part 33b is demonstrated. Conventionally, a minute curved surface R is provided at the corner of the rail portion of the battery pack. That is, the rail side surface and the rail upper surface are connected via the curved surface R. The curved surface R indicates a circle with a radius R. As shown in the upper diagram of FIG. 7, when the battery pack is connected to the power tool main body and falls to the ground W or the like first from the battery pack, a load F1 is applied to the rail portion of the battery pack, and the rail is driven by the power tool main body. The portion is pulled, stress concentrates on the rail portion, and the rail portion may be damaged. Further, as shown in the lower diagram of FIG. 7, a load F <b> 2 is applied to the rail portion of the battery pack due to vibration during use of the electric tool. Therefore, the curved surface R is provided in order to suppress breakage of the rail portion. As the curved surface R is increased, the stress concentration is reduced and the possibility of breakage is reduced. On the other hand, when the curved surface R is increased, it is necessary to cut corner portions of the rail portion on the equipment side in accordance with the situation. For this reason, the contact area between the rail portions of the battery pack and the power tool main body is reduced. Further, the configuration in which the rail lower surface 33d of the rail portion is recessed (turned) upward also reduces the contact area between the rail portions of the battery pack and the power tool main body. Therefore, rattling is likely to occur when the rail portion is deformed or worn due to vibration generated during use of the electric tool, and as a result, the battery pack vibration increases, resulting in electrical chattering between terminals. It is conceivable that the connection is interrupted or, in the worst case, the battery pack is detached from the power tool body when the power tool is used.

  Furthermore, if the curved surface R is enlarged, it may not be possible to maintain compatibility with the existing power tool body. When a battery pack having a large curved surface R is used, a dedicated power tool body must be used. This is very inconvenient for the user.

  Further, as a means for reducing the stress applied to the rail portion of the battery pack, it is conceivable to make the rail portion larger and longer as a whole, but this leads to an overall increase in the size of the electric tool including the electric tool body. In addition, it is not desirable from the viewpoint of compatibility with the conventional electric power tool body.

  Therefore, in the present invention, it is possible to maintain compatibility with the conventional power tool main body without increasing the size by forming a curved shape having a curved surface as a concave portion recessed inward at the corner R of the battery pack. Possible configuration.

  As shown in FIGS. 4 and 5, the battery pack 3 includes a battery side rail portion 33a and a battery side rail groove portion 33b. Corner portion 33e serving as a connection portion between rail side surface 33c serving as a side surface of the first portion (battery side rail groove portion 33b) of battery side rail portion 33a and rail lower surface 33d serving as a lower surface of battery side rail portion 33a (second portion). Was formed into a curled shape having a curved surface R recessed inward. Further, a curved or tapered corner portion 33f is provided at the open end of the battery side rail portion 33a, and a tapered corner portion 33g is also provided at the open end of the battery side rail groove portion 33b. Here, the curved surface R is a circle in a state where the center of the circle with the radius R is not positioned on the extension line of the rail side surface 33c but is shifted in the left-right direction, specifically, shifted outward from the rail side surface 33c. The curved surface R at the time of drawing is shown.

  As described above, it is a common means to provide the curved surface R in order to suppress the occurrence of stress concentration at the corner 33e. However, if the twisted shape is not an appropriate shape, the effect of suppressing the stress concentration is reduced, and in some cases, the reverse effect may be obtained. Even if the stress is further lowered, if the rigidity of the rail portion is reduced and the rail portion is easily deformed greatly, the vibration of the battery pack is increased or the battery pack 3 is easily detached from the battery pack mounting portion 20c. Therefore, it leads to a performance fall and the fall of an effect | action.

  In the present invention, in order to determine an appropriate bend shape in order to solve these problems, an optimum bend shape could be obtained by performing stress analysis. The optimum beat will be described with reference to FIGS. FIG. 8A is a simplified view of the rail portion (battery side rail portion 33a and battery side rail groove portion 33b) of the battery pack 3 of FIG. 3 as viewed from the front (side first inserted into the battery pack mounting portion 20c). It has been replaced with a model. A state in which the lower surface (corresponding to the lower surface 35) of the battery pack 3 is constrained (fixed) and a constant load F3 is applied from the lower side to the upper side at the open end in the left-right direction of the rail lower surface 33d Yes. Here, the load F3 is assumed to be a load that the battery side rail portion 33a (rail lower surface 33d) receives from the device side rail portion 211 in a state where the battery pack 3 is connected to the battery pack mounting portion 20c.

  FIG. 8B shows a battery pack in which the rail portion of FIG. 1 is replaced with a simple model, and the curved surface R of the corner portion 33e has a curled shape. Here, regarding the dimensions of each part, the width of the rail part is B1, the height of the portion (battery side rail groove part 33b) where the main body side rail part is inserted is H1, and the outside of the rail side surface 33c of the battery side rail part 33a. The amount of protrusion to W1 is W1, the turning width of the corner 33e from the rail side 33c (the horizontal dimension of the turning portion) is B2, and the turning height of the turning portion (from the rail side surface 33c to the rail lower surface 33d in the vertical direction) The height dimension of the turn R) is H2, and the width dimension (protrusion width) from the rail side surface 33c to the place where the turn portion is connected to the rail lower surface 33d is W2. Here, as described above, it should be noted that the turn portion is not semicircular, that is, the center of the curved surface is shifted outward from the race side surface 33c.

  As a result of performing stress analysis using this simple model, FIGS. 9A and 9B show a range in which the effect of suppressing stress concentration while maintaining rigidity is large. In FIG. 9A, the horizontal axis is the ratio B2 / B1 (%) between the horizontal width B2 in the horizontal (left and right) direction and the width B1 of the rail portion, and the vertical axis is the height H2 in the height (vertical) direction. And a ratio H2 / H1 (%) of the height H1 of the groove portion of the rail portion. FIG. 9B is a graph in which the horizontal axis is B2 / B1 (%) as in FIG. 9A, and the vertical axis is the ratio R / B1 (%) between the dimension of the curved surface R and the horizontal width B1. It is a thing.

  In FIG. 9, the shaded portion (effective range) is a range in which the increase in the deformation amount of the rail portion can be suppressed to 20% or less while reducing the stress by 5% or more, and the stress while suppressing the increase in the deformation amount of the rail to the minimum. Can be reduced. Within this range, the increase in rail deformation could be suppressed to 5% while reducing the stress by 15%, and the greatest effect could be obtained.

  In FIG. 9 (a), when it deviates from the hatched portion (effective range), the phenomenon of the defect differs depending on the deviating direction, and is roughly classified into regions A to D. Region A is a case where the turning width B2 of FIG. 8 is small and the turning height H2 is large. In this case, the turn R of the corner 33e and the rail lower surface 33d cannot be connected continuously, resulting in an edge (corner), or the turn and the rail lower surface 33d so that they can be connected continuously. However, in both cases, stress and deformation increase, resulting in an undesirable shape. Further, increasing the protrusion width W2 and the turning height H2 reduces the contact area with the rail portion of the electric power tool main body as described above, resulting in increased wear between the rail portions and ease of removal of the battery pack. This is not preferable.

  In the region B, both the protruding width H2 and the turning width B2 become large, and the deformation becomes excessive with respect to the load F3 in FIG. 8, and even if the curved surface R is increased due to the decrease in the thickness of the stress and bending, the effect is small and cannot be said to be effective. In the region C, the pop-out width H2 and the turning amount B2 are both small, and an effect cannot be obtained. In the region D, the protrusion width H2 is small and the turning amount B2 is large, so that a small curved surface R is likely to occur, and the stress becomes excessive.

  Similarly, in FIG. 9B, when the hatched portion (effective range) is deviated, the phenomenon of the defect differs depending on the deviated direction, and is roughly divided into regions A to D as in FIG. 9A. . Region A is a case where the turn width B2 of FIG. 8 is small and the curved surface R of the corner 33e is large. In order to realize this, the curved surface R of the corner 33e and the rail lower surface 33d cannot be connected continuously, resulting in an edge, or the ringed portion and the rail lower surface 33d so that they can be connected continuously. However, in both cases, stress and deformation increase, resulting in an undesirable shape. Further, increasing the protrusion width W2 and the turning height H2 reduces the contact area with the rail portion of the electric power tool main body as described above, resulting in increased wear between the rail portions and ease of removal of the battery pack. This is not preferable.

  In the region B, both the curved surface R and the turning width B2 become large, and the deformation becomes excessive with respect to the load F3 in FIG. In the area C, the curved surface R and the turning width B2 are both small, and an effect cannot be obtained. In the region D, since the curved surface R is small and the turning width B2 is large, the stress becomes excessive.

  FIG. 10 shows an example of a shape outside the effective range in FIGS. 9 (a) and 9 (b). These shapes indicate that no effect can be obtained if the dimensions of the turning width B2, the turning height H2, and the protruding width W2 are too large or too small compared to the original shape (conventional shape). Yes, corresponding to each of the areas A to D in FIGS. 9 (a) and 9 (b).

  FIG. 8B shows an example of the optimum shape. Specifically, B2 / B1 is 6.7% for an appropriate value of 2 to 15%, H2 / H1 is 18.9% for an appropriate value of 15 to 30%, and R / B1 is an appropriate value of 15 to 35. % Is 17.8%, and W2 / W1 is 11.0% for an appropriate value of 5 to 20%. Note that this value is a value that does not cause a problem even if some variation occurs in consideration of tolerances.

  FIG. 9 shows the result of the examination with a simple model. In FIG. 5, the actual rail shape of the battery pack 3 is such that the turning width B2 of the corner 33e is a rail side 33c and a rail perpendicular to the rail side 33c. It is desirable that the value be equal to or less than the value of the curved surface R provided at the corner 33g with the end face of the open end (entrance side) of the part. That is, it is desirable that the turning portion is located within the range of the curved surface R of the corner portion 33g in the direction of turning width B2. In other words, it is desirable that no turning portion is formed on the inner side (left side in FIG. 5) of the curved surface R of the corner portion 33g. When the value of the turning width B2 is larger than the value of the curved surface R provided at the corner 33g at the corner 33e, there is a region perpendicular to the intersection of the corner 33g and the corner 33e. This is because stress concentration occurs in the region, and the rail portion may be damaged.

  Moreover, the area | region of the turn part provided in the corner | angular part 33e is uniform seeing from the insertion direction (direction where a rail part is extended) of an apparatus side rail part, and the rail lower surface 33d provided in the outward direction from the upper part of the rail side surface 33c. The open end (entrance side) of the rail lower surface 33d is a corner portion 33f that is inclined in a direction extending upward from the rail lower surface 33d so that the device side rail portion can be easily inserted. Further, the corner portion 33e that is bent inward from the rail side surface 33c is branched from the corner portion 33f that is inclined when the rail lower surface 33d is inclined upward on the open end side (entrance side) of the rail portion. It is desirable to form it so as to extend straight along the open end (entrance) side of the rail portion along 33d. With this configuration, an effect of dispersing stress can be expected at a place where a relatively high stress is likely to be generated on the entrance side of the rail portion.

  FIG. 4 shows a case where the corner portion 33e of the rail portion is provided with a uniform turning portion from the entrance side (open end side) to the root side (closed end side). However, it is not always necessary to provide this bend. For example, even if the corner portion 33e near the entrance and the base portion of the rail portion is provided with a turn portion, and the corner portion 33e located between them is not provided with a turn portion, the rail lower surface 33d is more than necessary even if it is a normal curved surface R. Can be prevented from being deformed.

  As described above, according to the present invention, even when a large load (stress) is generated in the battery pack 3, it is possible to suppress the deformation and breakage of the rail portion, and to maintain a good state and Electrical equipment can be provided.

  Although the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the electric tool main body having a trigger switch and a motor has been described as the electric device main body. It can be widely used for other electric tool bodies, lighting devices, acoustic devices, electric devices such as electric devices. Further, the arrangement and shape of the slots on the battery pack side and the arrangement and shape of the terminals on the electric device main body side are not limited to the above-described configurations, but may be other configurations.

  1 is an electric device, 2 is an electric device main body, 3 is a battery pack, 4 is a motor, 5 is a deceleration mechanism, 6 is a striking mechanism, 7 is a tip tool mounting portion, 8 is a trigger switch, 9 is a switch mechanism, and 10 is a control , 11 is a hammer case, 20 is a body housing, 21 is a terminal holder, 22 is a battery connection terminal portion, 23 is a base portion, 33a is a battery side rail portion, 33b is a battery side rail groove portion, 33c is a rail side surface, 33d is Rail lower surfaces 33e, 33f, and 33g are corners.

Claims (11)

A housing having a pair of battery-side rail portions that form an outer shell and extend substantially parallel to each other in the front-rear direction on the upper surface;
A plurality of battery cells housed in the housing,
The battery side rail portion projects upward from the upper surface and has a side surface, a second portion projecting from the side surface of the first portion in the left-right direction and having a lower surface, and a connection connecting the side surface and the lower surface. And
The battery pack according to claim 1, wherein a concave portion having a curved surface that is recessed in a direction opposite to a direction in which the second portion protrudes from the side surface in the left-right direction is provided in the connection portion.   2. The battery pack according to claim 1, wherein a center of the curved surface is shifted from a line extending from the side surface in a direction in which the second portion protrudes in the left-right direction. The battery side rail portion has one end side in the front-rear direction opened and the other end side closed,
3. The battery pack according to claim 1, wherein the concave portion is provided at least on the open end side in the longitudinal direction of the battery side rail portion.   4. The battery pack according to claim 3, wherein the concave portion is provided in an entire region in a longitudinal direction of the battery side rail portion. The battery side rail portion has one end side in the front-rear direction opened and the other end side closed,
The open end of the first part has a curved shape,
The battery pack according to any one of claims 1 to 4, wherein a recess size of the recess is smaller than a curved surface of the curved shape.   6. The recess size from the side surface of the recess is set to 2% or more and 15% or less with respect to the width dimension in the left-right direction of the first portion. Battery pack.   7. The battery pack according to claim 1, wherein a radius of the curved surface is set to 15% or more and 25% or less with respect to a width dimension in a left-right direction of the first portion.   8. The vertical dimension of the concave portion located on the extension of the side surface is set to 15% or more and 30% or less with respect to the dimension between the upper surface and the lower surface. The battery pack according to any one of the above.   In the curved surface of the concave portion, the length of the second portion protruding in the direction in which the second portion protrudes from the side surface is 20% or less with respect to the length from the side surface to the end portion on the opposite side surface of the second portion. The battery pack according to claim 1, wherein the battery pack is a battery pack. The battery side rail portion has one end side in the front-rear direction opened and the other end side closed,
The second portion has a corner portion whose upper surface is inclined or curved upward on the open end side,
The battery pack according to claim 1, wherein the recess is formed along a front-rear direction in which the first portion extends. A battery pack connection part to which the battery pack according to any one of claims 1 to 10 is connected;
And an electric device having a drive unit driven by the battery pack connected to the battery pack connection unit.