Patent Description:
Patent Literature <NUM> discloses a rotary tool as a type of electric tool. The housing of this rotary tool is made up of: a cylinder portion that houses a motor and a driving unit to be driven in rotation by the motor; and a grip portion provided to protrude from the cylinder portion. A battery pack serving as a power supply for the rotary tool is attached to the grip portion.

The rotary tool may be put on a floor surface or the ground to stand by itself thereon with its battery pack facing down. However, putting the rotary tool violently onto the floor surface or the ground could apply impact to the battery pack. If the rotary tool is handled in such a careless manner frequently, then the application of the impact to the battery pack could cause leakage of liquid from a lithium-ion battery used in the battery pack and other inconveniences. <CIT> describes a power tool, such as an impact driver, including a motor housing that houses a motor, and a battery-mount part to which a battery pack having a rated voltage of <NUM> V is mountable. A ratio of the maximum width of the motor housing to the maximum width of the battery pack is <NUM> or less. A forward/reverse-switching lever is slidable in a left-right direction to change the rotational direction of the motor and is disposed between the motor housing and the battery pack. A maximum-slide position of the forward/reverse-switching lever in the left-right direction is inward of a ground plane when the power tool is laid horizontally on its side on the ground plane. <CIT> describes a solid battery including at least one first laminate body in which a first electrolyte layer, a first positive electrode layer, a first current collecting layer, and a second positive electrode layer are laminated in this order; at least one second laminate body in which a second electrolyte layer, a first negative electrode layer, a second current collecting layer, and a second negative electrode layer are laminated in this order; a first insulating layer connected to at least part of a side surface portion of the first laminate body; and a second insulating layer connected to at least part of a side surface portion of the second laminate body. Each of the first current collecting layer and the second current collecting layer has ionic conductivity of <NUM>-<NUM>/cm or lower, and each of the first insulating layer and the second insulating layer has ionic conductivity of <NUM>-<NUM>/cm or lower.

An object of the present disclosure is to provide an electric tool that may reduce the chances of causing inconvenience to its battery pack and a battery pack for use in such an electric tool.

Particular embodiments are set forth in the dependent claims.

An electric tool <NUM> according to an exemplary embodiment is a handheld electric tool as shown in <FIG>. The electric tool <NUM> may be implemented as, for example, an electric screwdriver, an electric drill, an electric wrench, or an electric grinder.

The electric tool <NUM> according to this embodiment includes a body portion <NUM>, a grip portion <NUM>, and a battery pack <NUM>.

The body portion <NUM> includes: a tool attachment member <NUM> to which a tool <NUM> is attached; a driving unit <NUM> to drive the tool <NUM>; and a transmission unit <NUM> to transmit the driving force of the driving unit <NUM> to the tool <NUM>.

The grip portion <NUM> includes a gripping part <NUM> designed to be held by a user with his or her hand <NUM>.

The battery pack <NUM> supplies power to the driving unit <NUM>.

Out of two end portions <NUM>, <NUM>, interposing the gripping part <NUM> between them, of the grip portion <NUM>, the body portion <NUM> is connected to one end portion <NUM> and the battery pack <NUM> is attached to the other end portion <NUM>.

The electric tool <NUM> in its entirety, including the body portion <NUM>, the grip portion <NUM>, and the battery pack <NUM>, may stand by itself with a bottom surface <NUM>, opposite from the grip portion <NUM>, of the battery pack <NUM> put on a mounting surface (such as the ground <NUM>).

The battery pack <NUM> includes a plurality of all-solid-state batteries <NUM>, each of which is formed in a sheet shape.

The plurality of all-solid-state batteries <NUM> are stacked one on top of another.

The electric tool <NUM> according to this embodiment may stand by itself in its entirety with the bottom surface <NUM> of the battery pack <NUM> put on the mounting surface. Thus, putting the electric tool <NUM> violently onto the mounting surface with the battery pack <NUM> facing down could apply impact to the battery pack <NUM>. In this embodiment, the battery pack <NUM> includes all-solid-state batteries <NUM> with higher impact resistance than a liquid battery such as a lithium-ion battery. This may reduce, even if impact is applied to the battery pack <NUM>, the chances of causing abnormality to the battery pack <NUM>. Thus, an electric tool <NUM> that may reduce the risk of causing damage may be provided. In the following description of this exemplary embodiment, an electric tool <NUM> of the shape in which out of two end portions <NUM>, <NUM> of the grip portion <NUM>, one end portion <NUM> is connected to the body portion <NUM> and the battery pack <NUM> is attached to the other end portion <NUM> (i.e., a so-called "gun type" electric tool <NUM>) will be described.

The battery pack <NUM> included in the electric tool <NUM> includes a battery case <NUM> to house the all-solid-state batteries <NUM> therein.

The battery pack <NUM> includes all-solid-state batteries <NUM>. This may reduce the chances of causing abnormality such as liquid leakage to the battery pack <NUM>, compared to a situation where a liquid battery is used. Thus, a battery pack <NUM> that may reduce the chances of causing inconveniences to itself is provided.

Next, the configuration of an electric tool according to an exemplary embodiment will be described in detail with reference to <FIG>. Note that the numerical values, shapes, materials, positions of constituent elements, relative positions between the constituent elements, their connection, and other specifics to be described below are all examples and should not be construed as limiting the scope of the present disclosure. The drawings to be referred to in the following description of embodiments are all schematic representations. That is to say, the ratio of the dimensions (including thicknesses) of respective constituent elements illustrated on the drawings does not always reflect their actual dimensional ratio. Also, in the following description, the X-axis direction and Z-axis direction shown in <FIG>, <FIG>, and <FIG> will define the forward/backward direction and upward/downward direction, respectively, and the Y-axis direction shown in <FIG> will define the rightward/leftward direction. More specifically, the positive X-axis direction will define the forward direction, the positive Y-axis direction will define the rightward direction, and the positive Z-axis direction will define the upward direction. However, these directions are only examples and should not be construed as limiting the direction in which the electric tool <NUM> is used. Furthermore, the arrows shown on the drawings to indicate the respective directions are just given there as an assistant to description and are insubstantial ones.

The electric tool <NUM> includes the body portion <NUM>, the grip portion <NUM>, and the battery pack <NUM> as shown in <FIG>. In this embodiment, the body portion <NUM> and the grip portion <NUM> are provided integrally with each other and a tool body <NUM> is made up of the body portion <NUM> and the grip portion <NUM>.

First, the tool body <NUM> made up of the body portion <NUM> and the grip portion <NUM> will be described.

The body portion <NUM> may be, for example, a molded product of a synthetic resin with electrical insulation properties. The body portion <NUM> is formed in the shape of a cylinder extending in the forward/backward direction.

At the frontend of the body portion <NUM>, provided is the tool attachment member <NUM>, to which a tool <NUM> such as a tip tool is attached. Inside the body portion <NUM>, housed are the driving unit <NUM> and the transmission unit <NUM> described above.

The tool attachment member <NUM> is provided for the body portion <NUM> to be rotatable around a rotational axis aligned with the forward/backward direction. Multiple different types of tools <NUM> are provided for various types of machining work to be done using this electric tool <NUM>. Any desired one of the tools <NUM> may be selectively attached to the tool attachment member <NUM> and used to have an intended type of machining work done. Examples of such types of tools <NUM> include a screwdriver bit for fastening a screw, a drill bit for drilling a hole, and a socket for fastening a nut.

The driving unit <NUM> includes an electric motor to be driven with the electric power supplied from the battery pack <NUM>.

The transmission unit <NUM> transmits the driving force of the driving unit <NUM> to the tool attachment member <NUM>. The transmission unit <NUM> is coupled to an output shaft of the driving unit <NUM> and transmits the rotational force of the driving unit <NUM> to the tool attachment member <NUM>, thereby rotating the tool attachment member <NUM>. Optionally, the transmission unit <NUM> may include a speed reducer mechanism, a clutch mechanism, and an impact mechanism, for example.

The grip portion <NUM> extends downward from a part of the peripheral surface of the body portion <NUM>. The longitudinal axis of the grip portion <NUM> is aligned with the upward/downward direction. At the middle of the grip portion <NUM> in the upward/downward direction (at the middle of its length), provided is the gripping part <NUM> to be held by the user with his or her hand <NUM> (see <FIG>). The part surrounded with the two-dot chain L1 (see <FIG>) of the grip portion <NUM> is the gripping part <NUM>. The grip portion <NUM> includes two end portions <NUM>, <NUM>, the upper one <NUM> of which is located opposite from the lower one <NUM> with respect to the gripping part <NUM>. The upper end portion <NUM> is connected to the body portion <NUM>. At the lower end portion <NUM>, provided is a battery attachment portion <NUM> to which the battery pack <NUM> is attached.

A trigger <NUM> is provided on a front portion of the gripping part <NUM> of the grip portion <NUM> to be located adjacent to the end portion <NUM> connected to the body portion <NUM>. The trigger <NUM> is an operating member that accepts an operating command entered by the user to control the rotation of the driving unit <NUM>. The trigger <NUM> is operated by the user with the index finger, for example, of his or her hand <NUM> holding the grip portion <NUM>.

The battery attachment portion <NUM> is provided integrally with the lower end portion <NUM> of the grip portion <NUM>. The battery attachment portion <NUM> is formed to protrude perpendicularly to the upward/downward direction from the lower end portion <NUM> of the grip portion <NUM>. The battery attachment portion <NUM> is formed in the shape of a box, of which the dimension in the upward/downward direction is smaller than its dimension in the forward/backward direction and its dimension in the rightward/leftward direction. To the bottom of the battery attachment portion <NUM>, the battery pack <NUM> is attached removably. The lower surface of the battery attachment portion <NUM> is provided with a recess into which an upper portion of the battery pack <NUM> is inserted.

In this embodiment, a control unit <NUM> (see <FIG>), including a circuit board on which a circuit for controlling the driving unit <NUM> and other components are mounted, is housed inside the battery attachment portion <NUM>. In response to the operation of pulling the trigger <NUM>, the control unit <NUM> may switch the ON/OFF states of the driving unit <NUM>. In addition, according to the manipulative variable of the operation of pulling the trigger <NUM> (i.e., depending on how deep the trigger <NUM> has been pulled), the control unit <NUM> also controls the rotational velocity of the driving unit <NUM> (i.e., the rotational velocity of the tool <NUM> attached to the tool attachment member <NUM>).

In addition, a suspension fitting <NUM> (see <FIG>) for use to suspend the electric tool <NUM> from, for example, a working belt <NUM> (see <FIG>) of the user <NUM> of the electric tool <NUM> is attached to the battery attachment portion <NUM>. The suspension fitting <NUM> includes a fixing portion <NUM> to be inserted into a hole <NUM> provided through a side surface of the battery attachment portion <NUM> and fixed thereto with a screw, for example, and a U-hook <NUM>, one end portion of which is coupled to the fixing portion <NUM>. Hooking the hook <NUM> on his or her working belt <NUM>, for example, allows the user <NUM> to move or do some type of work other than the machining work that requires the use of the electric tool <NUM> while suspending the electric tool <NUM> from the working belt <NUM>.

In this embodiment, the suspension fitting <NUM> is provided for the grip portion <NUM>. Alternatively, the suspension fitting <NUM> may be attached to the body portion <NUM>. That is to say, the electric tool <NUM> may further include the suspension fitting <NUM> which is attached to at least one of the body portion <NUM> or the grip portion <NUM> to suspend the electric tool <NUM> from an object. This allows the electric tool <NUM> to be held suspended from the object.

The battery pack <NUM> serving as a power supply for the electric tool <NUM> will be described with reference to <FIG>.

The battery pack <NUM> serves as a power supply that allows the electric tool <NUM> to operate. The battery pack <NUM> includes the power storage unit <NUM> including the all-solid-state batteries <NUM> and the battery case <NUM> to house the power storage unit <NUM> therein. The battery case <NUM> is a molded product of a synthetic resin having electrical insulation properties and is formed in the shape of a box.

In the upper part of the battery case <NUM>, a rectangular parallelepiped fitting portion <NUM>, which is raised by one step with respect to right and left side portions, is provided along a centerline in the rightward/leftward direction as shown in <FIG>. At the frontend of the fitting portion <NUM>, three slits <NUM> are provided to be spaced apart from each other in the rightward/leftward direction. Each slit <NUM> is provided through the front and upper surfaces of the fitting portion <NUM> and extends in the forward/backward direction. Inside each slit <NUM>, provided is a connection terminal portion <NUM> to be electrically connected to a feeder connection terminal provided in a lower part of the grip portion <NUM>. Each connection terminal portion <NUM> is electrically connected to the power storage unit <NUM> housed inside the battery case <NUM>. In addition, on the upper surface of the fitting portion <NUM>, provided is a second connector <NUM> to be electrically connected to a first connector for transmitting signals, which is provided in a lower part of the grip portion <NUM>. The second connector <NUM> is electrically connected to, for example, a circuit board <NUM> (see <FIG>) housed inside the battery case <NUM>. The circuit board <NUM> acquires battery information about the battery pack <NUM> (such as the voltage value and temperature of the power storage unit <NUM>) and outputs the battery information to the control unit <NUM> provided inside the battery attachment portion <NUM>. In addition, the right and left side surfaces of the fitting portion <NUM> have a plurality of insert grooves <NUM>, to which a plurality of hook pieces <NUM> (see <FIG>) provided inside a recess on the lower surface of the battery attachment portion <NUM> are respectively inserted.

In this embodiment, to attach the battery pack <NUM> to the battery attachment portion <NUM>, the tool body <NUM> is moved downward (as indicated by the arrow A1 in <FIG>) from over the battery pack <NUM> as shown in <FIG>, thereby inserting the fitting portion <NUM> of the battery pack <NUM> into the recess on the lower surface of the battery attachment portion <NUM>. Thereafter, sliding the tool body <NUM> forward (as indicated by the arrow A2 in <FIG>) with respect to the battery pack <NUM> allows the hook pieces <NUM> of the battery attachment portion <NUM> to be inserted into the insert grooves <NUM>. A lock piece <NUM> is disposed behind the frontmost one of the plurality of insert grooves <NUM>. The lock piece <NUM> is biased upward by an elastic member such as a spring. When the battery pack <NUM> is attached to the battery attachment portion <NUM>, the lock piece <NUM> is pressed downward by the hook piece <NUM>, thus allowing the hook piece <NUM> to move inside the insert groove <NUM>. Thereafter, when the hook piece <NUM> reaches the deepest part of the insert groove <NUM>, the lock piece <NUM> is pressed by the spring to move upward and reach the vicinity of the rear opening of the insert groove <NUM>. As a result, attempting to slide the tool body <NUM> backward with respect to the battery pack <NUM> brings the hook piece <NUM> inserted into the front insert groove <NUM> into contact with the lock piece <NUM>, thus regulating the backward slide of the tool body <NUM>. This allows the battery pack <NUM> to be kept attached to the battery attachment portion <NUM>.

As can be seen, according to this embodiment, the battery pack <NUM> is attached to the grip portion <NUM> by sliding the battery pack <NUM> in the slide direction (X-axis direction) aligned with the bottom surface <NUM> of the battery pack <NUM>. That is to say, when the user <NUM> holds the grip portion <NUM> such that the longitudinal axis of the grip portion <NUM> is aligned with the upward/downward direction, the slide direction of the battery pack <NUM> will be aligned with the direction perpendicular to the upward/downward direction that is the direction of gravity. This reduces the risk of the gravitational force applied to the battery pack <NUM> causing the battery pack <NUM> to move in the slide direction, thus reducing the chances of the battery pack <NUM> disengaging itself from the grip portion <NUM>.

Note that in a state where the battery pack <NUM> is attached to the battery attachment portion <NUM>, the connection terminal portion <NUM> is electrically connected to the connection terminals of the battery attachment portion <NUM> and power required for operation is supplied from the power storage unit <NUM> to the control unit <NUM>, the driving unit <NUM>, and other components. In addition, the second connector <NUM> is electrically connected to the first connector of the battery attachment portion <NUM>, the circuit board <NUM> housed in the battery case <NUM> and the control unit <NUM> are also electrically connected to each other, and the battery information is output from the circuit board <NUM> to the control unit <NUM>.

On the other hand, to remove the battery pack <NUM> from the battery attachment portion <NUM>, an operating member provided for the battery case <NUM> is operated to move the lock piece <NUM> downward and make the hook pieces <NUM> ready to move out of the insert grooves <NUM>. In this state, the tool body <NUM> is slid backward (i.e., in the direction opposite from the one indicated by the arrow A2 in <FIG>) with respect to the battery pack <NUM> to move the hook pieces <NUM> out of the insert grooves <NUM>. Then, moving the tool body <NUM> upward (i.e., in the direction opposite from the one indicated by the arrow A1 in <FIG>) with respect to the battery pack <NUM> makes the battery pack <NUM> removable from the tool body <NUM>.

As can be seen, according to this embodiment, the battery pack <NUM> is attachable to, and removable from, the grip portion <NUM> (of the tool body <NUM>). Thus, when the battery level of the battery pack <NUM> becomes low, the user just needs to remove the battery pack <NUM> from the grip portion <NUM> and attach a charged battery pack <NUM> as a replacement to the grip portion <NUM>. This allows the user to continue his or her machining work using the electric tool <NUM>.

Furthermore, the battery pack <NUM> is attached to the end portion <NUM> of the grip portion <NUM> which is located adjacent to the little finger <NUM> of the user <NUM> who grips the grip portion <NUM> as shown in <FIG>. Thus, the end portion <NUM>, located adjacent to the thumb of the user <NUM>, of the grip portion <NUM> is connected to the body portion <NUM>, thus achieving the advantage of allowing the user <NUM> to focus on the target more easily with his or her eyes while he or she is doing machining work with the tool <NUM> brought into contact with the workpiece.

The power storage unit <NUM> is made up of a plurality of all-solid-state batteries <NUM>, each of which is formed in a sheet shape as shown in <FIG> and <FIG>. The plurality of all-solid-state batteries <NUM> are connected in either series or parallel according to the voltage or capacity required. In this embodiment, the power storage unit <NUM> includes five all-solid-state batteries <NUM> which are connected together in series. However, the number and connection mode (which is either series or parallel) of the all-solid-state batteries <NUM> that form the power storage unit <NUM> may be changed as appropriate according to the voltage or capacity required.

In this embodiment, the respective weights of the body portion <NUM> and the battery pack <NUM> are set such that the center of mass of the electric tool <NUM> is located in the grip portion <NUM>. Recently, as electric motors have had their size reduced and their output increased, attempts have been made to reduce the weight of the body portion <NUM> that houses the driving unit <NUM>. Meanwhile, there have been increasing demands for increasing the capacity of the battery pack <NUM> to extend the maximum operating hours. As the capacity of the battery pack <NUM> has been increased to meet such demands, the battery pack <NUM> tends to increase its weight. In this manner, as the battery pack <NUM> increases its weight while the battery pack <NUM> has its weight reduced, the center of mass of the electric tool <NUM> could shift toward the battery pack <NUM>. If the center of mass of the electric tool <NUM> is located in the vicinity of the battery pack <NUM>, the reaction applied to the hand <NUM> of the user who is holding the grip portion <NUM> during the machining work increases. In this embodiment, the power storage unit <NUM> includes the all-solid-state battery <NUM> which is lighter in weight than a liquid battery such as a lithium-ion battery, thus reducing an increase in the weight of the battery pack <NUM> while contributing to increasing the capacity, compared to a situation where the power storage unit <NUM> includes a liquid battery. This enables, even when the capacity of the battery pack <NUM> is increased, keeping the center of mass of the electric tool <NUM> located in the gripping part <NUM> of the grip portion <NUM> and thereby reducing the reaction applied to the hand of the user who is holding the grip portion <NUM> during the machining work, thus contributing to increasing the handiness of the electric tool <NUM>.

In this case, if impact force is applied to the power storage unit <NUM> perpendicularly to the direction in which the all-solid-state batteries <NUM> are stacked one on top of another, then peeling or misalignment will occur between the plurality of all-solid-state batteries <NUM> that are stacked one on top of another, thus possibly causing instability in electrical connection between the plurality of all-solid-state batteries <NUM>. On the other hand, if impact force is applied to the power storage unit <NUM> in the direction in which the all-solid-state batteries <NUM> are stacked one on top of another, then peeling or misalignment will hardly occur between the plurality of all-solid-state batteries <NUM> that are stacked one on top of another, thus reducing the chances of causing instability in electrical connection between the plurality of all-solid-state batteries <NUM>. In this embodiment, the direction in which the plurality of all-solid-state batteries <NUM> are stacked one on top of another is aligned with the line segment that connects together the two end portions <NUM>, <NUM>, interposing the gripping part <NUM> between them, of the grip portion <NUM> (i.e., the Z-axis direction). This reduces the damage to be done to the power storage unit <NUM> by the impact applied to the power storage unit <NUM> in the direction aligned with the Z-axis direction.

Furthermore, in this embodiment, the direction in which the plurality of all-solid-state batteries <NUM> are stacked one on top of another is aligned with a direction perpendicular to the bottom surface <NUM> of the battery pack <NUM>. As used herein, the "direction perpendicular to the bottom surface <NUM>" refers to the direction perpendicular to the mounting surface (e.g., the ground surface <NUM>) on which the electric tool <NUM> is mounted (i.e., the upward/downward direction) and is the Z-axis direction shown in <FIG>. Therefore, if the electric tool <NUM> is put with impetus onto the mounting surface, then impact force is applied in the direction in which the plurality of all-solid-state batteries <NUM> are stacked one on top of another, thus reducing the chances of causing peeling or misalignment between the plurality of all-solid-state batteries <NUM> that are stacked one on top of another. This may reduce the chances of causing deterioration in the electrical performance of the battery pack <NUM>.

Also, in this battery pack <NUM>, the number, area, and connection mode of the all-solid-state batteries <NUM> that form the power storage unit <NUM> may be changed as appropriate according to the voltage and capacity required. The voltage value of the power storage unit <NUM> depends on, for example, the voltage values of the respective all-solid-state batteries <NUM> and the number of the all-solid-state batteries <NUM> that are connected together in series. The capacity of the power storage unit <NUM> depends on, for example, the respective areas of the all-solid-state batteries <NUM> and the number of the all-solid-state batteries <NUM> that are connected together in parallel. For example, <FIG> is a side view of a battery pack 30B including a power storage unit <NUM> in which eight all-solid-state batteries <NUM> are connected together in series. In this battery pack 30B, a larger number of all-solid-state batteries <NUM> are connected together in series than in the battery pack <NUM> described above, and therefore, the voltage when the battery pack 30B is fully charged is set at a higher voltage than in the battery pack <NUM>. Note that the number of the battery packs of different types does not have to be two. Rather, multiple different types of battery packs <NUM>, of which respective voltage values and/or capacities are different from each other, are suitably prepared. In that case, one battery pack <NUM>, selected from the multiple different types of battery packs <NUM>, may be attached to the grip portion <NUM> (of the tool body <NUM>). This allows the electric tool <NUM> to be used with a battery pack <NUM> with any desired voltage value or capacity attached to the grip portion <NUM>.

Furthermore, each of the plurality of all-solid-state batteries <NUM> has a rectangular sheet shape. As shown in <FIG>, the longitudinal axis of the plurality of all-solid-state batteries <NUM> is aligned with the orientation of the tool <NUM> attached to the tool attachment member <NUM> (i.e., the forward/backward direction in this embodiment). That is to say, the plurality of all-solid-state batteries <NUM> are arranged such that their longer side 35A is aligned with the X-axis direction and their shorter side 35B is aligned with the Y-axis direction. This enables reducing, compared to a situation where the plurality of all-solid-state batteries <NUM> are arranged such that their longer side 35A is perpendicular to the orientation of the tool <NUM> (i.e., the forward/backward direction), the width of the battery pack <NUM> as measured perpendicularly to the orientation of the tool <NUM> with the tool <NUM> pointed at the workpiece.

The electric tool <NUM> according to this embodiment is made usable by attaching the battery pack <NUM> to the battery attachment portion <NUM> of the grip portion <NUM>. Note that a tool <NUM> of the type suitable for the machining work that the user <NUM> is going to do is attached by the user <NUM> to the tool attachment member <NUM>.

When the user <NUM> has not pulled the trigger <NUM> yet, the control unit <NUM> keeps the driving unit <NUM> deactivated and does not rotate the tool attachment member <NUM>.

On the other hand, when the user <NUM> pulls the trigger <NUM>, the control unit <NUM> starts driving the driving unit <NUM> in rotation, thereby turning the tool <NUM> attached to the tool attachment member <NUM>. At this time, the control unit <NUM> controls, based on the manipulative variable of the operation of pulling the trigger <NUM>, the rotational velocity of the driving unit <NUM> (i.e., the rotational velocity of the tool attachment member <NUM>). This allows the user <NUM> to have any desired type of machining work done using the electric tool <NUM> by performing the operation of pulling the trigger <NUM>.

In the exemplary embodiment described above, the respective weights of the body portion <NUM> and the battery pack <NUM> are set such that the center of mass of the electric tool <NUM> is located in the gripping part <NUM>. Alternatively, the respective weights of the body portion <NUM> and the battery pack <NUM> may be set such that the battery pack <NUM> is heavier than the body portion <NUM>.

If the battery pack <NUM> is heavier than the body portion <NUM>, the center of mass of the electric tool <NUM> is located in a part, proximate to the battery pack <NUM>, of the grip portion <NUM>. The suspension fitting <NUM> is attached to the end portion <NUM>, to which the battery pack <NUM> is attached, of the grip portion <NUM>, thus allowing the electric tool <NUM> to be suspended from a position close to the center of mass of the electric tool <NUM>. This may reduce, while the user <NUM> is moving or doing some type of work with the electric tool <NUM> suspended from the working belt <NUM>, the chances of the electric tool <NUM> being shaken significantly around the suspension fitting <NUM>. This may reduce the chances of the electric tool <NUM> suspended obstructing the user's <NUM> movement or doing some other type of work.

In addition, even if the suspension fitting <NUM> comes loose from the working belt <NUM> to let the electric tool <NUM> fall while the electric tool <NUM> is suspended from the working belt <NUM> as shown in <FIG>, the electric tool <NUM> will hit the ground with the battery pack <NUM>, which is heavier than the body portion <NUM>, facing down. That is to say, the battery pack <NUM> of the electric tool <NUM> will hit the ground earlier than the body portion <NUM> thereof, thus allowing the battery pack <NUM> to receive the impact caused by the fall. This may reduce the impact applied to the driving unit <NUM> and the transmission unit <NUM>. Consequently, this achieves the advantage of reducing the frequency of occurrence of failures caused in the driving unit <NUM> and the transmission unit <NUM>.

In this case, the battery pack <NUM> may be made heavier than the body portion <NUM> by increasing the weight of the power storage unit <NUM> with the number of the all-solid-state batteries <NUM> included in the power storage unit <NUM> increased, for example. Alternatively, the battery pack <NUM> may be made heavier than the body portion <NUM> by reducing the weight of the body portion <NUM> with either the driving unit <NUM> or the transmission unit <NUM> made lighter in weight. In this embodiment (as well as its variations), the power storage unit <NUM> is made up of all-solid-state batteries <NUM>, each of which is lighter in weight than a liquid battery such as a lithium-ion battery. The battery pack <NUM> may be made heavier than the body portion <NUM> by either increasing the number of the all-solid-state batteries <NUM> or increasing the size of each of the all-solid-state batteries <NUM>.

In the exemplary embodiment and variations described above, the electric tool <NUM> includes the power storage unit <NUM> in which the plurality of all-solid-state batteries <NUM> are stacked one on top of another. Optionally, the plurality of all-solid-state batteries <NUM> may be kept in close contact with each other by applying pressure to those all-solid-state batteries <NUM> that are stacked one on top of another. Note that the plurality of all-solid-state batteries <NUM> do not have to be kept in contact with each other with pressure applied thereto but may be just stacked one on top of another.

Optionally, in the exemplary embodiment and variations described above, a buffer member made of synthetic rubber, for example, may be provided between the inner surface of the battery case <NUM>, 31A and the power storage unit <NUM> to reduce the impact applied to the power storage unit <NUM>.

Furthermore, in the exemplary embodiment and variations described above, the battery pack <NUM> may or may not be one of the constituent elements of the electric tool <NUM>.

According to the claimed invention, the electric tool (<NUM>) may stand by itself in its entirety with a bottom surface (<NUM>) of the battery pack (<NUM>) put on a mounting surface (<NUM>). Thus, putting the electric tool (<NUM>) violently onto the mounting surface (<NUM>) with the battery pack (<NUM>) facing down could apply impact to the battery pack (<NUM>). In this configuration, the battery pack (<NUM>) includes all-solid-state batteries (<NUM>) with higher impact resistance than a liquid battery such as a lithium-ion battery. This may reduce, even if impact is applied to the battery pack (<NUM>), the chances of causing abnormality to the battery pack (<NUM>). Thus, an electric tool (<NUM>) that may reduce the chances of causing inconveniences to the battery pack (<NUM>) may be provided.

In an electric tool (<NUM>) according to a further aspect, which may be implemented in conjunction with the first aspect, a direction in which the plurality of all-solid-state batteries (<NUM>) are stacked one on top of another is aligned with a line segment that connects together the first end portion (<NUM>) and the second end portion (<NUM>), interposing the gripping part (<NUM>), of the grip portion (<NUM>).

This aspect reduces, even if external force is applied to the battery pack (<NUM>) in the direction aligned with the line segment that connects together the first and second end portions (<NUM>, <NUM>) of the grip portion (<NUM>), the chances of causing peeling and/or misalignment between the respective layers of the plurality of all-solid-state batteries (<NUM>), thus reducing inconveniences to be caused in the battery pack (<NUM>).

In an electric tool (<NUM>) according to a further aspect, which may be implemented in conjunction with the first aspect, a direction in which the plurality of all-solid-state batteries (<NUM>) are stacked one on top of another is aligned with a direction perpendicular to the bottom surface (<NUM>) of the battery pack (<NUM>).

This aspect reduces, even if external force is applied to the battery pack (<NUM>) in the direction perpendicular to the bottom surface (<NUM>) of the battery pack (<NUM>), the chances of causing peeling and/or misalignment between the respective layers of the plurality of all-solid-state batteries (<NUM>), thus reducing inconveniences to be caused in the battery pack (<NUM>). In addition, this also reduces, even if the electric tool (<NUM>) is put violently on the mounting surface (<NUM>) with the battery pack (<NUM>) facing down, the chances of the impact applied to the battery pack (<NUM>) causing abnormality to the battery pack (<NUM>). Thus, an electric tool (<NUM>) that may reduce the chances of causing inconveniences to the battery pack (<NUM>) may be provided.

In an electric tool (<NUM>) according to a further aspect, which may be implemented in conjunction with any one of the first to third aspects, each of the plurality of all-solid-state batteries (<NUM>) has a rectangular sheet shape. A longitudinal axis of the plurality of all-solid-state batteries (<NUM>) is aligned with an orientation of the tool (<NUM>) attached to the tool attachment member (<NUM>).

This aspect may reduce the width of the battery pack (<NUM>) as measured perpendicularly to the orientation of the tool (<NUM>) pointed at the workpiece, compared to a situation where the latitudinal axis of the plurality of all-solid-state batteries (<NUM>) is aligned with the orientation of the tool (<NUM>).

In an electric tool (<NUM>) according to a further aspect, which may be implemented in conjunction with any one of the first to fourth aspects, multiple different types of battery packs (<NUM>), which have mutually different voltage values and/or capacities and one of which is battery pack (<NUM>), are provided. One battery pack (<NUM>) selected from the multiple different types of battery packs (<NUM>) is attached to the grip portion (<NUM>).

This aspect allows a battery pack (<NUM>) with a desired voltage value or capacity to be selectively used.

In an electric tool (<NUM>) according to a further aspect, which may be implemented in conjunction with any one of the first to fifth aspects, the battery pack (<NUM>) is attachable to, and removable from, the grip portion (<NUM>).

This aspect allows the battery pack (<NUM>) to be attached to the grip portion (<NUM>) provided for the body portion (<NUM>).

In an electric tool (<NUM>) according to a further aspect, which may be implemented in conjunction with the sixth aspect, the battery pack (<NUM>) is attached to the grip portion (<NUM>) by sliding the battery pack (<NUM>) in a slide direction aligned with the bottom surface (<NUM>) of the battery pack (<NUM>).

According to this aspect, when the user (<NUM>) holds the grip portion (<NUM>) such that the longitudinal axis of the grip portion (<NUM>) is aligned with the upward/downward direction, the slide direction of the battery pack (<NUM>) will be aligned with the direction perpendicular to the upward/downward direction (that is the direction of gravity). This reduces the risk of the gravitational force applied to the battery pack (<NUM>) causing the battery pack (<NUM>) to move in the slide direction, thus reducing the chances of the battery pack (<NUM>) disengaging itself from the grip portion (<NUM>).

A battery pack (<NUM>) according to a further aspect is designed for use in the electric tool (<NUM>) according to any one of the first to seventh aspects. The battery pack (<NUM>) includes a plurality of all-solid-state batteries (<NUM>), each of the plurality of all-solid-state batteries (<NUM>) being formed in a sheet shape, and the plurality of all-solid-state batteries (<NUM>) are stacked one on top of another. The battery pack (<NUM>) includes a battery case (<NUM>) to house the plurality of all-solid-state batteries (<NUM>) therein.

According to this aspect, the electric tool (<NUM>) in its entirety may stand by itself with a bottom surface (<NUM>) of the battery pack (<NUM>) put on a mounting surface (<NUM>). Thus, putting the electric tool (<NUM>) violently onto the mounting surface (<NUM>) with the battery pack (<NUM>) facing down could apply impact to the battery pack (<NUM>). In this configuration, the battery pack (<NUM>) includes all-solid-state batteries (<NUM>) with higher impact resistance than a liquid battery such as a lithium-ion battery. This may reduce, even if impact is applied to the battery pack (<NUM>), the chances of causing abnormality to the battery pack (<NUM>). Thus, a battery pack (<NUM>) that may reduce the chances of causing inconveniences to itself may be provided.

Claim 1:
An electric tool (<NUM>) comprising:
a body portion (<NUM>) including: a tool attachment member (<NUM>) to which a tool (<NUM>) is attached; a driving unit (<NUM>) configured to drive the tool (<NUM>); and a transmission unit (<NUM>) configured to transmit driving force of the driving unit (<NUM>) to the tool (<NUM>);
a grip portion (<NUM>) including a gripping part designed to be held by a user with his or her hand; and
a battery pack (<NUM>) configured to supply power to the driving unit (<NUM>),
characterized in that:
the grip portion (<NUM>) includes: a first end portion (<NUM>); and a second end portion (<NUM>) located opposite from the first end portion (<NUM>) with respect to the gripping part (<NUM>), the body portion (<NUM>) being connected to the first end portion (<NUM>), the battery pack (<NUM>) being attached to the second end portion (<NUM>),
the electric tool (<NUM>) in its entirety, including the body portion (<NUM>), the grip portion (<NUM>), and the battery pack (<NUM>), is configured to stand by itself with a bottom surface (<NUM>), opposite from the grip portion (<NUM>), of the battery pack (<NUM>) put on a mounting surface, characterised in that
the battery pack (<NUM>) includes a plurality of all-solid-state batteries (<NUM>), each of the plurality of all-solid-state batteries (<NUM>) being formed in a sheet shape, and
the plurality of all-solid-state batteries (<NUM>) are stacked one on top of another, and wherein
a direction in which the plurality of all-solid-state batteries (<NUM>) are stacked one on top of another is aligned with a direction perpendicular to the bottom surface (<NUM>) of the battery pack (<NUM>).