Patent Description:
A body of an electric machine tool such as a chain saw and a brush cutter has a motor receiving chamber, in which a motor has been disposed, and a battery receiving chamber, in which a battery is to be disposed. According to such electrical machine tool, a battery is disposed in a battery receiving chamber and the battery supplies electrical power to a motor to drive a work tool such as a saw chain and a rotating blade.

According to the conventional electric chain saw, a battery receiving chamber opens through an upper face of a body and may be configured to cool a motor in a motor receiving chamber and a control board by making air flow from a battery receiving chamber into the motor receiving chamber (e.g., <CIT>).

<CIT> discloses an electric machine tool of the type described above.

The Japanese patent application <CIT> discloses a power tool according to the preamble of claim <NUM> with a cooling structure. The power tool includes a fan mounted on a rotating shaft of the motor to cool the motor. The housing of the power tool comprises a body portion for storing the motor, a handle extending downward from the body portion, and a battery retainer at a front end of the handle. An air inlet/outlet is provided in the battery retainer to cool the control circuit by generating air flows in the handle. The battery for the power tool is positioned outside of the housing. No filtering of the air flows takes place.

According to the conventional chain saw described above, chips and dust particles occurring when cutting are likely to enter into the motor receiving chamber from the battery receiving chamber. The remaining of the dust particles in the motor receiving chamber leads to reduction in the cooling efficiency of the motor as well as of the control board, and reduction in the driving efficiency of the motor. Thus, according to the conventional chain saw, the interior of a body must be cleaned frequently, which makes the maintenance of the conventional chain saw difficult.

It is an object of the invention to provide an electric machine tool which is capable of preventing dust particles from coming into a motor receiving chamber and reduce the frequency of the maintenance of the electric machine tool.

The electric machine tool of the invention includes: a body, to which a work tool is attached; a motor for driving the work tool; a battery for supplying electrical power to the motor; and, the body having a motor receiving chamber, in which the motor is disposed, an air discharging means to discharge the air in the motor receiving chamber, a battery receiving chamber opening through an outer surface of the body, and a communication path, through which the battery receiving chamber is in communication with the motor receiving chamber. A first air inlet opening is formed between the inner edge of an opening of the battery receiving chamber and the outer periphery of the battery disposed in the battery receiving chamber. An inflow port of the communication path opens to an inner side surface of the battery receiving chamber. An air filter is fitted over the inflow port.

According to the electric machine tool of the invention, when air flows through the air filter into the communication path, the dust particles in the air are filtered off by the air filter. In this way, dust particles are unlikely to enter into the motor receiving chamber. Thus, according to the electric machine tool of the invention, dust particles are unlikely to remain in the motor receiving chamber. This can extend time between the cleans of the interior of a body and can reduce the frequency of the maintenance of the electric machine tool. The air filter is disposed on an inner side surface of the battery receiving chamber according to the electric machine tool of the invention. Thus, the attachment/detachment of and the clean of the air filter can be simply conducted from the outside of the body by removing the battery from the battery receiving chamber.

The invention will now be described with reference of the drawings wherein:.

Embodiments of the invention will be explained in detail appropriately referring to the drawings. The embodiments are explained with an example configuration of a chain saw cutting woods, boards, etc, to which the present invention is applied.

As <FIG> shows, a chain saw <NUM> has a body <NUM> and a cutter <NUM> attached to the body <NUM>. As <FIG> shows, the chain saw <NUM> has a motor <NUM> for driving the cutter <NUM>, a control board <NUM> for controlling operation of the motor <NUM>, and a battery <NUM> for supplying electrical power to the motor <NUM>.

As <FIG> shows, the body <NUM> has a box body housing <NUM> made of a resin and an upper cover <NUM> made of a resin covering a top portion of the body housing <NUM>. As <FIG> shows, a motor receiving chamber <NUM> and a battery receiving chamber <NUM> are formed in the body housing <NUM>.

The motor receiving chamber <NUM> is formed in a front area of the body housing <NUM> as <FIG> shows. The body housing <NUM> has an interior housing space in which the motor receiving chamber <NUM> is formed. Driving mechanism devices such as the motor <NUM>, the control board <NUM>, and a blower fan <NUM> are disposed in the motor receiving chamber <NUM>.

The motor <NUM> may be any type of an electric motor which has been known has a hollow motor housing <NUM>, into which a cylindrical yoke 30a is inserted, an output shaft <NUM> engaged with the yoke 30a, and a sensor board 30b for detecting the rotation of the yoke 30a.

An insertion hole 31a, through which the yoke 30a is inserted, is formed through the right side surface of the motor housing <NUM> as <FIG> shows. A gap is formed between the inner edge of the insertion hole 31a and the outer periphery of the yoke 30a.

An outflow port 31b opens through a bottom portion of the motor housing <NUM>. A cylindrical air flow path <NUM>, through which the outflow port 31b is in communication with an air outlet opening 11b, is formed at the bottom of the body housing <NUM>. One end of the air flow path <NUM> communicates with the outflow port 31b and the other end communicates with the air outlet opening 11b, which opens through the right side surface of the body housing <NUM> as <FIG> shows.

A stator (not shown in the drawings) is disposed in the yoke 30a. When a coil of the stator is energized, the yoke rotates around the axis of the output shaft. A base end portion of the output shaft <NUM> engages with the yoke 30a and a leading end portion of the output shaft <NUM> projects outwardly through a right side wall 11a of the body housing <NUM> as <FIG> shows.

The sensor board 30b, which engages with the stator, is fixed relative to the motor <NUM>. The sensor board 30b has a circular shape with a center hole. The yoke 30a is concentrically inserted through the center hole of the sensor board 30b.

The blower fan <NUM> is disposed in the motor housing <NUM>. The blower fan <NUM> is secured to the yoke 30a. Thus, the blower fan <NUM> rotates in conjunction with the rotation of the yoke 30a. The blower fan <NUM>, the outflow port 31b, the air flow path <NUM>, and the air outlet opening 11b constitute air discharging means to discharge the air in the motor receiving chamber <NUM> to the outside of the body housing <NUM>. The blower fan <NUM> blows the air in the motor housing <NUM> when rotating and then make the air flow via the outflow port 31b through the air flow path <NUM> via the air outlet opening 11b to the outside of the body housing <NUM>. Meanwhile, the air in the motor receiving chamber <NUM> flows into the motor housing <NUM> through the insertion hole 31a. In this way, the air in the motor receiving chamber <NUM> is discharged through the motor housing <NUM> to the outside of the body housing <NUM>.

A drive gear <NUM> engages with the leading end portion of the output shaft <NUM>. The drive gear <NUM> is disposed adjacent to the right side wall 11a of the body housing <NUM> as <FIG> shows.

The control board <NUM> is an electrical circuit board attached onto a heat dissipation member made of metal. The control board <NUM> is electrically connected to the motor <NUM>. The control board <NUM> is disposed in a rear area of the motor receiving chamber <NUM> as <FIG> shows.

The battery receiving chamber <NUM> is formed in a rear area of the body housing <NUM> as <FIG> shows. As <FIG> shows, the battery receiving chamber <NUM> is a substantially rectangular receptacle and opens through an upper face of the body housing <NUM>.

The battery receiving chamber <NUM> receives the battery <NUM> (as referred to <FIG>). The battery <NUM> may be any type of a battery which has been known and comprises a rectangular housing and a secondary battery (e.g., a lithium ion battery) disposed in the rectangular housing.

As <FIG> shows, a gap is formed between the inner edge of an opening 16a of the battery receiving chamber <NUM> and the outer periphery of an upper portion of the battery <NUM> disposed in the battery receiving chamber <NUM>. Thus, this gap functions as a first air inlet opening <NUM>. According to the embodiment, as <FIG> shows the first air inlet opening <NUM> has a circular shape and extends along the outer periphery of the upper portion of the battery <NUM>.

A connection terminal (not shown in the drawings), which is electrically connected to the control board <NUM> shown in <FIG>, is provided at the bottom of the motor receiving chamber <NUM>. A connection terminal of the battery <NUM> is connected to the connection terminal at the bottom of the battery receiving chamber <NUM>, whereby the battery <NUM> supplies electrical power to the control board <NUM> and the motor <NUM>.

An ejecting mechanism (not shown in the drawings) is provided at the bottom of the battery receiving chamber <NUM> to eject the battery <NUM> from the battery receiving chamber <NUM>. With the battery <NUM> held in the battery receiving chamber <NUM> as shown in <FIG>, the ejecting mechanism is actuated to push the battery <NUM> upward from the battery receiving chamber <NUM> by operating a lever <NUM> provided at the top of the battery <NUM>.

As <FIG> shows, two right and left second air inlet openings <NUM> are formed through right and left bottom portions of the battery receiving chamber <NUM> and open through right and left lower portions in a rear area of the body housing <NUM>. According to this embodiment, the total opening area of both of the second air inlet openings <NUM> is configured to be larger than that of the first air inlet opening <NUM>.

Right and left bottom portions of the battery <NUM>, which is disposed in the battery receiving chamber <NUM>, are exposed to the outside through both of the second air inlet openings <NUM> (as referred to <FIG>).

As <FIG> shows, a top portion of the body housing <NUM> is covered by an upper cover <NUM>. The upper cover <NUM> is fixed to the body housing <NUM> by one bolt B (as referred to <FIG>). The upper cover <NUM> has an opening 12a formed to be in communication with the opening 16a of the battery receiving chamber <NUM>.

The cutter <NUM> is attached to the right side of the body housing <NUM> as <FIG> shows. The cutter <NUM> configured as a work tool for cutting has a guide bar <NUM> and a saw chain <NUM>. The guide bar <NUM> is a plate-like member extending longitudinally and a rear end portion of the guide bar <NUM> is attached to the right side of the body housing <NUM>. The saw chain <NUM> is wound along the periphery of the guide bar <NUM>. As <FIG> shows, a rear end portion of the saw chain <NUM> engages with the drive gear <NUM>.

The saw chain <NUM> is driven along the outer periphery of the guide bar <NUM> when the motor <NUM> is driven to rotate the drive gear <NUM> (as referred to <FIG>). A side cover <NUM> is attached to an outer surface of the right side wall 11a of the body housing <NUM> to cover the drive gear <NUM> and a rear end portion of the cutter <NUM>.

As <FIG> shows, a front handle <NUM> as well as a rear handle <NUM> is attached to the body housing <NUM>. The front handle <NUM>, a gripping portion, extends around the body housing <NUM> and is formed by bending a cylindrical member. The rear handle <NUM> engages with a rear portion of the body housing <NUM> as <FIG> shows. A trigger lever 62a is disposed on the rear handle <NUM> and is capable of increasing/decreasing the speed of the rotation of the saw chain <NUM> when gripping the rear handle <NUM>.

An operator typically grips the front handle <NUM> by one hand and the rear handle by the other hand when cutting an object such as woods and boards. Then the object can be cut by operating the trigger lever 62a disposed on the rear handle <NUM> to rotate the saw chain <NUM>.

Because the cutter <NUM> is attached to the right side of the body <NUM> according to the chain saw <NUM> of this embodiment, an operator is at the left side of the body <NUM> when using the chain saw <NUM>.

The cooling structure of the chain saw <NUM> of this embodiment will be explained. As <FIG> shows, a communication path <NUM>, through which the battery receiving chamber <NUM> is in communication with the motor receiving chamber <NUM>, is formed in the body housing <NUM>. Air is drawn into the motor receiving chamber <NUM> from the battery receiving chamber <NUM> through the communication path <NUM>.

As <FIG> shows, the communication path <NUM> is formed in a left area of the body housing <NUM>, and extends longitudinally relative to the left edge of a partition wall 11c between the motor receiving chamber <NUM> and the battery receiving chamber <NUM>. An inflow port 17a of the communication path <NUM> opens to a left side surface 16c of the battery receiving chamber <NUM> as <FIG> shows.

An air filter <NUM> is fitted over the inflow port 17a of the communication path <NUM>. The air filter <NUM> comprises a tabular frame body <NUM> and a nonwoven fabric <NUM> held by the tabular frame body <NUM> (as referred to <FIG>). The inflow port 17a is closed by the air filter <NUM>.

A front edge portion of the frame body <NUM> of the air filter <NUM> is attached to an attachment groove 11d formed on an end portion of the partition wall 11c as <FIG> shows. A rear edge portion of the frame body <NUM> has a hook <NUM> projecting outwardly to the left as <FIG> shows. The hook <NUM> is inserted through an attachment hole 11f formed through a left wall 11e of the body housing <NUM>. The leading end portion of the hook <NUM> engages with an outer surface of the left wall 11e as <FIG> shows. As <FIG> shows, the air filter <NUM> according to this embodiment has upper and lower hooks <NUM>.

As <FIG> shows, a surface 70a of the air filter <NUM> extends in the direction of a predetermined angle θ relative to the vertical direction. The surface 70a of the air filter <NUM> comes inward as the surface 70a of the air filter <NUM> extends upward. The surface 70a of the air filter <NUM> thus extends downwardly obliquely. According to the embodiment, the predetermined angle θ of the surface 70a of the air filter <NUM> relative to the vertical direction is set to <NUM> degrees.

As <FIG> shows, the left second air inlet opening <NUM> is formed below the air filter <NUM>. Thus, the air inlet opening <NUM> is formed below the surface 70a of the air filter <NUM>.

As <FIG> shows, according to the chain saw <NUM> of this embodiment, the air in the motor receiving chamber <NUM> is discharged through the motor housing <NUM> to the outside of the body housing <NUM> when the motor <NUM> is driven to rotate the blower fan <NUM>. The air in the motor receiving chamber <NUM> is discharged by the air discharging means (the blower fan <NUM>, the outflow port 31b, the air flow path <NUM>, and the air outlet opening 11b), whereby the air flows into the motor receiving chamber <NUM> through the communication path <NUM> from the battery receiving chamber <NUM>.

As <FIG> shows, air flows into the battery receiving chamber <NUM> through the first air inlet opening <NUM> and the second air inlet openings <NUM> from the outside of the chain saw <NUM>, and then flows into the communication path <NUM>. As <FIG> shows, when air flows into the communication path <NUM> through the air filter <NUM>, the dust particles in the air are filtered off by the air filter <NUM>. The control board <NUM> and the sensor board 30b are cooled by the air which flows into the motor receiving chamber <NUM> from the communication path <NUM>. The interior of the motor <NUM> is then cooled by the air which flows into the motor housing <NUM> from the motor receiving chamber <NUM>, which can improve the cooling efficiency of the motor <NUM>.

The air in the motor receiving chamber <NUM> is discharged from a left area in the body housing <NUM> through the air flow path <NUM> to the outside (the right side) adjacent to the work tool <NUM> as <FIG> shows. The air in the motor receiving chamber <NUM> can be simply discharged because an operator is at the left side of the body housing <NUM> according to the chain saw <NUM> of this embodiment. The air in the motor receiving chamber <NUM> is discharged through a right side surface of the body housing <NUM>, which also enables an operator at the left side of the body housing <NUM> to keep away from chips and dust particles occurring when cutting.

When the air filter <NUM> is to be removed from the body housing <NUM>, the bolt B is unscrewed off from the body housing <NUM> after removing the battery <NUM> from the battery receiving chamber <NUM> as <FIG> shows. Next, when the upper cover <NUM> is removed from the body housing <NUM>, leading end portions of the two hooks <NUM> are exposed adjacent to an outer surface of the left wall 11e of the body housing <NUM>.

Subsequently, as <FIG> shows, the leading end portions of the hooks <NUM> are pushed through the attachment hole 11f. In this way, as <FIG> shows, the hooks can be detached from the left wall 11e of the body housing <NUM>. Further, when a rear edge portion of the air filter <NUM> is moved inward in the battery receiving chamber <NUM> and the air filter <NUM> is then tilted relative to the left wall 11e, a front edge portion of the air filter <NUM> can be detached from the attachment groove 11d. In this way, the air filter <NUM>, which has been detached from the attachment groove 11d, can be removed out of the battery receiving chamber <NUM> through the opening 16a as <FIG> shows.

The chain saw <NUM> (an electric machine tool) described above includes the body <NUM>, to which the cutter <NUM> (a work tool) is attached, the motor <NUM> for driving the cutter <NUM>, and the battery <NUM> for supplying electrical power to the motor <NUM>. In the body <NUM>, the motor receiving chamber <NUM>, in which the motor <NUM> is disposed, the battery receiving chamber <NUM> opening through an outer surface of the body <NUM>, and the communication path <NUM>, through which the battery receiving chamber <NUM> is in communication with the motor receiving chamber <NUM>, are formed. The first air inlet opening <NUM> is formed between the inner edge of the opening 16a of the battery receiving chamber <NUM> and the outer periphery of the battery <NUM> disposed in the battery receiving chamber <NUM>. The inflow port 17a of the communication path <NUM> opens to the left side surface 16c of the battery receiving chamber <NUM>. The air filter <NUM> is fitted over the inflow port 17a.

According to the chain saw <NUM> of this embodiment, when air flows into the communication path <NUM> through the air filter <NUM>, the dust particles in the air are filtered off by the air filter <NUM>. Thus, according to the chain saw <NUM> of this embodiment, dust particles are unlikely to enter into the motor receiving chamber <NUM>. As a result, according to the chain saw <NUM> of this embodiment, dust particles are unlikely to remain in the motor receiving chamber <NUM>. This can extend time between the cleans of the interior of the body <NUM> and can reduce the frequency of the maintenance of the chain saw <NUM>.

According to the chain saw <NUM> of this embodiment, the air filter <NUM> is disposed on the left side surface 16c of the battery receiving chamber <NUM>. Thus, the attachment/detachment and the clean of the air filter <NUM> can be simply conducted from the outside of the body <NUM> through the opening 16a of the battery receiving chamber <NUM> by removing the battery <NUM> from the battery receiving chamber <NUM>.

According to the chain saw <NUM> of this embodiment, as <FIG> shows, the surface 70a of the air filter <NUM> extends in the direction of the predetermined angle θ relative to the vertical direction. Thus, dust particles are unlikely to settle on the surface 70a of the air filter <NUM>. If the dust particles settle on the surface 70a of the air filter <NUM>, the dust particles easily fall off by impact and vibration which are similar to those that occur when the chain saw <NUM> is placed on the ground. Thus, the air filter <NUM> is unlikely to become dirty and this can extend time between the cleans of the air filter <NUM> and time between the replacements of the air filter <NUM>.

The body <NUM> of the chain saw <NUM> according to this embodiment has the second air inlet openings <NUM>, which are formed through the right and left bottom portions of the battery receiving chamber <NUM> and open through an outer surface of the body <NUM>. Because of this configuration, air flows into the battery receiving chamber <NUM> from the first air inlet opening <NUM> and the second air inlet openings <NUM>. This ensures that a sufficient amount of air flows into the battery receiving chamber <NUM> to cool the motor <NUM> and the control board <NUM> as <FIG> shows.

According to the chain saw <NUM> of this embodiment, as <FIG> shows, both of the second air inlet openings <NUM> are formed and the total opening area of both of the second air inlet openings <NUM> is configured to be larger than that of the first air inlet opening <NUM>.

Because of this configuration, an amount of the air which flows into the battery receiving chamber <NUM> from both of the second air inlet openings <NUM> is greater than that which flows into the battery receiving chamber <NUM> from the first air inlet opening <NUM>. This can lead to a low flow speed of the air into the battery receiving chamber <NUM> from the first air inlet opening <NUM> so that the number of the dust particles which flow into the battery receiving chamber <NUM> through the first air inlet opening <NUM> can be reduced. Because both of the second air inlet openings <NUM> are formed through the right and left bottom portions of the battery receiving chamber <NUM>, dust particles are unlikely to enter into the battery receiving chamber <NUM> from under the body <NUM> through both of the second air inlet openings <NUM>. Thus, according to the chain saw <NUM> of this embodiment, as <FIG> shows, dust particles can be unlikely to enter into the battery receiving chamber <NUM> and a necessary, sufficient amount of air can flow into the battery receiving chamber <NUM> to cool the motor <NUM> and the control board <NUM>.

According to the chain saw <NUM> of this embodiment, as <FIG> shows, the dust particles which enter into the battery receiving chamber <NUM> are discharged to the outside through the second air inlet openings <NUM> formed through the right and left bottom portions of the battery receiving chamber <NUM>. As a result, dust particles are unlikely to remain in the battery receiving chamber <NUM>. As <FIG> shows, the left second air inlet opening <NUM> is formed below the air filter <NUM> and thus the dust particles which fall off from the air filter <NUM> are also discharged to the outside through the left second air inlet opening <NUM>.

According to the chain saw <NUM> of this embodiment, when the battery <NUM> is disposed in the battery receiving chamber <NUM>, the right and left bottom portions of the battery <NUM> are exposed through both of the second air inlet openings <NUM> formed through the right and left bottom portions of the battery receiving chamber <NUM>. Thus, even if the ejecting mechanism for the battery <NUM> does not work, the battery can be removed out of the battery receiving chamber <NUM> by inserting a hand into the battery receiving chamber <NUM> from the second air inlet opening <NUM> and then pushing a bottom portion of the battery <NUM> upward.

According to the chain saw <NUM> of this embodiment, as <FIG> shows, the cutter <NUM> (a work tool) is attached to the right side (one side) of the body <NUM>. In this configuration, an operator is typically at the left side of the body <NUM>. As a result, dust particles become unlikely to enter into the battery receiving chamber <NUM> through a left area of the first air inlet opening <NUM> and the left second air inlet opening <NUM>. According to the chain saw <NUM> of this embodiment, the inflow port 17a of the communication path <NUM> is formed inside the left side surface 16c (the opposite side) of the battery receiving chamber <NUM> of the body <NUM>. As a result, dust particles are unlikely to settle on the air filter <NUM> fitted over the inflow port 17a.

Although the embodiments of this invention have been described above, the invention is not limited to the embodiments and changes as well as modifications can be appropriately made hereto without departing from the spirit and scope of the present disclosure. According to the chain saw <NUM> of this embodiment, as <FIG> shows, the communication path <NUM> is formed and the air filter <NUM> is disposed in a left area of the body <NUM>, which is however not limited. The communication path <NUM> may be formed and the air filter <NUM> may be disposed in a front, a rear, or a right area of the body <NUM>.

According to the chain saw <NUM> of this embodiment, as <FIG> shows, the surface 70a of the air filter <NUM> is disposed so as to extend downwardly obliquely relative to the vertical direction. The shape and the attachment state of the air filter <NUM> is however not limited to this and the surface 70a of the air filter <NUM> may, for example, extend in the horizontal direction.

According to the chain saw <NUM> of this embodiment, both of the second air inlet openings <NUM> are formed through the right and left bottom portions of the battery receiving chamber <NUM> but the number and the shapes of the second air inlet openings <NUM> are not limited to this. According to the chain saw <NUM> of this embodiment, as <FIG> shows, the first air inlet opening <NUM> has a circular shape and extends along the entire outer periphery of the upper portion of the battery <NUM>. The first air inlet opening <NUM> may, however, extend along a part of the entire outer periphery of the upper portion of the battery <NUM>.

Claim 1:
An electric machine tool (<NUM>) comprising:
a body (<NUM>), which a work tool (<NUM>) is attached to and which has a body housing (<NUM>);
a motor (<NUM>) for driving the work tool (<NUM>);
a battery (<NUM>) for supplying electrical power to the motor (<NUM>);
a motor receiving chamber (<NUM>) of the body (<NUM>), in which the motor (<NUM>) is disposed and an air discharging means (<NUM>, 31b, <NUM>, 11b) to discharge the air in the motor receiving chamber (<NUM>);
a battery receiving chamber (<NUM>) of the body (<NUM>); and
a communication path (<NUM>) of the body (<NUM>), through which the battery receiving chamber (<NUM>) is in communication with the motor receiving chamber (<NUM>);
characterized by:
the battery receiving chamber (<NUM>) of the body (<NUM>), which the battery (<NUM>) is disposed within and which has an opening (16a) extending through the body housing (<NUM>) to the outside;
an air outlet opening (11b) of the body (<NUM>), which is formed through the body housing (<NUM>);
a first air inlet opening (<NUM>) defined by an inner edge of the opening (16a) of the battery receiving chamber (<NUM>) and an outer periphery of the battery (<NUM>) disposed in the battery receiving chamber (<NUM>);
an inflow port (17a) of the communication path (<NUM>) opens to an inner side surface (16c) of the battery receiving chamber (<NUM>), and
an air filter (<NUM>) is fitted over the inflow port (17a).