Patent Description:
Hand-held work tools for cutting and/or abrading hard materials such as concrete and stone comprise powerful motors in order to provide the required power for processing the hard materials. These motors generate a substantial amount of heat and therefore need to be cooled in order to prevent overheating. Electrical work tools generate heat by the electrical motor, and also by the battery and control electronics. There is a need for efficient methods of cooling such work tools. A few examples are known from <CIT>, <CIT>, <CIT> and <CIT>.

The work tools also normally generate vibration which may be harmful or at least cause discomfort to an operator of the tool. It is desired to protect the operator from prolonged exposure to strong vibration.

The environments in which these types of tools are used are often harsh. The work tools are exposed to water, dust, debris, and slurry, which may affect tool performance negatively. For instance, slurry may accumulate in the work tool interior where it eventually causes tool failure. It is desired to prevent accumulation of dust and slurry in the work tool interior.

Ease of operation is especially important for work tools used on construction sites. For electrical work tools, it is desirable that in-field battery change can be made in an efficient and convenient manner where the battery is easy to insert in the work tool, where the battery is snugly held in the work tool, and where the battery is easily released from the work tool.

To summarize, there are challenges associated with hand-held work tools.

It is an object of the present disclosure to provide improved hand-held work tools which address the above-mentioned issues. This object is at least on part obtained by a hand-held work tool comprising a first part and a second part arranged vibrationally isolated from each other. The first part comprises an interface for holding a cutting tool and an electric motor arranged to drive the cutting tool. The electric motor is arranged to drive a fan configured to generate a flow of cooling air for cooling the electric motor. The second part comprises a battery compartment for holding an electrical storage device arranged to power the electric motor. A cooling air conduit is arranged to guide a portion of the flow of cooling air from the first part and into the second part for cooling the electrical storage device.

The main vibration generating parts of the work tool are comprised in the first part. Thus, by vibrationally isolating the first part from the second part, the amount of vibration propagating to the second part is significantly reduced. The second part may, e.g., comprise front and rear handles which are then vibrationally isolated from the vibration sources in the first part. Since vibration is reduced, an operator may use to tool longer and with an increased comfortlevel. A single fan unit is used to cool both the electric motor and the electrical energy source. This is an advantage since there is no need for a second fan unit arranged in the second part. Efficient cooling of both the electric motor and of the electrical energy source is provided.

According to aspects, the fan comprises an axial fan portion arranged peripherally on the fan and a radial fan portion arranged centrally on the fan. The axial fan portion is arranged to generate the flow of cooling air for cooling the electric motor, and the radial fan portion is arranged to generate the portion of the flow of cooling air from the first part and into the second part for cooling the electrical storage device. This way the portion of cooling air guided into the second part is not first heated by the electric motor, which improves the cooling effect. Also, the radial fan is better when it comes to pushing air flows though the conduit to the second part, which may comprise bends and narrow sections.

The fan may be assembled in a fan housing comprising at least one opening arranged peripherally in the housing for receiving the flow of cooling air for cooling the electric motor, and a fan scroll arranged centrally in the housing for guiding the portion of the flow of cooling air from the first part and into the second part for cooling the electrical storage device. This way the portion of the flow of cooling air from the first part and into the second part is efficiently pushed into the second part, which improves the cooling effect.

According to some aspects, the portion of the flow of cooling air guided from the first part and into the second part passes via a bellows or other flexible air flow conduit arranged in-between the first and the second parts. The flexible air flow conduit provides a connection between the first part and the second part which is able to withstand vibration, and which does not forward significant level of vibration from the first part to the second part. Other possible flexible air flow conduits may, e.g., comprise rubber or plastic hoses, and jointed sectioned conduits able to flex in two or more directions.

According to some other aspects, the bellows comprises a poka-yoke feature comprising at least one protrusion configured to enter a corresponding recess formed in the first part and/or in the second part, thereby preventing erroneous assembly of the bellows with the first and second parts. The poka-yoke feature prevents erroneous assembly, leading to a more efficient and less error prone assembly process, which is an advantage.

According to some further aspects, the bellows or other flexible air flow conduit comprises at least one edge portion of increased thickness, wherein each edge portion is arranged to enter a corresponding groove formed in the first part or in the second part, thereby fixing the bellows in relation to the first or second part. This arrangement provides a secure attachment between the bellows and the work tool body and is also easily assembled.

According to aspects, the bellows is arranged with a shape that is symmetric about a symmetry plane parallel to an extension direction of the edge portions.

The symmetric shape simplifies assembly since the bellows need not be turned in any specific way before assembly.

According to aspects, the portion of the flow of cooling air from the first part and into the second part is arranged to pass a control unit of the hand-held work tool. This way the control unit is also cooled by the portion of the flow of cooling air, which is an advantage since there is no need for a separate cooling fan or the like for cooling the control unit. The control unit cooling may be further improved by arranging a cooling flange in connection to the control unit.

According to some aspects, the first part comprises a belt guard configured to enclose an interior space. A portion of the flow of cooling air is arranged to be guided into the interior space, thereby increasing an air pressure in the belt guard interior space above an ambient air pressure level.

This way water, dust, debris, and slurry is at least in part prevented from entering an interior of the work tool where it may accumulate to eventually cause work tool failure. It is an advantage that the build-up of dust and debris in the work tool interior is reduced.

According to some other aspects, the first part comprises a thermally conductive support arm arranged to support the circular cutting tool on a first end of the support arm, and to support the electric motor by a support surface at a second end of the support arm opposite to the first end, wherein the support arm comprises one or more cooling flanges arranged to conduct heat away from the electric motor via the support surface. The cooling flanges improve heat dissipation from the electric motor via the support arm, which is an advantage. The support surface improves a thermal coupling between the electric motor and the support arm, thereby improving heat dissipation from the electric motor, which is an advantage.

According to some further aspects, the support arm is arranged to enclose the electric motor at least partially. The support arm thereby protects the electric motor and also has the function of transporting heat away from the electric motor.

According to aspects, the support arm and the electric motor are at least partially integrally formed. This means that the support arm and the electric motor may share some parts. For instance, a part of the electric motor housing may be formed by the support arm material. This part may, e.g., be a motor gable.

According to aspects, at least <NUM>% of a volume of the electric motor is enclosed by the support arm. Thus, the electric motor is significantly embedded into the support arm, thereby providing both improved motor protection and heat transport.

According to aspects, the battery compartment comprises a battery lock mechanism, the battery lock mechanism comprising a locking member rotatably supported on a shaft, the locking member comprising a leading edge portion arranged to enter a recess formed in the electrical energy source to lock the electrical energy source in position. The leading edge portion has an arcuate form with a curvature corresponding to that of a circle segment with radius corresponding to the distance from the leading edge portion to the center of the shaft. The recess formed in the energy source comprises a surface arranged to engage the leading edge portion, wherein the surface has an arcuate form configured to match that of the leading edge portion.

This battery lock mechanism allows for inserting a battery into the battery compartment in an effortless manner. The battery lock mechanism then securely holds the battery in position until it is to be removed. The arcuate form of the leading edge portion and the matching surface in the recess allows for a convenient release of the battery from the battery compartment.

According to some aspects, the battery compartment comprises at least one resilient member arranged to urge the electrical energy source into the locking position, wherein the at least one resilient member and the locking member are arranged at opposite sides of the battery compartment.

The at least one resilient member biases the battery into the locked position, thereby providing a more secure fastening of the battery. Also, by arranging the resilient member and the locking mechanisms on opposite sides, a twisting motion by the battery in relation to the battery compartment is obtained, similar to a stuck desk drawer which further secures the battery in the battery compartment.

According to some aspects, the locking member is spring biased towards the locking position, and operable by means of a lever or push-button mechanism. The biasing allows for an at least partly automatic locking function, while the lever or push-button mechanism can be conveniently operated by a user of the tool, which is an advantage.

The present disclosure will now be described in more detail with reference to the appended drawings, where.

<FIG> shows a hand-held work tool <NUM>. The work tool <NUM> in <FIG> comprises a rotatable circular cutting tool <NUM>, but the techniques disclosed herein can also be applied to other cutting tools such as chain-saws, core drills, and the like. An electric motor <NUM> is arranged to drive the cutting tool. This motor is powered from an electrical energy storage device which is arranged to be held in a battery compartment <NUM>.

The electrical motor generates a substantial amount of heat during operation. To prevent the motor from overheating, a fan <NUM> is arranged to be driven by the motor <NUM>. This fan may, e.g., be attached directly to the motor axle, or by some means of transmission arrangement. The fan generates an airflow which transports heat away from the electric motor, thereby cooling the motor.

The work tool <NUM> is arranged to be held by a front handle <NUM> and a rear handle <NUM> and operated by a trigger <NUM> in a known manner. It is desirable to minimize vibration in the handles and trigger, since excessive vibration may be uncomfortable for an operator using the work tool <NUM>. Excessive vibration may also reduce the lifetime of tool components such as cable connections and electronics. To reduce these vibrations, the work tool <NUM> comprises a first part <NUM> and a second part <NUM> arranged vibrationally isolated from each other. The first part <NUM> comprises an interface for holding the cutting tool <NUM> and also comprises the electric motor <NUM> arranged to drive the cutting tool. Thus, the first part comprises the main vibration generating elements of the work tool.

Notably, the second part <NUM> comprises the handles <NUM>, <NUM> and the trigger <NUM> and therefore is the part which interfaces with the operator of the work tool <NUM>. The second part <NUM> also comprises the battery compartment <NUM> for holding the electrical storage device, and the control electronics for controlling various operations of the work tool <NUM>.

Since vibration generated in the first part <NUM> is not transferred, or at least not transferred in a significant amount, to the second part <NUM>, an operator of the device <NUM> will not be subjected to the vibration, which is an advantage since he or she may be able to work for a longer period of time under more comfortable work conditions.

Vibration is normally measured in units of m/s<NUM>, and it is desired to limit tool vibration in front and rear handles below <NUM>/s<NUM>. Tool vibration, guidelines for limiting tool vibration, and measurement of the tool vibration are discussed in "VIBRATIONER - Arbetsmiljöverkets föreskrifter om vibrationer samt allmänna rad om tillämpningen av föreskrifterna", Arbetsmiljöverket, AFS <NUM>:<NUM>.

According to some aspects, the work tool <NUM> comprises a first part <NUM> and a second part <NUM> arranged vibrationally isolated from each other by a vibration isolation system arranged to limit front and rear handle vibration to values below <NUM>/s<NUM>.

A cooling air conduit is arranged to guide a portion of the flow of cooling air <NUM> from the first part <NUM> and into the second part <NUM> for cooling the electrical storage device. This means that the fan <NUM> is used to cool both the electrical motor <NUM>, and the electrical energy source, which is an advantage since only a single fan is needed.

Herein, a conduit is a passage arranged to guide a flow, such as a flow of air. A cooling air conduit may be formed as part of an interior space enclosed by work tool body parts, or as a hose of other type of conduit, or as a combination of different types of conduits.

Any control electronics comprised in the second part <NUM> may also be arranged to be cooled by the portion of the flow of cooling air <NUM> which is guided from the first part <NUM> and into the second part <NUM>. <FIG> schematically shows a cooling flange <NUM> associated with such control electronics, which cooling flange <NUM> is optional, i.e., the portion of the flow of cooling air can be used to cool the control unit directly in which case the control unit constitutes the cooling flange. Thus, optionally, the portion of the flow of cooling air <NUM> from the first part <NUM> and into the second part <NUM> is arranged to pass a cooling flange <NUM> associated with a control unit of the hand-held work tool <NUM>.

It may be a challenge to efficiently guide the portion of air <NUM> from the first part and into the second part, at least partly since the first part and the second part are arranged vibrationally isolated from each other. Some aspects of the disclosed work tool solve this challenge by providing bellows or some other type of flexible air flow conduit between the first part and the second part to guide the portion of air from the fan <NUM> towards the battery compartment <NUM>. These bellows <NUM> will be discussed in more detail below in connection to <FIG>. Bellows are sometimes also referred to as flexible covers, convolutions, accordions, or machine way covers. A hose formed in a flexible material may be used instead of the bellows.

To summarize, <FIG> schematically illustrates a hand-held work tool <NUM> comprising a first part <NUM> and a second part <NUM> arranged vibrationally isolated from each other. According to some aspects, the first part <NUM> is vibrationally isolated from the second part <NUM> by one or more resilient elements.

The hand-held work tool may be a cut-off tool as shown in <FIG>, but it can also be a chain saw or other work tool for cutting hard materials. The first part comprises an interface for holding a cutting tool <NUM> and an electric motor <NUM> arranged to drive the cutting tool. The drive arrangement may, e.g., comprise a belt drive or a combination of belt drive and geared transmission. The electric motor <NUM> is arranged to drive a fan <NUM> configured to generate a flow of cooling air for cooling the electric motor <NUM>. The fan may, e.g., be directly connected to the electric motor shaft, or it can be indirectly connected to the motor shaft via some sort of transmission or drive arrangement, like a belt drive or a geared transmission.

The second part <NUM> comprises a battery compartment <NUM> for holding an electrical storage device arranged to power the electric motor <NUM>, and a cooling air conduit is arranged to guide a portion of the flow of cooling air <NUM> from the first part <NUM> and into the second part <NUM> for cooling the electrical storage device. The electrical energy source may be a battery, or some type of fuel-cell or the like.

<FIG> show different views of an example hand-held work tool <NUM> arranged to hold a cutting tool by a cutting tool interface <NUM>. The resilient elements separating the first part <NUM> from the second part <NUM> are here compression springs <NUM>. However, as mentioned above, some type of resilient material members, such as rubber bushings, may also be used as an alternative to the springs or in combination with the springs. Leaf springs may also be an option for vibrationally isolating the first part <NUM> from the second part <NUM>.

<FIG> shows a holder <NUM> for an extra blade bushing. Cutting blades may have varying dimensions when it comes to the central hole in the blade. Some blade holes are <NUM> across, while some other holes are <NUM>,<NUM> across. There are even some markets where blade central holes of <NUM>,<NUM> are common. To allow use with different types of blades, having different dimensions on the central blade hole, the hand-held work tool <NUM> comprises a holder <NUM> arranged on the work tool body for holding a blade bushing. This extra blade bushing preferably has a different dimension compared to the blade bushing mounted in connection to the cutting tool interface <NUM>.

<FIG> shows an example electrical storage device <NUM>, here a battery, fitted in the battery compartment <NUM>. This battery may be held in position by means of a battery lock mechanism which will be discussed in more detail below in connection to <FIG>, <FIG>.

According to some aspects, the flow of cooling air for cooling the electric motor <NUM> extends transversally <NUM>, <NUM>, <NUM> through the hand-held work tool, with respect to an extension plane of the circular cutting tool <NUM>. Here, with reference to <FIG>, transversally is to be interpreted relative to an extension direction <NUM> of the work tool extending from the rear handle <NUM> towards the cutting tool and in relation to an extension plane of the cutting tool <NUM> (which is more or less vertical in <FIG>). Air from the environment is sucked into the work tool interior via an air intake <NUM> on one side of the tool and at least partly pushed out from the work tool interior via a first air outlet <NUM> on the other side of the tool formed in a direction transversal from the air intake <NUM>.

A portion of the air flow sucked into the work tool via the air inlet <NUM> is guided via an air conduit into the second part <NUM> where it is used to cool the electrical storage device and optionally also cool portions of electrical control circuitry. With reference to, e.g., <FIG>, this portion of the air flow is guided downwards from the fan and then backwards in the tool towards the battery compartment <NUM> before it exits the work tool via a second air outlet <NUM> formed in the second part <NUM> of the tool.

It is appreciated that the air flow can be directed also in the reverse direction if the fan is run in reverse. , the air outlets <NUM>, <NUM> can also be used to suck cool air from the environment into the work tool <NUM>, <NUM>, and the air intake <NUM> can be re-purposed to instead allow hot air to exit the work tool.

With reference to <FIG>, the portion of the air flow <NUM> guided downwards from the fan and then backwards in the tool also exits the work tool via a third air outlet <NUM> formed inside the battery compartment <NUM>. This third outlet is mainly arranged to cool a battery received in the battery compartment <NUM>.

<FIG> illustrates some aspects of the disclosed work tool, wherein the first part <NUM> comprises a thermally conductive support arm <NUM> arranged to support the circular cutting tool <NUM> on a first end of the support arm <NUM>, and to support the electric motor <NUM> by a support surface <NUM> at a second end of the support arm <NUM> opposite to the first end <NUM>. The motor <NUM> is then arranged to drive the cutting tool via some type of drive arrangement, such as a belt drive or a combination of belt drive and geared transmission. The belt is not shown in <FIG>, only the belt pulley. The support surface <NUM> represents a relatively large interfacing area between the motor <NUM> and the support arm <NUM>, which allows for a significant amount of heat transfer from the motor and into the support arm material, at least if the electric motor comprises a corresponding surface for interfacing with the support surface. This heat is then dissipated from one or more cooling flanges <NUM> formed on the support arm <NUM>. Thus, the support arm <NUM> comprises one or more cooling flanges <NUM> arranged to dissipate heat away from the electric motor <NUM> via the support surface <NUM>.

The support arm <NUM> is an arm of the cut-off tool, it may equivalently be referred to as a cut-off arm <NUM>.

This heat transfer arrangement improves the heat dissipation from the motor since the cooling air flow is more efficiently utilized to transport the heat away from the motor.

The more thermally conductive the support arm is, the more efficient is the heat dissipation. According to some aspects, at least some parts of the support arm is formed in a material having a thermal conductivity property above <NUM> Watts per meter and Kelvin (W/mK). For instance, at least some parts of the support arm may be formed in aluminum, which has a thermal conductivity of about <NUM> W/mK. Iron or steel is another option which would provide the desired thermal conductivity. The support arm may also be formed in different materials, i.e., one highly thermally conductive material such as copper, magnesium or aluminum can be used for the cooling flanges and another material, such as cast iron or steel, to provide general structural support.

<FIG> and <FIG> show details of an example support arm <NUM> arranged to support the circular cutting tool <NUM> on a first end of the support arm <NUM>, and to support the electric motor <NUM> by a support surface <NUM> at a second end of the support arm <NUM> opposite to the first end <NUM>. <FIG> shows a view of the support arm <NUM> and the interior space <NUM> discussed above. <FIG> shows a first cross-sectional view along line A-A and <FIG> shows a second cross-sectional view along line B-B. The motor <NUM> comprises a motor axle extending through the motor housing <NUM> in a known manner.

A first end <NUM> of the axle is arranged to hold a pulley for driving the circular cutting tool <NUM>. <FIG> shows a view of the support arm <NUM> with the drive pulleys and the drive belt in place to drive the circular cutting tool <NUM>.

A second end <NUM> of the motor axle is arranged to drive the fan <NUM>. The example fan <NUM> shown in <FIG> is a regular axial fan. Another more advanced example of the fan <NUM> will be discussed below in connection to <FIG>.

Optionally, the support arm <NUM> is arranged to enclose the electric motor at least partially <NUM>, thereby protecting the motor and improving the cooling efficiency of the air flow <NUM> past the motor. Towards this end, the support arm <NUM> comprises a cup-shaped recess, seen in detail in <FIG>, where the support surface <NUM> makes up the bottom portion of the recess and a cylinder shaped wall <NUM> extends out from a perimeter of the support surface <NUM> to enclose the motor housing <NUM> of the electric motor <NUM> when the motor is supported on the support surface <NUM>. The motor <NUM> is arranged to be firmly bolted onto the support surface <NUM> through bolt holes <NUM>, thereby ensuring good thermal conduction between the motor <NUM> and the support arm <NUM> as well as mechanical integrity. A slot is formed between the cylinder shaped wall <NUM> and the motor <NUM>, i.e., the recess wall <NUM> is distanced radially from the motor housing. This slot is arranged to guide a flow of cooling air <NUM> from the fan <NUM> past the motor <NUM>. The flow <NUM> extends transversally from the fan <NUM> through the support arm <NUM> to cool the electric motor <NUM>. The flow of cooling air <NUM> then passes through the openings <NUM> and into the interior space <NUM> and then out via the first air outlet <NUM> shown in <FIG>.

According to some aspects, at least <NUM>% of a volume of the electric motor <NUM>, i.e., the volume of the electric motor including its housing <NUM>, is enclosed by the support arm <NUM>. This means that the cylinder shaped wall <NUM> extends a distance <NUM> from the support surface <NUM> to enclose at least <NUM>% of the volume of the motor housing <NUM>. Thus, the motor is optionally significantly embedded into the support arm, or even entirely embedded as shown in <FIG>, thereby improving both structural integrity of the motor and support arm assembly, as well as improving heat transport away from the electric motor. The cooling of the electric motor <NUM> is also improved by the slot formed between the cylinder shaped wall and the electric motor housing, which cooperates with the thermally conductive support arm and the cooling flanges to cool the motor efficiently.

The support arm <NUM> and the electric motor <NUM> may also be at least partially integrally formed. This means that some parts of the electric motor <NUM> may be shared with the support arm <NUM>. For instance, a part of the support arm <NUM> may constitute part of the electric motor housing, such as a motor gable facing the support arm. The common part shared between the support arm <NUM> and the electric motor <NUM> may, e.g., be machined or molded. Also, optionally, the electric motor axle may bear against a surface of the support arm, to improve mechanical integrity.

It is noted that the feature of an at least partially integrally formed support arm and electric motor can be advantageously combined with the other features disclosed herein but is not dependent on any of the other features disclosed herein. Thus, there is disclosed herein a support arm <NUM> and electric motor <NUM> assembly for a work tool <NUM>, where the support arm and the electric motor are at least partially integrally formed.

With reference to <FIG>, the first part <NUM> optionally comprises a belt guard <NUM> configured to enclose the interior space <NUM>. As discussed above, a portion of the flow of cooling air is arranged to be guided into the interior space <NUM>, thereby increasing an air pressure in the belt guard <NUM> interior space <NUM> above an ambient air pressure level. The interior space <NUM> is delimited on one side by the support arm (discussed below in connection to <FIG>), and on the other side by the belt guard <NUM>, which assumes the function of a lid arranged to engage the support arm to protect the drive belt among other things. The belt guard <NUM> comprises an air outlet <NUM> through which the flow of cooling air exits the interior space. This air outlet <NUM> is configured with an area such that the air pressure in the belt guard <NUM> interior space <NUM> increases above the ambient air pressure level by a desired amount.

The increase in air pressure in the interior space <NUM> means that a flow of air will exit through all openings into the interior space <NUM>, i.e., any cracks and the like, and not just the air outlet <NUM>. This in turn means that water, dust, debris, and slurry will have to overcome this flow of air in order to enter into the interior. Thus, accumulation of unwanted material inside the work tool is reduced.

Water inside the interior space <NUM> may cause the belt drive to slip and is therefore undesirable. The increase in air pressure in the belt guard <NUM> interior space <NUM> means that less water is able to enter the interior space, which is an advantage. As a consequence, requirements on the belt can be reduced, such that, e.g., belts with a smaller number of ribs can be used.

As noted above, the portion of the flow of cooling air <NUM> guided from the first part <NUM> and into the second part <NUM> may pass via a bellows or other flexible air flow conduit <NUM> arranged in-between the first <NUM> and the second <NUM> parts. <FIG> shows an example of such bellows <NUM> in detail.

According to some aspects, the bellows <NUM> is associated with a Shore durometer value, or Shore hardness, between <NUM>-<NUM>, and preferably between <NUM>-<NUM>, measured with durometer type A according to DIN ISO <NUM>-<NUM>.

The bellows <NUM> optionally comprises a poka-yoke feature <NUM>, <NUM>. This poka-yoke feature comprises at least one protrusion <NUM>, <NUM> configured to enter a corresponding recess formed in the first part <NUM> and/or in the second part <NUM>, thereby preventing erroneous assembly of the bellows with the first <NUM> and second <NUM> parts.

The bellows <NUM> also optionally comprises at least one edge portion <NUM>, <NUM> of increased thickness. Each such edge portion is arranged to enter a corresponding groove formed in the first part <NUM> or in the second part <NUM>, thereby fixing the bellows <NUM> in relation to the first or second part similar to a sail leech fitting into a mast. <FIG> schematically illustrate a bellows fitted onto the first and second parts, respectively, by the edge portions.

The bellows illustrated in <FIG> is arranged with a shape that is symmetric about a symmetry plane <NUM> parallel to an extension direction of the edge portions <NUM>, <NUM>. Thus, advantageously, the bellows can be assembled with the first and second parts independently of which side of the bellows that is facing upwards. , the bellows can be rotated <NUM> degrees about the symmetry axis <NUM> and assembled with the first and second parts.

<FIG> schematically illustrate aspects of the battery compartment <NUM>, where the battery compartment comprises a battery lock mechanism <NUM>. The battery lock mechanism comprises a locking member <NUM> rotatably supported on a shaft <NUM>. The locking member comprises a leading edge portion <NUM> arranged to enter a recess <NUM> formed in the electrical energy source <NUM> to lock the electrical energy source in position, wherein the leading edge portion <NUM> has an arcuate form with a curvature corresponding to that of a circle segment with radius <NUM> corresponding to the distance from the leading edge portion <NUM> to the center of the shaft <NUM>, and wherein the recess <NUM> formed in the energy source <NUM> comprises a surface <NUM> arranged to engage the leading edge portion <NUM>, wherein the surface <NUM> has an arcuate form to match that of the leading edge portion <NUM>.

This way, as the electrical energy source <NUM> is received in the battery compartment <NUM>, the locking member is inactive, simply yielding to the electrical energy source as it enters the compartment. This phase of inserting the electrical energy source <NUM> into the compartment <NUM> by moving it in an insertion direction <NUM> is schematically illustrated in <FIG>. The locking member <NUM> then swings into the recess <NUM> where it prevents the battery to be retracted from the battery compartment. The locking position is illustrated in <FIG>. Notably, the arcuate form of the leading edge portion <NUM> allows the locking mechanism to be rotated out of the locking position with less resistance even if there is some friction between the leading edge portion <NUM> and the surface <NUM> arranged to engage the leading edge portion <NUM>.

The locking member may be arranged spring biased towards the locking position, and operable by means of a lever or push-button mechanism, discussed below in connection to <FIG>.

According to some aspects, the battery compartment <NUM> comprises at least one resilient member <NUM> arranged to urge the electrical energy source into the locking position, i.e., urge the electrical energy source in a direction opposite that of the insertion direction <NUM>. The resilient member <NUM>, when compressed by the electrical energy source, pushes onto the electrical energy source to repel it from the battery compartment <NUM>. This pushing force increases the contact pressure between the leading edge portion <NUM> and the surface <NUM> arranged to engage the leading edge portion <NUM>, thereby improving the holding effect on the electrical energy source.

According to an example, a user inserts a battery into the battery compartment in an insertion direction. When the battery is inserted all the way, it contacts the resilient member <NUM> and the locking member <NUM> enters the recess <NUM> formed in the electrical energy source <NUM> to lock the electrical energy source in position. The resilient member, when compressed by the battery, pushes back in a direction opposite to the insertion direction. This pushing force from the resilient member increases a contact force between the leading edge portion <NUM> of the locking member and the surface <NUM> arranged to engage the leading edge portion <NUM>, to hold the battery more securely in position.

The resilient member <NUM> optionally comprises any of a resilient material member, a compression spring, and/or a leaf spring.

The resilient member <NUM> will also eject the electrical energy source <NUM> a short distance from the battery compartment <NUM> when the electrical energy source is released by the locking mechanism <NUM>. Thus, when the bush-button mechanism <NUM> is operated to release a battery, the battery is ejected from the battery compartment <NUM>, making it easier to grasp the battery and pull it out from the battery compartment.

<FIG> schematically shows an example of such resilient members <NUM>. The resilient members urge the electrical energy source in direction <NUM>, but the electrical energy source is prevented from moving in this direction by the locking member <NUM> engaging the recess <NUM>. The arrangement of resilient member <NUM> and locking member <NUM> on opposite sides S1, S2, of the electrical energy source <NUM> generates a twisting motion <NUM> or rotation moment which further increases the holding effect by increasing friction between battery and battery compartment wall, in a manner similar to a stuck cupboard or desk drawer. This further increase in holding effect reduces vibration by the battery since it is now held even more snugly in the battery compartment.

<FIG> shows an example work tool <NUM> which comprises the battery lock mechanism <NUM>. The locking member <NUM> is rotatably supported on a shaft <NUM>, where it is allowed to rotate about an axis <NUM> of rotation. A push-button mechanism <NUM> can be used by the operator to rotate the locking member <NUM> such that it exits the recess, thereby allowing removal of the battery in direction <NUM>.

According to some aspects the locking member <NUM> is spring biased towards the locking position. Thus, as an electrical energy source <NUM> is inserted into the recess <NUM>, the locking member <NUM> snaps into the locking position. The spring bias force can be overcome by the push-button mechanism <NUM> when the electrical energy source is to be removed from the battery compartment.

<FIG> illustrates details of a battery lock mechanism <NUM> for a battery compartment <NUM>. This battery lock mechanism can be used with many different types of tools, i.e., abrasive tools, grinders, chainsaws, drills, cut-of tools, and the like. Thus, the battery lock mechanisms disclosed herein are not limited to use with the cut-off tools discussed above in connection to <FIG>.

The battery lock mechanism <NUM> shown in <FIG> comprises a locking member <NUM> rotatably supported on a shaft <NUM> and optionally spring biased into a locking position as discussed above. The locking member comprises a leading edge portion <NUM> arranged to enter a recess <NUM> formed in the electrical energy source <NUM> to lock the electrical energy source in position, as discussed above in connection to <FIG>. The leading edge portion <NUM> may have an arcuate form with a curvature corresponding to that of a circle segment with radius <NUM> corresponding to the distance from the leading edge portion <NUM> to the center of the shaft <NUM>. The recess <NUM> formed in the energy source <NUM> comprises a surface <NUM> arranged to engage the leading edge portion <NUM>. This surface <NUM> has an arcuate form to match that of the leading edge portion <NUM>. Notably, the battery lock mechanism <NUM> illustrated in <FIG> comprises two locking members <NUM> separated by a distance. This double arrangement of locking members improves robustness of the lock mechanism <NUM>.

Thus, as explained in connection to <FIG>, an electrical energy source such as a battery can be inserted into the battery compartment in an insertion direction <NUM>, i.e., into the compartment <NUM> shown in <FIG>. At some point the locking member is able to enter into the locking position, i.e., it enters the recess <NUM>. In this position the battery is prevented from moving in a direction <NUM> opposite to the insertion direction <NUM>. However, it may rattle some and may not be firmly secured. To improve the battery lock mechanism and to better hold the electrical energy source in position, one or more resilient members <NUM>, such as compression springs or rubber bushings, are arranged in the battery compartment <NUM> and/or on the electrical energy source to push on the electrical energy source as it is inserted all the way into the compartment. The pushing force increases a contact force between the leading edge portion <NUM> and the surface <NUM> configured to engage the leading edge portion. This increased contact force increases friction to better hold the electrical energy source in position.

According to some aspects, the at least one resilient member <NUM> and the battery lock mechanism <NUM> are arranged at opposite sides S1, S2 of the battery compartment <NUM>, i.e., there is a plane <NUM> that divides the battery compartment in two parts, where the resilient member <NUM> is comprised in one part and the battery lock mechanism is comprised in the other part. This means that the resilient member or members push onto the electrical battery source from a direction to cause a twisting motion <NUM> or torque. This twisting motion can be compared to a drawer which gets stuck in a cupboard or desk. The electrical energy source is then prevented from rattling and is more firmly secured in the battery compartment <NUM>.

<FIG> show an example work tool <NUM> comprising a special type of fan <NUM>. This fan comprises a member, preferably but not necessarily discoid shaped, arranged on the axle of the electric motor <NUM> which also constitutes an axis of rotation of the fan. The member extends in a plane perpendicular to the axis of rotation and comprises two different types of fan portions. A first portion acts as an axial fan and pushes cooling air transversally <NUM> across the work tool <NUM> to cool the electric motor <NUM>. A second section of the fan acts as a radial fan, also known as a centrifugal fan, to push cooling air downwards and into the second part of the work tool in cooperation with a fan scroll matched to the radial fan portion. The fan <NUM> is schematically illustrated in <FIG> and an example of the fan is shown in <FIG> where the direction of rotation <NUM> and the axis of rotation <NUM> have been indicated. <FIG> also indicates the direction <NUM> referred to as 'radially outwards' from the axis of rotation <NUM>.

<FIG> shows an example tool where According to some aspects, the portion of the flow of cooling air <NUM> from the first part <NUM> and into the second part <NUM> is arranged to enter the electrical energy source <NUM> via a third outlet <NUM> arranged inside the battery compartment <NUM>. This connection to the electrical energy source improves cooling efficiency by better cooling, e.g., the cells in a battery.

The fan <NUM> comprises an axial fan portion <NUM> arranged peripherally on the fan <NUM>, i.e., circumferentially along the fan disc border as shown in <FIG> and in <FIG>, and a radial fan portion <NUM> arranged centrally on the fan <NUM>, i.e., radially inwards from the axial fan portion as shown in <FIG>. Thus, the axial fan portion is arranged radially outwards <NUM> in the extension plane from the axis of rotation <NUM>. The axial fan portion <NUM> is arranged to generate the flow of cooling air <NUM> for cooling the electric motor <NUM>, and the radial fan portion <NUM> is arranged to generate the portion of the flow of cooling air <NUM> from the first part <NUM> and into the second part <NUM> for cooling the electrical storage device.

Axial flow fans, or axial fans, have blades that force air to move parallel to the shaft about which the blades rotate, i.e., the axis of rotation. This type of fan is used in a wide variety of applications, ranging from small cooling fans for electronics to the giant fans used in wind tunnels. The axial fan is particularly suitable for generating large air flows in straight tube-line conduits, which is the case here when cooling the electric motor <NUM>.

Radial fans, or centrifugal fans, uses the centrifugal power supplied from the rotation of impellers to increase the kinetic energy of air/gases. When the impellers rotate, the gas particles near the impellers are thrown off from the impellers, then move into the fan housing wall. The gas is then guided to the exit by a fan scroll. A radial fan, compared to the axial fan, is better at pushing cooling air at a pressure passed air conduits with bends and narrow passages, which is the case for the air conduit passing into the second part and towards the battery compartment <NUM>.

According to some aspects, the axial fan and the radial fan are formed as separate parts mounted on the same motor axle.

The radius of the radial fan may correspond to the radius of the electrical motor gable.

The relationship between the radius of the radial fan and the radius of the fan may be on the order of <NUM>-<NUM> percent.

Thus, advantageously, the fan illustrated in <FIG> provide both efficient motor cooling as well as efficient cooling of tool members in the second part, e.g., the control unit and the electrical energy source. This is achieved by providing two different types of fans on a single fan member.

<FIG> shows a more detailed view of the part of the support arm which comprises the one or more cooling flanges <NUM> arranged to dissipate heat away from the electric motor <NUM> via the support surface <NUM>. The openings <NUM> for letting air enter the interior space <NUM> discussed above can also be seen. The axial fan portion <NUM> pushes air past the motor and through these holes, thereby cooling the electric motor <NUM>.

The fan <NUM> may optionally be assembled in a fan housing <NUM> exemplified in <FIG>. The fan housing comprises at least one opening <NUM> arranged peripherally and radially outwards from the axis of rotation <NUM> to receive the flow of cooling air <NUM> from the axial fan portion <NUM> for cooling the electric motor <NUM>. The fan housing also comprises a fan scroll <NUM> arranged centrally in the housing to interface with the radial fan portion <NUM> for guiding the portion of the flow of cooling air <NUM> from the first part <NUM> and into the second part <NUM> for cooling the electrical storage device.

<FIG> also shows the grooves <NUM> and the recesses <NUM> for receiving the bellows <NUM> with the edge portions <NUM> and the poka-yoke feature <NUM> illustrated in <FIG>.

The fan discussed in connection to <FIG>, B, <NUM>, <NUM>, and <NUM> is not only applicable to the types of work tools disclosed herein. On the contrary, this fan can be used with advantage in any type of work tool where a first flow of cooling air and a second flow is desired. Thus, there is disclosed herein a fan <NUM> for a hand-held work tool <NUM>, <NUM>, <NUM>, <NUM>. The fan <NUM> extends in a plane perpendicular to an axis of rotation of the fan <NUM>. The fan comprises an axial fan portion <NUM> arranged radially outwards <NUM> from a radial fan portion <NUM> arranged centrally on the fan <NUM> with respect to the axis of rotation <NUM>, wherein the axial fan portion <NUM> is arranged to generate a first flow of cooling air for cooling a first hand-held work tool member, and wherein the radial fan portion <NUM> is arranged to generate a second flow of cooling air <NUM> for cooling a second hand-held work tool member.

Optionally, the axial fan portion <NUM> has an annular shape centered on the axis of rotation <NUM>, and wherein the radial fan portion <NUM> has a discoid shape centered on the axis of rotation <NUM>.

There is also disclosed herein a hand-held work tool <NUM> comprising the fan discussed in connection to <FIG>, and a fan housing <NUM>. The fan <NUM> is assembled in the fan housing <NUM>, which fan housing comprises at least one opening <NUM> arranged peripherally in the fan housing and radially outwards from the axis of rotation <NUM> of the fan <NUM> to receive the first flow of cooling air from the axial fan portion <NUM> for cooling the first hand-held work tool member, the fan housing also comprises a fan scroll <NUM> arranged centrally in the fan housing to interface with the radial fan portion for guiding the second flow of cooling air <NUM> for cooling a second hand-held work tool member.

<FIG> illustrates details of an optional connector arrangement <NUM> for a water hose which is preferably mounted in vicinity of the rear handle <NUM> where it is easily accessible by an operator to attach and to detach a water hose. The connector arrangement <NUM> comprises a water hose connector part <NUM>, here shown as a nipple, i.e. a connector male part, for a water hose quick connector system facing rearwards away from the circular cutting tool <NUM>. The connector nipple <NUM> is mounted fixedly onto the machine housing by a bracket <NUM> such that the water hose connector part <NUM> is fixedly held in relation to the work tool. Alternatively, a female water hose connector part can be fixedly mounted onto the work tool by a similar bracket to obtain the same technical effect and advantages. A water hose <NUM> extends away from the connector part <NUM> towards the cutting tool <NUM>. The water hose <NUM> is arranged at least partly embedded into the tool housing, in order to protect the water hose from damage during use of the tool <NUM>.

Known water hose connector arrangements often comprise a segment of hose in-between a bracket on the work tool and the connector part (male or female connector part), which means that it is difficult to connect and to disconnect the water hose with a single hand. The connector arrangement <NUM>, however, allows for attachment and detachment of a water hose for supplying water to the cutting tool <NUM> during operation by one hand, since the connector nipple <NUM> is mounted fixedly onto the machine housing by the bracket <NUM>. Thus, the connector part is firmly supported by the machine housing where it is easily accessible and does not move around. An operator may, for instance, hold the tool by the front handle <NUM> with one hand and connect the water hose with the other hand. The connector part <NUM> may be adapted for interfacing with any quick connector system on the market, such as the Gardena ® water hose system.

The water hose connector arrangement <NUM> comprising the connector part <NUM> and the bracket <NUM> can be implemented on any power tool requiring a supply of water, it is not limited to the particular tools discussed herein.

<FIG> show views of the connector arrangement <NUM> in more detail. <FIG> is a view corresponding to that in <FIG>, while <FIG> shows the connector arrangement <NUM> from an opposite point of view. The connector part <NUM> and the bracket <NUM> are preferably integrally formed, i.e., machined or molded from one piece of material, such as a piece of plastic or metal. An internal nipple <NUM> for attaching the water hose <NUM> may be arranged opposite to the connector part <NUM> for convenient assembly of the connector arrangement on the hand-held work tool.

<FIG> illustrate details of an example battery compartment <NUM>. An electrical energy source such as a battery can be inserted into the battery compartment in an insertion direction <NUM>, i.e., into the compartment <NUM> as also shown in <FIG>. <FIG> is a view opposite to the insertion direction <NUM>, while <FIG> is a view looking into the compartment <NUM> in the insertion direction <NUM>. The locking members <NUM>, discussed above in connection to, e.g., <FIG> can be seen in <FIG>. The battery, which will be discussed in more detail below in connection to <FIG> optionally comprises a rearward face formed as a handle to simplify both insertion and removal of the battery in the battery compartment <NUM>.

Batteries for powering heavy duty cut-off tools such as the work tools discussed herein are normally quite heavy. Thus, the batteries must be held in the battery compartment <NUM> in a robust and reliable manner. Towards this end, the battery compartment <NUM> comprises a battery holding mechanism specifically adapted to support a heavy battery, i.e., weighting on the order of <NUM>, such as between <NUM>-<NUM>.

The battery compartment <NUM> extends transversally through the housing of the tool <NUM>, <NUM> as discussed above, where it defines a volume for receiving a battery. The volume is delimited by a rear wall Rw and a front wall Fw, where the rear wall Rw is located towards the rear handle <NUM> on the tool <NUM> and the front wall Fw is located towards the front of the tool <NUM>, i.e., towards the cutting tool <NUM>. A bottom surface Bs and a top surface Fs also delimits the volume. The example volume in <FIG> is of a rectangular shape with rounded corners.

The battery holding mechanism comprises a supporting heel <NUM> arranged on a middle section of a side wall of the battery compartment, more specifically on the rear wall Rw closest to the rear handle <NUM>. The heel is <NUM> elongated with an elongation direction extending transversally through the battery compartment aligned with an insertion direction of the battery in the battery compartment <NUM>. When the machine is resting on the ground support member <NUM>, the supporting heel <NUM> is parallel to ground. Also, when the tool <NUM> is held in a normal operating position, the supporting heel is parallel to ground, and therefore supports the battery against gravity. It is appreciated that the supporting heel <NUM> can also be arranged on the front wall, i.e., on any of the front wall and/or the rear wall of the battery compartment. The battery, which is exemplified in <FIG> and will be discussed below, comprises a corresponding groove matched to the supporting heel.

According to some aspects the supporting heel <NUM> is metal shod for increased mechanical integrity, i.e., the supporting heel <NUM> is optionally constructed with an outer layer metal layer for increased mechanical robustness.

According to some other aspects, the battery compartment also comprises an upper dove-tail groove <NUM> and a lower dove-tail groove <NUM> for supporting the battery in the battery compartment <NUM>. The dove-tail grooves are arranged to mate with corresponding ridge structures on the battery, such that the battery can be inserted into the battery compartment <NUM> in mating position with the dove-tail grooves in the insertion direction <NUM>. Thus, the supporting heel <NUM> and the dove-tail grooves <NUM>, <NUM> collaborate to support the battery in the battery compartment in a safe and roust manner. The dove-tail grooves <NUM>, <NUM> have the function to guide the battery as it is inserted into the battery compartment <NUM> and prevents snagging as the battery is removed from the battery compartment <NUM>.

According to some aspects, the dove-tail grooves <NUM>, <NUM> are metal shod for increased mechanical strength, i.e., the grooves are reinforced with a lining layer of metal for increased mechanical robustness.

<FIG> also shows two resilient members <NUM> as discussed above in connection to <FIG>, arranged to urge the battery into the locking position, i.e., urge the electrical energy source in a direction opposite that of the insertion direction <NUM>.

Contact strips <NUM> extending in the insertion direction <NUM> are arranged in the battery compartment <NUM> to mate with corresponding electrical connectors configured in slots on the battery.

There is also disclosed herein a battery <NUM> as shown in <FIG> for insertion into the battery compartment <NUM>. The battery <NUM> has a weight between <NUM>-<NUM> and comprises a groove <NUM> arranged on one side of the battery to mate with a corresponding supporting heel <NUM> arranged on a wall of a battery compartment <NUM>. The groove optionally has an initial bevel to simplify mating with the supporting heel <NUM>. The battery <NUM> further comprises an upper ridge structure <NUM> and a lower ridge structure <NUM> on an opposite side of the battery compared to the groove <NUM>, as shown in <FIG>, for mating with corresponding dove-tail grooves <NUM>, <NUM> of the battery compartment <NUM>. Thus, the battery <NUM> is configured for insertion into the battery compartment <NUM> discussed in connection to <FIG>.

The battery <NUM> comprises at least one recess <NUM> configured to receive a respective locking member <NUM> of a battery lock mechanism <NUM> as discussed above. The locking member comprises a leading edge portion <NUM> with an arcuate form and the recess <NUM> comprises a surface <NUM> arranged to engage the leading edge portion <NUM>. The surface <NUM> has an arcuate form to match that of the leading edge portion <NUM>. Two recesses are advantageously arranged on either side of the elongated supporting heel <NUM> as shown in <FIG>.

The battery <NUM> exemplified in <FIG> also comprises one or more electrical connectors <NUM> arranged protected in slots extending in the insertion direction to mate with corresponding contact strips <NUM> arranged in the battery compartment <NUM>.

Optionally, the battery <NUM> comprises a forward face F1 facing in the insertion direction <NUM> when the battery <NUM> is inserted in the battery compartment <NUM>, and a rearward face F2 opposite to the forward face, wherein the rearward face is formed as a handle <NUM> to allow gripping by one hand.

The battery also comprises electrical connectors <NUM> configured in slots extending in the insertion direction to mate with corresponding contact strips <NUM> arranged in the battery compartment <NUM>. The electrical connectors are thereby protected from mechanical impact.

To promote cooling of the battery, there is an air inlet arranged on a bottom side of the battery which is in fluid communication with an air outlet <NUM> arranged on the upper side of the battery, as seen in <FIG>. Thus, the air stream <NUM> from the fan <NUM> can be guided through the battery <NUM> to better cool the battery cells.

Claim 1:
A hand-held work tool (<NUM>, <NUM>, <NUM>, <NUM>) comprising a first part (<NUM>) and a second part (<NUM>) arranged vibrationally isolated from each other,
the first part (<NUM>) comprising an interface for holding a cutting tool (<NUM>) and an electric motor (<NUM>) arranged to drive the cutting tool, wherein the electric motor (<NUM>) is arranged to drive a fan (<NUM>) configured to generate a flow of cooling air for cooling the electric motor (<NUM>),
the second part (<NUM>) comprising a battery compartment (<NUM>) for holding an electrical storage device arranged to power the electric motor (<NUM>),
wherein the hand-held work tool comprises a cooling air conduit (<NUM>) arranged between the first part and the second part to guide a portion of the flow of cooling air (<NUM>) there in-between for cooling the electrical storage device.