TITLE

A HAND-HELD ELECTRICALLY POWERED WORK TOOL

TECHNICAL FIELD The present disclosure relates to electrically powered hand-held work equipment such as cut-off tools and saws for cutting concrete and stone.

BACKGROUND

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.

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. SUMMARY

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 comfort- level. 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 cut-off arm arranged to support the circular cutting tool on a first end of the cut-off arm, and to support the electric motor by a support surface at a second end of the cut-off arm opposite to the first end, wherein the cut-off 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 cut-off arm, which is an advantage. The support surface improves a thermal coupling between the electric motor and the cut-off arm, thereby improving heat dissipation from the electric motor, which is an advantage.

According to some further aspects, the cut-off arm is arranged to at least partially enclose the electric motor. The cut-off arm thereby protects the electric motor and also has the function of transporting heat away from the electric motor. According to aspects, the cut-off arm and the electric motor are at least partially integrally formed. This means that the cut-off arm and the electric motor may share some parts. For instance, a part of the electric motor housing may be formed by the cut-off arm material. This part may, e.g., be a motor gable.

According to aspects, at least 30% of a volume of the electric motor is enclosed by the cut-off arm. Thus, the electric motor is significantly embedded into the cut-off 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.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 1 shows an example work tool; Figures 2A-C show views of another example work tool;

Figures 3A-B show views of a work tool cut-off arm;

Figures 4-6 illustrate bellows for guiding an air flow;

Figures 7A-C schematically illustrate a locking mechanism;

Figure 8 shows an example work tool with a battery locking mechanism; Figure 9 schematically illustrates details of a battery lock mechanism; Figures 10A-C show views of an example work tool;

Figure 11 schematically illustrates a fan;

Figure 12 shows an example fan for a work tool; and Figure 13 shows an example fan housing.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

It is to be understood that the present invention is not limited to the embodiments described herein and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. Figure 1 shows a hand-held work tool 100. The work tool 100 in Figure 1 comprises a rotatable circular cutting tool 130, 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 140 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 150.

The electrical motor generates a substantial amount of heat during operation. To prevent the motor from overheating, a fan 145 is arranged to be driven by the motor 140. 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 100 is arranged to be held by a front handle 190 and a rear handle 195 and operated by a trigger 196 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 100. Excessive vibration may also reduce the lifetime of tool components such as cable connections and electronics. To reduce these vibrations, the work tool 100 comprises a first part 110 and a second part 120 arranged vibrationally isolated from each other. The first part 110 comprises an interface for holding the cutting tool 130 and also comprises the electric motor 140 arranged to drive the cutting tool. Thus, the first part comprises the main vibration generating elements of the work tool.

Notably, the second part 120 comprises the handles 190, 195 and the trigger 196 and therefore is the part which interfaces with the operator of the work tool 100. The second part 120 also comprises the battery compartment 150 for holding the electrical storage device, and the control electronics for controlling various operations of the work tool 100.

Since vibration generated in the first part 110 is not transferred, or at least not transferred in a significant amount, to the second part 120, an operator of the device 100 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 ² , and it is desired to limit tool vibration in front and rear handles below 2.5 m/s ² . Tool vibration, guidelines for limiting tool vibration, and measurement of the tool vibration are discussed in “VIBRATIONER - Arbetsmiljoverkets foreskrifter om vibrationer samt allmanna rad om tillampningen av foreskrifterna”, Arbetsmiljoverket, AFS 2005:15.

According to some aspects, the work tool 100 comprises a first part 110 and a second part 120 arranged vibrationally isolated from each other by a vibration isolation system arranged to limit front and rear handle vibration to values below 2.5 m/s ² .

A cooling air conduit is arranged to guide a portion of the flow of cooling air 160 from the first part 110 and into the second part 120 for cooling the electrical storage device. This means that the fan 145 is used to cool both the electrical motor 140, 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 120 may also be arranged to be cooled by the portion of the flow of cooling air 160 which is guided from the first part 110 and into the second part 120. Figure 1 schematically shows a cooling flange 180 associated with such control electronics, which cooling flange 180 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 160 from the first part 110 and into the second part 120 is arranged to pass a cooling flange 180 associated with a control unit of the hand-held work tool 100.

It may be a challenge to efficiently guide the portion of air 160 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 145 towards the battery compartment 150. These bellows 170 will be discussed in more detail below in connection to Figures 4-6. 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, Figure 1 schematically illustrates a hand-held work tool 100 comprising a first part 110 and a second part 120 arranged vibrationally isolated from each other. According to some aspects, the first part 110 is vibrationally isolated from the second part 120 by one or more resilient elements.

The hand-held work tool may be a cut-off tool as shown in Figure 1 , 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 130 and an electric motor 140 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 140 is arranged to drive a fan 145 configured to generate a flow of cooling air for cooling the electric motor 140. 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 120 comprises a battery compartment 150 for holding an electrical storage device arranged to power the electric motor 140, and a cooling air conduit is arranged to guide a portion of the flow of cooling air 160 from the first part 110 and into the second part 120 for cooling the electrical storage device. The electrical energy source may be a battery, or some type of fuel-cell or the like.

Figures 2A-C show different views of an example hand-held work tool 200 arranged to hold a cutting tool by a cutting tool interface 260. The resilient elements separating the first part 110 from the second part 120 are here compression springs 210. Flowever, 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 110 from the second part 120.

Figure 2B shows a holder 270 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 20mm across, while some other holes are 25,5mm across. There are even some markets where blade central holes of 30,5mm are common. To allow use with different types of blades, having different dimensions on the central blade hole, the hand-held work tool 200 comprises a holder 270 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 260.

Figure 2A shows an example electrical storage device 220, here a battery, fitted in the battery compartment 150. 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 Figures 7A-C, 8, and 9.

According to some aspects, the flow of cooling air for cooling the electric motor 140 extends transversally 230, 245, 201 through the hand-held work tool, with respect to an extension plane of the circular cutting tool 130. Flere, with reference to Figure 2C, transversally is to be interpreted relative to an extension direction 202 of the work tool extending from the rear handle 195 towards the cutting tool and in relation to an extension plane of the cutting tool 130 (which is more or less vertical in Figure 2C). Air from the environment is sucked into the work tool interior via an air intake 230 on one side of the tool and at least partly pushed out from the work tool interior via a first air outlet 245 on the other side of the tool formed in a direction transversal from the air intake 230.

A portion of the air flow sucked into the work tool via the air inlet 230 is guided via an air conduit into the second part 120 where it is used to cool the electrical storage device and optionally also cool portions of electrical control circuitry. With reference to, e.g., Figure 2B, this portion of the air flow is guided downwards from the fan and then backwards in the tool towards the battery compartment 150 before it exits the work tool via a second air outlet 250 formed in the second part 120 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. I.e. , the air outlets 245, 250 can also be used to suck cool air from the environment into the work tool 100, 200, and the air intake 230 can be re-purposed to instead allow hot air to exit the work tool.

With reference to Figure 10A, the portion of the airflow 160 guided downwards from the fan and then backwards in the tool also exits the work tool via a third air outlet 251 formed inside the battery compartment 151. This third outlet is mainly arranged to cool a battery received in the battery compartment 150.

Figures 3A and 3B illustrates some aspects of the disclosed work tool, wherein the first part 110 comprises a thermally conductive cut-off arm 240 arranged to support the circular cutting tool 130 on a first end of the cut-off arm 241 , and to support the electric motor 140 by a support surface 330 at a second end of the cut-off arm 242 opposite to the first end 241. The motor 140 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 Figure 3A, only the belt pulley. The support surface 330 represents a relatively large interfacing area between the motor 140 and the cut-off arm 240, which allows for a significant amount of heat transfer from the motor and into the cut-off 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 320 formed on the cut-off arm 240. Thus, the cut-off arm 240 comprises one or more cooling flanges 320 arranged to dissipate heat away from the electric motor 140 via the support surface 330.

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 cut-off arm is, the more efficient is the heat dissipation. According to some aspects, at least some parts of the cut-off arm is formed in a material having a thermal conductivity property above 100 Watts per meter and Kelvin (W/mK). For instance, at least some parts of the cut-off arm may be formed in aluminum, which has a thermal conductivity of about 237 W/mK. Iron or steel is another option which would provide the desired thermal conductivity. The cut-off 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.

Optionally, the cut-off arm 240 is arranged to at least partially enclose the electric motor 140, thereby protecting the motor and improving the air flow past the motor. According to some aspects, at least 30% of a volume of the electric motor 140 is enclosed by the cut-off arm 240. Thus, the motor is optionally significantly embedded into the cut-off arm, thereby improving both structural integrity of the motor and cut-off arm assembly, as well as improving heat transport away from the electric motor.

The cut-off arm 240 and the electric motor 140 may also be at least partially integrally formed. This means that some parts of the electric motor may be shared with the cut-off arm. For instance, a part of the cut-off arm 240 may constitute part of the electric motor housing, such as a motor gable facing the cut-off arm. The common part shared between the cut-off arm 240 and the electric motor 140 may, e.g., be machined or molded. Also, optionally, the electric motor axle may bear against a surface of the cut-off arm, to improve mechanical integrity.

It is noted that the feature of an at least partially integrally formed cut-off 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 cut-off arm 240 and electric motor 140 assembly for a work tool 100, where the cut-off arm and the electric motor are at least partially integrally formed.

With reference to Figure 2B, the first part 110 optionally comprises a belt guard 115 configured to enclose the interior space 340. As discussed above, a portion of the flow of cooling air is arranged to be guided 310 into the interior space 340, thereby increasing an air pressure in the belt guard 115 interior space 340 above an ambient air pressure level. The interior space 340 is delimited on one side by the cut-off arm (discussed below in connection to Figures 3A and 3B), and on the other side by the belt guard 115, which assumes the function of a lid arranged to engage the cut-off arm to protect the drive belt among other things. The belt guard 115 comprises an air outlet 245 through which the flow of cooling air exits the interior space. This air outlet 245 is configured with an area such that the air pressure in the belt guard 115 interior space 340 increases above the ambient air pressure level by a desired amount.

The increase in air pressure in the interior space 340 means that a flow of air will exit through all openings into the interior space 340, i.e. , any cracks and the like, and not just the air outlet 245. 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 340 may cause the belt drive to slip and is therefore undesirable. The increase in air pressure in the belt guard 115 interior space 340 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 160 guided from the first part 110 and into the second part 120 may pass via a bellows or other flexible air flow conduit 170 arranged in-between the first 110 and the second 120 parts. Figure 4 shows an example of such bellows 10 in detail.

According to some aspects, the bellows 170 is associated with a Shore durometer value, or Shore hardness, between 10-70, and preferably between 50-60, measured with durometer type A according to DIN ISO 7619-1 .

The bellows 170 optionally comprises a poka-yoke feature 410, 420. This poka-yoke feature comprises at least one protrusion 410, 420 configured to enter a corresponding recess formed in the first part 110 and/or in the second part 120, thereby preventing erroneous assembly of the bellows with the first 110 and second 120 parts. The bellows 170 also optionally comprises at least one edge portion 430, 440 of increased thickness. Each such edge portion is arranged to enter a corresponding groove formed in the first part 110 or in the second part 120, thereby fixing the bellows 170 in relation to the first or second part similar to a sail leech fitting into a mast. Figures 5 and 6 schematically illustrate a bellows fitted onto the first and second parts, respectively, by the edge portions.

The bellows illustrated in Figure 4 is arranged with a shape that is symmetric about a symmetry plane 450 parallel to an extension direction of the edge portions 430, 440. Thus, advantageously, the bellows can be assembled with the first and second parts independently of which side of the bellows that is facing upwards. I.e. , the bellows can be rotated 180 degrees about the symmetry axis 460 and assembled with the first and second parts.

Figures 7A-C schematically illustrate aspects of the battery compartment 150, where the battery compartment comprises a battery lock mechanism 700. The battery lock mechanism comprises a locking member 710 rotatably supported on a shaft 720. The locking member comprises a leading edge portion 750 arranged to enter a recess 760 formed in the electrical energy source 220 to lock the electrical energy source in position, wherein the leading edge portion 750 has an arcuate form with a curvature corresponding to that of a circle segment with radius 740 corresponding to the distance from the leading edge portion 750 to the center of the shaft 720, and wherein the recess 760 formed in the energy source 220 comprises a surface 770 arranged to engage the leading edge portion 750, wherein the surface 770 has an arcuate form to match that of the leading edge portion 750.

This way, as the electrical energy source 220 is received in the battery compartment 150, 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 220 into the compartment 150 by moving it in an insertion direction 701 is schematically illustrated in Figures 7A and 7B. The locking member 710 then swings into the recess 760 where it prevents the battery to be retracted from the battery compartment. The locking position is illustrated in Figure 7C. Notably, the arcuate form of the leading edge portion 750 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 750 and the surface 770 arranged to engage the leading edge portion 750.

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 Figures 8 and 9.

According to some aspects, the battery compartment 150 comprises at least one resilient member 780 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 701. The resilient member 780, when compressed by the electrical energy source, pushes onto the electrical energy source to repel it from the battery compartment 150. This pushing force increases the contact pressure between the leading edge portion 750 and the surface 770 arranged to engage the leading edge portion 750, 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 780 and the locking member 710 enters the recess 760 formed in the electrical energy source 220 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 750 of the locking member and the surface 770 arranged to engage the leading edge portion 750, to more securely hold the battery in position.

The resilient member 780 optionally comprises any of a resilient material member, a compression spring, and/or a leaf spring.

The resilient member 708 will also eject the electrical energy source 220 a short distance from the battery compartment 150 when the electrical energy source is released by the locking mechanism 700. Thus, when the bush-button mechanism 810 is operated to release a battery, the battery is ejected from the battery compartment 150, making it easier to grasp the battery and pull it out from the battery compartment.

Figure 7C schematically shows an example of such resilient members 780. The resilient members urge the electrical energy source in direction 702, but the electrical energy source is prevented from moving in this direction by the locking member 710 engaging the recess 760. The arrangement of resilient member 780 and locking member 710 on opposite sides S1, S2, of the electrical energy source 220 generates a twisting motion 795 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.

Figure 8 shows an example work tool 800 which comprises the battery lock mechanism 700. The locking member 710 is rotatably supported on a shaft 720, where it is allowed to rotate about an axis 820 of rotation. A push-button mechanism 810 can be used by the operator to rotate the locking member 710 such that it exits the recess, thereby allowing removal of the battery in direction 702. According to some aspects the locking member 710 is spring biased towards the locking position. Thus, as an electrical energy source 220 is inserted into the recess 150, the locking member 710 snaps into the locking position. The spring bias force can be overcome by the push-button mechanism 810 when the electrical energy source is to be removed from the battery compartment. Figure 9 illustrates details of a battery lock mechanism 700 for a battery compartment 150. 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 Figures The battery lock mechanism 700 shown in Figure 9 comprises a locking member 710 rotatably supported on a shaft 720 and optionally spring biased into a locking position as discussed above. The locking member comprises a leading edge portion 750 arranged to enter a recess 760 formed in the electrical energy source 220 to lock the electrical energy source in position, as discussed above in connection to Figures 7A-C. The leading edge portion 750 may have an arcuate form with a curvature corresponding to that of a circle segment with radius 740 corresponding to the distance from the leading edge portion 750 to the center of the shaft 720. The recess 760 formed in the energy source 220 comprises a surface 770 arranged to engage the leading edge portion 750. This surface 770 has an arcuate form to match that of the leading edge portion 750. Notably, the battery lock mechanism 700 illustrated in Figure 9 comprises two locking members 710 separated by a distance. This double arrangement of locking members improves robustness of the lock mechanism 700.

Thus, as explained in connection to Figures 7A-C, an electrical energy source such as a battery can be inserted into the battery compartment in an insertion direction 701 , i.e. , into the compartment 150 shown in Figure 9. At some point the locking member is able to enter into the locking position, i.e., it enters the recess 760. In this position the battery is prevented from moving in a direction 702 opposite to the insertion direction 701. Flowever, 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 780, such as compression springs or rubber bushings, are arranged in the battery compartment 150 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 750 and the surface 770 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 780 and the battery lock mechanism 700 are arranged at opposite sides S1 , S2 of the battery compartment 150, i.e. , there is a plane 910 that divides the battery compartment in two parts, where the resilient member 780 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 795 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 150.

Figures 10A and 10 B show an example work tool 1000 comprising a special type of fan 145. This fan comprises a member, preferably but not necessarily discoid shaped, arranged on the axle of the electric motor 140 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 airtransversally 201 across the work tool 1000 to cool the electric motor 140. 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 145 is schematically illustrated in Figure 11 and an example of the fan is shown in Figure 12 where the direction of rotation 1130 and the axis of rotation 1140 have been indicated. Figure 11 also indicates the direction 1145 referred to as ‘radially outwards’ from the axis of rotation 1140.

Figure 10A shows an example tool where According to some aspects, the portion of the flow of cooling air 160 from the first part 110 and into the second part 120 is arranged to enter the electrical energy source 220 via a third outlet 251 arranged inside the battery compartment 150. This connection to the electrical energy source improves cooling efficiency by better cooling, e.g., the cells in a battery.

The fan 145 comprises an axial fan portion 1110 arranged peripherally on the fan 145, i.e., circumferentially along the fan disc border as shown in Figure 11 and in Figure 12, and a radial fan portion 1120 arranged centrally on the fan 145, i.e. , radially inwards from the axial fan portion as shown in Figures 11 and 12. Thus, the axial fan portion is arranged radially outwards 1145 in the extension plane from the axis of rotation 1140. The axial fan portion 1110 is arranged to generate the flow of cooling air 1330 for cooling the electric motor 140, and the radial fan portion 1120 is arranged to generate the portion of the flow of cooling air 160 from the first part 110 and into the second part 120 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 140.

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 150.

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 50-70 percent.

Thus, advantageously, the fan illustrated in Figures 10-13 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. Figure 10C shows a more detailed view of the part of the cut-off arm which comprises the one or more cooling flanges 320 arranged to dissipate heat away from the electric motor 140 via the support surface 330. The openings 310 for letting air enter the interior space 340 discussed above can also be seen. The axial fan portion 1110 pushes air past the motor and through these holes, thereby cooling the electric motor 140.

The fan 145 may optionally be assembled in a fan housing 1010 exemplified in Figure 13. The fan housing comprises at least one opening 1310 arranged peripherally and radially outwards from the axis of rotation 1140 to receive the flow of cooling air 1330 from the axial fan portion 1110 for cooling the electric motor 140. The fan housing also comprises a fan scroll 1320 arranged centrally in the housing to interface with the radial fan portion 1120 for guiding the portion of the flow of cooling air 160 from the first part 110 and into the second part 120 for cooling the electrical storage device. Figure 13 also shows the grooves 1340 and the recesses 1350 for receiving the bellows 170 with the edge portions 430 and the poka-yoke feature 410 illustrated in Figure 4.

The fan discussed in connection to Figures 10A, B, 11, 12, and 13 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 145 for a hand-held work tool 100, 200, 800, 1000. The fan 145 extends in a plane perpendicular to an axis of rotation of the fan 1140. The fan comprises an axial fan portion 1110 arranged radially outwards 145 from a radial fan portion 1120 arranged centrally on the fan 145 with respect to the axis of rotation 1140, wherein the axial fan portion 1110 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 1120 is arranged to generate a second flow of cooling air 160 for cooling a second hand-held work tool member. Optionally, the axial fan portion 1110 has an annular shape centered on the axis of rotation 1140, and wherein the radial fan portion 1120 has a discoid shape centered on the axis of rotation 1140.

There is also disclosed herein a hand-held work tool 1000 comprising the fan discussed in connection to Figures 10-13, and a fan housing 1010. The fan 145 is assembled in the fan housing 1010, which fan housing comprises at least one opening 1310 arranged peripherally in the fan housing and radially outwards from the axis of rotation 1140 of the fan 145 to receive the first flow of cooling air from the axial fan portion 1110 for cooling the first hand-held work tool member, the fan housing also comprises a fan scroll 1320 arranged centrally in the fan housing to interface with the radial fan portion for guiding the second flow of cooling air 160 for cooling a second hand-held work tool member.