Handheld electric disc cutter having a specific mass ratio

Abstract

A handheld power cutting tool (100, 200, 800, 1000, 1900, 2500) comprising a first portion (110) and a second portion (120) arranged in vibrational isolation from one another, the first portion (110) comprising an interface (2510) for holding a cutting accessory (130) and an electric motor (140) configured to drive the cutting accessory, the first portion being associated with a first mass (M1), the second portion (120) comprising a battery compartment (150) for holding an electrical storage device (220) configured to power the electric motor (140), and front and rear handles (190 and 195) for manipulating the cutting tool, the second portion being associated with a second mass (M2), the ratio of the second mass (M2) to the sum of the first and second masses (M1+M2) being at least 0.3 and preferably greater than 0.35.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to powered handheld work equipment such as cutting tools and saws for cutting concrete and stone. [Background technology]

[0002] Hand-held work tools for cutting and / or grinding hard materials such as concrete and stone have powerful motors to provide the power required to process the hard materials. These motors generate significant heat and therefore need to be cooled to prevent overheating. Electric work tools generate heat not only from the electric motor but also from the battery and control electronics. A method for efficiently cooling such work tools is needed.

[0003] Working tools usually generate vibrations that can be harmful or at least uncomfortable for the tool operator. It is desirable to protect the operator from prolonged exposure to strong vibrations.

[0004] 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 can adversely affect the performance of the tool. For example, slurry can accumulate inside the work tool and ultimately cause the tool to fail. It is desirable to prevent the accumulation of dust and slurry inside the work tool.

[0005] Ease of operation is particularly important for tools used on construction sites. In the case of electric tools, it is desirable to be able to easily insert the battery into the tool, to have the battery held securely in the tool, to have the battery easily released from the tool, and to be able to perform battery replacement in the field in an efficient and convenient manner.

[0006] In summary, there are challenges associated with hand held power tools. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE DISCLOSURE It is an object of the present disclosure to provide an improved hand held power tool that addresses the above problems. [Means for solving the problem]

[0008] This object is achieved, at least in part, by a handheld electric cutting tool comprising a first part and a second part arranged in vibrational isolation from one another, the first part including an interface for holding a cutting accessory and an electric motor configured to drive the cutting accessory, the first part being associated with a first mass M1, the second part including a battery compartment for holding an electrical storage device configured to power the electric motor, and front and rear handles for manipulating the cutting tool, the second part being associated with a second mass M2.

[0009] The ratio of the second mass M2 to the sum of the first and second masses M1+M2, ie, M2 / (M1+M2), is at least 0.3, preferably greater than 0.35.

[0010] The ratio of the sum of the second and third masses M2+M3 to the sum of the first and fourth masses M1+M4 is at least 0.6, preferably greater than 0.8, and even more preferably greater than 1.0.

[0011] The ratio of the sum of the second and third masses M2+M3 to the sum of the weight of the entire device including the electrical energy storage and the cutting disk is at least 0.45, preferably greater than 0.5.

[0012] This weight ratio provides a work tool with excellent stability and vibration damping performance while enabling efficient cutting operations.

[0013] Further advantages are obtained with the features recited in the dependent claims.

[0014] In general, all terms used in the claims should be interpreted according to their ordinary meaning in the art, unless otherwise specified herein. All references to "elements, apparatus, components, means, steps, etc." should be openly interpreted as referring to at least one instance of the element, apparatus, component, means, step, etc., unless otherwise specified. The steps of the methods disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. Further features and advantages of the present invention will become apparent upon review of the appended claims and the following description. Those skilled in the art will understand that different features of the present invention can be combined to create embodiments other than those described below, without departing from the scope of the present invention.

[0015] The present disclosure will now be described in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0016] [Figure 1] 1 shows examples of work tools. [Figure 2A] 1 shows a diagram of another exemplary power tool. [Figure 2B] 1 shows a diagram of another exemplary power tool. [Figure 2C] 1 shows a diagram of another exemplary power tool. [Figure 3A] FIG. 2 shows a diagram of a work tool support arm. [Figure 3B] FIG. 2 shows a diagram of a work tool support arm. [Figure 4] A bellows for guiding the air flow is shown. [Diagram 5] A bellows for guiding the air flow is shown. [Figure 6] A bellows for guiding the air flow is shown. [Figure 7A] 1 shows a schematic diagram of a locking mechanism. [Figure 7B] 1 shows a schematic diagram of a locking mechanism. [Figure 7C] 1 shows a schematic diagram of a locking mechanism. [Figure 8] 1 shows an example of a power tool having a battery lock mechanism. [Figure 9] 13A and 13B are schematic diagrams illustrating details of a battery locking mechanism. [Figure 10A] 1 shows a diagram of an exemplary work tool; [Figure 10B] 1 shows a diagram of an exemplary work tool; [Figure 10C] 1 shows a diagram of an exemplary work tool; [Figure 11] 1 shows a schematic representation of a fan. [Figure 12] 1 shows an example of a fan for a power tool. [Figure 13] 1 shows an example of a fan housing. [Figure 14A] 1 shows the working tool support arm in detail. [Figure 14B] 1 shows the working tool support arm in detail. [Figure 14C] 1 shows the working tool support arm in detail. [Figure 15] 1 shows a drive mechanism for driving a circular cutting accessory. [Figure 16A] 1 shows the rear handle section with water hose connection. [Figure 16B] Detail of the water hose connector. [Figure 16C] Detail of the water hose connector. [Figure 17A] Detail of the battery compartment is shown. [Figure 17B] Detail of the battery compartment is shown. [Figure 18A] 1 shows a battery for insertion into the battery compartment. [Figure 18B] 1 shows a battery for insertion into the battery compartment. [Figure 18C] 1 shows a battery for insertion into the battery compartment. [Figure 19] 1 shows a schematic representation of a cutting tool. [Figure 20] 4 shows details of the cutting tool. [Figure 21] 1 illustrates an exemplary damping member. [Figure 22] 4 illustrates another exemplary damping member. [Diagram 23] 1 illustrates the flow of cooling air through components of a cutting tool. [Figure 24] 3 shows a schematic diagram of the cooling air flow. [Diagram 25] 2 shows a schematic diagram of the mass distribution of a power tool; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the invention are shown. However, the present invention can be embodied in many different forms and should not be construed as being limited to the embodiments and aspects set forth herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout the description.

[0018] It should be understood that the invention is not limited to the embodiments described herein and shown in the drawings, but rather, those skilled in the art will recognize that many variations and modifications may be made within the scope of the appended claims.

[0019] Fig. 1 shows a hand-held power tool 100. The power tool 100 of Fig. 1 includes a rotatable circular cutting tool 130, although the techniques disclosed herein may be applied to other cutting tools such as chainsaws, core drills, etc. An electric motor 140 is arranged to drive the cutting tool. The motor is powered from an electrical energy storage device arranged to be held in a battery compartment 150.

[0020] Electric motors generate a significant amount of heat during operation. To prevent the motor from overheating, a fan 145 is arranged to be driven by the motor 140. The fan may be attached, for example, directly to the motor shaft or by some transmission device. The fan generates an airflow that moves heat away from the electric motor, thereby cooling the motor.

[0021] The power tool 100 is configured 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 vibrations in the handles and the trigger, as excessive vibrations can be uncomfortable for an operator using the power tool 100. Excessive vibrations can also reduce the life of tool components such as cabling and electronics. To reduce these vibrations, the power tool 100 comprises a first part 110 and a second part 120 arranged in vibrational isolation from each other. The first part 110 comprises an interface for holding a cutting accessory 130, and also comprises an electric motor 140 arranged to drive the cutting accessory. The first part therefore comprises the main vibration generating elements of the power tool.

[0022] In particular, the second portion 120 includes the handles 190, 195 and the trigger 196 and is thus the operator interface portion of the power tool 100. The second portion 120 also includes a battery compartment 150 for holding an electrical storage device and control electronics for controlling various operations of the power tool 100.

[0023] Since vibrations generated in the first portion 110 are not transmitted, or at least not to a significant extent, to the second portion 120, an operator of the device 100 is advantageously free from vibrations and can work for longer periods under more comfortable working conditions.

[0024] Vibrations are usually measured in m / s 2 The vibration of the tool is measured in units of 2.5 m / s2 at the front and rear handles. 2Tool vibrations, guidelines for limiting tool vibrations and their measurement are described in "VIBRATIONER - Arbetsmiljoverkets foreskrifter with vibrations samt allmanna rad om tillampningen av foreskrifterna", Arbetsmiljoverket, AFS 2005:15".

[0025] According to some embodiments, the power tool 100 may be configured to generate front and rear handle vibrations of 2.5 m / s 2 The device comprises a first part 110 and a second part 120 arranged in vibration isolation from each other by an isolation system arranged to limit a vibration amplitude of the first part 110 to a value less than 0.05 mm.

[0026] The cooling air conduit is arranged to direct a portion 160 of the cooling air flow from the first portion 110 to the second portion 120 for cooling the electrical storage device. This means that the fan 145 is used to cool both the electric motor 140 and the source of electrical energy, which has the advantage that only a single fan is required.

[0027] Here, a conduit is a passage arranged to direct a flow, such as a flow of air. The cooling air conduit may be formed as part of an interior space enclosed by the work tool body part, or as a hose of other types of conduits, or as a combination of different types of conduits.

[0028] Any control electronics included in the second part 120 may also be configured to be cooled by a portion 160 of the cooling air flow directed from the first part 110 to the second part 120. FIG. 1 shows a schematic cooling flange 180 associated with such control electronics. This cooling flange 180 is optional; that is, if the control unit constitutes a cooling flange, a portion of the cooling air flow can be used to directly cool the control unit. Thus, optionally, the portion 160 of the cooling air flow from the first part 110 to the second part 120 is arranged to pass through a cooling flange 180 associated with the control unit of the hand-held power tool 100.

[0029] At least in part because the first and second portions are positioned in vibrational isolation from one another, it may be difficult to efficiently direct the portion of air 160 from the first portion to the second portion. Some embodiments of the disclosed work tool solve this problem by providing bellows or other types of flexible air flow conduits between the first and second portions to direct the portion of air from the fan 145 toward the battery compartment 150. These bellows 170 are described in more detail below in connection with FIGS. 4-6. Bellows are sometimes referred to as flexible covers, convolutions, accordions, or machine way covers. A hose formed of a flexible material may be used instead of the bellows.

[0030] 1 shows a schematic representation of a hand-held power tool 100 comprising a first part 110 and a second part 120 arranged in vibrational isolation from one another. According to some embodiments, the first part 110 is vibrationally isolated from the second part 120 by one or more elastic elements.

[0031] The handheld power tool may be a cutting tool as shown in FIG. 1, but may also be a chainsaw or other power 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 may include, for example, a belt drive or a combination of a belt drive and a geared transmission. The electric motor 140 is configured to drive a fan 145 configured to generate a flow of cooling air for cooling the electric motor 140. The fan may, for example, be directly connected to the electric motor shaft or indirectly connected to the motor shaft via some transmission or drive, such as a belt drive or a geared transmission.

[0032] The second portion 120 includes 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 direct a portion 160 of the cooling air flow from the first portion 110 to the second portion 120 for cooling the electrical storage device. The source of electrical energy may be a battery, or some type of fuel battery, or the like.

[0033] 2A-2C show different views of an exemplary handheld power tool 200 arranged to hold a cutting accessory by a cutting accessory interface 260. The resilient element separating the first portion 110 from the second portion 120 is here a compression spring 210. However, as previously mentioned, some type of resilient material member, such as a rubber bushing, could be used in place of or in combination with the spring. A leaf spring could also be an option to vibrationally isolate the first portion 110 from the second portion 120.

[0034] FIG. 2B shows a holder 270 for an additional blade bushing. Cutting disks may have different dimensions with respect to the blade central hole. Some blade holes have a diameter of 20 mm, others 25.5 mm. In some markets, a blade central hole of 30.5 mm is common. To be able to use different types of blades with different dimensions in the central blade hole, the hand-held power tool 200 comprises a holder 270 arranged in the power tool body for holding a blade bushing. This additional blade bushing preferably has different dimensions compared to the blade bushing attached in connection with the cutting tool interface 260.

[0035] Figure 2A shows an exemplary electrical storage device 220, here a battery, attached to the battery compartment 150. The battery may be held in place by a battery locking mechanism, which is described in more detail below in connection with Figures 7A-7C, 8, and 9. Other types of electrical energy sources that may be used with the devices and techniques disclosed herein include, for example, fuel batteries, supercapacitors, and the like.

[0036] According to some embodiments, the flow of cooling air for cooling the electric motor 140 extends laterally 230, 245, 201 through the hand-held power tool relative to the extension plane of the circular cutting accessory 130. Now, referring to FIG. 2C, laterally should be interpreted relative to the extension direction 202 of the power tool extending from the rear handle 195 towards the cutting accessory, and relative to the extension plane of the cutting accessory 130 (which is more or less perpendicular in FIG. 2C). Air from the environment is drawn into the power tool interior via an air intake 230 on one side of the tool and is at least partially pushed laterally out of the power tool interior via a first air outlet 245 of the tool formed on the other side of the tool.

[0037] A portion of the airflow drawn into the work tool via the air inlet 230 is directed via an air conduit to the second portion 120 where it is used to cool the electrical storage device and optionally also a portion of the electrical control circuitry. For example, referring to Figure 2B, this portion of the airflow is directed downwardly from the fan and then rearwardly within the tool towards the battery compartment 150 before exiting the work tool via a second air outlet 250 formed in the second portion 120 of the tool.

[0038] It should be appreciated that if the fan is rotating in reverse, the air flow can also be directed in the opposite direction, i.e. the air outlets 245, 250 can also be used to draw cool air from the environment into the work tool 100, 200, and the air intake 230 can instead be repurposed to allow hot air to exit the work tool.

[0039] 10A , a portion 160 of the airflow that is directed downwardly from the fan and then rearwardly within the tool also exits the work tool through a third air outlet 251 formed in the battery compartment 150. This third outlet is primarily positioned for cooling the batteries received in the battery compartment 150.

[0040] 3A and 3B show some embodiments of the disclosed work tool, where the first portion 110 comprises a thermally conductive support arm 240 arranged to support a circular cutting tool 130 at a first end 241 of the support arm and an electric motor 140 by a support surface 330 at a second end 242 of the support arm opposite the first end 241. The motor 140 is then arranged to drive the cutting tool via some type of drive such as a belt drive or a combination of a belt drive and a geared transmission. The belt is not shown in FIG. 3A, only the belt pulley is shown. The support surface 330 represents a relatively large interface area between the motor 140 and the support arm 240, allowing a significant amount of heat transfer from the motor to the support arm material, at least if the electric motor includes a corresponding surface for interfacing with the support surface. This heat is then dissipated from one or more cooling flanges 320 formed on the support arm 240. Accordingly, the support arm 240 includes one or more cooling flanges 320 arranged to dissipate heat from the electric motor 140 via the support surface 330 .

[0041] The support arm 240 is the arm of a cutting tool and may equivalently be referred to as a cutoff arm 240 .

[0042] This heat transfer device improves heat dissipation from the motor as the cooling airflow is more efficiently utilized to move heat away from the motor.

[0043] The higher the thermal conductivity of the support arm, the more efficient the heat dissipation. According to some embodiments, at least some portions of the support arm are formed of a material having thermal conductivity properties of greater than 100 Watts per meter Kelvin (W / mK). For example, at least some portions of the support arm may be formed of aluminum, which has a thermal conductivity of about 237 W / mK. Iron or steel are other options that provide desirable thermal conductivity. The support arm may also be formed of a variety of materials; that is, one high thermal conductivity material, such as copper, magnesium, or aluminum, may be used for the cooling flange, while another material, such as cast iron or steel, may be used to provide general structural support.

[0044] Figures 14A-14C and 15 show details of an exemplary support arm 240 arranged to support a circular cutting tool 130 at a first end 241 of the support arm and an electric motor 140 by a support surface 330 at a second end 242 of the support arm opposite the first end 241. Figure 14A shows a view of said support arm 240 and interior space 340. Figure 14B shows a first cross-sectional view along line AA and Figure 14C shows a second cross-sectional view along line BB. The motor 140 comprises a motor shaft extending through a motor housing 141 in a known manner.

[0045] The first end 142 of the shaft is configured to carry a pulley for driving the circular cutting accessory 130. Figure 15 shows a view of the support arm 240 with the drive pulley and drive belt in place for driving the circular cutting accessory 130.

[0046] A second end 143 of the motor shaft is configured to drive a fan 145. The example of the fan 145 shown in Figure 14B is a conventional axial fan. Another, more advanced example of the fan 145 is discussed below in conjunction with Figures 11-13.

[0047] Optionally, the support arm 240 is configured to at least partially surround the electric motor 140, thereby protecting the motor and improving the cooling efficiency of the airflow 1330 passing through the motor. For this purpose, the support arm 240 comprises a cup-shaped recess seen in detail in FIG. 10C, with the support surface 330 constituting the bottom of the recess and a cylindrical wall 350 extending from the periphery of the support surface 330 and surrounding the motor housing 141 of the electric motor 140 when the motor is supported on the support surface 330. The motor 140 is arranged to be firmly bolted to the support surface 330 via bolt holes 335, thereby ensuring good thermal conduction as well as mechanical integrity between the motor 140 and the support arm 240. A slot is formed between the cylindrical wall 350 and the motor 140, i.e. the recess wall 350 is radially spaced from the motor housing. This slot is arranged to guide the cooling airflow 1330 from the fan 145 past the motor 140. Flow 1330 flows laterally from fan 145 through support arm 240 to cool electric motor 140. Flow 1330 of cooling air then passes through opening 310 into interior space 340 and then exits via first air outlet 245 shown in FIG.

[0048] According to some embodiments, at least 30% of the volume of the electric motor 140, i.e., the volume of the electric motor including its housing 141, is enclosed by the support arm 240. This means that the cylindrical wall 350 extends a distance 144 from the support surface 330 to enclose at least 30% of the volume of the motor housing 141. Thus, the motor is optionally mostly embedded in the support arm or fully embedded as shown in FIGS. 14A-14C. This improves the structural integrity of the motor and support arm assembly and improves heat transfer from the electric motor. Cooling of the electric motor 140 is also improved by slots formed between the cylindrical wall and the electric motor housing, which cooperate with the thermally conductive support arm and cooling flanges to efficiently cool the electric motor.

[0049] The support arm 240 and the electric motor 140 may also be at least partially integrally formed. This means that a portion of the electric motor 140 may be shared with the support arm 240. For example, a portion of the support arm 240 may form part of an electric motor housing, such as a motor gable that faces the support arm. The common portion shared between the support arm 240 and the electric motor 140 may be machined or molded, for example. Also, optionally, the electric motor shaft may support a surface of the support arm, improving mechanical integrity.

[0050] It should be noted that the feature of the at least partially integrally formed support arm and electric motor may be advantageously combined with other features disclosed herein, but is not dependent on any of the other features disclosed herein. Thus, disclosed herein is a support arm 240 and electric motor 140 assembly for a power tool 100, wherein the support arm and electric motor are at least partially integrally formed.

[0051] With reference to FIG. 2B, the first part 110 optionally comprises a belt guard 115 configured to enclose an interior space 340. As mentioned above, a part of the flow of cooling air is configured to be directed into the interior space 340, thereby raising the air pressure in the belt guard 115 interior space 340 above the ambient air pressure level. The interior space 340 is bounded on one side by a support arm (described below in connection with FIGS. 3A and 3B) and on the other side by the belt guard 115, which performs the function of a lid arranged to engage the support arm to protect, among other things, the drive belt. The belt guard 115 comprises an air outlet 245 through which the flow of cooling air leaves the interior space. This air outlet 245 is configured to have an area such that the air pressure in the belt guard 115 interior space 340 rises by a desired amount above the ambient air pressure level.

[0052] The increased air pressure within the interior space 340 means that the air flow will exit the interior space 340 through all openings, i.e., cracks, etc., not just the air outlets 245. This means that water, dust, debris, and slurry will have to overcome this air flow to get inside. This results in less buildup of debris within the work tool.

[0053] Water in the interior space 340 is undesirable as it can cause the belt drive to slip. Increased air pressure in the interior space 340 of the belt guard 115 means that less water can enter the interior space, which is an advantage. As a result, belt requirements can be reduced, for example, a belt with fewer ribs can be used.

[0054] As noted above, a portion 160 of the cooling air flow channeled from the first portion 110 to the second portion 120 may pass through a bellows or other flexible air flow conduit 170 disposed between the first portion 110 and the second portion 120. An example of such a bellows 10 is shown in detail in FIG.

[0055] According to some embodiments, the bellows 170 has a Shore hardness scale value, or Shore hardness, measured with a durometer type A according to DIN ISO 7619-1, between 10 and 70, preferably between 50 and 60.

[0056] Bellows 170 optionally includes a poka-yoke feature 410, 420. The poka-yoke feature includes at least one protrusion 410, 420 configured to receive a corresponding recess formed in first portion 110 and / or second portion 120, thereby preventing the bellows from being incorrectly assembled with first portion 110 and second portion 120.

[0057] Bellows 170 also optionally includes at least one edge 430, 440 of increased thickness. Each such edge is configured to enter a corresponding groove formed in first portion 110 or second portion 120, thereby securing bellows 170 relative to the first or second portion, similar to a sail leech that fits onto a mast. Figures 5 and 6 show diagrammatically the bellows attached by an edge to the first and second portions, respectively.

[0058] The bellows shown in Fig. 4 is constructed symmetrically about a plane of symmetry 450 parallel to the extension of edges 430, 440. Advantageously, the bellows can therefore be assembled with the first and second parts regardless of which side of the bellows is facing up, i.e. the bellows can be rotated 180 degrees about axis of symmetry 460 and assembled with the first and second parts.

[0059] 7A-7C show schematic diagrams of an embodiment of a battery compartment 150, in which the battery compartment includes a battery locking mechanism 700. The battery locking mechanism includes a locking member 710 rotatably supported on a shaft 720. The locking member includes a leading edge 750 arranged to receive a recess 760 formed in the source of electrical energy 220 to lock the source of electrical energy in place, the leading edge 750 having an arc shape corresponding to the curvature of a circle segment having a radius 740 corresponding to the distance from the leading edge 750 to the center of the shaft 720, and the recess 760 formed in the source of electrical energy 220 includes a surface 770 configured to engage the leading edge 750, the surface 770 having an arc shape matching the shape of the leading edge 750.

[0060] In this way, once the electrical energy source 220 is received in the battery compartment 150, the locking member is deactivated and simply follows the electrical energy source as it enters the compartment. This stage of inserting the electrical energy source 220 into the compartment 150 by moving the electrical energy source 220 in the insertion direction 701 is shown diagrammatically in Figures 7A and 7B. The locking member 710 then swings into a recess 760 which prevents the battery from being backed out of the battery compartment. The locked position is shown in Figure 7C. In particular, the arc shape of the leading edge 750 allows the locking mechanism to be rotated out of the locked position with less resistance, even if there is some friction between the leading edge 750 and a surface 770 arranged to engage the leading edge 750.

[0061] The locking member is spring biased towards a locked position and is operable by a lever or push button mechanism which is described below in connection with FIGS.

[0062] It will be appreciated that any number of locking members may be disposed in the battery compartment in the above manner, i.e., from a single locking member to multiple locking members.

[0063] According to some embodiments, the battery compartment 150 includes at least one resilient member 780 arranged to urge the electrical energy source into a locked position, i.e., to push the electrical energy source in a direction opposite to the direction of the insertion direction 701. When the resilient member 780 is compressed by the electrical energy source, it pushes the electrical energy source out of the battery compartment 150. This pushing force increases the contact pressure between the leading edge 750 and the surface 770 arranged to engage the leading edge 750, thereby improving the retention effect on the electrical energy source.

[0064] According to one example, a user inserts a battery into the battery compartment in an insertion direction. When the battery is fully inserted, it contacts the resilient member 780 and the locking member 710 enters a recess 760 formed in the electrical energy source 220, locking the electrical energy source in place. When the resilient member is compressed by the battery, it is pushed back in a direction opposite to the insertion direction. This pushing force from the resilient member increases the contact force between the front edge 750 of the locking member and the surface 770 configured to engage the front edge 750, more securely holding the battery in place.

[0065] The resilient member 780 optionally comprises any of a resilient material member, a compression spring, and / or a leaf spring.

[0066] The resilient member 708 also ejects the source of electrical energy 220 a short distance from the battery compartment 150 when the source of electrical energy is released by the locking mechanism 700. In this manner, when the push button mechanism 810 is operated to release the battery, the battery is ejected from the battery compartment 150 and the battery can be easily grasped and pulled from the battery compartment.

[0067] 7C shows a schematic example of such a resilient member 780. The resilient member urges the source of electrical energy in a direction 702, but the source of electrical energy is prevented from moving in this direction by the locking member 710 engaging the recess 760. The arrangement of the resilient member 780 and the locking member 710 on opposite sides S1, S2 of the source of electrical energy 220 creates a twisting motion 795 or rotational moment, which further increases the retention effect by increasing the friction between the battery and the battery compartment walls in a manner similar to stacked cupboards or desk drawers. This further improvement in retention reduces vibrations caused by the battery as it is held more snugly within the battery compartment.

[0068] 8 illustrates an exemplary power tool 800 including a battery locking mechanism 700. A locking member 710 is rotatably supported on a shaft 720 and can rotate about an axis of rotation 820. Using a push button mechanism 810, an operator can rotate the locking member 710 so that it exits the recess, thereby allowing the battery to be removed in a direction 702.

[0069] According to some embodiments, the locking member 710 is spring biased towards the locked position such that the locking member 710 snaps into the locked position when the source of electrical energy 220 is inserted into the recess 150. The spring bias can be overcome by the push button mechanism 810 when the source of electrical energy is removed from the battery compartment.

[0070] 9 shows details of the battery locking mechanism 700 of the battery compartment 150. This battery locking mechanism can be used with many different types of tools, such as abrasive tools, grinders, chainsaws, drills, cutting tools, etc. Thus, the battery locking mechanism disclosed herein is not limited to use with the cutting tools described above in connection with FIGS. 1-8.

[0071] The battery locking mechanism 700 shown in FIG. 9 comprises a locking member 710 rotatably supported on a shaft 720 and optionally spring-biased to a locked position as described above. The locking member has a leading edge 750 configured to enter a recess 760 formed in the electrical energy source 220 to lock the electrical energy source in place, as described above in connection with FIGS. 7A-7C. The leading edge 750 may have an arc shape with a curvature corresponding to a circle segment of a radius 740 corresponding to the distance from the leading edge 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 750. The surface 770 has an arc shape that coincides with the leading edge 750. In particular, the battery locking mechanism 700 shown in FIG. 9 comprises two locking members 710 separated by a distance. This dual arrangement of the locking members increases the robustness of the locking mechanism 700.

[0072] Thus, as described in relation to Figures 7A-7C, an electrical energy source such as a battery can be inserted in an insertion direction 701 into the battery compartment, i.e., into the compartment 150 shown in Figure 9. At some point, the locking member can enter a locked position, i.e., into the recess 760. In this position, the battery is prevented from moving in a direction 702 opposite to the insertion direction 701. However, it may be somewhat loose and may not be securely secured. To improve the battery locking mechanism and better hold the electrical energy source in place, one or more elastic members 780, such as compression springs or rubber bushings, are disposed on the battery compartment 150 and / or the electrical energy source to press against the electrical energy source as it is fully inserted into the compartment. The pressing force increases the contact force between the leading edge 750 and the surface 770 configured to engage the leading edge. This increased contact force increases friction, making it easier to hold the electrical energy source in place.

[0073] According to some embodiments, at least one resilient member 780 and the battery locking mechanism 700 are located on opposite sides S1, S2 of the battery compartment 150, i.e., there is a plane 910 that divides the battery compartment into two parts, with the resilient member 780 included in one part and the battery locking mechanism included in the other part. This means that the resilient member or members push the battery source from a certain direction, causing a twisting motion 795 or torque. This twisting motion can be likened to a drawer that hooks onto a cupboard or desk. The electrical energy source is prevented from rattling and is more firmly fixed in the battery compartment 150.

[0074] 10A and 10B show an exemplary work tool 1000 including a special type of fan 145. This fan comprises a member, preferably but not necessarily disk-shaped, located on the axis of the electric motor 140, which also constitutes the 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 sections. The first section acts as an axial fan, pushing the cooling air 201 laterally across the work tool 1000 to cool the electric motor 140. The second section of the fan acts as a radial fan, also called a centrifugal fan, and in cooperation with a fan scroll that matches the radial fan section, pushes the cooling air downwards to the second section of the work tool. The fan 145 is shown diagrammatically in FIG. 11 and an example of the fan is shown in FIG. 12, where the direction of rotation 1130 and the axis of rotation 1140 are shown. FIG. 11 also shows a direction 1145, called "radially outward" from the axis of rotation 1140.

[0075] 10A illustrates an example of a tool configured such that a portion 160 of the cooling air flow from the first portion 110 to the second portion 120 enters the electrical energy source 220 via a third outlet 251 disposed within the battery compartment 150, according to some embodiments. This connection to the electrical energy source improves cooling efficiency by improving cooling of cells, etc., within the battery.

[0076] The fan 145 comprises an axial fan portion 1110 disposed circumferentially around the periphery of the fan 145, i.e., circumferentially along the fan disk boundary as shown in Figures 11 and 12, and a radial fan portion 1120 disposed centrally of the fan 145, i.e., radially inward from the axial fan portion as shown in Figures 11 and 12. Thus, the axial fan portion is disposed radially outward 1145 in a plane of extension from the axis of rotation 1140. The axial fan portion 1110 is arranged to generate a flow of cooling air 1330 for cooling the electric motor 140, and the radial fan portion 1120 is arranged to generate a portion 160 of the flow of cooling air from the first portion 110 to the second portion 120 for cooling the electrical storage device.

[0077] Axial fans, or axial fans, have blades that force air to move parallel to the shaft or axis around which they rotate. This type of fan is used in a variety of applications, from small cooling fans for electronics to giant fans used in wind tunnels. Axial fans are particularly well-suited to creating large air flows in straight tubeline conduits, such as for cooling electric motors 140.

[0078] Radial, or centrifugal, fans increase the kinetic energy of the air / gas using centrifugal force provided by the rotation of the impeller. As the impeller rotates, gas particles near the impeller are expelled from the impeller and move to the wall of the fan housing. The gas is then directed to the outlet by the fan scroll. Compared to axial fans, radial fans are better at pushing cooling air through the pressure passing air duct with a narrow passage that curves as the air duct enters the second section and passes towards the battery compartment 150.

[0079] According to some aspects, the axial fan and the radial fan are formed as separate components mounted on the same motor shaft.

[0080] The radius of the radial fan may correspond to the radius of the electric motor gable.

[0081] The relationship between the radius of the radial fan and the radius of the fan may be on the order of 50 to 70 percent.

[0082] Advantageously, therefore, the fan shown in Figures 10 to 13 provides both efficient motor cooling and efficient cooling of the tool members in the second part, e.g. the control unit and the electrical energy source. This is achieved by providing two types of fans in one fan member.

[0083] 10C shows a more detailed view of a portion of the support arm including one or more cooling flanges 320 positioned to dissipate heat from the electric motor 140 via the support surface 330. Also visible are openings 310 for admitting air to the interior space 340 mentioned above. The axial fan portion 1110 pushes air through these holes past the motor, thereby cooling the electric motor 140.

[0084] The fan 145 may optionally be assembled into a fan housing 1010 illustrated in Figure 13. The fan housing includes at least one opening 1310 disposed circumferentially and radially outwardly of the axis of rotation 1140 for receiving a flow of cooling air 1330 from the axial fan portion 1110 for cooling the electric motor 140. The fan housing also includes a fan scroll 1320 disposed centrally in the housing and interfaces with the radial fan portion 1120 to direct a portion 160 of the flow of cooling air from the first portion 110 to the second portion 120 for cooling the electrical storage device.

[0085] FIG. 13 also shows groove 1340 and recess 1350 for receiving bellows 170 having edge 430 and poka-yoke feature 410 shown in FIG.

[0086] The fan described in relation to Figures 10A, 10B, 11, 12 and 13 is not only applicable to the type of work tool disclosed herein. On the contrary, the fan can be advantageously used in any type of work tool where a first flow and a second flow of cooling air are required. Thus, a fan 145 for a hand-held work tool 100, 200, 800, 1000 is disclosed herein. The fan 145 extends in a plane perpendicular to the axis of rotation 1140 of the fan. The fan comprises an axial fan portion 1110 arranged radially outward 145 from a radial fan portion 1120 centrally arranged on the fan 145 with respect to the axis of rotation 1140, the axial fan portion 1110 being configured to generate a first flow of cooling air for cooling a first hand-held work tool member, and the radial fan portion 1120 being configured to generate a second flow of cooling air 160 for cooling a second hand-held work tool member.

[0087] Optionally, axial fan section 1110 has an annular shape centered about an axis of rotation 1140 and radial fan section 1120 has a disk shape centered about axis of rotation 1140 .

[0088] Also disclosed herein is a hand-held power tool 1000 comprising a fan as described in relation to Figures 10-13 and a fan housing 1010. A fan 145 is assembled in the fan housing 1010, the fan housing being arranged at the periphery of the fan housing and comprising at least one opening 1310 arranged radially outward from a rotation axis 1140 of the fan 145 for receiving a first flow of cooling air from the axial fan section 1110 for cooling a first hand-held power tool member, and the fan housing also comprising a fan scroll 1320 arranged at the centre of the fan housing and interfacing with the radial fan section for directing a second flow of cooling air 160 for cooling a second hand-held power tool member.

[0089] FIG. 16A shows details of an optional connector arrangement 1600 for a water hose, preferably mounted near the rear handle 195 where an operator has easy access to attach and detach the water hose. The connector arrangement 1600 includes a water hose connector portion 1610, shown here as a nipple, i.e., connector male portion, for a water hose quick connector system facing rearward from the circular cutting tool 130. The connector nipple 1610 is fixedly attached to the machine housing by a bracket 1620 such that the water hose connector portion 1610 is held fixedly in relation to the work tool. Also, a female water hose connector portion can be fixedly attached to the work tool with a similar bracket to achieve the same technical effect and advantages. A water hose 1630 extends from the connector portion 1610 toward the cutting tool 130. The water hose 1630 is positioned at least partially recessed in the tool housing to protect the water hose from damage during use of the tool 100.

[0090] Known water hose connector configurations often include a segment of hose between a bracket on the work tool and a connector part (male or female connector part). This means that it is difficult to connect and disconnect the water hose with one hand. However, because the connector nipple 1610 is fixedly attached to the machine housing by the bracket 1620, the connector configuration 1600 allows for the attachment and removal of a water hose for supplying water to the cutting tool 130 with one hand during operation. The connector part is firmly supported by the machine housing in a location that is easy to access and does not move around. For example, an operator can hold the tool by the front handle 190 with one hand and connect the water hose with the other hand. The connector part 1610 can be adapted to interface with any quick connector system on the market, such as the Gardena® water hose system.

[0091] The water hose connector arrangement 1600, including the connector portion 1610 and the bracket 1620, may be implemented on any power tool requiring a supply of water and is not limited to the specific tools discussed herein.

[0092] Figures 16B and 16C show more detailed views of the connector arrangement 1600. Figure 16B is a view corresponding to Figure 16A, and Figure 16C shows the connector arrangement 1600 from an opposite perspective. The connector portion 1610 and bracket 1620 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 1640 for attaching a water hose 1630 may be located on the opposite side of the connector portion 1610 for convenient assembly of the connector arrangement on a hand-held power tool.

[0093] 17A and 17B show details of an exemplary battery compartment 150. 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, also shown in FIG. 9. FIG. 17A is a view opposite the insertion direction 701, and FIG. 17B is a view of the compartment 150 in the insertion direction 701. For example, the locking member 710 discussed above in relation to FIG. 9 can be seen in FIGS. 17A and 17B. The battery, discussed in more detail below in relation to FIGS. 18A-18C, optionally includes a rear surface shaped as a handle to simplify both the insertion and removal of the battery from the battery compartment 150.

[0094] Batteries for powering heavy-duty cutting tools such as the work tools described herein are typically very heavy. The batteries therefore need to be held in the battery housing 150 in a robust and reliable manner. To this end, the battery housing 150 is provided with a battery holding mechanism that is specially adapted to support heavy batteries, i.e. weights of the order of 5 kg, such as between 3 and 7 kg.

[0095] The battery compartment 150 extends laterally through the housing of the tool 100, 200, as discussed above, and defines a volume therein for receiving a battery. The volume is bounded by a rear wall Rw and a front wall Fw, with the rear wall Rw disposed toward the rear handle 195 of the tool 100 and the front wall Fw disposed toward the front of the tool 100, i.e., toward the cutting accessory 130. A bottom surface Bs and a top surface Fs also bound the volume. The example volume in Figures 17A and 17B is a rectangle with rounded corners.

[0096] The battery retention mechanism comprises a support heel 1710 located in a central portion of the side wall of the battery compartment, more specifically the rear wall Rw closest to the rear handle 195. The heel 1710 is elongated and extends laterally through the battery compartment, aligned with the insertion direction of the battery in the battery compartment 150. When the machine is resting on the ground support member 280, the support heel 1710 is parallel to the ground. Also, when the tool 100 is held in a normal operating position, the support heel is parallel to the ground, thereby supporting the battery against gravity. It will be understood that the support heel 1710 can also be located on the front wall, i.e., either the front wall and / or the rear wall of the battery compartment. The battery illustrated in Figures 18A-18C and described below is provided with a corresponding groove that matches the support heel.

[0097] According to some embodiments, the support heel 1710 has a metallic exterior for increased mechanical integrity, i.e., the support heel 1710 is optionally constructed with an outer metal layer for increased mechanical robustness.

[0098] According to some other embodiments, the battery compartment also includes an upper groove 1720 and a lower groove 1730 for supporting the battery within the battery compartment 150. The grooves are arranged to mate with corresponding raised structures on the battery, so that the battery can be inserted into the battery compartment 150 in an insertion direction 701 to a position that mates with the grooves. Thus, the support heel 1710 and the grooves 1720, 1730 cooperate to support the battery within the battery compartment in a safe and robust manner. The grooves 1720, 1730 function to guide the battery when it is inserted into the battery compartment 150 and prevent it from getting stuck when it is removed from the battery compartment 150.

[0099] Grooves 1720, 1730 are preferably formed as dovetail grooves.

[0100] According to some embodiments, the channels 1720, 1730 are metallized to increase their mechanical strength, i.e., the channels are reinforced with a metal lining layer to increase their mechanical robustness.

[0101] FIG. 17B also shows two resilient members 780 arranged to urge the battery into a locked position, i.e., to urge the source of electrical energy in a direction opposite to the direction of insertion direction 701, as discussed above in connection with FIG. 7C.

[0102] Contact strips 1740 extending in the insertion direction 701 are disposed in the battery compartment 150 to mate with corresponding electrical connectors arranged in the slots of the battery.

[0103] Also disclosed herein is a battery 1800 as shown in Figures 18A-18C for insertion into the battery compartment 150. The battery 1800 has a weight of 3-7 kg and comprises a groove 1810 disposed on one side of the battery to mate with a corresponding support heel 1710 disposed on the wall of the battery compartment 150. The groove optionally has an initial bevel to facilitate mating with the support heel 1710. The battery 1800 further comprises an upper raised structure 1820 and a lower raised structure 1830 on the opposite side of the battery compared to the groove 1810 to mate with corresponding grooves 1720, 1730 of the battery compartment 150 as shown in Figure 18. Thus, the battery 1800 is configured for insertion into the battery compartment 150 described in relation to Figures 17A and 17B.

[0104] Grooves 1720, 1730 are preferably formed as dovetail grooves.

[0105] The battery 1800 includes at least one recess 760 configured to receive a respective locking member 710 of the battery locking mechanism 700, as discussed above. The locking member includes an arcuate leading edge 750, and the recess 760 includes a surface 770 arranged to engage the leading edge 750. The surface 770 has an arcuate shape that matches the leading edge 750. As shown in FIG. 18A, two recesses are advantageously arranged on either side of the elongated support heel 1710.

[0106] The battery 1800 illustrated in Figures 18A-18C also includes one or more electrical connectors 1840 protectively positioned in slots extending in the insertion direction to mate with corresponding contact strips 1740 disposed in the battery compartment 150.

[0107] Optionally, the battery 1800 includes a front surface F1 that faces the insertion direction 701 when the battery 1800 is inserted into the battery compartment 150, and a back surface F2 opposite the front surface, the back surface being formed as a handle 1850 that can be gripped with one hand.

[0108] The battery also includes an electrical connector 1840 arranged in a slot extending in the insertion direction to mate with a corresponding contact strip 1740 arranged in the battery compartment 150. This protects the electrical connector from mechanical shock.

[0109] To facilitate cooling of the battery, as seen in Fig. 18C, there is an air inlet located on the underside of the battery in fluid communication with an air outlet 1860 located on the upper side of the battery. Thus, the airflow 160 from the fan 145 can be directed through the battery 1800 to better cool the battery cells.

[0110] The batteries and battery compartments described in connection with Figures 17 and 18 may be used in other hand held tools, and thus the features disclosed in connection with the battery compartment and battery are not dependent on any other specific features of the tools described herein.

[0111] FIG. 19 shows an exemplary handheld electric cutting tool 1900 comprising a first part 110 and a second part 120 arranged vibrationally isolated from each other by one or more damping members 170, 1910, optionally combined with one or more elastic members such as, for example, the metal springs 210 shown in FIG. 2A and FIG. 2C. As will be described in more detail below in connection with FIG. 25, the first part is associated with a first mass M1 and the second part is associated with a second mass M2. It is noteworthy that the ratio of the second mass M2 to the sum of the masses M1+M2 is much larger than is typical for, for example, a cutting tool powered by a combustion engine of similar size. This mass ratio improves the vibration isolation function of the first and second parts, stabilizing the cutting action and improving maneuverability during operation.

[0112] A potential problem with handheld cutting tools of the type discussed herein is that the cutting disc 130 becomes slightly elliptical during use. This is an undesirable situation as an overly elliptical cutting disc can impede cutting performance and cause discomfort to the operator. Elliptical cutting discs are associated with an increased risk of kickback, which is also undesirable. An example of an elliptical cutting disc 130 is shown in inset 1920 of FIG. 19. Elliptical cutting discs are associated with variations in the disc "diameters" D1, D2 measured on the disc. That is, D1 and D2 in FIG. 19 are not equal but differ by a non-negligible amount. While the measurements D1 and D2 may be considered as half of the semi-minor and semi-major axes of an ellipse, elliptical cutting discs are not perfectly elliptical and often have non-uniform radii along the circumference.

[0113] This problem with elliptical cutting discs tends to be more pronounced when the cutting disc angular velocity ω is low, such as when the cutting tool is operated below about 3600-4000 rpm, as measured at the axis of rotation of the cutting disc 130. Handheld power cutting tools that include vibrationally isolated first and second parts, such as the tools 100, 200, 800, 1000, 1900 discussed herein, may be particularly susceptible to the problem with elliptical cutting discs.

[0114] According to some embodiments, the handheld power cutting tools described herein, particularly in relation to Figures 19-22, are configured to operate at a cutting disk rotational speed ω of less than 4000 rpm, preferably about 3200 rpm.

[0115] A solution to the elliptical disc problem would be to simply increase the rotational speed ω of the cutting disc, for example to above 4000 rpm. However, such high cutting disc speeds are undesirable for a number of reasons.

[0116] For example, when cutting concrete or stone with a handheld power cutting tool without adding fluids such as water to the cutting zone, it is very difficult for the cutting disk to efficiently collect the dust generated by the cutting disk if the speed is too high, so it is desirable to reduce the speed of the cutting disk in dry cutting applications. Cutting disk speeds suitable for dry cutting applications are usually on the order of about 3100 to 3300 rpm, preferably about 3200 rpm. These speeds can be considered as maximum cutting speeds under normal dry cutting operating conditions.

[0117] A high cutting disc speed also means that the cutting disc stores a lot of energy during operation. This means that it becomes more difficult to apply the brakes and quickly reduce the cutting disc speed, for example during kickback. Therefore, for safety reasons, it may be desirable to limit the cutting disc speed to about 3100-3300 rpm, for example to about 3200 rpm.

[0118] Furthermore, power cutting tools may face challenges in generating sufficient torque for an efficient cutting action if the cutting disc speed is too high, so a cutting disc speed ω of around 3100-3300 rpm may be preferred.

[0119] It will be appreciated that the above cutting disc speeds are merely examples which depend on many aspects such as the type of tool, the size of the cutting disc, the specifications of the electric motor, etc. However, the general principles of high and low cutting disc speeds apply to most cutting tools.

[0120] It was recognized that the problem of elliptical cutting disks can be mitigated if damping members are arranged between the first and second parts 110 and 120 in combination with elastic members, optionally formed as metal springs, for efficient vibration isolation. These damping members are different from the usual spring-based vibration isolation elements typically used in this type of tool, since they are formed of a resilient material associated with a damping coefficient. The damping members dampen the vibration behavior between the two masses of the hand-held electric cutting tool, including the first and second parts, arranged in vibrational isolation from each other. This damping mitigates the tendency to form elliptical cutting blades at low cutting disk speeds. This is at least in part because, without the damping members, the two masses of a vibration-free cutting tool operating at a certain cutting disk speed may undergo vibrational motion that exerts different cutting pressures on different sections of the cutting blade. That is, the rotation of the cutting disk and the vibrational motion may be synchronized. When the system including the first and second parts 110 and 120 enters this type of vibrational state, an elliptical cutting disk may result.

[0121] Modern combustion engine-powered cutting tools are, as a rule, equipped with elastic members in the form of metal springs to suppress vibrations between the motor and the cutting disk parts, as well as some parts of the handle. However, these springs are not damping members in the sense that they suppress the oscillatory behavior of one mass relative to another. The relative harmonic motion between two masses can be approximated by the action of two masses connected by a spring, where the restoring force is directly proportional to the displacement of the two masses from their equilibrium position, according to Hooke's law. A system that follows simple harmonic motion is called a simple harmonic oscillator. This kind of oscillatory behavior can be reduced by adding a damping effect to the system. This can be achieved by adding a damping member associated with a damping coefficient (often denoted c) or a configuration that limits the stroke length of one part relative to the other. The damping ratio is a measure of how quickly the vibrations decay from one "bounce" to the next. Damping ratios can vary from undamped (ζ=0), underdamped (ζ<1) to critically damped (ζ=1) and overdamped (ζ>1). The addition of damping members to a mass-spring system affects the damping ratio.

[0122] FIG. 19, also with reference to FIG. 1, shows a handheld powered cutting tool 1900 including a first part 110 and a second part 120 arranged in vibrational isolation from each other. The first part 110 comprises an arm 116 arranged to support a cutting disk 130 (shown in inset 1920 of FIG. 19) and an electric motor 140 arranged to drive the cutting disk. The second part 120 comprises a front handle 190 and a rear handle 195 for operating the cutting tool, and a battery compartment 150 for holding an electrical storage device 220, 1800, such as a battery configured to power the electric motor 140. An example of this battery is described above in relation to FIGS. 18A-C.

[0123] In particular, one or more damping members 170, 1910 are disposed between the first portion 110 and the second portion 120, with at least one damping member 170, 1910 formed from a resilient material associated with a damping coefficient.

[0124] The damping member is arranged to dampen or impede vibration of the second part 120 relative to the first part 110. In this way, the risk of ending up with an oval shaped cutting disc is reduced.

[0125] According to an embodiment, at least one damping member 170, 1910 is made of rubber, elastic plastic material, closed-cell foam, or elastic synthetic resin. What these damping members have in common is that they introduce a damping coefficient into the resonance equation of the mechanical system including the first portion 110 and the second portion 120. This damping coefficient effectively suppresses the vibration behavior of the first portion relative to the second portion. For example, a closed-cell foam collar can be placed around the flexible airflow conduit 170 shown in FIG. 1, or a closed-cell foam collar can even constitute the flexible airflow conduit 170.

[0126] Preferably, since metal springs are more effective when it comes to vibrationally isolating parts from each other, the first part 110 is also vibrationally isolated from the second part 120 by one or more elastic elements 210 in addition to the at least one damping member 170. Here, the one or more elastic elements 210 include at least one metal spring. Thus, the combination of metal springs and damping members of elastic material provides both efficient vibration isolation and reduced risk of oval cutting discs during operation of the cutting tool.

[0127] 19 shows examples of two types of damping members that can be used independently or in combination. It should also be understood that the present teachings encompass other types of damping members applied elsewhere between the first and second portions. For example, between can also be interpreted to encompass a damping member that is attached to both the first and second portions but extends outside of the slot 1930 formed between the first and second portions.

[0128] FIG. 20 shows an example of two damping members 1910, 1920. The first damping member 170 is integrated with a bellows 2100 (shown in more detail in FIG. 21) or other flexible air flow conduit disposed between the first portion 110 and the second portion 120. The bellows or flexible air flow conduit provides a damping coefficient as described above to provide a desired damping ratio and also acts to limit the stroke length associated with the relative movement of the first portion 110 with respect to the second portion 120. As the first portion 110 moves towards the second portion 120 in direction C as shown in FIG. 21, a reinforcing element 1920 disposed on at least one side of the bellows, such as two or more sides of the bellows 2100, limits the compression of the bellows, thereby limiting the stroke length of the oscillatory motion and preventing oscillatory motion.

[0129] In order to obtain a desired damping ratio of the damped mass-spring system comprising the first and second parts, the compression factor associated with the Shore hardness of the bellows can be adjusted by selecting the type of material used in the reinforcing element 1920 or by dimensioning the thickness of the material used in the element and the bellows. The compression factor can also be adjusted by arranging one or more cavities 1930 in the reinforcing element 1920 as shown in FIG. 21. According to an embodiment, the bellows 2100 is arranged between the first part 110 and the second part 120, the bellows 2100 being associated with a Shore hardness value, or a Shore hardness, measured with a durometer type A according to DIN ISO 7619-1, between 50 and 100, preferably between 65 and 90. It will thus be appreciated that the Shore hardness and material thickness of the bellows as shown in FIG. 4 and / or FIG. 21 can be adjusted to mitigate the occurrence of oval cutting discs in hand-held power cutting tools by introducing a damping factor in the mass-spring system to suppress vibrations, or by introducing a stroke length limit to prevent vibrations, or both.

[0130] According to another example, also shown in FIG. 20, at least one damping member 1910 is fixedly attached to one of the first part 110 or the second part 120 and is arranged at a distance from the other of the first part 110 or the second part 120. The at least one damping member 1910 is thus arranged to limit the stroke length associated with the relative movement of the first part 110 with respect to the second part 120. This damping member has a similar function to the stiffening element 1920 previously described in relation to FIG. 21. It is arranged to limit the stroke length of the oscillatory movement between the first part and the second part, thus hindering the oscillatory behavior of the first part 110 with respect to the second part 120. A detailed view of the damping member 1910 is shown in FIG. 22. According to this example, it is integrally formed in a single elastic material and attached to the body of the first part 110 or the second part 120.

[0131] Alternatively, a damping member 1910 or some other resilient element can be attached to both the first portion 110 and the second portion 120 to form a resilient bridge between the parts. Since the damping member is related to the damping coefficient, the damping ratio of the damped mass-spring system can be affected by the addition of such a damping member to reduce the tendency for an oval cutting disc.

[0132] A low cutting disk speed that can be maintained without risk of an oval cutting disk allows an electric kickback protection mechanism to be advantageously implemented since kickback protection mechanisms based on braking by the electric motor 140 may be ineffective at very high cutting disk speeds. Thus, according to some embodiments, the electric motor 140 is configured to be controlled by a control unit of the cutting tool via a motor control interface. The control unit is configured to obtain data indicative of the angular velocity of the cutting disk 130 and detect a kickback condition based on a decrease in the angular velocity. The control unit is also configured to control an electromagnetic brake of the electric motor 140 in response to detecting the kickback condition.

[0133] Disclosed herein is a handheld electric cut-off tool for cutting concrete and stone with a rotatable cutting disk 130 to provide a kickback mitigation function that is fast enough to respond and has sufficient braking power, even for powerful cutting tools associated with significant tool inertia. The cutting tool comprises an electric motor 140 arranged to be controlled by a control unit via a motor control interface. The control unit is configured to obtain data indicative of the angular velocity of the cutting disk 130 and to detect a kickback condition based on a decrease in the angular velocity. The control unit is also configured to control an electromagnetic brake of the electric motor 140 in response to detecting the kickback condition, and optionally to actively regulate energy draw from the electric motor via the control interface during electromagnetic braking.

[0134] The detection mechanism is based on monitoring the angular velocity of the cutting disc 130. If there is a sudden speed reduction, such as a significant retardation of the electric rotor angle or the cutting disc angle, a kickback condition is detected. Immediately after the control unit detects the kickback event, the electric motor is forcefully braked to mitigate the effects of the kickback event. This braking actively controls the energy release from the electric motor to provide a strong braking force without damaging the electrical components of the cutting tool. This braking is facilitated by the fact that the cutting disc operates at a speed below 3500 rpm, e.g. 3200 rpm, which is made possible by the presence of a damping member.

[0135] Kickback detection and braking of the cutting disc is often fast enough to stop the blade before it leaves the workpiece. If a kickback action does occur, the energy transferred from the cutting disc 130 to the machine body is reduced to a level that mitigates the adverse effects of the kickback event. Notably, the electric motor is not simply disconnected from the power source, as in many prior art documents. Rather, the intake of energy from the electric motor is actively adjusted to provide a braking action strong enough to stop the kickback event.

[0136] 23 shows a handheld powered cutting tool 2300 including a fan 145 configured to be driven by an electric motor 140 to generate a cooling air flow 160, and an electrical storage device 220, 1800, such as a battery, configured to power the electric motor 140. The cooling air conduit is arranged to guide the cooling air flow 160 towards an outlet opening 1750 (seen, for example, in FIG. 17B) formed in a wall of the battery compartment 150. The outlet opening 1750 faces a corresponding inlet opening 1870 formed in a housing of the electrical storage device 220, 1800 to receive the cooling air and thereby generate an air pressure above atmospheric pressure within the electrical storage device 220, 1800. Referring to FIG. 24, which illustrates the cooling flow more diagrammatically, a first slot section Ss1 is formed by the distance between the outlet opening 1750 and the inlet opening 1870 of the electrical storage device 220, such that a first portion 2415 of the cooling air flow 160 leaks out of the cutting tool through the first slot section Ss1.

[0137] This first portion 2415 of the cooling air flow 160 creates air pressure in the first slot section that dirt and slurry entering the slot between the electrical storage device 220 and the compartment wall must overcome. This has the advantage of preventing dirt and slurry from entering the slot and keeping the battery compartment clean. A clean battery compartment free of dirt and slurry makes it easier to move the electrical storage device 220 in and out of the tool.

[0138] The first portion 2415 of the cooling air flow is directed transversely to the general flow 160 of cooling air entering the electrical storage device 220, 1800. Additionally, leakage may occur on both sides of the cutting tool, i.e., on both sides of the battery compartment perforation.

[0139] According to one example, the first slot section Ss1 is delimited on one side by a guide means for guiding the electrical storage device 220 into the housing. The first slot section Ss1 may also be delimited by a support heel 1710. However, the slot sections Ss1, Ss2, Ss3 may be interconnected or delimited by other delimitations.

[0140] According to an embodiment, the distance between the electrical storage device 220, 1800 and the walls of the battery compartment 150 is between 0.5 mm and 2.0 mm, preferably about 1.0 mm. This distance may vary around the perimeter of the electrical storage device 220.

[0141] The electrical storage device 220, 1800 may further comprise one or more electrical connectors 1840 arranged to mate with corresponding contact strips 1740 arranged on the battery compartment 150. Examples of these electrical connectors are shown more clearly in FIG. 18C. An opening in the housing of the electrical storage device 220, 1800 is formed in connection with the electrical connector 1840, and a second portion 2425 of the cooling air flow passes through the opening and escapes to the exterior of the cutting tool through a second slot section Ss2 formed between the electrical storage device 220, 1800 and the wall of the battery compartment 150. Thus, since the battery housing is not sealed around the electrical connector 1840, overpressure of the cooling air in the electrical storage device 220 creates an air flow that exits through the electrical connector and passes through the second slot section. Again, any dirt or slurry attempting to enter the slot must overcome this air flow to exit the machine through the slot. This is unlikely to occur as the leakage is a significant flow compared to the more diffuse movement of dust and slurry created by the cutting operation. Thus, the electrical connector remains clean and free of slurry during operation, which is an advantage in that it is easier to insert and remove the electrical storage device 220, especially when the connector and guide means are clean. The second slot section Ss2 may be bounded, for example, by an upper raised structure 1820 and a lower raised structure 1830 as shown in FIG. 18C.

[0142] Finally, an air outlet 1860 may also be formed in the housing of the electrical storage device opposite the inlet opening 1870 to provide a passage for cooling air to flow through the electrical storage device. A third slot section Ss3 may be formed by a distance between the air outlet 1860 and the wall of the battery compartment 150 to allow a third portion 2435 of the cooling air flow 160 to leak out of the cutting tool via the third slot section Ss3. This third slot section also provides a passage for the cooling air to leak out via the slot, thereby keeping the space between the top of the electrical storage device 220 and the battery compartment wall clean and free of dust and slurry.

[0143] Figure 25 shows diagrammatically the mass distribution of a working tool such as the cutting tool described above in relation to Figures 1 to 24. It has been found that the weight distribution between the parts of a hand-held electric cutting tool comprising a first part and a second part arranged in vibrational isolation from each other can be optimized in order to achieve a more efficient cutting operation and at the same time reduce discomfort to the operator due to vibrations transmitted from the machine via the handle to the operator.

[0144] Vibration-isolated gasoline-fueled cutting tools, i.e. tools powered by a combustion engine, are known. However, these known tools have a non-optimal weight distribution between the handle and the part constituting the combustion engine and the cutting disc. Some known gasoline-fueled cutting machines have a motor and arm weight of about 7550 g, whereas the handle weight is about 2600 g with an empty fuel tank and about 3500 g with a full tank, resulting in a ratio of 2600 g / 10150 g (about 0.25) with an empty tank and 3500 g / 11050 g (about 0.32) with a full tank. The ratio with a full tank can be compared to the case where a battery (mass M3) is attached to mass M2, i.e. M2+M3, and the case with an empty tank can be compared to the case where there is no battery, i.e. only M2.

[0145] It is advantageous if certain parts of the handle, i.e. masses M2 and M3 in Fig. 25, are heavy enough to withstand the vibrations propagating through the damping and elastic elements mentioned above. However, certain parts of the cutting blade, i.e. masses M1 and M4, cannot be too light in relation to the handle parts, as this would cause the tool to become unbalanced.

[0146] Through extensive experiments and computer analysis, it has been found that the ratio of the second mass M2 to the sum of the first and second masses M1+M2 should preferably be at least 0.3, preferably greater than 0.35, i.e. the second mass should represent a significant portion of the total mass of the cutting tool without the cutting disk and the electrical storage device attached. The ratio M2 / (M1+M2) is, for example, about 0.38 for a 12-inch blade device and about 0.37 for a 14-inch blade device. However, the second mass M2 should not be too large relative to the first mass. Thus, the ratio of the second mass M2 to the sum of the first and second masses M1+M2 should preferably be less than about 0.5, preferably less than about 0.6.

[0147] It has also been found that the ratio of the sum of the second and third masses (i.e. M2+M3) to the sum of the first and fourth masses (M1+M4) should be at least 0.6, preferably greater than 0.8, and even more preferably greater than 1.0. These ratios provide a balanced tool with good vibration isolation capabilities.

[0148] It has also been found that the ratio of the sum of the second and third masses (M2+M3) to the sum of the weight of the entire device including the electrical energy storage and the cutting disk (i.e. M1+M2+M3+M4) should be at least 0.45 and preferably greater than 0.5. This ratio provides a stable tool with good anti-vibration properties.

[0149] In summary, disclosed herein are handheld power cutting tools 100, 200, 800, 1000, 1900, 2500 including a first portion 110 and a second portion 120 arranged in vibrational isolation from one another; The first portion 110 includes an interface 2510 for holding the cutting accessory 130 and an electric motor 140 configured to drive the cutting accessory, the first portion being associated with a first mass M1; The second portion 120 comprises a battery compartment 150 for holding an electrical storage device 220 configured to power the electric motor 140, and a front handle 190 and a rear handle 195 for manipulating the cutting tool, the second portion being associated with a second mass M2, wherein a ratio of the second mass M2 to the sum of the first and second masses M1+M2 is at least 0.3, preferably greater than 0.35.

[0150] A handheld electric cutting tool 100, 200, 800, 1000, 1900, 2500 is disclosed, which comprises a first part 110 and a second part 120, a cutting tool 130 and an electric storage device 220 arranged in a vibrationally isolated manner from each other; The first portion 110 includes an interface 2510 for holding the cutting accessory 130 and an electric motor 140 configured to drive the cutting accessory, the first portion being associated with a first mass M1, the cutting accessory being associated with a fourth mass M4, The second portion 120 comprises a battery compartment 150 for holding an electrical storage device 220 configured to power the electric motor 140, and a front handle 190 and a rear handle 195 for manipulating the cutting tool, the second portion being associated with a second mass M2, the electrical storage device 220 being associated with a third mass M3, The ratio of the sum of the second and third masses M2+M3 to the sum of the first and fourth masses M1+M4 is at least 0.6, preferably greater than 0.8, and even more preferably greater than 1.0.

[0151] Further disclosed are handheld electric cutting tools 100, 200, 800, 1000, 1900, 2500 comprising a first part 110 and a second part 120, a cutting tool 130 and an electric storage device 220 arranged in vibrational isolation from each other, The first portion 110 includes an interface 2510 for holding the cutting accessory 130 and an electric motor 140 configured to drive the cutting accessory, the first portion being associated with a first mass M1, the cutting accessory being associated with a fourth mass M4, The second portion 120 comprises a battery compartment 150 for holding an electrical storage device 220 configured to power the electric motor 140, and a front handle 190 and a rear handle 195 for manipulating the cutting tool, the second portion being associated with a second mass M2, the electrical storage device 220 being associated with a third mass M3, The ratio of the sum of the second and third masses (M2+M3) to the sum of the weight of the entire device including the electrical energy storage and the cutting disk (M1+M2+M3+M4) is at least 0.45, preferably greater than 0.5.

[0152] The following table provides an exemplary weight distribution that may be advantageously used with the handheld power cutting tools discussed herein. Two different size battery examples are included in the table, with a larger battery weighing approximately 5100g (labeled M32) and a smaller battery weighing approximately 3000g (labeled M31).

[0153] [Table 1] [Explanation of symbols]

[0154] 100,200,800,1000,1900 Handheld electric cutting tools 110 First Part 115 Belt Guard 116 Arm 120 Second Part 130 Circular cutting tool 140 Electric Motor 141 Motor housing 145 Fans 150 Battery compartment 160 Part of the cooling air 170 Bellows, flexible air flow conduit 180 Cooling flange 190 Front Handle 195 Rear Handle 210 Elastic member 220 Electricity storage device 240 Support Arm 245,250,251 Air outlet 260 Cutting Tool Interface 270 Holder 280 Ground Support Members 310 Opening 320 Cooling flange 330 Support surface 335 Bolt Hole 340 Interior Space 350 Cylindrical Wall 410,420 Pokayoke function, protrusion 701 Insertion direction 708 Elastic Members 710 Locking member 750 leading edge 760 Recess 770 surface 780 Elastic Members 1010 Fan Housing 1110 Axial fan part 1120 Radial fan part 1320 Fun Scroll 1600 Connector Configuration 1610 Connector part 1620 Bracket 1630 Water hose 1710 Support Heel 1720 Upper Groove 1730 Lower Groove 1740 Contact Strip 1800 Electric storage device, battery 1820 Upper raised structure 1830 Lower raised structure 1840 Electrical Connector 1850 Handle 1910,1920 Damping material

Claims

1. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) comprising a first part (110) and a second part (120) arranged in vibrational isolation from each other at least in part by an elastic element, the first portion (110) comprises an interface (2510) for holding a cutting accessory (130) and an electric motor (140) configured to drive the cutting accessory, the first portion having a first mass (M1); the second portion (120) comprises a battery compartment (150) for holding an electrical storage device (220) configured to power the electric motor (140), and a front handle (190) and a rear handle (195) for manipulating the cutting tool, the second portion having a second mass (M2); A hand-held power cutting tool (100, 200, 800, 1000, 1900, 2500), wherein the ratio of the second mass (M2) to the sum of the first and second masses (M1+M2) is at least 0.3, and preferably greater than 0.

35.

2. A handheld electric cutting tool (100, 200, 800, 1000, 1900, 2500) as claimed in claim 1, wherein the electrical storage device (220) is a battery (1800), the battery (1800) configured to be inserted into a battery storage section (150) of the handheld cutting tool, the battery (1800) having a weight of 3 kg to 7 kg and comprising a groove (1810) arranged on one side of the battery to mate with a corresponding support heel (1710) arranged on a wall of the battery storage section (150), the battery further comprising an upper raised structure (1820) and a lower raised structure (1830) arranged on an opposite side of the battery compared to the groove (1810), the raised structures configured to mate with corresponding grooves (1720, 1730) of the battery storage section (150).

3. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) according to claim 1 or 2, wherein the first mass (M1) is between 4000g and 5000g.

4. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) according to any one of claims 1 to 3, wherein the second mass (M2) is between 2500g and 3500g.

5. The hand held power cutting tool (100, 200, 800, 1000, 1900, 2500) of any one of claims 1 to 4, wherein the raised structures are configured to fit into corresponding grooves (1720, 1730) in the battery compartment (150).

6. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) comprising a first part (110) and a second part (120) arranged to be at least partially vibrationally isolated from each other by an elastic element, a cutting tool (130), and an electrical storage device (220), the first portion (110) comprises an interface (2510) for holding the cutting accessory (130) and an electric motor (140) configured to drive the cutting accessory, the first portion having a first mass (M1), the cutting accessory having a fourth mass (M4); the second part (120) comprises a battery compartment (150) for holding the electrical storage device (220) configured to power the electric motor (140), and a front handle (190) and a rear handle (195) for manipulating the cutting tool, the second part having a second mass (M2), the electrical storage device (220) having a third mass (M3); A hand-held power cutting tool (100, 200, 800, 1000, 1900, 2500), wherein the ratio of the sum of the second and third masses (M2+M3) to the sum of the first and fourth masses (M1+M4) is at least 0.6, preferably greater than 0.8, and even more preferably greater than 1.

0.

7. A handheld electric cutting tool (100, 200, 800, 1000, 1900, 2500) as described in claim 6, wherein the electrical storage device (220) is a battery (1800), the battery (1800) is configured to be inserted into a battery storage section (150) of the handheld cutting tool, the battery (1800) having a weight of 3 kg to 7 kg and comprising a groove (1810) arranged on one side of the battery to mate with a corresponding support heel (1710) arranged on a wall of the battery storage section (150), the battery further comprising an upper raised structure (1820) and a lower raised structure (1830) arranged on an opposite side of the battery compared to the groove (1810), the raised structures being configured to mate with corresponding grooves (1720, 1730) of the battery storage section (150).

8. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) according to claim 6 or 7, wherein the first mass (M1) is between 4000g and 5000g.

9. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) according to any one of claims 6 to 8, wherein the second mass (M2) is between 2500g and 3500g.

10. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) comprising a first part (110) and a second part (120) arranged in vibrational isolation from each other at least in part by an elastic element, a cutting tool (130), and an electrical storage device (220), the first portion (110) comprises an interface (2510) for holding the cutting accessory (130) and an electric motor (140) configured to drive the cutting accessory, the first portion having a first mass (M1), the cutting accessory having a fourth mass (M4); the second part (120) comprises a battery compartment (150) for holding the electrical storage device (220) configured to power the electric motor (140), and a front handle (190) and a rear handle (195) for manipulating the cutting tool, the second part having a second mass (M2), the electrical storage device (220) having a third mass (M3); A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500), wherein the ratio of the sum of the second and third masses (M2+M3) to the sum of the weight of the entire device including the electrical storage device (220) and the cutting accessory (130) is at least 0.45, preferably greater than 0.

5.

11. A handheld electric cutting tool (100, 200, 800, 1000, 1900, 2500) as described in claim 10, wherein the electrical storage device (220) is a battery (1800), the battery (1800) is configured to be inserted into a battery compartment (150) of the handheld cutting tool, the battery (1800) having a weight of 3 kg to 7 kg and comprising a groove (1810) arranged on one side of the battery to mate with a corresponding support heel (1710) arranged on a wall of the battery compartment (150), the battery further comprising an upper raised structure (1820) and a lower raised structure (1830) arranged on an opposite side of the battery compared to the groove (1810), the raised structures being configured to mate with corresponding grooves (1720, 1730) of the battery compartment (150).

12. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) according to claim 10 or 11, wherein the first mass (M1) is between 4000g and 5000g.

13. A hand-held electric cutting tool (100, 200, 800, 1000, 1900, 2500) according to any one of claims 10 to 12, wherein the second mass (M2) is between 2500g and 3500g.

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