Handheld power tools

Abstract

A handheld power cutting tool (100, 200, 800, 1000, 1900) comprising a first part (110) and a second part (120) arranged in vibrational isolation from each other, The first portion (110) comprises an arm (116) configured to support a cutting disc (130) and an electric motor (140) configured to drive the cutting disc; The second portion (120) comprises a front handle (190) and a rear handle (195) for manipulating 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); One or more damping members (170, 1910) are disposed between the first portion (110) and the second portion (120), and at least one damping member (170, 1910) is formed from a resilient material associated with a damping coefficient.

Description

[Technical Field]

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

[0002] Handheld work tools for cutting and / or grinding hard materials such as concrete and stone have powerful motors to provide the power necessary to process the hard materials. These motors generate significant heat and must 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] Power tools typically 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 tool's performance. For example, slurry can accumulate inside the work tool and ultimately cause tool failure. It is desirable to prevent dust and slurry from accumulating inside the work tool.

[0005] Ease of operation is particularly important for work tools used on construction sites. For electric work tools, it is desirable that the battery be easy to insert into the work tool, that the battery be securely held in the work tool, that the battery be easily released from the work tool, and that battery replacement in the field be efficient and convenient.

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

[0007] SUMMARY OF THE INVENTION It is an object of the present disclosure to provide an improved handheld power tool that addresses the above-mentioned 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 comprises an arm configured to support a cutting disc and an electric motor configured to drive the cutting disc. The second part comprises front and rear handles for operating the cutting tool and a battery compartment for holding an electrical storage device, such as a battery, configured to power the electric motor. In particular, one or more damping members are arranged between the first and second parts, at least one damping member being formed of an elastic material associated with a damping coefficient.

[0009] In this way, the tendency to produce an oval cutting disc during operation is reduced.Further advantages are obtained by the dependent claims set forth herein.

[0010] The primary vibration-generating portion of the power tool is comprised of the first section. Therefore, by vibrationally isolating the first section from the second section, the amount of vibration transmitted to the second section is significantly reduced. The second section may include, for example, the front and rear handles, which are vibrationally isolated from the vibration source of the first section. Because vibration is reduced, the operator can use the tool longer and more comfortably.

[0011] Further advantages are obtained with the features recited in the dependent claims.

[0012] 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 methods disclosed herein need not 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.

[0013] The present disclosure will now be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0014] [Figure 1] Examples of work tools are shown below. [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] 1 shows a view of a work tool support arm. [Figure 3B] 1 shows a view of a work tool support arm. [Figure 4] 1 shows a bellows for guiding air flow. [Figure 5] 1 shows a bellows for guiding air flow. [Figure 6] 1 shows a bellows for guiding air flow. [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] 10 shows a schematic diagram of the battery lock mechanism in detail. [Figure 10A] 1 shows a diagram of an exemplary power tool; [Figure 10B] 1 shows a diagram of an exemplary power tool; [Figure 10C] 1 shows a diagram of an exemplary power tool; [Figure 11] 1 shows a schematic representation of a fan. [Figure 12] An example of a power tool fan is shown. [Figure 13] 1 shows an example of a fan housing. [Figure 14A] 1 shows details of the work tool support arm. [Figure 14B] 1 shows details of the work tool support arm. [Figure 14C] 1 shows details of the work tool support arm. [Figure 15] 1 shows a drive mechanism for driving a circular cutting tool. [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] 1 shows details of a cutting tool. [Figure 21] 1 illustrates an exemplary damping member. [Figure 22] 1 illustrates another exemplary damping member. [Figure 23] 1 illustrates the flow of cooling air through components of a cutting tool. [Figure 24] 1 shows a schematic representation of the flow of cooling air. [Figure 25] 1 shows a schematic representation of the mass distribution of a power tool; DETAILED DESCRIPTION OF THE INVENTION

[0015] 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 may 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 as examples 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 reference numerals refer to like elements throughout the description.

[0016] It should be understood that the present 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.

[0017] Figure 1 shows a handheld power tool 100. The power tool 100 of Figure 1 includes a rotatable circular cutting tool 130, although the techniques disclosed herein can also 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 by an electrical energy storage device arranged to be held in a battery compartment 150.

[0018] 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 type of transmission. The fan generates an airflow that moves heat away from the electric motor, thereby cooling the motor.

[0019] 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. Because excessive vibrations can be uncomfortable for an operator using the power tool 100, it is desirable to minimize handle and trigger vibrations. Excessive vibrations can also shorten the life of tool components such as cabling and electronics. To reduce these vibrations, the power tool 100 includes a first portion 110 and a second portion 120 that are vibrationally isolated from each other. The first portion 110 includes an interface for holding a cutting accessory 130 and an electric motor 140 arranged to drive the cutting accessory. Thus, the first portion comprises the primary vibration-generating elements of the power tool.

[0020] In particular, second portion 120 includes handles 190, 195 and trigger 196 and is therefore the operator-interfacing portion of power tool 100. Second portion 120 also includes a battery compartment 150 for holding an electrical storage device and control electronics for controlling various operations of power tool 100.

[0021] 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.

[0022] Vibrations are usually measured in m / s 2 Measured in units of 2.5 m / s and limits tool vibration at the front and rear handles 2Tool vibrations, guidelines for limiting tool vibrations and their measurement are explained in "VIBRATIONER - Arbetsmiljoverkets foreskrifter om vibrationer samt allmanna rad om tillampningen av foreskrifterna", Arbetsmiljoverket, AFS 2005:15.

[0023] 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 the vibration of the first part (110) to a value less than 1 / 2 mm.

[0024] 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 electrical energy source, which has the advantage that only a single fan is required.

[0025] Here, a conduit is a passage arranged to conduct a flow, such as a flow of air. The cooling air conduit may be formed as part of an interior space enclosed by a work tool body part, as a hose of other types of conduit, or as a combination of different types of conduit.

[0026] Any control electronics included in the second portion 120 may also be configured to be cooled by a portion 160 of the cooling air flow directed from the first portion 110 to the second portion 120. FIG. 1 schematically shows a cooling flange 180 associated with such control electronics. This cooling flange 180 is optional; that is, if the control unit comprises 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 portion 110 to the second portion 120 is arranged to pass through the cooling flange 180 associated with the control unit of the handheld power tool 100.

[0027] At least in part because the first and second sections are vibrationally isolated from one another, it may be difficult to efficiently direct the portion of air 160 from the first section to the second section. Some embodiments of the disclosed power tool address this issue by providing a bellows or other type of flexible airflow conduit between the first and second sections to direct a portion of the 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 also be used instead of the bellows.

[0028] 1 schematically illustrates a hand-held power tool 100 comprising a first portion 110 and a second portion 120 arranged in vibrational isolation from one another. According to some embodiments, the first portion 110 is vibrationally isolated from the second portion 120 by one or more elastic elements.

[0029] The handheld power tool may be a cutting tool, as shown in FIG. 1 , or may be a chainsaw or other power tool for cutting hard materials. The first portion includes 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 be directly connected to the electric motor shaft, for example, or indirectly connected to the motor shaft via some kind of transmission or drive, such as a belt drive or a geared transmission.

[0030] 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.

[0031] 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 for vibrationally isolating the first portion 110 from the second portion 120.

[0032] FIG. 2B shows a holder 270 for an additional blade bushing. Cutting discs may have different dimensions with respect to the central blade hole. Some blade holes have a diameter of 20 mm, while others have a diameter of 25.5 mm. In some markets, a 30.5 mm central blade hole is common. To accommodate use with different types of blades having different central blade hole dimensions, the handheld power tool 200 includes a holder 270 disposed on the power tool body for holding a blade bushing. This additional blade bushing preferably has different dimensions compared to the blade bushing attached to the cutting tool interface 260.

[0033] 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 FIGS. 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, etc.

[0034] 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 plane of extension of the circular cutting accessory 130. Referring now to Figure 2C, laterality should be interpreted relative to the direction of extension 202 of the power tool, which extends from the rear handle 195 toward the cutting accessory, and relative to the plane of extension of the cutting accessory 130 (which is more or less perpendicular in Figure 2C). Air from the environment is drawn into the power tool interior through an air intake 230 on one side of the tool and is at least partially forced laterally out of the air intake 230 and out of the power tool interior via a first air outlet 245 of the tool formed on the other side of the tool.

[0035] A portion of the airflow drawn into the work tool through the air inlet 230 is directed through an air conduit to the second portion 120, where it is used to cool the electrical storage device and, optionally, a portion of the electrical control circuitry. For example, referring to Figure 2B, this portion of the airflow is directed downward from the fan and then rearward within the tool towards the battery compartment 150 before exiting the work tool through a second air outlet 250 formed in the second portion 120 of the tool.

[0036] 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.

[0037] 10A, a portion 160 of the airflow that is directed downward from the fan and then rearward within the tool also exits the power tool through a third air outlet 251 formed in the battery compartment 150. This third outlet is primarily positioned to cool the battery received in the battery compartment 150.

[0038] 3A and 3B illustrate several embodiments of the disclosed power tool, including a first portion 110 including a thermally conductive support arm 240 positioned to support a circular cutting tool 130 at a first end 241 of the support arm and an electric motor 140 via a support surface 330 at a second end 242 of the support arm opposite the first end 241. The motor 140 is then positioned 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 for 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 through 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 .

[0039] The support arm 240 is the arm of the cutting tool and may equivalently be referred to as the cutoff arm 240 .

[0040] 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.

[0041] 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 from a material having thermal conductivity properties greater than 100 Watts per meter-Kelvin (W / mK). For example, at least some portions of the support arm may be formed from aluminum, which has a thermal conductivity of approximately 237 W / mK. Iron or steel are other options that provide desirable thermal conductivity. The support arm may also be formed from 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.

[0042] 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 the 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 includes a motor shaft extending through a motor housing 141 in a known manner.

[0043] The first end 142 of the shaft is configured to carry a pulley for driving the circular cutting tool 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 tool 130.

[0044] 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 connection with Figures 11-13.

[0045] 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. To this end, the support arm 240 includes a cup-shaped recess, seen in detail in FIG. 10C , where the support surface 330 forms the bottom of the recess and the cylindrical wall 350 extends from the periphery of the support surface 330 and surrounds the motor housing 141 of the electric motor 140 when the motor is supported on the support surface 330. The motor 140 is positioned to be securely bolted to the support surface 330 via bolt holes 335, thereby ensuring good thermal conduction and 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. The slot is positioned 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. Cooling air flow 1330 then passes through opening 310 into interior space 340 and then exits via first air outlet 245 shown in FIG. 2B.

[0046] 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 largely embedded in the support arm, or completely 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, in cooperation with the thermally conductive support arm and cooling flange, efficiently cool the electric motor.

[0047] 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 the electric motor housing, such as a motor gable facing the support arm. The common portion shared between the support arm 240 and the electric motor 140 may be machined or molded, for example. Optionally, the electric motor shaft may also support a surface of the support arm, improving mechanical integrity.

[0048] It should be noted that the feature of the at least partially integrally formed support arm and electric motor may be advantageously combined with, 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.

[0049] Referring to FIG. 2B , the first portion 110 optionally includes a belt guard 115 configured to enclose an interior space 340. As described above, a portion of the cooling air flow is configured to be directed into the interior space 340, thereby increasing the air pressure within 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 functions as a lid positioned to engage the support arm to protect, among other things, the drive belt. The belt guard 115 includes an air outlet 245 through which the cooling air flow exits the interior space. The air outlet 245 is configured to have a region such that the air pressure within the belt guard 115 interior space 340 increases above the ambient air pressure level by a desired amount.

[0050] The increased air pressure within the interior space 340 means that air flow will exit the interior space 340 not only through the air outlet 245 but through all openings, i.e., cracks, etc. This means that water, dust, debris, and slurry must overcome this air flow to enter the interior, thereby reducing the buildup of debris within the work tool.

[0051] Water in the interior space 340 is undesirable because 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.

[0052] As noted above, a portion 160 of the cooling air flow channeled from first portion 110 to second portion 120 may pass through a bellows or other flexible air flow conduit 170 disposed between first portion 110 and second portion 120. An example of such a bellows 10 is shown in detail in FIG.

[0053] According to some embodiments, the bellows 170 has a Shore hardness scale value, or Shore hardness, between 10 and 70, preferably between 50 and 60, measured with a durometer type A according to DIN ISO 7619-1.

[0054] Bellows 170 optionally includes poka-yoke features 410, 420. The poka-yoke features include at least one protrusion 410, 420 configured to fit into 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.

[0055] Bellows 170 also optionally includes at least one thickened edge 430, 440. Each such edge is configured to fit into 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 fitting to a mast. Figures 5 and 6 schematically show bellows attached by an edge to the first and second portions, respectively.

[0056] 4 is symmetrical 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. That is, the bellows can be rotated 180 degrees about axis of symmetry 460 and assembled with the first and second parts.

[0057] 7A-7C schematically illustrate 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 positioned to receive a recess 760 formed in the electrical energy source 220 to lock the electrical energy source 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 energy source 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.

[0058] In this manner, 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 FIGS. 7A and 7B. The locking member 710 then swings into a recess 760 that prevents the battery from being withdrawn from the battery compartment. The locked position is shown in FIG. 7C. Notably, the arcuate shape of the leading edge 750 allows the locking mechanism to rotate out of the locked position with less resistance, even if there is some friction between the leading edge 750 and the surface 770 that is positioned to engage the leading edge 750.

[0059] The locking member is spring biased towards a locked position and is operable by a lever or push button mechanism described below in connection with FIGS.

[0060] It will be appreciated that any number of locking members may be arranged in the battery compartment in the above manner, i.e., from a single locking member to multiple locking members.

[0061] 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 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.

[0062] 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 pushes 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 with the front edge 750, more securely holding the battery in place.

[0063] The resilient member 780 optionally comprises any of a resilient material member, a compression spring, and / or a leaf spring.

[0064] The resilient member 708 also ejects 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. 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 can be easily grasped and pulled out of the battery compartment.

[0065] 7C schematically illustrates an example of such a resilient member 780. The resilient member urges the source of electrical energy in 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 cupboard or desk drawers. This further improvement in retention reduces vibration caused by the battery because it is more snugly held within the battery compartment.

[0066] 8 shows 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 direction 702.

[0067] According to some embodiments, the locking member 710 is spring biased toward the locked position such that the locking member 710 snaps into the locked position when the electrical energy source 220 is inserted into the recess 150. The spring bias can be overcome by the push button mechanism 810 when the electrical energy source is removed from the battery compartment.

[0068] 9 shows details of the battery locking mechanism 700 of the battery compartment 150. This battery locking mechanism can be used with a variety of tools, such as abrasive tools, grinders, chainsaws, drills, cutting tools, etc. Thus, the battery locking mechanisms disclosed herein are not limited to use with the cutting tools described above in connection with FIGS. 1-8.

[0069] The battery locking mechanism 700 shown in FIG. 9 includes 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 receive 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 arcuate shape with a curvature corresponding to a circle segment with 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 includes a surface 770 positioned to engage the leading edge 750. The surface 770 has an arcuate shape that matches the leading edge 750. Notably, the battery locking mechanism 700 shown in FIG. 9 includes two locking members 710 separated by a distance. This dual arrangement of the locking members improves the robustness of the locking mechanism 700.

[0070] 7A-7C , an electrical energy source, such as a battery, can be inserted into the battery compartment 150 shown in FIG. 9 in an insertion direction 701. 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 the insertion direction 701. However, there may be some looseness and the battery may not be securely fastened. To improve the battery locking mechanism and better hold the electrical energy source in place, one or more resilient 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 when 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.

[0071] According to some embodiments, at least one resilient member 780 and battery locking mechanism 700 are located on opposite sides S1, S2 of the battery compartment 150; i.e., there is a plane 910 dividing the battery compartment into two sections, with the resilient member 780 included in one section and the battery locking mechanism included in the other section. This means that one or more resilient 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 hooking into a cupboard or desk. The electrical energy source is prevented from rattling and is more securely secured in the battery compartment 150.

[0072] FIGS. 10A and 10B show an exemplary power tool 1000 that includes a special type of fan 145. The fan comprises a preferably, but not necessarily, disk-shaped member located on the shaft of the electric motor 140, which also constitutes the fan's axis of rotation. The member extends in a plane perpendicular to the axis of rotation and includes two different types of fan sections. The first section functions as an axial fan, pushing cooling air 201 laterally across the power tool 1000 to cool the electric motor 140. The second section of the fan functions as a radial fan, also known as a centrifugal fan, and works in conjunction with a fan scroll that matches the radial fan section to push cooling air downward and into the second section of the power tool. The fan 145 is shown schematically in FIG. 11, and an example of the fan is shown in FIG. 12, where the direction of rotation 1130 and axis of rotation 1140 are indicated. FIG. 11 also shows a direction 1145, referred to as "radially outward," from the axis of rotation 1140.

[0073] 10A illustrates an example of a tool configured such that a portion 160 of the cooling air flow from first portion 110 to second portion 120 enters electrical energy source 220 via a third outlet 251 disposed within 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.

[0074] Fan 145 comprises an axial fan section 1110 disposed circumferentially around the periphery of fan 145, i.e., circumferentially along the fan disk boundary as shown in Figures 11 and 12, and a radial fan section 1120 disposed centrally around fan 145, i.e., radially inward from the axial fan section as shown in Figures 11 and 12. Thus, the axial fan section is disposed radially outward 1145 in a plane of elongation from axis of rotation 1140. Axial fan section 1110 is positioned to generate cooling air flow 1330 for cooling electric motor 140, and radial fan section 1120 is positioned to generate a portion 160 of cooling air flow from first section 110 to second section 120 for cooling an electrical storage device.

[0075] Axial fans, or axial fans, have blades that force air to move parallel to the shaft 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 for generating large airflows in straight tubeline conduits, such as those used to cool electric motors 140.

[0076] 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 toward 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 superior at pushing cooling air through the pressure-passing air duct, which has a narrow, curved passage as the air duct enters the second section and passes toward the battery compartment 150.

[0077] According to some aspects, the axial fan and radial fan are formed as separate components mounted on the same motor shaft.

[0078] The radius of the radial fan may correspond to the radius of the electric motor gable.

[0079] The relationship between the radius of the radial fan and the radius of the fan can be on the order of 50 to 70 percent.

[0080] 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 portion, e.g., the control unit and the electrical energy source, by providing two types of fans in one fan member.

[0081] 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. An axial fan portion 1110 pushes air past the motor and through these holes, thereby cooling the electric motor 140.

[0082] Fan 145 may optionally be assembled in a fan housing 1010, illustrated in Figure 13. The fan housing includes at least one opening 1310 located circumferentially and radially outward of rotational axis 1140 for receiving a flow of cooling air 1330 from axial fan section 1110 for cooling electric motor 140. The fan housing also includes a fan scroll 1320 located centrally therein and interfaces with radial fan section 1120 to direct a portion 160 of the flow of cooling air from first section 110 to second section 120 for cooling the electrical storage device.

[0083] FIG. 13 also shows groove 1340 and recess 1350 for receiving bellows 170 having edge 430 and poka-yoke feature 410 shown in FIG.

[0084] The fan described in connection with Figures 10A, 10B, 11, 12, and 13 is not only applicable to the power tools of the type disclosed herein. Rather, the fan can be advantageously used with any type of power tool requiring a first and second flow of cooling air. Accordingly, a fan 145 for a hand-held power tool 100, 200, 800, or 1000 is disclosed herein. The fan 145 extends in a plane perpendicular to the fan's axis of rotation 1140. The fan includes an axial fan portion 1110 disposed radially outward 145 from a radial fan portion 1120 centrally disposed on the fan 145 relative to the axis of rotation 1140. The axial fan portion 1110 is configured to generate a first flow of cooling air for cooling a first hand-held power tool member, and the radial fan portion 1120 is configured to generate a second flow of cooling air 160 for cooling a second hand-held power tool member.

[0085] Optionally, axial fan section 1110 has an annular shape centered on axis of rotation 1140 and radial fan section 1120 has a disc shape centered on axis of rotation 1140 .

[0086] Also disclosed herein is a hand-held power tool 1000 including the fan described in connection with Figures 10-13 and a fan housing 1010. The fan 145 is assembled within the fan housing 1010, the fan housing being arranged at the periphery of the fan housing and including at least one opening 1310 arranged radially outward from the rotation axis 1140 of the fan 145 to receive a first flow of cooling air from the axial fan section 1110 for cooling a first hand-held power tool, and the fan housing also including a fan scroll 1320 arranged centrally within the fan housing and interfacing with the radial fan section for guiding a second flow of cooling air 160 for cooling a second hand-held power tool member.

[0087] FIG. 16A shows details of an optional connector arrangement 1600 for a water hose, preferably mounted near the rear handle 195 where an operator can easily access it for attaching and detaching the water hose. The connector arrangement 1600 includes a water hose connector portion 1610, shown here as a nipple, i.e., male connector 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 so that the water hose connector portion 1610 is fixedly held in relation to the work tool. Alternatively, 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.

[0088] Known water hose connector configurations often include a hose segment between a bracket on the work tool and a connector portion (male or female connector portion). This means that connecting and disconnecting the water hose with one hand is difficult. 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 detachment of a water hose to supply water to the cutting tool 130 with one hand during operation. The connector portion 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. The connector portion 1610 can be adapted to interface with any quick connector system on the market, such as the Gardena® water hose system.

[0089] The water hose connector arrangement 1600, including the connector portion 1610 and the bracket 1620, can be implemented on any power tool requiring a supply of water and is not limited to the specific tools discussed herein.

[0090] Figures 16B and 16C show more detailed views of connector configuration 1600. Figure 16B is a view corresponding to Figure 16A, and Figure 16C shows connector configuration 1600 from an opposite perspective. Connector portion 1610 and bracket 1620 are preferably integrally formed, i.e., machined or molded from a single 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 connector portion 1610 for convenient assembly of the connector configuration on a handheld power tool.

[0091] 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 150 in an insertion direction 701, i.e., 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 as seen in the insertion direction 701. For example, the locking member 710 discussed above in connection with FIG. 9 can be seen in FIGS. 17A and 17B. The battery, discussed in more detail below in connection with 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.

[0092] Batteries for powering heavy-duty cutting tools, such as the power tools described herein, are typically very heavy. Therefore, the batteries need to be held in a robust and reliable manner in the battery compartment 150. To this end, the battery compartment 150 is provided with a battery holding mechanism that is specially adapted to support heavy batteries, i.e., weights on the order of 5 kg, such as between 3 and 7 kg.

[0093] The battery compartment 150, as discussed above, extends laterally through the housing of the tool 100, 200 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.

[0094] The battery retention mechanism includes a support heel 1710 located in a central portion of the side wall of the battery compartment, more specifically, on the rear wall Rw closest to the rear handle 195. The heel 1710 is elongated, extending laterally through the battery compartment 150 in alignment with the insertion direction of the battery into the battery compartment 150. When the machine rests on the ground support member 280, the support heel 1710 is parallel to the ground. Furthermore, when the tool 100 is held in its 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., on either the front and / or rear wall of the battery compartment. The batteries illustrated in FIGS. 18A-18C and described below include corresponding grooves that match the support heels.

[0095] 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.

[0096] 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 positioned to mate with corresponding raised structures on the battery, allowing the battery to be inserted into the battery compartment 150 in the insertion direction 701 into 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 secure manner. The grooves 1720, 1730 function to guide the battery when it is inserted into the battery compartment 150 and prevent the battery from getting caught when it is removed from the battery compartment 150.

[0097] Grooves 1720, 1730 are preferably formed as dovetail grooves.

[0098] According to some embodiments, the grooves 1720, 1730 are metallized to provide increased mechanical strength, i.e., the grooves are reinforced with a metal lining layer to provide increased mechanical robustness.

[0099] FIG. 17B also shows two resilient members 780 arranged to push the battery into a locked position, i.e., to push the source of electrical energy in a direction opposite to the direction of insertion direction 701, as discussed above in connection with FIG. 7C.

[0100] Contact strips 1740 extending in the insertion direction 701 are disposed in the battery compartment 150 to mate with corresponding electrical connectors arranged in slots on the battery.

[0101] Also disclosed herein is a battery 1800, as shown in FIGS. 18A-18C, for insertion into the battery compartment 150. The battery 1800 has a weight of 3-7 kg and includes 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 includes 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 in the battery compartment 150, as shown in FIG. 18. Thus, the battery 1800 is configured for insertion into the battery compartment 150 described in connection with FIGS. 17A and 17B.

[0102] Grooves 1720, 1730 are preferably formed as dovetail grooves.

[0103] 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 positioned 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 positioned on opposite sides of the elongated support heel 1710.

[0104] 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 positioned in the battery compartment 150.

[0105] 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.

[0106] The battery also includes an electrical connector 1840 configured in a slot extending in the insertion direction to mate with a corresponding contact strip 1740 located in the battery compartment 150. This protects the electrical connector from mechanical shock.

[0107] To facilitate cooling of the battery, as seen in Figure 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, airflow 160 from fan 145 can be directed through battery 1800 to better cool the battery cells.

[0108] 17 and 18 may be used with other hand-held tools, and therefore the features disclosed with respect to the battery compartment and battery are not dependent on any other specific features of the tool described herein.

[0109] FIG. 19 illustrates an exemplary handheld power cutting tool 1900 including a first portion 110 and a second portion 120 arranged to be vibrationally isolated from one another by one or more damping members 170, 1910, optionally in combination with one or more resilient members, such as, for example, the metal spring 210 shown in FIGS. 2A and 2C. As described in more detail below in connection with FIG. 25, the first portion is associated with a first mass M1, and the second portion is associated with a second mass M2. Notably, the ratio of the second mass M2 to the sum of the masses M1+M2 is much greater than, for example, a typical ratio for a similarly sized combustion engine-powered cutting tool. This mass ratio improves the vibration isolation of the first and second portions, stabilizing the cutting action and improving maneuverability during operation.

[0110] A potential problem with handheld cutting tools of the type discussed herein is that the cutting disc 130 may become slightly oval during use. This is undesirable because an overly oval cutting disc can impede cutting performance and potentially cause discomfort to the operator. Oval cutting discs are associated with an increased risk of kickback, which is also undesirable. An example of an oval cutting disc 130 is shown in inset 1920 of FIG. 19. Oval cutting discs are associated with variations in the disc "diameters" D1 and D2 measured on the disc. That is, D1 and D2 in FIG. 19 are not equal but differ by a non-negligible amount. While measurements D1 and D2 may be considered half of the semi-minor and semi-major axes of an ellipse, oval cutting discs are not perfectly elliptical and often have non-uniform radii along their circumference.

[0111] This problem with oval cutting discs tends to be more pronounced when the cutting disc angular velocity w 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, and 1900 discussed herein, may be particularly susceptible to the problem of oval cutting discs.

[0112] According to some embodiments, the handheld power cutting tools described herein, particularly in connection with Figures 19-22, are configured to operate at a cutting disk rotational speed w of less than 4000 rpm, preferably about 3200 rpm.

[0113] A solution to the oval disc problem is to simply increase the rotational speed w of the cutting disc, for example to above 4000 rpm. However, such high cutting disc speeds are undesirable for a number of reasons.

[0114] 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 cutting disk speed in dry cutting applications. Cutting disk speeds suitable for dry cutting applications are typically on the order of about 3100 to 3300 rpm, preferably about 3200 rpm. These speeds can be considered maximum cutting speeds under normal dry cutting operating conditions.

[0115] A high cutting disc speed also means that the cutting disc stores more energy during operation. This means that it is more difficult to quickly slow down the cutting disc by braking, for example during kickback. Therefore, for safety reasons, it may be desirable to limit the cutting disc speed to approximately 3100-3300 rpm, for example, approximately 3200 rpm.

[0116] Furthermore, power cutting tools may face challenges in generating sufficient torque for efficient cutting if the cutting disc speed is too high, so a cutting disc speed w of approximately 3100-3300 rpm may be preferred.

[0117] It will be appreciated that the above cutting disc speeds are merely examples which will 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.

[0118] It has been recognized that the problem of oval cutting discs can be mitigated when a damping member is disposed between the first and second sections 110 and 120, optionally in combination with a resilient member formed as a metal spring for efficient vibration isolation. These damping members are formed from a resilient material with an associated damping coefficient, making them different from the typical spring-based vibration isolation elements typically used in this type of tool. The damping member damps vibration behavior between two masses of a handheld power cutting tool, including a first and second section, positioned in vibration isolation from each other. This damping reduces the tendency for oval cutting blades to form at low cutting disc speeds. This is at least in part because, without the damping member, two masses of a vibration-free cutting tool operating at a particular cutting disc speed may vibrate in a way that exerts different cutting pressures on different sections of the cutting blade. In other words, the vibrational motion may synchronize with the rotation of the cutting disc. When the system including the first and second sections 110 and 120 enters this type of vibrational state, oval cutting discs may result.

[0119] Modern combustion-engine-powered cutting tools typically include elastic elements in the form of metal springs to damp vibrations between the motor and cutting disk, as well as certain parts of the handle. However, these springs are not damping elements in the sense that they damp 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, with the restoring force being directly proportional to the displacement of the two masses from their equilibrium positions, according to Hooke's law. A system that follows simple harmonic motion is called a simple harmonic oscillator. This type of oscillatory behavior can be reduced by adding a damping effect to the system. This can be achieved by adding a damping element associated with a damping coefficient (often denoted c) or a mechanism that limits the stroke length of one part relative to the other. The damping ratio is a measure of how quickly the vibration decays from one "bounce" to the next. Damping ratios range from undamped (ζ = 0), underdamped (ζ < 1), critically damped (ζ = 1), to overdamped (ζ > 1). The addition of damping members to a mass-spring system affects the damping ratio.

[0120] FIG. 19, also referring to FIG. 1, shows a handheld power cutting tool 1900 including a first portion 110 and a second portion 120 arranged in vibrational isolation from one another. The first portion 110 includes 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 portion 120 includes 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. Examples of such batteries are described above in connection with FIGS. 18A-18C.

[0121] 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.

[0122] 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 cutting disc is reduced.

[0123] According to embodiments, at least one damping member 170, 1910 is made of rubber, a resilient plastic material, closed-cell foam, or a resilient 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 disposed around the flexible airflow conduit 170 shown in FIG. 1 , or the closed-cell foam collar can even constitute the flexible airflow conduit 170.

[0124] Preferably, because metal springs are more effective when it comes to vibrationally isolating parts from one another, the first portion 110 is also vibrationally isolated from the second portion 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 a metal spring and a damping member of elastic material provides both efficient vibration isolation and a reduced risk of oval cutting discs during operation of the cutting tool.

[0125] 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 attached to both the first and second portions but extending outside of slot 1930 formed between the first and second portions.

[0126] 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 airflow conduit disposed between the first portion 110 and the second portion 120. The bellows or flexible airflow conduit provides a damping coefficient as described above to provide a desired damping ratio and also acts to limit the stroke length associated with relative movement of the first portion 110 with respect to the second portion 120. As the first portion 110 moves toward 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 compression of the bellows, thereby limiting the stroke length of the oscillatory motion and preventing oscillatory action.

[0127] To obtain a desired damping ratio for the damped mass-spring system comprising the first and second portions, the compression factor, related to 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 disposing one or more cavities 1930 in the reinforcing element 1920, as shown in FIG. 21 . According to an embodiment, the bellows 2100 is disposed between the first portion 110 and the second portion 120, and the bellows 2100 is associated with a Shore hardness value, or 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 handheld power cutting tools by introducing a damping factor into the mass-spring system to suppress vibrations, introducing a stroke length limit to prevent vibrations, or both.

[0128] According to another example, as 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 spaced apart 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 described above in connection with FIG. 21 . It is arranged to limit the stroke length of the oscillatory movement between the first and second parts, thus preventing 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 from a single elastic material and attached to the body of the first part 110 or the second part 120.

[0129] Alternatively, a damping member 1910 or some other elastic element can be attached to both the first portion 110 and the second portion 120 to form an elastic bridge between the parts. Because 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, reducing the tendency for an oval cutting disc.

[0130] The low cutting disk speeds that can be maintained without risk of an oval cutting disk allow for advantageous implementation of an electric kickback protection mechanism, 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 a kickback condition.

[0131] Disclosed herein is a handheld power cut-off tool for cutting concrete and stone with a rotatable cutting disc 130 to provide a kickback mitigation function with sufficiently fast response and sufficient braking force, even for powerful cutting tools associated with significant tool inertia. The cutting tool includes 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 disc 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, and optionally actively adjust energy draw from the electric motor via the control interface during electromagnetic braking.

[0132] The detection mechanism is based on monitoring the angular velocity of the cutting disc 130. A kickback condition is detected when a sudden decrease in speed, such as a significant retardation in the electric rotor angle or cutting disc angle, is detected. Immediately after the control unit detects a kickback event, the electric motor is forcibly braked to mitigate the effects of the kickback event. This braking actively controls the energy release from the electric motor to provide a powerful braking force without damaging the cutting tool's electrical components. This braking is facilitated by the fact that the cutting disc operates at speeds below 3500 rpm, e.g., 3200 rpm, which is made possible by the presence of a damping element.

[0133] Kickback detection and braking of the cutting disc is often fast enough to stop the blade before it leaves the workpiece. Even if a kickback occurs, 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 energy intake from the electric motor is actively adjusted to provide a braking action powerful enough to stop the kickback event.

[0134] 1, FIG. 23 shows a handheld power cutting tool 2300 including a fan 145 configured to be driven by the electric motor 140 to generate a flow of cooling air 160, and an electrical storage device 220, 1800, such as a battery, configured to power the electric motor 140. The cooling air conduit is positioned to guide the flow of cooling air 160 toward 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 the housing of the electrical storage device 220, 1800 to receive the cooling air and thereby generate above-atmospheric air pressure within the electrical storage device 220, 1800. Referring to FIG. 24, which shows the cooling flow more schematically, 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.

[0135] This first portion 2415 of the cooling air flow 160 creates air pressure within 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, keeping the battery compartment clean. A clean battery compartment that is free of dirt and slurry buildup makes it easier to move the electrical storage device 220 in and out of the tool.

[0136] 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 can occur on both sides of the cutting tool, i.e., on both sides of the battery compartment through-hole.

[0137] According to one example, the first slot section Ss1 is delimited on one side by a guide means that guides the electrical storage device 220 into the storage portion. 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 delimiters.

[0138] According to an embodiment, the distance between the electrical storage device 220, 1800 and the wall 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.

[0139] The electrical storage device 220, 1800 may further include 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 more clearly shown in FIG. 18C . An opening in the housing of the electrical storage device 220, 1800 is formed in connection with the electrical connector 1840, allowing a second portion 2425 of the cooling air flow to leak through the opening and out of the cutting tool via a second slot section Ss2 formed between the electrical storage device 220, 1800 and the wall of the battery compartment 150. Thus, because the battery housing is not sealed around the electrical connector 1840, overpressure of the cooling air within the electrical storage device 220 generates 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 because the leakage is a significant flow compared to the more diffuse movement of dust and slurry generated by the cutting operation. Therefore, 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 delimited, for example, by an upper raised structure 1820 and a lower raised structure 1830 as shown in FIG. 18C.

[0140] Finally, an air outlet 1860 may also be formed in the electrical storage device housing opposite the inlet opening 1870 to provide a passageway for cooling air to flow through the electrical storage device. A third slot section Ss3 may be formed by the 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 through the third slot section Ss3. This third slot section also provides a passageway for the cooling air to leak out through 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.

[0141] Figure 25 shows a schematic diagram of the mass distribution of a power 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 handheld power cutting tool having a first part and a second part arranged in vibrational isolation from each other can be optimized to achieve a more efficient cutting operation while at the same time reducing discomfort to the operator due to vibrations transmitted from the machine through the handle to the operator.

[0142] Vibration-isolated gasoline-fueled cutting tools, i.e., tools powered by a combustion engine, are known. However, these known tools do not have an optimal weight distribution between the handle and the components comprising the combustion engine and cutting disc. Some known gasoline-fueled cutting machines have a motor and arm weighing approximately 7550 g, while the handle weighs approximately 2600 g with an empty fuel tank and approximately 3500 g with a full tank, resulting in a ratio of 2600 g / 10150 g (approximately 0.25) with an empty tank and 3500 g / 11050 g (approximately 0.32) with a full tank. The full tank ratio can be compared to a battery (mass M3) attached to mass M2, i.e., M2+M3, while the empty tank ratio can be compared to a battery-less, i.e., M2 alone.

[0143] It is advantageous if certain parts of the handle, i.e. masses M2 and M3 in Figure 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 relative to the handle, as this would unbalance the tool.

[0144] Through extensive experimentation 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 account for a significant portion of the total mass of the cutting tool without the cutting disk and electrical storage device attached. For example, the ratio M2 / (M1+M2) is approximately 0.38 for a 12-inch blade device and approximately 0.37 for a 14-inch blade device. However, the second mass M2 should not be too large relative to the first mass. Therefore, the ratio of the second mass M2 to the sum of the first and second masses M1+M2 should preferably be less than approximately 0.5, preferably less than approximately 0.6.

[0145] 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 excellent vibration isolation capabilities.

[0146] They also found that the ratio of the sum of the second and third masses (M2+M3) to the total weight of the entire device, including the electrical energy storage and 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 vibration isolation properties.

[0147] 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; First portion 110 includes 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 comprises a battery compartment 150 for holding an electrical storage device 220 configured to power the electric motor 140, 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 the 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.

[0148] Disclosed are handheld power cutting tools 100, 200, 800, 1000, 1900, 2500 comprising a first portion 110 and a second portion 120, a cutting accessory 130, and an electrical storage device 220 arranged in vibrational isolation from one another; First portion 110 includes 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 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.

[0149] Further disclosed are handheld power cutting tools 100, 200, 800, 1000, 1900, 2500 comprising a first portion 110 and a second portion 120, a cutting implement 130, and an electrical storage device 220 arranged in vibrational isolation from one another; First portion 110 includes 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 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 cutting disk (M1+M2+M3+M4) is at least 0.45, preferably greater than 0.5.

[0150] The following table provides exemplary weight distributions that may be advantageously used with the handheld power cutting tools discussed herein. Two different size battery examples are included in the table, with the larger battery weighing approximately 5100g (labeled M32) and the smaller battery weighing approximately 3000g (labeled M31).

[0151] [Table 1] [Explanation of symbols]

[0152] 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 Electrical storage device 240 Support Arm 245,250,251 Air outlet 260 Cutting Tool Interface 270 Holder 280 Ground support member 310 Opening 320 Cooling flange 330 Support surface 335 bolt holes 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 flow 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 Electrical storage devices, batteries 1820 Upper raised structure 1830 Lower raised structure 1840 Electrical Connector 1850 Handle 1910,1920 Damping member

Claims

1. A handheld power cutting tool (100, 200, 800, 1000, 1900) comprising a first part (110) and a second part (120) arranged in vibrational isolation from each other, the first part (110) comprises an arm (116) configured to support a cutting disc (130) and an electric motor (140) configured to drive the cutting disc; the second portion (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); one or more damping members (170, 1910) are disposed between the first portion (110) and the second portion (120), at least one damping member (170, 1910) being formed of a resilient material associated with a damping coefficient; The at least one damping member (170) comprises a bellows (2100) or other flexible air flow conduit (170) disposed between the first portion (110) and the second portion (120), the bellows (2100) or other flexible air flow conduit (170) directing air from the fan (145) toward the battery compartment (150).

2. 2. The handheld power cutting tool (100, 200, 800, 1000, 1900) of claim 1, wherein the at least one damping member (170, 1910) is configured to suppress or prevent vibration of the second portion (120) relative to the first portion (110).

3. 3. The handheld power cutting tool (100, 200, 800, 1000, 1900) of claim 1 or 2, wherein the at least one damping member (170, 1910) is made of rubber, a resilient plastic material, closed-cell foam, or a resilient synthetic resin.

4. A handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 3, wherein the first part (110) is vibrationally isolated from the second part (120) by one or more elastic members (210) in addition to the at least one damping member (170, 1910), the one or more elastic members (210) comprising at least one metal spring.

5. A handheld power cutting tool (100, 200, 800, 1000, 1900) as described in any one of claims 1 to 4, wherein a reinforcing element (1920) is arranged on at least one side of the bellows (2100) or other flexible air flow conduit (170), and the compressibility of the bellows (2100) can be adjusted by arranging one or more cavities (1930) in the reinforcing element (1920).

6. A handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 5, wherein a bellows (2100) or other flexible air flow conduit is arranged between the first part (110) and the second part (120), the bellows (2100) being associated with a Shore hardness value or Shore hardness measured with a durometer type A according to DIN ISO 7619-1 between 50 and 100, preferably between 65 and 90.

7. The handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 6, wherein the at least one damping member (1910) is fixedly attached to one of the first part (110) or the second part (120) and is positioned apart from the other of the first part (110) or the second part (120) but contacts the other of the first part (110) or the second part (120) upon vibration, and the at least one damping member (1910) is positioned to limit a stroke length of the oscillatory motion between the first part and the second part.

8. A handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 7, configured to operate at a cutting disc rotational speed of less than 3600 rpm, preferably about 3200 rpm.

9. The handheld power cutting tool (100, 200, 800, 1000, 1900) of any one of claims 1 to 8, wherein 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 disc (130) and detect a kickback condition based on a decrease in the angular velocity, and the control unit is configured to control an electromagnetic brake of the electric motor (140) in response to the detection of a kickback condition.

10. A handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 9, wherein the first portion is associated with a first mass (M1), the second portion is associated with a second mass (M2), and the ratio of the second mass (M2) to the sum of the first mass and the second mass (M1+M2) is at least 0.3, preferably greater than 0.

35.

11. the first portion is associated with a first mass (M1) and the cutting tool is associated with a fourth mass (M4); the second portion is associated with a second mass (M2) and the electrical storage device (220) is associated with a third mass (M3); A handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 10, wherein the ratio of the sum of the second mass and the third mass (M2+M3) to the sum of the first mass and the fourth mass (M1+M4) is at least 0.6, preferably greater than 0.8, and even more preferably greater than 1.

0.

12. the first portion is associated with a first mass (M1) and the cutting tool is associated with a fourth mass (M4); the second portion is associated with a second mass (M2) and the electrical storage device (220) is associated with a third mass (M3); A handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 11, wherein the ratio of the sum of the second mass and the third mass (M2+M3) to the sum of the weight of the entire device including the electrical storage device and the cutting disc is at least 0.45, preferably greater than 0.

5.

13. A hand-held power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 12, wherein a portion (160) of the cooling air flow from the first portion (110) to the second portion (120) is configured to pass through a control unit of the hand-held power tool (100).

14. A handheld power cutting tool (100, 200, 800, 1000, 1900) according to any one of claims 1 to 13, wherein a portion (160) of the cooling air flow directed from the first portion (110) to the second portion (120) passes through the bellows or other flexible air flow conduit (170).

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