Chainsaw, method for controlling a chainsaw, and computer program for carrying out such a method

Abstract

The handheld battery powered chain saw includes an electric motor (22) and a transmission arrangement (28) coupled to the electric motor (22), where the electric motor (22) is configured to drive a saw chain via the transmission arrangement (28). The transmission arrangement (28) includes a slip clutch (34) including a drive element (36) configured to receive rotational power from the electric motor (22) and a driven member (38) configured to transmit rotational power to the saw chain (16), where the slip clutch (34) is configured to at least partially disengage the electric motor (22) from the saw chain by allowing slip in the engagement between the drive element (36) and the driven member (38).

Description

[Technical Field]

[0001] The present invention relates to a handheld battery-powered chainsaw, a method for controlling such a chainsaw, as well as a computer program product for carrying out such a method and a data carrier for storing the computer program product. [Background technology]

[0002] Chainsaws have been around for about 100 years. While most chainsaws are still powered by two-stroke internal combustion engines due to weight-to-power and operating time considerations, battery-powered chainsaws are becoming increasingly popular. However, achieving high power, cutting efficiency, and usability without compromising other aspects of the chainsaw, such as weight and battery life, remains a challenge. Furthermore, there is a constant effort to make chainsaws safer and easier to use. Summary of the Invention [Problem to be solved by the invention]

[0003] It is an object of the present invention to solve or at least mitigate some or all of the above problems. [Means for solving the problem]

[0004] To this end, a handheld battery-powered chainsaw is provided, including an electric motor and a transmission arrangement coupled to the electric motor, wherein the electric motor is configured to drive a saw chain via the transmission arrangement, and the transmission arrangement includes a slip clutch including a drive element configured to receive rotational power from the electric motor and a driven member configured to transmit rotational power to the saw chain, the slip clutch being configured to at least partially disengage the electric motor from the saw chain by allowing slip in the engagement between the drive element and the driven member. The slip clutch may be a mechanical clutch, such as a centrifugal clutch, a belt clutch, a selectively engageable idler, an electromechanical / electromagnetic clutch, such as an electromagnetically actuated friction plate clutch, or a fluid coupling. As understood herein, a slip clutch is a clutch that allows or can be brought into a state that allows the drive member and driven member to slip relative to each other, thereby transmitting torque by slipping engagement, the transmitted torque being sufficient to drive the saw chain when the saw chain is unloaded. When activated, the clutch allows for gradual slipping engagement, gradually increasing power transmission without any reduction in the electric motor's rotational speed. This allows for easier (re)starting of the chain when already engaged with the material to be cut, since torque does not decrease in response to the rotational speed decreasing to zero. Additionally, increased inertia due to the electric motor's rotor can contribute to chain starting. Furthermore, the slip clutch provides soft engagement with the chain, which improves the general user experience. The slip clutch also provides feedback to the user when the saw chain is overloaded, for example, by the user pressing the saw chain too hard against the material to be cut, since with many clutch types it is fairly easy to hear when the clutch is slipping. Visual and / or tactile feedback instructs the user to release the load, and with high torque from the electric motor at low rotational speed, the electric motor directly restarts the chain, instantly restoring the chainsaw to high cutting efficiency.During slippage, the electric motor will not stall, even if the operator presses the saw chain too hard against the material being cut. Furthermore, some electric motor types only provide low-to-intermediate torque when stopped, while torque reaches its maximum at very low rotational speeds. The slip clutch thus allows for greater freedom in selecting an electric motor type. A handheld battery-powered chainsaw may further include a finger-operated trigger coupled to an electric switch for selectively operating the electric motor. The trigger may be configured to operate the electric motor at a stepped or continuous range of power, rotational speed, and / or output torque; alternatively, the trigger may be configured for simple on / off control of the electric motor. According to an embodiment, the drive element of the slip clutch may be rotatably fixed to the electric motor. Similarly, the driven member of the slip clutch may be rotatably fixed to a saw chain drive sprocket for driving the saw chain. According to further embodiments, the drive element may be rigidly connected to an output shaft of the electric motor, and / or the driven member may be rigidly connected to a saw chain drive element, such as a saw chain drive sprocket or keyed shaft configured to mate with a saw chain drive rim. According to embodiments, the chainsaw may include a battery compartment configured to receive a battery for powering the chainsaw. Alternatively or additionally, the chainsaw may be configured to be connected to, for example, an emergency battery. A typical suitable DC battery voltage range for powering the electric motor may be 18V to 100V, more preferably about 36V to about 72V. The electric motor may be configured to provide an output in an exemplary power range, for example, 1.8kW to 3.5kW.

[0005] According to embodiments, the transmission arrangement may be configured to provide a 1:1 transmission ratio between the electric motor and a saw chain sprocket meshing with the saw chain, where a 1:1 transmission ratio means that one full rotation of the electric motor corresponds to one full rotation of the saw chain sprocket when the drive element is rotationally locked to the driven element in a non-slip manner. According to embodiments, the saw chain sprocket may be coaxial with the output shaft of the electric motor.

[0006] According to embodiments, the slip clutch may be configured to transmit a slip torque of 2 Nm to 4.5 Nm while slipping. Such a torque range has been found to be well suited for handheld battery-powered chainsaws. According to some embodiments, the slip clutch may be configured to transmit a slip torque of 2 Nm to 3 Nm while slipping.

[0007] According to embodiments, the slip clutch may be movable between an engaged state, in which the slip clutch is configured to drive the saw chain, and a disengaged state, in which the drive element is free to rotate without driving the saw chain. This may allow for the use of a less expensive electric motor. For example, vector-controlled brushless DC motors often include a rotor position sensor to sense the exact rotor position within the motor, allowing the electric motor to start in the intended forward direction. The disengaged state may dispense with the rotor position sensor. A lack of information about the rotor position could lead to an electric motor inadvertently starting in reverse. After initial movement in reverse, the vector control automatically rotates the electric motor in the forward direction. In the disengaged state, such a direction reversal may go unnoticed by the operator because it can occur without moving the chain.

[0008] According to embodiments, the slip clutch can be configured to transition between engaged and disengaged states in response to changes in rotational speed. When using a handheld chainsaw, the chain does the work, but the operator typically applies a certain amount of force to obtain the best possible cutting efficiency. If too much force is applied, the chainsaw will eventually stall due to its torque limitations. With gasoline-powered chainsaws, there is an audible cue when the engine is being overloaded, allowing the operator to reduce the applied force to avoid stalling the engine. However, when an electric motor is overloaded, it typically stalls more suddenly and abruptly, often without any substantial audible, visible, or tactile cue. This can be frustrating for users, who need to release pressure on the chainsaw before being able to continue cutting. Stalling can also cause the saw chain to squeeze, for example, when felling a tree. As such, unplanned stalls can create potentially dangerous situations, as experienced chainsaw operators generally know. However, the use of a rotational speed-activated clutch in an electric chainsaw prevents sudden, unexpected stalling under heavy loads, for example, when cutting thick logs. Furthermore, the clutch's distinct engagement state or engagement speed makes it easier for the user to recognize an overload situation and back off before suddenly stalling the motor completely and affecting cutting efficiency too much. The relatively high torque characteristic of a typical electric motor at low to mid-range rpm makes it particularly well-suited for restarting the chain during, for example, felling trees. By way of example, the slip clutch may be an electromechanical clutch, and the chainsaw may include a controller configured to engage the electromechanical clutch based on the detected rpm of the electric motor. Alternatively, the slip clutch may be operated strictly mechanically, for example, by transmission inertia. According to an embodiment, the slip clutch may be configured to transition between disengaged and engaged states at a clutch engagement speed above which the clutch is engaged. The clutch engagement speed may be predetermined, for example, set as a control value in the chainsaw's controller or determined by the mechanical design of the centrifugal clutch.Exemplary suitable engagement speeds of the slip clutch may be between 2000 rpm and 7000 rpm, more preferably between 3000 rpm and 6000 rpm, and even more preferably between 4500 and 5800 rpm. The slip clutch may be actuated in response to changes in the rotational speed of the motor and / or drive element, for example.

[0009] According to embodiments, the slip clutch may be configured to transition between a slippable state, in which the drive element may slip relative to the driven member, and a lock-up state, in which the slip clutch is configured to drive the saw chain without slipping, in response to changes in the rotational speed of the drive element. According to embodiments, the slip clutch may be configured to transition from the slippable state to the lock-up state at a predetermined slip limit speed above which the slip clutch assumes a lock-up state. The slip clutch may be actuated to transition between the slippable state and the lock-up state in response to changes in the rotational speed of, for example, the motor and / or the drive element. The slip limit speed is defined as the rotational speed at which the clutch's slip torque, i.e., the torque required to slip the drive element relative to the driven member, exceeds the motor torque. Typically, for example, with a centrifugal clutch, the clutch's slip torque increases with the rotational speed of the drive element. Thereby, the slip limit speed is also the speed that would be imposed by the drive element if the driven member were held firmly in a non-rotating position while operating the chainsaw. Thus, the slip limit speed is higher than any of the engagement speeds as defined above. An exemplary suitable slip limit speed of the slip clutch may be 3500 rpm to 7500 rpm, more preferably 5500 to 7000 rpm. According to an embodiment, the slip torque at the slip limit speed is 2 Nm to 4.5 Nm. According to an embodiment, the slip torque at the slip limit speed is 2 Nm to 4.5 Nm. More preferably, the slip torque at the slip limit speed is 2 Nm to 3 Nm.

[0010] According to an embodiment, the slip clutch can be configured to transition between a disengaged state and an engaged state at a predetermined clutch engagement speed above which the clutch is engaged, and to transition from a slippable state to a locked-up state at a predetermined slip limit speed above which the slip clutch is locked-up, the slip limit speed being at least 200 rpm higher than the engagement speed. This naturally results in a smooth transition between the disengaged and locked-up states of the slip clutch. Sudden engagement of the slip clutch can suddenly decelerate the rotor of the electric motor, thereby inducing current peaks in the electric motor windings. This can cause overheating of the windings and / or voltage peaks or arcing, which can damage, for example, the drive electronics. By way of example, the stator windings of brushless DC motors are typically of the so-called air-gap winding type, which has limited ability to convect heat. According to a further embodiment, the slip limit speed is at least 1000 rpm higher than the engagement speed. Preferably, the slip limit speed is less than 2500 rpm higher than the engagement speed.

[0011] According to embodiments, the slip clutch may be inertia actuated, whereby the slip clutch may be actuated, i.e., transitioned between engaged and disengaged states and / or between slippable and lock-up states, by the inertia of a suitable portion of the transmission arrangement. For example, the slip clutch may be implemented as a centrifugal clutch. The slip clutch may also be actuated by a clutch actuation mechanism similar to a Bendix drive.

[0012] According to an embodiment, the slip clutch may be configured as a centrifugal clutch. The driven member may be configured as a clutch drum, and the driving element may include one or more friction shoes configured to move radially in response to rotation of the driving element, optionally against a resilient biasing member, into engagement with a radially inwardly facing surface of the clutch drum. The clutch drum may be rotatably mounted in a bearing on an output shaft of the electric motor.

[0013] According to an embodiment, the driven member may include a clutch drum having a diameter of 60 mm to 90 mm, and the driving element may include two or three, preferably two, friction shoes elastically connected to each other by elastic elements, where each friction shoe has an individual weight of 30 g to 70 g, and each elastic element 70 a, 70 b has a spring constant of 35 N / mm to 60 N / mm. It has been found that torque transmission at the slip limit speed of such a clutch is particularly well-matched to the behavior of electric motors in the preferred typical torque range of battery-powered chainsaws. A somewhat preferred range for the diameter of the clutch drum is 65 mm to 82 mm. Alternatively or additionally, a somewhat preferred range for the weight of each of the individual friction shoes is 40 g to 60 g. Alternatively or additionally, a somewhat preferred range for the spring constant of each of the elastic elements is 60 N / mm to 50 N / mm. According to a further embodiment, the product of the diameter of the clutch drum and the total weight of one set of friction shoes lies between 5000 g*mm and 10000 g*mm.

[0014] According to an embodiment, the slip clutch has a proximal side facing the electric motor and a distal side facing away from the electric motor, and the saw chain drive sprocket is connected to a driven member of the slip clutch on the distal side of the slip clutch. Such an arrangement facilitates access to the saw chain drive sprocket, which in turn facilitates, for example, replacing the saw chain. According to an embodiment, the driven member may be a clutch drum. The clutch drum is open toward the proximal side and can receive a drive element via the proximal side.

[0015] According to another embodiment, the slip clutch has a proximal side facing the electric motor and a distal side facing away from the electric motor, and the saw chain drive sprocket is connected to a driven member of the slip clutch on the proximal side of the slip clutch. Such an arrangement positions the chain drive sprocket near the lateral center of the chain saw, which is particularly suitable for compact chain saws. According to an embodiment, the driven member may be a clutch drum. The clutch drum is open toward the distal side and can receive a drive element through the distal side. Furthermore, the orientation of the clutch drum may be advantageously combined with a separate brake drum to brake the proximal side of the clutch drum and / or the driven side of the transmission arrangement on the proximal side of the saw chain drive sprocket.

[0016] According to an embodiment, the electric motor may include a rotor configured to be rotated by the stator, the rotor having a rotor outer diameter, and an output shaft drivingly connected to a drive element of a slip clutch, the output shaft having a shaft diameter, and a ratio of the rotor diameter to the shaft diameter between 2.5 and 4.8. This ratio range has been found to be suitable for achieving an appropriate balance between weight and durability of the transmission arrangement. The use of a slip clutch increases the length of the free end of the output shaft and the mass carried by the free end. The engagement surface of the driven member may have a clutch engagement surface diameter, and an exemplary suitable ratio of the rotor diameter to the clutch engagement surface diameter may be between 0.50 and 1.2. A typical suitable shaft diameter may be between 10 mm and 15 mm, for example. According to an embodiment, the clutch drum, as defined above, may be rotatably disposed on the output shaft via a bearing, e.g., a needle roller bearing. The shaft diameter may be the diameter of the shaft at the axial position of the bearing. Optionally, the output shaft may be provided with a lubrication passage extending from the needle bearing to a lubricant inlet in the end face of the output shaft.

[0017] According to embodiments, the slip clutch may be electromagnetically actuated based on a clutch control signal. For example, the slip clutch may be actuated by energizing a coil, thereby moving at least one of the drive element and the driven member axially, i.e., along the axis of rotation of the slip clutch, into engagement with the other of the drive element and the driven member. Optionally, the chainsaw may include a sensor configured to detect the engagement status of the slip clutch, i.e., whether the slip clutch is engaged or disengaged and / or whether the slip clutch is in a slippable or locked-up state. The status may then be communicated to the chainsaw operator. According to embodiments, the chainsaw may further include a controller configured to determine the rotational speed of the electric motor and control the engagement of the slip clutch based on the rotational speed. Such an arrangement may, for example, allow for greater freedom in selecting or adjusting the clutch engagement speed. According to some embodiments, the chainsaw is provided with a user interface that allows a user to set the clutch engagement speed.

[0018] According to embodiments, the handheld battery-powered chainsaw may further include a mechanical brake arrangement movable between a braking position, in which the mechanical brake arrangement is configured to engage the transmission arrangement to brake rotation of the driven member, and a release position, in which the driven member is allowed to rotate freely. According to embodiments, the mechanical brake arrangement is configured to engage the transmission arrangement on the driven member side of the slip clutch. This allows the mechanical brake arrangement to stop rotation of the saw chain regardless of the engagement position of the slip clutch. Alternatively or additionally, according to embodiments, the mechanical brake may include a brake drum and a brake band configured to be tightened around the brake drum. The brake drum may, in some cases, be separate from either clutch drum; alternatively, the brake band may be provided to engage a radially outer surface of the centrifugal clutch drum, thereby doubling as the brake drum.

[0019] According to embodiments, the handheld battery-powered chainsaw may further include a rear handle with a finger-operated trigger for operating the electric motor, and the mechanical brake arrangement may be configured to operate independently of the position of the trigger, thereby providing safe operation in all situations. According to embodiments, the mechanical brake arrangement may be configured to remain in a released position when the trigger is released, thereby allowing the inertia of the motor and transmission to be at least partially maintained when the trigger is released, thereby reducing power consumption. This may, of course, be particularly beneficial for battery-powered chainsaws.

[0020] According to embodiments, the driven member may include a clutch drum and the mechanical brake arrangement may include a brake band configured to apply a clamping force to a radially outer surface of said clutch drum in response to actuation of a brake actuator. The brake actuator may include a rebound brake lever configured as a hand guard on the front side of the chainsaw handle.

[0021] According to embodiments, the mechanical brake arrangement may include a brake drum axially separated from the slip clutch and a brake band configured to apply a clamping force to a radially outer surface of the brake drum in response to actuation of the brake actuator. According to further embodiments, the brake drum may be positioned proximal to the clutch, thereby resulting in a particularly compact arrangement. Again, the brake actuator may include a rebound brake lever configured as a hand guard on the front side of the chainsaw handle.

[0022] According to embodiments, the handheld battery-powered chainsaw may further include an electrically controlled brake, such as an electromagnetic brake and / or an induction brake. Such a brake may contribute to stopping the saw chain. The electrically controlled brake may be selectively activated by the controller, for example, in response to detecting that a trigger for operating the electric motor is released by the operator. For example, an induction brake may be implemented within the motor controller to selectively apply a braking force to the motor rotor. According to an alternative to the induction brake, the chainsaw may be configured to short-circuit the electric motor windings when the trigger is released by the operator.

[0023] According to embodiments, an electrically controlled brake may be configured to apply a braking force to the drive element side of the slip clutch, i.e., the motor, the drive element, and / or any elements fixedly attached thereto. Such an electrically controlled brake may provide a particularly compact and lightweight arrangement and may be beneficially combined with a mechanical brake to brake the driven element side of the slip clutch.

[0024] According to embodiments, the chainsaw may be configured to release the electrically controlled brake in response to the rotational speed of the electric motor falling below an electric brake release speed. The angular momentum of the motor and drive element may thereby be at least partially maintained when the trigger is released, which saves electrical energy and shortens the time it takes to accelerate the motor to the clutch engagement speed the next time the trigger is pressed. Furthermore, when combined with a fan, cooling of the motor and / or any battery and / or controls is improved. Preferably, when combined with a slip clutch that is activated in response to a change in rotational speed of the drive element as defined above, the electric brake release speed is greater than half the clutch engagement speed, and even more preferably at least 80% of the clutch engagement speed.

[0025] According to embodiments, an electric motor may include a rotor configured to rotate about a motor axis of rotation, and a drive element may be rotationally locked to the rotor in a snug, rotational fit to prevent rotation of the drive element in both directions of rotation about the motor axis of rotation. By way of example, the drive element may be secured to an output shaft of the electric motor by, for example, a keyway, a woodruff key, or a D-shaped keyed engagement. According to further embodiments, the drive element may be axially retained relative to the output shaft by, for example, a nut or screw, optionally in combination with a washer. The snug rotation lock may be particularly beneficial when combined with electric braking of the motor, because either braking or acceleration may cause the drive element to rotate relative to the rotor, even if there is a strong frictional engagement between them.

[0026] According to an embodiment, the handheld battery-powered chainsaw may further include a cooling fan that is always coupled to the drive element side of the slip clutch. This allows the cooling fan to be operated without the saw chain being operated. This allows any part of the chainsaw that can benefit from cooling, such as the motor, controller, and / or battery, to be cooled at any time. For example, the cooling fan may be operated to cool the chainsaw before use in high ambient temperatures or when the chainsaw has been stored in a warm environment. Furthermore, because chainsaws operate intermittently at maximum power in typical use cases, the cooling fan may cool the chainsaw during interruptions. This allows the chainsaw to be designed with higher peak power output without increasing the risk of overheating of any part thereof or, in some cases, without triggering any overheating protection mechanism. The cooling fan may be disposed within a housing shaped to direct airflow toward the motor, controller, and / or battery. According to a further embodiment, the cooling fan may be rigidly connected to the output shaft of the motor. The cooling fan may include a fan rotor with a set of blades configured to move cooling air. According to some embodiments, the cooling fan may be configured as an axial fan. According to other embodiments, the cooling fan may be configured as a centrifugal fan including an impeller arranged in a volute. The volute has the additional advantage of being well suited to achieving relatively high cooling air pressures, which are useful for forcing cooling air to all relevant areas when components are packed together in a compact configuration. The fan may be made of aluminum or plastic, for example.

[0027] According to an embodiment, the slip clutch may be positioned on a first axial side of the electric motor, and the cooling fan may be positioned on a second axial side of the motor opposite the first axial side. Such an arrangement allows the electric motor to be positioned toward the lateral center of the chainsaw, which ensures good balance of the chainsaw and increases comfort. According to an embodiment, the electric motor may be disposed within a motor housing, and the cooling fan may include a fan rotor with multiple blades, where the outer diameter of the cooling fan exceeds the diameter of the motor housing. This may enhance cooling of the slip clutch.

[0028] According to an embodiment, the handheld battery-powered chainsaw may further include a saw chain oil pump coupled to receive power from the driven member side of the slip clutch. This allows saw chain oil to be supplied to the saw chain only when the saw chain is moving, even when the electric motor is operating, thereby conserving saw chain oil. According to a further embodiment, the oil pump may be operated by the driven member side of the slip clutch via a worm drive. The worm screw of the worm drive may be coaxial with the rotational axis of the electric motor. According to an embodiment, the worm screw may be positioned between the electric motor and the slip clutch.

[0029] According to embodiments, the handheld battery-powered chainsaw may further include a controller configured to operate the slip clutch between an engaged state, in which the slip clutch is configured to drive the saw chain, and a disengaged state, in which the drive element is free to rotate without driving the saw chain. For example, the controller may operate the slip clutch in response to operator input by operating the electric motor at a rotational speed above or below the clutch engagement speed.

[0030] According to embodiments, the control device may be configured to maintain operation of the electric motor with the slip clutch disengaged. This allows any auxiliary components, such as a fan, connected to the motor or transmission arrangement on the drive side of the slip clutch to operate without operating the saw chain. In particular, the control device may be configured to maintain operation of the electric motor with the slip clutch disengaged in response to detecting that a finger-operated trigger for operating the electric motor has been fully released. For example, the slip clutch may be a centrifugal clutch, and the electric motor may be maintained at an idle speed below the engagement speed of the centrifugal clutch. The idle speed may be a predetermined speed set in the control device. Exemplary suitable idle speeds may be between 2000 rpm and 6000 rpm, more preferably between 3000 rpm and 5500 rpm. According to embodiments, the control device may be configured to maintain operation of the electric motor without engaging the slip clutch for a predetermined time, which is typically greater than 2 seconds, more typically greater than 10 seconds. Alternatively or additionally, the control device may be configured to maintain operation of the electric motor until an external event is detected, for example, the temperature of a predetermined part of the chainsaw drops below a threshold temperature or the power switch of the chainsaw is turned off. According to embodiments, the control device may be configured to automatically start operation of the electric motor without engaging the slip clutch when the chainsaw is switched on, for example by an on / off switch, or when it detects that the chainsaw has been lifted or the handle has been gripped.

[0031] According to an embodiment, the controller may be configured to maintain operation of the electric motor with the slip clutch disengaged, thereby operating a cooling fan of the chainsaw based on a condition in which the detected temperature exceeds a threshold temperature. According to a further embodiment, the chainsaw may further include at least one temperature sensor, and the detected temperature may be a temperature detected by the at least one temperature sensor. By way of example, the at least one temperature sensor may detect the temperature of the motor, the controller, and / or the battery. Alternatively, the detected temperature may be an ambient temperature detected by a temperature sensor external to the chainsaw. The threshold temperature may be fixed or dynamically set.

[0032] According to an embodiment, the handheld battery-powered chainsaw may further include a trigger movable between a depressed position in response to which the electric motor operates to move the saw chain and a released position in response to which the saw chain is stopped, wherein the control device is configured to enable operation of the electric motor when the trigger is in the released position.

[0033] According to embodiments, the controller may be configured to enable operation of the electric motor when the trigger is in the released position based on the condition that a mechanical brake configured to brake the driven member is engaged. Such an arrangement increases the safety of the chainsaw by mitigating the consequences of any failure of the slip clutch.

[0034] According to embodiments, the controller may be configured to detect excessive clutch slippage, for example, by detecting prolonged operation below a slip limit speed above which the slip clutch locks up; and, in response to detecting excessive clutch slippage, to make a change to a control signal for operating the electric motor. Excessive clutch slippage, i.e., clutch slippage for an excessively long period of time, is an undesirable condition that generates heat and contributes to wear on the slip clutch and electric motor. For example, the controller may be configured to determine that slippage has occurred for a time period that exceeds a predetermined slip limit time. Exemplary suitable changes to the control signal for operating the electric motor may automatically increase torque, which may, for example, increase the rotational speed of the slip clutch above the slip limit speed, thereby moving the saw chain, or automatically reduce the rotational speed of the motor toward or below the clutch engagement speed to reduce wear and heat generation. Additionally, changes in control of the electric motor may also contribute to an audible or tactile alert of excessive slippage to the chainsaw operator, who may take corrective action, for example, by reducing the pressure of the saw chain on the material to be cut or by releasing the trigger as defined above.

[0035] According to embodiments, making the change to the control signal for operating the electric motor may include pulsing the torque generated by the electric motor and / or varying the rotational speed of the electric motor. This effectively provides a fairly intuitive, audible, or tactile notification to the user that the electric motor is struggling to overcome the slip torque of the slip clutch, and the user may take corrective action, for example, by reducing the pressure of the saw chain on the material to be cut. Furthermore, pulsing torque or variable speed may facilitate re-starting a stuck saw chain. The torque may be pulsed, for example, by pulsing the drive current to the electric motor or by applying an intermittent phase shift to the drive current to the electric motor. According to some embodiments, the controller may be configured to pulse the torque at a pulse frequency greater than 20 Hz, preferably greater than 50 Hz, and provide an audible signal. According to other embodiments, the controller may be configured to pulse the torque at a pulse frequency between 0.2 Hz and 10 Hz, and even more preferably between 0.5 Hz and 5 Hz, and provide tactile feedback to the operator. The pulse frequency may be fixed or may vary within the pulse train. The pulses may be configured as square wave pulses, providing audible harmonics over a wide frequency range, thereby enabling the pulses to be heard even in complex background noise environments. Similarly, exemplary suitable speed variations may be periodic, e.g., at a frequency between 0.2 Hz and 10 Hz. Exemplary suitable amplitudes of rotational speed variations may be at least 10 rpm, more generally between 50 rpm and 1000 rpm.

[0036] According to embodiments, the control device may be configured to pulse the torque delivered by the electric motor for no more than a limited time or limited number of pulses, and then at a lower electric motor rotational speed below the clutch engagement speed. This allows the chainsaw to cool while further attempts to exceed the slip limit speed are prevented. This allows for higher electric motor power output without increasing the risk of overheating or damage to any components. The limited time or limited number of pulses may, in some cases, be predetermined. According to embodiments, the control device may be configured to pulse the torque for less than 30 seconds, more preferably less than 10 seconds, before reducing the electric motor rotational speed below the clutch engagement speed.

[0037] According to embodiments, a handheld battery-powered chainsaw may include a trigger movable between a depressed position in response to which the electric motor operates to move the saw chain and a released position in response to which the saw chain is stopped, wherein the controller is configured to reduce the rotational speed of the electric motor below the clutch engagement speed and then disable any desired speed increases up to the slip limit speed until the trigger is released and then pressed again. Such a configuration allows the operator to easily restart the chain using only the trigger.

[0038] According to an embodiment, the electric motor may be an outrunner, which includes a rotationally fixed stator with stator windings radially surrounded by a rotor with a set of permanent magnets. Outrunners generally cool themselves better than inrunners, reducing the need for a separate fan impeller. Furthermore, outrunners are generally less expensive than inrunners, but have higher rotational inertia, which causes them to accelerate more slowly. While high rotational inertia is a disadvantage when accelerating from start-up, it can be beneficial at higher rotational speeds when the saw chain engages the material to be cut. When combined with a clutch, the outrunner can be accelerated quickly when the clutch is disengaged, thereby providing the benefits of increased rotational inertia at higher speeds without the disadvantages of overly slow acceleration at lower speeds.

[0039] According to embodiments, the electric motor may be a vector-controlled permanent magnet motor, which offers good controllability that is well suited to the particular method of operation described herein. According to an embodiment, the control device may be configured to detect an electric motor overload and, in response, maintain or increase the torque of the electric motor. Motor overload may be detected by detecting that the rotational speed of the electric motor falls below a rotational speed expected for a given position of the trigger or for a given motor torque. Without a slip clutch, if a motor overload is detected, for example, by detecting that the rotational speed falls below a speed limit, it may be beneficial to quickly substantially reduce the electric motor torque, for example, by reducing the current supplied to the motor, to prevent the motor from overheating. However, when combined with a slip clutch, it may also be beneficial to maintain a high motor torque when an overload is detected, since the slip clutch will keep the motor completely stopped anyway. Maintained or increased torque in the rpm range of the slip limit speed facilitates restarting a saw chain that has become stuck, for example, due to lateral crushing or excessive pressure applied by the operator. Furthermore, when combined with a fan rotated by the motor, the fan maintains a flow of cooling air to the motor, thereby improving the prerequisites for maintaining a high torque.

[0040] According to an embodiment, a handheld battery-powered chainsaw may include a chainsaw body; an elongated guide bar for guiding a saw chain, the elongation direction of the guide bar defining an axis, the guide bar extending forward from a front end of the chainsaw body along the axis, the guide bar extending in a guide bar plane; a front handle; and a rear handle, the bottom surface of which includes a trigger to enable an operator to operate the electric motor, the rear handle having a plane parallel to the guide bar plane and including a rearmost point of the trigger intersecting the apex of the front handle at an intersection point, the distance between the intersection point and the rearmost point of the trigger being greater than 270 mm. Thanks to the slip clutch, a large distance can be provided between the front and rear handles without causing significant problems caused by the operator pressing the chain too hard against the material being cut, thereby improving the stability and controllability of the chainsaw. According to further embodiments, the distance between the intersection point and the rearmost point of the trigger may be greater than 300mm, 320mm, 340mm, or even 360mm.

[0041] According to embodiments, the chainsaw may be configured to operate the electric motor to maximum power, where the quotient of the distance from the intersection point to the rearmost point of the trigger versus the maximum power is greater than 0.11 mm / W. The clutch allows a relatively long distance between the rear and front handles to be combined with a moderately powered electric motor without risk of the electric motor stalling.

[0042] According to an embodiment, the chainsaw may be configured to operate the electric motor to generate a motor torque that reduces the slip torque at the slip limit speed as defined above, where the quotient of the slip torque versus the distance from the intersection point to the rearmost point of the trigger is greater than 90 mm / Nm. The clutch allows a relatively long distance between the rear handle and the front handle to be combined with the moderate torque of the electric motor without risk of stalling the electric motor.

[0043] According to a second aspect, some or all of the above problems are solved or at least alleviated by a handheld battery powered chainsaw including: an electric motor; a transmission arrangement coupled to the electric motor, the electric motor configured to drive the saw chain via the transmission arrangement; a controller for operating the electric motor; and a trigger operably coupled to the controller, the trigger movable between a depressed position in response to which the controller is configured to operate the electric motor to drive the saw chain, and a released position in response to which the controller is configured to stop driving the saw chain, the transmission arrangement including a clutch including a drive element configured to receive rotational power from the electric motor and a driven member configured to transfer rotational power to the saw chain, the clutch being movable between an engaged state in which the clutch engages the motor with the saw chain and a disengaged state in which the clutch disengages the motor from the saw chain allowing the drive element to rotate freely without driving the saw chain, and the controller configured to automatically maintain operation of the electric motor in an idle mode in which the clutch is disengaged when the trigger is in the released position. The idle mode maintains rotational inertia of the drive side of the motor and clutch, allowing for faster puffing of the saw chain once it is set in motion. The clutch, which may be a slip clutch or a dog clutch, for example, may be configured according to any of the embodiments defined below or above. According to embodiments, the clutch may be configured to transition between engaged and disengaged states based on the rotational speed of the electric motor, and the idle mode may be maintained by operating the electric motor at an idle speed below the clutch engagement speed. A chainsaw according to the second aspect may be combined with various embodiments of the chainsaw according to the first aspect as defined above.

[0044] According to embodiments, the clutch may be a centrifugal clutch, and the controller may be configured to automatically maintain operation of the electric motor in idle mode at an idle speed below the engagement speed of the centrifugal clutch. According to further embodiments, the controller may be configured to automatically maintain operation of the electric motor in idle mode at an idle speed more than 200 rpm below the engagement speed of the centrifugal clutch, and more preferably, at an idle speed more than 500 rpm below the engagement speed of the centrifugal clutch. Alternatively or additionally, the controller may be configured to automatically maintain operation of the electric motor in idle mode at an idle speed less than 3000 rpm below the engagement speed of the centrifugal clutch, and more preferably, at an idle speed less than 1500 rpm below the engagement speed of the centrifugal clutch. This is particularly useful in combination with a fan operated in idle mode.

[0045] According to an embodiment, the controller may be configured to automatically maintain operation of the electric motor in an idle mode at an idle speed between 2000 rpm and 6000 rpm, more preferably between 3000 rpm and 5500 rpm.

[0046] According to embodiments, the handheld battery-powered chainsaw may further include a cooling fan coupled for constant operation with the drive element side of the clutch. According to a third aspect, some or all of the above-mentioned problems are solved or at least alleviated by a handheld battery-powered chainsaw including: an electric motor; a transmission arrangement coupled to the electric motor, the electric motor configured to drive a saw chain via the transmission arrangement; and a flywheel configured to receive and store angular momentum from the electric motor, the flywheel being coupled to rotate about a flywheel axis of rotation together with at least a portion of the transmission arrangement. When using a chainsaw to cut logs, particularly for firewood, a user typically applies full throttle before beginning a cut. The added rotational inertia of the flywheel thereby results in a significant improvement. For example, the typical drop in chain speed upon contact with the wood is reduced, making it easier to make a complete cut. Furthermore, for arborists, for example, faster cutting of branches to be pruned is highly desirable because it reduces the tendency for the branches to droop before being completely cut. Results from conducted tests indicate that the added rotational inertia of the flywheel increases cutting speed when pruning. According to an embodiment, the flywheel may be carried by the output shaft of the drive motor and may optionally be rigidly connected thereto. According to an embodiment, the flywheel may have a weight of 80 g to 250 g. In general, it may have an outer diameter of 70 mm to 130 mm. An exemplary suitable range of the moment of inertia of the flywheel is 1.2*10 -4 kgm 2 ~3.5*10 -4 kgm 2Alternatively or additionally, at least 80%, more preferably at least 85%, of the flywheel's total weight may be radially positioned relative to the flywheel's rotation axis, over 50% of the flywheel's total radius. Such weight distribution results in a beneficial ratio of tare weight to rotational inertia. The chainsaw according to the third aspect may be combined with various embodiments of the chainsaw according to the first and second aspects as defined above. For example, the chainsaw may include a clutch as defined by any of the above embodiments. According to a further embodiment, the clutch may be positioned on a first axial side of the electric motor, and the flywheel may be positioned on a second axial side of the motor opposite the first axial side. The flywheel may optionally include blades to operate as a fan. A majority of the flywheel's weight may be provided by a metal, e.g., steel, inertia ring. The inertia ring may extend radially over at least 90% of the flywheel's total radius.

[0047] According to a fourth aspect, some or all of the above problems are solved or at least alleviated by a handheld battery-powered chainsaw including an electric motor including a rotor configured to be rotated about a motor axis of rotation; and a plurality of components configured to be rotated about the motor axis of rotation by the electric motor, wherein a sum of the moments of inertia of the rotor and the plurality of components is less than 1.5*10 -4 kgm 2 According to a further embodiment, the sum of the moments of inertia of the components is greater than 1.9*10 -4 kgm 2 and according to a further embodiment, the sum of the moments of inertia of the components may exceed 2.3*10 -4 kgm 2 It exceeds 2.8*10 -4 kgm 2 or even 3.5*10 -4 kgm 2The plurality of components may include all or a subset of the transmission arrangement components, the flywheel, and the fan as defined above.

[0048] According to a fifth aspect, some or all of the above problems are solved or at least alleviated by a handheld battery-powered chainsaw including an electric motor including a rotor configured to be rotated about a motor axis of rotation; and a plurality of components configured to be rotated by the electric motor about the motor axis of rotation, wherein the quotient J / M of the sum of the moments of inertia of the rotor and all components configured to be rotated by the electric motor about the motor axis of rotation, J, and the total mass M of the rotor and all components configured to be rotated by the electric motor about the motor axis of rotation, is 3.6 m 2 According to a further embodiment, the quotient is greater than 4.1 m 2 exceeded 4.6m 2 surpassed 5.1m 2 exceeded 5.6m 2 may exceed 6.1 m 2 Again, the sum of the moments of inertia of the rotor and all components configured to be rotated by the electric motor about the motor axis of rotation may be greater than 1.5*10, as defined above. -4 kgm 2 , 1.9*10 -4 kgm 2 , 2.3*10 -4 kgm 2 , 2.8*10 -4 kgm 2 , or 3.5*10 -4 kgm 2 It can exceed either of the above.

[0049] According to a sixth aspect, some or all of the above-mentioned problems are solved or at least alleviated by a method for controlling an electric motor for selectively driving a saw chain in a chainsaw including a trigger for initiating rotation of the saw chain, the method comprising: operating the electric motor before detecting trigger depression; and moving the saw chain in response to detecting trigger depression. Inertia of the motor and optional transmission arrangement thereby contributes to acceleration of the saw chain, which may result in a more rapid response of the chainsaw to trigger operation. Trigger depression may be detected relative to a fully released position. The method may be combined with any of the chainsaws defined above. According to one embodiment, the saw chain may be moved by engaging the electric motor with the saw chain via a clutch. Alternatively, the electric motor may be connected to the saw chain via a torque limiter, and the saw chain may be moved by releasing a mechanical chain brake. The method may further comprise: driving a cooling fan using the electric motor before detecting trigger depression.

[0050] According to embodiments, mechanically engaging the electric motor with the saw chain may include increasing the rotational speed of the electric motor above a clutch engagement speed. According to a seventh aspect, some or all of the above-mentioned problems are solved or at least alleviated by a method for controlling an electric motor for selectively driving a saw chain in a chainsaw including a trigger for initiating rotation of the saw chain, the method including: operating the saw chain in response to detecting depression of the trigger; stopping operation of the saw chain in response to detecting release of the trigger; and maintaining operation of the electric motor after stopping operation of the saw chain. This allows inertia to be stored / maintained until the next time the saw chain is operated, thereby saving energy. Alternatively or additionally, the electric motor may maintain operation of another function, such as operation of a fan. Operation of the motor may be maintained at least until just before the next trigger depression without again moving the saw chain. Stopping operation of the saw chain may include mechanically disengaging the electric motor from the saw chain. Alternatively, the electric motor may be connected to the saw chain via a torque limiter, and operation of the saw chain may be stopped by engaging a chain brake. The method may further include: driving a cooling fan using the electric motor after detecting the release of the trigger. Optionally, the method may comprise: operating the electric motor after detecting the complete release of the trigger. The method may be combined with any of the methods or chainsaws defined above.

[0051] According to embodiments, mechanically disengaging the electric motor from the saw chain may include reducing the rotational speed of the electric motor below a clutch engagement speed. According to an eighth aspect, some or all of the above-mentioned problems are solved or at least alleviated by a method for controlling an electric motor for selectively driving a saw chain in a chainsaw, the method comprising: operating the electric motor at a first rotational speed in response to detecting a trigger depression; and operating the electric motor at a second rotational speed in response to detecting a trigger release. The method may be combined with any of the methods or chainsaws defined above, for example, implemented in a chainsaw controller. Preferably, the saw chain may be coupled to be operated by the motor at the first rotational speed and decoupled from operation by the motor at the second rotational speed. According to embodiments, the chainsaw may include a fan coupled to be rotated by the electric motor when operated at the second rotational speed. Alternatively or additionally, the chainsaw may include a saw chain oil pump coupled to be operated by the electric motor at the first rotational speed and decoupled from operation by the motor at the second rotational speed. According to embodiments, the second rotational speed may be lower than a clutch engagement speed.

[0052] According to a ninth aspect, some or all of the above-mentioned problems are solved or at least alleviated by a method for controlling an electric motor for selectively driving a saw chain on a chainsaw including a clutch, the method including: determining a state of the clutch; and adjusting the torque or rotational speed of the electric motor and / or generating an alert to a chainsaw operator based on the determined clutch state. The method may be combined with any of the methods or chainsaws defined above. Exemplary clutch states may be a disengaged state, a slippable state, a slipped state indicating actual clutch slippage, and / or a lockup state. The method may include determining whether one of the exemplary conditions has occurred, is likely to occur, or is about to occur. For example, the method may include determining that the clutch has been slipping for a period exceeding a time limit, which may be predetermined or dynamically set. The alert or notice to the operator may be generated, for example, by turning on a light, sounding an alarm, or operating the electric motor in a predetermined pattern. According to an embodiment, determining the state may include determining the rotational speed of the electric motor. For rotational speed actuated clutches, the clutch state can result directly from the rotational speed.

[0053] According to an embodiment, determining the state of the clutch may include determining a current rotational speed. For example, torque or rotational speed may be adjusted in response to determining whether the chainsaw has been operated at a slip limit speed, as defined above, or at a slip-allowed speed between the clutch engagement speed and the slip limit speed for a time period exceeding a time limit. Alternatively, torque or rotational speed may be adjusted in immediate response to determining slip operation. Torque may be adjusted by controlling the current supplied to the motor.

[0054] According to an embodiment, the clutch state may be a slip state, and adjusting the torque or rotational speed of the electric motor may include reducing the rotational speed below the clutch engagement speed and / or reducing the torque of the electric motor. The torque or rotational speed reduction may be obtained by overriding any operator input, for example, from the trigger. This may avoid prolonged or excessively vigorous operation of the chainsaw at the clutch engagement speed, which reduces heat generation and extends the life of the clutch and any bearings.

[0055] According to embodiments, the clutch state can be a slip state, and adjusting the torque or rotational speed of the electric motor includes increasing the torque of the electric motor. The torque can be temporarily increased above the continuous operating torque without risking overheating the electric motor. This makes it easier to move a stalled chain, for example, if the saw chain is pressed too hard against the material to be cut or is crushed in the kerf. According to some embodiments, the speed and / or torque can be first reduced and then increased, or vice versa.

[0056] According to a tenth aspect, some or all of the above-mentioned problems are solved or at least alleviated by a method for controlling an electric motor for selectively driving a saw chain in a chainsaw, the method comprising: determining a current rotational speed; and activating an electromechanical clutch, e.g., an electromagnetic clutch, based on the determination. The electromechanical clutch can be engaged when the speed of the electric motor exceeds a clutch engagement speed. Similarly, the electromechanical clutch can be disengaged when the speed of the electric motor falls below a clutch disengagement speed. The engagement speed can be the same as the disengagement speed. Alternatively, they can be different. Again, the method can be combined with any of the methods or chainsaws defined above.

[0057] According to an embodiment, the method may further include receiving a clutch engage speed setting and / or a clutch disengage speed setting from a user interface, thereby allowing an operator or maintenance technician to set the desired engagement or disengagement speed to suit different applications. For example, in applications where there is a high risk of the saw chain jamming, a high clutch engage speed may be desirable, thereby benefiting from a high angular momentum of the motor to move the jammed chain.

[0058] According to an eleventh aspect, some or all of the above problems are solved or at least alleviated by a data processing device including at least one processor and a memory configured to perform any of the methods as defined above. The data processing device may be located in a handheld chainsaw, such as a handheld chainsaw as defined above. The data processing device may be embodied as a microcontroller.

[0059] According to a twelfth aspect, some or all of the above problems are solved or at least alleviated by a computer program product comprising instructions which, when the program is run on a processor, perform any of the methods as defined above.

[0060] According to a thirteenth aspect, some or all of the above mentioned problems are solved or at least alleviated by a computer readable storage medium having stored thereon a computer program product as defined above.

[0061] It should be noted that embodiments of the present invention may be embodied by all possible combinations of the features recited in the claims. Furthermore, it is understood that various embodiments described with respect to an apparatus may be combined with a method, and vice versa.

[0062] The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative, non-limiting detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, in which like reference numerals are used for like elements, and in which: [Brief explanation of the drawings]

[0063] [Figure 1A] 1 is a plan view of a handheld battery-powered chainsaw according to a first embodiment when viewed from the side; FIG. [Figure 1B] 1B is a plan view of the chainsaw of FIG. 1A when viewed from above. [Figure 2] FIG. 2 is a perspective view of the chainsaw of FIGS. 1A and 1B with the chain sprocket cover removed to expose the transmission arrangement. [Figure 3A] FIG. 3 is a perspective view of the electric motor of the chainsaw of FIG. 2 connected to the fan and transmission arrangement of FIG. 2; [Figure 3B] FIG. 3B is a plan view corresponding to the view of FIG. 3A. [Figure 4] 3B is an enlarged view of the interface area between the saw chain, the saw chain drive sprocket, and the guide bar of the chain saw of FIG. 1A, the view substantially corresponding to a cross section taken along line IV-IV of FIG. 3B. [Figure 5] 1B is a schematic block diagram showing the functional blocks of the electric motor and control device of the chainsaw of FIG. 1A; [Figure 6A] FIG. 3C is a perspective exploded view of the electric motor, fan, and transmission arrangement of FIGS. 3A and 3B. [Figure 6B] 4B is an exploded cross-sectional view of the electric motor, fan, and transmission arrangement of FIGS. 3A and 3B taken along line VI-VI of FIG. 4B. [Figure 7A] FIG. 6C is a first perspective view of the electric motor, fan, and transmission arrangement of FIGS. 6A and 6B. [Figure 7B] FIG. 7B is a second perspective view of the electric motor, fan, and transmission arrangement of FIG. 7A. [Figure 7C] 7B taken along axis A shown in FIG. 7A. FIG. 7B is a plan view of the electric motor, fan, and transmission arrangement of FIG. 7A. [Figure 7D] 7C is a cross-section of the electric motor, fan, and transmission arrangement of FIGS. 7A-C taken along line DD of FIG. 7C. [Figure 8A] 5 is a first diagram illustrating schematically the torque and rotational speed of the electric motor and transmission arrangement of FIG. 3A as a function of the rotational speed of the electric motor in a scenario when the saw chain of FIG. 4 is not obstructed. [Figure 8B] 5A and 5B are schematic diagrams illustrating the torque and rotational speed of the electric motor and transmission arrangement of FIG. 3A as a function of the rotational speed of the electric motor in the scenario in which the saw chain of FIG. 4 is jammed; [Figure 9] FIG. 10 is a perspective view of a chainsaw according to a second embodiment with the chain sprocket cover removed to expose the transmission arrangement according to the second embodiment. [Figure 10] 3B is a plan view of the electric motor of the chainsaw of FIG. 9 connected to the fan and transmission arrangement of FIG. 9, corresponding to the view of FIG. 3A. [Figure 11] FIG. 11 is a perspective view of the transmission arrangement of FIG. [Figure 12] FIG. 10 is a schematic cross-sectional view of an electric motor and transmission arrangement according to a third embodiment. [Figure 13] FIG. 10 is a schematic diagram of a transmission arrangement according to a fourth embodiment. [Figure 14] FIG. 10 is a schematic diagram of a transmission arrangement according to a fifth embodiment. [Figure 15] 10 is a flow chart illustrating a first method of operating the chainsaw of FIGS. 1A and 9. [Figure 16] 10 is a flow chart illustrating a second method of operating the chainsaw of FIGS. 1A and 9. [Figure 17]3B is a plan view corresponding to the view of FIG. 3A of the transmission arrangement according to the first embodiment, the fan, and the electric motor driving the flywheel according to the first embodiment; FIG. [Figure 18A] FIG. 3B is a plan view of the electric motor and transmission arrangement and combined fan and flywheel according to the first embodiment, corresponding to the view of FIG. 3A. [Figure 18B] 18B is a plan view of the combined fan and flywheel of FIG. 18A as viewed along axis A of FIG. 18A. [Figure 19] FIG. 2 is a perspective view of a data carrier. DETAILED DESCRIPTION OF THE INVENTION

[0064] All drawings are schematic, not necessarily to scale, and generally show only parts necessary to clarify the embodiments, and other parts may be omitted. FIG. 1A shows a handheld, battery-powered chainsaw 10. The chainsaw 10 includes a chainsaw body 12 with a pair of handles 14a, 14b by which an operator (not shown) can hold and operate the chainsaw 10. The pair of handles includes a front handle 14a for holding in a generally left hand and a rear handle 14b for holding in a generally right hand. A cutting assembly including a saw chain 16 and an elongated guide bar 18 that guides the saw chain 16 into an elongated loop extends from the front end of the chainsaw body 12 along an axis X of the chainsaw 10, which axis X is defined by the axis of the guide bar 18. A vertical axis Y of the chainsaw is perpendicular to the axis X and parallel to the plane of extension of the guide bar 18. The chainsaw 10 further includes a removable battery 20 within a battery compartment 20a, an electric motor 22 (shown only diagrammatically by a dashed circle in FIG. 1A ), and a finger-operated trigger 24 that enables an operator to selectively move the saw chain 16 using the electric motor 22. A rearmost point 24a of the trigger 24 along the direction of axis X is also shown in FIG. 1. The chainsaw further includes a controller 23 (shown only diagrammatically by a dashed box in FIG. 1A ) configured to control the electric motor 22 based on input from the trigger 24. The trigger 24 extends downwardly from the bottom surface of the rear handle 14b and is movable between a depressed position (not shown) in response to which the electric motor 22 is actuated to move the saw chain 16, and a released position (shown) in response to which the saw chain 16 is stopped. A handguard 25 in front of the front handle 14a is operably connected to a mechanical brake arrangement to stop the saw chain 16 in the event of recoil. The mechanical brake arrangement is a safety feature that operates regardless of the position of the trigger 24.

[0065] Figure 1B shows the chainsaw 10 as viewed from above. A plane P, parallel to the plane of the guide bar 18, includes the rearmost point 24a of the trigger 24. The plane P intersects with the vertex B of the front handle 14a with respect to the vertical direction Y of the chainsaw 10. Returning again to Figure 1A, the distance between the intersection point B and the rearmost point 24a of the trigger is approximately 300 mm.

[0066] FIG. 2 shows the chainsaw 10 without the saw chain 16 (FIG. 1A) and with the chain sprocket cover 26 (FIG. 1A) removed to expose the attachment of the guide bar 18 to the chainsaw body 12, along with a transmission arrangement 28 that transmits rotational power from the electric motor 22 (FIG. 1A) to the saw chain 16 (FIG. 1A).

[0067] 3A and 3B show the electric motor 22 and transmission arrangement 28 in greater detail. The transmission arrangement 28 includes, among other things, an output shaft 30 of the electric motor 22 configured to rotate about a motor rotation axis A, a saw chain sprocket 32 ​​( FIG. 3B ), and a slip clutch, in the illustrated embodiment of a centrifugal clutch 34. The centrifugal clutch 34 includes a drive element 36 that rotates with and receives rotational power from the electric motor 22 via the output shaft 30, and a driven element 38 that rotates with and transmits rotational power to the saw chain sprocket 32. As can be seen from FIG. 3B , the drive element 36, the driven element 38, and the saw chain sprocket 32 ​​are all configured to rotate concentrically about the motor rotation axis A. As can be seen from the configuration of the transmission arrangement 28, the transmission arrangement 28 provides a 1:1 transmission ratio between the electric motor 22 and the saw chain sprocket 32.

[0068] The transmission arrangement 28 further includes a brake drum 40 configured to cooperate with a brake band 40b operated by the hand guard 25, and a worm drive worm screw 42a for driving a saw chain oil pump (not shown). In the view of FIG. 3A, the brake band 40b is only shown very diagrammatically by dashed lines. Both the worm screw 42a and the brake drum 40a are rotatably fixed to the saw chain sprocket 32 ​​and rotate together with the driven member 38 of the centrifugal clutch 34. It will be apparent that both the worm screw 42a and the brake drum 40a are highly optional; saw chain oil may be pumped in by any other suitable means, if required, and the brake band 40b, if present, may instead conveniently cooperate with the radially outer surface of the driven member 38 of the centrifugal clutch 34.

[0069] 3B, the centrifugal clutch 34 has a proximal side 34a facing toward the electric motor 22 and a distal side 34b facing away from the electric motor 22, and the saw chain drive sprocket 32 ​​is rigidly connected to a driven member 38 of the centrifugal clutch 34 on the proximal side 34a of the centrifugal clutch. This arrangement positions the saw chain drive sprocket 32 ​​relatively close to the lateral center of the chainsaw 10 defined by plane P (FIG. 1B).

[0070] The transmission arrangement 28 is positioned on a first axial side 44a (FIG. 3B) of the electric motor 22 relative to the rotational axis A of the electric motor 22. A cooling fan 46 is rigidly connected to the output shaft 30 on a second axial side 44b (FIG. 3B) of the electric motor 22 opposite the first axial side 44a. The cooling fan 46 is thereby constantly coupled for operation with the electric motor 22 and the drive element side of the centrifugal clutch 34. The cooling fan 46 is configured as an axial fan and includes a fan rotor 48 with a set of blades 50 configured to blow cooling air over the electric motor 22 to cool it. The internal structure of the chainsaw body 12 (FIG. 1A) defines a fan housing (not shown), which is shaped to direct airflow over the electric motor 22, the controller 23, and / or the battery 20. The cooling fan 46 is preferably made of a lightweight material, such as plastic.

[0071] Figure 4 shows, in a cross section taken along line IV-IV in Figure 3B, a schematic representation of the saw chain sprocket 32, a short section of saw chain 16, and the proximal end of the guide bar 18. The saw chain sprocket 32 ​​is rotated by the motor 22 (Figure 1A) via a transmission arrangement 28 (Figures 3A and 3B) and is in driving engagement with the saw chain 16 to move it along the guide bar 18. As is known per se, the saw chain 16 includes a drive link 16a that meshes with drive teeth 32a of the saw chain sprocket 32, a cutter link 16b, and a tie strap 16c that joins the drive link 16a together.

[0072] FIG. 5 shows a schematic diagram of the functional elements of the electric motor 22 and the functional blocks of the controller 23 for controlling the electric motor 22. The electric motor 22 includes a stator 52 and a rotor 54 radially inwardly of and concentric with the stator 52. Alternatively, the electric motor may be of a different type, such as an outrunner (not shown). In the illustrated example, the electric motor 22 is a brushless DC (BLDC) motor or a permanent magnet synchronous motor (PMSM) with a permanent magnet rotor. The stator 52 may generally be a multi-phase stator, typically including three-phase windings 52a, 52b, and 52c. The windings 52a-c are controlled by an inverter 23a using a field-oriented control (FOC) scheme. The inverter 23a receives output from the battery 20 and supplies power to the motor windings 52a-c according to a pulse-width modulation scheme. A boost converter may be included in the inverter 23a to increase the voltage applied to the windings 52a-c. To use FOC, the individual currents applied to windings 52a-c may be measured, and the converter may convert these currents by Clarke / Park conversion unit 23b into DC and quadrature currents associated with currents parallel (DC) and perpendicular (quadrature) to the instantaneous magnetic field of rotor 54, respectively. These converted currents are provided to control logic 23c, which may also provide a sensor output from an optional angular position sensor 56 that estimates the orientation of rotor 54. Control logic 23c typically performs control operations, for example, based on a PI (proportional, integral) control scheme, to minimize the parallel current components that do not contribute to rotor torque and to obtain the desired perpendicular component that generates torque based on an input desired torque value obtained based on input from trigger 24 (FIG. 1A). In this manner, control logic 23c generates DC and quadrature voltages that are converted using inverse Clarke / Park and space vector modulation (SVM) modulation unit 23d to desired inverter duty cycle values ​​for inverter control to produce corresponding winding voltages, thereby enabling controller 23 to precisely control the output torque of electric motor 22, regardless of the rotational speed of electric motor 22.Controller 23 may be configured to enable electric motor 22 to provide a maximum torque Tm of, for example, 2 Nm to 4.5 Nm at output shaft 30 (FIG. 3A) at a rotational speed of approximately 4000 to 7000 rpm. Furthermore, controller 23 may be configured to enable electric motor 22 to provide an exemplary maximum power E of 1.8 kW to 4.5 kW at output shaft 30. Temperature sensor 57 communicates the temperature of electric motor 22 to controller 23, thereby enabling controller 23 to detect whether electric motor 22 is at risk of overheating. Controller 23 also includes a separate temperature sensor 23g, thereby enabling controller 23 to detect overheating of itself. Controller 23 also includes an induction brake 23e controlled by control logic 23c to selectively apply a braking force to the motor rotor, for example, when trigger 24 is released by the operator. The induction brake 23e can apply a braking force to the rotor 54, for example, by reversing the polarity of the magnetic field generated by the stator coils 52a-c or by short-circuiting the electric motor windings 52a-c. The control device 23 further includes a wireless connection interface 23f for communicating with an external user interface 27, for example a smartphone. Thereby, the control device 23 can receive settings and / or commands from an operator (not shown) via the external user interface and / or can send alerts to the operator via the external user interface 27. It will be apparent that the user interface may also be provided directly on the chainsaw body 12.

[0073] FIG. 6A is a perspective exploded view of the electric motor 22, fan 46, and transmission arrangement 28, while FIG. 6B shows the same items in cross section along the motor rotation axis A. The output shaft 30 has a first axial end 30a with a first end connection interface 31a for engaging with the drive element 36 of the centrifugal clutch 34. The first end connection interface 31a is configured as a keyed interface (not shown) for rotationally locking the output shaft 30 to the drive element 36; for example, the first end connection interface 31a may be configured as a D-shaped key. The drive element 36 may be axially held in place, for example, by a screw (not shown) that engages a threaded hole in the first axial end 30a of the output shaft 30. At its second axial end 30b opposite the first axial end 30a, the output shaft 30 has a second end connection interface 31b for engaging with the cooling fan 46. Again, the second end connection interface 31b is configured as a keyed interface for rotationally locking the output shaft 30 to the cooling fan 46. The cooling fan 46 may be held axially in place, for example, by screws (not shown) engaging threaded holes in the second axial end 30b of the output shaft 30. Adjacent to the second end connection interface 31b, the output shaft 30 has an intermediate connection interface 31c for engaging the rotor 54. Again, the intermediate connection interface 31c is configured as a keyed interface for rotationally locking the output shaft 30 to the rotor 54; in the illustrated example, the keyed interface is defined by a keyway. Between the intermediate connection interface 31c and the first end connection interface 31a, the output shaft 30 has a cylindrical section 31d that defines a bearing surface and is configured to radially support a bearing 58, for example, configured as a needle bearing. Although shown as a separate component for clarity, the saw chain sprocket 32 ​​may be welded to the driven member 38 of the clutch 34 .When assembled, the worm screw 42a, the clutch drum 40 and the saw chain sprocket 32 ​​are partially axially inserted into one another and fixed to one another in rotational interlock, as is apparent from their respective shapes shown in the diagram of Figure 6B. The worm screw 42a, the clutch drum 40, the saw chain sprocket 32 ​​and the driven member 38 of the centrifugal clutch 34 thereby define a rotationally rigid unit 60, which is radially supported on bearings 58 to allow rotation relative to the output shaft 30.

[0074] In the assembled state, the stator 52 is housed in a motor housing 62a, which is covered by a housing cover 62b, and the output shaft 30 rests on journals in bearings 64a, 64b, which are arranged in the motor housing 62a and the housing cover 62b, respectively. The view in Fig. 6A also clearly shows the permanent magnets 54a distributed around the periphery of the rotor 54, together with the windings 52a of the stator 52. As shown in Fig. 6B, the output shaft 30 is provided with lubrication passages 66 between the first axial end 30a and the cylindrical section 31d, which allow the bearing 58 to slide easily.

[0075] 7A-7D show transmission arrangement 28 in greater detail. The driven member 38 of centrifugal clutch 34 is configured as a clutch drum having a cylindrical inner clutch-engaging surface 38a. It will be appreciated that other shapes for the clutch-engaging surface 38a may be suitable for centrifugal clutches, such as a frusto-conical shape.

[0076] The drive element 36 includes a pair of friction shoes 68a, 68b bound by a pair of coil springs 70a, 70b. The friction shoes 68a, 68b are held in place axially by a friction shoe guide 72 for radially guided movement relative to the rotation axis A. The friction shoe guide 72 is rotationally fixedly attached to the output shaft 30. In response to rotation of the drive element 36, the friction shoes 68a, 68b are urged radially outward against the bias of the coil springs by centrifugal effects on the masses of the friction shoes 68a, 68b in a radial engagement direction toward the clutch engagement surface 38a of the clutch drum 38. This inertial actuation of the centrifugal clutch 34 occurs, and the inertia of the friction shoes 68a, 68b actuates the centrifugal clutch 34 in response to changes in rotational speed.

[0077] The diameter of the engagement surface 38a of the clutch drum 38 is approximately 70 mm. The weight of each of the friction shoes 68a, 68b is approximately 40 g, and the spring constant of each of the coil springs 70a, 70b is approximately 40 N / m. This allows the centrifugal clutch 34 to transmit torque at a slip limit speed of approximately 2 Nm.

[0078] While the example shows two friction shoes 68a, 68b and two coil springs 70a, 70b, it will be apparent that other numbers of friction shoes and springs may be used. Furthermore, elastic elements other than coil springs may also be used to bias the friction shoes 68a, 68b radially inward. In fact, for purposes of this disclosure, the coil springs 70a, 70b or any other elastic elements biasing the friction shoes 78a, 78b radially inward may be optional, as the coil springs 70a, 70b are not required to enable the clutch to move between a locked-up state and a slippable engaged state. The centrifugal clutch 34 operates as a slip clutch, i.e., it allows slippage between the drive element 36 and the driven member 38 in some cases. Thanks to this slippage capability, the electric motor 22 may continue its operation even if the saw chain 16 (FIG. 1A) becomes stuck. This provides several benefits, as will be apparent herein.

[0079] Referring now to FIG. 7C, the rotor 52 (schematically represented by a dashed circle) has a rotor outer diameter D1, and the output shaft 30, at the axial location of the bearing 58, has a shaft diameter D2. When combined with the slip clutch 34, an exemplary preferred ratio D1 / D2 of the rotor diameter D1 to the shaft diameter D2 is between 2.5 and 4.8; in the illustrated example, it is approximately 4. The engagement surface 38a of the clutch drum 38 has a clutch-engagement surface diameter D3, and an exemplary preferred ratio D1 / D3 of the rotor diameter D1 to the clutch-engagement surface diameter D3 is between 0.50 and 1.2; in the illustrated example, it is approximately 0.75. The illustrated output shaft 30, at the axial location of the bearing 58, has a diameter D2 of approximately 12 mm. As can be seen, for example, from FIG. 3B, the cooling fan 46 has an outer diameter greater than the diameter of the motor housing 62a, which improves the flow of cooling air to the centrifugal clutch 34.

[0080] The cross section of Figure 7D shows, among other things, the worm drive 42 and the meshing engagement between the worm screw 42a and the worm wheel 42b driven by the worm screw 42a. The schematic diagrams of FIGS. 8A and 8B show the rotational speed ω of the electric motor 22 (FIG. 3A). m 3A shows an exemplary general behavior of the centrifugal clutch 34 (FIG. 3A) as a function of the rotational speed ω of the drive element 36. C1 is the rotational speed ω of the electric motor 22 m while the rotational speed ω of the driven member 38 C2 depends on the state of the clutch 34 (FIG. 3A) and the load on the saw chain 16 (FIG. 1A). When the electric motor 22 starts, at low rotational speeds, the centrifugal clutch 34 is in a disengaged state, i.e., runs freely with the friction shoes 68a, 68b not engaged with the clutch drum 38. The engagement speed ω E When the speed ω reaches the clutch engagement surface 38a (FIG. 7A), the friction shoes 68a, 68b (FIG. 7A) engage the clutch engagement surface 38a (FIG. 7A) of the clutch drum 38 and begin to slip relative thereto. C1 As the slip torque T of the centrifugal clutch 34 increases, s, i.e., the torque required to slip the driving element 36 relative to the driven member 38, also increases.

[0081] Here, two different scenarios can be considered: In both scenarios, the electric motor operates at its maximum torque T suitable for long-term operation. m In the first scenario shown in Figure 8A, the saw chain 16 (Figure 1A) runs freely along the guide bar 18 (Figure 1A) and the speed of the driven member 38 is ω C2 immediately the speed ω of the driving element 36 C1 , i.e., end the slip.

[0082] In a second scenario, shown in Figure 8B, the saw chain 16 (Figure 1A) may, for example, be pinched in the kerf or otherwise prevented from traveling along the guide bar 18 (Figure 1A). In this scenario, the velocity ω of the driven member 38 C2 is the torque required to move the saw chain 16, which is the torque T of the electric motor 22. m The rotational speed ω of the driving element 36 remains zero as long as C1 , and the rotational speed ω of the electric motor 22 m is the slip torque T of the centrifugal clutch 34. s is the motor torque T m The slip limit speed ω is equal to L It can't be faster than that.

[0083] Therefore, proceeding from the first no-load scenario to the second loaded scenario, consider: L Super rotation speed ω m and the load to which the saw chain 16 is exposed gradually increases (this load is determined by the motor torque T m , the drive and driven members 36, 38 remain locked to one another and their individual rotational speeds ω C1 , ω C2 are the slip limit speeds ω LAt that speed, the driven member 38 comes to a sudden complete stop while the driving element 36 continues to travel down to the slip limit speed ω L Remain.

[0084] Engagement speed ω E and slip limit speed ω L Exemplary values ​​for ω are, for example, E = approximately 5000 rpm and ω L = approximately 6500 rpm. For completeness, due to friction hysteresis of clutch slip, the slip limit speed ω L is the slip limit value at a higher or lower rotational speed ω of the driven member 36. C1 For simplicity, this effect is ignored here.

[0085] 0~ω E In the rotational speed range of electric motor 22, the centrifugal clutch is in a disengaged state and electric motor 22 operates without moving saw chain 16. The disengaged state allows electric motor 22 to be used without moving saw chain 16 for various purposes. For example, electric motor 22 can be set to an engaged speed ω either by an operator via trigger 24 (FIG. 1A) or automatically by control device 23 (FIG. 1A). E to allow the engine to cool down after performing laborious cuts.

[0086] ω E ~ω L In this rotational speed range of the electric motor 22, the centrifugal clutch is in a slippable state, where excessive load causes or increases slippage of the centrifugal clutch 34. In other words, when in a slippable state, the centrifugal clutch 34 may also be considered to be in a slipping state, i.e., begin to slip. The slippable state also enables new features and functions of the electric motor 22. For example, if the operator presses the saw chain 16 too hard against the material to be cut, the slippage may generate an audible cue, which may alert the operator to the slippage so the operator can reduce pressure.

[0087] ω L In the range of rotational speed of the electric motor 22 above ω , the centrifugal clutch 34 is in lockup, where the overload does not slip and the electric motor 22 speed ω m This may result in a decrease in

[0088] The state of the centrifugal clutch allows for various control methods that can be implemented in the control logic 23c of the controller 23. The control logic 23c, which can be implemented in a microcontroller, includes a processor and memory for executing the various control methods. The controller 23 can also be configured to automatically detect slip conditions, i.e., actual or at least suspected slip of the clutch 34. This can be done, for example, by detecting a slip limit speed ω for a period exceeding a time limit. L By detecting the operation at the set speed ω s When the electric motor 22 tries to reach the slip limit speed ω L or by detecting that the motor speed ω m and ω at the driven member 38 C2 The rotational speed ω of the driven member 38 as received from a separate rotation sensor (not shown) that detects C2 For example, the control device 23 (FIG. 5) may compare the rotational speed ω of the electric motor 22. m is the speed limit, e.g., the engagement speed ω E or the electric brake release speed ω defined separately R , the inductive brake 23e (FIG. 5) may be configured to release when the

[0089] Figure 9 shows a handheld battery-powered chainsaw 110 according to a second embodiment. The chainsaw 110 is again shown with its chain sprocket cover 26 (Figure 1A) removed and is identical to the chainsaw 10 of the first embodiment (Figure 1A) except that the chainsaw 110 of Figure 9 includes a transmission arrangement 128 according to the second embodiment, replacing the transmission arrangement 28 described with reference to the chainsaw 10 of the first embodiment. The transmission arrangement 128 of Figure 9 also includes a slip-type centrifugal clutch 34.

[0090] FIG. 10 shows the electric motor 22 and transmission arrangement 128 of FIG. 9 in greater detail in a view corresponding to FIG. 3B, while the exploded view of FIG. 11 shows the transmission arrangement 128 of FIG. 10 in even greater detail. The transmission arrangement 128 of FIG. 10 does not include a separate brake drum 40 (FIG. 3A). Instead, the clutch drum 38 also operates as the brake drum 40a, and a brake band (not shown), operated by the hand guard 25 (FIG. 9), engages the outer mantle surface of the clutch drum 38. Unlike the embodiment shown in, for example, FIG. 3B, the saw chain drive sprocket 32 ​​is rigidly connected to the clutch drum 38 at the distal side 34b of the centrifugal clutch 34. The clutch drum 38 instead opens toward the proximal side 34a of the clutch 34 to receive the drive element 36 from the proximal side 34a. As in the first embodiment 28, the drive element 36 includes a pair of friction shoes 68a, 68b and a friction shoe guide 72 driven by the output shaft 30 of the motor 22, for example, via a keyway 31a. In the view of FIG. 10, the position of the drive element 36 is indicated schematically by a dashed line. The clutch drum 38 and worm screw 42a for driving the saw chain oil pump are rotatably mounted on a journal of the output shaft 30, allowing them to rotate independently of the drive element 36. A metal wire spring 43a (FIG. 10) attached to the worm screw 42a engages with a notch 43b (FIG. 11) in the clutch drum 38, causing the worm screw 42a to rotate together with the clutch drum 38. The saw chain drive sprocket 32 ​​and clutch drum 38 are axially held relative to the output shaft 30 of the motor 22 by a screw head 33 (FIG. 10), thereby engaging the output shaft 30.

[0091] FIG. 12 schematically illustrates the electric motor 22 and a transmission arrangement 228 according to a third embodiment. The transmission arrangement 228 replaces the transmission arrangements 28 and 128 described above in the chainsaw 10 (FIG. 1A). The transmission arrangement 228 according to the third embodiment includes an electromagnetic clutch 234, the rotation axis of which is concentric with the rotation axis A of the electric motor 22. The electromagnetic clutch 234 includes a driving element configured as a clutch rotor plate 236, a driven element configured as an armature plate 238, and a field coil 241 controlled by the control logic 23c (FIG. 5) of the controller 23 (FIG. 1A). The controller 23 is configured to selectively activate the clutch 234 by generating a current in the field coil 241, thereby magnetizing the clutch rotor plate 236. The magnetic field generated by the field coil 241 attracts the armature plate 238 along the motor rotation axis A, thereby bringing the armature 238 into contact with the rotor plate 236. Depending on the current generated in the field coil 241, the clutch 234 may be in a disengaged state, in which the clutch rotor plate 236 is allowed to rotate freely without moving the saw chain 16 (FIG. 1A), or in an engaged state, in which torque is transmitted to move the saw chain 16. When in the engaged state, the clutch 234 may be in a slippable state, in which the clutch rotor plate 236 may slip relative to the armature plate 238, or in a locked-up state, in which the clutch 234 is configured to drive the saw chain 16 without slipping. The controller 23 may thereby selectively set the clutch to either of the above-mentioned states. It will be apparent that the controller 23's control signal to the field coil 241 provides the controller 23 with a priori knowledge of whether the clutch 234 is engaged or disengaged. Alternatively, the clutch state sensor 74 may directly detect the state of the clutch 234, for example, by detecting the axial position of the armature plate 238, thereby allowing the controller to detect whether the clutch is engaged or disengaged. The rotation sensor 76 detects the rotational speed ω of the armature plate 238. C2 The rotation speed ω of the armature plate 238 is detected. C2and the rotational speed ω of the electric motor 22 m By comparing the rotational speed ω of the electric motor 22 (FIG. 1A), the controller 23 can determine whether the clutch is in a slipping state; thereby, the rotational speed sensor 76 acts as a slip detector. According to some embodiments, the controller may adjust the clutch 234 relative to the rotational speed ω of the electric motor 22 (FIG. 1A). m 12 can be configured to operate in a manner similar to, for example, the centrifugal clutch 34 of FIG. 6A. The engagement speed ω for transitioning between clutch states can be E and slip limit speed ω L can optionally be set by the operator via the user interface 27. In fact, the velocity ω m For example, the controller may set a different speed limit depending on whether the engagement speed ω E At this time, the clutch 234 is transitioned from a disengaged state to an engaged state, and the engagement speed ω E The disengagement speed ω may be different from D The controller 23 (FIG. 5) may be further configured to release the induction brake 23e (FIG. 5) whenever the electromagnetic clutch 234 is in the disengaged state.

[0092] FIG. 13 schematically illustrates a transmission arrangement 328 according to a fourth embodiment. The transmission arrangement 328 may replace the transmission arrangements 28, 128, and 228 described above in the chainsaw 10 (FIG. 1A). The transmission arrangement 328 according to the fourth embodiment includes an electromechanical clutch configured as a belt clutch 334. The belt clutch 334 includes a drive element configured as a drive pulley 336 attached to the drive shaft 30 and receiving rotational power from the electric motor 22 (FIG. 1A), and a driven member configured as a driven pulley 338 attached to the saw chain drive sprocket 32. In the illustrated embodiment, the drive element 336 and the driven member 338 may rotate about parallel, but non-concentric, axes of rotation. The drive pulley 336 and the driven pulley 338 are connected by a drive belt 337, the tension of which may be controlled by adjusting the position of an idler wheel 339. Depending on the tension in the drive belt 337, the clutch 334 may be in a disengaged state, in which the drive pulley 336 is allowed to rotate freely without moving the saw chain 16 (FIG. 1A), or in an engaged state, in which torque is transmitted to move the saw chain 16. When engaged, the clutch 334 may be in a slippable state, in which the drive pulley 336 may slip relative to the driven pulley 338, or in a locked-up state, in which the clutch 334 is configured to drive the saw chain 16 (FIG. 1A) without slipping. The idler wheel 339 is moved by a clutch actuator 341 in response to a control signal generated by control logic 23c of the controller 23 (FIG. 1A). The controller may thereby selectively set the clutch to either of the above-described states.

[0093] 14 schematically illustrates yet another transmission arrangement 428 according to a fifth embodiment, which may replace the transmission arrangements 28, 128, 228, 328 described above. The transmission arrangement 428 according to the fifth embodiment includes a drive wheel 436 attached to the drive shaft 30 and a driven wheel 438 attached to the saw chain drive sprocket 32. An electromechanical clutch 434 is configured as a selectively engageable idler wheel 439 between the drive wheel 436 and the driven wheel 438. Again, the idler wheel 439 is moved by a clutch actuator 341 in response to a control signal generated by the control logic 23c of the controller 23 (FIG. 1A), thereby enabling the controller 23 to set the clutch 434 to any of the conditions described above.

[0094] FIG. 15 illustrates a first method of controlling the electric motor 22 to selectively drive the saw chain 16. In a first method step 1001, the control device determines the state of the clutch 34, 234, 334, 434. The state of the clutch can be determined, for example, by determining the rotational speed of the electric motor 22 in the case of a rotational speed-activated clutch, by determining the clutch setting in the case of an electromagnetic or electromechanical clutch, or by detecting the actual slip condition as described above.

[0095] In a second method step 1002, the control device 23 determines the torque T of the electric motor based on the determined clutch state. m and / or rotation speed ω m and / or generate an alert to the chainsaw operator.

[0096] According to one embodiment, step 1001 may include, for example, determining that the clutch 34, 234, 334, 434 is in a slipping state or has been in a slipping state for a period exceeding a time limit. Step 1002 may include, for example, by lighting a light, activating an alarm, or by, for example, reducing the rotational speed ω of the electric motor 22. m and / or torque T mThis may include generating an alert to an operator, for example, by operating the electric motor 22 according to a predetermined pattern by varying the rotational speed ω of the electric motor 22. m and / or torque T m can be pulsed with a pulse frequency that is, for example, audible or tactilely perceptible. In the case of a centrifugal clutch 34, the slip limit speed ω m Torque T nearby m Pulsing the can help restart a stuck saw chain.

[0097] According to another embodiment, step 1001 may again include, for example, determining that the clutch 34, 234, 334, 434 is in a slipping state or has been in a slipping state for a period exceeding a time limit. Step 1002 may include, for example, determining the torque T of the electric motor 22. m is the maximum torque T allowed for continuous operation of the electric motor. max Excess torque T + This may include temporarily increasing the torque T + However, it may be possible to move the stuck saw chain 16 (Figure 1A).

[0098] According to yet another embodiment, step 1001 may again include, for example, determining that the clutch 34, 234, 334, 434 is in a slipping state or has been in a slipping state for a period of time that exceeds a time limit. m and / or rotation speed ω m In the case of a rotational speed actuated clutch, such as a centrifugal clutch 34 (FIG. 3A), for example, the controller 23 may ignore any input from the trigger 24 (FIG. 1A) and reduce the rotational speed ω m The engagement speed ω of the clutch 34 E The controller may automatically reduce the rotational speed ω to less than ω 1 until the operator first releases the trigger 24 and then presses it again. m The engagement speed ω EIt may be configured to refrain from allowing it to go any higher than this.

[0099] According to yet another embodiment, step 1001 may again include, for example, determining that the clutch 34, 234, 334, 434 is in a slipping state or has been in a slipping state for a period of time that exceeds a time limit. Step 1002 may include first determining the rotational speed ω of the electric motor 22 during the limited time if the trigger remains fully depressed. m and / or torque T m , thereafter ignoring any input from the trigger 24, and, for example, in the case of the centrifugal clutch 34 (FIG. 3A), varying the rotational speed ω m The engagement speed ω of the electric motor 22 E This may include automatically disengaging the clutch 34, 234, 334, 434 by lowering the clutch 34, 234, 334, 434 below the preset value.

[0100] According to yet another embodiment, step 1001 may include, for example, determining that clutch 34, 234, 334, 434 is disengaged. Step 1002 may include operating electric motor 22 at a predetermined rotational speed suitable for operating cooling fan 46 and / or reducing motor torque T by reducing current to rotor windings 52a-c. m This may include lowering the fan temperature to result in lower power consumption while still allowing the fan 46 to operate.

[0101] FIG. 16 illustrates a second method of controlling the electric motor 22 to selectively drive the saw chain 16. In step 2001, the controller detects that the trigger 24 (FIG. 1A) is in a fully released position and then activates the electric motor 22, thereby operating the fan 46 (FIG. 3A).

[0102] In step 2002, depression of trigger 24 is detected by controller 23 (FIG. 5), and in response controller 23 engages clutches 34, 234, 334, 434, thereby moving saw chain 16 (FIG. 1A) and operating the saw chain oil pump.

[0103] In step 2003, the complete release of the trigger 24 is detected by the controller 23, and in response the controller disengages the clutch 34, 234, 334, 434, thereby immobilizing the saw chain 16.

[0104] In step 2004, the controller maintains operation of the electric motor 22 after full release of the trigger 24, disengagement of the clutch 34, 234, 334, 434, thereby maintaining operation of the fan 46.

[0105] According to one embodiment, in step 2001 and / or step 2004, controller 23 may be configured to operate electric motor 22 based on the further condition that a temperature reading from a temperature sensor, e.g., motor temperature sensor 57 or controller temperature sensor 23g, exceeds a threshold temperature. Controller 23 may also, or instead, be configured to maintain operation of electric motor 22 for a predetermined period of time, e.g., 30 seconds, to allow the electric motor to cool after being disconnected. Alternatively or additionally, controller 23 may be configured to operate electric motor 22 based on the further condition that the mechanical brake arrangements 40a, 40b (FIG. 3A) are engaged, e.g., that the mechanical brake arrangements 40a, 40b are engaged.

[0106] In the case of a rotational speed actuated clutch, such as the centrifugal clutch 34 (FIG. 3A), in step 2002 the controller calculates the rotational speed ω m The engagement speed ω of the centrifugal clutch 34 E In steps 2001 and / or 2004, the controller 23 may adjust the idle speed ω to, for example, about 4000 rpm. i(FIG. 8A) can be configured to operate the electric motor 22.

[0107] In optional step 2000 preceding step 2001, the control device 23 may automatically start operation of the electric motor 22 without engaging the slip clutch in response to the chainsaw 10 being switched on, for example via an on / off switch (not shown), and / or in response to detecting that the chainsaw 10 has been lifted, for example as indicated by an accelerometer (not shown), and / or in response to detecting that one or both handles 14a, 14b have been gripped by the operator, for example as indicated by a capacitance sensor (not shown) on the handles 14a, 14b.

[0108] FIG. 17 schematically illustrates yet another transmission arrangement 528 according to a sixth embodiment, which may replace the transmission arrangements 28, 128, 228, 328, and 428 described above in the handheld battery-powered chainsaw 10 or 110 of FIG. 1A. The transmission arrangement 528 according to the sixth embodiment differs from the transmission arrangement 128 of FIG. 11 in that it does not include a clutch. Instead, the brake drum 40a, worm screw 42a, and saw chain drive sprocket 32 ​​are coupled to rotate constantly with the electric motor 22. The saw chain drive sprocket 32, brake drum 40a, and worm screw 42a all engage keyways in the output shaft 30 (FIG. 11) and are held axially in place by screws 33 and washers. Additionally, in the illustrated embodiment, the electric motor 22 also drives the flywheel 90. The flywheel 90 is coupled to rotate with the rotor 54 (FIG. 6A) of the electric motor 22 about a flywheel axis of rotation that coincides with the rotation axis A of the electric motor 22. The flywheel 90 thereby receives and stores angular momentum from the electric motor 22, which contributes to maintaining the speed of the saw chain 16 (FIG. 1) as it engages the material to be cut. The flywheel 90 is attached to the output shaft 30 on the distal side 44c of the fan 46, i.e., on the side of the fan 46 that faces away from the electric motor 22. An axial gap is provided between the flywheel 90 and the fan 46, which reduces any tendency of the flywheel 90 to obstruct airflow into the fan 46. According to an alternative embodiment (not shown), the flywheel 90 is provided on the proximal side of the fan 46, i.e., on the side of the fan 46 that faces the electric motor 22. Such a configuration moves the mass and moment of inertia of the flywheel 90 closer to the lateral center of the chainsaw 10 (FIG. 1), thereby improving the agility of the chainsaw 10, i.e., making it easier for an operator to move the chainsaw 10 while working. The flywheel 90 weighs approximately 125 g and has an outer diameter of approximately 90 mm.In particular, the flywheel 90 is configured as a steel inertia ring suspended from the output shaft 30 via spokes (not shown) so that the weight of the flywheel 90 is concentrated at the radially outermost portion of the flywheel 90 relative to the axis of rotation A. The spokes also allow axial airflow into the fan 46. In the embodiment of FIG. 17, the sum of the moments of inertia J of the rotor 54 (FIG. 6A) and all components rotated by the rotor 54 (i.e., including the shaft 30, fan 46, brake drum 40a, worm screw 42a, saw chain drive sprocket 32, and flywheel 90) is approximately 2.4*10. -4 kgm 2 The flywheel 90 corresponds to about 60% of the total moment of inertia, or about 1.4*10 -4 kgm 2 The total mass M of the rotor 54 and all components rotated by the rotor 54 is approximately 440 g, so that the quotient J / M of the mass M and the moment of inertia J is approximately 5.5 m. 2 A large quotient of J / M indicates a high weight efficiency of the inertial energy storage of the chainsaw 10.

[0109] FIGS. 18A and 18B show a flywheel 190 according to a second embodiment, in which the flywheel 190 is connected to the transmission arrangement 28 of the first embodiment, as shown in FIGS. 3A and 3B, including the clutch 34. FIG. 18B shows the flywheel 190 as viewed along the axis of rotation A of the electric motor 22. The flywheel 190 of FIGS. 18A and 18B includes an inertia ring 190a attached directly to the blades 50 of the fan 46. The blades 50 of the fan 46 thereby also act as spokes, holding the mass of the inertia ring 190 at a radial distance from the axis of rotation A. The blades 50 may be made of a relatively lightweight material, such as aluminum or plastic, while the inertia ring may be made of a relatively heavy material, such as steel or copper. As is apparent from FIG. 18A, the inertia ring 190a extends 100% of the total radius of the flywheel 190, i.e., defines the radially outermost rim of the flywheel 190. While Figures 18A and 18B show a combined fan 46 and flywheel 190, it will be apparent that weight may also be added to the radially outermost portions of the other rotating components of the transmission arrangement 28 to increase the moment of inertia of the transmission arrangement without unduly increasing the tare weight of the transmission arrangement.

[0110] Figure 19 shows a computer readable storage medium provided as a CD (Compact Disc) 99. The CD 99 stores a computer program product comprising instructions for performing any of the methods defined above when the program is executed on a processor.

[0111] The present invention has been described above primarily with reference to certain embodiments, however, as those skilled in the art will readily appreciate, embodiments other than those disclosed above are equally possible within the scope of the present invention, as defined by the appended claims.

[0112] For example, the present invention has been described with reference to a rear-handle type chainsaw, however, it will be understood that the teachings herein are equally applicable to top-handle type chainsaws.

[0113] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. [Appendix 1] an electric motor (22); a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); In handheld battery-powered chainsaws (10;110), including a transmission arrangement (28; 128; 228; 328; 428) including a slip clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16), the slip clutch (34; 234; 334; 434) being configured to at least partially disengage the electric motor (22) from the saw chain (16) by allowing slippage in engagement between the drive element (36; 236; 336; 436) and the driven member (38; 238; 338; 438). [Appendix 2] A handheld battery-powered chainsaw (10; 110) as described in Appendix 1, wherein the transmission arrangement (28; 128; 228) is configured to achieve a 1:1 transmission ratio between the electric motor (22) and a saw chain sprocket that meshes with the saw chain (16). [Appendix 3] 3. The handheld battery-powered chainsaw (10; 110) according to claim 1 or 2, wherein the slip clutch is configured to transmit a slip torque of between 2 Nm and 4.5 Nm while slipping. [Appendix 4] 4. A handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 3, wherein the slip clutch (34; 234; 334; 434) is movable between an engaged state, in which the slip clutch (34; 234; 334; 434) is configured to drive the saw chain (16), and a disengaged state, in which the drive element (36; 236; 336; 436) is free to rotate without driving the saw chain (16). [Appendix 5] The slip clutch (34; 234; 334; 434) operates at a rotational speed (ω C1 5. The handheld battery-powered chainsaw (10; 110) of claim 4, configured to transition between the engaged state and the disengaged state in response to a change in [Appendix 6] The slip clutch (34; 234; 334; 434) adjusts the rotational speed (ω C1 6. The handheld battery-powered chainsaw (10; 110) of any one of appendices 1 to 5, configured to transition between a slippable state in which the drive element (36; 236; 336; 436) can slip relative to the driven member (38; 238; 338; 438) in response to a change in torque, and a lock-up state in which the slip clutch (34; 234; 334; 434) is configured to drive the saw chain (16) without slipping. [Appendix 7] The slip clutch (34; 234; 334; 434) operates at a predetermined clutch engagement speed (ω E ) and configured to transition between the disengaged and engaged states at a clutch engagement speed (ω E ), the slip clutch (34; 234; 334; 434) assumes the engaged state, The slip clutch (34; 234; 334; 434) operates at a predetermined slip limit speed (ω L ), the slip limit speed (ω L ), the slip clutch (34; 234; 334; 434) assumes the lockup state, The slip limit speed (ω L ) is the clutch engagement speed (ω E ) at least 200 rpm higher than the speed of the handheld battery-powered chainsaw (10; 110) according to appendix 6 in combination with appendix 4 or 5. [Appendix 8] 8. The handheld battery-powered chainsaw (10; 110) according to any one of appendices 1 to 7, wherein the slip clutch (34) is inertia-operated. [Appendix 9] The handheld battery-powered chainsaw (10; 110) according to any one of appendices 4 to 8, wherein the slip clutch is configured as a centrifugal clutch (34). [Appendix 10] 10. A handheld battery-powered chainsaw (10; 110) according to claim 9, wherein the driven member comprises a clutch drum (38) having a diameter of 60 mm to 90 mm, and the drive element (36) comprises two or three, preferably a set of two, friction shoes (68a, 68b) elastically connected to each other by elastic elements (70a, 70b), each of the friction shoes (68a, 68b) having an individual weight of 30 g to 70 g, and each of the elastic elements (70a, 70b) having a spring constant of 35 N / mm to 60 N / mm. [Appendix 11] the slip clutch (34; 234; 334; 434) has a proximal end (34b) facing the electric motor (22) and a distal end (34a) facing away from the electric motor (22); 11. A handheld battery-powered chainsaw (110) according to any one of appendices 1 to 10, wherein the saw chain drive sprocket (32) is connected to the driven member (38; 238; 338; 438) of the slip clutch (34; 234; 334; 434) at the tip side (34a) of the slip clutch (34; 234; 334; 434). [Appendix 12] the slip clutch (34; 234; 334; 434) has a proximal end (34b) facing the electric motor (22) and a distal end (34a) facing away from the electric motor (22); A handheld battery-powered chainsaw (10) according to any one of appendices 1 to 11, wherein a saw chain drive sprocket (32) is connected to the driven member (38; 238; 338; 438) of the slip clutch (34; 234; 334; 434) at the base end side of the slip clutch (34; 234; 334; 434). [Appendix 13] The electric motor (22) a rotor (54) configured to be rotated by the stator (52), the rotor (54) having a rotor outer diameter (D1); an output shaft (30) drivingly connected to the drive element (36; 236; 336; 436) of the slip clutch (34; 234; 334; 434), the output shaft (30) having a shaft diameter (D2); and A handheld battery-powered chainsaw (10; 110) according to any one of appendices 1 to 12, wherein the ratio (D1 / D2) of the rotor outer diameter (D1) to the shaft diameter (D2) is 2.5 to 4.8. [Appendix 14] 8. The handheld battery-powered chainsaw (10; 110) according to any one of appendices 1 to 7, wherein the slip clutch (134) is electromagnetically actuated based on a clutch control signal. [Appendix 15] 15. A handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 14, further comprising a mechanical brake arrangement (40a, 40b) movable between a brake position in which the mechanical brake arrangement (40a, 40b) is configured to engage the transmission arrangement (28; 128; 228; 328; 428) to brake the rotation of the driven member (38; 238; 338; 438), and a release position in which the driven member (38; 238; 338; 438) is free to rotate. [Appendix 16] 16. The handheld battery-powered chainsaw (10; 110) of claim 15, further comprising a rear handle (14b) provided with a trigger (24) for operating the electric motor (22), wherein the mechanical brake arrangement is configured to operate independently of the position of the trigger (24). [Appendix 17] 17. The handheld battery-powered chainsaw (10; 110) of claim 15 or 16, wherein the driven member includes a clutch drum (38), and the mechanical brake arrangement (40a, 40b) includes a brake band (40b) configured to apply a clamping force to a radially outer surface of the clutch drum (38) in response to actuation of a brake actuator (25). [Appendix 18] 18. A handheld battery-powered chainsaw (10; 110) according to any one of appendices 15 to 17, wherein the mechanical brake arrangement (40a, 40b) includes a brake drum (40a) axially separated from the slip clutch (34; 234; 334; 434) and a brake band (40b) configured to apply a clamping force to a radially outer surface of the brake drum (38) in response to actuation of a brake actuator (25). [Appendix 19] The handheld battery-powered chainsaw (10; 110) according to any one of appendices 1 to 18, further comprising an electrically controlled brake (23e), such as an electromagnetic brake and / or an induction brake. [Appendix 20] 19. A handheld battery-powered chainsaw (10; 110) according to claim 19, wherein the electrically controlled brake (23e) is configured to apply a braking force to the drive element side of the slip clutch, i.e., to one or more of the electric motor (22), the drive element (36; 236; 336; 436), and an element fixedly attached to the electric motor (22) or the drive element (36; 236; 336; 436). [Appendix 21] The battery-powered chainsaw (10; 110) has a rotation speed (ω m ) is the electric brake release speed (ω R 21. The handheld battery-powered chainsaw (10; 110) of claim 19 or 20, configured to release the electrically controlled brake (23e) in response to a load falling below a predetermined value. [Appendix 22] 22. A handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 21, wherein the electric motor (22) includes a rotor (54) configured to rotate about a motor axis of rotation (A), and the drive element (36; 236; 336; 436) is rotationally locked to rotationally engage with the rotor, preventing rotation of the drive element (36; 236; 336; 436) in both directions of rotation about the motor axis of rotation (A). [Appendix 23] 23. The handheld battery-powered chainsaw (10; 110) of any one of claims 1 to 22, further comprising a cooling fan (46) coupled to operate constantly with the drive element side of the slip clutch (34; 234; 334; 434). [Appendix 24] 24. The handheld battery-powered chainsaw (10; 110) of claim 23, wherein the slip clutch (34; 234; 334; 434) is positioned on a first axial side (44a) of the electric motor (22), and the cooling fan (46) is positioned on a second axial side (44b) of the electric motor (22) opposite the first axial side (44a). [Appendix 25] The handheld battery-powered chainsaw (10; 110) of any one of appendices 1 to 24, further comprising a saw chain oil pump coupled to receive power from the driven member (38; 238; 338; 438) side of the slip clutch (34; 234; 334; 434). [Appendix 26] A handheld battery-powered chainsaw (10; 110) according to any one of appendices 1 to 25, further comprising a control device (23) configured to operate the slip clutch (34; 234; 334; 434) between an engaged state, in which the slip clutch (34; 234; 334; 434) is configured to drive the saw chain (16), and a disengaged state, in which the drive element (36; 236; 336; 436) is free to rotate without driving the saw chain (16). [Appendix 27] 27. The handheld battery-powered chainsaw (10; 110) of claim 26, wherein the control device (23) is configured to maintain operation of the electric motor (22) with the slip clutch (34; 234; 334; 434) disengaged. [Appendix 28] 28. The handheld battery-powered chainsaw (10; 110) of claim 27, wherein the control device (23) is configured to operate the cooling fan (46) of the battery-powered chainsaw (10; 110) based on a condition where the detected temperature exceeds a threshold temperature by maintaining operation of the electric motor (22) with the slip clutch (34; 234; 334; 434) disengaged. [Appendix 29] The battery-powered chainsaw (10; 110) further includes a trigger (24) movable between a depressed position and a released position, the electric motor (22) being operated to move the saw chain (16) in response to the trigger (24) being in the depressed position, and the saw chain (16) being stopped in response to the trigger (24) being in the released position; 29. The handheld battery-powered chainsaw (10; 110) of any one of appendices 26 to 28, wherein the control device (23) is configured to enable operation of the electric motor (22) when the trigger (24) is in the released position. [Appendix 30] 29. A handheld battery-powered chainsaw (10; 110) as described in Appendix 29, wherein the control device (23) is configured to enable operation of the electric motor (22) based on the condition that a mechanical brake (40a, 40b) configured to brake the driven member (38; 238; 338; 438) is engaged when the trigger (24) is in the released position. [Appendix 31] The control device (23) is configured to detect excessive clutch slippage, which may be detected, for example, by detecting a slippage limit speed (ω L ) and detecting prolonged operation below the slip limit speed (ω L ), the slip clutch (34; 234; 334; 434) will be in a lock-up state, The control device (23) is configured to vary a control signal for operating the electric motor (22) in response to detecting excessive clutch slip. A handheld battery-powered chainsaw (10;110) according to any one of appendices 26-30. [Appendix 32] Applying the change to the control signal to operate the electric motor (22) increases the torque (T m ) and / or the rotational speed (ω) of the electric motor (22) m ) the handheld battery-powered chainsaw (10;110) described in Appendix 31, including changing the [Appendix 33] The control device (23) controls the torque (T) delivered by the electric motor (22) within a limited time or a limited number of pulses. m ) is pulsed, the rotation speed (ω m ) to the clutch engagement speed (ω E ) below. [Appendix 34] a trigger (24) movable between a depressed position and a released position, the electric motor (22) being operated to move the saw chain (16) in response to the trigger (24) being in the depressed position, and the saw chain (16) being stopped in response to the trigger (24) being in the released position; The control device (23) controls the rotation speed (ω m ) to the clutch engagement speed (ω E ), the slip limit speed (ω ) is maintained until the trigger (24) is released and then pressed again. L ) ) ) ) ). [Appendix 35] 35. The handheld battery-powered chainsaw (10; 110) of any one of appendices 1 to 34, wherein the electric motor (22) is an outrunner including a rotationally fixed stator radially surrounded by a rotor comprising a set of permanent magnets, the rotor having a stator winding. [Appendix 36] 36. The handheld battery-powered chainsaw (10; 110) according to any one of appendices 1 to 35, wherein the electric motor (22) is a vector-controlled permanent magnet motor. [Appendix 37] The control device (23) controls the torque (T) of the electric motor (22) in response to detecting an overload of the electric motor (22). m 37. A handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 36, configured to maintain or increase [Appendix 38] Chainsaw body (12); an elongated guide bar (18) for guiding the saw chain (16), the extension direction of the guide bar defining an axis (X), the guide bar (18) extending in a forward direction along the axis (X) from the front end of the chainsaw body (12), the guide bar (18) extending in a guide bar plane; a front handle (14a); a rear handle (14b), the bottom surface of which is provided with a trigger (24) that enables an operator to operate the electric motor (22); and a plane (P) that is parallel to the guide bar plane and includes a rearmost point (24a) of the trigger (24) intersects with a vertex (B) of the front handle at an intersection point, and a distance (L) between the intersection point (B) and the rearmost point (24a) of the trigger (24) is greater than 270 mm. A handheld battery-powered chainsaw (10; 110) according to any one of appendices 1 to 37, comprising: [Appendix 39] 39. The handheld battery-powered chainsaw (10; 110) of claim 38, wherein the battery-powered chainsaw (10; 110) is configured to operate the electric motor (22) up to a maximum power output (E), and the quotient (L / E) of the distance (L) from the intersection point (B) to the rearmost point (24a) of the trigger (24) and the maximum power output (E) is greater than 0.11 mm / W. [Appendix 40] The battery-powered chainsaw (10; 110) has a motor torque (T m ) and configured to operate the electric motor (22) to generate a The motor torque (T m ) is the slip limit speed (ω L ) at slip torque (T s ) and the distance (L) from the intersection point (B) to the rearmost point (24a) of the trigger (24) and the slip torque (T s ) and the quotient (L / T s ) is greater than 90 mm / Nm. [Appendix 41] an electric motor (22); a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); a control device (23) for operating the electric motor (22); a trigger (24) operably coupled to the control device (23), the trigger (24) being movable between a depressed position and a released position, the control device (23) configured to operate the electric motor (22) to drive the saw chain (16) in response to the trigger (24) being in the depressed position, and the control device (23) configured to stop the driving of the saw chain (16) in response to the trigger (24) being in the released position; and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) includes a clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven element (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16); the clutch (34; 234; 334; 434) is movable between an engaged state in which the clutch (34; 234; 334; 434) engages the electric motor (22) with the saw chain (16) and a disengaged state in which the clutch (34; 234; 334; 434) disengages the electric motor (22) from the saw chain (16) to allow the drive element (36; 236; 336; 436) to rotate freely without driving the saw chain (16); The handheld battery-powered chainsaw (10; 110), wherein the control device (23) is configured to automatically maintain operation of the electric motor (22) in an idle mode with the clutch (34; 234; 334; 434) in the disengaged state when the trigger (24) is in the released position. [Appendix 42] The clutch is a centrifugal clutch (34), and the control device (23) controls the engagement speed (ω E Idle speed (ω) below i ) The handheld battery-powered chainsaw (10; 110) of claim 41, configured to automatically maintain operation of the electric motor (22) in the idle mode. [Appendix 43] The control device (23) controls the idle speed (ω E 43. The handheld battery-powered chainsaw (10; 110) of claim 41 or 42, configured to automatically maintain operation of the electric motor (22) in the idle mode. [Appendix 44] A handheld battery-powered chainsaw (10; 110) according to any one of claims 41 to 43, further comprising a cooling fan (46) coupled to operate constantly with the drive element side of the clutch (34; 234; 334; 434). [Appendix 45] an electric motor (22); a transmission arrangement (128; 528) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (128; 528); a flywheel (90; 190) configured to receive and store angular momentum from the electric motor (22), the flywheel (90; 190) coupled to rotate with at least a portion of the transmission arrangement (28) about a flywheel axis of rotation (A); including handheld battery-powered chainsaws (10;110). [Appendix 46] an electric motor (22) including a rotor (54) configured to rotate about a motor axis of rotation (A); a plurality of components (30, 32, 34, 40a, 42a, 46, 90) configured to be rotated by the electric motor (22) around the motor rotation axis (A); In handheld battery-powered chainsaws (10;110), including The sum of the inertia moments J of the rotor (54) and all components (30, 32, 34, 40a, 42a, 46, 90) configured to be rotated around the motor rotation axis (A) by the electric motor (22) is 1.5*10 -4 kgm 2 A handheld battery-powered chainsaw that is characterized by exceeding (10; 110). [Appendix 47] an electric motor (22) including a rotor (54) configured to rotate about a motor axis of rotation (A); a plurality of components (30, 32, 34, 40a, 42a, 46, 90) configured to be rotated around the motor rotation axis (A) by the electric motor (22); In handheld battery-powered chainsaws (10;110), including The quotient J / M of the total moment of inertia J of the rotor (54) and all components (30, 32, 34, 40a, 42a, 46, 90) configured to be rotated around the motor rotation axis (A) by the electric motor (22) and the total mass M of the rotor (54) and all components (30, 32, 34, 40a, 42a, 46, 90) configured to be rotated around the motor rotation axis (A) by the electric motor (22) is 3.6*10 -4 m 2 A handheld battery-powered chainsaw that is characterized by exceeding (10; 110). [Appendix 48] 1. A method of controlling an electric motor (22) for selectively driving a saw chain (16) in a chain saw (10; 110) including a trigger (24) for initiating rotation of the saw chain (16), comprising: operating the electric motor (22) before detecting depression of the trigger (24); moving the saw chain (16) in response to detecting depression of the trigger (24); A method comprising: [Appendix 49] Mechanically engaging the electric motor (22) with the saw chain (16) increases the rotational speed (ω m ) to the clutch engagement speed (ω E 49. The method of claim 48, comprising increasing the concentration of hydroxybenzoates to 100%. [Appendix 50] 1. A method of controlling an electric motor (22) for selectively driving a saw chain (16) in a chain saw (10; 110) including a trigger (24) for initiating rotation of the saw chain (16), comprising: operating the saw chain (16) in response to detecting depression of the trigger (24); responsive to detecting release of the trigger (24), stopping operation of the saw chain (16); maintaining operation of the electric motor (22) after stopping operation of the saw chain (16); A method comprising: [Appendix 51] Mechanically disengaging the electric motor (22) from the saw chain (16) reduces the rotational speed (ω m ) to the clutch engagement speed (ω E 51. The method of claim 50, comprising reducing the [Appendix 52] 1. A method of controlling an electric motor (22) for selectively driving a saw chain (16) in a chain saw (10; 110), comprising: In response to detecting depression of the trigger (24), the electric motor (22) is rotated at a first rotational speed (ω m ) and; In response to detecting the release of the trigger (24), the electric motor (22) is rotated at a second rotational speed (ω i ) and A method comprising: [Appendix 53] 1. A method of controlling an electric motor (22) for selectively driving a saw chain (16) in a chain saw (10; 110) including a clutch (34; 234; 334; 434), comprising: determining a clutch state, which is a state of the clutch (34; 234; 334; 434); Based on the determined clutch state, the torque (T m ) or rotation speed (ω m ) and / or generating an alert to the operator of said chainsaw (10; 110); A method comprising: [Appendix 54] Determining the state of the clutch (34; 234; 334; 434) involves determining the current rotational speed (ω m ;ω C1 ;ω C2 54. The method of claim 53, comprising determining [Appendix 55] the clutch state is a slip state, The torque (T m ) or rotation speed (ω m ) is adjusted to adjust the rotation speed (ω m ) to the clutch engagement speed (ω E ) and / or the torque (T m 55. The method of claim 53 or 54, comprising reducing [Appendix 56] the clutch state is a slip state, The torque (T m ) or rotation speed (ω m ) of the electric motor (22) m 56. The method of any one of appendices 53 to 55, comprising increasing [Appendix 57] 1. A method of controlling an electric motor (22) for selectively driving a saw chain (16) in a chain saw (10; 110), comprising: Current rotation speed (ω m ;ω C1 ;ω C2 ) and; activating an electromechanical clutch (234; 334; 434) based on said determination; A method comprising: [Appendix 58] 58. The method of claim 57, further comprising receiving a clutch engage speed setting and / or a clutch disengage speed setting from a user interface (27). [Appendix 59] A data processing device (23) including at least one processor and memory configured to carry out the method according to any one of claims 48 to 58. [Appendix 60] A computer program product comprising instructions which, when executed on a processor, perform the method of any one of claims 48 to 58. [Appendix 61] A computer-readable storage medium (99) having stored thereon the computer program product of claim 60.

Claims

1. an electric motor (22); a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) comprises a slip clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16), the slip clutch (34; 234; 334; 434) being configured to at least partially disengage the electric motor (22) from the saw chain (16) by allowing slip in engagement between the drive element (36; 236; 336; 436) and the driven member (38; 238; 338; 438); the slip clutch (34; 234; 334; 434) is configured to transition between a disengaged state and an engaged state at a predetermined clutch engagement speed (ω E ), above which the slip clutch (34; 234; 334; 434) assumes the engaged state; The handheld battery-powered chainsaw (10; 110) further comprises a cooling fan (46) coupled to operate constantly with the drive element side of the slip clutch (34; 234; 334; 434).

2. 2. A handheld battery-powered chainsaw (10; 110) as described in claim 1, wherein the transmission arrangement (28; 128; 228) is configured to achieve a 1:1 transmission ratio between the electric motor (22) and a saw chain sprocket that meshes with the saw chain (16).

3. A handheld battery-powered chainsaw (10; 110) according to claim 1 or 2, wherein the slip clutch is configured to transmit a slip torque of between 2 Nm and 4.5 Nm while slipping.

4. 2. A handheld battery-powered chainsaw (10; 110) as described in claim 1, wherein the slip clutch (34; 234; 334; 434) is movable between an engaged state in which the slip clutch (34; 234; 334; 434) is configured to drive the saw chain (16) and a disengaged state in which the drive element (36; 236; 336; 436) is free to rotate without driving the saw chain (16).

5. A handheld battery-powered chainsaw (10; 110) as described in claim 1, wherein the slip clutch (34; 234; 334; 434) is positioned on a first axial side (44a) of the electric motor (22), and the cooling fan (46) is positioned on a second axial side (44b) of the electric motor (22) opposite the first axial side (44a).

6. The slip clutch (34; 234; 334; 434) adjusts the rotational speed (ω) of the drive element (36; 236; 336; 436). Ｃ１ 2. The handheld battery-powered chainsaw (10; 110) of claim 1, wherein the drive element (36; 236; 336; 436) is configured to transition between a slippable state in which the drive element (36; 236; 336; 436) can slip relative to the driven member (38; 238; 338; 438) and a lock-up state in which the slip clutch (34; 234; 334; 434) is configured to drive the saw chain (16) without slipping, in response to a change in the drive element (36; 236; 336; 436).

7. the slip clutch (34; 234; 334; 434) is movable between an engaged state, in which the slip clutch (34; 234; 334; 434) is configured to drive the saw chain (16), and a disengaged state, in which the drive element (36; 236; 336; 436) is free to rotate without driving the saw chain (16); The slip clutch (34; 234; 334; 434) operates at a predetermined slip limit speed (ω Ｌ ), the slip limit speed (ω Ｌ ), the slip clutch (34; 234; 334; 434) assumes the lock-up state, The slip limit speed (ω Ｌ ) is the clutch engagement speed (ω Ｅ 7. The handheld battery-powered chainsaw (10; 110) of claim 6, wherein the rotational speed is at least 200 rpm higher than the rotational speed of the power supply.

8. 2. The handheld battery-powered chainsaw (10; 110) of claim 1, wherein the slip clutch (34) is inertia operated.

9. The handheld battery-powered chainsaw (10; 110) according to any one of claims 4 to 8, wherein the slip clutch is configured as a centrifugal clutch (34).

10. 10. A handheld battery-powered chainsaw (10; 110) according to claim 9, wherein the driven member comprises a clutch drum (38) having a diameter of 60 mm to 90 mm, and the drive element (36) comprises a set of two or three friction shoes (68a, 68b) elastically connected to each other by elastic elements (70a, 70b), each of the friction shoes (68a, 68b) having an individual weight of 30 g to 70 g, and each of the elastic elements (70a, 70b) having a spring constant of 35 N / mm to 60 N / mm.

11. An electric motor (22), a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) comprises a slip clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16), the slip clutch (34; 234; 334; 434) being configured to at least partially disengage the electric motor (22) from the saw chain (16) by allowing slip in engagement between the drive element (36; 236; 336; 436) and the driven member (38; 238; 338; 438); the slip clutch (34; 234; 334; 434) is configured to transition between a disengaged state and an engaged state at a predetermined clutch engagement speed (ω E ), above which the slip clutch (34; 234; 334; 434) assumes the engaged state; the slip clutch (34; 234; 334; 434) has a proximal side (34b) facing the electric motor (22) and a distal side (34a) facing away from the electric motor (22); A handheld battery-powered chainsaw (110) in which a saw chain drive sprocket (32) is connected to the driven member (38; 238; 338; 438) of the slip clutch (34; 234; 334; 434) at the tip side (34a) of the slip clutch (34; 234; 334; 434).

12. An electric motor (22), a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) comprises a slip clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16), the slip clutch (34; 234; 334; 434) being configured to at least partially disengage the electric motor (22) from the saw chain (16) by allowing slip in engagement between the drive element (36; 236; 336; 436) and the driven member (38; 238; 338; 438); the slip clutch (34; 234; 334; 434) is configured to transition between a disengaged state and an engaged state at a predetermined clutch engagement speed (ω E ), above which the slip clutch (34; 234; 334; 434) assumes the engaged state; the slip clutch (34; 234; 334; 434) has a proximal side (34b) facing the electric motor (22) and a distal side (34a) facing away from the electric motor (22); A handheld battery-powered chainsaw (10) in which a saw chain drive sprocket (32) is connected to the driven member (38; 238; 338; 438) of the slip clutch (34; 234; 334; 434) on the proximal end side of the slip clutch (34; 234; 334; 434).

13. An electric motor (22), a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) comprises a slip clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16), the slip clutch (34; 234; 334; 434) being configured to at least partially disengage the electric motor (22) from the saw chain (16) by allowing slip in engagement between the drive element (36; 236; 336; 436) and the driven member (38; 238; 338; 438); the slip clutch (34; 234; 334; 434) is configured to transition between a disengaged state and an engaged state at a predetermined clutch engagement speed (ω E ), above which the slip clutch (34; 234; 334; 434) assumes the engaged state; The electric motor (22) a rotor (54) configured to be rotated by the stator (52), the rotor (54) having a rotor outer diameter (D1); an output shaft (30) drivingly connected to the drive element (36; 236; 336; 436) of the slip clutch (34; 234; 334; 434), the output shaft (30) having a shaft diameter (D2); and A handheld battery-powered chainsaw (10; 110), wherein the ratio (D1 / D2) of the rotor outer diameter (D1) to the shaft diameter (D2) is 2.5 to 4.

8.

14. 2. The handheld battery-powered chainsaw (10; 110) of claim 1, wherein the slip clutch (134) is electromagnetically actuated based on a clutch control signal.

15. An electric motor (22), a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) comprises a slip clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16), the slip clutch (34; 234; 334; 434) being configured to at least partially disengage the electric motor (22) from the saw chain (16) by allowing slip in engagement between the drive element (36; 236; 336; 436) and the driven member (38; 238; 338; 438); the slip clutch (34; 234; 334; 434) is configured to transition between a disengaged state and an engaged state at a predetermined clutch engagement speed (ω E ), above which the slip clutch (34; 234; 334; 434) assumes the engaged state; The handheld battery-powered chainsaw (10; 110) further includes a mechanical brake arrangement (40a, 40b) movable between a brake position in which the mechanical brake arrangement (40a, 40b) engages the transmission arrangement (28; 128; 228; 328; 428) to brake rotation of the driven member (38; 238; 338; 438), and a release position in which the driven member (38; 238; 338; 438) is free to rotate.

16. 16. A handheld battery-powered chainsaw (10; 110) as claimed in claim 15, further comprising a rear handle (14b) provided with a trigger (24) for operating the electric motor (22), wherein the mechanical brake arrangement is configured to operate independently of the position of the trigger (24).

17. 17. A handheld battery-powered chainsaw (10; 110) as claimed in claim 15 or 16, wherein the driven member includes a clutch drum (38), and the mechanical brake arrangement (40a, 40b) includes a brake band (40b) configured to apply a clamping force to a radially outer surface of the clutch drum (38) in response to actuation of a brake actuator (25).

18. 16. A handheld battery-powered chainsaw (10; 110) as described in claim 15, wherein the mechanical brake arrangement (40a, 40b) includes a brake drum (40a) axially separated from the slip clutch (34; 234; 334; 434) and a brake band (40b) configured to apply a clamping force to a radially outer surface of the brake drum (38) in response to actuation of a brake actuator (25).

19. An electric motor (22); a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) comprises a slip clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16), the slip clutch (34; 234; 334; 434) being configured to at least partially disengage the electric motor (22) from the saw chain (16) by allowing slip in engagement between the drive element (36; 236; 336; 436) and the driven member (38; 238; 338; 438); the slip clutch (34; 234; 334; 434) is configured to transition between a disengaged state and an engaged state at a predetermined clutch engagement speed (ω E ), above which the slip clutch (34; 234; 334; 434) assumes the engaged state; The handheld battery-powered chainsaw (10; 110) further includes a saw chain oil pump coupled to receive power from the driven member (38; 238; 338; 438) side of the slip clutch (34; 234; 334; 434).

20. an electric motor (22); a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); a control device (23) for operating the electric motor (22); a trigger (24) operably coupled to the control device (23), the trigger (24) being movable between a depressed position and a released position, the control device (23) configured to operate the electric motor (22) to drive the saw chain (16) in response to the trigger (24) being in the depressed position, and the control device (23) configured to stop the driving of the saw chain (16) in response to the trigger (24) being in the released position; and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) includes a clutch (34; 234; 334; 434) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven element (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16); the clutch (34; 234; 334; 434) is movable between an engaged state in which the clutch (34; 234; 334; 434) engages the electric motor (22) with the saw chain (16) and a disengaged state in which the clutch (34; 234; 334; 434) disengages the electric motor (22) from the saw chain (16) to allow the drive element (36; 236; 336; 436) to rotate freely without driving the saw chain (16); the clutch (34; 234; 334; 434) is configured to transition between the disengaged state and the engaged state at a predetermined clutch engagement speed (ω E ), above which the clutch (34; 234; 334; 434) assumes the engaged state; The handheld battery-powered chainsaw (10; 110), wherein the control device (23) is configured to automatically maintain operation of the electric motor (22) in an idle mode with the clutch (34; 234; 334; 434) in the disengaged state when the trigger (24) is in the released position.

21. An electric motor (22); a transmission arrangement (28; 128; 228; 328; 428) coupled to the electric motor (22), the electric motor (22) being configured to drive a saw chain (16) via the transmission arrangement (28; 128; 228; 328; 428); a control device (23) for operating the electric motor (22); a trigger (24) operably coupled to the control device (23), the trigger (24) being movable between a depressed position and a released position, the control device (23) configured to operate the electric motor (22) to drive the saw chain (16) in response to the trigger (24) being in the depressed position, and the control device (23) configured to stop the driving of the saw chain (16) in response to the trigger (24) being in the released position; and A handheld battery-powered chainsaw (10; 110) comprising: the transmission arrangement (28; 128; 228; 328; 428) includes a centrifugal clutch (34) including a drive element (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 238; 338; 438) configured to transmit rotational power to the saw chain (16); the centrifugal clutch (34) is movable between an engaged state in which the centrifugal clutch (34) engages the electric motor (22) with the saw chain (16) and a disengaged state in which the centrifugal clutch (34) disengages the electric motor (22) from the saw chain (16) to allow the drive element (36; 236; 336; 436) to rotate freely without driving the saw chain (16); a control device (23) configured to automatically maintain operation of the electric motor (22) in an idle mode with the centrifugal clutch (34) in the disengaged state when the trigger (24) is in the released position; The control device (23) controls the engagement speed (ω Ｅ Idle speed (ω) below ｉ ) A handheld battery-powered chainsaw (10; 110) configured to automatically maintain operation of the electric motor (22) in the idle mode.

22. The control device (23) controls the idle speed (ω Ｅ 22. A handheld battery-powered chainsaw (10; 110) according to claim 20 or 21, configured to automatically maintain operation of the electric motor (22) in the idle mode.

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