Chain saw, method of controlling a chain saw, and computer program implementing the method

Abstract

A hand-held battery-powered chainsaw includes a motor (22) and a transmission (28) coupled to the motor (22), wherein the motor (22) is configured to drive a saw chain via the transmission (28). The transmission (28) includes a slip clutch (34) including a drive member (36) configured to receive rotational power from the motor (22) and a driven member (38) configured to transmit rotational power to the saw chain (16), wherein the slip clutch (34) is configured to at least partially decouple the motor (22) from the saw chain by enabling slippage when engaged between the drive member (36) and the driven member (38).

Description

Technical Field

[0001] This invention relates to a handheld battery-powered chainsaw, a method for controlling such chainsaw, a computer program product for implementing such method, and a data carrier for storing the computer program product. Background Technology

[0002] Chainsaws have been known for approximately 100 years. Due to the relationship between weight, power, and operating time, most chainsaws are still powered by two-stroke internal combustion engines, but battery-powered chainsaws are becoming increasingly popular. However, achieving high output power, high cutting efficiency, and high availability without compromising other aspects of the chainsaw, such as weight or battery life, remains a challenge. Furthermore, continuous efforts are being made to make chainsaws safer and easier to use. Summary of the Invention

[0003] The object of this invention is to solve or at least mitigate some or all of the aforementioned problems. To this end, a handheld battery-powered chainsaw is provided, comprising an electric motor and a transmission coupled to the electric motor, wherein the electric motor is configured to drive a saw chain via the transmission, wherein the transmission includes a slip clutch comprising a drive member configured to receive rotational power from the electric motor and a driven member configured to transmit the rotational power to the saw chain, wherein the slip clutch is configured to at least partially disengage the electric motor from the saw chain by allowing slippage when engaged between the drive member and the driven member. The slip clutch can be a mechanical clutch, such as a centrifugal clutch, a band clutch, a selectively engaged idler pulley, 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 enter, a state that allows the drive member and the driven member to slide relative to each other, thereby transmitting torque via slip engagement, wherein the transmitted torque is sufficient to drive the saw chain if it is not loaded. Upon initiation of movement, the gradual slip engagement of the clutch enables a gradual increase in power transmission without any decrease in the speed of the electric motor. This makes it easier to (re)start the chain once it's engaged with the material to be cut, as the torque won't drop in response to the speed falling to zero. Furthermore, the inertia established by the motor's rotor can aid in starting the chain. Going further, the slipper clutch provides soft engagement with the chain, resulting in an improved general user experience. The slipper clutch can also provide feedback to the user when the saw chain is overloaded, for example by the user pressing the chain too tightly against the material to be cut, as it's very easy to hear when the clutch is slipping, for many clutch types. Auditory and / or tactile feedback can prompt the user to release the load, and taking advantage of the high torque from the motor at low speeds, the motor directly restarts the chain, immediately bringing the chainsaw back to high cutting efficiency. When slipping, the motor won't stop even if the operator presses the saw chain too hard against the material to be cut. Going further, some motor types only provide low to medium torque when stationary, while the torque reaches its maximum at very low speeds. Thus, the slipper clutch allows for greater freedom in selecting the type of motor. The handheld battery-powered chainsaw may further include a finger-operated trigger coupled to an electrical switch for selectively operating the electric motor. The trigger may be configured to operate the motor in steps or continuously over a range of output power, rotational speed, and / or output torque; alternatively, the trigger may be configured for simple on / off control of the motor. According to one embodiment, the drive member 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 chain drive sprocket for driving the saw chain.According to another embodiment, the drive member may be rigidly connected to the output shaft of the electric motor, and / or the driven member may be rigidly connected to the saw chain drive member, such as a saw chain drive sprocket or a key shaft configured to mate with the rim of the saw chain drive sprocket. According to another embodiment, 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 connect to, for example, a backpack battery. A typical suitable DC battery voltage range for supplying power to the electric motor may be between 18V and 100V, more preferably between approximately 36V and approximately 72V. The electric motor may be configured to provide output power within an exemplary power range, for example, 1.8kW to 3.5kW.

[0004] According to one embodiment, the transmission device can be configured to provide a 1:1 transmission ratio between the electric motor and the saw chain sprocket that cooperates with the saw chain. Here, a 1:1 transmission ratio means that if the drive member is rotatably locked to the driven member in a non-slip manner, one full revolution of the electric motor corresponds to one full revolution of the saw chain sprocket. According to one embodiment, the saw chain sprocket can be coaxial with the output shaft of the electric motor.

[0005] According to one embodiment, the slip clutch can be configured to transmit a slip torque between 2 Nm and 4.5 Nm during slippage. This torque range has been found to be very suitable for handheld battery-powered chainsaws. According to some embodiments, the slip clutch can be configured to transmit a slip torque between 2 Nm and 3 Nm during slippage.

[0006] According to the implementation, the slip clutch can move between an engaged state and a disengaged state. In the engaged state, the slip clutch is configured to drive the saw chain; in the disengaged state, the drive member can rotate freely without driving the saw chain. This allows the use of a lower-cost electric motor. For example, vector-controlled brushless DC motors typically include a rotor position sensor to sense the precise rotor position in the motor, enabling the motor to be started in the desired positive direction. The disengaged state allows the rotor position sensor to be omitted. A lack of information about the rotor position could lead to unintentional starting of the motor in the opposite direction. After an initial movement in the reverse direction, vector control would then automatically reverse the motor to the positive direction. In the disengaged state, this reversal of direction can be passed unnoticed by the operator, as it can be done without moving the chain.

[0007] According to the implementation, the slipper clutch can be configured to switch between an engaged and disengaged state in response to changes in rotational speed. When using a handheld chainsaw, the chain will work, but the operator typically applies some force to achieve the best possible cutting efficiency. If too much force is applied, the chainsaw will eventually stop due to its torque limitation. For gasoline chainsaws, there is an audible warning when the engine load is too high, and the operator can undo the applied force to stop the engine from running. However, when the electric motor is overloaded, it typically stops in a more abrupt and sudden manner, and usually without any substantial audible, visual, or tactile warning. This is frustrating for the user, who needs to release the pressure on the chainsaw before being able to continue cutting. This stop can also cause the saw chain to be squeezed, for example, when felling trees. Therefore, as is generally known to chainsaw operators in the art, unplanned stops can even lead to potentially dangerous situations. However, using a speed-actuated clutch on an electric chainsaw can prevent sudden and unexpected stops under high loads, such as when cutting large logs. Furthermore, the distinguishable engagement state or engagement speed of the clutch makes it easier for the user to notice overload conditions and back off before cutting efficiency is significantly affected, without causing the motor to stop completely and abruptly. Typical motors, characterized by relatively high torque over a low to medium speed range, are particularly well-suited for restarting the chain, for example, during felling. For example, the slipper clutch can be an electromechanical clutch, and the chainsaw can include a controller configured to engage the electromechanical clutch based on the detected motor speed. Alternatively, the slipper clutch can be strictly mechanically actuated, for example, by the inertia of the transmission. According to embodiments, the slipper clutch can be configured to transition between a disengaged and engaged state at a clutch engagement speed above which the clutch is engaged. The clutch engagement speed can be predetermined. For example, it can be set as a control value in the chainsaw's controller, or it can be determined by the mechanical design of a centrifugal clutch. Exemplary suitable engagement speeds for the slipper clutch can be between 2000 rpm and 7000 rpm, more preferably between 3000 rpm and 6000 rpm, and even more preferably between 4500 rpm and 5800 rpm. A slipper clutch can be actuated, for example, in response to changes in the rotational speed of an electric motor and / or drive components.

[0008] According to an embodiment, the slip clutch can be configured to transition between a slip-allowing state and a locked state in response to changes in the rotational speed of the drive member. In the slip-allowing state, the drive member can slide relative to the driven member; in the locked state, the slip clutch is configured to drive the saw chain without slipping. According to an embodiment, the slip clutch can be configured to transition from the slip-allowing state to the locked state at a predetermined slip limit speed above which the slip clutch is locked. The slip clutch can be actuated, for example, in response to changes in the rotational speed of the motor and / or the drive member to transition between the slip-allowing state and the locked state. The slip limit speed is defined as the slip torque of the clutch, i.e., the rotational speed at which the torque required to make the drive member slide relative to the driven member exceeds the motor torque. Typically, for example, for a centrifugal clutch, the slip torque of the clutch increases with the rotational speed of the drive member. Therefore, if the driven member is firmly held in a non-rotating position when operating the chainsaw, the slip limit speed will also be the speed exhibited by the drive member. Therefore, the slip limit speed is higher than any engagement speed as defined above. An exemplary suitable slip limit speed for a slipper clutch can be between 3500 rpm and 7500 rpm, and more preferably between 5500 rpm and 7000 rpm. According to an embodiment, at the slip limit speed, the slip torque is between 2 Nm and 4.5 Nm. More preferably, at the slip limit speed, the slip torque is between 2 Nm and 3 Nm.

[0009] According to one embodiment, the slipper 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. The slipper clutch can also be configured to transition from a slip-allowed state to a locked state at a predetermined slip limit speed, above which the slipper clutch is locked, wherein the slip limit speed is at least 200 rpm higher than the engagement speed. This ensures a smooth transition between the disengaged and locked states. Sudden engagement of the slipper clutch can abruptly decelerate the motor rotor, inducing current spikes in the motor windings. This can lead to overheating of the windings and / or voltage spikes or arcing that could damage, for example, drive electronics. For example, the stator windings of a brushless DC motor are typically of the so-called air-gap winding type, with limited convective heat transfer capabilities. According to another 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.

[0010] According to the implementation, the slipper clutch can be inertial actuated. Therefore, the slipper clutch can be actuated, i.e., transitioned between an engaged and disengaged state by the inertia of a suitable part of the transmission, and / or transitioned between a slippery state and a locked state. For example, the slipper clutch can be implemented as a centrifugal clutch. The slipper clutch can also be actuated by a clutch actuation mechanism similar to an inertial drive (Bendix drive).

[0011] According to one embodiment, the slipper clutch can be configured as a centrifugal clutch. The driven member can be configured as a clutch drum, and the driving member can include one or more friction pads configured to optionally resist elastic bias and move radially in response to rotation of the driving member to engage a radially inwardly facing surface of the clutch drum. The clutch drum can be rotatably mounted in a bearing on the output shaft of the electric motor.

[0012] According to one embodiment, the driven member may include a clutch drum with a diameter between 60 mm and 90 mm, and the driving member may include a set of two or three friction pads, preferably two friction pads, which are elastically connected to each other by elastic elements, wherein each friction pad has a corresponding weight between 30 g and 70 g, and each elastic element 70a, 70b has a spring constant between 35 N / mm and 60 N / mm. It has been found that torque transmission at the slip limit speed of such a clutch is particularly well adapted to the behavior of an electric motor within a typical torque range suitable for a battery-powered chainsaw. A slightly more preferred range for the diameter of the clutch drum is between 65 mm and 82 mm. Alternatively or additionally, a slightly more preferred range for the weight of each corresponding friction pad is between 40 g and 60 g. Alternatively or additionally, a slightly more preferred range for the spring constant of each elastic element is between 60 N / mm and 50 N / mm. According to another embodiment, the product of the clutch drum diameter and the total weight of the set of friction pads is between 5000 g*mm and 10000 g*mm.

[0013] According to one embodiment, the slip clutch may have a proximal side facing the electric motor and a distal side facing away from the electric motor, wherein the saw chain drive sprocket is connected to the driven member of the slip clutch on the distal side of the slip clutch. This arrangement facilitates access to the saw chain drive sprocket, which in turn facilitates, for example, the replacement of the saw chain. According to another embodiment, the driven member may be a clutch drum. The clutch drum may open towards the proximal side to allow the drive member to be received via the proximal side.

[0014] According to an alternative embodiment, the slip clutch may have a proximal side facing the motor and a distal side facing away from the motor, wherein the saw chain drive sprocket is connected to the driven member of the slip clutch on the proximal side of the slip clutch. This arrangement positions the chain drive sprocket closer to the lateral center of the chainsaw, which can be particularly well-suited for compact chainsaws. According to an embodiment, the driven member may be a clutch drum. The clutch drum may open distally to allow the drive member to be received distally. Furthermore, the clutch drum orientation can be conveniently combined with a separate brake drum for braking the driven side of the transmission on the proximal side of the clutch drum and / or the proximal side of the saw chain drive sprocket.

[0015] According to an embodiment, the electric motor may have: a rotor configured to rotate by a stator, the rotor having an external rotor diameter; and an output shaft drivably connected to a slip clutch, the output shaft having a shaft diameter, wherein the ratio between the rotor diameter and the shaft diameter is between 2.5 and 4.8. This range of ratios has been found suitable for achieving a proper balance between the weight and durability of the transmission. 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 between the rotor diameter and the clutch engagement surface diameter may be between 0.50 and 1.2. A typical suitable shaft diameter may be, for example, between 10 mm and 15 mm. According to an embodiment, the clutch drum as defined above may be rotatably arranged on the output shaft via a bearing, such as a needle roller bearing. The shaft diameter may be the diameter of the shaft at its axial position relative to the bearing. Optionally, the output shaft may be provided with a lubrication channel extending from the needle roller bearing to a lubricant inlet in the end face of the output shaft.

[0016] According to embodiments, the slipper clutch can be electromagnetically actuated based on a clutch control signal. For example, the slipper clutch can be actuated by an excitation coil that axially moves at least one of the driving and driven members, i.e., along the rotational axis of the slipper clutch, to engage the other of the driving and driven members. Optionally, the chainsaw may include a sensor configured to detect the engagement state of the slipper clutch, i.e., whether the slipper clutch is engaged or disengaged, and / or whether the slipper clutch is in a slip-allowed state or a locked state. This state can 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 slipper clutch based on that rotational speed. This arrangement can, for example, provide increased degrees of freedom in selecting or adjusting the clutch engagement speed. According to some embodiments, the chainsaw may be equipped with a user interface that allows the user to set the clutch engagement speed.

[0017] According to one embodiment, the handheld battery-powered chainsaw may further include a mechanical braking device movable between a braking position and a release position. In the braking position, the mechanical braking device is configured to engage with a transmission to brake the rotation of the driven member; in the release position, the driven member rotates freely. According to another embodiment, the mechanical braking device is configured to engage with the transmission on the driven member side of a slip clutch. Therefore, the mechanical braking device can stop the chain rotation regardless of the engagement position of the slip clutch. Alternatively or additionally, according to another embodiment, the mechanical brake may include a brake drum and a brake band configured to be tensioned around the brake drum. The brake drum may be separate from any clutch drum, as appropriate; or, the brake band may be provided to engage with the radially outer surface of a centrifugal clutch drum, so that the centrifugal clutch drum can also function as a brake drum.

[0018] According to one embodiment, the handheld battery-powered chainsaw may further include a rear handle equipped with a finger-operated trigger for operating the motor, wherein a mechanical braking device is configured to operate independently of the trigger's position. Therefore, safe operation is achieved in all situations. According to another embodiment, the mechanical braking device may be configured to remain in the released position when the trigger is released. Therefore, when the trigger is released, the inertia of the motor and transmission can be at least partially maintained, which reduces power consumption. This is, of course, particularly advantageous for battery-powered chainsaws.

[0019] According to one embodiment, the driven member may include a clutch drum, and the mechanical braking device may include a brake band configured to apply a clamping force on the radially outer surface of the clutch drum in response to actuation of a brake actuator. The brake actuator may include a recoil brake lever configured as a handguard in front of the chainsaw handle.

[0020] According to one embodiment, the mechanical braking device may include a brake drum axially separated from the slipper clutch, and a brake band configured to apply a clamping force on the radially outer surface of the brake drum in response to actuation of the brake actuator. According to another embodiment, the brake drum may be positioned proximal to the clutch, resulting in a particularly compact arrangement. Furthermore, the brake actuator may include a recoil brake lever configured as a handguard in front of the chainsaw handle.

[0021] According to one embodiment, the handheld battery-powered chainsaw may further include an electrically controlled brake, such as an electromagnetic brake and / or an inductive brake. Such a brake can help stop the saw chain. The electrically controlled brake can be selectively actuated by a controller, for example, in response to detecting that a trigger for operating the motor has been released by the operator. For example, the inductive brake can be implemented in the motor controller to selectively apply braking force to the motor rotor. According to an alternative embodiment of the inductive brake, the chainsaw can be configured to short-circuit the motor windings when the trigger is released by the operator.

[0022] According to one embodiment, the electric brake can be configured to apply braking force to the drive member side of the slipper clutch, i.e., to the electric motor, to the drive member, and / or to any element fixedly attached thereto. Such an electric brake can provide a particularly compact and lightweight arrangement. It can be advantageously combined with a mechanical brake for braking the driven member side of the slipper clutch.

[0023] According to an embodiment, the chainsaw can be configured to release the electrically controlled brake in response to a decrease in the motor speed below the electric brake release speed. Therefore, when the trigger is released, the angular momentum of the motor and drive member can be at least partially preserved, saving electrical energy and shortening the time required to accelerate the motor to the clutch engagement speed upon the next press of the trigger. Furthermore, if combined with a fan, cooling of the motor and / or any battery and / or controller is improved. Preferably, if combined with a slipper clutch actuated in response to changes in the rotational speed of the drive member 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.

[0024] According to one embodiment, the electric motor may include a rotor configured to rotate about the motor's rotational axis, and a drive member is rotatably locked to the rotor in a form-fit manner to prevent the drive member from rotating about the motor's rotational axis in two rotational directions. For example, the drive member may be keyed to the motor's output shaft, for example, via a spline, semi-circular key, or D-key engagement. According to another embodiment, the drive member may be axially held to the output shaft by, for example, a nut or screw, optionally combined with a washer. Form-fit rotational locking may be particularly advantageous when combined with electric braking of the motor, because braking or acceleration may additionally cause the drive member to rotate relative to the rotor, even if there is a strong frictional engagement therebetween.

[0025] According to one embodiment, the handheld battery-powered chainsaw may further include a cooling fan coupled to always operate with the drive member side of the slip clutch. Therefore, the cooling fan can be operated without operating the chainsaw chain. This allows for the cooling of any parts of the chainsaw that could benefit from cooling, such as the motor, controller, and / or battery, at any time. For example, the cooling fan may be operated to cool the chainsaw before use at high ambient temperatures or when the chainsaw has been stored in a warm environment. Furthermore, since the chainsaw typically operates intermittently at maximum power under normal use conditions, the cooling fan can cool the chainsaw during the intermittent periods. This allows for the design of chainsaws with higher peak output power without increasing the risk of overheating any part of the chainsaw or triggering any overheat protection mechanisms, depending on the circumstances. The cooling fan may be arranged in a housing shaped to direct airflow to the motor, controller, and / or battery. According to another embodiment, the cooling fan may be rigidly connected to the output shaft of the motor. The cooling fan may include a fan rotor provided with a set of blades configured to move cooling air. According to some embodiments, the cooling fan may be configured as an axial flow fan. According to other embodiments, the cooling fan can be configured as a centrifugal fan including an impeller arranged in a volute. The latter has the added advantage of being well-suited for achieving relatively higher cooling air pressures, which is beneficial for distributing cooling air to all relevant areas when components are densely assembled in a compact construction. The fan can be made of, for example, aluminum or plastic.

[0026] According to one embodiment, the slip clutch can be positioned on a first axial side of the motor, and the cooling fan can be positioned on a second axial side of the motor opposite to the first axial side. This arrangement allows the motor to be positioned towards the lateral center of the chainsaw, ensuring good balance and increased comfort. According to another embodiment, the motor can be housed within a motor housing, and the cooling fan can include a fan rotor with multiple blades, wherein the cooling fan has an outer diameter exceeding the diameter of the motor housing. Therefore, cooling of the slip clutch can be improved.

[0027] According to one embodiment, the handheld battery-powered chainsaw may further include a chainsaw oil pump, which is coupled to receive power from the driven member side of the slip clutch. Therefore, even when the motor is running, chainsaw oil will be supplied to the chainsaw only when the chainsaw is moving. This conserves chainsaw oil. According to another embodiment, the oil pump may be operated from 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 motor. According to another embodiment, the worm screw may be positioned between the motor and the slip clutch.

[0028] According to one embodiment, the handheld battery-powered chainsaw may further include a controller configured to operate a slip clutch between an engaged state and a disengaged state. In the engaged state, the slip clutch is configured to drive the saw chain, and in the disengaged state, the drive member is free to rotate without driving the saw chain. For example, the controller can operate the slip clutch in response to an operator input by running the motor at a speed above or below the clutch engagement speed.

[0029] According to one embodiment, the controller can be configured to maintain the operation of the electric motor even when the slipper clutch is disengaged. Therefore, any auxiliary components of the electric motor or transmission connected to the drive side of the slipper clutch, such as a fan, can be operated without operating the saw chain. Specifically, the controller can be configured to maintain the operation of the electric motor even when the slipper clutch is disengaged in response to the detection that a trigger for finger operation of the electric motor has been fully released. For example, the slipper clutch can be a centrifugal clutch, and the electric motor can be kept at an idle speed below the engagement speed of the centrifugal clutch. The idle speed can be a predetermined speed set in the controller. Exemplary suitable idle speeds can be between 2000 rpm and 6000 rpm, and more preferably between 3000 rpm and 5500 rpm. According to one embodiment, the controller can be configured to maintain the operation of the electric motor without engaging the slipper clutch for a predetermined time, which can typically be greater than two seconds, and more typically greater than ten seconds. Alternatively or additionally, the controller can be configured to maintain the operation of the electric motor until an external event is detected, such as the temperature of a part of the chainsaw dropping below a critical temperature, or the chainsaw's power switch being turned off. According to one implementation, the controller can be configured to automatically start the motor without engaging the slipper clutch when the chainsaw is turned on, for example via an on / off switch, or when the chainsaw detects that it has been lifted or gripped by the handle.

[0030] According to one embodiment, the controller can be configured to maintain the operation of the motor, thereby operating the chainsaw's cooling fan, based on a detected temperature exceeding a temperature limit, even when the slipper clutch is disengaged. According to another embodiment, the chainsaw may further include at least one temperature sensor, and the detected temperature can be a temperature detected by said at least one temperature sensor. For example, the at least one temperature sensor can detect the temperature of the motor, controller, and / or battery. Alternatively, the detected temperature can be the ambient temperature detected by a temperature sensor external to the chainsaw. The temperature limit can be fixed or dynamically set.

[0031] According to one embodiment, the handheld battery-powered chainsaw may further include a trigger that is movable between a depressed position and a released position, wherein a motor operates in response to the depressed position to move the saw chain, and the saw chain stops in response to the released position, wherein a controller is configured to enable the motor to operate when the trigger is in the released position.

[0032] According to one implementation, the controller can be configured such that when the trigger is in the released position, the motor can be operated based on the condition that the mechanical brake, configured as the braking driven member, is engaged. This arrangement increases the safety of the chainsaw by mitigating the consequences of any failure of the slipper clutch.

[0033] According to an implementation, the controller can be configured to detect excessive clutch slip, for example by detecting an extended operation below the slip limit speed above which the slip clutch is locked; and in response to detecting excessive clutch slip, to apply a change to the control signal for operating the motor. Excessive clutch slip, i.e., clutch slip that extends excessively over time, is an undesirable situation that generates heat and causes wear on the slip clutch and the motor. For example, the controller can be configured to determine that slip has occurred during a period exceeding a predetermined slip limit time. An exemplary suitable change to the control signal for operating the motor could be to automatically increase the torque, which could, for example, increase the speed of the slip clutch above the slip limit speed to set the saw chain into motion, or automatically reduce the speed of the motor to or below the clutch engagement speed to reduce wear and heat generation. Furthermore, changes in the control of the motor can also help to provide an audible or tactile warning to the chainsaw operator about excessive slip, allowing the operator to take corrective action by, for example, reducing the pressure of the saw chain applied to the material to be cut, or by releasing a trigger as defined above.

[0034] According to one embodiment, applying the change to the control signal used to operate the motor may include applying a pulse to the torque delivered by the motor and / or changing the speed of the motor. Thus, the user can be effectively notified, audibly or tactilely, in a highly intuitive manner that the motor is trying to exceed the slip torque of the slip clutch, and the user can take corrective action, for example, by reducing the saw chain pressure applied to the material to be cut. Furthermore, the pulsed torque or varying speed can facilitate setting a saw chain that may have jammed back into motion. For example, the torque can be pulsed by applying a pulse to the drive current to the motor, or by applying an intermittent phase shift of the drive current to the 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, to 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, to provide tactile feedback to the operator. The pulse frequency may be fixed or varied within a pulse sequence. The pulse can be configured as a square wave pulse, enabling the emission of audible overtones over a wide frequency range, thus making the pulse audible even in complex background noise environments. Similarly, a suitable, exemplary speed variation can be periodic, having a frequency, for example, between 0.2 Hz and 10 Hz. A suitable, exemplary amplitude of the rotational speed variation can be at least 10 rpm, and more typically, between 50 rpm and 1000 rpm.

[0035] According to one embodiment, the controller can be configured to apply pulses to the torque delivered by the electric motor for no more than a limit time or a limit number of pulses, and then reduce the speed of the electric motor below the clutch engagement speed. This allows the chainsaw to cool down while preventing further attempts to exceed the slip limit speed. This allows for higher output power from the electric motor without increasing the risk of overheating or damage to any components. Depending on the specific circumstances, the limit time or the number of pulses can be predetermined. According to one embodiment, the controller can be configured to apply pulses to the torque for less than 30 seconds, and more preferably less than 10 seconds, before reducing the speed of the electric motor below the clutch engagement speed.

[0036] According to one embodiment, a handheld battery-powered chainsaw may include a trigger movable between a depressed position and a released position, activating a motor to move the saw chain in response to the depressed position and stopping the saw chain in response to the released position. The controller is configured to prevent any speed increase to the slip limit speed after the motor speed has been reduced below the clutch engagement speed, until the trigger has been released and subsequently pressed again. This configuration allows the operator to easily restart the chain using only the trigger.

[0037] According to one implementation, the motor can be an outrunner comprising a rotating fixed stator with stator windings, the stator being radially surrounded by a rotor with a set of permanent magnets. Compared to an inner rotor, an outer rotor typically cools itself better, reducing the need for a separate fan impeller. Furthermore, outer rotors are generally less expensive than inner rotors, but have a higher moment of inertia, resulting in slower acceleration. While high moment of inertia is a disadvantage at initial acceleration, it can be beneficial at higher speeds when the saw is engaged with the material to be cut. Engagement with a clutch allows for rapid acceleration of the outer rotor upon clutch disengagement, thus providing the benefit of increased moment of inertia at higher speeds without the disadvantage of excessively slow acceleration at lower speeds.

[0038] According to the implementation method, the electric motor can be a vector-controlled permanent magnet motor. This type of motor offers good controllability and is well-suited for the specific operating method defined herein.

[0039] According to the implementation, the controller can be configured to detect motor overload and, in response, maintain or increase the motor torque. Motor overload can be detected by detecting a drop in motor speed below a certain position of the trigger or a desired speed for a given motor torque. Without a slipper clutch, if motor overload is detected, for example, by detecting a drop in speed below the limit speed, it may be advantageous to quickly and sufficiently reduce the motor torque, for example, by reducing the current supplied to the motor, to prevent overheating. However, when combined with a slipper clutch, it may be advantageous to maintain a high motor torque even when an overload is detected, since the slipper clutch will prevent the motor from stopping completely anyway. Maintaining or increasing torque in the speed range of the slipper limit speed facilitates restarting the saw chain that has become jammed due to, for example, lateral compression or excessive pressure applied by the operator. Furthermore, if combined with a fan rotated by the motor, the fan will maintain cooling airflow to the motor, which improves the preconditions for maintaining high torque.

[0040] According to one embodiment, a handheld battery-powered chainsaw may include a chainsaw body; an elongated guide rod for guiding the saw chain, wherein the extension direction of the guide rod defines a longitudinal axis, the guide rod extending forward along the longitudinal axis from the front end of the chainsaw body, wherein the guide rod extends in a plane; a front handle; and a rear handle, wherein the bottom surface of the rear handle is provided with a trigger that allows the operator to operate the motor, the plane being parallel to the guide rod plane and including the last point intersecting the vertex of the front handle at the intersection point, the distance between the intersection point and the last point of the trigger exceeding 270 mm. Due to the slip clutch, a large distance can be provided between the front and rear handles without causing substantial problems due to the operator pressing the chain too hard against the material to be cut. Therefore, the stability and controllability of the chainsaw can be increased. According to another embodiment, the distance between the intersection point and the last point of the trigger can exceed 300 mm, 320 mm, 340 mm, or even 360 mm.

[0041] According to one implementation, the chainsaw can be configured to run the motor up to maximum output power, wherein the ratio between the distance from the trigger's intersection point to the final point and the maximum output power exceeds 0.11 mm / W. The clutch allows for engagement of the relatively long distance between the rear and front handles with a moderately applied power motor without the risk of the motor stalling.

[0042] According to one embodiment, the chainsaw can be configured to operate a motor to generate motor torque, wherein the motor torque reaches a sliding torque at the sliding limit speed defined above, and wherein the ratio between the distance from the intersection point to the last point of the trigger and the sliding torque exceeds 90 mm / Nm. A clutch allows for the engagement of a relatively long distance between the rear and front handles with a suitable motor torque without the risk of the motor stopping.

[0043] According to the second aspect, a handheld battery-powered chainsaw solves or at least mitigates some or all of the aforementioned problems. The chainsaw includes: an electric motor; a transmission coupled to the electric motor, wherein the electric motor is configured to drive a saw chain via the transmission; a controller for operating the electric motor; and a trigger operably coupled to the controller, the trigger being movable between a depressed position and a released position. In response to the depressed position, the controller is configured to operate the electric motor to drive the saw chain, and in response to the released position, the controller is configured to stop driving the saw chain. The transmission includes a clutch comprising a drive member configured to receive rotational power from the electric motor and a driven member configured to transmit the rotational power to the saw chain. The clutch is movable between an engaged state and a disengaged state. In the engaged state, the clutch engages the electric motor with the saw chain, and in the disengaged state, the clutch disengages the electric motor from the saw chain, allowing the drive member to rotate freely without driving the saw chain. The controller is configured to automatically maintain the operation of the electric motor in an idle mode when the trigger is in the released position, wherein the clutch is in the disengaged state. The idle mode maintains the rotational inertia of the electric motor and the clutch drive side, allowing the saw chain to accelerate more quickly once it begins to move. The clutch can be, for example, a slipper clutch or a claw clutch, which can be configured according to any of the embodiments defined below or above. According to an embodiment, the clutch can be configured to switch between an engaged and disengaged state based on the rotational speed of the electric motor, and the idle mode can be maintained by operating the electric motor at an idle speed lower than the clutch engagement speed. The chainsaw according to the second aspect can be combined with various embodiments of the chainsaw according to the first aspect as defined above.

[0044] According to one embodiment, the clutch can be a centrifugal clutch, and the controller can be configured to automatically maintain the motor in idle mode at an idle speed lower than the engagement speed of the centrifugal clutch. According to another embodiment, the controller can be configured to automatically maintain the motor in idle mode at an idle speed more than 200 rpm lower than the engagement speed of the centrifugal clutch, and more preferably at an idle speed more than 500 rpm lower than the engagement speed of the centrifugal clutch. Alternatively or additionally, the controller can be configured to automatically maintain the motor in idle mode at an idle speed less than 3000 rpm lower than the engagement speed of the centrifugal clutch, and more preferably at an idle speed less than 1500 rpm lower than the engagement speed of the centrifugal clutch. This is particularly useful when combined with a fan operating in idle mode.

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

[0046] According to one embodiment, the handheld battery-powered chainsaw may further include a cooling fan, which is coupled to always operate together with the drive component side of the clutch.

[0047] According to a third aspect, a handheld, battery-powered chainsaw solves or at least alleviates some or all of the aforementioned problems, comprising: an electric motor; a transmission coupled to the electric motor, wherein the electric motor is configured to drive the saw chain via the transmission; 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. When using a chainsaw to cut logs, especially firewood, the user typically applies full throttle before starting to cut. Therefore, the additional rotational inertia of the flywheel is a significant improvement. For example, the typical drop in chain speed upon contact with the wood is reduced, and a complete cut becomes easier. Furthermore, for forests, there is a great need to quickly cut branches, for example, to be pruned, as this reduces the tendency of branches to swing downwards before they are completely cut. Results of experiments performed have shown that the additional rotational inertia of the flywheel increases the cutting speed when pruning. According to an embodiment, the flywheel may be carried by the output shaft of the drive electric motor and optionally rigidly connected to the output shaft. According to an embodiment, the flywheel may have a weight between 80g and 250g. It can typically have an outer diameter between 70mm and 130mm. An exemplary suitable moment of inertia range for a flywheel can be 1.2*10. -4 kgm 2 and 3.5*10 -4 kgm 2 Between. Alternatively or additionally, at least 80%, more preferably at least 85%, of the total weight of the flywheel may be located at a radial position relative to the flywheel axis of rotation exceeding 50% of the total radius of the flywheel. This weight distribution provides a beneficial ratio between self-weight and rotational inertia. The chainsaw according to the third aspect can 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 in any of the embodiments above. According to another embodiment, the clutch may be positioned on a first axial side of the motor, and the flywheel may be positioned on a second axial side of the motor, opposite to the first axial side. The flywheel may optionally be provided with blades for operation as a fan. A large portion of the flywheel's weight may be provided by a metal (e.g., steel) inertia ring. The inertia ring may extend radially to at least 90% of the total radius of the flywheel.

[0048] According to the fourth aspect, a handheld, battery-powered chainsaw solves or at least mitigates some or all of the aforementioned problems, the chainsaw comprising: an electric motor including a rotor configured to rotate about a rotational axis of the motor; and a plurality of components driven by the motor to rotate about the rotational axis of the motor, wherein the total moment of inertia of the rotor and the plurality of components exceeds 1.5 × 10⁻⁶.-4 kgm 2 According to another embodiment, the total moment of inertia of the plurality of components can exceed 1.9 * 10^9. -4 kgm 2 Furthermore, according to a further embodiment, the total moment of inertia of the plurality of components can exceed 2.3 * 10⁻⁶. -4 kgm 2 It can exceed 2.8*10 -4 kgm 2 Or even more than 3.5*10 -4 kgm 2 These multiple components may include all or a subset of the components of the transmission, flywheel, and fan as defined above.

[0049] According to the fifth aspect, a handheld, battery-powered chainsaw solves or at least mitigates some or all of the aforementioned problems, the chainsaw comprising: an electric motor including a rotor configured to rotate about a rotational axis of the motor; and a plurality of components configured to be driven by the motor to rotate about a rotational axis of the motor, wherein the ratio J / M between the total moment of inertia J of the rotor and all components configured to be driven by the motor to rotate about a rotational axis of the motor and the total mass M of the rotor and all components configured to be driven by the motor to rotate about a rotational axis of the motor exceeds 3.6 m. 2 According to another embodiment, the ratio can exceed 4.1m. 2 It can exceed 4.6m 2 It can exceed 5.1m 2 It can exceed 5.6m 2 Or even more than 6.1m 2 Furthermore, the total moment of inertia of the rotor and all components configured to rotate around the motor's axis of rotation can exceed 1.5 x 10⁻⁶. -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 As specified above.

[0050] According to the sixth aspect, a method for controlling an electric motor to selectively drive the saw chain in a chainsaw solves or at least mitigates some or all of the aforementioned problems, the chainsaw including a trigger for initiating rotation of the saw chain, the method comprising: operating the electric motor before detecting the depressurization of the trigger; and setting the saw chain to motion in response to detecting the depressurization of the trigger. Thus, the inertia of the electric motor and any transmission mechanism will contribute to the acceleration of the saw chain, which can produce a faster response of the chainsaw to the operation of the trigger. The depressurization of the trigger can be detected relative to a fully released position. This method can be combined with any of the chainsaws defined above. According to one embodiment, the saw chain can be moved by engaging the electric motor with the saw chain via a clutch. Alternatively, the electric motor can be connected to the saw chain via a torque limiter, and the saw chain can be moved by releasing a mechanical chain brake. The method may further include: using the electric motor to drive a cooling fan before detecting said depressurization of the trigger.

[0051] According to the embodiments, mechanically engaging the electric motor with the saw chain may include increasing the rotational speed of the electric motor to a speed greater than the clutch engagement speed.

[0052] According to the seventh aspect, a method for selectively driving a saw chain in a chainsaw by controlling an electric motor addresses or at least mitigates some or all of the aforementioned problems. The chainsaw includes a trigger for initiating rotation of the saw chain. The method includes: operating the saw chain in response to detecting the pressing of the trigger; stopping the operation of the saw chain in response to detecting the release of the trigger; and maintaining the operation of the electric motor after stopping the operation of the saw chain. Therefore, inertia can be stored / retained until the next operation of the saw chain, which saves energy. Alternatively or additionally, the electric motor can maintain the operation of other functions, such as the operation of a fan. The operation of the electric motor can be maintained without restarting the operation, at least until the next pressing of the trigger. Stopping the operation of the saw chain can include mechanically disengaging the electric motor from the saw chain. Alternatively, the electric motor can be connected to the saw chain via a torque limiter and the operation of the saw chain can 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 include: operating the electric motor after detecting the complete release of the trigger. The method can be combined with any of the methods or chainsaws defined above.

[0053] According to one embodiment, mechanically disengaging the motor from the saw chain may include reducing the motor speed to below the clutch engagement speed.

[0054] According to the eighth aspect, a method for controlling an electric motor to selectively drive the saw chain in a chainsaw solves or at least mitigates some or all of the aforementioned problems, the method comprising: operating the electric motor at a first rotational speed in response to detecting the depressing of a trigger; and operating the electric motor at a second rotational speed in response to detecting the release of the trigger. This method can be combined with any of the methods or chainsaws defined above, and can be implemented, for example, in the controller of the chainsaw. Preferably, the saw chain is coupled to be operated by the electric motor at the first rotational speed and disengaged from the electric motor operating at the second rotational speed. According to an embodiment, the chainsaw may include a fan coupled to be rotated by the electric motor when operating at the second rotational speed. Alternatively or additionally, the chainsaw may include a chain oil pump coupled to be operated by the electric motor at the first rotational speed and disengaged from the electric motor operating at the second rotational speed. According to an embodiment, the second rotational speed may be lower than the clutch engagement speed.

[0055] According to the ninth aspect, a method for controlling an electric motor to selectively drive a saw chain in a chainsaw including a clutch solves or at least mitigates some or all of the aforementioned problems. The method includes: determining the state of the clutch; and, based on the determined clutch state, adjusting the torque or speed of the electric motor; and / or generating an alarm to the operator of the chainsaw. This method can be combined with any of the methods or chainsaws defined above. Exemplary clutch states can be a disengaged state, a slippery state, a slippery state indicating actual slippage of the clutch, and / or a locked state. The method may include determining whether a single state in the exemplary states has occurred, may have occurred, or may be about to occur. For example, the method may include determining a period of time during which the clutch has been in a slippery state for a limit time, which may be predetermined or dynamically set. An alarm to the operator can be generated, for example, by illuminating a light, emitting an alarm sound, or operating the electric motor according to a predetermined pattern. According to an embodiment, determining the state may include determining the speed of the electric motor. For speed-actuated clutches, the clutch state can be directly derived from the speed.

[0056] According to the implementation, determining the state of the clutch may include determining the current rotational speed. For example, the torque or rotational speed may be adjusted in response to the determination that the chainsaw has been operating at a slip limit speed as defined above for a period of time exceeding the limit, or at a permissible slip speed between the clutch engagement speed and the slip limit speed. Alternatively, the torque or rotational speed may be adjusted immediately in response to the determination that operation is in a slipping state. The torque may be adjusted by controlling the current supplied to the motor.

[0057] According to the implementation, the clutch state can be a slippery state, and adjusting the torque or speed of the motor can include reducing the speed below the clutch engagement speed and / or reducing the torque of the motor. The reduction in torque or speed can be achieved by exceeding any operator input from, for example, a trigger. Therefore, prolonged or excessively difficult operation of the chainsaw at the clutch engagement speed can be avoided, which reduces heat generation and increases the lifespan of the clutch and any bearings.

[0058] According to some embodiments, the clutch state can be a slippery state, wherein adjusting the torque or speed of the motor includes increasing the torque of the motor. The torque can be temporarily increased above the continuous operating torque without the risk of overheating the motor. This is beneficial for moving a stopped chain, for example, if the saw chain is pressed forcefully against the material to be cut or squeezed into the saw kerf. According to some embodiments, the speed and / or torque can be initially reduced and then increased, or vice versa.

[0059] According to the tenth aspect, a method for controlling an electric motor to selectively drive the saw chain in a chainsaw solves or at least mitigates some or all of the aforementioned problems, the method comprising: determining a current rotational speed; and, based on the determination, actuating an electromechanical clutch, such as an electromagnetic clutch. The electromechanical clutch can engage when the speed of the electric motor exceeds the clutch engagement speed. Similarly, the electromechanical clutch can disengage when the speed of the electric motor drops below the clutch disengagement speed. The engagement speed can be the same as the disengagement speed, or they can be different. Furthermore, this method can be combined with the method or chainsaw defined above.

[0060] According to an embodiment, the method may further include receiving clutch engagement speed settings and / or clutch disengagement speed settings from a user interface. Thus, an operator or maintenance technician can set desired engagement or disengagement speeds to suit different applications. For example, in applications where there is a high risk of saw chain jamming, a high clutch engagement speed may be desirable, thus benefiting from the high angular momentum of the motor that moves a jammed chain.

[0061] According to the eleventh aspect, a data processing device comprising at least one processor and a memory solves or at least mitigates some or all of the aforementioned problems, the data processing device being configured to perform any of the methods defined above. The data processing device may be arranged in a handheld chainsaw, such as the handheld chainsaw defined above. The data processing device may be implemented as a microcontroller.

[0062] According to the twelfth aspect, a computer program product including instructions solves or at least mitigates some or all of the aforementioned problems, wherein when the program is implemented on a processor, the instructions perform any of the methods defined above.

[0063] According to aspect thirteen, a computer-readable storage medium having a computer program product as defined above stored thereon solves or at least mitigates some or all of the aforementioned problems.

[0064] It should be noted that embodiments of the present invention can be implemented through all possible combinations of the features described in the claims. Furthermore, it will be understood that the various embodiments described for the apparatus can be combined with methods, and vice versa. Attached Figure Description

[0065] The above and additional objects, features, and advantages of the invention will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the invention with reference to the accompanying drawings, wherein like reference numerals will be used for similar elements, in which:

[0066] Figure 1A This is a side view of the handheld battery-powered chainsaw according to the first embodiment;

[0067] Figure 1B It is as seen from above. Figure 1A A plan view of the chainsaw;

[0068] Figure 2 yes Figure 1A and Figure 1B A perspective view of a chainsaw, with the sprocket cover removed to expose the drive mechanism;

[0069] Figure 3A yes Figure 2 A perspective view of the motor of a chainsaw, which is connected to... Figure 2 The fan and transmission mechanism;

[0070] Figure 3B It corresponds to Figure 3A A plan view of the view;

[0071] Figure 4 yes Figure 1A An enlarged view of the interface between the saw chain, the saw chain drive sprocket, and the guide bar of a chainsaw, which essentially corresponds to the view along... Figure 3B The cross section intercepted by line IV-IV;

[0072] Figure 5 It is a schematic block diagram showing Figure 1A The functional blocks of the motor and controller of the chainsaw;

[0073] Figure 6A yes Figure 3A and Figure 3B Exploded perspective view of the electric motor, fan, and transmission mechanism;

[0074] Figure 6B yes Figure 3A and Figure 3B A sectional view of the electric motor, fan, and transmission, wherein the section is along... Figure 3B The line VI-VI is cut off;

[0075] Figure 7A yes Figure 6A and Figure 6B The view of the electric motor, fan, and transmission as seen from a first-person perspective;

[0076] Figure 7B yes Figure 7A The view of the electric motor, fan, and transmission as seen from a second-person perspective;

[0077] Figure 7C yes Figure 7A and Figure 7B The electric motor, fan, and transmission device are along Figure 7A A plan view showing axis A as indicated in the center;

[0078] Figure 7D yes Figures 7A to 7C A cross-sectional view of the electric motor, fan, and transmission device, the section being along... Figure 7C The line DD was cut off;

[0079] Figure 8A It is a schematic illustration of... Figure 4 The saw chain was not blocked Figure 3A The first graph shows the torque and speed of the electric motor and transmission as a function of the motor's speed.

[0080] Figure 8B It is schematically shown in Figure 4 When the saw chain is blocked Figure 3A A graph showing the torque and speed of the electric motor and transmission as a function of the motor's speed;

[0081] Figure 9 This is a perspective view of a chainsaw according to the second embodiment, wherein the sprocket cover has been removed to expose the transmission device according to the second embodiment.

[0082] Figure 10 Is with Figure 3A The corresponding view Figure 9 A plan view of the chainsaw's motor, which is connected to... Figure 9 The fan and transmission mechanism;

[0083] Figure 11 yes Figure 10 A perspective view of the transmission device;

[0084] Figure 12 This is a schematic cross-sectional view of the electric motor and transmission device according to the third embodiment;

[0085] Figure 13 This is a schematic diagram of the transmission device according to the fourth embodiment;

[0086] Figure 14 This is a schematic diagram of the transmission device according to the fifth embodiment;

[0087] Figure 15 It shows the operation Figure 1A and Figure 9 A flowchart of the first method for chainsaws;

[0088] Figure 16 It shows the operation Figure 1A and Figure 9 The flowchart of the second method of the chainsaw;

[0089] Figure 17 Is with Figure 3A The plan view corresponding to the view is a view of the electric motor that drives the transmission device, fan and flywheel according to the first embodiment.

[0090] Figure 18A Is with Figure 3A The plan view corresponding to the view is the electric motor and transmission device, and the combined fan and flywheel according to the first embodiment.

[0091] Figure 18B yes Figure 18A The combination of fan and flywheel along Figure 18A A plan view from axis A; and

[0092] Figure 19 It is a perspective view of the data carrier.

[0093] All accompanying drawings are schematic and not necessarily drawn to scale, and generally only show the parts necessary to illustrate the implementation, where other parts may be omitted. Detailed Implementation

[0094] Figure 1AA handheld, battery-powered chainsaw 10 is shown. The chainsaw 10 includes a chainsaw body 12 with a pair of handles 14a, 14b, which an operator (not shown) can grip and operate the chainsaw 10. The handles include a front handle 14a typically used for left-hand grip and a rear handle 14b typically used for right-hand grip. A cutting assembly including a saw chain 16 and an elongated guide bar 18 guiding the saw chain 16 in an elongated loop extends from the front end of the chainsaw body 12 along the longitudinal axis X of the chainsaw 10, defined by the longitudinal axis of the guide bar 18. The vertical axis Y of the chainsaw is perpendicular to the longitudinal axis X and parallel to the plane of extension of the guide bar 18. The chainsaw 10 further includes a removable battery 20 in a battery compartment 20A, and a motor 22 (in...) Figure 1A (Illustrated only by a dashed circle in the middle), and a finger-operated trigger 24, which allows the operator to selectively move the saw chain 16 using the motor 22. The last point 24a of the trigger 24 along the longitudinal axis X is also indicated in Figure 1. The chainsaw further includes a controller 23 (in Figure 1A (Illustrated schematically by a dashed rectangle only), the configuration is based on input from trigger 24 to control motor 22. Trigger 24 extends downward from the bottom surface of rear handle 14b and is movable between a depressed position (not shown) and a released position (shown). In response to the depressed position, motor 22 operates to move saw chain 16, and in response to the released position, saw chain 16 stops. Handguard 25 in front of front handle 14a is operably connected to a mechanical brake for stopping saw chain 16 in case of kickback. The mechanical brake is a safety feature that operates independently of the position of trigger 24.

[0095] Figure 1B The chainsaw 10 is shown as viewed from above. A plane P parallel to the plane of the guide bar 18 includes the last point 24a of the trigger 24. Plane P intersects the uppermost vertex B of the front handle 14a, which is the uppermost point relative to the vertical Y direction of the chainsaw 10. (Return to reference) Figure 1A The distance between intersection point B and the last point 24a of the trigger is approximately 300mm.

[0096] Figure 2 Shown without saw chain 16 ( Figure 1A The chainsaw 10, and wherein the sprocket cover 26 ( Figure 1A The guide rod 18 is removed to expose its attachment to the chainsaw body 12, and the rotational power is transferred from the motor 22. Figure 1A ) passed to saw chain 16 ( Figure 1A ) transmission device 28.

[0097] Figure 3A and Figure 3BThe electric motor 22 and the transmission 28 are shown in more detail. In the embodiment of the centrifugal clutch 34, the transmission 28 specifically includes: an output shaft 30 of the electric motor 22, configured to rotate about the motor's rotation axis A; and a saw chain sprocket 32 ​​(…). Figure 3B The centrifugal clutch 34 includes a drive member 36 that rotates with the electric motor 22 and receives rotational power from the electric motor via an output shaft 30; and a driven member 38 that rotates with the saw chain sprocket 32 ​​and transmits rotational power to the saw chain sprocket. (The last part, "can be omitted," appears to be a fragment and doesn't need a direct translation.) Figure 3B As can be clearly seen, the drive member 36, the driven member 38, and the saw chain sprocket 32 ​​are all configured to rotate concentrically around the rotation axis A of the motor. As can be clearly seen from the construction of the transmission device 28, the transmission device 28 provides a 1:1 transmission ratio between the motor 22 and the saw chain sprocket 32.

[0098] The transmission device 28 further includes a brake drum 40a, configured to cooperate with a brake band 40b operated by the hand guard device 25 and a worm 42a for driving a worm gear drive (not shown) to drive the saw chain oil pump. Figure 3A In the view, the brake band 40b is shown schematically only at the height of the dashed line. Both the worm gear 42a and the brake drum 40a are rotatably fixed to the saw chain sprocket 32 ​​so as to rotate together with the driven member 38 of the centrifugal clutch 34. Clearly, both the worm gear 42a and the brake drum 40a are height-optional; saw chain oil can be pumped by any other suitable means if desired, and the brake band 40b can alternatively engage with the radially outer surface of the driven member 38 of the centrifugal clutch 34, if applicable.

[0099] like Figure 3B As shown, the centrifugal clutch 34 has a proximal side 34a facing the motor 22 and a distal side 34b away from the motor 22, and the saw chain drive sprocket 32 ​​is rigidly connected to the driven member 38 of the centrifugal clutch 34 on the proximal side 34a. This arrangement positions the saw chain drive sprocket 32 ​​relatively close to the transverse center of the chainsaw 10 defined by the plane P. Figure 1B ).

[0100] The transmission device 28 is positioned relative to the rotation axis A of the motor 22 on the first axial side 44a of the motor 22. Figure 3B On the second axial side 44b of the motor 22. Cooling fan 46 is located on the second axial side 44b of the motor 22. Figure 3BThe chain saw body 12 is rigidly connected to the output shaft 30, opposite the first axial side 44a. Therefore, the cooling fan 46 is coupled to always operate together with the drive member side of the motor 22 and the centrifugal clutch 34. The cooling fan 46 is configured as an axial flow fan and includes a fan rotor 48 with a set of blades 50 configured to blow cooling air across the motor 22 to cool it. (Internal structure of the chainsaw body 12) Figure 1A A fan housing (not shown) is defined, the shape of which is designed to direct airflow to the motor 22, controller 23, and / or battery 20. The cooling fan 46 is preferably made of a lightweight material, such as plastic.

[0101] Figure 4 In the Figure 3B The cross-section indicated by line IV-IV schematically shows the saw chain sprocket 32, a short section of the saw chain 16, and the proximal end of the guide rod 18. The saw chain sprocket 32 ​​is powered by an electric motor 22 ( Figure 1A ) via transmission device 28 ( Figure 3A and Figure 3B The saw chain 16 rotates and engages dynamically with the saw chain 16 to move along the guide bar 18. As is known per se, the saw chain 16 includes a drive link 16a that engages with the drive teeth 32a of the saw chain sprocket 32, a cutting link 16b, and a tie strap 16c that holds the drive link 16a together.

[0102] Figure 5The functional elements of an electric motor 22 and the functional blocks of a controller 23 for controlling the electric motor 22 are schematically shown. The electric motor 22 includes a stator 52 and a rotor 54 concentric with the stator 52 radially inward. Alternatively, the motor may be of a different type, such as an external rotor (not shown). In the illustrated embodiment, the electric motor 22 is a brushless direct current (BLDC) motor or a permanent magnet synchronous motor (PMSM) with a permanent magnet rotor. The stator 52 is typically a multiphase stator, typically having three-phase windings 52a, 52b, and 52c. Windings 52a-52c are controlled by an inverter 23a using a field-oriented control (FOC) scheme. The inverter 23a receives power from a battery 20 and supplies power to the motor windings 52a-52c according to a pulse width modulation scheme. A converter may be included in the inverter 23a to increase the voltage applied to the windings 52a-52c. To use FOC, the corresponding currents applied to windings 52a-52c can be measured, and the converter can convert those currents into DC and quadrature currents, respectively, related to the instantaneous magnetic field of rotor 54, via Clark / Parker conversion unit 23b. These converted currents are supplied to control logic 23c, and the sensor output from an optional angular position sensor 56, which estimates the orientation of rotor 54, can also be supplied to control logic 23c. Control logic 23c typically performs control operations, such as based on a PI (proportional, integral) control scheme, to minimize parallel current components that do not contribute to rotor torque, and to obtain a desired vertical component based on the input desired torque value, which generates torque, based on the input desired torque value from trigger 24 (…). Figure 1A The input is obtained from the inverter. Control logic 23c generates DC and quadrature voltages in this manner, and uses inverse Clark / Parker and space vector modulation (SVM) modulation unit 23d to convert these voltages into the desired inverter duty cycle values ​​to control the inverter to generate the corresponding winding voltages. Controller 23 thus enables precise control of the output torque of motor 22 independently of the speed of motor 22. Controller 23 can be configured to allow the motor to operate at the output shaft 30 (… Figure 3AThe maximum torque Tm is provided at the output shaft 30, for example, between 2 Nm and 4.5 Nm at speeds of approximately 4000-7000 rpm. Furthermore, the controller 23 can be configured to enable the motor 22 to provide an exemplary maximum output power E between 1.8 kW and 4.5 kW at the output shaft 30. A temperature sensor 57 transmits the temperature of the motor 22 to the controller 23, allowing the controller 23 to detect any risk of overheating in the motor 22. The controller 23 also includes a corresponding temperature sensor 23g, which enables the detection of overheating in the controller 23 itself. The controller 23 also includes a sensing brake 23e, controlled by control logic 23c to selectively apply braking force to the motor rotor, for example, when the trigger 24 is released by the operator. The sensing brake 23e can apply braking force to the rotor 54 by, for example, reversing the polarity of the magnetic field generated by the stator windings 52a-52c or by short-circuiting the motor windings 52a-52c. The controller 23 further includes a wireless connection interface 23f for communicating with an external user interface 27 (e.g., a smartphone). Therefore, the controller 23 can receive settings and / or commands from an operator (not shown) via the external user interface, and / or send alarms to the operator via the external user interface 27. Obviously, the user interface can also be directly mounted on the chainsaw body 12.

[0103] Figure 6A It is an exploded perspective view of the electric motor 22, the fan 46, and the transmission device 28, while Figure 6BThe same items are shown in a cross-section taken along the rotation axis A of the motor. The output shaft 30 has a first axial end 30a, which is provided with a first end connection interface 31a for engaging with a drive member 36 of a centrifugal clutch 34. The first end connection interface 31a is configured as a keyed interface (not shown) to rotatably lock the output shaft 30 to the drive member 36; for example, the first end connection interface 31a may be configured as a D-key. The drive member 36 may be axially held in place by, for example, a screw (not shown) engaging 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 a cooling fan 46. The second end connection interface 31b is also configured as a keyed interface to rotatably lock the output shaft 30 to the cooling fan 46. The cooling fan 46 may be axially held in place by, for example, a screw (not shown) engaging a threaded hole in the second axial end 30b of the output shaft 30. Near the second end connection interface 31b, the output shaft 30 has an intermediate connection interface 31c for engaging with the rotor 54. The intermediate connection interface 31c is also configured as a keyed interface to rotatably lock the output shaft 30 to the rotor 54; in the illustrated embodiment, the keyed interface is defined by a spline. Between the intermediate connection interface 31c and the first end connection interface 31a, the output shaft 30 has a cylindrical segment 31d configured to define a bearing surface to radially support a bearing 58 configured as, for example, a needle roller bearing. Although shown as separate components for clarity, the saw chain sprocket 32 ​​can be welded to the driven member 38 of the clutch 34. When assembled, the worm gear 42a, clutch drum 40, and saw chain sprocket 32 ​​are in a forward-biased configuration. Figure 6B The corresponding shapes shown in the view are obviously inserted into each other axially and keyed to each other in a rotationally interlocked manner. Thus, the driven members 38 of the worm 42a, clutch drum 40, saw chain sprocket 32 ​​and centrifugal clutch 34 define a rotational rigidity unit 60, which is radially supported on the bearing 58 in a manner that allows it to rotate relative to the output shaft 30.

[0104] When in the assembled state, the stator 52 is housed in the motor housing 62a covered by the housing cover 62b, and the output shaft 30 is journal-supported in bearings 64a and 64b arranged in the motor housing 62a and housing cover 62b, respectively. Figure 6A The view also clearly shows the permanent magnets 54a distributed around the periphery of the rotor 54, and the windings 52a of the stator 52. (As shown...) Figure 6B As shown, the output shaft 30 has a lubrication channel 66 between the first axial end 30a and the cylindrical section 31d to lubricate the bearing 58.

[0105] Figures 7A to 7DThe transmission 28 is shown in more detail. The driven member 38 of the centrifugal clutch 34 is configured as a clutch drum having a cylindrical inner clutch engagement surface 38a. It will be understood that other shapes of the clutch engagement surface 38a, such as a truncated cone, may also be suitable for the centrifugal clutch.

[0106] The drive member 36 includes a pair of friction pads 68a, 68b held together by a pair of helical springs 70a, 70b. The friction pads 68a, 68b are axially held in place by friction pad guides 72 so as to be radially movable relative to the axis of rotation A. The friction pad guides are attached to the output shaft 30 in a rotationally fixed manner. In response to rotation of the drive member 36, the friction pads 68a, 68b overcome the bias of the helical springs and are radially pressed outward in the radial engagement direction toward the clutch engagement surface 38a of the clutch drum 38 by the centrifugal effect of their mass. Therefore, the centrifugal clutch 34 is inertially actuated, wherein the inertia of the friction pads 68a, 68b actuates the centrifugal clutch 34 in response to changes in rotational speed.

[0107] The engagement surface 38a of the clutch drum 38 has a diameter of approximately 70 mm. The friction pads 68a and 68b each weigh approximately 40 g, and each coil spring 70a and 70b has a corresponding spring constant of approximately 40 N / m. Therefore, the centrifugal clutch 34 is capable of transmitting torque at a slip limit speed of approximately 2 N / m.

[0108] Obviously, although two friction pads 68a, 68b and two helical springs 70a, 70b are shown in the embodiment, other numbers of friction pads and springs may also be used. Furthermore, other elastic elements besides the helical springs may also be used to radially inward bias the friction pads 68a, 68b. In fact, for the purposes of this disclosure, the helical springs 70a, 70b or any other elastic element for radially inward biasing the friction pads 78a, 78b may be optional, as the helical springs 70a, 70b are not necessary to allow the clutch to move between a locked state and a slippery engaged state. The centrifugal clutch 34 operates as a slipper clutch, i.e., in some cases, it allows slippage between the drive member 36 and the driven member 38. Due to the slippery capability, even the saw chain 16 ( Figure 1A Even if the motor 22 is stuck, it can still continue to operate. As explained in this article, this provides several benefits.

[0109] Now for reference Figure 7CThe rotor 52 (schematically shown by the dashed circle) has an outer rotor diameter D1, and the output shaft 30 has a shaft diameter D2 at its axial position relative to the bearing 58. When combined with the slipper clutch 34, an exemplary suitable ratio D1 / D2 between the rotor diameter D1 and the shaft diameter D2 is between 2.5 and 4.8; in the illustrated embodiment, it is approximately 4. The engagement surface 38a of the clutch drum 38 has a clutch engagement surface diameter D3, and an exemplary suitable ratio D1 / D3 between the rotor diameter D1 and the clutch engagement surface diameter D3 is between 0.50 and 1.2; in the illustrated embodiment, it is approximately 0.75. The illustrated output shaft 30 has a diameter D2 of approximately 12 mm at its axial position relative to the bearing 58. (As from, for example...) Figure 3B As can be clearly seen, the cooling fan 46 has an outer diameter that exceeds the diameter of the motor housing 62a, which improves the flow of cooling air to the centrifugal clutch 34.

[0110] Figure 7D The cross-sectional view particularly shows the worm gear drive 42, and the meshing engagement between the worm 42a and the worm wheel 42b driven by the worm 42a.

[0111] Figure 8A and Figure 8B The schematic diagram shows the electric motor 22 ( Figure 3A The rotational speed ω m Centrifugal clutch 34 (function) Figure 3A The exemplary general behavior of the drive member 36. The rotational speed ω of the drive member 36. C1 Follow the rotational speed ω of motor 22 m The rotational speed ω of the driven component 38 C2 Depends on clutch 34 ( Figure 3A The status of the saw chain 16 ( Figure 1A The load on the motor 22. When the motor 22 starts, at low speed, the centrifugal clutch 34 is in a disengaged state, that is, the friction pads 68a and 68b run freely without engaging with the clutch drum 38. When the engagement speed ω is reached... E At that time, friction tiles 68a, 68b ( Figure 7A The clutch engagement surface 38a of the clutch drum 38 begins to engage with the clutch. Figure 7A ) engage and slide against it. When the velocity ω C1 When increased, the slip torque T of the centrifugal clutch 34 s That is, the torque required to make the driving member 36 slide relative to the driven member 38 also increases.

[0112] Here, two different scenarios can be considered. In both cases, it is assumed that the motor operates at its maximum torque T suitable for extended operation. m Operation. In the first case, such as Figure 8AAs shown, saw chain 16 ( Figure 1A ) along guide rod 18 ( Figure 1A ) moves freely, and the velocity ω of the driven component 38 C2 It will soon reach the speed ω of the driving component 36. C1 That is, stop sliding.

[0113] exist Figure 8B In the second case shown, saw chain 16 ( Figure 1A It can, for example, be caught in the saw kerf, or otherwise prevented from moving along guide rod 18. Figure 1A ( ) Operation. In this case, as long as the torque required to move the saw chain 16 exceeds the torque T of the motor 22. m The velocity ω of the driven component 38 C2 It will remain at zero. The rotational speed ω of the driving component 36 C1 And the rotational speed ω of motor 22 m It will not be possible to reach a speed higher than the sliding limit ω. L At higher speeds, the slip torque T of the centrifugal clutch 34 at this slip limit speed s Equal to motor torque T m .

[0114] Then consider the transition from the first unloaded case to the second loaded case: if motor 22 travels at a speed higher than the sliding limit ω... L rotational speed ω m The saw chain 16 is operated and exposed to a gradually increasing load that increases until it exceeds the motor torque T. m Then the driving member 36 and the driven member 38 will remain locked to each other, and their corresponding rotational speeds ω C1 ω C2 They will follow each other down to their sliding limit speed ω L At this sliding limit speed, the driven member 38 suddenly and completely stops, while the driving member 36 remains at the sliding limit speed ω. L .

[0115] Engagement speed ω E and the sliding limit speed ω L An exemplary value could be, for example, ω. m = Approximately 5000 rpm and ω L = Approximately 6500 rpm. For completeness, the slip limit speed ω is calculated due to the frictional hysteresis of clutch slippage. L The sliding limit can be determined based on whether it is a higher or lower speed ω of the driven component 36. C1 Similar but slightly different; for simplicity, this effect is ignored here.

[0116] The speed range of motor 22 is from 0 to ω EIn this state, the centrifugal clutch is disengaged, and the electric motor 22 operates without moving the saw chain 16. This disengaged state allows the electric motor 22 to be used for various purposes without moving the saw chain 16. For example, the electric motor 22 can operate at speeds below the engagement speed ω. E The speed is determined by the operator via trigger 24 ( Figure 1A ) Operation or controlled by controller 23 ( Figure 1A It operates automatically to cool the engine after performing a powerful cut.

[0117] From ω of motor 22 E to ω L Within the specified speed range, the centrifugal clutch is in a slip-permissible state, where excessive load causes or increases slippage of the centrifugal clutch 34. In other words, even when in a slip-permissible state, the centrifugal clutch 34 can still exhibit slippage, i.e., begin to slip. Moreover, the slip-permissible state enables new features and functions of the electric motor 22. For example, when the operator presses the saw chain 16 too hard against the material to be cut, slippage generates an audible warning to alert the operator to the slippage state, allowing the operator to reduce pressure.

[0118] Above ω L During the speed range of the electric motor 22, the centrifugal clutch 34 is in a locked state, where excessive load causes the speed ω of the electric motor 22 to increase. m Reduce without slipping.

[0119] The state of the centrifugal clutch enables various control methods, which can be implemented in the control logic 23c of the controller 23. The control logic 23c, which can be implemented in a microcontroller, includes memory and a processor for executing the various control methods. The controller 23 can also be configured to automatically detect slippage, i.e., actual slippage or at least suspected slippage of the clutch 34. This can be achieved, for example, by detecting the slippage limit speed ω. L Operations exceeding the time limit, and detection of attempts to reach the set speed ω s The motor 22 must not exceed the sliding limit speed ω L Or by controlling the motor speed ω m The ω of the driven member 38 is detected from the driven member 38. C2 The rotational speed ω is received by a separate rotation sensor (not shown). C2 This is achieved through comparison. For example, controller 23 ( Figure 5 It can be configured so that when the speed ω of motor 22... m Descending to the limit speed (e.g., engagement speed ω) E Or a separately defined electric brake release speed ω RRelease the inductive brake 23e when the following conditions are met. Figure 5 ).

[0120] Figure 9 A handheld battery-powered chainsaw 110 according to a second embodiment is shown. The sprocket cover 26 of the chainsaw 110 is shown again. Figure 1A ) was removed, except Figure 9 The chainsaw 110 includes, in addition to the transmission device 128 according to the second embodiment, the chainsaw 110 is different from the chainsaw 10 of the first embodiment. Figure 1A The same transmission device replaces the transmission device 28 described with reference to the chainsaw 10 of the first embodiment. Figure 9 The transmission device 128 also includes a sliding centrifugal clutch 34.

[0121] Figure 10 To correspond to Figure 3B The view shows more detail. Figure 9 The electric motor 22 and the transmission device 128, and Figure 11 The exploded view shows more details. Figure 10 The transmission device 128. Figure 10 The transmission 128 does not have a separate brake drum. Instead, the clutch drum 38 also operates as the brake drum 40a, and the brake band (not shown) is provided by a handguard device 25 that engages with the outer cover of the clutch drum 38. Figure 9 ) operation. For example Figure 3B In the different embodiment shown, the saw chain drive sprocket 32 ​​is rigidly connected to the clutch drum 38 on the distal side 34B of the centrifugal clutch 34. The clutch drum 38 is instead opened towards the proximal side 34a of the clutch 34 to receive the drive member 36 from the proximal side 34a. Similar to the first embodiment 28, the drive member 36 includes a set of friction pads 68a, 68b and a friction pad guide 72 driven, for example, via a spline 31a, by the output shaft 30 of the electric motor 22. Figure 10 In the view, the position of the drive member 36 is schematically indicated by dashed lines. The clutch drum 38 and the worm gear 42a for driving the saw chain oil pump are rotatably journaled on the output shaft 30 so that they can rotate independently of the drive member 36. A metal wire spring 43a is attached to the worm gear 42a. Figure 10 ) and the notch 43b in the clutch drum 38 Figure 11 The worm gear 42a engages with the clutch drum 38, causing them to rotate together. The saw chain drives the sprocket 32 ​​and the clutch drum 38 through the head 33 of the screw that engages with the output shaft 30. Figure 10 It is axially held on the output shaft 30 of the motor 22.

[0122] Figure 12The electric motor 22 and transmission device 228 according to the third embodiment are schematically shown. Transmission device 228 can replace chainsaw 10. Figure 1A The transmission devices 28 and 128 described above in the third embodiment. The transmission device 228 according to the third embodiment includes an electromagnetic clutch 234, whose rotation axis is concentric with the rotation axis A of the motor 22. The electromagnetic clutch 234 includes a drive member configured as a clutch rotor plate 236, a driven member configured as an armature plate 238, and a controller 23 (…). Figure 1A ) control logic 23c ( Figure 5 The controller 23 is configured to selectively actuate the clutch 234 by generating a current in the excitation coil 241, thereby magnetizing the clutch rotor plate 236. The magnetic field generated by the excitation 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 excitation coil 241, the clutch 234 can be in a disengaged state or an engaged state. In the disengaged state, the clutch rotor plate 236 rotates freely without causing the saw chain 16 ( Figure 1A The clutch 234, in the engaged state, transmits torque to move the saw chain 16. When engaged, the clutch 234 can be in a slip-allowed state and a locked state. In the slip-allowed state, the clutch rotor plate 236 can slide relative to the armature plate 238; in the locked state, the clutch 234 is configured to drive the saw chain 16 without slipping. Therefore, the controller 23 can selectively set the clutch in either of these states. Clearly, the control signal from the controller 23 to the excitation coil 241 provides the controller 23 with prior knowledge of whether the clutch 234 is engaged or disengaged. Alternatively, the clutch state sensor 74 can directly detect the state of the clutch 234, for example, by detecting the axial position of the armature plate 238, thereby enabling 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 By adjusting the rotational speed ω of the armature plate 238 C2 With the rotational speed ω of motor 22 m By comparing the values, controller 23 can determine whether the clutch is slipping; therefore, rotation sensor 76 operates as a slip detector. According to some embodiments, the controller can be configured to operate based on the rotational speed ω of motor 22. m This allows clutch 234 to switch between clutch states. Figure 1A ).therefore, Figure 12 The electromagnetic clutch 234 can be configured to, for example, interact with... Figure 6A The centrifugal clutch 34 operates in a similar manner. The engagement speed ω used to transition between clutch states... E and the sliding limit speed ω LThis can be optionally set by the operator via user interface 27. In fact, it can be set according to the speed ω. m Different limit speeds can be set by increasing or decreasing them. For example, the controller can be configured to set an engagement speed ω. E This causes clutch 234 to transition from the disengaged state to the engaged state at a disengagement speed ω. D The clutch 234 is switched from the engaged state to the disengaged state at a disengagement speed ω. D It can be related to the engagement speed ω E Different. Controller 23 ( Figure 5 It can be further configured to release the inductive brake 23e as soon as the electromagnetic clutch 234 is disengaged. Figure 5 ).

[0123] Figure 13 The transmission device 328 according to the fourth embodiment is schematically shown. The transmission device 328 can replace the chainsaw 10. Figure 1A The transmission devices 28, 128, and 228 described above in the fourth embodiment. The transmission device 328 according to the fourth embodiment includes an electromechanical clutch configured as a belt clutch 334. The belt clutch 334 includes a drive member and a driven member, the drive member being configured to be attached to a drive shaft 30 to drive a motor 22 ( Figure 1A The drive pulley 336 receives rotational power, and the driven member is configured as a driven pulley 338 attached to the saw chain drive sprocket 32. In the illustrated embodiment, the drive member 336 and the driven member 338 can rotate about parallel axes of rotation, but the axes of rotation are not concentric. The drive pulley 336 and the driven pulley 338 are connected by a drive belt 337, the tension of which can be controlled by adjusting the position of the idler pulley 339. Depending on the tension in the drive belt 337, the clutch 334 can be in a disengaged state and an engaged state. In the disengaged state, the drive pulley 336 rotates freely without causing the saw chain 16 to rotate. Figure 1A In the engaged state, the clutch 334 transmits torque to move the saw chain 16. When engaged, the clutch 334 can be in a slip-allowed state and a locked state. In the slip-allowed state, the drive pulley 336 can slide relative to the driven pulley 338. In the locked state, the clutch 334 is configured to drive the saw chain 16. Figure 1A Without slipping. The idler wheel 339 is activated by the clutch actuator 341 in response to the controller 23 ( Figure 1A The clutch moves in response to a control signal generated by the control logic 23c. Therefore, the controller can selectively set the clutch to any of the aforementioned states.

[0124] Figure 14A further transmission device 428 according to the fifth embodiment is schematically shown, which can replace the transmission devices 28, 128, 228, and 328 described above. The transmission device 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 an idler wheel 439 for selective engagement between the drive wheel 436 and the driven wheel 438. Furthermore, the idler wheel 439 responds to a control 23 (… Figure 1A The control logic 23c generates a control signal that moves the clutch actuator 341, thereby enabling the controller 23 to set the clutch 434 in any of the aforementioned states.

[0125] Figure 15 A first method for controlling the electric motor 22 to selectively drive the saw chain 16 is shown.

[0126] In the first method step 1001, the controller determines the state of clutches 34, 234, 334, and 434. The state of the clutches can be determined, for example, by determining the speed of the motor 22 in the case of a speed-actuated clutch, by determining the set state of the clutch in the case of an electromagnetic or electromechanical clutch, or by detecting the actual slip state as described above.

[0127] In the second method step 1002, the controller 23 adjusts the torque T of the electric motor based on the determined clutch state. m and / or rotational speed ω m And / or alert the chainsaw operator.

[0128] According to the implementation, step 1001 may include, for example, determining a time period during which clutches 34, 234, 334, and 434 are in a slipping state or have been in a slipping state for more than a certain time limit. Step 1002 may include, for example, turning on a light, emitting an alarm sound, or, according to a predetermined pattern, changing the rotational speed ω of motor 22. m and / or torque T m The alarm is triggered to the operator by running motor 22. The rotational speed ω of motor 22 is... m and / or torque T m The pulse can be applied by, for example, an audible or tactilely perceptible pulse frequency. In the case of the centrifugal clutch 34, the torque T... m At the sliding limit speed ω m Applying a pulse nearby can help get a stuck saw chain back into motion.

[0129] According to another embodiment, step 1001 may again include, for example, determining a time period during which clutches 34, 234, 334, and 434 are in a slipping state or have been in a slipping state for an extended period of time. Step 1002 may include, for example, temporarily reducing the torque T of the motor 22. m Increase to exceed the maximum torque T allowed for continuous operation of the motor. max excess torque T + Therefore, the temporary increase in torque T + This can cause the jammed saw chain 16 ( Figure 1A It is able to move.

[0130] According to another embodiment, step 1001 may again include, for example, determining a time period during which clutches 34, 234, 334, and 434 are in a slipping state or have been in a slipping state for more than a limited time. Step 1002 may include reducing the motor torque T of motor 22. m and / or rotational speed ω m For example, in a speed-actuated clutch (e.g., a centrifugal clutch 34) Figure 3A In the case of ), controller 23 can ignore the signal from trigger 24. Figure 1A Any input, and automatically adjusts the rotational speed ω. m Reduce to the engagement speed ω of clutch 34 E The controller can be configured to suppress rotational speed ω. m Further increase to the engagement speed ω E The above continues until the operator first releases trigger 24 and then presses it again.

[0131] According to another embodiment, step 1001 may again include, for example, determining a time period during which clutches 34, 234, 334, and 434 are in a slipping state or have been in a slipping state for a limit time. Step 1002 may include, firstly, if the trigger remains fully depressed, changing the rotational speed ω of motor 22 for a finite time. m and / or torque T m And thereafter ignore any input from trigger 24 and automatically disengage clutches 34, 234, 334, 434, for example, in the case of centrifugal clutch 34 by adjusting the rotational speed ω. m Reduce to the engagement speed ω of motor 22 E the following( Figure 3A ).

[0132] According to another embodiment, step 1001 may include, for example, determining that clutches 34, 234, 334, and 434 are disengaged. Step 1002 may include operating the motor 22 at a predetermined speed suitable for operating the cooling fan 46, and / or reducing the motor torque T by reducing the current in the rotor windings 52a-52c. m This is to ensure low power consumption when operating fan 46.

[0133] Figure 16 A second method is shown for controlling the motor 22 to selectively drive the saw chain 16.

[0134] In step 2001, the controller detects trigger 24 ( Figure 1A The motor 22 is in the fully released position, thereby operating the fan 46. Figure 3A ).

[0135] In step 2002, via controller 23 ( Figure 5 The controller 23 detects the depressing of trigger 24 and, in response, engages clutches 34, 234, 334, and 434, thereby causing the saw chain 16 ( Figure 1A Move and operate the saw chain oil pump.

[0136] In step 2003, the complete release of trigger 24 is detected by controller 23, and in response, controller disengages clutches 34, 234, 334, and 434, thereby stopping saw chain 16.

[0137] In step 2004, after the trigger 24 is fully released and the clutches 34, 234, 334, and 434 are disengaged, the controller keeps the motor 22 running, thereby keeping the fan 46 running.

[0138] According to one embodiment, in steps 2001 and / or 2004, controller 23 may be configured to operate motor 22 based on a further condition that a temperature reading from a temperature sensor exceeds a limit temperature, such as motor temperature sensor 57 or controller temperature sensor 23g. Controller 23 may also, or alternatively, be configured to maintain operation of motor 22 for a predetermined time, e.g., 30 seconds, to allow the motor to cool after being cut off. Alternatively or additionally, controller 23 may be configured based on mechanical braking devices 40a, 40b ( Figure 3A The state of the motor 22 is such that, for example, the motor 22 is operated based on another condition based on the engagement of the mechanical braking devices 40a and 40b.

[0139] In a speed-driven clutch (e.g., centrifugal clutch 34) Figure 3A In the case of ), in step 2002, the controller can control the rotational speed ω of the motor 22.m Increase the engagement speed ω of the centrifugal clutch 34 m The above engages clutch 34. In steps 2001 and / or 2004, controller 23 can be configured to operate at idle speed ω. i ( Figure 8A Operate the electric motor 22, the idle speed of which can be, for example, about 4000 rpm.

[0140] In an optional step 2000 preceding step 2001, controller 23 may automatically start operation of motor 22 without engaging slip clutch, for example, in response to chainsaw 10 being turned on via an on / off switch (not shown), and / or in response to detection that chainsaw 10 has been lifted, as indicated by, for example, an accelerometer (not shown), and / or in response to detection that one or both handles 14a, 14b have been gripped by the operator, as indicated by, for example, a capacitive sensor (not shown) at handles 14a, 14b.

[0141] Figure 17 A further transmission device 528 according to the sixth embodiment is schematically shown, which can replace the one described above. Figure 1A The transmission devices 28, 128, 228, 328, and 428 described in the handheld battery-powered chainsaw 10 or 110. The transmission device 528 according to the sixth embodiment and... Figure 11 The difference in transmission 128 is that it does not include a clutch. Instead, brake drum 40a, worm gear 42a, and saw chain drive sprocket 32 ​​are coupled to always rotate with motor 22. Sprocket 32, brake drum 40a, and worm gear 42a are all splinedly engaged with output shaft 30. Figure 11 ), and is axially held in place by screws 33 and washers. Furthermore, in the illustrated embodiment, the motor 22 also drives the flywheel 90. The flywheel 90 is coupled to the rotor 54 of the motor 22 ( Figure 6AThe flywheel 90 rotates together around the flywheel's axis of rotation, which coincides with the axis of rotation A of the motor 22. Therefore, the flywheel 90 receives and stores angular momentum from the motor 22, which helps maintain the speed of the saw chain 16 (FIG. 1) when engaged with 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 facing away from the motor 22. An axial clearance 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 may be positioned on the proximal side of the fan 46, i.e., on the side of the fan 46 facing the motor 22. This configuration moves the mass and moment of inertia of the flywheel 90 closer to the lateral center of the chainsaw 10 (FIG. 1), which improves the flexibility of the chainsaw 10, i.e., the ease with which the operator can move the chainsaw 10 during operation. The flywheel 90 has a weight of approximately 125g and an outer diameter of approximately 90mm. Specifically, the flywheel 90 is configured as a steel inertia ring suspended from the output shaft 30 via spokes (not shown), such that the weight of the flywheel 90 is concentrated on the outermost radial portion of the flywheel 90 relative to the axis of rotation A. The spokes also allow axial airflow into the fan 46. Figure 17 In the implementation, rotor 54 ( Figure 6A The total moment of inertia J of all components rotating by rotor 54 is approximately 2.4 × 10⁻⁶. -4 kgm 2 All components include shaft 30, fan 46, brake drum 40a, worm gear 42a, saw chain drive sprocket 32, and flywheel 90. The flywheel 90 accounts for approximately 60% of the total moment of inertia, or approximately 1.4 x 10⁻⁶. -4 kgm 2 The total mass M of rotor 54 and all components rotating by rotor 54 is approximately 440g, which results in a mass-to-moment-of-inertia ratio J / M of approximately 5.5m. 2 A higher J / M ratio indicates high gravimetric efficiency in the inertial energy storage of the chainsaw 10.

[0142] Figure 18A and Figure 18B A flywheel 190 according to a second embodiment is shown, wherein the flywheel 190 is connected to Figure 3A and Figure 3B The transmission device 28 of the first embodiment shown includes a clutch 34. Figure 18B The flywheel 190 is shown as seen along the rotation axis A of the motor 22. Figure 18A and Figure 18BThe flywheel 190 includes an inertia ring 190a directly attached to the blades 50 of the fan 46. Therefore, the blades 50 of the fan 46 also function as spokes, holding the mass of the inertia ring 190 at a radial distance from the axis of rotation A. The blades 50 can be made of a relatively lighter material, such as aluminum or plastic, while the inertia ring can be made of a relatively heavier material, such as steel or copper. Figure 18A It is clearly visible that the inertia ring 190a extends to 100% of the total radius of the flywheel 190, that is, it defines the outermost radial edge of the flywheel 190. Although Figure 18A and Figure 18B The combined fan 46 and flywheel 190 are shown, but it is clear that in order to increase the moment of inertia of the transmission without excessively increasing the static weight of the transmission, weight can also be added to the radially outermost portion of the other rotating parts of the transmission 28.

[0143] Figure 19 A computer-readable storage medium implemented as a CD (optical disc) 99 is shown. The CD 99 stores a computer program product including instructions that, when implemented on a processor, perform any of the methods defined above.

[0144] The invention has been described above with reference to several embodiments. However, as will be readily understood by those skilled in the art, other embodiments besides those disclosed above are also possible within the scope of the invention as defined by the appended claims.

[0145] For example, the invention has been described with reference to rear-handle type chainsaws. However, it will be understood that the teachings herein are equally applicable to top-handle type chainsaws.

[0146] 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.

Claims

1. A handheld battery-powered chainsaw (10; 110), comprising: Electric motor (22), and The transmission device (28; 128; 228; 328; 428) is connected to the motor (22), wherein, The electric motor (22) is configured to drive the saw chain (16) via the transmission device (28; 128; 228; 328; 428). The transmission device (28; 128; 228; 328; 428) is characterized in that it includes a sliding clutch (34; 234; 334; 434), the sliding clutch (34; 234; 334; 434) including a drive member (36; 236; 336; 436) configured to receive rotational power from the electric motor (22) and a driven member (38; 338; 238; 438) configured to transmit rotational power to the saw chain (16), wherein the sliding clutch (34; 234; 334; 434) is configured to slide when engaged between the drive member (36; 236; 336; 436) and the driven member (38; 238; 338; 438), thereby disengaging the electric motor (22) from the saw chain (16) at least partially; The handheld battery-powered chainsaw (10; 110) further includes a controller (23) and a trigger (24) movable between a depressed position and a released position. In response to the depressed position, the motor (22) operates to move the saw chain (16), and in response to the released position, the saw chain (16) stops. The controller (23) is configured to, when the rotational speed ω of the motor (22) has been set... m Reduce to clutch engagement speed ω E From this point onward, it is forbidden to increase any speed to the sliding limit speed ω. L Until the trigger (24) has been released and then pressed down again.

2. The handheld battery-powered chainsaw (10; 110) according to claim 1, wherein, The transmission device (28; 128; 228) is configured to provide a 1:1 transmission ratio between the electric motor (22) and the saw chain sprocket meshing with the saw chain (16).

3. The handheld battery-powered chainsaw (10; 110) according to any one of the preceding claims, wherein, The slip clutch is configured to transmit a slip torque between 2 Nm and 4.5 Nm during slippage.

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

5. The handheld battery-powered chainsaw (10; 110) according to claim 4, wherein, The slip clutches (34; 234; 334; 434) are configured to respond to the rotational speed ω of the drive member (36; 236; 336; 436). C1 The state changes and transitions between the engaged state and the disengaged state.

6. The handheld battery-powered chainsaw (10; 110) according to any one of claims 4 to 5, wherein, The slip clutches (34; 234; 334; 434) are configured to respond to the rotational speed ω of the drive member (36; 236; 336; 436). C1 The drive member (36; 236; 336; 436) can slide relative to the driven member (38; 238; 338; 438) in the sliding state, while the sliding clutch (34; 234; 334; 434) is configured to drive the saw chain (16) without sliding in the locking state.

7. The handheld battery-powered chainsaw (10; 110) according to claim 6, wherein, The slipper clutches (34; 234; 334; 434) are configured to engage at a predetermined clutch speed ω. E The slip clutch (34; 234) transitions between the disengaged state and the engaged state at speeds above the engagement speed. 334; 434) presents the engagement state, and the slip clutch is configured to operate at a predetermined slip limit speed ω. L When the sliding clutch (34; 234) transitions from the allowed sliding state to the locked state above the sliding limit speed, the sliding clutch (34; 234; 334; 434) presents the locked state, wherein the sliding limit speed ω L Compared to the engagement speed ω E At least 200 rpm.

8. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The slipper clutch is inertial actuated.

9. The handheld battery-powered chainsaw (10; 110) according to any one of claims 4 to 5, wherein, The slip clutch is configured as a centrifugal clutch (34).

10. The handheld battery-powered chainsaw (10; 110) according to claim 9, wherein, The driven member (38; 338; 238; 438) includes a clutch drum (38) having a diameter between 60 mm and 90 mm, and the drive member includes a set of two or three friction pads (68a, 68b) elastically connected to each other by elastic elements (70a, 70b), wherein each of the friction pads (68a, 68b) has a corresponding weight between 30g and 70g, and each of the elastic elements (70a, 70b) has a spring constant between 35 N / mm and 60 N / mm.

11. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The slip clutch (34; 234; 334; 434) has a proximal side (34b) facing the motor (22) and a distal side (34a) facing away from the motor (22), 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) on the distal side (34a) of the slip clutch (34; 234; 334; 434).

12. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The slip clutch (34; 234; 334; 434) has a proximal side (34b) facing the motor (22) and a distal side (34a) facing away from the motor (22), wherein a saw chain drive sprocket (32) is connected on the proximal side of the slip clutch (34; 234; 334; 434) to the driven member (38; 238; 338; 438) of the slip clutch (34; 234; 334; 434).

13. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The electric motor (22) has: The rotor (54) is configured to rotate by the stator (52), the rotor (54) having an outer rotor diameter D1, and An output shaft (30) is drivably connected to the drive member (36; 236; 336; 436) of the sliding clutch (34; 234; 334; 434), the output shaft (30) having a shaft diameter D2. The ratio D1 / D2 between the rotor diameter D1 and the shaft diameter D2 is between 2.5 and 4.

8.

14. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The slipper clutch is electromagnetically actuated based on a clutch control signal.

15. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, further comprising a mechanical braking device (40a, 40b) movable between a braking position and a release position, wherein in the braking position the mechanical braking device (40a, 40b) is configured to engage with the transmission device (28; 128; 228; 328; 428) to brake the rotation of the driven member (38; 238; 338; 438), and in the release position the driven member (38; 238; 338; 438) is free to rotate.

16. The handheld battery-powered chainsaw (10; 110) according to claim 15, further comprising a rear handle (14b), the rear handle (14b) being provided with a trigger (24) for operating the motor (22), wherein, The mechanical braking devices (40a, 40b) are configured to operate independently of the position of the trigger (24).

17. The handheld battery-powered chainsaw (10; 110) according to claim 15, wherein, The driven member includes a clutch drum (38), and wherein the mechanical braking device (40a, 40b) includes a brake band (40b) configured to apply a clamping force on the radially outer surface of the clutch drum (38) in response to actuation of the brake actuator.

18. The handheld battery-powered chainsaw (10; 110) according to claim 15, wherein, The mechanical braking device (40a, 40b) includes a brake band (40b) and a brake drum (40a) axially separated from the slip clutch (34; 234; 334; 434), the brake band (40b) being configured to apply a clamping force on the radially outer surface of the brake drum (40a) in response to actuation of the brake actuator.

19. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, further comprising an electrically controlled brake.

20. The handheld battery-powered chainsaw (10; 110) according to claim 19, wherein, The electric brake is an electromagnetic brake and / or an inductive brake.

21. The handheld battery-powered chainsaw (10; 110) according to claim 19, wherein, The electric brake is configured to apply braking force to the electric motor (22), to the drive member (36; 236; 336; 436), and / or to any element fixedly attached to the electric motor (22) or the drive member (36; 236; 336; 436).

22. The handheld battery-powered chainsaw (10; 110) according to claim 19, wherein, The chainsaw (10; 110) is configured to respond to the rotational speed ω of the electric motor (22). m Drop below the electric brake release speed ω R And release the electric brake.

23. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The electric motor (22) includes a rotor (54) configured to rotate about the motor rotation axis A, and the drive members (36; 236; 336; 436) are rotatably locked to the rotor (54) in a rotational shape-fit manner to prevent the drive members (36; 236; 336; 436) from rotating about the motor rotation axis A in two rotational directions.

24. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, further comprising a cooling fan (46), said cooling fan (46) being coupled to always operate together with the drive member side of said slip clutch (34; 234; 334; 434), wherein, The drive component side includes the electric motor (22), the drive component (36; 236; 336; 436), and / or any element fixedly attached to the electric motor (22) or the drive component (36; 236; 336; 436).

25. The handheld battery-powered chainsaw (10; 110) according to claim 24, wherein, The slip clutch (34; 234; 334; 434) is positioned on the first axial side (44a) of the motor (22), and the cooling fan (46) is positioned on the second axial side (44b) of the motor (22) opposite to the first axial side (44a).

26. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, further comprising a chainsaw oil pump, the chainsaw oil pump being coupled to receive power from the driven member (38; 238; 338; 438) side of the slip clutch (34; 234; 334; 434).

27. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The controller (23) is configured to operate the slip clutch (34; 234; 334; 434) between an engaged state and a disengaged state, in which the slip clutch (34; 234; 334; 434) is configured to drive the saw chain (16), and in which the drive member (36; 236; 336; 436) can rotate freely without driving the saw chain (16).

28. The handheld battery-powered chainsaw (10; 110) according to claim 27, wherein, The controller (23) is configured to maintain the operation of the electric motor (22) when the slip clutch (34; 234; 334; 434) is disengaged.

29. The handheld battery-powered chainsaw (10; 110) according to claim 28, wherein, The controller (23) is configured to keep the motor (22) running when the slip clutch (34; 234; 334; 434) is disengaged, thereby operating the cooling fan (46) of the chainsaw (10; 110) based on the condition that the detected temperature exceeds the limit temperature.

30. The handheld battery-powered chainsaw (10; 110) according to any one of claims 28 to 29, wherein, The chainsaw (10; 110) further includes a trigger (24) movable between a depressed position and a released position, wherein in response to the depressed position the motor (22) operates to move the saw chain (16) and in response to the released position the saw chain (16) stops, wherein the controller (23) is configured to enable the motor (22) to operate when the trigger (24) is in the released position.

31. The handheld battery-powered chainsaw (10; 110) according to claim 30, wherein, The controller (23) is configured such that when the trigger (24) is in the released position, the motor (22) can be operated based on the condition that the mechanical braking device (40a, 40b) configured to brake the driven member (38; 238; 338; 438) is engaged.

32. The handheld battery-powered chainsaw (10; 110) according to any one of claims 28 to 29, wherein, The controller (23) is configured as follows: By detecting a speed below the sliding limit ω L The extended operation is used to detect excessive clutch slip at the slip limit speed ω. L At the above time, the slip clutches (34; 234; 334; 434) are in a locked state; and In response to the detection of excessive clutch slip, a change is applied to the control signal used to operate the electric motor (22).

33. The handheld battery-powered chainsaw (10; 110) according to claim 32, wherein, Applying the change to the control signal used to operate the motor (22) includes adjusting the torque T delivered by the motor (22). m Apply a pulse, and / or change the rotational speed ω of the motor (22). m .

34. The handheld battery-powered chainsaw (10; 110) according to claim 33, wherein, The controller (23) is configured to control the torque T delivered by the motor (22). m The applied pulse does not exceed the limit time or the limit number of pulses, and thereafter the rotational speed ω of the motor (22) is... m Reduce to clutch engagement speed ω E the following.

35. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The motor (22) is an outer rotor including a rotating fixed stator with stator windings, the stator being radially surrounded by a rotor with a set of permanent magnets.

36. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The motor (22) is a vector-controlled permanent magnet motor.

37. The handheld battery-powered chainsaw (10; 110) according to any one of claims 1 to 2, wherein, The controller (23) is configured to detect an overload of the motor (22) and, in response to the overload, maintain or increase the torque T of the motor (22). m .

38. The handheld battery-powered chainsaw (10; 110) according to claim 7, comprising: Chainsaw body (12); A slender guide rod (18) is used to guide the saw chain (16), wherein, The extension direction of the guide rod (18) defines the longitudinal axis X. The guide rod (18) extends forward along the longitudinal axis X from the front end of the chainsaw body (12), wherein the guide rod (18) extends in the guide rod plane. Front handle (14a); and The rear handle (14b) has a trigger (24) on its bottom surface that enables the operator to operate the motor (22). A plane P parallel to the guide rod plane and including the last point (24a) of the trigger (24) intersects the vertex B of the front handle at a point, and the distance L between the intersection point and the last point (24a) of the trigger (24) exceeds 270 mm.

39. The handheld battery-powered chainsaw (10; 110) according to claim 38, wherein, The chainsaw (10; 110) is configured to run the motor (22) until the maximum output power E, wherein the ratio L / E between the distance L from the intersection to the last point (24a) of the trigger (24) and the maximum output power E exceeds 0.11 mm / W.

40. The handheld battery-powered chainsaw (10; 110) according to any one of claims 38 to 39, wherein, The chainsaws (10; 110) are configured to operate the electric motor (22) to generate an electric motor torque T. m Wherein, the motor torque T m At the sliding limit speed ω L The sliding torque T is reached at the point s The distance L from the intersection point to the last point (24a) of the trigger (24) is related to the sliding torque T. s The ratio between L / T s More than 90 mm / Nm.

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