Chainsaw and methods for determining and clearing chainsaw blockages

Abstract

This application discloses a cutting tool, specifically relating to a chainsaw, a method for unblocking the chainsaw, and a method for determining the blockage state of the chainsaw. The chainsaw includes a chain, a hydraulic pump assembly, a motor, and a controller. The chain is used to perform the cutting operation. The hydraulic pump assembly includes a hydraulic pump and a motor; the hydraulic pump is used to release liquid for lubricating or cooling the chain. The motor is used to drive the hydraulic pump. The controller is at least electrically connected to the motor. The controller is configured to: when the hydraulic pump is blocked, control the hydraulic pump assembly to enter a throttling mode that reduces the amount of liquid supplied; and when the hydraulic pump is unblocked, control the hydraulic pump assembly to exit the throttling mode. The technical solution provided by this application can determine and unblock the chainsaw.

Description

Technical Field

[0001] This application discloses a cutting tool, specifically relating to a chainsaw, a method for unblocking the chainsaw, and a method for determining the blockage state of the chainsaw. Background Technology

[0002] A chainsaw is a cutting tool primarily used for logging and timber processing. It utilizes the reciprocating motion of a chain to cut wood. Chainsaws are generally driven by a motor, and because the chain requires lubrication or cooling during its reciprocating motion, an oil pump and oil reservoir are installed inside the chainsaw. The oil pump drives the liquid in the oil reservoir through oil passages to the chain to lubricate or cool it. However, in actual use, the oil passages can become clogged, preventing the chain from being adequately lubricated or cooled, thus interfering with the operator's cutting work. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a chainsaw, a method for unblocking the chainsaw, and a method for determining the blocking status of the chainsaw, which can promptly unblock the chainsaw.

[0004] To achieve the above objectives, this application adopts the following technical solution:

[0005] This application provides a chainsaw, including a chain, a hydraulic pump assembly, a motor, and a controller. The chain is used to perform cutting operations. The hydraulic pump assembly includes a hydraulic pump and a motor, the hydraulic pump being used to release a liquid for lubricating or cooling the chain. The motor is used to drive the hydraulic pump. The controller is at least electrically connected to the motor. The controller is configured to:

[0006] When the pump is blocked, the pump assembly is controlled to enter a throttling mode that reduces the amount of liquid supplied; when the pump is cleared of blockage, the pump assembly is controlled to exit the throttling mode.

[0007] This application provides a method for unblocking a chainsaw, the chainsaw including a chain, a hydraulic pump, a motor, and a controller. The chain is used to perform cutting operations. The hydraulic pump is used to release liquid for lubricating or cooling the chain. The motor is used to drive the hydraulic pump. The controller is at least electrically connected to the motor. The method includes the steps of: when the hydraulic pump is blocked, controlling the hydraulic pump assembly to enter a throttling mode that reduces the amount of liquid supplied; and when the hydraulic pump is unblocked, controlling the hydraulic pump assembly to exit the throttling mode.

[0008] In some embodiments of methods for unblocking chainsaws, the motor includes a first motor and a second motor. The first motor drives the chain. The second motor drives the hydraulic pump. The method includes the following steps: when the hydraulic pump is blocked, controlling the second motor to be in an on / off mode or a low-power mode; when the hydraulic pump is unblocked, controlling the second motor to exit the on / off mode or the low-power mode. In the on / off mode, the second motor intermittently switches between a start-up state and a stop-down state; in the low-power mode, the electrical parameters of the second motor are lower than a preset electrical parameter threshold.

[0009] This application provides a method for determining the blockage state of a chainsaw, the chainsaw including a chain, a hydraulic pump, a motor, and a circuit detection module. The chain is used to perform cutting operations. The hydraulic pump is used to release liquid for lubrication or cooling of the chain. The motor is used to drive the hydraulic pump. The circuit detection module is used to detect the electrical parameters of the motor. The method includes the following steps: acquiring the amount or rate of change of the motor's electrical parameters within a preset detection time; determining that the chainsaw is in a blockage state when the amount of change of the electrical parameters is greater than or equal to a threshold value, or when the rate of change of the electrical parameters is greater than or equal to a threshold value; and determining that the chainsaw has exited the blockage state when the value of the motor's electrical parameters is within a preset range.

[0010] This application provides a chainsaw, including a chain, a hydraulic pump, a motor, and a controller. The chain is used to perform cutting operations. The hydraulic pump is used to release a liquid that lubricates or cools the chain. The motor is used to drive the hydraulic pump. The controller is at least electrically connected to the motor. The controller is configured to control the motor to cycle on and off: controlling the motor to start for an on duration and then controlling the motor to stop for an off duration.

[0011] The advantage of this application is that, upon determining that the oil circuit is blocked, the controller can control the motor to switch on and off at a certain frequency, thereby reducing the frequency at which the hydraulic pump releases the fluid used to lubricate or cool the chain. Alternatively, the controller can reduce the motor's operating power, thus reducing the amount of fluid released by the hydraulic pump per cycle for lubrication or cooling the chain. By reducing the hydraulic pump's operating frequency or power, the amount of fluid output by the pump will decrease, and the blockage in the oil circuit will gradually be alleviated. Attached Figure Description

[0012] Figure 1 This is a perspective view of a chainsaw according to an embodiment of this application;

[0013] Figure 2 yes Figure 1 A 3D view of the chainsaw after part of its outer casing has been removed;

[0014] Figure 3 yes Figure 2 Partial front view of the structure shown;

[0015] Figure 4 This is a block diagram of the control module of a chainsaw according to this application;

[0016] Figure 5 This is a flowchart illustrating a control method for starting a second motor in a chainsaw according to this application;

[0017] Figure 6 This is a flowchart illustrating a control method for determining whether a liquid pump is blocked in a chainsaw according to this application;

[0018] Figure 7 This is a flowchart illustrating a control method for unblocking a chainsaw according to this application;

[0019] Figure 8 This is a flowchart illustrating another control method for unblocking a chainsaw according to this application. Detailed Implementation

[0020] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] like Figures 1 to 3 As shown, this application provides a chainsaw 10, which includes a chain 100, a first motor 300, a housing 200, and a hydraulic pump assembly 400. The chain 100 is used to perform cutting operations. The first motor 300 is used to drive the chain 100 to perform operations, and the first motor 300 has advantages such as small size and easy installation as a driving component. The housing 200 forms a grip portion 210 for the user to hold, and the user can operate the chainsaw 10 by holding the grip portion 210. A mounting cavity is formed inside the housing 200, and a portion of the mounting cavity extends into the grip portion 210. The hydraulic pump assembly 400 is used to cool or lubricate the chain 100.

[0022] Specifically, the liquid pump assembly 400 includes a liquid pump 410, which is used to release liquid to lubricate or cool the chain 100. It should be noted that the liquid here can be lubricating oil to lubricate the chain 100, and correspondingly, the liquid pump 410 is selected as an oil pump; or, the liquid here can also be cooling water to cool the chain 100, and correspondingly, the liquid pump 410 is selected as a water pump.

[0023] In some specific embodiments, the liquid pump 410 can be driven by the first motor 300, that is, the first motor 300 is connected to both the chain 100 and the liquid pump 410 simultaneously through a transmission assembly, thereby achieving simultaneous driving of both the chain 100 and the liquid pump 410. Optionally, the transmission assembly can be a gear mechanism or a sprocket mechanism, etc., as needed.

[0024] Of course, in some parallel embodiments, the chainsaw 10 also includes a second motor 420, the motor shaft of which is connected to the liquid pump 410, and the second motor 420 is used to drive the liquid pump 410. Compared with using the first motor 300 to drive both the chain 100 and the liquid pump 410 simultaneously, the additional provision of a separate second motor 420 as the driving component of the liquid pump 410 not only eliminates the need for complex transmission components, but also makes it easier to arrange the second motor 420 within the mounting cavity of the housing 200 due to its small footprint, and facilitates full utilization of the space within the housing 200, thereby contributing to the miniaturization of the chainsaw 10.

[0025] like Figure 3 As shown, the chainsaw 10 also includes a battery pack coupling portion 500 for attaching a battery pack. Optionally, the battery pack is detachably connected to the battery pack coupling portion 500, making it easy to remove for replacement or charging. Of course, in addition to powering the second motor 420, the battery pack can also power the first motor 300. Besides using the battery pack as a power source, the first motor 300 and the second motor 420 can also be directly connected to mains power via power cables to achieve power supply.

[0026] Continue to refer to Figure 2 and Figure 3 As shown, a circuit board 600 is provided at the battery pack junction 500. The circuit board 600 is used to control the second motor 420, for example, to control the rotational speed of the second motor 420. Specifically, an insertion cavity is formed in the battery pack junction 500, and the circuit board 600 is inserted into the insertion cavity.

[0027] Of course, circuit board 600 can also be used to simultaneously control the first motor 300, for example, to control the rotational speed of the first motor 300. Using one circuit board 600 to simultaneously control the first motor 300 and the second motor 420 reduces the number of circuit boards 600 used, which not only reduces costs but also reduces the space occupied within the housing 200.

[0028] In some embodiments, such as Figure 2As shown, the second motor 420 is disposed in the grip 210. By placing the second motor 420 in the mounting cavity corresponding to the grip 210, the layout can be made more reasonable. This not only makes use of the mounting cavity corresponding to the grip 210, but also makes the weight of the chainsaw 10 more balanced, making it easier for the user to use.

[0029] Optionally, continue to refer to Figure 2 As shown, the liquid pump 410 is disposed within the grip portion 210, that is, the liquid pump 410 is disposed within the mounting cavity corresponding to the grip portion 210. Simultaneously disposing of the liquid pump 410 and the second motor 420 within the mounting cavity corresponding to the grip portion 210 facilitates direct connection between the second motor 420 and the liquid pump 410, avoiding the need for a transmission structure between the second motor 420 and the liquid pump 410 for power transmission.

[0030] Along the working direction of the chainsaw 10, the hydraulic pump 410 and the second motor 420 are arranged front and rear. This makes full use of the mounting cavity space within the grip 210 and facilitates the assembly of the hydraulic pump 410 and the second motor 420. Furthermore, along the working direction of the chainsaw 10, the hydraulic pump 410 is positioned in front of the second motor 420. Even further, both the hydraulic pump 410 and the second motor 420 extend along a predetermined direction, which forms a predetermined angle with respect to the horizontal direction. It should be noted that this predetermined angle can be an acute angle, an obtuse angle, or a right angle. Of course, the hydraulic pump 410 and the second motor 420 can also both extend vertically or both extend horizontally.

[0031] Reference Figure 2 and Figure 3 As shown, the liquid pump assembly 400 also includes an oil reservoir 700 and an oil passage. The oil passage may include a first oil passage 430 and a second oil passage 440. The liquid pump 410 has a first liquid port and a second liquid port. The first liquid port is connected to one end of the first oil passage 430, and the other end of the first oil passage 430 is placed in the liquid storage cavity formed by the chain 100. The second liquid port is connected to the oil reservoir 700 through the second oil passage 440. Driven by the liquid pump 410, the lubricating oil or cooling water stored in the oil reservoir 700 can enter the liquid pump 410 through the second oil passage 440 and enter the liquid storage cavity at the chain 100 through the first oil passage 430. When the chain 100 is working, the liquid in the liquid storage cavity can lubricate or cool the chain 100.

[0032] In some embodiments, the oil reservoir 700 is disposed within the grip portion 210, that is, within the mounting cavity corresponding to the grip portion 210. Disposing the oil reservoir 700 within the mounting cavity corresponding to the grip portion 210 not only utilizes the mounting cavity, resulting in a more balanced weight distribution across the chainsaw 10, but also brings the oil reservoir 700 closer to the hydraulic pump 410 disposed within the grip portion 210, thereby effectively shortening the required length of the second oil passage 440. Furthermore, the oil reservoir 700 is integrated into the inner wall surface of the housing 200, allowing the oil reservoir 700 to be formed simultaneously with the manufacture of the housing 200, reducing the likelihood of accidental detachment of the oil reservoir 700.

[0033] Reference Figure 4 As shown, in some embodiments, the chainsaw 10 may also include a temperature detection module 610, a controller 620, a speed detection module 630, a memory 650, a parameter reading module 660, and a circuit detection module 640.

[0034] The temperature detection module 610 can be used to detect the ambient temperature, the temperature of the first motor 300, the temperature of the second motor 420, or the temperature of the circuit board 600. Specifically, a temperature sensor can be set on the inner wall surface of the housing 200 to detect the ambient temperature inside the mounting cavity, or a temperature sensor can be set on or near the surface of the first motor 300 to detect the temperature of the first motor 300, or a temperature sensor can be set on or near the surface of the second motor 420 to detect the temperature of the second motor 420, or a temperature sensor can be set on or near the surface of the circuit board 600 to detect the temperature of the circuit board 600. Optionally, the temperature detection module 610 can acquire the ambient temperature detected by the temperature sensor set on the inner wall of the mounting cavity of the housing 200, and use the ambient temperature inside the mounting cavity of the housing 200 as the temperature of the chainsaw 10.

[0035] The controller 620 can be a single microcontroller or a combination of multiple distributed microcontrollers. The microcontroller can run a control program to control the first motor 300, the second motor 420, and other functional modules on the circuit board 600 to achieve their functions.

[0036] The speed detection module 630 can be used to detect the rotational speed of the first motor 300 and the rotational speed of the second motor 420.

[0037] The circuit detection module 640 can be used to detect the electrical parameters of the control circuit, which can be voltage or current values. Based on these voltage or current values, the change in voltage or current over a preset time period can be calculated. Specifically, it can detect the voltage and current values ​​of the first motor 300 or the second motor 420.

[0038] The memory 650 can be used to store preset parameters of the chainsaw 10. For example, empirical parameters, transmission ratios of the transmission components, and other data are pre-stored in the memory 650. The memory 650 can also be used to store parameters detected by the temperature detection module 610, the speed detection module 630, and the circuit detection module 650.

[0039] The parameter reading module 660 can be used to read data stored in the memory 650.

[0040] In some embodiments, the first motor 300 can simultaneously drive the chain 100 and the liquid pump 410. In this embodiment, the first motor 300 has a strong load capacity, and direct starting at normal low temperatures generally will not cause damage due to excessive load. However, in some embodiments, the first motor 300 drives the chain 100, and the second motor 420 drives the liquid pump 410. The load capacity of the second motor 420 is weaker than that of the first motor 300. In this embodiment, direct starting of the second motor 420 at low temperatures may cause damage due to excessive load. This application provides an implementation that can avoid damage due to excessive load when starting the second motor at low temperatures.

[0041] The controller 620 is electrically connected to the first motor 300 and the liquid pump assembly 400. Specifically, the controller 620 is electrically connected to the first motor 300, the second motor 420, and the temperature detection module 610. The controller is configured to control the start and stop of the first motor 300, control the start and stop of the second motor 420, and acquire the ambient temperature T0 detected by the temperature detection module 610.

[0042] The controller 620 is electrically connected to the temperature detection module 610 to obtain the ambient temperature T0. The ambient temperature T0 can be the ambient temperature inside the mounting cavity of the housing 200 detected by the temperature detection module 610. When the ambient temperature T0 is greater than the first temperature threshold T1, the controller 620 controls the second motor 420 to start.

[0043] When the temperature of the working environment of the chainsaw 10 is low, directly starting the second motor 420 will cause the current of the second motor 420 to be too high and the load to increase. In this embodiment, the second motor 420 is allowed to start only when the temperature is above the first temperature threshold T1, which can avoid the problem of excessive load and motor damage caused by direct starting at low temperature.

[0044] If the first temperature threshold T1 is too low, it will generate a large current when the second motor 420 starts; if the first temperature threshold T1 is too high, it will cause the operator to wait for a long time, affecting work efficiency. Considering the common working scenarios of the chainsaw 10, the first temperature threshold T1 can be set to be greater than or equal to -25°C and less than or equal to -5°C to balance the above conflicting requirements.

[0045] In some low-temperature environments, when the operator briefly turns off the chainsaw 10 after working for a period of time, heat continuously dissipates from the mounting cavity of the housing 200 during this period, causing the temperature to drop continuously. When the operator restarts the chainsaw 10, if the ambient temperature T0 is lower than the first temperature threshold T1, the second motor 420 cannot start immediately, and the operator needs to wait for a period of time before continuing to use the chainsaw 10. These situations affect the operator's work continuity.

[0046] The controller 620 obtains the restart time L0 of the chainsaw 10 by acquiring the restart time L0 after the first motor 300 is turned off. If the restart time L0 is greater than the preset waiting time L1, the controller 620 determines that the operator will not restart the chainsaw 10 in a short time, and the controller 620 controls the chainsaw 10 according to steps S110 and S120. If the restart time L0 is less than or equal to the preset waiting time L1, the controller 620 determines that the operator will restart the chainsaw 10 in a short time, and the second temperature threshold T2 for the controller 620 to control the restart of the second motor 420 should be lower than the first temperature threshold T1.

[0047] To provide a better user experience, in some embodiments, the controller 620 can also obtain the time length L0 after the first motor 300 is turned off and then restarted. If the time length L0 is less than or equal to the preset waiting time L1, and the ambient temperature T0 is greater than the second temperature threshold T2, the controller 620 controls the second motor 420 to start. The second temperature threshold T2 is lower than the first temperature threshold T1.

[0048] When the operator frequently starts the chainsaw 10 in a short period of time, the controller 620 lowers the temperature threshold for restarting the second motor 420 to the temperature threshold for the first start of the second motor 420, thereby reducing the temperature threshold for starting the second motor 420 and meeting the operator's need for work continuity.

[0049] If the second temperature threshold T2 is too low, the second motor 420 will also generate a large current when starting; if the second temperature threshold T2 is too high, the operator will have to wait for a long time, affecting work efficiency. Considering the common working scenarios of the chainsaw 10, the temperature difference between the second temperature threshold T2 and the first temperature threshold T1 can be set between 5°C and 15°C. Specifically, the first temperature threshold T1 can be -5°C, and the second temperature threshold T2 can be 0°C.

[0050] In some embodiments, the first motor 300 drives the chain 100 to perform operations, and the second motor 420 drives the liquid pump 410 to release liquid for lubrication or cooling of the chain 100. When the ambient temperature T0 is less than a first temperature threshold T1, the controller 620 can control the first motor 300 to start to drive the chain 100 to perform operations. Since the first motor 300 continuously generates heat during operation, the heat continuously accumulates in the mounting cavity of the housing 200, causing the temperature inside the mounting cavity of the housing 200 to rise, which in turn raises the temperature of the second motor 420. When the ambient temperature T0 detected by the temperature detection module 610 is greater than the first temperature threshold T1, the controller 620 can control the second motor 420 to start. Thus, the heat generated by the first motor 300 during operation can be used to heat the second motor 420, thereby avoiding the problem of excessive load caused by directly starting the second motor 420 at low temperatures.

[0051] In some embodiments, the installation positions of the first motor 300 and the second motor 420 can be specially configured so that the airflow formed after the first motor 300 starts passes through the second motor 420, thereby accelerating the heating rate of the second motor 420 and reducing the operator's waiting time. Optionally, the first motor 300 can be configured to allow convective heat transfer with the second motor 420, thereby accelerating the heating rate of the second motor 420. Optionally, the first motor 300 and the second motor 420 can be positioned close to each other to transfer heat from the first motor 300 to the second motor 420. Optionally, the distance between the first motor 300 and the second motor 420 can be greater than or equal to 30 mm and less than or equal to 150 mm. Specifically, the axial distance between the first motor 300 and the second motor 420 can be greater than or equal to 30 mm and less than or equal to 120 mm. Specifically, the axial distance between the first motor 300 and the second motor 420 can be equal to 100 mm. Setting the distance between the first motor 300 and the second motor 420 as described above allows the heat from the first motor 300 to be quickly transferred to the second motor 420 in low-temperature environments, thereby meeting the operator's need to quickly start the oil pump.

[0052] In some embodiments, using the ambient temperature within the mounting cavity of the housing 200 detected by the temperature detection module 610 as the temperature of the second motor 420 results in inaccurate temperature readings. Therefore, the temperature detection module 610 can directly detect the temperature of the second motor 420 to achieve a more accurate measurement. However, the surface of the second motor 420 is typically smooth, making it difficult to mount a temperature sensor. The circuit board 600 is located close to the second motor 420, has a smaller temperature difference, and its surface provides suitable space for mounting a temperature sensor. Therefore, the temperature detection module 610 can detect the temperature of the circuit board 600 and use this temperature as the temperature of the second motor 420.

[0053] Since the circuit board 600 also generates heat during operation, in some embodiments, the circuit board 600 can be configured to conduct heat with the second motor 420, thereby accelerating the heating rate of the second motor 420 and reducing the operator's waiting time. Optionally, the circuit board 600 and the second motor 420 can be connected by an electrically conductive wire, which can both transmit electrical signals and transfer heat from the circuit board 600 to the second motor 420.

[0054] like Figure 5 As shown, this application also provides a control method for starting the second motor 420 of the chainsaw 10, the control method including the following steps:

[0055] S110, Obtain the ambient temperature T0 output by the temperature detection module 610.

[0056] S120, Obtain the time L0 of the first motor 300 after it is turned off and then restarted.

[0057] S130. Determine if the time length L0 is greater than the preset waiting time L1. If L0 > L1, the controller 620 determines that the chainsaw is starting for the first time and proceeds to step S140. If L0 ≤ L1, the controller 620 determines that the chainsaw 10 is starting again within a short period of time and proceeds to step S150.

[0058] S140. Determine whether the ambient temperature T0 is greater than the first temperature threshold T1. If T0>T1, control the second motor 420 to start. If T0≤T1, control the second motor 420 to remain off.

[0059] S150. Determine whether the ambient temperature T0 is greater than the second temperature threshold T2. If T0 > T2, control the second motor 420 to start. If T0 ≤ T2, control the second motor 420 to be in the off state. The second temperature threshold T2 is lower than the first temperature threshold T1.

[0060] The above parameters, such as the preset waiting time L1, the first temperature threshold T1 and the second temperature threshold T2, can be pre-stored in the memory 650 and read by the parameter reading module 660.

[0061] In some working environments, the hydraulic circuit of the chainsaw 10 may become clogged. If the clog is not detected in time and measures are not taken to clear it, it may damage the chainsaw 10. This application provides an implementation method that can solve the problem of identifying and clearing hydraulic circuit blockages.

[0062] Since the voltage and current of the motor that drives the hydraulic pump 410 to release the liquid that lubricates or cools the chain 100 will change when the oil circuit is blocked, it is possible to determine whether the oil circuit of the hydraulic pump 410 is blocked by monitoring the amount or rate of change of the electrical parameters of the motor within a preset detection time L2.

[0063] In some specific embodiments, the first motor 300 can simultaneously drive the chain 100 and the hydraulic pump 410. Therefore, the amount or rate of change of the electrical parameters of the first motor 300 within a preset detection time L2 can be used to determine whether the oil circuit of the hydraulic pump 410 is blocked.

[0064] In some embodiments, the controller 620 of the chainsaw 10 is configured to acquire the amount or rate of change of the electrical parameters of the motor within a preset detection time L2. When the amount of change of the electrical parameters of the motor is greater than or equal to a preset threshold for the amount of change of electrical parameters, or when the rate of change of the electrical parameters of the motor is greater than or equal to a preset threshold for the rate of change of electrical parameters, the controller 620 determines that the hydraulic pump is blocked.

[0065] However, since the first motor 300 simultaneously drives both the chain 100 and the hydraulic pump 410, in cases where part of the chain 100 jams, the change in electrical parameters caused by the chain jamming might be misjudged as being caused by oil circuit blockage. In some embodiments, the motor may include a first motor 300 and a second motor 420, where the first motor 300 drives the chain 100 and the second motor 420 drives the hydraulic pump 410. The amount or rate of change of the electrical parameters of the second motor 420 within a preset detection time L2 can be used to determine whether the oil circuit of the hydraulic pump 410 is blocked, thereby avoiding misjudgment caused by chain jamming.

[0066] As previously described, whether the oil circuit is blocked can be determined by detecting the change or rate of change of the electrical parameters of the first motor 300, which in some embodiments simultaneously drives the chain 100 and the hydraulic pump 410, or the second motor 420, which in some embodiments drives the hydraulic pump 410. Therefore, in the description of the embodiments in this embodiment, when the term "motor" is used, it can refer to the first motor 300, which in some embodiments simultaneously drives the chain 100 and the hydraulic pump 410, or the second motor 420, which in some embodiments drives the hydraulic pump 410. When the term "second motor" is used, it refers to the second motor 420, which in some embodiments drives the hydraulic pump 410.

[0067] An excessively long preset detection duration L2 will affect the timeliness of the controller 620 in detecting oil circuit blockages. However, an excessively short preset detection duration L2 will place higher performance demands on the controller 620, thereby increasing the cost of the chainsaw 10. After multiple experiments by the applicant, setting the preset detection duration L2 to 20ms ≤ L2 ≤ 100ms can meet the needs of common working conditions and achieve a good balance between performance and cost.

[0068] Optionally, the electrical parameters can be the motor's voltage value U or current value I. The technology for measuring voltage value U or current value I is relatively mature in the existing market, and related instruments and devices are readily available and inexpensive. Measuring the motor's voltage value U or current value I allows for accurate measurement of the motor's electrical parameters, while also reducing the cost of the chainsaw 10.

[0069] When the circuit detection module 640 detects a change in one or more electrical parameters that is greater than or equal to a preset threshold for the change in the corresponding electrical parameter, or a change rate of one or more electrical parameters that is greater than or equal to a preset threshold for the change rate of the electrical parameter, the controller 620 determines that the oil circuit is blocked.

[0070] In some embodiments, a threshold value ΔI for the change in motor current when the oil circuit is blocked can be preset. fix And the threshold of voltage change ΔU fix The threshold RI of the rate of change of motor current fix and the threshold of voltage change rate RU fix .

[0071] In common working environments, a threshold value ΔI for current change can be set. fix ≥450mA or voltage change threshold ΔU fix ≥1V, or the current change rate threshold RI fix ≥4.5mA / ms or voltage change rate threshold RU fix The voltage is ≥0.01V / ms to meet most working conditions of the chainsaw 10. When the chain 100 works with different types of materials, different electrical parameters can be preset to adapt to the corresponding working conditions.

[0072] In addition to the aforementioned method of determining whether the oil circuit of the hydraulic pump 410 is blocked by monitoring the change in the electrical parameters of the motor, this application also provides a method for determining whether the oil circuit is blocked by monitoring the temperature of the chainsaw 10: When the oil circuit is blocked, the lubricant or coolant output by the hydraulic pump 410 cannot meet the lubrication or cooling requirements of the chain 100, thereby causing the temperature of the chainsaw 10 to rise. In some embodiments, it can be configured that if a sharp rise in the chain temperature is detected, it can be determined that the oil circuit of the hydraulic pump 410 is blocked.

[0073] This application also provides a method for unblocking a chainsaw 10 and a corresponding chainsaw 10. As previously mentioned, the "motor" may refer to a first motor 300 that simultaneously drives the chain 100 and the hydraulic pump 410 in some embodiments, or a second motor 420 that drives the hydraulic pump 410 in some embodiments.

[0074] The controller 620 of the chainsaw 10 can be configured to control the motor in an on / off mode when the hydraulic pump 410 is blocked. When the electrical parameter value is within a preset range, the controller 620 controls the motor to exit the on / off mode, wherein the motor intermittently goes through the on / off state.

[0075] The controller 620 of the chainsaw 10 can also be configured to control the value of the motor's electrical parameters to be lower than a preset electrical parameter threshold when the hydraulic pump 410 is blocked. When the value of the electrical parameters is within the preset range, the controller 620 controls the motor to exit the on / off mode, wherein the motor is intermittently in the on / off state.

[0076] After determining that the oil circuit is blocked, the controller 620 can control the pump assembly 400 to enter a throttling mode that reduces the amount of liquid supplied; when the pump 410 exits the blocked state, the controller 620 can control the pump assembly 400 to exit the throttling mode.

[0077] The controller 620 can control the motor to switch on and off at a frequency F, causing the liquid pump 410 to reduce the frequency of releasing the liquid that lubricates or cools the chain 100. Alternatively, the controller 620 can maintain the current I below or equal to a current threshold I. fix Or the voltage U is lower than or equal to the voltage threshold U fix This reduces the operating power of the hydraulic pump 410, thereby reducing the amount of liquid released by the hydraulic pump 410 each time to lubricate or cool the chain 100. After reducing the operating frequency or power of the hydraulic pump 410, the amount of liquid output by the hydraulic pump 410 will decrease accordingly, and the blockage in the oil circuit will gradually be alleviated.

[0078] Optionally, in some embodiments, after determining that the oil circuit is blocked, the controller 620 can control the motor to be in the on / off mode and control the value of the motor's electrical parameters to be lower than a preset electrical parameter threshold, thereby reducing the frequency of the liquid pump 410 releasing lubricating or cooling liquid and also reducing the amount of lubricating or cooling liquid released by the liquid pump 410 each time.

[0079] In some specific embodiments, the first motor 300 can simultaneously drive the chain 100 and the hydraulic pump 410. Therefore, by controlling the first motor 300 to be in an on / off mode and / or controlling the first motor 300 to be in a low-power state, the oil circuit can be gradually unblocked.

[0080] However, since the first motor 300 simultaneously drives both the chain 100 and the hydraulic pump 410, reducing the operating frequency or power of the first motor 300 will affect the cutting operation of the chain 100. In some embodiments, the motor may include a first motor 300 and a second motor 420, where the first motor 300 drives the chain 100 and the second motor 420 drives the hydraulic pump 410. By reducing the operating frequency or power of the second motor 420, the oil passage of the hydraulic pump 410 can be gradually unblocked, thereby avoiding any impact on the operation of the chain 100.

[0081] In some embodiments, the range of motor electrical parameter values ​​when the oil circuit is unblocked can be preset. Optionally, the electrical parameter value can be set to be within a preset range when it is N times a preset electrical parameter threshold. In some embodiments, the motor voltage threshold U when the oil circuit is unblocked can be preset. fix and current threshold I fix When the motor current I approaches the current threshold I... fix Or the voltage U is close to the voltage threshold U fix When the oil circuit is in a state of being unblocked or about to be unblocked, the controller 620 can determine that the current oil circuit is in a state of being unblocked or about to be unblocked, thereby controlling the motor to exit the on / off mode and restoring the supply of liquid from the hydraulic pump 410 to the chain 100 for lubrication or cooling.

[0082] In common working environments, 0.5≤N≤0.9 can be set to meet most working conditions of the chainsaw 10. Specifically, in some working conditions where the chainsaw 10 has stringent requirements for lubrication or cooling, 0.8≤N≤0.9 or 0.90≤N≤0.99 can be set to meet the stringent requirements for lubrication or cooling of the chainsaw 10.

[0083] In some embodiments, the controller 620 can control the motor to be in a running state within the conduction duration L3. Optionally, in common working environments, the conduction duration L3 can be set to a fixed value, where 2s ≤ L3 ≤ 15s, to meet most working conditions of the chainsaw 10. Alternatively, the conduction duration L3 can be set to be related to ΔI. fix or △U fix A linear relationship is maintained to meet lubrication or cooling requirements under different operating conditions. In one embodiment, the conduction duration L3 is related to the current change threshold ΔI. fix There is a negative correlation, that is, the threshold value of the change in current ΔI fix The larger the value, the smaller the conduction duration L set by the controller 620, and vice versa. An example is L3 = K1 * ΔI. fix+b1, where K1 and b1 are constants, and their values ​​differ under different operating conditions. In one embodiment, the conduction duration L3 is related to the voltage change threshold ΔU. fix There is a negative correlation, that is, the threshold voltage change ΔU fix The larger the value, the smaller the conduction duration L set by the controller 620, and vice versa. An example is L3 = K2 * ΔU. fix +b2, where K2 and b2 are constants, and the values ​​of K2 and b2 are different under different working conditions.

[0084] In some embodiments, the controller 620 can control the motor to switch between a start state and a stop state at a frequency F. Optionally, in common working environments, the switching frequency F can be set to a fixed value, where F ≤ 1Hz, to meet most working conditions of the chainsaw 10. Alternatively, the switching frequency F can be set to be related to ΔI. fix or △U fix A linear relationship is maintained to meet lubrication or cooling requirements under different operating conditions. In one embodiment, the switching frequency F is related to the current change threshold ΔI. fix There is a positive correlation, that is, the threshold value of the change in current ΔI fix The larger the value, the larger the on / off frequency F set by the controller 620, and vice versa. An example is F = K3 * ΔI. fix +b3, where K3 and b3 are constants, and their values ​​differ under different operating conditions. In one embodiment, the switching frequency F is related to the voltage change threshold ΔU. fix There is a positive correlation, that is, the voltage change threshold ΔU fix The larger the value, the larger the on / off frequency F set by the controller 620, and vice versa. An example is t = K4 * ΔU. fix +b4, where K4 and b4 are constants, and the values ​​of K4 and b4 are different under different working conditions.

[0085] like Figure 6 As shown, this application provides a control method for determining whether the hydraulic pump 410 of the chainsaw 10 is blocked, the steps of which are as follows:

[0086] S210. Obtain the amount or rate of change of the motor's electrical parameters within a preset detection time L2;

[0087] S220. When the change in the electrical parameters of the motor is greater than or equal to a preset threshold for the change in electrical parameters, or when the rate of change of the electrical parameters of the motor is greater than or equal to a preset threshold for the rate of change of electrical parameters, the pump is determined to be in a blocked state.

[0088] like Figure 7 As shown, this application provides a control method for releasing the blocked state of the chainsaw 10, the steps of which are as follows:

[0089] S310. Determine if the liquid pump 410 is blocked. If yes, control the motor to enter on / off mode and proceed to step S320. If no, control the motor to exit on / off mode. In on / off mode, the motor intermittently enters and exits the on / off state.

[0090] S320. Determine whether the value of the electrical parameter is within the preset range. If yes, control the motor to exit the on / off mode. If no, control the motor to remain in the on / off mode.

[0091] like Figure 8 As shown, this application provides another control method for unblocking the chainsaw 10, the steps of which are as follows:

[0092] S410: Determine if the liquid pump 410 is blocked. If yes, control the motor's electrical parameters to be lower than a preset electrical parameter threshold, and proceed to step S420. If no, control the motor to exit the on / off mode. In the on / off mode, the motor intermittently switches between on and off states.

[0093] S420. Determine whether the value of the electrical parameter is within the preset range. If yes, control the motor to exit the on / off mode. If no, control the motor to enter the on / off mode.

[0094] The above parameters, such as preset detection duration L2, conduction duration L3, switching frequency F, and current change threshold ΔI, are... fix and voltage change threshold ΔU fix When the oil circuit is not blocked, the voltage value U of the second motor 420 is... fix and current value I fix Empirical parameters such as N, K1, K2, K3, K4, b1, b2, b3, and b4 can be pre-stored in the memory 650 and read by the parameter reading module 660.

[0095] In some embodiments, when the chainsaw 10 is started, the hydraulic pump 410 continuously releases liquid to lubricate or cool the chain 100 until the chainsaw 10 is turned off. However, the chainsaw 10 does not require constant lubrication or cooling of the output tool during startup, and continuous release would waste the lubricating or cooling liquid. This application provides an embodiment that can reduce the consumption of lubricating or cooling liquid while ensuring good working performance of the chain 100.

[0096] In some embodiments, the controller 620 of the chainsaw 10 is configured to control the second motor 420 to cycle between starting and stopping: controlling the second motor 420 to start for a start duration L4 and then controlling the second motor 420 to stop for a stop duration L5.

[0097] Since the second motor 420 is used to drive the hydraulic pump 410 to release the liquid that lubricates or cools the chain 100, the volume or speed of the liquid released by the hydraulic pump 410 can be controlled by controlling the start-up duration L4, the shutdown duration L5, or the speed V2 of the second motor 420. Specifically, the controller 620 intermittently and cyclically starts and stops the second motor 420, thereby avoiding the continuous release of the liquid that lubricates or cools the chain 100 by the hydraulic pump 410, reducing the consumption of liquid, and also preventing the oil circuit from becoming blocked.

[0098] A longer start-up duration L4 results in better lubrication and cooling of chain 100, but also increases fluid consumption. Conversely, a shorter start-up duration L4 results in lower fluid consumption for lubrication and cooling, but worsens lubrication and cooling of chain 100. The applicant's experiments revealed that setting the start-up duration L4 to less than or equal to 5 seconds and greater than or equal to 1 second balances the performance requirements of chain 100 and fluid conservation under common operating conditions.

[0099] A shorter shutdown duration L5 results in better lubrication and cooling of chain 100, but also increases fluid consumption. Conversely, a longer shutdown duration L5 results in lower fluid consumption for lubrication and cooling, but worsens lubrication and cooling of chain 100. The applicant's experiments revealed that setting the shutdown duration L5 to be greater than or equal to 5 seconds and less than or equal to 9 seconds balances the performance requirements of chain 100 and fluid conservation under common operating conditions.

[0100] The applicant discovered through experiments that the shutdown duration L5 can be set to be greater than the startup duration L4, which can balance the needs of chain 100 for working performance and saving liquid consumption under common operating conditions.

[0101] In some embodiments, the speed and time at which the pump 410 releases the liquid to lubricate or cool the chain 100 are fixed, which cannot meet the lubrication or cooling requirements of the chainsaw 10 under different working conditions. This application provides an embodiment that can adapt to the lubrication or cooling requirements of the chainsaw 10 under different working conditions.

[0102] In some embodiments, the chainsaw 10 further includes a temperature detection module 610 for detecting the ambient temperature T0 of the chainsaw 10.

[0103] Optionally, the start-up duration L4 of the second motor 420 and the ambient temperature T0 of the chainsaw 10 can satisfy a linear or non-linear relationship, thereby releasing different amounts of lubricating or cooling liquid under different operating conditions. In one embodiment, the start-up duration L4 is negatively correlated with the ambient temperature T0; that is, the higher the ambient temperature T0, the shorter the start-up duration L4 of the second motor 420 set by the controller 620, and vice versa. An exemplary L4 = K5 * T0 + b5, where K5 and b5 are constants, and their values ​​differ under different operating conditions.

[0104] Optionally, the shutdown duration L5 of the second motor 420 and the ambient temperature T0 of the chainsaw 10 have a linear or non-linear relationship, thereby releasing different amounts of lubricating or cooling liquid under different operating conditions. In one embodiment, the shutdown duration L5 is positively correlated with the ambient temperature T0; that is, the higher the ambient temperature T0, the longer the shutdown duration L5 of the second motor 420 set by the controller 620, and vice versa. An exemplary L5 = K6 * T0 + b6, where K6 and b6 are constants, and their values ​​differ under different operating conditions.

[0105] In some embodiments, the chainsaw 10 further includes a speed detection module 630 for detecting the rotational speed V1 of the first motor 300.

[0106] Optionally, the start-up duration L4 of the second motor 420 and the rotational speed V1 of the first motor 300 have a linear or non-linear relationship, thereby releasing different amounts of lubricating or cooling liquid under different operating conditions. In one embodiment, the start-up duration L4 is positively correlated with the rotational speed V1 of the first motor 300; that is, the faster the rotational speed V1 of the first motor 300, the longer the start-up duration L4 of the second motor 420 set by the controller 620, and vice versa. An exemplary L4 = K7 * V1 + b7, where K7 and b7 are constants, and their values ​​differ under different operating conditions.

[0107] Optionally, the shutdown duration L5 of the second motor 420 and the rotational speed V1 of the first motor (300 rpm) have a linear or non-linear relationship, thereby releasing different amounts of lubricating or cooling liquid under different operating conditions. In one embodiment, the shutdown duration L5 is negatively correlated with the rotational speed V1 of the first motor; that is, the faster the rotational speed V1 of the first motor (300 rpm), the shorter the shutdown duration L5 of the second motor 420 set by the controller 620, and vice versa. An exemplary L5 = K8 * T0 + b8, where K8 and b8 are constants, and their values ​​differ under different operating conditions.

[0108] In some embodiments, the speed detection module 630 can also be used to detect the rotational speed V2 of the second motor 420, wherein the controller 620 is configured to control the second motor 420 to rotate at a speed V2 based on the rotational speed V1 of the first motor 300, wherein the rotational speed V1 of the first motor 300 and the rotational speed V2 of the second motor 420 satisfy a linear or nonlinear relationship. In one embodiment, the rotational speed V2 of the second motor 420 is positively correlated with the rotational speed V1 of the first motor 300, that is, the higher the rotational speed V1 of the first motor 300, the faster the rotational speed V2 of the second motor 420 set by the controller 620, and vice versa. An exemplary V2 = K9 * V1 + b9, where K9 and b9 are constants, and the values ​​of K9 and b9 differ under different operating conditions.

[0109] In some embodiments, the rotational speed V2 of the second motor 420 is positively correlated with the linear speed V3 of the chain 100. That is, the faster the linear speed V3 of the chain 100, the faster the rotational speed V2 of the second motor 420 set by the controller 620, and vice versa. In one embodiment, the optimal amount of lubricating or cooling fluid per unit length of the chain 100 is C0. For example, the rotational speed V2 of the second motor 420 satisfies V2 = K0 * V3 * C0 + b0, where K0, C0, and b0 are constants, and their values ​​differ under different operating conditions. The linear speed V3 of the chain 100 is linearly positively correlated with the rotational speed V1 of the first motor 300. That is, the faster the rotational speed V1 of the first motor 300, the faster the linear speed V3 of the chain 100, and vice versa.

[0110] In some embodiments, the chainsaw 10 can be a chainsaw 10, the chain 100 can be a chain 100, and the first motor 300 drives the chain 100 to rotate via a sprocket. The pitch of the chain 100 can be S0, the number of teeth on the sprocket can be N0, and the rotational speed of the sprocket can be V4, then the linear velocity of the chain 100 is... Then the controller 620 can control the speed V2 of the second motor 420 to meet the requirements. This allows for higher lubrication or cooling efficiency with less fluid consumption.

[0111] The above parameters, such as the optimal amount of lubricating or cooling liquid C0 per unit length of chain 100, the pitch S0 of chain 100, the number of teeth N0 of sprocket, and empirical parameters such as K5, K6, K7, K8, K9, b5, b6, b7, b8, and b9, can be pre-stored in the memory 650 and read by the parameter reading module 660.

[0112] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. A chain saw, comprising: a chain for performing a cutting operation; a liquid pump assembly including a liquid pump for supplying a liquid for lubricating or cooling the chain, and a motor for driving the liquid pump to operate; a controller electrically connected to at least the liquid pump assembly; characterized in that the controller is configured to: control the liquid pump assembly to enter a throttling mode of reducing the amount of liquid supplied when the liquid pump is in a clogging state; control the liquid pump assembly to exit the throttling mode when the liquid pump exits the clogging state.

2. The chain saw of claim 1, wherein the controller is configured to: control the motor to be in an on-off mode to make the liquid pump assembly enter the throttling mode when the liquid pump is in the clogging state; control the motor to exit the on-off mode when the liquid pump exits the clogging state; wherein in the on-off mode, the motor is intermittently in an activated state and a deactivated state.

3. The chain saw of claim 2, wherein the motor includes: a first motor for driving the chain to operate; a second motor for driving the liquid pump to operate; wherein the controller is configured to: control the second motor to be in an on-off mode when the liquid pump is in the clogging state; control the second motor to exit the on-off mode when the liquid pump exits the clogging state; wherein in the on-off mode, the second motor is intermittently in an activated state and a deactivated state.

4. The chain saw of claim 1, wherein the controller is configured to: control the motor to be in a low-power mode when the liquid pump is in the clogging state; control the motor to exit the low-power mode when the liquid pump exits the clogging state; wherein in the low-power mode, a value of an electrical parameter of the motor is lower than a preset electrical parameter threshold.

5. The chain saw of claim 4, wherein the motor includes: a first motor for driving the chain to operate; a second motor for driving the liquid pump to operate; wherein the controller is configured to: control the second motor to be in a low-power mode when the liquid pump is in the clogging state; control the second motor to exit the low-power mode when the liquid pump exits the clogging state; wherein in the low-power mode, a value of an electrical parameter of the second motor is lower than a preset electrical parameter threshold.

6. The chain saw according to any of claims 1 to 5, characterized in that the chain saw further comprises a circuit detection module for detecting the electrical parameter of the motor.

7. The chain saw of claim 6, wherein the controller is configured to: obtain a variation amount or a variation rate of the electrical parameter within a preset detection duration; determine that the liquid pump is in the clogging state when the variation amount of the electrical parameter is greater than or equal to a variation amount threshold of the electrical parameter, or when the variation rate of the electrical parameter is greater than or equal to a variation rate threshold of the electrical parameter.

8. The chain saw of claim 7, wherein the preset detection duration is greater than or equal to 20 milliseconds and less than or equal to 100 milliseconds.

9. The chain saw of claim 7, wherein, the electrical parameter includes a value of a voltage and / or a value of a current.

10. The chain saw of claim 7, wherein, the variation amount threshold of the current is greater than or equal to 450 milliamps.

11. The chain saw of claim 7, wherein the variation amount threshold of the voltage is greater than or equal to 1 volt.

12. The chain saw of claim 7, wherein, the variation rate threshold of the current is greater than or equal to 4.5 milliamps per millisecond.

13. The chain saw of claim 7, wherein, the variation rate threshold of the voltage is greater than or equal to 0.01 volts per millisecond.

14. The chain saw of claim 6, wherein, the controller is configured to: determine that the liquid pump exits the clogging state when the value of the electrical parameter of the motor is within a preset range.

15. The chain saw of claim 14, wherein, the controller is configured to: The value of the electrical parameter is within the preset range when the value of the electrical parameter equals to N times of a preset electrical parameter threshold, wherein 0.5≤N≤0.

9.

16. A method for resolving a clogging state of a chain saw, the chain saw comprising: a chain for performing a cutting operation; a liquid pump assembly including a liquid pump for supplying a liquid for lubricating or cooling the chain, and a motor for driving the liquid pump to operate; the method comprising the steps of: controlling the liquid pump assembly to enter a throttling mode of reducing the amount of the liquid supplied, when the liquid pump is in the clogging state; controlling the liquid pump assembly to exit the throttling mode, when the liquid pump exits the clogging state.

17. The method of unblocking a chain saw according to claim 16, characterized in that the motor comprising: a first motor for driving the chain to operate; a second motor for driving the liquid pump to operate; the method comprising the steps of: controlling the second motor to be in an on-off mode or a low-power mode to make the liquid pump assembly enter the throttling mode, when the liquid pump is in the clogging state; controlling the second motor to exit the on-off mode or the low-power mode, when the liquid pump exits the clogging state; in the on-off mode, the second motor is intermittently in an activated state and a deactivated state; in the low-power mode, a value of an electrical parameter of the second motor is lower than a preset electrical parameter threshold.

18. A method for judging a clogging state of a chain saw, the chain saw comprising: a chain for performing a cutting operation; a liquid pump assembly including a liquid pump for supplying a liquid for lubricating or cooling the chain, and a motor for driving the liquid pump to operate; a circuit detection module for detecting an electrical parameter of the motor; the method comprising the steps of: obtaining a variation amount or a variation rate of the electrical parameter of the motor within a preset detection duration; judging that the liquid pump is in the clogging state, when the variation amount of the electrical parameter is greater than or equal to a variation amount threshold of the electrical parameter, or when the variation rate of the electrical parameter is greater than or equal to a variation rate threshold of the electrical parameter; judging that the liquid pump exits the clogging state, when a value of the electrical parameter of the motor is within a preset range; controlling the liquid pump assembly to enter a throttling mode of reducing the amount of the liquid supplied, when the liquid pump is in the clogging state.

19. A chain saw comprising: a chain for performing a cutting operation; a liquid pump assembly including a liquid pump for supplying a liquid for lubricating or cooling the chain, and a motor for driving the liquid pump to operate; a controller electrically connected with at least the motor; the liquid pump assembly having a throttling mode of reducing the amount of the liquid supplied; the controller being configured to: control the liquid pump assembly to enter the throttling mode, when the liquid pump is in a clogging state; in the throttling mode, the controller is configured to control the motor to cyclically activate and deactivate: to activate the motor for an on duration, and then to deactivate the motor for an off duration.

20. The chain saw of claim 19, wherein, the on duration is less than the off duration.

21. The chain saw of claim 19, wherein, the on duration is less than or equal to 5 seconds and greater than or equal to 1 second.

22. The chain saw according to any of claims 19 to 21, characterized in that the off duration is greater than or equal to 5 seconds and less than or equal to 9 seconds.

23. The chain saw of claim 19, wherein, The chain saw further comprises a temperature detection module configured to detect an ambient temperature of the chain saw.

24. The chain saw of claim 23, wherein, The controller is configured to set the on duration of the motor according to the value of the ambient temperature.

25. The chain saw of claim 19, wherein, The motor comprises: a first motor configured to drive the chain saw operation; a second motor configured to drive the liquid pump operation.

26. The chain saw of claim 25, wherein, The chain saw further comprises a speed detection module configured to detect a rotational speed of the first motor.

27. The chain saw of claim 26, wherein, The controller is configured to set the on duration of the second motor according to the rotational speed of the first motor.

28. The chain saw of claim 26, wherein, The speed detection module can be further configured to detect a rotational speed of the second motor, and the controller is configured to set the rotational speed of the second motor according to the rotational speed of the first motor.

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