Power tool and start control method thereof

Abstract

The application discloses an electric tool and a starting control method thereof. The electric tool comprises a driving structure, a motor, a driving circuit and a controller. The motor rotates to drive the driving structure to operate. The driving circuit is electrically connected with the motor to drive the motor to rotate. The controller is electrically connected with the driving circuit and is configured to output a first control signal to control the motor to drive the driving structure to operate in a first operating mode for a preset time period when a starting instruction is received, and output a second control signal to control the motor to drive the driving structure to operate in a second operating mode to a preset state after the preset time period, wherein the first operating mode and the second operating mode are two opposite operating modes. According to the application, the controller controls the motor to reverse for a preset time period before the electric tool is formally started, so that the speed-up distance of the driving structure before normal starting is obtained, and then the normal starting stage is started based on the distance, thereby increasing the load starting capacity during normal starting.

Description

TECHNICAL FIELD

[0001] The present application relates to an electric power tool, in particular to an electric power tool and a starting control method thereof. BACKGROUND

[0002] In many electric power tools, especially small gear transmission structure electric power tools, there is usually a weak problem of load starting ability. In order to enhance the load starting ability of the gear transmission structure, the general way is to increase the number of gears, increase the size of the gear, replace the type of gear, etc.

[0003] However, by changing the hardware entity to increase the load starting ability of the gear transmission structure, the hardware cost is increased, and at the same time, the weight of the electric power tool is also increased or its shape is changed, thereby reducing the user experience. SUMMARY

[0004] In order to solve the problems of the prior art, the purpose of the present application is to provide an electric power tool and a starting control method thereof, which can improve the load starting ability of the electric power tool without changing the hardware structure of the electric power tool.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solution:

[0006] An electric power tool, comprising:

[0007] a driving structure;

[0008] a motor, the motor rotates to drive the driving structure to run;

[0009] a driving circuit, electrically connected with the motor to make the motor rotate;

[0010] a controller, electrically connected with the driving circuit,

[0011] the controller is configured to: when receiving a starting instruction, output a first control signal to control the motor to drive the driving structure to run in a first running mode for a preset time period;

[0012] after the preset time period, output a second control signal to control the motor to drive the driving structure to run in a second running mode until a preset state,

[0013] wherein the first running mode and the second running mode are two opposite running modes.

[0014] Further, the driving structure is a transmission structure.

[0015] Further, the transmission structure comprises a driving gear and a driven gear, and the driving gear is configured to:

[0016] The first control signal is outputted to control the motor to drive the driving gear to rotate in a first rotating direction for a preset time period.

[0017] After the preset time period, the controller outputs a second control signal to control the motor to drive the driving gear to rotate in a second rotating direction to a preset state,

[0018] The first rotating direction and the second rotating direction are opposite directions.

[0019] Further, the driving gear is configured to:

[0020] The driving gear rotates a speed-up distance based on the preset time period under the driving of the first control signal.

[0021] Further, the speed-up distance ranges from greater than or equal to zero to less than or equal to a tooth spacing between two teeth in the gear.

[0022] Further, the controller is configured to:

[0023] The controller outputs a first control signal with adjustable duty cycle to control the motor for the preset time period.

[0024] Further, the controller is configured to:

[0025] After the driving gear operates to the preset state, it is determined whether the motor is stalled according to any one or more parameters of a rotating speed of the motor or a current or voltage loaded on the motor.

[0026] When the controller determines that the motor is stalled, a third control signal is outputted to control the power tool to stop operating.

[0027] Upon receiving a start instruction, a first control signal is outputted to control the motor to drive the driving gear to operate in a first operating mode for a preset time period.

[0028] After the preset time period, a second control signal is outputted to control the motor to drive the driving gear to operate in a second operating mode to a preset state.

[0029] A start control method for a power tool, comprising:

[0030] Upon receiving a start instruction, a first control signal is outputted by the controller to control the motor to drive a driving structure in the power tool to operate in a first operating mode for a preset time period.

[0031] After the preset time period, a second control signal is outputted by the controller to control the motor to drive the driving structure to operate in a second operating mode to a preset state,

[0032] The first operating mode and the second operating mode are two opposite operating modes.

[0033] Further, the driving structure is a transmission structure.

[0034] Further, the transmission structure comprises at least a driving gear and a driven gear, and the method further comprises:

[0035] In a preset time period, the controller outputs a first control signal to control the motor to drive the driving gear to rotate in a first rotation direction;

[0036] After the preset time period, the controller outputs a second control signal to control the motor to drive the driving gear to rotate in a second rotation direction to a preset state,

[0037] Wherein, the first rotation direction and the second rotation direction are two opposite directions. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a structural schematic diagram of an electric tool provided by an embodiment of the present application;

[0039] Figure 2 is a flowchart of an electric tool starting control method provided by an embodiment of the present application;

[0040] Figure 3 is a flowchart of another electric tool starting control method provided by an embodiment of the present application;

[0041] Figure 4 is a schematic diagram of the relative state of the driving gear before the electric tool starts to the normal starting gear provided by an embodiment of the present application;

[0042] Figures 5a-5b is a schematic diagram of the speed-up distance and the gear spacing provided by an embodiment of the present application;

[0043] Figures 6a-6b is a schematic diagram of two close meshing states provided by an embodiment of the present application. DETAILED DESCRIPTION

[0044] The present application will be described in detail below in conjunction with the drawings and specific embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, and not to limit the present application. In addition, it should be noted that, in order to facilitate the description, only the parts related to the present application are shown in the drawings, not all the structures.

[0045] It should be noted that the control starting method in the present application is mainly applied to electric tools with gear transmission structure, such as saw tools, drill tools, etc. The first, second and third involved in the present application do not represent the size or order of the number, but only for the naming needs.

[0046] In the first embodiment of the present application, a kind of as Figure 1The electric tool 10 shown includes a controller 101, a driving circuit 102, a motor 103 and a transmission structure 104.

[0047] In a specific implementation, the motor 103 rotates to drive the transmission structure 104 to operate.

[0048] The driving circuit 102 is electrically connected with the motor 103 to drive the motor 103 to rotate.

[0049] The controller 101 is electrically connected with the driving circuit 102 and is configured to, when receiving a starting instruction, output a first control signal to control the motor to drive the transmission structure 104 to operate in a first operating mode for a preset time period.

[0050] In a specific implementation, after the starting trigger of the electric tool is pressed by an operator, the controller 101 can receive the starting instruction of the electric tool 10, and then the controller 101 can output the first control signal to control the electric tool to operate in the first operating mode for a preset time period. In some embodiments, the preset time period ranges from 5 ms to 10 ms. The preset time period can be a fixed time period written in advance, such as 5 ms, 10 ms or other smaller time periods. The preset time period can also be updated by an external device, such as a mobile terminal such as a mobile phone. It should be noted that the electric tool 10 is not actually started within the above-mentioned preset time period, and it can be understood that the rotation of the motor within this time period is a pre-start before the normal start of the electric tool. The first operating mode of the driving structure in the preset time period is opposite to the second operating mode after this time period. For example, when the chain saw is working normally, the driving gear rotates clockwise, and when the chain saw is started, the driving gear rotates counterclockwise for a time period (such as 5 ms) for pre-starting, and then rotates clockwise to a certain state (such as a certain rotating speed), so that the electric tool can work normally. The counterclockwise rotation of the driving gear is the first operating mode, and the clockwise rotation is the second operating mode.

[0051] By pre-starting for a preset time period, the electric tool 10 can obtain a speed-up parameter that is beneficial to enhancing the starting force. This parameter will increase the driving force of the driving structure in the subsequent normal starting stage, thereby improving the load starting force of the electric tool. For example, in the 5 ms pre-starting time period of the chain saw, the central angle of the counterclockwise rotation of the driving gear is Therefore, the arc length can be calculated according to the formula The arc length L turned by the driving gear in the preset time period is calculated, and in some embodiments, the arc length L turned by the driving gear in the preset time period can be defined as the acceleration parameter. It can be understood that in the case of starting the chain saw, the driving gear rotates clockwise through the arc length L after the preset time period 5 ms, and in this process, the driving gear is in an idle state and does not drive the driven gear to rotate. In this process, the driving gear obtains a larger starting force, and then in the process after the arc length L is turned, the starting ability of the chain saw under load is enhanced based on the larger starting force.

[0052] In some embodiments, the acceleration parameter is defined as an arc length, and in other possible embodiments, the acceleration parameter can be any parameter obtained for enhancing the starting ability under load.

[0053] In some embodiments, the duty cycle of the first control signal is adjustable, and is generally less than 8%.

[0054] Further, the controller 101 outputs a second control signal to control the motor 103 to drive the transmission structure 104 to operate in a second operating mode to a preset state after the preset time period.

[0055] It can be understood that the preset state can be a state in which the driving structure reaches a certain rotating speed or reaches a certain working voltage or current, and in this state, the power tool 10 can work normally, and can be in an idle state or under load. After the driving structure reaches the preset state, the power tool 10 is started and can work normally.

[0056] In an alternative implementation, in the normal operation of the power tool 10, if the controller 101 detects that the rotating speed of the motor 103 is lower than a given threshold or the back electromotive force does not commutate, it is determined that the tool is stalled, and the controller 101 outputs a third control signal to control the tool to stop. When the user releases the trigger and presses it again, i.e., the user restarts the tool, the controller 101 can receive a starting instruction again, and accordingly outputs a first control signal to control the power tool 10 to pre-start as described above, and outputs a second control signal to control the driving structure to operate in a second operating mode to the preset state after the preset time period.

[0057] It can be understood that in addition to the above-mentioned structural components, the power tool 10 also includes other accessories, such as a battery pack, a housing, a drill bit, a handle, etc. Since the other accessories do not directly participate in the process of starting control of the power tool, they are not described in detail in the present application.

[0058] In the embodiment of the application, before the electric tool is formally started, the controller controls the motor to reverse for a preset time period, so as to obtain a speed-up parameter of the driving structure before normal starting, and then the normal starting stage is started based on the parameter, thereby increasing the load starting capability during normal starting.

[0059] Please refer to Figure 2 In the second embodiment of the application, the electric tool starting control method can at least include the following steps:

[0060] S101, when receiving a starting instruction, the controller outputs a first control signal to control the motor to drive the driving structure in the electric tool to operate in a first operation mode for a preset time period.

[0061] In some embodiments, the driving structure can be a transmission structure, which can include a driving gear and a driven gear. In the preset time period, the first control signal output by the controller controls the motor to drive the driving gear to rotate in a first rotation direction, wherein the duty cycle of the first control signal is adjustable, and the value is generally below 8%.

[0062] S102, after the preset time period, the controller outputs a second control signal to control the motor to drive the driving structure to operate in a second operation mode until a preset state is reached.

[0063] In an embodiment, the second control signal output by the controller controls the motor to drive the driving gear to rotate in a second rotation direction; wherein the first rotation direction and the second rotation direction are two opposite directions.

[0064] In some embodiments, the driving gear rotates a speed-up distance L under the drive of the first control signal in the preset time period, L is greater than or equal to zero and less than or equal to the tooth spacing between two teeth in the gear.

[0065] It can be understood that the above-mentioned preset state can be a state in which the driving structure reaches a certain rotational speed or reaches a certain working voltage or current, etc., in which state the electric tool 10 can be under load or under load. After the driving structure reaches the preset state, the electric tool 10 completes the starting and can perform normal work.

[0066] In some embodiments, during normal operation of the power tool, the controller can determine whether the motor is locked based on any one or more of the motor speed or the current or voltage applied to the motor, and if locked, output a third control signal to control the power tool to stop running; and only when the power tool is started again, i.e. when the start instruction is received again, the controller outputs the first control signal to control the motor to drive the drive gear to run in the first running mode for a preset period of time, and after the preset period of time, the second control signal is output to control the motor to drive the drive gear to run in the second running mode to the preset state.

[0067] It should be noted that the start control process of the start control method for the power tool in the present embodiment can refer to the description of the power tool and its start process in Embodiment I above, which will not be repeated here.

[0068] Please refer to Figure 3 In the third embodiment of the present application, the start control method for the power tool can at least include the following steps:

[0069] S201, upon receiving a start instruction, the controller outputs a first control signal to control the motor to drive the drive gear to rotate in a first rotation direction.

[0070] S202, after a preset period of time, the controller outputs a second control signal to control the motor to drive the drive gear to rotate in a second rotation direction to a preset state.

[0071] In the present embodiment, the drive structure in the power tool mainly refers to the transmission structure with gears. The following will illustrate the start control process of the present application by the process of load start of the power tool with gears:

[0072] Figure 4 The relative states of the drive gear and the driven gear of the power tool in three stages are shown, wherein the three stages include pre-start 10, pre-start 20 and normal start 30.

[0073] First of all, it should be noted that in Figure 4 In the example shown, counterclockwise rotation of the drive gear 1 is the second rotation direction described above, and clockwise rotation is the first rotation direction described above. In particular, in the pre-start 10 stage, the drive gear 1 and the driven gear 2 are closely meshed, and if the drive gear 1 is immediately reversed, the starting ability of the tool will be poor. Further, in the pre-start 20 stage, the controller outputs a first control signal with adjustable duty cycle to control the drive gear 1 to rotate in the first rotation direction, i.e. clockwise, for a preset period of time (e.g. 5ms), and the drive gear 1 and the driven gear 2 are pulled apart by a certain distance, which is the arc length L on the drive gear 1. Figure 5aThe thick arc length shown is also referred to as the acceleration distance obtained by the drive gear 1 rotating within a preset time period. It should be noted that in the initial state, i.e., the first 10 stages of startup, regardless of whether the drive gear 1 and driven gear 2 are tightly meshed, the impact of the drive gear 1 rotating clockwise for a preset time period during the pre-start stage (stage 20) on the load of the power tool is negligible. Therefore, regardless of whether the drive gear 1 and driven gear 2 are tightly meshed during the first 10 stages of startup, the controller must first output a first control signal to control the drive gear 1 to rotate in the first rotation direction for a preset time period for pre-start. Furthermore, in the normal startup stage (stage 30), the drive gear 1 rotates counterclockwise to a preset state based on the acceleration distance L, i.e., the second rotation direction, i.e., counterclockwise. This state ensures that the speed, voltage, or current of the drive gear meets the requirements for normal operation of the power tool. In this state, the power tool can be unloaded or loaded.

[0074] It is understandable that the acceleration distance L mentioned above can be zero at its minimum and no more than the tooth spacing between two teeth in the gear. Right now Figure 5b The thick line shows the arc length.

[0075] In one state, the acceleration distance L can be as low as zero, for example, when the driving gear 1 and the driven gear 2... Figure 6a In the state shown, the gears are tightly engaged. If the drive gear 1 does not rotate within a preset time period or the preset time period is too short to generate a rotational distance, the acceleration distance L when the drive gear 1 starts rotating in the second rotational direction is zero. In another state, the acceleration distance L does not exceed the tooth spacing between two teeth in the gear. At the point of maximum acceleration distance, drive gear 1 and driven gear 2... Figure 6b The state shown is a tight mesh (this state can be the initial state of the gear before the power tool is started, or the state after the drive gear 1 has rotated within a preset time period). At this time, the acceleration distance L when the drive gear 1 rotates in the second rotation direction is... Of course, after the preset time period, if the driving gear 1 and the driven gear 2 are in a state between the aforementioned close meshing state, the acceleration distance L will be greater than zero and less than... Yes. Additionally, because different power tools use different types of gears, the corresponding tooth pitch also varies, but the tooth pitch within the same power tool... It is a fixed value.

[0076] In this embodiment of the invention, due to the existence of the aforementioned acceleration distance L, the drive gear can generate a stronger starting force based on the acceleration distance L during normal startup, thereby enhancing the load-bearing starting capability of the gear transmission.

[0077] It should be noted that the duty cycle of the first control signal is adjustable, and is generally less than 8%. Through the first control signal with adjustable duty cycle, the reverse pre-starting requirements of different power tools in different starting scenarios are met, and the flexibility of pre-starting control is increased.

[0078] In an optional implementation, in the process of starting and normal operation of the power tool, if the controller detects that the rotating speed of the motor is lower than a given threshold or the back electromotive force is not commutated, it is determined that the tool is stalled, and the controller outputs a third control signal to control the tool to stop. When the user releases the trigger and then presses it again, i.e., the user restarts the tool, the controller receives an opening instruction again, can output the first control signal again for pre-starting as described above, and output the second control information to control the driving gear to rotate in the second rotating direction to a preset state after a preset time period.

[0079] In the embodiment of the present application, before the power tool is formally started, the controller controls the motor to reverse for a preset time period, so as to obtain the acceleration distance of the driving structure before normal starting, and then start in the normal starting phase based on the distance, thereby increasing the load starting ability in the normal starting.

[0080] It should be noted that the above are only preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments herein, and those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. An electric tool, include: A drive structure, the drive structure including a drive gear and a driven gear; An electric motor, which rotates to drive the drive structure. A drive circuit is electrically connected to the motor to make the motor rotate; The controller is electrically connected to the drive circuit. The controller is characterized in that, upon receiving a start command, it outputs a first control signal to control the motor to drive the drive gear to rotate in a first rotation direction for a preset time period. After the preset time period, a second control signal is output to control the motor to drive the drive gear to rotate in a second rotation direction to a preset state, wherein the second rotation direction is opposite to the first rotation direction; Driven by the first control signal, the drive gear rotates an acceleration distance based on the preset time period, and the acceleration distance is greater than or equal to zero and less than or equal to the tooth spacing between two teeth in the gear.

2. The power tool according to claim 1, characterized in that, The driving structure is a transmission structure.

3. The power tool according to claim 1, characterized in that, The controller is configured to output a first control signal with an adjustable duty cycle to control the motor during the preset time period.

4. The power tool according to claim 1, characterized in that, The controller is configured to: After the drive gear runs to the preset state, it is determined whether the motor is stalled based on one or more parameters, such as the motor speed or the current or voltage applied to the motor. When it is determined that the motor is stalled, a third control signal is output to control the power tool to stop running; Upon receiving the start command, the first control signal is output to control the motor to drive the drive gear to run in the first rotation direction for the preset time period; After the preset time period, the second control signal is output to control the motor to drive the drive gear to run in the second rotation direction to the preset state.

5. A starting control method for power tools, characterized in that, The method includes: Upon receiving a start command, the controller outputs a first control signal to control the motor to drive the drive gear in the drive structure of the power tool to rotate in a first rotation direction for a preset time period; wherein, the drive structure includes the drive gear and the driven gear; After the preset time period, the controller outputs a second control signal to control the motor to drive the drive gear to rotate in a second rotation direction to a preset state, wherein the second rotation direction is opposite to the first rotation direction; Driven by the first control signal, the drive gear rotates an acceleration distance based on the preset time period, and the acceleration distance is greater than or equal to zero and less than or equal to the tooth spacing between two teeth in the gear.

6. The control method according to claim 5, characterized in that, The driving structure is a transmission structure.

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