Motor control module and power tool comprising a motor control module

Abstract

The present application relates to a motor control module (100) comprising a motor (110), a motor switch (120), and a motor controller (130) configured to execute an automatic control logic or a real-time control logic in response to actuation of the motor switch (120), in the automatic control logic the output rotational speed of the motor (110) varies from 0 to a preset threshold rotational speed (Npre) and continues at the preset threshold rotational speed for a preset time period (Tpre) and then varies to a final steady rotational speed, in the real-time control logic continues at the preset threshold rotational speed for the preset time period when the real-time rotational speed of the motor (110) reaches the preset threshold rotational speed, wherein the preset threshold rotational speed is 1 / 6-2 / 3 of the no-load rated rotational speed (NR) of the motor and the preset time period (Tpre) is 0.2s-3s. The present application also relates to a power tool comprising the module.

Description

TECHNICAL FIELD

[0001] The present application relates to a motor control module for a power tool and a power tool comprising the motor control module, in particular a power tool outputting a reciprocating linear motion (percussion or hammering motion). BACKGROUND

[0002] Power tools outputting a reciprocating linear motion, such as electric hammers or hammer drills, are common in daily life. Such power tools generally comprise a driving portion containing a motor, a tubular body (or hammer tube) internally housing a percussion device, and a tool holder device for holding a tool (e.g. drill bit) of the power tool.

[0003] During operation, when the motor is started by actuating the motor switch, the rotational motion of the motor output shaft is transmitted to the percussion device reciprocating within the hammer tube via a transmission conversion structure, such as a swing bearing, which in turn drives the tool of the power tool to reciprocate linearly. The percussion device of the power tool has an unloaded position, in which it is not driven by the motor (decoupled from the motor) and thus no percussion force is generated, and a loaded position, in which it is coupled to the motor and driven to generate a percussion force, and is capable of reciprocating between the two positions.

[0004] Generally, for safety and tool service life extension considerations, it is desirable that the percussion device returns to and stays in the unloaded position when the power tool is stopped after operation. However, if for some reason, such as a malfunction or other human factors, the percussion device does not return to the unloaded position correctly when the power tool is stopped, but stays in the loaded position coupled to the motor. Then when the power tool is started next time, the motor outputs a high rotational speed in a short time and generates a percussion force on the percussion device, which on one hand causes a waste of energy and ineffective percussion action (hammering without load), and on the other hand can cause a safety accident.

[0005] The safety accident includes the high-speed flying or bouncing out of an inappropriate tool. It is known that power tools are usually equipped with drill bits of different shank configurations (shapes and / or sizes) to achieve different functions. If a worker installs a drill bit with a smaller shank size in the power tool but does not clamp or lock it firmly, or the worker may install a drill bit with a shank size too small to be allowed to be used in the power tool due to a mistake, then during the start of the power tool, if the motor outputs a high rotational speed rapidly to make the power tool generate a large amount of energy and the percussion device generates a large percussion force when the percussion device is in the loaded position, the drill bit will suddenly and rapidly "hit" or "bounce" out of the clamping device of the power tool. In this case, the drill bit is ejected at a high speed and with a high energy, which can cause damage to the surrounding personnel or objects and trigger a safety accident. SUMMARY

[0006] It is an object of the present application to solve at least one of the above technical problems.

[0007] To this end, in a first aspect of the present application, there is provided a motor control module for an electric power tool configured for outputting at least a reciprocating linear motion, the motor control module comprising: a motor; a motor switch for actuating the motor, the motor switch having a neutral gear position with a gear setting speed of zero and at least one on gear position, each of the at least one on gear position having a respective gear setting speed; and a motor controller configured to execute an automatic control logic comprising: automatically controlling the motor to vary its output speed from 0 to a preset threshold speed and to maintain at the preset threshold speed for a preset time period, then to vary from the preset threshold speed to the gear setting speed corresponding to a target on gear position, when the motor switch is actuated from the neutral gear position to the target on gear position, wherein the preset threshold speed is 1 / 6-2 / 3 of the motor’s no-load rated speed and the preset time period is 0.2s-3s.

[0008] In a second aspect of the present application, there is provided a motor control module for an electric power tool configured for outputting a reciprocating linear motion, the motor control module comprising: a motor; a motor switch for actuating the motor, the motor switch having a neutral gear position with a gear setting speed of zero and a plurality of on gear positions, each of the plurality of on gear positions having a respective gear setting speed; and a motor controller configured to control the motor to execute a real-time control logic based on a real-time measured motor speed, the real-time control logic comprising: varying the motor’s output speed from a gear setting speed corresponding to a first on gear position with a gear setting speed less than a preset threshold speed to a gear setting speed corresponding to a target on gear position with a gear setting speed greater than or equal to the preset threshold speed, and during this variation, executing a maintenance at the preset threshold speed for a preset time period when the real-time measured motor speed reaches the preset threshold speed, when the motor switch is actuated from the first on gear position to the target on gear position, wherein the preset threshold speed is 1 / 6-2 / 3 of the motor’s no-load rated speed and the preset time period is 0.2s-3s.

[0009] In a third aspect of the present application, a motor control module for a power tool configured for outputting a reciprocating linear motion is provided, the motor control module comprising: a motor; a motor switch for actuating the motor, the motor switch having a closed gear position with a gear set speed of zero and at least one open gear position, each of the at least one open gear position having a respective gear set speed; a mode selector configured for alternative selection between a first control mode of controlling an output speed of the motor independently of a real-time speed of the motor and a second control mode of controlling the output speed of the motor in dependence of the real-time speed of the motor; and a motor controller configured to execute an automatic control logic in the first control mode and a real-time control logic in the second control mode, wherein the automatic control logic comprises: automatically controlling the motor to change its output speed to a preset threshold speed and to maintain at the preset threshold speed for a preset time period when the motor switch is actuated from the closed gear position to a target open gear position of the at least one open gear position, and then change from the preset threshold speed to the gear set speed corresponding to the target open gear position, wherein the preset threshold speed is 1 / 6-2 / 3 of a no-load rated speed of the motor and the preset time period is 0.2s-3s; wherein the real-time control logic comprises: the at least one open gear position comprises a plurality of open gear positions, when the motor switch is actuated from a first gear position with a gear set speed less than the preset threshold speed to a target open gear position of the plurality of open gear positions with a gear set speed greater than the preset threshold speed, changing the output speed of the motor from the gear set speed corresponding to the first gear position to the gear set speed corresponding to the target open gear position, and during the changing, performing maintaining at the preset threshold speed for a preset time period when the real-time measured motor speed reaches the preset threshold speed, wherein the preset threshold speed is 1 / 6-2 / 3 of a no-load rated speed of the motor and the preset time period is 0.2s-3s.

[0010] In a fourth aspect of the present application, a power tool is provided, comprising: the above motor control module; a tubular body defining an inner bore in which an impact device is housed; and a chucking device comprising a chucking body having a tool receiving bore adapted to receive a shank of a tool of the power tool, wherein during operation of the power tool, the motor of the motor control module drives the impact device, and the impact device in turn drives the tool to perform a reciprocating linear motion, the impact device having an unloaded position of decoupling from the motor and a loaded position of coupling with the motor to generate an impact force.

[0011] The electric tool using the motor control module of the application, when the motor switch of the motor control module is actuated to start the motor in the starting process of the electric tool operation, the output rotating speed of the motor rises from 0 to a preset threshold rotating speed in a first time period and keeps at the preset threshold rotating speed for a preset time period, and then changes (rises or falls) to a final stable rotating speed. Wherein, the preset threshold rotating speed is 1 / 6-2 / 3 of the no-load rated rotating speed of the motor, and the preset time period is 0.2s-3s.

[0012] The setting of the preset threshold rotating speed and the preset time period in the motor starting process makes that: in this time period, the impact force generated by the operation of the motor on the impact device which may be in the load position (not correctly returned to the no-load position) as described above is enough to move it to the no-load position. This movement process can on the one hand ensure that the drill bit which is not correctly locked or the drill bit which is incorrectly installed with too small size is timely bounced out of the electric tool at a relatively low speed and a relatively low energy, or is only shaken and not bounced out, avoiding the safety accidents caused thereby; on the other hand, it also ensures that the impact device will be kept in the no-load position during or after the above-mentioned preset time period, before reaching the final stable rotating speed (such as the higher no-load rated rotating speed), so as to ensure that the impact device (hammer drill) will not have impact force and will not perform strong invalid impact movement from the preset threshold rotating speed to the no-load rated rotating speed.

[0013] The above-mentioned motor control module and method of the application do not rely on the load feedback from the workpiece, eliminate the step of determining the load of the workpiece based on many complex factors (including but not limited to the material of the workpiece, the structure of the electric tool, the structure of the impact device and the impact force generated, etc.), and are not only simple but also accurate.

[0014] The electric control module of the application is advantageous when the electric tool is used in highland or low temperature conditions. When started in these conditions, the viscosity of the lubricating grease in the electric tool is large, which is not conducive to the starting of the electric tool, so that the output rotating speed of the motor is kept at a preset threshold rotating speed which is lower than the no-load rated rotating speed for a period of time, and the rotating speed is low and the torque is large in this period of time, which is conducive to the starting of the electric tool. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a block diagram of the motor control module according to the principle of the application;

[0016] Figure 2 is Figure 1 is a case of the change curve of the output rotating speed of the motor in the motor control module of

[0017] Figure 3 is Figure 1a variation curve of the output rotational speed of the motor when the motor switch in the motor control module is actuated from the off position to the on position;

[0018] Figure 4 is Figure 1 an operation flow chart of the motor control module;

[0019] Figure 5 is a partial sectional view of one exemplary embodiment of the power tool equipped with Figure 1 the motor control module. DETAILED DESCRIPTION

[0020] The present application is first directed to a motor control module for a power tool, the motor control module of the present application is applicable to all common power tools, and is particularly advantageous when applicable to power tools that output reciprocating linear motion (or impact or hammering motion), such as electric hammers, hammer drills.

[0021] As shown in the block diagram of Figure 1 the motor control module 100 of the present application includes a motor 110, a motor switch 120 for actuating the motor 110, a motor controller 130 for controlling the motor, and a mode selector 140 configured for selecting one of a plurality of control modes provided by the motor control module 100. For example, the motor control module 100 of the present application can be provided with two control modes: a first control mode for controlling the output rotational speed of the motor 110 independently of the real-time rotational speed of the motor 110, and a second control mode for controlling the output rotational speed of the motor 110 in relation to the real-time rotational speed of the motor 110.

[0022] With the motor control module configured as shown in Figure 1 , when the power tool starts operation, first the motor control mode is selected by the mode selector 140, then the motor switch 120 is actuated to start the motor 110, the motor controller 130 controls the motor 110 based on the selected motor control mode until the output rotational speed of the motor 110 reaches a steady state, and finally the operation switch of the power tool is actuated, and the power tool starts the machining operation on the workpiece.

[0023] In the case where the motor switch 120 is an ON / OFF type switch that only includes an on position and an off position, the motor switch 120 is actuated to the on position, and the final steady rotational speed corresponding to the steady state described above is the no-load rated rotational speed NR corresponding to the on position.

[0024] In the case where the motor switch 120 includes an off position and a plurality of (at least two) on positions, the motor switch 120 can be a multi-stage switch that provides the plurality of on positions in a discrete form, in which each on position corresponds to a different switch actuation (e.g., push, rotation, or dial) position. The stable state described above is a stable state corresponding to the on position in which the motor switch 120 is placed (hereinafter, referred to as a "target on position"), and the final stable rotational speed in the stable state corresponds to the position setting rotational speed of the target on position. In the plurality of on positions provided by the motor switch 120, each on position has a respective position setting rotational speed, and different on positions have different position setting rotational speeds. The maximum value among the position setting rotational speeds corresponding to the respective on positions is equal to or set to (referred to as) the no-load rated rotational speed NR of the motor, and the position setting rotational speeds of the remaining on positions are each less than or lower than the no-load rated rotational speed NR.

[0025] For example, the motor switch 120 is a two-stage switch that includes an off position, a first on position having a first position setting rotational speed N1, and a second on position having a second position setting rotational speed N2. When the motor switch 120 is actuated to the second on position, which is the target on position, the motor reaches and stabilizes at the second position setting rotational speed N2.

[0026] In the case where the motor switch 120 includes an off position and a plurality of (at least two) on positions, the motor switch 120 can be a multi-stage switch that provides the plurality of on positions in a discrete form, in which each on position corresponds to a different switch actuation (e.g., push, rotation, or dial) position. The stable state described above is a stable state corresponding to the on position in which the motor switch 120 is placed (hereinafter, referred to as a "target on position"), and the final stable rotational speed in the stable state corresponds to the position setting rotational speed of the target on position. In the plurality of on positions provided by the motor switch 120, each on position has a respective position setting rotational speed, and different on positions have different position setting rotational speeds. The maximum value among the position setting rotational speeds corresponding to the respective on positions is equal to or set to (referred to as) the no-load rated rotational speed NR of the motor, and the position setting rotational speeds of the remaining on positions are each less than or lower than the no-load rated rotational speed NR.

[0027] In the present application, the term "actuation" is limited to actuation of the motor switch 120 from the off position to the on position or switching between different on positions with the power source turned on, and does not include switching between positions with the power source turned off.

[0028] When the motor switch 120 is actuated to the target on position, the rotational speed at which the motor 110 finally reaches is referred to as the final stable rotational speed. The final stable rotational speed can be the no-load rated rotational speed NR described above (when the motor switch 120 is an ON / OFF type switch, or when the motor switch 120 is a multi-stage switch or a stepless switch and is placed in an on position having a position setting rotational speed equal to the no-load rated rotational speed NR), or can be a position setting rotational speed less than the no-load rated rotational speed NR (when the motor switch 120 is a multi-stage switch or a stepless switch and is placed in an on position having a position setting rotational speed less than the no-load rated rotational speed NR).

[0029] In combinationFigure 4 The motor control method performed by the motor control module 100 of the present application comprises a selection operation P1 of selecting a motor control mode, in which the user selects a motor control mode from the above-mentioned first control mode and second control mode by means of the mode selector 140.

[0030] The motor control method further comprises an operation P2 of actuating the motor switch 120 after the motor control mode is selected. In this operation, the motor switch 120 is actuated from the first gear position (which can be the OFF gear position, or can be one gear position other than the target gear position, according to the type of the motor switch or actual needs) to the target gear position, which can be the only gear position of an ON / OFF type switch, or one of the multiple gear positions provided by the above-mentioned multi-gear or stepless switch.

[0031] Finally, the motor control method further comprises a control operation P3 performed by the motor controller 130 of the motor control module 100. In this operation, the motor controller 130 controls the output speed of the motor 110 based on the motor control mode selected by the user in operation P1.

[0032] Specifically, the control operation P3 comprises: in the first control mode, controlling the motor 110 to perform a preset automatic control logic: when the first gear position is the OFF gear position (regardless of the type of the motor switch), changing the output speed of the motor 110 from an initial speed 0 to a preset threshold speed Npre and maintaining the output speed of the motor 110 at the preset threshold speed Npre for a preset time period Tpre, and then changing the output speed of the motor 110 from the preset threshold speed Npre to a gear set speed corresponding to the target gear position.

[0033] This is illustrated in Figure 2 , in which the motor controller 130 controls the motor 110 such that the output speed of the motor 110 changes from 0 to a preset threshold speed Npre in a first time period from a starting time O to a time T0, maintains the output speed of the motor 110 at the preset threshold speed Npre for a preset time period Tpre starting from the time T0, and changes from the above-mentioned preset threshold speed Npre to a final stable speed N, i.e. a gear set speed corresponding to the target gear position, in a second time period from a time T1 at the end of the preset time period Tpre to a time T2, as shown in Figure 2 and 3 . Figure 2 and 3 , in which the abscissa represents time T and the ordinate represents the output speed RPM of the motor.

[0034] The case conforming to the present automatic control logic includes: 1) the motor switch 120 is an ON / OFF type switch, the final stable speed N is the no-load rated speed NR, and the curve distribution of the output speed of the motor is as shown inFigure 2 2) the motor switch 120 is a multi-stage switch or a stepless switch and is actuated from the off gear to a corresponding on gear with a gear set speed that is the maximum gear set speed, i.e. the no-load rated speed NR, at which the final steady speed is also the no-load rated speed NR, as shown in the curve of FIG. 3; Figure 2 3) the motor switch 120 is a multi-stage switch or a stepless switch and is switched from the off gear to a certain (target) on gear with a gear set speed that is less than the no-load rated speed NR but greater than a preset threshold speed Npre, at which the final steady speed N corresponding to the target on gear set speed is not equal to, but less than the no-load rated speed NR, so that the output speed of the motor 110 is raised from the preset threshold speed Npre to the final steady speed N equal to the corresponding gear set speed, but not the no-load rated speed NR, in a second time period from T1 to T2, as shown in the curve of FIG. 4; Figure 2 4) the motor switch 120 is a multi-stage switch or a stepless switch and is actuated from the off gear to a target on gear with a gear set speed that is less than the preset threshold speed Npre, at which the final steady speed N is not equal to, but less than the no-load rated speed NR and also less than the preset threshold speed Npre, so that the output speed of the motor 110 is reduced from the preset threshold speed Npre to the final steady speed N equal to the corresponding gear set speed, in a second time period from T1 to T2, as shown in the curve of FIG. 5. Figure 3

[0035] ​The motor control module and the motor control method according to the present application operate independently of the load from the workpiece to which the power tool is applied, eliminating the complex process of determining the workpiece load, simple and reliable. The preset threshold speed Npre in the module and method can be set to 1 / 6-2 / 3 of the no-load rated speed NR of the motor 110 (the speed set for the largest gear when the motor switch 120 includes multiple gears), and is particularly preferably 1 / 3-1 / 2. The preset time period Tpre for maintaining the preset threshold speed Npre can be set to 0.2s-3s, and is particularly preferably 0.2s-1s. The selection or setting of these preset parameters, particularly the preset threshold speed Npre, makes the energy generated by the motor when the power tool is turned on at this speed sufficient to shake or eject the drill bit that is installed in the power tool but not correctly locked or the drill bit that is incorrectly installed and too small in size from the power tool, while ensuring that the energy or speed of the drill bit ejected or ejected is small, or is only shaken and will not be ejected, and will not cause harm to nearby personnel or objects. On the other hand, it also ensures that the impact device will remain in the no-load position during or after the above-mentioned preset time period, before reaching the final stable speed (e.g. the higher no-load rated speed), so as to ensure that the impact device (hammer drill) will not have impact force during the process from the preset threshold speed to the no-load rated speed, and to ensure that the power tool will not have impact force after the preset time period after being turned on and before being applied to the workpiece, thereby avoiding harm to nearby personnel or objects. Therefore, even in the case where the drill bit is only shaken and not ejected, the drill bit will no longer be ejected because there is no longer an impact force, so the danger of high-speed ejection of the drill bit is also avoided.

[0036] Optionally, the first time period can be ≤0.3s, and the second time period can be ≤0.3s. Advantageously, in order to make the start of the motor 110 not too slow / the start time not too long, the total start time of the motor 110, i.e. the sum of the first time period and the second time period and the preset time period, can be set within 1s.

[0037] The automatic control logic further comprises: when the motor switch 120 comprises a plurality of open gears, and the first gear is not the off gear, the output rotating speed of the motor is directly changed from the gear setting rotating speed corresponding to the first gear to the gear setting rotating speed corresponding to the target open gear. Specifically, when the motor switch 120 is a multi-stage or stepless switch and the first open gear is actuated to the second or target open gear, at this time the output rotating speed of the motor has already (in the process of actuating from the off gear to the first open gear) experienced the operation of lasting for a preset time period Tpre at a preset threshold rotating speed Npre, that is, experienced the rotating speed interval of being low enough to pop out the drill bit or being low enough to only vibrate the drill bit without popping out but the impact device has returned to the no-load position, so there is no longer the risk of high-speed pop-out of the drill bit. Thereafter, the motor controller 130 controls the motor 110 to directly change the output rotating speed of the motor from the gear setting rotating speed corresponding to the first open gear to the gear setting rotating speed corresponding to the second open gear.

[0038] The control operation P3 further comprises: in the second control mode (if the second control mode is selected in operation P1), controlling the motor 110 to execute the preset real-time control logic. The real-time control logic comprises: when the motor switch 120 is actuated from a first gear with a gear setting rotating speed less than the preset threshold rotating speed Npre to a target open gear in the plurality of open gears with a gear setting rotating speed greater than or equal to the preset threshold rotating speed Npre, the output rotating speed of the motor 110 is changed from the gear setting rotating speed corresponding to the first gear to the gear setting rotating speed corresponding to the target open gear and finally stabilized at this rotating speed, and during this period, when the real-time measured rotating speed of the motor 110 reaches the preset threshold rotating speed Npre, the operation of lasting for a preset time period Tpre at the preset threshold rotating speed Npre is executed, wherein the preset threshold rotating speed Npre and the preset time period Tpre are set as described above in the first control mode. The first gear can be the off gear with a gear setting rotating speed of 0, or any open gear with a gear setting rotating speed less than the preset threshold rotating speed Npre.

[0039] The real-time control logic further comprises: when the motor switch 120 is actuated from a first gear with a gear setting rotating speed less than the preset threshold rotating speed Npre to a target open gear with a gear setting rotating speed less than the preset threshold rotating speed Npre (that is, the gear setting speeds of the two gears before and after the actuation action are both less than the preset threshold rotating speed Npre, and the first gear can be the off gear), or when the motor switch 120 is actuated from a first gear with a gear setting rotating speed greater than the preset threshold rotating speed Npre to a target open gear in the plurality of open gears (that is, the gear setting speed before the actuation action is greater than the preset threshold rotating speed Npre, at this time it must have already experienced the operation of lasting for a preset time period Tpre at the preset threshold rotating speed Npre), the output rotating speed of the motor is directly changed from the gear setting rotating speed corresponding to the first gear to the gear setting rotating speed corresponding to the target open gear.

[0040] According to this real-time control logic, when the electric tool is started, if the gear set speed of the target gear position, i.e. the final stable speed, is less than the preset threshold speed Npre, the output speed of the motor rises from 0 to the final stable speed, and the output speed of the motor does not reach the preset threshold speed Npre during this period, so the preset period Tpre at the preset threshold speed Npre is not executed. In this case, the energy generated by the electric tool is not enough to eject the drill bit that is installed in the electric tool but not correctly locked or the drill bit that is incorrectly installed and too small in size from the electric tool, or the energy is small enough to only make the drill bit vibrate but not to cause damage to people or objects.

[0041] If the gear set speed of the target gear position, i.e. the final stable speed, is greater than or equal to the preset threshold speed Npre, or if the motor switch 120 is a stepless switch and the actuating stroke continues to increase, the motor controller 130 executes the preset period Tpre at the preset threshold speed Npre when the real-time speed of the motor 110 reaches the preset threshold speed Npre, and then reaches the gear set speed corresponding to the target gear position. That is, the output speed of the motor rises from 0 or the low-speed gear position to the final stable speed, and the preset period Tpre at the preset threshold speed Npre is executed when the output speed of the motor reaches the preset threshold speed Npre for the first time.

[0042] This second control mode is generally divided into two stages: one is before the speed reaches the preset threshold speed Npre from 0 after the start, the impact device may not return to the no-load position from the "wrong" load position due to the small impact energy, but it is enough to vibrate or eject the drill bit that is installed in the electric tool but not correctly locked or the drill bit that is incorrectly installed and too small in size from the electric tool, while ensuring that the energy or speed of the ejected drill bit is small or only vibrates without being ejected, and still does not cause damage to people or objects nearby. The other is based on the real-time detection of the motor speed, and the preset period Tpre is executed when the real-time speed of the motor reaches the preset threshold speed Npre for the first time. As described above, after the preset period Tpre, on the one hand, the drill bit that is installed in the electric tool but not correctly locked or the drill bit that is incorrectly installed and too small in size is vibrated or ejected from the electric tool, but the speed and energy are small enough or only vibrates without being ejected; on the other hand, it is ensured that the impact device returns to and remains in the no-load position, so that the impact device (hammer drill) does not have impact force during the process of the motor from the preset threshold speed to the no-load rated speed, and the danger of high-speed ejection of the drill bit is avoided even in the case that the drill bit only vibrates without being ejected.

[0043] The above is for the case that the target gear position is the high-speed gear position. Figure 1The motor control module 100 including the mode selector 140 is described in detail. The present application also relates to a motor control module not including the mode selector, and accordingly the motor control module only provides one of the first control mode and the second control mode. In this case, the control process of the motor no longer includes the operation of selecting the motor control mode, but directly executes the automatic or real-time motor control logic provided by the motor control module. Here, no further description is given.

[0044] The motor control module 100 of the present application is described in detail above, and the method of controlling the motor independently of the workpiece load is described in detail to avoid the safety accident caused by the inappropriate drill or tool flying out at high speed. Below, an exemplary embodiment of the power tool equipped with the motor control module 100 is described. Figure 5

[0045] As described above, the motor control module is advantageous for the power tool outputting the reciprocating linear motion. The illustrated exemplary power tool is a hammer drill outputting the reciprocating linear motion of the tool (drill) along the mounting direction of the tool (herein referred to as the longitudinal direction L), also referred to as hammering or impact motion, and / or the rotational motion around the longitudinal direction L. In other words, the hammer drill of the present application can perform hammer operation, drill operation, and hammer drill operation on the workpiece. Those skilled in the art should understand that the motor control module of the present application is not only applicable to the illustrated hammer drill power tool, but also applicable to any other situation in which the output rotational speed of the motor rapidly increases when the power tool is started again if the internal parts of the power tool do not correctly return to the default position at the time of shutdown, and also applicable to any situation in which the output rotational speed of the motor needs to stay within a certain specific rotational speed range for a period of time during the startup of the power tool to check the status of the internal parts of the power tool. As an example, the motor control module 100 of the present application is also applicable to the electric hammer structure which only outputs hammer operation.

[0046] The illustrated power tool generally includes a tool holder 20 at the front end of the power tool, a tool body 40 connected to the rear of the tool holder 20, and a motor control unit 100.

[0047] The holder 20 can be any holder structure commonly known in the power tool field, or any improved holder structure, as long as it can be connected to the impact device of the present application. The illustrated holder 20 is only an exemplary structure that can be used in the power tool equipped with the motor control module 100 of the present application.

[0048] The holder 20 includes a holder body 22 defining a tool receiving through hole 21 extending along the longitudinal direction L. The front end of the tool receiving through hole 21 is adapted to receive the tool in the front-to-rear direction (as viewed in the longitudinal direction L) from the front end of the holder 20. Figure 5 ​The rear end of the chuck body 22 extends to the inner bore 43 of the tubular body 42 of the tool body 40, which will be described later, so that the tool received in the tool receiving through hole 21 can receive the driving or impact of the impact device installed in the inner bore 43 to perform the task of machining the workpiece. The directional terms "longitudinal direction L", "front" and "rear" in the present application are understood with reference to the drawings.

[0049] The chuck body 22 includes a tool locking member hole 23 formed therein, and a tool locking member 24 is received in the tool locking member hole 23 and is configured to extend into an elongated slot formed on the shank of a suitable tool when the shank is inserted into the tool receiving through hole 21 to engage the shank of the tool and prevent the tool from being pulled out and falling off in the forward direction opposite to the insertion direction during operation. In the drawings, the tool locking member 24 can be a ball, but is not limited to a ball. The elongated slot formed on the shank of the tool is elongated in the longitudinal direction L to allow the tool locking member 24 to slide in the elongated slot when the tool reciprocates in the output longitudinal direction L. On the other hand, the inner surface of the chuck body 22 for forming the tool receiving through hole 21 is provided with a key groove 27, and the chuck body 22 is connected to the shank of the tool by the key, so that the chuck body 22 can drive the tool to rotate when it rotates to output the drilling operation.

[0050] The tool body 40 includes a tubular body 42, also referred to as a "hammer tube", which includes an inner bore 43 extending in the longitudinal direction L, and an impact device 50 is arranged in the inner bore 43 of the tubular body 42. In the illustrated embodiment, the impact device 50 includes an impact member 52 that generates an impact force driven by a motor 110 of a motor control module 100, and an intermediate pin 54 that transmits the impact force of the impact member 52 to the tool.

[0051] For the hammer drill structure illustrated, on the one hand, the tubular body 42 of the tool body 40 and the chuck body 22 of the chuck device 20 are mechanically connected. The motor 110 of the motor control module 100 drives the tubular body 42 to rotate about the longitudinal direction L via a transmission device (such as a gear transmission device), and the tubular body 42 drives the chuck body 22 of the chuck device 20, which in turn drives the tool to rotate by key coupling, so that the tool performs the drilling operation. On the other hand, the motor 110 of the motor control module 100 can also drive the impact device 50 in the tubular body 42 to reciprocate linearly along the longitudinal direction L, for example, via a swing bearing, and the tool receiving through hole 21 of the chuck body 22 of the chuck device 20 is in communication with the inner bore 43 of the tubular body 42 of the tool body 40, so that the impact device 50 reciprocating linearly along the longitudinal direction L drives the tool to output synchronous reciprocating linear motion, thereby performing the hammering operation.

[0052] For the latter reciprocating linear motion, the impact device 50 has a forwardmost position, i.e. an unloaded or unloading position a, and a rearwardmost position, i.e. a loaded or loading position b Figure 5 The "a" and "b" in the above equation intuitively show the position of the intermediate pin 54 when the impact device 50 is at the unloaded position and the loaded position, respectively), and the impact device 50 is capable of reciprocating between the unloaded position a and the loaded position b. At the rearwardmost position, i.e. the loaded position b, the impact device 50 is indirectly coupled with and driven by the motor 110 to generate the impact force and impact the drill bit; at the forwardmost position, i.e. the unloaded position a, the impact device 50 is decoupled from the motor 110 and is not driven by the motor 110.

[0053] The tool body 40 of the power tool further comprises a retaining device 60 disposed within the inner bore 43 of the tubular body 42, which is configured to exert a retaining force F on the impact device 50 such that the impact device 50 is retained at the unloaded position a when the tool bit of the power tool is not in contact with the workpiece (the suction force pulling or attracting the impact piece 52 rearward within the inner bore 43 due to the operation of the motor 110 is much smaller than the retaining force F) or the reaction force of the workpiece on the tool bit (and the sum of the suction force) is smaller than the retaining force F.

[0054] The intermediate pin 54 of the impact device 50 can comprise a pin body 72 and an annular protrusion 74 protruding radially outward from the outer circumferential surface of the pin body 72, the annular protrusion 74 having a forward outer surface 53 and a rearward outer surface 57. The tubular body 42 itself or the front stopper 47 and the rear stopper 49 mounted therein define a space 48 in the longitudinal direction L to accommodate the annular protrusion 74 of the intermediate pin 54 when the impact device 50 reciprocates between the unloaded position a and the loaded position b. The impact piece 52 comprises a front end portion 68 with an increased outer diameter.

[0055] The retaining device 60 is an elastic ring 62 mounted in the inner bore 43 of the tubular body 42. The position shown is the loaded position b of the impact device 50, in which the elastic ring 62 is clamped on the rear end outer circumferential surface of the pin body 72 of the intermediate pin 54. When the impact device 50 comprising the impact piece 52 and the intermediate pin 54 moves from the loaded position b to the unloaded position a, the impact piece 52 pushes the intermediate pin 54 to move forward together, the rear end of the intermediate pin 54 moves out of the engagement with the elastic ring 62, the front end portion 68 of the impact piece 52 passes the elastic ring 62 by deforming the elastic ring 62 further outward, and reaches the unloaded position a when the forward outer surface 53 of the annular protrusion 74 of the intermediate pin 54 abuts against the front stopper 47. At this time, the rearward outer surface of the front end portion 68 of the impact piece 52 and the elastic ring 62 are in engagement. To move the impact piece 52 rearward, the retaining force F of the elastic ring 62 on the front end portion 68 needs to be overcome.

[0056] As mentioned above, the impact device 50 moves from the load position b to the unloaded position a. During normal operation of the power tool, this movement causes the tool bit to perform a hammering operation on the workpiece. The tool bit then, under the strong reaction force of the workpiece, overcomes the above-mentioned holding force F to retract the impact device 50 back to the load position b, and so on.

[0057] Under the control of the motor control module 100 of the present application, the output rotational speed of the motor 110 is raised from 0 to a preset threshold rotational speed Npre and maintained for a preset time period. During this period, the impact piece 52 of the impact device 50 in the load position b is subjected to an impact force generated by the motor drive, which is sufficient to push the intermediate pin 54 together over the elastic ring 62 to reach the unloaded position a from the load position b, but not so large as to cause a strong impact, thus reducing / avoiding the risk, as mentioned above. At this time, the power tool is not applied to the workpiece, the tool bit is not subjected to the reaction force of the workpiece, and the suction force generated by the motor 100 at this output rotational speed in the inner hole 43 of the tubular body 42 to suck the impact piece 52 back is obviously far insufficient to overcome the holding force F, so the impact device 50 including the impact piece 52 and the intermediate pin 54 is reliably maintained in the unloaded position a.

[0058] Therefore, this setting of the motor control module well compensates for the "mistake" of the impact device 50 not returning to the unloaded position a correctly after the previous operation of the power tool ends, and even when the motor 110 reaches the final stable rotational speed at the highest unloaded rated rotational speed NR, it will not cause a strong impact and a strong invalid impact (hammering), because at this time the impact device 50 has returned to the unloaded position a. On the other hand, as mentioned above, in the case of an incorrectly locked or incorrectly installed too small tool bit installed in the power tool, the return of the impact device 50 to the unloaded position a is sufficient to eject the tool bit, so that the operator can timely recognize and correct the installation of the tool bit. This effectively avoids the safety accidents that may be caused by the strong ejection of the tool bit when the output rotational speed of the motor rapidly reaches a high final stable rotational speed.

[0059] In addition, as can be seen from the above description, the above technical solution of returning the impact device 50 to the idle position a and ejecting the incorrectly installed tool in time is completely realized by the motor control module 100, and does not depend on the load from the workpiece after the electric tool is applied to the workpiece, which is very advantageous in solving the problem in the starting process of the electric tool in a form without any safety risk, and solving the problem that no damage to the workpiece is caused before the electric tool is applied to the workpiece. Otherwise, if the technical solution for solving the above technical problem depends on the load from the workpiece, the electric tool has been applied to the workpiece, and not only the load from the workpiece needs to be accurately detected (as known, the detection of the load from the workpiece is related to many factors, including but not limited to the material of the workpiece, the impact force of the electric tool, etc., so it is relatively difficult to realize), but also the risk that the tool ejected may "hit" the workpiece being machined, causing damage to the workpiece.

[0060] The above description with reference to the illustrated hammer drill embodiment describes the principles of the present application. In the illustrated embodiment, the impact device 50 includes an impact piece 52 and an intermediate pin 54, and the entire impact device 50 is held in the idle position a by the elastic member 62 of the holding device 60 engaging the front end 68 of the impact piece 52. However, those skilled in the art should understand that the holding device 60 can have any known structure in the art, or any improved structure, as long as it can be used with the impact device 50 of the present application.

[0061] In one embodiment, the holding device holding the impact device 50 in the idle position a not only includes the elastic ring 62 engaging the impact piece 52, but the holding device 60 can also include a blocking member, such as an elastic member such as a spring, for providing resistance to the rearward movement of the intermediate pin 54 of the impact device 50. The blocking member can engage the intermediate pin 54 in any manner, for example, a spring is arranged between the protruding portion 74 and the rear limiting member 49, and is sleeved on the pin body 72 of the intermediate pin 54, to provide resistance to the rearward movement of the intermediate pin 54.

[0062] The above detailed description is only used to illustrate the present application, and is not a limitation on the present application. Those skilled in the art can make various changes and modifications to the technical solution of the present application without departing from the scope of the present application, therefore all equivalent technical solutions also belong to the scope of the present application, and the patent protection scope of the present application should be defined by the claims.

Claims

1. A motor control module (100) for a power tool, the power tool being configured for outputting at least a reciprocating linear motion, the motor control module (100) comprising: a motor (110); a motor switch (120) for actuating the motor (110), the motor switch (120) having an off-gear with a gear setting speed of zero and at least one on-gear, each of the at least one on-gear having a respective gear setting speed; and a motor controller (130) configured to execute an automatic control logic comprising: automatically controlling the motor (110) to vary its output speed from 0 to a preset threshold speed Npre and to maintain at the preset threshold speed Npre for a preset time period Tpre, and then to vary from the preset threshold speed Npre to a gear setting speed corresponding to a target on-gear of the at least one on-gear, when the motor switch (120) is actuated from the off-gear to the target on-gear, wherein the preset threshold speed Npre is 1 / 6-2 / 3 of a no-load rated speed NR of the motor and the preset time period Tpre is 0.2s-3s.

2. The motor control module (100) according to claim 1, wherein: the motor switch (120) is an ON / OFF switch comprising only the target on-gear and the off-gear, the gear setting speed being a no-load rated speed NR of the motor (110); or the motor switch (120) is a multi-stage switch and the at least one on-gear comprises a plurality of on-gears provided in a discrete form, or the motor switch (120) is a stepless switch and the at least one on-gear comprises a plurality of on-gears provided in a continuous form, a maximum of the gear setting speeds of the plurality of on-gears being equal to the no-load rated speed NR of the motor (110).

3. A motor control module (100) for a power tool, the power tool being configured for outputting a reciprocating linear motion, the motor control module (100) comprising: a motor (110); a motor switch (120) for actuating the motor (110), the motor switch (120) having an off-gear with a gear setting speed of zero and a plurality of on-gears, each of the plurality of on-gears having a respective gear setting speed; and a motor controller (130) configured to control the motor (110) based on a real-time measured motor speed to execute a real-time control logic comprising: when the motor switch (120) is actuated from the first gear position having a gear set speed less than a preset threshold speed Npre to a target gear position having a gear set speed greater than or equal to the preset threshold speed Npre among the plurality of gear positions, causing the output speed of the motor (110) to change from the gear set speed corresponding to the first gear position to the gear set speed corresponding to the target gear position, and during the change, when the real-time measured motor (110) speed reaches the preset threshold speed Npre, performing a preset time period Tpre at the preset threshold speed Npre, wherein the preset threshold speed Npre is 1 / 6-2 / 3 of the no-load rated speed NR of the motor and the preset time period Tpre is 0.2s-3s.

4. The motor control module (100) according to claim 3, wherein, the motor switch (120) is a multi-stage switch and the plurality of gear positions are a plurality of gear positions provided in a discrete form, or the motor switch (120) is a stepless switch and the plurality of gear positions are a plurality of gear positions provided in a continuous form, the maximum value among the gear set speeds of the plurality of gear positions being equal to the no-load rated speed NR of the motor (110).

5. A motor control module (100) for a power tool, the power tool being configured for outputting a reciprocating linear motion, the motor control module (100) comprising: a motor (110); a motor switch (120) for starting the motor (110), the motor switch (120) having a gear position with a gear set speed of zero and at least one gear position, each of the at least one gear position having a respective gear set speed; a mode selector (140) configured for alternative selection between a first control mode of controlling the output speed of the motor (110) independently of the real-time speed of the motor (110) and a second control mode of controlling the output speed of the motor (110) in relation to the real-time speed of the motor (110); and a motor controller (130) configured to execute an automatic control logic in the first control mode and a real-time control logic in the second control mode, wherein the automatic control logic comprises, when the motor switch (120) is actuated from the gear position to a target gear position among the at least one gear position, automatically controlling the motor (110) to: cause its output speed to change to a preset threshold speed Npre and to last for a preset time period Tpre at the preset threshold speed Npre, and then from the preset threshold speed Npre to the gear set speed corresponding to the target gear position, wherein the preset threshold speed Npre is 1 / 6-2 / 3 of the no-load rated speed NR of the motor and the preset time period Tpre is 0.2s-3s. ​ The real-time control logic comprises: the at least one open-gear position comprises a plurality of open-gear positions, when the motor switch (120) is actuated from a first open-gear position with a gear-set speed less than a preset threshold speed Npre to a target open-gear position in the plurality of open-gear positions with a gear-set speed greater than the preset threshold speed Npre, the output speed of the motor (110) is changed from the gear-set speed corresponding to the first open-gear position to the gear-set speed corresponding to the target open-gear position, and during the change, when the real-time speed of the motor (110) reaches the preset threshold speed Npre, a preset time period Tpre is performed at the preset threshold speed Npre, wherein the preset threshold speed Npre is 1 / 6-2 / 3 of the no-load rated speed NR of the motor and the preset time period Tpre is 0.2s-3s.

6. The electric machine control module (100) according to claim 1 or 2 or 5, wherein, The automatic control logic comprises: when the motor switch (120) comprises a plurality of open-gear positions, and when the motor switch (120) is actuated from a first open-gear position in the plurality of open-gear positions to a second open-gear position in the plurality of open-gear positions, the output speed of the motor is directly changed from the gear-set speed corresponding to the first open-gear position to the gear-set speed corresponding to the second open-gear position.

7. The electric machine control module (100) according to claim 3 or 4 or 5, wherein, The real-time control logic further comprises: when the motor switch (120) is actuated from a first open-gear position with a gear-set speed less than a preset threshold speed Npre to a target open-gear position with a gear-set speed less than the preset threshold speed Npre, or when the motor switch (120) is actuated from a first open-gear position with a gear-set speed greater than the preset threshold speed Npre to a target open-gear position in the plurality of open-gear positions, the output speed of the motor is directly changed from the gear-set speed corresponding to the first open-gear position to the gear-set speed corresponding to the target open-gear position.

8. The electric machine control module (100) according to any one of claims 1-5, wherein, The preset threshold speed Npre is 1 / 4-1 / 2 of the no-load rated speed NR, and the preset time period Tpre is 0.2s-1s.

9. The electric machine control module (100) of claim 8, wherein, The motor controller is further configured to control the motor (110) to have its output speed reach from 0 to the gear-set speed corresponding to the target open-gear position within 1s.

10. A power tool, comprising: a motor control module (100) according to any one of claims 1-9; a tubular body (42) defining an internal bore (43) in which the impact device (50) is housed; and a clamping device (20) comprising a clamping body (22) having a tool-receiving through-hole (21) adapted to receive a shank of a tool of the power tool, wherein during operation of the power tool, the motor (110) of the motor control module (100) drives the impact device (50), and the impact device (50) in turn drives the tool to perform a reciprocating linear motion, the impact device (50) having an unloaded position (a) in which it is decoupled from the motor (110) and a loaded position (b) in which it is coupled to the motor (110) to generate an impact force.

11. The electric power tool according to claim 10, further comprising a holding device (60) configured to hold the impact device (50) in the unloaded position (a).

12. The power tool of claim 11, wherein, The impact device (50) includes an impact piece (52) driven by the motor (110) to generate an impact force and an intermediate pin (54) that transmits the impact force on the impact piece (52) to the tool bit, wherein the holding device (60) includes a resilient ring (62) that engages the impact piece (52).

13. The electric power tool according to claim 12, further comprising a front stopper (47) and a rear stopper (49) provided in the tubular body (42), the intermediate pin (54) includes a pin body (72) and a protrusion (74) radially outwardly protruding from an outer circumferential surface of the pin body (72), the front and rear stoppers engage the protrusion (74) of the intermediate pin (54) when the impact device (50) is in the unloaded position (a) and the loaded position (b), respectively.

14. The power tool of claim 13, wherein, The holding device (60) further includes a blocking member that engages the intermediate pin (54) and provides resistance to the rearward movement of the intermediate pin (54).

15. The power tool of claim 14, wherein, The blocking member is a resilient member that is sleeved on the pin body (72) and is located between the protrusion (74) and the rear stopper (49) in the longitudinal direction (L).

16. The power tool of any of claims 10-15, wherein, The motor (110) of the motor control module (100) also drives the tubular body (42) to rotate, which in turn drives the clamping body (22) to rotate, which drives the tool bit to output a rotational motion.

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