阅读说明：本技术 电动工具 (Electric tool ) 是由 杨德中 鲜超 梅庆枭 于 2019-12-11 设计创作，主要内容包括：本发明公开了一种电动工具,使用电池包供电,电池包可拆卸地安装至电动工具,电动工具包括：电机；驱动电路,用于驱动电机输出动力；控制模块,用于控制驱动电路；储能元件,与驱动电路连接；限流元件,与储能元件串联连接,用于使储能元件以第一电流充电；开关元件,与储能元件串联电性连接,且与限流元件并联连接,用于使储能元件以第二电流充电或放电。本发明的电动工具,能够避免电池包在插入电动工具时滤波电容充电瞬间产生大电流而导致电动工具和电池包的连接端子处产生电火花等不利情况发生。(The invention discloses an electric tool, which is powered by a battery pack, wherein the battery pack is detachably arranged on the electric tool, and the electric tool comprises: a motor; the driving circuit is used for driving the motor to output power; the control module is used for controlling the driving circuit; the energy storage element is connected with the driving circuit; a current limiting element connected in series with the energy storage element for charging the energy storage element with a first current; and the switching element is electrically connected with the energy storage element in series and is connected with the current limiting element in parallel and used for enabling the energy storage element to be charged or discharged by second current. The electric tool can avoid the unfavorable conditions that the filter capacitor charges and generates large current instantly when the battery pack is inserted into the electric tool, so that electric sparks are generated at the connecting terminal of the electric tool and the battery pack, and the like.)

1. A power tool powered using a battery pack removably mounted to the power tool, the power tool comprising:

a motor;

the driving circuit is used for driving the motor to output power;

the control module is used for controlling the driving circuit;

the energy storage element is connected with the driving circuit;

a current limiting element connected in series with the energy storage element for charging the energy storage element with a first current;

and the switching element is electrically connected with the energy storage element in series and is connected with the current limiting element in parallel and used for enabling the energy storage element to be charged or discharged by second current.

2. The power tool of claim 1,

the control module is configured to:

and after the energy storage element is charged by the current limiting element through the first current to reach a preset voltage threshold, controlling the switching element to be switched on so as to enable the current limiting element to be in a short circuit.

3. The power tool of claim 2,

the preset voltage threshold is equal or substantially equal to a voltage value of the battery pack.

4. The power tool of claim 1,

the control module is configured to:

and after the energy storage element is charged by the current limiting element through the first current to reach a preset electric quantity threshold value, controlling the switching element to be switched on so as to enable the current limiting element to be in a short circuit.

5. The power tool of claim 1,

the control module is configured to:

and after the energy storage element is charged with the first current through the current limiting element for a preset time, controlling the switching element to be switched on so as to enable the current limiting element to be in a short circuit.

6. The power tool of claim 1,

the switching element is a relay switch or a semiconductor switch.

7. The power tool of claim 1,

further comprising:

the positive connecting terminal is used for being connected with a positive power terminal of the battery pack;

a negative connection terminal for connecting to a negative power terminal of the battery pack;

the drive circuit includes:

the first driving end is connected with the positive connecting terminal;

the second driving end is connected with the negative connecting terminal;

the energy storage element is connected to the first driving end or the second driving end.

8. The power tool of claim 1, wherein:

further comprising:

a trigger mechanism operable to be triggered for activating the motor;

the signal switch is connected with the trigger mechanism in a correlation manner and is used for outputting a starting signal to the control module;

the control module is configured to:

and after receiving the starting signal output by the signal switch, outputting a first control signal to control the switching element to be switched on so as to enable the current limiting element to be in short circuit.

9. The power tool of claim 8, wherein:

the control module is configured to:

and after the switching element is switched on, outputting a second control signal to the driving circuit to enable the motor to rotate.

10. The power tool of claim 1,

further comprising:

and the first voltage detection circuit is used for detecting the voltage at two ends of the energy storage element.

Technical Field

The present invention relates to an electric power tool.

Background

Generally, a motor control system of an electric tool includes a capacitor having a large capacity, and when a battery pack is mounted to the electric tool and a voltage at a terminal of the capacitor is low, the battery pack charges the capacitor, and a large current is generated at a charging instant, which causes an electric spark between a connection terminal of the electric tool and a connection terminal of the battery pack.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide an electric tool which is powered by a battery pack and can avoid electric sparks at a connecting terminal.

In order to achieve the above object, the present invention adopts the following technical solutions:

a power tool powered using a battery pack removably mounted to the power tool, the power tool comprising: a motor; the driving circuit is used for driving the motor to output power; the control module is used for controlling the driving circuit; the energy storage element is connected with the driving circuit; a current limiting element connected in series with the energy storage element for charging the energy storage element with a first current; and the switching element is electrically connected with the energy storage element in series and is connected with the current limiting element in parallel and used for enabling the energy storage element to be charged or discharged by second current.

Optionally, the control module is configured to: and after the energy storage element is charged by the current limiting element through the first current to reach a preset voltage threshold, controlling the switching element to be switched on so as to enable the current limiting element to be in a short circuit.

Optionally, the preset voltage threshold is equal to or substantially equal to a voltage value of the battery pack.

Optionally, the control module is configured to: and after the energy storage element is charged by the current limiting element through the first current to reach a preset electric quantity threshold value, controlling the switching element to be switched on so as to enable the current limiting element to be in a short circuit.

Optionally, the value range of the ratio of the preset electric quantity threshold to the full electric quantity of the energy storage element is 0.7-1.

Optionally, the control module is configured to: and after the energy storage element is charged with the first current through the current limiting element for a preset time, controlling the switching element to be switched on so as to enable the current limiting element to be in a short circuit.

Optionally, the switching element is a relay switch.

Optionally, the switching element is a semiconductor switch.

Optionally, the switching element is a field effect transistor.

Optionally, the value range of the current value of the first current is 20 mA-1500 mA.

Optionally, the first current flows between the energy storage element and the battery pack; the second current flows between the energy storage element and the drive circuit.

Optionally, the battery pack includes: the battery cell group comprises a plurality of electrically connected battery cells; the positive power supply terminal is connected to the positive electrode of the electric core group; and the negative power supply terminal is connected to the negative electrode of the battery pack.

Optionally, the method further comprises: a positive connection terminal for connecting to the positive power terminal of the battery pack; a negative connection terminal for connecting to the negative power terminal of the battery pack; the drive circuit includes: the first driving end is connected with the positive connecting terminal; the second driving end is connected with the negative connecting terminal; the energy storage element is connected to the first driving end or the second driving end.

Optionally, the method further comprises: a trigger mechanism operable to be triggered for activating the motor; the signal switch is connected with the trigger mechanism in a correlation manner and is used for outputting a starting signal to the control module; the control module is configured to: and after receiving the starting signal output by the signal switch, outputting a first control signal to control the switching element to be switched on so as to enable the current limiting element to be in short circuit.

Optionally, the control module is configured to: and after the switching element is switched on, outputting a second control signal to the driving circuit to enable the motor to rotate.

Optionally, the method further comprises: and the first voltage detection circuit is used for detecting the voltage at two ends of the energy storage element.

Optionally, the method further comprises: and the second voltage detection circuit is used for detecting the voltage of the battery pack.

A power tool powered using a battery pack removably mounted to the power tool, the power tool comprising: a motor; the driving circuit is used for driving the motor to output power; the control module is used for controlling the driving circuit; the energy storage element is connected with the driving circuit; a protection circuit electrically connected between the energy storage element and the driving circuit; the protection circuit comprises a first circuit and a second circuit which are arranged in parallel; the first circuit is connected with the energy storage element and used for enabling the energy storage element to be charged with a first current; the second circuit is connected with the energy storage element and is used for enabling the energy storage element to be charged or discharged with a second current.

Optionally, the first circuit comprises a current limiting element connected in series with the energy storage element; the second circuit comprises a switching element, and the switching element is electrically connected with the energy storage element in series and is connected with the current limiting element in parallel.

Optionally, the control module is configured to: and after the energy storage element is charged with the first current through the current limiting element to reach a preset condition, controlling the switching element to be switched on so as to enable the current limiting element to be in a short circuit.

The invention has the beneficial effects that at the initial stage of installing the battery pack to the electric tool, the adverse conditions of electric sparks generated at the connecting terminal of the electric tool and the connecting terminal of the battery pack or current switch contact damage and the like caused by the generation of large current at the moment of charging the filter capacitor in the electric tool can be avoided.

Drawings

Fig. 1 is an external view structural view of an electric power tool as an embodiment;

fig. 2 is a circuit system diagram of a power tool as an embodiment;

fig. 3 is a circuit system diagram of a power tool as another embodiment;

fig. 4 is a circuit system diagram of a power tool as another embodiment;

fig. 5 is a circuit system diagram of a power tool as another embodiment.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

The power tool of the present invention includes, but is not limited to, the following: electric tools needing speed regulation, such as a screwdriver, an electric drill, a wrench, an angle grinder and the like, electric tools possibly used for grinding workpieces, such as a sander and the like, and a reciprocating saw, a circular saw, a curve saw and the like possibly used for cutting the workpieces; electric hammers and the like may be used as electric tools for impact use. These tools may also be garden-type tools, such as lawn mowers, snow throwers, suction blowers, pruners, and chain saws; in addition, the tools may be used for other purposes, such as a blender. It is within the scope of the present invention for such power tools to be able to employ the teachings of the following disclosure.

The electric tool of the invention is powered by a battery pack, and the battery pack is detachably mounted on the electric tool. The electric tool includes: a tool attachment for implementing a function of the power tool; a motor operably connected to the tool attachment for driving the tool attachment in operation.

Referring to fig. 1, an electric power tool 10 according to an embodiment is an electric power tool 10, taking a mower as an example, and the electric power tool 10 includes: motor 33, chassis 12, handle 13, wheels 14 and blades (not shown). Of course, the power tool 10 may also be a riding lawn mower, or a power tool that performs other functions.

The blade, which serves as a tool attachment for the lawn mower for performing the mowing function of the lawn mower, is provided in the chassis 12.

The motor 33 is operatively connected to the tool attachment to drive the tool attachment in operation. In the case of a lawnmower, the tool accessory is a blade, the motor 33 is operatively connected to the blade, and the motor 33 is used to drive the blade in rotation to achieve a mowing function. The motor 33 may be directly connected to the blade or may be connected to the blade through a transmission or a reduction mechanism to drive the blade.

The chassis 12 is used to carry and mount the motor 33. The chassis 12 is formed with a cutting cavity (not shown). The blade rotates within the cutting chamber. The motor 33 may be a motor 33 powered by electric power or an internal combustion engine powered by fuel combustion. Specifically, the motor 33 is a brushless motor. In the present embodiment, the power tool 10 is supplied with power using the battery pack 20. The mower is provided with a battery compartment 17 for accommodating a battery pack 20, and the battery compartment 17 is provided at an upper portion of the chassis 12.

The handle 13 is held by a user to operate the power tool 10. For a lawnmower, the handle 13 is used to propel the lawnmower. The handle 13 is connected to the chassis 12. For a walk-behind mower, a linkage 131 is also included. The link 131 connects the handle 13 and the chassis 12. As an alternative embodiment, the handle 13 may be formed as one piece with the link 131. Optionally, the mower further comprises a trigger 15 and a switch box 16, the trigger 15 being used to control the motor 33. The trigger 15 is rotatably connected to a switch box 16, and the switch box 16 is fixed to the handle 13 or the link 131.

The wheels 14 rotate relative to the chassis 12 to enable movement of the mower over the ground. As an alternative embodiment, the mower includes a self-propelled motor that drives the wheels 14 in rotation.

As described above, the electric power tool 10 is not limited to the above-described mower, and may be another electric power tool, such as a garden-type electric power tool of a riding mower, a snow blower, a suction blower, a pruner, and a chain saw, a hand-held electric power tool of a reciprocating saw, a circular saw, a jig saw, a circular saw, an angle grinder, an electric drill, a screwdriver, an electric drill, a wrench, or a table-type tool.

Referring to fig. 2-5, the operation of the power tool 10 described above is further dependent upon the circuitry 30, with the circuitry 30 including circuit components, at least some of which are disposed on a circuit board (not shown) disposed in the housing 18 of the power tool. The circuitry 30 of the power tool 10 generally includes: a control module 31, a drive circuit 32, a motor 33, an energy storage element 34, and a battery pack 20.

The battery pack 20 includes a casing 21 (fig. 1) and a battery core pack 22 accommodated in the casing 21, the battery core pack 22 includes a plurality of electrically connected battery cells 221, the battery cells 221 can be repeatedly charged, and the plurality of battery cells 22 are electrically connected to form the battery core pack 22. The battery pack 20 further includes power terminals for connection with the connection terminals of the power tool 10, and the connection terminals of the battery pack 20 include a positive power terminal B + and a negative power terminal B-, which are electrically connected to the positive and negative poles of the electric core pack 22, respectively. The connection terminals of the power tool 10 include a positive connection terminal T + and a negative connection terminal T-for connection with a positive power supply terminal B + and a negative power supply terminal B-of the battery pack 20, respectively, to transmit electric power. When the battery pack 20 is mounted to the power tool 10, the positive power terminal B + and the negative power terminal B-of the battery pack 20 are electrically connected to the positive connection terminal T + and the negative connection terminal T-of the power tool 10, respectively, to transmit electric power.

As an embodiment, the power tool 10 includes a current switch SW (fig. 2) provided in the switch box 16, the current switch SW being connected in association with the trigger 15, the current switch SW being capable of being triggered by the trigger 15 to change an on-off state. The current switch SW is connected in series in the power transmission electric circuit of the battery pack 20 and the power tool 10, and is used for allowing or prohibiting the current from the battery pack 20. Specifically, one end of the current switch SW is connected to the positive electrode connection terminal T + of the power tool 10, and the other end is connected to the drive circuit 32, the energy storage element 34, and the control module 31. In another embodiment, the power tool 10 does not include the current switch SW, but uses the signal switch K (fig. 3) to trigger the control module 31 to make the control module 31 output a signal to the driving circuit 32, so as to control the driving circuit 32 to operate. The signal switch K is connected with the trigger 15 in an associated mode, and the signal switch K is triggered by the trigger 15 to change the on-off state. The signal switch K is electrically connected to the control module 31 and is configured to output a start signal to the control module 31. Specifically, the control module 31 can detect the state of the signal switch K, and when the signal switch K is in the triggered state, the control module 31 outputs a start signal to the control module 31, and the control module 31 outputs a control signal to the driving circuit 32 to enable the driving circuit 32 to operate. In the present embodiment, the trigger 15 is operable to be triggered for starting the electric tool 10 or the motor 33 as a trigger mechanism.

The control module 31 is electrically connected to the driving circuit 32 for outputting a driving signal to control the driving circuit 32 to operate, and in some embodiments, the control module 31 employs a dedicated control chip (e.g., MCU, micro control module, Microcontroller Unit). Optionally, the control chip includes a power driving module therein, the utilization driving module improves the driving capability of the control module 31 for outputting signals, and the power driving module may also be implemented by an external power driving module. The power tool 10 also includes a power module (not shown) for converting electrical energy from the battery pack 20 to electrical energy for use by the control chip or other electronic components in the control module 31.

The driving circuit 32 is connected with the motor 33 and is used for driving the motor 33 to output power. In one embodiment, the motor 33 is a brushless dc motor, and the motor 33 includes a rotor, a stator, and windings. The drive circuit 32 is connected to the windings of the motor 33, in particular via the three-phase poles U, V, W of the motor 33. The driving circuit 32 specifically includes at least one switching element for changing an on-off state according to a control signal of the control module 31, thereby changing an energization state of a winding of the motor 33.

In one embodiment, the driving circuit 32 is a three-phase bridge circuit, and the driving circuit 32 includes switching elements VT1, VT2, VT3, VT4, VT5, VT6, and switching elements VT1, VT2, VT3, VT4, VT5, and VT6 to form a three-phase bridge, where VT1, VT3, and VT5 are upper bridge driving switches, and VT2, VT4, and VT6 are lower bridge driving switches. The switching elements VT1-VT6 can be selected from field effect transistors, IGBT transistors, etc. Taking a field effect transistor as an example, the gate terminals of the switching elements are electrically connected to the power driving circuit 211 of the control module 31, and the drain or the source of each switching element is electrically connected to the winding of the motor 33. The switching elements VT1-VT6 change the on state according to the driving signal output by the control module 31, thereby changing the voltage state loaded on the winding of the motor 33 by the battery pack 20 and driving the motor 33 to operate.

In order to rotate the motor 33, the driving circuit 32 has a plurality of driving states, in which a stator winding of the motor generates a magnetic field, and the control module 31 is configured to output a corresponding driving signal to the driving circuit 32 according to a rotor rotation position of the motor 33 to enable the driving circuit 32 to switch the driving states, so as to change a state of a voltage applied to the winding of the motor 33, generate an alternating magnetic field to drive the rotor to rotate, and further drive the motor. The rotor rotation position of the motor 33 can be obtained by detecting a position sensor, or by sampling a bus current of the motor and/or a terminal voltage of the motor and performing corresponding calculation.

The drive circuit 32 has a first drive terminal 32a and a second drive terminal 32b, wherein the first drive terminal 32a is connected to the positive connection terminal T +, and the second drive terminal 32b is connected to the negative connection terminal T-.

The energy storage element 34 is connected to the driver circuit 32 for filtering the driver circuit 32. Specifically, the energy storage element 34 is connected to the first driving end 32a or the second driving end 32 b. The energy storage element 34 includes at least one electrolytic capacitor C, that is, the energy storage element 34 may include one electrolytic capacitor C or a plurality of electrolytic capacitors C connected in parallel.

In the initial stage of mounting the battery pack 20 to the power tool 10, the voltage across the electrolytic capacitor C is low, the battery pack 20 charges the electrolytic capacitor C, the voltage difference between the battery pack 20 and the electrolytic capacitor C is large, and a large current is generated at the moment of charging the electrolytic capacitor C, which may cause an electric spark to be generated between the connection terminal of the power tool 10 and the connection terminal of the battery pack 20, if the power tool 10 is provided with the power switch SW (fig. 1) connected to the positive power terminal T + of the power tool 20, the electrolytic capacitor C is connected behind the power switch SW, and when the power switch SW is closed, the contact of the power switch SW may be ablated or stuck by the large current.

The power tool 10 further includes a protection circuit 35, and the protection circuit 35 is electrically connected between the energy storage element 34 and the drive circuit 32. The protection circuit 35 includes a first circuit 351 and a second circuit 352 arranged in parallel, the first circuit 351 is connected with the energy storage element 34 for charging the energy storage element 34 with a first current; the second circuit 352 is connected to the energy storage element 34 for charging or discharging the energy storage element 34 with the second current.

In particular, the first circuit 351 comprises a current limiting element 3511, the current limiting element 3511 being connected in series with the energy storage element 34, the energy storage element 34 being chargeable with a first current through said current limiting element 351, the current limiting element 351 being connected in series on a charging circuit of the energy storage element 34. A first current flows between the energy storage element 34 and the battery pack 20.

In the embodiment of fig. 2, the power tool 10 includes a current switch SW, and when the battery pack 20 is mounted to the power tool 10 and the current switch SW is turned on, the battery pack 20 charges the energy storage element 34 with a first current through the current limiting element 3511.

In the embodiment of fig. 3, the power tool 10 does not include the current switch SW, but includes the signal switch K, and when the battery pack 20 is mounted to the power tool 10, the battery pack 20 charges the energy storage element 34 with the first current through the current limiting element 3511. In some embodiments, the current limiting element 3511 may be a resistor R.

The second circuit 352 includes a switching element 3521, the switching element 3521 being connected in series with the energy storage element 34 and in parallel with the current limiting element 3511 for charging or discharging the energy storage element 34 with the second current. A second current flows between the energy storage element 34 and the drive circuit 32. In one embodiment, the switching element 3521 is a semiconductor switch (see fig. 4), and in another embodiment, the switching element 3521 is a relay switch (see fig. 5).

The control module 31 is configured to: after the energy storage element 34 is charged with the first current through the current limiting element 3511 to reach the preset condition, the switch element 3521 is controlled to be turned on to short-circuit the current limiting element 3511.

In this way, the energy storage element 34 may be directly connected to the driving circuit 32 in parallel for filtering the driving circuit 32 after being charged with the first current to reach the preset condition, and after the driving circuit 32 is operated, the energy storage element 34 is charged or discharged with the second current, and the second current flows between the energy storage element 34 and the driving circuit 32, so that the energy storage element 34 can filter the driving circuit 32.

Optionally, the value range of the current value of the first current is 20 mA-1500 mA. That is, after the battery pack 20 is mounted to the electric power tool 10, the energy storage element 34 is charged with a small current, so as to prevent the electrolytic capacitor C from generating a large current at the charging moment to generate an electric spark between the connection terminal of the electric power tool 10 and the connection terminal of the battery pack 20, and when the electrolytic capacitor C is charged to a preset condition, the switching element 3521 is turned on to short-circuit the current limiting element 3511, so that the energy storage element 34 can be directly connected in parallel with the driving circuit 32 to normally filter the power of the driving circuit 32, and the current limiting element 3511 does not continuously consume the electric quantity of the battery pack 20.

Specifically, at the initial stage of mounting the battery pack 20 to the electric tool 10, the positive power terminal B + and the negative power terminal B-of the battery pack 20 are connected to the positive connection terminal T + and the negative connection terminal T-of the electric tool 10, the energy storage element 34 is charged through the current limiting element 3511, after the energy storage element 34 is charged to reach the preset condition, the control module 31 outputs a control signal to control the switching element 3521 to be turned on, so that the current limiting element 3511 is shorted, the energy storage element 34 is connected in parallel to the driving circuit 32, and after the driving circuit 32 operates, the energy storage element filters the driving circuit 32, and at this time, the energy storage element 34 is charged or discharged with the second current.

As an embodiment, the control module 31 is configured to: after the energy storage element 34 is charged with the first current through the current limiting element 3511 to reach the preset voltage threshold, the switching element 3521 is controlled to be turned on to short-circuit the current limiting element.

Optionally, the preset voltage threshold is equal or substantially equal to the voltage value of the battery pack 20. In this way, after the voltage difference between the energy storage element 34 and the battery pack 20 is small or zero, the energy storage element 34 is connected in parallel with the driving circuit 32, so that the driving circuit 32 can be normally filtered.

Referring to fig. 2 and 4, the power tool 10 optionally further includes a first voltage detection circuit 36 for detecting the voltage across the energy storage element 34. That is, the voltage detecting unit 36 detects whether the energy storage element 34 reaches the preset voltage threshold, and when the voltage detecting unit 36 detects that the voltage of the energy storage element 34 reaches the preset voltage threshold, the triggering control module 31 outputs a control signal to the switching element 3521 to turn on the switching element 3521, so that the current limiting element 3511 is short-circuited, and the energy storage element 34 can be directly connected in parallel to two ends of the driving circuit 32 for filtering the driving circuit 32.

Optionally, the power tool 10 further includes a second voltage detection unit (not shown) for detecting the voltage of the battery pack 20.

As an embodiment, the control module 31 is configured to: after the energy storage element 34 is charged by the current limiting element 3511 with the first current to reach the preset threshold, the switch element 3521 is controlled to be turned on to short-circuit the current limiting element 3511. Optionally, the value range of the ratio of the preset electric quantity threshold to the full electric quantity of the energy storage element 34 is 0.7-1.

Optionally, the control module 31 is configured to: after the energy storage element 34 is charged with the first current through the current limiting element 3511 for a preset time period, the switching element 3521 is controlled to be turned on to short-circuit the current limiting element 3511.

Referring to fig. 4, as an embodiment, the switch element 3521 is a semiconductor switch Q1, and the precedent element 3511 is a resistor R. The semiconductor switch Q1 is, for example, a field effect transistor or a bipolar transistor, taking the field effect transistor as an example, a gate of the field effect transistor is electrically connected to the control module 31, and the other two electrodes are connected in parallel with the resistor R and then connected in series with the energy storage element 34. After the energy storage element 34 is charged with the first current to reach the preset condition, the control module 31 outputs a control signal to control the semiconductor switch Q1 to be turned on, so as to short-circuit the resistor R, and thus the energy storage element 34 is directly connected in parallel to two ends of the driving circuit 32 for filtering.

Referring to fig. 5, as another specific embodiment, the switching element 351 is a relay J, a control coil of the relay J is electrically connected to the control module 31, specifically, the control coil of the relay J is electrically connected to a power module (not shown) in the control module 31, and the control module 31 can control the energization state of the control coil of the relay J by controlling an electronic switch (not shown). After the energy storage element 34 is charged with the first current to reach the preset condition, the control module 31 outputs a control signal to control the control coil of the relay J to be electrified, so that the resistor R is short-circuited, and the energy storage element 34 is directly connected to two ends of the driving circuit 32 in parallel for filtering the driving circuit 32.

Referring to fig. 3 and 5, as another embodiment, the control module 31 is triggered by a trigger signal input by a user to output a control signal to the switching element 351, so that the switching element 351 is turned on, and the current limiting element 352 is short-circuited, so that the energy storage element 34 can be directly connected in parallel to two ends of the driving circuit 32 for filtering the driving circuit 32.

In the present embodiment, based on the structural characteristics of the electric power tool such as a lawn mower, the installation position of the battery pack 20 is far away from the position of an operating mechanism (e.g., a trigger) for starting the electric power tool 10, and the time from the insertion of the battery pack 20 by the user to the operation of the operating mechanism by the user is much longer than the time for charging the energy storage element 34, so that when the operating mechanism is operated by the user, the energy storage element 34 is already charged, and it is not necessary to detect the preset time elapsed from the turning on of the battery pack 20 and whether the voltage of the battery pack 20 is equal to the voltage of the energy storage element 34, and at this time, when the electric power tool 10 is started, the large current due to the charging of the capacitor does not occur, which may cause the generation of an electric spark at.

Specifically, the electric power tool 10 further includes: a trigger mechanism, operatively triggered to activate the motor 33, such as the aforementioned trigger 15; the signal switch K is connected with the trigger mechanism in a correlation manner and is electrically connected with the control module 31, and the signal switch K is triggered by the trigger mechanism to change the on-off state and is used for outputting a starting signal to the control module 31; the control module 31 is configured to: after the signal switch K outputs the enable signal, a first control signal is output to control the switching element 3521 to be turned on to short-circuit the current limiting element 3511. In this way, the energy storage element 34 is directly connected in parallel to both ends of the drive circuit 32, and can perform a filtering function on the drive circuit 32.

Alternatively, after the switching element 3521 is turned on, the control module 31 outputs a second control signal to the driving circuit 32 to start the motor 33. That is, after the energy storage element C is charged with the first current to reach the preset condition and the switch element 3521 is turned on to short-circuit the current limiting element 3511, the driving circuit 32 is operated, so that the energy storage element 34 can normally filter the power of the driving circuit 32.

Compared with the previous embodiment, the mode that the signal switch K triggers the control module 31 to output the control signal to the switching element 351 does not need the voltage detection circuit 36 to detect the voltage across the energy storage element 34, so that the circuit design is simpler and the cost is lower.

In this way, in the initial stage of mounting the battery pack 20 on the electric tool 10, the energy storage element is slowly charged through the current limiting element, so that the situation that electric sparks or switch contact damage is generated between the connecting terminal of the electric tool 10 and the connecting terminal of the battery pack 20 due to the fact that large current is generated at the moment when the electrolytic capacitor C is directly charged can be avoided; and after the charging of the electrolytic capacitor C reaches a preset condition, for example, a preset voltage threshold, a preset electric quantity threshold or a preset duration is reached, at this time, the current limiting element 3511 is short-circuited to connect the electrolytic capacitor C in parallel to two ends of the driving circuit 32 so as to normally filter the driving circuit 32, and the current limiting element 3511 does not continuously consume the electric quantity of the battery pack.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.