CN101941192A - Electric tool - Google Patents
Electric tool Download PDFInfo
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- CN101941192A CN101941192A CN2009101403314A CN200910140331A CN101941192A CN 101941192 A CN101941192 A CN 101941192A CN 2009101403314 A CN2009101403314 A CN 2009101403314A CN 200910140331 A CN200910140331 A CN 200910140331A CN 101941192 A CN101941192 A CN 101941192A
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- 230000008859 change Effects 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 5
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 4
- 229910052744 lithium Inorganic materials 0.000 claims description 4
- 230000000875 corresponding effect Effects 0.000 description 21
- 238000009795 derivation Methods 0.000 description 17
- 239000000463 material Substances 0.000 description 9
- 239000002023 wood Substances 0.000 description 8
- 230000001105 regulatory effect Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000005553 drilling Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000000844 transformation Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000011121 hardwood Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000007779 soft material Substances 0.000 description 1
- 239000011122 softwood Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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Abstract
The invention relates to an electric tool which comprises a casing, a motor, a power source, a working head, a control assembly and a control indicating device, wherein the motor is contained in the casing; the power source provides current for the motor; the working head is driven by the motor to rotate; the control assembly is positioned in the casing and automatically lowers the rotation speed of the motor according to the state change of the working head; the control indicating device is arranged on the casing and is electrically connected with the control assembly; and the control indicating device comprises an executive component capable of enabling the control assembly to be at least in an active first position and an inactive second position. Compared with the prior art, the invention enables an operator to definitely know the running state of the torsion control device of the electric tool to avoid the motor overload, thereby prolonging the service life of the motor and enabling the operation to be simple and convenient.
Description
Technical Field
The present invention relates to an electric tool, and more particularly, to an electric tool having an automatic torque control function.
Background
The existing electric tool, such as an electric screwdriver, supplies current through a loaded power supply to drive a motor to rotate, so that a working head is rotated to drill screws into a wood board. Different types of screws have different body diameters or different head shapes, and thus their drilling into the same wood board is different. In addition, different wood boards have different hardness due to different materials, so that the situation that the same screw drills into the wood boards with different materials is different. Typically, during use of the power screwdriver, the user drills the screw with the head proximate to the surface of the workpiece, and as such, the user needs to pay great care to the drilling process to control the motor to stall when the head of the screw is proximate to the surface of the workpiece. Thereby, on the one hand, the screw head is prevented from being drilled too deeply into the wood board, and on the other hand, the motor is prevented from being overloaded due to too much resistance after the screw head is drilled inadvertently into the wood board.
Typically, such power tools are provided with an overload protection device, such as a mechanical clutch, which disengages the working head of the power tool from the motor in the event of an overload of current. The electric tool using the overload protection device is usually provided with a torque cover at the front part of the casing, namely a rotatable cover marked with a plurality of torque gear scales indicating the working limit of the electric tool. When the torque output by the electric tool during working reaches or exceeds a preset threshold value, the clutch system can automatically start to work to enable the working head of the electric tool to be disengaged from the motor. The user can set the limit torque value of the electric tool operation by rotating the torque cover in advance. However, in practice, the user does not know what gear is set in advance to be appropriate, and the above problem still occurs.
The electronic clutch can also be arranged, the current or the torque of the motor is detected by the microprocessor, and when the working current of the electric tool reaches a certain preset current value, the microprocessor sends out a signal to reduce the rotating speed of the motor or stop the motor. When the electronic clutch is used as an overload protection device, if a punching operation is to be performed, the electronic clutch needs to be stopped. However, the operator cannot clearly know whether the electronic clutch of the electric power tool is activated, and thus, the operator is confused about the punching operation.
Disclosure of Invention
The invention provides an electric tool capable of indicating the torque control state of the tool.
In order to achieve the purpose, the technical scheme of the invention is as follows: an electric power tool comprising: the motor comprises a shell, a motor contained in the shell, a power supply for supplying current to the motor, a working head driven by the motor to rotate, a control component and a control indicating device, wherein the control component is positioned in the shell and used for automatically reducing the rotating speed of the motor according to the state change of the working head, the control indicating device is arranged on the shell and electrically connected with the control component, and the control indicating device comprises an operating element which enables the control component to be at least positioned at a first position where the control component is functional and a second position where the control component is not functional. The control indication device also comprises a display device for indicating that the operation element is positioned at the first position and the second position.
Compared with the prior art, the torque control device has the advantages that the torque of the tool is automatically controlled by additionally arranging the related electronic control assembly in the electric tool, and the specific control mode is represented by the display device, so that an operator can clearly know the running state of the torque control device of the electric tool, the motor overload is avoided, the service life of the motor is prolonged, and the operation is simple and convenient.
Preferably, the display device includes at least one LED lamp electrically connected to the operating element. The display device comprises two LED lamps. When the control assembly is in the first position, one of the LED lamps is turned on. When the control assembly is in the second position, another of the LED lights is turned on.
The operating element may be adapted to bring the control unit into an active third position.
Preferably, the operating element is a button.
The electric tool further comprises a switch electrically connected with the motor and the power supply respectively, and preferably, the switch is a speed regulation switch. When the switch is toggled, at least one of the LED lights is turned on; when the switch is turned off, the LED lamp is turned off instantaneously.
The electric tool is instantly connected with the power supply, and the LED lamp is turned on and kept for a period of time. The operating element is not able to switch the position of the control assembly when the motor is running.
Preferably, the control assembly comprises a sensor for measuring the motor current, an electronic control unit for detecting a pulse signal on a curve of the second derivative or the higher derivative of the current with respect to time and generating a control signal therefrom for reducing the motor speed. The control assembly comprises a microprocessor. The control component multiplies the value of the first derivative and the second derivative of the current with the time, a threshold value is preset for the value of the product, and when the product of the first derivative and the second derivative is a positive value and the value is larger than or equal to the threshold value, a corresponding control signal is generated to reduce the speed of the motor or stop the motor.
The control assembly comprises a memory device, and the memory device stores the position of the control assembly when the electric tool is shut down and transmits a corresponding signal to the control indicating device. And the display device displays the position of the control component stored in the memory device when the motor is connected with the power supply.
The electric tool comprises a speed regulating switch, when the speed regulating switch is located at a first position, the display device displays the position of the control component, and when the speed regulating switch is located at a second position, the operating element does not act on the control component.
Preferably, the electric tool is a direct current electric drill, and the power supply is a lithium battery pack.
Preferably, the control indication device is arranged on the housing at a position adjacent to the power supply. The battery pack power display device can be arranged at the same position with the battery pack power display device, and the battery pack power display device share one display screen, so that an operator can conveniently observe the battery pack power display device.
Drawings
The invention is further described with reference to the following figures and embodiments.
Fig. 1 is a perspective view of the power tool of the present invention.
Fig. 2 is a schematic view of a first embodiment of the control indicating device of the electric power tool of the present invention.
Fig. 3a is a schematic view of a second embodiment of the control and indication device of the power tool of the present invention.
Fig. 3b is a schematic view of a third embodiment of the control and indication device of the power tool of the present invention.
Fig. 3c is a schematic view of a fourth embodiment of the control and indication device of the power tool of the present invention.
Fig. 3d is a schematic view of a fifth embodiment of the control and indication device of the power tool of the present invention.
Fig. 4 is a functional block diagram of a control assembly of the power tool of the present invention.
Fig. 5 is a block diagram of another operational principle of the control assembly of the power tool of the present invention.
Fig. 6 is a block diagram of another operational principle of the control assembly of the power tool of the present invention.
Fig. 7 is a block diagram of a control circuit of the electric power tool of the present invention.
Wherein,
Workhead 8 chuck 10 clutch system 12
Screw 14 plank 16 power supply 18
Switch 20 control assembly 22 sensor 24
Stored in the processing unit 32, the electronic control unit 42 of the third derivation unit 34
Control indicating device 50L 1-L9LED Lamp operating element 52, 52a, 52b, KEY1
Detailed Description
The electric screwdriver 2 shown in fig. 1 includes: the device comprises a machine shell 4, a motor 6 accommodated in the machine shell 4, a power supply 18 for supplying current to the motor 6, a working head 8 driven by the motor 6 to rotate, a control assembly 22 positioned in the machine shell 4 and used for automatically reducing the rotating speed of the motor 6 according to the state change of the working head 8, and a control indicating device 50 arranged on the machine shell 4 and electrically connected with the control assembly 22. The electric screwdriver 2 further comprises a switch 20 for controlling whether the electric motor 6 is powered. The motor 6 drives the working head 8 to rotate to drill the screws 14 into the wooden board 16. The motor 6 is connected with the working head 8 through a mechanical spring, and the clutch system 12 and the chuck 10 are connected with each other.
In this embodiment, the power source 18 is a dc power source or a rechargeable battery that supplies dc power to the motor 6 when the switch 20 is closed. Preferably, the power source 18 is a lithium battery pack. Of course, those skilled in the art can easily think of the alternative current power supply instead of the direct current power supply in the present embodiment.
The control and indication device 50 includes an operating member 52 for placing the control assembly 22 in at least a first position in which it is active and a second position in which the control assembly 22 is inactive, and a display device 54 for indicating the first and second positions of the operating member 52. The operating element 52 may also place the control assembly 22 in an active third position, and correspondingly, the display device 54 may also indicate that the operating element 52 is in this third position. The display device 54 includes at least one LED lamp electrically connected to the operating element 52. When the control assembly 22 is in the first position, at least one LED light is on.
In the present invention, the control assembly 22 comprises a sensor 24 for measuring the current of the electric motor 6, an electronic control unit 42 for detecting a pulse signal on a curve of the current over time in the second or higher derivative and for generating therefrom a control signal for reducing the speed of the electric motor 6. Preferably, the control assembly 22 includes a microprocessor. In the present embodiment, the electric tool is a dc electric screwdriver, and the power source 18 is a lithium battery pack.
The control indication device 50 is disposed on the housing 4 and electrically connected to the control component 22. The control and indication device 50 includes a control panel for housing an operating element 52 and a display device 54.
See the specific embodiment of the control and indication device 50 shown in fig. 2-3 d. In the first embodiment of the control and indication device shown in fig. 2, the operating element 52a is a toggle button disposed on the top of the housing 4 and electrically connected to the control assembly 22. The operating element 52a is movable in a direction of longitudinal extension of the casing 4 so as to switch the control member 22 between an active first position (ON) and an inactive second position (OFF). Of course, the operating element 52 can also be a knob, which is rotated about an axis fixedly arranged on the housing 4, and which likewise can bring the control assembly 22 into at least the two positions mentioned above.
In the embodiment shown in fig. 3a-3d, the operating element 52b is a push button that can be pressed by the operator in different activation states. Preferably, the display device 54 is provided on the same control panel as the operating elements 52 b. Of course, it is also easily conceivable by the person skilled in the art to arrange the operating element 52 on the housing 4 in a location which is easy to operate by the operator, while the display device 54 is arranged in a different position, but which is easy to observe and see by the operator. For example, buttons are provided on the housing adjacent the tool operating handle, and the display device is mounted on a portion of the housing adjacent the dc power source. It is even conceivable to locate the display device 54 at the same location as the display device that displays the power level of the battery pack.
Referring to the embodiment shown in fig. 3a, the display device 54 comprises two LED lamps. The combination of the turning off and turning on of the LED lamp corresponds to three states of the control assembly 22. The LED light L1 is on and L2 is off, indicating that the control assembly 22 is in a torque adjustment mode where a screw is screwed through a harder material, with the control assembly 22 in the first active position. L1 is closed and L2 is open indicating that the control unit 22 is in a torque adjustment mode for threading small screws through the softer material, with the control unit 22 in a second active position. L1 and L2 are both closed indicating that the control unit 22 is in an inoperative position, in which the electric screwdriver 2 does not perform the operation of screwing the screw 14 and is only available for drilling. In accordance with this embodiment, the LED lamp as the display device may be marked with H (Hard wood) and S (Soft wood) correspondingly so that the operator can distinguish between different working modes.
Or still the upper two LED lamps. L1 is open, L2 is closed indicating that the control module is in the active position, L1 is closed, and L2 is open indicating that the control module is in the inactive position. Corresponding to this embodiment, the LED lamp as display means may be provided with corresponding marks ON and OFF to allow the operator to confirm whether the control assembly is in the active position.
In the embodiment shown in fig. 3b, there is only one LED light, and the turning on and off of L3 corresponds to the turning on and off of control assembly 22. That is, when L3 is open, the power screwdriver 2 can be used to drive screws with the control assembly in the first, active position, and when L3 is closed, the control assembly is in the second, inactive position, and the power screwdriver is used only for drilling.
In the embodiment shown in fig. 3c, there are at least two LED lamps. L4 is green light, L5 is red light. L4 is open when operating element 52b places control assembly 22 in the active position. L5 is open when the operating element 52b has placed the control assembly 22 in the inoperative position. Under the condition that the electric screwdriver 2 is not started, the L4 and the L5 are both in a closed state. Once the electric screwdriver 2 is turned on, similar to the embodiment of fig. 3a, at least one of L4 and L5 is in the open state to indicate the operating state of the control assembly 22. If the control assembly 22 can be in two operative positions, correspondingly, there can be three LED lights, L6 being a yellow light. In this embodiment, the L4 lamp is on and L5 and L6 are off, corresponding to a torque adjustment mode of screwing a large screw onto a harder material, with the control assembly 22 in an active position. The L6 lamp is on and L4 and L5 are off, corresponding to a torque adjustment mode of screwing a small screw over a softer material, with the control assembly 22 in another position of operation. Whereas L5 is open and L4 and L6 are closed, corresponding to the state in which the automatic torque adjustment mode is off, i.e., the control unit 22 is in the inoperative position.
To facilitate operator recognition of the mode of operation in which the tool is located, on the control panel, each LED light may be labeled H, S, and OFF, respectively, to indicate a mode of operation on harder materials (Hard), a mode of operation on softer materials (Soft), and a mode of operation in which the control assembly is not active (OFF).
As shown in fig. 3d, the control and indication device 50 may include an LCD screen as a display device, and the different torque adjustment positions are directly displayed by specific characters. Such as automatic torque adjustment mode on and automatic torque adjustment mode off. Icons for a large screw and a small screw may also be fixedly provided on the display screen to indicate to the control assembly 22 whether it is in the Hard material or large screw mode (Hard) and Soft material or small screw mode (Soft), respectively. The display screen can also display the electric quantity of the battery pack at the same time, and as shown in the figure, a plurality of grids which are increased step by step are adopted to represent the electric quantity. When the electric quantity of the battery pack is sufficient, all seven grids are bright, and when the electric quantity of the battery pack is insufficient, only one grid is bright. And the other states correspond to the electric quantity by the number of the squares. Of course, other display devices, such as a multi-bit nixie tube, etc., can be easily conceived by those skilled in the art, and are not described herein in detail by the applicant.
Referring to fig. 4, the control assembly 22 for automatically reducing the motor speed in response to a change in the state of the working head includes an electronic control unit 42 and a sensor 24 for detecting the current, connected between the power source 18 and the motor 6. The state change of the working head refers to the situation that whether the working head is abutted to the surface of a workpiece by a screw head in the rotating process or not so that the load is increased rapidly. Under normal state, the screw is screwed into the wood by the working head, the load born by the working head is relatively stable, and the current of the corresponding motor is relatively stable. When the screw head abuts the surface of the workpiece, the load on the work head increases momentarily, at which point the control assembly 22 senses the motor current and adjusts the motor speed accordingly, such as by cutting off the motor current, causing the motor speed to decrease until the machine is shut down. In the present embodiment, the electric screwdriver 2 further includes a first derivation means 26 and a second derivation means 28. The sensor 24 will detect the current i supplied to the motor 6 in real time and at the same time generate a signal proportional to the detected current and transmit it to the first derivation unit 26; then the first derivation unit 26 calculates the first derivative di/dt according to the current and time, and generates a signal proportional to the first derivative and further transmits the signal to the second derivation unit 28; subsequently, the second derivation unit 28 derives a second derivative, and generates the control signal s when the peak signal p is a positive value and numerically greater than a preset threshold value v when a preset condition is generated. In the present embodiment, the control signal s is used to reduce the rotation speed of the motor 6 or to interrupt the supply of electric power to the motor 6. That is, the control signal s is used to reduce the current i supplied to the motor 6 to a lower level or to zero, thereby reducing the rotational speed of the motor 6 or stalling the motor. Of course, the control signal s can also be used to change the direction of the current i, so that the motor 6 can be stopped quickly. In the present embodiment, the control signal s is transmitted to the electronic control device 42, and then the electronic control device 42 executes corresponding actions, which actions may be generated immediately after the generation of the peak signal p, or may be generated after a delay period, where the delay may be implemented in the electronic control device 42, or may be implemented by a separately provided delay unit.
In a preferred embodiment, the control unit 22 may comprise a microprocessor, and the functions implemented by the first derivation unit 26, the second derivation unit 28, or a delay unit if present, may be implemented by instructions that are resident in the microprocessor. That is, the entire control assembly 22 may be a microprocessor.
The above embodiment automatically detects whether the work piece driven by the working head 8 reaches the preset position by adding the related electronic control assembly 22 in the electric tool, and executes corresponding action after detecting that the work piece reaches the preset position, so as to ensure that the work piece cannot further cross the preset position.
The power tool 2, for example a power screwdriver, shown in fig. 5, operates using the above-described embodiment based on the second operating principle. Most of the elements are the same or similar to the embodiment shown in fig. 4, so the same reference numerals are used for these elements.
The working assembly 4 of the electric screwdriver shown in fig. 5 comprises a dc motor 6 for driving a working head 8 held on a tool holder 10. The tool holder 10 and the motor 6 are connected to the clutch system 12 by a mechanical spring. The working head 8 is used to rotate a screw 14 to screw it into the board 16. The power source 18 is a dc power source, which may be a rechargeable battery, that supplies a dc current i to the motor 6 when the trigger switch 20 is closed.
An electronic control unit 42 and a sensor 24 for detecting the current are connected between the power source 18 and the motor 6. The current sensor 24 will sense the current supplied to the motor in real time and generate a signal proportional to the sensed current and pass it to the derivation unit 26. The derivation unit 26 then generates a signal proportional to the first derivative of the current with respect to time di/dt. The output of the derivation unit 26 is connected to an input of a storage and processing unit 32.
The storage and processing unit 32 has stored therein, as described above in the first embodiment, a single threshold value P1 and first and second first derivative values q1 and q 2. At a preset time point T1, if the current i1 is lower than the threshold P1, the storing and processing unit 32 selects a first derivative value q 1; if the current i2 is above the threshold P1, the storage and processing unit 32 selects the second first derivative value q 2. Wherein the second derivative value q2 is greater than the first derivative value q 1. When the first derivative di/dt reaches the first or second preset first derivative value q1 or q2, the control signal s1 or s2 is generated in response to the processing unit 32. At this point, the screw heads have reached the surface of the plank. The storage and processing unit 32 transmits the control signal s1 or s2 to the electronic control unit 42. The electronic control unit 42 is used to reduce or cut off the power supplied to the motor 6. That is, the control signal s1 or s2 is used to reduce the current i supplied to the motor to zero or a lower value to cause the motor to stall or rotate at substantially zero speed. In the present embodiment, the control signal s is used for this purpose by the electronic control circuit 30. The deceleration control of the motor may be performed immediately after the generation of the pulse signal p or may be performed after a certain time delay. The control signal s1 or s2 can also be used to change the direction of the current i, thereby causing the motor to stall rapidly.
Fig. 6 shows a third embodiment of the control assembly 22 of the present invention for reducing the rotational speed of the power tool 2 by using a third derivative of the current with respect to time.
In particular embodiments, at the second derivative d2i/dt2On the basis of (1), further finding out the third derivative d of the current to the time3i/dt3. If a third derivative value d is detected3i/dt3Above a predetermined threshold value v1 and positive, a control signal s is generated. The control signal s is then used to reduce the rotational speed of the electric screwdriver 2.
The generation of the control signal s is achieved by detecting a derivative of fourth, fifth or higher order, as known to the person skilled in the art. Since these are easily inferred, the applicant is not described herein in detail.
It is noted that the signal output by the second derivation unit 28 is passed to the third derivation unit 34, and then the third derivative d is generated3i/dt3. As the third derivation unit 34 outputs a signal, a positive pulse value p1 is input to the electronic control circuit 30, which is regarded as the control signal s. The control signal s causes the direct current i supplied to the motor 6 to be reduced or even completely cut off by the electronic control circuit 30.
The first, second or higher order derivatives mentioned in the above embodiments are not limited to the purely mathematical definition of derivatives, but may also include simple equivalent transformations based on the principle of derivatives in practical engineering applications. For example, the first derivative may also be expressed as a change in current Δ i over successive time intervals Δ t, i.e., Δ i/Δ t. For engineering application convenience, Δ t may be a very small equivalent value, for example, Δ t is 10ms, so that the operation equivalent to the first derivative calculation can be implemented only by continuously judging the difference of the current i. By analogy, similar equivalent transformations to the second derivative or higher derivatives are included within the meaning of derivatives in the present invention.
Another embodiment of generating the control signal based on a second or higher order derivative will be discussed below. Taking the second derivative as an example, the electric screwdriver sometimes encounters some abnormal conditions during operation, which causes abnormal sudden changes of the operating current, so that the obtained second derivative is interfered. Such as when the screw encounters a knot in the board during screwing into the board, resulting in a sudden increase in current; or when the current suddenly and greatly rises just after the motor is started and the motor does not enter a stationary period, the detection is carried out; or when the direct-current battery pack is used as a power supply, the voltage of the battery pack is rapidly reduced due to over-discharge, so that the current is suddenly changed; or sudden arm vibration of the user during the use process, which causes sudden current change. If the screw is not fully screwed into the plank when this occurs, the second derivative calculated from the current with respect to time may interfere, i.e. the second derivative generated may also reach or exceed the preset threshold value v, and the control assembly, the electronic control unit 42, may erroneously assume that the screw has been fully screwed into the plank and cut off the power to the motor, which is obviously undesirable for the user.
In order to solve the above problem, the control component may multiply the value of the second derivative by a corresponding current value (i.e., a value of the second derivative calculated based on the current value) and preset a new threshold for the multiplied value, and generate a corresponding control signal to reduce the speed or stop the motor when the product of the second derivative and the corresponding current is a positive value and the value is greater than or equal to the new threshold. It is clear that the new threshold value is much larger than the original threshold value v, in such a way that the difference between the actually desired second derivative and the disturbing second derivative is enlarged, so that the actually desired second derivative is screened out using a larger threshold value. Of course, in other embodiments, the product of the current or the first derivative or the second derivative with a fixed constant, the nth power of the current or the first derivative or the second derivative, the product of the current with the corresponding first derivative, the product of the second derivative with the corresponding first derivative and the current, and the sum of the first derivative or the second derivative and a value close to 90, and then the tangent function value (such as tan (89+ first derivative or second derivative)), the cotangent function value of the first derivative or the second derivative (such as ctan (first derivative or second derivative)), or the logarithmic function value (such as loga (1-first derivative or second derivative)) with any value a as the base and the difference between the value 1 and the first derivative or the second derivative as the true value can be compared with the corresponding threshold value, when the value is greater than or equal to the corresponding threshold value (the value is a positive number) in the value (i.e. the absolute value), a control signal is generated to reduce the speed or stop the motor.
Referring to fig. 7, a block circuit diagram of the power tool of the present invention is shown. Wherein the display device is two LED lamps and the operation element is a control switch KEY 1. After the electric tool is matched and connected with the battery pack, the battery pack provides 5V voltage for the MCU through the VCC, the MCU is powered on, the program runs, and one LED lamp in the display device electrically connected with the control circuit can be lightened. The control assembly 22 includes a memory device that stores the position of the control assembly 22 when the power tool is turned off and transmits a corresponding signal to the control indicating device 50. The display device 54 displays the position of the control component stored in the memory device when the motor 6 is connected to the power source 18. In this embodiment, the MCU stores the position of the control component when the power is turned off or interrupted last time. If the control assembly 22 was in the active position the last time it was shut down, then the corresponding L1 light is on; if the control assembly 22 was in the inoperative position the last time it was shut down, the corresponding L2 light is on at this time. The operator can switch the control assembly between the active position and the inactive position by pressing the operating element KEY1, as desired, the corresponding LED lamp being alternately illuminated.
After the LED lamp is turned on, if the operator does not pull the main switch 20 of the power tool, in order to save the power in the battery pack, after a certain period of time, for example, 10 minutes, the MCU will turn off the LED lamp, and at the same time, the whole system enters a sleep state. If the operator pulls the main switch 20 to rotate the motor, the display device will always be on. At this time, the operating element KEY1 is pressed again, and the state of the control assembly cannot be changed. That is, when the motor of the electric tool is in the operating state, the state change mode transition of the control assembly is masked. That is, if the power tool is coupled with the battery pack, the main switch 20 is closed, and the motor 6 is driven to rotate, the operation element does not function. Therefore, the situation that an operator forcibly switches the position of the control assembly due to misoperation in the using process to cause unnecessary working conditions, such as screwing the screw head into wood, can be prevented.
However, the operator does not frequently insert and remove the battery pack to confirm whether the control unit is functioning. Therefore, it is more common that the battery pack and the power tool are mated together, but the display device, i.e., the LED light, is not illuminated in order to conserve power in the battery pack. It is therefore desirable to design a switch that allows the operator to easily confirm the status of the control assembly without wasting battery power. Thus, the main switch 20 of the power tool may be a speed regulating switch. When the speed regulating switch is in the first position, the display device displays the position of the control component, and when the speed regulating switch is in the second position, the operating element does not act on the control component. When an operator lightly presses the LED lamp, the LED lamp of the display device is instantly turned on, but the motor does not rotate, the operator knows the state of the control assembly when the control assembly is turned off last time, and then selects whether the position of the control assembly needs to be changed or not according to needs.
In another situation, the battery pack is plugged with the electric tool, but the electric quantity in the battery pack is extremely low, which is not enough to drive the motor to operate, and at this time, the display device, i.e. the LED lamp, is not bright. The LED lamp is in a closed state no matter whether an operator pulls the main switch or not. In order to indicate that the power tool is in a state where the battery pack is low but the control assembly can function, a power display device may be separately provided. The LED lamp L7 shows that the battery pack is high in power, the battery pack is medium in power L8, and the battery pack is low in power L9. When the electric quantity of battery package was not enough to drive the motor operation, electric quantity display L9 lamp scintillation reminded the user to consider earlier and change the battery package.
In the case of the power tool having the battery pack power display device, the display device of the control and indication device 50 may share a display panel with the power display device, and be disposed at a position adjacent to the housing of the battery pack.
The above description is made by taking an electric screwdriver as an example, but the present invention may be applied to other electric tools such as an electric drill and an electric wrench. Since such an application can be easily implemented by the above-described embodiments by those of ordinary skill in the art, detailed description thereof will not be provided herein.
Claims (10)
1. A power tool, comprising:
a machine shell, a first cover plate and a second cover plate,
a motor accommodated in the casing,
a power supply for supplying a current to the motor,
a working head driven by a motor to rotate,
a control component which is positioned in the machine shell and can automatically reduce the rotating speed of the motor according to the state change of the working head,
the method is characterized in that:
a control indicating device disposed on the housing and electrically connected to the control assembly includes an operating member for causing the control assembly to assume at least a first position in which the control assembly is active and a second position in which the control assembly is inactive.
2. The power tool of claim 1, wherein: the control indication device also comprises a display device for indicating that the operation element is positioned at the first position and the second position.
3. The power tool of claim 2, wherein: the display device comprises at least one LED lamp electrically connected with the operating element.
4. The power tool of claim 3, wherein: the display device comprises two LED lamps.
5. The power tool of claim 4, wherein: when the control assembly is in the first position, one of the LED lamps is turned on.
6. The power tool of claim 1, wherein: the control assembly comprises a memory device, and the memory device stores the position of the control assembly when the electric tool is shut down and transmits a corresponding signal to the control indicating device.
7. The power tool of claim 1, wherein: the operating element is a button.
8. The power tool of claim 1, wherein: the control assembly includes a sensor for measuring the motor current, an electronic control unit for detecting a pulse signal on a curve of the current over time for a second or higher derivative and for generating a control signal therefrom for reducing the motor speed.
9. The power tool of claim 8, wherein: the control assembly comprises a microprocessor.
10. The power tool of claim 9, wherein: the electric tool is a direct current electric drill, and the power supply is a lithium battery pack.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101403314A CN101941192B (en) | 2009-07-10 | 2009-07-10 | Electric tool |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101403314A CN101941192B (en) | 2009-07-10 | 2009-07-10 | Electric tool |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101941192A true CN101941192A (en) | 2011-01-12 |
| CN101941192B CN101941192B (en) | 2012-11-21 |
Family
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009101403314A Expired - Fee Related CN101941192B (en) | 2009-07-10 | 2009-07-10 | Electric tool |
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| Country | Link |
|---|---|
| CN (1) | CN101941192B (en) |
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| CN103386665A (en) * | 2012-05-07 | 2013-11-13 | 苏州宝时得电动工具有限公司 | Control method of electric tool and electric tool used for executing control method |
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| CN2144312Y (en) * | 1992-09-06 | 1993-10-20 | 郭德柱 | Multifunctional miniature electric tool |
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