CN201405335Y - Electric tool - Google Patents
Electric tool Download PDFInfo
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- CN201405335Y CN201405335Y CN200920038393XU CN200920038393U CN201405335Y CN 201405335 Y CN201405335 Y CN 201405335Y CN 200920038393X U CN200920038393X U CN 200920038393XU CN 200920038393 U CN200920038393 U CN 200920038393U CN 201405335 Y CN201405335 Y CN 201405335Y
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Abstract
The utility model relates to an electric tool, which comprises: an electric motor which is used for driving a working head to rotate and is provided with a rotating speed; an electric power source forsupplying an electric current to the electric motor; a sensor for measuring the electric current; and a control assembly for detecting the time change rate of the electric current so as to generate acontrol signal to reduce the rotating speed of the electric tool. The utility model can automatically detect whether the work pieces driven by the working head reach a preset position or not throughadditionally adding the relative electronic control assembly in the electric tool, and processes the corresponding action after detecting that the work pieces reach the preset position so as to guarantee that the work pieces cannot further cross the preset position.
Description
Technical field
The utility model relates to a kind of electric tool, relates in particular to a kind of electric screw driver.
Background technology
Existing electric tool as electric screw driver, provides electric current by the power supply that loads, and comes drive motors to rotate, thereby makes the working head rotation so that screw is crept in the plank.Dissimilar screws has different main diameters, perhaps has different nose shapes, and so, its situation of creeping in the same plank also has nothing in common with each other.In addition, different planks is because the material difference makes its hardness also different, and so, the situation that same screw creeps in the plank of unlike material also is not quite similar.Usually in the use of electric screw driver, the user need be drilled into screw the surface that head is pressed close to workpiece, and so, the user need pay close attention to drilling process very carefully, controls the motor stall when pressing close to workpiece surperficial when the head of screw.Thereby, on the one hand avoid screw head to be pierced plank inside too far, avoid screw head to be crept into plank because of carelessness on the other hand after, owing to suffering excessive resistance to make motor overload.
Common this electric tool can be provided with overload protection arrangement.This overload protection arrangement can be a kind of mechanical clutch, can under the situation of above-mentioned current overload the working head of electric tool be cooperated with the motor disengaging.Adopt the electric tool of this overload protection arrangement can be provided with a torsion cover, i.e. a rotatable cover that indicates some scales simultaneously in the front portion of its casing usually.These scales are represented the limit torsion gear of electric tool work.When using, the user can set the limit torque value of electric tool work in advance by the rotary torsion cover, that is to say, when the torsional moment of exporting in the electric tool work met or exceeded this predefined threshold values, clutch system can be started working automatically and be made the working head of electric tool and motor break away from cooperation.In addition, the electric screw driver that adopts this overload protection arrangement also can be that the front end at its casing extends a sleeve pipe, and the front end of the front end of this sleeve pipe and the working head of electric screw driver remains basically stable.Pass through this set, when its head that gets into when screw was attached to plank surperficial, the leading section of sleeve pipe also was attached to the surface of plank, further bores moving screw again, sleeve pipe can be subjected to compressing of plank and make it touch the interior clutch mechanism of casing, cooperates thereby working head and motor are broken away from.Yet above-mentioned mechanical clutch structure is all comparatively complicated, makes trouble, and cost is higher.
The utility model content
The utility model provides a kind of electric tool, and it has Electronic Control Unit, and the work package that can avoid being driven by working head is further crossed this position after arriving the precalculated position.
One of for achieving the above object, the technical solution of the utility model is:
A kind of electric tool, it comprises:
Output shaft is used to drive a working head, so that working head has a rotary speed;
Motor, rotation drives described output shaft;
Power supply is used to supply with described motor electric power;
Sensor is used to measure the parameter of expression output shaft load;
Control Component is used for
Obtain second dervative or the higher derivative of described parameter to the time;
Generate control signal corresponding to change the rotary speed of described motor according to described second dervative or higher derivative.
Compared with prior art, the utility model comes the work package of automatic testing head driving whether to arrive the precalculated position by set up relevant Electronic Control Unit in electric tool, and carry out corresponding actions after this work package arrives precalculated position detecting, guarantee that it can further not cross this precalculated position.And, owing to do not adopt complicated mechanical formula clutch configuration, making and make simply, cost reduces.
Description of drawings
The utility model is described in further detail below in conjunction with drawings and embodiments.
Electric current and time relation curve map when Fig. 1 is the work of existing electric screw driver.
Fig. 2 is the derivative curve figure of electric current after to a time differentiate among Fig. 1.
Fig. 3 is the derivative curve figure of electric current after to time secondary differentiate among Fig. 1.
Fig. 4 is the operation principle block diagram of electric tool of the present utility model based on the first utility model principle.
Electric current and time relation curve map when Fig. 5 is electronic screw to work, two different current i 1 when wherein having represented the different operative scenario of two kinds of correspondences, the curve of i2.
Fig. 6 is different current i 1 among Fig. 5, the i2 derivative curve figure after to a time differentiate.
Fig. 7 is the control signal s1 that the first derivative of time is obtained according to different current i 1 among Fig. 6, i2, the curve map of s2.
Fig. 8 is the operation principle block diagram of electric tool of the present utility model based on the second utility model principle.
Fig. 9 is similar to Fig. 3, is the operating current of the electric screw driver derivative curve figure after to time secondary differentiate.
Figure 10 is the derivative curve figure of electric current after to time three differentiates among Fig. 9.
Figure 11 is the operation principle block diagram of electric tool of the present utility model based on the 3rd utility model principle.
Figure 12 is the cross-sectional schematic of another embodiment of electric tool of the present utility model.
Figure 13 is a partial enlarged drawing among Figure 12.
Figure 14 is the schematic perspective view of blanking disc among Figure 13.
Figure 15 is the schematic perspective view of another embodiment of blanking disc among Figure 13.
The specific embodiment
Control method of the present utility model can be applicable to polytype electric tool, below mainly is that the specific embodiment describes with the electric screw driver.
Electric current curve map over time during the work of as shown in Figure 1 electric screw driver.Cooperate with reference to shown in Figure 4, this electric screw driver 2 is pushed to order about work package 14 by the user, and this work package is a screw in the present embodiment, pierces in the plank 16.User's pressing force is basically near a constant.Wherein alphabetical t represents that screw pierces the time of plank and screw corresponding position in plank thereupon.Letter i represents to offer the electric current and the corresponding thereupon load or the driving force that is carried on the motor of the motor of electric screw driver.
Curve among Fig. 1 comprises the A of first, second portion K and third part B.Wherein the A of first is one section ascending curve, and the main part of its expression screw pierces the drilling process of plank, and this section ascending curve is linear basically, perhaps some bending and setback a little.The second portion K that follows hard on the A of first may also be referred to as flex point part (knee) K.This flex point Partial K is the curvilinear motion of a forward, that is to say, the flex point Partial K has acclivitous sudden change with respect to the A of first, and the head of this expression screw begins to touch the surface of plank.That follow the flex point Partial K closely is third part B, and it is one section equally is linear basically, perhaps can be a little some ascending curve crooked and setback.But curve B is much more precipitous than curve A.
In fact; curve among Fig. 1 is represented is the working condition of not using the electric tool that control method of the present utility model protects, so the third part B of curve represents that electric tool can produce very high electric current and caused the head of screw is pierced in the plank this moment.Therefore, be necessary that the situation of taking measures necessary to avoid above-mentioned generation excessive current takes place after the flex point Partial K.
When screw is drilled into the position corresponding with the flex point Partial K, continues the process that pierces the head of screw is pierced in the plank, and may damage motor.So the utility model is based on automatic detection flex point Partial K, after detecting, take corresponding precautionary measures then automatically.
Fig. 2 and Fig. 3 will explain how to detect the flex point Partial K in the present embodiment.
Fig. 2 is that current i is asked curve map behind the first derivative di/dt to time t among Fig. 1.Wherein, A of first among Fig. 1 and second portion B be the corresponding straight line that is parallel to horizontal axis t that is shown as on this figure, and second portion K then is shown as a curve that rises rapidly.
Fig. 2 is that current i is asked second dervative d to time t among Fig. 1
2I/dt
2After curve map.Wherein, A of first among Fig. 1 and second portion B be numerical value vanishing after the secondary differentiate, second portion K then is shown as the parabola that Open Side Down, and forms a peak signal p in parabolical top area (comprising the parabola summit between an interior given zone).Cooperate with reference to shown in Figure 4, when this peak signal p forms, can produce a control signal s thereupon.Certainly, in preferred embodiment, can preestablish a threshold values v, this control signal s only when peak signal p on the occasion of and numerical value on produce during greater than default threshold values v.For what those of ordinary skill in the art can expect easily be, this control signal s also can produce after current i is to time t differentiate for the first time, as the mode by capacitor, promptly produces control signal s when detecting first derivative after greater than a predetermined threshold values.
Shown in Figure 4 is the electric tool of the above-mentioned control method of application of the present utility model, below still is that example describes with the electric screw driver.Electric screw driver 2 comprises work package 4, power supply 18 and switch 20.Wherein work package 4 comprises motor 6, is used to drive a working head 8 rotations, so that a screw 14 is crept in the plank 16.Motor 6 is to being connected with a clutch system 12 and a chuck 10 by a mechanical type spring successively between the working head 14.Certainly in the present embodiment, clutch system also can save.In the present embodiment, power supply 18 is dc sources, or rechargeable battery, can supply with motor 6 direct currents when switch 20 closures.Certainly, those of ordinary skill in the art also can expect easily, adopts the dc source in the alternative present embodiment of AC power.
Be connected with electronic-controlled installation 22 and the sensor 24 that is used to detect electric current between power supply 18 and the motor 6.This electric screw driver also comprises the one first differentiate unit 26 and the second differentiate unit 28.In the present embodiment, sensor 24 can detect the current i of supplying with motor in real time, generates with the proportional signal of detected electric current simultaneously and passes to the first differentiate unit 26; Then as shown in Figure 2 first derivative di/dt is tried to achieve according to electric current and time in the first differentiate unit 26, generates one simultaneously with the proportional signal of this first derivative and further pass to the second differentiate unit 28; Subsequently, second dervative is as shown in Figure 3 tried to achieve in the second differentiate unit 28, and when pre-conditioned generation, as noted above when peak signal p be on the occasion of and numerical value on during greater than default threshold values v, generate control signal s.In the present embodiment, this control signal s is used to reduce rotating speed of motor or interrupts providing electric power to motor.That is to say that the current i that control signal s is used to supply with motor is reduced to a lower level or reduces to zero, thereby reduces rotating speed of motor or make the motor stall.Certainly, this control signal s also can be used to change the flow direction of current i, thereby motor 6 can be stopped rapidly.In the present embodiment, control signal s can be passed to electronic-controlled installation 22, then carry out corresponding action by electronic-controlled installation 22, these actions can be to produce the instant generation in back at peak signal p, also can be to postpone to produce after a period of time, this delay can realize in electronic-controlled installation 22, also can realize by the delay cell of independent setting.
Electronic control circuit among Fig. 4 can comprise a transistor switch, is used for disconnecting the electric current of supplying with motor.
In preferred embodiment, electronic-controlled installation 22 can comprise a microprocessor, and the function that the above-mentioned first differentiate unit 26, the second differentiate unit 28 or the delay cell that may exist etc. are realized all can be carried out by the instruction that is solidificated in the microprocessor.That is to say that whole electronic-controlled installation 22 can be a microprocessor.
In other optional embodiments, the current i of supplying with motor 6 can record in continuous time interval Δ t, and these continuous time interval Δ t can be identical.Detected current i is digitized processing subsequently, asks electric current in two continuous time intervals to the first derivative di/dt of time respectively, then these two first derivatives relatively; If result relatively shows both (being equivalent to the secondary differentiate in the aforementioned embodiments) inequality basically, mean that promptly the head of screw has arrived the surface of plank 16, can generate above-mentioned control signal s with that.
Above-mentioned embodiment comes the work package of automatic testing head driving whether to arrive the precalculated position by set up relevant Electronic Control Unit in electric tool, and carry out corresponding actions after this work package arrives precalculated position detecting, guarantee that it can further not cross this precalculated position.
Shown in Fig. 5-8 is the second utility model principle of control method of the present utility model and electric tool, below can elaborate each embodiment based on this utility model principle.
The current i of shown in Figure 5 is motor is the change curve of t in time.In the present embodiment, the current i of this motor is an electric screw driver is supplied with motor when driving working head work a direct current.Detected two current curve A1 and A2 have been shown among the figure.Identical with the front detected and the electric current of processing motor is undertaken by the clock pulses principle, and this belongs to technology well-known to those skilled in the art, and the applicant repeats no more.Shown in Figure 6 is current curve A1 and A2 corresponding first derivative curve after a differentiate.First curve A 1 and relative workpiece than softwood matter, as plank, or less relatively screw is relevant; And second curve A 2 and the relative workpiece of softwood matter firmly, or relatively large screw is relevant.Which kind of situation no matter, to the detection of curve A 1 and A2 with handle and all can carry out in Control Component 22 (Fig. 8 shows), in the present embodiment, this Control Component can also comprise a microprocessor.
In first embodiment based on the second utility model principle, at a predefined time point T1, current of electric i1 is collected.In microprocessor, store one threshold values in advance, be called the first threshold values P1.This first threshold values P1 may be, for example, at the T1 time point, P1=5A (ampere).If this moment, i1＜5A meaned that present electric screw driver just plays screw on a softer plank; If this moment, i1＞5A meaned that present electric screw driver just plays screw on a harder plank.Cooperate with reference to shown in Figure 6, if i1＜5A, microprocessor will be assigned one first default first derivative values q1; If i1＜5A, microprocessor will assign one second default first derivative values q2.Above-mentioned first and second default first derivative values q1, the q2 are stored in the microprocessor in advance.First presets first derivative values q1 can be, for example, and q1=0.4A/s; The second default first derivative values q2 presets first derivative values q1 greater than first, can be, for example, q2=1A/s.That is to say, if motor current value i1 is lower than the first threshold values P1 when time point T1, the first default first derivative values q1 can be selected, otherwise, if motor current value i1 is higher than the first threshold values P1 when time point T1, the second default first derivative values q2 can be selected so.
In Fig. 6, the electric current of corresponding curve A 1 and A2 corresponding first derivative curve after a differentiate is shown as a1 and a2 respectively.
Can will be appreciated that the abrupt bend section of curve A 1 and A2, just flex point Partial K 1 and the K2 of curve A 1 and A2 in the corresponding diagram 5 of ascent stage rapidly of curve a1 and a2 among Fig. 6.The front was mentioned, and flex point Partial K 1 and K2 represent that the head of screw begins to touch the surface of plank.These flex point Partial K 1 and K2 are used to generate respectively control signal s1 and s2 (as shown in Figure 7) in microprocessor.As shown in Figure 6, default first derivative values q1, q2 lay respectively at the ascent stage rapidly of curve a1, a2.
As shown in Figure 7, when the first default first derivative values q1 was selecteed, when the first derivative values di/dt of current of electric reached q1, the first control signal s1 that be positioned at time point t1 this moment can be generated by microprocessor.If determined to select second curve A 2 according to the detection when the time point T1, reach second when presetting first derivative values q2 as first derivative values di/dt so, the second control signal s2 that is positioned at time point t2 just is generated.
According to the first control signal s1 or the second control signal s2 that generate, the rotating speed of the direct current generator of electric tool will reduce or even stall.
That is to say: when Preset Time point T1, for example when 1 second behind starter motor or 2 seconds, microprocessor reads current of electric i.If working head is Screw and/or workpiece is plank than softwood matter, and the operating current i of this moment is less relatively, and the time dependent curve of electric current is just as first curve A 1 among Fig. 5.The electric current that collects when time point T1 is first current i 1, can be about 3A, and microprocessor will select the first first derivative values q1 (being stored in wherein in advance) to come to compare with the first derivative di/dt of electric current to the time.So, when the value of di/dt reached q1, corresponding time point was t1, and the corresponding electric current of supplying with motor is l1, and at this moment, rotating speed of motor will be controlled and reduction of speed by the first control signal s1 that q1 triggered.If working head is big screw and/or workpiece is the plank of hard material, and the time dependent curve of electric current this moment is just as second curve A 2 among Fig. 5.So second current i 2 that collects when time point T1 can be higher than first current i 1, for example, and i2=7A.Therefore, microprocessor will be selected the second first derivative values q2 (being stored in wherein in advance) when Preset Time point T1.When the di/dt value on the a2 curve reached q2, corresponding time point was t2, and the corresponding electric current of supplying with motor is l2, and at this moment, the second control signal s2 that rotating speed of motor will be generated controls and reduction of speed.
In second embodiment based on the second utility model principle, the current of electric i when Preset Time point T1 equally can be collected.At this moment, microprocessor can judge whether the value of detected current i when T1 can be lower than the first default threshold values P1, current value i1 in for example above-mentioned embodiment, perhaps whether be higher than the first default threshold values P1, but be lower than the second default threshold values P2, the current value i2 in for example above-mentioned embodiment.If detected current value is i1, then first curve A 1 will be dispatched to a default first derivative values q1; If detected current value is i2, then second curve A 2 will be dispatched to a bigger default first derivative values q2.Next, just as the individual step of being mentioned in first embodiment, the first derivative di/dt that is positioned at flex point K1, K2 will be used by microprocessor once more and generate control signal corresponding s1, s2.
It should be noted that and have only a pre-set threshold value P1 to be used in the first embodiment, and in second embodiment, have two pre-set threshold value P1, P2 to be used.
This equally also can be applied in second embodiment: stone if working head is the material of very large screw and/or workpiece, microprocessor can use the 3rd threshold values P3 (as shown in Figure 5) and the 3rd first derivative values q3 (as shown in Figure 6) that preestablishes within it equally.Need to prove that these threshold values P1, P2, P3 and these first derivative values q1, q2, q3 are stored in the microprocessor in advance, be used for when Preset Time point T1, according to detected different current value i1, i2, i3 and waken up individually respectively.Certainly, visual situation is used more threshold values P and first derivative values q.
These threshold values P and first derivative values q obtain and are stored in the microprocessor in advance by a series of test (for example, the screw of test different size carries out work on the workpiece of unlike material or specification).
Electric tool 2 shown in Figure 8, for example electric screw driver has used above-mentioned embodiment based on the second utility model principle to carry out work.Wherein, most of elements are identical or close with embodiment shown in Figure 4, so, these elements are used identical label.
The work package 4 of the electric screw driver shown in the right side of Fig. 8 comprises direct current generator 6, is used for driving the working head 8 that is clamped on the hammer 10.Be connected with clutch system 12 by a mechanical type spring between hammer 10 and the motor 6.Working head 8 is used for rotating a screw 14 it is screwed into plank 16.Power supply 18 is dc sources, can be rechargeable battery, can supply with motor 6 DC current i when trigger 20 closures.
Be connected with electronic-controlled installation 22 and the sensor 24 that is used to detect electric current between power supply 18 and the motor 6.Current sensor 24 can detect the electric current of supplying with motor in real time, generates with the proportional signal of detected electric current simultaneously and passes to differentiate unit 26.Differentiate unit 26 generate subsequently one with electric current to the proportional signal of the first derivative di/dt of time.The output of differentiate unit 26 is connected to the input of a storage and processing unit 32.
Store in storage and the processing unit 32, described in above-mentioned first embodiment, the single threshold values P1 and first and second first derivative values q1 and the q2.At Preset Time point T1, if current i 1 is lower than threshold values P1, storage is selected the first first derivative values q1 with processing unit 32; If current i 2 is higher than threshold values P1, then storage is selected the second first derivative values q2 with processing unit 32.Wherein the second first derivative values q2 is greater than the first first derivative values q1.When the first derivative di/dt reaches the first or second default first derivative values q1 or q2, storage and processing unit 32 corresponding generation control signal s1 or s2.At this moment, screw head has arrived the surface of plank.Storage passes to electronic-controlled installation 22 with processing unit 32 with control signal s1 or s2.This electronic-controlled installation 22 is used to reduce or disconnect the electric power of supplying with motor 6.That is to say, control signal s1 or s2 be used to make the current i of supplying with motor be reduced to zero or lower value so that motor stall or rotating speed be substantially zero.In the present embodiment, control signal s achieves this end by electronic control circuit 30.Reduction of speed control to motor can produce the instant execution in back at pulse signal p, also can be to delay the specific time to carry out.Control signal s1 or s2 also can be used for changing the flow direction of current i, thereby make the rapid stall of motor.
In preferred embodiment, electronic-controlled installation can comprise a microprocessor, above-mentioned differentiate unit 26, storage and processing unit 32, electronic control circuit 30 or be used for the delay cell (not shown) of delayed control signal s and can carry out by the instruction that is solidificated in the microprocessor.That is to say that electronic-controlled installation 22 can be replaced by a microprocessor.
Shown in Fig. 9-11 is the 3rd utility model principle of control method of the present utility model and electric tool, and it is based on and extends out on the first utility model principle shown in Fig. 1-4, therefore, both difference parts only is described below.The 3rd utility model principle has used electric current the differentiate for the third time of time to be reduced the rotating speed of electric tool 2.
In the specific embodiment, control method can continue each step shown in Fig. 1-3.Fig. 9 is the reproduction of electric current to the secondary differentiate curve of time, and this curve had shown in Fig. 3.As shown in figure 10, at second dervative d
2I/dt
2The basis on, further obtained the three order derivative ds of electric current to the time
3I/dt
3After the crest section of three order derivative curves occurs, if detect three order derivative value d
3I/dt
3Greater than the threshold values v1 that provides in advance, and be on the occasion of the time, control signal s just has been generated.Control signal s is used to reduce the rotating speed of electric tool 2 subsequently.
Those skilled in the art can learn according to inferior, by detect quadravalence, five rank or more the derivative of high-order realize the generation of control signal s.Because these can infer easily that all the applicant is not giving unnecessary details at this.
With reference to circuit shown in Figure 11, it should be noted that the signal of secondary differentiate unit 28 outputs has passed to differentiate unit 34 three times, generate three order derivative d then
3I/dt
3Along with the 3rd differentiate element output signal, a positive pulse value p1 has been transfused to electronic control circuit 30, and it is considered control signal s.By electronic control circuit 30, control signal s makes the DC current i that supplies with motor 6 be reduced or even be disconnected fully.
What need attention once more is that all component units of electronic-controlled installation 22 can be replaced by a microprocessor.
In second embodiment of mentioning before, storage can store first derivative values q2 within it with processing unit 32, perhaps can comprise some first derivative values q1, q2, q3 ... qn and some threshold values P1, P2, P3 ... Pn handles.
The head that described step of Fig. 5-8 and protective device have equally at screw 14 arrives the quick and response reliably of plank 16 surface back generation.This protective device is all realized by the electronics mode.
It should be noted that the first derivative mentioned in the respective embodiments described above, second dervative or more higher derivative be not limited in derivative definition on the pure mathematics meaning, can also comprise in the practical engineering application and carry out the simple equivalent conversion based on the derivative principle.For example, first derivative also can be expressed as the electric current changes delta i in the continuous time interval Δ t, i.e. Δ i/ Δ t.For making things convenient for engineering to use, Δ t can be taken as a very little equivalence, as Δ t=10ms, so, the difference that only needs constantly to judge current i just can realize being equivalent to the computing of asking first derivative.For example, detecting current value at continuous Fixed Time Interval point is i1, i2, i3, i4, i5......, so corresponding first derivative is i2-i1, i3-i2, i4-i3, i5-i4......, and second dervative is i3-2i2+i1, i4-2i3+i2, i5-2i4+i3.......And, in this way, can not need to try to achieve first derivative in advance and directly obtain second dervative.Analogize in view of the above, the similar equivalent transformation that higher derivative is more done is included in the implication of derivative in the utility model.
Below will discuss based on second dervative or more higher derivative generate another embodiment of control signal.With the second dervative is example, and electric screw driver can be met some abnormal conditions sometimes and cause operating current that improper sudden change takes place, thereby make the second dervative that is obtained disturbed when work.These abnormal conditions as, in screw is being screwed into the process of plank, run into the knot in the plank and cause electric current to raise suddenly; Perhaps electric current significantly rises suddenly and just detects when also not entering the stage of stable development when motor just starts; Perhaps when using the dc-battery bag as power supply, power brick causes voltage to descend rapidly because of crossing to put, and then makes electric current undergo mutation; Perhaps user's arm generation in use shake suddenly, and cause current break.If screw also was not screwed into plank fully when above-mentioned situation took place, the second dervative that time is calculated according at this moment electric current just might produce interference, that is to say, the second dervative that generate this moment may also can meet or exceed pre-set threshold value v (as shown in Figure 3), and this moment Control Component, electronic-controlled installation 22 as shown in Figure 4 will think mistakenly that screw has been screwed in the plank fully and the electric power of sever supply motor, and this obviously is not to use the person to be unwilling to see.
When running into above-mentioned abnormal conditions; current value when the current value of this moment is often compared screw and is screwed into plank fully is little; institute thinks and addresses the above problem; Control Component can carry out product with corresponding current value (i.e. the value of corresponding this second dervative that calculates based on this current value) with the value of second dervative; and be the default new threshold values of this product value, when the product of this second dervative and corresponding electric current on the occasion of and numerical value during more than or equal to new threshold values the generation control signal corresponding reduce the speed or the shutdown of motor.Obviously, new threshold values is more much bigger than former threshold values v, in this way, makes actual second dervative of wanting and the gap that produces between the second dervative of disturbing be exaggerated, thereby uses bigger threshold values that the actual second dervative of wanting is screened.Certainly in other embodiments; can be with the product of electric current or first derivative or a second dervative and a fixed constant; the n power of electric current or first derivative or second dervative; the product of electric current and corresponding first derivative; the product of second dervative and corresponding first derivative; the product of second dervative and corresponding first derivative and electric current; single order or second dervative add that certain levels off to and ask tan value (as tan (89+ single order or second dervative)) again after 90 the value; the cotangent functional value of single order or second dervative (as ctan (single order or second dervative)); or be the truth of a matter and numerical value 1 with the difference of single order or second dervative with arbitrary value a be that the logarithmic function value (as loga (1-single order or second dervative)) of antilog compares with corresponding threshold values; when above-mentioned value when numerical value (being absolute value) is gone up more than or equal to its corresponding threshold values (this threshold values is a positive number), generate speed or shutdown that control signal reduces motor.Those of ordinary skills can expect easily the time, above-mentioned embodiment can be applicable to higher derivative equally, the applicant is no longer given unnecessary details at this.
In the above-mentioned embodiment, all represent the load of output shaft (being the connecting axle between chuck 10 and clutch system 12 among Fig. 8 and Figure 11) as detected parameters with the electric current of motor, that is to say, be screwed into when screw in the process of plank, output shaft can be subjected to the moment of resistance, just can reflect the variation of the moment of resistance by detecting electric current, thereby judge whether screw is screwed in the plank fully.Certainly, what those skilled in the art can expect easily is, is used for representing that the parameter of output shaft load is not limited to electric current, can also be voltage, as detecting the ohmically pressure drop of connecting with motor; Or rotating speed, detect the rotating speed of motor or output shaft as adopting Hall effect detecting element (HallSensor); Or efficiency of motor, as recently detecting efficiency of motor by output and the input power of calculating motor.
Figure 12 has disclosed a kind of concrete detection mode to Figure 15.As shown in figure 12, in the present embodiment, still is example with electric screw driver 2, it comprises casing 5, be arranged on motor 6, output shaft 9 in the casing, be connected the gear reduction 7 between motor 6 and the output shaft 9 and be arranged on chuck 10 on the output shaft 9.In the present embodiment, gear reduction 7 is the third-level planetary gear reduction, it comprises first, second and third planet carrier 71,72,73, be arranged on some first, second and third planetary gears 711,721,731 on the corresponding planet carrier, and first, second and third gear ring 712,722,732 that is arranged on corresponding several rows star-wheel periphery.In the present embodiment, a torsion spring 51 is arranged between casing 5 and the 3rd gear ring 732, a wherein end of torsion spring 51 and casing 5 relative fixed settings, and the other end is fixedlyed connected with the 3rd gear ring 732.When output shaft 9 suffered loads changed, the 3rd gear ring 732 can overcome the torsion of torsion spring 51 and rotate.Sensor cluster 24 is arranged between casing 5 and the 3rd gear ring 732 equally.Shown in the structure for amplifying of Figure 13, sensor cluster 24 comprises the sensing member 241 that is fixedly installed on the casing 5 and is fixedly installed on moving member 242 on the 3rd gear ring 732, in the present embodiment, sensing member 241 is preferably photoelectric sensor, and moving member 242 is preferably the blanking disc of annular.Cooperation is referring to shown in Figure 14, blanking disc 242 comprises a plurality of through holes 2421 that evenly are arranged on the circumference, in addition, and referring to shown in Figure 15, blanking disc 242 also can use light transmissive material to make, and evenly is provided with a plurality of lighttight stripeds 2422 on the circumference of blanking disc 242.
When the 3rd gear ring 732 rotates, it can drive blanking disc 242 and rotate with respect to photoelectric sensor 241, thereby the light that photoelectric sensor 241 sends just can be covered by blanking disc 242, perhaps pass the through hole 2421 of blanking disc 242, photoelectric sensor 241 is noted the number of the through hole 2421 that passes through and production burst signal, and (angular displacement is represented in each pulse, be angular displacement/pulse), this signal passes to Control Component, Control Component is through calculating, pulse signal is converted into the corresponding angular amount, multiplying each other according to the rigidity (moment of torsion/angle) of torsion spring 51 and angular displacement simultaneously obtains the suffered moment of torsion of torsion spring 51, thereby draws the size of the suffered load torque of output shaft 9.In the present embodiment, obtain the load torque of output shaft by the displacement that detects the relative casing of gear ring, certainly in other embodiments, also can be by detecting the pressure (as passing through pressure sensor) that ring gear acts on casing, the size of output shaft load torque is represented or further calculated to the rotating speed (ear detecting element suddenly) that perhaps detects planet carrier.
Above-mentioned is that example describes with the electric screw driver, and certainly, control method of the present utility model also can be applied to other electric tools, as electric drill, electric wrench etc.Because this application for the ordinary skill in the art, can realize by above-mentioned embodiment, easily so the applicant is no longer given unnecessary details at this.
Claims (4)
1. an electric tool is characterized in that, this electric tool comprises:
Output shaft is used to drive a working head, so that working head has a rotary speed;
Motor, rotation drives described output shaft;
Power supply is used to supply with described motor electric power;
Sensor is used to measure the parameter of expression output shaft load;
Control Component is used for
Obtain second dervative or the higher derivative of described parameter to the time;
Generate control signal corresponding to change the rotary speed of described motor according to described second dervative or higher derivative.
2. electric tool according to claim 1 is characterized in that: described parameter is an electric current.
3. electric tool according to claim 1 is characterized in that: described parameter is in voltage, motor speed or the electric efficiency of output shaft rotating speed, motor.
4. electric tool according to claim 1, it is characterized in that: described electric tool also comprises casing and is housed in planetary gear mechanism in the casing, the gear ring that described planetary gear mechanism comprises planet carrier, be arranged on planetary gear on the planet carrier, be provided with around planetary gear; Described parameter is in the displacement of rotating speed, the relative casing of gear ring of planet carrier, the pressure that gear ring acts on casing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200920038393XU CN201405335Y (en) | 2009-01-16 | 2009-01-16 | Electric tool |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200920038393XU CN201405335Y (en) | 2009-01-16 | 2009-01-16 | Electric tool |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201405335Y true CN201405335Y (en) | 2010-02-17 |
Family
ID=41676259
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200920038393XU Expired - Lifetime CN201405335Y (en) | 2009-01-16 | 2009-01-16 | Electric tool |
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| CN (1) | CN201405335Y (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010075820A1 (en) * | 2009-01-04 | 2010-07-08 | 苏州宝时得电动工具有限公司 | Control method for power tool and power tool executing control method |
| US8881842B2 (en) | 2007-02-16 | 2014-11-11 | Positec Power Tools (Suzhou) Co., Ltd. | Controlling method of electric tool and electric tool carrying out the controlling method |
| CN104647264A (en) * | 2014-09-02 | 2015-05-27 | 苏州宝时得电动工具有限公司 | Electric tool and control method |
| CN105093973A (en) * | 2014-05-16 | 2015-11-25 | 苏州宝时得电动工具有限公司 | Electric tool and control method thereof |
| CN106346403A (en) * | 2015-07-14 | 2017-01-25 | 苏州宝时得电动工具有限公司 | Electric tool and electric tool control method |
| CN109995307A (en) * | 2017-12-29 | 2019-07-09 | 苏州宝时得电动工具有限公司 | The control method of electric tool and the electric tool for executing the control method |
-
2009
- 2009-01-16 CN CN200920038393XU patent/CN201405335Y/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8881842B2 (en) | 2007-02-16 | 2014-11-11 | Positec Power Tools (Suzhou) Co., Ltd. | Controlling method of electric tool and electric tool carrying out the controlling method |
| WO2010075820A1 (en) * | 2009-01-04 | 2010-07-08 | 苏州宝时得电动工具有限公司 | Control method for power tool and power tool executing control method |
| US9162331B2 (en) | 2009-01-04 | 2015-10-20 | Positec Power Tools (Suzhou) Co. Ltd. | Electric tool and controlling method thereof |
| CN105093973A (en) * | 2014-05-16 | 2015-11-25 | 苏州宝时得电动工具有限公司 | Electric tool and control method thereof |
| CN104647264A (en) * | 2014-09-02 | 2015-05-27 | 苏州宝时得电动工具有限公司 | Electric tool and control method |
| CN106346403A (en) * | 2015-07-14 | 2017-01-25 | 苏州宝时得电动工具有限公司 | Electric tool and electric tool control method |
| CN109995307A (en) * | 2017-12-29 | 2019-07-09 | 苏州宝时得电动工具有限公司 | The control method of electric tool and the electric tool for executing the control method |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
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Granted publication date: 20100217 |