CN104485860A - Control method for electric tool and electric tool performing control method - Google Patents
Control method for electric tool and electric tool performing control method Download PDFInfo
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Abstract
The invention relates to a control method for an electric tool. The electric tool comprises an output shaft. The control method comprises steps that a parameter which changes along with the time and is used for expressing an output shaft load is measured; a first order derivative of the parameter for the time is acquired; a second order derivative or a higher-order derivative of the parameter for the time is acquired; a corresponding control signal is generated according to the product of the first order derivative and the second order derivative or the product of the first order derivative and the higher-order derivative; output of the output shaft is changed according to the control signal. The invention further relates to the electric tool performing the control method. According to the electric tool and the control method thereof, whether a work piece driven by a work head arrives a predetermined position can be automatically detected, corresponding motion is performed when the work piece is detected to arrive the predetermined position, so the work piece is guaranteed not to cross the predetermined position.
Description
Technical field
The present invention relates to a kind of control method of electric tool, particularly relating to a kind of method of output of the output shaft for controlling electric screwdriver.
The invention still further relates to a kind of electric tool performing above-mentioned control method, particularly relate to a kind of electric screwdriver performing this control method.
Background technology
Existing electric tool, as electric screwdriver, provides electric current by the power supply loaded, and carrys out drive motors and rotates, thus working head is rotated to be crept in plank by screw.Dissimilar screw has different main diameters, or has different nose shapes, and so, its situation of creeping in same plank is also different.In addition, different planks makes its hardness also different due to material difference, and so, the situation that same screw creeps in the plank of unlike material is also not quite similar.Usually in the use procedure of electric screwdriver, user needs screw to be drilled into the surface that head presses close to workpiece, and so, user needs to pay close attention to drilling process very carefully, controls motor stalling during to press close to workpiece surperficial when the head of screw.Thus, avoid screw head to be pierced plank inside too far on the one hand, after avoiding screw head to be crept into plank because of carelessness on the other hand, make motor overload owing to suffering excessive resistance.
Usual this electric tool can be provided with overload protection arrangement.This overload protection arrangement can be a kind of mechanical clutch, when above-mentioned current overload, the working head of electric tool can be departed from motor and coordinate.Adopt the electric tool of this overload protection arrangement usually can be provided with a torque cover in the front portion of its casing, namely one indicates the rotatable cover of some scales simultaneously.These scales represent the limit torsion gear of electric tool work.The limit torque value of electric tool work can be set in advance by rotary torsion cover when user uses, that is, when the torsional moment exported in electric tool work meets or exceeds the threshold values that this presets, clutch system automatically can be started working and the working head of electric tool and motor be departed from coordinate.In addition, adopting the electric screwdriver of this overload protection arrangement also can be extend a sleeve pipe in the front end of its casing, remains basically stable in the front end of the front end of this sleeve pipe and the working head of electric screwdriver.Pass through this set, when its head that screw gets into is attached to plank surperficial, the leading section of sleeve pipe is also attached to the surface of plank, then bores dynamic screw further, sleeve pipe can be subject to compressing of plank and make it touch clutch mechanism in casing, thus working head and motor is departed from coordinate.But above-mentioned mechanical clutch structure is all comparatively complicated, make trouble, cost is higher.
Summary of the invention
The invention provides a kind of control method of electric tool, it can guarantee that the work package driven by the working head of electric tool arrives precalculated position automatically, and this work package can not cross this precalculated position further.
For achieving the above object, technical scheme provided by the invention is: a kind of control method of electric tool, wherein electric tool comprises motor and the output shaft by motor rotary actuation, described output shaft works to drive working head for exporting rotation torque on workpiece, and described control method comprises the steps: to measure the time dependent parameter being used for representing output shaft load; Obtain the first derivative of described parameters versus time; Obtain second dervative or the higher derivative of described parameters versus time; Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative; And the output of described output shaft is changed according to described control signal.
For achieving the above object, the technical scheme that the present invention also provides is: a kind of control method of electric tool, wherein electric tool comprises motor and the output shaft by motor rotary actuation, described output shaft works to drive working head for exporting rotation torque on workpiece, and described control method comprises the steps: to measure the time dependent parameter being used for representing output shaft load; Obtain the first derivative of described parameters versus time; Obtain second dervative or the higher derivative of described parameters versus time; Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative; And the output of described output shaft is adjusted according to described control signal.
The present invention also provides a kind of electric tool performing above-mentioned control method, and it has Electronic Control Unit, and the work package driven by working head can be avoided behind arrival precalculated position to cross this position further.
For achieving the above object, technical scheme provided by the invention is: a kind of electric tool, and described electric tool comprises: output shaft, for driving working head, has rotary speed to make working head; Motor, output shaft described in rotary actuation; Power supply, for supplying described motor electric power; Transducer, for measuring the parameter representing output shaft load; Control assembly, for obtaining the first derivative of described parameters versus time; Obtain second dervative or the higher derivative of described parameters versus time; Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative; The output of described output shaft is changed according to described control signal.
For achieving the above object, the technical scheme that the present invention also provides is: a kind of electric tool, and this electric tool comprises: output shaft, for driving working head, has rotary speed to make working head; Motor, output shaft described in rotary actuation; Power supply, for supplying described motor electric power; Transducer, for measuring the parameter representing output shaft load; Control assembly, for obtaining the first derivative of described parameters versus time; Obtain second dervative or the higher derivative of described parameters versus time; Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative; The output of described output shaft is adjusted according to described control signal.
Compared with prior art, whether the present invention carrys out the driving of automatic testing head work package by setting up relevant Electronic Control Unit in electric tool arrives precalculated position, and after this work package arrival precalculated position being detected, perform corresponding actions, guarantee that it can not cross this precalculated position further.Further, owing to not adopting complicated mechanical clutch structure, make manufacture simple, cost reduces.
Accompanying drawing explanation
Below in conjunction with drawings and embodiments, the invention will be further described.
Electric current when Fig. 1 is the work of existing electric screwdriver and the graph of relation of time.
Fig. 2 is the derivative curve figure in Fig. 1 after a Current versus time differentiate.
Fig. 3 is the derivative curve figure in Fig. 1 after the differentiate of Current versus time secondary.
Fig. 4 is the operation principle block diagram of electric tool of the present invention based on the first inventive principle.
Fig. 5 is the electric current of power screw when arriving work and the graph of relation of time, two different current i 1 when which show corresponding two kinds of different operative scenario, the curve of i2.
Fig. 6 is that different current i 1 in Fig. 5, i2 are to the derivative curve figure after a time differentiate.
Fig. 7 is the curve chart according to current i 1 different in Fig. 6, control signal s1 that i2 obtains the first derivative of time, s2.
Fig. 8 is the operation principle block diagram of electric tool of the present invention based on the second inventive principle.
Fig. 9 and Fig. 3 is similar, is that the operating current of electric screwdriver is to the derivative curve figure after time secondary differentiate.
Figure 10 is the derivative curve figure in Fig. 9 after Current versus time three differentiates.
Figure 11 is the operation principle block diagram of electric tool of the present invention based on the 3rd inventive principle.
Figure 12 is the cross-sectional schematic of another execution mode of electric tool of the present invention.
Figure 13 is partial enlarged drawing in Figure 12.
Figure 14 is the schematic perspective view of blanking disc in Figure 13.
Figure 15 is the schematic perspective view of another execution mode of blanking disc in Figure 13.
Embodiment
Control method of the present invention can be applicable to polytype electric tool, and main is below that embodiment is described with electric screwdriver.
Electric current curve chart over time when electric screwdriver as shown in Figure 1 works.Coordinate with reference to shown in Fig. 4, this electric screwdriver 2 is pressed to order about work package 14 by user, and this work package is screw in the present embodiment, pierces in a plank 16.The pressing force of user is substantially close to a constant.Wherein alphabetical t represents that screw pierces time and screw corresponding position in plank thereupon of plank.Letter i represents the electric current of the motor being supplied to electric screwdriver and is thereupon correspondingly carried in load on motor or actuating force.
Curve in Fig. 1 comprises Part I A, Part II K, and Part III B.Wherein Part I A is one section of ascending curve, and it represents that the main part of screw pierces the drilling process of plank, and this section of ascending curve is linear substantially, or can some bend and setback a little.The Part II K following hard on Part I A may also be referred to as inflection portions (knee) K.This inflection portions K is the curvilinear motion of a forward, and that is, inflection portions K has acclivitous sudden change relative to Part I A, and this represents that the head of screw starts the surface touching plank.That follow inflection portions K closely is Part III B, and it is one section is equally linear substantially, or some can bend the ascending curve with setback a little.But curve B is much more precipitous than curve A.
In fact; what the curve in Fig. 1 represented is do not apply the working condition that control method of the present invention carries out the electric tool protected, so the Part III B of curve represents that now electric tool can produce very high electric current and cause the head of screw to pierce in plank.Therefore, be necessary after inflection portions K, take necessary measure to occur to avoid the situation of above-mentioned generation excessive current.
When screw is drilled into the position corresponding with inflection portions K, continues the process that pierces and the head of screw not only can be made to pierce in plank, and may motor be damaged.So the present invention is based on automatically detecting inflection portions K, then automatically taking corresponding precautionary measures after detecting.
How Fig. 2 and Fig. 3 detects inflection portions K by explanation present embodiment.
Fig. 2 is that in Fig. 1, current i asks the curve chart after first derivative di/dt to time t.Wherein, the Part I A in Fig. 1 and Part II B is corresponding on this figure is shown as the straight line being parallel to horizontal axis t, and Part II K is then shown as a curve risen rapidly.
Fig. 2 is that in Fig. 1, current i asks second dervative d to time t
2i/dt
2after curve chart.Wherein, Part I A in Fig. 1 and Part II B is numerical value vanishing after secondary differentiate, Part II K is then shown as the parabola that Open Side Down, and forms a peak signal p in a parabolical top area given zone of parabola summit (comprise between).Coordinate with reference to shown in Fig. 4, when this peak signal p is formed, a control signal s can be produced thereupon.Certainly, in a preferred embodiment, a threshold values v can be preset, this control signal s only when peak signal p be on the occasion of and be numerically greater than default threshold values v time produce.Can easily it is contemplated that this control signal s also can produce after current i is to t time, differentiate first time for those of ordinary skill in the art, as the mode by capacitor, when detecting that namely first derivative produces control signal s after being greater than a predetermined threshold values.
Shown in Fig. 4 is the electric tool of the above-mentioned control method of application of the present invention, is still described for electric screwdriver below.Electric screwdriver 2 comprises work package 4, power supply 18 and switch 20.Wherein work package 4 comprises motor 6, for driving a working head 8 to rotate, to be crept in plank 16 by a screw 14.Be connected with clutch system 12 and a chuck 10 by a mechanical type spring successively between motor 6 to working head 14.Certainly in the present embodiment, clutch system also can save.In present embodiment, power supply 18 is DC power supply, or rechargeable battery, can supply motor 6 direct current when switch 20 closes.Certainly, those of ordinary skill in the art also can expect easily, and employing AC power substitutes the DC power supply in present embodiment.
Electronic-controlled installation 22 and the transducer 24 for detecting electric current is connected with between power supply 18 and motor 6.This electric screwdriver also comprises one first differentiate unit 26 and the second differentiate unit 28.In present embodiment, transducer 24 can detect the current i of supply motor in real time, generates the signal proportional with the electric current detected simultaneously and passes to the first differentiate unit 26; Then the first differentiate unit 26 tries to achieve first derivative di/dt as shown in Figure 2 according to electric current and time, generates a signal proportional with this first derivative simultaneously and also passes to the second differentiate unit 28 further; Subsequently, the second differentiate unit 28 tries to achieve second dervative as shown in Figure 3, and when pre-conditioned generation, as noted above when peak signal p be on the occasion of and be numerically greater than default threshold values v time, generate control signal s.In the present embodiment, this control signal s is used to the rotating speed of reduction motor or interrupts providing electric power to motor.That is, control signal s is used to the current i of supply motor be reduced to a lower level or reduce to zero, thus reduces the rotating speed of motor or make motor stalling.Certainly, this control signal s also can be used to the flow direction changing current i, thus motor 6 can be stopped rapidly.In the present embodiment, control signal s can be passed to electronic-controlled installation 22, then perform corresponding action by electronic-controlled installation 22, these actions can be instant after peak signal p produces generations, also can be produce after postponing a period of time, this delay can realize in electronic-controlled installation 22, also can be realized by the delay cell arranged separately.
Electronic control circuit in Fig. 4 can comprise a transistor switch, is used for disconnecting the electric current supplying motor.
In a preferred embodiment, electronic-controlled installation 22 can comprise a microprocessor, and the function that above-mentioned first differentiate unit 26, second differentiate unit 28 or the delay cell etc. that may exist realize all can be performed by the instruction be solidificated in microprocessor.That is, whole electronic-controlled installation 22 can be a microprocessor.
In other optional execution modes, the current i of supply motor 6 can record in continuous print time interval Δ t, and these continuous print time intervals, Δ t can be identical.The current i detected is digitized process subsequently, asks the first derivative di/dt of the Current versus time in two continuous print time intervals respectively, then compares this two first derivatives; If the result compared shows that both substantially not identical (being equivalent to the secondary differentiate in aforementioned embodiments), namely means that the head of screw has arrived the surface of plank 16, can generate above-mentioned control signal s with that.
Whether above-mentioned execution mode carrys out the driving of automatic testing head work package by setting up relevant Electronic Control Unit in electric tool arrives precalculated position, and after this work package arrival precalculated position being detected, perform corresponding actions, guarantee that it can not cross this precalculated position further.
Shown in Fig. 5-8 is the second inventive principle of control method of the present invention and electric tool, below can be elaborated each execution mode based on this inventive principle.
Shown in Fig. 5 is the change curve of the current i t in time of motor.In the present embodiment, the current i of this motor is an electric screwdriver supplies motor direct current when driving one working head works.Two current curve A1 and A2 detected are shown in figure.Identical with above, detects and the electric current of processing motor is undertaken by clock pulse principle, and this belongs to technology well-known to those skilled in the art, and applicant repeats no more.Shown in Fig. 6 is current curve A1 and A2 corresponding first derivative curve after a differentiate.The workpiece of the first curve A 1 and relatively softwood matter, as plank, or relatively little screw is relevant; And the workpiece of the second curve A 2 and relative hard softwood matter, or relatively large screw is relevant.No matter which kind of situation, all can carry out in control assembly 22 (Fig. 8 shows) the detection of curve A 1 and A2 and process, in the present embodiment, this control assembly can also comprise a microprocessor.
Based in the first execution mode of the second inventive principle, at the time point T1 that presets, current of electric i1 is collected.In the microprocessor, be previously stored with the threshold values of, be called the first threshold values P1.This first threshold values P1 may be, such as, at T1 time point, and P1=5A (ampere).If now i1<5A, mean that current electric screwdriver just plays screw on one piece of softer plank; If now i1>5A, mean that current electric screwdriver just plays screw on one piece of harder plank.Coordinate with reference to shown in Fig. 6, if i1<5A, microprocessor will be assigned one first and be preset first derivative values q1; If i1<5A, microprocessor will be assigned one second and be preset first derivative values q2.Above-mentioned first and second preset first derivative values q1, q2 is all pre-stored in microprocessor.First presets first derivative values q1 can be, such as, and q1=0.4A/s; Second presets first derivative values q2 is greater than the first default first derivative values q1, Ke Yishi, such as, and q2=1A/s.That is, if motor current value i1 is lower than the first threshold values P1 when time point T1, first presets 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, so the second default first derivative values q2 can be selected.
In figure 6, the electric current of homologous thread A1 and A2 corresponding first derivative curve after a differentiate is shown as a1 and a2 respectively.
It is to be appreciated that in Fig. 6 curve a1 and a2 the corresponding diagram of ascent stage rapidly 5 in the abrupt bend section of curve A 1 and A2, namely inflection portions K1 and K2 of curve A 1 and A2.Mentioned above, inflection portions K1 and K2 represents that the head of screw starts to touch the surface of plank.These inflection portions K1 and K2 is used to generate control signal s1 and s2 (as shown in Figure 7) respectively in the microprocessor.As shown in Figure 6, the ascent stage rapidly that first derivative values q1, q2 lay respectively at curve a1, a2 is preset.
As shown in Figure 7, time the first default first derivative values q1 is selected, when the first derivative values di/dt of current of electric reaches q1, the first control signal s1 being now positioned at time point t1 can be generated by microprocessor.If determined selection second curve A 2 according to the detection when time point T1, so when first derivative values di/dt reach second preset first derivative values q2 time, the second control signal s2 being positioned at time point t2 is just generated.
According to the first control signal s1 generated or the second control signal s2, the rotating speed of the direct current machine of electric tool will reduce or even stall.
That is: when Preset Time point T1, such as, after starter motor 1 second or 2 seconds time, microcomputer reads current of electric i.If working head is Screw and/or workpiece is plank compared with softwood matter, operating current i is now relatively little, and the time dependent curve of electric current is just as the first curve A 1 in Fig. 5.The electric current collected when time point T1 is the first current i 1, can be about 3A, and microprocessor will select the first first derivative values q1 (being stored in advance wherein) to come to compare with the first derivative di/dt of Current versus time.So, when the value of di/dt reaches q1, corresponding time point is t1, and the electric current of corresponding supply motor is l1, now, the rotating speed of motor will the first control signal s1 of triggering by q1 control and reduction of speed.If working head is large screw and/or workpiece is the plank of harder material, now the time dependent curve of electric current is just as the second curve A 2 in Fig. 5.The second current i 2 so collected when time point T1 is understood higher than the first current i 1, such as, and i2=7A.Therefore, when Preset Time point T1, microprocessor will select the second first derivative values q2 (being stored in advance wherein).When the di/dt value on a2 curve reaches q2, corresponding time point is t2, and the electric current of corresponding supply motor is l2, and now, the second control signal s2 that the rotating speed of motor will be generated controls and reduction of speed.
Based in the second execution mode of the second inventive principle, the current of electric i when Preset Time point T1 equally can be collected.Now, microprocessor can judge whether the value of the current i detected when T1 can lower than the first threshold values P1 preset, such as, current value i1 in above-mentioned execution mode, or whether higher than the first threshold values P1 preset, but such as, lower than the second threshold values P2 preset, the current value i2 in above-mentioned execution mode.If the current value detected is i1, then the first curve A 1 will be dispatched to a default first derivative values q1; If the current value detected is i2, then the second curve A 2 will be dispatched to a larger default first derivative values q2.Next, just as the individual step mentioned in the first execution mode, be positioned at flex point K1, the first derivative di/dt of K2 again will use by microprocessor and generate corresponding control signal s1, s2.
It should be noted that and only have a pre-set threshold value P1 to be used in the first embodiment, and have two pre-set threshold value P1, P2 to be used in this second embodiment.
This equally also can be applied in the second execution mode: if to be the material of very large screw and/or workpiece stone for working head, 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 preset within it equally.It should be noted that, these threshold values P1, P2, P3 and these first derivative values q1, q2, q3 are stored in microprocessor in advance, for when Preset Time point T1, are waken up individually respectively according to different current value i1, i2, i3 of detecting.Certainly, visual situation uses more threshold values P and first derivative values q.
These threshold values P and first derivative values q is obtained by a series of test (screw such as, testing different size carries out work on the workpiece of unlike material or specification) and is stored in advance in the microprocessor.
Electric tool 2 shown in Fig. 8, such as electric screwdriver, employs the above-mentioned execution mode based on the second inventive principle and carries out work.Wherein, most of element is identical with the execution mode shown in Fig. 4 or close, so, identical label is used to these elements.
The work package 4 of the electric screwdriver shown in the right side of Fig. 8 comprises direct current machine 6, is used for driving the working head 8 be clamped on hammer 10.Be connected with clutch system 12 by a mechanical type spring between hammer 10 and motor 6.Working head 8 is for rotating a screw 14 to be screwed in plank 16.Power supply 18 is DC power supply, can be rechargeable battery, can supply motor 6 direct current i when trigger 20 closes.
Electronic-controlled installation 22 and the transducer 24 for detecting electric current is connected with between power supply 18 and motor 6.Current sensor 24 can detect the electric current of supply motor in real time, generates the signal proportional with the electric current detected simultaneously and passes to differentiate unit 26.Differentiate unit 26 generates a signal proportional with the first derivative di/dt of Current versus time subsequently.The output of differentiate unit 26 is connected to one and stores the input with processing unit 32.
Store and store in processing unit 32, as described in above-mentioned first execution mode, single threshold values P1 and the first and second first derivative values q1 and q2.At Preset Time point T1, if current i 1 is lower than threshold values P1, stores and select the first first derivative values q1 with processing unit 32; If current i 2 is higher than threshold values P1, then stores and select 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, store generation control signal s1 or s2 corresponding to processing unit 32.Now, screw head has arrived the surface of plank.Store, with processing unit 32, control signal s1 or s2 is passed to electronic-controlled installation 22.This electronic-controlled installation 22 is for reducing or disconnect the electric power of supply motor 6.That is, control signal s1 or s2 is used to make the current i of supply motor to be reduced to zero or lower value to be substantially zero to make motor stalling or rotating speed.In the present embodiment, control signal s is achieved this end by electronic control circuit 30.Controlling immediately after pulse signal p produces to perform to the reduction of speed of motor, also can be delay the specific time to perform.Control signal s1 or s2 also can be used for changing the flow direction of current i, thus makes the rapid stall of motor.
In a preferred embodiment, electronic-controlled installation can comprise a microprocessor, above-mentioned differentiate unit 26, stores and processing unit 32, electronic control circuit 30 or be used for the delay cell (not shown) of delayed control signal s and can be performed by the instruction be solidificated in microprocessor.That is, electronic-controlled installation 22 can be replaced by a microprocessor.
Shown in Fig. 9-11 is the 3rd inventive principle of control method of the present invention and electric tool, and it extends out based in the first inventive principle shown in Fig. 1-4, therefore, and the difference part both only illustrating below.3rd inventive principle employs the third time differentiate of Current versus time to reduce the rotating speed of electric tool 2.
In a specific embodiment, control method can continue each step shown in Fig. 1-3.Fig. 9 is the reproduction of the secondary differentiate curve of Current versus time, and this curve showed in figure 3.As shown in Figure 10, at second dervative d
2i/dt
2basis on, obtained three order derivative d of Current versus time further
3i/dt
3.After the crest section of three order derivative curves occurs, if three order derivative value d detected
3i/dt
3be greater than the threshold values v1 provided in advance, and be on the occasion of time, control signal s has just been generated.Control signal s is used to the rotating speed reducing electric tool 2 subsequently.
Those skilled in the art can learn according to secondary, and by detecting quadravalence, the derivative of five rank or more high-order realizes the generation of control signal s.Because these all can be inferred easily, applicant is not repeating at this.
With reference to the circuit shown in Figure 11, it should be noted that the signal transmission that secondary differentiate unit 28 exports gives three differentiate unit 34, then generate three order derivative d
3i/dt
3.Along 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 direct current i supplying motor 6 be reduced or be disconnected even completely.
Need again it is noted that all component units of electronic-controlled installation 22 can replace by the microprocessor.
According in the second execution mode mentioned before, store with processing unit 32 can store first derivative values q2 within it, or can comprise some first derivative values q1, q2, q3 ... qn and some threshold values P1, P2, P3 ... Pn processes.
Step described in Fig. 5-8 and protective device have the quick and reliable response of generation after the head arrival plank 16 of screw 14 is surperficial equally.This protective device is all realized by electronics mode.
It should be noted that mention in the respective embodiments described above first derivative, second dervative or more higher derivative be not limited in the Derivative Definition in pure mathematics meaning, can also comprise in practical engineering application and carry out simple equivalent transformation based on derivative principle.Such as, first derivative also can be expressed as the curent change Δ i in continuous print time interval Δ t, i.e. Δ i/ Δ t.For convenience of engineer applied, Δ t can be taken as a very little equivalence, as Δ t=10ms, so, only need constantly to judge that the difference of current i just can realize being equivalent to the computing asking first derivative.Such as, detect that current value is i1, i2, i3, i4, i5 at continuous print Fixed Time Interval point ... so corresponding first derivative is i2-i1, i3-i2, i4-i3, i5-i4 ..., second dervative is i3-2i2+i1, i4-2i3+i2, i5-2i4+i3 ...Further, in this way, can not need try to achieve first derivative in advance and directly obtain second dervative.Analogize accordingly, the similar equivalent transformation that more higher derivative is done is included in the implication of derivative in the present invention.
Below by discussion based on second dervative or more higher derivative generate another execution mode of control signal.For second dervative, electric screwdriver sometimes operationally can be met some abnormal conditions and cause operating current that improper sudden change occurs, thus makes obtained second dervative disturbed.These abnormal conditions as, in the process being screwed into plank, run into the knot in plank when screw and cause electric current to raise suddenly; Or electric current significantly rises suddenly and just detects when also not entering the stage of stable development when motor just starts; Or when using dc-battery bag as power supply, power brick causes voltage to decline rapidly because excessively putting, and then makes electric current undergo mutation; Or there is shake suddenly in user in use arm, and causes current break.If screw is not also screwed into plank completely when above-mentioned situation occurs, the second dervative calculated according to Current versus time at this moment just likely produces interference, that is, the second dervative now generated also may can meet or exceed pre-set threshold value v (as shown in Figure 3), and now control assembly, electronic-controlled installation 22 as shown in Figure 4, will think that screw has been screwed into the electric power of sever supply motor in plank completely mistakenly, and this is obviously that user is unwilling to see.
When running into above-mentioned abnormal conditions; the current value that current value now is often compared when screw is screwed into plank is completely little; institute thinks and solves the problem; the value of second dervative and corresponding current value (i.e. the value of corresponding this second dervative calculated based on this current value) can be carried out product by control assembly; and preset a new threshold values for this product value, when this second dervative and the product of phase induced current be on the occasion of and numerical value is more than or equal to new threshold values time generate corresponding control signal to reduce speed or the shutdown of motor.Obviously, new threshold values is more much bigger than former threshold values v, in this way, make the actual second dervative wanted and the gap produced between the second dervative disturb is exaggerated, thus the actual second dervative wanted is screened by the larger threshold values of use.Certainly in other embodiments, can by the product of electric current or first derivative or 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 certain level off to 90 value after ask tan value (as tan (89+ single order or second dervative)) again, the cotangent value (as ctan (single order or second dervative)) of single order or second dervative, or with arbitrary value a for the truth of a matter and the logarithmic function value (as loga (1-single order or second dervative)) that the difference of numerical value 1 and single order or second dervative is antilog compare with corresponding threshold values, when above-mentioned value is more than or equal to threshold values (this threshold values is a positive number) of its correspondence on numerical value (i.e. absolute value), generate speed or shutdown that control signal reduces motor.Those of ordinary skill in the art can expect easily time, above-mentioned execution mode can be applicable to higher derivative equally, and applicant is no longer repeated at this.
In above-mentioned execution mode, the load of output shaft (connecting axle namely in Fig. 8 and Figure 11 between chuck 10 and clutch system 12) is all represented using the electric current of motor as detected parameters, that is, when screw is in the process being screwed into plank, output shaft can be subject to the moment of resistance, just can reflect the change of the moment of resistance by detecting electric current, thus judge whether screw is screwed in plank completely.Certainly, those skilled in the art can, easily it is contemplated that be used for representing that the parameter of output shaft load is not limited to electric current, can also be voltage, as detected the ohmically pressure drop of connecting with motor; Or rotating speed, as the rotating speed adopting Hall effect detecting element (HallSensor) to detect motor or output shaft; Or the efficiency of motor, if the output by calculating motor and input power are than the efficiency detecting motor.
Figure 12 to Figure 15 discloses a kind of concrete detection mode.As shown in figure 12, in the present embodiment, or for electric screwdriver 2, it comprises casing 5, the motor 6 be arranged in casing, output shaft 9, the chuck 10 that is connected to the gear reduction 7 between motor 6 and output shaft 9 and is arranged on output shaft 9.In the present embodiment, gear reduction 7 is three-stage planetary gear reducing gear, it comprises first, second and third planet carrier 71,72,73, be arranged on first, second and third planetary gears 711,721,731 some in corresponding line carrier, and be arranged on first, second and third gear ring 712,722,732 of corresponding several rows star-wheel periphery.In present embodiment, a torsion spring 51 is arranged between casing 5 and the 3rd gear ring 732, and wherein one end of torsion spring 51 is relative with casing 5 is fixedly installed, and the other end is fixedly connected with the 3rd gear ring 732.When the load suffered by output shaft 9 changes, 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.As shown in the structure for amplifying of Figure 13, sensor cluster 24 comprises the sensing member 241 be fixedly installed on casing 5, and is fixedly installed on the moving member 242 on the 3rd gear ring 732, in present embodiment, sensing member 241 is preferably photoelectric sensor, and moving member 242 is preferably the blanking disc of annular.Coordinate shown in Figure 14, blanking disc 242 comprises the multiple through holes 2421 be evenly arranged on circumferentially, in addition, shown in Figure 15, blanking disc 242 also can use light transmissive material to make, blanking disc 242 be circumferentially evenly provided with multiple lighttight striped 2422.
Rotate when the 3rd gear ring 732 produces, it can drive blanking disc 242 to rotate relative to photoelectric sensor 241, thus the light that photoelectric sensor 241 sends just can be blocked dish 242 covers, or through the through hole 2421 of blanking disc 242, photoelectric sensor 241 record the number of the through hole 2421 passed through and production burst signal (each pulse represents angular displacement, i.e. angular displacement/pulse), this signal transmission is to control assembly, control assembly is through calculating, pulse signal is converted into corresponding angular displacement, to be multiplied with angular displacement the moment of torsion obtained suffered by torsion spring 51 according to the rigidity (moment of torsion/angle) of torsion spring 51 simultaneously, thus draw the size of the load torque suffered by output shaft 9.In the present embodiment, the load torque of output shaft is obtained by the displacement detecting the relative casing of gear ring, certainly in other embodiments, also can act on the pressure (as passed through pressure sensor) of casing by detecting ring gear, or the rotating speed of detect lines carrier (suddenly ear detecting element) represents or calculates further the size of output shaft load torque.
Above-mentionedly be described for electric screwdriver, certainly, control method of the present invention also can be applied to other electric tools, as electric drill, electric wrench etc.Due to this application for the ordinary skill in the art, realize easily by above-mentioned execution mode, so applicant is no longer repeated at this.
Claims (10)
1. a control method for electric tool, wherein electric tool comprises motor and the output shaft by motor rotary actuation, and described output shaft works to drive working head for exporting rotation torque on workpiece, and it is characterized in that, described control method comprises the steps:
Measure the time dependent parameter being used for representing output shaft load;
Obtain the first derivative of described parameters versus time;
Obtain second dervative or the higher derivative of described parameters versus time;
Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative; And
The output of described output shaft is changed according to described control signal.
2. a control method for electric tool, wherein electric tool comprises motor and the output shaft by motor rotary actuation, and described output shaft works to drive working head for exporting rotation torque on workpiece, and it is characterized in that, described control method comprises the steps:
Measure the time dependent parameter being used for representing output shaft load;
Obtain the first derivative of described parameters versus time;
Obtain second dervative or the higher derivative of described parameters versus time;
Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative; And
The output of described output shaft is adjusted according to described control signal.
3. control method according to claim 1 and 2, is characterized in that: described parameter is the electric current of supply electric tool.
4. control method according to claim 1 and 2, is characterized in that: described parameter is one in output shaft rotating speed, the voltage of motor, motor speed or electric efficiency.
5. control method according to claim 1 and 2, it is characterized in that: described electric tool also comprises casing and is housed in planetary gear mechanism in casing, described planetary gear mechanism comprise planet carrier, the planetary gear be arranged on planet carrier, the gear ring that arranges around planetary gear; One that described parameter is the rotating speed of planet carrier, the displacement of the relative casing of gear ring, gear ring act in the pressure of casing.
6. control method according to claim 1 and 2, it is characterized in that: also comprise before the step generating corresponding control signal and preset pre-set threshold value, generate corresponding control signal when first derivative is more than or equal to described pre-set threshold value to the product of second dervative or the product of described first derivative and higher derivative.
7. control method according to claim 1 and 2, is characterized in that: described control signal is instant or generate after predetermined time of delay.
8. an electric tool, is characterized in that, described electric tool comprises:
Output shaft, for driving working head, has rotary speed to make working head;
Motor, output shaft described in rotary actuation;
Power supply, for supplying described motor electric power;
Transducer, for measuring the parameter representing output shaft load;
Control assembly, for
Obtain the first derivative of described parameters versus time;
Obtain second dervative or the higher derivative of described parameters versus time;
Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative;
The output of described output shaft is changed according to described control signal.
9. an electric tool, is characterized in that, this electric tool comprises:
Output shaft, for driving working head, has rotary speed to make working head;
Motor, output shaft described in rotary actuation;
Power supply, for supplying described motor electric power;
Transducer, for measuring the parameter representing output shaft load;
Control assembly, for
Obtain the first derivative of described parameters versus time;
Obtain second dervative or the higher derivative of described parameters versus time;
Corresponding control signal is generated to the product of second dervative or the product of described first derivative and higher derivative according to described first derivative;
The output of described output shaft is adjusted according to described control signal.
10. electric tool according to claim 8 or claim 9, it is characterized in that: described control assembly stores pre-set threshold value, when first derivative and the product of second dervative or the product of described first derivative and higher derivative are more than or equal to described pre-set threshold value, described control assembly generates corresponding control signal.
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| CN201410624039.0A CN104485860B (en) | 2009-01-04 | 2009-01-04 | The control method of electric tool and the electric tool for performing the control method |
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| CN201410624039.0A CN104485860B (en) | 2009-01-04 | 2009-01-04 | The control method of electric tool and the electric tool for performing the control method |
| CN200910001862.5A CN101771379B (en) | 2009-01-04 | 2009-01-04 | Control method of electric tool and electric tool executing same |
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| CN200910001862.5A Division CN101771379B (en) | 2009-01-04 | 2009-01-04 | Control method of electric tool and electric tool executing same |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105818088A (en) * | 2016-03-14 | 2016-08-03 | 郑州时享电子技术有限公司 | Detection method and device for number of impact times of impact type fastening tool |
| CN106483846A (en) * | 2015-09-01 | 2017-03-08 | 苏州宝时得电动工具有限公司 | The control method of electric tool and the electric tool executing this 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 |
| TWI677408B (en) * | 2017-12-08 | 2019-11-21 | 日商肯耐克科技股份有限公司 | Tool, operation management device, operation management method and operation management system |
| CN114871983A (en) * | 2022-05-18 | 2022-08-09 | 深圳市冠腾达科技有限公司 | Electric screwdriver control method and system, computer storage medium and program product |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS57121477A (en) * | 1981-01-16 | 1982-07-28 | Matsushita Electric Ind Co Ltd | Fixed torque screw clamping device |
| CN100475449C (en) * | 2005-11-08 | 2009-04-08 | 车王电子股份有限公司 | Electric tool |
| CN101247100B (en) * | 2007-02-16 | 2012-01-25 | 苏州宝时得电动工具有限公司 | Electric tool control method and electric tool using the same |
| CN201093036Y (en) * | 2007-08-31 | 2008-07-30 | 苏州宝时得电动工具有限公司 | Speed changing tool |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106483846A (en) * | 2015-09-01 | 2017-03-08 | 苏州宝时得电动工具有限公司 | The control method of electric tool and the electric tool executing this control method |
| CN106483846B (en) * | 2015-09-01 | 2019-12-13 | 苏州宝时得电动工具有限公司 | Control method of electric tool and electric tool for executing control method |
| CN105818088A (en) * | 2016-03-14 | 2016-08-03 | 郑州时享电子技术有限公司 | Detection method and device for number of impact times of impact type fastening tool |
| TWI677408B (en) * | 2017-12-08 | 2019-11-21 | 日商肯耐克科技股份有限公司 | Tool, operation management device, operation management method and operation management system |
| 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 |
| CN114871983A (en) * | 2022-05-18 | 2022-08-09 | 深圳市冠腾达科技有限公司 | Electric screwdriver control method and system, computer storage medium and program product |
| CN114871983B (en) * | 2022-05-18 | 2023-11-24 | 深圳市冠腾达科技有限公司 | Electric screw driver control method and system, computer storage medium and program product |
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