CN101761615A - Speed change tool - Google Patents

Abstract

The invention discloses a speed change tool which comprises a motor, an output shaft, a gear transmission mechanism connected with the motor and the output shaft and a control system, wherein the control system comprises a control unit and a driving device, and the driving device is provided with a moving piece capable of moving between a first position and a second position in the gear transmission mechanism. When the moving piece is positioned at the first position and the second position, the output shaft has different output characteristics; and when a load torque is changed to a preset value, the control unit firstly adjusts the torque transmitted by the motor to the gear transmission mechanism and then controls the driving device to realize automatic gear shifting. The speed change tool can solve the problem of tooth beating generated in the process of the automatic gear shifting, thereby improving the electrical property of the tool and prolonging the service life of the tool.

Description

Speed change tool

Technical field

The present invention relates to a kind of speed change tool, especially a kind of instrument of the exportable different rotating speeds of band variable transmission mechanism by motor driven is as electric drill, screwdriver set and hammer drill etc.

Background technique

A kind of speed change tool as electric drill, screwdriver set and hammer drill etc., has the exportable different rotating speed of variable transmission mechanism to adapt to different load torques.The variable transmission mechanism of speed change tool all comprises the gear drive and the control system of connection motor and output shaft usually, thereby this control system makes output shaft export different speed by the meshing relation change velocity ratio of change with gear drive.In the prior art, make referrals in No. 6431289, the U. S. Patent, two ring gears in the planetary gears can be provided with respectively vertically movably forward and backward, switch the position of each ring gear with functional unit from outside, whereby, by together, can select the rotational speed of three kinds of output shafts with the rotation of planetary pinion and planet carrier one and independent rotation combination.But this manually operated alternative makes the operator have to pay close attention to working state, the load variations situation of instrument constantly and judges that what constantly should regulation and control system.This manual operation is to operator and unfriendly.And when operator's control operation component axial moves ring gear and then realizes planet carrier and the whirl-stop device clamping of shell the time, be easy to cause the tooth of beating between ring gear and the shell whirl-stop device, so not only cause gear shift to lose efficacy easily, and can cause the lost of life of gear, influence the working life of entire tool.

And for example U. S. Patent is announced the automatic transmission of No. 6824491 announcement, its control system can change according to load torque adjusts the output that realizes friction speed with the meshing relation of gear drive automatically, this control system is utilized the throw-out collar rotation of strap cam face to promote slip ring and is moved axially, and then the ring gear in the actuation gear driving mechanism moves axially and be arranged on the whirl-stop device clamping on the shell.European patent application discloses EP0787931A1 and also discloses a kind of automatic transmission.Above-mentioned these automatic transmissions are all realized automaitc shfit with the variation of the corresponding outputting torsion of position relationship change between the mechanical structure, this mechanical type gear makes that not only the mechanical realization of gear drive inside is more complicated, and owing to ring gear also rotated in the axially movable while, and shell is relatively-stationary, so when this gear the time in speed change, therefore the collision and be difficult to engagement mutually of the tooth of the ring gear in the rotation and the tooth of the whirl-stop device on the shell can't really realize automaitc shfit and carry out the purpose of industrialized implementation.

Summary of the invention

Technical problem to be solved by this invention is: a kind of speed change tool is provided, and this instrument comes simplified structure by the means of dynamo-electric combination, and is implemented in the purpose of doing automatic switchover between the different output gears.

Technological scheme of the present invention is:

A kind of speed change tool is characterized in that: this instrument comprises

Casing;

Motor is arranged in the casing, and outputting rotary power;

Output shaft;

Gear drive is arranged between motor and the output shaft, and is delivered on the output shaft with one in the plurality of gears reduction speed ratio that comprises first gear reduction ratio and the second gear reduction ratio at least rotation output with motor, and described gear drive comprises

At least one group of train of gearings, and

Moving part cooperates changeably with described train of gearings, and described moving part can and the corresponding primary importance of first gear reduction ratio and and the corresponding second place of second gear reduction ratio between move;

Control system, it comprises drive unit, is used to drive described moving part and moves to the second place from primary importance, also is used to drive described moving part and moves to primary importance from the second place.

Compared with prior art, the invention has the beneficial effects as follows: the present invention by drive unit is applied electric current, drives the ring gear linear motion by electronic control unit, thereby changes the reduction speed ratio of gear drive, and then realizes the purpose of automaitc shfit.

Description of drawings

Be that the present invention will be further described in conjunction with the accompanying drawings for example with the gear in the electric drill below.

Fig. 1 is the partial sectional view of speed change tool of the present invention.

Fig. 2 is the local enlarged diagram of the drive unit among Fig. 1.

Fig. 3 a is the gear drive sectional view of speed change tool of the present invention when being in high gear.

Fig. 3 b is the gear drive sectional view of speed change tool of the present invention when being in low gear.

Fig. 4 a is another embodiment's of drive unit of a speed change tool of the present invention partial sectional view.

Fig. 4 b is the local enlarged diagram of the drive unit among Fig. 4.

Fig. 5 is the control system functional-block diagram of speed change tool of the present invention.

Fig. 6 is the functional-block diagram of control unit first embodiment in the speed change tool control system of the present invention.

Fig. 7 is the functional-block diagram of control unit second embodiment in the speed change tool control system of the present invention.

Fig. 8 is the functional-block diagram of control unit the 3rd embodiment in the speed change tool control system of the present invention.

Fig. 9 efficiency curve diagram that to be speed change tool of the present invention at high speed operation and low cruise be is with the speed switching time of explanation speed change tool.

Figure 10 is another embodiment's of a speed change tool of the present invention side view, and wherein the part casing is removed to disclose the structure of drive unit, and at this moment, drive unit is in high speed position.

Figure 11 is similar to FIG. 10, and at this moment, drive unit is in high speed position.

Figure 12 is the cross-sectional schematic along A-A line direction among Figure 11.

Figure 13 is the cross-sectional schematic along B-B line direction among Figure 11.

Figure 14 is the cross-sectional schematic of the electromagnet apparatus of speed change tool shown in Fig. 9 and Figure 10.

Figure 15 is another embodiment's of a speed change tool of the present invention side view, has wherein shown signal occurrence device.

Figure 16 is the plan view of Figure 15 speed change tool, the velocity mode switch that wherein also further demonstrates side handle and can select high speed, low speed and automatic three kinds of patterns.

Figure 17 a is the cross-sectional schematic along C-C line direction among Figure 15, has wherein disclosed a kind of form of trigger switch.

Figure 17 b and Figure 17 a are similar, have wherein disclosed the form of another kind of trigger switch.

Figure 18 and Figure 16 are similar, but wherein the velocity mode switch only has at a high speed and two kinds of gears of low speed.

Figure 19 and Figure 18 are similar, but it does not have the velocity mode switch, only have to be used to show at a high speed and the LED lamp of lower-speed state.

Figure 20 is the reduced graph of the internal circuit of speed change tool shown in Figure 16.

Figure 21 is that processor is carried out the workflow diagram that auto-speed switches among Figure 20.

Figure 22 is that processor is carried out the workflow diagram that manual instantaneous velocity switches among Figure 20.

Figure 23 a and Figure 23 b are the floor map in another mode of execution of speed change tool of the present invention, and wherein speed change tool is in fast state and lower-speed state respectively.

Figure 24 is the cross-sectional schematic along D-D line direction among Figure 23 a.

Figure 25 is the part schematic perspective view of speed change tool of the present invention, has wherein disclosed another mode of execution of drive unit.

Figure 26 is the three-dimensional exploded view of drive unit among Figure 25.

Embodiment

Shown in Fig. 3 b, be drive unit first embodiment's of speed change tool control system of the present invention structural representation.A kind of speed change tool 9 comprises motor 2, motor power supply 1, starts/stop main switch 13, output shaft 6 and the gear drive 4 of motor.Gear drive 4 comprises first planetary gear set be made up of first planet wheel 40 and first planet carrier, by second planetary gear set that second planet wheel 42 and second planet carrier 43 are formed, be fixedly set on the tool housing whirl-stop device 44 and can axially movable moving part 45.Drive unit 5 is arranged on the gear drive 4, comprise actuator 52 and driving component 51, the actuator of present embodiment is to adopt an electromagnet apparatus, comprise two permanent magnets that keep at a certain distance away 521, be arranged at permanent magnet middle iron core 523 and coil 522, wherein iron core 523 is provided with a groove 524.Driving component is that an arc push rod 512 reaches the steel wire cover 513 that connects with this arc push rod 512.Described push rod 512 has the mating part that is arranged in the groove 524.Described moving part 45 is one to have the speed ring 45 of internal tooth 451 and end tooth 452, and the circular groove 453 that holds steel wire cover 513 is set on it.

When electromagnet is switched on, iron-core coil 523 will produce magnetic and attract with one of them of two permanent magnets 521.When if current of electromagnet is oppositely connected, 523 of iron cores can produce with another permanent magnet 521 and attract, and move together thereby drive push rod 512, steel wire cover 513 and speed ring 45.Top gear state shown in Fig. 3 a, this moment, iron core 523 was attracted by one of them permanent magnet 521, and is corresponding, and the internal tooth 451 of speed ring 45 meshes with first planet carrier 41 and second planet wheel 42 simultaneously, and this moment, the output speed of gear drive 4 was higher; Bottom gear state shown in Fig. 3 b, this moment, iron core 523 was attracted by another permanent magnet 521, and corresponding, the internal tooth 451 of speed ring 45 and second is taken turns 42 engagements, whirl-stop device 44 engagements on its end tooth 452 and the tool housing simultaneously, this moment, the output speed of gear drive 4 was lower.

Shown in Fig. 4 a and Fig. 4 b, be drive unit second embodiment's of speed change tool control system of the present invention structural representation.The electromagnet apparatus that adopts among described in front drive unit first embodiment its objective is by control current of electromagnet direction to change polarity, drives speed ring 45 and moves between high low gear.And in the present embodiment, use a servomotor 525 instead and be used as actuator, be used as driving component 51 with a screw rod 515, tapped push rod 512 and steel wire cover 513, positive and negative transferring by servomotor 525 drives push rod 512 moving on screw rod 515, move together thereby drive speed ring 45, realize the engagement of high low gear.

, be the control system functional-block diagram of speed change tool of the present invention please with further reference to Fig. 5.Described control system 8 comprises a processing unit 3 and drive unit 5.Wherein processing unit 3 comprises processor 30 and relevant input/output circuitry.One signal generator 35 is connected with processor, and is provided with functional switch 36 between speed change tool main circuit power 1 and processor 30.Drive unit 5 is controlled by the control signal of processor 30 outputs, so that carry out the automaitc shfit action, simultaneously, drive unit can feed back to gear signal processor 30.In the speed change tool operating process, according to operator's the custom or the actual demand of application, the operator can select functional switch 36 closures, thereby the Automatic Shift Control function of start-up control system 8, in other words, this functional switch 36 provides the switching function between speed change tool 9 manual modes and the automatic mode.When if operation only needs wherein some shift functions, but break function switch 36 then carries out gear-change operation with manual mode to speed change tool.

When speed change tool 9 was in automatic mode, the processor 30 of control system 8 detected the variation of the physical parameter of speed change tool, compares with predefined value, judges whether need begin to carry out automaitc shfit.Those skilled in the art also external discharge circuit of available processors replace processor 30 to compare computing.Physical parameter described here can be an electric parameter, such as motor current, voltage, also can be other parameters, such as the stress of motor or output shaft rotating speed, mechanical parts, moment of torsion etc.In some use occasion, the operator perhaps wishes still can to decide in its sole discretion the time point of gear shift under automatic mode, also can manually import a control signal by signal generator 35, makes control system realize automaitc shfit immediately.

In the automaitc shfit process, control unit 3 sends control signal and gives drive unit 5, and the actuator 52 in the drive unit 5 drives driving components 51 and moves, and then the moving part in the gear drive 4 45 is moved to low gear from high gear.In this process, if motor 2 is still being given gear drive 4 transmitting torques, be that moving part 45 still has certain rotating speed, and need after moving and 44 engagements of static whirl-stop device (ginseng Fig. 3 b), will cause the problem that takes place between moving part 45 and the whirl-stop device 44 to beat tooth and can't mesh smoothly.The present invention has proposed three kinds of solutions for addressing this problem, and below describes respectively.

With reference to Fig. 6, be control unit first embodiment's functional-block diagram of speed change tool control system of the present invention.Wherein processing unit 3 comprises processor 30, VM 31, load detecting circuit 32, driving device controls circuit 33 and gear signal feeder loop 34.In the main circuit of speed change tool 9, an electric switch 10 (such as field effect transistor, controllable silicon or relay etc.) further is set between power supply and the motor, this electric switch 10 is by VM 31 control on off operating modes.

When speed change tool is started shooting, 10 hysteresis a period of time (as the 0.1s) conductings again of processor 30 control apparatus switches, are at first sent instruction and are given driving device controls circuit 33 in the period at this section, oppositely switch on for electromagnet, drive unit 5 is reset to the high gear state.Power supply 1 is powered to allow motor 2 startups and be in top gear and is normally moved then.This moment, output shaft 6 drove working heads (not shown) processing that begins to hole.Load detecting circuit 32 is with the load current of characteristic frequency collection motor, and 30 motor load value and predetermined current values that load detecting circuit 32 is collected of processor compare.If the situation of predetermined current value appears exceeding for a long time in the motor load electric current, illustrate that then the working head load is big, instrument need change to bottom gear high pulling torque output state.Processor 30 transmission instructions earlier this moment are to VM 31, and control apparatus switch 10 is cut off the electricity supply and made the motor stall, the motor current vanishing.This moment, the speed of speed ring also can be reduced to zero rotating speed.

Afterwards, processor sends instruction and gives driving device controls circuit 33, and the electromagnet of drive unit 5 is oppositely switched on, and iron core 523 drives speed ring 45 and is moved, thereby realizes the conversion of high gear to low gear.Because before gear shift, the rotating speed of speed ring 45 has been zero, is converted in the bottom gear process at its gear, and its end tooth 452 is state of rest with the internal tooth 441 of whirl-stop device 44, therefore can enter the engaging position very smoothly, and avoid beating the generation of tooth problem.

When the gear signal feeder loop 34 in the control unit 3 contacts with another permanent magnet 521 at the iron core 523 that detects electromagnet (those skilled in the art also can be designed to detect the engaging position relation between speed ring and the gear assembly), then represent speed ring 45 successfully to move to low gear, processor then sends instruction and gives VM 31, make electric switch 10 conductings, power supply 1 recovers to give motor 2 power supplies, and motor enters low-speed big output services state.

Need to prove, speed change tool is in the high speed normal course of operation, because of some special circumstances the heavy load value appearance in short-term of motor load electric current appears often, in order to prevent the situation of gear shift action false tripping, can solve by the program of setting processor, have only the motor current that collects when load detecting circuit to exceed the predefined value regular hour when (is 0.5s such as design time), just begin to carry out gear shift control.Certainly, also can directly functional switch 36 be cut off and directly select manual mode, the false tripping gear shift is moved when avoiding not wishing automaitc shfit.Default current value then decides according to the top gear maximal work current value of instrument, is predefined value with 30 amperes in the present embodiment.In addition,,, also can import a control signal, thereby begin to carry out the automaitc shfit action immediately by the signal generator on the processor 30 35 even if the motor load electric current does not also exceed predefined value if the operator wishes starting automaitc shfit sometime.Further, processor also can be designed to have learning functionality, that is, the motor load electric current when the record operator passes through the signal generator input control signal at every turn is as the reference of initialization system predefined value.

Above-mentioned before automaitc shfit control unit 3 control apparatus switches 10 allow just wherein a kind of mode of execution of motor 2 temporary stoppages.Under normal conditions, if when the rotating speed of motor 2 is reduced to very little degree, the problem that tooth can not appear beating in speed ring 45 and the engagement of whirl-stop device 44 equally in the gearshift procedure.With reference to shown in Figure 7, be control unit second embodiment of speed change tool control system of the present invention.In the main circuit of speed change tool 9, electric switch 10 usefulness field effect transistors 11 between power supply and the motor replace, when needs carry out automaitc shfit, VM 31 provides motor corresponding work voltage by control field effect transistor 11, to reach the purpose that reduces motor rotary speed, thereby the speed ring 45 and the speed of whirl-stop device 44 are mated mutually, prevent to beat the generation of tooth phenomenon.Here the speed of indication is mated mutually and is meant that the speed ring 45 and the relative velocity of whirl-stop device 44 reach a scope that can make the two enter the engaging position smoothly.

Equally, as shown in Figure 8, be control unit the 3rd embodiment of speed change tool control system of the present invention.One clutch 12 is set between motor 2 and gear drive 4, this clutch 12 of VM 31 controls reduces the moment of torsion that motor 2 is passed to gear drive 4, also can realize the purpose of velocity modulation, promptly speed ring 45 move to whirl-stop device 44 position engaged before, reduce the rotating speed of speed ring 45, with the problem that prevents that tooth is beaten in appearance in the engagement process.

The embodiment of comprehensive above-mentioned several velocity modulation, spirit of the present invention as can be seen mainly is: control unit 3 is when detecting motor 2 loads and exceed predefined value for a long time, carry out velocity modulation by 31 pairs of moving parts of VM 45 and gear assembly, when the relative velocity of the two mates mutually, enter next gear engagement again, in other words, control unit is adjusted the moment of torsion that motor passes to gear drive earlier, accessory drive is realized automaitc shfit again, thereby effectively avoids the tooth problem of beating in the automaitc shfit process.

What deserves to be mentioned is in addition, after the automaitc shfit release, power supply 1 recovers to give motor 2 power supplies, motor 2 is from the utmost point slow-speed of revolution or even the zero instantaneous low rotation speed large torque output state that enters of rotating speed state, can cause a very big starting torque to the operator, if it is not tight that the operator grips, even can cause instrument from operator's hand, to get loose and cause danger.Be head it off, can realize the soft start of motor 2 by control field effect transistor 11 (ginseng Fig. 7).Particularly, after automaitc shfit finishes, when recovering motor 2 power supplies, control unit 3 is (such as 0.6s) in the time period of a setting, control field effect transistor by modes such as fixed frequency modulated PWM or Fixed width frequency modulation, increase the load voltage of motor 2 gradually, slowly recover motor 2, thereby avoid the impact sensation brought to the operator of starting motor of moment after the gear shift to operating voltage.

The structure that is disclosed more than using, the shifting control method of speed change tool of the present invention is, provide a kind of speed change tool to comprise the gear drive 4 of power supply 1, motor 2, output shaft 6, connection motor and output shaft, and control system 8, wherein gear drive 4 comprises an at least one gear assembly and a moving part, and the described moving part engagement system different with gear assembly can provide output shaft different output gears; Control system 8 is made up of control unit 3 and drive unit 5, and this shifting control method comprises:

1) load torque detects step: described control system detects the speed change tool physical parameter, such as detecting motor 2 load currents, voltage or output shaft rotating speed, judges the working state of speed change tool;

2) automaitc shfit step: the moving part of control gear driving mechanism moves to another gear.

Further comprise a velocity modulation step between described load torque detection and the automaitc shfit step, when the load torque of described output shaft changes to predetermined value, described control unit is adjusted the moment of torsion that motor passes to gear drive, the rotating speed of moving part and gear assembly is mated mutually, and promptly speed ring 45 reaches a scope that can make the two enter the engaging position smoothly with the relative velocity of whirl-stop device 44.

In the described velocity modulation step, reduce the moment of torsion that motor passes to gear drive by the input voltage that reduces motor.

After the automaitc shfit step, comprise that further the moving part gear detects step, to confirm that moving part has moved to another gear.

After the velocity modulation step, also comprise a motor soft start step, control system progressively strengthens the input voltage of motor in default time range, make motor recover moment of torsion output.

Below in conjunction with Fig. 9 to describing the opportunity that the auto-speed of speed change tool of the present invention switches.Shown in Figure 9 is the change curve of the complete machine delivery efficiency η of speed change tool with output shaft load torque T.Wherein the delivery efficiency η of complete machine is the ratio of the output power of the output power of output shaft and motor, η _HCurve is the delivery efficiency curve of complete machine when running up, η _LCurve is the delivery efficiency curve of complete machine when low-speed running.As can be seen from Figure, when complete machine when running up, along with the increase of load, delivery efficiency begins rapid increase, reduces rapidly immediately after reaching the highest delivery efficiency point; When complete machine during at low-speed running, along with the increase of load, delivery efficiency begins slow increase, and promptly slowly reduces after reaching the highest delivery efficiency point.When the load torque value equals Tc, high speed efficiency curve η _HWith low speed efficiency curve η _LIn this intersection, its intersection point is η c.And before this, the delivery efficiency of complete machine when running up will be higher than the delivery efficiency when low-speed running; After this, then the continuation along with load increases, the delivery efficiency of complete machine when running up will be lower than the delivery efficiency when low-speed running, so, when the load torque value reaches Tc, the motion speed of complete machine is switched to low speed from high speed, can guarantee that speed change can keep higher delivery efficiency always.Speed change tool of the present invention wishes to carry out the switching of arriving low speed at a high speed then by determining that the load torque value reaches the time point of Tc.

As shown in Figure 9, in the present embodiment, control system can detect the variation by the electric current of motor, is used for characterizing the load button square of output shaft.I wherein _HBe the current curve of output shaft when running up.Originally, output shaft is operated in high rotating speed, and when the load torque value reached Tc, at this moment, the current value that detects motor was Ic, in the present embodiment, Ic=30A (ampere), then, the control system accessory drive is carried out the switching from high speed to low speed.Need to prove that because the characteristic of dissimilar motor has nothing in common with each other, as adopts different motors, then the curve of delivery efficiency also has difference, so corresponding Ic value also might difference.In addition, the current value of employing monitoring motor reflects the load of output shaft in the present embodiment, in other embodiments, and can be by detecting the load that other physical parameters reflect output shaft.As the rotating speed of the rotating speed of the rotating speed of the moment of torsion of output shaft, output shaft, motor, gear train assembly middle gear or moment of torsion etc., perhaps when adopting DC power supply, the modes such as voltage change that also can detect battery terminal characterize the load of output shaft.

Figure 10-shown in Figure 14 is the another kind of mode of execution of speed change tool of the present invention, and in the present embodiment, electromagnet apparatus adopts two-way freeze mode electromagnet.So-called two-way freeze mode electromagnet promptly also can remain on iron core top and two positions of terminal of stroke under cold situation.As shown in figure 14, electromagnet apparatus 53 comprise the lengthwise setting metal shell 531, be arranged on two coils 532 distributing along longitudinal direction in the metal shell, be arranged on two between the coil permanent magnet 533, be arranged on by in the coil region surrounded and can be along the linearly moving iron core 534 of longitudinal direction, and fixedly install and lengthwise extends the outer push rod 535 of metal shell 531 with respect to iron core.Wherein, push rod 535 fore-end that protrudes out metal shell 531 is provided with groove 536.Be that push rod 531 and iron core 534 also can be wholely set for what those of ordinary skills can expect easily.Shown in Figure 14 is that push rod 535 is in going-back position, and can remain on this position owing to the attraction of permanent magnet 533 under cold situation.Cooperation is with reference to Figure 10 and shown in Figure 12, and a gear frame 54 is arranged between steel wire cover 513 and the push rod 535, and it comprises semi-circular bracket 541 of extending around gear-box 47 and the pair of sidewalls 542 of extending and being provided with at interval from the carriage bottom downwards.Wherein the two ends of carriage 541 and steel wire cover 513 the radial projection two ends that go out speed reducer 47 housings are fixedly connected respectively, contain electromagnet apparatus 53 in the interval region of sidewall 542, side-wall shaft is to extending back and being entrenched in the groove 536 of push rod 535 and keeping relative fixed with push rod.As shown in figure 12, be provided with guide mechanism between gear frame 54 and the casing 21.Wherein pair of sidewalls 542 each side extending of gear frame 54 go out a guide posts 543, convex with a pair of floor 544 on every side inwall of casing 21, are formed with guide slot 545 therebetween and accommodate and guide each guide posts 543 with corresponding.

Push rod 535 in the electromagnet apparatus 53 shown in Figure 10 is in progressive position, and promptly push rod extends the longer distance of metal shell outward, and owing to the attraction of permanent magnet remains on this position.At this moment, the reduction speed ratio of gear drive is lower, it is higher that motor passes to the output shaft rotating speed after by gear-box, that is to say, ring gear 45 (or claims speed ring, be the moving part in the present embodiment) the external tooth of internal tooth and planet wheel 42 and the external tooth of contiguous planet carrier 41 mesh simultaneously and guarantee relative fixed (cooperation) with reference to shown in Fig. 3 a, thereby can rotate with planet carrier and planet wheel.Cooperation is with reference to Figure 14, and behind logical forward current in the coil 532 of electromagnet apparatus 53, the magnetic field that coil 532 produces produces different magnetic poles at the lengthwise two ends of metal shell 531, thereby driving iron core 534 and push rod 535 move to going-back position.As shown in figure 10, push rod 535 drives gear frame 54, steel wire cover 513 and ring gear 45 displacement distance d together, has arrived position as shown in figure 11.Cooperation is with reference to shown in Fig. 3 b, and in this process, ring gear 45 moves vertically and breaks away from engagement with planet carrier 41, but still keeps engagement with planet wheel 42.When push rod 53 moved to going-back position, ring gear 45 kept relative fixed with whirl-stop device 44 engagements with casing.At this moment, the reduction speed ratio of gear drive 4 has increased one-level, and is lower thereby motor passes to the rotating speed of output shaft after by gear-box.Behind logical back current in the coil 532, coil forms reverse magnetic field, and so, push rod 535 is got back to going-back position as shown in figure 10, thereby gear drive 4 is returned to the output state of high reduction speed ratio.

Shown in Figure 13 is a kind of mode of execution of functional switch 36.In the present embodiment, this functional switch can be referred to as the velocity mode switch.Cooperation is with reference to the velocity mode switch 36 among Figure 16, and this switch comprises the protruding toggle 361 that is exposed at outside the casing 21, and is arranged on the conducting terminal that is connected with other electrical assemblys in the casing.Toggle 361 can be along the circumferential direction three position slippages on casing 21, difference corresponding automatic mode (A), fast mode (H), low-speed mode (L).Conducting terminal comprises first, second, third signal terminal 362 corresponding respectively with these three kinds of patterns, and ground terminal 363.Be connected with the circuit of other electrical assemblys in the control system and workflow will arrive in subsequent detailed description about the velocity mode switch.

Shown in Figure 15 is a kind of mode of execution of signal occurrence device 35.In the present embodiment, this device comprises the speed diverter switch that is arranged in the casing 21, after this switch is pressed triggering, control system promptly changes the flow direction of the electric current of supplying with electromagnet apparatus and realizes automaitc shfit, i.e. driving by electromagnet realizes the switching of gear drive between high reduction speed ratio and low reduction speed ratio.As shown in figure 16, as preferred embodiment, this device 35 comprises two these speed diverter switches, be symmetricly set in the both sides of casing 21, press any one switch and can trigger the switching of speed, like this, can operate easily for the left hand and right hand user.Shown in Figure 17 a and Figure 17 b is the concrete form of switch.Switch among Figure 17 a is a push-button switch 351, and it electrically connects (follow-up will being further described) by the electronic component in lead 3512 and the control system.Casing is provided with flexible retaining piece 353, presses retaining piece, and button 3511 also is pressed, and the contact (not shown) in the switch is connected, thereby the speed switching function is triggered.Adopt spring-piece type switch 352 among Figure 17 b, same, press retaining piece 353, shell fragment 3521 is connected with contact 3523, and at this moment, an electrical signal will be generated and pass to control system, thus control system execution speed changeover program (follow-up will being described specifically).Return Figure 16, in the present embodiment, velocity mode switch 36 and signal occurrence device 35 can be used in combination.When the toggle of velocity mode switch 36 was positioned at gear A, when promptly being in automatic mode, the conductively-closed of speed switching function that is to say that the speed diverter switch of pressing can't trigger the speed switching function; And when the toggle of velocity mode switch is positioned at gear H or L, when promptly being in high speed or low-speed mode, the function conductively-closed that auto-speed switches, at this moment, the speed diverter switch of pressing just can trigger the speed switching function, thereby the corresponding low-speed mode that switches to of fast mode meeting, low-speed mode then can correspondingly switch to fast mode.

In the present embodiment, also be provided with a side handle 22 on the casing 21, the position of the switch button of these side handle 22 distance signal generating means 35 has a specific range h in the axial direction, and this hand apart from tolerable user's the sorrowful handle of gripping can the while operation button switch.For example, when the user wants switch speed when operating, it can be with the thumb push switch button of the hand that grips sorrowful handle, thereby obtains the speed that it is wanted.Certainly, for what those of ordinary skills can expect easily be, above-mentioned switch button also can near main handle 23 (shown in Figure 10) be provided with and and form specific range between main handle, thereby the operation that the user also can come execution speed simultaneously to switch with the hand that grips main handle.

What Figure 18 and Figure 19 disclosed is other two kinds of implementations that signal occurrence device 35 is used.Velocity mode switch 36 shown in Figure 180 does not comprise the automatic mode gear, and like this, as long as press the speed diverter switch, the speed switching function will be by instantaneous starting, promptly from present high speed or corresponding low speed or the high gear of switching to of low gear.The mode of execution that Figure 19 disclosed does not comprise the velocity mode switch, in this mode of execution, speed change tool operates under the automatic mode, and casing 21 is provided with the LED lamp of the present motion speed state of representational tool, be in high speed operation as present instrument, then " H " LED lamp 371 Chang Liang, otherwise, then " L " LED lamp 372 Chang Liang.In the present embodiment, instrument start operation back acquiescence is moved under automatic mode, in case signal occurrence device 35 is triggered, then control system 8 is interrupted automatic operating mode, simultaneously, the reduction speed ratio of control system 8 control electromagnet apparatus 53 change gear driving mechanisms 4 is promptly switched present speed running state, as switching to low speed by high speed.Be triggered as signal occurrence device 35, then present speed running state is switched once more again, as switching at a high speed from low speed again.So, in the present embodiment,, then entered manual speed switch mode by signal occurrence device control in case the automatic mode that speed is switched is interrupted.Certainly be that above-mentioned signal occurrence device and concrete speed switching mode can be applicable to have the above reduction speed ratio of two-stage to be switched, as the gear train assembly with high, medium and low three speed for what those of ordinary skills can expect easily.

Shown in Figure 20 is the circuit diagram of the simplification in speed change tool one embodiment of the present invention.In this mode of execution, speed change tool provides electric power by external dc power 1, and this external dc power is the cell bag of being made up of some batteries.As preferred embodiment, this cell bag can be the lithium ion battery bag.Need to prove that said lithium ion battery is that negative material is the general name of the rechargeable battery of elemental lithium here, according to the difference of positive electrode, it can constitute many systems, as " lithium manganese " battery, and " lithium iron " battery etc.In the present embodiment, the lithium ion battery bag comprises by being connected into the battery pack that voltage rating is 18V by five lithium ion batteries that save 3.6V (volt).Certainly, for what those of ordinary skills can expect easily be, more or less battery of can optionally connecting is formed battery pack, as the lithium ion batteries of the four joint 3.6V (volt) that connect to become voltage rating be the battery pack of 14.4V, or six lithium ion batteries that save 3.6V (volt) of connecting to become voltage rating be the battery pack of 21.6V.In the present embodiment, also be provided with the identification resistance 386 of representing this cell bag voltage in the cell bag 1, be used for being discerned, thereby determining that the corresponding battery bag is crossed puts protected-type by electric tool.

As shown in figure 20, can cooperate simultaneously with reference to shown in Figure 6, in the present embodiment, the speed variator system of speed change tool comprises processor 30, VM 31, motor load testing circuit 32, driving device controls circuit 33, gear signal feeder loop 34, signal occurrence device 35 and functional switch 36.

Processor 30 can adopt MCU, PLC or CPU etc.In the present embodiment, processor 30 is a microcomputer control system (MCU), what those skilled in the art can be easy to expect is, MCU has generally included central processing unit (CPU), ROM (read-only memory) (ROM), random access memory (RAM), digital/analog converter (A/D converter), timer (timer), input/output end port (I/Oport) P1-P28 etc., because the working principle of these unit or function module is all known well by those of ordinary skill in the art, so the claimant is no longer given unnecessary details at this.

As shown in figure 20, main switch 13 is connected between cell bag 1 and the main circuit, can be used for controlling the break-make of main circuit.Button 131 (showing as Figure 10) on main handle 23 is when the person of being operated depresses, main circuit is switched on, by DC electrical source modular converter (DC/DC) 381, the voltage of cell bag 1 is converted into a lower constant voltage, be 5V in the present embodiment, be used for for processor 30, and electronic circuit electric power is provided.In the present embodiment, the port P20 of processor is connected with DC electrical source modular converter 381, port P19 ground connection, port P1 is connected by resistance R 5 with DC electrical source modular converter 381, thereby after main switch 13 closures, electric current after 381 conversions of DC electrical source modular converter is by port P20 input processor, and processor receives a reset signal and carries out initialization action from port P1.Main switch 13 not only can be used for the break-make of control circuit, also further can be used to control the rotating speed of motor.In the present embodiment, main switch 13 comprises a potentiometer (potentiometer), its be used for measuring the distance that button moved under the effect of operator presses and produce one with the proportional electrical signal of this displacement distance, as voltage value signal, this electrical signal sends processor 30 to by port P2, and the digital/analog converter of preprocessor becomes digital signal with this electrical signal conversion and handle and generate control signal corresponding.In the present embodiment, this control signal is pulsewidth modulation (PWM, a Pulse WidthModulation) signal, is used to control the voltage that is applied on the motor 22, and its port P12 by processor 30 exports to VM 31.VM 31 is made up of resistance R 19, power switch driver.Wherein the power switch driver is made up of some triodes, it is used to regulate the dutycycle of MOSFET, that is to say, the power switch driver is according to the pwm signal that receives, improve or reduce the continuous output time of voltage signal in the single cycle, thereby control the running speed of motor 22 by power switch component 10 (being electric switch).Wherein power switch component 10 can semiconductor switch, is mos field effect transistor (MOSFET, metallic oxidesemiconductor field effecttransistor) in the present embodiment.

The port P3 of processor 30 can be connected the operating voltage of gathering cell bag with cell bag 1, so that the discharge scenario of monitoring cell bag, and when brownout, take appropriate measures and remind the electric power of user or sever supply motor.As shown in figure 20, port P18, the P17 of processor 30, P16, P15 are connected with light emitting diode D2, D3, D4, D5 by resistance R 22, R23, R29, R30.These light emitting diodes can be located on the casing, are used for representing the dump energy of cell bag 1, wherein D2, D3, D4 transmitting green light, and D5 launches ruddiness.When electric weight is sufficient, D2, D3, the equal Chang Liang of D4, D5 does not work; When electric weight is medium, D3, D4 Chang Liang, D2, D5 do not work; When electric weight is low, D4 Chang Liang, D3, D2, D5 all do not work; And when electric weight was not enough, D2, D3, D4 did not all work, and D5 Chang Liang; When the electric weight wretched insufficiency, D2, D3, D4 all do not work, and D5 flicker, at this moment, cause danger for avoiding cell bag to cross putting, and the port P12 of processor is blocked and can't provides electric power to motor.In the present embodiment, for the cell bag of voltage rating Vb=18V, when 12.5V＜Vb≤14.5V, expression cell bag electric weight deficiency, thus D2, D3, D4 all do not work, and D5 Chang Liang; When Vb≤12.5V, expression cell bag electric weight wretched insufficiency, thus D2, D3, D4 all do not work, and the D5 flicker, simultaneously, the port P12 of processor 30 is blocked.

Be the running state of monitoring motor 22, processor can detect the operating current by motor in real time.As shown in figure 20, one detects resistance 383 connects with switch 10 and motor 22, and an amplifier 382 is used for detecting the pressure drop signal amplification of generation on the resistance 383 and is input to processor 30 by port P4, so that the electric current that processor 30 detects by motor 22.In addition, also comprise over-current protection circuit 37 in the circuit, it comprises a comparator 384, and it passes through the pressure drop signal that resistance R 18 is gathered on the R6, and makes comparisons with the reference voltage signal Vref that imports.When the magnitude of voltage that collects during greater than reference voltage Vref, comparator 384 is converted to low level state with the high level state of initialization, and low level signal is exported to the port P21 of processor 30 by resistance R 24.In addition, for avoiding motor 22 operating temperatures too high, the resistance that can utilize thermistor 385 varies with temperature and the characteristic of linear change detects the temperature of motor.Thermistor 385 is composed in series bleeder circuit with resistance R 10, the port P5 of processor 30 by lead be connected 385 and resistance R 10 between, detect the voltage change on the thermistor 385, thereby be convenient to processor 30 real-time monitoring motor 22 variation of temperature, and surpass predetermined value at motor temperature, disconnect the electric power of supply motor.

Control system also comprises the recognition circuit that is used to discern cell bag 1 voltage.In the present embodiment, this recognition circuit is to be connected the back with speed change tool by identification resistance 386 in cell bag 1, and the bleeder circuit of resistance R 13 and R21 composition.Processor port P7 is connected between resistance R 13 and the identification resistance 386 by resistance R 21, is used for pressure drop on the sensing identification resistance 386, thereby determines the voltage of cell bag 1, and carries out the program that corresponding mistake is put protection.

In the present embodiment, driving device controls circuit 33 is a H bridge circuit, processor 30 is connected respectively to four inlet opening A, B, C, the D of H bridge circuit by port P11, P9, P10, P6, these four inlet openings are connected with power switch component Q4, Q1, Q2, Q3 by resistance R 4, R1, R2, R3 respectively, electromagnet apparatus 5 is connected between the tie point L of the tie point H of power switch component Q1 and Q2 and power switch component Q3 and Q4, and a termination cell bag power supply of H bridge circuit, the other end ground connection.In the present embodiment, above-mentioned power switch is a semiconductor switch, and is preferably MOSFET.Processor is controlled electromagnet apparatus 53 by break-make four inlet opening A, B, C, D.For example, when inlet opening A, B connect, and inlet opening C, D are when disconnecting, power switch component Q1 and Q4 connect, this moment, the flow direction of electric current was to tie point L from tie point H, correspondingly, the push rod 535 of electromagnet apparatus 53 drives ring gears 45 and moves to low-speed position shown in Figure 11 from as shown in figure 10 high speed position.Otherwise when inlet opening A, B disconnect, and inlet opening C, D be when connecting, and the push rod 535 of electromagnet apparatus 53 drives ring gear 45 and moves to high speed position from low-speed position.

Gear signal feeder loop 34 comprises a switch 387, and resistance R 25, R26, R27, R28.In the present embodiment, switch 387 is a hilted broadsword on off switch, and it comprises contact H1 and contact L1, and wherein, the port one 3 of contact L1 and processor is connected, and the port one 4 of contact H1 and processor is connected.For what those of ordinary skill in the art can expect easily be, during concrete enforcement, contact H 1 and contact L1 can be arranged on the reed at the gear frame stroke two ends on the casing, then be provided with tinsel on the gear frame, as copper sheet, when gear frame moved to high speed position, its tinsel contacted and make contact H1 with corresponding reed; Otherwise, make contact L1 then.As shown in figure 20, when gear frame moved to low-speed position, contact H1 was disconnected and contact L1 is switched on, at this moment, port one 3 can detect a low level signal, and port one 4 can detect a high level signal, thereby the present gear drive of processor 30 judgements is worked under high reduction speed ratio; Otherwise after gear frame turned back to high speed position, port one 4 can detect a low level signal, and port one 3 can detect a high level signal.For what those of ordinary skills can expect easily be, but tinsel and reed relative set or are arranged on the push rod and housing of electromagnet apparatus on ring gear and gear-box.

In the present embodiment, what functional switch 36 adopted is the velocity mode switch of changeable three kinds of velocity modes as shown in figure 16, promptly switches between fast mode, low-speed mode and automatic mode.As shown in figure 20, velocity mode switch 36 is hilted broadsword three-position switches, and it has three contact L2, H2, A, is connected to port P26, P25, the P24 of processor respectively by resistance R 14, R15, R16.When velocity mode switch 36 is positioned at as shown in FIG. position, be that contact A is connected, and contact H2 and contact L2 disconnect, at this moment, it is low level signal that processor 30 detects port P24, and port P25, P26 are high level signal, and so, processor will call and move the program (follow-up will being described in detail this) of automaitc shfit.And when the contact A disconnection, when contact H2 or contact L2 connected, processor 30 can not call and move the program of automaitc shfit.

Two switch S 2 of signal occurrence device 35, S3 parallel connection, and be connected with the port P23 of processor 30 by resistance R 17.When any is depressed among switch S 2, the S3, will produce an electrical signal and pass through port P23 input processor 30, so, processor 30 will interrupt the program of moving at present and call speed changeover program (following will being described in detail).

Next, the workflow that cooperates Figure 21 and Figure 22 to switch with execution self-shifting workflow that processor is described respectively and speed.

With reference to Figure 21, cooperate simultaneously with reference to shown in Figure 20, after main switch 13 closures (step 711), processor port P1 receives reset signal, thus processor is carried out initialization action (step 712).Then, processor is gathered the voltage signal (step 713) of cell bag by port 3, to judge but whether cell bag is in the state of normal use, judge that promptly whether cell bag voltage is less than 12.5V, if, show that cell bag through putting, is unsuitable for discharging again, thereby can blocks port P12 output pwm signal; If not, show that cell bag can normally use, next, detection speed mode switch 36 present selected patterns (step 714).If what velocity mode switch 36 was selected is automatic mode, judge further then whether electromagnet apparatus 53 is in high speed position (step 715), if then continue next step; If not, then processor is connected inlet opening C, D, and disconnects inlet opening A, B, moves to high speed position (step 718) thereby drive push rod to electromagnet apparatus 53 logical back currents.If what velocity mode switch 36 was selected is fast mode, judge further then whether electromagnet apparatus is in high speed position (step 716), if then continue next step; If not, DM device and impel push rod to move to high speed position (step 719) then.If what velocity mode switch 36 was selected is low-speed mode, judge further then whether electromagnet apparatus is in low-speed position (step 717), if then continue next step; If not, then processor disconnects inlet opening C, D, and connects inlet opening A, B, moves to low-speed position (step 720) thereby drive push rod to the logical forward current of electromagnet apparatus.

Next, show the dump energy (step 721) of cell bag by LED lamp D2-D5, and when the electric weight wretched insufficiency electric power of sever supply motor; Detect in real time the voltage (step 722) of cell bag, and cross the electric power of sever supply motor when putting in cell bag; Detect according to pressing depth (step 723) of trigger; According to pressing depth export corresponding pwm signal (step 724) according to trigger; Detect motor current (step 725).

Judge velocity mode (step 726), if control system operates in fast mode or low-speed mode at present, judge then whether motor current continues 500ms (millisecond) greater than 90A (ampere) (step 727,729), if, show that motor abnormal case such as stall might take place and causes electric current excessive, therefore, be the protection motor, disconnect the electric current (step 728,730) of supply motor; If not, then return step 721.If control operates in automatic mode, judge then whether motor current continues 300ms (millisecond) greater than 90A (ampere) (step 731), if show that stall might take place motor, then carries out the step of automaitc shfit; If not, continue then to judge whether motor current continues 500ms (millisecond) greater than 30A (ampere) (step 732), if, show that the efficient that instrument is exported at a high speed is about to be lower than the efficient that low speed is exported, like this then carry out the step of automaitc shfit; If not, then return step 721.

In the present embodiment, automaitc shfit step comprises step 733-step 736.At first,, temporarily stop to provide electric power (step 733) to motor for avoiding beating tooth, i.e. processor temporary interruption port P12 output signal, thus the speed drop of motor and ring gear is got off.Then, processor control H bridge circuit is to the logical forward current of electromagnet apparatus, be that processor is connected inlet opening A, B, and disconnection inlet opening C, D, thereby make electromagnet apparatus drive push rod and move to low-speed position (step 734) from high speed position, and when moving to low-speed position, trigger switch S5 and contact L1 is connected.Then, soft start motor (step 735), promptly processor progressively increases the pulsewidth of voltage signal by the pwm signal of port P12 output, thereby impels motor to be returned to normal running speed at leisure.Again, the low level signal that processor receives according to port one 3 is set low speed mark (step 736), next, returns step 721.Need to prove, need a period of time owing to ring gear moves to low-speed position from high speed position under the driving of push rod, so, in other embodiments, also can be by processor elder generation DM device, the step of suspending at motor then.In this process, only need guarantee that motor driven power does not exist before ring gear and whirl-stop device engagement, so, even the speed of ring gear does not also drop to zero, but because it does not have the driving force of active rotation, so, can be with whirl-stop device engagement and staticly get off very soon.

With reference to Figure 22, and cooperate with reference to shown in Figure 20, when the port 23 of processor received an interrupt signal, processor can stop the program of moving at present and call speed changeover program (step 751).Processor at first detects motor currents whether excessive (step 752) by port 21, as greater than 100A (ampere), if, show motor stall, then stop to motor supplying electric current (step 753); If not, then which kind of pattern (step 754) the detection speed mode switch is at present.If automatic mode then interrupts returning, promptly processor continues to carry out original program (step 767); If fast mode or low-speed mode need then to judge whether motor is in zero load.Since when load is arranged during with respect to zero load motor speed to reduce ground faster, so when having compared load, after motor power cuts off when unloaded, need the longer time that motor is stopped.If fast mode judges that whether motor current continues 500ms (millisecond) greater than 30A (ampere) (step 755), if showing has load, stops the electric power of supply motor subsequently and postpones 0.5S (step 756); If not, then stop the electric power of supply motor and postpone 2S (step 757).If low-speed mode judges that whether motor current continues 500ms (millisecond) greater than 30A (ampere) (step 761), if showing has load, stops the electric power of supply motor subsequently and postpones 0.5S (step 762); If not, then stop the electric power of supply motor and postpone 2S (step 763).Carrying out the shutdown delay; next processor DM device is carried out from a high speed to low speed or switching from low speed to high speed (step 758,764); starting motor (step 759,765) subsequently; and respective settings low speed mark or high speed mark (step 760,766), then return original program (step 767).

Figure 23 a, 23b and 24 have disclosed the another kind of mode of execution of speed change tool of the present invention.Contrast to the difference of mode of execution be that in this mode of execution, drive unit comprises small motor 55 and is used to transmit a driving mechanism of the rotation output of small motor.This driving mechanism comprises pinion drive mechanism 56 with an output shaft 561, is fixedly installed on the gear 57 on the output shaft 561 in the present embodiment, and a circular sleeve 58 that can be rotatably set in gear-box 47 outsides.Above-mentioned small motor 55 and pinion drive mechanism 56 be meant with respect to traditional motor and gear drive, and as motor 2 and gear drive 4, its size reduces greatly to think and satisfies special applications and designed motor and gear drive.Circular sleeve 58 has a pair of guide slot that relatively is arranged on its peripheral wall, is used for accommodating and guide wire cover 513 two terminal relatively.Circular sleeve 58 also has the external tooth 584 that is arranged on its peripheral wall outer surface, in order to cooperate with gear 57.Each guide slot comprises first, second section 581,583 that is basically perpendicular to an axis (shown in the dotted line of Figure 23 a and 23b), and the 3rd section 582 of extending between first and second section 581,583 and along axis tilt.

What Figure 23 a, 23b represented respectively is that speed change tool is under high speed and the lower-speed state in the present embodiment.When starting small motor 55, the gear 57 that fixedly installs with respect to output shaft 561 obtains a rotational speed, and by with 584 of the external tooths of circular sleeve 58 cooperate drive spool 58 rotations.It should be noted that in the present embodiment that steel wire cover 513 can only be arranged in the gear-box 47 along the mode that axial direction moves.Thereby when circular sleeve 58 rotation, steel wire cover 513 the 3rd sections 582 of being guided groove order about and motion vertically, thereby and moving part 45 move to another velocity location from a velocity location vertically with steel wire cover 513 and realize automatic speed changing.With before mode of execution, small motor can be connected in the H bridge circuit, and by microprocessor control, the current direction that is applied on the H bridge circuit by change changes the sense of rotation of motor, thereby realizes at a high speed and the switching between the low speed.In addition, what those of ordinary skill in the art can expect easily is, if the output torque of the small motor that adopts is enough big, can save pinion gear system, so, can reach the effect that speed is switched equally.

Figure 25 and shown in Figure 26 be another mode of execution of the drive unit of electric tool of the present invention.With a last mode of execution similarly be, actuator still adopts small motor 55, but driving mechanism is different.As shown in figure 25, in the present embodiment, driving mechanism comprises the screw rod 565 that driven by small motor 55 rotation, is arranged between screw rod 565 and the steel wire cover 513 and can be driven and linear mobile carriage 575 and the guiding seat 586 that is used for guide bracket 575 by screw rod 565.As shown in figure 26, screw rod 565 extends setting vertically, and the one end is set on the output shaft (not indicating) of small motor 55, and the other end is by a coupling sleeve 566 rotatable being arranged on the guiding seat 586.On the body of rod between the two ends of screw rod 565, convex with continuous helical burr 5651.Guiding seat 586 is fixedly installed on the bottom of gear-box 47, and it is formed with the guide rail 587 that extends vertically.Carriage 575 comprises base 576 and a pair of side arm 577 that is extended upward by base 576 both sides, and the top of each side arm is concaved with draw-in groove 5771, can correspondingly accommodate the end of steel wire cover 513.The top of the base 576 of carriage 575 is formed with guide slot 5761, can cooperate and slippage vertically with the guide rail 587 of guiding seat 586.The bottom notch of base 576 is formed with vertically the groove 5762 that extends, and further is recessed to form the helical burr 5651 corresponding spiral chutes that cooperate 5763 with screw rod 565 on the inwall of groove 5762.

After small motor 55 started, screw rod 565 was driven in rotation, and carriage 575 is driven by screw rod 565 then, owing to be subjected to the guiding of guiding seat 586 guide rails 587, carriage 575 is linear vertically to be moved, and further drives steel wire cover 513 property along the line and moves.Thereby, but the rotation implementation tool by small motor 55 is at a high speed and the switching between the low speed.Mode of execution as described above, small motor can be connected in the H bridge circuit, and by microprocessor control, the current direction that is applied on the H bridge circuit by change changes the sense of rotation of motor, thereby realize at a high speed and the switching between the low speed.

Gear drive among the present invention and moving part thereof are not limited to the structure that present embodiment discloses, gear engagement relation when particularly being not limited to present embodiment high speed retaining and bottom gear, gear drive in the prior art is various, announce No. 6796921 as U. S. Patent and disclosed multiple gear drive, meshing relation when its top gear and bottom gear has nothing in common with each other, but those of ordinary skills are easy to inventive concept according to the present invention various gear drives is applied to the present invention.

Claims (17)

1. speed change tool, it is characterized in that: this instrument comprises

Casing;

Motor is arranged in the casing, and outputting rotary power;

Output shaft;

Gear drive is arranged between motor and the output shaft, and is delivered on the output shaft with one in the plurality of gears reduction speed ratio that comprises first gear reduction ratio and the second gear reduction ratio at least rotation output with motor, and described gear drive comprises

At least one group of train of gearings, and

Moving part cooperates changeably with described train of gearings, and described moving part can and the corresponding primary importance of first gear reduction ratio and and the corresponding second place of second gear reduction ratio between move;

Control system, it comprises drive unit, is used to drive described moving part and moves to the second place from primary importance, also is used to drive described moving part and moves to primary importance from the second place.

2. speed change tool according to claim 1 is characterized in that: described drive unit comprises a small motor and the driving mechanism that the rotation output of small motor is passed to moving part.

3. speed change tool according to claim 2 is characterized in that: described driving mechanism comprises sleeve, is arranged on the pinion drive mechanism between small motor and the sleeve.

4. speed change tool according to claim 3 is characterized in that: described sleeve is driven by the rotation of described pinion drive mechanism.

5. according to claim 3 or 4 described speed change tools, it is characterized in that: described gear drive comprises the steel wire cover that cooperates with the moving part axial restraint, and described sleeve is provided with guide slot with respect to axioversion to accommodate and to guide described steel wire cover along its peripheral wall.

6. speed change tool according to claim 4 is characterized in that: described moving part moves in the rotation driving lower linear of described sleeve.

7. speed change tool according to claim 2 is characterized in that: described driving mechanism comprises the screw rod that is driven by small motor rotation, and the carriage that moves by bolt rod driving and as axial linear.

8. speed change tool according to claim 7 is characterized in that: described gear drive comprises the steel wire cover that cooperates with the moving part axial restraint, and described carriage and described steel wire overlap axial secure fit.

9. speed change tool according to claim 7 is characterized in that: convex with the spirality burr on the described screw rod, described carriage is provided with the spiral slot that cooperates with described burr.

10. speed change tool according to claim 7 is characterized in that: described driving mechanism also comprises the guiding seat that is fixedly installed in the casing, and described guiding seat is provided with guide rail, and described carriage is provided with the guide slot that cooperates with described guide rail.

11. speed change tool according to claim 1 is characterized in that: described train of gearings comprises planetary gear train, and described planetary gear train comprises several rows star-wheel and the planet carrier that is used to support planet wheel.

12. speed change tool according to claim 11 is characterized in that: described moving part comprises ring gear, and when primary importance, described ring gear meshes with described planet wheel and planet carrier simultaneously; When the second place, described ring gear only meshes with described planet wheel.

13. speed change tool according to claim 12 is characterized in that: described gear drive comprises the whirl-stop device that fixedly installs with respect to casing, and when the second place, described moving part cooperates with described whirl-stop device and keeps relative fixed with casing.

14. speed change tool according to claim 1 is characterized in that: described control system comprises electronic control unit, and described electronic control unit drives described moving part and moves between the primary importance and the second place by applying electric current for described drive unit.

15. speed change tool according to claim 14 is characterized in that: described electronic control unit also comprises the H bridge circuit, can be used for changing the moving direction that the current direction that imposes on drive unit changes described moving part.

16. speed change tool according to claim 1 is characterized in that: speed change tool also comprises the chuck that is connected with output shaft.

17. speed change tool according to claim 1 is characterized in that: speed change tool also comprises trigger, and described trigger and motor electrically connect, and the degree of depth that described trigger is pressed and the rotational speed of motor are proportional.

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