CN102126035A

CN102126035A - Electric tool

Info

Publication number: CN102126035A
Application number: CN201010005260XA
Authority: CN
Inventors: 钟红风; 何明明
Original assignee: Positec Power Tools Suzhou Co Ltd
Current assignee: Positec Power Tools Suzhou Co Ltd
Priority date: 2010-01-14
Filing date: 2010-01-14
Publication date: 2011-07-20

Abstract

The invention relates to an electric tool. The electric tool comprises a shell, a motor, a first transmission part, a second transmission part, a clutch, an output shaft and a speed regulation element, wherein the motor is arranged in the shell and provides rotary power; the first transmission part is connected with the motor, receives input torque output by the motor, and comprises a first planet carrier, and a first internal gear ring provided with a chute; the second transmission part is connected with the first transmission part and comprises a second internal gear ring; the clutch is arranged between the second transmission part and the shell, and restricts the rotation of the second internal gear ring when the input torque is greater than a preset value; the output shaft is connected with the second transmission part; the speed regulation element is partially accommodated in the chute; and when the input torque is greater than the preset value, the first internal gear ring rotates to allow the speed regulation element to axially move along the first internal gear ring, and drives the second internal gear ring to move from a first position at which the second internal gear ring is engaged with a second planet gear and the first planet carrier simultaneously to a second position at which the second internal gear ring is engaged with the second planet gear and is disconnected from the first planet carrier, so that the output shaft outputs different rotating speeds. Compared with the prior art, the electric tool has a stable structure and is easy to operate.

Description

Electric tool

Technical Field

The present invention relates to an electric power tool having an automatic speed change transmission.

Background

Dc power drills are commonly used for drilling and screwing. In the process of executing tasks, the torque born by the electric drill can change, and in order to protect the motor from overload and burnout in different torque states, the electric drill is provided with a control mechanism for controlling a transmission device of the electric drill to generate different outputs under the conditions that the torque is smaller than a certain preset value and exceeds the certain preset value. For example, chinese patent publication CN101117999A discloses a variable speed transmission of an electric tool, which can change the output speed of the electric tool according to the increase of torque. By providing the annular connector to move between two predetermined positions, the power tool transmission can achieve automatic speed change. However, since the ring connector needs to be moved frequently, and receives an impact from the ring gear in the axial direction, the structural strength of the connector is low.

Disclosure of Invention

The invention provides an electric tool with a transmission device with high structural strength.

In order to achieve the purpose, the technical scheme of the invention is as follows: a power tool, comprising: a housing; the motor is arranged in the shell and provides rotary power; the first transmission part is connected with the motor, receives input torque output by the motor, and comprises a first planet carrier and a first inner gear ring with a chute; the second transmission part is connected with the first transmission part and comprises a second inner gear ring; the clutch is arranged between the second transmission part and the shell, and the second inner gear ring is limited to rotate when the input torque is larger than a preset value; the output shaft is connected with the second transmission part; the electric tool further comprises a first elastic element arranged between the machine shell and the first inner gear ring, a second elastic element arranged between the machine shell and the second inner gear ring, and a speed regulating element partially accommodated in the chute, wherein when the input torque is greater than a preset value, the first inner gear ring rotates against the acting force of the first elastic element, so that the speed regulating element moves in the chute along the axial direction of the first inner gear ring under the action of the second elastic element, the second inner gear ring is driven to move from a first position, which is simultaneously meshed with the second planet wheels and the first planet carrier, to a second position, which is meshed with the second planet wheels and is disengaged from the first planet carrier, and the output shaft outputs different rotating speeds.

Preferably, the electric tool includes a forward/reverse switching knob for controlling a rotation direction of the motor, and a clutch switching plate is provided between the clutch and the forward/reverse switching knob to allow the clutch to act in a single direction. Furthermore, the clutch comprises an outer ring connected with the shell, an inner ring connected with the second inner gear ring and a rolling body arranged between the outer ring and the inner ring.

Preferably, the first ring gear has an annular main body, and an outer circumferential surface of the annular main body is provided with a sliding groove including a continuous path formed by a circumferential groove, an axial groove, and an inclined groove. Furthermore, a rotating block is arranged in the sliding groove, the rotating block is provided with a main body which is basically triangular or right trapezoid, and the side edge of the main body and the inner wall of the sliding groove jointly form a circumferential groove, an axial groove and an inclined groove.

Preferably, the first inner gear ring is provided with an annular groove, and the elastic element is accommodated in the annular groove to resist the rotation of the first inner gear ring. Further, the elastic element is a compression spring.

Preferably, an axial end face groove is formed in the end face of the first inner gear ring, a containing hole is formed in the machine shell and used for containing a positioning spring and a positioning pin, and after the input torque exceeds a preset value, the positioning pin is combined with the end face groove under the action of the positioning spring and the first inner gear ring, so that the second inner gear ring is stably kept at the second position. Further, the electric tool comprises a switch, the switch is provided with a motor switch, a switch trigger and a switch shifting block, and before the switch trigger triggers the motor switch, the switch shifting block shifts the positioning pin to be disengaged from the end face groove, so that the second inner gear ring is stably kept at the first position.

Preferably, the speed regulating element is a pin, the gear shifting plate is sleeved outside the second inner gear ring, the gear shifting steel wire is connected between the gear shifting plate and the second inner gear ring, and the pin penetrates through the rear part of the gear shifting plate and is accommodated in a sliding groove in the first inner gear ring.

Compared with the prior art, the speed regulating device has the advantages that the speed regulating element partially accommodated in the first inner gear ring is arranged, so that the rotation of the first inner gear ring causes the movement of the second inner gear ring, the change of the output speed of the transmission device is realized, the structure is stable, and the operation is simple.

Drawings

The invention is further described with reference to the following figures and embodiments.

Fig. 1 is a schematic view of a first embodiment of a power tool having a transmission.

Fig. 2 is a schematic view of the electric power tool shown in fig. 1, in which the second ring gear is in a low position.

Fig. 3 is a schematic view of the power tool of fig. 1, with the second ring gear in a top gear position.

Fig. 4 is an operation schematic diagram of the first ring gear and the torque adjusting mechanism, wherein the first ring gear and the reset plate do not move relatively.

Fig. 5 is an operation diagram of the first ring gear and the torque adjusting mechanism, wherein the first ring gear rotates a certain angle relative to the reset plate.

FIG. 6 is a partial cross-sectional schematic view of the power tool taken along line A-A of FIG. 1, wherein the transmission is in a top gear position.

FIG. 7 is a partial cross-sectional schematic view of the power tool taken along line A-A of FIG. 1, with the transmission in a low gear position.

Fig. 8 is a schematic view of the second ring gear in the low position.

FIG. 9 is a schematic view of the second ring gear in a top gear position.

Fig. 10 is a schematic view of the second ring gear in the incomplete reset position.

FIG. 11 is a schematic illustration of the clutch and switch knob action with the switch knob in a forward gear position.

FIG. 12 is a schematic illustration of the clutch and shift knob action with the shift knob in a reverse gear position.

FIG. 13 is a partial cross-sectional view of the control mechanism taken along line B-B of FIG. 1, with the shift slider in contact with the deadbolt.

Fig. 14 is a partial cross-sectional view of the control mechanism taken along line B-B of fig. 1, wherein the deadbolt is angularly deflected.

FIG. 15 is a partial cross-sectional view of the control mechanism taken along line B-B of FIG. 1, with the deadbolt in a disengageable position with the shift slider.

FIG. 16 is a partial cross-sectional view of the control mechanism taken along line B-B of FIG. 1, with the deadbolt disengaged from the shift slider.

FIG. 17 is a partial cross-sectional view of the control mechanism taken along line B-B of FIG. 1 with the hook slide returned.

FIG. 18 is a partial cross-sectional view of the control mechanism taken along line B-B of FIG. 1, with the deadbolt returned to a position of contact with the shift slider.

FIG. 19 is a schematic view of a second embodiment of a power tool having a transmission, wherein the transmission is in a top gear position.

FIG. 20 is a second embodiment of the power tool having a transmission, wherein the transmission is in a low gear position.

Fig. 21 is a perspective view of the first ring gear in fig. 19.

Fig. 22 is a schematic cross-sectional view of the transmission taken along line C-C of fig. 19.

Fig. 23 is a schematic cross-sectional view of the transmission taken along line D-D in fig. 20.

Fig. 24 is an exploded schematic view of a portion of the transmission of fig. 19.

Fig. 25 is a schematic view showing the pin of the gearshift moving in the M-shaped groove while the first ring gear is rotated against the elastic force of the compression spring when the load variation of the electric tool of fig. 19 does not reach the predetermined value.

Fig. 26 is a schematic view showing that when the load variation of the electric tool of fig. 19 reaches a predetermined value, the first ring gear further rotates against the elastic force of the compression spring, and the pin of the gearshift mechanism axially moves forward along the axial groove of the first ring gear under the tensile force of the gearshift return spring.

Fig. 27 is a schematic view showing the electric power tool of fig. 19 in which the first ring gear is restored by the compression spring and the pin of the shifting mechanism is axially moved backward along the inclined groove of the first ring gear against the elastic force of the shift restoring spring. Wherein,

40 electric drill 42 motor 44 power supply

41 casing 43 armature shaft 46 transmission device

47 output shaft 96 switch shifting block 148 shifting block

48 tool chuck 97 Motor switch 178 annular body

Internal teeth of switch trigger 179 of 49 tool 98

50 switch 100 switch spring 180 shift plate

52 handle 101 motor receiving cavity 182 pin

54 first drive 102 gearbox housing 184 turning block

56 first center wheel 104 thumb latch 185 rotation shaft

58 first planetary gear 106 slide post 186M shaped recess

60 first planet carrier 108 circlip 187 rotation hole

62 first internal tooth 110 hooking slider 188 arc-shaped groove

64 second transmission part 112 stop block 190 end face

66 second center wheel 114 lug 192 compression spring

68 end surface groove of annular gear shifting fork 194 of second planet gear 116

70 second planet carrier 118 shift arm 196T-shaped pin

72 second ring gear 120 cam surface 198 detent spring

74 Shift slider 122 cam slot 200 body portion

76 Shift Steel wire 128 Clutch fork 202 chute

78 Shift Return spring 130 Clutch switch plate 204 axial slide groove

80 spring 132 shift knob 206 circumferential slide groove

82 reset plate 134 third transmission part 208 oblique sliding groove

84 Clutch 136 third center wheel 246 Transmission

86 clutch outer 138 third planet gear 254 first drive

88 rollers 140 third planet carrier 262 first ring gear

90 clutch inner 142 third ring gear 264 second transmission part

92 hook pin 144 control mechanism

94 hook spring 146 projection

Detailed Description

Referring to fig. 1-18, a first embodiment of the present invention. A power drill 40 includes a housing 41, a motor 42 housed in the housing 41, a power source 44 for supplying power to the motor 42, a switch 50 connected to the power source 44 for starting/stopping the motor 42, a transmission 46 driven by the motor 42, an output shaft 47 connected to the transmission 46, a tool holder 48 connected to the output shaft 47, and a tool 49 housed in the tool holder 48. The drill 40 also includes a handle 52 located between the housing 41 and the power source 44. In this embodiment, the power source is a battery pack, for example, a lithium battery pack may be used. Of course, nickel-cadmium, nickel-metal hydride battery packs, and the like are also possible.

The housing 41 includes a motor receiving chamber 101 and a reduction gear housing 102. The motor 42 is accommodated in the motor accommodating chamber 101. The motor 42 has an armature shaft 43, outputting a rotary motion. The reduction gear housing 102 is connected to the motor accommodating chamber 101 and accommodates the transmission 46.

The transmission 46 comprises an armature shaft 43 connected to a motor 42, the motor 42 driving the armature shaft 43 to rotate when a switch 50 is activated, the rotational energy of which is transmitted from the armature shaft 43 to an output shaft 47 via the transmission 46. The transmission 46 is capable of changing the rotational speed from the electric pivot shaft 43 to the output shaft 47 in response to a predetermined input torque. In the present embodiment, the transmission 46 includes a first transmission portion 54, a second transmission portion 64, and a third transmission portion 134. The first transmission 54 has a first center wheel 56, a first planetary wheel 58, a first carrier 60, and a first ring gear 62. The second transmission part 64 has a second central gear 66, second planet gears 68, a second planet carrier 70 and a second annulus gear 72. The third transmission 134 has a third center wheel 136, a third planet wheel 138, a third carrier 140, and a third ring gear 142. The first center wheel 56 is fixed to the armature shaft 43 and outputs the same rotational speed as the motor. The second sun gear 66 is fixedly connected to the first carrier 60, and both output the same rotational speed. The third sun gear 136 is fixedly connected to the second carrier 70, and both output the same rotational speed.

A first elastic element 80 and a reset plate 82 are disposed between the motor 42 and the first transmission part 54. Specifically, in the first embodiment, the spring 80 is supported in the reduction case housing 102 to be elastically deformable in the axial direction of the armature shaft 43. When tool 49 is not under load, spring 80 holds first ring gear 62 in the initial position by the cam surface on reset plate 82. When the load applied to the tool 49 changes, the load force is transmitted to the first ring gear 62 along the transmission chain, driving the first ring gear 62 to rotate against the holding force of the spring 80 acting on the first ring gear 62 through the cam surface of the reset plate 82. When the load on tool 49 changes, the force applied by spring 80 changes accordingly, and thus affects the position of first ring gear 62, so that control mechanism 144 acts to move shift block 74 and adjust the rotational speed and torque output by transmission 46 to operate tool 49 at the proper torque and rotational speed under different load conditions.

The first ring gear 62 is an annular member whose inner circumferential surface has teeth that mesh with the first planetary gears 58. An outer circumferential surface of the first ring gear 62 is formed with a ring gear shifter 116. Referring to fig. 4 and 5, the outer surface of the first ring gear 62 is provided with a cam groove 122, and in particular, the cross-sectional shape of the cam groove 122 is V-shaped. Those skilled in the art will appreciate that the cam slot 122 may have other shapes, such as curved, etc.

The first planet carrier 60 comprises a disc-shaped body and a holder extending from one side of the body, and a second sun wheel 66 extending from the opposite side of the body and engageable with a second planet wheel 68. The outer circumferential surface of the first carrier 60 is provided with a plurality of radial protrusions spaced apart from each other to be engaged with or disengaged from the second ring gear 72, so that the second ring gear 72 is locked to the first carrier 60 when it is at the first position, and at this time, the first carrier 60 rotates at the same speed as the second ring gear 72 and the second sun gear 66, and the output shaft 47 rotates at a high speed. And when the second ring gear 72 is in the second position, it moves relatively independently of the first carrier 60, and the rotational speed of the output shaft 47 is low.

The first planetary gear 58 is fitted over the holder while being engaged with the first ring gear 62 and the first center gear 56. The retaining member is a cylindrical pin disposed parallel to the axis of the armature shaft 43. The first planetary gear 58 transmits the rotation of the armature shaft 43 to the first carrier 60 via the holder, and at this time, the first transmission portion 54 outputs the first rotation speed.

The second ring gear 72 is an annular member having internal teeth on its inner circumferential surface that mesh with the second planet gears 68. The outer circumferential surface of the second ring gear 72 has grooves for coupling with the shift wire 76. The outer circumferential surface of the second ring gear 72 is also provided with a plurality of clamping grooves which are arranged at intervals in the circumferential direction and are always meshed with a plurality of lugs which are arranged at intervals in the circumferential direction and are arranged on the clutch inner ring 90 of the clutch 84 arranged on the reduction gearbox shell 102. The second ring gear 72 is axially movable in the axial direction of the armature shaft 43 so as to be located at a first position locked with the first carrier 60 and a second position disengaged from the first carrier 60. The second annulus gear 72 remains engaged with the second planet gears 68 throughout its axial movement relative to the first planet carrier 60.

The second planet carrier 70 comprises a disc-shaped body and a plurality of holders extending from one side of the body, and a third central wheel 136 extending from the opposite side of the body and engageable with a third planet wheel 138. The second carrier 70 is disposed coaxially with the first carrier 60.

Third ring gear 142 is an annular member whose inner circumferential surface has internal teeth that mesh with third planetary gears 138. The outer circumferential surface thereof is supported in the reduction gear case 102 so that the third ring gear 142 can rotate in the reduction gear case 102.

The third planet carrier 140 includes a disc-shaped body and a plurality of holders extending from one side of the body, and the third center wheel 136 is engaged with the third planet wheel 138. The third carrier 140 is engaged with the output shaft 47, transmitting the rotational output of the third transmission portion 134 to the output shaft 47.

The shift mechanism 73 is used to automatically switch the output speed of the output shaft in response to a change in load. The shift mechanism includes a switching unit and a control unit. The switching unit comprises a gear shifting slider 74 arranged outside a reduction box shell 102, a gear shifting steel wire 76 connected with the gear shifting slider 74 and the second ring gear 72, and a gear shifting return spring 78 connected with the reduction box shell 102 and the gear shifting slider 74. Under the action of the control unit, the shifting unit moves the second ring gear 72 into a first position locked with the first carrier 60 and a second position disengaged from the first carrier 60. Causing the transmission 46 to output a different rotational speed.

The shift block 74 is substantially annular and is disposed on the outer surface of the reduction gearbox housing 102. The shift slider 74 has an outer circumferential surface provided with a receiving groove for partially receiving the shift wire 76. The outer circumferential surface of the shift slider 74 is further provided with a plurality of hooks extending radially outward, and the outer circumferential surface of the corresponding reduction case housing 102 is also provided with a plurality of hooks extending radially outward. The shift return spring 78 is disposed between the shift slide 74 and the reduction housing 102. In this embodiment, the shift return spring 78 is a tension spring having one end hooked to a hook on the shift slider 74 and the other end hooked to a hook on the gear box housing 102. The shift slider 74 is axially movable along the armature shaft 43 against the pulling force of the shift return spring 78, which in turn axially moves the shift wire 76 along the armature shaft to axially move the second ring gear 72.

The gear shifting steel wire 76 is semi-annular, the annular main body part is accommodated in the accommodating groove on the gear shifting slider 74, two end parts are bent inwards in the radial direction and clamped with the clamping groove arranged on the outer circumferential surface of the second inner gear ring 72 to drive the second inner gear ring 72 to move axially, so that the transmission device 46 outputs different rotating speeds.

The switch 50 is disposed between the reduction gear housing 102 and the handle 52 and includes a motor switch 97, a switch trigger 98 that the operator presses to activate the motor switch 97, a switch pusher 96 connected to the switch trigger 98, and a switch spring 100 that compresses and returns under the action of the operator's pressure.

The control unit adjusts the state of the switching unit in response to a change in load borne by the electric drill tool. In this embodiment, the control unit includes a shift pin 104 selectively engageable with and disengageable from the shift block 74, a hook block 110 supporting the shift pin 104 on the reduction gear housing 102, and a hook spring 94 disposed between the hook block 110 and the switch block 96. The driver pin 104 is rotatably mounted on a hook slide 110 via a slide support 106 and a latch spring 108. When the load received by the spring 80 exceeds a predetermined torque value, the cam surface 120 of the reset plate 82 and the cam groove 122 of the first ring gear 62 are relatively displaced, and thus the first ring gear 62 is rotated by a certain angle about the axis of the armature shaft 43. The ring gear shift fork 116 will drive the shift pin 104 to rotate around the axis of the slider post 106, and the protrusion 114 on the shift slider 74 is angularly offset from the shift arm 118, so that the shift pin 104 can be disengaged from the shift slider 74, and the shift slider 74 returns to the initial state of rest under the action of the shift return spring 78. The hooking slider 110 is provided therein with a hooking pin 92 penetrating the hooking slider 110 in a longitudinal extension direction of the hooking slider 110. One end of the hanger pin 92 is provided with a stopper 112. One end of the hook spring 94 abuts against the end surface of the hook slider 110 and the other end abuts against the stopper 112. The stop 112 abuts against the switch block 96, and under the urging of the switch block 96, the hook pin 92 is urged to move against the action of the hook spring 94, and further the shift pin 104 is urged to move after the hook pin 82 has moved a certain distance.

The various positions of the shifter 73 of the drill 40 of the first embodiment will now be described and explained with reference to fig. 1-3. The drive 46 of the power drill 40 is at rest in figure 1. At this time, the switch trigger 98 is not yet pressed, and the control unit cannot move the switching unit. Under the action of the shift return spring 78, the shift slider 74 is in the first position, and the second ring gear 72 is engaged with the second planet gears 68 and disengaged from the first planet carrier.

If the operator presses the switch trigger 98, which compresses the switch spring 100, and at the same time, the switch block 96 pushes against the stop 112, compressing the hook spring 94, and the latch arm 118 has a tendency to pull the shift slider 74 toward the high gear.

As shown in fig. 2, when hook spring 94 is compressed to a degree that the spring force thereof is greater than the spring force of shift return spring 78, and switch trigger 98 is continuously pressed, shift arm 118 pulls shift slider 74 to move axially along the armature shaft, thereby moving second ring gear 72 toward first transmission part 54. As shown in fig. 3, with continued depression of the switch trigger 98, the shift arm 118 pulls the shift slide 74 to move the second ring gear 72 into engagement with the first carrier 60 with the drill drive 46 in the top gear position.

Continuing to depress the switch trigger 98, the switch 50 will be closed and the motor 42 will be energized in communication with the power source 44. Thus, when the switch 50 activates the motor 42, the power drill 40 moves the transmission 46 to the high gear position and the output shaft 47 outputs a high rotational speed.

Referring to fig. 4-5, as the load applied to tool 49 increases, reset plate 82 rotates relative to first ring gear 62 such that cam slots 122 in first ring gear 62 do not fully engage cam surfaces 120 in reset plate 82. Referring to fig. 6 and 7 together, the first ring gear 62 rotates a certain angle to make the ring gear shift fork 116 shift the shift pin 104, the shift pin arm 118 is disengaged from the protrusion 114 on the shift slider 74, and the shift slider 74 moves the second ring gear 72 from the high gear position to the low gear position, i.e., to the position disengaged from the first carrier 60, under the action of the shift return spring 78.

Referring to fig. 8-10, the second ring gear 72 is shifted from a low gear to a high gear during start-up. Fig. 8 shows the second ring gear 72 in a low speed state, disengaged from the first carrier 60 and engaged with the clutch inner 90. Before motor 42 is activated, shift arm 118 contacts shift slider 74 and the operator presses switch trigger 98 to move second ring gear 72 from low to high, i.e., to move the engagement teeth on second ring gear 72 into engagement with the radial recesses on first carrier 60 as shown in FIG. 9. Of course, there are few cases where the end surfaces of the engaging teeth of the second ring gear 72 contact the end surface of the first carrier 60 and cannot engage with the recesses of the first carrier 60 when the power drill 40 is turned on, as shown in fig. 10, and at this time, the second ring gear 72 rotates to engage with the first carrier 60 after the motor 42 rotates.

The clutch 84 includes a clutch outer 86, rollers 88 and a clutch inner 90. The clutch inner 90 is engaged with the second ring gear 72. The clutch 84 also includes a clutch fork 128 disposed between the clutch outer 86 and the clutch inner 90. The clutch fork 128 has radially outwardly extending shift blocks 148. The paddle 148 is located between the two rollers. The rollers 88 flank a ramp surface provided on the inner surface of the clutch outer 86. Referring to fig. 11-12, under the action of the motor forward/reverse switching knob 132 and the clutch switching plate 130, the different rollers in the clutch 84 limit the rotation of the clutch inner 90 in different motor rotations. Wherein the switch button 132 is shown in the forward rotation position in fig. 11, the clutch switch plate 130 is toggled to rotate counterclockwise about the pivot shaft, thereby rotating the clutch outer 86 with the clutch fork 128 clockwise. A toggle piece 148 protruding from the inner circumferential surface of the clutch outer 86 toggles one of the rollers 88 to move away from the ramp surface on the clutch outer 86, and the fixing and rotation of the second ring gear 72 are achieved only by the rollers 88 at the other position abutting or disengaging from the ramp surface. The switch knob 132 is shown in the reverse position in fig. 12, and the clutch switch plate 130 is toggled to rotate clockwise about the pivot shaft, thereby rotating the clutch outer 86 with the clutch fork 128 counterclockwise. The shifting block 148 extending from the inner circumferential surface of the clutch outer 86 shifts the rollers at the other position away from the slope surface of the clutch outer 86, and the opposite rollers abut against or are disengaged from the slope surface to fix and rotate the second ring gear 72.

When the motor rotates forward, when the transmission device 46 is in a high-speed gear, the clutch inner ring 90 rotates clockwise under the driving of the second ring gear 72 and the first planet carrier 60, because the shifting block 148 separates and blocks the rollers which are close to the slope surface clockwise from the slope surface, the acting rollers can be far away from the slope surface under the driving of the clutch inner ring 90, and the clutch inner ring 90 can rotate relative to the clutch outer ring 86 under the driving of the second ring gear 72. The output shaft 47 is in a high speed state at this time.

When the tool load changes and the transmission device 46 is required to provide low-speed large torque output, the second ring gear 72 is separated from the first planet carrier 60, the second ring gear 72 tends to rotate counterclockwise, the clutch inner ring 90 also tends to rotate counterclockwise under the driving of the second ring gear 72, so that the acting rollers abut against the slope surfaces, and the clutch inner ring 90 and the clutch outer ring 86 are combined into a whole under the action of the rollers and are fixed relative to the housing 41. The second ring gear 72 is relatively locked. The output shaft 47 is in a low speed state at this time.

Similarly, when the motor rotates in the reverse direction, the clutch inner 90 also locks and drives the second ring gear 72 at different working positions under the action of the clutch switching plate 130. Since the clutch 84 is provided between the second ring gear 72 and the housing 41, the problem of gear rattling does not occur in the process of moving the second ring gear 72 between the first position and the second position.

Referring to fig. 13-18, there is shown a schematic diagram of a control unit with portions of its elements moving from a high gear position to a low gear position. In fig. 13, hook slider 110, hook pin 92 and shift pin 104 move a certain distance by switch block 96, and shift pin arm 118 contacts protrusion 114 on shift block 74 and pulls shift block 74 to move, and at this time, second ring gear 72 is in the high-speed low-torque position. When the electric drill 40 needs to increase the torque to complete a task, due to the increase of the torque, the first internal gear ring 62 overcomes the acting force of the spring 80 and rotates in the reduction gearbox housing 102 relative to the reset plate 82, and the torque value required for rotating the first internal gear ring 62 is determined by the spring 80. After the first ring gear 62 is angularly rotated (as shown in fig. 14), the pin 104 is angularly offset about the axis defined by the slide post 104 such that the pin stop arm 118 is angularly offset from the protrusion 114 on the shift slide 74. When the shift arm 118 and the protrusion 114 are in the position shown in FIG. 15, the shift slider 74 can be moved in a direction away from the hook slider 110. When the shift slider 74 is moved to the position shown in fig. 16, the second ring gear 72 is disengaged from the first carrier 60 and the transmission 46 outputs a low speed high torque. The operator releases the switch 50 and the hook slide 110, hook pin 92 and stop 112 move from a position away from the drill head in a direction closer to the head, losing the force of the switch spring 100, and the hook slide 110, hook pin 92 and stop 112 and the deadbolt 104 move as a whole towards the shift slide 74 to the position shown in fig. 17. After the motor is stopped, due to the small input torque, the first ring gear 62 rotates a certain angle under the action of the spring 80, the cam groove 122 on the first ring gear 62 and the cam surface 120 on the reset plate 82 are attached again, as shown in fig. 18, the first ring gear 62 returns to the same angular position as shown in fig. 13, and correspondingly, the shift pin 104 is driven to deflect, so that the shift pin blocking arm 118 and the protrusion 114 are hooked with each other. At this point, the drawbar slide 110, the deadbolt and the drawbar pin 92 have moved a certain distance towards the working head relative to the position shown in fig. 13, and the transmission 46 has returned from the high gear to the low gear.

Referring to fig. 19 to 27, another embodiment of the power tool with a transmission is shown. The transmission 246 includes a first transmission portion 254, a second transmission portion 264 and a third transmission portion 234. The first transmission portion 254 includes the first center gear 56 sleeved on the armature shaft 43, the first planetary gear 58 engaged with the first center gear 56, the first ring gear 262 engaged with the first planetary gear 58, and the first carrier 60. The second transmission part 264 includes the second sun gear 66, the second planetary gears 68, the second ring gear 72, and the second carrier 70. The third gear portion 234 is connected to the second gear portion 264 and includes the third center wheel 136, the third planet wheel 138, the third ring gear 142, and the third planet carrier 140.

The first ring gear 262 has a ring-shaped main body 178. The annular body 178 is provided with internal teeth 179 on its inner circumference which engage the first planet 58, and with an M-shaped recess 186 and an arcuate slot 188 on its outer circumference. Arcuate slot 188 has two end faces 190. The middle of the front face of the M-shaped recess 186 projects inwardly to form a ledge formed by a top edge and two side edges. Two rotation holes 187 are provided in the projection. The rotation block 184 is received in the rotation hole 187 and rotates within the protruding portion of the M-shaped recess 186 with respect to the axis defined by the rotation hole 187. The compression spring 192 is accommodated in the arc-shaped groove 188, and two ends of the compression spring 192 respectively abut against two end faces 190 of the arc-shaped groove 188. An end face groove 194 is provided on an end face of the first ring gear 262. The T-shaped pin 196 is disposed between the reduction gear housing 102 and the first ring gear 62, and includes a pin portion that can be partially received in the end surface recess 194 and a connecting rod portion disposed perpendicular to the pin portion. A positioning spring 198 is provided between the T-pin 196 and the reduction gearbox housing 102.

The turning block 184 has a turning axis 185 and a substantially trapezoidal main body portion 200. The rotating shaft 185 is received in the rotating hole 187, and the inclined edge of the main body 200 abuts against the side edge of the protruding portion when the main body 200 is connected to the first ring gear 62. The main body portion 200 of the turning block 184 and the M-shaped recess 186 together form a slide slot 202 for the movement of the pin 182 in the shift mechanism. The top edge of the projection of the M-shaped groove 186 forms a continuous circumferential runner 204 with the square edge of the rotating block 184, the other square edge of the rotating block 184 forms an axial runner 206 perpendicular to the circumferential runner 204 with the side edge of the M-shaped groove 186, and the oblique edge of the rotating block 184 forms an oblique runner 208 with the side edge of the M-shaped groove 186.

The switching unit includes a shift plate 180 having a semi-cylindrical main body and a shift wire 76. The shift plate 180 has a receiving groove formed on an outer surface thereof for receiving the shift wire 76 and includes a through hole for receiving the pin 182. The pin 182 is received in a slot 202 formed by the M-shaped recess 186 and the rotating block 184 after passing through the through hole of the shift plate 180. The shift plate 180 is provided with a projection that hooks the shift return spring 78 together with a projection provided on the reduction case housing 102. A slide groove 202 is formed on the periphery of the first ring gear 262, a pin 182 is movably disposed in the slide groove 202, and a shift plate 180 is coupled to the pin 182 and is connected to the reduction gear housing 102 by a shift return spring 78. Under the action of the pulling force of the gear shifting return spring 78, the gear shifting plate 180 moves axially, so that the gear shifting steel wire 76 and the second inner gear ring 72 are driven to move axially to change the meshing relation with the first planet carrier 60, and the rotation speed and the output torque of the working head are automatically adjusted.

The first internal gear 262 is reset under the action of the pressure spring 192. The arc-shaped groove arranged on the outer circumferential surface of the first inner gear ring 262 and the inner arc-shaped groove arranged on the motor housing 101 form a containing space for containing the pressure spring 192, and two ends of the pressure spring 192 respectively abut against the end surfaces 190 on two sides of the arc-shaped groove 188, so that the first inner gear ring 262 can automatically reset.

When the first ring gear 262 is in the position shown in fig. 22 under the action of the compression spring 192, the first ring gear 262 does not rotate relative to the shift pin 182, the pin 182 is in the circumferential slide groove in the slide groove 202 of the first ring gear 262, and when the pin 182 abuts against one top surface of the M-shaped groove and is kept stable against the tension of the shift return spring 78, the second ring gear 72 is in a state of being simultaneously engaged with the first planet carrier 60 and the second planet gears 68, and the transmission 246 outputs high-speed low-torque, in combination with fig. 25.

When the load is changed, the first ring gear 262 rotates in the direction of the arrow E against the torsion of the compression spring 192, but the rotation is limited to a certain range. That is, when the loading torque force does not exceed the predetermined force of the compression spring 192, the pin 182 is retained in the circumferential sliding groove 204 of the first ring gear 262, and the transmission is stabilized in a high-speed output state. However, when the load torsion exceeds the predetermined force of the compression spring 192, the first ring gear 262 rotates by a certain angle against the elastic force of the compression spring 192, and is thus in the position shown in fig. 23. Referring to fig. 22, the pin 182 is now moved from the circumferential slot of the first ring gear 262 to the axial slot of the first ring gear 262 by the shift return spring 78 across the support surface defined by the turning blocks. Due to the movement of pin 182, shift plate 180 and shift wire 76 move axially along the armature shaft, thereby moving second ring gear 72 to a position disengaged from first carrier 60 but engaged with second planet gears 68, and transmission 246 is in a low speed output state. Referring to fig. 20, the pin portion of the T-shaped pin 196 is axially moved by the positioning spring 198 and partially received in the end surface recess 194 due to the rotation of the first ring gear 262, so that the transmission 246 can be stably maintained in a low-speed output state.

Referring to fig. 27, after the motor 42 is stopped, the operator releases the switch trigger 98 and a projection 197 associated with the switch trigger 98 moves the T-pin out of the face recess 194 under the influence of the switch spring against the resilient force of the positioning spring. The compression spring 192 drives the first ring gear 262 to rotate in the direction of arrow F, the pin 182 overcomes the force of the shift return spring 78 and moves along the inclined slide groove 208 of the first ring gear 262, and simultaneously the turning block 184 is turned around the turning shaft 185 until the turning block 184 returns to the position where the inclined surface of the turning block abuts against the inclined edge of the M-shaped groove after the pin 182 moves into the axial slide groove 206. Thus, the first ring gear 262 is returned from the low gear position to the high gear position.

In this embodiment, the first elastic element is a compression spring 192 disposed between the first inner ring gear 262 and the housing. The first ring gear 262 rotates against the elastic force of the first elastic member when the motor load increases and exceeds a preset value. And after the load is reduced, the first elastic element drives the first inner gear ring to return to the initial position. The first elastic element may also be another elastic element, such as a tension spring, a leaf spring or another elastic body, etc., as will be appreciated by those skilled in the art.

In this embodiment, the second resilient member is a tension spring, namely, a shift return spring 78. The second elastic element pulls the shift plates and the pins along the slide slots in first ring gear 262, and in particular along axial slide slots 206 in first ring gear 262, thereby moving second ring gear 72 between the first and second positions to effect a change in transmission output. The output shaft of the electric tool can output proper torque and rotating speed under different working conditions. The second elastic element may also be an elastic element in other forms, such as a compression spring, as will be appreciated by those skilled in the art.

While only a few embodiments of the present inventions have been described and illustrated herein, those skilled in the art will readily envision other means or structures for performing the functions and/or obtaining the structures described herein, and each of such variations or modifications is deemed to be within the scope of the present inventions.

Claims

1. A power tool, comprising:

a housing;

the motor is arranged in the shell and provides rotary power;

the first transmission part is connected with the motor, receives input torque output by the motor, and comprises a first planet carrier and a first inner gear ring with a chute;

the second transmission part is connected with the first transmission part and comprises a second inner gear ring;

the clutch is arranged between the second transmission part and the shell, and the second inner gear ring is limited to rotate when the input torque is larger than a preset value; and

the output shaft is connected with the second transmission part;

it is characterized in that the preparation method is characterized in that,

the electric tool further comprises a first elastic element arranged between the machine shell and the first inner gear ring, a second elastic element arranged between the machine shell and the second inner gear ring, and a speed regulating element partially accommodated in the chute, wherein when the input torque is greater than a preset value, the first inner gear ring rotates against the acting force of the first elastic element, so that the speed regulating element moves in the chute along the axial direction of the first inner gear ring under the action of the second elastic element, the second inner gear ring is driven to move from a first position, which is simultaneously meshed with the second planet wheels and the first planet carrier, to a second position, which is meshed with the second planet wheels and is disengaged from the first planet carrier, and the output shaft outputs different rotating speeds.

2. The power tool of claim 1, wherein: the electric tool comprises a forward and reverse rotation switching button for controlling the rotation direction of the motor, and a clutch switching plate is arranged between the clutch and the forward and reverse rotation switching button to enable the clutch to act in a single direction.

3. The power tool of claim 1, wherein: the clutch comprises an outer ring connected with the shell, an inner ring connected with the second inner gear ring and a rolling body arranged between the outer ring and the inner ring.

4. The power tool of claim 1, wherein: the first inner gear ring is provided with an annular main body, the outer circumferential surface of the annular main body is provided with a sliding groove, and the sliding groove comprises a continuous path formed by a circumferential groove, an axial groove and an inclined groove.

5. The power tool of claim 4, wherein: the rotary block is arranged in the sliding groove and provided with a main body which is basically triangular or right trapezoid, and a circumferential groove, an axial groove and an inclined groove are formed by the side edge of the main body and the inner wall of the sliding groove.

6. The power tool of claim 1, wherein: the first inner gear ring is provided with an annular groove, and the first elastic element is accommodated in the annular groove to resist the rotation of the first inner gear ring.

7. The power tool of claim 6, wherein: the first elastic element is a compression spring.

8. The power tool of claim 1, wherein: the end face of the first inner gear ring is provided with an axial end face groove, the housing is provided with an accommodating hole for accommodating a positioning spring and a positioning pin, and after the input torque exceeds a preset value, the positioning pin is combined with the end face groove under the action of the positioning spring and the first inner gear ring, so that the second inner gear ring is stably kept at the second position.

9. The power tool of claim 8, wherein: the electric tool comprises a switch, the switch is provided with a motor switch, a switch trigger and a switch shifting block, and before the switch trigger triggers the motor switch, the switch shifting block shifts the positioning pin to be disengaged from the end face groove, so that the second inner gear ring is stably kept at the first position.

10. The power tool of claim 1, wherein: the speed regulating element is a pin, the gear shifting plate is sleeved outside the second inner gear ring, the gear shifting steel wire is connected between the gear shifting plate and the second inner gear ring, and the pin penetrates through the rear part of the gear shifting plate and is accommodated in a sliding groove in the first inner gear ring.