CN110594316A - Clutch mechanism for adjusting eccentricity in electric tool - Google Patents

Abstract

A clutch mechanism for adjusting eccentricity in a power tool includes an outer race radially mounted on an annular body mounted on an eccentric shaft. At least one first connecting member is disposed between the outer race and the annular body. At least one second connecting member is arranged between the ring-shaped body and the eccentric shaft. The first connecting member rotates the outer race and the annular body relative to each other in a manner. The second connecting member rotates the ring-shaped body and the eccentric shaft relative to each other in a manner. The annular body has an axial projection formed thereon for connection with an eccentric mechanism in a power plant. A tool. With this clutch mechanism, the adjusted eccentricity will not change during operation, and torque can be transmitted stably.

Description

Clutch mechanism for adjusting eccentricity in electric tool

Technical Field

The invention relates to the technical field of clutch mechanisms for power tools, in particular to a clutch mechanism for a power tool.

Background

EP- ｃA-820838 discloses ｃA clutch mechanism for use in ｃA power tool to adjust eccentricity. The clutch mechanism is used for connecting the tool head with the eccentric sleeve. The eccentric sleeve may rotate relative to the eccentric fan wheel. A spring loaded stop member is mounted on the eccentric sleeve. An annular member is fixed to the eccentric fan wheel and has at least two stopping grooves formed thereon. To adjust the eccentricity, the tool head is rotated and the eccentric sleeve is rotated, which causes the spring-loaded stop member to engage different stop recesses on the annular member. Spring-loaded d & content members and pawl recesses of this type are commonly used in the art for transmitting torque. However, when the torque exceeds a certain level.

Disclosure of Invention

In view of the foregoing, it is a primary object of the present invention to provide a novel and improved clutch mechanism for use in a power tool to adjust eccentricity.

It is another object of the present invention to provide a clutch mechanism for adjusting eccentricity used in a power tool, which makes the adjusted eccentricity stable and enables stable power transmission regardless of whether torque is increased or not.

In one embodiment, the present invention provides a clutch mechanism for adjusting eccentricity for use in a power tool. The clutch mechanism may include an outer race, an annular body, an eccentric shaft, at least one first connecting member disposed between the outer race and the annular body, and at least one second connecting member disposed between the annular body and the eccentric shaft. A shaft. The first connecting member makes the outer race and the ring body rotatable relative to each other. The second connecting member makes the ring-shaped body and the eccentric shaft rotatable relative to each other.

In a preferred embodiment, the present invention provides a clutch mechanism for adjusting eccentricity in a power tool, the clutch mechanism comprising: an eccentric shaft drivable by a main drive shaft; an annular body mounted radially on the eccentric shaft. The outer race is radially mounted on the annular body. At least one first connecting member is disposed between the outer race and the annular body such that the outer race and the annular body are rotatable together in the same direction when the main drive shaft is locked. And at least one second connecting member disposed between the ring-shaped body and the eccentric shaft such that the ring-shaped body and the eccentric shaft can rotate together in the same direction when the main driving shaft rotates. An eccentric shaft drivable by a main drive shaft; an annular body mounted radially on the eccentric shaft. The outer race is radially mounted on the annular body. At least one first connecting member is disposed between the outer race and the annular body such that the outer race and the annular body are rotatable together in the same direction when the main drive shaft is locked. And at least one second connecting member disposed between the ring-shaped body and the eccentric shaft such that the ring-shaped body and the eccentric shaft can rotate together in the same direction when the main driving shaft rotates.

The clutch mechanism of the present invention stabilizes the adjusted eccentricity and stably transmits power regardless of an increase in torque. In particular, the clutch mechanism of the present invention allows adjustment of the eccentricity to be maintained while it is in use. Can stably transmit torque and improve working efficiency.

In a preferred embodiment, a first inclined wall is formed between the outer race and the ring-shaped body, and a second inclined wall is formed between the ring-shaped body and the eccentric shaft, wherein the first connecting member is a first roller movable along the first roller. The inclined wall and the second connecting member are a second roller movable along the second inclined wall.

Preferably, the ring-shaped body has an outer peripheral wall and an inner peripheral wall, and wherein the first inclined wall is formed on the outer peripheral wall and the second inclined wall is formed on the inner peripheral wall. Particularly preferably, the inner circumferential wall has a plurality of first frustoconical recesses and the outer circumferential wall has a plurality of second frustoconical recesses, each first frustoconical recess having a wall that serves as a first inclined wall and each second frustoconical recess having a second wall. A wall serving as a second inclined wall. It is particularly preferred that each of the first and second frustoconical recesses terminates in a narrow receiving hole. Preferably, a loaded resilient member is arranged in each narrow receiving hole.

In a preferred embodiment, the annular body has an axial projection formed on the end face, which can cooperate with a corresponding recess on the eccentric mechanism. In a preferred embodiment, the annular body comprises a base having at least one first fixing member and a cover having at least one second fixing member adapted to cooperate with the first fixing member.

In a preferred embodiment, the eccentric shaft has a longitudinal bore for radially and securely mounting the eccentric shaft on the main drive shaft.

Preferably, the annular body has an inner circumferential wall and an outer circumferential wall, wherein the eccentric shaft has an outer wall and a longitudinal bore having a central axis a, wherein the central axes of the outer and inner circumferential walls are Q, and the central axes of the outer and outer circumferential walls are P, wherein the central axes a, P and Q are eccentric.

Preferably, the annular body has an inner peripheral wall with a plurality of first frustoconical recesses and an outer peripheral wall with a plurality of second frustoconical recesses, wherein the second connecting member is located in each first frustoconical recess and is positioned in each second frustoconical recess. The tapered recess is disposed on the first connecting member, wherein each of the first connecting member and the second connecting member is a resilient element connected to the roller, whereby the resilient element urges the roller outward.

Preferably, in use, the rollers in the inner circumferential wall securely engage the main drive shaft as the main drive shaft rotates.

Preferably, in use, as the main drive shaft rotates, the rollers in the peripheral wall disengage the outer race.

Preferably, the rollers in the outer circumferential wall engage the outer race when the main drive shaft is locked in use.

Preferably, in use, when the main drive shaft is locked, the central axis P rotates about the central axis Q, thereby adjusting the eccentric stroke P relative to a.

The first sanding plate may be operably connected or coupled to the eccentric shaft. A coupling member (e.g., a coupling sleeve) may be radially mounted on the eccentric shaft and may carry a first sand plate (e.g., an outer sand plate). The central axis of the coupling member (and thus of the first sand table) is the central axis P. When the main drive shaft of the power tool is locked (e.g., by the chuck), the outer race may rotate, causing the annular main body to rotate with the outer race to rotate the central axis P about the central axis Q to adjust the eccentric stroke of the first sanding disc (i.e., the eccentric stroke of P relative to a).

The eccentric mechanism of the power tool may be mounted on the main drive shaft. An axial protrusion may be formed on one face of the cap for connecting the annular body to an eccentric mechanism of the power tool. The eccentric mechanism may comprise a second eccentric shaft which is radially fixedly mounted on the main drive shaft. A coupling member (e.g. a coupling sleeve) may be radially mounted on the second eccentric shaft and may carry a second grinding plate (e.g. an inner grinding plate). The centre axis T (and thus the second sand plate) and the centre axis P of the coupling member may be symmetrically distributed around the centre axis a. When the main drive shaft of the power tool is locked (e.g. by a chuck),

in one embodiment, a first eccentric member is radially mounted on the main drive shaft, the first eccentric member having a first central axis. A second eccentric member is radially mounted on the main drive shaft, the second eccentric member having a second central axis. The mechanism further includes a coupling member for coupling the first eccentric member to the second eccentric member, wherein the eccentricity of the first central axis and the eccentricity of the second central axis relative to the central axis of the main drive shaft are adjustable.

In a preferred embodiment, the first eccentric has a first eccentric sleeve, the second eccentric has a second eccentric sleeve, and the first and second eccentric sleeves are rotatable relative to the main drive shaft, wherein a center axis of the first eccentric sleeve is a first center axis of the first eccentric member and a center axis of the second eccentric sleeve is a second center axis of the second eccentric member.

Particularly preferably, the first eccentric member has a first eccentric shaft, the second eccentric member has a second eccentric shaft, and the first eccentric shaft and the second eccentric shaft are radially fixedly mounted on the main drive shaft, wherein the first eccentric sleeve and the second eccentric sleeve are rotatably mounted on the first eccentric shaft and the second eccentric shaft, respectively, wherein a center axis of the first eccentric shaft and a center axis of the second eccentric shaft are eccentric with respect to a center axis of the main drive shaft, wherein a center axis of the first eccentric sleeve is eccentric with respect to a center axis of the first eccentric shaft and a center axis of the main drive shaft, and wherein a second eccentricity of the eccentric shaft in which a center axis of the second eccentric sleeve is eccentric with respect to the center axis corresponds to the center axis of the main drive shaft.

The second grinding wheel plate may be operatively connected or coupled to the second eccentric sleeve such that, in practice, the central axis of the second eccentric sleeve is the central axis of the second eccentric member and the second grinding wheel plate.

Preferably, the central axis of the first eccentric sleeve and the central axis of the second eccentric sleeve are on opposite sides of the central axis of the main drive shaft. The central axis of the first eccentric sleeve and the central axis of the second eccentric sleeve may be parallel to the central axis of the main drive shaft. The central axis of the first eccentric sleeve, the central axis of the second eccentric sleeve and the central axis of the main driving shaft may be on the same plane. The central axis of the first eccentric bushing and the central axis of the second eccentric bushing may be equidistant from the central axis of the main drive shaft.

Preferably, the central axis of the first eccentric shaft and the central axis of the second eccentric shaft are on opposite sides of the central axis of the main drive shaft. The central axis of the first eccentric shaft and the central axis of the second eccentric shaft may be parallel to the central axis of the main drive shaft. The central axis of the first eccentric shaft, the central axis of the second eccentric shaft and the central axis of the main drive shaft may be in the same plane. The central axis of the first eccentric shaft and the central axis of the second eccentric shaft may be equidistant from the central axis of the main drive shaft.

The first and second eccentric sleeves may be generally cylindrical and may terminate in a radial collar.

The bearing may be mounted radially tightly on the second eccentric sleeve. The bearing seats may be mounted around the circumference of the bearing. The sanding plate may be secured to a bearing block.

Preferably, the coupling member is fixedly mounted on the first eccentric shaft and has a first pin on an upper surface and a second pin on a lower surface, wherein each of the first and second eccentric sleeves has a radial slot for receiving the first eccentric sleeve. A pin and a second pin, wherein the width of the slot approximates the diameter of the pin. In order to mount the coupling member on the first eccentric shaft, the first eccentric shaft may include an annular protrusion on a lower surface thereof.

Preferably, the coupling member has an operating body rotatably mounted on the main drive shaft and an extension pin axially extending from the operating body, wherein each of the first and second eccentric sleeves has a receiving hole for receiving the extension pin, wherein a diameter of the receiving hole is similar to a diameter of the extension pin, and a length of the receiving hole is greater than a length of the extension pin.

Preferably, a plurality of positioning sockets are formed on outer surfaces of the first and second eccentric shafts, and a plurality of receiving recesses are formed on inner circumferential surfaces of the first and second eccentric sleeves, wherein each receiving recess is seated on an elastic member (e.g., a spring) connected to a positioning post, wherein each positioning post is selectively received in the positioning socket to captively couple the first and second eccentric sleeves with the first and second eccentric sleeves. A shaft.

The first grinding plate may be connected or coupled to the first eccentric member. The second sanding plate may be connected or coupled to the second eccentric member. The first sanding plate and the second sanding plate may terminate at the bottom of the housing. The first coated abrasive and the second coated abrasive may be an exterior coated abrasive and an interior coated abrasive. The or each abrasive plate may be annular (e.g. stepped annular).

Preferably, the clutch mechanism further comprises a principle drive shaft locking means. It is particularly preferred that the main drive shaft locking device comprises:

a chuck mounted radially on the main drive shaft, wherein the chuck has a skirt extending axially downward from a circumferential edge thereof, wherein a plurality of notches are provided around the skirt; and

a locking member is attached to the housing, wherein the locking member is selectively insertable into the groove to lock the chuck and prevent rotation of the main drive shaft. More preferably, the clutch mechanism further includes: a balance drum, wherein the chuck has a central hole surrounded by the eccentric hub, and the balance drum is fixedly mounted on the eccentric hub.

A chuck mounted radially on the main drive shaft, wherein the chuck has a skirt extending axially downward from a circumferential edge thereof, wherein a plurality of notches are provided around the skirt; and

a locking member is attached to the housing, wherein the locking member is selectively insertable into the groove to lock the chuck and prevent rotation of the main drive shaft. More preferably, the clutch mechanism further includes: a balance drum, wherein the chuck has a central hole surrounded by the eccentric hub, and the balance drum is fixedly mounted on the eccentric hub.

A plurality of spaced apart locating holes may be formed around the eccentric hub. The balancing drum may include a central bore defined by the hub.

The annular body may abut an end face of a balancing drum (e.g., hub). The balancing drum may have partial radial grooves extending from the hub. A spring and a ball locating post connected to the spring may be disposed in the recess. The ball positioning post can be partially pushed into a positioning hole on the eccentric hub to connect the balance drum and the chuck in a restraining manner.

The annular body may abut an end face of the chuck (e.g., an eccentric hub). The annular body may have a radial groove. A spring and a ball locating post connected to the spring may be disposed in the recess. The ball stud can be pushed partially into the locating hole on the eccentric hub to restrain the clutch and chuck.

The sanding disc may be radially mounted on the outer race. The support bearing may be radially mounted on the first eccentric sleeve. The support bearing may be substantially axially aligned with the outer race. The disc may be mounted radially on the outer race and the bearing.

Drawings

Fig. 1 is a cross-sectional view of a sander of a first embodiment of the present invention;

fig. 2 is a partially exploded view of the sander of fig. 1;

FIG. 3 is a cross-sectional view taken along line MM shown in FIG. 2;

FIG. 4 is an exploded perspective view of the eccentric stroke adjustment mechanism shown in FIG. 3;

FIG. 5 is a front plan view of FIG. 4;

fig. 6 is a cross-sectional view of a sander of a second embodiment of the present invention;

fig. 7 is a cross-sectional view of a sander of a third embodiment of the present invention;

fig. 8 is a cross-sectional view in another direction of a sander according to a third embodiment of the present invention;

FIG. 9 is a sectional view taken along the NN line shown in FIG. 8;

FIG. 10 is an exploded perspective view of one embodiment of the clutch mechanism of the present invention;

FIG. 11 is a longitudinal cross-sectional view of the clutch mechanism of FIG. 10;

fig. 12 is an axial cross-sectional view of the clutch mechanism of fig. 11.

Detailed Description

It will be readily understood that the components of the present invention, as generally described herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the present invention, as disclosed in the figures included herein, is not intended to limit the scope of the invention, as claimed, but is merely representative of presently preferred embodiments of the invention.

Referring to fig. 1, a first embodiment of the present invention is a rotary sander. The sander generally comprises a housing 1, a motor 2 vertically disposed within the housing 1, a main drive shaft 3, a sanding plate 4 at the bottom of the housing, and an eccentric stroke adjustment mechanism 5.

Referring to fig. 2 to 5, the housing 1 comprises an upper housing part 12 and a lower housing part 14 which are firmly connected to each other. The fan 16 is firmly mounted on the main drive shaft 3. The main drive shaft 3 includes an armature shaft 30 and a connecting shaft 32 connected to a lower end of the armature shaft 30. The connecting shaft 32 and the armature shaft 30 have a common axis X0. The connecting shaft 32 has an irregular cross section. The lapping plate 4 has an annular inner plate 42 and an annular outer plate 44. The braking system 6 is disposed between the lower housing portion 14 and the annular outer plate 44.

The eccentric stroke adjusting mechanism 5 includes a principle drive shaft locking device 8, a first eccentric member 56, a second eccentric member 58, and a coupling member 77 for coupling the first eccentric member 56 and the second eccentric member 58. The first eccentric member 56, the coupling member 77 and the second eccentric member 58 are mounted radially downward on the connecting shaft 32 in this order.

The principle driving shaft locking device 8 includes a chuck 52 and a bolt member 50 radially installed on an upper portion of the connecting shaft 32. The chuck 52 has a skirt 520 extending axially downwardly from its periphery. A plurality of grooves 524 are distributed around skirt 520. The bolt members 50 are attached to the lower housing portion 14 and can be selectively inserted into corresponding recesses 524 to lock the chuck in adjusting the eccentric travel of the sanding disc 4 (as described below), which is shown in FIG. 1. Chuck 52 has a generally central bore 51 surrounded by an eccentric hub 53. A plurality of spaced locating holes 525 are formed in the eccentric hub 53.

A balancing drum 55 is mounted on the eccentric hub 53 to cooperate with the annular inner plate 42 to balance the weight of the annular outer plate 44. The balance drum 55 includes a central bore 57 and a hub engagement 57. The balance drum 55 has a partial radial groove 59 extending from the hub 57. A spring 590 and a ball locating post 592590 connected to the spring are disposed in the recess 59. Ball positioning posts 592 extend partially into positioning holes 525 under the force of springs 590 to captively couple balance drum 55 and chuck 52.

The rotary sander of the first embodiment of the present invention further includes an overrunning clutch 54. The overrunning clutch 54 is a one-way rotation clutch having a self-locking function. The overrunning clutch 54 has an annular main body 60 that abuts against an end surface of the hub 57. An outer race 64 is radially mounted on the annular body 60 between the overrunning clutch 54 and the annular outer plate 44. A locking ring 594 is axially interposed between the outer race 64. A balancing drum 55. The ring-shaped body 60 has an inner peripheral surface on which three first frustoconical recesses 662 are formed and an outer peripheral surface on which three second frustoconical recesses 66 are formed. At the bottom of each of the first and second frustoconical recesses 662, 66 is a narrow receiving hole 61. A loaded spring 68 is disposed in each narrow receiving hole 61 and is connected to the rollers 63, respectively. Seated in the conical recesses 66, 662. The loaded spring 68 pushes the roller 63 away from the narrow receiving hole 61. An axial projection 602 extends from the lower surface of the annular body 60 adjacent the inner peripheral surface.

The first eccentric member 56 is radially mounted on the main drive shaft 3. The first eccentric member 56 includes a first eccentric shaft 62, the first eccentric shaft 62 having a first hole 65 formed along an axis parallel to the central axis X3 thereof. The shape of the first hole 65 matches the shape of the connecting shaft 32 so that the first eccentric shaft 62 can be firmly radially mounted on the connecting shaft 32. The central axis X3 is eccentric with respect to the central axis X0. The overrunning clutch 54 is mounted on the upper end of the first eccentric shaft 62 in the radial direction. The first eccentric member 56 further includes a first eccentric sleeve 69 rotatably mounted on the lower end of the first eccentric shaft 62. The first eccentric bushing 69 has a central axis X1 and an eccentricity of the central axis X1 with respect to the central axis X0 of the main drive shaft 3. Is adjustable. The central axis X1 is eccentric with respect to the central axis X3.

The support bearing 71 is tightly mounted on the first eccentric sleeve 69 and has its outer surface substantially aligned with the outer surface of the outer race 64. The annular outer plate 44 is in close engagement with the outer surface of the outer race 64 and the support bearing 71. The center axis 44 of the annular outer plate coincides with the center axis X1 with the center axis X1 of the first eccentric sleeve 69 and the like, which practically defines the entirety of the center axis of the first eccentric member 56. A washer 70 is axially disposed between the annular body 60 and the support bearing 71. The end of the first eccentric sleeve 69 abuts the lower surface of the washer 70 and has a recess 622 at its upper end to receive the protrusion 602 so that the first eccentric sleeve 69 is securely connected to the overrunning clutch 54. The first eccentric shaft 62 has a plurality of holes 67 extending parallel to its central axis X3 to reduce its weight.

The second eccentric member 58 is formed substantially symmetrically to the first eccentric member 56 with respect to the main drive shaft 3. The second eccentric member 58 comprises a second eccentric shaft 73 fixedly mounted on said second eccentric shaft 73 radially on the connecting shaft 322 and a second eccentric sleeve 75 rotatably mounted on said second eccentric shaft 73. Central axis X4 the central axes of the second eccentric shaft 73 and the central axis X3 the first eccentric shaft 62 are symmetrically distributed around the central axis X0. The central axis X2 and the second eccentric sleeve 75 and the first eccentric sleeve 69 of the central axis X1 are symmetrically distributed 0 about the central axis X. The central axis X2 defines, in operation, the central axis of the entire second eccentric member 58.

The coupling member 77 is mounted on an annular protrusion 624 formed on the bottom surface of the first eccentric shaft 62. The coupling member 77 has first and second pins 79 and 79 formed on top and bottom surfaces thereof, respectively. The first and second pins 79 and 79 are symmetrically distributed with respect to the central axis of the coupling member 77. The first eccentric sleeve 69 and the second eccentric sleeve 75 each have a radial slot 80 to receive a respective pin.

The bearing 71 is radially tightly fitted on the second eccentric sleeve 75. Bearing mount 82 is mounted around the periphery of bearing 71. A plurality of bolts fasten the inner annular plate 42 to the bearing housing 82. The inner annular plate 42 and the second eccentric sleeve 75 are coaxial. A guard 91 is mounted on the bottom end of the coupling shaft 32 to hold the second eccentric member 58 and the bolt 93.

Tightly fixed thereon when the eccentric stroke of the grinding plate 4 is to be adjusted, the bolt member 50 is inserted into the corresponding recess 524 of the chuck 52 to prevent the main drive shaft 3 from rotating. The annular outer plate 44 rotates in the direction indicated by the arrow a in fig. 1. The outer race 64 rotates together with the annular outer plate 44. Friction between the outer race 64 and the rollers 63 of the overrunning clutch the first eccentric sleeve 69, the second eccentric sleeve 75 and the inner annular plate 42 in fig. 1 rotate accordingly. By virtue of the fact that the annular outer plate 44 is firmly coupled to and coaxial with said first eccentric sleeve 69, 44 of the annular outer plates of the central axis X1 rotate 3 about the central axis X said first eccentric shaft 62. Since the center axis X0 of the main drive shaft 3 is fixed by θ 1, the distance between the center axes X1 and X0 (i.e., the eccentric stroke of the annular outer plate 44) changes. The eccentric stroke of the central axis X2 of the annular inner plate 42 with respect to the central axis X0 also changes and approaches the eccentric stroke of the annular outer plate 44. The overdrive clutch 54, spring 590 and ball positioning post 59252 disposed between the balance drum 55 and the chuck prevent displacement of the adjusted eccentric stroke. The eccentric stroke adjustment mechanism 5 can adjust the eccentric strokes 42, 44 of more than one sanding plate as required by the workpiece while ensuring that the sander is balanced during operation.

Fig. 6 shows a rotary sander of a second embodiment of the present invention. Parts of the second embodiment that are the same as or similar to parts of the first embodiment will not be described in detail and will be given the same reference numerals. The rotary sander of the second embodiment includes an upper housing portion 12, a lower housing portion 14, a motor 2 disposed vertically inside the housing 1, a main drive shaft 3, a sanding disc 4, and an eccentric stroke adjustment mechanism 5. The eccentric stroke adjusting mechanism 5 includes an overrunning clutch 54, a first eccentric member 56, and a second eccentric member 58. A coupling member 77 couples the first eccentric member 56 and the second eccentric member 58. The grinding disc 4 of the second embodiment is a single disc. The weight 9 is directly attached to the second eccentric sleeve 75 of the second eccentric member 58 (instead of the annular inner plate 44). And the bearing of the first embodiment). In the second embodiment, the balance drum 55 is not present. Instead, the overrunning clutch 54 directly engages the chuck 52 and there is a groove 59 on the upper surface of the annular body 60 of the overrunning clutch 54. Spring 590 and ball stud 592 are attached to spring 590 and are disposed in recess 59. Ball locating posts 592 extend partially into locating holes 525 and are captively coupled to overrunning clutch 54 and chuck 52 under the force of spring 590.

Fig. 7 to 9 show an eccentric stroke adjusting mechanism 5 'of a third embodiment of the present invention (similar to the eccentric stroke adjusting mechanism 5 of the first and second embodiments described above) which is used in a power tool having a main drive shaft 3'. The eccentric stroke adjusting mechanism 5 'includes a first eccentric member 56' mounted to the principle drive shaft 3', and a second eccentric member 58' mounted to a coupling member 77 'of the principle drive shaft 3 and a coupling member 77' coupling the first eccentric member 56 'and the second coupling member 58'.

The first eccentric member 56 'has a first center axis X1'. The second eccentric member 58 'has a second center axis X2'. The eccentric stroke of the first central axis X1 'and the second central axis X2' with respect to the central axis X0 'of the main drive shaft 3' is adjustable. The first eccentric member 56' comprises a first eccentric shaft 62' and a first eccentric sleeve 69 mounted radially on the main drive shaft 3 '. Rotatable with respect to the main drive shaft 3'. The second eccentric member 58' comprises a second eccentric shaft 73' mounted on the main drive shaft 3' and a second eccentric sleeve 75' rotatable relative to the main drive shaft 3 '. The first eccentric shaft 62 of the central axis X3' and the second eccentric shaft 73' of the central axis X '4' are eccentric with respect to the central axis X0 in principle driving the shaft 3' and its opposite side. The first and second eccentric sleeves 69 'and 75' are rotatably mounted on the first and second eccentric shafts 62 'and 73', respectively. The central axis 69' of the first eccentric sleeve is practically defined as the central axis X1' of the first eccentric part 56 '. The central axis 75 'of the second eccentric sleeve is in practice defined as 58 "of the second eccentric part of the central axis X2'. The first eccentric sleeve 69 'of the central axis X1' is 3 'of the principal drive shaft of the first eccentric shaft 62 and the central axis X'0 'eccentric with respect to the central axis X3'. The second eccentric sleeve 75' of the central shaft X2' is eccentric with respect to the second eccentric shaft 73 of the central shaft X4' and "the central axis X '3' of the principal drive shaft". The central axes X1X ' and X2' are on opposite sides of the central axis X0 '.

A plurality of positioning grooves 83 are formed on the outer surfaces of the first and second eccentric shafts 62 'and 73'. A plurality of radial receiving recesses 85 are formed on inner circumferential surfaces of the first and second eccentric sleeves 69 'and 75'. Each accommodation recess 85 has a resilient member 87 seated therein, and a positioning post 89 is connected to the resilient member 87. The positioning posts 89 and the eccentric sleeves 60' are selectively receivable in corresponding ones of the positioning sockets 83 to constrain the first and second eccentric sleeves 69' and 75' and the first and second eccentric shafts 62' and 73', respectively.

The coupling member 77 'has an operating body 84 rotatably mounted on the main drive shaft 3' and an extension pin 86 extending downwardly therefrom. Each of the first and second eccentric sleeves 69', 75' has an axial receiving hole 88 to receive the extension pin 86. The diameter of the receiving bore 88 is similar to the diameter of the extended pin 86. The length of the receiving hole 88 is longer than the length of the extension pin 86.

The sand discs 46 and 48 are coupled to the first and second eccentric sleeves 69 'and 75' by bearings 90. A sealing ring 92 is interposed between the grinding disc 46 and the first eccentric sleeve 69'.

The operating body 84 of the coupling member 77' may be manually rotated to allow the eccentric stroke of the sandboards 46 and 48 to be adjusted. The adjustment principle is the same as described above for the first and second embodiments.

Fig. 10-12 illustrate an embodiment of the clutch mechanism 100 of the present invention alone for adjusting eccentricity in a power tool. The clutch mechanism 100 comprises an annular body 2 mounted radially on the upper part of an eccentric shaft 3. The annular body 2 comprises a base 2 and a cover 2. the base 2 has an outer peripheral wall 21, an inner peripheral wall 22 having a central axis Q, a top surface 23 and a bottom surface. The axis and the axis Q of the outer peripheral wall 21 are eccentric with respect to each other. The base 2 has a space 23 on the top surface with three axial locating pins 231. The cover 2b has three positioning holes 25 formed at regular intervals. Three pins 231 are engaged with the three holes 25, respectively. Formed on one face 2b of the cover is an axial projection as shown in fig. 12 for connecting the clutch mechanism 100 to an eccentric mechanism (not shown) of the power tool.

The annular outer ring 1 has an outer wall 11 and an inner wall 12 and is mounted radially on the annular body 2. The outer ring 1 has a center axis P21 coinciding with the center axis of the outer peripheral wall. Radially on the outer race 1 is firmly mounted a coupling means, such as a coupling sleeve, for coupling the eccentric shaft 3 to a sand table (not shown). The central axis of the coupling device (and thus also of the abrasive disc) coincides with the axis P.

Three first truncated cone-shaped recesses 210 are formed at 120 ° intervals in the outer peripheral wall 21 of the annular body 2. Each first frustoconical recess 210 has an inclined wall 212 and a retaining wall 213. Each first frustoconical recess 210 terminates in a narrow receiving hole 211. The loaded spring 41 is arranged in a narrow receiving hole 211 and is connected to the outer roller 42 seated in the truncated cone shaped recess 210.

Three second truncated cone shaped recesses 220 are formed at 120 ° intervals on the inner circumferential wall 22 of the ring-shaped body 2. Each second frusto-conical recess 220 has an inclined wall 222 and a retaining wall 223. Each second truncated cone shaped recess 220 terminates in a narrow receiving hole 221. The loaded spring 51 is disposed in a narrow receiving hole 221 and is connected to the inner roller 52 fixed in the truncated cone shaped recess 220.

The eccentric shaft 3 has three longitudinal off-axis bores 30 to reduce its weight and improve its balance. The eccentric shaft 3 has an outer wall 31 and a longitudinal hole 32 formed parallel to its central axis. The shape of the longitudinal bore 32 matches the shape of the main drive shaft of the power tool (not shown) so that the eccentric shaft 3 can be mounted radially firmly on the main drive shaft. The longitudinal bore 32 has a linear portion 33 for engaging a linear portion of the main drive shaft. The central axis of the outer wall 31 is the same as the central axis Q of the inner circumferential wall 22. The longitudinal bore 32 has a central axis a. The central axes a, Q and P are eccentric with respect to each other.

To assemble the clutch mechanism 100, the cover 2b is mounted to the base 2 by inserting the three pins 231 into the three holes 25. Next, the ring-shaped body 2 is radially mounted on the upper portion of the eccentric shaft 3. Each inner roller 52 is arranged between the inclined wall 222 of the second frusto-conical recess 220 and the outer wall 31 of the eccentric shaft 3. . Finally, the outer race 1 is radially mounted on the annular body 2. Each outer roller 42 is disposed between the first inclined wall 212 of the first frustoconical recess 210 and the inner wall 12 of the outer race 1. The first and second retaining walls 213, 223 prevent the outer and inner rollers 42, 52 from falling out of the first and second frustoconical recesses 210, 220, respectively.

In use, when the eccentric shaft 3 is driven by the main drive shaft of the power tool, the spring 51 urges the inner roller 52 in the engagement direction indicated by arrow c, and the annular body 2 rotates about the axis together with the eccentric shaft 3. A in the direction of arrow a. In this case, the clutch mechanism 100 functions as a power transmission mechanism. In use, when the main drive shaft of the power tool is locked (e.g. by a chuck), the outer race 1 may rotate and the outer roller 42 is urged by the spring. Fig. 4 is a view in the joining direction indicated by arrow b. Friction between the outer roller 42 and the outer ring 1 causes the ring body 2 to rotate together with the outer ring 1. The central axis P rotates about the central axis Q, thereby adjusting the eccentric stroke of the sand table (i.e., P relative to a).

Although the present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (10)

1. A clutch mechanism for adjusting eccentricity in a power tool, comprising: an eccentric shaft drivable by a main drive shaft; an annular body mounted radially on the eccentric shaft, an outer race mounted radially on the annular body; at least one first connecting member is provided between the outer race and the annular body such that the outer race and the annular body are rotatable together in the same direction when the main drive shaft is locked, and at least one second connecting member is provided between the annular body and the eccentric shaft such that the annular body and the eccentric shaft are rotatable together in the same direction when the main drive shaft is rotated.

2. The clutch mechanism according to claim 1, wherein a first inclined wall is formed between the outer race and the annular body, a second inclined wall is formed between the annular body and the eccentric shaft, and the first connecting member is a first roller movable along the first inclined wall and the second connecting member is a second roller movable along the second inclined wall.

3. The clutch mechanism according to claim 2, wherein the annular body has an outer peripheral wall on which the first inclined wall is formed and an inner peripheral wall on which the second inclined wall is formed.

4. The clutch mechanism according to claim 3, wherein the inner circumferential wall has a plurality of first truncated cone-shaped recesses, the outer circumferential wall has a plurality of second truncated cone-shaped recesses, the first truncated cone-shaped recesses have a wall as the first inclined surface, and the wall and each of the second truncated cone-shaped recesses have a wall that serves as a second inclined wall.

5. The clutch mechanism of claim 4, wherein each of the first and second frustoconical recesses terminates in a narrow receiving bore.

6. A clutch mechanism according to claim 5, wherein a loaded resilient member is arranged in each narrow receiving aperture.

7. A clutch mechanism according to claim 1 or 2, characterized in that the annular body is formed on its end face with an axial projection which cooperates with a corresponding recess on the eccentric mechanism.

8. The clutch mechanism of claim 1, wherein the annular body comprises: a base having at least one first securing member; and a cover having at least one second securing member adapted to mate with the first securing member.

9. Clutch mechanism according to claim 1, characterized in that the eccentric shaft has a longitudinal bore for firmly mounting the eccentric shaft in a radial direction on the main drive shaft.

10. A clutch mechanism according to claim 1 or 2, characterized in that the ring-shaped body has an inner circumferential wall and an outer circumferential wall, the eccentric shaft has an outer wall and a longitudinal bore with a central axis a, the central axis wall and the inner circumferential wall of the outer shaft are Q, and the central axes of the outer circumferential wall and the outer race are P, wherein the central axes a, P and Q are eccentric.