JP2006205268A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool having an output shaft installing structure for preventing slipping-out of a retaining ring from a groove of an output shaft. <P>SOLUTION: This power tool 1 has a motor, the output shaft 4 for transmitting rotational torque of the motor, a bearing 61 for movably supporting the output shaft 4 in the shaft direction, a carrier 34c for transmitting the rotational torque from the motor to the output shaft 4, a groove part 43 concentrically formed with the output shaft 4 on the output shaft 4, the retaining ring 44 having an abutment part and an annular part, fitted to the groove part 43 by changing an inner diameter of the annular part by changing an interval of the abutment part and preventing separation of the output shaft 4 from the bearing 61 by abutting on the bearing 61, and a regulating means 45a for preventing the expansion of the inner diameter of the annular part in a state of fitting the retaining ring 44 to the groove part 43. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric power tool, and more particularly to an electric power tool having an output shaft mounting structure that prevents a retaining ring from being removed from a groove of an output shaft.

  Conventionally, electric tools have been used for operations such as screw tightening and drilling. FIG. 6 is a cross-sectional view showing an example of the structure of a conventional power tool 100. The electric tool 100 includes a motor (not shown), a motor shaft 200, a speed reduction unit 300, an output shaft 400, and a tool holding unit 500. In the electric power tool 100, the rotation transmitted from the motor to the motor shaft 200 is decelerated by the decelerating unit 300 and output to the output shaft 400. And a desired operation | work can be performed by attaching a desired tool to the tool holding | maintenance part 500 provided in the front-end | tip part of the output shaft 400. FIG.

  The output shaft 400 has a groove portion 401, and a circumferential retaining ring 402 having a joint portion is fitted in the groove portion 401. The output shaft 400 is supported by a bearing 403 and a bearing 404. A washer 405 is disposed between the retaining ring 402 and the bearing 403 to prevent the retaining ring 402 and the bearing 403 from coming into direct contact with each other and being damaged. Further, play is provided so that the output shaft 400 can move slightly in the axial direction so that the output shaft 400 does not come into strong contact with the bearing 403 and a resistance that prevents rotation of the output shaft 400 is not generated.

Usually, when a hole is made in wood, a tool attached to the tool holding unit 500 (in this case, a woodworking cone or the like) is pressed against the wood to perform work. Will be added. However, since the electric power tool 100 is structured to receive this pressing force by the bearing 404, no thrust load is applied to the retaining ring 402 (see, for example, Patent Document 1).
JP-A-4-59112

  However, in the electric power tool 100 of Patent Document 1, when a woodworking cone penetrated after drilling work is pulled out from the wood, the cone is caught on the wood, and the tensile force from the cone is applied to the output shaft 400 via the tool holding unit 500. Will join. At this time, if the groove 401 is not sufficiently processed and has an R shape, the step of the groove 401 is small, or if the corner of the retaining ring 402 is bent during the manufacturing process, the retaining ring 402 In some cases, the output shaft 400 spreads out of the groove 401 and the output shaft 400 comes out of the bearing 403.

  Then, an object of this invention is to provide the electric tool which has an output shaft attachment structure which prevents that a retaining ring remove | deviates from the groove | channel of an output shaft.

  In order to achieve the above object, an electric tool according to claim 1 includes a motor, an output shaft to which rotational torque of the motor is transmitted, and a bearing for supporting the output shaft so as to be movable in an axial direction. A carrier for transmitting rotational torque from the motor to the output shaft, a groove formed concentrically with the output shaft on the output shaft, a joint portion and an annular portion, and the joint portion A retaining ring for changing the inner diameter of the annular portion by changing the interval of the ring portion, fitting the groove portion into the groove portion, and preventing the output shaft from being detached from the bearing by contacting the bearing. The provided electric tool is characterized in that it includes a restricting means for preventing the inner diameter of the annular portion from expanding in a state where the retaining ring is fitted in the groove portion.

  Further, in the electric tool according to claim 2, the restricting means extends in the axial direction of the output shaft, and the annular portion moves in the radial direction so that the outer peripheral surface of the annular portion comes into contact with the power tool. The inner diameter of the annular portion is prevented from expanding.

  According to a third aspect of the present invention, in the power tool according to the third aspect, the restricting means has a substantially cylindrical shape, and the annular portion moves in the radial direction so that the outer peripheral surface of the annular portion contacts the inner diameter portion of the cylinder. The inner diameter of the annular portion is prevented from expanding.

  The power tool according to claim 4, wherein an inner diameter of the restricting means having the substantially cylindrical shape is smaller than a length of a sum of a radius of the output shaft and a radial width of the annular portion, and the output shaft It is characterized by being larger than the total length of the radius of the groove portion and the radial width of the annular portion.

  The power tool according to claim 5 further includes a washer disposed between the retaining ring and the bearing to prevent buffering between the retaining ring and the bearing. It is characterized by being formed integrally with the washer.

  The electric power tool according to claim 6 is characterized in that the restricting means is formed on the carrier.

  The power tool according to claim 7 is characterized in that the length of the regulating means extending in the axial direction of the output shaft is more than half of the axial thickness of the annular portion. .

  According to the electric tool of the first aspect, the restricting means prevents the inner diameter of the annular portion from expanding in a state where the retaining ring is fitted in the groove portion, so that the inner diameter of the retaining ring becomes larger than the depth of the groove portion. The groove retaining ring does not come off the groove. Therefore, even when the output shaft is pulled to the output side, the retaining ring reliably contacts the bearing and the groove, so that the output shaft can be reliably prevented from coming off the bearing.

  According to the electric power tool of the second aspect, it is possible to prevent the inner diameter of the annular portion from expanding due to a simple configuration in which the regulating means abuts the outer periphery of the annular portion and the radial direction of the annular portion.

  According to the third aspect of the invention, the restricting means has a substantially cylindrical shape, and the inner diameter portion of the cylindrical portion abuts on the outer periphery of the annular portion in the radial direction of the annular portion, thereby expanding the inner diameter of the annular portion. Therefore, the inner diameter of the annular portion can be prevented from expanding with a simpler configuration.

  According to the fourth aspect of the present invention, since the inner diameter of the restricting means having a substantially cylindrical shape is smaller than the combined length of the radius of the output shaft and the radial width of the annular portion, the retaining ring has a groove portion. It does not expand to the inner diameter that comes off. Further, since the inner diameter of the restricting means having a substantially cylindrical shape is larger than the total length of the radius of the groove portion of the output shaft and the radial width of the annular portion, the restricting means can be arranged over the outer periphery of the retaining ring. it can.

  According to the electric tool of claim 5, the restricting means is formed on the washer normally disposed between the retaining ring and the bearing in order to prevent the retaining ring and the bearing from being buffered. The score can be reduced.

  According to the electric tool of the sixth aspect, since the restricting means is formed integrally with the carrier, the number of parts can be reduced.

  According to the seventh aspect of the present invention, the length of the output shaft of the restricting means extending in the axial direction is more than half the axial thickness of the annular portion. It is possible to reliably contact the outer periphery and the annular portion in the radial direction.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing the structure of the electric power tool 1 according to this embodiment. The electric tool 1 includes a motor (not shown), a motor shaft 2, a speed reduction unit 3, an output shaft 4, a tool holding unit 5, and a gear case 6.

  The motor shaft 2 transmits power from the motor to the speed reduction unit 3 as rotational torque. The speed reduction unit 3 decelerates the rotation transmitted by the motor shaft 2 and outputs it to the output shaft 4. The tool holding part 5 is attached to the front-end | tip part of the output shaft 4, and a desired tool can be attached or detached. The gear case 6 houses the speed reduction unit 3 and the output shaft 4. Specifically, a bearing 61 and a bearing 62 are disposed in the gear case 6, and the bearing 61 and the bearing 62 support the output shaft 4. In the following description, the motor shaft 2 side of the electric tool 1 is referred to as the rear, and the tool holding portion 5 side is referred to as the front.

  The speed reduction unit 3 is constituted by a three-stage planetary gear mechanism. The first stage planetary gear mechanism includes a sun gear 31a, a plurality of planetary gears 32a, an internal gear 33a, and a carrier 34a. The sun gear 31a has a cylindrical shape, and external teeth are formed on the outer periphery thereof. The planetary gear 32a has a cylindrical shape, and external teeth are formed on the outer periphery thereof. The internal gear 33a has a cylindrical shape, and internal teeth are formed on the inner periphery thereof. The carrier 34a has a disk shape, and the support shafts 35a corresponding to the number of the planetary gears 32a protrude at equal intervals from one surface, and the second-stage sun gear 31b is fixed to the other surface. Yes.

  The sun gear 31 a has a cylindrical inner periphery fixed to the motor shaft 2. The external teeth of the sun gear 31a mesh with the external teeth of the plurality of planetary gears 32a. Each planetary gear 32a is penetrated by each support shaft 35a protruding from the carrier 34a, and the positional relationship between the planetary gears 32a is maintained. Further, the outer teeth of each planetary gear 32a mesh with the inner teeth of the internal gear 33a. The internal gear 33 a is fixed to the inner surface of the gear case 6. Accordingly, when viewed from the axial direction of the motor shaft 2, the planetary gears 32a are arranged at equal intervals around the sun gear 31a, and the internal gear 33a and the gear case 6 are arranged so as to surround the planetary gears 32a. Become.

  With such a configuration, first, the sun gear 31 a is rotated by the rotational torque from the motor shaft 2. Due to the rotation of the sun gear 31a, the plurality of planetary gears 32a meshing with the sun gear 31a also rotate around the support shafts 35a. Here, even if the planetary gear 32 a rotates, the internal gear 33 a cannot be rotated because it is fixed to the gear case 6. Accordingly, each planetary gear 32a rotates about each support shaft 35a and revolves about the axis of the carrier 34a. In this way, the rotation initially applied from the motor shaft 2 is decelerated.

  Similarly, the second stage planetary gear mechanism includes a sun gear 31b, a plurality of planetary gears 32b, an internal gear 33b, and a carrier 34b, and the third stage planetary gear mechanism also includes A sun gear 31c, a plurality of planetary gears 32c, an internal gear 33c, and a carrier 34c are provided.

  On the other hand, since the sun gear 31b is fixed to the surface opposite to the support shaft 35a of the carrier 34a, the rotation decelerated by the first stage planetary gear mechanism and output from the sun gear 31b is now the second stage. Decelerated by planetary gear mechanism. Similarly, the rotation decelerated by the second stage planetary gear mechanism and output from the sun gear 31c is also decelerated by the third stage planetary gear mechanism. Thereby, the output of a desired rotational speed can be obtained.

  A carrier 34 c of the third stage planetary gear mechanism is fitted to one end of the output shaft 4, and a tool holding portion 105 to which a tip tool can be attached and detached is substantially coaxial with the motor shaft 101 at the other end of the output shaft 4. It is arranged on the top.

  FIG. 2 is an enlarged cross-sectional view of the output shaft 4. The output shaft 4 includes a fitting part 41 and an output part 42. The fitting portion 41 is fitted with the carrier 34c of the third stage planetary gear mechanism. Since the fitting part 41 and the output part 42 are integrally formed, the rotational torque transmitted from the carrier 34c to the fitting part 41 is transmitted to the output part 42 as it is.

  The output part 42 has a cylindrical shape, one bottom surface of the cylinder is formed integrally with the fitting part 41, and the other bottom surface is connected to the tool holding part 5. The output unit 42 is supported by a bearing 61 and a bearing 62. Further, a groove 43 is formed in the rear portion of the output portion 42 so as to be coaxial with the output portion 42. An annular retaining ring 44 is fitted in the groove 43 in order to prevent the output shaft 4 from being detached from the bearing 61. The retaining ring 44 is formed in a substantially C-shape formed by cutting out a part of the annular member, and the cut-out part is called a joint and the other annular part is called an annular part. The retaining ring 44 is elastically deformable. Therefore, the diameter of the retaining ring 44 can be changed with a constant width by changing the width of the joint.

  When the retaining ring 44 is fitted into the groove 43, a conical auxiliary tool is put on the rear of the fitting portion 41 in a state where the speed reduction portion 3 is not fitted to the output shaft 4. The diameter of the base of the cone is equal to the diameter of the output part 42. Therefore, by passing the retaining ring 44 through the apex of the cone and pushing it forward as it is, the retaining ring 44 expands its diameter and rides on the end of the output part 42, and further pushes forward so that it fits into the groove part 43. The

  A washer 45 is disposed between the bearing 61 and the retaining ring 44. FIG. 3 is a perspective view of the washer 45. The washer 45 is annular, and includes a cylindrical restricting means 45a that protrudes in the axial direction of the output shaft 4 along its outer periphery. The inner diameter of the restricting means 45a is larger than the outer diameter of the retaining ring 44 in a state where the retaining ring 44 is displaced from the groove part 43 and is displaced to the outer periphery of the output part 42 so that the retaining ring 44 is not detached from the groove part 43. The retaining ring 44 is larger than the outer shape of the retaining ring 44 in a state in which the retaining ring 44 is fitted in the groove 43 so that the retaining ring 44 fits within the inner diameter of the restricting means 45a. The restricting means 45 a extends in the axial direction up to about half of the thickness of the retaining ring 44. Usually, since the thickness of the retaining ring 44 is about 1 mm, the regulating means 45a extended from the washer 45 in contact with the retaining ring 44 is about 0.5 mm.

  Next, consider a case where a hole is made in wood with the electric power tool 1 having such a configuration. A woodworking cone is attached to the tool holder 5 to make a hole. When drilling a hole in the wood, the woodworking cone attached to the tool holding unit 5 is pressed against the wood, so that a pressing force is applied to the output shaft 4 from the tool holding unit 5. However, since the electric power tool 1 is structured to receive this pressing force by the bearing 62, in such a case, a thrust load is not applied to the retaining ring 44.

  On the other hand, when the woodworking cone penetrated after the drilling operation is pulled out from the wood, the cone is caught on the wood, and a tensile force from the cone is applied to the output shaft 4 via the tool holding portion 5. At this time, if the groove portion 43 is not sufficiently processed and has an R shape, the step difference of the groove portion 43 is small, or the corner of the retaining ring 44 is bent during the manufacturing process, the tensile force is Then, the force is changed to a force for expanding the retaining ring 44.

  However, according to the electric power tool 1 according to the present embodiment, even when a tensile force from the front is applied to the output shaft 4, the retaining ring 44 is elastically deformed by the restricting means 45 a of the washer 45 to expand its inner diameter. There is nothing. Thereby, it is possible to prevent the retaining ring 44 from being detached from the groove 43. Therefore, the output shaft 4 can be prevented from being detached from the bearing 61.

  The retaining ring 44 is fitted in the groove 43 with the output shaft 4 moved rearward. In this state, since the groove portion 43 is also moved rearward, there are few portions where the restricting means 45a and the groove portion 43 overlap each other when viewed from the radial direction. Therefore, the retaining ring 44 can be fitted into the groove 43 without the restriction means 45a getting in the way. On the other hand, when a tensile force from the front is applied to the output shaft 4, the output shaft 4 is pulled forward. In this case, the groove 43 is also pulled forward and the retaining ring 44 and the washer 45 come into contact with each other, so that the retaining ring 44 is held by the restricting means 45a.

  Next, a second embodiment of the present invention will be described. FIG. 4 is an enlarged cross-sectional view of the output shaft 4 of the electric power tool 10 according to the second embodiment. The power tool 10 is different from the power tool 1 according to the first embodiment in the position of the restricting means and the formed member. In the electric power tool 1 according to the first embodiment, the groove 43 is provided behind the output unit 42, but in the electric tool 10, the groove 43 is provided behind the fitting unit 41. Further, the regulating means 45 a ′ is not provided in the washer 45, but is formed as a cylindrical groove at the rear end of the third stage carrier 34 c of the speed reduction portion 3.

  Even in such a structure, similarly to the first embodiment, the restricting means 45a ′ of the carrier 34c prevents the retaining ring 44 from being expanded, so that the retaining ring 44 is prevented from coming off the groove 43. Can do. Therefore, the output shaft 4 can be prevented from being detached from the bearing 61. Further, since the regulating means 45a 'is not a cylinder but a cylindrical groove, the retaining ring 44 can be regulated with a larger force.

  The electric power tool of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

  In the first embodiment, the washer 45 is annular and includes the cylindrical restricting means 45a protruding from the outer peripheral surface thereof toward the retaining ring 44. However, the restricting means 45 may not be cylindrical. Any other structure that can regulate the expansion of the retaining ring 44 may be used. For example, as shown in FIG. 5, there may be provided restricting means 45 b protruding in the direction of the retaining ring 44 from three equally spaced locations on the circumference of the retaining ring 44. Further, the restriction means 45b is not limited to three places, and may protrude from more places.

  In the first embodiment, the restricting means 45a extends to about half the thickness of the retaining ring 44, but is not necessarily limited to half. If the retaining ring 44 is restricted, the distance may be less than half the thickness of the retaining ring 44. Further, as long as the retaining ring 44 can be fitted into the groove 43, the length may be half or more.

These are sectional drawings which show the structure of the electric tool by 1st Embodiment. These are expanded sectional views of an output shaft. FIG. 3 is a perspective view of an example of a washer. These are the expanded sectional views of the output shaft of the electric tool by a 2nd embodiment. FIG. 10 is a perspective view of another example of the washer. These are sectional drawings which show the structure of the conventional electric tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric tool, 2 Motor shaft, 3 Deceleration part, 4 Output shaft, 5 Tool holding part, 6 Gear case, 41 Fitting part, 42 Output part, 43 Groove part, 44 Stop ring, 45 Washer, 45a Control means

Claims (7)

A motor,
An output shaft to which the rotational torque of the motor is transmitted;
A bearing for supporting the output shaft movably in the axial direction;
A carrier for transmitting rotational torque from the motor to the output shaft;
A groove formed concentrically with the output shaft on the output shaft;
It has an abutment portion and an annular portion, and by changing the interval between the abutment portions, the inner diameter of the annular portion is changed to fit into the groove portion, and the output shaft comes from the bearing by abutting with the bearing. A retaining ring to prevent separation,
In the electric tool with
An electric tool comprising a restricting means for preventing an inner diameter of the annular portion from expanding in a state where the retaining ring is fitted in the groove portion.   The restricting means extends in the axial direction of the output shaft, and prevents the annular portion from moving in the radial direction and contacting the outer peripheral surface of the annular portion to expand the inner diameter of the annular portion. The power tool according to claim 1.   The restricting means has a substantially cylindrical shape, and prevents the annular portion from moving in the radial direction and the outer peripheral surface of the annular portion abutting against the inner diameter portion of the cylinder to expand the inner diameter of the annular portion. The electric tool according to claim 1 or 2, wherein   An inner diameter of the restricting means having the substantially cylindrical shape is smaller than a total length of a radius of the output shaft and a radial width of the annular portion, and the radius of the groove portion and the radius of the annular portion of the output shaft. The electric tool according to claim 3, wherein the electric tool is longer than a combined length of directions.   In order to prevent buffering between the retaining ring and the bearing, it further comprises a washer disposed between the retaining ring and the bearing, and the restricting means is formed integrally with the washer. The power tool according to any one of claims 1 to 4.   The electric tool according to any one of claims 1 to 4, wherein the restricting means is formed on the carrier.   7. The length of the restricting means extending in the axial direction of the output shaft is at least half the axial thickness of the annular portion. 8. Power tools.

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