JP2009125909A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid limitation in design when multi-speed transmission of three or more speeds is to be attained and improve freedom in setting a transmission gear ratio. <P>SOLUTION: A power tool can switch as to whether respective ring gears 14 and 19 of two planetary decelerators 1 and 2 are made unable to rotate or the gears can rotate integrally with other members while coupled with the members constituting the planetary decelerators. A switching member 15 unable to relatively rotate with the ring gear 14 of one planetary decelerator 1 of the two decelerators and capable of relatively moving in the axial direction is provided and can engage with the other member 13 by axial movement of the switching member. The other planetary decelerator has its ring gear 18 axially movable to enable the ring gear to engage with the other member. A ring integrally rotating with one of the ring gears is moved without axially moving the ring gear, thereby changing over a deceleration ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric tool including at least two planetary reduction gears and capable of switching a reduction ratio.

  Many power tools such as a drill driver have two-speed shifting in a high-speed rotation low torque mode and a low-speed rotation high torque mode. This is done depending on whether the planetary reduction gear disposed between the motor and the output shaft is in a decelerating state or a non-decelerating state.

  However, in order to cover a wider work area, it is preferable to increase the switching range of the reduction ratio or to perform multi-speed shifting of three or more stages. 1 and Patent Document 2.

  However, in the former, two of the three planetary speed reducers are composed of one carrier, two sets of planet gears, and two ring gears, so that the total length is greatly increased. On the other hand, the latter is a combination of switching of the respective deceleration states of a plurality of planetary reduction gears so that multi-stage shifting can be performed, and the increase in the overall axial length is not so large.

  By the way, when a plurality of planetary speed reducers are combined so that three or more speeds can be changed, the speed reduction ratio of a single planetary speed reducer is the same as the speed reduction ratio of another single planetary speed reducer. Since the reduction ratio of the planetary reduction gear is switched depending on whether it is in a deceleration state or a non-deceleration state (a state where the reduction ratio is 1), the obtained gear ratio is substantially reduced.

  For this reason, each planetary reduction gear must have a different reduction ratio, but this point causes the following restrictions, resulting in structural complexity and weight increase. It has been invited.

  That is, since the reduction ratio of the planetary reduction gear is determined by the number of teeth of the sun gear Zs and the number of teeth of the ring gear Zr, the outer diameter of the sun gear and the inner diameter of the ring gear are It will be determined by the reduction ratio.

  Here, planet gears are supported by moving the ring gear in the axial direction from the state in which the ring gear engages with the gear case, etc., to change the reduction ratio of the planetary reduction gear (switching to the non-deceleration state). When this is performed by engaging with a carrier that is rotating integrally with the carrier, it is necessary to match the outer diameter of the carrier with the inner diameter of the ring gear.

  The switching of the reduction ratio of the other planetary speed reducer among the two planetary speed reducers is similar to that shown in the embodiment of the present invention, in which the ring gear of the other planetary speed reducer is replaced with the carrier in the one planetary speed reducer. If the ring gears of the two planetary speed reducers, which should have different inner diameters, are engaged with a single carrier, for example, two types of engaging portions are provided on the carrier side. If the ring gears have the same inner diameter and are meshed at the same portion, the degree of freedom in setting the gear ratio is inevitably reduced.

Of course, it is also possible to engage the ring gear of each planetary reduction gear with the carrier of each planetary reduction gear instead of engaging each ring gear of different planetary reduction gears with a single carrier. However, in order to keep the ring gear meshing with the planet gear even if it slides, the axial dimension of the ring gear must be lengthened, which means that the weight of the ring gear increases and 2 Since the two ring gears are heavy together, the overall weight gain is significantly increased.
Japanese Patent No. 3696493 Special table 2004-526103 gazette

  The present invention has been invented in view of the above-described conventional problems, and can avoid a design restriction in obtaining a multi-stage shift of three or more stages, and has a high degree of freedom in setting a gear ratio. Another object is to provide a power tool that is advantageous in terms of weight reduction.

  In order to solve the above-described problems, an electric power tool according to the present invention includes at least two planetary reduction gears for deceleration, and makes each ring gear of the two planetary reduction gears non-rotatable or constitutes a planetary reduction gear. In an electric tool that is connected to another member and can be switched to be in a state of rotating integrally with the other member, and in which a multi-stage shift is possible by a combination of the above switching of both planetary reducers. One of the planetary speed reducers is provided with a switching member that is not rotatable relative to the ring gear in the planetary speed reducer and is capable of axial relative movement, and can be engaged with the other members by the axial movement of the switching member. The other planetary speed reducer of the two planetary speed reducers is characterized in that the ring gear can be moved in the axial direction and the ring gear can be engaged with the other member. One ring gear switches the reduction ratio by moving a switching member that rotates integrally with the ring gear without moving in the axial direction. In addition, the other member referred to here may be present in each of the two planetary speed reducers or may be a single entity, as will be described later.

  It is preferable that the switching member is provided in the planetary speed reducer on the front stage side. This is because the switching member can be made of a synthetic resin that is advantageous for weight reduction because the front side is faster in rotation and smaller in torque.

  The switching member may be provided on the planetary speed reducer having the smaller speed reduction ratio of the two planetary speed reducers.

  The switching member may be provided with a pin protruding in the axial direction of the planetary transmission, and the ring gear and another member may be connected by the pin. The restriction on the diameter can be further reduced.

  According to the present invention, since one planetary reduction gear can switch the deceleration state regardless of the inner diameter of the ring gear, it is possible to avoid the design restrictions due to the inner diameter as a factor. For this reason, each planetary reduction gear has a high degree of freedom in setting the reduction ratio, and avoids structural complexity and weight increase compared to those under the above constraints. Is easy.

  Hereinafter, the present invention will be described based on an embodiment shown in the accompanying drawings. FIG. 1 shows a main part of an electric power tool according to the present invention, and a speed reducer block is shown with one half of a half housing 4 removed. Shown in cross section. A motor 9 and three-stage planetary speed reducers 1, 2, 3 are housed in the housing 4 from the rear side, and a handle 8 for adjusting the tightening torque is disposed on the outer periphery of the front end portion of the housing 4. An output shaft 7 on which a chuck is mounted protrudes from the tip of the housing 4. In the figure, reference numeral 6 denotes a trigger handle, and the switch 5 is operated by the trigger handle 6.

  The three-stage planetary reduction gears 1, 2, and 3 are arranged in series in the axial direction, and the first planetary reduction gear 1 is press-fitted into the motor shaft 10 as shown in FIG. 1 sun gear 11, first planet gear 12, first carrier 13, and first ring gear 14, and the first planet gear 12 meshed with the first sun gear 11 and the first ring gear 14 is supported by a shaft 13a. The first carrier 13 is provided with first carrier engaging teeth 13b on the outer peripheral surface thereof.

  A ring 15 that is a switching member is disposed outside the first ring gear 14. The ring 15 is slidable in the axial direction, and the ring inner teeth 15 a formed on the inner peripheral surface thereof mesh with the first ring gear outer teeth 14 a formed on the outer periphery of the first ring gear 14. .

  Here, when the ring 15 is in the position shown in FIG. 2, the teeth 15b formed on the outer peripheral surface on the rear end side mesh with the teeth 24a of the gear case 24 and cannot rotate. Then, the first ring gear 15 is also in a non-rotatable state.

  The second planetary speed reducer 2 includes a second sun gear 16, a second planet gear 17, a second carrier 18, and a second ring gear 19 that are integrally formed with the first carrier 13. The second planet gear 17 that meshes with the second sun gear 16 and the second ring gear 19 is supported by a shaft 18 a provided on the second carrier 18. Further, the second ring gear 19 here is movable in the axial direction, and is in a non-rotatable state when the outer peripheral teeth 19a mesh with the teeth 25a provided on the gear case 24 as shown in FIG.

  The third planetary reduction gear 3 includes a third sun gear 20 formed integrally with the second carrier 18, a third planet gear 21, and a third carrier that supports the third planet gear 21 with a shaft 22a. 22 and the third ring gear 23, and the output is transmitted from the third carrier 22 to the output shaft 7.

  Here, the third ring gear 23 is also a component member of a ball cam clutch for adjusting the tightening torque, and when the torque applied to the third ring gear 19 exceeds a set value, the third ring gear 23 slips. The torque is not transmitted to the output shaft 7 side, but the description of this point is omitted.

  In the state shown in FIGS. 1 and 2, the ring gears 14, 18, and 23 of the first to third planetary speed reducers are incapable of rotating. For this reason, the reduction ratio of the first planetary speed reducer 1 is set to 1 / 3. If the reduction ratio of the second planetary reduction gear 2 is 1/6 and the reduction ratio of the third planetary reduction gear 3 is 1/3, the reduction ratio from the motor 9 to the output shaft 7 is 1/3 ×. 1/6 × 1/3 = 1/54.

  Now, the ring 15 is slid forward from the state shown in FIG. 2 to release the engagement between the ring 15 and the gear case 24, and the inner teeth 15a of the ring 15 are moved to the first ring gear 14 as shown in FIG. If the inner teeth 15a of the ring 15 are engaged with the engaging teeth 13b provided on the outer periphery of the first carrier 13 while being engaged with the outer teeth 14a, the ring 15 and the first ring gear 14 The first carrier 13 rotates together with the first carrier 13, and the first planetary speed reducer 1 enters a non-decelerated state. At this time, since both the second planetary speed reducer 2 and the third planetary speed reducer 3 maintain the deceleration state, the total reduction ratio is 1 × 1/6 × 1/3 = 1/18.

  On the other hand, by retracting the second ring gear 19 in the axial direction from the state shown in FIG. 2, the engagement between the external teeth 19a of the second ring gear 19 and the teeth 25a of the gear case 24 is performed as shown in FIG. When the second ring gear 19 is engaged with the engagement teeth 13b on the outer periphery of the first carrier 13 (second sun gear 16), the second ring gear 19 and the first carrier 13 (second sun gear 16) are released. And the second planetary transmission 2 are in a non-decelerated state. For this reason, the total reduction ratio is 1/3 × 1 × 1/3 = 1/9.

  Further, as shown in FIG. 5, the ring 15 is moved forward to bring the first planetary speed reducer 1 into a non-decelerated state, and the second ring gear 19 is moved backward to bring the second planetary speed reducer 2 into a non-decelerated state. For example, the speed is reduced only by the third planetary speed reducer 3 (exactly, the third planetary speed reducer 3 also serves as a tightening torque adjusting clutch, so that the clutch works). The total reduction ratio is 1 × 1 × 1/3 = 1/3.

  Depending on the combination of whether the first planetary speed reducer 1 is in a decelerating state or a non-decelerating state, or the second planetary speed reducer 2 is in a decelerating state or a non-decelerating state, the power tool has a total of four types. The total reduction ratio can be selected.

  Moreover, from the state shown in FIG. 2 in which the planetary speed reducers 1 and 2 located adjacent to each other in the axial direction are decelerating, the ring 15 in the first planetary speed reducer 1 on the rear side is advanced to move the first carrier 13. The first planetary speed reducer 1 is brought into a non-decelerated state, and the second ring gear 19 of the second planetary speed reducer 2 on the front side is retracted from the state shown in FIG. Since the second planetary speed reducer 2 is in a non-decelerated state, the movable member for switching the reduction ratio (the ring 15 and the second ring gear 19 in this example) has a stroke for the switching. Is shorter, and the operation space is accommodated in the outer peripheral portion of the first planetary speed reducer 1 and the outer peripheral portion of the second planetary speed reducer 2, although the reduction ratio can be switched over three stages. , Short overall length and compact It is intended.

  Moreover, although both the first ring gear 15 and the second ring gear 19 are connected to the first carrier 13, the first ring gear 15 is connected via the ring 15, and for this reason, the first ring gear is used. The difference between the inner diameter of 15 and the inner diameter of the second ring gear 19 does not cause a problem.

  The ring 15 is provided on the first planetary speed reducer 1 side because the first planetary speed reducer 1 rotates at a higher speed on the motor 9 side than the second planetary speed reducer 2 side, so that the torque is small. This is because there is no difficulty in making the ring 15 made of synthetic resin, which is advantageous for weight reduction. From this point of view, it is preferable that the reduction ratio of the first planetary reduction gear 1 is made smaller than the reduction ratio of the second planetary reduction gear 2. This is because the diameter of the first ring gear 14 can be made small and advantageous for weight reduction, and it is also advantageous for suppressing the outer diameter of the first planetary reduction gear 1 as a whole. However, the present invention does not prevent the arrangement of a planetary speed reducer with a large reduction ratio on the front side (input side) and a planetary speed reducer with a low speed reduction ratio on the rear side (output side). In the case of arrangement, there is no restriction on which side the ring 15 is provided.

  In the illustrated example, a pin 28 provided on the first speed change handle 27 arranged on the outer surface of the gear case 24 and protruding into the gear case 24 engages with a groove on the outer periphery of the ring 15, so that the first speed change handle 27, the ring 15 slides, and the pin 31 provided on the second speed change handle 30 similarly disposed on the outer surface of the gear case 24 engages with the groove on the outer peripheral surface of the second ring gear 19, so that the second speed change handle Although the second ring gear 19 is slid by the operation of 30, it is not limited to such a configuration, and any device can be used as long as the movable member can be moved in the axial direction. It may be. It is also possible to perform a shift by sliding the ring 15 and the second ring gear 19 by operating a single shift handle. In this case, if the speed change handle has a cylindrical shape surrounding the gear case 24 and is provided with a speed change cam of the first planetary transmission 1 and a speed change cam of the second planetary transmission 2 on the inner peripheral surface. Good. In FIG. 2, 29 and 32 are springs that urge the pins 28 and 31 in the axial direction of the planetary speed reducers 1, 2, and 3, respectively.

  6 to 9 show cross sections AA, BB, CC, and DD in FIG. However, in these cross-sectional views, the transmission handles 27 and 30 are not shown, and the tooth shape of each gear in the planetary reduction gears 1, 2, 3 is partially omitted.

  Another example is shown in FIG. Here, as the ring 15 which is a switching member, a ring 15 having a large number of pins 15d and 15e protruding in the axial direction of the planetary speed reducer 1 as shown in FIG. 14 is used, and the pin 15d of the ring 15 is a gear. The first ring gear 14 is held in a non-rotatable state by engaging with an engaging portion 24 a as a hole of the case 24 and engaging the pin 15 e with the axial through hole 14 e of the first ring gear 14.

  Further, when the ring 15 is advanced and the pin 15d is pulled out of the engaging portion 24a, at the same time when the pin 15e engages with the axial hole 13e provided in the first carrier 13 in addition to the first ring gear 14, The first ring gear 14 and the first carrier 13 are connected to each other so that they are in a non-decelerated state in which both rotate together.

  The second planetary reduction gear 2 side is the same as the previous embodiment, FIG. 10 shows the state with the largest reduction ratio, FIG. 11 shows the next largest reduction ratio, and FIG. 12 shows the next reduction ratio. FIG. 13 shows a state where the reduction ratio is the smallest.

  In each of the above examples, the first carrier 13 of the first planetary speed reducer 1 is not only a member (other member in the present invention) used for switching the reduction ratio of the first planetary speed reducer 1, but also the second carrier Although it is also a member used for switching the reduction ratio of the planetary reduction gear 2, the switching of the reduction ratio of the second planetary reduction gear 2 may use the second carrier 18 as another member.

  Moreover, the first planetary reducer 1 and the second planetary reducer 2 among the three-stage planetary reducers 1, 2 and 3 arranged in series in the axial direction switch the reduction ratio. Of course, the reduction ratio may be switched between the second planetary reduction gear 2 and the third planetary reduction gear 3, and the reduction ratio between the first planetary reduction gear 1 and the third planetary reduction gear 3. May be switched.

It is a fracture front view of an example of an embodiment of the invention. It is principal part sectional drawing same as the above. It is principal part sectional drawing of the state of the other reduction ratio same as the above. It is principal part sectional drawing of the state of other reduction ratio same as the above. It is principal part sectional drawing of the state of another reduction ratio same as the above. It is the sectional view on the AA line in FIG. It is the BB sectional view taken on the line in FIG. It is CC sectional view taken on the line in FIG. It is the DD sectional view taken on the line in FIG. It is principal part sectional drawing of another example. It is principal part sectional drawing of the state of the other reduction ratio same as the above. It is principal part sectional drawing of the state of other reduction ratio same as the above. It is principal part sectional drawing of the state of another reduction ratio same as the above. It is a perspective view of a ring (member for switching) same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st planetary gear reducer 2 2nd planetary gear reducer 3 3rd planetary gear reducer 9 Motor 11 1st sun gear 12 1st planet gear 13 1st carrier 13b Engaging tooth 14 1st ring gear 14a 1st 1 ring gear external teeth 15 ring 16 second sun gear 17 second planet gear 18 second carrier 19 second ring gear 19a second ring gear external teeth

Claims (4)

  A state in which at least two planetary speed reducers are provided for deceleration and the ring gears of the two planetary speed reducers are made non-rotatable or connected to other members constituting the planetary speed reducer and rotate integrally with the other members. In the electric power tool that enables switching of multiple planetary speed reducers by the combination of the above switching of both planetary speed reducers, the ring gear in one of the planetary speed reducers And a switching member that is relatively non-rotatable and relatively movable in the axial direction, and can be engaged with the other member by the axial movement of the switching member, and the other planetary speed reducer of the two planetary speed reducers Is a power tool characterized in that the ring gear is freely movable in the axial direction and the ring gear is freely engageable with the other member.   The power tool according to claim 1, wherein the switching member is provided in a planetary speed reducer on the front stage side.   3. The electric tool according to claim 1, wherein the switching member is provided in a planetary speed reducer having a smaller speed reduction ratio of the two planetary speed reducers.   The switching member includes a pin projecting in the axial direction of the planetary transmission, and connects the ring gear and the other member with the pin. The electric tool described.

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