JP2003206960A - Planetary transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cause no collision even in gear change during operation and generate less noises and vibration. <P>SOLUTION: Gear change is performed by change-over between the non- rotatable condition of a ring gear 32 which is freely idling in a planetary mechanism and a freely rotatable condition of the ring gear 32, and the non-rotatable operation of the ring gear 32 is performed by a one-way clutch 33. The one-way clutch 33 has a mesh-in member 332 arranged in a wedge space, an energizing spring 333 and two types of wedge spaces being different in direction of narrowing the spaces. A position restricting member 77 is arranged between both types of wedge spaces for forcibly holding the mesh-in member on the side of the wider space of the wedge spaces during movement to the side of the wider space of the wedge spaces. The mesh-in member 332 and the energizing spring 333 are arranged on both sides of the position restricting member 77, respectively, so that both of them are adapted for positive/reverse rotation with the change-over of the one-way clutch in the rotatable direction. No collision is caused because the non-rotatable operation of the ring gear is performed by the one-way clutch. Still, positive/reverse rotation is available. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planetary transmission using a planetary mechanism. 2. Description of the Related Art As a transmission, a plurality of planetary mechanisms are arranged in an axial direction, and the rotation of a plurality of members in these planetary mechanisms is selectively restricted so that outputs of different speed ratios can be obtained. There is something. Such planetary transmissions are frequently used in power tools because the input shaft and the output shaft can be arranged concentrically and can be made compact as compared with the reduction ratio obtained. By using such a transmission, the power tool can perform initial work with low torque and high speed rotation when screwing and drilling work, and final work can be performed with high torque and low speed rotation, resulting in high work efficiency. Will demonstrate. For example, Japanese Patent Application Laid-Open No. 63-101545 discloses two sun gears which are provided coaxially and rotate integrally with each other.
And two types of ring gears meshing with the respective planetary gears, and a carrier supporting both the planetary gears, and selectively rotating the two types of freely rotatable ring gears. There is disclosed a device in which an output member having a different speed ratio can be taken out from the carrier by providing a member for preventing rotation of the ring gear depending on which of the ring gears is stopped from rotating, and Japanese Patent Application Laid-Open No. 63-186054 discloses: By providing a member that switches the ring gear that moves according to the load on the ring gear and prevents rotation, the gear is automatically shifted according to the magnitude of the load without manual operation. It is shown. [0004] For this purpose, there has been proposed a device in which at least one ring gear is supported via a one-way clutch rotatable in only one direction, and the rotation of the ring gear is prevented by the one-way clutch. in this case,
The rotation of the ring gear supported by the one-way clutch is prevented by the one-way clutch without engaging the rotation preventing member. The idling of the ring gear while the rotation of the other ring gear is stopped is in the direction in which the one-way clutch is freely rotatable, so that no problem occurs. [Patent Document 1] Japanese Patent Application Laid-Open No. 63-101545 [Patent Document 2] Japanese Patent Application Laid-Open No. 63-186054 SUMMARY OF THE INVENTION The output is taken out by the ring gear that stops the rotation and the planet gear that meshes with the ring gear. The ring gear that has not stopped rotating is idle while taking out the output. For this reason, during the shifting operation, the rotation of the ring gear during idling is forcibly stopped, and at this time, the engagement portion provided on the ring gear is Since the rotation of the ring gear is stopped by engaging the rotation preventing member, a collision occurs between the ring gear and the rotation preventing member. The life of the rotation preventing member is reduced. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a planetary transmission which does not cause a collision even during a gear shift during operation and has little noise and vibration. is there. According to the present invention, a speed change is performed by switching between a rotation preventing state of a freely rotatable ring gear in a planetary mechanism and a free rotation state of the ring gear. In the planetary transmission in which the rotation of the ring gear is prevented by a one-way clutch, the one-way clutch includes an outer race, an inner race, and a mesh including rollers, balls, and the like disposed in a wedge-shaped space formed between the two races. And a biasing spring for pushing the biting member toward the narrower side of the wedge-shaped space, and two types of wedge-shaped spaces in which the direction in which the space narrows are different from each other. It is movable in the wedge-shaped space, and when moving to the wider space side in the wedge-shaped space, the biting member is forcibly retained in the wider space side in the wedge-shaped space. A position restricting member is disposed between the two types of wedge-shaped spaces, and a biting member and an urging spring are disposed on both sides of the position restricting member, so that the rotatable direction of the one-way clutch can be switched, and It is characterized in that the switching corresponds to both forward and reverse rotations. According to the present invention, since the rotation of the ring gear supported by the one-way clutch is prevented by the one-way clutch without engaging the rotation preventing member, no collision occurs. The direction of rotation of the one-way clutch can be switched. In order to cope with both forward and reverse rotation by this switching,
The present invention can also be applied to a function requiring forward / reverse rotation functionally, such as an electric screwdriver. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment for an electric power tool such as an electric drill driver shown in the drawings. A motor 6 disposed at one end opening side of a gear case 1 will be described.
The output shaft 60 has two sun gears 11 having different numbers of teeth.
12 are fixed and these sun gears 1 are arranged in the axial direction.
A plurality of planet gears 21 and 22 mesh with the planet gears 1 and 12, respectively. The two planetary gears 21 and 22 having different numbers of teeth are both supported by the carrier 4. The planetary gears 21 are supported at equal intervals around the sun gear 11, and the planetary gears 22 are supported at equal intervals around the sun gear 12. Thus, the two planetary gears 21 and 22 individually rotate, but perform the same revolution. A planet gear 21 meshes with a ring gear 31 arranged concentrically with the output shaft 60, and a ring gear 32 similarly arranged concentrically with the output shaft 60 meshes with the planet gear 22. Of these two ring gears 31 and 32 arranged in the axial direction, the ring gear 31 has a plurality of engagement projections 35 on its outer peripheral surface as shown in FIGS.
Are formed at equal intervals in the circumferential direction, and are freely rotatable with respect to the gear case 1. Ring gear 3
The ring gear 32 also has an inner race 3 of a one-way clutch 33 with the gear case 1 as an outer race 330.
31. The one-way clutch 33 here is
As described above, the gear case 1 is the outer race 330, the ring gear 32 is the inner race 331,
A freewheel type formed by disposing balls 332 in a wedge-shaped space formed between 0 and 331;
While having two kinds of wedge-shaped spaces with different narrowing directions,
A drive piece 77 protruding from the forward / reverse switching ring 76 is located between the two types of wedge-shaped spaces. The forward / reverse switching ring 76 is rotated with respect to the gear case 1 to be positioned on both sides of the drive piece 77. The rotatable direction of the ring gear 32 as the inner race 331 can be switched depending on which of the pair of balls 332 and 332 is pressed by the driving piece 77. That is, when the driving piece 77 pushes the ball 332 on one side into the wide portion of the wedge-shaped space as shown in FIG. 9, the other ball 332 is positioned in the narrow portion of the wedge-shaped space by the bias of the spring 333. In this state, the rotation of the ring gear 32 (the inner race 331) in the direction of the arrow A in the figure is possible, but the rotation of the ring gear 32 in the direction of the arrow B in the figure is prevented. When the driving piece 77 pushes the ball 332 on the right side in the figure to the right in the figure, the ring gear 32 (inner race 331) in the direction of the arrow B in FIG. Is prevented from rotating. In the gear case 1, in addition to the planetary mechanism, the forward / reverse switching ring 76 and the one-way clutch 33, a locking ring 70 is provided. As shown in FIGS. 6 and 8, the locking ring 70 slidable in the axial direction includes a projection 71 that engages with the engagement projection 35 on the outer peripheral surface of the ring gear 31 when moved in one direction. The engagement prevents rotation of the ring gear 31 and allows the ring gear 31 to rotate when the engagement between the engagement projection 35 and the projection 71 is released by the slide. The sliding of the locking ring 70 in the axial direction includes the switching drive member 7 such as a solenoid shown in FIGS. 8 and 11 and the switching drive member 7 which is pivotally supported on the outer surface of the gear case 1 by the shaft 66 and has one end. The other end is formed by a lever 65 connected to a connecting shaft 72 projecting from the outer peripheral surface of the locking ring 70. The carrier 4 supporting the planetary gears 21 and 22 has a sun gear 41 integrally therewith. The rotation of the sun gear 41 supports a planetary gear 42 meshing with the sun gear 41 and the ring gear 43. The rotation of the carrier 44 is transmitted to the output shaft 5 through the auto lock mechanism 55. The auto lock mechanism 55 has a function of automatically locking the output shaft 5 to the gear case 16 when the rotation of the motor is stopped, and automatically releasing the lock when the motor is rotated. However, description of this point is omitted. Further, the ring gear 43 is also freely rotatable,
By engaging the ball 48 with the ring gear 43 with the spring pressure of the clutch spring 47, a torque limiter is configured to disconnect the output shaft 5 and the sun gear 41 when the load torque exceeds a predetermined value. However, description of this point is also omitted. Now, as shown in FIG.
0 prevents the rotation of the ring gear 31 and the one-way clutch 33 is set so that the ring gear 32 can rotate in the direction indicated by the arrow in the figure. Is transmitted to the carrier 4 through the planetary gear 21 meshed with the ring gear 31 whose rotation is prevented. At this time, the ring gear 32 is connected to the output shaft 5
The idle rotation is the direction in which the rotation indicated by the arrow in the figure is permitted. The switching drive member 7 operates in response to an increase in the load detected by the rotation speed detecting means of the motor 6, and the locking ring 70 moves and engages as shown in FIG. When the engagement between the projections 35 and the projections 71 is released, the ring gear 31 becomes free, and the stop of the carrier 4 connected to the load causes the rotation of the planetary gears 21 and 22 meshing with the sun gears 11 and 12 to rotate. At this time, the rotation direction of the ring gear 32 is as follows.
In the direction opposite to the above-mentioned idle rotation, that is, the one-way clutch 3
3, the power is transmitted to the carrier 4 and the output shaft 5 through the planetary gears 22 meshed with the ring gear 32 from this point. Since the number of teeth of the sun gear 12 is smaller than the number of teeth of the sun gear 11 and the number of teeth of the planetary gear 22 is larger than the number of teeth of the planetary gear 21, the state of high-speed rotation and low torque is changed to low-speed rotation and high torque. It has been switched. In addition, in this shifting, the rotation of the ring gear 32 is stopped by using the one-way clutch 33, so that only the locking ring 70 is separated from the locking projection 35 of the ring gear 31. Therefore, a smooth and noise-free shift can be performed despite the fact that there is no member causing the shift. The return from the low-speed rotation high-torque state to the high-speed rotation low-torque state is performed by the return of the switching drive member 7, and this shift is performed when the motor 6 is stopped or when the motor 6 is started. By rotating the forward / reverse switching ring 76,
When the rotation direction of the one-way clutch 33 is reversed and the rotation direction of the motor 6 is reversed,
Power is transmitted to the carrier 4 through the planetary gear 21 meshing with the ring gear 31 whose rotation is stopped by the locking ring 70. At this time, the ring gear 32 idles in the rotatable direction in the one-way clutch 33, and the load increases. When the switching drive member 7 is activated by detection and the ring gear 31 becomes free, power is transmitted to the carrier 4 through the ring gear 32 whose rotation is prevented by the one-way clutch 33 and the planetary gear 22 meshing with the ring gear 32. Although there is only one one-way clutch 33, the same operation can be obtained in forward rotation and reverse rotation required of the electric drill driver by switching the rotation prevention direction. If the motor 6 is rotated only in one direction, the one-way clutch 33 need not be able to switch the rotation prevention direction. The forward / reverse switching ring 76 in the illustrated example is used.
Is a rotation direction switching rod 8 shown in FIG.
The switching lever 90 has the other end engaged with the forward / reverse switching ring 76. The rotation direction switching rod 8 here is also linked with the switch unit SW shown in FIG. 11, so that the rotation direction of the motor 6 is switched at the same time. The switch unit SW also controls the energization of the motor 6 when the trigger switch handle 9 is pulled, and also controls the rotational speed of the motor 6 in accordance with the amount of pulling the trigger switch handle 9. Is omitted. Further, although the slide driving of the locking ring 70 for shifting is performed by the switching drive member 7, the invention is not limited to this, and it may be performed manually. In the case where the outer race 330 of the one-way clutch 33 is also used as the gear case 1, the gear case 1 is not a simple container but requires a high strength.
It must be made of metal. On the other hand, a surface for forming a wedge-shaped space must be formed on the inner surface of the gear case 1,
Since the inner surface shape is complicated, cutting becomes difficult.
For this reason, here, the gear case 1 is formed as a molded product made of a sintered metal to cope with this point and to avoid an increase in cost. Gear case 1 is usually
Although the number of components is as small as possible, the ring is used to reduce the mechanism loss by eliminating the sliding resistance between the forward / reverse switching ring 76 and the ring gear 32 while securing the operation space of the forward / reverse switching ring 76. If the projection 13 serving as the thrust receiving surface of the gear 32 is also provided on the gear case 1, the formability of the gear case 1 becomes extremely poor. The projection 13 is also formed integrally with the lid member 10 fitted to one end of the gear case 1. Note that in the illustrated example, 3
The individually provided projections 13 also have a function of positioning and centering the lid member 10 with respect to the gear case 1. FIGS. 2 to 7 show the order of assembling the parts into the gear case 1 and the switching lever 9.
After mounting the cover member 10 and the cover member 10, as shown in FIG. 3, the forward / reverse switching ring 76 and the carrier 4 are put in, and then, as shown in FIG. As shown in FIG.
After the ring gear 31 and the locking ring 70 are placed in this order as shown in FIG. 6, the thrust plate 19 is placed as shown in FIG.
Attach and assemble. The gear case 1 having the above-mentioned shape may be formed not as a molded product made of a sintered metal but as a laminate of metal annular thin plates. By laminating metal sheets punched in the required shape, the required shape is obtained.
Also in this case, the production becomes easy and the cost can be reduced. Further, if the entire gear case 1 is made of metal, a new problem arises in terms of weight. However, a portion requiring strength, that is, the outer race 3 of the one-way clutch 33 is required.
Only the portion 30 is made of metal and the other portions are made of synthetic resin to reduce the weight. In this case, it is preferable to insert-mold the metal portion. As described above, in the present invention, the ring gear supported by the one-way clutch is prevented from rotating by the one-way clutch without engaging the rotation preventing member, so that a collision occurs. Without
Therefore, a smooth shifting operation can be performed, and the one-way clutch can switch its rotatable direction and cope with forward / reverse rotation. It can also be applied to those that can be used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing one embodiment. FIG. 2 is a rear view of the same gear case and lid member. FIG. 3 is a rear view showing a state where a forward / reverse switching ring and a carrier are incorporated in the gear case. FIG. 4 is a rear view showing a state in which a one-way clutch component, a ring gear, and a planetary gear are further incorporated into the gear case. FIG. 5 is a rear view showing a state where another ring gear and a planetary gear are incorporated in the gear case. FIG. 6 is a rear view showing a state where a locking ring is further incorporated in the gear case. FIG. 7 is a rear view showing a state where a thrust plate is further mounted on the gear case. 8 (a) is a perspective view showing a state before shifting, and FIG. 8 (b) is a perspective view showing a state after shifting. FIG. 9 is an explanatory diagram of a rotation direction switching portion of the one-way clutch of the above. FIG. 10 is a cross-sectional view showing a rotation direction switching operation unit in an electric tool including the planetary transmission according to the present invention. FIG. 11 is a partially broken side view of the electric power tool. [Description of Signs] 1 Gear case 22 Planetary gear 32 Ring gear 33 One-way clutch

Claims (1)

Claims: 1. A speed change is performed by switching between a rotation preventing state of a freely rotatable ring gear in a planetary mechanism and a free rotation state of the ring gear, and the rotation of the ring gear is prevented from rotating. In a planetary transmission using a one-way clutch, the one-way clutch includes an outer race, an inner race, and a meshing member including rollers, balls, and the like disposed in a wedge-shaped space formed between the two races. A biasing spring for pushing the member into a narrower side of the wedge-shaped space, and two types of wedge-shaped spaces in which the space narrows in different directions. A wedge-shaped position regulating member that forcibly holds the biting member to the wider space side of the wedge-shaped space when moving to the wider space side in the wedge-shaped space The one-way clutch can be rotated in both forward and reverse directions by arranging a biting member and an urging spring on both sides of the position regulating member, respectively. A planetary transmission, characterized in that: