JPH0612268Y2 - Multi-speed transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial field of application> The present invention relates to a transmission using a planetary gear, and more particularly, to an eccentric shaft and a plurality of external gears and internal gears that are internally meshed with each other. The present invention relates to a multi-stage transmission that combines the above.

<Prior Art> In a power seat device in which a vehicle seat is driven by an electric motor to adjust the position, it is necessary to obtain a very large reduction gear ratio. However, in the conventional speed reducer in which a large number of gear trains are combined in multiple stages, there is a problem that the entire device is complicated, large and heavy, and the mechanical loss of drive torque is large as well as the reduction of space efficiency and increase of manufacturing cost. there were. Therefore, for example, as disclosed in Japanese Patent Laid-Open No. 63-285350, there is disclosed a speed reducer using a planetary gear that is small in size and obtains a high reduction ratio.

On the other hand, when a plurality of internal gears and external gears are combined on substantially the same shaft, there is a problem with the means for defining the axial position of the intermediate gear. According to the structure disclosed in the above publication, the gears are configured so as to overlap each other in the axial direction, and then the gears are collectively prevented from coming off by the stop ring fitted to the central shaft.

However, according to this structure, the external gear member must be engaged with the axial end surface of the internal gear member after being overlapped with it, and also engaged with the central shaft, so that the overall shape of the gear member is complicated. In addition, the size of the reduction gear in the axial direction has to be increased. Moreover, since the second-stage external gear is simply slidably fitted on the outer periphery of the first-stage internal gear that also serves as an eccentric shaft, the sliding friction generated between them causes the driving force transmission efficiency to increase. However, there is a problem that it is lowered and smooth operation cannot be ensured.

<Problems to be Solved by the Invention> Therefore, an object of the present invention is a multi-stage type that can achieve a smaller size and a higher reduction ratio and can reduce mechanical loss and ensure smooth operation and torque transmission. It is to provide a transmission.

According to the present invention, there is provided an eccentric shaft that is eccentric with respect to the axis of the input shaft, and a plurality of first pin holes formed concentrically with the axis of the eccentric shaft. A first external gear that is rotatably supported by the eccentric shaft, and a first internal gear that is internally meshed with the first external gear and is eccentric with respect to the axis of the eccentric shaft. A second external gear having a plurality of second pin holes formed concentrically with the axis of the eccentric shaft and rotatably mounted on the outer periphery of the first internal gear, and the eccentric shaft A second internal gear that is arranged concentrically with the axial center of the first external gear and internally meshes with the second external gear, and is slidably fitted into the first pin hole of the first external gear. A fixed plate having a plurality of first pins and a plurality of second pins that are respectively loosely fitted in the second pin holes of the second external gear so as to be slidably contactable with each other; In the multi-stage transmission, the first external gear and the second external gear are engaged with flanges formed at the free ends of the corresponding first and second pins, respectively. A plurality of rolling elements are interposed between the outer peripheral portion of the first internal gear and the inner peripheral portion of the second external gear, and the rolling bodies and the first internal gear are retained. The present invention is achieved by providing a multi-stage transmission that is prevented by a radially inwardly projecting edge portion formed over the entire circumference of the inner peripheral portion.

<Operation> With this configuration, the rolling element can be used without increasing the size of the device, and the sliding friction generated between the first-stage internal gear and the second-stage external gear is significantly reduced. Can be reduced to

Moreover, since the axial position of each gear can be defined without overlapping each other, the device can be thinned.

<Embodiment> Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

A speed reducer to which the present invention is applied includes an eccentric shaft 2 that is integral with an input rotary shaft 1, a first external gear 3 and a first internal gear 4 that form a first speed reducer, and a second speed gear. A second external gear 5 and a second internal gear 6 that form a speed reducer, and a fixed disk 7 are provided. The first external gear 3 is provided with a central hole 8 into which the eccentric shaft 2 is relatively rotatably fitted, and four first pin holes 9 arranged at equal intervals on a concentric circle around the central hole 8. There is. First
The inner circumference of the internal gear 4 has a sinusoidal tooth profile 1 with the number of teeth 1
0 is formed, and a sinusoidal tooth profile 11 having one less number of teeth Ni1 than that of the first internal gear 4 is formed on the outer periphery of the first external gear 3 that meshes therewith. The first internal gear 4 is eccentric in the same direction as the eccentric shaft 2 with respect to the input rotary shaft 1 and by the same distance e.

The second external gear 5 has a central hole 12 into which the first internal gear 4 functioning as an eccentric shaft of the second stage is fitted, and four second central holes 12 arranged at equal intervals on a concentric circle. The pin hole 13 is formed. The second internal gear 6 has a sinusoidal tooth profile 14 having a No2 number of teeth, and a second tooth meshing with the tooth profile 14.
On the outer periphery of the external gear 5, a Ni2 sinusoidal tooth profile 15 having one fewer teeth than the second internal gear 6 is formed.
Further, the fixed circular plate 7 is provided with a central hole 17 through which the input rotary shaft 1 passes, and the one side surface 16 is provided with the central hole 17.
Four first pins 18 corresponding to the first pin holes 9 of the first external gear 3 on the concentric circles, and second pins of the second external gear 5 arranged on the outer concentric circles at equal intervals. Four second pins 19 corresponding to the holes 13 are projectingly provided.

As well shown in FIGS. 2 and 3, the eccentric shaft 2 in which the input shaft 1 is rotatably pierced through the central hole 17 of the fixed disc 7 is provided with the first external gear 3. The first pins 18 of the fixed disk 7 are slidably fitted in the corresponding first pin holes 9 so as to be slidable and relatively rotatably fitted and supported. In the second external gear 5, the center hole 12 is fitted into the first internal gear 4 that meshes with the first external gear 3, and the second pin 19 of the fixed plate 7 is inserted into each second pin hole 13. It is mounted by being loosely fitted so that it can slide. Then, a second internal gear 6 connected to an output shaft (not shown) meshes with the second external gear 5 and is rotatably mounted on the fixed disc 7. In addition, the first external gear 3 and the second
The external gear 5 is prevented from coming off by flanges 20 and 21 attached to the tips of the first and second pins 18 and 19 loosely fitted in the pin holes 9 and 13, respectively. An annular plate 26 having an inner diameter smaller than that of the fixed plate 7 extending inward in the radial direction so as to cover the outer peripheral edge portion of the fixed plate 7 from the outside is fixed to the outer end of the second internal gear 6. Thus, the second internal gear 6 is properly held on the fixed plate 7.

A large number of rolling elements 22 made of steel balls as shown in FIG. 4 are interposed between the outer circumference of the first internal gear 4 and the inner circumference of the second external gear 5 which rotate relative to each other. ing. In the center hole 12 of the second external gear, there is formed a ridge 23 extending inward in the radial direction so as to overlap with the first internal gear 4 so as to overlap with the outer surface of the second external gear. Has been done. And
A step portion 24 corresponding to the projecting edge 23 is formed in the peripheral portion of the first internal gear 4. Therefore, the steel balls 22 can be prevented from coming off while keeping the wall thicknesses of the first internal gear 4 and the second external gear 5 thin. The rolling element 25 is also provided between the outer periphery of the eccentric shaft 2 and the center hole 8 of the first external gear 3 with a similar retaining structure. With this configuration, the reduction gear is held thin and the sliding resistance between the eccentric shaft 2, the first external gear 3, and the first internal gear 4 and the second external gear 5 is reduced. The smoother operation and torque transmission can be ensured, and the first internal gear 4 is prevented from coming off by the projecting edge 23 of the second external gear 5.

When the eccentric shaft 2 is rotated by driving an electric motor (not shown) connected to the input shaft, the movement of the first external gear 3 is restricted by the first pin 18 slidingly contacting the first pin hole 9. Instead of rotating, the sliding friction between the eccentric shaft 2 and the center hole 8 causes the input rotating shaft 1 to swing about its axis. By the swing of the first external gear 3, the first internal gear 4 is decelerated with respect to one rotation of the eccentric shaft 2 and rotates 1 / No1 in the same direction. When the first internal gear 4 rotates as an eccentric shaft, the second external gear 5 is also slidably brought into contact with the second pin hole 13 by the second pin 19 due to sliding friction between the first internal gear and the center hole 12. Since the movement is restricted, it swings around the axis of the input rotary shaft 1 without rotating. Due to the swing of the second external gear 5, the second internal gear 6 causes the first internal gear 4 to rotate once for one rotation of the second external gear 5.
That is, it rotates 1 / No2 in the same direction as the eccentric shaft 2. Therefore,
According to the speed reducer of this embodiment, a high speed reduction ratio of 1 / No1 · No2 can be obtained.

FIG. 5 discloses a suitable rolling pin structure for reducing the sliding resistance between the pin hole and the pin in sliding contact therewith. This pin structure has a lock pin 31 fixed to the fixed disc 7 and a sliding pin 32 inserted into a pin hole of an external gear.
And a roller 33 fitted to the sliding pin 32.
The lock pin 31 and the sliding pin 32 each have flanges 34 and 35 at one end. Further, the sliding pin 32 has an axial hole 36 of the same diameter as the lock pin 31 which is opened at the other end.
And four grooves 37 having a semicircular cross section, which are provided on the outer peripheral surface of the groove 37 along the axial direction. In each groove 37, a large number of steel balls 38 are arranged between the groove 33 and the roller 33 as described later.

This pin structure is shown in FIG. 6 as the pin hole 1 of the first external gear 3.
The state used for 0 is shown. The lock pin 31 is
The flange 35 is sufficiently press-fitted and fixed in the hole 39 of the fixed disk 7 to a position where it comes into contact with the side surface of the fixed disk 7. Into the first pin hole 9, a sliding pin 32 in which a large number of steel balls 38 are arranged in each groove 37 and a roller 33 is rotatably fitted is inserted, and the fixed pin 31 protruding from the fixed disc 7 is inserted. Is fitted into the axial hole 36 and integrally joined. Since the outer diameter of the flange 35 of the sliding pin 32 is larger than that of the roller 33, the roller 33 can be prevented from coming off and the first external gear 3 can be held at a predetermined position on the fixed disc 7. By using this small rolling pin structure, the sliding resistance between the pin and the pin hole can be greatly reduced, so that the driving torque transmission efficiency can be greatly improved.

[Advantage of the Invention] As described above, according to the present invention, the first and second external gears are locked to the flange formed at the free end of the pin fixed to the fixed disc. The eccentric shaft and the external gear that rotate relative to each other are fitted together via rolling elements to prevent slipping out, and the projecting edge portion that radially extends to the inner peripheral portion of the external gear and the outer peripheral portion of the eccentric shaft. By providing the retaining structure including the step portion and the complementary step portion, it is possible to improve the transmission efficiency of the drive torque while achieving the thinning of the device.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a speed reducer to which the present invention is applied. FIG. 2 is a front view of a speed reducer according to the present invention. FIG. 3 is a sectional view taken along the line III-III in FIG. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is an exploded perspective view of the rolling pin structure. FIG. 6 is a sectional view showing a usage state of the rolling pin structure of FIG. DESCRIPTION OF SYMBOLS 1 ... Input shaft 2 ... Eccentric shaft 3 ... 1st external gear, 4 ... 1st internal gear 5 ... 2nd external gear, 6 ... 2nd internal gear 7 ... Fixed disc, 8 ... Center hole 9 ... 1st pin hole, 10, 11 ... Tooth profile 12 ... Center hole, 13 ... 2nd pin hole 14, 15 ... Tooth profile, 16 ... Side surface 17 ... Center hole, 18 ... 1st pin 19 ... 2nd pin, 20, 21 ... Flange 22 ... Steel ball, 23 ... Projection edge 24 ... Step, 25 ... Steel ball 26 ... Annular plate, 31 ... Fixing pin 32 ... Sliding pin, 33 ... Roller 34, 35 ... Flange, 36 ... Axial hole 37 … Grooves, 38… Steel balls 39… Holes

Claims (1)

[Scope of utility model registration request] 1. An eccentric shaft that is eccentric with respect to the axis of the input shaft,
A first external gear having a plurality of first pin holes formed concentrically with the axis of the eccentric shaft and rotatably supported by the eccentric shaft; A first internal gear that meshes with each other and is eccentric with respect to the axis of the eccentric shaft, and a plurality of second pin holes formed concentrically with the axis of the eccentric shaft, and the first internal gear. A second externally toothed gear mounted on the outer periphery of the rotatably relatively, and a second internally toothed gear arranged at a position concentric with the axis of the eccentric shaft and internally meshing with the second externally toothed gear. A plurality of first pins loosely fitted in the first pin holes of the first external gear and slidably fitted in the second pin holes of the second external gear. A multi-stage transmission including a fixing plate having a second pin, wherein the first external gear and the second external gear are paired with each other. Corresponding to the first pin and the second pin, which are engaged with flanges formed at the free ends of the first pin and the second pin to prevent disengagement, and the outer peripheral part of the first internal gear and the inner peripheral part of the second external gear. A plurality of rolling elements are interposed between the rolling elements, and the rolling elements and the first internal gear are prevented from coming off by a radially inward projecting edge portion formed on the inner circumferential portion over the entire circumference. A multi-stage transmission characterized in that