JPS5930938B2 - planetary gearbox - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a planetary gear device having a structure in which a disk and a ring equal to the pitch circle are added to both sides of the gear, and in particular, the gear portion and the disk of the planetary gear are independently connected to the planetary shaft. Regarding what is supported.

A planetary gear system in which a planetary gear and an external shell internal gear are provided with a disk or ring having the same diameter as the pitch circle on both sides of the planetary gear is already known (Japanese Patent Publication No. 17111/1983).

FIG. 6 shows a sectional view of such a planetary gear device.

This includes a sun gear 31, a planetary gear 32, and an outer shell internal gear 3.
3. Consists of a carrier 34 that pivotally supports the planetary gear.

The planetary gear 32 includes a flexible ring-shaped planetary gear 36,
On both sides thereof, there are planetary disks 37 having a pitch diameter and supporting the planetary gears 36 by means of annular notches bulging inward.

The outer shell internal gear 33 consists of a central outer shell gear 38 and outer shell rings 39 each having an inner diameter of a pitch circle provided on both sides of the outer shell gear 38.

The planetary disk 37 rolls on the outer shell ring 39 along a pitch circle.

Radial forces such as centrifugal force are transmitted from the planetary disk 37 to the outer shell ring 39, thereby preventing eccentric movement of the carrier.

Torque is transmitted through the planetary gear 36, the planetary shaft 35, and the outer shell gear 38.

Since radial force is not applied due to gear meshing, requirements for gear dimensional accuracy and carrier division accuracy are not strict.

In this way, the requirement for strict consistency of meshing conditions, which is an inherent difficulty of planetary gear devices, can be alleviated.

However, in this structure, the planetary gear 36 does not come into contact with the planetary shaft 35, but is supported by a boss portion (annular notch) 40 that bulges inwardly of the planetary disk 37.

This is to make the gear as unrestricted as possible, reduce the tooth thickness, and make the tooth tip more flexible, so that matching conditions can be easily achieved.

The inventor has realized that such a planetary gear arrangement, in which the planetary gears are indirectly supported, still has drawbacks.

Although such devices are supposed to mesh smoothly and generate little heat, they can sometimes generate a considerable amount of heat during operation.

Another drawback is that when used for a long time, the back surface of the planetary gear, that is, the part of the disk 37 that contacts the internal force bulging boss 40, is subject to significant wear.

The present inventor considered the cause of wear at the contact portion between the planetary gear and the planetary disk.

Ideally, the planet disks have a size equal to the pitch circle of the planet gear, the outer shell ring has an inner diameter equal to the pitch circle of the outer shell gear, and all planet disks are always in contact with the outer shell ring. I'm sure they are.

Therefore, the planetary disk and the planetary gear always rotate at the same speed, and no slippage occurs between them.

However, the rings and disks are not perfect circles and have dimensional errors, and expansion and contraction due to temperature must be taken into consideration.

In order for both to roll smoothly, a clearance must be maintained between them.

The planetary disk must be slightly smaller than the pitch circle, and the outer shell ring must be slightly thicker than the pitch circle of the outer internal gear.

A clearance is also provided between the planetary shaft 35 and the through hole 41 of the planetary disk 37.

Regarding the gear 36 and the disk 37 that constitute the planetary gear 32,
The rotation of the gear 36 is accurate because the gears mesh with each other.

However, the rotation of the disk 37 is accompanied by uncertainty.

The force that rotates the disc 37 at the same speed as the gear 36 is
This is caused by a contact friction force F1 between the disk 37 and the outer shell ring 39, and a contact friction force F2 between the disc 37 and the gear 36.

There is also a force that suppresses the rotation of the disk 37.

These are the frictional force between the planetary shaft 35 and the through hole 41, and the frictional force F3 between the carrier inner wall.

If the rotational friction force (F1+F2) is thicker than the braking friction force F3, the disc rotates at the same speed as the gear.

If (F1+F2) is smaller than the braking frictional force F3, the disk 37 is restrained by the floating shaft 35 and the carrier and does not rotate one rotation.

However, what is referred to as frictional force here refers to the frictional force moment, which is abbreviated as follows for simplicity.

It is fine if F1+F2>F3 is always (1), but since these are frictional forces, they fluctuate rapidly, and this is not the case even when visiting.

Since there is a clearance between the disk, the outer shell ring, the planetary shaft, etc., not all of the planetary disks are always in contact with the outer shell ring 39.

For the disc that is separated from the outer shell ring, it becomes Fl-0.

In such a case, F1+F2<F3...
...(2) is likely to occur.

The disk then sticks to the planetary shaft and does not rotate, and slippage occurs at the contact surface between the disk and the gear, generating heat and causing the contact surface to wear out.

Unfortunately, Fl between the outer ring and the disk is unrelated to the force applied to the planetary shaft, but F2 and F3 are proportional to the normal force f1 between the planetary shaft and the disk, that is, the transmitted torque T. .

This is quite thick. If the friction coefficients between the planetary shaft and the disc, and between the disc and the gear are μ and μ', then the frictional forces F2 and F3 are F2=μf (3)
F3=μf (4)
It can be written as

Since the frictional force F1 between the outer shell ring and the disk is not proportional to f,
If μ>μ', there is a greater possibility that the braking frictional force F3 will prevail.

Carrier transmission torque T is calculated as T=NfR, where the number of planetary gears is N1 and the distance between the planetary axis and the sun gear axis is R.
・It is related to the normal force f by (5).

As the transmission torque T increases, the slippage between the planetary disc and the planetary gear and the heat generation become more significant.

This is because the frictional force applied to the sliding surface is proportional to the torque, as shown in equation (3), and this is proportional to the frictional work.

Then, it seems that it would be better to make the connection between the disc and the gear tighter.

This is because μ'>μ, and the disc/gear frictional force F2 becomes large, so that inequality (2) is always satisfied.

However, one in which the disc and the gear are integrated is undesirable because of frictional braking force.

The disk is slightly smaller than the pitch circle of the planetary gear, and the outer shell ring is slightly thicker than the pitch circle of the outer shell gear.

If the disc rolls in contact with the outer shell gear, it must rotate somewhat faster than the planetary gear.

However, if the disk and gear are closely integrated, they cannot rotate independently, and this acts as a braking force for the planetary gear.

This braking force reduces the power transmission efficiency of the entire planetary gear system.

Ultimately, the most desirable thing is to combine the planetary disk and planetary gear that constitute the planetary gear so that they can rotate independently,
The frictional force F2 between them should be small, and the frictional force F3 between the disk and the planetary shaft should also be small.

The present invention has been made in response to such demands.

In the present invention, both the planetary gear part and the planetary disk have a simple disk shape, and are independently supported by the planetary shaft,
The force f applied to the planetary gear part is not applied to the planetary disk at all,
The frictional force between the planetary shaft and the planetary disk is small, and the frictional force between the disk and the gear is also small, providing an entertainment gear device without heat generation or wear.

EMBODIMENT OF THE INVENTION Hereinafter, the structure, operation, and effect of the present invention will be explained in detail with reference to drawings showing examples.

FIG. 1 is a partially cutaway front view of a planetary gear device according to Embodiment I of the present invention, FIG. 2 is a partially cutaway rear view, and FIG.
It is an XOY sectional view in the figure.

This planetary gear device consists of a sun gear 1 at the center, a plurality of planet gears 2 surrounding and meshing with the sun gear 1, an internal gear 3 in the outer shell that is in the outermost shell and meshing with the planet gears 2, and a shaft supporting the planet gears. It consists of carrier 4.

The planetary gear 2 includes a planetary gear 6 at the center outer periphery provided with teeth,
A gear receiver on the inner circumference interposed between the planetary gear 6 and the over-lift shaft 5 fixed to the carrier 4 is provided on both sides of the ring 7 and the planetary gear 6, and is equal to the pitch circle of the planetary gear 6. It consists of a planetary disk 8 having an outer diameter.

The planetary gear 6 and the gear receiver are rotatably supported by the planetary shaft 5 completely independently of the ring 7 and the planetary discs 8, 8.

The outer shell internal gear 3 consists of a central outer shell gear 9 provided with teeth, and outer shell rings 10 provided on both sides of the gear and having an inner diameter equal to the pitch circle of the outer shell gear 9.

However, although the planetary disk 8 and the outer shell ring 10 are said to have outer and inner diameters equal to the pitch circles of the planetary gear 6 and the outer shell gear 9, an appropriate rear balance must be taken of course.

Since the carrier 4 pivotally supports the planetary gear 2 from both sides by the planetary shaft 5, it is formed by integrally combining a disk-shaped A carrier 11 and a B carrier 12 on both sides of the planetary gear.

At the center of the sun gear 1 and carrier 4, a sun shaft hole 13 and a carrier shaft hole 14 are formed in a rotation-preventing shape (spline, serration, key structure, D-shaped hole, etc.).

Attach the input/output shaft (not shown) here.

In this example, the A carrier 11 and the B carrier 12 have an A protrusion 15 and a B protrusion 16 formed in advance, and the protrusion 17 of the A protrusion 15 is fitted into the fitting hole 18 of the B protrusion 16. , and fixed with adhesive 19.

The protrusion 17 may be extended and welded on the outside. This is the case when the carrier is plastic, but when it is metal,
Connect A and B carriers together with rivets, bolts, etc.

There are mounting holes 20 around the outer shell internal gear 3 for fixing a device casing (not shown). ...... is the perforation.

FIG. 4 is an exploded enlarged sectional view of only the planetary gear 2.

The planetary gear 6 is a thin ring-shaped gear in the radial direction,
It meshes with the sun gear 1 and the outer shell gear 9, receives a force of f/2 from both, and transmits it to the planetary shaft 5 as a force of f.

The torque transmitted to the carrier 4 is thus carried by the planet gear 6, but no radial force is applied to the planet gear 6.

The ring 7 of the gear receiver has the same width W as the planetary gear 6, and is a buffering member disposed between the planetary shaft 5 and the planetary gear 6.

The pitch radius P is the sum of the thickness Q of the planetary gear, the thickness R of the ring 7 of the gear receiver, and the inner radius U of the gear passage hole 21 of the ring of the gear receiver.
It is.

Of course, an appropriate rear balance must be provided between the planetary gear and the gear receiver ring, and between the gear receiver ring and the planetary shaft.

The ring of the gear bridge can also be made of plastic.

The planetary disk 8 is a simple disk whose outer diameter is equal to the pitch diameter of the planetary gear.

A disc through hole 22 with an inner radius of ■ is bored in the center.

The planetary shaft 5 connects the planetary gear 6 via the ring 7 to the gear receiver.
Although the planetary disk 8 is directly supported, the planetary gear 6, the gear bearing ring 7, and the planetary disk 8 are not connected to each other and are independent, and rotate relative to each other with the free contact surface 23 as the boundary. I can do things.

The operation and effect of the above configuration will be explained.

This planetary gear device can be used as a speed reducer or a speed increaser by fixing the outer shell internal gear and connecting the input shaft and output shaft to the sun shaft-carrier shaft hole.

It is also possible to rotate the outer shell internal gear.

Since the planetary gear 6 and the planetary disk 8 are independently supported on the sun shaft 5, the planetary gear 6 transmits torque and the planetary disk 8 suppresses centrifugal force and radial deflection of the carrier. Functions are completely separated.

The planetary disk 8 and the outer shell ring 10 are in circumscribed contact to suppress the deflection of the carrier in the radial direction and prevent the tips of the planetary gear teeth from biting into the outer shell gear due to excessive pressure.

Therefore, power transmission efficiency is high, and there is little heat generation and vibration due to contact between gears.

Gear wear is also minimal. The shaft-disk friction force F3 applied between the planetary disk 8 and the planetary shaft 5 is small.

Since the gear 6 and the disc 8 are only lightly in contact with each other via the free contact surface 23, the normal force f caused by the torque T applied to the gear does not act between the disc and the shaft.

Equations (3) and (4) do not hold, and the disc/gear friction force F
2 is almost 0.

The shaft/disc friction force F3 is also smaller than the disc/outer shell ring friction force F1.

The disk can rotate freely, and F2. Since F3 is smaller than Fl, it rolls on the outer ring and rotates.

Therefore, there is almost no deviation in relative rotational speed between the disk and the planetary gear.

Moreover, since no thrust force acts between the disc and the planetary gear, even if there is a difference in rotational speed, this will not cause friction loss.

There is little heat generation and vibration, and the disk and gear side will not wear out even after many years of use.

FIG. 5 is a schematic diagram showing the distribution of forces among such a planetary gear, a planetary disk and a planetary shaft, a sun gear, and an outer shell internal gear.

The planetary gear 6 receives the force f/2 from the sun gear and the outer shell internal gear, and generates a frictional force F4 between it and the planetary shaft in the direction of the force.

The planetary disk 8 rotates while maintaining a substantially concentric position with the planetary shaft 5 without receiving any force from the gear.

The inner radius of the hole in the planetary disk (■) is made slightly smaller than the inner radius (U) of the ring of the gear holder, so the effect of the disk is more strongly reduced. The influence can be removed.

When these errors exist, the center of rotation of the carrier is out of alignment with the center of the external internal gear, and the former moves circularly around the latter at a small radius.

If the planetary disk 8°8 were not present, the meshing would not be balanced, resulting in localized deep meshing and shallow regions, resulting in large resistance.

Since the over-elevated discs 8, 8 are present, the locus of the rotation center of the gear is determined only by the discs 8, 8 and the outer shell ring 10.

Since U>V, even if the rotation locus of the planetary disk 8 is specified, the ring 7 of the gear receiver can be misaligned with respect to the planetary disk 8, and the misalignment of the mesh is caused by the misalignment of the center. The torque absorbed and applied to the planetary gears is always evenly distributed.

The planetary gear and gear receiver have separate rings and have clearance, so even if there is an error in carrier division, the torque is equalized.

In this way, it is a useful invention.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of a planetary gear device according to an embodiment of the present invention. Figure 2 is a partially cutaway rear view of the same item. FIG. 3 is an XOY sectional view in FIG. 1. Figure 4 is an exploded enlarged sectional view of only the planetary gear. FIG. 5 is a schematic diagram showing the force relationship of planetary gears in the configuration of the present invention. FIG. 6 is a sectional view of a known planetary gear device. FIG. 7 is a schematic diagram showing the force relationship of the planetary gears in the known device of FIG. 1...Sun gear, 2...Planetary gear, 3
......Outer shell internal gear, 4...Carrier,
5... Planetary shaft, 6... Planetary gear, 7.
... Gear holder is ring, 8 ... Planet disk,
9... Outer shell gear, 10... Outer shell ring, 21... Gear through hole, 22... Disc through hole, 23... ...Free contact surface, Fl...Frictional force between the planetary disk and outer shell ring, F2...Frictional force between the planetary disk and the planetary gear, F3... Frictional force between the planetary disk and the planetary shaft, f...Normal force generated between the planetary gear and the planetary gear, T...Torque generated in the carrier, N... Number of planetary gears.

Claims (1)

[Claims] 1 A sun gear 1, an appropriate number of planetary gears 2 surrounding and meshing with the sun gear 1, an outer shell internal gear 3 surrounding and meshing with the planetary gear 2, and a planetary gear 2,... are connected to a planetary shaft 5 , . . . In a planetary gear device including a carrier 4 pivotally supported by
The planetary gear 2 includes a planetary gear 6 at the center outer periphery provided with teeth,
On the other hand, the gear holder at the center inner periphery that fits into the inner periphery with a clearance has the ring 7 and the planetary gear 6, and the gear holder is provided independently from the planetary gear 6 and the ring 7 on both sides of the ring 7. The outer shell internal gear 3 consists of a planetary disk 8 having an outer diameter equal to the pitch circle, and the outer shell internal gear 3 includes an outer shell gear 9 provided with teeth.
The outer shell ring 10 is provided on both sides of the outer shell gear 9 and has an inner diameter equal to the pitch circle. A planetary gear device characterized by being smaller than U.