Inscribed meshing planetary gear construction

In an inscribed meshing planetary gear construction provided with a carrier pin (a carrier member) 116, rigidity and stability are improved and its entire length is shortened, resulting in that in particular, the connection between an input shaft 101 and an eccentric body 103 can be improved so as to reduce the number of component parts and the number of assembling steps. In order to realize this object, a flange part 114 of an output shaft 102, a carrier pin 116 and a support ring 117 are supported at both ends by a pair of bearings 115a and 115b, and then a reduction gear mechanism is disposed between bearings 115a and 115b. The input shaft 101 is formed with a D-cut part of cross section by cutting a part of its outer circumference in parallel with its axial direction. This cut part is utilized so as to set a circumferential position (a stop of rotation) between the input shaft 101 and an eccentric body 103. A carrier pin 116 has a pipe-like spacer 125 at its central part, the axial position of the flange part 114, the carrier pin 116 and the support ring 117 is set through a spacer 125.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an inscribed meshing planetary gear construction 
which is preferably applied to a speed increasing gear or a reduction 
gear, more particularly, a small-sized speed increasing gear or a 
reduction gear in which a high output torque is required. 
2. Description of the Prior Art 
In the prior art, it is widely known to provide a speed increasing gear or 
a reduction gear employing an inscribed meshing planetary gear 
construction comprising a first shaft, an external-tooth gear mounted 
(assembled) on the first shaft through a eccentric body in a state where 
the external-tooth gear can be rotated eccentric around the first shaft, 
an internal-tooth gear with which the external-tooth gear is inscribed and 
meshed, and a second shaft connected to the external-tooth gear through 
means for transmitting only the rotation component of the external-tooth 
gear. 
An example of the prior art of this construction is shown in FIGS. 14 and 
15. This prior art is constructed such that said first shaft is applied as 
an input shaft, said second shaft is applied as an output shaft and at the 
same time said construction is applied to a reduction gear by fixing the 
internal-tooth gear. 
Eccentric bodies 3a, 3b are fitted to the input shaft 1 with a 
predetermined phase difference (180.degree. in this example). The 
eccentric bodies 3a, 3b are integrated into one body. Two external-tooth 
gears 5a, 5b are placed on to each of these eccentric bodies 3a, 3b 
through eccentric bearings 4a, 4b. A plurality of inner roller holes 6 are 
provided in the external-tooth gears 5a, 5b and then an inner pin 7 and an 
inner roller 8 are fitted in these roller holes. 
A main object of providing two external-tooth gears (in plural rows) is to 
increase a transmittance capacity, maintain a strength and keep a 
rotational balance. 
External teeth 9 such as trochoidal teeth or circular teeth etc. are 
provided at outer circumferences of said external-tooth gears 5a, 5b. The 
outer teeth 9 are inscribed and meshed with the internal-tooth gear 10 
fixed to a casing 12. The internal teeth of the internal-tooth gear 10 are 
constructed such that an outer pin 11 is loosely fitted to an inner pin 
hole 13 and held to be easily rotatable. 
An inner pin 7 passing through said external-tooth gears 5a, 5b is tightly 
fitted to or fixed to a flange part 14 of the output shaft 2. 
When the input shaft 1 is rotated once, the eccentric bodies 3a, 3b is also 
rotated once. The external-tooth gears 5a, 5b are apt to oscillatebly 
rotate around the input shaft 1 through this one revolution of the 
eccentric bodies 3a and 3b. However, since the rotation is restricted by 
the internal-tooth gear 10, the external-tooth gears 5a, 5b almost merely 
perform oscillation while being inscribed with the internal-tooth gear 10. 
Now, it is assumed that the number of teeth of the external-tooth gears 5a, 
5b is N and the number of teeth of the internal-tooth gear 10 is N+1, then 
the difference between the numbers of teeth is 1. Consequently, the 
external-tooth gears 5a, 5b are displaced by one tooth relative to the 
internal-tooth gear 10 fixed to the casing 12 every time the input shaft 1 
is rotated. This means that one revolution of the input shaft 1 is 
decelerated to a revolution of -1/N of the internal-tooth gear. 
Oscillation component of the external-tooth gears 5a, 5b is absorbed by 
clearances between the inner roller holes 6 and the inner pins 7 and then 
only the rotational component is transmitted to the output shaft 2 through 
the inner pins 7. 
In this case, the inner roller holes 6a, 6b and the inner pins 7 (inner 
rollers 8) form an "isokinetic inscribed meshing mechanism". 
As a result, finally, a reduction of reduction ratio -1/N can be 
accomplished. 
In the example of this prior art, the internal-tooth gear of the inscribed 
meshing planetary gear construction is fixed, the first shaft is an input 
shaft and the second shaft is an output shaft. However, a reduction gear 
can also be constructed by fixing the second shaft and applying the first 
shaft as an input shaft and the internal-tooth gear as an output shaft. 
Furthermore, a speed increasing gear can also be constructed by reversing 
these inputs and outputs. 
As described above, the inner pin 7 has a function to form an circular 
tooth acting as one of elements of said isokinetic inscribed meshing 
mechanism constructed with the inner roller holes 6a, 6b, and also has 
another function acting as a carrier member for transmitting a rotational 
force of a rotation of external-tooth gears 5a, 5b to the output shaft 2. 
In particular, in order to keep a superior former function, it was 
essential to provide the inner rollers 8 capable of being freely rotated 
around the outer circumference of the inner pins 7. The inner roller 8 
shows a problem of expensive cost due to the fact that the material must 
be hard and both outer and inner circumferences thereof must be coaxially 
and accurately machined (processed or manufactured). 
In view of this fact, an idea has been proposed that the function which 
forms a circular tooth of one of the elements of the isokinetic inscribed 
meshing mechanism and another function which acts as a carrier member for 
transmitting a rotational force of the external-tooth gears 5a, 5b to the 
output shaft 2 are separated, and even if the inner roller 8 is 
eliminated, it has a similar performance to that of having the inner 
roller 8. 
This structure is illustrated in FIGS. 17 and 18. 
This structure comprises, as means for transmitting a rotational component 
of the external-tooth gears, the inner pin 7 capable of constructing the 
isokinetic inscribed meshing mechanism relative to the inner pin holes 
(corresponding to the inner roller holes) 19a, 19b arranged in the 
external-tooth gears 5a, 5b, an annular support ring 17 receiving a 
rotation corresponding to the rotational component of the inner pin 7 
(=the rotational component of the external-tooth gears), and a carrier pin 
16 projected from the flange part 14 formed at the output shaft 2, 
connected and fixed to the support ring 17. 
Said inner pin 7 is rotatably fitted to the flange part 14 and the support 
ring 17 through bushes 18a, 18b. That is, since the inner pin 7 is not 
necessarily tightly connected to the output shaft 2 due to the presence of 
the carrier pin 16, it can be constructed to be rotatable, resulting in 
that the prior art inner roller 8 can be eliminated: Said annular support 
ring 17 is assembled to an extremity end portion of said carrier pin 16. 
Since the carrier pin 16 only has a function to transmit a rotational 
force of the support ring 17 to the output shaft, there are provided big 
through-holes 20a, 20b which do not interfere with the carrier pin 16 even 
if the carrier pin 16 oscillates at the corresponding portion on the 
external-tooth gears 5a, 5b. 
Incidentally, in FIG. 17, reference numerals 15a, 15b denote bearings of 
the output shaft 2. Reference numeral 21 denotes an inner pin keep plate 
for determining an axial position of the inner pin 7. Reference numeral 23 
denotes an inner pin keep bolt. Reference numeral 22 denotes a steel plate 
race. 
Although the prior art illustrated in FIGS. 14, 15 and FIGS. 17, 18 is "an 
inscribed meshing planetary gear construction" having two external-tooth 
gears, it is apparent that more simple type having one external-tooth gear 
may also be presented. This example is illustrated in FIGS. 19 and 20. 
However, as the inscribed meshing planetary gear construction, it is quite 
similar to those illustrated in FIGS. 14, 15 and FIGS. 17, 18, so that 
similar locations are merely denoted by reference symbols having no 
suffixes a and b and their duplicate description will be eliminated. 
By the way, it is normal that a speed increasing gear or reduction gear 
having the aforesaid inscribed meshing planetary gear construction has a 
transmitting capacity of about 0.1-160 KW. When a transmitting capacity is 
lower than the former, it is normal that a parallel axis type gear 
reduction gear having a normal involute gear teeth is applied. Because, in 
this case, a part of the reduction gear mechanism can be made compact as 
compared with a size of a motor without depending on the inscribed meshing 
planetary gear construction (an outer diameter of the part of the 
reduction gear mechanism can easily be the same diameter in respect to an 
outer diameter of the motor). 
An example of a geared motor 40 is illustrated in FIGS. 22-24, which is 
integrally constructed with the motor using the well-known parallel axis 
gear reduction gear mechanism. FIG. 22 is a front elevational view, and 
FIG. 23 is a side elevational view as viewed from an installing surface 
42. FIG. 24 is a sectional view showing a gear reduction gear mechanism 
part 44 as a developed section. 
However, as apparent from FIGS. 14, 17 and 19, this prior art type 
reduction gear was constructed such that a variation of load generated at 
the reduction gear mechanism part or an external radial load from a mating 
mechanism acting against the output shaft 2 was supported by a pair of 
bearings 15a and 15b supporting output shaft 2, so that it is need in 
generally that a Y segment in each of the figures was elongated and an X 
segment was shortened as much as possible in order to increase a 
supporting stability. 
However, there was a problem that the X segment was hardly shortened and 
the Y segment was necessarily elongated, resulting in that the axial 
length of the reduction gear was elongated. 
In addition, in case of a structure shown in FIGS. 17 and 18, a carrier 
member 16 was integrally formed with the output shaft 2, resulting in that 
there was also a problem that the manufacturing was quite difficult, 
required a high cost and then an effect of cost reduction caused by 
elimination of inner rollers 8 was eliminated.. 
Furthermore, in order that the inner pins 7 were supported and free rotate, 
an inner pin pressing plate 21, a steel plate ring 22 and inner pin 
pressing bolts 23 and the like were essential, resulting in that there was 
also a problem that the number of component parts and the number of 
assembling steps were increased. 
On the other hand, in case of the structure shown in FIG. 21 in which the 
reduction gear shown in FIGS. 19 and 20 was fixed at its flange, the 
aforesaid problem was present as it was, and at the same time, since it 
had a double-flange structure in the casing 12 in which a distance Z 
between an installing flange 36 for the mating machine and a flange 37 for 
fixing an internal-tooth gear was elongated due to a requirement of the 
elongated Y segment, resulting in that, for example, when this structure 
was made by aluminum die-cast, or aluminum casting, the mold was 
complicated, the manufacturing was difficult and expensive. 
In addition, in this kind of prior art inscribed meshing planetary gear 
construction including the aforesaid prior example, a connection between 
the input shaft 1 and eccentric bodies 3 or 3a, 3b was carried out under a 
combination of a key 30 and key-ways 31 and 32 (refer to FIGS. 19 and 20), 
resulting in that there was a problem that the number of machining steps 
and the number of component parts were increased and the end mill 
machining was required, so that an efficiency of the manufacturing was 
poor and a mass productivity was low. 
In addition, there was a problem that a concentration of stress could 
easily be generated at the key-ways 31 and 32. Due to this fact, there was 
a requirement that the diameter of the input shaft 1 be made large as much 
as possible. However, there was a substantial restriction on an expansion 
of an outer diameter of the eccentric body in order to realize a compact 
characteristic of a speed increasing gear or reduction gear in the 
diametrical direction, and further there was a limitation in increasing in 
a diameter of the input shaft due to a requirement of assuring a wall 
thickness of the key-way 32. 
By the way, as a method for position setting in the circumferential 
direction (stopping of rotation) of substantial coaxial two members, it is 
known as a general well-known technology in which a part of an outer 
circumference of an inner member is cut in parallel with an axial 
direction to form a cut part having about a D-shaped cross section, and 
this cut part is utilized to set a position of circumferential direction 
between the inner member. 
However, in the case where such a structure as above is employed as a 
circumferential position setting structure between the input shaft 1 and 
the eccentric bodies 3, 3a and 3b of this kind of inscribed meshing 
planetary gear construction, a bearing 35 (in general, a ball bearing is 
utilized in view of a cost) at the output shaft must be necessarily a 
bearing of small diameter in which it inscribes against a flat surface of 
the cut part, it may not be allowed in view of its strength. As regards 
this matter, it may also be proposed that an inner diameter of the bearing 
35 has the same diameter as that of the input shaft 1 and a filling 
material is enclosed at the cut part. However, this structure was not 
appropriate as a bearing structure for the input shaft 1 to which a force 
of radial direction was always applied due to an eccentric rotation of the 
external-tooth gear or bending of the output shaft. 
That is, it was a practical situation in the prior art that this "method of 
cutting a part of an outer circumference of the input shaft in parallel 
with its axial direction" was hardly employed as a structure to be applied 
to this kind of inscribed meshing planetary gear construction. 
The small sized geared motor using the parallel axis gears shown in FIGS. 
22 and 24 was hardly used due to the fact that it could not get a high 
output torque and it was difficult in view of its structure that the motor 
(the input shaft 1) and the output shaft 2 were concentrically arranged as 
shown in FIG. 24. 
There was a problem that a centering location and a fixing of the motor 
were hard due to the fact that the motor (the input shaft 1) and the 
output shaft 2 were not concentric and no fitting parts concentric with 
the output shaft 3 was prepared at the reduction gear mechanism. 
The present first invention has been constructed in view of the aforesaid 
various problems of the prior art and it is an object of the present 
invention to provide an inscribed meshing planetary gear construction 
comprising; 
the first shaft, an external-tooth gear placed on an eccentric axis on the 
first shaft through an eccentric body attached to the first shaft, an 
internal-tooth gear with which the external-tooth gear is inscribed and 
meshed, and the second shaft connected to the external-tooth gear through 
means for transmitting only a rotational (tangential) component of the 
external-tooth gear, wherein as means for said transmitting the rotational 
component, there are provided inner pins capable of forming an isokinetic 
inscribed meshing mechanism in respect to inner pin holes disposed in the 
external-tooth gear, an annular support ring for receiving a rotation 
corresponding to the rotational component of the external-tooth gear 
through the inner pins, and a carrier member projected from a flange part 
formed in the second shaft, connected and fixed to the support ring. 
In the above construction, the annular support ring and the flange part of 
the second shaft are disposed while holding the external-tooth gear 
therebetween, and both the support ring and the flange part are supported 
at both ends to a casing through a pair of bearings. The carrier member is 
separated from the support ring and the flange part and formed in a 
substantial column-like shape. A pipe-like spacer is press fitted in 
advance at a center position of the carrier member. Both ends of the 
carrier member are press fitted to the support ring and the flange part. 
And axial position of the support ring, the carrier member and the flange 
part is set through the spacer. 
Said inner pins may be freely fitted to the support ring and flange part. 
Further, it is an object of the present second invention to overcome the 
aforesaid problem by arranging an inscribed meshing planetary gear 
construction comprising; 
the first shaft, an external-tooth gear placed on an eccentric axis on the 
first shaft through an eccentric body attached to the first shaft, an 
internal-tooth gear with which the external-tooth gear is inscribed and 
meshed, and the second shaft connected to the external-tooth gear through 
means for said transmitting only a rotational component of the 
external-tooth gear, wherein as means for transmitting said rotational 
component, there are provided inner pins capable of forming an isokinetic 
inscribed meshing mechanism in respect to inner pin holes placed in the 
external-tooth gear, an annular support ring for receiving a rotation 
corresponding to the rotational component of the external-tooth gear 
through the inner pins, and a carrier member projected from a flange part 
formed in the second shaft, connected and fixed to the support ring. 
In the above construction, the annular support ring and the flange part of 
the second shaft are attached while holding the external-tooth gear 
therebetween, and both the support ring and the flange part are supported 
at both ends to a casing through a pair of bearings. The carrier member is 
separated from the support ring and the flange part and formed in a 
substantial column-like shape. A pipe-like spacer is press fitted in 
advance at a center position of the carrier member. Both ends of the 
carrier member are freely fitted to the support ring and the flange part. 
Axial position of the support ring, carrier member and flange part is set 
by holding the flange part, spacer and support ring by means of a stopper 
ring means attached at one end of the carrier member and a screw-nut means 
attached at the other end of the carrier member. 
Said inner pins may be loosely fitted to the support ring and flange part, 
their axial position is set by either the inner rings or outer rings of 
the pair of bearings. 
It is an object of the present third invention to overcome the aforesaid 
problem by arranging an inscribed meshing planetary gear construction 
comprising; the first shaft, an external-tooth gear placed on an eccentric 
axis on the first shaft through an eccentric body attached to the first 
shaft, an internal-tooth gear with which the external-tooth gear is 
inscribed and meshed, and the second shaft connected to the external-tooth 
gear through means for transmitting only a rotational component of the 
external-tooth gear, wherein as means for said transmitting the rotational 
component, there are provided inner pins capable of forming an isokinetic 
inscribed meshing mechanism in respect to inner pin holes disposed in the 
external-tooth gear, an annular support ring for receiving a rotation 
corresponding to the rotational component of the external-tooth gear 
through the inner pins, and a carrier member projected from the flange 
part formed in a second shaft, connected and fixed to the support ring. 
In the above construction, the annular support ring and the flange part of 
the second shaft are connected while holding the external-tooth gear 
therebetween, and both the support ring and the flange part are supported 
at both ends to a casing through a pair of bearings. A part of an outer 
circumference of the first shaft is cut in parallel with its axial 
direction to form a cut part having the cross sectional shape of about 
D-shape, and this cut part is utilized to define a positioning in the 
circumferential direction of each of the first shaft and the eccentric 
body. 
In this case, an inner diameter of the bearing of the first shaft facing to 
the second shaft may be set to be slightly smaller than an outer diameter 
of the first shaft, and then a filling material is enclosed at a slight 
remained cut part. 
It is an object of the present fourth invention to overcome the aforesaid 
problem by arranging an inscribed meshing planetary gear construction 
comprising a first shaft, an external-tooth gear placed on an eccentric 
axis on the first shaft through an eccentric body attached to the first 
shaft, an internal-tooth gear with which the external-tooth gear is 
inscribed and meshed, and a second shaft connected to the external-tooth 
gear through means for transmitting only a rotational component of the 
external-tooth gear, wherein as means for said transmitting the rotational 
component. There are provided inner pins capable of forming an isokinetic 
inscribed meshing mechanism in respect to inner pin holes disposed in the 
external-tooth gear, an annular support ring for receiving a rotation 
corresponding to the rotational component of the external-tooth gear 
through the inner pins, and a carrier member projected from a flange part 
formed on the second shaft, connected to and fixed to the support ring. 
In the above construction,the annular support ring and the flange part of 
the second shaft are attached while holding the external-tooth gear 
therebetween, and both the support ring and the flange part are supported 
at both ends at a casing through a pair of bearings. A square-shaped 
installing flange and a circular part for centering location are formed in 
the second shaft side of the casing in concentric with the second shaft 
and in concentric with the first shaft. And installing bolt holes are 
placed near a top point of the square-shaped installing flange. 
In the present first to fourth inventions, the carrier member is passed 
through the external-tooth gear and attached hold the external-tooth gear 
with the annular support ring and the flange part of the second shaft, and 
both the support ring and the flange part are supported at both ends at a 
casing through a pair of bearings. As a result, it is possible to 
remarkably improve rigidity and stability of a reduction gear mechanism. 
In the present first invention, as a structure for connecting and position 
setting the flange part, carrier member and support ring, the carrier 
member is separated from the support ring and the flange part and 
substantially formed into a column shape, and at the same time, a 
pipe-like spacer is press fitted in advance at a center position of the 
carrier member, thereafter both ends are press fitted to the support ring 
and flange part, so that an axial position of the support ring, carrier 
member and flange part is set through the spacer. 
As a result, it is not necessary to make an integral projection of the 
carrier member from the flange part as found in the prior art, and not 
necessary to manufacture a complex structural member ranging from the 
flange part to the carrier member, and thus a cost can be substantially 
reduced. In addition, since the carrier itself is a structure in which a 
pipe-like spacer is fitted into a simple column-like shape; resulting in 
that the manufacturing is quite easy, and at the same time the strength 
and accuracy may become superior. 
That is, if the carrier member itself is formed to have a stage which is 
found in a coupling structure between the support ring and the carrier 
member as found in the prior art, the manufacturing is difficult and the 
accuracy is hardly attained. Furthermore, a stress may easily be 
concentrated at a part indicated by a reference symbol P1 in FIG. 16. In 
addition, in order to eliminate this problem, it is necessary to make a 
round R at the part of said P1, and in this case, it is necessary to make 
a chamfer corresponding to the side of the support ring. However, since it 
is necessary to make a chamfer at a part of a stage indicated by a 
reference symbol P2, only a range L1 can contribute to an axial position 
setting. Therefore, in order to keep this range L1 as long as possible, it 
is necessary to increase a large diameter D1 or to decrease a small 
diameter D2, resulting in that there is a problem that the weight is 
increased or the strength is decreased. 
To the contrary, the present first and second inventions are constructed in 
such a manner that a pipe-like spacer is merely fitted to a column-like 
carrier member, so that a concentration of stress is hardly produced, an 
entire thickness of the pipe can be utilized to set an axial position, and 
further an entire length (an axial length) of many the pipes can be easily 
arranged. And then, axial positions of a plurality of carrier members can 
easily be set. 
Constitution described in the present first invention aims at an 
application to a so-called maintenance free small-sized speed increasing 
gear or reduction gear under an assumption that it is not frequently 
decomposed after once assembled. 
Accordingly, the carrier member, flange part and support ring are connected 
by the most simple press-fitting so as to realize a low cost. 
In this case, the structure can be simplified by press fitting the inner 
pins also into the flange and the support ring, resulting in that a more 
low cost can be attained. 
On the other hand, construction described in the present second invention 
aims at an maintenance or repairing through the decomposition. 
Accordingly, it has a structure in which the flange part, a spacer for the 
carrier member and the support ring are held and fixed by the stopper ring 
means and the screw-nut means. The reason why the stopper ring means is 
employed consists in the fact that a stress is concentrated at the stage 
part if the carrier member having a stage part is employed, and that the 
staged member can not be machined by a so-called coreless grinding plate. 
Therefore, the cost is expensive and a high accurate machining can not be 
carried out. 
In this case, in view of the decomposition, if inner pins are freely fitted 
to the flange part and the support ring, and an axial position is set by a 
pair of bearings holding the flange part and the support ring, the 
structure can be simplified and the inner pins can be freely rotated. 
In the present third invention, similar to the present first and second 
inventions, a carrier member passes through the external-tooth gear and is 
disposed so that the external-tooth gear is held by the annular support 
ring and the flange part of the second shaft, and further both the support 
ring and the flanger part are supported at both ends at a casing through a 
pair of bearings. As a result, rigidity of the reduction gear mechanism, 
in particular, rigidity and stability in respect of the radial direction 
can be improved. 
Due to employment of this construction, it becomes possible to make an 
inner diameter of the bearing of the second shaft smaller, and a part of 
an outer circumference can be cut in parallel with an axial direction of 
the first shaft to enable D-shaped cut part. 
By forming the same shape hole including the cut part in the eccentric 
body, a position setting in the circumferential direction (stopping of 
rotation) can be obtained. 
Since the structure for preventing the rotation can be employed, the cut 
part line between the first shaft and the eccentric body are changed from 
an acute angle (prior art) to an obtuse angle (third invention) so that a 
concentration of stress hardly occurs. Also, since a key which restricts a 
minimum thickness of the eccentric body is not present, it becomes 
possible to increase a diameter of the first shaft and at the same time it 
becomes possible to decrease an outer diameter of the eccentric body. 
Therefore, the load capacity can be increased or a more small sized 
eccentric body can be used in response to the application. 
In the prior art, since the machining of key-way in the first shaft had to 
be cut by an end mill whereby a machining efficiency was quite inferior 
and a mass productivity was poor. However, in the case where a D-shaped 
cut part is formed, after many input shafts are arranged, and then the cut 
part is formed by a broach machining whereby the machining efficiency can 
be remarkably improved and the mass productivity is further improved. As a 
result, a further cost-reduction can be attained. 
Also, the number of component parts can be naturally decreased in 
correspondence with no presence of key, so that the number of assembling 
operations can be reduced. 
Although there is no special problem even if an inner diameter of the 
bearing of the first shaft facing to the second shaft is completely 
smaller diameter than that of a flat surface of the cut part due to said 
both supporting structures, it may be slightly lower set than that of an 
outer diameter of the first shaft (to a degree in which the cut part is 
slightly remained) and a filling material may be filled in the cut part 
slightly remained. 
With such an arrangement, it becomes possible to present a reduction in 
strength of the bearing at the second shaft from increasing. 
As a filling material, either resin or solder or the like can be applied. 
Lastly, in the fourth present inventions, similar to the present first to 
third inventions, basically employed an inscribed meshing planetary gear 
construction, not so-called parallel axis gear structure, and then the 
carrier member passes through the external-tooth gear so that the 
external-tooth gear is held by the annular support ring and the flange 
part of the second shaft, and both the support ring and the flange part 
are supported at both ends at a casing through a pair of bearings. As a 
result, rigidity of the reduction gear mechanism, in particular, rigidity 
and stability against a radial direction can be remarkably improved. In 
addition, the flange for fixing the internal-tooth gear and the flange for 
installing to the mating machine can be integrally formed whereby the 
machining can be easily attained, the low cost and reduction in the axial 
direction size can be realized. 
Furthermore, in the present fourth invention, the casing facing to the 
second shaft is formed with a square-shaped installing flange part as 
means for fixing to the mating machine, and installing bolt holes are 
disposed near a top part of the square-shaped installing flange. As a 
result, due to the both ends supporting structure, double-flange structure 
can be avoided, and at the same time a structure of the casing at the 
second shaft can be made quite simple, and then a smaller size and a lower 
cost than the prior art can be realized. 
In addition, since this installing flange part has a square shape, "a seat 
setting" as a simple reduction gear machine under a state before being 
fixed to the mating machine is superior, and it may not roll, resulting in 
that it has an advantage that it may easily be handled. 
With such a construction described above, the present invention may provide 
a small-sized device, high output and further the first shaft and the 
second shaft (in general, the input shaft and the output shaft) can be 
concentrically made, resulting in that a centering and a fixing to the 
mating machine could easily be carried out under a presence of a fitting 
part formed in concentric with the second shaft. 
In this way, according to the present invention (first to the fourth 
inventions), since the reduction gear mechanism is supported at both ends 
by a pair of bearings, and an entire length of the reduction gear machine 
can be shortened, and its structure is quite simple and it can be 
assembled with high accuracy while it has a construction comprising a 
support ring and a carrier member. In addition, an assembling structure of 
each of the inner pins is quite simple, so that entirely the high accuracy 
and a low cost can be obtain. As a result, a connecting structure between 
the first shaft and an eccentric body can be rationally improved, 
resulting in that entirely a high strength and a low cost can be obtained. 
In addition, employing this construction eliminates a double flange of the 
casing at the second shaft side so that the manufacturing of the casing at 
the output part can easily be performed in a low cost. In addition, 
although the first shaft, the second shaft, fitted part around the second 
shaft and installing bolt holes are concentrically arranged, so that 
centering and fixing of them to the mating machine can be quite easily be 
performed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, some preferred embodiments of the present 
invention will be described in detail. 
FIG. 1 is a sectional view showing a reduction gear to which an inscribed 
meshing planetary gear construction of the present first invention is 
applied, and FIG. 2 is a sectional view taken along a line II--II of FIG. 
1. 
In the following description, the same or similar parts as or to those of 
the construction of the well-known example already described are denoted 
by the same latter two-digit numbers. 
One end of each of carrier pins (carrier members) 116 which is separated 
from the flange part 114 is fitted (press fitted) to the flange part 114 
of the output shaft 102. The support ring 117 is fitted (press fitted) to 
the other end of the carrier pin 116, and then "a carrier" is constructed 
by the support ring 117 and the carrier pin 116. 
The flange part 114, the carrier pins 116 and the support ring 117 are 
supported at both ends at the casing 112 by the pair of bearings 115a and 
115b. 
The pipe-like spacer 125 is fitted (press fitted) at a central part of the 
carrier pin 116. Accordingly, even if there is a slight difference in a 
fitting depth of the carrier pin 116 into the support ring 117 or into the 
flange part 114, a distance between the support ring 117 and the flange 
part 114 is always kept constant under a function of this spacer 125 
without failing, and further the same distance can be assured at portions 
of all (4) carrier pins 116. 
The external-tooth gears 105a and 105b are formed with carrier pin holes 
(through-holes) 120 through which the carrier pins 116 are passed. Size of 
each of the carrier pin holes 120 is set in such a manner that the carrier 
pins 116 are not contacted with the external-tooth gears 105a and 105b 
even if the external-tooth gears 105a and 105b are oscillated. 
The inner pins 107 are press fitted to the support ring 117 and the flange 
part 114. Accordingly, their free rotation can not be performed. However, 
due to the facts that 
1) since each of the inner pins is a simple column-like shape, a mirror 
surface finishing can be easily (at a low cost) with a hard raw material; 
2) since a reduction gear mechanism is held by the pair of bearings 115a 
and 115b, an entire rigidity can be quite improved and inner pins 107 can 
be supported under a quite stable state; and 
3) since a construction in which the inner pins 107 and the carrier pins 
116 are separated, a radial load applied from the output shaft or the like 
is received by the carrier pins 116, no strong radial load is applied to 
the inner pins 107, so that they can be supported in a more stable 
condition; even if the inner rollers are practically eliminated and the 
inner pins 107 can not rotate, there is no problem at all. However, the 
inner pins 107 is not necessary to be press fitted, it may be freely 
fitted. 
Action of this preferred embodiment will be described as follows. 
It is quite similar action to that of the prior art well-known example that 
the external-tooth gears 105a and 105b are oscillatably rotated together 
with a rotation of the input shaft 101, and the rotation of input shaft 
101 becomes a reduced rotation (rotational) of the external-tooth gears 
105a and 105b according to an engagement (meshing) between the outer pins 
111 corresponding to the inner teeth of the internal-tooth gear 110 and 
the external-tooth gears 105a and 105b. 
Rotation of the external-tooth gears 105a and 105b is absorbed at their 
oscillating components by clearances between the inner pin holes 119 and 
the inner pins 107, and only a rotational component is transmitted to the 
flange part 114 of the output shaft 102 and the support ring 117 through 
the inner pins 107. The rotational force transmitted to the support ring 
117 is transmitted to the output shaft 102 through the carrier pin 116. 
Since the external radial load acting against the output shaft 102 is 
received at both ends by the bearing 115a, and by the bearing 115b through 
the carrier pins 116 and the support ring 117, the external radial load 
does not influence against the inner pins 107. 
According to this preferred embodiment, since the reduction gear mechanism 
is supported at both ends by a pair of bearings 115a and 115b, it may 
provide some effects that a quite high rigidity can be attained, a 
connection among the flange part 114, the carrier pins 116 and the support 
ring 117 can be performed quite simply and at a high accuracy, the inner 
rollers in the inner pins 107 may also be eliminated to attain a low cost. 
Then, FIGS. 3 and 4 show a preferred embodiment (the second invention) 
under an assumption that frequent decomposition and assembling operation 
are carried out. In this preferred embodiment, a stopper ring 224 is 
disposed at one end of the carrier pin 216, a threaded part 227 is 
disposed at the other end of the carrier pin. A flange part 214, a spacer 
225 and a support ring 217 are strongly held by the stopper ring 224 and a 
nut 228 threadably engaged with the threaded part 227 to assemble them. 
Accordingly, their decomposition and assembling can be carried out at any 
number of times. 
In addition, the carrier pin 216 is not a so-called staged bolt, but the 
stopper ring 224, so that it is possible to prevent any concentration of 
stress at this staged part. In the case where the staged carrier pin is 
employed, a so-called core-less grinder may not be applied for its 
machining operation, so that the high cost and a low accuracy may not be 
avoided. However, in this preferred embodiment, since the stopper pin 224 
is employed, the machining with a core-less grinder can be utilized, and 
then a low cost and a high accuracy can be realized. 
Incidentally, in this preferred embodiment, inner pins 207 are freely 
fitted in the inner pin holding holes 226a and 226b at the flange part 214 
of the output shaft 202 and the support ring 217. Due to this fact, it can 
be freely rotated, thereby a sliding generated between the inner pin holes 
219a, 219b and the inner pins 207 may well be absorbed. Decomposition at 
this time may also be carried out. 
Since the inner pins 207 are freely supported at both ends, elastic 
deformation may easily be generated when they receive a load from inner 
pin holes 219a and 219b, thereby an error caused by machining and 
assembling, or decomposition and reassembling may well be absorbed. In 
addition, even if the inner pins 207 are elastically deformed, rigidity of 
an entire reduction gear is not assured by the inner pins 207, but by the 
flange part 214, the carrier pins 216 and the support ring 217 supported 
at both ends by the casing 212, resulting in that a quite stable operation 
can be continued. 
Although the inner pins 207 are freely supported at both ends, their axial 
positions are set by outer rings 225a and 225b of the bearings 215a and 
215b, so that the inner pins 207 are not pulled out. 
Since other constructions are substantially similar to that of aforesaid 
prior art or aforesaid preferred embodiment, the repeat description will 
be eliminated by using the same latter two-digit numbers in the figures. 
Next, FIG. 5 is a sectional view showing a reduction gear to which an 
inscribed meshing planetary gear construction of the present third 
invention is applied, and FIG. 6 is a sectional view taken along a line 
VI--VI of FIG. 5. 
One end of each of carrier pins (carrier members) 316 which is separated 
from the flange part 314 is fitted (press fitted) to the flange part 314 
of the output shaft 302. The support ring 317 is fitted (press fitted) to 
the other end of the carrier pin 316, and then "the carrier" is 
constructed by the support ring 317 and the carrier pin 316. 
The flange part 314, the carrier pins 316 and the support ring 317 are 
supported at both ends at the casing 312 by the pair of bearings 315a and 
315b. 
The pipe-like spacer 325 is fitted (press fitted) at a central part of the 
carrier pin 316. Accordingly, even if there is a slight difference in a 
fitting depth of the carrier pin 316 into the support ring 317 or into the 
flange part 314, a distance between the support ring 317 and the flange 
part 314 is always kept constant under a function of this spacer 325 
without failing, and further the same distance can be assured at portions 
of all (4) carrier pins 316. 
As shown in FIGS. 7 and 8, a part of an outer circumference of the input 
shaft 301 is cut in parallel with an axial direction, and then a cut part 
340 having a about D-shaped form of cross section is made. The eccentric 
body 303 is provided with holes 341 having the same shape as that of a 
cross sectional shape of the input shaft 301 including a shape of the cut 
part 340, and then a position of setting in an axial direction (a stopper 
of rotation) between the input shaft 301 and the eccentric body 303 is 
defined under the fitting of the holes 341 (FIG. 8). 
A relation between an eccentric direction of the eccentric body 303 and a 
position of the cut part, it may be defined in reference to a strength and 
a common utilization (in particular, in the case where many external-tooth 
gears are employed in a reduction gear). 
An inner diameter of a bearing 335 of the input shaft 301 at the output 
shaft side is formed slightly smaller than an outer diameter of the input 
shaft 301 and then a filling material 336 such as resin or solder or the 
like is enclosed in the remained cut part (a part hatched in FIG. 9). This 
aims at keeping an inner diameter of the bearing 335 at the output shaft 
side as large as possible and aims at an avoidance of reduction of 
strength under a presence of the cut part as well as aims at a restriction 
of immersion of dusts or iron powder into this part. 
The inner pins 307 are press fitted to the support ring 317 and the flange 
part 314. Accordingly, their free rotation can not be performed. However, 
due to the facts that 
1) each of the inner pins is a simple column-like shape, and a mirror 
surface finishing can be easily (at a low cost) with a hard raw material; 
2) a reduction gear mechanism is held by the pair of bearings 315a and 315b 
so as to support it at both ends, and then an entire rigidity can be quite 
improved and inner pins 307 can be supported under a quite stable state; 
and 
3) a construction in which the inner pins 307 and the carrier pins 316 are 
separated, a radial load applied from the output shaft or the like is 
received by the carrier pins 316, no strong radial load is applied to the 
inner pins 307, so that they can be supported in a more stable condition; 
even if the inner rollers are practically eliminated and the inner pins 
307 can not rotate, there is no problem at all. However, the inner pins 
307 are not necessary to be press fitted, but may be freely fitted. 
Action of this preferred embodiment will be described as follows. 
First it is quite similar action to that of the described example that the 
external-tooth gear 305 is oscillatably rotated together with a rotation 
of the input shaft 301, and the rotation of input shaft 301 becomes a 
reduced rotation of the external-tooth gears 305 according to an 
engagement (meshing) between the outer pins 311 corresponding to the inner 
teeth of the internal-tooth gear 310 and the external-tooth gear 305a. 
Next, rotation of the external-tooth gear 305 is absorbed at their 
oscillating components by clearances between the inner pin holes 319 and 
the inner pins 307, and only a rotational component is transmitted to the 
flange part 314 of the output shaft 302 and the support ring 317 through 
the inner pins 307. The rotational force transmitted to the support ring 
317 is transmitted to the output shaft 302 through the carrier pin 316. 
Since the external radial load acting against the output shaft 302 is 
received at both ends by the bearing 315a, and by the bearing 315b through 
the carrier pins 316 and the support ring 317, the external radial load 
may not influence against the inner pins 307. This action is quite the 
same as those of the aforesaid present first and second inventions. 
In addition, since vibration of the flange part 314 and the support ring 
317 in the radial direction is almost eliminated, external radial load 
acting against the input shaft 301 is also decreased, resulting in that a 
load in strength around bearings 335 and 336 of the input shaft 301, in 
particular, around a bearing 335 at the output shaft side is reduced and 
then the input shaft 301 at this part can be made a small diameter, that 
is, the bearing 335 can be made small. As a result, it became possible to 
employ the technique that a part of an outer circumference of the input 
shaft 301 is cut in parallel with its axial direction. This cut part is 
utilized to set a circumferential position between the input shaft 301 and 
the eccentric body 303. Advantage provided by the position setting 
structure has already been described in detail. 
The present third invention can be necessarily applied to the system having 
two external-tooth gears. Actually, the present third invention is applied 
to the preferred embodiment of the aforesaid present first and second 
inventions as well as the fourth preferred embodiment to be described 
later. It should be noted that the circumferential position between the 
input shaft and the eccentric body is set by the structure having a 
D-shaped cross section. 
Finally, the preferred embodiment of the present fourth invention will be 
described in detail. 
FIG. 10 is a sectional view (taken along a line X--X of FIG. 11) of the 
reduction gear to which an inscribed meshing planetary gear construction 
of the present fourth invention is applied. FIG. 11 is an enlarged front 
elevational view taken from a mating machine. At an upper right half part 
of FIG. 11 is illustrated a sectional view showing a casing or the like 
along a line XI--XI of FIG. 10. FIG. 12 is an enlarged sectional view 
taken along a line XII--XII of FIG. 10. FIG. 13 is a partial sectional 
view taken along a line XIII--XIII of FIG. 11. In each of the figures, 
positions of the inner pins 407 and the carrier pin 416 are not accurate 
positions on the sectional line. 
One end of the carrier pin (carrier member) 416 separated from the flange 
part 414 is fitted (press fitted) to the flange part 414 of the output 
shaft 402. The support ring 417 is fitted (press fitted) to the other end 
of the carrier pin 416 and "the carrier" is constructed by the support 
ring 417 and the carrier pins 416. 
The flange part 414, carrier pins 416 and support ring 417 are supported at 
both ends at a casing 412 (practically, a casing 412a at the input shaft 
side and a casing 412b at the output shaft side) by a pair of bearings 
415a and 415b. 
A pipe-like spacer 425 is fitted (press fitted) at a central part of the 
carrier pin 416. Accordingly, even if there is a slight difference in a 
fitting depth of the carrier pin 416 into the support ring 417 or the 
flange part 414, a distance between the support ring 417 and the flange 
part 414 is always kept constant under a function of the spacer 425, and 
then the same distance may easily be kept at the portions of all four 
carrier pins 416. 
As shown in FIGS. 10 and 12, a part of an outer circumference of the input 
shaft 401 is cut in parallel with the axial direction, and is formed with 
the cut part 440 having a D-shaped cross section. The eccentric body 403 
is provided with holes 441 having the same cross sectional shape as that 
of the input shaft 401 including a shape of the cut part 440 and then a 
position setting in a circumferential direction (a stopper of rotation) 
between the input shaft 401 and the eccentric body 403 is carried out 
through the D-shape fitting of the holes 441. 
The inner pins 407 are press fitted to the support ring 417 and the flange 
part 414. Accordingly, their free rotation can not be attained. However, 
since this system is constructed in such a manner that 
1) since a shape of each of the inner pins 407 is a simple column, a high 
accurate machining may easily be carried out with a hard raw material; 
2) since it employs a structure in which a reduction gear mechanism is held 
and supported by a pair of bearings 415a and 415b, it is possible to 
substantially increase rigidity of an entire reduction gear, and the inner 
pins 407 can be supported under a quite stable state; and 
3) since the system has a construction in which it is separated into the 
inner pins 407 and the carrier pin 416, a radial load coming from the 
output shaft or the like is received by the carrier pins 416, resulting in 
that there is no opportunity that a strong radial load is applied to the 
inner pins 407; 
whereby there is no special problem even if inner rollers are practically 
eliminated and inner pins 407 can not rotate. 
It is also possible that the inner pins 407 are not "press fitted", but 
"freely fitted". In this case, a position setting in an axial direction of 
the inner pins 407 may be carried out by a pair of bearings 415a and 415b. 
As described above, the casing 412 is divided into a part 412a at the input 
shaft side and another part 412b at the output shaft side, and then the 
internal-tooth gear 410 is held by both casings 412a and 412b. 
The casing 412b and the internal-tooth gear 410 at the output shaft side 
are formed to have an entire cross sectional with shape of square. 
Installing bolt holes 439 for the mating machine are formed at a top point 
of the square at the casing 412b of the second shaft side, and then a 
concave part 445 is formed axially around the installing bolt holes 439 
(with the part of the installing flange 436 being left ). This concave 
part 445 is extended up to the internal-tooth gear 410 as it is and then 
an assembling of installing bolts (not shown) may easily be carried out. 
That is, in other words, an installing flange 436 is formed by a part F at 
which is not formed in the concave part 445 of casing 412b at the output 
shaft side. 
Connection and fixing of the casing 412a at the input shaft side, 
internal-tooth gear 410 and the casing 412b at the output shaft side are 
carried out by screwing bolts 450 from the casing 412b at the output shaft 
side. The reduction gear mechanism is supported at both ends by a pair of 
bearings 415a and 415b, and there is no part corresponding to a region Y 
as found in the prior art, resulting in that the casing 412b at the output 
shaft side is not necessarily to have a double flange structure, whereby 
an axial shortening of the part corresponding to a clearance Z (refer to 
FIG. 7) of the two flanges is attained, and a shape of the casing 412b at 
the output shaft side can be quite simplified. Therefore, for example, 
when it is manufactured by aluminum die-cast or aluminum castings, a 
combination of only two molds enables an easy and low cost manufacturing. 
In turn, a central location part 438 is concentrically formed around the 
output shaft 402. The output shaft 402 is concentrically formed with the 
input shaft 401 due to features of the inscribed meshing planetary gear 
construction being applied. Therefore the central location part 438 is 
concentric with the output shaft 402 as well as with the input shaft 401, 
and in addition, the four installing bolt holes 439 of the installing 
flange 436 are also concentric to each other. Therefore, centering and 
installing of it to the mating machine may quite easily be carried out and 
the fixing can be performed in a minimum space. 
Action of this preferred embodiment will be described. 
It is quite the same action as that of the prior art well-known example 
that the external-tooth gear 405 is oscillatably rotated together with a 
rotation of the input shaft 401 and a rotation of the input shaft 401 
becomes a reduced rotation (a self rotation) of the external-tooth gear 
405 under an engagement (meshing) between the external pins 411 
corresponding to the inner pins of the internal-tooth gear 410 and the 
external-tooth gear 405. 
Oscillating component of the rotation of the external-tooth gear 405 is 
absorbed by clearances between the inner pin holes 419 (corresponding to 
the inner roller holes) and the inner pins 407, only the rotational 
component is transmitted to the flange part 414 of the output shaft 402 
and the support ring 417. Rotational force transmitted to the support ring 
417 is transmitted to the output shaft 402 through the carrier pin 416. 
Since the external radial load acting against the output shaft 402 is 
received at its both ends by the bearing 415b, and by the bearing 415a 
through the carrier pins 416 and the support ring 417, no influence of the 
external radial load is applied to the inner pins 407. This action is 
quite the same as those of the present first to the third inventions. 
As a result, a load of the inner pins 407 is quite reduced, and a shape of 
the inner pins 407 can be quite simplified, resulting in that a high 
accurate machining may easily be realized with a hard raw material, and 
then a superior "isokinetic inscribed meshing mechanism" can be 
constructed without any inner rollers. Since there are carrier pins 416, 
the inner pins 407 can also be assembled to be freely fitted and rotated, 
then a more smooth "isokinetic inscribed meshing mechanism" can be 
realized. 
Since the input shaft 401, the output shaft 402, the centering location 
part 438 and the installing bolt holes 439 are concentrically aligned, the 
centering and fixing against the mating machine become quite easy as 
already been described. 
While the invention has been described with reference to specific 
embodiments, their descriptions are illustrative and are not to be 
constructed as limiting the scope of the invention. Various modifications 
and changes may occur to those skilled in the art without departing from 
the spirit and scope of the invention as defind by the appended claims.