ВУЗ:
Составители:
Рубрика:
83
input shafts D, and D', is also positive. Thus, the product of torque and
angular velocity for gear C' will also be positive, making this gear the
driver in the train with the stopped planet cage.
Planetary velocity ratio, output power, tooth mesh loss and
efficiency for this train can be determined from Equations 11 to 15.
There is a difference, however, in the value of R. In this train, R is
always smaller than 0.5. Therefore, the efficiency of this train is
considerably higher than that of a conventional train with comparable
gear arrangement. Here again, however, the speed ratios possible with
trains of this type are relatively small.
Other combinations of fixed, input and output members are also
possible with the basic system shown in Fig. 2a. Each arrangement will
constitute a different mechanism having different speed ratio and
efficiency. These efficiencies may be easily determined by the foregoing
method.
4. Compound Systems
The speed ratio of a planetary train can be increased by using the
so-called compound arrangement shown schematically in Fig. 6. In this
train, sun gear A is connected to input shaft D. Output shaft C is
connected to planet cage G which carries planet gears B and J. Planet
gear J engages the fixed ring or internal gear, C. Speed ratio of this train
is
JA
BC
H
D
p
dd
dd
m +=
ω
ω
= 1 (18)
This expression shows that the speed ratio which can be obtained
through this train is approximately of the same magnitude as can be
obtained by means of a conventional gear train having two pairs of gears.
Fig. 5—Simple planetary gear train in
which the sun gear is the fixed member.
The train is a modification of the
arrangement shown in Fig. 3a
Sun gear, A
(fixed)
Planet gear, B
Ring gear, C
Input shaft, D
Output
shaft, H
Planet
ca
g
e, G
Output
shaft, H
Ring gear, C
(fixed)
Sun gear, A
Planet cage, G
Planet gear, B
Planet gear, J
Input shaft, D
Fig. 6—Compound planetary gear train
for large speed ratios
Страницы
- « первая
- ‹ предыдущая
- …
- 81
- 82
- 83
- 84
- 85
- …
- следующая ›
- последняя »
