ВУЗ:
Составители:
Рубрика:
75
e
t
= Overall efficiency of planetary
gear train
F = Tangential force acting at the
pitch circle of the driving
gear, lb
L = Tooth mesh power loss in a
planetary
gear pair, ft-lb per sec
L
t
= Total tooth mesh power loss
in a planetary gear train, ft-lb
per
sec
l = Tooth mesh loss in a
conventional gear pair, ft-lb per
sec
l
t
= Total tooth mesh loss in a
conventional gear train, ft-lb per
sec
m = Speed ratio of gear
pair
train
P
i
, P
o
= Input and output power,
respectively, ft-lb per
sec
R = Planetary velocity
ratio defined by
Equation 6
v = Pitch-line velocity of gear pair, fps
v
e
= Velocity of engagement of a gear
pair, fps
∆ = Ratio of tooth mesh loss to input
power in a gear pair
η = Efficiency
of conventional gear
pair
η
t
= Overall efficiency of conventional
train
ω = Angular velocity, radian·per sec
Basic Considerations
: Certain general concepts of gear
performance will be useful in analysis of planetary gear systems and
perhaps should be reviewed.
The tooth mesh loss in a pair of gears with fixed centers is
i
PFvl
∆
=
∆
=
(1)
where symbols are defined in Nomenclature. The efficiency of a drive
system consisting of one such pair of gears is
∆−=
−
==η=η 1
0
i
i
i
t
P
lP
P
P
. (2)
For a train with more than one pair of gears,
(
)
(
)
2221
11
∆
−
∆
−
=
η
η=η K
t
, (3)
where subscripts 1 and 2 identify individual meshing pairs in the train.
If ∆
1
=∆
2
…=∆
n
=∆, then
(
)
n
n
t
η=∆−=η 1 (4)
Principal contributing sources of power losses in gear trains are as
follows:
1. Sliding friction between meshing tooth surfaces.
2. Oil churning.
3. Friction in shaft support bearings.
Tooth mesh loss, as the first type will be called here, depends upon
the geometry of tooth profiles and upon a "mean coefficient of friction"
Страницы
- « первая
- ‹ предыдущая
- …
- 73
- 74
- 75
- 76
- 77
- …
- следующая ›
- последняя »
