Fluid reaction surfaces (i.e. – impellers) – Specific drive or transmission means – Hand mixers
Reexamination Certificate
1998-08-12
2002-04-02
Ryznic, John E. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific drive or transmission means
Hand mixers
C074S410000
Reexamination Certificate
active
06364611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a helicopter power transmitting apparatus for transmitting torque generated by a helicopter engine to a main rotor, etc., and more specifically to a power transmitting apparatus for transmitting engine rotational torque to the main rotor through a single input gear shaft in mesh with a plurality of gear trains uniformly, where the torque is equally transmitted to each gear trains, in order to reduce the weight and size of the apparatus.
2. Description of the Prior Art
The helicopter power transmitting apparatus is an apparatus for transmitting a rotational torque generated by a helicopter engine to a main rotor, a tail rotor, an electric dynamo, a hydraulic pump, etc., whose arrangement on a helicopter is shown in FIG.
7
. In
FIG. 7
, an output shaft
41
of an engine
40
is linked with a power transmitting apparatus
42
, and a drive shaft
43
extending from the power transmitting apparatus
42
drives a main rotor
44
. In addition, a tail rotor drive shaft
45
extends from the power transmitting apparatus
42
to drive a tail rotor
46
.
In the helicopter power transmitting apparatus of the above-mentioned prior art, since both light-weight and small-size characteristics are severely required, it is effective to adopt such a construction that double gear trains are provided for a single input shaft linked with an engine output shaft so that the engine rotational torque can be transmitted to a large-diameter gear for driving the main rotor through a pair of gear trains, as disclosed by a document “A 2400 Kw Light Weight Helicopter Transmission with Split-Torque Gear Trains”: ASME 84-DET-91. In this prior art, the helicopter power transmitting apparatus is such that the rotational torque applied to a single input shaft is transmitted to a large-diameter main rotor driving gear through the pair of the gear trains, since there inevitably exist some manufacturing tolerance, shaft deformation, etc., it has been difficult to uniformly transmit the rotational torque to the main rotor through the pair of the gear trains as expected.
With respect to this apparatus, a related art already filed in Japan by the same Applicant as Japanese Patent Application No. 6-80475 will be first explained with reference to
FIG. 8
, in which the helicopter power transmitting apparatus is provided with the pair of the gear trains for automatically distributing the rotational engine torque uniformly.
As shown in
FIG. 8
, in this helicopter power transmitting apparatus
51
, a largediameter gear
53
is directly linked with a main rotor drive shaft
52
. This largediameter gear
53
is in mesh with a pair of first and second small-diameter gears
54
a
and
54
b
having the same diameter and the same number of teeth and arranged at a predetermined angular interval.
A first largediameter helical gear
56
a
is linked with the upper side of a first shaft
55
a
of the first small-diameter gear
54
a
. Further, a second largediameter helical gear
56
b
is fixed to the lower side of a second shaft
55
b
of the second smalldiameter gear
54
b
. The first largediameter helical gear
56
a
and the second largediameter helical gear
56
b
are the same diameter and the number of teeth, but opposite to each other in the inclination direction of the helical gear, so that the thrust directions generated by the two largediameter helical gears
56
a
and
56
b
are determined opposite to each other.
An input shaft
57
is arranged between the two first and second shafts
55
a
and
55
b
roughly in parallel to the two shafts
55
a
and
55
b
. Further, an outer cylinder
58
is arranged so as to be axially and slidably fitted to the outer side of the input shaft
57
. Further, a first smalldiameter helical gear
59
in mesh with the first largediameter helical gear
56
a
and a second small-diameter helical gear
59
′ in mesh with the second largediameter helical gear
56
b
are arranged on the upper and lower ends of the outer cylinder
58
, respectively.
The first smalldiameter helical gear
59
and the second smalldiameter helical gear
59
′ are the same in diameter and the number of teeth, but opposite to each other in the inclination direction of the helical gear, so that the thrust directions generated by the two smalldiameter helical gears
59
and
59
′ are determined opposite to each other.
Further, on the lower end of the input shaft
57
, two bevel gears
60
and
61
are arranged to transmit the rotational torque generated by the engine to the power transmitting apparatus
51
. In addition, a gear
62
is in mesh with the largediameter gear
53
, to drive a tail rotor drive shaft
65
through two bevel gears
63
and
64
.
In the above-mentioned conventional helicopter power transmitting apparatus
51
, the rotational torque applied to the input shaft
57
is transmitted to the largediameter gear
53
via two transmission routes. That is, the first transmission route is to transmit the rotational torque of the input shaft
57
to the largediameter gear
53
by way of the outer cylinder
58
, the first smalldiameter helical gear
59
, the first largediameter helical gear
56
a
, and the first small-diameter gear
54
a
. Further, the second transmission route is to transmit the rotational torque of the input shaft
57
to the largediameter gear
53
by way of the outer cylinder
58
, the second smalldiameter helical gear
59
′, the second largediameter helical gear
56
b
, and the second smalldiameter gear
54
b
. Therefore, the outer cylinder
58
is so constructed as to be slidable according to a difference between two thrust forces of mutually opposite directions generated by the first and second smalldiameter helical gears
59
and
59
′, respectively. Here, since the phase difference between the first and second smalldiameter helical gears
59
and
59
′ can be eliminated by the vertical slidable motion of the outer cylinder
58
, it is possible to transmit the rotational torque uniformly through the two transmission routes.
In the above-mentioned helicopter power transmitting apparatus, however, as far as the rotational torque to be transmitted is small, since the outer cylinder can be well slid up and down, the rotational torque can be distributed uniformly. However, once the rotational torque exceeds a predetermined value, since a frictional force between the outer cylinder
58
and the input shaft
57
increases, the outer cylinder
58
cannot slide. Therefore, when the load of the helicopter is large, there exists a problem in that the rotational torques transmitted from the first and second smalldiameter gears
54
a
and
54
b
to the largediameter gear
53
, respectively are not well balanced.
To overcome the above-mentioned problem, although the non-slidable condition due to increased friction of the outer cylinder may be somewhat improved by using a ball-splined joint structure such that balls intervene between the input shaft and the outer cylinder, there arises another problem in that the apparatus is rather complicated and thereby becomes costly.
Therefore, the object of the present invention is to provide the helicopter power transmitting apparatus which can transmit the engine input to the main rotor, etc. through the pair of the gear trains securely and smoothly, in spite of a simple construction.
SUMMARY OF THE INVENTION
With these problems in mind, therefore, it is the object of the present invention to provide a helicopter power transmitting apparatus of a simple construction, which can securely and uniformly transmit an engine output power to a main rotor, etc. through a pair of gear trains.
To achieve the above-mentioned object, the first aspect of the present invention provides a helicopter power transmitting apparatus including: a largediameter gear (
3
) linked with a main rotor driving shaft (
2
); first and second smalldiameter gears (
4
a
,
4
b
) both having the same diameter and the same number of teeth and arranged at a predetermined angular in
Matsuda Hidemi
Yamamoto Hideteru
Fuji Jukogyo Kabushiki Kaisha
Ryznic John E.
Smith , Gambrell & Russell, LLP
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