Metal working – Method of mechanical manufacture – Impeller making
Reexamination Certificate
2002-07-12
2003-12-16
Vidovich, Gregory (Department: 3726)
Metal working
Method of mechanical manufacture
Impeller making
C416S180000, C029S458000
Reexamination Certificate
active
06662446
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a torque converter used for an automatic transmission mechanism of a vehicle and, more particularly, relates to components constituting an outer hull of a torque converter.
The torque converter of an automobile is equipped with a lock-up clutch which functions to improve fuel consumption of an engine while giving two operation modes, with one operation mode corresponding to a torque converter state and the other operation mode corresponding to a lock-up state. In the first operation mode (torque converter state), an output element is rotated with increasing torque by a reaction force of a stator while circulating a hydraulic oil to an impeller of the output element (generally a turbine runner) and a reaction element (generally a stator) by the rotation of an impeller of an input element (generally a pump impeller) driven by the engine. And in the second operation mode (lock-up state), the engine turns the output element by coupling the input and output element by fixing the lock-up clutch.
The Japanese Examined Patent Publication No. HEI 7-33861 of the same application discloses conventional examples of a front cover and a pump impeller, which are constructional elements of a torque converter equipped with a lock-up mechanism of the type mentioned above.
In such conventional examples, rotating power from the engine is transmitted to a flange portion, which performs an inertia function, and a starter gear is meshed with an annular ring gear. The flange and the annular ring gear are formed on an outer peripheral surface of the torque converter. The ring gear is meshed with a pinion of a starter motor at a starting time of the engine operation for transmitting the rotating force of the starter motor to a crank shaft of the engine.
FIG. 1
shows a structure of the torque converter provided with the conventional lock-up mechanism mentioned above.
With reference to
FIG. 1
, the torque converter
1
is composed of a pump impeller
3
formed by integrally coupling an impeller
2
a
to an impeller shell
2
, a turbine runner
4
and a stator
5
. The impeller shell
2
of the pump impeller
3
is integrally coupled to a front cover
6
by welding. The front cover
6
is formed on an outer peripheral surface with an annular flange portion
7
, and a drive plate
9
coupled to an engine crank shaft
8
is fastened to the flange portion
7
by a bolt. A ring gear
10
for the stator
5
is provided at an outer peripheral surface of the impeller shell
2
.
The detailed structure of the conventional torque converter will be further explained hereunder with reference to FIG.
1
.
The turbine runner
4
is mounted to a turbine hub
12
by rivets, for example, and an input shaft
13
is connected to the turbine hub
12
via a spline coupling engagement. The stator
5
is supported by a hollow fixed shaft
17
through an outer race
14
. A sprag
15
and an inner race
16
constitute a one-way clutch to be rotatable in one direction. The hollow fixed shaft
17
is fastened to a housing
19
of an oil pump
18
by bolts and is coupled to the inner race
16
via a spline engagement.
An oil pump driving shaft
20
in the shape of a sleeve is provided at a shaft core portion of the impeller shell
2
of the pump impeller
3
, and an inner rotor
21
of the oil pump
18
is coupled to the oil pump driving shaft
20
so as to be driven rotatably.
One example of such coupling structure of the inner rotor
21
to the oil pump driving shaft
20
of the impeller shell
2
is disclosed in the Japanese Utility Model Laid-open Publication No. HEI 5-34348). That is, a flat portion is formed on an outer periphery of a front (tip) end portion of the oil pump driving shaft
20
, and another flat portion is formed on an inner surface of the inner rotor
21
of the oil pump
18
, and when both flat portions are engaged, the oil pump driving shaft
20
and the inner rotor
21
of the oil pump
18
are coupled to be driven in a rotational direction.
Further, an outer periphery of a cylindrical portion of the oil pump driving shaft, at an approximately axial central portion of the oil pump, is rotatably supported by an inner peripheral surface of a bush
22
fixed to the housing
19
of the oil pump
18
so as to bear the driving load of the oil pump
18
at this portion. Accordingly, a driving load in proportion to a discharge pressure (line pressure) of the oil pump
18
is applied to the flat portion of the oil pump driving shaft
20
and the portion thereof supported by the bush
22
.
Stator collars
23
a
and
23
b
are mounted on both sides of the sprag
15
of the one-way clutch, and thrust bearings
24
a
and
24
b
are interposed between a pilot boss portion
32
, as described hereinafter, and the turbine hub
12
and between the stator collar
23
b
and the oil pump driving shaft
20
, respectively.
The pump impeller
3
driven by the rotation of the crank shaft
8
of the engine acts to circulate the hydraulic oil filling a torque converter chamber
25
. The hydraulic oil circulates in passages of the respective impellers of the pump impeller
3
, the turbine runner
4
and the stator
5
, whereby the turbine runner
4
is rotated while increasing the torque by the reaction force due to the operation of the stator
5
, and the rotating force is transmitted to the input shaft
13
through the turbine hub
12
and then to an automatic transmission mechanism or non-stage transmission mechanism, not shown.
A lock-up clutch hub
27
of a lock-up clutch
26
is fastened to the turbine hub
12
by rivets, and the lock-up clutch hub
27
is provided with a torsional damper
28
for damping a shock at a time of clutch engagement and for absorbing vibrations or noises of the driving system.
The lock-up clutch
26
is provided with a lock-up piston
29
at a portion between the lock-up clutch hub
27
and the front cover
6
. And the lock-up piston
29
is fitted to the turbine hub
12
in a fashion that the inner peripheral portion of the lock-up piston
29
is slidable in an axial direction of the turbine hub
12
in a liquid tight manner with respect to the outer peripheral portion of the turbine hub
12
. The inside inner peripheral portion of the torsional damper
28
is spline-engaged with the outer peripheral portion of the lock-up clutch hub
27
. Further, the lock-up piston
29
is provided with a lock-up facing
30
on a side surface portion on the side of the front cover
6
.
A front hydraulic chamber
31
is defined between the lock-up piston
29
and the front cover
6
. The engine crank shaft
8
is formed with a center hole into which a pilot boss portion
32
protruding from the front cover
6
is fitted so as to achieve a rotational axis alignment of the torque converter
1
. The front hydraulic chamber
31
is communicated with an oil passage
33
formed within the input shaft
13
and is then communicated with a control valve of a hydraulic controller of the automatic transmission mechanism or non-stage transmission mechanism, not shown.
The torque converter
1
has an oil passage between the hollow fixed shaft
17
and the oil pump driving shaft
20
. The passage is communicated with a groove formed on the side surface of the thrust bearing
24
b
disposed between the stator collar
23
b
and the oil pump driving shaft
20
. This passage is then communicated with the hydraulic controller.
At the lock-up time, a hydraulic pressure is applied to the turbine-side side surface of the lock-up piston
29
from the inside of the torque converter
1
through the oil passage between the stator collar
23
b
and the oil pump driving shaft
20
, and at the same time, the pressurized oil in the front hydraulic chamber
31
is drained to thereto cause a pressure difference between the front and rear portions of the lock-up piston
29
(so as to make the hydraulic pressure in the front hydraulic chamber
31
smaller than that in the torque converter). Thus, the lock-up piston
29
is pushed to the front cover
6
, and via the lock-up facing
30
th
Kobayashi Toshio
Yamanaka Shigeaki
Jimenerz Marc
Kubota Iron Works Co., Ltd.
Vidovich Gregory
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