Torque converter

Details Torque converter Torque converter

2000-11-03

2002-12-03

Look, Edward K. (Department: 3745)

Power plants

Pressure fluid source and motor

Coaxial impeller and turbine unit

C060S367000

Reexamination Certificate

active

06487855

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in a torque converter, comprising a pump impeller connected to a driving shaft, a turbine impeller connected to a turbine shaft, a stator impeller disposed between the pump impeller and the turbine impeller, and a free wheel which is interposed between the stator impeller and a stationary structure and operable to lock the stator impeller in order to allow the stator impeller to bear a reaction force generated with the amplification of torque between the pump and turbine impellers.
2. Description of the Related Art
In such a conventional torque converter, a cylindrical stationary shaft is disposed on an outer periphery of a turbine shaft and surrounded by a boss of a stator impeller, and a free wheel is interposed between the stationary shaft and the boss of the stator impeller, as disclosed in Japanese Patent Publication No.7-33861, for example.
In the torque converter including the free wheel interposed between the boss of the stator impeller and the cylindrical stationary shaft surrounded by the boss, the following problem is encountered: the size of the diameter of the stator impeller and thus, the diameter of the entire torque converter, is necessarily increased due to the concentric disposition of the stator impeller and the free wheel.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a torque converter of the above-described type, wherein a reduction of the diameter of the entire torque converter can be achieved, despite of the presence of the free wheel.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a torque converter comprising a pump impeller connected to a driving shaft, a turbine impeller connected to a turbine shaft, a stator impeller disposed between the pump impeller and the turbine impeller, and a free wheel which is interposed between the stator impeller and a stationary structure and operable to lock the stator impeller in order to allow the stator impeller to bear a reaction force generated with the amplification of torque between the pump and turbine impellers, wherein the stator shaft connected to the stator impeller is disposed with a tip end thereof being passed through the turbine shaft to protrude outside the turbine shaft, the tip end of the stator shaft being connected to the stationary structure through the free wheel.
The stationary structure and the driving shaft correspond to a crankcase
1
and a crankshaft
2
in each of embodiments of the present invention, respectively, which will be described hereinafter.
With the first feature, the tip end of the stator shaft passed through the turbine shaft to protrude outside of the turbine shaft is connected to the stationary structure. Therefore, the stator shaft may be merely connected to the stator impeller and hence, it is possible to reduce the diameter of the stator impeller and thus, the diameter of the entire torque converter, irrespective of the presence of the free wheel. Moreover, in a coupled state in which the stator impeller is rotated along with the pump impeller and the turbine impeller, the stator shaft connected to the stator impeller is rotated at substantially the same speed as the driving shaft and the turbine shaft. Therefore, a difference in relative rotational speeds between adjacent ones of the driving shaft, the turbine shaft and the stator shaft is extremely small and hence, the load of each of bearings for these shafts is alleviated, whereby an enhancement in durability thereof can also be provided.
According to a second aspect and feature of the present invention, in addition to the first feature, the turbine impeller is disposed at a location displaced from the pump impeller toward a case carrying the driving shaft; the turbine shaft protruding toward the case is secured to the turbine impeller; the free wheel is interposed between the tip end of the stator shaft passed through the turbine shaft and the case; and the turbine shaft is provided with a driving gear of a primary reducing device, which connects the turbine shaft and an input shaft of a transmission to each other between the turbine impeller and the free wheel.
With the second feature, the driving gear of the primary reducing device can be disposed as close to the case as possible, while avoiding an interference with the free wheel. Therefore, during operation of the primary reducing device, it is possible to suppress a bending moment exerted to the driving shaft by the driving gear to a small level to enhance the durability of the driving shaft.
According to a third aspect and feature of the present invention, in addition to the first or second feature, the stator shaft is relatively rotatably carried on the driving shaft, and the free wheel comprises an outer race formed at the tip end of the stator shaft, an inner race relatively rotatably carried on the driving shaft and non-rotatably connected to the case, and a sprag interposed between both of the races.
With the third feature, both of the outer race and the inner race are carried on the driving shaft. Therefore, a high accuracy of concentricity can be provided to the outer and inner races, whereby the operation of the free wheel can always be stabilized.
According to a fourth aspect and feature of the present invention, in addition to the first feature, the pump impeller has a boss carried on the driving shaft with a first bearing interposed therebetween; the stator shaft leading to a boss of the stator impeller is disposed concentrically around an outer periphery of the driving shaft; the turbine impeller has a boss carried on the stator shaft with a second bearing interposed therebetween, and an operating oil is supplied into an oil chamber defined between the pump impeller and the turbine impeller through between the first and second bearings; and the first and second bearings are provided with bi-directional seal means for inhibiting the passing of a fluid such as air from any of the inside and outside of the bearings.
With the fourth feature, the bi-directional seal means inhibits the passing of fluid such as air to each of the bearings from any of the inside and outside of each bearing. Therefore, when the hydraulic pressure supplied to the torque converter is low, it is possible to inhibit the outside air from entering the inside of the torque converter through the first and second bearings, despite the acceleration of the rotation of the pump impeller, thereby preventing a reduction in transmitting efficiency due to the incorporation of the air into the operating oil. When the hydraulic pressure supplied to the torque converter is raised, such hydraulic pressure can be inhibited from leaking to the outside through the first and second bearings, thereby maintaining the internal hydraulic pressure in the torque converter at a high level to enhance the transmitting efficiency. Thus, it is possible to ensure a high transmitting efficiency, irrespective of the level of the hydraulic pressure supplied.
According to a fifth aspect and feature of the present invention, in addition to the first feature, the pump impeller and the turbine impeller have core rings relatively rotatably lapped on a core ring of the stator impeller, and a lap gap g between adjacent ones of the core rings and an inner circumferential radius R of the core ring of the stator impeller are set to have a relation of g/R≦1.0%.
With the fifth feature, when the oil within the torque converter is passed from the turbine impeller through the stator impeller toward the pump impeller during the amplification of torque, a relatively large difference in pressure is generated between an inlet and an outlet of the stator impeller. However, the lap gap between adjacent ones of the core rings exhibits a large throttling resistance under the establishment of g/R≦1.0% and hence, it is possible to effectively inhibit the flowing-out of the oil from the turbine impeller into an in-core oil

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