Power plants – Pressure fluid source and motor – Coaxial impeller and turbine unit
Reexamination Certificate
1998-08-31
2001-04-17
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Coaxial impeller and turbine unit
C060S341000, C416S19700C, C416S228000
Reexamination Certificate
active
06216454
ABSTRACT:
This application corresponds to and claims priority under 35 U.S.C. § 119 with respect to Japanese Application No. 09(1997)-233570 filed on Aug. 29, 1997, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention generally relates to a torque converter located between an internal engine and an automatic transmission. More particularly, the present invention pertains to the construction of stator blades used in such a torque converter.
BACKGROUND OF THE INVENTION
One type of a torque converter is described in U.S. Pat. No. 4,180,978. This torque converter includes a pump impeller having a plurality of blades, a turbine runner, and a stator. The pump impeller is driven by the internal engine and is adapted to absorb torque from the engine. The turbine runner is in fluid flow relation with the pump impeller. The stator redirects fluid from the turbine runner to the pump to produce a toroidal flow path of hydraulic fluid. The blades of the pump impeller have a negative tip angle displaced in the range of 20 degrees to 30 degrees from the toroidal flow path at the fluid outlet of the pump impeller. Further, the blades of the stator have a sharp nose displaced circumferentially and angularly from the entrance flow to the stator from the turbine runner to induce turbulence in the toroidal flow path at the stator inlet at stall speeds.
In the apparatus, when the speed ratio E is small, that is to say that the turbine runner does not rotate in spite of rotating the pump impeller, the torque capacity C becomes small. The speed ratio E is the rotational speed of the turbine runner divided by the rotational speed of the pump impeller. The torque capacity C is equal to Tp/Ne
2
, where Tp equals the pump impeller torque and Ne equals the rotational number. The torque capacity C is one of the factors deciding the peak torque of the engine. Therefore, when the engine is idling, the fuel expense of the engine becomes economical.
However, in the apparatus described above, the torque capacity C is not controlled when the speed ratio is in both the middle range and the high range. Therefore, the peak torque of the engine become small such that the fuel expense is not economical.
A need thus exists for a torque converter in which during a middle and high range of operation, the torque capacity is controlled to be generally constant and less than in other known torque converters.
SUMMARY OF THE INVENTION
The present invention provides a torque converter that includes a bladed pump impeller driven by an internal engine, a bladed turbine runner in fluid flow relation with the pump impeller, and a bladed stator for redirecting fluid from the turbine runner to the pump impeller to produce a toroidal flow path of hydraulic fluid. The blades of the stator have an inlet portion facing the turbine runner and to which flows hydraulic fluid from the turbine runner, an outlet portion facing the pump impeller and discharging hydraulic fluid from the stator, a pressure surface disposed on one side of the blade between the inlet portion and the outlet portion, a suction surface disposed on another side of the blade, and a plate portion disposed near the inlet portion.
According to another aspect of the present invention, a torque converter includes a bladed pump impeller driven by an internal engine, a bladed turbine runner in fluid flow relation with the pump impeller, and a bladed stator for redirecting fluid to produce a toroidal flow path of hydraulic fluid. The blades of the stator have an inlet portion facing the turbine runner and to which flows hydraulic fluid from the turbine runner, an outlet portion facing the pump impeller and discharging hydraulic fluid from the stator, a pressure surface disposed on one side of the blade between the inlet portion and the outlet portion, and a suction surface disposed on another side of the blade. The blades of the stator are also configured to cause disorderly flow of the hydraulic fluid when the ratio of the speed of rotation of the pump impeller and the speed of rotation is less than a predetermined value reduce the torque capacity of the torque converter and produce a substantially constant torque capacity.
REFERENCES:
patent: 2961830 (1960-11-01), Dundore et al.
patent: 4180978 (1980-01-01), Maddock
patent: 4848084 (1989-07-01), Wirtz
patent: 5271716 (1993-12-01), Ejiri
patent: 6003311 (1999-12-01), Takada et al.
patent: 9-14388 (1997-01-01), None
patent: 10-252858 (1998-09-01), None
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Look Edward K.
Woo Richard
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