Metal working – Method of mechanical manufacture – Impeller making
Reexamination Certificate
1999-08-27
2001-05-29
Rosenbaum, I. Cuda (Department: 3726)
Metal working
Method of mechanical manufacture
Impeller making
C029S889200, C029S505000
Reexamination Certificate
active
06237221
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The invention relates to a method of fixing impeller blades to an impeller shell of a torque converter.
B. Description of the Related Art
A torque converter has three kinds of vane wheels, an impeller, a turbine and a stator, all arranged in an annular fluid-filled chamber defined in the torque converter. The vane wheels are adapted to transmit torque from an input rotary member to an output rotary member via working fluid in the annular fluid-filled chamber. The impeller includes an impeller shell, a large number of circumferentially spaced apart impeller blades located inside the impeller shell and an annular impeller core fixed to radially inward sides of the impeller blades.
In a conventional impeller, each impeller blade is fixed to the impeller shell in the following manner. First, the impeller shell is formed with a plurality of concavities or recesses via an embossing or deformation process. Next, the impeller blades are each formed with a plurality of projections. Next, the projections are fitted into -the concavities or recess of the impeller shell. Finally, the impeller blades are fixed to the impeller shell by brazing, or another similar welding process.
When the brazing or other similar welding process is employed for fixing the impeller blades to the impeller shell, the impeller blades and portions of the impeller shell are heated causing the impeller shell to be thermally deformed, often to a large extent.
Another method of fixing impeller blades includes forming concavities in the impeller shell, inserting tabs formed on the impeller blades into the concavities, then caulking a portion near the concavity by punching or otherwise deforming the impeller blade and/or. impeller shell. The second method is less expensive than the first method that employs brazing.
In the conventional fixing method, however, caulking, e.g., punching causes deformation in the impeller shell. This is because the outer surface of the impeller shell is entirely supported on a support base, and a portion of the support base that bears the punching load may vary each time the punching is performed. For example, if the portion bearing the load is spaced apart slightly from the portion of the impeller shell being caulked, or if the portion bearing the load is not uniformly shaped to conform to the shape of the impeller shell, the impeller shell may be deformed to a large and undesirable extent. The state or manner of deformation may also change depending on the lot of the impeller. The fixing method utilizing caulking likewise can cause large amounts of unwanted deformation in the impeller shell.
SUMMARY OF THE INVENTION
An object of the invention is to suppress deformation of an impeller shell, which occurs when impeller blades are fixed to the impeller shell.
In accordance with one aspect of the present invention, there is a method for fixing a plurality of impeller blades to an impeller shell of a torque converter, each of the impeller blades having a plurality of projections, the impeller shell having a plurality of concavities formed on an inner surface thereof for receiving the projections on the impeller blades. The method includes the steps of:
fitting -the projections of the impeller blades into the concavities in the impeller shell; and
caulking an inner surface of the impeller shell while supporting only an outer surface of the impeller shell at areas adjacent to -the concavities, thereby deforming portions of the impeller shell fixing each of the impeller blades to the impeller shell.
Preferably, in the caulking step, the deformed portions of the impeller shell are formed at a radially inward position of the impeller shell, with respect to a rotational axis of the impeller shell.
Preferably, in the caulking step, the deformed portions of the impeller shell contact and partially extend over a radially inward portion of respective impeller blades.
Preferably, in the caulking step, the deformed portions of the impeller shell partially extend over a radially inward portion of corresponding concavities formed in the impeller shell.
Preferably, the method also includes the steps of:
forming the impeller shell with three concentric rows of concavities before said fitting step;
forming each impeller blade with three projections corresponding to the three concentric rows of concavities before said fitting step; and
wherein in said caulking step, the deformed portions are located proximate only the radially innermost row of concavities of the three concentric rows of cavities, with respect to a rotational axis of the impeller shell.
Preferably, in the caulking step, the deformed portions of the impeller shell contact and partially extend over a radially inward portion of respective impeller blades.
As a result of the above aspect of the present invention, caulking of a portion of the impeller shell is performed while supporting only an outer surface of the deformed portion of the impeller shell. Therefore, deformation occurs to a lesser extent than in the prior art.
According to the above impeller blade fixing method, unwanted distortion of the impeller shell can be suppressed.
According to the above impeller blade fixing method, the deformed portion is created by deformation of the impeller shell at a location adjacent to a radially inward portion of the impeller blade, thereby forcing the projections formed on the impeller blades into firm contact with their respective concavities ensuring the rigid retention of the impeller blades in the impeller shell.
These and other objects, features, aspects and advantages of the present invention will become more fully apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings where like reference numerals denote corresponding parts throughout.
REFERENCES:
patent: 4584835 (1986-04-01), Nishi
patent: 5868025 (1999-02-01), Fukuda et al.
patent: 5946962 (1999-09-01), Fukuda et al.
Cuda Rosenbaum I.
Exedy Corporation
Shinjyu Global IP Couselors, LLP
LandOfFree
Method of fixing impeller blades of a torque converter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of fixing impeller blades of a torque converter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of fixing impeller blades of a torque converter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2459117