Fluid handling – Processes – Cleaning – repairing – or assembling
Reexamination Certificate
1999-08-06
2001-07-24
Shaver, Kevin (Department: 3754)
Fluid handling
Processes
Cleaning, repairing, or assembling
C251S263000, C251S308000, C251S294000, C251S313000, C251S337000
Reexamination Certificate
active
06263898
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to combustion air induction systems for internal combustion engines of vehicles. More particularly, it relates to throttle valves for such air induction systems and methods for assembling them.
BACKGROUND OF THE INVENTION
Internal combustion engines are often provided with a throttle valve within their combustion air induction systems to control combustion airflow rate. The throttle valve is typically in the form of a butterfly valve, having a disk secured to a throttle shaft which is journaled to the generally cylindrical internal wall surface of a throat of a throttle body. The diameter of the disk is only slightly smaller than is the inside diameter of the throat, whereby the throttle plate may block all but a small portion of the air from passing through the throat in an idle condition. Typically, a return spring is used to bias the throttle shaft and butterfly closed with respect to the throat, shutting off almost all the airflow through the throttle valve.
The return springs of such throttle valves are assembled such that they provide a predetermined preload to the throttle shafts. This preload is carefully selected to provide a sufficient force to close the throttle valve when the throttle valve actuating device is released, yet not to provide a force that substantially resists the throttle valve actuating device. Such devices typically include mechanical links, cables or motors attached to an arm extending from the throttle shaft.
Traditional return springs are difficult to assemble quickly and accurately. They are most commonly coil springs that are coiled loosely about the throttle shaft to permit them to be readily tightened or loosened as the throttle shaft is rotated and the valve is opened and closed, respectively. When a throttle valve is assembled, the return spring must first be placed about the throttle shaft. Once it is in position the throttle shaft is then inserted into the throttle body. During this process the free ends of the spring must be twisted about the shaft to apply the proper preload to the spring. While the ends of the spring are being held with the appropriate amount of preload, one end must be transferred to the throttle body and the other end must be transferred to the throttle shaft. In this manner, the preload applied to the spring is transmitted to the throttle body and the throttle shaft. By transferring the ends of the spring to the throttle shaft and throttle body, the preload functions to hold the throttle shaft closed with respect to the throttle body. If a free end of the spring is released prematurely, the spring can rapidly and partially uncoil, causing the preload to be dissipated. This typically requires that the shaft be withdrawn from the throttle body, the spring recoiled, and the shaft reinserted in the throttle body.
What is needed, therefore, is a more efficient method for assembling a throttle valve and an improved throttle valve construction that will permit the throttle valve to be assembled more rapidly and conveniently while reducing the risk that the spring will uncoil.
SUMMARY OF THE PRESENT INVENTION
In accordance with a first embodiment of the invention, a throttle shaft assembly is provided for insertion into a throttle body to form a throttle valve including a swaddle shaft having a cam portion coupled to a shaft portion wherein the shaft portion is configured to be inserted into a throttle body, a throttle return spring coiled about the throttle shaft and having first and second ends. The first end engaged to the cam portion of the throttle shaft and the second end configured to engage a spring support on a throttle body, and a throttle spring cover substantially surrounding the throttle return spring and slideably mounted on the throttle shaft. The spring may be a cylindrically coiled spring with a first end extending through an aperture in the cover. The throttle spring cover may have a plurality of radially inwardly extending cover supports and the throttle shaft may have a circular groove where the fingers are adapted to slideably engage the circular groove. The cam portion of the throttle shaft assembly may include a spring support configured to engage the second end of the spring. The cam may be configured to restrain both the first and second ends of the spring whereby the spring is maintained in a preloaded condition. The cam and spring may also be configured to release the second end of the spring onto a spring support on the throttle body.
In accordance with the second embodiment of the invention a method of installing a throttle shaft assembly including a throttle shaft with cam portion, a throttle return spring configured to be coiled about the throttle shaft and a cover substantially surrounding the coil spring and coupled to the throttle shaft is provided including the steps of inserting the throttle return spring into the cover, inserting the throttle shaft through an aperture in the cover, and sliding the spring and cover down the throttle shaft. This method may include the step of inserting a free end of the spring through an aperture in the cover. It may also include the step of engaging the first end of the spring with the cam portion. The method may include the step of engaging the first end of the spring with the cam to restrain its free circumferential rotation about the throttle shaft in a first direction, preloading the spring by coiling the spring tighter, and engaging a second end of the preloaded spring with the cam portion to restrain its free circumferential rotation about the throttle shaft in a second direction opposite the first direction. The method may also include inserting the throttle shaft into a throttle body and transferring a preload of the preloaded spring from the throttle shaft to the throttle body. The step of transferring the preload may include the steps of releasing the second end of the spring from the cam to permit it to rotate in the second direction, rotating the spring to permit a partial release of the preload, and engaging the second end of the spring with a throttle body to limit further rotation in the second direction and further release of preload.
REFERENCES:
patent: 4285499 (1981-08-01), Zukausky
patent: 4625943 (1986-12-01), Groger
patent: 4840349 (1989-06-01), Peter et al.
patent: 4867415 (1989-09-01), Andrea
patent: 4880207 (1989-11-01), Matsumoto et al.
patent: 5168852 (1992-12-01), Moriguchi et al.
patent: 5263449 (1993-11-01), Swartzendruber
patent: 5509396 (1996-04-01), Tamaki
patent: 5522361 (1996-06-01), Pickman et al.
patent: 5666988 (1997-09-01), Becker
patent: 5685521 (1997-11-01), Yoshida et al.
patent: 5762044 (1998-06-01), Hollister et al.
patent: 5878715 (1999-03-01), Hernandez et al.
patent: 5996551 (1999-12-01), Schroder
Daly Paul D.
Di Ponio Rosario
Vanderveen James
Bastianelli John
Shaver Kevin
Siemens Canada Limited
LandOfFree
Throttle shaft with return spring and spring cover and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Throttle shaft with return spring and spring cover and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Throttle shaft with return spring and spring cover and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2492587