Internal-combustion engines – Engine speed regulator – Specific throttle valve structure
Reexamination Certificate
2002-02-04
2003-09-23
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Specific throttle valve structure
C251S309000, C251S366000
Reexamination Certificate
active
06622696
ABSTRACT:
TECHNICAL FIELD
The present invention relates to valves having rotatable valve plates for throttling the flow of gas; more particularly, to throttle valves for internal combustion engines; and most particularly, to a throttle valve having a throttle shaft of about the same diameter as the valve throat and having a valve plate integral with the shaft.
BACKGROUND OF THE INVENTION
Throttle-type valves for controlling the flow of gas are well-known. In the prior art, one type of conventional throttle valve typically comprises a body having a relatively is large-diameter first bore therethrough for passage of gas and a second relatively small-diameter bore transverse to the first bore for supporting a rotatable shaft on which is mounted a valve plate (known in the art as a “butterfly”) for controllably occluding the first bore in response to rotation of the shaft to control the flow of gas. For clarity in the following presentation, such valves are referred to as prior art butterfly valves.
Several problems exist in conventional prior art butterfly throttle valves.
First, although the air bore, or throat, of the valve body is typically cylindrical, the valve plate is not circular but preferably is slightly elliptical such that the bore is sealed with the valve plate non-orthogonal to the axis of the bore. This is intended to prevent the plate from becoming jammed, or “corked,” in the bore in the closed position. This problem can easily occur because the clearances between the valve plate and air bore in the closed position must necessarily be as small as is practically possible to minimize air leakage past the plate. Particularly in very small-displacement engines, the leakage inherent in prior art valves can be unacceptably large and irreducible without large expense in increased manufacturing control of component variability.
Second, because the valve plate is much larger in diameter than the diameter of the shaft bore, the plate cannot be formed integrally with the shaft but rather must be formed separately and mounted onto the shaft during assembly of the valve, typically by a pair of screws, after the shaft is installed into the valve body. Because of necessary tolerances in the manufacture of all components, significant and undesirable variation among valves occurs in the “ship air” volume (referring to the inherent leakage through the closed valve) of the valves as shipped from the manufacturer.
Third, the geometric relationship of the valve plate to the valve bore in a prior art butterfly valve is inherently and geometrically poor for precise flow control of gas at very low opening angles, which unfortunately is where high precision is very desirable. As the valve plate begins to rotate away from the closed position against the valve body, the entire circumference of the plate loses contact with the bore wall simultaneously, and gas flows around the entire metering perimeter of the plate; thus, the flow of gas through the valve increases from the ship air volume very rapidly with rotation of the valve plate through very small angles from closed.
U.S. Pat. No. 5,678,594 discloses a second type of prior art throttle valve which overcomes the first two of these problems but not the third. As shown presently in
FIGS. 1-3
(corresponding to the prior art
FIGS. 2
,
3
and
6
, respectively), and discussed here for clarity of presentation of the prior art, a throttle valve
10
includes a valve body
12
defining a flow path extending from a cylindrical inlet
14
to a cylindrical outlet
16
having axes
15
,
17
, respectively. The flow path is not smoothly cylindrical from inlet
14
to outlet
16
but rather is provided with transverse arcuate portions
18
(shown as “
90
” in the reference patent) purportedly to reduce the aerodynamic torque on the valve and thus reduce actuation load. Because the portions
18
lie on opposite sides of the upper and lower portions of the valve, respectively, as shown in
FIG. 3
, inlet
14
is axially offset from outlet
16
.
Valve body
12
is configured to be mounted in a duct and has two opposed
103
coaxial circular portals
20
,
22
defining a cylindrical bore
24
through valve body
12
transverse of axes
15
,
17
and forming opposed linear sealing lips
26
defining a longitudinal valve seat in body
12
.
A cylindrical “flow modulator”
28
includes a central rectangular valve plate
30
, analogous to a prior art butterfly, extending from a first edge
32
to a second edge
34
. Perpendicular to these edges, plate
30
is bounded by first and second disk flanges
36
,
38
of substantially the same outer diameter as the diameter of bore
24
and of the width between edges
32
and
34
. Flow modulator
28
also includes a small-diameter shaft portion
40
which is captured in bearings (not shown) and used for conventional rotary actuation (not shown) of the flow modulator. Edges
32
,
34
seal linearly against the valve seat defined by lips
26
over the entire length of the edges and lips when the valve is closed, unlike a prior art butterfly valve which seals radially against a cylindrical bore.
The valve disclosed in U.S. Pat. No. 5,678,594 and just described suffers from the same geometric disadvantage as the conventional butterly valves described earlier, leading to inherently imprecise flow control of gas at very low opening angles. As shown in
FIG. 3
, as the valve plate
30
begins to rotate away from the closed position, the entire lengths of edges
32
,
34
lose contact with the lips
26
simultaneously, and gas begins flowing across the entire metering length of edges
32
,
34
; thus, the flow of gas through the valve increases very rapidly with rotation of the valve plate through very small angles from closed.
Therefore, there is a strong need for an improved throttle valve wherein the flow of gas through the valve increases slowly with rotation of the valve shaft as the valve is opened.
It is a principal object of this invention to provide an improved throttle valve wherein the flow of gas through the valve increases slowly with rotation of the shaft as the valve is opened.
It is a further object of this invention to provide an improved throttle valve wherein the minimum air flow is substantially lower than that routinely achievable with prior art valves.
It is a still further object of the invention to provide an improved large-shaft throttle valve wherein the shaft is journalled in the valve body without requiring roller bearings.
It is a still further object of the invention to provide an improved throttle valve wherein the volume of idle air for each individual valve is independently adjustable after assembly such that all such valves may be adjusted to a standard ship air volume.
It is a still further object of the invention to provide an improved throttle valve requiring fewer components and therefore costing less to manufacture.
SUMMARY OF THE INVENTION
Briefly described, the present invention is directed to an improved rotary throttle valve. A valve body has a first cylindrical bore for flow of gas, such as air, therethrough between an inlet and an outlet. Orthogonal to the first cylindrical bore is a second cylindrical bore having substantially the same diameter as the first bore. A flow modulator rotatably disposed in the second bore has first and second cylindrical portions disposed respectively on opposite sides of the first bore and separated by a central plate having a width equal to the diameters of the first and second bores such that when the modulator is rotated to place the width of the plate transverse to the first bore, the edges of the plate are fully engaged with the wall of the second bore and the valve is closed. As the modulator is rotated from the closed position, the edges of the plate become progressively less engaged with the wall of the second bore, the edge of the open area following the juncture lines of the first and second bores, and the open area of the first bore increases accordingly.
Preferably, an adjustable air bleed valve is provided for calibrating a standard minimum air fl
Evans David M.
Witzel Donald G.
Argenbright Tony M.
Delphi Technologies Inc.
Griffin Patrick M.
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