Valves and valve actuation – Rotary valves – Butterfly
Reexamination Certificate
2000-09-05
2002-04-09
Kaufman, Joseph A. (Department: 3754)
Valves and valve actuation
Rotary valves
Butterfly
C251S123000, C251S275000
Reexamination Certificate
active
06367772
ABSTRACT:
TECHNICAL FIELD
The present invention relates to carburetors and throttle bodies as used in internal combustion engines. More particularly, the present invention relates to throttle bodies that are adapted to pass air to a manifold associated with the engine. Additionally, the present invention relates to modifications of the air passageways found in the throttle body so as to obtain greater volumetric efficiency at low r.p.m.'s, for the engine, compared to current standard designs.
BACKGROUND ART
Conventional throttle bodies are mounted within the air intake stream of an internal combustion engine. Typically, a butterfly valve is employed to control the amount of air flow through the throttle body and consequently, the entire r.p.m. speed. The butterfly valve is mounted on a throttle shaft, which is, in turn, coupled to the vehicle accelerator pedal and possibly other actuating mechanisms.
Present internal combustion engines that utilize liquid fuel will typically utilize a throttle mechanism which is formed of an external block containing one or more cylindrical passageways.
These passageways are subjected to a constrictive flow by a thin cylindrical solid disk contained within the cylindrical passageway. The disk is on a centrally located axle located at the mid-point of and center-line transverse to the passageway. The rotation of the axle/disk assemblage causes the passageways to be variably closed or opened in unison. Under normal operating conditions, aspirated air is allowed to flow through these passageways and introduced into the cylinders of the engine. The flow of aspirated air can be controlled by the rotation of the disk contained within the passageway. The amount of this aspirated air, relative to the subsequent injection of liquid fuel, determines what is normally termed volumetric efficiency. This capacity to fill a cylinder or cylinders, to the greatest amount possible with the optimum fuel/air mixture, determines the force engendered on the piston or pistons upon ignition of this mixture. Typically, at slow speeds or low r.p.m.'s, the volumetric efficiency of an engine is lower than that achieved at higher speeds. This occurs principally because of the high constriction of air flow due to the position of the disk in the air flow passageway of the throttle body mechanism. The rotation and position of the disk does not result in a linear increase in the area exposed to air flow. For example, ten degrees of rotation of the disk does not result in double the air flow as a rotation of only five degrees. When the disks are fully closed in the throttle body, it is considered to be in an “idle” position with aspirated air flow at a bare minimum. At opening, in present throttle bodies, the amount of aspirated air is very slowly increased. As opening continues, the amount of aspirated air is dramatically increased and, as a result, volumetric efficiency increases.
FIG. 1
illustrates a conventional throttle body
10
as used on an internal combustion engine. The throttle body assembly
10
includes a throttle body housing
12
which assembles into an air intake system for an internal combustion engine, not shown. The throttle body housing
12
includes air flow bores
14
and
16
through which intake air is directed during operation of the internal combustion engine. The output of the throttle body assembly
10
will direct air to the manifold of the internal combustion engine. From the manifold, air can be directed into the engine cylinders for mixture with the fuel.
In
FIG. 2
, it can be seen that the air flow bores
14
and
16
are closed by the use of disks
18
and
20
, respectively. Disks
18
and
20
are affixed centrally to an axle
22
extending transversely across the longitudinal axis of the air flow bores
14
and
16
. The rotation of the axle
22
will cause a corresponding rotation of each of the disks
18
and
20
so as to allow air flow through the bores
14
and
16
, respectively.
In
FIG. 3
, there is shown a cross-sectional view of the air flow bore
14
. It can be seen that the disk
18
is shown in a first position in which the outer periphery of the disk
18
rests against a seat
24
formed on the interior wall
26
of the throttle body
12
. When the disk
18
has its periphery against the seat
24
, the air flow bore
14
is closed so as to prevent air from passing therethrough. When the accelerator of the vehicle is pressed downwardly, the disk
18
will pivot about axle
22
so as to allow air flow to pass in the area beyond the periphery
28
of disk
18
and the wall
26
of the throttle body
12
. The amount of rotation of the disk
18
will determine the amount of air that is possible to flow in the spaces between the periphery
28
of the disk
18
and the wall
26
of the throttle body
12
.
In
FIG. 3
, it can be seen that the air flow bore
14
has a first section
30
and a second section
32
arranged on opposite sides of the disk
18
. The wall
26
in section
30
is of substantially straight and even diameter extending to the seat
24
. Similarly, the wall
34
in the second section
32
is substantially straight and uniform and extends from the seat
24
.
In normal use, a volumetrically inefficient amount of air will flow past the disk when the disk
18
is rotated only with small angular deflection. As such, the engine will receive a volumetrically inefficient amount of air. Ultimately, when the disk
18
has rotated fully, the engine will run at an optimum volumetric efficiency at a predetermined operational speed.
Several problems have been associated with attempts to increase the diameter of the air flow bore
14
in the second section
32
. Initially, the restrictions caused by the casting of the throttle body
12
will prevent any undue expansion of such air passageway. The relatively small diameter of the air flow bore
14
serves to create better transitions for the power train of the vehicle. Additionally, an increase in the diameter of the bore associated with the air flow passage is believed to create non-laminar flow and thus create an inefficiency in the delivery of air to the manifold.
In the past, various patents have issued relating to the delivery of air to the cylinders of a vehicle. In particular, U.S. Pat. No. 3,721,431, issued on Mar. 20, 1973 to P. Landrum, describes a fuel preparation system for a carburetor which utilizes an air supply conduit of predetermined dimensions communicating with each idle port of the carburetor with means for heating air passing through a conduit at predetermined temperature. Lateral openings in air supply conduits adjacent to the idle port receive fuel from the fuel supply passageway to supply heated mixture of fuel and air to the idle port.
U.S. Pat. No. 4,078,025, issued on Mar. 7, 1978 to T. Kato teaches a carburetor having an air port provided adjacent a slow port so as to supply air from the air port when fuel is supplied from the slow port in a slow speed operation of the engine. The air port is biased with respect to the slow port so that the supply of air from the air port is more rapidly reduced than the supply of fuel from the slow port in the transition region from a slow speed operation to the normal operating condition. This will compensate for a delay in the fuel supply from a main nozzle in the transition region.
U.S. Pat. No. 4,305,892, issued on Dec. 15, 1981 to I. H. Hallberg, describes a carburetor in which fuel is supplied to a pair of tubular members. These tubular members may be of equal or different diameters and are disposed across a housing opening through which air flows. The velocity of such air is controlled by a throttle valve or by a damper means. Each tubular member is constructed with a generally upwardly directed slot or fuel gap such that the air strips fuel therefrom. The throttle valve or damper may be of the iris type or of a type having a pair of vanes pivoted outwardly of the center thereof so as to initially open at the center thereof. At small throttle openings, air flowing to the engine is concentrated over the fuel
Bonderer D. Austin
Harrison & Egbert
Kaufman Joseph A.
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