Waste gate control for supercharged engines

A waste gate for an internal combustion engine having an exhaust gas driven supercharger supplying air under pressure to the engine intake manifold which is sensitive to the intake manifold pressure and reduces the quantity of air supplied to the intake manifold by the supercharger when the pressure in the intake manifold attains a predetermined value for efficient use of fuel supplied to the engine and increasing its power output.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to internal combustion engines equipped with 
a supercharger for supplying air under pressure to the intake manifold and 
more particularly to a waste gate communicating with the engine exhaust 
gases and responsive to intake manifold pressure for preventing excess 
intake manifold pressure above a desired maximum. 
In a supercharged gasolene engine, such as used on automobiles and 
motorcycles, the supercharger will usually include a compressor impeller 
on one end of a shaft with a radial inward flow turbine wheel at the other 
end. Air fuel mixture enters the compressor and is compressed and passed 
to the engine intake manifold and then to the combustion chambers. When 
the exhaust gases leave the combustion chambers and flow through the 
exhaust manifold and exhaust pipe they are increased to a considerably 
higher volume and temperature and rotate the turbine wheel for operating 
the compressor. The greater volume of gas passing through the turbine 
wheel than through the compressor results in useful work obtained from the 
system and the air fuel mixture being passed into the cylinders at a 
pressure higher than atmospheric. Thus, more pounds of air can be 
delivered to the engine as compared to one which is naturally aspirated 
resulting in greater efficiency of fuel burned and greater power obtained 
from the engine. However, at higher engine speeds a supercharger will 
supply excessive higher temperature air fuel mixture to the intake 
manifold resulting in higher exhaust back pressure which reduces fuel 
economy without increasing engine power output. 
This invention prevents the intake manifold pressure exceeding a 
predetermined value by venting excess exhaust gas back pressure, above a 
desired maximum, upstream with respect to the supercharger. 
2. Description of the Prior Art 
Prior patents, such as U.S. Pat. Nos. 3,035,408 and 3,365,878, generally 
disclose waste gate controls which feature a perforated diaphragm 
connected with and opening and closing a valve to release or contain 
exhaust gas pressure driving a supercharger. 
The principal disadvantage of this type waste gate control is the 
perforated diaphragm which has a relatively short life when compared with 
an imperforate diaphragm and further the control apparatus is bulky and 
for this reason is objectionable when attached to a relatively small 
engine, such as a motorcycle. 
This invention provides a waste gate which features an imperforate 
diaphragm arranged in a plane parallel with the stem of the valve 
controlling exhaust gas pressure and has an overall low profile and when 
attached to a small engine, such as a motorcycle, does not materially 
increase the overall dimensions thereof. 
SUMMARY OF THE INVENTION 
A valve housing is provided with an inlet port communicating with an 
exhaust port with the inlet port being adapted to be connected with an 
internal combustion engine exhaust pipe. The inlet port is opened and 
closed by a valve having a stem slidable in the housing and normally 
spring urged to a valve closed position. A pressure sensitive chamber, 
formed in the housing, is normally exhausted by an imperforate diaphragm 
normally urged toward a pressure chamber exhausted position by a bell 
crank pivotally connected with the housing and biased toward the diaphragm 
by the valve closing spring. The pressure chamber is connected by tubing 
with the engine intake manifold for biasing the diaphragm outwardly of the 
pressure sensitive chamber and opening the inlet port closing valve 
against its spring pressure when the engine intake manifold pressure 
attains a predetermined limit. 
The principal objects of this invention are to provide a waste gate, for a 
motorcycle, or the like, having a side mounted diaphragm describing a 
minimum silhouette area with a diaphragm operated lever opening a waste 
gate gas exhaust valve, normally seated on a floating valve seat, against 
valve spring pressure in response to the diaphragm being pushed in one 
direction by intake manifold pressure which by the lever generates a 
pushing action on the valve and in which at least a portion of the valve 
stem and spring is exposed to ambient air streams for cooling.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Like characters of reference designate like parts in those figures of the 
drawings in which they occur. 
In the drawings: 
The reference numeral 10 indicates an internal combustion engine having an 
exhaust manifold 12 connected with a supercharger 14 by an exhaust pipe 
16. The output of the supercharger 14 is connected with the engine intake 
manifold 18. The waste gate, indicated generally at 20, is preferably 
connected with the exhaust pipe 16 on the outside of a curve or bend 22 in 
the exhaust pipe for the reasons presently explained. The waste gate 20 is 
connected with the intake manifold by a tube 24 for opening and closing a 
valve in the waste gate in the manner presently explained. 
The numeral 26 indicates a waste gate housing having a generally 
elbow-shaped base portion 28 having flat faces 30 and 32 arranged in right 
angular relation and provided with an elbow-shaped gas passageway 34 
forming an inlet port 36 open through the face 30 and an outlet port 38 
open through the face 32. The inlet port is counterbored, as at 37, for 
the reason presently apparent. The housing 26 further includes a 
cylindrical portion 40 having a bore 42 formed on an axis coaxial with the 
inlet port 36 with the cylindrical portion 40 being secured to the base 28 
by a web portion 44 having a transverse aperture 46 open to opposing sides 
of the web and communicating with the adjacent end of the cylindrical bore 
42. The housing 26 further includes a generally dish-shaped diaphragm 
supporting plate 48 integrally joined with the cylindrical portion 40 and 
lying in a plane parallel with and diametrically opposite the base face 
32. A ring member 50 is flatly secured to an outstanding flange 52 formed 
on the diaphragm plate 48 by screws 54. An imperforate diaphragm 58 is 
interposed between the ring 50 and flange 52 to complete a pressure 
sensitive chamber 56. 
A tubular hose fitting 59 is threadedly connected with a boss 60 formed on 
a peripheral portion of the diaphragm plate 48 and communicates with the 
pressure chamber 56 through a bore, not shown, formed in the boss 60. The 
tube 24 is connected with the fitting 59 in a conventional manner. 
The base face 30 is connected with a fitting 62 by bolts and nuts 64 
extending through the base 28 outwardly of the elbow-shaped passageway 34. 
The fitting 62 is interposed in the exhaust pipe on the outside curved 
surface of the exhaust pipe curve 22 so that maximum exhaust gas flow is 
directed into the fitting 62 for selective release, as presently 
explained. 
The housing base 28 is drilled coaxial with the axis of the cylinder bore 
42 for receiving a valve stem guide bushing 66 which extends into the 
passageway 34 from the transverse opening 46. The bushing 66 slidably 
receives the stem 68 of a valve having its head 70 substantially coaxially 
disposed within the inlet port 36. A washer 72, having a valve seat 74, is 
loosely disposed within the inlet port counterbore 37 for cooperative 
mating with the valve seat 76. The loose fit of the washer 72 within the 
counterbore 37 permits the valve head 70 to center the washer coaxial with 
the axis of the valve stem to insure contiguous contact of the seats 74 
and 76 and closing of the inlet port 36. A valve cap 78 is secured in a 
substantially conventional manner to the end of the valve stem opposite 
its head. A valve loading spring 80 bears against the valve cap 78 at one 
end and coaxially extends at its other end into the cylindrical bore 42. A 
plug 82 is coaxially received by the cylindrical bore 42 at its end 
opposite the valve and is held in place by set screws 84 extending through 
the wall of the cylinder portion 26 and into diametrically opposite 
sockets 86 formed in the plug 82. The plug 82 is coaxially bored and 
threaded for receiving a spring tension adjustment bolt 88 which contacts 
a thrust bearing, such as a ball bearing 90, contained by a valve spring 
cap 92. 
A bell crank 94 is pivotally supported by a pin 96 extending transversely 
through a housing projection 98 for pivoting movement of the bell crank 
arms 100 and 102 about the axis of the pin 96. The crank arm 100 extends 
toward the axis of the diaphragm plate 48 and is provided with a threaded 
bore 104 which receives an adjusting screw 106 coaxially bearing against a 
disk 108 of smaller diameter than the diaphragm ring 50 which contiguously 
overlies and contacts the diaphragm 58. The other crank arm 102 underlies 
the valve cap 78 so that when the spring 80 biases the valve to a closed 
position the other crank arm 100 moves the diaphragm 58 toward the 
diaphragm plate 48 so that the chamber 56 is at a minimum capacity. 
A tube-like exhaust fitting 110 is secured to the housing base face 32 by 
stud bolts 112 in a conventional manner for releasing exhaust gases, as 
presently explained. Obviously, the exhaust outlet port 38 and housing 
face 32 may be connected with an exhaust pipe communicating with a 
muffler, not shown, if desired. 
OPERATION 
In operation the waste gate 20 is connected with the fitting 62 and intake 
manifold tube 24, as described hereinabove. The valve spring 80 is 
normally under sufficient tension to maintain the valve head 70 seated 
thus closing the inlet port 36. The tension on the valve spring 80 is 
further adjusted by the adjusting bolt 88 in accordance with the fuel 
being used and operating characteristics of the engine. This is 
accomplished by listening to cylinder ignition while the engine is running 
and adjusting the valve spring tension so that when pressure builds up, 
beyond a desired maximum, in the engine intake manifold, at a selected 
speed of the engine, it is applied to the diaphragm chamber 56 thus 
biasing the diaphragm 58 and crank arm 100 outwardly from the plate 48. 
The crank arm 102 is then lifted against the valve stem cap 78 to compress 
the spring 80 and unseat the valve head 70 to release exhaust gas pressure 
through the passageway 34. Thereafter, at lower engine speeds, the valve 
head 70 remains seated. 
Obviously the invention is susceptible to changes or alterations without 
defeating its practicability. Therefore, I do not wish to be confined to 
the preferred embodiment shown in the drawings and described herein.