close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2133510

код для вставки
Oct. 18, 1938.
G. E. A. HALLETT
U-TYPE TWO-CYCLE ENGINE
Filed Oct. 30. 1936
2,133,510
Patented Oct. 18, 1938
2,133,510
UNITED STATES PATENT OFFICE
2,133,510
U-TYPE TWO CYCLE ENGINE
George E. A. Hallett, Detroit, Mich., assignor to
General Motors Corporation, Detroit, Mich., a
corporation of Delaware
Application October 30, 1936, Serial No. 108,343
4 Claims. (Cl. 123-53)
This invention relates to so called U type two
cycle engines in which a pair of parallel cylinders will be closed and opened at the same time by
have a common combustion chamber, one of the the piston in its stroke movement.
Directly over the pocket the cylinder head is
cylinders being provided with inlet ports and the
5 other with exhaust ports opened and closed by stepped slightly so as to e?'ect almost complete
the pistons, towards the end of their power stroke closure and segregation of the pocket from the 5
and the beginning of their compression stroke. combustion chamber proper, when the exhaust
and inlet pistons are towards the end of their
The inlet and exhaust pistons move together in compression
stroke.
the same direction, but it is usual for the ex
A spark plug is provided in the cylinder head
10 haust piston to. have a slight lead on the inlet
piston.
to ?re the idling charge in the pocket, and a
In such an engine, any residual exhaust gases second spark plug may be placed in the most
which remain in the exhaust cylinder after the advantageous position to ?re the main part of
exhaust port has been closed on the compression the charge in the combustion chamber, at greater
15 stroke are carried upwards into the combustion loads and speeds other than idling.
The drawing shows the application of the in 15
chamber and are to some extent pumped into
vention to a U type 2-cycle engine.
the combustible charge in the combustion cham
In the drawing, Figure l is a part sectional ele
ber. The actual quantity so pumped and its in
?uence will depend on the amount of charge vation of the pistons, cylinders, and combustion
chamber. Figure 2 is a diagrammatic end view
20 admitted through the engine inlet ports, particu
larly when scavenging is effected solely by the
incoming combustible charge.
At low load, or when idling, when only a small
quantity of charge is admitted, the larger pro
25 portion of burnt gases remaining in the engine,
dilutes the combustible gases to the point where
it is di?icult to ?re the charge.
It is especially dif?cult to secure proper idling
with a small economical charge in an engine
30 having an ideal combustion chamber in other
respects, with a quench area over the exhaust
piston, due to the fact that burnt gases are
squirted from such a quench area into the idling
charge by the exhaust piston when the exhaust
;5 piston has a lead on the inlet piston and reaches
top dead center before the inlet piston.
The object of the present invention is a means
of providing for the segregation of a small idling
charge of fresh mixture away from the contami
0 nating in?uence of the burnt charge, and at a
point where it can be effectively ?red by the
igniting means, thus to maintain the engine in
operation without stopping, on smaller charges
' than has heretofore been possible for the reasons
’ aforegiven.
The above and other objects of the invention
will be apparent as the description proceeds.
According to the invention a step is provided,
forming a pocket in the head of the inlet piston,
on that side thereof farthest away from the ex
haust piston.
The inlet ports in the cylinder wall are stepped
in conformity with the step in the inlet piston
so that all the ports in the inlet cylinder wall
showing the pistons and their connecting rods to 20
the crank shaft. Figure 3 is a view on line 3--3
of'Figure l to a reduced scale.
In the drawing, the cylinder block I is pro
vided with a cylinder 2, having inlet ports 3 and
a cylinder 4, having exhaust ports 5, these ports
being controlled respectively by pistons 6 and 1. 25
A pocket 8 is formed by a stepped down portion
in the head of the inlet piston 6.
The cylinder head 9 has a combustion cham
ber l0, common to the two cylinders 2 and 4, 30
there being a quench area ll over the exhaust
piston 1, and a slightly stepped down portion ll
of the cylinder head forming a lip cooperating
with the stepped down portion in the inlet piston,
to effect segregation of a part of the fresh charge
in the pocket 8, more or less separated from the 35
combustion chamber proper, when the exhaust
and inlet pistons are at'the end of their com
pression stroke.
I3 is a spark plug for igniting the charge in the
pocket 8, while the spark plug I4 is advantageous 40
ly placed for igniting the main part of the charge
in the combustion chamber at higher loads and
speeds.
It will be noted that the inlet ports 3 are stepped 45
to conform with the irregular contour of the head
of the inlet piston 6.
The pistons 6 and 1 are shown in a position
corresponding to the top dead center position of
the piston ‘I, the piston 6 not having yet reached 50
this position. It can clearly be seen that in this
condition the exhaust piston will be compressing
and squirting some of the contents of cylinder 4
from the quench area H across the combustion
chamber. Without the pocket 8, and when, as 55
2
2,133,510 '
in idling, the contents of cylinder 4 being mainly
burnt gases and only a small quantity of fresh
charge having been admitted into cylinder 2,
these burnt gases would disperse and dilute the
fresh charge to an extent making it very diffi
cult if not impossible to ignite. The pocket 8,
on the other hand, in conjunction with the lip
l2 of the cylinder head, effectively segregates part
or the whole of the idling charge from the main
portion of the combustion chamber, the lip l2,
to segregate the small idling charge away from
the diluting in?uence of the burnt gases com
pressed into the combustion chamber by the ex
haust piston, and a spark plug in the cylinder
head, to enter the pocket as the inlet piston
reaches the end of its compression stroke, to
?re the idling charge
2. The combination according to claim 1 in
which the inlet ports in the cylinder wall are
stepped in conformity with the step in the inlet 10
piston, so that all the ports in the inlet cylinder
de?ecting away from the pocket 8, the burnt gases will be closed and open at the same time by the
squirted across the combustion chamber from inlet piston in its stroke movement.
the quench area I l by the exhaust piston fl.
3. The combination according to claim 1, in
which the combustion chamber has a quench area 15
I claim:
1. In a U type two cycle engine having a cylin
over ,the'exhaust piston, and the lip on the‘ cylin
der head with a combustion chamber common to der head serves to de?ect away from the pocket,
two cylinders respectively provided with inlet and
exhaust ports, an inlet piston ,in the inlet cylin
der and an exhaust piston in the exhaust cylin
20
the burnt gases squirted across the combustion
chamber from the quench area, by the exhaust
piston, as it approaches the end of its compres
der, a pocket formed by a step in the head of
stroke.
the inlet piston, on that side thereof ‘farthest sion
f1. 'rljhe combination according to claim 1 hav
away from the exhaust piston, said pocket co ing a secondsparkplu" in th'elcombustion cham
operating with the inlet ports to‘ carry a small
idling charge of freshrmixture towards the com
ber, at a ,‘point remojed from ithelpocket tame
busrtion chamber on the compression strokemove
2.5 merit ‘of the inlet piston, .a lip on the cylinder
head coacting with the pocket as vthe inlet piston
approaches the end of its compression stroke,
chamber at vgreater loads and “speeds other than
the main part of the charge in }the combustion
idling.
,
GEORGE
c
,
E. . A. neLLETT.
,
_
.
25
Документ
Категория
Без категории
Просмотров
0
Размер файла
281 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа