MOTEUR QUATRE TEMPS, AVEC DEUX SOUPAPES PAR CYLINDRE

FOUR STROKE ENGINE WITH TWO VALVES PER CYLINDER

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
The invention provides a four-stroke diesel engine
having two valves per cylinder, wherein each injector is located
in the cylinder head in such a way as to project at least three
jets of fuel in the direction of a combustion chamber formed
in a corresponding piston head, the eccentricity of each injector
in its cylinder being at most equal to 0.15 times the diameter
of the cylinder, the height of the combustion chamber formed
in the head of each piston being at least equal to 0.55 times
the maximum diameter of the chamber, the eccentricity of the
injector being defined as being the distance between the point
of intersection of the axis of the cylinder with the plane
containing the lower flat face of the cylinder head and the
point of intersection of the axis of the injector with the
same plane,the height of the chamber being defined as being
the greatest depth of the chamber measured parallel to the
axis of the cylinder, and the maximum diameter of the chamber
being the greatest diameter measured parallel to the lower
face of the cylinder head.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A four-stroke diesel engine having two valves per
cylinder, wherein each injector is located in the cylinder head
in such a way as to project at least three jets of fuel in the
direction of a cylindrical combustion chamber formed in a corresponding
piston head, the eccentricity of each injector in its cylinder
being at least equal to 0.15 times the diameter of the
cylinder, the height of the combustion chamber formed in the
head of each piston being at most equal to 0.55 times the
maximum diameter of the chamber, the eccentricity of the
injector being defined as being the distance between the
point of intersection of the axis of the cylinder with the
plane containing the lower flat face of the cylinder head and
the point of intersection of the axis of the injector with the
same plane, the height of the chamber being defined as being
the greatest depth of the chamber measured parallel to
the axis of the cylinder, and the maximum diameter of the
chamber being the greatest diameter measured parallel to the
lower face of the cylinder head.
2. A diesel engine according to Claim 1, wherein
each injector is eccentric in the corresponding cylinder by a
distance between 0.18 and 0.3 times the bore of the cylinder.
3. A diesel engine according to Claim 1 or Claim 2,
wherein each injector comprises at least three jets for which
the impact zones are distributed all around the corresponding
combustion chamber, these jets being distributed along a cone
of which the apex angle is greater than 90°.

Description

05~L
The present invention relates to a four-stroke engine ~
with two valves per cylinder. ~;
Known four-stroke diesel engines with two valves per
cylinder and with a combustion chamber incorporated in the
piston can be classifled into three main categories:
The first category which is practically obsolete
comprises a lateral injector remote from the centre and only
able to open into the piston chamber because of the use of
a piston having a head which is not flat or which includes an
inlet channel to the chamber which itself is not symmetrical.
Alternatively, an injector transfer channel to the chamber
situated in the piston is included in the cylinder head. The
combustion chamber is then not totally incorporated in the
piston.
The second and third categories provide the majority
o~ engines which are now manufactured inclustrially with the
chamber incorporated in the piston.
The engines of the second category have relatively
open, shallow combustion chambers in the piston head and
injectors relatively near to the axes of the cylinders, each
injector emitting several jets distributed around the periphery
of the correspondinc3 chamber.
The perEormAnce of khese en~Ji.nes is excellent, ~or
they give good output wlth A low fuel consumption over the
whole range of use, and lower temperatures in the critical zones;
they start well ;Erom cold, And give low pollution (liktle smoke)
exhaust.
On the other hand, each injec-tor is very near to the
inlet and outlet ~penings in the cylinder head, so that the
eorJ7 ~a c f
3~ cylinder head~leaving little room to provide sufficiently large
cooling water ducts.

~a~87~)5~L ~
The third category concerns enginès which are
referred to as having "parietal injection". These engines
carry in the piston heads relatively deep combustion chambers .:
wikh f~irly restricted throats which are generally symmetrical,
but sometimes include a small channel facilitating the
passage of the jets from the injector to the combustion chamber.
The injectors have jets directed in such a way as to spread :
over the surface of the combustion chamber, hence the term
".parietal injector".
Each injector may have a smaller number of jets than
the corresponding number for an engine of the second category
and in addition, it is, fairly remote from the centre of the
corresponding cylinder. ~.
These engines therefore have more accessible injectors,
which is advantageous for maintenance and repairs, and it is
easier to provide large passages in the cylinder head for the
flow o cooling water.
Accordlngly, the invention provides a four-stroke ;
diesel engine having two valves per cylinder, wherein
20 each injector is located in the cylinder head in such a way
as to project at least three jets of fuel in the direction
of a combustion chamber formed in a corresponding piston
head, the eccentricity of each injec-to.r in its cylinder being
at least equal to O.lS times the d.iameter o.E the cylinde.r,
the height oE the combustion chamber formed in the head of
~nos~
each piston being at 14a~ equal to 0.55 times the maximum
diameter oE the chamber, the eccentricity of the injector being
deined as beiny the distance between the point of intersection
of the axis of the cylinder with the plane containing the lower
flat face of the cylinder head and the point of intersection of
the axis of the injector with the same plane, the height of :
the chamber beiny defined as being the greatest depth of the
-- 2

5~
chamber measured parallel to the axis of the cylinder, and the
maximum diameter of the chamber being the greatest diameter
measured parallel to the lower face of the cylinder head.
~s the injector is generally inc].ined in relation to
the axis ofthe cylinder, its position in relation to the latter
demands accurate positioning of the intersection of its axis
with the lower flat face of the cylinder head, preferably, -~:
each injector has at least three jets of which the impact
zones are distributed all around the chamber, these chambers
forming a cone of which the apex angle is greater than 90.
The invention will now be descrlbed in more detail,
by way of example only, with reference to the accompanying : ....
drawings, in which:- :
Figure 1 is an axial section of an engine cylinder
according to the invention, and
Fiyure 2 is a plan view of the cylinder shown in Fic3ure 1.
In the clrawings, an engine cylinder comprises a liner 1
and a cylinder head 2 provided with avalve 3 mounted in an inlet
port, and a vaLve 4 mounted in an exhaust port and an iniector 5.
A combustion chamber 6 is defined within the head o
a piston 7 which slides vertically inside the cylinder. This
chamber 6 is toroidal, or cylindrical with a ~lat or curved
bottom, and has a maximumdiameter 8 and a maximum heigh-t or
depth 9.
The cylinder i~ bored to a diameter 10, and the
injector is eccentric by a distance 11 in relation to the
cylinder, the degree of eccentr.icity being defined as the
distance between the point of intersection of the axis of the
.~ cylinder with the plane containing the lower flat face of the
cylinder and the point of intersection of the axis of the
injector with the same plane.
The injector is designed to emit three jets of fuel 12

~87~
of which the zones of impact are distributed all around the
chamber 6 along a cone of which the apex angle is greater
than 90.
It can be seen that the described engine has a flat
piston and a symmetrical combustion chamber situated in the ~-
piston. The eccentricity 11 of the injector in the cylinder
is at least 0.15 times and should be between 0.18 and 0.3 times
the bore diameter 10 of the said cylinder for optimum
performance.
The maximum depth 9 of the combustion chamber 6 of the
piston head should be less than 0.55 times the maximum diameter
8 of the said chamber.
Tests have shown that this diesel engine has qualities
at least equal and sometimes superior to those oE an engine
with direct injection, as regards output, low consumption,
stArtiny or reduced pollution, whilst linking the performance
with a better distribution oE components in -the cylinder head.
In fact, the injector 5 is sufficiently far away from the
valves 3 and 4 for it to be possible to provide large cooling
channels for the flow of water and the injectors are.very
Accessible .
I'he ~cope oE the invention will not be exceeded by
u~lny in~cc~ors capable oE emtttincJ a numbex oE jets oE Euel
other than three, or by giving the axis oE the injectors a
larger or smaller inclination with regard to the axis oE each
cylinder.
I
1.
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