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Патент USA US3079872

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March 5, 1963
Filed Nov. 7, 195a
GYM?“ Qvm/
United States Patent 0
Patented Mar. 5, 1963
iliary cylinder 33 through an inlet opening 34. The
beginning of injection takes place when the edge 24 of
piston 5 comes to shut off intake port 61. The liquid
is placed under pressure and driven by piston 1 through
the distributing groove 4. The end of injection is pro
Jean Pierre Raihaud, Le Kremlin-Bicetre, France, assignor
to Society “Precision Mecanique Lahinal,” Saint-Galen,
duced by discharge (R) when the edge 25 of piston 5
France, a society of France
Filed Nov. 7, 1958, Ser. No. 772,469
4 (Iiaims. (Cl. 103-41)
The present invention relates to piston pumps, more
especially for the injection of fuel into internal com
comes to uncover port 71 and places it in communication
‘with groove 26 and conduit 15. Auxiliary piston 5 is
reciprocable in an auxiliary cylinder formed in the pump
body and ending in a space 27.
The displacement of piston 5 is obtained by hydrody
namic effect under the action of a piston 16 rigid with
piston 1 and cooperating with a feed cylinder formed
in the main pump body, the variable volume chamber
bustion engines, of the kind in which the conditions of
delivery to the utilisation devices or apparatus (injectors
or the like) are adapted to be modi?ed by the action 15 limited by piston 16 in its cylinder being connected
through a conduit 17 with space 27.
of at least one auxiliary piston acting as a slide valve
In this conduit 17, there is provided a check valve
cooperating with intake and/ or discharge ports, said aux
A discharge or return circuit 2?, 3% is provided
iliary piston being actuated in suitable manner in ac
between space 27 and the cylinder of piston 16, this
cordance with the displacements of the main piston.
The object of the present invention is to provide ‘a 20 circuit including a throttled passage x which is advanta
geously controlled by a pilot valve 22 or any other
pump of this kind in which the beginning of fuel injec
tion is advanced with respect to the cycle of operation
It will be seen that, at low speeds, the throttled sec—
of the pump in response to an increase of the speed of
x has practically no effect. When piston 16 is driven
operation of the pump.
into its cylinder, piston 5 is lifted upwardly to perform
For this purpose, according to the present invention,
its distributing action. During the return movement of
the auxiliary piston is movable in a corresponding aux
piston 16, valve 23 closes so that the liquid, under the
iliary cylinder in response to the delivery strokes of the
effect of the downward movement of piston 5 produced
main piston of the pump in its cylinder, the return strokes
by its spring 12, is compelled to escape from chamber
of said auxiliary piston being produced by resilient means
and the liquid discharged from said auxiliary cylinder 30 27 through the return circuit 29, 30 (discharge r). The
throttled passage x exerts practically no effect so that the
during the return strokes of the auxiliary piston being
slide valve can return to its lowest position.
made to ?ow through a throttled passage so that for
On the contrary, when the speed increases, the relative
speeds of operation of the pump above a given value a
eifect of the throttled passage as becomes more and more
portion of this liquid no longer has time to flow out
from said auxiliary cylinder through said throttled pas 35 important so that the auxiliary piston is braked during
its downward movement and can no longer return to its
sage during the return strokes of the auxiliary piston,
lowest position. This produces an automatic advance
which are thus shortened so as to advance the beginning
of the beginning of injection in response to an increase
of fuel injection.
A preferred embodiment of the present invention will 40 of the speed.
be hereinafter described with reference to the accom—
panying drawing, given merely by way of example and
in which:
The only FIGURE shows, in diagrammatic axial sec
tion, a pump made according to the present invention
for use as a fuel feed pump for an internal combustion
The pump illustrated by the drawing includes at least
one main piston 1 ?tting slidably in a main cylinder 31
so as to form therewith a variable volume chamber 32,
this piston 1 being capable of feeding fuel successively
to several delivery conduits such as conduit 2 leading
to injector 3, said piston having, for this purpose, in
If necessary, the throttied section at may itself be ad
justed as a function of the speed or of another param
eter. On the drawing, valve 22 has been shown as being
controlled by a centrifugal governor 23.
In a general manner, while I have, in the above de
scription, disclosed what I deem to be practical and
e?icient embodiment of my invention, it should be well
understood that I do not wish to be limited thereto as
there might be changes made in the arrangement, dis
position and form of the parts without departing from
the principle of the present invention as comprehended
within the scope of the accompanying claims.
What I claim is:
addition to its reciprocating movement, a movement of
continuous rotation (see arrow F) to ensure distribution
to said conduits through a lateral groove such as 4.
1. A reciprocating piston liquid pump which com
prises, in combination, a main cylinder and a reciprocat
ing main piston ?tting slidably in said cylinder so as
Auxiliary piston 5 (the angular position of which is
piston ?tting slidably in said auxiliary cylinder, hydraulic
to form therewith a variable volume chamber, the dis
There is further provided at least one auxiliary piston
placements of said piston with respect to said cylinder
5 acting as a regulating slide valve capable, by cooper
which reduce the volume of said chamber being called
ation with suitable ori?ces or ports, of modifying the
the delivery strokes of said piston, a delivery conduit
conditions of delivery. This auxiliary piston 5 ?ts slid
communication with said chamber, an auxiliary cylin
ably in an auxiliary cylinder 33 formed in the same body
der faxed with respect to said main cylinder, an auxiliary
as the main cylinder 31.
adjustable) includes distributing edges 24, 25, capable
of cooperating with two ports 61, 71, port 61 being a
fuel feed port in communication with a fuel tank and
port 71 a liquid discharge port. In the lower position
of auxiliary piston 5 as shown by the drawing, admis~
sion (A) takes place through port 61 opening opposite
an annular groove 26 of the slide valve, said groove be
ing itself connected to the variable volume chamber 32
of the pump through conduit 15 which opens into aux
means operatively connected to said main piston and
arranged to act on said auxiliary piston so that every
delivery stroke of said main piston causes a displace
ment of said auxiliary piston in one direction, resilient
means connected with said auxiliary piston for urging
it in the direction opposed to said ?rst mentioned direc
tion, said auxiliary cylinder and piston being arranged
to form between them a variable volume space which
increases during the displacements of said auxiliary pis
twin said ?rst mentioned direction and decreases dur
ing the displacements of said auxiliary piston in said
second mentioned direction, said last mentioned displace
ments of said auxiliary piston being called return strokes
thereof, a liquid feed .port opening into said. auxiliary
.‘cylinde'r ‘near one end vthereof, a liquid discharge port
in said auxiliary cylinder near the other end thereof,
said auxiliary cylinder being provided with an inlet open
ing located'at a point thereof intermediate between said
main cylinder, a feed piston rigid with said main piston
and ?tting slidably in said feed cylinder so as to form
therewith a variable volume feed chamber, a liquid 'feed
conduit opening into the pprtion of said feed cylinder
limiting said feed chamber, a conduit leading from said
portion of said feed cylinder to the portion of said aux
iliary cylinder limitingsaid variable volume space and
a check valve in‘ said last mentioned conduit arranged
ports, conduit means leading from said variable volume 10 to permit ?ow of liquid only from said feed’ chamber
toward said variable volume space.
chamber of said main cylinder to said auxiliary cylinder
3. A pump according to claim 1 in which said means
inlet opening, said auxiliary piston being in the form
for hydraulically connecting said auxiliary piston with
of va slide valve provided with a passage arranged to
said main piston include a feed cylinder rigid with said
connect said inlet opening with said feed port at the
beginning of .every movement of said auxiliary piston in 15 main cylinder, a feed piston rigid with said 'main piston
said ?rst mentioned ‘direction, then to cut oil? said inlet
opening from both of said ports for a portion of said
and ?tting slidably in :said feed cylinder so as to form
therewith a variable volume feed chamber, alliquid'feed
last mentioned movement and ?nally to connect said
conduit opening into the portion of said feed cylinder
inlet opening with said discharge port at the end of
limiting said feed chamber, a conduit leading from said
said last mentioned movement, and liquid discharge 20 portion of said feed cylinder to the portion of ‘said aux
means in ,communication,.during the return strokes of
iliary cylinder'limiting said variable volume space ‘and
said auxiliary piston, with the portion of said auxiliary
‘a check valve in said‘last mentioned conduit varranged
~cylinder limiting said variable volume space, said liquid
'to'permit flow of ‘liquid only "from said ‘feed chamber
discharge means forming the only way for the out?ow
toward said variable volume space, said liquid discharge
of liquid from said space during said return strokes of 25 means leading from ‘the portion of said auxiliary cylin
‘said auxiliary piston and said liquid discharge means
der limiting said variable volume space to the portion
including a throttled passage for braking the out?ow
of said feed cylinder forming vsaid feed chamber.
‘therethrough of ‘liquid from vsaid space, whereby, for
' 4. A pump according to claim .1 further comprising
speeds of reciprocation of said main piston above a given
means for varying the cross-section ‘area of
value, "said throttled passage in ‘said liquid discharge
said throttled passage and governor means responsive
means permits only a portion of ‘the liquid presentrin
during every return ‘stroke of said vauxiliary piston and
to variations of the speed of reciprocation of said main
piston for controlling said adjusting means in accord
thus limits said return stroke so that on the next de
ance with said speed variations.
‘said variable volume space to be discharged therefrom
livery-stroke of said main piston said conduit means 35
opening is cut oif'from ‘said liquid intake port at an
earlier time during every cycle of operation of'the pump.
'2. A pump according to claim 1 in which said means
for hydraulically connecting said auxiliary piston with
said main piston include a feed cylinder rigid with said
References Cited in the ?le'of this patent
Outin ______________ .... Apr. "28, ‘1942
Bessiere _____________ __ June '14, 1960
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