GAS CONTROL VALVE

ROBINET REGULATEUR DE DEBIT DE GAZ

English Abstract

ABSTRACT OF THE DISCLOSURE
There is disclosed a gas pressure control valve
that is pressure balanced so that the torque required to
operate the valve is independent of the internal pressure
of the valve. A control piston within the valve body is
subject to pressure, which is balanced by a bore through
the piston to a pressure chamber through which the fluid
under pressure may move so that gas pressure acting on
one end of the piston is balanced by the gas pressure in
the pressure chamber at the opposite end of the piston.
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Claims

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined as
follows:
1. A fluid valve comprising a valve body, a
piston slidable in a cylindrical bore in the body, means
for moving the piston, and a fluid passage extending from
a fluid inlet to a fluid outlet via the piston, movement
of the piston controlling the flow of fluid through the
passage, one end of the piston being within the passage
and subject to pressure of fluid in the passage, a
pressure chamber at the end of the piston opposite to the
one end, and a passage extending from the one end of the
piston to the pressure chamber at the opposite end
whereby the pressure acting on the piston at the one end
is balanced by the pressure at the opposite end to reduce
the force required to move the piston between open and
closed positions.
2. A fluid valve as claimed in claim 1
wherein the fluid passage extends from a side of the body
via an annular recess in the piston to an area adjacent
the one end of the piston, the recess being tapered from
its widest portion toward said one end of the piston, the
cylindrical bore being counterbored and thus widened to
define a valve seat surrounding the one end of the
piston, the valve seat being adjacent the annular recess,
whereby the coacting taper and valve seat vary the size
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of the opening of the valve with movement of the piston.
3. A fluid valve as claimed in claim 2
wherein the one end of the piston is widened to define a
crown, wider than the bore, slidable with counterbore.
4. A fluid valve as claimed in claim 1 or 2
or 3 wherein the ends of the piston are recessed to
reduce its weight.
5. A fluid valve as claimed in claim 2
wherein the means for moving the piston comprise a lever
mounted on a shaft journalled in the valve body, the
lever end engaging a recess in the piston to effect move-
ment of the piston.
6. A fluid valve as claimed in claim 5
wherein the taper of the recess is curved to vary the
rate of the valve opening.
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Description

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6613-~
This invention relates to a fluid valve, espe-
cially for gases. It is especially useful Eor gas supply
control in internal combustion engines.
There is frequently a need in the fuel supply
for internal combustion engines for control of the rate
of flow o gases, for example to the cylinders of the
engine in a dual fuel engine. Often, the power available
to move such valves is very limited. The present inven-
tion provides a gas control valve so constructed that the
power required to move a valve element is very small.
According to the invention, there is provided
a fluid valve comprising a valve body~ a piston slidable
in a cylindrical bore in the body, means for moving the
piston, and a fluid passage extending from a fluid inlet
to a fluid outlet via the piston, movement of the piston
controlling the flow of fluid through the passage, one
end of the piston being within the passage and subject to
pressure of fluid in the passage, a pressure chamber at
the end of the piston opposite to the one end, and a
passage extending from the one end of the piston to the
pressure chamber at the opposite end whereby the pressure
acting on the piston at the one end is balanced by the
pressure at the opposite end to reduce the force required
to move the piston between open and closed positions.

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PreEerably, the Eluid passage extends ~rom a
side of the body via an annular recess surrounding the
piston to an area adjacent the one end of the piston.
The recess may be tapered from its widest portion toward
the one end of the piston, and the cylindrical bore may
be counterbored and thus widened to define a valve seat
surrounding the one end o~ the piston. The valve seat
may be adjacent the annular recess, whereby the coacting
annular recess and valve seat vary the size of the
opening of the valve with movement o~ the piston.
The attached drawing illustrates an embodiment
of the invention.
In the drawing, valve body 10 has a cylinder or
bore 11 in which there is slidable a piston 12. A pair
of gas inlet passages 13, 13' supply gas under pressure
to a chamber 26. An annular recess 15 surrounds the
piston 12, and is tapered at 16; the taper may comprise
a curve as will be described below. The crown 17 of the
piston is widened at 18, with the widened portion being
slidable in a counterbore 27. The counterbore, with the
crown 17 o~ the piston 12, defines a pressure outlet
chamber 14.
Extending through the piston 12 is a bore 25.
At the end of the piston opposite to the crown 17 there
is a sealed pressure chamber 21.
Within the chamber 26, mounted on shaft 20 and

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secured thereto e.g. by a ~ey 30, there is a lever arm 19
which engages in a recess 28 in the side of the piston
12. Rotation of the shaft 20 moves the lever 19 to the
right, as shown in the Figure, to move the piston and
vary the flow of gas from chamber 13 past the plston into
the outlet chamber 14.
The piston may be recessed at 23, 24 to reduce
its weight. 0-rings are provided at 29 and 31 to seal
against gas leakage.
In the prior art that is absent the pressure
chamber 21, once the valve is opened the pressure of the
gas within the chamber 14 would act on the crown 17 of
the piston 1~ to resist movement of the piston. To com-
pensate for this, bearing in mind the limited torque
available at the shaft 20, the bore 25 supplies gas under
pressure to the pressure chamber 21 wherein the gas acts
on the end 22 of the piston to balance the pressure on
the crown 17. Thus the torque necessary to rotate the
shaft 20 is substantially reduced when compared with
other constructions not having the balancing feature~
The curve in the taper 16 on the piston is
designed primarily to provide a relatively "dead band"
for the start of the valve opening r leading smoothly into
a progressively greater opening that is designed to match
the maximum (full load) flow requirements of an engine.
The "dead band" provides stable governor control action

12;~0992
when Euel Elow requirements are small; i.e. a higher
ratio oE governor travel to fuel flow when fuel Elow is
low, as it is for light load.