Nozzle and a device for the use of a nozzle of this type

A nozzle and a device for the application of the nozzle are disclosed. In the nozzle a mechanism is provided so that the dimensions of the hole for the flow of fluid can be varied according to the pressure differential between the inlet and the outlet. The above can be applied to the making of nozzles and/or devices, the delivery rate of which is directly proportionate to the differential pressure between the inlet and the outlet.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention pertains to a nozzle, namely a part that is designed to be 
placed in a hydraulic or pneumatic system and having a hole calibrated to 
limit or regulate the delivery of the fluid flowing in the system. It also 
pertains to a device for the application of a nozzle of this type. 
2. Description of the Prior Art 
There are nozzles in the fuel-injection devices of engines or in jacks or 
valves or else, again, in certain devices for dampening the vibrations to 
which any elements or systems may be subjected, or which may be produced 
by these elements or systems. 
However, the nozzles used in these various applications have the 
disadvantage of having a delivery rate which is proportionate to the 
square root of the pressure differential existing between the inlet and 
the outlet of the calibrated hole. More precisely, the delivery rate is 
proportionate to the product of the square root of the pressure 
differential by the area of the hole. This particular feature may be 
troublesome in certain cases, especially when it is sought to obtain a 
specific delivery rate at the outlet of the nozzle by using it in a loop 
for the regulation of the delivery rate. For, in this precise instance, if 
it is sought to double the delivery rate with respect to a given value, 
the pressure differential corresponding to the value must be multiplied by 
4. This means, for example, that if the outlet hole of the nozzle is in a 
zone having a constant pressure, the inlet pressure must be made to vary 
in order to cause a variation in the delivery rate. It also means that if 
the outlet pressure is small compared to the inlet pressure, it is 
necessary to multiply the inlet pressure practically by a factor of 4 to 
double the outlet delivery rate. 
In a case of this type, the pressure needed at the inlet of the injector 
varies almost exponentially, and when the values become high, great 
variations are necessary in the inlet pressure to obtain appreciable 
variations in the delivery rate. Now the inlet pressure is given by means 
placed upstream of the hydraulic or pneumatic circuit, and the result of 
this is that the energy needed to actuate these means also varies almost 
exponentially. Since the efficiency of the said means is not perfect and 
is not constant along its entire range of use, the relative difference 
between the energy given to these means and the energy that they produce 
is all the greater as the delivery rate and/or input power values diverge 
from the rated value which can be given by the said means. 
The nozzle of the invention does not have these disadvantages. 
According to the invention, a nozzle comprises means so that the dimensions 
of the hole for the flow of fluid vary according to the pressure 
differential existing between its inlet and its outlet. 
According to another characteristic of the invention, the nozzle has a flat 
part through which at least two cuts are made, defining at least one 
tongue designed to be placed in the path of the fluid and capable of being 
deflected elastically when there is a pressure differential between its 
two sides. 
According to another characteristic of the invention, when there is no 
pressure differential on either side of the tongue, its main plane and the 
plane of the flat part on which it is made are identical and, when there 
is a pressure differential, the tongue is deflected towards the zone where 
there is low pressure. 
Consequently, when the tongue or tongues are in the idle position, the hole 
for the flow of fluid is at its minimum size. The area of the said hole 
then corresponds to the total area of the cuts made in the flat part. When 
the pressure differential increases, the tongue or tongues are deflected 
and the cross-section of the fluid passage also increases. The delivery 
rate is therefore greater than the delivery rate that would have been had 
if the cross-section had not undergone variation. 
In one embodiment of the nozzle, the cuts are made in such a way that at 
least one part of the delivery rate curve as a function of the 
differential pressure is linear, the delivery rate in this part being 
directly proportionate to the differential pressure between the inlet and 
the outlet. 
SUMMARY OF THE INVENTION 
The main object of the invention is a nozzle comprising a flat part through 
which at least two cuts are made, defining at least one tongue which is 
designed to be placed in the path of the fluid and is capable of being 
elastically deflected, thus increasing the cross-section of the fluid 
passage when there is a pressure differential between its two sides, 
nozzle wherein each cut comprises two grooves that are parallel to each 
other, one on each of the sides of the flat part, and also comprises a 
slit of the same length as the grooves.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 shows the curve Q(dp) of the delivery rate Q of a prior art nozzle 
as a function of the pressure differential dp between its inlet and its 
outlet. 
In a nozzle of this type, the expression of the delivery rate Q has the 
form Q=k.S.dp where k is a coefficient which is related, in particular, to 
the nature of the fluid flowing in the system and S is the cross-section 
of the nozzle hole. It can be seen that the slope of the curve diminishes 
with distance from its starting point, i.e. when the pressure differential 
increases. This means that, if it is desired to use a nozzle of this type 
as a delivery rate regulator, it becomes increasingly difficult to 
regulate the delivery rate when the pressure differentials are high 
between the inlet and the outlet. 
FIGS. 2a and 2b show two views of a prior art nozzle for which the delivery 
rate curve Q as a function of the pressure differential dp between the 
inlet and the outlet is that of FIG. 1. FIG. 2b is a section view along AA 
of FIG. 2a. 
The nozzle comprises, for example, a flat part 21 placed in the circuit of 
the fluid flowing in the hydraulic or pneumatic system. This part of the 
circuit is, for example, a pipe 22. 
The effective part of the nozzle is a hole 23, made through the flat part 
21 placed in the pipe. The delivery rate depends on the cross-section of 
this hole and is, therefore, proportionate to the square root of the 
pressure differential (Pe-Ps) between the inlet and the outlet of the 
nozzle. 
FIGS. 3a and 3b show an embodiment of the nozzle according to the 
invention, which makes it possible to resolve the problems raised by prior 
art nozzles. FIG. 3b is a cross-section view along AA of FIG. 3a when a 
flow of fluid is established. 
The nozzle consists essentially of a flat part 30, provided with two 
tongues 31, 32 which are deformable by elasticity when a pressure is 
exerted on one of their sides. These two tongues are obtained by making 
three cuts 33, 34, 35 in the flat part. Two of the cuts 33, 34 are 
parallel to each other, and the third cut 35 is perpendicular to them and 
joins their midpoints. Thus, in a top view (FIG. 3a), the cuts have the 
shape of an H and the two tongues 31, 32 are opposite each other. 
When the difference between the input pressure Pe and the output pressure 
Ps of the nozzle becomes sufficient to overcome the elastic strength of 
the tongues, these tongues are deflected and the hole, which initially had 
the section of the cut, increases its section. Thus, for a given pressure 
differential, the delivery rate is greater to that which would have 
existed if the cross-section of the hole were to remain constant. 
FIG. 4 shows an alternative embodiment in which there is also provision for 
making four triangular-shaped tongues, 41, 42, 43 and 44 on a flat part 
40. These tongues are obtained, for example, by making two cuts 45, 46 
which intersect at their middle point. 
Preferably, as FIG. 4 shows, the cuts 45, 46 are of equal length and are 
perpendicular to each other. Thus, in this case, the four tongues have the 
same shape and area. However, the number of tongues can be increased by 
increasing the number of cuts and by making them intersect, preferably at 
equal angles. 
As in the previous case, when the pressure differential becomes greater 
than the lower threshold of deflection of the tongues, the cross-section 
of the fluid passage increases. 
FIGS. 5a and 5b show two views of another alternative embodiment, FIG. 5b 
being a cross-section view along AA of FIG. 5a when there is a pressure 
differential. 
The rectangular-shaped tongue 51 has been made also in a flat part 50 by 
making three cuts 52, 53, 54 in this said flat part. Two of these are 
parallel with each other, and the third cut joins one end of each of the 
first two cuts. 
As can be seen in FIG. 5b, the tongue 51 is also deflected when the 
pressure differential becomes sufficient to overcome its lower threshold 
of deflection, and the cross-section of the hole for the flow of fluid 
then increases as and when the pressure differential increases beyond this 
threshold. 
The various embodiments that have just been described make it possible to 
obtain, for a pressure differential greater than the lower threshold of 
deflection of the tongues, a delivery rate which is greater than that 
which would have been obtained if the hole for the flow of fluid were to 
keep a constant cross-section. Consequently, the energy needed to increase 
the delivery rate by a given value in these types of nozzles is smaller 
than that needed in prior art nozzles, and nozzles according the invention 
are therefore easier to use than those of the prior art. 
FIGS. 6a and 6b show two distinct views of the preferred embodiment of a 
nozzle according to the invention, FIG. 6b being a cross-section view 
along AA of FIG. 6a which can also be applied to the cuts described in the 
previous figures. 
This nozzle also comprises a flat part 60 in which a single triangular 
tongue 61 is made. For this, two cuts 62, 63 forming an acute angle with 
each other and having a common end are made in the flat part 60. 
In order to fix the nozzle to its surrounding elements, at least two holes 
64, 65, are provided near the edges of the flat part 60 to enable the 
passage of screws or parts having the same function. Other fixing means 
can be considered. 
Similar holes or equivalent means have not been shown in FIGS. 3a, 4, 5a 
which show the other embodiments. However, it is clear that they are also 
necessarily present in these figures. 
The cuts 62, 63 are straight as can be seen in FIG. 6a and, in the 
thickness of the flat part, they preferably have the shape shown in FIG. 
6b. 
Each cut connects the two mutually parallel main sides 66, 67 of the flat 
part 60 and comprises two grooves 68, 69, one on each side, connected by a 
slit 610. 
Preferably, the longitudinal axes of the grooves 68, 69 are parallel to 
each other. Preferably, the said axes are borne on one and the same plane 
perpendicular to the two sides 66, 67 and the longitudinal axis of the 
slit 610 which joins the two grooves is parallel to them. 
In a preferred embodiment, the grooves 68, 69, have a milled shape as can 
be seen in FIG. 6b. For this, each groove 68, 69, has three distinct 
walls, two of them forming its sides, which are symmetrical with a plane 
perpendicular to the axes, and the third wall forming its bottom. 
Between the walls forming the sides of the groove, there is a determined 
acute angle which is preferably greater than or equal to 45.degree.. The 
wall forming the bottom is rounded and the slit 610 joining two grooves 
68, 69, ends in the middle of this wall forming the bottom. Thus, this 
wall forming the bottom consists of two rounded half-walls separated by 
the joining slit 610. The slit has the same length as the grooves. 
It is clear that the special slits and grooves that have just been 
described for the nozzle with a triangular tongue can be made on the types 
of nozzles described earlier within the framework of this invention. 
The embodiment with a triangular tongue made between two cuts, each 
consisting of two grooves with a milled shape, joined by a slit, has 
additional advantages as compared with the other embodiments described 
later. For they make it possible to obtain a delivery rate curve as a 
function of the differential pressure which is linear in at least one part 
of its working range. 
This curve is shown in a solid line in FIG. 7, under the reference 71. 
Another curve 72 is shown in a broken line. This is the characteristic 
curve of prior art nozzles. 
The curve 71 of the preferred embodiment of the nozzle of the invention has 
been shown in three parts A, B, C, each having a different curve. 
The part A, at the start of the curve, between the starting point and a 
pressure differential d1p, corresponds to the interval during which the 
tongue 61 undergoes no deflection, for the pressure differential values do 
not reach the lower threshold of deflection of the tongue. For this part 
A, the curve has the shape of a curve for a prior art nozzle since the 
cross-section of the hole remains constant. 
Thus, if a prior art nozzle which gives the curve 72 has a hole for which 
the constant cross-section is equal to the cross-section of the hole of 
the nozzle according to the invention before the tongue has started being 
deflected, it is observed that the part A of the curve 71 of the nozzle of 
the invention is the same as the start of the curve 72. The part B of the 
curve 71, between the pressure differential values d1p and d2p, is the 
linear part. In this part of the curve, a variation of the delivery rate Q 
is directly proportionate to a variation of the pressure differential. 
This characteristic is especially valuable because a nozzle of this type 
can be used in a delivery rate regulating loop in a very simple way, by 
making it work in this linear part for, in this case, the associated 
servo-control or control elements are easier to use. 
The part C of the curve 71 is the one that can be observed from the moment 
when the tongue 61 has reached its maximum deflection. In this case, the 
hole for the flow of fluid becomes constant and the delivery rate becomes 
proportionate to the square root of the pressure differential. In the 
example shown, the tongue reaches its maximum deflection for the pressure 
differential d2p. 
It is clearly understood that curve of the delivery rate Q as a function of 
pressure differential dp, existing between the inlet and the outlet of the 
nozzle, depends essentially, on the one hand, on the material used to make 
it, and, on the other hand, on the initial cross-section of the hole i.e. 
the cross-section of the cuts. 
For the deflection starts all the more quickly as the initial cross-section 
is small and as the elasticity of the tongue is great. By acting on these 
parameters, the part A of the curve 71 can be reduced or, on the contrary, 
accentuated, depending on the use envisaged for the nozzle. 
Preferably, a nozzle having a triangular tongue 61 consists of a flat 
circular part 60 made of steel. 
In this embodiment, the flat part 60 has a diameter of 16 mm. and its 
thickness is about 1 mm. The two cuts form an angle of about 30.degree. 
between each other and are about 10 mm. long. Between the walls forming 
the sides of each groove 68, 69 there is an angle of about 90.degree., and 
the radius of curvature of the wall forming the bottom is about 0.15 mm. 
The slit 610, that joins the bottoms of the two grooves forming a cut, is 
0.1 mm wide and 10 mm long while the total depth of a groove between a 
side 66, 67 of the flat part and the intersection of a groove with a slit 
610 is about 0.45 mm. 
Preferably, the nozzles are made of steel and the grooves and slits are 
machined by electroerosion in every type of nozzle according to the 
invention. Furthermore, a trueing treatment for the sides is done after 
the grooves and the slits have been made. 
FIGS. 3a, 4, 5a and 6a have a double arrow indicating, as the case may be, 
the main direction of the fibers of the constituent material of the 
nozzles. It is thus seen that the axis of deflection of the tongues, shown 
in certain figures by a thin line, joining the free ends of two slits, 
always forms an angle equal to at least 45.degree. with the main direction 
of the fibers, firstly so that the elasticity of the tongues is sufficient 
and, secondly, to prevent the risk of breaks along the fibers. 
FIGS. 8 and 9 pertain to an embodiment of a device comprising at least two 
nozzles according to the invention. The association of at least two 
similar nozzles can be used to obtain a different resultant curve, hence a 
curve with different characteristics. 
FIG. 8 shows an exploded view of a device comprising three nozzles made 
according to the preferred embodiment of the invention. 
These three nozzles each have a flat part, 81, 83, 85 and a tongue 810, 830 
and 850. To enable the deflection of the tongues, interposed parts are 
provided to separate two neighboring tongues. Each interposed part 
consists of flat part 82, 84 with a window 820, 840 drilled through it. 
This window lets a tongue go through it when this tongue is deflected. 
When there are no such interposed parts, two neighboring nozzles will be 
attached by their sides and it will not be possible for the deflection of 
the tongues to take place. 
Furthermore, at least two holes 811, 812, 821, 822; . . . 851, 852 are 
provided in each nozzle and each interposed part, to enable the fixing of 
these various elements with one another and with the associated hydraulic 
or pneumatic system, using appropriate means not shown in the figure. 
These means may be screws, studs or any other equivalent parts fulfilling 
the same function. 
Preferably, as can be seen in FIG. 8, when the device has at least two 
identical nozzles, they are placed parallel to each other, but the tongues 
are not pointed in the same direction. In the embodiment of FIG. 8, two 
neighboring tongues are offset by 180.degree. with respect to one another. 
This arrangement provides for the optimum distribution of stresses on the 
structure during operation. 
The windows made in the interposed elements have at least one straight side 
designed to be positioned so that its perpendicular projection in the 
plane of the associated nozzle passes through the free ends of the slits. 
Consequently, when a nozzle is fixed between two interposed elements, the 
straight side of the window of each these two interposed elements faces 
the axis of deflection and the movement of the tongue is perfectly 
controlled. In order to enable an angular offset between two neighboring 
tongues, separated by an interposed element, the window of the interposed 
element should have at least two straight sides, and to enable an 
180.degree. offset, these two sides should be opposite and parallel to 
each other. 
In FIG. 8, the windows are square shaped and the projections of their sides 
on the nozzles are shown in broken lines. The nozzles are offset by 
180.degree., but the square shape enables an offset of 90.degree. between 
two nozzles. 
In one embodiment, not shown, the windows are rectangular and this suffices 
to make offsets of 180.degree. by using the small side of the rectangle as 
the support of the axis of deflection. 
The use of at least two identical nozzles makes it possible to increase the 
pressure differential while, at the same time, obtaining one and the same 
delivery rate, or else, to reduce the delivery rate while having the same 
pressure differential as with only one nozzle. 
FIG. 9 shows a first curve 91 of the delivery rate Q as a function of the 
pressure differential dp of a nozzle according to the preferred 
embodiment. This first curve 91 faces a second curve 92 of the delivery 
rate Q of a device formed by the association of at least two nozzles 
according to the preferred embodiment, each having identical 
characteristics or similar characteristics to those given by the first 
curve 91. 
It is observed, from these curves, that a single nozzle gives a delivery 
rate Q1 for a pressure differential of d3p, whereas a device consisting of 
at least two identical nozzles gives the same delivery rate Q1 for a 
pressure differential of d4p greater than the pressure differential d3p. 
Furthermore, it is observed that one and the same pressure differential d5p 
corresponds to a delivery rate Q2 of the device which is lower than a 
delivery rate Q3 of a single nozzle. 
The association of at least two identical nozzles therefore makes it 
possible to obtain a device having pre-set characteristics with great 
flexibility. 
It is generally possible to associate different nozzles, the curve of each 
one of them being known, to obtain a determined value. The invention is 
therefore especially advantageous since it provides for making devices 
having a transfer function that can be easily calculated.