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Патент USA US2408706

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Oct. 1, 1946.
I
K, w, 'T‘ODD'
'
2,408,705
MECHANICAL RELAY OF THE FLUID JET TYPE
Filed Dec. 31, 1943.
Mi”;
2d.‘
FIG. 3.
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INVENTOR
KEITH" WATSON Tom) ~
ATTORNEYS
2,408,705
Patented Oct. 1, 1946
;IJ.UNITED_ STATES PATENT OFFICE
. Keith Watson Todd, Warrington, England, as
signor to Metropolitan-Vickers Electrical Com
pany Limited, London, England, a company of
Great Britain
Application‘ December 31, 1943, Serial No. 516,595.
In Great Britain May 28, 1940, and September 1
6, 1940
3 Claims. (01. 121-41) ,
This invention relates to mechanical relays of
the fluid jet type.
2
According to the present invention, with a
view to avoiding or, minimising pressure pulsa
tions as above mentioned, in relays of the ‘type
‘A relay of the type referred to comprises a
nozzle to which air or other ?uid is continuously
referred to controlled otherwise than by a ma
supplied, usually at constant pressure, and an 5 terial ‘vane, intercepting the stream ?ow, the
transmitting nozzle and receiving ori?ce are ar
ori?ce, which may be the opening to a second
ranged so that in no control position do their
nozzle, which ori?ce receives ?uid from the jet
issuing from the aforesaid nozzle. The nozzle
axes subtend with respect to one another an angle
of less than 5° from coaxial alignment, and that
ing an outlet port andsometimes provided with 10 inat least one control position the axis of the
transmitting nozzle to which the pressure ?uid
means whereby the pressure within the casing
is supplied passes within the area of the receiv
may be controlled, for instance maintained above
ing ori?ce. ,In experimental use of one system
or at or below atmospheric pressure.
'
,
of nozzles it was found desirable for the angle
" The ?uid received in the receiving ori?ce may
act upon a piston or bellows member for effect 15 between the axes to exceed 20°.
Factors affecting the amplitude of the, received
ing some indicating or control operation in ac
pressure pulsations, and hence the angle neces
cordance with the control imposed upon the re
sitated between the axes of the nozzle and re
lay, this control in the present instance being
ceiving ori?ce for the removal wholly or mainly
effected by Varying the degree of ‘impingement
of‘ said pulsations, are the absolute and relative
of the jet upon the’receiving ori?ce. Heretofore
sizes vof the bores of the nozzle and receiving
when this method of control has been employed
ori?ce, the shape of the ori?ces, their distance
the nozzle and receiving ori?ce have been main
apart, the nature of the ?uid medium used, the
tained as far as practicably possible in coaxial
transmitting jet pressure and the pressure of the
alignment when in one control position, the axis
7
ofthevreceiving ori?ce being taken, in this con 25 medium surrounding the jet.
With a relayof the type referred to when the
nection and in the following, as the axis of the
?uid used by the jets is a relatively highly com
receiving nozzle if present (including a receiving
pressible one, such as air, certain irregularities
perforation if the length thereof permits the as
appear to arise which it is believed are dependent
signment of an axis) or the normal to the plane
upon the air velocity being at least in the neigh4
face of the receiving ori?ce if no receiving nozzle
is employed. I
7
bourhood of the velocity of the propagation of
sound. It is known that under these conditions
However, it has been found that-with this-ah
the stream of fluid beyond the transmitting nozzle
rangement, under certain conditions considerable
may enter into a condition of standing waves,
pulsations of the received pressure occur irre
and that the length between nodes'will depend
spectiveof the separation of nozzle and receiving
upon the ratio of pressure of supply to that of
ori?ce over a considerable range, even although
the ?uid’ medium surrounding the jets, whilst
precautions are taken to maintain uniformity of
there is a complicated structure within this jet
the pressure in the transmitting nozzle. These
and certain regions of abrupt change known as
pulsations may also vary in amplitude and be
Riemann lines. It is also know that beyond the
come considerable in parts of the separation
Riemann line the jet conditions may change and
range.
.
cease to be periodic, becoming somewhat inde
In relays as above set forth the method of con
terminate. Considerable experimental investi
trol used may effect the said change in degree
gation has been made on these jets by optical
of impingement in any of various ways such as by
methols along the lines of investigation made by
de?ection of the one axis relatively to the other
Julius Haitmanri-see Ingeniorvidenskabelige
about any suitable centre and whether retain
Slq'ifter 1939, Nr.- 4. These investigations have
ing a coplanar relationship of the axes or not,
tended to con?rm the aforesaid assumptions, and
by movement apart of the two ori?ces along any
have led to the present invention whereby one
line but preferably along the axis of the ?rst
and ori?ce are usually enclosed in a casing hav
or outlet nozzle, or by de?ection of the jet by '
meansof a transverse jet, and the invention is
essentially concerned with relays in which are
employed such methods of control other than by
means of a material vane arranged to ‘intercept’
the stream ?ow.
source of irregularity in the receiving pressure
of the relay can be avoided or minimised.
Therefore, according to a subsidiary feature of
thepresent invention the occurrence of the Rie
mann, line isprevented or substantially prevented
by the use of a convergent-divergent nozzle for
2,408,705
3
4
the transmitter of the relay. In the said experi
mental investigations the shape of the receiving
ing part of the frame 3 and at the other end is
pivoted to a rod ID to which initiating movement
will be imparted when the relay is intended to
operate. Attached to the link 1]‘ of the frame ‘lb
nozzle has not been altered; it has been very
slightly convergent towards the entrance ori?ce.
While the use of a convergent-divergent trans
mitting nozzle has been found very effective it
has been found that there are still certain pulsa
tions in the receiving pressure to be dealt with‘
and according to a further subsidiary feature
of the invention these smaller pulsations or dis l0
is a rod H which rests at its free end on a cam
!2 which is attached to an extension of the pis
ton rod 5b projecting beyond the supporting arm
3b.
With the arrangement described, and assuming
that the normal position of the jet from nozzle
turbances are controlled by the introduction of
1 is such that said jet partially interferes with
a wire or wires or a wire grid across the surface
the under-side of the jet from nozzle l , then, when
the rod Ill is for example depressed, pivot 9a for
of the receiving nozzle. There may be a single
the frame lb‘ will be lowered accordingly to de
wire of diameter about one-tenth that of the ori
?ce placed diametrically across the latter. Alter 15 press nozzle 1 and correspondingly reduce the ex
tent to which the jet from nozzle I is interfered
natively a series of parallel wires may be used.
with by the control ?uid jet from nozzle 1, so
It will be appreciated that the presence of several
that the pressure in the receiving nozzle 2 is
wires unavoidably reduces the available receiv
raised and the pressure in the trapped space 5b
ing pressure.
The invention will now be described with ref 20 of the working cylinder 5 correspondingly in
creased relatively to the constant opposing pres
erence to the accompanying somewhat diagram
sure, in the trapped space 5a, with the result that
matic drawing in which:
Fig. 1 is a perspective view of a ?uid jet rela
the piston 6 will be moved to the left in the draw
ing. With such movement of piston 6,, the at.
in accordance with the invention,
Fig. 2 being an enlarged sectional view of part 25 tached piston rod 6a is moved outwardly from the
working cylinder 5 accordingly to operate mecha
of the transmitting nozzle of the relay, and
Fig. 3 being an enlarged perspective view, part
nism with which the relay will be associated, and
at the same time, the piston rod 81) is moved ac
ly in section, of the receiving nozzle with ?tted
cordingly, thereby retracting the cam I2 and per
mesh diffuser.
'
In Figure 1, l and 2 are nozzles respectively 30 mitting downward movement of the rod H, and
causing the frame 111 to swing about. pivot 9a. in
supported on arms 3a and 32)‘ forming parts of
a ?xed frame mounting 3. The nozzle I has at
the direction to raise the nozzle 1 to its normal
position aforesaid, and so restoring the jet from.
tached to it, at its rear or anchored end, a nip
said nozzle 1 to the position in which it partially
ple 4 to which will be connected a pipe for con
interferes with the under-side of the jet from
veying working fluid, for example air, under
nozzle l. Similarly, for an upward movement of
constant pressure to the interior of the nozzle.
the rod Iii, piston 6 will be moved to the right in
This nozzle constitutes the transmitting nozzle
the drawing accordingly, through piston, rod 60.,
and has a through bore la which, at the outlet
end, is of convergent-divergent form as illus
to operate the mechanism associated with the re—~
trated more clearly in Fig. 2. The nozzle 2, in 40 lay, and, through the rod 6b, to operate the cam
l2 and rod H to rock the frame Tb about pivot
tended to receive the fluid ejected under pres
sure from the transmitting nozzle I and herein
Ea for restoring the nozzle 1, and thus the con
referred to as the receiving nozzle, has a through
trol jet therefrom, to its normal position afore
bore comprising a cylindrical part 2a and a re
said.
duced cylindrical part 21).
Supported in the frame 3 is a cylinder 5 in
which is disposed a piston 6 attached at its front
face to a rod 60. and at the rear face to rod 6b;
If it were desired-that mechanism similar to
that illustrated should respond when a control
?uid jet ejected from nozzle 1 is moved from a
normal position in which said jet interferes with
the rods 6a and Eli extend through substantially
the upper-side of the jet from nozzle I, then the‘
pressure-tight sealing glands mounted in the 50, only change which would be required in the mech
closed opposite ends of the cylinder "5. The bore
anism to ensure restoration of the control jet from
Id. of the transmitting nozzle I registers with a
nozzle 1 to its normal position in relation to the
duct 3a’ in the supporting arm 3a whereby, when
jet from, nozzle 1 would be for the cam 12 to be
pressure ?uid is supplied to the transmitting noz
reversed, namely, so that its inclined surface is
zle- I, pressure fluid is also supplied to the trapped 55 directed upwardly from the left to- right in the
drawing.
>
space 5a of cylinder 5 accordingly‘ to act upon
It is preferable that the transmitting nozzle l
the piston 6. The bore 2a of the receiving noz
and the receiving nozzle 2 are arranged so that
zle registers with a duct 3b’ in the supporting
arm 31) whereby pressure ?uid received by the
the maximum pressure receivable through nozzle
nozzle 2 from the transmitting nozzle 1 is fed 60 2 in the trapped space 522 is approximately half
into the trapped space 5b in cylinder 5 accord
the normal constant pressure in the trapped space
ingly to act upon the piston 6.
5a and that the amount of interference of the
At 1 is shown a third nozzle which, in the ex
control jet from nozzle 1 on the jet from nozzle
ample illustrated, is supported by a bracket ‘la
l is such that the normal received pressure in
attached to a frame lb and is, in turn, supplied
trapped space 5b is about half the maximum
with fluid under constant pressure through pipe
available pressure, that is, about a ‘quarter of the
8, thereby to provide a ?uid jet acting substan
normal constant pressure in the trapped space 5a.
tially at right angles to the fluid jet passing be
Despite this dissimilarity in pressure on. either.
tween the nozzles l and 2, The frame 11) to which
the nozzle 1 is attached comprises‘ a pair of par 70 side of the piston 6, the differential areas are
such that a balance condition is maintained.
allel levers 1c and 7d pivotally connected at their
Advantageously, the design of. the ori?ce in
respective ends to a link ‘Fe extending from the
the control jet nozzle 1 is such that it is not possi
bracket ‘la and to a link ‘if, and is supported on
ble for over-movement of the rod. H). to result
a knife edge 9a intermediately of a beam 9 which,
in such movement of the control jet from nozzle
at one. end, is supported on a knife edge 3c form
2,408,705
5
1 that its in?uence upon the jet from nozzle I
is entirely removed.
_
As shown in Fig. 3, the receiving nozzle 2 is
?tted at its outer end with a cylindrical part 20
having an attached'circumferential ?ange 2d for
supporting a wire grid 26 of relatively ?ne mesh
in a plane substantially at right angles to the
axis of the nozzle, to act as a di?user for said re
ceiving nozzle for the purpose hereinbefore de
scribed.
~
'
nozzle adapted to be supplied with ?uid at con
stant pressure and a receiving nozzle arranged
with the axis of the transmitting nozzle passing
through the area of the receiving nozzle and in
clined to the axis of the receiving nozzle so as to
subtend therewith an angle of at least ?ve degrees
from coaxial alignment, a control nozzle for di
recting ?uid at constant pressure transversely of
the jet from the transmitting nozzle, means re
10 sponsively operable to a control in?uence .for
As represented in Fig. 1, the transmitting and
varying the inclination of incidence of the trans
receiving nozzles I and 2 respectively are mount
ed so that their axes are not in linear alignment
verse jet With the jet from the transmitting noz
but are inclined to one another at an angle or,
with means for supplying ?uid at the pressure
zle, a pressure-responsive servo-piston, together
which angle, for all working positions, has a value 15 in the transmitting nozzle , to one face of said
servo-piston and means for supplying pressure
which exceeds 5° and which willgenerally be in
1 ?uid received in the receiving nozzle to the op
excess of 20°. Moreover, as represented in the
posite face of said servo piston.
drawing, the axis of the transmitting nozzle I
3. A ?uid jet relay comprising a transmitting
will generally pass within the area of the inlet
20 nozzle adapted to be supplied with ?uid at con~
end of the receiving nozzle 2.
stant pressure, a, nozzle for receiving ?uid emitted
I claim:
from the transmitting nozzle, a controlling nozzle
1. A ?uid-jet relay comprising a transmitting
for directing ?uid at constant pressure trans
nozzle adapted to be supplied with pressure ?uid,
versely of the emission from the transmitting
an orifice for receiving the ?uid jet from the
nozzle, means responsively operable to a variable
25
transmitting nozzle, a controlling nozzle for di
control in?uence for correspondingly varying the
recting pressure ?uid transversely of the jet from
angle of incidence between the transverse ?uid
the transmitting nozzle, means responsively 0p
emission and the ?uid emission from the trans
erable to a control in?uence for varying the in
mitting nozzle, means continuously responsive to
clination of incidence of the transverse jet with 30 the difference between the pressure in the trans
the jet from the transmitting nozzle, means re
mitting nozzle and the pressure in the receiving
sponsive to pressure ?uid received by the receiv
nozzle for rendering available an in?uence which
ing ori?ce for rendering available an in?uence
is at all times substantially representative in
representative of said control influence, said
magnitude of said control in?uence, said trans
transmitting nozzle and receiving nozzle being
mitting nozzle and receiving nozzle being ar
arranged with the axis of the transmitting noz
ranged so that the axis of the transmitting noz~
zle passing through the area of the receiving noz
zle‘passes through the area of the receiving nozzle
zle and inclined to the axis of the receiving ori?ce
and is inclined to the axis of the receiving nozzle
so as to subtend therewith an angle of at least
so as to subtend therewith an angle of at least
?ve degrees from coaxial alignment.
?ve degrees from coaxial alignment.
2. A ?uid-jet relay comprisinga transmitting
KEITH WATSON TODD.
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