Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to a kit of parts for a
differential-pressure control valve. The differential-pressure
control valve is intended in particular for use in heating systems
having radiators, in which the pressure difference between the inlet
line and the return line is to be kept constant for the purpose of
uniform supply.
The kit of parts is intended to allow two arrangements of
such a differential-pressure valve to be produced using largely the
same components. In particular, it is intended that the installer
shall be able to select one or other arrangement on site.
Generally speaking, the present invention provides a kit of
parts for a differential-pressure control valve, comprising: a valve
housing with a valve stem passing, sealed, to the outside and first
fixing elements arranged in the region of the outlet point; a first
diaphragm capsule, which in a first arrangement is arranged to be
mounted on the valve housing and for that purpose has second fixing
elements matching the first fixing elements for connection of the
capsule to the valve housing, and a diaphragm of the first diaphragm
capsule carrying an abutment surface, which in the first arrangement
is connected non-positively directly to the valve stem; a top unit,
which is connected or is arranged to be connected to the first
diaphragm capsule, and has adjustable set-point springs which act in
the opening direction of the valve; and a second diaphragm capsule,
which in a second arrangement is arranged to be mounted on the valve
housing and for that purpose has third fixing elements matching the
first fixing elements and which on the opposite side, for the purpose
of mounting the first diaphragm capsule in the second arrangement, has
fourth fixing elements corresponding to the first fixing elements and
has a diaphragm which is displaceably held on a diaphragm stem and by
way of a stop member acts together with the stem by means of a non-
positive connection to couple the valve stem with the diaphragm of the
first diaphragm capsule, whereby the diaphragm stem in the second
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arrangement is inserted between the abutment of the diaphragm of the
second diaphragm capsule and the valve shaft in a non-positive manner.
Using a valve housing, a first diaphragm capsule and a top
unit, a differential-pressure control valve is produced that responds
exclusively to the pressure difference on both sides of the diaphragm
of the first diaphragm capsule, and in particular therefore to the
difference between the inlet pressure and the return pressure. A
differential-pressure control valve of that kind has already been
described in copending, commonly owned Canadian Patent Application
No. 2,077,280.
The second arrangement is produced from the above-mentioned
components and the second diaphragm capsule which, by virtue of the
matching fixing elements and the associated diaphragm stem, can be
installed very easily between the valve housing and the first
diaphragm capsule. With the second diaphragm capsule, the pressure
drop at a restrictor can be monitored, as is known (Samson AG "Me~ und
Regeltechnik", type sheet T 3017, page 148). This enables the flow
rate to be limited in addition to controlling the pressure difference.
In spite of all that, the diaphragm capsules need not be
dismantled, but can be used in their entirety as constructional units.
There is also no risk of the diaphragms being damaged during the
conversion.
The use of external threads and union nuts results in a very
simple and stable connection of the individual components.
A non-positive connection enables the individual components
to be connected together easily without special joining means having
to be provided between the valve stem, abutment surface and diaphragm
stem.
A non-positive connection also allows a free movement of the
diaphragm of the second diaphragm capsule during the operation of
controlling the pressure difference, and allows this diaphragm to
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exert an influence in the event of a limit value of the flow rate
being exceeded.
The guide means keeps the diaphragm stem on its axial
movement path, so that despite the non-positive connection it serves
as a reliable force-transmitting member.
The construction of the invention enables the adjacent
pressure spaces of the first and second diaphragm capsules to be
interconnected, so that only one control line connection is required
for that purpose.
With the construction of this invention it is also possible
to supply the pressure space of the second diaphragm capsule facing
towards the valve housing with pressure from a valve chamber, which
likewise saves a control line connection.
The loading spring is expedient in many cases for imparting
to the diaphragm of the second diaphragm capsule the bias that it
requires for its function. A loading spring of this kind can easily
be fitted during assembly. All that is required is to support it on
the valve housing prior to putting the second diaphragm capsule in
posltion .
It is possible to use two half-shells which are joined to
one another by crimping, because the diaphragm capsules can be handled
complete. The diaphragm is also well protected.
The crimp connections also contribute to the provision of
the diaphragm capsules as non-separable components which can be
installed without great concentration.
By using an adjustable throttling element in the valve the
restrictor is formed, the pressure drop of which serves to actuate the
second diaphragm capsule.
The invention is explained in detail hereinafter with
reference to a preferred embodiment illustrated in the drawing, in
which
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Fig. 1 shows a longitudinal section through a first
arrangement of a differential-pressure control valve made from the kit
of parts according to the invention,
Fig. 2 shows a longitudinal section through a second
arrangement of a differential-pressure control valve made from the kit
of parts according to the invention,
Fig. 3 shows an enlarged longitudinal section through the
first and the second diaphragm capsule and
Fig. 4 shows a diagrammatic circuit diagram for the
installation of the second
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arrangement of the differential-pressure control
valve.
The kit of parts according to the invention comprises
essentially four components, namely, a top unit 1, a first
diaphragm capsule 2, a second diaphragm capsule 3 and a valve
housing 4. For the second arrangement (Fig. 2), all four
components are used, for the first arrangement (Fig. 1) the second
diaphragm capsule 3 is omitted; the first diaphragm capsule 2 is
positioned directly on the valve housing 4. The first arrangement
corresponds to the differential-pressure control valve according
to Canadian Application 2,077,280; refer to this application for
further details.
The top unit 1 has a rotary knob 5 with which a
supporting plate 6 for a setpoint spring 7 can be adjusted. This
setpoint spring 7 acts by way of an intermediate member 8 with
upwardly directed force on a connecting shaft 9 belonging to the
first diaphragm capsule 2. Moreover, the top unit 1 has a base 10
with which it can be secured to the first diaphragm capsule 2.
The valve housing 4 has an inlet nipple 11, an outlet
nipple 12 and between them a valve seat 13. In a neck portion 14
there is inserted an insert 15 which forms a guide means for a
valve stem 16 which also carries a closure member 17. A restrictor
18 is formed by means of a throttling element 19 which is in the
form of a cup with an inwardly curved rim, and is vertically
adjustable from the outside by means of a screw 20 to change the
restrictor cross-section. The valve chamber 21 between the
restrictor 18 and the valve seat 13 is in connection, by way of a
connecting channel 22, which runs through the closure member 17 and
the valve stem 16, and by way of an outlet 23 passing through the
insert 15, with the top side of this insert 15. A sheet-metal cup
24 separates this connecting channel from the outlet-side valve
chamber. The valve stem 16 carries at its upper end a plate 26
against which a valve spring 27 that loads the closure member 17
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in the opening direction bears. On the outside of the neck portion
14 there is provided a first fixing element 28 in the form of an
external thread.
The diaphragm capsule 2 comprises two half-shells 30 and
31 which are joined together at their edge by a crimp 32 which also
holds the edge of a diaphragm 33 firmly clamped. The upper
half-shell 30 carries a connecting nipple 34 for a control line and
a crimp-mounted insert 35, through which the operating shaft 9
passes, sealed, to the outside. The top unit 2 is connected to the
diaphragm capsule 2 by interengagement of the base 10 with the
insert 35. At the opposite end, a connecting ring 36 is crimped
on, and by means of a step 37 holds captive a second fixing element
38 in the form of a union nut. The diaphragm 33 is reinforced by
a double plate 39, in the centre of which an insert 40 is mounted
by crimping. Connected to the insert by way of a joint 41 is the
shaft 9. The insert contains a non-return valve 42 which enables
the pressure space 43 below the diaphragm 33 to be connected to the
pressure space 44 above this diaphragm when the pressure difference
is too great. On the underside of the insert 40 there is provided
an abutment surface 45. The diaphragm 33 is loaded by a first
spring 46, which is housed in the pressure space 43, and in the
opposite direction is loaded by a spring 47, which is housed in the
pressure space 44. The spring 46 projects through an open region
48 of the lower half-shell 31 and bears against the second
diaphragm capsule 3. The spring 47 bears against the insert 35.
The second diaphragm capsule 3 also comprises two
half-shells 50 and 51, which are joined together at their edge by
crimping 52 which also grips the edge of the diaphragm 53. The
upper half-shell carries a connecting nipple 54 for a control line.
An insert 55 is crimp-mounted on the shell and carries on its
outside a fourth fixing element 56 in the form of an external
thread identical to first fixing element 28. The insert 55 forms
a guide means 57 for a diaphragm stem 58 and has a through-channel
59. The lower half-shell 51 is provided with a crimped-on
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connecting ring 60 which by means of a step 61 carries a third
fixing element 62 in the form of a union nut identical to second
fixing element 38. An open region 63 remains inside this
connecting ring. The diaphragm 53 is reinforced by a double plate
64. On one side the double plate engages a stop member 65 of the
diaphragm stem 58 but is otherwise displaceable on this diaphragm
stem. The diaphragm 53 divides the diaphragm capsule 3 into two
pressure spaces 66 and 67 and is loaded by a loading spring 68
which passes through the open region 63 and bears on the valve
housing 4.
The fixing elements are designed so that both the second
fixing element 38 of the diaphragm capsule 2 and the third fixing
element 62 of the diaphragm capsule 3 are capable of acting
together with the first fixing element 28 on the valve housing 4.
The diaphragm capsule 3 additionally has the fourth fixing element
56 which is capable of acting together with the second fixing
element 38 of the first diaphragm capsule 2. The two arrangements
shown in Figs. 1 and 2 can be produced in this manner.
Assuming that the pressure-difference control valve is
arranged in the return line of a heating system, in the first
arrangement shown in Fig. 1 the diaphragm capsule 2 is mounted by
means of the fixing elements 28 and 38 on the valve housing 4 and
the connection 34 is connected to the inlet line. This means that
the pressure space 44 carries inlet pressure and the pressure space
43, because it is connected to the valve chamber 21 by way of the
connecting channel 22, carries return pressure. Consequently, the
diaphragm capsule 2 produces a force acting in the closing
direction of the valve, which essentially counteracts the force of
the set-point spring so that a state of equilibrium develops.
Under the influence of the valve spring 27, the plate 26 of the
valve stem 16 lies non-positively on the bearing surface 45 of the
insert 40.
In the second arrangement shown in Fig. 2, the diaphragm
capsule 3 is additionally inserted between the diaphragm capsule
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2 and the valve housing 4. Through the fixing elements 28 and 62
acting together it is joined to the valve housing 4, and through
the fixing elements 56 and 38 acting together it is joined to the
diaphragm capsule 2. The length of the diaphragm stem 58
corresponds approximately to the height of the diaphragm capsule
3 and is dimensioned so that under the influence of the valve
spring 27 the plate 26 of the valve stem 16 merely engages the stop
member 65 of the diaphragm stem 58 without positive contact and its
end face merely engages the abutment surface 45 of the insert 40
without positive contact. It is, however, possible for the
differential pressure in the diaphragm capsule 3 to take over the
valve control, if the differential pressure effective there exceeds
the force of the spring 68. The diaphragm stem 58 is then lifted
from
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the bearing surface 45 and controls the closure member
17 further into the closed position.
A preferred example of the application of the
second arrangement is illustrated in Fig. 4. A
heating system has several radiators 70, 71 and 72,
each of which is supplied with hot water by way of a
thermostatic valve 73, 74 and 75 from a main inlet line
76 by way of a branch inlet line 77. The hot water
returns by way of a branch return line 78 and a main
return line 79 to the central heat source. A
differential-pressure control valve according to Fig. 2
is fitted into the branch return line 78. The
connection 34 is connected to the branch inlet line 77
and the connection 54 iS connected to the branch return
line 78. The connecting line 22 joins the lower
pressure space 66 of the diaphragm capsule 3 to the
valve chamber 21. The through-channel 59 joins the
upper pressure space 67 of the diaphragm capsule 3 to
the lower pressure space 43 of the diaphragm capsule 2.
The diaphragm capsule 2 therefore controls the valve
operation so that the pressure drop between the branch
inlet line 77 and the branch return line 78 remains
approximately constant. The diaphragm capsule 3
ensures that the valve throttles whenever the pressure
drop across the restrictor 18 is too great, that is,
too great a flow rate is detected. Because the
restrictor 18 arranged inside the valve housing 4 is
adjustable, the maximum desired flow rate can be set
using a spring 68 rated for all cases.
