Flow control valve with integrated pressure controller

A flow control valve has two successively arranged throttle locations. The first throttle location serves as an adjusting member for the through-flow. The second throttle location controls the pressure difference across the first throttle location to a constant value. The first throttle location is formed by a control member (4) which co-operates with a first valve seat (5) of a valve insert (7) which is fixedly connected to the valve housing (6). The second throttle location is formed by a pressure regulating member (9) which co-operates with a second valve seat (10) of the valve insert (7). The control member (4) and the pressure regulating member (9) are displaceable in an identical direction (12) and connected by means of a resilient diaphragm (13). The inlet chamber (1) is communicated with a pressure chamber (15) which acts on the diaphragm (13) and on the pressure regulating member (9). The operative surface which transmits the pressure (p.sub.1) obtaining in the inlet chamber (1) to the pressure regulating member (9) is approximately equal to the operative surface which transmits the pressure (p.sub.2) obtaining between the two throttle locations to the pressure regulating member (9). In that arrangement the flow medium flows rotationally symmetrically through the second throttle location.

The invention concerns a flow control valve with integrated pressure 
controller of the kind set forth in the classifying portion of claim 1. 
In accordance with the teaching of European patent EP 677 708 such flow 
control valves are suitable for example for use as heating body valves in 
a hot water heating system in which a plurality of heating bodies are 
hydraulically connected together in at least one line. With such flow 
control valves, the individual heating bodies can be operated with a level 
of heating output which remains the same, independently of the 
respectively prevailing pressure drop which is influenced by the operation 
of the other heating bodies. That is achieved in known manner by a control 
member which controls the through-flow of a flow medium and a pressure 
regulating member which regulates the pressure drop at the control member. 
A flow control valve of the kind set forth in the classifying portion of 
claim 1 is known from U.S. Pat. No. 3,344,805. The flow control valve 
which is designed for industrial installations suffers from the 
disadvantage that the pressures which act on the pressure regulating 
member are asymmetrical as the flow medium which flows through the valve 
is discharged in an irregular fashion, that is to say at one side, and in 
addition, with an increasing degree of opening of the pressure regulating 
member, the pressure drop at the control member can no longer be 
satisfactorily regulated by varying, that is to say changing, surface 
areas by way of which the corresponding prevailing pressures apply forces 
to the control member and the pressure regulating member. In addition the 
seal in the form of an O-ring which is disposed between the drive bar of 
the control member and the pressure regulating member involves relatively 
high frictional forces whereby this valve is not suitable as a 
thermostatic valve. 
A further flow control valve is known from European patent application EP 
751 448. That relatively large valve is also not suitable for use as a 
heating body valve. 
French patent application FR 2 740 544 discloses a valve having a single 
throttle location wherein the quantitative through-flow rate is 
approximately independent of the pressure drop. This unit however does not 
have an adjusting means for adjusting the rated through-flow, that is to 
say a control member. 
The invention is based on the problem of improving a flow control valve of 
the specified kind in such a way that the dimensions are more compact, 
that the pressure regulating member of the control valve is movable as 
easily as possible in order to reduce the level of pressure hysteresis, 
and that the valve is suitable for use as a heating body valve. 
The invention solves that problem by virtue of the features of claim 1. 
Further advantageous configurations are set forth in the appendant claims. 
The invention discloses a flow control valve for controlling the 
through-flow of a flow medium, comprising an inlet chamber, two 
successively arranged throttle locations and an outlet chamber, wherein 
the first throttle location serves as an adjusting member for the 
through-flow and wherein the pressure difference across the first throttle 
location is controlled to a constant value by means of the second throttle 
location. In that arrangement the first throttle location is formed in 
known manner by a control member which co-operates with a first valve seat 
for controlling the through-flow while the second throttle location is 
formed by a pressure regulating member which co-operates with a second 
valve seat for controlling the pressure difference. 
The inlet chamber is communicated with a pressure chamber which at least 
partially acts on the pressure regulating member insofar as the flow 
medium can circulate freely between the inlet chamber and the pressure 
chamber, that is to say in particular the same pressure obtains in the 
pressure chamber as in the inlet chamber. In that respect, a first 
operative surface which transmits the pressure obtaining in the inlet 
chamber to the pressure regulating member is approximately equal to a 
second operative surface which transmits the pressure obtaining between 
the two throttle locations to the pressure regulating member, and the 
pressure regulating member, by virtue of a rotationally symmetrical 
structure and by virtue of the rotationally symmetrical configuration of 
the outlet chamber downstream of the second throttle location, permits a 
rotationally symmetrical through-flow of the flow medium. 
The pressure regulating member and the valve housing are connected by means 
of a resilient diaphragm, wherein the diaphragm is also connected to the 
control member when the pressure regulating member is arranged on the 
drive side of the control member. Then in that way the control member and 
the pressure regulating member are connected by means of the resilient 
diaphragm which is displaceable in an identical first direction. The 
resilient diaphragm serves for movably mounting the pressure regulating 
member and for sealing off the pressure chamber. The pressure regulating 
member can move freely by means of being suspended by the diaphragm, 
between the valve housing and the control member which is displaceable by 
the drive but otherwise fixed. In that respect the diaphragm is fixed to 
the control member or the drive bar or spindle for driving the control 
member, in such a way that it seals off the pressure chamber with respect 
to the space or chamber between the throttle locations. That eliminates 
any O-ring seals and the arrangement guarantees that the control member is 
displaced with a very easy motion and that the pressure regulating member 
is also moved almost without friction relative to the control member. 
Furthermore the diaphragm guarantees reliable sealing integrity which is 
independent of the movements of the individual members, to prevent a 
pressure drop in the individual chambers of the valve. When the pressure 
regulating member is arranged on the side remote from the drive for the 
control member, the pressure regulating member is directly connected to 
the valve housing by means of the diaphragm. 
The pressure regulating member and the control member are advantageously of 
a conical or at least partially conical shape in order to ensure a 
configuration which is as advantageous as possible in terms of flow 
dynamics for the flow medium. 
The pressure regulating member, the control member and the corresponding 
connections, also by way of the diaphragm, are of such a nature, and in 
particular the corresponding valve seats in relation to the members, that 
a third operative surface which transmits the pressure obtaining in the 
inlet chamber to the control member in the first direction is 
approximately equal to a fourth operative surface which transmits the 
pressure obtaining in the inlet chamber to the control member in the 
direction opposite to the first direction. In that situation, the third 
operative surface is disposed on the side of the control member, which is 
towards the inlet chamber, and the fourth operative surface is disposed on 
the side of the control member, which is towards the pressure chamber. The 
sum of the first operative surface and the fourth operative surface is 
approximately the same as the sum of the second operative surface and the 
third operative surface, wherein the operative surfaces arise out of such 
"engagement surfaces" which permit exertion or transmission of force, 
caused by the corresponding pressures, in the first direction, identified 
in the Figures as the y-direction. 
The pressure regulating member is of such a configuration that the force 
which, due to the pressure obtaining in the outlet chamber, at least 
partially acts on the pressure regulating member in the first direction, 
corresponds to the force or forces which, due to the pressure obtaining in 
the outlet chamber, at least partially act on the pressure regulating 
member in a direction opposite to the first direction (12). 
The forces caused by the pressure obtaining in the outlet chamber, and the 
forces caused by the pressure obtaining in the inlet chamber and in the 
pressure chamber and the pressure obtaining between the throttle locations 
and/or the forces caused by the flow of the flow medium at least through 
the second throttle location, respectively, act symmetrically on the 
corresponding movable members within the valve, due to the shaping and the 
above-mentioned configuration of the pressure regulating member, the 
diaphragm, the control member and the pivotal connections or guide means 
and the throttle locations. By virtue of the forces acting in a 
symmetrical relationship the valve can be designed with the approximately 
equal-sized operative surfaces, as a small unit, for use as heating body 
valves. 
In the region around the second throttle location, by means of vanes or 
ribs which are arranged approximately in parallel relationship with the 
first direction and which serve to provide for low-friction guidance of 
the pressure regulating member, the pressure regulating member forms at 
the same time flow chambers which prevent a flow of the flow medium in 
directions which are not approximately parallel to the first direction. In 
addition there are means for increasing the mass of the pressure 
regulating member which, together with the flow chambers, prevent flutter 
or resonance oscillations of the pressure regulating member, by virtue of 
its free mobility and the medium flowing through the arrangement. 
The second throttle location is formed by a conical surface which 
co-operates with a sharp-edged counterpart portion, so that, as a result 
of the very small surface areas, the forces produced by the flow in 
accordance with Bernoulli's law on the pressure regulating member (9) 
remain as low as possible. Furthermore the control member advantageously 
has a rubber portion which forms the first throttle location with the 
first valve seat, the rubber portion having a sealing lip which 
sectorially delimits the through-flow of the flow medium through the first 
throttle location. 
Advantageously, the control member has a chamber whose volume is at least 
half as great as the variation in volume produced in the pressure chamber 
by a full stroke change, in order to facilitate any stroke movements that 
may occur due to the exchange of the flow medium, without deposits passing 
out of the circuit into the pressure chamber. 
Advantageously, the valve housing together with all parts related to the 
functioning of the flow control valve is releasably connected to the pipe 
or housing forming the inlet chamber and the outlet chamber, so that the 
valve can be fitted for example only after installation of the heating 
pipes.

FIG. 1 shows the principle of the invention and serves for easier 
explanation of the valve shown in FIG. 2. The reference numerals used 
correspond to each other. FIG. 1 showing additional lines or conduits 41, 
42 and 43 which pass the corresponding pressures in the individual 
chambers to the "pressure control vessel" or the diaphragm drive 36 shown 
in the lower part of FIG. 1. Also to be noted are the forces shown at the 
right-hand edge in FIG. 1, in the first direction 12. In that respect a 
motor 35 drives the control cone 4. 
FIG. 2 shows a flow control valve operating on the basis of the principle 
illustrated in FIG. 1, through the inlet chamber 1 of which the flow 
medium which flows in the x-direction 2 passes into the flow control valve 
and through the outlet chamber 3 of which the flow medium again leaves the 
flow control valve in the same x-direction 2, as is also illustrated by 
arrows. Two series-connected throttle locations are disposed between the 
inlet chamber 1 and the outlet chamber 3. The first throttle location is 
formed by a control member 4 co-operating with a first valve seat 5, 
wherein the valve seat 5 can be for example a valve insert 7 which is 
fixedly connected to the valve housing 6, to form a first adjustable 
opening 8. The control member 4 has a sealing element 4a so that the 
opening 8 is sealingly closed in the closed condition of the flow control 
valve. The second throttle location is formed by a pressure regulating 
member 9 co-operating with a second valve seat 10, for example of the 
valve insert 7, for forming a second adjustable opening 11. The pressure 
in the inlet chamber is denoted by p.sub.1 the pressure between the two 
throttle locations is denoted by p.sub.2 and the pressure in the outlet 
chamber is denoted by p.sub.3. Those pressures are passed through the 
lines or conduits 41, 42, 43 shown in FIG. 1 to the diaphragm drive 36 
which is described in greater detail hereinafter. 
The first throttle location serves as an adjusting member for the 
through-flow, while the function of the second throttle location is that 
of keeping constant the pressure difference p.sub.1 -p.sub.2 across the 
first throttle location, so that the through-flow is independent of the 
pressure difference p.sub.1 -p.sub.3 which obtains across the flow control 
valve. The flow medium flows through the flow control valve in the 
x-direction 2. The control member 4 and the pressure regulating member 9 
are displaceable along a y-direction 12 which is directed perpendicularly 
to the x-direction 2. The y-position of the control member 4 determines 
the degree of opening of the first opening 8 and thus the through-flow. 
The control member 4 is actuated by a reference value setting device, for 
example a remotely controlled electric-motor drive 35 or a thermostatic 
drive. 
The pressure regulating member 9 is connected by way of a resilient 
diaphragm 13 both to the control member 4 and also to the valve housing 6. 
The diaphragm 13 is part of a hydraulic drive which controls the position 
of the pressure regulating member 9 with respect to the second valve seat 
10, and thus the degree of opening of the second opening 11, That control 
action is allowed by virtue of the fact that on the one hand the input 
pressure p.sub.1 and on the other hand the pressure p.sub.2 acting between 
the throttle locations act on the diaphragm 13. In order to produce that 
effect, the inlet chamber 1 is connected by way of a bore 14 in the 
control member 4 to a pressure chamber 15 which acts on the diaphragm 13 
and on the pressure regulating member 9. The pressure p.sub.1 thus exerts 
on the pressure regulating member 9 a force F.sub.1 acting in the negative 
y-direction 12. On the other hand the pressure p.sub.2 exerts on the 
pressure regulating member 9 a force F.sub.2 acting in the positive 
y-direction 12. The operative surface at which the pressure p.sub.1 acts 
on the diaphragm 13 or on the pressure regulating member 9 is of the same 
size as the effective surface at which the pressure p.sub.2 acts on the 
diaphragm 13 or on the pressure regulating member 9. The resultant force 
F.sub.1-F.sub.2 is therefore directly proportional to the differential 
pressure p.sub.1 -p.sub.2. A control spring 16 which is stressed between 
the valve insert 7 and the pressure regulating member 9 exerts a force 
F.sub.R acting in the positive y-direction 12 on the pressure regulating 
member 9. The degree of opening of the opening 11 is so set that the 
forces F.sub.1 -F.sub.2 and F.sub.R are of the same magnitude. 
The control spring 16 could also be operatively disposed between the 
pressure regulating member 9 and the control member 4, although that would 
involve tolerating a slight impairment in terms of the valve 
characteristics. 
The operative surface A.sub.1 at which the pressure p.sub.1 acts on the 
diaphragm 13 or on the pressure regulating member 9 extends in a radial 
direction substantially between the two apex points S.sub.1 and S.sub.2 of 
the diaphragm 13 in rotationally symmetrical relationship centred around 
the centre line B of the valve member in the y-direction 12. The operative 
surface A.sub.2 at which the pressure p.sub.2 acts on the diaphragm 13 or 
on the pressure regulating member 9 extends in the radial direction 
substantially from the apex point S.sub.1 of the diaphragm 13 to the 
second valve seat 10. The valve seat 10 and the apex point S.sub.2 are 
therefore approximately on a line which is parallel to the y-direction 12. 
It is to be noted here that the spacing of the apex points S.sub.1 and 
S.sub.2 relative to the y-line 12 is slightly dependent on the position of 
the control member 4 and the position of the pressure regulating member 9. 
In addition the control member 4 is of such a configuration that the 
operative surface A.sub.4 which is exposed in the upper region of the 
control member 4 to the pressure p.sub.1 of the pressure chamber 15 and 
which extends substantially radially between the centre line B and the 
apex point S.sub.1 approximately corresponds to the operative surface 
A.sub.3 which results from the diameter of the first throttle location or 
the spacing of the centre line B relative to the first valve seat 5. That 
therefore ensures a force equilibrium which extends both over the control 
member 4 so that the force necessary to move the control member is minimal 
and also over the pressure regulating member 9 so as to afford the desired 
pressure stability for the through-flow of the first throttle location 
independently of the pressure p.sub.3 of the outlet chamber. 
The rotationally symmetrical structure of the entire flow control valve 
means that the water flows through the second throttle location over the 
entire angular range of 360.degree. so that consequently the stroke 
movement of the pressure regulating member 9, that is required for the 
control action, is minimal. A change in the position of the pressure 
regulating member 9 as a result of a change in the outer pressure 
difference p.sub.1 -p.sub.3 thus results in the smallest possible change 
in stroke and thus the smallest possible change in the force F.sub.R 
applied to the pressure regulating member 9 by the control spring 16 and 
thus the smallest possible change in the operative pressure p.sub.1 
-p.sub.2 determining the through-flow. 
The resilient diaphragm 13 permits practically friction-free movement both 
of the control member 4 and also of the pressure regulating member 9 along 
the y-direction 12. Guidance for the pressure regulating member 9 in the 
y-direction is ensured by vanes or ribs 17 co-operating with the valve 
insert 7 or the valve member 6 itself. The pressure regulating member 9 
preferably has a cylindrical casing portion 18 which is formed parallel to 
the y-direction 12 and which connects the vanes 17 so that small flow 
chambers are formed between the vanes 17. Now, any movement of the 
pressure regulating member 9 in the x-direction 2 means that some of the 
flow chambers become smaller and others become larger. The redistribution 
of the flow medium, which is required in that situation, is however made 
more difficult as the flow chambers make it very much more difficult for 
the flow medium to flow in the x-direction 2. Oscillations of the pressure 
regulating member 9 are in that way heavily damped if not entirely 
prevented. 
The mass of the pressure regulating member 9 can be increased by means of a 
ring 19 which is fitted onto the pressure regulating member 9, for example 
consisting of brass, copper or sealed lead, and in that way the resonance 
frequency of the possible oscillations can be lowered. As a result the 
resonance frequency is lower than the excitation frequencies caused by the 
flow. 
The pressure p.sub.3 also acts on the diaphragm 13 and exerts a force 
F.sub.3 acting in the positive y-direction 12 on the pressure regulating 
member 9. To compensate for that force F.sub.3 the pressure regulating 
member 9 has an extension portion 20 which is acted upon by the pressure 
p.sub.3 in such a way that a force F.sub.4 directed in the negative 
y-direction 12 also acts on the pressure regulating member 9. It is to be 
noted here that the pressure p.sub.3 also acts on the extension portion 20 
in the region of the second valve seat 10 and exerts a force F.sub.5 which 
also acts in the positive y-direction 12 on the pressure regulating member 
9. The operative surface area of that extension portion 20 is equal in 
size to the operative surface at which the pressure p.sub.3 acts on the 
diaphragm 13 so that the forces F.sub.3, F.sub.4 and F.sub.5 compensate 
for each other. The pressure p.sub.3 in the outlet chamber 3 then has no 
influence on the position of the pressure regulating member 9. 
In the region of the second valve seat 10 the pressure regulating member 9 
has a conical surface 21 which in the cross-sectional view appears as an 
inclined edge. The second valve seat 10 is of a sharp-edged configuration, 
wherein the edge 22 touches the conical surface 21 of the pressure 
regulating member 9 along a circular line when the second throttle 
location is closed. The cross-sectional area which is operative for the 
through-flow is at the lowest in the immediate region of the opening 11 
and therefore the flow rate of the flow medium is at its highest there. 
Therefore, the pressure is reduced there, in accordance with Bernoulli's 
law. The result of this is that in the immediate proximity of the opening 
11 it is not the pressure p.sub.2 or p.sub.3 that acts on the pressure 
regulating member 9, but a pressure which is reduced with respect to the 
pressure p.sub.2 or p.sub.3 respectively. That results in a reduction in 
the force F.sub.2 which acts overall on the pressure regulating member 9. 
The reduction in the force F.sub.2 can be partially compensated by way of 
a corresponding increase in the area of the surface at which the pressure 
p.sub.2 acts on the pressure regulating member 9. 
As now however the reduction in the force F.sub.2 within the working range 
of the flow control valve is not constant but depends on the degree of 
opening of the opening 11, there still remains a slight dependency in 
respect of the through-flow, on the pressure difference p.sub.1 -p.sub.3 
obtaining across the flow control valve. If however the valve seat 10 were 
not of a sharp-edged configuration as described, but were provided with a 
surface which is disposed parallel to the conical surface 21, then the 
range where it is no longer the pressure p.sub.2 but a lower pressure that 
acts on the pressure regulating member 9 would be even larger. That means 
that the dependency of the through-flow on the pressure difference p.sub.1 
-p.sub.3 obtaining across the flow control valve would also be more 
pronounced. 
The reduction, caused as a result of the flow, in the pressure p.sub.3 
acting on the extension portion 20 is expressed in a reduction in the 
magnitude of the force F.sub.5. The reduction in the force F.sub.5 is 
dependent on the flow speed and thus the through-flow. In order to 
minimise that effect the extension portion 20 extends in the radial 
direction as little as possible beyond the valve seat 10 defined by the 
inner edge, that is to say only as far as is necessary as a result of 
inevitable tolerances. 
Provided within the control member 4 is a chamber 23 whose volume in the 
ideal situation is at least as large and advantageously at least half as 
large as the variation in volume of the pressure chamber 15, which is 
caused by a full stroke variation. In the event of a stroke movement of 
the control member 4 or the pressure regulating member 9, the volume of 
the pressure chamber 15 varies, as a result of which there would have to 
be an exchange of flow medium between the pressure chamber 15 and the 
inlet chamber 5. The chamber 23 can entirely or at least partially 
accommodate that more or less amount of flow medium so that exchange 
between the pressure chamber 15 and the inlet chamber 1 occurs only in the 
event of large stroke variations in respect of the control member 4. The 
risk of contamination of the pressure chamber 15 or the bore between the 
chamber 23 and the pressure chamber 15 is thus reduced. 
FIG. 3 shows the second throttle location on a larger scale than FIG. 1 or 
FIG. 2, so that the details in regard to configuration are more clearly 
visible here, FIG. 3 now further shows an embodiment of the first throttle 
location in which a rubber portion 24 is fitted onto the control member 4 
and co-operates with the first valve seat 5. The rubber portion 24 has a 
sealing lip 25 which bears laterally against the first valve seat 5 and 
thus ensures sealing integrity. As is shown in FIG. 4, the sealing lip 25 
embraces any angle .phi. which can be for example 120.degree. or 
270.degree. and therefore limits the flow through the first throttle 
location sectorially. The opening cross-section of the first throttle 
location depends on the stroke of the control member 4 and the periphery 
of the gap opening which is formed in that case. The periphery of the gap 
opening and thus the quantitative through-flow are reduced as a function 
of the stroke, with the sealing lip 25. An advantage with this 
construction is that the range in which the quantitative through-flow is 
controllable is enlarged downwardly and that the risk of blockage due to 
dust and dirt particles is reduced. The sealing lip 25 is narrow and at 
its two ends has an undercut configuration. In the event of possible 
swelling of the rubber portion 24, that is intended to ensure that the 
throttle location remains fully operational: the force which acts upon a 
variation in the stroke of the control member 4 is either sufficient for 
the sealing lip 25 also to perform the variation in stroke without any 
problem or for just the control member 4 to implement the variation in 
stroke, in which case it will be appreciated that the sealing lip 25 
clinging to the valve seat 5 is then deformed. Provided above the sealing 
lip 25 is a relatively large cavity 26 (FIG. 3) so that any deposits of 
dirt or lime cannot cause the rubber portion 24 to become stuck. 
To minimise the friction between the sealing lip 25 and the first valve 
seat 5, a further cavity 33 is preferably also provided behind the sealing 
lip 25, the cavity 33 permitting the sealing lip 25 to yield in a radial 
direction. 
The rubber portion 24 comprises water-resistant rubber. Therefore, in the 
event of oil contamination of the medium flowing through the flow control 
valve, it can happen that the rubber portion 24 swells up. The described 
structure ensures that the flow control valve nonetheless operates 
reliably. 
The control member 4 is connected to a spindle 27 which is actuable 
manually or by a drive (not shown) for adjusting the opening 8. The 
spindle 27 is passed through a bore 28 in a mounting portion 29 which 
serves to guide and support the spindle 27. An O-ring 30 serves to seal 
off the pressure chamber 15 relative to the exterior. FIG. 5 shows the 
bore 28 in cross-section. The bore 28 is not round but has recesses 31 
which are directed radially outwardly from the round shape so that between 
the spindle 27 and the mounting portion 29 there remain a plurality of 
gaps through which the medium, generally heating water, can freely 
circulate at any time between two sides of the mounting portion 29. That 
prevents solid constituents from crystallising out in the bore 28 and thus 
prevents the spindle 27 from jamming. The bore 28 is nonetheless of such a 
configuration that satisfactory guidance of the spindle 27 is guaranteed, 
as in the case of a round bore. So that the control member 4 (FIG. 1) can 
follow a movement of the spindle 27 in the positive y-direction 12 without 
delay, operatively disposed in known manner between the control member 4 
and the valve housing 6 is a second spring which exerts on the control 
member 4 a force which acts in the positive y-direction 12. 
FIG. 6 shows an embodiment of the flow control valve which is suitable for 
simple installation in a radiator piping arrangement 32. In the case of 
this valve the feed and discharge of the heating water occur coaxially 
along the direction 12 in which the control member 4 and the pressure 
regulating member 9 are displaceable. The Figure shows this modification 
in two different variations. Mounted on the control member 4 is a sealing 
element 4a which serves for reliably sealing off the control valve and 
which can optionally be provided with the sealing lip 25 for sectorial 
through-flow regulation of the flow medium. The upper region of the 
spindle 27 is passed through a gland 37 and through the bore 28 
illustrated in FIG. 5, which provides for guiding and supporting the 
spindle 27. In the event of failure of the O-ring 30 or in the event of a 
leak occurring, the gland 37 can be replaced by a service gland 38 which 
ensures sealing integrity of the control valve by means of two further 
O-rings 39 and 40. That makes it unnecessary to remove and dismantle the 
control valve to replace the defective O-ring 30. 
FIG. 7 shows another embodiment of the flow control valve according to the 
invention, in which the drive (not shown) for the control member 4 is on 
the side of the control member 4, that is remote from the pressure 
regulating member 9. That results in the control valve being of a simpler 
design configuration as the drive, that is to say for example the spindle 
27, no longer has to be passed through the pressure regulating member 9 
and the pressure chamber 15 and thus the above-described sealing problems 
as between the pressure chamber 15 and the space between the throttle 
locations no longer occur. 
Also shown here is an inlet chamber 1 through which the flow medium flowing 
in the x-direction 2 passes into the flow control valve and an outlet 
chamber 3 through which the flow medium leaves the flow control valve in 
the same x-direction 2 again. Also disposed between the inlet chamber 1 
and the outlet chamber 3 are again the above-described two throttle 
locations which are connected in series. The first throttle location is 
formed by the control member 4 co-operating with a first valve seat 5. The 
second throttle location is formed by the pressure regulating member 9 
co-operating with a second valve seat 10 of the valve insert 7. The 
pressure in the inlet chamber is identified by pi the pressure between the 
two throttle locations is identified by p.sub.2 and the pressure in the 
outlet chamber is identified by p.sub.3. 
The pressure regulating member 9 is connected to the valve housing 6 by way 
of a resilient diaphragm 13. Control of the pressure acting between the 
throttle locations is in this case also made possible by virtue of the 
fact that on the one hand the input pressure p.sub.1 and on the other hand 
the pressure p.sub.2 acting between the throttle locations acts on the 
diaphragm 13. In order to achieve that effect, the inlet chamber 1 is 
communicated by way of a bore 34 in the valve housing with a pressure 
chamber 15 which acts on the diaphragm 13 and on the pressure regulating 
member 9. The pressure p.sub.1 thus exerts on the pressure regulating 
member 9 a force F.sub.1 acting in the negative y-direction 12. On the 
other hand the pressure p.sub.2 exerts on the pressure regulating member 9 
a force F.sub.2 acting in the positive y-direction 12. The operative 
surface A.sub.1 at which the pressure p.sub.1 acts on the diaphragm 13 or 
on the pressure regulating member 9 is of equal size to the operative 
surface A.sub.2 at which the pressure p.sub.2 acts on the diaphragm 13 or 
on the pressure regulating member 9. The resulting force F.sub.1 -F.sub.2 
is therefore directly proportional to the differential pressure p.sub.1 
-p.sub.2. A control spring 16 operatively disposed between the valve 
insert 7 and the pressure regulating member 9 exerts a force F.sub.R 
acting on the pressure regulating member 9 in the positive y-direction 12. 
The degree of opening of the opening 11 is so set that the forces F.sub.1 
-F.sub.2 and F.sub.R are of the same magnitude, in principle therefore as 
described with reference to FIG. 1. 
The operative surface A.sub.1 at which the pressure p.sub.1 acts on the 
diaphragm 13 or on the pressure regulating member 9 extends in a radial 
direction substantially between the two apex points S.sub.1 and S.sub.2. 
The rotationally symmetrical structure of the entire flow control valve 
means that the water flows through the second throttle location over the 
entire angular range of 360.degree. so that consequently the stroke of the 
pressure regulating member 9, which is necessary for the control action. 
becomes minimal. A variation in the position of the pressure regulating 
member 9 as a result of a variation in the outer pressure difference 
p.sub.1 -p.sub.3 thus results in the smallest possible stroke variation 
and thus the smallest possible variation in the force F.sub.R applied to 
the pressure regulating member 9 by the control spring 16 and thus the 
smallest possible variation in the operative pressure p.sub.1 -p.sub.2 
which determines the throughflow. 
Guidance for the pressure regulating member 9 in the y-direction is also 
ensured on the one hand by vanes or ribs 17 co-operating with the valve 
insert 7 and on the other hand by vanes or ribs or simply by a cylindrical 
extension portion at the other end of the pressure regulating member 9, 
which engages into a recess in the valve housing 9 and is supported there 
with as little friction as possible, with the flow medium flowing 
therearound. 
The mass of the pressure regulating member 9 can be increased by means of a 
ring 19 which is fitted onto the pressure regulating member 9. consisting 
for example of brass, copper or sealed lead, and thus the resonance 
frequency of the possible oscillations can be reduced. As a result the 
resonance frequency is lower than the excitation frequencies produced by 
the flow. 
The pressure p.sub.3 also acts on the diaphragm 13 and applies a force 
F.sub.3 acting on the pressure regulating member 9 in the positive 
y-direction 12. To compensate for that force F.sub.3 the pressure 
regulating member 9 has an extension portion 20 at which the pressure 
p.sub.3 compensates for that force, just as already described 
hereinbefore. 
The embodiment shown in FIG. 7 is suitable in particular for heating 
systems in which a low structural depth is required. That is advantageous 
for example for heat exchangers. Here too a vertical feed of the flow 
medium is possible (as illustrated for the first control valve in FIG. 6) 
if the drive for the control member 4 is taken out laterally for example 
by means of an angle transmission or magnetic drives are used.