A CONTROL VALVE

The prior art

The present invention relates to a control valve, where the valve may be set for a flow which is kept constant independent of pressure changes in the system in which the valve is incorporated.

The control valve may advantageously be used in liquid-borne systems, such as for instance in central or district heating systems, but generally everywhere where it is desired to have a presettable valve which keeps the flowing amount of liquid constant.

An example of a valve which is described in the known literature, may be found in GB1164237 (Self), in the valve of Self, the flow of liquid is controlled by means of a rotary knob connected with a channel which may be pushed into and out of the liquid flow channel in the valve.

Thus, the valve of Self makes it possible to control the amount of liquid which flows through the valve. If, however, changes occur in the pressure in the system in which the valve is incorporated, it will no longer be possible to count on the preset amount of liquid.

Another example of a valve which is described in the known literature, may be found in US5174332 (Yokoyama). The valve of Yokoyama is a constant flow valve, where it is attempted to keep the flow of liquid at a constant level. The valve comprises a spindle.

Like with the other known valves, it is not possible to ensure with the valve of Yokoyama that the flowing amount of liquid is kept at a constant level, even if pressure changes in the system take place.

Thus, no control valve is available, where the flow through the valve may be kept constant independent of unforeseen pressure changes.

The object of the invention

The present invention remedies the problems of the most immediate prior art by providing a control valve, where the flow through the valve may be kept constant independent of unforeseen pressure changes.

Thus, the invention relates to a control valve for use in liquid-borne systems, such as for instance central or district heating systems or other systems, in which there is a need for presetting the flow of liquid to a constant level which does not change, even if unforeseen pressure changes in the system take place. The control valve comprises a valve housing in which a differential pressure regulator and a presetting device are arranged. The differential pressure regulator maintains a constant differential pressure between the inlet side and the outlet side by means of a spring force.

The presetting device is used for the presetting of the flowing amount of liquid and comprises a rotary grip, a spindle, an outer cylindrical valve element and an inner valve element. The outer valve element has a slit through which the liquid may flow. The inner valve element is disposed in the cylindrical valve element and has a lower skirt of curve shape. Further, the valve element is connected with the rotary grip by means of the spindle, so that the opening in the presetting may be changed by rotation of the rotary knob.

When the presetting device is provided with indications on the rotary grip, the flowing amount of liquid may be observed at a given position of the ro- tary grip.

When the presetting device is disposed on an axis having an acute angle relative to the flow channel, stress in the valve is reduced, and, together with the skirt of the inner valve member, an effective presetting device is achieved.

The drawing

Exemplary embodiments of the invention will be explained more fully below with reference to the drawing, in which

fig. 1 shows a control valve, and

fig. 2 shows the individual valve components separated.

Description of the exemplary embodiments

With reference to fig. 1 , a cross-section of the control valve is shown. The control valve comprises a valve housing 2, in which a differential pressure regulator 3 and a presetting device are arranged.

The flow of liquid takes place in the flow channel which connects the inlet side, where the liquid runs into the valve, with the outlet side, where the liquid runs out of the valve.

The presetting device comprises a rotary grip 14, a spindle 9, an outer cylindrical valve element 6 and an inner valve element 7. The outer valve element 6 has a slit through which the liquid may flow. The inner valve element 7 is positioned in the cylindrical valve element 6 and has a lower skirt 8.

The skirt 8 imparts a curved shape to the lower part of the inner valve ele-

ment 7, so that the length of the valve element will have an angular dependence.

When the inner valve element 7 is disposed in the outer one 6, it may be rotated about its own axis.

The inner and outer valve elements cooperate such that when the inner valve element 7 is rotated, the skirt 8 will be rotated and open or close the slit in the outer valve element 6. The rotation may take place continuously between the closed and opened outer positions.

The inner valve element 7 is connected with the rotary grip 14 by means of the spindle 9. This means that the setting of the flowing amount of liquid takes place by rotation of the rotary grip.

The presetting device has indications on the rotary grip which show the flowing amount of liquid at a given position of the rotary grip. For instance, the indications may consist of one or more straight lines on the rotary grip in combination with figures or symbols on the valve housing. <

It is possible to have indications on the valve, as, from the outset, it is independent of unforeseen pressure changes, so that the amount of liquid to which the rotary grip is rotated, may be counted on precisely.

The presetting device and the differential pressure regulator are seated on the same axis opposite each other. The axis is inclined relative to the flow channel which connects the inlet side and the outlet side.

The differential pressure regulator 3 comprises a pipe connection and a spring. The pipe connection transfers the pressure in the flow channel to the differential pressure regulator.

In a control valve comprising a differential pressure regulator, a balance emerges between the inlet pressure and the outlet pressure plus a spring force, so that the differential pressure corresponds to the spring force. With a given spring force, this differential pressure will therefore be constant.

The differential pressure regulator and the presetting device surprisingly ensure that the amount of liquid flow to which the valve is preset, will be maintained during the entire operation of the valve. Even in case of externally produced pressure changes in the system in which the valve operates, the amount of liquid will be kept at a constant flow.