This invention relates to an automatic, float-operated vent or air relief valve of the kind indicated in the preamble of the attached patent claim 1.

Vent valves of the kind indicated above are predominantly used in hot water circulation systems for venting air separated from the water of the system. Examples of vent valves of the above indicated, general kind are disclosed for instance in Swedish patents Nos. 208 498 and 221 142, but said valves are not suitable for mounting directly to a radiator, since their design makes them comparatively bulky. The reason for this is that by the pressures existing in the systems of the kind in question, i.e. up to a maximum of approximately 4 bar, said valves must be designed having a relatively large float in order to provide sufficient weight for the float to ensure that it securely opens the valve when necessary, within the entire pressure range for which it is intended. If the float is too light in relation to the pressure in the system the valve may remain closed, so that no venting takes place.

However, a great number of automatic vent valves are previously known, which are intended to be attached directly to a radiator, and examples of such valves are disclosed in US patent specifi¬ cations 2 153 726, 2 314 963, 2 467 217 and 3 088 482. All of these known valves have the same basic design, i.e. they are designed as a nipple which may be screwed directly into the radiator or the like and which comprises an inner bore at one end communicating with the system and which at the other end commu¬ nicates with the atmosphere through a number of expanding washers or hygroscopic washers. The basic function is that the valve seals as long as the hygroscopic washers are moistened with water but permit venting when the washers become dry. In several cases such prior art vent valves are also provided with quick venting means which in such cases are manually operated. One of the disadvantages of such known vent valves is that since they

operate without any float there is no space in the valve where the air may be collected, which means that the water in the system continuously is in contact with the expanding washers. This in turn means that the water level in the radiator must be lowered relatively much before the washers become dry and are able to vent the air. Another disadvantage of such vent valves for radiators is that when filling the system as it is taken into operation for the first time or after service, the aperture or opening of the valve must, at least towards the end of the filling, be very small in order to secure that the water leak by each valve does not become too large before the washers expand so that the valve seals. This in turn brings about the dis¬ advantage that, for the purpose of permitting quick venting in the initial stage of the filling, the valves will have to be adjusted manually during and after the filling of the system, which may involve rather extensive work in a case when the system comprises for instance a great number of apartments on different stories.

The object of the present invention is therefore to provide an automatic vent valve of the kind indicated in the introduction, which is adapted for mounting in association with a radiator and which permits reliable venting of small as well as large quantaties of air without any manual adjustment.

According to the invention this object is achieved by means of a vent valve of the kind indicated in the characterizing portion of the attached claim 1.

Advantageous further developments of the invention are indicated in the dependent claims.

Other features and advantages of the invention are described in the following detailed specification, referring to the enclosed drawings, on which:

Fig. 1 illustrates the vent means according to the invention in a longitudinal section,

Fig. 2 illustrates a cross-section through the float housing of the vent valve according to Fig. 1, taken along the line II-II in Fig. 1, and

Fig. 3 in a partially sectioned side view illustrates the vent valve according to Fig. 1 provided with a protec- tive cover and mounted on a connector.

With specific reference to Fig. 1 it is illustrated that the vent valve 1 according to the invention consists of a housing 2 which forms a float chamber 3 with a float 4 guided therein, said float being more closely described below. From Fig. 2 it is clear that in the illustrated embodiment the float chamber as well as the float have a cylindrical shape, but it is obvious that other designs permitting a reliable guiding of the float may be employed as well.

In the illustrated embodiment the lower end of the housing 2 is provided with an external thread adapted to engage an internal thread provided in a bottom piece 5 forming the bottom of the float chamber 3 and simultaneously being provided with an aperture 6 intended for communication with the fluid to be vented. For the purpose of providing a reliable seal between the housing 2 and the bottom piece 5 a seal 7 is suitably provided therebetween, as illustrated in Fig. 1. In the illustrated embodiment the bottom screw is provided with a screw connector 9 having an external thread and having the communication aperture 6 extended therethrough. Said screw connector 9 is intended for the installation of the vent valve 1 either directly in a not illustrated conduit or by means of a connecting piece 8 illustra¬ ted in Fig. 3, for instance for the attachment to a radiator.

The float chamber 3 in the housing 2 is delimited upwardly by means of a partition wall 10 provided at a distance below the

upper end of the housing 2. In the partition wall a bore 11 is provided, which is preferably provided substantially in the longitudinal central axis of the float chamber 3. A nozzle 12 is mounted in the bore 12 and this nozzle is screwed into the bore 11 so that its lower end projects into the float chamber 3. Through the nozzle 12 a channel 13 is extended which in the float chamber opens in a vent orifice 13a. The channel 13 communicates with the interior of the housing on both sides of the partition wall 10 for controlled venting of the float chamber 3.

At the upper side of the partition wall 10, at a distance inside the bore of the housing 3 an annular, upwardly extending inner wall 14 is provided, and inside this inner wall are provided a number of expanding or hygroscopic washers 15 which are main- tained in position inside the inner wall 14 by means of a plug 16 screwed into the same. On a level with the expanding washers 15 the inner wall 14 is also provided with at least one discharge opening for drawing off air and possibly a smaller amount of water to the area outside the sidewall 14. Fig. 1 also illustra- tes that between the outside of the inner wall 14 and the upper portion of the wall 3 of the housing a collecting chamber 21 is formed for collecting a smaller amount of water that may penetrate the expanding washers before they expand and seal.

Fig. 2 illustrates that the float 4 has a shape, in this embodi¬ ment cylindrical, adapted to the shape of the float chamber 3, whereby the diameter of the float 4 is sufficiently smaller than the inner diameter of the housing 2 to permit air intended to be vented to pass between the float 4 and the inner wall of the housing 3. As will be discussed more closely below, it is, by this embodiment, of utmost importance for the operation of the valve 1 that the float 4 during its movement in the float chamber 3 is guided rectilinearly and that it is not tilted therein, and for that reason the float 4 is provided with a number of, in the illustrated embodiment three, guide beads 4a uniformly distri¬ buted around its circumference and extended in the direction of movement of the float 4 in the float chamber 3. In order to

secure the rectilinear movement of the float the guide beads 4a are provided such that their outermost ends are positioned on a circle the diameter of which is only slightly smaller than the diameter of the float chamber 3 in the housing 2.

At its upper end facing the vent orifice 13a the float 4 is provided with a seal member 18 intended to engage the lower end of the nozzle 12. It is vital for the function of the valve 1 that the seal member 18 is provided with an upper substantially flat seal surface 18a cooperating with the lower end of the nozzle 12 and thus with the vent orifice 13a and, at least in the position of the float 4 in which the seal surface 18a cooperates with the lower end of the nozzle 12, being inclined at an angle relative to the lower end of the nozzle 12. In the illustrated embodiment where the float is rectilinearly movable in the float housing, the lower end of the nozzle and thus the vent orifice are positioned in a plane perpendicular to the direction of movement of the float 4, whereby the upper surface 18a of the seal member 18 is inclined at an angle relative to the plane perpendicular to the direction of movement of the float. This angle may be determined from case to case and dependent on the conditions of the valve application, and is also determined in relation to the hardness of the material of the seal member.

In the illustrated embodiment the seal member is produced in the shape of an at least partially resiliently yieldable sealing peg having a head 18b positioned at the upper end of the float 4. The surface of the head 18b facing away from the float 4 forms the upper seal surface 18a. The sealing peg is also provided with a shaft 18c extended from the opposite surface of the head and being received in a mounting channel 19 opening at the upper surface of the float 4, whereby said channel is inclined relative to the longitudinal axis of the float, for positioning the seal surface 18a in said angular position.

For technical reasons relating to the production thereof the float is preferably solid, whereby the mounting channel 19

consists of a bore produced therein. For the purpose of in¬ creasing the buoyancy or net lift of the float the bore may be provided having an essentially greater length than that of the shaft 18c of the seal member 18.

As mentioned above, the seal member is, in this embodiment, manufactured from a resiliently yieldable material, such as rubber, whereby the hardness of the rubber is adapted to the pressure range of the valve such that within the intended pressure range the vent orifice 13a, for reasons clarified below, will never be completely closed by the seal member and that an opening remains which varies dependent on the depression of the lower nozzle end into the seal member, and thus on the pressure.

Fig. 3 illustrates an embodiment where the vent valve 1 has been supplemented with a covering cap 20 attached to the bottom piece 5 by means of a snap-in connection and being provided with vent orifices 22 in the upper area of its sidewall.

In Fig. 3 the vent valve 1 is furthermore illustrated mounted to a connection piece 8 employed when installing the valve 1 in a horizontal opening, such as in a radiator, since the valve in itself has to b mounted vertically due to the fact that it is float-operated. The connection piece 8 is provided with a cut-off member 8a permitting the connection to the radiator to be cut off in the cases when the valve 1 has to be dismounted for exchange or maintenance.

The operation of the vent valve 1 will now be explained in greater detail. In float-operated valves of this kind the dimensioning of the float is governed by the pressure range within which the valve is intended to operate, i.e. the float must on one hand have sufficient buoyancy or net lift, but must on the other hand have sufficient weight to release the vent orifice when the water level sinks. As has been mentioned in the introduction, the vent valve according to the invention is primarily adapted for use at radiators and the like where the

working pressures are up to a maximum of 4 bar, which means that a conventional float-operated vent valve intended for this pressure range would be too bulky to be used on the radiator. If, on the other hand, the valve was designed in accordance with known principles but in a smaller dimension, this would mean that in the upper pressure range the float would completely seal the vent orifice and would make venting impossible as long as the pressure reamined at this high level. In order to eliminate this problem it is therefore suggested in accordance with the inven- tion to provide the upper seal surface 18a of the seal member 18 inclined relative to the vent orifice 13a, which means that the vent orifice 13a is never completely closed, whereby venting is guaranteed within the intended pressure range. Even if, in the illustrated embodiment, the upper seal surface 18a is illustrated inclined relative to the plane perpendicular to the direction of movement of the float 4, the same function will naturally be obtained if, instead, the vent orifice 13a in the lower end of the nozzle 12 is inclined and the upper seal surface 18a is provided in the plane perpendicular to the direction of movement of the float.

Installed in a hot water circulation system or the like, with the system in operation, the vent valve according to the invention serves to collect air from the water in the system in the float chamber 3, above the float. This air collected in the float chamber is continuously vented due to the fact that the vent orifice 13a never becomes completely closed. When the water level rises in the float chamber 3 a smaller amount of water may be withdrawn through the vent orifice 13a, and if this amount of water is large enough it will dampen the expanding washers 15 sufficiently for these to swell and seal so that no further water may be withdrawn. As soon as the expanding washers have dried again, venting takes place once more.

The inclination of the seal surface 18a of the seal member 18, as suggested according to the invention, does in combination with the resiliency of the seal member result in the advantage that

regardless of the pressure existing in the system water can never flow out through the valve at a faster rate than to be safely collected in the collecting chamber 21, before the expanding washers 15 expand and seal against continued escape of water. As has been mentioned above, this is achieved by the fact that up to the maximum allowed pressure the vent orifice 13a will be restricted, through the depression of the nozzle into the seal member 18, directly dependent on the pressure in the system. Above the allowed maximum pressure the vent orifice 13a will on the other hand be completely closed so that no venting occurs anymore.

This leads to a particular advantage in connection with filling such a system, since the relatively large vent orifice 13a will remain completely open during the filling, which is desirable in order for the filling to be carried out relatively quickly. As soon as water approaches the upper level in the system and enters the vent valve, the float will rise and the vent orifice 13a will thus, as has been mentioned above, continuously be restricted as the pressure builds up. It is thereby also possible, during the filling of the system, to eliminate the danger of too large a water leak at the vent valves, and this without any demand for manual adjustment of the valves. This is an important andvantage in relation to known vent valves for radiators, which, as has been mentioned in the introduction, require manual restriction of the venting when the system comes closer to being filled. It is obvious that such a manual adjustment requires much work in systems containing a great number of vent valves being provided for instance at different stories and being filled one after another when filling the system. Thus, the objects set in the introduction are achieved by means of the described vent valve.

Although the invention has been described above with specific reference to a presently preferred embodiment thereof, it should be obvious that the invention is not restricted to this specific embodiment but that modifications obvious to a man skilled in the art may be performed without departing from the scope of the

invention. As an example, the invention is in its broadest scope not restricted to the rectilinear movement for the float, but this may also perform a swinging movement towards the nozzle when the water level rises. However, it is a requirement that an inclination or angle exists between the lower end of the nozzle, i.e. the vent orifice, and the seal surface of the seal member in the position of the float causing cooperation between the lower end of the nozzle and the seal surface of the seal member. Thus, the scope of the invention shall only be restricted by the enclosed patent claims.