TECHNICAL AREA OF INVENTION

The present invention is intended to ensure at a relatively low difference of pressure a single direction flow of flowing gases and fluids in pipelines and ducts. This type of device is normally called a check valve and is used amongst other things to ensure that different gases and fluids in pipelines, tubes, hoses and other ducts can only flow in one direction. The invention can be applied to ventilation ducts in factories, hotels and residential property where smoke and combustion gases must be stopped from spreading from a blaze at the seat of the combustion to other rooms and premises, whether the fan installation in the building is working or not.

Check valves according to said invention can also be applied to sewers, ground and drainpipes as a backflow preventer and to block odours from outside sewers and congested rainwater pipes, also to prevent vermin invasion from sewers.

The inventive conception, if using special durable material with long-service life can also be used as artificial cardiac valves for human beings.

KNOWN TECHNIQUE AND INVENTIVE BACKGROUND

During the history of technique a large number of products and methods have been developed whose aim has been to control the flow of gases and fluids in one direction only. The following are to be found among ordinary constructions: shaft or sliding disk valves, vah/e flaps, rubber membranes fixed to given spots, ball-steered check valves, bird's throat-like valves of rubber, cycle-tyre nipples with valve rubber tubing, etc. However there is still much to develop to eliminate the occurrence of flow disturbance and to minimize internal fall in pressure in the check valve and to ensure optimal water- tightness and a reliable automatic function also after long use.

DEMANDS AND REQUIREMENTS FOR NEW TECHNIQUE

Each manufacturer would probably make reasonable demands for an inexpensive manufacturing process with moderate tolerance requirements, while the user, besides good functioning, also emphasizes the importance of a straight laminar flow for the least possible flow-resistance and loss of energy. Further the check valve should be silent, tight and reliable at the same time as being simple and cost-effective to install and to maintain or exchange on the spot.

Said invention meets these requirements, at least within the framework of lower working pressure. A check valve with optimal form and material qualities according to said invention can, at least theoretically, meet a through flow without a measurable drop in pressure. A backflow preventer/nonreturn valve which in principle is quite watertight in a pressureless state and where water-tightness is reinforced on increasing counter pressure is another advantageous quality. SHORT DESCRIPTION OF SAID INVENTION

A preferred model according to said invention contains an inset which can be placed inside an existing pipe at the most convenient flange joint. This type of inset can be made wholly or partially of injection-moulded rubber or of elastic thermoplastics and have different types of reinforcing or webbing. The inset is supplied on the inside with a sloping wall in the longitudinal ireetion of the pipe or flexible membrane aslant, one end of which is placed near the periphery of the tube and the flange joint, while the membrane widens in breadth towards the other end, preferably in the middle of the pipe, where the broadest part of the membrane on the aslant is profiled to reach the surrounding pipe's inner side in order to be sealed against this. In order that the cylindrical framework of the inset will not implode through occurring fluid or gas pressure this component should be reinforced or stabilised by sufficient thickness of the material of the wall. It is an advantage on higher working pressure that the membrane is constructed of webbing-reinforced rubber for example, which is vulcanized and attached to a cylindrical framework of some kind of metal.

According to said invention another design of a non-return valve can consist of a single flexible or easily deformable detail, here called a "slanting" membrane, apart from a surrounding casing belonging to it with contact flanges or threaded connections at the ends and with grooves or slits in the encasing jacket to which the membrane is fixed in a suitable way. To achieve qualities of absolutely closed backflow or the lowest possible opening pressure on normal feed flow, the membrane can be arranged in different ways and be manufactured of more or less flexible, pre-formed or reinforced material.

A third design has been set up for possible use as an artificial cardiac valve or heart valve, which makes uses of the biological tissue as a surrounding wall at least partly, and the flexibility of the tissues as a contributory resource to achieve an easily influenced membrane for the shutting and opening movements of the cardiac muscles.

A check valve according to said invention consists of an easily deformable and against the direction of flow "yawning" and extremely slanting membrane with reinforced, alternatively non-reinforced, rubber sheeting or flexible plastic or of stainless spring steel foil or other suitable materials where the membrane is constructed in a skewed direction inside a round, oval or many-sided casing, tube or jacket, so that the membrane at its widened end near the check valve's discharge end can be shaped or allow itself to be shaped in sealing contact with the opposite inside of the casing or pipe and that the membrane's other and narrowing end diagonally to the check valve's pressure and Inlet side has sealing contact with the opposite inner side of the casing so that a V-shaped pocket is formed at the check- valve's discharge side, while the membrane on the check valve's inlet side forms a skewed area which can wholly or partially be pressed aside by the pressure of admission gases or fluids. DESCRIPTION OF SOME DESIGNS ACCORDING TO ATTACHED DIAGRAMS Some designs of device will be further described with reference to figures 1 -5 Figure 1 shows in longitudinal section a method and device intended in a jointed pipe for liquids or gases to achieve blocking against undesirable backflow.

In the pipe(l)an introduced inset (2) of injection-moulded plastic or rubber, etc is provided with a flange or collar (3) in inset's inlet end (4) and a cylinder element or casing extending from the flange(5) with a slanting flexible wall or skewed membrane inside the casing(6), whose jacket area (7) is shaped in a semicircle- or arc where the furthest free and sealing ends (8) are shaped to fit and make sealing contact with the surrounding pipe's (1) inside. Said membrane (6) can be supplied with grooves or be reinforced (9) with steel wires or webbing or be undulated in said membrane's longitudinal direction for strength and flexibility in desired directions. The shape and pre-stressing plus elasticity of said membrane can be adapted so that sealing against backflow can be achieved already in said membrane's neutral position. Said membrane is deformed and is opened by the pressure from admission gas or fluid so that said membrane is buckled in diametrical direction (10) from its neutral or sealing position. When pressure ceases said membrane should preferably be able to spring back of its own accord to its backward-sealing function position. For this purpose can probably a flexible projecting pin from one side of said membrane (11) or similar, which reaches the inside of pipe, initiate springing back to said membrane's neutral position.

Said inset according to figure 1 can alternatively have a floating position in said pipe so that said inset can be fixed in optional position. Said flexible membrane is vulcanized onto a short angle-cut piece of piping which can be screwed or clamped tight onto the outer fixed pipe. To stop leakage into the split between the partially cylindrical inset and the outer pipe's inside rubber sealing can be placed round the inset.

Figure 2 shows a perspective diagram of design of a complete check valve according to said invention, where said slanting flexible membrane (6) is formed of a hard but thin foil of suitable material with regard to heat resistance and elasticity, where the membrane jacket area (7) is initially shaped like the casing shape or the pipe's (1) inside and is fixed to the surrounding casing (1) through a fluted or laser-cut slit (12), to which said foil or membrane is glued or clamped in a suitable way to casing (1 ) wall.

Figure 3 shows design of an aspect in said pipe's longitudinal direction where said skewed membrane (6) is shaped in a hard and thin metal foil, the jacket area of which is somewhat folded in a fan shape and elastically rounded at the sealing position (8) and fixed to the surrounding casing in a laser angle- cut slit (12) in which the foil is glued diagonally opposite the jacket (1) plane so that said membrane is biased against its sealing or protuberant position.

Figure 4 shows a cross section of a design where said skewed membrane (6) is formed of a foil, that is elastic and somewhat folded and rounded against the surrounding casing also glidingly or floatingly aligned to surrounding casing in a distance-cut or laser-cut split (12), in which the foil or membrane can slide between the end positions which are marked or limited by edging (13, 14) that is vulcanized to the foil on both sides of the pipe wall (1). This partially leaking construction has the advantage that the membrane is more easily deformable also at low working pressure.

Figure 5 a-c shows in three aspects a modification of said invention where said check valve is designed for use as an artificial cardiac valve. In this case it is not only the skewed membrane that is elastic and flexible but also those parts of the casing (1) that secure the membrane (6).

Figure 5 a is a transverse aspect that shows that the casing (1) has a flat arcuate cross section which ought to increase the check valve's length of life considerably. Figures 5 b-c make up two lateral aspects towards the narrow and broad sides respectively of the cardiac valve.

ALTERNATIVE DESIGN DETAILS

For the said skewed membrane to be easily deformable and have good sealing qualities at the same time also near the sealing end (8), it can be advantageous if said membrane at its attachment to the pipe (1) or inset (2) is prepared with a crease or hobbed groove on either side of said membrane, which gives said membrane a more pliant flexure in both deflection directions.

So that said skewed membrane shall seal well at the sealing end (8) it is advantageous if the pipe (1) is ovally arcuate according to figure 5 a.

The sealing Hp can to advantage be widened if said membrane is allowed to protrude in front of the outer attachment. This arrangement can eliminate any occurring leakage nearest said membrane's edges on a level with the beginning of (8) the sealing lip.

If said membrane's skewed gradient does not follow a straight line but is somewhat bent in a convex or concave arc, then said membrane's resistance to deformation in any direction can be affected.

Said membrane can be attached to the pipe (1), casing or inset (2) in different ways. For example said membrane can be clamped round the pipe (1) with the slit 12) divided into two halves.

It is not necessary for said membrane (6) in neutral position to seal against the surrounding pipe (1). On certain backflow pressure said membrane will all the same be pressed against the inside of the pipe and will seal.

An expert in the field would realise that details and devices according to the conception of said invention can be constructed in many more ways within the framework of the conception of said invention.