Non-return valve for bore hole sleeves

Details Non-return valve for bore hole sleeves Non-return valve for bore hole sleeves

1986-07-25

1987-12-01

Taylor, Dennis L.

Hydraulic and earth engineering

Earth treatment or control

Chemical

137847, 166151, E21D 2100

Patent

active

047100630

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a non-return valve for bore hole sleeves which are intended for injection of a sealing and/or reinforcing compound into rock cracks and similar cracks and which comprise a rigid case, one end of which is provided with means for detachable connection to the case of a pump hose for the compound to be injected, as well as an expandable device for securing the rigid case in the bore hole.
When bore hole sleeves are used, said sleeves are first fixed by means of the expandable device in holes that have been bored in the rock. The sealing and/or reinforcing compound is then injected through the bore hole sleeves into the rock crack. The bore hole sleeves have to be provided with a non-return valve of some type to prevent the compound from flowing back through the bore hole sleeves, when the pump pressure ceases.
The non-return valves which hitherto have been used in connection with bore hole sleeves have comprised a movable mechanical valve means, for example a ball, as disclosed in the German Patent Application No. 2 402 509. A non-return valve of this type has two disadvantages. Firstly, it is difficult to achieve a reliable operation of the valve means during the heavy working conditions prevailing during injection of, for example, cement grout or a similar sealing compound under high pressure into rock cracks. Secondly, the valve element obstructs the injection of the compound due to the fact that the flow area of the bore hole sleeve is reduced. It is particularly difficult to use a ball valve as non-return valve in connection with a bore hole sleve of the type disclosed in the Swedish Patent Application No. 8204256-5, where a blocking means is provided at the exit end of the bore hole sleeve to enable the establishment of an initial pressure in the bore hole sleeve to actuate the expandable means. The blocking means is then forced out of the bore hole sleeve by further increasing the pressure in the bore hole sleeve. Furthermore, non-return valves comprising balls or other movable valve means and corresponding valve seats are expensive to manufacture.


SUMMARY OF THE INVENTION

The main object of the invention is to provide a non-return valve which does not have the above mentioned disadvantages. According to the invention, this is achieved by giving the non-return valve the features set forth in the claims.
Due to the fact that the non-return valve is an elastic sleeve into which the rigid case of the bore hole sleeve runs and which is adapted for automatical contraction, when no compound is being injected, a reliable valve operation is achieved and a flow area for the injected compound in the non-return valve is provided which has substantially the same size as the flow area in the rigid case of the bore hole sleeve, so that the non-return valve does not obstruct the injection of the compound into a rock crack. Due to the fact that the elastic sleeve is expanded and contracted, no movable valve means with valve seats are required, thus increasing the reliability of the operation of the non-return valve and substantially reducing the manufacturing cost of the non-return valve. Particularly by providing contraction means at the free end of the elastic sleeve in such a way that they cause a flattening of the exit end of the elastic sleeve, a very reliable valve operation is achieved, because the backward flow of the compound conduces to the compression of the mouth of the elastic sleeve.


BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of a non-return valve according to the invention will now be further described below with reference to the accompanying drawings.
FIG. 1 is a longitudinal section of a bore hole sleeve which is inserted into a bore hole and which has a non-return valve according to the invention and an expandable device.
FIG. 2 is a longitudinal section of the bore hole sleeve shown in FIG. 1, the section being rotated 90.degree. in relation to the section of FIG. 1 and the sleeve being fixed in the bore hole by means of the ex

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patent: 3422844 (1969-01-01), Grise
patent: 4260295 (1981-04-01), Yestlund
patent: 4607663 (1986-08-01), Raftis et al.

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