A cover of this kind is known for closing an open- ing in a wall in a hydraulic vortex regulator, in which the locking device comprises a threaded rod hinged to. the wall and pivotable into a fork member on the cover, following which a nut with a control arm can be tightened against the fork member and thereby close the cover in a closed position.

GB-A-2 271 438 discloses a vortex regulator having a cover in an end wall. This cover is pivotal about an axis perpendicular to the plane of the sealing surface.

Covers of the type mentioned are provided for the purpose of making it possible to inspect the interior of the regulator, to replace members mounted in the interior, like for instance orifice members and guide members, to provide a by-pass in case of clocking and/or to observe the formation of vortexes in the regulator.

To make such an inspection or by-pass cover suit- able for serving all these purposes, it has to be simple and quickly operable and it should preferably be operable from the ground (the vortex regulators are mounted in sewers, wells and the like).

The object of the present invention is to provide

a cover, which is easy to operate.

This object is met by a closure of the type men- tioned by way of introduction, which is characteris- tic in that the locking device comprises an engage- ment member on the wall with a lower engagement sur- face facing the wall, and a hook member and an arm, both being pivotal about a pivot axis, which is sub- stantially in parallel with the plane of the sealing surface, the hook member and the arm being mutually connected in such a manner that the arm by a movement away from the wall can swing the hook member between a locking position, in which the hook member engages the lower engagement surface, and an opening posi- tion, in which the hook member releases the lower en- gagement surface. Hereby is obtained that a pull in the arm will first release the locking engagement of the hook member with the engagement member and then open the. cover.

The locking device comprises preferably a cam mem- ber which is pivotal about the pivot axis of the arm and the hook member, the engagement member comprising an upper engagement surface facing away from the wall, and the cam member being connected with the arm in such a manner that the latter can swing the cam member and force it against the upper engagement sur- face, when the hook member is in its opening posi- tion. This makes it easier to open the cover in case of a water pressure on the outer side of the cover or in case of the cover adhering to the wall.

In a practical, advantageous and simple embodiment the arm is integral with the hook member and/or the cam member.

The pivot axis of the arm and the hook member and of the cam member, if present, may be in parallel with the hinge axis. This makes it possible in a sim- ple manner to design the closure such that the cover has a centre axis extending perpendicularly to the direction of the hinge axis and the pivot axis, and

the closure comprises a frame having two side members extending on either side of the centre axis and con- stituting at one end a part of the hinge and carrying at the other end a shaft defining the pivot axis of the arm, the hook member and, if present, that of the cam member. Preferably, an arm, a hook member and, if necessary, a cam member are provided at each frame side member. This ensures a distribution of the clos- ing and opening forces on the cover.

The arms may suitably be connected by a handle.

A control member, for instance a hinged rod, is preferably connected to the end of the arm opposite the pivot axis. This makes it possible to operate from a distance, for instance from the ground. Alter- natively, a cord and pulley may be used, or a rod with a hook, like for instance a boathook.

In one embodiment, the engagement member is a plane, annular member with a bottom side facing the wall and a top side facing away from the wall, the lower engagement surface being part of said bottom side and the upper engagement surface being a part of said top side. This embodiment is preferably used, if the wall is conical.

In another embodiment the engagement member is a plane, annular member with a bottom side facing the wall and a top side facing away from the wall and a portion, which is raised relative to the top side, the lower engagement surface and the upper engagement surface being areas of said portion. This embodiment is preferably used, if the wall is plane.

The invention will be explained in more detail in the following by means of examples of embodiments with reference to the schematic drawings, in which Fig. 1 is a lateral view of a vortex regulator ac- cording to the invention, Fig. 2 is a detailed view of the closure according to Fig. 1, Fig. 3 is a view of the closure seen in the direc-

tion of the arrow III in Fig. 1, Fig. 4 is a view corresponding to Fig. 2, but showing another embodiment, and Fig. 5 is a view corresponding to Fig. 3 of the embodiment in Fig. 4.

In Figs 1-3 a conical vortex regulator 1 is shown with an inlet 2, an outlet 3 and an axis 4, about which a vortex will be formed in a flowing liq- uid, when the regulator starts functioning.

The vortex regulator 1 has in a conical end wall 5 opposite the outlet 3 and openable closure 6, the more detailed construction of which being the subject matter of the present invention. The end wall is shown in section in Fig. 2.

A flat, annular engagement member 7 is welded to the end wall 5 at an opening therein and comprises a sealing surface for a cover 8 and a lower engagement surface 9 and an upper engagement surface 10, which will be described in detail below.

The cover 8 consists of a flat plate, which may be of any suitable material, but it may be transparent with a view to making it possible to inspect the in- terior of the regulator during normal operation. The cover 8 may thus be made from for instance transpar- ent acrylic plastics or steel sheet. The cover is fastened by means of screws 11 to a frame comprising side members 12, which are held together by interme- diate members 13.

A shaft 14 is welded on an edged, protruding side of the annular engagement member 7, said shaft acting as a hinge tap, the ends 15 of which being passed through holes in one end of the side members 12.

At the opposite ends the side members 12 carry be- tween them another shaft 16. An arm member 17 is journalled on this shaft at each side member 12, said arm member comprising an arm 18, a hook 19 and a cam 20. A washer 21 is journalled between the respective side member 12 and the adjacent arm member 17. A

transverse handle 22 is mounted between the ends of the arms 18.

In Fig. 2 the closure 6 is shown in its closed po- sition, in which the hooks 19 keep the cover 8 closed by their engagement with the lower engagement surface 9. To open the closure 6, as shown by the broken in Fig. 1, it is only necessary to lift the handle 22.

Thereby, the hooks 19 will be swung out of engagement and away from the engagement surface 9, whereas the cams 20 will be swung down to abutment against the upper engagement surface 10, and by a continued pull in the handle 22, the cams 20 will press against the upper engagement surface 10 and by means of the prin- ciple of the lever assist the force from the pull in the handle 22 in raising the cover 8. This may be ad- vantageous, if a sealing ring 23 on the bottom side of the cover 8 adheres to the sealing surface on the engagement member 7 or if water. is impounded above the vortex regulator 1.

As indicated by a broken line in Fig. 1, a rod 24, which is hinged to the handle 22, may be used for opening the closure from the ground, if for instance the vortex regulator 1 is mounted in a well and water is impounded in the well.

Figs 4 and 5 show an embodiment, which is suitable for use in connection with a vortex regulator with a plane end wall 5a.

The engagement member 7a is at the locking device provided with a bent up edge portion 25, from which a finger 26 extends to each respective side to estab- lish the lower engagement surface 9a and the upper engagement surface 10a. The positioning of the shaft 16 has been correspondingly changed. Apart from that the construction and the functioning correspond to the embodiment shown in Figs 1-3.