Device for closing road wells in vehicle and pedestrian areas

Abstract: A device for closing road wells in vehicle and pedestrian zones is provided, said device comprising a support frame (2) defining an access opening (4) and a plate-like closing element (5) rotatably engaged with the support frame (2) about a hinging axis (6) so as to be movable between a raised open position and a lowered closed position.

Description: The present invention relates to a device for closing road wells in vehicle and pedestrian areas, of the type disclosed in the preamble of claim 1. As is known, the devices for closing road wells formed underneath road surfaces or open areas and intended for the most varied uses, for example for housing the valves and connection nozzles of tanks or cisterns, generally comprise a support frame stably fixed to the ground with cement mortar or other similar materials and defining an opening for access to the underlying cavity, and a plate-like element matching the edge of the said access opening so as to close it with its own weight. The plate-like element normally consists of a considerable mass of grey iron, for example of about 90 to 100 kg, in all those cases where the said plate-like element and the corresponding access opening are, for functional reasons, of large dimensions. In fact, the plate-like element must have a thickness suitable for withstanding, without undergoing substantial flexural deformations or being displaced from its seat, stresses and weights even of a significant nature, such as those imparted by vehicles which may pass on it. Opening a device for closing road wells of the type briefly described above involves carrying out a fairly difficult and physically tiring operation since two persons are required to exert simultaneously a raising force by means of suitable tools or special spanners which can be inserted into and rotated inside appropriate holes formed in the plate-like element. The latter, once it has been raised and separated from the support frame, is placed alongside the access opening. A similar operation must be performed when the plate-like element is to be rearranged in the closed position. It is obvious, therefore, that the cast-iron plate-like elements of the known type, in particular when frequent opening and closing operations must be performed, in addition to not being very practical to use owing to the necessary presence of two persons, also offer a limited degree of safety since the manual displacement of a metal mass of considerable weight may easily cause damage and injury to the workers involved. It has already been attempted to overcome the abovementioned drawbacks by constructing the plate-like elements using cast iron with improved mechanical strength characteristics, such as nodular cast iron, so as to be able to reduce their mass and hence the effort required for the opening and the closing operations. However, this known technical solution, in addition to involving in any case an operation which can be performed only by at least two persons, has proved not only to have a high cost owing to the improved qualities of the material used, but is also not entirely functional. In fact, these plate-like elements, since, for the same admissible load levels as those made of grey iron, have a limited thickness and hence an even considerably smaller mass, may be more easily deformed or dislodged from the seat inside which they rest only with their weight, owing to the repeated thrusting forces which are normally imparted to them by vehicles. It is also known from FR-A-2680811 a device for closing road wells comprising a rectangular frame defining an opening in correspondence of which a plate-like element is engaged.The plate-like element is hinged around a pivot axis and can be displaced from a closed position to an open position.Two springs are coaxially mounted on the pivot axis and present a first end portion directly acting and pushing against the plate-like element and a second end portion engaged with the rectangular frame. In this situation, the general object of the present invention is to devise a device for closing road wells in vehicle and pedestrian areas, which is able to overcome substantially the drawbacks mentioned. Within the scope of said general object it is an important object of the present invention to devise a closing device which can be simply and easily manoeuvred even by a single person and which allows one to perform, with a minimum amount of effort and in total safety, repeated opening and closing operations, including removal of the cover when this is required. The objects specified are substantially achieved by a device for closing road wells in vehicle and pedestrian areas according to the characterizing portion of claim 1. The description of a preferred embodiment of a closing device according to the invention is now provided by way of example and illustrated in the accompanying drawings in which: Fig. 1 shows a view, from above, of a frame forming part of the closing device according to the invention; Fig. 2 shows, in plan view, a plate-like element which can be coupled to the frame according to Fig. 1; Fig. 3 shows a section along the plane III-III according to Fig. 2; and Figs. 4, 5 and 6 show a cross-section of the closing device according to the invention in the completely closed, partially open and open position, respectively; Fig. 7 shows, in plan view, a constructional variant incorporating an element for adjusting the torsional pretensioning force of the spring associated with the plate-like closing element; Fig. 8 shows a longitudinally sectioned view of said adjusting element. Fig. 9 is a side view of the adjusting element according to Fig. 1. With reference to the figures mentioned, 1 denotes in its entirety a device for closing road wells in vehicle and pedestrian areas. It comprises a support frame 2, for example of substantially quadrangular shape, having an internal edge 3 defining an opening 4 for access to a well or to a cavity of any type. The support frame 2 has rotatably engaged with it a plate-like element 5 along a hinging axis 6. More precisely, the plate-like element 5 has peripherally, at the end of one side, a pair of lug-like projections comprising a first projection 7a and a second projection 7b engaging, respectively, with a first hinge pin 8 of smaller length and a second hinge pin 9 of greater length, said pins being aligned along the hinging axis 6. The first pin 8 comprises an active end zone 8a which can be inserted into a first housing recess 10a formed in the frame 2 and the second pin 9 comprises a first end attachment zone 9a which can be engaged with a second housing recess l0b provided in the frame 2 and aligned with the first recess 10a along the hinging axis 6. Moreover, the plate-like element 5 has at the bottom a perimetral shoulder 5a, which can be inserted into a correspondingly shaped cavity 2a of the frame 2 inside which a sealing gasket 11 consisting of compressible material is arranged. The perimetral shoulder 5a has, adjacent to it, an abutting edge 5b which can rest, in the closed position, against upwardly projecting support zones 2b of the frame 2. The perimetral shoulder 5a, correspondingly shaped cavity 2a and support zones 2b have suitable dimensions so that the sealing gasket 11 is adequately compressed when the abutting edge 5b is in contact with the support zones 2b. A torsional spring 12 is advantageously arranged between the plate-like element 5 and the support frame 2. The torsional spring 12 is of the helical type and comprises a first end portion 12a, inserted into a fastening seat 13 defined by a recess formed in the second projection 7b, and a second end portion 12b which is locked against the frame 2 via a stop element 14. The torsional spring 12 is arranged, wound onto an intermediate portion 9b of the second pin 9 extending in cantilever fashion away from the second projection 7b, and therefore has a working axis substantially coinciding with the hinging axis 6. Furthermore, the torsional spring 12 is designed and suitably arranged so as to be tensioned when the plate-like element is in the closed position (see Fig. 4) and slack when the said element is in the raised, i.e. open position (see Fig. 6). In the closed position the torsional spring 12 is arranged so as to exert a raising force at least slightly less than the weight of the plate-like element 5, so that the well remains per se closed. Moreover, for safety reasons, the plate-like element 5 is retained by means of one or two locking elements 15, for example of the bolt, bayonet or other type (Fig. 2). The second hinge pin 9 comprises, in addition to the intermediate zone 9b, a second free end zone 9c arranged in contact with an abutment block 16 integral with the support frame 2 and designed to withstand the flexural thrusting forces exerted on the second pin 9 by the torsional spring 12. With reference to Figures 7 to 9 and in accordance with a constructional variant of the invention, 17 denotes an element for adjusting the torsional pretensioning force of the torsional spring 12. This adjusting element consists substantially of a tubular body 18 which, prior to positioning of the plate-like element 5 onto the access opening 4 of the manhole cover, is fitted onto the second hinge pin 9. The tubular body 18 is provided with a seating 19 into which the first end portion 12a of the torsional spring 12 engages, the latter being then fitted onto the said second hinge pin 9. The second end portion 12b, however, is always intended to abut against the stop element 14. The tubular body 18 is moreover provided with at least one threaded transverse hole 20 inside which at least one locking screw 21 engages, the respective axis of which is shown in Fig. 7, for locking the said tubular body 18 on the second hinge pin 9. Once the tubular element 18 has been mounted with the torsional spring 12 on the second hinge pin 9, adjustment of the pretensioning force on the spring is obtained by rotating the tubular element and spring on the second hinge pin 9 so that the second end portion 12b is arranged at a predetermined angle with respect to the said second hinge pin 9. When the plate-like covering element 5 is inserted in the housing recesses 10a and 10b, owing to the action of the second end portion 12b against the stop element 14 of the torsional spring 12, the latter will assume a torsional pretensioning force proportional to the aforementioned angle. It must be noted that the position of the tubular body 18 on the second hinge pin could be inverted with respect to the torsional spring 12. In this case the spring would be wound in the opposite direction and would be mounted, rotated by 180° with respect to the configuration illustrated in Fig. 7, and the stop element 14 would be positioned close to the second projection 7b, while the abutment block 16 could be eliminated since the flexural movements of the second hinge pin 9 would be of a negligible amount. Operation of the device for closing road wells, which is described above from a mainly structural point of view, is as follows. In the closed position the plate-like element 5 keeps the abutting edge 5b in contact with the support zone 2b of the frame 2 owing to the action of the locking elements 15 opposing the twisting moment exerted by the torsional spring 12 with respect to the hinging axis 6 (see Fig.4). When it is required to open the well 1, it is sufficient to disengage the locking elements 15 and simply raise with one hand the plate-like element 5, exerting physically a force which gradually decreases as the cover is raised. When the equilibrium point is exceeded, for example at the angle of rotation of 60°, the torsional spring 12 automatically completes opening of the well (see Figs. 5 and 6). Similarly, during the closing operations, the plate-like element 5 is pushed towards the frame 2, opposing the increasing moment of the torsional spring 12 which is practically zero in the open position. When the closed position is approached, there is also an increase in the moment, with respect to the hinging axis, exerted by the weight of the plate-like element, obviously in a direction opposite to that of the torsional spring so that an operator is never required to exert a great deal of force, provided that the spring is properly calibrated. The invention achieves important advantages: First of all it is emphasized that the plate-like closing element of the well may be made of grey iron and may also have a large mass since the opening and closing action is performed mainly by a torsional spring and the force required of a person is in any case limited. The entire structure therefore has a low cost owing to the type of material which can be used for the construction thereof and offers all the mechanical strength and stability characteristics required in situations subject to high external stresses, also because the plate-like closing element is kept in position not only by its own weight but by the hinge pins and the elements locking it to the frame. Moreover, the opening and closing operations can be performed with a small amount of effort by a single operator and can therefore be easily repeated with great frequency. Finally, the device for closing road wells according to the invention allows one to operate in total safety, since the displacements of the plate-like element are guided by the hinging axis and the weight of the said plate-like element, even when considerable, does not constitute any danger since it is always counterbalanced by the action of the torsional spring. All the details may be replaced by technically equivalent elements and, in the practical realization of the invention, any materials and dimensions may be used according to requirements. In particular, the plate-like element may also have a shape different from that illustrated in the drawings, for example a round or rectangular shape, and the material used may be suitably reinforced sheet metal.

Claims: Device for closing road wells in vehicle and pedestrian areas, of the type comprising: a support frame (2) defining an opening (4) for access to a well; a plate-like element (5) for closing said access opening, said plate-like element being rotatably engaged with said support frame (2) about a hinging axis (6) so as to be movable between a raised open position and a lowered closed position, in which said plate-like element (5) perimetrally matches said frame (2); a torsional spring (12) having a working axis substantially coinciding with the hinging axis (6) and comprising a first end portion (12a) connected with said plate-like element (5) and a second end portion (12b) connected with said frame (2), said torsional spring (12) being arranged such that it is tensioned and exerts a raising force on said plate-like element when the latter is in said lowered closed position; said plate-like element (5) being engaged with at least one hinge pin (9) disposed along said hinging axis (6) and having an intermediate portion (9b)around which the spring (12) is wound, characterized by the fact that said first end portion (12a) does not directly push the bottom surface of the closure plate, and either said first end portion (12a) is engaged into a seating (19) provided on a tubular body (18) of a spring pretensioning adjusting element (17) locked on to said hinge pin (9), this latter being integral with the plate-like element (5), or said first end portion (12a) is fastened into a seat (13) formed in a peripheral projection of the plate-like element (5) disposed in correspondence of the hinging axis (6). Device according to Claim 1, in which said torsional spring (12) is a spring of the helical type. Device according to claim 2 in which said tubular body (18) is provided with at least one threaded transverse hole (20) for receiving a locking screw (21). Device according to Claim 2, in which said plate-like element (5) has integral with it two hinge pins (8, 9) located at a distance from one another and aligned along said hinging axis (6), said hinge pins (8, 9) comprising a first pin of smaller length (8) and a second pin of greater length (9) having said intermediate portion (9b). Device according to Claim 4, in which said plate-like element (5) has peripherally a pair of projections (7a, 7b) comprising a first projection (7a) and a second projection (7b) designed to engage with said first smaller pin (8) and said second larger pin (9), respectively, said second projection (7b) having formed in said seat (13) for fastening said first end portion (12a) of said helical spring. Device according to Claim 5, in which said second hinge pin (9) is engaged in cantilever fashion with said second projection of said plate-like element and comprises a first end attachment zone (9a) and a second free end zone (9c), said end zones comprising between them said intermediate portion (9b) around which said helical spring (12) is wound, and in which there is provided, integral with said support frame (2), an abutment block (16) for said second free end zone (9c) designed to withstand flexural thrusting forces generated on said second pin (9) by said helical spring (12). Device according to Claim 2, in which said helical spring (12), in the closed position of said plate-like element (5), exerts on the latter a force which is at least slightly less than the weight of the plate-like element (5) itself.

Inventors: LAMPERTI RICCARDO, LAMPERTI, RICCARDO
Applicants: LAMPERTI RICCARDO, LAMPERTI, RICCARDO
Application year: 1996
Main classification: E02D29
IPC codes: E05F1, E02D29