FR2484498A1 - Automatic centring and locking inspection manhole cover - has rounded spigot ends on closure engaging ramps on cover to prevent rocking - Google Patents

Abstract

The cover is suitable for carriageways and has a frame (1) with a central circular opening and three 120 degree housings, each housing having an engagement ramp and seat and a counter slope and lock slope. The circular removable closing cover (2) has three peripheral spigots (3) at 120 degree spacing engaged in the housing during use. The spigots have a front beak (3d) with a lead edge that is rounded horizontally forming a circular or spheroid segment, which comes up against the counter slope of the frame housing locking the cover in position.

Description

Manhole cover self-closing, self-centering and locking.

The present invention relates to a self-closing buffer manhole, with automatic centering and locking, more specifically intended for pavement equipment and comprising a frame installed at the upper part of the chimney made in the ground and a removable closing buffer.

In order to obtain a self-closing of the tampon, it is known (French patent NO 72/06377) to equip the latter with three peripheral studs spaces of 1209 and intended to cooperate with indentations made in the fixed frame, at the edge of its circular opening, said studs and notches having complementary ramps promoting their relative sliding ensuring a downward rotation of said pad.

According to such an embodiment, a self-closing and a self-locking of the pad are obtained, the positioning of which takes place under the effect of its own weight, after the studs have been engaged in the upper part of the notches.

However, this advantageous embodiment did not make it possible to solve the problem of the perfect seating of the tampon on the frame which we tried to solve in different ways with more or less conclusive results.

In fact, according to the various solutions proposed, all of the flat surfaces of the slopes and counter-slopes of the tenons and the notches or housings are never in perfect contact, given the foundry sheet metal. This results in instability of the elements of the gaze. under the effect of racket "resulting from the rolling loads circulating on the roadway, this instability being progressively aggravated by the wear of the surfaces in contact. On the other hand, due to the flatness of the surfaces called upon to come into contact at the end of the downstroke. of the buffer, when the three studs or lugs are locked, there is not a rotation of said buffer which is essential for said lugs to take their final place together, but an anarchic tilting of the latter, leading to results of very imperfect locking and stability contacts.

An object of the present invention is to remedy these drawbacks.

This object is achieved by means of an embodiment according to which the peripheral lugs or lugs with which the pad is provided comprise a front spout, the end of which is intended to come into abutment against the locking counter-slope of the additional housings arranged in the frame, has a rounded horizontal support surface.

According to a particularly advantageous embodiment, the bearing end of the front spout of the tenons is constituted by a spherical or spheroidal segment.

According to an alternative embodiment, the bearing end of the front spout of the tenons has a frustoconical shape.

According to another characteristic, the front spout of each tenon or lug comprises an upper retaining ramp leading above its rounded support end, while each housing is provided with an upper retaining slope and a lower counter-slope for locking different obliquities.

Thanks to the aforementioned arrangements, a perfect articulation is created at the three support points, making it possible to obtain, in complete safety, a locked stabilization of the pad in the frame, based on six permanent contact points.

Another advantage of the invention stems from the fact that, taking into account the rounded, spherical or frustoconical conformation, of the bearing surface of the forelegs of the tenons or lugs of the tampon, each wear of the surfaces present is immediately compensated for by a tiny rotation of the pad on its supports, which allows to maintain, in full, the efficiency of centering, locking and stability.

On the other hand, the second counter-slope of the housings of the frame forms an advanced covering of the pins or lugs of the tampon engaged in said housings, which constitutes additional security against any risk of accidental extraction of said tampon, for example during passage of vehicles on a particularly used assembly.

These aims, characteristics and advantages, and others still, will emerge more clearly from the description which follows and from the appended drawings in which
Figure 1 is a plan view of the manhole according to the invention executed in a first embodiment very interesting and whose removable pad is shown locked in the service position in the fixed frame.

FIG. 2 is a detail view and in plan, to a larger one, illustrating the positioning of a lug of the tampon in a housing of the frame, according to the very advantageous embodiment represented in FIG. 1.

Figure 3 is a sectional view along line 3 - 3 of Figure 2.

Figure 4 is a detail and plan view, similar to Figure 2 and showing the positioning of a lug of the pad in a housing of the frame, according to another embodiment of said lug.

FIG. 5 is a sectional view along line 5 - 5 in FIG. 4.

Figure 6 is a schematic view for explaining the behavior of the pad on its frame under the effect of radial forces.

Reference is made to said drawings to describe an advantageous, although not limiting, embodiment of the look for pavements according to the invention.

According to the particularly advantageous embodiment illustrated in FIGS. 1 to 3, the manhole comprises, in a known manner, a frame 1 provided with a circular central opening and intended to be installed, in a manner adjustable in height or not, around the opening. upper dSune access chimney formed in the ground, and a removable closing pad 2, of circular shape. The latter is provided with three pins or peripheral lugs 3 spaces of 1200, engaging, in the service position, in three housings 4 also spaced by 1200 and housings in the internal border of the frame, said tenons and housings being arranged radially following an equilateral triangle.

Each of the housings 4 of the frame 1 comprises an engagement and dtassise-4a ramp having, for example, a slope of 300 relative to 1 2horizontal.

Opposite said engagement and seat ramp, each housing comprises, according to a characteristic of the invention, an upper counter-slope 4b forming retaining projection, and a lower counter-slope of abutment and locking 4c which , According to the mode-diexecution represents, has, horizontally, an arrangement perpendicular to the horizontal longitudinal axis x - x of said housing.

The inclination of the abutment and locking counter-slope 4c, with respect to the horizontal, is clearly greater than that of the retaining counter-slope 4b. The lower counter-slope 4c has, for example, an inclination of the order of 75 "with respect to the horizontal, while the upper counter-slope 4b has, for example, an obliquity of 36 with respect to the horizontal.

According to an important characteristic of the invention, each of the tenons or lugs 3 of the pad 2 has a 3d front spout oriented in the direction of the downward direction of rotation of said pad and the end of which intended to abut against the counter-slope locking housing 4c, has a rounded horizontal support surface.

In a particularly advantageous manner, the bearing end 3c of the 3d avantbec of the tenons 3, has the shape of a spherical segment or of a spheroldal segment. In this way, when the pad 2 is in the service position, each tenon or lug 3 is in point contact, by the spherical or spheroidal end 3c of its 3d front spout, against the abutment and locking counter-slope -4c of associated housing 4.

On the other hand, each of the tenons or lugs of the buffer comprises an engagement and seat counter-slope 3a having an obliquity equal to that of the engagement and seat ramp of the housings of the frame, that is, for example, a obliquity of 300 with respect to the horizontal.-Each tenon or lug still has, opposite the counter-slope 3a, an upper retaining ramp-3b ending above its support end 3c in the form of spherical segment or other rounded surface.

The obliquity of the retaining ramp 3b is slightly greater than that of the counter-slope 4b of the advance of said housings.

Thus, the retaining ramp 3b has, for example, an obliquity of 40 relative to the horizontal.

There is shown in Figures 4 and 5, an alternative embodiment according to which the support end 3c ′ of the 3d front beaks of the tenons or lugs 3 has a frustoconical shape.

According to this embodiment, each tenon or lug bears, when the pad 2 is in the service position, against the locking counter-slope 4c of the associated housing, by a generator of the frustoconical end of its 3d nosepiece , which forms a locking ramp 3c. The inclination of this locking ramp, relative to the horizontal, is equal to that of the locking counter-slope 4c of the housings 4 of the frame 1.

On the other hand, and as can be deduced from the above, the slope of the locking ramp 3c ", with respect to 1Shorizonta7e, is clearly greater than the lsobliqu7te of the retaining ramp 3b of the studs or lugs.

It is well understood the mode of operation of the means described above.

The pad 2 being placed on the frame I and the tenons or lugs 3 placed in line with the entrances to the housings 4, a slight rotational movement is imparted to said pad, the said lugs of which engage on the loading and seating ramps 4a said housings. The rotation of the buffer continuing, the tenons or lugs continue their descent on the ramps 4a, the parallel surfaces of the counter-slopes 3a and of said ramps sliding one over the other. Due to the differences in the gross foundry dimensions of the contact surfaces, this slip does not have the same value for each of the three "tenon-housing" assemblies. However ~ at no time does the pad limp and the sliding continues until, successively, the locking surfaces 3c - 4c, or 3c '' - 4c, of all said assemblies have come into contact.

It is observed that the coming into contact of the locking surfaces of the three "tenon-housing" assemblies practically never takes place simultaneously.

Virtually, in fact, a contact is made with the locking surfaces 3c - 4c, or 3c "- 4c, with a first, then with a second set" tenon-housing11, then by rotation and sliding of the spherical ends or spheroidal 3c, or locking ramps-3c ", on the counter-slopes 4c of said first and second sets, under the effect of the descent which continues at the level of the third stud or lug, the buffer takes its final stable position by bringing the spherical or spheroidal end, or the locking ramp, of said third stud or lug into contact with the locking counter-slope of the associated housing. It can then be seen that, vertically, the pad rests on three points (support against slopes 3a of the three lugs on the ramps 4a of the three associated housings) and quril is maintained in the centering and locking position by another support at three points (spherical or spheroidal ends 3c, or ramps 3c, of the three lugs on the 4c counter-slopes of the three dwellings); this centering and this perfect locking resulting in particular from the spherical or frustoconical shape of the support ends of the front spouts of the tenons which form as many pivot points promoting the perfect positioning of said buffer and ensuring the permanence of this perfect positioning despite the sheet metal possible manufacturing or usurpation of the contacting surfaces.

It is understood that the three tenons or lugs are self-centering, at the time of installation, by the play of the descents on the support ramps of the buffer and by the stops of the front spouts on the locking counter-slopes. Each tenon or lug is held in the support position on three points, due to the reactions of which it is the subject: -10) on the part of the other two tenons or lugs; - 20) from the engagement and seat ramps that it is unable to ascend.

Reference is made to the diagram in FIG. 6 to describe the behavior of the buffer under the effect of radial forces.

1) impulse to move the buffer radially inwards.

If we consider for example, the application of a force tending to move the pin C in the direction of a3 -c3, we see that such a movement is im possible given the fact that the pin A is supported on b1 - -c which has the same orientation as a3-c3, and that B cannot move towards ba, due to the inclination of the engagement and seat ramp on which it rests.

This is the case for each of the support points A, B, C for which any radial movement towards the interior is prohibited.

20) inclination to move the buffer radially outwards.

If we suppose, for example, the application of a force tending to move the tenon C in the direction of a3-b3, considering the blocking that creates the support of the tenon B on 2 3 having an orientation identical to a -b, for a movement to occur, the tenon A must go back up on its fixed ramp, in the direction of a1-b1. However, this movement is prohibited by the very presence of the disturbing load which tends, on the contrary, to apply, downwards, the tenons A, B, C.

 the same applies to each of the support points A, B, C for which any radial displacement, inward or outward, is therefore prohibited.

Finally, it is useless to demonstrate the obvious impossibilities of moving A, B, C: - in the direction of a, as this would suppose an impossible rise of the lugs or lugs of the pad on the engagement and seat ramps; - in the direction of cbb, because A, B, C are in abutment on ~ -bD by means of the locking lugs.

We could multiply the examples and combinations without it being possible to modify the advantageous results obtained. It can therefore be concluded that there is only one possible position, for a buffer locked in its frame, and that this position does not vary regardless of the stresses to which said buffer is subjected. This position is located along the straight lines a-b, therefore at the bottom of the engagement and seat ramps, and more or less to the right or left of their center according to the degree of control of the manufacturing dimensions. Once fixed, these points no longer vary and the buffer is auto = center permanently.

Claims (11)

1. - Manhole cover self-closing with automatic centering and locking, more specifically intended for fitting footwear and comprising - on the one hand, a frame (1) provided with a circular central opening and three housings (4 ) spaces of 1200 and households in the internal border of said frame, each of said housings comprising an engagement ramp ~ and seat (4a) and a counter-slope of abutment and locking (4c); and, on the other hand, a removable closure pad (2), of circular shape, provided with three peripheral pins or lugs (3) also spaced 1200 apart and intended to be engaged, in the service position, in said housings, characterized in that said tenons or lugs have a front (3d) whose end intended to abut against the locking counter-slope (4c) of said housings, has a rounded horizontal support surface (3c, 3c ') . * 2. - Manhole according to claim 1, characterized in that the bearing end (3c) of the front spout (3d) of the tenons or lugs (3) has the shape of a spherical segment or a spheroidal segment. 3. - Manhole according to claim 1, characterized in that the bearing end (3cl) of the front spout (3d) of the tenons or lugs (3) has a frustoconical shape. 4. - Manhole according to claim 2, characterized in that each tenon or lug (3) is placed in point support, by the spherical or spheroidal end (3c) of its front spout (3d) forming a locking point, against the abutment and locking counter-slope (4c) of the associated housing (4), when the pad (2) is in the service position on the frame (1). 5. - Manhole according to one of claims 1 or 3, characterized in that the front spouts (3d) of the pins or lugs (3) bear on the locking counter-slopes (4c) of the housings (4) by the through a generator, forming a locking ramp (3c "), with their rounded end. 6. - Manhole according to any one of claims 1 to 5, characterized in that the front spout (3d) of each tenon or lug (3) has an upper retaining ramp (3b) terminating above its extremity d 'rounded support (3c, 3Cl) 9 while each housing (4) is provided with an upper retaining slope (4b) and a lower locking counter-slope (4c) of different obliquities. 7. - Manhole according to claim 6, characterized in that the inclination of the counter-slope (4c) for locking, relative to the horizontal, is much more pronounced than that of the counter-slope (4b) for retaining housings (4). 8. - Manhole according to claims 5 and 7, characterized in that the inclination of the locking ramp (3c "), relative to the horizontal, is much more pronounced than that of the retaining ramp (3b) studs (3). 9 ..- Manhole according to any one of claims 5 to 8 characterized in that the locking ramp (3c) and the locking counter-slope (4c) of the pins (3) and of the housings (4), respectively, have an identical obliquity. 10. - Manhole according to any one of claims 6 to 9, characterized in that the inclination of the retaining ramp (3b) of the pins or lugs, relative to the horizontal, is slightly greater than the obliquity of the retaining counter-slope (4b) of the accommodation. 11. - Manhole according to any one of claims 1 to 10, characterized in that the locking counter-slope (4c) of each of the housings has, horizontally, an arrangement perpendicular to the longitudinal axis (x - x) of said housings. 12. - Manhole according to any one of claims 6 to 11, characterized in that the retaining ramp (3b) of the lugs or tenons (3) has, relative to the horizontal, an inclination of 40, and in that that the retaining counter-slope 14b) of the housings (4) has, with respect to the horizontal, an obliquity of 36.