Patent application title: CONVERTIBLE DINING / BILLIARD TABLE
Jean-Claude Gras (Wiers, BE)
Curt Bossuyt (Escanaffles, BE)
SALUC TECHNOLOGIES S.A.
IPC8 Class: AA63D1504FI
Class name: Billiards or pool table or gameboard convertible to another type of furniture or to different type of game playing surface
Publication date: 2010-07-08
Patent application number: 20100173718
A convertible dining/billiard table includes features allowing a slim
design dining table at regular dining height, easily convertible in a
pool table. One feature is a pocket ball holder for a pool, snooker,
pyramid or other pocket billiard table, featuring a very flat design with
no depth when the pocket ball holder does not hold any ball, but able to
stretch and hold several balls when one or several balls are pocketed.
The ball holder includes an elastic membrane. The table is also provided
with a height adjustment mechanism, including two profiles, a first one
of the profile being slidably disposed inside a second one of the
profile. A third piece is provided consisting in a cylindrical bar moving
through specifically shaped cavities in the two profiles and engaging in
a first position when moving one profile in one direction.
17. A billiard table provided with means to convert the table into a dining table, said table showing no external features of a billiard table when set up as dining table, comprising a height adjustment mechanism placed in each leg of the table, said mechanism comprising two profiles and one cylindrical bar, a first one of the profile being slidably disposed inside a second one of the profile, and the cylindrical bar moving through specifically shaped cavities in the two profiles and engaging in a first position when moving one profile in one direction, the said cylindrical bar maintaining the moving profile to this first position when the said moving profile is moved in the opposite direction; the said cylindrical axis being removed and engaged in a second position when the moving profile is moved again in the first direction, the said cylindrical bar maintaining the moving profile to this second position when the said moving profile is moved back in the opposite direction.
18. A billiard table as claimed in claim 17 wherein the profile disposed inside the second one of the profile is the moving profile.
19. A billiard table as claimed in claim 17 wherein the profile disposed inside the second one of the profile is the fixed profile.
20. A billiard table as claimed in claim 17, wherein the pocket ball holders necessary to hold the balls when they are sunk while playing pool, snooker or the like, when the table is provided with such equipment, comprise a soft material which can be placed in such a way that, when it contains no balls, shows a very thin profile and therefore is not seen behind the table structure, even though the said structure is very slim.
21. A billiard table as claimed in claim 20, in which the pocket ball holders comprise an elastic membrane that can be stretched in a way that it may hold the desire number of balls, and come back to its original shape once the balls are released or removed.
22. A dining table as claimed in claim 21, wherein said elastic membrane is stretched between the edges of a wire frame.
23. A dining table as claimed in claim 22, wherein said membrane is stretched between the edges of a bi-dimensional wire frame.
24. A dining table as claimed in claim 21, wherein said membrane is constructed of a nylon stretchable cloth.
25. A dining table as claimed in claim 20, wherein said pocket ball holder is equipped with a flat thin plate horizontally slidable just above or below the said pocket ball holder when flat.
26. A dining table as claimed in claim 20, where a damping material is located between the pocket ball holder and the back of the billiard slate.
27. A dining table as claimed in claim 26, wherein the said damping material is a piece of a synthetic material foam fixed on the back of the slate.
28. A dining table as claimed in claim 17, where the pocket ball holder is within the table frame, being the apron or the legs, so that the balls can be stored without being seen from the outside.
BACKGROUND OF THE INVENTION
Billiard tables, including tables for playing pool, carom, snooker and other related games can be used as dining tables, by resting a cover or leave or top or panel over the table, but this solution gives different disadvantages. First the dining table formed by doing this is generally not at a convenient or comfortable height for dining, as the surface of such a dining table is normally too high due to the regular height of a billiard surface. The height difference is normally around 75 mm (3 inches). In addition, the space available for the legs, between the ground and the below surface of the table surface, is limited due to the large table apron necessary to hold the heavy slate plate used in regular billiard table as the playing surface (recovered by a cloth). Typically a slate used in a billiard table has a thickness of 3/4' (19 mm) or more, giving a weight over 90 kg for the playing surface on a 7' length playing surface, due to the density of the slate material used. On the other hand, the thick apron of a regular pool table allows to contain a ramp or rail system wherein the balls return to a storage rack or a specific area when they are pocketed. Instead of a rail or ramp system in the table apron, many tables have 6 pockets usually in leather or plastic to hold the balls once pocketed during the game.
BRIEF DESCRIPTION OF THE PRIOR ART
Mechanisms are known for adjusting the height of the surface of the table, thus allowing the table to used both as a pool table (or a billiard or snooker table) and as a dining table. When it is desired to convert the dining table to a pool table, the cover top across the cushions is released, and the height of the bed of the table is raised.
The following patent documents reflect the state of the art of which the applicant is aware:
U.S. Pat. No. 6,244,969; U.S. Pat. No. 6,102,808; U.S. Pat. No. 7,077,068; U.S. Pat. No. 6,997,116; U.S. Pat. No. 4,615,279; U.S. Pat. No. 6,095,463; U.S. Pat. No. 6,119,605; U.S. Pat. No. 6,055,912; U.S. Pat. No. 5,845,590, U.S. Pat. No. 5,758,586 U.S. Pat. No. 5,479,852; U.S. Pat. No. 4,156,391; U.S. Pat. No. 4,109,588; GB 0122273.6
Therefore, numerous prior height adjustment mechanisms exist. A lot of them are very complicated to manufacture, leading to a high cost. But more importantly, no one is able to guaranty a perfect lock in both positions, so that the transversal or horizontal stability is assured, which is very important for a pool table or a billiards or snooker table. All prior height adjustment mechanisms are indeed designed with a free motion between the different parts of the said mechanism to allow motion, and this transversal free motion or slack remain all the time, even when the moving part is at rest in one of its possible positions.
As an example, a prior art height adjusting mechanism, which has been known for many years, is shown in FIG. 14 and disclosed in GB 0122273.6 or US 2004/024033, herein incorporated by reference.
This prior art mechanism includes a first part 112, which is connected to the frame of the table, and a second part 130 which is connected to the bed. The parts are shown separated for clarity. As can be seen, the first part 112 comprises a generally flat member 114, which is normally formed from a metal such as brass. A number of grooves 116 are formed on a face of the flat member. The member is also formed with holes 118 for screws or the like, allowing it to be attached to a support frame of the table.
One problem with this prior art height adjusting mechanism 110 is that the peg 132 is moved in the slot 134 so that at all time and particularly when the said peg 132 is in the detent 120, the transversal or horizontal free motion necessary between the part 130 and the part 112 to let them move longitudinally remains and hence the horizontal stability is not assured.
All the other height mechanisms show the same stability problem since the free motion necessary to let the different parts moving each other is not locked while the moving part is on its possible positions. Furthermore, the other prior mechanism suitable for a pool table or the like are very complicated to manufacture, rising the cost drastically and increasing the possibility of jam, and hence reducing the reliability.
On the other hand, a pocket of a pool or snooker table comprises usually a piece in plastic or leather receiving the balls when they are pocketed.
Other pocket designs usually consist in a pocket liner as shown, beneath which there is either a ball holder or a ramp or rail system to return the balls to a storage rack or a specific area.
The prior art is reflected in the following patent documents:
U.S. Pat. No. 4,095,786; U.S. D349,742; U.S. D521,586; U.S. Pat. No. 5,451,187; U.S. Pat. No. 1,533,051; U.S. Pat. No. 1,535,926; GB190627414; UA19690U
All these systems have the disadvantage of needing an important vertical space and of being difficultly hide able in a reduced vertical space.
The design patent D521,586 proposes a rail system that can be movable in a horizontal position behind the table apron, but it remains partly visible and the mobile parts and mechanism lead to a high price and to vibration noise during the game.
SUMMARY OF THE INVENTION
The object of the invention is to provide a dining table, even possibly with a very slim cosmetic design, with a convenient and regular dining height and comfortable room space for the legs, convertible into a billiard table, even with an optimal height to play, without any visible billiard feature when set as a dining table. The present invention allows even to keep within the dining table all the billiard accessories, namely the cues, the ball rack, the chalk, the balls among other possible accessories, without the said accessories being visible or noticeable.
To achieve this, there is first provided a position adjustment mechanism placed in each leg of the table, the mechanism comprising: two profiles (sections), a first one of the profile being slidably disposed inside a second one of the profiles, and a third piece consisting in a cylindrical bar or peg moving through specifically shaped cavities in the two profiles and engaging in a first position when moving one profile in one direction, the said cylindrical bar maintaining the moving profile to this first position when the said moving profile is moved in the opposite direction, the said cylindrical bar being removed when the moving profile is moved again in the first direction and engaged in a second position when the said moving profile is moved back in the opposite direction, the said cylindrical bar maintaining the moving profile to this second position. The two positions of the said cylindrical bar allow the moving profile to be maintained in two different heights. Each said profile has its own specific cavity in each of two opposite lateral walls as shown in FIGS. 1 and 2, and the said cylindrical bar has a length at least equal to the external width of the external profile, the said width being measured from the wall with the cavity to the opposite wall with the cavity. Typically the moving profile is interdependent of the legs and the table, while the fixed profile is inside the moving profile and stands on the floor.
In another embodiment, the cavities (slots or grooves) of the profiles are designed such that, when the moving profile: pushes downwards or to the said opposite direction and is blocked at one of its height position, the longitudinal strength applied by the moving profile through the cylindrical bar transmits a transversal strength tending to push apart transversally the two said profiles, so that they are transversally blocked, each profile forcing transversally against the other profile, allowing a tight fit and increasing the stability.
The preferred material used for the three parts is steel or aluminium, although other metals or hard synthetic material might be used.
In another embodiment the said cylindrical bar is connected to the said fixed profile with one or more springs in tension, so that said cylindrical bar is forced to move longitudinally towards its possible positions. Although this is not necessary when the mechanism of the present invention is used vertically because the said cylindrical bar tends to go downwards due to its own weight, the said springs allow to use the mechanism in all positions for all kinds of possible distance adjustments such as horizontally or upside down.
In another embodiment, the two said profiles are linked by a resilient means such as a spring or a pneumatic or hydraulic jack that tend to keep the said profiles away. This is to compensate the weight of the piece of which the height must be positioned, such as a billiard or pool or snooker table. The strength of the resilient means is always lower than the weight to move, the difference between the resilient strength and the weight being the necessary force to apply to put apart the profiles and make the mechanism work.
Preferably, one of the profiles is in contact with a first body and the other of the profiles is in contact with a second body, with motion of the profiles between the first position and the second position serving to adjust the distance between the bodies.
To lift the table in its billiard height, one simply needs to lift by hand one short side of the table until the first click, and then do it again with the other table side.
To achieve the object of the invention there is also provided a pocket ball holder that shows a low vertical dimension when it does not hold any ball, such as it can easily be placed in a slim table structure without seeing it, even from a perfectly horizontal perspective, and that can stretch to be able to hold several balls when they are pocketed.
This is particularly interesting to hide the pocket into a slim table design when the table is converted in a dinning table that look as a real dining table. Indeed, dining tables do not usually have a thick apron which would be a problem to have enough place for the legs, and which would not be aesthetic. Thanks to the present invention, any dinning table design, even with an apron as low as 3 inches, may contain in this thickness the billiard cushions, the billiard slate and the pockets without being seen from the side of the table.
The said ball holder may be of various horizontal dimensions and various tensions and elasticity of the membrane to allow to hold the desired number of balls.
A further object is to provide a combined mechanism that may be used to keep the balls in the pockets, without letting them stretching the pocket holder, so that the balls remain entirely invisible when laying in the pockets, once the table top is put on the table to convert the latter into a dining table.
This invention allows also to provide a billiard table pocket ball holder which is simple in design, inexpensive to manufacture and durable.
These objects, as well as further objects and advantages, of the present invention will become readily apparent after reading the description of a non-limiting illustrative embodiment and the accompanying drawings.
According to the main features of the second object of the present invention, a pool table pocket ball holder that shows a very thin vertical dimension includes an elastic membrane stretched below the game pocket holes in such a way that several balls may drop and lie in the pocket. Once the balls are removed, the pocket ball holder recovers its flatness. The membrane may be stretched between the edges of a rectangular or differently shaped wire frame.
In addition, according to an embodiment, the above system may also include any type of movable plate or wire element able to slide just above or below the membrane, preventing the balls to stretch the membrane so that the balls keep at rest above the pocket ball holder when no play occurs, hided behind the table apron. This allows to keep all the billiard accessories in the dining table, between the playing surface and the table top except the balls that rest in the pockets with the movable plate placed just against the membrane, without being seen from the outside, everything being kept in the space available in the table apron height, as low as 3 inches thick. The said plate slides easily aside when it comes to play, to have the membrane free to stretch to receive one or multiple balls.
BRIEF DESCRIPTION OF THE FIGURES
In order that the present invention may be more fully understood it will now be described, by way of non limitative examples, with reference to the accompanying drawings in which:
FIG. 1 is a schematic perspective view of a traditional pool table
FIG. 2 is a schematic perspective view of a slim design dining table that may hide a regular pool table according to this invention
FIG. 1 is a schematic perspective view of the moving profile of the height adjustment mechanism.
FIG. 2 is a schematic perspective view of the fixed profile and the cylindrical bar of the height adjustment mechanism.
FIG. 3 is a side cut view of the moving profile of the height adjustment mechanism.
FIG. 4 is a side cut view of the cylindrical bar of the height adjustment mechanism.
FIG. 5 is a side cut view of the fixed profile of the height adjustment mechanism.
FIG. 6 is a side cut view of the height adjustment mechanism at its lower position
FIG. 7 is a side cut view of the height adjustment mechanism at its upper position
FIG. 8 is a side cut view of the height adjustment mechanism while the moving part is moved upwards to unlock the said moving profile from its upper position
FIG. 9 is a side cut view of the height adjustment mechanism either during the downwards move of the moving profile towards its lower position or during the upwards move of the moving profile from its lower position.
FIG. 10 is a side cut view of the height adjustment mechanism showing the distribution of the forces transmitted by the moving profile to the fixed profile
FIG. 11 is a side cut view of the preferred embodiment of the height adjustment mechanism included in one billiard or pool or snooker table leg.
FIG. 12 is a schematic view of the mechanism with the use of an excentric pulley
FIG. 13 is a front cut view of the mechanism, showing the possibility of maintaining the cylindrical bar with springs.
FIG. 14 is a view of a prior art mechanism.
FIG. 15 is a perspective view of an existing pocket.
FIG. 16 is a perspective view of another existing pocket
FIG. 17 is a perspective view of an existing pocket liner.
FIG. 18 is a view of a metal frame that can be used for the present invention
FIG. 19 is partial view of the preferred pocket ball holder
FIG. 20 is a side view of the pocket ball holder
FIG. 21 is a side view of the pocket ball holder with balls
FIG. 22 is a perspective view of the bottom of the corner of a pocket billiard table mounted with the pocket ball holder
FIG. 23 is a perspective view of the sliding mechanism
FIG. 24 is a side view of the corner of a sleek pocket billiard table mounted with the pocket ball holder
The preferred embodiment of this invention is a combination of a dining table, even with a sleek design, that can be converted into a pocket billiard table such as a pool or a snooker table, and pocket ball holders placed in the billiard table frame in such a way that the pocket ball holder are thin and not visible from the outside when not operative. The table frame or apron 31 as seen in FIG. 24 may be as thin as 31/4'' or 8.25 cm and contain as seen in FIG. 26 the cushion 235 of a typical height of 13/4'' or 44 mm, the 3/4'' or 19 mm slate 234, the support 233 of the slate that may be a 5 mm thick steel corner fixed to the apron 231, the 5 mm synthetic foam fixed on the below surface of the slate, near the pockets, the pocket ball holder 220 of typically 1/8'' or 3 mm, the sliding plate mechanism 240 and 241 with a thickness of about 4 mm fixed on the support 233, the small metal pieces 232 fixing the pocket ball holder 220 on the support 233 and adding a thickness of 2 mm. The total thickness of all the elements is 77 mm which is well smaller than the thickness of frame or apron.
FIG. 20 shows an example of wire frame that can be used for the pocket ball holder. Other shapes may be used and may be different for the four corner pockets and for the two side pockets. The side has a dimension typically between 20 and 35 cm, and the wire used is typically in steel with a diameter typically between 2 and 7 mm, although other type of wires or profiles may be used. The profile of the wire frame is flat to be as thin as possible as seen in FIG. 22, although different shapes might be used to better fit with the geometry of the table or to have fixings integrated to the said frame.
FIG. 21 shows the elastic membrane 221 slightly stretched around the wire frame. The elastic membrane may be a stretchable nylon cloth for example. The said membrane is fixed on the wire frame by sewing or gluing the membrane edge around the wire, or with small pins on the wire frame that catch the membrane, or with another frame of the same shape fixed on the complementary wire frame, or by any other means.
When the membrane is at rest, without holding any ball, the pocket billiard holder 220 is flat, as seen in FIG. 22. When balls are pocketed, the membrane 221 is stretched and allows to hold a number of balls, between 1 and 6, just like a regular leather or plastic pocket. Once the balls are released or removed, the membrane recovers its original flat shape, as shown in FIG. 22.
In another embodiment, the pocket ball holder is combined with a damping piece such as a synthetic foam of 2 to 10 mm typically, said damping piece being fixed by glue or by a double sided tape on the rear/below side of the slate near or around the hole, such that if balls are bouncing when they are pocketed due to the elastic membrane, the said balls don't hit the rear part of the slate but are damped instead.
In still another embodiment, a sliding mechanism as shown in FIG. 25 is combined with the pocket ball holder, to allow to place balls in the holes without stretching the pocket ball holder. This is useful to have the balls available in the table when it is in the dining configuration. There is indeed not enough room between the slate and the table top to keep the balls. By sliding the sliding plate 241 in its profile 240 that is fixed on the steel corner 233, the balls can be placed in the holes without stretching the pocket ball holder, so that they remain in the thickness of the table apron, like the ball 236 shown in the FIG. 26. Due to the regular or standard size of the holes, three balls can be stored in such a way within the corner pockets, and two in each side pocket, so that the 16 balls of a pool set can be stored that way and be available in the table. The other accessories such as the cues, the ball rack, the chalk, the brush can be stored between the slate and the table top. The sliding plate 241 may be a thin metallic or plastic plate, and the holding profile 240 in which the sliding plate 241 moves may be in plastic or in metal for instance.
In another embodiment, the balls may be stored in the legs of the table.
According to another aspect of the present invention, which may be implemented independently of the above discussed features, it is provided the possibility of having a height adjustment mechanism placed in each leg of a convertible dining pool table so that one may lift the table about 3 inches to optimize billiard play.
As seen in FIGS. 3-11, the height adjustment mechanism of the present invention comprises three main parts, a fixed profile 14, slidably disposed into a moving profile 10, and a cylindrical bar 13 going through specifically shaped cavities 11 of the moving profile 10 and also through the specifically shaped cavities 12 of the fixed profile 14. In another embodiment, the moving profile 10 with its specifically shaped cavities 11 may perfectly be smaller and slidably disposed into the fixed profile 14 with its specifically shaped cavities 12. The said cylindrical bar has a length at least of the external width of the external profile, the said width being from wall with the cavity to the opposite wall with the cavity, and the longitudinal position of said cylindrical bar may be maintained by 2 small pins or o-rings just inside the inner profile.
In the preferred embodiment, the moving profile 10 is in contact with a first body such as the bed of a pool or billiard or snooker table, while the fixed profile 14 is in contact with a second body such as the floor, and in case of a pool or billiard or snooker table to which the height must be adjusted to transform the said table to a dinning table and vice versa, the mechanism of the present invention may be located in each leg of the table.
In its lower position as in FIG. 8, the moving profile 10 is maintained at the end 50 of its cavity 11 by the cylindrical bar 13, the said cylindrical bar 13 being maintained by the edge 60 of the cavity 12 pertaining to the fixed profile 14. When the moving profile 10 is moved upwards as shown in FIG. 11, the cylindrical bar 13 stays roughly in the same area of the cavity 12, because the said cylindrical bar is maintained by the edge 51 of the cavity 11, until the area 52 of the cavity 11 allows the said cylindrical bar 13 to go by gravity or pulled by its springs 100 to the detent 61 of the cavity 12.
When the moving profile is then released, it is maintained at its upper position by the edge 53 of its cavity 11, maintained by the cylindrical bar 13, the said cylindrical bar 13 being maintained by the edge 62 of the cavity 12 pertaining to the fixed profile 14.
To come back to the lower position, the moving profile 10 is moved upwards, and the cylindrical bar 13 is then rolling or sliding along the edge 54 of the cavity 11, up to the corner 55 of the cavity 11, at which position the moving profile 10 can not be move upwards further, as shown in FIG. 8.
When the moving profile 10 is then released, the cylindrical bar 13 is first staying in the detent 63 of the cavity 12, until the edge 56 of the cavity 11 forces the said cylindrical bar 13 to quit its position and roll or slide on the edge 60 of the cavity 12 and be stopped by the edge 51 of the cavity 11, as shown in FIG. 11. The profile of the edge 56 of the cavity 11 is important to assure that the cylindrical bar 13 moves off its position from the detent 63 of the cavity 12 easily, and that the said cylindrical bar 13 goes on the edge 60 of the cavity 12 only once the edge 53 of the cavity 11 is below the said cylindrical bar 13.
When the moving profile 10 is completely released, it is at its lower position as shown in FIG. 8.
In another embodiment, the profile of both cavities 11 and 12 is such that at its upper and lower position, the mechanism of the present invention is locked, and stable without any slack horizontally. During the movement of the present mechanism, as shown in FIG. 11, a free motion or slack 80 is necessary to let the inside profile sliding easily. When the mechanism is at its lower or upper position as shown in FIG. 12, the force F1, corresponding to the weight of the body such as a pool table applied on the mechanism minus the strength of the resilient means if any, is transferred through the cylindrical bar 13 to the fixed profile 14, the contact point between the said cylindrical bar 13 and the fixed profile 14 being on the edge 62 of the cavity 12 pertaining to the fixed profile 14. Due to the angle of said edge 62, the resulting force F2, normal to the said edge 62, may be decomposed in one horizontal force F3 and in one vertical force F4. The said force F4 being of the same intensity as the applied force F1, the horizontal force F3 depends on the angle of the said edge 62. More the angle is high, tending the edge to the vertical, more the horizontal force is high. The preferred value for the angle of the edge 62 is anywhere between 40° and 70°. The reacting force of the force F3 applied on the fixed profile 14 is the force F5, applied on the moving profile 10 through the cylindrical bar 13. These horizontal forces F3 and F5 force both profiles against each other at the contact surface 81, annihilating the free motion and blocking with a high horizontal stability the two profiles. This is particularly useful when the body fixed to the moving profile is a pool table because it is important to have no free motion or horizontal slack.
As shown in FIG. 13, the preferred embodiment of the height adjustment mechanism comprises a fixed profile 14 standing on the floor through the piece 75, and a moving profile 10 connected to the bed of a pool or billiard or snooker table through a leg 70. In the preferred embodiment of the present invention, four mechanism are disposed each in one such leg 70, and the height adjustment mechanism allows to position such a table either in the upper pool position or in the lower dinning position, the distance between both position being typically three inches or 7.6 cm. In its dining position, the table is covered by tops resting on the cushions.
In another embodiment of the invention, a resilient means such as the spring 71 is pushing or pulling as shown in the FIG. 13 the moving profile upwards. This is to compensate the weight of the pool table and help the user to adjust the height with few effort. The tension delivered by the spring or the resilient means is always lower than the weight that the mechanism must adjust, the difference between the weight to adjust and the strength of the resilient means being the necessary force to move the mechanism and make it work. In the example shown in FIG. 13, the spring is in tension and fixed on its upper end to the fixed profile 14 through an bar 72 and on its lower end to the moving profile 10 through an bar 73. The moving profile being in this example outside the fixed profile, a cavity 74 in the fixed profile 14 is performed, to allow the bar 73 pertaining to the moving profile 10 to move.
In still another embodiment of this invention as shown in FIG. 14, the spring 71 or the resilient means is attached to the moving profile 10 with a cable 79 through an excentric pulley 77, the geometric center of the said pulley 77 being C1 and the bar 76 around which the pulley 77 can turn is attached to the fixed of the profiles. The cable is fixed on the pulley such that it doesn't slide on the said pulley 77. The excentricity between the geometric center C1 of the pulley 77 and the rotation bar 76 of the pulley 77 is noted d, and the radius of the pulley 77 is noted R. The position of the pulley 77 when the moving part 10 is at its lower position is with the geometric center C1 of the pulley vertically over the pulley bar 76. The position of the pulley 77 at the upper position of the moving profile 10 is when the center of geometry C2 of the pulley is horizontally to the right of the pulley bar 76. The pulley 78 is actually the position of the pulley 77 once the moving profile 10 is at its upper position. With the right choice of the said excentricity d and the radius R of the said pulley 77, it is possible to keep almost constant the force necessary to move upwards the moving profile 10, and have the same force at the end of the move than initially. Indeed if F is the force transmitted by the spring through the pulley 77 and the cable 79 to help to move the moving profile upwards and if F1 is the initial force given by the spring 71, the force of the spring applied on the moving profile during the move is given by the formula
F=(F1-kx).(R+d. sin(x/R))/(R-d. sin(x/R))
where x is the downwards distance made by the end of the spring 71 attached to the cable 79, and k is the constant of the spring 71.
The force of the spring 71 is decreased by the value k.x as the moving profile 10 moves upwards. This diminution is however compensated by the excentricity of the pulley 77 due to the creation of an increasing lever arm in the right side of the pulley in the FIG. 14 while the moving profile 10 goes upwards. The excentricity correction is given by the factor (R+d. sin(x/R))/(R-d. sin(x/R)), always greater than 1 for x/R varying from zero to PI/2 or 90°.
To have F=F1 when the moving profile 10 is at its higher position, which is when x/R equals PI/2 or 90, the above formula becomes R/d=2.F/(k.x)-1. We also know the moving profile has moved upwards a distance of PI/2.R-d, and x=PI/2.R+d.
If F=40 kg, k=1 kg/cm, D=10 cm, we find after resolving a second degree equation d=1.3717 cm and R=7.2394 cm. This means that if the table weigh 200 kg, and the spring in each leg as a force of 40 kg, the force necessary to position the table to the upper position is 20 kg per each of the two table sides, and when the table is at its upper position, the force necessary to move upwards again the table to release it afterwards to its lower position is still 20 kg per side when an excentric pulley as described above is used. Without the excentric pulley, with the same values cited in this example, the force necessary to move upwards the table is 30 kg per side.
In another embodiment of the present invention as shown in FIG. 15, the cylindrical bar may be maintained and pulled downwards by two springs 99 through a facultative piece 98, the said springs being fixed on an bar 97 pertaining to the fixed profile 14. This allows the mechanism of the present invention to work in all possible positions. In the preferred vertical position, these springs 99 ensure that the cylindrical bar 13 will never be positioned other than perpendicularly to the cavities 10 and 12. It also guarantee that the said cylindrical bar 13 will remain in place during the transportation of the mechanism.
Patent applications in all subclasses Convertible to another type of furniture or to different type of game playing surface