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AssigneeCompagnie Francaise d'Enterprises Metalliques
InventorGilbert Laplante
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The invention provides a propulsive-force jack installation for producing the continuous movement of an oblong object (1) in the direction of its axis and it is characterized in that it comprises two jack assemblies whose pistons (6, 6') work in seesaw fashion, a piston (6) of one assembly taking in charge said object (1) as soon as the piston (6') of the other assembly ceases this action, offload movement of the piston (6 or 6') and its locking on the object (1) being controlled automatically just before the arrival at the end of travel under load of the other piston (6' or 6) and the offload descent of one piston (6 or 6') being controlled automatically at a time which follows the beginning of the taking in charge of the object by the other piston (6' or 6). The invention may be applied to hoisting, self-raising, prospection, or working platforms at sea.
A propulsive-force jack apparatus for producing continuous movement of an oblong object in an axial direction and/or of an element along a said oblong object, said apparatus comprising at least two jack assemblies, each of which comprises a piston slidably movable in a corresponding jack body, locking means associated with the piston of each assembly for interlocking the pistons selectively, momentarily and automatically with the object, a device for supplying hydraulic fluid to said jack assemblies, and an automatic control means for controlling said locking means and for controlling supplying of said hydraulic fluid to, and the discharging of said hydraulic fluid from, said jack bodies such that engagement of said object by a said piston of one of said jack assemblies is effected in a continuous manner at the moment when the said piston of the other jack assembly is disengaged from said object and such that the relative movement of the piston of one assembly with respect to the piston of the other assembly is a synchronous seesaw movement, the offload movement of the piston of each of the jack assemblies being faster than the movement under load, effected in the opposite direction, of the piston of the other jack assembly, wherein each movement, under load, of said piston of each jack assembly is preceded by a short off-load movement of the same piston in the same direction, said automatic control means comprising, for each jack assembly, a first sensor for detecting the arrival of the respective piston of the corresponding body at a position (N2, N2') situated just before the end (N1, N1') of the movement of that piston under load, said first sensor being connected, through an amplifier, to the said device for supplying hydraulic fluid to the jack assemblies responsive to detecting the arrival of said respective piston at said position such that this device automatically controls the beginning of an offload movement of the piston of one of the other jack assemblies in the direction of movement of said object relative to said assembly at a moment which precedes the arrival at the end of travel in the same direction, of the piston under load.
Hydraulic circuit for supplying hydraulic fluid to two jack assemblies according to a predetermined sequence of driving and returning steps such that there is no gap between the driving step of one of the jack assemblies and the following driving step of the other, each said jack assembly comprising a first chamber and a second chamber, and said first and second chambers being separated by a piston, and the first chamber of one of the jack assemblies being connected to the first chamber of the other jack assembly, said hydraulic circuit further comprising, for each jack assembly, a group of four valves operable responsive to the position of the associated piston of the corresponding jack assembly for selectively controlling the supply of hydraulic fluid to said corresponding jack assembly, said four valves forming two pairs of two valves and each of the two valves of the two pairs of two valves being connected together, and therefore having a common point, each of said pairs of each group being connected between said first chamber and said second chamber of the corresponding jack assembly, and a pump in each group for pumping said hydraulic fluid to the corresponding hydraulic jack under the control of said control valves, said pump being connected, in each group, between the said common point of one of said pairs of valves, and the said common point of the other pair of valves.
Hydraulic circuit for supplying hydraulic fluid to two jack assemblies according to a predetermined sequence of driving and returning steps such that there is no gap between the driving step of one of the jack assemblies and the following driving step of the other, each said jack assembly comprising a first chamber and a second chamber, the first and second chambers being separated by a piston, and the two first chambers being common, said hydraulic circuit further comprising, for each jack assembly, a group of four valves operable responsive to the position of the associated piston of the corresponding jack assembly for selectively controlling the supply of hydraulic fluid to said corresponding jack assembly, said four valves forming two pairs of two valves and each of the two valves of the two pairs of two valves being connected together, and therefore having a common point, each of said pairs of each group being connected between said first chamber and said second chamber of the corresponding jack assembly, and a pump in each group for pumping said hydraulic fluid to the corresponding hydraulic jack under the control of said control valves, said pump being connected, in each group, between the said common point of one of said pairs of valves, and the said common point of the other pair of valves.
Dependencies are inferred from the claim text.