Expansible chamber devices – Relatively movable working members – Interconnected with common rotatable shaft
Patent
1998-01-16
1999-12-21
Ryznic, John E.
Expansible chamber devices
Relatively movable working members
Interconnected with common rotatable shaft
92130A, 92130D, F15B 1508
Patent
active
060034327
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an actuator of the type comprising a jack, having a first and second piston cooperating with a control spindle, for example in order to rotate the shaft of a valve device through a fraction of a turn.
BACKGROUND
Actuators of the type comprising a single-action jack with springs for returning to a preferred position should the supply to the working chamber cease are already known. The energy accumulating in the springs which are compressed under the supply pressure should be sufficient to perform this movement of the pistons and rotate the control spindle.
Usually, the springs bear against the pistons at one end and against the cylinder heads or a fixed part, at the other. If shock absorbers are provided, they are arranged in the same way. In the preferred position, the pistons are located closest to one another. Between the pistons is the working chamber. The supply of pressurised fluid to the working chamber moves the pistons apart counter the force of the springs, thereby compressing them. In the event of an interruption to the main supply causing a drop in pressure in the working chamber, the energy accumulated in the springs pushes the pistons back towards the preferred position.
Owing to the fact that the compression of the springs takes place between the pistons and the cylinder heads of the fixed jack, the entire arrangement is relatively bulky. In order to fix the cylinder heads to the bodies of the jack, very long screws are needed. Moreover, as the springs bear on a fixed component at one end and on a movable component at the other, only some of the energy is recovered.
The aim of the invention is to improve the construction of an actuator of the type comprising a jack.
SUMMARY OF THE INVENTION
The actuator of the type comprising a jack according to the invention is characterised in that energy accumulating cartridges and/or shock-absorbing elements are placed between the pistons, acting at one end against the first piston and at the opposite end against the second piston.
The arrangement of the cartridges and/or shock-absorbing elements in what is normally a dead space makes optimum use of the space available. At the same time, both the active and reactive energy of the cartridges is utilised, as the cartridges bear on two movable components.
The construction of a shock-absorbing system in a double-acting jack with shock-absorbing elements between the pistons has the same advantages of being compact. The construction of a single-action actuator with cartridges and shock-absorbing elements arranged between the pistons combines the advantages of safety and shock absorption in a single system.
The use of the helical springs which cooperate with an element which limits the travel of the springs makes it possible to prefabricate spring cartridges. Thanks to these spring cartridges, the actuator is simple to assemble and a variety of desirable spacing forces is achieved by the use of springs with a suitable recoil constant, while keeping the same dimensions. At the same time, the element inside reduces the buckling of the springs. The element inside comprises two elements functioning as rods which are partially guided in a central structure.
To reduce the buckling still further the central structure is provided with a collar and the spacer springs are divided into two bundles, arranged on either side of the collar.
In a preferred embodiment the element also acts as a shock absorber for combining the functions of safety and shock absorption.
BRIEF DESCRIPTION OF THE FIGURES
The accompanying drawings illustrate the invention:
FIG. 1 shows a single-action actuator in axial section on the line BB in FIG. 2,
FIG. 2 shows the actuator in section on the line AA in FIG. 1,
FIG. 3a, 3b show a double-action actuator with shock absorbers, in axial section,
FIG. 4 shows a first spacer spring and a spacing-limiting element, in section,
FIG. 5a-5d show a section through a second spacer spring and a spacing-limiting element and different stages of assembly,
REFERENCES:
patent: 1835919 (1931-12-01), Waseige
patent: 3336842 (1967-08-01), Adelt
patent: 4354424 (1982-10-01), Nordlund
patent: 4564169 (1986-01-01), Nordlund
patent: 4651626 (1987-03-01), Messina
patent: 4905574 (1990-03-01), Trevisan
patent: 4949936 (1990-08-01), Messina
patent: 5003864 (1991-04-01), Dyer
patent: 5653419 (1997-08-01), Uchisawa et al.
KSB S.A.
Ryznic John E.
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