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US 5,722,643 AGranted
Temperature compensated safety gas spring
AssigneeAVM, Inc.
InventorsJames B. Chamberlin, Alfred W. Siman
Life of this patent
Estimating the term…
Abstract
A gas spring includes a piston assembly or pack having an additional seal, pressure relief valve, and check valve that increases the output force of the gas spring. Various temperature compensation structures, also added to the piston pack, permits this increase to vary from zero at higher ambient temperatures to a maximum value at very cold temperatures thus achieving a temperature compensation, which varies, in an analog manner, inversely in response to the temperature changes.
Claims8
An improved gas spring comprising:
- a) a cylinder defining an internal chamber, which is adapted to be filled with gas under pressure, higher than atmospheric pressure, and having an open end and a closed end;
- b) a piston rod having one end received, in sealed relation to the cylinder, in the open end of the cylinder and being movable toward and away from the closed end of the cylinder;
- c) a piston assembly carried by the one end of piston rod and being movable within the internal chamber, the piston assembly separating the internal chamber into a compression compartment, which is adjacent to the closed end of the cylinder, and an extension compartment, which is adjacent to the open end of the cylinder, with the volumes of the compartments varying in accordance with the position of the piston assembly within the cylinder;
- d) first means, which together with the piston assembly, for permitting gas to pass from the extension compartment to the compression compartment in response to movement of the piston assembly toward the extension compartment;
- e) means for by-passing gas from the compression compartment to the extension compartment when the piston assembly moves toward the compression compartment;
- f) second means for permitting gas to pass through the by-pass means, when the piston assembly moves toward the compression compartment and when the pressure of the gas in the compression compartment exceeds the pressure of the gas in the extension compartment by a predetermined amount;
- g) temperature compensation means for changing the predetermined amount, in an analog manner, inversely with changes in the temperature so that the force exerted by the gas spring will be maintained substantially uniform regardless of changes in temperature throughout the anticipated range of temperature to which the gas spring will be exposed, with the temperature compensating means including a spool-shaped valve body having first and second end flanges and a central, reduced diameter portion disposed between the end flanges, the first end flange being proximal to the extension compartment and having a smaller diameter than that of the chamber to define a flow passage permitting gas flow between the first end flange and the cylinder, the second end flange being proximal to the compression compartment and forming a close, free-sliding fit with the cylinder;
- and a flow passage opening to the compression compartment and terminating in a valve seat positioned the middle portion of the spool-shaped valve body.
5 more elements
An improved gas spring comprising:
- a) a cylinder defining an internal chamber, which is adapted to be filled with gas under pressure, higher than atmospheric pressure, and having an open end and a closed end;
- b) a piston rod having one end received, in sealed relation to the cylinder, in the open end of the cylinder and being movable toward and away from the closed end of the cylinder;
- c) a piston assembly carried by the one end of piston rod and being movable within the internal chamber, the piston assembly separating the internal chamber into a compression compartment, which is adjacent to the closed end of the cylinder, and an extension compartment, which is adjacent to the open end of the cylinder, with the volumes of the compartments varying in accordance with the position of the piston assembly within the cylinder;
- d) first means, which together with the piston assembly, for permitting gas to pass from the extension compartment to the compression compartment in response to movement of the piston assembly toward the extension compartment;
- e) means for by-passing gas from the compression compartment to the extension compartment when the piston assembly moves toward the compression compartment;
- f) second means for permitting gas to pass through the by-pass means, when the piston assembly moves toward the compression compartment and when the pressure of the gas in the compression compartment exceeds the pressure of the gas in the extension compartment by a predetermined amount;
- g) temperature compensation means for changing the predetermined amount, in an analog manner, inversely with changes in the temperature so that the force exerted by the gas spring will be maintained substantially uniform regardless of changes in temperature throughout the anticipated range of temperature to which the gas spring will be exposed, with the temperature compensation means including a valve member that is biased by spring means to a position that prevents flow of gas through the passage with the bias exerted by the spring means changing inversely as the temperature changes, and with the spring means including first and second coil compression springs, with one end of the first spring being connected with one end of the second spring by a member whose dimension changes inversely proportionally with changes in temperature.
4 more elements
Dependencies are inferred from the claim text.