Pressure Actuated Assembly Extendable by Fluid Pressure and Retractable by Spring Action

This invention relates to a pressure actuated assembly which can extend and retract, and more particularly to a pressure actuated assembly extendable by fluid pressure and retractable by spring action.

A fluid pressure actuated assembly is commonly used in a pressure gauge, a height-adjustable chair, and the like. It typically employs a hydraulic cylinder in which a piston moves. The hydraulic cylinder type assemblies suffer from the following disadvantages:

(1) The space between the piston and the cylinder wears easily, even if various oil rings are provided therebetween.

(2) When substantial liquid pressure is applied to the interior of the hydraulic cylinder, the resulting leakage of hydraulic oil may occur in the hydraulic cylinder, causing inaccurate travel of the piston.

(3) When a movable mechanical component is associated with the hydraulic cylinder, if the displacement of the mechanical component is dependent on the travel of the piston, the leakage of the hydraulic oil in the hydraulic cylinder will cause inaccurate displacement of the mechanical component.

It is therefore the main object of this invention to provide a simple pressure acutuated assembly extendable by fluid pressure and retractable by spring action.

According to this invention, a fluid pressure actuated assembly includes a casing made of a flexible resilient material, such as rubber or polyurethane, a coiled tension spring sleeved on the casing for biasing the casing to a retracted position, and a coiled spacing spring interposed between the tension spring and the casing for preventing any wall of the casing from being clamped between any two adjacent turns of the tension spring.

Other features and advantages of this invention will become apparent in the following detailed description of the preferred embodiments of this invention with reference to the accompanying drawings in which:

FIG. 1 is a sectional view of a gas pressure actuated assembly according to a first embodiment of this invention;

FIG. 2 is a sectional view of a liquid pressure actuated assembly according to a second embodiment of this invention;

FIG. 3 is a sectional view of a liquid pressure actuated assembly according to a third embodiment of this invention; and

FIG. 4 is a schematic sectional view illustrating how to employ the assembly of this invention in an automatically ascending apparatus, such as a height-adjustable chair.

Referring to FIG. 1, a gas pressure actuated assembly 100 of this invention includes a hollow cylindrical casing 101 of rubber which has a closed upper end, an open lower end, and a lower end outward flange 102. The lower end outward flange 102 is clamped between a base 103 and a rigid lower ring 104 which is fastened to the base 103 by lock belts 105 for establishing an air-tight seal between the lower ring 104 and the base 103. The lower ring 104 has an upward annular projection 106 extending upward from its inner periphery. The upward projection 106 has external threads 107 on which the lower end of a first coiled tension spring 108 is tightly sleeved. A rigid upper disk 109 has a downward annular projection extending downward from its outer periphery so that the closed end of the casing 101 is capped with the upper disk 109. Because the upper disk 109 is retained between the closed end of the first casing 101 and a diameter-reduced fastening turn 110 of the first tension spring 108, the casing 101 is biased by the first tension spring 108 to move toward a retracted position shown in FIG. 1. A pressure indicating means 111 (only part of which is shown) is installed on the upper disk 109 so as to indicate the pressure valve in accordance with the displacement of the upper disk 109.

When a compressed gas is applied to the interior of the casing 101 through an adapter 112 provided on the base 103, the casing 101 extends upward a distance proportional to the magnitude of the pressure applied so that the pressure indicating means 111 indicates the pressure to be measured in accordance with the displacement of the upper disk 109.

Referring to FIG. 2, a liquid pressure actuated assembly 210 of this invention includes a hollow cylindrical oil tank 211 of a flexible resilient material, such as rubber or polyurethane, which has a closed lower end, an open upper end, and an upper end outward flange 212. The oil tank 211 is filled with hydraulic oil. The upper end outward flange 212 is clamped between a mechanical component Y and an upper ring 213 which is fastened to the component Y by lock belts 215 for establishing a liquid-tight seal between the upper ring 213 and the component Y. The upper ring 213 has a downward annular projection 215 extending from its inner periphery. The downward projection 215 has external threads 216 on which the upper end of a second coiled tension spring 218 is tightly sleeved. A rigid lower disk 217 has an upward annular projection extending from its outer periphery so that the closed end of the oil tank 211 is capped with the lower disk 217. Because the lower disk 217 is retained between the closed end of the oil tank 211 and a diameter-reduced fastening turn 219 of the second tension spring 218, the oil tank 211 is biased by the second tension spring 218 to move toward a retracted position shown in FIG. 2.

The mechanical component Y is formed therethrough with a vertical oil flow path X which is communicated with the interior of the oil tank 211 at its lower end. In use, a hydraulic apparatus may be connected to the upper end of the component Y, as described hereinafter in detail. Upon the application of a load W to the hydraulic apparatus, the hydraulic oil increased in the oil tank 211 causes the oil tank 211 to extend downward. When the load W is removed from the hydraulic apparatus, the oil tank 211 retracts to extrude the previously increased hydraulic oil therefrom through the oil flow path X.

Referring to FIG. 3, to prevent any wall of the oil tank 211 from being clamped by any two adjacent turns of the second tension spring 218 when the oil tank 211 is retracted, a coiled spacing spring 220 may be interposed between the second tension spring 218 and the oil tank 211. The length of the spacing spring 220 is much smaller than the second tension spring 218. Furthermore, to prevent the oil tank 211 from being hurt by the ends of the spacing spring 220, a rigid protective ring 230 may be provided therebetween.

FIG. 4 shows the association of an oil pressure actuated assembly 20 of this invention with a hydraulic cylinder 10 which includes a cylinder body 11, an upper cover 12, a piston 13, a piston rod 14, and an oil seal 15. The seat of a height-adjustable chair (not shown), represented by a character W, is secured to the upper end of the piston rod 14.

The oil pressure actuated assembly 20 includes an oil tank 21 which has a closed lower end, an open upper end, and an upper end outward flange 22. The oil tank 21 is filled with hydraulic oil. The upper end outward flange 22 is clamped between a connecting block 30 and an upper ring 23 which is fastened to the block 30 by lock belts 24 for establishing a liquid-tight seal between the upper ring 23 and the block 30. The upper ring 23 has a downward annular projection 25 extending from its inner periphery. The downward projection 25 has external threads 26 on which the upper end of a third coiled tension spring 28 is tightly sleeved. A rigid lower disk 27 has an upward annular projection extending from its outer periphery so that the closed end of the oil tank 21 is capped with the lower disk 27. Because the lower disk 27 is retained between the closed end of the oil tank 21 and a diameter-reduced fastening turn 29 of the third tension spring 28, the oil tank 21 is biased by the third tension spring 218 to move toward a retracted position shown in FIG. 4.

The connecting block 30 connects the oil pressure actuated assembly 20 to the hydraulic cylinder 10 and is formed therethrough with a vertical oil flow path or oil pipe 31 which is intercommunicated at its two ends 32 and 33 with the hydraulic cylinder 10 and the oil tank 21. A throttle valve 34 is installed in the oil pipe 31 for regulating the oil flow from the hydraulic cylinder 10 to the oil tank 21. With the throttle valve 34 provided in the oil pipe 31, when the piston rod 14 is depressed, the oil will flow slowly from the hydraulic cylinder 10 to the oil tank 21. A stop valve 35 is also installed in the oil pipe 31 and equipped with a control handle 40 so that it can be manually closed to stop the oil flow between the hydraulic cylinder 10 and the oil tank 21.

In operation, when nobody sits on the chair seat W and the stop valve 35 is open, the tension force of the third tension spring 28 causes the oil tank 21 to retract so that the oil flows from the oil tank 21 to the hydraulic cylinder 10, thereby ascending the piston rod 14 to an upper limit position. When it is desired to adjust the height of the chair seat W, the stop valve 35 is opened, and then the operator sits on the chair seat W so that the chair seat W descends slowly until it reaches a desired position. Subsequently, the stop valve 35 is closed to locate the chair seat W in the desired position. It is understood that the oil tank 21 extends while the piston rod 14 descends.

With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated in the appended claims.