US2952267A

US2952267A - Self-regulating fluid pressure operated power cylinder

Info

Publication number: US2952267A
Application number: US698255A
Authority: US
Inventors: Reis Smil
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-12-06
Filing date: 1957-11-22
Publication date: 1960-09-13
Anticipated expiration: 1977-09-13

Description

Sept. 13, 1960 S. REIS SELF-REGULATING FLUID PRESSURE OPERATED POWER CYLINDER /5 I 4 I ,2 25* F f I .15 (24 9/72 10 7 2.5 86 80 C 1 v 7 F 1 10 *TTgJ5 3 Filed NOV. 22, 1957 INVENTOR.

United States Patent SELF-REGULATING FLUID PRESSURE OPER- ATED POWER CYLINDER Smil Reis, Via Mauro Macchi63, Milan, Italy Filed Nov. '22, 1957, Ser. No. 698,255 Claims priority, application Italy Dec. 6, 1956 2 Claims. or. 131-115 This invention relates to a fluid pressure operated power cylinder adapted to open and close automatically the supply of the operating fluid, when its pressure reaches a pre-set upper, respectively lower limit, thus relieving the source of fluid pressure from load, at the upper limit.

This invention may also be used in any fluid pressure operated power system, for maintaining the fluid pressure between pre-set limits. It provides a very simplified construction, which operates with eifective precision in response to exact pressure limits, and avoids any condition that may cause to any components, what is commonly known as chattering.

The objects, advantages and aims of this: invention, will appear substantially, from the description given below with reference to one embodiment and its operation, shown schematically in the accompanying drawing wherein Fig. 1 shows a sectional view taken axially through the power cylinder; Fig. 2 shows the power cylinder with its components in one operative position; 'Fig. 3 shows the power cylinder with its components in a second operative posit-ion; and Fig. 4 shows the power cylinder in an arrangement for operating a power user.

With reference to the Fig. l, the cylinder body 1 has a closed upper end, a lateral inlet port 2, and a lateral outlet port 3. The inlet port 2 is situated between the outlet 3 and the closed end of the cylinder 1. A second outlet port '4, is situated at the closed end of said cylinder 1.

In the bore 5 of the cylinder 1 is arranged slidably, a compound piston 6-8 having a first upper part 6 with a stem 7, and a second lower part 8 axially slidable thereon Said lower part 8 is kept at a certain distance from said upper part 6, urged by a spring against a retainer 9 fixed to said stem 7. Said spring 10 is arranged between said

parts

6 and 8, in an intermediate portion of their length, said intermediate portion being recessed to form a first chamber 11.

The upper part 6 is shaped so as to form in co-operation with the closed end of the cylinder 1, a second pressure chamber 12.

The first chamber 11 is in permanent communication with the inlet 2, while the pressure chamber 12 is permanently communicating with the outlet 4. A duct 13 in said upper part 6 connects the

chambers

11 and 12, and a valve 14, loaded by a spring 15, controls the passage through said duct 13, so that fluid can flow from chamber 11 into chamber 12, but not inversely.

A spring 16, arranged between the retainer 9 and a second retainer 17 fixed to the open end of the cylinder 1, urges said compound piston 6-8 upwards to the inner end of its stroke. At this position, the lower part 8 closes the outlet 3.

A second bore 18 with a second piston 19 therein, is situated at the open end of the cylinder 1, perpendicularly to the main bore 5. A plug 20 fixed to the second piston 19, projects through a hole of the cylinder wall, into the main bore 5, and is adapted to stop the lower part spring 26. The plug 20 fits the hole through which it projects into the main bore 5, so that fluid from the restricted portion 22 cannot pass into said main bore 5. The restricted portion 22 is communicating through a duct 23and a port 24, with the first chamber 11, and

' through said duct 23 and a second port 25, with the chamber 12. The port 25 is situated so that it remains normally closed by the upper part 6 of the compound piston 68, and is opened when said part reaches the outer end of its stroke, while the port 24 is situated so that it is closed by the same part 6, before the port 25 is opened.

When the invention is to be used as a power cylinder, a cook 27, (Fig. 4); or any known device adapted to open and close the outflow from chamber 12, will be fitted to the outlet port 4, and the power will be transmitted to the power user not shown, through the piston stem 7, to which said power user will have to be connected. In this case, the cylinder will work under load, when the outlet 4 will be closed.

For use to maintain pressure between pre-set limits in a fluid pressure operated system, the pressure pipe (not shown) through which pressure fluid is supplied to said system will have to be connected to said outlet 4.

The fluid supplied through the inlet port 2 reaches the pressure chamber 12 through the first chamber 11, the duct 13 and the valve 14, the latter being forced to open, by the same pressure fluid. With the outlet 4 opened, there is no rise in pressure more t-hannecessary to keep the valve 14 open and to overcome the resistance to flow. When the outlet 4 is closed, the pressure in chamber 12 rises and the compound piston 68 moves as one solid piece, downwards to the open end of the cylinder 1, until the lower edge of its lower part 8 will be stopped by the plug 20. The pressure will continue to rise until the tension of the spring 10 is overcome. At this point, while the lower part 8 is withheld by the plug 20, the upper part 6 continues to move downwards, closing first the port 24 (-Fig. 2) and opening successively the port 25 (Fig. 2 and Fig. 3).

Pressure is now admitted within the restricted portion 22 of the bore 18, urging the piston 19 to withdraw the plug 20, so that the spring 10, whose tension, properly selected, is higher than that of the spring 16, will force rapidly the lower part 8 of the compound piston 6-8, downwards to the outer end of its stroke, thus opening the outlet 3. The pressure within the first chamber 11, and thus also that of the source that supplies it, is therefore relieved, while the pressure in chamber 12 remains maintained, the valve 14 closing the passage back to the duct 13.

When the outlet '4 is opened, or the pressure in the pressure pipe to it connected, drops below a limit depending upon the tension of the spring 16, the compound piston 6-8 is urged again upwards to the inner end of its stroke, closing. the outlet 3 and the port 25, and opening the port 24, through which also the second piston 19 and the restricted portion 22 of the bore 18, will be the upper pressure limit setting may be regulated from outside, by means of any well known arrangement adapted for this purpose.

It will further be remarked that there is no possibility for chattering of "any of the .movable components of this invention, because there isnone that can remain in an uncertain condition, wherein the opening or a fluid passage has been started, but cannot be completed.

I claim:

1. A self regulating 'fiuid pressure-operated power'cylinder comprising a cylinder body with a cylinder bore, a first upper piston part therein and a stem fixed theretotfor transmitting the piston power to any power user outside said power cylinder, :21 second lower piston part carried slidable on said stem, a spring between said piston parts urging the lower piston .part against a retainer of said stem apart from the upper piston part, a recessed portion between said upper and lower piston part forming a first chamber in said cylinder bore, an inlet port opening permanently into said first chamber for continuously ad mitting pressure fluid therein, a relief outlet located along the cylinder bore so as to be fully opened into said first chamber by the lower piston part when said lower piston part is at the outer end of its stroke, a second chamber pressure fluid from the first into the second chamber but not inversely, resilient .means urging the stem and the upper piston part to the inner end of its stroke, withdrawable springloaded means to stop the lower piston part along the piston stroke at a position just before the relief outlet begins to open and fluid pressure operated means for withdrawing :said springloaded means so that the lower piston part can be freely displaced to the outer end of its stroke by its expanding spring, thus opening fully said relief outlet.

2. A self regulating fluid pressure operated power cylinder as in claim 1, including a duct for transmitting fluid pressure to actuate the withdrawing means, a port connecting said duct-to the first chamber and another port for the fluid under pressure formed between the upper piston part and the upper closed end of the cylinder bore, an outlet port of said second chamber for the egress of said fluid under pressure therefrom, the upper piston part separating said first from said second chamber, a duct and a valve between said chambers for admitting connecting said duct to the second chamber, the said other port being kept normally closed by the upper piston part and located along the cylinder bore so that it is uncovered when said upper piston part reaches the outer end of its stroke, and the said port being normally open and located so that it is closed by the upper piston part just before said other port is uncovered.

References Cited in the file of this patent UNITED STATES PATENTS 2,732,851 Ashley et :al Jan. 31, 1956 2,733,727 Trevaskis Feb. 7, 1956 FOREIGN PATENTS 519,429 Great Britain Mar. 27, 1940