US2746485A - Accumulator - Google Patents

Description

B. vN. ASHTON May 22, `1956 ACCUMULATOR Filed May l, 1953 A QN .vm mw @N 2 Q, om 2 Nm mi: lil /l mw l @TVI NN. S O\ Tm, mm. \N ON United States Patent" O ACCUMULATOR Benjamin N. Ashton, Kingston, N. Y., assignor to Electrol Incorporated, Kingston, N. Y., a corporation of Delaware 'l Application May 1, '1953, serial No. 352,550

s ciaims. (ci. 13s- 31) This invention relates to improvements in accumulators for hydraulic systems and it relates `particularly to an improved and simplified type of piston-type accumulator suitable for use in aircraft hydraulic systems and in other high or low pressure hydraulic systems.

It has beenproposed heretofore to provide pistontype accumulators which include a metallic cylinder having heads at its opposite ends and having a piston which is slidable lengthwise of the cylinder and divides it into a liquid-receiving chamber tobe connected to the hydraulic system' and a gas-receiving chamber to be lled with air or other gas under pressure.'v `In many of these prior accumulators, difliculty is encountered in providing piston rings on the piston which provide a sufficiently good seal with the cylinder wall to prevent escape of gas and liquid past the piston and mixing thereof with resultant adverse effects on the hydraulic system.

In my Patent No. 2,440,065, dated April 20, 1948, and in my co-pending application Serial No. 337,553, filed February 18, 1953, I have disclosed several forms of sealing means which eliminate leakage of the gas and hydraulic liquid past the seals between the piston and the cylinder and mixing of them in the gas or liquid chambers of the accumulator. This desirable result is achieved by using resilient sealing rings or the like on the piston or in the cylinder and providing means for maintaining a pressure diierential on opposite sides of the rings to thereby cause them to seat tightly against the cylinder and the piston to preclude leakage therebetween.

Even with my prior types of accumulators, the manufacture of the cylinder and the pistons and the provision of suitable cylinder heads and sealing means therefor produce engineering and production problems that render the accumulators more expensive and complex than is to be desired. Thus, in most of the prior accumulator-s, one or both ends of the cylinder have removable heads to permit access to the interior of the cylinder. Such removable heads require seals or packings therein to prevent escape of liquid and/or gas and, in some in stances, a safety mechanism has been provided to prevent removal of the cylinder =head while the pressure is still present in the hydraulic system or the accumulator.

`I have discovered that the construction of the accumulator can be greatly simplied and that the accumulator cylinder can be reduced in complexity so that it can be manufactured more readily and at lower cost. Such a cylinder can be provided with seals of the resilient ring type for cooperation with the piston in the cylinder, these rings being so located with respect to the cylinder that they are inherently subjected to different pressures on their opposite sides to obtain the sealing action referred to above.

For a better understanding of the present invention reference may be had to the accompanying drawing in which the single ligure is a View in longitudinal section through a typical accumulator embodying the present invention.

or sleeve 13 having piston` heads 14 `and 1,5 welded in its opposite ends. kIf desired, one or the other of the piston heads 14 and 15 may be omitted. i i

The tubular skirt 13 can be'formed of polished but not necessarily precision honed tubing, such as stainless steel tubing or the like and ititsi slidably within the cylinder 11 for free movement therealong. The `piston 12 does `not have to t the'cylinder 11 withinclose tolerances but their contacting surfaces should be smooth so that the piston moves freely in the `cylinder `without excessive radial play. i

The cylinder 11 of the accumulator is of -novel `con-y struction. It consists of two-opposed hollow cup like sections 16 and 17 which are of 'circular 'crosssection and generally `cylindrical shape, The cylinder section 16 has a head 18 `atits outer end which is in' tegral with it and is provided with a passage 19 inlwhich may be mounted an air check valve or `the lil ;e;thr ough which air or other` gas -under pressure is lintroduced into the accumulator to the leftjof `the piston 12. f'l`hc. cylinder section 16 has a thickened portion 20,-at .its right-hand end provided `with external threads 21.V

The cylinder section 17 isv similar to the sectionl` i in that it also has a cylinder head 22 yatV itsrghtThand end provided with a` passage and coupling` `23 enabling it to be connected to the hydraulicsystem;. .The lefthand end of the cylinder section 17 also has a` thickened portion 24 having a tubular extension 25 provided with internal threads 26 which are screwed on to the threads 21 of the section 16 to connect the cylinder sections in end-to-end relation, as shown in the drawing. v

The thickened portions 20 and 24 of the cylinder sections have internal circumferential grooves 27, 28, respectively, therein. The grooves 27 and 2S receive resilient sealing membersgsuch as, the O- ring seals 29 and 30 which bear against the bottoms of the grooves and the skirt 13 of the piston in all positions of the latter axially of the cylinder 11.

It will be apparent that when air or other gas under pressure is admitted into the cylinder to the left of the piston and the coupling 23 is connected to the hydraulic system, the piston will be displaced endwise in the ac cumulator cylinder as the pressures at opposite ends of it vary.

The ring seal 29 will be subjected to the pressure of the air on its left-hand side while the ring 30 will be subjected to the pressure of the liquid on its right-hand side. In order to provide maximum sealing effect with `the rings 29 and 30 the pressures on opposite sides of each of the rings 29 and 30 are kept unequal, as explained in my Patent No. 2,440,065. In my new accumulator the threadedy connection between the two cylinder sections 16 and 17 provides a suitable means for enabling the rings 29 and 30 to be subjected to unequal pressures. Thus, if the threads 21, 26 are not in gas-tight engagement, the space between the rings 29 and 30 will be at approximately atmospheric pressure while the pressures on the outer surfaces of the rings may be 1,000 lbs. per square inch or higher in an aircraft hydraulic system, for example. A porous packing 31 may be mounted within a groove 32 at the joint 33 between the two threaded sleeves to permit air to leave or enter the space between the rings 21, 26. If the threads are relatively tighttting or in substantially gas-tight relation, a radial bore 33 may be drilled through the sleeve 24 to communicate with the groove 32. In any event, the location of the sealing rings 29 and 30 makes it unnecessary to have the connection between the ends of the sleeves 16 and 17 leakproof. In fact, it is advantageous to have a.

leaky joint between the sleeves 16 and 17 to increase the sealing -eiciency of the rings 29 and 30.

It will be seen that the new accumulator is formed essentiallypof three pieces, not including the two .sealing rings l2,9 and 30'. The piston and accumulator sections do not have to be machined or honed to a precision i'it becausethe resilient seal-ing rings 29 andv 30 readily compensate for irregularities in the surface of the piston. The new accumulator does not need removable cylinder heads and the packings or seals which are required to maintain rthe heads inleak-tight relation to the cylinden. It maybe fabricated from tubing or from simple castings with a minimum ofr finishing and precision operations.

It-willl be understood that the accumulator can be made CFI in various sizes dependingy upon requirements and that if desired, ahigh pressure source, such as a small bag type accumulator, can be connected to the radial passage 33- to` enable the accumulator member to be used in low pressuresystems: as suggested in my co-pending application Serial No. 337,553. Therefore, the form of the invention described herein should be considered as illustrative and not as limiting the scope of the following claims.

I` claim:

1. An accumulator for hydraulic systems comprising a pair of hollow cylindrical members each having an open end andL an integralcylinder head at its outer end, means connecting said members with their open ends in opposition to form a cylinder having the connecting means substantially at its midportion, an elongated pistonslidable aX-iallytin said cylinder and' at all times extending into both ofsaid cylindrical members, resilient sealing members interposed between each cylindrical member and the piston, Vsaid'sealing member being located on opposite sides of said connecting means and engaging said cylinder and said piston in all positions of the latter in said cylinder, and a passage from the interior of said cylinder between said sealing members to the outside of said cylinder.

2. An accumulator for hydraulic systems comprising a cylinder, said cylinder including a pair of hollow cupshaped sections having complementally threaded open inner ends and integral cylinder heads at their outer ends, said cup-sections being screwed together to form a joint at about lthe middle of the cylinder and each having a groove therein adjacent to its open inner end, an elongated piston slidable in said cylinder, means to admit gas into and discharge it from said cylinder at said joint and resilient sealing means in each groove of said cup-sections on opposite sides of said jointand in` sealingy engagement with said` piston in all positions of said piston in said cylinder.

3. The accumulator set forth in claim 2 in which the means to admit and discharge gas comprises a passage through the wall of' said cylinder between said sealing means.

References Cited in the tile of this patent UNITED STATES PATENTS 1,590,587' McFarland June 29, 1926 2,360,731 Smith Oct. 17, 1944 2,411,229 Pratt Nov. 19, 1946 2,411,315 Ashton Nov. 19, 1946 2,437,586 Aber Mar. 9, 1948 2,440,065 Ashton Apr. 20, 1948

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