US2905458A

US2905458A - Hydraulically damped spring-biased pistons and cylinders

Info

Publication number: US2905458A
Application number: US652975A
Authority: US
Inventors: Edward M Mason
Original assignee: IMPAX Inc
Current assignee: IMPAX Inc
Priority date: 1957-04-15
Filing date: 1957-04-15
Publication date: 1959-09-22
Anticipated expiration: 1976-09-22

Description

Sept. z2, 1959 Filed April l5, 1957 E. M. MASON 2,905,458

HYDRAULICALLY DAMPED SPRING-BIASED PISTONS AND CYLINDERS 2 Sheets-Sheet 1 EDWARD M. MASON 4ATTORNEY Sept. 22, 1959 E. M. MASON HYDRAULICALLY DAMPED SPRING-BIASED PISTONS AND CYLINDERS 2 Sheets-Sheet 2 Filed April l5', 1957 FIG. 7.

i NV E NTO R EDWARD M. MASON www FIG. 6.

ATTORNEY United States Patent OFP HYDRAULICALLY DAMPED SPRING-BIASED PISTONS AND CYLINDERS Edward M. Mason, St. Johns, Mo., assignor to Iinpax,

2 Claims. (Cl. 267-1) This invention relates in general to spring devices and, more particularly, to a hydraulically damped springbiased piston and cylinder.

Spring operated, hydraulically damped devices are sometimes employed in mechanical toys, such as, for example, in a toy dump .truck for elevating the dump body. Similar devices also nd use as door closers, in which case the opening of the door compresses a yspring so as to energize the device, which energy is later released to provide a positive means for slowly closing the door. These devices usually employ a spring-biased piston and cylinder arrangement wherein the cylinder is lled with hydraulic fluid so as to provide a damping action which retards the movement of the piston as it is forced along the cylinder under the action of the spring. The piston and cylinder are usually machined to very close tolerances so that, upon movement of the piston within the cylinder, the damping action is provided -by reason of the hydraulic uid gradually moving from one side of the piston to the other through the small clearance space between the piston and cylinder as the piston travels within the cylinder. However, notwithstanding the use of vcarefully selected tolerances between the piston and cylinder, it has been found 4that frequently the piston will tend to bind within the cylinder, thereby causing the piston to chatter as it moves.

It is, therefore, a primary object of the present invention to provide a hydraulically damped spring-biased piston and cylinder wherein the piston is -freely slidable and will move smoothly without chattering or -binding within the cylinder.

It is also an object of the present invention to provide a device of the type Astated which is inexpensive to construct by reason of the fact that component elements can be impact extruded and thereby precise dimensional tolerances can be achieved very economically.

With the above and other objects in view, my invention resides in the novel -features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings (two sheets)- Fig. 1 is a perspective View of a hydraulically damped spring-biased piston and cylinder constructed in accordance with and embodying the present invention;

Fig. 2 is la sectional view taken along line 2-2 of Fig. l, and showing the device in fully extended or expanded position;

Fig. 3 is a sectional view, similar to Fig. 2, and showing the device in fully contracted position;

Figs. 4 and 5 are longitudinal sectional views of the cylinder and piston, respectively, forming part of the present invention and showing a-n intermediate stage of manufacture of the invention; and

Figs. 6 and 7 are sectional views, similar to Figs. 2 and 3, and showing a modied form of the present invention.

Referring now in more detail and by reference characters to the drawings, which illustrate practical embodi- Patented Sept. 22, 1959 ICC ments of the present invention, A designates a hydraulically `clamped spring-biased piston and cylinder device comprising a hollow cylinder 1 `formed preferably as an impact extrusion and provided at its lower end with a thickened portion 2 which forms a lshoulder 2', and at its lower end the thickened portion 2 is provided with an axially extending bore 3. At its upper end, the cylinder 11 is conically flared outwardly at 3 for reception of a cap 4 having a conically tapered side wall 5 which matches :the taper of the ared portion 3'. The flared portion 3" is bent over to form an annular retaining lip 6 whereby the cap 4 is held snugly and retentively in place. On its outwardly presented surface, the cap 4 is integrally provided with a lug 7 having an aperture 8 drilled therethrough by which one end of the cylinder 1 may be bolted, pinned, or otherwise secured to a suitable supporting surface (not shown). Mounted within the cylinder 1 Ifor reciprocating movement therein is a plunger assembly 9 including a hollow tubular piston rod 10 which projects through the bore 3, the latter being provided with an annular groove 11 for reception of a seal-forming O-ring 12 which bears against the outer surface of the piston rod 10. Adjacent its upper end, the piston rod 1t) is integrally provided with a plate-like piston 13 which is sized to conform substantially to the inner diameter of the cylinder 1. At its outer periphery, the piston 13 is provided with an annular groove 14 for snug-fitting reception of an O-ring 15, the latter being adapted to provide a seal between the piston 13 and the inner surface of the cylinder 1. At its outer end, the piston rod 10 is swaged over to provide an arcuate valve seat 16 for reception of a ball-type check valve 17 which Ibears thereagainst, the valve 17 being provided with a -diametrally extending aperture 18. Intermediate its ends, the piston rod 10 is provided with a shoulder 19 for supporting one end of a small coil compression spring 20, the other end of which bears against the ball valve 17 and normally urges said valve 17 against the arcuate abutment 16. The spring 20 is integrally provided with a short, axially extending rodlike extension 21 which Iprojects loosely through the aperture 18 in the ball valve 17. At a short distance below the piston 13, the piston rod 10 is provided with idiametrally

opposed ports

22, 23, for communication between the interior of the cylinder 1 and the inside of the hollow piston rod 10. Provided for sliding movement within the piston rod 10 and below the shoulder 19 is a small slidable auxiliary piston 24, the outer periphery of which is grooved for reception of a pair of spaced parallel O-

rings

25, 26, which form a seal between the auxiliary piston 24 and the interior wall of the piston rod 10, and disposed between the piston 24 and the lower end wall 27 of the piston rod 10 is a coil spring 27', the latter normally bearing against the auxiliary piston 24 and biasing it in the direction of the piston `13. Extending between the piston 13 and the cap 4 is a strong compression spring 28 which urges the plunger assembly 9 to the position shown in Fig. 2, so that the piston 13 seats on the shoulder 2. At its lower end, the piston rod 10 terminates in a lug 28 having an aperture 29 by which the piston rod can be `secured to a suitable supporting sur- `face (not shown). Slightly above the lower end wall 27 the piston rod 10 is provided with an air vent 29" for permitting communication to atmosphere from the lower side of the auxiliary piston 24. i

In the manufacture of the device A, the cylinder 1 and the piston rod y10 and its associated piston 13 are impact extruded so as to provide the two components shown in Figs. 4 and 5. The cylinder .1 so formed includes an extension 30, while the piston rod 10 is formed with concentric

axial extensions

3,1, 32, the latter, in effect, being an extension of the piston 13. In forming the completed plunger assembly 9, the spring 27 fol- 3 lowed bythe auxiliary piston' 2'4 are placed within the hollowA piston rod1'0; whereupon' the spring 20 and' ball' check valve 17 are placed within the piston rod 10 with the rod-like extension 21 projecting through the. aperture y 18% Iliegaaiial extension' 31 istlvie'n" swagdove to formi.

ther/alivia:seat 16'l` previously' described. The a'xial extensionn is' thenV4 bent` over toY form the annular groove 121" aridx the Gering 15' is' mounted therein.. `The axialextension 3`0ftof` the. cylinder 1`i's` bent inlvvardlfyV to form" the' groove: 11, whereupon lthe O-ringv 12"i's fittedtherein; Theplunger assembly 9 is then placed within the; cylinder' 1 vso` as: toassume the relativepositions shown in. Fig. 2; The ball valve 17' is thenY depressed with al suitabletooland oil or other hydraulic' liuid isrthen pouredi'nto the open end of the cylinde'r,`.whereupon"the oil" will pass through the aperture 18" and' iill the porftin"of" tl'1`e.piston rod 10` abovethe auxiliary piston. 2Q'. Oil' will"also`pa`ss` through the ports 22, '23,v and;l iill`the,

cylinder-1J on the lower" side of the piston 13;V 'I'hecoil" spring' ZB is then inserted' within the cylinder f1' and" theY remainder of the cylinder I above 'the piston 13^ille`d withoil,` whereupon the cap4 4 is-iittedin'the' end ofthe cylinder' Il In this connection, itshouldhe n'otedfthzlt-A si'ricetlie cap fisV formed with a conical surface 15",. the placement. of the cap 4 within the cylinder flwllreshape the eiidj'ofthe cylinderto form thenia'tcliingfii'ared.L pore tion 3, whereupon the end of the cylinder"l I bentV scribedf InV use, the deviceV A is normally in theY position shown` inf Fig.` 217 However, whenA the plungerasseinblynfis moved from the position shown in Fig. Z to thatlshow'n in Figl 3, the coil Vspring 2-8` will. be compressed andopen the check valve 17 to permit oil to. flow

therethrough andthrough theports

22, 23,'. to-ll the cylinder'l l1; onthe lower side'of'fthe piston 13;- Since the. hydraulicvuid. is

relatively incompressible, the volume occupied by the ,y

pistonrod'l will. causelnan increase in the pressurewithin the cylinder 1i on the lower side of the piston 13.

However, this increase in pressure is` relievedby virtue of suoliv pressure acting. on the upper surface of the` auxiliary piston 24. and forcing the-.piston` 24 downvvardly4 against andcompressing the coil spring 27'. Upon re'- pass through thel ports 22, 2.3, `and Yseep slowly-through the aperture18 inthe ballvalve 717 -toprovide a damping` action.

It is. also possibleY to provide a modihed form'ofhwy-l draulically damped spring-biased piston' and cylinder device Al of the type shown in Figs. 6- and-7"- The devicefA! is similar to thev device' A, previously described;

However, in this form of the invention the auxiliary'V piston. 24 and` spring' 27 employed in the device: Aareeliminated and the compression springZOf' is supportedW at. its lower endby means of a pin 33y secured in, and extending` diametrally through,A the pistonrod-flf'., In

assembling the device- A', the plunger assembly 9 is placed within the cylinder 1 in the manner shown in Fig.'A 6, whereupony the ball valve 17" is .depressed'fby any' suitable,tv tool anda measuredfamontof oilrisffpoured into-thecylinderfl' so as to completely lill vthe hollow piston rod and also the'lower. end ofthe'cylinder 1,"

to a level above the ports 22.', 23', such as shown in Fig. 6'; The' compression spring 28" i'sthen inserted into the cylinder 1 and the remainder of the cylinder 1' above the piston 13 is lled with oil, whereupon the cap 4 is placed in the cylinder 1 in the same manner as in the device A, previously described. An air space a will then be formed between the oilfini'the. lower part of the cylinder andthe. piston 1.3,. so that whenl the plunger assembly 9" is' mved from the positionshovvn-in Fig.l 6) to the position shown in Figi 7, theinc'rea'se in'pressure due to.' the'volume:o'ccujgxieil` by .the piston. rod- 10" will; bei' oompesatedl forv by'f'reasorr or rhefaee thatL the' air in the spaee-a/willbe compressed. and consequently' reduced in volume, suoliA as showniri Fig'. 7.

It should be understoodfthat/ changes and modications in the form, construction, arrangement, and combination of the several parts of the hydraulically damped spring-'biasedV piston and the cylinder maybe madel and substituted for those hereinY shown yand described without'departin'g from' the n'atine` and principle of my in# ventiom n v I Y' llavi'rig` thus described? niv" invention, what I. claim and desire to secur'eby Letters Patent is;

` k'l-i.. A device ofthe',leliarasterdescribed.adapted` for useY iiiA mechanical toys and the like,l said! device comprisingl af cylinder. containingy hydraulic. a. piston. mounted for shiffing'. movement within the cylinder and being` sealed with respect. thereto, a compression springv interposedbetween the. piston. and oneenii of theoylindeg a;

rod extending;` from the.' piston and being", provided with a1 least one. port therein. by which hydrauf licffliiidcan'owinto andout` of the piston rod, achecle valve mountedinsaidv piston rod. and having.anaperture,L

extendingi th'eretliro'uglrl and. spring means biasing. said check valve, against andy closingoif one end of thepiston'r rod, said-Y( spring means' having a projection passing;`

loosely/through said. aperture.

2:l A devicelo the character.described;adapted-forfuse,` in. mechanical: toys andE the like, saiddevicev comprising aJM cylinder'containing.hydrauliciluid, a piston mounted.

forfnshiftingr movement withinthe cylinder and'being;

sealed with.. respect.V thereto, a compression' spring; Vinterposed between the piston and one end of the cylinder, aA hollow` pistonv rod, extending frornther piston and being providedwith-V at least oneporty therein by which' hydrau-i lic fluid-'can flowA into and out of the piston rod, Vacheck valve mounted in.r saidpiston rod and having-an aperture,

extending therethrough, spring means biasingsaidehecl Val-ve against and closing oi one end` of the. piston' rod,

saidvspring'rneansI having' 'a projection passing'` loosely through said aperture, an; auxiliary.y piston slidably mountedA in the hollow piston: rod'andbeingini spaced relation tol l said check valve, and means for biasing-the auxiliary piston. insthedirection of'. the check valve.

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