US2993472A - Hydraulic cylinder - Google Patents

Description

c. s. EINSIEDLER 2,993,472

HYDRAULIC CYLINDER 2 Sheets-Sheet 1 In m .m 4

4 INVENTOR. CHARLES STEPHEN EM/EDLER .7 a) V fld uzmzflmd ATTORNEY lrlf/ Ii i July 25, 1961 Filed June 6, 1960 2 Sheets-Sheet 2 Filed June 6, 1960 FIG. 4

mmwok CHARLES STEPHEN 'E/MS/EDLER ATTORNEY United States Patent 2,993,472 HYDRAULIC CYLINDER Charles Stephen Einsiedler, 67 King Philip Circle, Warwick 5, RI. Filed June 6, 1960, Ser. No. 34,118 Claims. (Cl. 12138) This invention relates to a hydraulic cylinder and more particularly to a hydraulic cylinder comprising fewer parts than heretofore.

One of the objects of the present invention is to provide a hydraulic cylinder for use in high pressure hydraulic systems and which is economical to manufacture and efiicient to operate.

Another object of the present invention is to provide a hydraulic cylinder in which the passage of fluid is through the medial area of the piston with a consequent minimum loss of effective piston area.

And still another object of the present invention is to provide a maximum area in a cylinder or piston chamber, which fluid under pressure may act upon.

Other objects of the present invention will be pointed out in part and become apparent in part in the following specification and claims.

Referring to the drawings in which similar characters of reference refer to like parts:

FIGURE 1 is a plan view of the new and improved hydraulic cylinder.

FIGURE 2 is a transverse cross sectional view taken along line 2-2 of FIGURE 1.

FIGURE 3 is a view similar to FIGURE 2 showing the relative movement between piston and cylinder.

FIGURE 4 is a view similar to FIGURE 2 illustrating a modified form of piston.

FIGURE 5 is a view similar to FIGURE 2 illustrating still another modified form of piston.

In the past a hydraulic cylinder consisted of a tube closed on opposite ends by means of bolsters or heads. A piston was slidably mounted in the tube. One end of the tube was provided with a collar. The piston rod was slidably mounted in the collar. A coil spring was interposed between the collar and the piston head to yieldingly urge the piston head to a position in one end of the tube. Fluid admitted through one bolster entered the tube to act on the piston head to move the piston in a direction against the tension of the spring. The disadvantages of this construction were: First, alignment of the bolsters with the tube. Secondly, the cost of manufacturing and assembling the many parts. Thirdly, the clearance between the parts had to be relatively great to prevent binding of the moving parts. Fourthly, these structures, because of the excessive clearance, would not operate at high fluid pressures.

The present structure obviates these disadvantages by providing for a close tolerance sliding fit between piston and cylinder. The piston engages the cylinder for the full length of both their lengths in work starting position. The axial orifice in the piston permits the piston to be a full length piston head. The close tolerance between the piston (head) and cylinder is in and of itself a fluid seal. At low pressure the relation is air tight. At high pressure the fluid packing is assisted in its fluid tight relationship by the close tolerance relationship.

The axial fluid passageway in the piston permits the fluid to act upon a greater area of the base. A greater work surface is provided in this construction over prior art constructions.

Reference is made to the drawings wherein is shown the new and improved hydraulic cylinder, generally indicated by reference character 10. A cylinder or piston chamber, generally indicated by reference character 11, consists of a cylindrical side Wall l2having a base 13 "ice which closes one end thereof; and an outwardly extending lip 9. Internally, the cylinder or piston chamber 11 is provided with a piston engaging surface 14 and a fluid engaging work area 15. The piston chamber 11 is open on one end to provide a likeness to an open ended vessel or cooking pot without a cover.

A piston 16 is provided with an axial passageway 17 having a threaded area 17A in one end. Externally piston 16 is provided with a sliding surface 16A having a circular groove 18 on one end and a reduced neck portion 19 which terminates the other end. A tapered shoulder 20 is formed between sliding surface 16A and neck portion 19.

Sliding surface 16A slidably engages piston engaging surface 14. Sliding surface 16A engages piston engaging surface 14 with a sliding fit which is an air tight relationship. Air cannot pass between sliding surface 16A and the piston engaging surface 14.

One of the advantages of the present structure is that sliding surface 16A may be manufactured by the inexpensive but extremely accurate method of centerless grinding. It is the extreme accuracy in manufacture between sliding surface 16A and piston engaging surface 14 which creates the air tight relationship and sliding fit.

A packing 21 is provided in circular groove 18 so that fluid at extremely high pressure cannot pass between sliding surface 16A and piston engaging surface 14. The packing creates a fluid tight seal.

A housing consisting of a cylindrical side wall 23 is provided with a cover 24 on one end and an outwardly extending flange 25 on the other end. A chamber 26 is formed between side Wall 23 and cover 24. Cover 24 is provided with an axial orifice 27'. Outwardly extending flange 25 is provided with bolt holes 28, 29.

A thrust plate or bed 30 is provided with tapped holes 31, 32 and a bore 36 provided with a tapered annular recess 37. Thrust plate 30 represents any plate upon which the device is mounted. Bolts 33, 34 passing through bolt holes 28, 29, respectively, secure outwardly extending flange 25 to thrust plate 30 through tapped holes 31, 32, respectively.

A pipe connection 35 is secured to piston 16 through threaded area 17A to provide a means of attachment between piston 16 and a source of fluid pressure (not shown).

The hydraulic cylinder 10 is assembled in the following manner: Piston 16 abuts thrust plate 30 with neck portion 19 located in bore 36 and tapered shoulder 20 abutting tapered annular recess 37. Packing 21 is inserted in circular groove 18. Piston chamber 11 is slid over piston 16 with sliding surface 16A engaging piston engaging surface 14. A coil spring 40 is slid over piston chamber 11 with one end of coil spring 40 resting against outwardly extending lip 9. The housing is next placed in position with piston chamber projecting through axial orifice 27 and the other end of coil spring 40 resting on cover 24. Bolts 33, 34 are then slid through bolt holes 28, 29, respectively, with bolts 33, 34 secured in tapped holes 31, 32, respectively. In this manner outwardly extending flange 25 is secured against thrust plate 30.

In operation fluid under pressure will enter axial passageway 17 through a hose connected to pipe connection 35 secured to threaded area 17A. The fluid will act against surface 15 and thereby force piston chamber 11 downwardly in the direction of the arrow in FIGURE 2, against the tension of coil spring 40 as illustrated in FIGURE 3. Thus performing a work stroke.

The pressure is released on the hydraulic fluid releasing piston chamber 11 to the action of coil spring 40, to place piston chamber 11 in initial starting position as illustrated in FIGURE 2.

It will be noted that sliding surface 16A is provided with an accurate diameter dimension and an extremely smooth fi'nish by means of a centerless grinding operation. Piston engaging surface 14 is held to an accurate diameter dimension and provided with an extremely smooth finish by means of internal grinding and honing of the surface. Thus a very close relationship (sliding fit) is provided between sliding surface 16A and piston engaging surface 14. Such a relationship is so close that air under normal pressure cannot be forced between the two surfaces. It is the shape of piston 16 including the sliding surface 16A and the neck portion which permits the accurate and inexpensive manufacturing procedure and the air tight relationship with the piston chamber. Obviously, such an air tight relationship when associated with a fluid tight packing such as packing 21, will withstand higher fluid operating pressures and therefore a more forceful work stroke of piston chamber 12 because the packing 21 is reenforced with an air tight relationship between the surfaces which are to be made fluid tight. 7 7

Referring to the modified form illustrated in FIGURE 4, piston chamber, generally indicated by reference character 11A, consists of a cylindrical side wall 12A having a base 13A which closes one end thereof; and an outwardly extending lip 9A. Internally, the cylinder or piston chamber 11A is provided with a piston engaging surface 14A and a fluid engaging work area 15A. A pipe threaded tapped orifice 7 is provided in side wall 12A for the purpose of admitting fluid under pressure to piston chamber 11A. Tapped orifice 7 has its bottom edge parallel with fluid engaging work area 15A.

A piston 16A is provided externally with a sliding surface 6A having a circular groove 18A on one end and a neck portion 19A which terminates the other end. A tapered shoulder 20A is formed between sliding surface 6A and neck portion 19A. Piston 16A is provided with a bottom which is recessed at 4. Recess 4 is in alignment with tapped orifice 7 so that fluid under pressure passing through tapped orifice 7 may enter the recess 4 and act on the fluid engaging work area 15A exposed by recess 4 when piston 16A and piston chamber 11A are in initial or work starting stroke position as illustrated in FIGURE 4.

A packing 21A is provided in circular groove 18A for purposes previously described in the form illustrated in FIGURES 1, 2 and 3.

A housing consisting of a cylindrical side wall 23A is provided with a cover 24A on one end and an outwardly extending flange 25A on the other end. A chamber 26A is formed between side wall 23A and cover 24A. Cover 24A is provided with an axial orifice 27A. Outwardly extending flange 25A is provided with bolt holes 28A, 29A.

A thrust plate 30A is provided with tapped holes 31A, 32A and a bore 36A having an annular recess 37A. Bolts 33A, 34A, passing through bolt holes 28A, 29A, respectively, secure outwardly extending flange 25A to thrust plate 30A through tapped holes 31A, 32A, respectively.

The modified form illustrated in FIGURE 4 is assembled as previously described for the form illustrated in FIGURES l, 2 and 3.

The second modified form illustrated in FIGURE 5 diflers from the form illustrated in FIGURE 4 in that the tapped orifice 7B is located in base 133 instead of cylindrical side wall 12B. The recess 4B is located in bottom 5B in alignment with tapped orifice 7B so that fluid under pressure entering tapped orifice 7B may enter recess 4B and act on fluid engaging work area 15B of piston chamber 11B to cause relative movement between piston chamber 11B and piston 16B. In other respects, the form illustrated in FIGURE 5 is similar to the form illustrated in FIGURE 4. i

The area of recesses 4 and 4B must combine with the force of the fluid pressure to overcome the initial tension of springs 40A or 40B, respectively.

Having shown and described a preferred embodiment of the present invention, by way of example, it should be realized that structural changes could be made and other examples given without departing from either the spirit or scope of this invention.

What I claim is:

l. A hydraulic cylinder comprising a thrust plate having a bore provided with a tapered annular recess, a housing consisting of a cylindrical side wall provided with a cover on one end and an outwardly extending flange on the other end, an axial orifice in said cover, means to secure said outwardly extending flange to said thrust plate, a piston provided with a sliding surface, a reduced neck portion, a tapered shoulder formed between said sliding surface and said reduced neck portion, said tapered shoulder mating with said tapered annular recess, said reduced neck portion projecting into said bore, a piston chamber consisting of a cylindrical side wall having a base on one end and an outwardly extending lip on the other end, a piston engaging surface formed internally of said cylindrical side wall and a fluid engaging work area formed internally of said base, resilient means interposed between said outwardly extending lip and said outwardly extending flange, and means to provide a source of fluid under pressure between said piston and said fluid engaging work area, whereby fluid under pressure engaging said fluid engaging work area moves said piston chamber in a work stroke relative to said piston and against the force of said resilient means.

2. A hydraulic cylinder comprising a thrust plate having a bore provided with a tapered annular recess, a housing consisting of a cylindrical side wall provided with a cover on one end and an outwardly extending flange on the other end, an axial orifice in said cover, means to secure said outwardly extending flange to said thrust plate, a piston provided with an axial orifice, externally said piston consists of a sliding surface and a reduced neck portion with a tapered shoulder formed between said sliding surface and said reduced neck portion, said tapered shoulder mating with said tapered annular recess with said reduced neck portion located in said bore, a piston chamber consisting of a cylindrical side wall having a base on one end and an outwardly extending lip on the other end, a piston engaging surface formed internally of said cylindrical side wall and a fluid engaging work area formed internally of said base, and resilient means interposed between said outwardly extending lip and said outwardly extending flange whereby fluid under pressure passing through said axial orifice to engage said fluid engaging work area moves said piston chamber in a work stroke relative to said piston and against the force of said resilient means.

3. A hydraulic cylinder comprising a thrust plate having a bore provided with a tapered annular recess, a housing consisting of a cylindrical side wall provided with a cover on one end and an outwardly extending flange on the other end, an axial orifice in said cover, means to secure said outwardly extending flange to said thrust plate, a piston provided with an axial orifice, externally said piston consists of a sliding surface, a reduced neck portion, a tapered shoulder formed between said sliding surface and said reduced neck portion and a circular groove, said tapered shoulder mating with said tapered annular recess with said reduced neck portion projecting into said bore, a piston chamber consisting of a cylindrical side wall having a base on one end and an outwardly extending lip on the other end, a piston engaging surface formed internally of said cylindrical side Wall and a fluid engaging work area formed internally of said base, packing provided in said circular groove, and a coil spring interposed between said outwardly extending lip and said outwardly extending flange whereby said fluid under pressure passing through said axial orifice to engage said fluid engaging work area moves said piston chamber in a work stroke relative to said piston and against the force of said coil spring, said packing form- 5 ing a fluid tight seal between said sliding surface and said piston engaging surface.

4. A hydraulic cylinder comprising a thrust plate having a bore provided with a tapered annular recess, a housing consisting of a cylindrical side wall provided with a cover on one end and an outwardly extending flange on the other end, an axial orifice in said cover, means to secure said outwardly extending flange to said thrust plate, a piston provided with an axial orifice, externally said piston consists of a sliding surface and a reduced neck portion with a tapered shoulder formed between said sliding surface and said reduced neck portion, said tapered shoulder mating with said tapered annular recess with said reduced neck portion located in said bore, a piston chamber consisting of a cylindrical side wall having a base on one end and an outwardly extending lip on the other end, a piston engaging surface formed internally of said cylindrical side wall and a fluid engaging work area formed internally of said base, and resilient means interposed between said outwardly extending lip and said outwardly extending flange whereby fluid under pressure passing through said axial orifice to engage said fluid engaging work area moves said piston chamber in a work stroke relative to said piston and against the force of said resilient means, said sliding surface and said piston engaging surface forming an air tight seal, said tapered annular recess and said tapered shoulder forming a means to centrally locate said neck portion in relation to said bore.

5. A hydraulic cylinder comprising a thrust plate having a bore provided with a tapered annular recess, a housing consisting of a cylindrical side wall provided with a cover on one end and an outwardly extending flange on the other end, an axial orifice in said cover, means to secure said outwardly extending flange to said thrust plate, a piston provided with a sliding surface, a reduced neck portion, a tapered shoulder formed between said sliding surface and said reduced neck portion, and a bottom, a recess in said bottom, said tapered shoulder mating with said tapered annular recess, said reduced neck portion projecting into said bore, a piston chamber consisting of a cylindrical side wall having a base on one end and an outwardly extending lip on the other end, a piston engaging surface formed internally of said cylindrical side wall, a fluid engaging work area formed internally of said base, resilient means interposed between said outwardly extending lip and said outwardly extending flange means in said piston chamber to provide a source of fluid under pressure between the recess in said bottom and said fluid engaging work area, whereby fluid under pressure engaging said fluid engaging work area moves said piston chamber in a work stroke relative to said bottom and against the force of said resilient means.

References Cited in the file of this patent UNITED STATES PATENTS 1,875,095 Milan Aug. 30, 1932 2,256,028 Jardine et al Sept. 16, 1941 2,467,629 ONeill Apr. 29, 1949

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