US2582512A - Multispeed and multistroke fluidpressure apparatus - Google Patents

Description

Jan- 15, 1952 H. M. STUELAND MULTISPEED AND MULTISTROKE FLUID PRESSURE APPARATUS Filed June '7, 1948 R. m m W MN Om .v .v Q mw @N Lw.. it-: mi G. N n l -o www rw.- l HL N w www# om mm oN um on M4N Nm .vm mm om .wm mm Y /Hwms n W www/J mm /W .www iw Qq @n w/ HAROLD 'M S TUELA/VD Y r9.1 fl! W A TTUPNE YS Patented `ian. 15,

u Nl TE D s TAT-Es 12Areu oFF los 2,582,512 MULTISPEED AND MULTIsTRokE-'Fwin- PRESSURE APPARATUS Harold M. stuelananast Moline; 1u., 'assig'nr'to Deere & Company, Molineglll., a corporationfof l Illinois Application Janet, 1948,v serial ``1-"5.':%1',4'58

6 Claims.

. This invention relates to a multi-speed and multi-stroke fluid-pressure apparatus. More particularly,'the invention relates to such apparatus as adapted in form to a pair of fluid-pressure cylinders in which one has greater capacity but .lift a quantity of material is substantially greater than the effort required to raise the quantity of material at a subsequent stage in the operation. In someinstances, the problem has been eliminated by mechanical means providing linkage giving an increased mechanical advantage at the beginning of the digging and lifting operation.

Inasmuch as 'it has become accepted practice to utilize fluid-pressure cylinders as the lifting means in such apparatus, it is desirable that the iluid cylinders be constructed so that they are capable of securing the same advantages as fmechanical arrangements already known.

Accordingly, it is a primary object of the inventionto provide a multi-speed and multi-stroke huid-pressure apparatus for the purpose referred to. It is another object of the invention to adapt such apparatus to use in situations other than those involving the specific application referred to. It is a further important object of the invention to provide such apparatus in the form of la pair of cylinders arranged in coaxial end-toend relationship to provide a compact extensible and retractable unit in which one cylinder has 'a larger bore and shorter stroke than the other. Still further, itis a feature 'of the invention to utilize fluid-pressure means for the purpose of supplying fluid pressure to the cylinder having the 'larger bore and subsequently applying fluid pressure to the cylinder having the smaller bore, whereby the operation is accomplished in the proper sequence; that is to say, using the more powerful cylinder rst and the faster cylinder subsequently. l n

It is an object of the invention to provide a pair of cylinders rigidly connected in coaxial en'dto-end relationship with the piston in the cylinder having the larger bore provided with a port normally closed by a portion of the piston in the cylinder having the smaller bore, and to yprovide means for supplying iluid under pressure tothe larger piston whereby both pistons 'move simultaneously Ain 'the lsame direction until the (creo-97) tions; and

iarfger piston is "stopped, after 'which theappi- -cation of fl'ui'd 'pressure will be directedtothe smaller piston'tocontinue the stroke of the smaller. piston in' the "same direction. In "this ffor'mf 'thefmventiom iris afeature to provide arifexpension 'chamber 'communicating with the cylin- .der having the larger" bore,` which "chamber serves become "trappedfin thefsys'tern.. y l v ,n

The foregoing "and other desirable A'obiectsjand important'eatures inherent 'inf yandencomp'assed 'by the invention will 'become "apparent to those .skilled in .the a'rt as'jthej disclosurefof'f'a preferred embodiment of tlieinve'ntion made in the followin'g detail'edfdescrip'tion and accompanying sheet of drawing, in which Y V l Figure 1 is a longitudinal`s'ectional viewdfthe cylinder and piston'assexnbly embodying the invention; ..1 l M Figu`re2'is afrag'mentary sectional view ofja portion of the SftiuctlllievhfofwniniFigllI' V1,' 'the pistons being relatively `ds'ps'edi'n different [illisi- L Figure 3 is an enlarged fragmentary sectional 4view ofthe valve 'meanstlat "controlscommunication between one Ais'ylnderand the 'expansion chamber. i q f The dual-cylinder apparatus comprisesfa hist cylinder l0 and-a second cylinder "20. 'Irh'e. yljinders are, arranged in coaxial Send-"t-e'rii "relationship,-one en d of the .f cylinder AIIJ being externally threaded at Il Vfor s'creW-,threadedfefngagement with an internally threadedportionl of the cylinder` -2 0, this" vrl'eas "Sivg rigidly interconnect the cylinders. The oppostefe'nd of the cylinder AIll is closed at `I"2 'and may be provided with a connecting element [3 lby means of which the assembly may beconnected to either the moving orAv stationary vpart of a load-moving structure of lthe typereferredtoabove, for example. ,The opposite endof the yli'nder 20`iiricl1de's a closure housing v22 Yprovided with Aa passage 'or porezsby'ineans :of which. fluid ,pressuremy be admitted to o1" exhausted from fthe "iteir 'f the ;.cylinder assembly. n y .t l Thecylinder ill carriesfor reciprocation therein a piston member I'4,` andthe cylinder`20 carries for reciprocatioh therein a l'piston nin'eihber M. The piston I4 isprovidedv with a .pistonirod is which extends, axially 'through the cylinder through the piston 24, and through 'anfalpropriin opposition to the connection of the connecting element I3 at the opposite end of the assembly.

The piston 24 is preferably in the form of a flanged cup having its radial Wall provided with an aperture or port I1 which is rabbeted at I8 to provide an annular shoulder or seat I9 (Figure 2). l l,

The pistons are normally positioned as shown in Figure 1 and are moved to the left, first in unison, and then the piston 24 is stopped and the piston I4 continues. The means for accomplishing this result includesl the port I1 and a closure portion 25 which is here shown as being formed integrally with a longitudinal sleeve 26 fixed to the piston rod I5 betweena shoulder 21 on the rod and a collar 28 which abuts the rear face of the piston I4. In the normal position of the parts the portion 25, being circular and conforming to the seat I9 of the port I1 and is exposed to uid pressure entering the interior ofthe cylinder 2] through the passage 23 previously Ireferred to, it being understood that the passage 23 may be connected by any suitable means, such as a conduit 29, to a suitable source of fluid pressure (not shown). Therefore,

`fluid pressure entering through the passage 23 is applied against the fluid-receivable portions of bothpistons I4 and 24, acting through the port I1 against the portion 25 to move both pistons simultaneously in the Vsame direction.

There is provided at the juncture of the cylinders IIJ and 2U, a shoulder 30 which provides a stop against which the leading edge of the piston 24 abuts, this means thus limiting the stroke or travel of the piston 24. After the piston 24 is thus stopped, the continued application of fluid pressure effects continued movement of the piston I4 in the cylinder I0, the closure portion 25 separating from the seat I9 of the port I1 so that the port I1 provides, in effect, a fluid-pressure passage through which uid pressure may act on .thepiston assembly I4.' The cylindersl and I1, closes the port 20 are themselves in fluid-interchange relationship.

The assembly also includes means for the escape or expansion of any uid or vapor that may accumulate in the cylinder 29 between the pistons 24` and I4. This means takes the form of an expansion chamber 3l cormected in communication with 'the interior of the cylinder l2l] by means of a port' 32.` Opening and closing of the port 32 is controlled by a valve, indicated in its entirety by the numeral 33.

The detailed structure of the valve appears best Figure 3, wherein it is shown that the valve 'includes a main body 34 threaded at 35 into the chamber 3l and threaded at 36 into a portion of the cylinder 20 that includes the port 32. The lower portion of the valve body 32 includes a valve seat 31, the communication of which With the chamber port 32 is controlled by a poppet type vValve 38 normally held in open position by a coil spring 39. AThe spring operates between a shoulder 40 on the Valve 38 and a shoulder 4I formed as the result of a counterbore in association with a bore 42 axially through the valve body 34 for 'the purpose of carrying a valve stem 43 formed on and extending upwardly from the head of the valve 38. A stop pin 44 at the upper end of the valve stem 43 engages an upper portion of the valve body 34 to prevent complete escape of the valve 38 downwardly into the -cylinder 26. The valve body is provided with a plurality of Vertical bores or passages 45 communicating the interior of the chamber 3I with the valve seat 31 and 4. consequently communicating the valve chamber with the chamber port 32 and interior of the cylinder 20.

The lower end of the head of the valve 38 is recessed or drilled at 46 and receives an inverted cup-shaped member 41. The member 41 is preferably connected to the valve 38 by means of a press nt in the recess 46. The bottom or circular flange of the member 41 is apertured to provide for the extension therethrough of a detent member 48 which is spring-loaded by a compression spring 49. The detent member 48 is flanged at 50 to prevent escape thereof from the member 41. The chamber 3l may be vented at the top thereof, as at 5I, in any suitable fashion.

vin Figure l, fluidV pressure is introduced through the passage 23 against the fluid-receivable portions of the pistons I4 and 24, the fluid-receivable portion of the piston I4 comprising the circular closure portion 25. Consequently, both pistons I4 and 24 move simultaneously to the left until the piston 24 is stopped by the shoulder 30. Simultaneously with the attainment by the piston 24 of its final position, as shown in dotted lines in Figure l, and in full lines in Figure 2, the valve means 33 operates to disconnect communication between the chamber 3l and cylinder 30. This result is accomplished by means of engagement between the detent 48 and the piston 24, the latter having an annular groove 52 therein in which the detent member 48 seats. The detent means thus provides releasable means for releasably locking the piston 24 against retrograde movement. In addition, the engagement between the piston 24 and detent 48 moves the valve 38 tightly against the seat 31, the comparative loading on the springs 39 and 49 providing for this result.

With the piston 24 stopped and locked as aforesaid, the continued application of fluid pressure against the portion 25 unseats the portion from the seat I9 on the port I1 and the piston I4 continues to the left. In the use of the assembly with a load-moving apparatus of the character referred to above, it will be seen that increased power and slow speed is obtained during that initial portion of the stroke in which the pistons I4 and 24 move in unison; and that increased speed, but less power, is obtained when the piston I4 moves by itself after the piston 24 has stopped. In the particular arrangement shown, the assembly is of the one-way type; that is to say, fluid under pressure is supplied through the passage 23 to move the pistons forcibly as aforesaid, thus contracting the distance between the connecting element I3 and the part to which the free or remote end of the piston rod I5 may be connected. Restoration of the parts to their nor.. mal position is accomplished by exhausting fluid through the passage 23, the pistons returning to their original position as by means of the weight of the load imposed on the assembly. In the case of a power loader, forcible contraction of the assembly will be utilized to raise the shovel to dumping position, after which fluid will be exhausted through the passage 23, and the weight of the shovel in returning to its normal position will effect movement of the pistons I4 and 24 to their original positions.

As previously stated, leakage of fluid past the piston 24 may account for the accumulation of fluid or fluid vapors in the cylinder 20. However, inasmuch as the valve seat 31 is normally uncovered by the valve 38 during movement of the piston 24 to the left, such fluid or fluid vapors may escape into the expansion chamber 2|. Since the piston 24 locks the valve 38 in closed position, continued application of fluid pressure through the passage 23 and port cannot be `Icy-passed into the chamber 3|. Similarly, when the piston I4 is returning to the right from its farthermost position to the left, during which phase of operation it will be exhausting fluid pressure through the passage 23, uid will not enter the chamber 3| but will pass through the port I1 and out through the passage 23. Of course, movement of the piston I4 to the point at which the portion 25 seats again on the seat I9 of the port I1 will not in itself completely exhaust all the iluid in the cylinders; however, when the portion 25 engages the piston 24, the two pistons move as one, and the piston 24 is simultaneously returned to its position at the right hand end of the cylinder 20, exhausting iluid through the passage 23. Any fluid that may remain in the cylinder is between the pistons |4 and 24 and is of a relatively small quantity such that it may be readily transferred to the expansion chamber 3| upon subsequent movement of the piston 24 to the left.

Summary The principal characteristic of the invention is a compact assembly including means for providing a short power stroke and a subsequent speed stroke. It should be understood of course that the proportions of the Various parts may be altered to suit patricular situations in which it is desired to use either assembly. The disclosed form of the invention is obviously susceptible to further modifications and alterations, all of which may be made Without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A dual-cylinder uid motor comprising a pair of coaxial, end-to-end cylinders having their proximate ends open and in iluid-interchange relationship, one of the cylinders having a larger bore than the other, and joint means securing the cylinders together at their open ends, the difference in bores providing at the junction of said open ends an interior annular shoulder; a first piston in the smaller cylinder normally positioned at said shoulder and movable toward and back from the other end of said smaller cylinder; a second piston in the larger cylinder normally positioned in axially spaced relation to said shoulder and movable toward and back from said shoulder; means in the larger cylinder providing a iluid inlet at the side of the second piston remote from said shoulder; means in the second piston providing a fluid port therethrough communicating opposite sides of said second piston; means fixed to the first piston and extending into the larger cylinder and cooperative with the second piston to close said port when both pistons are in said normal positions. said port-closing means presenting a fluid-receivable area to the iluid inlet means to combine with the Huid-receivable area of the second piston, said port-closing means having such external dimensions as to be receivable by the smaller cylinder, whereby uid admitted to the larger cylinder through said inlet means and against the aforesaid combined areas moves both pistons simultaneously until the second piston 'is stopped at the annular shoulder, after which admission of fluid through said inlet means effects continued movement of the first piston and port-closing means; and a piston rod connected to the first piston and extending axially outwardly through one end of the motor.

2. The invention defined in claim 1, further chracterized in that: releasable means is provided adjacent the annular shoulder for retaining the second piston in shoulder-proximate position and against retrograde movement until engaged by the port-closing means upon return movement of the first piston and said port-closing means.

3. The invention dened in claim 1, further characterized in that: the port in the second cylinder is circular and concentric on the cylinder axis, and the port-closing means is circular and complementary to said port and has an outside diameter such that said port-closing means slidably fits the smaller cylinder.

4. The invention dened in claim 1, further characterized in that: the piston rod extends from the larger-cylinder side of the first piston; the port in the second piston is centrally located; the piston rod extends freely therethrough and through the end of the larger cylinder remote from said annular shoulder; and the port-closing means is fixed to the piston rod.

5. The invention defined in claim 1, further characterized in that: fluid-expansion means iS provided adjacent said annular shoulder, including a passage communicating with the larger cylinder; a normally open valve is provided in said passage so that fluid between the pistons may enter said passage as the second piston approaches said shoulder; and means is provided for cooperation between said valve and the second piston for effecting closing of said valve When the second piston reaches the shoulder.

6. The invention deiined in claim 5, further characterized in that: said cooperative means between the valve and second piston includes releasable means for retaining the second piston against retrograde movement until engaged by the port-closing means upon return movement of the rst piston and said port-closing means.

HAROLD M. STUELAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 747,772 Rickman Dec. 22, 1903 834,825 Logan Oct.v 30, 1906 851,277 Clark Apr. 23, 1907 2,451,089 Hunter Oct. 12, 1948 2,464,962 Bent Mar. 22, 1949 2,465,714 Elliott Mar. 29, 1949 2,470,074 Manning May 10, 1949 FOREIGN PATENTS Number Country Date 479,434 France Jan. 4, 1916 530,834 France Oct. 11, 1921

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