US2285476A - Fluid motor - Google Patents

Description

June 9, 1942.

I G. A. WAHLMARK FLUID MOTOR Filed Dec. 20, 1959 2 Sheets-Shet 1 INVENTOR. Uzuz/zar (Z I M i! ATTORNEY.

June 1942- G. A. wAHLMA K FLUID MOTOR Filed Dec 20, 1939 2 Sheets-Sheet 2 TTORNEY.

Patented June 9, 1942 2,285,476 rum) oron Gunnar A. Wahlmark, Rockford, n. Application December 20, 1939, Serial No. 310,137

I 11 Claims.

The invention relates generally to a fluid motor and more. particularly to a fluid .motor operable at a plurality of speedspit beingthe.

general-object of the invention to provide a new and improved multi-speed motor.

. A more particular object of the inventionis to provide a'two-speed fluid motor" of new and. simplified construction and particularly adapted for use with a feed and rapid traverse drive for ma-' chine tools. r Other objects include the provision of a twospeed fluid motor of improved construction capable of producing a high torque at aslow speed for feed purposes, and a high speed for rapid traverse, and enabling the use of a constant displacement wobbler for driving the motor shaft. 1 I

Other objects and advantages will become stitutes a cylinder block and has a thicker por-'- tion 2| formediwith a'plurality of bores 23,

herein nine innumber (see Fig. 2)., disposed 1on gitudinally of the casing and arranged annularly,

about theshaft l2. The casing section 22 is in the form of a port plate and abuts against the headror left hand end (seeFig'. 1) of the'cylinde'rblock and cooperates therewith tocomplete the cylinder block. The port plate 22 is formed with a plurality of recesses 21 largerin 'diameter than the bores26 and registering therewith to complete the headends of the cylinders formed by the bores. ,Opening to each .of the recesses" apparent from the following detailed description taken in connection with the accompanying drawings, in-which:

Fig. 1 is a diametrical sectional view of a-fluid motor embodying the features of the invention and a line diagram of a hydraulic circuitfor the motor. 1

Fig. 2 is a transverse sectional view taken ap- 1 V proximately along the line 2-2 of Fig; 1.

Fig. 3 is a fragmentary and partially sectioned view of the motor in the position shown in Fig. 1; but adjusted for high speed operation.

Although the invention is susceptible of various modifications and alternative constructions, it is disclosed in the drawings and-will hereinafter be described in a preferred embodiment. How ever, it is not intended that the invention is to be limited thereby to the specific constructiondisclosed, but'it is intended to cover all modifications and alternative constructions falling within the" spirit and scope of the invention as defined by the appended claims.

As disclosed herein; the invention is embodied in a two-speed fluid motorwhich comprises generally a casing I within which is housed fluid handling mechanism of the reciprocatory piston type, a rotatably mounted shaft I2, and conversion means l3'for converting the reciprocatory motion of the fluid handling pistons into rotary motion of the. shaft. An inlet passage II and an outlet passage |are formed in one end of the casing I0 and cooperate with suitable ports and fluid handling mechanism, and for discharging a the spentfluid after it has functioned to impart a working stroke to the pistons'of the fluid handling mechanism.

The casing It, as illustrated herein, comprises a plurality of sections 20, 2|, 22,23 and 24 which are secured together to 'form a unitby means of a plurality ofbolts extending through the sections 24, 23, 22 and 2|, and into threaded engagement with the section 20. Section2| con- 21 is a cylinder port 28. which, as best seenlin Fig. 2,-is somewhat elliptical shapa beingi formed by three apertures approximating i the.

shape of anellipse. The cylinderblock 2l, and the port plate 22 are secured together by means of a sleeve 29 inserted through a central bore formed in the cylinder block 2|.1 The sleeve; 23

is at one end threaded into the port plate 22 and at the other end is formed with an annular flange 29'. flangedoes not beardirectlyagainst the end of the portion 2| of the section 2|, but bears against bushings 30 which are inserted one in the rod endof each bore 26, and in turn are formed witha radial flange 30'. I I

As illustrated herein, thefluid handling mechanism. ll comprises a first series of sleeve-like pistons 3| reciprocably mounted in the cylinder bores 28,; and a second series of cylindrical pistons 32 of substantially smaller diameter. These smaller pistons 32 are reciprocable in the sleeve- 50. a valve IE to supply fluid under pressure to the like pistons 3| and are formed as integral but, reducedportions of piston rods 33 which extend slidably through the bushings 30 to be guided thereby.-- Thejuncture of the rod 33 and the piston 32, of course, provides an annular shoulder 34 againstwhich the larger piston 3| bears in order that the piston 3| may impart a power stroke to the rod 33. An annular groove 35 is formed in the reduced portion 32 adjacent the shoulder 34 for a purpose which will become more apparenthereinafter.

The conversion means I3 is herein of thewob ble plate type and has a unique construction-emhancing the effectiveness of that type of conversion means. This conversion means is broad- 1y claimed in my copending-application, Serial No.'349,16,3, filedAugust 1, 1940. Forming the basic part of the conversion means is a wobble plate 38 secured to the shaft l2 by means-of a key 39. At one endthe plate 38 bears. against an annular shoulder 40 formed byan enlarged 7 portion of the shaft l2, while at its otherend it bears against theIinner race 4| of a thrust ball bearing 42, the outer race |3 of whichis mounted in the'right hand end of the portion20 ofthe motor casing, as viewed in Fig. 1., Fl'heouter racei 43, in tum-bears against an outer race N of a ball bearing 45, the inner race .46 of which bears against the inner race ll of the thrust bearing". The outer race of the bearing 45 is limited in its outward movement by an annular shoulder "formed in the portion 2|! the motor casing, while the plate 38 and the innerraces 4| and 46 are firmly retained on the shaft |2 by a nut 48 threaded onto the shaft. A rotary seal RS prevents leakage of fluid outwardly along the shaft l2, and a roller bearing 43 supports the inner end of the shaft.

The wobble plate 38 is, of course; of non-uniform construction and comprises a hub-38' and a radial flange 38" disposed in a plane oblique to the axis of the shaft l2 and having closely adjacent its periphery a race '48 for a set of rollers 50. -An annular member 5| provides the otherrace 52 for the rollers 50. which rollers incidentally have a diameter several times their width in order that there may be a substantially one hundred per cent rolling contact of the rollers 50. The face of the member 5| opposite the race 52 is engaged by the projecting end of the rods 33 and, in order that this engagement between the" rods 33 and the member 5| may be most effective, the ends of the rods 33are-made spacing the section 24 from the port plate 22 so as to form a valve chamber l6. Inlet passage l4 communicates with the outer edge of the valve chamber It by means of a .plurality of arcuate ports 60 (see Fig. 2). Exhau'stpassage.

means of the valve l6 which is adapted to eifect the opening and closing of'the ports and are alternatelyfconnected to the; inner and outer. portions'of the valve chamber. I6 in timed re1a-,

tion with'the reciprocation of the pistons in a mannerobtaining a .maximumperiod ofport conical so that they will have a straight line contact with the face of the ring 5|.

To retain the member 5| inits proper relationship with respect to the'plate 38' and to preload the rollers 50, a ball bearing 54; is provided which has its outer race formed in, 'an annular flange 55 which is integral with the member 5|. The inner race of the bearing 54 is formed in a collar 56 carried by the hub 38' of "the wobble plate and is held against rotation by a pin 51. which projects into a key-way 58 formed longitudinally of the hub 38'. The collar 55 is retained in its position on the wobble plate by means of a split ring 59 retained by fltting into an annular groove formed in the hub of the wobble plate for that purpose. It is to be noted that, with this construction, the rollers 50 act on the. outermost portion of the wobble plate 38,

opening,'and"rapid opening and closing of the ports. The valve 16 iscircular in form and is mounted by means of aball bearing 53 on a stud 6| formed eccentrically (see Fig; 2); on the inner end of the shaft l2 and projecting into the space between the port plate 22 and the section.

The faces of .the valve [5 areground so asto have .a fluid-tight sliding fltwith: the adjacent cylinder ports 28 open in whole or in part therewhile the engagement of the rods 33 'with the r It will be recognized that the conversion to. The rim 65 has a radial thickness slightly greater than the width of the port 28, so that in any positionof the valve l6 a plurality of ports 28 are disposed in whole or in part outwardly of the valve l6 so as to communicate with the ,peripheral'portion of the valve chamber it which is supplied by the inlet ports. Thus the-rim 65 of the valve, during; rotation of- .the

annular member 5|, is applicable to hydraulic V devices of this general design, whether they be operated as motors or as pumping mechanisms. In the present instance, the pistons 3| and the pistons 32'operate jointly and simultaneously to efiect a drive of the shaft l2 at alow speed these results will no'w be shaft I2 and the simultaneous orbital movement of the valve, connects-the cylinder ports 28 with the inlet ports 60 during the intake strokes of the pistons, and connects the cylinderports 28 with the outlet ports- 62 during the exhaust strokes of the pistons. Furthermore, when :a piston is at one end or the other of its stroke, the rim 65 closes the corresponding cylinder port 28. In the operation of the valve, the movement of therim 65 with respect to the cylinderports 28 is such that the ports are opened and closed The passage ll, the passage l5 and the valve very rapidly because the eccentric stud 5| is then moving directly toward or away from the particular cylinder port.

As previously stated, the shaft l2 will be driven I at its low speed by the joint operation of'the pistons and 32, while the shaftwill be driven at its, high speed by the sole, operation of the pistons '32. Power strokes are impartedto the pistons by the, fluid under pressure admitted through the cylinder. ports 28,5and theyare moved through their return strokes by the wobble plate 38.

In order that the pistons may operate-independently of the pistons 3|, provision is made to admit the working fluid to the rod end of the cylinders 28. To that end, the portion"2l; that is, the cylinder block, is formed with an annular groove I communicating with each of the cylinders 26 just inwardly of the sleeve 30. This groove in turn is connected by a passage II with a control port I2. Thus, when fluid is supplied:

to the rod end of the cylinders 26 under pressure, the pistons 3| are ,forced and held against the head end of the section 22 where they are held operation is assured because the pressure .fluid' tons 32 and thus because ofthereduced displacei ment of the motor would cause the same to operate at a higher speed. I claim as my invention:

l.- A two-speed fluid motor comprising, in cam bination, a casing, a cylinder therein, an annular piston reciprocable inthe headIend of said cylin-J der, a bushing fixed in the rod end of said cylinder, an elongatedmember having a portion slidable in said bushing and in all positions project supplied through the annular groove I0 is always substantially uniform, while the pressure supplied to the head end of the pistons 3| is intermittent due to the opening and closing of the ports 28 by the valve It.

The fluid supplied to the rod end of the cylinders 26 may be governed in a variety of ways by any suitable means, such as a valve, for effecting the opening and closing of a conduit connected with the control port'l2 and conducting pressure. fluid. In Fig. 1 there has been illustrated a line,

diagram of a hydraulic circuit including this motor and a pump "connected by an intake conduit 15 to a-reservoir I6 and by a conduit 11 to the intake passage N of the motor. A conduit I8 branches off from the conduit 11 and leads 1 to a control valve I9 having one conduit 80 leading therefrom to the port I2 and a return conduit 8| leading to the reservoir I6. The valve I9 may be of any construction, such that at predetermined times or upon predetermined operation pressure fluid from the pump I4 will be supplied to the rod end of the cylinders 26 through the port I2 and connecting passage 1|, while at other times the conduit" is closed and the conduit 80 connected to the return conduit 8|. The circuit is completed by a main return conduit 82 leading from the exhaust\ passage IE to the tank T6. The operation of the moton disclosed herein, when connected in circuit as shown, would be asfollows: If it isassumed that the valve 19 is adjusted to the position shown in Fig. 1, namely, wherein the conduit I8 is blockedand the rod ends of the cylinders are connected to the tank 18, the fluid supplied by the pump I4 would be effective to act upon both the small piston 32, as well as the large annular piston-3|. Because of the increased displacement of the motor under such circums ances, it would operate at low speed with the power of the motor, of

course, correspondingly increased due to the larger area of the combined pistons. To obtain a higher speed of operation for the same displacement .of thepump I4, it is only necessary to rotate the valve 19 ninety degrees in acounter-clockwise direction, as viewed in Fig. l, which would then connect the conduits I8 and the conduit'8ll to supply fluid to the rod ends of the cylinders through the piston II and groove I4 communicating therewith. Thepressure fluid so supplied to the rod end of the cylinders would act upon the piston 3| of each cylinder and during the time that the head end of the cylinder is connected to the discharge port l5 would shift the piston 3| against the plate 22 to the position shown in Fig.3. This wouldexpose the entire rod end area, of the piston 3|, while'rendering a major portion of the head end area of the pising from the rod end of said cylinder to form a1 her endpiston rod, a reduced portion at the; I of said member slidable in saidanriiilarrpiston to form' ja high speed piston, andt afiannular shoulderat the base of the reduced' portionpro viding an abutment through which the nnular; piston may impart a power stroke to said'n'iem her, said member beingcapableflof independent. movement through a power 'strokepa 'rotatably mounted shaft, means for converting the reciprocatory motion of said cylindrical member into rotary motion ofthe shaft, valve means driven by said shaft for controlling the supplyofopera ating fluid to the head end of said cylinder','the' fluid acting on both pistons to effect simultaneous operation thereof and operation'of the motor at a low speed, and a passage for conducting operating fluidto the rod end of the 'cy1inder,i n=

termediate said annular piston andsaid bushing' to balance the fluid acting on the opposite end of saidannular' piston to render the same 'inoperative and effect high speed operation of the motor through said high speed piston my. I -2. A'fluid motor comprising, inrcom bination,

a casing, a cylinder thereingan annular-piston reciprocable in the head end of said cylinderj' a bushing fixed in the rod end oisaid cylinder, an elongated member having a portion slidabl'e" in said bushing and in all positions projecting from the rod end of said cylinder to form a piston rod, a reduced portion at, the other endof said member slidable in said annular piston" to form a high speed piston, and an annular'shoul der at the base of the reduced portion providing an abutment through which the annular pis ton'may impart a power\ stroke tosaid member, said member being capable, of independent movement through a power strcke a rot atably mounted shaft, means'for' converting the resin-'- rocatory motion of said elonga edimemberinto rofi: motion of the shaft, valve'means'driv'en by aidtshaftior controlling the supply of operatin fluid to the head end of said; cylinder, and means to balance the fluid acting; onthefhe'ad' end of said annular piston to render the same inoperative and v ffect high'fspeed operation *of the motorthrough said high speed pistonoiily.

3. A fluid motor comprising, 'in combination, a casing, a cylinder therein, a bushing intherod end of said cylinder, a'cylindrical member having a portion forminga piston rod slidab'l'y mounted in said bushing'and' in all positions projecting through the bushing outwardly of the'cylinder. saidcylindrical'member having a reduced end portion forming a piston and an annular 'shoul' der, an annular member slidably mounted in 'th'e head end' of said cylinder to form' 'a piston and"'-. I

having a bore in which the-first mentioned piston reciprocates, a rotatably mounted shaitprrians ton 3| ineiiective sov that the piston could readily be retained against reciprocation inthe po' sition shown in Fig. 3 by the fluid in the rod end of the cylinder. With the'pistfon 3|. held station ary', thefluid supplied through'theintake port l4 would, of course, act only upon the small pisfor converting the reciprocatory motion of said cylindrical member into rotary motion ofthe shaft, and means for supplying pressure fluid to said cylinder intermediate said bushing and said annular piston to render said first mentioned casing, a first piston reciprocable in said cylinder having a'bore extending longitudinally thereof and opening through both ends-thereof, a second piston only operative for high speed operation of the motor. v i

4. A two-speed fluid motor comprising, in combination, a casing, a plurality of annularly arranged cylinders in said, casing, a rotatably mounted shaftconcentric of said cylinders, valve means driven by'said shaft to control the flour of operating fluid to and from the head end of said cylinders, a' first piston slidably mounted in each cylinder, a second piston slidably mounted in said first piston and exposed to the pressure fluid inthe head end of the cylinder to be jointly reciprocable with saidrflrst pistonvto eflect op- Y eration of the motor at low speed,'means conbination, a casing, a plurality of annularly arranged cylinders in said casing, a rotatablyj mounted shaft concentric of said cylinders, valve means driven by said shaft to control the flow of operating fluid to and from the head end of said cylinders, aflrst and a second piston reciprocable .in each cylinder and each exposed to the operating fluid in the head end of the cylinder, a bushing in the rod end of each cylinder, a piston rod projecting through said bushing and having a fluid-tight sliding fit therewith, said piston working stroke to said rod while permitting said rod to move through aworking stroke independently of the other piston, means for converting the reciprocatory motion of saidrods into'rotary motion of said shaft, and means for conducting operating fluid to the rod end of said cylinders to render one of said pistons ineffective and cause operation of the motor at a higher speed.

v6. A two-speed fluid motor comprising, in combination, a casing, a plurality of annularly arranged cylinders in said' casing, a rotatably mounted shaft concentric of said cylinders, valve means driven by said shaft to control the flow of operating fluid to and from the head end of said cylinders a first piston slidably mounted in each cylinder and a second piston slidably mounted in said first piston, both pistons being exposed to the pressure fluid in the head end of said. cylinder to be jointlyacted 'upon by the pressure fluid in the head end of the cylinder to effect, operation oflthemotor at a first speed, a bushing in the rod end of each cylinder, a pisrod having a connection with at least one of" said pistons permitting the piston to impart a,

ton rod projecting through the bushing and having a fluid-tight slidable fl't therewith, one of saidpistons being integral with said piston rod, theother of said pistons being adapted to impart a working stroke tosaid piston rod and said rod being movable through a working stroke inde pendently of said last mentioned piston, means for converting the reciprocatory motion of said piston rods into rotary motion of said shaft, and means for conductingoperating fluid to the rod ends of the cylinders to counterbalance the eifect of the operating fluid on the pistons with respect to which the piston rods have independent movement.

7. in? a fluid motor, a casing, a cylinder in said piston reciprocable in the bore of said first piston, a piston rod adapted to have a working" stroke imparted thereto by both of said pistons and to be movable through 'a working stroke independently of at least one of said pistons, ,a

port through which operating fluid may be supplied to the head end of saidcylinder, and a port through which operating fluid may be, simultaneously supplied to the rod end of said cylinder to hold one of the pistons against reciprocation.

8. In a fluid motor',-a' casing, a cylinder in said of and opening through both ends thereof,a sec- 0nd piston reciprocable in the-bore of said first piston, a piston rod adapted to-have a working stroke imparted thereto by -bothr said pistons and to be movable through a workingstroke independently of at least one of said pistons, a port through which operating fluid may be supplied to the head endof 'saidcylinder, and means selectively operable for applying fluid under pressure simultaneously against both ends of the piston with respect to which said piston rod has an independent working stroke thereby holding-I said piston against reciprocation;

9. A two-speed fluidmotor comprising, in combination, a casing, a pluralityof annularlyarranged cylinders in said casing, a rotatably mounted shaft concentric of said-cylinders, valve means driven by said shaft to control the flow of operating fluid to and from the head end of said cylinders, a first and a second piston re-" ciprocable in each cylinder and each exposed to the operating fluid in the head end of the cylinder, means for converting the reciprocatory motion of said pistons into rotary motionof said shaft, andmearis for conducting operating fluid combination, a casing,aplurality of annularly arranged cylinders in said casing, a rotatably mounted shaft concentric-of said cylinders, valve means driven by said shaft to control the flow of operating fluid to and from the head end of said cylinders, a first and a second'piston reciprocable in each cylinder and each exposed to the operat ing fluid inthe head end of the cylinder, rneans for converting the reciprocatory motion of said pistons into rotary motion of said shaft, and fluid means for rendering'one of said pistons ineffective to cause operation of the motorfata higher I speed.

11. A two-speed fluid motor" cornprisingf'in'v combination, a casing,a plurality of cylinders in said casing, a rotatably 'mounted' shaft, valve means driven" by said shaft to control the 'flowof operating fluid to and from the head' end or said cyl nders, a first and a second set of pis-- tons reciprocable in :the cylinders each piston exposed to the operating fluid in the head end of the cylinders, means for converting the reciprocatory. motion of said pistons into rotary motion of said shaft, and'means for simultaneously applying operatingfluid to both'endso'f the pistons of one set to render'that setlof pistons ineffective and cause operation of the motor at a higher speed. 7

' "GUNNAR A. wsmmnx,

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