US3314367A - Hydraulic transformer - Google Patents

Description

Filed Sept. 20, 1965 w @v QR INVENTOR. 62 5205 fl [/VE/F April 18, 1967 c. B LIVERS 3,314,367

v HYDRAULIC TRANSFORMER Filed Sept. 20, 1965 v 2 Sheets-Sheet 2 v INVENTOR. B 614E405 31/1 0519 gwi a United States Patent "ice 3,314,367 HYDRAULIC TRANSFORMER Carlos B. Livers, Studio City, Calif., assignor to Crane Co., Burbank, Calif., a corporation of Illinois Filed Sept. 20, 1965, Ser. No. 488,679 Claims. (Cl. 103-49) This invention relates to variable displacement pump ing apparatus, and has as its principal object to provide a fluid pumping device of extremely light weight such as to adapt it especially for vehicles wherein weight-saving is of prime consideration.

Toward the attainment of this broad object, the invention provides a fluid pressure transformer apparatus which utilizes one fluid to drive a series of axially-slidable pistons in a positive displacement pump which delivers another fluid to a load (such as one or more hydraulic actuators or servo motors) utilized in controlling the travel of the vehicle or other phases of operation of the environmental apparatus in which my hydraulic transformer may be utilized.

In a more specific application, the apparatus is adapted to utilize a fluid under pressure at one level to drive a pump delivering a fluid at a different pressure level to the load.

In a particular application, the invention utilizes fuel at its normal pressure (the relatively low pressure level of the apparatus) to sequentially move a plurality of relatively large pistons of a piston motor, and the movements of these pistons are transmitted to a corresponding series of relatively small pistons which deliver the relatively high pressure hydraulic fluid (e.g. oil) output of the transformer which is utilized to act upon the load. All systems of this general type involve a hydraulic motor driving a hydraulic pump. To do this in a literal sense results in a bulky inefficient package. It is therefore important to directly couple the motor pistons to the pump pistons avoiding the conversion of energy into bearings, rotating shafts, seals, etc. In previous proposals the art has used a rotating valve driven by a small separate hydraulic motor to produce the necessary reciprocating movement of the pistons. The present invention differs in that the pistons are also valves. The mechanism is automatic and continuous motion is achieved without the aid of separate motor-driven valves. The pistons on the fuel side operate as a hydraulic motor and the pistons on the oil side operate as a hydraulic pump. The forces generated by the fuel pistons are transmitted directly to the oil pumping pistons. A Wobble-motion connector, tying the piston sets together, is used to control stroke and timing but consumes no power other than very minor bearing friction. Since the pump operates in the exact reverse of the motor, the motor will be described more in detail than the pump.

The principal object of the invention is to provide a hydraulic transformer of maximum simplicity and minimum Weight. In the transformer of this invention, it is possible to avoid the necessity for using conventional rotating cylinder blocks, heavy thrust bearings and shaft seals; normal problems of efliciency, Weight, size and complexity are essentially eliminated; and an extremely eflicient, simple and lightweight construction is achieved. While the invention was initially designed for use as a pressure booster or intensifier, in its broad aspects it is also applicable to a pressure de-intensifier and flow booster in which pistons of smaller diameter are acted upon by drive fluid to drive respective pistons of larger diameter which generate lower pressure and higher flow in the pump fluid than that of the driving fluid.

The invention also-has application as a system isolator where it is desired to transfer power from one system 3,314,367 Patented Apr. 18, 1967 to another without fluid mixing. In such applications the ratio of displacement is usually one to one and the unit is completely reversible and capable of transmitting power but not fluid in either direction. It also may be used to separate different fluids and/0r gasses.

Additional objects of the invention are to provide a hyddraulic transformer;

(l) Wherein precessive stroking operation of the pistons is controlled by a wobble-motion control coupling between pistons;

(2) Wherein very little power is consumed by this control coupling;

(3) Wherein the coupling has a number of functions, including:

(a) controlling the stroke (b) controlling valve timing (0) returning the motor pistons on their exhaust strokes and sectioning being as indicated by line 2-2 of FIG. 1

((1) moving the pump pistons on their suction strokes.

(4) Minimizing internal leakage;

(5) Avoiding the necessity for piston-return springs or springs for any other purpose;

(6) Avoiding the necessity for moving seals and requiring only a limited number of static seals;

(7) Adaptable for the use of steel for almost all of its parts;

(8) Requiring hardening only in the wear surfaces of its cylinder bores, and utilizing tough, fracture-resistant metal throughout its housing structure;

(9) Of high degree of simplicity in the construction, arrangement and operation of its parts;

10) A minimum of four pistons may be used in both the motor and the pump portions and the number may be increased in any multiple of four.

Other objects and advantages will become apparent in the ensuing specification and appended drawing in which: FIG. 1 is an axial sectional view of the transformer;

FIG. 2 is an end view, partially in section of the transformer;

FIG. 3 is a schematic piston stroking and flow diagram of the basic four piston unit; and

FIGS. 4 and 5 are fragmentary cross-sectional views taken on lines 4-4 and 5-5 respectively.

General description In the drawings I have shown, as an example of one form in which the invention may be embodied, a hydnaulic pressure booster comprising, in general, a motor unit A and an axially opposed pump unit B, each comprising an annular array of cylinders and a corresponding array of pistons therein. The cylinders and pistons of motor unit A are of relatively large diameter, for response to relatively low fuel pressure, and the cylinders and pistons of pump unit B are of relatively small diameter, for developing relatively high pressure in the hydraulic fluid (e.g. oil) which is pumped thereby.

A wobble-motion connector C couples the pair of pistons of each set to one another, and couples the complete annular array of piston sets together for controlling the stroking of the pistons and timing of the valves in a precessive relation to one another such that each piston, in its stroking position, will lead the immediately following piston by a percentage of the complete stroking cycle, equivalent to the fraction of a complete revolution represented -by the angular spacing between adjacent pistons, where they are equi-angularly spaced, as in the preferred form of the invention.

The basic motor (or pump) unit of the invention requires four pistons, each piston being in the form of a spool valve. Circumferential manifolds appropriately its mid-stroke position is not only switching from pressure to return, or the reverse as required, but it is also moving at its greatest speed so as to provide very napid valve action. This takes place at a time when the neighboring piston being controlled is at top or bottom dead center where its speed is virtually zero. This ideal condition allows the valves to be made with a small but positive overlap thus providing highly desirable low leakage conditions. Each piston receives driving pressure during its full power stroke and similarly is connected to the return system during its retracting stroke. The number of pie tons .used may be increased in multiples of four. The invention contemplates an optimum of twelve pistons in both the motor and the pump, all pistons having the same stroke. This result is attained simply by pivotally connecting the pistons to the connector C on pivot centers disposed in a common plane.

The motor cylinders are bored in an integral motor cylinder block which is generally in the form of a cylindrical sleeve having a wall thickness suificient to encompass the cylinders. Each cylinder therein, tho-ugh bored as a single unit, is functionally divided into two sections which will hereinafter be referred to respectively as a reaction cylinder 11, in which fuel will react against the forward end of a motor reaction piston land 12, and a valve cylinder 13, in which a spool valve element (composed of a valve piston land 14, the rear end of reaction piston land 12, and an integral connecting stem is axially slidable. correspondingly, each cylinder of the pump unit- B, formed in a pump housing section 110, is divided into a reaction cylinder 111 in which a pump reaction piston land 112 reacts against hydraulic liquid therein with a pumping effect, and a valve cylinder 1:13 in which a spool valve element 112, 114,115 is axially slidable. The motor 'andpump cylinders are arranged in sets each comprising a cylinder 11, a cylinder 13, a cylinder 113 and a cylinder 1 11, all aligned on a common stroking axis; aligned in sets each comprising a motor piston having lands 12 and 14 and a pump piston having lands 112 and 114. The pistons further include respective integral heads 16, 116 of zonal-spherical form integrally joined to respective lands 14, 114 by reduced necks 17, 117 and correspondingly, the pistons are axially-.

having'fiat ends abutted one against the other, in radiallyhousing jacket 18 which includes an extended portion sur-' rounding the connector C and functioning as a crank case within which the connector is rotated and lubricated.

Motor block 10 is provided at its outer end with a coaxial inlet fitting 19 providing an inlet port for fuel. Fitting 19 is mounted in an'inlet throat 211 which is defined by the cylindrical inner wall of block 16 and leads to a manifold 23 through which the fuel is distributed to the respective valve cylinders 13. Manifold 23 is formedas a deep, narrow, annular radial slot in motor block 10 intersected by the cylinders 11 and the pistons 12 which pass theret-hrough. The motor block is reinforced by a cylindrical collar 21 secured in throat 20 in a position bridging across the opening between throat 20 and manifold 23, collar 21 having a plurality of ports 22. The manifold 23 functions as a common inlet port 24 for the respective cylinders and defines a boundary between the valve cylinders 13 and the reaction cylinders 11,

at the outer ends' of the valve cylinders. At the inner ends of the valve cylinders 13 is a similar annular valve outlet port 25 of deep annular slot form, communicating with a combined crank-case and outlet chamber 27 which is defined withinthe crank case portion of housing jacket 18 and which in turn communicates with a motor outlet port 28 defined by a lateral fitting 29 in one side of crank case jacket 18.

Extensions of valve cylinders 13 beyond the valve outlet ports 25 provide integral sleeve bearings 30 in which the piston lands 14 are slidably supported.

Each of the valve cylinders 13 is provided in its outer side with a transfer port 35 communicating with one end of a respective transfer passage 36 the other end of which communicates, through a second transfer port 37, with an associated reaction cylinder 11 circumferentially displaced from the respective valve cylinder 13. As an optimum arrangement for solving the geometry of the apparatus, the associated cylinders are angularly displaced apart. This makes it possible to build a transformer with four, eight, twelve (or larger multiples of four) cylinderpiston sets. The specific arrangement shown in the drawing utilizes twelve sets, there being three independent groups of associated sets.

It may now be noted that, for each piston-cylinder set, a valve chamber 33 is defined within the respective valve cylinder 13 between the respective piston lands 12, 14 which, connected by the respective stem 15, constitutes a slida'ble' spool valve element as previously stated. The chamber 38 will shift axially within the respective cylinder 13 in accordance with the piston stroke, and at a retracted piston position (e.g. as shown at the bottom of FIG. 1) the chamber 38 will communicate with the valve inlet port 24 while the corresponding valve outlet port 25 is closed by the respective piston land 14, whereby inlet flow entering through the port 20 and passing through a respective manifold port 22 will be directed through the respective chamber 38 and its transfer port 35 into a transfer passage 36 which will lead the flow to a respective reaction cylinder 11, in which the fuel will react against the outer end of a piston land 12 to commence to drive the piston set in a power stroke. The power stroke (just completed) of the piston at the top of FIG. 1 is indicated by arrow 41 At the same time, a diametrically opposed piston set (e.g. the one shown at the top of FIG. 1) will commence to move in a retracting or return stroke. The return stroke (just completed) of the piston at the bottom of FIG. 1, is indicated by arrow 41. 'Such return movement is transmitted to the pistons by the connector C, and this will result in the discharge of fuel from the reaction cylinder" 11 of the retracting set in a return flow through its transfer port 37, its respective transfer passage 36, and its. respective transfer port 35 into'the valve chamber 38 of an advancing piston set which communicates with the respective valve outlet 25, the crank case chamber 27 and the motor outlet port 28. The indicated return flow from the cylinder in the background of FIG. 1, through the valve chamber atthe top of FIG. 1, is just completed and at the cutoff or switching stage; These flows are indicated by the lines of arrows in FIG. 1, the full line and dotted-line arrows indicating flowsin or behind the cross-sectional plane of this figure, and the dot'dash arrows indicating flow in front of the plane of FIG. 1. It should be noted that the port 37 shown in FIG. 1 lies at the back side of the motor as viewed in FIG. 1. The transfer passage 36 leading upwardly from the lower side of FIG. 1 is shown' in dot-dash lines to indicate the fact that this passage lies in front of the plane of FIG. 1 and leads to a'port 37 diametrically across from the port 37 as 'seenin FIG. 1.

For a more complete understanding of the precessive stroking and timing of the pistonsand valves, it may be noted at this point that the valving action in each valve cylinder 13 commences at a point where the piston is at a substantial distance from the end of itsstroke, and that the switch from pressure flow to return flow occurs when a piston is at midst-roke and at maximum velocity. Referring now to the motor piston at the bottom of FIG. 1, it will be seen that its valving action in the transfer of fuel at inlet pressure through valve inlet port 24, valve chamber 38, port 35 and the transfer passage 36 extending in front of the plane of the drawing, began at the midpoint of the return stroke 41 of the respective piston, the port 24 being rapidly opened to permit the flow to commence rapidly, and the flow continuing while the piston has reached the end of its return stroke and has commenced a power stroke 40, in response to inlet fluid which commences to enter its reaction cylinder 11 at the point where its stroke is reversed. The valving action of this piston, in transferring inlet fluid to the valve port 37 above the plane of FIG. 1 will continue as the piston moves back to midstroke, at which point the inlet valve port will be closed and the outlet valve port 26 will commence to open, thus switching the flow through the valve chamber 38 associated with this piston. Referring now to the port 37 and its associated reaction cylinder and piston in front of the plane of FIG. 1 to which the incoming fuel has been directed by the valving action just referred to, and which is disposed at 90 between the two cylinder-piston sets seen in FIG. 1, it will be apparent that this piston at the 90 position will be at the midpoint of its stroke when the valving piston (at the bottom of FIG. 1) has completed its return stroke and commences to reverse as shown, and that the front 90 piston now referred to will have been at the end of its retracting stroke and commencing its power stroke at the point where the valving piston at the bottom of FIG. 1 has reached its mid-position and commenced to open its associated valve inlet port 24 and to correspondingly start the transfer of pressure fluid to the reaction chamber 11 of the front 90 position piston. During the half cycle of movement of the valving piston in which it completes the last half of its retracting stroke and the first half of its power stroke, the power-stroking piston will have completed its power stroke from-its fully retracted position to its fully extended position corresponding tothat of the upper piston of FIG. 1.

At the same time, the cylinder-piston set associated with the transfer port 37 indicated in the background in FIG. 1, will have been at the end of its power stroke when the piston seen at the top of FIG. 1 was at its midstroke position in which it commenced to open its associated valve outlet port 25, and the rapid mid-stroke movement of this upper piston has quickly opened the outlet port 25 to provide for rapid escape of the fuel from the 90 background cylinder as its respective piston has commenced its retracting stroke under push applied to it by the connector C.

The pump B has an arrangement of transfer passages 136 functioning in the same manner as the transfer passages 36 of the motor but arranged internally of the pump cylinder housing 110 instead of externally, and communicating with a plurality of valve inlet ports 123 and transfer ports 135 and 137 corresponding functionally to the ports 23, 35 and 37 of the motor unit.

Each of the transfer passages 136 communicates at one end, through a transfer port 135, with a respective valve cylinder 113 and at its other end, through a transfer port 137 with a reaction cylinder 117 angularly offset 90 from the respective valve cylinder 11-3.

Hydraulic oil enters the pump through an inlet port 120, travels to the valve inlet ports 123 through a central passage defined by a throat 146, and passes through a port 123 when a pump piston is in a retracted position as shown at the bottom of FIG. 1. Thence it passes through the transfer port 135 into a transfer passage through which it travels axially and circumferentially from the valve chamber 113 through which the fluid is being passed. The retracting stroke of the piston in the reaction cylinder to which the fluid is thus transferred will continue until its cylinder 111 is filled with fluid. During continued operation a return stroke is delivered to this piston by the connector C, which will force the fluid out of its chamber 111 under relatively high pressure through its associated transfer port 137 in a return flow through an associated transfer passage 136 to a valve chamber 113 in which the spool valve 112, 114, 115 is in a position to direct this pressurized flow through its respective valve outlet port into a discharge manifold 118 and thence through a discharge port 128, thus providing a discharge.

The most efiicient arrangement of the transfer passages 36 is one in which they extend helically side by side, sep-' arated by helical partitioning fins 45 which preferably are formed integrally with the cylindrical periphery of the motor housing 10. Other configurations for extending the passages 36 axially and circumferentially can be utilized, especially where a smaller number of cylinder-piston sets are employed, but the optimum configuration for a full twelve sets is helical as disclosed.

The cylindrical jacket 18 encircles and is fitted, secured and sealed to the peripheral surfaces of fins 45 by any suitable means, such as brazing. The jacket 18 provides a common peripheral closure for all of the passages 36. At the outer end of the motor housing, the fins 45 are merged in an end wall 47 in the form of a flat ring disposed in a plane normal to the major axis of the transformer, and the inner ends of the fins 45 are similarly merged in an offset wall 48 in the form of a ring.

Passages 136 are defined between helical fins 145 formed externally on the cylindrical inlet throat 146 which has at its outer end the inlet port 120. The peripheral surfaces of fins 145 are fitted, secured and sealed to a cylindrical inner wall of the pump cylinder housing 110, in which there are provided the valve ports 123, and 137. The ports 123 are of annular channel form, concentrically encircling the valve cylinders 113 at the inner ends thereof. Respective valve outlet ports 125, likewise of annular channel form encircling the outer ends of valve cylinders 113, are in communication with the pump outlet manifold 11-8 encircling the outer end of the pump cylinder housing 110 and discharging through the outlet port 128.

At their outer ends, fins are merged with a fiat annular end wall 147 and at their inner ends they are merged with an annular offset wall 148 in the form of a fiat ring normal to the major axis of the transformer. From the periphery of offset wall 148 a cylindrical collar extends to an annular radially inwardly extending web 156 from which a bearing boss 157 projects axially into the throat 146. Valve inlet ports 123 are extended through the peripheral collar 155.

The outer ends of reaction cylinders 11 and 111 are closed by annular cap rings 60, 160 and are sealed by O-rings 61, 161 compressed between the cap rings 60, 160, the walls of cylinders 11, 111 and the heads of threaded studs 62, 162 which extend through apertures in the cap rings 60, 160 and are drawn tight by nuts 63, 163.

The projecting portion of motor-crank case jacket 18 terminates in an inwardly offset neck 65 which is fitted around a flanged end portion 66 of the pump cylinder block 110 and sealed thereto by an O-ring 67 disposed in an annular groove in the end portion 66.

While the construction and operation of the motor and the pump have been described in full detail herein for a full understanding of the construction and operation of the complete apparatus, the pump per se is similar in construction and operation to the fluid motor of my prior Patent No. 2,994,306, issued Aug. 1, 1961, which discloses such a motor with its pistons in driving engagement with a wobble-plate which drives a crank shaft from which rotary power is delivered. Also, is may be noted that an arrangement wherein free-floating pistons of a motor are paired with aligned floating pistons of a pump for driving the same, is disclosed in the prior application of Jorge Alfredo Morando, Ser. No. 286,620, filed June 10, 1963 for Hydraulic Transformer, wherein the pistons are spring-loaded for return movement, and

wherein a separate motor driven rotary valve is provided for timing and controlling the operation of the pistons. The present invention is an improvement over the hydraulic transformer of that application in that the necessity for the rotary timing valve and its separate driving motor has been eliminated, and in that a Wobbleplate is utilized, not for transmiting power, bu only as a means for retaining the pistons in coupled relation and for transmitting return strokes thereto (when the pistons are not under load). The wobble-plate mechanism will now be described.

Connector C comprises a Wobble-plate 70 having a hub 71 journalled through anti-friction bearings 72 upon respective ends of a skewed crank shaft 73, so that the latter may rotate to accommodate nutating movements of the wobble plate. Crankshaft 73 has respective crank throws 74, 75 with integral trunnions 76, 77. Trunion 76 is journalled in a bearing 78 within a boss 79 on a central partition wall 80 which closes the inner end of motor inlet throat 20 and against which the manifold 21 (a narrow cylindrical ring) is seated. Trunnion 77 is journalled in a bearing 81 which in turn is mounted within the bearing boss 157 of the pump inlet throat 146. The boss 157 and annular Web 156 cooperatively close the inner end of the pump inlet throat 146.

Wobble-plate 70 has an integral rim 85 of channel section, interrupted by radial slots 86 in its periphery, the piston stems 1'7, 117 being snugly embraced in these slots so as to provide coupling connections between the wobbleplate 70 and the pistons, in which there is no substantial circumferential play. Bearing pads 87 are embraced between the walls of rim channel 85, the pads being of ring form, with zonal-spherical bearing recesses in which the correspondingly spherical surfaces of piston head 16, '116 are seated for universally pivotal movement. The pads 87 are slidable radially against the inner .walls of the rim channel 85 as the connector C nutates, thus accommodating limited radial and circumferential shifting movements of the pads and pivotal movements of the piston heads to accommodate'tlie wobble-movement of the connector C.

Reviewing the operation of the apparatus, as fluid onder pressure is delivered into the inlet throat 20' of the motor A, the pistons thereof will execute power strokes as hereinbefore described, in precessive order as illustrated in FIG. 3, and will transmit corresponding power strokes directly to the pistons of pump B through the abutting engagement of piston heads 16, 116 within the embrace of connector C. Movement is simultaneously transmitted to the connector C for controlling the timing and stroking of the pistons in the proper precessive order through the valving operation of the pistons, and for transmitting the return movements to the pistons, but since neither the valving movements nor the return strokes of the pistons are opposed by any load, and none of the load transmitted from the motor to the pump through the abutting pistons is carried by the, connector C, only a negligibly small portion of the transmitted power is utilized in eifecting nutation of the wobble-plate 70 and the valving and return movements of the pistons. The loading of its bearings by the rotating crank shaft 'will likewise be negligible. Thus the invention avoids the conversion of any appreciable amount of energy into bearings, rotating shafts, seals etc. Since each piston in passing through its mid-stroke position is not only switching from pressure to return, or the reverse as required, but is also moving at its greatest speed, very rapid valve :action takes place at a time when the neighboring piston being controlled therebyis at top or bottom dead center where its speed is virtually zero, and is highly efiicient.

The term fluid as used herein is intended to embrace both liquids and gases.

I claim:

1. A hydraulic transformer comprising a motor unit Operable y 0. 15 flu d and an axially-opposedpump unit for pumping another fluid, said units including means defining respective annular arrays of reaction cylinders and valve cylinders; and respective piston sets each including pistons slidable in the respective reaction cylinders and spool valve element slidable in the respective valve cylinders to provide respective flow-control valves; inlet and outlet ports connected to the respective valve chambers in axially-spaced relation; transfer passages each connecting a respective valve cylinder to a respective circumferentially-displaced reaction cylinder; and control means coupling said piston sets for precessive stroking of said pistons such that said valves will operate to connect said transfer passages alternately to said inlet and outlet ports so as to switch from intake to return flow precessively in said reaction cylinders; said annular arrays of cylinders being arranged with each reaction cylinder aligned with a respective valve cylinder and with the cylinders of one array aligned with the cylinders of the other array; said pistons being arranged in opposed, aligned pairs, each pair having abutting ends in the form of heads with universally pivotal bearing surfaces, and having reduced necks connecting said heads -to their respective pistons; said control means comprising a nutating wobble-plate having peripheral socket means, and bearing pads confined in said socket means in universallypivotal, embracing bearing engagement with the abutting heads of respective piston pairs so as to tie the sets of pistons together to transmit return strokes to the valve pistons, with the heads of the respective pairs in pressure-transmitting relation so as to directly transmit pressure from one piston of a pair to the other along the common longitudinal axis of the pair of pistons.

2. A hydraulic transformer comprising axially-opposed motor and pump units including respective housing means having respective annular arrays of motor reaction cylinders, pump cylinders and corresponding valve cylinders, said cylinders being arranged in sets each comprising a motor cylinder, a pump cylinder and a respective valve cylinder aligned on a common axis, each valve cylinder having respective valve inlet and outlet ports; a set of aligned pistons axially slidable in each set of cylinders and comprising a motor reaction piston in' a respective motor cylinder, a pump piston in a respective pump cylinder, spool valve lands in the respective valve cylinders, and respective stems each connecting a respective motor reaction piston to a respective valve land and constituting therewith a respective slide valve spool which is slidable in a respective. valve cylinder to provide a respective control valve; each of said pump and 'motor units having means defining a plurality of transfer ports each connecting a respective reaction cylinder to a respective valve cylinder circu'mferentially displaced therefrom; and a wobble-movement connector linked to said piston sets and constraining them to maintain a timed stroke relationship such that said control valves will operate to connect said transfer passages alternately to the respective inlet and outlet ports so as to switch from intake to return flow precessively in said reaction cylinders. V

3. A hydraulic transformer comprising a motor unit operable by a fluid atone pressure and an axially-opposed pump unit for pumping a fluid at another pressure, said units including means defining respective annular arrays of reaction cylinders of different diameters and valve cylinders aligned with the respective reaction cylinders, the cylinders of one array being aligned with those of the other; and respective piston sets each including pistons slidable in the respective reaction cylinders, spool valve elements slidable in the respective valve cylinders to provide respective flow-control valves, and reduced diameter stems integrally connecting the spool valve elements to the respective pistons in alignment therewith, inlet and outlet ports connected to the respective valve chambers in axially-spaced relation; transfer passages each connecting' a respective valve" cylinder to a respective cir cumferentially-disposed reaction cylinder; and control means comprising a wobble-plate having universallypivotal connections with the inner ends of respective pistons, coupling said piston sets to one another'so as to transmit both pumping strokes and return strokes to the pistons of the pump unit in response to power strokes of the pistons of said motor, and operative to control precessive stroking of said pistons such that said valves will operae to connect said transfer passages alternately to said inlet and outlet ports so as to switch from intake to return flow precessively in said reaction cylinders.

4. A hydraulic transformer comprising axially-opposed motor and pump units including respective housing means having respective annular arrays of motor reaction cylinders, pump reaction cylinders and corresponding valve cylinders, said cylinders being arranged in sets each comprising a motor cylinder, a pump cylinder and a respective valve cylinder aligned on a common axis, each valve cylinder having respective valve inlet and outlet ports; a set of aligned pistons axially slidable in each set of cylinders and comprising a motor reaction piston in a respective motor cylinder, a pump piston in a respective pump cylinder, spool valve lands in the respective valve cylinders, and respective stems each connecting a respective piston to a respective valve land and constituting therewith a respective slide valve spool; each of said pump and motor units having means defining a plurality of transfer ports each connecting a reaction cylinder to a valve cylinder; and a Wobble-movement connector linked to said piston sets and constraining them to maintain a timed stroke relationship such that said valve spools Will operate to connect said transfer passages alternately to the respective inlet and outlet ports so as to direct incoming fluid through the valve of one set to the reaction cylinder of another set of the same circumferential array while directing exhaust flow from the reaction cylinder of one set through the valve of another set and thence to the respective outlet port.

5. A hydraulic transformer as defined in claim 3, wherein the motor unit cylinders and pistons are aligned with respective pump unit cylinders and pistons, wherein aligned valve pistons have opposed ends in direct abutting, pressure transmitting engagement, and wherein said abutting ends are coupled to said connector so as to maintain said abutting engagement at all times, and so that return strokes of the pump pistons will be transmitted to them through said connector.

References Cited by the Examiner UNITED STATES PATENTS 2,293,076 8/1942 Ponting 103-49 2,356,917 8/1944 Chouings 10349 2,592,940 4/1952 Monoyer 103-51 ROBERT M. WALKER, Primary Examiner.

Claims (1)

1. A HYDRAULIC TRANSFORMER COMPRISING A MOTOR UNIT OPERABLE BY ONE FLUID AND AN AXIALLY-OPPOSED PUMP UNIT FOR PUMPING ANOTHER FLUID, SAID UNITS INCLUDING MEANS DEFINING RESPECTIVE ANNULAR ARRAYS OF REACTION CYLINDERS AND VALVE CYLINDERS; AND RESPECTIVE PISTON SETS EACH INCLUDING PISTONS SLIDABLE IN THE RESPECTIVE REACTION CYLINDERS AND SPOOL VALVE ELEMENT SLIDABLE IN THE RESPECTIVE VALVE CYLINDERS TO PROVIDE RESPECTIVE FLOW-CONTROL VALVES; INLET AND OUTLET PORTS CONNECTED TO THE RESPECTIVE VALVE CHAMBERS IN AXIALLY-SPACED RELATION; TRANSFER PASSAGES EACH CONNECTING A RESPECTIVE VALVE CYLINDER TO A RESPECTIVE CIRCUMFERENTIALLY-DISPLACED REACTION CYLINDER; AND CONTROL MEANS COUPLING SAID PISTON SETS FOR PRECESSIVE STROKING OF SAID PISTONS SUCH THAT SAID VALVES WILL OPERATE TO CONNECT SAID TRANSFER PASSAGES ALTERNATELY TO SAID INLET AND OUTLET PORTS SO AS TO SWITCH FROM INTAKE TO RETURN FLOW PRECESSIVELY IN SAID REACTION CYLINDERS; SAID ANNULAR ARRAYS OF CYLINDERS BEING ARRANGED WITH EACH REACTION CYLINDER ALIGNED WITH A RESPECTIVE VALVE CYLINDER AND WITH THE CYLINDERS OF ONE ARRAY ALIGNED WITH THE CYLINDERS OF THE OTHER ARRAY; SAID PISTONS BEING ARRANGED IN OPPOSED, ALIGNED PAIRS, EACH PAIR HAVING ABUTTING ENDS IN THE FORM OF HEADS WITH UNIVERSALLY PIVOTAL BEARING SURFACES, AND HAVING REDUCED NECKS CONNECTING SAID HEADS TO THEIR RESPECTIVE PISTONS; SAID CONTROL MEANS COMPRISING A NUTATING WOBBLE-PLATE HAVING PERIPHERAL SOCKET MEANS, AND BEARING PADS CONFINED IN SAID SOCKET MEANS IN UNIVERSALLYPIVOTAL, EMBRACING BEARING ENGAGEMENT WITH THE ABUTTING HEADS OF RESPECTIVE PISTON PAIRS SO AS TO TIE THE SETS OF PISTONS TOGETHER TO TRANSMIT RETURN STROKES TO THE VALVE PISTONS, WITH THE HEADS OF THE RESPECTIVE PAIRS IN PRESSURE-TRANSMITTING RELATION SO AS TO DIRECTLY TRANSMIT PRESSURE FORM ONE PISTON OF A PAIR TO THE OTHER ALONG THE COMMON LONGITUDINAL AXIS OF THE PAIR OF PISTONS.

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