US2484884A

US2484884A - Hydraulic transformer

Info

Publication number: US2484884A
Application number: US675566A
Authority: US
Inventors: John C Hanna
Original assignee: HANNA ENGINEERING WORKS
Current assignee: HANNA ENGINEERING WORKS
Priority date: 1946-06-10
Filing date: 1946-06-10
Publication date: 1949-10-18
Anticipated expiration: 1966-10-18

Description

0a. is, 1949.

J. c. HANNA HYDRAULIC TRANSFORMER 6 Sheets-Sheet 1 Filed June 10, 1946 I j7ZU67Z/Z 0f JQ/Zm G Haram, wwgme%f Oct. 18, 1949. J, c, HANNA 2,484,884

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Oct. 18, 1949.

Filed-June 10, 1946 J. C. HANNA HYDRAULIC TRANSFORMER 6 Shee ts-Sheej'. 3

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Oct. 18, 1949. J. c. HANNA HYDRAULIC TRANSFORMER 6 Sheets-Sheet 4 I Filed June 10, 1946 Oct Jfc. HANNA 2,484,884

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HYDRAULIC TRANSFURMER Filed; June 10, 1945 6 Sheets-Sheet 6 fmerzz or;

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Patented Oct. 18, 1949 HYDRAULIC TRANSFORMER John 0. Hanna, Chicago, 111., assignor to Hanna Engineering Works, Chicago, 111., a corporation of Illinois Application June 10, 1946, Serial N0. 675,566

12 Claims.

The invention relates to hydraulic pressure boosters and has reference in particular to an improved device of this character which will transform a low pressure liquid into a high pressure liquid and wherein the reduction, in volume of the high pressure liquid will be inversely proportional to the increase in pressure.

An object of the invention is to provide a combination pump and motor device of the difierential piston type which will operate on a liquid of a low pressure to raise a predetermined portion of said low pressure liquid to a higher pressure, which will be compact, embodying a minimum of operating parts, and wherein said parts will be contained in a single unit of leakproof construction.

Another object of the invention is to provide a hydraulic transformer of the character described which will incorporate a novel distributor valve for controlling the flow of low pressure liquid to the differential piston which operates as a pump of constant displacement.

A more specific object resides in the provision of a hydraulic transformer incorporating a distributor valve of the rotating type and which valve is hydraulically balanced by the balanced oil pressure acting upon it.

Another object of the invention is to provide a hydraulic transformer wherein the selector or rotating distributor valve in controlling the flow of the low pressure liquid to the differential piston will produce four pumping strokes of said piston per revolution.

Another object is to provide an improved hydraulic transformer incorporating a rotating distributor valve which will require the minimum in power to rotate it since the same is hydraulically balanced and which transformer will deliver a constant flow of high pressure liquid, the volume of which compared to the volume of low pressure liquid entering the device will be inversely proportional to the boost in pressure.

With these and various other objects in view, the invention may consist .of certain novel features of construction and operation as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the invention, and wherein like reference characters are used to designate like parts- Figure 1 is a longitudinal sectional view taken substantially centrally of the hydraulic transformer of the invention showing the rotary distributor valve and the differential piston;

Figure 2 is a transverse sectional view taken substantially along line 22 of Figure 1;

Figure 3 is a transverse sectional view taken substantially along line 33 of Figure 1;

Figure 4 is an end view of the hydraulic transformer looking in the direction of the arrows on line v l l of Figure 1;

Figure 5 is an end view of the auxiliary piston assembly;

Figure 6 is a longitudinal sectional view of the auxiliary piston assembly;

Figure 7 is a schematic arrangement illustrating the operating parts of the present hydraulic transformer, their relation with each other, and the complete hydraulic circuit for their operation;

Figure 8 is another view illustrating the arrangement of the various devices and their connection as may be required for a complete hydraulic circuit for :the transformer; and

Figure '9 is a transverse sectional View taken substantially along line :B-9 of Figure 1.

Referring to the drawings, and in particular to Figures 1 and 8, the hydraulic transformer of the invention is shown as including a unitary housing Ill which contains all the operating parts of the device and which is composed of several units including a central unit ll, an inlet unit l2, an outlet unit l3 and a bearing unit 14. The inlet and outlet unit are bolted .to opposite sides of the central unit by the securing screws 15 shown in Figures 2 and .3 and the bearing unit is secured to I2 by the screws "5, as shown in Figures 1 and 4.

The housing H) which operates as a pressure booster is connected in the hydraulic circuit as disclosed in Figure 8, wherein the reservoir is indicated by numeral l1 and the low pressure oil pump IB is suitably associated therewith as by being supported on top of the reservoir. An oil inlet line 20 extends from within the reservoir H to the inlet side of the pump l'8 which is driven by motor 2 I, the shaft 22 of the motor providing a sprocket '23 and connecting with the shaft 24 back to the reservoir.

of the pump by means of the coupling unit 25. A relief valve 26 is connected. in line 2'! from the pump and which supplies low pressure oil to the auxiliary piston assembly 25 to be described in detail as the description proceeds. The low pressure oil leaves the assembly 28 by line 31'] which comprises the inlet for the hydraulic transformer ii], the inlet line 3" connecting with Ill, as best shown in Figure l. The hydraulic transformer is provided with two outlets, one a low pressure outlet and the other a high pressure outlet. The former is indicated by the line 31 and which returns the low pressure oil from the transformer The high pressure line 32 leads from the outlet unit l3 of the hydraulic transformer, as clearly evident from Figure 1, and is provided with the T connection 33, one end of which is associated with the auxiliary piston assembly 28.

The operating shaft 3 1- of the hydraulic transformer is provided with sprocket 35, Figure 8, and this sprocket is driven by sprocket "23 by means of an endless chain operatively connecting the said sprockets so that the motor 2i com-- prises the source of power for the low pressure pump and the transformer and which two devices are driven in unison.

Shaft 35- is journalled by the bearing member 85 of the transformer, the ball bearing assembly 35 being provided for substantially frictionless rotation and the inner end of said shaft being reduced to form the key 37 which interlocks with the adjacent end of the rotating distributor valve 38. Said valve is cylindrical in general form and is suitably journalled for rotation by the housing it. At the inlet end of the distributor valve an internal passage 45 is formed having openings 4| which communicate with the chamber 42 connecting with the inlet conduit 3|] so that low pressure oil is supplied to passage 50, the same entering through the openings ll as the valve rotates. At the opposite end of passage 45 a pair of outlet ports &3 are located, the same being positioned diametrically of the distributor valve 33. In accordance with the invention the diametrical outlet ports are adapted to align with certain conduits or passages formed in the housing and which conduct the low pressure oil to the differential piston, which structure will be presently described in detail.

Referring again to the distributor valve, the outlet end-of the same is also provided with an internal passage 44 having openings 45 which communicate with the chamber 45 connecting with the outlet 3d. The low pressure oil from said passage 35 is accordingly discharged through openings 45 and the same leaves the housing In by the outlet line 3i. The passage Mi also has a pair of ports 47 which, as regards this end of the valve, function as inlet ports, the same being positioned diametrically and aligning with certain conduits or passages in the housing, which conduct the low pressure oil from the diiferential piston. The diametrical position of the outlet ports 47 transversely of the valve 38 is at right angles to the inlet ports 43, Figure 7.

The diiferential piston is located within the housing below the valve 38 and includes a center piston 58 of large diameter positioned within the chamber '55 and having reciprocating movement in said chamber from end to end since the chamber has a length somewhat greater than that of the piston 48. An extension is provided on each end of piston 48 and these form the high pressure pistons, the one on the right hand end, Figure 1, being indicated 5!, and the piston 0n the left hand end being indicated 52. It will be seen that the high pressure pistons are much smaller in diameter than the center or low pressure piston, the ratio of their diameters determining the pressure ratio between the low and high pressure oil. For example, if the high pressure pistons have a diameter and thus an area which is onefifth that of the large piston, then the high pressure oil will have a pressure which is approximately five times that of the low pressure oil. However, the volume of the high pressure oil will be one-fifth of that of the low pressure oil delivered to, the transformer. It will be seen that the chamber for piston 48 is provided by the central unit II. The inlet unit 12 provides a chamber 53 for the high pressure piston 52, whereas, the outlet unit I3 in a similar manner provides chamber 54 for the high pressure piston 52, Figure '7. Cushioning or shock absorbing members 55 are located at the respective ends of the chamber 50 to cushion the movement of the piston 48 at each end of its stroke, the members being backed by the coil springs 55.

Chamber 53, accommodating the high pressure piston 5 I, has communication with a vertical bore 51, Figure 1, formed in the inlet unit 12 0f the device. This bore has connection with a duct which will be presently described by which it is supplied with low pressure oil and for controlling the inlet of this low pressure oil to chamber 53 the vertical bore is equipped with an insert 58 containing a ball check valve 65 which opens to admit the low pressure oil and closes to prevent its flow except through openings 6! which deliver into chamber 53 where the low pressure oil acts against piston 5i and is in turn acted on by said piston.

The base of vertical bore 51 is somewhat enlarged to receive another insert 62 providing the ball check valve 63, which, however, opens downwardly to admit high pressure oil from above and closes to prevent its flow except through openings 64 in the said insert and which thus delivers the high pressure oil to a longitudinal passage or duct 65 having communication with the ball valve 63 through said openings. The ball check valves and 63 are so constructed and tensioned by their associated coil springs that valve 59 will open when subjected to low pressure oil and valve 631 will open only when subjected to high pressure 01.

The outlet unit I3 is likewise provided with a vertical bore 66, similar to 51, and which has connection with a duct to be described, by which the bore is supplied with low pressure oil at definite times in the rotary movement of the distributor valve 38. For controlling the inlet of this low pressure oil to chamber 54 the vertical bore is equipped with an insert 61 providing the ball check valve 68 which opens to admit said oil and closes to prevent its back flow so that the oil flows out through openings 69 into chamber 54 where it acts on piston 52 and is in turn acted on by said. piston. The base of vertical bore 66 is enlarged to receive another insert 15 providing ball check valve H. The valve H, however, opens downwardly to admit high pressure oil from above and closes to prevent flow except through openings 12 in the insert. The oil flowing through openings 12 is admitted to the duct communicating therewith and the said duct 65 extends through and beyond the vertical bore 66 to connect with the vertical passage 13 comprising the high pressure oil outlet of the hydraulic transformer. This outlet connects with the high pressure oil line 32, as shown in Figure 1. As regards the ball check valves 68 and II, it is also understood that they are constructed and tensioned by their coil springs to open when subjected to low pressure oil and high pressure oil, respectively,

The various ducts or passages provided by the hydraulic transformer and which conduct low pressure oil from the distributor valve 38 to the respective ends of the differential piston will now be described. These ducts are best shown in the schematic arrangement of Figure 7. The central unit l I of the device adjacent the end toward the inlet unit I2 is formed with a long vertical duct Hi and a short vertical duct 15, the same being positioned on opposite sides of the longitudinal center of the device. Both ducts 14 and 15 have

openings

16 and 11, respectively, communicating with the right hand end of chamber 50, Figures 1, 2 and 7. The vertical duct 14, which extends above the distributor valve on the right hand side of the same, Figure 2, connects at its upper end with a horizontal duct 18, and said duct in turn connects with an inlet passage 80 and an outlet passage 8i, the same having an inclination of about forty-five degrees and extending to the distributor valve 38. It will be understood that the passages 88 and 8| are positioned so as to align with the

ports

43 and 41 spaced lengthwise of the distributor valve. The vertical duct 15 connects at its upper end with a horizontal duct 82 which at one end connects with an inlet passage 83 and an outlet passage 84. The passages 83 and 84 extend to the distributor valve and the same are positioned to align with

ports

43 and 41, respectively. 'Also said passages have a forty-five degree inclination and are substantially in opposed relation to passages 80 and 8! previously mentioned. The opposite end of horizontal duct 82 has connection with a vertical duct 85 forming an extension of the same and which duct communicates with the vertical bore 51, Figures 1 and 4.

A similar arrangement of ducts and passages are provided for the left hand end of chamber 58, as will be clear from Figures 3 and 7. The long vertical duct 86 and the short vertical duct 8'?! are reversed with respect to the ducts '14 and 75. However, openings are formed at their lower ends, indicated by numerals 88 and '89, respectively, and which communicate with the left hand end of chamber 50. The long vertical duct 86 connects at its upper end with a horizontal duct M, which in turn connects with an inlet passage 9i and an outlet passage 92, the passages aligning with the

ports

43 and 41 and extending to the distributor valve. The short vertical passage 81 on the opposite side of the distributor valve 38 has connection at its upper end with a horizontal duct 83 which at one end connects with an inlet passage 94 and an outlet passage 95. These passages are inclined forty-five degrees and extend to the distributor valve, being aligned with ports 43 and ll and in substantial opposed relation with 9! and 92. It will also be observed that each set of inlet and outlet passages are disposed around the distributor valve in spaced relation of approximately ninety degrees So that with each quarter turn of the valve a difierent set of passages are aligned with the inlet and outlet ports t3 and 41. The end of the horizontal duct '93 has connection with a duct 96 which leads in 6 a downward direction similar to 8 5 and communicates with the vertical bore 66.

This completes the arrangement of ducts and passages connecting the distributor valve with the differential piston in accordance with the invention and the operation of the parts for each half revolution of the valve will be explained.

Referring to Figure '7, it will be understood that low pressure oil from line 30 will have entered the distributor valve 38, that is, the inlet passage Lid of the valve through openings 41, and assuming the valve to be positioned, as shown in Figure 7, the low pressure oil Will be delivered by ports it to the inlet passages and 83 which are aligned with the ports. This flow of oil is conducted by the ducts M and 15 to the right hand end of chamber 58, the same entering this end of the chamber through the openings 16 and ll, respectively. The piston 48 is located at the right hand end of chamber 58 and thus the low pressure oil acts on the piston to cause it to move in a direction toward the left. The oil is also conducted by

ducts

82 and 85 to the vertical bore 5'1, the oil entering the insert 58 through the check valve til which opens to admit flow of the oil in this direction. As previously explained, this low pressure oil will enter chamber 53 and act on piston 55 so that the full area of the differential piston is subjected to pressure exerted by the low pressure oil and it accordingly moves to the left end of chamber 58.

As piston moves to the left the oil in chamher 5% in front of piston 48 is caused to flow out through the openings 88 and 89 into ducts 86 and 8'? which deliver the oil to the outlet passages 92 and 95. These passages, at this instance in the rotary movement of the valve 38, .are in alignment with the ports 4! so that the oil enters the valve 38 and subsequently is delivered to the outlet 39 which returns this low pressure oil to the reservoir, Figures 7 and 8.

The oil in front of the high pressure piston 52 is acted on by said piston as the same moves toward its extreme left hand position and this oil is compressed to a high pressure. Assuming the area of piston 52 to be one-fifth of the crosssectional area of piston 58, then the oil will be increased in pressure five times that of the low pressure oil but its volume will be only one-fifth of the volume of oil acting on the differential piston and causing it to move to the left and compress the oil to its high pressure. This high pressure oil from chamber 54 is caused to ilow into insert 'lll through the ball check valve 'H which opens to admit said oil flow and which is delivered to the outlet 73 and thus to the high pressure line 32.

The differential piston remains in position at the left end of

chambers

58 and 54 as the rotary valve 38 continues to rotate and upon rotation of approximately ninety degrees the ports 43 align with the

inlet passages

93 and 94 so that low pressure oil is delivered to these passages. Since said passages connect with the

ducts

86 and 87 the low pressure oil is admitted by openings 88 and 89 to the left end of chamber 58 Where it acts on piston 48 to cause the piston to move to the right. The oil is also conducted by ducts '93 and it to vertical bore 68 and it enters insert El through the ball check valve 88 which opens to admit flow in this direction. From the insert the oil enters the chamber 54 to act on piston 52 to augment the action of the oil on piston 38.

As the differential piston moves to the right the oil in front of piston 48 is returned to ducts and T5 and delivered to outlet passages 8i and 84 which at this instance are inalignment with the ports 41. This low pressure oil enters the passage 44 in the valve '38 and is eventually delivered to line 3! and returned to the oil reservoir. The oil in front of piston 5| is compressed to the high pressure, as previously explained, and is forced to enter insert 62, the ball check valve 63 opening to admit this flow of high pressure oil. From the insert 62 the oil is delivered to duct 65 and then to outlet 13 and to the high pressure line 32.

The differential piston remains in position in the right hand end of chambers 50 and 53 as the rotary valve 38 continues its rotation. Upon another ninety degree turn of the valve the ports 43 will be caused to again align with inlet passages 8B and S3 and the ports 47 with outlet passages 92 and 95. The operation first described is thus repeated and the differential piston will be moved to the left as has been described to compress the oil in front of piston 52. Thus the valve 38 in rotating one hundred and eighty degrees has produced two strokes of the differential piston, or, in other words, two pumping strokes for high pressure oil. For a full revolution of the valve it follows that four pumping strokes of the differential piston result.

From the foregoing it will be understood that the distributor valve 38 functions as a control member for directing the flow of low pressure oil to the differential piston. For each ninety degree rotative position of the valve certain inlet passages are supplied with low pressure oil from line 30 and certain. outlet passages are connected to the outlet line 3| for discharge of low pressure oil. The fluid medium which is elevated to the high pressure for which the device is designed is acted on by the small diameter pistons 5i and 52. In the first instance this medium at low pressure does its share of work in reciprocating the differential piston and then the same fluid medium is acted on by the piston being compressed to the high pressure and eventually discharged through the outlet line 32.

The rotary distributor valve 38 requires very little power since the valve is hydraulically balanced by the balanced oil pressure acting on it. Flow into the valve takes place symmetrically through the openings Q! and is discharged in a similar manner through openings 45. Also the arrangement of the

ports

43 and 47 is symmetrical so that the outflow and inflow of the low pressure medium is balanced and the load on the valve is a minimum.

The hydraulic transformer delivers the high pressure 011 by the to and fro strokes or reciprocations of the double ended differential piston. As the said piston moves in one direction, due to low pressure oil behind it, the high pressure piston on the forward end is compressing oil to a high pressure. It follows that when the differential piston reaches the end of its stroke in one direction, the flow of both high and low pressure oil will momentarily cease. If it were not for the auxiliary piston assembly 28, Figures 5, 6, 7 and 8, the low pressure oil would rise in pressure if the latter exceeds the pressure resistance opposed against this fiow and the high pressure oil would drop in pressure. As the low pressure oil tends to rise in pressure between strokes of the differential piston, the large end 98 of the auxiliary piston is acted on by this now slightly higher low pressure oil. Said low pressure oil, due to its somewhat higher pressure, acts on the large end 98 of the auxiliary piston to move the piston in a direction toward the right, Figur 6, causing the coil spring I00 to be compressed and the small piston end llll to displace an amount of oil sufiicient to augment the high pressure oil in

lines

32 and 33, which has ceased to flow from the transformer.

The auxiliary piston will function at each reversal in the movement of the differential piston. The area ratio of the large piston end 98 and the small piston end [0! is actually the same as the area ratio of the differential piston. The function of the coil spring 500 is to return the piston 98 to its normal position, as shown in Figure 6, after it has made the movement as described, which is necessary to assure even flow of high pressure oil during reversals in the strokes of the differential piston.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawing as various other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

What is claimed is:

1. In a hydraulic booster, a housing member having an inlet passage connectin with a source of fluid pressure, an exhaust passage connecting with an exhaust line, and a high pressure delivery line connecting with an outlet passage for a high pressure fluid, a differential piston within the member mounted thereby for reciprocating movement, said differential piston including a main operating piston having reciprocating movement within a chamber provided therefor by said member and ram pistons extending from each end of the main piston and which move in chambers respectively also provided by said member, a passage in the member associated with each ram piston chamber at the end thereof and connecting with said outlet passage, a distributor valve journalled by said member for rotation and extending in an axial direction from the inlet passage to said exhaust passage, control ports provided by the valv and connecting with the inlet passage, other control ports provided by the valve and connecting with the exhaust passage, a plurality of ducts formed in the member and having associated relation at one end with the said control ports respectively, and at their other ends having connection with certain ends of the operating piston chamber, and certain of said ducts having connection with the end of the ram piston chambers respectively.

2. In a hydraulic booster, a housing member having an inlet passage connecting with a source of fluid pressure, an exhaust passage connecting with an exhaust line, and a high pressure delivery line connecting with an outlet passage for high pressure fluid, a differential piston with the member mounted thereby for reciprocatin movement, said diiferential piston including a main operating piston having reciprocating movement within a chamber provided therefor by saidports-provided by the valve, being located diametrically of the same and connecting with the inlet passage, other control ports provided by the valve, being located diametrically of the same but displaced ninety degrees with respect to the first mentioned control ports and connectin with the exhaust passage, a plurality of ducts formed in the member and having associated relation at one end with the said control ports respectively, and at their other ends connecting with certain ends of the operating piston chamber, and certain of said ducts having connection with the end of the ram piston chambers respectively.

3. A hydraulic booster as defined by claim 1 additionally including a check valve adjacent and in communicating relation with the end of each ram piston chamber between the same and the passage associated therewith.

4. An hydraulic booster as defined by claim 1 additionally including a pair of check valves in spaced relation adjacent each ram piston chamber and in communicating relation therewith, one check valve in each pair being located between its respective chamber and the duct connecting therewith, and the other check valve of each pair being located between its respectiv chamber and the passage associated therewith.

5. In a hydraulic booster, a housing member having an inlet passage connecting with a source of fluid under pressure, an exhaust passage connecting with an exhaust line, and an outlet passage connecting with a high pressure delivery line, a diiferential piston within the member mounted thereby for reciprocating movement, said differential piston including a main operating piston having reciprocating movement within a chamber of greater length than the same and provided therefor by said member, and including ram pistons extending from each end of the main piston and which move in chambers respectively also of greater length than the respective ram piston and provided therefor by said member, a passage formed in the member for each ram piston chamber having connection with the end of its ram piston chamber and connecting with the outlet passage, each said passage delivering fluid to the outlet passage after compression of the same to a high pressure by its ram piston, at least one duct formed in the member for each ram piston chamber and connecting with the end of the same for admitting the fluid under pressure to the chamber, other ducts in the member having connecting relation respectively with the ends of the main piston chamber for alternately admitting and exhausting said pressure fluid whereby to produce reciprocating movement of the main operating piston and said ram pistons, and means controlling the admission of the pressure fluid to said ducts for delivery to the ram piston chambers and main operating piston chamber and exhausting of the pressure fluid from the latter chamber, said means including a distributor valve journalled by the member and having control ports connecting with the inlet passage and other control ports connecting with the exhaust passage.

6. An hydraulic booster as defined by claim 5 additionally including a check valve adjacent and in communicating relation with the end of each ram piston chamber between the same and the passage for said chamber.

7. A hydraulic booster as defined by claim 5 additionally including a pair of check valves in spaced relation adjacent each ram piston chamber and in communicating relation therewith, one check valve in each pair being located be- 10 tween its respective chamber and the duct connecting therewith, and the other check valve of each pair being located between its respective chamber and the passage for said chamber.

8. In a hydraulic booster, in combination, a differential piston mounted for reciprocating movement, said piston including a main operating piston and a ram piston extending from each end of the said main piston and of less diameter than the main piston, a main piston chamber and ram piston chambers associated therewith, said main and ram pistons having location within said chambers respectively, each ram piston chamber extending from its end of the main piston chamber, mechanism for effecting reciprocating strokes of the diiferential piston including means for delivering a fluid under pressure to either end of the main piston chamber, means for simultaneously discharging the fluid from the opposite end of the chamber, and means for also delivering a fluid under pressure to the respective rear ram piston chamber behind the ram piston thereof, whereby the forward ram piston is caused to compress the fluid within its chamber to a pressure higher than the initial pressure of the fluid, said mechanism including a rotary distributor valve having a controlling operation by reason of its rotation for controlling the delivery to and discharge from the various chambers of said fluid under pressure.

9. In a hydraulic booster, in combination, a differential piston mounted for reciprocating movement, said piston including a main operating piston and a ram piston extending from each end of the said main piston and of less diameter than the main piston, a main piston chamber and ram piston chambers associated therewith, said main and ram pistons having location within said chambers respectively, each ram piston chamber extending from its end of the main piston chamber, a pair of check valves at the outer end of each ram piston chamber for controlling the delivery to and exit from said chamber of a fluid, mechanism for effecting reciprocating strokes of the differential piston including means for delivering a fluid under pressure to either end of the main piston chamber, means for simultaneously discharging the fluid from the opposite end of the chamber, and means for also delivering a fluid under pressure to the respective rear ram piston chamber behind the ram piston thereof, whereby the forward ram piston is caused to compress the fluid within its chamber to a pressure depending on the setting of the check value controlling the exit of the fluid from the chamber, said mechanism including a rotary distributor valve having a controlling operation by reason of its rotation for controlling the delivery to and discharge from the various chambers of said fluid under pressure.

10. In an hydraulic transformer having an inlet for supplying a low pressure oil thereto, a low pressure oil outlet, and a high pressure oil outlet for delivering oil at a higher pressure, a double ended reciprocating piston provided by said transformer for pumping said high pressure oil by the to and fro strokes of said piston, whereby the flow of both high and low pressure oil momentarily ceases when the reciprocating piston reaches the end of its stroke in either direction, and an auxiliary piston assembly for counteracting any rise in pressure of the oil in the low pressure oil inlet and any drop in pressure of the oil in the high pressure oil outlet caused by said stoppage in the flow of 011, said auxiliary piston assembly having 11 connected relation with both the low pressure oil inlet and the high pressure oil outlet and including a double-ended piston having a large diameter end and a small diameter end and subjected to the low and high pressure oil at the ends respectively.

11. In an hydraulic transformer having an inlet for supplying a low pressure oil thereto, a low pressure oil outlet, and a high pressure oil outlet for delivering oil at a higher pressure, a double ended, differential piston mounted for reciprocation by said transformer for pumping said high pressure oil by the to and fro strokes of said piston, whereby the flow of both high and low pressure oil momentarily ceases when the reciprocating piston reaches the end of its stroke in either direction, and an auxiliary piston assembly for counteracting any rise in pressure of the oil in the low pressure oil inlet and any drop in pressure of the oil in the high pressure oil outlet caused by said stoppage in the flow of oil, said auxiliary piston assembly having connected relation with both the low pressure oil inlet and the high pressure oil outlet and including an auxiliary piston having a large diameter end subjected to the low pressure oil and a small diameter end subjected to the high pressure oil, and said auxiliary piston having a non-pumping action.

12. In an hydraulic transformer for increasing the pressure of a fluid medium delivered thereto and wherein the volume of the high pressure medium compared to the volume of the low pressure medium entering the device is inverselyproportional to the boost in pressure, the combination with an inlet and an outlet for the low pressure medium, an outlet for said high pressure medium,

a reciprocating double ended piston for pumping said high pressure medium by the to and fro strokes of the same, an auxiliary piston assembly having connected and operative relation with both the low pressure inlet and the high pressure outlet, said auxiliary piston assembly having operation at each reversal in the movement of the double ended pumping piston to maintain an even flow of the high pressure medium from said high pressure outlet said auxiliary piston assembly including an auxiliary piston having a large diameter end and a small diameter end, the large diameter end of said piston having associated relation with the inlet and being subjected to the low pressure medium, the small diameter end having associated relation with the outlet and being subjected to the high pressure medium, and said auxiliary piston having a non-pumping action.

JOHN C. HANNA.

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

UNITED STATES PATENTS Number Name Date 38,531 Coates et a1 May 12, 1863 617,934 Mason Jan.'17, 1899 1,377,585 Johanson May 10, 1921 2,053,543 Vincent Sept. 8, 1936 2,239,727 Mayer Apr. 29, 1941 FOREIGN PATENTS Number Country Date 285,985 Italy May 28, 1931