US3014464A - Fluid converters - Google Patents

Description

1 A. B. BARNES ETAL 3,014, 64

FLUID CONVERTERS Filed March 28, 1960 5 Sheets-Sheet 2- IO I J ,7, J8

FIG. 4.

//YAV x G Inventors:

AUSTEN B. BARNES b FRANCIS H.A.MEE

Dec. 26, 1961 A. B. BARNES ETAL 3,014,

FLUID CONVERTERS 5 Sheets-Sheet 3 Filed March 28, 1960 Inventors AUS'TEN B. BARNES FRANCIS H.A.MEE

Dec. 26, 1961 Filed March 28, 1960 A. B. BARNES EI'AL FLUID CONVERTERS 5 Sheets-Sheet 4 FIG- 8 Inventors AUSTEN B. BARNES FRANCIS H.A. ME'E WUMM 1961 A. B. BARNES ET AL 3,014,464

FLUID CONVERTERS Filed March 28, 1960 5 sheets-sheet 5 85 a4 73 as a? 8 a9 92 a3 78 Inventcrs AUSTEN B. BARNES FRANCIS H.A.MEE

United States Patent Ofliice 3,014,464 FLUID CGNVERTERS Austen Bernard Barnes, Willowdale, Ontario, and Francis Herbert Arthur Mee, Aurora, ()ntario, Canada, assignors to De Havilland Aircraft of Canada, Limited Filed Mar. 28, 196i), Ser. No. 18,011

13 Claims. (Cl. 121-123) This invention relates to a fluid converter and more particularly to means for converting energy from fluid under pressure into mechanical motion and further to means for pumping fluids.

It is amongst the objects of this invention to provide a converter of simple construction employing only two basic moving assemblies.

It is also amongst the objects of the invention to provide a double acting converter.

It is further amongst the objects to provide a converter in the form of a motor capable of converting energy from fluid under pressure to mechanical motion.

It is still further amongst the objects of the invention to provide a converter in the form of a double acting pump for fluids.

Further objects and advantages of the invention will become apparent from a consideration of the following description and the drawings, in which:

FIGURE 1 shows a cross-sectional view of a converter in the form of a basic embodiment of a motor in accordance with the invention;

FIGURE 2 shows a similar cross-section but with the valve and piston in a diiierent position;

FIGURE 3 shows a fractional cross-section of a modification to the forms of FIGURES 1 and 2;

FIGURE 4 shows a cross-sectional view of a motor incorporating various self starting features;

FIGURE 5 shows a cross-sectional view illustrating a form of gas cushioning employable with the invention;

FIGURE 6 shows a cross-section of a further embodiment of a converter in the form of a motor in accordance with the invention;

FIGURE 7 showsa cross-sectional view along the lines 7-7 of FIGURE 6;

FIGURE 8 shows a cross-sectional view of a further embodiment of a converter in the form of a motor in accordance with the invention; and

FIGURE 9 shows a crosssectional View of a converter in the form of a pump in accordance with the invention.

Referring now to the drawings in which similar parts are given the same numerical designation throughout and referring more particularly to FIGURE 1, there is shown a motor having an outer casing or cylinder 1%, piston 11, piston rod 12 and valve 13. Gas under pressure is introduced into inlet port 14 and flows around the annular groove 15 in valve 13 and thence into labyrinth passage 16, annular chamber 17, piston port 13 and reaches the right hand end-200i cylinder 1i through passage 19, thereby forcing the piston 11 to the left. At the same time, gas entering inlet 14 and annular groove 15 passes through labyrinth passage 21 to space 22 where it holds thevalve 13 hard against the piston 11, thereby keeping the port open as long as possible with the volume at 23 being zero.

The piston moves toth'e left and as it does so the annular groove 15 moves out of alignment with inlet port 14, and valve land 24 begins to block inlet port 14. Gas or fluid is still capable of entering inlet port 14 until valve land 24 completely closes the port. (See FIGURE 2.) At this stage the inertia of the piston 11 and the-continued expansion of the gas or fluid will cause the closing lip of land 24 to actually pass the edge oi inlet port 14. In the case where a liquid is used, the inertia alone would be relied upon to eifect this part of the movement. This 3,014,464 Patented Dec. 26, 1961 can be accomplished by the Weight of the parts involved. As soon as this occurs, a small area of the annular groove 25 is momentarily exposed to the inlet pressure, and the gas or fluid will pass through annular groove 25 along labyrinth passage 26 and begin to move the valve 13 to the left relative to the piston 11 by introducing gas or fluid to 23. The piston 11 will at this time be almost hard over to the left end of cylinder 10, and thus the valve 13 is free to move under the influence "of gas or fluid proceeding through labyrinth passage 26 until the annular groove 25 is almost fully aligned with the inlet port 14. Meanwhile the gas trapped in space 22 is free to escape via passage 21, annular groove 15 and outlet port 27, which is positioned so that the annular groove 15 aligns with it as annular groove 25 aligns with inlet port 14. Gas from annular groove 25 also enters labyrinth passage 28, and passes therefrom through annular chamber 29, port 30', and passages 31 and 32 into the left hand end 33 of cylinder 10. This occurrence tends to move the piston 11 to the right and the procedure described above for right-to-left movement is reversed. Upon the reverse operation, the gases which at this time would be trapped in space 23 are exhausted through labyrinth passage 26, annular groove 25 and outlet port 34, which is positioned so as to be aligned with annular groove 25 when annular groove 15 is aligned with inlet port 14.

As the spaces at 22 and 23 are uncoupled from the spaces at 26 and 33, lower operating pressures may be employed inasmuch as the only load to be overcome is that of the inertia and friction created by valve 13, plus a small reaction from the gas flow in the labyrinth passages and across the lips of the ports. The gas flow in the valve may therefore be restricted by providing relatively narrow labyrinth passages at 21 and 26. This provides a gain in operating economy. In order to provide quieter operation and prevent metal to metal contacts, it is possible to provide gas cushioning within the motor, as illustrated in FIGURE 5. The basic operation of the motor remains substantially as described with respect to FIG- URE 1. Mechanical means such as springs-or resilient buffer pads may of course be used as an alternative to the gas cushioning cutaway portions shown in FIGURE 5, without departing from the scope of the invention.

By increasing the physical size of the motor while admitting the same quantity of gas or fluid, the gas or fluid may be expanded into a greater volume during the stroke than otherwise. Thus a more eflicient thermodynamic operating cycle can be obtained. A convenient manner of limiting the gas charge is by restricting the size of the main inlet port 14 with respect to the size of annular grooves 15 and 25. Such an arrangement is shown in the partial cutaway of FIGURE 3. This arrangement in eiiect provides an early cutoff for the inlet gases and allows them to expand subsequently.

Where the fluid to be used is liquid and where, therefore, there is no expansion, all the inlet and valve passages would have to be opened fully to permit maximum flow. Apart from this, however, the motor would be of the same form as shown in FIGURES l and2.

Referring now .to FIGURE 4, there are shown various ways of providing self-starting features for the motor. All that is required to ensure self-starting is to provide an unstabilizing force so that the solid shoulder or valve land 24 between grooves 15 and 25 can not remain perfectly aligned with the inlet port 14 during starting. One means of providing such an unbalanced force is by providing a spring 35 which exerts an end thrust on valve 13 with respect to piston 11. As only a very weak spring is necessary, the operation of the valve 13 is not seriously affected. Another method is to provide gas bleedholes 36 in. annular shoulder or valve land 24. The holes 36 would have to be small enough to give the elfect of a long time constant compared with the normal valve operation, but their bleeding effect would be suflicient to cause the valve 13 to be moved slowly off centre if the high pressure gas was connected whilst land 24 was aligned with inlet port 14. A further alternative would be to provide a slight bevel or chamfer 37 to the face 38 of valve land 24. It will be appreciated that whilst three methods have been illustrated as examples in FIGURE 4, it is normally only necessary to incorporate on of these methods to provide a self-starting feature. Whilst the basic form and principles of the motor have been described above, it will be appreciated that various embodiments may be desirable for different purposes.

Referring now to FIGURE there is shown an example of a fully gas cushioned embodiment of the motor referred to previously. Gas cushioning is obtained by the provision of shoulders 39 and 40 on the piston ends and corresponding cut-out portions 41 and 42 in the cylinder 10. Similarly, shoulders 43 and 44 may be provided on the valve 13 with corresponding cut-out portions in the piston 11 so as to gas cushion the valve 13 with respect to the piston 11.

Instead of routing the valving gas through ports cut in the valve, it is possible to duct it through the motor case as shown in FIGURES 6 and 7. In this case, external passage 47 replaces labyrinth passage 21 of FIG- URE 1 and passage 48 replaces labyrinth passage 26 of FIGURE 1. Also, it is possible in using this embodiment of the invention to insert variable restrictions 4-9 and 50 in the passages 47 and 48, thus facilitating the control of the motors operating characteristics. In fact, an unbalanced operation could be attained, if desired, by arranging a greater restriction in one passage than in the other.

It will be noted that inlet 14 and outlets 27 and 34 are positioned so as not to coincide with passages 47 and 48, and that they may conveniently be disposed as shown in FIGURE 7, i.e. in a difierent portion of the cylinder casing 10. Apart from the positioning of passages 47 and 48 in this manner the operation of the motor remains substantially described with respect to FIGURE 1.

FIGURE 8 shows another embodiment of a motor of the invention. The operation is as follows:

Fluid under pressure is admitted through inlet port 51 to annular groove 52, passes therefrom via labyrinth passage 53 into annular chamber 54. At the same time, fluid under pressure is communicated via annular groove 52 and labyrinth passage 55 to the space (initially zero) 59 at the left hand end of the valve 13, thereby forcing the valve 13 to the right relative to piston 11 until annular groove 52 is fully aligned with inlet port 51. At this point, annular passage 54 and piston port 55a are in full communication, allowing fluid to pass through passage 56 to end chamber 57 where it exerts pressure on the end wall of cylinder and thereby moves the piston 11 to the left. Fluid within space 60 will at first escape via outlet 61 until the end piece 62 of piston 11 effects closure thereof. Similarly end piece 63 of piston 11 will at first expel fluid from space 64 via outlet 65. As outlets 61 and 65 are closed, the fluid trapped in space 64 provides automatic cushioning.

Eventually the piston 11 is pushed to the left until the annular groove 52 has passed inlet port 51, and the expanding gas or fluid continues to move the piston 11 such that a small area of the annular groove 66 is momentarily exposed to the inlet pressure, and the gas or fluid passes along labyrinth 67 and begins to move the valve 13 to the left (within the confines of the piston end pieces 62 and 63), byv filling volume 60. As the piston 11 is at this time almost hard over at the left hand end of the cylinder, the valve 13 moves over until annulus 66 is almost fully aligned with inlet port 51. The gas trapped at 59 escapes via exit port 65.

Gas from 66 also enters labyrinth 68 and annular chamber 69, and then flows through the piston port 70 and along passage 71, entering space 64 and pushing the piston 11 to the right. The piston 11 carries the valve along with itself as in the right-to-left movement.

At the end of the stroke, the gas at 64 finally exhausts via 65 as the latter becomes uncovered by the receding piston.

It will be noted that in FIGURE 8 the annular chambers 54 and 69 are of reduced length and are arranged so that annular chambers 54 and 69 and piston ports 55a and 70, respectively, are only communicative when the valve 13 is sufficiently offset relative to the piston 11 as to ensure positive valve operation, with little or no bounce or flutter. It is, of course, possible, by increasing the length of annular chambers 54 and 69, to make them permanently communicate'with piston ports 55a and 70 in a manner similar to the porting arrange ment shown in the other figures.

FIGURE 9 shows a pump for pumping liquids which is generally similar to the motors previously described, but operates from a source of reciprocating mechanical motion. If the piston 11 is moved to the left from the position shown, it slides through the valve 13 until pisfton port 72 is aligned with annular valve chamber 73. When the piston port 74 is in alignment with annular valve chamber 75, the piston 11 begins to drag the valve 13 to the left, the right hand shoulder 76 of the piston 11 being in contact with the right hand end 77 of valve 13. As the valve and piston move to the left, the volume in chamber 78 formed between the cylinder 10 and the valve and piston assembly increases, while the cor responding volume in chamber 79 at the other end de'- creases. The drop in pressure at 78 induces fluid to flow via inlet port 80, valve annulus 81, labyrinth passage 82, annular valve chamber 75, piston port 74 and passage 83 to chamber 78. Fluid in chamber 79 is forced via valve port 84, passage 85, and port 72 into annular valve chamber 73. From thence it passes by passage 86 to annulus 87 and out through outlet 88.

0t the end of the stroke, the outlet port 88 is closed by the central valve land 89, whilst the inlet port is closed by the right hand end land 90 on valve 13. This effect constitutes a fluid lock and, although it need not be completely attained, it is essential that it be approached. When the piston 11 reverses and begins to move to the right, because of the fluid lock or near blockage of the inlet and outlet ports 80 and 88, respectively, the valve lags the piston movement instead of bouncing with it, as might occur if the outlet were at high pressure and connected with chamber 79 by 87, 86, 73, and 72. Also the pressure transient formed in chamber 78 by the initial right hand movement it piston 11 contributes to the valve lag.

As the piston 11 moves to the right, the piston port 72 communicates with valve chamber 75, and the increasing volume at 79 draws fluid from inlet port 80 via annulus 81 and passage 82 communicating with chamber 75. Similarly, piston port 74 connects with valve chamber 91, and the decreasing volume at 78 causes exhaust via 83, 74, chamber 91 and labyrinth passage 92, which communicates with annulus 87.

The reverse stroke from the right hand end is similar, except that the inlet port 80 is closed by central valve land 89, and the outlet port 88 is closed by the left hand end valve land 93. Valve lag in this case is aided by decrease in pressure at 78 and momentary increase at 79.

Whereas various embodiments of the invention have been shown, showing desirable features for'different circumstances, these same circumstances will dictate whether or not it is desirable to use, for example, gas cushioning, an unbalanced arrangement, early cut-off, etc. Addition ally, a self-contained vibrator motor may be made by the simple expedient of deleting the power takeoff shaft 12 and by fixing the body of the cylinder directly to the load.

It will therefore be appreciated that variations and modifications can be made without departing from the spirit and scope of the invention as defined by the following claims.

What we claim is:

1. A fluid convertor in the form of a motor comprising a double ended cylinder; a double acting piston slidable within said cylinder and dividing said cylinder into chambers at either end thereof; end pieces of a predetermined thickness on said piston and of a diameter equal to that of said cylinder; a portion of reduced diameter between said end pieces; inlet port and outlet port means disposed inwardly from the ends of said cylinder a distance at least equal to the thickness of each end piece; a cylindrical valve piece axially slidable upon said reduced portion of said piston; conduit means in said piston in the form of a separate passage extending from each end of said piston to a separate port on said reduced portion of said piston; conduit means in said valve piece alignable with said ports on said reduced portion of said piston; annular groove means on the exterior of said valve piece communicating with said conduit means in said valve piece and alignable with said inlet and outlet port means in said cylinder, thereby to efiect communication between said inlet port means and one of said chambers and between said outlet port means and the other of said chambers; and land means on said valve piece whereby, upon relative movement of said piston and said valve piece, said communication between said port means and said chambers may be successively blocked and reversed.

2. A system for converting the energy from fluid under pressure into mechanical power, comprising in combination: a cylindrical casing embodying, intermediate of the ends thereof, inlet port means and outlet port means therein, in substantially diametrically opposed location, one from the other; a double acting piston member slidably reciprocable within said casing, having substantially cylindrical flange portions at either end thereof, and a portion of reduced diameter extending therebetween, and embodying combined inlet and outlet ports and passages therein; and a cylindrical valve member coaxially mounted upon said reduced portion and adapted to move in relation thereto between the inner faces of said flange portions, said valve member having a plurality of land portions thereon adapted successively to block and to open said inlet port means and said outlet port means, said valve member embodying, on the outer periphery thereof, annular grooves, on the inner periphery thereof, annular passages in communication with said combined inlet and outlet ports and passages, between each said annular groove and one of said annular passages, labyrinth passages, and between each said annular groove and one of said inner faces of said flange portions, restricted labyrinth passages.

3. The system claimed in claim 2 in which at least one end of said piston member is in driving engagement with an output shaft extending through said casing in coaxial alignment with said reduced portion.

4. The system claimed in claim 2 and further comprising self-starting means whereby said inlet port means in said casing is at least partially communicable with one of said combined inlet and outlet ports and passages in said piston member at all times.

5. A system for converting the energy from fluid under pressure into mechanical power, comprising in combination: a cylindrical casing embodying an inlet port therein equidistantly disposed from the ends thereof and a pair of outlet ports therein equidistantly disposed from said ends and in diametrically opposed location from said inlet port; a double acting piston member slidably reciprocable within said casing, having substantially cylindrical flange portions at either end thereof, and a portion of reduced diameter extending therebetween, and embodying combined inlet and outlet ports and passages therein; and a cylindrical valve member co-axially mounted upon said reduced portion and adapted to move in relation thereto between the inner faces of said flange portions, said valve member having end land portions and a central land portion thereon, said central land portion being disposed intermediate of said end land portions and being adapted co-operably with said end land portions, successively to block and to open said inlet port and at least one of said outlet ports, said valve member embodying, on the outer periphery thereof, annular grooves on either side of said central land portion, on the inner periphery thereof, annular passages in communication with said combined inlet and outlet ports and passages, between each said annular groove and one of said annular passages, labyrinth passages, and between each said annular groove and one of said inner faces of said flange portions, restricted labyrinth passages.

6. The system'claimed in claim 5 in which said inlet port and said outlet ports are of like size and said central land portion is of a size sufiicient to block said inlet port completely.

7. The system claimed in claim 5 in which said inlet port is of restricted size with respect to that of said outlet ports and of said annular grooves on the outer periphery of said valve member.

8. The system claimed in claim 5 and further comprising self-starting means whereby said inlet port means in said casing is at least partially communicable with one of said combined inlet and outlet ports and passages in said piston member at all times.

9. The system claimed in claim 8 in which said selfstarting means is in the form of a bleed hole embodied in said central land portion and communicating said inlet port with one of said labyrinth passages in said valve member.

10. The system claimed in claim 8 in which said selfstarting means is in the form of a slight bevel on the face of said central land portion, whereby said inlet port is at least partially communicable with one of said annular grooves in said valve member at all times.

11. The system claimed in claim 5 in which said flange portions have shoulders extending from the outer faces thereof in axial alignment with said reduced portion, and said casing embodies corresponding cut-out portions at either end thereof.

12. The system claimed in claim 11 in which said end land portions on said valve member have shoulder portions extending therefrom, and said inner faces of said flange portions embody corresponding cut-out portions therein.

13. The system claimed in claim 5 in which said end land portions on said valve member have shoulder portions extending therefrom, and said inner faces of said flange portions embody corresponding cut-out portions therein.

References Cited in the file of this patent UNITED STATES PATENTS 109,167 Ambos Nov. 15, 1870 271,781 Brazelle Feb. 6, 1883 397,958 Barth Feb. 9, 1889 612,437 Rhodes Oct. 18, 1898 705,436 Pecoraro July 22, 1902 926,260 Klein June 29, 1909

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