US3074622A

US3074622A - Aerodynamic wave machine port lead edge modification for extended speed range

Info

Publication number: US3074622A
Application number: US18384A
Authority: US
Inventors: Berchtold Max
Original assignee: ITE Circuit Breaker Co
Current assignee: ITE Circuit Breaker Co
Priority date: 1960-03-29
Filing date: 1960-03-29
Publication date: 1963-01-22
Anticipated expiration: 1980-01-22

Description

Jan. 22, 1963 AERODYNAMIC WAVE MACHINE PORT LEAD EDGE ENG/NE '1T 5 #fm/fr Paar c 4/ al1/E L cya; I

LA aunar )0027/4 MODIFICATION FOR EXTENDED SPEED RANGE Filed March 29, 1960 3 Sheets-Shawl'.4 1

Jan. 22, 1963 M. BERcHToLD 3,074,622

AERODYNAMIC WAVE MACHINE PORT LEAD EDGE MODIFICATION FOR EXTENDED SPEED RANGE Filed March 29, 1960 3 Sheets-Sheet 2 ...FG-:5%- If-E: Eb.

HP /IVLE 7' 35%.. lunga-mann 3.f% ,egg/W. 4a .ll/.

M

7,45? HH/W.

INVENTOR. Max aina/170201.

BY y Zw-nn Awa, fase/651m i JaFff/v,

Jan. 22, 1963 M. ar-:RcHToLD 3,074,622

AERODYNAMIC WAVE MACHINE PORT LEAD EDGE MODIFICATION FOR EXTENDED SPEED RANGE IN1/mmm MA x afec/Wow' l I l I l l I l l 35% 0% 75% /aa% d/I United States Patent() AERODYNAMIC WAVE MACHINE PORT LEAD lllilgllg/IODIFICATION FOR EXTENDED SPEED Max Berchtold, Kusnacht, Switzerland, assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Mar. 29, 1960, Ser. No. 18,384 2 Claims. (Cl. 230-69) My invention relates to pressure exchangers used as superchargers for combustion engines and more particularly is directed to the configuration of the leading sections of the ports located in the high pressure cycle to minimize the detrimental effects of reflected waves created as a result of mis-timing during low speed operation.

With my novel configuration of the leading portion of the high pressure ports it is possible to `have a higher efficiency of the pressure exchanger over a wide speed range of operation and in particular permit a larger output of air and improved efficiency at low speeds.

The operation of an aerodynamic wave machine or pressure exchanger utilized in my instant invention is disclosed and illustrated in co-pending United States applications Serial Number 454,774, filed September 8, 1954 to Max Berchtold for Wave Engine now U.S. Patent 2,970,745 issued February 6, 1961; Serial Number 458,771, tiled September 28, 1954 to Max Berchtcld for Aerodynamic Wave Machine as a Supercharger for Reciprocating Engines now U.S. Patent 2,957,304 issued October 25, 1960; Serial Number 647,091, filed March 19, 1957 to Ernst Niederrnann for Reverse Cycle Aerodynamic Wave Machine now U.S. Patent 2,959,340 issued November 8, 1960; Serial Number 637,570 filed January 31, 1957 to Max Berchtold and Ernst Niedermann for Diesel Engine Supercharged by the Aerodynamic Wave Machine now abandoned; Serial Number 799,285, filed March 13, 1959 to Max 'Berchtold for Wide Speed Range Pressure Exchanger Supercharger now U.S. Patent 3,012,708 issued December l2, 1961 and Serial Number 742,601 led June 17, 1958 to Max Berchtold for Adjustable Stator Plate for Variable Speed Aerodynamic Wave Machine now U.S. Patent 3,011,487 issued December 5, 1961, all of which are assigned to the assignee of the instant application.

Many prior art constructions have been proposed -in order to increase the efficiency and maintain required mass-flow of the pressure exchanger when it is operated at speeds other than its design speed. One such method is to provide an angularly adjustable plate such as shown in aforementioned application Serial No. 742,601. Also prior arrangements have been suggested whereby the position of the edges of the ports have been changed in order to increase efficiency, such as disclosed in aforementioned applications, Serial Numbers 647,091 and 799,285.

In the operation of an aerodynamic wave machine, it is usually necessary to have a drive or control means to provide timing for the waves. If the aerodynamic wave machine is used as a supercharger, it is most advantageous to obtain the necessary power to drive the pressure exchanger from the reciprocating combustion engine. This can be achieved by any number of means, such as a belt drive, hydraulic drive, electrical drive, etc. The most economical and simple of these is the standard V belt drive. However, since most reciprocating combustion engines operate over a range of engine speed the pressure exchanger speed deviates at certain operating speeds from optimum conditions and efficiency may, therefore, be substantially decreased due to mis-timing of the waves.

ICC

Although lit is desirable to have the aerodynamic wave machine supercharger driven at a constant speed independent of the reciprocating engine speed, in practice, the speed, and thus the mass-flow requirements, of the reciprocating engine vary and hence the prior art fixed drive aerodynamic wave machine would not be eflicient through the entire speed range of the reciprocating engine.

However, with a simple and therefore desirable belt drive from the reciprocating engine to the aerodynamic wave machine, it is not possible to operate the pressure exchanger within the eflicient speed range. At low engine speed particularly it is desirable to maintain a high air manifold pressure which cannot be obtained at low speed of the pressure exchanger since the timing of the waves is upset to such an extent, that the required exhaust temperature exceeds the available exhaust temperature.

ln aforementioned copending application Serial No. 742,601, there is shown an arrangement whereby the variable speed drive from the combustion engine to the pressure exchanger is utilized and the pressure exchanger is provided with a continuously adjustable stator plate so that the ports are constantly being angularly repositioned to ensure proper timing at all speeds. This arrangement provides maximum efliciency over the speed range of the pressure exchanger. However, this is achieved at the sacrifice of a rather complicated mechani cal construction which not only adds expense to the pressure exchanger, but also increases the mechanical failures, inspection, maintenance and adjustments.

With my present invention, the eflciency is reduced over the range of speed operation when compared to the adjustable plate arrangement, but has a higher efiicency over low range of speed operation than other prior art wave machines or pressure exchangers.

My present invention is particularly directed to a pressure exchanger for supercharging an internal combustion engine in which it is desirable to drive the pressure exchanger by a simple belt or fixed gear rotor drive directly from the internal combustion engine, thereby requiring operation of the pressure exchanger over a wide speed range. l

I achieve this by a modification of the shape of the leading controlling edges of the high pressure ports.

During low speed operation of the internal combustion engine and the pressure exchanger themain compression Wave created at the leading controlling edge of the high pressure inlet port is mis-timed with regard to the leading controlling edge of the high pressure outlet port. This results in a very strong reflected wave being created in the rotor which has the effect of either slowing down, stopping or reversing the ilow of fluid from the high pressure inlet port into the rotor. However, if the leading controlling edge of the high pressure outlet port is properly shaped, the high pressure iluid created by the mis-timed wave is permitted to escape through the area formed by the stator and the rotor as a result of the flared portion ofthe leading edge. This desirable escape or leakage of the Ihigh pressure fluid through the llared controlling edge results in a substantially reduced magnitude of the reilection wave.

It is noted that my invention can be applied to either the lea-ding edge of the high pressure outlet port, or the leading edge of the high pressure inlet port or to both of the ports. The leading edge of the high pressure inlet port is Iflared out inorder to create a more. gradually increasing main compression wave which at the leading section of the inlet port will result in substantially reduced reflection waves specifically in the case of extreme mis-timing at low speed of the pressure exchanger. Thus when the modified edge of the high pressure inlet port is used in coniunction with the modifiedv edge of the high pressure outlet port, there is a very effective arrangement for reducing the deleterious effects of the reiiected waves.

It is noted that when both the inlet and the outlet ports have a gradual opening of the leading edge, the pressure exchanger has extremely desirable operation near the design speed. That is during normal operation (i.e. near design point) the gradual build up of pressure in the compression wave, due to the gradual opening of the high pressure inlet port matches the gradual opening of the high pressure inlet port and as a result thereof the overall losses due to the partial opening is maintained constant.

Accordingly, a primary object of my invention is to provide a novel arrangement whereby the modified controlling edges of the high pressure ports substantially reduces the magnitude of the re'ected waves created during mis-timing.

Another object of my invention is to provide an iinproved controlling edge for the high pressure ports to thereby reduce the reflection of the compression wave at low speed performances of the pressure exchanger. Another object of my invention is to provide a novel structural configuration for the leading edges of the high pressure ports to reduce the outflow at the high pressure inlet port and also reduce the in-liow from the high pressure outlet port.

Still a further object of my invention is to provide a pressure exchanger whereby the configuration of the controlling edges permits a larger output of air at low speeds at an improved efficiency to thereby permit a better matching of the pressure exchanger and the internal combustion engine supercharged and driven thereby.

These and other objects of my invention will be apparent from the following description when taken in connection with the drawings in which:

FIGURE 1 is a schematic representation of a pressure exchanger supercharging a combustion engine and shows a direct drive such as belt drive from the reciprocating combustion engine to the pressure exchanger.

FIGURE la is a schematic perspective view of a pressure exchanger having reverse cycle with two cycles per revolution. This figure illustrates the rotor and ports within the stationary stator plates.

FIGURE 2a is a partial schematic view of the rotor and ports showing the conditions of the iiuids in the high pressure position of the cycle with the rotor driven at 35% of maximum r.p.m.

FIGURE 2b is a partial schematic view of the rotor and ports showing the condition of the fluids in the high pressure portion of the cycle with the rotor driven at 75% of maximum r.p.m. which is design speed. This figure corresponds to the high pressure portion of FIG- URE 5.

FIGURE 3a is a view similar to FIGURE 2a but shows the condition within the rotor when the leading edge of the high pressure outlet port D is modied to flare out in accordance with my invention.

FIGURE 3b is a view similar to FIGURE 2b of the machine modified as noted in FIGURE 3a.

FIGUREAa is a view similar to FIGURES 2a and 3a but shows the condition within the rotor when the leading edge of both high pressure ports (inlet and outlet) are modied in configuration in accordance with my invention.

FIGURE 4b is a view similar to FIGURES 2b and 3b of the machine modified as noted in FIGURE 4a.

FIGURE 5 is a schematic developed View of the rotor and port showing the condition of the liuids in each section of the rotor having reverse cycle operation. rIhis view illustrates the cycle of operation at prior art design conditions and illustrates an ideal design cycle.

FIGURE 6 is a tabulation to compare eight conditions and show how my novel pressure exchanger compares with prior art pressure exchangers.

FIGURE 6a is a graphic illustration of the tabulation in FIGURE 6 plotting pressure exchanger air mass flow vs. reciprocating combustion engine 1'.p.rn. and illustrates the relationship for nine different conditions between the requirements of a reciprocating engine and that actually delivered by an aerodynamic wave machine used as a supercharger.

Referring to FIGURE l, there is shown a schematic representation of a pressure exchanger 10 having a low pressure inlet port B for fresh air, a low pressure outlet port A to exhaust the =hot gases, a high pressure outlet port D to supply compressed air through duct 12 to the combustion engine 11, and a high pressure inlet port C which supplies the pressure exchanger with high pressure exhaust gases from the combustion engine 11 fed through the duct 13. The drive shaft 14 of the combustion engine 11 has a pulley 16 and the drive shaft 15 of the pressure exchanger 10 has a pulley 17.

The direct drive from the combustion engine 11 to the rpressure exchanger 10 is achieved by the belt 18 which transmits shaft power from pulley 16 to pulley 17. The ratio of the `direct drive can be achieved by various size pulleys. Any other means well known in the art can be used for this drive purpose.

Thus referring first to FIGURES 1 and la, the rotor 30 of the pressure exchanger I@ is driven for rapid rotation about its axis by means such as a belt drive l from the combustion engine 11 placed over the pulley 17 of the rotor shaft 15. The manner in which the exhaust gases from the combustion engine are supplied to the pressure exchanger 10 and the manner in which the compressed air from the pressure exchanger 1% is supplied to the cornbustion engine 11 is illustrated and described in aforementioned Vcopending U.S. application Serial Number 458,771. The rotor 3f) has an outer shroud 33` and a plurality of channels or cells 35. The cold stationary stator plate 4f) is placed at one end of the rotor 36- and the hot stationary stator plate 41 is placed at the other end of the rotor 30 in the closest possible proximity thereto consistent with both high speed rotation required in the rotor as Well as variations due to expansion of the parts and still maintain the best possible fluid tight seal. The stationary stator plate 41 on the right side of the rotor 3f) is provided with high pressure inlet port C for the input of a first fluid at elevated pressure and temperature and a low pressure outlet port A for exhausting the yfirst fluid at approximately ambient pressure. Stationary stator plate 46' on the left of rotor 3f) is provided with a high pressure outlet port D for the output of a second fluid at elevated pressure, which tiuid is the compressed air supplied to the combustion engine 11, and low pressure inlet port B for the intake of the second fiuid at ambient pressure.

Since rotor 3d' of the pressure exchanger 10 is belt driven from the combustion engine 11 it rotates with a variable speed proportional to that of the combustion engine but as will hereinafter be more fully described our instant invention provides a novel configuration of the leading edges of the high pressure ports to reduce the undesirable effects of mis-timed waves.

As individual channels or cells of the rotor 30 of the prior art pressure exchanger move successively past opposite ports C and D and then A and B, the creation and propagation of the various waves as well as the pressure interchanges and interfaces which occur are demonstrated in a development View of FIGURE 5. A detailed analysis of the cycle of operation is set forth in aforementioned copending application Serial Number 454,774. It is noted that FIGURE 5 represents the ideal cycle of operation. Thus the pressure exchanger has been' designed for maximum efficiency at the rotor speed of FIGURE 5, i.e. design speed.

Within the high pressure State I the opening or leading

edges

5 and 6 of the high pressure inlet port C and high pressure outlet port D are physically related to each other and the closing or trailing

edges

7 and 8 are physically related to each other. 'Ihe cycle of operation is essentially independent ot the length of time during which the lluid remains at State II and there is no relation between the pair of ports C, D of the high pressure stage and the pair of ports A, B of the lower pressure stage.

FIGURE 5 illustrates an example of an ideal condition of the prior art in which there is complete high and low pressure scavenging of the pressure exchanger 10. The action of the Waves can also be studied in FIGURE 5 by cutting a narrow slot in a piece of paper to represent a typical channel or cell 35 and sliding this slot transversely down FIGURE 5. In the illustration the rst fluid, which represents the hot gas exhaust from the combustion engine 1I, is represented by the dotted area, and the second uid, which is the compressed air output of the pressure exchanger, r into the combustion engine l1, is represented by the unmarked area. The movement of the uid is indicated by the arrows.

The second uid can be at ambient pressure and is always present at the low pressure inlet port B, and the first fluid is always present at the high pressure inlet port C. The cells 35 in the rotor 30 are continuously moving past the ports A, B, C and D and the closed spaces between the ports in the stator plate 40 and the stator plate 41. Thus, for the purposes of description, the cycle of operation may start at any point. At zero degree rotation the second iluid is at rest at State IV in the rotor 30. The period of time that the second tluid is at rest during State IV depends only on structural conditions and does not affect the cycle of operation. When the channel has rotated approximately 10 its right end reaches the opening or leading edge 5, thereby permitting the rst fluid in high pressure inlet port C to impinge upon the medium pressure second fluid within the rotor 30. Since the total pressure in the high pressure inlet port C is higher than the pressure of the second fluid in the channel, the tirst uid which leaves the high pressure inlet port C impinges with a given velocity upon the second fluid within the channel and by this action compresses the second fluid and puts it in motion. The first particles of the second uid which are subjected to this impingement in turn push against adjacent particles and compress them, and also put these particles in motion. This mechanism creates a compression acceleration wave CA which travels faster than the second fluid now set in motion. The second uid ahead of the wave CA is still stationary, and thus at its State IV. Behind or upstream of the Wave CA both the compressed second uid and the iirst uid are in State I. Both iluids are at the same velocity and high pressure but divided by an interface identified as HPI.

When the channels have rotated approximately the left end will reach the opening or leading edge 6 in the stationary plate 40 of the high pressure outlet port D and the relationship of the opening edge 5 to the opening edge 6 is such that all of the second iluid in the cell is compressed. Thus only compressed second uid will be moved out into the high pressure outlet port D. When the channels have rotated approximately the right end is closed by the closing edge 8 of the high pressure inlet port C and no further particles of the rst lluid enters the channel. Hence, the last particles of the second lluid in the channels will expand down to a given medium pressure and thereafter the next adjacent medium pressure particles,'which are no longer being pushed through the channel, will expand and so on. This is the creation of an expansion deceleration wave ED which travels downstream through the channels and eiectively decreases both velocity and pressure. The pressure exchanger, aerodynamic wave machine 10 is designed so that as soon as the expansion deceleration wave ED reaches the left end of the channel the channel will have rotated 45 to thereby close ott the left end of the channel by the closing or trailing edge 7 in the stationary plate 40 of the high pressure outlet port D so that no first iluid at medium pressure' Will enter the high pressure outlet port or pickup port D.

It should be noted that if an aerodynamic wave machine 10 is designed for a specific pressure ratio such as illustrated in FIGURE 5 the opening or leading edge 5 of the high pressure inlet port or nozzle C is physically positioned with respect to the closing or trailing edge i of the high pressure outlet port D so that the high pressure interface HPI will arrive at the left end of the channel when the channel is rotated 45 and thereby closed ott by the closing edge 7 of the high pressure outlet port D and thereby prevent any iirst fluid, even though at high pressure, from entering the high pressure outlet port D.

Between approximately 45 and 60 rotation, as illustrated in FIGURE 5, i.e., after the channel has passed the high pressure outlet port D and high pressure inlet port C, but has not yet reached either the low pressure inlet port B or the low pressure outlet port A, the channel is closed at both ends by the stationary stator plate 40 and stationary stator plate 4l and the first uid is stationary in the channel at medium pressure. The length of time that the first fluid remains at this State II does not affect the cycle of operation.

When the channel has rotated approximately 60, as seen in the illustration of FIGURE 5, the right end of the channel is opened to the opening edge I of the low pressure outlet port A, which port is at an ambient pressure lower than the pressure in the channel. Thus, an expansion acceleration wave EA is created at the opening or leading edge 1 and is propagated 'downstream through the channel.

The pressure of the first uid ahead of the wave EA is at State II, whereas the pressure behind the wave EA is at the ambient pressure existing in the low pressure outlet port A, so that the exhaust or scavenging velocity will depend on the pressure drop through the Wave EA.

The aerodynamic wave machine l0 is designated so that as the expansion acceleration wave reaches the left hand end of the channel, the channel will be opened by the opening edge 2 of the low pressure inlet port B at approximately At this time the first uid in the channel is exposed at its left end to the second fluid start tlowing into the channel with the second uid replacing the first fluid, i.e., scavenging out the lirst uid'. This condition continues to exist until the channel has rotated approximately at which time the left end of the channel is closed oft by the closing edge 4 in the stationary stator plate 40 of the low pressure inlet port B. At this time an expansion deceleration wave ED is created at the closing or trailing edge 4, which wave travels downstream, thereby reducing the pressure of the second fluid to a pressure below ambient at State IV.

The machine is designed so that the right end of the cell is closed olf by the closing edge 3 of the low pressure outlet port A when the expansion deceleration wave ED reaches the right end. At this time the channel contains only the second fluid at a vacuum and is stationary, ijef, at State IV.

When the channel has rotated the complete reverse cycle operation noted above will repeat itself as illustrated in FIGURE 5 and -the same cycle of operation can be repeated for the remaining ports during the second 180 rotation.

In the description of FIGURE 5, it will be noted that the aerodynamic wave machine is operated under ideal conditions in which there is not only proper timing of the various wavesand'interfaces, but also the device operates at maximum etliciency. In the description thus far, it has been assumed that the aerodynamic wave machine is op,- erated at a fixed r.p.m., which r.p.m. enables the device to operate under near optimum conditions.

i It is desirable to have the pressure exchanger or aero-v dynamic wave machine 10` driven by the combustion engine 11 which it is to supercharge. Thus, for example, some shaft energy from the combustion engine 11, can be supplied to the aerodynamic wave machine 10` by utilizing a belt drive 18 with pulleys 16 and 17. However, as

7 will hereinafter be more iuliy explained in connection With FIGURES 2a, 2b, 3a 3b, 4a and 4b, the timing requirements and eiliciency of the machine will be considerably upset with variable rpm. of the combustion engine and pressure exchanger. Hence the pressure exchanger' will not be abie to satisfy the new mass i'low requirements of the combustion engine.

FIGURES 2a and 2b show the wave diagram of the high pressure stage of a prior art pressure exchanger when operated at 35% and 75% r.p.m. and in FIGURES 3a, 3b, 4a and 4b show the wave diagram of the high sure stage of a pressure exchanger with my invention.

FIGURES 2a, 3a, and 4a are at 75% rpm. so that an accurate comparison can be made. FIGURE 2b is, in fact, taken from the ideal cycle of FIGURE 5 and shows the compression acceleration Wave CA and expansion deceleration wave ED at design speed, i.e., 75 of maximum r.p.m. It will be noted that wave CA which originates at the leading edge 5 of the high pressure inlet port D terminates on the leading edge 6 of the high pressure outlet port D and the wave ED which originates on the closing or trailing edge 8 of the high pressure inlet port C terminates on the closing edge 7 of the high pressure outlet port D.

However, if the pressure exchanger is slowed down to of maximum r.p.rn. as seen in FIGURE 2a, waves CA and ED arrive at the stator plate it? ahead of the edges `6 and 7 respectively and, as illustrated, there wili be an undesirable back-ilow from the high pressure outlet port D back into the rotor near the closing edge 7.

The undesirable back-flow at 35% of maximum rpm. in FIGURE 2a is eliminated in my novel device as can best be seen by a comparison of FIGURE 2a with 3a and 4a.

As seen in the comparison of FIGURES 2a and 2b, the pressure exchanger, when operated from a simple belt or xed gear ratio drive, will have its r.p.m. varied, depending upon the speed of the combustion engine driving the pressure exchanger.

Although the pressure exchanger may be designed for a f that the compression acceleration wave originated at leadi ing edge 5 will terminate at leading edge 4 when the pressure exchanger is operated at design speeds. In the event that the rotor r.p.rn. is substantially reduced as for example, from 75% of its maximum r.p.m. down to 35% of its rpm., such as shown in the comparison of FIGURES 2b and 2c, then the compression acceleration wave at the leading edge 5 will be completely mistimed.

As seen in FIGURE 2b the mis-timed Wave CA will arrive at the stator ahead of the leading edge 6. This compression acceleration wave CA arrives too early at the high pressure outlet port D and caused a very strong reflected wave CD to be propagated through the rotor as seen in FIGURE 2a. Again, as seen by comparison of FIGURES 2a and 2b the reflected Wave CD exists during -design speed operation and terminates on the trailing edge 8 of the high pressure inlet port C.

However, when the rotor speed is substantially reduced this reflected wave CD will terminate ahead of the trailing edge 8, such as seen in FIGURE 2a. Since the reiiected wave CD has the effect of both compressing and modifying the velocity of the gases through which it will pass its early arrival at the high pressure inlet port C, could result in a reversal of uid flow as seen in FIG- URE 2a. That is, the uid behind the reilected wave CD will now ow into the high pressure inlet port C as indicated by the arrow 50.

Furthermore, the early arrival of the reilected wave CD at the high pressure inlet port C will result in a second reflected wave ED which will have the effect of both dropping the pressure and reducing the velocity of the uid through which it passes, hence when the second reflected wave ED arrives at the high pressure outlet port D, there will again be undesirable reversal of fluid from port D into rotor 30 such as indicated by arrow 5l.

The undesirable reversal of uid flowing between the high pressure inlet port C at 50 and the high pressure outlet port D at 51 due to mis-timing when the rotor speed is decreased has been dealt with in the prior art. As seen in aforementioned co-pending application Serial Number 799,285 the means to solve this reverse ow problem, consideration of changing the location of both the leading and trailing edges of high pressure outlet port D.

Although this prior art method has certain advantages for certain applications of a pressure exchanger, there are other situations in which the 1re-location of both the leading and trailing edge of the high pressure outlet port D is not completely satisfactory due to the fact that it could be substantially reduced during extremely low rpm. operation of the pressure exchanger rotor.

My instant invention can be used in combination or in place of the re-location of the edges of the high pres sure outlet port D. My instant invention, however, is specifically directed to the modification of the conguration of the leading edges of the ports in the high pressure position of the cycle.

In FIGURES 3a and 3b I have illustrated the conditions existing in the high pressure portion of the pressure exchanger cycle when the leading edge of the high pressure outlet port D is modified in accordance with my invention. It will be noted that the speed of the rotor in FIGURES 3a and 3b correspond to the speeds of the rotor illustrated in FIGURES 2a and 2b respectively.

Thus, it will be seen, in FIGURE 3a that the compression acceleration wave CA created at the leading edge 5 of the high pressure inlet port C will arrive at the stator 40 before the high pressure outlet port D is completely opened.

However, due to the flared surface 52 of the leading section of high pressure fluid ahead of the reflected wave CD will now be able to spill out into the high pressure outlet port D as illustrated by the arrow 53. That is,

f the wave CD, being a compression deceleration wave,

will compress the uid so that all fluid behind the wave is at higher pressure than the pressure ahead of the wave. Accordingly, in the embodiment seen in FIG- URE Za the fluid exisiting in the channels straddled by the waves CD and EA is at higher pressure than the fluid behind the Wave EA or in front of the wave CD. Therefore, by aring the surface 52 of the leading edge 6 of the high p-ressure outlet port D, as seen in FIG- URE 3a, the high pressure fluid straddled by the waves CD and EA will be permitted to spill out into the high pressure outlet port D. Furthermore, it will be noted that the Waves arriving at the extreme left-hand end of the rotor 30 will not initially terminate on the solid surface of the stator plate 40 and hence the magnitude of the reflected wave CD will be substantially reduced.

It will be noted that with a substantial reduction of the magnitude of the reflected wave CD such as seen in FIGURE 3a that this reflected wave will have less effect on the change in velocity than did the reflected wave CD in the conditions noted above in connection with FIGURE 2a. Hence there will now merely be a reduction flow of fluid from this port C into the rotor 30, as illustrated by the arrow 54.

In like manner the reflected wave ED will, of necessity, be of substantially reduced magnitude, .as compared to the 9 reflected Wave ED of FIGURE 2a. Hence the reflected wave ED will not result in a fluid flow reversal from the high pressure outlet port D into the rotor 30, but instead will merely cause a reduced flow into the high pressure outlet port D from the rotor 30, as illustrated by the arrow 55.

Thus, it will be seen that by providing a modified configuration of the leading section for the high pressure outlet port D, such as ared portion 52, it is possible to eliminate or at least substantially reduce the

undesirable flow reversal

50 and 51, as illustrated in FIGURE 2a and change this to a mere reduction in fluid flows 54 and 55 as illustrated in FIGURE 2b.

It is noted that the basic concept of my instant invention can be further adapted to the high pressure inlet port C to further improve the condition by reduction of

flow

54 and 55. To this end, I provide an arrangement as illustrated in FIGURES 4a and 4b whereby the leading section of the high pressure inlet port C, has a modified conguration, such as illustrated at 56. Thus in effect, when the channel of the rotor 30 is approaching the leading edge 5 of the high pressure inlet port C, it will beV opened at 51 due to the stepped configuration section 56v to permit the introduction of some fluid from the high` pressure inlet port C to the rotor 30.

, Due to the throttling effect created by the shape of the opening edge 5l of the port C, a compression acceleration wave CA of a lesser strength will initially be created in this channel. The strength lof this wave is less than the strength of the wave CA generated in the case of instantly full opening shown in FIGURES 2 and 3. Therefore, the strength of the reflected waves CD and EDv will be further reduced. f

As a result thereof, the reductions lof the ow from port C into the rotor -30 behindthe wave CD, and the reduction of flow behind the wave ED from the rotor 30 into the port D will be reduced to such an extent, that the speed of the rotor can be further reduced.

The shape of the opening'edge 56 of the high pressure gas inlet port C shown in FIGURES 4a and 4b allows the port to open only to a certain limited flow area. The shape is'so determined to provide a desired flow which in conjunction with the partial opening produces a first wave CA f lesser strength then in the case of the instant full opening.

With the normal leading edge half of the flow area is open at the time the rotor 30 has travelled half the distance of a blade partition. With the proposed shape however the channel only opens to a certain degree and remains essentially constant for about rotation of the rotor. Only then the flow into the channel becomes fully unrestricted and the wave assumes full strength. This arrangement permits an improved performance at 35% rotor speed, since the existence of a higher pressure in the channel opposite the ramp 52 prevents the undesirable outiiow at low speed.

At normal operating speed the loss of performance due to the gas escaping at the modified edge of the intake port is insignificant.

Thus, in essence I have provided a novel arrangement whereby the leading edge of the `high pressure outlet port D can have a modified configuration to result in a reduction of the magnitude of the reflected wave which minimizes the undesirable effect of mis-timed waves at low rotor speed.

Furthermore, the basic concept of my invention can vbe utilized at the leading edge of the high pressure inlet port C, to again minimize the undesirable effect of mis-timed waves at low rotor speed.

It is noted further, that my instant invention can be used in conjunction with or exclusive of the re-location of edges of the port to minimize the effect of mis-timed waves.

The tabulation of FIGURE 6 and the graphic illustration of FIGURE 6a will be used to summarize the char- Iacteristics of prior art devices compared to my device. As seen in the conditions of

curves

2, 3 and 4 of FIGURE 6a and the tabulation of FIGURE 6, a constant speed aerodynamic wave machine does not operate at a maximum efficiency while delivering the mass flow `to the combustion engine over the full operating lspeed range of the combustion engine. See aforementioned co-pending U.S. application Serial Number 637,570. In fact, this situation is still further aggravated by a variable speed` aerodynamic wave machine as seen for

curves

5, 6, 7 wherein the deviation from required mass flow of the combustion engine for variations in speed are even greater than in a constant speed aerodynamic wave machine. By using an adjustable stator plate (condition l), it is possible to reestablish timing of the main waves to keep maximum efiiciency so that there will be an approximately constant pressure output at the high pressure outlet port D as explained vand described in aforementioned copending U.S. application Serial Number 742,601. However, this method requires not only considerable additional expense but also necessitates continuous adjustments thereby increasing the possibility of malfunction.

Condition 8 is obtained with reduced size pick-up ports whereby `the

stator plates

40 and 41 are stationary and a direct fixed ratio drive between the internal combustion engine and the pressure exchanger is used. The delivered airflow at of the maximum speed is only slightly reduced to 98% of the flow with full size pick-up ports, with ideal timing conditions. However at 100% speed, maintaining the same engine exhaust gas temperature, the mistiming becomes more noticable and the mass flow reduces to about 95%. At 50% rotor speed the losses due to mis-timing cause a reduction in mass ow to about of the mass flow which is obtained with ideal wave timing. These conditions are `set forth in aforementioned copending application Serial Number 799,285 and shown in the tabulation of FIGURE 6 as condition 8 and are also graphically illustrated in curve S in FIGURE 6a. It will be noted that the arrangement illustrated as condition 8 and curve 8 is superior in performance to all other arrangements for 75% to 100% rotor r.p.m. except the adjustable plate illustrated as condition 1 and curve 1. However, the adjustable plate arrangement is a complicated mechanical construction which increases the cost, increases mechanical failure, requires more maintenance and mechanical adjustments. This condition has an efficiency which is slightly reduced over the range of speed operation when compared to the more expensive and complicated adjustable plate arrangement, but has a consistently higher efficiency over the 75 to 100% range of speed operation than all other prior art pressure exchangers even though there is no increase in either cost or mechanical complexity.

Condition 9 of tabulation in FIGURE 6 and curve 9 of FIGURE 6a, represent the advantages achieved with my instant invention. It will be noted that under some operating conditions it is desirable to continue to produce high torque for speeds below 40% of maximum engine speed. Thus with my instant invention the percent of required mass flow at 75% to 100% of r.p.m. may be slightly reduced but is maintained slightly above conditions such as 8 at 35% r.p.m.

Thus I have provided a novel configuration of the leading edges of the ports whereby the undesirable effects of the wave mis-timing can be minimized for low r.p.m. of the rotor to maintain a high pressure at the high pressure outlet port and also modify mass flow to substantially meet the requirements of a combustion engine.

Thus my invention is particularly adaptable to an aerodynamic Wave machine (pressure exchanger) supercharging a reciprocating combustion engine wherein the combustion engine has the requirement of a high torque over a wide speed range.

I claim:

1. A pressure exchanger being comprised of a rotor;

first and second stator plates positioned at opposite ends of said rotor, said first stator plate having a high pressure outlet port and said second stator plate having a high pressure inlet port, one of said stator plates also having a low pressure inlet port and the other of said stator plates also having a low pressure outlet port; said high pressure inlet port providing a path for the introduction of a fluid under high pressure into said rotor, and said high pressure outlet port being adapted t0 provide a path for the extraction of said Huid from said rotor subsequent to the compression thereof by said pressure exchanger; said high pressure outlet port having a leading and a trailing edge adjacent its associated rotor end; said leading edge of said high pressure outlet port being ared a predetermined amount, said flared leading edge being adapted to eliminate reverse fluid flow through said high pressure outlet port so as to optimize extraction of the compressed fluid therethrough; the leading edge of said high pressure inlet port having a stepped configuration, said stepped configuration having a leading and a trailing edge, the trailing edge of said stepped contiguration being the leading edge of said high pressure inlet port, the leading edge of said stepped configuration being a predetermined distance from the trailing edge and being adapted to reduce reverse uid ows at relatively low rotor operating speeds in order to optimize extraction of fluid from said high pressure outlet port.

2. A pressure exchanger comprising a rotor assembly mounted for rotation through a predetermined speed range, said rotor having a plurality of cells each extending longitudinally and substantially parallel with the rotor axis of rotation; first and second stator plates positioned at opposite ends of said rotor, each being substantially parallel to the plane of rotation of said rotor; said first stator plate having a high pressure inlet port and a low pressure outlet port; said ports being adapted to communicate with the cells of said rotor for introduction and extraction respectively of fluids in said rotor; said second stator plate having a high pressure outlet port and a loW pressure inlet port, said ports being adapted to communicate Withthe cells of said rotor for the extraction and introduction respectively of fluids in said rotor; the high pressure outlet port of said second stator plate having a leading and a trailing edge, said high pressure outlet port being positioned relative to the high pressure inlet port of said first stator plate so as to permit extraction of high pressure fluid introduced into said high pressure inlet port subsequent to introduction and compression of said fluid in said rotor cells; the leading edge of said high pressure outlet port being ared a predetermined amount, said flared leading edge being adapted to eliminate reverse ilow of sai-d compressed fluid in order to maximize extraction of said compressed fluid at said high pressure outlet port; the high pressure inlet port of said tirst stator plate having a leading and a trailing edge, the leading edge of said high pressure inlet port being positioned relative to the leading edge of said high pressure outlet port so that a point on said rotor passes the leading edge of said high prsesure inlet port a predetermined time prior to passing the. leading edge of said high pressure outlet port, the

leading edge of said high pressure inlet port having a stepped conguration, said stepped configuration having leading and a trailing edge, the trailing edge of said stepped configuration being the leading edge of said high pressure inlet port, the leading edge of said stepped conguration being a predetermined distance from the trailing edge, whereby a point on said rotor passes said stepped configuration leading edge prior to passing said stepped configuration trailing edge; the stepped configuration being adapted to reduce reverse flow of fluid at said high pressure inlet port in order to maximize extraction of compressed uid at said high pressure outlet port during lowspeed operation.

References Cited in the le of this patent UNITED STATES PATENTS 2,780,405 Jendrassik Feb. 5, 1957 2,836,346 lendrassik May 27, 1958 FOREIGN PATENTS 803,659 Great Britain Oct. 29, 1958 876,601 France Aug. 10,- 1942 OTHER REFERENCES Germany (Application Ia/46f, Hl2,826, Feb. 2, 1956.

Claims

1. A PRESSURE EXCHANGER BEING COMPRISED OF A ROTOR; FIRST AND SECOND STATOR PLATES POSITIONED AT OPPOSITE ENDS OF SAID ROTOR, SAID FIRST STATOR PLATE HAVING A HIGH PRESSURE OUTLET PORT AND SAID SECOND STATOR PLATE HAVING A HIGH PRESSURE INLET PORT, ONE OF SAID STATOR PLATES ALSO HAVING A LOW PRESSURE INLET PORT AND THE OTHER OF SAID STATOR PLATES ALSO HAVING A LOW PRESSURE OUTLET PORT; SAID HIGH PRESSURE INLET PORT PROVIDING A PATH FOR THE INTRODUCTION OF A FLUID UNDER HIGH PRESSURE INTO SAID ROTOR, AND SAID HIGH PRESSURE OUTLET PORT BEING ADAPTED TO PROVIDE A PATH FOR THE EXTRACTION OF SAID FLUID FROM SAID ROTOR SUBSEQUENT TO THE COMPRESSION THEREOF BY SAID PRESSURE EXCHANGER; SAID HIGH PRESSURE OUTLET PORT HAVING A LEADING AND A TRAILING EDGE ADJACENT ITS ASSOCIATED ROTOR END; SAID LEADING EDGE OF SAID HIGH PRESSURE OUTLET PORT BEING FLARED A PREDETERMINED AMOUNT, SAID FLARED LEADING EDGE BEING ADAPTED TO ELIMINATE REVERSE FLUID FLOW THROUGH SAID HIGH PRESSURE OUTLET PORT SO AS TO OPTIMIZE EXTRACTION OF THE COMPRESSED FLUID THERETHROUGH; THE LEADING EDGE OF SAID HIGH PRESSURE INLET PORT HAVING A STEPPED CONFIGURATION, SAID STEPPED CONFIGURATION HAVING A LEADING AND A TRAILING EDGE, THE TRAILING EDGE OF SAID STEPPED CONFIGURATION BEING THE LEADING EDGE OF SAID HIGH PRESSURE INLET PORT, THE LEADING EDGE OF SAID STEPPED CONFIGURATION BEING A PREDETERMINED DISTANCE FROM THE TRAILING EDGE AND BEING ADAPTED TO REDUCE REVERSE FLUID FLOWS AT RELATIVELY LOW ROTOR OPERATING SPEEDS IN ORDER TO OPTIMIZE EXTRACTION OF FLUID FROM SAID HIGH PRESSURE OUTLET PORT.