US3254483A

US3254483A - Mixing nozzle

Info

Publication number: US3254483A
Application number: US219255A
Authority: US
Inventors: Martin Herbert; Adolph Karl
Original assignee: J Eberspaecher GmbH and Co KG
Current assignee: Eberspaecher Climate Control Systems GmbH and Co KG
Priority date: 1961-08-24
Filing date: 1962-08-24
Publication date: 1966-06-07
Anticipated expiration: 1983-06-07
Also published as: GB1012174A

Description

2 Sheets-Sheet 1 igJ H. MARTIN ETAL MIXING NOZZLE June 7, 1966 Filed Aug. 24, 1962 .ujil'a/z June 7, 1966 H. MARTIN ETAL MIXING NOZZLE 2 Sheets-Sheet 2 Filed Aug. 24, 1962 ll 'lIiIlE-vllill United States Patent() 3,254,483 MlXING NOZZLE Herbert Martin and Karl Adolph, Esslingen (Neckar), Germany, assignors to J. Eberspacher, Esslingen (Neckar), Germany, a iirm of Germany Filed Aug. 24, 1962, Ser. No. 219,255 Claims priority, application Germany, Aug. 24, 1961,

E 21,578 Claims. (Cl. 60-30) The present invention relates to a mixing nozzle, particularly for the induction of air into the exhaust pipe of an internal combustion engine which for this purpose is provided with a constriction similar to a Laval nozzle and with an orifice for the passage of the air at the point of the smallest cross-sectional area of the constriction in the exhuast pipe.

Mixing nozzles of this type are being applied in exhaust pipes of internal combustion engines for mixing fresh air with the exhaust gases, for example, for the pur.- pose of cooling and afterburning the exhaust gases. There are also injectorlike mixing nozzles known in which the exhaust-gas pipe projects into a mixing cone.

The mixing ratio which is attainable with such mixing nozzles is only constant Within a very limited range. If the cross-sectional yarea of flow of the air and the size of the nozzle constriction are adjusted relative to each other in such a manner that a certain desired mixing ratio will be attained at a low gas velocity, an entirely different mixing ratio will occur at -a high gas velocity. For afterburning the exhaust gases it is, however, absolutely essential that the stoichiometric mixing ratio be constant under all operating conditions in order to insure a complete combustion of these gases.

It is a well-known fact that. the exhaust gases of internal combustion engines also function as carriers of sound impulses. The fresh-air intake openings of the known nozzle structures have the disadvantage that they may also act as outlets for noisy sound waves.

It is an object of the present invention to provide a mixing nozzle which permits the mixing ratio to be maintained constant under yany operating conditions. This object is attained according to the invention by providing the mixing nozzle with a displacement element, a conical part of which projects into the constriction of the nozzle and which is adjustable by means of a control rod so as to be slidable in a direction coaxial to the nozzle.

According to the invention, an annular orifice is formed between the displacement element and the wall of the mixing nozzle. By adjusting the conical displacement element, it is possible to increase or reduce the cross-sectional area of the nozzle orice. By employing a narrow annular orice, a low gas velocityl will be increased, while a high gas velocity will be reduced if the size of the an# nular orifice is increased. Thus, the amount of fresh air drawn in will always be in the proper proportion to the particular operating conditions.

The displacement element of the mixing nozzle is made of the aerodynamically most suitable tear shape with its tip pointing in the direction of flow. It also serves as a nonreilecting baille which prevents a resonance of the pipes and an inductive transmission of the sound into the air intake opening.

Another object of the invention is to provide a mixing nozzle of the most suitable shape by arranging the nozzle itself between two elbows in the exhaust pipe and by passing the control rod for the displacement element through the walls of the bent elbows which intersect the axis of the mixing nozzle. By this construction it is possible to omit any supporting means for the displacement element and the control rod at the inside of the exhaust pipe or the mixing nozzle and thus to avoid any obstructions which might interfere with the ffree flow of the exhaust gases and the air through the pipe or pipes.

According to one embodiment of the invention, the double-elbow pipe is preferably made of two molded shell sections which are provided with guide members for the control rod, for example, in the form of bushings, as integral parts thereof. These bushings may, of course, also be provided with suitable packings for sealing purposes and for facilitating the `sliding movement of the control rod therein.

Another feature of the invention consists in providing the elbow or adjacent parts of the exhaust pipe withsupporting means Afor the spring or lever elements which are connected to and act upon the control rod. If the mixing nozzle according to the invention is employed for the exhaust pipe of an internal combustion engine, the control rod may be positively connected to a control valve which is connected to the intake line of the engine. The mixing ratio is then controlled in accordance with the output of energy of the engine. If the engine is accelerated, the intake line contains a vacuum which is transmitted to the suction chamber of the control valve, whereby a piston therein is retracted which is connected to the control rod which, in turn, retracts the `displacement element from the mixing nozzle so that large amounts of exhaust gases can pass through the nozzle without being considerably accelerated. At lower speeds of the engine `and especially when the engine is idling, a compression spring in the control valve which is opposed to the suction therein acts upon the control rod so as to project the displacement element more or less into the constriction of the mixing nozzle, whereby the cross-sectional size of the annular orice is reduced and the exhaust gases passing through the nozzle are accelerated to such an extent that a large amount of fresh air is drawn in than at the time when the nozzle orice is free of the displacement element. In this manner it is possible to achieve what has often been tried unsuccessfully for the proper operation of exhaust gas cooling, neutralizing and afterburning device, namely, to adjust the mixing ratio in such a manner that the desired cooling, catalytic or afterburning effect will be fully attained under any operating conditions of the engine.

According to `another embodiment of the invention, the adjustment of the mixing nozzle may also be carried out automatically by mounting the displacement element in the mixing nozzle or in the mixing chamber in front of the open end of the exhaust pipe in such a manner that it partly projects into this open end and is maintained by suitable means in this position. Depending upon the prevailing amount of the exhaust gases and the resulting counterpressure, the displacement element is then maintained in a certain opening position so that the annular gap which is formed between the displacement element and the wall of the end of the exhaust pipe is adjusted in proportion to the amounts of the exhaust gases. Therefore, if the pressure of the exhaust gases upon the displacement element increases, the latter is forced out of Vthe open end of the exhaust pipe.

The pressure at which the displacement element is partly inserted into the open end of the exhaust pipe in the direction opposite to the ow of the exhaust gases may be produced by a spring which preferably has a curved characteristic.

3 A preferred embodiment of the invention consists in mounting the displacement element on a pivotable lever. The above-mentioned as well as additional features and advantages of the present invention will become more y clearly apparent from the following detailed description of several preferred embodiments thereof as illustrated in the accompanying drawings, in which- FIGURE 1 shows a diagrammatic illustration of the mixing nozzle according to the invention as applied to an exhaust pipe;

FIGURE 2 shows a diagrammatic illustration, partly in cross section, of an exhaust gas neutralizing apparatus for an internal combustion engine; while FIGURE 3 shows a modification of the mixing nozzle according to the invention.

Referring first to FIGURE 1 of the drawings, the exhaust line 1 of engine 1a is provided with a U-shaped double-elbow pipe 2 which is composed of two shell sections which are connected to each other within a plane lying within the axis of the pipe. Pipe 2 is designed at 2a in the form of a Laval nozzle. Shortly behind the narrowed point 2a of this nozzle, air inlet openings 3 are provided. According to the invention, a tear-shaped displacement element 4 is suspended at the center of the nozzle by means of a cable 5a which passes through the walls of the bent pipe to the outside and is secured at one end to a tension lever 6 which by means of a tension spring 7 which is connected to the wall of pipe 2 applies on cable 5a a tension in the direction of flow of the exhaust gases, as indicated by the arrows. The other end 5b of the cable is connected to the accelerator of the internal combustion engine, not shown. When the accelerator is depressed, the displacement element 4 is drawn out of the pipe constriction 2a with the result that the cross-sectional area of this constriction is increased because of the rearwardly converging shapeof the displacement element 4. If the tension on the accelerator or on the end 5b of the cable is decreased, the tension of spring 7 on lever 6 draws the displacement element 4 into the constriction 2a and thereby reduces the crosssectional area of the nozzle orifice. This position of element 4 is shown in FIGURE 1 in full lines, while its retracted position is indicated in dotted lines.

According to the modification of the invention as illustrated in FIGURE 2, the displacement element 9 is disposed within an ejector 8 and connected to a rod 10 which is positively connected to a piston rod 11a of a pressure valve 11. The combustion engine of a motor vehicle is indicated diagrammatically at 12, while 13 indicates an afterburning device fed with fuel and, if necessary, air through pipe 13a for heating residual combustible gases contained in the exhaust gases by means of an open flame to a temperature sufficient for them to burn in; catalytic afterburning device 14. Within the ejector `8, the exhaust gas line 15 is provided with a tubular enlargement 15a which contains the displacement element 9. The end of the exhaust gas line terminates into the nozzle 8a of the ejector which is surrounded by an outer annular housing 8b which is connected to the air intake pipe 16. Av part of the wall of this air intake pipe 16 is provided with perforations 16a and this perforated part is surrounded by a sound absorber which is filled with a sound-absorbent material. The suction chamber 11b of the pressure valve 11 is connected by a pipe line 17 to the front part of the intake line 18 of the combustion engine 112. If the engine is accelerated, a vacuum is produced in the lower part of the intake line 18 and transmitted to some extent t0 the suction chamber 11b, whereby piston 11e` is drawn back against the action of spring 11d and the conical part of the displacement element 9 is thus retracted yfrom the constricted end 15b of -the exhaust pipe. The operation of the ejector 8 is otherwise the same as that of the mixing nozzle according to FIGURE 1.

FIGURE 3 illustrates another modification of the invention, in which 19 indicate the exhaust pipe of engine 19b and 20 the mixing nozzle which at 20a surrounds the conical nozzlelike end 19a of the exhaust pipe and forms a mixing chamber with an air intake opening 21. The tear-shaped displacement element 22 is mounted on a lever 24 which, in turn, is mounted on a shaft 23, and its front part 22a projects in-to the open end 19a of the exhaust pipe. Under the tension of a spring 25 which is adjustab-ly connected to a bracket 26, lever 24 is normally pressed against a stop 27 yto maintain the displacement element 22 in a position in which an annular gap a forms the smallest adjustable nozzle orifice.

In order to prevent the displacement element from producing an excessive counterpressure in the mixing nozzle in the event that the guide members of this element should becomeI wedged, which might result in damage to the combustion engine, the invention further provides a bypass 28 which may 'be closed by a valve member 29 and connects a part of the exhaust pipe in front of the constriction with the part behind it. By means of a pressureresponsible element 30, the valve member may be opened when a certain pressure in the exhaust pipe is reached.

In order to prevent oscillation of the displacement element which m-ay be caused by vibrations of the exhaust column, the invention further provides the exhaust line with an acoustic suction resonator 31 which is preferably tuned to a frequency range of 50 to 200 cycles. In this manner it is possible to maintain the dynamic resistance of the mixing nozzle relatively small so that the fresh-air supply will not be reduced or shut off entirely because of a dynamic counterpressure.

Although our invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such embodiments, but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed our invention, what we claim is:

1. In an internal combustion engine exhaust pipe, said pipe including a first pipe section having a constricted portion terminating at its narrowest point in an opening directed downstreamward, a second pipe section having a part surrounded and spaced from said constricted portion and a continuation of such part in a downstream direction, said part having at least one intake opening to the outside for the admisison of air positioned laterally of said constricted portion, an elongated solid displacement element having its downstream end tapering su'bstantially to a point and having a rounded upstream end, and means supporting said element adjacent and extending partly into the constricted portion of the exhaust pipe for movement axially therein to vary the effective opening of the pipe.

2. A mixing nozzle as defined in claim 1, further comprising a neutralizing and afterburning device connected to said exhaust pipe behind said mixing nozzle.

3. A mixing nozzle as defined in claim 1, further comprising a sound absorber connected to said air intake opening.

4. A mixing nozzle as'defined in claim 1, in which said displacement element is disposed behind the open end of said constricted portion, and means for supporting and moving said element partly into and out of said open end, and means for limiting the extent to which said element may be moved into said open end to define an annular nozzle orice of la minimum size.

5. A mixing nozzle as defined in claim 4, yfurther comprising spring means for normally maintaining said element in the position in whch it defines said minimum orice size.

6. A mixing nozzle as defined in claim 4, in which said supporting means comprise a lever secured at one end to said element, means for pivoting said lever with said element about an axis laterally spaced from the axis of said element, and spring means` acting upon said lever for normally maintaining said element in the position in which it defines said minimum orice size.

7. A mixing nozzle as dened in claim 4, in which said exhaust pipe is connected by a by-pass to the mixing nozzle, a member for closing said by-pass, and a pressure- Y responsive element within said exhaust pipe for controlling said closing member to open said by-pass when the pressure in the exhaust pipe reaches a predetermined value.

8. A mixing nozzle as defined in claim 4, in which an acoustic suction resonator is provided Within said exhaust pipe, said resonator being turned to a frequency range of 50 to 200 cycles.

9. In a device as claimed in claim 1, means operatively connected to said element resiliently urging it in a direc' tion to reduce the eiective opening.

10. In a device as claimed in claim 1, a control valve having a cylinder and a piston in .said cylinder operatively connected to said element, and a pipe connecting said cylinder to the intake line of the combustion engine.

References Cited by the Examiner UNITED STATES PATENTS Worthington 60-30 Frazer 60--30 X Uhri et al. 60-30 X Gregg 230--112 Houdry. Bixler et al. 60-29 X Tryhorn et a1. 60-13 Houdry 60-30 Ridgway 60-30 Bozzola 60-13 FOREGN PATENTS France.

SAMUEL LEVINE, Primary Examiner.

JULIUS E. WEST, Examiner.

20 N. E. ABRAMS, A. S. ROSEN, Assistant Examiners.

Claims

1. IN AN INTERNAL COMBUSTION ENGINE EXHAUST PIPE, SAID PIPE INCLUDING A FIRST PIPE SECTION HAVING A CONSTRICTED PORTION TERMINATING AT ITS NARROWEST POINT IN AN OPENING DIRECTED DOWNSTREAMWARD, A SECOND PIPE SECTION HAVING A PART SURROUNDED AND SPACED FROM SAID CONSTRICTED PORTION AND A CONTINUATION OF SUCH PART IN A DOWNSTREAM DIRECTION, SAID PART HAVING AT LEAST ONE INTAKE OPENING TO THE OUTSIDE FOR THE ADMISSION OF AIR POSITIONED LATERALLY OF SAID CONSTRICTED PORTION, AN ELONGATED SOLID DISPLACEMENT ELEMENT HAVING ITS DOWNSTREAM END TAPERING SUBSTANTIALLY TO A POINT AND HAVING A ROUNDED UPSTREAM END, AND MEANS SUPPORTING SAID ELEMENT ADJACENT AND EXTENDING PARTLY INTO THE CONSTRICTED PORTION OF THE EXHAUST PIPE FOR MOVEMENT AXIALLY THEREIN TO VARY THE EFFECTIVE OPENING OF THE PIPE.