CA2042380A1 - Exhaust system for internal combustion engines - Google Patents

Abstract

Abstract:
Exhaust system for internal combustion engines whose pur-pose is to take advantage of the energy normally wasted by the engine,in order to create vacuum inside the pipes at the moment the exhaust valve opens. Vacuum which will suck out the gases from the cylinder, diminish engine temperature, reduce noises and improve engine efficiency. The elimination of all exhaust pressures is accomplished by means of a turbine, operating on the principle of pressure wave decomposition.

Description

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E~haust system for internal combùstion enGines. It iB well known the low efficiency of interral combustion engines. It iB
known too that part Or the energy is thrown away by the e~haust.
The present invention i~ that of an eIhaust system whose pur-pose is to take advantage of the energy wasted by the e~haust.
First let's assume that in a 4 stroke en~ine the eshauststroke combines waste of energy snd negative work interreri~g in efficiency and performance.
~ ctually what happens is that the time available for the engine to get rid of it~s e~haust gases is estremely short. Of oourse the time during which the eshaust valve opens is enough for the gases to e~it, but there must be no back-presure on the cylinder while it is on it~s up-tra~el ~hich is the exhaust stroke itself. That i8 ~hD the eshaust stroke always begins at the final stages Or the espansion stroke, and thus it i8 easy to conclude that the negative work is on one side while the loss is on the other.
Furthermore the time of self e~haustion or the energy which ex~els the eshaust gases from the cylinder varies according to acceleration or pressure on the cylinder while the time during which the eshaust valve opens varies according to engine rpm.
; The solution adopted in order to let an engine reach high rpm and consequently more pcwer output is by an earlier opening of e~haust valves which cuts the e~pansion stroke, but relieves the piston from back-pressure on it's up-travel.
~ he result of using such a technique is high fuel consump-tion and poor torque, balanced by high power output and rpm.
~ he question remains unsolved. If e~haust valve opens early, say 5^~ ~C some energy will be lost on the fi~al e~pansion stroke but the engine will be able to reach high rpm since the time available for exhaust will be longer-.On the other hand if exhauat valve opens near BC the espansion stroke will be com-p~eted but the engine will face heavy piston back-pressure at high rpm and thus poor horsepower output.
Another factor which limits performance in I.C. engines is the e~haust back-pressure, which controls the e~haust flow con-stricting it in order to smootb engine operation.
I.et's not forget the major enemy the atmospheric pressure.

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r 204 2~380 The object of the present invention ie to provide a meana of utilizin~ the ener~y wa~ted in order to perrorm a new and useful role in internal combustior engines not using eYhaust driven turbo-chargers.
The purpose of the present invention i8 to take advantage of the ener~y wa~ted and use it to dimlnish to a minimum level the negative ~ork and the losse~ occuring on e~haust stroke.
Yet another object of the present invention is to provide a means of both controlling the flow and fighting atmospheric lC pressure, eliminating the need for e~haust back-pressure while damping noi~es.
Among the several benefits of using such a system it can be said that the e~haust back-pressure will be eliminated due to the new constriction-free means of controlling the flow. The 1~ early opening of e~haust valves will be forgotten because back-pressure and atmospheric pressure ~ill not hinder exhaust flow anymore.
In addition the vacuum produced in the final stages of e~-haust stroke ~ill be greater and continuous all through the rpm band. This will benefit strongly the scavenging effect during overlap, making possible smaller time for this low efficiency task. As the extra vacuum will be continuous and there will be no more back-pressure pile-up as engine acceleration and speed increases,it is possible for the compresGion ratio to be raise~
The volume of residual e~haust gases left on the clearance will be smaller and the charge temperature consequently lo~er, de-creasing the ocurrence of pre-ignition and detonation while i~-proving volumetric efficienc~.
~he system comprises a turbine which i8 responsible for the ener2y transformatior. It works connected to the e~it end of the e~haust pipes (tubes) serving each cylinder of the engine.
The channels of the turbine work 8S a movable e~tension of the pipes, receiving pulses and creating vacuum by pressure wave decomposition. The only e~ception is for the one cylinder engine ~here the turbine channels cannot share different pipes d thus it i9 a different operatior..
~he most efficient eIhaust systems use single pipe per cyl--~ inder because it is important to direct the blast of the :"
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exhaust throu&h ~ tube in order to create v~cuu~, ~hich will suck out the remaining ~a~es in th~ cylinder. The drawback Or single pipe per cylinder is that the positive pulse can be con-~erted into a negsti~e one (oposite direction) ~hich sometimes hits the po~iti~e and block~ the elimination Or exhaust gases.
Furthermore single pipe per ¢ylinder must be tuned according to the rpm at which it will work. Outside that range the effect will be negati~e, making engine operation troublesome, The present invention proposeQ a method where the exhau~t will be tuned to the maximum acceleration desired no matter what the rpm, and for other situations the efficiency will be diminishe~ but never becoming negati~e.
~ unin~ of sin~le pipe per cylinder e~haust system is accom-plished by pipe lenght~ The tuning of the new e~haust system 1, differs from that of ordinary eshaust systems. First of all the cross section area transverse to the flow (here called C.S.A.) must be kept unchanged all through the system from exhaust port to the end of the turbine channels. This is important since the energy will be taken mainly from the gases speed and any en-2G largement or obstruction represents loss. The curves on thepipes must be as open as possible and always near the cylinder, avoiding those near the turbine except if they are projected against the turbine blades in order to help it-s dri~ing.
The pipes must be arranged so that they ~ork on identical temperatures because it's internal temperature affects the tuning. The lenght of the pipes depends upon the ma~imum accel-eration desired with both engine and pipes hot. The ~olume inside each pipe will be apro~imately c to 3 times that Or the cylinder.
3C As previously mentioned the pipe leng2.t tuning depends on it's internal temperature but other factors must be ta~en into account such as the turbine resistance to gas flow, i.e.whether it is driven by the crank~haft or by the exhaust jets or if the system comprises a catalytic con~erter or mufflers etc.
T:.e sum of C.S.A. for each exhaust pipe of the en~ine must be equal to the sum of C.S.~. for each turbine channel. As tne number of channels must be at least double that of pipes con-~ nected to it, the C.S.A. of the cbannel in this case ~ill .~ :

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be half that of the pipe.
~ he e~haust valve a~ described above need not be opened early in order to achieve high engine rpm and power output.
The overlap time will be narrower not only by oompression ratio rise, but by a contiDuous and steady e~haust generated vacuum.
The inlet valve closin~ can be retarded and this will benefit torque at high speed whithout affecting engine behavior at 10H
speed (dependin~ of course on the intake manifolds layout).
The turbine rpm is crucial and must be kept to a minimum aocording to the operation of the engine. For calculating the minimum rpm of the turbine for a given situation these things must be considered: the engine rpm, the pipe lenght, and the channel lenght which are the most important among others. For instance let' 8 take a 6 cylinder engine with 6 pipe end~ con-nected to a 12 channel turbine, the engine is running at 3,000 rpm at full throtle. The pipe is 1.6 meter in lenght while the channel i8 20 cm. In this case we have 1 e~haust pulse e~ery 12CQ of crankshaft revolution. ~s the ohannel lenght is 1/8 of the pipe lenght it would be necessary 8/6 of turbine re~olution ~0 to cover the pipe lenght every 120Q of crank~haft revolution.
So at 3,000 rpm the turbine should be spinning at aproximately 12,000 rpm. The general formula for calculating the minimum rpm of the turbine is: TR = ER ~ pl/cl ~ ?
NP
where E~ - the engine rpm TR - the turbine rpm pl~and cl - pipe lenght and channel lenght ~? - number of pipe ends connected to the t~rbine ? - to be determined by tests This formula of course is for a rough oalculation of the minimum turbine rpm and it doesn't take into account all the ~ariable elements for a precise calculation such as accelera-tion. So it ~erves to ilustrate the relationship between dimen-sions for the e~haust system, while establishing a minimum basis of turbine rpm which only real tests o~ the ~arious kinds of en&ine can demonstrate.
The pipes must be arranged so that where it is connected with the turbine, the flow order or firing order de~cribes a ~. :

204~3~30 T~ / "~ , 5 sequential circular movomcnt in t}le ua~c directior, as that Or the turbine. A lubricating ~ystem iB neces~ary for the bearings of the turbine.
In order to improve the ener~y e~change of the turbine (pressure x ~acuum) the pipes can be di~ided 80 that the pipe end connections with the turbine will be twice as many and the frequency of pul~eR on the turbine ~ill double, making possible the use of smaller turbine channel or lower turbine rpm. This solution somehow creates a difficulty in manufacturing sinoe the number of turbine blades will double alQo. It can be useful for bi-cylindrical engines.
The best option for the variable operation car engine is to connect the turbine to the crankshaft by a shaft so that the turbine will rotate in a ratio determined by the engine rpm. It is important to keep the turbine running during deceleration to a~oid engine malfunctioning caused by uncontrolled gas flow at sucb conditions.
As the speed of the eshaust will incrsase, the heat con-tained on the gases will be carried quickly from the valve port to the turbine where it will concentrate. As a result the tem-perature in the e~haust valves and cylinders will decrease but the latter will be partially compensated by the delayed opening of e~haust valves.
The drawings on the accompanying sheets represents the in-vention and it's embodiments which are as follows: Fig. 1 i8 alateral view of the system showing the pipes(l) which e~tends from the val~e ports to the connection pipe ~ turbine(2), the turbine case(3), and the driving shaft(4), Fi~. 2 i6 a lateral perspective view of the turbine,sbo~ing 3C it~s blades(5), the channels(6) and the shaft(7). The reference numbers 8 and 9 shows the inlet and outlet of the channel which can be e~tended if necessary.
Fig. 3 shows the pipe ends which are to be connected to the turbine. Thi6 piece can be twisted in order to direot the jets against turbine blades so as to help it's driving. The connec-tion ~ith tbe turbine forms a ring~10)~ and must be as close as possible to the channels.
Fig. 4 is a cutaway ~iew of the system and shows the shaft ~ PCr~R ,, 2~ 4C~,~3~03 ~L 5 (ll) Or the turbine, it'~ bearlng~(l2) and the driving shart (13) which ~ill be connected to the crankshaft. The joints(l4) of the driving shaft transmit power through angles and elimi-nates vibrations. The turbine blades(l5) must work very close to the case(l6) 80 a to svoid undue pas~ages of air, To con-nect the system with it ' 9 further embodiments it will be neces-sary a manifold(l7).
Fig. 5 i~ a detsiled ~iew of the driving shaft joint which consist~ of a spring(l8).
Fig. 6 is a schematic diagram of flow in ordinary exhaust systems, showing how the gases are exhausted from the beginning of the exhaust stroke (usually 50Q bbdc) until 50Q after bottom (dead) center. The vertical lines inside the pipes are the re-presentation of pressure at that point, while the horizontals under each pipe represent~ the speed. The abrupt variation in speed and pressure on the first pipe is the sound wave.
Fig. 7 is the same diagram of flow for the invention, ~here the gases will not face back-pre~sure and consequently will be carried much faster and efficiently. It can be seen the sound wave being damped on the first pipe by simply traveling through a very low pressure medium. The efficiency Or the sound damping will be near to that of the exhaust. As the exhaust will be tuned for the maximum acceleration desired, the maximum vacuum inside the pipes ~ill be achie~ed at such conditions, and so the sound da~ping will be be~t at the exact point where noises will be higher. It can be seen in Fig. 7 that when the high-speed gase6 hit the turbine they will be braked, and the resul-tant pressure wa~e must not reach the cylinder Hhile the valve is oper Fig. ~ is a graphic of pressure ~ lenght which e~plain~ the principles of pressure wave decomposition. The pipe(2C) and the channels(24) only demonstrate where is the connection Or pipes ~itb the channels and have no other purpose except this. The pressure ~a~e(l~) is that which hits the turbine and have to be deoomposed in order to generate vacuum. The waves number (21) and (22) could be produced by the short channel but the higher and more efficient was made by a turbine with a higher ratio of channels to pipe end connections. To produce a high efficienc~

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wave (23) wit~ ~ low rstio of chsnnelu to pipe end conneotions, it would be necessary a lon~ ohannel and oon~equently a hea~ier turbine. The vsouum waves~25) were produoed by the wares(21,22) snd will be thrown into the ne~t pipe~ to receive eshaust gen-erated pressure wa~e~.

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Claims (5)

Claims:

1- Exhaust system for internal combustion engines,comprising a turbine which is connected to the exit end of the exhaust pipes, where the said pipes work for each cylinder of the en-gine, being in a number equal to them.

2- Exhaust system for internal combustion engines, as set forth in claim 1, comprising a turbine which is divided into channels which work as movable extensions of the pipes, being the number of these channels at least double that of the pipe ends connected to them, and being the number of pipe ends equal to that of the cylinders or double that number if the pipes divide before connecting to the turbine.

3- Exhaust system for internal combustion engines, as set forth in claim 1 and 2, comprising a rotating turbine working inside it's case which has the shape of a volcano, being this case composed of 2 openings: the smaller one or the inlet where the exit end of the pipes are connected to the channels, and the larger one or outlet where the exhaust gases are freed to the atmosphere or further embodiments of the system.

4- Exhaust system for internal combustion engines, as set forth in claim 1 through 3, comprising a turbine which is a rotating wheel whose outer surface or circumference is covered with the channels working inside and very close to it's case, and where the rotational movement is provided by a shaft which passes through it's center, being this shaft the rotational structure of the turbine which can be connected to the crank-shaft in order to determine it's correct rpm.

5- Exhaust system for internal combustion engines, as set forth in claim 1 through 4, comprising a turbine whose connec-tion with the pipes has the shape of a ring, being this ring radialy divided so as to fit the exit end of the pipes (if seen from the turbine), or the inlet of the channels (if seen from the pipes), and being the vacant area in the center of the said ring, the space for the turbine shaft to extend to it's struc-ture.