DE2910273C2 - Internal combustion engine - Google Patents

Description

30th

The invention relates to an internal combustion engine according to the preamble of claim 1. Such is known from US Pat. No. 1,788,076

Internal combustion engines still require special attention with regard to two problem areas, namely once in terms of reducing the pollutant content in the exhaust gases, especially the Content of hydrocarbons, carbon monoxide «0 and nitrogen oxides, and on the other hand with regard to the thermal efficiency.

To reduce the proportion of pollutants in the exhaust gases of an internal combustion engine, it is known to reduce the HC, CO and NOx proportions in the exhaust gas at the same time by using a lean air / fuel mixture for the combustion. Furthermore, it is known to recirculate a large proportion of the exhaust gas into the intake system of the engine, with which above all the NO _x proportions can be reduced. Both procedures, however, have the disadvantage that the combustion rate of the air / fuel mixture is low and a high thermal efficiency cannot be achieved because the flame propagation speed in such a mixture is very low. As a result, the machine does not perform well. If you want to use a gas mixture of the aforementioned type in an internal combustion engine, then it is necessary to increase the thermal efficiency above all to increase the flame propagation speed.

The internal combustion engine known from US Pat. No. 1,788,076 does not do justice to this goal. Is with her the volume of the storage chamber as large as the stroke volume. The during the compression stroke in The fresh fuel gas mixture pressed in is actively cooled in it. The aim of this measure is to prevent knocking. Due to the pressure reduction caused by the cooling, eddies of the one flowing back into the combustion chamber at the beginning of the compression stroke of the subsequent work cycle Hardly produce gas.

From DE-OS 23 01 066 an internal combustion engine is known which has an auxiliary chamber in the cylinder head has relatively small volume in which the electrodes of a spark plug are arranged. Help? chamber is connected to the combustion chamber through a small hole. One leads into the auxiliary chamber Partial length of the intake duct extending parallel to the exhaust duct, over which relative to a HDfs carburetor rich gas mixture is supplied. The auxiliary chamber can be locked against its intake duct by an auxiliary valve, which is comparable in its function to the (main) inlet valve leading into the combustion chamber The combustion is initiated in the auxiliary chamber, but not the auxiliary combustion chamber Storage chamber is the aim of the arrangement is to build up a stratified charge in the combustion chamber.

The invention is based on the object of specifying an internal combustion engine which, with regard to the Flame propagation speed is further improved

This object is achieved by the characterizing features of claim 1 and further developments of the invention are the subject of the subclaims. According to the present invention is a Heat exchange area of the storage chamber located near the outlet channel of the machine, so that a Heating of the gases in the storage chamber can take place from the outlet channel. As a result of the Heat transferred to the outlet channel to the storage chamber is the movement of the fuel molecules in the Suction gas, which is temporarily stored in the storage chamber, and the atomization and evaporation of the Fuel there increased so that the fuel can be ignited very easily. In addition, a Pressure drop of the buffered in the storage xioimer Suction gas, which would be feared by cooling, can be avoided. It even becomes the Pressure in the storage chamber increased due to the heating of the temporarily stored suction gas, see above that there is a very sharp gas jet, which when the valve is opened between the storage chamber and the combustion chamber pours into the combustion chamber, causing a strong vortex movement there will.

The invention will be explained in more detail below with reference to the drawings. It shows

F i g. 1 shows a longitudinal section through a first embodiment;

FIG. 2 shows a section along the line H-II of FIG. 1;

F i g. 3 shows a longitudinal section through a second embodiment;

F i g. 4 shows a section along the line IV-IV in FIG. 3;

F i g. 5 shows a diagram of the valve opening times of the two exemplary embodiments a and

6 and 7 enlarged sectional views of various Embodiments of storage chambers.

Let first be F i g. 1 considered. A cylinder block 1 with a cylinder bore 2 is shown which a cylinder head 3 with a recess 4 facing the cylinder block 1 is attached. In the A working piston 7 is arranged in the usual manner in the cylinder bore 2. The in the cylinder bore 2 of the Recess 4 and the piston 7 delimited space

forms a combustion chamber 5. The combustion chamber 5 stands in with an inlet channel (not shown in FIG. 1) Link. The inlet duct is connected to a fuel supply device, such as a (not shown) carburetor connected. In the cylinder head, an inlet valve 11 (Fig.2) is arranged, which the Separates the inlet duct from the combustion chamber 5 and synchronously with the movement of a crankshaft (not shown) is driven to lift off from its valve seat 13 to fuel gas mixture through to let the inlet duct into the combustion chamber 5. With a "fuel gas mixture" is not just a common one Air / fuel mixture, but also a lean one Air / fuel mixture and a mixture with recirculated Referred to as exhaust gas

The combustion chamber 5 is also connected to an outlet channel 15 via an outlet valve 17. That Exhaust valve 17 has a valve stem 19 which extends through the cylinder head 3 to the outside and is pressed outward by a helical compression spring 21 supported on the cylinder head 3 in order to to press the valve 17 onto a valve seat 23 and thereby the combustion chamber 5 against the discharge 3 duct 15 complete. The valve stem 19 is synchronized with the movement of the crankshaft, not shown a rocker arm 25 is moved. Furthermore, there is a spark plug 27, the electrodes 27a of which are in the Combustion chamber 5 protrude.

A cavity 31 is formed in the cylinder head 3, in which a valve insert 33 with a valve 37 is arranged. In the valve insert 33 is axially a narrow bore introduced in which the valve stem 35 of the valve 37 is guided. A valve seat 336 on the valve insert 33 is assigned to the plate of the valve 37 The upper end of the valve stem 35 is pressed upwards by a helical compression spring 39 around the Press valve 37 onto valve seat 336. The upper end of the valve stem 35 is supported by a rocker arm 41 moved synchronously with the rotation of the crankshaft, not shown, The timing of this synchronism will be explained later

A long channel 43 of uniform cross-section, which can be round or rectangular, is formed in the cylinder head 3. This channel is formed when the cylinder head 3 is cast. One end 43a of this channel 43 opens above the valve 37 into a space in the valve insert 33. The other end 43b of the channel 43 opens on an outer wall of the cylinder head 3 The long channel 43 and the chamber 45 together form a gas storage chamber 47 which can be closed off from the combustion chamber by the valve 37 and in which the fuel gas mixture is moved back and forth. The channel 43 of this gas reservoir 47 runs essentially parallel to the outlet channel 15 and is arranged and designed so that the heat of the exhaust gas flowing through the outlet channel 15 can be transferred through the cylinder head 3 to the channel 43, whereby the fuel gas mixture located therein is heated will. It thus forms a heat exchange area of the storage chamber 47.

Between the valve 37 of the storage chamber 47 and the combustion chamber 5 there is a small one in the cylinder head A cavity is formed, in whose end facing the combustion chamber 5 a cap 49 is inserted. the Cap 49 has a cylindrical section 49a and an adjoining hemispherical one Section 496 on. One or more nozzle openings 49c are formed in the latter section in FIG. 1 is only one nozzle opening 49c is present. When the valve 37 is open, then that flows in the storage chamber 4? Cached fuel gas mixture through the nozzles 49c into the combustion chamber 5. It is advantageous if at least one of these nozzle openings 49c is arranged in this way is that the gas jet emerging from it creates a vortex that forms the electrodes 27a of the spark plug 27 so that a fresh fuel gas mixture is supplied to it and thus the ignition is facilitated. It is also advantageous to choose the size and the directions of the other nozzle openings 49c so that a unidirectional vortex movement or approximately uniform turbulence in the entire combustion chamber 5 result.

The second embodiment is described below with reference to FIGS. 3 and 4 explains this second Embodiment differs from the first in the arrangement of the inlet valve, the outlet valve, the inlet channel and the outlet channel, the storage chamber and the arrangement of the spark plug. Furthermore, the second embodiment differs from the first in the type of storage chamber. The valves are controlled in the same way as in FIG. 1, so that their explanation is omitted can be. In the F i g. 1 to 4, the same parts are provided with the same reference numerals. It should be emphasized, however that, although the inlet channel 9 in FIGS. 1 and 2, the structure of the inlet channel is not shown in FIG The inlet valve 11 has already been explained in detail with reference to the first exemplary embodiment is driven synchronously by the crankshaft via the valve stem 51. A helical compression spring 53 pushes the valve 11 into the closed position. The drive takes place via a rocker arm 55.

According to FIGS. 3 and 4, a long channel 43 'of uniform, for example circular or rectangular cross-section is introduced into the cylinder head 3 by machining.One end 43'a of the channel 43' opens above the valve 37 into a small chamber in the valve insert 33 The other end 43'b of the channel 43 'opens on the outer wall of the cylinder head 3. There, this channel 43' is closed by a screw 48 screwed into it. In this way, a closed storage chamber 47 'is formed for the temporary intermediate storage of fuel gas, which, since it runs near the outlet channel 15 and is heated by the hot exhaust gases through the cylinder head 3, in its entirety also represents a heat exchanger 43'

The timing of the valve actuation by the crankshaft is discussed below with reference to FIG. 5 will be explained. In Fig. 5, the crank angle θ of the crankshaft is plotted on the abscissa, while the opening widths of inlet valve 11, outlet valve 17 and valve 37 of the storage chamber (hereinafter referred to as auxiliary valve) are plotted on the ordinate sr.d, from the former with the line /, from the second with the line E and the last-mentioned valve with the line S. Immediately before reaching the top dead center p'DQ) of the piston 7, the intake valve 11 opens. The intake stroke now begins. After the first top dead center (TDC \) is reached, the exhaust valve 17 is closed. A combustible gas mixture is now sucked into the combustion chamber 5. After the piston has reached the

has reached bottom dead center for the first time (BDQ), the compression stroke begins, in which the inlet valve 11 is closed. Immediately thereafter, the gas storage valve 37 is opened since the fuel gas mixture, which is temporarily stored in the storage chamber 47 (Fig. 1) or 47 '(Fig. 3), has a higher pressure than the compressed fuel gas mixture in the combustion chamber for reasons to be explained later 5, a gas flow pours through the nozzle openings 49c of the cap 49 into the combustion chamber 5, ι ο when the auxiliary valve 37 is opened. One of the gas jets emerging from the nozzle openings 49c washes around the electrodes 27a of the spark plug 27. Due to the aforementioned gas jets, approximately the same turbulence is generated in the entire interior of the combustion chamber 5. It is advantageous if the cross-sectional area of the nozzle openings 49c of the cap 49 is smaller than the cross-section the storage chamber 47 or 47 'at the channel 43 or 43'. This results in a greater intensity of the exiting gas jets.

Since the storage chamber 47 or 47 'is arranged near the outlet channel 15 and therefore there is a heat transfer from the exhaust gases to the temporarily stored fuel gas mixture, the atomization takes place and evaporation of the fuel in the temporarily stored fuel gas mixture is improved. By heating the temporarily stored fuel gas mixture the pressure in the storage chamber 47 increases at the same time. A cooling of the temporarily stored gas the contact with the walls of the storage chamber 47 or 47 'is therefore not to be feared.

In the case of the FIGS. 1 and 2 illustrated first embodiment of the invention flows under high Pressurized fuel gas mixture in the heat exchange area 43, which has a smaller cross section than the chamber 45, at high speed when it is fed to the chamber 45. Because of the mechanical vibration effect, which is caused by the flow, results in a further mixing of the gas. At the same time, the fuel particles in the fuel gas mixture are further reduced A reduction in the size of the fuel particles leads to an increase in the total surface area of all fuel particles. Furthermore, the fuel particles are in passed a region in which the vapor pressure of the fuel gas mixture is small. As a result, the Atomization (atomization) of the fuel improved

In the second embodiment shown in FIGS. 3 and 4, the fuel gas ^{mixture Μ} also flows in the storage chamber 47 ', one end of which is closed by the screw 48. This flow is caused by the pressure change that occurs when the auxiliary valve 37 is open.This pressure change is shared by the storage chamber 47 'with which is enclosed by the cylinder head 3 and the screw 48. As a result, the atomization and evaporation of the fuel particles in the fuel gas mixture is improved and the fuel is mixed even further with air

As mentioned above, the atomization and evaporation of the fuel gas mixture is promoted by heating it up. The pressure of the temporarily stored fuel gas mixture is kept at a high level by the heating. The diameter see the fuel gas mixture, the atomization and Evaporation of the fuel will be further improved when the fuel gas mixture through the Wärmetauschbe rich 43 or 43 'of the storage chamber 47 or 47' towards and flows here. Accordingly, when the fuel gas mixture under high pressure from the storage chamber 47 or 47 'flows through the nozzle openings 49c into the combustion chamber 5, then it is during the subsequent combustion cycle ignited very easily. Because of the synergetic effects of the simple Ignition of the vortex movement or turbulence caused by the gas jets increases the flame propagation speed in the fuel gas mixture and results in uniform, stable combustion. The thermal efficiency of the machine will thereby increased. This increase in thermal efficiency is particularly beneficial when it is cold Machine noticeable.

When the piston 7 (FIGS. 1 and 3) moves further upwards, the pressure in the combustion chamber 5 increases rapidly. As a result, the fuel gas mixture is pressed under high pressure through the nozzle openings 49c of the cap 49 and past the valve seat 336 into the space behind and into the storage chamber. Here, the fuel gas mixture flows at high speed in the heat exchange area 43 or 43 'until the storage chamber is filled with the fuel gas mixture. As a result, the fuel gas mixture mixes even further and the atomization and evaporation of the fuel is improved in the manner described above. Shortly before the end of the compression stroke, the auxiliary valve 3Y closes and the fuel gas mixture contained in the storage chamber is retained there. At the time in FIG. 5 is shown with the arrow IC , a spark is then generated between the electrodes 27a of the spark plug 27 and the working cycle of the machine begins. Just before the piston reaches bottom dead center (BDCi) for the second time, the exhaust valve 17 is opened and the burned gas is exhausted from the combustion chamber 5 through the exhaust passage 15. It should be emphasized that the heat given off by the exhaust gas when flowing through the outlet channel 15 is transferred to the storage chamber 47 or 47 'in order to heat the fresh fuel gas temporarily stored there.

As can be seen from the above description, the fuel gas mixture under high pressure is enclosed in the storage chamber 47 or 47 'approximately at the end of the compression cycle of the machine. From there it is returned to the combustion chamber 5 approximately at the beginning of the compression stroke of the next operating cycle of the machine. As a result, a uniform turbulence can be created in the combustion chamber. In addition, ^r ith the fuel gas mixture is ignited before this turbulence is weak again. The fuel gas mixture can therefore burn off uniformly.

In the event that the cross section of the nozzle openings 49c of the cap 49 and the distance between the auxiliary valve 37 and the valve seat 336 or the cross section of the channel 43 or 43 'are smaller than in the previously explained embodiments, a time delay between the time at which the auxiliary valve 37 is opened, and the point in time at which the desired vortex movement is produced. In order to generate a vortex movement or turbulence at a desired point in time as indicated in FIG. 5 by the dash-dotted line to the left of curve S , the auxiliary valve 37 can be controlled so that it begins to open at a point in time which is earlier than the times , with which

said valve opens in the illustrated embodiments, which is shown in FIG. 5 is shown by the line S.

Finally, it should be emphasized as a further advantage of the invention that the thermal energy which was conveyed by the exhaust gases to the temporarily stored fresh gas mixture is fed back into the machine, which contributes to increasing the efficiency. If the auxiliary valve 37 is opened during the last part of the intake stroke, then the pressure energy in the temporarily stored fresh gas mixture can also be used to drive the machine. It should be emphasized that if the auxiliary valve 37 is opened as early as shown in FIG. 5 is shown with the dash-dotted line, the temporarily stored fuel gas mixture is also released into the combustion chamber at the beginning of the compression process because the cross section of the channel connecting the storage chamber 47 or 47 'to the combustion chamber 5 is not large enough. A relatively long time is therefore required to return the entire amount of intermediate storage gas iü from the storage chamber to the combustion chamber. The auxiliary valve 37 can remain open for a relatively long time during an operating cycle of the machine. The shape and manufacture of the cam which operates the auxiliary valve 37 thereby become simple. This increases the service life of this cam. Advantages of the present invention can also be seen here.

The volume of the storage chamber 47 or 47 'and the dimensions of their heat exchange area 43 or 43 'of the various embodiments of the invention ./ earth on the basis of the combustion chamber volume and the operating characteristics of the machine, for example the speed. For example favorable results are achieved if the diameter of the channel-shaped heat exchange area 43 or 43 ' was between 6 and 10 mm with a length between 80 and 100 mm and a circular cross-section.

The shape of the storage chamber is not limited to the two embodiments described, but can be changed as long as only the heat exchange between the outlet channel and her is ensured. For example, the storage chamber does not need a long bore or one long channel. It can also be part or most of the storage chamber within the Be arranged outlet channel. For example, the storage chamber 47 ', as shown in FIG. 6 shows as tube 43 " be designed with a circular cross-section, with part of the pipe wall at the same time the wall of the outlet channel 15 forms. As FIG. 7 shows, the storage chamber 47 '"be arranged concentrically in the outlet channel 15 as a tube.

The above description assumes a four-stroke carburetor engine Relation. However, the invention can also be used in a four-stroke diesel engine. Because in In the latter case, air is admitted into the combustion chamber through the inlet valve, accumulates in the Compressed air storage chamber. Also takes place here due to the warming of the cached Air in it, a pressure increase takes place, which leads to strong air jets when the auxiliary valve opens. at the diesel engine, the fuel is directed through an injector into the combustion chamber and it is no spark plug required in it.

Due to the strong eddies or turbulence that are temporarily stored in the combustion chamber by the backflowing Gases are generated, there is a considerable increase in the flame propagation speed in the combustion chamber. It is thus possible to burn fuel gases at high speed even if they have a lean air / fuel ratio or have a high proportion of recirculated exhaust gas. The thermal efficiency of the machine will thereby improved. Changes in the operating behavior of the machine caused by uneven Resulting combustion processes, avoid by the invention. Along with these advantages is a reduction in the proportion of pollutants in the exhaust gas.

For this purpose 3 sheets of drawings

Claims (3)

1 claims: 1. Internal combustion engine, consisting of a cylinder block with cylinder bore and piston, a cylinder head with recess on the underside, inlet and outlet ports with inlet and exhaust valve, a storage chamber that is exclusively used by the cylinder bore, piston and Cylinder head limited combustion chamber is connected and an elongated heat exchange area having, and an auxiliary valve between the storage chamber and the combustion chamber, the so is controlled that it opens around the beginning of the compression stroke and around the end it closes again before the ignition point t5 and until the start of the compression stroke of the subsequent working cycle remains closed, characterized in that the heat exchange area (43, 43 ') extends adjacent to the outlet channel (15) along the same 2. BifcMikraftmaschine according to claim 1, characterized characterized in that the heat exchange area (43, 43 ') has a uniform cross-section over part of its length 3. Internal combustion engine according to claim 1 or 2, characterized in that the storage chamber consists exclusively of the heat exchange area (43 ')