DE1816237A1 - Device for reducing the hydrocarbon content of engine exhaust gases while a motor vehicle is decelerating - Google Patents

Description

PATENT LAWYERS 1818237 Dr. D. Thomsen H. Tiedtke G. Bühling

Dipl.-Chem. Dipl.-Ing. Dipl.-Chem.

8000 MONKS 2

VAL 33

TELEPHONE 0811/22 68 94

TELEGRAM ADDRESS: THOPATENT

Munich 2o. December 1968 case PG23-683 / T 2937

Nissan Motor Company, Limited Yokohama City / Japan

Apparatus for reducing the hydrocarbon content of engine exhaust gases during deceleration

of a motor vehicle

The invention relates to a system for reducing the hydrocarbon content of exhaust gases from a gasoline-powered vehicle Automotive engine, and more particularly to a system for controlling the air-fuel ratio one via the slow-running Qemischzuström or -zuflußweg a carburetor sucked into the engine air-fuel mixture when decelerating the vehicle.

The presence of hydrocarbons in the machine

4 3/1056

Gasing is of particular interest to the automotive industry for two main reasons: air pollution and Fuel economy. Numerous attempts have been made to solve the problems associated with these two factors been; Among other things, attempts have been made to improve the performance characteristics of the carburetor in such a way that the air-fuel ratio of the air-fuel mixture is controlled during operation of the vehicle. It turned out however, the prior methods and systems encountered difficulties, widely varying among those Driving Conditions · the air-fuel ratio of the engine fuel invariably at a suitable level without impairing the drivability of the vehicle keep.

Motor vehicle operation is usually divided into four different driving states: idling, acceleration, normal cruising speed and delay. The ranges of hydrocarbon contents in engine exhaust vary noticeably according to the type of vehicle operationj Investigations that were carried out on different, different vehicle operations Engine exhausts made showed that the hydrocarbon content of exhaust gases had the highest values

909843/1056

reached during the delay. This results in part from the inability of the gasifier to supply the engine with an air-fuel mixture containing a proper for satisfactory combustion of the mixture air-fuel ratio has, and partly due to the unsatisfactory * the combustion as well as from misfiring Air-fuel mixture in the combustion chamber, which is caused by the considerable increase in the negative pressure in the intake manifold during the deceleration. In order to achieve satisfactory combustion of the air-fuel mixture during deceleration, it is therefore important to enable the carburetor to supply the engine with a mixture of an air-fuel ratio that is best suited to avoid the presence of partially burned or unburned · Eliminate the air-fuel mixture in the engine exhaust ™ and also increase the amount of mixture to be supplied to the engine, thereby preventing the intake manifold from rising excessively during deceleration. The fact is, however, that the air-fuel ratio of the mixture in the carburetor remains essentially unchanged when the vehicle is decelerated, despite changes in the engine speed and the negative pressure in the intake pipe, with changes in the vehicle speed from that which is determined when the vehicle is idling. This is why

909843/1056

it is necessary for reducing the hydrocarbon content of engine exhaust during deceleration for either an air-fuel ratio for idle operation of the air-fuel mixture that is on a for the achievement of satisfactory combustion of the mixture is reduced or a device is installed, which the air-fuel ratio below a can control predetermined height.

It is therefore the object of the invention to create a system with which the hydrocarbon content of engine exhaust gases that during deceleration of a motor vehicle is reduced, in part, by reducing the air-fuel ratio of the engine fuel mixture as a function of the fluctuation of the at the beginning of the deceleration of the motor vehicle steeply increasing intake line negative pressure is maintained at a suitable level and in part by keeping the suction line negative pressure in such a Degree is reduced, resulting in a minimal output of hydrocarbon content leads, so that the air pollution which would otherwise be prevented by the presence of unburned air-fuel mixture or hydrocarbons would be caused in the engine exhaust and at the same time a considerable saving in engine fuel consumption

90984371056

is achieved.

The following are preferred embodiments below Described with reference to the accompanying drawings, which are given as an example and in which correspond to one another Parts are provided with the same reference numbers in all figures:

Fig. 1 is a graph showing a desirable example of the relationship between the air · Fuel ratio in an air-fuel mixture and the vehicle speed during the delay shows;

Fig.2 is a graph showing the relationship air-fuel ratio determined between the urfcer idle conditions of the engine and the hydrocarbon content of the engine exhaust at idle, acceleration, and normal Driving, i.e. under the operating modes with the exception of the deceleration, j

Fig.3 is a graph showing the effect of the negative pressure in the intake manifold indicates the hydrocarbon content in the exhaust gas;

009843/1056

- JiT -

Fig. 4 is a partial vertical section through a

Carburetor with a device according to the invention and

Fig. 5 is a view similar to FIG

Modification of the device according to FIG. H ™ shows.

A carburetor of conventional design has the characteristics that it despite changes in the engine speed and the negative pressure in the intake pipe when the vehicle speed changes during deceleration with an air-fuel ratio works, which is specifically intended for idling operation, so that the fuel mixture of the engine at an optimal Air-fuel ratio is lacking which satisfies ensuring combustion of the mixture during the delay.

The hydrocarbon content of engine exhaust gases generated during deceleration would be minimized when the air-fuel ratio of the mixture is in is controlled to correspond to curve (a) of Fig. 1, which is a desirable example of the relationship the vehicle speed and the air-fuel ratio. A simple and economical auxiliary

909843/1056

medium for the approximate realization of the curve (a) in a conventional carburettor can consist in the air-fuel ratio determined to be within a certain range to Restrict ^s> example, anywhere from 12 to 13 in consideration of the air-fuel ratio during idling of common motor vehicles . This can be achieved by adjusting the air-fuel ratio using the standard idle fuel adjustment screw; as previously stated, the idle air-fuel ratio also remains essentially unchanged during deceleration. Such a restriction of the air-fuel ratio within a relatively small range, however, leads to an increased hydrocarbon content during idling, acceleration and normal driving, as can be seen from "curve (b) in FIG. 2, so that it is advantageous over the whole different vehicle modes of operation except for the deceleration to keep the air-fuel ratio at a higher level by preferably using a carburetor that is operable with a lean air-fuel ratio. Therefore, it is necessary to adjust the air-fuel ratio for the deceleration (during the a particularly large amount of hydrocarbons is contained in the engine exhaust gases) regardless of

909843/1056

the other modes of operation to control the total amount
to reduce the hydrocarbon content of engine exhaust gases, which are generated under all driving styles in motor vehicle operation.

However, it is extremely difficult in the low speed mixture inflow path of conventional carburetors, in consideration of
the performance characteristics of the carburetor keep the air-fuel ratio of the fuel mixture at an optimal level during deceleration without a suitable one
Control device, although the air-fuel ratio can be adjusted as desired during idling. In addition, problems in controlling the air-fuel ratio for idle operation arise from the difficulty of avoiding individual errors, which generally range from 9 to 15 des
Air-fuel ratio are usually below
Rule of thumb is set.

Another important factor in reducing the hydrocarbon content of engine exhaust is influence the high intake manifold vacuum that suddenly arises at the initial stage of deceleration. As soon as the motor vehicle begins to slow down, the suction

909843/1056

line vacuum sharply, ie to more than 650 mm Hg, while it remains on the order of 500 mm Hg during idle operation. This results exclusively from the fact that the throttle valve of the carburetor remains essentially completely closed during the deceleration and shuts off the flow of the air-fuel mixture in the main mixture inflow or inflow path despite engine operation at a relatively high speed, which is proportional to the running speed of the vehicle. The intake manifold negative pressure, which has increased to such a level, inevitably leads to unsatisfactory combustion of the air-fuel mixture in the combustion chamber of the engine and misfires, so that the hydrocarbon content of the engine exhaust gases emitted during deceleration increases markedly.

This itend of the hydrocarbon content can be clearly seen from curve (c) of Fig. 3, which is a typical example of the relationship between the hydrocarbon content in the machine exhaust gas and the negative pressure in the machine suction line indicates. As shown, the hydrocarbon content becomes below regardless of the intake manifold vacuum held at a noticeably low level during about 53o mm Hg it increases very steeply at higher negative pressures.

109843/1056

In order to reduce the hydrocarbon content of engine exhaust gases even more effectively, it would be advantageous during the delay to increase the fuel mixture amount, which results in a reduction in the suction line vacuum. It would be the best way to reduce hydrocarbon levels in the engine exhaust during deceleration, the amount of engine fuel mixture in to such an extent that the manifold vacuum is decreased to about 53o mm Hg. By the braking effect however, the reduction of the suction line negative pressure to such an extent is detrimental to the engine on the driving ability of the motor vehicle, so that this is unsuitable for practical purposes. It should therefore be the Intake line negative pressure can be reduced to a value at which the driving ability of the motor vehicle in no way is affected. With that in mind, the reasonable amount to which the intake manifold vacuum would be reduced would be should, generally in the vicinity of 600 mm Hg. As shown in curve (c) of FIG. 3, the decrease is of the suction line negative pressure to approximately 600 mm Hg, obviously for the minimization of the hydrocarbon content conducive to engine exhaust.

If you have the. accumulated amount of hydrocarbon in engine exhaust produced during idling, acceleration and

109843/1056

M. - 4 * -

normal driving (namely, under all motor vehicle driving styles with the exception of deceleration) wants to reduce a minimum, it would be advantageous, as can be seen from curve (b) of FIG. 2, a carburetor of those To use a design that can be operated with a relatively lean air-fuel mixture, i.e. with a mixture which has a relatively high air-fuel ratio. The carburettor of this type would have the flow parameters dictated by the lean side of the flow band in the generated carburetor flow curve. Will the system according to the invention in a carburetor with these If flow characteristics were applied, this would be for reducing the hydrocarbon content of engine exhaust gases conducive to being used during the various modes of operation of the Motor vehicle are ejected.

One embodiment of the invention for accomplishing this Objective is shown in Fig. 4, in which the carburetor in State of the delay mode is shown with the throttle valve essentially fully closed. The throttle Io can be of the type commonly used in conventional carburetors and rotatable on a shaft 11 sits.

Through the opening 12, which is above the slow-speed emul-

909843/1056

Yaw air chamber 13 is arranged and vented to the atmosphere is, air is fed into the low-speed mixture inflow path. In the normal state, air introduced from the opening 12 is also admitted to the first and second slow emulsifying air inlets IM and 15, respectively. The amount of air to be introduced through the opening 12 can be determined in a suitable manner by varying the inside diameter of this opening. Air passing through the first emulsifying air inlet 14 is fed to the low-speed nozzle 16, where it is in a predetermined mixing ratio with the liquid fuel mixed from a liquid fuel source (not shown) is fed in via the fuel inflow channel 17. The mixture of air and fuel is dosed at the low-speed nozzle 16, and atomized and for further mixing with air introduced through the second emulsifying air inlet 15 the slow speed saving nozzle 18 supplied. The resulting engine-fuel mixture is now guided through the fuel mixture inflow channel 19 and injected into the main mixture inflow path of the carburetor through the slow speed outlet 2o and the idle outlet 21 downstream of the throttle plate Io. The one to be injected through the idle outlet 21 The amount of fuel mixture can be adjusted in the usual way by using the idle adjustment screw 3o.

According to the invention, the slow-speed emulsifying air chamber 909843/1056

18J6237 Ji - ■ »-

arranged so that it communicates with the main mixture inflow path of the carburetor below the idle outlet 21, namely by means of an outlet 22, a line 23, an opening 24, a valve arrangement 25 and a delay outlet 29.

As previously stated, the suction line remains negative pressure during idle operation of the order of 500 mm Hg, so that the ball valve element 27 through the action of the coil spring 28 against the valve seat 26 is pressed, whereby the flow of air through the valve arrangement 25 into the delay outlet 29 is prevented.

Soba, on the other hand, the vehicle with the slowdown starts, the suction line negative pressure rises steeply, e.g. to more than 650 mm, so that the ball valve element 27 in Direction of the delay outlet 29 is pulled away from the valve seat 26, so that air through the valve arrangement 25 can flow into the main mixture inflow path below the throttle valve Io.

Thus, the introduced through the opening 12 of the chamber 13 can Air during the deceleration to both the main mixture inflow path as well as to the low-speed mixture inflow

90Ö843 / 1056

get away while the Motor vehicle can only flow into the low-speed fuel flow path. The through the valve arrangement 25 The amount of air flowing out can be determined by a suitable choice of the inside diameter of the opening 24, preferably for about 600 mm Hg in order to come into agreement with the characteristics of curve (c) of FIG. The public

tion 12 is dimensioned in the inner diameter that the Inside of the emulsifying air chamber 13 during idle operation at a normal or slightly lower pressure and during the delay is kept at a suitable vacuum level.

With this design of the low-speed fuel inflow path, the engine is fed during idle operation with an amount of fuel mixture that is considered reasonable with conventional carburetors. During the deceleration, however, a considerable amount of air is fed into the main mixture inflow path via line 23, so that the pressure in chamber 13 becomes negative. This leads to the fact that the to the first and second emulsifying air inlets Ik and 15

the amount of air allowed is reduced proportionally to the pressure drop in the chamber 13, so that the fuel to be sprayed out through the slow-speed outlet 2o and the idle outlet 21

909843/1056

mixture is enriched. Air is added to the fuel mixture exiting through these two outlets 2o and 21, which flows through the opening gap between the throttle valve Io and the outlet 2o, as well as air which is introduced from the delay outlet 29, so that the amount and the Air-fuel ratio of the mas chin fuel mixture assumes optimal values for the deceleration of the motor vehicle

As is apparent from the above description, in this embodiment of the invention with the one from the first and second emulsifying inlet 14 and 15, respectively Fuel mixture to be mixed amount of air controlled by reducing the pressure level in the chamber 13, which is decreased during the delay. However, for the increased simplification of the mechanical structure of the carburetor more beneficial, only the amount of air to be admitted into the second emulsifying air inlet by the arrangement of a slow-speed emulsifying air chamber at the second emulsifying air inlet to control, whereby a similar performance and effect is obtained as in the first embodiment of the invention is achieved. ·

Such a concept in the carburettor structure is advantageous 909843/1056

realized in the air-fuel ratio control system of Fig. 5, the constituent parts thereof according to the first embodiment corresponding components are provided with the same reference numerals.

According to Fig. 5 are in the low-speed mixture inflow path a low speed emulsifying air chamber 13 'and a second Emulsifying air inlet 15 is provided so that air fed in from the atmosphere through the opening 12 'with the fuel mixture is mixed through the slow speed nozzle 16 is to be performed and that during idle operation the slow speed outlet 2o indthe idle outlet 21 in the Main mixture inflow path sprays, while when delayed this Air through line 23 also to the delay exit is sucked.

In contrast to the first embodiment, for increased stability of the air shut-off valve performance, the through air sucked through the outlet 22 by the cooperation of a solenoid valve assembly 3o and a membrane switch unit 34 controlled, which are electrically wired together. the Design of the membrane switch unit 34 is such that it through a membrane 35 in two different chambers 36 and

909843/1056

37 is divided, of which the suction chamber 37 communicates via the line 42 with the suction line or the suction line system (not shown) and of which the atmosphere chamber 36 has inside a set of movable and stationary contacts 39 and ko , of which the movable contact .39 is connected to the membrane 35 by a rod 41. The membrane 35 is normally urged towards the chamber 36 under the action of the spring 38, so that the movable contact 39 is kept free from the stationary contact 40.

The solenoid valve assembly, on the other hand, has im Inside a needle valve element 32, which under the action of the coil spring 31 normally against the valve seat or stop 33 is depressed so that air introduced through line 23 at a flow through to the delay exit 29 is prevented as long as the solenoid valve assembly 3o remains idle.

Now starts at normal cruising speed Slowing down the running vehicle increases particularly in the initial stage of decelerating the motor vehicle the intake manifold vacuum instantly increases to a level of 650 mm Hg or more, as previously discussed.

90984 3/1056

It follows that the membrane 35 is drawn in the direction of the suction side, ie to the right in the drawing, so that the movable contact 39 comes to rest against the stationary contact ko. The solenoid valve arrangement, which is now electrically connected to the membrane switching unit, is used, so that the valve element 32 is pulled away from the valve seat 33 against the action of the helical spring 31. This means that the air introduced from the chamber 13 'through the outlet 22, the line 23 and the opening 24 can pass the passage leading to the delay outlet 29 and enter the main mixture inflow path of the carburetor 'Air is allowed through the line 23 to the main mixture inflow path, the pressure in the chamber 13' drops considerably, whereby the fuel mixture discharged through the Langsaralauf and the idle outlet 21 is correspondingly enriched.

If the diameters of the opening 12 ', the first emulsifying air inlet I ² J and the second emulsifying air inlet 15 are selected in a suitable manner during the development of the carburetor, the air-fuel ratio of the engine fuel mixture can be set to optimal values for idling operation and deceleration operation. Furthermore, through

909843/1056

Correct determination of the dimensions of the opening 2k lead to the amount of air to be sucked in from the chamber 13 'to the delay outlet 29 to a desired level of the suction line negative pressure.

From the above description it follows that During the deceleration of the motor vehicle, the hydrocarbon content of engine exhaust gases can thereby be reduced can be done by introducing air from the low speed emulsifying air chamber the intake line negative pressure in the main mixture inflow path of the carburetor below the throttle valve and that the engine main fuel mixture enriched by reducing the amount of air that the. Fuel mixture in the low speed mixture inflow path is to be mixed.

According to a feature of the invention, the hydrocarbon content of engine exhaust by effectively utilizing the steep rise in intake manifold uriter pressure in the low speed mixed inflow path reduced without major dimensional changes of the carburetor in its entirety are. This is particularly important for the invention in that that the concentration of hydrocarbons in engine exhaust gases by improving the quality of combustion in the

90 9 843/105 6

• Combustion chamber especially during the deceleration of the Motor vehicle is sufficiently stabilized.

According to a further feature of the invention, not only the amount, but also the air-fuel ratio ^ of the engine fuel mixture during deceleration of the motor vehicle can be controlled independently of other modes of operation of the vehicle in such a way that the engine-fuel mixture richer during deceleration and richer during idling, acceleration and normal Travel operation of the motor vehicle is kept leaner.

According to a further feature of the invention, the suction line negative pressure, which is in the initial stage the deceleration of the motor vehicle is steeply increased, decreased, ™ for example to about 6op mm Hg, which is the height for the mini · malization of the hydrocarbon content in the engine exhaust gases without impairing the driving ability of the motor vehicle is considered appropriate, as previously stated with reference to curve (c) of FIG. 3.

If the device according to the invention continues a carburetor is used which operates on the lean side of the flow range of the carburetor flow curve, so leads this by itself to the reduction of the hydrocarbon

909843/1056

content of engine exhaust gases in every mode of operation of the Motor vehicle.

Since the system according to the invention has a relatively lean Air-fuel mixture is operable, it proves to be advantageous both for reducing the carbon monoxide content of engine exhaust as well as savings in engine fuel consumption.

Despite the presentation and explanation of two forms of performance of the invention it will be apparent to those skilled in the art that this has been done for illustrative purposes only and that numerous Modifications can be made without departing from the inventive idea and the scope of the invention as defined in the appended claims.

309843/1056

Claims (3)

Claims , Carburetor for a gasoline-powered vehicle -L machine machine with a Hauptgemsichzuströmweg, which leads to the Ein ™ suction line of the machine and is kept essentially closed during the idle and deceleration operation of the motor vehicle by a throttle valve housed therein, and with a slow mixture inflow path, via which the machine during this operation with a Air-fuel mixture can be fed with a predetermined air-fuel ratio and which has a first and a second emulsifying air inlet which are open to the atmosphere, a channel for liquid fuel connected to a fuel source and to the first and α second emulsifying air inlet, a mixture channel for the passage of the Mixture of the air from the first and second emulsifying air inlet and the fuel from the fuel passage, a slow-speed outlet which is connected to the mixture passage and at one point in the main mixture inflow path. opens, at which the throttle valve closes this path during the idle mode and the deceleration mode, and an idle outlet that communicates with the slow-speed outlet and downstream of the throttle in the 9098A3 / 1056 Main mixture inflow path opens, characterized by a system for reducing the air-fuel ratio that during the deceleration operation of the motor vehicle through the slow-speed mixture inflow path into the Combustion chamber of the engine to be sucked in air-fuel mixture, this system having an air chamber, which is vented to the atmosphere through an air port and which has the first and second emulsifying air inlets communicates, a valve arrangement which communicates with the suction line of the machine and consists of a valve element, a coil spring and a valve seat, furthermore an air chamber via a suction opening with the valve assembly connecting suction line wherein the Valve element under the action of the coil spring normally is pressed against the valve seat in order to pass the suction line through the valve element during idling operation keep closed and being increased when developing negative pressure in the suction line of the machine during of the delay operation, the valve element as a function of the increase in the negative pressure in the intake line and against the action of the coil spring from the valve seat comes free, whereby air from the air chamber into the suction line of the through the suction line and the valve arrangement Machine and at the same time the amount of air that is in $ 09843/1056 the air-fuel mixture is to be received, which in turn is to be introduced into the main mixture inflow path through the slow-speed outlet and the idle outlet. 2. System according to claim 1, characterized in that the valve arrangement further comprises a solenoid device, which is energized in. Dependent on the increase of the negative pressure in the suction line of the machine, in order to lift off of the valve element from the valve seat. 3. System according to claim 2, characterized in that the solenoid means through an electrical circuit an energy source is connected to a membrane switch unit, which is divided into two different chambers by a membrane is divided, of which the atmosphere chamber has a set of moving and stationary contacts inside, both of which are connected to the electrical circuit and of which the suction chamber with the suction line of the Machine is connected. And has a coil spring inside, through which the moving contact is normally from the stationary contact is kept away, with the occurrence of an increased negative pressure in the suction line of the machine the membrane under during the deceleration operation 909843/1056 the effect of the negative pressure acting on this and against the effect of the last-mentioned helical spring in one direction for contacting the movable contact with the stationary contact is displaced so that the solenoid means is energized by the energy source during deceleration operation. 9Ö98A3 / 1056 U blank page