PL193890B1 - Internal combustion engine - Google Patents

Abstract

An internal combustion engine has throttle valves installed, each of its air intake passages connecting a surge tank with each of the cylinders. An inter-cylindrical connecting passage is formed near the air intake valves between adjacent air intake passages. An auxiliary air intake passage branches from the surge tank to bypass the throttle valve and connects to the inter-cylindrical connecting passage. An idle speed control valve is installed in the auxiliary air intake passage. Thus, stabilized combustion of the air/fuel mixture even during the low to mid-load operating ranges can be obtained to improve fuel economy and reduce NOX emissions. The invention is of particular advantage in engines using exhaust gas recirculation. <IMAGE>

Description

The present invention relates to an internal combustion engine, preferably a four-stroke multi-cylinder engine.

Internal combustion engines are known in which a mixture of air and fuel is swirled or descended in each cylinder to stabilize combustion.

However, in an engine operating in the low load range, the intake air volume is relatively low. In addition, it is not possible to swirl sufficiently inside the engine cylinders in terms of its low and medium loads.

Accordingly, in the process of stabilizing the combustion of the fuel-air mixture, and especially when using EGR (Exhaust Gas Recirculation) gases, it is very difficult to achieve a corresponding improvement in fuel economy and reduce NOX emissions.

In addition, in internal combustion engines equipped with fuel injectors for spraying fuel into the various intake channels, there are quantitative variations of the fuel injected at the respective intake channels.

The aim of the invention is to solve the above-mentioned technical problems, and in particular to obtain an internal combustion engine with a stable combustion of the fuel-air mixture in the low and medium working load range, and with better fuel economy and lower NOX emissions.

The above-mentioned technical problem has been solved by developing an internal combustion engine which uses a first inlet conduit extending from the surge tank and extending to the first cylinder, at least a second inlet conduit extending from said surge tank and extending to the second cylinder, at least one throttle in the inlet system, an inter-cylinder connecting channel that connects said inlet channels downstream of the at least one damper, an auxiliary inlet channel connecting the expansion vessel to the inter-cylinder connecting channel, and a control valve for opening and closing the auxiliary inlet channel arranged to control the flow therethrough.

Internal combustion engine, including a first intake duct extending from the surge tank and connected to the first cylinder, at least a second inlet duct extending from the surge tank and connected to a second cylinder, at least one throttle arranged in the intake system, an inter-cylinder connecting duct by which they are combined inlet channels downstream of at least one damper, an auxiliary inlet channel with which the expansion tank is connected to the inter-cylinder connecting channel, and a control valve for opening and closing the auxiliary inlet channel and regulating the flow, according to the invention, characterized in that in the auxiliary inlet channel, after the control valve, there is an auxiliary expansion tank.

The volume of the auxiliary surge tank is approximately equal to or greater than the displacement of the corresponding cylinders.

The control valve is an idle speed control valve.

The auxiliary surge tank is connected to the exhaust duct to allow exhaust gas recirculation through the auxiliary surge tank.

In the engine, the intake air stream suitably flows through the auxiliary air intake channels into the cylinders, which allows the fuel-air mixture to swirl or collapse strongly, stabilizing combustion, especially when the engine is running in the low and medium load range. Preferably, exhaust gas recirculation is used in the engine to further improve the fuel economy and further reduce NOX emissions. It is immediately apparent that the invention is particularly advantageous in application to engines with the aforesaid exhaust gas recirculation, since by increasing the amount of exhaust gas recirculation it makes it possible to increase swirl or sink in the low and medium operating load range. It should be noted that exhaust gas recirculation can be achieved not only by means of a recirculation pipe connecting the exhaust duct to the air intake duct, but also by means of a cylinder by increasing the overlapping of the opening and closing times of the engine intake and exhaust valves.

Moreover, the inter-cylinder connecting channel allows any residual fuel or air-fuel mixture remaining in the respective second cylinder or cylinders to be sucked into one cylinder during its intake stroke; This fuel acts as an auxiliary fuel, thus eliminating any quantity fluctuations in the quantity of fuel injected into individual cylinders.

PL 193 890 B1

It should also be mentioned that the invention is not limited to a two-cylinder engine, but can be applied to any multi-cylinder engine.

Inter-cylinder connecting channels may be provided between adjacent intake channels, or more, or even all, of the engine intake channels may be connected to each other.

In a preferred embodiment, the volume of the auxiliary surge tank is roughly equal to or greater than the displacement of the respective cylinders. In this way, it is possible to eliminate pumping losses in the partial load range (low and medium loads) due to the increased intake air volume from the auxiliary air inlet channel. In addition, it is also possible to reduce any pulsation of the inlet air.

Preferably, the auxiliary expansion vessel is connected to the exhaust conduit, allowing exhaust gas recirculation through said auxiliary expansion vessel. Preferably, in the low and medium operating load range, both air and recirculated exhaust gas are drawn into each cylinder from the auxiliary surge tank, further improving fuel economy and reducing NOX emissions.

In another embodiment, a variable valve timing device is installed to vary the opening and closing times of the engine intake valves, thereby increasing the amount of recirculated exhaust gas, thereby improving fuel economy and reducing NOX emissions.

Preferably, the inter-cylinder connecting channel extends into the air inlet channels, preferably adjacent to the intake valves, with the inlets of these inlet channels facing the combustion chamber of each cylinder, respectively. Thanks to this solution, an even stronger swirl or sink is created inside the cylinders, which additionally stabilizes combustion of the fuel-air mixture.

The subject matter of the invention is illustrated in the drawing in which Fig. 1 shows a first embodiment of a four-stroke, two-cylinder engine according to the invention, in vertical section; Fig. 2 is a sectional top plan view of the engine of Fig. 3; Fig. 3 is a functional diagram of the engine of Figs. 1 and 2; Fig. 4 is a diagram of the relationship between the accelerator opening and the intake air volume of the engine according to the invention; Fig. 5 is a schematic diagram of the arrangement of inter-cylinder connecting channels on a five-cylinder engine; Fig. 6 is a graph depicting the relationship between throttle opening and intake air volume in another embodiment of the four-stroke, two-cylinder engine according to the invention; 7 shows a vertical section of a second embodiment of a four-stroke, two-cylinder engine according to the invention; Fig. 8 is a sectional view of the engine of Fig. 7; Fig. 9 is a schematic operation diagram of the engine of Fig. 7; Fig. 10 is a diagram of the opening and closing times of the intake and exhaust valves of the engine of Fig. 7.

Figures 1 to 4 show an engine according to the invention in a first embodiment.

In this embodiment, a four-stroke two-cylinder engine 1 has two cylinders 3 arranged in a cylinder block with pistons moving in each cylinder 3 in a sliding motion connected by piston pins 4 and connecting rods 5 to the crankshaft 6.

A cylinder head 7 is located on top of the cylinder blocks and each cylinder has two air inlet channels 8 and two exhaust channels 9. The air inlet channels 8 and the exhaust channels 9 converge into one air inlet channel 8 and one exhaust channel 9.

Furthermore, the air inlet ports 8a and the outlet ports 9a (see Fig. 2) of the air inlet channels 8 and outlet channels 9 are open to the combustion chamber S. The inlet windows 8a and the outlet ports 9a are opened and closed for the required period of time by means of the intake valves. 11 air and exhaust valves 12, thus ensuring the required gas exchange in cylinders 3.

For clarification, the air intake valves 11 and the exhaust valves 12 are biased by valve springs 13, 14 to the normal closed position. Intake air cams 15a are integrally connected thereto on the camshaft 15 of the inlet air, and the outlet cams 16a are provided on the camshaft 16, which open the valves at the required time.

As shown in Fig. 2, gears 17 and 18 are provided at the end of the camshaft 15 of the intake air and the camshaft 16 of the exhaust air. The gears 17, 18 are engaged with an endless timing chain 19, which also engages a gear ( not shown) mounted on the crankshaft (see Fig. 1), whereby gears 17 and 18 drive the camshaft 15 of the intake air and the camshaft 16 of the exhaust gases at a speed equal to

PL 193 890 B1

1/2 of the speed of movement of the crankshaft 6, thereby opening and closing the above-described intake air valves 11 and exhaust valves 12 at appropriate times.

On the other hand, as shown in Fig. 1, there is an expansion tank 20 above the cylinder head 7, from which two air inlet channels 21 extend, which bend sideways into a U-shape. The ends of the air inlet channels 2 are connected to each cylinder in a air inlet channels 8 formed in the cylinder head 7. In horizontal sections of each of the two air intake ducts 21 there is a damper 22, the two dampers 22 are integrally connected by a camshaft 23. The dampers are opened and closed by a servo motor or other actuator 24 (FIG. 3).

In addition, an auxiliary surge tank 25 is disposed within the U-shaped side bend inside the two air inlet passages 21. An auxiliary surge tank 25 is connected to an idle control valve 27 (ISCV for short) by auxiliary air inlet passages 26 extending downstream of the reservoir. equalizer 20. An auxiliary air inlet passage 28 extends from the bottom of the auxiliary surge tank 25, the auxiliary air inlet passage 28 is bent at right angles to extend approximately horizontally towards the cylinder head 7. The volume of the auxiliary surge tank 25 is approximately equal to or slightly greater than the displacement of the cylinders.

On the other hand, as shown in Figs. 2 and 3, the engine is provided with a connecting cylinder 29 which connects two adjacent air inlet channels 8 adjacent to the suction air valve 11. In the inter-cylinder connecting channel 29 there are openings leading to air inlet channels 8 directed towards the combustion chambers of each cylinder (see Fig. 1). The secondary air intake duct 28 is also connected to the inter-cylinder connecting duct 29.

Thus, as shown in the diagram in Fig. 3, the auxiliary air inlet channels 26, 28 bypass the throttle 22 and connect to the inter-cylinder connecting channel 29. Halfway there is an auxiliary surge tank 25 and an idle control valve 27. Valve assembly the idling speed 27 and the actuator 24 is connected to an engine control unit 30 (abbreviated as ECU) and is driven by control signals from the unit 30.

As shown in Figures 1 and 2, exhaust pipes 31 are connected to each of the exhaust channels 9 formed in the cylinder head 7, each of which is connected to a catalytic converter 33, which in turn is connected to an exhaust pipe 33 going to the atmosphere. The exhaust gas temperature sensor 34 is also shown in the figures.

One of the exhaust pipes enters a pipe 35 of the exhaust gas recirculation system, which is connected to the auxiliary expansion tank 25, and between them is the valve 37 of the exhaust gas recirculation system. As shown in Fig. 3, the auxiliary surge tank 25 is also connected to a brake booster (not shown).

The method of operation of the four-stroke two-cylinder engine 1 according to the first embodiment is described below.

Fig. 4 shows the relationship between the flow rate by the volume between the idle control valve 27 and the accelerator opening angle or degree (the amount of accelerator deflection) controlling the throttle opening size α. After starting the engine 1, the throttle opening degree α is α1. Then, in the low load range, the engine control unit 30 controls that only the idle control valve 27 is open, keeping the dampers 22 fully closed.

Accordingly, in the low load ranges, the intake air sucked into the surge tank 20 bypasses the dampers 22 and flows into the auxiliary air inlet channel 26 before passing through the idle control valve 27 and then into the auxiliary surge tank 25. Simultaneously a portion of the exhaust gas produced in the previous work cycle flows through the exhaust gas recirculation pipe 35 and through the exhaust gas recirculation valve to the auxiliary surge tank 25.

Also, intake air from auxiliary surge vessel 25 and exhaust gas recirculation gases flow through auxiliary air intake duct 28 and inter-cylinder connecting duct 29 and then enter the cylinder on its intake stroke see right cylinder in Fig. 3). In this process, an appropriate amount of fuel is injected from the injectors 10 into the air inlet channels, the fuel mixed with the inlet air to form a mixture with the required air-fuel ratio.

PL 193 890 B1

In addition, the openings from the inter-cylinder connecting channel 29 to the air inlet channels 8 are directed towards the combustion chambers S in the respective cylinders, such that in the cylinder with the intake stroke there is a strong swirl, such as shown by the arrows in Fig. 3. the solution stabilizes combustion of the air-fuel mixture. As a result, it is possible to increase the amount of recirculated exhaust gas, which improves fuel economy and reduces NOX emissions. During the same intake stroke, residual fuel or fuel mixture is also drawn in the air intake duct 8 of each cylinder as an additional inter-cylinder fuel source, such intake to eliminate any variation in the amount of fuel injected from the injectors 10 into the individual cylinders. Also, a portion of the exhaust gas produced by the combustion of the air-fuel mixture in the combustion chamber S flows through the exhaust gas recirculation system pipe 35 and through the valve 37 of the exhaust gas recirculation system, and is then introduced into the auxiliary surge tank 25.

After the opening degree α exceeds the value α1 shown in Fig. 4, whereby the engine is in the range of the average loads, the engine control unit 30 drives the actuator 24 and gradually opens the throttle 22. The intake air sucked into the surge tank 20 flows into the air intake duct of the cylinder 3 during the intake stroke, after which a further part of the fuel-air mixture is sucked into cylinder 3 both from the inter-cylinder connecting channel 29 and from the air intake channel 21. Accordingly, since the inter-cylinder connecting channel 29 remains directed towards the combustion chamber S during the engine operation in the medium load range, the introduction of the air-fuel mixture into cylinder 3 causes it to swirl, which has a stabilizing effect on its combustion. This solution makes it possible to increase the use of gases from the exhaust gas recirculation system, which improves fuel economy and reduces NOX emissions.

Then, after the accelerator opening degree α has reached the value α as shown in Fig. 4, since the idle control valve 27 is closed, the motor runs at a higher load than would otherwise result from the opening degree α2. accelerator, so that, during the intake stroke, all the intake air sucked into the expansion tank 20 flows into the air intake duct 21 and into the cylinder 3, while simultaneously the air-combustion fuel mixture is fed into the cylinder 3 from both the air intake ducts 21 and 8.

Then, during high load engine operation, when large amounts of intake air flow through the air intake ducts 21, 8, the intake air flow rate is greater than it was under the low and medium load conditions, and therefore, the air-fuel mixture is fed into the air-fuel cylinders. high speed. As a result, a homogeneous air-fuel mixture is obtained inside the cylinders, which allows its stable combustion in the combustion chambers S. In the range of medium engine loads, valve 37 is completely closed, so that the exhaust gases produced by combustion of the air-fuel mixture do not flow to the auxiliary expansion tank 25. All exhaust gases pass through exhaust pipes 31, through catalytic converter 32 where they are cleaned, and then through exhaust pipe 33 which discharges them to the atmosphere.

The above describes a four-valve engine having two intake air valves and two exhaust valves per cylinder, but for engines with three intake valves and two exhaust valves as shown in Fig. 5, there must be holes in the inter-cylinder connecting duct 29 at the end of the air intake duct. facing the combustion chambers. Fig. 5 shows an exhaust duct 9, an air intake port 8a and an exhaust port 9a.

In addition, in the embodiment shown, electrically controlled throttles 22 are provided by the engine control unit 30, but in engines with accelerator-throttle cable conduits as shown in Fig. 6, the idle control valve 27 can only be opened when the engine is idling so that the inlet air bypasses the dampers 22 and flows through the auxiliary surge tank 25 and then through the auxiliary air inlet passage and inter-cylinder channels connecting to each cylinder, creating swirl or sink. Fig. 6 shows the throttle opening degree (accelerator pedal opening) on the horizontal axis.

The second embodiment is described with reference to Figs. 7 to 10. Fig. 7 shows a vertical section of a four-stroke, two-cylinder engine in this embodiment. Fig. 8 is a top plan view of the same engine. Fig. 9 is a diagram of the engine operating principle, and Fig. 10 is a diagram showing the regulation of the opening and closing of the intake valves.

PL 193 890 B1 and exhaust. In these figures, parts corresponding to those shown in Figs. 1 to 3 have been provided with the same reference numbers, and their detailed description has been omitted.

The basic structure of this embodiment of the four-stroke twin cylinder engine 1 is the same as that of the previous, first embodiment, but in this case a variable distribution device 36 is mounted at the end of the camshaft 15 that alters the timing of the opening and closing of the air intake valves 11. In this embodiment, there is also no exhaust gas recirculation pipe 35 or exhaust gas recirculation valve 37 (see Figs. 2 and 3) as in the previous first embodiment.

The principle of operation of the engine 1 of this embodiment is the same as that of the engine 1 of the previous embodiment, but in the low and medium load range, said variable displacement device 36 is driven (ON) to regulate the opening and closing of the intake valves 11 of the previous embodiment. the angular advance shown in Fig. 10 (a), thereby increasing the overlap time Δα _{1 of} the intake valve 11 and exhaust valve 12, which allows the tail gas volume in each cylinder to be increased and the internal amount of exhaust gas recirculated, thereby improving the economy fuel consumption and reduces NOX emissions while eliminating the need for an exhaust gas recirculation valve 35 as used in the first embodiment.

Then, in the high operating load range, the variable displacement device 36 is inoperative (OFF) to reduce the overlap Δα ₂ of the intake and exhaust valves 11 and 12 as shown in Fig. 10 (b).

In Fig. 10, the angle of rotation of the crankshaft is shown on the horizontal axis and the reverse crank position is indicated by TDC.

Claims (4)

An internal combustion engine, including a first inlet port extending from the surge tank and connected to the first cylinder, at least a second inlet port extending from the surge tank and connected to a second cylinder, at least one throttle arranged in the intake system, an inter-cylinder connecting port by means of the inlet channels are connected downstream of at least one damper, an auxiliary inlet channel by which the expansion tank is connected to the inter-cylinder connecting channel, and a control valve for opening and closing the auxiliary inlet channel and regulating the flow, characterized in that in the auxiliary inlet channel (26 , 28), an auxiliary expansion vessel (25) is located downstream of the regulating valve (27). 2. The engine according to claim The process of claim 1, wherein the volume of the auxiliary surge tank (25) is approximately equal to or greater than the displacement of the respective cylinders. 3. The engine according to claim The valve as claimed in claim 1, characterized in that the control valve (27) is an idle control valve. 4. The engine according to claim The apparatus of claim 1, characterized in that the auxiliary expansion vessel (25) is connected to the exhaust conduit to allow exhaust gas recirculation through the auxiliary expansion vessel (25).