WO2005035955A1

WO2005035955A1 - Pulse supercharging

Info

Publication number: WO2005035955A1
Application number: PCT/EP2004/011109
Authority: WO
Inventors: Reiner Wohlberg
Original assignee: Fev Motorentechnik Gmbh
Priority date: 2003-10-06
Filing date: 2004-10-05
Publication date: 2005-04-21
Also published as: DE10346830A1; DE10346830B4

Abstract

The invention relates to an internal combustion engine (1) comprising at least one intake valve (3) and an exhaust valve (4) arranged in a cylinder (2) and a pulse check valve (6) arranged in a suction pipe (5) between a collector and the intake valve (3) which is controlled in such a way that several openings of the pulse check valve (6) are carried out during the intake period of the cylinder (2). A control method for the pulse check valve (6) is also disclosed.

Description

pulse charging

The present invention relates to an internal combustion engine with at least one intake and one exhaust valve, which are assigned to a cylinder, and with at least one pulse flap, which is arranged in front of the intake valve 1. The invention further relates to a method for controlling the pulse flap.

DE 37 37 824 A1 shows the arrangement of an impulse flap in front of an inlet valve. The impulse flap, which is referred to there as an additional valve, is switched such that combustion air can freely enter a combustion chamber at the beginning of a suction phase of the cylinder. The additional valve should be controlled so that there is no backflow of combustion air entering the combustion chamber. A closing phase of the additional valve is intended to create a jam in front of the additional valve, while a suction is to occur behind the additional valve. The duration of a closing phase of the additional valve is intended to control the dynamization of the effect of suction and traffic jam.

The object of the present invention is to achieve an increase in a cylinder charge using an impulse flap.

This object is achieved with an internal combustion engine with the features of claim 1 and with a method for controlling an impulse valve with the features of claim 4. Further advantageous refinements and developments are specified in the respective dependent claims.

An internal combustion engine according to the invention with at least one intake and one exhaust valve, which are assigned to a cylinder, and at least one impulse flap, which is arranged in an intake manifold between a collector and the intake valve and has a control, has the control in such a way that this one Implemented multiple opening of the pulse flap in one suction stroke of the cylinder. This enables several short inlet mass flow pulses to be generated. This is ^~ diei-ylinderladun ^~ g ^~ increased: O ^ intake stroke of the cylinder repeatedly opened and then closed again. The pulse flap thus does not generate a single inlet mass flow pulse. Rather, it generates several mass flow pulses, which are generated separately from one another during one suction stroke of the cylinder. The generation of a plurality of inlet mass flow pulses arranged one behind the other allows a reduction in the height of the mass flow pulse compared to conventional opening methods. In this way, the flow losses generated by a triggered mass current pulse can be reduced. This allows the intake mass integral to be increased. In particular, multiple inlet mass flow pulse generation allows a minimization of flow losses compared to a comparable single inlet mass flow pulse.

Furthermore, the generation of a plurality of short inlet mass flow pulses arranged in series allows an increase in a differential pressure change applied to the pulse flap. In the case of a single mass flow pulse during an intake phase of the cylinder, the differential pressure must be limited in order not to exceed a critical pressure ratio across the pulse valve and, in particular, a supercritical pressure ratio via the pulse valve. By opening the pulse flap several times, however, the differential pressure can be controlled so that a short mass flow pulse is triggered before such a critical or supercritical pressure ratio is established. A pressure that subsequently builds up, also in the form of, for example, strong pressure vibrations, can be used again to be able to use the pressure conditions via the then closed impulse flap. In particular, the control allows the pulse flap to be opened so that subcritical flow is made possible. This limits the otherwise occurring losses via the pulse flap.

Furthermore, the multiple opening of the pulse flap during the suction phase in particular allows use in internal combustion engines in which there are strong pressure fluctuations in the intake manifold, which have hitherto not made it possible to use such means.

A further development provides that after the impulse flap is opened for the first time, it is closed again. The closing can take place completely. However, it can also be done only in part, in particular in such a way that a pressure difference can build up again via the impulse flap. Openings and closings of the pulse flap can also be controlled differently, in particular as a function of a pressure difference that lies above the pulse flap. According to a further embodiment, this pressure difference is determined directly or indirectly, a circuit of the pulse flap being derived from the pressure difference. For example, the impulse flap is opened when an applied dynamic pressure reaches a size, when a trigger is triggered. pulse mass flow achieves an increase in charge without the energy to be used for this, for example for opening the impulse flap and possible flow losses, exceeding a limit value. The limit value can be preset. However, it can also be calculated. In particular, a configuration defines a critical pressure ratio up to which the pulse flap is opened. If the pressure ratio is above this, the impulse flap is not opened. According to a further embodiment, it is provided that a bandwidth of a pressure ratio is specified, within which the pulse flap is switched.

For the rest, the term “impulse flap” is not to be understood as limiting the geometry or shape of this component. Rather, the flap can have one or more components, in particular be subdivided, at least in sections being round, angular and / or curved, over the entire length Extend cross-section or even only partially over it, have one or more materials, are in connection with one or more adjusting means, which for example may have springs and / or spring-like means, magnets, in particular electromagnets, mechanical devices and the like open centrally or on the edge, open and close or open and close like a panel.

One possibility of an arrangement as well as a design of a pulse flap is evident, for example, from DE 199 08435 A1. Further examples of arrangements, designs and also controls can be found, for example, in EP 0 141 165 A2, DE 40 30760 A1, DE 1 500 159 A1 and DE 3741 880 A1. Reference is made to these documents in the context of this disclosure with regard to the arrangement, the design and also the actuating means, wherein different features from different documents can be combined with one another.

The intake manifold in which the pulse flap is arranged can also be adapted accordingly to the internal combustion engine, its operating areas and to the control of the pulse flap. For example, in the context of this disclosure, reference is made in this regard to DE 40 31 886 A1 as well as to DE 3737828 A1.

According to one embodiment, it is provided that a map for a control device is stored, which has a shifting opening and closing of the pulse flap depending on an operating range of the internal combustion engine. One or more characteristic diagrams can be used here, and several dependencies can also be recorded here. The operating range of the internal combustion engine is detected, for example, via a rotational speed of the internal combustion engine. However, a load can also be detected. The control device is preferably integrated in an engine control. The control unit can also be present separately from the engine control and can be controlled by it. In this case, for example, the engine control system can have the corresponding characteristic map as a higher-level control unit. According to a further embodiment, it is provided that the control unit, which is separate from the engine control unit, has one or more characteristic maps stored.

A further development provides that a period of time for the opening of the pulse flap depends on the operating range of the internal combustion engine. In particular when the number of revolutions becomes lower, the duration of the opening of the impulse flap can decrease. Preferably, at a lower rotational speed, a multiple impulse flap opening is created, which has one or more openings than an operating range of the internal combustion engine with higher rotational speeds.

According to one embodiment, it is provided that the internal combustion engine is designed as a long-stroke engine. In conjunction with the multi-opening impulse flap, the impulse charging achieved thereby enables the cylinders to be filled particularly well.

Forced control of the pulse flap is preferably carried out not only during opening but also for closing. According to a further development, it is provided that the impulse flap is permanently subjected to a restoring force when it is in an open position. If an opening force is interrupted, the restoring force returns to a closed position.

In particular, according to another development, the use of the pulse flap in connection with a control enables use in internal combustion engines that have strong pressure fluctuations and / or pressure fluctuations in the intake manifold.

In addition to the pulse flap and the associated control system, the internal combustion engine preferably has a further possibility of charging the internal combustion engine. According to one embodiment, the control of the pulse flap is provided in combination with a combined supercharging. The pulse charging made possible by the pulse flap acts as a charging device in an operating range of the internal combustion engine. machine, while another charging system is active in another operating area. According to another embodiment, the control of the pulse flap is provided in the form of a hybrid charge. The pulse flap is used as an additional charging system that reinforces charging by another system. In the case of combined charging, provision is made, for example, for the pulse flap to be controlled in such a way that a resonance system in a charging system can thus be replaced.

Exhaust gas turbochargers and mechanical superchargers can be used as additional charging systems. The filling of the cylinder can also be improved by means of dynamic charging by changing the length of the intake manifold. For example, wastegate superchargers, VTG superchargers and / or VST superchargers can be used as exhaust gas turbochargers. Mechanical displacers with internal compression such as, for example, reciprocating piston loaders or screw loaders or without internal compression, such as with the Roots loader, are used as mechanical loaders. A pressure wave charger such as a Comprex charger can also be used.

The additional charging can take place, for example, in the form of a register charging and / or in the form of a two-stage regulated charging. The pulse charging by means of the switchable pulse flap can also be integrated into this.

According to a further development, it is provided that the charging system is switched via a control unit, wherein the control unit can be integrated in the engine control.

In particular, the structure of the control allows the pulse flap to be used for two, four-cylinder engines or other numbers of cylinders. Since resonance systems could only be used with three cylinders and multiples of this cylinder sequence due to the firing order, the present invention permits an expansion of combined supercharging systems to other cylinder number ratios.

The impulse flap can be used in both gasoline and diesel internal combustion engines. It can be used in stationary operation as well as in non-stationary internal combustion engines.

The impulse flap and its control can also be switched in such a way that valve overlap between the inlet and outlet valves is also supported. The pulse flap is switched, for example, in such a way that a flushing pressure gradient is used. Another embodiment provides that a pressure storage between the pulse flap and the inlet valve is generated, which can be used in particular for purging residual gas. The pulse flap is preferably switched in coordination with the openings of the inlet and outlet valves. The pulse charging by means of the pulse flap can also be carried out in coordination with the switching of an EGR valve in order to support exhaust gas recirculation.

According to a further idea of the invention, a method for controlling a pulse flap is provided, the pulse flap being arranged in front of an inlet valve of a cylinder of an internal combustion engine in an intake manifold, for increasing a cylinder charge, the pulse flap being at least in an operating range during a suction stroke of the cylinder is opened at least twice.

The method preferably provides that the pulse flap is opened and closed at least twice during the suction stroke of the cylinder. In particular, it is intended that a pulse-like intake blockage is generated in front of the pulse flap several times during a suction stroke of the cylinder. A further development provides that a multiple inlet mass flow pulse is generated, the integral of which is greater than the inlet mass flow compared to a single inlet mass flow pulse of the same duration. Another development provides that pressure storage is used in an antechamber between the impulse flap and the inlet valve. The pulse flap is preferably opened when an outlet valve assigned to the inlet valve is open. In this way, valve overlap can be supported by means of pulse charging.

Further advantageous embodiments are shown in the drawing below. However, the further developments shown there are not to be interpreted as restrictive, but the features described there can be combined in particular with the features already described above to form further configurations. Show it:

1 shows a schematic view of a cylinder with a pulse flap arranged in front of an inlet valve,

2 shows a profile of a pulse flap opening in a first operating area,

3 shows a profile of a pulse flap opening in a second operating area, 4 shows a course of an impulse flap actuation in a third operating range,

5 shows a first pressure curve between an impulse flap and an inlet valve and a second pressure curve of a cylinder pressure in an operating range corresponding to that from FIG. 3,

6 shows a mass flow curve corresponding to the pressure curve from FIG. 5 in the same operating range and

7 shows a course of a pulse flap actuation corresponding to the pressure course from FIG. 5 and the mass flow compensation from FIG. 6.

1 shows a schematic view of an internal combustion engine 1 with at least one cylinder 2, which has at least one intake valve 3 and one exhaust valve 4. A pulse flap 6 is arranged upstream of the inlet valve 3 in an intake manifold 5. The impulse flap 6 can be opened in a controlled manner and also preferably closed in a controlled manner. For this purpose, the internal combustion engine 1 has, for example, an actuating device 7. The actuating device 7 is controlled according to the illustrated embodiment of the internal combustion engine 1 via a control device 8. The control unit 8 can be integrated in an engine control unit 9. However, the control unit 8 can also be present separately from the engine control unit 9. For example, the engine control unit 9 can have one or more characteristic maps 10 stored, via which the actuating device 7 is controlled. The characteristic diagrams cover the operating areas of the internal combustion engine 1 and are in particular designed such that at least multiple opening of the pulse flap 6 is ensured during a suction stroke of the internal combustion engine 1. For this purpose, the rotational speed of the internal combustion engine 1 is determined, for example, by means of a sensor (not shown in more detail). This value is entered into the engine control unit 9, so that a state of the pulse flap 6 can be inferred from this and any further values. For example, this state can be "closing" or "opening".

According to a further embodiment, a map control takes place via the control unit 8, which has the maps required for this stored. For example, the engine control unit 9 can carry out a comparison with the control unit 8 in order to ensure a time sequence and checking. In particular, the engine control unit 9 can also be designed redundantly to the control unit 8: in the event of a failure of the control unit 8 The engine control unit 9 takes over the further operation of the impulse flap 6. Furthermore, the control unit 8 can also have further functions, for example serving as a valve control unit in the case of electro-magnetic valves or other actuated valves.

Furthermore, according to the illustrated embodiment of the internal combustion engine 1, a charging device 11 is provided in the intake manifold 5. The charging device 11 can be arranged in front of a collector in which two or suction pipes have an opening. The collector is not shown here. The charging device 1 can, however, also be arranged after a collector. The charging device 11 is preferably such that it can be operated in a coordinated manner with the pulse charging by means of the pulse flap 6.

2 shows a profile of a pulse flap opening in a first operating range of a 4-cylinder internal combustion engine. This is operated at 2000 revolutions / minute. It is shown that after passing through the top dead center of the charge exchange (LWOT) at 360 ° crank angle, the intake stroke begins, in the course of which the pulse flap is opened twice to generate mass pulses and is switched accordingly. The course of the flap opening as well as the flap closing is preferably straight as shown. However, the course can also follow a different shape, which for example has a curved course, in particular a hyperbolic course. The flap opening and the flap closing can each have a different course. There is also the possibility that a course of an opening or closing of the pulse flap has a plateau. In such a case, for example, the pulse flap is not completely opened or closed.

The opening time of the impulse flap can vary. The opening duration preferably takes place as a function of a pressure drop across the impulse flap and its dismantling after the latter has opened. Since a decrease in pressure gradient also depends in particular on the flow conditions in the cylinder, the individual opening times of the impulse flap can also have different lengths. For example, according to a first embodiment, a first opening period is shorter than a subsequent second one. According to a second embodiment, the situation is reversed. Furthermore, the distance between two opening times of the pulse flap can be shortened in such a way that this distance is less than the opening time of the pulse flap. The gradient of the opening and thus the speed of the opening as well as the closing of the impulse flap can also be different. Furthermore, the impulse flap can be closed at a time when the piston is still in the suction phase. However, the actual closing process also takes place at a point in time at which the piston reverses movement and has ended its suction phase. According to a further embodiment, the impulse flap can still be opened even if, for example, the piston has already passed bottom dead center. Further opening options and closing options also appear from the following figures.

FIG. 3 shows a course of an impulse flap opening in a second operating range of the internal combustion engine known from FIG. 2. Here, the internal combustion engine is operated at 1500 revolutions / minute. Compared to the operating point from FIG. 2, a sufficient pressure drop is achieved earlier. The distance between two openings is also larger in comparison to the distance in FIG. 2. In FIG. 2 as well as in FIGS. 3, 4 and 7, a standardized flap opening is indicated on the Y axis. This is related to a 100% open pulse flap. This makes it possible to compare different valve geometries with one another.

FIG. 4 shows another course of an impulse flap actuation in a third operating range of the internal combustion engine from FIG. 2. Here, the impulse flap experiences three opening and closing controls. The first opening takes place at a time when the piston is not yet completely at the top dead center of the charge change. A first opening of the impulse flap can therefore already be achieved at a point in time at which the suction phase has not yet begun by reversing the movement of the piston. 4 also shows that the second pulse mass flow is conducted through the pulse flap shortly after the first pulse mass flow into the cylinder. The subsequent third pulse mass flow, on the other hand, only takes place with a further, longer crankshaft offset. In particular, it can be advantageous if, for example, a first short pulse mass flow is triggered, followed by a larger pulse mass flow and then a smaller pulse mass flow.

At the operating point shown in FIG. 4, the internal combustion engine known from FIG. 2 has a rotational speed of 1000 revolutions / minute. FIG. 5 shows a first pressure curve P1 between a pulse flap and an inlet valve and a second pressure curve P2 of a cylinder pressure in an operating range of an internal combustion engine corresponding to that from FIG. 3. For a better overview, this is again given as FIG. 7. Both pressure curves P1, P2 indicate the respective influence by opening and closing the impulse flap. If the inlet valve is opened in the area of top dead center when the charge is changed, i.e. at a crank angle of 360 °, and the impulse flap is also opened shortly afterwards, a pressure build-up in front of the impulse flap is released. Therefore, the first pressure curve P1 also drops and balances itself out with the second pressure curve P2 in the cylinder. In particular, the mass flow pulse occurs in such a way that this compensation takes place within a few crank angle degrees, in particular within less than 40 ° crank angle revolution, preferably less than 30 ° crank angle revolution. Because the outlet valve is already open before the impulse flap is opened, the pressure curve P2 has an oscillation-like, slowly decreasing curve into which the first pressure curve P1 enters.

5, the first mass flow pulse enables the pressure in the cylinder to be charged. This is followed by the pressure in the intake manifold up to the impulse flap. When the impulse flap begins to close at around 405 ° crank angle rotation, the pressure peaks again, although the piston is in the suction phase due to its downward movement and the combustion chamber volume increases steadily. After the impulse flap is closed at about 420 ° crank angle rotation, the pressure drops again. The pressure drop is very steep and only breaks off when the impulse flap is opened again. This happens at about 495 ° crank angle rotation. It should be noted here that the pressure drop across the pulse flap has built up in such a way that a renewed pulse charge causes the pressure curves P1, P2 to rise again despite the further increase in the combustion chamber due to the piston moving downward. In particular, the second pulse charge has such a strength that a pressure value corresponding to the first pressure peak is thereby achieved. In this way, when the direction of movement of the piston is subsequently reversed, it is possible to start a compression stroke with a pressure which is above the ambient pressure, in particular above 1.3 bar, and preferably at least 1.5 bar.

After the inlet valve has been closed again, the pressure curve P1 also returns to its inlet pressure. FIG. 6 shows a mass flow curve corresponding to the pressure curve from FIG. 5 in the same operating range. The mass flow that flows through the intake valve into the cylinder is recorded. On the one hand, it can be clearly seen that shortly before the first opening of the pulse flap, a mass flow of current begins through the opening of the inlet valve. However, this mass flow flow decreases again, since at this point the mass between the impulse flap and the inlet valve has already largely flowed into the cylinder. This creates a negative pressure on the pulse flap, as can also be seen in FIG. 5. However, the mass flow is increased again by the first mass pulse flow due to the opening of the pulse flap. If the impulse flap is closed again, an oscillation occurs between it and the cylinder. However, this oscillation with decreasing amplitude further leads to a mass flow flowing into the cylinder.

However, opening the pulse flap a second time changes the mass flow considerably. The mass flow reaches values that are at least twice as large as those during the first mass flow pulse. In particular, mass flows of more than 0.15 kg / s can be achieved. When the valve flap is closed again, the vibrations between the valve flap and the cylinder begin again. However, this also creates mass flows that flow from the cylinder to the impulse valve. This is made possible in particular by the fact that at this point in time the piston reverses its direction of movement and the inlet valve is not yet completely closed again. If the inlet valve is closed, the mass flow oscillation also ends.

Claims

claims

1. Internal combustion engine (1) with at least one inlet (3) and one outlet valve (4), which are assigned to a cylinder (2), as well as an impulse flap (6), which is located in an intake manifold (5) between a collector and the inlet valve (3) is arranged and has a control which has a multiple opening of the pulse flap (3) in a suction stroke of the cylinder (2).

2. Internal combustion engine (1) according to claim 1, characterized in that a map for a control unit (8) is stored, which has a shifting depending on an operating range of the internal combustion engine (1) opening and closing of the pulse flap (6).

3. Internal combustion engine (1) according to claim 1 or 2, characterized in that a time duration of the opening of the pulse flap (6) depends on the operating range of the internal combustion engine (1).

4. Method for controlling a pulse flap (6), which is arranged in front of an inlet valve (3) of a cylinder (2) of an internal combustion engine (1) in an intake manifold (5), for increasing a cylinder charge, during a suction stroke of the cylinder (2) the pulse flap (6) is opened at least twice in at least one operating area.

5. The method according to claim 4, characterized in that the pulse flap (6) is opened and closed at least twice during the suction stroke of the cylinder (2).

6. The method according to claim 4 or 5, characterized in that several times during a suction stroke of the cylinder (2) an impulse-like intake jam is generated in front of the impulse flap (6).

7. The method according to claim 4, 5 or 6, characterized in that a multiple inlet mass flow pulse is generated, the integral of which is greater than the inlet mass flow compared to a single inlet mass flow pulse of the same duration.

8. The method according to any one of claims 4 to 7, characterized in that a pressure storage in an antechamber between the impulse flap (6) and the inlet valve (3) is used.

9. The method according to any one of claims 4 to 8, characterized in that the pulse flap (6) is opened when an outlet valve (4) assigned to the inlet valve (3) is open.