CN114961976A

CN114961976A - External source ignition type internal combustion engine

Info

Publication number: CN114961976A
Application number: CN202210166485.6A
Authority: CN
Inventors: C·诺尔迈尔; G·费德霍费尔
Original assignee: AVL List GmbH
Current assignee: AVL List GmbH
Priority date: 2021-02-24
Filing date: 2022-02-23
Publication date: 2022-08-30
Also published as: DE102022104221A1

Abstract

The invention relates to an external ignition internal combustion engine (1) comprising a cylinder head (2), at least one cylinder (3) having a combustion chamber (4), wherein a prechamber (5) which opens into the combustion chamber (4) and has at least one ignition device (6) and at least one intake duct (7) are arranged in the cylinder head (2) for each cylinder, wherein a connecting duct (8) is provided together with a control device (9) arranged in the connecting duct (8), wherein the connecting duct connects the intake duct (7) in flow communication with the prechamber (5).

Description

External source ignition type internal combustion engine

Technical Field

The invention relates to an external ignition internal combustion engine, comprising a cylinder head, at least one cylinder with a combustion chamber, wherein for each cylinder a prechamber with at least one ignition device and an intake channel leading into the combustion chamber are arranged in the cylinder head.

Background

Internal combustion engines with precombustors are known from the prior art.

Combustion methods using precombustors are used in particular in lean-running, spark-ignited, external-source internal combustion engines. The advantage of starting the combustion in the prechamber, rather than in the main combustion chamber, is that even with high air ratios, a small ignition energy is sufficient to ensure efficient and also pollutant-free combustion of the entire cylinder charge. The prechamber is in fluid communication with the main combustion chamber via one or more overflow passages formed by orifices. The fuel-air mixture flows into the main combustion chamber via one or more intake valves and is then moved into the prechamber during compression, thereby providing an ignitable mixture within the prechamber.

For the ignition of the fuel-air mixture, spark ignition systems and also oil-injection ignition methods are used. In the case of spark ignition, fuel or a fuel-air mixture is additionally fed into the prechamber a number of times in order to have a mixture which is significantly richer in fuel and therefore also more ignitable than the main combustion chamber at the start of combustion. For this purpose, an injector is always arranged in the prechamber.

A disadvantage of the known solution is that in this case a lot of construction space is required and the processing costs are correspondingly high.

Disclosure of Invention

The present invention addresses this. The aim of the invention is to improve the ignitability in the precombustion chamber and to save structural space.

According to the invention, this object is achieved in that, in an internal combustion engine of the type mentioned in the introduction, a communication channel is provided together with a control device arranged in the communication channel, wherein the communication channel connects the intake channel in flow communication with the prechamber.

The advantages thereby obtained are in particular that residual gases can be removed from the prechamber by the design of the internal combustion engine according to the invention, whereby an ignitable mixture can be provided therein and the ignitability thereof can be improved. A part of the air fed from the intake port into the combustion chamber is fed into the precombustor through the communication passage, thereby purging it with air and scavenging the remaining gas located therein. The opening and closing of the communication channel is adjustable and/or controllable by means of a control device in order to control and/or also completely inhibit the flow from the inlet channel to the prechamber. According to the invention, a connection between the intake channel and the prechamber, in particular for conducting a substance, is provided by means of a connecting channel. Thus forming a purged prechamber. The communication channel is designed and arranged in particular here such that there is a pressure difference between them.

The external ignition internal combustion engine according to the invention is designed in particular as an aspirated engine or a supercharged engine.

In this case, it can be provided that the prechamber is formed by a prechamber sleeve, wherein advantageously a sleeve can be provided, which sleeve comprises the ignition device. The prechamber sleeve and the sleeve are in particular each formed in one piece and/or connected to each other. Hereby it is possible to simply remove the prechamber part from the cylinder head when ignition is a problem, which makes maintenance and replacement easier and cheaper. When the prechamber sleeve and the sleeve are connected to each other, this can be achieved, for example, by a threaded connection with a seal. It can therefore be provided that the sleeve is designed in one piece and the prechamber sleeve is designed in one piece, which are then connected to one another. However, it is also possible for the sleeve and prechamber sleeve to be formed jointly in one piece.

It is particularly advantageous that the prechamber is free of injection means. No injection means such as, in particular, injectors are therefore provided in the prechamber itself. This makes it possible to save costs and space, which in turn improves the cooling of the cylinder head, in particular, because of the low floor space requirement. In internal combustion engines with prechambers known from the prior art, an injector is always provided in the prechamber, which injector must be cooled in particular or which is designed as a passive prechamber.

Advantageously, the control device is designed as a valve, in particular as a check valve or throttle valve. Advantageously, the control device can also be designed as a controllable flow-rate regulating valve. The direction and/or amount of flow between the intake duct and the prechamber can be controlled by means of the valve. It is particularly preferred that the control device inhibits back-streaming from the prechamber to the intake tract. The control device may preferably cover the entire length of the communication channel or be arranged only in a part thereof. An injector may preferably be provided in the intake tract, whereby a defined amount of fuel can be fed into the prechamber together with air by means of the control device.

The control device is advantageously designed as a non-return valve having a valve body with two passage openings, wherein the medium can flow through the non-return valve from the first passage opening toward the second passage opening. The non-return valve further comprises a spring element and a closing means with a valve disc element, wherein the closing means is connected to the spring element at a first end and the valve disc element is arranged at a second end of the closing means, wherein the valve disc element opens the second through-flow opening above a defined pressure, wherein a communication channel is provided together with a control means arranged in the communication channel, wherein the communication channel connects the inlet channel in flow communication with the prechamber.

This has the advantage, inter alia, that the diaphragm reduces the minimum pressure at which the valve disc allows the medium to flow through the non-return valve. While also preventing reverse flow.

The check valve in principle allows a medium flow in one direction only, wherein the medium flows into the check valve via the first through-flow opening and, when the valve disc is in the open position, flows out of the check valve via the second through-flow opening. The valve disk, in particular a part of the closure device, is either formed integrally with the closure device or is connected thereto in a positionally fixed manner. The partition is also fastened in particular to the closure device, wherein the closure device has a thickening downstream of the partition. The closing means is elongated upstream of the valve disc and has a constant diameter outside the thickened region. In the region of the thickening, the closure has a larger diameter, so that the diaphragm rests against the thickening. If the pressure applied to the diaphragm is great enough, it will move, thereby transmitting the diaphragm pressure to the valve disc. That is, the valve disk opens in particular together with the diaphragm when the medium pressure exerted on the diaphragm is sufficiently high. The medium pressure required for the movement of the partition and thus of the entire closure device in the medium flow direction is predefined.

If no medium flows through the non-return valve or if the medium pressure is too low to open the closure device, the closure device can be moved back into the closed position by means of a spring element, which is arranged in particular in a positionally fixed manner on the closure device.

The closure device opens from a defined pressure which the medium has when it contacts its elements (valve disk or diaphragm). The closure device can also open the flow opening when a defined pressure difference is exceeded, wherein a pressure difference in the scope of the invention means a defined increase in the medium pressure exerted on the closure device. This can also be changed for example from 0 to a specific value if initially no medium flows or surges, after which the medium enters the non-return valve via the first flow through hole.

The valve disk is arranged in particular downstream of the second through-opening and is opened by the medium pressure in the flow direction away from the second through-opening.

The separating wall is in particular of plate-like design, i.e. it essentially has a cylindrical shape, wherein the separating wall diameter is in particular many times greater than its height. The valve disk is designed as a disk, wherein the diameter of the valve disk is also in this case in particular greater than its maximum height. The height of the valve disk is not constant due to its geometry, wherein the valve disk has a maximum height at the point of connection to the remainder of the closure device.

The valve body is designed with a bore in its interior for the medium to flow through, wherein a constriction is formed, in particular in the region of the second flow opening, which is in contact with the valve disk when no pressure is exerted on the valve disk. The constriction is formed in particular by an increased valve body material and forms a valve seat for the diaphragm.

The check valve is designed for the passage of gaseous or liquid media or mixtures thereof. For example, the medium can be a mixture of liquid fuel and air.

Advantageously, the diaphragm in the closed position prevents the medium from flowing through the check valve and allows the medium to flow through when a defined pressure difference is exceeded, wherein the pressure difference for opening the diaphragm is smaller than the pressure difference for opening the valve disk. It is thus ensured that the closure device opens even in the event of small pressure changes, so that the non-return valve is opened for flow in the desired and only direction.

Advantageously, the diameter of the diaphragm is greater than the diameter of the valve disc member. This means that the diaphragm extends further radially outward within the check valve than the disc member. Thus ensuring that the diaphragm moves in the flow direction even when the pressure is low.

It is also advantageous if the valve disk at least substantially bears against a valve seat of the valve body in the closed position. This causes the entire check valve to close and no media can flow through it. The valve seat also ensures that the check valve is always closed in the other direction. In particular, the valve disk may not be completely or tightly seated with respect to the valve seat. The valve disk is therefore preferably placed against the valve seat in such a way that the valve disk cannot in particular be inserted but still closes the second flow opening. Alternatively, the valve disk member can be inserted with a slight gap. In principle, however, the disk element can also bear completely against the valve seat.

Advantageously, the diaphragm in the closed position at least substantially bears against a further valve seat of the valve body. The other valve seat has correspondingly the same advantages as the valve seat of the valve disk and cooperates therewith to prevent the closure element from being able to move against the flow direction. As far as the abutment against the other valve seat is concerned, it is worth noting that the diaphragm does not abut completely or tightly, and therefore does not provide a double fit. The partition is therefore preferably substantially in contact with the valve seat, so that it cannot be inserted in particular but nevertheless closes the second flow opening. Alternatively, the partition plate may be inserted with a small gap.

Preferably, a chamber is formed between the valve disc member and the diaphragm. When the closure is in the open position, the medium flows through or past the chamber towards the second flow opening. A longitudinal portion of the closure device is generally centered through the chamber.

The check valve is in particular at least largely made of wear-resistant steel. It is also preferably capable of being manufactured using a 3D printing method.

Particularly preferably, a non-return valve is provided with a valve body with two flow openings, wherein the non-return valve can be traversed by a medium from a first flow opening in the direction of a second flow opening, with a spring element and with a closure device with a valve disk element, wherein a first end of the closure device is connected to the spring element and the valve disk element is arranged at a second end of the closure device, wherein the valve disk element opens the second flow opening when a defined pressure is exceeded, wherein a communication channel is provided together with a control device arranged in the communication channel, wherein the communication channel connects the intake channel in flow communication with the prechamber. The check valve is preferably designed as described above.

The check valve is preferably used in a cylinder head of an internal combustion engine, in particular in a connecting channel through which a fuel-air mixture flows.

Advantageously, the inlet duct has two partial inlet ducts with a duct partition between the partial inlet ducts, wherein the communication duct opens into the prechamber in the duct partition. Here, the communication passage preferably branches into the prechamber upstream of the division into the intake ports. The branch intake duct opens into the combustion chamber and introduces air therein. Preferably, the intake port is divided in the flow direction into two partial intake ports which open into the combustion chamber in order to introduce air and/or a fuel-air mixture into the combustion chamber. An internal combustion engine having such a cylinder head can be manufactured simply. In particular, such a cylinder head is manufactured by casting.

In principle, it may also be advantageous if the inlet duct is divided into two partial ducts, which then open into the combustion chamber, and the connecting duct opens out from one of the partial ducts into the prechamber. It can also be provided that a connecting channel extends from each of the two partial gas ducts, said connecting channels merging into a connecting channel upstream of the prechamber and opening into the prechamber. It may also be appropriate that one connecting channel each leads from two branch air ducts to the prechamber, whereby two communicating channels are provided between the inlet duct and the prechamber.

If the internal combustion engine comprises more than one cylinder and therefore also more than one prechamber, each prechamber is provided with its own communication channel. It may each branch off itself from the respective intake duct or a common connecting duct may be provided first, which also branches off into individual connecting ducts towards the respective prechambers.

It is expedient if at least one first injection device is arranged for each cylinder in the intake tract, wherein the first injection device is designed in particular as a multipoint injector. No injector is therefore provided in the prechamber itself, but rather a multipoint injector (MPI injector) is used for fuel injection, which injector is in particular already provided in the intake manifold. By the purging of the prechamber thus formed, which can be supplied with fuel or a fuel-air mixture, a higher mixture ignition capability is achieved, in particular in regions in which the prechamber generally does not have as good an effect as in catalytic heating, partial engine load operation and/or engine start operation, for example. In the internal combustion engine of the present invention, unlike the passive prechamber, fuel is fed to the prechamber indirectly through the control means provided in the communication passage. Via the communication channel, air or a fuel-air mixture can be fed into the prechamber, depending on the operating point of the internal combustion engine. The prechamber thus designed is therefore purged with air or a fuel-air mixture.

The first injection device is particularly preferably arranged such that its fuel flow is arranged in such a way that it opens into the passage of the prechamber towards the communication channel. The ignition capability of the mixture is thereby further improved, since there is always sufficient fuel and/or fuel-air mixture, which in particular also advances sufficiently quickly to the ignition device in the prechamber. The flow direction of the fuel flow is thus directed toward the prechamber, in particular toward the passage opening of the communication channel into the prechamber, due to the provision of the injection device which generates the fuel flow. The fuel flow thus reaches the ignition device with as little flow resistance as possible.

In the internal combustion engine according to the invention, the installation space is optimized and space-saving since the prechamber itself has no injection device, and optimum ignition is ensured by simultaneously supplying the fuel-air mixture via the communication channel.

It is advantageous to provide a second injection device for direct injection into the combustion chamber, which is designed in particular as a DI injector. It may be advantageous to provide only the second injection device for direct injection into the combustion chamber. That is, then, no injector is provided in the precombustion chamber, and no injector is provided in the intake passage. It is advantageous to provide an own second injection device for each cylinder. However, it may also be advantageous to provide each cylinder not only with an MPI injector, but also with a DI injector, in order to ensure an optimum ignition capability not only during cold starts of the internal combustion engine, but also during normal operation thereof.

Advantageously, a preheating device is provided, which is designed in particular preferably as an electrocautery pin. The preheating device is arranged upstream of the control device, in particular in the communication channel, and is preferably used for heating the fuel and/or air and/or the fuel-air mixture during a cold start of the internal combustion engine. During normal operation of the internal combustion engine, the preheating device is generally not used. The glow pin-shaped preheating device is arranged in particular in a bore in the cylinder head and projects into the connecting channel. Possibly, a recess is also produced for accommodating the preheating device during casting of the cylinder head. By this preheating arrangement, a sufficiently high temperature level can be obtained in the prechamber, so that a stable combustion in the prechamber can be achieved.

It is also advantageous to provide an additional ignition device in the combustion chamber. That is, in addition to the ignition device in the prechamber, one ignition device is also provided in the combustion chamber, and therefore at least two ignition devices are provided. The additional ignition device opens in particular into the combustion chamber and improves the cold start behavior of the internal combustion engine.

In the internal combustion engine according to the invention, it is advantageous if the prechamber and the communication channel are designed in one piece with the cylinder head. That is, preferably no additional parts are required, thereby reducing costs. The communication channel is preferably simply co-cast during casting of the cylinder head, wherein it can also be subsequently drilled into it.

Drawings

Further features, advantages and effects arise from the embodiments shown below. The figures referenced at this time show:

FIG. 1 illustrates a partial cross-sectional view of an internal combustion engine of the present invention;

FIG. 2 shows a schematic diagram of an internal combustion engine;

fig. 3 shows a sectional view of a control device designed as a non-return valve.

Detailed Description

Fig. 1 shows a longitudinal section of a part of an internal combustion engine 1 according to the invention. Fig. 1 shows a single-cylinder internal combustion engine or cylinder 3 with a cylinder head 2 arranged above it. However, the internal combustion engine 1 according to the invention may preferably also have more than one cylinder 3, for example 3 or 4 or more cylinders 3. Fig. 2 thus shows an example of a 4-cylinder internal combustion engine 1. The part shown in fig. 1 will then be multiplied according to the number of cylinders. The internal combustion engine has a cylinder head 2 and a cylinder block 13, wherein a cylinder 4 is arranged in the cylinder block 13. Other details are not shown or visible in fig. 2 for simplicity.

The internal combustion engine 1 of the present invention includes a cylinder head 2 and a cylinder 3, wherein a combustion chamber 4 is provided in the cylinder 3. A prechamber 5 is also provided, which adjoins substantially vertically to the combustion chamber 4 and opens into it. The prechamber 5 comprises ignition means 6 for igniting a combustible mixture, in particular consisting of fuel and air.

Also provided in the cylinder head 2 are an intake passage 7 for intake air and a water jacket 13 for cooling the cylinder head 2.

The inlet channel 7 is in flow connection with the prechamber 5 via a communication channel 8, so that air can flow from the inlet channel 7 into the prechamber 5. In order to control the flow between the inlet channel 7 and the prechamber, a valve-like control device 9 is arranged in the communication channel 8. The control device 9 is preferably designed as a non-return valve to avoid a back flow from the prechamber 5 to the inlet channel 7.

The inlet channel 7 is divided downstream of the connecting channel 8 into two partial gas channels, which open into the combustion chamber 4. The communication passage 8 thus branches off from the intake passage 7 into the branch intake passage upstream of the division. In order to provide an optimum packing arrangement, the communication channel 8 opens into the prechamber in a channel dividing wall of the two partial gas channels.

An injection device 10 in the form of a multi-point injector is also arranged in the intake tract, through which fuel enters the intake tract 7 and from there as a fuel-air mixture into the combustion chamber 4, wherein a further ignition device is arranged in the combustion chamber.

Via the communication channel 8, the fuel-air mixture also enters the prechamber 5, where it is ignited by the ignition device 6. In order to provide an ignitable mixture in the prechamber 5, an injection device 10 is therefore used which is present in the intake tract 7.

In order to bring the substance in the communicating channel 8 to a given temperature, a preheating device 12 is provided, which is preferably designed as an electrothermal glow pin.

Fig. 3 shows a sectional view of the control device 9 designed as a non-return valve. The check valve includes a valve body 21 having flow holes 31 and 41 formed in the ends thereof. Via said through

openings

31, 41, a gaseous and/or liquid medium can flow through the non-return valve from the first through opening 31 towards the second through opening 41. The non-return valve further comprises a spring element 51 and a closing means 61 with a valve disc element 71. The closing means 61 is connected at a first end to the spring member 51 such that a valve disc member 71 arranged at a second end of the closing means 61 can be brought into a closed position. Closure device 61 further includes a diaphragm 81 disposed upstream of valve disc member 71 and downstream of spring member 51.

The check valve is designed to allow the medium to flow in only one direction. For this purpose, a valve seat 91 is provided in the region of the second flow opening 41, wherein the valve disk 71 abuts against the valve seat 91 downstream of the latter in the position closing the non-return valve. Likewise, the diaphragm 81 abuts against the other valve seat 110 in the closed position. This design of the check valve prevents the media from flowing backwards. The two

valve seats

91, 110 are formed by the material accumulation of the valve body 21.

The valve disk 71 is part of the closure device 61 and is of essentially elongate design, wherein the valve disk 71 is arranged at the second end. The partition 81 is arranged substantially centrally on the closure 61. Between the valve disk 71 and the partition 81, a chamber 111 is formed, through which the medium flows when the closing means 61 is open to flow.

If a medium with sufficient pressure is applied to the diaphragm 81, the diaphragm is pushed in the flow direction and also opens the valve disc 71 and thus the entire closing means 61: the medium can now flow through the non-return valve. If the pressure drops again or below a defined value, the closure device 61 is moved back into the closed position again by the spring element 51.

Claims

1. An external ignition internal combustion engine (1) comprising a cylinder head (2), at least one cylinder (3) having a combustion chamber (4), wherein a prechamber (5) opening into the combustion chamber (4) and having at least one ignition device (6) and at least one intake duct (7) are arranged in the cylinder head (2) for each cylinder (3),

it is characterized in that a communication channel (8) is provided together with a control device (9) arranged in the communication channel (8), wherein the communication channel connects the air inlet channel (7) and the prechamber (5) in a flow-through manner.

2. An internal combustion engine (1) according to claim 1, characterized in that the prechamber (5) is without injection means.

3. An internal combustion engine (1) as in claim 1 or 2, characterized in that the control device (9) is designed such that the valves are check valves or throttle valves.

4. An internal combustion engine (1) according to claim 3, characterized in that the control device (9) is designed in the form of a non-return valve having a valve body (21) with two through-openings (31; 41), wherein the non-return valve can be flowed through by a medium from the first through-opening (31) towards the second through-opening (41), a spring element (51) and a closure device (61) with a valve disc element (71), wherein a first end of the closure device (61) is connected to the spring element (51), wherein the valve disc element (71) is arranged at a second end of the closure device (61), wherein the valve disc element (71) opens the second through-opening (41) as a result of a defined pressure, wherein the closure device (61) comprises a diaphragm (81), wherein the diaphragm (81) is arranged upstream of the valve disc element (71).

5. Internal combustion engine (1) according to claim 4, characterized in that the diaphragm (81) blocks the medium passage through the non-return valve in the closed position and opens the medium passage from a defined pressure difference, wherein the pressure difference for opening the diaphragm (81) is smaller than the pressure difference for opening the valve disk (71).

6. An internal combustion engine (1) as in claim 4 or 5, characterized in that the diameter of the partition (81) is larger than the diameter of the valve disc member (71).

7. Internal combustion engine (1) according to one of claims 4 to 6, characterized in that in the closed position the valve disk member (71) at least substantially abuts against the valve seat (91) of the valve body (21).

8. Internal combustion engine (1) according to one of claims 4 to 7, characterized in that in the closed position the partition (81) at least approximately abuts against a further valve seat (110) of the valve body (21).

9. An internal combustion engine (1) as in any one of claims 4 to 8, characterized in that a chamber (111) is formed between the valve disc member (71) and the partition (81).

10. Internal combustion engine (1) according to one of claims 1 to 9, characterized in that the inlet duct (7) has two branch ducts with a duct partition between them, wherein the communication duct (8) opens into the prechamber (5) in the duct partition.

11. Internal combustion engine (1) according to one of the claims 1 to 10, characterized in that at least one first injection device (10) is arranged for each cylinder (3) in the intake tract (7), wherein the first injection device (10) is designed as a multipoint injector.

12. Internal combustion engine (1) according to one of claims 1 to 11, characterized in that at least one second injection device (11) is provided for direct injection into the combustion chamber (4).

13. Internal combustion engine according to one of claims 1 to 12, characterized in that a preheating device (12) is provided.

14. An internal combustion engine according to any one of claims 1 to 13, characterized in that at least one additional ignition device is provided in the combustion chamber (4).