This application claims priority to Germany Patent Application No. 10 2016 210 679.1, filed on Jun. 15, 2016, the contents of which are hereby incorporated by reference in its entirety.
The invention relates to an internal combustion engine.
Internal combustion engines with several cylinders can have several outlet valves for each cylinder, by means of which the exhaust gas generated in the combustion chamber, delimited by the respective cylinder, can be directed out from the combustion chamber in a synchronized manner. For this, the available outlet valves are adjustable respectively between an open position and a closed position. In the closed position, a valve body of the respective outlet valve closes a valve opening, associated therewith, and in the open position the valve body frees the valve opening for flowing through by exhaust gas.
It often proves to be a problem here that precisely during opening of the outlet valves, owing to the high gas pressure of the exhaust gas which is generated in the combustion chambers, very great forces can act on the valve bodies. These forces lead to a high mechanical stress in particular of the components which are provided for controlling the valve bodies, such as for instance an adjusting lever for adjusting the valve bodies, or a valve train for controlling said adjusting lever.
It is therefore an object of the present invention to provide an improved embodiment of an internal combustion engine, in which the above-mentioned problems are eliminated or at least only still occur in reduced form.
This problem is solved by the subject matter of the independent claims. Preferred embodiments are the subject of the dependent claims.
A fundamental idea of the invention is, accordingly, to construct a first and a second outlet valve for directing exhaust gas out from the combustion chamber of an internal combustion engine such that after the adjusting of a first valve body of the first outlet valve by a predetermined adjustment travel away from a closed position, the second valve body of the second outlet valve still closes the second valve opening.
In this way, the forces acting on the valve bodies by the exhaust gas in the combustion chamber can be reduced. This also leads to a reduction of the mechanical stress on the components which are provided for controlling the valve bodies, such as for instance the adjusting lever for adjusting the valve bodies, or the valve train for controlling the adjusting lever. As a result, the risk of damage to the internal combustion engine, in particular of the said components, is therefore considerably reduced.
An internal combustion engine according to the invention comprises at least one cylinder, in which a combustion chamber is present. Furthermore, the internal combustion engine comprises a first outlet valve and a second outlet valve for directing exhaust gas out from the combustion chamber of the cylinder. The first outlet valve comprises a first valve opening and a first valve body. The first valve body is adjustable here between a closed position, in which it closes the valve opening, and an open position, in which it frees the valve opening for flowing through by the exhaust gas. Accordingly, the second outlet valve comprises a second valve opening and a second valve body. The second valve body is adjustable between a closed position, in which it closes the second valve opening, and an open position, in which it frees the valve opening for flowing through by the exhaust gas. The internal combustion engine further comprises a shared adjusting lever, rotatable about a rotation axis, by means of which the two valve bodies are adjustable simultaneously between their respective open position and their respective closed position. According to the invention, the two valve bodies are constructed such that after the adjusting of the first valve body by a predetermined adjustment travel away from its closed position, the second valve body still closes the second valve opening.
In a preferred embodiment, the predetermined adjustment travel is between 0.1 mm and 0.5 mm. Experimental investigations have shown that in this way a particularly high load removal of the adjusting lever and therefore also of a valve train cooperating with the adjusting lever can be achieved, without this involving output losses in the internal combustion engine. In variants of this embodiment, other values are also conceivable for the predetermined adjustment travel.
For a particularly simple technical realization of the time-delayed opening of the two outlet valves, which is essential to the invention, it is proposed according to a further preferred embodiment to realize the two outlet valves such that the second valve body in the closed position of the first outlet valve projects deeper into the second valve opening than the first valve body into the first valve opening. When both valve bodies are moved out from the valve openings, the second valve body is still arranged in the second valve opening, when the first valve body is already situated outside the first valve opening, so that the principle of time-delayed opening of the two outlet valves, which is essential to the invention, is implemented.
In an alternative simple technical realization of the time-delayed opening of the two outlet valves, which is essential to the invention, it is proposed according to another preferred embodiment to arrange the second valve body in the open position of the two outlet valves at a smaller distance relative to the second valve opening than the first valve body relative to the first valve opening. Said distance can be measured here respectively along a direction perpendicular to an opening plane defined by the respective valve opening. When both valve bodies are moved away from the valve openings, the second valve body is thus still arranged at the second valve opening when the first valve body is already situated at a distance from the first valve opening, so that also the principle of time-delayed opening of the two outlet valves, which is essential to the invention, is implemented.
Particularly expediently, the distance difference of the two valve bodies in the open position corresponds substantially to the predetermined adjustment travel. This makes it possible to realize the time-delayed opening of the two outlet valves, which is essential to the invention, in a technically simple manner.
In a further preferred embodiment, the first valve body has a first body height and the second valve body has a second body height. In this variant, the second body height is greater than the first body height. This variant also makes it possible to realize the time-delayed opening of the two outlet valves, which is essential to the invention, in a technically simple manner.
In an advantageous further development, the two valve bodies have respectively substantially the geometry of a cylinder with a first or respectively a second cylinder height. In this further development, the second cylinder height is greater than the first cylinder height. This embodiment also permits the time-delayed opening of the two outlet valves, which is essential to the invention, to be realized.
Particularly preferably, the difference of the two body heights, in particular of the two cylinder heights, corresponds substantially to the amount of the predetermined adjustment travel.
In another preferred embodiment, the two valve bodies have respectively substantially identical body heights, in particular substantially identical cylinder heights. In this embodiment, the two valve bodies, in particular the two cylinders, are arranged on the adjusting lever, offset axially to one another by the predetermined adjustment travel. This variant permits the two valve bodies to be manufactured and used as identical parts.
Expediently, the rotation axis of the adjusting lever can run parallel to a rotation axis of the cam follower roller and/or to a rotation axis of the camshaft. Such an embodiment is particularly compact in construction.
Particularly preferably, the adjusting lever has a first lever arm, on which the two valve bodies are arranged. Furthermore, in this variant, the adjusting lever has a second lever arm, on which the cam follower base body is arranged.
In an advantageous further development, the internal combustion engine has a valve train for driving the adjusting lever. According to this advantageous further development, the valve train comprises a camshaft and a cam follower which is drivingly connected with the adjusting lever. Furthermore, a first cam, mounted in a torque-proof manner on the camshaft, and a second cam, arranged in a torque-proof manner and axially adjacent to the first cam, are provided. Here, the cam follower is axially adjustable between a first position, in which it is drivingly connected with the first cam, and a second position, in which it is drivingly connected with the second cam.
Particularly expediently, the cam follower can have a cam follower base body rigidly connected with the adjusting lever, and a roller, mounted rotatably on the cam follower base body. In the first position of the cam follower, this roller is drivingly connected with the first cam, and in the second position of the cam follower it is drivingly connected with the second cam. The cam follower base body is also known under term “roller pin” to the relevant specialist in the art.
Further important features and advantages of the invention will emerge from the subclaims, from the drawings and from the associated figure description with the aid of the drawings.
It shall be understood that the features mentioned above and to be explained further below are able to be used not only in the respectively indicated combination, but also in other combinations or in isolation, without departing from the scope of the present invention.
Preferred example embodiments of the invention are illustrated in the drawings and are explained further in the following description, wherein the same reference numbers refer to identical or similar or functionally identical components.
There are shown, respectively diagrammatically:
According to
Further technical details of the internal combustion engine 100, such as for example inlet valves for directing fresh or respectively charge air into the cylinder 102, and a piston arranged adjustably in the combustion chamber 103, are known to the relevant specialist in the art and are not the focus of the present invention and therefore, for reasons of clarity, are not illustrated in
As the illustration of
The two valve bodies 106a, 106b of the internal combustion engine 100 are constructed such that after the adjusting of the first valve body 106a by a predetermined adjustment travel s away from its closed position, the second valve body 106b still closes the second valve opening 105b. This characteristic of the two valve bodies 106a, 106b, which is essential to the invention, is explained below with the aid of
Through a movement of the adjusting lever 101 (the latter is likewise not shown in
In the position of the two valve bodies 106a, 106b according to
In the open position of the two outlet valves 104a, 104b, a distance d2 of the second valve body 106b to the second valve opening 105b is less than a distance d1 of the first valve body 16a to the first valve opening 105a.
The distance difference Δd=d1−d2 of the two valve bodies 106a, 106b in the open position to the respective valve opening 105a, 105b corresponds substantially to the predetermined adjustment travel s, therefore Δd=s.
As the illustration of
In an alternative variant, which is not shown in
The offset opening of the two outlet valves 104a, 104b or respectively of the two valve openings 105a, 105b, which is essential to the invention, can also be realized in a further variant with identically constructed valve bodies 106a, 106b, when the second valve body 106b in the closed position of the first outlet valve 104a projects deeper into the second valve opening 105b than the first valve body 1056a into the first valve opening 105a (not shown in the figures). With a simultaneous movement of the two valve bodies 106a, 106b, the second valve opening 105b is freed only later than the first valve opening 105a, so that also in this variant the opening of the two outlet valves 104a, 104b takes place offset to one another.
The cam follower 3 adjustable along the axial direction a between a first position, in which it is drivingly connected with the first cam 4a, and a second position, in which it is drivingly connected with the second cam 4b.
In the first position of the cam follower 3, shown in
The cam follower 3 of
The mechanical adjustment arrangement 7 further comprises a first actuator 10a, by means of which the first engagement element 8a is adjustable between a first position, shown in
The first actuator 10a is adjustable between an inactive position and an active position. For this purpose, the two actuators 10a, 10b can be constructed as linearly adjustable, electrically driven actuators. The mechanical adjustment arrangement 7 is realized in this case as an electromechanical adjustment arrangement. In other words, electrically driven actuators 10a, 10b are comprised here by the term “mechanical adjustment arrangement” 7.
The two actuators 10a, 10b are controllable by a control arrangement 11 of the valve train 1 for adjusting between their active position and their inactive position. This adjustability is realized such that the first actuator 10a in the inactive position is out of contact with the first engagement element 8a. In the course of an adjustment from its inactive position into its active position, the first actuator 10a adjusts the first engagement element 8a through mechanical contact from its second into its first position.
The adjustment of the first engagement element 8a from the first into the second position can preferably be brought about by means of the stroke movement of the cam follower 3, in particular by means of the cam follower base body 5. Here, the cam follower 3 is moved by the stroke movement brought about by the first or second cam 4a, 4b in the direction of the first actuator 10a. When the latter is in its active position, then through the stroke movement of the cam follower 3 and therefore of the first engagement element 8a, this is pressed against the first actuator 10a and is adjusted thereby into its second position.
In this state, the first engagement element 8a engages into the first slide guide 9a, so that the cam follower 3, owing to the rotary movement of the camshaft 2, is moved by means of the first slide guide 9a, arranged thereon, axially from its first into the second position. The second actuator 10b is also adjustable between an inactive position and an active position. This adjustability is realized such that the second actuator 10b in the active position is out of contact with the second engagement element 8b. In the course of an adjusting from its inactive position into its active position, the second actuator 10b adjusts the second engagement element 8b through mechanical contact from its second into its first position.
The adjustment of the second engagement element 8b from the first into the second position is preferably also brought about by means of the stroke movement of the cam follower 3, in particular by means of the cam follower base body 5. Here, the cam follower 3 is moved by the stroke movement brought about by the first or second cam 4a, 4b in the direction of the second actuator 8b. When the latter is in its active position, then through the stroke movement of the cam follower 3 and therefore of the second engagement 8b, this is pressed against the second actuator 10b and is therefore adjusted thereby into its second position.
In this state, the second engagement element 8b engages into the second slide guide 9b, so that the cam follower 3 owing to the rotary movement of the camshaft 2, by means of the second slide guide 9a arranged thereon, is moved axially from its second into the first position.
The first actuator 10a has a linearly adjustable (cf. arrow 15a) first adjustment element 12a. The latter can partially project from a first housing 16a of the first actuator 10a and be arranged linearly adjustably relative thereto. A face side 13a of the first adjustment element 12a, facing the first engagement element 8a, which can be constructed in a pin- or bolt-like manner, presses, on moving of the first engagement element 8a into the first slide guide 9a, against a face side 14a of the first engagement element 8a lying opposite the first adjustment element 12a. The second actuator 10b has a linearly adjustable (cf. arrow 15b) second adjustment element 12b. The latter can partially project from a second housing 16b of the second actuator 10b and be arranged linearly adjustably relative thereto. A face side 13b of the second adjustment element 12b, facing the second engagement element 8b, which can be constructed in a pin- or bolt-like manner, presses, on moving of the second engagement element 8b into the second slide guide 9b, against a face side 14b of the second engagement element 8b lying opposite the second adjustment element 12b.
As the illustration of
As
In the following, with the aid of the illustration of
If an adjustment of the cam follower 3 is to take place from its first into its second axial position, then the first engagement element 8a of the mechanical adjustment arrangement 7, as shown in
The first actuator 10a, as already explained, is adjustable between an inactive position shown in
The first slide guide 9a—just as the second slide guide 9b—can have a ramp structure, not shown in the figures, such that the first engagement element 8a is brought out of engagement with the first slide guide, as soon as the cam follower 3 has reached the second axial position. In this second position, the second cam 4b is in driving connection with the cam follower roller 6. The adjusting of the cam follower 3 from the second position back into the first position can take place by means of the second actuator 10b, of the second engagement element 8b and of the second slide guide 9b in an analogous manner to the transition, explained previously, from the first into the second position of the cam follower 3.
Number | Date | Country | Kind |
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102016210679.1 | Jun 2016 | DE | national |