EP1044319B1 - Internal combustion engine - Google Patents

Abstract

The invention relates to an internal combustion engine comprising at least one combustion chamber (5) which has at least two valves (4) that can be hydraulically or pneumatically actuated and are each guided in a valve guide (3). Said valves are namely an inlet valve for admitting fuel or an air-fuel mixture into the combustion chamber (5) before the combustion process, and an exhaust valve for permitting the burned gases to exit the combustion chamber (5) after the combustion process. In order to reduce the reaction times of the valve control in internal combustion engines of this type, the invention provides that the valves (4) can be respectively fixed with regard to the valve guide (3) by an electrically actuatable fixing element.

Description

The present invention relates to an internal combustion engine with at least one combustion chamber that has at least two each guided in a valve guide and hydraulically or has pneumatically actuated valves, namely a Intake valve for the admission of fuel or one Air-fuel mixture in the combustion chamber before Combustion process and an exhaust valve to exhaust the Combustion gases from the combustion chamber after Combustion process.

The present invention also relates to a Valve arrangement comprising a valve guide and a hydraulic or pneumatic. actuatable and in the Valve guide guided valve.

State of the art

Such internal combustion engines with hydraulic or pneumatically operated valves are from the state of the Technology known. You have compared to internal combustion engines with camshaft operated valves the advantage that the Valves can be controlled independently of each other can. Due to the variable valve control, the Noise reduction and the consumption and that Exhaust behavior of internal combustion engines significantly improved become.

It turns out in these known internal combustion engines however as a disadvantage that the hydraulic or pneumatically controlled valves for quite a long time Show response times. So it takes about 300-400 ms until an open valve on one corresponding command from a control unit responds Opening movement ended and in a desired one Valve position comes to a standstill. With the help of a such control of the valves, for example Stroke of the valves can be varied: Due to the Long response times can trigger the valves only with limited accuracy and an inclusion of hydraulic or pneumatic Valve control in a regulation is also very consuming.

An internal combustion engine is known from DE 37 39 775 A1 hydraulically or pneumatically operated valves of the known type. The valves are each assigned an electrically actuated fastening element, through which the valve is relative to the valve guide can be set. Such an internal combustion engine with hydraulically or pneumatically operated valves can can also be found in DE 42 09 590 Cl.

The valves of the known from the two publications Internal combustion engines can only be in predetermined Positions, namely in the open and the closed Valve position.

The present invention is therefore the object based on creating a way that valves from Internal combustion engines in any position relative to the Valve guides can be set.

To achieve this object, the invention is based on of the internal combustion engine of the type mentioned at the beginning, that the valves are each electrically actuatable clamping element relative to the valve guide can be determined.

Advantages of the invention

By using the electrically operated clamping elements the valves can be in any valve position relative to the valve guide. The Response times of these electrically operated clamping elements are very short. With their help, the response times of the hydraulically or pneumatically controlled valves can be significantly shortened by simultaneously with the Hydraulic or pneumatic arrangement also faster responsive electrically operated clamping elements can be controlled. The activation of the clamping elements, for example. during the opening of a valve causes a brief Block hydraulic or pneumatic Valve actuation assembly. The quickly responsive Clamping elements that hold the valve relative to the valve guide set, then act against the hydraulic or Pneumatic arrangement that tries as long as that Continue opening the valve until it opens the control signal to end the opening movement responds. However, the blocking has no consequences on the hydraulic or pneumatic valve actuation arrangement, because the valve actuation means (a liquid or a Gas) are compressible and thus have a resilient effect.

According to the invention, it has been recognized that the long Response times of the hydraulic or pneumatic controlled valves due to the high volume flows occur within the valve actuation assembly. By the use of additional electrically operated Clamping elements with significantly shorter response times can the response times of the valves of the invention Internal combustion engine can be shortened significantly.

A clamping element can relative to the valve Clamp the valve guide using a friction lock. Thereby there is no abrupt or sudden termination a valve opening movement after reaching one desired valve opening position. Rather, it will Valve during the opening movement relative to the Valve guide braked. A valve can also pass through the use of the clamping element in any Opening position can be determined.

According to an advantageous development of the invention suggested that the valve stem have a stroke stop has, when opening the valve on the clamping element hits, and that the clamping element in a relaxed state by the stroke stop in a clamping element guide relative to the valve guide against the force of a spring element is axially displaceable. The clamping element provides one variable stroke stop, through which the valve stroke variable can be adjusted. The clamping element can in relaxed state shifted within the valve guide become. Moving the clamping element in the direction smaller valve lifts are carried out by means of a spring element, that acts between the valve guide and the clamping element. Moving the clamping element in the direction of larger strokes the valve stem takes place during the Opening movement of the valve. Is the one you want When the valve position is reached, the clamping element is activated and the valve in its current position relative to that Valve guide fixed.

According to another advantageous development of the Internal combustion engine according to the invention is proposed that the valve stem has a stroke stop that at Opening the valve meets the clamping element, and that the clamping element in the relaxed state in the Clamping element guide relative to the valve guide the force of a spring element hydraulically or pneumatically is axially displaceable. Also in this embodiment the clamping element enables a variable stroke setting. The clamping element can be in a relaxed state within the Valve guide to be moved. Moving the Clamping element in the direction of smaller valve strokes by means of a spring element which is between the valve guide and the clamping element acts. Moving the Clamping element in the direction of larger strokes is carried out by means of a hydraulic or pneumatic adjustment arrangement. By means of the adjustment arrangement, the clamping element regardless of a valve opening movement in a any valve stroke limitation position can be brought. is the desired valve lift position is reached Clamping element activated and relative to the valve guide established. The valve can now only be opened so far until the stroke stop hits the clamping element.

Several exemplary embodiments have been described above, at which the clamping element in the relaxed state relative to the valve guide is movable and in activated State is determined relative to the valve guide. It is but also conceivable that the clamping element in a relaxed State determined relative to the valve guide and in activated state is displaceable.

Preferably in internal combustion engines with at least two inlet valves and / or at least two Exhaust valves per combustion chamber, the clamping elements from in each case at least two of the inlet valves and / or the Exhaust valves with one another via a bridge element connected. In this way, multi-valve internal combustion engines each the clamping elements of the inlet or the exhaust valves of a combustion chamber via the Valve arrangement can be controlled together. The clamping element advantageously has at least one piezoelectric actuator for actuating the clamping element on. Piezoelectric actuators have the advantage that they have particularly short response times and within about 20 ms after a corresponding control signal Clamping the clamping element relative to the valve guide cause. That means the response times of the valves the internal combustion engine according to the invention approximately by the factor Can be shortened by 10 - 20.

According to an advantageous development of the invention the clamping element is designed as a clamping ring, the has a circumferential gap in which the at least a piezoelectric actuator is arranged such that an excitation of the piezoelectric actuator to one Enlargement of the circumference of the clamping ring and to one Setting the clamping ring in the clamping element guide leads. In the relaxed state of the piezoelectric actuators the clamping ring has an outer diameter that is smaller than is the inside diameter of the valve guide; the clamping ring is axially displaceable within the valve guide. in the excited state of the piezoelectric actuators, stretch these out and widen the gap in the clamping ring, whereby whose outer diameter is enlarged until the Outer surface of the clamping ring on the inner surface of the Valve guide is present. Through the continued force of the excited piezoelectric actuator becomes the clamping ring by means of frictional engagement relative to the valve guide established.

But it is also conceivable that at least one piezoelectric actuator in this way in the gap of the clamping ring to arrange that the clamping ring in the relaxed state of piezoelectric actuators with its outer circumference on the Inner circumference of the valve guide rests and by means of Friction on an axial movement within the Valve guidance is prevented. In this case, a Excitation of the piezoelectric actuators to one Reduce the circumference of the clamping ring, causing the Clamping ring could be moved axially.

According to another advantageous development of the The present invention proposes that Clamping element is designed as a clamping ring circumferentially has a gap in which two to each other spaced jaws are arranged such that a Increase the distance between the jaws to one Enlargement of the circumference of the clamping ring and to one Setting the clamping ring in the clamping element guide leads, being in the distance between the jaws of the at least one piezoelectric actuator arranged in this way is that excitation of the piezoelectric actuator too an increase in the distance between the jaws leads. In the relaxed state of the piezoelectric actuators the clamping ring has an outer diameter that is smaller than the inside diameter of the valve guide; the The clamping ring is axial within the valve guide displaceable. In the excited state of the piezoelectric Actuators, these expand and widen the distance between the jaws. The pressed apart Clamping jaws widen the gap in the clamping ring, thereby whose outer diameter is enlarged until the Outer surface of the clamping ring on the inner surface of the Valve guide is present. Through the continued force of the excited piezoelectric actuator becomes the clamping ring by means of frictional engagement relative to the valve guide established. It is conceivable to have several on one clamping ring Column. At least in part of the column in such a case, piezoelectric actuators or Clamping jaws can be arranged with piezoelectric actuators.

The jaws can on the clamping ring in the gap be attached. In this embodiment, the Jaws and the piezoelectric actuators within the Clamping element guide in the axial direction together with the Clamping ring.

Alternatively, according to a particularly advantageous Further development of the invention proposed that the Clamping jaws relative to the clamping element guide in the axial Direction are set. This has the advantage that the Jaws and the piezoelectric actuators are not within the clamping element guide in the axial direction move together with the clamping ring.

According to a preferred development of the invention Internal combustion engine is proposed that Clamping element is designed as a clamping ring on the at least one relative to the clamping element guide in axially fixed jaw acts, each by means of the at least one piezoelectric actuator is so radially inward that it can be moved from acts on the outside of the clamping ring. There are two basic ones Embodiments of this training conceivable.

In the first embodiment, the clamping ring has one Outside diameter that is smaller than the inside diameter the valve guide. The clamping ring is in a relaxed state of the piezoelectric actuators within the Clamping element guide axially displaceable. When excited of the piezoelectric actuators, the jaws become radial shifted inward until the inner surfaces of the jaws rest on the outer surface of the clamping ring. Through the continues to be effective force of the piezoelectric actuators the clamping ring through the clamping jaws by means of friction an axial movement within the clamping element guide prevented. The clamping ring is in the clamping element guide set relative to the valve guide. From static For reasons it makes sense that the clamping ring at this Embodiment does not have a circumferential gap.

In the second embodiment, the clamping ring is in the relaxed state of the piezoelectric actuators inside the clamping element guide is not axially displaceable because it has an outer diameter that is larger than that Inner diameter of the clamping element guide. The outside surface the clamping ring lies on the inner surface of the Clamping element guide and the clamping ring is by means of Friction on the clamping element guide fixed. in the excited state of the piezoelectric actuators Jaws moved radially inwards until the Inner surfaces of the jaws on the outer surface of the Place the clamping ring on. Through the continued force the jaws of the piezoelectric actuators act in this way on the clamping ring so that its outer circumference is reduced. The clamping ring expediently has a circumferential one Gap, the width of which is due to the force of the jaws is reduced. The clamping ring now has an outer diameter, which is smaller than the inside diameter of the Clamping element guide, and is within the Clamping element guide axially displaceable. To the clamping ring in a desired valve end stroke position relative to the Determine the clamping element guide, the piezoelectric actuators relaxed again.

As a further solution to the problem of the present Invention is based on the valve arrangement of the initially suggested that the valve by means of an electrically actuated clamping element relative can be determined for the valve guide.

The valve is advantageously used as an inlet valve Intake of fuel or a fuel-air mixture into a combustion chamber of an internal combustion engine or as Exhaust valve for exhausting combustion gases from the Combustion chamber trained. Especially when used as Intake or exhaust valve of an internal combustion engine come the particular advantages of the valves according to the invention for Wear.

drawings

Figur 1a

eine erfindungsgemäße Brennkraftmaschine im Ausschnitt mit einem Befestigungselement gemäß einer ersten Ausführungsform in Frontansicht, teilweise im Schnitt;

Figur 1b

das Befestigungselement aus Figur 1a in Draufsicht, im Schnitt entlang der Linie A-A;

Figur 2a

ein Befestigungselement gemäß einer zweiten Ausführungsform in Frontansicht;

Figur 2b

das Befestigungselement aus Figur 2a in Seitenansicht, teilweise im Schnitt;

Figur 2c

das Befestigungselement aus den Figuren 2a, 2b in Draufsicht im Schnitt entlang der Linie B-B;

Figur 3a

ein Befestigungselement gemäß einer dritten Ausführungsform in Frontsicht, teilweise im Schnitt;

Figur 3b

das Befestigungselement aus Figur 3a in Draufsicht, im Schnitt entlang der Linie C-C;

Figur 4a

ein Brückenelement zum Verbinden der Klemmelement zweier Ventile in Frontansicht; und

Figur 4b

das Brückenelement aus Figur 4a in Seitenansicht.

Three preferred exemplary embodiments of the present invention are explained in more detail below with reference to the drawing. Show it:

Figure 1a

an internal combustion engine according to the invention in a detail with a fastener according to a first embodiment in front view, partially in section;

Figure 1b

1a in top view, in section along the line AA;

Figure 2a

a fastener according to a second embodiment in front view;

Figure 2b

the fastener of Figure 2a in side view, partially in section;

Figure 2c

the fastening element from Figures 2a, 2b in plan view in section along the line BB;

Figure 3a

a fastener according to a third embodiment in front view, partially in section;

Figure 3b

3a in top view, in section along the line CC;

Figure 4a

a bridge element for connecting the clamping element of two valves in front view; and

Figure 4b

the bridge element of Figure 4a in side view.

Description of the embodiments

FIG. 1a shows an internal combustion engine 1 according to the invention shown in the detail. In a cylinder head 2 the Internal combustion engine 1 is designed as a valve guide 3, in which a valve 4 is guided. The valve 4 closes or opens access to a combustion chamber 5 of the Internal combustion engine 1. A is used to close the access Valve plate 6 of valve 4 by means of a valve spring 7 pressed against a valve seat 8, which is at the access to the Combustion chamber 5 is formed. The valve 4 will by means of a hydraulic or pneumatic Valve actuation arrangement 21 actuated.

A valve stem 9 of the valve 4 is in the valve guide 3 axially displaceable. The valve stem 9 has one Stroke stop 10 on. The valve 4 is as an intake valve for the admission of fuel or a fuel-air mixture in the combustion chamber 5 before Combustion process trained. The valve 4 could, however also as an exhaust valve to exhaust the Combustion gases from the combustion chamber 5 after Combustion process can be formed without a Change in the structure of the valve 4 would result.

Within a clamping element guide 20 is a Clamping element, in particular as a clamping ring 11 Fastener arranged. The clamping ring 11 has circumferentially a gap 12 in which a piezoelectric actuator 13 is arranged such that a Excitation of the piezoelectric actuator 13 to one Enlargement of the width of the gap 12 and thus to one Increasing the circumference of the clamping ring 11 leads.

The clamping ring 11 is in the relaxed piezoelectric Actuator 13 axially within the clamping element guide 20 displaceable. The stroke stop 10 of the valve stem 9 hits with a valve opening movement on the clamping ring 11. By axially moving the clamping ring 11 within the Clamping element guide 20 can therefore be the valve lift of the valve 4 can be set. The clamping ring 11 can be relaxed State of the piezoelectric actuator 13 in the direction of a larger valve strokes against the force of a spring element 14 by means of a hydraulic adjustment arrangement 15 axially displaced within the clamping element guide 20 become. By controlling the hydraulic adjustment arrangement 15 can the desired valve stroke end position by means of Clamping rings 11 can be set. In the desired one The valve stroke end position then becomes the piezoelectric actuator 13 activated and the clamping ring 11 in the Clamping element guide 20 relative to valve guide 3 established.

The following figures are for the same Components matching reference numerals used.

In Figure 1b, the clamping ring 11 from Figure 1a is a plan view shown in section along the line A-A.

In Figure 2a, the fastener is according to a second Embodiment shown. The fastener according to the second embodiment also has a clamping ring 11 with a circumferentially arranged gap 12.

In the gap 12 are two spaced apart Clamping jaws 16 arranged such that an enlargement the distance 17 between the jaws 16 to one Increasing the circumference of the clamping ring 11 leads. By doing Distance 17 between the jaws 16 are two piezoelectric actuators 13 arranged such that a Excitation of the piezoelectric actuators 13 to one Increasing the distance 17 between the jaws 16 leads. Thus, by activating the piezoelectric actuators 13 the circumference of the clamping ring 11 enlarged and this in the clamping element guide 20 relatively to be fixed to the valve guide 3. The jaws 16 are relative to the clamping element guide 20 in the Cylinder head 2 set in the axial direction. To the Setting a desired valve stroke end position is the Clamping ring 11 by means of the hydraulic adjustment arrangement 15 or by means of the spring element 14 relative to the Jaws 16 axially within the valve guide 3 postponed. After reaching the desired one The piezoelectric actuators become the valve stroke end position 13 activated and the clamping ring 11 is in the Clamping element guide 20 relative to valve guide 3 established.

In Figure 2b, the fastener of Figure 2a is in Side view shown. Figure 2c shows that Fastening element from Figures 2a and 2b in plan view on average along the line B-B.

In Figure 3a is a fastener according to a third Embodiment shown. The fastener has also one in a relaxed state within the Clamping element guide 20 axially slidably mounted Clamping ring 11 on. In the inner circumference of the clamping element guide 20 is a jaw 18 formed by a piezoelectric actuator 13 such radially inwards can be moved from the outside onto the clamping ring 11 acts and against him within the clamping element guide 20 axial displacement secures. This one too Embodiment is the setting of a desired one Valve stroke end position by axially shifting the Clamping ring 11 by means of the hydraulic adjustment arrangement. 15 against the force of the spring element 14.

FIG. 3b shows the fastening element according to FIG. 3a in Top view shown in section along the line C-C.

In internal combustion engines 1 with at least two Intake valves and / or at least two exhaust valves can the clamping elements 11 of several of each Inlet valves or the exhaust valves over a Bridge element 19 are connected together.

Such a bridge element is shown in FIGS. 4a and 4b 19 shown by which the clamping elements 11 two Valves 4 are interconnected.

Claims (11)

1. Internal combustion engine, with at least one combustion space (5) which has at least two hydraulically or pneumatically actuable valves (4) guided in each case in a valve guide (3), to be precise an inlet valve for the inlet of fuel or of a fuel/air mixture into the combustion space (5) prior to the combustion operation and outlet valve for the outlet of the combustion exhaust gases from the combustion space (5) after the combustion operation, characterized in that the valves (4) can be fixed in relation to the valve guide (3) in each case by means of an electrically actuable clamping element.
2. Internal combustion engine according to Claim 1, characterized in that the valve stem (9) has a stroke stop (10) which impinges onto the clamping element during the opening of the valve (4), and in that, in the detensioned state, the clamping element can be displaced axially in a clamping-element guide (20) in relation to the valve guide (3) counter to the force of a spring element (14) by means of the stroke stop (10).
3. Internal combustion engine according to Claim 1, characterized in that the valve stem (9) has a stroke stop (10) which impinges onto the clamping element during the opening of the valve (4), and in that, in the detensioned state, the clamping element can be displaced axially, hydraulically or pneumatically, in the clamping-element guide (20) in relation to the valve guide (3) counter to the force of a spring element (14).
4. Internal combustion engine according to Claim 2 or 3, with at least two inlet valves and/or at least two outlet valves for each combustion space (5), characterized in that the clamping elements of in each case at least two of the inlet valves and/or of the outlet valves are connected to one another via a bridge element (19).
5. Internal combustion engine according to one of Claims 1 to 4, characterized in that the clamping element has at least one piezoelectric actuator (13) for the actuation of the clamping element.
6. Internal combustion engine according to Claim 5, characterized in that the clamping element is designed as a clamping ring (11) which circumferentially has a gap (12) in which the at least one piezoelectric actuator (13) is arranged in such a way that an excitation of the piezoelectric actuator (13) leads to an enlargement of the circumference of the clamping ring (11) and to a fixing of the clamping ring (11) in the clamping-element guide (20).
7. Internal combustion engine according to Claim 5, characterized in that the clamping element is designed as a clamping ring (11) which circumferentially has a gap (12) in which two clamping jaws (16) spaced apart from one another are arranged in such a way that an enlargement of the spacing (17) between the clamping jaws (16) leads to an enlargement of the circumference of the clamping ring (11) and to a fixing of the clamping ring (11) in the clamping-element guide (20), the at least one piezoelectric actuator (13) being arranged in the spacing (17) between the clamping jaws (16) in such a way that an excitation of the piezoelectric actuator (13) leads to an enlargement of the spacing (17) between the clamping jaws (16).
8. Internal combustion engine according to Claim 7, characterized in that the clamping jaws (16) are fixed in the axial direction in relation to the clamping-element guide (20).
9. Internal combustion engine according to Claim 5, characterized in that the clamping element is designed as a clamping ring (11), on which acts at least one clamping jaw (18) fixed in the axial direction in relation to the clamping-element guide (20), the said clamping jaws being displaceable radially inwards by means of the at least one piezoelectric actuator (13) in such a way that they act on the clamping ring (11) from outside.
10. Valve arrangement, comprising a valve guide (3) and a hydraulically or pneumatically actuable valve (4) guided in the valve guide (3), characterized in that the valve (4) can be fixed in relation to the valve guide (3) by means of an electrically actuable clamping element.
11. Valve arrangement according to Claim 10, characterized in that the valve (4) is designed as an inlet valve for the inlet of fuel or of a fuel/air mixture into a combustion space (5) of an internal combustion engine or as an outlet valve for the outlet of combustion exhaust gases from the combustion space (5).

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