EP1001143A2 - Valve control for intake and exhaust valves in internal combustion engines - Google Patents

Abstract

The valve controller has at least one control element with which the inlet/outlet valve is opened and closed. At least one piezo element (1) actuates at least one valve element (3) that controls the input and output flow of a pressurized medium to at least one control piston (15) that is displaced by the pressurized medium against a countering force to open the valve (30).

Description

The invention relates to a valve control for intake and exhaust valves of internal combustion engines according to the preamble of claim 1.

In conventional internal combustion engines, the Stroke movements of the intake and exhaust valves by one of the Crankshaft in the speed ratio 2: 1 driven camshaft. The Stroke curve of the valve is for the entire area of the map proportional to the cam profile and therefore unchangeable. The The closing point of the inlet valve is due to different ones Flow velocity in the intake manifold, not optimally placed. The The inlet or opening point can also not be optimally set. The values for the best possible filling of the combustion chamber at high speeds and the cylinder exhaust gas content at low Speeds and idle are diametrically opposed to each other. The opening point or start of the outlet is therefore usually chosen so that the expulsion losses are minimized and the gas in the Able to do maximum work.

To avoid the aforementioned polls, always compromise valve controls have been developed to control timing, Stroke curves of the intake and exhaust valves depending on the Motor speed, the load and other influencing factors influence and to be able to change. The course of the valve lift can be done by Variations in phase, valve lift or valve opening time be influenced or changed. Such measures can individually or in combination to be used on gasoline engines on the one hand to reduce fuel consumption and emissions and on the other hand to improve the torque curve and increase the maximum performance. Another advantage arises from the possibility of changing the amount of air sucked in to influence the valve opening cross-section and thus a throttle-free Allow load control without throttle.

With multi-valve technology, such a connection can be made be that the sucked charge flows only through an inlet valve and thus their amount is affected. A cylinder deactivation by influencing the intake and exhaust valves can also be realized, the fired cylinders by hiding of injections and combustion air in the best efficiency range can work. With modern engine electronics can switch the cylinder deactivation cyclically (selective) to the Avoid cooling the cylinder wall.

The aforementioned options for influencing and changing of parameters are called "variable valve timing" summarized. Depending on the type of valve actuation, between distinguish directly and indirectly operated systems.

Two solutions are known for the indirectly actuated systems, namely the use of a variable camshaft or a variable Intermediate element. With directly operated systems basically three ways are known in which the actuation of the valve is carried out hydraulically, pneumatically or electrically. A In these cases, camshaft is not required.

In the hydraulic system, the energy becomes similar to that of the so-called Common rail system saved and by fast magnet or Servo valves fed to or removed from the actuating piston surfaces, with which in turn the inlet and outlet valves are actuated. Such systems are for use in slow-running diesel engines known.

The invention has for its object the generic valve control to be designed so that instead of a complex servo valve simple and reliable operation at high switching frequencies is possible, so that the valve control for high-revving Internal combustion engines can be used.

This object is achieved according to the invention in the generic valve control with the characterizing features of claim 1 solved.

In the valve control system according to the invention, a control element is used piezoelectric actuator used. With it becomes a low-mass Valve element actuates the inflow and outflow of the pressure medium controls to and from the actuating piston, the stroke of which and exhaust valves of the internal combustion engine opened and closed become. Piezoelectric actuators set electrical voltages directly into paths and forces. Implementation of the electrical Input variable in a mechanical output variable takes place extremely fast. Adjustment stroke of for example 40 µm (0.04 mm) can be in a positioning time of 50 µs (0.000.05 sec). The dissolution of the Travel is in the nanometer range with suitable electrical control (0.0001 mm) possible. Actuating forces are in the kilonewton range reached, that is to say actuators with very high mechanical rigidity.

In the highly dynamic area, on the one hand, there is the availability of suitable ones Power amplifiers an essential requirement to the control process and the reaction of the intake and exhaust valves to synchronize. On the other hand, the flow cross section is at Dimension the seat valve accordingly large. This takes place at a advantageous embodiment of the valve control according to the invention by increasing the stroke to a value for which the available Travel of the piezoelectric transducer is not sufficient. It will therefore used travel enlarger, which is advantageous after Lever principle work and the usable travel of the valve element for example, can enlarge up to the factor ü = 10.

In the valve control according to the invention can be advantageous Way according to the engine management the opening and Closing times for the intake / exhaust valves the duration of the opening hours be determined as required.

Further features of the invention result from the further claims, the description and the drawings.

Fig. 1 bis 3

jeweils in schematischer Darstellung verschiedene Ausführungsbeispiele von erfindungsgemäßen Ventilsteuerungen, die mit konstantem Hub arbeiten,

Fig. 4

in schematischer Darstellung den Aufbau eines Hubübersetzers zwischen einem Piezoelement und einem Sitzventil der erfindungsgemäßen Ventilsteuerung,

Fig. 5

in schematischer Darstellung eine Ventilsteuerung durch Nockenwelle (ohne dargestellte Kipphebel) nach dem Stand der Technik,

Fig. 6 bis 8

jeweils in schematischer Darstellung weitere Ausführungsformen von erfindungsgemäßen Ventilsteuerungen, die mit variablem Hub arbeiten,

Fig. 9

einen Schnitt durch eine Ventilsteuerung mit Wirkprinzip entsprechend Fig. 1, jedoch mit zusätzlicher Hebelübersetzung,

Fig. 9a

in vereinfachter Darstellung einen Teil eines herkömmlichen Nockenwellenantriebs (ohne dargestellte Kipphebel),

Fig. 9b und 9c

in zwei Diagrammen den Hub eines Ventils eines Verbrennungsmotors in Abhängigkeit von der Zeit bei Einsatz der erfindungsgemäßen Ventilsteuerung,

Fig. 10

im Axialschnitt eine erfindungsgemäße Ventilsteuerung mit Wirkprinzip entsprechend Fig. 2, jedoch mit zusätzlicher Hebelübersetzung,

Fig. 11

in vergrößerter Darstellung einen Teil der Ventilsteuerung gemäß Fig. 10,

Fig. 12

im Axialschnitt eine erfindungsgemäße Ventilsteuerung mit Wirkprinzip gemäß Fig. 3, jedoch mit zusätzlicher Hebelübersetzung,

Fig. 13

eine Draufsicht auf eine erfindungsgemäße Ventilsteuerung mit Wirkprinzip entsprechend Fig. 6, jedoch mit zusätzlicher Hebelübersetzung,

Fig. 14

einen Schnitt längs der Linie XIV-XIV in Fig. 13,

Fig. 15

einen Schnitt längs der Linie XV-XV in Fig. 13,

Fig. 16 und 17

jeweils in vergrößerter Darstellung einen Teil der Ventilsteuerung gem. Fig. 14,

Fig. 18 bis 21

verschiedene Diagramme, die die Möglichkeit der Variierung des Ventilhubs, der Öffnungsdauer, der Phasenlage und der Kombination dieser Parameter zeigen.

The invention is explained in more detail with the aid of some exemplary embodiments shown in the drawings. Show it

1 to 3

in each case in a schematic representation different exemplary embodiments of valve controls according to the invention, which operate with a constant stroke,

Fig. 4

a schematic representation of the construction of a stroke translator between a piezo element and a seat valve of the valve control according to the invention,

Fig. 5

a schematic representation of a valve control by camshaft (without shown rocker arm) according to the prior art,

6 to 8

each in a schematic representation of further embodiments of valve controls according to the invention, which work with a variable stroke,

Fig. 9

2 shows a section through a valve control with the operating principle according to FIG. 1, but with additional lever transmission,

Fig. 9a

a simplified representation of part of a conventional camshaft drive (without shown rocker arm),

9b and 9c

in two diagrams the stroke of a valve of an internal combustion engine as a function of time when using the valve control according to the invention,

Fig. 10

in axial section a valve control according to the invention with the operating principle corresponding to FIG. 2, but with additional lever transmission,

Fig. 11

in an enlarged view part of the valve control according to FIG. 10,

Fig. 12

in axial section a valve control according to the invention with the operating principle according to FIG. 3, but with additional lever transmission,

Fig. 13

6 shows a top view of a valve control according to the invention with the operating principle corresponding to FIG. 6, but with additional lever transmission,

Fig. 14

12 shows a section along the line XIV-XIV in FIG. 13,

Fig. 15

a section along the line XV-XV in Fig. 13,

16 and 17

each in an enlarged view part of the valve control acc. Fig. 14

18 to 21

various diagrams showing the possibility of varying the valve lift, the opening time, the phase position and the combination of these parameters.

1 to 8 different embodiments described by valve controls in their mode of operation. 9 to 21 then show specific configurations of such valve controls and associated characteristics.

The valve controls described below enable high Control frequencies, so that these valve controls even at high revs Internal combustion engines can be used.

1 has a piezo element as an actuator 1, whose plunger 2 acts on a valve element 3, which acts as a valve ball is trained. The valve element 3 lies in a valve chamber 4 of a valve housing 5. The valve element 3 is under the force a compression spring 6 with which the valve element 3 when the piezo element is de-energized 1 is held in a closed position. The valve element 3 is by the compression spring 6, which is a conical helical compression spring is pressed up against the valve seat. In this In the closed position, the valve element 3 closes a pressure line 7, supplied via the hydraulic medium from a pressure source 8 becomes. The valve element 3 and the valve chamber 4 are part of one Two-way seat valve 9, to which a supply line 10 for hydraulic medium connected. It has at least one restriction 11 provided. A tank line 12 opens into the feed line 10 which is also a throttle point 13. The feed line 10 connects the valve chamber 4 with a pressure chamber 14 in the valve housing 5 is provided and in which there is an actuating piston 15, the an end face 16 can be acted upon by hydraulic medium. On the side opposite the pressure chamber 14 is located Cylinder chamber 17, which has at least one opening 18 with the atmosphere connected is. A plunger 19 projects into the cylinder space 17 cooperates with a tappet 20. He is under the force at least one compression spring 21 which via a valve stem 22 Cup tappet 20 and thus the bolt-shaped tappet 19 in the direction loaded on the actuating piston 15 (see also Fig. 9). On the tappet 20 is applied to the valve stem 22, the one with a free end Valve plate 23 is provided. With it is an inlet or outlet opening 24 of a combustion chamber 25 of an internal combustion engine 26 of a motor vehicle opened and closed.

In the position shown in FIG. 1, the piezo element 1 has no current, so that the plunger 2 is retracted. The valve element 3 lies under the force of the compression spring 6 on its valve seat and closes the pressure line 7. Under the force of the compression spring 21 is on the Valve stem 22 of the tappet 20 and thus the tappet 19 in Direction loaded on the actuating piston 15. This is through the plunger 19 moved until the valve plate 23 of the intake / exhaust valve of the internal combustion engine 26, the inlet / outlet opening 24 of the Combustion chamber 25 closes. In this position the Two-way seat valve 9 facing end face 16 of the actuating piston 15 Distance from the bottom 27 of the pressure chamber 14 into which the feed line 10 opens.

The piezo element 1 is controlled by a control (not shown) energized by its plunger 2, the valve element 3 against Force of the compression spring 6 is lifted off the valve seat. The hydraulic medium can then via the pressure line 7, the valve chamber 4 and the Flow supply line 10 into the pressure chamber 14. Part of this hydraulic medium flows over the tank line 12, which is in the range between the valve chamber 4 and the pressure chamber 14 to the supply line 10 connects to the tank. The two throttle points 11, 13 in the feed line 10 and in the tank line 12 are thus one on the other matched that in the pressure chamber 14 by the hydraulic medium pressure required to move the actuating piston 15 is applied can be. The caused by the required pressure Force must be greater than that of the compression spring 21 on the tappet 20 exerted counterforce so that the actuating piston 15 against the Force of the compression spring 21 is shifted, with the plunger 19, the tappet 20 and the valve stem 22 of the valve plate 23 in its open position is postponed. The adjusting piston 15 is so far moved until it with its end face 28 at the bottom 29 of the cylinder space 17 strikes. In this way the inlet / outlet opening Open 24.

If the piezo element 1 is de-energized again, the valve element 3 under the force of the spring 6 in its closed position according to FIG. 1 returned. As a result, the pressure medium supply from line 7 locked to the pressure chamber 14, and the compression spring 21 can now Push the tappet 20 and the tappet 19 against the setting piston 15 and this towards the 2-way poppet valve 9. Thereby the pressure medium located in the pressure chamber 14 via the Line 10, the throttle 13 and line 12 displaced to the tank. If the actuating piston 15 assumes its initial position according to FIG. 1, the valve disk 23 closes the inlet / outlet opening 24 of the combustion chamber 25th

The piezo element 1 can be operated at a very high frequency, so that the opening and closing process described Intake / Auslassventils 30 take place in the required high control frequency can. The valve control is therefore for internal combustion engines suitable that work at high speeds. On the described All of the valves 30 of the internal combustion engine 26 are actuated in this manner.

The inlet / outlet valve 30 is in the open position and in the closed position each over a period of time specified by the engine management held. This results in the inlet / outlet valve 30 four cyclically repeating operating states, namely opening, keep open, close and keep closed.

Fig. 9 shows a concrete embodiment of the embodiment 1. The piezo element 1 is located in the valve housing 5 next to the Adjusting piston 15 and the valve element 3. The piezo element 1 is in a receiving space 31 of the valve housing 5 and is by springs 32, preferably biased by disc springs, in the receiving space 31. The piezo element 1 acts with a two-armed lever 33 together, which is pivotally mounted in a housing space 34. One lever arm interacts with the piezo element while on the other lever arm, the tappet 2 actuating the valve element 3 engages an adjusting screw 82. The stroke positions can be done with it of the piezo element 1 and the plunger 2 match each other. The plunger 2 is guided by a bearing 35 so that it is reliable can be moved.

The actuating piston 15 is located in the area between the two-way seat valve 9 and the piezo element 1. The piezo element 1 is energized and thus elongated, the lever 33 is perpendicular to its Axis of the piezo element 1 lying axis 36 counterclockwise pivoted. This pushes the plunger 2 downwards whereby the valve element 3 against the force of the compression spring 6 is moved to the open position. The pressure line 7 will opened so that the pressurized hydraulic medium over the Throttle point 11 can flow into the pressure chamber 14. The actuating piston 15 is thereby moved down. About the plunger 19 and the Cup tappet 20 becomes the valve stem 22 against the force of the compression spring 21 moved so that the valve plate 23 lifts off the valve seat and exposes the inlet / outlet opening 24 into the combustion chamber 25. In this open position, the piezo element remains in accordance with the Motor management energized. In this static operation there is a almost powerless holding of the actuated piston position 15 possible. As soon as the piezo element is de-energized again and thereby shortened, the valve element 3 by the Compression spring 6 moves into its closed position and the connection of the pressure line 7 to the pressure chamber 14 interrupted. The pressure room 14 is now only on the throttle 13 with the tank in Connection. About the plunger 2, the lever 33 is clockwise pivoted about the axis 36. The swivel movement ends with the Closing the valve element 3. The valve stem 22 is through the Compression spring 21 moved upwards, causing the tappet 20 and the plunger 19 of the piston 15 is moved upwards. The hydraulic medium located in the pressure chamber 14 is via the Throttle point 13 and the tank line 12 in the manner described displaced to the tank. The piezo element remains in this closed position de-energized according to engine management.

The tappet 20 is located in a receiving space 37 of the Internal combustion engine 26. The valve housing 5 is on the internal combustion engine 26 attached. The receiving space 37 is through the valve housing 5 closed.

Since the piezo element 1 in the area next to the two-way seat valve 9 and the control piston 15 is arranged, the valve housing 5 only a low overall height. This is helped by the fact that the adjusting piston 15 is arranged in the area next to the two-way seat valve 9. The lever 33 serves as a translation lever, which the very small ways of Piezo element 1 over the longer lever arm in sufficiently large Ram 2 displacement paths translated.

9a shows a conventional valve control by means of a camshaft 39. For the sake of clarity, it is between the camshaft 39 and tappet 20 lying rocker arm not shown. The cams 40 of the camshaft 39 act with the tappets 20 the inlet / outlet valves together in a known manner. The one through the Cam 40 achieved stroke of the valve stem 22 has the same size as in the described valve control according to FIGS. 1 and 9.

Fig. 9b shows with solid lines that with the camshaft Valve control opens the inlet / outlet valve 30 faster and can be closed than with the conventional camshaft control (dashed line in Fig. 9b). With the dotted line the possibility is shown with the camshaft-less valve control to vary the opening duration of the intake / exhaust valve 30. Fig. 9c shows the possibility in the camshaft-less valve control also the phase position (solid and dotted line) and also vary the opening time (dotted line).

2 and 10 show a valve control, which compared to Embodiment according to FIGS. 1 and 9 higher control frequencies allows. The valve 9 'is different from the previous embodiment a three-way valve with two seats. Fig. 2 again shows the State with de-energized piezo element 1. The valve element 3 lies under the force of the compression spring 6 on an upper valve seat 41 (Fig. 11). In contrast to the previous one, the tank line 12 opens out Embodiment in a lower valve seat 42 of the three-way valve 9 '. Fig. 11 shows the three-way valve of Fig. 10 in an enlarged view Presentation.

To open the inlet / outlet valve 30, the piezo element 1 is energized and thereby expands. The two-armed lever 33 will thereby pivoted counterclockwise about axis 36, whereby the plunger 2 downwards against the force of the compression spring 6 is moved until it rests on the lower valve seat 42. Thereby the tank line 12 is closed, so that the pressure line 7 flowing medium exclusively via the feed line 10 in reaches the pressure chamber 14. As a result, the end face 16 of the actuating piston 15 pressurized with pressure medium so that it is described in the Way is moved down and over the plunger 19 and the tappet 20 moves the valve stem 22. Thereby the inlet / outlet valve 30 is opened in the manner described and kept in the open position if necessary.

To close the inlet / outlet valve 30, the piezo element 1 de-energized and shortened to its original length. The valve element 3 becomes the upper valve seat by the compression spring 6 41 moved, which closed the pressure line 7 and the Tank line 12 is opened. This can cause the hydraulic medium from the pressure chamber 14 via the feed line 10 into the tank line 12 stream. The pressure relief of the pressure chamber 14 will Inlet / outlet valve 30 closed in the manner already described and kept in the closed position if necessary.

The lower valve seat 42 of the three-way valve 9 'is on one Insert 43 provided (Fig. 11), which in turn in another Insert 44 is held. It is in an installation space 45 of the Valve housing 5 pressed. The free end of the insert 44 is flanged inwards, whereby the insert located in it 43 is held.

The three-way valve 9 'forms a shuttle valve. The valve element 3 has accordingly two seat parts 83 and 85, with which it alternates abuts the upper valve seat 41 and the lower valve seat 42. The upper seat part 83 is in the illustrated embodiment partially spherical, but can also have a conical shape. The seat part 83 is approximately hemispherical. An approach 84 connects to it to which the compression spring 6 is pushed with its upper end is. The approach 84 widens conically from the upper seat part 83. At the transition from the neck 84 in the upper seat part 83 is a Stage formed. The diameter difference between the approach 84 and the seat part 83 corresponds to twice the wire thickness of Compression spring 6. As a result, the upper end of the compression spring 6 does not stand radially over the seat part 83. Because the approach 84 is conical is, the compression spring 6 has a conical shape. The compression spring 6 is with its upper end region on the jacket of the neck 84. Since the Approach 84 and the compression spring 6 are conical and expand from the seat part 83 is an axial lock for the compression spring 6 given on the approach 84. This will assemble this Valves 9 'relieved. The lower seat part 85 is again part-spherical trained and has a maximum diameter that the corresponds to the maximum diameter of the extension 84. The seat part 85 can also be conical. The largest diameter of the Approach 84 or the lower seat part 85 is smaller than the largest Diameter of the upper seat part 83. Accordingly, the lower one Seat part 85 has a smaller seat diameter than the upper seat part 83, so that the upper valve seat 41 has a larger diameter than that lower valve seat 42. The upper valve seat 41 is axial from the tappet 2 permeated. The resulting ring surface 81 (Fig. 11) of the Upper valve seat 41 is approximately the same area as the circular area 88 (Fig. 11) of the lower valve seat 42. The valve element 3 can manufacture themselves inexpensively from a sphere. In this case the upper and lower seat portions 83, 85 share a common curvature.

The valve control according to FIGS. 2, 10 and 11 is otherwise the same formed like the previous embodiment (Fig. 1 and 9). However can with this valve control the intake / exhaust valves even faster can be opened and closed like the corresponding diagrams show below Fig. 11 (solid and dotted lines). In comparison, the closing and Opening times of conventional camshaft valve controls are shown. As already explained with reference to FIGS. 9b and 9c, the Phase position and the opening time can be changed in the same way.

3 and 12 show a valve control with end position damping of the control piston 15. The valve control has the piezo element 1, with which the plunger 2 for actuating the valve element 3 in the described Way is moved. The connection between the Piezo element 1 and the plunger 2 takes place in a specific embodiment (Fig. 12) again via the two-armed lever 33, with which the plunger 2 is displaced when the piezo element 1 is energized is and the valve element 3 moves accordingly. The Valve 9 "is in accordance with the previous embodiment (Fig. 11) designed as a three-way valve with two valve seats. Is the piezo element 1 is not energized, the valve element 3 is under the force the compression spring 6 on the upper valve seat 41. The pressure line 7 is thereby separated from the feed line 10. If the piezo element 1 energized, the lever 33 is counterclockwise around its Axis 36 pivoted, whereby the plunger 2 is moved and the valve element 3 lifts off the upper valve seat 41 until it is at the lower Valve seat 42 abuts. This allows the hydraulic medium from the Pressure line 7 reach the supply line 10 via the valve chamber 4. A transverse line 46 branches off from the feed line 10, in the one check valve opening in the direction of the actuating piston 15 47 sits. The cross line 46 opens into the pressure chamber 14.

The end face 16 of the actuating piston 15 has a throttle cross section 48 provided that in the exemplary embodiment as a diametrically extending is formed triangular recess in cross section. Also the opposite end face 28 of the actuating piston 15 is with a Throttle cross section 49 provided, which is also advantageous as in Cross-section of triangular, diametrically extending recess is. The actuating piston 15 lies with its end face 28 as in the previous embodiments on the plunger 19, the corresponding the previous embodiments a smaller cross section has as the end face 28 of the actuating piston 15. About the Tappet 19, the tappet 20 and the valve stem 22 in the described way postponed.

The feed line 10 opens into an annular channel 50 which is in the wall of the piston chamber 51 is provided. Another ring channel 52 in the wall of the piston chamber 51 is provided in the cylinder chamber 17. This ring channel 52 is connected via a return line 53 the tank line 12 connected. The cylinder space 17 is over a Cross line 54 connected to a check valve 55, which the Cross line 54 separates from the return line 53 and that in the direction opens on the cross line 54.

To open the inlet / outlet valve 30, the piezo element 1 is energized. The plunger 2 is moved via the lever 33, whereby the valve element 3 is lifted from the seat 41 and on the opposite Valve seat 42 is brought into contact. This will make the Pressure line 7 opened so that the hydraulic medium via the valve chamber 4, the feed line 10, the transverse bore 46 and the check valve 47 can flow into the pressure chamber 14. Because the valve element 3 rests on the valve seat 42, the connection to the tank line 12 closed. The hydraulic medium passes through the supply line 10 also in the annular channel 50, which is initially through the actuating piston 15 is closed. The adjusting piston 15 is in the Pressure chamber 14 flowing hydraulic medium shifted downwards. In contrast to the two previous embodiments hydraulic medium in the lower cylinder chamber 17. It will be when moving of the actuating piston 15 via the ring channel 52 and the return line 53 displaced into the tank line 12. The end face 28 is located initially at a distance from the ring channel 52. Runs over the control piston 15 with its end face 28, the control edge 56 of the Ring channel 52, the throttle cross-section 49 comes in the piston face 28 in operative connection with the ring channel 52. Because the deepening 49 steadily enlarged in the direction of the piston face 28, occurs when the actuating piston 15 moves downward after being run over the control edge 56 due to the increasingly smaller effective Throttle cross-section and the closed check valve 55 a throttling effect, which contributes to a damping effect the downward movement of the actuating piston 15 leads. Because of this steadily decreasing flow cross-section for the hydraulic medium builds up a pressure in the medium in the cylinder chamber 17, the counteracts the downward movement of the actuating piston 15 and so the Damping caused by speed reduction. The check valve 55, which via the cross line 54 with the cylinder space 17th is connected, closes against the return line 53 and thus the Tank line 12.

To close the inlet / outlet valve 30, the piezo element 1 switched off again and thus shortened. The valve element 3 is by the compression spring 6 in the manner described from the valve seat 42 lifted off and pressed against the valve seat 41. Thereby the pressure line 7 is closed against the supply line 10. At the same time, the tank line 12 is thus opened. About the compression spring 21 are the valve stem 22 and the tappet 20 upwards postponed. The actuating piston 15 is carried along via the tappet 19. It displaces the hydraulic medium from the pressure chamber 14 in the ring channel 50, through which the hydraulic medium via the valve chamber 4 reaches the tank line 12. Once the piston face 16 passes over the control edge 57 (FIG. 12) of the ring channel 50, the Throttle cross section 48 in the piston face 16 in operative connection with the control edge 57 of the ring channel 50. With increasing upward stroke becomes the throttle cross section for the flow of the hydraulic medium steadily reduced in the ring channel 50, resulting in Pressure chamber 14 builds up a pressure which corresponds to the upward movement of the Actuating piston 15 counteracts and causes the damping. The check valve 47 prevents the hydraulic medium during the upward stroke of the actuating piston 15 from the pressure chamber 14 into the feed line 10 arrives.

The described embodiment is advantageous in this that the actuating piston 15 is damped in both end positions. Thereby this valve control works very quietly. The three-way valve 9 "is otherwise the same as in the previous Embodiment. The three-way valve is also in this valve control 9 ", the actuating piston 15 and the piezo element 1 at a distance next to each other in the valve housing 5. This only has one low height.

1 to 3 schematically show, it is also possible to Tappet 2 to be actuated directly by the piezo element 1, so that a translation lever 33 is omitted. The use of a translation lever has the advantage that, depending on the gear ratio, the stroke of the valve element 3 can be enlarged. This allows different Flow cross sections can be achieved.

As a comparison of FIGS. 3 and 5 shows, the valve controls 1 to 3 or 9 to 12 the same stroke 80 is reached as when using a conventional camshaft control (Fig. 5). This means that the camshaft-less valve control can be used instead the camshaft valve control.

4 schematically shows the possibility of using the piezo element 1 via a plunger 58 to a one-armed transmission lever 59 Act. The plunger 58 engages at a distance 60 from a pivot axis 61 on lever 59. The free end of the lever 59 acts the plunger 2 with which the valve element 3 in the described Way is moved. The free end of the lever has a distance of 62 from the pivot axis 61. The two distances 60, 62 desired gear ratio determined.

In the exemplary embodiments described above, the actuating piston stroke is and thus the stroke of the intake / exhaust valve 30 cannot be changed.

6 and 13 to 21 show an embodiment in which this Valve stroke can be changed. The valve control has two piezo elements 1, 1a, with which two plungers 2, 2a are operated in order to move two valve elements 3, 3a of two seat valves 9, 9a. The two valve elements 3, 3a are each at least under the force a compression spring 6, 6a. In the valve chamber 4a of the seat valve 9a opens the pressure line 7. When the piezo element 1a is de-energized the pressure line 7 via the closed valve element 3a from the Supply line 10 separated, which opens into the pressure chamber 14. Of the Feed line 10 branches off a connecting line 63, which in the Valve chamber 4 of the seat valve 9 opens. When the piezo element is not energized 1, the valve chamber 4 is connected to the tank line 12.

Fig. 6 shows the situation when the two piezo elements 1, 1a de-energized and thus the inlet / outlet valves 30 are closed. Should the intake / exhaust valve 30 perform the maximum opening stroke (Normal stroke and overstroke), both piezo elements 1, 1a are energized. As a result, the two plungers 2, 2a are displaced. With the Tappet 2, the valve element 3 against the force of the spring 6 in its Moves the closed position in which it closes the tank line 12. With the plunger 2a, the valve element 3a is in an open position moves so that the hydraulic medium via the pressure line 7 and Valve chamber 4a can flow into the feed line 10. The hydraulic medium thereby enters the pressure chamber 14 and shifts the Set piston 15 down. About the plunger 19 and the cup tappet 20 the valve stem 22 is displaced and in this way the Inlet / outlet valve 30 opened. The setting piston 15 is shifted so far until he on the bottom 29 of the cylinder chamber 17 to the system is coming. This corresponds to the stroke of the actuating piston 15 and thus the Valve 30 the normal stroke plus an excess stroke.

If the engine management requires it, the actuating piston 15 and thus the valve 30 only around the normal or everyone any other stroke can be adjusted. For this purpose, both piezo elements 1, 1a energized and the piezo element 1a after a stroke-determining Time de-energized so that the valve element 3a moved into its closed position by the force of the compression spring 6a becomes. As a result, the pressure line 7 is separated from the supply line 10. At the same time, the piezo element 1 remains energized and thereby the valve 3 closed and the volume in the pressure chamber 14 chambered. That is now less compared to the previous process Liquid volume of the hydraulic medium flowing into the pressure chamber thus determines the stroke of the actuating piston 15 and thus also the stroke of the inlet / outlet valve 30, since the piezo element 1 continues to be energized, thereby closing line 63 to tank 12 remains. The volume of liquid in the pressure chamber 14 thereby remains enclosed (chambered), the valve 30 less wide open, so that a correspondingly smaller amount of Air-fuel mixture in the combustion chamber of the internal combustion engine reached.

If the inlet / outlet valve 30 is to be closed, the piezo element 1 switched off. The compression spring 6 lifts the valve element 3 from its valve seat 66, whereby the pressure chamber 14 located hydraulic medium via the feed line 10 and the open Valve chamber 4 can be displaced into the tank line 12.

16 and 17 show, the valve element 3 and the Compression spring 6 in a socket 64, which is in an installation space 65 of the Valve housing 5 is pressed. The one provided for the valve element 3 Valve seat 66 is provided on insert 43, which is essentially is of the same design as in the embodiment according to 10 and 11. The compression spring 6 maintains the valve element 3 non-energized piezo element 1 in the open position, which is shown in FIG is shown. The insert 43 is through the flanged end 67 of the sleeve 64 axially secured. A central axial bore 68 of the insert 43 is preferably by a closure element 69 a ball, closed.

The valve element 3a is also received in a bushing 70 (Fig. 16), the lower end 71 is crimped. The valve element 3a is pushed up against a valve seat 72 by the compression spring 6a pressed, the plunger 2a penetrates axially and thus one for the Flow required ring area 81 generated.

The two seat valves 9, 9a are located on both sides of the actuating piston 15 and axially parallel to it. As a result, the valve housing 5 has only one low axial height.

The cylinder chamber 17 is, as shown in FIG. 14, via the ventilation line 18 connected to the atmosphere, so that the actuating piston 15 to Opening the intake / exhaust valve 30 can be reliably moved can.

To open the inlet / outlet valve 30, both piezo elements 1, 1a energized. The size of the stroke of the actuating piston 15 and thus of the intake / exhaust valve 30 depends on the time after the start of opening the piezo element 1a is no longer energized and thus no more hydraulic medium can flow into the pressure chamber 14. Depending on the energization time of the piezo element 1 a leaves thus control the stroke of the intake / exhaust valve 30 continuously.

For the closing movement of the intake / exhaust valve 30, like this 3 and 12 has been explained, a damping is provided his. In this case, it is of the same design as this one Embodiment.

In the described exemplary embodiments, in contrast to a camshaft control the phase position with respect to the opening and closing the intake / exhaust valves 30. This is possible that the associated with the intake / exhaust valves 30 Piezo elements can be energized or de-energized at the desired time. 6 and 13 to 17 can in the manner described also the size of the opening stroke of the intake / exhaust valve 30 can be varied.

18 shows characteristic curves of the stroke based on the exemplary embodiment 6 and 14 to 17 described possibility of opening stroke of the intake / exhaust valve 30 to vary.

Fig. 19 shows on the basis of characteristic curves that the opening duration of the Inlet / outlet valves 30 can be changed in the manner described can. From the characteristics in Fig. 20 it follows that additionally the phase position can be set in the manner described. 21 shows characteristic curves for the exemplary embodiment 6 and 13 to 17, in which the three setting options 18 to 20 can be used in combination. The valve lift, the duration of the opening and the phase position to be changed. This embodiment represents one fully variable control of the inlet / outlet valves 30.

The plungers 2, 2a can be actuated directly by the piezo elements 1, 1a as shown schematically in Fig. 6. But it is also possible between the plunger 2, 2a and the piezo element 1, 1a each provide a transmission lever 59, 59a to the Opening and closing stroke of the valve element 3, 3a at a predetermined Magnify Piezohub. In the schematically illustrated embodiment 7 are the transmission levers 59, 59a one-armed lever. At a distance 60 from the pivot axis 61, 61a Lever 59, 59a engages the plunger 58, 58a in accordance with the Embodiment according to FIG. 4. At the free end of the lever 59, 59a, which is at a distance 62 from the respective pivot axis 61, 61a is located, the plunger 2, 2a attacks. As with the embodiment 4, the plungers 2, 58 and 2a, 58a lie on each other opposite sides of the lever 59, 59a. About the relationship of the distances 60 and 62 to each other can be the gear ratio be determined.

In the embodiment according to FIG. 8, the levers 33, 33a have two arms Levers that have lever arms 86, 87 of different lengths. The plungers 58, 58a of the piezo elements engage on the shorter lever arm 87 1, 1a. The levers 33, 33a engage on the same side the plungers 2, 2a to the free ends of the longer lever arms 86. About the ratio of the length of the lever arms to each other also determine the gear ratio.

Since the two plungers 2, 58; 2a, 58a lie on the same side of the levers 33, 33a, one results low height 73. The two-armed levers 33, 33a lie like this based on the embodiment of FIGS. 13 to 17 in detail is explained, spatially offset from each other, so that the valve housing 5 has only correspondingly small dimensions.

In the embodiment according to FIG. 7, the overall height is greater than that of Embodiment according to Fig. 8, because the piezo elements 1, 1a with their plungers 58, 58a on one and the plungers 2, 2a with the Valves 9, 9a sit on the other side of the levers 59, 59a. In Fig. 7 is the overall height of the piezo elements 1, 1a with the plungers 58, 58a with 74 and the height of the seat valves 9, 9a with the tappets 2, 2a and the pivot levers 59, 59a at 75. It is recognizable that the overall height 74, 75 is about twice as large as the total height 73 in the exemplary embodiment according to FIG. 8.

In the embodiment according to FIGS. 6 and 13 to 17, the two two-armed levers 33, 33a in the housing space 34, which by a housing cover 76 is closed. The two levers 33, 33a are staggered and are each under one acute angle to a longitudinal center plane 77 of the valve housing 5. Seen in side view, the two levers 33, 33a lie one against the other overlapping with a short distance behind each other. The swivel axes 36, 36a are parallel to each other. At the free end of the shorter one Lever arms engage the plungers 58, 58a of the two piezo elements 1, 1a. The tappets are located on the free ends of the longer lever arms 2, 2a with which the valve elements 3, 3a in the described Way to be operated.

The two piezo elements 1, 1a are located in separate housing spaces 78, 79 (Fig. 15). In the area between the two housing rooms 78, 79 is the cylinder space 17 with the piston 15 the ratio of the length of the lever arms of the respective lever 33, 33a, the gear ratio is determined. In this way can easily the small movement path of the piezo-side Tappet 58, 58a in the required adjustment path of the tappet 2, 2a be translated reliably to the respective valve element 3, 3a with the required stroke in the corresponding open or To move the closed position.

Claims (29)

Valve control for intake and exhaust valves of internal combustion engines, with at least one control element with which the intake / exhaust valve is opened and closed,
characterized in that the valve control has at least one piezo element (1, 1 ', 1a) with which at least one valve element (3, 3a) is actuated, which controls the inflow and outflow of a pressure medium to at least one actuating piston (15) which by means of the pressure medium against a counterforce for opening the inlet / outlet valve (30). Valve control according to claim 1,
characterized in that the valve element (3, 3a) is part of a seat valve (9, 9 ', 9a) which controls the inflow of the pressure medium from a pressure line (7) to the actuating piston (15). Valve control according to claim 2,
characterized in that the seat valve (9, 9 ') can be connected via a supply line (10), which is advantageously connected to a tank line (12), to a pressure chamber (14) which is delimited by the actuating piston (15), and that preferably the supply line (10) and / or the tank line (12) are provided with a throttle point (11, 13). Valve control according to one of claims 1 to 3,
characterized in that the actuating piston (15) interacts via a tappet (19) with a valve stem (22) of the inlet / outlet valve (30) which advantageously interacts with the tappet (19) via a cup tappet (20). Valve control according to one of claims 1 to 4,
characterized in that the cylinder space (17) opposite the pressure space (14) is connected to the atmosphere via the connection (18). Valve control according to one of claims 1 to 5,
characterized in that the feed line (10) can be connected to the tank line (12) via at least one seat valve (9, 9 '). Valve control according to one of claims 1 to 6,
characterized in that the movement of the actuating piston (15) is damped in at least one, preferably in both end positions. Valve control according to claim 7,
characterized in that the actuating piston (15) has at least one throttle cross-section (48, 49), preferably a diametrically extending depression, in at least one, preferably in both end faces (16, 28), and that advantageously the throttle cross-section (48, 49) An annular channel (50, 52), which can be connected to the tank line (12), is assigned in the wall of the actuating piston installation space (51). Valve control according to claim 8,
characterized in that when a control edge (56, 57) of the annular channel (50, 52) is passed over by the end face (16, 28) of the actuating piston (15) in accordance with the decreasing passage cross-section, a pressure in the pressure chamber (15) opposing the movement of the actuating piston (15) 14) or in the cylinder space (17), which can advantageously be closed against the tank line (12) by a check valve (47, 55). Valve control according to one of claims 1 to 9,
characterized in that between the piezo element (1, 1 ', 1a) and the tappet (2, 2', 2a) cooperating with the valve element (3, 3 ', 3a) there is a translator (33, 33') advantageously designed as a pivotable lever ; 59, 59a) is provided. Valve control according to claim 10,
characterized in that the lever (33, 33 ') is constructed with two arms, the piezo element (1, 1a) and the plunger (2, 2a) advantageously engaging on one arm of the lever (33, 33a) on the same side. Valve control according to claim 10,
characterized in that the lever (59, 59a) is constructed with one arm, the piezo element (1, 1a) and the plunger (2, 2a) advantageously engaging the lever (59, 59a) on opposite sides. Valve control according to one of claims 1 to 12,
characterized in that two piezo elements (1, 1a) are provided, with which two seat valves (9, 9a) can be actuated, which are preferably connected to a common supply line (10) for pressure medium, which opens into the pressure chamber (14). Valve control according to claim 13,
characterized in that in the case of de-energized piezo elements (1, 1a) the one seat valve (9) is open and the other seat valve (9a) is closed, and in that preferably the valve element (3) of the open seat valve (9) by the plunger (2) of a piezo element (1), when energized, is adjustable into its closed position, in which the feed line (10) is separated from the tank line (12). Valve control according to claim 14,
characterized in that the valve element (3a) of the closed seat valve (9a) can be adjusted into its open position by the plunger (2a) of the other piezo element (1a) when it is energized, in which the pressure line (7) communicates with the pressure chamber (14 ) opening supply line (10) is connected. Valve control according to one of claims 13 to 15,
characterized in that when both piezo elements (1, 1a) are energized over time, the actuating piston (15) and thus the driven inlet / outlet valve (30) executes its maximum stroke and can be held there. Valve control according to claim 16,
characterized in that both seat valves (9, 9a) are closed to hold the actuating piston (15) in the maximum open position. Valve control according to claim 16,
characterized in that to hold the actuating piston (15) in the maximum open position, one seat valve (9) is closed and the other seat valve (9a) is opened. Valve control according to one of claims 13 to 15,
characterized in that when the two piezo elements (1, 1a) are energized for a shorter period of time, the actuating piston (15) executes a stroke which is smaller than in the maximum stroke, and that both seat valves (9, 9a) are advantageous for holding the actuating piston (15) with a reduced opening stroke getting closed. Valve control according to one of claims 13 to 19,
characterized in that the two piezo elements (1, 1a) each interact with the plungers (2, 2a) via a translator (33, 33a), preferably a two-armed lever. Valve control according to claim 20,
characterized in that the two translators (33, 33a), viewed in the direction of their pivot axes (36, 36a), are arranged to overlap one another. Valve control according to claim 20,
characterized in that the two translators (33, 33a) are in series Valve control according to one of claims 20 to 22,
characterized in that the two boosters (33, 33a) are parallel to one another and advantageously at an acute angle to a longitudinal center plane (77) of a valve housing (5). Valve control according to one of claims 2 to 23,
characterized in that the seat valve (9 ') is a shuttle valve. Valve control according to one of claims 1 to 24,
characterized in that the valve element (3, 3a), which is advantageously made of a ball, has a seat part (83) which is preferably partially spherical or conical and from which a shoulder (84) with a smaller cross section projects. Valve control according to claim 25,
characterized in that the compression spring (6, 6a) is slid onto the extension (84) of the valve element (3, 3a) which advantageously widens conically from the seat part (83). Valve control according to claim 25 or 26,
characterized in that at the transition from the shoulder (84) to the seat part (83) the diameter difference corresponds to twice the wire thickness of the compression spring (6, 6a). Valve control according to one of claims 25 to 27,
characterized in that a further, preferably partially spherical or conical seat part (85) is provided at the free end of the extension (84). Valve control according to claim 28,
characterized in that the further seat part (85) has a smaller seat diameter than the other seat part (83).

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