JP3857081B2 - Method of operating an exhaust valve for an internal combustion engine and the exhaust valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides that the exhaust valve is opened by a spool of a control valve that is longitudinally displaced so that the high pressure port can be connected to a first pressure chamber in the actuator, and the actuator piston, together with the exhaust valve spindle, A method for operating an exhaust valve for an internal combustion engine, wherein the control valve spool is displaced longitudinally so as to connect the low pressure port with a first pressure chamber when displaced toward an open position and the exhaust valve is to be closed .
[0002]
[Prior art]
Such an exhaust valve is known from U.S. Pat. No. 3,209,737, in which the control valve is actuated by a cam on a camshaft or electronically by a solenoid valve. The control valve continuously connects the first pressure chamber with the high pressure port during the opening operation of the exhaust valve, and continuously connects the first pressure chamber with the low pressure port during its closing operation. Thus, the movement of the exhaust valve is controlled by the hydraulic pressure level and by the time that the pressure is applied to the working piston (having both open and closed areas). In practice, the control valve has only one position for opening the exhaust valve and one position for closing the exhaust valve, and when the hydraulic pressure acting on the actuator piston initiates movement of the spindle, the control valve opens and closes. Control is performed at the start of the closing operation, whereby the operation continues while the control valve remains in the open position. During operation, the hydraulic pressure can change and the operating speed of the spindle can fluctuate. The exhaust valve is controlled to operate optimally at a particular engine load, such as full load, and its opening speed does not change according to the engine speed, so this exhaust valve is not subject to other engine loads. Sometimes do not open at the optimal timing. The braking action of the spindle during the final part of the closing action is achieved by squeezing hydraulic fluid through the gap formed by the pin on the spindle that is pushed into the hole in the stationary housing.
[0003]
[Problems to be solved by the invention]
It is an object of the present invention to provide a method for more accurately controlling an exhaust valve, including control during its operation.
[0004]
[Means for Solving the Problems]
In view of this, the present invention is that the exhaust valve spindle is proportionally displaced in the longitudinal direction at a ratio such as a ratio of 1: 1 with the longitudinal displacement of the control valve spool. The spindle can be placed in a selected position between a fully open position and a fully closed position, and the exhaust valve spindle is substantially simultaneously with the control valve spool. And moving between the closed position.
[0005]
As a result of the proportional displacement of the spindle with the spool in the longitudinal direction, any adjustment of the spool is transferred to the corresponding movement of the exhaust valve. For this reason, there is a direct correlation between the current position of the spool and the current position of the valve spindle, so that the adjustment operation of the exhaust valve depends only on the adjustment of the spool and the hydraulic pressure Unaffected by changes in the period or changes in the period during which the spool remains in a particular position. The spool places the spindle in an intermediate position and allows direct operation of the spindle while the spindle is between the limit positions. As the spindle further moves substantially simultaneously with the spool, the exhaust valve can move as desired during the engine cycle, independent of the current rotational speed of the engine.
[0006]
Preferably, the end point of the closing operation of the exhaust valve is actively controlled by the control valve instead of braking the spindle by the throttling action because the throttling action leads to energy loss. If the control valve controls the final part of the closing operation, and thus the braking action of the spindle, the amount of energy flowing from the high pressure hydraulic fluid to the exhaust valve actuator is reduced. By eliminating the need to associate precisely formed ports to form the throttle gap, the actuator design is simplified.
[0007]
Furthermore, it is possible to change the speed of the exhaust spindle in a predetermined part of the operating path from one engine cycle to the next. For example, the speed of the exhaust valve can be increased at the beginning of the opening operation, which accelerates the opening speed of the valve. As a result of the rapid acceleration and the spindle moving away from the closed position to the open position, the desired large outflow area is quickly realized, so the degree of heating of the valve disc and the fixed valve seat is reduced. The ability to vary the speed of the exhaust valve during engine operation allows the current operating conditions to be continuously adjusted.
[0008]
The method according to the present invention can stop the opening operation of the exhaust valve at an intermediate opening position before reaching the fully opened position, so that the position where the spindle is kept open is changed as desired. It offers a favorable possibility. This reduces the consumption of hydraulic fluid and the energy consumption of pressurizing the hydraulic fluid. When the engine is operating at partial load, the amount of exhaust gas is less than per engine cycle, the engine type can make the engine speed slower and more to exhaust the exhaust. Will provide time. Both of these situations allow for a reduced spill area.
[0009]
The possibility of precisely controlling the operation of the spindle can be used as appropriate, and the spindle can be held in the ventilation position for the waiting time during the final part of the closing operation. In this ventilation position, there is a ventilation gap between the valve seat surfaces of the exhaust valve, which moves the spindle to its fully closed position. By keeping the exhaust valve open for a period of time (referred to as standby time) near its fully closed position, relatively cool air will flow over the surface of the valve seat and the valve seat will be substantially cooled. . As a result, the average temperature of the valve material decreases, thus extending the life of the exhaust valve, which allows the use of other less expensive valve seat materials. The durability of the valve seat is further improved by being able to blow off all the particle residues with a strong flow of ventilation air, which reduces the occurrence of dent marks.
[0010]
The standby time can be appropriately set within a range of 4 ms to 50 ms. This range is suitable for low or medium speed engines with large bores. When the waiting time is 4 ms or less, the desired cooling becomes extremely poor, and when the waiting time is 50 ms or more, the amount of air consumed for cooling becomes excessively large.
[0011]
Preferably, the spindles in the ventilation position are held at a mutual distance in which the valve seats are in the range of 0.02 mm to 0.50 mm, and the sonic air flow through the ventilation gap, preferably 0.05 mm to 0.2 mm. This reduces the amount of air that flows out, so that the compressed air remains substantially unaffected.
[0012]
In the final part of the closing motion, the spindle is first moved to the substantially closed position, then immediately moved in the opening direction for a short time, and then moved to its fully closed position. The occurrence of marks) can be further reduced. In the first, almost completely closed state, all particles present between the valve seat surfaces are crushed into dusty material, and afterwards, when the spindle is opened for a short time, it becomes powerful. A flow of ventilation occurs, and the pulverized dust material is blown off with the exhaust gas. After that, when the valve is completely closed, no particles are present on the face of the valve seat and the formation of dent marks is prevented.
[0013]
In order to limit the amount of charge air discharged, a short movement in the opening direction and a movement to the fully closed position take place within a time shorter than one tenth of the time the exhaust valve opens. The combination of the cooling and cleaning effects on the valve seat surface can be limited in terms of time.
[0014]
The invention further relates to an exhaust valve, said exhaust valve comprising a valve spindle having a hydraulic actuator with a fixed cylinder with at least an actuator piston associated with the first pressure chamber, and said first pressure chamber. And a control valve that can be connected at least to a high pressure port or a low pressure port of the control valve housing.
[0015]
A control valve housing having a high pressure port and a low pressure port is longitudinally displaceable, the longitudinal displacement of the control valve housing being proportional to the longitudinal displacement between the open and closed positions of the exhaust valve spindle By setting the structure of the exhaust valve as described above, more accurate control can be realized. When the spindle, and thus the housing, is in the desired position determined by the current position of the spool, the control valve can be hydraulically deactivated in a simple manner by displacing the housing with the spindle.
[0016]
Preferably, the control valve housing is not moved longitudinally with respect to the exhaust valve spindle so that the housing and the spindle are displaced proportionally in the same operation, i.e. in a ratio of 1: 1. I can do it. Alternatively, the displacement of the spindle is increased relative to the displacement of the control valve housing so that the displacement is proportionally performed at a predetermined ratio, for example 1: 2 or 1: 3. It is also possible for the control valve spool to have a relatively short stroke distance.
[0017]
In one particularly simple design, the actuator piston forms the control valve housing. In another simple design, the upper part of the valve spindle constitutes the control valve housing. By allowing the actuator to be directly controlled by the control valve spool itself without any intermediate connecting members, the exhaust valve is controlled directly and without a delay element. The minimal number of control components provides extremely high reliability.
[0018]
In one embodiment, the control valve spool is mounted so that it cannot move longitudinally on the moving magnet portion of the linear motor (its stationary coil component is mounted coaxially within the extended portion of the exhaust valve spindle). It is done. Since linear motors can be controlled based on electronic signals from the controller regardless of both the current position of the moving parts and their speed, it is not possible to use a linear motor to adjust the control valve spool. The design of the mechanical members is simplified to an advantageous degree. Alternatively, the spool can be driven by a camshaft cam, but this requires mechanical synchronization of the engine camshaft and crankshaft, and therefore during operation the engine The possibility of freely changing the exhaust valve operating pattern during the cycle is limited.
[0019]
When a linear motor is used, the moving parts of the linear motor preferably have a stroke distance that is longer than the maximum stroke distance of the exhaust valve between the closed position and the fully open position. This makes it possible to compensate for changes in the length of the exhaust valve due to wear, temperature changes, etc., and the characteristics of the linear motor can change in the region near the limit position, making it more accurate. It is also possible to control.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The drawings are described in more detail below with reference to the accompanying drawings, which are very schematic.
FIG. 1 shows the upper part of a cylinder 1 in an internal combustion engine which can be a two-stroke or four-stroke engine with a large cylinder bore, such as a bore of at least 200 mm, typically in the range of 240 mm to 1200 mm. Has been. The engine can be, for example, a supercharged, constant pressure, two stroke crosshead engine for ship propulsion or stationary power generation equipment. An exhaust valve 2 is attached to the uppermost part of the cylinder in the cylinder cover 3. This cylinder is scavenged by uniflow scavenging. That is, the scavenging port is formed in the lower part of the cylinder. Further, the exhaust valve can be formed at a location other than the center of the cylinder cover, for example, on the side wall of the cylinder, or several exhaust valves can be attached to the same cover.
[0021]
The exhaust valve comprises a spindle 4 with a valve disc having an upper annular valve seat valve which can abut a fixed valve seat valve below the cover 3 in a sealing manner. When in the closed position, the exhaust valve disconnects the connection between the combustion chamber 5 and the exhaust passage 6 and when in the open position, the spindle 4 is displaced downward in the longitudinal direction.
[0022]
For example, a high pressure conduit 7 having a high pressure hydraulic fluid, such as in the range of 10 MPa (100 bar) to 50 MPa (500 bar), typically 15 MPa (150 bar) to 30 MPa (300 bar) is illustrated. In the embodiment, the high pressure port 8 of the control valve housing integrated with the spindle 4 is reached (see the example of FIG. 5). The low pressure conduit 10 connects the low pressure port 11 of the control valve housing to a drain pipe, i.e., a return pipe for spent hydraulic fluid. The drain port on the upper side of the cover 3 at the bottom of the outer valve housing 12 can be connected to the low pressure conduit 10 so that all leakage fluid can be removed. The low pressure conduit can be coaxially arranged around the high pressure conduit, which means that the length of the passage extending downward from the exhaust valve housing to the high pressure conduit extending parallel to the engine is a few meters long, This is particularly beneficial for large engines that can also supply hydraulic driving force to inject fuel along with hydraulic fluid. In addition to providing a larger space by arranging the low-pressure conduit and the high-pressure conduit coaxially, the low-pressure conduit also functions as a protective shield around the high-pressure conduit if the high-pressure conduit breaks.
[0023]
In the illustrated embodiment, the pneumatic spring piston 13 is fixed to the spindle 4 and is displaceable in the pneumatic spring cylinder 15 and the pneumatic spring chamber 14 is arranged below the piston. , Compressed air is supplied from the pneumatic conduit 15a. The pneumatic spring continuously acts on the spindle 4 with upward force toward the closed position.
[0024]
An electronic control device 16 connected to the relevant cylinder receives data from the signal device 17 regarding when the exhaust valve should be opened and when it should be closed. This data can be an actuation signal determined by another controller that can be centrally located throughout the engine, or the opening and closing times within the controller 16 based on signals received from another signal source 18. It can be data based on the current angular position of the crankshaft intended to be actuated. These data are data relating to the current load of the engine and, for example, one of several predetermined operating modes that require the exhaust valve to be operated in a particular way that deviates from the standard operating mode. The data can be information about the possibility of the engine operating in one mode.
[0025]
Through the signal line 19, the control device 16 generates the required setting signal for the exhaust valve while the spindle moves between the closed position and the open position, and through the line 20, the control device The position signal can be received from the sensor that measures the current position of the spindle by itself or in one member connected to the spool 21 in the control valve.
[0026]
The electromagnetic converter 22 converts an electrical signal from the control device into a linear displacement amount of the spool in the control valve. In an embodiment not shown, the control valve is arranged separately from the spindle 4, so that there is a relatively long connection path between the pressure chamber and the control valve port in the actuator described below. . However, this separation makes it possible to orient the longitudinal axis of the control valve in a direction (horizontal direction) other than the direction coaxial with the longitudinal axis of the spindle. Furthermore, because of this separation, the transducer 22 does not move in the same way as the spindle, but instead moves a short distance, the movement of which is the same size as the desired displacement of the spindle 4 in the amplifier. It can be set as the apparatus converted into a linear motion. For example, the displacement of the spool can be converted into a displacement amount four times that of the spindle in the amplifying device, i.e., the spool and spindle are proportionally displaced in the longitudinal direction at a ratio of 1: 4.
[0027]
By displacing the spindle 4 in the longitudinal direction in proportion to the amount of displacement of the spool, the control device 16 is able to place the spool and thus the spindle in a selected intermediate position so that the controller 16 can operate at any given point in its operation. The spindle can be braked or accelerated via the electromagnetic transducer 22. The selected position may be a predetermined intermediate position, or a plurality calculated regularly by the controller based on the current operating mode of the engine and / or based on measurements of the actual operating sequence of the exhaust valves. Position. Referring to FIG. 2, an example operation sequence is illustrated, where the graph shows the downward displacement of the spindle as a function of time t. At point a, the exhaust valve is completely closed and the longitudinal displacement of the control valve spool is just started, so that the actuator acts on the spindle with an opening force that initiates the spindle movement, which is Continue to point b, at which point the speed of the spool is slowed down sufficiently, so that the closing force of the pneumatic valve causes the spindle 4 to stop at the fully open position 1max at point c. Practically enough to carry on. Next, the spindle remains stopped until the closing operation starts at point d. This is because the transducer 22 begins to displace the spool back toward the start position. When the spindle approaches the closed position, the control device 16 brings the spindle to the stop position at a short distance e from the closed position so that there is a ventilation gap of, for example, 0.3 mm between the valves in the valve seat. The spool speed can be reduced until In this narrow gap, the air that flows out has a sound velocity that generates a powerful cooling effect, but since this gap is very narrow, the amount of air flow is very small. This cooling effect can be achieved without appreciably losing the compression pressure in the combustion chamber above the piston 23. The exhaust valve is completely closed at time f after the waiting time, which is freely adjustable by the controller with respect to empirical values for the correlation between the current operating mode and the need for cooling. Or can be adjusted based on a measurement of the actual temperature of the valve seat material, as measured appropriately by a temperature sensor located in the fixed valve seat.
[0028]
In certain operating conditions, if it is desired to exhaust the cylinder more quickly or to scavenge more strongly with scavenging air, the controller 16 may wait longer before decelerating the spindle 4. Instead, it decelerates more strongly from the point b ′ as shown by the broken line. In a corresponding manner, the dashed line indicates a closing action by temporarily changing the operating state, for example by moving the spool more rapidly towards the starting position until the valve is closed at the point f ′. It can be accelerated as desired.
[0029]
FIG. 3 shows a closing sequence in which the spindle is first brought to the closing position at a point f ″ for a short time and immediately reopens to the ventilation position marked at point e. As described above, all particles trapped between the valve seats closed thereby are crushed and blown away. The valve seat is not exposed to strong forces until the combustion pressure begins to act on the valve disc, so that the temporary closing of the valve creates a large impact force that creates dents. There is no addition to the material. After a suitable waiting time, the spindle 4 is displaced to the fully closed position indicated by the point f ′ ″.
[0030]
When the engine is operating at partial load, the gas volume that must be exhausted every revolution of the engine is insignificant. For this reason, the spindle need not move to the fully open position. As illustrated in FIG. 4, the spindle 16 is moved downward a small distance by the control device 16 decelerating the spool more quickly to the stop position, thereby reducing hydraulic fluid consumption. A shorter opening action can also be chosen if the controller receives an alarm signal for an abnormally small amount of hydraulic fluid in the conduit 7.
[0031]
In the following description of other embodiments of the present invention, the same reference numerals as those described above apply to features that serve the same function.
FIG. 5 illustrates the top of the spindle 4 integral with both the piston portion of the actuator and the control valve. The left half of the drawing shows the control valve and actuator in the starting position, the position where the exhaust valve is closed, and the right half shows the open position. The spindle 4 advances upward into the lower portion 25 of the central bore of the actuator housing 24 in a pressure-sealed state. The actuator housing holds an end cover 26 at the top and has a tubular shield 27 below the transducer 22 mounted coaxially with the spindle 4. The converter shown in the figure is, for example, a model P01-23 × 160 with a maximum stroke of 140 mm or less by a linear motor type LinMot (trade name) produced by Sulzer Electronics AG of Switzerland. Can do. This transducer comprises a stationary coil part and a displaceable, movable magnet part 31 in the form of a magnet on a rod, with a spool in the control valve at the part 31 at the lower end of the rod. On the other hand, it is arranged so that it cannot be displaced in the longitudinal direction.
[0032]
Within the actuator housing, a lower end 28 is fixed to the first pressure chamber 29, and the annular wall 30 at the top of the spindle 4 is located on the shield 27 between the cylindrical inner surface 37 and the cylindrical outer surface at the lower end. And protrude upwards in a pressure-sealed state. The actuator piston includes a first piston portion 32 having an upper first opening region 33 defined by an inner diameter and an outer diameter of an annular piston portion, and a second piston portion having an upper opening region 35. 34. In the starting position, where the first piston part abuts the annular upper surface of the second piston part, the total opening area corresponds to the area of the annular part. This annular portion is defined by the outer surface of the piston portion 32 that slides along the inner surface of the chamber in a pressure-sealed state and the outer surface of the wall 30 that slides in a pressure-sealed state along the cylindrical inner surface 37 at the lower end. Made.
[0033]
While the actuator piston moves downward, the first piston portion 32 sits on the shoulder 38 on the inner surface of the actuator cylinder and stops, so that only the second piston portion continues to move. During the remainder of the opening operation, the open area is up to the area of the annular portion defined by the outer surface of the piston portion 34 sliding in a pressure-sealed manner along the inner surface 36 of the cylinder and the outer surface of the wall 30. to shrink.
[0034]
The actuator piston has a closed area 39 corresponding to the area of the annular part. This annular portion is defined by the outer surface of the spindle 4 sliding in a pressure sealed manner along the lower portion 25 of the actuator housing and the outer surface of the piston portion 34 sliding along the inner surface 36. The closed area is located in the second pressure chamber 40.
[0035]
The high pressure conduit 7 is connected to the actuator housing at the second pressure chamber 40, and the passage 41 reaches the high pressure port 8. The low pressure conduit 10 is connected to the cavity of the actuator housing above the lower end 28 and the passage 42 connects the low pressure port 11 to the cavity. The control valve spool 21 has a smaller-diameter intermediate portion and two cylindrical end portions that abut against the inner surface of the cylindrical hole of the control valve housing 45 in a pressure-sealed state. In the illustrated embodiment, it is formed directly on the upper part of the spindle 4. Via a short passage 43 the control port is in continuous communication with the first pressure chamber. In the neutral position of the control spool, the two end portions of the spool only block the high and low pressure ports. When the spool 21 is displaced downward with respect to the actuator piston, the high pressure port is exposed, so that fluid flows into the first pressure chamber, which causes the actuator piston to be spindled until the high pressure port is closed again. 4 is displaced together. When the spool 21 is displaced upwards relative to the actuator piston, the low pressure port is exposed, so that fluid flows out of the first pressure chamber, thereby the actuator piston until the low pressure port is closed again. Is moved upward together with the spindle 4. Thus, the actuator piston is controlled so as to accurately follow the displacement operation of the spool 21.
[0036]
Due to such control, the closing and opening areas of the actuator piston can be made relatively large, providing an extra force for adjusting the spindle 4 and thereby ensuring a quick and accurate adjusting action. It will be. If surplus force is allowed, the dimensions of the piston area can be calculated based on the adjustable minimum pressure in the high pressure conduit 7, so that the surplus force remains even if the pressure in the conduit changes. It only increases.
[0037]
As the actuator performs an adjustment action, fluid flows through the actuator to cool the actuator. In the embodiment shown in FIG. 5 in which the control valve is integrated with the actuator piston, the length of the passage 43 from the control port to the chamber 29 is minimal, so that the adjustment of the spool and the operation of the actuator piston The control connection in between is advantageous in that it is direct and inelastic, with minimal power loss.
[0038]
The drain passage 44 can be kept free of leaking fluid in the space below the first piston portion 32. The embodiment of FIG. 5 need not be used with a pneumatic spring in the spindle 4. If a pneumatic spring is used, the first closing area 39 can be omitted, otherwise it must be taken into account that the air spring has a closing force when setting the dimensions of this area. .
[0039]
The above method of keeping the exhaust valve in the final stage, cooling the ventilation position, crushing and blowing all particles can also be used with other actuators, such as cam-controlled actuators, The form is particularly suitable for using this method because of its functional accuracy.
[0040]
The embodiment shown in FIG. 5 can be modified. The actuator piston can be manufactured and separated, for example, separately from the spindle 4, and a stop penetrating a bolted joint, a threaded joint or both parts is inserted into the transverse hole or in the axial direction. It can be placed in the extension by other mechanical fastening means. In the actuator piston itself, the control valve housing can be further formed as a separate member that is inserted and secured in the bore of the actuator piston. For example, such a fixation can be effected by a hole in a piston having a conical housing outer surface and a corresponding conical surface pressed against the housing, or these parts can be shrink fit or screwed together. .
[Brief description of the drawings]
FIG. 1 is an illustration of an exhaust valve according to the present invention.
FIG. 2 is a diagram illustrating an example of an operation sequence performed by the exhaust valve of FIG.
FIG. 3 is a diagram illustrating an example of an operation sequence performed by the exhaust valve of FIG. 1;
4 is a diagram showing an example of an operation sequence performed by the exhaust valve of FIG. 1. FIG.
FIG. 5 is a more detailed view of a portion of the illustrated embodiment.
[Explanation of symbols]
1 Cylinder 2 Exhaust valve
3 Cylinder cover 4 Spindle
5 Combustion chamber / Pneumatic spring cylinder
6 Exhaust passage 7 High pressure conduit
8 High pressure port 10 Low pressure conduit
11 Low pressure port 12 Outer housing
13 Pneumatic spring piston 14 Pneumatic spring chamber
15 Pneumatic conduit 16 Electronic control unit
17 Signaling device 18 Signal generation source
19 signal lines 20 lines
21 Control valve spool 22 Electromagnetic transducer
23 Piston 24 Actuator housing
25 Lower part of actuator housing
26 End cover 27 Tubular shield
28 Lower end of actuator housing
29 first pressure chamber 30 annular wall
31 Magnet part 32 First piston part
33 First opening region 34 Second piston portion
35 Opening area 36 Cylinder inner surface
37 Cylindrical inner surface 38 Shoulder
39 First closed region 40 Second pressure chamber
41, 42 passage 43 short passage
44 Drain passage 45 Control valve housing

Claims (12)

The exhaust valve is opened by the spool (21) of the control valve which is displaced longitudinally so that the high pressure port (8) can be connected to the first pressure chamber (29) in the actuator, and the actuator pistons (32, 34). Is displaced along with the exhaust valve spindle (4) towards the open position of the exhaust valve, and when the exhaust valve is to be closed, the low pressure port (11) is controlled to connect with the first pressure chamber (29). In the method of operating the exhaust valve (2) for an internal combustion engine, in which the valve spool (21) is displaced in the longitudinal direction, the spindle (4) of the exhaust valve is proportional to the longitudinal displacement of the control valve spool (21). are displaced longitudinally by the spindle is disposed in a selected position between the fully open position and fully closed position, said actuator piston (32, 34), the exhaust valve Operation wherein the move is that to follow the displacement operation of the control valve spool (21) when the Flip is moved between a position and an open position. 2. The method according to claim 1, wherein when the exhaust valve spindle (4) approaches the closed position, the speed of the control valve spool (21) decreases in order to brake the closing action of the spindle (4). A method characterized by being squeezed . 3. The method according to claim 1 or 2, wherein the opening action of the spindle (4) of the exhaust valve is such that the spindle (4) is less than the distance (lmax) between the closed position and the open position. And stopping at an intermediate open position displaced away from the head . 4. The method according to claim 2 or 3, wherein in the final stage of the closing operation, the distance between the seat surfaces of the exhaust valve is in the range of 0.02 mm to 0.5 mm and there is a ventilation gap between these seat surfaces. The speed of the control valve spool (21) is reduced so that the exhaust valve spindle (4) is in the ventilation position where the spindle (4) is in the ventilation position for a waiting time in the range of 4 ms to 50 ms. A method characterized by being moved to a fully closed position after being held. 5. The method according to claim 4, wherein the distance between the seating surfaces of the exhaust valve in the ventilation position is in the range of 0.05 mm to 0.2 mm. 6. The method according to claim 4 or 5, wherein in the final stage of the closing operation of the exhaust valve, the spindle (4) is first brought to a substantially closed position in order to break up particles present between the seating surfaces of the valve. Moved and then immediately moved in the opening direction for a short time to blow away the crushed particles by the outflowing air and then moved to its fully closed position. 7. A method according to claim 6, characterized in that the short time movement in the opening direction and the movement to the fully closed position occur within a time shorter than one tenth of the time for the exhaust valve to open. . An internal combustion engine comprising a valve spindle (4) with a hydraulic actuator having a static cylinder with at least a first pressure chamber (29) and an associated actuator piston (32, 34) and a control valve. An exhaust valve for
The control valve is
A control valve housing with a high pressure port (8) and a low pressure port (11);
When the actuator piston (32, 34) is moved in the opening direction of the valve spindle (4), the high pressure port (8) is connected to the first pressure chamber (29), and the actuator piston (32, 34) 34) displaceable longitudinally in the control valve housing to connect the low pressure port (11) with the first pressure chamber (29) when moved in the closing direction of the valve spindle (4) A control valve spool (21),
The control valve housing is movable in the longitudinal direction, the longitudinal displacement of the control valve housing being proportional to the longitudinal displacement between the open and closed positions of the exhaust valve spindle (4). An exhaust valve characterized by having   The exhaust valve according to claim 8, wherein the control valve housing (45) comprises: An exhaust valve which does not move in a longitudinal direction with respect to the exhaust valve spindle.   9. Exhaust valve according to claim 8, characterized in that the upper part of the actuator piston or valve spindle forms the control valve housing (45).   11. Exhaust valve according to any one of claims 8 to 10, wherein the control spool (21) is a movable linear motor whose stationary coil part is coaxially mounted in the extension of the exhaust valve spindle (4). The exhaust valve is mounted so as not to move in the longitudinal direction on the magnet part (31).   12. Exhaust valve according to claim 11, characterized in that the movable magnet part (31) of the linear motor has a stroke distance longer than the maximum stroke distance of the exhaust valve between the closed position and the fully open position. valve.

Images