EP2143894B1 - Combustion engine with a motor brake device and a valve lash adjusting mechanism - Google Patents

Description

The invention relates to an internal combustion engine having at least one combustion chamber, from which by means of at least one exhaust valve exhaust is discharged, comprising an engine brake device with a hydraulic auxiliary valve control unit, which is integrated into the exhaust valve with a camshaft connecting link mechanism and the exhaust valve when the engine brake device in an intermediately opened position.

Such internal combustion engines are for example in the EP 0 736 672 B1 and EP 1 526 257 A2 described. The engine braking devices of these internal combustion engines are each a hybrid form of an engine dust brake and a decompression brake, which is also referred to in particular as EVB (= exhaust valve brake). The hydraulic valve Zusatzsteuereiriheit is in the variant according to the EP 0 736 672 B1 in a rocker arm of the link mechanism and in the variant according to the EP 1 526 257 A2 mounted on one side in a two outlet valves simultaneously actuated valve bridge of the connection mechanism. The supply of the hydraulic additional valve control unit with oil by means of the already existing oil circuit of the respective internal combustion engine. In both variants, separate adjusting screws are provided to compensate for the play of the exhaust valve, based on which the valve clearance adjustment is made during engine mounting and then at regular service intervals. This is expensive. If the valve clearance is accidentally set too low by the installation or service personnel, the outlet valve will rattle and there is a risk of damage to the valve train. If the valve clearance is accidentally set too high, the exhaust valve will not open sufficiently, so that complete gas exchange is not guaranteed.

From the US 6,394,067 B1 an engine brake device is known with a hydraulic auxiliary valve control unit, which is integrated in a connecting the exhaust valve with a camshaft connecting mechanism, which holds the Aulassventil with the engine brake device in an intermediate open position. Further, a hydraulic valve clearance compensation mechanism for the exhaust valve is described, which is connected to the oil supply to a main oil circuit, whereas on the other hand, the hydraulic valve addition control unit is connected to the oil supply to an additional oil circuit provided in addition to the main oil circuit.

The object of the invention is therefore to provide an internal combustion engine of the type described, which enables safe and reliable operation with the least possible installation and service effort.

To solve this problem, an internal combustion engine according to the features of claim 1 is given. The internal combustion engine according to the present invention also includes a hydraulic valve clearance compensating mechanism for the exhaust valve, wherein the hydraulic valve clearance compensating mechanism for oil supply is connected to a main oil circuit, and the hydraulic valve auxiliary control unit for oil supply is connected to an auxiliary oil circuit provided in addition to the main oil circuit.

The internal combustion engine according to the invention thus has both the valve auxiliary control unit, which is favorable for the engine braking force effect, and a compensating mechanism which carries out the valve clearance adjustment, in particular automatically. A time-consuming and costly and error-prone regular adjustment by hand is unnecessary. The inventive Internal combustion engine thus offers an additional functionality compared to previous engine equipped with an engine braking device, which makes the operation safer and more efficient.

The parallel operation of the additional valve control unit and the valve clearance compensation mechanism, both of which function hydraulically, is made possible in particular by the mutual decoupling of the oil feed. The valve clearance compensation mechanism covers its oil requirement via the main oil circuit, which in any case is present anyway in the internal combustion engine, in which a substantially constant oil pressure prevails during operation. In contrast, a separate additional oil circuit is provided for the operation of the additional valve control unit and thus the engine braking device, which works in particular largely largely independent of the main oil circuit. Alternatively, the main oil circuit and the additional oil circuit may also be connected to a central oil pump for pressure generation.

The additional oil circuit, in particular its oil pressure, can be readily and separately adapted to the mode of operation and the operating state of the engine braking device without further ado and especially without interfering with the areas and components of the internal combustion engine fed by the main oil circuit. Thus, for example, an activation and deactivation of the engine brake device is possible by the additional valve control unit accordingly by means of the additional oil circuit, preferably centrally on or off. The additional valve control unit of the engine brake device is preferably activated only when this is actually desired, that is, when the engine brake has been actuated by the driver. During normally-fired engine operation, on the other hand, the auxiliary valve control unit of the engine brake device is deactivated a undesirable in this operating situation braking effect is reliably prevented. This also provides safer and more efficient operation compared to the prior art both during an engine braking phase and during a normal engine operating phase.

Advantageous embodiments of the internal combustion engine according to the invention emerge from the features of the claims dependent on claim 1.

Favorable is a variant in which an oil pressure of the additional oil circuit is preferably centrally controlled or regulated. Thus, both the use of the engine braking effect and its strength can be set very accurately and in particular also change depending on the operating situation. In addition, the additional valve control unit so particularly easy on or off. In order to influence the oil pressure or the oil pressure level, the additional oil circuit may be filled with suitable components, e.g. Pressure reducing valves or booster means in the form of an additional oil pump, be equipped.

Furthermore, the additional oil circuit can be connected to the additional valve control unit, in particular by means of a counter-holder, for example designed as a stop and in particular already existing anyway. This is very space saving. For the supply of the additional valve control unit with the oil of the additional oil circuit then at least in the area close to the valve practically no additional space is required.

According to another preferred variant, the anvil comprises an oil feed channel with a check valve, which in particular during an engine braking phase then undesirable oil reflux into the additional oil circuit prevents and blocks the auxiliary valve control unit, so that the exhaust valve is held in a slightly open (= intermediate) position. The integration of the check valve in the anvil is space-saving.

Preferably, the counter-holder also has as a stop element a first piston of a counter-holder integrated in the first hydraulic piston-cylinder unit. This automatically compensates for any play between the anvil and the adjoining part of the connection mechanism. The clearance compensation is required because, due to the valve clearance compensation mechanism, the position of the counterpart abutting part of the connection mechanism is undefined. The first hydraulic piston-cylinder unit also preferably includes a return spring, which causes a reset of the first piston in normal-fired engine operation, in which in particular a low oil pressure is set in the additional oil circuit. Upon return of the first piston, the displaced oil can drain through, in particular, a through hole of the counter-holder which belongs to the additional oil circuit.

According to a further preferred embodiment, the additional valve control unit is designed as a non-return valve-free second hydraulic piston-cylinder unit with a second piston and in particular with an adjusting spring.

Also favorable is a variant in which the additional valve control unit is connected by means of a third hydraulic piston-cylinder unit to the valve play compensation mechanism. This third hydraulic piston-cylinder unit advantageously couples the auxiliary valve control unit and the valve lash adjuster mechanism with each other. The third hydraulic piston-cylinder unit fulfills several functions. So it serves as a switching element between the engine braking operation and the normally fired engine operation. In addition, it absorbs oil displaced from the first hydraulic piston-cylinder unit in balancing the play between the anvil and the adjoining part of the link mechanism. In this respect, it is provided according to a further advantageous embodiment that a front oil receiving chamber of the third hydraulic piston-cylinder unit has a receiving volume which is at least as large as that of an oil pressure chamber of the first hydraulic piston-cylinder unit.

According to a further advantageous embodiment, a third piston of the third hydraulic piston-cylinder unit in a side wall on a first discharge opening. At a certain position of the third piston, this first exhaust port releases an oil passage connected to the valve lash adjuster mechanism so that oil can flow out of the lash adjuster mechanism and / or out of the auxiliary valve control unit.

It is furthermore preferred if the valve play compensation mechanism is designed as a fourth hydraulic piston-cylinder unit with a fourth piston, which has a second discharge opening in a side wall. At a certain position of the fourth piston, this second discharge opening releases an oil passage connected to the additional valve control unit so that oil from the auxiliary valve control unit can flow into the oil receiving space of the fourth hydraulic piston-cylinder unit and drain therefrom.

Further features, advantages and details of the invention will become apparent from the following description of an embodiment with reference to the drawing. The single figure shows a partial cross-sectional view of an embodiment of an internal combustion engine 1 with an engine brake device 2 and with an automatic compensation mechanism for both the valve clearance and the stop play of the engine brake device. 2

The internal combustion engine 1 has a plurality of cylinders, not shown in the figure, each receiving a combustion chamber. Each of these combustion chambers can be supplied with air or an air-fuel mixture by means of at least one inlet valve. In addition, in the illustrated embodiment, each combustion chamber has two exhaust valves 3 and 4, by means of which exhaust gas can be discharged into an exhaust duct. The exhaust valves 3 and 4 are mechanically controlled and actuated by means of a common valve bridge 5. The valve bridge 5 is part of a connecting mechanism which connects the exhaust valves 3 and 4 with a camshaft of the internal combustion engine 1 not shown in the figure. The connecting mechanism also includes a likewise not shown in the figure rotatably mounted rocker arm. The rocker arm acts via a contact pin 6 partially shown on the valve bridge 5. For this purpose, the contact pin 6 is provided at its free end with a ball joint articulated Stützkalotte 7.

In the interior of the contact pin 6 and the Stützkalotte 7 runs an oil supply passage 8 of a particular lubrication, but also for hydraulic control provided main oil circuit of the internal combustion engine 1. The guided in this oil supply channel 8 oil has substantially always the same constant oil pressure P _constant during operation.

In addition, the internal combustion engine 1 has an additional oil circuit, which is designed substantially independently of the main oil circuit. The additional oil circuit is guided by means of an oil supply channel 9 in a counter-holder 10. The counter-holder 10 comprises a first piston-cylinder unit 11 with a round stop piston 12 and with a return spring 13, the spring force of the stop piston 12 in its retracted position, i. pushes back in the direction of the oil supply channel 9. In the extended position of the stop piston 12 shown in the figure, an oil pressure chamber 15 is formed between its rear boundary surface 14 and the oil supply passage 9. A check valve 16 (= return check valve) with a ball and a ball seat separates the oil pressure chamber 15 from the oil supply passage 9. The otherwise solid and formed with a double stepped outer contour stop piston 12 has a central through hole 17, which extends continuously from the rear boundary surface 14 to a front boundary surface 18 extends and which serves as an oil passage. The front boundary surface 18 forms a variable in position stop for the valve bridge. 5

The engine brake device 2 of the internal combustion engine 1 is of the EVB type. It includes, in addition to a throttle element not shown in detail in the exhaust duct and a central control unit also not shown in detail also for each cylinder, a hydraulic additional valve control unit 19, which is installed as a second piston-cylinder unit in the valve bridge 5. The second exhaust valve 4 is not provided in the embodiment shown, however, with such a control unit. Only the exhaust valve 3 contributes to the operation of the engine brake device 2.

The exhaust valves 3 and 4 are axially movably mounted with a shaft 20 and 21 in the cylinder head and acted upon by a closing spring 22 and 23 with a certain biasing force in the closing direction. The closing force of the closing spring 22 is designated F _Fed .

The exhaust valve 3 associated with the engine brake device 2 includes, as already above stirred, the hydraulic additional valve control unit 19, the circular control piston 24 is guided axially movably in a provided in the valve bridge 5 cylinder bore 25. The longitudinal cross-section H-shaped control piston 24 is supported at the upper end of the shaft 20 of the exhaust valve 3. The particular check valve-free additional valve control unit 19 also includes an adjusting spring 26 which is disposed on a side remote from the shaft 20 side of the control piston 24 in a control pressure chamber 27 and the control piston 24 presses against the shaft 20. The designated with F _NFed spring force of the adjusting spring 26 thus acts against the closing force F _{Fed of} the closing spring 22nd

In the control pressure chamber 27 opens at an end remote from the control piston 24 side, an oil passage 28, by means of which oil in the control pressure chamber 27 reach and can escape from the control pressure chamber 27 again. The oil passage 28 extends from the control pressure chamber 27 to a region of a surface of the valve bridge 5, which rests against the front boundary surface 18 of the stop piston 12 during a part of a brake cycle period when the engine brake device 2 is actuated. This operating situation with the stopper piston 12 abutting valve bridge 5 is shown in the figure.

At the front boundary surface 18, the through hole 17 of the stopper piston 12 opens into an outlet opening, which is arranged concentrically with an outlet opening of the oil passage 28 when abutting the valve bridge 5 stopper piston 12. In this constellation, oil of the additional oil circuit via the oil supply channel 9, the oil pressure chamber 15, the through hole 17, the oil passage 28 in the control pressure chamber 27 of the hydraulic auxiliary valve control unit 19 reach. The additional valve control unit 19 is thus temporarily connected to the auxiliary oil circuit by means of the first piston-cylinder unit 11 installed in the counter-holder 10. As long as the front boundary surface 18 of the stop piston 12 rests against the valve bridge 5, there is a hydraulic connection between the additional oil circuit and the additional valve control unit 19th

An oil pressure _control p and an oil pressure level of the auxiliary oil circuit can be changed by non-illustrated oil pressure variation means. This may be, for example, a pressure reducing valve or an oil pump. In this way it is possible to finely adjust the oil pressure p _control within the auxiliary oil circuit, which is secured through control or regulation. This task is in turn perceived by the central control / regulating unit of the engine brake device 2 which is not shown in the figure. Depending on the setting in the auxiliary oil circuit oil pressure p, the hydraulic _control valve auxiliary unit is switched on or off, or 19 controlled in more detail explained in the following effect on the displacement position of the exhaust valve 3 or regulated. Thus, the braking force of the engine brake device 2 can be adjusted very fine.

The additional valve control unit 19, in particular its control pressure chamber 27, is hydraulically connected to a circular and a longitudinal cross-section U-shaped Piston 29, a return spring 30 and a front and a rear oil receiving chamber 31 and 32 having third piston-cylinder unit 33 and a round and in longitudinal cross-section also U-shaped piston 34, an adjusting spring 35, a Ölaufnahaum 36 having fourth piston Cylinder unit 37 connected. For this purpose, an oil passage 38 is provided, which connects the control pressure chamber 27, the front oil receiving chamber 31 and - at a certain position of the piston 34 - the oil receiving chamber 36 with each other. The oil passage 38 is formed by a first within the valve bridge 5 transversely, that is perpendicular to the longitudinal axes of the shafts 20 and 21, extending transverse bore. This transverse bore is provided with a closure 39.

The third piston-cylinder unit 33 is a switching element whose piston positions are different depending on whether the user of the internal combustion engine 1 specifies the normally-fired engine operation or the engine brake operation. In addition, its front oil receiving chamber 31 serves to receive the oil located in the oil pressure chamber 15 when this oil is displaced during a backward movement of the stop piston 12. The maximum intake volume of the front oil receiving chamber 31 is therefore at least as large as that of the oil pressure chamber 15. Furthermore, the third piston-cylinder unit 33 also serves for oil drainage. Its rear oil receiving space 32 is therefore provided with an oil outlet opening 40. In addition, a side wall of the piston 29 has a discharge opening 41. At a certain position of the piston 29, namely exactly the position shown in the figure, this Absteueröffnung 41 connects the rear oil receiving chamber 32 with another transverse within the valve bridge 5 extending oil passage 42. The latter is in turn designed as a transverse bore, by means of another closure 43rd is sealed against an oil outlet.

The fourth piston-cylinder unit 37 forms a hydraulic valve clearance compensation mechanism that automatically compensates the play of the exhaust valves 3 and 4. The fourth piston-cylinder unit 37 is connected to the main oil circuit. For this purpose, with the support cap 7 of the contact pin 6 due to the spring force of the adjusting spring 35 in permanent contact standing piston 34 has in its piston crown a central oil supply passage 44 which is arranged concentrically to the oil supply passage 8 of the contact pin 6. At a the oil receiving space 36 facing the end of the oil supply channel 44, a check valve 45 (= return check valve) is provided, the ball is pressed in the embodiment shown by means of an additional check valve spring in the ball seat. The oil receiving chamber 36 is connected to the oil passage 42 at a side remote from the piston 34 for oil discharge. In addition, a side wall of the piston 34 has a discharge opening 46 which connects the oil receiving chamber 36 with the oil passage 38 at a certain position of the piston 34.

In the following, the modes of operation and special advantages of the engine brake device 2 and the valve play compensation mechanism will be described in more detail.

First, the engine braking operation will be explained. Upon actuation of the engine brake device 2, the throttle element is brought into throttle position in the exhaust passage, whereby exhaust gas accumulates in the exhaust passage between the exhaust valve opening of the cylinder and the throttle element. This back pressure in the exhaust duct can cause an intermediate opening of the exhaust valve 3, which occurs in particular at the end of the first engine cycle (= intake stroke) of each four-stroke cycle of the internal combustion engine 1. by virtue of the pressure conditions prevailing in the combustion chamber of the cylinder and in the exhaust duct results in a pneumatic force F _pn , which counteracts the closing force F _{Fed of} the closing spring 22 and under certain circumstances causes the mentioned intermediate opening of the outlet valve 3.

During the intake stroke, the rocker arm of the exhaust valves 3 and 4 is located on the cam base circle of the camshaft. As a result, the piston 34 of the fourth piston-cylinder unit 37 is at its top dead center. The Absteueröffnung 46 is closed. This operating situation is shown in the figure.

If one applied due to the operation of the engine brake all cylinders of the engine cylinder block of the engine 1 centrally with the oil of the auxiliary oil circuit by a correspondingly high oil pressure p _control is set, the stop piston 12 is pressed each of the first piston-cylinder unit 11 to the associated valve bridge 5 , The control pressure chamber 27 of the additional valve control unit 19 (= second piston-cylinder unit) also fills with the oil of the additional oil circuit as the front oil receiving chamber 31 of the third piston-cylinder unit 33. Their piston 29 therefore moves into its bottom dead center, whereby the discharge opening 41 is opened. This operating situation is shown in the figure

In this operating state caused due to the pressure conditions in the exhaust duct pneumatic force F _{pn is supported} by a hydraulic force F _Hyd , which _adjusts due to the application of the control pressure chamber 27 with the oil of the additional oil circuit. In addition, the spring force F _NFed the adjusting spring 26 supports the _{intermediate opening} . Is the sum of the spring force F _NFed , the pneumatic force F _pn and the hydraulic force F _Hyd greater than the closing force F _{Fed of} the closing spring 22, the intermediate _{opening of} the exhaust valve 3 takes place.

The strength of the hydraulic force F _Hyd can thus be used to regulate this process. Depending on the set in the additional oil circuit oil pressure p _tax , the exhaust valve 3 opens more or less wide or - at very low oil pressure p _tax in the additional oil circuit - not at all.

With an intermediate opening of the outlet valve 3, the control piston 24 follows the opening movement of the outlet valve 3 due to the spring force of the adjusting spring 26, whereby at the same time the volume of the control pressure chamber 27 increases. It flows oil from the additional oil circuit in the control pressure chamber 27, whereby the force of the adjusting spring 26 is supported. Since the oil due to the check valve 16 does not flow from the control pressure chamber 27 back into the oil supply passage 9 of the additional oil circuit and due to the closed Absteueröffnung 46 of the fourth piston-cylinder unit 37 can not flow elsewhere, the control piston 24 against the closing force F _Fed Closing spring 22 in position and thus also the mechanically coupled to the control piston 24 outlet valve 3 held in the intermediate open position. The control piston 24 is thus hydraulically blocked in the valve bridge 5, when the exhaust valve 3 after the beginning of the second clock made intermediate opening in the further course of the second and third clock tends to close again. The exhaust valve 3 thus remains during the second stroke (= compression stroke) and the following third stroke (= expansion stroke) in the intermediate open position, whereby the desired engine braking effect sets.

At the end of the third stroke, when the rocker arm reloads the valve bridge 5 due to the camshaft control to bring the exhaust valve 3 into the fully open position provided during the fourth stroke, the piston 34 of the fourth piston-cylinder unit 37 becomes downward of its bottom dead center, so that the Absteueröffnung 46 opens. Then located in the control pressure chamber 27 oil via the oil passage 38, the Absteueröffnung 46, the Ölaufnahaum 36, the oil passage 42, the already open Absteueröffnung 41 of the third piston-cylinder unit 33, the rear Ölaufnahteraum 32 and the oil outlet opening 40 drain. At the same time, the valve bridge 5 moves due to the load of the rocker arm of the stop piston 12 away, so that the contact tears off and the oil passage 28 opens. The oil located in the control pressure chamber 27 can therefore also flow out through the oil passage 28 into the region of the cylinder cover. Thus, the hydraulic lock of the control piston 24 is released. The oil drain from the control pressure chamber 27 is also assisted by the fact that the control piston 24 is pushed back in the direction of its retracted basic position (= top dead center) when the exhaust valve 3 closes again.

When Kipphebel return stroke also the stop piston 12 is pushed back into its top dead center after the renewed contact closure between the valve bridge 5 and the stopper piston 12. The oil previously held in the oil pressure space 15 can be received in the front oil receiving space 31 of the third piston-cylinder unit 33. The receiving volume of the front oil receiving chamber 31 of the third piston-cylinder unit 33 must be sufficiently large to accommodate the effluent from the oil pressure chamber 15 oil, so that the effluent from the oil pressure chamber 15 oil does not accumulate and to a undesirable movement of the control piston 24 leads. However, the receiving volume of the front oil receiving chamber 31 may not exceed a maximum receiving volume, so that the piston 29 of the third piston-cylinder unit 33 arrives safely in its bottom dead center. Otherwise, in a subsequent movement of the control piston 24 for the intermediate opening of the exhaust valve 3, the control pressure chamber 27 elastic because of the still possible residual stroke of the piston 29, whereby the exhaust valve can not be maintained in the intermediate open position. At the end of the fourth stroke (= Ausschubtakt) the valve bridge 5 is in any case back to the stop piston 12 and the rocker arm has reached the cam base circle again. A new brake cycle can begin.

The stop piston 12 is advantageously (hydraulically) trackable, so that a stop play between the anvil 10 and the valve bridge 5 is automatically compensated. This is also advantageous because the exact position of the valve bridge 5 is not exactly defined due to the valve clearance compensation effected by the fourth piston-cylinder unit 37. Due to the automatic tracking of the stop piston 12 whose position of the respective current position of the valve bridge 5 is adjusted so that no gap between the anvil 10 and the valve bridge 5 remains and the supply of the additional valve control unit 19 is ensured with the oil of the additional oil circuit.

The piston 34 of the fourth piston-cylinder unit 37, which is intended primarily for the lash adjuster, fulfilled in the internal combustion engine 1 further functions. It is also a control for the (EVB) engine brake cycle and a flow-off element for the discarded oil.

Furthermore, the provided in the valve bridge 5 bore configuration is particularly favorable. In particular, it allows use of the oil for both the functional movement, e.g. to bring the exhaust valve 3 in the intermediate open position and to hold there, as well as for the hydraulic control of the various mechanically moving components. For example, it is particularly advantageous if the longitudinal axes of the shaft 20, the control piston 24, the control pressure chamber 27, the stop piston 12 and the oil pressure chamber 15 and the center axes of the oil passage 28 and the through hole 17 are aligned.

In the following, the normal-fired engine operation will be explained. In this case, the engine brake device 2 is deactivated or switched off. For this purpose, on the one hand, the throttle element in the exhaust passage in the open position and on the other hand, the oil pressure p _tax in the additional oil circuit - possibly even to zero - reduced. The stop piston 12, the control piston 24 and the piston 29 are then at the respective top dead center. The stop piston 12 is brought into this operating state without significant oil pressure p due to the _control force of the return spring 13 in its fully retracted position. In this state, the stop piston 12 never hits the valve bridge 5.

If the rocker arm on the cam base circle of the camshaft is also the piston 34 of the fourth piston-cylinder unit 37 at its top dead center. The discharge opening 41 is closed. This oil of the main oil circuit can flow through the oil supply channels 8 and 44 in the oil receiving chamber 36, from where it can no longer escape, as long as the discharge opening 41 remains closed. From the under constant oil pressure p _constant standing oil of the main oil circuit flows such a large amount in the oil receiving chamber 36 that the current valve clearance due the hydraulic and by the adjusting spring 35 conditional tracking of the piston 34 is balanced. This is also done automatically. This depends on only very small amounts of oil. Therefore, in the check valve 45, the ball is held in the ball seat by means of a separate spring.

The effect of the p by the oil pressure _control of the auxiliary oil circuit described above in connection with the engine braking mode effected hydraulic force F _Hyd to the intermediate opening of the exhaust valve 3 can be used with advantage both for the engine braking, as well as to ensure an undisturbed normal fired engine operation. Thus, in particular in connection with the measures initiated to reduce the exhaust gas emission, a high dynamic pressure may form in the exhaust gas duct even during normally-fired engine operation, so that the outlet valve 3 tends toward an intermediate opening. This is undesirable during normal running engine operation, and is suppressed when equipped with the engine braking device 2 internal combustion engine 1, characterized in that the oil pressure p _control in the auxiliary oil circuit during normal running engine operation is greatly reduced or even completely switched off. This also reduces the hydraulic force F _Hyd . It then provides no appreciable contribution against the closing force F _Fed . However, the spring force F _NFed and the pneumatic force F _pn alone are not sufficient to cause a blocked intermediate _{opening of} the exhaust valve 3. Due to the set low oil pressure p in the _control circuit, the auxiliary oil hydraulic valve additional control unit 19 is turned off during the normal engine operation fired or deactivated.

Because of the additional oil circuit with specifically adjustable oil pressure p _control so can be achieved both during engine braking operation a finely adjustable braking effect as safe suppress then unwanted engine braking effect even during the normally fired engine operation.

In the internal combustion engine 1 is omitted during engine mounting and during the subsequent operation any adjustment of the valve clearance and the stop game (= EVB game) between the anvil 10 and the valve bridge 5. The balance of both games is due to the particularly advantageous embodiment of the engine braking device 2 and the lash adjuster mechanism (= fourth piston-cylinder unit 37) automatically. In particular, an automatic compensation of the thermal expansion of the exhaust valves 3 and 4 takes place. Since no games have to be bridged, the theoretically predefined control times can be observed more accurately. This has a favorable effect on the exhaust emissions. In addition, the compensation of the valve clearance and the EVB game reduces the noise of the internal combustion engine 1. There are acoustic advantages.

In principle, the described compensation mechanisms can also be used in the intake valves. The components used in the internal combustion engine 1 are not special components. Thus, e.g. the valve bridge 5 are used in its basic design in other internal combustion engines that are not equipped with an engine braking device. The valve bridge then contains only the fourth piston-cylinder unit 37 with a piston 34 without a discharge opening 46. The other three piston-cylinder units 11, 19 and 33, however, are superfluous. They are eliminated.

Claims (10)

1. Internal combustion engine having at least one combustion chamber from which exhaust gas can be discharged via at least one outlet valve (3, 4), comprising

   a) an engine braking device (2) with a hydraulic valve auxiliary control unit (19) which is integrated into a connecting mechanism (5, 6, 7) which connects the outlet valve (3) to a camshaft, which valve auxiliary control unit holds the outlet valve (3) in an intermediate open position when the engine braking device (2) is actuated, and

   b) a hydraulic valve play compensation mechanism (37) for the outlet valve (3, 4),
   wherein

   c) the hydraulic valve play compensation mechanism (37) for the outlet valve (3, 4) is integrated into the same connecting mechanism (5, 6, 7) that connects the outlet valve (3) to a camshaft,

   d) the hydraulic valve play compensation mechanism (37) is connected, for the supply of oil, to a main oil circuit,

   e) the hydraulic valve auxiliary control unit (19) is connected, for the supply of oil, by way of a control pressure chamber (27) to an auxiliary oil circuit provided in addition to the main oil circuit,

   f) the control pressure chamber (27) is connected to a front oil receiving chamber (31) of a third piston-cylinder unit (33) which acts as a switchover element and the piston (29) of which separates the front oil receiving chamber from a rear oil receiving chamber (32),

   g) the control pressure chamber (27) is connected to an oil receiving chamber (36) of a fourth piston-cylinder unit (37) when the piston (34) thereof assumes a predefined position,

   h) the oil receiving chamber (36) of the fourth piston-cylinder unit (37) is connected to the rear oil receiving chamber (32) of the third piston-cylinder unit (33) when the piston (34) thereof assumes a predefined position,

   i) the rear oil receiving chamber (32) of the third piston-cylinder unit (33) has an oil outlet opening (40).
2. Internal combustion engine according to Claim 1, characterized in that an oil pressure (p_Steuer) of the auxiliary oil circuit can be controlled or regulated.
3. Internal combustion engine according to Claim 1, characterized in that the auxiliary oil circuit is connected by means of a counter bracket (10) to the valve auxiliary control unit (19).
4. Internal combustion engine according to Claim 3, characterized in that the counter bracket (10) comprises an oil feed duct (9, 17) with a check valve (16).
5. Internal combustion engine according to Claim 3, characterized in that the counter bracket (10) comprises, as a stop element, a first piston (12) of a first hydraulic piston-cylinder unit (11) integrated in the counter bracket (10).
6. Internal combustion engine according to Claim 1, characterized in that the valve auxiliary control unit (19) is in the form of a second hydraulic piston-cylinder unit which does not have a check valve and which has a piston (24).
7. Internal combustion engine according to Claim 1, characterized in that the valve auxiliary control unit (19) is connected by means of the third hydraulic piston-cylinder unit (33) to the valve play compensation mechanism (37).
8. Internal combustion engine according to Claims 5 and 7, characterized in that a front oil receiving chamber (31) of the third hydraulic piston-cylinder unit (33) has a receiving volume which is at least as large as that of an oil pressure chamber (15) of the first hydraulic piston-cylinder unit (11).
9. Internal combustion engine according to Claim 7, characterized in that the piston (29) of the third hydraulic piston-cylinder unit (33) has a first discharge opening (41) in a side wall.
10. Internal combustion engine according to Claim 1, characterized in that the valve play compensation mechanism is in the form of a fourth hydraulic piston-cylinder unit (37) with a piston (34) which has a second discharge opening (46) in a side wall.

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