KR20040019008A - Method for operating an electrohydraulic valve control system of an internal combustion engine, computer program and control and regulating device for operating an internal combustion engine - Google Patents

Abstract

The electrohydraulic valve control device 10 of the engine includes at least one actuator 24 acting on the gas exchange valve 38. The actuator is connected to the high pressure reservoir 16 such that the actuator 24 is operated from the first position to the second position and is processed through an operating chamber 30 that is separated from the low pressure return 56. A simple constant pressure maintenance or pressure drop in the high pressure reservoir 16 is provided by the operating chamber 30 being simultaneously connected through the high pressure reservoir 16 and the low pressure return 56.

Description

TECHNICAL FOR OPERATING AN ELECTROHYDRAULIC VALVE CONTROL SYSTEM OF AN INTERNAL COMBUSTION ENGINE, COMPUTER PROGRAM AND CONTROL AND REGULATING DEVICE FOR OPERATING AN INTERNAL COMBUSTION ENGINE }

Such methods are known in the market. The electrohydraulic valve control device of the engine enables control of the gas exchange valve regardless of the position of the crankshaft or camshaft. This makes it possible in particular to save fuel and improve the emission characteristics of the engine.

In the electrohydraulic valve control device known in the market, the shaft of the gas exchange valve is connected with a hydraulic actuator. The actuator includes two operating chambers on both sides of the piston cross section having different sizes. The small cross section is again operated by the continuous high pressure of the high pressure reservoir supplied by the hydraulic pump. Likewise the large cross section of the piston is optionally connected with a high pressure reservoir or a low pressure return. This results in a power result of opening or closing the gas exchange valve.

In known methods, the amount of hydraulic fluid flowing from the high pressure reservoir through the actuator to the low pressure return and used for the operation of the actuator can be strongly varied. Also, for example, when the hydraulic pump is directly operated by the engine so that there is a supply output according to the engine speed of the hydraulic pump, the amount of fluid supplied into the high pressure reservoir by the hydraulic pump may also be changed.

However, in order to obtain a relatively constant pressure contained at the operating point in the high pressure reservoir, there has been provided an overpressure or pressure regulating valve so that hydraulic fluid is withdrawn from the high pressure reservoir, for example when the pressure is exceeded. Control of the feed rate via hydraulic pumps is known. In addition, the dynamic peak pressure in the high pressure reservoir can be passively relieved, for example, through the large volume of the high pressure reservoir.

However, the mentioned method in which the pressure in the high pressure reservoir can be kept constant is relatively expensive and partly reacts inactive to the pressure change in the high pressure reservoir. The high pressure reservoir, which is largely configured for mitigating the maximum pressure, is a disadvantage because typically only a small space is used in the engine compartment of the vehicle, for example. The same disadvantage is seen with pressure regulating valves.

It is therefore an object of the present invention to improve the method of the type described above so that the pressure in the high pressure reservoir can simply be kept constant.

This object is solved in the method of the type described above, in which the operating chamber is simultaneously connected with the high pressure reservoir and the low pressure return, thereby carrying out a constant pressure retention or pressure drop in the high pressure reservoir.

The present invention relates to a method of operating an electro-hydraulic valve control apparatus of an engine comprising at least one actuator acting on a gas exchange valve and comprising at least one operating chamber, wherein the actuator is located in a second position from the first position. The low pressure return is connected to the high pressure reservoir and operated from the second position to the first position, and the actuator is disconnected from the high pressure reservoir.

Particularly preferred embodiments of the invention are described in detail below in connection with the drawings.

1 is a schematic diagram of an electrohydraulic valve control device of an engine.

FIG. 2 is a graph showing the pressure progression in the high pressure reservoir over time of FIG.

3 is a graph showing the pressure of the high pressure reservoir over the engine speed of FIG.

The method according to the invention makes it possible to connect directly from the high pressure reservoir to the low pressure return without using additional components such as, for example, pressure regulating valves. To this end, the operating chamber is simultaneously connected with the high pressure reservoir and the low pressure return of the electrohydraulic valve control device to make the operating state clear. In order to keep the pressure constant, if the need for the hydraulic fluid to be withdrawn from the high pressure reservoir is determined, for example via a sensor, this can be carried out in the low pressure return section simply via the operating chamber in accordance with the invention.

Since the conventionally used selector valve has a short reaction time and high dynamic switching characteristics, a short time change in pressure in the high pressure reservoir can be mitigated. The pressure regulating valve can thus be omitted on the one hand via the method according to the invention. Also, the high pressure reservoir can be made small. This saves the production cost of the electrohydraulic valve control device and requires less construction space for the electrohydraulic valve control device.

Preferred embodiments of the invention appear in the dependent claims.

The first embodiment shows that the actuator's operating chamber is simultaneously connected with the high pressure reservoir and the low pressure return for constant pressure retention or pressure drop in the high pressure reservoir, and the accessory gas exchange valve is immediately closed. This embodiment of the method according to the invention is provided, in particular, when the actuator operation and the opening of the gas exchange valve are carried out via a complete high pressure operation. Thus, there is typically a pressure less than the highest pressure of the high pressure reservoir within the actuator's operating chamber in the closed stop switching position of the gas exchange valve.

However, when the high pressure reservoir and the low pressure return part are connected through the operating chamber of the actuator, there is a pressure below the maximum pressure of the high pressure reservoir in the operating chamber of the actuator. Thus, the closed stop switching position of the gas exchange valve does not affect the simultaneous connection of the operating chamber and the high pressure reservoir and the low pressure return.

It is particularly desirable for the operating chamber of the actuator to be connected simultaneously with the high pressure reservoir and the low pressure return to maintain a constant pressure drop or pressure drop of the high pressure reservoir, and that the accessory gas exchange valve is not opened on the basis of the high in-cylinder pressure. Do. In this way, unwanted opening of the gas exchange valve is effectively prevented in the actuator "sensitively" to the pressure change in the operating chamber.

The actuation of the actuator, which is to be connected directly to the high pressure reservoir and / or from the second position to the first position, just before the actuating chamber of the actuator, which must move from the first position to the second position, is disconnected from the low pressure return. It is possible to connect with the low pressure return just before the seal is disconnected from the high pressure reservoir.

In this case, the intended operation of the actuator is necessarily used for withdrawing hydraulic fluid from the high pressure reservoir. This is made possible by changing the view point by connecting the operating chamber, the low pressure return and the high pressure reservoir. This overlaps the time the operating chamber is connected with the low pressure return and the high pressure reservoir. This allows constant pressure retention or pressure drop in the high pressure reservoir to be integrated in normal operation of the actuator.

In the embodiment of the method according to the invention, when the engine is operated at low engine speed, it is preferred that the operating chamber of the actuator is temporarily connected simultaneously with the high pressure reservoir and the low pressure return. It is contemplated in this embodiment that at low engine speeds generally less pressure in the high pressure reservoir is desired. Since the intentional pressure drop in this type of high pressure reservoir has not been possible so far, the control scheme of the actuator had to be changed instead at low engine speeds. This can be omitted in the method constructed in accordance with the invention.

In another embodiment, it is proposed that constant pressure retention and pressure drop are combined with the control or regulation of the feed rate through the pressure pump through the simultaneous connection of the actuator's operating chamber and the low pressure return and the high pressure reservoir. By means of the operating chamber connection mentioned, the pressure in the high pressure reservoir can be affected very quickly and with high dynamics, while the control or regulation of the feed volume via the hydraulic pump allows the pressure in the high pressure reservoir to Can be importantly adapted.

The method according to the invention allows the actuators to be separated from each other through pressure planes of pistons of various sizes and vice versa, the operating chamber being continuously operated at high pressure and the other operating chamber being connected with the high pressure reservoir and the low pressure return. Particular preference is given if it comprises two working chambers. With this type of actuator a very short switching time can be realized, which facilitates the implementation of the method according to the invention.

In order to prevent cavitation during withdrawal of hydraulic fluid from the operating chamber to the low pressure return, the method according to the invention allows the hydraulic fluid to flow from the operating chamber into the low pressure return. Thereby, the pressure difference at the time of withdrawing the hydraulic fluid which prevents generation | occurrence | production of a cavitation is reduced.

The invention relates to a computer program suitable for the execution of the method according to the claims, when executed on a computer. It is particularly advantageous if the computer program is stored in a memory, in particular flash memory or ferrite-RAM.

The invention also relates to a control and regulating device for engine operation in connection with a first control valve and a second control valve of at least one electro-hydraulic valve control device, wherein the operating chamber of the actuator of the gas exchange device is It can be connected with a high pressure reservoir and a low pressure return.

In order to simplify the configuration of the electrohydraulic valve control device, it is proposed that the control and regulating device is suitable for the execution of the above-described method. It is particularly preferred if a computer program of the type described above is provided.

In Fig. 1, the electrohydraulic valve control device is denoted by reference numeral 10 as a whole. The device comprises a reservoir for hydraulic fluid, indicated by reference numeral 12 and which may be an oil sump of the engine. Hydraulic fluid is supplied from the hydraulic reservoir 12 into the high pressure reservoir 16 by an adjustable high pressure hydraulic pump 14. The hydraulic conduit 18 is guided from the high pressure reservoir 16 through the pressure regulating valve 20 to the solenoid valve 22.

Hydraulic conduit 18 is guided from solenoid valve 22 to actuator 24. This means a hydraulic cylinder comprising a double acting piston 26. The piston 26 is guided into the housing 28. In FIG. 1, a first operating chamber 30 is formed between the piston and the housing 28 at the upper end of the piston 26. The operating chamber is connected to the solenoid valve 22. In FIG. 1, a second operating chamber 32 is formed at the lower end of the piston 26 between the piston and the housing 28. The operating chamber is connected via a branch conduit 33 to a cross section of the hydraulic conduit 18 existing between the high pressure reservoir 16 and the solenoid valve 22.

The upper end 34 of the piston 26 in FIG. 1 is generally larger than the lower end 36 of the piston 26 which limits the second operating chamber 32. Thus, the piston 26 here means so-called differential piston. The piston 26 is connected with the gas exchange valve 38. The valve comprises a valve rod 40 and a valve element 42. Through the valve element 42 the opening (not shown) of the combustion chamber 44 can be closed or opened. Combustion chamber 44 is present in engine block 46 of the engine (without reference numeral).

The hydraulic conduit 48 is guided to the low hydraulic reservoir 52 through the second solenoid valve 50 from the first operating chamber 30 of the actuator 24. The low hydraulic reservoir is connected with a low pressure return 56 that returns to the hydraulic fluid reservoir 12 via a pressure regulating valve 54. The hydraulic conduit 58 is returned from the first operating chamber 30 of the actuator 24 to the high pressure reservoir 16 via the pressure regulating valve 60.

Both solenoid valves 22 and 50 are actuated by solenoid controllers 62 and 64 and pressurized by pressure springs 66 and 68 respectively in the stationary switching position. The first solenoid valve 22 is closed at the stop switching position 70 in which no current flows to the solenoid controller 62 and vice versa to open at the operating switching position 72. In contrast, the second solenoid valve 50 is opened at the stop switching position 74 and is closed at the operating switching position in which current flows to the solenoid controller 64. The switching position is indicated by reference numeral 76.

The electrohydraulic valve control device 10 includes a control and regulation device 78. The device is connected to solenoid controllers 62 and 64. The apparatus may also control the hydraulic pump 14. At the inlet surface, a control and regulation device 78 is connected with a pressure sensor 80 which detects the pressure in the high pressure reservoir 16. The control and regulation device 78 is also connected to a speed indicator for the crankshaft of the engine. The speed indicator is indicated by reference numeral 82.

The electrohydraulic valve control device 10 is operated in the following manner (the method described below is stored in a ferrite ram (not shown) of the control and regulating device 78 as a computer program). In order to open the gas exchange valve 38, the piston 26 of FIG. 1 must be moved downward. This is achieved by closing the second solenoid valve 50 with current flowing from the stop switching position 74. Thus, the connection of the first operating chamber 30 and the low hydraulic reservoir 52 is stopped.

In addition, since the solenoid controller 62 of the first solenoid valve 22 flows current by the control and regulating device 78, the solenoid valve 22 is opened in the switching position from the closed stop switching position 70. Go to 72. Thus, the first operating chamber 30 is connected to the high pressure reservoir 16. Thus, in the first operating chamber 30, the hydraulic force existing in the high pressure reservoir 16 is adjusted.

Within the two operating chambers 30, 32 of the actuator 24 there is the same pressure, ie the pressure which is generally present in the high pressure reservoir 16 but the lower end 36 of the piston is the upper end 34 of the piston 26. Since smaller, the generated force appears downward in FIG. 1 whereby the piston 26 is moved in this direction. Thus, the valve rod 40 and the valve member 42 move downward in FIG. 1 to open the gas exchange valve 38.

When the gas exchange valve 38 is closed again, since the first solenoid valve 22 is connected from the control and regulating device 78 without current flow, the valve is opened from the open switching position 72 to the pressure spring 66. Is pressed into the closed switching position 70. Thus, the connection between the high pressure reservoir 16 and the first operating chamber 30 is again interrupted.

Since the second solenoid valve 50 is connected without current flow by the control and regulating device 78, the valve is a stop switching position 74 opened from the switching position 76 closed by the pressure spring 68. Is moved to. The first operating chamber 30 is again connected to the low hydraulic reservoir 52. Thus, the pressure in the first operating chamber 30 drops until the force for moving the piston 26 back up is adjusted. This closes the gas exchange valve 38.

When the pressure in the high pressure reservoir 16 is higher than the target pressure is reported to the control and adjustment device 78 via the pressure sensor 80, the first solenoid valve 22 is controlled at the open switching position 72. And controlled by the adjusting device 78, on the contrary, the second solenoid valve 50 stays in the open stop switching position 74. At this time, it is assumed that the engine is in an operating state in which the gas exchange valve 38 connected with the actuator 24 is to be closed. Low hydraulic pressure storage from the high pressure reservoir 16 through the first solenoid valve 22, the first operating chamber 30 and the second solenoid valve 50 through the operation of the first solenoid valve 22 mentioned. Group 52 is directly connected.

Through the corresponding configuration of the hydraulic conduits 18, 48, in this state, the pressure in the first operating chamber 30 is not increased, and unwanted movement of the piston 26 can be induced. By connecting directly from the high pressure reservoir 16 to the low hydraulic reservoir 52, the hydraulic fluid flows directly from the high pressure reservoir 16 to the low hydraulic reservoir 52 without operating the actuator 24. Can be. In this way, the pressure in the high pressure reservoir 16 can be intentionally reduced or kept constant.

If the gas exchange valve 38 is reliably prevented from being able to open during the above state, the high pressure reservoir when the valve element 42 is pressurized in the closed position based on the high pressure present in the combustion chamber 44 A direct connection is preferably provided between the 16 and the low hydraulic reservoir 52.

The hydraulic fluid flow from the high pressure reservoir 16 to the low pressure reservoir 52 is controlled and regulated by the 78 and the first solenoid valve 22 is again connected without current flow and the closed stop switching position 70. It simply exits by returning from). The pressure present in the low hydraulic reservoir 52 is readjusted in the first operating chamber 30.

However, the electrohydraulic valve control device 10 is operated in other ways to keep the pressure in the high pressure reservoir 16 constant and drop.

The connection of the high pressure reservoir 16 and the low oil pressure reservoir 52 may be combined with the operation of the actuator 24. The solenoid of the second solenoid valve 50 which opens the gas exchange valve 38 during actuation of the actuator 24, for example, the solenoid valve reaching the closed switching position 76 at the open stop switching position 74. Immediately before current flows into the controller 64, the solenoid valve 22 can be operated at the closed stop switching position 70 and controlled to the open switching position 72.

As such, the second solenoid valve 50 is closed immediately before, and is directly connected between the low pressure reservoir 52 and the high pressure reservoir 16, from which the hydraulic fluid can be withdrawn from the high pressure reservoir 16. . Immediately before the current-free connection of solenoid controller 62 to first solenoid valve 22 the gas exchange valve 38 is closed again, thereby closing the solenoid valve from the open switching position 72 to the closed switching position 70. And the second solenoid valve 50 can be equally moved from the closed switching position 76 to the open stop switching position 74.

This results in a short time direct connection from the high pressure reservoir 16 to the low oil pressure reservoir 52 and the low pressure return 56, whereby the hydraulic fluid is withdrawn from the high pressure reservoir 16 so that the pressure is reduced. It may be kept constant or descended.

By such a short time operation of the valve and the direct connection of the high pressure reservoir 16 and the low oil pressure reservoir 52, the pressure in the high pressure reservoir 16 can be kept constant as can be seen in FIG. Can be. The amount of fluid withdrawn is controlled through the duration of the direct connection. In this figure the corresponding no-operation pressure of solenoid valves 22, 50 is shown in dashed lines, and the pressure progression provided by the corresponding operation of solenoid valves 22, 50 is shown in solid lines.

When the engine is operated at a low speed, it is detected by the engine speed indicator 82 so that a corresponding signal is sent to the control and adjustment device 78. The control and adjustment device may be controlled such that the pressure in the high pressure reservoir 16 drops. Typically the working pressure of 200 bar drops to approximately 50 bar. When the engine speed rises again, since the hydraulic connection between the high pressure reservoir 16 and the low pressure return is prevented, the pressure is driven by the hydraulic pump 14 in the high pressure reservoir 16 on the basis of a continuous supply. Is raised again. The correlation between the engine speed n and the pressure P in the high pressure reservoir 16 is shown in FIG. Pressure adjustment in the high pressure reservoir 16 is optionally supported by corresponding control of the high pressure hydraulic pump 14.

Claims (12)

The actuator 24 is connected to the high pressure reservoir 16 and separated from the low pressure return 56 so that the actuator 24 is operated from the first position to the second position, on the contrary, the actuator 24 is operated from the second position to the first position. At least one actuator 24 which is connected to the low pressure return section 56 and which is separated from the high pressure reservoir 16, and which acts on the gas exchange valve 38. In the operating method of the electrohydraulic valve control device 10 of the engine, A constant pressure retention or pressure drop in the high pressure reservoir (16) is characterized in that the operating chamber (30) is generated by simultaneous connection with the high pressure reservoir (16) and the low pressure return (56). 2. The operating chamber 30 of the actuator 24 is simultaneously with the high pressure reservoir 16 and the low pressure return 56 in order to maintain a constant pressure or drop in the high pressure reservoir 16. And the attached gas exchange valve (38) is immediately closed. 3. The operating chamber 30 of the actuator 24 is simultaneously with the high pressure reservoir 16 and the low pressure return 56 in order to maintain a constant pressure or drop in the high pressure reservoir 16. And the attached gas exchange valve (38) cannot be opened immediately due to the high pressure in the combustion chamber (44). The high pressure reservoir (16) of any one of the preceding claims, wherein the operating chamber (30) of the actuator (24), which must be moved from the first position to the second position, immediately before being separated from the low pressure return section (56). The operating chamber 30 of the actuator 24, which is to be connected to and / or to be moved from the second position to the first position, is connected with the low pressure return 56 just before disconnecting from the high pressure reservoir 16. Characterized in that the method. In any one of the preceding claims, when the engine is operated at low rotational speed, the operating chamber 30 of the actuator 24 is temporarily simultaneously connected with the high pressure reservoir 16 and the low pressure return 56. Characterized in that the method. Method according to any of the preceding claims, characterized in that the control or regulation of the feed amount is further carried out via a hydraulic pump (14). Actuator 24 according to any one of the preceding claims comprises two operating chambers 30, 32 separated from one another via pressure surfaces 34, 36 of piston 26 acting opposite each other in different sizes, The operating chamber (32) is operated continuously by high pressure, and the other operating chamber (30) can be connected with the high pressure reservoir (16) and the low pressure return (56). Method according to any of the preceding claims, characterized in that the hydraulic fluid flows from the operating chamber (30) into the low hydraulic reservoir (52). Computer program, when executed on a computer, suitable for the execution of the method according to any one of the preceding claims. 10. A computer program according to claim 9, stored in a memory, in particular flash memory or ferrite-RAM. The operating chamber 30 of the actuator 24 of the gas exchange valve 38 is connected at least with the first control valve 22 and the second control valve 50 of the electrohydraulic valve control device 10. In the control and regulating device for operating the engine, which can be connected to the high pressure reservoir 16 or the low pressure return 56, Control and adjustment device, characterized in that it is suitable for the execution of the method according to any of the preceding claims. 12. Control and adjustment device according to claim 11, characterized in that a computer program according to any one of claims 9 or 10 is provided.