KR20040077808A - Device for controlling charge exchange valves - Google Patents

Abstract

The present invention relates to a gas exchange valve control device, wherein at least one of the gas exchange valves is assigned to the combustion chamber of the internal combustion engine as inlet valve 11 and also at least one as discharge valve 12, the device being gas exchange An electrohydraulic valve actuator 18 each assigned to the valve for actuating the valve, and a pressure supply unit 26 for supplying high pressure fuel to the valve actuator 18 and having a high pressure pump and an accumulator unit. In order to reduce the energy received by the control device, the accumulator unit comprises two separate high pressure reservoirs 31, 32, one of which is connected to the valve actuator 18 for at least one inlet valve 11, the other One is connected to a valve actuator 18 for at least one outlet valve 12. By means of the diverting member 30, the high pressure pump 27 can optionally be connected to one or another high pressure reservoir 31, 32 and a return line 37 which is directed to the fluid reservoir 29.

Description

Device for controlling charge exchange valves

In a known arrangement of such a configuration (DE 198 26 047 A1), each electrohydraulic valve actuator comprises a regulating piston acting on a gas exchange valve and two hydraulic actuating chambers defined by the regulating piston. The first working chamber which affects the gas exchange valve in the closed direction of the working chamber is constantly filled with high pressure fuel and the second working chamber which affects the gas exchange valve in the open direction is provided by the first and second electric control valves. Alternately can be filled and emptied with high pressure working medium or fluid. For this purpose the pressure supply device supplies a high pressure fuel which is provided on the one hand to the first working chamber and on the other hand to the second working chamber by the first electrical control valve. The second working chamber is connected by a second electrical control valve to the return line returned to the fluid reservoir. The pressure supply includes an operating pressure accumulator, a regulated regulating pump, which supplies fluid from the fluid reservoir to the operating pressure accumulator through a check valve. In the closed state of the gas exchange valve, the second operating chamber is disconnected from the pressure supply via the closed first control valve and connected to the return line through the open second control valve, so that the regulating piston is connected to the fluid in the first operating chamber. Through pressure it is switched to its closed position. The control valve is opened to open the gas exchange valve so that the second working chamber is disconnected from the return line and connected to the pressure supply. The regulating piston moves towards the first working chamber with the gas exchange valve open because the piston face of the regulating piston in the second working chamber is larger than the working surface of the regulating piston in the first working chamber, and the size of the opening stroke is zero. In the formation of the electrical control signal applied to the one control valve, the opening speed depends on the fluid pressure controlled by the pressure supply device. The control valve is switched back to close the gas exchange valve. The second working chamber, which is shut off with respect to the pressure supply, is thus located in the return line, and the fluid pressure in the first working chamber returns the regulating piston to its valve closed position, so that the gas exchange valve is closed by the regulating piston.

The present invention relates to a device for controlling a gas exchange valve according to the preamble of claim 1.

1 is a circuit diagram of an apparatus for control of a gas exchange valve for an internal combustion engine.

FIG. 2 is a detailed circuit diagram of an electrohydraulic valve actuator for operating a gas exchange valve in the control device according to FIG. 1.

An apparatus according to the invention for controlling a gas exchange valve having the features of claim 1 is provided with an accumulator unit for separating the fluid supply of the valve actuator to at least one inlet valve on the one hand and at least one outlet valve on the other hand. Divided into these two high pressure reservoirs, the fluid pressure in the two high pressure circuits for the inlet and outlet valves, as needed, is controlled by the valves such as valve operating time, stroke, stroke speed and valve opening duration in the degrees of freedom possible through electrohydraulic valve control. Different pressure levels can be realized in the control. Thus it is possible, for example, to design the fluid pressure in the high pressure circuit for the inlet valve to be lower than the fluid pressure in the high pressure reservoir for the outlet valve, the fluid pressure being required by the outlet valve and preset by the force preset through the combustion chamber pressure. . As the pressure in the high pressure circuit drops, the required energy can be reduced. As a result, the hydraulic valve actuators for the inlet and outlet valves can be unified because the greater force required to operate the outlet valves against the combustion chamber pressure is realized by the greater force in the assigned high pressure circuit. In addition, the switching member is selectively controlled for selective supply to both high pressure reservoirs so that moments can be compensated for energy reception. This results in a uniform moment action that has less impact on ride comfort.

Through the measures recited in another claim, further preferred embodiments and improvements of the gas exchange valve control device as set forth in claim 1 are possible.

The pressure supply device according to the invention can be used as a structurally simple stationary pump instead of the technically complicated conventional regulating pumps which are generally used by being divided into two high-pressure circuits separated for inlet and outlet valves. A significant savings in manufacturing costs can be achieved. Known fixed pumps are characterized in that they provide only a conveying or volumetric stream which depends only on the drive speed, independent of the conveying pressure. The stationary pump may be operated by a connected transfer pump, such as an oil pump of an internal combustion engine or as a self-priming pump.

According to a preferred embodiment of the present invention, the switching member for alternately connecting the two high pressure reservoirs to the fixed pump is formed as a 4/3 directional valve having a spring return position. Of the three valve outlets of the magnetic valve, the first outlet is connected to the high pressure reservoir, the second outlet is connected to the other high pressure reservoir, and the third outlet is connected to the return line, while the valve inlet of the magnetic valve is connected to the pump output of the fixed pump. do.

The invention is explained in more detail below by the examples shown in the drawings.

The device for controlling gas exchange valves, shown in the circuit diagram in FIG. 1, controls the four inlet valves 11 and four outlet valves 12 of the internal combustion engine as a whole by the electronic control device 13 in the selected embodiment. However, the number of inlet and outlet valves 11 and 12 can vary. Each inlet and outlet valve 11, 12 is arranged in the cylinder head 14 of the combustion cylinder, which is shown fragmentally in FIG. 2, and hermetically closes the combustion chamber formed in the combustion cylinder. Each gas exchange valve comprises a valve seat 16 and a valve member 17 surrounding the cross section 15 of the cylinder head 14 in a known manner, the valve member being guided to move axially. With a valve closure body seated on 171, the valve closure body interacts with the valve seat 16 for closure and release of the open cross section 15. As the valve stem 171 moves in one or the other axial ring, the valve closing body 172 is lifted from or seated on the valve seat 16.

In the control device for the gas exchange valve, an electrohydraulic valve actuator 18 is arranged for each operation of each gas exchange valve, that is, each of the inlet valve 11 and the outlet valve 12. Known electrohydraulic valve actuators 18 are shown in detail in FIG. 2. The valve actuator comprises a dual acting hydraulically actuated cylinder 19 and two electrically controlled valves 20, 21, which are preferably formed as 2/2 directional magnetic valves with springs returned. The electric control valves 20, 21 are controlled by the electronic control device 13. The hydraulically actuated cylinder 19 comprises a cylinder housing 22, an adjustment piston 23, which is axially guided therein and connected to the valve stem 171 of the gas exchange valve, in a known manner, wherein the adjustment piston is a cylinder. The inner space of the housing 25 is divided into a first operating space 24 and a second operating space 25. The first operating space 24 is directly connected, and the second operating space 25 is connected to the hydraulic input 181 of the valve actuator 18 by the first electric control valve 20. The second working space 25 is connected to the hydraulic output 182 of the valve actuator 18 by a second electric control valve 21. The manner of operation of the valve actuator 18 for opening and closing the arranged gas exchange valve is known and described in the introduction of the prior art.

With the electrohydraulic valve actuator 18, the control device comprises a pressure supply 26 for supplying a high pressure working medium or fluid. The pressure supply device 26 includes a fixed pump 27 for generating a high pressure, a switching member 30 connected to a pump outlet of the fixed pump, and two high pressure reservoirs 31 and 32, wherein the fixed pump It is supplied from the fluid reservoir 29 by the preliminary transfer pump 28 and the high pressure reservoirs are pumped out of the fixed pump 27 by the check valve 33 or 34 alternately according to the switching position of the switching member 30. Can be connected to the unit. The first high pressure reservoir 21 is at the first output 261 of the pressure supply, the second high pressure reservoir is at the second output 262 of the pressure supply, and each of the high pressure reservoirs 31, 32 is pressured. The output 261 or 262 of the supply device 26 is connected to the pressure limiting valve 35 or 36, the valve output of which is connected to a return line 37 leading into the fluid reservoir 29. In the illustrated embodiment, the switching element 30 is formed as a 4 / 3-way magnetic valve 41 in which the spring is returned, which is controlled by the electronic control device 13. As a whole, the first valve outlet 412 of the three valve outlets of the magnetic valve 41 is positioned in the first high pressure reservoir 31 by inserting the check valve 33, and the second valve outlet 413 is The check valve 34 is inserted into the second high pressure reservoir 32 and the third valve outlet 414 is connected to the return line 37 or directly to the fluid reservoir 29 by a connection line 42. On the other hand, the valve inlet 411 is connected to the fixed pump 27.

All of the electrohydraulic valve actuators 18 actuating the inlet valve 11 are connected to the first output 261 of the pressure supply device 26 by its hydraulic input 181 and thereby the first high pressure reservoir 31. Is connected to. All hydraulic outputs 182 of the valve actuator 18 are connected to the return line 37 by a common connection line 38. All of the electrohydraulic valve actuators 18 for actuating the outlet valve 12 are connected to the second inlet 262 of the pressure supply device 26 by its hydraulic input 181 and thereby the second high pressure reservoir 32. Is connected to. The hydraulic output 182 of the valve actuator 18 is in turn connected to the return line 37 by a common connection line 39. Check valves 43 or 44 may be arranged in both connecting lines 38 and 39, respectively, which open towards the return line 37.

All gas exchange valves, ie the electrohydraulic valve actuators 18 for all the inlet valves 11 and the outlet valves 12, are implemented in a unified manner. The adjustment force provided by the valve actuator 18 for the discharge valve 12 and preset by the combustion chamber pressure is substantially greater than the adjustment force that the valve actuator 18 must provide to operate the inlet valve 11. The different forces are realized by different pressure levels in the high pressure reservoirs 31, 32. Different pressure levels are obtained by correspondingly adjusting the pressure limiting valves 35, 36. According to the switching position of the 4 / 3-way magnetic valve 41, the high pressure reservoir 32 is fixed by the fixed pump 37 to the preset pressure level through each pressure limiting valve 35 or 36. . Since the high pressure reservoir 31 is fixed at a low pressure level, the energy required for generating pressure is reduced. If no fluid is drawn out by the valve actuator 18 in the two high pressure circuits, the 4 / 3-way magnetic valve 41 is controlled at its central position shown in FIG. 1 where the fluid is stored fluid without pressure. It cycles through the group 29.

Optionally, the fixed pump 27 may be embodied as a self-primed pump. In this case the preliminary transfer pump 28 is omitted and the stationary pump 27 draws the fluid directly from the fluid reservoir 29.

The invention is not limited to the described embodiments. The number of inlet valves 11 and outlet valves 12 operated by the control device can thus vary. In addition, so-called three-valve operation is also possible, in which two inlet valves 11 and one outlet valve 12 are assigned to each combustion chamber of the internal combustion engine formed in the combustion cylinder.

Claims (10)

Apparatus for controlling a gas exchange valve, wherein at least one of the valves is assigned to the combustion chamber of the internal combustion engine as an inlet valve 11 and at least one as an outlet valve 12, the device operating gas exchange valves 11, 12. In the device comprising an electrohydraulic valve actuator (18) each assigned to the valve and a pressure supply device (26) for supplying a high pressure fuel to the valve actuator (18) and having a high pressure pump and an accumulator unit. The accumulator unit comprises two separate high pressure reservoirs 31, 32, one of which is to the valve actuator 18 for at least one inlet valve 11, the other to at least one outlet valve 12. Is connected to a valve actuator 18, and the high pressure pump is connected to the return line 37, which is optionally guided by the switching element 30 to one or the other high pressure reservoirs 31, 32 and the fluid reservoir 29. Device which can be connected. 2. Device according to claim 1, characterized in that the high pressure pump is formed as a stationary pump (27), the pump outlet being located at the input of the diverting member (30). 4. The 4/3 way magnet according to claim 1 or 2, wherein the diverting member (30) comprises one valve inlet (411) and three valve outlets (412, 413, 414) and springs are returned. It is formed as a valve 41, the valve inlet 411 is connected to the pump outlet and one of the three valve outlets (412, 413, 414) in one high pressure reservoir, the other high pressure storage Device (31, 32), characterized in that the third outlet is connected to the return line (37). 4. Device according to claim 3, characterized in that the 4 / 3-way magnetic valve (41) is controlled by an electronic control device (13). 5. The device according to claim 1, wherein the two high pressure reservoirs are fixed at different pressure levels. 6. 6. Device according to claim 5, characterized in that the high pressure reservoir (31, 32) is each connected to the return line (37) by one pressure limiting valve (35, 36). The valve actuator (18) of all the inlet valves (11) is one high pressure reservoir (31, 32) according to any one of the preceding claims. ), The valve actuators (18) of all outlet valves (12) are connected to other high pressure reservoirs (31, 32). Device according to one of the claims 2 to 7, characterized in that the stationary pump (27) is connected to a preliminary transfer pump (28) conveyed from the fluid reservoir (29). 8. The device according to claim 2, wherein the stationary pump (27) is implemented as a self-primed pump, the pump inlet of which is connected directly to the fluid reservoir (29). 9. 10. Each of the electrohydraulic valve actuators 18 comprises a dual acting hydraulic actuating cylinder 19 for valve actuation, the actuating pressure in the actuating cylinder 19. Apparatus comprising an electrical control valve (20, 21) to control the.