EP1415070A1

EP1415070A1 - Device for controlling gas exchange valves

Info

Publication number: EP1415070A1
Application number: EP02745076A
Authority: EP
Inventors: Udo Diehl; Bernd Rosenau; Uwe Hammer; Volker Beuche; Peter Lang; Stefan Reimer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2001-07-24
Filing date: 2002-05-23
Publication date: 2004-05-06
Anticipated expiration: 2022-05-23
Also published as: US20040035379A1; WO2003012263A1; EP1415070B1; KR20040019331A; DE50209020D1; JP2005508469A; US6889639B2; BR0205797A; DE10136020A1

Abstract

The invention relates to a device for controlling the gas exchange valves of an internal combustion engine that have respective hydraulic valve adjusters (11) associated with one gas exchange each comprising an adjustment plunger (13) acting on the gas exchange valve and two hydraulic working chambers (121, 122) that are limited by the adjustment plunger (13). The first working chamber (121) that impinges the gas exchange valve (10) in the closing direction is constantly filled with a pressurized fluid, and the second working chamber (122) that impinges the gas exchange valve (10) in the opening direction is alternately filled with a pressurized fluid and relieved via a first and second electric control valve (24, 25 and 26, 27, respectively) In order to reduce the cost of production of such a valve, two valve adjusters (11) each are alternately actuated by the same first and the same second control valve (24 or 26, 25 or 27) and the control valves (24, 25 or 26, 27) are switched during the closed state of the two gas exchange valves (10) that are actuated by said valve adjusters (11).

Description

Device for controlling gas exchange valves

State of the art

The invention relates to a device for controlling gas exchange valves in combustion cylinders of an internal combustion engine according to the preamble of claim 1.

In a known device of this type (DE 198 26 047 AI), each valve actuator, the actuating piston of which is connected in one piece to the valve tappet of the associated gas exchange valve, is constantly connected to a high-pressure source with its first working chamber and, on the one hand, to a supply line to the one with its second working chamber High-pressure source alternately closing or releasing first electrical control valve and on the other hand connected to a second control valve alternately releasing or closing a relief line. The electrical control valves are designed as 2/2 solenoid valves with spring return. With de-energized control valves, the first work area is still under high pressure, while the second work space is separated from the high pressure source and connected to the relief line. The gas exchange valve is closed. Both control valves are energized to open the gas exchange valve. Due to the switching control valves, the second working space of the valve actuator is blocked on the one hand by the second control valve with respect to the relief line and on the other hand connected to the supply line to the high pressure source by the first control valve. The gas exchange valve opens, the size of the opening stroke depending on the formation of the electrical control signal applied to the first electrical control valve and the opening speed on the pressure applied by the high pressure source. In order to keep the gas exchange valve in a certain open position, the first control valve is then switched off so that it shuts off the supply line to the second working area of the valve actuator. In this way, all valve opening positions of the gas exchange valve can be set by means of an electrical control device for generating control signals. To control a gas exchange valve, two electrical control valves are required, which act accordingly on the assigned valve actuator with hydraulic pressure.

Advantages of the invention

The device according to the invention for controlling gas exchange valves with the features of claim 1 has the advantage that through the use of a control valve pair composed of an extreme and a second electrical control valve for the alternate actuation of the whole two valve actuators, two electrical control valves per pair of valve actuators can be saved. Since the electrical control valves, which are primarily designed as 2/2 solenoid valves, have to realize extremely short switching times, in practice approx. 0.3 ms with an opening cross section of 3 mm ² , such control valves are very expensive, so that the number of control valves is reduced in the control device brings significant cost savings. The smaller number of electrical control valves also reduces the number of output stages and the amount of electrical wiring required to control the control valves, which leads to further cost savings.

The measures listed in the further claims allow advantageous developments and improvements of the device for controlling gas exchange valves specified in claim 1.

According to a preferred embodiment of the invention, the switching of the control valves is carried out by means of two switching valves designed as 3/2-way valves, three of which are controlled valve connections, the first of which is connected to the first or second electrical control valve and the two which can be connected alternately to the first valve connection further valve connections are connected to the second work spaces of the two valve actuators. Simple switching valves that can ^'be driven electrically or hydraulically, are bulk buying very cheap, especially if no quick

Switching times are required. For example, with one Four-cylinder four-stroke engine of the common closing state of two gas exchange valves in combustion ^cylinders' it a 360 ° -Kurbelwinkelversatz their ignition points extends over a crank angle range of about 60 °, a sufficiently large time period for reversing the changeover valves are available. Through the use of the inexpensive changeover valves, the total number of valves is increased again, but a significant cost saving potential remains. The changeover valves are, especially if they are hydraulically controlled, in the

Compared to the 2/2-way solenoid valves quite small, so that the space required for the valve control device is reduced compared to the known valve control.

According to an advantageous embodiment of the invention ^, there is a permanent hydraulic pressure at the control input of the hydraulically controlled changeover valves, which is increased by means of a reciprocating piston to change the changeover valves into their working position. ^'The reciprocating piston is for this purpose driven by a rotating with respect to the speed of the crankshaft halved speed cam for reciprocating movement in a standing with the respective control input in communication pressure chamber. This design measure allows the changeover of the changeover valves to be synchronized with the crankshaft rotation in a simple manner. drawing

The invention is described below with reference to an embodiment shown in the drawing. Show it:

Fig. 1 is a circuit diagram of a device for controlling four in different

Combustion cylinders arranged in a four-cylinder internal combustion engine

Gas exchange,

2 shows a schematic representation of a gas exchange valve in a combustion cylinder of the internal combustion engine,

3 shows a diagram of the valve lift of various valves in the device according to FIG. 1 as a function of the crank angle.

Description of the embodiment

The device shown in FIG. 1 for the control of gas exchange valves in combustion cylinders of an internal combustion engine serves to control a total of four gas exchange valves 10 (FIG. 2), one of which is arranged in a combustion cylinder of a four-cylinder, four-stroke internal combustion engine. The gas exchange valves 10 can be the intake valves or the exhaust valves of the combustion cylinders. The combustion cylinders, not shown here, are symbolic with 03/012263

- 6 -

I, II, III and IV, which are assigned to the valve actuators 11 for the gas exchange valves 10 of the respective combustion cylinder in FIG. 1.

The device has a total of four hydraulic valve actuators 11, each of which is assigned to a gas exchange valve 10 in the combustion cylinders I-IV. Each valve actuator 11 has a working cylinder 12 in which an actuating piston 13 is guided so as to be axially displaceable. The actuating piston 13 divides the working cylinder 12 into two hydraulic working spaces 121 and 122 defined by it and is firmly connected to the valve tappet 14 of the gas exchange valve 10. A valve actuator 11 in connection with a gas exchange valve 10 is shown schematically in an enlarged representation in FIG. 2. The valve tappet 14 carries at its end remote from the actuating piston 13 a plate-shaped valve sealing surface 15 which cooperates with a valve seat surface 17 formed on the housing 16 of the combustion cylinder of the internal combustion engine to control an opening cross section. The

Working cylinder 12 has a total of three hydraulic connections, of which two hydraulic connections 122a and 122b open in the second working space 122 and one hydraulic connection 121a in the first working space 121.

The device also has a pressure supply device 22, which consists of a fluid reservoir 18, a prefeed pump 29, a high pressure pump 19, a check valve 20 and a memory 21 for pulsation damping and energy storage. The output 221 of the tapped between the check valve 20 and the memory 21 Pressure supply device 22 is connected to all via a line 23. Hydraulic connections 121a of the four valve actuators 11 connected, so that the first working spaces 121 of the. Valve actuator 11 is constantly acted upon by the hydraulic pressure present at the outlet 221 of the pressure supply device 22.

• The second working spaces 122 of the working cylinders 12 can be connected on the one hand via first electrical control valves 24 and 26 to the outlet 221 of the pressure supply device 22 and on the other hand via second electrical control valves 25 and 27 to a relief line 28, which in turn opens into the fluid reservoir 18. All control valves 24 - 27 are designed as 2/2-way solenoid valves with spring return. In each case a first control valve 24 or 26 and a second

Control valve 25 and 27 form a pair of control valves with which two valve actuators 11 are alternately actuated. The two valve actuators 11 controlled by the control valve pairs 24, 25 and 26, 27 are each associated with gas exchange valves 10 in those combustion cylinders whose ignition times are offset from one another by a crank angle of 360 °. Thus, the control valve pair 24, 25 controls the two valve actuators 11 of the gas exchange valves 10 in the first and third combustion cylinders I and III and the control valve pair 26, 27 controls the valve actuators 11 for the gas exchange valves 10 in the second and fourth combustion cylinders II and IV, whereby ^' the control each of the two valve actuators 11 takes place alternately and the switching of the control valve pair 24, 25 or 26, 27 from one valve actuator 11 to the other valve actuator 11 during the closed state of the two of the Valve actuators 11 operated gas exchange valves 10 is performed. The changeover of the two control valves 24 and 25 or 26 and 27 of each control valve pair • takes place synchronously.

To switch over the two pairs of control valves 24, 25 and 26, 27 from one valve actuator 11 to the other valve actuator 11, changeover valves 30-33 are used, which in the exemplary embodiment in FIG. 1 are designed as hydraulically controlled 3/2-way valves with spring return. Each changeover valve 30-33 has two switching positions and three controlled valve connections 34-36, of which the first valve connection 34 is connected to the respectively associated control valves 24 and 25 or 26 and 27 and the other two can be connected to the first valve connection 34

Valve connections 35 and 36 are connected to the second working spaces 122 of the valve actuator 11. Thus, in the changeover valve 30, the first valve connection 34 with the first control valve 24, the second valve connection 25 with the second working chamber 122 of the valve actuator 11 is for the first

Combustion cylinder I and the second valve connection 36 are connected to the second working chamber 122 of the valve actuator 11 for the third "combustion cylinder III. The first valve connection 34 of the changeover valve 31 is connected to the second control valve 25, the second valve connection 35 to the second working chamber 122 of the valve actuator 11 for the first combustion cylinder I and the third valve connection 36 are connected to the working space 122 of the valve actuator 11 for the third combustion cylinder III. The same applies to the changeover valves 32, 33 in connection with the Control valve pair 26, 27 and the valve actuators 11 for the second and fourth combustion cylinders II and IV.

The switching valves 30-33 are controlled hydraulically against the spring force of a return spring, for which purpose the control inputs of the switching valves 30 and 31 are connected via a check valve 37 and the control inputs ^{' of} the switching valves 32 and 33 via a check valve 38 are connected to the outlet of the pre-feed pump 29. The changeover valves 30-33 are designed so that they cannot be moved out of their rest position shown in FIG. 1 by the hydraulic pressure present at the outlet of the prefeed pump 29. To switch the changeover valves 30 - 33, the hydraulic pressure at the control inputs is controlled by means of a lifting piston 40 and 41

Changeover valves 30 - 34 enlarged. Each reciprocating piston 40 or 41 delimits a fluid-filled pressure chamber 42 or 43 which is connected to the outlet of the prefeed pump 29 and is driven by a cam 44 or 45 for the stroke movement. The pressure chamber 42 is connected to the control inputs of the changeover valves 30 and 31 and the pressure chamber 43 to the control inputs of the changeover valves 32, 33. The two cams 44, 45 rotate at half the speed of the crankshaft, with each cam revolution the hydraulic pressure applied to the control inputs increasing from the pressure level at the outlet of the pre-feed pump 29 to a maximum pressure required for switching the changeover valves 30-33 and back to the original pressure level is reduced. By moving the pistons 41 and 42 in FIG. 1 upward, the pressure is increased and the associated changeover valves 30-33 switch over. The pistons 41, 42 are reset by the restoring force of the return springs of the changeover valves and by the permanent pressure of the pre-feed pump 29. The pre-feed pump 29 also compensates for leakage losses.

The operation of the device described is described in more detail below with reference to FIG. 3. 3 shows the valve lift as a function of the crank angle for the various valves. Diagrams a, b, f and g each show the valve lift of the gas exchange valves 10 forming intake valves in the first, third, second and fourth combustion cylinders I, III, II and IV, diagram c the valve lift of the changeover valves 30 31, diagram h the valve lift of the changeover valves 32 and 33, diagram d the valve lift of the control valve 24, diagram e the valve lift of the control valve 25, diagram i the valve lift of the control valve 26 and diagram k the valve lift of the control valve 27.

Basically, each gas exchange valve 10 is controlled by the associated valve actuator 11 in such a way that to close the gas exchange valve 10, the second working chamber 122 of the valve actuator 11 is connected to the relief line 28 via the second electrical control valve 25 or 27 and via the first electrical control valve 24 or 26 is blocked by the outlet 221 of the pressure supply device 22. Due to the system pressure prevailing in the first working chamber 121 of the valve actuator 11, the actuating piston 13 in FIG. 2 is shifted upward until the valve sealing surface 15 of the gas exchange valve 10 rests on the valve seat surface 17 on the housing 16 of the combustion cylinder of the internal combustion engine. The actuating piston 13 takes the Position shown in Fig. 1 within the working cylinder 12 of the valve actuator 11. All control valves 24-27 are de-energized and assume their basic or rest position. To open the gas exchange valve 10, the second electrical control valve 25 or 27 is transferred into its blocking position, in which the second working space 122 is blocked off from the relief line 28, and the first electrical control valve 24 or 26 is transferred into its working position, so that the second working space 122 is connected to the outlet 221 of the pressure supply device 22 and the system pressure is now also present in the second working space 122 of the valve actuator 11. Since the piston area of the actuating piston 13, which delimits the first working chamber 121, is smaller than the area of the actuating piston 13, which delimits the second working chamber 122, one is created

Displacement force which moves the actuating piston 13 to the right in FIG. 1 or downwards in FIG. 2, which causes the

Gas exchange valve 10 is opened. The. The size of the opening stroke of the gas exchange valve 10 depends on the opening duration and opening speed of the first control valve 24 or 26.

Once the desired stroke of the gas exchange valve 10 has been reached, the energization of the first control valve 24 or 26 is released and the first control valve 24 or 26 falls back into its blocking position. The pressure in the second working space 122 is maintained, so that the gas exchange valve 10 maintains the opening stroke that has been occupied. To close the gas exchange valve 10, the second control valve 25 or 27 is then de-energized. Diagram d shows the activation of the first control valve 24, diagram e the Activation of the second control valve 25. Diagram i shows the activation of the first control valve 26 and diagram k the activation of the second control valve 27. The first control valves 24 and 26 are blocked when de-energized while the second control valves 25, 27 are open when de-energized.

In order to control the valve actuator 11 assigned to the gas exchange valve 10 in the combustion cylinder I, the changeover valves 30, 31 are in the rest or basic position A shown in FIG. 1, as shown by diagram c in FIG. 3. The valve lift of the gas exchange valve 10 in the cylinder I as a function of the crank angle is shown in diagram a.

To control the valve actuator 11 to actuate the one assigned to the third combustion cylinder III

Gas change valve 10, the two changeover valves 30, 31 are reversed in their working position B. As a result, the second working chamber 122 of the valve actuator 11 is connected to the two control valves 24, 25 for actuating the gas exchange valve 10 in the third combustion cylinder III. The valve control process for the gas exchange valve 10 in the combustion cylinder III then proceeds in the same way as described above for the combustion cylinder I. Diagram b shows the stroke of the gas exchange valve 10 in the combustion cylinder III as a function of the crank angle, while the changeover valves 30, 31 are in position B (diagram c). As can be seen from the diagrams a, b and c, the closing times of the gas exchange valves 10 in the combustion cylinders I and III, which approximately corresponds to the ignition times in the combustion cylinders I and III, are offset by a crank angle of 360 °. At a maximum opening angle of the gas exchange valves 10 of about 240 ° stands for the changeover of the two changeover ^valves' 30, are closed in the crank angular range in both -the gas exchange valves 10 in the cylinder I and III 31, sufficient time is available. This switching range is denoted by S in diagram c and covers approximately 60 ° crank angle.

In the lower part of FIG. 3 with the diagrams f - k, the corresponding conditions for controlling the gas exchange valves 10 in the combustion cylinders II and IV are shown. The diagrams correspond to the diagrams a - e described and are only shifted by a crank angle of 180 °. In this respect, the above statements also apply to the control valves 26 and 27 in connection with the changeover valves 32, 33.

As can be seen from the diagrams c and h in Fig. 3, the changeover valves 30, 31 and 32, 33 are each in a crank angle range of about 300 ° in position A and position B. The corresponding switch is by the

Cams 44, 45 causes that rotate at half the crankshaft speed.

The invention is not restricted to the exemplary embodiment described. For example, the changeover valves cannot be operated hydraulically but electrically, with the de-energized changeover valve in position A and the energized changeover valve in position B or vice versa. It is also possible, in the case of the hydraulically controlled changeover valves 30-33 described, instead of the

Spring return a second hydraulic control input, which counteracts the first to ^' provide.

Claims

Expectations

1.Device for controlling gas exchange valves in combustion cylinders of an internal combustion engine, each with a gas exchange valve (10) assigned to _^ hydraulic valve actuators (11), each having an actuating piston (13) acting on the gas exchange valve (10) and two hydraulic pistons limited by the actuating piston (13) Have working spaces (121, 122), of which the first working space (121) acting on the gas exchange valve (10) in the closing direction is constantly filled with a pressurized fluid and the second working space (122) acting on the gas exchange valve (10) in the opening direction first and second electrical control valve (24 and 25 or 26 and 27) can be alternately filled and relieved with a pressurized fluid, characterized in that two valve actuators (11) each from the same first control valve (24 or 26) and the same second Control valve (25 or 27) are controlled and the switching of the first and second St control valve (24 and 25 or 26 and 27) from one to the other valve actuator (11) during the closed state of the two gas exchange valves (10) actuated by these valve actuators (11).

2. Device according to claim 1, characterized in that the two of the same control valves (24, 25 and 26,

27) controlled valve actuators (11) are each assigned to a gas exchange valve (10) in such combustion cylinders (I, III or II, IV), the ignition times of which are offset by a crank angle of 360 °.

3. Apparatus according to claim 1 or 2, characterized in that the switching of the control valves (24, 25 or 26, 27) from one to the other valve actuator (11) takes place synchronously.

4. Device according to one of claims 1 - ^' 3, characterized in that the switching of the control valves (24, 25 or 26, 27) each by means of two 3/2-way valves designed switching valves (30, 31 or 32, 33rd ) each with two switching positions and three controlled valve connections (34, 35, 36), of which a first valve connection (34) with the first or second electrical control valve (24 or 25) and two alternately on the first valve connection (34 ) connectable further valve connections (35, 36) are connected to the second work spaces (122) of the two valve actuators (11).

5. Device according to one of claims 1-4, characterized in that the switching valves (30 - 33) each have a hydraulic control input with spring return.

6. Device according to one of claims 1-5, characterized in that the switching of the switching valves (30 - 33) is derived from the rotary movement of a crankshaft of the internal combustion engine.

7. Apparatus according to claim 5 and 6, characterized in that a permanent hydraulic pressure is present at the control input of the changeover valves (30 - 33) and that the hydraulic pressure can be varied by means of a reciprocating piston (40, 41), which from one with the Crankshaft speed halved speed revolving cam (44, 45) can be driven.

8. The device according to claim 7, characterized in that the control inputs of the switching valves (30 - 33) via a check valve (37, 38) at a constant hydraulic pressure supplying, preferably as

Pre-feed pump (29) trained pressure source are connected and that the spring force of the spring return is set so that the restoring force generated by it is little greater than the valve switching force generated by the hydraulic pressure of the pressure source at the control input.

9. Device according to one of claims 5-8, characterized in that the two valve actuators (11) assigned two changeover valves (30, 31 and 32, 33) to a valve unit with a common hydraulic control input with spring return are summarized.

10. Device according to one of claims 1-9, characterized in that the gas exchange valves (10) are used as inlet and / or outlet valves for the combustion cylinders of the internal combustion engine.