DE102010061361A1 - Reversing valve for controlling fluid flow in e.g. petrol engine of person motor car, has switching mechanism for shifting valve from one position into another position by predetermined actuating pressure depending on oil pressure - Google Patents

Abstract

The valve (110) has a switching mechanism for optionally shifting the valve from one switching position into another switching position by predetermined actuating pressure depending on oil pressure in a spark-ignition combustion engine. Two working chambers (82, 92) having certain volume (120) are brought in a fluid communication with each other through a fluid groove. The switching mechanism is designed as a ballpoint pen mechanism. Pressures of the fluid, momentary engine speed and/or momentary compression ratio are detected by pressure sensors. Independent claims are also included for the following: (1) a combustion engine comprising a hydraulically adjustable eccentric-cam device for creating effective connecting rod length (2) a method for controlling a reversing valve.

Description

The present invention relates to a switching valve for controlling a fluid flow, and an internal combustion engine having such a switching valve and a method for controlling the switching valve.

Although applicable to any vehicle, the present invention and the underlying problem with respect to a passenger car will be explained in more detail.

In internal combustion engines, a high compression ratio has a positive effect on the efficiency of the internal combustion engine. Under compression ratio is generally understood the ratio of the entire cylinder space before compression to the remaining cylinder space after compression. In internal combustion engines with spark ignition, in particular gasoline engines, which have a fixed compression ratio, the compression ratio, however, may only be selected so high that so-called "knocking" of the internal combustion engine is avoided during full-load operation. However, for the much more frequently occurring partial load range of the internal combustion engine, ie with low cylinder filling, the compression ratio with higher values could be selected without "knocking" occurring. The important part load range of an internal combustion engine can be improved if the compression ratio is variably adjustable. Various systems are described for adjusting the compression ratio.

The DE 10 2005 055 199 describes a system in which the connecting rod length is variably adjustable. The variation of the connecting rod length is carried out by a rotation of an eccentric connecting rod eye. The rotation of the connecting rod eye is initiated by the action of mass and gas forces of the internal combustion engine, wherein the rotational movement is assisted by acted upon with engine oil piston in the connecting rod. To control the rotational movement of the eccentric connecting rod each one of the piston is pressurized with engine oil, while the other piston is depressurized. The pistons are controlled via a 3/2-way valve. To switch the 3/2-way valve, this must be operated mechanically. For this purpose, a complex solution of slide tracks, switching and push rods, which are driven by an electric motor, for example, provided from outside. However, this requires extensive changes to the internal combustion engine.

Thus, the present invention has for its object to provide an improved changeover valve, which eliminates the disadvantages mentioned above.

This object is achieved by a switching valve with the features of claim 1 and / or by an internal combustion engine with the features of claim 13 and / or a method having the features of claim 16.

Accordingly, it is provided:
A switching valve, in particular for controlling a fluid flow in an internal combustion engine, with a switching mechanism or control mechanism which is adapted to shift the switching valve by a predetermined actuating pressure selectively in a first switching position and a second switching position, whereby each a first working space or a second working space can be brought into fluid communication with a volume, wherein a displacement into the first and / or the second switching position takes place as a function of a momentary pressure of the fluid in the internal combustion engine.

An internal combustion engine having an adjustable compression ratio, comprising: such a switching valve; and a connecting rod assembly with a arranged in a connecting rod eye and / or a Hublagerauge hydraulically adjustable eccentric means for adjusting an effective connecting rod length, wherein an adjustment of the eccentric means of the switching valve is controllable.

A method of controlling a switching valve, the method comprising the steps of: detecting a momentary pressure of the fluid in the internal combustion engine; Comparing the detected instantaneous pressure with predetermined pressure thresholds; and, due to the comparing, controlling the switching valve so that the switching valve is shifted to a first or second switching position.

The basic idea of the present invention is to provide a switching valve for controlling a fluid flow in an internal combustion engine, in which in a first switching position a first working space is in fluid communication with a volume, and in a second switching position a second working space is in fluid communication with the volume. wherein a shift into the first and / or the second switching position in dependence on a current pressure of the fluid in the internal combustion engine takes place.

In the dependent claims are advantageous refinements and improvements of the specified in claim 1 switching valve or specified in claim 13 internal combustion engine and the method specified in claim 16.

According to a preferred development, the changeover valve can be displaced into a third switching position for a transition from one switching position to the other, in which a working chamber currently in fluid communication with the volume remains in this fluid connection until the other switching position is reached.

According to a preferred refinement, the displacement into the first and / or the second switching position additionally takes place as a function of a current engine speed and / or a momentary compression ratio and / or an engine load and / or a mean engine oil pressure of the internal combustion engine.

According to a preferred development, the instantaneous pressure of the fluid, the instantaneous engine speed and / or the instantaneous compression ratio can be detected by sensors, in particular pressure sensors.

According to a preferred embodiment, the changeover valve is in a non-operating state in a predetermined switching position, d. H. either the first shift position or the second shift position, relocated.

According to a preferred development, the switching valve has a fluid groove for establishing the fluid connection of the first or second working space with the volume. This advantageously allows a simple production of the changeover valve and at the same time a simple switching from the first switching position to the second switching position.

According to a further preferred embodiment, the fluid groove is dimensioned such that a currently existing fluid connection of the first and second working space with the volume is maintained when the switching valve is in the third switching position. This advantageously enables an instantaneous or existing fluid connection to remain in the event of an imminent changeover from the first or second shift position to the second or first shift position until the predetermined shift position has actually been reached after the transition via the third shift position.

According to a further preferred development, a displacement of the switching valve in a respective switching position by an actuating pressure or switching pressure on the switching mechanism can be triggered. As a result, a displacement of the switching valve by the switching mechanism is executed executable. The terms "actuating pressure" and "switching pressure" are used synonymously herein.

According to a further preferred embodiment, the actuation pressure can be applied by a fluid pressure. As a result, the displacement of the switching valve by the switching mechanism in an easily controllable manner executable.

According to a further preferred refinement, in each case a specific fluid pressure can be applied to displace the switching valve into the first, the second and the third switching position. This allows a reliable and safe switching from the first to the second switching position and vice versa, whereby the reliability of the switching valve increases, since the switching depends on a certain predeterminable and controllable pressure value.

According to a further preferred embodiment, the switching mechanism is a ballpoint pen mechanism. The ballpoint pen mechanism is particularly advantageous because it can be produced in a particularly simple manner, and allows a safe and reliable switching.

According to a preferred embodiment, the switching mechanism is designed such that actuation of the switching valve takes place only at an actuating pressure above a predetermined threshold value. This reliably prevents accidental switching of the switching valve, thereby increasing its reliability.

According to a further preferred development, the changeover valve is integrated in the connecting rod arrangement, in particular in a region of the lifting bearing eye, whereby the changeover valve takes up only small installation space. As a result, the range of application of the changeover valve is advantageously extended.

According to a preferred embodiment, the actuation pressure can be applied by an engine oil pressure, the combustion engine having means, for example a controllable oil pump or a pressure accumulator or an additional oil pump, for briefly increasing the engine oil pressure. This advantageously makes it possible to integrate the changeover valve into existing engine oil systems, thereby widening the range of use of the changeover valve.

According to a preferred refinement, the changeover valve is additionally displaced into the first and / or the second shift position as a function of a current engine rotational speed and / or a current compression ratio of the internal combustion engine.

According to a preferred development, by a step of detecting the instantaneous pressure of the fluid, the instantaneous engine speed and / or the momentary Compression ratio detected by sensors, in particular pressure sensors.

According to a preferred embodiment, the displacement of the switching valve is in a non-operating state in a predetermined switching position, d. H. either the first shift position or the second shift position.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the attached schematic figures of the drawings.

From the figures shows:

1 Cross-sectional views of a connecting rod-piston assembly with a switching valve according to a preferred embodiment of the present invention in various operating conditions;

2 a detailed view of the connecting rod-piston assembly in an in 1 shown operating state;

3 a detailed view of a switching valve of the connecting rod-piston assembly 1 the preferred embodiment of the present invention;

4 a further detail of the switching valve of the preferred embodiment of the present invention according to the 3 ;

5a the switching valve of the preferred embodiment of the present invention according to 3 in a first switching position;

5b the switching valve of the preferred embodiment of the present invention according to 3 in a second switching position;

5c the switching valve of the preferred embodiment of the present invention according to 3 in a third switching position;

6a an engine load / speed shift diagram for the changeover valve of the preferred embodiment of the present invention;

6b an oil pressure / speed shift diagram for the switching valve of the preferred embodiment of the present invention;

7 a block diagram for explaining a control of the switching valve of the preferred embodiment of the present invention;

8a an engine load / speed shift diagram for the switching valve of another preferred embodiment of the present invention;

8b an oil pressure / speed shift diagram for the switching valve of the further preferred embodiment of the present invention; and

9 a block diagram for explaining a control of the switching valve of the further preferred embodiment of the present invention.

In the figures of the drawings, the same reference numerals designate the same or functionally identical components, unless indicated otherwise.

1 shows for a change-over valve according to the invention a connecting rod-piston arrangement 10 in two operating states A and B, wherein in operating state B, the connecting rod-piston assembly 10 is shown only partially to illustrate the essential difference between operating state A and B.

For better clarity, an inventive switching valve is initially omitted here. The connecting rod-piston arrangement 10 consists of a connecting rod 20 with a crank eye 30 , With the connecting rod 20 is a piston 40 coupled, which about a center axis 45 a connecting rod bearing eye 46 is pivotable, but in an eccentric manner, since a midpoint axis 50 a piston pin bore 60 of the piston 40 from the midpoint axis 45 of the connecting rod bearing eye 46 is spaced. By an eccentric device 65 with an eccentric body 70 and on the eccentric body 70 hinged eccentric rods 80 and 90 can be a position of the piston 40 relative to the connecting rod 20 be changed so as to produce a higher or lower compression as needed.

The operation of the eccentric rods 80 . 90 will be below with reference to 2 explained. However, in 1 to recognize that depending on a position of the eccentric rods 80 . 90 in the designated A operating state of the piston 40 relative to the connecting rod 20 protrudes further, and thus a compression is maximum, and in B designated operating state of the piston 40 relative to the connecting rod 20 is closer, and thus a compression is minimal.

In 2 is the connecting rod 20 shown in cross section, in turn, the Hublagerauge 30 , the connecting rod eye 46 with its midpoint axis 45 , the eccentric body 70 and the eccentric rods hinged thereto 80 and 90 can be seen. The eccentric rods 80 . 90 are with pistons 81 respectively. 91 in a first workroom 82 or in a second workspace 92 feasible. The workrooms 82 . 92 can via hydraulic lines 85 . 95 be filled with a fluid, such as engine oil, alternately, so that when one of the working spaces 82 . 92 is acted upon by fluid, the piston located therein 81 respectively. 91 is displaced accordingly, and thus eccentric rod 80 respectively. 90 the eccentric body 70 pivoted, which has a change in the piston position relative to the connecting rod and thus a changed compression result.

Im in 2 example shown is workspace 92 subjected to fluid while working space 82 is empty.

The in 2 shown state corresponds to the state B in 1 because an effective length l _eff between a midpoint axis 100 of the stroke bearing eye 30 and the midpoint axis 50 the (not shown here) piston pin bore is minimal.

So that an alternating filling of the work spaces 82 respectively. 92 can be done is a switching valve 110 provided, which in 2 is shown only schematically, and in detail with reference to 3 should be explained.

In principle, the change-over valve ensures 110 for being the first workroom 81 via a fluid line 86 or the second workspace 92 via a fluid line 96 alternatively with one volume 120 which, for example, the engine compartment (ie crankshaft housing) and / or the stroke bearing of the Hubagerauges 30 corresponds, is brought into fluid communication. That is, the changeover valve 110 can, as in 2 is shown, the fluid line 96 lock, leaving the work space 92 with fluid through the fluid line 95 is fillable. At the same time, the fluid line 86 of the workroom 82 via the changeover valve 110 open so that over the fluid line 85 in the workroom 82 flowing fluid again via a vent hole not shown in the volume 120 can escape, being the volume 120 the engine compartment or the stroke bearing or both can be. Thus, in the first working space 82 do not apply pressure to the eccentric rod 80 to move. As a corresponding vent hole for the second working space 92 through the switching valve 110 Locked, this can be done via fluid line 95 Incoming fluid does not escape, and it builds a pressure in the second working space 92 on which the eccentric rod 90 can shift, and thus the eccentric body 70 pivoted with the coupled thereto (not shown here) piston.

By a in 2 shown arrow I is indicated that an operating pressure must be applied to the switching valve, so that the switching valve 110 moves from one switch position to another, so corresponding to a fluid connection of the work spaces 82 . 92 with the volume 120 or not.

3 shows a detailed view of the switching valve 110 out 2 , It should be noted that the better representability because of in 3 shown switching valve 110 by 90 ° with respect to the representation of in 2 shown switching valve 110 is turned.

The changeover valve 110 sits in a valve block 130 of in 2 shown connecting rod 20 , and is in a valve hole 140 to the right and left, based on the 3 , relocatable. The changeover valve 110 includes a control mechanism 150 , consisting of actuating means or plunger 160 , Control sleeve 170 and torsion sleeve 180 , The control mechanism 150 works in the manner of a ballpoint pen mechanism, whose basic functional details will not be discussed here in more detail, since these are already described in detail elsewhere, among others by the applicant. Of course, other control mechanisms are conceivable besides a ballpoint pen mechanism.

Furthermore, the changeover valve comprises 110 a control piston 190 , which with the control mechanism 150 coupled at one end. At the other end of the spool 190 there is a spring device 200 which the control piston 190 biases. Around the spool 190 runs a fluid groove 210 , which depending on the switching position of the switching valve 110 with fluid lines 96 . 96 ' respectively. 86 . 86 ' can be brought into fluid communication. Here are the fluid lines 86 . 96 in the 2 shown fluid lines 86 . 96 , and the fluid lines 86 ' and 96 ' are the above-mentioned, but not previously shown vent holes to the engine interior and / or lifting bearings out. This in 3 Example shown thus shows the in 2 shown state where the first working space 82 with fluid line 86 through the switching valve 110 in fluid communication with the engine compartment or volume 120 stands, via vent hole or fluid line 86 ' , In this switching position of the changeover valve 110 is the fluid line 96 through the control piston 190 locked accordingly, the second working space 92 in 2 is not in fluid communication with the volume 120 and therefore can be pressurized with fluid while the first working space 82 (please refer 2 ) is depressurized or reduced pressure.

In 4 is the changeover valve 110 from his leadership, ie valve bore, shown detached, in relation to 3 in another switching position. This is to be recognized by the fact that the control sleeve 170 opposite the 3 is in a different position. This is, according to a presupposed as known ballpoint pen mechanism, a toothed ring surface 220 of the printing stamp 160 as well as torsion sleeve ribs 230 the torsion sleeve 180 to recognize.

As in 3 and 4 indicated with an arrow marked I (see also 2 ), by an actuating pressure I for displacing the switching valve 110 exerted a pressure in a switching position, as will be explained in more detail below.

According to such a ballpoint pen mechanism, a first and a second switching position can be generated, wherein a third switching position is assumed for a transition from the first switching position to the second switching position and vice versa. This should now be related to 5a to 5c be explained in more detail.

In 5a is the changeover valve 110 with the spring device 200 shown schematically in a first switching position. Here is the (not shown here) second working space 96 with fluid line 96 depressurized or reduced pressure, because of fluid groove 210 and fluid line 96 ' (Vent hole) is a fluid connection to the engine compartment. The fluid connection is in the 5a characterized by a continuous shaded strip. Accordingly, the first work space 82 (not shown here) not in fluid communication with the engine interior, and thus switched to pressure, since the control piston 190 a fluid connection between fluid line 86 and fluid line 86 ' in derogation.

In 5b is the changeover valve 110 in a second switching position, wherein now the (not shown here) first working space 86 with fluid line 86 is depressurized because of fluid line 86 ' (Vent hole) is a fluid connection to the engine compartment. The fluid connection is in the 5b characterized by a continuous shaded strip. The second workspace is correspondingly the same 92 (not shown here) not in fluid communication with the engine interior, and thus switched to pressure, since the control piston 190 a fluid connection between fluid line 96 and fluid line 96 ' in derogation.

A transition from the in 5a shown first switching position in the in 5b shown second switching position via an in 5c shown third switching position. Starting from the first switching position in 5a where the second workroom 92 (in 5c not shown) is depressurized, acts on the plunger 160 an actuating pressure Ip3 with a pressure value p3, so that the control piston 190 against the force of the spring device 200 in the 5c is pressed to the left. This is on the one hand compared to the spring device 200 in 5a more compressed spring device 200 in 5c to recognize, on the other hand, that the plunger 160 due to the operation of the ballpoint pen mechanism 150 to the control sleeve 170 encounters. Decisive in this third shift position is now that, starting from the first shift position in 5a , Furthermore, there is a fluid connection of the second working space to the engine interior, so that the second working space remains depressurized during the third switching position. Only when the pressure value of the actuating pressure I is changed from p3 to a smaller pressure value p2, as in 5b is indicated by an arrow designated lp2 arrow, the changeover valve shifts 110 from the in 5c shown third switch position in the in 5b shown second switching position. In this second switching position is in 5b to realize that the spring device 200 in relation to 5c is relaxed, and the control sleeve 170 no longer to the plunger 160 but rather to the control piston 190 , what by the presupposed as known effect of the ballpoint pen mechanism 150 comes about.

The remaining of the depressurized state during the third switching position is achieved, for example, by a dimensioning of the fluid groove 210 such that even with a shift of the switching valve 110 from the first switching position ( 5a ) in the third switching position ( 5c ), what in the 5a and 5c a slight shift of the switching valve 110 to the left corresponds to the fluid groove 210 still the fluid line 96 faces for a fluid connection. The same applies of course to the displacement of the second switching position ( 5b ) in the third switching position.

Analogously, a transition takes place back from the in 5b shown second switching position in the in 5a shown first switching position, again on the in 5c shown third switching position. That is, it acts, starting from the second switching position with a on the plunger 160 acting actuating pressure with pressure value p2, first an actuating pressure with pressure value p3 ( 5c ) until the pressure value of the operating pressure I is changed to p1 ( 5a ), so that the switching valve 110 in the first switching position ( 5a ) passes over.

The fact that during a transition from one switching position (first or second) to the other switching position (second or first), the respective currently depressurized working space during the third switching position, which may also be referred to as Aktuierungsphase, remains depressurized, is therefore advantageous, since in both situations (first shift position -> second shift position and vice versa) a relatively low compression guaranteed, and it can not come to an undesirable relatively high compression, which could lead to engine damage in the worst case. Therefore, such a function, ie the transition through the Aktuierungsphase, also referred to as fail-safe or emergency function, since a prevailing in the engine compartment supply oil pressure now permanently over Schaltöldrücke, ie pressure values p1, p2, p3, can be placed.

As an explanation, the following figures are intended to serve supplementary.

6a shows an example of an engine load / speed diagram in which map areas for compression ratios ε for low compression (ε = low) and high compression (ε = high) are plotted. The compression ratio ε results from the quotient of (displacement + compression space) and compression space. A solid line curve a represents the maximum threshold for engine load _versus speed. A dashed line curve p _me1 indicates an effective average engine load resulting from the effective mean engine pressure in the engine compartment, multiplied by the displacement of the engine. Above this curve p _me1 is a map with ε = low, and below the curve pme1 is a map with ε = high. Ie. in a speed range from about 1000 revolutions / min up to a speed threshold n2 at slightly less than 4000 revolutions / min is switched depending on the engine load either - at higher engine load - in the map with low compression (ε = low) or - at lower Engine load - in the map with high compression (ε = high), ie the changeover valve is switched accordingly.

For the speed range from n2 can be switched in a first variant - depending on the engine load - either in a map with low compression (ε = low) or in a map with high compression (ε = high), the two maps in 6a are separated from each other by a predefinable engine load switching threshold M. In a second variant, the speed range from n2 can also have only one characteristic map with low compression (ε = low), so that the compression there is always low.

According to shows 6b Oil pressure curves of the engine as a function of the speed. A curve b shows the oil pressure curve for a not yet warm engine, and a curve c shows the oil pressure curve for the engine at elevated operating temperature. With p _motor is a pressure level (dash-dotted line) for maximum engine oil pressure called, which results at maximum speeds. In order to bring now in the speed range below the speed threshold n2, the switching valve in one or the other switching position, depending on the in 6a shown maps, a pressure level with a pressure value p1, p2 or p3 is respectively generated in the engine interior for a short time, for example by a controllable auxiliary pump and / or a pressure accumulator. These pressures p1, p2, p3 respectively correspond to the actuation pressures Ip1, Ip2, Ip3 in FIGS 5a . 5b . 5c ,

In a first variant according to 6b the pressures p1 and p2 are below the pressure level P _motor , but above the "normal" engine _oil pressure p _oil in the speed range to n2, represented by the curves b and c in this speed range. Thus, inadvertent switching of the changeover valve is avoided by the "normal" engine oil pressure.

The pressure p3 is above the pressure level p _motor , so that switching of the switching valve is activated only by the pressure p3 or greater.

A curve p shows a possible _switching circuit pressure level, and a curve pmax denotes a maximum producible by the pump in the engine oil pressure level.

Based on 7 Now, a control of the switching valve based on the in 6b illustrated conditions explained.

In one step 100 Environment variables or values of environment variables of the switching valve are detected, such. B. an instantaneous speed n, an oil pressure p _oil and a compression ratio ε. The oil pressure p _oil is essentially a function of speed, temperature prevailing in the engine and effective mean pressure p _me .

In one step 200 a decision is made as to whether the detected value for the rotational speed n is smaller than a rotational speed threshold n2 or greater than or equal to the rotational speed threshold n2. In the first case, the control branches to step 300 , ie, n <n2, and in the second case, control branches to step 400 , ie n ≥ n2.

It then finds, ie after steps 300 respectively. 400 , in each case a query with respect to the compression ratio ε instead (step 500 or step 700 ).

First, the first case from step 500 be followed up. If the compression ratio ε is low (ε = low, shift position 1), the method branches to step 510 , If the compression ratio ε is high (ε = high, shift position 2), the method branches to step 610 ,

Starting from step 510 gets in one step 520 the value for the detected effective mean pressure p _me compared to a threshold P _me1 . If p _{me is} greater than or equal to p _me1 , the control points to step 530 , for p _me less p _me1 to step 540 , Starting from step 540 takes place in step 550 the command to control the change-over valve with the command "Switch position 2" (step 560 ), so that the compaction in one step 565 is set to ε = low.

Starting from step 530 takes place in step 535 the command not to control the switching valve, wherein in step 545 is displayed that "position 1" is present, and the compression ε remains in step 555 on ε = low.

Starting from step 610 gets in one step 520 the value for the detected effective mean pressure p _me compared with the threshold value p _me1 . P _me is greater than or equal p _me1, verzeigt control proceeds to step 630 , for p _me less p _me1 to step 640 , Starting from step 630 takes place in step 635 the command to control the change-over valve with the command "Switch position 1" (step 645 ), so that the compaction in one step 655 is set to ε = low.

Starting from step 640 takes place in step 650 the command not to control the switching valve, wherein in step 660 is displayed that "position 2" is present, and the compression ε remains in step 665 on ε = low.

The control proceeds analogously from step 400 :
If the compression ratio ε is low (ε = low, shift position 1), the method branches to step 710 , If the compression ratio ε is high (ε = high, shift position 2), the method branches to step 810 ,

Starting from step 710 takes place in step 720 the command not to control the switching valve, wherein in step 730 is displayed that "position 1" is present, and the compression ε remains in step 740 on ε = low. Starting from step 810 takes place in step 820 the command to control the change-over valve with the command "Switch position 1" (step 830 ), so that the compaction in one step 840 is set to ε = low.

After the steps 555 . 565 . 655 . 665 . 740 . 840 the controller branches again to step 100 ,

A second variant should now according to 8a and 8b be explained.

Here corresponds to the 8a essentially the 6a , so that is referred to the above.

According to 8b However, the pressures p1 and p2 and p3 are all below the pressure level p _motor , so as to further reduce an oil pressure requirement for switching, so that an engine oil pump can be designed to be relatively small. If a speed threshold n1 or an engine oil pressure greater than p3 is exceeded, the changeover valve is switched to the state ε = low even without active activation.

Based on 9 Now, a control of the switching valve based on the in 8b illustrated conditions, wherein the in 9 shown block diagram substantially the in 7 shown, and here only the differences should be discussed.

Starting from step 200 gets in one step 210 determined that the detected speed n is greater than or equal to a speed threshold n1, and thus that the third switching position of the changeover valve ("shift position 3") is present. That's why in one step 220 No command is given to control the changeover valve, and it will be in the control in step 230 notes that switch position 3 still exists because p is _oil ≥ p3. Thereupon, in one step 240 a value of an auxiliary quantity ng is set to "true", and in one step 250 the value for the compression ratio ε is set to "low".

Also starting from step 200 if the detected speed n is in the speed range n1> n≥n2 (step 400 ), a query takes place as to whether the value of the auxiliary variable ng is "true" (step 410 ). If so, the controller branches to step 700 , and continues as described above.

If not, the control branches immediately to step 810 , ie ε = low or "switch position 2" is set. Starting from step 810 takes place in step 820 the command to control the change-over valve with the command "Switch position 1" (step 830 ). Then in step 835 the value of the auxiliary size ng is set unequal to "true", and the compression in one step 840 set to ε = low.

Thus, by means of the auxiliary variable ng, an unambiguous identification of the shift position 1 or 2 in the speed range n1> n ≥ n2 after falling below the speed threshold n1 is made possible.

After the steps 555 . 565 . 655 . 665 . 250 . 740 . 840 the controller branches again to step 100 ,

It should be noted that when the engine is switched off, the value for ε is always set to the same value, eg. B. ε = low, ie switching position 1, so that there is a clear state with respect to the switching position of the change-over valve for the control at a restart of the engine.

LIST OF REFERENCE NUMBERS

10

Connecting rod-piston arrangement

20

pleuel

30

Hublagerauge

40

piston

45

Center point pin rod eye

46

Pleuellagerauge

50

Center point of the piston pin bore

60

Piston pin bore

65

eccentric

70

eccentric

80

eccentric

81

piston

82

first working space

85

fluid line

86

fluid line

86 '

vent hole

90

eccentric

91

piston

92

second workspace

95

fluid line

96

fluid line

96 '

vent hole

100

Center point axle bearing eye

110

switching valve

120

Volume / engine compartment

130

manifold

140

valve bore

150

control mechanism

160

plunger

170

control sleeve

180

Verdrehhülse

190

spool

200

spring means

210

fluid groove

220

toothed ring surface

230

Verdrehhülsenrippen

Ip1

actuating pressure

Ip2

actuating pressure

Ip3

actuating pressure

a, b, c

curves

n ₂

Speed threshold

p _engine

pressure level

p is _switching

pressure level

p _max

pressure level

p1, p2, p3

pressures

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005055199 [0004]

Claims (19)

Changeover valve ( 110 ) for controlling a fluid flow in an internal combustion engine, with a switching mechanism ( 150 ), which is adapted to the switching valve ( 110 ) in each case by a predetermined actuating pressure to shift into a first switching position and a second switching position, whereby in each case a first working space or a second working space ( 82 . 92 ) with a volume ( 120 ) can be brought into fluid communication, wherein a shift into the first and / or the second switching position takes place in dependence on an oil pressure in the internal combustion engine. Changeover valve ( 110 ) according to claim 1, characterized in that for a transition from one switching position to the other, the switching valve ( 110 ) is displaceable in a third switching position, in which a momentarily in fluid communication with the volume ( 120 ) standing working space remains in this fluid connection, until the other switching position is reached. Changeover valve ( 110 ) according to claim 1 or 2, characterized in that the displacement into the first and / or the second switching position additionally takes place as a function of a current engine speed and / or a current compression ratio and / or an engine load and / or a mean engine oil pressure of the internal combustion engine. Changeover valve ( 110 ) according to claim 2, characterized in that the instantaneous pressure of the fluid, the instantaneous engine speed and / or the instantaneous compression ratio can be detected by sensors, in particular pressure sensors. Changeover valve ( 110 ) according to one of claims 1 to 4, characterized in that the switching valve ( 110 ) is shifted in a non-operating state in either the first shift position or the second shift position. Changeover valve ( 110 ) according to one of the preceding claims, characterized in that the switching valve ( 110 ) a fluid groove ( 210 ) for establishing the fluid connection of the first and second working space ( 82 . 92 ) with the volume ( 120 ) having. Changeover valve ( 110 ) according to claim 6, characterized in that the fluid groove ( 210 ) is dimensioned such that a currently existing fluid connection of the first and second working space ( 82 . 92 ) with the volume ( 120 ) is maintained when the switching valve ( 110 ) is in the third switching position. Changeover valve ( 110 ) according to one of the preceding claims, characterized in that a displacement of the switching valve ( 110 ) in a respective switching position by an actuating pressure (I) on the switching mechanism ( 150 ) is triggered. Changeover valve ( 110 ) according to claim 8, characterized in that the actuating pressure (I) can be applied by a fluid pressure. Changeover valve ( 110 ) according to claim 9, characterized in that for displacing the switching valve ( 110 ) In each of the first, the second and the third switching position, a certain fluid pressure can be applied. Changeover valve ( 110 ) according to one of claims 8 to 10, characterized in that the switching mechanism ( 150 ) is designed such that an actuation of the switching valve ( 110 ) takes place only at an actuation pressure (I) above a predetermined threshold value. Changeover valve ( 110 ) according to one of the preceding claims, characterized in that the switching mechanism ( 150 ) is a ballpoint pen mechanism. An internal combustion engine having an adjustable compression ratio, comprising: a switching valve ( 110 ) according to any one of the preceding claims; and a connecting rod assembly ( 10 ) with one in a connecting rod eye ( 46 ) and / or a bung eye ( 30 ) arranged hydraulically adjustable eccentric ( 65 ) for adjusting an effective connecting rod length (l _eff ), wherein a displacement of the eccentric means by means of the switching valve ( 110 ) is controllable. Internal combustion engine according to claim 13, characterized in that the switching valve ( 110 ) in the connecting rod assembly ( 10 ), in particular in a region of the Hubagerauges ( 30 ) is integrated. Internal combustion engine according to claim 13 or 14, characterized in that the actuating pressure can be applied by an engine oil pressure, wherein the internal combustion engine having means, such as a controllable oil pump or a pressure accumulator for briefly increasing the engine oil pressure. Method for controlling a changeover valve ( 110 ) according to one of the preceding claims, the method comprising the following steps: detecting a momentary pressure of the fluid in the internal combustion engine; Comparing the detected instantaneous pressure with at least one predetermined pressure threshold; and controlling the switching valve ( 110 ) such that the switching valve ( 110 ) is shifted in response to the comparison in a first or second switching position. A method according to claim 16, characterized in that the switching valve ( 110 ) is additionally displaced in the first and / or the second shift position in dependence on a current engine speed and / or a current compression ratio of the internal combustion engine. A method according to claim 16 or 17, characterized in that by the step of detecting the instantaneous pressure of the fluid, the instantaneous engine speed and / or the instantaneous compression ratio are detected by sensors, in particular pressure sensors. Method according to one of Claims 16 to 18, characterized by a step of displacing the switching valve ( 110 ) from a non-operating state to either the first shift position or the second shift position.

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