DE102015203417B4 - switching valve - Google Patents

Abstract

A switching valve (27) for actuating a device for varying a compression ratio of a reciprocating internal combustion engine comprises a valve slide (28) which can be moved in two different switching positions and which is arranged longitudinally displaceably in a cylindrical receiving bore (30) and via a control chamber communicating with a control port (32) (33) at a first axially directed end face (34) is acted upon with at least two different hydraulic control pressures, at least one return spring (35), with the one of the first axially directed end face (34) facing away from the second axially directed end face (36) of the valve spool (28) can be acted upon by a restoring force, and at least one locking mechanism (37) with which the valve slide (28) can be locked in at least one of its switching positions. In order to provide a switching valve (27) with a novel locking mechanism (37), which makes a space-saving design of the switching valve (27) possible, it is proposed with the invention that the locking mechanism (37) is formed by at least one in the receiving bore (30). provided, axially acting latching recess (38), by at least one within a the control chamber (33) facing portion of the valve spool (28) arranged transverse bore (40), by at least one in the transverse bore (40) longitudinally displaceable locking pin (41, 42) between a locking position engaged in the latching recess (38) and a release position disengaged therefrom, and by at least one compression spring (43) arranged in the transverse bore (40), which pushes the locking bolt (41, 42) with a force in the direction of its locking position acted upon, by a maximum control pressure, first of the locking pin (41, 42) disengaged and the Valve slide (28) is moved from its first switching position against the force of the return spring (35) in its second switching position.

Description

Field of the invention

The invention relates to a switching valve for actuating a device for varying a compression ratio of a reciprocating internal combustion engine, comprising a movable in two different switching positions valve slide which is longitudinally displaceably arranged in a cylindrical receiving bore and communicating via a communicating connected to a control terminal control chamber at a first axially directed end face with at least two different hydraulic control pressures can be acted upon, at least one return spring with which a second axially directed end face facing away from the first axially directed end face of the valve spool is acted upon by a restoring force, and at least one locking mechanism with which the valve spool can be locked in at least one of its switching positions.

Furthermore, the invention relates to a connecting rod for a reciprocating internal combustion engine with adjustable compression ratio, which is adjustable in two stages to adjust the compression ratio in its effective length, comprising at least one adjusting device for adjusting the effective length of the connecting rod, which arranged at least one in a piston-side connecting rod eye of the connecting rod Eccentric, at least two acted upon by a hydraulic fluid hydraulic chambers, in each of which a control piston is slidably mounted, and at least two piston rods, each connecting an actuating piston with the eccentric having.

State of the art

With the compression ratio ε of a reciprocating internal combustion engine, the ratio of the volume of the entire cylinder chamber to the volume of the compression chamber is designated. By increasing the compression ratio of the efficiency of the reciprocating internal combustion engine can be increased, resulting in a total of a reduction in fuel consumption results in the same performance of the reciprocating internal combustion engine. However, it should be noted that in spark-ignited reciprocating internal combustion engines with an increase in the compression ratio in full load operation, the tendency to knock increases.

The knocking is an uncontrolled self-ignition of the fuel-air mixture. On the other hand, in the partial load operation in which the charge is lower, the compression ratio may be increased to improve the corresponding partial load efficiency without the aforementioned knocking occurring. As a result, it is expedient to operate the reciprocating internal combustion engine in part-load operation with a relatively high compression ratio and in full load operation with a reduced compression ratio compared to this.

A change in the compression ratio is also particularly advantageous for supercharged reciprocating internal combustion engines with spark ignition, as these overall in terms of charging a low compression ratio is given, and to improve the thermodynamic efficiency in unfavorable areas of a corresponding engine map, the compression is to increase. In addition, there is the possibility of generally changing the compression ratio as a function of further operating parameters of the reciprocating internal combustion engine, such. B. driving conditions of the motor vehicle, operating points of the internal combustion engine, signals of a knock sensor, exhaust emissions, etc.

Among other things, devices are known from the state of the art, in which the compression ratio is adjusted via an eccentric arranged within a connecting rod eye of the connecting rod. This eccentric is received on its outer circumferential surface of the connecting rod, while in a eccentric bore of the eccentric a piston pin receiving a piston pin bearing is arranged.

The corresponding eccentric is adjusted by the engine forces occurring in the cylinder unit between the connecting rod on the one hand and the piston pin or the crank pin on the other hand, ie load forces resulting from the mass and gas forces. In the working cycle of the cylinder unit, the acting forces change continuously. It is expedient to connect the eccentric with two actuating pistons, which attack on this to its rotation and support via tabs. Thus, the rotational movement supported by the two adjusting pistons and a provision of the eccentric, which can occur due to the forces transmitted to the eccentric with different directions of force, can be avoided. The rotational position of the respective eccentric is controlled via a switching valve, so that each cylinder unit of the reciprocating internal combustion engine is assigned in each case a switching valve, via which the compression ratio of the cylinder unit is set.

A switching valve for operating a device for varying a compression ratio of a reciprocating internal combustion engine of the type described in the preamble of claim 1 is known from DE 10 2013 103 685 A1 known. The adjusting device has one in one Connecting rod eye of a connecting rod arranged eccentric with an eccentric piston pin bore, wherein the eccentric is provided with diametrically extending tabs on which attack on eccentric rods piston. Pressure chambers, which are provided between the piston and guide rods formed in the connecting rod, are supplied with oil from a connecting rod bearing via oil lines, in each of which a non-return valve which prevents backflow. In addition to the respective oil line, a further fluid line is connected to each of the two pressure chambers, which leads to a switching valve.

The switching valve has a movable in two different switching positions valve spool. The valve spool is arranged longitudinally displaceably in a cylindrical receiving bore formed by a valve housing and can be acted upon by a control chamber communicating with a control port at a first axially directed end face with two different hydraulic control pressures. Furthermore, the switching valve comprises a return spring, with which a second axially directed end face of the valve slide facing away from the first axially directed end face can be acted upon by a restoring force. The valve spool rests against a switching device with an axially equal to the second axially directed surface. The switching device is designed as Sekurit ^TM -Mechanik, which is also referred to as ballpoint pen mechanism. About this switching device can be changed by appropriate pressure pulses to the first axially directed end face of the valve spool continuously whose switching positions.

By means of the switching device, the valve spool can be locked in both switching positions.

Another switching valve is out of the DE 10 2005 055 199 A1 known. The switching valve is designed as a switching valve and arranged in the vicinity of the small bearing eye of a connecting rod. The switching valve is designed as a 3/2-way valve and can be held by means of a latching mechanism in its first and the second switching position. A latching in one of the two switching positions is realized by means of a force acted upon by the force of a spring ball, which engages in a formed on the groove bottom of a control groove counter contour.

Another switching valve shows the DE 10 2010 016 037 A1 , In the disclosed embodiment, the locking takes place via a so-called ballpoint pen mechanism. By applying an actuating pulse to an actuating means, the ballpoint pen mechanism engages alternately in a first or in a second detent position. The ballpoint pen mechanism is coupled to the switching valve such that the first and the second detent position corresponds to a respective first or second switching position of a control piston of the switching valve.

Disclosure of the invention

The object of the invention is to provide a switching valve of the type mentioned with a novel locking mechanism, which makes a space-saving design of the switching valve possible.

This object is solved by the independent claims. Advantageous embodiments are given in the dependent claims, each of which taken alone or in various combinations with each other can represent an aspect of the invention.

The switching valve according to the invention for actuating a device for varying a compression ratio of a reciprocating internal combustion engine comprises a valve slide which can be moved in two different switching positions, which is arranged longitudinally displaceably in a cylindrical receiving bore and, via a control chamber communicating with a control port, at a first axially directed end face with at least two different hydraulic control pressures can be acted upon.

Furthermore, the switching valve has at least one return spring, with which a second axially directed end face of the valve slide facing away from the first axially directed end face can be acted upon by a restoring force. In addition, part of the switching valve is at least one locking mechanism with which the valve slide can be locked in at least one of its switching positions. In this case, the locking mechanism is formed by at least one provided in the receiving bore, acting in the axial direction of the valve slide, radially provided for this recess, by at least one within a control chamber facing portion of the valve spool arranged transverse bore, by at least one longitudinally displaceable in the transverse bore locking pin, the is movable between a latching position engaged in the latching recess and a release position disengaged therefrom, and by at least one pressure spring arranged in the transverse bore, which acts on the latching bolt with a force in the direction of its locking position. In this case, the locking pin is first disengaged by a maximum control pressure, and then the valve spool is moved from its first switching position against the force of the return spring in its second switching position.

According to the invention, the valve spool instead of a switching device according to the Switching valve according to DE 10 2013 103 685 A1 can be locked in at least one of its switching positions via a novel locking mechanism. In contrast to the elaborately designed switching device accordingly DE 10 2013 103 685 A1 are relatively few and space-saving components required to form the locking mechanism according to the invention, which is associated with a space-saving design of the switching valve according to the invention as a whole.

A provided in the receiving bore recess, which acts in the axial direction of the valve slide and is provided radially to this, means that the locking pin located in its locking position cooperates with the recess such that the valve slide is not out of its first switching position in the direction of its second switching position is longitudinally displaceable. Is moved by the maximum control pressure of the locking pin in its disengaged from the detent recess release position, the acting in the axial direction locking the valve spool is canceled so that it is then axially movable into its second switching position by the application of this maximum control pressure. For this purpose, it is necessary that the locking pin receiving the recess in the locking position of the locking pin is connected to the control chamber so that it is acted upon by the maximum control pressure and displaced by means of the maximum control pressure in the direction of its release position.

According to an advantageous embodiment, after a displacement of the valve spool in its second switching position, the maximum control pressure is reduced to a normal engine oil pressure, wherein the return spring is designed such that the force of the return spring is smaller than a force resulting from the normal engine oil pressure on the valve spool. As a result, the valve spool is reliably maintained in its second switching position in the presence of the normal engine oil pressure. The at least one locking pin is located in its against the force of the compression spring radially inward shifted position and thus is biased against the inner surface of the receiving bore, so that the friction occurring additionally prevents a provision of the valve spool in its first switching position, as long as the control pressure does not fall below a corresponding lower limit.

Advantageously, the valve spool for switching from the second switching position to the first switching position can be acted upon with a reset pressure which is lower than the normal engine oil pressure. By applying the reset pressure, the switching positions of the valve spool all switching valves of reciprocating internal combustion engine can be synchronized, if it has previously come to a malfunction of individual switching valves, in which the valve spool of at least one switching valve in the first switching position and the valve spool of at least one further switching valve in the second switching position is located. After applying the reset pressure, all valve spools are in their first switching positions.

In contrast, in the switching valve according to the DE 10 2013 103 685 A1 a provided at low engine speed reset function provided, are prevented in the first switching position located in switching valves from performing a switching movement. For this purpose, a return spring receiving receiving pressure medium filled spring chamber is blocked at its outlet by a centrifugal force actuated shut-off valve. The creation of a corresponding reset function is associated with a significant construction cost.

It is furthermore advantageous if, in the second switching position of the valve slide, a working connection is connected to the control connection. Thus, in this switching position, a connection between an oil return line of an adjusting device and a control line connected to the control line, which emanates from an oil gallery of the reciprocating internal combustion engine produced. The advantages of oil return from the oil return line to the control line and thus to the oil gallery are that the oil pump can be run with less power and the lubricating oil pressure in the oil gallery is not reduced to unfavorable levels by the lube oil flowing out into the oil pan.

According to a further advantageous embodiment, the receiving bore is formed by an arranged in a valve housing or a valve receiving bore of a component press-fit, wherein an end face of the press-fit serves as a side wall of the formed as a circumferential groove recess. As a result, the latching recess can be formed in a simple manner. The front side of the press-fit sleeve serves as an axial stop. Since the latching recess is formed as a circumferential groove, a locking of the valve slide in its first switching position can be carried out regardless of which angular position of the locking pin has taken over the latching recess.

A further advantageous embodiment provides that the locking mechanism has two longitudinally displaceable arranged in the transverse bore locking pin, which are biased by the compression spring in opposite directions, wherein in the transverse bore at least one stop is arranged, on which at least one locking pin rests in its release position in the axial direction. When applying the maximum control pressure, it is likely that the locking pins move not synchronously, but offset in time from their locking positions in their release positions. To prevent this, that a locking pin engages so far into the transverse bore, that the other locking pin can not be completely transferred to its release position, the stop is provided in the transverse bore on which each locking pin can rest axially in its release position. Alternatively, a separate stop can be provided in the transverse bore for each locking bolt. The stop may be formed as a constriction of the transverse bore through which the compression spring extends.

Advantageously, a remote from the compression spring end of the locking pin is formed crowned. This favors on the one hand the attacking of the maximum control pressure at a radially outer end portion of the locking bolt in order to be able to transfer it safely from its locking position into its release position. On the other hand, by the spherical formation of the end of the locking bolt of the locking bolt, after it has been moved by means of the maximum control pressure already slightly out of its locking position, are urged by a contact with a side wall of the locking support mechanically towards its release position, if the same time Valve spool is displaced under the action of the maximum control pressure in the direction of its second switching position.

It is also advantageous if the side wall of the latching recess forming end face of the press-in sleeve, starting from the inner circumferential surface, is provided with a chamfer. As a result, the locking bolt, after it has already been moved slightly out of its locking position by means of the maximum control pressure, are mechanically urged by contact with the chamfer in the direction of its release position, if at the same time the valve spool under the effect of the maximum control pressure in the direction of its second switching position is relocated.

Furthermore, the object is achieved in that the locking mechanism is formed by at least one provided in the receiving bore, acting in the axial direction of the valve spool, radially provided for this recess, by at least one transverse bore, which is disposed within a control chamber facing portion of the valve spool, by at least one longitudinally displaceable in the transverse bore locking bolt, which is movable between an engaged locking position, in which the first end engages in the latching recess, and a disengaged from this release position, and by at least one arranged in the transverse bore compression spring, which together with the on a Longitudinal bore of the valve spool supplied control pressure applied to the locking bolt at its second end in the direction of its locking position, that the locking recess is provided in its locking direction with a chamfering bevel and that by a n maximum control pressure of the valve slide is shifted from its first switching position against the force of the return spring in its second switching position, wherein the at least one locking pin is disengaged at the beginning of the displacement of the valve spool against the control pressure and the force of the compression spring. This alternative solution takes into account that the pressurization of the at least one locking bolt can not take place in such a way that it is displaced radially inwards at the beginning of the adjustment process, so that the locking mechanism comes into its release position.

Therefore, the locking recess in the reverse direction on a chamfer, which extends like a ramp and moves the locking piston mechanically in its release position. But so that the valve spool, which is loaded via the return spring with a comparatively small spring force is moved only with the increased control pressure from the locked first switching position in the second switching position acts on the second end of the at least one locking bolt in addition to the compression spring and this on a Longitudinal bore in the valve spool at the second end of the locking pin supplied control pressure. A release of the valve spool takes place only when the force generated via the chamfer is greater than that by the compression spring and the force generated at the cross section of the locking pin.

The connecting rod according to the invention for a reciprocating internal combustion engine with adjustable compression ratio is at least two stages adjustable to adjust the compression ratio in its effective length and comprises at least one adjusting device for adjusting the effective length of the connecting rod, the at least one arranged in a piston rod end of the connecting rod eccentric, at least two with a Hydraulic fluid acted upon hydraulic chambers, in each of which a control piston is slidably mounted, and at least two piston rods, each connecting an actuating piston with the eccentric, and at least one switching valve according to one of the aforementioned embodiments or any combination thereof. With the connecting rod, the advantages mentioned above with respect to the switching valve are connected accordingly.

The invention is not limited to the specified combination of the features of the independent Claims with the dependent claims limited. In addition, there are further possibilities of combining individual features, in particular if they result from the patent claims, the following description of the exemplary embodiment or directly from the figures. In addition, the reference of the claims to the figures by the use of reference numerals is not intended to limit the scope of the claims to the illustrated embodiment.

Short description of the drawing

To further explain the invention, reference is made to the figures, in which an embodiment of the invention is shown in simplified form. Show it:

1 a schematic representation of a consisting of a working piston and a connecting rod unit with an adjusting element, via which the position of the working piston relative to the connecting rod is variable on a piston pin;

2 a longitudinal section through an embodiment of an inventive switching valve, which within the receiving bore of in 1 arranged connecting rod is arranged, when applying a reset pressure;

3 a longitudinal section through the in 2 shown switching valve with befindlichem in its first switching position valve spool and in case of normal engine oil pressure;

4 a longitudinal section through the in the 2 and 3 shown switching valve upon application of the maximum control pressure in a first transition state in which one of the locking pin is displaced radially inward;

5 a longitudinal section through the in the 2 to 4 shown switching valve with located in its second switching position valve spool and concerns of the maximum control pressure;

6 a longitudinal section through the in the 2 to 5 shown switching valve when concerns the reset pressure;

7 a longitudinal section through the in the 2 to 6 shown switching valve with befindlichem in its first switching position valve spool and in case of normal engine oil pressure;

8th a longitudinal section through a further embodiment of an inventive switching valve, which within the receiving bore of in 1 arranged connecting rod is arranged, with befindlichem in its first switching position valve spool and in case of normal engine oil pressure;

9 a pressure diagram, the different control pressures in the switching positions and during the individual switching operations of the valve spool can be removed.

Detailed description of the drawing

In the 1 is with 1 a connecting rod for a cylinder unit of a reciprocating internal combustion engine referred to, which consists of a part as a connecting rod shank 2a trained connecting rod upper part 2 and a connecting rod base 3 consists. The connecting rod upper part 2 and the connecting rod base 3 together form a connecting rod eye 4 that is a longitudinal center axis 4a and over which the connecting rod 1 is mounted on a crank pin, not shown, a crankshaft. At its other end is the connecting rod top 2 with a connecting rod eye 5 provided, in which about as eccentric 6 trained adjustment 7 and a not-shown piston pin bearing a piston pin 8th is arranged. About this rotatably guided in the piston pin bearing piston pin 8th is a working piston 9 a cylinder unit of the reciprocating internal combustion engine to the adjusting element 7 the rotation of which leads in one direction to set a relatively low compression ratio and its rotation in the opposite direction to set a higher compression ratio.

The eccentric 6 is characterized by in the cylinder unit between the connecting rod 1 on the one hand and the piston pin 8th or the crank pin on the other hand occurring engine forces, ie mass and load forces adjusted. In the working cycle of the cylinder unit, the acting forces change continuously. The eccentric 6 has diametrically extending tabs 10 and 11 on, each via piston rods 12 and 13 with single-acting actuator piston 14 and 15 are connected. The adjusting pistons 14 and 15 grip on the aforementioned components on the eccentric 6 to twist and support it. Thus, by the adjusting piston 14 and 15 the rotational movement of the eccentric 6 supports and its provision, due to different directions of force on the eccentric 6 transmitted forces would be avoided avoided.

The adjusting pistons 14 and 15 are in support cylinders 16 and 17 guided and together with these pressure chambers 18 and 19 in which serving as a hydraulic medium lubricating oil of the reciprocating internal combustion engine from a in the connecting rod eye 4 arranged connecting rod bearings 20 via oil supply lines 21 and 22 can flow in. Furthermore, it goes from each of the pressure chambers 18 and 19 an oil return line 23 respectively. 24 from, like, from the 1 emerges, both in a valve receiving bore 25 for a switching valve described in connection with the other figures. This valve receiving bore 25 runs inside the connecting rod shaft 2a , transverse to this, that is parallel to the longitudinal central axis 4a of the connecting rod bearing eye 4 , From the connecting rod bearing 20 also performs a fluid line 26 to the valve receiving bore 25 ,

In the 2 to 7 are the different switching states of a switching valve according to the invention 27 shown. This switching valve 27 should inside the valve receiving bore 25 of in 1 shown connecting rod 1 be arranged., In the 2 , which will be explained below for explaining the structure of the switching valve 27 should serve, this is acted upon by a reset pressure, which is for example 1.8 bar. In through the connecting rod shaft 2a formed valve receiving bore 25 is a stopper 29 arranged, with which the valve receiving bore 25 closed on one side. The valve spool 28 is due to reset pressure on the plug 29 at.

The switching valve 27 is to selectively control the two positions of in 1 shown adjustment of the connecting rod 1 intended. Consequently, the switching valve 27 with the leading to the support cylinders oil return lines 23 and 24 and with the outgoing from the interior of the connecting rod bearing eye fluid line 26 connected. Serving as a control pressure means engine oil is by means of a variable displacement pump, not shown in the lubricating oil circuit of the reciprocating internal combustion engine and thus via corresponding oil galleries in the plain bearing of the connecting rod bearing eye 4 from where it flows into the fluid line 26 and via check valves in the oil supply lines 21 and 22 arrives.

The valve spool 28 is movable in two different switching positions and in a cylindrical receiving bore 30 arranged longitudinally displaceable, by a in the valve receiving bore 25 arranged injection sleeve 31 is formed. Furthermore, the valve spool 28 via one with a control connection 32 communicatively connected control room 33 on a first axially directed end face 34 can be acted upon by three different hydraulic control pressures. In addition, the press-fit sleeve 31 working lines 32a and 32b on, to the oil return lines 23 and 24 according to 1 are connected. The switching valve 27 includes a return spring 35 with one of the first axially directed end face 34 remote second axially directed end face 36 of the valve spool 28 can be acted upon by a restoring force. As a result, when the Resetdruck concerns the valve slide 28 against the stopper 29 pressed. The return spring 35 supports itself with one end to one within the press-fit sleeve 31 arranged lid 45 from.

Furthermore, the switching valve comprises 27 a locking mechanism 37 with which the valve slide 28 in his in 3 shown first switch position is locked. The locking mechanism 37 includes one in the receiving bore 30 provided axially acting recess 38 where one end face 39 the press-fit sleeve 31 as a side wall of the formed as a circumferential groove recess 38 serves. The locking mechanism 37 further includes one within a control room 33 facing portion of the valve spool 28 arranged transverse bore 40 and two longitudinally displaceable in the transverse bore 40 arranged locking bolt 41 and 42 , Each locking pin 41 respectively. 42 is between the shown, in the recess 38 engaged locking position and one in the 5 shown, from the recess 38 moved release position movable. Furthermore, the locking mechanism comprises 37 one in the cross hole 40 arranged compression spring 43 , by means of the locking bolts 41 and 42 are biased in opposite directions. In particular, each locking pin 41 respectively. 42 by means of the compression spring 43 acted upon by a force in the direction of its locking position.

In the cross hole 40 are due to a narrowing of the transverse bore 40 trained attacks 44 and 44a arranged at which locking bolt 41 , respectively. 42 can rest axially in their release position, as in the 5 to 7 is shown. That of the compression spring 43 opposite end of each locking bolt 41 respectively. 42 is spherical. By a maximum control pressure, the locking bolts are first 41 and 42 from the recess 38 disengaged and the valve spool 28 from its first switching position against the force of the return spring 35 moved to its second switching position, as it is from the 4 to 6 becomes clear.

3 shows a position of the valve spool 28 that it occupies at one in its first shift position and when the normal engine oil pressure is higher than the reset pressure and may be about 2-5 bar. As a result, the locking bolts are 41 and 42 at the front 39 the press-fit sleeve 31 at. This is the valve spool 28 locked in its first switching position.

4 shows the switching valve 27 when concerns the maximum control pressure, which may be, for example, 6 bar, this is the locking pin 42 against the force of the compression spring 43 was moved from its locking position in the direction of its release position, while the locking pin 41 still in its locked position.

5 shows the switching valve 27 with located in its second switching position valve slide 28 into this, after both locking bolts 41 and 42 moved into their release position, against the force of the return spring 35 has been moved. until reaching the second switching position, the maximum control pressure prevails with, for example, 6 bar. After reaching the second switching position, the control pressure is reduced again to the normal engine oil pressure with, for example, 2 to 5 bar. The return spring 35 is designed so that, contrary to said engine oil pressure no adjustment of the valve spool 28 takes place, so this remains in the second switching position.

Now, if the control pressure to the reset pressure, so for example 1.8 bar reduced, the valve spool moves back to the position according to the 6 and lies with his front page 34 at the stopper 39 at. The locking bolts 41 and 42 are back in their locking positions, in which they are in the recess 38 intervention.

7 shows the switching valve 27 with located in its first switching position valve spool 28 and in case of concern the normal engine oil pressure, so z. B. 2 to 5 bar. The locking bolts 41 and 42 are still at the front 39 the press-fit sleeve 31 on, causing the locking of the valve spool 28 he follows.

8th shows a longitudinal section through a further embodiment of a switching valve according to the invention 27 That inside the valve receiving bore 25 of in 1 shown connecting rod 1 can be arranged with located in its first switching position valve spool 28 and in case of normal engine oil pressure. This representation corresponds to the representations of 3 and 7 , This embodiment differs from that in the 2 to 7 shown embodiment that the side wall of the recess 38 forming front side 39 the press-fit sleeve 31 , starting from its inner circumferential surface 47 the receiving bore 30 , with a chamfer 46 is provided. This chamfering 46 runs ramp-like and moves the two locking pistons 41 and 42 mechanically in its release position by cooperating with the first ends. As already stated, the valve spool 28 that's about the return spring 35 is loaded with a comparatively small spring force, moved only with the increased control pressure from the locked first switching position in the second switching position. For this reason, it is provided that on the second ends of the locking bolt 41 and 42 next to the compression spring 43 also the one over a longitudinal bore 48 in the valve spool 28 acting on the second ends of the locking pin control pressure acts, which causes a force amplification. A release of the valve spool 28 takes place only when the over the chamfering 46 generated force is greater than that by the compression spring 43 and at the cross section of the respective locking bolt 41 respectively. 42 generated force.

In the 9 is shown by a solid line, the pressure curve of the control pressure. In a first area a is the switching valve 27 in its first switching position, wherein the control pressure in the range of the operating pressure, ie the normal engine oil pressure moves. In the area b, the control pressure initially rises briefly to the maximum value, and then reduced again to the operating pressure. In area c, the control pressure is briefly reduced to the reset pressure, so that the switching valve 27 gets into its first sleeping position, in which area the control pressure is increased again to the operating pressure.

LIST OF REFERENCE NUMBERS

1

pleuel

2

Pleueloberteil

2a

connecting rod shaft

3

Pleuelunterteil

4

Pleuellagerauge

4a

Longitudinal central axis of 4

5

connecting rod

6

eccentric

7

adjustment

8th

piston pin

9

working piston

10

flap

11

flap

12

piston rod

13

piston rod

14

actuating piston

15

actuating piston

16

supporting cylinders

17

supporting cylinders

18

pressure chamber

19

pressure chamber

20

connecting rod bearing

21

Oil supply line

22

Oil supply line

23

Oil return line

24

Oil return line

25

location hole

26

fluid line

27

switching valve

28

valve slide

29

Plug

30

location hole

31

Press-

32

control connection

32a

working port

32b

working port

33

control room

34

face

35

Return spring

36

face

37

locking mechanism

38

recess

39

front

40

cross hole

41

locking pin

42

locking pin

43

compression spring

44

attack

45

cover

46

chamfer

47

Inner lateral surface of 31

48

Longitudinal bore in 28

Claims (10)

Switching valve ( 27 ) for actuating a device for varying a compression ratio of a reciprocating internal combustion engine, comprising a valve slide which can be moved into two different switching positions (US Pat. 28 ), which in a cylindrical receiving bore ( 30 ) arranged longitudinally displaceable and via a with a control terminal ( 32 ) communicating control room ( 33 ) at a first axially directed end face ( 34 ) can be acted upon with at least two different hydraulic control pressures, at least one return spring ( 35 ), with one of the first axially directed end face ( 34 ) facing away from the second axially directed end face ( 36 ) of the valve spool ( 28 ) is acted upon by a restoring force, and at least one locking mechanism ( 37 ), with which the valve slide ( 28 ) is lockable in at least one of its switching positions, characterized in that the locking mechanism ( 37 ) is formed by at least one in the receiving bore ( 30 ), in the axial direction of the valve spool ( 28 ) acting, radially provided for this recess ( 38 ) by at least one within a control room ( 33 ) facing portion of the valve spool ( 28 ) arranged transverse bore ( 40 ), by at least one in the transverse bore ( 40 ) longitudinally displaceable locking bolt ( 41 . 42 ), which between one in the recess ( 38 ) engaged locking position and a disengaged from this release position is movable, and by at least one in the transverse bore ( 40 ) arranged compression spring ( 43 ), which the locking bolt ( 41 . 42 ) acted upon by a force in the direction of its locking position, wherein by a maximum control pressure of the first locking bolt ( 41 . 42 ) and then the valve slide ( 28 ) from its first switching position against the force of the return spring ( 35 ) is moved to its second switching position. Switching valve ( 27 ) according to claim 1, characterized in that after a displacement of the valve spool ( 28 ) is reduced to its second switching position, the maximum control pressure to a normal engine oil pressure, wherein the return spring ( 35 ) is designed such that the force of the return spring ( 35 ) is smaller than the force resulting from the normal engine oil pressure at the valve spool ( 28 ). Switching valve ( 27 ) according to claim 2, characterized in that the valve spool ( 28 ) can be acted upon for switching from the second switching position to the first switching position with a reset pressure which is less than the normal engine oil pressure. Switching valve ( 27 ) according to claim 3, characterized in that in the second switching position of the valve spool ( 28 ) a work connection ( 32a ) with the control connection ( 32 ) connected is. Switching valve ( 27 ) according to one of claims 1 to 4, characterized in that the receiving bore ( 30 ) by a arranged in a valve housing or a valve receiving bore of a component injection sleeve ( 31 ) is formed, wherein a front side ( 39 ) of the injection sleeve ( 31 ) as a side wall of the formed as a circumferential groove recess ( 38 ) serves. Switching valve ( 27 ) according to one of claims 1 to 5, characterized in that the locking mechanism ( 37 ) two longitudinally displaceable in the transverse bore ( 40 ) arranged locking bolt ( 41 . 42 ), which by means of the compression spring ( 43 ) are biased in opposite directions, wherein in the transverse bore ( 40 ) at least one stop ( 44 ) is arranged, on which at least one locking bolt ( 41 . 42 ) abuts in its release position in the axial direction. Switching valve ( 27 ) according to one of claims 1 to 6, characterized in that one of the compression spring ( 43 ) opposite end of the locking bolt ( 41 . 42 ) is formed soon. Switching valve ( 27 ) according to claim 5, characterized in that the side wall of the latching recess ( 38 ) forming end face ( 39 ) of the injection sleeve ( 31 ), starting from the inner surface of which is provided with a chamfer. Switching valve ( 27 ) for actuating a device for varying a compression ratio of a reciprocating internal combustion engine, comprising a valve slide which can be moved into two different switching positions (US Pat. 28 ), which in a cylindrical receiving bore ( 30 ) arranged longitudinally displaceable and via a with a control terminal ( 32 ) communicating control room ( 33 ) at a first axially directed end face ( 34 ) can be acted upon with at least two different hydraulic control pressures, at least one return spring ( 35 ), with one of the first axially directed end face ( 34 ) remote from the second axially directed end face ( 36 ) of the valve spool ( 28 ) is acted upon by a restoring force, and at least one locking mechanism ( 37 ), with which the valve slide ( 28 ) is lockable in at least one of its switching positions, characterized in that the locking mechanism ( 37 ) is formed by at least one in the receiving bore ( 30 ) provided, acting in the axial direction of the valve slide, radially provided for this recess ( 38 ) by at least one within a control room ( 33 ) facing portion of the valve spool ( 28 ) arranged transverse bore ( 40 ), by at least one in the transverse bore ( 40 ) longitudinally displaceable locking bolt ( 41 . 42 ), between an engaged locking position, in which the first end in the latching recess ( 38 ) is engaged, and one of this disengaged release position is movable, and by at least one in the transverse bore ( 40 ) arranged compression spring ( 43 ), which together with the supplied via a longitudinal bore of the valve spool control pressure the locking bolt ( 41 . 42 ) acted upon at its second end in the direction of its locking position, that the latching recess ( 38 ) is provided in its locking direction with an oblique chamfering and that by a maximum control pressure of the valve slide ( 28 ) from its first switching position against the force of the return spring ( 35 ) is shifted in its second switching position, wherein the at least one locking pin ( 41 . 42 ) is disengaged at the beginning of the displacement of the valve spool against the control pressure and the force of the compression spring. Connecting rod ( 1 ) for a reciprocating internal combustion engine with adjustable compression ratio, which is at least two-stage adjustable to adjust the compression ratio in its effective length, comprising at least one adjusting device for adjusting the effective length of the connecting rod ( 1 ), at least one in a piston-side connecting rod eye ( 5 ) of the connecting rod ( 1 ) arranged eccentric ( 6 ), at least two acted upon by a hydraulic fluid hydraulic chambers, in each of which a control piston ( 14 . 15 ) is slidably mounted, and at least two piston rods, each having a control piston ( 14 . 15 ) with the eccentric ( 6 ), characterized by at least one switching valve ( 27 ) according to one of claims 1 to 9.

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