EP1085185A2 - Device and method for varying the compression ratio of an internal combustion engine - Google Patents

Abstract

The device (1) has a sleeve (13) that fits in the big end (7) of a connecting rod (3). The sleeve has an opening (19) for the crankshaft and is rotatably fitted, in an eccentric position with respect to the big end. The sleeve or the connecting rod has at least one working chamber (45,47) acted on by an abutment (35) attached to a piston (53) operated with a pressurised medium to rotate the sleeve.

Description

The invention relates to a device for changing the compression of a Reciprocating internal combustion engine according to the preamble of claim 1.

Devices of the type mentioned here are known. They serve the Compression of a reciprocating piston internal combustion engine at its operating states, i.e. partial load or full load. For this, the stroke of a connecting rod is the Reciprocating internal combustion engine changed accordingly.

DE 197 03 948 C1 discloses a device with a connecting rod, in the a large connecting rod eye associated with a crankshaft rotatably arranged a sleeve is. The sleeve has a crankshaft through opening arranged eccentrically to the large connecting rod eye on. The compression of the reciprocating internal combustion engine is by a Change the rotational position of the sleeve possible, the sleeve in the respective Rotational position can be locked by means of a locking member. The twist of the sleeve takes place automatically after release by the locking member on the basis of it by the rotation of the crankshaft or the oscillating movement of the Connecting rod forces. The disadvantage is that often a rapid rotation of the Sleeve in a defined rotational position is not done in the desired manner. For twisting the sleeve is also proposed to a gear pump in the connecting rod integrate a toothed wheel which engages in a toothing provided on the sleeve includes. The disadvantage here is the large manufacturing effort and the costs for this additional parts.

DE 31 27 760 A1 discloses a device in which the rotation of the large connecting rod eye arranged, an eccentric compared to the large connecting rod eye Crankshaft passage opening sleeve using a fixed to the sleeve connected push rod, which is guided in a sliding guide. An adjustment the sliding guide to another position causes the sleeve to twist. The Design of this mechanical actuating device is very complex and thus expensive.

It is therefore an object of the invention to a device of the type mentioned create that through a low weight and a small footprint distinguished and has a simple and therefore inexpensive structure.

To achieve the object, a device having the features of claim 1 suggested. This is characterized in that the sleeve or the connecting rod for Rotation of the sleeve at least one pressurizable with a pressure medium Has working chamber. The sleeve is thus twisted by the insertion a medium under pressure, for example pressure oil from the Engine lubricating oil circuit, in the working chamber. The working chamber has the function of a cylinder, while the piston cooperating with the cylinder by one fixed part on the connecting rod or connecting rod or on the sleeve or sleeve is formed. In the embodiment in which the sleeve has the working chamber, takes place when the pressure medium is applied to the working chamber Relative movement of the cylinder in relation to the piston. The other Embodiment in which the connecting rod acts as a cylinder working chamber and Sleeve has a portion or area acting as a piston, the piston becomes relative moved relative to the cylinder. The device is characterized by a simple and therefore inexpensive construction and high functional reliability. It is also advantageous that the device has practically no wear has underlying components. Furthermore, the space requirement and the weight of the Device preferably only very little.

In connection with the present invention, the term "Twist" of the sleeve to take different rotational positions both a Pivoting the sleeve clockwise and counterclockwise as well as rotating the Sleeve understood in one direction.

According to a development of the invention it is provided that the working chamber of one the function of a piston fixed with respect to the connecting rod or the sleeve having the stop is completed. With the help of the stop is the rotary position the sleeve can be fixed with respect to the connecting rod, the sleeve in at least two Rotational positions can be rotated. Due to the double function of as a piston and as The position of the stop which serves to fix the rotational position can be the construction of the device be simplified.

In addition, an embodiment of the device is preferred, which is characterized by characterized in that the crankshaft has at least one channel for the pressure medium, the at least within a crankshaft rotational position range in the working chamber flows. With each revolution of the crankshaft, at least one passes over the Crankshaft through opening through connecting rod bearing pin provided Channel opening the working chamber with the pressure medium, whereby the Medium of the working chamber in increments in certain, from the rotational position of the Crankshaft dependent intervals supplied or from the working chamber can be applied. Alternatively, it is possible to use an annular groove or the like between the channel and the working chamber in any rotational position of the Crankshaft is a medium connection, so that the medium continuously in the Work chamber initiated or can be transported out of this.

Finally, an embodiment of the device is preferred in which in seen in the radial direction of the crankshaft a further working chamber on the sleeve or the connecting rod is designed to reverse the sleeve. In this embodiment the sleeve is thus designed to be pivotable, that is to say when one is pressurized the working chambers the sleeve turns clockwise and when pressurized the other working chamber in the opposite direction about the longitudinal central axis of the large connecting rod eye pivoted. This is a hydraulic only Averaged twisting of the sleeve is possible.

Further advantageous embodiments of the device result from the rest Dependent claims.

Figur 1

eine perspektivische Darstellung eines Ausführungsbeispiels eines mehrteiligen Pleuels einer Hubkolbenbrennkraftmaschine;

Figur 2

eine perspektivische Darstellung eines Oberteils des in Figur 1 dargestellten Pleuels;

Figur 3

eine perspektivische Darstellung eines Unterteils des in Figur 1 dargestellten Pleuels;

Figur 4

eine perspektivische Darstellung eines ersten Teils eines Ausführungsbeispiels einer mehrteiligen Lagerhülse;

Figur 5

eine perspektivische Darstellung eines zweiten Teils der Lagerhülse und

Figur 6

eine Seitenansicht eines Ausführungsbeispiels eines Verriegelungselements zur Verdrehsicherung der Lagerhülse.

The invention is explained below with reference to the drawing. Show:

Figure 1

a perspective view of an embodiment of a multi-part connecting rod of a reciprocating internal combustion engine;

Figure 2

a perspective view of an upper part of the connecting rod shown in Figure 1;

Figure 3

a perspective view of a lower part of the connecting rod shown in Figure 1;

Figure 4

a perspective view of a first part of an embodiment of a multi-part bearing sleeve;

Figure 5

a perspective view of a second part of the bearing sleeve and

Figure 6

a side view of an embodiment of a locking element to prevent rotation of the bearing sleeve.

FIG. 1 shows an embodiment of a device 1 in a perspective view to change the compression of a reciprocating internal combustion engine, namely a Connecting rod 3, which has a small connecting rod eye 5 for mounting a piston pin and a large one Connecting rod eye 7 for supporting a connecting rod bearing journal of a crankshaft. The Connecting rod 3 is in two parts to form a split bearing for the connecting rod bearing journal formed and comprises a connecting rod upper part 9 and a connecting rod lower part 11, which means by not shown fasteners are releasably connectable. In the big connecting rod eye 7 is a two-part sleeve 13 is arranged, the first bearing shell 15 and one second bearing shell 17. The preferably made of steel, at her Inner circumference coated with a bearing material sleeve 13 has a crankshaft through opening 19, which is arranged eccentrically to the large connecting rod eye 7. The Bearing shells 15, 17 of the sleeve 13 rotatable in the connecting rod eye 7 are on it Outside shaped differently, which will be discussed in more detail below.

FIG. 4 shows a perspective illustration of the one described with reference to FIG. 1 first bearing shell 15 of the sleeve 13, the outer contour partially to the Inner contour of the large connecting rod eye 7 is adapted. The inner contour of the connecting rod eye 7 is uniform over its entire circumference, as can be seen from FIGS. 2 and 3, each of which is a perspective view of the connecting rod upper part 9 or the connecting rod lower part 11 emerges without the sleeve 13. In the The outer circumference of the first bearing shell 15 is on the inner contour of the connecting rod eye 7 Appropriately adapted grooves 21 are introduced with different depths, whereby a first bearing shoulder 23 and a second bearing shoulder 25 are formed. Moreover, the first bearing shell 15 contact surfaces 27 and 27 'with which they are in the assembled state abuts the second bearing shell 17. The contact surfaces 27, 27 'can be flat be formed and have no depressions.

der zweiten Lagerschale 17 mit einem in Figur 3 dargestellten Anschlag 35 zusammen, der hier von einer Anschlagplatte 37 gebildet ist. Die Anschlagplatte 37 ist im montierten Zustand zwischen dem Pleueloberteil und -unterteil angeordnet und weist in das Pleuelauge 7 hineinragende -in Figur 3 gestrichelt dargestellte- Anschlagflächenbereiche 38 und 38' auf, die mit den Anschlagflächen 29, 29' der zweiten Lagerschale 17 zusammenwirken. Die Oberseite 49 eines der Anschlagflächenbereiche 38, 38' bildet eine erste Kolbenfläche für eine erste Arbeitskammern 45, die zwischen dem Außenrücken der ersten Lagerschale 15 und dem Pleuelunterteil 11 gebildet ist. Die Unterseite 50 des anderen Anschlagflächenbereichs bildet eine zweite Kolbenfläche für eine zweite Arbeitskammer 47, die zwischen dem Außenrücken der ersten Lagerschale 15 und dem Pleueloberteil 9 gebildet ist.Figure 5 shows a perspective view of the second bearing shell 17 of the sleeve 13 obliquely from above. The second bearing shell 17 is completely adapted on its outer contour to the inner contour of the large connecting rod eye 7, like the first bearing shell 15, and has stop surfaces 29 and 29 ', which in the assembled state of the sleeve 13 on the contact surface 27 and 27' of the first Bearing shell 15 abut. In the stop surfaces 29, 29 ', open-edge depressions 31 and 31' are provided, which are provided for distributing a printing medium. The stop surfaces 29, 29 also act

the second bearing shell 17 together with a stop 35 shown in Figure 3, which is formed here by a stop plate 37. In the assembled state, the stop plate 37 is arranged between the upper and lower connecting rod parts and has stop surface regions 38 and 38 'protruding into the connecting rod eye 7, shown in dashed lines in FIG. 3, which interact with the stop surfaces 29, 29' of the second bearing shell 17. The top 49 of one of the stop surface areas 38, 38 ′ forms a first piston surface for a first working chamber 45, which is formed between the outer back of the first bearing shell 15 and the connecting rod lower part 11. The underside 50 of the other stop surface area forms a second piston surface for a second working chamber 47, which is formed between the outer back of the first bearing shell 15 and the connecting rod upper part 9.

In the exemplary embodiment of the device 1 shown in FIG. 1, the sleeve is 13 Can be rotated by approximately 175 ° in the connecting rod eye 7, the two rotational positions of the sleeve 13 are determined by the stop 35. In this embodiment, the Angular range of the sleeve 13 determined by the thickness of the stop 35. In a 1, the second bearing shell 17 strikes with a their stop surfaces 29, 29 'from above against the stop 35 or the Stop surface areas 38, 38 'and in the other, opposite the first rotational position rotated clockwise by approximately 175 ° from the bottom against the Stop surface areas 38, 38 '.

In the inner circumferential surface 39 of the second bearing shell 17, annular groove sections 41 and 43 are introduced, which extend in the circumferential direction of the crankshaft penetration opening 19 and extend through the stop surfaces 29, 29 'into the respective recess 31, 31'. The annular groove sections 41, 43 form collecting chambers which can be acted upon by a pressure medium. The cavity located in the assembled state between the bearing shell 15 and the connecting rod lower part 11 and the connecting rod upper part 9 represents the working chamber 45 and 47, respectively. The working chambers 45, 47 are circumferential by the stop plate 37 and the stop surfaces 29, 29 or the depressions 31, 31 limited.

In a preferred embodiment, the working chambers 45, 47 are with pressure oil can be loaded from the engine lubricating oil circuit, the working chambers 45, 47 have separate pressurized oil supplies. The pressure oil supply, for example via a multi-way valve, not shown in the figures, and two main oil galleries in a crankcase receiving the crankshaft with tap holes to the Main crankshaft bearings realized. The crankshaft main bearings are above each at least one channel in the crankshaft with the connecting rod bearing journals and arranged in this channel openings with the working chambers 45, 47 in Flow connection.

The device 1 also includes one shown in Figures 1 and 6 Locking element 51, which is arranged here on the connecting rod lower part 11 and serves to to secure the sleeve 13 against twisting in its two rotational positions. The Locking element 51 comprises a fixedly connected to a piston 53 Locking bolt 55, in the embodiment shown in Figure 1 perpendicular to the longitudinal central axis of the connecting rod eye 7 or Longitudinal rod axis arranged and displaceable in the direction of a double arrow 57. The In a first functional position, locking bolt 55 engages in one of the circumferences the first bearing shell 15 introduced through openings 59, 61 and into a through opening 60 in the second bearing shell 17 (FIG. 5). In a second functional position is the locking bolt 55 from the through opening moved out so that the sleeve 13 is rotatable. In which of the circumferential direction the bearing shell 15 at a distance of approximately 5 ° arranged through openings 59, 61 the locking bolt 55 is retractable to prevent rotation of the sleeve 13 depending on the respective rotational position of the sleeve 13. The piston 53 divides one Cylinder 63 in two working spaces 65 and 67, of which the working space 65 with one Pressure medium, for example pressure oil from the engine lubricating oil circuit, can be acted upon is. In the other working space 67 there is a spring element 69 formed by a compression spring arranged, which falls below a certain pressure in the work space 65 den Piston 53 displaced within the cylinder 63 so that the locking bolt 55 of the sleeve 13 is displaced and, if necessary, out of one of the through openings 59, 60, 61 is pulled out.

From Figure 6 it can be seen that the piston 53 and the locking pin 55 of one Through hole 71 are penetrated through the pressure oil from the connecting rod bearing in the Working space 65 of the cylinder 63 can be directed. The piston 53 has this Embodiment on its side facing the working space 65 a recess on, whereby an annular surface 73 is formed, which can be acted upon by the pressure oil, so that the locking bolt 55 is shifted into a locking / locking position in the in one of the through openings 59, 61 in the bearing shell 15 or in the Through opening 60 engages in the bearing shell 17.

In a further embodiment, not shown in the figures, this is Locking element arranged parallel to the axis of rotation of the crankshaft and engages in one in one of the bearing shoulders of the two bearing shells 15, 17 of the sleeve 13 introduced recess.

The function of that described with reference to FIGS. 1 to 5 is described below Device 1 described in more detail: The rotational position of the sleeve 13 shown in FIG. 1 corresponds to the minimum compression of the reciprocating piston internal combustion engine. In this Rotational position abuts the second bearing shell 17 against the stop 35 from above Turn the sleeve 13 clockwise (arrow 72) to its second rotary position, in the the second bearing shell 17 abuts the stop 35 from below, it will Locking element 51 out of engagement with the sleeve 13 or the Bearing cups 15, 17 brought. Then the one pressure chamber 47 with pressure oil acts, whereby the sleeve 13 is pushed away from the stop 35 until it has reached its other rotational position in which the second bearing shell 17 from below strikes the stop 35. Finally, the locking element 51 for fixing the Sleeve 13 shifted and the locking bolt 55 in the corresponding Through opening 59, 60, 61 retracted. A return rotation of the sleeve 13 from one Rotational position in the other rotational position is achieved in that the locking element 51 shifted from its rest position into a waiting position and the other pressure chamber 45 is now filled with pressure oil, whereby the sleeve 13 counterclockwise is rotated back into its rotational position shown in Figure 1. Doing so simultaneously press out the pressure medium in the other, unpressurized working chamber and can again, for example via the channel in the crankshaft Engine lubricating oil circuit are supplied.

The device 1 described with reference to the figures is characterized in particular by a cost-effective construction and also has a high level of functional reliability.

Claims (6)

Device for changing the compression of a reciprocating piston internal combustion engine with at least one connecting rod, in the connecting rod eye of which a crankshaft can be assigned a sleeve with a crankshaft passage opening is rotatably arranged, the crankshaft passage opening being arranged eccentrically to the connecting rod eye, characterized in that the sleeve (13) or the connecting rod (3) for rotating the sleeve (13) has at least one working chamber (45; 47) to which a pressure medium can be applied. Device according to Claim 1, characterized in that the working chamber (45; 47) is closed off by a stop (35) which has the function of a piston which is fixed relative to the connecting rod (3) or the sleeve (13). Apparatus according to claim 1 or 2, characterized in that the working chamber (45; 47) ― depending on the rotational angle position of the sleeve (13) - from an outer peripheral region of the sleeve (13) and a first bearing shell (15) or a second bearing shell (17) the at least two-part sleeve (13) is formed. Device according to one of the preceding claims, characterized in that the crankshaft has at least one channel for the pressure medium which opens into the working chamber (45; 47) at least within a crankshaft rotational position range. Device according to one of the preceding claims, characterized in that, seen in the radial direction of the crankshaft, a further working chamber (45; 47) is formed on the sleeve (13) or the connecting rod (3) for turning the sleeve (13) back. Device according to one of the preceding claims, characterized in that the stop (35) forms with its one side a piston surface for the one working chamber (45; 47) and with its other side a piston surface for the other working chamber (47; 45).

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