EP1085184A2 - 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. A locking element (51) can be brought to engage the sleeve to prevent it from rotating. The locking element is positioned using a piston and cylinder unit (54). An Independent claim is included for a method for using the device.

Description

The invention relates to a device for changing the compression of a Reciprocating internal combustion engine according to the preamble of claim 1 and a method to change the compression of a reciprocating internal combustion engine according to Preamble of claim 9.

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 and two circumferential edge flanges overlapping the connecting rods. The Compression of the reciprocating internal combustion engine is due to a change in Rotational position of the sleeve possible, the sleeve in the respective rotational position by means of one which can be brought into engagement with locking recesses in the edge flanges Locking member can be locked, which is part of a locking device. The For this purpose, the locking member is connected to a lever which can be pivoted about an axis and is guided by a cam device so that it occupy two positions can, the locking member in a first position in the Locking recess of the first edge flange of the sleeve and in the other Position engages in the locking recess in the other edge flange. Because of the complex mechanics for moving the locking member are the cost of Device up. In addition, the parts are subject to the locking device mechanical wear, which adversely affects the functional reliability of the Device can impact.

It is therefore an object of the invention to a device of the type mentioned create a simple and therefore inexpensive structure. Another one The goal is to find a method to change the compression of a Reciprocating internal combustion engine to provide a high level of functional reliability can be guaranteed.

To achieve the object, a device having the features of claim 1 suggested. This is characterized in that the locking element with the help a piston and cylinder unit is displaceable. After a first variant is the locking element with a piston of the piston and cylinder unit coupled, which is guided displaceably in a cylinder attached to the connecting rod and divided the cylinder into two work rooms. When the piston and Cylinder unit, the piston is displaced relative to the cylinder, whereby the Locking element in the direction of the sleeve in a locking position or in opposite direction is disengaged from the sleeve. After a second embodiment variant, the locking element is coupled to the cylinder, which is relatively movable compared to the piston attached to the connecting rod. The device is subject to very little wear, so that a high level of functional reliability can be guaranteed. Moreover, by the piston and cylinder unit simple and compact structure can be realized.

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.

An embodiment of the device is particularly preferred which is characterized by distinguishes that the piston and cylinder unit is a hydraulic piston and Cylinder unit is, that is, that to move the piston relative to the Cylinder or the cylinder relative to the piston at least one the working spaces of the cylinder with a pressurized fluid, for example Pressure oil from the engine lubricating oil circuit, can be acted upon. The pushing back and forth the piston in the cylinder can be realized, for example, that the Workrooms are filled alternately with the pressure medium. Another one The embodiment of the device is the piston and cylinder unit with compressed air operated, the structure and mode of operation essentially with that of the hydraulic Piston and cylinder unit matches.

According to a development of the invention it is provided that in at least one of the two working spaces of the cylinder at least one the piston with a compressive force acting spring element, for example a compression spring, is arranged. The Spring element serves the piston and thereby also that connected to the piston Locking element in the depressurized state of the piston and cylinder unit or at Falling below a threshold pressure of that in the other work space Relocate the print medium independently. The arrangement of the spring element in the cylinder can be chosen so that it is the locking element out of engagement with the sleeve brings so that a rotation of the sleeve to change the compression of the Reciprocating internal combustion engine is possible. In another embodiment the locking element from the spring element for fixing the rotational position of the sleeve into a through opening, blind hole or open-edged recess in the sleeve crowded. It is advantageous in these embodiments that only for one of the two Working spaces of the cylinder a pressure medium supply is required, which the Structure of the device can be simplified.

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

To solve the problem, a method is also proposed that the characteristics of Claim 9 has. The procedure for changing the compression of a Reciprocating piston internal combustion engine, in which one for the determination of the rotational position is large Connecting rod eye of a connecting rod rotatably arranged sleeve at least one with the sleeve engageable locking element is used, that the Locking element is displaced by means of a gaseous or fluid pressure medium. The process is characterized by a high level of functional reliability and enables a simple structure of a device used for this.

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 a locking device 52 with one in the Figures 1 and 6 shown locking element 51, here on the connecting rod lower 11th is arranged and serves the sleeve 13 against in its two rotational positions Secure twisting. To move the locking element 51 in the direction of the Sleeve 13 and in the opposite direction is a hydraulic piston and Cylinder unit 54 is provided. In the embodiment shown in Figure 1 is the locking element 51 perpendicular to the longitudinal central axis of the connecting rod eye 7 or arranged to the crankshaft axis of rotation and in the direction of a Double arrow 57 relocatable. The locking element 51 is of one here cylindrical locking bolt 55 formed in one piece with a piston 53 of the Piston and cylinder unit 54 is formed. The locking bolt 55 engages in one first functional position in one of the circumference of the first bearing shell 15 introduced through openings 59, 61 or into a through opening 60 in the second bearing shell 17 (FIG. 5). In a second functional position Locking bolt 55 moved out of the through opening 59, 60, 61, so that the sleeve 13 is rotatable. In which of the circumferential direction of the bearing shell 15 in a distance of approximately 5 ° arranged through openings 59, 61 of the Locking bolt 55 is retractable to prevent rotation of the sleeve 13 is dependent from the respective rotational position of the sleeve 13.

The piston 53 divides a cylinder 63, which is attached here to the connecting rod lower part 11 Piston and cylinder unit 54 in two working spaces 65 and 67, of which the Working space 65 can be acted upon with a hydraulic pressure medium. With this The exemplary embodiment is the pressure oil from the engine lubricating oil circuit as the pressure medium used. In the other working space 67 is formed by a compression spring Spring element 69 is arranged, which falls below a certain pressure (Threshold pressure) in the working space 65 displaces the piston 53 within the cylinder 63 so that the locking bolt 55 is displaced away from the sleeve 13 and, if necessary, from 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 by the pressure oil from the connecting rod bearing in the Dashed line indicated work space 65 of the cylinder 63 can be directed. In this exemplary embodiment, the piston 53 faces the working space 65 facing side has a recess, whereby an annular surface 73 is formed, the the pressure oil can be acted on, so that the locking bolt 55 in a Locking / locking position is shifted, in which it in one of the through openings 59, 61 in the bearing shell 15 or in the through opening 60 in the Bearing shell 17 engages.

Instead of the through openings 59, 60 and 61 in the bearing shells 15, 17, in which the Locking element 51 engages in its locking position, can also edge-open recesses or blind holes may be provided, the Pressure oil supply in the sleeve 13 for the piston and cylinder unit 54 accordingly is adjusted.

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 Rotation of the sleeve 13 clockwise (arrow 72) in its second rotational 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 (9)

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, and with at least one with the sleeve to the latter Locking device comprising locking element which can be brought into engagement, characterized in that the locking element (51) can be displaced with the aid of a piston and cylinder unit (54). Apparatus according to claim 1, characterized in that the piston and cylinder unit (54) is a pneumatic piston and cylinder unit or hydraulic piston and cylinder unit. Device according to Claim 1 or 2, characterized in that the locking element (51) is coupled to a piston (53) which divides a cylinder (63) of the piston and cylinder unit (54) into two working spaces (65; 67). Device according to one of the preceding claims, characterized in that at least one of the working spaces (65; 67) can be acted upon by a pressurized hydraulic medium, preferably lubricating oil. Device according to one of the preceding claims, characterized in that at least one spring element (69) acting on the piston (53) with a compressive force is arranged in at least one working space (65; 67). Device according to one of the preceding claims, characterized in that the locking element (51) can be displaced out of engagement with the sleeve (13) when the pressure medium in the working space (65; 67) falls below a threshold pressure by means of the spring element (69). Device according to one of the preceding claims, characterized in that the locking element (51) can be displaced parallel or radially to the crankshaft axis of rotation. Device according to one of the preceding claims, characterized in that the locking element (51) and the piston (53) are penetrated by a supply channel (through hole (71)) for the pressure medium, via which at least one of the working spaces (65; 67) the pressure medium is feedable. Method for changing the compression of a reciprocating piston internal combustion engine, in which at least one locking element is brought into engagement with the sleeve in order to determine the rotational position of a sleeve rotatably arranged in a connecting rod eye of a connecting rod, characterized in that the locking element is displaced by means of a gaseous or fluid pressure medium.

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