Connecting rod, changeover valve, check valve and internal combustion engine

Abstract

Connecting rod (1) for an internal combustion engine with adjustable compression ratio, with a lifting bearing eye (3) for connecting the same to a crankshaft, with a connecting rod bearing eye (2) for connecting the same to a piston of a cylinder, with an eccentric adjustment device (6) for adjusting an effective connecting rod length, wherein the eccentric adjustment device (6) has an eccentric (11) cooperating with an eccentric lever (9) and eccentric rods (4, 5) which are slidably guided in hydraulic chambers (13), wherein the eccentric adjusting device (6) has a switching valve (10) arranged in a first bore (7) of the connecting rod (1), the switching position of which determines which of the hydraulic chambers (13) is filled with hydraulic oil and which of the hydraulic chambers (13) is emptied, wherein the eccentric adjusting device (6) has check valves (15) arranged in second bores (23) of the connecting rod (1) which prevent the hydraulic oil from flowing back from the hydraulic chambers (13) into hydraulic oil supply lines (14), characterized by the fact that the changeover valve (10) and / or the check valves (15') are held in the respective bore (7, 23) such that a material recess (24, 25) is provided in the connecting rod (1) adjacent to the respective bore (7, 23) by forming a material web (19, 21) towards the respective bore, wherein the respective material web is positively inserted into a circular or elliptical or prismatic recess (26, 27') on the respective valve by forming it. the circular or elliptical or prismatic recess (26, 27') of the respective valve (10, 15') is formed on a radially outer surface of the respective valve, and the respective material web (19, 21) is inserted in the radial direction of the respective valve (10, 15') into the circular or elliptical or prism-shaped recess (26, 27') on the respective valve (10, 15').

Description

[0001] The invention relates to a connecting rod for an internal combustion engine with an adjustable compression ratio. The invention further relates to a switching valve and a check valve for such a connecting rod and an internal combustion engine.

[0002] In internal combustion engines, a high compression ratio has a positive effect on the engine's efficiency. The compression ratio is generally understood to be the ratio of the total cylinder volume before compression to the remaining cylinder volume after compression. In spark-ignition internal combustion engines, especially gasoline engines, which typically have a fixed compression ratio, the compression ratio must be chosen to be high enough to prevent engine knocking under full load. However, for the far more frequent partial load range of the internal combustion engine, i.e., with low cylinder filling, a higher compression ratio could be chosen without causing knocking. The partial load range of an internal combustion engine can be improved if the compression ratio is variably adjustable.

[0003] From DE 10 2010 016 037 A1, an internal combustion engine with an adjustable compression ratio is known. A connecting rod, which has a crankshaft bearing eye and a connecting rod bearing eye, can be connected to a crankshaft via the crankshaft bearing eye and to a cylinder piston of the internal combustion engine via the connecting rod bearing eye.

[0004] According to DE 10 2010 016 037 A1, an eccentric adjusting device is associated with the connecting rod. This device comprises an eccentric body consisting of an eccentric, an eccentric lever, and eccentric rods. The eccentric has a piston pin bore eccentrically arranged relative to the center point of the connecting rod bearing eye, with the piston pin bore accommodating a piston pin. The eccentric adjusting device serves to adjust the effective connecting rod length leff, where the connecting rod length is defined as the distance from the center point of the piston pin bore to the center point of the connecting rod bearing eye. The eccentric rods of the adjusting device are displaceable to rotate the eccentric body and thus change the effective connecting rod length. Each eccentric rod is associated with a piston, which is slidably guided in a hydraulic chamber.Hydraulic pressure is present in the hydraulic chambers, acting on the pistons associated with the eccentric rods. Depending on the amount of oil in the hydraulic chambers, the displacement of the eccentric rods may or may not be possible. The adjustment of the eccentric adjustment mechanism is initiated by the inertial and load forces of the internal combustion engine, which act on the eccentric adjustment mechanism during a power stroke. During a power stroke, the directions of the forces acting on the eccentric adjustment mechanism constantly change. The adjustment movement is assisted by the pistons, which are pressurized with hydraulic oil and act on the eccentric rods. The pistons prevent the eccentric adjustment mechanism from resetting due to the varying directions of the forces acting on it.The eccentric rods, which interact with the pistons, are attached to the eccentric lever of the eccentric body on both sides.

[0005] The hydraulic chambers, in which the pistons are guided, can be supplied with hydraulic fluid or hydraulic oil from the piston bearing eye via hydraulic oil supply lines. Check valves, arranged in bores of the connecting rod, prevent the hydraulic oil from flowing back from the hydraulic chambers into the hydraulic oil supply lines. A changeover valve is located in a bore of the connecting rod. The hydraulic chambers are connected to the bore containing the changeover valve via hydraulic oil drain lines. The switching position of the changeover valve determines which of the hydraulic chambers is filled with hydraulic oil and which is emptied or vented, thereby affecting the direction of adjustment or rotation of the eccentric adjustment device.

[0006] As explained, the hydraulic oil, which acts on the pistons of the eccentric rods guided in the hydraulic chambers, is supplied to the hydraulic chambers from the connecting rod bearing eye via the hydraulic oil supply lines. The connecting rod engages the crankshaft with the connecting rod bearing eye in such a way that a connecting rod bearing shell is positioned between the crankshaft (specifically, a crankshaft bearing journal) and the connecting rod bearing eye. The hydraulic chambers can be vented via the hydraulic oil drain lines, depending on the switching position of the changeover valve. This determines the direction of adjustment or rotation of the eccentric adjustment mechanism.

[0007] The switching valve known from DE 10 2010 016 037 A1 comprises an actuating element, a return spring and a control piston.

[0008] DE 10 2012 112 461 A1 and DE 10 2015 109 474 A1 disclose further switching valves for an internal combustion engine with an adjustable compression ratio known.

[0009] DE 10 2014 220 175 A1 also discloses a connecting rod for an internal combustion engine with an adjustable compression ratio.

[0010] DE 10 2015 103 467 A1 and WO 2016 / 169 670 A1 disclose details of a connecting rod with an adjustable compression ratio, which relate to the fastening of the eccentric rods to associated pistons or to the eccentric lever of the respective eccentric adjusting device.

[0011] As mentioned above, the connecting rod's changeover valve and check valves are positioned in bores in the connecting rod. Due to the continuous compressive and tensile forces acting on the connecting rod during operation, the connecting rod is subject to compression and stretching. This also affects the bores in which the changeover valve and check valves are located. Since the bores accommodating the valves, as well as the valves themselves, are subject to deformation by these forces, the valves can work their way out of the bores over time. This is a disadvantage. It is necessary to secure the valves in their positions within the bores to prevent them from working their way out as much as possible.

[0012] The object of the invention is to provide a novel connecting rod for an internal combustion engine with an adjustable compression ratio, a novel switching valve and check valve for such a connecting rod, and a novel internal combustion engine. This object is achieved by a connecting rod according to claim 1.

[0013] According to the invention, the switching valve and / or the check valves are held in the respective bore in such a way that a material recess is provided in the connecting rod adjacent to the respective bore by forming a material web towards the respective bore, wherein the respective material web is positively inserted into a circular or elliptical or prismatic recess on the respective valve by forming it.

[0014] According to the invention, the respective material web is inserted in the radial direction of the respective valve into the circular or elliptical or prismatic recess on the respective valve, wherein the circular or elliptical or prismatic recess of the respective valve is formed on a radially outer surface of the respective valve.

[0015] This ensures that the respective valve, i.e., the check valve or the changeover valve, is positively locked in its respective bore. This prevents the valve from being moved out of its bore due to deformation of the connecting rod caused by forces acting on it during operation. Simple, positive locking of the valve in its respective bore is possible using straightforward means.

[0016] In the area of ​​the changeover valve, the invention provides axial locking and anti-rotation protection for the valve. Axial locking and anti-rotation protection can also be implemented in the area of ​​the respective check valve using the invention.

[0017] In a further development, the respective material rib is inserted into the recess on the respective valve by crimping it. This further development of the invention is structurally particularly simple and therefore preferred for positively fixing the respective valve in the respective bore.

[0018] The switching valve according to the invention is defined in claim 4.

[0019] The check valve according to the invention is defined in claim 5.

[0020] The internal combustion engine according to the invention is defined in claim 6.

[0021] The inventive method for manufacturing a connecting rod according to the invention is defined in claim 7.

[0022] Preferred embodiments of the invention are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1. A perspective view of a connecting rod of an internal combustion engine with an adjustable compression ratio; Fig. 2 a detail of the connecting rod of the Fig. 1 in the area of ​​a switching valve; Fig. 3 another detail of the connecting rod with a partial cross-section in the area of ​​the switching valve; Fig. 4 the detail IV of the Fig. 3; Fig. 5 a side view of the switching valve; Fig. 6. A further cross-section through the connecting rod under the cut of a check valve; Fig. 7 the detail VII of the Fig. 1; Fig. 8 a side view of the check valve; and Fig. 9 a perspective view of an alternative check valve.

[0023] Fig. Figure 1 shows a schematic representation of a connecting rod 1 of an internal combustion engine with an adjustable compression ratio.

[0024] The connecting rod 1 has a connecting rod body 1a with a connecting rod bearing eye 2 and a crankshaft bearing eye 3. The connecting rod bearing eye 2 serves to connect the connecting rod 1 to a cylinder piston of a cylinder, the crankshaft bearing eye 3 serves to connect the connecting rod 1 to a crankshaft.

[0025] The connecting rod 1 of the internal combustion engine with adjustable compression ratio has an eccentric adjusting device 6 arranged at least partially in the connecting rod bearing eye 2, preferably hydraulically adjustable.

[0026] The eccentric adjusting device 6 has an eccentric 11 received in the connecting rod bearing eye 2 with a piston pin bore arranged eccentrically to a central axis 8 of the connecting rod bearing eye 2, wherein the piston pin bore has the central axis 8a.

[0027] The piston pin bore accommodates a piston pin (not shown) which connects the connecting rod 1 to the cylinder piston of the respective cylinder.

[0028] The eccentric adjustment device 6 is used to adjust the effective connecting rod length leff.

[0029] The effective connecting rod length leff is defined as the distance of a central axis 3a of the crank bearing eye 3 to the central axis 8a of the piston pin bore.

[0030] A rotation of the eccentric adjustment device 6 is initiated by the action of mass and load forces of the internal combustion engine, which act on the eccentric adjustment device 6 during a working stroke of the internal combustion engine.

[0031] During a working cycle, the directions of action of the forces acting on the eccentric adjusting device 6 change continuously. The rotary or adjusting movement is assisted by pistons pressurized with hydraulic fluid, in particular engine oil, which are guided in hydraulic chambers 13 of the connecting rod 1. The pistons prevent the eccentric adjusting device 6 from resetting due to the varying directions of action of the forces acting on the eccentric device 6.

[0032] The pistons of the eccentric adjusting device 6, which are guided in hydraulic chambers 13 of the connecting rod 1, are operatively connected on both sides to an eccentric lever 9 of the eccentric adjusting device 6 by means of eccentric rods 4, 5, wherein the eccentric lever 9 interacts with the eccentric 11.

[0033] The eccentric adjusting device 6 therefore comprises at least the eccentric rods 4 and 5, the pistons coupled to one end of the eccentric rods 4 and 5 and guided in the hydraulic chambers 13, the eccentric lever 9 coupled to the other end of the eccentric rods 4 and 5, and the eccentric 11 connected to the eccentric lever 9. The pistons or hydraulic chambers 13 are supplied with hydraulic fluid or hydraulic oil via hydraulic oil supply lines 14 from the lifting bearing eye 3 and check valves 15. The check valves 15 prevent the hydraulic oil from flowing back from the piston volumes of the pistons or the hydraulic chambers 13 into the hydraulic oil supply lines 14 towards the lifting bearing eye 3. The check valves 15 are accommodated in bores 23 of the connecting rod body 1a or the connecting rod 1.

[0034] The piston volumes or hydraulic chambers 13 are connected to a first hydraulic oil drain line 18 and a second hydraulic oil drain line 20, which interact with a changeover valve 10. The changeover valve 10 is located in a bore 7 of the connecting rod body 1a or the connecting rod 1. The changeover valve 10 determines, by its switching position, which piston volume or hydraulic chamber 13 is filled with hydraulic fluid and which piston volume or hydraulic chamber 13 is emptied.

[0035] A venting channel 22 for venting the respective hydraulic chamber 13 leads from the changeover valve 10 or the bore 7 accommodating the changeover valve to the lifting bearing eye 3.

[0036] The switching valve 10 has a cylindrical switching element 12 and a sleeve-shaped connecting section 16, wherein the switching element 12 is arranged in the connecting section 16 and is guided to be linearly displaceable in the longitudinal direction of the switching element 12 between switching positions to provide different compression ratios relative to the connecting section 16. The switching valve 10 therefore has the switching element 12 and the sleeve-shaped connecting section 16. The switching element 12 is at least partially inserted into the sleeve-shaped connecting section 16 and is displaceable relative to the connecting section 16.

[0037] As already explained, the changeover valve 10 is arranged in the bore 7 of the connecting rod 1 or the connecting rod body 1a. The check valves 15 are arranged in the bores 23 of the connecting rod 1 or the connecting rod body 1a.

[0038] According to the invention, the switching valve 10 and the check valves 15 are held or received in the respective bores 7 and 23, respectively, such that a material recess 24 and 25 is provided in the connecting rod 1 and the connecting rod body 1a adjacent to the bore 15 and 23 receiving the respective valve 10 and 15, respectively, by forming a material web 19 and 21 to the respective bore 7 and 23, respectively, wherein the respective material web 19, 21 is inserted or formed into a recess 26 and 27 on the respective valve 10 and 15, respectively, by forming it. This creates a positive fit between the connecting rod body 1a and the respective valve 10 or 15, which holds the respective valve 10 or 15 positively in the respective bore 7 or 23 in the connecting rod body 1a.

[0039] Fig. 3, Fig. 4 and Fig. Figure 5 illustrates the invention using the example of the changeover valve 10, which is received in the bore 7 of the connecting rod body 1a. The material recess 24 is formed in the connecting rod body 1a, with the material web 19 being formed adjacent to the bore 7 that receives the changeover valve 10. This material web 19 is formed or inserted into the recess 26 on the valve 10 by forming, preferably by flanging, thereby providing both axial retention and anti-rotation protection for the changeover valve 10, which is received in the bore 7. The recess 26 of the changeover valve 10, into which the material web 19 is formed by forming, is a circular, elliptical, or prismatic recess 26.The recess 26 is provided in a radially outer surface 17 of the switching valve 10, wherein the material web 19 is formed or inserted into the recess 26 by forming in the radial direction of the switching valve 10.

[0040] Fig. 6, Fig. 7, Fig. 8 and Fig. Figure 9 illustrates the invention for the positive locking fixation of a check valve 15 in the bore 23 of the connecting rod body 1a, wherein the material recess 25 is formed in the connecting rod body 1a adjacent to the bore 23 receiving the check valve 15, forming the material web 27. The material web 27 is formed into the recess 27 of the check valve 15 by deformation, so that the check valve 15 is positively locked in the bore 23. According to Fig. 8 is the recess 27 of the check valve 15, into which the material web 21 of the connecting rod body 1a is formed, on an outer cylindrical surface 28 of the check valve 15, wherein this recess 27 is in Fig. 6, Fig. 7 and Fig. 8 is designed as a circumferential groove or annular groove, not according to the invention. This ensures that the check valve 15 is positively locked in the bore 23 in the axial direction. To additionally provide an anti-rotation device for the check valve 15, according to the invention... Fig. 9 a recess 27' with a circular or prism-shaped cross-section is provided in the outer surface 28' of the check valve 15', into which the material web 21 is formed.

[0041] The invention further relates to a switching valve 10 and a check valve 15 for a connecting rod 1 of an internal combustion engine with a variable compression ratio.

[0042] The changeover valve 10 has a recess 26 on its radially outer surface 17, into which a material web 19 of the connecting rod body 1a can be formed by preferably flanging, in order to then hold the changeover valve 10 in the bore 7 receiving the changeover valve 10 in a form-fitting manner.

[0043] The check valve 15 has a recess 27 or 27' on its outer shell surface 28 or 28', into which the material web 21 can be formed, in particular by flanging, in order to hold the check valve 15 or 15' positively in the bore 23 receiving the check valve 15 or 15'.

[0044] The invention further relates to an internal combustion engine with at least one cylinder and with a crankshaft, wherein the coupling of the cylinder to the crankshaft is effected via a connecting rod 1 according to the invention.

[0045] The invention further relates to a method for manufacturing a connecting rod 1 of an internal combustion engine with a variable compression ratio.

[0046] To manufacture the connecting rod 1, the connecting rod body 1a is provided, which includes the hydraulic chambers 13, the bores 23 for receiving the check valves 15, and the bore 7 for receiving the changeover valve 10. Furthermore, an eccentric adjusting device is provided, which has a changeover valve 10 and / or check valves 15 according to the invention. A material recess 24 is formed in the connecting rod body 1a adjacent to the bore 7 receiving the changeover valve 10. Alternatively or additionally, material recesses 25 are formed in the connecting rod body 1a adjacent to the bores 23 receiving the check valves 15, each forming the corresponding material web 19 or 21.

[0047] After the introduction of these material recesses 24 and / or 25, the switching valve 10 is arranged in the bore 7, and the check valves 15 are placed in the bores 23.

[0048] The corresponding material webs 19 and 21 are subsequently reshaped by forming the material webs 19 and 21 into the respective recess 16 and 27, 27' of the respective valve 10 and 15, 15', respectively, in order to fix the respective valve 10, 15, 15' positively in the respective bore 7, 23.

Claims

[1] Connecting rod (1) for an internal combustion engine with adjustable compression ratio, with a crank bearing eye (3) for connecting it to a crankshaft, with a connecting rod bearing eye (2) for connecting it to a piston of a cylinder, with an eccentric adjustment device (6) for adjusting an effective connecting rod length, wherein the eccentric adjusting device (6) has an eccentric (11) cooperating with an eccentric lever (9) and eccentric rods (4, 5) which are displaceably guided in hydraulic chambers (13), wherein the eccentric adjusting device (6) has a switching valve (10) arranged in a first bore (7) of the connecting rod (1), the switching position of which determines which of the hydraulic chambers (13) is filled with hydraulic oil and which of the hydraulic chambers (13) is emptied, wherein the eccentric adjusting device (6) has check valves (15) arranged in second bores (23) of the connecting rod (1), which prevent the hydraulic oil from flowing back from the hydraulic chambers (13) into hydraulic oil supply lines (14), characterized by , that the changeover valve (10) and / or the check valves (15') are held in the respective bore (7, 23) in such a way that a material recess (24, 25) is introduced into the connecting rod (1) adjacent to the respective bore (7, 23) to form a material web (19, 21) to the respective bore, wherein the respective material web is positively inserted into a circular or elliptical or prism-shaped recess (26, 27') on the respective valve by forming the same, the circular or elliptical or prism-shaped recess (26, 27') of the respective valve (10, 15') is formed on a radially outer surface of the respective valve, and the respective material web (19, 21) is inserted in the radial direction of the respective valve (10, 15') into the circular or elliptical or prism-shaped recess (26, 27') on the respective valve (10, 15'). [2] Connecting rod according to claim 1, characterized by that the respective material web (19, 21) is inserted into the recess on the respective valve (10, 15') by flanging it. [3] Connecting rod according to claim 1 or 2, characterized by that the respective valve (10, 15') is held in the respective bore in a form-fitting manner in the axial direction of the respective valve (10, 15') by the material web (19, 21) formed into the respective recess of the valve. [4] Changeover valve (10) of a connecting rod (1) according to one of claims 1 to 3, with a circular or elliptical or prism-shaped recess (26) formed on a radially outer circumferential surface. [5] Check valve (15') of a connecting rod (1) according to one of claims 1 to 3, with a circular or elliptical or prism-shaped recess (27') formed on a radially outer circumferential surface. [6] Internal combustion engine, with at least one cylinder and with a crankshaft to which at least one connecting rod (1) engages, wherein the or each connecting rod (1) is designed according to one of claims 1 to 3. [7] Method for producing a connecting rod (1) according to one of claims 1 to 3, Providing a connecting rod base body (1a) with a first bore (7) for receiving the changeover valve (10) and second bores (23) for receiving the check valves (15'), Providing an eccentric adjustment device (6) which has a changeover valve (10) according to claim 4 and / or check valves (15') according to claim 5, Making a material recess (24) in the connecting rod base body (1a) adjacent to the first bore (7) to form a material web (19) to the first bore (7) and / or making material recesses (25) in the connecting rod base body (1a) adjacent to the second bores (23) to form a material web (21) to the respective second bore (23), Arranging a changeover valve (10) according to claim 4 in the first bore (7) and / or arranging the check valves (15') according to claim 5 in the second bores (23), Forming the material web (19) to form the first bore (7) and / or the material web (21) to form the respective second bore (23) into the circular or elliptical or prism-shaped recess (26, 27') on the respective valve (10, 15').

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