DE102017202392A1 - Crankcase for a reciprocating internal combustion engine - Google Patents

Abstract

Crankcase for a reciprocating internal combustion engine, which has at least one cylinder bore with a cylinder wall for Hubbeweglichen leadership of a piston, in particular a steel piston which is operatively connected via a connecting rod with a crankshaft, wherein the piston has a pressure side, with which he in the region of top dead center (TDC) exerts an increased surface pressure on the cylinder wall, wherein the cylinder wall in the region of increased surface pressure on the outside of the cylinder bore side has a material reinforcement.Durch the inventive design can influence the smallest possible weight increase the strength of the cylinder bore with a minimum package be greatly increased, which has a positive effect on the durability and the acoustics especially when using a steel piston in a light metal crankcase.

Description

The invention relates to a crankcase for a reciprocating internal combustion engine with the features of the preamble of patent claim 1.

• - Bei kalter Brennkraftmaschine macht sich das Verkippen, insbesondere bei Leichtmetallkolben, noch stärker bei Stahlkolben, durch ein lästiges Geräusch bemerkbar, das sogenannte „Kolbenklappern“. Um dieses Kolbenklappern zu unterdrücken sind mit großem Aufwand sogenannten Regelkolben entwickelt worden. Regelkolben sind Kolben mit eingegossenen Stahlstreifen.
• - Die Zylinderbuchsen werden zu hochfrequenten Schwingungen angeregt, denen das Kühlmittel nicht mehr folgen kann, so dass es im Kühlmittelmantel zu Kavitation mit den bekannten Folgen, wie z. B. Lochfraß im Kurbelgehäusematerial, kommen kann.
• - Im schlimmsten Fall kann das Kolbenkippen dazu führen, dass die Zylinderbuchsen im Berührungsbereich mit dem Kolben reißen.

For technical environment is for example on the US patent US 4,461,247 pointed. From this patent a crankcase for a multi-cylinder internal combustion engine is known. In the cylinder liners of the crankcase each piston are arranged liftable. Within the crankcase, the cylinder liner is largely radially surrounded by a coolant jacket. During operation of the internal combustion engine, the piston may tilt due to the gas forces and the mechanical forces within the cylinder liner, wherein the piston skirt of the piston contacts the cylinder liner in a cylinder liner region. That is, the piston is pushed from one side to the other side of the cylinder bore, with the undesirable consequences:

• - In cold engine makes the tilting, especially in light metal piston, even more so in steel pistons, noticeable by a troublesome noise, the so-called "piston rattling". In order to suppress this piston rattling so-called control piston have been developed with great effort. Control pistons are pistons with cast-in steel strips.
• - The cylinder liners are excited to high-frequency vibrations, which can no longer follow the coolant, so that it in the coolant jacket to cavitation with the known consequences, such. B. pitting in the crankcase material, can come.
• - In the worst case, the piston butt can cause the cylinder liners to break in the area of contact with the piston.

In order to minimize the effects of piston tilting, it is proposed in the above-referenced US patent to pull the closure wall from the coolant jacket to the cylinder head of the closed deck crankcase down within the coolant jacket to create a bifurcated coolant jacket (top and bottom) and annoying Rattling noises are dampened by the deeper closed deck.

A disadvantage of the proposed embodiment, the division of the cooling jacket in an upper coolant jacket and a lower coolant jacket in the cylinder liners. An optimal cooling of the cylinder liners over their entire height is thus very expensive to represent.

For this reason, in the German Offenlegungsschrift DE 10 2012 204 805 A1 , from which the present invention proceeds, proposed a crankcase for an internal combustion engine, with at least one cylinder liner made of a light metal, in which a piston, also made of a light metal is arranged to lift. The cylinder liner is at least partially radially surrounded by a coolant jacket, which is delimited by the cylinder liner and the crankcase, wherein the piston tilt during operation of the internal combustion engine by acting on him mechanical forces and gas forces in the cylinder liner and a piston skirt of the piston, the cylinder liner in a cylinder liner area can touch. According to the invention is in the DE 10 2012 204 805 A1 proposed that in the coolant jacket, a rib is arranged, which supports at least the cylinder liner portion against the crankcase, in which the piston skirt of the piston contacts the cylinder liner.

Although this proposed embodiment has proven itself in aluminum piston or light metal piston, but the proposed embodiment is not sufficient in the use of steel pistons, which have a different thermal expansion behavior than light metal piston.

Object of the present invention is to show a measure to avoid the above-mentioned disadvantages when using a steel piston in a light metal crankcase.

This object is achieved by the feature in the characterizing part of patent claim 1.

The inventive design of the crankcase has only a minimal package influence on the crankcase, a very small increase in weight compared to rotationally symmetric reinforcements result, or other known ribs and configurations.

Advantageous developments of the invention are described in the subclaims.

Thus, the dimensions according to claims 2 to 4 are particularly preferred sizes.

A special wear resistance of the cylinder bore is achieved by the embodiment according to claims 5 and 6.

Particularly advantageous is the crankcase according to claim 7 made of a light metal, such as. As an aluminum-silicon alloy, especially in conjunction with a steel piston.

The embodiment according to claim 8 is a preferred variant, and an inlet-side arrangement is possible.

Due to the configuration according to claim 9 is a simple and cost-effective production, for example in a low-pressure casting or die casting possible.

• 1 zeigt eine Aufsicht auf ein Kurbelgehäuse gemäß dem Stand der Technik.
• 2 zeigt eine Aufsicht auf ein Kurbelgehäuse gemäß der Erfindung.

In the following the invention is explained in more detail with reference to two figures.

• 1 shows a plan view of a crankcase according to the prior art.
• 2 shows a plan view of a crankcase according to the invention.

The following apply in the figures 1 and 2 for same components the same reference numbers.

1 shows a plan view of a crankcase 1 according to the prior art. Shown is a plan view of half a cylinder bore 2 , The cylinder bore 2 is through a cylinder wall 3 limited. Radially outward extends around the cylinder wall 3 a coolant channel 5 , Two cylinder head screw threads are numbered 6. How out 1 it can be seen, the cylinder wall 3 According to the prior art, approximately cylindrical, ie the cylinder wall 3 has an approximately uniform thickness over the entire circumference.

The kinematics of a crank mechanism in a reciprocating internal combustion engine leads during a work cycle to multiple system change of a piston shaft of a piston on the cylinder wall 3 , in particular in the area of top dead center (TDC) and in the area below it in the direction of bottom dead center (TDC). An inclination of a connecting rod with respect to the piston presses after the top dead center, a shaft side of the piston to the cylinder wall. This shaft side of the piston is referred to as the pressure side, the opposite side of the shaft as a counter-pressure side. An offset of a piston pin axis to the piston longitudinal axis (desalination) changes the bearing behavior of the piston during the side change and thus influences the resulting forces and impact pulses on the cylinder wall crucial. By calculating the piston movement, the position and size of the offset to the piston longitudinal axis can be optimized and thus significantly reduce the piston running noise and the already mentioned cavitation danger in the coolant jacket on the cylinder wall.

However, this Desachsierung are set clear limits, especially in the use of steel pistons in a light metal crankcase, due to the different thermal expansion coefficients of steel and light metal, such. B. an aluminum-silicon alloy.

2 shows a plan view of an inventive crankcase 1 , Shown again is a half cylinder bore 2 passing through the cylinder wall 3 is limited. Also this cylinder wall 3 is through a coolant channel 5 surround. Two cylinder head screw threads are also numbered 6.

Also in the inventive design of the crankcase 1 has the piston, not shown by the already described kinematics in the crank mechanism on a pressure side, with which he in the area of top dead center (TDC) in the direction of bottom dead center (UT) an increased surface pressure on the cylinder wall 3 exercises. According to the invention it is therefore proposed that the cylinder wall 3 in the area of increased surface pressure on the outside of the cylinder bore 2 lying side of a material reinforcement 4 having. By this embodiment of the invention, the cylinder head screw thread 6 in crankcases 1 in closed-deck design advantageously close to the cylinder wall 3 be arranged, bringing a significant load increase of the crankcase 1 can be displayed at no extra cost in production and assembly.

The material reinforcement 4 preferably extends over 0 ° to 90 ° crank angle in height (piston stroke from TDC in the direction of UT (bottom dead center)) and has a thickness between 50% and 150% of the thickness of the cylinder wall. In addition, the material reinforcement 4 preferably extends over 30 ° to 120 ° radially around the cylinder bore 2 around, wherein the transition to the cylindrical part is preferably carried out running. In a further development of the invention, the cylinder bore 2 preferably a coating, more preferably this is an extremely seal-resistant LDS coating (arc wire tips).

The crankcase is preferred 1 made of a light metal, such as. As an aluminum-silicon alloy, especially when using steel pistons due to the different thermal expansion coefficients of aluminum and steel.

In a preferred embodiment, the pressure side of the piston is arranged on the outlet side of the reciprocating internal combustion engine, but also an inlet-side arrangement is possible.

For a simple and inexpensive production is the material reinforcement 4 manufactured in one piece with the same material as the crankcase. In a more elaborate and cost-intensive variant could also be a Eingießteil, for example made of steel use. As a manufacturing process, a low-pressure casting or die casting or sand casting and a 3-printing process can be used.

Definition pressure side: Due to the inclination of the connecting rod in the area of the TDC with respect to the cylinder axis, the piston is loaded laterally. The side on which the piston rests during the expansion stroke is called the pressure side.

Definition of back pressure side: The side on which the piston does not touch during the expansion stroke is called the back pressure side and is located opposite the pressure side.

It is thus inventively the thickening (material reinforcement 4 ) of the cylinder wall 3 0 ° to 90 ° crank angle high from TDC towards UT, with a thickness between 50% and 150% of the thickness of the cylinder wall 3 and an extent between 30 ° to 120 ° radially around the cylinder wall 3 around). For further minimization of wear of the cylinder wall 3 Furthermore, a coating, in particular an LDS coating, is proposed on the piston running surface.

LIST OF REFERENCE NUMBERS

1.

crankcase

Second

bore

Third

cylinder

4th

material gain

5th

Coolant channel

6th

Cylinder head screw thread

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• US 4461247 [0002]
• DE 102012204805 A1 [0005]

Claims (9)

Crankcase (1) for a reciprocating internal combustion engine, which has at least one cylinder bore (2) with a cylinder wall (3) for Hubbeweglichen leadership of a piston, in particular a steel piston, which is operatively connected via a connecting rod with a crankshaft, wherein the piston is a Pressure side, with which he exerts an increased surface pressure on the cylinder wall (3) in the region of a top dead center (TDC), characterized in that the cylinder wall (3) in the region of increased surface pressure on the outside of the cylinder bore (2) lying side a material reinforcement (4). Crankcase after Claim 1 , characterized in that the material reinforcement (4) extends from TDC over 0 ° to 90 ° crank angle in the direction of a bottom dead center (UT) in height. Crankcase after Claim 1 or 2 , characterized in that the material reinforcement (4) is between 50% and 150% of the thickness of the cylinder wall. Crankcase after one of Claims 1 to 3 Characterized in that the reinforcing material (4) extends over 30 ° to 120 ° radially around the cylinder bore (2) around. Crankcase after one of Claims 1 to 4 , characterized in that the cylinder bore (2) has a coating. Crankcase after Claim 5 , characterized in that the coating is an LDS coating (electric arc wire spraying). Crankcase after one of Claims 1 to 6 , characterized in that the crankcase (1) is made of a light metal. Internal combustion engine according to one of Claims 1 to 7 , characterized in that the pressure side of the piston is arranged on the outlet side. Internal combustion engine according to one of Claims 1 to 8th , characterized in that the material reinforcement (4) in one piece and of the same material with the crankcase (1).

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