DE102012018330A1 - Crankshaft for use in crankcase of internal combustion engine e.g. in-line engine, for vehicle, has roller bearing comprising ring molded in crankshaft and provided for supporting crankshaft, where crankshaft is made from cast material - Google Patents

Abstract

The crankshaft (1) has a roller bearing (5) comprising an inner ring (5.1) and provided for rotatably supporting the crankshaft. The inner ring is molded in the crankshaft, where the crankshaft is made from cast material. The roller bearing is designed as a connecting rod bearing (2) and provided with an outer ring (5.2) that comprises an outer-side surface profile and/or outlining. A crankshaft flange (3) and/or an output wheel (4) is arranged at the crankshaft in a form-fit and firmly-bonded manner, where the roller bearing is arranged at a front side of the crankshaft. An independent claim is also included for a method for manufacturing of a crankshaft.

Description

The invention relates to a crankshaft for arrangement in a crankcase of an internal combustion engine, which is rotatably mounted by means of rolling bearings, wherein the rolling bearings each have at least one inner ring.

From the DE 10 2009 041 978 A1 An internal combustion engine for a vehicle is known. The internal combustion engine has a motor housing, in which a crankshaft is mounted by means of at least one sliding bearing. The bearings arranged on each end face of the crankshaft are roller bearings.

The invention has for its object to provide a comparison with the prior art improved crankshaft for arrangement in a crankcase of an internal combustion engine and a method for producing such a crankshaft.

The object is achieved with respect to the crankshaft by the in claim 1 and in terms of the method for production by the features specified in claim 7.

Advantageous embodiments of the invention are the subject of the dependent claims.

A crankshaft for arrangement in a crankcase of an internal combustion engine is rotatably supported by means of a different number of rolling bearings, wherein the rolling bearings each have at least one inner ring. According to the invention, the crankshaft is formed from a cast material and the inner rings of the rolling bearings are cast into the crankshaft.

Since the crankshaft is formed from a casting material, in particular cast iron steel, and the inner rings of at least the roller bearings are cast into the crankshaft, a cost-effective solution for producing such a crankshaft is advantageously provided. This in turn makes it possible to produce a comparatively inexpensive engine for a vehicle. Thus, it is still possible to realize lower costs in such an engine concept.

In addition, the crankshaft is more resistant compared to a crankshaft formed entirely of cast material, since the cast-in inner rings made of bearing steel into the crankshaft, the same less wear occurs or allows operation with bearings only.

Bearings experience fluid friction during operation. Fluid friction occurs when a permanent lubricating film, such as oil, forms between the sliding surfaces. At low speeds occur in plain bearings considerable friction losses due to so-called mixed friction. The mixed friction can occur with insufficient lubrication or at the beginning of the movement of two friction partners with lubrication. The sliding surfaces touch at points. The wear is higher than with pure liquid friction.

Rolling bearings cause less frictional losses in comparison to slide bearings, since the fluid friction is substituted by a rolling friction. The life of the bearing can be extended by applying lubricating oil and the rolling friction occurring in the bearing can be further reduced. Compared to the plain bearing, the required amount of lubricating oil is lower. Thus, less oil must be moved in an oil pump and the energy requirement of the oil pump is reduced. Through the use of two bearings at the front and rear end, the crankshaft is no longer in the rest position in contrast to a conventional, fully sliding bearing crankshaft in the bearings. As a result, the so-called breakaway torque of such a crankshaft is reduced compared to conventional, fully slide-mounted crankshafts.

Thus, a low-friction operation is also possible in the starting phase of the internal combustion engine.

The resulting from the reduced friction lower energy consumption during starting processes of internal combustion engines can reduce pollutant and / or CO ₂ emissions in so-called start / stop systems, which stop the engine at a stop of the vehicle. In addition, a high wear caused by numerous start / stop operations can be significantly reduced.

The inner rings of the respective rolling bearing are cast, whereby advantageously lower rolling bearing diameter and thus lower friction losses are possible. As a result, concepts are also possible in a limited space environment.

Furthermore, the invention relates to a method for producing such a crankshaft.

Preferably, cost-effective cast iron steels are used as the crankshaft material, higher quality steel being used for functionally relevant points of the crankshaft, and less high-grade cast iron steel being used for non-functional surfaces.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 1 is a schematic sectional view of a sliding bearing crankshaft not according to the invention;

2 schematically a sectional view of a non-inventive forged crankshaft and

3 schematically a sectional view of a cast crankshaft with cast-in inner rings.

Corresponding parts are provided in all figures with the same reference numerals.

1 shows a sectional view of a crankshaft not according to the invention 1 for arrangement in a crankcase, not shown, of an internal combustion engine, in particular for a vehicle.

The crankshaft 1 is formed from a casting material and / or forged and rotatably mounted in the crankcase exclusively by means of a plurality of plain bearings. These bearings are supplied during engine operation with oil, which is promoted during engine operation by an oil pump, not shown. In plain bearings, fluid friction occurs during operation. The liquid friction occurs when between the sliding surface of the sliding bearing and the sliding surface of the crankshaft 1 a permanent lubricating film, for example of oil forms. At low speeds occur in plain bearings considerable friction losses due to so-called mixed friction. The mixed friction may be due to insufficient lubrication or to the beginning of crankshaft movement 1 occur in the plain bearing. In this case, the sliding surface of the sliding bearing and the sliding surface of the crankshaft touch 1 selectively. The wear is higher with this mixed friction than with pure liquid friction.

In the rest position, the internal combustion engine is not pressurized by the oil pump with oil and thus the bearings are not supplied with oil. The crankshaft 1 decreases due to this lack of oil and due to gravity in the direction of the sliding surface of the plain bearing from. This results in a contact of the sliding surface of the crankshaft 1 with the sliding surface of the sliding bearing on at least one contact surface. At this contact surface of the lubricating film of the sliding bearing is interrupted and it occurs on the above-described mixed friction. The mixed friction increases the wear of the sliding surface of the sliding bearing and the sliding surface of the crankshaft 1 and the mixed friction results in a large breakaway torque of the crankshaft 1 at engine start. The high breakaway torque requires greater drive power of a starter of the internal combustion engine, not shown. Especially in so-called start / stop systems, which stop the engine at a stop of the vehicle, this leads to a shortening of the life of the starter.

The crankshaft 1 has a connecting rod bearing 2 on, each front side a crankshaft flange 3 and / or a driven wheel 4 on the crankshaft 1 are arranged against rotation. crankshaft 3 and / or driven wheel 4 are preferably by means of a conical centering on the crankshaft 1 arranged, whereby a fitting accuracy is increased and assembly inaccuracies can be avoided.

Preferably, the crankshaft flange 3 and the output gear 4 cohesively on the crankshaft 1 fastened, wherein the cohesive attachment may be formed by a conventional laser welding operation.

2 also shows a crankshaft 1 According to the prior art, which is an elaborately made forging shaft, which is made of a bearing steel and at least thereby is relatively expensive. In addition, the forging process is a complex machining process for the production of the crankshaft 1 ,

To a relatively inexpensive solution for the production of a crankshaft 1 to indicate the arrangement in a crankcase of an internal combustion engine, it is provided that the crankshaft 1 is cast from a cast material, in particular cast iron steel, as in 3 is shown in more detail.

The crankshaft 1 is by means of a plurality of rolling bearings 5 arranged in the crankcase, wherein on each end side of the crankshaft 1 and between the conrod bearings 2 , Roller bearing 5 are arranged.

The connecting rod bearings 2 the crankshaft 1 are also as rolling bearings 5 educated. Such a rolling bearing 5 includes a rotationally symmetrical inner ring 5.1 and a rotationally symmetrical outer ring 5.2 , between which a number of rolling elements 5.3 is arranged. These rolling elements 5.3 are preferably held by means of a cage, not shown. At the rolling bearings 5 These are, for example, conventional needle roller bearings, ball bearings and / or roller bearings.

For the relatively inexpensive production of the crankshaft 1 are the inner rings 5.1 the rolling bearing 5 in the crankshaft 1 cast. In this case, the respective inner ring 5.1 by means of a crankshaft steel, which is also suitable in particular as bearing steel, during the casting process of the crankshaft 1 poured into the same, so that the inner rings 5.1 in the crankshaft 1 are integrated. For example, the respective inner ring 5.1 from bearing steel, such as. Hardenable Cr-alloyed steel (1.3505) or higher alloyed X65Cr13 (1.4037), X30CrMoN15-1 (1.4108) or the like. In addition, it can be provided that a corresponding shaft portion of the crankshaft 1 as inner ring 5.1 is trained. The direct formation of the corresponding shaft portion of the crankshaft 1 as inner ring 5.1 of the respective rolling bearing 5 allows lower rolling bearing diameter and thus lower friction losses.

The crankshaft 1 itself is cast from a comparatively inexpensive cast iron steel, in particular the inner rings 5.1 , as described above, are formed of a higher quality steel.

The respective outer ring 5.2 the rolling bearing 5 has at least on its outer side, for example, a surface profiling, so that it centered and against rotation as part of the respective rolling bearing 5 is held. Such a surface profiling may be formed, for example, as roughening, toothing, corrugation and / or groove. Also, the outer ring 5.2 the rolling bearing 5 , which are on the outside of the crankshaft 1 are arranged, have a contouring, by means of which a manufacturing-related shaft misalignment can be compensated in the crankcase.

The along the crankshaft 1 by means of the inner rings 5.1 , the rolling element 5.3 and the outer rings 5.2 formed bearings 5 cause less energy loss compared to plain bearings, as in a fluid friction of the plain bearings by a rolling friction in the rolling bearings 5 is substituted. The life of the respective rolling bearing 5 can be prolonged by an application of lubricating oil and the rolling friction occurring in the rolling bearing 5 can be further reduced thereby.

Furthermore, a crown of the rolling elements 5.3 of the respective rolling bearing 5 be increased in comparison.

The rolling bearings 5 cause less energy losses compared to the plain bearings, as the fluid friction of the plain bearing by rolling friction in the rolling bearing 5 is substituted. The life of the rolling bearing 5 can be prolonged by an application of lubricating oil and the rolling friction occurring in the rolling bearing 5 can be further reduced thereby. Compared to the plain bearing is the required amount of lubricating oil of the bearing 5 lower. Thus, less oil must be moved in an oil pump and the energy requirement of the oil pump is reduced.

Because of the crankshaft 1 is made of cast iron steel and the inner rings 5.1 the rolling bearing 5 when manufacturing the crankshaft 1 poured into this is a relatively inexpensive solution for the production of a crankshaft 1 specified. In addition, the inner rings 5.1 an operational lower wear on.

Such a trained crankshaft 1 is comparatively low in wear and can be used in both series and V engines and their mixed forms.

LIST OF REFERENCE NUMBERS

1

crankshaft

2

connecting rod bearing

3

crankshaft

4

output gear

5

roller bearing

5.1

inner ring

5.2

outer ring

5.3

rolling elements

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

• DE 102009041978 A1 [0002]

Claims (8)

Crankshaft ( 1 ) for arrangement in a crankcase of an internal combustion engine, which by means of rolling bearings ( 5 ) is rotatably mounted, wherein the rolling bearing ( 5 ) each have at least one inner ring ( 5.1 ), characterized in that the crankshaft ( 1 ) is formed from a casting material and the inner rings ( 5.1 ) of rolling bearings ( 5 ) in the crankshaft ( 1 ) are poured. Crankshaft ( 1 ) according to claim 1, characterized in that the crankshaft ( 1 ) by means of frontally arranged roller bearings ( 5 ) is rotatably mounted. Crankshaft ( 1 ) according to one of the preceding claims, characterized in that at least one connecting rod bearing ( 2 ) of the crankshaft ( 1 ) as rolling bearings ( 5 ) is formed and the inner rings ( 5.1 ) as a tome bearing ( 5 ) trained connecting rod bearings ( 2 ) in the crankshaft ( 1 ) are poured. Crankshaft ( 1 ) according to one of the preceding claims, characterized in that between the front side arranged roller bearings ( 5 ) at least one further bearing for supporting the crankshaft ( 1 ) is formed in the crankshaft housing, wherein the bearing is a rolling bearing ( 5 ). Crankshaft ( 1 ) according to one of the preceding claims, characterized in that an outer ring ( 5.2 ) of the rolling bearing ( 5 ) has a surface profiling and / or contouring at least on the outside. Crankshaft ( 1 ) according to one of the preceding claims, characterized in that a crankshaft flange ( 3 ) and / or a driven wheel ( 4 ) positively and cohesively on the crankshaft ( 1 ) are arranged or is. Method for producing a crankshaft ( 1 ) according to one of claims 1 to 6, characterized in that the crankshaft ( 1 ) is formed from a casting material and the inner rings ( 5.1 ) of rolling bearings ( 5 ) in the crankshaft ( 1 ) are poured. A method according to claim 7, characterized in that the driven wheel ( 4 ) by means of a thermal joining process on the crankshaft ( 1 ) is arranged.

Images