Piston and cylinder of an internal combustion engine and internal combustion engine

Abstract

To create a new type of piston of a cylinder of an internal combustion engine, a cylinder of an internal combustion engine, and an internal combustion engine.SOLUTION: A piston (12) of a cylinder (10) of an internal combustion engine includes: an upper, or front, piston crown (14); a radially outer surface (13); grooves (16a, 16b, 16c) formed on the radially outer surface (13); and piston rings (17a, 17b, 17c) arranged in the grooves (16a, 16b, 16c). The radially outer surface (13) forms a top land (18) between the piston crown (14) and the uppermost, or frontmost, groove (16a) of the piston (12), and the top land (18) carries a non-abrasion-proof coating (22).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a piston for a cylinder of an internal combustion engine, to a cylinder for an internal combustion engine, and to an internal combustion engine. [Background technology]

[0002] From DE 10 200 03 133 A1 a piston for a cylinder of an internal combustion engine is known, which is guided in a cylinder liner so that it can move up and down. A flame ring is arranged in a recess in the cylinder liner. A groove is introduced in the radially outer surface of the piston, which receives the piston ring. Between the front or upper piston crown of the piston and the top or frontmost groove of the piston, the radially outer surface of the piston forms a so-called upper crest, and the flame ring of the cylinder liner serves to scrape off deposits, particularly in the region of the upper crest, from the radially outer surface of the piston.

[0003] Between the radially outer surface of the piston, i.e. the upper crest, and the flame ring, a clearance is required to allow undisturbed movement of the piston in the cylinder liner. In this clearance between the piston and the flame ring, a so-called dead volume is formed, in which the fuel mixture that does not participate in the combustion inefficiently can collect. In order to reduce the dead volume and thus increase the efficiency of the engine, according to the prior art, the clearance between the piston and the flame ring has been selected to be as small as possible. This requires high manufacturing tolerances.

[0004] From DE 10 200 03 13 A1 it is known to draw the piston crown axially backwards at its radially outer edge in order to reduce the dead volume. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] DE 10 2013 009 415 A1 Summary of the Invention [Problem to be solved by the invention]

[0006] Starting from this, the invention is based on the object of creating a new type of internal combustion engine cylinder piston, an internal combustion engine cylinder and an internal combustion engine. [Means for solving the problem]

[0007] This object is achieved by a piston according to claim 1. According to the invention, the upper crown of the piston carries a non-abrasion-proof coating.

[0008] According to the invention, it is proposed that the piston is provided with or carries a soft, non-wear-resistant coating in the region of the upper crest, which can be locally removed during local contact between the upper crest of the piston and the frame ring that develops during operation, so as to set the required operational gap between the piston and the frame ring precisely, i.e. without compromising the high manufacturing tolerances. By using a non-wear-resistant coating, the dead volume between the piston and the frame ring can be minimized and the efficiency of the engine is increased.

[0009] Preferentially, the non-wear resistant coating is composed of resin-bonded graphite, which is particularly preferred for establishing the operational clearance between the piston and the frame ring by localized wear of the coating during engine operation.

[0010] According to a further development of the invention, the non-wear-resistant coating has a thickness between 0.02 mm and 0.2 mm, preferentially between 0.05 mm and 0.15 mm, such a thickness of the non-wear-resistant coating being particularly preferred for establishing the operational clearance between the piston and the flame ring during engine operation.

[0011] A cylinder according to the invention is defined in claim 10 and an internal combustion engine according to the invention is defined in claim 11.

[0012] Preferred further developments of the invention emerge from the dependent claims and the following description.Exemplary embodiments of the invention are explained in more detail with the aid of the drawings, but without being limiting thereto. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view in an excerpt form of a first cylinder according to the invention of an internal combustion engine according to the invention; [Diagram 2] 2 shows a cross-sectional view in an excerpt form of a second cylinder according to the invention of an internal combustion engine according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention relates to an internal combustion engine, which comprises at least one cylinder.

[0015] 1 shows an excerpt of a cylinder 10 of an internal combustion engine according to the invention according to a first exemplary embodiment of the invention in the region of a cylinder liner 11 and a piston 12 guided in said cylinder liner 11 so as to be movable up and down. The piston 12 has a radially outer surface 13 and a front or upper piston crown 14, in which a central valley 15 can be introduced. On its radially outer surface 13, the piston 12 is provided with grooves 16a, 16b and 16c. Piston rings 17a, 17b, 17c are inserted into these grooves 16a, 16b and 16c of the piston 12. The two upper piston rings 17a, 17b are called compression rings and the lower piston ring 17c is called oil scraper ring.

[0016] The portion of piston 12 that extends between piston crown 14 and the top or frontmost groove 16a of piston 12 is referred to as upper crest 18. The distance between the top or frontmost groove 16a of piston 12 and piston crown 14c is referred to as upper crest height 18h of upper crest 18.

[0017] The cylinder liner 11 receives a flame ring 19. The flame ring 19 is inserted into a recess 20 of the cylinder liner 11. During operation, the piston 12 is cleaned in the region of its upper crest 18 with the aid of the flame ring 19. In particular, the flame ring 19 serves to scrape off deposits such as coke from the radially outer surface 13 of the piston 12, for example in the region of the upper crest 18 and thus in the region of the upper crest height 18h.

[0018] In the exemplary embodiment shown in Fig. 1, the outside diameter of the radially outer surface 13 conically decreases in the region of the upper crest 18 in the direction of the piston crown 14 from the front or uppermost groove 16, at least in a certain area. Between the upper crest 18 and the flame ring 19, a free space 21 is formed, which defines the gap between the flame ring 19 and the upper crest 18 of the piston 12. In this free space 21, fuel that is inefficiently combusted during engine operation can collect. For this reason, this free space 21 is also referred to as dead volume.

[0019] In order to achieve low manufacturing tolerances and increase the efficiency of the internal combustion engine while still keeping the dead volume 21 as small as possible, the upper crown 18 carries a non-wear resistant coating 22 on its radially outer side.

[0020] This relatively soft, non-wear resistant coating 22 is removable during localized contact between the upper ridge 18 of the piston 12 and the frame ring 19 to minimize the clearance required for operation between the upper ridge 18 of the piston 12 and the frame ring 19 during engine operation, which increases engine efficiency.

[0021] The non-wear resistant coating 22 is preferentially a coating made of resin-bonded graphite.

[0022] The piston 12 is preferentially an assembled piston consisting of a lower piston part, not shown, and an upper piston part, both of which may consist of steel or cast iron, in particular ductile cast iron. It is also possible to use light metals.

[0023] The non-wear resistant coating 22 is made of a softer material than the material of the lower piston portion and the upper piston portion, and is further made of a softer material than the frame ring 19 and the cylinder liner 11.

[0024] Further properties of the non-wear resistant coating 22 are temperature resistance up to 250°C, resistance to impact with fuels and lubricants, and good adhesion / bonding. The hardness of the coating 22 is preferably in the range of 10-50 HB (Brinell). Soft materials such as resin-bonded graphite or heat-resistant plastics meet these property requirements.

[0025] The non-wear-resistant coating 22, preferentially made of resin-bonded graphite, preferentially has a thickness between 0.02 mm and 0.2 mm, preferably between 0.05 mm and 0.15 mm.

[0026] In the exemplary embodiment of Figure 1, the non-wear-resistant coating 22 is applied to the upper crest 18 in a region that starts from the top or frontmost groove 16a and tapers conically in the direction of the piston crown 14. The coating 22 is applied to this region over the entire axial extent or over the entire axial length of the region, whereby the coating 22 in Figure 1 terminates in the region of the piston crown 14.

[0027] In contrast, FIG. 2 shows a variation of the invention in which the non-wear resistant coating 22 is designed to be shorter and terminates at a predetermined distance from the piston crown 14.

[0028] Preferentially, the piston 12 according to the invention is an oil-cooled piston.

[0029] The invention does not only relate to such a piston 12, but also to a cylinder 10 with a cylinder liner 11 and a piston 12 according to the invention, and also to an internal combustion engine having at least one, and preferentially several, such cylinders 10.

[0030] With the present invention, it is possible to improve engine efficiency, namely by reducing the dead volume between the frame ring 19 and the upper ridge 18 .

[0031] The invention can be used both in diesel internal combustion engines, spark ignition gas engines and dual fuel engines, i.e. in two-stroke internal combustion engines and also in four-stroke internal combustion engines. The invention can be used especially in pistons of large engines such as diesel or gas engines or diesel-gas engines in marine applications, the outside diameter of which is especially in the range from 100 mm to 600 mm. [Explanation of symbols]

[0032] 10 Cylinders 11 Cylinder liner 12 Piston 13 Surface 14 Piston crown 15 Piston valley 16a Groove 16b Groove 16c groove 17a Piston ring 17b Piston ring 17c piston ring 18 Upper mountain section 18h Upper peak height 19 Frame Ring 20 Recess 21 Free Space / Waste Volume 22 Coating

Claims

1. A piston (12) of a cylinder (10) of an internal combustion engine, an upper or forward piston crown (14) and a radially outer surface (13); said radially outer surface (13) is formed with grooves (16a, 16b, 16c) in which piston rings (17a, 17b, 17c) are disposed; Between the piston crown (14) and the top or frontmost groove (16a) of the piston (12), the radially outer surface (13) defines an upper ridge (18); The upper ridge (18) carries a non-wear resistant coating (22), the non-wear resistant coating (22) being configured to be partially removable by localized contact between the upper ridge (18) and a frame ring (19) housed in a cylinder liner (11) of the cylinder (10) during operation of the piston (12).

2. 2. The piston (12) of claim 1, wherein the non-wear resistant coating (22) comprises resin-bonded graphite.

3. 3. The piston (12) of claim 1 or 2, characterized in that the non-wear resistant coating (22) has a thickness of 0.02 mm to 0.2 mm.

4. 4. The piston (12) of claim 3, wherein the non-wear resistant coating (22) has a thickness of 0.05 mm to 0.15 mm.

5. 5. The piston (12) of claim 1, wherein the non-wear resistant coating (22) extends over the entire axial length of the upper ridge (18).

6. 5. The piston (12) of claim 1, wherein the non-wear resistant coating (22) extends over a partial area of ​​the axial length of the upper ridge (18).

7. The non-wear resistant coating (22) the upper ridge portion (18) extends in the longitudinal direction of the piston crown (14) over a partial region of the axial length of the upper ridge portion (18) as viewed from an end of the upper ridge portion (18) that is remote from the piston crown (14); and 7. The piston (12) of claim 6, terminating a predetermined distance from said piston crown (14).

8. 8. The piston (12) of any one of claims 1 to 7, wherein the piston comprises a lower piston portion and an upper piston portion connected to the lower piston portion, the upper ridge (18) being formed on the upper piston portion, the upper piston portion being constructed from steel or cast iron.

9. 9. The piston (12) of any one of claims 1 to 8, wherein the piston is oil cooled.

10. A cylinder (10) for an internal combustion engine, comprising: A cylinder liner (11), wherein a recess (20) of the cylinder liner (11) accommodates a frame ring (19); a piston (12) guided so as to be vertically movable within the cylinder liner (11); It has The cylinder (10), characterized in that the piston (12) is in accordance with any one of claims 1 to 9.

11. An internal combustion engine, characterized in that it comprises at least one cylinder (10) according to claim 10.

Images