DE102017213896A1 - internal combustion engine - Google Patents

Abstract

The invention relates to an internal combustion engine (1) with at least one cylinder (3) having a cylinder surface (2) and a piston (4) which carries out a stroke movement in said cylinder. The piston (4) has a piston head (5) with a ring section (10) receiving an oil scraper ring (12) and a piston skirt (6) with a piston running surface (7). According to the invention, in an end section of the piston skirt (6) facing the oil scraper ring (12), an oil collecting channel (13) which extends in the circumferential direction and is open at least on one side is arranged below the oil scraper ring (12) such that during a downward stroke of the piston (FIG. 4) collected by the Ölabstreifringes (12) of the cylinder surface (2) stripped oil in the oil collection channel (13). Between the oil collection channel (13) and the piston running surface (7) extends a drain hole (20).

Description

The invention relates to an internal combustion engine having at least one cylinder having a cylinder surface and having a piston in this a lifting movement, which comprises a ring portion with a Ölabstreifring and a piston skirt with a piston tread.

In an internal combustion engine of the type mentioned, the free area of the cylinder running surfaces below the piston is wetted with oil from the crankcase and the piston cooling. This oil is available to the piston skirt in the downstroke of the piston, so that the piston runs predominantly in the hydrodynamic friction state. In this case, the oil collects by the wiping action of the oil scraper ring in the upper part of the piston skirt immediately below the Ölabstreifringes. However, it proves to be problematic that this oil moves away from this area at the beginning of the upstroke. Although the piston runs in a hydrodynamic friction state as a result of the relatively low loads in the entire upstroke. Due to the higher loads in the expansion phase, ie from about ZOT (ignition upper dead center) to just before about 90 ° crank angle to ZOT, however, the mixed friction increases due to the existing lack of lubrication between the cylinder surfaces and the running surfaces of the piston skirt.

To reduce the friction between the treads has already been thought to increase the cold play of the piston. However, this increases the piston tilt and the impact pulse against the cylinder wall. This reduces the effect of the oil scraper ring and the acoustics deteriorate.

The DE 35 06 399 A1 discloses a piston in which a lubrication groove, which is arranged above the tread associated with the pressure side, is connected via a bore to a cooling channel arranged in the region of a ring portion of the piston. The lubricating groove is supplied with lubricating oil from the cooling channel in about the second half of the downstroke of the piston. However, the lubrication causes the downstroke no hydrodynamic oil film can build up, because the oil from the relatively large opening expires immediately and can build up no oil pressure. A hydrodynamic floating of the piston on a lubricating oil film, as it is desirable given the prevailing maximum frictional forces, can not be done.

From the DE 10 2011 012 685 A1 A piston is also known in which a cooling channel arranged in the region of a ring section of the piston is connected via a bore to a comparatively large lubricating pocket arranged in the lower region of a running surface of the piston skirt.

In the DE 10 2011 119 525 A1 a piston is described in which dripping oil is passed from a arranged in the region of the ring belt cooling channel via a groove in the direction of a tread of a piston skirt.

The invention has for its object to perform an internal combustion engine of the type mentioned in such a way that lubrication of the piston is optimized in the region of the treads.

This object is achieved with an internal combustion engine according to the features of claim 1. The dependent claims relate to particularly expedient developments of the invention.

According to the invention, therefore, an internal combustion engine is provided with at least one cylinder surface having a cylinder and a piston running in this stroke, which comprises a ring portion with a Ölabstreifring and a piston skirt with a piston tread, wherein in an oil ring facing the end portion of the piston skirt a in Circumferentially extending unilaterally open oil collection channel is arranged below the Ölabstreifringes that collects in a downward stroke of the piston by the Ölabstreifringes stripped from the cylinder surface oil in the oil collection channel, and wherein at least one outgoing from the oil collection channel and opening into the piston running surface drain hole is provided. The arrangement of the formed as an oil reservoir oil collection channel immediately below the Ölabstreifringes ensures that at each stage of the reciprocating motion of the piston, in particular during the upstroke, sufficient oil is stored in the oil collection channel. The oil stripped off the cylinder surface during the downstroke of the piston and trapped in the oil collection passage runs continuously over the drain bore throughout the subsequent upward stroke of the piston and wets the piston and cylinder surface. The elapsed between 90 ° crank angle before the ZOT and ZOT oil is the piston skirt and the piston and cylinder surface in the first half of the expansion phase between ZOT and 90 ° crank angle to ZOT available to a lack of lubrication and consequent mixed friction between the cylinder surface and prevent the piston tread. By the invention, an optimized lubrication of the piston skirt or the running surfaces of the cylinder and the piston can be provided, since the oil is supplied at the right time in the right place in the correct dosage.

Here, the drain hole is formed inclined so that a piston central axis and the drain hole include an acute angle. Advantageously, the acute angle between the piston center axis and a central axis of the drain hole or between the piston center axis and at least a portion or - section of the drain hole limiting wall surface of the piston extends. The partial region or section is preferably a wall surface of the drainage bore facing away from the piston crown, along which the oil can flow out of the oil collection passage in the direction of the piston running surface.

It proves to be particularly advantageous that the oil collection channel extends symmetrically on both sides of a plane perpendicular to the pin axis and extending through the piston center axis plane. Here, the oil collection channel can either extend over a partial circumference of the piston skirt or completely surround the piston. Preferably, the oil collection channel is adapted to the dimension of the piston running surface in the circumferential direction and extends over the entire width of the piston skirt. This ensures that there is a sufficient amount of oil in the oil collection channel to ensure drainage of oil from the drain hole throughout the upstroke of the piston and the resulting optimum wetting of the treads.

This effect is also supported by the fact that the drainage hole is arranged in the plane perpendicular to the pin axis and running through the piston center axis. By such a central arrangement of the drain hole in the oil collection channel both an inflow into the drain hole as well as an outflow in the area of the piston treads is optimized.

In a filled oil collection channel, a continuous supply of oil for the piston skirt or for the piston running surface is also ensured by the fact that one of the drain hole adjacent bottom region of the oil collection channel has an inclination in the direction of the drain hole. In a drain hole arranged centrally in the oil collection channel, the channel sections of the oil collection channel which extend on both sides are provided with an inclination in the direction of the drainage bore. As a result, the oil in the oil collection channel always flows in the direction of the drain hole

In this case, it proves expedient that an inlet opening of the drain hole in the bottom region of the oil collection channel and an outlet opening of the drain hole in the piston tread is arranged. This ensures that the oil in the oil collection channel also reaches the outlet opening in the region of the piston running surface.

A further optimization of the lubrication can also be achieved by providing two or more drainage holes between the oil collection channel and the piston running surface. As a result, the dosage and the location of the oil supply can be adapted to the respective requirements.

The drain hole is formed in its longitudinal extent as a circumferentially closed bore with an inlet and an outlet opening arranged in the end portions. However, it has proved to be particularly advantageous that a cross-sectional area of the drainage bore, starting from the inlet opening, widens in the direction of the outlet opening, in particular continuously. By this diffuser-like design of the drain hole, the pressure increases and decreases the flow velocity of the oil in the region of the outlet opening, so that an optimal oil supply or wetting of the piston and cylinder surface can be ensured. The drainage hole may, for example, have a circular or an oval cross-section. A design as a slot is conceivable.

A particularly expedient development of the invention is also characterized in that a fluidic connection is provided between the oil collection channel and a circumferential cooling channel arranged in the region of the ring section or the piston crown. This fluidic connection may for example be formed as a bore, which ensures that in the oil collection channel is a sufficient amount of oil for optimum lubrication of the piston skirt during the lifting movement of the piston is available.

A particularly advantageous embodiment of the invention is also provided in that the oil collection channel is formed by an undercut of a groove arranged in the piston skirt and extending in the direction of the piston center axis. The groove forms a recess in the piston skirt through which the oil scraped off the cylinder liner by means of the oil control ring penetrates into the groove. The undercut prevents drainage of the penetrated oil and also acts as an oil collection channel.

The supply of the oil which has penetrated into the groove to the undercut forming the oil channel is also assisted by the fact that a wall surface of the groove adjacent to the oil scraper ring is designed as a particularly linearly inclined or curved deflection surface. Here, the oil flows over the Deflection surface and is guided by inclination or curvature thereof directly into the undercut and collected there.

Another embodiment of the invention is characterized in that the ring portion of the piston is separated from the piston skirt by a circumferential annular recess. that the piston skirt is thermally decoupled. In a piston with a thermally decoupled piston skirt according to the invention the oil collection channel is arranged in a free end face of the piston skirt facing the ring part. The stripped from the oil control ring oil then passes through the annular recess to the upwardly open oil collection channel and is collected and collected in this.

The collection of the oil in the oil collection channel is also optimized in that a surface portion of the free end face of the piston skirt adjacent to the oil collection channel and facing the piston center axis has an inclination in the direction of the oil collection channel. As a result, the oil, which does not pass directly into the oil collection channel but onto the adjacent surface section, flows into the oil collection channel.

Another feature of the invention, which optimizes the collection of the stripped oil in the oil collection channel, is that a piston ring of the ring portion adjacent to the oil scraper ring and facing the piston skirt is formed as a guide surface inclined at least in sections in the direction of the free end surface of the piston skirt Piston center axis facing end portion of the guide surface forms a drip edge and a radial distance between the drip edge and the piston center axis is greater than or equal to a radial distance between the opening cross section of the oil collection channel bounding inner edge of the free end face of the piston skirt and the piston center axis. The stale during the downward stroke of the cylinder surface oil flows over the guide surface to the drip edge, which is located immediately above the opening of the oil collection channel. From the drip edge, the oil then drips or flows into the oil collection channel and is trapped in it.

In order to prevent leakage of the already located in the oil collection channel oil in the direction of the piston interior during the strokes of the piston, it is provided that one of the piston central axis facing inner wall surface of the oil collection channel is configured such that forms an undercut in the oil collection channel. Alternatively, the oil collection channel may also have a depth that is greater than the width in the radial extent.

• 1 eine Teildarstellung eines erfindungsgemäßen Verbrennungsmotors mit einem Kolben und einem Zylinder in einer zumindest teilweise geschnittenen Ansicht;
• 2 eine Teildarstellung des Verbrennungsmotors gemäß 1 in einer um 90° gedrehten Seitenansicht;
• 3 den in 2 abgebildeten Kolben des Verbrennungsmotors in einer Draufsicht;
• 4 eine vergrößerte Teildarstellung des Kolbens gemäß 2;
• 5 eine vergrößerte Teildarstellung des Kolbens gemäß 4;
• 6 eine weitere vergrößerte Teildarstellung des Kolbens gemäß 4;
• 7 eine vergrößerte Teildarstellung einer zweiten Ausführungsform eines Kolbens für den Verbrennungsmotor;
• 8 eine vergrößerte Teildarstellung des Kolbens gemäß Einzelheit VIII in 7;
• 9 eine Teildarstellung des Kolbens gemäß 7 in einer perspektivischen Ansicht;
• 10 eine Frontansicht des Kolbenhemdes gemäß 9 ohne eine äußere Mantelfläche des Kolbenhemdes;
• 11 eine entlang der Linie XI-XI in 10 geschnittene Teildarstellung des Kolbenhemdes in einer perspektivischen Ansicht;
• 12 bis Ölsammelkanäle mit unterschiedlich ausgestalteten Querschnittsformen. 14.

The invention allows numerous embodiments. To further clarify its basic principle, one of them is shown in the drawing and will be described below. This shows in

• 1 a partial view of an internal combustion engine according to the invention with a piston and a cylinder in an at least partially cut view;
• 2 a partial view of the internal combustion engine according to 1 in a rotated by 90 ° side view;
• 3 the in 2 pictured piston of the internal combustion engine in a plan view;
• 4 an enlarged partial view of the piston according to 2 ;
• 5 an enlarged partial view of the piston according to 4 ;
• 6 a further enlarged partial view of the piston according to 4 ;
• 7 an enlarged partial view of a second embodiment of a piston for the internal combustion engine;
• 8th an enlarged partial view of the piston according to the detail VIII in 7 ;
• 9 a partial view of the piston according to 7 in a perspective view;
• 10 a front view of the piston skirt according to 9 without an outer surface of the piston skirt;
• 11 one along the line XI - XI in 10 partial sectional view of the piston skirt in a perspective view;
• 12 to oil collection channels with differently designed cross-sectional shapes. 14 ,

Based on 1 to 6 Below is a first embodiment of an internal combustion engine according to the invention 1 briefly explained. The internal combustion engine 1 usually has several each a cylinder surface 2 having cylinders 3 on, in each of which a piston 4 performs a lifting movement. In 1 to 6 but is only a single cylinder 3 with a piston 4 shown.

The piston 4 includes a piston head 5 and a piston shirt 6 with a piston tread 7 , By a piston pin 8th is the piston 4 connected to a connecting rod, not shown. The piston head 5 has a piston chamber facing a combustion chamber 9 and a circumferential ring part 10 for receiving two piston rings 11 and an oil scraper ring 12 on.

In one of the ring part 10 facing end portion of the piston skirt 6 is immediately below the oil scraper ring 12 a unilaterally opened oil collection channel 13 arranged. This extends in the circumferential direction and symmetrically to both sides of a perpendicular to a pin axis 14 of the piston pin 8th spanned and by a the piston center axis 15 passed level 16 (see direction arrow in 3 ). The oil collection channel 13 is through an undercut one in the piston skirt 6 arranged and in the direction of the piston center axis 15 extending groove 17 formed, wherein the groove 17 a recess 18 in the piston shirt 6 or a lateral surface of the piston skirt 6 formed. One the oil scraper 12 adjacent wall surface of the groove 17 is as an inclined or curved deflection surface 19 designed.

Between the oil collection channel 13 and the piston tread 7 is a drain hole 20 provided, which in the direction perpendicular to the bolt axis 14 of the piston pin 8th spanned and through the piston center axis 15 passed level 16 is arranged and the oil collection channel 13 divided into two equal parts. Of course it is also possible that the drain hole 20 the oil collection channel 13 divided into two sections of different sizes. The drain hole 20 is inclined so that the piston center axis 15 and the drain hole 20 include an acute angle (α). Preferably, the drain hole 20 a linear slope course. There is an inlet opening 21 the drain hole 20 in a floor area 22 of the oil collection channel 13 and an outlet opening 23 the drain hole 20 directly in the piston tread 7 arranged. The floor area 22 of the oil collection channel 13 or the two sections of the oil collection channel 13 has a slope in the direction of the drain hole 20 or the inlet opening 21 on (see 10 ).

As in 4 to recognize, is the oil collection channel 13 also through a hole 24 with one provided for the piston cooling and in the region of the ring section 10 arranged circumferential cooling channel 25 connected. This allows oil from the cooling channel 25 in the oil collection channel 13 flow (see directional arrow 26 in 5 ).

Throughout the downstroke of the piston 4 this will be on the cylinder surface 2 of the cylinder 3 located oil through the oil scraper ring 12 stripped, passes through the recess 18 in the piston shirt 6 in the groove 17 , flows along the deflection surface 19 in the oil collection channel 13 and is caught and collected there (see directional arrow 27 in 5 ).

During the entire upstroke of the piston 4 this flows in the oil collection channel 13 collected oil then continuously through the drain hole 20 in the direction of the piston tread 7 and enters there through the arranged in this outlet opening 23 off (see directional arrow 28 in 5 ). Due to the inclination of the floor area 22 of the oil collection channel 13 The oil flows inside it in the direction of the inlet opening 21 the drain hole 20 , The slope of the drain hole 20 opposite the piston center axis 15 ensures a continuous drainage of oil from the oil collection channel 13 in the direction of the piston tread 7 ,

At the end of the upstroke of the piston 4 Part of the still occurs in the oil collection channel 13 located oil then by the inertial force upwards from the oil collection channel 13 out and flows along the deflection surface 19 through the recess 18 in the piston shirt 6 in the direction of the cylinder surface 2 and wet them (see directional arrow 29 in 6 ).

In the 7 to 14 a second embodiment of the invention is shown, wherein like reference numerals refer to the same components or elements. The piston 4 here is a thermal from the piston head 5 decoupled piston shirt 6 on. The thermal decoupling is effected by a circumferential annular recess 30 between the ring part 10 and the piston shirt 6 , Here is the oil collection channel 13 in one of the ring parts 10 facing free end face 31 the piston shirt 6 below the oil scraper ring 12 arranged. The oil collection channel 13 is as one in the free end face 31 introduced and in the direction of the piston head 5 or the ring part 10 open groove 32 educated. For guiding the oil scraper ring 12 from the cylinder surface 2 stripped oil is a the oil scraper 12 adjacent piston bar of the ring section 10 as one towards the free end face 31 the piston shirt 6 inclined guide surface 33 educated. One of the piston center axis forms 15 facing end portion of this guide surface 33 a drip edge 34 , wherein a radial distance between the drip edge 34 and the piston center axis 15 is greater than a radial distance between one the opening 35 of the oil collection channel 13 limiting inner edge 36 the free end face 31 the piston shirt 6 and the piston center axis 15 , This is the drip edge 34 just above the opening 35 of the oil collection channel 13 arranged so that the stripped oil along the guide surface 33 over the drip edge 34 through the opening 35 in the oil collection channel 13 flows and is collected there.

It is further provided that a the oil collection channel 13 adjacent and the piston center axis 15 facing surface section 37 the free end face 31 the piston shirt 6 a slope in the direction of the oil collection channel 13 having. As a result, oil flows, which in engine operation on the surface section 37 drips, in the oil collection channel 13 from.

Basically, different cross-sectional shapes of the groove 32 or the oil collection channel 13 conceivable. 8th and 11 to 14 show different embodiments of cross-sectional shapes of the oil collection channel 13 , 11 and 12 show an advantageous embodiments, according to which one of the piston center axis 15 facing inner wall surface 38 of the oil collection channel 13 is formed inclined or curved so that an undercut in the oil collection channel 13 formed. This can be during the strokes of the piston 6 an oil loss in the direction of the piston center axis 15 be reduced.

LIST OF REFERENCE NUMBERS

1

internal combustion engine

2

Cylinder surface

3

cylinder

4

piston

5

piston head

6

skirt

7

Piston tread

8th

piston pin

9

piston crown

10

ring belt

11

piston ring

12

Ölabstreifreifring

13

Oil collecting channel

14

pin axis

15

Piston central axis

16

level

17

groove

18

recess

19

deflecting

20

drain hole

21

inlet port

22

floor area

23

outlet

24

drilling

25

cooling channel

26

arrow

27

arrow

28

arrow

29

arrow

30

recess

31

free end face

32

groove

33

baffle

34

drip edge

35

opening

36

edge

37

surface section

38

inner wall surface

angle

(Α)

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 3506399 A1 [0004]
• DE 102011012685 A1 [0005]
• DE 102011119525 A1 [0006]

Claims (15)

Internal combustion engine (1) with at least one cylinder (3) having a cylinder surface (2) and with a piston (4) which carries out a lifting movement, which has a ring part (10) with an oil scraper ring (12) and a piston skirt (6) with a piston A piston running surface (7), wherein in a the oil scraper ring (12) facing the end portion of the piston skirt (6) extending in the circumferential direction at least unilaterally open oil collection channel (13) is arranged below the Ölabstreifringes (12), that in a downstroke of Piston (4) by means of the Ölabstreifringes (12) of the cylinder surface (2) scraped oil in the oil collection channel (13) collects, and wherein at least one of the oil collection channel (13) outgoing and in the piston running surface (7) emptying drain hole (20) is provided , Internal combustion engine (1) after Claim 1 , characterized in that the drainage bore (20) is formed inclined so that a piston central axis (15) and the drainage bore (20) form an acute angle (α). Internal combustion engine (1) according to Claims 1 or 2 , characterized in that the oil collecting channel (13) extends on both sides of a plane perpendicular to the pin axis (14) and through the piston center axis (15) extending plane (16) and / or that the drain hole (20) in a direction perpendicular to the pin axis ( 14) spanned and through the piston center axis (15) extending plane (16) is arranged. Internal combustion engine (1) according to at least one of the preceding claims, characterized in that one of the drain hole (20) adjacent bottom region (22) of the oil collection channel (13) has an inclination in the direction of the drain hole (20). Internal combustion engine (1) according to at least one of the preceding claims, characterized in that an inlet opening (21) of the drainage bore (20) in the bottom region (22) of the oil collection channel (13) and an outlet opening (23) of the drainage bore (20) in the piston tread ( 7) is arranged. Internal combustion engine (1) according to at least one of the preceding claims, characterized in that between the oil collecting channel (13) and the piston running surface (7) two or more drain holes (20) extend. Internal combustion engine (1) according to at least one of the preceding claims, characterized in that a cross-sectional area of the drainage bore (20) widens starting from the inlet opening (21) in the direction of the outlet opening (23). Internal combustion engine (1) according to at least one of the preceding claims, characterized in that a fluidic connection is provided between the oil collection channel (13) and a circulating cooling channel (25) arranged in the region of the ring section (10) or the piston head (9). Internal combustion engine (1) according to at least one of the preceding claims, characterized in that the oil collecting channel (13) is formed by an undercut of a groove (17) arranged in the piston skirt (6) and extending in the direction of the piston center axis (15). Internal combustion engine (1) after Claim 9 characterized in that a wall surface of the groove (17) adjacent to the oil scraper ring (12) is formed as an inclined deflecting surface (19). Internal combustion engine (1) according to at least one of Claims 1 to 8th , characterized in that the annular part (10) of the piston (4) by a circumferential annular recess (30) is so separated from the piston skirt (6) that the piston skirt (6) is thermally decoupled. Internal combustion engine (1) after Claim 11 , characterized in that the oil collection channel (13) in one of the ring part (10) facing free end face (31) of the piston skirt (6) is arranged. Internal combustion engine (1) according to Claims 11 or 12 , characterized in that the oil collection channel (13) adjacent and the piston center axis (15) facing surface portion (37) of the free end face (31) of the piston skirt (6) has an inclination in the direction of the oil collection channel (13). Internal combustion engine (1) according to at least one of the preceding Claims 11 to 13 Characterized in that the oil scraper ring (12) adjacent and the skirt (6) facing the piston bar of the ring part (10) as an at least in sections in the direction of the free end face (31) of the piston skirt (6) inclined guide surface (33) is formed, wherein an end section of the guide surface (33) facing the piston center axis (15) forms a drip edge (34) and a radial distance between the drip edge (34) and the piston center axis (15) is greater than or equal to a radial distance between an opening cross section of the oil collection channel (13 ) limiting inner edge (36) of the free end face (31) of the piston skirt (6) and the piston center axis (15). Internal combustion engine (1) according to at least one of Claims 11 to 14 , characterized in that one of the piston center axis (15) facing inner wall surface (38) of the oil collection channel (13) is designed such that an undercut in the oil collection channel (13) is formed.

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