ES2298187T3 - PISTON, ESPECIALLY FOR AN INTERNAL COMBUSTION ENGINE. - Google Patents

Abstract

Piston (1) comprises a piston head (2), a piston shaft (3) having a pair of piston pin hubs (4, 5) and set back in the region of the piston pin hubs so that the piston head protrudes in a radial direction over the piston shaft in the region of the piston pin hubs, an inner piston chamber defined by the piston shaft and the piston head and having an oil-guiding wall forming an oil jet impact zone (10), and at least one through channel (16, 17, 22) leading outward from the inner piston chamber so that oil flowing through the through channel flows against the piston head in its region protruding over the piston shaft. Preferred Features: The oil-guiding wall changes into the inner wall of the through channel.

Description

Piston, especially for an engine internal combustion.

The invention concerns a piston, especially for an internal combustion engine, with a head of piston and with a piston rod comprising pin hubs of piston and that is set in a recessed way in the region of each of these piston pin hubs such that a segment of the piston head segment protrudes from the area recessed piston rod.

A piston of this class is known by the document DE 197 47 746 C1. An opening is formed in this piston  of oil injection in the region of the piston head that protrudes from the piston rod. The introduction of oil in this oil injection opening is made by means of a oil jet projected in the direction of the injection opening of oil, which extends in an intermediate space between the piston rod and cylinder wall. The oil injected into the oil injection opening runs through an annular channel that extends in the region of the grooves of the piston rings, and arrives then to an exit opening. The manufacture of this piston is manifests as relatively complicated according to criteria manufacturing technicians

The invention is based on the problem of creating a cheap piston to manufacture, especially for a motor internal combustion, in which a heat evacuation is guaranteed enough along with a favorable temperature profile.

This problem is solved according to the invention by means of a piston comprising a piston head, a rod of piston comprising a pair of piston pin hubs and which presents a construction set back in the region of the cubes of the piston pin, so that the piston head protrudes in radial direction from the piston retracted rod in the region of the piston pin hubs, an interior space of the piston limited by the piston rod and the piston head and equipped with an oil conduction wall there provided that encloses an impact zone of the oil jet, and at least one closed passage channel that runs in a direction that starts from the inside the piston so that the oil circulates through the passage channel and exits through at least one exit opening, with that, after leaving the closed passage channel, the oil bathes the piston head in its protruding area of the stem of the piston.

It is thus technically possible advantageous to create a relatively light piston that can undergo at high mechanical and thermal load and in which a Reliable cooling in the edge region of the head of the piston, especially in the region of the part flown beyond of the piston rod, referred to in what follows as a ring piston. In view of the oil led to the balconies of the piston rings, immediately after impact on the jet impact zone, sweep an interior wall area of the piston adjacent to the piston rings and is also driven also in the passageways near the piston rings, a homogenized temperature profile results in the region of the piston head

In view of the improved temperature profile of the piston, higher compression ratios can be admitted. Also, the oil line according to the invention is manifested also as especially advantageous in regards to a increased service life of an internal combustion engine.

According to an embodiment especially preferred of the invention, the oil conduction wall is configured in such a way that it transitions to the wall inside the passage channel in the region of a flow path of oil. In this way, apart from an effective introduction of the jet of diverted oil in the passage channel, you also get a Improved heat transmission to oil. The entrance region of passage channel is preferably configured in a widened manner to funnel way and is arranged in a corner region inside.

A resistance is advantageously achieved especially high mechanical piston driving the passage channel along the piston pin hubs. It avoids this way a weakening of the transition region between the region of the piston rod hubs and the piston head.

The passage channel extends for it preferably towards the edge region of the piston bulging laterally and passing sickle way along the cubes of the piston pin

A transmission of preferably is achieved especially effective heat to the oil making the passageway run under the piston rod through the head of the piston. It is then possible to effectively avoid a thermal load of the piston head, especially in the region of its wall next to the combustion chamber.

The oil conduction surface is formed advantageously by means of the inner wall of the stem of the piston in cooperation with the bottom side of the piston head and preferably comprises a spreading area that extends from the impact zone of the jet into the passage channel. It is thus possible to drive the projected oil almost completely into the passage channel.

Preferably, at least one passage channel is provided for each of the sections of the piston head projecting radially from the piston rod. It is thus possible to uniformly cool the balconies of the piston rings provided on both sides and formed by the piston head. However, each hub of the piston pin has two advantageously associated passageways which, swelling laterally towards the edge of the piston, run around the piston pin hub through the piston rod and / or the head of the piston.
piston.

The jet impact zone is located preferably on the side of the piston subjected to greater load thermal Under a uniform thermal load on the upper side of the piston, the area of impact of the jet is preferably in the middle of the inner space of the piston rod of that wall of said rod that rests on a cylinder wall during a work career.

According to a special aspect of this invention, a cooling action is achieved especially high causing the inner region of the piston rod to be formed a second zone of impact of the jet. Preferably, a total of four pass channels are planned here that are extend around the piston pin hubs towards a central region of the balconies of the piston rings.

The cross section of the passage channels preferably amounts to at least 15% of the surface of the cross section of the piston pin drill. Is achieved an especially effective heat transmission when the section Transverse of the passage channels is sized in such a way that this corresponds at least to the ratio of the oil stream projected by an oil injection nozzle and a average oil jet impact speed.

The piston is preferably manufactured as a casting piston You can then configure the step channel in a favorable way for the manufacturing technique. The surface of the passage channel can be substantially cast Gray. It is also possible to manufacture the piston through a process forging The passage channel is then preferably formed in the frame of a subsequent mechanization with chip removal.

The oil jet impact zone is preferably configured such that it causes a division of the oil jet into at least two partial streams. Preferably, each of the two currents is conducted partial towards one of the two parts blown from the head of the piston.

The blown part of the piston head presents according to an especially preferred embodiment of the invention, seen in axial direction, a shape configuration substantially circular segment, passing the passage channel in a direction such that this one requests with oil the flown part of the piston head from a region adjacent to the tips of the segment and in the direction of the segment axis.

The oil conduction wall, the channel step and deviation zone in the region of the flown part of the piston head preferably form a conduction path of oil with a large contact area with the oil. He contact with the oil is preferably intensified by means of a multiple deviation of the oil, especially by means of deviation zones with increasing curvature.

Other advantageous details of the invention are they follow from the following description in conjunction with the drawing. They show:

Figure 1, a perspective view of the inner region of a piston according to a first embodiment of the invention with an insinuated oil conduction route;

Figure 2, a perspective view of a piston according to a second embodiment, also taken from below,

Figure 3, a perspective view from under a piston according to a third embodiment of the invention with an oil outlet region configured in the form of bucket;

Figure 4, a detailed perspective view of the oil jet impact zone according to a fourth way of embodiment of the invention with an oil conduction wall pumped like a groove, protruding in an arc towards the edge of the piston and leads to the passageways;

Figure 5, a perspective view from outside the region of the piston pin hubs formed in the piston rod according to a fifth embodiment of the invention;

Figure 6, a perspective view of the balcony of a piston segment of a sixth embodiment of a piston according to the invention;

Figure 7, an axial sectional view of a seventh embodiment of a piston according to the invention with implied oil jet directed obliquely towards the region inside of the piston; Y

Figure 8, a radial sectional view of the piston according to figure 7 at the height of the pin axis of the piston.

The piston 1 represented in certain sections from below in figure 1 comprises a piston head 2 visible here only with respect to its lower side and a piston rod 3 set up in one piece with her.

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The piston rod 3 comprises two hubs 4, 5 of piston pin with a few holes 6 of piston pin aligned. The piston rod 3 has a construction recessed in the region of hubs 4, 5 of the piston pin of such that the piston head 2 protrudes from the rod 2 of the Cantilever piston out in radial direction. The region of the head 2 of the piston protruding from the rod 3 of the piston has, seen from an axial direction, a configuration substantially in the form of a circular segment. It represents here sketch way a corresponding circular segment widely symmetrical in this view with respect to the X axis of the bolt of the piston.

The region of the piston head 2 which projecting radially in cantilever of piston rod 3 forms a 7 piston ring balcony. This balcony 7 comprises in its region bottom turn towards the X axis of the piston pin an area of 8 cooling requested by cooling oil.

The cooling oil feed to the cooling zone 8 is carried out by means of an oil jet 9 directed towards an inner region of the piston rod 3. This oil jet 9 is oriented in such a way that it impacts on a jet impact zone 10 formed in the interior region of the piston rod 3.

The jet impact zone 10 is located here near the edge region of piston 1 and is formed by an inner surface section of the piston rod 3 and by the lower inner surface of the piston head 2. In the region of the jet impact zone 10 a deviation and a division of the oil jet in at least two partial currents 11, 12, 13. The two partial currents 11, 12 they are led to input openings 14, 15 of passage channels 16, 17 by means of the inner wall of the piston 1 acting as oil conduction surface. The contact between the circulating oil and the piston wall making the path of the oil runs curved so that the oil is propelled against the oil conduction wall by forces Radials that then go into action.

The channels 16, 17 extend in shape of sickle along the root region of cubes 4, 5 of the piston pin to a heat exchange zone K (see sketch of the circular segment) of the balcony 7 of the piston ring. The solicitation of the lower region of the balcony 7 of the piston ring it is carried out in a directed way from the region of the tips S1, S2 of the circular segment towards the X axis of the piston pin.

In the region of the K exchange zone of heat are provided several outlet openings 18, 19, 20, 21. Through souls formed between the outlet openings 18, 19, 20, 21 the area that is available for heat exchange The outlet openings 18, 19 are used for evacuation of oil from the partial oil stream 12. The outlet openings 20, 21 serve for the evacuation of oil fed by a second jet of oil (not shown) to through another channel of passage 22.

The passage channel 17 extends in such a way running under the piston rod 3 through the head 2 from the last batch. The evolution of the curvature has been chosen in such so that the oil sweeps primarily the hottest areas of the passageway wall.

In the region of the balcony 5 of the piston ring, bypasses the oil fed through the passageways 17, 22 such that this oil is projected in the direction substantially parallel to the axis of the piston stroke or to the Recessed wall of piston rod 3. It is possible to adjust the geometry of the balcony area 7 of the piston ring requested by oil - and therefore the projection characteristic - of such so that a defined lubrication of the wall of the cylinder.

Figure 2 shows a view from below a second embodiment of a piston 1. In this embodiment the piston rod 3 is also of construction set back in the region of hubs 4, 5 of the bolt of the piston, thereby forming balconies 7 of the rings of the piston.

In the inner space of the limited piston jointly by the piston rod 3 and the head 2 of this Finally, two jet impact zones 12, 14 are formed in the transition region between piston rod 3 and head 2 of the latter. Through these areas 12, 24 of impact of the jet is divide the oil jets 9, 9 'directed in pairs towards the inner region of the piston and these are conducted as currents corresponding partial towards the channels of passage 17, 16, 22, 22 '. In this embodiment, the channels 17, 16, 22, 22 'also run sickle-shaped and bulging laterally around the respective hub region of the stem 3 of the piston.

On the lower side of the balcony 7 of hoop circular segment-shaped piston is the K zone of heat exchange This heat exchange zone K comprises three outlet openings 18, 19 'and 21. The outlet openings 18, 19 'and 21 have a substantially shaped cross section circulate and communicate with both adjacent passageways 17, 22, so that, especially through the exit opening central 19 ', oil fed can flow through the channel step 17 or the passage channel 22. The layout of the passage channels 17, 22 has been hinted by dashed lines. Due to the route chosen here from the channels of step 17, 22, which has arc shape and penetrates the head 2 of the piston, it has to, apart from a cooling of the balconies 7 of the hoops of the piston, heat evacuation of the zones is also achieved adjacent to the piston rings.

The entrance openings 14, 15 are located in a corner region that is defined by the inner wall of the piston rod 3, the hub regions 4, 5 of the piston project inward and the underside of head 2 of the piston. In this way a funnel action is achieved. This action funnel is further favored, in assembled state, by the region Top of a connecting rod.

The piston 1 also shown from below in certain sections in figure 3 correspond substantially to the piston according to figure 2 in regards to the configuration of the region inner limited by piston rod 3 and head 2 of this latest. In line with this, the explanations are applicable referring to figure 2, except for the differences that set out below.

The piston according to figure 3 is provided in the balcony region 7 of the piston ring an oil path 25 deepened by way of trough and open down. This way of oil 25 is requested on both sides with oil from the region corner of the heat exchange zone K and extends around the hubs 4, 5 of the piston pin from the region inside the piston and through the passageways 17, 22.

The geometry of the oil path 25, especially from an outer peripheral edge 26 of depression to trough way, it has been established in such a way that the oil fed be projected down in substantially direction parallel to the direction of oscillation of the piston. It's possible to do so big this oil route in regards to its volume that an oil projection takes place - at least for the most part - only in a lower neutral position of the piston.

In the embodiment shown here, The depth of the oil path 25 is approximately 8 mm. The width of the oil path, measured in the radial direction of the piston, is preferably within the range of 4 to 6 mm. These data refer to a piston with a diameter of approximately 80 mm The length of the oil line 25, measured in the peripheral direction, it corresponds substantially at least to the width b of the piston pin hub 4.

Figure 4 shows a view of detail of an inner region of the piston with a specially  10 jet impact set. The impact zone 10 of jet is in a transition region between the wall inside of piston rod 3 and lower side of head 2 of said piston. The wall sections that come into contact with the oil form an oil conduction surface G which is of configuration pumped as a channel and transition to the inner surface of the passageways 17, 16. The surface G oil conduction, apart from driving the oil, performs also a transmission of heat to the oil and thus makes possible a cooling of the adjacent region of the piston edge.

The grooving action of surface G of Oil conduction is favored by an edging area 27. Through the oil conduction surface G here sample, the jet that impacts the impact zone 10 of jet is driven along the inner edges of the cubes 4, 5 of the piston pin to a corner region as a funnel.

Figure 5 shows another form of realization of the heat exchange zone K of the balcony 7 of a piston ring In this embodiment an attack is made exclusively unilateral of the heat exchange zone K by part of an oil stream - hinted here by means of a arrow symbol - projected in the outward direction of the channel step 17 '. In the heat exchange zone K it is formed also in this exemplary embodiment an oil path 25 that It has a weak lateral bulge towards the edge of the piston. This oil route 25 ends in a deflection zone 30 in which the incoming oil stream is diverted to the crankshaft of the Internal combustion engine. In this embodiment, the passage channel 17 is in a half of the remaining piston away from a piston pressure side 31. You get a enhanced lubrication film formation during a run of expansion

Figure 6 shows another form of realization of a piston with a bottom side of a hoop balcony 7 of piston attacked on one side by the current of a passage channel 17 '. In this embodiment the oil jet 32 is deflected along the bore 6 of the piston pin by means of a deflection trough 33 formed on the piston rod 3. The deviation trough 33 is configured in such a way that the oil jet 32 deflected is projected onto the bearings of the crankshaft in direction substantially parallel to the wall of the cylinder. The oil is fed to the passage channel 17 ' also in this embodiment by means of a wall of oil conduction provided in the inner region of the stem 3 of the piston, as is the case in the embodiments previously described.

Another example is shown in Figures 7 and 8 of realization of a piston 7 with a piston rod 3 which is of laterally narrowed construction in the region of cubes 4, 5 of the piston pin. Head 2 of piston 1 protrudes here from the piston rod 3 projecting cantilever in radial direction. In the region of the piston ring balconies 7 thus obtained are formed oil paths 25 that bulge outward and that They are open down. The surface of the piston head equipped here with a strong profile and turn towards the chamber of combustion has been represented in this case turned by 90º.

These 25 oil routes planned in the region of each piston ring balcony 7 are fed through channels of step 16, 17 with oil that, making an impact in an area 10 of jet impact near the edge of the piston, is injected by means of a nozzle 34 - in the region of a bearing arrangement of the crankshaft - in the inner region of the piston rod 3.

Projected oil feed to channels 16, 17 are also carried out here by means of a oil conduit wall extending to said channels step 16, 17. The oil path in the inner region of the stem 3 of the piston runs in the region near the edge of the piston, of so that effective cooling of the entire region of the edge of the piston head. The oil path extends swelling laterally in the radial direction and sickle-shaped around the hubs 4, 5 of the piston pin. In the background, in this embodiment the entire inner surface of the head of the piston that looks down forms a driving surface of oil that ends in the passageways. Due to the current of oil close to the piston rings and - regardless of stretches located within the passageways - open you get a large heat exchange surface in an advantageous manner for the manufacturing technique.

Due to its improved temperature profile and its low own weight, the piston according to the invention is suitable especially advantageous for GDI engines.

The invention is not limited to the examples of embodiment described above. For example, it is also possible  that the oil sprayed on the oil conduction surface be projected from several oil injection nozzles that, referred to the axis of their jet, they are oriented obliquely with with respect to the axis of the cylinder. Depending on the position of the piston the distance of the point of impact of the jet can be varied with relation to the passage channel. The oil injection nozzle can be also arranged in the connecting rod itself.

Claims (12)

1. Piston with a piston head (2), a piston rod (3) comprising a pair of bolt hubs (4, 5) of piston and that is of construction set back in the region of said hubs (4, 5) of the piston pin, so that, in the region of these hubs (4, 5) of the piston pin, the head (2) of the pin overhangs radially with respect to the rod setback (3) of the piston, an interior space of the piston limited by the piston rod (3) and the head (2) of this last and equipped with an oil conduction wall provided in the same that forms an oil jet impact zone (10), and at minus a closed passage channel (16, 17, 22, 22 ') that runs from the inner space of the piston in a direction such that the oil it crosses the passage channel (16, 17, 22, 22 ') and leaves through at minus an exit opening (18, 19, 20, 21), so that this oil, after leaving the closed passage channel (16, 17, 22, 22 '), flows to the head (2) of the piston in its region that overhangs the piston rod (3). 2. Piston according to claim 1, characterized in that the oil conduction wall transitions into the inner wall of the passage channel (16, 17, 22, 22 '). 3. Piston according to claim 1 or 2, characterized in that the passage channel (16, 17, 22, 22 ') extends in the head (2) of the piston or in the rod (3) of the latter along the hubs (4, 5) of the piston pin and deviates laterally towards the edge of the piston. 4. Piston according to at least one of claims 1 to 3, characterized in that in a region offset with respect to a plane defined by the central axis of the piston and the axis of the bolt of this piston the passage channel (16, 17, 22 , 22 ') runs below the piston rod (3) through the head (2) of the latter. 5. Piston according to at least one of claims 1 to 4, characterized in that the passage channel (16, 17, 22, 22 ') extends like a sickle along the hubs (4, 5) of the bolt of the piston. 6. Piston according to at least one of claims 1 to 5, characterized in that the oil conducting surface is formed by the inner wall of the piston rod (3) in cooperation with the lower side of the piston head (2) and it comprises a groove zone (G) that extends from the impact zone (10) of the oil jet into the passage channel (16, 17, 22, 22 '). 7. Piston according to at least one of claims 1 to 6, characterized in that the impact zone (10) of the oil jet is configured such that it produces a division of the oil jet (9) into at least two partial streams (11, 12, 13). 8. Piston according to claim 7, characterized in that each of the two partial currents (11, 12) is led to one of the cantilever protruding regions of the piston rod. 9. Piston according to at least one of claims 1 to 8, characterized in that at least one passage channel (16, 17, 22, 22 ') is provided for each of the regions projecting overhang of the piston rod. 10. Piston according to at least one of claims 1 to 9, characterized in that a second oil jet impact zone is formed in the inner zone of the piston rod (3). 11. Piston according to at least one of claims 1 to 10, characterized in that a total of four passage channels (16, 17, 22, 22 ') are provided that extend around the hubs (4, 5) of the bolt of the piston to the center of gravity of the surface of the lower side of the respective overhang region of the piston rod. 12. Piston according to at least one of claims 1 to 11, characterized in that the cross-section of the passageways (16, 17, 22, 22 ') amounts to at least 15% of the surface of the cross-section of the bore (6) of the piston pin.