GB2431218A - Piston with a cooling gallery - Google Patents
Piston with a cooling gallery Download PDFInfo
- Publication number
- GB2431218A GB2431218A GB0520638A GB0520638A GB2431218A GB 2431218 A GB2431218 A GB 2431218A GB 0520638 A GB0520638 A GB 0520638A GB 0520638 A GB0520638 A GB 0520638A GB 2431218 A GB2431218 A GB 2431218A
- Authority
- GB
- United Kingdom
- Prior art keywords
- piston
- oil
- gallery
- skirt
- cooling gallery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000001816 cooling Methods 0.000 title claims abstract description 23
- 238000002485 combustion reaction Methods 0.000 claims abstract description 15
- 230000037361 pathway Effects 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000005304 joining Methods 0.000 claims description 2
- 238000005461 lubrication Methods 0.000 description 11
- 241001125879 Gobio Species 0.000 description 8
- 230000006835 compression Effects 0.000 description 6
- 238000007906 compression Methods 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 4
- 238000005266 casting Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J9/00—Piston-rings, e.g. non-metallic piston-rings, seats therefor; Ring sealings of similar construction
- F16J9/12—Details
- F16J9/22—Rings for preventing wear of grooves or like seatings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/16—Pistons having cooling means
- F02F3/20—Pistons having cooling means the means being a fluid flowing through or along piston
- F02F3/22—Pistons having cooling means the means being a fluid flowing through or along piston the fluid being liquid
- F02F3/225—Pistons having cooling means the means being a fluid flowing through or along piston the fluid being liquid the liquid being directed into blind holes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J1/00—Pistons; Trunk pistons; Plungers
- F16J1/08—Constructional features providing for lubrication
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
- Lubrication Of Internal Combustion Engines (AREA)
Abstract
A piston for an internal combustion engine, comprising a head and a skirt, a cooling gallery in the piston head, and a hole opening into the cooling gallery from the underside of the piston to allow oil to be introduced as a jet into the gallery, characterised in that an exit pathway is provided to enable oil from the gallery to drain onto the radially outer surface of the skirt.
Description
Piston Design This invention relates to the design of pistons for use in
internal combustion engines, and more specifically to engines employing oil jets to cool the pistons.
Internal combustion engines, in particular compression ignition engines, experience very high in-cylinder temperatures. In the case of diesel engines, combustion often occurs within a dished section of the piston head, which means that the majority of heat lost from combustion to the surrounding area is transmitted through the body of the piston.
Apart from reducing the expected life of a piston, high piston temperature affects combustion efficiency and can lead to pre-ignition of the mixture. For these reasons, pistons for compression ignition engines are often cooled by a jet of oil sprayed from a nozzle mounted on the engine block below the cylinder bore. The fine jet is accurately sprayed at an aperture in the underneath of the piston which communicates with a gallery within the piston. The gallery is an annular chamber cast into the piston body, by inserting a salt fillet into the mould. Once solidified, entry and exit holes are drilled into the gallery from the underside of the piston body and the salt fillet is flushed out by injecting a high pressure solvent to leave the desired cooling gallery.
Studies have shown that splashing of the jet against the moving parts of the piston assembly such as the gudgeon pin, the connecting rod and the lower face of the piston itself, not only help to lubricate the gudgeon pin, but also to lubricate the cylinder bore. The extra lubrication of the bore has been shown to further improve combustion efficiency by reducing rubbing friction.
With a view to improving the lubrication of the cylinder bore still further, the present invention provides a piston for an internal combustion engine, comprising a head and a skirt, a cooling gallery in the piston head, and a hole opening into the cooling gallery from the underside of the piston to allow oil to be introduced as a jet into the gallery, characterised in that an exit pathway is provided to enable oil from the gallery to drain onto the radially outer surface of the skirt.
The piston may further comprise a feed pipe connected to the hole opening into the cooling gallery from the underside of the piston to enable oil pressure, when in use, to build up within the cooling gallery.
The piston may be further improved by providing a V- section channel in the piston skirt along which oil from the exit pathway can flow.
The V-section channel may advantageously be cast during manufacture of the piston but it may alternatively be machined after the piston has been cast.
It is preferred for a face of the V-section channel to be substantially perpendicular to a line joining the channel to the cooling gallery.
The present invention will now be described further by way of example with reference to the accompanying drawings in which: Figures 1 and 2 show perspective views of a piston according to the present invention, Figure 3 shows a cross section through a piston according to the present invention, and Figure 4 part of the section of Figure 3 drawn to an enlarged scale and highlighting the invention.
Figures 1 and 2 show similar, but rotationally staggered, views of a piston. The piston 10 is specifically intended for a compression ignition engine and has a deep bowl 20 within the piston head. In compression ignition engines this bowl serves as the combustion space and as a result the piston absorbs much of the heat from combustion of the charge.
Turning now to Figure 3, it is possible to see the internal construction of the piston. The piston is pivotably connected to the small end of a connecting rod (not shown) by a gudgeon pin 22. Because of the clearance between the piston and the cylinder bore, the piston tends to rock slightly relative to the cylinder block about the axis of the gudgeon pin as it reciprocates.
Clearance is required to allow for expansion of the piston due to the extremes of heat created in the combustion space. A ring assembly 24 including a top compression ring, is utilised to allow the piston to expand whilst still ensuring that the combustion chamber remains sealed.
The rocking effect described above can lead to the piston seizing in the bore, which will destroy the engine.
In order to counteract this effect, common piston design includes a piston skirt 12, which extends circumferentially downwards from the lowest piston ring (the oil control ring) between the gudgeon pin ends on both sides of the piston.
The length of the skirt 12 determines the maximum amount the piston can rock and hence the longevity of the engine, this is a trade off against the increase in piston weight which affects engine responsiveness.
As the piston 10 reciprocates in the cylinder bore, the skirt remains in contact with the cylinder lining. This leads to friction, which reduces engine efficiency and also increases the rate of wear. It has been suggested to apply a PTFE coating to the skirt 12 but this adds substantial cost and itself wears out in time.
Some lubrication is provided by way of splash of the crankshaft through oil in the oil sump. Also, in engines provided with oil jets for cooling the underneath of the piston, the oil used to cool the piston serves additionally to lubricate the gudgeon pin and potentially the surface of the cylinder bore swept by the piston skirt.
The present invention augments the lubrication of the cylinder bore in an engine having such oil jets. Oil jets are used to control piston temperature both for longevity and combustion efficiency. Pistons that are cooled by oil jets are often provided with a cooling gallery 18 in the form of a annular hollow chamber cast into the body of the piston during manufacture. A salt ring is positioned in the mould during the casting process and, after the piston has been cast, a hole is machined between the underside of the piston and the cooling gallery, allowing the salt is flushed out with water.
In conventional pistons equipped with a cooling gallery 18, at least one supply and one drainage hole are required to allow a continuous throughput of oil. Oil is supplied to the gallery 18 via a feed entry pipe 26, which opens to the underside of the piston 10. An oil spray nozzle attached to the engine block below each cylinder directs a jet of oil accurately into the feed pipe 26.
If the jet is consistently sprayed, it is possible to build up positive pressure within cooling gallery 18. The present invention differs from conventional pistons as described above in that, instead of or in addition to a hole to drain oil from the cooling gallery 18 back into the sump, it is provided with at least one radial skirt lubrication pathway 16 from the cooling gallery 18, which carries oil to the surface of the piston skirt 12 that contacts the cylinder bore.
In this way, oil pressure within the cooling gallery 18 forces oil onto the outside of the piston skirt 12 producing a sustainable film of oil between the skirt and the cylinder bore.
Figure 3 shows the ring assembly 24, which normally consists of an upper compression ring, a central scraper ring, and a lower oil control ring. The control ring is in place to prevent oil on the bore from entering and burning in the combustion chamber.
Conventionally, oil drains from the standard exit pathway to the underside of the piston, via the gudgeon pin/piston bearing which relies on this and splash from the sump for lubrication. It is preferable to retain the standard exit pathways in order that the gudgeon pin should remain lubricated, and also because the volume of oil delivered to the skirt 12 by means of the skirt lubrication pathway 16 must be carefully determined to avoid over lubrication, which can lead to increased friction.
In order to deliver oil effectively to the piston skirt 12, the piston is formed with a channel 14 within the top most area of the skirt 14 adjacent and parallel to the bottom of the ring assembly 24. The channel 14 communicates with the downstream end of skirt lubrication pathway 16.
Channel 14 has a V-shaped cross section that provides a larger opening from which the oil is delivered to the walls of the cylinder bore and the skirt 12 of the piston as it reciprocates. While the channel 14 may be easily produced during the casting procedure, it may alternatively be machined after the piston has been cast.
As shown in Figure 4, the channel 14 also allows easy drilling of skirt lubrication pathway 16. By making the V- section channel 14 such that one of its two faces is perpendicular to the direction of the skirt lubrication pathway 16 (angle a is substantially equal to 90 )drilling of the piston to produce the pathway 16 is simplified.
It should be mentioned that it is known to provide holes in a piston wall which opens into the annular recess that receives the oil control ring. As the piston moves down the cylinder bore, oil which has been splashed onto the cylinder bore is scraped off by the oil control ring and the purpose of the holes in the piston is to allow this oil to drain back into the sump via the exposed underside of the piston. The purpose of the holes in prior art pistons is therefore exactly the opposite of the pathway 16 provided by the present invention between the piston skirt and the cooling oil gallery 18 in as much as the direction of oil flow is reversed.
Claims (7)
- Claims 1. A piston for an internal combustion engine, comprising a head, askirt, a cooling gallery in the piston head, and a hole opening into the cooling gallery from the underside of the piston to allow oil to be introduced as a jet into the gallery, characterised in that an exit pathway is provided to enable oil from the gallery to drain onto the radially outer surface of the skirt.
- 2. A piston as claimed in claim 1, further comprising a feed pipe connected to the hole opening into the cooling gallery from the underside of the piston to enable oil pressure, when in use, to build up within the cooling gallery.
- 3. A piston as claimed in claim 1 or 2, further comprising a V-section channel in the piston skirt along which oil from the exit pathway can flow.
- 4. A piston as claimed in claim 3, wherein the channel is cast during manufacture of the piston.
- 5. A piston as claimed in claim 3, wherein the channel is machined after manufacture of the piston.
- 6. A piston as claimed in any claims 3 to 5, wherein a face of the vsection channel is substantially perpendicular to a line joining the channel to the cooling gallery.
- 7. A piston substantially as herein described with reference to and as illustrated in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0520638A GB2431218B (en) | 2005-10-11 | 2005-10-11 | Piston with oil drain onto outer surface of skirt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0520638A GB2431218B (en) | 2005-10-11 | 2005-10-11 | Piston with oil drain onto outer surface of skirt |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0520638D0 GB0520638D0 (en) | 2005-11-16 |
| GB2431218A true GB2431218A (en) | 2007-04-18 |
| GB2431218B GB2431218B (en) | 2010-06-09 |
Family
ID=35430174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0520638A Expired - Fee Related GB2431218B (en) | 2005-10-11 | 2005-10-11 | Piston with oil drain onto outer surface of skirt |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2431218B (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102011012686A1 (en) * | 2011-03-01 | 2012-09-06 | Mahle International Gmbh | Piston for an internal combustion engine |
| DE102011012685A1 (en) * | 2011-03-01 | 2012-09-06 | Mahle International Gmbh | Piston for an internal combustion engine |
| DE102011119525A1 (en) * | 2011-11-26 | 2013-05-29 | Mahle International Gmbh | Piston for an internal combustion engine |
| CN104024586A (en) * | 2011-11-09 | 2014-09-03 | 瓦锡兰芬兰有限公司 | Lubrication arrangement |
| US8973484B2 (en) | 2011-07-01 | 2015-03-10 | Mahle Industries Inc. | Piston with cooling gallery |
| US20170306832A1 (en) * | 2015-01-14 | 2017-10-26 | Achates Power, Inc. | Piston cooling for opposed-piston engines |
| US9856820B2 (en) | 2010-10-05 | 2018-01-02 | Mahle International Gmbh | Piston assembly |
| EP3502452A1 (en) * | 2017-12-21 | 2019-06-26 | MAN Truck & Bus AG | Piston for a reciprocating piston combustion engine |
| DE102018208898A1 (en) * | 2018-06-06 | 2019-12-12 | Volkswagen Aktiengesellschaft | Reciprocating piston for a reciprocating internal combustion engine and use of a reciprocating piston in a reciprocating internal combustion engine |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4587932A (en) * | 1984-02-02 | 1986-05-13 | Kolbenschmidt Aktiengesellschaft | Liquid-cooled composite piston for internal combustion engines |
| DE3707462A1 (en) * | 1987-03-07 | 1988-09-15 | Man B & W Diesel Gmbh | Oil-cooled, multi-part trunk piston for internal combustion engines |
-
2005
- 2005-10-11 GB GB0520638A patent/GB2431218B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4587932A (en) * | 1984-02-02 | 1986-05-13 | Kolbenschmidt Aktiengesellschaft | Liquid-cooled composite piston for internal combustion engines |
| DE3707462A1 (en) * | 1987-03-07 | 1988-09-15 | Man B & W Diesel Gmbh | Oil-cooled, multi-part trunk piston for internal combustion engines |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9856820B2 (en) | 2010-10-05 | 2018-01-02 | Mahle International Gmbh | Piston assembly |
| DE102011012686A1 (en) * | 2011-03-01 | 2012-09-06 | Mahle International Gmbh | Piston for an internal combustion engine |
| DE102011012685A1 (en) * | 2011-03-01 | 2012-09-06 | Mahle International Gmbh | Piston for an internal combustion engine |
| US20120285404A1 (en) * | 2011-03-01 | 2012-11-15 | Mahle International Gmbh | Piston for an internal combustion engine |
| CN103403407A (en) * | 2011-03-01 | 2013-11-20 | 马勒国际公司 | Piston for an internal combustion engine |
| CN103403406A (en) * | 2011-03-01 | 2013-11-20 | 马勒国际公司 | Piston for an internal combustion engine |
| US8689743B2 (en) | 2011-03-01 | 2014-04-08 | Mahle International Gmbh | Piston for an internal combustion engine |
| CN103403407B (en) * | 2011-03-01 | 2016-11-16 | 马勒国际公司 | Internal combustion engine |
| US8973484B2 (en) | 2011-07-01 | 2015-03-10 | Mahle Industries Inc. | Piston with cooling gallery |
| CN104024586B (en) * | 2011-11-09 | 2016-08-17 | 瓦锡兰芬兰有限公司 | Lubricating arrangement |
| CN104024586A (en) * | 2011-11-09 | 2014-09-03 | 瓦锡兰芬兰有限公司 | Lubrication arrangement |
| US9068529B2 (en) | 2011-11-26 | 2015-06-30 | Mahle International Gmbh | Piston for an internal combustion engine |
| DE102011119525A1 (en) * | 2011-11-26 | 2013-05-29 | Mahle International Gmbh | Piston for an internal combustion engine |
| US20170306832A1 (en) * | 2015-01-14 | 2017-10-26 | Achates Power, Inc. | Piston cooling for opposed-piston engines |
| US10001050B2 (en) * | 2015-01-14 | 2018-06-19 | Achates Power, Inc. | Piston cooling for opposed-piston engines |
| US10871099B2 (en) | 2015-01-14 | 2020-12-22 | Achates Power, Inc. | Piston cooling for opposed-piston engine |
| EP3502452A1 (en) * | 2017-12-21 | 2019-06-26 | MAN Truck & Bus AG | Piston for a reciprocating piston combustion engine |
| DE102018208898A1 (en) * | 2018-06-06 | 2019-12-12 | Volkswagen Aktiengesellschaft | Reciprocating piston for a reciprocating internal combustion engine and use of a reciprocating piston in a reciprocating internal combustion engine |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0520638D0 (en) | 2005-11-16 |
| GB2431218B (en) | 2010-06-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20201011 |