EP1004765A1 - Dispositif de culasse de moteur à explosion pour diminuer les contraintes thermiques - Google Patents

Dispositif de culasse de moteur à explosion pour diminuer les contraintes thermiques Download PDF

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Publication number
EP1004765A1
EP1004765A1 EP99123425A EP99123425A EP1004765A1 EP 1004765 A1 EP1004765 A1 EP 1004765A1 EP 99123425 A EP99123425 A EP 99123425A EP 99123425 A EP99123425 A EP 99123425A EP 1004765 A1 EP1004765 A1 EP 1004765A1
Authority
EP
European Patent Office
Prior art keywords
cylinder head
slit
cylinder
head according
ceiling
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.)
Withdrawn
Application number
EP99123425A
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German (de)
English (en)
Inventor
Akira c/o Toyota Jidosha K. K. Fujii
Kazuaki c/o Toyota Jidosha K. K. Sugimura
Hiroyuki c/o Toyota Jidosha K. K. Isawa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Publication of EP1004765A1 publication Critical patent/EP1004765A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
    • F02F1/4214—Shape or arrangement of intake or exhaust channels in cylinder heads specially adapted for four or more valves per cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
    • F02B2275/18—DOHC [Double overhead camshaft]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • 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
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F2001/244—Arrangement of valve stems in cylinder heads
    • F02F2001/245—Arrangement of valve stems in cylinder heads the valve stems being orientated at an angle with the cylinder axis
    • 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
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F2001/248—Methods for avoiding thermal stress-induced cracks in the zone between valve seat openings

Definitions

  • the present invention relates to a cylinder head structure for mitigating thermal stress in internal combustion engines.
  • a great amount of heat is produced in the combustion chambers of internal combustion engines such as diesel engines and gasoline engines.
  • locations on the cylinder center axes in a cylinder head are surrounded by the corresponding intake ports and exhaust ports, and they tend to be greatly heated since heat tends to concentrate at these locations, which are not readily cooled.
  • Japanese Unexamined Patent Publication No. 55-160143 and Japanese Unexamined Utility Model Publication No. 58-82453 describe an internal combustion engine having slits formed on the lower surface of a cylinder head between adjacent combustion chambers.
  • the slits absorb thermal strain and prevent cracks of the cylinder head and seal degradation.
  • the slits extend in a direction perpendicular to the longitudinal direction of the cylinder head between adjacent combustion chambers.
  • the slits are connected to head bolt holes and water jackets. Bolts for fixing the cylinder head to the cylinder block are received in the head bolt holes.
  • the strength of the cylinder head is reduced when the slits are connected to the head bolt holes or the water jackets. Therefore, the cylinder head may be deformed by various stresses, which reduces the effectiveness of the gasket between the cylinder head and the cylinder block. When the slits are connected to the water jackets, leakage of cooling water through the slits may occur.
  • An objective of the present invention is to provide a cylinder head structure for internal combustion engines that sufficiently mitigates thermal stress and maintains the strength of the cylinder head.
  • the present invention provides a cylinder head of an internal combustion engine.
  • the cylinder head is connected to a cylinder block that has a cylinder bore.
  • a contact surface faces the cylinder block.
  • the contact surface has a ceiling surface that closes an opening of the cylinder bore.
  • the ceiling surface and the cylinder bore define a combustion chamber.
  • a slit is formed on the contact surface adjacent the ceiling surface to mitigate thermal stress in the cylinder head.
  • the slit has a maximum depth part located near a center of the ceiling surface. The depth of the slit decreases as the distance from the maximum depth part increases. The slit is separated from other spaces in the cylinder head.
  • a cylinder head 2 of a diesel engine according to a first embodiment of the present invention will now be described with reference to Figs. 1-4.
  • the cylinder head 2 shown in Figs. 1-3 is made of aluminum alloy. As shown in Fig. 3, when the cylinder head 2 is attached to a cylinder block 11, which is made of cast iron, the bottom surface 2a of the cylinder head 2, or a contact surface, closes upper openings of cylinder bores 13, which are formed in the cylinder block 11.
  • the cylinder bores 13 and the bottom surface 2a define combustion chambers 15.
  • the areas encircled by broken lines in Fig. 1 on the bottom surface 2a of the cylinder head 2 function as flat ceiling surfaces 6 for the combustion chambers 15.
  • a pair of intake ports 8, a pair of exhaust ports 10, a nozzle hole 12, and a glow plug hole 14 are formed in each ceiling surface 6 of the cylinder.
  • annular step 8c is formed in the vicinity of the opening of each intake port 8 in the corresponding ceiling surface 6.
  • a ring-shaped valve seat 8a is attached to each step 8c.
  • An annular step 10c is formed in the vicinity of the opening of each exhaust port 10 in the corresponding ceiling surface 6.
  • a ring-shaped valve seat 10a is attached to each step 10c.
  • a tubular intake valve guide 8b is attached to the cylinder head 2 and is coaxial with each intake valve seat 8a.
  • a tubular exhaust valve guide 10b is attached to the cylinder head 2 and is coaxial with each exhaust valve seat 10a.
  • a poppet valve (not shown) is supported in each valve guide 8b, 10b to move axially. Each poppet valve separates from and contacts the corresponding valve seat 8a, 10a, which opens and closes the corresponding port 8, 10.
  • each slit 16 is formed on the bottom surface 2a of the cylinder head 2, between the adjacent ceiling surfaces 6.
  • each slit 16 extends in a direction perpendicular to the direction (shown by the arrow D of Fig. 1) in which the combustion chambers 15 are arranged.
  • the slit 16 has a pair of side walls 16c, which face each other.
  • each slit also includes a bottom wall 16b, which is arcuate. Accordingly, the center part of each slit 16 is its deepest part 16a, which corresponds to the center of each combustion chamber 15. The further from the deepest part 16a, the shallower each slit 16 becomes.
  • the cylinder head 2 includes head bolt holes 18, 20, in which bolts (not shown) are received to join the cylinder head 2 to the cylinder block 11.
  • the slits 16 are not connected to the head bolt holes 18, 20.
  • each slit 16 is independently formed and is not connected to other spaces in the cylinder head 2, such as water jackets 22, 24.
  • the head bolt holes 18, 20 are located at both ends of each slit 16. The depth of each slit 16 gradually decreases from the deepest part 16a towards the head bolt holes 18, 20
  • the depth H1 of the deepest part 16a of each slit 16 is substantially the same as the height H2 of the uppermost extent of the valve seats 8a, 10a (here, the top of the highest valve seat 8a of each intake port 8).
  • the depth H1 and the height H2 are both measured from the bottom surface 2a of the cylinder head 2.
  • the deepest part 16a is located close to and approximately in alignment with the uppermost position of the valve seat 8a of each intake port 8 in the longitudinal direction of the cylinder head 2.
  • the slits 16 are formed by cutting the bottom surface 2a of the cylinder head 2 with a disc-shaped cutter (not shown) .
  • the cross section of the edge of the disc-shaped cutter is U-shaped. Therefore, the cross section of the bottom wall 16b of each slit 16 is generally U-shaped as shown in Fig. 4. Accordingly, the bottom wall 16b of each slit 16 does not have any angular surfaces.
  • the width (in the direction of arrow D of Fig. 1) of each slit 16 is, for example, about 1mm.
  • a gasket 17 is located between the bottom surface 2a of the cylinder head 2 and the cylinder block 11.
  • the gasket 17 includes holes corresponding to the ceiling surfaces 6, holes corresponding to head bolt holes 18, 20, and holes corresponding to the openings of the water jackets 22, 24 in the bottom surface 2a of the cylinder head 2.
  • the gasket 17 closes the openings of the slits 16.
  • the present embodiment has the following advantages.
  • the central locations 26 are heated to an especially high temperature and are likely to be thermally stressed.
  • the deepest parts 16a of the slits 16 are formed at the longitudinal centers of the slits 16.
  • the deepest parts 16a of the slits 16 are the closest parts of the slits to the center locations 26 of the cylinder head 2, which are subject to the greatest thermal stress. Therefore, the relatively great thermal stress applied to the center locations 26 of the cylinder head 2 is effectively mitigated by the deepest parts 16a.
  • Each slit 16 becomes shallower from the deepest part 16a towards its ends. That is, only the part of each slit 16 that is close to the center locations 26 is formed to be relatively deep, and the rest of each slit 16 is relatively shallow. In this way, the slits are no deeper than is required. Therefore, the slits do not reduce the strength of the cylinder head 2. This prevents excessive deformation of the cylinder head 2 and improves sealing between the cylinder head 2 and the cylinder block 11.
  • each slit 16 changes continuously, not stepwise.
  • the bottom wall 16b of each slit 16 is arcuate.
  • the cross sectional shape of the bottom wall 16b is generally U-shaped. Accordingly, the wall that defines each slit 16 has no angles. Stress tends to concentrate at angular junctions, thus stress does not concentrate in the inner wall of the slits 16. This improves the durability of the cylinder head 2. Also, the slits 16 can be easily formed using a disk-shaped cutter, which improves productivity.
  • the slits 16 are independently formed and are not connected to other spaces such as head bolt holes 18, 20 or water jackets 22, 24. This sufficiently maintains the strength of the cylinder head 2 and prevents degradation of the seal between the cylinder head 2 and the cylinder block 11 and prevents leakage of water or oil via the slits 16.
  • the steps 8c, 10c for supporting the valve seats 8a, 10a are formed at the openings of the intake ports 8 and the exhaust ports 10. Since the steps 8c, 10c have angular surfaces, stress tends to concentrate on the steps 8c, 10c. However, in the present embodiment, the deepest part 16a of each slit 16 is close to the point at the highest extent of the corresponding valve seat 8c. Therefore, the stress concentrated on the steps 8c, 10c is effectively relieved by the slits 16. Further, the slits 16 are relatively shallow, which sufficiently maintains the strength of the cylinder head 2.
  • Thermal stress is especially concentrated at locations surrounded by the four valves (two intake valves and two exhaust valves) of the cylinder head 2 of a four-valve-type diesel engine.
  • the slits 16 effectively relieve such thermal stress.
  • the cylinder head 2 is made of aluminum alloy.
  • the thermal expansion rate of aluminum alloy is greater than that of cast iron, which results in relatively great thermal stress in the aluminum.
  • the thermal stress applied to the cylinder head 2 is great.
  • the slits 16 relieve the thermal stress applied to the cylinder head 2 and sufficiently maintain the strength of the cylinder head 2.
  • Fig. 5 is a cross-sectional view of a cylinder head 2 according to a second embodiment. Only differences from the first embodiment shown in Figs. 1-4 will now be described. Fig. 5 corresponds to Fig. 2 of the first embodiment.
  • the cylinder head 2 of Fig. 5 includes passages 22a, 24a, which connect the water jackets 22, 24 to other water jackets (not shown) of the cylinder block 11.
  • Each slit 16 is formed between the passages 22a, 24a.
  • the slits 16 of the second embodiment are shorter than the slits shown in Fig. 2 such that the slits 16 are not connected to the passages 22a, 24a.
  • the rest of the structure of the second embodiment is the same as that shown in Figs. 1-4.
  • the second embodiment has the following advantages in addition to the first embodiment shown in Figs. 1-4.
  • the slits 16 are separated from the passages 22a, 24a that are connected to the cylinder block 11. This prevents leakage of water, maintains the strength of the cylinder head 2, and relieves thermal stress.
  • the present invention can further be varied as follows.
  • the slits 16 are formed between the adjacent combustion chambers 15.
  • the slits 16 may be formed in other parts of the cylinder head 2.
  • the slits 16 may be formed on the cylinder head of a one-cylinder internal combustion engine.
  • the present invention may also be applied to gasoline engines.
  • a cylinder head (2) of an internal combustion engine is connected to a cylinder block (11) that has a cylinder bore (13).
  • a bottom surface (2a) faces the cylinder block (11).
  • the bottom surface (2a) has two ceiling surfaces (6).
  • the ceiling surfaces (6) and the cylinder bore (13) define a combustion chamber (15).
  • a slit (16) is formed on the bottom surface (2a) adjacent the ceiling surface (6) to mitigate thermal stress in the cylinder head (2).
  • the slit (16) has a deepest part (16a) located near a center of the ceiling surfaces (6).
  • the depth of the slit (16) decreases as the distance from the maximum depth part (16a) increases.
  • the slit (16) is separated from other spaces in the cylinder head (2). This cylinder head structure sufficiently mitigates thermal stress and maintains the strength of the cylinder head (2).

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
EP99123425A 1998-11-25 1999-11-24 Dispositif de culasse de moteur à explosion pour diminuer les contraintes thermiques Withdrawn EP1004765A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP10333818A JP2000161128A (ja) 1998-11-25 1998-11-25 内燃機関のシリンダヘッド熱応力緩和構造
JP33381898 1998-11-25

Publications (1)

Publication Number Publication Date
EP1004765A1 true EP1004765A1 (fr) 2000-05-31

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EP99123425A Withdrawn EP1004765A1 (fr) 1998-11-25 1999-11-24 Dispositif de culasse de moteur à explosion pour diminuer les contraintes thermiques

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EP (1) EP1004765A1 (fr)
JP (1) JP2000161128A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1519028A1 (fr) * 2003-09-24 2005-03-30 DaimlerChrysler AG Culasse d'un moteur à combustion interne
WO2007051217A2 (fr) * 2005-10-31 2007-05-10 Avl List Gmbh Moteur a combustion interne
AT501025B1 (de) * 2006-02-09 2007-12-15 Avl List Gmbh Brennkraftmaschine mit einem zylinderkopf
CN104131908A (zh) * 2014-08-12 2014-11-05 广西玉柴机器股份有限公司 气缸盖的消除机加工应力集中结构

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5066292B1 (ja) * 2012-02-28 2012-11-07 敏彦 辻 ２ストローク内燃機関
CN208959341U (zh) * 2015-06-19 2019-06-11 斗山英维高株式会社 发动机的缸头
WO2018033873A1 (fr) * 2016-08-19 2018-02-22 Tvs Motor Company Limited Culasse de moteur à combustion interne

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB456289A (en) * 1935-07-09 1936-11-06 Ass Equipment Co Ltd Improvements in or relating to cylinder-heads of internal combustion engines
GB1339226A (en) * 1971-03-12 1973-11-28 Daimler Benz Ag Cylinder housing of a reciprocating-piston engine
US4436066A (en) * 1979-05-23 1984-03-13 Fiat Veicoli Industriali S.P.A. Cylinder head for compression-ignition internal combustion engine
FR2654775A1 (fr) * 1989-11-22 1991-05-24 Peugeot Culasse pour moteur a combustion interne a inserts disposes a la coulee entre sieges de soupape.
EP0785352A1 (fr) * 1996-01-19 1997-07-23 Toyota Jidosha Kabushiki Kaisha Culasse pour un moteur à combustion interne à plusieurs cylindres

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB456289A (en) * 1935-07-09 1936-11-06 Ass Equipment Co Ltd Improvements in or relating to cylinder-heads of internal combustion engines
GB1339226A (en) * 1971-03-12 1973-11-28 Daimler Benz Ag Cylinder housing of a reciprocating-piston engine
US4436066A (en) * 1979-05-23 1984-03-13 Fiat Veicoli Industriali S.P.A. Cylinder head for compression-ignition internal combustion engine
FR2654775A1 (fr) * 1989-11-22 1991-05-24 Peugeot Culasse pour moteur a combustion interne a inserts disposes a la coulee entre sieges de soupape.
EP0785352A1 (fr) * 1996-01-19 1997-07-23 Toyota Jidosha Kabushiki Kaisha Culasse pour un moteur à combustion interne à plusieurs cylindres

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1519028A1 (fr) * 2003-09-24 2005-03-30 DaimlerChrysler AG Culasse d'un moteur à combustion interne
WO2007051217A2 (fr) * 2005-10-31 2007-05-10 Avl List Gmbh Moteur a combustion interne
WO2007051217A3 (fr) * 2005-10-31 2007-12-13 Avl List Gmbh Moteur a combustion interne
US20090320775A1 (en) * 2005-10-31 2009-12-31 Helmut Altendorfer Internal Combustion Engine
AT501025B1 (de) * 2006-02-09 2007-12-15 Avl List Gmbh Brennkraftmaschine mit einem zylinderkopf
CN104131908A (zh) * 2014-08-12 2014-11-05 广西玉柴机器股份有限公司 气缸盖的消除机加工应力集中结构

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