US20140305397A1 - Camshaft support structure - Google Patents
Camshaft support structure Download PDFInfo
- Publication number
- US20140305397A1 US20140305397A1 US14/349,738 US201114349738A US2014305397A1 US 20140305397 A1 US20140305397 A1 US 20140305397A1 US 201114349738 A US201114349738 A US 201114349738A US 2014305397 A1 US2014305397 A1 US 2014305397A1
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- United States
- Prior art keywords
- camshaft
- support bases
- cylinder head
- support
- internal combustion
- 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.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/46—Component parts, details, or accessories, not provided for in preceding subgroups
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
- F01L1/047—Camshafts
- F01L1/053—Camshafts overhead type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
- F01L1/047—Camshafts
- F01L2001/0476—Camshaft bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
- F01L1/047—Camshafts
- F01L1/053—Camshafts overhead type
- F01L2001/0537—Double overhead camshafts [DOHC]
Definitions
- the present invention relates to a camshaft support structure that includes support bases, which are mounted on the cylinder head of an internal combustion engine and support camshafts to be freely rotational.
- the weight of the internal combustion engine is reduced as compared to a structure in which an outer frame for connecting the support bases is provided, as in a ladder-frame camshaft housing, by the weight corresponding to the outer frame.
- Patent Document 1 Japanese Laid-Open Patent Publication No. 2010-209796
- the temperature of the cylinder head is increased by receiving heat of exhaust gas, causing the cylinder head to be thermally deformed. Since the support bases are arranged to abut against the cylinder head, the support bases are thermally deformed by receiving heat from the cylinder head. This deteriorates alignment of bearing portions, which are formed in the support bases and support the camshafts. As a result, problems may arise such as an increase in rotational sliding resistance of the camshafts.
- the amount of heat that the support bases receive from the cylinder head is reduced as compared to the structure with the ladder-frame camshaft housing by the amount corresponding to the outer frame.
- the thermal deformation amount of the support bases is thus reduced to some extent.
- the invention is applied to an internal combustion engine in which the exhaust gas temperature is further increased such as an internal combustion engine provided with a forced-induction device, the amount of heat that the support bases receive from the cylinder head is further increased. In this case, there are limitations in favorably reducing deterioration in the alignment of the bearing portions of the support bases.
- camshaft support structure that favorably reduces deterioration in the alignment of bearing portions of support bases, which support camshafts, due to engine operation.
- a camshaft support structure mounted on a cylinder head of an internal combustion engine includes support bases for supporting a camshaft to be freely rotational.
- the support bases are arranged apart from one another in an axial direction of the camshaft.
- Each support base has a bearing portion, which supports the camshaft, and a through hole, which extends in the axial direction of the camshaft.
- the through holes receive a rod, which restricts the bearing portions from being displaced from an arrangement position at which the bearing portions are located when the internal combustion engine is stopped and cold.
- the bearing portions of the support bases mounted on the cylinder head of the internal combustion engine support the camshaft to be freely rotational. Since the support bases are arranged apart from one another in the axial direction of the camshaft, the contact area between the support bases and the cylinder head is reduced as compared to the structure with an outer frame for connecting the support bases, such as a ladder-frame camshaft housing. This reduces the amount of heat received from the cylinder head, thus reducing thermal deformation of the support bases caused by the received heat.
- the support bases are restricted from being thermally deformed by the heat received from the cylinder head.
- the rod is assembled to the cylinder head together with the support bases in a state in which the rod is inserted in the through holes.
- the cylinder head is assembled to the cylinder block with head bolts.
- the top surface of the cylinder head is slightly distorted from a flat state due to the axial tightening force of the head bolts. The rod is thus maintained in a state pressed by the inner walls of the through holes, and secured to the support bases.
- the structure thus favorably reduces deterioration in the alignment of the bearing portions of the support bases, which support the camshaft, due to engine operation.
- the rod is preferably made of material having higher rigidity than the support bases. According to this embodiment, thermal deformation of the support bases is reduced in an appropriate manner.
- the rod may be made of stainless-steel, which has higher rigidity than the aluminum alloy.
- each support base preferably includes a receiving member, which is mounted on the cylinder head and receives the camshaft, and a cap member, which is mounted on a top surface of the receiving member and forms the bearing portion together with the receiving member.
- the through hole is preferably formed in the receiving member.
- the support bases preferably receive both an exhaust camshaft and an intake camshaft, which each serve as the camshaft, and the through holes are preferably formed closer to the exhaust camshaft than to the intake camshaft.
- the thermal deformation of the cylinder head is thus greater in the region closer to the exhaust camshaft.
- the through holes in which the rod is inserted are formed closer to the exhaust camshaft than to the intake camshaft. That is, the rod is arranged close to the region of the receiving members of the support bases where the amount of heat received from the cylinder head is great and the degree of thermal deformation is great. The region of the support bases in the vicinity of the exhaust camshaft where the amount of heat received from the cylinder head is great is thus restricted from being thermally deformed in an appropriate manner.
- the thermal deformation amount of the support bases caused by heat received from the cylinder head is great. Furthermore, in the internal combustion engine provided with a forced-induction device, since the pressure in the cylinders is higher than that without the forced-induction device, the cylinder head is significantly deformed by fluctuation of the pressure in the cylinders of the internal combustion engine. As a result, the deformation amount of the support bases mounted on the cylinder head is increased.
- FIG. 1 is a plan view illustrating a planar structure of an internal combustion engine according to a first embodiment of the present invention as viewed from above an exhaust camshaft and an intake camshaft;
- FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1 , illustrating a cross-sectional structure of the internal combustion engine
- FIG. 3 is a side view schematically illustrating a side structure of the top surface of the cylinder head and the support bases mounted on the top surface in the longitudinal direction of the cylinder head.
- a camshaft support structure of a double overhead camshaft (DOHC) inline 4-cylinder internal combustion engine according to one embodiment of the present invention will now be described with reference to FIGS. 1 to 3 .
- the internal combustion engine of the present embodiment is provided with an exhaust driven forced-induction device.
- FIG. 1 shows a planar structure of an internal combustion engine as viewed from above an exhaust camshaft and an intake camshaft.
- FIG. 2 shows a cross-sectional structure of the internal combustion engine taken along line A-A of FIG. 1 .
- a cylinder head 1 which is provided with a valve mechanism including exhaust valves and intake valves, is provided on the top surface of a cylinder block 2 as shown in FIG. 2 .
- the cylinder block 2 and the cylinder head 1 are tightened with head bolts 3 in a known manner (see FIGS. 2 and 3 ).
- An exhaust camshaft 5 provided with exhaust cams 51 for opening and closing the exhaust valves and an intake camshaft 6 provided with intake cams 61 for opening and closing the intake valves are arranged on a top surface 1 a of the cylinder head 1 to be parallel to each other. More specifically, five support bases 4 for supporting the camshafts 5 , 6 to be freely rotational are mounted on the top surface 1 a of the cylinder head 1 . Only one of the support bases 4 is shown in FIG. 2 .
- the support bases 4 are arranged apart from one another in an axial direction L of the camshafts 5 , 6 as shown in FIG. 1 . More specifically, the support bases 4 are arranged to be perpendicular to the axial direction L of the camshafts 5 , 6 .
- Each of the support bases 4 includes a receiving member 41 located on the top surface 1 a of the cylinder head 1 , and an exhaust side cap member 42 and an intake side cap member 43 , which are located on the top surface of the receiving member 41 as shown in FIG. 2 .
- Semi-circular lower recesses 41 b, 41 c are formed on the top surface of each receiving member 41 at positions corresponding to the camshafts 5 , 6 .
- a semicircular upper recess 42 b is formed on the bottom surface of each exhaust side cap member 42 at a position corresponding to the associated lower recess 41 b.
- Each lower recess 41 b and the associated upper recess 42 b form a circular bearing portion 45 b, which supports one of cam journals 5 a of the exhaust camshaft 5 (see FIG. 1 ).
- each intake side cap member 43 is formed on the bottom surface of each intake side cap member 43 at a position corresponding to the associated lower recess 41 c.
- Each lower recess 41 c and the associated upper recess 43 c form a circular bearing portion 45 c, which supports one of cam journals 6 a of the intake camshaft 6 (see FIG. 1 ).
- each exhaust side cap member 42 and the associated receiving member 41 are formed in an axial direction C of the cylinders with the exhaust camshaft 5 located in between.
- the receiving member 41 and the exhaust side cap member 42 are tightened to the cylinder head 1 with bolts 44 L, 44 S inserted in the bolt holes.
- each intake side cap member 43 and the associated receiving member 41 are coupled to the cylinder head 1 with other bolts 44 L in the same manner as each exhaust side cap member 42 and the associated receiving member 41 .
- the cylinder head 1 In a state in which the support bases 4 are mounted on the cylinder head 1 with the bolts 44 L, 44 S, the cylinder head 1 is assembled to the cylinder block 2 with the head bolts 3 .
- the cylinder head 1 , the cylinder block 2 , and the support bases 4 are all made of an aluminum alloy.
- a through hole 41 d which extends in the axial direction L of the camshafts 5 , 6 , is formed in each receiving member 41 as shown in FIG. 2 .
- Each through hole 41 d is formed at a position closer to a center position Pex of the exhaust camshaft 5 than to a middle position Pc between the center position Pex of the exhaust camshaft 5 and a center position Pin of the intake camshaft 6 in a direction perpendicular to the axial direction L of the camshafts 5 , 6 .
- the through holes 41 d are formed closer to the exhaust camshaft 5 than to the intake camshaft 6 .
- a rod 7 made of stainless-steel is inserted in the through holes 41 d. That is, the rod 7 is made of material having higher rigidity than the support bases 4 .
- the outer diameter of the rod 7 is slightly smaller than the inner diameter of the through holes 41 d.
- the bolts 44 S located closer to the rod 7 than to the exhaust camshaft 5 are shorter than the other bolts 44 L so as not to interfere with the rod 7 .
- the camshafts 5 , 6 are supported to be freely rotational by the bearing portions 45 b, 45 c of the five support bases 4 mounted on the cylinder head 1 . Since the support bases 4 are located separate from one another in the axial direction L of the camshafts 5 , 6 , the contact area between the support bases 4 and the cylinder head 1 is reduced as compared to a case in which an outer frame for connecting the support bases is provided, as in a ladder-frame camshaft housing. The amount of heat received from the cylinder head 1 is thus reduced, which reduces thermal deformation of the support bases 4 caused by receiving heat.
- the temperature of exhaust gas is increased as compared to the internal combustion engine without a forced-induction device.
- This increases the thermal deformation amount of the support bases 4 caused by receiving heat from the cylinder head 1 .
- the cylinder head 1 is deformed significantly as the pressure in the cylinders of the internal combustion engine fluctuates. The deformation amount of the support bases 4 mounted on the cylinder head 1 is consequently increased.
- the alignment of the bearing portions 45 b, 45 c in the support bases 4 is likely to deteriorate due to engine operation although with the camshaft support structure of the present embodiment that does not include the outer frame for the support bases 4 .
- the support bases 4 are favorably restricted from being thermally deformed due to heat received from the cylinder head 1 .
- the through holes 41 d in which the rod 7 is inserted are formed at positions closer to the exhaust camshaft 5 than to the intake camshaft 6 . That is, the rod 7 is arranged in the vicinity of the regions in the receiving members 41 of the support bases 4 where the amount of heat received from the cylinder head 1 is great and the degree of thermal deformation is great. Thermal deformation of the receiving members 41 in the vicinity of the exhaust camshaft 5 is thus reduced in an appropriate manner.
- the rod 7 is assembled to the cylinder head 1 together with the support bases 4 in a state in which the rod 7 is inserted in the through holes 41 d.
- the cylinder head 1 is further assembled to the cylinder block 2 with the head bolts 3 in a state in which the support bases 4 and the rod 7 are assembled to the cylinder head 1 .
- the top surface 1 a of the cylinder head 1 is slightly distorted from a flat state due to the axial tightening force of the head bolts 3 as shown in FIG. 3 .
- the rod 7 is thus maintained in a state pressed by the inner walls of the through holes 41 d, and secured to the support bases 4 .
- the distortion of the top surface 1 a of the cylinder head 1 is exaggerated and the rod 7 is omitted in FIG. 3 .
- the camshaft support structure of the present embodiment as described above has the following advantages.
- the support bases 4 are arranged apart from one another in the axial direction L of the camshafts 5 , 6 . Furthermore, the bearing portions 45 b, 45 c, which support the camshafts 5 , 6 , and the through holes 41 d, which extend in the axial direction L of the camshafts 5 , 6 , are formed in the support bases 4 .
- the rod 7 is inserted in the through holes 41 d to restrict the bearing portions 45 b, 45 c from being displaced from the arrangement position at which the bearing portions 45 b, 45 c are located when the internal combustion engine is stopped and cold.
- the alignment of the bearing portions 45 b, 45 c is favorably restricted from deteriorating due to engine operation.
- the state in which the internal combustion engine is stopped and cold refers to a state in which operation of the internal combustion engine is stopped and the influence of heat caused by the previous engine operation can be ignored.
- the rod 7 is made of material having higher rigidity than the support bases 4 . More specifically, the support bases 4 are made of an aluminum alloy, and the rod 7 is made of stainless-steel, which has higher rigidity than the aluminum alloy. With this configuration, thermal deformation of the support bases 4 is reduced in an appropriate manner.
- the through holes 41 d are formed closer to the exhaust camshaft 5 than to the intake camshaft 6 . This structure appropriately reduces thermal deformation of the receiving members 41 in the vicinity of the exhaust camshaft 5 where the amount of heat received from the cylinder head 1 is great.
- camshaft support structure of the present invention is not limited to the structure illustrated in the above described embodiment, but may be modified as follows.
- the present invention is applied to an internal combustion engine provided with an exhaust driven forced-induction device, that is, a turbocharger.
- the present invention may, however, be applied to an internal combustion engine provided with an engine driven forced-induction device, or a supercharger.
- the present invention is applied to an internal combustion engine provided with a forced-induction device.
- the present invention is not only applied to an internal combustion engine provided with a forced-induction device, but may be applied to an internal combustion engine without a forced-induction device.
- the alignment of the bearing portions of the support bases is favorably restricted from deteriorating due to engine operation in the same manner as the above-described embodiment.
- the through holes 41 d be formed closer to the exhaust camshaft 5 than to the intake camshaft 6 to prevent thermal deformation of the receiving members 41 in the vicinity of the exhaust camshaft 5 where the amount of heat received from the cylinder head 1 is great.
- the present invention is not limited to this, but through holes may be formed at, for example, the middle position Pc between the exhaust camshaft 5 and the intake camshaft 6 . In this case also, thermal deformation of the receiving members is restricted to some extent.
- one through hole 41 d is formed in each of the support bases 4 .
- two or more through holes may be formed in each of the support bases 4 , and two or more rods may be provided corresponding to the number of the through holes. This further reduces thermal deformation of the support bases.
- the rod 7 made of stainless-steel is illustrated in the above-described embodiment, but the rod may be made of any material that has higher rigidity than the support bases.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
- Cylinder Crankcases Of Internal Combustion Engines (AREA)
Abstract
Support bases for supporting camshafts in a rotatable manner are mounted on the cylinder head of an internal combustion engine. The support bases are provided so as to be separated from each other in the axial direction of the camshafts. Each of the support bases comprises bearing portions which support the camshafts and a through-hole which extends in the axial direction of the camshafts. A rod is inserted through the through-holes, and the rod restricts the bearing portions from being displaced from positions at which the bearing portions are located while the internal combustion engine is stopped and cold.
Description
- This application is a national phase application of International Application No. PCT/JP2011/073339, filed Oct. 11, 2011, the content of which is incorporated herein by reference.
- The present invention relates to a camshaft support structure that includes support bases, which are mounted on the cylinder head of an internal combustion engine and support camshafts to be freely rotational.
- Conventionally, this type of camshaft support structure has been proposed in, for example,
Patent Document 1. According to the camshaft support structure disclosed inPatent Document 1, the support bases, which support the camshafts to be freely rotational, are provided apart from one another in the axial direction of the camshafts. - With this structure, the weight of the internal combustion engine is reduced as compared to a structure in which an outer frame for connecting the support bases is provided, as in a ladder-frame camshaft housing, by the weight corresponding to the outer frame.
- Patent Document 1: Japanese Laid-Open Patent Publication No. 2010-209796
- When an engine is operated, the temperature of the cylinder head is increased by receiving heat of exhaust gas, causing the cylinder head to be thermally deformed. Since the support bases are arranged to abut against the cylinder head, the support bases are thermally deformed by receiving heat from the cylinder head. This deteriorates alignment of bearing portions, which are formed in the support bases and support the camshafts. As a result, problems may arise such as an increase in rotational sliding resistance of the camshafts.
- According to the structure disclosed in
Patent Document 1, the amount of heat that the support bases receive from the cylinder head is reduced as compared to the structure with the ladder-frame camshaft housing by the amount corresponding to the outer frame. The thermal deformation amount of the support bases is thus reduced to some extent. If, however, the invention is applied to an internal combustion engine in which the exhaust gas temperature is further increased such as an internal combustion engine provided with a forced-induction device, the amount of heat that the support bases receive from the cylinder head is further increased. In this case, there are limitations in favorably reducing deterioration in the alignment of the bearing portions of the support bases. - Accordingly, it is an objective of the present invention to provide a camshaft support structure that favorably reduces deterioration in the alignment of bearing portions of support bases, which support camshafts, due to engine operation.
- Means for solving the above issues and advantages thereof will now be discussed.
- To achieve the foregoing objective and in accordance with one aspect of the present invention, a camshaft support structure mounted on a cylinder head of an internal combustion engine includes support bases for supporting a camshaft to be freely rotational. The support bases are arranged apart from one another in an axial direction of the camshaft. Each support base has a bearing portion, which supports the camshaft, and a through hole, which extends in the axial direction of the camshaft. The through holes receive a rod, which restricts the bearing portions from being displaced from an arrangement position at which the bearing portions are located when the internal combustion engine is stopped and cold.
- With this structure, the bearing portions of the support bases mounted on the cylinder head of the internal combustion engine support the camshaft to be freely rotational. Since the support bases are arranged apart from one another in the axial direction of the camshaft, the contact area between the support bases and the cylinder head is reduced as compared to the structure with an outer frame for connecting the support bases, such as a ladder-frame camshaft housing. This reduces the amount of heat received from the cylinder head, thus reducing thermal deformation of the support bases caused by the received heat.
- Furthermore, with this structure, since the rod is inserted in the through holes formed in the support bases, the support bases are restricted from being thermally deformed by the heat received from the cylinder head.
- The rod is assembled to the cylinder head together with the support bases in a state in which the rod is inserted in the through holes. The cylinder head is assembled to the cylinder block with head bolts. The top surface of the cylinder head is slightly distorted from a flat state due to the axial tightening force of the head bolts. The rod is thus maintained in a state pressed by the inner walls of the through holes, and secured to the support bases.
- The structure thus favorably reduces deterioration in the alignment of the bearing portions of the support bases, which support the camshaft, due to engine operation.
- The rod is preferably made of material having higher rigidity than the support bases. According to this embodiment, thermal deformation of the support bases is reduced in an appropriate manner. In a case in which the support bases are made of aluminum alloy, for example, the rod may be made of stainless-steel, which has higher rigidity than the aluminum alloy.
- As a specific structure of the support bases, each support base preferably includes a receiving member, which is mounted on the cylinder head and receives the camshaft, and a cap member, which is mounted on a top surface of the receiving member and forms the bearing portion together with the receiving member. In this case, the through hole is preferably formed in the receiving member.
- In this case, the support bases preferably receive both an exhaust camshaft and an intake camshaft, which each serve as the camshaft, and the through holes are preferably formed closer to the exhaust camshaft than to the intake camshaft.
- In the internal combustion engine, high-temperature exhaust gas is discharged to an exhaust passage through exhaust valves. The thermal deformation of the cylinder head is thus greater in the region closer to the exhaust camshaft. In this point, according to the above embodiment, the through holes in which the rod is inserted are formed closer to the exhaust camshaft than to the intake camshaft. That is, the rod is arranged close to the region of the receiving members of the support bases where the amount of heat received from the cylinder head is great and the degree of thermal deformation is great. The region of the support bases in the vicinity of the exhaust camshaft where the amount of heat received from the cylinder head is great is thus restricted from being thermally deformed in an appropriate manner.
- In the internal combustion engine provided with a forced-induction device, since the temperature of exhaust gas is higher than that without the forced-induction device, the thermal deformation amount of the support bases caused by heat received from the cylinder head is great. Furthermore, in the internal combustion engine provided with a forced-induction device, since the pressure in the cylinders is higher than that without the forced-induction device, the cylinder head is significantly deformed by fluctuation of the pressure in the cylinders of the internal combustion engine. As a result, the deformation amount of the support bases mounted on the cylinder head is increased. As described above, in the internal combustion engine provided with a forced-induction device, although with the camshaft support structure that does not include the outer frame for the support bases, the alignment of the bearing portions of the support bases is likely to deteriorate due to engine operation. Applying the present invention to such an internal combustion engine favorably reduces deterioration in the alignment of the bearing portions of the support bases due to engine operation.
-
FIG. 1 is a plan view illustrating a planar structure of an internal combustion engine according to a first embodiment of the present invention as viewed from above an exhaust camshaft and an intake camshaft; -
FIG. 2 is a cross-sectional view taken along line A-A ofFIG. 1 , illustrating a cross-sectional structure of the internal combustion engine; and -
FIG. 3 is a side view schematically illustrating a side structure of the top surface of the cylinder head and the support bases mounted on the top surface in the longitudinal direction of the cylinder head. - A camshaft support structure of a double overhead camshaft (DOHC) inline 4-cylinder internal combustion engine according to one embodiment of the present invention will now be described with reference to
FIGS. 1 to 3 . The internal combustion engine of the present embodiment is provided with an exhaust driven forced-induction device. -
FIG. 1 shows a planar structure of an internal combustion engine as viewed from above an exhaust camshaft and an intake camshaft.FIG. 2 shows a cross-sectional structure of the internal combustion engine taken along line A-A ofFIG. 1 . - A
cylinder head 1, which is provided with a valve mechanism including exhaust valves and intake valves, is provided on the top surface of acylinder block 2 as shown inFIG. 2 . Thecylinder block 2 and thecylinder head 1 are tightened withhead bolts 3 in a known manner (seeFIGS. 2 and 3 ). - An
exhaust camshaft 5 provided withexhaust cams 51 for opening and closing the exhaust valves and anintake camshaft 6 provided withintake cams 61 for opening and closing the intake valves are arranged on a top surface 1 a of thecylinder head 1 to be parallel to each other. More specifically, fivesupport bases 4 for supporting thecamshafts cylinder head 1. Only one of the support bases 4 is shown inFIG. 2 . - The support bases 4 are arranged apart from one another in an axial direction L of the
camshafts FIG. 1 . More specifically, thesupport bases 4 are arranged to be perpendicular to the axial direction L of thecamshafts - Each of the support bases 4 includes a receiving
member 41 located on the top surface 1 a of thecylinder head 1, and an exhaustside cap member 42 and an intakeside cap member 43, which are located on the top surface of the receivingmember 41 as shown inFIG. 2 . Semi-circularlower recesses 41 b, 41 c are formed on the top surface of each receivingmember 41 at positions corresponding to thecamshafts - A semicircular upper recess 42 b is formed on the bottom surface of each exhaust
side cap member 42 at a position corresponding to the associatedlower recess 41 b. Eachlower recess 41 b and the associated upper recess 42 b form acircular bearing portion 45 b, which supports one ofcam journals 5 a of the exhaust camshaft 5 (seeFIG. 1 ). - Furthermore, a semicircular
upper recess 43 c is formed on the bottom surface of each intakeside cap member 43 at a position corresponding to the associated lower recess 41 c. Each lower recess 41 c and the associatedupper recess 43 c form acircular bearing portion 45 c, which supports one ofcam journals 6 a of the intake camshaft 6 (seeFIG. 1 ). - Two bolt holes are formed in each exhaust
side cap member 42 and the associated receivingmember 41 in an axial direction C of the cylinders with theexhaust camshaft 5 located in between. The receivingmember 41 and the exhaustside cap member 42 are tightened to thecylinder head 1 withbolts 44L, 44S inserted in the bolt holes. - Furthermore, each intake
side cap member 43 and the associated receivingmember 41 are coupled to thecylinder head 1 withother bolts 44L in the same manner as each exhaustside cap member 42 and the associated receivingmember 41. - In a state in which the
support bases 4 are mounted on thecylinder head 1 with thebolts 44L, 44S, thecylinder head 1 is assembled to thecylinder block 2 with thehead bolts 3. Thecylinder head 1, thecylinder block 2, and thesupport bases 4 are all made of an aluminum alloy. - In the present embodiment, a through
hole 41 d, which extends in the axial direction L of thecamshafts member 41 as shown inFIG. 2 . Each throughhole 41 d is formed at a position closer to a center position Pex of theexhaust camshaft 5 than to a middle position Pc between the center position Pex of theexhaust camshaft 5 and a center position Pin of theintake camshaft 6 in a direction perpendicular to the axial direction L of thecamshafts holes 41 d are formed closer to theexhaust camshaft 5 than to theintake camshaft 6. - A
rod 7 made of stainless-steel is inserted in the throughholes 41 d. That is, therod 7 is made of material having higher rigidity than the support bases 4. In the present embodiment, the outer diameter of therod 7 is slightly smaller than the inner diameter of the throughholes 41 d. The bolts 44S located closer to therod 7 than to theexhaust camshaft 5 are shorter than theother bolts 44L so as not to interfere with therod 7. - Operation of the present embodiment will now be described.
- The
camshafts portions support bases 4 mounted on thecylinder head 1. Since thesupport bases 4 are located separate from one another in the axial direction L of thecamshafts support bases 4 and thecylinder head 1 is reduced as compared to a case in which an outer frame for connecting the support bases is provided, as in a ladder-frame camshaft housing. The amount of heat received from thecylinder head 1 is thus reduced, which reduces thermal deformation of thesupport bases 4 caused by receiving heat. - Since forced induction is performed by the forced-induction device in the internal combustion engine of the present embodiment, the temperature of exhaust gas is increased as compared to the internal combustion engine without a forced-induction device. This increases the thermal deformation amount of the
support bases 4 caused by receiving heat from thecylinder head 1. Furthermore, since the pressure in the cylinders is also increased as compared to the internal combustion engine without the forced-induction device, thecylinder head 1 is deformed significantly as the pressure in the cylinders of the internal combustion engine fluctuates. The deformation amount of thesupport bases 4 mounted on thecylinder head 1 is consequently increased. As described above, in the internal combustion engine provided with the forced-induction device, the alignment of the bearingportions - In this respect, since the
rod 7 is inserted in the throughholes 41 d formed in thesupport bases 4 in the present embodiment, thesupport bases 4 are favorably restricted from being thermally deformed due to heat received from thecylinder head 1. - Furthermore, in the internal combustion engine, high-temperature exhaust gas is discharged to the exhaust passage through the exhaust valves. Thermal deformation of the
cylinder head 1 is thus increased toward the region close to theexhaust camshaft 5. In this respect, with the above-mentioned structure, the throughholes 41 d in which therod 7 is inserted are formed at positions closer to theexhaust camshaft 5 than to theintake camshaft 6. That is, therod 7 is arranged in the vicinity of the regions in the receivingmembers 41 of thesupport bases 4 where the amount of heat received from thecylinder head 1 is great and the degree of thermal deformation is great. Thermal deformation of the receivingmembers 41 in the vicinity of theexhaust camshaft 5 is thus reduced in an appropriate manner. - Furthermore, the
rod 7 is assembled to thecylinder head 1 together with thesupport bases 4 in a state in which therod 7 is inserted in the throughholes 41 d. Thecylinder head 1 is further assembled to thecylinder block 2 with thehead bolts 3 in a state in which thesupport bases 4 and therod 7 are assembled to thecylinder head 1. In this embodiment, the top surface 1 a of thecylinder head 1 is slightly distorted from a flat state due to the axial tightening force of thehead bolts 3 as shown inFIG. 3 . Therod 7 is thus maintained in a state pressed by the inner walls of the throughholes 41 d, and secured to the support bases 4. For the illustrative purposes, the distortion of the top surface 1 a of thecylinder head 1 is exaggerated and therod 7 is omitted inFIG. 3 . - The camshaft support structure of the present embodiment as described above has the following advantages.
- (1) The support bases 4 are arranged apart from one another in the axial direction L of the
camshafts portions camshafts holes 41 d, which extend in the axial direction L of thecamshafts rod 7 is inserted in the throughholes 41 d to restrict the bearingportions portions camshafts portions - (2) The
rod 7 is made of material having higher rigidity than the support bases 4. More specifically, thesupport bases 4 are made of an aluminum alloy, and therod 7 is made of stainless-steel, which has higher rigidity than the aluminum alloy. With this configuration, thermal deformation of the support bases 4 is reduced in an appropriate manner. - (3) The through
holes 41 d are formed closer to theexhaust camshaft 5 than to theintake camshaft 6. This structure appropriately reduces thermal deformation of the receivingmembers 41 in the vicinity of theexhaust camshaft 5 where the amount of heat received from thecylinder head 1 is great. - The camshaft support structure of the present invention is not limited to the structure illustrated in the above described embodiment, but may be modified as follows.
- In the above-described embodiment, the present invention is applied to an internal combustion engine provided with an exhaust driven forced-induction device, that is, a turbocharger. The present invention may, however, be applied to an internal combustion engine provided with an engine driven forced-induction device, or a supercharger.
- In the above-described embodiment and the modified embodiment, the present invention is applied to an internal combustion engine provided with a forced-induction device. The present invention, however, is not only applied to an internal combustion engine provided with a forced-induction device, but may be applied to an internal combustion engine without a forced-induction device. In this case, although the amount of heat the support bases receive from the cylinder head is small as compared to that received by the engine provided with the forced-induction device, the alignment of the bearing portions of the support bases is favorably restricted from deteriorating due to engine operation in the same manner as the above-described embodiment.
- As in the above-described embodiment, it is preferable that the through
holes 41 d be formed closer to theexhaust camshaft 5 than to theintake camshaft 6 to prevent thermal deformation of the receivingmembers 41 in the vicinity of theexhaust camshaft 5 where the amount of heat received from thecylinder head 1 is great. The present invention, however, is not limited to this, but through holes may be formed at, for example, the middle position Pc between theexhaust camshaft 5 and theintake camshaft 6. In this case also, thermal deformation of the receiving members is restricted to some extent. - In the above-described embodiment, one through
hole 41 d is formed in each of the support bases 4. Instead, two or more through holes may be formed in each of the support bases 4, and two or more rods may be provided corresponding to the number of the through holes. This further reduces thermal deformation of the support bases. - The
rod 7 made of stainless-steel is illustrated in the above-described embodiment, but the rod may be made of any material that has higher rigidity than the support bases. - 1 . . . cylinder head, 1 a . . . top surface, 2 . . . cylinder block, 3 . . . head bolt, 4 . . . support base, 41 . . . receiving member, 41 a . . . abutment surface, 41 b, 41 c . . . lower recesses, 41 d . . . through hole, 42 . . . exhaust side cap member, 42 b . . . upper recess, 43 . . . intake side cap member, 43 c . . . lower recess, 44 . . . bolt, 45 b, 45 c . . . bearing portions, 5 . . . exhaust camshaft, 5 a . . . cam journal, 51 . . . exhaust cam, 6 . . . intake camshaft, 6 a . . . cam journal, 61 . . . intake cam, 7 . . . rod.
Claims (5)
1.-5. (canceled)
6. A camshaft support structure mounted on a cylinder head of an internal combustion engine, the camshaft support structure comprising support bases for supporting both an exhaust camshaft and an intake camshaft to be freely rotational, the structure comprising:
the support bases are arranged apart from one another in an axial direction of the exhaust camshaft and the intake camshaft;
each support base has bearing portions, which support the exhaust camshaft and the intake camshaft, and a through hole, which is formed closer to the exhaust camshaft than to the intake camshaft and extends in the axial direction; and
the through holes receive a rod, which restricts the bearing portions from being displaced from an arrangement position at which the bearing portions are located when the internal combustion engine is stopped and cold.
7. The camshaft support structure according to claim 6 , wherein the rod is made of material having higher rigidity than the support bases.
8. The camshaft support structure according to claim 6 , wherein
each support base includes a receiving member, which is mounted on the cylinder head and receives the exhaust camshaft and the intake camshaft, and cap members, which are mounted on a top surface of the receiving member and form the bearing portions together with the receiving member, and
the through hole is formed in the receiving member.
9. The camshaft support structure according to claim 6 , wherein the internal combustion engine includes a forced-induction device.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2011/073339 WO2013054395A1 (en) | 2011-10-11 | 2011-10-11 | Camshaft support structure |
Publications (1)
Publication Number | Publication Date |
---|---|
US20140305397A1 true US20140305397A1 (en) | 2014-10-16 |
Family
ID=48081474
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/349,738 Abandoned US20140305397A1 (en) | 2011-10-11 | 2011-10-11 | Camshaft support structure |
Country Status (5)
Country | Link |
---|---|
US (1) | US20140305397A1 (en) |
EP (1) | EP2767680A4 (en) |
JP (1) | JP5742956B2 (en) |
CN (1) | CN103874830A (en) |
WO (1) | WO2013054395A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10309339B2 (en) * | 2015-05-25 | 2019-06-04 | Nissan Motor Co., Ltd. | Internal combustion engine |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP6631176B2 (en) | 2015-11-09 | 2020-01-15 | いすゞ自動車株式会社 | Cylinder head structure of internal combustion engine and internal combustion engine |
Citations (3)
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US20090013949A1 (en) * | 2006-01-19 | 2009-01-15 | Toyota Jidosha Kabushiki Kaisha | Camshaft Support Structure of an Internal Combustion Engine |
US20090101096A1 (en) * | 2007-10-19 | 2009-04-23 | Honda Motor Co., Ltd. | Valve system for overhead-camshaft-type internal combustion engine, and engine incorporating same |
JP2010209796A (en) * | 2009-03-10 | 2010-09-24 | Toyota Motor Corp | Camshaft supporting structure |
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JPS60531B2 (en) * | 1981-10-05 | 1985-01-08 | マツダ株式会社 | Engine camshaft bearing structure |
JPS6127905U (en) * | 1984-07-25 | 1986-02-19 | 本田技研工業株式会社 | OHC type internal combustion engine |
DE3641129C1 (en) * | 1986-12-02 | 1987-07-30 | Daimler Benz Ag | Device for mounting two camshafts in the cylinder head of a multi-cylinder in-line internal combustion engine |
JPH11351243A (en) * | 1998-06-05 | 1999-12-24 | Hitachi Ltd | Thrust bearing |
JP4365373B2 (en) * | 2006-01-19 | 2009-11-18 | トヨタ自動車株式会社 | Camshaft support structure for internal combustion engine |
JP4144625B2 (en) * | 2006-01-19 | 2008-09-03 | トヨタ自動車株式会社 | Camshaft support structure for internal combustion engine |
JP4218715B2 (en) * | 2006-08-31 | 2009-02-04 | トヨタ自動車株式会社 | cylinder head |
JP2008133749A (en) * | 2006-11-27 | 2008-06-12 | Toyota Motor Corp | Bearing structure and method for cam shaft |
JP2008303856A (en) * | 2007-06-11 | 2008-12-18 | Toyota Motor Corp | Engine structure and method of controlling thermal deformation in engine |
-
2011
- 2011-10-11 US US14/349,738 patent/US20140305397A1/en not_active Abandoned
- 2011-10-11 WO PCT/JP2011/073339 patent/WO2013054395A1/en active Application Filing
- 2011-10-11 JP JP2013538353A patent/JP5742956B2/en not_active Expired - Fee Related
- 2011-10-11 CN CN201180074058.5A patent/CN103874830A/en active Pending
- 2011-10-11 EP EP11873837.6A patent/EP2767680A4/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US20090013949A1 (en) * | 2006-01-19 | 2009-01-15 | Toyota Jidosha Kabushiki Kaisha | Camshaft Support Structure of an Internal Combustion Engine |
US20090101096A1 (en) * | 2007-10-19 | 2009-04-23 | Honda Motor Co., Ltd. | Valve system for overhead-camshaft-type internal combustion engine, and engine incorporating same |
JP2010209796A (en) * | 2009-03-10 | 2010-09-24 | Toyota Motor Corp | Camshaft supporting structure |
Non-Patent Citations (1)
Title |
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Machine Translation of JP 2010209796 A PDF File name: "JP2010209796A_Machine_Translation.pdf" * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10309339B2 (en) * | 2015-05-25 | 2019-06-04 | Nissan Motor Co., Ltd. | Internal combustion engine |
Also Published As
Publication number | Publication date |
---|---|
WO2013054395A1 (en) | 2013-04-18 |
JP5742956B2 (en) | 2015-07-01 |
JPWO2013054395A1 (en) | 2015-03-30 |
CN103874830A (en) | 2014-06-18 |
EP2767680A1 (en) | 2014-08-20 |
EP2767680A4 (en) | 2015-09-30 |
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Owner name: TOYOTA JIDOSHA KABUSHIKI KAISHA, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:YANASE, YOSHINORI;REEL/FRAME:032602/0233 Effective date: 20140204 |
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