Patent Application
20130340703
This disclosure relates to cylinder heads for internal combustion engines. More specifically, this disclosure relates to a cylinder head configuration that has a greater structural efficiency than conventional cylinder heads. The structural efficiency of a cylinder head relates to a cylinder pressure capability for a given mass of the cylinder head.
The fuel efficiency of vehicles has been increasing in response to government regulations and customer expectations. One way to increase fuel efficiency of a vehicle is to decrease the weight of the vehicle. For vehicles propelled by an internal combustion engine, the weight of the internal combustion engine can represent a significant portion of the weight of the vehicle. Thus, an opportunity to reduce the weight of an internal combustion engine represents an opportunity to improve fuel efficiency of an associated vehicle. Because of the size and complexity of internal combustion engines, there may remain unexpected and unanticipated opportunities to reduce the weight of such engines.
In addition to reducing weight, if a cylinder head of an internal combustion engine could be configured to increase a combustion pressure capability while reducing weight, increased combustion pressure could be realized. Increasing combustion pressure causes more thorough or improved combustion of fuel, which will reduce emissions and increase engine efficiency.
This disclosure provides a cylinder head for an internal combustion engine. The cylinder head comprises a bottom deck, a component bore, a bolt boss, a valve boss, and a first rib. The component bore has a wall extending longitudinally from the bottom deck. The bolt boss extends longitudinally from the bottom deck and is in a position at a first radial distance from the component bore. The valve boss is in a position at a second radial distance from the component bore. The second radial distance is less than the first radial distance. The first rib extends longitudinally upward from the bottom deck, connecting to the bolt boss at a first end, and extends to a location on an upper portion of the bolt boss.
This disclosure also provides a cylinder head for an internal combustion engine. The cylinder head comprises a bottom deck, a component bore, a bolt boss, a valve boss, an intake passage, an exhaust passage, and a first rib. The component bore has a component bore wall extending longitudinally from the bottom deck. The bolt boss extends longitudinally from the bottom deck and is in a position at a first radial distance from the component bore. The valve boss is in a position at a second radial distance from the component bore. The second radial distance is less than the first radial distance. The intake passage is formed in the cylinder head and the intake passage includes an intake passage wall. The exhaust passage is formed in the cylinder head and the exhaust passage includes an exhaust passage wall. The first rib extends longitudinally upward from one of the intake passage wall and the exhaust passage wall to connect to a location on the component bore wall.
This disclosure also provides a cylinder head for an internal combustion engine. The cylinder head comprises a bottom deck, at least one intake passage, at least one exhaust passage, a component bore, a plurality of bolt bosses, a plurality of valve bosses, and a plurality of ribs. The intake passage includes an intake passage wall. The exhaust passage includes an exhaust passage wall. The component bore includes a component bore wall and a component bore center extending longitudinally from the bottom deck. Each bolt boss of the plurality of bolt bosses extends longitudinally from the bottom deck and includes a bolt boss center. Each of the plurality of bolt bosses is positioned at spaced angles about the component bore at one or more first radial distances from the component bore. Each valve boss of the plurality of valve bosses has a valve boss center and extends longitudinally from one intake passage or one exhaust passage wall. Each one of the plurality of valve bosses is positioned at spaced angles about the component bore at one or more second radial distances, the second radial distances being less than the first radial distances. The plurality of ribs extends longitudinally from at least one of the group consisting of the bottom deck, the intake passage wall, and the exhaust passage wall and the plurality of ribs connects to at least one of the group consisting of the plurality of bolt bosses, the plurality of valve bosses, and the component bore wall.
Advantages and features of the embodiments of this disclosure will become more apparent from the following detailed description of exemplary embodiments when viewed in conjunction with the accompanying drawings.
Referring to
Engine 10 further includes a piston 22 positioned for reciprocal movement within each cylinder liner 18 in association with each combustion chamber 14. Piston 22 may be any type of piston so long as it contains the features identified hereinbelow necessary for accomplishing the present disclosure. For example, piston 22 may be an articulated piston or a single piece piston.
An upper surface or top face 24 of piston 22 cooperates with cylinder head 20 and the portion of cylinder liner 18 extending between cylinder head 20 and piston 22 to define combustion chamber 14. Although not specifically illustrated, piston 22 connects to a crankshaft of engine 10 by way of a connecting rod 26 that causes piston 22 to reciprocate along a rectilinear path within cylinder liner 18 as the engine crankshaft rotates.
Engine 10 of the present disclosure may be a four-cycle compression ignition (diesel) engine employing direct injection of fuel into each combustion chamber 14. An intake passage 28 formed in cylinder head 20 selectively directs intake air into combustion chamber 14 by means of a pair of intake poppet valves 30 positioned in cylinder head 20, only one of which is illustrated in
At the uppermost, TDC position shown in
Engine 10 also includes a fuel injector 36, securely mounted in a central, component, or fuel injector bore 38 formed in cylinder head 20, for injecting fuel at very high pressure into combustion chamber 14 when piston 22 is approaching, at, or moving away from, the TDC position. In other configurations, central bore 38 may include a spark plug or other ignition device in place of fuel injector 36, which would then be positioned elsewhere in cylinder head 20. Injector 36 includes, at its inner end, an injector nozzle assembly 40. Injector 36 includes a plurality of injection orifices 42, formed in the lower end of nozzle assembly 40, for permitting high-pressure fuel to flow from a nozzle valve cavity of injector 36 into combustion chamber 14 at a very high pressure to induce thorough mixing of the fuel with the high temperature, compressed charge air within combustion chamber 14. It should be understood that injector 36 might be any type of injector capable of injecting high-pressure fuel through a plurality of injector orifices into combustion chamber 14 in the manner described hereinbelow. For example, injector 36 may be a closed nozzle injector or an open nozzle injector. Moreover, injector 36 may include a mechanically actuated plunger housed within the injector body for creating the high pressure during an advancement stroke of the plunger assembly. Alternatively, injector 36 may receive high-pressure fuel from an upstream high-pressure source such as a pump-line-nozzle system including one or more high-pressure pumps and/or a high-pressure accumulator and/or a fuel distributor. Injector 36 may include an electronically actuated injection control valve that supplies high-pressure fuel to the nozzle valve assembly to open injector nozzle assembly 40, or controls the draining of high-pressure fuel from the nozzle valve cavity to create a pressure imbalance on a nozzle valve element of injector nozzle assembly 40. The pressure imbalance thereby causes the nozzle valve element to open and close to form an injection event. For example, the nozzle valve element may be a conventional spring-biased closed nozzle valve element actuated by fuel pressure, such as disclosed in U.S. Pat. No. 5,326,034, the entire content of which is incorporated by reference. Injector 36 may be in the form of the injector disclosed in U.S. Pat. No. 5,819,704, the entire content of which is hereby incorporated by reference.
Referring to
Referring now to
As best seen in
Extending from bottom deck 164a is a plurality of intake passages 28a and a plurality of exhaust passages 32a. Each intake passage 28a opens in bottom deck 164a and extends away from bottom deck 164a, curving to extend between a first pair of bolt bosses 44a. Thus, each intake passage 28a forms an angle for the intake airflow, an angle that may be approximately 90 degrees. Intake passages 28a connect to an engine intake manifold (not shown). Exhaust passages 32a also open in bottom deck 164a, initially extending away from bottom deck 164a in a direction that may be parallel to intake passages 28a. Exhaust passages 32a may then curve to extend between another or second pair of bolt bosses 44a in a direction that is generally opposite from where intake passages 28a extend between the first pair of bolt bosses 44a. Each exhaust passage 32a forms an angle for the exhaust flow, an angle that may be approximately 90 degrees. Exhaust passages 32a connect to an engine exhaust manifold (not shown).
A wall or rib 52 extends longitudinally upward or away from an upper wall portion 84a of a wall portion 84 of each intake passage 28a. Wall or rib 52 connects to and extends upwardly along an interior boss portion 54 of bolt boss 44a to a boss portion or location 56 that is near a top surface 45a of bolt boss 44a. In an exemplary embodiment, rib 52 extends to a location on bolt boss 44a that is at least 50% of the distance from bottom deck 164a to top surface 45a. Preferably, rib 52 extends to a location on bolt boss 44a that is at least 75% of the distance from bottom deck 164a to top surface 45a. The connection of rib 52 to bolt boss 44a is at a first side or end of rib 52. Wall or rib 52 also extends to and connects to an interior boss portion 58 of a valve boss 48a at the base of each valve boss 48a. The connection of rib 52 to valve boss 48a is at a second end or side of rib 52. One valve boss 48a also extends from each wall portion 84 of each intake passage 28a. Rib 52 may extend upwardly along valve boss 48a, but to permit adequate cooling fluid flow through cylinder head 120a, rib 52 preferably extends to less than 50% of the distance from the base of valve boss 48a to the top of valve boss 48a. Each rib 52 may also extend longitudinally from a bottom deck portion 59 of bottom deck 164a in some locations, as may be best seen in
One wall or rib 52 also extends longitudinally upward from an upper wall portion 85a of wall portion 85 of each exhaust passage 32a. Each wall or rib 52 connects to and extends upwardly along interior boss portion 54 of one bolt boss 44a to boss portion or location 56 that is near top surface 45a of bolt boss 44a. The connection of rib 52 to bolt boss 44a is at a first side or end of rib 52. In an exemplary embodiment, rib 52 extends to a location on bolt boss 44a that is at least 50% of the distance from bottom deck 164a to top surface 45a. Preferably, rib 52 extends to a location on bolt boss 44a that is at least 75% of the distance from bottom deck 164a to top surface 45a. Wall or rib 52 also extends to and connects to interior boss portion 58 of a valve boss 48a at the base of each valve boss 48a. The connection of rib 52 to valve boss 48a is at a second end or side of rib 52. One valve boss 48a also extends from each wall portion 85 of each exhaust passage 32a. Rib 52 may extend upwardly along valve boss 48a, but to permit adequate cooling fluid flow through cylinder head 120a, rib 52 should extend to less than 50% of the distance from the base of valve boss 48a to the top of valve boss 48a. Each rib 52 may also extend longitudinally away from bottom deck portion 59 of bottom deck 164a in some locations, as may be best seen in
Each rib 52 terminates in an upper or top edge 53a. Upper or top edge 53a may appear to be generally flat or a straight line when viewed from a side of rib 52, or perpendicular to the longitudinal extent of rib 52 that extends from bottom deck 164a. However, upper or top edge 53a may also form a slight convex shape. It is less preferable for upper or top edge 53a to form a concave shape because such a shape is less capable of handling stresses transmitted from bottom deck 164a, walls 84 and walls 85 to bolt bosses 44a. Except when noted, the shape of the ribs in the subsequent embodiments should be similar to the shape of ribs 52.
A peak cylinder pressure capability (PCP) of a conventional cylinder head similar to cylinder head 20, which may be defined as the pressure exerted on a cylinder head by an associated combustion chamber, was measured to be 193 bar. The configuration of the first embodiment of the present disclosure achieves 240 bar peak cylinder pressure. The material of conventional cylinder head 20 and first embodiment cylinder head 120a that achieves the aforementioned PCP is gray iron. The dimensions that may be associated with cylinder head 120a are as follows: a bottom deck or fire deck 164a thickness of 17 millimeters; a mid deck 162 thickness of 5 millimeters; a top deck 160 thickness of 15 millimeters; a distance of the center of mid deck 162 longitudinally from the center of bottom deck 164a of 27.5 millimeters; a thickness of a side wall portion 172 of 13 millimeters; and a minimum thickness of a central bore wall 174a of 10 millimeters. The thickness of each rib 52 should be sufficient for casting purposes. For example, the thickness of ribs 52 may be in the range 3 millimeters to 10 millimeters, such as 5 millimeters thick. Ribs 52 may be thicker if needed, but should be configured to avoid interference with the function of upper coolant gallery 166. Ribs 52 should be limited to the minimum thickness necessary to withstand the design PCP, otherwise cylinder head 120a uses more material than necessary and becomes heavier than needed. All the aforementioned features that include a connection or joint should contain a radius at the connection. The joint radius should be as large as practicable. For example, a beneficial radius may be approximately 6 millimeters. Of course, depending on the space available, such connection or joint radii could be much larger.
The principal benefit of ribs 52 is that they permit removal of 75% of the material in the area of upper water jacket or coolant gallery 166 while retaining or even increasing the PCP of cylinder head 120a. This benefit is provided by limiting or reducing the material unrelated to the strength of cylinder head 120a, while adding material at the locations and in the configurations described hereinabove. The ability to remove material while increasing the PCP by appropriate placement of ribs 52 was an unexpected result. In the first exemplary embodiment of the present disclosure, the result of the addition of ribs 52 in conjunction with the dimensions provided above led to an increase in the structural efficiency of cylinder head 120a over a conventional cylinder head of 15%, where structural efficiency is defined as the ratio of stiffness to mass. As previously described, ribs 52 permit removal of material from cylinder head 120a while increasing the PCP of cylinder head 120a, thus leading to the improved structural efficiency. The structural stiffness of cylinder head 120a, which is defined as the capacity to resist deformation under applied load, was increased by 32% over a conventional cylinder head. Modifying the various dimensions provided hereinabove in combination with ribs 52 would lead to improvements in the PCP and the structural efficiency that are different from the example just provided.
A second exemplary embodiment cylinder head of the present disclosure, indicated generally at 120b, is shown in
Cylinder head 120b features a plurality of ribs 152 that extend longitudinally from a fire or bottom deck 164b at a bottom deck portion 78 to connect to a central portion 76 of a central bore wall 174b, forming an angle to fire deck 164b. Portion 78 is located on bottom deck 164b between a wall portion 88 of an intake passage 28b and a wall portion 89 of an exhaust passage 32b. A portion of ribs 152 may connect or attach to an upper wall portion 88a of wall portion 88, or an upper wall portion 89b of wall portion 89, or both, depending on the location of an edge of wall 88 where wall 88 originates from bottom deck 164b and the location of an edge of wall 89 where wall 89 originates from bottom deck 164b. Ribs 152 provide additional PCP capability when used with ribs 52. Ribs 152 may be used by themselves, though with less PCP capability than ribs 52.
A third exemplary embodiment cylinder head of the present disclosure, indicated generally at 120c, is shown in
Cylinder head 120c features a plurality of ribs 252 that extend longitudinally from an upper wall portion 86a of a wall portion 86 of an intake passage 28c or an upper wall portion 87b of a wall portion 87 of an exhaust passage 32c. Ribs 252 connect to and extend longitudinally upward along a central bore wall 174c at a first end of ribs 252, and connect to and extend longitudinally upward along a boss portion 80 of a valve boss 48c at a second end of ribs 252. Boss portion 80 is positioned on a side of valve boss 48c that faces central bore wall 174c. Each rib 252 extends to a point on central bore wall 174c that is as longitudinally as far from a bottom deck 164c as possible while maintaining adequate cooling fluid flow through cylinder head 120c. In an exemplary embodiment, each rib 252 extends to a point along central bore wall 174c at least 50% of the distance from bottom deck 164c to a top surface 175 of central bore wall 174c. Each rib 252 also extends to a point on valve boss 48c that is as longitudinally as far from bottom deck 164c as possible while maintaining adequate cooling fluid flow through cylinder head 120c. In an exemplary embodiment, each rib 252 extends to a point along valve boss 48c that is longitudinally less than the distance rib 252 extends along central bore wall 174c.
An upper edge 252a of rib 252 forms an angle to fire deck 164c, with the connection of upper edge 252a to central bore wall 174c longitudinally further from bottom deck 164c than is the connection of upper edge 252a to wall portion 80 of valve boss 48c. Thus, upper edge 252a extends longitudinally downward toward bottom deck 164c as upper edge 252a extends from central bore wall 174c to valve boss 48c. Ribs 252 provide additional PCP capability for cylinder head 120c when used in conjunction with ribs 52. Ribs 252 may also be used in conjunction with ribs 152. While ribs 252 may be used by themselves, the improvement in PCP is much less than the improvement in PCP provided by ribs 52 or ribs 152, and thus ribs 252 are more effective when used with one or more other ribs described in the other embodiments of this disclosure.
A fourth exemplary embodiment cylinder head of the present disclosure, indicated generally at 120d, is shown in
Cylinder head 120d features a plurality of ribs 352, each of which extends longitudinally upward from a bottom deck 164d and connects at a first end or side and a second end or side of ribs 352 to facing wall portions of a pair of bolt bosses 44d, connecting bolt bosses 44d to bottom deck 164d. A top edge 352a of each rib 352 connects to bolt boss 44d at a longitudinal location as far as possible from bottom deck 164d as possible while providing adequate cooling fluid flow through cylinder head 120d. Top edge 352a of each rib 352 extends at an angle from each bolt boss 44d at a location on each bolt boss 44d that may be more than 50% of the longitudinal distance from bottom deck 164d to a top surface 91 of each bolt boss 44d toward bottom deck 164d, forming a “V” shape when viewed in a direction that is perpendicular to rib 352.
One rib 352 extends longitudinally upward at least in part from one or more wall portions 92 of one or more intake passages 28d. Where this rib 352 connects to wall portions 92, rib 352 is blended or radiused into wall portion 92 of a respective intake passage 28d. A portion of rib 352 may extend into an intake passage 28d to provide additional structural capacity to rib 352. However, the amount that rib 352 extends into intake passages 28d cannot interfere with adequate intake airflow through intake passages 28d. One rib 352 extends longitudinally upward at least in part from one or more wall portions 93 of one or more exhaust passages 32d. Where this rib 352 connects to wall portions 93, rib 352 is blended or radiused into wall portion 93 of a respective exhaust passage 32d to provide additional structural capacity to rib 352. A portion of rib 352 may extend into an exhaust passage 32d to provide additional structural capacity to rib 352. However, the amount that rib 352 extends into exhaust passages 32d cannot interfere with adequate exhaust flow through exhaust passages 32d.
Ribs 352 provide improved sealing of cylinder head 120d with an engine body by increasing the rigidity of cylinder head 120d. The increased rigidity of cylinder head 120d improves the sealing effectiveness of a sealing mechanism located between cylinder head 120d and an associated engine body. Such sealing mechanism may include a head gasket located between cylinder head 120d and the associated engine body. Ribs 352 may also improve durability of an associated head gasket since flexing of the head gasket along the sealing joint is reduced by the presence of ribs 352. Ribs 352 may be used with one or more of the ribs of the previously described embodiments. By using ribs 352 in combination with one or more of the previously described embodiments, sealing of cylinder head 120d against an associated engine may be further improved.
A fifth exemplary embodiment cylinder head of the present disclosure, indicated generally at 120e, is shown in
Cylinder head 120e features ribs 452. A pair of ribs 452 extends longitudinally away or upwardly from a bottom deck 164e, from a wall portion 94 of an intake passage 28e, and/or from a wall portion 95 of an exhaust passage 32e, depending on the location of the pair of ribs 452. For example, one pair of ribs 452 may extend longitudinally away from bottom deck 164e and from an upper wall portion 94a of wall portion 94, connecting to a bolt boss 44e and extending to an upper interior portion 82 of bolt boss 44e. In another example, one pair of ribs 452 may extend longitudinally away from bottom deck 164e and from an upper wall portion 95b of wall portion 95, connecting to bolt boss 44e and extending to upper interior portion 82 of a bolt boss 44e. In an exemplary embodiment, rib 452 extends to a location on bolt boss 44e that is at least 50% of the distance from bottom deck 164e to top surface 91. Preferably, rib 452 extends to a location on bolt boss 44e that is at least 75% of the distance from bottom deck 164e to top surface 91. Each pair of ribs 452 forms a “V” shape when viewed from a direction that is generally perpendicular to the plane of bottom deck 164e. Each one of the pair of ribs 452 lies on either side of a plane 96 that extends perpendicularly to and through bottom deck 164e, through the center of a component or central bore 38e, and through the center of a bolt boss 44e. A plane 97 extending perpendicularly to bottom deck 164e through the center of two valve bosses 48e that does not intersect central bore 38e will extend through one rib 452 of two different rib pairs. The angle of the “V” may be within the range 20 degrees to 60 degrees, but is more preferably within the range 30 degrees to 50 degrees, and most preferably in the range 35 degrees to 45 degrees.
When ribs 452 intersect upper wall portion 94a of wall portion 94 of intake passages 28e and upper wall portion 95b of wall portion 95 of exhaust passages 32e, ribs 452 are blended or radiused into wall portions 94a of wall portions 94 of intake passages 28e and wall portions 95b of wall portions 95 of exhaust passages 32e. Ribs 452 may extend into intake passages 28e and exhaust passages 32e to increase the rigidity of cylinder head 120e. However, ribs 452 should not interfere with the function of intake passages 28e and exhaust passages 32e. The improvement in PCP from ribs 452 is comparable to the PCP improvement from ribs 52. As with the previous embodiments, ribs 452 may be used in conjunction with the previously described embodiments to improve the PCP of cylinder head 120e.
A sixth exemplary embodiment cylinder head of the present disclosure, indicated generally at 120f, is shown in
Cylinder head 120f features ribs from all the previously described embodiments, and the numbering of the ribs from the previously described embodiments is retained for simplicity and clarity, though use of all the ribs from the previous embodiment may entail minor modifications of the ribs of the previous embodiments to enable some ribs to be placed side-by-side. Use of all the exemplary embodiments provides the greatest possible PCP. However, use of all ribs may provide excessive restriction of the upper coolant gallery and the lower coolant gallery, which should be considered regardless which combination of previously described embodiments may be used.
While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications.
