Patent Application
20120312257
Exhaust manifolds for internal combustion engines may be exposed to high thermal loads. Exhaust manifolds that are integrated into cylinder heads (IEM cylinder heads) may experience particularly high thermal loading due to the heat transfer characteristics of the integrated design. For example, IEM cylinder heads may channel exhaust to a collector and a single exhaust port, which experiences a high thermal load during operation of the vehicle.
Thermal loading of an IEM and neighboring components can be reduced by incorporating coolant jackets into the cylinder head. The coolant jackets with, a coolant core formed therein, can reduce the thermal stresses on the cylinder head caused by heat generated during engine operation. For example, a cylinder head having an integrated exhaust manifold is disclosed in U.S. Pat. No. 7,367,294. Upper and lower coolant jackets encompass a major portion of the cylinder head to remove heat from the cylinder head via heat exchange with a circulated liquid coolant.
However, the inventors herein have recognized issues with the above described approach. For example, during some conditions, steam may accumulate in portions of the coolant passages, such as in portions of the coolant chamber positioned vertically at a top of the passages in the IEM and proximate to the exhaust port. Accumulation of steam and/or other gases causes the liquid coolant to lose contact with at least a top wall of the coolant jacket. Under such conditions, the temperature of cylinder head can increase in a region of the cylinder head proximal the accumulated steam, particularly in a region proximal to the exhaust collector and the exhaust port. As a result, the cylinder head and/or other cylinder components may thermally degrade. Further, exhaust gases may be insufficiently cooled and downstream engine or vehicle components, such as a turbocharger and/or an emission control system, may also thermally degrade.
As such, various example systems and approaches to address the above issues are described herein. In one example, an engine cooling system comprises a cylinder head including an integrated exhaust manifold that directs exhaust gases to an exhaust port; a coolant passage surrounding the exhaust manifold and having a coolant jacket above the exhaust port; and a degas port positioned along the top side of the coolant jacket, the degas port fluidically coupled to the coolant passage at an inlet of the degas port. The degas port may be further coupled to a degas bottle at an outlet of the degas port. The degas bottle may permit pressure relief via a pressure release valve and return of liquid coolant to a coolant passage of a radiator. Furthermore, a temperature sensor may be included in the coolant jacket at a position near exhaust collector and/or the exhaust port to communicate a temperature signal to a controller of the vehicle. If the temperature signal is greater than a predetermined threshold, an overheating indication may be provided and/or corrective action may be taken by the engine control system.
In this way, the cooling system may provide improved engine overheating protection. For example, steam accumulated at the top of the coolant chamber can be vented from the coolant chamber to the degas bottle. As a result, the liquid coolant may maintain contact with the coolant jacket wall, and continue heat exchange in order to decrease thermal stress on the cylinder head by generating a convective coolant circuit. Thus, the degas port along the top side of the coolant jacket may decrease the likelihood of thermal degradation of the cylinder head and cool exhaust gas to decrease the likelihood of thermal degradation on downstream components, such as the turbocharger, the emission control system, etc. Further, the temperature sensor may provide an improved indication of over-temperature conditions in the exhaust system. Thus, performance and life of the engine, turbocharger, and emission control system can be improved.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
An engine cylinder head with an integrated exhaust manifold (IEM cylinder head) is described herein. The integrated exhaust manifold directs exhaust from a plurality of inlet ports to a common exhaust collector and exhaust outlet port. The IEM cylinder head includes a coolant core formed from a plurality of coolant passages in communication with a coolant inlet and a coolant outlet. The coolant passages may include a coolant jacket that surrounds (at least partially) the exhaust manifold and in particular the outlet port. The IEM cylinder head cooling system may be configured to flow coolant through passages in the cylinder head via pressure generated by a coolant pump. In this way, cooling via heat exchange may be provided to the IEM cylinder head via the coolant jacket. The exhaust collector and the exhaust port may normally experience higher temperatures due to the flow characteristics within the integrated exhaust manifold. Moreover, heat exchange between the coolant jacket wall and the engine exhaust gases may cool engine exhaust and provide thermal protection to downstream components, such a turbocharger and/or an emission control system, etc. In a case where the coolant pump is damaged or the cooling system loses at least some of the liquid coolant, the IEM cylinder head may increase in temperature and steam may accumulate in a top portion of the coolant core. Liquid coolant may lose contact with the coolant jacket wall at a location where steam is accumulated, and heat exchange may be reduced. Thus, locally high temperatures may occur, thus thermally degrading the IEM cylinder head. Further, exhaust gas temperatures may increase, thus degrading downstream components of the exhaust system.
To at least partially address such conditions, a degas port may be included in an upper wall of the IEM cylinder head, such as at a dome in the vertical-most position of the coolant passages in the IEM cylinder head. The degas port may be fluidically coupled to the coolant core through the upper wall of the IEM cylinder head and the coolant jacket. The degas port may permit release of accumulated steam from the coolant chamber and generate a convective current, and thus liquid coolant may maintain contact with the upper wall of the coolant jacket. In this way, thermal stress on the IEM cylinder head, the exhaust port, and over-temperature conditions of downstream components may be reduced.
Further, at a confluence location proximal to the exhaust collector and the exhaust port, the IEM cylinder head may include a temperature sensor in communication with a controller of the vehicle. The controller may identify conditions where the sensed temperature is greater than a threshold in order to provide such indications to the operator, and/or to adjust engine operating conditions to reduce exhaust gas temperature of combustion gasses. Thus, the above described features may decrease the likelihood of thermal degradation of the IEM cylinder head, the exhaust collector, the exhaust port, the cylinder block, and/or downstream components, thereby increasing the life of engine components.
The example IEM cylinder head described herein includes a vent, such as a degas port, in the upper coolant jacket, and may further include a temperature sensor in the upper coolant jacket.
Referring to
Intake manifold 44 is also shown intermediate of intake valve 52 and air intake zip tube 42. Fuel is delivered to fuel injector 66 by a fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). The engine 10 of
Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Universal Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 126.
Converter 70 can include multiple catalyst bricks, in one example. In another example, multiple emission control devices, each with multiple bricks, can be used. Converter 70 can be a three-way type catalyst in one example.
Controller 12 is shown in
In some embodiments, the engine may be coupled to an electric motor/battery system in a hybrid vehicle. The hybrid vehicle may have a parallel configuration, series configuration, or variation or combinations thereof.
Cooling system 200 includes coolant circuit 250 traveling through one or more cylinder block coolant passage(s) 251 in a cylinder block 252. Water or another suitable coolant may be used as the working liquid in the coolant circuit. The cylinder block may include a portion of one or more combustion chambers. It will be appreciated that the coolant circuit may travel adjacent to the portions of the combustion chambers. In this way, excess heat generated during engine operation may be transferred to the coolant circuit. An IEM cylinder head 253 may be coupled to the cylinder block to form a cylinder assembly. When assembled, the cylinder assembly may include a plurality of combustion chambers. Combustion chamber 30 shown in
The cylinder head cooling system further includes an upper coolant jacket 254 and a lower coolant jacket 256. It will be appreciated that the upper and lower coolant jackets are integrated into the cylinder head. The upper coolant jacket includes a plurality of coolant passages 258 comprising an upper coolant core. Likewise, the lower coolant jacket includes a plurality of coolant passages 260 comprising a lower coolant core. As shown, the upper coolant jacket includes a coolant inlet 262 and the lower coolant jacket includes a coolant inlet 264. However, it will be appreciated that the upper and/or lower coolant jackets may include a plurality of inlets in other embodiments. For example, the upper coolant jacket may include a single inlet and the lower coolant jacket may include a plurality of inlets. It will be appreciated that the inlets of the upper and lower coolant jackets may be coupled to a common coolant passages in the cylinder block in some embodiments. In this way, the upper and lower coolant jackets receive coolant via their respective inlets from a common source included in an engine block of an engine. However, in other embodiments the inlets of the upper and lower coolant jackets may be coupled to separate coolant passages in the cylinder block.
A first set of crossover coolant passages 266 may fluidly couple the upper coolant jacket 254 to the lower coolant jacket 256. Similarly, a second set of crossover coolant passages 268 may fluidly couple the upper coolant jacket to the lower coolant jacket.
Each crossover coolant passage included in the first set of crossover coolant passages may include a restriction 270. Likewise, each crossover coolant passage included in the second set of crossover coolant passages may include a restriction 271. Various characteristics (e.g., size, shape, etc.) of the restrictions may be tuned during construction of cylinder head 253. Therefore, the restrictions 270 included in the first set of crossover coolant passages may be different in size, shape, etc., than the restrictions 271 included in the second set of crossover coolant passages. In this way, the cylinder head may be tuned for a variety of engines, thereby increasing the cylinder head's applicability. Although two crossover coolant passages are depicted in both the first and second sets of crossover coolant passages, the number of crossover coolant passages included in the first set and second sets of crossover coolant passages may be altered in other embodiments.
The crossover coolant passages allow coolant to travel between the coolant jackets at various points between the inlets and the outlets of both the upper and lower coolant jackets. In this way, the coolant may travel in a complex flow pattern where coolant moves between the upper and lower jackets, in the middle of the jacket and at various other locations within the jacket. The mixed flow pattern reduces the temperature variability within the cylinder head during engine operation as well as increases the amount of heat energy that may be removed from the cylinder head, thereby improving engine performance. The exhaust manifold 48 is disposed between the upper and lower coolant jackets, 254 and 256, respectively. As such, walls of the exhaust manifold may be cooled while transporting heated engine exhaust, subsequently at least partially cooling the engine exhaust.
A coolant pump 284 may also be included in the coolant circuit. A thermostat 286 may be positioned at the outlet 276 of the upper coolant jacket. A thermostat 288 may also be positioned at the inlet of the one or more coolant passage(s) 251 of the cylinder block 252. Additional thermostats may be positioned at other locations within the coolant circuit in other embodiments, such as at the inlet or outlet of the one or more coolant passage(s) in the radiator, the inlet of the upper coolant jacket, etc. The thermostats may be used to regulate the amount of fluid flowing through the coolant circuit based on the temperature. In some examples, the thermostats may be controlled via controller 12. However in other examples, the thermostats may be passively operated.
It will be appreciated that controller 12 may regulate the amount of head pressure provided by coolant pump 284 to adjust the flow-rate of the coolant through the circuit and therefore the amount of heat removed from the engine. Furthermore, in some examples, controller 12 may be configured to dynamically adjust the amount of coolant flow through the upper coolant jacket via thermostat 286. Specifically, the flow-rate of the coolant through the upper coolant jacket may be decreased when the engine temperature is below a threshold value. In this way, the duration of engine warm-up during a cold start may be decreased, thereby increasing combustion efficiency and decreasing emissions.
Cooling of the exhaust manifold and engine exhaust via the coolant circuit and coolant jackets may protect the exhaust manifold and downstream engine components from thermal degradation, such as warping due to temperature gradients and/or degradation due to over-temperature conditions. In one particular example, liquid coolant is circulated via the coolant pump. In this way, coolant may be circulated around the exhaust manifold, enabling heat to be removed from the exhaust manifold. Therefore, thermal stresses on the cylinder head exhaust manifold, as well as neighboring components, may be reduced, thereby increasing component longevity. The radiator enables heat to be transferred from the coolant circuit to the surrounding air. In this way, heat may be removed from the coolant circuit.
However, problems may arise in the cooling system. In one example, if the coolant pump degrades and/or if loss of liquid coolant occurs, steam may accumulate at a top-most portion of the coolant core, forming a gas pocket against an upper wall of the coolant jacket. In this example, the liquid coolant may lose contact with the upper coolant jacket at the location of the gas pocket, and thus heat exchange and cooling of the coolant jacket may be reduced in this location. In one specific example, the gas pocket may form in the coolant core at a top-most location (e.g., vertically highest location of the core) that is proximal to an exhaust outlet or exhaust port. As heated engine exhaust converges at this location, the exhaust port may be subjected to high heat during selected operating conditions of the vehicle. As described above, under normal operating conditions, heat exchange with the liquid coolant through the upper coolant jacket wall relieves the high temperatures and prevents damage to engine components. If the gas pocket is present at this location, high temperatures may occur due to reduced heat transfer, and thus thermal degradation may occur.
In order to at least partially reduce such degradation, the cooling system 200 includes a degas port 290 in the upper coolant jacket 254. Degas port 290 is located in a top surface of upper coolant jacket 254 in a region that is adjacent a vertically top-most portion of the upper jacket, and that is in fluid communication with the coolant chamber. An outlet of the degas port is coupled to a degas line 294, which is further coupled to a degas bottle 292. The degas bottle may include a pressure relief valve, which opens to relieve pressure when a pressure in the degas bottle 292 is greater than a threshold. In one example, the pressure relief valve may passively open when the pressure of the degas bottle is greater than 16 psi. In an alternate embodiment, the degas bottle may include a pressure sensor in communication with the controller, and the degas valve may be operated by the controller. Degas bottle 292 is further coupled to coolant passage 280 of the radiator 282, such that liquid reductant may be returned to coolant circuit 250. In alternate embodiments, the degas bottle may return liquid reductant at a different location of coolant circuit 250, such as the water pump or cylinder block. Further, the upper coolant jacket 254 may also include a temperature sensor 296.
Thus, in a condition where the coolant circuit becomes overheated and steam accumulates at a top portion of the upper coolant jacket, the degas port may direct the steam to the degas bottle, while liquid coolant remains in the coolant chamber and a convective current is generated. As such, heat exchange between the coolant and the coolant jacket wall, and heat exchange between the coolant jacket wall and the exhaust gas may continue, even if the coolant system degrades due to coolant loss or reduced coolant flow. In one specific embodiment, the degas port is located in a top wall of the cylinder head and an upper wall of the upper coolant jacket at a location which is proximal to a common exhaust collector and exhaust port. The coolant passage degas port is discussed in greater detail herein with regard to
As shown, IEM cylinder head 253 includes four perimeter walls. The walls include a first and a second side wall, 302 and 304 respectively. The four perimeter walls may further include a front end wall 306 and a rear end wall 308. A bottom wall 312 may be configured to couple to the cylinder head (not shown) thereby forming the engine combustion chambers, as previously discussed. A top wall 316 of the cylinder head further includes the degas port 290 including a valve configured to remove gas from the upper coolant jacket. More detailed views of the degas port are shown in
Cylinder head 253 includes exhaust port 320 to which a plurality of exhaust runners (not shown) are coupled. The exhaust runners may be coupled to the exhaust valves of each combustion chamber (not shown). In this way, the exhaust manifold and exhaust runners may be integrated into the cylinder head casting. The integrated exhaust runners have a number of benefits, such as reducing the number of parts within the engine thereby reducing cost throughout the engine's development cycle. Furthermore, inventory and assembly cost may also be reduced when an integrated exhaust manifold is utilized.
The cylinder head further includes exhaust manifold flange 273 surrounding the exhaust port 320. The flange includes bolt bosses 310 or other suitable attachment apparatuses configured to attach to a downstream exhaust component, such as an exhaust conduit or an inlet of a turbine included in a turbocharger. In this way, the turbocharger (not shown) may be mounted directly to the cylinder head reducing losses within the engine. The turbocharger may include an exhaust driven turbine coupled to a compressor via a drive shaft. The compressor may be configured to increase the pressure in the intake manifold.
The degas port may decrease the amount of gas (e.g., air and/or water vapor) in both the upper and lower coolant jacket, thereby allowing liquid coolant to be drawn to the coolant jacket walls and generating a current of liquid coolant flowing through the coolant circuit. The venting of gas may allow for the liquid coolant to maintain contact with the coolant jacket walls and provide cooling to the coolant jacket walls via heat exchange. Moreover, the coolant walls may cool hot exhaust gas passing through the exhaust port 320, and at least partially reduce degradation to downstream components, such as a turbocharger. Thus, the operating efficiency of the upper and lower coolant jackets may be increased in a condition where steam may otherwise accumulate in the coolant core.
As shown in
In the present embodiment, the degas port 290 is generally disposed vertically in the top wall 316. More specifically, the degas port 290 is angled outward from a center of the cylinder head at an angle X relative to the lateral axis of the integrated cylinder head 253. In one specific example, the angle X is 60 degrees. In alternate embodiments the degas port may be angled inward or may be parallel to a vertical axis of the cylinder head.
As shown, vertically aligned protrusions 820 included in both the upper and lower core may define the first set of crossover coolant passages 266. It will be appreciated that the crossover coolant passages may be vertically orientated relative to piston motion. The laterally aligned extensions 822 in both the upper and lower core may define the second set of crossover coolant passages 268. It will be appreciated that horizontally aligned extension 824 may define outlet 276 of the upper coolant jacket including restriction 277.
The upper and lower coolant jackets define a plurality of coolant passages, as previously discussed. Furthermore, the exhaust port 320 defines an opening to the exhaust manifold including a plurality of exhaust runners (not shown) fluidly coupled to the exhaust port. Thus, engine exhaust from the runners travels through the exhaust port during operation of the engine. As such, a temperature of the coolant core and the coolant jacket may increase at a region 750, which is proximate to the exhaust port and above the exhaust port. Thus, the region 750 may be a “hot zone” of the cylinder head. Further, as the region 750 is at a top of the coolant core 600 gases, such as air and/or steam, may accumulate at this region of the coolant core, particularly if the coolant pump is damaged and/or coolant loss occurs. As depicted in
In addition to the degas port 290, the cylinder head may include the temperature sensor 296 in the region 750. The temperature sensor is depicted in
The temperature sensor 296 is disposed within a vertical wall 1030 of the cylinder head 253. Vertical wall 1030 extends between passages of the upper core 610, and thus the temperature sensor 296 is encompassed by the upper core 610. For example, the temperature sensor is encompassed by the upper core because sides of the vertical wall wherein the temperature sensor is disposed are in contact with liquid coolant within the passages of the upper core. In an alternate example, the temperature sensor may be encompassed by the coolant core by being disposed within the coolant core and being in direct contact with liquid coolant. A conical tip end 1118 is proximate to an upper wall of the exhaust collector 630 and the region 750 of the coolant core 600. The conical tip end 1118 is a distance G from the top wall of the third exhaust runner passage 706. In one example, the distance G is 4.5 mm. The temperature sensor may provide a temperature measurement of the cylinder head within the region 750, at a location proximal to the exhaust face. As depicted in
The above described example cylinder head includes an integrated exhaust manifold. During operation of a vehicle including the cylinder head, the cylinder head may experience higher temperatures due to the flow characteristics within the integrated exhaust manifold. The cylinder head cooling system is configured to flow coolant through passages in the cylinder head to cool an IEM cylinder head. A degas port is disposed vertically in a top wall of the cylinder head, and is angled outward from a center of the cylinder head. The degas port is in fluid communication with an upper coolant core at a top most region of the upper coolant core. The degas port may allow release of accumulated steam from the coolant core, thus allowing liquid coolant to maintain contact with an upper coolant jacket wall. In this way, thermal stresses on the cylinder head walls, the exhaust port, and components downstream of the integrated exhaust manifold may be reduced. Further, the cylinder head may include a temperature sensor within a wall of the coolant jacket that is proximal to the exhaust port and encompassed by the passages of the upper coolant core. In a condition where the temperature in the region near the exhaust port is greater than a threshold, a warning signal may be sent to a driver to stop operation of the vehicle. Thus, the above described features may decrease the likelihood of thermal degradation of the exhaust collector, the exhaust port, the cylinder block, or neighboring components, such as a turbocharger, thereby increasing the components longevity.
It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.
The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.
