Patent Application
20150361862
The present application relates generally to a cylinder block, an attached cylinder head, and cooling passages for providing effective cooling to all parts of the cylinder block and head.
Engine systems often comprise a cylinder block with an attached cylinder head that include a series of cylinders with surrounding material for attaching various components. Cylinder blocks and cylinder heads also include cooling systems that comprise a number of cooling passages that surround the cylinders. A coolant, such as water, oil, glycol, etc., may be pumped or otherwise sent through the cooling passages to remove heat from the cylinders and cylinder block and head via heat exchange. The cooling passages may include inlets and outlets such that coolant at a lower temperature is directed into the cylinder block and head while coolant at a higher temperature is exited from the cylinder block to a heat exchanger or other device. As such, the temperature of the cylinder block and cylinder head may be maintained within a desirable range during engine operation. In some systems, there may be fluidic communication between the cooling passages of the cylinder head and cylinder block. Various cooling systems exist for providing different amounts of cooling to different areas of the cylinder block.
In one approach to provide a cooling system to cool cylinders of an engine, shown by Lenz et al. in U.S. Pat. No. 8,555,825, cooling passages are provided in a cylinder head for receiving coolant from the cylinder block. In one embodiment, coolant is routed out of a cylinder block water jacket via a cooling passage of the cylinder head, along a bridge between two cylinders, and into another cooling passage of the cylinder head to provide cooling to portions proximate to intake and exhaust valves of the cylinders. In other words, coolant is pumped from the cylinder block to the cylinder head, then back into the cylinder block along the bridge in a cooling slot, and finally back into the cylinder head. The cooling slot provides the intermediate connection to allow coolant to flow from the cylinder block into the cylinder head. The fluidic communication between the cylinder head and cylinder block allows coolant located in the cylinder block to flow into the cylinder head proximate to the cylinder and intake/exhaust valves.
However, the inventors herein have identified potential issues with the approach of U.S. Pat. No. 8,555,825. First, while the cooling passages proposed by Lenz et al. allow fluidic communication between the cylinder block and cylinder head, only a single coolant may be routed through the cooling passages. The system does not allow a different degree of cooling to be provided by a different coolant in a particular area of the cylinder block/head assembly. For example, if one portion of the cylinders is desired to be maintained within a certain temperature range while another portion of the cylinders is desired to be maintained within a different temperature range, then two coolants may be directed throughout the assembly. Furthermore, coolant from the coolant jacket surrounding the cylinders may have a high temperature before entering the cooling slot in the bridges as well as the areas proximate to the intake/exhaust valves, thereby decreasing the efficiency of heat removal. Since coolant passing into the cylinder head may be heated by the cylinders first, then a lower amount of heat than desired may be removed from the bridge and cylinder head.
Thus in one example, the above issues may be at least partially addressed by a method, comprising: cooling a cylinder head with a first coolant; cooling a cylinder block with a second coolant, the second coolant a different liquid than the first coolant; and cooling a plurality of bore bridges with the first coolant while maintaining separation between the passages containing the first and second coolants, the plurality of bore bridges in between adjacent cylinders of the cylinder block. In this way, the cylinder head and cylinder block are cooled with separately-maintained cooling systems while a portion of the first coolant (e.g., water) of the cylinder head may aid in cooling certain portions of the cylinder block, in particular the bore bridges.
When a vehicle is first turned on, it may be desirable to rapidly increase the temperature of the engine in order to improve fuel economy. While a water-cooled cylinder block may most effectively remove heat from the engine, a more-than-desired amount of heat may be removed. Alternatively, an oil-cooled cylinder block may remove heat less rapidly than the water-cooled cylinder block, but localized high-temperature regions may exist that adversely affect engine performance. The regions may include the portions in between cylinders known as bore bridges. In some examples, the oil-cooled cylinder block with water-cooled bore bridges may allow the engine to rapidly warm-up while providing sufficient cooling to the bore bridges via the water passages with water from the cylinder head.
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.
The following detailed description provides information regarding an oil-cooled cylinder block with a water-cooled cylinder head and their associated components. A simplified schematic diagram of a vehicle system is shown in
Turbocharger 50 may include a compressor 52, arranged between intake passage 42 and intake manifold 44. Compressor 52 may be at least partially powered by exhaust turbine 54, arranged between exhaust manifold 48 and exhaust passage 35. Compressor 52 may be coupled to exhaust turbine 54 via shaft 56. Compressor 52 may also be at least partially powered by an electric motor 58. In the depicted example, electric motor 58 is shown coupled to shaft 56. However, other suitable configurations of the electric motor may also be possible. In one example, the electric motor 58 may be operated with stored electrical energy from a system battery (not shown) when the battery state of charge is above a charge threshold. By using electric motor 58 to operate turbocharger 50, for example at engine start, an electric boost (e-boost) may be provided to the intake air charge. In this way, the electric motor may provide a motor-assist to operate the boosting device. As such, once the engine has run for a sufficient amount of time (for example, a threshold time), the exhaust gas generated in the exhaust manifold may start to drive exhaust turbine 54. Consequently, the motor-assist of the electric motor may be decreased. That is, during turbocharger operation, the motor-assist provided by the electric motor 58 may be adjusted responsive to the operation of the exhaust turbine.
Engine exhaust 25 may be coupled to exhaust after-treatment system 22 along exhaust passage 35. Exhaust after-treatment system 22 may include one or more emission control devices 70, which may be mounted in a close-coupled position in the exhaust passage 35. One or more emission control devices may include a three-way catalyst, lean NOx filter, SCR catalyst, etc. The catalysts may enable toxic combustion by-products generated in the exhaust, such as NOx species, unburned hydrocarbons, carbon monoxide, etc., to be catalytically converted to less-toxic products before expulsion to the atmosphere. However, the catalytic efficiency of the catalyst may be largely affected temperature by the temperature of the exhaust gas. For example, the reduction of NOx species may require higher temperatures than the oxidation of carbon monoxide. Unwanted side reactions may also occur at lower temperatures, such as the production of ammonia and N2O species, which may adversely affect the efficiency of exhaust treatment, and degrade the quality of exhaust emissions. Thus, catalytic treatment of exhaust may be delayed until the catalyst(s) have attained a light-off temperature. Additionally, to improve the efficiency of exhaust after-treatment, it may be desirable to expedite the attainment of the catalyst light-off temperature. An engine controller may be configured to inject blow-through air flow into the exhaust after-treatment system, through the cylinders, during an engine cold start, to thereby reduce the light-off time. The air flow, performed during a positive intake to exhaust valve overlap period, may enable fresh blow-through air to be mixed with combusted exhaust gas and generate an exhaust gas mixture in the exhaust manifold. The blow-through air flow may provide additional oxygen for the catalyst's oxidizing reaction. Furthermore, the air flow may pre-clean the extra-rich exhaust from the cold engine, and help bring the catalytic converter quickly up to an operating temperature.
Exhaust after-treatment system 22 may also include hydrocarbon retaining devices, particulate matter retaining devices, and other suitable exhaust after-treatment devices (not shown). It will be appreciated that other components may be included in the engine such as a variety of valves and sensors.
The vehicle system 6 may further include a control system 14. Control system 14 is shown receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 81 (various examples of which are described herein). As one example, sensors 16 may include exhaust gas sensor 126 (located in exhaust manifold 48), temperature sensor 128, and pressure sensor 129 (located downstream of emission control device 70). Other sensors such as pressure, temperature, air/fuel ratio, and composition sensors may be coupled to various locations in the vehicle system 6, as discussed in more detail herein. As another example, the actuators may include fuel injectors 45 (described later), a variety of valves, electric motor 58, and throttle 62. The control system 14 may include a controller 12. The controller may receive input data from the various sensors, process the input data, and trigger the actuators in response to the processed input data, based on instruction or code programmed therein, corresponding to one or more routines. In particular, controller 12 may be a microcomputer, including microprocessor unit, input/output ports, an electronic storage medium for executable programs and calibration values such as a read only memory chip, random access memory, keep alive memory, and a data bus. The storage medium read-only memory can be programmed with computer readable data representing instructions executable by the processor for performing the control methods for different components of
In some embodiments, each cylinder of engine 10 may be configured with one or more fuel injectors for providing fuel thereto. As a non-limiting example, cylinders 30 are shown including fuel injectors 45 coupled directly to cylinders 30. Fuel injectors 45 may inject fuel directly therein in proportion to a pulse width of a signal received from controller 12 via an electronic driver. In this manner, fuel injectors 45 provide what is known as direct injection (hereafter referred to as “DI”) of fuel into combustion cylinder 30. While
It will be appreciated that in an alternate embodiment, injectors 45 may be port injectors providing fuel into a series of intake ports upstream of cylinders 30 in intake 23. It will also be appreciated that cylinders 30 may receive fuel from a plurality of injectors, such as a plurality of port injectors, a plurality of direct injectors, or a combination thereof.
Engine 10, containing cylinders 30 and other components, may be formed from several large pieces. For example, a top portion of the engine 10 containing camshafts, intake/exhaust ports, and fuel injection components may be contained in a cylinder head that is attached to a separate engine block. The engine block may contain the geometry that defines the shape of cylinders 30 as well as various passages for the cooling system for removing heat from cylinders 30 during engine operation.
With modern vehicles, there is a constant demand for improving fuel economy, which may be achieved by modifying various systems of the vehicle. One way to improve fuel economy is to quickly increase the temperature of the engine after the vehicle is turned on after a period of being off. In other words, by decreasing the time to warm-up the engine, fuel economy may be improved. Fast engine warm-up may help reduce friction and emissions that are commonly higher at engine start-up compared to a fully-warm engine. In this context, engine warm-up may include increasing the temperature of the engine and associated components, including but not limited to, the cylinder block, cylinder head, pistons, cylinders, and intake/exhaust valves.
One way to decrease the warm-up time of the engine is to use oil as the coolant in the cooling passages/jacket of the cylinder block. Due to the properties of oil, an oil-cooled cylinder block may increase in temperature at a higher rate than a water-cooled cylinder block. In other words, oil transfers heat at a lower rate than other coolants such as water or glycol. While the engine may heat up faster with an oil coolant, high local temperatures may occur in the areas in between adjacent cylinders. The higher local temperatures may be high enough to adversely affect engine performance and/or increase the risk of damage to the cylinder block, cylinder head, and other components. As such, an oil-cooled cylinder with a redesign is needed to cool the areas between adjacent cylinders. The areas in between adjacent cylinders are also known as bore bridges, or the top of the bores (cylinders) where common walls are shared between cylinders.
Both cylinder blocks 190 and 200 include bore bridges 204 and 205, respectively, which are defined by the upper portion of material located in between adjacent cylinders. In other words, the bore bridges 204 and 205 include material forming the cylinder walls between cylinders of the cylinder blocks 190 and 200, respectively. As seen in
While the other regions of cylinder block 200 remain at lower temperatures similar to the equivalent regions of cylinder block 190, the temperature of cylinder block 200 rapidly increases in the regions surrounding bore bridge 205 and in the bore bridge 205 itself. As a result, bore bridge 205 may exhibit temperatures well in the 200° C. range while bore bridge 204 exhibits temperatures below 200° C. The elevated temperature of bore bridge 205 may lead to abnormal cylinder degradation and adversely affect engine performance. While cylinder block 200 with the oil coolant may heat-up more rapidly during engine warm-up compared to cylinder block 190, the bore bridge 205 may exhibit temperatures outside the range of desired temperatures for optimal engine performance and safety. Without adequate cooling to bore bridge 205, water-cooled cylinder block 190 may be more desirable than oil-cooled cylinder block 200.
The inventors herein have recognized that an oil-cooler cylinder block is feasible while providing adequate cooling to the bore bridges. With a water-cooled cylinder head coupled to an oil-cooled cylinder block, a cross-drilling can be drilled in the bore bridges to allow water from the cylinder head to flow through the bore bridges of the cylinder head while maintaining separation between the cooling passages of the cylinder head and cylinder block. With this configuration, the rapid warm-up properties of the oil-cooled cylinder block may be achieved while controlling the temperature of the bore bridges within a desired range with water from the cylinder head. The embodiments of an oil-cooled cylinder block, water-cooled cylinder head, bore bridge, and coolant passages described hereafter may be modified while still providing oil and water cooling to the cylinder block, wherein the oil and water do not mix.
The bore bridge 205 contains a cross-drilled passage (not visible) with an inlet 315 and an outlet 316, which are symmetrical about a section line 4-4. Water, or other coolant such as glycol different from the oil coolant of cylinder block 200, may generally flow into inlet 315, through the cross-drilled passage, and exit from outlet 316. In this way, the oil passages 321 and 322 do not connect to the cylinder head and the water cooling passage of the cylinder head traverses the bore bridge 205 via the cross-drilled passage. The shape of the cross-drilled passage is explained in further detail in
As seen in
It is noted that while only two cylinders 310 and 311 are shown in
The geometry of cylinder blocks may generally fall into one of two categories: open and closed deck designs. Open deck cylinder blocks maintain a clearance between the material of the cylinder bores and outer walls of the cylinder block throughout the majority of the circumferences of the cylinders. In open deck designs, multiple clearances or gaps may be present throughout the cylinder block, where the gaps may be used as cooling passages or jackets that aid in removing heat generated during the combustion process. In many open deck designs, the only material connecting adjacent cylinders and the outer walls of the cylinder block is located in the bore bridges, such as bridge 205 of
Apex 583 has a different shape than apex 383 of
Furthermore, from the side view of
A method for cooling the systems shown in
In this way, by providing the cross-drilled passages in the bore bridges of either the open or closed deck cylinder blocks, the temperature ranges (i.e., local temperatures) of bore bridges in between adjacent cylinders may be controlled while allowing the rest of the cylinders to quickly heat during engine warm-up. Furthermore, the addition of the cross-drilled passages may not require readjusting bore spacing, that is, the thickness of the bore bridges in between each cylinder. As such, major redesign of existing cylinder blocks may be unnecessary, thereby reducing costs associated with the aforementioned cross-drilled passages. By allowing the engine to warm up more rapidly compared to water-cooled cylinder blocks, friction and emissions may be reduced with the proposed oil-cooled cylinder block to increase fuel economy and engine efficiency. Additionally, with the separately-cooled cylinder head and cylinder block, the cooling systems associated with the first and second coolants may be controlled independently or in conjunction with each other.
Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system.
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, 1-4, 1-6, 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.
