Patent Grant
7540264
The field of the disclosure relates to initialization of electric valves coupled to cylinder valves of an internal combustion engine, and more particularly for a dual coil valve actuator.
Electric valve actuators can be used to actuate cylinder valves, such as intake and/or exhaust valves of an internal combustion engine. When using electric valve actuators for such systems, it may be beneficial to initialize the valves to preselected positions to reduce battery loading.
One approach for initializing valves is described in U.S. Pat. No. 6,202,608. As illustrated in
However, the inventors herein have recognized a disadvantage with such an approach. In particular, because all of the valves are initialized before cranking begins, total engine starting time can be lengthened. Thus, the delay between a requested start by the driver and the actual engine start can be increased, thereby leading to degraded customer satisfaction. Further, in the case illustrated in
The above disadvantages can be overcome by a method for initializing valves of an engine having a starting apparatus, the method comprising:
moving at least a first valve away from a neutral position of the first valve before the engine is rotated by the starting apparatus; and
moving at least a second valve away from a neutral position of the second valve during engine rotation by the starting apparatus.
In this way, engine starting time may be decreased since, in one example, less than all of the engine cylinder valves may be initialized before engine rotation begins, at least under some conditions. Further, by leaving at least one valve in a neutral, or mid position, (which can be a partially opened position in some examples) until after rotation has begun, energy needed to rotate the engine can be decreased since the piston does not need to be moved against as much vacuum or compressed air as that created by closed valves.
Note that there are various ways to move a valve away from a neutral position, which may include pulling the valve to an open or closed position, or oscillating the valve away from a neutral position. The neutral position may be a partially open position, a closed position, or an open position, for example. Note also that there are various approaches for rotating an engine, such as via a starter motor or integrated starter/alternator assembly. Further note that moving valves during rotation of the engine may include moving after rotation of the engine has begin, or simultaneously moving a valve at the beginning of engine rotation, for example.
In another aspect of the present disclosure, a system for an engine comprises at least one electromechanically actuated valve coupled to the engine; at least mechanically driven valve coupled to the engine; and a controller for moving at least said electromechanically actuated valve away from a neutral position of said electromechanically actuated valve during engine rotation. In this way, it may be possible to reduce power consumption during starting since at least one valve is mechanically driven.
Various example methods for initializing the valves in an Electro-Magnetic Valve Actuation (EVA) system are described. Among other things, the example methods relate to one or more of the following factors that may be relevant during the start-up phase of an EVA system:
1) initializing the valves into their desired position for an engine start, which may be completed in a selected period of time,
2) consideration of the power supply capability, which may limit the number of valves that can be initialized simultaneously or non-simultaneously (e.g., battery state of charge, battery voltage, battery temperature, or combinations thereof, or others),
3) coordination of the valve initialization with the engine start-up process, e.g., starting rotation of the engine after certain valves are initialized, reducing the starter loading by starting engine rotation with valves in the open position, etc., and
4) EVA actuator driver circuitry specific requirements that may constrain the number and order in which the valves can be initialized. As an example of the fourth factor, when a split supply dual coil half bridge converter (described below herein) is used, the power supply midpoint voltage may be regulated within a specified range in order to provide desired operation of the actuators. Other forms of actuator driver circuitry may place similar constraints on the method used to initialize the valve positions.
The following description illustrates various example systems and approaches for engine control and/or valve initialization in an EVA engine.
Referring now specifically to
Internal combustion engine 10 comprises a plurality of cylinders, one cylinder of which is shown in
As described more fully below with regard to
Intake manifold 44 communicates with throttle body 64 via throttle plate 66. Throttle plate 66 may be controlled by electric motor 67, which receives a signal from ETC driver 69. ETC driver 69 may receive control signal from controller 12. In an alternative embodiment, no throttle is utilized and airflow may be controlled using valves 52 and 54. Further, when throttle 66 is included, it can be used to reduce airflow if valves 52 or 54 become degraded, or to create vacuum to draw in recycled exhaust gas (EGR), or fuel vapors from a fuel vapor storage system having a valve controlling the amount of fuel vapors.
Intake manifold 44 may also have fuel injector 68 coupled thereto for delivering fuel in proportion to the pulse width of signal (fpw) from controller 12. Fuel may be delivered to fuel injector 68 by a conventional fuel system (not shown) including a fuel tank, fuel pump, and fuel rail (not shown). Engine 10 may further include conventional distributorless ignition system 88 to provide ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. In the embodiment described herein, controller 12 may be a conventional microcomputer including: microprocessor unit 102, input/output ports 104, electronic memory chip 106, which is an electronically programmable memory in this particular example, random access memory 108, and a data bus.
Controller 12 may receive various signals from sensors coupled to engine 10, in addition to those signals previously discussed, including: measurements of inducted mass air flow (MAF) from mass air flow sensor 110 coupled to throttle body 64; engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling jacket 114; a measurement of manifold pressure from MAP sensor 129, a measurement of throttle position (TP) from throttle position sensor 117 coupled to throttle plate 66; a measurement of transmission shaft torque, or engine shaft torque from torque sensor 121, a measurement of turbine speed (Wt) from turbine speed sensor 119, and a profile ignition pickup signal (PIP) from Hall effect sensor 118 coupled to crankshaft 13 indicating an engine speed (N). Alternatively, turbine speed may be determined from vehicle speed and gear ratio.
Continuing with
In an alternative embodiment, where an electronically controlled throttle is not used, an air bypass valve (not shown) can be installed to allow a controlled amount of air to bypass throttle plate 62. In this alternative embodiment, the air bypass valve (not shown) receives a control signal (not shown) from controller 12.
Also, in yet another alternative embodiment, intake valve 52 can be controlled via actuator 210, and exhaust valve 54 actuated by an overhead cam, or a pushrod activated cam. Further, the exhaust cam can have a hydraulic actuator to vary cam timing, known as variable cam timing. Such a configuration may still provide many benefits of electromechanically driven intake valves and variable exhaust valve timing, but may reduce energy draw during starting of the engine since a reduced number of valves need to be initialized away from a mid position.
In still another alternative embodiment, only some of the intake valves can be electrically actuated, and other intake valves (and exhaust valves) can be cam actuated.
Note that the engine EVA system is not limited to a dual coil actuator, but rather it can be used with other types of actuators. For example, the actuators of
Referring to
Switch-type position sensors 228, 230, and 232 are provided and installed so that they switch when the armature 220 crosses the sensor location. It is anticipated that switch-type position sensors can be easily manufactured based on optical technology (e.g., LEDs and photo elements) and when combined with appropriate asynchronous circuitry they would yield a signal with the rising edge when the armature crosses the sensor location. It is furthermore anticipated that these sensors would result in cost reduction as compared to continuous position sensors, and would be more reliable.
Controller 234 (which can be combined into controller 12, or act as a separate controller) is operatively connected to the position sensors 228, 230, and 232, and to the upper and lower coils 216 and 218 in order to control actuation and landing of the valve 212.
The first position sensor 228 is located around the middle position between the coils 216 and 218, the second sensor 230 is located close to the lower coil 218, and the third sensor 232 is located close to the upper coil 216.
As described above, engine 10, in one example, has an electro-mechanical valve actuation (EVA) with the potential to improve torque over a broad range of engine speeds and substantially improve fuel efficiency. The increased fuel efficiency benefits are achieved by eliminating the throttle, and its associated pumping losses, (or operating with the throttle substantially open, in at least some operating conditions) and by controlling the engine operating mode and/or displacement, through the direct control of the valve timing, duration, and/or lift, on an event-by-event basis, or combinations thereof.
In one example, controller 234 includes any of the example power converters described below.
While the above method can be used to control valve position, an alternative approach can be used that includes continuous position sensor feedback for potentially more accurate control of valve position. This can be use to improve overall position control, as well as valve landing, to possibly reduce noise and vibration.
As illustrated above, the electromechanically actuated valves in the engine may remain in the half open position when the actuators are de-energized. Therefore, prior to engine combustion operation, each valve may go through an initialization cycle. During an initialization period, the actuators can be pulsed with current, in a prescribed manner, in order to establish the valves in the fully closed or fully open position. Following this initialization, the valves can be sequentially actuated according to the desired valve timing (and firing order) by the pair of electromagnets, one for pulling the valve open (lower) and the other for pulling the valve closed (upper).
The magnetic properties of each electromagnet are such that only a single electromagnet (upper or lower) need be energized at any time. Since the upper electromagnets may hold the valves closed for the majority of each engine cycle, they may be operated for a much higher percentage of time than that of the lower electromagnets.
In one example, during power-up in an EVA engine, all (or a portion) of the electromechanically valves can be held in the half open position by a pair of valve springs, as shown by
Initially the EM solenoids can bring the valve from a center (rest) position to either the fully open or fully closed positions. This may be accomplished for each valve, i.e., up to thirty-two valves in a 4 electromechanically actuated valve per cylinder 8-cylinder engine, to move the valves into positions that allow a start-up of the engine.
In order to initialize electromechanically actuated valves, various high level control routines can be used. Further, the control routines included herein can be used with various engine configurations, such as those described above and/or below. As will be appreciated by one of ordinary skill in the art, the specific routine described below in the flowchart(s) 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 steps or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing may not necessarily be required to achieve the features and advantages of the example embodiments of the invention described herein, but may be provided for ease of illustration and description. Although not explicitly illustrated, one of ordinary skill in the art will also recognize that one or more of the illustrated steps or functions may be repeatedly performed depending on the particular strategy being used. Further, the flowchart(s) below graphically represents code to be programmed into the computer readable storage medium in controller 12, or 230, or combinations thereof.
In one example, a method to robustly initialize an EVA engine valvetrain is described. In one approach, the electromechanically actuated valves may be brought from the center, de-energized position to an initialized open or closed position without unnecessarily lengthening the time to start the engine, or without unnecessarily depleting battery storage. To do this, under some conditions, it may be desirable to initialize multiple valves simultaneously in order to minimize the overall time required. However, in other conditions, it may be desirable to initialize multiple valves sequentially. Thus, the number and order in which the valves are initialized may be constrained by the capability of the vehicle power supply, the engine startup process, and the capability of the actuator driver circuitry. Because these constraints vary throughout the usage and life of the vehicle/engine, it may also be desirable to have a process that robustly takes these factors into consideration to robustly initialize the valves in the EVA system.
As noted above, the initialization of a single valve can be done by either directly pulling-in the valve or creating an oscillation that assists in pulling-in the valve, for example. The direct pull-in method works by energizing one of the two coils in the actuator, either the open or close coil, and using the force produced by that coil to directly pull the valve to either the open or closed position in a single stroke. Because of the large force needed to overcome the actuator/valve spring forces, the direct pull-in method may require a relatively large instantaneous power, which may reduce the number of valves that can be simultaneously initialized. The oscillating pull-in method works by alternatively energizing the two coils in the actuator to excite the spring-mass oscillator's natural resonance, which may reduce the amount of power required to initialize the valve position but may increases the time required. Either approach, or still other approaches, can be used in the approaches described herein.
Examples of EVA driver circuits are shown in
While
Referring now to
Continuing with
Referring now to
Note that while the examples herein use a dual coil actuator, the converter topology is not limited to dual coil actuators. Rather, it can be used with any system that utilizes multiple actuator coils. Thus, it should be noted that adjacent pairs of converter switches are not necessarily confined to be paired with a single actuators' coils (i.e. each coil of a given actuator may be driven by switches from different legs of the converter).
In the above example, a split-power supply, which provides a return path for the actuator coil currents, is used. In one example, the split supply could be realized using a pair of batteries. However, this may unnecessarily add cost and weight to the vehicle. Therefore, in another example, a split capacitor bank 530 and 532 can be used to transform a single battery into a dual voltage source, as shown in
Note that a capacitor is an example of an energy storage device, and various types of devices can be used to act as a capacitor or energy storage device. Note also that a diode is an example of a unidirectional current device that allows current only to flow in substantially one direction. Various other devices could also be used to provide a diode type function.
In the example dual coil half-bridge design, each actuator coil is connected to the split voltage supply through what can be thought of as a DC/DC converter. Those connected using a high-side switch form a buck DC/DC converter from the supply voltage to the split voltage (mid-point voltage), and those connected using a low-side switch form a boost DC/DC converter from the split voltage to the supply voltage.
The coils are actuated via their respective switches, and the capacitors alternate charge and discharge during the operation of the coils.
Referring now specifically to
In one embodiment, actuator coils 512 and 514 represent the two coils of an intake valve actuator in a cylinder of the engine, and actuator coils 516 and 518 represent an exhaust valve actuator of the same cylinder of the engine. In another embodiment, actuator coils 512 and 514 represent the two coils of an intake valve actuator in a cylinder of the engine, and actuator coils 516 and 518 represent an intake valve actuator in another (different) cylinder of the engine. Further, in another embodiment, actuator coils 512 and 514 represent the two coils of an exhaust valve actuator in a cylinder of the engine, and actuator coils 516 and 518 represent an exhaust valve actuator in another (different) cylinder of the engine. As indicated and discussed below, certain configuration can provide a synergistic result in terms of maintaining a balance of charge in the capacitors.
Continuing with
An alternative arrangement would have the four actuator coils be the upper and lower coils for two intake or two exhaust actuators on the same cylinder. In this case, coils 512 and 514 would be the two upper coils of the two actuators and 516 and 518 would be the two lower coils (or vice versa).
Example operation of the converter of
Operation of the coil 514 proceeds concurrently with the operation described above for coil 512 and is as follows. When a decrease in the current flowing in coil 514 is desired, switch 522 is closed (positive current flow defined as flowing from the point connecting coil 514 to switch 522 into the point connecting coil 514 to capacitors 530 and 532). At this time, a negative voltage is applied across coil 514 through switch 522 causing the current level in coil 514 to decrease. After some time, the charge on capacitor 530 has increased and the charge on capacitor 532 has decreased, resulting in a reduced voltage across capacitor 532 (since the pair of capacitors are sized such that they have enough capacity to withstand normal excursions in actuator current with only small changes in their terminal voltage). Then, when an increase in the current level in coil 514 is desired, switch 522 is opened. The current flowing through coil 514 forces diode 536 to conduct (turn-on), which applies a positive voltage across coil 514, causing the current level in coil 514 to increase. After some time, the charge on capacitor 530 has decreased and the charge on capacitor 532 has increased, resulting in a increased voltage across capacitor 532. When another decrease in current is desired, the process is repeated.
The operation of the circuit for coils 516 and 518 and for any additional coils in the system may follow a similar procedure to that described above for coils 512 and 514. It should also be noted that the above described operations, alternatively increase and decrease the 6 volt balance across the capacitors 530 and 532, on average this alternating action will act to balance the voltages on the two capacitors.
The above is an example description of how the converter may be operated. The example converter of
Note that while only four actuator coils are shown in
In
However, the split-capacitor voltage source arrangement may result in different charges being stored in the capacitors, due to the unequal current applied to different coils (e.g., opening versus closing, intake versus exhaust, or combinations thereof, for example). In other words, the balance of charge can be affected by the configuration of these coils in the dual coil half-bridge converter, and therefore the configuration can cause various types of results. Thus, in one example, system configuration is selected to maintain the balance of the charge on each capacitor. However, this system has to contend with the high number of coils in the engine, and the wide range of current that each is conducting.
One method of connecting the coils that assists in advantageously maintaining the required balance is to connect an equal number of similar loads (i.e. upper/lower (high-side/low side) coils, exhaust/intake valves) in either the buck DC/DC converter configuration or the boost DC/DC converter configuration. When the total load through the buck converter connected coils matches that through the boost converter connected coils, a natural balance of the split voltage supply can occur.
However, the inventors herein have recognized that various alternative modes of operation may also affect the balance of charge, such as during starting of the engine. Thus, by proper selection of which valves to actuate and which to hold closed/open on each cylinder, it may be possible to obtain improved charge balance in the converter. Further, proper selection for each cycle may also aid in maintaining the balance of the split voltage supply. Also, by appropriately selecting the connection of the coils in the converter, improved charge balance may be achieved. Thus, in addition to selecting which valve to operate, coil connection in the converter may be used to improve balancing. I.e., obtaining charge balance through selection of which valve to operate limits the operating modes available, whereas connecting the coils in a preferred fashion increases the operating modes available.
The concept described above for configuring the actuator coils to the split voltage supply can also be applied to other engine configures (I4, V6, etc.) and to differing number of intake and exhaust valves.
Still another alternative embodiment can be accomplished by changing the wiring connections between the battery and the capacitors, as shown in
Referring now specifically to
Continuing with
An alternative arrangement would have the four actuator coils be the upper and lower coils for two intake or two exhaust actuators on the same cylinder. In this case, coils 612 and 614 would be the two upper coils of the two actuators and 616 and 618 would be the two lower coils (or vice versa).
As discussed above,
While connecting an equal number of similar loads (i.e. upper/lower coils, exhaust/intake valves) in either the buck or the boost converter configuration assists in maintaining the required capacitor charge balance, actuator loads may not be exactly equal. In other words, when the total load through the buck converter connected coils matches that through the boost converter connected coils, a natural balance of the split voltage supply will occur. However, since the actuator loads may not be exactly equal, an additional method of maintaining the charge balance (and providing the desired voltage on each of the capacitors), may be needed. Therefore, in one alternative embodiment, a midpoint voltage regulator (MVR) may be used as discussed in more detail below.
Note that the desired voltage across each of the capacitors can be determined by the ratio of the individual stored charge and the capacitance value (V=q/C). This ratio may be chosen to be unity, i.e. equal voltage across each capacitor, or some other value depending on the requirements of the system.
Referring now to
Again note that while the examples herein use a dual coil actuator, the converter topology is not limited to dual coil actuators. Rather, it can be used with any system that utilizes multiple actuator coils. Thus, it should be noted that adjacent pairs of converter switches are not necessarily confined to be paired with a single actuators' coils (i.e. each coil of a given actuator may be driven by switches from different legs of the converter), although they may be.
In one example, a split-power supply, which provides a return path for the actuator coil currents, is used. In one example, the split supply could be realized using a pair of batteries. However, this may unnecessarily add cost and weight to the vehicle. Therefore, in another example, a split capacitor bank can be used to transform a single battery into a dual voltage source, as shown in
In the example bi-directional dual coil half-bridge design, each actuator coil may be connected to the split voltage supply through what can be thought of as a DC/DC converter. Operation using a high-side switch forms a buck DC/DC converter from the supply voltage to the split voltage (mid-point voltage), and operation using a low-side switch forms a boost DC/DC converter from the split voltage to the supply voltage.
The coils are actuated and/or deactivated via coordination of their respective switch pair, and the capacitors alternately charge and discharge during the operation of the coils.
Referring now specifically to
In one embodiment, actuators A1 and A2 represent the two coils of an intake valve in a cylinder of the engine, and actuators A3 and A4 represent an exhaust valve of the same cylinder of the engine. In another embodiment, actuators A1 and A2 represent the two coils of an intake valve in a cylinder of the engine, and actuators A3 and A4 represent an intake valve in another (different) cylinder, or the same cylinder, of the engine. Further, in another embodiment, actuators A1 and A2 represent the two coils of an exhaust valve in a cylinder of the engine, and actuators A3 and A4 represent an exhaust valve in another (different) cylinder, or the same cylinder, of the engine. As indicated and discussed below, certain configuration can provide a synergistic result in terms of maintaining a balance of charge in the capacitors.
Continuing with
One arrangement would have the four actuator coils be the upper and lower coils for two intake or two exhaust actuators on the same cylinder. In this case, coils A1 and A2 would be the two upper coils of the two actuators and A3 and A4 would be the two lower coils (or vice versa).
An alternative embodiment can be accomplished by changing the wiring connections between the battery and the capacitors, as shown in
Referring now specifically to
Note that while only four actuator coils are shown in
Thus,
Description of valve initialization during engine start-up, or during engine re-starting (e.g., in a Hybrid-electric vehicle) is described.
Specifically, in any of the above examples, the order of valve initialization during engine start-up can be selected to provide improved charge balance on the converter, if desired. In other words, which of the valves are initialized (before/during rotation), and in what order, can be selected and varied to improve charge balancing, and/or to take into account different operating conditions.
Also, the order of valve initialization can be adjusted based on vehicle and power supply conditions. For example, if the power supply has a higher capacity in some conditions, more valves can be initialized before the engine is rotated by the starting apparatus. Alternatively, if the power supply has a higher capacity in some conditions, less valves can be initialized before the engine is rotated by the starting apparatus.
Referring now to
In one example, the regulation can be accomplished by exploiting the inherent buck and boost converter actions, described above. Specifically, by commanding additional buck action when the MP voltage gets too low (and/or additional boost action when the MP voltage gets too high) a mechanism for providing the regulation function can be implemented.
One method that can be used to implement a midpoint voltage regulator is to add an additional buck/boost DC/DC converter in parallel with the dual coil half-bridge converter, whose purpose is to provide a regulation function, although it can be used for other functionality, if desired. While this approach can achieve the desired result, it may unnecessarily waste energy in its operation. Therefore, in an effort to improve overall operation, an alternative embodiment uses another form of a midpoint voltage regulator. Specifically, this alternative midpoint voltage regulator uses the actuator coils (the dual coil half-bridge converter) to implement the desired regulation. This is achieved, as described below, without compromising the primary current control function of the converter.
Note that in many applications, midpoint voltage regulation using the actuator coils may not be possible because each of the loads (actuators) on the converter would be required to follow a current command that cannot be varied for any ancillary purposes. However, in the application for engine cylinder valve actuation, actuator current regulation may be required to follow a specific command under some conditions (such as specific transient periods of operation). But, under other conditions, actuator current can vary within a larger range from the desired value. Recognition of this allows synergistically exploitation of the circuit structure to enable midpoint voltage regulation without unnecessarily wasting energy. In other words, this may provide the opportunity to interleave midpoint voltage regulation within the normal actuator current control function.
The flowchart in
In step 810 the routine determines example power supply capabilities based on current operating conditions, such as ambient temperature, battery state of charge, engine temperature, battery life, or combinations thereof. Then, in step 812, the routine determines the number of electromechanically actuated valves that can be simultaneously actuated, due to the status of the vehicle power supply system, and valve actuator operating conditions, before the engine is rotated. This determination may be made based on, but not limited to, voltage, temperature and battery state of charge, valve actuator impedance, or combinations thereof. The relationship between the power supply status and the number of valves that can be initialized may be a calibratable quantity and may be implemented in the algorithm as a look-up table, a fixed mathematical relationship, etc.
Note that in step 812, the number of electromechanically actuated valves that can be simultaneously actuated is determined for the case where valves are simultaneously actuated before the engine rotates, such as illustrated in
Specifying the initialization of zero valves before engine rotation may further reduce starting time. If driver requests reduced starting time by requesting engine rotation, without substantial delay (0-5 seconds), after a key or power on condition, starting time may be reduced by initializing valves during engine cranking. Since valve timing is based on engine position, and since engine position is usually determined during cranking, the period between the beginning of engine cranking and where engine position is determined, may be used to initialize valves and further reduce delay time before cranking.
Once the number of valves is determined in step 812, the routine selects the particular valves to initialize based on the engine strategy, for example, in step 814. In one example, the valves selected to be initialized are selected to initialize intake valves first, or initialize exhaust valves first, or initialize intake and exhaust valves simultaneously, or initialize the valves on particular cylinders before rotating engine, or combinations thereof.
In one particular example where a 4 cylinder engine is used, two cylinders are selected for initialization having pistons in different locations. In this way, the first cylinder to carry out combustion can be selected from these two cylinders to enable improved starting time, since depending on where the engine stopped, one of these two cylinders will be available for a first combustion earlier than the other due to the different piston positions. This is described in more detail below with regard to
Continuing with
As noted in
Continuing with
From step 820, the routine continues to step 822 to initialize the remaining valves, and then proceed to step 824 to determine whether all electromechanical valves are in the desired position. If not, the routine returns to step 822. If so, the routine continues to step 826 to start the engine, e.g., start the engine by injecting fuel and igniting it in a combustion stroke of the engine.
In one example where valves of some cylinders are initialized before rotation, and the valves of other cylinders are initialized after rotation, the initialization of the remaining valves in step 822 is performed to set the stroke of the remaining cylinders to the proper stroke to provide the desired firing order of the engine.
This starting approach can be illustrated in various example plots showing starting sequences that may be used. For example, referring to
Note that the timing diagram of
In the example illustrate in
In general terms, in the example illustrate in
Subsequently, this process is repeated for each of the cylinders in the firing order.
The remainder of
Referring now to
Next, in step 912, the routine selects whether simultaneous or sequential initialization of cylinder valves is selected. Note, as discussed above herein, either initialization approach can be used, or combinations thereof can be used. Next, in step 914, the routine initiates rotation of the engine.
Next, in step 916, the routine determines whether piston position/direction has been identified from the engine crank sensor, for example. If not, the routine continues to monitor crank position to identify the engine/piston position and/or direction. Once piston position has been identified, the routine continues to step 918. In step 918, the routine selects a cylinder to carry out first combustion from the cylinders identified as being available in step 910. Thus, for the example described above where cylinders 3 and 4 are selected as the available cylinders, the routine determines in step 918, based on piston position and/or direction of piston movement, which of cylinders 3 and 4 will be the cylinder first able to carry out combustion. In one example, this selection may be based on which cylinder has a piston moving downward with sufficient piston travel remaining to be able to induct sufficient air to carry out a first combustion event.
From step 918, the routine continues to step 920 to initialize the remaining cylinder valves and start firing the engine. These can be performed together or the valves can be first initialized, and then engine firing began.
An example timing diagram to illustrate operation according to the approach of
As illustrated in
After engine cranking is commenced, then piston position/direction is identified at the location indicated by the arrow 930. At this point, the routine has identified that cylinder 3 may be the first cylinder able to perform a sufficient intake stroke to induct sufficient air to carry out first combustion event. Therefore, the routine sets the stroke of each of cylinders 3 and 4 (which also sets the stroke of the remaining cylinders), and adjusts the valves to the desired stroke timing. Specifically, the routine sequentially sets each of the intake and exhaust valves of cylinders 3 and 4 to the desired positions to create intake, compression, power, exhaust strokes with the appropriate fuel injection and spark timing to prolong a first combustion event in cylinder 3 followed by combustion in cylinder 4.
During the setting of the strokes of cylinders 3 and 4, along with moving the valves to desired positions for cylinders 3 and 4, the routine also initializes the valves sequentially in cylinders 1 and 2. Note that in this way, the initialization of at least some valves in cylinders 1 and/or 2 may occur after the engine has been fired first in cylinder 3. In this way, it may be possible to reduce the initial initialization time before engine cranking. Further, at the same time, it may be possible to reduce power consumption by the battery during cranking since at least some valves can be initialized after the engine has performed at least some combustion, thereby reducing the loading of the starting apparatus.
Note that the timing diagram of
Still further variations are illustrated in the timing diagrams of
Referring back to
As illustrated in
Once one of cylinders 3 and 4 is identified to carry out a first combustion event, the remaining valve timings may be set to provide the desired firing order, 1-3-4-2 in this example, although others can be used if desired.
In this example, the valve initialization of cylinders 1 and 2 may be delayed until after engine rotation begins, and potentially after firing of one of cylinders 3 and 4. Specifically, once the timing of cylinder 3 is set, the initialization of cylinders 1 and 2 can be determined. Again, closed intake valve injection may be used. Further, the initialization of the exhaust valve (or intake valves) to a closed or open position in cylinders 1 and/or 2 can also be varied (based on operating conditions such as temperature) or delayed to reduce current usage during engine cranking. As shown in
As indicated above, still further variations may be used. For example,
While
In the example illustrated in
Still another alternative embodiment is illustrated in the timing diagram of
While the above examples illustrate operation according to the embodiment where two valves per cylinder of an I-4 engine are used, they can be applied to other engine types such as, for example: V-6 engines, I-6 engines, V-8 engines, V-10 engines, V-12 engines and various others. Likewise, they may be applied to engines having 1 electromechanical valve per cylinder, 2 electromechanical valves per cylinder, 3 electromechanical valves per cylinder, and/or 4 electromechanical valves per cylinder, or combination thereof.
The flowchart in
The flowchart shown in
In general terms, the midpoint voltage regulator uses a proportional integral controller to adjust the midpoint voltage to a desired value.
Referring now specifically to
Once the number of valves is determined in step 1112, the routine determines the number high side (HS) and low side (LS) driven coils that can be initialized while provided a desired midpoint voltage range. Then, the routine selects the particular valves to initialize based on the engine strategy, for example, in step 1114, and the determinations of steps 1110-1113.
Continuing with
From step 1120, the routine continues to step 1122 to initialize the remaining valves, and then proceed to step 1124 to determine whether all electromechanical valves are in the desired position. If not, the routine returns to step 1122. If so, the routine continues to step 1126 to start the engine, e.g., start the engine by injecting fuel and igniting it in a combustion stroke of the engine.
The flowchart in
Referring now specifically to
Once the number of valves is determined in step 1202, the routine determines whether the boosted supply voltage is greater than the target value in step 1204. If not, the routine continues to step 1206 to determine the number of LS coils that can be energized, and then continues to step 1214. Otherwise, if the answer to step 1204 is yes, the routine continues to step 1208 to determine the number of HS and LS driven coils that can be energized.
Then, the routine selects the particular valves to initialize based on the engine strategy, for example, in step 1214, and the information from steps 1200-1208.
Continuing with
From step 1220, the routine continues to step 1222 to initialize the remaining valves, and then proceed to step 1224 to determine whether all electromechanical valves are in the desired position. If not, the routine returns to step 1222. If so, the routine continues to step 1226 to start the engine, e.g., start the engine by injecting fuel and igniting it in a combustion stroke of the engine.
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 converter technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. Also, the approach described above is not specifically limited to a dual coil valve actuator, or to any of the specific converter configurations described. Rather, it could be applied to other forms of actuators, including ones that have only a single coil per valve actuator, and to actuators powered by different converter topologies.
The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein.
The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. 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 subcombinations 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.
The present application is a continuation of U.S. patent application Ser. No. 10/873,713, filed Jun. 21, 2004 now U.S. Pat. No. 7,021,255, and entitled “Initialization of Electromechanical Valve Actuator in an Internal Combustion Engine,” the entire contents of which are incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3884207 | Kuehn, III | May 1975 | A |
| 4794890 | Richeson, Jr. | Jan 1989 | A |
| 5124598 | Kawamura | Jun 1992 | A |
| 5596956 | Ogawa et al. | Jan 1997 | A |
| 5669341 | Ushirono et al. | Sep 1997 | A |
| 5775276 | Yanai et al. | Jul 1998 | A |
| 5804962 | Kather et al. | Sep 1998 | A |
| 5940262 | Archer | Aug 1999 | A |
| 6186100 | Sawada | Feb 2001 | B1 |
| 6201681 | Torii et al. | Mar 2001 | B1 |
| 6202608 | Yamaki et al. | Mar 2001 | B1 |
| 6363895 | Butzman et al. | Apr 2002 | B1 |
| 6374783 | Toriumi | Apr 2002 | B1 |
| 6463896 | Fujiwara et al. | Oct 2002 | B1 |
| 6626146 | Yanai et al. | Sep 2003 | B1 |
| 6631067 | Newton et al. | Oct 2003 | B2 |
| 7021255 | Degner et al. | Apr 2006 | B2 |
| 7036469 | Degner et al. | May 2006 | B2 |
| 7051687 | Shimizu et al. | May 2006 | B2 |
| 7054737 | Degner et al. | May 2006 | B2 |
| 20020104494 | Ozawa et al. | Aug 2002 | A1 |
| 20050207086 | Degner et al. | Sep 2005 | A1 |
| Number | Date | Country |
|---|---|---|
| 19701471 | Jul 1998 | DE |
| 1010867 | Jul 2004 | EP |
| 2000073834 | Mar 2000 | JP |
| 2000073834 | Mar 2000 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20060150933 A1 | Jul 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10873713 | Jun 2004 | US |
| Child | 11372649 | US |
