This invention relates to charge motion control valve (CMCV) actuators for regulating the positions of valves within intake manifold ports and control circuits therefor.
In 1970, Congress passed the Clean Air Act and established the Environmental Protection Agency (EPA) which initiated a series of graduated emission standards and requirements for maintenance of vehicles over extended periods of time. In the beginning there were few standards, however, in 1988, the Society of Automotive Engineers (SAE) developed a set of diagnostic test signals, and the EPA adapted most of the SAE standards for On-Board Diagnostic programs and recommendations (OBD). Currently, the second generation of these diagnostic standards (OBD-II) has been adopted by the EPA and, as such, internal combustion engine vehicles must now meet the federally mandated OBD-II standards for the life of the vehicle.
A main focus of the EPA in regard to internal combustion engines is on the emissions of the engines. To meet the current federally mandated emission standards prescribed by OBD-II, an internal combustion engine requires management of air flow through an intake manifold. In addition, regulatory requirements mandate that the components used to ensure compliance of the emission standards be continuously monitored over the life of the vehicle. This is in an effort to ensure that the emissions performance over the useful life of the vehicle is not degraded due to a component failure. Generally, actuators used to control the air flow through an intake manifold (herein referred to as CMCV actuators) have been constructed as two position actuators, having a fully open position and a fully closed position. In addition, the actuators generally do not provide position feedback capability to indicate which position the actuator is in. The two position actuators are limited in their ability to regulate the air flow through the intake manifold, and thus, restrict the ability of the engine to operate at its a maximum performance level, and further, limit the ability of the engine to meet emissions, and fuel economy goals.
The OBD-II regulations require that the presence and functionality of emission systems components be monitored. Generally, the monitoring function may be performed using one or more external sensors connected to the vehicle engine controller. This approach adds to the complexity of the emission system assembly, for example by adding additional components and wire connections. In addition, the added external components increase the amount of communication and analysis burden on the engine controller. Though the current OBD-II emission control system requirements come at an increased cost, the manufacturer has little option but to take on these expenses, as a result of having to meet the federally mandated standards.
The present invention provides a valve actuator method and apparatus for a charge motion control valve or other intake manifold valve. In accordance with one aspect of the invention, the valve actuator comprises a motor, output shaft, control circuit, and sensor. The output shaft is coupled to the motor and is adjustable to different positions by the motor. The control circuit has an input for receiving actuator commands and has an output connected to the motor to control operation of the motor. The sensor is connected to the control circuit and provides the control circuit with data indicative of the position of the output shaft. The control circuit operates the motor in response to the actuator commands to move the output shaft to a commanded position. The control circuit receives feedback signals from the sensor relating to the position of the output shaft. Preferably, the control circuit provides output data relating to the position of the output shaft. The control circuit can also use feedback signals to provide closed loop control of the position of the output shaft.
In accordance with another aspect of the invention, there is provided a valve actuator comprising a motor having a drive shaft, a set of driven components operably connected to the drive shaft, an output shaft driven to various positions by the motor via the driven components, a control circuit having an input for receiving actuator commands and having an output connected to the motor to control operation of the motor, and a stop member located adjacent one of the driven components such that the stop member engages that driven component at a predetermined position and prevents further rotation of that driven component past the predetermined position.
In accordance with yet another aspect of the invention, there is provided a method of operating an actuator for a charge motion control valve of the type having a park position representing a desired end of travel of the valve and having a stop member that stops movement of the valve at a stop position located beyond the park position, the actuator has a motor with a drive shaft connected to an output shaft via a set of gears, the output shaft being rotationally adjustable by the motor to a number of different positions within a normal range of operation including a first target position that corresponds to the park position of the valve. The method includes the steps of (1) energizing the motor to rotate the output shaft in one direction past the first target position to a second target position that is located beyond the stop position and outside of the normal range of operation, (2) outputting position data indicative of the position of the output shaft, and thereafter, (3) energizing the motor to rotate the output shaft in the opposite direction to return the output shaft to a selected position within the normal range of operation.
As illustrated in
In general, CMCV actuator 10 is a single, self contained module that includes a control circuit 18 which operates a motor 20 connected to an output shaft 22 via a gear set 24, all of which are mounted in a housing 26. The output shaft 22 extends out of housing 26 for operable communication with the intake manifold 12 to regulate the airflow through individual ports (not shown) within the intake manifold 12. As will be explained in further detail below, ECU 16 delivers actuator commands to control circuit 18 which responds to these command signals by energizing the motor 20 to rotate the output shaft 22 to the commanded position. A sensor 28, located adjacent a member driven by the gear set 24, and shown here as a carrier 30, detects the instantaneous position of the carrier 30 and, thus, the position of the output shaft 22 and the associated components therewith. The position information from this sensor 28 is fed back to the control circuit 18 which uses this feedback data to provide closed loop control of the angular orientation of the output shaft 22. Control circuit 18 is further operable to return feedback data to the ECU 16 indicating the actual, sensed position of the shaft 22 and its associated components.
As shown in
The base 32 has a lower wall 38 with a side wall 40 extending generally laterally and upwardly therefrom. The side wall 40 terminates at an outer perimeter defining a lateral flange 42 extending from the side wall 40 constructed for mating engagement with a flange 44 of the cover 34. Desirably, the flange 42 of the base 32 has a peripheral groove 46 (
As shown in
The gear set 24 comprises a drive gear 72, represented here as a worm gear coupled to driven shaft 64 and a driven gear 74, represented here as a segment gear supported for rotation by the output shaft 22. It should be understood that the gear set 24 may be configured differently by using a variety of differently sized or type gears and having differing numbers of gear teeth in order to meet the specific application requirements, such as load constraints, drive motion, and packaging constraints, for example.
As shown in
The segment gear 74 is rotatably received on the output shaft 22 for relative rotation therewith. The segment gear 74 has teeth 82 arranged for meshed engagement with teeth on the worm gear 72. The gear teeth 82 span approximately 120 degrees, although gear 74 is generally driven about 85 degrees in use. To facilitate operable communication between the segment gear 74 and the carrier 30, as discussed hereafter, desirably the segment gear 74 has a tab 84 (
As best shown in
As best shown in
As shown in
Control circuit 18 is a microprocessor based control circuit that continuously monitors ECU 16 for commands to rotate the output shaft 22 to a particular angular position. When receiving commands, the control circuit 18 preferably uses a debounce algorithm to insure that a valid position command has been sent by the ECU 16 before activating the motor 20 to initiate movement. Suitable debouncing algorithms are known to those skilled in the art.
To move the output shaft 22, control circuit 18 sends a signal to energize the motor 20, thereby causing the worm gear 72 of the gear set 24 to rotate in one direction and causing the segment gear 74 to rotate toward the commanded angular position. As the segment gear 74 rotates in one direction, the tab 84 engages one of the spring ends 102, 104 (depending on direction), causing that spring end to move conjointly with the segment gear 74, and thereby tending to coil or more tightly wrap the coils of the spring 100. As such, the other spring end engages the tab 86 which moves in response to the torsional force of the coil spring 100, thereby moving the carrier 30 in the same rotational direction as the segment gear 74. As the carrier 30 rotates, the magnet 90 and the output shaft 22 rotate conjointly therewith. Thus, coupler 66, worm gear 72, segment gear 74, coil spring 100, carrier 30, magnet 90, and output shaft 22 are all part of a set of driven components controlled by motor 20 and, although in the illustrated embodiment sensor 28 monitors the position of carrier 30 via magnet 90, the sensor (whether a Hall effect sensor, photo-optic sensor or otherwise) can be coupled with any of these driven components to determine the position of output shaft 22. In this regard, where operation of the output shaft 22 is via a torque-limiting mechanism such as coil spring 100, the sensor can be located on the output shaft side of the coil spring, as in the illustrated embodiment, or can be located on the segment gear side even though movement of the segment gear does not necessarily exactly track movement of the output shaft 22.
Normally, the amount of travel of the segment gear 74 in either direction is limited in software by ECU 16 and/or controller 18. As shown in
As magnet 90 rotates with the carrier 30, the control circuit 18 monitors the flux direction and strength of the magnetic field impinging on the Hall Effect sensor 28. The voltage level of the position feedback signal from the Hall Effect sensor 28 is compared by the control circuit 18 to a voltage range programmed within the control circuit 18 to ensure that the received feedback signal voltage is within a valid range. Upon determining that the voltage level is proper, the actual angular position of the output shaft 22 is determined, which can be done in various ways, such as by using equations or a look-up table, for example. This sensed, actual position can then be compared by the control circuit 18 to the commanded position received from the ECU 16 and the resulting error used to adjust the position of the output shaft 22 until no error exists between the commanded and actual positions, or until the error falls to within an acceptable level. In this way, the control circuit 18 provides closed loop control of the position of output shaft 22, and this is done without involving the ECU 16 and, thus, without any additional computational effort by ECU 16. Other closed loop control schemes can be used in addition to or in lieu of proportional control, including integral and derivative control, and these control approaches can be used not only to achieve the commanded position, but if desired, to also control the speed at which the adjustments are made. For example, for larger angular adjustments, the rotational speed of the output shaft 22 could be increased. Such control schemes are known to those skilled in the art.
Once the output shaft 22 has reached its commanded position, as determined from the position feedback from sensor 28, the control circuit 18 interrupts power to the motor 20. Thereafter, the control circuit 18 will wait for a subsequent actuator command from ECU 16. Additionally, the control circuit 18 will periodically sample the angular position of the output shaft 22. If the output shaft 22 inadvertently moves from its commanded angular position, the control circuit 18 again activates the motor 20 to re-orient the output shaft 22 back to its commanded angular position. In addition to using the position feedback from sensor 28 for closed loop control, the control circuit 18 can also report the actual position back to the ECU 16, thereby providing confirmation of the output shaft 22 position.
The sensor 28 and control circuit 18 can also be used in conjunction with an external stop feature to determine whether the CMCV (not shown) that is being operated by the CMCV actuator 10 is present and functioning properly. In particular, the output shaft 22 can be connected to a linkage mechanism (partially shown in
Where an external stop member is used, CMCV actuator 10 can be programmed to move within a normal range of operation delimited at each end by a first target position. At either end of travel, this first target position corresponds to a desired CMCV “park” position, wherein the CMCV is in either its fully open or fully closed position. During normal use, the CMCV actuator can be commanded to drive its output shaft 22 to either of these positions or to any position in between. The actuator 10 is also programmed with a second target position at each end of travel that represents over-rotation of the valve beyond its park position and beyond the external stop member contained in either the CMCV itself or the linkage mechanism between the CMCV and output shaft 22. To detect that the CMCV is present and operating properly, the actuator 10 can be commanded to this second position in which case it drives the output shaft 22 to the first target position and then moves beyond that position at a reduced speed and torque until it either stops (due to the external stop member) or reaches the second target position. In either case, it returns position information back to the ECU 16 which uses that position information to determine whether it stopped due to the external stop member or whether it over-rotated. In the latter case, the ECU can send a diagnostic error to indicate the CMCV malfunction. The actuator 10 maintains the output shaft at this post-park position long enough for ECU 16 to obtain a position reading and then returns it to the first target (park) position or to some other position within the normal range of operation until further commands from ECU 16 are received. Other approaches for detecting over-travel of the output shaft can be used in addition to or in lieu of this first and second target position approach.
It will thus be apparent that there has been provided in accordance with the present invention a CMCV actuator 10 which achieves the aims and advantages specified herein. It will of course be understood that the foregoing description is of a preferred exemplary embodiment of the invention and that the invention is not limited to the specific embodiment shown. Various changes and modifications will become apparent to those skilled in the art, such as for example, attaching a magnet to the segment gear in addition to or in lieu of the magnet on the carrier, and positioning a sensor adjacent the segment gear to detect the position of the segment gear, and thus, the output shaft. Alternatively, non-magnetic sensors can be used in lieu of the disclosed Hall effect sensor; for example, any of those known in the art that use photo-detection or resistance to determine position. Further, the stop member could be positioned adjacent one of the gears in the gear set to prevent separation or disengagement of the gears from one another. All such variations and modifications are intended to come within the scope of the appended claims.
As used in this specification and claims, the terms “for example” and “such as,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
This application is a continuation-in-part of U.S. application Ser. No. 10/907,226, filed Mar. 24, 2005 which claims the priority of U.S. Provisional Application No. 60/556,122, filed Mar. 25, 2004. This application also claims the priority of U.S. Provisional Application No. 60/620,299, filed Oct. 20, 2004, the entire contents of which are hereby incorporated by reference.
Number | Date | Country | |
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60556122 | Mar 2004 | US | |
60620299 | Oct 2004 | US |
Number | Date | Country | |
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Parent | 10907226 | Mar 2005 | US |
Child | 11163495 | Oct 2005 | US |