This invention relates in general to boosted intake internal combustion engines and supercharger bypass control mechanisms. In particular, this invention relates to electronically controlled, variable position backstops to regulate an output pressure bypass state of a supercharger.
Superchargers are well known in the art as a means to increase output power of an internal combustion engine. These devices increase the volume of air/fuel mixture admitted into an engine in order to generate additional power from the larger charge admitted into the combustion chamber. Roots-type and screw-type superchargers are known in the art and often utilize a vacuum actuated bypass to regulate the amount of boost admitted based on engine operating conditions. In certain instances, centrifugal style superchargers also utilize a similar vacuum bypass actuator. It is well known that these types of superchargers are mechanically coupled to the engine and spin at a speed proportional to the engine speed. In operation, superchargers force more air into the engine than could normally be aspirated without the addition of the supercharger. However, maximum engine performance is not always desired for every operating condition. A constantly running supercharger produces ill effects when maximum power output is not utilized or required. In particular, increased pressure on engine components produces excessive wear and reduced drivability at part-load operating levels. Manufacturers of supercharger kits utilize methods to selectively bypass or re-circulate the forced air back to the compressor inlet or vent it to the atmosphere. This bypassing or recirculation minimizes any negative effects when maximum performance is not needed, but certain operating conditions can cause drivability issues. In addition, maximum boost is not always desired, but currently there is no way to provide “partial” boost reliability with a vacuum actuated bypass valve.
Roots or screw type supercharger are positive displacement superchargers that pump a fixed volume of air into the engine every revolution. The pressure or boost curve of these units is relatively flat, meaning that regardless of engine RPM boost remains relatively constant. When the supercharger is “activated” by the bypass value closing, there is an abrupt or violent transition from no boost to full boost, regardless of engine RPM. The more boost the supercharger makes, the more violent this transition from the “off” or non-boosted state to the “on” or boosted state.
Regardless of supercharger design, a typical vacuum actuated bypass valve can effectively only maintain two states, either open or closed. The valve is constructed with a spring biasing the supercharger operating state to either an open or closed state at rest. The valve actuation is controlled solely by the intake manifold vacuum/pressure. One drawback to these vacuum actuated valves is that their operation is fairly unstable ‘in-between’ opening and closing. It is difficult to hold the valve steady at a fixed position in an intermediary state during normal driving. The exact opening and closing pressures vary between applications, but typically the valve closes at an absolute manifold pressure in the range of 75-95 kpa.
Regardless of supercharger type, drivability issues are even more apparent if a vehicle is up-fitted with an aftermarket camshaft (high lift, high overlap cam lobe profile) that reduces the engine's ability to create vacuum. There are many aftermarket camshafts that increase the manifold pressure (reduce the engine's ability to create vacuum) to 75-85 kpa during cruising conditions. These camshaft configurations tend to force the Existing bypass valve open and closed almost the entire time during the driving cycle. This greatly reduces the drivability of the vehicle as the vehicle constantly fluctuates between a boosted and non-boosted state as the bypass valve is controlled only by manifold vacuum.
Other attempts to address drivability issues by regulating boost levels focus on shifting bias strategies of the vacuum valve. For example, U.S. Pat. No. 8,046,997 to Bell et al., shifts the bias of the valve from a normally closed state to a normally open state. Rather than using engine manifold vacuum to open the bypass valve, as is the typical configuration, the Bell device uses the boost created from the supercharger to initiate the bypass valve closing event. This valve closing event is initiated at a boost pressure of approximately 7 kPa over atmospheric, and fully closes the valve at approximately 42 kPa over atmospheric. This solution tends to be extremely limited, and applicable mainly to applications where a screw-type supercharger creates boost pressures well in excess of 42 kPa for a majority of the time in order to be efficient. This solution does not allow the flexibility of opening and closing the existing bypass valve at varying times. The Bell device control is fixed mechanically based on the springs used in the valve, and its operation is solely based on manifold pressure.
Thus, it would be desirable to regulate the boost level of a supercharger with greater precision and regard to specific driving conditions or demands.
This invention relates in general to boosted intake internal combustion engines and supercharger bypass control mechanisms. In particular, this invention relates to electronically controlled, variable position backstops to regulate an output pressure bypass state of a supercharger. This invention improves drivability of a vehicle equipped with a supercharger (typically aftermarket) utilizing a vacuum actuated bypass (a.k.a recirculation, anti-surge) valve by limiting or actively regulating the boost delivered to the engine based on one or more vehicle inputs. In certain embodiments, the invention achieves this improvement by limiting the effectively closed position of the bypass valve or boost control valve. In other embodiments, the invention regulates boost control by using an actuator assembly to position the boost control valve or bypass valve in a desired flow condition based on the one or more vehicle inputs. This invention can be used in roots and screw type superchargers that utilize a vacuum actuated bypass, but can also be utilized in centrifugal style superchargers with a similar vacuum bypass actuator.
In one embodiment, the invention is configured as an electronically controlled, variable position stop that effectively limits the fully closed position of an existing vacuum/pressure actuated bypass valve in an aftermarket supercharger. It utilizes a microcontroller to read data from the vehicle, interprets the signals, and controls an actuator to adjust a stop that will not allow the existing bypass valve to close all the way. The device does not affect the existing vacuum actuators normal operating state, but the effective “closed” position is limited externally utilizing the inventive backstop device and software control protocol. This results in being able to clip the boost that is delivered to the engine which can be precisely and variably controlled by the accelerator pedal position and/or other variables available.
In another embodiment, the invention is configured as a boost regulator that replaces an existing vacuum/pressure actuated bypass valve with an electronically controlled and actuated bypass valve system. The boost regulator uses a motor, and may include an associated geartrain, to position the bypass valve in a desired flow position, such as fully open, partially open, or fully closed, to regulate the supercharger boost condition.
As one illustrative example of the benefits of the inventive backstop control, a track vehicle can be outfitted with an aftermarket positive displacement supercharger that outputs 12 lbs. of boost throughout the RPM band. With a typical vacuum actuated bypass valve, there is no reliable way of limiting boost to 7 lbs. of boost at 50% accelerator pedal position (APP), and 10 lbs. of boost at 75% APP, and also to allow full boost at 100% APP. The backstop device allows a boost control profile to adjust the effective closed position of the existing bypass valve. Alternatively, the boost regulator embodiment permits control of the effective closed position of the boost control valve directly by controlling the actuator position. The profile provides a more linear power curve based on accelerator pedal position than can be provided by a typical “drive by cable” naturally aspirated engine.
In another illustrative example, in straight line, full power acceleration events (a.k.a. drag racing). it may be desirable to limit supercharger boost in a first gear launch scenario to limit wheel slip and maximize power transfer to the pavement. The backstop and control protocol enables a boost control profile to be tailored to specific boost ranges for different RPM ranges and/or transmission gear positions. For this example, one such protocol may be configured to limit boost to 7 lbs. in first gear under 4000 rpm and gradually increase boost to a maximum from 4000 RPM to an upper RPM level such as engine redline. The system may further be configured to provide maximum boost in all of the other gears. In other protocols, certain operating configurations may have boost truncated or completely bypassed in certain transmission gear modes. In one aspect, the backstop may be actuated to maintain the bypass valve in the wide open position, or alternatively in other partially opened positions to limit boost in overdrive gear ranges. Such an operational protocol can prevent damage to gear trains, such as overdrive gears that are not capable of handling boosted power output. Other custom boost limiting profiles can be created using a variety of existing vehicle sensors.
In one embodiment of the invention, a closed-loop controlled DC motor is remotely mounted from the existing bypass valve. The motor actuates a cable connected to the variable stop. The backstop pivots independently on the existing shaft that controls the internal butterfly valve of the bypass. The backstop includes one or more intermediate steps or positions that limits the closing of the valve by restricting movement of the existing bracket on the end of the shaft. Alternatively, the backstop may be mounted to pivot on a different pivot axis.
In yet another embodiment of the invention, the backstop may be configured as a variable movement plunger, connected to either the diaphragm of the actuation valve or mounted to the intake, supercharger, or other mounting surface and actuate against a stop of the pivot associated with operation of the butterfly valve. This configuration can effectively limit the linear motion of the plunger or the diaphragm. Further, another actuation mechanism may utilize a worm gear/shaft type setup where the variable position stop is part of, or attached to, a worm gear that rotates the stop. These alternative variable stops can be actuated directly, or indirectly via any type of motor or solenoid to control the valve position. This includes, but is not limited to, DC motors, AC motors, stepper motors, and servo motors, along with pneumatic or hydraulic actuators and motors.
In yet another embodiment, the boost regulator is configured to replace the dashpot actuator and utilize the above-referenced motor controls to directly control actuator position to tailor boost output to specific driving conditions, regardless of manifold absolute pressure values.
Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
Referring now to the drawings, there is illustrated in
The boost control profile 110 is capable of receiving multiple data inputs indicative of different vehicle components and their related operational states to determine a desired position of the boost control valve 134. In one aspect of the invention, the supercharger boost control assembly 100 is capable of altering the boost, or supercharger output, delivered to the engine by utilizing a direct user input parameter, such as accelerator position, rather than only relying on a secondary or time-lagged signal such as manifold vacuum. The boost control profile 110 is configurable or programable to operate the boost regulator 108 based on data from multiple vehicle operation parameters which are indicative of a desired boost demand. In one example of a boost control profile, the boost regulator 108 is capable of adjusting the supercharger to provide about 7 pounds of boost at a 50% accelerator pedal position (APP), 10 pounds of boost at 75% APP, and allow full boost at 100% APP.
The boost regulator 108 includes a housing 114 having a support casing 114a, a front cover 114b, and a back cover 114c. While the connector 112 is illustrated as part of the front cover 114b, any part of the housing 114 may be a suitable location for the connector 112. The housing 114 may be formed from any material such as plastic, composite, or metal, and the front and rear covers 114b, 114c may be secured to the support casing 114a by retainers 136, such as clips, screws, or other fastener elements. In the illustrated embodiment, the functional elements of the boost regulator 108 are located relative to each other in the support casing 114a. A motor 116 includes a drive gear 118 that engages a first gear or driven portion 120a of a transmission gear 120. A second gear or driving portion 120b of the transmission gear 120 engages a sector gear 122. The motor 116 may be any type of motor such as, for example, a DC motor, closed-loop controlled DC motor, stepper motor, servo motor, or variable reluctance motor. The sector gear 122 rotates a shaft 124 that is connected to an actuator link 128. The shaft 124 may include a support bearing 124a. The actuator link 128 is moved between a first stop position and a second stop position. The actuator link 128 is biased into one of the first or second stop positions by a resilient element such as a spring 126. A position indicator 144, such as a potentiometer or encoder, is connected to the sector gear 122 or shaft 124 to indicate the position of the boost control valve 134 relative to an output bore of the supercharger. Collectively, the sector gear 122, shaft 124, spring 126, and actuator link 128 may form a boost actuator assembly 146.
A connecting linkage 130 transfers movement of the actuator link 128 to a boost valve arm 132 which moves the boost control valve 134 between a first boost control valve position and a second boost control valve position. In certain embodiments, the first boost valve control position may be a closed or no boost position and the second boost control valve position may be an opened position that includes any partially opened position defining a partial percentage of boost condition or a fully opened position defining a full boost condition. The connecting linkage 130 may be any linkage configured to move the boost valve arm 132 and/or the boost control valve 134. In the illustrated embodiment, the connecting linkage 130 is configured with a first clevis or yoke 130a connected to the actuator link 128 and a second clevis or yoke 130b connected to the boost valve arm 132. The connecting link 130 may also be adjustable lengthwise between the two devises.
In certain embodiments, the support casing 114a of the housing 114 defines a motor compartment 138 to accommodate motor 116, a spring compartment 140 to locate and secure spring 126, and a bearing compartment 142 to locate support bearing 124a. The support casing 114a may include bosses configured as a first stop 143 and a second stop 145 that limit rotational travel or define overall travel limits of the sector gear 122 and thus the boost control valve.
In operation, the controller 102 receives data from the one or more vehicle operation parameter inputs 104 related to driver inputs to vehicle (primary inputs) and/or operating conditions of the vehicle (secondary inputs). These operating conditions may include primary inputs such as accelerator position, gear selection, and/or clutch pedal position and secondary inputs such as vehicle acceleration, engine RPM, engine or powertrain torque, manifold absolute pressure level, mass air flow data, vehicle speed, vehicle acceleration, temperature, or other input signals from any vehicle sensors. The controller 102 further receives positional information regarding the boost control valve 134 from the position indicator 144. The controller 102 processes the vehicle operation parameter inputs 104 with the boost control profile 110 to determine the amount of actuation needed from the boost actuator assembly 146 to achieve the desired boost level from the supercharger. The controller then energizes the motor 116 to drive the sector gear 122, actuator link 128, and boost control valve 134 from a first boost control valve position to a second boost control valve position. In certain operating conditions where boost is desired, the first position may be a closed boost valve position and the second boost valve position may be a partially or fully opened boost valve position. In certain embodiments, the second stop position may be the fully opened boost valve position, and the controller determines an intermediate or third stop position related to a partial boost condition. The controller is configured to determine a potentially infinite number of intermediate boost condition positions in response to the vehicle operational parameter inputs and the boost control profile. In certain embodiments, the motor 116 drives in one direction and the resilient member 126 provides a return actuation force when the motor is deenergized. Alternatively, the motor 116 may be configured to drive in both directions and the resilient member 126 provides a failsafe, boost closed position should the motor 116 fail.
Referring now to the drawings, there is illustrated in
As shown in
Referring again to
The variable position backstop 210 includes a seat 224 that locates against a contact surface 226 of the boost control arm 216 to limit the overall movement thereof. In
The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.
This application claims the benefit of U.S. Provisional Application No. 63/355,753, filed Jun. 27, 2022, the disclosure of which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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63355753 | Jun 2022 | US |