Patent Application
20190120161
A conventional powertrain of a vehicle or a power plant uses an internal combustion engine to generate torque, with the engine coupled to a driven load via a power transmission arrangement. In lieu of an engine, an electric powertrain relies on electrical energy supplied by a multi-cell battery pack, a fuel cell stack, or another direct current (DC) power supply. Hybrid powertrains generate torque using either or both of an engine and an electric machine as prime movers, with operation of the prime movers determined and closely regulated by a hybrid controller in order to achieve optimal drive performance or fuel economy.
Of the above-noted powertrains, a hybrid powertrain in particular may be configured as a full/strong-type or a mild hybrid-type of powertrain. In a strong hybrid powertrain, motor output torque from one or more high-voltage electric machines is used as a primary source of torque in order to propel the vehicle. In contrast, a mild hybrid powertrain uses an electric machine to provide increased torque for cranking and starting the engine, e.g., after an idle fuel-conserving engine auto-stop event. Additionally, transient torque pulses may be delivered by the electric machine to the engine during engine auto-start/auto-stop events, as well as to reduce engine load as needed for optimal drive performance. The transient torque boost provided by the electric machine in a mild hybrid powertrain is intended to improve engine acceleration performance and starting time relative to an auxiliary starter motor.
A fuel injection control system is disclosed herein for use with an internal combustion engine, for instance with a diesel engine within a mild hybrid powertrain. In an example embodiment, the control system includes an auxiliary battery providing an auxiliary output voltage, a high-voltage (HV) battery providing an HV output voltage that is greater than the auxiliary output voltage, a switching circuit, a controller, and a fuel injector system. The switching circuit includes first and second switching pairs. The controller commands the opening and closing of individual switches of the switching pairs in order to inject an electrical current from a selected one of the auxiliary battery or the HV battery according to a predetermined injector current profile. The fuel injector system includes one or more control solenoids configured to control an injection of fuel into the engine's cylinders.
The control solenoids include wire coils or windings that are electrically connectable to the HV battery during a transient boost phase of the injector current profile, with connection to the HV battery occurring via opening of the switches of the first switching pair and closing of the switches of the second switching pair. The solenoid windings are electrically connectable to the auxiliary battery during separate peak, by-pass, hold, and end-of-injection phase of the fuel injection profile, which is accomplished by closing the first switching pair and opening the second switching pair.
The HV output voltage may be at least 48 VDC in some embodiments, such as when the engine is used as part of a mild hybrid electric powertrain.
The switching pairs may include a corresponding high-side switch that selectively connects the control solenoid(s) to the HV or auxiliary battery, with the particular battery based on the injector current profile, and a low-side switch selectively connecting the control solenoid(s) to electrical ground. The switching pairs may be optionally embodied as solid-state semiconductor switches.
The switching circuit may include a first diode having anode and cathode sides. The anode side is connected to electrical ground. The cathode side is connected to the high-side switches. A second diode has an anode side connected to the low-side switches and a cathode side connected to the HV battery.
A plurality of the control solenoids may be arranged in electrical parallel with respect to each other.
A vehicle is also disclosed herein that includes an internal combustion engine and the fuel injection control system noted above. The vehicle may include an electric machine that is electrically connected to the HV battery and powered by the HV output voltage. The vehicle may be optionally embodied as a mild hybrid electric vehicle, in which case motor output torque from the electric machine may be used to crank and start the engine.
The above summary does not represent every embodiment or every aspect of the present disclosure. Rather, the foregoing summary merely provides an exemplification of some of the novel concepts and features set forth herein. The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of illustrative embodiments and representative modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. Moreover, this disclosure expressly includes any and all combinations and subcombinations of the elements and features presented above and below.
The present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the drawings. Rather, the disclosure is to cover all modifications, equivalents, combinations, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.
Referring to the drawings, wherein like reference numbers refer to like components throughout the several views,
The engine 20 may include a flywheel 21 and a crankshaft 24. The crankshaft 24 is selectively connected to an input member 25 of a transmission (T) 26 via an input clutch CI. When the engine 20 is supplied by fuel (arrows F) from the FIS 22, engine torque is delivered to the transmission 26 via the coupled crankshaft 24 and input member 25. In response, the transmission 26 delivers output torque to the wheels 12F and/or 12R via a corresponding drive axle 28F or 28R, respectively.
The vehicle 10 may include an electric machine (ME) 30, such as a polyphase electric machine having a rotatable output shaft (not shown). When the electric machine 30 is energized via application of a polyphase voltage (VAC) to individual phase windings 35 of the electric machine 30, motor output torque (arrow TM) is ultimately generated and delivered to a coupled load. The flywheel 21 may act as a coupled load in a mild hybrid powertrain arrangement in which the engine 20 is cranked and started using the motor output torque (arrow TM). The electric machine 30 may be coupled to the engine 20 via a belted drive connection (not shown). Other possible implementations include connecting the electric machine 30 to the crankshaft 24, to the input member 25 of the transmission 26, to a gear member or drive element located within the transmission 26, or on one or both of the drive axles 28F and/or 28R. Therefore, the specific configuration of
The electric machine 30 may be optionally embodied as a three-phase/multi-phase traction motor or a motor/generator unit, with tensioners (not shown) accommodating torque in both rotational directions when the electric machine 30 is embodied as a motor/generator unit. The phase windings 35 carry a corresponding phase current in the depicted polyphase configuration. In various example embodiments, the electric machine 30 may be constructed as an induction machine or as a synchronous machine with or without permanent magnets within its rotor, without limitation.
The vehicle 10 of
The PIM 32, which is electrically connected to the phase windings 35 of the electric machine 30, includes switching pairs of upper/high-side and lower/low-side switches, with the terms “upper” and “high-side” referring to connection to a voltage source, i.e., the auxiliary battery 38 or HV battery 34, and “lower” or “low-side” referring to connection at a lower potential/electrical ground (GND). The semiconductor switches (not shown) of the PIM 32, as understood in the art, may be embodied as voltage-controlled, bipolar solid-state switches, e.g., insulated gate bipolar transistors (IGBTs), metal-oxide semiconductor field effect transistors (MOSFETs), wideband GaN devices (WBG), or other suitable switches having a corresponding gate to which a gate signal is applied to change the on/off state of a given switch.
A controller (C) 50 is in communication with the PIM 32 and the FIS 22 over a controller area network or other communication bus, and may be variously configured as a single device or as distributed control devices. Although omitted from
The controller 50 shown in
Referring briefly to
Referring to
During the boost phase (BST) shown in
At the conclusion of the by-pass phase (BP), the electrical current from the auxiliary battery 38 of
Further with respect to the switching circuit 56, the control solenoids 22A and 22B are connected via the high-side switches SW1H and SW2H to one of the HV battery 34 providing a high-voltage level (VHV) and auxiliary battery 38 providing an auxiliary-voltage level (VAUX). First and second diodes D1 and D2 may be used to protect the switching circuit 56 from reverse current flow, with the internal resistance of the control solenoids 22A and 22B represented by a respective series resistor R3 and R4. The first diode D1 may have an anode side 43 connected to electrical ground (GND) and a cathode side 41 connected to the high-side switches SW1H and SW2H. The second diode D2 has an anode side 41 connected to the low-side switches SW1L and SW2L and a cathode-side 43 connected to the HV battery 34. Current-limiting resistors R1 and R2 may be connected in series with the respective control solenoids 22A and 22B as shown.
Control of the switching circuit 56 is regulated by the controller 50. During the boost phase (BST) of
The FIS 22 and vehicle 10 described above enable a relatively low-cost implementation of a solenoid-controlled high-pressure fuel injection process, for instance within a 48 VDC mild hybrid powertrain. Attendant benefits of the disclosed boost architecture include improved thermal dissipation, control complexity, and architecture simplification. As the injection control system 60 of
While aspects of the present disclosure have been described in detail with reference to the illustrated embodiments, those skilled in the art will recognize that many modifications may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise construction and compositions disclosed herein; modifications, changes, and/or variations apparent from the foregoing descriptions are within the scope of the disclosure as defined in the appended claims. Moreover, the present concepts may expressly include combinations and sub-combinations of the preceding elements and features.
