An apparatus and method for controlling an engine stop position

Abstract

An electric starting system for an internal combustion engine includes a pinion gear, a pinion solenoid device coupled to the pinion gear, a starter motor selectively connectable to a flywheel of the engine through the pinion gear, and a controller in communication with the pinion solenoid device and the starter motor. In response to an engine auto-stop signal, the controller is configured to transition the pinion gear into contact with the flywheel and the motor and rotate an engine crankshaft to a predetermined crank angle. In response to an engine auto-start signal, the controller is configured to command transfer of motor torque from the starter motor to the flywheel through the pinion gear and for a period of time sufficient to start the engine.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an apparatus and method for an engine start-stop system (useful in a vehicle powertrain). BACKGROUND

[0002] When an engine is started from a stopped condition, internal combustion engines typically use an electric starter motor to turn the engine crankshaft to initiate combustion in the engine. In some vehicle applications, a start-stop system is used in which the engine is automatically turned off when the vehicle does not need to be propelled (herein referred to as an automatic stop event) to conserve fuel, and automatically restarted when vehicle drive torque is required (herein referred to as an automatic start event). This automatic stopping and restarting can result in problems in terms of noise, vibration, and harshness (NVH) perceived by the vehicle occupants.

[0003] Accordingly, while current start-stop systems achieve their intended purpose, there remains a need for a new and improved system and method for vehicle engine start-stop operation. SUMMARY

[0004] According to several aspects, an electric starting system for an internal combustion engine having a flywheel with a flywheel gear connected to an engine crankshaft is disclosed. The electric starting system includes a pinion gear, a pinion solenoid device coupled to the pinion gear, a starter motor selectively connectable to the flywheel of the engine through the pinion gear, and a controller in communication with the pinion solenoid device and the starter motor. The controller is configured to command the engine to shut down in response to an engine automatic stop signal and determine an engine speed after the engine is shut down. In response to the engine speed being less than a first threshold speed, the controller is configured to command a control current to be delivered to the pinion solenoid device at a peak current level to thereby transition the pinion gear into contact with the flywheel and the motor. In response to the engine speed being less than a second threshold speed, the controller is configured to provide a pulse width modulation (PWM) excitation to the starter motor to cause the starter motor to rotate to thereby cause the pinion gear to fully engage with the flywheel and cause the engine crankshaft to rotate to a predetermined crankshaft angle, and to stop providing the PWM excitation to the starter motor when the engine crankshaft reaches the predetermined crankshaft angle. After the pinion gear fully engages with the flywheel, the controller is further configured to deliver a pulse width modulation (PWM) pinion control signal at a different voltage to deliver the control current to the pinion solenoid device at a fluctuating holding current level that is a non-zero value less than the peak current level. In response to an engine automatic start signal, the controller is further configured to command a motor torque to be delivered from the starter motor to the flywheel through the pinion gear while maintaining the control current at the holding current level for a time sufficient to start the engine.

[0005] In another aspect of the application, the electrically activated system includes two independently controllable devices for delivering current to the starter motor.

[0006] In another aspect of the application, one of the two independently controllable devices for delivering current to the starter motor includes a motor solenoid, and the other of the two independently controllable devices for delivering current to the starter motor includes a semiconductor switching device.

[0007] In another aspect of the disclosure, a pulse width modulated (PWM) excitation is provided to the starter motor by the semiconductor switching device.

[0008] In another aspect of the disclosure, an excitation is provided to the starter motor by the motor solenoid to transfer motor torque from the starter motor through the pinion gear to the flywheel while maintaining a control current at a hold current level for a time sufficient to start the engine.

[0009] In another aspect of the disclosure, the pinion solenoid device and the starter motor are powered by an auxiliary voltage bus at a nominal voltage level of 15V or less.

[0010] According to several aspects, a method for controlling an electrically activated system of an internal combustion engine having a flywheel is disclosed. The method includes commanding, in response to an engine automatic stop signal, an engine shutdown by a controller and determining, by the controller, when an engine speed of the engine is less than a first threshold speed. The method further includes commanding, in response to the engine speed being less than the first threshold speed, a current transfer by the controller to a pinion solenoid device at a peak current level to thereby transition a pinion gear connected to the pinion solenoid device into contact with the flywheel. The method further includes commanding, in response to the engine speed being less than a second threshold speed, a starter motor rotation to thereby fully engage the pinion gear with the flywheel and rotate an engine crankshaft to a predetermined crank angle, and after the pinion gear is fully engaged with the flywheel, transmitting a pulse width modulated (PWM) pinion control signal at a different voltage to transfer a control current to the pinion solenoid device at a fluctuating hold current level that is a non-zero value less than the peak current level. The method further includes commanding, in response to an engine automatic start signal, a transfer of motor torque from a starter motor through the pinion gear to the flywheel while maintaining the control current at the hold current level and holding the motor torque by the controller for a time sufficient to start the engine.

[0011] According to several aspects, a powertrain includes: an internal combustion engine having a flywheel with a flywheel gear; a transmission connected to the engine; a load coupled to the transmission; an electric power source configured to output an electric current; a pinion gear; a pinion gear solenoid device coupled to the pinion gear and configured to be activated in response to the electric current from the electric power source, thereby moving the pinion gear into meshing contact with the flywheel gear of the flywheel; a starter motor having a motor gear that is selectively connectable to the flywheel gear of the engine flywheel through the pinion gear by activating the pinion gear solenoid device; and a controller in communication with the pinion gear solenoid device and the starter motor. In response to an engine automatic stop signal, the controller is configured to command the engine to shut down; determine an engine speed of the engine after the engine has shut down; and in response to the engine speed being less than a first threshold speed, command a control current to be delivered to the pinion gear solenoid device at a peak current level, thereby transitioning the pinion gear into contact with the flywheel and the motor. The controller is further configured to: in response to a predetermined delay time having elapsed after the control current is initially delivered to the pinion gear solenoid device at the peak current level, command a pulse width modulated (PWM) pinion gear solenoid control signal to be transmitted at a different voltage to deliver the control current to the pinion gear solenoid device at a fluctuating holding current level, the holding current level being a non-zero value that is less than the peak current level. In response to the engine speed being less than a second threshold speed, the controller is further configured to: command a pulse width modulated (PWM) motor control signal to be delivered to the starter motor to cause the starter motor to rotate, thereby causing the pinion gear to fully mesh with the flywheel and causing the engine crankshaft to rotate to a predetermined crankshaft angle, and to stop transmitting the PWM motor control signal when the engine crankshaft reaches the predetermined crankshaft angle. In response to an engine automatic start signal, the controller is further configured to: command the motor torque to be transferred from the starter motor to the flywheel through the pinion gear while the control current is maintained at the holding current level for a time sufficient to start the engine.

[0012] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0013] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.

[0014] Figure 1 is a schematic diagram of an exemplary electric start system for an engine.

[0015] Figure 2 is Figure 1 is a time plot of various bit flags and nominal control values available in overall control of the electric start system shown.

[0016] Figure 3is described for controlling Figure 1 a flowchart of an exemplary embodiment of a method of pre-engagement of the pinion and engine crank angle in the electric starting system shown.

[0017] The present disclosure is susceptible to various modifications and alternative forms, specific embodiments of which are shown by way of example in the drawings and are herein described in detail. The inventive aspects of this disclosure are not limited to the particular forms disclosed. Rather, the present disclosure is intended to cover modifications, equivalents, combinations, and alternatives falling within the scope of the disclosure as defined by the appended claims. DETAILED DESCRIPTION

[0018] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application or uses.

[0019] Reference is made to the accompanying drawings in which like reference numerals refer to like parts throughout the several views. Figure 1 An exemplary powertrain system 10 is schematically shown having an engine 20 coupled to a flywheel 32 through a crankshaft 31, for example, to a ring gear or other drive mechanism connected thereto. The powertrain system 10 further includes an electric starting system 12 operable to automatically start and launch the engine 20 during an engine automatic start event, for example, after the engine 20 has been shut down at idle. The electric starting system 12 can include or be connected to a direct current (DC) battery pack 14, for example, a multi-cell lithium-ion, nickel-metal hydride, or lead-acid battery pack having positive (+) and negative (-) terminals. The battery pack 14 can be an auxiliary battery pack, for example, having a nominal voltage at an auxiliary level, for example, about 12 to 15 VDC.

[0020] The electric starting system 12 disclosed herein includes a permanent magnet brush motor, hereinafter referred to as a starting motor 18. The starting motor 18 provides launch torque to support the start-stop function of the engine 20. The starting motor 18 includes a rotor 19 coupled to a gear system 11, which can include a planetary gear system, by way of non-limiting example. The electric starting system 12 further includes a pinion solenoid device 21 coupled to a pinion 33 through a shaft 190, the pinion 33 being selectively engageable with the flywheel 32 by operation of the solenoid device 21.

[0021] As described below with reference to Figure 2 and Figure 3To explain further in detail, controller 50, such as the engine control module in the exemplary vehicle embodiment, is configured to execute method 100 in the overall control of the torque operation of starter motor 18. This occurs during and after an automatic start event of engine 20. Unlike a permanently engaged starter motor using a one-way clutch disposed between crankshaft 31 and flywheel 32, such a component rotates continuously with engine 20, this method instead employs separate solenoids that control the pinion and energize the brush starter motor within the electric start system 12. Therefore, this method is able to reduce power operation and prolong the engagement time of pinion 33 with flywheel 32 during automatic stop / start events of engine 20.

[0022] Specifically, when engine 20 is in automatic stop mode and engine speed (N) 20 When the speed is below the calibration threshold, controller 50 executes the logic embodying method 100 as part of the pinion pre-engagement scheme. Controller 50 controls the pinion solenoid drive circuit 21D to supply current to the pinion solenoid assembly 21. The pinion solenoid drive circuit 21D includes a first semiconductor switching device 52, depicted as a MOSFET, whose switching state is controlled by a first gate drive circuit 54 in response to a pinion solenoid control signal 56 from controller 50. When the pinion solenoid assembly 21 is energized, the pinion 33 engages with the flywheel 32, thereby engaging with the engine 20, until a restart operation of the engine 20 is completed using the starter motor 18. After a predetermined duration, controller 50 reduces the voltage or current level supplied to the pinion solenoid assembly 21, for example, through pulse width modulation (PWM) or other suitable electronic switching control techniques. In this way, controller 50 keeps the pinion 33 engaged with the flywheel 32, for example, with the spline or gear members connected thereto, without overheating the pinion solenoid assembly 21. Although described as a MOSFET, it should be understood that the first semiconductor switching device 52 may be implemented as another type of semiconductor device, such as an IGBT, GaN FET, or SiC MOSFET with suitable first drive circuitry 54, without departing from the spirit and scope of this disclosure.

[0023] Continue to refer to Figure 1 The exemplary embodiments depicted include two controllable power supplies of voltage or current for driving the starter motor 18. The electric starting system 12 may include a motor solenoid assembly 16 configured to electrically connect the battery pack 14 to the permanent magnet DC brushed motor 18. A motor solenoid control signal 17 from the controller 50 allows the controller 50 to set the switching state of the starter motor 18. For clarity, although shown separately from the starter motor 18, the motor solenoid assembly 16 and the starter motor 18 may be integrated components. Figure 1The illustrated embodiment also includes a motor drive circuit 18D electrically connected to the starter motor 18. The motor drive circuit 18D includes a second semiconductor switching device 40, depicted as a MOSFET, whose switching state is controlled by a second gate drive circuit 42 in response to a motor command signal 44 from a controller 50. Motor torque (arrow T M ) from the starter motor 18 is used to control the rotation of the pinion gear 33 to ensure that the pinion gear 33 is fully seated on the gear system 11 and to advance the engine crank position to a desired crank angle, thereby reducing the time required to restart the engine during an automatic start event. The controller 50 can control the motor voltage or current by providing a PWM motor command signal 44 to advance the motor 18 to the desired crank angle. In this way, the methods described herein are intended to help eliminate the noise, vibration, and acoustic roughness that can occur during an automatic start event due to less than ideal gear meshing. While depicted as a MOSFET, it should be understood that the second semiconductor switching device 40 can be implemented as another type of semiconductor device, such as an IGBT, GaN FE, or SiC MOSFET with an appropriate first drive circuit 42, without departing from the spirit and scope of the present disclosure.

[0024] Furthermore, with respect to the powertrain system 10 and electric starting system 12 as illustrated in Figure 1 , the engine 20 can be implemented as a gasoline or diesel engine and ultimately outputs engine torque to an output shaft 24. The output shaft 24 can be coupled to a transmission 22, for example, through a torque converter or clutch (not shown). The transmission 22 ultimately delivers output torque to a transmission output member 25 at a particular gear or speed ratio. The output member 25 in turn drives a coupled load, Figure 1 depicted in Figure 1 , is a set of drive wheels 26 in an exemplary automotive application. Other beneficial applications of the powertrain system 10 can be envisioned, including power plants, robots, mobile platforms, and non-automotive vehicle applications, such as watercraft, ships, rail vehicles, and aircraft, and thus the automotive vehicle embodiment of

[0025] is intended for illustration and not limitation of the disclosed concepts. Figure 1 When an automatic stop event occurs while the engine 20 is not running, for example, when the engine 20 is idling or coasting, the electric starting system 12 can respond to an automatic start command from the controller 50 to automatically energize electrically, thereby selectively delivering starter motor torque (arrow T M ) to the flywheel 32. One possible configuration to achieve these objectives is to use a pinion solenoid device 21 as illustrated in

[0026] When pinion solenoid device 21 is energized in response to a pinion solenoid control signal 56 from controller 50, pinion solenoid device 21 linearly translates pinion gear 33 to the position indicated at 33A, thereby directly contacting and engaging the mating teeth or splines on flywheel 32 and gear system 11. Once engine 20 has been started, the pinion solenoid control signal is then set to a state that de-energizes pinion solenoid device 21. Pinion gear 33 is then urged out of engagement with flywheel 32 by the return action of pinion solenoid device 21. Other configurations can also be possible to selectively engage pinion gear 33 with flywheel 32 and gear system 11, and thus the illustrated embodiment is intended to illustrate the general concepts disclosed herein without limiting electric starter system 12 to this embodiment.

[0027] Thus, in a vehicle embodiment of power system 10, pinion solenoid device 21 can be powered by a PWM voltage controlled by controller 50. In one possible embodiment, controller 50 can be electrically connected to pinion solenoid device 21 and starter motor 18 by separate control lines, and the voltage level of each control line can reach the voltage level of battery 14.

[0028] Figure 1 The illustrated controller 50 is configured to receive measured voltages, currents, positions, temperatures, and / or other suitable electrical values as part of a set of input signals (arrow CC I ). As part of method 100, controller 50 can be implemented in different ways as one or more control devices that collectively manage motor torque (arrow T M ) from starter motor 18. Controller 50 is configured to control pinion solenoid device 21 through pinion solenoid control signal 56 while enabling and energizing starter motor 18 through motor solenoid control signal 17, where pinion solenoid control signal 56 and motor solenoid control signal 17 can be transmitted through separate control lines or a transmission connector. Thus, a PWM voltage signal can be provided to pinion solenoid device 21 to enable soft / low noise engagement and hold current, which helps to maintain pinion gear 33 in a pre-engaged state during an auto-stop condition.

[0029] Multiple controllers can communicate through a serial bus (e.g., CAN bus 35), other differential voltage networks, or through discrete conductors. Pinion solenoid device 21 can be responsive to a pinion solenoid drive circuit 21D, which can be located in controller 50 or starter motor 18 in different embodiments.

[0030] The controller 50 can include one or more digital computers, each having a processor (P), such as a microprocessor or central processing unit, and memory (M) in the form of read only memory, random access memory, electrically programmable read only memory, etc., high speed clocks, analog to digital and digital to analog circuitry, input / output circuitry and devices, and appropriate signal conditioning and buffer circuitry. The controller 50 can also store algorithms and / or computer executable instructions in the memory (M), including underlying algorithms or code implementing the method 100 described below, and transmit commands to the electric starting system 12 to implement certain control actions in accordance with the present disclosure.

[0031] The controller 50 is in communication with the engine 20 and receives signals as part of the input signals (arrow CC I ) and indicative of the rotational speed and temperature of the engine 20, as well as other possible engine operating states or parameters. Such parameters include a request for starting of the engine 20, whether operator initiated or autonomously generated. The controller 50 is also in communication with the starting motor 18 and thus receives signals indicative of the current rotational speed, current draw, torque, temperature, and / or other operating parameters. The controller 50 can also be in communication with the battery pack 14 and receive signals indicative of the state of charge, temperature, and current draw of the battery, as well as the voltage across the DC voltage bus 15. In addition to transmitting torque requests to the starting motor 18 through the motor solenoid control signal 17, the controller 50 can also transmit output signals (arrow CC O ) to the engine 20 and transmission 22 as part of the overall operational functionality of the controller 50.

[0032] Referring to the trace 60, Figure 2 as part of the method 100, the controller 50 is configured to set an engine start flag, such as a binary 1 or 0 bit flag, to enable the starting motor 18 and pinion solenoid arrangement 21 to be controlled in a subsequent engine start event following an automatic stop state. Control parameters evaluated as part of the method 100 can include the bit flags 61 and 62. Figure 2 The bit flag 61, Figure 1 corresponds to an active automatic stop state, when, 20 the engine 20 is shown in the off state, i.e., not running, and the engine rotational speed (N Figure 2 continues from about tl to t3. Then, when the controller 50 commands a restart of the engine 20, the bit flag 62 is sent to a high state, such as a binary 1 as shown in the figure, from t4 and continues until t5.

[0033] At tl, the controller 50 sets another bit flag 63, indicating that pre-engagement of the pinion 33 is enabled in the logic of the controller 50. This pinion enable state continues until the restart event at t5 is completed. Thus, the bit flags 61, 62, and 63 correspond to TRUE / FALSE logic states, where a high value (e.g., 1) is TRUE and a low value (0) is FALSE.

[0034] At t2, which is reached shortly after the pinion solenoid 21 is activated, the controller 50 also energizes the starter motor 18, as shown by the motor voltage traces 64A and 64, which vary between 0V and 12V in the nominal 12V auxiliary embodiment of the DC voltage bus 15 shown. Figure 1 As shown in the portion of the motor voltage traces 64A marked 64B, the starter motor 18 is energized with a PWM voltage during the time interval from t2 to t5. In the exemplary embodiment, the PWM voltage is provided by the motor drive circuit 18D, as shown in the motor drive circuit 18D diagram. Figure 2 As shown in the portion of the motor voltage traces 64A marked 64A, the starter motor 18 is alternately energized and de-energized with a PWM voltage during the time interval from t2. In the exemplary embodiment, the PWM voltage is provided by the motor drive circuit 18D, as shown in the motor drive circuit 18D diagram. Figure 1 As shown in the motor drive circuit 18D diagram, the motor drive circuit 18D provides PWM drive to the starter motor 18 and provides the PWM signal as the motor command signal 44.

[0035] Figure 2 It is also shown that the PWM voltage 65A and 65 varies between 0V and 12V in the nominal 12V auxiliary embodiment of the DC voltage bus 15 shown. Figure 1 Thus, between tl and t2, which is the initial pre-engagement of the pinion solenoid 21 before the starter motor 18 is enabled, the full bus voltage is delivered to the pinion solenoid 21, as shown by the initial PWM voltage 65A. The PWM voltage 65A is sufficient to cause the pinion 33 to overcome friction and begin to move. Between t2 and t5, the controller 50 controls the pinion solenoid 21 at a lower voltage level, thus the power is reduced, as shown by the reduced duration or duty cycle of each pulse of the PWM voltage 65 relative to the initial PWM voltage 65A. Figure 1

[0036] The response to the PWM voltage 65A and 65 is the actual coil current 66, which describes the current in amperes that is delivered to the pinion solenoid 21. The coil current 66 initially rises to a peak current (I P ) at t2, and then stabilizes to a lower holding current (I H ) shortly after t2. The holding current (I H ) from t2 through t5 eventually reduces the power dissipation, after which the PWM voltage 65 is used to maintain the pinion 33 in the engaged state without overheating the pinion solenoid 21. Figure 1

[0037] As described above, reference is made to the portion of the motor voltage traces 64A marked 64B. Figure 1 ​​The pinion solenoid device 21 can be supplied with a PWM voltage by the controller 50 at a level that enables the pinion 33 to softly mesh with the flywheel 32 during the automatic stop condition of the engine 20. The on duration and motion of the starter motor 18 during the automatic stop phase can be controlled by applying a PWM voltage 64A to complete the pinion 33 full seating on the gear system 11 shown and to propel the engine to the desired crank angle. The delivery of the PWM voltage 64A can be achieved by applying the required PWM signal as a motor command signal 44 to the motor drive circuit 18D. During the restart of the engine 20, since the pinion 33 is fully seated with respect to the gear system 11, the motor solenoid device 16 is controlled to deliver the maximum power shown by the voltage trace 64 to the starter motor 18 to restart with minimal delay. Once the engine 20 is fully restarted, the controller 50 terminates the engine start signal at approximately t5 shown by the bit flag 62, while the pinion solenoid device 21 is de-energized. The controller 50 also terminates the motor solenoid control signal 17 when the motor speed reaches a predetermined value or when the engine start signal is terminated, whichever occurs first. The starter motor 18 is then turned off. The pinion solenoid coil current (trace 66) thereafter decays to zero. Figure 2

[0038] Reference is made to Figure 3 , a method 100 according to an exemplary embodiment begins at step 102, where Figure 1 the engine 20 is in an on / running condition. With the engine 20 running, the method 100 continues to step 104.

[0039] Step 104 includes determining whether the engine 20 has automatic stop enabled. For example, the controller 50 can determine through its internal logic whether the running conditions require stopping the engine 20, for example, when the vehicle of the powertrain 10 is at a red light or idling. Step 104 is repeated until the controller 50 decides to enable automatic stop, at which time the controller 50 continues to perform step 106. Figure 1

[0040] Step 106 includes comparing the engine speed (N 20 ) to a calibrated threshold speed (N1). When the engine speed is less than the calibrated threshold speed, i.e., N 20 <N1, the method 100 continues to step 108. Otherwise, the controller 50 repeats step 104.

[0041] In step 108, when the engine speed is less than the calibrated threshold speed of step 106, the controller 50 energizes the pinion solenoid device 21, as shown by the bit flag 63. The method 100 then continues to step 110. Figure 2 In step 110, the controller 50 energizes the motor solenoid device 16, as shown by the bit flag 62. The method 100 then continues to step 112.​​​

[0042] In step 110, the controller 50 commands the solenoid current I of the pinion solenoid device 21. C Reaching peak current level I P , that is I C =I P ,like Figure 2 The trace is shown in 66. In response to... Figure 1 The pinion solenoid control signal 56 can obtain this current. Then method 100 continues to step 112.

[0043] Step 112 includes activating the counter (T) of the controller 50 and waiting for a calibration delay duration (T1), where T1 is a predetermined duration suitable for allowing the pinion 33 to overcome friction and begin to move, with the ultimate goal of achieving contact between the pinion 33 and the flywheel 32, i.e., achieving a pre-engaged state. When T>T1, method 100 continues from step 112 to step 114.

[0044] In step 114, the controller 50 then controls the current I of the pinion solenoid device 21. C Set to a lower holding current level I H , that is I C =I H ,like Figure 2 The t2 of the middle trace 66 is shown. In some applications, the holding current (I) H It may be significantly lower than the peak current (I). P For example, in an exemplary auxiliary voltage embodiment, the peak current (I) P The current required for holding (I) can be as high as approximately 15-20A, while the holding current required for this embodiment is... H It can be as low as about 3-4A, or about the peak current (I). P The current is reduced to 20% of the value of the flywheel 32, where the term "about" used to describe this particular embodiment means within ±10%. Whenever the pinion 33 is fully engaged with the flywheel 32, the reduced current ensures low power consumption in the internal coil of the pinion solenoid device 21. Method 100 then proceeds to step 116.

[0045] Step 116 includes checking whether the engine has stopped, i.e., the engine speed (N). 20 Is it equal to 0? When the engine speed is less than the calibration threshold speed, i.e., N 20 =0, method 100 continues to step 118. Otherwise, controller 50 repeats step 116.

[0046] Step 118 includes making Figure 1The starter motor 18 shown is capable of rotating the engine crankshaft 31 by a predetermined crank angle, which is suitable for fully and smoothly engaging the gear system 11, pinion 33, and flywheel 32. Therefore, steps 108-114 translate the pinion 33 to... Figure 1 The position shown in 33A. Furthermore, a predetermined crank angle is selected to position the engine crank angle in a position where the time required to restart the engine at the start of the next engine start event is reduced. As a non-limiting example, the predetermined crank angle of the V8 engine can be in the range of 68 degrees to 88 degrees BTDC before top dead center (BTDC), preferably about 78 degrees BTDC. In an exemplary embodiment, as... Figure 2 As shown in voltage trace 64A, through Figure 1 The motor drive circuit 18D shown provides PWM drive to the starter motor 18 to realize the movement of the starter motor 18 in step 118, and at the same time provides the PWM signal as the motor command signal 44. Then method 100 continues to step 116.

[0047] Step 120 includes determining whether automatic start is enabled for engine 20. When automatic start is enabled, method 100 continues to step 122, repeating step 120 until it is determined that automatic start is enabled.

[0048] Step 122 includes passing through Figure 1 The motor solenoid control signal 17 commands the start motor 18 to crank the engine 20 to the threshold starting speed. At this point, fuel can be added to the engine and ignited to maintain operation. Step 122 may include commands. Figure 1 Motor torque (arrow T) M Adjust it to a level sufficient to rotate crankshaft 31. Then method 100 continues to step 124.

[0049] In step 124, the controller 50 determines whether the automatic start event has been completed when the engine speed (N) 20 If the engine speed exceeds a threshold speed, for example, at an idle speed of 600 RPM for a predetermined period of, for example, 200 ms, it indicates that automatic start-up has been completed. When engine 20 has been successfully started, method 100 continues to step 126.

[0050] Step 126 includes controlling Figure 1 The motor solenoid control signal 17 is used to remove the power supply voltage to the starter motor 18. Step 126 also includes using... Figure 1 The pinion solenoid control signal 56 disengages the pinion 33. In response to a corresponding control signal from the controller 50, the pinion solenoid device 21 translates the pinion 33 to disengage from the gear system 11 and the flywheel 32. Method 100 then continues to step 128.

[0051] In step 128, the restart is complete, and the method 100 returns to step 102 for a subsequent automatic stop event.

[0052] Accordingly, in Figure 1 In the context of the example powertrain system 10 shown, the method 100 can be advantageously utilized to improve the NVH performance of an engine start / stop system using the example starter motor 18 described herein, particularly in single-pinion driven solenoid systems powered via a low voltage power network by PWM signals and / or when an operator terminates an automatic stop procedure of the engine 20 prior to the engine 20 being completely stopped. Unlike Figure 1 Alternative functional partitioning of the architecture shown is also within the scope of the present disclosure. For example, it is conceivable that the PWM drive circuits 18D and 21D for the motor 18 and pinion solenoid device 21 can be integrated into the starter motor 18 and use appropriate commands to pre-engage the pinion 33 and control the rotation of the starter motor 18 via the CAN bus 35 or other communication channel, or through discrete signals between the controller 50 and the starter motor 18. Alternatively, the PWM drive circuits 18D and 21D for the motor 18 and pinion solenoid device 21 can be integrated into the controller 50, or into a battery fuse distribution unit (not shown). Such benefits and other possible benefits will be apparent to those of ordinary skill in the art in view of the present disclosure.

[0053] While some preferred modes and other embodiments have been described in detail, various alternative designs and embodiments exist for practicing the present teachings defined in the following claims. Persons of ordinary skill in the art will recognize that modifications can be made to the disclosed embodiments and other variations embodied herein can be employed without departing from the spirit of the present disclosure. The detailed description and accompanying drawings are supportive and descriptive of the present teachings, but the scope of the present teachings should be defined by the claims and not by the description of the preferred mode.

[0054] The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.

Claims

1. An electric starting system for an internal combustion engine, the internal combustion engine having a flywheel with a flywheel gear connected to an engine crankshaft, the electric starting system comprising: Small gear; A pinion solenoid device connected to the pinion; A starter motor is selectively connected to the flywheel of the engine via the pinion gear; and A controller, which communicates with the pinion solenoid device and the starter motor, is configured to: In response to the engine automatic stop signal: The command to shut down the engine; Determine the engine speed after the engine is shut down; In response to the engine speed being less than a first threshold speed, a command control current is transmitted to the pinion solenoid device at a peak current level, thereby converting the pinion into contact with the flywheel and the motor; In response to the engine speed being less than the second threshold speed, a command is given to excite the starter motor with pulse width modulation (PWM) to make the starter motor rotate, thereby causing the pinion to fully mesh with the flywheel and causing the engine crankshaft to rotate to a predetermined crank angle; When the engine crankshaft reaches the predetermined crank angle, the PWM excitation to the starter motor is stopped. After the pinion is fully engaged with the flywheel, a pulse width modulation (PWM) pinion control signal is transmitted at different voltages to transmit the control current to the pinion solenoid device at a fluctuating holding current level, wherein the holding current level is a non-zero value that is less than the peak current level. as well as In response to the engine automatic start signal: The command transmits the motor torque from the starter motor to the flywheel through the pinion, while maintaining the control current at the holding current level for a period of time sufficient to start the engine; The electric starting system also includes: Two independently controllable devices are used to supply current to the starter motor; One of the two independently controllable devices used to supply current to the starter motor includes a motor solenoid, while the other of the two independently controllable devices used to supply current to the starter motor includes a semiconductor switching device.

2. The electric starting system of claim 1, wherein the semiconductor switching device provides pulse width modulation (PWM) excitation to the starting motor.

3. The electric start system of claim 1, wherein an excitation is provided to the starter motor by a motor solenoid to transmit motor torque from the starter motor to the flywheel via the pinion, while the control current is maintained at the holding current level for a period of time sufficient to start the engine.

4. The electric starting system according to claim 1, wherein the pinion solenoid device and the starter motor are powered by an auxiliary voltage bus with a nominal voltage level of 15V or lower.

5. A method for controlling an electric starting system of an internal combustion engine, the internal combustion engine having a flywheel connected to an engine crankshaft, the method comprising: In response to an automatic engine stop signal, the engine is commanded to shut down; The controller determines when the engine speed is less than a first threshold speed. In response to the engine speed being less than the first threshold speed, a command is sent through the controller to transmit a control current at a peak current level to the pinion solenoid device, thereby converting the pinion connected to the pinion solenoid device into contact with the flywheel; In response to the engine speed being less than a second threshold speed, a command is given to start the motor to rotate, thereby causing the pinion to fully mesh with the flywheel and causing the engine crankshaft to rotate to a predetermined crank angle; After the pinion is fully engaged with the flywheel, a pulse width modulation (PWM) pinion control signal is transmitted at different voltages to transmit the control current to the pinion solenoid device at a fluctuating holding current level, wherein the holding current level is a non-zero value that is less than the peak current level. as well as In response to the engine automatic start signal, the controller commands the motor torque to be transmitted from the starter motor to the flywheel through the pinion, while the control current is maintained at the holding current level. The controller maintains the motor torque for a period of time sufficient to start the engine. The electric starting system includes two independently controllable devices for supplying current to the starter motor; One of the two independently controllable devices used to supply current to the starter motor includes a motor solenoid, while the other of the two independently controllable devices used to supply current to the starter motor includes a semiconductor switching device.

6. The method of claim 5, wherein the semiconductor switching device provides pulse width modulation (PWM) excitation to the starter motor.

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