Engine automatic-stop/restart system

• US 8,419,592 B2
• Filed: 10/21/2011
• Issued: 04/16/2013
• Est. Priority Date: 05/17/2011
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Fujiwara, Michitaka
• Primary Examiner(s): YOUNG, EDWIN
• Application Number:
  US13/278,420
• Publication Number:
  US 20120295759A1
• Time in Patent Office: 543 Days
• Field of Search: 477/167, 477/178, 477/180, 477/181
• US Class Current: 477/167
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 2030/1809 Without torque flow between driveshaft and engine, e.g. with clutch disengaged or transmission in neutral
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/0685 Engine crank angle
• CPC Class Codes: B60W 2710/023 Clutch engagement rate
• CPC Class Codes: B60W 2710/0627 Fuel flow rate
• CPC Class Codes: B60W 30/18018 Start-stop drive, e.g. in a traffic jam
• CPC Class Codes: B60W 30/18072 Coasting
• CPC Class Codes: F02N 11/0844 with means for restarting the engine directly after an engine stop request, e.g. caused by change of driver mind
• CPC Class Codes: F02N 11/0855 during engine shutdown or after engine stop before start command, e.g. pre-engagement of pinion
• CPC Class Codes: F02N 2200/022 Engine speed
• CPC Class Codes: F02N 2200/041 Starter speed
• CPC Class Codes: F02N 2200/0802 Transmission state, e.g. gear ratio or neutral state
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An engine automatic-stop/restart system resumes injection of fuel when an engine restart condition is satisfied, and energizes the starter motor when, after injection of the fuel has resumed, starting of the engine is not completed. The system can also control the coupling degree of a forward clutch under certain conditions, and energize a solenoid to engage a starter pinion with a crankshaft ring gear when their relative speeds are close to each other. The system then releases the forward clutch after the pinion and the ring gear have engaged.

Claims

1. An engine automatic-stop/restart system that automatically stops an engine when an automatic stopping condition is satisfied while a vehicle travels and then restarts the engine when a restarting condition is satisfied, the engine automatic-stop/restart system comprising:

a starter motor that is energized to rotate;

a pinion gear provided on the rotor shaft of the starter motor;

a ring gear provided on the crankshaft of the engine;

a solenoid that is energized to be biased;

a plunger that pushes out the pinion gear in the axis direction thereof when the solenoid is energized, so that the pinion gear engages with the ring gear;

a crank angle sensor that detects a crank angle of the engine and outputs a crank angle signal;

a fuel injection device that injects fuel into the engine;

a forward clutch that transmits torque produced by the engine to a transmission;

a first control system that connects a power source with the starter motor in response to a first drive signal so as to energize the starter motor and connects the power source with the solenoid in response to a second drive signal so as to energize the solenoid;

a second control system that controls the fuel injection device to make the fuel injection device inject fuel into the engine when the engine that has automatically stopped is restarted, that outputs the first drive signal to the first control system when the rotation speed of the engine is lower than a predetermined value, and that outputs the second drive signal to the first control system so as to energize the solenoid when the absolute value of a rotation-speed difference between an engine rotation speed calculated based on the cycle of the detected crank angle signal and the rotation speed of the pinion gear becomes smaller than a rotation speed difference threshold value at which the pinion gear and the ring gear can engage with each other; and

a third control system that is configured in such a way as to control the coupling degree of the forward clutch so that the rotation speed of the engine can be controlled, when the engine, which cannot autonomously rotate only with fuel supply, is restarted and the rotation speed of an input shaft of the transmission is the same as or higher than the engine rotation speed, and that releases the forward clutch after the pinion gear and the ring gear have engaged with each other.

2. The engine automatic-stop/restart system according to claim 1, wherein when the rotation speed of the input shaft of the transmission is the same as or higher than the engine rotation speed and is lower than a predetermined value, the third control system controls the rotation speed of the engine by making the forward clutch to be coupled so as to transmit reverse torque from the vehicle axle to the engine.

3. An engine automatic-stop/restart system provided with a control system that automatically stops an engine when an automatic stopping condition is satisfied while a vehicle travels and then restarts the engine when a restarting condition is satisfied after the engine has automatically stopped, the engine automatic-stop/restart system comprising:

a starter motor that is energized to rotate;

a pinion gear provided on the rotor shaft of the starter motor;

a ring gear provided on the crankshaft of the engine;

a solenoid that is energized to be biased;

a plunger that pushes out the pinion gear in the axis direction thereof when the solenoid is energized, so that the pinion gear engages with the ring gear;

a crank angle sensor that detects a crank angle of the engine and outputs a crank angle signal;

a fuel injection device that injects fuel into the engine; and

a forward clutch that transmits torque produced by the engine to a transmission,

wherein the control system makes the fuel injection device stop injection of the fuel so as to stop the engine, when the automatic stopping condition for the engine is satisfied,

makes the fuel injection device resume injection of the fuel, when there is satisfied the restart condition for the engine that has stopped,

energizes the starter motor when after injection of the fuel has resumed, starting of the engine is not completed,

controls the coupling degree of the forward clutch so as to control the rotation speed of the engine, when the engine cannot autonomously rotate only with fuel supply and the rotation speed of an input shaft of the transmission is the same as or higher than the engine rotation speed and is lower than a predetermined value,

energizes the solenoid when the absolute value of a rotation-speed difference between an engine rotation speed calculated based on the cycle of the detected crank angle signal and the rotation speed of the pinion gear becomes smaller than a rotation speed difference threshold value at which the pinion gear and the ring gear can engage with each other, and

releases the forward clutch after the pinion gear and the ring gear have engaged with each other.