ENGINE CONTROL APPARATUS

The present invention relates to an engine control apparatus for a vehicle equipped with an idling stop function, the apparatus preventing an engine startup failure and the occurrence of a failure of an engine starting device.

Patent Document 1 describes an engine automatic stop and restart device for use with an idling stop-capable vehicle that restarts using a starter, the device having a starter pinion gear engaged with an engine ring gear beforehand to shorten the time required to restart the engine from an idling stop state.

Patent Document 2 describes an engine starting device which, as a measure to reduce noise upon engine startup, causes the pinion gear and the ring gear to be engaged gently with each other while the engine is being stopped before getting started.

Vehicles equipped with the techniques of Patent Document 1 or 2 have the pinion gear and the ring gear kept engaged with each other when stopped. When restarted after being inactive for an extended period of time especially in cold regions, such vehicles may fail to get the pinion gear and the ring gear disengaged from each other due to freezing, which can result in a failure.

As a measure to avoid such an eventuality, Patent Document 3 describes a technique which, when the ignition system of the vehicle is turned off, disengages the pinion gear from the ring gear using a pinion drive means for causing the pinion gear to slide over the ring gear along an output rotation shaft, thereby preventing a failure stemming from the pinion gear being stuck with the ring gear at the next restart.

Patent Document 1: Japanese Patent 4214401

Patent Document 2: JP-2000-45920-A

Patent Document 3: JP-2006-342719-A

However, the problem is that if the engine stops with the pinion gear and the ring gear engaged with each other generating frictional force therebetween, it can be difficult using the technique of Patent Document 3 to actuate the pinion drive means to disengage these gears unfailingly against the frictional force while the ignition system of the vehicle is being turned off.

In solving the aforementioned problem and according to the present invention, there is provided an engine control apparatus comprising a ring gear for transmitting torque to an engine, a starting device for starting the engine, a pinion gear supported on an output rotation shaft of a starter motor of the starting device, and a pinion gear drive means for sliding the pinion gear on the output rotation shaft, the engine control apparatus being equipped with an idling stop function to stop the engine during engine idling, the engine control apparatus further performing control to engage the ring gear and the pinion gear with each other in an idling stop state. When the ring gear and the pinion gear are to be disengaged from each other, the pinion gear drive means actuates the pinion gear to disengage from the ring gear while the starter motor of the starting device is rotated simultaneously, thereby releasing the engagement.

When the ring gear and the pinion gear are to be disengaged from each other, the engine control apparatus of the present invention causes the pinion gear drive means to actuate the pinion gear to disengage from the ring gear while rotating the starter motor of the starting device simultaneously, thus releasing the engagement.

This patent application incorporates the content of the description and/or the drawings of Japanese Patent Application No. 2011-181605 to which this patent application claims priority.

According to the present invention, the pinion gear and the ring gear are disengaged unfailingly from each other at operation stop, which prevents these gears from being engaged with each other for an extended period of time. This in turn prevents such eventualities as the pinion gear and the ring gear being stuck with each other due to freezing or rust thereby hampering the engine from getting started; a stuck pinion gear overloading the starter motor resulting in a failure; and a helical spline portion of the pinion gear being exposed for an extended time period to gather rust and dust causing the pinion gear to return defectively.

FIG. 1 schematically depicts a functional structure of a system to which the engine control apparatus of the present invention is applied. The engine may be a four-cylinder engine for example. Each cylinder of the engine is furnished with an injector 110 and a spark ignition device 109. The injectors 110 and spark ignition device 109 of the cylinders are controlled by an ECU (engine control unit) 103.

The engine has the spark ignition device 109 igniting a mixture of air with fuel injected by the injectors 110 to cause combustion. The combustion pushes down pistons 112 to rotate a crank shaft 100 connected thereto and thereby generates power.

The engine is equipped with a crank angle sensor 102 and a cam angle sensor 107, the crank angle sensor 102 detecting rotational position information on the crank shaft 108, the cam angle sensor 107 detecting rotational position information on a cam shaft 111. The output of these sensors is input to the ECU 103. The ECU 103 discriminates cylinders and optimizes the injection or spark ignition timings based on signals from the crank angle sensor 102 or cam angle sensor 107.

A starter 101 is further used to start the engine. The starter 101 is made up of a starter motor 101a, a magnetic switch 101b, a shift lever 101c, a pinion clutch 101d, and a pinion gear 101e. When the driver turns on the starter switch 113, the magnetic switch 101b is energized. Energizing the magnetic switch 101b actuates the shift lever 101c to push the pinion gear 101e onto the side of the ring gear.

Also, turning on the starter switch 113 energizes and rotates the starter motor 101a that in turn rotates the pinion gear 101e connected to the same shaft as that of the motor. When pushed onto the side of the ring gear 106 while rotating, the pinion gear 101e engages with the ring gear 106. This mechanism allows the crank shaft 108 to rotate and move the pistons 112 up and down, thereby starting the engine.

On the other hand, when the engine is restarted from an idling stop state, the ECU 103 performs control to energize a pinion relay 105 and a starter motor relay 104. This structure allows the engine to be started in the same manner as when the driver turns on the starter switch 113.

While the engine is still running immediately before idling stop, the ECU 103 may also energize the pinion relay 105 causing the magnetic switch 101b to be energized and the shift lever 101c to be operated. This structure allows the pinion gear 101e and ring gear 106 to be engaged with each other and thereby contributes to shortening the time required to restart the engine next time.

FIG. 2 depicts a flowchart of steps in which the engine control apparatus as the first embodiment of the present invention operates.

In step S201, it is determined whether idling stop permission conditions are met. If such conditions are determined to be met, step S202 is reached.

In step S202, it is determined whether a request to release the engagement is made. The engagement release request is made when an end of the operation is detected as a result of the combination of the cab seat door being closed or not, cab seat load sensor status, ignition switch status and the like. If the engagement release request is determined to be made, step S203 is reached.

In step S203, it is determined whether the engine is being stopped. If the engine is determined to be in the stopped state, step S204 is reached. If the engine is not stopped (i.e., if the engine is rotating), then step S207 is reached.

In step S204, it is determined whether the pinion relay is on. If engagement holding control is in effect, the pinion relay is turned on. In this case, step S205 is reached and the pinion relay is turned off in response to a command from the ECU. If engagement holding control is not in effect, the pinion relay is turned off. In this case, step S204 is followed by step S206.

With the pinion relay turned off, the pinion gear loses the support of the shift lever and moves to disengage from the ring gear by means of spring force. However, the metal-to-metal frictional force between the pinion gear and the ring gear keeps the pinion gear engaged with the ring gear.

In step S206, a command from the ECU turns on the starter motor relay. This causes the pinion gear 101e to rotate. At this point, with the support of the shift lever lost in step S204, the pinion gear 101e rotates to reduce the metal-to-metal frictional force between the pinion gear and the ring gear and thereby releases the engagement therebetween.

In step S207, a command from the ECU turns off the pinion relay 101e. With the pinion relay turned off, the pinion gear 101e loses the support of the shift lever and moves to disengage from the ring gear by means of spring force, thereby releasing the engagement.

FIG. 3 depicts a timing chart of typical timings at which the engine control apparatus as the first embodiment operates (as shown in the flowchart of FIG. 2).

At time T251, the idling stop permission conditions are met, so that fuel to the engine is cut and the engine revolutions begin to drop.

At time T252, the pinion relay is turned on when the engine rotating speed drops below a predetermined rotating speed. This triggers control to engage the pinion gear 101e with the ring gear 106 so as to shorten the time to restart.

At time T253, the engagement release request is made to turn off the pinion relay. With the pinion relay turned off, the pinion gear 101e loses the support of the shift lever 101c, before the starter motor relay 104 is turned on for a short time to rotate the pinion gear 101e. This releases the engagement between the pinion gear 101e and the ring gear 106. In this manner, the pinion gear 101e and the ring gear 106 are disengaged unfailingly from each other by rotating the starter motor at the time of disengagement.

When the starter motor 101a of the starting device is to be rotated to release the above-mentioned engagement, the starter motor may be rotated with an amount of power less than that for rotating the starter motor 101a normally at engine start time. This saves energy and helps minimize a drop in battery voltage.

FIG. 4 depicts a flowchart of steps in which the engine control apparatus as the second embodiment of the present invention operates.

In step S301, it is determined whether the idling stop permission conditions are met. If the conditions are determined to be met, step S302 is reached.

In step S302, it is determined whether a request to release the engagement is made. The engagement release request is made when an end of the operation is detected as a result of the combination of the cab seat door getting closed or not, cab seat load sensor status, ignition switch status and the like. If the engagement release request is determined to be made, step S303 is reached.

In step S303, it is determined whether the engine is being stopped. If the engine is determined to be in the stopped state, step S304 is reached. If the engine is not stopped (i.e., if the engine is rotating), then step S308 is reached.

In step S304, it is determined whether the pinion relay is on. If engagement holding control is not in effect, the pinion relay is turned off. In this case, step S306 is reached. On the other hand, if engagement holding control is in effect, the pinion relay is turned on. In this case, step S305 is reached and the pinion relay is turned off in response to a command from the ECU. With the pinion relay turned off, the pinion gear 101e loses the support of the shift lever 101c and moves to disengage from the ring gear 106 by means of spring force. However, the metal-to-metal frictional force between the pinion gear 101e and the ring gear 106 keeps these gears engaged.

In step S306, a command from the ECU causes the injector 110 to inject fuel.

In step S307, the spark ignition device 109 of the cylinder into which fuel was injected in step S306 ignites sparks therein. The sparks cause combustion of the air-fuel mixture in the cylinder of interest, generating torque that rotates the ring gear 106. At this point, with the support of the shift lever lost, rotating the ring gear 106 lowers the metal-to-metal frictional force between the pinion gear 101e and the ring gear 106 and thereby releases the engagement therebetween.

In step S308, a command from the ECU turns off the pinion relay. With the pinion relay turned off, the pinion gear loses the support of the shift lever and is disengaged from the ring gear by means of spring force. This releases the engagement.

FIG. 5 depicts a timing chart of typical timings at which the engine control apparatus as the second embodiment operates (as shown in the flowchart of FIG. 4).

At time T351, the idling stop permission conditions are met, so that fuel to the engine is cut and the engine revolutions begin to drop.

At time T352, the pinion relay 105 is turned on when the engine rotating speed drops below a predetermined rotating speed. This triggers control to engage the pinion gear 101e with the ring gear 106 so as to shorten the time to restart.

At time T353, the engagement release request is made to turn off the pinion relay. With the pinion relay turned off, the pinion gear 101e loses the support of the shift lever 101c. At the same time, the injector 110 injects fuel into the cylinder in the compression stroke.

At time T354, the fuel injected at time T353 spreads throughout the cylinder. At this timing, the spark ignition device 109 ignites the air-fuel mixture in the fuel-injected cylinder. As a result, the ring gear 106 rotates to disengage from the pinion gear 101e. In this manner, the pinion gear 101e and the ring gear 106 are disengaged unfailingly from each other by igniting the air-fuel mixture in the fuel-injected cylinder at the time of disengagement.

In each of the above-described embodiments, the engine control apparatus may be furnished with a function to maintain at a predetermined level or higher the brake pressure of the braking device of the vehicle incorporating the apparatus, when the pinion gear 101e and the ring gear 106 are disengaged from each other. This function will contribute to improving safety by preventing unpredictable movement of the vehicle, among others. All publications, patents, and patent applications cited in this description are hereby incorporated by reference.

• 101 Starter
• 101a Starter motor
• 101b Magnetic switch
• 101c Shift lever
• 101d Pinion clutch
• 101e Pinion gear
• 102 Crank angle sensor
• 103 ECU (engine control unit)
• 104 Starter motor relay
• 105 Pinion relay
• 106 Ring gear
• 107 Cam angle sensor
• 108 Crank shaft
• 109 Spark ignition device
• 110 Injector
• 111 Cam shaft
• 112 Piston
• 113 Starter switch
• 114 Battery
• T251 Timing at which idling stop permission conditions are met
• T252 Timing at which engagement holding control is started
• T253 Timing at which engagement release request is made
• T351 Timing at which idling stop permission conditions are met
• T352 Timing at which engagement holding control is started
• T353 Timing at which engagement release request is made
• T354 Spark ignition timing