JP5926907B2 - Engine stop control device - Google Patents

Description

  The present invention relates to an engine stop control device, and more particularly to a stop control device that suppresses local wear of a ring gear caused by meshing with a starter pinion at start-up by dispersing crank positions after engine stop.

  In a general vehicle, the engine is started by a starter, and the starter is disposed on one side of a ring gear fixed to the rear end of the crankshaft of the engine. According to the driver's key operation, the pinion gear of the starter protrudes and meshes with the ring gear by excitation of the solenoid, and the crankshaft is rotationally driven together with the ring gear through the pinion gear by the driving force of the motor, and the engine is cranked and started. . The engine at the time of stoppage is stopped by receiving a reaction force generated in the vicinity of the compression top dead center of each cylinder while inertially rotating, so as shown in FIG. 5, the crank position of the engine after the stop (hereinafter referred to as stop crank) In particular, the frequency of stopping at the crank position corresponding to the compression top dead center of each cylinder becomes very high. For this reason, in many engine starts, the pinion gear of the starter meshes with a specific part of the ring gear and rotation driving is started, and wear starts locally at the meshed part, causing a start failure early. was there.

  In particular, in an idle stop start vehicle that automatically stops and starts the engine, such as waiting for a signal that has begun to spread in recent years, the frequency of engine start increases dramatically, so the local wear of the ring gear is more serious become. For this reason, drastic countermeasures are desired, and for example, the technique of Patent Document 1 using a power tard is proposed. As is well known, a power tard is a piston that is forced to open the exhaust valve of each cylinder temporarily just before compression top dead center to discharge compressed air from the cylinder, and the negative pressure generated in the cylinder in the subsequent expansion stroke. This is a system that prevents the descent and increases the engine braking force. Focusing on the fact that the action of such a power tard leads to a substantial reduction in compression work, and in turn, a reduction in the compression reaction force, the technology of Patent Document 1 distributes the stop crank position by executing the power tard when the engine is stopped. I am trying.

JP 2001-152822 A

In order to verify the operational effects of the technique of Patent Document 1, the present inventor conducted a test to determine the occurrence frequency for each stop crank position by executing a power tard when the engine is stopped. However, the test results obtained are almost the same as the case where the power tard shown in FIG. 5 is not executed. As a result, the technique of Patent Document 1 cannot disperse the stop crank position and suppress local wear of the ring gear. I had to say that it was not effective as a countermeasure.
The present invention has been made to solve such problems, and the object of the present invention is to disperse the crank position when the engine is stopped and localize the ring gear due to meshing with the starter pinion at the start. Another object of the present invention is to provide an engine stop control device that can suppress excessive wear.

  In order to achieve the above object, the invention of claim 1 is directed to stop the engine mounted on the vehicle and to stop the fuel injection to the engine based on the stop instruction means for instructing the engine to stop and the engine stop instruction by the stop instruction means. The engine stop control means, the forced exhaust valve opening mechanism that temporarily forcibly opens the exhaust valve near the compression top dead center of the engine cylinder, and the exhaust valve forced opening mechanism that eliminates the delay in operation, An operation start determining means for determining whether or not the valve opening has been started, and the engine stop control means starts the operation of the exhaust forced valve opening mechanism when the engine stop instruction is given by the stop instructing means. It waits until the start determination means makes a start determination for forced opening of the exhaust valve, and when the start determination is made, the engine is stopped by stopping fuel injection.

According to a second aspect of the present invention, in the first aspect, when the operation start determining means has elapsed a preset delay time based on an operation delay of the exhaust forced valve opening mechanism from the start of operation of the exhaust forced valve opening mechanism, This determines whether to start the valve forcibly.
According to a third aspect of the present invention, there is provided the intake throttle valve according to the first or second aspect, wherein the intake throttle valve for restricting the intake air of the engine by closing the valve is provided. The valve is closed.
According to a fourth aspect of the present invention, in the first to third aspects, the engine temperature detection means for detecting the temperature of the engine is provided, and the engine stop control means is a first engine temperature detected by the engine temperature detection means. The operation of the forced exhaust valve opening mechanism is prohibited when it is less than the judgment value.

According to a fifth aspect of the present invention, in the first to fourth aspects, the engine is mounted on the vehicle as a driving power source, the engine is stopped when a preset engine stop condition is satisfied, and a preset engine start condition is satisfied. It is equipped with an idle stop start control means that sometimes starts the engine.
According to a sixth aspect of the present invention, in the fourth aspect, the engine is mounted on the vehicle as a driving power source, the engine is stopped when a preset engine stop condition is satisfied, and the engine is set when a preset engine start condition is satisfied. When the engine temperature detected by the engine temperature detecting means is lower than the second determination value preset on the lower temperature side than the first determination value, The engine stop based on the engine stop condition is prohibited.

As described above, according to the engine stop control device of the invention of claim 1, when the engine stop instruction is issued by the stop instruction means, the operation of the exhaust forced valve opening mechanism is started by the engine stop control means, The system waits until the start determination of the forced opening of the exhaust valve is made by the operation start determination means, and when the start determination is made, the engine stop control means stops the fuel injection and stops the engine.
Therefore, when the fuel injection is stopped, the operation delay of the forced exhaust valve opening mechanism is already eliminated, and the exhaust valve is normally forced open. For this reason, the compression reaction force is reduced, and the engine that has started inertial rotation due to the cancellation of fuel injection smoothly stops its rotation speed without being subjected to an extreme reaction force at the compression top dead center, leading to the stop crank position. Is decentralized. Therefore, local wear of the ring gear at the time of starting the engine can be suppressed, and troubles such as poor starting can be prevented in advance.

According to the engine stop control device of the second aspect of the present invention, in addition to the first aspect, when the delay time preset based on the operation delay of the forced exhaust valve opening mechanism has elapsed, the forced opening of the exhaust valve is controlled. The start judgment was made. Therefore, it is possible to determine the timing at which forced valve opening is started without adding a new sensor or the like, that is, an appropriate fuel injection stop timing, and it is possible to carry out without increasing the manufacturing cost.
According to the engine stop control device of the third aspect of the present invention, in addition to the first or second aspect, the intake throttle valve is closed when the exhaust forced valve opening mechanism is started. Accordingly, since the intake air amount is reduced by closing the intake throttle valve and the substantial compression work in the cylinder is further reduced, the stop crank value can be further dispersed.
According to the engine stop control device of the fourth aspect of the invention, in addition to the first to third aspects, the operation of the forced exhaust valve opening mechanism is prohibited when the engine temperature is lower than the first determination value. For example, the hydraulic exhaust forced valve opening mechanism cannot be operated accurately due to the high viscosity of the hydraulic oil in the low temperature range, but the exhaust forced valve opening mechanism is prohibited from operating. Can be prevented.

According to the engine stop control device of the invention of claim 5, in addition to claims 1 to 4, an idle stop start control means for stopping the engine when the engine stop condition is satisfied and starting the engine when the engine start condition is satisfied. I was prepared to. Therefore, the frequency of engine start is dramatically increased, and local wear of the ring gear is apt to proceed inevitably, but this problem can be reliably solved.
According to the engine stop control device of the invention of claim 6, in addition to claim 4 , the engine stop is prohibited when the engine temperature is lower than the second determination value. When the engine is cold, the amount of fuel needs to be increased and sufficient purification performance cannot be obtained. However, since the engine can be stopped early, warm-up can be completed early, and these problems can be minimized.

1 is an overall configuration diagram showing a vehicle on which an engine stop control device of an embodiment is mounted. It is a flowchart which shows the ISS routine which ISS-ECU performs. It is a flowchart which shows the E / G stop routine which E / G-ECU performs. It is a test result which shows the generating frequency for every stop crank position by an embodiment. It is a test result which shows the generating frequency for every stop crank position by a prior art.

Hereinafter, an embodiment of an engine stop control device embodying the present invention will be described.
FIG. 1 is an overall configuration diagram showing a vehicle equipped with an engine stop control device of the present embodiment. As will be described later, the vehicle has an idle stop start function that automatically stops and starts the engine that is a driving power source when waiting for a signal, etc., and the stop control device performs a key-off operation (stop instruction) by a normal driver. In addition to when the engine is stopped by the means), it also functions when the engine is automatically stopped by the idle stop function (stop instruction means) to appropriately control the engine.
A transmission 4 is connected to the rear end of the crankshaft 1 a of the engine 1 mounted on the vehicle via a flywheel 2 and a clutch 3, and the transmission 4 is connected to a propeller shaft 5, a differential device 6, and a drive shaft 7. Are connected to the left and right drive wheels 8. Accordingly, the driving force of the engine 1 is cut off and not transmitted to the transmission 4 when the clutch 3 is disconnected, and is transmitted to the transmission 4 via the clutch 3 when the clutch 3 is connected. In response to this, the speed is changed and transmitted to the drive wheel 8 side.

The transmission 4 of the present embodiment is configured as a so-called parallel shaft type manual transmission, and the clutch 3 is also configured as a manual clutch. For this reason, at the time of shifting the transmission 4, the driver switches the transmission 4 to a desired gear stage by operating the shift lever while connecting and disconnecting the clutch 3 by operating the clutch pedal. However, the type of the transmission 4 is not limited to this, and may be configured as, for example, an automatic transmission that performs a shift operation and a clutch operation with an actuator. In addition, it is configured as a so-called dual clutch type automatic transmission that has two independent clutch and gear mechanisms, and performs preselection to switch the other system to the next gear stage in advance during power transmission through one system. Alternatively, it may be configured as a general torque converter type automatic transmission or CVT.
On the other hand, a fuel injection valve 10 is provided in each cylinder of the engine 1, and fuel is injected from the fuel injection valve 10 into each cylinder. The cylinders of the cylinders are connected to an intake manifold 12 via intake valves 11, and the upstream sides of the intake manifold 12 are gathered together and connected to an intake passage 13. An intake throttle valve 14 is provided in the intake passage 13 so that the intake air flowing through the intake passage 13 is restricted according to the opening of the intake throttle valve 14. Although not shown, the cylinders of the cylinders are connected to an exhaust manifold via exhaust valves 15, and the downstream sides of the exhaust manifolds are gathered together and connected to an exhaust passage provided with an exhaust purification device.

The intake air introduced into the intake passage 13 is guided to the intake manifold 12 while being restricted according to the opening degree of the intake throttle valve 14, distributed in the intake manifold 12, and when the intake valve 11 of each cylinder is opened. It flows into the cylinder. The fuel injected from the fuel injection valve 10 into the cylinder of each cylinder is ignited near the compression top dead center, and the piston is pushed down by the combustion pressure to generate engine torque. On the other hand, the exhaust gas after combustion is guided from the cylinder of each cylinder to the exhaust passage through the exhaust manifold when the exhaust valve 15 is opened, and is exhausted to the outside after the harmful components are purified by the exhaust purification device.
The exhaust valve 15 of each cylinder of the engine 1 is provided with an exhaust forced valve opening mechanism 17 of a power tard. Since the configuration of the exhaust forced valve opening mechanism 17 is disclosed in various documents and is not described in detail, for example, the one described in JP 2007-247628 A can be applied. The outline of the application example will be described. On the camshaft, a power-tard cam is attached to the exhaust cam of each cylinder, and the hydraulic piston is pressed by each power-tard cam immediately before the compression top dead center of each cylinder. The hydraulic piston is connected to a slave piston 16 disposed immediately above the exhaust valve 15 via a hydraulic pipe, and the slave piston 16 presses the exhaust valve 15 from above to temporarily forcibly open the valve. The compressed air can be discharged. A solenoid 18 is interposed in the hydraulic piping, and the hydraulic pressure generated by the hydraulic piston is transmitted or cut off to the slave piston 16 side via the hydraulic piping in response to the solenoid 18 being turned on / off, and the exhaust valve 15 is forced accordingly. The valve opening is executed or stopped.

When the power tard is executed at the time of vehicle deceleration due to the accelerator off, the exhaust valve 15 immediately before the compression top dead center is forced open to discharge the compressed air in the cylinder, and a force that prevents the piston from descending is generated in the subsequent expansion stroke. Increase the engine braking action. Thus, the original power tard operates in conjunction with the accelerator operation, and plays the role of reducing the driver's burden by reducing the frequency of the foot brake operation by increasing the engine braking action. In the present embodiment, the above power tard is also used when the engine is stopped, and details thereof will be described later.
The engine 1 is provided with a starter 19 for starting, and the starter 19 has the same configuration as a general one. That is, when starting the engine, the starter 19 projects the pinion gear 19a by the excitation of a built-in solenoid (not shown) and meshes with the ring gear 2a on the outer periphery of the flywheel 2, and via the pinion gear 19a by the driving force of the built-in motor. The engine 1 can be cranked by rotating the crankshaft 1 a together with the flywheel 2. Since the vehicle has the idle stop start function as described above, the cranking of the engine 1 by the starter 19 is automatically performed by the idle stop start function in addition to the engine start accompanying the key start operation by the normal driver. It is executed even when the engine is started.

On the other hand, an E / G-ECU (engine control unit) 21 for controlling the operating state of the engine 1 and an ISS-ECU (idle stop start control unit) 22 for controlling an idle stop start function are installed in the vehicle interior. ing. These E / G-ECU 21 and ISS-ECU 22 include an input / output device (not shown), a storage device (ROM, RAM, etc.) used for storing control programs and control maps, a central processing unit (CPU), a timer counter, etc. It is composed of
On the input side of the E / G-ECU 21, an accelerator sensor 23 for detecting the accelerator operation amount θacc, a rotation speed sensor 24 for detecting the rotation speed Ne of the engine 1, and a water temperature sensor 25 for detecting the cooling water temperature Tw of the engine 1 (engine Sensors such as temperature detection means) are connected, and on the output side of the E / G-ECU 21, there are provided a fuel injection valve 10 for each cylinder, a solenoid 18 for controlling the exhaust forced opening mechanism 17 of the power turret, and an intake throttle valve 14. Devices such as an actuator 26 for opening and closing and a starter 19 are connected.

Further, on the input side of the ISS-ECU 22, in addition to the accelerator sensor 23, the rotation speed sensor 24, and the water temperature sensor 25, a clutch sensor 27 that detects the connection / disconnection state of the clutch 3, and the gear position of the transmission 4 are detected. Sensors such as a gear position sensor 28, a vehicle speed sensor 29 for detecting the vehicle speed V, and an ISS switch 30 for instructing the validity / invalidity of the idle stop start function are connected. Further, an E / G-ECU 21 is connected to the output side of the ISS-ECU 22 so that a start command and a stop command for the engine 1 are output to the E / G-ECU 21.
Based on detection information input from various sensors, for example, the E / G-ECU 21 calculates a fuel injection amount and a fuel injection timing, and operates the engine 1 while driving and controlling the fuel injection valve 10 based on these calculated values. . Further, the ISS-ECU 22 executes idle stop start control for automatically stopping and starting the engine 1 by waiting for a signal or the like, and the control will be described below.

The ISS-ECU 22 executes the ISS routine shown in FIG. 2 at a predetermined control interval when the vehicle key is turned on and the ISS switch 30 is switched to the effective side of the idle stop start function.
First, it is determined whether or not the cooling water temperature Tw detected by the water temperature sensor 25 in step S2 is equal to or higher than a preset second determination value Tw2. When the engine is cold, an increase in fuel is required to stabilize the operation, and the catalyst of the exhaust purification device does not reach the activation temperature, so that sufficient purification performance cannot be obtained. Therefore, the engine operation in the cold state should be removed as early as possible to complete the warm-up, and for that purpose, it is desirable to prohibit the idle stop and continue the engine operation when the engine is cold. From such a viewpoint, the second determination value Tw2 is set as a temperature near the upper limit at which idle stop should be prohibited.
Accordingly, when the determination in step S2 is No (No), the routine is temporarily terminated because the idle stop should not be executed. Further, when the determination in step S2 is Yes (positive), it is determined that the idle stop should be executed, the process proceeds to step S4, and it is determined whether or not a preset engine stop condition is satisfied. The engine stop condition is considered to be satisfied when all the requirements described below are satisfied.
1) The accelerator operation amount θacc detected by the accelerator sensor 23 is zero.
2) The vehicle speed V detected by the vehicle speed sensor 29 is zero.
3) The clutch connection is detected by the clutch sensor 27.
4) Neutral is detected by the gear position sensor 28.
However, the engine stop condition is not limited to the above contents and can be arbitrarily changed. For example, it may be added that the brake is depressed.

When the determination in step S4 is No, the routine is temporarily terminated. When the determination is Yes, the routine proceeds to step S6 and an engine stop command is output to the E / G-ECU 21 (idle stop start control means). As will be described later, based on this stop command, the E / G-ECU 21 performs fuel cut (stops fuel injection) to stop the engine 1 (engine stop control means), and the ISS-ECU 22 sets in advance in step S8. It is determined whether or not the engine start condition is satisfied. The engine start condition is considered to be satisfied when all the requirements described below are satisfied.
5) The clutch disengagement is detected by the clutch sensor 27.
6) Neutral is detected by the gear position sensor 28.
While the determination in step S8 is No, the process waits. If the determination is Yes, the process proceeds to step S10 and an engine start command is output to the E / G-ECU 21 (idle stop start control means). Based on this start command, the engine 1 is started by the E / G-ECU 21 and the vehicle can start.

As described above, the engine stop or engine start is executed by the E / G-ECU 21 based on the engine stop command or the start command output from the ISS-ECU 22 at the time of idling stop start. Further, even when a key operation is manually performed by the driver, the engine is started at the start operation and the engine is stopped at the off operation.
When starting the engine, the pinion gear 19a of the starter 19 is meshed with the ring gear 2a and rotationally driven to crank the engine 1 and operate the fuel injection valve 10 to start fuel injection, but the pinion gear 19a identifies the ring gear 2a. There is a problem that local wear is generated by meshing with a portion. As a countermeasure, in the technique of Patent Document 1, power tard is executed when the engine is stopped. However, as described in [Problems to be Solved by the Invention], the stop crank position cannot be dispersed and the ring gear 2a is locally distributed. Unable to suppress excessive wear.
This fact means that the effect of reducing the compression reaction force of the engine 1 due to the power tard is not obtained when the engine is stopped. The inventor conducted a test for executing power tard when the engine was stopped, and verified the operating state of the exhaust forced valve opening mechanism 17 at this time. As a result, before the exhaust forced valve opening mechanism 17 starts substantial operation, more specifically, before the hydraulic pressure generated by the hydraulic piston is transmitted to the slave piston 16 and the exhaust valve 15 begins to be forced open. The engine 1 has been found to be caused by a phenomenon that stops after completing inertial rotation. Therefore, in this embodiment, measures are taken to delay the start of fuel cut with respect to the start of power tard when the engine is stopped, and the measures are described in detail below.

The E / G-ECU 21 executes the E / G stop routine shown in FIG. 3 at a predetermined control interval when the key of the vehicle is turned on, and the engine stop command or key by the idle stop is executed by the routine. The engine is stopped according to the off operation.
First, in step S22, it is determined whether or not there has been either an engine stop command from the ISS-ECU 22 or a vehicle key off operation. If the determination is No, the routine is temporarily terminated. As described above, when the engine stop command is input from the ISS-ECU 22 or when the driver who has finished traveling the vehicle turns off the key, the determination of Yes is made in step S22 and the process proceeds to step S24. . Even if the key is turned off, the E / G-ECU 21 continues the process until the engine 1 is stopped according to the routine.
In step S24, it is determined whether or not the coolant temperature Tw is equal to or higher than a preset first determination value Tw1. As will be described below, when the engine is stopped, the exhaust forced valve opening mechanism 17 of the power tard is operated, but the exhaust forced valve opening mechanism 17 that forcibly opens the exhaust valve 15 using hydraulic pressure is the viscosity of the hydraulic oil (engine oil). However, accurate operation cannot be expected at low temperatures. Therefore, the first determination value Tw1 is set as the temperature near the upper limit at which power tard should be prohibited. The first determination value Tw1 is set higher than the second determination value Tw2, which is the upper limit temperature at which the idling stop should be prohibited. As a result, the three temperature ranges are divided based on both determination values Tw1 and Tw2. Will be.

In the present embodiment, the temperature range of the engine 1 is divided using the coolant temperature Tw as an index, but the present invention is not limited to this and can be arbitrarily changed. For example, the engine oil temperature may be used as an index instead of the cooling water temperature Tw.
When the determination in step S24 is No, the process proceeds to step S26, and the fuel cut of the engine 1 is executed. Thereby, the fuel injection to each cylinder is stopped, and the engine 1 is stopped after inertial rotation.
When the determination in step S24 is Yes, the exhaust forced valve opening mechanism 17 is operated by turning on the power-tard solenoid 18 provided in each cylinder in step S28 (engine stop control means). In subsequent step S30, the intake throttle valve 14 is closed by the drive control of the actuator 26 (engine stop control means). Thereafter, the process proceeds to step S32, where it is determined whether or not a preset delay time Tdly has elapsed since the start of the operation of the forced exhaust valve opening mechanism 17, more specifically, from the time when the solenoid 18 is turned on. When the determination is No, the process stands by, and when the determination is Yes, the process proceeds to step S26 to execute fuel cut (engine stop control means).

まず、キーのオフ操作については、冷却水温Ｔwに関わらずエンジン１が停止され、冷却水温Ｔwが第１判定値Ｔw1未満のときには燃料カットのみが実行されるのに対し、第１判定値Ｔw1以上のときには燃料カットと共にパワータード及び吸気スロットル弁１４の閉制御が実行される。
また、アイドルストップについては、冷却水温Ｔwが第２判定値Ｔw2以上のときに限ってエンジン１が停止され、第２判定値Ｔw2未満ではエンジン１は停止されずに運転を継続する。そして、冷却水温Ｔwが第２判定値Ｔw2以上で且つ第１判定値Ｔw1未満のときには燃料カットのみが実行されるのに対し、第１判定値Ｔw1以上のときには燃料カットと共にパワータード及び吸気スロットル弁１４の閉制御が実行される。 The delay time Tdly is set in advance as a value obtained by adding a predetermined margin to the time corresponding to the operation delay of the exhaust forced valve opening mechanism 17. Specifically, the operation delay of the exhaust forced valve opening mechanism 17 is the time from when the solenoid 18 is turned on until the hydraulic pressure is actually transmitted from the hydraulic piston to the slave piston 16 and the exhaust valve 15 begins to be forced open. It corresponds to time. If the water temperature range is equal to or higher than the first judgment value Tw1, the oil temperature will rise sufficiently and there will be no large difference in the viscosity of the hydraulic oil, so the power delay can be derived as a single value, based on that The delay time Tdly can also be determined.
Based on the processing of the ISS-ECU 22 and the E / G-ECU 21 described above, stop control of the engine 1 is executed as shown in Table 1, and each case will be described in turn below. In the figure, the fuel cut is represented by “F / C”, the power tard is represented by “PT”, and the closing control of the intake throttle valve 14 is represented by “intake TH”.

First, regarding the key-off operation, the engine 1 is stopped regardless of the cooling water temperature Tw, and when the cooling water temperature Tw is lower than the first determination value Tw1, only the fuel cut is executed, whereas the first determination value Tw1 or more. In this case, the closing control of the power tard and the intake throttle valve 14 is executed together with the fuel cut.
As for the idle stop, the engine 1 is stopped only when the coolant temperature Tw is equal to or higher than the second determination value Tw2, and the engine 1 continues to operate without being stopped when it is less than the second determination value Tw2. When the coolant temperature Tw is equal to or higher than the second determination value Tw2 and lower than the first determination value Tw1, only the fuel cut is executed. Is closed.

That is, regardless of whether the engine 1 is stopped by the key-off operation or idling stop, if the coolant temperature Tw is equal to or higher than the first determination value Tw1, the power cut is executed together with the fuel cut. The process of steps S32 and S26 in FIG. 3 starts the operation of the exhaust forced valve opening mechanism 17, and the fuel cut is executed after the delay time Tdly has elapsed. The operation delay of the valve opening mechanism 17 is eliminated, and the exhaust valve 15 of each cylinder is normally forcibly opened. As a result of the forced opening of the exhaust valve 15 immediately before the compression top dead center, the compression reaction force of each cylinder is reduced. As a result, the engine 1 that has started inertial rotation due to the fuel cut is the compression top dead center of each cylinder. Thus, the rotational speed is smoothly reduced without being subjected to an extreme reaction force, resulting in stopping, and the stopping crank positions are dispersed. FIG. 4 shows a test result indicating the frequency of occurrence at each stop crank position at this time. As is clear from comparison with FIG. 5 showing the test result of the technique of Patent Document 1, the stop crank position is greatly dispersed. It can be seen that
Therefore, when the engine is started, the entire circumference of the ring gear 2a is used substantially uniformly for the engagement of the pinion gear 19a of the starter 19, and a starting failure due to the progress of local wear of the ring gear 2a can be prevented. This factor also contributes to the maintenance of the engine 1, and the maintenance cost can be reduced by extending the replacement interval of the flywheel 2.

In addition, by reducing the compression reaction force of each cylinder when the engine is stopped, the reaction force received by the engine 1 during inertial rotation fluctuates smoothly. As a result, there is another effect that the engine vibration at the time of stop can be reduced. can get.
In particular, in the vehicle having the idle stop start function as in the present embodiment, the frequency of engine start is remarkably high, and the problem of start failure and maintenance cost due to local wear of the ring gear 2a inevitably becomes more serious. However, since these problems can be surely solved, a greater effect can be realized.
In this embodiment, the delay time Tdly is set in advance based on the operation delay of the exhaust forced valve opening mechanism 17, and the fuel cut is executed based on the elapse of the delay time Tdly. For this reason, it is possible to determine the timing at which the forced opening of the exhaust valve 15 is started by eliminating the operation delay of the exhaust forced valve opening mechanism 17 without adding a new sensor, that is, the start timing of an appropriate fuel cut. It can be carried out without increasing the manufacturing cost.

In addition, in the present embodiment, closing control of the intake throttle valve 14 is used in combination when the power tard is executed. When the intake throttle valve 14 is closed, substantial compression work in the cylinder is further reduced as the intake air amount decreases. For this reason, compared with the case where only a power tard is performed, a stop crank value can be decentralized more and, thereby, the said effect can be heightened further.
On the other hand, in both the key-off operation and the idling stop, the power tard is executed only when the coolant temperature Tw is equal to or higher than the first determination value Tw1, and the power tard is prohibited when it is less than the first determination value Tw1. In the low temperature range, the viscosity of the hydraulic oil is high, so that the accurate operation of the forced exhaust valve opening mechanism 17 cannot be expected, and an inappropriate exhaust valve 15 forcibly opens the original stop crank position. In addition, for example, an adverse effect such as an increase in engine vibration at the time of stoppage occurs. However, in this embodiment, the power tard is prohibited, so that such an adverse effect can be prevented.
In addition, in the idle stop, the idle stop is executed only when the coolant temperature Tw is equal to or higher than the second determination value Tw2, and the idle stop is prohibited when the cooling water temperature Tw is lower than the second determination value Tw2. When the engine is cold, the amount of fuel needs to be increased and sufficient purification performance cannot be obtained.Therefore, warm-up should be completed as soon as possible, but in this embodiment, idle stop is prohibited. Correspondingly, the problems during the cold state can be minimized.

This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above-described embodiment, the present invention is embodied in a vehicle having an idle stop start function. However, the present invention is not limited to this. May be. In the case of an idle stop start vehicle, the engine stop by the idle stop is far more frequent than the engine stop by the key off operation. Therefore, the power stop is not executed for the key off operation, and the idle stop is executed. The power tard may be executed only in response to the engine stop command.
Further, in the above embodiment, the closing control of the intake throttle valve 14 is used together when the power tard is executed, but the intake throttle valve 14 does not necessarily need to be controlled. Therefore, for example, the intake throttle valve 14 may be eliminated and only the power tard may be executed when the engine is stopped.

In the above embodiment, the power tard is prohibited when the cooling water temperature Tw is lower than the first determination value Tw1, and the idle stop is prohibited when the cooling water temperature Tw is lower than the second determination value Tw2, but this is not restrictive. For example, the power tard may be executed even when the cooling water temperature Tw is lower than the first determination value Tw1, or the idle stop may be executed even when the cooling water temperature Tw is lower than the second determination value Tw2.
In the above embodiment, the delay time Tdly is set in advance based on the operation delay of the exhaust forced valve opening mechanism 17, and the fuel cut start timing is determined based on the elapse of the delay time Tdly. However, the present invention is not limited to this. The actual start of operation of the forced exhaust valve opening mechanism 17 may be detected. For example, a fuel pressure sensor may be provided on the slave piston 16 of any cylinder, and fuel cut may be started when it is determined that the operation of the forced exhaust valve opening mechanism 17 is started based on the detected rising of the oil pressure (operation start). Determination means).

1 Engine 14 Intake throttle valve 15 Exhaust valve 17 Exhaust forced valve opening mechanism 21 E / G-ECU
(Engine stop control means, operation start determination means, idle stop start control means)
22 ISS-ECU
(Stop instruction means, idle stop start control means)
25 Water temperature sensor (engine temperature detection means)

Claims (6)

Stop instruction means for instructing to stop the engine mounted on the vehicle;
Engine stop control means for stopping and stopping fuel injection to the engine based on the engine stop instruction by the stop instruction means;
An exhaust forced opening mechanism that temporarily forcibly opens the exhaust valve near the compression top dead center of the cylinder of the engine;
An operation start determination means for determining whether the operation delay of the exhaust forced valve opening mechanism has been eliminated and the forced opening of the exhaust valve has been started,
The engine stop control means starts the operation of the exhaust forced valve opening mechanism when the engine stop instruction is given by the stop instruction means, and the start determination of the exhaust valve forced opening by the operation start determination means. The engine stop control device is configured to stop the engine by stopping the fuel injection when the start determination is made.   The operation start determining means determines whether to start the forced opening of the exhaust valve when a preset delay time has elapsed from the start of the operation of the forced exhaust valve opening mechanism based on the operation delay of the exhaust forced valve opening mechanism. The engine stop control device according to claim 1, wherein: An intake throttle valve that restricts the intake air of the engine by closing the valve;
The engine stop control device according to claim 1 or 2, wherein the engine stop control means closes the intake throttle valve when the exhaust forced valve opening mechanism starts to operate. Engine temperature detecting means for detecting the temperature of the engine,
The engine stop control means prohibits the operation of the forced exhaust valve opening mechanism when the engine temperature detected by the engine temperature detection means is less than a preset first determination value. The engine stop control device according to any one of claims 1 to 3. The engine is mounted on the vehicle as a driving power source,
5. An idle stop start control means for stopping the engine when a preset engine stop condition is satisfied and starting the engine when a preset engine start condition is satisfied. The engine stop control device according to any one of the above. The engine is mounted on the vehicle as a driving power source,
Idle stop start control means for stopping the engine when a preset engine stop condition is satisfied, and starting the engine when a preset engine start condition is satisfied;
When the engine temperature detected by the engine temperature detecting means is less than a second determination value preset in a lower temperature side than the first determination value, the engine stop control means is configured to perform the engine based on the engine stop condition. The engine stop control device according to claim 4 , wherein the stop of the engine is prohibited.

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