JP6837940B2 - Internal combustion engine drive control method and internal combustion engine drive control device - Google Patents

Description

The present invention relates to drive control of an internal combustion engine, and in particular, improves the stability and reliability of drive control of an internal combustion engine in an emergency in an internal combustion engine drive control device using a common rail fuel injection control device. Regarding.

As a fuel injection control device for an internal combustion engine such as a diesel engine, fuel is pressurized by a high-pressure pump and pumped to a common rail, which is a pressure accumulator, to accumulate pressure, and the accumulated high-pressure fuel is supplied to an injector to provide internal combustion by the injector. It is well known that a common rail type fuel injection control device capable of injecting high-pressure fuel into an engine is put into practical use as having excellent fuel efficiency and emission characteristics.

In such a common rail type fuel injection control device, as a configuration for controlling the rail pressure, for example, an electromagnetic metering valve for adjusting the fuel inflow amount is provided on the inflow side of the high pressure pump to indirectly control the rail pressure. At the same time, a pressure limiting valve that opens at a predetermined pressure is provided on the fuel return passage side of the common rail so that if the rail pressure inadvertently reaches the predetermined pressure, the fuel in the common rail can be discharged to the return side. , A configuration that ensures the safety of the device and the like have been proposed and put into practical use (see, for example, Patent Document 1 and the like).

In the common rail fuel injection control device having such a configuration, the pressure sensor is one of the important elements as an element for detecting the rail pressure essential for rail pressure control, fuel injection control, and the like.
Therefore, in the common rail fuel injection control device having the above configuration, when the pressure sensor is determined to be a failure by the failure diagnosis process, the electromagnetic adjustment is usually performed from the viewpoint of ensuring safe driving. The meter valve is forcibly fully opened, thereby increasing the rail pressure and intentionally opening the pressure limiting valve, and fuel injection control is performed as described below to maintain the minimum running. Such measures are taken.

That is, when the pressure limiting valve is opened, the rail pressure usually converges to a predetermined pressure that appears after the pressure control valve is opened, that is, a pressure called a secondary pressure. Therefore, assuming that this secondary pressure is the actual rail pressure, the fuel injection amount corresponding to the rail pressure is calculated, and the fuel injection control is executed, so that the minimum necessary amount generally called the limp home mode is obtained. The safety of the vehicle is ensured by making it possible to ensure the running condition.

Japanese Unexamined Patent Publication No. 2014-88410

However, the above-mentioned limp home mode presupposes that the pressure limiting valve opens normally, but even if the parts are manufactured so as to minimize the failure rate, the occurrence of failure is denied as a possibility. The same is true for pressure limiting valves.
That is, it cannot be denied that the pressure limiting valve may not reach the original valve opening state for some reason, and in this case, the rail pressure may not drop to the secondary pressure.

However, even if the pressure limiting valve is not fully opened, the high-pressure pump is in the full pressure feed state, so the same fuel as when the pressure limiting valve is normally opened is supplied to the rail. , More fuel injection than necessary will be done. As a result, the engine becomes in a high load state, and in the worst case, the engine may fail.

The present invention has been made in view of the above circumstances, and is an internal combustion engine drive control method and an internal combustion engine drive that can ensure minimum running regardless of the presence or absence of a failure of the pressure limiting valve in the event of a pressure sensor failure. It provides a control device.

In order to achieve the above object of the present invention, the internal combustion engine drive control method according to the present invention is
The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, enabling injection of high-pressure fuel into the internal combustion engine via a fuel injection valve connected to the common rail, and an electromagnetic type on the upstream side of the high-pressure pump. An internal combustion engine in which a metering valve is provided on the downstream side of the high-pressure pump, and a pressure limiting valve is provided on the downstream side of the high-pressure pump, and the rail pressure of the common rail can be controlled by driving control of the electromagnetic metering valve by an electronic control unit. This is an internal combustion engine drive control method for an engine drive control device.
When a failure of the pressure sensor is detected, isochronous control is started, and when the internal combustion engine reaches a desired operating state, the correlation between the preset energization time of the fuel injection valve and the rail pressure is established. Based on this, the rail pressure with respect to the energization time of the fuel injection valve at this time is obtained as the estimated rail pressure, and when the estimated rail pressure is lower than the predetermined reference pressure, the operation in the limp home mode is permitted. It will be.
Further, in order to achieve the above object of the present invention, the internal combustion engine drive control device according to the present invention may be used.
The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, enabling injection of high-pressure fuel into the internal combustion engine via a fuel injection valve connected to the common rail, and an electromagnetic type on the upstream side of the high-pressure pump. An internal combustion engine in which a metering valve is provided on the downstream side of the high-pressure pump, and a pressure limiting valve is provided on the downstream side of the high-pressure pump, and the rail pressure of the common rail can be controlled by driving control of the electromagnetic metering valve by an electronic control unit. It is an engine drive control device
The electronic control unit is
When a failure of the pressure sensor is detected, isochronous control is started, and when it is determined that the internal combustion engine is in a desired operating state, the preset energization time of the fuel injection valve and the rail pressure are set. Based on the correlation, the rail pressure with respect to the energization time of the fuel injection valve at this time is obtained as the estimated rail pressure, and when the estimated rail pressure is lower than the predetermined reference pressure, the operation in the limp home mode is allowed. It is composed.

According to the present invention, in the case of a pressure sensor failure, when a predetermined condition is satisfied by using the rail pressure obtained from the correlation between the energization time of the fuel injection valve used in isochronous control and the rail pressure as an estimated value. By using it in the limp home home mode, even if the pressure limiting valve fails, the operation of the vehicle in the limp home mode is secured and maintained, so the internal combustion engine is more reliable and safer than before. This has the effect of ensuring the operating condition of the engine.

It is a block diagram which shows the structural example of the common rail type fuel injection control apparatus to which the internal combustion engine drive control method in embodiment of this invention is applied. It is a subroutine flowchart which shows the procedure of the first half part of the procedure of the internal combustion engine drive control processing in embodiment of this invention executed in the common rail type fuel injection control apparatus shown in FIG. It is a subroutine flowchart which shows the procedure of the latter half part of the procedure of the internal combustion engine drive control processing in embodiment of this invention executed in the common rail type fuel injection control apparatus shown in FIG. It is a characteristic diagram which shows an example of the correlation between the energization time of a fuel injection valve, and a rail pressure.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
The members, arrangements, etc. described below are not limited to the present invention, and can be variously modified within the scope of the gist of the present invention.
First, a configuration example of a fuel injection control device used in an internal combustion engine to which the internal combustion engine drive control method according to the embodiment of the present invention is applied will be described with reference to FIG.

The fuel injection control device for an internal combustion engine shown in FIG. 1 is specifically an example of a common rail fuel injection control device, and the common rail fuel injection control device is a high pressure pump device 50 that pumps high pressure fuel. A common rail 1 that stores the high-pressure fuel pumped by the high-pressure pump device 50, and a plurality of fuel injection valves 2-1 that inject and supply the high-pressure fuel supplied from the common rail 1 to the cylinders of the engine 3 as an internal combustion engine. ~ 2-n and an electronic control unit (denoted as "ECU" in FIG. 1) 4 that executes fuel injection control processing, internal combustion engine drive control processing, etc., which will be described later, are configured as main components. .. This configuration itself is the same as the basic configuration of a conventionally well-known fuel injection control device of this type.

The high-pressure pump device 50 has a known and well-known configuration in which the supply pump 5, the metering valve 6, and the high-pressure pump 7 are the main components.
In such a configuration, the fuel in the fuel tank 9 is pumped up by the supply pump 5 and supplied to the high pressure pump 7 via the metering valve 6. An electromagnetic proportional control valve is used for the metering valve 6, and the amount of energization thereof is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high-pressure pump 7, in other words, the discharge of the high-pressure pump 7. The amount is to be adjusted.
Fuel pressurized by the high-pressure pump 7 is pumped to the common rail 1.

A return valve 8 is provided between the output side of the supply pump 5 and the fuel tank 9, so that the surplus fuel on the output side of the supply pump 5 can be returned to the fuel tank 9. ..
Further, the supply pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50, or may be provided in the fuel tank 9.

The fuel injection valves 2-1 to 2-n are provided for each cylinder of the engine 3, and each receives high-pressure fuel from the common rail 1 and injects fuel by injection control by the electronic control unit 4. There is.

The common rail 1 according to the embodiment of the present invention is provided with a so-called mechanical pressure limiting valve 10 in a return passage (not shown) for returning excess fuel to the tank 9, and the rail pressure in the common rail 1 is increased. When the predetermined pressure (valve opening pressure) set in the pressure limiting valve 10 is exceeded, the pressure limiting valve 10 is opened, and the fuel of the common rail 1 is sent to the tank 9 via the return passage (not shown) on the low pressure side. By discharging, the inadvertent increase in rail pressure is restricted.

The electronic control unit 4 has, for example, a microcomputer (not shown) having a known and well-known configuration, a storage element (not shown) such as RAM and ROM, and a fuel injection valve 2-. A circuit for energizing and driving 1 to 2-n (not shown) and a circuit for energizing and driving the metering valve 6 and the like (not shown) are configured as main components.

In addition to inputting detection signals from the pressure sensor 11 that detects the pressure of the common rail 1, various detection signals such as engine speed, accelerator opening, and fuel temperature are used to inject fuel from the engine 3 into the electronic control unit 4. It is input to be used for control processing, internal combustion engine drive control processing in the embodiment of the present invention described later, and the like.

2 and 3 show a flowchart of the procedure of the internal combustion engine drive control process according to the embodiment of the present invention, and the contents thereof will be described below with reference to the same figure.
When the processing by the electronic control unit 4 is started, the failure diagnosis processing is executed (see step S102 in FIG. 2).
The failure diagnosis process has been conventionally performed in this type of device, and performs a predetermined diagnosis such as the presence or absence of a failure of various sensors having a great influence on the running control of the vehicle and the presence or absence of an abnormality in various control data. It is something to do.

The internal combustion engine drive control process according to the embodiment of the present invention is in a standby state until it is determined that some failure has occurred in the failure diagnosis process (see step S104 in FIG. 2), and when it is determined that a failure has occurred, it is determined. Whether or not the pressure sensor has failed is determined (see step S106 in FIG. 2). If it is determined that a pressure sensor failure has occurred (YES), the process proceeds to step S108 described below, while if it is determined that a pressure sensor failure has not occurred (NO), the process proceeds to step S108 described below. The process proceeds to step S130, which will be described later.

In step S108, isochronous control is started.
The isochronous control itself is not unique to the present invention, and has been put into practical use as one of the engine rotation controls executed in, for example, agricultural vehicles and construction vehicles. Hereinafter, isochronous control will be described in detail.

In isochronous control, normally, when the accelerator opening is kept constant, the engine speed is almost maintained at the speed corresponding to the accelerator opening, and the fuel injection amount is adjusted according to the required torque. There is. That is, in isochronous control, the engine output is adjusted in response to load fluctuations while keeping the engine speed constant.

It is assumed that normal engine rotation control is being executed until isochronous control is started.
That is, data necessary for engine rotation control such as the target fuel injection amount and the target rail pressure are calculated based on the actual engine rotation speed, accelerator opening, actual rail pressure, etc., and each target is calculated based on the obtained data. Fuel injection is performed by appropriately using feedback control, feed forward control, and the like so that the value is achieved, and a desired engine rotation state is achieved.

Next, the high-pressure pump 7 is brought into the full pressure feeding state (see step S110 in FIG. 2). That is, the metering valve 6 is fully opened, and the high-pressure pump 7 is in a state of pumping fuel to the common rail 1 at the maximum discharge amount (fully pumped state).

Next, the vehicle speed is measured (see step S112 in FIG. 2), and it is determined whether or not the vehicle speed V is zero, that is, whether or not the vehicle is stopped (see step S114 in FIG. 2).
In step S114, if it is determined that the vehicle speed is zero (YES), the process proceeds to step S116 described below, while if it is determined that the vehicle speed is not zero (NO), the process proceeds to step S116 described below. The process returns to step S112.

That is, the processes after step S116 are not executed until the vehicle speed is determined to be zero. This is because the processing after step S116 is executed in a relatively stable state such as an idling state, so that a reliable processing result can be obtained.

In step S116, the engine speed Ne is measured.
Next, it is determined whether or not the engine speed Ne is within a predetermined speed range (Ne1 <Ne <Ne2) (see step S118 in FIG. 2).
Here, the predetermined range of the engine speed is the range of the engine speed to which the isochronous control is applied.

As will be described later, the range of the engine speed is such that the estimated value of the rail pressure is obtained based on the correlation between the energization time of the fuel injection valves 2-1 to 2-n in isochronous control and the rail pressure. This is to make the process executable.

If it is determined in step S118 that the engine speed Ne is within the predetermined speed range (YES), the process proceeds to step S120 (see FIG. 3), while the engine speed Ne is predetermined. If it is determined that the rotation speed is not within the range (NO), the process returns to the previous step S112, and the series of processes after step S112 are repeated.

In step S120, the energization time ET of the fuel injection valves 2-1 to 2-n at this time is measured.
Since the energization time ET is normally acquired in the engine control process during the normal operation as in the conventional case, it is not necessary to independently measure the energization time in step S120. And, it is sufficient to divert the one acquired by the engine control processing executed separately from the processing shown in FIG.

Next, the estimated rail pressure Pr is acquired (see step S122 in FIG. 3).
For the acquisition of the estimated rail pressure Pr, an energization time / rail pressure map stored in advance in an appropriate storage area of the electronic control unit 4 is used for isochronous control.

This energization time / rail pressure map shows the correlation between the energization time ET of the fuel injection valves 2-1 to 2-n when isochronous control is executed and the rail pressure maintained at that time. , FIG. 4 shows an example of graphing it.
The energization time / rail pressure map is configured such that a plurality of main energization time ETs and rail pressures corresponding to the energization time ETs can be read out with the energization time ET as an input parameter. Since the rail pressure corresponding to the energization time stored in the energization time / rail pressure map is discrete, it is preferable to calculate the rail pressure with respect to the stored energization time by an interpolation method.

Next, when it is determined whether or not the estimated rail pressure Pr acquired as described above exceeds the predetermined reference pressure Ptarget (see step S124 of FIG. 3), and it is determined that the estimated rail pressure Pr exceeds the predetermined reference pressure Ptarget. If (YES), the engine is stopped assuming that the vehicle is not in a running state, and a series of processes is completed (see step S126 in FIG. 3).

Here, it is preferable that the predetermined reference pressure Ptarget is set for each individual vehicle based on the test result, the simulation result, etc. while considering the specific specifications of the vehicle and the like.
Earlier, in the energization time / rail pressure map shown in FIG. 4, as an example, an area for engine stop and an area for engine operation maintenance (keep driving) are indicated by arrows. There is.

On the other hand, when it is determined in step S124 that the estimated rail pressure Pr does not exceed the predetermined reference pressure Ptarget (NO), the engine control returns to the operating state based on the normal control (see step S128 of FIG. 3). ), So-called limp home mode operation (allowing limp home mode operation) (see step S130 in FIG. 3).

In step S106, when it is determined that the pressure sensor 11 has not failed and the limp home mode operation is executed, the energization time of the fuel injection valves 2-1 to 2-n is determined by the pressure sensor 11. It is determined based on the detected actual rail pressure.

When the pressure sensor fails, it can be applied to an internal combustion engine drive control device in which it is desired to secure a minimum running state regardless of whether or not the pressure limiting valve has failed.

1 ... Common rail 2-1 to 2-n ... Fuel injection valve 3 ... Engine 4 ... Electronic control unit 6 ... Metering valve 10 ... Pressure limiting valve 11 ... Pressure sensor 50 ... High pressure pump device

Claims (6)

The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, enabling injection of high-pressure fuel into the internal combustion engine via a fuel injection valve connected to the common rail, and an electromagnetic type on the upstream side of the high-pressure pump. An internal combustion engine in which a metering valve is provided on the downstream side of the high-pressure pump, and a pressure limiting valve is provided on the downstream side of the high-pressure pump, and the rail pressure of the common rail can be controlled by driving control of the electromagnetic metering valve by an electronic control unit. This is an internal combustion engine drive control method for an engine drive control device.
When a failure of the pressure sensor is detected, isochronous control is started, and when the internal combustion engine reaches a desired operating state, the correlation between the preset energization time of the fuel injection valve and the rail pressure is established. Based on this, the rail pressure with respect to the energization time of the fuel injection valve at this time is obtained as the estimated rail pressure, and when the estimated rail pressure is lower than the predetermined reference pressure, the operation in the limp home mode is permitted. Internal combustion engine drive control method. A claim characterized in that the internal combustion engine is in the desired operating state when the discharge amount of the high-pressure pump is maximized, the vehicle speed is zero, and the rotation speed of the internal combustion engine is within a predetermined range. Item 1. The internal combustion engine drive control method according to item 1. The internal combustion engine drive control method according to claim 1, wherein the operation of the internal combustion engine is stopped when the estimated rail pressure exceeds a predetermined reference pressure. The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, enabling injection of high-pressure fuel into the internal combustion engine via a fuel injection valve connected to the common rail, and an electromagnetic type on the upstream side of the high-pressure pump. An internal combustion engine in which a metering valve is provided on the downstream side of the high-pressure pump, and a pressure limiting valve is provided on the downstream side of the high-pressure pump, and the rail pressure of the common rail can be controlled by driving control of the electromagnetic metering valve by an electronic control unit. It is an engine drive control device
The electronic control unit is
When a failure of the pressure sensor is detected, isochronous control is started, and when it is determined that the internal combustion engine is in a desired operating state, the preset energization time of the fuel injection valve and the rail pressure are set. Based on the correlation, the rail pressure with respect to the energization time of the fuel injection valve at this time is obtained as the estimated rail pressure, and when the estimated rail pressure is lower than the predetermined reference pressure, the operation in the limp home mode is allowed. An internal combustion engine drive control device characterized by being configured. The electronic control unit determines that the internal combustion engine is in the desired operating state when the discharge amount of the high-pressure pump is maximized, the vehicle speed is zero, and the rotation speed of the internal combustion engine is within a predetermined range. The internal combustion engine drive control device according to claim 4, wherein the internal combustion engine drive control device is configured to be the same. The internal combustion engine drive control device according to claim 5, wherein the electronic control unit is configured to stop the operation of the internal combustion engine when the estimated rail pressure exceeds a predetermined reference pressure.

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