WO2022153775A1

WO2022153775A1 - Engine

Info

Publication number: WO2022153775A1
Application number: PCT/JP2021/046438
Authority: WO
Inventors: 龍平河野; 翔平佐々木
Original assignee: ヤンマーホールディングス株式会社
Priority date: 2021-01-18
Filing date: 2021-12-16
Publication date: 2022-07-21
Also published as: CN116761935A; JP2022110305A

Abstract

This engine comprises: a fuel injection device for injecting fuel into a combustion chamber; an injection control unit that controls injection of the fuel by the fuel injection device on the basis of an injection parameter; and sensors that output values corresponding to the operation state of the engine. When a specific sensor included in the sensors is abnormal, the injection control unit uses a predetermined value set in advance instead of the output value from the specific sensor and corrects the injection parameter on the basis of the predetermined value.

Description

engine

The present invention relates to an engine.

Conventionally, an engine that controls the fuel injection amount based on the output value of a sensor (for example, a water temperature sensor) has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2-136546

For example, when a specific sensor (for example, a water temperature sensor) that has a great influence on fuel injection control is abnormal, the output value of the sensor becomes an erroneous value with respect to the output value when the sensor is normal. When an erroneous output value of a specific sensor is sent to the control unit, the control unit controls fuel injection based on the erroneous output value, which may cause a malfunction such as an engine malfunction. In this regard, Patent Document 1 does not study at all the control of fuel injection when a specific sensor is abnormal.

The present invention has been made to solve the above problems, and an object of the present invention is to appropriately control fuel injection even when a specific sensor is abnormal, and to cause problems such as engine malfunction. It is an object of the present invention to provide an engine capable of reducing the possibility of occurrence.

The engine according to one aspect of the present invention is an engine provided with a fuel injection device that injects fuel into a combustion chamber, and includes an injection control unit that controls injection of the fuel by the fuel injection device based on injection parameters. The injection control unit includes a sensor that outputs a value according to the operating state of the engine, and the injection control unit determines the output value of the specific sensor when the specific sensor included in the sensor is abnormal. Instead, a preset predetermined value is used, and the injection parameter is corrected based on the predetermined value.

According to the above configuration, even if a specific sensor is abnormal, it is possible to appropriately control the fuel injection and reduce the risk of malfunction such as engine malfunction.

It is a graph which shows the example of the torque curve in each operation mode of an engine. It is explanatory drawing which shows typically the schematic structure of the engine which concerns on embodiment of this invention. It is a block diagram which shows the structure of the main part of the said engine. It is explanatory drawing which shows typically the concept of fuel injection control in the said embodiment. It is a flowchart which shows the flow of processing by the said injection control.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

[1. Supplementary information on issues]
First, the description of the above-mentioned problems of the prior art will be supplemented. In recent years, regulations on engine exhaust gas have been tightened more and more in each country. Then, in order to comply with the above regulations, control is performed to perform each diagnosis of NCD (Nox Control Diagnosis) or PCD (Particulate Control Diagnosis). The NCD is a diagnosis related to the EGR device described later, and the PCD is a diagnosis related to the DPF (Diesel Particulate Filter) described later.

For example, if an abnormality occurs in a specific sensor and an error occurs in the diagnosis of NCD, the operation mode in which the engine power (torque, rotation speed) is gradually reduced is controlled. FIG. 1 shows an example of a torque curve in each operation mode. When an error is detected in the NCD, the operation mode is changed from the normal mode to the first mode (Low-level) after a predetermined time elapses from the error detection, and after the predetermined time elapses, the operation mode is changed from the first mode to the second mode. Control is performed to shift to the mode (Severe). When the maximum torque of the engine exceeds the value specified in each mode after the operation mode shifts to the first mode or the second mode, the above regulation cannot be properly satisfied.

Therefore, in the present embodiment, when a specific sensor is abnormal, the fuel injection control described later is performed to prevent the output of the engine from exceeding the specified value, that is, to reduce the malfunction of the engine. I am trying to do it.

[2. Engine configuration]
Hereinafter, the configuration of the engine of this embodiment will be described. FIG. 2 is an explanatory diagram schematically showing a schematic configuration of the engine 1 of the present embodiment. Further, FIG. 3 is a block diagram showing a configuration of a main part of the engine 1. The engine 1 is, for example, a diesel engine, and is mounted on a work vehicle (work machine), an agricultural machine, a ship, or the like.

The engine 1 includes an intake pipe 4 and an intake manifold 5 as intake system members. The intake pipe 4 sucks gas from the outside and supplies it to the intake manifold 5.

The intake manifold 5 divides the gas supplied from the intake pipe 4 into a number according to the number of cylinders (cylinders) (for example, four in FIG. 2) and supplies the gas to the cylinder head 6. The cylinder head 6 has a cylinder head cover (not shown) that covers each cylinder, and an injector 7 (fuel injection device) provided corresponding to the combustion chamber 6a of each cylinder. The injector 7 is controlled by an ECU (engine control unit) 9 and injects fuel stored at a high pressure in the common rail 8 into the combustion chamber 6a of each cylinder at a predetermined timing. That is, the engine 1 includes an injector 7 as a fuel injection device that injects fuel into the combustion chamber 6a. Each cylinder is provided with a piston that slides back and forth in the combustion chamber 6a and rotates the crank shaft via a connecting rod (connecting rod).

An intake air temperature sensor 11 is attached to the intake manifold 5. The intake air temperature sensor 11 detects the temperature of the gas in the intake manifold 5 and outputs it to the ECU 9.

The engine 1 includes an exhaust manifold 12, an exhaust pipe 13, and an exhaust gas purification device 14 as exhaust system members.

The exhaust manifold 12 collects the gases (exhaust gas) generated in the plurality of combustion chambers 6a. A part of the gas that has passed through the exhaust manifold 12 is supplied to the EGR device 18 via the EGR (Exhaust Gas Recirculation) pipe 17, and the remaining gas is supplied to the exhaust gas purification device 14 via the exhaust pipe 13.

The EGR device 18 is an exhaust gas recirculation device that returns a part of the exhaust gas discharged from the cylinder head 6 to the intake pipe 4, and includes an EGR cooler 19 and an EGR valve 20. The EGR cooler 19 cools the exhaust gas. The EGR device 18 changes the amount of exhaust gas supplied to the intake manifold 5 by adjusting the opening degree of the EGR valve 20. By mixing the exhaust gas with the gas taken into the intake manifold 5, the amount of oxygen in the gas taken in is reduced, so that the combustion temperature can be lowered. As a result, the generation of nitrogen oxides called NOx can be reduced, and exhaust gas regulations (emission regulations) can be met. The opening degree of the EGR valve 20 is detected by an EGR valve opening degree sensor (not shown).

When an abnormality occurs in the EGR device 18, the ECU 9 shifts the operation mode of the engine 1 to the first mode or the second mode described above, assuming that an error has occurred in the above-mentioned NCD diagnosis, and power (torque) of the engine 1 , The number of revolutions) is gradually changed (decreased) by fuel injection control.

The exhaust gas purification device 14 is a device that purifies and discharges exhaust gas, and is also called a DPF. The exhaust gas purification device 14 includes an oxidation catalyst 21 and a filter 22. The oxidation catalyst 21 is a catalyst for oxidizing (combusting) unburned fuel, carbon monoxide, nitrogen monoxide, etc. contained in the exhaust gas, and is composed of platinum or the like. The filter 22 is configured as, for example, a wall flow type filter, and collects PM (Particulate Matter) contained in the exhaust gas treated with the oxidation catalyst 21.

As shown in FIG. 3, the engine 1 further includes a water temperature sensor 31 and an engine speed sensor 32. The water temperature sensor 31 detects the temperature of the engine cooling water passing through the water jacket (not shown) provided in the cylinder head 6. The engine cooling water circulates and flows between the water jacket and the radiator through the cooling water channel by driving the water pump. The low-temperature engine cooling water cooled by the radiator passes through the water jacket to cool the engine body 1a including the cylinder head 6.

The engine rotation speed sensor 32 detects the rotation speed of the crank shaft of the engine 1 as the rotation speed of the engine 1. The information on the rotation speed detected by the engine rotation speed sensor 32 is output to the ECU 9.

Each of the above-mentioned sensors (intake air temperature sensor 11, water temperature sensor 31, engine speed sensor 32, etc.) detects each detection target and outputs a value according to the operating state of the engine 1 to the ECU 9. That is, the engine 1 of the present embodiment includes a sensor that outputs a value according to the operating state of the engine 1. In particular, the engine 1 of the present embodiment includes a plurality of sensors.

In addition, the engine 1 may further have other sensors such as an atmospheric pressure sensor that detects atmospheric pressure. By providing the atmospheric pressure sensor, the ECU 9 can recognize the altitude of the environment in which the engine 1 is used based on the detected atmospheric pressure, and can control the operating conditions of the engine 1 according to the recognized altitude.

The above-mentioned ECU 9 is a controller that controls the operation of each part of the engine 1. In particular, in the present embodiment, the ECU 9 functions as an injection control unit that controls fuel injection by the injector 7 based on the injection parameters. The above injection parameters include at least one of fuel injection amount, injection timing, and injection pressure. The ECU 9 also has a function as a timekeeping unit for measuring time. Further, the ECU 9 also has a storage unit for storing an injection map, which will be described later, a control program of the ECU 9, and the like.

By the way, when the engine 1 is in a low temperature state and the engine cooling water is at a low temperature, it is difficult to start the engine 1, so it is necessary to finely adjust the injection timing when the injector 7 injects fuel in multiple stages. Become. Therefore, it can be said that the temperature of the engine cooling water has a great influence on the fuel injection control.

Therefore, in the present embodiment, the water temperature sensor 31 that has a great influence on the fuel injection control is considered as a specific sensor, and the method of correcting the fuel injection timing and the like by the ECU 9 depends on whether or not an abnormality has occurred in the water temperature sensor 31. I try to change. Hereinafter, fuel injection control will be described more specifically.

[3. Fuel injection control flow]
FIG. 4 is an explanatory diagram schematically showing the concept of fuel injection control according to the present embodiment. Further, FIG. 5 is a flowchart showing a processing flow by fuel injection control according to the present embodiment. Here, as an example, consider fuel injection control when the work is performed by a work vehicle (for example, a hydraulic excavator) equipped with the engine 1 of the present embodiment.

First, the ECU 9 determines whether or not an abnormality has occurred in the water temperature sensor 31 (S1). For example, when a predetermined time elapses from the start of the engine 1, the engine 1 becomes warm and the temperature of the engine cooling water rises. Therefore, the ECU 9 can determine that the water temperature sensor 31 is normal if the output value (temperature) of the water temperature sensor 31 is equal to or higher than the threshold value after a predetermined time has elapsed from the start of the engine 1, and is less than the threshold value. If so, it can be determined that the water temperature sensor 31 is abnormal. If the water temperature sensor 31 is abnormal, the ECU 9 cannot diagnose the NCD and therefore recognizes the NCD error at the same time. If the water temperature sensor 31 is abnormal, the start of diagnosis of PCD is not permitted.

When the ECU 9 determines in S1 that the water temperature sensor 31 is normal (No in S1), the engine speed detected by the engine speed sensor 32, the indicated injection amount, and the injection map prepared in advance. The injection parameter is determined based on (S2).

Here, the indicated injection amount is an injection amount of fuel to be injected from the injector 7 (in multiple stages during one cycle), which is determined by the ECU 9 according to the opening degree of the accelerator stepped on by the operator who controls the work vehicle. When injecting, it means the total injection amount at each stage). The maximum value of the indicated injection amount is a value that can realize the maximum value (100%) of the torque that can be output by the engine 1. The opening degree of the accelerator is detected by an accelerator opening degree sensor (not shown) on the work vehicle side and input to the ECU 9.

Next, the ECU 9 corrects the injection parameter determined in S2 based on the output value (temperature of the engine cooling water) of the normal water temperature sensor 31 (S3). For example, when the output value of the water temperature sensor 31 is a relatively low temperature, the ECU 9 advances the fuel injection timing by an amount corresponding to the output value in order to facilitate ignition in the combustion chamber 6a. A correction value (for example, several degrees in advance) is calculated, and the correction value is added to the injection timing determined in S2. This correction is also called "environmental correction", and the above correction value is also called "environmental correction amount".

Subsequently, the ECU 9 injects fuel from the injector 7 in multiple stages with the injection parameters corrected in S3 (S4). As a result, as the relationship between the engine speed and the torque, for example, the torque curve in the normal mode shown in FIG. 1 can be obtained. After that, if the ignition key of the work vehicle is turned off in S5, the fuel injection is stopped and a series of processing is completed. If the ignition key is not OFF, the process returns to S1 and the processing after S1 is continued. Will be.

Even if the ECU 9 determines in S1 that the water temperature sensor 31 is abnormal (Yes in S1), if the first predetermined time (for example, 36 hours) has not elapsed since the occurrence of the abnormality (Yes in S6). , In order to avoid the inconvenience of work due to the shift to the first mode (power down of the engine 1), the above-described S2 and subsequent processes are executed without shifting the operation mode to the first mode.

On the other hand, the ECU 9 has not passed the first predetermined time (No in S6) and the second predetermined time (for example, 100 hours) after the occurrence of the abnormality of the water temperature sensor 31 (Yes in S7). , S8, and fuel injection control is performed in the first mode. Specifically, it is as follows.

In S8, the ECU 9 determines the injection parameters based on the engine speed and the indicated injection amount in the same manner as in S2. Here, the maximum torque (for example, 75% of the normal time) is defined by the injection map (maximum injection amount map) for the first mode. The maximum injection amount map is composed of the engine speed and the output value of the water temperature sensor 31.

Next, the ECU 9 uses a preset predetermined value (default value) instead of the output value of the water temperature sensor 31, and corrects the injection parameter determined in S8 based on the predetermined value (S9). The above-mentioned predetermined value is a representative value representing a value output from the water temperature sensor 31 when the water temperature sensor 31 is normal. For example, in S9, each injection timing in the multi-stage injection of fuel is corrected based on the predetermined value.

Subsequently, the ECU 9 injects fuel from the injector 7 in multiple stages with the injection parameters corrected in S9 (S4). As a result, as the relationship between the engine speed and the torque, for example, the torque curve in the first mode shown in FIG. 1 can be obtained. The torque in the torque curve indicates the maximum value of the torque that can be obtained in the first mode. After that, if the ignition key of the work vehicle is turned off in S5, the fuel injection is stopped and a series of processing is completed. If the ignition key is not OFF, the process returns to S1 and the processing after S1 is continued. Will be.

Further, in S7 described above, when the ECU 9 determines that the second predetermined time has elapsed from the occurrence of the abnormality of the water temperature sensor 31 (No in S7), the ECU 9 shifts to S10 and performs fuel injection control by the second mode. I do. Specifically, it is as follows.

In S10, the ECU 9 determines the injection parameters based on the engine speed and the indicated injection amount in the same manner as in S2. Here, the maximum torque (for example, 50% of the normal time) is defined by the injection map (maximum injection amount map) for the second mode. The maximum injection amount map is composed of the engine speed and the output value of the water temperature sensor 31.

After that, the process shifts to S9, and the ECU 9 uses a predetermined value set in advance instead of the output value of the water temperature sensor 31, and corrects the injection parameter (for example, injection timing) determined in S10 based on the predetermined value. .. Then, the ECU 9 injects fuel from the injector 7 in multiple stages with the injection parameters corrected in S9 (S4). As a result, as the relationship between the engine speed and the torque, for example, the torque curve in the second mode shown in FIG. 1 can be obtained. The torque in the torque curve indicates the maximum value of the torque that can be obtained in the second mode. After that, if the ignition key of the work vehicle is turned off in S5, the fuel injection is stopped and a series of processing is completed. If the ignition key is not OFF, the process returns to S1 and the processing after S1 is continued. Will be.

Since the water temperature sensor 31 was in an abnormal state by returning to S1 as needed after S5, for example, processing was performed in the order of S1, S6, S7, S10, S9, S4, S5, and then the water temperature sensor 31. When is returned to the normal state, processing can be performed in the order of S1, S2, S3, S4, S5. That is, when the water temperature sensor 31 returns from the abnormal state to the normal state, the correction of the injection parameter returns from the correction based on the predetermined value (S9) to the correction based on the output value of the normal water temperature sensor 31 (S3).

In the present embodiment, as shown in FIG. 4, if the water temperature sensor 31 is normal, the output value of the water temperature sensor 31 also for other control modules of the work vehicle that are not related to the control of the engine 1. Is supplied, and if the water temperature sensor 31 is abnormal, a predetermined value (default value) is supplied. In this case, it is possible to reduce the possibility of malfunction due to an abnormality of the water temperature sensor 31 in the control module on the work vehicle side.

Further, regardless of whether the water temperature sensor 31 is abnormal or normal, the output value of the water temperature sensor 31 is constantly monitored by the ECU 9. As a result, the ECU 9 can monitor whether or not the water temperature sensor 31 has recovered from the abnormal state based on the output value.

As described above, when the specific sensor (for example, the water temperature sensor 31) included in the sensor is abnormal, the ECU 9 as the injection control unit uses a preset predetermined value instead of the output value of the specific sensor. The injection parameter is corrected based on the predetermined value (S9).

If the ECU 9 corrects the injection parameter based on the output value of the specific sensor and controls the fuel injection based on the corrected injection parameter when the specific sensor is abnormal, the injection based on the incorrect output value is performed. There is a risk that problems such as malfunction of the engine 1 may occur due to parameter correction and erroneous injection control based on the injection parameters.

In the present embodiment, when a specific sensor is abnormal, the injection parameter is appropriately corrected based on the above-mentioned predetermined value instead of the erroneous output value. Therefore, fuel injection is performed based on the corrected injection parameter. Can be controlled appropriately. As a result, even if a specific sensor is abnormal, it is possible to reduce the possibility that a malfunction such as a malfunction of the engine 1 will occur. For example, even if the operation mode shifts to the first mode or the second mode due to an abnormality of a specific sensor, the engine can be controlled by appropriately correcting the above-mentioned injection parameters and controlling the fuel injection based on the corrected injection parameters. It is possible to suppress the maximum torque of 1 to a specified value or less (75% or less or 50% or less of the normal maximum torque).

By the way, in the present embodiment, even if a sensor other than the water temperature sensor 31 such as the intake air temperature sensor 11 is abnormal among the plurality of sensors, the ECU 9 corrects the injection parameter based on the presence or absence of the abnormality of the water temperature sensor 31. (S3, S9). That is, when a sensor other than the specific sensor is abnormal, the ECU 9 corrects the injection parameter based on the presence or absence of the abnormality of the specific sensor. In this case, it is possible to correct the injection parameters and control the fuel injection by emphasizing the presence or absence of abnormality in a specific sensor among the plurality of sensors.

In the present embodiment, when the specific sensor is normal, the ECU 9 corrects the injection parameter based on the output value of the specific sensor (S3). When a particular sensor is normal, the engine 1 is driven by a normal torque curve (torque limiting) by correcting normal injection parameters based on the output value of the particular sensor to control fuel injection. Can be operated (without).

In the present embodiment, the ECU 9 constantly monitors the output value of the specific sensor, and when the specific sensor returns from the abnormality to the normal state, the injection parameter is corrected and the output value of the specific sensor is corrected based on the predetermined value. Return to the correction based on the value (S9, S5, S1, S3).

By constantly monitoring the output value of the specific sensor, the ECU 9 can constantly monitor whether or not the specific sensor has returned from the abnormal state to the normal state based on the output value. Then, when the specific sensor returns to normal from the abnormality, the ECU 9 returns the correction of the injection parameter from the correction based on the predetermined value to the correction based on the output value of the specific sensor, thereby based on the output value. Normal fuel injection control can be restored.

Further, the ECU 9 determines that the specific sensor is abnormal when the output value of the specific sensor is less than the threshold value after a predetermined time has elapsed from the start of the engine 1 (S1). As a result, it is possible to accurately determine whether or not a specific sensor is abnormal.

Further, the specific sensor described above is a water temperature sensor 31 that detects the temperature of the cooling water of the engine. As described above, since the water temperature sensor 31 has a greater influence on the fuel injection control than the other sensors, when the specific sensor is the water temperature sensor 31, it is based on the output value or the predetermined value of the specific sensor. The control of the present embodiment that corrects the injection parameters and reduces the malfunction of the engine 1 is very effective.

Further, the above-mentioned predetermined value is a representative value of the output value when the specific sensor (water temperature sensor 31) is normal. As a result, even if there is an abnormality in the specific sensor, the injection parameter can be correctly corrected based on the above-mentioned predetermined value, and the fuel injection can be correctly controlled based on the corrected injection parameter. As a result, even if a specific sensor is abnormal, it is possible to surely reduce the possibility that a malfunction such as a malfunction of the engine 1 will occur.

Further, the above injection parameters include at least one of the fuel injection amount, injection timing, and injection pressure. By correcting at least one of these, the ECU 9 injects fuel from the injector 7 at an appropriate injection amount, injection timing or injection pressure based on the corrected injection parameters, such as malfunction of the engine 1. It is possible to avoid the possibility that a problem will occur.

Although the engine 1 of the present embodiment is not provided with a supercharger, the fuel injection control described in the present embodiment can be applied even if the engine 1 is provided with a supercharger.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to this, and can be extended or modified within a range that does not deviate from the gist of the invention.

The engine of the present invention can be used for, for example, work vehicles, agricultural machinery, and the like.

1 Engine 6a Combustion chamber 7 Injector (fuel injection device)
9 ECU (injection control unit)
11 Intake temperature sensor 31 Water temperature sensor (specific sensor)
32 Engine speed sensor

Claims

An engine equipped with a fuel injection device that injects fuel into the combustion chamber.
An injection control unit that controls the injection of the fuel by the fuel injection device based on the injection parameters.
A sensor that outputs a value according to the operating state of the engine is provided.
When the specific sensor included in the sensor is abnormal, the injection control unit uses a predetermined value set in advance instead of the output value of the specific sensor, and the injection control unit uses the predetermined value based on the predetermined value. An engine that corrects injection parameters.
The engine according to claim 1, wherein the injection control unit corrects the injection parameter based on the output value of the specific sensor when the specific sensor is normal.
The injection control unit constantly monitors the output value of the specific sensor, and when the specific sensor returns to normal from an abnormality, the injection parameter is corrected from the correction based on the predetermined value. The engine according to claim 1 or 2, which returns to the correction based on the output value of the sensor.
The injection control unit determines that the specific sensor is abnormal when the output value of the specific sensor is less than the threshold value after a predetermined time has elapsed from the start of the engine. The engine described in any of 3 to 3.
The engine according to any one of claims 1 to 4, wherein the specific sensor is a water temperature sensor that detects the temperature of the cooling water of the engine.
The engine according to any one of claims 1 to 5, wherein the predetermined value is a representative value representing a value output when the specific sensor is normal.