JP2022088860A - Controller for internal combustion engine - Google Patents

Abstract

To lighten an operation load of execution of time synchronization processing and rotation synchronization processing on a controller for an internal combustion engine.SOLUTION: An electronic controller 240 for an internal combustion engine comprises a global RAM 240C that a CPU 240A, an input/output circuit 240D and a communication circuit 240E can access, and a local RAM 240H that only the CPU 240A can access, and executes time synchronization processing synchronized with time and rotation synchronization processing synchronized with rotation of an internal combustion engine. Here, the local RAM 240H has characteristics of a high access speed, but a small storage region as compared with the global RAM 240C. At least part of data used in the rotation synchronization processing is statically allocated to the local RAM 240H.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device for an internal combustion engine.

When controlling an internal combustion engine mounted on a vehicle such as an automobile, it is described in Japanese Patent Application Laid-Open No. 2013-142306 (Patent Document 1) in addition to a time synchronization process (steady process) executed at predetermined time intervals such as failure diagnosis. Therefore, it is necessary to execute rotation synchronization processing such as fuel injection control and ignition control in synchronization with the pulse signal proportional to the engine speed.

Japanese Unexamined Patent Publication No. 2013-142306

By the way, in the control of an internal combustion engine, for example, in order to ensure responsiveness, drivability, etc., the time synchronization process and the rotation synchronization process must be completed within a predetermined control cycle (control cycle). However, since the number of rotation synchronization processes executed increases in proportion to the engine speed, the computational load for executing the rotation synchronization process increases in the region where the engine speed is high. If the control cycle is set so that the time synchronization processing and the rotation synchronization processing that can be expected within the control cycle are completed in the region where the engine speed is high, the time synchronization processing is executed in the region where the engine speed is low. There is a possibility that the required function cannot be achieved due to the long time interval.

Therefore, an object of the present invention is to provide a control device for an internal combustion engine capable of reducing the calculation load for executing the time synchronization process and the rotation synchronization process.

The control device of the internal combustion engine includes a first volatile memory and a second volatile memory having a faster access speed, and performs time-synchronized time-synchronized processing and rotation-synchronized processing synchronized with the rotation of the internal combustion engine. Execute each. Then, at least a part of the data used in the rotation synchronization process is statically allocated to the second volatile memory.

According to the present invention, it is possible to reduce the calculation load for executing the time synchronization process and the rotation synchronization process in the control device of the internal combustion engine.

It is a schematic diagram which shows an example of the engine system for a vehicle. It is a perspective view which shows the detail of the variable valve timing mechanism. It is a schematic diagram which shows an example of an electronic control device. It is explanatory drawing of the relationship between the engine speed and the calculation load. It is a figure which shows the relationship between the engine speed and the calculation load. It is explanatory drawing of the arithmetic load at the time of allocating data to the non-volatile memory with a slow access speed. It is explanatory drawing of the arithmetic load at the time of allocating data to the non-volatile memory with high access speed. It is a figure which shows the relationship between the engine speed and the calculation load when data is assigned to the non-volatile memory which has a high access speed. It is explanatory drawing of the arithmetic load in the case where the data with a short bit length is preferentially allocated to the non-volatile memory having a slow access speed, and the data with a long bit length is preferentially allocated to the non-volatile memory with a high access speed. It is explanatory drawing of the arithmetic load in the case where the data with a short bit length is preferentially allocated to the non-volatile memory having a high access speed, and the data with a long bit length is preferentially allocated to the non-volatile memory having a slow access speed. It is explanatory drawing of the effect of allocating data preferentially to a non-volatile memory having a high access speed.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a system configuration of an engine for a vehicle such as a passenger car, a truck, a bus, and a construction machine to which a control device for an internal combustion engine according to the present embodiment can be applied.

The engine 100 (internal combustion engine) is, for example, an in-line 4-cylinder gasoline engine, and the intake port 120 for introducing intake air (intake air) into the combustion chamber 110 of each cylinder opens and closes a tip opening facing the combustion chamber 110. An intake valve 130 is provided. Further, at a predetermined position on the upper part of the engine 100, an in-cylinder injection type fuel injection valve 140 that directly injects fuel into the combustion chamber 110, and an ignition that ignites and burns a mixture of fuel and intake air existing in the combustion chamber 110. Plugs 150 are attached to each.

When a magnetic attraction force is generated by energizing the electromagnetic coil, the fuel injection valve 140 lifts the valve body urged in the valve closing direction by a spring to open the valve, and the fuel is burned from the nozzle injection hole at the tip to the combustion chamber. It is injected and supplied into 110. The fuel injection valve 140 is supplied with fuel regulated to a predetermined pressure so that the fuel is injected in proportion to the valve opening time of the valve body. The fuel injection valve 140 is not limited to the in-cylinder injection type fuel injection valve, and may be a port injection type fuel injection valve that injects fuel into the intake port 120.

The fuel injected from the fuel injection valve 140 into the combustion chamber 110 forms a dense layer around the spark plug 150 attached to the upper part of the engine 100, and is ignited and burned by the spark ignition of the spark plug 150. Then, this combustion pressure pushes down the piston 160 toward the crankshaft (not shown), thereby driving the crankshaft to rotate.

Further, an exhaust valve 180 that opens and closes a tip opening facing the combustion chamber 110 is arranged in the exhaust port 170 that leads out the exhaust from the combustion chamber 110. Then, when the exhaust valve 180 is opened, the exhaust gas is discharged from the combustion chamber 110 through the gap between the exhaust port 170 and the exhaust valve 180. Hazardous substances (carbon monoxide CO, hydrocarbon HC and nitrogen oxide NOx) contained in the exhaust discharged from the combustion chamber 110 are purified into harmless components by a three-way catalyst (not shown) and then released into the atmosphere. ..

At the end of the intake camshaft 190 that opens and closes the intake valve 130, the rotation phase of the intake camshaft 190 with respect to the crankshaft is changed according to the engine operating state for the purpose of improving output, improving fuel efficiency, suppressing exhaust, and the like. A variable valve timing mechanism (VTC) 200 that changes the valve timing of the intake valve 130 is attached.

As shown in FIG. 2, the VTC 200 is integrated with a cam sprocket 202 around which a cam chain that transmits a rotational driving force of a crankshaft is wound, and a cam sprocket is provided by an actuator 204 such as an electric motor having a built-in speed reducer. By rotating the intake camshaft 190 relative to 202, the valve timing is advanced or retarded. Here, the member indicated by reference numeral 206 in FIG. 2 is a connector for connecting a harness that supplies a drive signal to the actuator 204.

The VTC 200 is not limited to the configuration shown in FIG. 2, and may have any configuration as long as the valve timing can be changed by various actuators such as an electric motor and a hydraulic motor. Further, the VTC 200 is not limited to the intake camshaft 190, and may be provided on both the exhaust camshaft 210 that opens and closes the exhaust valve 180, or both the intake camshaft 190 and the exhaust camshaft 210.

As a control system for the engine 100, a crank angle sensor 220 that outputs a crank angle signal including a pulse signal indicating a rotation angle from a reference position (for example, a top dead point position) of a crankshaft at a predetermined position of the engine 100. Further, a cam angle sensor 230 that outputs a cam angle signal including a pulse signal for discriminating each cylinder is attached. Here, the crank angle sensor 220 detects a protrusion of the plate PT that rotates integrally with the crankshaft (the tooth is missing at the top dead center position), and outputs a pulse signal at each predetermined rotation angle.

The crank angle signal of the crank angle sensor 220 and the cam angle signal of the cam angle sensor 230 are input to the electronic control device 240 that controls the engine 100, respectively. The crank angle sensor 220 and the cam angle sensor 230 are mentioned as an example of the rotation sensor, and the electronic control device 240 is mentioned as an example of the control device of the internal combustion engine.

As shown in FIG. 3, the electronic control device 240 includes a CPU (Central Processing Unit) 240A, a ROM (Read Only Memory) 240B, a global RAM (Random Access Memory) 240C, an input / output circuit 240D, and a communication circuit 240E. And an internal bus 240F that connects them so that they can communicate with each other. Further, the electronic control device 240 further includes a local RAM 240H which is directly connected to the CPU 240A by the channel 240G. The global RAM 240C is mentioned as an example of the first volatile memory, and the local RAM 240H is mentioned as an example of the second volatile memory.

The CPU 240A is hardware that executes an instruction set (data transfer, calculation, processing, control, management, etc.) described in an application program, and is composed of an arithmetic unit, registers for storing instructions and data, peripheral circuits, and the like. Has been done. The ROM 240B includes, for example, a non-volatile memory such as a flash ROM or an EEPROM (Electrically Erasable Programmable Read Only Memory) that can retain data even when the power supply is cut off, and is an application program (computer program) that implements this embodiment. Holds learning values, failure information, etc. The global RAM 240C comprises, for example, a volatile memory such as a dynamic RAM in which data is lost when the power supply is cut off, and provides a storage area accessible to the CPU 240A, the input / output circuit 240D, and the communication circuit 240E.

The input / output circuit 240D includes, for example, an A / D converter, a D / A converter, a D / D converter, and the like, and provides input / output functions for analog and digital signals to various sensors, switches, actuators, and the like. The communication circuit 240E comprises, for example, a CAN (Controller Area Network) transceiver and provides a function of connecting to an in-vehicle network (not shown) such as a CAN. The internal bus 240F is a route for exchanging data between each device, and is an address bus for transferring addresses, a data bus for transferring data, timing and control information for actual input / output on the address bus or data bus. Includes a control bus to exchange.

The channel 240G is a data transmission line different from the internal bus 240F, and enables high-speed transmission / reception of arbitrary data between two devices. The local RAM 240H comprises, for example, a volatile memory such as a dynamic RAM in which data is lost when the power supply is cut off, and provides a storage area accessible only by the CPU 240A. Here, the local RAM 240H has a characteristic that the access speed is higher than that of the global RAM 240C, but the capacity is smaller than that of the global RAM 240C.

In addition to the crank angle signal of the crank angle sensor 220 and the cam angle signal of the cam angle sensor 230, the CPU 240A of the electronic control device 240 receives the intake flow rate and the cooling water temperature from various sensors (not shown) via the input / output circuit 240D. And the battery voltage etc. are input respectively. Further, the CPU 240A of the electronic control device 240 calculates the engine rotation speed from the crank angle signal and generates an engine rotation signal in which a pulse signal appears for each unit angle from the crank angle signal and the cam angle signal.

Then, the CPU 240A of the electronic control device 240 controls the fuel injection valve 140, the spark plug 150, and the VTC 200, respectively, according to the application program stored in the ROM 240B, as described below. Here, in the fuel injection control by the fuel injection valve 140, for example, so-called "sequential injection control" in which individual fuel injections are performed according to the compression stroke of each cylinder is performed. The VTC 200 may be controlled by a separate electronic control device different from the electronic control device 240.

The CPU 240A of the electronic control device 240 calculates the basic fuel injection amount, the fuel injection timing, and the ignition timing according to the engine operating state, respectively, based on the intake air flow rate and the engine rotation speed. Further, the CPU 240A of the electronic control device 240 calculates the fuel injection amount corrected for the basic fuel injection amount based on the cooling water temperature and the battery voltage. Then, the CPU 240A of the electronic control device 240 determines whether or not the fuel injection timing or the ignition timing has been reached in synchronization with the engine rotation signal (pulse signal for each unit angle), and the fuel injection valve is determined according to the determination result. The injection signal is output to 140, or the ignition signal is output to the spark plug 150. In this way, the processor 240A of the electronic control device 240 executes rotation synchronization processing such as fuel injection control and ignition control synchronized with the rotation of the engine 100.

Further, the CPU 240A of the electronic control device 240 calculates the target angle of the VTC 200 according to the engine operating state based on the intake air flow rate and the engine rotation speed every predetermined time (control cycle). Then, the CPU 240A of the electronic control device 240 feedback-controls the actuator 204 of the VTC 200 so that the actual angle of the intake camshaft 190 with respect to the crankshaft approaches the target angle. The control of the VTC 200 is given as an example of the time synchronization process executed in synchronization with the time.

Here, the relationship between the engine speed and the calculation load will be described.
In the electronic control device 240, for example, in order to ensure responsiveness, drivability, and the like, as shown in FIG. 4, the time synchronization process and the rotation synchronization process must be completed within a predetermined control cycle. The time synchronization process is executed, for example, at the beginning of the control cycle. When the pulse of the engine rotation signal is output due to the rotation of the engine 100, the time synchronization processing during execution is interrupted and saved, and the rotation synchronization processing is executed by the interrupt. Then, when the execution of the rotation synchronization process is completed, the saved time synchronization process is restored and restarted.

As the engine speed increases, the pulse of the engine rotation signal output within the control cycle increases in proportion to this. Therefore, the number of executions of the time synchronization process executed when the pulse of the engine rotation signal is output increases, and the number of times of reading / writing the data used in the time synchronization process to the RAM increases. As a result, the number of times of access to the RAM, which takes a long time as compared with the arithmetic operation and the logical operation in the processor 240A, increases, the execution time of the time synchronization processing and the rotation synchronization processing in the control cycle becomes long, and the calculation load increases. Will end up. For this reason, as shown in FIG. 5, the calculation load increases substantially linearly as the engine speed increases.

Explaining with the example shown in FIG. 4, assuming that the calculation load of the time synchronization processing in the control cycle is 40% and the calculation load of one rotation synchronization processing in the control cycle is 10%, the rotation synchronization processing once in the control cycle. Is executed, the computational load in the control cycle is 40 + 10 = 50%. When the engine speed increases and the rotation synchronization process is executed twice within the control cycle, the calculation load in the control cycle becomes 40 + 10 × 2 = 60%. When the engine speed is further increased and the synchronization processing is executed four times within the control cycle, the calculation load in the control cycle becomes 40 + 10 × 4 = 80%. Therefore, from this example as well, it can be understood that the computational load increases substantially linearly as the engine speed increases.

Therefore, by statically allocating the data used in the rotation synchronization processing executed in synchronization with the engine rotation to the local RAM 240H, which has a high access speed per data, the access time to the RAM is shortened and the control cycle is controlled. To reduce the calculation load in. The data statically allocated to the local RAM 240H can be set in the application program. That is, the data used in the rotation synchronization process is not dynamically allocated during the execution of the application program, but the designer or developer directly assigns the address of the local RAM 240H when writing the code of the application program. Specify and statically assign.

When the data used in the rotation synchronization process is assigned to the global RAM 240C having a low access speed, the access time to the global RAM 240C takes only the time indicated by the size of the arrow in FIG. However, when the data used in the rotation synchronization process is assigned to the local RAM 240H having a high access speed, as shown by the size of the arrow in FIG. 7, the access time to the local RAM 240H is compared with the case where the data is assigned to the global RAM 240C. Becomes shorter. Therefore, the execution time of the time synchronization process and the rotation synchronization process in the control cycle is shortened, and as shown in FIG. 8, the calculation load in the high rotation speed region of the engine rotation speed can be reduced.

When the data used in the rotation synchronization process is assigned to the local RAM 240H, most of the data used in the time synchronization process is assigned to the global RAM 240C having a low access speed. Therefore, in the low engine speed region, the time required to execute the time synchronization process increases, and as shown in FIG. 8, the control load increases. However, since the number of times the time synchronization process is executed is relatively small in the low engine speed region, the time synchronization process and the rotation synchronization process are performed within the control cycle even if the calculation load for executing the time synchronization process increases to some extent. It can be completed and no problems occur.

By the way, as described above, it is desirable to allocate all the data used in the rotation synchronization process to the local RAM 240H having a high access speed. However, since the storage area of the local RAM 240H is smaller than the storage capacity of the global RAM 240C, it is not realistic to allocate all the data to the local RAM 240H. Therefore, in consideration of the storage capacity of the local RAM 240H, at least a part of the data used in the rotation synchronization processing may be allocated to the local RAM 240H.

In this case, it is desirable to preferentially allocate the data having a short data length to the local RAM 240H among the plurality of data used in the rotation synchronization process. Further, among the plurality of data used in the time synchronization process, it is desirable to statically allocate the data having a long data length in preference to the global RAM 240C. By doing so, while the number of data allocated to the local RAM 240H increases, the number of data allocated to the global RAM 240C decreases, and the execution time of the time synchronization process and the rotation synchronization process in the control cycle can be shortened. can.

It is assumed that 16 1-bit length data, 2 8-bit length data, and 2 16-bit length data are accessed in the time synchronization process and the rotation synchronization process executed in the control cycle. Further, in this assumption, it is assumed that the storage areas of the global RAM 240C and the local RAM 240H that can be used in the time synchronization processing and the rotation synchronization processing are 4 bytes (32 bits), respectively. Further, it is assumed that the access speed of the global RAM 240C is 10 cycles based on the operating clock and the access speed of the local RAM 240H is 1 cycle based on the operating clock.

As shown in FIG. 9, 16 1-bit length data and 2 8-bit length data are assigned to the global RAM 240C, respectively, and 2 16-bit length data are assigned to the local RAM 240H. think of. In this case, the access time to the global RAM 240C is (16 + 2) × 10 = 180 [cycles]. Further, the access time to the local RAM 240H is 2 × 1 = 2 [cycle]. Therefore, the access time to the RAM is 180 + 2 = 182 [cycles].

On the other hand, as shown in FIG. 10, two 16-bit length data are allocated to the global RAM 240C, and 16 1-bit length data and two 8-bit length data are allocated to the local RAM 240H. Consider the case. In this case, the access time to the global RAM 240C is 2 × 10 = 20 [cycles]. The access time to the local RAM 240H is (16 + 2) × 1 = 18 [cycles]. Therefore, the access time to the RAM is 20 + 18 = 38 [cycles].

In this way, by preferentially allocating data with a short data length to the local RAM 240H with a high access speed and allocating data with a long data length to the global RAM 240C with a low access speed, from FIGS. 9 and 10. As you can see, a lot of data can be allocated to the local RAM 240H. As a result, as described above, the access time to the RAM is reduced from 182 [cycles] to 38 [cycles], and the execution time of the time synchronization process and the rotation synchronization process in the control cycle is shortened.

Then, by preferentially allocating the data having a short bit length among the plurality of data used in the rotation synchronization process to the local RAM 240H having a high access speed, the upper limit of the calculation load is reduced as shown in FIG. be able to. Further, as shown in FIG. 11, by preferentially allocating the data having a long bit length among the plurality of data used in the time synchronization process to the global RAM 240C having a low access speed, the entire calculation load can be reduced. Can be done.

It should be noted that those skilled in the art may omit some of the technical ideas of the above-mentioned embodiments, combine some of them as appropriate, replace some of them with well-known techniques, and further use well-known techniques. It will be easy to understand that the combination can create new embodiments.

As an example, the engine 100 is not limited to a gasoline engine, but may be a diesel engine. Further, the bit length of the data is not limited to 1 bit, 8 bits and 16 bits, and may be any number of bits. Further, the time synchronization process is not limited to the control of the VTC 200, and may be another process such as failure diagnosis, and the rotation synchronization process is not limited to the fuel injection process and the ignition control process, but is another process. You may.

100 engine (internal combustion engine)
220 Crank angle sensor (rotation sensor)
230 Cam angle sensor (rotation sensor)
240 Electronic control device (control device)
240C global RAM (first volatile memory)
240H local RAM (second volatile memory)

Claims (6)

It is equipped with a first volatile memory and a second volatile memory whose access speed is faster than that of the first volatile memory, and performs time synchronization processing synchronized with time and rotation synchronization processing synchronized with the rotation of the internal combustion engine, respectively. It is the control device of the internal combustion engine that is executed.
At least a part of the data used in the rotation synchronization process is statically allocated to the second volatile memory.
Internal combustion engine control device. The data statically allocated to the second volatile memory is set in the application program.
The control device for an internal combustion engine according to claim 1. Of the plurality of data used in the rotation synchronization process, the data having a short data length is preferentially allocated to the second volatile memory.
The control device for an internal combustion engine according to claim 1 or 2. Of the plurality of data used in the time synchronization process, the data having a long data length is statically allocated in preference to the first volatile memory.
The control device for an internal combustion engine according to any one of claims 1 to 3. A rotation sensor that outputs a pulse signal proportional to the rotation speed of the internal combustion engine is further provided.
The rotation synchronization process is executed in response to the pulse signal output from the rotation sensor.
The control device for an internal combustion engine according to any one of claims 1 to 4. The rotation synchronization process is at least one of a fuel injection process and an ignition control process.
The control device for an internal combustion engine according to any one of claims 1 to 5.

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