JPH0333915B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine control device equipped with a digital processor that calculates fuel injection amount and the like.

[Prior Art and Problems to be Solved by the Invention] In a conventional engine control device equipped with a digital processor, the engine rotation speed is stored in a RAM storage section as 2-byte (16-bit) data.
Reading data from RAM or ROM to the CPU and calculations in the CPU are performed in units of 1 byte (8 bits), so 2 bytes of data are sent to the CPU.
When reading or calculating, the number of steps in the program increases, which is disadvantageous for a control device where the number of steps in the entire program is limited. Furthermore, when the engine rotation speed is stored as 1-byte data, the accuracy of the engine rotation speed decreases, causing problems in calculating the fuel injection amount. for example
When the engine speed of 6000r.pm is displayed in 1 byte, the lowest bit (LSB) is 25r.pm (≒
^6000/28 ), whereas the LSB needs to be around 3.125 rpm to calculate the fuel injection amount, etc.

The purpose of the present invention is to significantly reduce the number of program steps for reading and calculating the engine rotation speed as a whole for the control device, and to prevent problems in the calculation accuracy of control variables calculated based on the engine rotation speed. The objective is to provide an engine control device that does not require any engine control equipment.

[Means for Solving the Problems] In order to achieve this object, the present invention employs the following means.

That is, the engine control device of the present invention controls the output engine by processing the engine rotational speed data detected from the output engine using a digital processor that uses a predetermined number of bits as a calculation unit, and outputting the result. An engine control device comprising: storage means for storing the detected engine rotational speed data with an accuracy of both the predetermined number of bits and a number of bits greater than the predetermined number of bits; and an accuracy required for various types of control of the output engine. The control means selects either engine rotational speed data stored with a predetermined number of bits or engine rotational speed data stored with a larger number of bits than the predetermined number of bits, and uses the same for each control. It is characterized by having the following.

[Function] The engine control device of the present invention stores the rotational speed of the output engine with two accuracies. That is, low-precision storage with a predetermined number of bits and high-precision storage with a larger number of bits.

The control means uses engine rotational speed data stored in a number of bits larger than a predetermined number of bits when high accuracy is required in various types of control. On the other hand, if low accuracy is acceptable, engine rotational speed data stored with a predetermined number of bits is used.

As a result, for control requiring high accuracy, highly accurate data (for example, 2-byte data) out of the stored engine rotational speed data is used as before.

However, in the case of control that requires low precision, low precision data (for example, 1-byte data) expressed by a predetermined number of bits is used. When using low-precision data, compared to using high-precision data, that is, data with a larger number of bits (e.g., 11 bits, 16 bits) than a predetermined number of bits (e.g., 8 bits), The number of processing steps on the digital processor side for reading and calculating can be extremely small.

For example, an 8-bit digital processor
Consider the case where a CPU is used. Inside the main routine executed by this CPU, a large number of low-precision calculation processes are performed in one control cycle, such as fuel cutoff, acceleration increase, high load increase, or execution timing judgment such as ignition timing acceleration advance. exist.

In order to determine the execution timing of each control, consider reading the engine rotational speed data to the CPU and simply comparing that value with another value (determination value).

In the case of highly accurate 2-byte engine speed data, the CPU must process an instruction code of 6 bytes (steps) in total, 3 bytes for read operation and 3 bytes for comparison operation, in one judgment.

However, in the case of low-accuracy 1-byte engine speed data, 2 bytes are used for the read operation and 2 bytes are used for the comparison operation.
The instruction code consists of a total of 4 bytes (steps).

In addition to the above-mentioned numerical comparison, during the process of determining the execution timing, it may be necessary to calculate Q/NE using the intake air amount (Q) and engine rotational speed (NE). . In such a case, Q and
When calculating with 2-byte data (2 bytes/2 bytes), 70 to 100 bytes (step)
Some processing is required. However, if Q is 2-byte data but NE is 1-byte data, the number of steps is extremely small, and only 2-byte steps are required.

Therefore, when using 1-byte data for calculations that occur many times within one control cycle and can be performed even with low precision, compared to using 2-byte data, it usually takes several tens of bytes or more. The number of steps is reduced by hundreds of bytes.

[Example] Embodiments of the present invention will be described with reference to the drawings.

To roughly explain the entire electronically controlled fuel injection engine to which the present invention is applied in FIG. The flow rate is controlled by , and then supplied to the combustion chamber 9 of the engine body 8 via the surge tank 5 , intake pipe 6 , and intake valve 7 . The air-fuel mixture combusted in the combustion chamber 9 is released as exhaust gas through an exhaust valve 10 and an exhaust branch pipe 11. An electromagnetic fuel injection valve 14 is provided in the intake pipe 6 corresponding to each combustion chamber 9. The electronic control device 15 includes a throttle switch 16 that detects when the throttle valve 2 is fully closed, a water temperature sensor 18 that is attached to the water jacket 17 of the engine body 8, and an intake pipe pressure sensor that is installed in the surge tank 5 and that is related to the intake air flow rate. a crank angle sensor 23 that detects the rotation angle of the distributor shaft coupled to the crankshaft to detect the rotation angle of the crankshaft coupled to the piston 21 via the connecting rod 22; An air-fuel ratio sensor 24 that is provided in the exhaust branch pipe 11 and detects the oxygen concentration in exhaust gas, and a vehicle speed sensor 25
Receives input signals from etc. The rotation angle sensor 23 is
It includes a section 26 that generates one pulse per revolution of the crankshaft and a section 27 that generates a pulse every predetermined crank angle, for example every 30 degrees. Fuel is force-fed from a fuel tank 30 to the fuel injection valve 14 via a fuel passage 29 by a fuel pump 31.

The electronic control unit 15 calculates the fuel injection amount and fuel injection timing based on various input signals, sends a fuel injection pulse to the fuel injection valve 14, calculates the ignition timing, and sends a signal to the ignition coil 32. The secondary current of the ignition coil 32 is sent to a distributor 33. Note that the injection valve 14 is controlled by an electronic control device 15.
It remains open only while receiving pulses from.

FIG. 2 is a block diagram of the inside of the electronic control unit 15. As an 8-bit digital processor
CPU (Central Processing Unit) 35, ROM (Read Only Memory) 36, RAM (Direct Access Memory)
37, C-RAM (complementary RAM) 38, input interface 39, and input/output interface 4
0 are connected to each other via a bus 41. C
- The RAM 38 is supplied with a predetermined amount of power and can retain its memory even when the engine is stopped. The input interface 39 is A/D (analog/digital)
It has a built-in converter, and the analog outputs of the water temperature sensor 18 and pressure sensor 19 are sent to the input interface 39. Throttle switch 16,
and crank angle sensor 23, air-fuel ratio sensor 2
4, and the outputs of the vehicle speed sensor 25 are sent to an input/output interface 40, and electrical signals to the fuel injection valve 14 and the ignition coil 32 are sent from the input/output interface 40.

FIG. 3 is a flowchart of a program that detects the engine rotational speed and stores it in the first and second storage sections A1 and A2 of the RAM 37. This program is executed in conjunction with the generation of a 30° crank angle pulse. In step 46, the current time tn is detected and stored. In step 47, the elapsed time Δt from the previous time tn-1 is calculated. In step 48, the engine rotational speed R is calculated from R=C/Δt. However, C is a constant (C=30°/360°). R=C/Δt is 2
Calculated in bytes. In step 49, the engine rotational speed R is stored in the 2-byte first storage section A1. The first memory section A1 has 16 bits in total, but the engine rotational speed N can be represented with a sufficiently high precision if it has 11 bits. For example, if the engine speed N of 6000 rpm is expressed in 11 bits, the LSB is approximately 3.125 rpm.
become. Therefore, it is not necessary to use all the bits in the first memory section A1. Step 5
0, a value R/2 ⁿ is calculated by shifting the value in the first storage unit A1 to the right n times. For example, when the maximum engine rotational speed is represented by 11 bits in the first storage section A1, n=3. As a result, all the engine rotational speeds stored in the first storage section A1 can be converted into 8-bit, ie, 1-byte, representation. n is the number of bits representing the maximum engine rotational speed -8, is a natural number in the range of 1 to 8, and is not limited to n=3. In step 51, R/2 ⁿ is stored in the 1-byte second storage section A2. In this way, the engine rotation speed displayed in 2 bytes is stored in the first storage section A1, and the engine rotation speed displayed in 1 byte is stored in the second storage section A2. In this way, the processing of this program ends.

In order to calculate the fuel injection amount, which requires high precision, and to control the idle speed, which is executed by a program (not shown), a highly accurate engine speed (approx.
3.125rpm) is required. Therefore, in these cases, the engine rotational speed data is read from the first storage section A1. In addition, for fuel cutoff or acceleration increase control that does not require high precision and is executed by a program (not shown), a low precision engine speed (approximately 25 rpm) is sufficient; therefore, in these cases, the second Read engine rotational speed data from storage section A2. When using such low-precision engine rotation speed data (8 bits), compared to using high-precision engine rotation speed data, that is, 11-bit data, the CPU needs to perform calculations in 8-bit units.
The number of processing steps on the 35 side is extremely small.

That is, within the main routine executed by the 8-bit CPU 35, low-accuracy judgments such as execution timing judgments such as fuel cutoff, acceleration increase, high load increase, or ignition timing acceleration advance are performed in one control cycle. There are many calculation processes.

In order to determine the execution timing of each control, the CPU 35 reads engine rotation speed data,
Consider a case where that value is simply compared with another value (judgment value).

In the case of highly accurate 11-bit engine speed data, the data is treated as 2-byte data,
One judgment requires processing of a total of 6 bytes (steps), 3 bytes (steps) for the read operation and 3 bytes (steps) for the comparison operation. However, in the case of low-precision 8-bit engine rotational speed data, a total of 4 bytes (steps), 2 bytes (steps) for the read operation and 2 bytes (steps) for the comparison operation, are required.

Additionally, in the process of determining execution timing, it may be necessary to calculate Q/NE using the intake air amount (Q) and engine rotational speed (NE) before the numerical comparison described above. . In such a case, Q
and NE are both 70 to 100 bytes (step) when calculating with 2 bytes of data (2 bytes/2 bytes).
Some processing is required. However, if Q is 2 bytes (9 bits to 16 bits) data but NE is 8 bits data, the number of steps is extremely small, and only 2 bytes are sufficient.

Therefore, when using 8-bit data for arithmetic operations that occur many times within one control cycle and can be performed with low precision, it usually takes several tens of bytes to 100 bytes compared to when using 11-bit data. The number of steps is reduced by hundreds of bytes.

Indeed, as shown in steps 50 and 51, an extra number of steps (approximately 5 bytes) are required to create engine rotation speed data stored in 8 bits from engine rotation speed data stored in 11 bits.
increases. However, this increase step occurs only once per control period. This is insignificant compared to the above reduction in the number of steps of several tens to hundreds of bytes.

As a result, the number of program steps in the overall control is significantly reduced.

[Effects of the Invention] As described above, the present invention stores engine rotational speed data both in a predetermined number of bits and in a number of bits larger than the predetermined number of bits. When highly accurate engine rotational speed data is required, engine rotational speed data stored with bits larger than a predetermined number of bits is selected and used for control. If low-accuracy engine rotation speed data is sufficient, engine rotation speed data stored with a predetermined number of bits is selected and used for control.

Therefore, in high-precision control, control processing is performed with the usual number of steps, but in control that requires less precision, control processing can be performed with a smaller number of steps, and the overall number of steps in digital processor processing is greatly reduced. .

As a result, the saved number of steps can be used for other control programs, thereby greatly improving the control ability of the entire control device.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of an electronically controlled engine to which the present invention is applied, FIG. 2 is a block diagram of the electronic control device shown in FIG. 1, and FIG. 3 is a flowchart of its program. 15...Electronic control unit, 23...Crank angle sensor, 35...CPU, 37...RAM.

Claims (1)

[Scope of Claims] 1. Engine control in which engine rotational speed data detected from an output engine is processed by a digital processor using a predetermined number of bits as a unit of calculation, and the output engine is controlled by outputting the result. The apparatus comprises a storage means for storing the detected engine rotational speed data with an accuracy of both the predetermined number of bits and a number of bits greater than the predetermined number of bits, and a storage means that stores the detected engine rotational speed data with an accuracy of both the predetermined number of bits and a number of bits larger than the predetermined number of bits, and a storage means that stores the detected engine rotation speed data with an accuracy of both the predetermined number of bits and a number of bits larger than the predetermined number of bits, and a storage means that stores the detected engine rotation speed data with an accuracy of both the predetermined number of bits and a number of bits larger than the predetermined number of bits, and the storage means corresponds to the accuracy required for various types of control of the output engine. control means for selecting either engine rotational speed data stored with a predetermined number of bits or engine rotational speed data stored with a larger number of bits than the predetermined number of bits for each control; An engine control device characterized by: 2. The engine rotation speed data stored with a predetermined number of bits is data obtained by shifting the engine rotation speed data stored with a larger number of bits than the predetermined number to the right by a predetermined number. An engine control device according to claim 1. 3. The engine according to claim 1 or 2, wherein the engine rotational speed data stored in a bit number larger than a predetermined number of bits is used for calculating the fuel injection amount or controlling the idle rotational speed. Control device. 4. Claim 1, characterized in that engine rotational speed data stored in a predetermined number of bits is used for fuel cutoff control or acceleration increase control.
The engine control device according to any one of Items 1 to 3. 5. The engine control device according to claim 2, wherein the predetermined number is three.