JPH05324721A - Memory data search method - Google Patents

Abstract

(57) [Summary] [Purpose] To shorten the data retrieval time from the memory map table. [Configuration] The detected value N of the engine speed of the internal combustion engine is the origin
When the value of the grid exceeds the detection value N _X compared with the value of the grid every 4 pieces from (X, X), the value of the grid read one by one in the same direction from the grid one time before. And the detected value are compared, and when the value of the grid is greater than or equal to the detected value, the grid is determined as the grid for data search. The grid is similarly determined for the basic fuel injection amount T _P , and the data at the intersection (A, B) of the determined grids is searched. The data of the grid point one smaller than that may also be searched for the interpolation calculation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for retrieving data stored in a map table of a memory.

[0002]

2. Description of the Related Art In recent years, various controls in vehicles have been executed by microcomputers. For example, in the case of control of an internal combustion engine, data such as the basic ignition timing (advance value) is stored in a memory in advance with the engine speed N and the basic fuel injection amount T _P representing the load as parameters, and the engine speed is increased. Based on the speed N and the basic fuel injection amount T _P , the basic ignition timing data is retrieved from the memory, the ignition timing is set by appropriately correcting the data, and the ignition timing is controlled.
(See JP-A-62-38854, etc.).

By the way, the data is stored on a lattice point where the parameter axes of the engine speed N and the basic fuel injection amount T _P intersect. The numerical value of the fuel injection amount T _P is set to a close interval in a range where control is highly required, and a rough interval in a range where it is not so necessary. When searching for data corresponding to the detected engine speed N or basic fuel injection amount T _P , the values of the grid axis of the engine speed N are read in order from the smallest value to determine the corresponding grid axis. Similarly, for the basic fuel injection amount T _P , the lattice axes are determined in the same manner, and the data stored at the points where the lattice axes intersect are searched.

However, in such a search method, the origin is
In the case of searching data on the lattice axis apart from the (reading start point), it takes time to determine the lattice axis, which leads to an increase in the search processing time as a whole. In particular, when the above-mentioned search of the basic ignition timing is performed in synchronization with the engine rotation (at every predetermined crank angle), the search cycle is shortened in the high rotation speed region, while the grid of the engine rotation speed N is reduced. Since the time required to determine the axis is long, the arithmetic processing is limited, and as a result, it is difficult to increase the number of stored data and perform highly accurate control.

Further, when the basic ignition timing search or the like is executed in a background job, other computations performed in synchronization with the rotation increase when the engine speed increases, and the ignition timing followability during transient operation is improved. It was getting worse. The present invention has been made in view of such conventional problems,
An object of the present invention is to provide a data search method for a memory, which can keep the search processing time within a predetermined time and can cope with an increase in the number of stored data.

[0006]

For this reason, the memory data retrieval method according to the present invention reads the numerical values of the parameters in which the data are stored from the smaller value to the larger value or in the opposite direction by reading every plural numbers. By comparing with the value of the predetermined parameter, when it is determined that the value of the predetermined parameter has been passed, the parameters are specified by reading one by one in the same direction as the reading direction from the numerical parameter read one time before. , A method of retrieving data corresponding to the specified parameter.

Further, another data retrieval method according to the present invention reads the numerical values of the parameters in which the data are stored from the smaller value to the larger value or in the opposite direction, and reads a plurality of values to obtain the value of the predetermined parameter. In comparison, when it is determined that the value of the predetermined parameter has been passed, the parameters are read one by one in the direction opposite to the reading direction, the parameters are specified, and the data corresponding to the specified parameters is searched. ..

Here, the parameter is the engine rotation speed of the internal combustion engine, and may be used to search data at intervals synchronized with the engine rotation, or may be used to search data in a background job. ..

[0009]

Operation: By reading a plurality of parameter values in a direction in which the value increases or decreases, the parameter values are roughly approximated to the desired parameters, and when it is determined that the predetermined parameters have been passed, the parameter is read one time before. In order to determine the predetermined parameter by reading the value of the parameter one by one in the same direction as the reading direction from the numerical value of the parameter or in the opposite direction from the determined position, the number of readings until the determination is determined. The number of stored data can be increased because it can be suppressed to the number of times or less and the increase of the search processing time can be prevented. In addition, control followability during transient operation can also be improved.

In particular, when the present invention is applied to a data retrieval at an interval synchronized with the engine revolution using the engine rotation speed of the internal combustion engine as a parameter, when the retrieval is carried out in a short period in a high rotation speed region. However, the search processing can be completed within the cycle.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1 showing the configuration of one embodiment, air is drawn into an internal combustion engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4 and an intake manifold 5. The intake duct 3 is provided with an air flow meter 6, and the throttle chamber 4 is provided with a throttle valve 7 interlocked with an accelerator pedal (not shown) to control the intake air flow rate Q. The intake manifold 5 is provided with an electromagnetic fuel injection valve 8 for each cylinder, and injects fuel into the intake manifold 5 which is pressure-fed from a fuel pump (not shown) and is controlled to a predetermined pressure by a pressure regulator. Further, an O ₂ sensor 10 for detecting the air-fuel ratio of the air-fuel mixture supplied to the engine by detecting the oxygen concentration in the exhaust gas is interposed in the exhaust passage 9.

The control of the fuel injection amount is performed in the control unit 11 with a built-in microcomputer as follows. That is, the intake air flow rate Q detected by the air flow meter 6 calculates the basic fuel injection quantity T _P from the engine speed N calculated on the basis of a signal from the crank angle sensor 12, the basic fuel injection quantity T _P The water temperature sensor 13
Correction by the cooling water temperature T _W detected by the battery 14 and the voltage of the battery 14, and further in a predetermined low and medium load region, air-fuel ratio feedback correction based on the air-fuel ratio detected by the O ₂ sensor 10 is performed to finally make a final correction. Set the fuel injection amount T _I ,
By outputting a drive pulse signal having a pulse width corresponding to this fuel injection amount T _I to the fuel injection valve 8 in synchronization with the engine rotation, a required amount of fuel is injected and supplied to the engine 1. There is.

Further, each cylinder of the engine 1 is provided with an ignition plug 15, to which a voltage generated by an ignition coil is applied, whereby spark ignition is performed to ignite and burn the air-fuel mixture. .. Here, the ignition timing (ignition advance value) A
The control of the DV is performed by the control unit 11. That is, the control unit 11 corresponds to the operating state from the map table stored in the ROM (memory) 11a for each of a plurality of operating regions divided by the basic fuel injection amount T _P and the engine rotation speed N. Basic ignition timing AD
V ₀ is searched, and the ignition signal ADV is output at the ignition timing set by correcting the basic ignition timing ADV ₀ by the water temperature or performing feedback correction using a knock sensor (not shown) in a region where knocking is likely to occur. Control the ignition timing.

Here, the data retrieval of the basic ignition timing ADV ₀ is performed according to the flow chart shown in FIG.
First, a search is made for a grid having one parameter, the engine speed N. First, after setting the head address of the N grid to X, the value of X is updated with the address obtained by adding 4 to this (S
1, S2).

Then, the current engine speed N and the above X
Address is compared with the value N _X N-grating in the, if an N ≧ N _X, after updating by 4 adds the address of X returns to S2, compares again N (S3). When N _X > N for the first time in the comparison of S3, the address of X is updated by a value obtained by subtracting 3 (S4), and the current engine speed N is compared with the value of the address of X. (S5).

If N ≧ N _X , then _X in S6
The address of is added by 1 and updated, and then compared with N again. When N _X > N for the first time in the comparison of S5, the address of X at this time is set to A (S7). Next, the search for the lattice of the other parameter, the basic fuel injection amount T _P , is performed in exactly the same manner as the search for the N lattice.
(S8 to S14), the corresponding address of X is set to B.

Then, the basic ignition timing ADV ₀ stored at the point where the N grid and the T _P grid at the addresses set in A and B intersect is retrieved (S15). For simplification, this search value may be used as it is, but in the case of obtaining more accurate data by interpolation, each grid of the addresses set in the above A and B and an address one smaller than these grids are used. The basic ignition timing ADV ₀ stored in the remaining 3 grid points of the 4 grid points intersecting with each grid is searched, and the data calculated using the known interpolation calculation method is used (S16; see FIG. 3). ..

According to such a retrieval method, the value of each lattice is read every four from the smallest, and after roughly approaching the detected value, the process goes back to detect the maximum of three at a fine interval. Since the grid corresponding to the value can be determined, the maximum processing time required for the search can be significantly shortened. For this reason, in the case where the search is performed in rotation synchronization, the data search cycle becomes short in the high-speed region of the engine rotation speed N, but the determination of the N grid can be greatly shortened, and there is more room for the search. Since the search execution opportunities are increased even in the case of performing the above, it is possible to have a margin even in the high speed range, and it is possible to improve the control accuracy during the transient operation. Further, it becomes possible to increase the data amount, particularly the data amount in the high speed range, and perform more precise control.

In the present embodiment, the value of the grid of each parameter is read from the smallest value to the largest value, but it may be read from the largest value to the smallest value, which is particularly high speed. When control is performed so that the frequency of data search in the high-speed range is higher than that in the low-medium speed range, the maximum search processing time can be further shortened by reading from the high-speed side to the low-speed side. Can be achieved.

FIG. 4 shows a flowchart of a data search method according to another embodiment of the present invention. That is, in the above-described embodiment, the method is to go back once after passing a predetermined grid and then read the values of the grid one by one again in the same direction.
In the present embodiment, when passing through a predetermined grid, the values of the grid are read one by one in the opposite direction, and the corresponding grid is determined.

Therefore, the part different from FIG.
At S15 and S20 to S21, the current engine speed N or the basic fuel injection amount T _{P is} decreased while the grid address is decreased by one.
When the current value is greater than or equal to the grid value, the grid is determined as the grid for searching the data. Further, when performing the interpolation calculation, the data of the remaining three grid points where the determined grid and the grid of the address one larger than these grids intersect are searched for and the interpolation calculation is performed (see FIG. 5). ..

[0022]

As described above, according to the present invention, a parameter for searching data can be determined in a short time, which leads to increase of data amount and improvement of control accuracy. Is. Further, when the parameter is the rotation speed of the internal combustion engine, in the case where the search is performed in synchronization with the rotation speed, even if the search cycle is shortened in the high speed range, the search time can be shortened to allow a margin. Since the number of search opportunities is increased by shortening the calculation time of the rotation synchronization, there is still a margin, and the accuracy of control using the search result during transient operation can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a hardware configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a data search routine of the above embodiment.

FIG. 3 is a diagram showing data used for interpolation calculation of data according to the embodiment.

FIG. 4 is a flowchart showing a data search routine according to another embodiment of the present invention.

FIG. 5 is a diagram showing data used for interpolation calculation of data according to the embodiment.

[Explanation of symbols]

 11 Microcomputer 11a ROM

Claims (3)

[Claims] 1. A method of retrieving data corresponding to a value of a predetermined parameter from a map table of a memory in which data corresponding to each numerical value of a parameter set at irregular intervals is stored. The numerical value of the parameter is read from the smaller one to the larger one or in the opposite direction at a plurality of intervals and compared with the value of the predetermined parameter.
At the time when it is determined that the value of the predetermined parameter has been passed, one by one is read from the numerical parameter read one time before in the same direction as the reading direction to specify the parameter, and the data corresponding to the specified parameter is read. A method for retrieving data in a memory, characterized by: 2. A method for retrieving data corresponding to a value of a predetermined parameter from a map table of a memory in which data is stored corresponding to respective numerical values of parameters set at irregular intervals, wherein the data is stored. The numerical value of the parameter is read from the smaller one to the larger one or in the opposite direction at a plurality of intervals and compared with the value of the predetermined parameter.
When it is determined that the value of the predetermined parameter has been passed, one by one is read in a direction opposite to the reading direction to specify a parameter, and data corresponding to the specified parameter is searched for. Data search method. 3. The data retrieval method for a memory according to claim 1, wherein the parameter is an engine speed of an internal combustion engine.