JP2006002647A - Atmospheric pressure detecting device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To well maintain operability of an engine by continuously detecting atmospheric pressure without putting a heavy treating load on an electronic control device in an engine of a plurality of cylinders for performing operation control by the electronic control device based on intake pipe pressure measured by a pressure detecting means without using an atmospheric pressure sensor, a throttle valve position sensor, or a crank angle sensor. <P>SOLUTION: The electronic control device 10 is equipped with a sampling means for sampling intake pipe pressure at predetermined intervals during operation of the engine 1 using a sensor 11 as the pressure detecting means provided for a branch pipe 21 of an intake manifold 2b, a fluctuating width measuring means for checking whether or not fluctuating width of the sampled intake pipe pressure value is within a predetermined allowable value for not less than predetermined consecutive times, an average value calculating means for calculating an average value when the fluctuating width is within the predetermined allowable value for not less than the predetermined consecutive times, and a storage means for storing the average value as the atmospheric pressure so as to detect the atmospheric pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for detecting atmospheric pressure for engine control, and more particularly, to detect atmospheric pressure continuously during engine operation in order to correct a fuel injection amount in accordance with fluctuations in atmospheric pressure. The present invention relates to a detection device.

  In the fuel injection system of an engine, when the atmospheric pressure (air density) changes, the intake air amount also changes. Therefore, the fuel injection amount is corrected in accordance with the changed atmospheric pressure in order to control to an appropriate air-fuel ratio. It will be necessary. In this case, an atmospheric pressure sensor is usually used for atmospheric pressure detection. However, additionally installing a relatively expensive atmospheric pressure sensor leads to an increase in the cost of the system.

  Therefore, as described in Japanese Patent Laid-Open No. 5-1615, a speed-identity system in which an engine control computer (electronic control device) calculates an intake air amount based on an engine rotation speed and an intake pipe pressure. Is a method that uses the intake pipe pressure sensor to turn on the key switch and sets the intake pipe pressure within a predetermined time to the approximate atmospheric pressure, and corrects the fuel injection amount based on this. ing. However, according to this method, since it is impossible to detect atmospheric pressure fluctuations due to changes in altitude during engine operation, etc., it is impossible to perform atmospheric pressure correction on the fuel injection amount. If it is large, there is a concern that the engine will stop.

  In response to this problem, Japanese Patent Application Laid-Open Nos. Hei 6-28666 and Japanese Patent Application Laid-Open No. 2003-176749 disclose that the fluctuation amount of the intake pipe pressure value detected by the intake pipe pressure sensor after starting the engine has a predetermined tolerance over a predetermined period. When the value is within the value, a method of storing the average value as the atmospheric pressure in the storage means of the electronic control device is proposed.

  This method continuously measures the intake pipe pressure even during engine operation, detects the portion where the fluctuation of the intake pipe pressure is small, calculates the average value, stores it as the atmospheric pressure, and increases the fuel injection amount. It is used for atmospheric pressure correction.

However, in the former method, an intake pipe pressure sensor is disposed at a collection portion of the intake manifold, and is generated in each of a plurality of cylinders as shown in the waveform diagram of FIG. 4 showing intake pipe pressure data. Since the falling due to the intake negative pressure appears continuously at different timings, there is no portion that matches the atmospheric pressure. Therefore, it is necessary to add various calculation means except when the throttle valve is fully opened in order to calculate the atmospheric pressure. The accuracy of the detected atmospheric pressure tends to be low, and the processing load increases, so that the electronic control device is predetermined. A processing capacity higher than the level is required. On the other hand, the latter method assumes a single-cylinder engine and also uses a crank angle sensor to detect the intake pipe pressure. And invites higher prices.
JP-A-5-1615 JP-A-6-28666 Japanese Patent Laid-Open No. 2003-176749

  The present invention is intended to solve the above-described problems. In a multi-cylinder engine operated by a speed-density method, the atmospheric pressure is reduced without imposing a large processing burden on the electronic control device. It is an object of the present invention to enable continuous detection so that the operability can be satisfactorily maintained without increasing the price.

  Therefore, the present invention relates to an atmospheric pressure detection device used in an engine whose operation is controlled by an electronic control unit based on an intake pipe pressure measured by a pressure detection unit. The pressure detection unit is installed in one branch pipe of an intake manifold. The sampling means for sampling the intake pipe pressure measured by the electronic control unit at a predetermined interval during engine operation, and the fluctuation range of the sampled intake pipe pressure value continuously within a predetermined allowable value for a predetermined number of times or more A fluctuation range measuring means for checking whether the fluctuation range is within a predetermined allowable value continuously for a predetermined number of times or more, and an average value calculating means for calculating an average value when the fluctuation range is within a predetermined allowable value. It is assumed that it comprises storage means for storing data.

  In this way, in the engine that employs the speed-dentity method for operation control, the intake pipe pressure sensor is preferably installed in one of the branch pipes at a portion that is not subject to intake interference by other cylinders of the intake manifold. Intake pipe pressure value area that is almost equal to atmospheric pressure because a waveform in which the fall of the intake pipe pressure during the intake stroke and the intake pipe pressure value almost equal to the atmospheric pressure during the non-intake stroke are alternately formed is formed. It is possible to indirectly detect the atmospheric pressure by using and to easily execute the atmospheric pressure correction. In addition, the processing of the intake pipe pressure and the procedure for calculating the atmospheric pressure from it are relatively simple and the processing burden is extremely light. Therefore, the manufacturing cost can be reduced due to the fact that the atmospheric pressure sensor, the throttle valve position sensor, and the crank angle sensor are unnecessary.

  In the above-described engine atmospheric pressure detection device, if the average value calculation means updates the atmospheric pressure data stored in the storage means every time the average value of the intake pipe pressure is calculated, the atmospheric pressure data is Since the coefficient in the air-fuel ratio control can be corrected based on this every time it is updated, the air-fuel ratio is optimally controlled by adjusting the fuel injection amount in response to this even when the environmental atmospheric pressure fluctuates. Therefore, it is easy to maintain good engine operability.

  Further, if the interval of detection of the intake pipe pressure by the sampling means is at least 1/1000 second or less, the detection accuracy of the flat portion that substantially matches the atmospheric pressure in the waveform of the intake pipe pressure will be sufficient, and the fuel It becomes easy to make the atmospheric pressure correction of injection appropriate.

  According to the present invention, the atmospheric pressure for engine control can be continuously detected without imposing a large processing burden on the electronic control unit, and the atmospheric pressure correction of the fuel injection amount is accurately performed based on this. Thus, the operability of the engine can be maintained satisfactorily.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a layout of an engine in which an atmospheric pressure detecting device for carrying out the present invention is disposed. The engine 1 is a two-cylinder two-cycle engine. The intake pipe 2 has an air cleaner 5 at the inlet, and includes a throttle body 2a in which a throttle valve 3 is disposed and an intake manifold 2b. The branch pipes 21 and 21 are connected to each cylinder of the engine 1. 4 is an exhaust pipe.

  In the present embodiment, a pressure sensor 11 as pressure detecting means is installed in one of the branch pipes 21, an engine speed sensor 12 is installed in the engine 1, and the electronic control device 10 is connected to the intake pipe. The speed-density method is used to calculate the intake air volume based on pressure and engine speed. The electronic control device 10 includes a CPU, a ROM, a RAM, an input / output circuit, and the like, and a simple and low-priced device that mainly performs basic operation control of the engine is sufficient. A program for operating as an atmospheric pressure detection device is input and stored.

  The pressure sensor 11 for detecting the intake pipe pressure is arranged at a position close to the engine 1 in the branch pipe 21 so as not to be affected by the negative intake pressure from the cylinder to which the other branch pipe is connected. . Therefore, as shown in FIG. 2, the intake pipe pressure value measured by the pressure sensor 11 is relatively flat with a single fall that occurs during the intake stroke and a fluctuation in the pressure value during the non-intake stroke per cycle of the engine 1. It is represented by a waveform consisting of various areas.

  Next, the principle of the present invention will be described with reference to the waveform diagram representing the intake pipe pressure data in FIG. The fall d in the waveform diagram of the intake pipe pressure measured using the pressure sensor 11 occurs during the intake stroke of the cylinder, that is, once per cycle, and between the fall d and the fall d in the next cycle. A flat portion f is formed during a non-intake stroke of a cylinder, and since the intake pipe pressure value in the flat portion f is almost equal to the atmospheric pressure, it is detected as an atmospheric pressure when a preset condition is met. Is.

  In other words, the electronic control device 10 samples the intake pipe pressure at a predetermined sampling interval y by the sampling means, and the fluctuation width of the sampled intake pipe pressure data by the fluctuation width measurement means is predetermined permissible for n times. It is checked whether or not the value is within the value x. When the value is within the allowable value x, the average value calculating means calculates the average value of the fluctuation range of the section and stores it in the storage means (RAM) as the atmospheric pressure. Is.

  Next, the operation of the electronic control device 10 in the atmospheric pressure detection device of the present embodiment will be described using the flowchart of FIG.

  When the engine is started, the intake pipe pressure detected by the pressure sensor 11 is sampled at a predetermined interval y by the sampling means (A1). Although the sampling interval y is set between several hundreds μs to several ms, the fluctuation range of the intake pipe pressure in the flat portion f can be detected with certainty. However, the engine 1 is a 2- to 4-cylinder gasoline engine and is electronic. When the expression control device 10 has a general processing speed and processing capability, the flat portion f can be detected with high accuracy if y = 1 ms (1/1000 second) or less.

  Then, the fluctuation range measuring means checks whether or not the fluctuation ranges are all within the allowable value x in the sampled n latest intake pipe pressure values (A2). If this is within the allowable value x, the average value calculating means calculates the average value of the n intake pipe pressures (A3), updates the atmospheric pressure data stored in the RAM as the storage means (A4), If there is a fluctuation range equal to or larger than the value x, the procedures (A3) and (A4) are not performed, and the procedure from (A1) is repeated.

  Since the electronic control device 10 has the fuel injection control function of the engine 1, the coefficient in the calculation formula of the fuel injection amount is corrected so that the optimum air-fuel ratio is obtained based on the updated atmospheric pressure. .

  As described above, the intake pipe pressure sensor is arranged in one of the branch pipes of the intake manifold that is not easily affected by the intake negative pressure of other cylinders, and the flat portion that substantially matches the atmospheric pressure is used in the intake pipe pressure data. According to the present embodiment, which can be easily detected, the atmospheric pressure can be continuously detected after starting the engine without imposing an excessive processing burden on the electronic control device, and the engine operability can be reduced at a low cost. Can be maintained well.

The layout which shows embodiment of this invention. The wave form diagram of the intake pipe pressure detected with the pressure sensor of FIG. The flowchart explaining the effect | action of the electronic control apparatus of FIG. The wave form diagram of the intake pipe pressure detected by the pressure sensor in the conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine, 2b Intake manifold, 10 Electronic control unit, 11 Pressure sensor, 12 Engine speed sensor, 21 Branch pipe

Claims (3)

An atmospheric pressure detection device used for an engine in which an electronic control device performs operation control based on an intake pipe pressure measured by a pressure detection means,
The pressure detecting means is installed in one branch pipe of the intake manifold,
The electronic control device includes sampling means for sampling the measured intake pipe pressure at predetermined intervals during engine operation, and the fluctuation range of the sampled intake pipe pressure value is continuously within a predetermined allowable value for a predetermined number of times or more. Fluctuation range measuring means for checking whether or not there is, average value calculating means for calculating an average value when the fluctuation range is within a predetermined allowable value continuously for the predetermined number of times or more, and calculating the calculated average value Storage means for storing as barometric pressure data,
An atmospheric pressure detection device for an engine.   2. The engine atmospheric pressure detection apparatus according to claim 1, wherein the average value calculating means updates atmospheric pressure data stored in the storage means every time an average value is calculated. 3. The engine atmospheric pressure detection device according to claim 1, wherein an interval of detection of the intake pipe pressure by the sampling means is at least 1/1000 second or less. 4.

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