JPH0361643A - Atmospheric pressure correction for engine - Google Patents

Abstract

PURPOSE:To surely improve the restart performance of an engine by constituting a flow rate control valve in a bypass passage of a throttle valve so as to be opened when the revolution speed on the stop of an engine reduces below the set revolution speed. CONSTITUTION:When the number of revolution reduces for the stop of an engine 1, the intake pressure on the downstream side of a throttle valve 12 gradually increases to the atmospheric pressure line. ln this case, if the engine revolution speed reduces lower than a set revolution speed, a flow rate control valve 11 is opened immediately for a certain time, and if the engine 1 stops, the valve is opened successively. Therefore, a bypass passage 15 is opened before the perfect stop of the engine 1, and the intake pressure on the downstream side of the throttle valve 12 is speedily increased to the atmospheric pressure line. Therefore, when the engine 1 restarts, the actual atmospheric pressure can be detected from the downstream side of the throttle valve 12 by a pressure sensor 7, and also the quantity of the fuel jetted out from a fuel injection valve 4 can be set to the quantity which is most proper for the air density and the engine state, and the restart performance of the engine 1 can be surely improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for correcting the atmospheric pressure of an engine, which can be suitably employed in automobiles and the like equipped with electronically controlled fuel injection devices.

[Prior Art] This type of engine is usually provided with a flow control valve in a bypass passage that bypasses a throttle valve.

The flow control valve is designed to be opened when an electrical load is applied to the engine by auxiliary equipment such as a near conditioner or fan motor, or for a certain period of time after the engine is started. It is designed to close when it is released or when a certain period of time has passed after the engine has started.

Furthermore, in engines that are not equipped with a dedicated pressure sensor for detecting atmospheric pressure, as prior art to the present invention, for example, as shown in Japanese Patent Application Laid-open No. 62-51733,
A pressure sensor that detects the intake pressure downstream of the throttle valve detects the atmospheric pressure at the time of starting the engine, and based on the detected value, the fuel injection amount at the time of starting is corrected according to the atmospheric pressure.

[Problems to be Solved by the Invention] However, with such a configuration, there is a relatively high possibility that the fuel injection amount will be inappropriate when the engine is restarted immediately after stopping. To be more specific, as shown in Figure 4, the intake pressure PM downstream of the throttle valve returns to the atmospheric pressure line as the engine rotation (indicated by the ignition pulse interval measurement counter) decreases, but the speed is relatively low. It is slow and reaches the atmospheric pressure line some time after the engine has completely stopped. Therefore, if the engine is restarted immediately after it has stopped, a pressure lower than the actual atmospheric pressure will be detected. the result,
At the time of restart, a smaller amount of fuel than the required injection amount is supplied to the combustion chamber, which deteriorates the restartability of the engine.

The present invention aims to eliminate such problems.

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

That is, the atmospheric pressure correction method for an engine according to the present invention detects the atmospheric pressure downstream of the throttle valve when the engine is started, and corrects the fuel injection amount at the time of starting based on the detected value. The atmospheric pressure correction method is characterized in that when the engine rotation when the engine is stopped is lower than a set rotation, a flow control valve provided in a bypass passage of the throttle valve is opened. do.

[Operation] According to this configuration, the flow control valve opens before the engine completely stops, and the upstream and downstream sides of the throttle valve communicate with each other via the bypass passage. Therefore, the atmosphere can be quickly introduced downstream of the throttle valve from the bypass passage, so that the pressure downstream of the throttle valve can be quickly returned to atmospheric pressure.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3.

An engine 1 schematically shown in FIG. 1 is installed in an automobile and includes an electronically controlled fuel injection device 2. The engine 1 shown schematically in FIG. The electronically controlled fuel injection device 2 includes a fuel injection valve 4 attached to an intake pipe 3 and an electronic control device 5 that controls the operation of the fuel injection valve 4.
The electronic control unit 5 adjusts the fuel supplied to the engine based on information from various sensors and the like.

The fuel injection valve 4 has a built-in electromagnetic coil, and when a fuel injection signal a is applied to the electromagnetic coil from the electronic control device 5, it injects fuel in an amount corresponding to the application time into the vicinity of the intake port. It looks like this.

The electronic control device 5 is composed of a microcomputer unit equipped with a central processing unit, a memory, an input/output interface, etc., and the input interface includes at least signals from the pressure sensor 7 and signals from the ignition coil 8. The ignition pulse signal C, the signal d from the starter switch 9, the signal e from the load switch 10, etc. are respectively input. The output interface outputs the fuel injection signal a, the control signal f to the flow rate control valve 11, and the like.

Further, this electronic control device 5 has the role of detecting atmospheric pressure from downstream of the throttle valve 12 using the pressure sensor 7 when starting the engine 1, and correcting the fuel injection amount at the time of starting based on the detected value. I am in charge. That is,
When the detected atmospheric pressure is high, the fuel injection amount is corrected to increase accordingly, and when the detected atmospheric pressure is low, the fuel injection amount is adjusted accordingly.

The pressure sensor 7 is configured to output an electrical signal proportional to the detected pressure, and is connected to a surge tank 14 via a filter 13. Load switch 1
0 is for detecting whether an electrical load or the like is applied to the engine 1 by a near conditioner or various auxiliary equipment. The flow control valve 11 opens and closes the bypass passage 15 of the throttle valve 12 to adjust the idle rotation speed to a predetermined target value, and is constituted by a solenoid valve.

Furthermore, the electronic control device 5 is also set with a program as schematically shown in FIG. First, on the premise that the starter switch 9 is closed, step 51 is performed.
Then, it is determined whether or not the engine 1 is stopped based on the ignition pulse signal C. If it is determined that the engine 1 is stopped, the process proceeds to step 57, and if it is determined that the engine 1 is starting, the process proceeds to step 52. Proceed to. In step 52, it is determined whether or not an electrical load is applied to the engine 1 based on the signal e from the load switch 10. If it is determined that an electrical load is applied, the process proceeds to step 57, and it is determined that no electrical load is applied. If so, proceed to step 53. Step 53
Then, after the pressure sensor 7 detects the atmospheric pressure from inside the surge tank 14, it is determined whether the engine 1 has not stopped for a certain period of time (30 seconds) or more, and if it has not stopped, then If it is determined that the engine 1 has definitely started, the process proceeds to step 58, and if it is determined that the engine 1 has been started for a certain period of time or more, the process proceeds to step 54.

In step 54, a certain period of time (
255 seconds), and if it is determined that it is within a certain period of time, the process proceeds to step 58, and if it is determined that the certain period of time has elapsed, the process proceeds to step 55. Step 55
Then, the engine rotation (E/G rotation) is the set rotation (200
It is determined from the ignition pulse signal C whether or not it exceeds the rpm), and if it is determined that it exceeds the engine speed, step 58
Proceed to Step 5 if it is determined that it is above or not.
Proceed to step 6. In step 56, the flow control valve VSV
A certain period of time (500ms) after valve 11 is opened (ON)
It is determined whether the time has elapsed or not. If it is determined that the time has not elapsed, the process proceeds to step 57, and if it is determined that the time has elapsed, the process proceeds to step 58. In step 57, the flow control valve VS
Open (ON) V11. In step 58, 5
Clear the 00m5 counter and proceed to step 59. In step 5, the flow control valve VSV 11 is closed (O
f'F). Note that the above control is repeatedly executed when the ignition switch is closed.

According to such a configuration, when the engine 1 is reliably started with no electrical load or the like applied to the engine 1, the flow rate control valve VSV 11 is closed. In addition, if the engine 1 stops within a certain short time after atmospheric pressure is taken in when starting the engine 1, and if the engine rotation when the engine 1 stops exceeds the set rotation, Since there is no need to update the atmospheric pressure immediately, the flow control valves VS, V
11 is closed.

On the other hand, as shown in FIG. 3, when the engine 1 is stopped and the engine rotation decreases, the intake pressure PM downstream of the throttle valve 12 gradually returns to the atmospheric pressure line. At that time, when the measurement counter between ignition pulses reaches the set value and the engine speed falls below the set speed, the flow control valve vsvil is immediately opened for a certain period of time, and if the engine 1 has completely stopped, it is opened continuously. will be excused.

Therefore, according to such a configuration, when the engine 1 stops, the bypass passage 15 is closed before the engine 1 stops completely.
is opened, the intake pressure downstream of the throttle valve 12 can be quickly returned to the atmospheric pressure line. As a result, when restarting the engine 1, the pressure sensor 7 can detect the actual atmospheric pressure downstream of the throttle valve 12, so the amount of fuel injected from the fuel injection valve 3 also depends on the air density and engine conditions. It will be the appropriate amount,
The restartability of the engine 1 can be reliably improved.

Further, since the flow rate control valve 11 is conventionally not used except for adjusting the idle rotation speed, this configuration allows the flow rate control valve 11 to be used effectively.
Furthermore, there is no need to add special equipment or complicate the control procedure.

Note that the present invention is applicable not only to detecting engine rotation using an ignition pulse but also to detecting engine rotation using a crank angle sensor or the like.

Further, the target rotation speed for opening the flow control valve when the engine is stopped is, of course, not limited to the values shown in the above embodiments.

Furthermore, the present invention is applicable not only to the case of using a flow control valve for idle speed control, but also to the case of using a flow control valve for increasing the idle of an electric machine load.

[Effects of the Invention] According to the present invention constructed as described above, when the engine is stopped, the pressure downstream of the throttle valve can be quickly returned to atmospheric pressure, so that when the engine is restarted, the fuel The supply amount can be appropriately adjusted according to the actual atmospheric pressure, and the restartability of the engine can be reliably improved.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a schematic overall configuration diagram, FIG. 2 is a flowchart diagram schematically showing a control procedure, and FIG. 3 is a control mode. It is a timing chart figure. FIG. 4 is a timing chart corresponding to FIG. 3 showing a conventional example. 1... Engine 4... Fuel injection valve 7... Pressure sensor 8... Ignition coil 11... Flow rate control valve 12... Throttle valve 15... Bypass passage

Claims (1)

[Claims] An atmospheric pressure correction method for an engine configured to detect atmospheric pressure from downstream of a throttle valve when starting the engine, and correct the fuel injection amount at starting based on the detected value, when the engine stops. 1. A method for correcting atmospheric pressure in an engine, comprising: opening a flow control valve provided in a bypass passage of the throttle valve when the engine rotation is lower than a set rotation.