JPH04241761A - Device for detecting intake air pressure of internal combustion engine - Google Patents

Abstract

PURPOSE:To promptly detect a change of intake air pressure based on a signal from a pressure sensor for detecting the intake air pressure at the time of quick acceleration or the like. CONSTITUTION:When a change amount of a throttle valve opening, calculated based on a signal from a throttle sensor 7, is less than a predetermined value, a switch 5 is switched to a side of a contact (a) by a microcomputer 6 to read a signal from a pressure sensor 1 through a low-pass filter 2 by removing an intake air pulsating component. When the change amount of the throttle valve opening is increased to the predetermined value or more, the switch 5 is switched to a side of a contact (b), and a signal with no response delay is obtained by directly reading the signal from the pressure sensor 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake pressure detection device for an internal combustion engine.

0002

2. Description of the Related Art There is a control device for an internal combustion engine that detects the pressure in the engine intake passage and controls the fuel injection amount, ignition timing, boost pressure, etc. in accordance with the detected pressure. Here, an intake pressure sensor is used to detect the intake pressure, but if the signal is used as it is, it contains an intake pulsation component, so the detection will depend on the level of the intake pulsation at which detection is performed. The results will be different, making it impossible to detect the average pressure necessary for calculating the fuel injection amount and the like.

[0003] Therefore, a low-pass filter is used to remove the intake pulsation component from the signal of the intake pressure sensor. However, when such a low-pass filter is used, even if the average pressure suddenly changes during sudden acceleration, etc., a large delay in response occurs, making it impossible to accurately detect the pressure change.

Therefore, as shown in Japanese Patent Publication No. 2-7410, a first low-pass filter and a second low-pass filter connected in series are used, and the output of the first low-pass filter is There is a device in which the intake pulsation component is removed and an average output without response delay is obtained by adding the difference between the output of the first low-pass filter and the output of the second low-pass filter.

[0005]

However, the device disclosed in the above-mentioned publication has a problem in that the circuit is large-scale due to the use of a subtraction circuit and an addition circuit, leading to an increase in cost. SUMMARY OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide an intake pressure detection device for an internal combustion engine that can be constructed at low cost using a relatively simple circuit.

[0006]

[Means for Solving the Problems] Therefore, the present invention provides the following (A) as an intake pressure detection device for an internal combustion engine that detects intake pressure based on a signal from a pressure sensor facing into an engine intake passage. ~(C) The configuration is such that the following are provided. (A) A filter that removes intake pulsation components from the signal from the pressure sensor. (B) A first path for reading the signal from the pressure sensor via the filter and a second path for reading the signal from the pressure sensor. A switching means (C) capable of switching between the first path and the first path; calculates the amount of change in the throttle valve opening based on the signal from the sensor that detects the throttle valve opening, and when the amount of change is less than a predetermined value, the first path is selected; is selected, and the following (D) to (F) are provided.

(D) A filter constituted by an integral circuit that removes intake pulsation components from the signal from the pressure sensor. (E) Switching means capable of switching the integral constant of the filter. (F) Detecting the throttle valve opening. The switching means is configured to calculate the amount of change in the throttle valve opening based on the signal from the sensor, increase the integral constant when the amount of change is less than a predetermined value, and decrease the integral constant when the amount of change is greater than or equal to the predetermined value. control means to control

[0008]

[Operation] In the above configuration, a throttle valve opening signal that can detect the acceleration state with good responsiveness is used, and based on the amount of change in the throttle valve opening, when the signal exceeds a predetermined value, the intake pressure changes. In this case, the signal from the pressure sensor is read without going through the filter, or with the integral constant of the integrating circuit that makes up the filter set small, so that there is no response delay. Get a signal.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the invention. A pressure sensor 1 faces into an engine intake passage (intake manifold) and outputs a voltage signal according to intake pressure.

A low pass filter (LPF) 2 removes an intake pulsation component, which is a low frequency component, from the signal of the pressure sensor 1. Here, a first path 3 for reading a signal from the pressure sensor 1 via a low-pass filter 2, and a first path 3 for reading a signal from the pressure sensor 1 through a low-pass filter 2;
A second path 4 is provided for directly reading signals from the second path, and these can be switched by a switch 5 as a switching means.

The switch 5 is switched by a signal from a microcomputer 6 as a control means, and selects the first path 3 at the a contact side and selects the second path 4 at the b contact side. The microcomputer 6 inputs a signal from a potentiometer-type throttle sensor 7 that outputs a voltage signal corresponding to the throttle valve opening, and inputs a signal from the pressure sensor 1 while switching the switch 5 according to the flow chart of FIG. 2, which will be described later. is read to detect the intake pressure, calculate the fuel injection amount Ti based on this, and output a drive pulse signal with a pulse width of this Ti to the fuel injection valve 8 at a predetermined timing synchronized with the engine rotation.

[0012] Instead of the throttle sensor 7, a sensor for detecting the amount of depression of the accelerator pedal may be provided, and the throttle valve opening may be indirectly detected by this sensor. Next, the flowchart in FIG. 2 will be explained. In step 1 (indicated as S1 in the figure; the same applies hereinafter), the throttle valve opening degree TVO is detected based on the signal from the throttle sensor 7, and the comparison with the previous detection value (TVO') (a certain period of time ago) is performed. As the difference, the amount of change in throttle valve opening ΔTVO=(TVO-TVO') is calculated.

In step 2, the amount of change ΔTVO in the throttle valve opening is compared with a predetermined value PS, and if ΔTVO≧PS, the process proceeds to step 3. In step 3, ΔTVO≧
It is determined whether a certain period of time has elapsed in the PS state, and until it has elapsed, the process proceeds to step 9 and the switch 5 is held at the a contact side, but when it has elapsed, the process proceeds to step 10 and the switch 5 is held at the b contact side. Switch to

When ΔTVO<PS, proceed to step 4, determine whether the switch 5 is currently on the b contact side, and select YES.
If so, proceed to step 5, and if NO, proceed to step 9 to hold the switch 5 on the a contact side. In step 5, it is determined whether ΔTVO≧PS last time,
If YES, the process proceeds to step 6 to set a delay time DEL to set the switch 5 to the a contact side, and then proceeds to step 10 to hold the switch 5 to the b contact side.

If the determination in step 5 is NO, the process proceeds to step 7, where the delay time DEL is decremented, and in the next step 8, the delay time DEL is compared with 0.
If DEL≠0, proceed to step 10 and switch switch 5.
is held on the b contact side, and if DEL=0, step 9
Go to and return switch 5 to the a contact side. In this way, the amount of change ΔTVO in the throttle valve opening is calculated based on the signal from the throttle sensor 7, and in principle, the amount of change ΔTVO is calculated based on the signal from the throttle sensor 7.
When TVO is less than a predetermined value PS, the switch 5 is switched to the a contact side to select the first path 3 in which the signal of the pressure sensor 1 is read through the low-pass filter 2, and when the TVO is greater than the predetermined value PS, the signal of the pressure sensor 1 is read. The second path 4, which directly reads the signal, is selected.

In step 11, the signal of the pressure sensor 1 is read from the selected path as described above. Then, in step 12, a predetermined calculation is performed to calculate the fuel injection amount, and in step 13, fuel injection is performed based on this. Therefore,
As shown in FIG. 3, in normal operating conditions, the average pressure is detected using the signal from which the intake pulsation component has been removed, which is the output of the low-pass filter 2, and various controls are performed. Using the signal of pressure sensor 1 as is,
That is, a signal that includes an intake pulsation component but has no response delay is used to promptly detect pressure changes and perform various controls.

FIG. 4 shows a second embodiment of the invention. In this example, in the first embodiment, an integrating circuit 9 consisting of a resistor R1 and a capacitor C1 and having a small integral constant is interposed in the second path 4. The other configurations are the same as the first embodiment. FIG. 5 shows the third embodiment of the present invention.
An example of this is shown.

In this example, the low-pass filter 2 is constituted by an integrating circuit consisting of a resistor R2 and a capacitor (C2 + C3), and the capacitors C2, C2 and C3 are connected in parallel to each other.
A normally closed switch 10 as a switching means is interposed on one of the capacitors C3 side. here,
By opening switch 10, capacitor C3
is separated, an integrating circuit is constructed from the resistor R2 and the capacitor C2, and the integral constant can be made small.
Therefore, the switch 10 constitutes an integral constant switching means.

The switch 10 is opened and closed by a signal from a microcomputer 6 as a control means. The microcomputer 6 inputs the signal from the throttle sensor 7, opens and closes the switch 10 as in the flowchart of FIG. perform calculation processing.

That is, the amount of change ΔTVO in the throttle valve opening is calculated based on the signal from the throttle sensor 7, and when the amount of change ΔTVO is less than a predetermined value PS, the switch 1 is
0 is closed and the integration constant of the low-pass filter 2 is increased, the signal of the pressure sensor 1 is read, and the predetermined value PS is read.
At this time, the signal from the pressure sensor 1 is read while the switch 10 is opened and the integral constant of the low-pass filter 2 is made small.

[0021] In this way, in normal operating conditions, the average pressure can be detected and various controls can be performed using a signal from which the intake pulsation component has been completely removed, and during sudden acceleration, etc. Using a signal that includes an intake pulsation component but with almost no response delay, pressure changes can be quickly detected and various controls can be performed.

[0022]

[Effects of the Invention] As explained above, according to the present invention, during sudden acceleration, etc., the signal from the pressure sensor is read without passing through the filter, or the integral constant of the integrating circuit constituting the filter is reduced. It is possible to obtain a signal with no response delay by reading the state, and furthermore, it is possible to achieve the effect that this can be realized with a relatively simple circuit at low cost.

[Brief explanation of the drawing]

[Figure 1] System diagram showing the first embodiment of the present invention

[
Figure 2: Flowchart showing control details

[Figure 3]
Signal waveform diagram

[Figure 4] System diagram showing the second embodiment of the present invention

[
Figure 5: System diagram showing the third embodiment of the present invention

[Explanation of symbols]

1 Pressure sensor 2 Low pass filter 3 First route 4 Second route 5 Switch 6. Microcomputer 7 Throttle sensor 10 Switch

Claims (2)

[Claims] 1. An intake pressure detection device for an internal combustion engine, which detects intake pressure based on a signal from a pressure sensor facing into an engine intake passage, wherein an intake pulsation component is removed from the signal from the pressure sensor. a filter, a switching means capable of switching between a first path for reading a signal from the pressure sensor via the filter and a second path for reading the signal from the pressure sensor, and detecting a throttle valve opening degree. The amount of change in the throttle valve opening is calculated based on the signal from the sensor, and the first path is selected when the amount of change is less than a predetermined value, and the second path is selected when the amount of change is greater than or equal to the predetermined value. An intake pressure detection device for an internal combustion engine, comprising: a control means for controlling the switching means. 2. An intake pressure detection device for an internal combustion engine that detects intake pressure based on a signal from a pressure sensor facing into an engine intake passage, the intake pulsation component being removed from the signal from the pressure sensor. The amount of change in the throttle valve opening is calculated based on a signal from a filter configured with an integrating circuit, a switching means capable of switching the integral constant of the filter, and a sensor that detects the throttle valve opening, and the amount of change is calculated based on a signal from a sensor that detects the throttle valve opening. an intake pressure detection device for an internal combustion engine, comprising: control means for controlling the switching means so as to increase the integral constant when is less than a predetermined value, and to decrease the integral constant when it is greater than or equal to a predetermined value. .