JPS62245936A - Detecting and processing method for negative pressure - Google Patents

Abstract

PURPOSE:To detect wide-range pressure by one pressure sensor with high accuracy by making corrections so that the driving signal of an actuator has a signal value corresponding to actual negative pressure. CONSTITUTION:An electric signal (a) generated by the pressure sensor 2 connected to a suction path 1 as a negative pressure generation source by a negative pressure conduit 5 is sent to a signal processor 3, and consequently the driving signal (b) is sent to the actuator 4, thereby performing air-fuel ratio control. Then when an opening/closing valve 6 is opened with a valve opening signal (c) sent from the processor 3, air controlled by a contraction of area 7 is admitted into the conduit 5 and the negative pressure in the suction path 1 operates on the sensor 2 while reduced. Here, the signal (a) which is almost proportional to the negative pressure detected by the sensor 2 is sent to the processor 3, so the processors 3 is programmed previously so that when the negative pressure exceeds certain negative pressure P1, the valve opening signal (c) is generated. Thus, the valve 6 is opened when the negative pressure P1 is exceeded, thereby reducing the negative pressure to P2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative pressure detection processing method for a pressure cassette/sustainer that detects negative pressure and generates an electric signal to be sent to a signal processing device for driving an actuator, and is mainly used in automobiles. It is used to detect intake manifold pressure in engine air-fuel ratio control.

For example, when controlling the air-fuel ratio of a car engine,
One of the factors that determines the operating condition of an engine is the intake manifold pressure. As shown in the embodiment of the present invention in FIG. 1, the intake manifold pressure is determined by a pressure casing 7t, such as an aneroid type, semiconductor piezoresistive type, or capacitive type, which is temporarily connected to the intake path l of the engine.
2 to generate an electrical signal approximately proportional to the negative pressure (intake manifold pressure), which is input to the signal processing device t3 consisting of a microcomputer, which performs arithmetic processing to control the solenoid valve for air-fuel ratio control and the step motor. It is used to send a drive signal to the actuator 4, etc.

However, there is a relationship between the air flow ff1Q in the intake passage 1 and the pressure ΔP at that time: Q=C80C: flow coefficient, A: cross section of the intake passage m).

Since ΔP occurs in proportion to Q2, in the case of an automobile engine or the like where Q varies over a very wide range, the fluctuation range of ΔP is extremely large. For this reason, it is necessary to use a pressure chamber with an extremely wide dynamic range;
The drawback is that they generally have low accuracy. Furthermore, it has been attempted to share the dynamic range by using multiple pressure sensors, but this inevitably complicates the configuration.

The present invention solves the above-mentioned problems and
The aim is to provide a method that can detect pressures over a wide range with high precision.

The negative pressure detection processing method of the present invention reduces the negative pressure applied to the pressure cassette when the negative pressure detected by the pressure sensor exceeds a predetermined value, and inputs an electrical signal corresponding to the reduced negative pressure. The signal processing device is configured to perform correction processing so that the actuator drive signal has a signal value corresponding to the actual negative pressure.

Example The present invention σ) will be explained with reference to the drawings.

As explained briefly in 5, in FIG. From this, a drive signal is sent to the actuator 4 to perform air-fuel ratio control.

A thrust conduit 8 having an electromagnetically driven on-off valve 6 and a throttle 7 is connected to the negative pressure conduit 5 .

When the on-off valve 6 is opened by the valve-opening signal C sent from the signal processing device 3, air controlled by the throttle 7 is introduced into the negative pressure conduit 5.

Therefore, the negative pressure in the intake passage 1 is reduced and acts on the pressure sensor 2.

Intake path 1? The flowing air flow g#Q and the pressure ΔP generated thereby have a relationship according to the above equation.

The graph will look like curve B in Figure 2. Here, since an electric signal a that is almost proportional to the negative pressure detected by the pressure sensor 2 is sent to the signal processing device @3, the signal processing device is set in advance so that the valve opening signal C is generated when the negative pressure Plk is exceeded. A program is installed in @3, and when pt& is exceeded, the open/close valve 6 is opened to reduce the negative pressure kP2 acting on the pressure sensor 2. After the negative pressure exceeds Pl, Q-AP is
The graph looks like the A curve in Figure 2, and the 9 pressure ΔP corresponding to this human curve acts on the pressure sensor 2, and even when the intake passage 1 reaches the maximum negative pressure P3, there is no pressure in the pressure cassette/suction 2. Only the negative pressure P4, which is lower than that, acts. Therefore, although the intake manifold pressure in the intake passage 1 changes between atmospheric pressure Po and the maximum negative pressure P3, the pressure acting on the pressure casing 2 changes between Po and P3, The dynamic range of the pressure sensor 2 becomes narrower accordingly.

On the other hand, when the open valve compensation signal C is being issued, the electrical signal a has a signal value corresponding to a smaller air flow rate than the actual one, so the signal processing device! At step 113, a correction process is performed to generate a drive signal having a signal value corresponding to the actual air flow rate, that is, the actual negative pressure. In this correction process, data corresponding to graphs A and H in FIG. 2 are input and stored in the signal processing device 3 in advance. Difference with P3 (P3-
P4) and determines that the negative pressure in the intake path 1 is P3,
This is done by emitting a drive signal corresponding to the negative pressure P3.

When the negative pressure decreases to P2, the six on-off valves are closed to allow actual negative pressure to act on the pressure cell 2, and thereafter no correction processing is performed.

Note that the timing for reducing the negative pressure acting on the pressure sensor 2 is fixed and set when a constant negative pressure P1 is reached (the timing for reducing the negative pressure applied to the pressure sensor 2 is set at a fixed value depending on the operating status of the machine/engine). It is also possible to reduce the pressure when the pressure is reached.

According to the present invention, when the negative pressure acting on the pressure sensor exceeds a predetermined value, this negative pressure is reduced, so even if the fluctuation range of negative pressure is extremely large, a pressure sensor with a narrow dynamic range can be used. Accurate detection is possible using just one piece.

Further, since the reduced negative pressure is corrected to correspond to the actual negative pressure and the actuator is driven, appropriate feedback control can be performed without malfunction.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between air flow rate and negative pressure. 1... Intake path, 2... Pressure sensor, 3
... Signal processing device, 4 ... Actuator, 5 ... Negative pressure conduit, 6 ... Opening/closing valve, 8 ... Air conduit.

Claims (1)

[Claims] When the negative pressure detected by the pressure sensor exceeds a predetermined value, the negative pressure applied to the pressure sensor is reduced, and an actuator is activated in a signal processing device that receives an electric signal corresponding to the reduced negative pressure. A negative pressure detection processing method characterized by performing correction processing so that a drive signal has a signal value corresponding to an actual negative pressure.