JPS58137727A - Pressure detector - Google Patents

Abstract

PURPOSE:To reduce the detection error near zero differential pressure, by determining a zero point on condition that an ignition switch is turned on and the number of revolutions of an engine is zero and using this zero point as a reference hereafter to detect a pressure. CONSTITUTION:A sample holding circuit S & H always connected to a battery B, and smapling and holding are performed if an ignition switch Igsw is turned on and the number of revolutions is zero. The output is connected to the inverted input terminal of a differential amplifier AMP, and a held voltage e0 is outputted. The output of a differential pressure sensor 10 is connected to the inverted input terminal of the differential amplifier AMP, and an output e1-e0=e2 is supplied from the differential amplifier AMP to an EFI circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) The present invention provides a pressure detection device that measures differential pressure between upstream and downstream of a throttle valve for engine fuel injection control, etc.;
More specifically, the present invention relates to a pressure sensing device that performs zero pressure calibration upon startup in order to prevent zero pressure drift of such a pressure sensing device.

2. Description of the Related Art Electronic fuel injection devices (hereinafter referred to as EFI) that control fuel injection devices using electronic circuits are widely used.

First, the EFI stabbing method will be explained with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing the basic structure of the EFI control system, and FIG. 2 is a graph showing the relationship between differential pressure value and injection pulse width.

The EFI @ control method basically utilizes the fact that the intake air flow rate of the engine is roughly proportional to the pressure in the intake pipe, and by detecting this pressure, the intake air flow rate is known and the fuel injection amount is adjusted. By doing so, the optimum air-fuel ratio is obtained.

A differential pressure sensor 10 is used to detect (2) a differential pressure value e between the inlet and outlet of the throttle valve 11 in order to measure the pressure in the intake pipe of the engine.

Furthermore, since the relationship between the intake air flow rate and the intake pipe internal pressure is a multivalued function of the engine rotational speed, the zero rotational speed at which the rotational speed is corrected is obtained by the ignition signal from the ignition circuit 12.

In the control circuit 13, a fuel injection pulse width is calculated from the differential pressure value e and the rotational speed N, and a proper injection amount q of fuel is injected from the injector 14.

In the EFI control method, as shown in Figure 2, at a certain rotation speed N 1 + N 2, the relationship between the required injection pulse and the differential pressure value is a curve that rapidly increases as the differential pressure value approaches zero. Become. In other words, when the throttle valve is in the fully open position, this differential pressure is extremely small, making accurate measurement difficult due to the accuracy of the differential pressure sensor.

In particular, in engines with throttle valves for each cylinder, the rate of change of the injection pulse curve is large when the differential pressure value is near zero, and drift at the zero point of the differential pressure sensor can result in a large air-fuel ratio error. It's coming.

However, in the differential pressure sensors currently in use, although it is easy to take measures against drift due to temperature, it is difficult to take measures against the drift at the zero point because it deviates significantly due to aging, pack fire, etc.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pressure detection device that performs zero pressure calibration at startup in order to improve the detection accuracy near zero differential pressure of a differential pressure sensor that detects the differential pressure between upstream and downstream of a throttle valve. There is a particular thing.

In order to achieve the above object, the pressure detecting device according to the present invention includes a differential pressure detecting means for detecting a differential pressure between upstream and downstream of a throttle valve, and a pressure detecting device that detects a differential pressure between upstream and downstream of a throttle valve, and a pressure detecting device that detects a differential pressure when the ignition switch is on and the engine speed is zero. On the condition that A pressure output is connected, and a holding means holds the differential pressure (3) output until the first sample hold command signal is generated in response to the hold command signal, and a holding means holds the differential pressure (3) output until the first sample hold command signal is generated. It consists of an arithmetic device that outputs the difference between the output of the pressure detection means and the output of the pressure detection means.

According to the above configuration, the zero point is determined on the condition that the evening ray scene switch is on and the engine speed is zero, and the pressure is thereafter detected based on this, so there is no detection error near zero differential pressure. is reduced, and the objective of the present invention can be fully achieved.

Hereinafter, the present invention will be explained in more detail with reference to the drawings and the like.

FIG. 3 is a circuit diagram showing an embodiment of a circuit used in the pressure detection device according to the present invention.

The structure and operation of this embodiment circuit will be explained with reference to the waveform diagram shown in FIG.

When the ignition switch lG554 is closed, the first input terminal of the gate G becomes a high level (Fig. 4
+). FIG. 4 shows this point in time as to. An ignition pulse is input, and the FV converter FV maintains the level when the number of rotations is 0, and becomes low level when the occurrence of rotation is detected. Since the output of this FV converter FV maintains a high level at the time of to, the third output of gate G
The input terminal G1n3 of is at high level. Starter ST
The terminal is an inverter! It is connected to the second input terminal G1n2 of the gate G via n. This second input terminal G
1n2 is when the starter switch STsw is closed (
At time t1 in FIG. 4), the output Gout of the gate G becomes low level.

The sample and hold circuit S&H is always connected to the battery B, and is configured to hold the output of the differential pressure sensor 10 when the output of the gate G falls. Note that when the starter switch STsw is turned on, that is, G1n2
Even if you do not hold it at the falling edge of G1n1, G1n
2. If the conditions for G1n3 are met, it may be held at that point, that is, the ignition switch Igs-
If it is on and the rotation speed is zero, you can hold the sample.

The output of the sample and hold circuit S&H is connected to the inverting input terminal of the differential amplifier (6) AMP, and is connected to the inverting input terminal of the differential amplifier (6) AMP.
Hold voltage e6 is output at the time point.

The differential pressure sensor 1 is connected to the inverting input terminal of the differential amplifier 11AMP.
0 output is connected, and e from the differential amplifier SAMP is connected.
The output of ll-eO-62 is fed to the EFItll path.

The hold voltage e6 is updated every time the device is started. Since the sample and hold circuit S&H is always backed up by battery B, it holds the previously held voltage 6Q until the next sample and hold is performed.

Therefore, even if the starter switch 5Ts- and the evening scene switch IGaw are turned on at the same time and the susceptible hold is not performed, no problem will occur because the previous hold value will be used.

FIG. 5 is a circuit diagram showing still another embodiment of the circuit used in the pressure difference detection device according to the present invention.

This embodiment utilizes a micro combinator installed in a vehicle, and the operation procedure related to the present invention is described in the sixth section.
I! It is shown in I.

In FIG. 5, a microprocessor 51 is a device including a microprocessor and a memory, and also has control functions for other parts not related to the present invention.

The power supply 51 is the main power supply device of the microphone dicombinator,
Power is supplied from when the ignition switch IGsw is turned on. The power supply 52 is a memory backup power supply.

The output of the differential pressure sensor IO is input to the micro combinator 55 via the A/D converter 53.

A crank angle sensor 54 is a sensor for detecting the rotation of the engine, and is similarly connected to the micro combinator 55 via an interface 56.

When the evening scene switch IGsw is turned on, the device is reset, input and output are initialized (101), and the program is started.

The control program samples the differential pressure sensor input on the condition that the starter switch STaw is off (102) and that there is no rotation pulse (7) (103).

Provided that there is no rotation pulse in this sample (105), the above contents are stored in a memory banked up by a battery (106), and this stored value corresponds to e6 in the above-mentioned embodiment. be.

The procedures (107) and (10B) correspond to the operation of the differential amplifier i1AMP of the embodiment described above.

The differential pressure sensor input value (corresponding to el) is read (107
), the difference from the value stored in (106) is calculated (10 B), and this value is stored as a differential pressure value (1
09) and is used as data for various controls.

The value stored in step (109) is updated sequentially in the program cycle, and can be changed even if el or e6 changes.

(102), (103), (105) mentioned above
If the sample and hold conditions are not satisfied in step □, steps (107), (10B), and (109) are executed using the previously held eg equivalent amount (9) (8).

As explained in detail above, according to the present invention, the output of the differential pressure sensor is sampled and held every time the conditions that the evening light switch is on and the engine speed is zero are satisfied, and zero point calibration is performed. Therefore, the accuracy of pressure measurement near zero can be improved, and highly accurate control data can be provided.

Although the embodiments have been described in detail above, various modifications can be made within the scope of the present invention.For example, as shown in FIG.
As shown in FIG. 2, the differential pressure sensor 10 may be mounted at any position where pressure is generated by the flow of intake air.

In addition, as shown in FIG. 7(B), the differential pressure sensor 10 uses two absolute pressure sensors 10a and IQb, and a differential amplification 11
It may be electrically processed by 0c.

Note that the pressure detection device according to the present invention can be suitably applied not only to an EFI system but also to a carburetor control 1 ignition, an EGR (10) system, and the like.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing the basic configuration of the EFI control system, Figure 2
The figure shows the relationship between differential pressure value and injection pulse width.
F! ! J is a circuit diagram showing an embodiment of the circuit used in the pressure difference detection device according to the present invention, FIG. 4 is a waveform diagram for explaining the operation of the same embodiment circuit, and FIG. 5 is the pressure difference detection device according to the present invention. FIG. 6 is a flowchart for explaining the operating procedure of the circuit, and FIG. 7 is a diagram showing a modified example of the pressure detection device according to the present invention. be. 10... Differential pressure sensor 11... Throttle valve 12... Ignition circuit 13... EFI circuit 14...
- Injector 51, 52...Power supply 53...A/D converter 54...Crank angle sensor 55...Micro combiator 56...Interface IGsw...Ignition switch STsw...
Starter switch FV...FV converter S&H...sample hold circuit G...game) AMP...differential amplifier Patent applicant Suzuki Motor Co., Ltd. agent Patent attorney Hisashi Inoro (11) Figure 1 , 21.1 2'3 figure esw N eJ, In Tout IGPF■ (12) Figure 25 off figure (A) (B) Procedural amendment March 12, 1980 Commissioner of the Japan Patent Office Shima 1) Haruki Tono1, Indication of the case Patent Application No. 20369 of 1982 2, Name of the invention Pressure detection device 3, Person making the amendment Relationship to the case Patent applicant 4, Agent 6, Specification to be amended 7, Contents of the amendment Details of the amendment as shown in the attached sheet (Japanese Patent Application No. 57-20369) (1) The scope of the claims is amended as follows. ``2. Claims: Differential pressure detection means for detecting the differential pressure between upstream and downstream of the throttle valve, and a starter switch provided that the ignition stirrup switch is on and the engine speed is zero. generates a sample command signal before the
The difference W between the sample hold command signal generation means that generates a hold command before the starter switch is turned on or the engine rotates or by these numbers, and the differential pressure detection means.
The output is connected to the hold command signal 'j,
a sample and hold means for holding the differential pressure output until a primary sample and hold command signal is generated; and an arithmetic device for outputting a difference between the value held by the sample and hold means and the output of the differential pressure detection means. (2) In page 4, line 17 of the specification, ``by engine rotation'' is corrected to ``before engine rotation or by these signals.''that's all

Claims (1)

[Claims] A starter switch includes differential pressure detection means for detecting differential pressure between upstream and downstream of the throttle valve, and a starter switch provided that the ignition change switch is on and the engine speed is zero. Generates a sample command signal before being input,
Sample and hold command signal generation means that generates a hold command when the starter switch is turned on or the engine rotates is connected to the differential pressure output of the differential pressure detection means. A sample hold means holds the differential pressure output in response to the hold command signal until the ninth sample hold command signal is generated; and a value held by the sample hold means and the output of the differential pressure detection means. A pressure detection device consisting of an arithmetic device that outputs the difference between