JPS59202025A - Internal combustion engine intake flow rate detection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Technical Field> The present invention relates to a device for detecting the intake flow rate of an internal combustion engine.
Especially detection) related to those with improved forelimbs.

<Background technology> Electronic? In an internal combustion engine βJ equipped with a No. 11 control fuel injection device, generally based on the intake flow rate Q and the engine speed N,
The basic fuel injection amount Tp (-KQ/N), which is proportional to the amount of air taken into the cylinder per revolution, is set, and this is corrected with the cooling water temperature, etc. to obtain the final fuel injection amount Tiff1.
I am trying to set it.

In this case, a heat gland type viC amount detector as shown in FIG. 1 is conventionally known as the intake air flow rate detection device 1. This is platinum as a hot wire stretched inside a detection tube 3 attached to the intake pipe 2 on the second flow side of the throttle valve 1. l! By flowing frost at 4 and +5ii; and changing the pressure so as to keep the terminal voltage of Shirokane, which is about to change according to the intake flow rate, constant, the amount of intake air vfi', which is proportional to the output 1tL pressure, is It is designed to be detected.

However, in such a hot wire type flow f:1 detector, since the intake air flow rate flowing through the detection cylinder stretched with platinum wire is small, the change in output voltage with respect to the change in the total intake air flow rate is small, and the error rate is (Detection error value / 1 intake flow rate) In the low intake θfil drag region (low load region) where a large amount of (detection error value / 1 intake flow rate) occurs, it is not possible to detect the intake air transfer with crystal precision, which in turn reduces the control accuracy of the fuel injection amount etc. based on this detected value. The result was that

If the intake passage area is made smaller, the detection accuracy will be improved by increasing the proportion of intake air passing through the detection cylinder, or the passage resistance will increase in the high load region of the intake flow rate and the intake filling rate will decrease. This is not preferable because it causes a decrease in output.

<Object of the Invention> For this reason, the present invention includes a hot wire type flow rate detector similar to the conventional one as shown in FIG. , means for detecting the variable intake passage area, and means for detecting the intake flow rate from the hot wire passage air amount detected by the hot wire flow rate detector and the intake passage area detected by the intake passage area detection means. The configuration includes the following.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. In the third garden (B) showing an example, a detection tube 123 with a platinum wire 11 as a hot wire stretched as in the conventional case and a detector 1ti'r'l) connected to the platinum wire 11 are shown.
A hot wire flow rate detector is attached to the wall of the intake pipe 15 of the four-stroke valve 14 upstream 111. A device for changing the area of the intake passage around the outside of the detection tube 12 is provided.

That is, a cylindrical piston 17 is slidably inserted into a cylindrical case 16 fixed to the outer wall of the intake pipe 15, and the top of the piston 17 is inserted through a hole 18 opened in the top wall of the case 16 and the wall of the intake pipe 15. The intake pipe 15 is drawn out while maintaining airtightness, and a spring 20 is fitted between the plate 19 fixed to the inner wall of the case 16 and the inner surface of the top wall of the piston 17. An intake pressure passage 21 is provided to guide the intake negative pressure generated in the intake pipe 15 to the inner space of the piston 17 through a hole 19a opened in the plate 19, and the spring 20 is activated in response to an increase in the intake negative pressure. The piston 17 is configured to descend to a position where it balances with the drag force, thereby changing the intake passage area of the upper portion of the top wall of the piston 17 to which the detection tube 12 is attached.

Further, the lower end of the rod 22 made of a magnetic material whose upper end is fixed to the center portion of the top wall of the histone 17 is attached to the plate 19.
The rod 22 is slidably inserted through the center of the rod 22.
A differential transformer detector 23 is disposed around the outer periphery of the lower end.

That is, the differential transformer detector 23 detects the intake passage area of the portion where the detection tube 12 is attached by detecting the position of the rod 22 that is integrated with the piston 17.

The signal from the detection circuit 13 and the differential transformer detector 2
The signal from 3 is sent to the h/p converter 24 along with the cooling water temperature signal from the water temperature sensor as shown in the control block diagram of FIG.
The signal is input into the microcomputer 25 for fuel injection amount control after being converted into a digital signal. In addition to the above-mentioned signals, the input port 25A of the microcomputer 25 receives an engine speed signal from a crank angle sensor and an idle detection signal from an idle switch.

The microcomputer 25 has an input port 25A and an output port 25BS.
cpU25C, ROM25D and RAM M25E'''c
The fuel injection rate is controlled based on the various input signals. Hereinafter, control side] flow k8Q will be explained according to the flowchart shown in FIG.

Based on the output A from the detection circuit 13, the air flow QS that passes through the Suzuki platinum wire 11 is determined from the map stored in the ROM 25DKEL (Stoo), and the output B from the differential transformer detector 23 is determined. Based on this, the intake passage area S is obtained from the map also stored in RCBVi25D, and (81
10), Calculate the intake flow rate Q as Q=QSXS (3
120).

Below, as before, the basic injection amount 'rp is T p = KQ/N
(S130), the final 11f1 ejaculation T is calculated based on the cooling water temperature and the signal indicating whether it is idle or not.
i is corrected (8140), and a pulse signal with a pulse width corresponding to Ti is output from the output port to the power transistor 26 to drive the fuel injector 27 and control 1 for fuel injection (Sl 5 (+) .

In this way, in a low preload region where the intake flow is small, the intake negative pressure acting on jIIJ in the piston 17 is small, and the amount of descent of the piston 17 is small, so the area of the intake passage of the detection tube 12 mounting part can be reduced. 9, the proportion of the intake air flowing through the detection cylinder 12 increases. As a result, the change in the output voltage from the detection circuit 13 in response to the change in intake flow rate increases, so
The accuracy of intake flow rate detection is improved, and the accuracy of surgical injection amount control can be increased. On the other hand, in a high load region with a large intake flow rate, the amount of descent of the piston 17 increases due to the increase in intake negative pressure, which reduces the intake passage area of the detection tube 11 attachment part and reduces the intake passage resistance. Intake air filling efficiency can be achieved and high output performance can be ensured.

Furthermore, since the intake air detection error rate is originally small under high load, optical detection accuracy can be ensured.

In this embodiment, the intake passage is made variable by a piston that responds to intake negative pressure, but a shutter that is biased in the closing direction by springing a torsion coil is also installed at the detection tube attachment part of the intake pipe. The configuration may be such that the opening degree of the shutter increases as the intake flow rate increases, or the configuration may include a shutter that increases the opening degree in response to an increase in the throttle valve opening degree.

<Effects of the Invention> As explained above, according to the present invention, the intake passage area of the detection tube attachment part of the hot-wire flow rate detector is made variable according to the engine operating condition (-N), which improves output performance, etc. While ensuring this, the accuracy of intake flow rate detection can be improved, and the effect of improving the control accuracy of fuel injection, etc. can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of a conventional intake flow rate detection device equipped with a hot wire flow rate detector, Fig. 2 is a block diagram explaining the present invention in detail, and Fig. 3) is an embodiment of the present invention. A cross-sectional view showing the main parts of the same book (Bl is a cross-sectional view taken along the line A-A in the same figure (A), FIG. 4 is a block diagram showing the control circuit section of the same embodiment, and FIG. 5 is a diagram showing the same implementation) It is a flowchart diagram showing an example control flow. 11... Platinum wire 12... Detection fm] 13... Detection circuit 15... Intake pipe 16... Case
17...Piston 19a...hole 20...spring 21...intake air intake/outlet path 22...rod 23...differential transformer detector 24...A
/D Henkyuki 25...Microcomputer Fig. 3 (A) Fig. 5

Claims (1)

[Claims] In an intake air flow rate detection device for an internal combustion engine, a hot wire type flow rate detector consisting of a detection tube with a hot wire stretched thereon and a detection circuit connected to the hot edge is attached to the intake pipe. means for varying the area of the intake passage around the outside of the detection cylinder; means for detecting the variable intake passage area; Detectability of intake flow rate of an internal combustion engine characterized by providing a means for detecting the intake flow rate! 5
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