JPS5944502B2 - Internal combustion engine intake passage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the shape of an intake passage for an internal combustion engine from an air cleaner to a fuel supply device such as a carburetor.

FIG. 1 shows a fuel supply system using an electronically controlled fuel injection system, which was previously proposed by the present applicant in Utility Application No. 54-94367.

In the figure, 1 is the fuel supply device (main body), 2 is the throttle valve,
3 is a fuel injection valve, 4 is an injection valve holder incorporating a pressure regulator (fuel pressure regulating device), and 5 is an air cleaner housing.

The throttle valve 2 is interposed in the middle of an intake passage 6 passing through the main body 1, and the fuel injection valve 3 is provided further downstream.

The intake passage section 6 communicates with the engine intake manifold gathering section γ, and is configured to distribute the air-fuel mixture to each cylinder.

On the other hand, the inlet section 6A of the intake passage section 6 is provided with a disk-shaped lower disk 8 and an upper disk 9.

The upper disk 9 is provided via a spacer (not shown) so as to maintain a predetermined distance from the lower disk 8,
An annular intake air introduction path 11 is formed.

The air cleaner housing 5 is held by the outer periphery of the lower disk 8 and the upper surface of the upper disk 9, and is
An annular cleaner element 12 is housed so as to surround the.

In this device, an intake air amount sensor 13 is interposed in a part of the intake air introduction passage 11, so that the intake air amount can be detected as a single line for controlling the fuel injection amount.

The intake air amount sensor 13 includes a duct portion 14 through which a portion of intake air passes, a honeycomb-shaped rectifier 15, a vortex generator 16, a heat wire 17, etc., which are interposed in the duct portion 14.

The rectifier 15 is provided near the inlet and near the outlet of the duct portion 14, and the vortex generator 16 and the hot wire 17 are located between these two rectifiers 15.

The hot wire 1T is located on the downstream side of the vortex generator 16 and is connected to the duct part 1.
The intake air amount signal is output by capturing the change in temperature (resistance value) when a vortex (Karman vortex) generated when a part of the intake air flows into the intake air 4 crosses the hot wire 1T.

In other words, the frequency of occurrence of vortices changes depending on the intake air flow velocity, and this change is converted into an electrical signal to detect the amount of intake air.

In addition to such an intake air amount sensor 13, a hot wire flow meter may be used that detects the flow rate by only detecting temperature changes in the hot wire depending on the intake air flow velocity.

The intake air amount signal is adjusted via the waveform shaping circuit 18 and input to the control circuit 19 together with other signals (for example, a crank angle signal) that typically represent the engine operating state.

The control circuit 19 controls the fuel injection valve 3 based on these signals.
The duty ratio of the pulse signal is determined, and the amount of fuel is always controlled to be appropriate for the operating conditions.

By the way, in such an electronically controlled fuel injection system, as is clear from the above, the amount of intake air passing through the intake air amount sensor 13 (duct portion 14) represents the total amount of intake air in the engine. In order to accurately control the fuel ratio, it is necessary to always keep the ratio of the amount of intake air introduced into the duct portion 14 to the total amount of intake air constant.

However, in the above device, turbulence occurs downstream of the intake air amount sensor 13 due to a sudden change in the direction of the intake air flow from the intake air introduction path 11 to the intake passage section 6. There is a problem that the ratio fluctuates unstablely.

In particular, since the Karman vortex is easily influenced by intake air turbulence on the downstream side, the detection accuracy of the intake air amount tends to decrease.

The present invention was made in view of the above-mentioned problems, and in order to suppress disturbances in the intake air flow and improve detection accuracy of the intake air amount sensor, the intake passage entrance is formed in a venturi shape that smoothly connects with the intake air introduction passage. The present invention provides an intake passage device with the following features.

The present invention will be explained below based on the embodiment shown in FIG.

In the present invention, as shown in the figure, the venturi portion 20 is arranged so as to smoothly connect to the intake passage 11 at the intake passage entrance portion 6A.
The length of the passage until the intake air changes direction from the introduction passage 11 to the passage part 6, that is, the length of the straight portion downstream of the sensor 13, is increased.

Although the figure shows an example in which the venturi portion 20 and the lower disk 8 are integrally formed, it goes without saying that they may be formed in the fuel supply device 1 (intake passage portion 6).

The throat diameter of the venturi section 20 is suitably about 80 to 90% of the inner diameter (bore) of the intake passage section 6.

Since the rest is the same as in FIG. 1, the same parts are denoted by the same reference numerals.

According to the above configuration, the intake air amount sensor 13 of the intake air introduction path 11
The straight line portion downstream of
Since the venturi portion 20 and the venturi portion 20 are formed so as to be connected smoothly, the change in direction and disturbance of the intake air flow toward the intake passage portion 6 have almost no effect on the intake air amount sensor 13.

Further, in the venturi section 20, the intake pulsation (pressure fluctuation) which becomes a problem when the throttle valve opening degree is large is alleviated to some extent, so the detection accuracy of the intake air amount sensor 13 is further improved.

Furthermore, since the venturi section 20 also exhibits a rectifying effect, it also contributes to improving the air-fuel mixture distribution characteristics, especially in a multi-cylinder engine.

As described above, according to the present invention, it is possible to suppress turbulence and deflection of the intake air flow, thereby improving the measurement accuracy of the intake air amount.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional example, and FIG. 2 is a sectional view of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Fuel supply device, 6...Intake passage section, 6A...Intake passage entrance section, 11......
・Intake air introduction path, 13...Intake amount sensor, 20・
...Venturi section.

Claims (1)

[Claims] 1. An intake passage device that surrounds the intake passage entrance of a fuel supply system for an internal combustion engine with an annular intake introduction passage, and interposes an intake air amount sensor so that a portion of the intake air passes through the annular intake passage at a constant rate. The intake passage entrance part is formed in a venturi shape that smoothly connects with the annular intake introduction passage, and the passage length downstream of the intake air amount sensor until the intake air flow is diverted from the intake intake passage to the intake entrance part is lengthened. An intake passage device for an internal combustion engine, characterized by: