JPH0223697B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake air amount supply device for an internal combustion engine.

[Conventional technology]

As a conventional intake air amount supply device for an internal combustion engine, the one disclosed in Japanese Utility Model Application Laid-Open No. 53-38522 has been known.

[Problem to be solved by the invention]

However, in this device, since the throttle valve and the intake air amount detection section are connected through a long passage, there is a problem in that the response to changes in air amount is slow. That is, when the throttle valve is opened and the air increases, it takes time for the intake air amount detection section to detect this increase, which is undesirable for determining the fuel injection amount.

Furthermore, since the two are connected by a long passage, a large amount of space is required in the engine room, and there is also the problem that other equipment cannot be placed there.

Furthermore, when inspecting the product, the throttle valve section and the intake air amount detection section must be inspected separately, which results in a time-consuming inspection and a problem in that a comprehensive inspection cannot be performed.

Furthermore, in the intake pipe from the air cleaner to the intake valve, air column vibration occurs due to the opening and closing of the intake valve, and this air column vibration becomes an antinode (maximum amplitude of air column vibration) at the air cleaner section, and an antinode (maximum amplitude of air column vibration) at the end of the intake pipe. node (minimum amplitude of air column vibration). Therefore, if you place the air flow meter near the "antinodes" of the air column vibration, the air flow meter will also detect the air flow due to the air column vibration, resulting in an air column above the air flow being inhaled by the engine. The air flow meter outputs a signal in which the vibrating airflow caused by vibration is superimposed. That is, the signal from the air flow meter becomes a signal containing a lot of noise, which is inconvenient.

In addition, the air-fuel supply system of an internal combustion engine has a function to draw blow-by gas into the engine, but when this function is added, the blow-by gas adversely affects the characteristics of the heating element that makes up the thermal air flow meter. I have to try not to give it away. Conventionally, blow-by gas was led into the air cleaner from the engine's crank chamber, but with this configuration, there was a risk that when the blow-by gas came into contact with the heating element, tar would adhere to the surface of the heating element, causing deterioration of its characteristics. There is.

[Means to solve the problem]

In order to solve the above problems, the present invention employs the following configuration.

(a) an intake air amount measuring assembly having an upper intake air passage through which intake air taken into the internal combustion engine flows; and a thermal air flow meter disposed in the upper intake air passage for measuring the amount of intake air; (b) ) A lower intake air passage configured separately from the intake air amount measuring assembly and into which intake air flowing out from the upper intake air passage flows, and a throttle valve arranged in the lower intake air passage for adjusting the amount of intake air. (c) the thermal air flow meter of the intake air amount measurement assembly and the intake air amount adjustment assembly; (d) A blow-by gas inflow hole opened between the adjustment assembly and the throttle valve; (d) A blow-by gas inflow hole configured separately from the intake air amount adjustment assembly and connected to the combustion chamber of the internal combustion engine so as to inflow from the lower intake air passage. An intake air supply device for an internal combustion engine, comprising an intake pipe which sends flowing intake air to the combustion chamber of the internal combustion engine and is integrated with the intake air amount adjusting assembly in close contact with each other. It is in.

[Effect]

According to the above configuration, when the throttle valve is opened, the thermal air flow meter located immediately above the throttle valve detects a change in the amount of air.

Moreover, since it is integrated, no extra passage space is required.

Furthermore, both can be comprehensively inspected at the same time.

Furthermore, the thermal air flow meter is installed from the air cleaner where the "antinode" where the amplitude of the air column vibration is maximum is located to the intake valve where the "node" where the amplitude is the minimum is located, so that the air column vibration There will be less noise.

Furthermore, since the blow-by gas is supplied between the thermal air flow meter and the throttle valve, there is less risk of tar adhering to the surface of the heating element of the thermal flow meter and causing deterioration of characteristics.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

In Fig. 1, intake air is supplied to air cleaner 8,
It is supplied to an internal combustion engine (hereinafter referred to as engine) 1 through a throttle chamber 4 and an intake pipe 2, and is ignited and combusted by a spark plug 9. This combustion gas is discharged from the engine 1 to the atmosphere through the exhaust pipe 3.

Fuel is pressurized from a fuel tank 13 by a fuel pump 14, passes through a filter 15 and a pressure regulator 16, and then enters a fuel injection valve (hereinafter referred to as an injector) 5.
reach. The fuel pressure is set to the set pressure of the pressure regulator 16 in the range of 0.4 to 5 kg/cm ² , and excess fuel is returned to the fuel tank 13 through the pipe 18 .

The injector 5 is driven by an electric signal from a control circuit 11 (consisting of a microcomputer operated by electric power from a battery 12, an input/output circuit, a signal processing circuit, etc.), and is supplied to the engine 1 according to the magnitude of the opening/closing time. Control the amount of fuel.

The fuel ejected from the injector 5 is atomized in the air passage of the throttle chamber 4, mixed with intake air, passes through the intake pipe 2, and is supplied to the engine 1. It is then ignited by a spark plug. Reference numeral 17 is an oxygen sensor provided in the exhaust pipe, and reference numeral 19 is a water temperature sensor for cooling water of the engine. This information is input to the control circuit 11 to correct the air-fuel ratio.

As shown in FIG. 2, in order to prevent the air flow velocity near the outlet of the injector 5 from decreasing when the primary and secondary throttle valves 20 and 21 are fully opened, the Next throttle valve 21
A diaphragm device 7 is provided to keep the diaphragm closed. When the air flow rate increases, the negative pressure to the diaphragm device 7 increases and the secondary throttle valve 21 is opened to suppress an increase in suction resistance.

Throttle chamber 4 primary and secondary throttle valves 2
An electric heating element constituting the thermal air flow meter 6 is disposed in the air passage upstream of the air flow meter 6, and an electric signal corresponding to the air flow rate determined from the relationship between the air flow rate and the heat transfer amount of the heating element is sent to the control circuit. 11. The heating element is disposed in a detour passage (hereinafter referred to as bypass passage) 22 to protect the heating element from high-temperature, high-pressure gas generated when the engine 1 backfires, and from being contaminated by dust in the intake air. can be prevented. The outlet of the bypass passage 22 opens near the narrowest part of the bench lily 23, and the entrance of the bypass passage 22 opens on the upstream side of the bench lily 23.

The specific construction of the throttle chamber is explained in detail in FIG.

In FIG. 2, an intake air amount adjustment assembly 200
A primary throttle valve 20 that is mechanically connected to an accelerator pedal (not shown) and a secondary throttle valve 21 that is driven by a diaphragm device 7 via a rod 30 are arranged in parallel in the throttle chamber 4 that constitutes the throttle chamber 4. The lower intake air passages 31, 32 in which the respective throttle valves 20, 21 are disposed are connected to the upper intake air passage 34 formed in the intake air amount measuring assembly 100 upstream of the respective throttle valves 20, 21. to join. Note that the intake air passages 30 and 31 are separated by a partition 4.
It is divided into 8 sections. A bench lily portion 23 is formed in this upper intake air passage 34.

Further, a bypass passage 22 is provided so as to branch from the upper intake air passage 34 above the bench lily part 23 and join the upper intake air passage 34 again at the bench lily part 23.
A heating element of the thermal air flow meter 6 is disposed.

The bypass passage 22 also includes a metering orifice 37 that detects the temperature of the air and generates a signal from the heating element of the thermal air flow meter 6 in order to keep the division ratio of air flowing between the bypass passage and the upper intake air passage 34 constant. A thermistor 38 is provided for correcting.

The electrical signal of the heating element of the thermal air flow meter 6 is connected to the control circuit 11, although the drawing terminal is not shown in the drawing.
The electrical signal of thermistor 38 is also applied to terminal 3.
9 leads to the control circuit. Note that reference number 74 is a spacer for forming the bypass passage 22.

The negative pressure of the bench lily portion 23 is guided to the diaphragm chamber 7a of the diaphragm device 7 through a negative pressure passage 41, and when the negative pressure of the bench lily reaches a predetermined value, the diaphragm 7b to which the rod 30 is connected compresses the spring 7c. While moving, the secondary throttle valve 21 is opened.

A fast idle passage 42 for flowing air during fast idle is provided so as to communicate above and downstream of the secondary throttle valve 21 . A valve 43 is provided to supply a large amount of air to the engine through the fast idle passage 42, and to accelerate warm-up by supplying a larger amount of fuel from the injector 5 than in normal idling operation.

The nozzle 5a of the injector 5 is a primary throttle valve 20.
An assist air passage 46 having an inlet upstream of the primary throttle valve 20 communicates with the nozzle 5a in the middle of the nozzle 5a. When the primary throttle valve 20 is at the idle opening degree, a large pressure difference occurs before and after the primary throttle valve 20, so the assist air passage 4
Air flows through the injector 6 to promote atomization of the fuel intermittently injected from the injector 5,
This prevents the intermittently injected fuel from clumping up and being sucked into the engine, and smooths it out. An orifice 47 is inserted into the assist air passage 46 to adjust the amount of air flowing through this passage.

Further, an eave-like protective cover 51 is provided above the bypass passage 22 to prevent solid matter, fibrous debris, etc. that enter from the air cleaner 8 from adhering to the heating element of the thermal air flow meter 6. This prevents the air flow rate detection accuracy from deteriorating.

In this embodiment, in the operating range where the amount of intake air is small, the negative pressure in the bench lily portion 23 is small, so the diaphragm device 7 is not activated.
Since the amount of intake air to the engine mainly passes through the lower intake air passage 31 in which the primary throttle valve 20 is provided, the air flow velocity near the tip of the nozzle 5a of the injector 5 is high, and assist air flows through the assist air passage 46. Therefore, fuel atomization and smoothing are improved, and when applied to a multi-cylinder engine, the distribution characteristics of the air-fuel mixture to each engine are improved.

When the amount of intake air to the engine increases, the negative pressure in the bench lily section 23 increases, which activates the diaphragm device 7 and opens the secondary throttle valve 21, so that the intake resistance does not increase and the engine generates sufficient output.

During engine operation, the air division ratio between the bypass passage 22 and the upper intake air passage 34 is constant;
By controlling the opening/closing time of the injector 5 in accordance with the electric signal of the heating element of the thermal air flow meter 6, the air-fuel ratio of the mixture generated can be determined depending on other conditions (for example, air temperature,
If the density) is the same, it will be constant. However, in engines such as automobile engines where the ambient temperature changes significantly, the air-fuel ratio cannot be controlled to a desired value unless correction is made based on the air temperature, so a thermistor 38 is installed in the bypass passage 22. is arranged to correct the signal of the heating element of the thermal air flow meter 6 based on the signal of the thermistor 38.

The thermistor 38 for temperature correction is installed on the upstream side of the heating element of the thermal air flow meter 6 or in the air cleaner 8.
Although it may be provided in the bypass passage 22 as in the embodiment shown in FIG. 2, it can be protected from high-temperature gas during backup fire.

That is, a bypass passage 2 is provided in which the heating element of the thermal air flow meter 6 is separated from the upper intake air passage 34.
2 is provided to protect the heating element of the thermal air flowmeter 6 from the engine's backup fire. If the bypass passage 22 is configured as shown in FIG. 2, the amount of high-temperature, high-pressure gas that flows upward from below during backup will intrude into the bypass passage 22 side will be extremely small. This can be suppressed to such an extent that the characteristics of 38 are not deteriorated. In particular, the effect is further improved by forming the outlet of the bypass passage 22 into an annular groove along the inner circumferential wall surface of the upper intake air passage 34.

Since the nozzle 5a of the injector 5 slightly protrudes from the wall surface of the lower intake air passage 31 and also protrudes obliquely downward, the fuel injected from the injector 5 easily rides on the airflow. Therefore,
Compared to the case where the injector is arranged horizontally, the amount of fuel adhering to the opposing wall is smaller, and the problem of unstable idling due to adhesion to the wall has been significantly improved.

In addition, since the nozzle 5a protrudes from the wall surface, even if the fuel adhering to the inner wall of the nozzle 5a becomes droplets, it mixes with air at a position where the air flow rate is high, so there is a probability that the fuel will be supplied to the engine as droplets. becomes smaller and contributes to stabilizing idling operation.

As described above, the present invention is characterized in that the assembly 100 having the thermal flowmeter 6 and the assembly 200 having the throttle valves 20 and 21 are integrated in close contact with each other.

Note that a flange is formed on the joint surface of the intake air amount measuring assembly 100 and the intake air amount adjusting assembly 200, and they are fixed together by known bolting or the like. In addition, the intake pipe 2 and the intake air amount adjustment assembly 2
Similarly, the joint surface of 00 is also provided with a flange and is fixed integrally by known bolting or the like. Here, the intake pipe 2 is manufactured using a mold and is fastened and fixed to the internal combustion engine 1 with bolts or the like, similar to conventional devices.

The embodiment shown in FIG. 3 improves the characteristics at full open low speed by combining a primary throttle valve and an air valve, and the negative pressure control valve 60 is provided in the lower intake air passage 58 downstream of the throttle valve 20. This negative pressure control valve 60 is connected to a diaphragm 64 of a negative pressure device 63 via a lever 61 and a rod 62.
Note that this configuration is shown in FIG.

Negative pressure chambers 6 are provided on both sides of the diaphragm 64.
5 and 66 are formed, and pressure downstream and upstream of the negative pressure control valve 60 is introduced into each negative pressure chamber through negative pressure passages 67 and 68. Further, the diaphragm 64 is constantly applied with a leftward pushing force by a spring 69, and the negative pressure control valve 60 remains in the closed state shown in the figure until the pressure difference between the upper and downstream sides of the negative pressure control valve 60 reaches a predetermined value. ing. The negative pressure control valve 60 has a variable throttle 70 in the lower intake air passage 58 that maintains a predetermined pressure difference between the upper and downstream sides of the negative pressure control valve 60 even when the diaphragm 64 has changed to the maximum leftward. This means that you are giving

In an operating region where the amount of intake air of the engine is large, the pressure difference between the upper and downstream sides of the negative pressure control valve 60 is large, so the diaphragm 6
4 is displaced to the right to displace the negative pressure control valve 60 in the opening direction via the rod 62. On the other hand, in a region where the amount of intake air is small, the pressure difference between the upper and lower sides of the negative pressure control valve 60 is small, so the negative pressure control valve 60 is displaced in the closing direction. Therefore, the flow rate of the intake air amount of the engine at least in the portion of the variable throttle 70 becomes high, so that the atomization of the fuel and the distribution characteristics of the air-fuel mixture to each cylinder are improved.

In the embodiment shown in FIG. 4, the outlet of the bypass passage 22 in which the heating element of the thermal air flow meter 6 is provided is formed by a number of small holes 73 provided at regular intervals on the inner peripheral surface of the upper intake air passage 34. Bypass passage 2
This makes it easier to hold the spacer 74 for forming the second outlet.

That is, in the embodiment shown in FIGS. 2 and 3, the outlet of the bypass passage 22 is formed between the upper end of the spacer 74 and the inner circumferential wall surface of the upper intake air passage 34; Care must be taken to ensure that the exit area of the bypass passage 22 does not vary between products when press-fitted. However, in the embodiment shown in FIG.
4 is press-fitted until its upper end reaches the stepped portion of the inner circumferential wall of the upper intake air passage 34, the outlet area becomes the small hole 7.
Since it is determined by the total area of 3, it is possible to provide a device with little variation between products. The small hole 73 may have a slit shape instead of a circular hole, or may have a notch shape extending downward from the upper end of the spacer as the case may be. In this embodiment, the effect of protecting the heating element of the thermal air flow meter 6 against the engine backfire is substantially the same as in the previously described embodiment.

In the embodiment shown in FIG. 4, the adjustment passage 7 is arranged so as to bypass the orifice 37 of the bypass passage 22.
5 is provided, and an adjustment jet 7 is provided in this adjustment passage 75.
There are 6. By changing the adjustment jet 76, the aim is to obtain the same effect as substantially adjusting the flow passage cross-sectional area of the orifice 37, and adjusting the orifice 37 in this way is difficult in mass production. It's advantageous. In FIG. 4, the adjustment jet 76 is a fixed jet, but if it is made into a variable jet that can be adjusted from the outside, the adjustment work during mass production will be easier.

In the embodiments shown in FIGS. 5 and 6, the heating element of the thermal air flow meter 6 for detecting the air flow rate is arranged in a tube body 82 arranged in the center of the bench lily part 23 of the upper intake air passage 34. , Moreover, the thermal air flow meter 6
In order to protect the heating element, a deflecting member 86 having a triangular cross section is arranged below the tube body 82.

If the heating element of the thermal air flow meter 6 is placed in the center of the upper intake air passage 34, there is an advantage that errors caused by fluctuations in the flow division ratio are reduced compared to a case where the heating element is placed in the bypass passage 22. In such an arrangement, when engine backfire occurs, the heating element of the thermal air flow meter 6 is exposed to high-temperature, high-pressure gas, which may shorten the life of the heating element or change its characteristics, reducing measurement accuracy. I had a problem with it getting worse. In this embodiment, a deflecting member 86 having a triangular cross section approximately equal to the inner diameter of the tube is provided horizontally below the tube 82 with the base of the triangular cross section facing downward. This deflecting member 86 is in the form of an isosceles triangle whose other two sides are sufficiently longer than the base so that the air passing through the tube body 82 flows downward with less disturbance of the streamlines during engine operation. When a backup fire occurs, the function is to reduce the amount of high-temperature, high-pressure gas that enters the tube body 82, as shown by the arrow in FIG.

Returning to FIG. 1, the bypass passage 22 is provided with an orifice 136. In addition, a safety valve 13 is used to protect the pressure sensor 135 and the heating element of the thermal air flow meter 6 from high-temperature, high-pressure gas during backfire.
1 is provided.

A catalytic converter 138 and a muffler 139 are provided in the middle of the exhaust pipe 3.

A portion of the surrounding area of the intake pipe 2 is heated by cooling water or exhaust gas by the exhaust heating plate 132 to promote vaporization of the fuel.

A control valve 133 driven by the negative pressure adjusted by the negative pressure regulator 160 is provided in the middle of an air passage 137 having an inlet and an outlet upstream and downstream of the throttle valve 20, and the control valve 133 is installed in the middle of the air passage 137, which has an inlet and an outlet upstream and downstream of the throttle valve 20. Control the amount of air supplied to 1.

Further, an exhaust gas recirculation passage 134 is provided, and exhaust gas is returned to the intake pipe 2 through the exhaust gas recirculation passage 134 via an exhaust gas recirculation control valve 140.

The injector 5 has vapor bubbles in the fuel passage 142.
Installed diagonally to prevent air bubbles from stagnation,
The above-mentioned bubbles are arranged to escape towards the fuel tank 13 through the return fuel line 18. Specifically, the fuel passage inside the injector 5 is horizontal
It can have an inclination of about 30°.

The heating element of the thermal air flow meter 6 can be attached to the throttle chamber 4 via vibration damping means 143 such as rubber.

In the above, the system shown in Fig. 1 has an exhaust gas recirculation function and a function for sucking blow-by gas into the engine, but when these functions are added, the exhaust gas and blow-by gas are generated by the heat generated by the thermal air flow meter 6. It must be ensured that it does not adversely affect the physical properties of the body.

Conventionally, blow-by gas was led from the engine's crank chamber into the air cleaner 8, but in this configuration, when the blow-by gas comes into contact with the heating element of the thermal air flow meter 6, tar content is generated on the surface of the heating element 6. There is a risk of adhesion and deterioration of properties.

In this embodiment, the outlet sides of the blow-by gas passage 141 and the exhaust gas recirculation passage 134 are made into one and communicated with the inlet 170 of the air passage 137 for fast idle, and this inlet 170 is located slightly upstream of the throttle valve 20. Since it is open and is located downstream and away from the bypass passage 22 where the heating element of the thermal air flow meter 6 is installed, blow-by gas or exhaust gas does not reach the heating element of the thermal air flow meter 6. It is possible to prevent adverse effects.

Further, in this embodiment, since three passages communicate with the inlet 170, each passage needs to be connected to the intake passage at one place, which has the advantage of simplifying the configuration. However, it is often advantageous to provide the exhaust gas recirculation passage 134 and the fast idle air passage 137 separately from the viewpoint of the distribution characteristics of the air-fuel mixture.

In such a case, as in the embodiment shown in FIG.
Set 0. That is, the opening 180 opens between the thermal flowmeter 6 and the throttle valve 20.

In this case as well, blow-by gas or exhaust gas can be prevented from adversely affecting the heating element of the thermal air flow meter 6.

〔Effect of the invention〕

As described above, according to the present invention, since the intake air amount measuring assembly and the intake air amount adjusting assembly are integrated in close contact with each other, it is possible to quickly respond to changes in the intake air amount. The measurement section and adjustment section can be inspected at the same time without requiring extra engine room space, improving overall inspection time and inspection accuracy.

In addition, by integrating the air flow meter, the air flow meter is installed at a location away from the "antinode" position where the amplitude of air column vibration is maximum, which has the unique effect of reducing signal noise caused by air column vibration. .

Furthermore, since the blow-by gas is supplied between the thermal air flow meter and the throttle valve, there is less risk of tar adhering to the surface of the heating element of the thermal flow meter and causing deterioration of characteristics.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a control device for an internal combustion engine to which the present invention is applied, and FIGS. 2 to 6 are sectional views showing embodiments of the present invention. 1... Internal combustion engine, 4... Throttle chamber,
5... Injector, 6... Thermal air flow meter, 7
...Diaphragm device, 9...Spark plug, 11
...Control circuit, 14...Fuel pump, 20...Primary throttle valve, 21...Secondary throttle valve.

Claims (1)

[Scope of Claims] 1 (a) An upper intake air passage 34 through which intake air taken into the internal combustion engine 1 flows, and a thermal air flow meter 6 disposed within the upper intake air passage 34 to measure the amount of intake air. (b) lower intake air passages 31 and 3, which are configured separately from the intake air quantity measurement assembly 100 and into which the intake air flowing out from the upper intake air passage 34 flows;
2 and a throttle valve 2 arranged in the lower intake air passages 31 and 32 to adjust the amount of intake air.
(c) the thermal air flow rate of the intake air amount measuring assembly 100; 6 in total and the intake air amount adjustment assembly 20
(d) A blow-by gas inflow hole 180 opened between the throttle valves 20 and 21 of 0; The intake air flowing out from the air passages 31 and 32 is sent to the combustion chamber of the internal combustion engine 1, and the intake pipe 2 is integrated with the intake air amount adjustment assembly 200 in close contact with each other. Intake air supply system for internal combustion engines. 2. In the intake air supply device for an internal combustion engine according to claim 1, the thermal flow meter 6 of the intake air amount measuring assembly 100 is configured to supply a portion of the intake air provided in the upper intake air passage 34. An intake air supply device for an internal combustion engine, characterized in that the intake air supply device is disposed in a bypass passage 22 through which air flows.