JPS60147558A - Altitude compensation device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To permit to hold the mixture of carburettor in a high land in the optimum air-fuel ratio in any operating zone by a method wherein an altitude compensating air path is provided with a bypass path and the bypass path is provided with a vacuum control valve, opening and closing in accordance with the vacuum in the bypass path. CONSTITUTION:When atmospheric pressure is reduced in the high land, the bellows 3 of the altitude compensating valve 11 is expanded to close an releasing port 14. Accordingly, a diaphragm chamber 17 is kept in a high vacuum, as a result, a diaphragm 15 and a valve 18 are lifted up against a spring 16 and atmosphere from a filter 12 is introduced into the altitude compensating air paths 8, 10. According to the introduction, air is introduced into the fuel of fuel paths 5, 6 and the air-fuel ratio is thinned. In this case, a high vacuum is introduced into the diaphragm chamber 27 when the opening degree of a throttle valve 3 is low, for example, and the valve 29 is lowered against the spring 26 to close an atmosphere supplying path 22b. According to this method, the excessively thin air-fuel ratio in case the amount of suction air is small, for example, may be prevented and the optimum air-fuel ratio may be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an altitude compensation device for altitude compensating the concentration of a carburetor mixture of an internal combustion engine.

In the conventional technology internal combustion + ffl leap, the air pressure of the air-fuel mixture decreases as the altitude increases, and the air density decreases.
It gets darker. As a device for compensating for this, an altitude compensating device is conventionally known that introduces atmospheric air into the fuel passage of the carburetor to reduce the amount of fuel discharged as the altitude increases.

However, in this case, in a region where the slow fuel of the carburetor has a large effect on the air-fuel ratio of the mixture, even if air is introduced with the same orifice diameter in the atmosphere introduction passage, at idle The effect of reducing the amount of fuel output tends to be greater in the region where the amount of intake air is small, such as . Therefore, if the diameter of the air introduction orifice to the slow system is set so that an appropriate air-fuel ratio is achieved in a region where the amount of air is relatively large, the amount of air introduced will be excessive and the air-fuel ratio will become too lean in a region where the amount of air is small. ,
This may lead to deterioration in drivability such as unstable idling. Conversely, if you set the air-fuel ratio to be appropriate in a region where the amount of air is small, in regions where the amount of air is relatively large, the amount of air introduced will be insufficient and the air-fuel ratio will become overly rich, causing carbon monoxide and hydrocarbons in the exhaust gas to There has been a problem in that as the amount of emissions increases, the drivability may also deteriorate.

Purpose of the Invention In order to solve the above-mentioned problems, the present invention maintains the carburetor mixture at an appropriate air-fuel ratio in any operating range at high altitudes, ensures good drivability, and eliminates defective components in the exhaust gas. The aim is to reduce

Structure of the Invention In order to achieve this object, in the altitude compensating device for an internal combustion engine of the present invention, when the atmospheric pressure becomes small, the altitude compensating valve that supplies atmospheric air to the fuel passage of the carburetor flows into the slow system fuel passage of the carburetor. A bypass passage is provided in the conventional altitude compensation air passage, which is connected to a negative pressure outlet provided at the throttle valve position of the intake passage by a negative pressure passage. A negative pressure control valve is provided to open and close the valve.

Effect of the Invention In such an altitude compensation HE, the throttle diameter of the altitude compensation air passage leading to the slow system fuel passage is set so that an appropriate air-fuel ratio is achieved when the intake air amount of the engine is small. Is the orifice diameter suitable for when the intake air amount of the engine is large when air is sent from both the altitude compensation air passage and the bypass passage? The air-fuel ratio is set to ET. Whether or not the air from the bypass passage is added to the air from the altitude compensation air passage is controlled by opening and closing the bypass passage using a negative pressure control valve. The negative pressure control valve is controlled by the negative pressure at the throttle valve position, and when the throttle valve is opened at a low opening and high negative pressure, the bypass passage is closed, and the opening of the throttle valve is increased to reduce the negative pressure. Alternatively, the bypass passage is controlled to open when the pressure becomes close to atmospheric pressure. As a result, the amount of atmospheric air introduced into the slow system fuel passage is controlled to be large or small depending on the opening of the throttle valve, that is, the operating state of the engine. In areas where the amount of air is large, the amount of air is increased, and the air-fuel mixture is controlled to an appropriate air-fuel ratio.

Effects of the Invention Therefore, according to the present invention, when highly compensating the opening degree of the carburetor air-fuel mixture, it is possible to maintain an appropriate air-fuel ratio according to the operating state of the engine in any operating range where the amount of intake air differs. This has the effect of ensuring good operating conditions in all regions even at high altitudes and reducing the amount of harmful components in the exhaust gas.

Embodiments Below, preferred embodiments of the altitude compensating device for an internal combustion engine of the present invention will be described with reference to the drawings.

The figure shows an altitude compensator for an internal combustion engine according to an embodiment of the present invention, in which numeral 1 indicates a carburetor and numeral 2 indicates an intake passage. A throttle valve 3 is provided in the intake passage 2. The vaporizer 1 is equipped with a float chamber 4,
A main fuel passage 5 and a slow system fuel passage 6 for guiding fuel from the float chamber 4 to the intake passage 2 are formed.

The main fuel passage 5 communicates with the altitude compensation valve 11 via an altitude compensation air passage 8 having a throttle 7, and the slow system fuel passage 6 communicates with an altitude compensation air passage 1o having a throttle 9.

The altitude compensation valve 11 includes an atmospheric filter 12 that introduces atmospheric air through a line, a bellows 13 that expands and contracts according to atmospheric pressure, an opening 14 that opens and closes when the bellows 13 operates, and an opening 1.
4 is formed, a diaphragm 15, a spring 16
It consists of a diaphragm chamber 17 equipped with a diaphragm chamber 17, and a valve 18 that opens and closes communication of the atmosphere to the altitude compensation air passage 8.10. The diaphragm chamber 17 is communicated with the intake passage 2 downstream of the throttle valve 3 via a passage 19. The passage 19 is provided with a throttle 20 and a check valve 21.

A bypass passage 22 is provided in the altitude compensation air passage 10, and a negative pressure control valve 2 is installed in the middle of the bypass passage 22.
3 is provided. The passage 22a from the altitude compensation air passage 10 to the negative pressure control valve 23 is configured as an atmosphere introduction passage that guides the atmosphere in the altitude compensation air passage 10 from the upstream side of the throttle 9 to the negative pressure control valve 23. The passage 22b from the control valve 23 to the altitude compensation air passage 10 is connected to the negative pressure control valve 2.
3 to the downstream side of the throttle 9 in the altitude compensation air passage 10. A throttle 24 is provided in the atmosphere supply passage 22b.

The negative pressure control valve 23 includes a diaphragm 25 and a spring 26.
The valve 29 is connected to the diaphragm 25 and slidably fitted into the bush 28 to open and close the atmospheric supply passage 22b. The diaphragm chamber 27 is connected to the intake passage 2 through a negative pressure passage 30 and a negative pressure outlet 31 opened directly downstream of the throttle valve 3 at the position of the throttle pulse 13 in the intake passage 2.
is connected to.

The operation of the altitude compensation device configured as described above will be described below.

First, in a flat state, the atmosphere has normal atmospheric pressure, so the height compensation valve 11 has a hollow 13 as shown in the figure. Shrink as if
Mata state 4. The negative pressure of the intake passage 2 is guided to the diaphragm chamber 17 via the passage 19, but since there is a restriction 20, and the opening D14 is in the open state.
Since the diaphragm chamber 17 is communicated with the atmosphere by opening, the pressure in the diaphragm chamber 17 is approximately atmospheric. Therefore, the spring 16
The force pushes the diaphragm 15, and the valve 18 closes the inlet of the altitude compensation air passage 8.10, cutting off the supply of atmospheric air to the altitude compensation air passage 8.10. As a result, regardless of the operation of the negative pressure control valve 23, the fuel passage 5.
6 is not supplied with atmospheric air, and a predetermined fuel is supplied to the intake passage 2 as it is.

Next, at high altitudes, the air pressure decreases, so the bellows 13 of the altitude compensation valve 11 extends and the opening 14 is closed.

Therefore, the negative pressure introduced into the diaphragm chamber 17 through the passage 19 is sealed off by the check valve 21, and the diaphragm chamber 17 is maintained at a high negative pressure. As a result, the spring 16 is overcome and the diaphragm 15 is pulled up, the valve 18 is pulled up, and atmospheric air from the atmospheric filter 12 is introduced into the altitude compensation air passage 8.10. By introducing the atmosphere, air is introduced into the fuel in the fuel passage 5.6, suppressing the fuel supply pressure and appropriately thinning the air-fuel ratio.

Of this atmospheric air introduction, the amount of atmospheric air introduced into the slow system fuel passage 6 is controlled by the negative pressure control valve 23 according to one or more operating conditions.

That is, the negative pressure in the intake passage 2 at the position of the negative pressure outlet 31 becomes high negative pressure in an operating range where the throttle valve 3 is opened at a low degree, such as in an idling state, and becomes almost large when the throttle valve 3 is opened. becomes atmospheric pressure. Therefore, when the throttle valve 3 is at a low 1tt1 degree, high negative pressure is introduced into the diaphragm chamber 27 of the negative pressure control valve 23, the valve 29 is lowered against the spring 26, and the atmospheric supply passage 22b is lowered.
is closed, and the introduction of the atmosphere from the bypass passage 22 to the slow system fuel passage 6 is blocked. Therefore, in this state, only the air that has passed through the throttle 9 of the altitude compensation air passage 10 is introduced into the slow system fuel passage 6, and the amount of air introduced is kept small. The cross-sectional area of the throttle 9 is set so that when the intake air amount of the engine is small, such as when the engine is in an idling state, the amount of slow system fuel can be appropriately suppressed by the amount of supplied air. This prevents the air-fuel ratio from becoming too thin when the amount of air is small, and ensures a proper air-fuel ratio.

Conversely, when the throttle valve 3 is opened, the diaphragm chamber 27 becomes almost atmospheric pressure, and the force of the spring 26 pushes up the diaphragm 25 and the valve 29, and the atmosphere introduction passage 2
2a and the atmosphere supply passage 22b are communicated with each other to form the bypass passage 2.
2 will be asked. When the bypass passage 22 opens, in addition to the amount of air introduced by the throttle 9, the atmosphere defined by the throttle 24 is introduced from the bypass passage 22, increasing the amount of air introduced into the slow system fuel passage 6. . As a result, even if the throttle 9 is set according to the case where the amount of intake air is small, due to the addition of atmospheric air from the bypass passage 22,
Even when there is a large amount of intake air, atmospheric air is introduced so that an appropriate air-fuel ratio is achieved, and the amount of fuel supplied to the slow system fuel passage 6 is appropriately adjusted.

Therefore, according to this embodiment, the operating state of the engine is detected by the negative pressure in the intake passage 2 based on the opening degree of the throttle valve 3, and the air introduction gear for altitude compensation to the slow system fuel passage 6 is adjusted depending on the operating state. Since the control is carried out, it is possible to obtain the effect that an appropriate air-fuel ratio can be ensured in any operating range where the amount of intake air differs. As a result, it is possible to ensure good drivability in all driving ranges even at high altitudes, and to reduce harmful emissions such as carbon monoxide and hydrocarbons in the exhaust gas.

[Brief explanation of drawings]

The figure is a schematic configuration diagram of an altitude compensation @ position of an internal combustion engine according to an embodiment of the present invention. 1... Carburetor 2... Intake passage 3... Throttle valve 5... Main fuel passage 6... Slow system fuel passage 7. 9... Throttle 8.10... Altitude compensation air passage 11...
... Altitude compensation valve 17 ... Diaphragm 18 ... Valve 20 ... Throttle 21 ... Check valve 22 ... Bypass passage 22a. ... Atmospheric introduction passage 22b... Atmospheric supply passage 23... Negative pressure control valve 24... Restriction 27... Diaphragm 29... ... Valve 30 ... Negative pressure passage 31 ... Negative pressure outlet

Claims (1)

[Claims] (1) A bypass passage is provided in the altitude compensation air passage leading from the altitude compensation valve that supplies atmospheric air to the fuel passage of the carburetor to the slow system fuel r1 passage of the carburetor when the atmospheric pressure becomes low, and in the bypass passage, An altitude compensator for an internal combustion engine, comprising a negative pressure control valve connected to a negative pressure outlet provided at a throttle valve position of an intake passage and opening and closing the bypass passage in accordance with the negative pressure.