JPS6254987B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine fuel supply device that supplies a mixed fuel made by mixing alcohol and gasoline to an engine from a carburetor.

In recent years, with the aim of reducing gasoline consumption,
Attempts have been made to run an engine using a mixed fuel made by mixing this gasoline with alcohol at a predetermined ratio (for example, the 2nd revised Lecture on Internal Combustion Engines published by Yokendo on May 20, 1961). (See pages 787-788).

Further, in general, the air-fuel ratio of the air-fuel mixture required to ensure smooth startability and warm-up of the engine differs between before complete explosion (before starting) and after complete explosion (after starting) of the engine. In order to obtain a mixture with an appropriate air-fuel ratio before and after the complete combustion of the engine, it is necessary to correct the opening degree of the choke valve of the carburetor in accordance with the complete combustion of the engine. For this reason, conventionally, a complete explosion correction mechanism has been developed that utilizes the intake negative pressure generated by the complete explosion of the engine to forcibly open the choke valve by a certain opening after the complete explosion, making the air-fuel ratio leaner than before the complete explosion. It is installed in the carburetor to obtain an appropriate air-fuel ratio before and after the engine complete combustion, ensuring good startability and warm-up performance.

However, when using a mixed fuel of gasoline and alcohol as mentioned above,
There is a problem in that when the alcohol concentration of this mixed fuel increases, engine startability and warm-up performance deteriorate.

In other words, the alcohol concentration in the mixed fuel varies due to changes in the mixing ratio when gasoline and alcohol are mixed, as well as due to factors such as the occurrence of alcohol separation, and if the alcohol concentration rises above the set value due to some factor. There is. When the alcohol concentration increases, alcohol has a smaller stoichiometric air-fuel ratio than gasoline, so it is basically necessary to enrich the air-fuel ratio, and alcohol has a significantly higher latent heat of vaporization than gasoline, so it is especially difficult to start cold. Sometimes it is necessary to enrich the air-fuel ratio even when the air-fuel mixture temperature is difficult to rise and vaporization is poor.

Therefore, a mixed fuel containing alcohol and gasoline at a predetermined ratio has good starting performance and
In a carburetor equipped with a complete explosion correction mechanism in which the correction amount of the choke valve opening at the time of complete explosion is set so as to provide warm-up performance, when the alcohol concentration exceeds the set value as described above, When the combustion correction mechanism opens the combustion valve by the set correction amount after the engine complete combustion, the supplied air-fuel ratio becomes over lean compared to the required air-fuel ratio which shifts to the rich side as the alcohol concentration increases. Therefore, there is a problem in that the engine cannot be warmed up properly after a complete explosion.

In addition to the above, the air-fuel ratio of the air-fuel mixture required to ensure smooth starting and warm-up of the engine varies depending on the outside temperature, and also differs before and after starting the engine. It also changes depending on the progress of the machine, so in order to obtain a mixture with an appropriate air-fuel ratio that corresponds to such changes in conditions, it is necessary to control the opening of the carburetor's check valve in response to changes in conditions. There is.

Therefore, in the carburetor that supplies fuel to the engine,
An automatic chiyoke system that has a bimetal that adjusts the closing force of the chiyoke valve according to the ambient temperature and controls the degree of opening of the chiyoke valve, and an electric heater that heats this bimetal during engine operation and gradually opens the chiyoke valve. When starting the engine in a cold state, the engine valve is fully closed, and as the engine warms up after startup, the engine valve is gradually opened to ensure good starting and warm-up performance. A bimetal that adjusts the closing force of the check valve according to the ambient temperature and controls the opening of the check valve, and a bimetal that uses the intake negative pressure generated when the engine starts to reduce the closing force of the bimetal by a certain amount when the engine starts. The carburetor is equipped with a declination correction mechanism that makes the air-fuel ratio leaner than before starting, and obtains the appropriate air-fuel ratio depending on the ambient temperature and before and after starting the engine, ensuring good starting performance and warm-up performance. However, these also have similar problems when the alcohol concentration exceeds a set value.

The present invention has been made in view of this point, and when the alcohol concentration exceeds the set value and the opening degree of the throttle valve is set at a normal alcohol concentration, the valve becomes over lean and good warm-up performance cannot be obtained. It is an object of the present invention to provide a fuel supply device for an engine that can improve warm-up performance by reducing the valve opening and enriching the air-fuel ratio.

In order to achieve the above object, the present invention detects alcohol concentration in a fuel supply device for an engine that is equipped with a carburetor having a choke valve and supplies a mixed fuel made by mixing alcohol and gasoline from the carburetor. alcohol concentration sensor,
A control device is provided which corrects and controls the opening degree of the cheese valve in response to the output of the alcohol concentration sensor, and when the alcohol concentration exceeds a set value, the operation of the cheese valve opening degree in the opening direction is restricted. It is characterized by:

Hereinafter, embodiments of the present invention, particularly embodiments of a fuel supply system for an engine equipped with a carburetor having a complete combustion correction mechanism that opens a combustion valve to a certain degree after the engine complete combustion, will be described with reference to the drawings.

Embodiment 1 In FIG. 1, 1 is a carburetor that supplies a mixed fuel of alcohol and gasoline, and 2 is a chiyoke valve rotatably supported in the intake passage 3 of the carburetor 1 by a chiyoke valve shaft 4. , 5 is a check valve lever, 5a, which is integrally provided at one end of the check valve shaft 4.
Reference numeral 6 denotes a groove provided in the tip of the engine valve lever 5 in the shape of an arc with the engine valve shaft 4 as the center, and 6 represents a complete combustion correction mechanism that opens the engine valve 2 to a certain opening after the engine has completely exploded.

The complete explosion correction mechanism 6 has a diaphragm device 7 that is operated by intake negative pressure, and the diaphragm device 7 has a distal end that connects to the groove of the choke valve lever 5.
It has a negative pressure chamber 7c and an atmospheric chamber 7d defined by a diaphragm 7b to which the rod 7a that engages with the rod 7a is connected.
A spring 7e that biases a in the projecting direction is compressed. Further, the negative pressure chamber 7c is connected to the other end of a negative pressure passage 8 whose one end is open to the intake passage 3 downstream of a throttle valve (not shown), and the magnitude of the intake negative pressure introduced into the negative pressure chamber 7c is Accordingly, the diaphragm 7b is configured to be biased by a predetermined amount against the spring force of the spring 7e. An atmosphere opening port 8a is provided in the middle of the negative pressure passage 8 to reduce the magnitude of the intake negative pressure introduced into the negative pressure chamber 7c.

The above-mentioned complete explosion correction mechanism 6 is configured such that, before the engine complete explosion, the diaphragm device 7 is not operating due to the small intake negative pressure, and the chiyoke valve 2 is in a fully closed state, which is activated by the complete engine explosion. Then, the increased intake negative pressure is applied to the diaphragm device 7.
The diaphragm 7b is biased by the rod 7a, and the rod 7a pulls the choke valve lever 5 to open the choke valve 2, which is in the fully closed state, by a certain correction opening degree, thereby correcting for a complete explosion. The tip of the rod 7a slides within the groove 5a to allow rotation of the check valve lever 5 when the check valve 2 opens further beyond this corrected opening degree.

Further, 9 is an alcohol concentration sensor that detects the alcohol concentration of the mixed fuel, and 10 is a control device that controls the correction amount of the complete explosion correction mechanism 6. The control device 10 receives an output from an alcohol concentration sensor 9 and a solenoid valve 11 that opens and closes an atmosphere opening 8a provided in the middle of the negative pressure passage 8 and adjusts its opening area, and operates according to the detected alcohol concentration. and a control circuit 12 for operating the electromagnetic valve 11, and when the detected alcohol concentration exceeds a preset value, the electromagnetic valve 11 opens and the alcohol is introduced into the negative pressure chamber 7c of the diaphragm device 7. By reducing the intake negative pressure, the correction amount of the complete explosion correction mechanism 6 is reduced by a set value corresponding to the decrease in the negative pressure.

Incidentally, the alcohol concentration sensor 9 is as follows:
For example, a device that detects the alcohol concentration of the mixed fuel in the float chamber of the carburetor by detecting a change in dielectric constant and outputs a detection signal corresponding to the alcohol concentration may be used as appropriate.

To explain the operation of the above embodiment, when the combustion valve 2, which is in the fully closed state in response to a complete explosion of the engine, is opened by a predetermined correction amount by the complete explosion correction mechanism 6, the alcohol concentration sensor 9 detects the alcohol content of the mixed fuel. When the concentration is low and has not reached the set value, the control device 10 operates the complete explosion correction mechanism 6 with a predetermined (normal) intake negative pressure, and the
Compensate for complete explosion by opening the valve a certain amount.

On the other hand, when the alcohol concentration detected by the alcohol concentration sensor 9 becomes a high concentration higher than the set value, the control device 10 controls the complete explosion correction mechanism 6 to maintain a low negative pressure by releasing a part of the introduced intake air negative pressure to the atmosphere. is operated to reduce the correction amount to a set value, thereby performing a complete explosion correction so that the fully closed valve 2 is opened at a correction opening smaller than the normal correction opening. Therefore, the opening degree of the cheese valve 2 after a complete engine explosion is smaller than in the normal case, that is, the opening degree is close to the fully closed state. With respect to the required air-fuel ratio, which is shifting toward the rich side as the fuel temperature increases, the air-fuel ratio that becomes over lean is enriched and corrected to the required air-fuel ratio, and good warm-up performance can be obtained.

Example 2 In this example shown in FIG. 2, the complete explosion correction mechanism 1
3 has a dual diaphragm device 14.
The diaphragm device 14 includes a first diaphragm 1
4a and a second diaphragm 14b, the first diaphragm 14a has a first negative pressure chamber 14c, a second negative pressure chamber 14d, and an atmospheric chamber 14e. 5a is fixed, and the first diaphragm 1
4a and the second diaphragm 14b are interlocked by engagement between an engagement pin 14g provided upright on the second diaphragm 14b and an engaged body 14h provided protruding from the first diaphragm 14a. Further, first and second springs 14i and 14 are provided in the first and second negative pressure chambers 14c and 14d, respectively, to urge the first and second negative pressure chambers 14c and 14d in the expansion direction.
j is reduced. Further, the first and second negative pressure chambers 14c and 14d are connected to first and second negative pressure passages 15 and 16, each of which has one end open to the intake passage 3 downstream of a throttle valve (not shown). At the same time, an atmosphere opening 15a is opened in the middle of the first negative pressure passage 15 communicating with the first negative pressure chamber 14c formed between the first diaphragm 14a and the second diaphragm 14b. The atmosphere opening port 15a of the first negative pressure passage 15 is opened and closed based on the command of the control circuit 12 which receives the output of the alcohol concentration sensor 9 by the solenoid valve 11 of the control device 10 similar to the previous example, and the alcohol concentration is set. When the pressure exceeds the value, the atmosphere opening port 15a is opened and the first negative pressure passage 15 is opened.
is configured to be open to the atmosphere.

The rest is the same as the previous example, and the same structures are given the same reference numerals and their explanations will be omitted.

To explain the operation of this example, in response to the complete explosion of the engine, the complete explosion correction mechanism 1
3, when the alcohol concentration of the mixed fuel detected by the alcohol concentration sensor 9 is low and has not reached the set value, the control device 10 controls the solenoid valve 11 to open the first negative pressure passage. 15
The atmosphere opening 15a is closed. Therefore, intake negative pressure is introduced into both the first and second negative pressure chambers 14c and 14d of the diaphragm device 14 of the complete explosion correction mechanism 13, and the deflection of the first diaphragm 14a and the deflection of the second diaphragm 14b are adjusted. It operates with the added amount of deviation, and the combustion valve 2 is opened by a certain opening degree corresponding to this amount of deviation to perform complete explosion correction.

On the other hand, when the alcohol concentration detected by the alcohol concentration sensor 9 reaches a high concentration higher than the set value, the control device 10 completely opens the atmosphere opening port 15a of the first negative pressure passage 15 using the solenoid valve 11. , the intake negative pressure acting on the first negative pressure chamber 14c of the diaphragm device 14 is released to the atmosphere, and the first negative pressure chamber 1
4c is the atmospheric pressure. Therefore, the diaphragm device 14 of the complete explosion correction mechanism 13 has its second
Intake negative pressure is introduced only into the negative pressure chamber 14d, and the second diaphragm 14b is actuated by the amount of deflection (the first diaphragm 14a is interlocked with the engaging pin 14g and the engaged body 14h), and the yoke valve 2 is Complete explosion correction is performed by opening the opening according to the reduced amount of deviation. In other words, by the amount of the decrease in the deflection of the first diaphragm 14a caused by disabling the introduction of intake negative pressure into the first negative pressure chamber 14c, the fully closed valve 2 is changed to a corrected opening smaller than the normal corrected opening. This corrects the complete explosion so that it opens at 100 degrees, and enriches the air-fuel ratio.

In this example, since the set value for reducing the correction amount of the complete explosion correction mechanism 13 by the control device 10 is set in the complete explosion correction mechanism 13 and does not need to be adjusted by the solenoid valve 11, its control is better than in the previous example. It becomes easier.

Therefore, according to the present invention as described above, in a fuel supply device for mixed fuel equipped with a carburetor having a choke valve, the choke valve of the carburetor is opened in response to the output of the alcohol concentration sensor that detects the alcohol concentration. When the alcohol concentration exceeds a set value, the control device that corrects and controls the alcohol concentration restricts the operation of the alcohol valve opening in the opening direction. When the setting becomes over lean and good warm-up performance cannot be obtained, warm-up performance can be improved by reducing the opening of the choke valve and enriching the air-fuel ratio. It has the advantage of being able to deal with problems effectively.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, with FIG. 1 being a schematic diagram showing a first embodiment, and FIG. 2 being a schematic diagram showing a second embodiment. DESCRIPTION OF SYMBOLS 1... Carburetor, 2... Chiyoke valve, 3... Intake passage, 4... Chiyoke valve shaft, 5... Chiyoke valve lever, 6, 13... Complete explosion correction mechanism, 7, 14...
Diaphragm device, 8, 15... Negative pressure passage, 8
a, 15a... Atmosphere opening port, 9... Alcohol concentration sensor, 10... Control device, 11... Solenoid valve, 12... Control circuit.

Claims (1)

[Claims] 1. In a fuel supply system for an engine that is equipped with a carburetor having a choke valve and that supplies a mixed fuel made by mixing alcohol and gasoline from the carburetor, an alcohol concentration sensor that detects the alcohol concentration, and an alcohol concentration sensor that detects the alcohol concentration sensor are provided. An engine characterized in that a control device for correcting and controlling the opening degree of the Chiyork valve in response to the output is provided, and the operation of the opening degree of the Chiyork valve in the opening direction is restricted when the alcohol concentration is higher than a set value. fuel supply system.