JP2008248840A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of stabilizing combustion with a simple construction and materializing improvement of output and improvement of fuel economy in internal combustion engines using a mixed fuel. <P>SOLUTION: In the engine 1 supplied with a gasoline and ethanol mixed fuel, water is added in a fuel tank 60 storing the mixed fuel, ethanol water is separated and extracted from the mixed fuel, and alcohol water is injected in a suction port during heavy load operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine to which a mixed fuel of gasoline and alcohol is supplied.

In recent years, there is an internal combustion engine (hereinafter simply referred to as an engine) that uses a mixed fuel obtained by mixing gasoline and alcohol.
However, the mixed fuel has a property that gasoline and alcohol are easily separated when water is mixed into the mixed fuel because the hydrophilicity of the alcohol is high. For example, gasoline and ethanol water are completely separated by adding water with a volume ratio of about 0.5% to 10% ethanol mixed gasoline (so-called E10 fuel). For this reason, in an internal combustion engine using a mixed fuel, it is necessary to strictly prevent water from entering the fuel tank, or to perform fuel injection control according to the alcohol concentration, and the configuration and control are complicated. .

In addition, the internal combustion engine using the mixed fuel has a problem that it is difficult to start at a low temperature because combustion at a low temperature tends to be unstable compared to an internal combustion engine using only gasoline.
Therefore, an internal combustion engine start system has been developed that improves the low-temperature startability by separating the mixed fuel by supplying water into the fuel passage at the time of low temperature start of the internal combustion engine and performing fuel injection with only gasoline ( Patent Document 1).
JP 2006-257907 A

However, in the technique disclosed in Patent Document 1, water is supplied into a delivery pipe that is a fuel passage. In such a configuration, gasoline and alcohol separated by slight vibration or the like are agitated, It is difficult to perform accurate gasoline injection. In Patent Document 1, no consideration is given to the treatment of the separated alcohol.
Moreover, in the said patent document 1, although the water tank which stores the water for isolate | separating fuel mixture is provided, how to replenish the water to the said water tank is not considered, but a water tank If the water in the tank runs out and separation of the mixed fuel becomes impossible, there is a problem that combustion becomes unstable and startability deteriorates. However, there is a problem that the work of the user increases when the vehicle user replenishes water.

  The present invention has been made to solve such a problem, and an object of the present invention is to stabilize combustion with an easy configuration in an internal combustion engine using a mixed fuel, and to improve output and An internal combustion engine capable of realizing improvement in fuel consumption is provided.

  In order to achieve the above-described object, in the internal combustion engine according to claim 1, a fuel tank for storing a mixed fuel of gasoline and alcohol, water adding means for adding water into the fuel tank, and water added by the water adding means. Alcohol water supply means for supplying alcohol water separated and extracted from the mixed fuel to the internal combustion engine by adding and residual fuel supply means for supplying residual fuel after the alcohol water is separated and extracted to the internal combustion engine Load condition detecting means for detecting a load condition of the internal combustion engine, operating the residual fuel supply means during normal operation of the internal combustion engine, and at least when a load greater than a predetermined value is detected by the load condition detecting means And a control means for operating the alcohol water supply means.

  The internal combustion engine according to claim 2, wherein the water addition means has a water tank for storing water, and the water tank is provided with an air conditioner provided in a vehicle on which the internal combustion engine is mounted. It is characterized by the fact that the condensed water generated in can be stored.

  In the internal combustion engine according to claim 1 of the present invention using the above-mentioned means, in the internal combustion engine supplied with the mixed fuel of gasoline and alcohol, the mixing is easily made by adding water into the fuel tank in which the mixed fuel is stored. Supply means for separating and extracting the alcohol water from the fuel and supplying the alcohol water and the residual fuel to the internal combustion engine are provided, and the operation is performed by supplying the residual fuel to the internal combustion engine during normal operation. Then, by supplying alcohol water to the internal combustion engine during high load operation, the combustion temperature can be lowered by the latent heat of vaporization of the alcohol water. Thereby, knocking at the time of high load can be suppressed, a high compression ratio of the internal combustion engine can be realized, high output can be achieved, and fuel consumption at low load operation can be improved.

As described above, according to the internal combustion engine of the first aspect of the present invention, in the internal combustion engine to which the mixed fuel is supplied, combustion can be stabilized with an easy configuration, and output and fuel consumption can be improved. can do.
According to the internal combustion engine of claim 2, the water addition means has a water tank, and the water supply by the user of the vehicle is made possible by allowing the condensed water generated by the vehicle air conditioner to be supplied to the water tank. An increase in work can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1, there is shown a schematic configuration diagram of an internal combustion engine according to the present invention.
An engine 1 (internal combustion engine) shown in FIG. 1 is a four-cycle in-line four-cylinder engine compatible with, for example, ethanol 10% mixed gasoline (hereinafter referred to as E10 fuel), and FIG. 1 shows a longitudinal section of one of the cylinders. It is shown. The other cylinders not shown in the figure have the same configuration as the cylinder shown in FIG.

As shown in FIG. 1, the engine 1 is configured by mounting a cylinder head 4 on a cylinder block 2.
A piston 8 is provided in the cylinder 6 formed in the cylinder block 2 so as to be slidable up and down. The piston 8 is connected to the crankshaft 12 via a connecting rod 10. A crank angle sensor 14 for detecting the crank angle of the crankshaft 12 is provided.

A so-called pent roof type slope is formed on the lower surface of the cylinder head 4 corresponding to the cylinder 6, and a combustion chamber 16 is formed surrounded by the lower surface of the cylinder head 4, the cylinder 6, and the upper surface of the piston 8. .
A spark plug 18 is provided at the center of the lower surface of the cylinder head 4 so as to face the combustion chamber 16.

Further, the cylinder head 4 is formed with an intake port 20 from one side of the lower surface of the cylinder head 4 toward one side of the cylinder head 4, and from the other side of the lower surface of the cylinder head 4 to the other side of the cylinder head 4. An exhaust port 22 is formed toward the front.
In addition, the cylinder head 4 is provided with an intake valve 24 that communicates and shuts off the combustion chamber 16 and the intake port 20, and an exhaust valve 26 that communicates and shuts off the combustion chamber 16 and the exhaust port 22.

Further, the cylinder head 4 is provided with a gasoline injection valve 28 (residual fuel supply means) for injecting gasoline into the intake port 20 and an ethanol water injection valve 30 (ethanol water supply means) for injecting ethanol water.
An intake manifold 32 is connected to one side surface of the cylinder head 4 so as to communicate with the intake port 20. The intake manifold 32 is connected to a surge tank 34, and the surge tank 34 is connected to an intake pipe 36.

The intake pipe 36 is provided with an electronic throttle valve 38 for adjusting the intake air amount, an intercooler 40 for cooling the intake air is provided on the upstream side of the intake air, and further, an exhaust flow is provided on the upstream side of the intake air. A compressor of a turbocharger 42 that is driven to supercharge intake air is provided.
An airflow sensor 44 for detecting the intake air amount is provided upstream of the turbocharger 42 and an air cleaner 46 is provided at the intake upstream end of the intake pipe 36.

On the other hand, an exhaust manifold 48 is connected to the other side surface of the cylinder head 4 so as to communicate with the exhaust port 22.
An exhaust pipe 50 is connected to the exhaust manifold 48, and a turbine of a turbocharger 42 that rotates in synchronization with the compressor is provided in the exhaust pipe 50.
Further, the vehicle on which the engine 1 is mounted is provided with a fuel tank 60 that stores E10 fuel.

The fuel tank 60 includes a main tank 62 formed in the upper part and a sub tank 64 formed in the lower part.
Specifically, the fuel tank 60 is in the same shape as the box and has a smaller volume than the main tank 62 (for example, 10% of the main tank volume), and the upper surface of the sub tank 64 communicates with the bottom surface of the box-shaped main tank 62. Is formed. The main tank 62 and the sub tank 64 are partitioned by a baffle plate 66 having a plurality of holes.

  A main pump 70 connected to the gasoline injection valve 28 via a gasoline supply pipe 68 is disposed at the bottom of the main tank 62, and an ethanol water supply pipe 72 is provided at the bottom of the sub tank 64. A sub pump 74 connected to the ethanol water injection valve 30 is provided. The gasoline supply pipe 68 and the ethanol water supply pipe 72 are provided with a filter, a delivery pipe, and the like (not shown).

In addition, a fuel gauge 78 for detecting the amount of fuel in the fuel tank 60 is provided at the upper part of the main tank 62, and a fuel pipe 76 connected to a fuel inlet (not shown) formed on the side wall of the vehicle body is connected. It has been.
One end of a water addition pipe 80 is connected to the upper part of the main tank 62.
The water addition pipe 80 is provided with a check valve 82, a water addition pump 84, and a filter 86 in the middle, and the other end is connected to a water tank 88 that stores water. The water addition pipe 80 has a function of adding water in the water tank 88 into the fuel tank 60 by operating the water addition pump 84 (water addition means).

Further, the water tank 88 has a volume capable of storing 0.5% of water with respect to the fuel storage capacity of the fuel tank 60, for example. A drainage passage 90 for discharging the water is formed.
Further, one end of a condensed water pipe 92 is connected to the upper portion of the water tank 88.
The other end of the condensed water pipe 92 is connected to an evaporator 94 portion of an air conditioner mounted on the vehicle, and has a function of supplying condensed water generated in the evaporator 94 into the water tank 88 when the air conditioner is activated. ing. Although not shown, the water tank 88 is also provided with a replenishing port that can be replenished with water by a vehicle user.

Further, the vehicle is provided with an ECU 96 as a control device for performing comprehensive control including operation control of the engine 1, etc., and the ECU 96 includes a CPU, a memory, a timer counter, and the like. The control amount is calculated and various devices are controlled based on the control amount.
For example, on the input side of the ECU 94, there are various types such as the crank angle sensor 14, the air flow sensor 44, the fuel gauge 78, and an accelerator position sensor (APS) 98 that detects the accelerator opening of an accelerator pedal that performs acceleration / deceleration operation of the vehicle. Sensors are connected (load state detection means). Various devices such as an ignition plug 18, a gasoline injection valve 28, an ethanol water injection valve 30, an electronic throttle valve 38, a main pump 70, a sub pump 74, and a water addition pump 84 are connected to the output side of the ECU 96. Has been.

The ECU 94 controls fuel injection and ignition to each cylinder 4 based on information acquired from the various sensors, and performs control to separate and extract ethanol water from the supplied E10 fuel.
Hereinafter, the operation of the internal combustion engine according to the present invention configured as described above will be described.
E10 fuel is supplied from the fuel supply port, and the fuel supply amount in the fuel tank 60 is detected by the fuel gauge 78, and the ECU 96 operates the water addition pump 84 and is stored in the water tank 88 according to the detection result. Water is added into the fuel tank 60. Note that the amount of water added to the fuel tank 60 is an amount capable of separating all of the supplied E10 fuel into gasoline and ethanol water, that is, about 0.5% of the above-mentioned constant amount.

  The E10 fuel to which water has been added is separated such that ethanol water having high hydrophilicity and higher density than gasoline is located on the lower side and gasoline is located on the upper side. Here, the amount of ethanol may be detected by a float floating on the boundary surface using the difference in specific gravity between ethanol water and gasoline. By accurately detecting the amount of ethanol, it is possible to prevent the main pump 70 from sucking up the ethanol water due to the ethanol water in the sub tank 64 entering the main tank 62. For example, if the amount of ethanol water is likely to exceed the capacity of the sub tank 64, it is possible to perform control such that a large amount of ethanol water is injected.

Then, the ethanol water separated downward passes through the hole of the baffle plate 66 and is stored in the sub tank 64. The ethanol water stored in the sub tank 64 is partitioned from the main tank 62 by the baffle plate 66, so that fluctuations in the oil level due to vehicle vibration or the like are suppressed, and stirring with gasoline is prevented.
On the other hand, the amount of water in the water tank 88 is reduced or emptied by adding water into the fuel tank 60, but condensed water is generated in the evaporator 94 with the operation of the air conditioner device, so that the condensed water pipe 92 passes through the condensed water pipe 92. Thus, the condensed water is supplied into the water tank 88.

  In order to secure the condensed water here, for example, even when the switch of the air conditioner is inactive, the condensed water in the evaporator 94 is activated by operating the compressor of the air conditioner with the regenerative braking torque at the time of vehicle deceleration. It is preferable to promote the generation. Moreover, when the replenishment of water by condensed water is not in time for the next refueling, the user can replenish water.

The ECU 96 calculates the engine load based on the accelerator opening detected by the APS 98 and the intake air amount detected by the airflow sensor 44, and calculates the engine speed from the crank angle detected by the crank angle sensor 14. The fuel injection control and the ignition control are performed according to the calculated engine load and engine speed.
Specifically, the gasoline injection amount, the injection timing, and the ignition timing are set based on a map corresponding to the engine load and engine speed stored in the ECU 96, and the gasoline injection valve 28 and the ignition plug 18 are controlled according to the set values. I do.

The ECU 96 operates the sub pump 74 to supply the ethanol water stored in the sub tank 64 to the ethanol water injection valve 30 in addition to gasoline injection during high load operation where the engine load is a predetermined load or more. Control is performed so that ethanol water is also injected into the intake port 20 from the ethanol water injection valve 30.
By injecting ethanol water into the intake port 20 during high load operation in this way, the combustion temperature can be lowered by the latent heat of vaporization of the ethanol water, and knocking can be suppressed.

Therefore, it is possible to increase the compression ratio of the engine 1 and increase the output, and to improve the fuel efficiency during low load operation.
Further, in an E10 fuel-compatible engine, operation by gasoline injection with E10 fuel separated is performed, so that it is not necessary to perform control according to the alcohol concentration and prevention of water intrusion into the fuel tank as in the prior art. The deterioration of can also be eliminated.

Further, a sufficient amount of ethanol water can be ensured only by adding a small amount of water of about 0.5% to the E10 fuel that is originally easily separated.
Furthermore, since the water to be added to the E10 fuel can be replenished by the condensed water generated in the evaporator 94 of the air conditioner, it is possible to prevent an increase in water replenishment work by the vehicle user.

As described above, the internal combustion engine according to the present invention can stabilize combustion with an easy configuration in an internal combustion engine using a mixed fuel, and can realize an improvement in output and an improvement in fuel consumption.
Although the description of the embodiment of the internal combustion engine according to the present invention is finished above, the embodiment is not limited to the above embodiment.

For example, as a modification, as shown in FIG. 2, a branch passage 100 branched from the ethanol water supply pipe 72 of the above embodiment to the water tank 88 is formed, and ethanol water controlled by the ECU 96 is provided in the branch passage 100. The control valve 102 is provided.
When the sub pump 74 is operated, the ethanol water control valve 102 is opened to supply ethanol water into the water tank 88.

Thus, by supplying ethanol water to the water in the water tank 88, corrosion and freezing of the water in the water tank can be prevented.
As another modified example, although not shown, a supercharging pressure passage that connects the intake pipe 36 and the upper surface of the water tank 88 downstream of the turbocharger 42 of the above embodiment is formed, and the supercharging pressure passage Is provided with a supercharging pressure control valve controlled by the ECU 96, and the water addition pump 84 in the above embodiment is eliminated.

Then, after the E10 fuel is refueled, the supercharging pressure control valve is opened when the supercharging pressure by the turbocharger 42 is equal to or higher than a predetermined pressure, so that the water in the water tank 88 is brought into the fuel tank 60 by the supercharging pressure. Add to.
Thereby, it can be set as the simple structure which does not require the water addition pump 84. FIG.
In addition, for example, the engine 1 in the above embodiment is an engine that supports E10 fuel as a mixed fuel, but the present invention can also be applied to engines that use other alcohol mixed fuels.

  In the above embodiment, the sub tank 64 of the fuel tank 60 has a box shape and the volume is 10% of the main tank volume. However, the shape and volume are not limited to this, and the separated alcohol water can be sufficiently stored. Anything is acceptable. For example, when the mixed fuel to be supplied is a 20% ethanol mixed fuel, the volume of the sub tank is preferably 20% or more of the main tank.

Moreover, in the said embodiment, although the volume of the water tank 88 is 0.5% with respect to the fuel storage possible amount of the fuel tank 60, the volume of the said water tank 88 is not restricted to this, For example, it is larger The volume may be used.
Moreover, although the engine 1 in the said embodiment is what injects gasoline in an intake port by the gasoline injection valve 28, even if a gasoline injection valve injects gasoline directly in a combustion chamber, for example, I do not care. Also, the ethanol water injection valve may be configured to inject ethanol water directly into the combustion chamber.

  In the above embodiment, the mixed fuel (E10 fuel) is completely separated into gasoline and ethanol water. However, the present invention is not limited to such a configuration. For example, a part of ethanol water is separated and extracted from the mixed fuel. A configuration may be adopted in which operation is performed with the remaining mixed fuel during operation, and ethanol water is also supplied during high-load operation. In this case, it is preferable to provide an alcohol concentration sensor or the like for detecting the alcohol concentration in the residual fuel supply means.

1 is a schematic configuration diagram of an internal combustion engine according to the present invention. It is a schematic block diagram which shows the principal part of a modification.

Explanation of symbols

1 engine (internal combustion engine)
14 Crank angle sensor (load state detection means)
28 Gasoline injection valve (residual fuel supply means)
39 Ethanol water injection valve (ethanol water supply means)
44 Air flow sensor (load state detection means)
60 Fuel tank 62 Main tank 64 Sub tank 66 Baffle plate 70 Main pump (residual fuel supply means)
74 Sub pump (ethanol water supply means)
78 Fuel gauge 80 Water addition pipe (water addition means)
84 Water addition pump (water addition means)
88 Water tank (water addition means)
94 Evaporator 96 ECU (control means)
98 Accelerator position sensor (APS) (load state detection means)

Claims (2)

A fuel tank for storing a mixed fuel of gasoline and alcohol;
Water addition means for adding water into the fuel tank;
Alcohol water supply means for supplying alcohol water separated and extracted from the mixed fuel to the internal combustion engine by adding water by the water addition means;
Residual fuel supply means for supplying residual fuel after the alcohol water is separated and extracted to the internal combustion engine;
Load state detecting means for detecting a load state of the internal combustion engine;
Control means for operating the residual fuel supply means during normal operation of the internal combustion engine and for operating at least the alcohol water supply means when a load of a predetermined level or more is detected by the load state detection means. An internal combustion engine. The water adding means has a water tank for storing water,
The internal combustion engine according to claim 1, wherein condensed water generated by an air conditioner provided in a vehicle on which the internal combustion engine is mounted can be stored in the water tank.

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