JPH06173787A - Hc reducing device for engine - Google Patents

Abstract

PURPOSE:To provide an engine HD reducing device which can enhance the countermeasure for HC (evaporated fuel) for an engine, and which can be easily mounted on any of various kinds of engines. CONSTITUTION:An engine HC reducing device is provided with a return line pipe line 12 through which fuel flowing out from a fuel tank 9 is returned into the tank, a thermoelectric element 17 which constitutes a cooling means for a canister 14 for adsorbing evaporated fuel, a feed pipe line 8 for feeding fuel from the fuel tank 9 into an engine by means of a pump 10, an intake-air port 6 and a thermoelectric element 18 constituting a heating means for an exhaust pipe 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reducing HC (hydrocarbon) emitted from a fuel supply system or an exhaust system of an engine.

[0002]

2. Description of the Related Art As a conventional technique for reducing HC in automobile engines and the like, for example, the exhaust pipe is made of stainless steel instead of cast iron to lower the thermal conductivity of the pipe and suppress the heat release from the pipe for combustion. A technique of burning HC that has not reacted in the chamber to some extent inside the exhaust pipe, and as disclosed in JP-A-1-113567, the canister is cooled in order to enhance the adsorption effect of the canister that adsorbs the evaporated fuel. A technique of using a refrigerant of an air conditioner as a means for performing the operation, and JP-A-59-59
As disclosed in Japanese Patent Laid-Open No. 101573/1998, utilizing the direction control of the thermoelectric element and its current, the air taken into the engine is heated at the time of cold start to promote the vaporization of the air-fuel mixture, and after warming up. At the time of cold start of the engine, the tip of the fuel injection valve is utilized by utilizing the technique of cooling to increase the charging efficiency of the intake air and the thermoelectric element and its current direction control as disclosed in Japanese Patent Laid-Open No. 2-40075. The fuel in the fuel passage of the nozzle part of is heated to promote fuel atomization during cold start,
A technique has been proposed in which after the engine is stopped, the fuel in the vicinity of the nozzle of the fuel injection valve is cooled to suppress fuel evaporation.

When the above thermoelectric element is used as heating or cooling means, there is an advantage that power consumption can be reduced.

Further, although it is different from the HC reduction, JP-A-61
As disclosed in Japanese Laid-Open Patent Publication No. 87961, in order to effectively utilize a thermoelectric element as a power generating element utilizing exhaust heat, one thermoconductive surface of a thermoelectric module is heated in close contact with an exhaust gas passage wall to heat the other. There is a type in which the power generation effect is enhanced by exposing the conductive surface to the air-fuel mixture passage and cooling it by the latent heat of vaporization or air flow of the gasoline of the air-fuel mixture.

[0005]

The regulations on HC (unburned components) contained in the exhaust gas of automobiles and HC (evaporated fuel) leaking from the fuel tank and its feed line are becoming stricter year by year.

Therefore, conventional passive techniques (eg,
As mentioned above, it is expected that it will be difficult to comply with the strict regulations on HC that will be imposed in the near future with the technique of replacing the exhaust pipe with a cast iron pipe and using a stainless steel pipe, and there is an urgent need to develop a technique that can satisfy this regulation. It is said to be an issue.

Therefore, as described above, the technique of cooling the canister to suppress the emission of the evaporated fuel, and the thermoelectric element are used to warm the fuel near the fuel injection valve at the cold start to promote the vaporization of the air-fuel mixture. Although technologies etc. have been proposed, in the former case, since the refrigerant of the air conditioner is used as the cooling means, it is necessary to add refrigerant pipes, etc., and the device becomes large, and in the latter case, the engine housing is used. The mounting portion of the fuel injection valve must be of a fuel injection valve specification with a thermoelectric element, and cannot be applied to an engine without such specification.

The present invention has been made in view of the above points, and an object thereof is to further improve HC reduction measures for an engine and to easily mount the HC on any engine.
To provide a reduction device.

[0009]

In order to achieve the above-mentioned object, the present invention basically proposes the following means for solving the problems.

First, in the fuel supply system of the engine,
At least one of the return line piping for returning the fuel discharged from the fuel tank to the fuel tank and the canister for adsorbing the fuel evaporated in the fuel tank is provided with a cooling means constituted by a thermoelectric element (Peltier element). The first problem solving means).

The other is to provide a heating means constituted by a thermoelectric element (Peltier element) in at least one of a feed line pipe for supplying fuel to the engine from a fuel tank by a pump and an exhaust line pipe of the engine. (This is the second means for solving problems).

The other is a fuel supply system for an engine, which comprises a feed line for supplying fuel to the engine from a fuel tank by a pump and a return line for returning a part of the fuel in the feed line to the fuel tank again. The pipes of the line and the return line are arranged adjacent to each other with a thermoelectric element (Peltier element) interposed therebetween.
Of the thermoelectric element, a heat absorbing surface generated when an electric current is passed is brought into close contact with a pipe of the return line, and a heat generating surface is brought into close contact with a pipe of the feed line, thereby constituting a cooling means of the return line and the feed line ( This is the third means for solving problems).

[0013]

Operation of the first problem solving means: When the return line for returning the fuel to the fuel tank is cooled, the temperature rise of the fuel tank can be suppressed and the evaporation of the fuel can be suppressed. Also, cooling the canister increases the adsorption efficiency of evaporated fuel,
Leakage and release of evaporated fuel (HC) can be reduced.

Such cooling is performed by utilizing the Peltier effect when the thermoelectric element is energized. However, these pipes and the case itself are provided on the pipe wall of the return line system and the case outside the canister. Since the modularized thermoelectric element can be easily attached without modification, the HC reducing apparatus can be easily mounted. In addition, the power consumption of the thermoelectric element is low.

Operation of the second means for solving the problems: When the heating means composed of a thermoelectric element is provided in the feed line pipe of the fuel supply system, the vaporization of the fuel can be promoted, the air-fuel mixture can be satisfactorily generated, and the combustion efficiency can be improved. Thus, HC in the exhaust gas can be reduced.

Further, by heating the exhaust pipe, it is possible to suppress the temperature decrease of the exhaust gas, burn unreacted HC in the exhaust pipe, and reduce the HC contained in the exhaust gas.

Since the thermoelectric element can be easily attached to the pipe of the fuel feed line and the exhaust pipe, a modularized thermoelectric element can be easily attached around the pipe.
Improves mountability. Since these heating means are composed of thermoelectric elements, the power consumption is less than that for heating a heater such as a nichrome wire.

Operation of the third means for solving the problems: When an electric current is applied to the thermoelectric element, one surface of the thermoelectric element module serves as a heat absorbing surface to cool the return line in the fuel supply system, and the other surface serves as a heat generating surface. To heat the feed line.

Therefore, it is possible to effectively reduce HC while reducing the cost of cooling / heating means by suppressing the evaporated fuel by cooling the return line and forming the air-fuel mixture by heating the feed line by sharing the thermoelectric element. It can be planned.

[0020]

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

FIG. 1 shows a basic system of an automobile engine to which the present invention is applied.

In this embodiment, 1 is an engine, and its intake system piping 2 is an air cleaner 3, an air flow sensor 4,
A surge tank 5 is provided, and a fuel injection valve 7 is provided at each intake port 6.

Reference numeral 8 is a pipe for the fuel supply system feed line.
The fuel from the fuel tank 9 is fed to each fuel injection valve 7 via the pump 10. The fuel in the feed line is maintained at a predetermined fuel pressure by the pressure regulator 11, and the fuel not injected is returned to the fuel tank 9 through the pipe 12 of the return line.

The evaporated fuel in the fuel tank 9 is guided to the canister 14 via the pipe 13 and adsorbed by the canister 14.

Reference numeral 15 is an engine exhaust pipe.

On the outer wall of the return line pipe 12 and the canister 14, the cooling means 1 composed of a thermoelectric element is provided.
7 are attached respectively. On the other hand, a heating means 18 constituted by a thermoelectric element is attached to each of the feed line pipe 8, the intake port 6 and the exhaust pipe 15 of the fuel supply system.

As shown in FIG. 16, the thermoelectric element used as such cooling or heating means is a P-type element 52 and an N-type element.
A module is constructed by joining the mold element 53 and connecting them electrically via the electrode 41. 42 is an insulator and 54 is a power supply. When an electric current is passed from the N-type to the P-type, one contact (upper side in the figure) becomes the heat absorbing part due to the Peltier effect, and the other contact (lower side in the figure) becomes the heat generating part.
When a current is passed from the P-type to the N-type, the heat absorbing portion and the heat generating portion are reversed. Thereby, the heat absorbing part can be used as the electronic cooling means 17, and the heat generating part can be used as the electronic heating means 18.

By heating at least one of the feed line pipe 8 and the intake port 6 by the heating means 18, the vaporization for forming the air-fuel mixture is promoted, the combustion efficiency is enhanced, and the HC in the exhaust gas can be reduced. . Furthermore, by providing the heating means 18 in the exhaust pipe 15, it is possible to prevent the temperature of the exhaust gas from decreasing and to burn unreacted HC, and in this case as well, the amount of HC remaining in the exhaust gas can be reduced.

On the other hand, the cooling means 17 provided in the return line 12 enables cooling of the fuel whose temperature rises during engine operation. Therefore, the evaporation / leakage of fuel from the fuel tank 9 which is not completely sealed or the fuel system connected to it can be suppressed.

Further, the cooling means 1 provided in the canister 14
7, the adsorption efficiency of the evaporated fuel is increased. In particular, inside the canister 14 that adsorbs the evaporated fuel, the reaction heat at the time of adsorption reduces the adsorption rate of the canister, and the canister 14
This causes evaporation and leakage of fuel (HC) from the outside to the outside, and such a situation can be prevented by cooling the canister.

2 and 3 show an example in which a thermoelectric element constituting a heating means 18 is provided in the feed line pipe 8. The thermoelectric element 18 in which a P-type element and an N-type element are combined is modularized into a flat plate shape, This thermoelectric element module 18 is φ1
A large number of them are arranged on the outer periphery of the pipe 8 of the feed line of about 0 mm via polygonal spacers 20, and these thermoelectric element modules 18 are covered with a cover 21. In the case of an ordinary passenger car, if the length of the thermoelectric element in the pipe direction is about 30 cm and an electric power of about 0.1 kW is applied, the fuel temperature can be raised by 10 to 15 ° C.

As a result, the combustion efficiency is increased, so that it is not necessary to supply additional fuel, and HC in the exhaust gas can be reduced. Further, when the thermoelectric element is supplied with electric power, one end of the element can generate heat several times as much as the supplied electric power. This is because the thermoelectric element absorbs heat from the other end, and the sum of the input power and the absorbed heat appears as heat generation at one end of the element. Therefore, compared to heating a heater such as a heating wire, the same amount of heat generation can be secured with a smaller amount of power, and a heating system with less power consumption can be configured.

4 and 5 show a modification of the heating means 18. In this example, the P-type element 52 and the N-type element 53 that form the thermoelectric element are formed in an annular shape, and these elements 52, 5
3 is fitted and attached to the outer periphery of the feed line pipe 8. According to this embodiment, the thermoelectric element can be easily mounted even if the feed line is bent to some extent in addition to the above-mentioned embodiments.

FIG. 6 shows a thermoelectric element 1 around the intake port 6.
In the example in which 8 is attached, 23 is a lead wire. In this case as well, since the vaporization rate of the fuel can be increased, the HC in the exhaust gas can be reduced for the reasons already described.

In FIG. 7, a thermoelectric element (heating means) is provided in the exhaust pipe 15.
18 is an example in which 18 is attached. The module configuration of the thermoelectric element 18 is the same as that of the embodiment shown in FIGS.
In general, the thermal conductivity of thermoelectric element materials is smaller than that of metals by one to two orders of magnitude. Therefore, by mounting a thermoelectric element, the temperature drop of exhaust gas can be suppressed, but by heating the exhaust pipe 15, unreacted. It is possible to burn HC. In particular, this effect is great at the time of starting when the pipe is not sufficiently warmed, and HC in the exhaust gas can be reduced.

8 and 9 show the return line piping 1
2. A thermoelectric element (cooling means) around the spacer 2 via a spacer 25.
The heat radiation element 24 is mounted on the heat generating side of the thermoelectric element 17 to enhance the cooling effect. Similarly to the feed line, the return line 12 has a diameter of about 10 mm, and the length of the thermoelectric element in the pipe direction is 30 cm.
When the electric power of about 2 kW is applied, the temperature rise of the fuel tank can be suppressed and the evaporation / leakage of HC can be reduced.

In FIG. 10, a thermoelectric element (cooling means) 17 is attached to the canister 14, and a radiation fin 24 is attached to the thermoelectric element 17. The canister 14 uses activated carbon 26 to adsorb the evaporated fuel. In the case of an ordinary passenger car class canister, the heat generation amount is at most about 0.3 kw, and by applying about 0.1 kw of electric power to the thermoelectric element, it is possible to prevent the adsorption efficiency of the canister from decreasing due to heat generation.

11 and 12 show another application example of the present invention. In this embodiment, feed line and return line pipes 8 and 12 are arranged adjacent to each other with a thermoelectric element 27 interposed therebetween. Then, the heat absorbing surface (cooling surface) of the thermoelectric element 27, which is generated when an electric current is applied, is closely attached to the return line pipe 8 via the spacer 28, and the heat generating surface (heating surface) is attached to the feed line pipe 12 by the spacer 28. All of these elements are covered with a cover 29 as a unit by closely contacting each other.

According to the present embodiment, since the cooling and heating means for the return line and the feed line is constituted by one thermionic module, the apparatus can be made compact and the number of parts can be reduced to reduce the cost.

FIG. 13 is a block diagram showing an example of a control circuit for thermoelectric elements used for the heating means and cooling means.

In the present embodiment, the control circuit 32 supplies the electric power from the storage battery 33 to the thermoelectric element (heating means) 1 based on the signal from the temperature sensor 31 mounted on the feed line, the exhaust pipe, or the like.
8 is supplied. For example, when heating a feed line, an exhaust pipe, an intake pipe, etc., if they are below a set temperature, electric power is supplied to the thermoelectric element. etc,
Power can be saved by operating the thermoelectric element only when vaporization is required.

Also, when the thermoelectric element is used as a cooling means for a canister, a return line, etc., a temperature sensor is used in the same manner as described above. For example, as shown in FIG. Then, power can be supplied to the thermoelectric element and the canister and the return line can be cooled to the minimum necessary to save power.

FIG. 15 shows a feed line, an intake port,
Another operation example in which a thermoelectric element (heating means) mounted on an exhaust pipe or the like is operated will be shown.

For example, since the temperature of the exhaust pipe, the feed line, and the intake port is low at the time of starting, power is supplied to the thermoelectric element until a certain time has elapsed from the time of starting.

On the other hand, since the temperature of the fuel return line rises during traveling, it may be controlled so that cooling is started after a certain time has elapsed during traveling. In this way, power saving can also be achieved by controlling the input power to the thermoelectric element for time.

[0046]

According to the present invention, HC in exhaust gas and HC evaporating and leaking from the fuel system can be effectively reduced, and moreover, it is a power-saving type and can be easily mounted corresponding to any engine. A device can be provided.

[Brief description of drawings]

FIG. 1 is a basic system configuration diagram of the present invention.

FIG. 2 is a front sectional view of an embodiment in which a flat thermoelectric element is attached to a feed line.

FIG. 3 is a cross-sectional view of FIG. 2 seen from the side.

FIG. 4 is a front sectional view of an embodiment in which an annular thermoelectric element is attached to a feed line.

5 is a cross-sectional view of FIG. 4 seen from the side.

FIG. 6 is a sectional view of an embodiment in which a thermoelectric element is attached to an intake port.

FIG. 7 is a sectional view of an embodiment in which a thermoelectric element is attached to an exhaust pipe.

FIG. 8 is a sectional view of an embodiment in which a thermoelectric element is attached to the return line.

9 is a sectional view of FIG. 8 as seen from the side.

FIG. 10 is a sectional view of an embodiment in which a thermoelectric element is attached to a canister.

FIG. 11 is a sectional view of an example in which a thermoelectric element is mounted between a feed line and a return line.

FIG. 12 is a sectional view of FIG. 11 seen from the side.

FIG. 13 is an explanatory diagram showing an example of a thermoelectric element control circuit using a temperature sensor.

FIG. 14 is an explanatory diagram showing a method for operating a thermoelectric element control system based on a signal from a temperature sensor.

FIG. 15 is an explanatory diagram showing a method of operating the thermoelectric element control system based on set time.

FIG. 16 is an explanatory diagram showing the operating principle of the thermoelectric element.

[Explanation of symbols]

1 ... Engine, 2 ... Intake pipe, 6 ... Intake port, 7 ... Fuel injection valve, 8 ... Feed line system piping, 9 ... Fuel tank,
12 ... Return line system piping, 14 ... Canister, 15
... Exhaust pipe, 17 ... Thermoelectric element (cooling means), 18 ... Thermoelectric element (heating means), 27 ... Thermoelectric element (cooling / heating means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masafumi Oda 7-2 Omika-cho, Hitachi-shi, Ibaraki Energy Research Laboratory, Hitachi, Ltd. (72) Yutaka Takahisa 2520 Takaba, Katsuta-shi, Ibaraki Prefecture Address: Hitachi, Ltd., Automotive Equipment Division

Claims (7)

[Claims] 1. In a fuel supply system of an engine, a thermoelectric element (Peltier element) is provided in at least one of a return line piping for returning fuel from a fuel tank to the fuel tank and a canister for adsorbing fuel evaporated in the fuel tank. )
An HC reducing apparatus for an engine, characterized in that it is provided with a cooling means constituted by. 2. A heating means constituted by a thermoelectric element (Peltier element) is provided in at least one of a pipe of a feed line for supplying fuel from a fuel tank to a engine by a pump and an exhaust pipe of the engine. HC reduction device for engine. 3. A fuel supply system for an engine, comprising: a feed line for supplying fuel to the engine from a fuel tank by a pump; and a return line for returning a part of the fuel in the feed line to the fuel tank again. Line pipes are arranged adjacent to each other with a thermoelectric element (Peltier element) interposed between these pipes, and the heat absorbing surface of the thermoelectric element generated when a current flows is closely attached to the return line pipe and the heat generating surface is An HC reducing apparatus for an engine, comprising a cooling means for the return line and the feed line which are in close contact with a pipe of the feed line. 4. The HC reducing apparatus for an engine according to claim 1, wherein the thermoelectric element is provided with a radiation fin. 5. The temperature sensor for detecting a temperature state of an object to be cooled or an object to be heated of the thermoelectric element according to claim 1, and an output of the temperature sensor is a predetermined value or more. Alternatively, an HC reducing apparatus for an engine, comprising means for controlling energization of the thermoelectric element in the following cases. 6. The control circuit with a timer according to claim 1, further comprising a control circuit with a timer for controlling energization of a thermoelectric element for cooling at least one of the return line and the canister after a lapse of a predetermined time from engine start. HC reduction device for the engine. 7. The control circuit according to claim 2, further comprising a timer-equipped control circuit for controlling energization of a thermoelectric element for heating at least one of the feed line and the exhaust pipe until a predetermined time elapses from engine start. Engine HC reduction device.