JP3161561U - Novel exhaust pipe structure in automobile exhaust system - Google Patents

Abstract

An exhaust pipe structure using a thermoelectric conversion element having heat resistance is provided. Research on thermoelectric conversion elements has progressed, and heat-resistant elements have been developed. A heat-resistant thermoelectric conversion element 9 of 500 ° C. or higher is attached to the exhaust pipe 8 between the catalytic converter and the muffler to convert the exhaust heat into electricity, and the electric energy of the vehicle air conditioner, power window, wiper, lamp, etc. It solves by using as. [Selection] Figure 4

Description

  The present invention relates to a technology for energy saving of an automobile, and relates to a novel exhaust pipe structure to which a thermoelectric conversion element having a heat resistance of 500 ° C. or higher is applied.

  So far, bismuth telluride has been put to practical use as a Peltier element for cooling, but has not been used as an element for converting heat into electricity. This is because there was no element that can withstand high temperatures. Recently, heat-resistant thermoelectric conversion elements have been developed, and exhaust heat thermoelectric conversion has been studied. Thermoelectric conversion elements using a composite oxide sintered body selected from various elements have been announced (Patent Documents 1 and 2). In the announcement titled “Power Generation from Wasted Heat,” oxides of calcium and cobalt and oxides of lanthanum and nickel have been developed as power generation elements (Non-patent Document 1).

  As a clathrate compound, a technique for producing a thermoelectric conversion element using a metal in which barium or gold is incorporated in a germanium crystal has been developed (Patent Document 3).

  Next, the prior art in the automobile field was searched by a publication text search. When searching by automobile, exhaust pipe, and thermoelectric conversion element, two utility models could be searched (Patent Documents 4 and 5). When searching by automobile, exhaust pipe, and thermoelectric conversion module, two patents could be searched (Patent Document 6 and Patent Document 7). Patent Document 4 is a technique in which a heat exchange jacket is placed in an exhaust pipe to effectively transfer heat to an element. On the cooling surface, a water cooling method using cold water is adopted. Lead and tellurium compounds are used as thermoelectric conversion elements. Patent document 5 is an old publication and there is no detailed record, but it is an application regarding an auxiliary cooling device. Patent Documents 4 and 5 have no request for examination and have not been granted rights.

  Patent document 6 is also unclaimed and cannot be obtained. There is no description of the material of the thermoelectric conversion element. Fin cooling is adopted as the structure. In the patent document 7, the composition of the element is disclosed, and the element is composed of an intermetallic compound of magnesium, silver, and arsenic. Moreover, as Example 12, the figure which distribute | circulates high temperature waste gas and cooling water is exhibited by this heat exchanger with a thermoelectric conversion module.

Patent 3089301 Patent 4239010 JP2007-23349 Actual open Hei 06-079168 Japanese Utility Model Sho 63-138218 JP 10-234194 A JP2009-081287A

National Institute of Advanced Industrial Science and Technology, Volume 5, NO. 8 (2005)

  The problem to be solved by the present invention is, first, which heat is used for use in an exhaust system of a gasoline engine. The exhaust manifold hot gas discharged from the cylinder is 950 ° C., and the temperature of the subsequent catalytic converter is close to 950 ° C., but the heat here cannot be taken. Furthermore, although the underfloor catalytic converter is also at a high temperature of 750 ° C., heat cannot be removed in order to sufficiently perform exhaust gas catalytic reaction. Exhaust pipe heat from 750 ° C. to 500 ° C. to the center muffler is available past the underfloor catalytic converter.

  After a considerable temperature drop, it is still exhaust gas at a temperature of several hundred degrees. Therefore, the heat resistance of the thermoelectric conversion element is the next problem. Bismuthellide elements cannot be used. It is necessary to select from a high melting point alloy, metal oxide or the like.

  Further, the next problem is the use of a metal having a so-called Seebeck effect in which an electromotive force is generated when a temperature difference is generated between both ends of a semiconductor in order to convert heat into electricity. The efficiency of converting heat into electricity can be expressed as the power that can be taken out divided by the amount of heat that flows in. Higher efficiency is preferred.

  High heat resistance compound, semiconductor with Seebeck effect, magnesium silicide or silica and germanium alloy for silicide compounds, skutterudite for cobalt antimony, oxide of calcium and cobalt from 300 ° C It was found to be suitable for thermoelectric conversion at 600 ° C.

  When the heat collecting side of the element for thermoelectric conversion is brought into close contact with the surface of the exhaust pipe at 500 ° C. to 600 ° C. and the other surface is cooled, the temperature difference can be realized and the thermoelectric conversion efficiency is high enough to perform cooling. . When the thermoelectric conversion element is not sufficiently adhered to the heat collecting portion, the efficiency is lowered, so that the gap is filled with a material having good thermal conductivity such as silver paste. Furthermore, in order to lower the temperature on the low temperature side, efficiency is increased by attaching metal fins with high thermal conductivity to the periphery and performing air cooling when the vehicle is running.

It is the schematic diagram which showed the exhaust system of the car. It is the expanded sectional view which attached the fin to the thermoelectric element and its peripheral part to piping of a high temperature part. a Schematic diagram with thermoelectric conversion element attached to exhaust pipe with circular cross section b Schematic diagram with thermoelectric conversion element attached to exhaust pipe with square cross section Schematic diagram with a thermoelectric conversion element attached to an exhaust pipe with a square cross section and a cooling plate that allows cooling water to pass through it. Schematic diagram of a thermoelectric conversion component with a thermoelectric conversion element bonded to the surface of the exhaust pipe used between the underfloor catalytic converter and the muffler and fins attached to the external surface

A mode for carrying out the invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an exhaust system of a car.
1 is an exhaust manifold, and 2 is a catalytic converter immediately below.
3 is an underfloor catalytic converter and 5 is a center muffler. 4 and 5 are connecting parts for the underfloor converter and the muffler parts. Reference numeral 7 denotes a main muffler which silences and cools the exhaust and discharges exhaust gas from the exhaust pipe of the car to the atmosphere.

  In this exhaust system, the present invention technique is carried out by replacing the exhaust pipe at 500 ° C. to 600 ° C. between the underfloor catalytic converter and the center muffler with an exhaust pipe having a thermoelectric conversion element as shown in FIG. 8 is a cross section of the exhaust pipe, and the case where the cross section is circular and the case of a square pipe are shown. Reference numeral 9 denotes a pasted thermoelectric conversion element. In order to cool the low temperature side of the thermoelectric conversion element, as shown at 10, plate-like fins are arranged to cool the external surface of the thermoelectric conversion element by air cooling when the vehicle is running.

  In the case of FIG. 2a, it is necessary to join the bottom surface of the element with the same curved surface as the pipe having a curvature. 11 is an adhesive layer to the exhaust pipe, and in order to make it adhere completely and move heat, the unevenness is filled with a silver paste to increase the degree of adhesion. In the case of FIG. 2b, although it is a plane and a plate of an element is stuck side by side, in order to raise the adhesion degree of 11, silver paste is also used.

  While the car is traveling, the wind of the outside air hits the fins and has a cooling effect. When the car is not traveling, there is little temperature difference between the two sides of the thermoelectric conversion element, and the amount of power generation is extremely small. Thermoelectric conversion is performed only when traveling. To cool even when the vehicle is stopped, there is a method of circulating cooling water in the vehicle. As shown in an example in FIG. 3, a water-cooled plate is stacked on a thermoelectric conversion element attached to the exhaust pipe. The water cooling method has a more complicated structure than air cooling.

  The exhaust pipe with a diameter of about 10 cm between the underfloor catalytic converter and the center muffler is remodeled, and the thermoelectric conversion elements 9 are arranged and joined around the exhaust pipe 8 as shown in FIG. Attached. Ten fins were arranged in the peripheral part, and the fins were arranged at intervals such that the wind could blow through them. The connecting part between 4-1 and 4-2 was connected to the underfloor catalytic converter and the center muffler.

  The pipe surface at the inlet of this device with a modified exhaust pipe was 700 ° C., and the outlet temperature was 250 ° C. Heat was supplied to the thermoelectric conversion element so that a temperature difference of 450 ° C. was generated by the fins, and cooling was performed by the fins to form a temperature difference to generate power. The heat energy that was not used passed through the center muffler and was silenced, and the main muffler reached a temperature of 150 ° C. The generated electric power was used as 12V as energy for the electric part in the vehicle, and a part of the electric power was stored in the battery.

  Only about 20% of the combustion heat of gasoline is used to drive the car. 20% of heat is used for tire frictional heat, rotating shaft friction, in-vehicle temperature controller, electric lamp, wiper, etc., and 60% is released into the atmosphere as exhaust gas. If even part of it can be converted into electricity and used in the vehicle, it can contribute to the prevention of global warming.

  Many of the recent cars charge only on the downhill, and use a lot of power in the car, so the battery power is not enough and often causes troubles. In order to prevent this, it is desirable that a part of the exhaust heat can be converted into electricity and used for driving the car.

  When the era of electric vehicles comes, exhaust gas and exhaust pipes will disappear, but about 10 years are still the era of gasoline vehicles. The present invention, which contributes to energy saving of automobiles and reduction of carbon dioxide emissions, may be used for a while in the automobile industry.

DESCRIPTION OF SYMBOLS 1 Exhaust manifold 2 Catalytic converter just under an exhaust manifold 3 Underfloor catalytic converter 4 Connection part of two catalytic converter parts 5 Center muffler 6 Connection part of underfloor catalytic converter and center muffler part 7 Main muffler 8 Exhaust pipe 9 Affixed on the surface of the exhaust pipe Aggregate of thermoelectric conversion elements 10 Arrangement of fins for heat dissipation 11 Adhesive layer 12 for exhaust pipe excellent in heat resistance and thermal conductivity Adhesive layer 13 for thermoelectric conversion elements and fins excellent in heat resistance and thermal conductivity Cooler with water channel for water cooling 4-1 Connection to catalytic converter 4-2 Connection to muffler

Claims (3)

In the exhaust system of a vehicle engine, a thermoelectric conversion selected from magnesium silicide, an alloy of silica and germanium, skutterudite, and oxides of calcium and cobalt in an exhaust pipe having a temperature of 250 ° C. or more from the underfloor catalytic converter to the muffler Exhaust pipe structure of a vehicle with attached elements The exhaust pipe structure according to claim 1, wherein the heat collecting surface of the thermoelectric conversion element is closely adhered to the exhaust pipe of the vehicle engine with a silver paste having good thermal conductivity, and the heat radiation fin is attached to the outer cooling surface. The exhaust of a vehicle according to claim 1, wherein the heat collecting surface of the thermoelectric conversion element is closely attached to the exhaust pipe of the engine of the vehicle with a silver paste having good thermal conductivity, and the outer cooling surface is cooled with cooling water for engine cooling. Tube structure

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