Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
1999-02-26
2001-05-08
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C123S550000
Reexamination Certificate
active
06227181
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an internal combustion engine having a combustion heater.
2. Description of the Prior Art
At a cold time, it is required that a warm-up of an internal combustion engine be speeded up, and it is desirable to have a high performance of a car room heater of a vehicle mounted with the internal combustion engine.
For achieving such object, for example, Japanese Patent Application Laid-Open Publication No.62-75069, discloses an art of speeding up the warm-up and enhancing the performance of the car room heater, by providing an intake system with a combustion heater separately from the internal combustion engine body, introducing into the intake system a combustion gas emitted from the combustion heater (which gas is hereinafter referred to as “the combustion gas” unless otherwise specified), raising a temperature of engine cooling water contained in the internal combustion engine body by utilizing combustion heat of the combustion heater and thereby attaining the above object.
On the other hand, as well known, an EGR device primarily aims at reducing a generation of NOx, and secondary aims at enhancing the performance of the car room heater as well as speeding up the warm-up. The letters “EGR” of the EGR device are an abbreviation of Exhaust Gas Recirculation, and the term EGR literally means that a part of the exhaust gas from the internal combustion engine is returned to the intake system from an exhaust system and reintroduced into cylinders. Therefore, the EGR device includes at least an exhaust gas recirculation passageway, which is a pipe for connecting in bypass a discharge passageway and an intake passageway of the internal combustion engine to cylinders thereof, for recirculating the exhaust gas between the discharge passageway and the intake passageway by flowing a part of the exhaust gas back to the intake passageway from the discharge passageway, and an exhaust gas recirculation quantity control valve, disposed in the exhaust gas recirculation passageway, for controlling a quantity of the exhaust gas returned to the intake passageway.
When the EGR device is combined with the internal combustion engine having the combustion heater which introduces the combustion gas into the intake system, the intake system is supplied with both of the combustion gas of the combustion heater and a part (an EGR gas) of the exhaust gas of the internal combustion engine which is recirculated by the EGR device. Each of the combustion gas and the EGR gas is the exhaust gas after being once used. Accordingly, the reuse of such exhaust gas implies that a fresh air quantity to an intake air quantity of the internal combustion engine decreases, while a quantity of carbon dioxide increases. Consequently, there is a possibility that the air/fuel ratio in the cylinders of the internal combustion engine becomes rich enough to produce the smoke.
Further, a concentration of the carbon dioxide contained in the exhaust gas of the combustion heater differs from a concentration of the carbon dioxide contained in the EGR gas of the EGR device. Hence, if mixed, an intake air composed of a mixture of those gases, each having the different concentration of the carbon dioxide, and the fresh air to be used as the intake air of the intake passageway, is used without any adjustment as the intake air of the internal combustion engine, an adverse effect might be exerted upon the combustion in the internal combustion engine. In this case, it is difficult to attain reductions of both NOx and minute powders which are so-called particulate matters (hereinafter referred to as a “PM reduction”) contained in the smoke.
Thus, it is desired to provide an art which is capable of reducing NOx and the smokes, especially, the PM, simply and easily.
SUMMARY OF THE INVENTION
It is a primary object of the present invention, which was devised under such circumstances, to provide an internal combustion engine having a combustion heater capable of easily preventing an air/fuel ratio from becoming rich and reducing NOx and smoke, especially, PM (particulate matter) even when an EGR device is combined with the internal combustion engine having the combustion heater of a type of introducing a combustion gas into an intake system.
To accomplish the above object, according to a first aspect of the present invention, there is provided an internal combustion engine having a combustion heater disposed in an intake system, for speeding up warm-up of the internal combustion engine and enhancing a performance of a car room heater provided in a vehicle mounted with the internal combustion engine, by introducing a combustion gas emitted from the combustion heater to an intake passageway and warming the engine related elements with the combustion heat held by the combustion gas. The internal combustion engine has an exhaust gas recirculation passageway for connecting in bypass an intake passageway and a discharge passageway to cylinders of the internal combustion engine, and comprises an EGR device for recirculating the exhaust gas between the discharge passageway and the intake passageway by returning the exhaust gas of the internal combustion engine to the intake passageway from the discharge passageway through the exhaust gas recirculation passageway, and a recirculated exhaust gas quantity control device for controlling a quantity of the exhaust gas recirculated by the EGR device in accordance with an introduction quantity of the combustion gas into the intake passageway.
Herein, “the engine related elements” are, for example, engine cooling water, and the internal combustion engine itself into which the combustion gas of the combustion heater is introduced as intake air.
“The EGR device” includes at least the exhaust gas recirculation passageway, and an exhaust gas recirculated quantity control valve for controlling a quantity of the exhaust gas returning to the intake passageway from the discharge passageway via the exhaust gas recirculation passageway.
A definition of “controlling the quantity of the exhaust gas recirculated by the EGR device according to the introduction quantity of the combustion gas into the intake passageway”, means “controlling the EGR gas quantity so that a quantity of the mixed gas composed of a mixture of the recirculated exhaust gas and the combustion gas of the combustion heater becomes a certain specified desired quantity”.
Note that hereinafter the recirculated exhaust gas is referred to as the EGR gas unless otherwise specified. Further, the quantity of the mixed gas of the EGR gas and the combustion gas is called a mixed gas quantity. Moreover, “the certain specified desired quantity” relative to the mixed gas quantity is referred to as a target mixed gas quantity. This target mixed gas quantity is not a quantity univocally determined but has an allowance to some extent.
The mixed gas is a gas reusing the exhaust gas of the combustion heater and the EGR gas and containing a comparatively large amount of carbon dioxide. Even in the case of the gas thus containing the comparatively large amount of carbon dioxide, a mixed gas is obtained by mixing it with the fresh air in a state where the mixed gas quantity reaches the target mixed gas quantity, and, if this mixed gas is utilized as the intake air into the internal combustion engine, the combustion in the internal combustion engine is satisfactorily conducted. Further, it can be expected that the warm-up of the internal combustion engine is speeded up with an increased heat quantity received by the cooling water, and besides that a performance of the car room heater of a vehicle mounted with the internal combustion engine is enhanced. These have been proved by the tests performed by the inventor of the present invention. Hence, the target mixed gas quantity is defined as “a mixed gas quantity with which the combustion in the internal combustion engine is satisfactorily conducted, the warm-up of the engine is speeded up, and an enhancement of the performance of the car room heat
Kenyon & Kenyon
Toyota Jidosha & Kabushiki Kaisha
Wolfe Willis R.
LandOfFree
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