JP5709452B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine mounted mainly in an automobile or the like.

  2. Description of the Related Art Conventionally, an engine mounted on an automobile is known that includes an exhaust gas recirculation mechanism that mixes a part of exhaust gas with intake air in order to improve exhaust gas quality and fuel consumption. The exhaust gas recirculation mechanism basically includes, for example, an exhaust gas recirculation passage for recirculating a part of the exhaust gas to the intake passage, and a flow rate control valve provided in the exhaust gas recirculation passage. .

  For example, Japanese Patent Application Laid-Open No. H10-228667 discloses such an exhaust gas recirculation mechanism. The thing of this patent document 1 is that the deposit accumulates on the exit side of the exhaust gas recirculation passage due to a defect in the exhaust gas recirculation mechanism, that is, moisture fine particles such as moisture and carbon in the exhaust gas to be recirculated. In order to solve this problem, the blow-by gas is used. More specifically, in Patent Document 1, a blow-by gas outlet is provided in the vicinity of the outlet to the intake passage of the exhaust gas recirculation passage, and blow-by gas is jetted in the same direction as the recirculated exhaust flow. A blow-by gas control valve is provided in the vicinity of the ejection port.

  By the way, for example, in a two-cylinder engine, particularly an engine that performs combustion at equal intervals at 360 ° CA (crank angle) intervals, if an exhaust gas recirculation mechanism is employed, exhaust pulsation is large, and therefore the flow rate of exhaust gas to be recirculated. May not be stable.

Japanese Utility Model Publication No. 60-34764

  Accordingly, the present invention focuses on the above points and aims to stabilize the flow rate of exhaust gas that is recirculated in an internal combustion engine having a large exhaust pulsation.

That is, the internal combustion engine of the present invention performs equal-interval combustion at 360 ° CA intervals in two cylinders, and recirculates part of the exhaust gas from the upstream side of the catalyst provided in the exhaust passage to the intake passage. A circulation passage, a flow rate control valve provided in the exhaust gas recirculation passage for controlling the amount of exhaust gas to be recirculated, and a blowby for sending blowby gas in the crankcase upstream from the flow control valve in the exhaust gas recirculation passage from the crankcase It is provided with a gas passage and a one-way valve or an electromagnetic PCV valve provided in the blow-by gas passage and allowing the blow-by gas to pass only from the crankcase to the exhaust gas recirculation passage.

  According to such a configuration, the blow-by gas is introduced from the blow-by gas passage to the upstream of the flow rate control valve in a stroke other than the exhaust stroke, so that the pulsation of the exhaust gas recirculated for each combustion is reduced. As a result, the recirculated exhaust gas is stably supplied including the blow-by gas, the combustion is stable, the operating range to which the exhaust gas recirculation control is applied can be expanded, and the fuel efficiency is improved. Is possible.

  The present invention is configured as described above, and the pulsation of the recirculated exhaust gas is mitigated by the introduction of blow-by gas so that the exhaust gas can be stably recirculated, and the exhaust gas recirculation control is applied. Fuel consumption can be improved by expanding the driving range to be performed.

The figure which shows schematic structure of embodiment of this invention. Action | operation explanatory drawing of the same embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  The engine 1 of this embodiment is a two-cylinder engine that performs equal-interval combustion at 360 ° CA intervals. The engine 1 includes a main body 2, an exhaust gas recirculation mechanism (hereinafter referred to as an EGR mechanism) 3, and a blow-by gas passage 4 that are well known in this field. The main body 2 includes each cylinder 5 and a crankcase 6 disposed on the lower side of each cylinder 5. Since the combustion is equally spaced at 360 ° CA intervals, when the first cylinder is in the expansion stroke, the second cylinder is in the intake stroke, and the pistons of both cylinders are lowered at the same time. When the cylinder is in the exhaust stroke, the second cylinder is in the compression stroke, and in this case, the pistons of both cylinders rise simultaneously.

  Each cylinder is provided with two intake valves 7 and two exhaust valves 8. An intake manifold 9 constituting an intake passage is connected to an intake port opened and closed by each intake valve 7. The intake manifold 9 is connected to the surge tank 11 after the pipe lines connected to the respective intake ports in one cylinder are gathered in the intake port collecting portion 10, and flows into the surge tank 11 through the throttle valve 12. Distribute fresh air to each cylinder. The intake manifold 9 of this embodiment has a structure in which the intake port aggregate portions 10 are coupled by the surge tank 11, but the intake port aggregate portions 10 are coupled to each other before being coupled to the surge tank 11 ( A structure in which the pipes connected to the respective intake ports are once coupled at one place and then connected to the surge tank 11 may be employed.

  Similarly, an exhaust manifold 13 constituting an exhaust passage is connected to an exhaust port opened and closed by each exhaust valve 8. The exhaust manifold 13 guides the exhaust gas discharged from each cylinder to the collecting portion 14 and introduces it into the three-way catalyst 15 connected to the collecting portion. An exhaust side end portion 16 a of an exhaust gas recirculation passage (hereinafter referred to as an EGR passage) 16 constituting the EGR mechanism 3 is connected to the collecting portion 14, that is, upstream of the three-way catalyst 15.

  The EGR mechanism 3 includes an EGR passage 16 that recirculates a part of the exhaust gas from the upstream of the three-way catalyst 15 to the intake manifold 9, and a flow rate control valve that is provided in the EGR passage 16 and controls the amount of exhaust gas that is recirculated (hereinafter referred to as the EGR passage 16 , Referred to as an EGR valve) 17. The EGR passage 16 has an intake side end portion 16b opposite to the exhaust side end portion 16a connected to each intake port assembly portion 10 of the intake manifold 9 and thus downstream of the throttle valve 12. The opening and closing of the EGR valve 17 is controlled by an electronic control device (not shown) that controls the operation of the engine in accordance with the operating state of the engine.

  The blow-by gas passage 4 sends out blow-by gas, which is present in the crank case 6 upstream of the EGR valve 17 in the EGR passage 16 from the crank case 6 and is made of lubricating oil vapor, unburned mixture, etc. Is connected to the crankcase 6 and the other end is connected upstream of the EGR valve 17 in the EGR passage 16. The blow-by gas passage 4 is provided with a one-way valve 18 that allows the blow-by gas in the crankcase 6 to pass only in the direction of the EGR passage 16. Therefore, the exhaust gas does not flow into the crankcase 6 from the EGR passage 16 through the blow-by gas passage 4.

In such a configuration, the exhaust gas recirculation control (hereinafter referred to as EGR control) is performed by opening the EGR valve 17 and mixing a part of the exhaust gas (hereinafter referred to as EGR gas) with the intake air. In this case, when one of the two cylinders, for example, the first cylinder is in the exhaust stroke, as shown by a thin solid line in FIG. 2 , the piston rises and the exhaust gas in the cylinder is discharged to the exhaust manifold 13 to cause EGR. The amount of EGR gas in the upstream portion of the EGR valve 17 in the passage 16 increases. The continuous change in the amount of EGR gas indicated by the thin solid line indicates a change in the EGR gas alone, that is, a change when the blow-by gas passage 4 is not functioned.

  At this time, since the piston is rising, blow-by gas existing in the crankcase 6 including the space below the piston, in other words, the space on the opposite side of the combustion chamber across the piston is positively applied to the blow-by gas passage 4. However, it is not pushed out and flows out due to the difference between the pressure in the EGR passage 16 and the pressure in the crankcase 6. Further, since the one-way valve 18 is provided in the blow-by gas passage 4, the EGR gas does not move from the EGR passage 16 toward the crankcase 6. Therefore, the amount of EGR gas that passes through the EGR valve 17 and flows into the intake manifold 9 increases as the exhaust stroke proceeds.

Thereafter, when the first cylinder is in the intake stroke, the exhaust valve 8 of the first cylinder is closed and the intake valve 7 is opened, so that the amount of EGR gas in the above-described portion gradually decreases. At this time, since the pistons of both cylinders descend simultaneously, the blow-by gas existing on the lower side of the piston, in other words, on the opposite side of the combustion chamber with the piston sandwiched, as shown by the dotted line in FIG. As it progresses, it is pushed out from the crankcase into the blow-by gas passage 4 to increase its amount. The continuous change in the blow-by gas amount indicated by the dotted line indicates a change in the blow-by gas alone, that is, a change not taking into account the EGR gas amount.

As a result, the blow-by gas is mixed with the decreasing EGR gas in the upstream portion of the EGR valve 17 in the blow-by gas passage 4 and the EGR passage 16, and the decrease in the EGR gas amount is alleviated as a whole. For this reason, the amount of EGR gas that flows in the intake manifold 9 in the EGR passage downstream from the EGR valve 17 has a smaller change width than the change in the EGR gas alone, as shown by the thick solid line in FIG. That is, the pulsation is flattened and the fluctuation is small.

  Thus, in the process of reducing the amount of only EGR gas, since the blow-by gas is mixed with the EGR gas, it is possible to suppress a decrease in the actual amount of EGR gas mixed with the intake air. At the same time, blow-by gas can be consumed efficiently, and ventilation in the crankcase 6 can be promoted. For this reason, since there is little fluctuation | variation (pulsation) of EGR gas amount, EGR gas can be supplied stably and combustion can be stabilized between cycles. By stabilizing the combustion in this way, it is possible to promote improvement in fuel consumption.

  The present invention is not limited to the above embodiment.

  For example, instead of the one-way valve 18 provided in the blow-by gas passage 4, an electromagnetic control valve (PCV valve) may be used. When using an electromagnetic control valve, the opening degree of the electromagnetic control valve is reduced in the intake stroke and the expansion stroke, the amount of blow-by gas flowing out from the crankcase 6 to the EGR passage 16 is limited, and the opening degree is increased in the compression stroke. By doing so, the opening degree of the electromagnetic control valve is controlled so as to increase the amount of blow-by gas flowing out from the crankcase 6 to the EGR passage 16 during the compression stroke. Thus, by controlling the opening degree of the electromagnetic control valve according to the stroke, the pulsation of the EGR gas amount including the blow-by gas mixed into the intake air is flattened as in the above embodiment. .

  In the case of an engine equipped with a supercharger, the end of the EGR passage on the exhaust system side is connected to the downstream of the three-way catalyst downstream of the turbine, and the end of the intake system is connected to the compressor. It may be connected upstream.

  The main body of the engine may be a single cylinder.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  As an application example of the present invention, there is an internal combustion engine with a small number of cylinders that performs EGR control, in which pulsation occurs in the amount of EGR gas.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Main body 3 ... Exhaust gas recirculation passage 4 ... Blow-by gas passage 6 ... Crank case 17 ... Flow control valve 18 ... One-way valve

Claims (1)

An exhaust gas recirculation passage that recirculates a portion of the exhaust gas from the catalyst upstream provided in the exhaust passage to the intake passage;
A flow rate control valve for controlling the amount of exhaust gas to be recirculated provided in the exhaust gas recirculation passage;
A blowby gas passage for sending blowby gas in the crankcase upstream from the flow control valve of the exhaust gas recirculation passage from the crankcase;
An internal combustion engine that is provided in a blow-by gas passage and has a one-way valve or an electromagnetic PCV valve that allows blow-by gas to pass only from a crankcase to an exhaust gas recirculation passage, and performs equal combustion at 360 ° CA intervals in two cylinders .

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