JP2018115606A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of preventing an air fuel ratio from becoming rich because purge gas staying on the upper stream side than a throttle valve is introduced to a combustion chamber, upon deceleration.SOLUTION: In an internal combustion engine, a changeover valve 370 of a vaporization fuel purge system 300 is attached to a part of the upper stream side than a compressor 220 on a suction pipe 120 in such a state that a through-hole provided on the part of the upper stream side than the compressor and a first port 371 are communicated. Therein, a canister 450 and a second port 372 are connected with an upper stream side purge piping 340, and a part of the lower side than the throttle valve 150 on the suction pipe 120 and a third port 373 are connected with a lower stream side purge piping 380.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an on-vehicle internal combustion engine with a supercharger and to an internal combustion engine equipped with an evaporated fuel purge system.

  The vehicle is provided with a canister that collects the evaporated fuel generated in the fuel tank. For vehicles equipped with a canister, air is introduced into the canister from the outside, and the collected fuel is purged together with air into the intake passage of the operating internal combustion engine as a purge gas to recover the collecting performance of the canister An evaporative fuel purge system is also installed.

  In the case of an internal combustion engine with a supercharger, purge can be performed by sucking purge gas from the canister side using negative pressure downstream of the throttle valve in the intake passage when supercharging is not being performed. At the time of supply, since the downstream side of the throttle valve in the intake passage becomes a positive pressure, purging cannot be performed. Therefore, there is also an evaporated fuel purge system in which purge is performed by introducing purge gas from the canister side upstream of the compressor in the intake passage during supercharging.

  As such an evaporative fuel purge system, Patent Document 1 discloses a first purge passage connected to the downstream side of the throttle valve in the intake passage, a second purge passage connected to the upstream side of the compressor in the intake passage, and a canister. An evaporative fuel purge system in which a connected upstream purge passage is connected via a switching valve is disclosed.

  In such an evaporative fuel purge system, purging is performed via the second purge passage when supercharging is performed, and purging is performed via the first purge passage when supercharging is not performed.

JP 2006-104986 A

  By the way, when the vehicle is changed from the supercharged state to the decelerated state, such as when the vehicle is changed from the accelerated state to the decelerated state, the second purge passage is closed by the switching valve. The purge gas stays in the portion from the portion where the second purge passage is connected to the throttle valve and in the second purge passage. It is preferable from the viewpoint of emission control that the purge gas staying upstream from the throttle valve is introduced into the combustion chamber at the time of deceleration where the intake air amount is limited by the throttle valve and the air-fuel ratio becomes rich. Absent.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
An internal combustion engine for solving the above problems includes a supercharger, a canister that collects evaporated fuel generated in a fuel tank, and an evaporated fuel purge system that introduces the evaporated fuel collected in the canister into an intake pipe. It has. The evaporative fuel purge system includes a switching valve in which a valve body that switches between communication and blocking of each port is housed in a housing in which a first port, a second port, and a third port are formed. In this internal combustion engine, the switching valve is attached to a portion of the intake pipe upstream of the compressor of the supercharger in a state where a through hole provided in the portion and the first port communicate with each other. The canister and the second port are connected by an upstream purge pipe, and a portion downstream of the throttle valve in the intake pipe and the third port are connected by a downstream purge pipe.

  In the above configuration, the first port is directly connected to the upstream side of the compressor in the intake pipe without passing through the purge pipe. Therefore, the volume of the passage from the first port of the switching valve to the intake pipe can be reduced as compared with the case where the first port is connected via the purge pipe. Therefore, according to the above configuration, when the vehicle shifts from the acceleration state to the deceleration state and shifts from the supercharged state to the deceleration state, the amount of purge gas that stays upstream from the throttle valve is reduced. can do.

  That is, according to the above configuration, at the time of deceleration in which the intake air amount is limited by the throttle valve, purge gas staying upstream from the throttle valve is introduced into the combustion chamber, and the air-fuel ratio becomes rich. As a result, the deterioration of the emission due to the rich air-fuel ratio can be suppressed.

1 is a schematic diagram showing a schematic configuration of an evaporated fuel purge system mounted on the internal combustion engine according to an embodiment of the internal combustion engine. FIG. The schematic diagram which shows the state which the switching valve of the same fuel vapor purge system has made the 3rd port and the 2nd port communicate. The schematic diagram which shows the state which the switching valve of the same fuel vapor purge system has made the 2nd port and the 1st port communicate.

Hereinafter, an embodiment of an internal combustion engine will be described with reference to FIGS. This internal combustion engine is an internal combustion engine mounted on a vehicle.
As shown in FIG. 1, four combustion chambers 110 are provided in an engine body 100 including a cylinder block and a cylinder head in an internal combustion engine. An intake pipe 120 and an exhaust pipe 130 are connected to the engine body 100. The intake pipe 120 has a downstream end branched into four, and each combustion chamber 110 provided in the engine main body 100 communicates with the branched end one by one in the engine main body 100. It is connected. Further, the exhaust pipe 130 has an upstream end branched into four, and like the intake pipe 120, each combustion chamber 110 provided in the engine body 100 and this branched end are one by one. The engine body 100 is connected so as to communicate with each other.

  This internal combustion engine includes a turbocharger 200 as a supercharger. Therefore, the turbine 210 of the turbocharger 200 is arranged in the middle of the exhaust pipe 130, and the compressor 220 of the turbocharger 200 is arranged in the middle of the intake pipe 120. A turbine wheel 211 is accommodated in the turbine 210, and a compressor wheel 221 connected to the turbine wheel 211 via a rotating shaft is accommodated in the compressor 220. Thereby, the energy of the exhaust gas flowing through the exhaust pipe 130 is recovered by the turbine 210, and the compressor 220 can be supercharged by the energy. The exhaust pipe 130 is connected to a portion upstream of the turbine 210 and a portion downstream from the turbine 210. The bypass passage 240 bypasses the turbine 210 and allows the exhaust to flow, and the bypass passage 240 is opened and closed. A wastegate valve 250 is provided. Thus, the supercharging by the turbocharger 200 can be suppressed by opening the waste gate valve 250 and allowing the exhaust gas to flow through the bypass passage 240.

  An intercooler 140 for cooling the intake air is provided in a portion of the intake pipe 120 on the downstream side of the compressor 220. A surge tank 160 that reduces pulsation of intake air is provided in a portion of the intake pipe 120 downstream of the intercooler 140. The intake pipe 120 branches at a portion downstream of the surge tank 160 and is connected to the engine body 100. A throttle valve 150 that adjusts the amount of intake air is provided in a portion of the intake pipe 120 between the surge tank 160 and the intercooler 140.

  The internal combustion engine also includes a canister 450 that collects the evaporated fuel generated in the fuel tank 400. The canister 450 and the fuel tank 400 are connected via an evaporative fuel pipe 410. Activated carbon is stored in the canister 450, and when evaporated fuel generated in the fuel tank 400 is introduced into the canister 450 through the evaporated fuel pipe 410, the evaporated fuel is adsorbed on the activated carbon and collected in the canister 450. It has become.

  Further, the internal combustion engine is purged by introducing air into the canister 450 from outside and introducing the collected fuel into the intake pipe 120 of the operating internal combustion engine as a purge gas together with the air. An evaporative fuel purge system 300 for recovery is also mounted.

  The evaporated fuel purge system 300 can introduce a purge gas into a portion of the intake pipe 120 upstream of the compressor 220 or introduce a purge gas into a portion downstream of the throttle valve 150 depending on the situation. It is configured as follows.

  Specifically, a switching valve 370 for switching the purge gas introduction destination is provided, and this switching valve 370 is attached to a portion of the intake pipe 120 upstream of the compressor 220. The switching valve 370 houses a valve body 376 that switches between communication and blocking of the ports 371, 372, and 373 inside a housing 375 in which the first port 371, the second port 372, and the third port 373 are formed. Is.

  As shown in FIG. 1, the valve body 376 is formed with an intra-valve passageway. By rotating the valve body 376 within the housing 375, the ports 371, 372, and 373 can be connected and disconnected. Can be switched. The valve body is driven by a motor, and the direction of the valve body 376 can be controlled by controlling the motor.

  A through hole is formed in the portion of the intake pipe 120 where the switching valve 370 is attached, and the switching valve 370 communicates with the first port 371 and the through hole provided in the intake pipe 120. , Attached to the intake pipe 120. The second port 372 of the switching valve 370 is connected to the canister 450 by the upstream purge pipe 340, and the third port 373 is connected to the portion of the intake pipe 120 downstream of the throttle valve 150 by the downstream purge pipe 380. It is connected.

  A purge control valve 360 that closes the upstream purge pipe 340 when the valve is closed is provided in the middle of the upstream purge pipe 340. In addition, a purge pump 350 that sucks purge gas from the canister 450 side and sends it to the switching valve 370 side is provided at a portion upstream of the purge control valve 360 in the upstream side purge pipe 340.

  Control of each part of the internal combustion engine including control of the direction of the valve body 376 in the switching valve 370 is performed by the control device 500. The control device 500 includes an accelerator position sensor 510 that detects the amount of operation of the accelerator, a vehicle speed sensor 520 that detects the vehicle speed that is the speed of the vehicle, and a crank position sensor that detects the rotation angle of the crankshaft that is the output shaft of the internal combustion engine. 530 is connected. In addition, the control device 500 controls the air flow meter 540 that detects the intake air amount that is the amount of air sucked into the combustion chamber 110 through the intake pipe 120, and the pressure in the downstream portion of the intake pipe 120 from the compressor 220. A supercharging pressure sensor 550 to be detected is also connected.

  The control device 500 controls the internal combustion engine based on information detected by these sensors. Specifically, based on the vehicle speed detected by the vehicle speed sensor 520 and the accelerator operation amount detected by the accelerator position sensor 510, the magnitude of the required torque is estimated and necessary for generating the estimated torque. The opening degree of the throttle valve 150 is adjusted to realize the intake air amount. Then, the injector 560 is controlled so as to supply an amount of fuel corresponding to the amount of intake air. In this internal combustion engine, one in-cylinder injector 560 that supplies fuel directly to the combustion chamber 110 of the internal combustion engine is provided for each combustion chamber 110. Further, the control device 500 controls the ignition timing in each combustion chamber 110 by controlling the spark plugs 570 provided one by one in each combustion chamber 110 in order to realize the required torque.

  The control device 500 also controls supercharging by the turbocharger 200 by opening and closing the waste gate valve 250 in accordance with the control of the throttle valve 150, the injector 560, and the spark plug 570 as described above. That is, when the required torque is large, the waste gate valve 250 is closed and the turbocharger 200 performs supercharging. On the other hand, when the required torque is small, the waste gate valve 250 is opened so that the exhaust gas flows around the turbine 210 to suppress supercharging.

Further, the control device 500 also controls the evaporated fuel purge system 300.
Specifically, as shown in FIG. 1, when the purge execution condition is not satisfied, the switching valve 370 is controlled so that the valve passage in the valve element 376 is one of the ports 371, 372, and 373. In addition, the purge control valve 360 is closed and the upstream purge pipe 340 is closed to prevent purging.

  On the other hand, when the internal combustion engine is in operation and the purge execution condition is satisfied, the purge control valve 360 is opened, the purge pump 350 is driven, and the purge gas is supplied to the intake pipe 120 side through the upstream purge pipe 340. To send. At this time, the switching valve 370 is controlled depending on whether the pressure detected by the supercharging pressure sensor 550 is high or low, and purge gas is introduced into a portion of the intake pipe 120 downstream of the throttle valve 150, or the intake pipe 120 It determines whether to introduce into the part upstream from the compressor 220 in.

  As shown in FIG. 2, when the pressure detected by the supercharging pressure sensor 550 is low and the turbocharger 200 is not supercharging, the control device 500 controls the valve body 376 of the switching valve 370. The second port 372 and the third port 373 are controlled to communicate with each other. That is, when it is estimated that the pressure at the downstream side of the throttle valve 150 in the intake pipe 120 is a negative pressure lower than the atmospheric pressure, the valve body 376 of the switching valve 370 is connected to the second port 372 and the second port 372. The direction of communication with the 3 port 373 is controlled. Thus, the purge gas introduced into the second port of the switching valve 370 through the upstream purge pipe 340 is downstream of the throttle valve 150 in the intake pipe 120 through the downstream purge pipe 380 connected to the third port 373. To be introduced into the part. The purge gas thus introduced into the intake pipe 120 is introduced into the combustion chamber 110 together with the intake air flowing through the intake pipe 120 and used for combustion in the combustion chamber 110.

  Further, as shown in FIG. 3, when the pressure detected by the supercharging pressure sensor 550 is high and the turbocharger 200 is performing supercharging, the control device 500 controls the valve body of the switching valve 370. 376 is controlled in a direction in which the second port 372 and the first port 371 communicate with each other. That is, when it is estimated that the pressure in the portion downstream of the throttle valve 150 in the intake pipe 120 is a positive pressure higher than the atmospheric pressure, the valve body 376 of the switching valve 370 is connected to the second port 372 and the second port 372. It controls to the direction which makes 1 port 371 communicate. Accordingly, the purge gas introduced into the second port of the switching valve 370 through the upstream purge pipe 340 is introduced into a portion of the intake pipe 120 upstream of the compressor 220 through the first port 371. The purge gas thus introduced into the intake pipe 120 is also introduced into the combustion chamber 110 together with the intake air flowing through the intake pipe 120 and used for combustion in the combustion chamber 110.

  Purging is performed in this manner, and the evaporated fuel adsorbed on the activated carbon accommodated in the canister 450 is introduced into the intake pipe 120 and processed by combustion in the combustion chamber 110, so that the evaporative fuel can be collected in the canister 450. Recover. The control device 500 performs the purge when the internal combustion engine is operated and the purge execution condition is satisfied, and recovers the evaporated fuel collecting ability in the canister 450 as needed.

Next, the effect | action of the internal combustion engine concerning this embodiment and the effect acquired by the effect | action are demonstrated.
When the vehicle is accelerating and the turbocharger 200 is supercharged, the pressure in the portion of the intake pipe 120 downstream of the throttle valve 150 is a positive pressure higher than the atmospheric pressure. As shown, the purge gas is introduced into the intake pipe 120 through the first port 371.

  When the vehicle is shifted from the state of supercharging by the turbocharger 200 to the deceleration state, such as when the vehicle is shifted from the acceleration state to the deceleration state, as shown in FIG. The first port 371 is closed by 370, and the purge is stopped. Alternatively, depending on the degree of deceleration, as shown in FIG. 2, the first port 371 is closed by the switching valve 370, and the second port 372 and the third port 373 are in communication with each other. In these cases, although the purge through the first port 371 is stopped, the purge gas stays in the portion from the portion where the first port 371 is connected to the throttle valve 150 in the intake pipe 120. It is not preferable from the viewpoint of emission control when purge gas staying in the intake pipe 120 is introduced into the combustion chamber 110 and the air-fuel ratio becomes rich at the time of deceleration where the intake air amount is limited by the throttle valve 150. .

  On the other hand, in the internal combustion engine described above, the first port 371 is directly connected to the upstream side of the compressor 220 in the intake pipe 120 without passing through the purge pipe. Therefore, the volume of the passage from the first port 371 of the switching valve 370 to the intake pipe 120 can be reduced as compared with the case where the first port 371 is connected via the purge pipe. Therefore, the amount of purge gas that stays upstream from the throttle valve 150 when the state of supercharging is changed to the deceleration state can be reduced.

  That is, the purge gas staying upstream of the throttle valve 150 is introduced into the combustion chamber 110 at the time of deceleration while the intake air amount is limited by the throttle valve 150, and the air-fuel ratio is prevented from becoming rich. be able to. As a result, the deterioration of the emission due to the rich air-fuel ratio can be suppressed.

In addition, said embodiment can also be implemented with the following forms which changed this suitably.
The switching valve 370 is not limited to the one valve body 376 that switches the connection state of the ports 371, 372, and 373. One valve body may be provided in each of the ports 371, 372, and 373, and the opening and closing of each valve body may be controlled. Even when such a configuration is employed, the switching valve 370 can switch between communication and blocking of the ports 371, 372, and 373.

  In order to minimize the purge gas staying in the upstream side of the throttle valve 150 in the intake pipe 120 when the acceleration state is shifted to the deceleration state, the switching valve is attached to the compressor 220 in the intake pipe 120. It is preferable that the position is as close as possible.

  ・ The turbocharger is not limited to a turbocharger. For example, even in an internal combustion engine that employs an electric supercharger driven by a motor as a supercharger or a supercharger that operates a compressor 220 using a part of the driving force of the internal combustion engine, The same effect as the embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 100 ... Engine main body, 110 ... Combustion chamber, 120 ... Intake pipe, 130 ... Exhaust pipe, 140 ... Intercooler, 150 ... Throttle valve, 160 ... Surge tank, 200 ... Turbocharger, 210 ... Turbine, 211 ... Turbine wheel, 220 Compressor, 221 ... Compressor wheel, 240 ... Bypass passage, 250 ... Waste gate valve, 300 ... Evaporative fuel purge system, 340 ... Upstream purge pipe, 350 ... Purge pump, 360 ... Purge control valve, 370 ... Switching valve, 371 ... 1st port, 372 ... 2nd port, 373 ... 3rd port, 375 ... Housing, 376 ... Valve body, 380 ... Downstream purge piping, 400 ... Fuel tank, 410 ... Evaporative fuel piping, 450 ... Canister, 500 ... Control device, 510 ... accelerator position Nsensa, 520 ... vehicle speed sensor, 530 ... crank position sensor, 540 ... flow meter, 550 ... boost pressure sensor, 560 ... Injector, 570 ... spark plug.

Claims (1)

An internal combustion engine comprising a supercharger, a canister for collecting evaporated fuel generated in a fuel tank, and an evaporated fuel purge system for introducing the evaporated fuel collected in the canister into an intake pipe,
The evaporative fuel purge system includes a switching valve in which a valve body that switches between communication and blocking of each port is housed in a housing in which a first port, a second port, and a third port are formed.
The switching valve is attached to a portion upstream of the compressor of the supercharger in the intake pipe in a state in which a through hole provided in the portion and the first port are in communication with each other.
An internal combustion engine in which the canister and the second port are connected by an upstream purge pipe, and a portion of the intake pipe that is downstream of the throttle valve and the third port is connected by a downstream purge pipe.

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