JP2013234590A - Exhaust recirculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust recirculation device whose body size can be downsized.SOLUTION: An ejector 30 forms a squeeze passage 321 through which fresh gas flowing within an intake manifold 131 flows, a suction passage 331 through which recirculation exhaust flows, a first communication path 341 capable of being communicated with a first exhaust recirculation passage 131 connected to an exhaust pipe 130 via an exhaust recirculation control valve 40, a mixing passage 351 and the like. When the fresh gas flows through the squeeze passage 321, the recirculation exhaust of the suction passage 331 is sucked by a negative pressure generated on the downstream side of the squeeze passage 321. When a pressure in the first communication path 341 is turned to be a predetermined pressure or less by the negative pressure, an exhaust recirculation control valve 30 is opened, and a first exhaust recirculation passage 211 is communicated with the first communication path 341. Thereby, the recirculation exhaust of the first exhaust recirculation passage 211 is mixed with the fresh gas in a mixing passage 351 through the suction passage 331. As the result, the recirculation exhaust and the fresh gas can be mixed with a simple structure and a body size can be downsized.

Description

  The present invention relates to an exhaust gas recirculation device that recirculates part of exhaust gas of an internal combustion engine to an intake system.

  Conventionally, an exhaust gas recirculation device that recirculates a part of exhaust gas flowing through an exhaust system of an internal combustion engine to an intake system is known. Patent Document 1 discloses an intake control valve that is provided in an intake system and controls the amount of fresh air supplied to a combustion chamber of an internal combustion engine, and an exhaust gas recirculation that controls the timing at which the exhaust gas in the exhaust gas recirculation passage is recirculated to the intake system. A gas control valve and an opening / closing operation timing control means for controlling the opening / closing timing of the two control valves are provided, and the timing for supplying fresh air and the exhaust gas in the exhaust gas recirculation passage to the combustion chamber according to the operating conditions of the internal combustion engine. An exhaust recirculation gas introduction control device for an internal combustion engine that realizes stratified combustion in a combustion chamber by making it different is described.

JP 2006-266159 A

  However, in the exhaust gas recirculation gas introduction control device described in Patent Document 1, the intake control valve and the exhaust gas recirculation gas control valve need to operate at high speed according to the rotational speed of the internal combustion engine, and the opening / closing operation timing control means is Since it is driven by electricity, the structure becomes complicated. Further, in the case of a multi-cylinder internal combustion engine having a plurality of cylinders, since the intake control valve and the exhaust gas recirculation gas control valve are provided in each cylinder, the size of the apparatus becomes large.

  An object of the present invention is to provide an exhaust gas recirculation device that can be reduced in size.

  The present invention is an exhaust gas recirculation device that mixes a part of exhaust gas flowing through an exhaust system of an internal combustion engine with recirculated exhaust gas into fresh air flowing through an intake system of the internal combustion engine, and forms a first exhaust gas recirculation passage. A pipe, a throttle portion that forms a throttle passage that reduces the cross-sectional area of fresh air flowing from the upstream side to the downstream side of the intake system, a suction passage forming portion that forms a suction passage through which the reflux exhaust flows, and fresh air and reflux exhaust A mixing portion that forms a mixing passage for mixing the first and second ejectors, a ejector having a first communication passage forming portion that forms a first communication passage that communicates with the suction passage, and the first exhaust recirculation passage and the first communication passage. An exhaust gas recirculation control valve provided in a possible manner, and the exhaust gas recirculation control valve communicates the first exhaust gas recirculation passage and the first communication passage when the pressure of the first communication passage is equal to or lower than a predetermined pressure. To do.

  When fresh air passes through the throttle portion of the ejector, negative pressure is generated by the flow of fresh air downstream of the throttle passage. The magnitude of this negative pressure has a certain relationship with the flow rate of fresh air flowing through the throttle. The negative pressure generated on the downstream side of the throttle portion sucks the reflux exhaust in the suction passage toward the mixing passage, and also sucks the reflux exhaust in the first communication passage communicating with the suction passage. At this time, when the pressure in the first communication path is equal to or lower than a predetermined pressure, the exhaust gas recirculation control valve communicates the first exhaust gas recirculation path through which the recirculated exhaust flows and the first communication path. Thus, the recirculated exhaust gas flowing through the exhaust gas recirculation control valve, the first communication passage, and the suction passage is reconstituted with fresh air in the mixing passage according to the flow rate of fresh air that has a fixed relationship with the operating conditions of the internal combustion engine. It is mixed and supplied to the internal combustion engine. Therefore, the high-speed drive valve that is driven according to the operating conditions of the internal combustion engine as in the prior art is not used, and the structure becomes simple, so that the recirculated exhaust gas and fresh air can be mixed with a small physique.

  In the exhaust gas recirculation device of the present invention, the exhaust gas recirculation control valve is opened when negative pressure is generated after a certain amount of fresh air flows through the ejector, and the fresh air and the recirculated exhaust gas are mixed. Thereby, only the fresh air is supplied to the combustion chamber of the internal combustion engine in the intake stroke at the initial stage of the supply of the intake air, and the air-fuel mixture of the fresh air and the recirculated exhaust gas is supplied at a later stage of the intake air supply. Therefore, it is possible to adjust the concentration distributions of fresh air and recirculated exhaust in the combustion chamber.

1 is a schematic view of an engine system to which an exhaust gas recirculation device according to a first embodiment is applied. It is a mimetic diagram showing the top of the cylinder of the engine of the engine system to which the exhaust gas recirculation device by a 1st embodiment is applied. It is sectional drawing of the ejector and check valve of the exhaust gas recirculation apparatus by 1st Embodiment. It is a characteristic view explaining the action | operation of the exhaust gas recirculation apparatus by 1st Embodiment. It is a whole schematic diagram of an engine system to which an exhaust gas recirculation device according to a second embodiment is applied. It is sectional drawing of the ejector and check valve of the exhaust gas recirculation apparatus by 2nd Embodiment. It is a characteristic view explaining the action | operation of the exhaust gas recirculation apparatus by 2nd Embodiment.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows an engine system 1 to which the exhaust gas recirculation device 20 according to the first embodiment is applied.
The engine system 1 includes an engine 11 as an “internal combustion engine”, an intake system 12, an exhaust system 13, an exhaust gas recirculation device 20, an ECU 14, and the like. In the present embodiment, the gas in the atmosphere passing through the intake system 12 is referred to as “fresh air”. The gas discharged from the engine 11 is called “exhaust”. A part of the exhaust gas recirculated to the fresh air by the exhaust gas recirculation device 20 is referred to as “recirculation exhaust gas”. Further, the mixture of fresh air and reflux exhaust gas mixed in the ejector 30 of the exhaust gas recirculation device 20 and supplied to the combustion chamber 110 is referred to as “intake”. Note that, due to the operation of the exhaust gas recirculation device 20, there may be only “new air” in which “recirculation exhaust” is not included in “intake air”. 1 to 3, the flow of “fresh air” is indicated by an arrow F1. The flow of “reflux exhaust” is indicated by an arrow F2. The flow of “intake” is indicated by an arrow F12. The flow of “exhaust” is indicated by an arrow F3.

  The engine 11 is, for example, a direct injection internal combustion engine, which is a diesel engine that uses light oil as fuel. The engine 11 includes a plurality of combustion chambers 110, and a fuel injection valve 112 that directly injects diesel fuel is attached to a cylinder block 111 that forms each combustion chamber 110. In the engine 11, the intake valve 118 opens and the piston 113 descends downward in FIG. 1, so that intake air in the intake system 12 is introduced into the combustion chamber 110 via an intake port 114 formed in the cylinder block 111. (Intake stroke). The intake air introduced into the combustion chamber 110 is compressed to a high temperature (compression stroke) and burns when diesel fuel is injected into the combustion chamber 110 by the fuel injection valve 112, and the piston 113 is pushed down by the pressure generated during combustion. (Explosion process). When the pushed-down piston 113 rises again, the exhaust valve 119 opens to discharge the burned gas in the combustion chamber 110 as exhaust through the exhaust port 115 (exhaust stroke). Thereafter, when the piston 113 descends again, fresh air or intake air in the intake system 12 is introduced into the combustion chamber 110 via the intake port 114.

  The intake system 12 is provided to communicate the atmosphere with the intake port 114, and includes an intake pipe 120, an air cleaner 121, a throttle valve 122, an intake manifold 123, and the like. The intake system 12 introduces air in the atmosphere into the combustion chamber 110, and introduces part of the exhaust gas, which will be described later, into the combustion chamber 110, which is recirculated to fresh air.

The air cleaner 121 is provided on the most upstream side of the intake system 12 and removes foreign matters contained in fresh air flowing into the intake pipe 120.
The throttle valve 122 is provided on the downstream side of the air cleaner 121 and adjusts the amount of fresh air flowing through the intake pipe 120. The throttle valve 122 is provided with a motor 124 that adjusts the opening degree of the throttle valve 122. Further, the intake pipe 120 is provided with a throttle opening sensor 125, which detects the opening of the throttle valve 122.

The intake manifold 123 includes a surge tank 126 connected to the intake pipe 120 and a manifold 127 connecting the surge tank 126 and the intake port 114 of the engine 11.
The surge tank 126 has a larger passage cross-sectional area than the intake pipe 120 or the like, and relieves pulsation of fresh air or intake air flowing through the intake manifold 123.

The manifold 127 distributes fresh air in the surge tank 126 to each cylinder of the engine 11. As shown in FIG. 2, the manifold 127 according to the present embodiment includes two intake pipes for each cylinder of the engine 11.
FIG. 2 is an enlarged view of the top of the cylinder block 111 of the engine 11 where the intake port 114 and the exhaust port 115 are formed. A swirl flow intake pipe 128 is connected to one of the two intake ports 114 formed in the cylinder block 111. The intake air introduced from the swirl flow intake pipe 128 into the combustion chamber 110 forms a swirling flow in the direction perpendicular to the central axis of the cylinder block 111 in the combustion chamber 110, that is, a tumble flow. Further, the intake air introduced into the combustion chamber 110 from the tumble flow intake pipe 129 connected to the other intake port 114 is a swirling flow parallel to the central axis of the cylinder block 111 in the combustion chamber 110, that is, a swirl flow. Form. An ejector 30 of the exhaust gas recirculation device 20 described later is connected to a tumble flow intake pipe 129. The tumble flow intake pipe 129 corresponds to a “first pipe” recited in the claims.

  The exhaust system 13 is provided so as to communicate the exhaust port 115 and the atmosphere, and includes an exhaust manifold 131, an exhaust pipe 130, a catalyst 132, and the like. The exhaust system 13 releases the exhaust gas to the atmosphere and supplies a part of the exhaust gas as a recirculated exhaust gas to an exhaust gas recirculation device 20 described later.

  The exhaust manifold 131 connects the exhaust port 115 and the exhaust pipe 130 of each cylinder of the engine 11. In this embodiment, as shown in FIG. 2, two exhaust ports 115 are provided for each cylinder. Exhaust gas that has passed through the exhaust manifold 131 flows through the exhaust pipe 130.

  The exhaust pipe 130 has one end connected to the side opposite to the side connected to the exhaust port 115 of the exhaust manifold 131 and the other end communicating with the atmosphere. Exhaust gas flowing through the exhaust pipe 130 passes through the catalyst 132 provided in the exhaust pipe 130, whereby nitrogen oxides, unburned carbon, and the like contained in the exhaust gas are removed. The exhaust gas that has passed through the catalyst 132 is released to the atmosphere.

  The exhaust gas recirculation device 20 is provided so that the intake system 12 and the exhaust system 13 can communicate with each other. The exhaust gas recirculation device 20 mixes a part of the exhaust gas flowing through the exhaust system 13 with fresh air flowing through the intake system 12. Details of the exhaust gas recirculation device 20 will be described later.

  An electronic control circuit (hereinafter referred to as “ECU”) 14 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM. The engine system 1 is provided with a coolant temperature sensor 116 that detects the temperature of coolant of the engine 11 and a crank angle sensor 117 that outputs a pulse signal each time the crankshaft 15 rotates a predetermined crank angle. The ECU 14 receives information on the operating state such as the opening degree of the throttle valve 122 detected by the throttle opening degree sensor 128, the temperature of the cooling water in the cylinder block 111, and the rotation angle of the crankshaft 15. The ECU 14 controls the fuel injection amount, the throttle opening degree, etc. according to these pieces of information.

Next, the structure of the exhaust gas recirculation device 20 will be described.
The exhaust gas recirculation device 20 includes a first exhaust gas recirculation pipe 21, an ejector 30, and an exhaust gas recirculation control valve 40. The first exhaust gas recirculation pipe 21 has one end connected to the exhaust pipe 130 and the other end connected to the exhaust gas recirculation control valve 40. Part of the exhaust gas flowing through the exhaust pipe 130 flows into the first exhaust gas recirculation passage 211 formed by the first exhaust gas recirculation pipe 21.

  The ejector 30 is formed from a substantially cylindrical metal member. As shown in FIG. 3, the ejector 30 includes a first communication passage forming portion in which an introduction portion 31 through which fresh air in the tumble flow intake pipe 129 flows, a throttle portion 32, a suction passage formation portion 33, and a first communication passage 341 are formed. 34, a mixing unit 35, a discharge unit 36, and the like. The introduction part 31, the throttle part 32, the suction passage forming part 33, the first communication path forming part 34 in which the first communication path 341 is formed, and the mixing part 35 are integrally formed, for example.

  The introduction part 31 is formed on the atmosphere side of the ejector 30 as shown in FIG. The introduction portion 31 has a cylindrical shape, and a flow passage 311 through which fresh air in the tumble flow intake pipe 129 flows is formed on the central axis. The introduction portion 31 is fixed to the end portion 312 of the atmospheric tumble flow intake pipe 129.

  The throttle part 32 is connected to the side opposite to the side fixed to the end 312 of the introduction part 31. A throttle passage 321 communicating with the flow passage 311 is formed on the central axis of the throttle portion 32. The inner diameter of the throttle passage 321 decreases from the left side of FIG. 3 to the right side, that is, from the atmosphere side to the engine 11 side. An outer wall 322 that forms an end portion of the throttle portion 32 on the engine 11 side is formed in a tapered shape toward the engine 11 side.

  The suction passage forming part 33 is provided on the radially outer side of the throttle part 32. A suction passage 331 is formed between the radially inner wall 332 of the suction passage forming portion 33 and the outer wall 322 of the throttle portion 32. The suction passage 331 is formed in an annular shape coaxially with the throttle passage 311, and has a smaller distance from the central axis of the throttle portion 32 toward the engine 11 side from the atmosphere side and the central axis of the throttle portion 32. It is composed of a passage with a constant distance. A passage having a constant distance with respect to the central axis of the throttle portion 32 communicates with the first communication passage 341.

  The first communication passage forming portion 34 is formed on one of the radially outer sides of the suction passage forming portion 33. The first communication path 341 formed by the first communication path forming portion 34 communicates with the communication chamber 411 of the exhaust gas recirculation control valve 40.

  The mixing unit 35 is provided so as to be connected to the end of the suction passage forming unit 33 on the engine 11 side. A mixing passage 351 formed on the central axis of the mixing portion 35 is formed on the downstream side of the restricting passage 321 and communicates with the restricting passage 321 and the suction passage 331. The mixing passage 351 mixes the fresh air flowing through the throttle passage 321 and the reflux exhaust flowing through the suction passage 331 to make “intake”.

  The discharge unit 36 is connected to the end of the mixing unit 35 on the engine 11 side, and is provided on the most downstream side in the ejector 30. The discharge portion 36 has a cylindrical shape, and a flow passage 361 through which the intake air of the mixing passage 351 flows is formed on the central axis. The discharge portion 36 is fixed to an end portion 362 on the atmosphere side of the tumble flow intake pipe 129 on the engine 11 side.

  The exhaust gas recirculation control valve 40 includes a first sleeve 41, a second sleeve 42 connected to the first sleeve 41, a spool 43, a second communication path forming portion 44, an urging member 45 as an “urging means”, and the like. Is done. The exhaust gas recirculation control valve 40 connects the first exhaust gas recirculation pipe 21 and the ejector 30 and controls the supply of the recirculated exhaust gas flowing through the first exhaust gas recirculation passage 211 to the ejector 30.

  The first sleeve 41 and the second sleeve 42 are integrally formed in a substantially cylindrical shape. In the present embodiment, the inner diameter of the first sleeve 41 is formed larger than the inner diameter of the second sleeve 42. The first sleeve 41 slidably accommodates the first land 431 of the spool 43. The second sleeve 42 slidably accommodates the second land 432 of the spool 43. The communication chamber 411 formed between the first land 431 and the inner wall 412 of the first sleeve 41 can communicate with the first exhaust recirculation passage 211 and the first communication passage 341 by the movement of the spool 43. Further, a pressure chamber 421 is formed between the second land 432 and the inner wall 422 of the second sleeve 42, and the pressure chamber 421 is first through the second communication passage 441 formed by the second communication passage forming portion 44. It communicates with the communication path 341. The first sleeve 41 and the second sleeve 42 correspond to a “sleeve” recited in the claims.

  The spool 43 has a first land 431 and a second land 432. The first land 431 and the second land 432 are connected so as not to change the distance between them. Therefore, when the second land 432 moves, the first land 431 also moves by the same distance as the second land 432.

  One end of the biasing member 45 is locked to the pressure chamber 421 side of the second land 432, and the other end is locked to the inner wall of the second sleeve 42. The biasing member 45 has a biasing force that biases the spool 43 upward in FIG. 3 so as to reduce the volume of the communication chamber 411.

The exhaust gas recirculation control valve 40 communicates or blocks the first communication path 341 and the first exhaust gas recirculation path 211 depending on the relationship between the pressure of the first communication path 341 and the pressure of the first exhaust gas recirculation path 211.
When the pressure of the first communication path 341 is lower than the pressure of the first exhaust gas recirculation path 211 and is equal to or lower than a predetermined pressure, the pressure of the pressure chamber 421 communicating with the first communication path 341 decreases, and the spool 43 is Move down. When the first land 431 of the spool 43 is separated from the side where the first exhaust recirculation pipe 21 of the first sleeve 41 is connected, and the communication chamber 411 and the first communication passage 341 communicate with each other, the first land 431 is communicated via the communication chamber 411. The exhaust gas recirculation passage 211 and the first communication passage 341 communicate with each other. As a result, the recirculated exhaust gas from the first exhaust recirculation passage 211 flows into the first communication passage 341. The predetermined pressure is determined by the force that the recirculation exhaust of the first exhaust recirculation passage 211 acts on the end face of the first land 431 on the first exhaust recirculation passage 211 side, and the recirculation exhaust of the pressure chamber 421 is the second land 432 second. It is calculated from the relationship between the force acting on the end surface on the communication path 441 side and the force with which the biasing member 45 biases the spool 43.

When the pressure of the first communication passage 341 is lower than the pressure of the first exhaust recirculation passage 211 but higher than a predetermined pressure, the communication chamber 411 and the first communication passage 341 do not communicate with each other, and therefore the recirculation exhaust of the first exhaust recirculation passage 211 Does not flow into the first communication path 341.
Further, when the pressure of the first communication passage 341 is higher than the pressure of the first exhaust gas recirculation passage 211, the spool 43 abuts on the end of the first sleeve 41 on the side to which the first exhaust gas recirculation pipe 21 is connected, Since the communication chamber 411 and the first communication passage 341 do not communicate with each other, the recirculated exhaust gas in the first exhaust recirculation passage 211 does not flow into the first communication passage 341.

Next, the operation of the exhaust gas recirculation device 20 will be described.
In the intake stroke of the engine system 1, when the piston 113 descends, the combustion chamber 110 becomes negative pressure. When the intake valve 118 is opened, fresh air in the intake pipe 120 flows in the direction of the combustion chamber 110 due to the negative pressure of the combustion chamber 110. When fresh air in the intake pipe 120 passes through the throttle portion 32 of the ejector 30, the flow rate of fresh air increases. In the ejector 30, negative pressure is generated on the downstream side of the throttle portion 32 due to the fresh air flowing at high speed from the throttle passage 321 toward the mixing passage 351, and the recirculated exhaust gas in the suction passage 331 is sucked. The sucked recirculated exhaust gas is mixed with fresh air in the mixing unit 35 to form intake air. The formed intake air is supplied to the combustion chamber 110.

  Here, the operation of the exhaust gas recirculation control valve 40 in the intake stroke of the engine system 1 will be described based on the load of the engine 11.

  FIG. 4 is a diagram showing the relationship between the amount of intake air supplied to the combustion chamber 110 and time. FIG. 4A shows the relationship between the intake air amount per unit time and time when the load of the engine 11 is low, for example, when the rotational speed of the crankshaft 15 is low. FIG. 4B shows the relationship between the intake air amount per unit time and time when the load of the engine 11 is high, for example, when the rotation speed of the crankshaft 15 is high.

  In FIG. 4, a threshold value F is set for the amount of fresh air flowing through the tumble flow intake pipe 129 among the intake air supplied to the combustion chamber 110. When the amount of fresh air flowing through the tumble flow intake pipe 129 is larger than the threshold value F, the first communication path 341 becomes equal to or lower than a predetermined pressure due to the negative pressure generated by fresh air passing through the throttle portion 32. As a result, the exhaust gas recirculation control valve 40 is opened. Further, when the amount of fresh air flowing through the tumble flow intake pipe 129 is equal to or less than the threshold value F, the pressure in the first communication path 341 is also greater than the predetermined pressure due to the negative pressure generated by the fresh air passing through the throttle portion 32. As a result, the exhaust gas recirculation control valve 40 maintains the closed state. The amount of fresh air flowing through the tumble flow intake pipe 129 is determined by the load of the engine 11.

  When the load of the engine 11 is low, the pressure of the combustion chamber 110 in the intake stroke is not so small, so the amount of fresh air that passes through the throttle portion 32 is less than the threshold value F. In this case, since the pressure in the first communication path 341 is larger than the predetermined pressure, the exhaust gas recirculation control valve 40 maintains the closed state, and the first exhaust gas recirculation path 211 and the first communication path 341 remain blocked. Become. Therefore, as shown by a curve L10 in FIG. 4A, the amount of intake air per unit time is the same as the amount of fresh air flowing through the intake pipe 120, and only fresh air is supplied to the combustion chamber 110.

  On the other hand, when the load on the engine 11 is high, the pressure in the combustion chamber 110 during the intake stroke is smaller than when the load on the engine 11 is low, so the amount of fresh air passing through the throttle portion 32 is greater than the threshold value F. In this case, when the flow rate of fresh air passing through the throttle portion 32 increases, the pressure in the first communication path 341 becomes equal to or lower than a predetermined pressure at time t1. At time t1, the spool 43 moves downward in FIG. 3, and the first exhaust gas recirculation passage 211 and the first communication passage 341 communicate with each other through the communication chamber 411. As a result, the recirculated exhaust gas in the first exhaust recirculation passage 211 is introduced into the mixing unit 35 through the first communication passage 341 and the suction passage 331. In the mixing unit 35, fresh air and recirculated exhaust gas are mixed and supplied to the combustion chamber 110 as intake air.

  When the flow rate of fresh air passing through the throttle portion 32 decreases, the pressure of the first communication passage 341 becomes higher than a predetermined pressure, so that the spool 43 moves upward in FIG. 3 and the first exhaust gas recirculation passage 211 and the first The communication path 341 is shut off (time t2 in FIG. 4B). As a result, the recirculated exhaust gas does not flow into the first communication path 341, and thus the recirculated exhaust gas is not supplied to the mixing unit 35. When the intake valve 118 is closed at time t3, the supply of intake air to the combustion chamber 110 is stopped (time t3 in FIG. 4B).

  Thus, when the load on the engine 11 is relatively high, only fresh air is introduced into the combustion chamber 110 from time t0 to time t1 when the intake valve 118 is opened, as shown by a curve L11 in FIG. , And a mixture of fresh air and recirculation exhaust is supplied from time t1 to time t2, and only fresh air is supplied from time t2 to time t3. A hatched portion A surrounded by the curve L11 and the straight line L0 indicating the threshold value F in FIG. 4B indicates the amount of the recirculated exhaust gas supplied to the combustion chamber 110.

  In the exhaust gas recirculation device 20 according to the first embodiment, the amount of the recirculated exhaust gas mixed into the fresh air is controlled according to the magnitude of the negative pressure generated by the fresh air passing through the throttle portion 32 of the ejector 30. When the flow rate of fresh air passing through the throttle portion 32 is slow, the first communication path 341 becomes larger than a predetermined pressure, and the exhaust gas recirculation control valve 40 maintains the closed state. As a result, only fresh air is supplied to the combustion chamber 110. On the other hand, when the flow rate of fresh air passing through the throttle portion 32 is high, the first communication path 341 becomes lower than a predetermined pressure via the suction path 331, and the exhaust gas recirculation control valve 40 is opened. Thereby, the recirculated exhaust gas is supplied to the combustion chamber 110 together with fresh air. In this way, the exhaust gas recirculation device 20 can control the mixing amount of the recirculated exhaust gas in accordance with the amount of fresh air that is related to the operating conditions of the engine 11. Therefore, the exhaust gas recirculation device 20 can mix the recirculated exhaust gas and fresh air with a small physique without using a high-speed drive valve that is driven in accordance with the operating conditions of the engine.

  Further, in the exhaust gas recirculation device 20, only the fresh air is supplied at the initial stage of the intake air supply during the time when the intake air is supplied to the combustion chamber 110, and the recirculated exhaust gas and the fresh air introduced into the mixing unit in the middle of the intake air supply. Is supplied to the combustion chamber 110, and only fresh air is supplied in the latter half of the intake air supply. That is, it is possible to make a time difference between the timing at which only fresh air having a relatively high oxygen concentration is supplied and the timing at which a mixture of recirculated exhaust gas having a low oxygen concentration and fresh air is supplied. Thereby, the oxygen concentration distribution of the combustion chamber 110 and the concentration distribution of unburned carbon contained in the recirculated exhaust gas can be adjusted. Therefore, it is possible to realize an environment of a combustion chamber capable of performing stratified combustion for the purpose of reducing nitrogen oxides and promoting combustion of unburned carbon.

  In the exhaust gas recirculation control valve 40, the spool 43 moves in accordance with the magnitude of the negative pressure generated by the flow of fresh air, and communicates or blocks the first exhaust gas recirculation passage 211 and the first communication passage 341. Thereby, energy, such as electricity, is not required when driving the exhaust gas recirculation device 20. Therefore, the exhaust gas recirculation device 20 can mix the recirculated exhaust gas and fresh air with a simple configuration.

  Further, when the pressure in the first communication path 341 is higher than a predetermined pressure, the exhaust gas recirculation control valve 40 does not open. Thereby, the exhaust gas recirculation control valve 40 can prevent the backflow of fresh air and recirculated exhaust gas from the intake system 12 to the exhaust system 13.

(Second Embodiment)
Next, an exhaust gas recirculation apparatus according to a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, unlike the first embodiment, the exhaust gas recirculation device is connected to the intake system at two locations via an exhaust gas recirculation control valve. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted.

  The exhaust gas recirculation device 50 according to the second embodiment is provided with two paths for recirculating the recirculated exhaust gas from the exhaust gas recirculation control valve 60 to the intake system 12. One is a path that recirculates through the same ejector 30 as in the first embodiment, and the other is a path that recirculates to the intake pipe 120 upstream of the ejector 30 of the intake system 12.

  FIG. 6 shows a cross-sectional view of the exhaust gas recirculation valve 60 and the ejector 30 of the exhaust gas recirculation device 50. A first communication path is formed in the first sleeve 61 of the exhaust gas recirculation valve 60 so that a communication chamber 611 formed by the first land 431 and the inner wall 612 of the first sleeve 61 and the first communication path 341 can communicate with each other. The part 34 is connected, and the second exhaust gas recirculation pipe 66 is connected so that the second exhaust gas recirculation passage 661 can communicate with the communication chamber 611. The end of the second exhaust recirculation pipe 66 opposite to the side connected to the first sleeve 61 is connected to the intake pipe 120 on the downstream side of the throttle valve 122 of the intake pipe 120 as shown in FIG. 5 and 6, the flow of “primary intake”, which is a mixture of the recirculated exhaust gas flowing through the second exhaust gas recirculation passage 661 and the fresh air flowing through the intake pipe 120, is indicated by an arrow F22. In addition, a flow of “secondary intake” that is an air-fuel mixture of “primary intake” and recirculated exhaust gas flowing through the first communication passage 341 is indicated by an arrow F23.

Here, the operation of the exhaust gas recirculation device 50 according to the second embodiment will be described based on the load of the engine 11.
FIG. 7 is a diagram showing the relationship between the amount of intake air supplied to the combustion chamber 110 and time. FIG. 7A shows the relationship between the intake air amount per unit time and time when the load of the engine 11 is relatively low. FIG. 7B shows the relationship between the intake air amount per unit time and time when the load of the engine 11 is relatively high.

  When the load of the engine 11 is low, the pressure of the combustion chamber 110 in the intake stroke is not so small, so the amount of fresh air that passes through the throttle portion 32 is less than the threshold value F. In this case, since the pressure in the first communication path 341 is larger than the predetermined pressure, the exhaust gas recirculation control valve 60 maintains the closed state, and the first exhaust gas recirculation path 211, the first communication path 341, and the second exhaust gas recirculation path 661. And remain blocked. Therefore, as shown by a curve L20 in FIG. 7A, the amount of intake air per unit time is the same as the amount of fresh air flowing through the intake pipe 120, and only fresh air is supplied to the combustion chamber 110.

  On the other hand, when the load on the engine 11 is high, the amount of fresh air that passes through the throttle unit 32 is greater than the threshold value F. In this case, the pressure in the first communication path 341 becomes equal to or lower than a predetermined pressure at time t1. At time t1, the spool 43 moves downward in FIG. 6, and the first exhaust gas recirculation passage 211, the first communication passage 341, and the second exhaust gas recirculation passage 611 communicate with each other. As a result, the recirculated exhaust gas in the first exhaust recirculation passage 211 is introduced into the mixing unit 35 through the first communication passage 341 and the suction passage 331, and a part of the recirculated exhaust gas in the first exhaust recirculation passage 211 is second exhaust gas. The air is recirculated to the intake pipe 120 on the upstream side of the ejector 30 through the recirculation passage 661. That is, the recirculated exhaust gas supplied through the first communication passage 341 and the suction passage 331 is further mixed with the primary intake air upstream of the ejector 30.

  When the flow rate of fresh air passing through the throttle portion 32 decreases, the pressure of the first communication passage 341 becomes higher than a predetermined pressure, so that the spool 43 moves upward in FIG. 6 and the first exhaust gas recirculation passage 211 and the first The communication path 341 and the second exhaust gas recirculation path 661 are shut off (time t2 in FIG. 7B). However, in the exhaust gas recirculation device 50, a part of the recirculated exhaust gas is recirculated on the upstream side of the ejector 30, and the exhaust gas recirculation control valve 60 is closed at time t2, as indicated by a curve L21 in FIG. Later, the secondary intake air supplied to the combustion chamber 110 includes the recirculated exhaust gas. After time t2, the mixture of recirculated exhaust gas and fresh air supplied upstream of the ejector 30 passes through the ejector 30, and the intake valve 118 is closed to stop the supply of intake air to the combustion chamber 110 (FIG. 7 (b), time t3).

  A hatched portion B surrounded by the curve L21 in FIG. 7B and the straight line L0 indicating the threshold value F indicates the amount of the recirculated exhaust gas supplied to the combustion chamber 110, and the exhaust recirculation device according to the first embodiment. It is wider than the shaded area A surrounded by the 20 curves L11 and the straight line L0. That is, in the exhaust gas recirculation device 50 according to the second embodiment, a larger amount of the recirculated exhaust gas is mixed with fresh air than the exhaust gas recirculation device 20 according to the first embodiment.

  In the exhaust gas recirculation apparatus 50 according to the second embodiment, by returning a part of the recirculated exhaust gas to the upstream side of the ejector 30, the amount of recirculated exhaust gas contained in the intake air can be increased. In particular, during the time when the intake air is supplied to the combustion chamber 110 (between the time t0 and the time t3 in FIG. 7B), the concentration of the recirculated exhaust gas in the intake air supplied at the latter supply stage can be increased. Thus, when the intake air is supplied into the combustion chamber 110, the exhaust gas concentration in the vicinity of the intake port 114 of the combustion chamber 110 can be increased, which can contribute to the reduction of nitrogen oxides. Therefore, the exhaust gas recirculation device 60 of the second embodiment can control the concentration and amount of the recirculated exhaust gas in the intake air in a wider range than the first embodiment, in addition to the effects of the first embodiment.

(Other embodiments)
(A) In the above-described embodiment, the engine is a direct injection diesel engine. However, the type of engine is not limited to this. The engine may be a type in which fuel is mixed with fresh air, intake air, primary intake air, or secondary intake air in the intake pipe, or an engine using gasoline as fuel.

  (B) In the above-described embodiment, two intake ports are formed in the cylinder. However, the number of intake ports is not limited to this. There may be one. In this case, the exhaust gas recirculation device of the present invention is connected to an intake pipe connected to the one intake port.

  (C) In the above-described embodiment, the ejector is provided in the tumble flow intake pipe of the intake manifold. However, the position where the ejector is arranged is not limited to this. What is necessary is just to be downstream from the air cleaner provided in the intake pipe and upstream from the intake port to which the intake manifold is connected.

  (D) In the above-described embodiment, one end of the exhaust gas recirculation pipe is connected to the exhaust pipe. However, the position where the exhaust gas recirculation pipe is connected is not limited to this. It may be downstream of the exhaust port connected to the exhaust manifold and upstream of the catalyst provided in the exhaust pipe.

  (E) In the above-described embodiment, the second exhaust gas recirculation pipe is connected to the intake pipe on the downstream side of the throttle valve provided in the intake pipe. However, the position where the second exhaust gas recirculation pipe is connected is not limited to this. It may be an intake pipe or an intake manifold located downstream of the air cleaner and upstream of the ejector.

  (F) In the above-described embodiment, the inner diameter of the first sleeve is larger than the inner diameter of the second sleeve. However, the magnitude relationship between the inner diameter of the first sleeve and the inner diameter of the second sleeve is not limited to this.

  As mentioned above, this invention is not limited to such embodiment, It can implement with a various form in the range which does not deviate from the summary.

11 ... Engine (internal combustion engine),
12 ・ ・ ・ Intake system,
13 ... exhaust system,
20, 50 ... exhaust gas recirculation device,
21 ... 1st exhaust gas recirculation pipe,
211... First exhaust gas recirculation passage,
30 ・ ・ ・ Ejector,
32...
321 ... throttle passage,
33 ・ ・ ・ Suction passage forming part,
331 ... suction passage,
34 ... 1st communicating path formation part,
341 ... 1st communication path,
35 ・ ・ ・ Mixing section,
351... Mixing passage,
40: Exhaust gas recirculation control valve.

Claims (7)

An exhaust gas recirculation device that mixes a part of exhaust gas flowing through an exhaust system (13) of an internal combustion engine (11) with recirculated exhaust gas and fresh air flowing through the intake system (12) of the internal combustion engine,
A first exhaust gas recirculation pipe (21) having one end connected to the exhaust system and forming a first exhaust gas recirculation passage (211) through which recirculated exhaust gas from the exhaust system to the intake system flows;
A throttle portion (32) provided in the intake system and forming a throttle passage (321) for reducing the cross-sectional area of fresh air flowing from the upstream side to the downstream side of the intake system, and the return of the first exhaust gas recirculation pipe A suction passage forming portion (33) that forms a suction passage (331) through which the exhaust flows radially outside the throttle portion, and a mixing passage (351) that mixes fresh air that flows through the throttle passage and reflux exhaust gas that flows through the suction passage. ) On the downstream side of the throttle passage, and an ejector (30) having a first communication passage forming portion (34) forming a first communication passage (341) communicating with the suction passage. When,
The first exhaust gas recirculation passage and the first communication passage are provided so as to communicate with each other, and when the pressure of the first communication passage is equal to or lower than a predetermined pressure, the first exhaust gas recirculation passage and the first communication passage are An exhaust recirculation control valve (40) in communication;
An exhaust gas recirculation device comprising:   A second exhaust gas recirculation pipe (66) connected to the exhaust gas recirculation control valve and recirculating a part of the recirculated exhaust gas flowing through the first exhaust gas recirculation passage to the upstream side of the ejector of the intake system is provided. The exhaust gas recirculation apparatus according to claim 1. The exhaust gas recirculation control valve is
A spool (43);
The first exhaust gas recirculation pipe and the first communication passage forming portion are connected, the spool is slidably accommodated, and the first exhaust gas recirculation passage and the one end portion (431) of the spool are A sleeve that forms a communication chamber (411) that allows communication with the first communication passage, and a pressure chamber (421) that can communicate with the first communication passage between the other end (432) of the spool. (41, 42),
A second communication path forming portion (44) that forms a second communication path (441) that communicates the pressure chamber and the first communication path;
Biasing means (45) for biasing the spool in a direction to reduce the volume of the communication chamber;
With
The first exhaust passage and the first communication passage are communicated with each other through the communication chamber when the pressure of the first communication passage is equal to or lower than a predetermined pressure. Exhaust gas recirculation device.   The exhaust gas recirculation device according to any one of claims 1 to 3, wherein the exhaust gas recirculation control valve is a check valve that prevents a reverse flow of the recirculated exhaust gas to the first exhaust gas recirculation passage. Each of the cylinders of the internal combustion engine has two intake ports (158) for supplying fresh air or a mixture of fresh air and recirculated exhaust to the combustion chamber of each cylinder,
The exhaust gas recirculation apparatus according to any one of claims 1 to 4, wherein the ejector is provided in a first pipe (129) connected to one of the intake ports.   The first pipe supplies fresh air or a mixture of fresh air and recirculated exhaust gas to the combustion chamber of the internal combustion engine so as to form a tumble flow in the combustion chamber of the internal combustion engine. To 5. The exhaust gas recirculation apparatus according to any one of claims 1 to 5.   The exhaust gas recirculation apparatus according to any one of claims 1 to 6, wherein the exhaust gas recirculation apparatus is applied to a direct injection internal combustion engine that directly injects fuel into a combustion chamber of the internal combustion engine.

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