JP4974994B2 - Intake device for internal combustion engine - Google Patents

Description

  The present invention controls an intake air flow of an internal combustion engine having an exhaust gas recirculation device that circulates a part of exhaust gas from an exhaust pipe to an intake pipe by an exhaust gas circulation pipe, and is provided in the intake pipe to adjust the intake air flow. The present invention relates to an intake device for an internal combustion engine that includes an intake flow control valve that controls the control and a control device that controls the control valve.

2. Description of the Related Art An in-vehicle internal combustion engine is known that includes an exhaust gas recirculation device (hereinafter referred to as “EGR device”) that circulates part of exhaust gas to an intake pipe.
As described in Patent Document 1, the EGR device is composed of an EGR pipe connected to the intake pipe from the middle of the exhaust pipe, and an EGR valve provided in the middle of the EGR pipe. The amount of EGR gas fed into the intake pipe is adjusted.

  Since the EGR gas supplied to the intake pipe is fed into the combustion chamber, the combustion temperature of the air-fuel mixture is reduced by non-combustible gas such as carbon dioxide and water vapor contained in the EGR gas. The amount of generation will be reduced.

In recent years, EGR devices are also used in gasoline engines to reduce heat loss of explosive energy and improve fuel efficiency. In order to improve fuel efficiency, it is necessary to secure a large amount of circulating EGR gas and to control it in accordance with the engine state.
Japanese Patent Laid-Open No. 11-2158

  By the way, when the throttle valve is driven to close and the opening degree of the EGR valve is controlled, the amount of EGR gas increases relative to the amount of intake air sent into the combustion chamber. Will end up. When the ratio of the EGR gas to the intake air amount fed into the combustion chamber (hereinafter referred to as “EGR rate”) increases excessively, problems such as unstable combustion occur.

  In order to avoid such a problem, it is conceivable that when the throttle valve is driven to the valve closing side, the EGR valve is also driven to the valve closing side to reduce the EGR gas amount. In this case, although the EGR valve is driven to the closed side in accordance with a request for reducing the amount of EGR gas, the EGR valve is generally less responsive than the throttle valve. Even if the EGR valve is completely closed, the EGR gas remaining in the EGR pipe downstream of the EGR valve at that time flows into the intake pipe. In other words, even if the opening / closing of the EGR valve is completely synchronized with the opening / closing of the throttle valve, the EGR gas decrease is delayed with respect to the decrease of the intake air amount, and the EGR rate after the throttle valve is closed temporarily It is shown that an inevitable rise is inevitable.

  In particular, when the driver operates the accelerator pedal with a sudden throttle valve closing drive, the amount of fresh air decreases rapidly, while the decrease in the amount of EGR gas due to the driving of the EGR valve causes a decrease in fresh air. On the other hand, the EGR rate increases because of delay. The EGR rate correlates with the occurrence of misfire, and an increase in the EGR rate may cause the occurrence of misfire. That is, it is conceivable that instability of combustion occurs due to an increase in the EGR rate in the rapid closing control of the throttle valve.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an intake device for an internal combustion engine that can suppress the deterioration of the combustion state caused by the exhaust gas recirculated to the intake pipe. There is to do.

In the following, means for achieving the above object and its effects are described.
(1) The invention according to claim 1 controls the intake air flow of an internal combustion engine including an exhaust gas recirculation device that circulates part of the exhaust gas from the exhaust pipe to the intake pipe by the exhaust gas circulation pipe. An intake device for an internal combustion engine comprising an intake flow control valve that is provided in a pipe and adjusts the intake flow, and a control device that controls the control valve. The proximity portion, which is a portion, is located closest to the opening of the exhaust gas recirculation pipe with respect to the intake pipe, so that the portion on the intake passage side of the opening is closer to the intake upstream side and the intake downstream side of the same portion. The control device is configured to form a low-pressure portion, and the control device is configured to control the intake air flow more than before the reduction request is generated when there is a request to reduce the exhaust gas flow rate and the intake flow control valve is at the predetermined opening. Proximity of the valve to the opening Is summarized in that in the direction away performs a separation control for driving the same control valve.

  According to the present invention, when the intake flow control valve is at a predetermined opening, the low pressure part is formed on the intake passage side of the opening of the exhaust recirculation pipe, so that the exhaust recirculation pipe has a different opening. It is possible to increase the exhaust ring flow rate more than the time. In other words, the pressure at the portion on the intake passage side of the opening is lower than the pressure on the intake upstream side and the intake downstream side due to the venturi effect, so that the flow velocity of the intake air passing through the portion increases, thereby The amount of exhaust gas circulated from the recirculation pipe to the intake passage increases.

  As described above, the exhaust flow rate can be increased by operating the intake flow control valve. However, when there is a request to reduce the exhaust flow rate and the intake flow control valve is at a predetermined opening, that is, when the throttle valve suddenly increases. When there is a demand to reduce the exhaust ring flow rate based on a proper valve closing operation, etc., the exhaust ring flow rate is increased to the maximum by the intake flow control valve. There is a concern that the combustion state may deteriorate due to insufficient reduction of the flow rate.

  In view of this point, in the above invention, the exhaust flow control valve is requested to decrease and the intake flow control valve is controlled to be separated when the intake flow control valve is at a predetermined opening, that is, by the intake flow control valve. Since the increase effect of the exhaust gas flow rate is reduced, it is possible to suppress the deterioration of the combustion state due to the exhaust gas recirculated to the intake pipe. Note that the predetermined opening degree of the intake flow control valve is not limited to a specific opening degree, but other opening degrees that form a substantially low pressure state in a portion on the intake passage side of the opening. Can also be included.

  (2) The invention described in claim 2 is the intake device for an internal combustion engine according to claim 1, wherein the intake flow control valve adjusts the generation mode of the vortex flow in the combustion chamber based on the opening / closing operation thereof. There is a summary.

  (3) The invention according to claim 3 is the intake device for an internal combustion engine according to claim 2, wherein the intake flow control valve has an opening degree when driven to the maximum in the direction of increasing the vortex flow. The gist is that the opening degree is a predetermined degree.

  (4) The invention according to claim 4 is the intake device for an internal combustion engine according to claim 2 or 3, wherein the intake flow control valve is driven to the maximum in a direction to reduce the vortex flow. The gist is that it is accommodated in an accommodating portion provided in the pipe.

  According to the present invention, when the intake flow control valve is driven to the maximum in the direction of reducing the vortex flow, the intake air flowing through the intake passage is not blocked by the control valve. That is, the pressure loss due to the intake flow control valve in the same state can be reduced.

  (5) The invention according to claim 5 is the intake system for an internal combustion engine according to any one of claims 1 to 4, wherein when the control device has a request to increase the exhaust gas flow rate, the request is made. The gist is to bring the opening of the intake flow control valve closer to the predetermined opening than before the occurrence.

  According to the present invention, the action of increasing the exhaust gas flow rate by the intake flow control valve is enhanced, so that the exhaust gas flow rate increases more than before the demand for increasing the exhaust gas flow rate occurs under other conditions. This makes it possible to respond to the request more quickly.

  (6) The invention according to claim 6 is the intake device for an internal combustion engine according to any one of claims 1 to 5, wherein the exhaust gas recirculation device is provided in the exhaust gas recirculation pipe to reduce the exhaust gas recirculation flow rate. The exhaust gas recirculation valve to be adjusted is provided, and the control device performs the separation control when the exhaust gas recirculation valve operates to the valve closing side based on a request to reduce the exhaust gas flow rate. Is the gist.

  In general, the response of the exhaust gas recirculation valve is low, so even if the recirculation valve is driven to the closed side based on a request to reduce the exhaust gas flow rate, the exhaust gas recirculation amount will not reach the target level. It takes a relatively long time. In this regard, according to the above-described invention, the separation control is performed for the intake flow control valve having higher responsiveness than the recirculation valve in accordance with the operation on the valve closing side of the exhaust recirculation valve. Compared with the case where the exhaust ring flow rate is reduced through the operation, the exhaust ring flow rate can be rapidly reduced.

  (7) The invention according to claim 7 is the intake device for an internal combustion engine according to claim 6, wherein the control device performs the separation control until the ratio of the exhaust gas flow rate to the intake air amount becomes stable. The gist is to perform prohibition control for prohibiting the opening degree of the intake flow control valve from approaching the predetermined opening degree.

  In the present invention, by maintaining the opening degree of the intake flow control valve until the ratio of the exhaust gas flow rate to the intake air amount shows a stable value, it is possible to more suitably suppress the increase of the ratio of the exhaust air flow rate to the intake air amount. It becomes like this.

  (8) According to an eighth aspect of the present invention, in the intake device for an internal combustion engine according to the seventh aspect, after the control device executes the prohibition control, the ratio of the exhaust gas flow rate to the intake air amount is stabilized. The gist of the present invention is that the prohibition control is terminated based on the above, thereby permitting the opening degree of the intake flow control valve to approach the predetermined opening degree.

  (9) The invention according to claim 9 is the intake system for an internal combustion engine according to any one of claims 1 to 8, wherein the demand for reduction of the exhaust gas flow is from the intake flow control valve of the intake pipe. Also, the gist of the invention is that it is accompanied by a sudden closing of an intake air amount control valve that is provided upstream and controls the intake air amount.

  In the present invention, when a request to reduce the exhaust gas flow rate occurs when the intake air amount control valve is suddenly closed, the exhaust gas flow rate is preferably reduced by driving the exhaust gas flow valve to the closed side and the intake air flow control valve to the open side. I try to let them. When the intake air amount decreases, if the decrease in the exhaust ring flow rate flowing into the intake pipe lags behind the decrease in the intake air amount, the ratio of the exhaust ring flow rate temporarily increases. In particular, when the intake air amount control valve is suddenly closed, it is considered that this ratio is likely to increase. Therefore, by driving the intake air flow control valve to the open side when there is a decrease in the exhaust gas flow rate due to the sudden closing of the intake air amount control valve, the ratio of the exhaust gas flow rate to the intake air amount can be exceeded even in such a case. It is possible to suitably suppress a general increase.

With reference to FIGS. 1-4, one Embodiment which actualized this invention is described.
As shown in FIG. 1, an internal combustion engine 1 includes an engine body 10 that burns a mixture of intake air and fuel, and an intake device 20 that supplies intake air and fuel to a combustion chamber 11 of the engine body 10 through an intake pipe 21. And an exhaust device that sends out the gas after combustion in the combustion chamber 11 to the outside through the exhaust pipe 31. Furthermore, it is configured to include an EGR device 40 that is an exhaust gas recirculation device that circulates a part of the exhaust gas to the intake pipe 21 and a control device 50 that comprehensively controls various devices of the internal combustion engine.

  The engine body 10 includes a piston 14 that reciprocates through combustion of the air-fuel mixture in the combustion chamber 11, a crankshaft 15 that converts the reciprocating motion of the piston 14 into rotational motion, and a connection portion between the intake pipe 21 and the combustion chamber 11. And an exhaust valve 13 that opens and closes a connection portion between the exhaust pipe 31 and the combustion chamber 11.

  The intake device 20 includes an intake pipe 21 connected to the combustion chamber 11, a throttle valve 22 provided in the middle of the intake pipe 21 to change the intake passage area, a tumble control valve (hereinafter referred to as "TCV23"), It is comprised by. The TCV 23 is provided downstream of the valve 22 in the intake pipe 21 to generate a tumble flow in the air-fuel mixture in the combustion chamber 11 and adjust the generation mode. The TCV 23 is provided for each intake port of each cylinder.

  The EGR device 40 has an EGR pipe 41 connecting the exhaust pipe 31 and the intake pipe 21 as its main body, and an intake portion 43 provided in the middle of the exhaust pipe 31 and an introduction provided in the vicinity of the combustion chamber of the intake pipe 21. The intake pipe 21 and the exhaust pipe 31 are connected to each other by the portion 44. The position of the introduction part 44 of the EGR gas to the intake pipe 21 is set to a throttle part 21E where the passage area of the intake pipe 21 is narrowed by the valve tip 23T of the valve body of the TCV 23 provided in the vicinity of the combustion chamber 11 of the intake pipe 21. Is set. The introduction part 44 is installed for each TCV 23 provided for each intake port. An EGR valve 42 for controlling the introduction of EGR gas into the intake pipe 21 is provided in the middle of the EGR pipe 41. The EGR pipe 41 is divided into an upstream side 41A from the exhaust pipe 31 to the EGR valve 42 and a downstream side 41B from the EGR valve 42 to the intake pipe 21 by the EGR valve 42.

  The control device 50 includes various sensors that monitor the engine operating state, that is, various sensors including an accelerator position sensor 52, a throttle position sensor 53, an air flow meter 54, and an EGR position sensor 55, and the outputs of these devices. The electronic control device 51 controls the operation.

  The accelerator position sensor 52 changes its output in accordance with the depression amount of the accelerator pedal 24 of the vehicle (hereinafter referred to as “accelerator operation amount AP”), and is provided in the vicinity of the accelerator pedal. The throttle position sensor 53 has an output that changes according to the opening of the throttle valve 22 (hereinafter referred to as “throttle opening TA”), and is provided in the vicinity of the throttle valve 22. The air flow meter 54 changes its output in accordance with the flow rate of intake air flowing through the intake pipe 21 (hereinafter referred to as “intake amount GA”), and is provided on the intake upstream side of the throttle valve 22. The EGR position sensor 55 has an output that changes in accordance with the opening of the EGR valve 42 (hereinafter, “EGR opening EA”), and is provided in the vicinity of the EGR valve 42.

  The electronic control unit 51 controls the operation of the throttle valve 22 based on the engine operating state grasped based on the output of each sensor, the EGR control that controls the operation of the EGR device 40, and the TCV 23. Various types of control such as TCV control for controlling the operation are performed.

With reference to FIG. 2, the configuration of the vicinity of the EGR gas introduction portion 44 of the intake device 20 will be described in detail.
The TCV 23 includes a valve body 23B that changes the passage area in the intake pipe 21 and a TCV shaft 23A that serves as a rotation axis of the valve body 23B. The TCV shaft 23 </ b> A is provided on the wall portion of the intake pipe 21 and is driven by a separate actuator mounted on the internal combustion engine 1. The valve body 23B has a shape corresponding to the shape of the inner peripheral side of the intake pipe 21, and can maintain the intake passage between the wall surface of the intake pipe 21 even when it is closest to the valve closing side. It is constructed and installed as a disc valve. One of the end portions is attached to the TCV shaft 23A, and the other end portion (hereinafter referred to as “valve tip portion 23T”) is disposed downstream of the TCV shaft 23A in the intake passage.

  Then, when the valve body 23B is rotated together with the TCV shaft 23A by the actuator, the rotational position of the valve body 23B relative to the intake pipe 21, that is, the opening degree of the TCV 23 (hereinafter, “TCV opening degree VA”) is changed. The TCV opening VA includes an opening for maintaining the passage area of the portion where the TCV 23 is provided at a minimum area (hereinafter, “minimum opening VAmin” (solid line in FIG. 2)) and a passage of the portion where the TCV 23 is provided. It changes between the opening degree which maintains an area to the maximum area (henceforth "maximum opening degree VAmax" (two-dot chain line of FIG. 2)). Hereinafter, regarding the TCV opening VA, any opening between the minimum opening VAmin and the maximum opening VAmax is referred to as “intermediate opening VAmid”.

  When the TCV opening VA is at the minimum opening VAmin, the passage area of the intake passage formed between the wall surface of the intake pipe 21 and the peripheral edge of the valve tip 23T has a minimum size, and the tumble flow in the combustion chamber 11 The degree of promoting the occurrence of is the largest. As the TCV opening VA changes from the minimum opening VAmin side to the maximum opening VAmax side at the intermediate opening VAmid, the intake air formed between the wall surface of the intake pipe 21 and the peripheral edge of the valve tip 23T. The passage area of the passage gradually increases, and the degree of promoting the generation of a tumble flow in the combustion chamber 11 gradually decreases. When the TCV opening VA is at the maximum opening VAmax, the passage area of the intake passage formed between the wall surface of the intake pipe 21 and the peripheral edge of the valve tip 23T has the maximum size. The degree of promoting the occurrence of tumble flow is the smallest.

  When the TCV opening VA is at the maximum opening VAmax, the entire valve body 23B is accommodated in the accommodating portion 21A provided in the intake pipe 21. Further, the TCV shaft 23A is provided in such a manner that it is previously accommodated in the accommodating portion 21A. That is, the entire opening degree VAmax of the TCV 23 is in a state of being accommodated in the accommodating portion 21A. Since the accommodating portion 21A is formed so as to protrude radially outward from the intake passage, the TCV 23 accommodated in the accommodating portion 21A substantially forms the wall surface of the intake pipe 21, thereby The resistance of the TCV 23 is kept sufficiently small.

  Here, in the intake pipe 21, the passage area of the portion of the intake pipe 21 (hereinafter referred to as “throttle portion 21 </ b> E”) whose passage area is changed by the TCV 23 is maintained at the next size according to the TCV opening VA. The That is, since the TCV 23 is provided in such a manner that the valve tip 23T is located downstream of the TCV shaft 23A, when the TCV opening VA is at the intermediate opening VAmid or the minimum opening VAmin, The passage area is maximized on the upstream side (TCV shaft 23A side). In the throttle portion 21E, the passage area gradually decreases from the upstream side toward the downstream side, and the passage area is minimized on the most downstream side (the valve tip portion 23T side of the TCV 23) of the throttle portion 21E. When the TCV opening VA is at the maximum opening VAmax, the entire TCV 23 is accommodated in the accommodating portion 21A of the intake pipe 21, so that the passage area is substantially constant in the throttle portion 21E.

  Since the introduction portion 44 of the EGR device 40 is provided at a position closest to the valve tip portion 23T of the TCV 23 at the minimum opening VAmin, the passage area on the intake passage side of the introduction portion 44 corresponds to the TCV opening VA. Changed. That is, the TCV 23 is located at a position where the peripheral edge of the valve tip 23T as the proximity portion is closest to the introduction portion 44 at the minimum opening VAmin, thereby forming a throttle on the intake passage side of the introduction portion 44. This throttle corresponds to the portion of the throttle portion 21E formed by the TCV 23 in the intake pipe 21 that has the smallest passage area, and its pressure is higher than the pressure on the upstream side and the downstream side of the throttle portion in the intake passage. Lower.

  As described above, in the internal combustion engine 1, when the TCV 23 is at the minimum opening VAmin, the intake pipe 21 is maintained so that the peripheral edge of the valve tip 23T and the introduction portion 44 are kept as close as possible to each other. The relationship between the attachment position of the TCV 23 and the formation position of the introduction portion 44 is set. When the TCV 23 is at the minimum opening VAmin, an effect on the amount of EGR gas (hereinafter referred to as “EGR gas amount”) flowing into the combustion chamber 21 and the combustion chamber, which changes as the TCV opening VA changes, That is, the action of increasing the amount of EGR gas from the introduction portion 44 to the intake passage is maintained in a state where it is maximized.

  Here, the details of the passage area and pressure in the above-described throttle portion 21E and the vicinity thereof will be described. In the following, the passage surface having the smallest passage area due to the valve tip 23T will be referred to as “throttle section R1,” the pressure in the throttle section R1 will be referred to as “throttle pressure P1,” and the passage area will be referred to as “throttle area A1”. . Further, the passage surface in the region upstream of the TCV shaft 23A is defined as “upstream section R2,” the pressure in the upstream section R2 is defined as “upstream pressure P2,” and the passage area is defined as “upstream area A2.” The passage surface in the region downstream of the throttle section R1 is defined as a “downstream section R3”, the pressure in the downstream section R3 is defined as “downstream pressure P3”, and the passage area is defined as a “downstream area A3”.

  When the TCV 23 is at the intermediate opening VAmid or the minimum opening VAmin, the relationship between the passage areas is “A2> A1” and “A3> A1”. At this time, due to the Venturi effect, the relationship between the pressures of the respective parts becomes “P2> P1” and “P3> P1”. Further, since the negative pressure from the combustion chamber 11 is generated in the region R3 on the combustion chamber 11 side and is downstream in the direction of the intake air flow, if there is no difference between the passage areas A1 and A2, "P2> P3" A relationship will be established. Therefore, when the TCV 23 moves to the closing side, the relationship “P2> P3> P1” is established.

  Since A1 and P1 vary depending on the value of the TCV opening VA, when “A11 <A12” is established, let us consider R11 (P11) and R12 (P12) corresponding to A11 and A12, respectively. “A11 <A12” indicates that A11 is smaller than the TCV opening VA when the TCV opening VA is A12. At this time, the relationship of “P11 <P12” is established by the Venturi effect. That is, when the TCV 23 moves to the maximum opening VAmax side, the pressure in the same portion of the intake pipe 21 decreases.

  When the pressure of the intake pipe 21 in a portion communicating with the EGR gas introduction portion 44 is low (the negative pressure of the intake pipe 21 is large), the EGR gas sent by the EGR pipe 41 is easily introduced into the intake pipe 21. That is, when the TCV 23 moves to the closing side, a large amount of EGR gas can be introduced.

  On the other hand, when the EGR gas is not introduced, the pressure of P1 can be made equal to P2 by fully opening the TCV 23, and the introduction of the EGR gas can be suppressed. Further, at this time, it is possible to prevent the pressure loss of the intake air flow. Therefore, the amount of EGR gas flowing into the intake pipe 21 can also be controlled by changing the opening of the TCV 23. In particular, when the throttle opening degree TA decreases rapidly, the intake air amount GA also decreases rapidly. When it is requested to stop the introduction of the EGR gas into the intake pipe or to reduce the introduction amount in order to suppress the increase in the EGR rate that accompanies this, this request is made by driving the EGR valve 42 to the valve closing side. Will be executed.

  By the way, when the throttle valve 22 is suddenly closed, the intake air amount GA introduced into the combustion chamber 11 rapidly decreases as described above. On the other hand, EGR gas that has already flowed into the downstream side 41B of the EGR pipe 41 rather than the EGR valve 42 that closes in conjunction with the throttle valve 22 of the EGR pipe 41 cannot be blocked by the EGR valve 42. Further, since the time required for the EGR valve 42 to be completely closed is longer than the time required for the throttle valve 22 to be completely closed, the EGR gas remains in the intake pipe even after the time difference and the intake air amount GA have decreased. Inflow to 21 will continue. However, when the TCV 23 is opened at the same time, that is, a situation where the pressure of the intake pipe 21 of the throttle portion 21E is relatively high is created, the introduction of the EGR gas into the intake pipe 21 is hindered. It is possible to achieve a high EGR rate.

With reference to FIG. 3, the “TCV opening changing process”, which is a specific processing procedure when controlling the TCV 23 described above, will be described.
When the driver performs an operation that suddenly becomes “minimum” from the state where the accelerator operation amount AP is “large”, the throttle valve 22 changes the throttle opening degree TA from “large” to “minimum”. A quick closing request will be made. If it is not determined in step S11 that the throttle valve 22 is rapidly closed, this process ends.

  If it is determined in step S11 that the throttle valve 22 is suddenly closed, the process proceeds to step S12 and the EGR valve 42 is closed. Further, in step S13, the TCV 23 is opened to the maximum opening VAmax, and the TCV 23 is maintained at the maximum opening VAmax. When the opening degree of the TCV 23 has already reached the maximum opening degree VAmax, an operation for maintaining the same state is performed.

  Next, in step S14, it is determined whether or not the EGR rate is stable. As a criterion for determining whether or not the EGR rate is stable, for example, whether or not a certain time elapse condition sufficient for stabilizing the EGR rate based on an experimental value or a measured value of an oxygen sensor that measures the oxygen concentration in exhaust gas satisfies a certain condition Or the like. If it is determined that the condition for stabilizing the EGR rate is not satisfied, the process returns to step S13 and the opening degree of the TCV 23 is maintained. If it is determined that the EGR rate is stable, the process proceeds to step S15, the maintenance of the opening degree of the TCV 23 is released, and the process ends.

  With reference to FIG. 4, an example of an execution mode of “TCV opening change processing” will be described. In the figure, an internal combustion engine having the same configuration as that of the internal combustion engine 1 of the present embodiment is assumed except that the “TCV opening degree changing process” shown in FIG. 3 is not executed. Changes in the amount of EGR gas and the EGR rate in the engine (hereinafter referred to as “virtual engine”) are also shown by broken lines.

  If the accelerator operation amount AP changes suddenly from the predetermined depression amount to the minimum depression amount (deceleration of the accelerator pedal 24) at time t11, the target value of the throttle opening degree TA is based on this change in the throttle control. A new target opening degree TAT (here, “minimum opening degree TAL”) corresponding to the pedal operation is set as (hereinafter “target opening degree TAT”). Then, the closing operation of the throttle valve 22 is started to change the actual throttle opening degree TA from the opening degree at that time to the minimum opening degree TAL. The operation described below is the same when the throttle opening degree TA decreases as the accelerator pedal 24 is operated without newly setting the target opening degree TAT.

  At this time, in the EGR control, a request for reducing the EGR gas amount is set based on the request for changing the throttle opening TA, and the target value of the EGR opening EA (hereinafter referred to as “target opening” is set in response to the setting of this request. A new target opening degree EAT (here, “minimum opening degree EAL”) corresponding to the throttle operation is set as “EAT”). Then, the closing operation of the EGR valve 42 is started so as to change the actual EGR opening degree EA from the opening degree at that time to the minimum opening degree EAL.

  Here, since the responsiveness of the EGR valve 42 is lower than that of the throttle valve 22, the throttle opening TA starts to change quickly toward the target opening TAT at time t11, whereas the EGR opening EA is The change to the target opening degree EAT is started slightly later than the throttle opening degree TA. In addition, in addition to the difference in opening start timing, the throttle valve opening speed of the throttle valve 22 is larger than the valve closing speed of the EGR valve 42, so that the throttle opening TA is reduced to the minimum opening TAL. After reaching, a relatively long time is required until the EGR opening degree EA reaches the minimum opening degree EAL.

  Now, according to the internal combustion engine 1 of the present embodiment, the valve opening operation of the TCV 23 is started in the TCV control in accordance with the closing operation of the EGR valve 42 at time t12. That is, based on the request to decrease the EGR gas amount and the TCV opening VA being at the minimum opening VAmin, the TCV 23 is driven to the valve opening side so as to make the TCV opening VA the maximum opening VAmax.

  As the TCV opening VA changes from the minimum opening VAmin to the maximum opening VAmax, that is, as the valve tip 23T of the TCV 23 moves away from the introduction part 44 of the EGR device 40, the intake passage of the introduction part 44 The pressure on the side is larger than the pressure when the TCV opening VA is at the minimum opening VAmin (the negative pressure in the intake pipe 21 is reduced). Thereby, when the EGR gas amount after the valve opening operation of the TCV 23 is compared with that of the virtual engine, the EGR opening degree EA is the same, but shows a smaller value than that of the virtual engine. Further, in the virtual engine, the EGR gas amount temporarily increases after the start of the closing operation of the EGR valve 42, and the EGR rate also tends to increase along with this, so that the EGR rate exceeds the misfire limit. This increases the possibility that the combustion state becomes unstable.

  On the other hand, according to the internal combustion engine 1 of the present embodiment, the pressure on the intake passage side of the introduction portion 44 increases through the valve opening operation of the TCV 23 after the start of the valve closing operation of the EGR valve 42. Therefore, the amount of EGR gas is reduced. The degree of decrease exceeds that of the virtual institution, and the degree of increase in the EGR rate is below that of the virtual institution. In other words, the degree of fluctuation of the EGR rate based on the required value is maintained at a relatively small degree in the internal combustion engine 1, whereas the virtual engine shows a tendency to fluctuate to a level exceeding the misfire limit. Furthermore, after the start of the closing operation of the EGR valve 42, a comparison is made between the internal combustion engine 1 and the virtual engine for the period until each of the EGR gas amount and the EGR rate is stabilized at the required value. In both cases, the former tends to be shorter.

  The maximum opening VAmax of the TCV opening VA is maintained until the EGR rate is stabilized. However, depending on the operating state of the internal combustion engine, for example, the throttle opening TA increases and the intake air amount GA increases again. Continue until Alternatively, after the EGR rate is stabilized, the maximum opening degree VAmax of the TCV opening degree VA is canceled at time t13 without waiting for the increase in the intake air amount, and any one of the intermediate opening degree VAmid and the minimum opening degree VAmin is opened. It is also possible to change to (dotted line in the figure).

[Effect of the embodiment]
As described above in detail, according to the intake device for an internal combustion engine of the present embodiment, the following effects can be obtained.

  (1) In the intake device of the present embodiment, when the TCV 23 is at the maximum opening VAmax, a low pressure part is formed on the intake passage side of the introduction part 44 of the EGR pipe 41, so the EGR pipe 41 is different from this. It becomes possible to increase the amount of EGR gas more than when it is at the opening degree. That is, because of the venturi effect, the pressure at the portion on the intake passage side of the introduction portion 44 is lower than the pressure at the intake upstream side and the intake downstream side, so that the flow velocity of the intake air passing through the portion increases. The amount of exhaust gas circulating from the EGR pipe 41 to the intake passage increases.

  As described above, the EGR gas amount can be increased by the operation of the TCV 23. However, when the EGR gas amount is requested to decrease and the TCV 23 is at the maximum opening VAmax, that is, when the throttle valve 22 is suddenly closed. Although there is a demand for reducing the EGR gas amount based on the above, when the EGR gas amount increasing action by the TCV 23 is maximized, the EGR gas amount can be sufficiently reduced. There is a concern that it may lead to deterioration of the combustion state due to not being performed.

  In view of this point, the intake device of the present embodiment performs the separation control of the TCV 23 when there is a request to reduce the EGR gas amount and the TCV 23 is at the maximum opening VAmax. That is, since the increase effect of the EGR gas amount by the TCV 23 is reduced, it is possible to suppress the deterioration of the combustion state due to the exhaust gas recirculated to the intake pipe 21. Note that the maximum opening VAmax of the TCV 23 at this time is not only the maximum opening VAmax but also the intermediate opening VAmid that forms a substantially similar low pressure state in a portion on the intake passage side of the introduction portion 44. It can also be included.

  (2) In the intake device of the present embodiment, according to the present invention, when the TCV 23 is driven to the maximum in the direction of reducing the vortex, the intake air flowing through the intake passage is not hindered by the TCV 23. That is, the pressure loss due to the TCV 23 in the same state can be reduced.

  (3) In general, since the responsiveness of the EGR valve 42 is low, even if the EGR valve 42 is driven to the valve closing side based on a request to reduce the EGR gas amount, the EGR gas amount decreases to a target position. It takes a relatively long time. In this regard, according to the intake device of the present embodiment, the separation control is performed on the TCV 23 having higher response than the EGR valve 42 in accordance with the operation of the EGR valve 42 on the valve closing side, and therefore only the EGR valve 42 is used. Compared with the case where the EGR gas amount is reduced through the operation, the EGR gas amount can be rapidly reduced.

  (4) In the intake device of the present embodiment, the EGR gas amount increasing action by the TCV 23 is enhanced, so that the EGR gas amount increases more than before the request for increasing the EGR gas amount occurs under the same other conditions. This makes it possible to respond to the request more quickly.

  (5) In the intake device of the present embodiment, the ratio of the EGR gas amount to the intake air amount is increased by maintaining the opening of the TCV 23 until the ratio of the EGR gas amount to the intake air amount shows a stable value. It becomes possible to suppress suitably.

  (6) In the intake device of the present embodiment, when an EGR gas amount reduction request is generated as the throttle valve 22 is suddenly closed, the EGR valve 42 is driven to the close side and the TCV 23 is driven to the open side, and the EGR gas is suitably used. Try to reduce the amount. When the intake air amount decreases, if the decrease in the EGR gas amount flowing into the intake pipe 21 is delayed from the decrease in the intake air amount, the ratio of the EGR gas amount will rise temporarily. In particular, when the throttle valve 22 is suddenly closed, it is considered that this ratio is likely to increase. Therefore, by driving the TCV 23 to the open side when there is a decrease in the EGR gas amount due to the sudden closing of the intake air amount control valve, the ratio of the EGR gas amount to the intake air amount is temporarily increased even in such a case. Can be suitably suppressed.

(Other embodiments)
The embodiment of the present invention is not limited to the above-described embodiment, and can be carried out, for example, in the following manner.

  In the above embodiment, when the TCV opening VA is at the minimum opening VAmin, the relationship between the TCV 23 and the introducing portion 44 is set so that the periphery of the TCV 23 is as close as possible to the introducing portion 44. The periphery of the TCV 23 can be made as close as possible to the introduction portion 44 at an opening other than the opening VAmin. In this case, since the low pressure portion is formed between the peripheral edge of the TCV 23 and the introduction portion at the same opening, when the TCV 23 is at the same opening, the opening is different from this. It becomes possible to increase the amount of EGR gas more than sometimes.

  In the above embodiment, the introduction portion 44 of the EGR device 40 is formed on the wall surface of the intake pipe 21 that faces the housing portion 21A, but the formation position of the introduction portion 44 is not limited to this. For example, as shown in FIG. 5, for the wall surface of the intake pipe 21 that does not face the housing portion 21 </ b> A, that is, the wall surface between the wall portion that faces the housing portion 21 </ b> A and the housing portion 21 </ b> A, 46 can also be formed.

  In the above embodiment, the valve body 23B of the TCV 23 is assumed to have a shape corresponding to the shape of the inner periphery of the intake pipe 21, but a TCV 25 as shown in FIG. 6 may be used instead. The TCV 25 includes a TCV shaft 26A installed on the wall surface of the intake pipe 21, and a TCV auxiliary shaft 27A between the first valve body portion 26B and the second valve body portion 27B extending from the TCV shaft 26A. The TCV shaft 26A and the TCV auxiliary shaft 27A are provided with actuators, respectively, so that they can be driven differently.

  Further, when the TCV 25 is at the minimum opening VAmin, the attachment position of the TCV 25 in the intake pipe 21 and the introduction portion 44 are maintained so that a part of the second valve body portion 27B and the introduction portion 44 are kept as close as possible. The relationship with the formation position is set. That is, at the minimum opening VAmin, a part of the second valve body portion 27B as the proximity portion is located closest to the introduction portion 44, and thereby the intake passage of the introduction portion 44 is narrowed. In any case, the present invention can be applied to any intake device as long as the intake portion of the EGR gas is set in the intake passage portion where the passage area is narrowed by opening / closing drive of the TCV. .

  In the above embodiment, in the “TCV opening change processing”, the TCV 23 is changed to the maximum opening VAmax when the TCV opening VA is at the minimum opening VAmin. However, the minimum opening VAmin has a range. You can also. That is, with respect to the pressure of the portion on the intake passage side of the introduction portion 44, other pressures in the vicinity of the minimum opening VAmin that maintains the pressure substantially the same as that when the TCV opening VA is set to the minimum opening VAmin. With respect to the opening, it is possible to perform the valve opening operation of the TCV 23 by regarding this as the minimum opening VAmin.

  In the above embodiment, in the “TCV opening change processing”, when the EGR gas amount reduction request is made and the TCV opening VA is at the minimum opening VAmin, the TCV opening VA is changed to the maximum opening VAmax. Although it is configured, it is also possible to set one of the opening degrees of the intermediate opening degree VAmid instead of the maximum opening degree VAmax. In the above-described embodiment, the specific opening (maximum opening VAmax) is used. However, the opening can be variably set within the range of the maximum opening VAmax and the intermediate opening VAmid according to the engine operating state. That is, as the TCV opening VA increases, the effect of decreasing the EGR gas amount increases. Therefore, based on the engine operating condition at that time, the required effect is grasped and the TCV 23 is adjusted accordingly. A valve opening operation can also be performed.

  In the above embodiment, it is assumed that the actuators connected to the TCV shafts 23A of the plurality of TCVs 23 installed in the intake passage leading to the combustion chamber 11 are common. However, for example, it is also possible to control each TCV shaft 23A of one or several TCVs 23 by connecting different actuators.

  In the above embodiment, the interlock control of the EGR valve 42 and the TCV 23 is performed when the throttle valve 22 is suddenly closed. However, this is not limited to when the throttle valve 22 is suddenly closed, and when there is a request to reduce the EGR gas amount. In either case, the same can be implemented. That is, by opening the TCV 23 based on the request for reducing the amount of EGR gas, the amount of EGR gas flowing into the combustion chamber 11 can be reduced in a shorter time than the control by the EGR valve 42 alone. Further, when it is desired to increase the EGR gas amount, the EGR gas amount flowing into the combustion chamber 11 can be increased by closing the TCV 23.

The schematic diagram which shows typically the structure of the internal combustion engine carrying the apparatus about one Embodiment which actualized the intake device of the internal combustion engine of this invention. Sectional drawing which shows the cross-sectional structure about some intake pipes of the embodiment. The flowchart which shows the process sequence about "TCV opening change process" performed in the embodiment. The timing chart which shows an example of the execution aspect about "TCV opening degree change process" of the embodiment. Sectional drawing which shows the partial cross-section of an intake pipe about the modification of the embodiment. Sectional drawing which shows the partial cross-section of an intake pipe about the modification of the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 10 ... Engine main body, 11 ... Combustion chamber, 12 ... Intake valve, 13 ... Exhaust valve, 14 ... Piston, 15 ... Crankshaft, 20 ... Intake device, 21 ... Intake pipe, 21A ... Housing part, 21E ... Throttle part, 22 ... Throttle valve (intake amount control valve), 23 ... TCV (intake flow control valve), 23A, 26A ... TCV shaft, 23B ... Valve body, 23T ... Valve tip (proximity part), 24 ... Accelerator Pedal, 25 ... TCV, 26B ... first valve body part, 27A ... TCV auxiliary shaft, 27B ... second valve body part, 31 ... exhaust pipe, 40 ... EGR device (exhaust gas recirculation device), 41,45 ... EGR pipe ( Exhaust gas recirculation pipe), 42... EGR valve (exhaust gas recirculation valve), 43... Intake part, 44 and 46 .. introduction part (opening part), 50... Control device, 51. ... Throttle position Capacitors, 54 ... air flow meter, 55 ... EGR position sensor.

Claims (9)

An internal combustion engine having an exhaust gas recirculation device that circulates a part of exhaust gas from an exhaust pipe to an intake pipe by an exhaust gas circulation pipe, and controlling the intake air flow provided in the intake pipe to adjust the intake air flow In an intake device for an internal combustion engine comprising a control valve and a control device that controls the control valve,
The intake flow control valve is located at a position where a proximity portion that is a part of the intake flow control valve is closest to an opening portion of the exhaust gas recirculation pipe with respect to the intake pipe, and thereby the intake passage side of the opening portion In this part, a lower pressure part than the intake upstream side and the intake downstream side of the same part is formed,
When there is a request to reduce the exhaust gas flow rate and the intake flow control valve is at the predetermined opening, the control device separates the proximity portion of the intake flow control valve from the opening than before the reduction request is generated. An intake device for an internal combustion engine, wherein separation control is performed to drive the control valve in a direction to be driven. The intake device for an internal combustion engine according to claim 1,
The intake device for an internal combustion engine, wherein the intake flow control valve adjusts a generation mode of a vortex flow in the combustion chamber based on an opening / closing operation thereof. The intake device for an internal combustion engine according to claim 2,
The intake device for an internal combustion engine, wherein the intake flow control valve has an opening when the vortex is driven to the maximum in a direction in which the vortex is increased. The intake device for an internal combustion engine according to claim 2 or 3,
The intake device for an internal combustion engine, wherein the intake flow control valve is housed in a housing portion provided in the intake pipe when driven to the maximum in a direction to reduce the vortex flow. The intake device for an internal combustion engine according to any one of claims 1 to 4,
When there is a request to increase the exhaust gas flow rate, the control device brings the opening of the intake flow control valve closer to the predetermined opening than before the request is generated. In the intake device of the internal combustion engine according to any one of claims 1 to 5,
The exhaust gas recirculation device includes an exhaust gas recirculation valve that is provided in the exhaust gas recirculation pipe and adjusts an exhaust gas recirculation flow rate,
The internal combustion engine intake device according to claim 1, wherein the control device performs the separation control when the exhaust gas recirculation valve operates toward the valve closing side based on a request to reduce the exhaust gas flow rate. The intake device for an internal combustion engine according to claim 6,
The control device performs a prohibition control for prohibiting the opening degree of the intake flow control valve from approaching the predetermined opening degree until the ratio of the exhaust gas flow rate to the intake air amount becomes stable after the separation control is executed. An intake device for an internal combustion engine characterized by the above. The intake device for an internal combustion engine according to claim 7,
After executing the prohibition control, the control device ends the prohibition control based on the fact that the ratio of the exhaust gas flow rate to the intake air amount has become stable, whereby the opening degree of the intake flow control valve is set to the predetermined opening degree. An intake device for an internal combustion engine, characterized in that it is allowed to approach the The intake device for an internal combustion engine according to any one of claims 1 to 8,
The reduction request for the exhaust ring flow rate is caused by the sudden closing of an intake air amount control valve that is provided upstream of the intake air flow control valve of the intake pipe and controls the intake air amount. apparatus.

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