JP2010285937A - Blow-by gas processing device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blow-by gas processing device for melting adhered ice by low-pressure EGR gas to prevent the ice from damaging a compressor blade. <P>SOLUTION: When the operation state of an engine 10 is in a first operation state, an electrical control unit 80 opens a low-pressure EGR valve 63, and recirculates low-pressure EGR gas through a low-pressure EGR passage 61. Further, when an outside air temperature is lower than a predetermined outside air temperature threshold value, and a cooling water temperature is lower than a predetermined cooling water temperature threshold value (i.e., the moisture in a blow-by gas tube 70 is highly possible to freeze), the electrical control unit recirculates the low-pressure EGR gas even if the operation state of the engine is not the first operation state. Hence, the vicinity of a connection portion between the blow-by gas tube and the low-pressure EGR passage is heated, and ice generated in the blow-by gas tube is defrosted and removed. As a result, water turned to ice in the blow-by gas tube is prevented from flowing in a compressor 35a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a blow-by gas processing apparatus used for an internal combustion engine.

  Conventionally, blowby gas processing apparatuses that have been widely employed treat the blowby gas that has leaked from the combustion chamber of the internal combustion engine into the crankcase and the like through the “blowby gas pipe and intake passage” and return it to the combustion chamber.

  One of such conventional blow-by gas processing devices (hereinafter also referred to as “conventional device”) has an outlet of a blow-by gas pipe connected to a low-pressure EGR passage (low-pressure exhaust gas recirculation passage) provided in the low-pressure EGR device. Yes. The low pressure EGR device is a low pressure EGR that is an exhaust passage of an internal combustion engine downstream of a turbocharger provided in the engine and an intake passage of the engine upstream of a compressor of the supercharger. This is a device for communicating with a passage and recirculating a relatively low pressure exhaust gas as a low pressure EGR gas.

  Further, this conventional apparatus is provided with a carbon trap chamber at a connection point between the low pressure EGR passage and the blow-by gas pipe. Thereby, the conventional apparatus mixes “carbon contained in the low-pressure EGR gas” and “oil mist contained in the blow-by gas” in the chamber. As a result, since carbon is adsorbed by the oil mist in the chamber, the carbon is separated from the gas introduced into the intake passage.

JP-A-8-135518

  By the way, in addition to the oil mist described above, the blow-by gas may contain water (particularly including water vapor generated by combustion). The water in this blow-by gas is used when the temperature of the outside air is relatively low, such as when the engine is used in a cold region or in the winter, and immediately after the engine is cold started. Thus, when the engine temperature is relatively low, it may become ice and adhere to the “blow-by gas pipe” and the “connection part between the blow-by gas pipe and the low-pressure EGR passage”.

  However, the conventional apparatus described in Patent Document 1 recirculates the low-pressure EGR gas only when the operating state of the engine is a “predetermined operating state determined by the engine load and the engine speed”. In some cases, the attached ice cannot be melted by the heat of the low-pressure EGR gas. As a result, in the conventional apparatus, the adhering ice may be sucked into the supercharger compressor as it is and may damage the compressor blades.

  The present invention has been made to solve the above problems, and one of its purposes is to change the conditions under which the low-pressure EGR gas is refluxed, thereby melting the ice adhering to the low-pressure EGR gas. Accordingly, it is an object of the present invention to provide a blow-by gas processing apparatus capable of preventing the compressor blades from being damaged by ice.

Specifically, the blow-by gas processing apparatus for an internal combustion engine according to the present invention is:
A supercharger having a "compressor disposed in an intake passage of an internal combustion engine";
An EGR passage connecting the “exhaust passage of the engine” and “the intake passage upstream of the compressor”;
An EGR valve disposed in the EGR passage and changing a cross-sectional area of the EGR passage;
Between the blow-by gas discharge part provided in the main body of the engine and the “predetermined portion of the EGR passage” located on the “downstream side of the EGR valve in the flow of EGR gas flowing in the EGR passage” A blow-by gas pipe to be connected.

  The blow-by gas processing apparatus further includes first reflux means, icing generation condition establishment determination means, and second reflux means.

  Here, the first recirculation means recirculates the EGR gas through the EGR passage by opening the EGR valve when the engine is in the first operation state. In addition, the icing occurrence condition establishment determining means determines whether or not a predetermined condition is established. As will be described later, the predetermined condition may be, for example, a condition that is satisfied when the outside air temperature is equal to or lower than a predetermined temperature, or may be a condition that is satisfied when the engine temperature is equal to or lower than the predetermined temperature. . In other words, the predetermined condition is determined in advance when the predetermined condition is satisfied, and the possibility that the moisture in the blow-by gas pipe is frozen is higher than when the predetermined condition is not satisfied. It is a condition.

  Furthermore, when the second reflux means determines that the predetermined condition is satisfied by the icing occurrence condition establishment determination means, even if the engine is in a second operation state different from the first operation state, The EGR gas is recirculated through the EGR passage by opening the EGR valve.

  According to the present invention, when it is determined that the predetermined condition is satisfied, that is, the possibility that the water in the blow-by gas pipe is frozen is increased, the engine operating state is other than the first operating state, that is, “originally Even in the “second operating state in which the EGR gas is not recirculated”, the EGR valve is opened by the second recirculation means, and the EGR gas is recirculated. Therefore, when there is a high possibility that the water in the blow-by gas pipe is frozen, the EGR gas flows to the connection point between the blow-by gas pipe and the EGR passage (that is, the outlet of the blow-by gas pipe). Therefore, the possibility of water freezing and adhering to the vicinity of the outlet of the blow-by gas pipe can be reduced. Further, even when ice adheres to the blow-by gas pipe, the ice is heated and melted by the EGR gas in the vicinity of the outlet of the blow-by gas pipe. As a result, it is possible to prevent “ice is sucked into the supercharger and the compressor blades are damaged by the ice”.

  By the way, as described above, when the temperature of the outside air acquired by the outside air temperature acquisition unit is not more than a predetermined outside air temperature threshold, for example, not more than zero degrees Celsius, compared to the case where the temperature of the outside air is higher than the outside air temperature threshold, The possibility that the water in the blow-by gas pipe freezes increases.

  Therefore, the icing condition establishment determination means includes an outside air temperature acquisition means for acquiring the temperature of the outside air, and the predetermined condition is satisfied when the outside air temperature acquired by the outside air temperature acquisition means is equal to or less than an outside air temperature threshold value. Suitably configured to determine.

  Further, the icing condition establishment determining means includes an engine temperature acquisition means for acquiring the temperature of the engine, and the predetermined condition when the engine temperature acquired by the engine temperature acquisition means is equal to or lower than a predetermined engine temperature threshold value. It can also be configured to determine that is established.

  When the engine temperature acquired by the engine temperature acquisition means is equal to or lower than the engine temperature threshold, it is considered that the engine is not sufficiently warmed up. Therefore, when the outside air temperature is low, “the amount of heat taken away from the blow-by gas pipe” by the outside air may exceed “the amount of heat given to the blow-by gas pipe” by the exhaust from the combustion chamber and / or the engine main body. It can be said that the moisture in the gas may freeze. On the other hand, when the internal combustion engine is sufficiently warmed up, such as when the vehicle is operating for a certain period of time, such as when traveling in a high load region, the amount of heat taken away from the blowby gas tube It can be said that the amount of heat applied exceeds the possibility that the moisture in the blow-by gas freezes.

  In the present invention, the icing condition establishment determination means includes vehicle speed acquisition means for acquiring a traveling speed of a vehicle on which the engine is mounted, and the traveling speed acquired by the vehicle speed acquisition means is higher than the first threshold speed. It may be configured to determine that the predetermined condition is satisfied when the traveling speed is lower or the second threshold speed is higher than the first threshold speed.

  In general, the engine load varies depending on the traveling speed of the vehicle. When the traveling speed of the vehicle is equal to or lower than the first threshold speed, for example, when the engine is in an idle operation state, such as when the vehicle is stopped, the engine load is low and the engine temperature is not easily increased. Therefore, the temperature of the blow-by gas discharged from the engine main body is also low, so the amount of heat given to the blow-by gas pipe is reduced, and the possibility that the water in the blow-by gas freezes increases. On the other hand, when the traveling speed of the vehicle is equal to or higher than the second threshold speed, for example, when the vehicle is traveling at a high speed, if the traveling speed is high, the influence of traveling wind received by the internal combustion engine increases. As the influence of the traveling wind increases, the blow-by gas pipe is easily deprived of heat by the outside air, so that the possibility that the water in the blow-by gas freezes increases. The determination based on the traveling speed may be performed in addition to the determination based on the outside air temperature and / or the determination based on the engine temperature.

It is a schematic block diagram of the blowby gas processing apparatus which concerns on embodiment of this invention. 3 is a flowchart showing a routine executed by a CPU of the electric control device shown in FIG. 1 in the first embodiment. In 2nd Embodiment, it is the flowchart which showed the routine which CPU of the electric control apparatus shown in FIG. 1 performs.

(First embodiment)
Embodiments according to the present invention will be described below with reference to the drawings. The blow-by gas processing apparatus according to the first embodiment is applied to the internal combustion engine (four-cylinder diesel engine) 10 shown in FIG. The engine 10 includes an engine body 20, an intake system 30, an exhaust system 40, a high pressure EGR device 50, a low pressure EGR device 60, and a blow-by gas pipe 70. Further, the blow-by gas processing device includes an electric control device 80.

  The engine body 20 includes four combustion chambers configured from “cylinder, lower surface of head, upper surface of piston, and the like” (not shown), and fuel injection valves for directly injecting fuel into each combustion chamber.

  The intake system 30 includes an intake passage 31 formed of an intake pipe. The intake passage 31 is connected to a collective portion of “an intake manifold 32 having branches connected to each combustion chamber”. It is also expressed that the intake passage 31 and the intake manifold 32 together constitute an “intake passage”. The intake system 30 includes an “air cleaner 33, a first throttle valve (intake throttle valve) 34, a compressor 35a of the supercharger 35 disposed in the intake passage 31 from the upstream side toward the downstream side in the flow of air (outside air). , An intercooler 36 and a second throttle valve (throttle valve) 37 ". The first throttle valve 34 and the second throttle valve 37 rotate in response to an instruction signal from the electric control device 80 so that the flow passage cross-sectional area of the intake passage 31 can be changed.

  The exhaust system 40 includes an exhaust passage 41 composed of an exhaust pipe. The exhaust passage 41 is connected to a collective portion of “exhaust manifold 42 having branches connected to each combustion chamber”. It is also expressed that the exhaust passage 41 and the exhaust manifold 42 together constitute an “exhaust passage”. The exhaust system 40 is arranged in the exhaust passage 41 from the upstream side toward the downstream side in the flow of exhaust “the turbine 35b of the supercharger 35, the exhaust purification catalyst 43, and the third throttle valve (exhaust throttle valve) 44”. Is provided. The third throttle valve 44 rotates in response to an instruction signal from the electric control device 80 and can change the flow passage cross-sectional area of the exhaust passage 41.

  The high-pressure EGR device 50 includes a high-pressure EGR passage 51 connected to the collecting portion of the exhaust manifold 42 and the collecting portion of the intake manifold 32. The EGR gas flowing through the high pressure EGR passage 51 is referred to as “high pressure EGR gas”. The high-pressure EGR device 50 includes a “high-pressure EGR cooler 52 and a high-pressure EGR valve 53” disposed in the high-pressure EGR passage 51 from the upstream side toward the downstream side in the direction in which the high-pressure EGR gas flows. The high-pressure EGR valve 53 rotates in response to an instruction signal from the electric control device 80 and can change the flow path cross-sectional area of the high-pressure EGR passage 51.

  When the engine operating state is a predetermined low load region in which the pressure in the intake passage 31 downstream from the compressor 35a is low, the high pressure EGR passage 50 receives the high pressure EGR passage according to an instruction signal from the electric control device 80. The high pressure EGR valve 53 of 51 is opened, and the high pressure EGR gas is introduced to the downstream side of the intake system compressor 35 a through the high pressure EGR passage 51, for example, into the intake manifold 32. By introducing this high-pressure EGR gas, an action of suppressing generation of NOx and an action of reducing pumping loss can be obtained. Furthermore, the relatively high-temperature high-pressure EGR gas before passing through the exhaust purification catalyst 43 in the exhaust passage 41 is introduced into the combustion chamber of the engine body 20, so that combustion at a low load is stabilized. On the other hand, in a predetermined high load region where the pressure in the intake passage 31 downstream from the compressor 35a is high, generally a pressure difference between the intake system and the exhaust system hardly occurs, or the pressure on the intake system side becomes high. The high-pressure EGR gas is difficult to recirculate, and the high-pressure EGR device 60 cannot be operated.

  The low pressure EGR device 60 includes an exhaust passage 41 between the “exhaust purification catalyst 43 and the third throttle valve 44” disposed in the exhaust passage 41, and a “first throttle valve 34” disposed in the intake passage 31. A low pressure EGR passage 61 connecting the intake passage 31 between the compressor 35a and the compressor 35a is provided. The EGR gas flowing through the low pressure EGR passage 61 is referred to as “low pressure EGR gas”. The low-pressure EGR device 60 includes a “low-pressure EGR cooler 62 and a low-pressure EGR valve 63” disposed in the low-pressure EGR passage 61 from the upstream side toward the downstream side in the direction in which the low-pressure EGR gas flows. Further, the low pressure EGR passage 61 includes a bypass passage 64 that bypasses the low pressure EGR cooler 62 and a bypass valve 65. The low pressure EGR valve 63 and the bypass valve 65 rotate in response to an instruction signal from the electric control device 80, and can change the flow path cross-sectional areas of the low pressure EGR passage 61 and the bypass passage 64, respectively. In the present specification, the low pressure EGR valve 63 is also simply referred to as an “EGR valve”.

  One end of the blow-by gas pipe 70 is connected to the blow-by gas discharge part of the engine body 20, and the other end is connected to the low-pressure EGR passage 61 downstream from the low-pressure EGR valve 63 in the direction in which the low-pressure EGR gas flows. Yes. The blow-by gas discharged from the engine body 20, that is, the crankcase and the cylinder head portion is burned by being again introduced into the combustion chamber through the blow-by gas pipe 70, a part of the low-pressure EGR passage 61 and the intake passage 31. It is processed.

  When the engine operating state is in the high load region (when the engine operating state determined by the engine load and the engine speed is in the first operating state), the low pressure EGR device 60 is instructed by the electric control device 80. In response to the signal, the low pressure EGR valve 63 is opened, and the low pressure EGR gas is introduced into the intake passage 31 through the low pressure EGR passage 61. At this time, the pressure in the portion between the intake throttle valve 34 and the compressor 35a is low even in a load region where the pressure in the intake passage 31 downstream of the compressor 35a increases and it is difficult to introduce the high-pressure EGR gas downstream of the compressor 35a. Therefore, the low pressure EGR gas can be introduced into this portion. On the other hand, when the operating state of the engine is in a predetermined low load region, if the low-pressure EGR gas having a relatively low temperature is recirculated to the engine, the effect of stabilizing the combustion by the high-pressure EGR gas is impaired. Cannot be operated.

  The blow-by gas processing apparatus further includes an intake air temperature sensor 81, a cooling water temperature sensor 82, an engine rotation speed sensor 83, a vehicle speed sensor 84, and an accelerator pedal operation amount sensor 85.

  The intake air temperature sensor 81 is disposed between the air cleaner 33 and the first throttle valve 34 in the intake passage 31. The intake air temperature sensor 81 acquires the temperature THA of the air (outside air) flowing into the intake passage 31, and corresponds to the outside air temperature acquisition means in the present invention.

  The cooling water temperature sensor 82 is disposed in a water jacket (not shown) formed in the engine body 20 and acquires the temperature THW of the cooling water passing through the water jacket. The coolant temperature sensor 82 corresponds to the engine temperature acquisition means in the present invention.

  The engine rotation speed sensor 83 detects the rotation of a crankshaft (not shown) of the engine body 20 and acquires the engine rotation speed NE.

  The accelerator pedal operation amount sensor 85 detects the operation amount of the accelerator pedal 85 and acquires the accelerator pedal operation amount Accp.

  The vehicle speed sensor 84 acquires the traveling speed V of the vehicle on which the engine 10 is mounted. The vehicle speed sensor 84 corresponds to vehicle speed acquisition means in the present invention.

  The electric control device 80 includes a digital computer, and includes a ROM (Read Only Memory), a RAM (Random Access Memory), a CPU (Central Processing Unit), and an interface that are connected to each other via a bidirectional bus. The CPU of the electric control device 80 is connected to the sensors 81 to 85 through an interface. The CPU inputs signals from these sensors. Further, the CPU is connected to “the first throttle valve 34, the second throttle valve 37, the third throttle valve 44, the high pressure EGR valve 53, the low pressure EGR valve 63, the bypass valve 65” and the like through the interface. An instruction signal is transmitted.

  Next, the operation of this blow-by gas processing apparatus will be described with reference to FIG.

  The CPU of the electric control device 80 executes the “low pressure EGR control routine” shown by the flowchart in FIG. 2 every time a predetermined time elapses. Accordingly, when the predetermined timing is reached, the CPU starts the process from step S200 of FIG. 2 and proceeds to step S210, where the outside air temperature THA acquired from the intake air temperature sensor 81 is a predetermined outside air temperature threshold T1 (for example, T1 = 0 ° C.). ) Is determined.

  Now, description will be made on the assumption that the driver starts the engine when the outside air temperature is a normal temperature (excluding winter season) that is equal to or higher than a predetermined outside air temperature threshold T1. According to this assumption, the outside air temperature THA is not less than a predetermined outside air temperature threshold T1. Accordingly, the CPU makes a “No” determination at step S210 to proceed to step S220 to execute “low pressure EGR normal control”. That is, when the outside air temperature THA acquired by the intake air temperature sensor 81 is higher than the predetermined outside air temperature threshold value T1, the CPU determines that the possibility that the water in the blow-by gas is frozen is low, and the engine 10 has the first described above. The low pressure EGR gas is recirculated when in the operating state. The process of “low pressure EGR normal control” in step S220 realizes the function of the first reflux means of the present invention.

  Next, description will be made on the assumption that the driver starts the engine when the outside air temperature THA is lower than a predetermined outside air temperature threshold T1 (for example, in a cold region and in winter). According to this assumption, the outside air temperature THA is less than a predetermined outside air temperature threshold T1. Therefore, the CPU makes a “Yes” determination at step S210 to proceed to step S230.

  In step S230, the CPU determines whether or not the cooling water temperature THW acquired from the detection value of the cooling water temperature sensor 82 is less than a predetermined cooling water temperature threshold T2 (for example, T2 = 30 ° C.).

  According to the above assumption that the engine is started in a state where the outside air temperature THA is lower than the outside air temperature threshold T1, the cooling water temperature THW is usually lower than the cooling water temperature threshold T2. Therefore, in this case, the CPU makes a “Yes” determination at step S230 to proceed to step S240 to perform “blow-by gas icing prevention control”. That is, when the cooling water temperature THW acquired by the cooling water temperature sensor 82 is lower than the predetermined cooling water temperature threshold T2, the CPU determines that the water in the blow-by gas is likely to freeze, Preventive control ”is executed.

  Specifically, in step S240, the CPU is not only when the engine operating state is in the first operating state, but also when the engine operating state is not the first operating state (other than the first operating state). (Even in the second operating state), the low pressure EGR valve 63 is opened, the first throttle valve 34 and the second throttle valve 44 are closed, and the low pressure EGR gas is recirculated. The processing of “blow-by gas freezing prevention control” in step S240 realizes the function of the second reflux means of the present invention.

  Further, the CPU causes the low pressure EGR gas to pass through the bypass passage 64 by opening the bypass valve 65 when the low pressure EGR gas is recirculated through the low pressure EGR passage 61 in the “blow-by gas icing prevention control” in step S240. Thereby, since the low pressure EGR gas is not excessively cooled by the low pressure EGR cooler 62, the higher temperature low pressure EGR gas can be recirculated. The above process is continued as long as the outside air temperature THA is lower than the outside air temperature threshold T1 and the cooling water temperature THW is lower than the cooling water temperature threshold T2.

  Thereafter, when the operation of the engine is continued, the cooling water temperature THW becomes equal to or higher than the cooling water temperature threshold T2. In this case, when the CPU proceeds to step S230, the CPU makes a “No” determination at step S230 to proceed to step S220. As a result, “low pressure EGR normal control” is executed.

  Further, when the outside air temperature THA changes to the outside air temperature threshold value T1 or more during the operation of the engine 10, the CPU makes a “No” determination at step S210, proceeds to step S220, and executes “low pressure EGR normal control”. . The above is the operation of the blow-by gas processing apparatus according to the first embodiment.

(Second Embodiment)
Next, a blow-by gas processing apparatus (hereinafter also referred to as “second processing apparatus”) according to a second embodiment of the present invention will be described. In the second processing apparatus, the second condition is that the traveling speed V is lower than the first threshold speed V1 and the traveling speed V is higher than the first threshold speed V1. It is different from the blow-by gas processing apparatus according to the first embodiment only in that a threshold speed V2 or higher is added. Therefore, hereinafter, this difference will be mainly described.

  The CPU of the second processing device executes a “low pressure EGR control routine” shown by a flowchart in FIG. 3 every time a predetermined time elapses. In FIG. 3, steps for performing the same processing as the steps shown in FIG. 2 are denoted by the same reference numerals as those assigned to such steps in FIG. 2. Detailed description of these steps will be omitted as appropriate.

  Now, it is assumed that when the outside air temperature THA is lower than the outside air temperature threshold T1 and the cooling water temperature THW is lower than the predetermined cooling water temperature threshold T2, it is immediately after the vehicle equipped with the engine 10 is started.

  On the other hand, the CPU starts the process from step S300 in FIG. 3 at a predetermined timing and proceeds to step S210. According to the above-described assumption, the outside air temperature THA is lower than the outside air temperature threshold T1. Therefore, the CPU makes a “Yes” determination at step S210 to proceed to step S230. Further, according to the above-described assumption, the coolant temperature THW is lower than a predetermined coolant temperature threshold T2. Therefore, the CPU makes a “Yes” determination at step S230 to proceed to step S310.

  In step S310, the CPU determines that the “traveling speed V acquired from the vehicle speed sensor 84” is less than the “first threshold speed V1 (for example, V1 = 30 km / h)” or the “second threshold speed V2 (however, V2> V1, V2 = 90 km / h) ”or more.

  According to the above-mentioned assumption, since the current time is immediately after the vehicle starts, the traveling speed V is lower than the first threshold speed V1. Accordingly, the CPU makes a “Yes” determination at step S310 to proceed to step S240, and executes the “blow-by gas icing prevention control” described above.

  Thereafter, when the traveling speed V becomes equal to or higher than the first threshold speed V1, the CPU makes a “No” determination at step S310 to proceed to step S220. Therefore, in this case, the CPU executes the above-described “low pressure EGR normal control”.

  Further, when the operation is continued and the traveling speed V becomes equal to or higher than the second threshold speed V2, the CPU determines “Yes” in step S410 and proceeds to step S240. Therefore, in this case, the CPU executes the above-described “blow-by gas freezing prevention control”.

Thus, the freezing generation conditions employed by the second processing apparatus are:
(Condition 1) The outside air temperature THA is lower than the outside air temperature threshold T1,
(Condition 2) The cooling water temperature THW is lower than a predetermined cooling water temperature threshold T2, and
(Condition 3) The traveling speed V is lower than the first threshold speed V1 or greater than or equal to the second threshold speed V2.
It is satisfied when all the conditions are satisfied.

  The condition 3 is added for the following reason. That is, when the traveling speed V is lower than the first threshold speed V1, the engine load is generally low, and therefore the engine temperature is difficult to increase. Therefore, since the blow-by gas temperature discharged from the engine body 20 is also low, the amount of heat given to the blow-by gas pipe 70 is reduced, and the possibility that the water in the blow-by gas freezes increases. On the other hand, when the traveling speed V is equal to or higher than the second threshold speed V2, the amount of traveling wind received by the engine 10 increases accordingly, and the blow-by gas pipe 10 is easily deprived of heat by the traveling wind. As a result, the possibility that the water in the blow-by gas freezes increases.

As described above, the blow-by gas processing apparatus according to each embodiment of the present invention includes:
An EGR valve (63) for changing the cross-sectional area of the EGR passage (61);
A blow-by gas pipe (70) connecting between the blow-by gas discharge part of the engine 10 and the EGR passage downstream of the EGR valve in the flow of EGR gas flowing in the EGR passage;
First recirculation means (step S220) for recirculating the EGR gas through the EGR passage by opening the EGR valve when the operation state of the engine 10 is in the first operation state;
When the predetermined condition is satisfied, it is determined whether or not the predetermined condition is satisfied, in which the possibility that the water in the blow-by gas pipe is frozen is higher than when the predetermined condition is not satisfied. Determination means (step S210, step S230 and / or step S310);
By opening the EGR valve even when the engine is in a second operating state different from the first operating state when the icing occurrence condition satisfaction determining means determines that the predetermined condition is satisfied. Second reflux means (step S240) for refluxing the EGR gas through the EGR passage.

  In other words, the blow-by gas processing apparatus according to each embodiment of the present invention determines that the load (accelerator pedal operation amount Accp) and the engine rotational speed NE are determined when it is determined that the water in the blow-by gas pipe 70 may freeze. The low pressure EGR gas is recirculated through the low pressure EGR passage 61 regardless of the operation state determined by the above. As a result, the vicinity of the connecting portion between the blow-by gas pipe 70 and the low-pressure EGR passage 61 can be heated, so that the possibility that water in the blow-by gas pipe 70 is introduced into the intake passage in the ice state is reduced. Can do. As a result, since it is avoided that ice enters the compressor 35a of the supercharger 35, it is possible to avoid damage to the blades of the compressor 35a.

  The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, the blow-by gas processing apparatus according to each of the above embodiments has been applied to a four-cylinder diesel engine. However, if the engine is an internal combustion engine that includes a blow-by gas pipe and a low-pressure EGR device, ).

  Furthermore, the blow-by gas processing apparatus of the first embodiment has determined that the icing generation condition is satisfied when both of the condition 1 and the condition 2 are satisfied (see step S210 and step S220). Instead, it may be configured to determine that the icing occurrence condition is also established when only the condition 1 is satisfied or when only the condition 2 is satisfied.

  In addition, the blow-by gas processing apparatus of the second embodiment has determined that the icing generation condition is satisfied when both of the above conditions 1 to 3 are satisfied (see Step S210, Step S220, and Step 310). However, instead of this, it is determined that the icing occurrence condition is also satisfied when the two conditions of the condition 1 and the condition 3 are satisfied, or when the two conditions of the condition 2 and the condition 3 are satisfied. Can be configured to.

  Furthermore, the processing apparatus of each of the above embodiments uses “the cooling water temperature THW as a temperature representative of the engine temperature” in order to determine whether or not the icing generation condition is satisfied. However, as a temperature representative of the engine temperature, for example, an engine oil temperature acquired by an engine oil temperature sensor, an exhaust temperature acquired by an exhaust temperature sensor, or the like may be used. In addition, the engine speed NE, the accelerator pedal operation amount Accp, and the like may be used as parameters for determination in order to determine whether or not the icing occurrence condition is satisfied.

  In addition, in the embodiment, the case where water in the blow-by gas pipe freezes during operation of the engine is considered, but when the engine is stopped, for example, when the motor is running in a hybrid vehicle or when idling is stopped when the vehicle is stopped. However, if it is determined that the water in the blow-by gas pipe is likely to freeze, the above-described “blow-by gas freezing prevention control” can be executed.

  It is assumed that the hybrid vehicle that is currently traveling is switched from the engine operation to the motor operation. If traveling is continued after switching to the operation by the motor, the blow-by gas temperature in the blow-by gas pipe decreases due to the outside air temperature and the influence of traveling wind because there is no exhaust and heat supply from the engine. Although the exhaust temperature in the exhaust passage also decreases, there is an exhaust purification catalyst that can serve as a heat storage material in the exhaust passage, so that relatively high-temperature exhaust exists. Therefore, even when the engine is stopped, the possibility that the water in the blow-by gas freezes can be reduced by refluxing the gas in the exhaust passage as the low-pressure EGR gas.

  While the engine is stopped, it is difficult to recirculate the low-pressure EGR gas because there is no exhaust from the engine body. However, for example, if a low pressure EGR gas recirculation auxiliary device such as an electric pump for low pressure EGR gas recirculation is provided in the low pressure EGR passage, the low pressure EGR gas recirculation auxiliary device even when there is no exhaust from the engine body. Thus, the low pressure EGR gas can be recirculated through the low pressure EGR passage. In this case, the first throttle valve and the third throttle valve are closed by the instruction signal from the electric control device, and the second throttle valve, the high pressure EGR valve, and the low pressure EGR valve are opened. As a result, a closed circuit for circulating the low-pressure EGR gas in the engine can be created.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 20 ... Engine main-body part, 31 ... Intake passage, 34 ... 1st throttle valve (intake throttle valve), 35 ... Supercharger, 35a ... Compressor, 35b ... Turbine, 41 ... Exhaust passage, 44 ... 1st 3 throttle valve (exhaust throttle valve), 51 ... high pressure EGR passage, 53 ... high pressure EGR valve, 61 ... low pressure EGR passage, 63 ... low pressure EGR valve, 64 ... bypass passage, 65 ... bypass valve, 70 ... blow-by gas pipe.

Claims (3)

A supercharger having a compressor disposed in the intake passage of the internal combustion engine;
An EGR passage connecting the exhaust passage of the engine and the intake passage on the upstream side of the compressor;
An EGR valve that is disposed in the EGR passage and changes a cross-sectional area of the EGR passage;
A blow-by gas pipe connecting between the blow-by gas discharge part of the engine and the EGR passage downstream of the EGR valve in the flow of EGR gas flowing in the EGR passage;
A blow-by gas processing apparatus for an internal combustion engine comprising:
First recirculation means for recirculating the EGR gas through the EGR passage by opening the EGR valve when the operation state of the engine is in the first operation state;
When the predetermined condition is satisfied, it is determined whether or not the predetermined condition is satisfied, in which the possibility that the water in the blow-by gas pipe is frozen is higher than when the predetermined condition is not satisfied. A determination means;
By opening the EGR valve even when the engine is in a second operating state different from the first operating state when the icing generation condition satisfaction determining means determines that the predetermined condition is satisfied. A blow-by gas processing apparatus for an internal combustion engine, comprising: a second recirculation unit configured to recirculate the EGR gas through the EGR passage. A blow-by gas processing apparatus for an internal combustion engine according to claim 1,
The icing occurrence condition establishment determination means includes an outside air temperature acquisition means for acquiring the temperature of the outside air, and the predetermined condition is satisfied when the outside air temperature acquired by the outside air temperature acquisition means is equal to or less than a predetermined outside air temperature threshold. Then, the blow-by gas processing apparatus is configured to determine that. A blow-by gas processing apparatus for an internal combustion engine according to claim 1 or 2,
The icing occurrence condition establishment determination means includes an engine temperature acquisition means for acquiring the temperature of the engine, and the predetermined condition is satisfied when the engine temperature acquired by the engine temperature acquisition means is equal to or lower than a predetermined engine temperature threshold. A blow-by gas processing apparatus configured to determine that it is established.

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