JP6043477B2 - Blow-by gas reduction device and abnormality diagnosis method for blow-by gas reduction device - Google Patents

Description

  The present invention relates to an abnormality diagnosis technique for a blow-by gas reduction device.

  The reciprocating engine is equipped with a blow-by gas reduction device that introduces blow-by gas into the intake system and re-combusts it in order to process blow-by gas leaked from the gap between the piston and the cylinder to the crankcase. The blow-by gas reduction device includes a blow-by gas passage that introduces blow-by gas into the intake system, and a PCV (Positive Crankcase Ventilation) valve that controls the opening degree of the blow-by gas passage.

  In the blow-by gas reduction device, for example, when an abnormality such as leakage or disconnection of piping occurs in the blow-by gas passage, blow-by gas containing fuel mist is released into the atmosphere. For this reason, as described in Japanese Patent Application Laid-Open No. 2009-281225 (Patent Document 1), the intake pressure when the PCV valve opening is forcibly changed, the engine speed, the air-fuel ratio feedback correction coefficient, etc. Techniques have been proposed for diagnosing abnormalities in blow-by gas passages based on the amount of change.

JP 2009-281225 A

  However, in the blow-by gas reduction device that uses a PCV valve whose opening degree changes due to the negative pressure of the intake system, the opening degree of the PCV valve cannot be forcibly changed, and abnormality diagnosis is performed by applying the prior art. I can't.

  Therefore, an object of the present invention is to provide a blow-by gas reduction device that can perform an abnormality diagnosis of a blow-by gas passage regardless of the opening degree of a PCV valve, and an abnormality diagnosis method thereof.

The blow-by gas reduction device includes a blow-by gas passage that circulates engine blow-by gas to the intake pipe, a temperature sensor that detects the temperature of the intake air downstream of the connection of the blow-by gas passage to the intake pipe, and a control unit that includes a computer. Have. The control unit detects the temperature of the intake air with the temperature sensor in two different engine operating states, and an abnormality occurs in the blow-by gas passage when the deviation between the temperatures of the two intake air is less than a predetermined threshold value. to diagnose and there.

Regardless of the opening of the PCV valve, it is possible to diagnose whether an abnormality has occurred in the blow-by gas passage based on the temperature of the intake air flowing through the intake pipe .

Outline diagram of engine with blow-by gas reduction device Illustration of the principle of abnormality diagnosis Flow chart showing contents of control program Illustration of specific examples of abnormality diagnosis Explanatory drawing of a method to improve abnormality diagnosis accuracy

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an outline of an engine equipped with a blow-by gas reduction device.
The cylinder block 12 of the engine 10 is formed with a cylinder 12A into which the piston 14 is inserted so as to be able to reciprocate. An oil pan 16 is fastened to the lower surface of the skirt portion 12B formed below the cylinder block 12. The skirt portion 12B and the oil pan 16 form a crankcase 20 that stores the lubricating oil while rotatably accommodating the crankshaft 18.

  On the other hand, a cylinder head 26 in which an intake port 22 and an exhaust port 24 are formed is fastened to the upper surface of the cylinder block 12. The cylinder head 26 is provided with an intake valve 28 and an exhaust valve 30 slidable in the axial direction so as to open and close the openings of the intake port 22 and the exhaust port 24 facing the combustion chamber at a predetermined timing. On the upper surface of the cylinder head 26, a head cover 34 in which a valve operating mechanism 32 for opening and closing the intake valve 28 and the exhaust valve 30 is housed is fastened.

  An intake pipe 36 (intake system) that communicates with the intake port 22 cools the intake air that has passed through the air cleaner 38 that filters the dust in the intake air, the compressor 40A of the turbocharger 40, and the turbocharger 40 along the intake air circulation direction. Intercoolers 42 are arranged in this order. On the other hand, a turbine 40 </ b> B of the turbocharger 40 is disposed in the exhaust pipe 44 that communicates with the exhaust port 24. A known exhaust purification device (not shown) is disposed in the exhaust pipe 44 located downstream of the turbine 40B.

  The intake pipe 36 positioned downstream of the intercooler 42 and the exhaust pipe 44 positioned upstream of the turbine 40B are communicated via an EGR (Exhaust Gas Recirculation) passage 46, and the opening degree is continuously or in multiple stages. A remotely controllable EGR valve 48 is provided. Then, by increasing or decreasing the opening degree of the EGR valve 48 according to the engine operating state, a part of the exhaust gas is circulated to the intake system, and the emission amount of nitrogen oxides (NOx) is reduced through a decrease in the combustion temperature.

  The cylinder block 12 and the cylinder head 26 are formed with a communication passage 50 that guides the blow-by gas leaked to the crankcase 20 through the gap between the piston 14 and the cylinder 12 </ b> A to the internal space of the head cover 34. The internal space of the head cover 34 is connected in communication with an intake pipe 36 located between the air cleaner 38 and the compressor 40A of the turbocharger 40 via a blow-by gas passage 52 made of piping or tubes. The blow-by gas passage 52 is provided with an oil mist separator 54 that separates oil mist contained in the blow-by gas.

  The oil mist separator 54 incorporates a PCV valve mechanism that increases or decreases the opening degree of the blow-by gas passage 52 by the intake negative pressure in the intake pipe 36. The opening degree of the PCV valve mechanism is small when the intake negative pressure is small as in idling, while the opening degree is large when the intake negative pressure is large as in acceleration.

  The oil mist separated by the oil mist separator 54 is returned from the skirt portion 12B of the cylinder block 12 to the oil pan 16 via an oil return passage 56 made of piping, tubes, or the like.

  An intake pipe 36 located between the air cleaner 38 and the compressor 40 </ b> A of the turbocharger 40, and a connection part of the blow-by gas passage 52 with respect to the intake pipe 36 is used for grasping the circulation state of the blow-by gas. A temperature sensor 58 for detecting the temperature of the intake air (intake air temperature) T flowing through is attached. The output signal of the temperature sensor 58 is input to a control unit 60 incorporating a computer. The control unit 60 also receives output signals from a rotation speed sensor 62 that detects the rotation speed Ne of the engine 10 and a load sensor 64 that detects the load Q of the engine 10. Here, as the load Q of the engine 10, for example, a state quantity closely related to the engine torque such as an intake flow rate, an intake negative pressure, a boost pressure, a fuel injection amount, an accelerator opening degree, a throttle opening degree, and the like is applied. Can do. The rotational speed Ne and the load Q of the engine 10 may be read from another control unit connected by a CAN (Controller Area Network) or the like.

  The control unit 60 electronically controls the EGR valve 48 based on the rotational speed Ne and the load Q in accordance with a control program stored in a non-volatile memory such as a flash ROM (Read Only Memory). An abnormality diagnosis of the blow-by gas passage 52 is performed based on the Q and the intake air temperature T.

Here, the abnormality diagnosis principle of the blow-by gas passage 52 will be described.
When there is no abnormality such as leakage or disconnection in the blow-by gas passage 52 that connects the head cover 34 and the intake pipe 36, the blow-by gas in the crankcase 20 uses the negative pressure in the intake pipe 36. Thus, the air is circulated to the intake pipe 36 through the communication passage 50 and the internal space of the head cover 34. In this case, as shown in FIG. 2, since the blow-by gas is mixed with the intake air (fresh air) flowing through the intake pipe 36, the temperature sensor 58 disposed at the connection portion of the blow-by gas passage 52 with respect to the intake pipe 36 is connected to the blow-by gas. The intake air temperature mixed with is detected. Since the flow rate of blow-by gas increases as the engine speed and load increase, the mixing ratio of intake air (fresh air) and blow-by gas changes according to the engine speed and load. Since the temperature TA of the intake air (fresh air) is substantially constant and the temperature TB of the blow-by gas is higher than the temperature TA of the intake air, the intake temperature detected by the temperature sensor 58 is increased by changing the mixing ratio of both. Change.

  On the other hand, when an abnormality such as leakage or pipe disconnection occurs in the blow-by gas passage 52, the blow-by gas in the crankcase 20 is not circulated to the intake pipe 36. In this case, the blow-by gas is not mixed with the intake air (fresh air) flowing through the intake pipe 36, and the ambient air around the engine introduced from the location where the blow-by gas passage 52 is abnormal is mixed with the intake air (fresh air). 58 detects the intake air temperature at which the ambient air around the engine is mixed. Since the mixing ratio between the intake air (fresh air) and the ambient air around the engine is substantially constant regardless of the engine speed and load, the intake air temperature detected by the temperature sensor 58 changes significantly even if the engine operating state changes. do not do.

  Therefore, based on the intake air temperature T at the connection portion of the blow-by gas passage 52 with respect to the intake pipe 36, it is possible to diagnose whether or not an abnormality such as leakage or pipe disconnection has occurred in the blow-by gas passage 52.

FIG. 3 shows the contents of a control program that the control unit 60 repeatedly executes at predetermined time intervals when the engine 10 is started.
In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), whether or not the control unit 60 has detected the intake air temperature T in the first engine operating state (for example, idling state) as an initialization process. And Flag2 for determining whether or not the intake air temperature T in the second engine operation state (for example, high load / high rotation state) has been detected are set to 0 (undetected), respectively. Set.

  In step 2, the control unit 60 determines whether or not the engine 10 is in the first engine operating state and Flag1 is 0 (not detected). That is, the control unit 60 reads the rotational speed Ne from the rotational speed sensor 62, reads the load Q from the load sensor 64, the rotational speed Ne is the first predetermined rotational speed A1, and the load Q is the first predetermined load. It is determined whether or not the engine 10 is in the first engine operating state through whether or not it is B1. Here, the first predetermined rotation speed A1 and the first predetermined load B1 are threshold values that specify the first engine operating state, and may have a width defined by an upper limit value and a lower limit value. . Then, if the control unit 60 determines that the engine 10 is in the first engine operating state and Flag1 is 0, the process proceeds to step 3 (Yes), but if it is determined that it is other than that. The process proceeds to step 5 (No).

  In step 3, the control unit 60 reads the intake air temperature T from the temperature sensor 58, and substitutes the intake air temperature T into a variable C1 that temporarily stores the intake air temperature in the first engine operating state.

In Step 4, since the control unit 60 detects the intake air temperature in the first engine operating state, Flag1 is set to 1 (detected).
In step 5, the control unit 60 determines whether or not the engine 10 is in the second engine operating state and Flag2 is 0 (not detected). That is, the control unit 60 reads the rotational speed Ne from the rotational speed sensor 62, reads the load Q from the load sensor 64, the rotational speed Ne is the second predetermined rotational speed A2, and the load Q is the second predetermined load. It is determined whether or not the engine 10 is in the second engine operating state through whether or not it is B2. Here, the second predetermined rotational speed A2 and the second predetermined load B2 are threshold values for specifying the second engine operating state, and may have a width defined by an upper limit value and a lower limit value. . Then, if the control unit 60 determines that the engine 10 is in the second engine operating state and Flag2 is 0, the process proceeds to step 6 (Yes), but if it is determined that it is other than that. The process proceeds to step 8 (No).

  In step 6, the control unit 60 reads the intake air temperature T from the temperature sensor 58, and substitutes the intake air temperature T into a variable C2 that temporarily stores the intake air temperature in the second engine operating state.

In step 7, since the control unit 60 detects the intake air temperature in the second engine operating state, Flag2 is set to 1 (detected).
In step 8, the control unit 60 determines whether or not Flag1 and Flag2 are both 1, that is, whether or not the intake air temperature in the first engine operating state and the second engine operating state has been detected. The control unit 60 advances the process to step 9 if it is determined that both Flag1 and Flag2 are 1 (Yes), and returns the process to step 2 if it is determined otherwise (No).

  In step 9, the control unit 60 determines the absolute value of the difference between the variable C1 and the variable C2, that is, the absolute value of the difference between the intake air temperature in the first engine operating state and the intake air temperature in the second engine operating state. It is determined whether or not it is larger than the threshold value. Here, as the predetermined threshold value, a value that can determine whether or not there is an abnormality such as leakage in the blow-by gas passage 52 or disconnection of the pipe as in the above-described abnormality diagnosis principle can be appropriately adopted. Then, if the control unit 60 determines that the absolute value of the difference between the variable C1 and the variable C2 is larger than the predetermined threshold, the process proceeds to step 10 (Yes), while the absolute value of the difference between the variable C1 and the variable C2 If it is determined that is less than or equal to the predetermined threshold, the process proceeds to step 11 (No).

  In step 10, when the operating state of the engine 10 changes, the intake air temperature at the connection portion of the blow-by gas passage 52 with respect to the intake pipe 36 greatly increases and decreases, so that the control unit 60 determines that the blow-by gas passage 52 is normal (no abnormality). Diagnose.

  In step 11, even if the operating state of the engine 10 changes, the intake air temperature at the connection portion of the blow-by gas passage 52 with respect to the intake pipe 36 does not increase or decrease so much, so the control unit 60 diagnoses that the blow-by gas passage 52 is abnormal. . When it is diagnosed that the blow-by gas passage 52 is abnormal, for example, a warning lamp may be turned on to notify the driver of the occurrence of abnormality.

  According to this blow-by gas reduction device, as shown in FIG. 4, the engine 10 is in the first engine operating state in which the rotational speed Ne is the first predetermined rotational speed A1 and the load Q is the first predetermined load B1. Sometimes, the intake air temperature T at the connection of the blow-by gas passage 52 to the intake pipe 36 is stored in the variable C1. Further, when the engine 10 is in the second engine operating state in which the rotation speed Ne of the engine 10 is the second predetermined rotation speed A2 and the load Q is the second predetermined load B2, the connection portion of the blow-by gas passage 52 to the intake pipe 36. Is stored in the variable C2. If the absolute value (deviation) of the difference between the variable C1 indicating the intake air temperature in the first engine operating state and the variable C2 indicating the intake air temperature in the second engine operating state is greater than a predetermined threshold, the blow-by gas passage 52 is Diagnosed as normal. On the other hand, if the absolute value of the difference between the variable C1 indicating the intake air temperature in the first engine operating state and the variable C2 indicating the intake air temperature in the second engine operating state is equal to or less than a predetermined threshold, the blow-by gas passage 52 is abnormal. Diagnosed to be.

  At this time, if the idling state is adopted as the first engine operating state and the high load / high rotation state is adopted as the second engine operating state, through comparison of intake air temperatures in two greatly different engine operating states, It is possible to diagnose whether or not an abnormality has occurred in the blow-by gas passage 52. For this reason, abnormality diagnosis accuracy can be improved.

  Further, the intake air temperature at the connection portion of the blow-by gas passage 52 with respect to the intake pipe 36 depends on whether or not an abnormality has occurred in the blow-by gas passage 52, as shown in FIG. The fluctuation range varies greatly with the change of Q. For this reason, in order to further improve the abnormality diagnosis accuracy, in addition to the absolute value of the difference between the variable C1 and the variable C2 being equal to or less than a predetermined threshold, the intake air temperature fluctuates beyond a predetermined range as the engine operating state changes. In such a case, it may be diagnosed that an abnormality has occurred in the blow-by gas passage 52.

  Furthermore, the abnormality diagnosis of the blow-by gas passage 52 is not limited to the control unit 60, and may be performed in another control unit such as an engine control unit that electronically controls the engine 10, for example.

10 Engine 36 Intake pipe (intake system)
52 Blow-by gas passage 58 Temperature sensor 60 Control unit 62 Rotational speed sensor 64 Load sensor

Claims (5)

A blow-by gas passage for circulating the engine blow-by gas to the intake pipe;
A temperature sensor that detects the temperature of the intake air downstream of the connection of the blow-by gas passage to the intake pipe;
A control unit with a built-in computer,
Have
When the control unit detects the temperature of intake air by the temperature sensor in two different engine operating states, and the deviation between the temperatures of the two intake air is less than or equal to a predetermined threshold, an abnormality occurs in the blow-by gas passage. A blow-by gas reduction device, characterized in that it is diagnosed. One of the two engine operating states is a first engine operating state in which the engine rotational speed is a first predetermined rotational speed and the engine load is a first predetermined load.
The other of the two engine operating states is a second predetermined rotation speed in which the engine rotation speed is higher than the first predetermined rotation speed and the engine load is larger than the first predetermined load. Is the second engine operating state,
The blow-by gas reduction apparatus according to claim 1. The first engine operating state is an idling state,
The second engine operation state is a high load / high rotation state,
The blowby gas reduction apparatus according to claim 2, wherein When the control unit detects that the temperature difference between the two intake air is less than or equal to a predetermined threshold, and the temperature of the intake air detected by the temperature sensor fluctuates beyond a predetermined width due to a change in the engine operating state. The blow-by gas reduction device according to any one of claims 1 to 3 , wherein a diagnosis is made that an abnormality has occurred in the blow-by gas passage . A blow-by gas passage for circulating the engine blow-by gas to the intake pipe;
A temperature sensor that detects the temperature of the intake air downstream of the connection of the blow-by gas passage to the intake pipe;
A control unit with a built-in computer,
An abnormality diagnosis method for a blow-by gas reduction device having
When the control unit detects the temperature of intake air by the temperature sensor in two different engine operating states, and the deviation between the temperatures of the two intake air is less than or equal to a predetermined threshold, an abnormality occurs in the blow-by gas passage. An abnormality diagnosis method for a blow-by gas reduction device, characterized by: