JP2021120565A - Device for detecting adhesion of deposit - Google Patents

Abstract

To provide a device for detecting adhesion of deposits, which can accurately detect adhesion of deposits onto an intake port.SOLUTION: An engine 1 has an intake port 32 that introduces fresh air into a combustion chamber 31 and is opened and closed at predetermined valve timing by an intake valve 34, an intake flow passage 41 that introduces the fresh air into the intake port, and a throttle valve 43 that is provided in the middle of the intake air passage. A device for detecting adhesion of deposits, which is provided on the engine includes a communication flow passage 80 that puts a part of an inner surface of the intake port into communication with a region on the upstream side of the throttle valve in the intake air passage, a pressure sensor 82 that detects pressure inside of the communication flow passage, a valve 81 that is provided in the communication flow passage and can be transited between an open state and a close state, and an adhesion amount detection part 100 that detects a deposit adhesion amount on the intake port on the basis of a change in a detection value of the pressure sensor after the state of the valve is transited.SELECTED DRAWING: Figure 1

Description

The present invention relates to a device for detecting deposit deposits on an engine intake port.

For example, in an automobile engine, the gas (blow-by gas) that blows through the crankcase from the combustion chamber via the gap of the piston ring is reintroduced into the combustion chamber and burned, so a dedicated pipe is used. Introduced in the intake pipeline.
The blow-by gas introduced into the intake line contains a mist of lubricating oil in the crankcase and other incomplete combustion products.
Such oil mists and incomplete combustion products may form deposits in the intake port, which is the flow path for introducing fresh air into the combustion chamber.
If the deposit amount is excessively large, there are concerns about problems such as deterioration of engine startability.
In the past, deposits in the intake port were generally checked by disassembling the engine and visually inspecting it, but in this case, it is necessary to take a subsequent measure after some performance deterioration occurs. Therefore, there is a demand for a technique for detecting deposit adhesion without disassembling the engine.

As a conventional technique for detecting deposit adhesion to an engine intake device, for example, Patent Document 1 states that the intake pressure is increased even though the intake air amount of the engine detected by the air flow meter does not change with time. In some cases, it is stated that it is determined that the amount of valve deposit deposited on the intake valve is increasing.

Japanese Unexamined Patent Publication No. 2006-31280

According to the technique described in Patent Document 1, it is possible to detect deposit adhesion to the intake valve and the intake port during operation of the engine, but a considerably large amount of deposit is generated to the extent that the intake pressure of the engine changes. If it does not adhere, it is considered difficult to detect.
If deposits adhere to such a degree, it is inevitable that significant performance deterioration will occur in the engine, and there is a demand for a technology that can detect deposit deposits at an earlier stage.
In view of the above-mentioned problems, an object of the present invention is to provide a deposit adhesion detecting device capable of accurately detecting deposit adhesion of an intake port.

The present invention solves the above-mentioned problems by the following solutions.
The invention according to claim 1 has an intake port that introduces fresh air into a combustion chamber and is opened and closed at a predetermined valve timing by an intake valve, an intake flow path that introduces fresh air into the intake port, and the intake flow path. A deposit adhesion detection device provided in an engine having a throttle valve provided in the middle of the above, which communicates a part of the inner surface of the intake port with a region of the intake flow path on the upstream side of the throttle valve. After changing the state of the communication flow path, the pressure sensor that detects the pressure inside the communication flow path, the valve provided in the communication flow path that can change between the open state and the closed state, and the state of the valve. It is a deposit adhesion detection device including a deposit amount detection unit that detects a deposit adhesion amount of the intake port based on a change in a detection value of the pressure sensor.
If a deposit is attached to the inner surface of the intake port, the deposit is also attached to the opening end of the communication flow path on the intake port side. When this end is partially closed, the flow path resistance and pressure loss increase, and the flow velocity when the air flow passes through the inside decreases.
When the state of the valve is changed in such a state and the pressure in the communication flow path is changed, if the amount of deposit is large, the time required for the pressure change becomes long.
According to the present invention, the deposit is detected based on the change in the detected value of the pressure sensor after the state of the valve is changed, so that the deposit is not significantly different in the intake pipe pressure of the engine. Even if it is, it can be detected with high accuracy.

The invention according to claim 2 is characterized in that the adhesion amount detecting unit detects the deposit adhesion amount based on the rate of change of the detection value of the pressure sensor after the state of the valve is changed. Item 2. The deposit adhesion detection device according to item 1.
According to this, the above-mentioned effect can be surely obtained by a simple configuration.
The predetermined value can be set based on, for example, the rate of change of the detected value of the pressure sensor after the state of the valve is changed in the normal state of the engine (the state where the deposit is not attached to the intake port).

The invention according to claim 3 is characterized in that the end portion of the communication flow path on the intake port side is arranged at a position adjacent to a valve seat in contact with the peripheral edge of the valve body portion of the intake valve. Alternatively, the deposit adhesion detection device according to claim 2.
According to this, it is possible to appropriately detect the state of local deposit adhesion at a location close to the valve seat where deposit accumulation is likely to be a problem.

As described above, according to the present invention, it is possible to provide a deposit adhesion detecting device capable of accurately detecting the deposit adhesion of the intake port.

It is a figure which shows typically the structure of the engine which has the embodiment of the deposit adhesion detection apparatus to which this invention is applied. It is a flowchart which shows the operation of the deposit adhesion detection apparatus of embodiment. It is a figure which shows an example of the transition of the pressure sensor detection value in the deposit adhesion detection apparatus of embodiment.

Hereinafter, embodiments of a deposit adhesion detection device to which the present invention is applied will be described.
FIG. 1 is a diagram schematically showing a configuration of an engine having a deposit adhesion detecting device of the embodiment.
The engine 1 includes a cylinder block 10, a piston 20, a cylinder head 30, an intake device 40, an exhaust device 50, an injector 60, a blow-by gas flow path 70, a deposit detection flow path 80, an engine control unit 100, and the like. There is.

The cylinder block 10 is formed by integrally forming a sleeve into which the piston 20 is inserted and a crankcase.
The crankcase rotatably supports and accommodates a crankshaft (not shown), which is an output shaft of the engine 1.
The cylinder block 10 is provided with a water temperature sensor 11 that detects the temperature of the cooling water flowing through the water jacket formed around the cylinder head 30 and the sleeve.
The output of the water temperature sensor 11 is transmitted to the engine control unit 100.
The end portion of the blow-by gas flow path 70 is connected to the crankcase portion of the cylinder block 10 in a state of communicating with the inside.

The piston 20 is a member that is inserted into the sleeve of the cylinder block 10 and reciprocates.
The piston 20 is connected to a crankshaft (not shown) via a connecting rod 21.
The crown surface 22 of the piston 20 cooperates with the cylinder head 30 to form the combustion chamber of the engine 1.

The cylinder head 30 is provided at an end of the cylinder block 10 opposite to the crankshaft side.
The cylinder head 30 includes a combustion chamber 31, an intake port 32, an exhaust port 33, an intake valve 34, an exhaust valve 35, a spark plug 36, and the like.

The combustion chamber 31 is a recess formed so as to face the crown surface 22 of the piston 20, and is formed in, for example, a pent roof type.
The intake port 32 is a flow path for introducing combustion air (fresh air) into the combustion chamber 31.
The exhaust port 33 is a flow path for discharging burned gas (exhaust gas) from the combustion chamber 31.
The intake valve 34 and the exhaust valve 35 open and close the intake port 32 and the exhaust port 33 at predetermined valve timings, respectively.
The intake valve 34 and the exhaust valve 35 are driven by a valve drive system such as a camshaft and a rocker arm.
The spark plug 36 generates sparks at a predetermined ignition timing in response to an ignition signal generated by the engine control unit 100, and ignites the air-fuel mixture.
The spark plug 36 is arranged substantially at the center of the combustion chamber 31 (near the central axis of the sleeve of the cylinder block 10).

The intake device 40 introduces combustion air into the engine 1.
The intake device 40 includes an intake duct 41, an air cleaner 42, a throttle valve 43, an intake manifold 44, an air flow meter 45, and the like.
The intake duct 41 is a pipeline (intake flow path) that introduces air from the atmosphere and supplies it to the engine 1.
The air cleaner 42 is provided near the inlet of the intake duct 41 and filters and purifies dust and the like in the air.
The throttle valve 43 is provided on the downstream side of the air cleaner 42 in the intake duct 41, and adjusts the output of the engine 1 by reducing the amount of intake air.
The throttle valve 43 includes a valve body such as a butterfly valve, an electric actuator (throttle actuator) for driving the valve body, a throttle sensor for detecting a throttle opening degree, and the like.
The throttle actuator is driven in response to a control signal from the engine control unit 100.
The intake manifold 44 is provided on the downstream side of the throttle valve 43, and includes a surge tank formed in a container shape and a branch pipe connected to the intake port 32 of each cylinder to introduce fresh air. ..
The air flow meter 45 is an intake air amount sensor provided on the downstream side of the air cleaner 42 and measuring the flow rate of air passing through the intake duct 41 (intake flow rate of the engine 1).
The output of the air flow meter 45 is sequentially transmitted to the engine control unit 100.

The exhaust device 50 discharges exhaust gas from the engine 1.
The exhaust device 50 includes an exhaust pipe 51, a catalytic converter 52, an air-fuel ratio sensor 53, a rear O ₂ sensor 54, and the like.
The exhaust pipe 51 is a pipeline for discharging the exhaust gas emitted from the exhaust port 33.
The catalytic converter 52 is provided in the middle portion of the exhaust pipe 51.
The catalyst converter 52 is configured by supporting a precious metal such as platinum or rhodium on a honeycomb-shaped alumina carrier, and includes a three-way catalyst for purifying HC, NOx, CO and the like.

The air-fuel ratio (A / F) sensor 53 is a linear output lambda sensor that detects the current excess air ratio λ of the engine 1 based on the properties of the exhaust gas.
The air-fuel ratio sensor 53 is provided in a region upstream of the catalytic converter 52 of the exhaust pipe 51.

The rear O ₂ sensor 54 detects the oxygen content in the exhaust gas after passing through the catalytic converter 52.
The rear O ₂ sensor 54 is configured by coating the inner surface (atmosphere side) and the outer surface (exhaust gas side) of a cylinder made of zirconia with platinum, respectively, and generates an electromotive force due to an oxygen concentration difference. ..
The rear O ₂ sensor 54 generates a voltage when the air-fuel ratio is higher than the theoretical air-fuel ratio (fuel rich state / oxygen deficient state), and substantially a voltage when the air fuel ratio is low (fuel lean state / oxygen surplus state). Has the property of not occurring.
The rear O ₂ sensor 54 is provided in a region downstream of the catalytic converter 52 of the exhaust pipe 51.

The injector 60 includes, for example, a needle valve driven by an actuator having a solenoid or a piezo element, and an injection signal generated by the engine control unit 100 for high-pressure fuel pumped from a high-pressure fuel pump (not shown) and accumulated in a delivery pipe. In response to the (valve opening signal), a predetermined injection amount is injected into the combustion chamber 31 at a predetermined time.

The blow-by gas flow path 70 recirculates the gas (blow-by gas) that has blown from the combustion chamber 31 to the crankcase side of the cylinder block 10 to the intake device 40 for combustion processing in the combustion chamber 31.
Blow-by gas contains oil mist and other incomplete combustion products that are mixed in the crankcase.
The blow-by gas flow path 70 is connected to the crankcase portion of the cylinder block 10 and the region of the intake duct 41 downstream of the throttle valve 43 (cylinder head 30 side) in a state of communication with each other.
A valve 71 is provided in the middle of the blow-by gas flow path 70.
The valve 71 is a solenoid valve that opens and closes in response to a command from the engine control unit 100.
The valve 71 is opened, for example, when the intake pipe pressure on the downstream side of the throttle valve 43 is in a range suitable for processing blow-by gas.

The deposit detection flow path 80 is a pipe (communication flow path) that communicates the intake port 32 with the region of the intake duct 41 on the upstream side (air cleaner 42 side) of the throttle valve 43.
The end of the deposit detection flow path 80 on the intake port 32 side is open in the intake port 32 at a location where deposit accumulation is likely to occur.
For example, the end portion of the deposit detection flow path 80 on the intake port 32 side can be arranged at a position adjacent to the valve seat with which the peripheral edge portion of the valve body of the intake valve 34 abuts.

A valve 81 and a pressure sensor 82 are provided in the middle portion of the deposit detection flow path 80 in this order from the intake duct 41 side.
The valve 81 is a solenoid valve that opens and closes in response to a command from the engine control unit 100.
The valve 81 is maintained in the closed state during the normal operation of the engine 1, and is temporarily opened when the deposit adhesion detection of the intake port 32 is performed.
The pressure sensor 82 detects the pressure inside the deposit detection flow path 80 on the intake port 32 side of the valve 81.

The engine control unit 100 comprehensively controls the engine 1 and its accessories.
The engine control unit 100 includes, for example, an information processing unit such as a CPU, a storage unit such as a RAM or ROM, an input / output interface, and a bus connecting these.
The engine control unit 100 sets the required torque based on, for example, the amount of operation of the accelerator pedal by the driver, and performs output control so that the actual output torque of the engine 1 matches the required torque.

Further, in the embodiment, the engine control unit 100 cooperates with the deposit detection flow path 80 to function as a deposit adhesion detecting device for detecting the deposit deposit amount of the intake port 32 (function as a deposit amount detecting unit). Has.
This point will be described in detail below.
FIG. 2 is a flowchart showing the operation of the deposit adhesion detection device of the embodiment.

<Step S01: Judgment of deposit detectable condition>
The engine control unit 100 determines whether or not the current operating state of the engine 1 satisfies a predetermined condition suitable for deposit adhesion detection.
For example, if the engine speed (crankshaft speed) and output torque are within preset predetermined ranges and there is no significant fluctuation in these, deposit adhesion detection is possible. judge.
For example, it can be determined that the deposit adhesion detection is possible when the engine 1 is in the idling state.
If it is determined that the deposit adhesion detection is possible, the process proceeds to step S02, and in other cases, a series of processes is completed (returned).

<Step S02: Transition to valve open state>
The engine control unit 100 changes the valve 81 of the deposit detection flow path 80 from the closed state to the open state.
When the engine 1 is operated with a relatively low load, the throttle valve 43 is in a throttled state, and the pressure in the intake pipe is lower on the downstream side of the throttle valve 43 than on the upstream side.
Therefore, when the valve 81 is opened, the air in the deposit detection flow path 80 flows from the intake duct 41 side to the intake port 32 side due to the pressure difference, and flows into the intake port from the end portion on the intake port 32 side.
Then, the process proceeds to step S03.

<Step S03: Acquisition of pressure sensor output>
The engine control unit 100 acquires the output (pressure detection value) of the pressure sensor 82 and holds it in the storage unit.
Then, the process proceeds to step S04.

<Step S04: Open state timer value count up>
The engine control unit 100 counts up the timer value of the timer means (open state timer) that measures the elapsed time after the valve 81 is changed to the open state in step S02.
The timer value is reset at the start of deposit adhesion detection.
Then, the process proceeds to step S05.

<Step S05: Judgment of pressure increase amount>
The engine control unit 100 compares the amount of increase in pressure in the deposit detection flow path 80 after the valve 81 is changed to the open state in step S02 with a preset threshold value ThP (see FIG. 3).
The threshold value ThP can be set based on, for example, the pressure in the intake duct 41 on the upstream side of the throttle valve 43 (in the case of a naturally aspirated engine, it is equivalent to the atmospheric pressure).
If the amount of pressure increase is equal to or greater than the threshold value ThP, the process proceeds to step S06, and if not, the process returns to step S03, and the subsequent processing is repeated.

<Step S06: Transition to valve closed state>
The engine control unit 100 changes the valve 81 from the open state to the closed state.
Then, the process proceeds to step S07.

<Step S07: Judgment of open timer value>
The engine control unit 100 compares the timer value T of the current open state timer (the time from when the valve 81 is opened until the pressure increase amount reaches the threshold value ThP) with the preset threshold value ThT (see FIG. 3). ..
The timer value T at this time indicates the pressure increase rate in the deposit detection flow path 80 after the valve 81 is opened.
This threshold ThT is such that when no deposit is attached to the intake port 32, the time from when the valve 81 is opened until the pressure reaches the threshold ThP is a predetermined allowable time (which does not affect the operation of the engine 1). The delay time when a deposit is attached) can be added and set.
If the open state timer value is equal to or higher than the threshold value ThT, the process proceeds to step S08, and in other cases, the process proceeds to step S09.

<Step S08: Deposit accumulation judgment established>
The engine control unit 100 determines that the deposit detection flow path 80 is in a deposit accumulation state in which a predetermined amount or more of the deposit is attached to the open end on the intake port 32 side.
The engine control unit 100 switches the operation control of the engine 1 to a predetermined safe mode control, and notifies the user that a deposit accumulation state has occurred by lighting a warning light (MIL) or the like.
The engine control unit 100 can also estimate the deposit amount according to the deviation of the open state timer value from the threshold value.
After that, a series of processes is completed.

<Step S09: Deposit accumulation judgment unsuccessful>
The engine control unit 100 determines that no deposit accumulation state has occurred.
After that, a series of processes is completed.

FIG. 3 is a diagram showing an example of a transition of the pressure sensor detection value in the deposit adhesion detection device of the embodiment.
In FIG. 3, the horizontal axis represents time and the vertical axis represents pressure in the deposit detection flow path 80.
When the valve 81 is closed and the engine 1 is in steady operation (for example, in an idling state) with the throttle valve 43 throttled, the pressure in the deposit detection flow path 80 at the location where the pressure sensor 82 is provided is , The pressure is equal to the pressure in the intake port 32 (so-called negative pressure in the intake pipe), and is lower than the pressure in the intake duct 41 on the upstream side of the throttle valve 43 (almost equivalent to the atmospheric pressure).

After that, when the valve 81 is opened to detect the deposit adhesion, air flows from the intake duct 41 side to the intake port 32 side due to the pressure difference described above, and the pressure detected by the pressure sensor 82 starts to increase, and then reaches the threshold value ThP. Reach.
When the pressure reaches the threshold ThP, the valve 81 is closed and the pressure begins to drop.
Here, when a deposit is accumulated, the flow path resistance (pressure loss) at the open end of the deposit detection flow path 80 increases, so that the time from when the valve 81 is opened until the pressure reaches the threshold value ThP. (Timer value T) becomes large. (The rate of increase in pressure slows down.)
When the timer value T is equal to or higher than the threshold value ThT, it can be determined that the deposit is in a deposit accumulation state in which a predetermined or higher deposit is attached.

As described above, according to the present embodiment, the following effects can be obtained.
(1) By detecting the adhesion of the deposit based on the increase in the pressure detected by the pressure sensor 82 after the valve 81 is changed from the closed state to the open state, there is no significant difference in the intake pipe pressure of the engine 1. Even a small amount of deposit can be detected with high accuracy.
For example, the deposit-attached state can be detected from the state in which the deposit is not attached to the state in which the deposit detection flow path 80 is completely blocked.
(2) The time until the pressure detected by the pressure sensor 82 increases to the threshold value ThP after opening the valve 81 (meaning the rate of increase in pressure) is compared with the threshold value ThT set based on the normal data. By making the determination, the above-mentioned effect can be surely obtained with a simple configuration.
(3) By arranging the end of the deposit detection flow path 80 on the intake port 32 side in the vicinity of the valve seat, the state of local deposit adhesion in the vicinity of the valve seat where deposit accumulation is likely to be a problem is appropriately maintained. Can be detected.

(Modification example)
The present invention is not limited to the embodiments described above, and various modifications and modifications can be made, and these are also within the technical scope of the present invention.
(1) The configuration of the deposit adhesion detection device and the engine is not limited to the above-described embodiment, and can be appropriately changed.
For example, the number of cylinders of the engine, the cylinder layout, the fuel injection method, and the like can be changed as appropriate.
Further, although the engine is a gasoline engine as an example in the embodiment, the present invention can be applied to other types of engines having a throttle valve.
(2) The engine of the embodiment is a naturally aspirated engine as an example, but the present invention can also be applied to a supercharged engine.
For example, when the engine is equipped with a turbocharger, the end of the deposit detection flow path opposite to the intake port side can be connected to the inlet side of the compressor of the turbocharger.
(3) In the embodiment, the deposit adhesion is detected based on the pressure increase time after the valve is opened in the steady state, but the pressure decrease time when the valve is closed after the valve is opened and the pressure rises. Deposit adhesion may be detected based on.
In addition, deposit adhesion may be detected based on both the increase time and the decrease time of such pressure.

1 Engine 10 Cylinder block 11 Water temperature sensor 20 Piston 21 Conrod 22 Crown surface 30 Cylinder head 31 Combustion chamber 32 Intake port 33 Exhaust port 34 Intake valve 35 Exhaust valve 36 Ignition plug 40 Intake device 41 Intake duct 42 Air cleaner 43 Throttle valve 44 Intake manifold 45 Airflow meter 50 Exhaust device 51 Exhaust pipe 52 Catalytic converter 53 Air fuel ratio sensor 54 Rear O ₂ sensor 60 Injector 70 Blow-by gas flow path 71 Valve 80 Deposit detection flow path 81 Valve 82 Pressure sensor

Claims (3)

An intake port that introduces fresh air into the combustion chamber and is opened and closed at a predetermined valve timing by the intake valve,
An intake flow path that introduces fresh air into the intake port,
A deposit adhesion detection device provided in an engine having a throttle valve provided in the middle of the intake flow path.
A communication flow path that communicates a part of the inner surface of the intake port with a region of the intake flow path on the upstream side of the throttle valve.
A pressure sensor that detects the pressure inside the communication flow path and
A valve provided in the communication flow path that can change between an open state and a closed state,
A deposit adhesion detecting device including a deposit amount detecting unit that detects a deposit adhesion amount of the intake port based on a change in a detected value of the pressure sensor after the state of the valve is changed. The deposit adhesion detection according to claim 1, wherein the adhesion amount detecting unit detects the deposit adhesion amount based on the rate of change of the detection value of the pressure sensor after the state of the valve is changed. Device. The deposit according to claim 1 or 2, wherein the end portion of the communication flow path on the intake port side is arranged at a position adjacent to the valve seat in contact with the peripheral edge of the valve body portion of the intake valve. Adhesion detection device.

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