WO2015141544A1 - Control device for internal combustion engine - Google Patents

Control device for internal combustion engine Download PDF

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Publication number
WO2015141544A1
WO2015141544A1 PCT/JP2015/057222 JP2015057222W WO2015141544A1 WO 2015141544 A1 WO2015141544 A1 WO 2015141544A1 JP 2015057222 W JP2015057222 W JP 2015057222W WO 2015141544 A1 WO2015141544 A1 WO 2015141544A1
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WO
WIPO (PCT)
Prior art keywords
control
temperature range
heater
temperature
deposit
Prior art date
Application number
PCT/JP2015/057222
Other languages
French (fr)
Inventor
Junichi MURASE
Koseki SUGIYAMA
Original Assignee
Toyota Jidosha Kabushiki Kaisha
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Jidosha Kabushiki Kaisha filed Critical Toyota Jidosha Kabushiki Kaisha
Priority to CN201580013898.9A priority Critical patent/CN106103974B/en
Priority to EP15713245.7A priority patent/EP3120013B1/en
Publication of WO2015141544A1 publication Critical patent/WO2015141544A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
    • F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
    • F02P19/028—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs the glow plug being combined with or used as a sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D41/222—Safety or indicating devices for abnormal conditions relating to the failure of sensors or parameter detection devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
    • F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
    • F02P19/026—Glow plug actuation during engine operation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
    • F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
    • F02P19/027—Safety devices, e.g. for diagnosing the glow plugs or the related circuits

Definitions

  • the present invention relates to a control device for an internal combustion engine.
  • the invention relates to a control device for an internal combustion engine using a glow plug-integrated type cylinder pressure sensor.
  • Literature 1 discloses the device which estimates the amount of deposit that accumulates between the cylinder head of the internal combustion engine and the pressure receiving section when the internal combustion engine is in a predetermined operation state, and controls energization to the heating element based on the estimated amount.
  • energization to the heating element can be controlled based on the estimated amount. Accordingly, even if deposit accumulates between the cylinder head and the pressure receiving section, the temperature of the heater is increased, and thereby the deposit can be decomposed and removed.
  • Patent Literature 2 discloses the device which performs energization control to a heating element with two different objectives. More specifically, in this device, start time control with the objective of improving start stability of an internal combustion engine is executed, and thereafter, deposit restraint control with the objective of restraining adhesion of deposit to the pressure receiving section is executed. Further, in this device, the temperature of the heater at the time of execution of the deposit restraint control is controlled to a temperature equal to or lower than a specific temperature (an upper limit temperature) within a range of 700 to 900°C. If deposit restraint control is executed, adhesion of deposit to the pressure receiving section can be restrained. Further, if the temperature of the heater is controlled to a temperature equal to or lower than the upper limit temperature, reduction in the life of the heating element by execution of deposit restraint control also can be restrained.
  • start time control with the objective of improving start stability of an internal combustion engine is executed, and thereafter, deposit restraint control with the objective of restraining adhesion of deposit to the pressure receiving section
  • Patent Literature 1 Japanese Patent Laid-Ope No. 2009-222031
  • Patent Literature 2 Japanese Patent Laid-Open No. 201 1-74809
  • Patent Literature 3 Japanese Patent Laid-Open No. 2009-203938
  • the deposit which accumulates between a cylinder head and a pressure receiving section needs to be decomposed by increasing the temperature of a heater. This is because once the deposit accumulates, removal thereof becomes difficult. Therefore, in the device of Patent Literature 1 , reduction in the life of the heating element as a result of repetition of increase of the temperature of the heater is feared.
  • the temperature of the heater at the time of deposit restraint control can be controlled to a low temperature. However, with the control like this, deposit cannot be decomposed when the deposit actually accumulates.
  • an object of the present invention is to make restraint of adhesion of deposit to between a cylinder head of an internal combustion engine where a glow plug-integrated type cylinder pressure sensor is incorporated and a pressure receiving section of the cylinder pressure sensor, and removal of accumulating deposit compatible.
  • a first aspect of the present invention is a control device for an internal combustion engine.
  • the internal combustion engine include a glow plug-integrated type cylinder pressure sensor in which a pressure receiving section of the cylinder pressure sensor that detects pressure in a cylinder of the internal combustion engine is configured as a heater containing a heating element.
  • the control device includes means for performing start time control of controlling a temperature of the heater to be in a predetermined temperature range by performing energization to the heating element at a time of start of the internal combustion engine.
  • control device includes means for, apart from the start time control, depositing prevention control of controlling a temperature around the heater to be in a first temperature range lower than the predetermined temperature range by performing energization to the heating element, deposit decomposition control of controlling the temperature range around the heater to be in a second temperature range that is higher than the first temperature by performing energization to the heating element are selectively performed.
  • the first temperature range may be a temperature range that is set in advance as a temperature range in which a liquid adhering to an inner circumferential wall of a glow hole between the heater and a cylinder head, and containing unburned fuel is vaporizable.
  • the second temperature range may be a temperature range that is set in advance as a temperature range in which deposit accumulating on the inner circumferential wall is decomposable.
  • a lower limit of the first temperature range may be 180°C.
  • an upper limit of the first temperature range may be 380°C.
  • the depositing prevention control may be executed conditionally upon an amount of unburned fuel that remains in the cylinder being equal to or larger than a predetermined amount.
  • the deposit decomposition control may be executed conditionally upon an amount of deposit that accumulates on an inner circumferential wall of a glow hole between the heater and a cylinder head being equal to or larger than a predetermined amount.
  • the depositing prevention control and the deposit decomposition control can be selectively performed.
  • the depositing prevention control controls the temperature around the heater of the glow plug to be in the first temperature range lower than the predetermined temperature range and can prevent deposit from being generated.
  • the deposit decomposition control controls the temperature around the heater to be in the second temperature range that is higher than the first temperature, and can decompose and remove deposit even if the deposit is generated. Consequently, according to the present invention, restraint of adherence of deposit to between the cylinder head and the pressure receiving section of the cylinder pressure sensor, and removable of the accumulating deposit can be made compatible.
  • the liquid adhering to the inner circumferential wall of the glow hole between the heater and a cylinder head, and containing unburned fuel can be evaporated and removed by the depositing prevention control. Further, the deposit accumulating on the inner circumferential wall can be decomposed and removed by the deposit decomposition control.
  • the lower limit of the first temperature range can be set at 180°C.
  • the upper limit of the first temperature range can be set at 380°C.
  • the upper limit and the lower limit of the first temperature range are based on a distillation characteristic curve of light oil and a boiling point of a main component of base oil of engine oil. Consequently, according to the present invention, generation of deposit can be favorably prevented by the depositing prevention control.
  • the depositing prevention control is executed conditionally upon the amount of the unburned fuel that remains in the cylinder being equal to or larger than the predetermined amount. Namely, when the amount of the unburned fuel remaining in the cylinder is less than the predetermined amount, execution of the depositing prevention control is prohibited. Accordingly, worsening of fuel economy and increase in emission of CO2 accompanying execution of the depositing prevention control can be kept to a minimum.
  • the deposit decomposition control is executed conditionally upon the amount of the deposit that accumulates on the im er circumferential wall of the glow hole between the heater and the cylinder head being equal to or larger than the predetermined amount. That is to say, when the estimated amount of the deposit that accumulates on the inner circumferential wall of the glow hole between the heater and the cylinder head is less than the predetermined amount, execution of the deposit decomposition control is prohibited. Accordingly, worsening of fuel economy and increase in emission of CO2 accompanying execution of the deposit decomposition control can be kept to a minimum.
  • Figure 1 is a view schematically showing a system configuration of the embodiment of the present invention.
  • Figure 2 is a view showing a tip end portion of a CPS and a peripheral portion thereof.
  • Figure 3 is a view explaining a generation process of deposit.
  • Figure 4 is a diagram showing a ratio of components included in deposit.
  • Figure 5 is a diagram showing a distillation characteristic curve of light oil.
  • Figure 6 is a flowchart showing an energization control routine that is executed by an
  • Figure 1 is a view schematically showing a system configuration of the embodiment of the present invention.
  • the system of the present embodiment includes a diesel engine 10 as an internal combustion engine that is mounted on a vehicle or the like.
  • a cylinder 12 of the diesel engine 10 is provided with a piston 14 that slides in the cylinder 12.
  • a cylinder head 16 is disposed over the cylinder 12.
  • a combustion chamber 18 is defined by a bore wall surface of the cylinder 12, a top surface of the piston 14 and a bottom surface of the cylinder head 16.
  • an injector 20 that directly injects light oil that is fuel into the combustion chamber 18 is fitted.
  • the diesel engine 10 of the present embodiment is a compression-ignition type multiple cylinder engine that causes fuel which is injected from the injector 20 to ignite spontaneously in the combustion chamber 18 in a compressed state.
  • the diesel engine 10 may be a single-cylinder engine.
  • a cylinder pressure sensor (hereinafter, also called “CPS”) 22 that will be described later is also fitted.
  • the injector 20 and the CPS 22 are fitted in each of the combustion chambers 18.
  • the system of the present embodiment includes an ECU (Electronic Control Unit) 30.
  • ECU Electronic Control Unit
  • various sensors for example, a crank angle sensor that detects an engine speed, an air flow meter that detects an intake air amount, a temperature sensor that detects an engine water temperature and the like
  • various actuators such as the injector 20 are electrically connected.
  • the ECU 30 executes various kinds of control relating to an operation of the diesel engine 10 besides start time control, prevention heating control and decomposition heating control that will be described later, by executing predetermined programs based on input information from various sensors, and operating the various actuators and the like.
  • FIG. 2 is a view showing a tip end portion of the CPS 22 and a peripheral portion thereof.
  • the CPS 22 includes a heater 24 in a rod shape to be a pressure receiving section and a sensing section 26, and is inserted into a glow hole (screw hole) 28 formed in the cylinder head 16.
  • a tip end side thereof protrudes to the combustion chamber 18, and a base end side thereof is fixed to the cylinder head 16.
  • the sensing section 26 is electrically connected to the heater 24 via a center shaft (not illustrated), and is electrically connected to the ECU 30.
  • the CPS 22 is a glow plug-integrated type cylinder pressure sensor.
  • the heater 24 is configured to be movable in an axial direction thereof (the arrow direction in Figure 2). When the heater 24 receives pressure in the combustion chamber 18 (hereinafter, also called “cylinder pressure"), the heater 24 moves in the axial direction of the heater 24 in response to the pressure.
  • the sensing section 26 is configured to detect displacement amounts of the heater 24 and the center shaft. For the sensing section 26, a piezoelectric element that generates electricity corresponding to the displacement amount, or a strain gauge that measures the displacement amount as a strain amount are used, for example.
  • the displacement amount detected by the sensing section 26 corresponds to the cylinder pressure, and the detection value is transmitted to the ECU 30.
  • the CPS 22 functions as a glow plug, when a heating element (not illustrated) contained in a tip end portion of the heater 24 is energized.
  • a heating element not illustrated
  • the heater 24 is heated (glow heating), whereby the temperature in the combustion chamber 18 increases.
  • One kind of energization control for the heating element is start time control. At an engine start time, the engine water temperature is low, the temperature in the combustion chamber 18 is also low, and therefore, even if the air in the combustion chamber 18 is compressed, the temperature in the combustion chamber 18 does not sometimes reach an ignition temperature.
  • the start time control is performed with the objective of avoiding this.
  • an energization amount (hereinafter, also called “a glow energization amount”) which is applied to the heating element is regulated, and the temperature of the heater 24 is controlled to a predetermined temperature range (more specifically, 700°C to 900°C). At a point of time when the engine water temperature reaches a predetermined time, the start time control is ended.
  • FIG. 3 is a view explaining a generation process of deposit.
  • solid particles 32 of soot and the like float in the combustion chamber 18.
  • HC in a liquid state and liquid particles 34 of engine oil and the like are also present in the combustion chamber 18.
  • a mixture gas 36 including the solid particles 32, HC in a gaseous state, the engine oil and the like is also present.
  • an amount of the engine oil which is present in the combustion chamber 18 is smaller as compared with the amount of HC. Therefore, in the following explanation, the HC in the liquid state also can be considered as the liquid particles 34, and a gas including the solid particles 32 and the HC in the gaseous state also can be considered as the mixture gas 36.
  • the liquid particle 34 contacts and adheres to an inner wall of the combustion chamber 18. Meanwhile, the solid particle 32 does not adhere to the inner wall of the combustion chamber 18 alone, but adheres to the inner wall of the combustion chamber 18 together with the liquid particle 34. That is to say, the liquid particle 34 adheres to the inner wall of the combustion chamber 18, the solid particle 32 adheres to the liquid particle 34 adhering thereto, whereby the solid particle 32 adheres to the inner wall of the combustion chamber 18. Alternatively, the liquid particle 34 adheres to the inner wall of the combustion chamber 18 while capturing the solid particle 32, and thus the solid particle 32 adheres to the inner wall of the combustion chamber 18.
  • the solid particle 32 and the liquid particle 34 also adhere to the tip end portion of the heater 24.
  • the reason thereof is that the tip end portion of the heater 24 protrudes into the combustion chamber 18.
  • the solid particle 32 and the liquid particle 34 also adhere to an inner circumferential wall of the glow hole 28.
  • the reason thereof is that the mixture gas 36 flows into the glow hole 28 from a gap between the heater 24 and the cylinder head 16 (see the arrow in Figure 3), and further, the HC and the engine oil included in the mixture gas 36 are cooled in the glow hole 28.
  • Viscosity of the adhering liquid particle 34 increases as a result that the adhering state lasts for a long time.
  • the reason thereof is considered to be the fact that the adhering liquid particle 34 changes into an oxide with a lapse of the adhering time, and functions as a binder that bonds the solid particles 32 which adhere together with the liquid particle 34.
  • the viscosity of the adhering liquid particles 34 becomes high, a fixing force thereof to the place where the liquid particles 34 adhere becomes strong, and the liquid particles 34 change into deposit 38. As a result, the deposit 38 accumulates on a periphery of the heater 24.
  • Figure 4 is a diagram showing a ratio of components included in deposit.
  • Figure 4 is created based on a TG- DTA (differential thermo-thermogravimetry) measurement result.
  • the present inventors estimate that a loss in quantity at a room temperature to 350°C is derived from base oil of engine oil and light oil. The estimation is based on a distillation characteristic curve of the light oil and a boiling point of a main component of the base oil.
  • Figure 5 is a diagram showing a distillation characteristic curve of light oil. As shown in Figure 5, a distillation amount of the light oil, which is 0% at approximately 175°C reaches 100% at approximately 365°C.
  • the HC component in the light oil starts to evaporate at approximately 175°C, and is completely evaporated at a temperature up to approximately 365°C.
  • the present inventors estimate that a loss in quantity from 500°C to 700°C is derived from carbides (namely, soot) of the light oil and the base oil. The estimation is based on a thermal decomposition temperature of soot. Further, a loss in quantity in a remaining temperature range, namely, at 350°C to 500°C is derived from oxides of the light oil and the base oil.
  • the energization control which is performed in the present embodiment refers to prevention heating control and decomposition heating control.
  • the prevention heating control is performed with the objective of vaporizing the liquid particles 34 which adhere to the inner circumferential wall of the glow hole 28.
  • a glow energization amount is regulated, and a temperature of the heater 24 is controlled so that a temperature in the glow hole 28 becomes 180°C to 380°C.
  • the main components of the light oil and the base oil evaporate at approximately 175°C to approximately 365°C. Accordingly, even when the liquid particles 34 adhere to the inner circumferential wall of the glow hole 28, the liquid particles 34 can be vaporized and removed by the prevention heating control.
  • the prevention heating control deposit can be prevented from being generated. Note that the reason why the prevention heating control is performed at 180°C to 380°C whereas the main components of the light oil and the base oil evaporate at approximately 175°C to approximately 365°C experimentally is that various components existing in the glow hole 28 are taken into consideration.
  • the decomposition heating control is performed with the objective of decomposing a binder component of the deposit which accumulates on the inner circumferential wall of the glow hole 28.
  • the glow energization amount is regulated, and the temperature of the heater 24 is controlled so that the temperature in the glow hole 28 becomes 400°C to 500°C.
  • the oxides in the light oil and the base oil are decomposed at 350°C to 500°C. Accordingly, even when the liquid particle 34 adhering to the inner circumferential wall of the glow hole 28 changes into oxides, the oxides can be decomposed and removed by the decomposition heating control. Namely, according to the decomposition heating control, even if deposit is generated, the deposit can be decomposed and removed. Note that the reason why a lower limit temperature of the decomposition heating temperature is set at 400°C while the oxides of the light oil and the base oil are decomposed at 350°C to 500°C experimentally is that various components existing in the glow hole 28 are taken into
  • the prevention heating control and the decomposition heating control are selectively performed after the start time control is ended. More specifically, the prevention heating control is performed when the function of the CPS 22 as the pressure sensor is normal. On the other hand, the decomposition heating control is performed when the function is abnormal. If the light oil and the base oil only adhere to the inner circumferential wall of the glow hole 28, an influence which is exerted on the function is small. However, when deposit is generated and accumulates, the function is reduced. Therefore, when the function falls short of a fixed reference, the function is determined as abnormal, and the decomposition heating control is executed. Here, as the control temperature around the heater 24 at the time of energization control becomes higher, the glow energization amount needs to be increased.
  • the decomposition heating control in which the control temperature is high can be carried out only in an urgent case. Therefore, the aforementioned effect can be exhibited while occurrence of the problems accompanying execution of the energization control is kept to a minimum.
  • a temperature of a deepest part of the glow hole 28 is desirably controlled to be in the
  • the temperature in the glow hole 28 is not always uniform, and in the part farther away from the combustion chamber 18 (toward the base end side from the tip end side of the heater 24), the temperature in the glow hole 28 becomes lower. Further, the reason thereof is that a support section of the heater 24 is located in the deepest part, and when deposit accumulates, a spring constant of the support section changes and a detection error becomes larger.
  • the aforementioned target temperature ranges are desirably changed in accordance with the operation state of the diesel engine 10.
  • the reason thereof is that when the engine performs a high load operation, the temperature in the glow hole 28 is higher as compared with a case in which a low load operation is performed, and the temperature can reach the aforementioned target temperature ranges relatively easily. Accordingly, for example, when the load of the diesel engine 10 is high, the above described target temperature ranges are desirably changed to low temperature ranges as compared with the case in which the load of the diesel engine 10 is low.
  • Figure 6 is a flowchart showing an energization control routine that is executed by the ECU 30 in the embodiment. Note that the routine shown in Figure 6 is repeatedly executed regularly immediately after the start of the diesel engine 10.
  • step S10 it is determined whether or not the start time control is ended, first (step S10). More specifically, it is determined whether or not the engine water temperature is equal to or higher than a predetermined temperature. When it is determined that the engine water temperature is lower than the predetermined temperature, the present routine is ended in order to wait for an end of the start time control. When it is determined that the engine water temperature is equal to or higher than the predetermined temperature, it can be determined that the start time control is ended, and therefore, the flow proceeds to step SI 2. Note that the start time control is executed in a different routine from the present routine.
  • step SI 2 it is determined whether or not permission conditions of glow heating are established. For example, if glow heating is performed when the diesel engine 10 performs a low-temperature combustion operation, smoke increases. In such a case, it is determined that the permission conditions are not established, and the present routine is ended.
  • step S 14 it is determined whether or not the function of the CPS 22 as the pressure sensor is normal (step S 14).
  • the determination is performed as follows more specifically. First, a heat generation amount parameter is calculated from an output (namely, the cylinder pressure) of the CPS 22 at a predetermined crank angle. Next, a difference between the calculated heat generation amount parameter and a reference heat generation amount parameter is calculated. Subsequently, the difference and a threshold value (a first threshold value) that is set in advance are compared. When the difference is smaller than the first threshold value, the CPS 22 is determined as normal. When the difference is equal to or larger than the first threshold value, the CPS 22 is determined as abnormal.
  • an arithmetic expression for calculating the heat generation amount parameter from the cylinder pressure, the first threshold value and the like are stored in the ECU 30 in advance. Note that the determination of the present step also can be performed based on a known method different from the aforementioned method.
  • step SI 6 determination concerning an exhaust amount of HC is performed. More specifically, the determination is performed as follows. First, the amount of HC which remains in the combustion chamber 18 is calculated based on the operation state of the diesel engine 10. For example, the HC residual amount can be calculated by using the methods described in Japanese Patent Laid-Open No.
  • the calculated HC residual amount and a threshold value (an upper limit permission value) that is set in advance are compared.
  • the HC residual amount is less than the upper limit permission value, it can be determined that the possibility that deposit is generated in the combustion chamber 18 is low, and therefore, the present routine is ended.
  • the HC residual amount is equal to or larger than the upper limit permission amount, it is conceivable that the possibility that HC adheres to the inner circumferential wall of the glow hole 28 is high. Therefore, in this case, the flow proceeds to step SI 8, and the prevention heating control is executed.
  • an arithmetic expression for calculating the HC residual amount from the operation state of the diesel engine 10, the upper limit permission value and the like are stored in the ECU 30 in advance.
  • step S20 determination concerning an accumulation amount of deposit is performed (step S20). More specifically, the determination is performed as follows. First, the difference calculated in step S14 and a threshold value (a second threshold value) set in advance are compared. Here, the difference is correlated with the accumulation amount of deposit which accumulates on the inner circumferential wall of the glow hole 28, which means that the larger the difference, the larger the accumulation amount. Further, the second threshold value is a value larger than the first threshold value. When the difference is smaller than the second threshold value, it can be determined that the possibility of causing a serious problem to the pressure sensor function of the CPS 22 is low, and therefore, the present routine is ended.
  • the flow proceeds to step S22, and the decomposition heating control is executed. That is to say, it is determined that the amount of the deposit accumulating on the inner circumferential wall of the glow hole 28 is equal to or larger than the predetermined amount, based on the fact that the difference is equal to or larger than the second threshold value.
  • the second threshold value is stored in the ECU 30 in advance.
  • the prevention heating control and the decomposition heating control can be selectively executed (steps S 18 and S22). Accordingly, deposit can be prevented from being generated, and even if deposit is generated, the deposit can be decomposed and removed. Further, when the HC residual amount is smaller than the upper limit permission value, execution of the prevention heating control is prohibited (step S16).
  • step S20 when the difference calculated in step S 14 is smaller than the second threshold value, execution of the decomposition heating control is prohibited (step S20). Accordingly, worsening of fuel economy and increase in emission of CC accompanying execution of the energization control can be kept to a minimum. The life of the heating element also can be increased.
  • the prevention heating control it is determined whether or not the prevention heating control can be executed based on the HC residual amount in step S 16 in Figure 6.
  • the reason thereof is based on the fact that the main cause of deposit is the liquid particles 34 including HC.
  • coexistence of the liquid particles 34 and the solid particles 32 is needed for generation of deposit as already described.
  • the determination is preferably performed not only based on the HC residual amount but also with the residual amount of the solid particles 32 taken into consideration. By also taking the residual amount of the solid particles 32 into consideration, it can be determined whether or not the prevention heating control can be executed more properly.
  • step S16 in Figure 6 it is determined whether or not the prevention heating control can be executed in step S16 in Figure 6, or it is determined whether or not the heating decomposition control can be executed in step S20 in Figure 6.
  • these determinations can be also omitted. Namely, when the CPS 22 is determined as normal in step S 14 in Figure 6, the prevention heating control may be executed. Further, when the CPS 22 is determined as abnormal in step S14 in Figure 6, the heating decomposition control may be immediately executed.
  • the difference between the heat generation amount parameter and the reference heat generation amount parameter is compared with the first threshold value and the second threshold value respectively in both step S14 and step S16 in Figure 6, but for them, different parameters may be respectively used.
  • step S 14 abnormality determination of the CPS 22 is performed by different parameters
  • step S20 the difference between the heat generation amount parameter and the reference heat generation parameter may be used as described above.
  • step S20 in Figure 6 the amount of the deposit accumulating on the inner circumferential wall of the glow hole 28 is estimated based on the difference between the heat generation amount parameter and the reference heat generation amount parameter, but this may be estimated from an arithmetic operation and a map based on various engine parameters. Namely, during an operation of the diesel engine, the amount of the deposit accumulating on the inner circumferential wall of the glow hole 28 is calculated and integrated, and when the integrated value thereof exceeds a predetermined threshold value, the heating decomposition control may be executed. Note that the integrated value may be subjected to subtraction or the like by execution of the prevention heating control.
  • the prevention heating control corresponds to “depositing prevention control” in the above described first aspect of the present invention
  • the heating decomposition control corresponds to “deposit decomposition control” in the same aspect of the present invention, respectively.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

Prevention heating control is performed with an objective of evaporating light oil and the like adhering to an inner circumferential wall of a glow hole. In the prevention heating control, a temperature of a heater is controlled so that a temperature in the glow hole becomes 180 °C to 380 °C. Decomposition heating control is performed with an objective of decomposing a binder component of the deposit accumulating on the surface and the inner circumferential wall. In the decomposition heating control, the temperature of the heater is controlled so that the temperature in the glow hole becomes 400 °C to 500 °C. The prevention heating control and the decomposition heating control are selectively performed after an end of start time control. In the start time control, a temperature around the heater is controlled to 700 °C to 900 °C.

Description

Description
Title of Invention
CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE
Technical Field
[0001]
The present invention relates to a control device for an internal combustion engine.
More specifically, the invention relates to a control device for an internal combustion engine using a glow plug-integrated type cylinder pressure sensor.
Background Art
[0002]
Conventionally, there has been known a glow plug-integrated type cylinder pressure sensor in which the pressure receiving section of the cylinder pressure sensor which detects the cylinder pressure of an internal combustion engine is configured by a heater of a glow plug containing a heating element. Concerning the cylinder pressure sensor like this, Patent
Literature 1 , for example, discloses the device which estimates the amount of deposit that accumulates between the cylinder head of the internal combustion engine and the pressure receiving section when the internal combustion engine is in a predetermined operation state, and controls energization to the heating element based on the estimated amount. When deposit accumulates between the cylinder head and the pressure receiving section, sliding resistance of the pressure receiving section occurs, and detection precision of the cylinder pressure sensor is reduced. In this regard, according to the device of Patent Literature 1 , energization to the heating element can be controlled based on the estimated amount. Accordingly, even if deposit accumulates between the cylinder head and the pressure receiving section, the temperature of the heater is increased, and thereby the deposit can be decomposed and removed.
[0003]
Further, for example, Patent Literature 2 discloses the device which performs energization control to a heating element with two different objectives. More specifically, in this device, start time control with the objective of improving start stability of an internal combustion engine is executed, and thereafter, deposit restraint control with the objective of restraining adhesion of deposit to the pressure receiving section is executed. Further, in this device, the temperature of the heater at the time of execution of the deposit restraint control is controlled to a temperature equal to or lower than a specific temperature (an upper limit temperature) within a range of 700 to 900°C. If deposit restraint control is executed, adhesion of deposit to the pressure receiving section can be restrained. Further, if the temperature of the heater is controlled to a temperature equal to or lower than the upper limit temperature, reduction in the life of the heating element by execution of deposit restraint control also can be restrained.
Citation List
Patent Literature
[0004]
[Patent Literature 1] Japanese Patent Laid-Ope No. 2009-222031
[Patent Literature 2] Japanese Patent Laid-Open No. 201 1-74809
[Patent Literature 3] Japanese Patent Laid-Open No. 2009-203938
Summary of Invention
Technical Problem
[0005]
Incidentally, the deposit which accumulates between a cylinder head and a pressure receiving section needs to be decomposed by increasing the temperature of a heater. This is because once the deposit accumulates, removal thereof becomes difficult. Therefore, in the device of Patent Literature 1 , reduction in the life of the heating element as a result of repetition of increase of the temperature of the heater is feared. In this regard, according to the device of Patent Literature 2, the temperature of the heater at the time of deposit restraint control can be controlled to a low temperature. However, with the control like this, deposit cannot be decomposed when the deposit actually accumulates.
[0006]
The present invention is made in the light of the aforementioned problem. Namely, an object of the present invention is to make restraint of adhesion of deposit to between a cylinder head of an internal combustion engine where a glow plug-integrated type cylinder pressure sensor is incorporated and a pressure receiving section of the cylinder pressure sensor, and removal of accumulating deposit compatible. Solution to Problem
[0007]
A first aspect of the present invention is a control device for an internal combustion engine. The internal combustion engine include a glow plug-integrated type cylinder pressure sensor in which a pressure receiving section of the cylinder pressure sensor that detects pressure in a cylinder of the internal combustion engine is configured as a heater containing a heating element. The control device includes means for performing start time control of controlling a temperature of the heater to be in a predetermined temperature range by performing energization to the heating element at a time of start of the internal combustion engine. Further, the control device includes means for, apart from the start time control, depositing prevention control of controlling a temperature around the heater to be in a first temperature range lower than the predetermined temperature range by performing energization to the heating element, deposit decomposition control of controlling the temperature range around the heater to be in a second temperature range that is higher than the first temperature by performing energization to the heating element are selectively performed.
[0008]
Further, according to a second aspect of the present invention, in the first aspect, the first temperature range may be a temperature range that is set in advance as a temperature range in which a liquid adhering to an inner circumferential wall of a glow hole between the heater and a cylinder head, and containing unburned fuel is vaporizable. In the second aspect, the second temperature range may be a temperature range that is set in advance as a temperature range in which deposit accumulating on the inner circumferential wall is decomposable.
[0009]
Further, according to a third aspect of the present invention, in the first or the second aspect, a lower limit of the first temperature range may be 180°C.
[0010]
Further, according to a fourth aspect of the present invention, in any one of the first to the third aspects, an upper limit of the first temperature range may be 380°C.
[0011]
Further, according to a fifth aspect of the present invention, in any one of the first to the fourth aspects, the depositing prevention control may be executed conditionally upon an amount of unburned fuel that remains in the cylinder being equal to or larger than a predetermined amount.
[0012]
Further, according to a sixth aspect of the present invention, in any one of the first to the fifth aspects, the deposit decomposition control may be executed conditionally upon an amount of deposit that accumulates on an inner circumferential wall of a glow hole between the heater and a cylinder head being equal to or larger than a predetermined amount.
Advantageous Effect of Invention
[0013]
According to the first aspect of the present invention, apart from the start time control, the depositing prevention control and the deposit decomposition control can be selectively performed. The depositing prevention control controls the temperature around the heater of the glow plug to be in the first temperature range lower than the predetermined temperature range and can prevent deposit from being generated. The deposit decomposition control controls the temperature around the heater to be in the second temperature range that is higher than the first temperature, and can decompose and remove deposit even if the deposit is generated. Consequently, according to the present invention, restraint of adherence of deposit to between the cylinder head and the pressure receiving section of the cylinder pressure sensor, and removable of the accumulating deposit can be made compatible.
[0014]
According to the second aspect of the present invention, the liquid adhering to the inner circumferential wall of the glow hole between the heater and a cylinder head, and containing unburned fuel can be evaporated and removed by the depositing prevention control. Further, the deposit accumulating on the inner circumferential wall can be decomposed and removed by the deposit decomposition control.
[0015]
According to the third aspect of the present invention, the lower limit of the first temperature range can be set at 180°C. According to the fourth aspect of the present invention, the upper limit of the first temperature range can be set at 380°C. The upper limit and the lower limit of the first temperature range are based on a distillation characteristic curve of light oil and a boiling point of a main component of base oil of engine oil. Consequently, according to the present invention, generation of deposit can be favorably prevented by the depositing prevention control.
[0016]
According to the fifth aspect of the present invention, the depositing prevention control is executed conditionally upon the amount of the unburned fuel that remains in the cylinder being equal to or larger than the predetermined amount. Namely, when the amount of the unburned fuel remaining in the cylinder is less than the predetermined amount, execution of the depositing prevention control is prohibited. Accordingly, worsening of fuel economy and increase in emission of CO2 accompanying execution of the depositing prevention control can be kept to a minimum.
[0017]
According to the sixth aspect of the present invention, the deposit decomposition control is executed conditionally upon the amount of the deposit that accumulates on the im er circumferential wall of the glow hole between the heater and the cylinder head being equal to or larger than the predetermined amount. That is to say, when the estimated amount of the deposit that accumulates on the inner circumferential wall of the glow hole between the heater and the cylinder head is less than the predetermined amount, execution of the deposit decomposition control is prohibited. Accordingly, worsening of fuel economy and increase in emission of CO2 accompanying execution of the deposit decomposition control can be kept to a minimum.
Brief Description of Drawings
[0018]
[Figure 1] Figure 1 is a view schematically showing a system configuration of the embodiment of the present invention.
[Figure 2] Figure 2 is a view showing a tip end portion of a CPS and a peripheral portion thereof.
[Figure 3] Figure 3 is a view explaining a generation process of deposit.
[Figure 4] Figure 4 is a diagram showing a ratio of components included in deposit.
[Figure 5] Figure 5 is a diagram showing a distillation characteristic curve of light oil.
[Figure 6] Figure 6 is a flowchart showing an energization control routine that is executed by an
ECU in the embodiment.
Description of Embodiment [0019]
Hereinafter, with reference to Figure 1 to Figure 6, an embodiment of the present invention will be described.
[0020]
[Explanation of system configuration]
Figure 1 is a view schematically showing a system configuration of the embodiment of the present invention. As shown in Figure 1 , the system of the present embodiment includes a diesel engine 10 as an internal combustion engine that is mounted on a vehicle or the like. A cylinder 12 of the diesel engine 10 is provided with a piston 14 that slides in the cylinder 12. A cylinder head 16 is disposed over the cylinder 12. A combustion chamber 18 is defined by a bore wall surface of the cylinder 12, a top surface of the piston 14 and a bottom surface of the cylinder head 16.
[0021]
In the cylinder head 16, an injector 20 that directly injects light oil that is fuel into the combustion chamber 18 is fitted. The diesel engine 10 of the present embodiment is a compression-ignition type multiple cylinder engine that causes fuel which is injected from the injector 20 to ignite spontaneously in the combustion chamber 18 in a compressed state.
However, the diesel engine 10 may be a single-cylinder engine. In the cylinder head 16, a cylinder pressure sensor (hereinafter, also called "CPS") 22 that will be described later is also fitted. The injector 20 and the CPS 22 are fitted in each of the combustion chambers 18.
[0022]
Further, the system of the present embodiment includes an ECU (Electronic Control Unit) 30. To an input side of the ECU 30, various sensors (for example, a crank angle sensor that detects an engine speed, an air flow meter that detects an intake air amount, a temperature sensor that detects an engine water temperature and the like) necessary for control of the diesel engine 10, besides the CPS 22 are electrically connected. On the other hand, to an output side of the ECU 30, various actuators such as the injector 20 are electrically connected. The ECU 30 executes various kinds of control relating to an operation of the diesel engine 10 besides start time control, prevention heating control and decomposition heating control that will be described later, by executing predetermined programs based on input information from various sensors, and operating the various actuators and the like.
[0023] [Explanation of CPS 22]
Figure 2 is a view showing a tip end portion of the CPS 22 and a peripheral portion thereof. As shown in Figure 2, the CPS 22 includes a heater 24 in a rod shape to be a pressure receiving section and a sensing section 26, and is inserted into a glow hole (screw hole) 28 formed in the cylinder head 16. In the heater 24, a tip end side thereof protrudes to the combustion chamber 18, and a base end side thereof is fixed to the cylinder head 16. The sensing section 26 is electrically connected to the heater 24 via a center shaft (not illustrated), and is electrically connected to the ECU 30.
[0024]
The CPS 22 is a glow plug-integrated type cylinder pressure sensor. The heater 24 is configured to be movable in an axial direction thereof (the arrow direction in Figure 2). When the heater 24 receives pressure in the combustion chamber 18 (hereinafter, also called "cylinder pressure"), the heater 24 moves in the axial direction of the heater 24 in response to the pressure. The sensing section 26 is configured to detect displacement amounts of the heater 24 and the center shaft. For the sensing section 26, a piezoelectric element that generates electricity corresponding to the displacement amount, or a strain gauge that measures the displacement amount as a strain amount are used, for example. The displacement amount detected by the sensing section 26 corresponds to the cylinder pressure, and the detection value is transmitted to the ECU 30.
[0025]
The CPS 22 functions as a glow plug, when a heating element (not illustrated) contained in a tip end portion of the heater 24 is energized. When the heating element is energized, the heater 24 is heated (glow heating), whereby the temperature in the combustion chamber 18 increases. One kind of energization control for the heating element is start time control. At an engine start time, the engine water temperature is low, the temperature in the combustion chamber 18 is also low, and therefore, even if the air in the combustion chamber 18 is compressed, the temperature in the combustion chamber 18 does not sometimes reach an ignition temperature. The start time control is performed with the objective of avoiding this. In the start time control, an energization amount (hereinafter, also called "a glow energization amount") which is applied to the heating element is regulated, and the temperature of the heater 24 is controlled to a predetermined temperature range (more specifically, 700°C to 900°C). At a point of time when the engine water temperature reaches a predetermined time, the start time control is ended.
[0026]
[Feature of embodiment]
Incidentally, when fuel is combusted in the combustion chamber 18, particles of soot and the like sometimes arise in the combustion chamber 18. Further, in the combustion chamber 18, unburned fuel (hereinafter, also called "HC"), engine oil and the like sometimes remain. Soot, HC and engine oil sometimes change to be deposit around the CPS 22. Figure 3 is a view explaining a generation process of deposit. As shown in Figure 3, solid particles 32 of soot and the like float in the combustion chamber 18. HC in a liquid state and liquid particles 34 of engine oil and the like are also present in the combustion chamber 18. A mixture gas 36 including the solid particles 32, HC in a gaseous state, the engine oil and the like is also present. Note that in general, an amount of the engine oil which is present in the combustion chamber 18 is smaller as compared with the amount of HC. Therefore, in the following explanation, the HC in the liquid state also can be considered as the liquid particles 34, and a gas including the solid particles 32 and the HC in the gaseous state also can be considered as the mixture gas 36.
[0027]
The liquid particle 34 contacts and adheres to an inner wall of the combustion chamber 18. Meanwhile, the solid particle 32 does not adhere to the inner wall of the combustion chamber 18 alone, but adheres to the inner wall of the combustion chamber 18 together with the liquid particle 34. That is to say, the liquid particle 34 adheres to the inner wall of the combustion chamber 18, the solid particle 32 adheres to the liquid particle 34 adhering thereto, whereby the solid particle 32 adheres to the inner wall of the combustion chamber 18. Alternatively, the liquid particle 34 adheres to the inner wall of the combustion chamber 18 while capturing the solid particle 32, and thus the solid particle 32 adheres to the inner wall of the combustion chamber 18.
[0028]
The solid particle 32 and the liquid particle 34 also adhere to the tip end portion of the heater 24. The reason thereof is that the tip end portion of the heater 24 protrudes into the combustion chamber 18. Further, the solid particle 32 and the liquid particle 34 also adhere to an inner circumferential wall of the glow hole 28. The reason thereof is that the mixture gas 36 flows into the glow hole 28 from a gap between the heater 24 and the cylinder head 16 (see the arrow in Figure 3), and further, the HC and the engine oil included in the mixture gas 36 are cooled in the glow hole 28.
[0029]
Viscosity of the adhering liquid particle 34 increases as a result that the adhering state lasts for a long time. The reason thereof is considered to be the fact that the adhering liquid particle 34 changes into an oxide with a lapse of the adhering time, and functions as a binder that bonds the solid particles 32 which adhere together with the liquid particle 34. When the viscosity of the adhering liquid particles 34 becomes high, a fixing force thereof to the place where the liquid particles 34 adhere becomes strong, and the liquid particles 34 change into deposit 38. As a result, the deposit 38 accumulates on a periphery of the heater 24.
[0030]
The viscosity of the liquid particles 34 which adhere to the inner circumferential wall of the glow hole 28, of the periphery of the heater 24, becomes high, resistance occurs to slide of the heater 24 as the pressure receiving section. When the deposit 38 accumulates on the inner circumferential wall of the glow hole 28, even more resistance occurs, and in such a case, the detection precision of the CPS 22 as a pressure sensor reduces. Therefore, in the present embodiment, energization control to the heating element is performed based on new knowledge which is obtained by the present inventors.
[0031]
The knowledge will be described with reference to Figure 4 and Figure 5. Figure 4 is a diagram showing a ratio of components included in deposit. Figure 4 is created based on a TG- DTA (differential thermo-thermogravimetry) measurement result. As shown in Figure 4, the present inventors estimate that a loss in quantity at a room temperature to 350°C is derived from base oil of engine oil and light oil. The estimation is based on a distillation characteristic curve of the light oil and a boiling point of a main component of the base oil. Figure 5 is a diagram showing a distillation characteristic curve of light oil. As shown in Figure 5, a distillation amount of the light oil, which is 0% at approximately 175°C reaches 100% at approximately 365°C. That is to say, the HC component in the light oil starts to evaporate at approximately 175°C, and is completely evaporated at a temperature up to approximately 365°C. Further, the present inventors estimate that a loss in quantity from 500°C to 700°C is derived from carbides (namely, soot) of the light oil and the base oil. The estimation is based on a thermal decomposition temperature of soot. Further, a loss in quantity in a remaining temperature range, namely, at 350°C to 500°C is derived from oxides of the light oil and the base oil.
[0032]
More specifically, the energization control which is performed in the present embodiment refers to prevention heating control and decomposition heating control. The prevention heating control is performed with the objective of vaporizing the liquid particles 34 which adhere to the inner circumferential wall of the glow hole 28. In the prevention heating control, a glow energization amount is regulated, and a temperature of the heater 24 is controlled so that a temperature in the glow hole 28 becomes 180°C to 380°C. As described with Figure 5, the main components of the light oil and the base oil evaporate at approximately 175°C to approximately 365°C. Accordingly, even when the liquid particles 34 adhere to the inner circumferential wall of the glow hole 28, the liquid particles 34 can be vaporized and removed by the prevention heating control. Namely, according to the prevention heating control, deposit can be prevented from being generated. Note that the reason why the prevention heating control is performed at 180°C to 380°C whereas the main components of the light oil and the base oil evaporate at approximately 175°C to approximately 365°C experimentally is that various components existing in the glow hole 28 are taken into consideration.
[0033]
The decomposition heating control is performed with the objective of decomposing a binder component of the deposit which accumulates on the inner circumferential wall of the glow hole 28. In the decomposition heating control, the glow energization amount is regulated, and the temperature of the heater 24 is controlled so that the temperature in the glow hole 28 becomes 400°C to 500°C. As described with Figure 4, the oxides in the light oil and the base oil are decomposed at 350°C to 500°C. Accordingly, even when the liquid particle 34 adhering to the inner circumferential wall of the glow hole 28 changes into oxides, the oxides can be decomposed and removed by the decomposition heating control. Namely, according to the decomposition heating control, even if deposit is generated, the deposit can be decomposed and removed. Note that the reason why a lower limit temperature of the decomposition heating temperature is set at 400°C while the oxides of the light oil and the base oil are decomposed at 350°C to 500°C experimentally is that various components existing in the glow hole 28 are taken into
consideration. Further, the reason why an upper limit temperature is set at 500°C is to restrain power consumption by excessively increasing the temperature. [0034]
The prevention heating control and the decomposition heating control are selectively performed after the start time control is ended. More specifically, the prevention heating control is performed when the function of the CPS 22 as the pressure sensor is normal. On the other hand, the decomposition heating control is performed when the function is abnormal. If the light oil and the base oil only adhere to the inner circumferential wall of the glow hole 28, an influence which is exerted on the function is small. However, when deposit is generated and accumulates, the function is reduced. Therefore, when the function falls short of a fixed reference, the function is determined as abnormal, and the decomposition heating control is executed. Here, as the control temperature around the heater 24 at the time of energization control becomes higher, the glow energization amount needs to be increased. When the glow energization amount increases, the heat generation amount of an alternator increases, and therefore, worsening of fuel economy and increase in emission of COi are caused. In addition, reduction in the life of the heating element is also caused. In this regard, according to the present embodiment, the decomposition heating control in which the control temperature is high can be carried out only in an urgent case. Therefore, the aforementioned effect can be exhibited while occurrence of the problems accompanying execution of the energization control is kept to a minimum.
[0035]
Note that in the prevention heating control and the decomposition heating control, a temperature of a deepest part of the glow hole 28 is desirably controlled to be in the
aforementioned target temperature ranges. The reason thereof is that the temperature in the glow hole 28 is not always uniform, and in the part farther away from the combustion chamber 18 (toward the base end side from the tip end side of the heater 24), the temperature in the glow hole 28 becomes lower. Further, the reason thereof is that a support section of the heater 24 is located in the deepest part, and when deposit accumulates, a spring constant of the support section changes and a detection error becomes larger.
[0036]
Further, in the prevention heating control and the decomposition heating control, the aforementioned target temperature ranges are desirably changed in accordance with the operation state of the diesel engine 10. The reason thereof is that when the engine performs a high load operation, the temperature in the glow hole 28 is higher as compared with a case in which a low load operation is performed, and the temperature can reach the aforementioned target temperature ranges relatively easily. Accordingly, for example, when the load of the diesel engine 10 is high, the above described target temperature ranges are desirably changed to low temperature ranges as compared with the case in which the load of the diesel engine 10 is low.
[0037]
[Specific processing]
Next, with reference to Figure 6, specific processing for realizing the aforementioned function will be described. Figure 6 is a flowchart showing an energization control routine that is executed by the ECU 30 in the embodiment. Note that the routine shown in Figure 6 is repeatedly executed regularly immediately after the start of the diesel engine 10.
[0038]
In the routine shown in Figure 6, it is determined whether or not the start time control is ended, first (step S10). More specifically, it is determined whether or not the engine water temperature is equal to or higher than a predetermined temperature. When it is determined that the engine water temperature is lower than the predetermined temperature, the present routine is ended in order to wait for an end of the start time control. When it is determined that the engine water temperature is equal to or higher than the predetermined temperature, it can be determined that the start time control is ended, and therefore, the flow proceeds to step SI 2. Note that the start time control is executed in a different routine from the present routine.
[0039]
In step SI 2, it is determined whether or not permission conditions of glow heating are established. For example, if glow heating is performed when the diesel engine 10 performs a low-temperature combustion operation, smoke increases. In such a case, it is determined that the permission conditions are not established, and the present routine is ended.
[0040]
In succession to step 12, it is determined whether or not the function of the CPS 22 as the pressure sensor is normal (step S 14). The determination is performed as follows more specifically. First, a heat generation amount parameter is calculated from an output (namely, the cylinder pressure) of the CPS 22 at a predetermined crank angle. Next, a difference between the calculated heat generation amount parameter and a reference heat generation amount parameter is calculated. Subsequently, the difference and a threshold value (a first threshold value) that is set in advance are compared. When the difference is smaller than the first threshold value, the CPS 22 is determined as normal. When the difference is equal to or larger than the first threshold value, the CPS 22 is determined as abnormal. Note that an arithmetic expression for calculating the heat generation amount parameter from the cylinder pressure, the first threshold value and the like are stored in the ECU 30 in advance. Note that the determination of the present step also can be performed based on a known method different from the aforementioned method.
[0041]
When the CPS 22 is determined as normal in step S 14, determination concerning an exhaust amount of HC is performed (step SI 6). More specifically, the determination is performed as follows. First, the amount of HC which remains in the combustion chamber 18 is calculated based on the operation state of the diesel engine 10. For example, the HC residual amount can be calculated by using the methods described in Japanese Patent Laid-Open No.
2004-270471 and Japanese Patent Laid-Open No. 2009-2241. Next, the calculated HC residual amount and a threshold value (an upper limit permission value) that is set in advance are compared. When the HC residual amount is less than the upper limit permission value, it can be determined that the possibility that deposit is generated in the combustion chamber 18 is low, and therefore, the present routine is ended. When the HC residual amount is equal to or larger than the upper limit permission amount, it is conceivable that the possibility that HC adheres to the inner circumferential wall of the glow hole 28 is high. Therefore, in this case, the flow proceeds to step SI 8, and the prevention heating control is executed. Note that an arithmetic expression for calculating the HC residual amount from the operation state of the diesel engine 10, the upper limit permission value and the like are stored in the ECU 30 in advance.
[0042]
When the CPS 22 is determined as abnormal in step SI 4, determination concerning an accumulation amount of deposit is performed (step S20). More specifically, the determination is performed as follows. First, the difference calculated in step S14 and a threshold value (a second threshold value) set in advance are compared. Here, the difference is correlated with the accumulation amount of deposit which accumulates on the inner circumferential wall of the glow hole 28, which means that the larger the difference, the larger the accumulation amount. Further, the second threshold value is a value larger than the first threshold value. When the difference is smaller than the second threshold value, it can be determined that the possibility of causing a serious problem to the pressure sensor function of the CPS 22 is low, and therefore, the present routine is ended. When the difference is equal to or larger than the second threshold value, it can be determined that deposit needs to be removed urgently. Therefore, in this case, the flow proceeds to step S22, and the decomposition heating control is executed. That is to say, it is determined that the amount of the deposit accumulating on the inner circumferential wall of the glow hole 28 is equal to or larger than the predetermined amount, based on the fact that the difference is equal to or larger than the second threshold value. Note that the second threshold value is stored in the ECU 30 in advance.
[0043]
As above, according to the routine shown in Figure 6, the prevention heating control and the decomposition heating control can be selectively executed (steps S 18 and S22). Accordingly, deposit can be prevented from being generated, and even if deposit is generated, the deposit can be decomposed and removed. Further, when the HC residual amount is smaller than the upper limit permission value, execution of the prevention heating control is prohibited (step S16).
Similarly, when the difference calculated in step S 14 is smaller than the second threshold value, execution of the decomposition heating control is prohibited (step S20). Accordingly, worsening of fuel economy and increase in emission of CC accompanying execution of the energization control can be kept to a minimum. The life of the heating element also can be increased.
[0044]
Incidentally, in the above described embodiment, it is determined whether or not the prevention heating control can be executed based on the HC residual amount in step S 16 in Figure 6. The reason thereof is based on the fact that the main cause of deposit is the liquid particles 34 including HC. However, coexistence of the liquid particles 34 and the solid particles 32 is needed for generation of deposit as already described. When the residual amount of the solid particles 32 is large, the viscosity of the liquid particles 34 is likely to increase in a short time period. Based on the viewpoint like this, the determination is preferably performed not only based on the HC residual amount but also with the residual amount of the solid particles 32 taken into consideration. By also taking the residual amount of the solid particles 32 into consideration, it can be determined whether or not the prevention heating control can be executed more properly.
[0045]
Further, in the above described embodiment, it is determined whether or not the prevention heating control can be executed in step S16 in Figure 6, or it is determined whether or not the heating decomposition control can be executed in step S20 in Figure 6. However, these determinations can be also omitted. Namely, when the CPS 22 is determined as normal in step S 14 in Figure 6, the prevention heating control may be executed. Further, when the CPS 22 is determined as abnormal in step S14 in Figure 6, the heating decomposition control may be immediately executed.
[0046]
Further, in the above described embodiment, the difference between the heat generation amount parameter and the reference heat generation amount parameter is compared with the first threshold value and the second threshold value respectively in both step S14 and step S16 in Figure 6, but for them, different parameters may be respectively used. For example, in step S 14, abnormality determination of the CPS 22 is performed by different parameters, and in step S20, the difference between the heat generation amount parameter and the reference heat generation parameter may be used as described above.
[0047]
Further, in the above described embodiment, in step S20 in Figure 6, the amount of the deposit accumulating on the inner circumferential wall of the glow hole 28 is estimated based on the difference between the heat generation amount parameter and the reference heat generation amount parameter, but this may be estimated from an arithmetic operation and a map based on various engine parameters. Namely, during an operation of the diesel engine, the amount of the deposit accumulating on the inner circumferential wall of the glow hole 28 is calculated and integrated, and when the integrated value thereof exceeds a predetermined threshold value, the heating decomposition control may be executed. Note that the integrated value may be subjected to subtraction or the like by execution of the prevention heating control.
[0048]
Note that in the above described embodiment, the prevention heating control corresponds to "depositing prevention control" in the above described first aspect of the present invention, and the heating decomposition control corresponds to "deposit decomposition control" in the same aspect of the present invention, respectively.
Reference Signs List
[0049]
10 Diesel engine Cylinder
Piston
Cylinder head
Combustion chamber
Injector
Cylinder pressure sensor (CPS) Heater
Sensing section
glow hole
ECU
Solid particle
Liquid particle
Mixture gas
Deposit

Claims

Claims
[Claim 1]
A control device for an internal combustion engine including a glow plug-integrated type cylinder pressure sensor in which a pressure receiving section of the cylinder pressure sensor that detects pressure in a cylinder of the internal combustion engine is configured as a heater containing a heating element, the control device comprising:
means for performing start time control of controlling a temperature of the heater to be in a predetermined temperature range by performing energization to the heating element at a time of start of the internal combustion engine; and
means for, apart from the start time control, depositing prevention control of controlling a temperature around the heater to be in a first temperature range lower than the predetermined temperature range by performing energization to the heating element, deposit decomposition control of controlling the temperature range around the heater to be in a second temperature range that is higher than the first temperature by performing energization to the heating element are selectively performed.
[Claim 2]
The control device for an internal combustion engine according to claim 1 ,
wherein the first temperature range is a temperature range that is set in advance as a temperature range in which a liquid adhering to an inner circumferential wall of a glow hole between the heater and a cylinder head, and containing unbur ed fuel is vaporizable, and
the second temperature range is a temperature range that is set in advance as a temperature range in which deposit accumulating on the inner circumferential wall is decomposable.
[Claim 3]
The control device for an internal combustion engine according to claim 1 or 2, wherein a lower limit of the first temperature range is 180°C.
[Claim 4]
The control device for an internal combustion engine according to any one of claims 1 to
3,
wherein an upper limit of the first temperature range is 380°C.
[Claim 5] The control device for an internal combustion engine according to any one of claims 1 to
4,
wherein the depositing prevention control is executed conditionally upon an amount of unburned fuel that remains in the cylinder being equal to or larger than a predetermined amount. [Claim 6]
The control device for an internal combustion engine according to any one of claims 1 to
5,
wherein the deposit decomposition control is executed conditionally upon an amount of deposit that accumulates on an inner circumferential wall of a glow hole between the heater and a cylinder head being equal to or larger than a predetermined amount.
PCT/JP2015/057222 2014-03-18 2015-03-05 Control device for internal combustion engine WO2015141544A1 (en)

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JP5964877B2 (en) * 2014-03-25 2016-08-03 トヨタ自動車株式会社 In-cylinder pressure sensor control device

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EP3120013B1 (en) 2021-11-17
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JP6206272B2 (en) 2017-10-04
CN106103974B (en) 2020-01-14

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