Engine controller

Abstract

To provide an engine controller capable of reducing piston sound without sacrificing engine performance.SOLUTION: An engine controller 1 comprises: a shielding plate 40 that is provided so as to be extendable into a main combustion chamber 103, and, when extended, shields nozzle holes 106 formed in an area that does not include the center of gravity of a piston 101 as viewed from an axial direction of the piston 101, out of a plurality of nozzle holes 106 formed in a partition wall 105 separating the main combustion chamber 103 and an auxiliary combustion chamber 104; an electric motor 41 and a link mechanism 42 that drive the shielding plate 40; and an ECU 50 that controls the electric motor 41 and the link mechanism 42 to extend the shielding member when a piston sound level is equal to or larger than a predetermined threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine control device. [Background technology]

[0002] In an engine, the reciprocating linear motion of the piston is converted into rotational motion by the connecting rod (hereafter referred to as "connecting rod") and crankshaft. In such an engine, a force (side thrust) acts on the piston, pressing the side of the piston against the inner wall of the cylinder due to the tilt of the connecting rod (according to its swing). Here, the side on which the side thrust acts during the expansion stroke (immediately after top dead center of compression) is called the "thrust side," and the opposite side is called the "anti-thrust side."

[0003] However, the inclination of the connecting rod reverses at the top dead center of compression, reversing the direction of the side thrust (side pressure), causing the piston to wobble. This causes the side of the piston to collide with the inner wall of the cylinder (piston slap), resulting in a piston slapping noise.

[0004] Patent Document 1 discloses a control device for an internal combustion engine that can suppress the generation of piston slapping noise. More specifically, when the control device for an internal combustion engine determines that a piston-cylinder collision behavior is occurring, it maintains an engine output Pe corresponding to an engine required output Per while lowering the engine rotation speed Es below the engine rotation speed Est corresponding to the engine required output Per. That is, on the equal power output line, the engine output Pe is maintained by lowering the engine rotation speed Es below the engine rotation speed Est and increasing the engine load El.

[0005] Therefore, this internal combustion engine control device reduces the piston's inertial force and side pressure, and can stabilize the piston's oscillation in a direction that suppresses piston rotation. As a result, it is possible to suppress the generation of piston slapping noise caused by the piston-cylinder collision behavior. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-008010 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the control device for an internal combustion engine described in Patent Document 1 can suppress the occurrence of piston slap noise. However, in this internal combustion engine control device, in order to suppress piston slap noise, it is necessary to shift the engine operating state (engine rotation speed, engine load) from the optimum operating point of the engine (i.e., to reduce the engine rotation speed and increase the engine load). In other words, it is necessary to sacrifice engine performance in order to reduce (suppress) piston slap noise.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide an engine control device that can reduce piston slapping noise without sacrificing engine performance. [Means for solving the problem]

[0009] An engine control device according to one aspect of the present invention is a control device for an engine having a main combustion chamber and an auxiliary combustion chamber formed at the top of the main combustion chamber, and includes a blocking member that is arranged to be able to advance into the main combustion chamber or the auxiliary combustion chamber and, when advanced, blocks injection holes that are formed in an area that does not include the center of gravity of the piston as seen in the axial direction of the piston, out of multiple injection holes formed in a partition wall separating the main combustion chamber and the auxiliary combustion chamber; drive means for driving the blocking member; vibration detection means for detecting engine vibrations corresponding to piston tap sounds; and a control unit that controls the drive means based on the level of engine vibrations corresponding to piston tap sounds detected by the vibration detection means, and is characterized in that the control unit controls the drive means to advance the blocking member when the level of engine vibrations corresponding to piston tap sounds is equal to or greater than a predetermined threshold value.

[0010] According to an engine control device according to one aspect of the present invention, when the level of engine vibration corresponding to piston smacking noise exceeds a predetermined threshold, the driving means is controlled to advance the shielding member, thereby shielding the nozzle holes formed in a region of the partition wall separating the main combustion chamber and the auxiliary combustion chamber that does not include the center of gravity of the piston as viewed in the axial direction of the piston. Therefore, flame ejection from the auxiliary combustion chamber to a region of the main combustion chamber that does not include the center of gravity of the piston is suppressed relatively compared to flame ejection to a region that includes the center of gravity of the piston. Furthermore, combustion (flame propagation) in the region of the main combustion chamber that does not include the center of gravity of the piston is suppressed relatively compared to combustion (flame propagation) in the region that includes the center of gravity of the piston, thereby reducing the combustion pressure acting on the region of the piston crown surface that does not include the center of gravity of the piston. In other words, the combustion pressure acting on the region of the piston crown surface that includes the center of gravity of the piston is relatively increased. Therefore, the moment around the piston pin can be reduced to zero (or approximately zero). This reduces the inclination of the piston to zero (or approximately zero). As a result, it is possible to reduce piston slap noise without changing the engine operating state (without shifting it from the optimum operating point), i.e., without sacrificing engine performance. [Effects of the Invention]

[0011] According to the present invention, it is possible to reduce piston slap noise without sacrificing engine performance. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing the configuration of an engine control device according to an embodiment and an engine with a sub-chamber to which the engine control device is applied; [Figure 2] FIG. 10 is a diagram showing an example of a drive amount (rotation angle) map (or an advance amount map). [Figure 3] 5 is a diagram for explaining a method for learning the minimum value of the link mechanism rotation angle (or the shielding plate advancement amount) by the engine control device according to the embodiment. FIG. [Figure 4] 5 is a flowchart showing a processing procedure for piston slapping noise reduction control (part 1: piston slapping noise countermeasure area learning processing) performed by the engine control device according to the embodiment. [Figure 5] 5 is a flowchart showing a processing procedure for piston slap noise reduction control (part 2: piston slap noise minimization link mechanism rotation angle (or shield plate advancement amount) learning processing) by the engine control device according to the embodiment. [Figure 6] 1 is a diagram for explaining the action and effect of the engine control device according to the embodiment (a diagram showing the piston behavior immediately after the top dead center of compression). FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be designated by the same reference numerals. In addition, the same elements will be designated by the same reference numerals in each drawing, and redundant explanations will be omitted.

[0014] First, the configuration of an engine control device 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the configuration of the engine control device 1 and an engine with a sub-chamber (hereinafter also simply referred to as "engine") 10 to which the engine control device 1 is applied.

[0015] The engine 10 is, for example, a horizontally opposed four-cylinder gasoline engine. The engine 10 is also a pre-chamber engine that includes a main combustion chamber 103 and a pre-chamber (pre-chamber) 104 formed at the top of the main combustion chamber 103. A partition wall 105, for example, dome-shaped (hemispherical), that separates the main combustion chamber 103 from the pre-chamber 104 has a plurality of injection holes (pre-chamber injection holes) 106 formed therein. Details will be described later.

[0016] In engine 10, the reciprocating linear motion of piston 101 is converted into rotational motion by connecting rod 102 and a crankshaft (not shown). The center of gravity of piston 101 is offset toward the thrust side, for example, in consideration of friction, etc. Since the center of gravity is offset toward the thrust side, when piston 101 moves (transfers) from top dead center toward bottom dead center, an inertial force acts upward (toward top dead center) with the center of gravity as the point of action, generating a moment in a direction that causes piston 101 to oscillate (see FIG. 6).

[0017] In the engine 10, air taken in through an air cleaner 16 is throttled by a throttle valve 13 provided in an intake pipe 15, passes through an intake manifold 11, and is taken into each cylinder formed in the engine 10. The opening of the throttle valve 13 is detected by a throttle opening sensor 35. The amount of air taken in through the air cleaner 16 is detected by an air flow meter 14 disposed between the air cleaner 16 and the throttle valve 13.

[0018] An injector 12 that injects fuel is attached to the pre-combustion chamber 104 of each cylinder of the engine 10. The injector 12 injects pressurized fuel into the pre-combustion chamber of each cylinder. That is, in this embodiment, an active pre-chamber is used that introduces (injects) fuel into the pre-combustion chamber (pre-chamber) 104. Note that a passive pre-chamber may also be used in which the injector 12 is attached to the main combustion chamber 103 and introduces the air-fuel mixture formed in the main combustion chamber 103 into the pre-combustion chamber (pre-chamber) 104.

[0019] In addition, a spark plug 17 that ignites the air-fuel mixture is attached to the auxiliary combustion chamber 104. In the auxiliary combustion chamber 104 of each cylinder of the engine 10, the mixture of intake air and fuel injected by the injector 12 is ignited by the spark plug 17 to generate a flame. The generated flame, together with unburned gas, is then ejected into the main combustion chamber 103 through multiple injection holes 106 and combusts in the main combustion chamber.

[0020] The exhaust gas after combustion is discharged through an exhaust pipe (exhaust manifold, exhaust pipe) 18. An air-fuel ratio sensor 37 is attached downstream of the assembly part of the exhaust pipe 18 and upstream of the exhaust purification catalyst 25. As the air-fuel ratio sensor 37, a linear air-fuel ratio sensor (LAF sensor) is used which can output a signal corresponding to the oxygen concentration and unburned gas concentration in the exhaust gas (i.e., a signal corresponding to the air-fuel ratio of the mixture) and can linearly detect the air-fuel ratio.

[0021] An exhaust purification catalyst 25 is disposed downstream of the air-fuel ratio sensor 37. The exhaust purification catalyst 25 is a three-way catalyst that simultaneously oxidizes hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas and reduces nitrogen oxides (NOx), thereby purifying harmful gas components in the exhaust gas into harmless carbon dioxide (CO2), water vapor (H2O), and nitrogen (N2).

[0022] The injectors 12 are connected to a delivery pipe (common rail) 24. The delivery pipe 24 distributes fuel pumped from a high-pressure fuel pump 22 through a fuel pipe 23 to the injectors 12. The high-pressure fuel pump 22 pressurizes the fuel drawn up from a fuel tank 20 by a feed pump (low-pressure fuel pump) 21 to a high pressure (for example, 8 to 13 MPa) depending on the operating state, and supplies the fuel to the delivery pipe 24. In this embodiment, a type of high-pressure fuel pump 22 driven by a camshaft 19 of the engine 10 is used as the high-pressure fuel pump 22.

[0023] Each cylinder of the engine 10 described above is provided with a plate-shaped shielding plate 40 (corresponding to a shielding member in the claims) that can advance (protrude) into the main combustion chamber 103 (or the auxiliary combustion chamber 104). When the shielding plate 40 advances, it covers and shields the nozzle holes 106 that are formed in an area that does not include the center of gravity of the piston 101 as viewed in the axial direction of the piston 101, out of multiple nozzle holes (auxiliary chamber nozzle holes) 106 formed in a partition wall 105 that separates the main combustion chamber 103 and the auxiliary combustion chamber 104. That is, the shielding plate 40 changes the shielding area of ​​the nozzle holes 106 that spray flames generated in the auxiliary combustion chamber 104 into the main combustion chamber 103, depending on the amount of advancement. The shielding plate 40 is made of a metal such as cast iron, and is formed to withstand the combustion temperature and combustion pressure.

[0024] The shielding plate 40 is driven by, for example, an electric motor 41 and a link mechanism 42 that converts the rotational motion of the electric motor 41 into linear motion of the shielding member (linear motion in the cylinder radial direction). That is, the shielding plate 40 is pushed out or pulled back (returned to its original position) in the radial direction of the cylinder by the electric motor 41 and the link mechanism 42. Therefore, the electric motor 41 and the link mechanism 42 function as a driving means as recited in the claims. A sensor such as a rotary encoder 43 is attached to the link mechanism 42 to detect the rotation angle of the link mechanism 42 (an index value correlated with the amount of advancement of the shielding plate 40). In addition, the shielding plate 40 and the link mechanism 42 are sealed to prevent combustion gas leakage.

[0025] Incidentally, instead of the electric motor 41 and link mechanism 42 described above, the configuration for driving the shielding plate 40 can be, for example, a rack-and-pinion mechanism that combines a gear (pinion gear) attached to the tip of the electric motor and rotated by the drive of the electric motor with a rack with linearly attached teeth. Also, for example, a system can be employed in which a ball screw is rotated by a feed motor and converted into linear motion. Furthermore, the shielding plate 40 can also be configured to be directly and linearly driven by a linear motor, linear solenoid, or the like.

[0026] In addition to the air flow meter 14, air-fuel ratio sensor 37, throttle opening sensor 35, and rotary encoder 43 described above, a cam angle sensor 38 for identifying the cylinders of the engine 10 is attached near the camshaft of the engine 10. Also, a crank angle sensor 33 for detecting the rotational position of the crankshaft is attached near the crankshaft of the engine 10. The cam angle sensor 38 and the crank angle sensor 33 may be, for example, electromagnetic pickup types.

[0027] Additionally, a knock sensor 39 is attached to the cylinder block of the engine 10 to detect vibrations caused by knocking (abnormal combustion) of the engine 10. When the engine 10 (cylinder block) vibrates, a weight built into the knock sensor 39 vibrates, and a force is applied to a piezoelectric element (piezoelectric ceramics), generating an electric signal. This is the principle by which the knock sensor 39 detects engine vibrations.

[0028] In this embodiment, the knock sensor 39 is used to detect engine vibrations (i.e., engine vibrations corresponding to piston slap noises) caused by the side surface of the piston colliding with the inner wall of the cylinder (occurrence of piston slap). Therefore, the knock sensor 39 functions as vibration detection means recited in the claims.

[0029] These sensors are connected to an engine control unit (hereinafter referred to as "ECU") 50. Also connected to the ECU 50 are various sensors, such as a water temperature sensor 32 that detects the temperature of the coolant for the engine 10, an oil temperature sensor 31 that detects the temperature of the lubricating oil, an accelerator pedal operation amount sensor 34 that detects the amount of depression of the accelerator pedal, and a vehicle speed sensor 36 that detects the speed of the vehicle.

[0030] The ECU 50 includes a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute various processes, a RAM that stores various data such as calculation results, a backup RAM that maintains the stored contents using a battery or the like, and an input / output I / F, etc. The ECU 50 also includes an injector driver that drives the injector 12, a drive circuit that drives an electromagnetic valve (solenoid valve) that constitutes the high-pressure fuel pump, an output circuit that outputs an ignition signal, etc. The ECU 50 also includes a motor driver that drives the electric motor 41, etc.

[0031] The ECU 50 identifies the cylinder from the output of the cam angle sensor 38, and determines the rotational angular velocity and engine speed from the output of the crank angle sensor 33. The ECU 50 also determines the engine load (g / rev) based on the intake air amount detected by, for example, the air flow meter 14. The ECU 50 also acquires various information such as the intake air amount, the air-fuel ratio of the mixture, the accelerator pedal operation amount, engine vibration (piston slapping sound), and the water temperature and oil temperature of the engine 10 based on detection signals input from the various sensors described above.

[0032] Based on the acquired information, the ECU 50 comprehensively controls the engine 10 by controlling various devices such as the fuel injection amount (fuel injection time), ignition timing, throttle valve 13, and electric motor 41. The ECU 50 functions as a control unit as defined in the claims.

[0033] In particular, the ECU 50 has a function to reduce piston slap noise without sacrificing engine performance. The ECU 50 realizes this function by having a microprocessor execute a program stored in an EEPROM or the like.

[0034] Therefore, the ECU 50 controls the electric motor 41 and the link mechanism 42 (i.e., adjusts the amount of advancement of the shielding plate 40 (the shielding area of ​​the nozzle hole 106)) based on the degree of engine vibration corresponding to the piston knock (piston knock level). More specifically, when the piston knock level is equal to or greater than a predetermined threshold, the ECU 50 controls the electric motor 41 and the link mechanism 42 to advance (protrude) the shielding plate 40 into the main combustion chamber 103 (i.e., to shield the nozzle hole 106 formed in an area not including the center of gravity of the piston 101).

[0035] Here, the ECU 50 performs, for example, band-pass filtering to selectively pass engine vibrations of a piston slap frequency and averaging processing on the engine vibrations detected by the knock sensor 39, and obtains the peak-to-peak value of the output value as the piston slap level. Note that the band-pass filter may be configured by hardware.

[0036] As described above, when the piston slapping sound level is equal to or higher than a predetermined threshold, the ECU 50 controls the electric motor 41 and the link mechanism 42 to advance the shielding plate 40, thereby shielding the nozzle holes 106 formed in the partition wall 105 separating the main combustion chamber 103 and the auxiliary combustion chamber 104, the nozzle holes 106 formed in an area (anti-thrust side) that does not include the center of gravity of the piston 101 when viewed from the axial direction of the piston 101. Therefore, the ejection of flame from the auxiliary combustion chamber 104 into an area of ​​the main combustion chamber 103 that does not include the center of gravity of the piston 101 is suppressed relatively to the ejection of flame into an area that includes the center of gravity of the piston 101.

[0037] Then, combustion (flame propagation) in a region of the main combustion chamber 103 that does not include the center of gravity of the piston 101 is relatively suppressed compared to combustion (flame propagation) in a region that includes the center of gravity of the piston 101, and the combustion pressure acting on the region of the piston crown surface that does not include the center of gravity of the piston 101 (anti-thrust side) becomes relatively low. In other words, the combustion pressure acting on the region of the piston crown surface that includes the center of gravity of the piston 101 (thrust side) becomes relatively high. As a result, the moment around the piston pin becomes zero (or approximately zero), and oscillation (tilting) of the piston 101 is suppressed.

[0038] More specifically, first, the ECU 50 learns an engine operating state (piston slap countermeasure region) in which the piston slap sound level is equal to or greater than a predetermined threshold value (i.e., the piston slap sound becomes relatively loud). At this time, the engine operating state (piston slap sound countermeasure region) is determined by, for example, the engine speed and the engine load.

[0039] Next, the ECU 50 learns the advancement amount of the shielding plate 40 or the rotation angle of the link mechanism 42 (corresponding to the drive amount of the drive means described in the claims) at which the piston slap noise level takes a minimum value in the learned engine operating state (piston slap noise countermeasure region), as shown in FIG. 3 . Here, the advancement amount of the shielding plate 40 may be measured directly or indirectly from the rotation angle of the link mechanism 42, etc. Furthermore, the rotation angle of the link mechanism 42 may be measured directly or may be estimated from the drive amount (rotation angle) of the electric motor 41 that drives the link mechanism 42, the applied current, the applied voltage (an index value correlated with the advancement amount of the shielding plate 40), etc. As described above, in this embodiment, a configuration is adopted in which the rotation angle of the link mechanism 42 is directly measured. Therefore, the following description will mainly focus on this configuration.

[0040] 3 is a diagram for explaining a method for learning (a method for searching for) the minimum value of the rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40) by the engine control device 1. In FIG. 3, the horizontal axis represents the rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40), and the vertical axis represents the piston slapping sound level. Note that a known method (algorithm) can be used as a method for searching for the rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40) at which the piston slapping sound level takes the minimum value.

[0041] At that time, the ECU 50 generates a drive amount (rotation angle) map (lookup table) that defines the relationship between the learned multiple engine operating states and the rotation angles of the multiple link mechanisms 42 learned for each of the multiple engine operating states (regions) (or an advance amount map that defines the relationship between the learned multiple engine operating states (engine speed, engine load) and the advance amounts of the multiple shielding plates 40 learned for each of the multiple engine operating states (regions)).

[0042] Then, after learning the rotation angle of the link mechanism 42 (or the amount of advancement of the shielding plate 40) (after generating the drive amount map (or advance amount map)), if the engine is in an operating state (piston hammering noise countermeasure area) where the piston hammering noise level is above a predetermined threshold, the ECU 50 uses the drive amount map (or advance amount map) to control the electric motor 41 and the link mechanism 42 (i.e., adjusts the amount of advancement of the shielding plate 40 (= shielding area of ​​the nozzle hole 106)).

[0043] That is, the ECU 50 stores in an EEPROM or the like a drive amount (rotation angle) map (or advancement amount map) that defines the relationship between the engine speed, engine load, and the rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40), and determines the target rotation angle of the link mechanism 42 (or the target advancement amount of the shielding plate 40) by searching this drive amount map (or advancement amount map) based on the detected engine speed and engine load.Then, the ECU 50 controls the electric motor 41 in real time based on the target rotation angle of the link mechanism 42 (or the target advancement amount of the shielding plate 40).

[0044] An example of the drive amount (rotation angle) map (or advance amount map) is shown in FIG. 2. In FIG. 2, the horizontal axis represents engine speed (rpm), and the vertical axis represents engine load (g / rev). In the drive amount map (or advance amount map), the learned rotation angle of the link mechanism 42 (or the advance amount of the shielding plate 40) is stored for each combination (lattice point) of engine speed and engine load (i.e., for each learned engine operating region (piston slapping noise countermeasure region)). In the drive amount map (or advance amount map), the rotation angle of the link mechanism 42 (or the advance amount of the shielding plate 40) is learned and set, for example, in the low rotation / low load region and the high rotation / medium to high load region (engine operating region (piston slapping noise countermeasure region) in which the piston slapping noise level is equal to or greater than a predetermined threshold value) shown by the hatched area in FIG. 2.

[0045] In addition, when the engine is in an operating state (piston knock noise countermeasure region) where the piston knock noise level is equal to or higher than a predetermined threshold (i.e., when the shielding plate 40 is advanced), it is preferable that the ECU 50 prohibits (stops) the operation of a device that generates turbulence (tumble, swirl, etc.) in the combustion chamber of the engine 10 in order to prevent the non-uniform flame propagation from being disrupted, i.e., to prevent the flame propagation from being uniform.

[0046] That is, when the engine is in an operating state where the piston slap noise level is equal to or greater than a predetermined threshold (a piston slap noise countermeasure region), the ECU 50 prohibits the driving (opening / closing) of a tumble generator valve (not shown) that adjusts the strength of tumble in the cylinder. Here, the tumble generator valve is a device that opens and closes in response to, for example, the accelerator operation amount, etc., to vary the tumble ratio (tumble vortex). Note that, when the engine is in an operating state where the piston slap noise level is less than the predetermined threshold (an operating region where piston slap noise is relatively small), turbulence may be generated (i.e., the tumble generator valve may be driven).

[0047] Next, the operation of the engine control device 1 will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a flowchart showing the procedure for piston slap noise reduction control (part 1: learning process for piston slap noise countermeasure area) by the engine control device 1. Fig. 5 is a flowchart showing the procedure for piston slap noise reduction control (part 2: learning process for piston slap noise minimization link mechanism rotation angle (or shield plate advance amount)). This process is repeatedly executed at a predetermined timing by the ECU 50.

[0048] First, the learning process for the piston slap noise countermeasure area will be described with reference to Fig. 4. In step S100, it is determined whether or not learning has been completed for all engine operating regions (map grids) as to whether or not they are piston slap noise countermeasure areas. If learning has been completed for all engine operating regions (map grids) as to whether or not they are piston slap noise countermeasure areas, the process proceeds to step S200 (learning process for the piston slap noise minimizing link mechanism rotation angle (or shield plate advance amount)). On the other hand, if there is an engine operating region (map grid) for which learning has not been completed as to whether or not it is a piston slap noise countermeasure area, the process proceeds to step S102.

[0049] In step S102, it is determined whether the current engine operating range (engine speed, engine load) has been learned as to whether it is a piston slapping noise countermeasure range (i.e., whether the current engine operating range is a learned engine operating range (map grid)). If the current engine operating range is a learned engine operating range, the process proceeds to step S200. On the other hand, if the current engine operating range has not been learned, the process proceeds to step S104.

[0050] In step S104, the engine vibration detected by the knock sensor 39 is read. In the following step S106, in order to extract the piston slap sound (to remove noise other than the piston slap sound), the read engine vibration is passed through a band-pass filter that selectively passes engine vibration of the piston slap sound frequency (filter processing is performed).

[0051] Subsequently, in step S108, an averaging process is performed on a predetermined number (predetermined number of cycles) of extracted piston slap sounds, and the peak-to-peak value of the piston slap sounds (average value) is acquired (defined) as the piston slap sound level.

[0052] Next, in step S110, it is determined whether the piston slap sound level is equal to or greater than a predetermined threshold value. If the piston slap sound level is equal to or greater than the predetermined threshold value, the process proceeds to step S112. On the other hand, if the piston slap sound level is less than the predetermined threshold value, the process proceeds to step S114.

[0053] In step S112, it is learned that the current engine operating state (engine speed, engine load) is an engine operating state in which the piston slap noise level is relatively large and countermeasures against piston slap noise are required (piston slap noise countermeasure area). After that, the process proceeds to step S200 of the piston slap noise minimization link mechanism rotation angle (or shield plate advancement amount) learning process.

[0054] On the other hand, in step S114, it is learned that the current engine operating state (engine speed, engine load) is an engine operating state (region) in which the piston slap noise level is relatively small and no countermeasures against piston slap noise are required. After that, the process proceeds to step S200 of the piston slap noise minimization link mechanism rotation angle (or shield plate advancement amount) learning process.

[0055] Next, the learning process of the link mechanism rotation angle (or shield plate advancement amount) for minimizing piston slap noise will be described with reference to Fig. 5. In step S200, it is determined whether the link mechanism rotation angle (or shield plate advancement amount) for minimizing piston slap noise has been learned for all piston slap noise countermeasure areas (map grids). If the link mechanism rotation angle (or shield plate advancement amount) for minimizing piston slap noise has been learned for all piston slap noise countermeasure areas (map grids), the process proceeds to step S300. On the other hand, if there is a piston slap noise countermeasure area (map grid) for which the link mechanism rotation angle (or shield plate advancement amount) for minimizing piston slap noise has not been learned, the process proceeds to step S202.

[0056] In step S202, it is determined whether the current engine operating state (engine speed, engine load) is in an engine operating state (piston slapping noise countermeasure region) where piston slapping noise countermeasures are required. If the engine operating state (region) is in a state where piston slapping noise countermeasures are not required, the shielding plate 40 is retracted in step S302, and the process temporarily exits. On the other hand, if the engine operating state is in a state where piston slapping noise countermeasures are required (piston slapping noise countermeasure region), the process proceeds to step S204.

[0057] In step S204, it is determined whether or not the link mechanism rotation angle (or the shielding plate advancement amount) that minimizes piston slapping noise has been learned for the current engine operating state (engine speed, engine load) (i.e., whether or not the current engine operating state (area) is in the learned piston slapping noise countermeasure area). If the current engine operating state (area) is in the learned piston slapping noise countermeasure area, the shielding plate 40 is retracted in step S302, and then the process temporarily exits. On the other hand, if the current engine operating state (area) has not been learned, the process proceeds to step S206.

[0058] In step S206, the electric motor 41 and the link mechanism 42 are controlled (driven) to advance the shielding plate 40. That is, of the multiple nozzle holes 106 formed in the partition wall 105 separating the main combustion chamber 103 and the auxiliary combustion chamber 104, the nozzle holes 106 formed in an area (anti-thrust side) that does not include the center of gravity of the piston 101 as viewed in the axial direction of the piston 101 are covered and shielded.

[0059] In the following step S208, the engine vibration detected by the knock sensor 39 is read in. In the following step S210, in order to extract the piston slap sound (to remove noise other than the piston slap sound), the read engine vibration is passed through a band-pass filter that selectively passes engine vibration of the piston slap sound frequency (filter processing is performed).

[0060] Subsequently, in step S212, an averaging process is performed on a predetermined number (predetermined number of cycles) of extracted piston slap sounds, and the peak-to-peak value of the piston slap sounds (average value) is acquired (defined) as the piston slap sound level.

[0061] Next, in step S214, it is determined whether the piston slap sound level has reached a minimum value (i.e., whether the link mechanism rotation angle (or the shield plate advancement amount) is at a value at which the piston slap sound level reaches a minimum value). If the piston slap sound level has reached a minimum value, the process proceeds to step S216. On the other hand, if the piston slap sound level has not reached a minimum value, the rotation angle of the link mechanism 42 (the advancement amount of the shield plate 40) is changed, and the processes of steps S206 to S214 described above are executed again.

[0062] In step S216, the current link mechanism rotation angle (or shield plate advancement amount) is learned as the link mechanism rotation angle (or shield plate advancement amount) at which the piston slapping noise level takes the minimum value in the current piston slapping noise countermeasure area (map grid).

[0063] Next, in step S218, it is determined whether or not the link mechanism rotation angle (or the shield plate advancement amount) that minimizes piston slap noise has been learned for all piston slap noise countermeasure areas (map grids). If the link mechanism rotation angle (or the shield plate advancement amount) that minimizes piston slap noise has been learned for all piston slap noise countermeasure areas (map grids), the process proceeds to step S300. On the other hand, if there is a piston slap noise countermeasure area (map grid) for which the link mechanism rotation angle (or the shield plate advancement amount) that minimizes piston slap noise has not been learned, the process temporarily exits after the shield plate 40 is retracted in step S302.

[0064] In step S300, the electric motor 41 and the link mechanism 42 are controlled (the advancement amount of the shielding plate 40 is adjusted) using the learned drive amount map (or advancement amount map). After that, the process temporarily exits from this process.

[0065] As explained above in detail, according to this embodiment, when the piston slapping sound level reaches or exceeds a predetermined threshold, the electric motor 41 and the link mechanism 42 are controlled to advance the shielding plate 40, and the nozzle holes 106 formed in the partition wall 105 separating the main combustion chamber 103 and the auxiliary combustion chamber 104, which are formed in an area not including the center of gravity of the piston 101 as viewed in the axial direction of the piston 101, are shielded. Therefore, the ejection of flame from the auxiliary combustion chamber 104 into an area of ​​the main combustion chamber 103 not including the center of gravity of the piston is suppressed relatively to the ejection of flame into an area including the center of gravity of the piston.

[0066] As a result, combustion (flame propagation) in the region of the main combustion chamber 103 that does not include the center of gravity of the piston is relatively suppressed compared to combustion (flame propagation) in the region that includes the center of gravity of the piston, and the combustion pressure acting on the region of the piston crown surface that does not include the center of gravity of the piston (anti-thrust side) becomes relatively low. In other words, the combustion pressure acting on the region of the piston crown surface that includes the center of gravity of the piston (thrust side) becomes relatively high. As a result, the moment around the piston pin can be made zero (or approximately zero). In other words, the tilt of the piston 101 can be made zero (or approximately zero). Meanwhile, the total amount of energy remains approximately unchanged. As a result, it is possible to reduce piston slap noise without changing the operating state of the engine 10 (without shifting it from the optimal operating point), i.e., without sacrificing engine performance.

[0067] 6 is a diagram for explaining the operation and effect of the engine control device 1 according to the embodiment (a diagram showing the piston behavior immediately after the compression top dead center). In FIG. 6, the dashed line indicates the piston behavior when the shielding plate 40 is not advanced (when the injection hole 106 is not shielded).

[0068] Furthermore, according to this embodiment, piston slapping noise can be reduced by control, so it is possible to design the piston shape, etc., by prioritizing other performance such as friction (i.e., without prioritizing the reduction of piston slapping noise).

[0069] In particular, according to this embodiment, an engine operating state (piston slap noise countermeasure region) in which the piston slap noise level is equal to or greater than a predetermined threshold is learned, and the rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40) in which the piston slap noise level is minimized in the learned engine operating state (piston slap noise countermeasure region) is learned. After the rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40) is learned, when the engine is in the learned engine operating state (piston slap noise countermeasure region), the electric motor 41 and the link mechanism 42 are controlled based on the learned rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40), and the advancement amount of the shielding plate 40, i.e., the shielding area of ​​the injection hole 106, is adjusted. This eliminates the need for engine calibration, which involves tuning control constants related to piston slap noise reduction in advance, thereby reducing the calibration process. Furthermore, individual variations in the engine 10 can be eliminated (absorbed).

[0070] Furthermore, according to this embodiment, a drive amount (rotation angle) map (or advancement amount map) is generated that defines the relationship between a plurality of learned engine operating states (piston slap noise countermeasure regions) and a plurality of link mechanism rotation angles (or shield plate advancement amounts) learned for each of the plurality of engine operating states. When the engine is in a learned engine operating state (piston slap noise countermeasure region), the electric motor 41 and the link mechanism 42 are controlled using the learned drive amount (rotation angle) map (or advancement amount map), and the advancement amount of the shield plate 40, i.e., the shielding area of ​​the injection hole 106, is adjusted. Therefore, (by creating a map), it is possible to easily control an object having nonlinear characteristics (which are difficult to express mathematically). Furthermore, the processing speed of the ECU 50 can be improved.

[0071] According to this embodiment, the engine operating state (operating conditions) is determined by the engine speed and the engine load, so that the operating state that causes the piston slapping noise to become loud can be properly determined.

[0072] According to this embodiment, when the engine is in the learned operating state (piston slapping noise countermeasure region), the device that generates turbulence in the combustion chamber of the engine 10 is prohibited (stopped) from being driven, thereby preventing the non-uniform flame propagation from being disrupted (uniformized).

[0073] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiments, the present invention has been described as being applied to a horizontally opposed engine, but the present invention can also be applied to, for example, an in-line or V-type engine. Furthermore, the present invention can be applied to a diesel engine instead of a gasoline engine. Furthermore, the present invention is not limited to conventional engine vehicles, but can also be applied to, for example, a hybrid vehicle (HEV) equipped with an engine and an electric motor as a driving power source.

[0074] The material, shape, etc. of the shielding plate 40 can be changed as desired depending on requirements such as heat resistance and pressure resistance. Furthermore, as a configuration for driving the shielding plate 40, instead of the electric motor 41 and link mechanism 42 described above, for example, a rack and pinion, a ball screw, etc., or a linear motor, a linear solenoid, etc. can also be used. In that case, in order to grasp the advancement amount of the shielding plate 40 (the shielding area of ​​the injection hole 106), instead of the rotation angle of the link mechanism 42, a parameter (an index value correlated with the advancement amount of the shielding plate 40) suitable for the configuration to be adopted, such as the rotation angle of the motor, applied current, applied voltage, etc., can be used.

[0075] Furthermore, the method of searching for the minimum point (value) of the rotation angle of the link mechanism 42 (or the advancement amount of the shielding plate 40) is not limited to the above embodiment, and any suitable method (algorithm) can be adopted. [Explanation of symbols]

[0076] 1 Engine control device 10 Engine 101 Piston 102 Connecting rod 103 Main combustion chamber 104 Auxiliary combustion chamber 105 Bulkhead 106 Nozzle hole (auxiliary chamber nozzle hole) 11 Intake manifold 12 injectors 13 Throttle valve 14 Air flow meter 15 Intake pipe 16 Air cleaner 17 Spark plug 18 Exhaust pipe (exhaust manifold, exhaust pipe) 19 Camshaft 20 Fuel Tank 21 Feed pump 22 High-pressure fuel pump 23 Fuel piping 24 Delivery Pipe 25 Exhaust purification catalyst 31 Oil temperature sensor 32 Water temperature sensor 33 Crank angle sensor 34 Accelerator pedal operation amount sensor 35 Throttle opening sensor 36 Vehicle speed sensor 37 Air-fuel ratio sensor (LAF sensor) 38 Cam angle sensor 39 Knock sensor 40 Shield plate 41 Electric motor 42 Link mechanism 43 Rotary encoder (rotation angle sensor) 50 ECU

Claims

1. A control device for an engine having a main combustion chamber and a sub-combustion chamber formed at the top of the main combustion chamber, a shielding member that is provided so as to be able to advance into the main combustion chamber or the auxiliary combustion chamber, and that, when advanced into the main combustion chamber, shields the nozzle holes that are formed in an area that does not include the center of gravity of the piston as viewed in the axial direction of the piston, among a plurality of nozzle holes formed in a partition wall that separates the main combustion chamber and the auxiliary combustion chamber; a driving means for driving the shielding member; a vibration detection means for detecting engine vibrations corresponding to piston smacking sounds; a control unit that controls the driving means based on the degree of engine vibration corresponding to the piston slapping sound detected by the vibration detection means, The engine control device is characterized in that the control unit controls the driving means to advance the shielding member when the degree of engine vibration corresponding to piston slapping noise is equal to or greater than a predetermined threshold value.

2. The control unit The engine operating state in which the degree of engine vibration corresponding to piston slapping noise is equal to or greater than a predetermined threshold value is learned, and learning the advancement amount of the shielding member or the drive amount of the drive means at which the degree of engine vibration corresponding to piston slapping noise takes a minimum value in the learned engine operating state; After learning the advancement amount of the shielding member or the drive amount of the drive means, when the engine is in the learned operating state, the drive means is controlled based on the learned advancement amount of the shielding member or the drive amount of the drive means.

2. The engine control device according to claim 1.

3. The control unit generating an advancement amount map that defines a relationship between the learned plurality of engine operating states and the advancement amounts of the shielding member learned for each of the plurality of engine operating states, or a drive amount map that defines a relationship between the learned plurality of engine operating states and the drive amounts of the drive means learned for each of the plurality of engine operating states; When the engine is in the learned operating state, the driving means is controlled using the advance amount map or the drive amount map.

3. The engine control device according to claim 2.

4. 4. The engine control device according to claim 3, wherein the engine operating state is determined by an engine speed and an engine load.

5. 5. The engine control device according to claim 4, wherein the control unit prohibits the driving of a device that generates turbulence in a combustion chamber of the engine when the engine is in the learned operating state.

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