Engine control device

Abstract

To provide an engine control device which can reduce piston striking sound without sacrificing the engine performance.SOLUTION: An engine control device 1 includes: a weight 61 having a predefined mass; a belt conveyor 60 which is attached on a back face of the piston 101, and which moves the weight 61 in a direction orthogonal to an axis of a piston pin 1011 between an area containing the piston gravity and an area not containing the piston gravity across the axis of the piston pin 1011 as boundary when viewed from an axial direction of the piston 101; and an ECU 50 for controlling the belt conveyor 60 (an electric motor 603) such that the weight 61 is moved to the area not containing the piston gravity when a level of engine vibration corresponding to a piston striking sound is equal to or higher than a predefined threshold value.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 compression top dead center, and the direction of the side thrust (side pressure) reverses, causing the inclination of the piston to change, resulting in the so-called piston wobble. This causes the side of the piston to collide with the inner wall of the cylinder (piston slap), resulting in 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 includes vibration detection means for detecting engine vibrations corresponding to piston thumps; a weight having a predetermined mass and movably attached to a back surface of the piston; moving means for moving the weight between an area including the piston center of gravity and an area not including the piston center of gravity, with the axis of the piston pin as the boundary, as viewed in the axial direction of the piston; and a control unit for controlling the moving means based on the level of engine vibrations corresponding to the piston thumps detected by the vibration detection means, wherein the control unit controls the moving means to move the weight to the area not including the piston center of gravity when the level of engine vibrations corresponding to the piston thumps is equal to or greater than a predetermined threshold.

[0010] According to an engine control device according to one aspect of the present invention, when the level of engine vibrations corresponding to piston slap noise exceeds a predetermined threshold, a weight having a predetermined mass is moved to an area of ​​the piston axial direction, with the piston pin axis as the boundary, that does not include the center of gravity of the piston. Therefore, by moving the weight so as to cancel out the offset of the piston center of gravity, the center of gravity of the piston can be brought (shifted) to coincide with the axis of the piston pin. This makes it possible to zero (or nearly zero) the moment around the piston pin. In other words, it makes it possible to zero (or nearly zero) the tilt of the piston. As a result, it becomes possible to reduce piston slap noise without changing the operating state of the engine (without shifting it from the optimal 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 a direct injection engine to which the engine control device is applied; [Figure 2]2 is a view of a belt conveyor constituting the engine control device according to the embodiment, seen from the rear (back) side of the piston. FIG. [Figure 3] FIG. 4 is a diagram showing an example of a motor rotation angle map. [Figure 4] 5 is a diagram for explaining a method for learning the minimum value of the motor rotation angle by the engine control device according to the embodiment. FIG. [Figure 5] 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 6] 5 is a flowchart showing a processing procedure for piston slap noise reduction control (part 2: piston slap noise minimization motor rotation angle learning processing) performed by the engine control device according to the embodiment. [Figure 7] 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 Figures 1 and 2. Figure 1 is a diagram showing the configuration of the engine control device 1 and a direct injection engine (hereinafter also simply referred to as "engine") 10 to which the engine control device 1 is applied. Figure 2 is a diagram showing a belt conveyor 60 constituting the engine control device 1 as seen from the rear (backside) of a piston 101.

[0015] The engine 10 may be of any type, but is, for example, an in-line four-cylinder gasoline engine. The engine 10 is a direct injection engine that directly injects fuel into the cylinders 103 (intra-cylinder). In the engine 10, the reciprocating linear motion of the piston 101 is converted into rotational motion by the connecting rod 102 and the crankshaft. The center of gravity of the piston 101 is offset to the thrust side, for example, in consideration of friction, etc. Since the center of gravity is offset to the thrust side, when the piston 101 moves (transfers) from top dead center to bottom dead center, an inertial force acts upward (toward top dead center) with the center of gravity as the point of application, generating a moment in a direction that oscillates the piston 101 (see FIG. 7).

[0016] 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.

[0017] Each cylinder of engine 10 is fitted with an injector 12 that injects fuel into cylinder 103. The injector 12 injects pressurized fuel directly into the combustion chamber of each cylinder. A spark plug 17 that ignites the air-fuel mixture is attached to the top of the combustion chamber. In each cylinder of engine 10, the mixture of intake air and fuel injected by injector 12 is ignited by spark plug 17 and burns. Exhaust gas after combustion is discharged through an exhaust pipe (exhaust manifold, exhaust pipe) 18.

[0018] An air-fuel ratio sensor 37 is attached downstream of the collecting portion 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.

[0019] 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).

[0020] 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 each injector 12. The high-pressure fuel pump 22 pressurizes 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.

[0021] A belt conveyor 60 (corresponding to the moving means described in the claims) is attached to the rear surface (back surface) of the above-mentioned piston 101. The belt conveyor 60 is mainly configured to have an endless conveyor belt 601, to which a weight 61 is attached, and which is disposed along a direction perpendicular or substantially perpendicular to the axis of the piston pin 1011 when viewed from the axial direction of the piston 101, and an electric motor 603 which drives and rotates the conveyor belt 601.

[0022] When viewed from the axial direction of the piston 101, the belt conveyor 60 moves the weight 61 in a direction perpendicular or substantially perpendicular to the axis of the piston pin 1011 (changing the position of the center of gravity of the piston 101) between a region including the center of gravity of the piston and a region not including the center of gravity of the piston (thrust side and anti-thrust side), with the axis of the piston pin 1011 swingably connecting the piston 101 and the small end of the connecting rod 102 as the boundary. That is, the weight 61 is advanced or returned (returned to its original position) in a direction perpendicular or substantially perpendicular to the axis of the piston pin 1011 by the belt conveyor 60 (electric motor 603). Note that the initial position (default position) of the weight 61 is set, for example, on the axis of the crank pin.

[0023] The weight (mass) 61 has a predetermined mass, i.e., a mass (for example, about several tens of grams) that can offset the offset of the piston center of gravity. The weight 61 may have any shape, for example, a rectangular parallelepiped shape. The weight 61 may also be made of any material, but is preferably made of a metal such as iron, taking into consideration heat resistance, oil resistance, etc.

[0024] Here, the rotating shaft 602 of the conveyor (roller) is held (rotatably supported) on the inner surface of the piston 101. The belt conveyor 60 is installed offset in the axial direction of the piston pin 1011 so as to avoid the connecting rod 102. Offsetting the belt conveyor 60 changes the position of the center of gravity of the piston, but the shift in the axial direction of the piston pin 1011 does not affect the piston slapping noise. If a bifurcated connecting rod (a connecting rod with a bifurcated piston side) is used, the belt conveyor 60 can be placed between the bifurcated connecting rods (at the center of the piston 101).

[0025] However, the configuration (mechanism) for linearly moving the weight 61 is not limited to the belt conveyor 60. Instead of the above-described belt conveyor 60, for example, a rack-and-pinion configuration in which a small gear (pinion) and a plate-shaped gear (rack) are combined, or a worm gear (worm shaft) in which a screw gear (worm) and a meshing helical gear (worm wheel) are combined may be used. Also, for example, a system in which a ball screw is rotated by a feed motor and converted into linear motion may be employed. Furthermore, the weight 61 may be directly and linearly driven by a linear motor, a linear solenoid, or the like.

[0026] Furthermore, for example, a first wireless communication unit 71 is attached to a side surface of the crankcase 104 (more specifically, to the side of a second wireless communication unit 72 described later, etc.) to transmit control information including target rotation angle information of the electric motor 603. The first wireless communication (transmission / reception) unit 71 is connected to an engine control unit (hereinafter referred to as "ECU") 50 described later, and transmits control information including target rotation angle information (target rotation direction, target rotation angle, etc.) of the electric motor 603 output from the ECU 50.

[0027] Meanwhile, a second wireless communication (transmission / reception) unit 72 is disposed (attached) inside the crankcase 104 (more specifically, on a side surface of the base end of the connecting rod 102, or the like) and receives control information including target rotation angle information for the electric motor 603 transmitted from the first wireless communication unit 71. Also disposed inside the crankcase 104 (more specifically, for example, integrally with the second wireless communication unit 72) is a motor driver 73 that drives the electric motor 603 (belt conveyor 60) based on control information including target rotation angle information (rotation direction and rotation angle) for the electric motor 603 received by the second wireless communication unit 72.

[0028] Furthermore, a contactless charger 80 is disposed inside the crankcase 104 to charge a battery 83 that supplies power to the electric motor 603. More specifically, the contactless charger 80 is composed of a primary side contactless charging module (power transmitting side module) 801 and a secondary side contactless charging module (power receiving side module) 802, and uses electromagnetic induction to transmit power contactlessly (wirelessly).

[0029] The power transmitting module 801 is disposed, for example, on the bottom (bottom surface) of the crankcase (oil pan) 104 so as to be able to face the power receiving module 802, and transmits power to the power receiving module 802. The power transmitting module 801 is configured to include, for example, a power transmitting coil that receives AC power from the inverter and generates an AC magnetic field, a resonant capacitor that is connected to the power transmitting coil and forms a power transmitting LC resonant circuit together with the power transmitting coil, and a magnetic member that is disposed on the rear side of the power transmitting coil and reduces the magnetic resistance of the magnetic path and enhances magnetic coupling between the coils. The inverter converts power supplied from an external power source into AC power corresponding to a resonant frequency and applies the AC power to the power transmitting coil. The drive of the inverter is controlled by the ECU 50.

[0030] The power receiving module 802 is attached to, for example, the bottom surface (lower end) of the connecting rod 102 so as to be able to face the power transmitting module 801, and receives power transmitted from the power transmitting module 801. The power receiving module 802 is configured to include, for example, a power receiving coil that receives power from the power transmitting coil via an AC magnetic field generated by the power transmitting coil, a resonant capacitor that is connected to the power receiving coil and forms a power receiving LC resonant circuit together with the power receiving coil, and a magnetic member that is arranged on the back side of the power receiving coil and reduces the magnetic resistance of the magnetic path and enhances magnetic coupling between the coils. The AC power received by the power receiving module 802 (power receiving coil) is converted to DC power by a rectifier circuit and regulator circuit and output to the battery 83 (i.e., the battery 83 is charged).

[0031] The battery 83 and the motor driver 73, and the motor driver 73 and the electric motor 603 are electrically connected by wiring (wire harness) 85. The wiring (wire harness) 85 is fixed with, for example, a resin (potting material) that is heat-resistant, oil-resistant, etc., so that it does not move wildly due to the movement of the connecting rod 102 or the piston 101.

[0032] In addition to the air flow meter 14, air-fuel ratio sensor 37, and throttle opening sensor 35 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.

[0033] 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.

[0034] 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.

[0035] These sensors are connected to the 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 operation amount sensor 34 that detects the amount of depression of the accelerator pedal, i.e., the operation amount of the accelerator pedal, and a vehicle speed sensor 36 that detects the speed of the vehicle.

[0036] The ECU 50 is configured to include 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 in which the stored contents are maintained by a battery or the like, 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.

[0037] 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 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.

[0038] 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 603. The ECU 50 functions as a control unit as defined in the claims.

[0039] 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.

[0040] Therefore, the ECU 50 controls the belt conveyor 60 (electric motor 603) to adjust the position of the weight 61 based on the degree of engine vibration corresponding to the piston smacking sound (piston smacking sound level). More specifically, when the piston smacking sound level is equal to or greater than a predetermined threshold value, the ECU 50 controls the belt conveyor 60 (electric motor 603) to move the weight 61 to a region (anti-thrust side) that does not include the center of gravity of the piston, with the axis of the piston pin 1011 as the boundary.

[0041] 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.

[0042] As described above, when the piston slapping sound level is equal to or greater than a predetermined threshold, the ECU 50 controls the belt conveyor 60 (electric motor 603) to move the weight 61 to an area not including the piston center of gravity (on the anti-thrust side). That is, the ECU 50 moves the weight 61 so as to cancel (offset) the offset of the piston center of gravity, thereby bringing the piston center of gravity onto the axis of the piston pin 1011. As a result, the moment around the piston pin becomes zero (or approximately zero), and oscillation (tilting) of the piston 101 is suppressed.

[0043] 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.

[0044] Next, the ECU 50 learns the rotation angle (motor rotation angle) of the electric motor 603 at which the piston slap sound level takes on a minimum value in the learned engine operating state (piston slap sound countermeasure region), as shown in Fig. 4. Fig. 4 is a diagram for explaining a method for learning the minimum value of the rotation angle of the electric motor 603 (a method for searching for the minimum value) by the engine control device 1. Note that a known method (algorithm) can be used as a method for searching for the rotation angle of the electric motor 603 at which the piston slap sound level takes on a minimum value.

[0045] Here, the rotation angle of the electric motor 603 correlates with the drive amount (movement amount) of the belt conveyor 60, and the drive amount (movement amount) of the belt conveyor 60 correlates with the movement amount (position) of the weight 61. Therefore, the rotation angle of the electric motor 603 correlates with the position of the weight 61.

[0046] As the rotation angle of electric motor 603, target rotation angle information of electric motor 603 obtained within ECU 50 can be used. However, a sensor such as a rotary encoder that detects the rotation angle of electric motor 603 may be provided, and the detected value (actual rotation angle) of the sensor may be used. Alternatively, a sensor (current sensor or voltage sensor) that detects the applied current or applied voltage of electric motor 603 may be provided, and the rotation angle of electric motor 603 may be estimated from the detected value of the sensor. When the actual rotation angle, applied current, or applied voltage of electric motor 603 is used, data (detected value) detected by the sensor is transmitted from second wireless communication unit 72 to first wireless communication unit 71 (transmitted from inside to outside of crankcase 104) and read into ECU 50.

[0047] The ECU 50 generates a motor rotation angle map (lookup table) that defines the relationship between the learned multiple engine operating conditions (engine speed, engine load) and the learned rotation angles of the multiple electric motors 603 for each of the multiple engine operating conditions (regions).

[0048] After learning the rotation angle of the electric motor 603 (after generating the motor rotation angle map), if the engine is in an operating state (piston hammering noise countermeasure area) where the piston hammering noise level is equal to or greater than a predetermined threshold, the ECU 50 uses the motor rotation angle map to control the rotation angle of the electric motor 603 (belt conveyor 60) (i.e., adjusts the position of the weight 61).

[0049] That is, the ECU 50 stores a map (motor rotation angle map) that defines the relationship between the engine speed, engine load, and rotation angle of the electric motor 603 in an EEPROM or the like, and searches this motor rotation angle map based on the detected engine speed and engine load to determine the target rotation angle of the electric motor 603. Then, based on the target rotation angle, the ECU 50 adjusts (controls) the rotation angle of the electric motor 603 (belt conveyor 60) in real time.

[0050] An example of the motor rotation angle map is shown in Fig. 3. In Fig. 3, the horizontal axis represents engine speed (rpm) and the vertical axis represents engine load (g / rev). In the motor rotation angle map, a learned rotation angle of electric motor 603 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 motor rotation angle map, the rotation angle of electric motor 603 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) where the piston slapping noise level is equal to or greater than a predetermined threshold value) shown by the shaded area in Fig. 3.

[0051] Next, the operation of the engine control device 1 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a flowchart showing the processing procedure of piston slap noise reduction control (part 1: piston slap noise countermeasure area learning processing) by the engine control device 1. Fig. 6 is a flowchart showing the processing procedure of piston slap noise reduction control (part 2: piston slap noise minimization motor rotation angle learning processing) by the engine control device 1. This processing is repeatedly executed at a predetermined timing by the ECU 50.

[0052] First, the learning process of the piston slap noise countermeasure region will be described with reference to Fig. 5. 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 regions. If learning has been completed for all engine operating regions (map grids) as to whether or not they are piston slap noise countermeasure regions, the process proceeds to step S200 (learning process of the motor rotation angle for minimizing piston slap noise). 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 region, the process proceeds to step S102.

[0053] 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.

[0054] 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).

[0055] 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.

[0056] 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.

[0057] 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 motor rotation angle learning process.

[0058] 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 motor rotation angle learning process.

[0059] Next, the learning process of the motor rotation angle for minimizing piston slap sounds will be described with reference to Fig. 6. In step S200, it is determined whether or not the motor rotation angle for minimizing piston slap sounds has been learned for all piston slap sound countermeasure areas (map grids). If the motor rotation angle for minimizing piston slap sounds has been learned for all piston slap sound countermeasure areas (map grids), the process proceeds to step S300. On the other hand, if there is a piston slap sound countermeasure area (map grid) for which the motor rotation angle for minimizing piston slap sounds has not been learned, the process proceeds to step S202.

[0060] In step S202, it is determined whether the current engine operating state (engine speed, engine load) is in an engine operating state (piston slapping countermeasure region) where piston slapping countermeasures are required. If the engine operating state (region) is such that piston slapping countermeasures are not required, the weight 61 is returned to its initial position (for example, a position on the axis of the crank pin) in step S302, and then the process temporarily exits. On the other hand, if the engine operating state is such that piston slapping countermeasures are required (piston slapping countermeasure region), the process proceeds to step S204.

[0061] In step S204, it is determined whether or not the motor rotation angle 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 weight 61 is returned to the initial position 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.

[0062] In step S206, the belt conveyor 60 (electric motor 603) is controlled to move the weight 61 to a region (anti-thrust side) that does not include the center of gravity of the piston, with the axis of the piston pin 1011 as the boundary.

[0063] 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).

[0064] 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.

[0065] Next, in step S214, it is determined whether the piston slap sound level has reached a minimum value (i.e., whether the motor rotation angle is 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 electric motor 603 (i.e., the position of the weight 61) is changed, and the processes of steps S206 to S214 described above are executed again.

[0066] In step S216, the current motor rotation angle is learned as the motor rotation angle at which the piston slapping noise level takes the minimum value in the current piston slapping noise countermeasure region (map grid).

[0067] Next, in step S218, it is determined whether the motor rotation angles that minimize piston slap sounds have been learned for all piston slap sound countermeasure regions (map grids). If the motor rotation angles that minimize piston slap sounds have been learned for all piston slap sound countermeasure regions (map grids), the process proceeds to step S300. On the other hand, if there is a piston slap sound countermeasure region (map grid) for which the motor rotation angles that minimize piston slap sounds have not been learned, the weight 61 is returned to its initial position in step S302, and then the process temporarily exits.

[0068] In step S300, the rotation angle of the electric motor 603 (belt conveyor 60) is controlled (the position of the weight 61 is adjusted) using the learned motor rotation angle map. After that, the process temporarily exits from this process.

[0069] As described above in detail, according to this embodiment, when the piston slap noise level is equal to or greater than a predetermined threshold, the weight 61 having a predetermined mass is moved to a region that does not include the piston center of gravity, with the axis of the piston pin 1011 as the boundary, as viewed from the axial direction of the piston 101. Therefore, by moving the weight 61 so as to cancel (offset) the offset of the piston center of gravity, it is possible to bring (change) the piston center of gravity onto the axis of the piston pin 1011. This makes it possible to make the moment around the piston pin zero (or approximately zero). In other words, it is possible to make the inclination of the piston 101 zero (or approximately zero). 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.

[0070] 7 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 top dead center of compression). In FIG. 7, the dashed line shows the piston behavior when there is no weight 61, belt conveyor 60, or the like, or when the weight 61 is not moved (when the center of gravity of the piston is not changed).

[0071] 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).

[0072] According to this embodiment, the belt conveyor 60 includes an endless conveyor belt 601, to which a weight 61 is attached, that is disposed along a direction perpendicular to the axis of the piston pin 1011, and an electric motor 603 that rotates and drives the conveyor belt 601. Therefore, when viewed from the axial direction of the piston 101, the weight 61 can be moved in a direction perpendicular to the axis of the piston pin 1011 between a region that includes the center of gravity of the piston and a region that does not include the center of gravity of the piston, with the axis of the piston pin 1011 as the boundary.

[0073] 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 electric motor 603 in which the piston slap noise level is minimized in the learned engine operating state (piston slap noise countermeasure region) is learned. After the motor rotation angle is learned, when the engine is in the learned engine operating state (piston slap noise countermeasure region), the rotation angle of the belt conveyor 60 (electric motor 603) is controlled (the position of the weight 61 is adjusted) based on the learned motor rotation angle. This eliminates the need for engine adaptation, which involves tuning control constants related to piston slap noise reduction in advance, thereby reducing the amount of adaptation work required. Furthermore, individual variations in the engine 10 can be eliminated (absorbed).

[0074] Furthermore, according to this embodiment, a motor rotation angle map is generated that defines the relationship between a plurality of learned engine operating states (piston slap noise countermeasure regions) and a plurality of learned rotation angles of the electric motor 603 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 learned motor rotation angle map is used to control the rotation angle of the belt conveyor 60 (electric motor 603) (adjust the position of the weight 61). 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.

[0075] According to this embodiment, the engine operating state (operating condition) is determined by the engine speed and the engine load, so that the operating state that increases the piston slapping noise can be appropriately determined.

[0076] Furthermore, according to this embodiment, there are provided a first wireless communication unit 71 that transmits target rotation angle information and the like of the electric motor 603, a second wireless communication unit 72 that is disposed inside the crankcase 104 and receives the target rotation angle information and the like of the electric motor 603 transmitted from the first wireless communication unit 71, a motor driver 73 that is disposed inside the crankcase 104 and drives the electric motor 603 based on the target rotation angle information and the like of the electric motor 603 received by the second wireless communication unit 72, and a contactless charger 80 that is disposed inside the crankcase 104 and charges a battery 83 that supplies power to the electric motor 603. Therefore, the belt conveyor 60 (electric motor 603) disposed inside the crankcase 104 can be operated (controlled) from outside the crankcase 104.

[0077] 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 an in-line engine 10, but the present invention can also be applied to engines such as horizontally opposed or V-type engines. In addition, in the above embodiments, the present invention has been described as being applied to a direct-injection engine 10, but the present invention can also be applied to a port-injection engine. Furthermore, in the above embodiments, the present invention has been applied to a conventional (gasoline) engine vehicle, but the present invention can also be applied to an engine installed in a hybrid electric vehicle (HEV) that has an engine and an electric motor as a driving power source, for example.

[0078] In the above embodiment, the belt conveyor 60 is installed offset in the axial direction of the piston pin 1011 so as to avoid the connecting rod 102. However, a bifurcated connecting rod (a connecting rod with a bifurcated piston side) may be used, and the belt conveyor 60 may be arranged between the bifurcated connecting rods (i.e., at the center of the piston 101).

[0079] In the above embodiment, the belt conveyor 60 is used as a configuration (mechanism) for linearly moving the weight 61, but instead of the belt conveyor 60, a configuration (mechanism) using, for example, a rack and pinion, a worm gear, a ball screw, a linear motor, a linear solenoid, or the like may also be employed. In addition, the material, shape, etc. of the belt conveyor 60 can be changed as desired depending on requirements such as heat resistance and oil resistance, for example.

[0080] Furthermore, the method of searching for the minimum point (value) of the rotation angle of the electric motor 603 is not limited to the above embodiment, and any suitable method (algorithm) can be adopted. [Explanation of symbols]

[0081] 1 Engine control device 10 Engine 101 Piston 1011 Piston pin 102 Connecting rod 103 cylinder 104 Crankcase 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 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 50 ECU 60 Conveyor Belt 601 Conveyor Belt 602 Rotation axis 603 Electric Motor 61 Weight (mass) 71 first wireless communication unit 72 second wireless communication unit 73 Motor Driver 80 contactless charger 801 Primary side contactless charging module (power transmission side module) 802 Secondary side contactless charging module (receiving side module) 83 Battery 85 Wiring (wire harness)

Claims

1. a vibration detection means for detecting engine vibrations corresponding to piston smacking sounds; a weight having a predetermined mass and movably attached to the back of the piston; a moving means for moving the weight between a region including the center of gravity of the piston and a region not including the center of gravity of the piston, with the axis of the piston pin as the boundary, as viewed from the axial direction of the piston; a control unit that controls the moving means based on the degree of engine vibration corresponding to the piston slapping sound detected by the vibration detection means, the control unit controls the moving means to move the weight to an area that does not include the center of gravity of the piston when a degree of engine vibration corresponding to a piston smacking sound is equal to or greater than a predetermined threshold.

2. The moving means is an endless conveyor belt to which the weight is attached and which is disposed along a direction perpendicular to the axis of the piston pin; an electric motor that rotates and drives the conveyor belt; 2. The engine control device according to claim 1, wherein the engine control device is a belt conveyor having:

3. 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 a rotation angle of the electric motor at which the degree of engine vibration corresponding to piston slap noise takes a minimum value in the learned engine operating state; After learning the rotation angle of the electric motor, when the engine is in the learned operating state, the belt conveyor is controlled based on the learned rotation angle of the electric motor.

3. The engine control device according to claim 2.

4. The control unit generating a rotation angle map that defines a relationship between the plurality of learned engine operating states and the plurality of learned rotation angles of the electric motor for each of the plurality of engine operating states; When the engine is in the learned operating state, the belt conveyor is controlled using the rotation angle map.

4. The engine control device according to claim 3.

5. a first wireless communication unit electrically connected to the control unit and configured to transmit control information including target rotation angle information of the electric motor; a second wireless communication unit disposed inside the crankcase and configured to receive control information including target rotation angle information of the electric motor transmitted from the first wireless communication unit; a motor driver disposed inside the crankcase and configured to drive the electric motor based on control information including target rotation angle information of the electric motor received by the second wireless communication unit; 5. The engine control device according to claim 4, further comprising a contactless charger disposed inside the crankcase for charging a battery that supplies power to the electric motor.

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