Internal combustion engine control device and internal combustion engine control method

Abstract

To provide an internal combustion engine control device and an internal combustion engine control method, which can determine fuel properties in a transition period in which different types of fuel are replaced.SOLUTION: An internal combustion engine control device controls an internal combustion engine that is provided with a fuel pump for supplying fuel to a common rail, and a fuel injection device for injecting the fuel within the common rail into a combustion chamber. The internal combustion engine control device comprises a fuel balance calculation unit, a property estimation unit, and a parameter setting unit. The fuel balance calculation unit calculates a fuel balance, which is the difference between the amount of fuel supplied by the fuel pump and the amount of fuel reduced by the injection of the fuel injection device. The property estimation unit estimates fuel properties in accordance with the fuel balance. The parameter setting unit sets a control parameter for controlling the internal combustion engine on the basis of the fuel properties.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine control device and an internal combustion engine control method. [Background technology]

[0002] In recent years, alcohol fuels, such as biofuels, have become increasingly popular in order to reduce the use of fossil fuels. Furthermore, technology has been developed to synthesize carbon dioxide and hydrogen using renewable energy to produce new synthetic fuels. This has led to an increasing demand for technology that allows alcohol fuels or synthetic fuels to be mixed with gasoline and burned in internal combustion engines.

[0003] Alcohol fuels and synthetic fuels have different physical properties than gasoline, such as evaporation rate and theoretical air-fuel ratio. Furthermore, because alcohol fuels and synthetic fuels have different compositions than gasoline, they may produce harmful substances during incomplete combustion. Therefore, internal combustion engines require appropriate control when burning gasoline blended with alcohol fuel or synthetic fuel.

[0004] With the spread of biofuels and synthetic fuels, internal combustion engines require appropriate fuel injection control for various fuel mixtures. Therefore, when a different type of fuel is refueled from the previous fuel, the internal combustion engine control device must quickly estimate the fuel.

[0005] Patent Document 1 discloses a fuel supply control device that controls the operation of a fuel pump. The fuel supply control device disclosed in Patent Document 1 estimates the alcohol fuel concentration of the supplied fuel based on the rate of increase in pressure of the feed pump, which changes depending on the viscosity of the fuel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-203813 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the fuel supply control device described in Patent Document 1 estimates the alcohol fuel concentration under the assumption that the fuel system is filled with new fuel. Therefore, when estimating the alcohol fuel concentration, the fuel supply control device described in Patent Document 1 does not take into account the influence of the fuel remaining in the fuel tank before refueling.

[0008] In consideration of the above problems, an object of the present invention is to provide an internal combustion engine control device and an internal combustion engine control method that are capable of determining fuel properties during a transition period when different types of fuel are being replaced. [Means for solving the problem]

[0009] To solve the above problems and achieve the present object, one aspect of the present invention provides an internal combustion engine control device that controls an internal combustion engine equipped with a fuel pump that supplies fuel to a common rail and a fuel injection device that injects fuel from the common rail into a combustion chamber. The internal combustion engine control device includes a fuel balance calculation unit, a property estimation unit, and a parameter setting unit. The fuel balance calculation unit calculates the fuel balance, which is the difference between the amount of fuel supplied by the fuel pump and the amount of fuel reduced by injection by the fuel injection device. The property estimation unit estimates the fuel property based on the fuel balance. The parameter setting unit sets control parameters for controlling the internal combustion engine based on the fuel property.

[0010] One aspect of the present invention is a method for controlling an internal combustion engine including a fuel pump that supplies fuel to a common rail and a fuel injection device that injects fuel from the common rail into a combustion chamber. In the method, a fuel balance calculation unit calculates a fuel balance, which is the difference between the amount of fuel supplied by the fuel pump and the amount of fuel reduced by injection from the fuel injection device. Next, a property estimation unit estimates fuel properties based on the fuel balance. Next, a parameter setting unit sets control parameters for controlling the internal combustion engine based on the fuel properties. [Effects of the Invention]

[0011] According to the internal combustion engine control device and the internal combustion engine control method configured as described above, it is possible to determine the fuel properties during a transition period when different types of fuel are being replaced. Problems, configurations, and effects other than those described above will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an overall configuration diagram showing an internal combustion engine according to a first embodiment. [Figure 2] 1 is a diagram showing an example of a fuel supply path including a fuel pump according to a first embodiment. [Figure 3] FIG. 2 is a block diagram showing the functional configuration of an engine control unit according to the first embodiment. [Figure 4] FIG. 2 is a block diagram showing the functional configuration of an engine control unit according to the first embodiment. [Figure 5] FIG. 2 is a block diagram showing the functional configuration of an engine control unit according to the first embodiment. [Figure 6] FIG. 3 is a diagram showing the drive timing of the fuel pump according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing the relationship between the drive timing of the fuel pump and fuel viscosity according to the first embodiment. [Figure 8] FIG. 10 is a schematic diagram showing the configuration of a plug-in hybrid vehicle according to a second embodiment. [Figure 9] FIG. 10 is a diagram illustrating a functional configuration of an engine controller according to a second embodiment. [Figure 10] 10 is a flowchart showing an example of a fuel property determination process according to the second embodiment. [Figure 11] FIG. 10 is a diagram showing the relationship between the target fuel pressure and the actual fuel pressure of the fuel pump according to the second embodiment and the fuel viscosity. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and redundant description will be omitted.

[0014] 1. First embodiment An internal combustion engine according to a first embodiment of the present invention will be described below. Note that common members are denoted by the same reference numerals in the various drawings.

[0015] [Internal combustion engine] First, an example of the configuration of the internal combustion engine according to this embodiment will be described. FIG. 1 is a diagram showing the overall configuration of an internal combustion engine according to this embodiment.

[0016] 1 is a four-stroke engine that repeats four strokes: an intake stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke, and is a multi-cylinder engine having, for example, four cylinders. Note that the number of cylinders that the internal combustion engine 100 has is not limited to four, and it may have six, eight, or more cylinders.

[0017] The internal combustion engine 100 has a combustion chamber 104. The combustion chamber 104 is formed by a cylinder head 101, a cylinder block 102, and a piston 103. The piston 103 is inserted into the cylinder block 102. An intake pipe 105 and an exhaust pipe 106 are connected to the cylinder head 101. The intake pipe 105 and the exhaust pipe 106 are each connected to the combustion chamber 104.

[0018] An intake valve 107 is disposed at the communication portion between the intake pipe 105 and the combustion chamber 104. The intake valve 107 operates as a cam rotates, opening and closing the communication portion between the intake pipe 105 and the combustion chamber 104. An exhaust valve 108 is disposed at the communication portion between the exhaust pipe 106 and the combustion chamber 104. The exhaust valve 108 operates as a cam rotates, opening and closing the communication portion between the exhaust pipe 106 and the combustion chamber 104.

[0019] The piston 103 is connected to a crankshaft 115 via a connecting rod 114. The reciprocating motion of the piston 103 is converted into rotational motion by the crankshaft 115. A starter motor (not shown) is connected to the crankshaft 115. When starting the engine, the starter motor rotates the crankshaft 115.

[0020] A crank angle sensor 116 is attached near the crankshaft 115. The crank angle sensor 116 detects the rotation and phase of the crankshaft 131 and outputs the detection results to an ECU (engine control unit) 118. The ECU 118 detects the number of rotations and rotation speed of the internal combustion engine 100 based on the output of the crank angle sensor 116. The ECU 118 corresponds to the internal combustion engine control device according to the present invention.

[0021] A water temperature sensor 117 is attached to the cylinder block 102. The water temperature sensor 117 detects the temperature of the cooling water that cools the cylinder block 102. The water temperature sensor 117 outputs the detected temperature of the cooling water to the ECU 118.

[0022] A collector and an intake air temperature sensor (not shown) are arranged upstream of the intake pipe 105. The collector is a branching part that distributes air to each combustion chamber 104. The intake air temperature sensor detects the temperature of the air taken into the combustion chamber 104 (intake air temperature). The intake air temperature sensor outputs the detected intake air temperature to the ECU 118.

[0023] An airflow sensor and a throttle valve (not shown) are arranged upstream of the collector. The throttle valve changes its opening to adjust the amount of air taken into the combustion chamber 104. The airflow sensor detects the amount of air taken into the combustion chamber 104 (intake air amount). The airflow sensor outputs the detected intake air amount to the ECU 118.

[0024] The fuel tank 109 stores fuel. The internal combustion engine 100 of this embodiment can use a blended fuel of alcohol fuel and gasoline fuel. Therefore, the fuel stored in the fuel tank 109 is, for example, a blended fuel of alcohol fuel and gasoline fuel.

[0025] A fuel gauge (not shown) and a feed pump 110 are housed inside the fuel tank 109. The fuel gauge detects the amount of fuel stored in the fuel tank 109. The fuel gauge outputs the detected amount of fuel to the ECU 118. The feed pump 110 pressurizes the fuel in the fuel tank 109 to about 0.3 MPa and sends it to the high-pressure fuel pump 111.

[0026] A high-pressure fuel pump (fuel pump) 111 increases the pressure of the supplied fuel and sends it to a common rail 112. The high-pressure fuel pump 111 increases the pressure of the fuel to, for example, about 30 MPa. A fuel injector 119 is connected to the common rail 112. The fuel injector 119 directly injects fuel into the combustion chamber 104.

[0027] A fuel pressure sensor 113 is attached to common rail 112. Fuel pressure sensor 113 detects the pressure (actual fuel pressure) of the fuel in common rail 112. Fuel pressure sensor 113 outputs the detected actual fuel pressure value to ECU 118. Fuel pressure sensor 113 corresponds to a fuel pressure detection unit according to the present invention.

[0028] [Fuel supply system] Next, the overall configuration of the fuel supply system including the high-pressure fuel pump 111 will be described with reference to FIG. FIG. 2 is a diagram showing an example of a fuel supply path including a high-pressure fuel pump 111. As shown in FIG.

[0029] 2, the fuel supply system includes a high-pressure fuel pump 111, an ECU 118, a fuel tank 109, a common rail 112, and a plurality of fuel injection devices 119. The components of the high-pressure fuel pump 111 are integrally incorporated into a pump body 1 (hereinafter referred to as "body 1").

[0030] Fuel in fuel tank 109 is pumped up by feed pump 110, which is driven based on a signal sent by ECU 118. The pumped up fuel is pressurized to an appropriate pressure by a pressure regulator (not shown) and sent to low-pressure fuel intake port 51 of high-pressure fuel pump 111 through low-pressure piping 120.

[0031] The high-pressure fuel pump 111 pressurizes fuel supplied from the fuel tank 109 and sends it under pressure to a common rail 112. The plurality of fuel injectors 119 corresponds to the number of cylinders (combustion chambers 104). The plurality of fuel injectors 119 inject fuel in accordance with a drive current output from an ECU 118. The fuel supply system of this embodiment is a so-called direct injection engine system in which the fuel injectors 119 inject fuel directly into the combustion chambers 104 of the engine.

[0032] The ECU 118 calculates an appropriate amount of fuel to be injected (target amount of fuel to be injected) and an appropriate fuel pressure (target fuel pressure) based on engine state quantities (e.g., crank angle, throttle opening, engine speed, fuel pressure, etc.) obtained from various sensors. For example, the engine speed can be calculated from the output signal of the crank angle sensor 116. The amount of intake air flowing into the cylinder can be calculated from the output signal of the air flow sensor. The ECU 118 controls the operation of the high-pressure fuel pump 111 and the fuel injection device 119 based on the calculation results.

[0033] Based on the calculation results of the target fuel pressure, the target injection fuel amount, etc., the ECU 118 controls the driving of the high-pressure fuel pump 111 and the plurality of fuel injection devices 119. That is, the ECU 118 has a pump control unit that controls the high-pressure fuel pump 111 and an injector control unit that controls the fuel injection device 119.

[0034] The high-pressure fuel pump 111 has a pressure pulsation reducing mechanism 9, an electromagnetic intake valve mechanism (solenoid valve mechanism) 3 which is a variable displacement mechanism, a discharge valve mechanism 8, and a relief valve mechanism. Fuel flowing in from a low-pressure fuel intake port 51 reaches an intake port 31b of the electromagnetic intake valve mechanism 3 through the pressure pulsation reducing mechanism 9 and an intake passage 10b.

[0035] Fuel that flows into the intake port 31b of the electromagnetic intake valve mechanism 3 passes through the intake valve 32, flows through an intake passage 1a formed in the body 1, and then flows into the pressurizing chamber 11. A plunger 2 is slidably held in the pressurizing chamber 11. The plunger 2 reciprocates when power is transmitted by a cam mechanism (not shown) of the engine.

[0036] In the pressurization chamber 11, fuel is drawn in through the electromagnetic intake valve mechanism 3 during the downward stroke of the plunger 2, and the fuel is pressurized during the upward stroke. When the fuel pressure in the pressurization chamber 11 exceeds a predetermined value, the discharge valve mechanism 8 opens, and the high-pressure fuel is pumped through the fuel discharge port 12a to the common rail 112. The discharge of fuel by the high-pressure fuel pump 111 is controlled by opening and closing the electromagnetic intake valve mechanism 3. The opening and closing of the electromagnetic intake valve mechanism 3 is controlled by the ECU 118. The injection of fuel by the fuel injector 119 is controlled by the ECU 118.

[0037] [ECU functional configuration] Next, the functional configuration of the ECU 118 will be described with reference to FIGS. 3 to 5 are block diagrams showing the functional configuration of ECU 118. As shown in FIG.

[0038] 3, ECU 118 has a driving operation detection unit 301, an engine speed calculation unit 302, a cylinder inflow air amount calculation unit 303, and a target throttle opening calculation unit 304. Furthermore, ECU 118 has a target fuel pressure calculation unit 305, a fuel pressure feedback correction coefficient calculation unit 306, and a high-pressure fuel pump drive unit 307.

[0039] An accelerator position sensor is provided in the vehicle. The accelerator position sensor detects the displacement of the accelerator pedal operated by the driver and sends an accelerator position signal representing the detection result to ECU 118. The accelerator position signal output by the accelerator position sensor is input to driving performance detection unit 301. Driving performance detection unit 301 calculates the accelerator opening based on the accelerator position signal.

[0040] The crank angle sensor signal output by crank angle sensor 116 is input to engine speed calculation unit 302. Engine speed calculation unit 302 detects periodic amplitude changes in the crank angle sensor signal and counts the number of inputs per unit time. As a result, engine speed calculation unit 302 calculates the number of engine revolutions per unit time, i.e., the engine speed.

[0041] The cylinder inflow air amount calculation unit 303 receives the intake air amount sensor signal output by the air flow sensor, the intake pipe pressure sensor signal output by the intake pipe pressure sensor installed in the intake pipe 105, and the engine speed calculated by the engine speed calculation unit 302. The cylinder inflow air amount calculation unit 303 calculates the cylinder inflow air amount based on the intake air amount sensor signal and the intake pipe pressure sensor signal. Furthermore, the cylinder inflow air amount calculation unit 303 calculates the engine load based on the cylinder inflow air amount and the engine speed.

[0042] The target throttle opening calculation unit 304 calculates the required target torque based on the accelerator opening and engine speed, and then calculates the target throttle opening from the target torque.

[0043] The engine speed calculated by engine speed calculation unit 302, the engine load calculated by cylinder inflow air amount calculation unit 303, and fuel properties (described later) are input to target fuel pressure calculation unit 305. Target fuel pressure calculation unit 305 calculates a target fuel pressure value based on the engine speed, engine load, and fuel properties.

[0044] The fuel pressure sensor signal output by fuel pressure sensor 113, the target fuel pressure value calculated by target fuel pressure calculation unit 305, and fuel properties, which will be described later, are input to fuel pressure feedback correction coefficient calculation unit 306. Fuel pressure feedback correction coefficient calculation unit 306 calculates a fuel pressure feedback correction coefficient based on the fuel pressure sensor signal, the target fuel pressure value, and the fuel properties. The fuel pressure feedback correction coefficient is a correction coefficient used by high-pressure fuel pump drive unit 307 when correcting the target fuel pressure.

[0045] The fuel pressure feedback correction coefficient calculated by the fuel pressure feedback correction coefficient calculation unit 306 is input to the high-pressure fuel pump drive unit 307. The high-pressure fuel pump drive unit 307 controls the drive of the high-pressure fuel pump 111 to cause the high-pressure fuel pump 111 to discharge the fuel discharge amount corresponding to the fuel pressure feedback correction coefficient.

[0046] 4, the ECU 118 has a basic fuel amount calculation unit 308, a basic ignition timing calculation unit 309, an ISC (idle speed control) control unit 310, an air-fuel ratio feedback correction coefficient calculation unit 311, and a target air-fuel ratio calculation unit 312. Furthermore, the ECU 118 has a fuel amount correction unit 313, a fuel injection valve drive unit 314, an ignition timing correction unit 315, and an ignition module drive unit 316.

[0047] The engine speed calculated by the engine speed calculation unit 302, the engine load calculated by the cylinder inflow air amount calculation unit 303, and fuel properties (described later) are input to the basic fuel amount calculation unit 308. The basic fuel amount calculation unit 308 calculates the basic fuel amount based on the engine speed, engine load, and fuel properties. The basic fuel amount is the amount of fuel required by the engine in each operating range.

[0048] The engine speed calculated by the engine speed calculation unit 302, the engine load calculated by the cylinder inflow air amount calculation unit 303, and fuel properties (described later) are input to the basic ignition timing calculation unit 309. The basic ignition timing calculation unit 309 calculates the basic ignition timing of the engine in each operating range based on the engine speed, engine load, and fuel properties.

[0049] The engine speed calculated by engine speed calculation unit 302 and the water temperature sensor signal output by water temperature sensor 117 are input to ISC control unit 310. ISC control unit 310 controls the engine idling speed based on the engine speed and the water temperature sensor signal. In order to keep the engine idling speed constant, ISC control unit 310 calculates a target engine speed during idling and a target intake air amount.

[0050] The engine speed calculated by the engine speed calculation unit 302, the engine load calculated by the cylinder inflow air amount calculation unit 303, and fuel properties (described later) are input to the target air-fuel ratio calculation unit 312. The target air-fuel ratio calculation unit 312 calculates a target air-fuel ratio based on the engine speed, engine load, and fuel properties. The target air-fuel ratio is a target value for the air-fuel ratio of the engine.

[0051] The engine speed calculated by the engine speed calculation unit 302, the air-fuel ratio sensor signal output by the air-fuel ratio sensor, fuel properties described below, and the target air-fuel ratio calculated by the target air-fuel ratio calculation unit 312 are input to the air-fuel ratio feedback correction coefficient calculation unit 311. The air-fuel ratio sensor is installed in the exhaust pipe 106.

[0052] An air-fuel ratio feedback correction coefficient calculation unit 311 calculates an air-fuel ratio feedback correction coefficient based on the difference between the air-fuel ratio sensor signal and the target air-fuel ratio, the engine speed, the engine load, and the fuel properties. The air-fuel ratio feedback correction coefficient is a correction coefficient used by a fuel amount correction unit 313 when correcting the basic fuel amount.

[0053] The fuel amount correction unit 313 receives the basic fuel amount calculated by the basic fuel amount calculation unit 308, the water temperature sensor signal output by the water temperature sensor 117, the fuel ratio feedback correction coefficient calculated by the air-fuel ratio feedback correction coefficient calculation unit 311, and fuel properties (described later). The fuel amount correction unit 313 corrects the basic fuel amount based on the engine water temperature, the air-fuel ratio feedback correction coefficient, and the fuel properties.

[0054] The fuel amount corrected by the fuel amount correction unit 313 is input to the fuel injection valve drive unit 314. The fuel injection valve drive unit 314 controls the drive of the fuel injection device 119 to cause the fuel injection device 119 to inject the corrected amount of fuel.

[0055] The water temperature sensor signal output by the water temperature sensor 117, the basic ignition timing calculated by the basic ignition timing calculation unit 309, and fuel properties (described later) are input to the ignition timing correction unit 315. The ignition timing correction unit 315 corrects the basic ignition timing based on the water temperature sensor signal and the fuel properties.

[0056] The ignition timing corrected by the ignition timing correction unit 315 is input to the ignition module drive 316. The ignition module drive 316 controls the drive of the ignition module and causes the ignition module to discharge at the corrected ignition timing. As a result, the fuel mixture supplied to each cylinder is ignited.

[0057] As shown in FIG. 5, the ECU 118 includes a fuel temperature calculation unit 320, a refueling determination calculation unit 321, and a fuel property determination unit 322.

[0058] An intake air temperature sensor signal output by the intake air temperature sensor is input to fuel temperature calculation unit 320. Based on the intake air temperature sensor signal, fuel temperature calculation unit 320 calculates the temperature of fuel in common rail 112. The intake air temperature sensor and fuel temperature calculation unit 320 correspond to the fuel temperature detection unit according to the present invention.

[0059] The temperature of the fuel in the common rail 112 may be obtained from an output signal of a temperature sensor provided in the common rail 112. In this case, the temperature sensor corresponds to the fuel temperature detection unit according to the present invention.

[0060] A fuel gauge is installed in fuel tank 109. A fuel gauge signal output by the fuel gauge is input to refueling determination calculation unit 321. Based on the fuel gauge signal, refueling determination calculation unit 321 determines whether fuel has been refueled in fuel tank 109.

[0061] The fuel property determination unit 322 receives as input the fuel temperature calculated by the fuel temperature calculation unit 320 and the determination result of the refueling determination calculation unit 321. Furthermore, the fuel property determination unit 322 receives as input the fuel pressure sensor signal output by the fuel pressure sensor 113, the target fuel pressure value calculated by the target fuel pressure calculation unit 305, and a solenoid control signal output by the high-pressure fuel pump drive unit 307 to the high-pressure fuel pump 111. The solenoid control signal is a signal that controls the drive of the high-pressure fuel pump 111.

[0062] The fuel property determination unit 322 calculates the balance between the amount of fuel supplied and the amount of fuel reduced in the common rail 112 (hereinafter referred to as "fuel balance") based on at least the target fuel pressure, the fuel pressure sensor signal, and the fuel temperature. The fuel balance is correlated with the viscosity of the fuel. The fuel property can be estimated from the viscosity of the fuel. Therefore, the fuel property determination unit 322 estimates the fuel property based on the fuel balance. The fuel property determination unit 322 corresponds to the fuel balance calculation unit and the property estimation unit according to the present invention.

[0063] The fuel property determination unit 322 sends the estimated fuel property to a target fuel pressure calculation unit 305, a fuel pressure feedback correction coefficient calculation unit 306, a basic fuel amount calculation unit 308, a basic ignition timing calculation unit 309, an air-fuel ratio feedback correction coefficient calculation unit 311, and a target air-fuel ratio calculation unit 312. The fuel property determination unit 322 also sends the estimated fuel property to a fuel amount correction unit 313 and an ignition timing correction unit 315. These various calculation units and correction units correspond to the parameter setting unit according to the present invention.

[0064] [Fuel pump drive timing] Next, the drive timing of the high-pressure fuel pump 111 will be described with reference to FIG. FIG. 6 is a diagram showing the drive timing of the high-pressure fuel pump 111.

[0065] 6 represents the locus of the up-and-down reciprocating motion of the plunger 2 when a pump drive cam (not shown) of the internal combustion engine 100 rotates. The pump drive cam rotates in conjunction with the rotation of the intake cam.

[0066] The period when the cam lift is increasing is the compression stroke in which the plunger 2 rises and pressurizes the fuel. Therefore, the period when the cam lift is increasing is the period when the high-pressure fuel pump 111 is able to discharge fuel. Therefore, the high-pressure fuel pump driving unit 307 drives the electromagnetic intake valve mechanism 3 during the period when the cam lift is increasing, causing the high-pressure fuel pump 111 to discharge fuel.

[0067] The electromagnetic intake valve mechanism 3 is driven by switching the solenoid control signal from low to high to energize the solenoid of the electromagnetic intake valve mechanism 3. When the electromagnetic intake valve mechanism 3 is driven, the intake valve 32 opens and fuel flows into the pressurizing chamber 11.

[0068] If fuel starts to flow into the pressurizing chamber 11 immediately after the cam lift starts to increase, the amount of fuel discharged from the high-pressure fuel pump 111 increases. On the other hand, if fuel starts to flow into the pressurizing chamber 11 around the time when the cam lift finishes increasing, the amount of fuel discharged from the high-pressure fuel pump 111 decreases.

[0069] High-pressure fuel pump drive unit 307 specifies the drive timing of high-pressure fuel pump 111 as a period of time that has elapsed since the rotational position of the pump drive cam is at a reference angle. In this way, high-pressure fuel pump drive unit 307 controls the amount of fuel discharged from high-pressure fuel pump 111 (fuel discharge amount).

[0070] That is, the high-pressure fuel pump drive unit 307 increases the fuel discharge amount of the high-pressure fuel pump 111 by setting the source solenoid control signal to High at an early timing during the period in which the cam lift is increasing. On the other hand, the high-pressure fuel pump drive unit 307 decreases the fuel discharge amount of the high-pressure fuel pump 111 by setting the source solenoid control signal to High at a later timing during the period in which the cam lift is increasing.

[0071] High-pressure fuel pump drive unit 307 feedback-controls the drive timing of high-pressure fuel pump 111 while monitoring the target fuel pressure and the actual fuel pressure. For example, if the target fuel pressure increases, the difference between the target fuel pressure and the actual fuel pressure increases, and therefore it is necessary to increase the fuel discharge amount of high-pressure fuel pump 111. Therefore, high-pressure fuel pump drive unit 307 advances the drive timing to increase the fuel discharge amount of high-pressure fuel pump 111. This causes the actual fuel pressure to approach or match the target fuel pressure. For example, when the target fuel pressure does not change, high-pressure fuel pump drive unit 307 controls the drive timing of high-pressure fuel pump 111 so that the fuel discharge amount of high-pressure fuel pump 111 is equal to the amount of fuel injected from fuel injector 119.

[0072] [Fuel pump drive timing and fuel viscosity] Next, the driving timings of high-pressure fuel pump 111 and the change in actual fuel pressure during the process of replacing the remaining fuel with new fuel will be described with reference to FIG. FIG. 7 is a diagram showing the relationship between the drive timing of the high-pressure fuel pump 111 and the fuel viscosity.

[0073] 7 shows a case where the viscosity of the fuel supplied is higher than that of the fuel remaining in fuel tank 109 before refueling. The balance between the amount of fuel supplied from high-pressure fuel pump 111 to common rail 112 and the amount of fuel reduced that flows out of common rail 112 via fuel injection device 119 varies depending on the fuel viscosity. For example, as the fuel viscosity gradually increases, the amount of fuel reduced gradually increases relative to the amount of fuel supplied. As a result, the actual fuel pressure decreases relative to the target fuel pressure over time.

[0074] Therefore, in this embodiment, the fuel property determination unit 322 (see FIG. 5) of the ECU 118 calculates the fuel balance from the change in the actual fuel pressure during each pressurization control and injection control for each combustion cycle of the internal combustion engine 100. This allows the fuel property determination unit 322 to easily calculate the fuel balance.

[0075] Next, the fuel property determination unit 322 estimates the fuel property based on the calculated fuel balance and the fuel temperature calculated by the fuel temperature calculation unit 320. This allows the fuel property determination unit 322 to estimate the fuel property during a transition period when a different type of fuel is being replaced. Note that fuel viscosity is highly dependent on fuel temperature. Therefore, the fuel property determination unit 322 estimates the fuel property taking the fuel temperature into consideration.

[0076] The fuel property determination unit 322 sends the estimated fuel properties to various calculation units and various correction units. The various calculation units and various correction units set control parameters for the internal combustion engine 100 based on the estimated fuel properties. As a result, the ECU 118 can appropriately control the internal combustion engine 100 even during a transition period when a different type of fuel is being used.

[0077] The various calculation units include a target fuel pressure calculation unit 305, a fuel pressure feedback correction coefficient calculation unit 306, a basic fuel amount calculation unit 308, a basic ignition timing calculation unit 309, an air-fuel ratio feedback correction coefficient calculation unit 311, and a target air-fuel ratio calculation unit 312. The various correction units include a fuel amount correction unit 313 and an ignition timing correction unit 315.

[0078] Furthermore, as the fuel viscosity gradually increases, the drive timing of high-pressure fuel pump 111 gradually changes. Specifically, as the actual fuel pressure becomes lower than the target fuel pressure, the drive timing of high-pressure fuel pump 111 gradually advances in order to make the actual fuel pressure coincide with the target fuel pressure. Also, the duty ratio of the drive pulse in the solenoid control signal gradually increases.

[0079] Therefore, the fuel property determining unit 322 may calculate the fuel balance from the change in the drive pulse. That is, the fuel property determining unit 322 may calculate the fuel balance by detecting the change in the drive timing and duty ratio of the drive pulse during each pressurization control and injection control period for each combustion cycle of the internal combustion engine 100. This allows the fuel property determining unit 322 to easily calculate the fuel balance.

[0080] Even in this case, the fuel property determination unit 322 estimates the fuel property based on the calculated fuel balance and the fuel temperature calculated by the fuel temperature calculation unit 320. As a result, the fuel property determination unit 322 can estimate the fuel property during a transitional period when a different type of fuel is being used. Thus, the ECU 118 can appropriately control the internal combustion engine 100 even during a transitional period when a different type of fuel is being used.

[0081] The fuel property determining unit 322 may calculate the fuel balance based on the change in the actual fuel pressure and the change in the drive pulse, thereby improving the accuracy of the calculation of the fuel balance.

[0082] Fuel viscosity is highly dependent on fuel temperature. Therefore, the fuel property determination unit 322 may store in advance in a storage unit how the drive timing changes due to an increase or decrease in fuel temperature, and estimate the property of the supplied fuel from the difference in how the drive timing changes under the same temperature change conditions.

[0083] That is, the fuel property determination unit 322 may estimate the fuel property using the relationship between the change in the drive timing of the drive pulse and the temperature change of the fuel. This allows the influence of temperature change to be eliminated when estimating the property of the fuel that has been refueled. As a result, the ECU 118 can quickly switch to control the newly refueled fuel, thereby maintaining efficient operation of the internal combustion engine 100.

[0084] 2. Second embodiment An internal combustion engine according to a second embodiment of the present invention will be described below. Note that common members are denoted by the same reference numerals in the various drawings.

[0085] [Internal combustion engine] First, an example of the configuration of a plug-in hybrid vehicle equipped with an internal combustion engine according to the second embodiment will be described with reference to FIG. FIG. 8 is a schematic diagram showing the configuration of a plug-in hybrid vehicle according to the second embodiment.

[0086] 8, plug-in hybrid vehicle 400 includes a high-voltage battery 401, an inverter 402, a motor / generator 403, an engine (internal combustion engine) 404, a low-voltage battery 405, and a starter 406. Plug-in hybrid vehicle 400 also includes a battery controller 407, a motor controller 408, an engine controller 409, a hybrid controller 410, and a charger 413.

[0087] The engine 404 has the same configuration as the internal combustion engine 100 of the first embodiment. The charger 413 charges the high-voltage battery 401 from a power source external to the vehicle. The charger 413 is connected to the external power source when the vehicle is stopped, and charges the high-voltage battery 401 according to a specified charging profile. The charger 413 monitors the voltage and current of the high-voltage battery 401 during charging, and maintains an appropriate charging state.

[0088] The motor / generator 403 is a synchronous motor / generator with a permanent magnet embedded in the rotor and a stator coil wound around the stator. A three-phase AC generated by the inverter 402 is applied to the motor / generator 403. The motor / generator 403 operates based on a control command from a motor controller 408.

[0089] The motor / generator 403 functions as an electric motor that receives power from the high-voltage battery 401 to rotate and drive it. The motor / generator 403 also functions as a generator that receives rotational energy from the engine 404 or drive wheels to generate electromotive force. The power generated by the motor / generator 403 can be charged into the high-voltage battery 401.

[0090] Low-voltage battery 405 supplies power to auxiliary equipment such as a radiator mounted on the vehicle. Low-voltage battery 405 also supplies power to starter 406. Pinion gear 411 is connected to starter 406. Pinion gear 411 has a relay that is different from the drive relay for energizing starter 406. When this relay is energized, pinion gear 411 is pushed out and connected to ring gear 412 of engine 404.

[0091] Starter 406 rotates when power is supplied from low-voltage battery 405. When starter 406 rotates, pinion gear 411 rotates. The rotation of pinion gear 411 is transmitted to ring gear 412. As a result, engine 404 starts.

[0092] The engine controller 409 controls the start and stop of the engine 404. The engine controller 409 controls the amount of fuel supplied to the engine 404 and the ignition timing based on the operating conditions. The engine controller 409 corresponds to the internal combustion engine control device according to the present invention.

[0093] The plug-in hybrid vehicle 400 has an electric vehicle driving mode (EV mode) and a hybrid vehicle driving mode (HEV mode). A hybrid controller 410 controls switching between the EV mode and the HEV mode. The hybrid controller 410 controls the distribution of energy obtained from the engine 404 and the motor / generator 403 to obtain optimal fuel economy and performance.

[0094] The HEV mode is a mode in which the vehicle runs using the engine 404 and the motor / generator 403 as drive sources. The HEV mode has a motor-assisted running mode, a power generation running mode, and an engine running mode. In the EV mode, the plug-in hybrid vehicle 400 runs in one of the motor-assisted running mode, the power generation running mode, and the engine running mode.

[0095] In plug-in hybrid vehicle 400, priority is given to using the power of high-voltage battery 401. Therefore, hybrid controller 410 selects EV driving mode when the SOC (State Of Charge) of high-voltage battery 401 is high. On the other hand, when the SOC of high-voltage battery 401 drops, hybrid controller 410 selects HEV mode and starts engine 404.

[0096] The battery controller 407 controls the charging and discharging of the high-voltage battery 401. The battery controller 407 monitors the SOC of the high-voltage battery 401, and charges the high-voltage battery 401 with power generated by the motor / generator 403 as needed. Furthermore, when the motor / generator 403 requires power from the high-voltage battery 401, the battery controller 407 controls the high-voltage battery 401 to supply power from the high-voltage battery 401 to the motor / generator 403.

[0097] [Engine controller functional configuration] Next, the functional configuration of the engine controller 409 will be described with reference to FIG. FIG. 9 is a block diagram showing the functional configuration of the engine controller 409.

[0098] The functional configuration of the engine controller 409 is equivalent to the functional configuration of the ECU 118 according to the first embodiment. The engine controller 409 differs from the ECU 118 according to the first embodiment in that it includes an agitation control unit 323.

[0099] 9, the determination result of the refueling determination calculation unit 321 is input to the stirring control unit 323. When the refueling determination calculation unit 321 determines that fuel has been refueled in the fuel tank 109, the stirring control unit 323 sends an EV mode switching signal to the hybrid controller 410. Upon receiving the EV mode switching signal, the hybrid controller 410 selects the EV mode. As a result, the plug-in hybrid vehicle 400 runs in EV mode after refueling.

[0100] When the EV mode is selected, the agitation control unit 323 sends a drive command signal to the feed pump 110. This causes the feed pump to operate and agitate the fuel in the fuel tank. The feed pump stops operating after a predetermined period of time has elapsed. When the operation of the feed pump has finished, the agitation control unit 323 determines that the agitation of the fuel has been completed.

[0101] When fuel mixing is complete, the mixing control unit 323 sends an HEV mode switching signal to the hybrid controller 410. Upon receiving the HEV mode switching signal, the hybrid controller 410 selects the HEV mode. In addition, the mixing control unit 323 sends a mixing completion signal to the fuel property determination unit 322. Upon receiving the mixing completion signal, the fuel property determination unit 322 calculates the fuel balance and estimates the fuel property as described in the first embodiment.

[0102] In this way, the plug-in hybrid vehicle 400 of the second embodiment has a period during which the engine 404 is not operated in EV mode after refueling is completed and before the engine 404 is next operated in HEV mode. During the period during which the engine 404 is not operated, the mixing control unit 323 operates the feed pump 110 to mix the fuel in the fuel tank. This promotes mixing of the fuel remaining in the fuel tank before refueling with the newly supplied fuel. As a result, it is possible to reduce the difference between the fuel properties used to control the engine 404 after refueling and the fuel properties of the fuel actually supplied from the fuel tank to the combustion chamber.

[0103] [Fuel property determination process] Next, an example of the fuel property determination process performed by the fuel property determination unit 322 of the engine controller 409 will be described with reference to FIG. FIG. 10 is a flowchart showing an example of a fuel property determination process according to the second embodiment.

[0104] The fuel property determination unit 322 executes a fuel property determination process during the HEV mode. First, the fuel property determination unit 322 adds "1" to the boost mode counter (S1). The boost mode counter counts the number of times the pump boost mode has been executed.

[0105] Next, the fuel property determination unit 322 executes the pressure increase mode (S2). The pressure increase mode is a mode in which the actual fuel pressure continues to increase over multiple cycles. In the pressure increase mode, the engine controller 409 controls the drive of the high-pressure fuel pump 111 and the fuel injector 119 so that the target fuel pressure becomes higher than the actual fuel pressure. The fuel property determination unit 322 corresponds to the mode control unit according to the present invention.

[0106] Next, the fuel property determination unit 322 records the change in the drive pulse in the recording unit (S3). The fuel property determination unit 322 also records the change in the actual fuel pressure in the recording unit (S4). The fuel property determination unit 322 also records the change in the fuel temperature in the recording unit (S5).

[0107] Next, the fuel property determination unit 322 determines whether the value of the pressure boost mode counter is 2 or greater (S6). In this embodiment, the threshold value of the pressure boost mode counter is set to 2, but the threshold value of the pressure boost mode counter according to the present invention can be set to any number as long as it is 2 or greater. In other words, the pump pressure boost mode needs to be executed at least twice.

[0108] If it is determined in step S6 that the value of the pressure increase mode counter is not equal to or greater than 2 (NO in step S6), the fuel property determination unit 322 executes the pressure reduction mode (S7). The pressure reduction mode is a mode in which the actual fuel pressure continues to decrease over multiple cycles. In the pressure reduction mode, the engine controller 409 controls the operation of the high-pressure fuel pump 111 and the fuel injector 119 so that the target fuel pressure is lower than the actual fuel pressure. After processing step S7, the fuel property determination unit 322 returns to the processing of step S1.

[0109] In step S6, if it is determined that the value of the boost mode counter is 2 or more (YES in step S6), the fuel property determination unit 322 estimates the fuel property (S8). After processing in step S8, the fuel property determination unit 322 ends the fuel property determination process.

[0110] [Relationship between target fuel pressure, actual fuel pressure and fuel viscosity] Next, the relationship between the target fuel pressure and actual fuel pressure of high-pressure fuel pump 111 and the fuel viscosity will be described with reference to FIG. FIG. 11 is a diagram showing the relationship between the target fuel pressure and actual fuel pressure of high-pressure fuel pump 111 and the fuel viscosity.

[0111] In this embodiment, an example will be described in which the viscosity of the fuel being refueled is higher than the viscosity of the fuel remaining in the fuel tank before refueling. Figure 11 shows the change in actual fuel pressure due to repeated switching between the pressure increase mode and the pressure decrease mode, and the change in fuel viscosity in the fuel pump due to fuel replacement.

[0112] As shown in FIG. 11, the viscosity of the fuel in high-pressure fuel pump 111 gradually increases as new fuel flows in. This causes the amount of fuel supplied by high-pressure fuel pump 111 to decrease even with the same pressure. As a result, as the fuel viscosity gradually increases, the time required for the actual fuel pressure to reach the target fuel pressure increases. When the boost mode is executed multiple times, changes in the actual fuel pressure due to the increase in fuel viscosity appear. Therefore, the amount of fuel increase (fuel balance) can be calculated from the change in the actual fuel pressure.

[0113] The fuel property determination unit 322 calculates the fuel increase amount from the change in the actual fuel pressure (fuel pressure) detected by the fuel pressure sensor 113. This allows the fuel property determination unit 322 to easily calculate the fuel balance. The fuel property determination unit 322 estimates the fuel property according to the calculated increase amount. This allows the fuel property determination unit 322 to determine the fuel property during a transition period when a different type of fuel is being replaced.

[0114] The fuel property determination unit 322 sends the estimated fuel properties to various calculation units and correction units. The calculation units and correction units set control parameters for the engine 404 based on the estimated fuel properties. As a result, the engine controller 409 can appropriately control the engine 404 even during a transition period when a different type of fuel is being used.

[0115] In this embodiment, fuel injection by the fuel injector 119 is not prohibited during the period in which the boost mode is being executed. However, during the period in which the boost mode is being executed, the engine controller 409 may prohibit fuel injection by the fuel injector 119. This reduces disturbances included in the change in fuel pressure, and can improve the accuracy of estimating the fuel properties.

[0116] Note that prohibiting fuel injection reduces torque, so the torque reduction is compensated for by the electric motor. This makes it possible to estimate fuel properties without impairing drivability.

[0117] The embodiments of the internal combustion engine control device and the internal combustion engine control method of the present invention have been described above, including their effects. However, the internal combustion engine control device and the internal combustion engine control method of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention as defined in the claims.

[0118] The fuel property determination unit 322 of the first embodiment described above also functions as the fuel balance calculation unit and the property estimation unit according to the present invention. However, the fuel balance calculation unit and the property estimation unit according to the present invention may be provided as separate functional components. Furthermore, the fuel property determination unit 322 of the first embodiment described above also functions as the fuel balance calculation unit, the property estimation unit, and the mode control unit according to the present invention. However, the fuel balance calculation unit, the property estimation unit, and the mode control unit according to the present invention may be provided as separate functional components.

[0119] Furthermore, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the configurations described. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0120] 100...internal combustion engine, 101...cylinder head, 102...cylinder block, 103...piston, 104...combustion chamber, 105...intake pipe, 106...exhaust pipe, 107...intake valve, 108...exhaust valve, 109...fuel tank, 110...feed pump, 111...high-pressure fuel pump, 112...common rail, 113...fuel pressure sensor, 114...connecting rod, 115...crankshaft, 116...crank angle sensor, 117...water temperature sensor, 118...ECU (internal combustion engine control unit), 119...fuel injection device, 120...low-pressure piping, 131...crankshaft, 301...driving operation detection unit, 302...engine rotation speed calculation unit, 303...cylinder inflow air amount calculation unit, 304...target throttle opening calculation unit, 305...Target fuel pressure calculation unit, 306...Fuel pressure feedback correction coefficient calculation unit, 307...High pressure fuel pump drive unit, 308...Basic fuel amount calculation unit, 309...Basic ignition timing calculation unit, 310...ISC control unit, 311...Air-fuel ratio feedback correction coefficient calculation unit, 312...Target air-fuel ratio calculation unit, 313...Fuel amount correction unit, 314...Fuel injection valve drive unit, 315...Ignition timing correction unit, 316...Ignition module drive, 320...Fuel temperature calculation unit, 321...Fuel supply determination calculation unit, 322...Fuel property determination unit, 323...Agitation control unit, 400...Plug-in hybrid vehicle, 401...High voltage battery, 402...Inverter, 403...Motor / generator, 404...Engine, 405...Low voltage battery, 406...Starter, 407...Battery controller, 408...Motor controller, 409...Engine controller (internal combustion engine control device), 410...Hybrid controller, 411...Pinion gear, 412...Ring gear, 413...Charger

Claims

1. 1. An internal combustion engine control device for controlling an internal combustion engine including a fuel pump that supplies fuel to a common rail and a fuel injection device that injects fuel in the common rail into a combustion chamber, a fuel balance calculation unit that calculates a fuel balance, which is a difference between the amount of fuel supplied by the fuel pump and the amount of fuel reduced by injection by the fuel injection device; a property estimation unit that estimates a fuel property according to the fuel balance; a parameter setting unit that sets control parameters for controlling the internal combustion engine based on the fuel properties. Internal combustion engine control device.

2. the internal combustion engine includes a fuel pressure detection unit that detects the fuel pressure in the common rail, and a fuel temperature detection unit that detects the fuel temperature in the common rail; The fuel balance calculation unit calculates the fuel balance based on a change in fuel pressure detected by the fuel pressure detection unit during a period of fuel supply control by the fuel pump and a period of injection control by the fuel injection device for each combustion cycle of the internal combustion engine, and based on the fuel temperature detected by the fuel temperature detection unit. The internal combustion engine control device according to claim 1.

3. the internal combustion engine includes a fuel temperature detection unit that detects the temperature of fuel in the common rail, The fuel balance calculation unit calculates the fuel balance based on a change in a drive signal of the fuel pump during a period of fuel supply control by the fuel pump and a period of injection control by the fuel injection device for each combustion cycle of the internal combustion engine, and based on the fuel temperature detected by the fuel temperature detection unit. The internal combustion engine control device according to claim 1.

4. The property estimation unit estimates the fuel property based on the fuel balance and the fuel temperature detected by the fuel temperature detection unit.

4. The internal combustion engine control device according to claim 2 or 3.

5. the internal combustion engine includes a fuel tank that accommodates fuel to be supplied to the fuel pump, and a feed pump that sends fuel in the fuel tank to the fuel pump, a feed pump control unit that drives the feed pump to agitate the fuel in the fuel tank during the period from when refueling of the fuel tank is completed until the property estimation unit estimates the fuel property; The internal combustion engine control device according to claim 1.

6. the internal combustion engine includes a fuel pressure detection unit that detects the fuel pressure of the common rail, a mode control unit that controls a pressure increase mode for increasing the pressure of fuel in the common rail and a pressure decrease mode for decreasing the pressure of fuel in the common rail, the mode control unit executes the pressure reduction mode after executing the pressure increase mode, and then executes the pressure increase mode again; The fuel balance calculation unit calculates the fuel balance based on a difference in fuel pressure detected by the fuel pressure detection unit during each of the boost mode periods. The internal combustion engine control device according to claim 1.

7. 1. A method for controlling an internal combustion engine including a fuel pump that supplies fuel to a common rail and a fuel injection device that injects fuel from the common rail into a combustion chamber, the method comprising: a fuel balance calculation unit calculates a fuel balance which is a difference between the amount of fuel supplied by the fuel pump and the amount of fuel reduced by injection by the fuel injection device; a property estimation unit that estimates the fuel property according to the fuel balance; A parameter setting unit sets control parameters for controlling the internal combustion engine based on the fuel properties. Internal combustion engine control method.

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