JP3988541B2 - Accumulated fuel injection system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure accumulation fuel injection device, and more particularly to a common rail fuel injection device that accumulates high pressure fuel discharged from a high pressure pump in a common rail and injects the accumulated high pressure fuel to an internal combustion engine via a fuel injection valve. The present invention relates to the improvement of startability of an internal combustion engine related to
[0002]
[Prior art]
As a pressure accumulation type fuel injection device, for example, in a common rail type fuel injection device as a fuel injection system for a diesel engine, a high pressure pump that is driven by the rotational force of the crankshaft of the diesel engine and discharges the fuel pumped from the fuel tank at a high pressure And a high-pressure fuel discharged from the high-pressure pump is known that includes a common rail that functions as a kind of surge tank.
[0003]
In this type of accumulator fuel injection device, an adjustment solenoid valve attached to a high-pressure pump is controlled based on a control signal from an ECU as a control device, and is pumped from a high-pressure pump to a common rail via a fuel pipe. Adjust the pumping amount of high-pressure fuel. Thereby, the common rail pressure is changed to a desired injection pressure.
[0004]
[Problems to be solved by the invention]
In the conventional configuration, the discharge amount of the high-pressure pump varies due to individual differences among the adjusting solenoid valves. In particular, at the time of starting, variation in the injection amount and injection pressure from the fuel injection valve to the diesel engine, that is, the internal combustion engine is caused by the individual difference of the adjusting solenoid valve, that is, the individual difference of the high-pressure pump. There is a problem that it contributes to variations in starting performance.
[0005]
The present invention has been made in consideration of such circumstances, and therefore the object thereof is a pressure accumulation type fuel injection device capable of ensuring a predetermined startability of an internal combustion engine regardless of variations among individual high-pressure pumps. Is to provide.
[0006]
[Means for Solving the Problems]
According to claim 1 of the present invention, a high-pressure pump that pumps fuel from a fuel tank, a common rail that accumulates high-pressure fuel discharged from the high-pressure pump, and a high-pressure that is provided for each cylinder of the internal combustion engine and accumulated in the common rail A plurality of fuel injection valves for supplying fuel to the combustion chamber of the cylinder, an operating state detecting means for detecting the operating state of the internal combustion engine, and a fuel pressure detecting means for detecting the fuel pressure of the high-pressure fuel accumulated in the common rail And a discharge amount control means for controlling the discharge amount of the high-pressure pump in accordance with the operation state detected by the operation state detection means and the fuel pressure detected by the fuel pressure detection means. When starting the internal combustion engine, the operating state detection means detects the time required to reach the predetermined internal combustion engine speed, and the fuel pressure detection means detects the fuel pressure boosting characteristic. , The arrival time when exceeding a predetermined start-up time, increases or decreases the discharge rate of the next startup in accordance with the pressure rise characteristics.
[0007]
When the internal combustion engine is started, for example, an arrival time until reaching a predetermined number of revolutions such as idle rotation and a pressure increase characteristic of the fuel pressure in the common rail are detected, and this arrival time exceeds a desired predetermined start time. Since the discharge amount at the next start is increased or decreased based on the above boosting characteristics, a predetermined startability can be ensured regardless of individual differences of the high pressure pumps.
[0008]
According to claim 2 of the present invention, the high-pressure pump includes a flow rate control valve that adjusts the amount of fuel drawn from the fuel tank, and the discharge amount control means changes the drive amount output to the flow rate control valve.
[0009]
As a result, the individual difference of the flow control valve that adjusts the fuel intake amount, which is the cause of the individual difference of the high-pressure pump, can be offset by adjusting the drive amount of the flow control valve output from the discharge amount control means. it can.
[0010]
According to claim 3 of the present invention, the flow control valve is a linear solenoid. When starting the linear solenoid with a predetermined drive amount so that the opening area of the flow control valve is in a predetermined half-open state between the fully open state and the fully closed state, for example, at the next start based on the above drive time Since the predetermined drive amount is increased or decreased, learning control for ensuring a predetermined startability can be easily performed.
[0011]
The drive amount output to the flow rate control valve is performed by duty control as described in claim 4 of the present invention.
[0012]
Thus, by changing the duty ratio, for example, the ratio of the opening / closing period, that is, the ratio between the valve opening period and the valve closing period can be controlled, so that the fuel intake amount can be adjusted according to the valve opening period, and thus the desired startability can be achieved. It can be secured. Note that the opening area of the flow control valve may be controlled to a predetermined opening area by changing the duty ratio.
[0013]
According to claim 5 of the present invention, Boost The characteristic is an increase amount of the fuel pressure per unit time, and the discharge amount control means has a predetermined upper limit increase value and a predetermined lower limit increase value, and when the boosting characteristic is not less than the predetermined upper limit increase value, the drive amount Increase By correcting so that the discharge amount is reduced at the next start When the boosting characteristic is below the predetermined lower limit increase value, the drive amount is decreased. The discharge amount at the next start is increased by correcting to .
[0014]
Thus, a predetermined upper limit increase value and a predetermined lower limit increase value are set as boosting characteristics that can ensure a predetermined startability based on experiments or the like, and the driving amount is compared with the predetermined upper limit increase value and the predetermined lower limit increase value. By changing the above, the learning control can be performed continuously at each starting time until the predetermined starting time or less is reached, that is, until a predetermined starting property is ensured.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in which the pressure-accumulated fuel injection device of the present invention is applied to a common rail fuel injection device mounted on a diesel engine will be described with reference to the drawings.
[0030]
(First embodiment)
(Schematic configuration of this embodiment applied to a common rail fuel injection device)
FIG. 1 is a configuration diagram illustrating a system schematic configuration of a common rail fuel injection device to which an accumulator fuel injection device according to an embodiment of the present invention is applied. FIG. 2 is a schematic configuration diagram showing the control system in FIG.
[0031]
As shown in FIG. 1, the common rail fuel injection device includes a high pressure pump 7 that pumps fuel from a fuel tank 6, a common rail 5 that is a type of surge tank that accumulates high pressure fuel discharged from the high pressure pump 7, and a multi-cylinder. (4 cylinders in FIG. 1) A fuel injection valve (hereinafter referred to as an injector) that is provided for each cylinder of a diesel engine (hereinafter referred to as an engine) and that injects high-pressure fuel accumulated in a common rail 5 into a combustion chamber of the cylinder. 1) to 4), an operating state detecting means 70 for detecting the operating state of the engine, a fuel pressure detecting means 81 for detecting the fuel pressure of the high pressure fuel accumulated in the common rail 5, and an operating state detecting means 70. A discharge amount control means 10 for controlling the discharge amount of the high-pressure pump according to the operated state and the fuel pressure detected by the fuel pressure detection means 81. That. The control means 10 is a control device that controls the engine, and is not limited to the control of the high-pressure pump 7, but is an electronic control unit (hereinafter referred to as ECU) that electronically controls a plurality of injectors 1 to 4. is there.
[0032]
Here, the engine flywheel (not shown) is rotated at a speed higher than the minimum rotational speed necessary for starting the engine by a starter (engine starting motor) (not shown) that is rotated by battery power. Start with. The starter is energized by the ECU 10 when the vehicle occupant turns the ignition switch from the OFF position to the ST position (the starter ON signal is turned ON).
[0033]
A plurality (four in this embodiment) of injectors 1 to 4 are attached to the combustion chambers of the cylinders of the engine and inject and supply high-pressure fuel into the combustion chambers of the engine. The fuel injection amount and fuel injection timing from the injectors 1 to 4 to the engine are electronically controlled by the ECU 10 to energize and deenergize the injection period control solenoid valves (injection period varying means) 11 to 14 as actuators. To be determined.
[0034]
The common rail 5 is a kind of surge tank that stores high-pressure fuel having a relatively high pressure (in the range of 100 to 1000 times the atmospheric pressure) (hereinafter referred to as common rail pressure), and each injector 1 is connected via a high-pressure pipe 8. Connected to ~ 4. The fuel return pipes 9 from the injectors 1 to 4, the common rail 5, and the high pressure pump 7 to the fuel tank 6 are also connected from the pressure limiter 15 so that the common rail pressure in the common rail 5 does not exceed the limit accumulated pressure. It is configured to release pressure.
[0035]
The high-pressure pump 7 rotates with the rotation of the crankshaft (not shown) of the engine, thereby pumping up the fuel in the fuel tank 6 through the fuel pipe 17 with the fuel filter 16 interposed (not shown). And a supply pump that pressurizes fuel sucked out by the feed pump and pumps high-pressure fuel. The high-pressure pump 7 is provided with a flow control electromagnetic valve 19 as a discharge amount adjusting electromagnetic valve.
[0036]
The flow rate control solenoid valve (hereinafter referred to as an injection pressure control solenoid valve) 19 is electronically controlled by a control signal from the ECU 10, thereby pumping high pressure fuel from the high pressure pump 7 to the common rail 5 via the fuel pipe 18. It is an injection pressure variable means for changing the injection pressure at which fuel is injected from the injectors 1 to 4 into the combustion chamber of the engine by adjusting the amount.
[0037]
The ECU 10 includes a CPU that performs control processing and arithmetic processing, a ROM that stores various control programs and data, a RAM that stores input data, an input circuit, an output circuit, a power supply circuit, and an injector drive circuit (hereinafter referred to as EDU) 20. Etc. are comprised. The ECU 10 controls the injection pressure control solenoid valve 19 of the high-pressure pump 7 and the injection period control solenoid valves 11 to 14 of the injectors 1 to 4 according to the engine operation state detected by the operation state detection means 70 described later. To do.
[0038]
The EDU 20 receives a control signal (for example, a control pulse signal) output from the ECU 10, and opens and closes the fuel according to the fuel injection timing (valve opening timing) and the fuel injection amount (= injection period) calculated by the ECU 10. Thus, the battery voltage of the battery (not shown) is boosted, and the supply (energization) or supply stop (energization stop) to each injection period control electromagnetic valve 11 to 14 of each injector 1 to 4 is controlled.
[0039]
The operating state detecting means 70 for inputting a signal indicating the operating state of the engine to the ECU 10 includes a rotational speed sensor 71 that detects the rotational speed of the engine, and an accelerator opening sensor 72 that detects the amount of depression of the accelerator pedal (accelerator opening). There are an intake air temperature sensor 73 for detecting the temperature of intake air taken in by the engine, a cooling water temperature sensor 75 for detecting the cooling water temperature of the engine, a crank angle sensor 77 for detecting the rotation angle of the engine crankshaft and the engine rotation speed, and the like. .
[0040]
Further, as basic sensors to be input to the ECU 10, a fuel pressure sensor (fuel pressure detecting means) 81 for detecting the fuel pressure (injection pressure, common rail pressure) of the high-pressure fuel accumulated in the common rail 5, and a return pipe 9 There is a fuel temperature sensor (fuel temperature detecting means) 82 for detecting the temperature of the fuel.
[0041]
Here, the ECU 10 determines the fuel injection timings of the injectors 1 to 4 based on signals from the crank angle sensor 77 such as a crankshaft rotation pulse signal and a camshaft rotation pulse signal in the operating state of the steady operation of the engine. (Valve opening timing) and the discharge amount (fuel pumping period) of the high-pressure pump 7, and the electromagnetic pressure for controlling the injection pressure of the high-pressure pump 7 so as to maintain the common rail pressure at the optimum injection pressure (= target pressure). The energization timing to the valve 19 is controlled.
[0042]
Then, a fuel injection amount is calculated from values measured by the rotational speed sensor 71, the accelerator opening sensor 72, the cooling water temperature sensor 75, or the fuel temperature sensor 82. In order to achieve this calculated fuel injection amount, In addition, the engine is operated by driving the injection period control solenoid valves 11 to 14 of the injectors 1 to 4 respectively with the injector energization time command (value) calculated from the fuel pressure in the common rail 5.
[0043]
The ECU 10 detects, for example, the cooling water temperature sensor 25 when the vehicle occupant starts energizing the starter and cranks the crankshaft of the engine at the required minimum rotational speed or more for the purpose of starting the engine. The optimal injection start pressure (starting target rail pressure = target pressure) is calculated according to the engine cooling water temperature (TW) or the compensation amount of the engine cooling water temperature (TW) with the starter ON duration taken into account ( Injection start pressure determining means), until the common rail pressure (actual rail pressure) detected by the fuel pressure sensor 81 rises above its target pressure, injector energization time commands (injector valve opening commands) to the injectors 1 to 4 Configured to prohibit. Note that the injector valve opening command may not be prohibited depending on the target start time for ensuring the desired startability of the engine.
[0044]
The ECU described in the present embodiment is configured to prohibit the injector valve opening command until the common rail pressure (actual rail pressure) increases to a predetermined pressure or higher. Thereby, the time from the start of fuel injection until effective combustion can be performed (complete explosion) can be shortened.
[0045]
Here, in the common rail fuel injection device having the above-described configuration, if the predetermined pressure is maintained after the common rail pressure becomes the target pressure, the start time does not vary due to individual differences of the common rail fuel injection device. However, the starting target pressure is generally set lower than the common rail pressure during steady operation, and during starting, there is a transient state in which the common rail pressure further increases after the common rail pressure becomes the target pressure. Exists. For this reason, the transient characteristic of the common rail pressure during start-up is affected by the individual difference of the common rail fuel injection device, particularly the individual difference of the high-pressure pump 7 that pumps high-pressure fuel, and the actual internal combustion engine with respect to the target start time of the engine. In other words, there is a possibility that the start time varies among the individual common rail fuel injection devices and the target time is not satisfied.
[0046]
On the other hand, there is a means for prohibiting the injector valve opening command until the common rail pressure rises to the common rail pressure at the time of starting operation, but in the first place, the starter wasted time until the engine is completely exploded. The start time for cranking the engine from when the vehicle occupant starts energizing the starter to the complete explosion becomes long, and it becomes difficult to ensure the desired startability. In some cases, the power consumption of the battery increases, and the battery may run out and be unable to start.
[0047]
(The main part of this embodiment and its detailed description)
Therefore, the present embodiment provides a pressure accumulation type fuel injection device that can ensure a predetermined startability of the internal combustion engine regardless of variations among the individual high-pressure pumps 7 by having the following features.
[0048]
High-pressure pump control S600 at start-up for correcting the discharge amount with respect to variations in the transient characteristics of the common rail pressure Pc due to individual differences of the high-pressure pump 7 (see FIG. 6B), that is, variations in the discharge amount of the high-pressure pump 7. , See FIG. 6).
[0049]
The starting high-pressure pump control S600 is performed by the ECU 10 to correct the driving amount for driving the flow rate control valve 19 as a discharge amount adjusting electromagnetic valve of the high-pressure pump 7. Note that the discharge amount for the same drive amount also varies due to individual differences in the flow rate control valve 19 described later. Therefore, the discharge amount correction of the high-pressure pump 7 is not a correction that can be appropriately performed at the first start time, but the next start. This is a correction aimed at optimizing the discharge amount. As a result, the start-up high-pressure pump control S600 is continuously performed at each start-up so that optimization can be achieved, and therefore a predetermined startability can be ensured.
[0050]
Hereinafter, the start-up high-pressure pump control S600 of one embodiment will be described with reference to FIGS. FIG. 5 is a flowchart showing pre-processing of the start-time high-pressure pump control executed by the ECU in FIG. FIG. 6 is a flowchart of start-up high-pressure pump control showing one embodiment of the present invention.
[0051]
First, when starting the engine, the vehicle occupant turns the ignition switch from the OFF position to the ST position, so that the starter motor is rotated by the current from the battery, and at the same time, the pinion gear pushed by the overrunning clutch becomes the engine crank. The flywheel is rotated by meshing with a ring gear on the outer periphery of the flywheel directly connected to the shaft. As a result, the crankshaft rotates, and the piston moves up and down in the cylinder of the engine, so that air is sucked into the cylinder through the intake pipe. On the other hand, the high pressure pump 7 pressurizes the fuel pumped from the fuel tank 6 as the crankshaft of the engine rotates, so that the fuel pressure Pc in the common rail 5 increases.
[0052]
At this time, as shown in FIG. 5, in S501 (S represents a step), when the ignition switch is turned to the ST position, the starter ON signal generated when the movable contact and fixed contact of the starter come into contact with each other. Is determined to be ON (starter energization start detection means). If the starter ON signal is in the OFF state, the process ends. On the other hand, if the starter ON signal is in the ON state, the process proceeds to S600 for starting high-pressure pump control.
[0053]
In the starting operation state in which the starter ON signal is determined to be in the ON state by the starter energization start detecting means, the engine is cranked at a speed higher than the minimum rotational speed (for example, 400 rpm) required for starting by the starter. As the shaft rotates, the high pressure pump 7 is driven and the injection pressure control solenoid valve 19 is energized, whereby the fuel pressure (= rail fuel pressure) Pc in the common rail 5 gradually increases.
[0054]
Next, in the start-time high pressure pump control S600, when the control process from S601 to S607 is performed and the time for the engine to reach a predetermined rotation speed (idle rotation in this embodiment) exceeds the target start time, the next start time The predetermined driving amount of the injection pressure control electromagnetic valve 19 is corrected. Details will be described below with reference to FIG.
[0055]
As shown in FIG. 6, in S601, the drive amount D of the injection pressure control electromagnetic valve 19 of the high pressure pump 7 is set to a predetermined value D1. The predetermined value D1 is an initial set value at the time of initial start-up, that is, a predetermined value at the time of shipment from the factory, and at the subsequent start-up, an initial set value (no correction history) is updated by correction. Values are used. Based on the predetermined drive amount D1, the drive control of the injection pressure control solenoid valve 19 is performed by the ECU 10, and the discharge amount of the high-pressure fuel discharged from the high-pressure pump 7 is adjusted. Then, the fuel pressure (common rail pressure) Pc in the common rail 5 gradually increases according to the discharge amount.
[0056]
For the sake of simplicity of explanation, the control processing after S602 will be described below assuming that the initial setting value is input as the driving amount D as the predetermined value D1.
[0057]
In S602, an arrival time Ts for reaching a predetermined rotation speed (in this embodiment, idle rotation) Ns is detected by the rotation speed sensor 71 as the operation state detection means 70 (see (a) in FIG. 6), and pressure detection is performed. The fuel pressure sensor 81 as a means detects the boosting characteristic of the common rail pressure Pc in the common rail 5 and calculates the fuel pressure increase amount (ΔPc / ΔT) per unit time by the ECU 10. Here, (a) shown in S602 is a schematic diagram showing so-called engine blow-up characteristics at start-up, and the engine blow-off from the starter start-up (for example, when the starter ON signal is turned on). It is a graph showing arrival time Ts until it returns to idle rotation Ns through a rising state. (B) shown in S602 is a schematic diagram showing the boosting characteristic of the common rail pressure Pc at the start. The broken line and two-dot chain line characteristics are expressed by ΔPc / ΔT, respectively, with respect to the solid line boosting characteristic. Comparative example showing a case where ΔPc / ΔT is small when large
Here, variation factors due to individual differences in the injection pressure control solenoid valve 19 for adjusting the discharge amount of the high-pressure fuel pumped to the common rail 5 will be described with reference to FIGS. 3 is a schematic diagram for explaining the flow control valve of the high-pressure pump in FIG. 1. FIG. 3 (a) is a sectional view of the flow control valve, and FIG. 3 (b) is a B direction of FIG. 3 (a). It is an enlarged view which shows the suction port seen from. FIG. 4 is a graph showing drive characteristics of one embodiment of the flow control valve of FIG.
[0058]
As shown in FIG. 3 (a), the injection pressure control solenoid valve 19 of the present embodiment is a well-known flow control valve, and includes a mover 19a, a stator core 19a that constitutes a magnetic circuit together with the mover 19a, And an electromagnetic drive unit having an electromagnetic coil 19c that generates an electromagnetic force when energized, a valve body 19d, a valve member 19e that is slidably accommodated in the valve body 19d, and that can reciprocate in conjunction with the mover, and It comprises a valve portion having a biasing spring 19f that biases the valve member 19e toward the mover side. The solenoid valve 19 is a valve body 19d even if it is a suction port (hereinafter referred to as an ON-OFF solenoid valve) that makes the opening area A of FIG. 3B variable by ON-OFF control. It may be a linear solenoid in which the opening area A of the suction port varies depending on the axial position of the valve member 19e that moves in the axial direction.In the ON-OFF solenoid valve, duty control is performed so that the on-off valve period is variable by the ECU. The opening area A can be made variable. On the other hand, in the linear solenoid, the opening area A can be made variable by changing the average drive current by duty control (see FIG. 4).
[0059]
The injection pressure control solenoid valve 19 described in the present embodiment will be described below as a linear solenoid.
[0060]
As shown in the drive characteristic of the injection pressure control electromagnetic valve 19 in which the horizontal axis in FIG. 4 represents the drive amount D and the vertical axis represents the opening area A of the suction port, the injection pressure control electromagnetic valve 19 opens when the drive amount is increased. The area A decreases, that is, the discharge amount decreases. On the other hand, if the drive amount is reduced, the opening area A of the injection pressure control solenoid valve 19 increases, that is, the discharge amount of the high-pressure pump 7 increases.
[0061]
The fluctuation factors of the discharge amount related to the injection pressure control electromagnetic valve 19 are the influence of the attractive force Fc due to the individual difference of the electromagnetic coil 19c generating the electromagnetic force in the electromagnetic drive unit, and the electromagnetic coil 19 generated in the valve unit. The influence of the spring constant K of the biasing spring that determines the axial position of the valve member by balancing with the suction force according to the electromagnetic force, the influence of the set load Fs, and the mover driven by the suction force There are influential factors that arise in manufacturing within design tolerances such as the influence of the valve closing position H of the valve member to be operated. For this reason, even if the drive amount output from the ECU 10 is the same, the discharge amount of the high-pressure pump 7 varies due to individual differences in the injection pressure control electromagnetic valve 19.
[0062]
On the other hand, in the embodiment of the present invention, correction is performed as follows for a case where a predetermined startability cannot be ensured, that is, a case where the arrival time Ts spent for the start exceeds the target time Ta.
[0063]
In S603, it is determined whether or not the arrival time Ts measured in S602 is equal to or less than a target time (for example, 20 seconds) Ta. If the arrival time Ts is within the target time Ta, the control process ends. Conversely, if the arrival time Ts exceeds the target time Ta, the process proceeds to S604 and correction is performed according to the boosting characteristic of the common rail pressure Pc. Note that S604 and S606, which will be described later, are boosting characteristic determining means for determining the boosting characteristic.
[0064]
In S604, the boost characteristic ΔPc / ΔT calculated in S602 (hereinafter referred to as the actual ΔPc / ΔT value) is a range of the boost characteristic ΔPc / ΔT in which it has been confirmed in advance that a predetermined startability can be ensured based on experiments or the like ( Hereinafter, it is determined whether or not it is larger than a predetermined upper limit increase value on the upper limit side (hereinafter referred to as the upper limit value) in the allowable ΔPc / ΔT range). If the actual ΔPc / ΔT value is equal to or greater than the upper limit value, the drive amount (specifically, the duty ratio by duty control) D is increased (D1 = D1 + ΔD) in S605, and the control process is terminated. Conversely, if the actual ΔPc / ΔT value is smaller than the upper limit value, the process proceeds to S606.
[0065]
In S606, it is determined whether or not the actual ΔPc / ΔT value is smaller than a predetermined lower limit increase value (hereinafter referred to as a lower limit value) on the lower limit side in the allowable ΔPc / ΔT range. If the actual ΔPc / ΔT value is less than or equal to the lower limit value, the drive amount (duty ratio) D is decreased (D1 = D1−ΔD) in S607, and the control process ends. Conversely, if the actual ΔPc / ΔT value is greater than the lower limit value, the control process is terminated.
[0066]
When the actual ΔPc / ΔT value is greater than or equal to the upper limit value (for example, the broken line characteristic in (b) of FIG. 6S602) by comparing and determining the boosting characteristic (actual ΔPc / ΔT value) by S604 and S606 and the upper and lower limit values. Can be reduced (D1 = D1 + ΔD) so that the drive amount D of the injection pressure control solenoid valve 19 for adjusting the discharge amount is increased, thereby reducing the discharge amount at the next start, while the actual ΔPc When the / ΔT value is equal to or lower than the lower limit value (for example, the two-dot chain line characteristic of (b) in FIG. 6S602), the correction is performed so that the driving amount D is reduced. The amount of discharge can be increased.
[0067]
Thus, until the arrival time Ts reaches the target start time Ta or less, that is, until the predetermined startability is secured, the drive amount D correction at the next start, that is, the learning control is performed continuously at each start. be able to. Therefore, it is possible to ensure a predetermined startability of the internal combustion engine regardless of variations among the individual high-pressure pumps 7.
[0068]
(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.
[0069]
In the second embodiment, as shown in FIG. 7, as a standard for performing correction for ensuring a predetermined startability, the number of revolutions reached when a predetermined elapsed time T1 from the start (hereinafter referred to as an actual internal combustion engine) is reached. It is determined whether or not N1 has reached the target internal combustion engine speed Na. FIG. 7 is a flowchart of start-up high-pressure pump control according to this embodiment. The high-pressure pump control at the start shown in FIG. 7 is a control process related to the pressure accumulation type fuel injection device applied to the configuration (FIGS. 1 and 2) described in the first embodiment, and this high-pressure pump control at the start As the pre-processing, as in the first embodiment, a control process (see S501 in FIG. 5) for detecting the start time by the starter energization start detecting means is performed.
[0070]
As shown in FIG. 7, in the start-time high-pressure pump control 700, the control processing of S601 and S702 to S706 is performed.
[0071]
After the drive amount D of the injection pressure control solenoid valve 19 of the high-pressure pump 7 is set to the predetermined value D1 by the control process of S601 (see FIG. 6), in S702, the start of the internal combustion engine detected by the starter energization start detection means is detected. The actual internal combustion engine speed N1 when the predetermined elapsed time T1 is reached is detected (see (a) in FIG. 7). Further, when the predetermined elapsed time T1 is reached by the fuel pressure sensor 81, the reached fuel pressure (hereinafter, actual fuel pressure) Pc1 of the common rail pressure Pc is detected.
[0072]
Here, the starter energization start detecting means constitutes an engine start detecting means for detecting a start command for the internal combustion engine. The starter energization start detection means detects when the starter ON signal is switched from the OFF state to the ON state, that is, the starter driving is started and the start time of the internal combustion engine is detected.
[0073]
In S703, it is determined whether or not the actual internal combustion engine speed N1 detected in S702 exceeds a predetermined internal combustion engine speed (hereinafter, target internal combustion engine speed) Na (for example, 400 rpm). If the actual internal combustion engine speed N1 exceeds the target internal combustion engine speed Na, the control process ends. Conversely, if the actual internal combustion engine speed N1 has not reached the target internal combustion engine speed Na, the routine proceeds to S704.
[0074]
In S704, in order to perform a correction for ensuring a predetermined startability, the actual internal combustion engine speed N1 and the actual fuel pressure Pc1 are used as ECU 10 as actual data indicating the startability of the internal combustion engine at a predetermined elapsed time T1. And the process proceeds to S705.
[0075]
In S705 and S706, the actual internal combustion engine speed N1 and the actual fuel pressure Pc1 are used to refer to the data for correction stored in advance, and the initial value D1 of the drive amount D is set to the high pressure mounted on the internal combustion engine. It is corrected to a predetermined initial value (target drive amount) Da suitable for the pump 7 (D = D1 is replaced with D = Da). In S705, using the actual internal combustion engine speed N1, the actual fuel pressure Pc1, and the like, the target fuel pressure Pca is obtained so as to be the target internal combustion engine speed Na at the next start, and in S706, from the target fuel pressure Pca, The target drive amount Da at the next start is determined.
[0076]
Specifically, in S705, the target fuel pressure Pca corresponding to the actual internal combustion engine speed N1 is obtained from the correlation between the fuel pressure Pc at the time of start-up and the internal combustion engine speed N as shown in the graph in S705. The target fuel pressure Pca can be calculated by any method as long as it is derived from a map or a calculation formula. The map includes a one-dimensional map of the actual internal combustion engine speed N1, a two-dimensional map of the actual internal combustion engine speed N1 and the fuel temperature detected by the fuel temperature sensor 81, the actual internal combustion engine speed N1, the actual fuel pressure Pc1, and the fuel temperature. Any of the three-dimensional maps of FIG. The calculation formula includes a function Pca = f (N1) having the actual engine speed N1 as a variable, a function Pca = f (N1, t) having the actual engine speed N1 and the fuel temperature t as variables, and an actual engine. Any of a function Pca = f (N1, Pc1, t) using the rotational speed N1, the actual fuel pressure Pc1, and the fuel temperature t as variables may be used. Compared with the method of simply obtaining the target fuel pressure Pca from the actual internal combustion engine speed N1, the calculation accuracy of the target fuel pressure Pca considering the influence of the fuel temperature is better, and the fuel temperature and the actual fuel pressure generated at the fuel temperature are obtained. The calculation accuracy of the target fuel pressure Pca considering Pc1 is even better. By calculating the target fuel pressure Pca in consideration of the fuel temperature, it is possible to ensure startability even at a low temperature start. In S706, the target drive amount (target duty ratio) Da corresponding to the target fuel pressure Pca is obtained from the correlation between the fuel pressure Pc and the drive amount (duty ratio) D at the start, as shown in the graph in S706. As a method for calculating the target drive amount Da, a one-dimensional map of the target fuel pressure Pca, a two-dimensional map of the target fuel pressure Pca and the fuel temperature, the target fuel pressure Pca, the fixed drive amount D1 at the start and the fuel A calculation using a map such as a three-dimensional map of temperature, or a function Da = f (Pca) with the target fuel pressure Pca as a variable, a function Da = f (Pca, t) with the target fuel pressure Pca and the fuel temperature t as variables, A calculation formula such as a function Da = f (Pca, D1, t) using the target fuel pressure Pca, the fixed drive amount D1, and the fuel temperature t as variables may be used.
[0077]
As a result, the discharge amount of the high pressure pump 7 at the next start can be corrected to a discharge amount suitable for the internal combustion engine in which the high pressure pump 7 is mounted. It is possible to reduce the influence on the startability due to the individual difference of the discharge amount related to the valve 19). As a result, it is possible to ensure a predetermined startability. For example, the target drive amount Da is reviewed at each start, and the start-up drive amount D1 is corrected, whereby a predetermined startability can be ensured.
[0078]
In the starting high-pressure pump control S700 described above, the control processing of S702 and S703 is a start that determines whether or not the target internal combustion engine Na has been reached when a predetermined elapsed time T1 is reached after the start of the internal combustion engine. It constitutes sex determination means. Thus, as a method for determining startability, it is possible to determine whether the engine is in a transitional state during start-up, for example, an operating state of an internal combustion engine at a relatively low engine speed immediately after start-up, even if the start-up is not completed. Is possible. The startability determining means determines whether or not the predetermined startability can be ensured by comparing and determining the actual internal combustion engine speed N1 at the predetermined elapsed time T1 and the target internal combustion engine Na, or the predetermined startability. It is possible to make a prediction judgment as to whether or not
[0079]
The startability judging means includes an operating state detecting means 70 and an engine start command detecting means. As a result, the startability determination means can easily detect the start of the internal combustion engine, and no matter how short the predetermined elapsed time T1 after the start of the start is, the actual internal combustion engine speed N1 and the target internal combustion engine Na Can be reliably compared. Therefore, the startability determination means can make a determination for ensuring startability even in a transient state immediately after the start of the start.
[0080]
The control processing from S704 to S706 constitutes a discharge amount correcting means for correcting the discharge amount D1 at the next start according to the actual fuel pressure Pc1 and the actual internal combustion engine speed N1 at a predetermined elapsed time T1. By this discharge amount correcting means, the startability can be improved regardless of the individual difference of the high-pressure pump 7, and a predetermined startability can be secured.
[0081]
The correction of the discharge amount D1 by the discharge amount correcting means is executed when the startability determining means determines that the actual internal combustion engine speed N1 has not reached the target internal combustion engine speed Na. Therefore, it is possible to reduce the load on the discharge amount correction means, that is, the ECU 10, as compared with the case where the discharge amount is corrected regardless of whether the actual internal combustion engine speed N1 is higher or lower than the target internal combustion engine speed Na.
[0082]
The target internal combustion engine rotational speed Na may be any internal combustion engine rotational speed as long as it is within a rotational speed range that occurs in the operating state from the start to the completion of the start.
[0083]
(Third embodiment)
In the third embodiment, as shown in FIG. 8, a cylinder discriminating unit that discriminates a cylinder of the internal combustion engine and a feedback control unit that can control the discharge amount D for each cylinder are provided. FIG. 8 is a flowchart of high-pressure pump control according to the embodiment. In the following embodiments, the same or equivalent components as those in the second embodiment are denoted by the same reference numerals, and description thereof will not be repeated.
[0084]
The cylinder discrimination means includes a crank angle sensor 77 and a rotation speed sensor 71 (see FIG. 2). For example, a signal is transmitted once per rotation of the high-pressure pump 7 by the crank angle sensor 77, and a plurality of signals are transmitted per rotation of the high-pressure pump 7 (for example, 60 times the multiple in the case of four cylinders) by the rotation speed 71. This is a well-known means for knowing a specific cam phase (not shown) corresponding to a specific cylinder of the high-pressure pump 7 when the ECU 10 receives these signals.
[0085]
The feedback control means is a well-known means for controlling the discharge amount D in accordance with the cylinder determined by the cylinder determining means.
[0086]
As shown in FIG. 8, in S801, it is determined whether or not cylinder discrimination can be performed by the cylinder discrimination means. Specifically, it is determined whether at least one of the crank angle sensor 77 and the rotational speed sensor 71 has reached a predetermined signal output (hereinafter referred to as a detectable threshold) or more. If the signal output is equal to or greater than the detectable threshold, it is determined that cylinder discrimination is possible, and the process proceeds to S802. Conversely, if it is equal to or less than the threshold, the process proceeds to S700. Note that the criterion for determining whether or not each cylinder is possible is not limited to the threshold value, and may be a lower limit internal combustion engine speed at which these signals can be detected.
[0087]
In S802, the discharge amount D corresponding to the cylinder is controlled from the relationship between the cylinder of the internal combustion engine detected by the cylinder discrimination means and the specific cam phase corresponding to the cylinder.
[0088]
On the other hand, in S700, the start-time high-pressure pump control described in the second embodiment is performed. That is, a predetermined drive amount D1 is input as the drive amount D at the start, and the discharge amount of the high-pressure pump 7 is adjusted according to the drive amount D1, and the start-up determination means and the discharge amount correction means perform the next start-up. Target drive amount Da is obtained. Thereafter, the process proceeds to S802.
[0089]
In other words, when it is determined by the startability determining means that the target internal combustion engine speed Na has been reached, the discharge amount correcting means is not executed, and the feedback control means executes control of the discharge amount according to the cylinder. As a result, until the startability determining means determines that the predetermined startability has been secured, the learning control for correcting the influence due to the individual difference of the high-pressure pump 7 at the next start can be performed, and the target internal combustion engine speed When it is determined that the predetermined startability has been ensured by reaching Na, correction for improving startability can be performed by feedback control during the start-up, not during the next start-up. For example, according to the set value of the target internal combustion engine speed Na, the startability can be effectively improved in the speed range after the speed Na. Even when the startability determining means does not determine that the predetermined startability has been secured, feedback control can improve the startability in the rotation speed range after the rotation speed Na.
[0090]
Here, in the present embodiment, the target internal combustion engine rotational speed Na is set lower than the lower limit rotational speed Nj (see (a) in S702 of FIG. 7) that allows cylinder discrimination by the cylinder discrimination means. Thereby, the learning control for performing the next start and the feedback control for the correction for improving the startability during the start can be effectively performed, so that the predetermined startability can be efficiently ensured. It is desirable that the target internal combustion engine speed Na is close to the lower limit speed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a schematic system configuration of a common rail fuel injection device to which an accumulator fuel injection device according to a first embodiment of the present invention is applied.
FIG. 2 is a schematic configuration diagram showing a control system in FIG. 1;
3 is a schematic diagram illustrating a flow control valve of the high-pressure pump in FIG. 1. FIG. 3 (a) is a cross-sectional view of the flow control valve, and FIG. 3 (b) is a B direction of FIG. 3 (a). It is an enlarged view which shows the suction port seen from.
4 is a graph showing drive characteristics of an embodiment of the flow control valve of FIG. 3;
FIG. 5 is a flowchart showing a pre-processing for starting high-pressure pump control executed by the ECU shown in FIG. 1;
FIG. 6 is a flowchart of start-time high-pressure pump control according to the first embodiment of the present invention.
FIG. 7 is a flowchart of start-up high-pressure pump control according to the second embodiment of the present invention.
FIG. 8 is a flowchart of high-pressure pump control according to a third embodiment of the present invention.
[Explanation of symbols]
1-4 Injector (fuel injection valve)
5 Common rail
6 Fuel tank
7 High pressure pump
10 ECU (control device, discharge amount control means)
11-14 Solenoid valve for injection period control (injection period variable means)
19 Electromagnetic valve for injection pressure control (injection pressure variable means, flow control valve)
70 Operating state detection means
71 Rotational speed sensor (part of operating state detection means)
81 Fuel pressure sensor (fuel pressure detection means)
A Opening area
D Drive amount
D1 predetermined value (predetermined driving amount)
Ns Predetermined internal combustion engine speed
Na Target internal combustion engine speed
N1 (when the predetermined elapsed time T1 is reached from the start of starting) actual internal combustion engine speed (reached internal combustion engine speed)
Nj Lower limit rotational speed (cylinder discriminating means can discriminate)
Pc Common rail pressure (fuel pressure in common rail 5)
Pca Target fuel pressure
P1 Actual fuel pressure (when reaching a predetermined elapsed time T1 from the start of starting) (Fuel fuel pressure reached)
Ts arrival time
Ta Target start time (predetermined start time)
T1 Predetermined elapsed time
ΔPc / ΔT (increase value of common rail pressure Pc per unit time)
S501 Pre-processing of high-pressure pump control at start-up (control processing for detecting start-up time by starter energization start detecting means)
S600 (S601 to S607) Start-up high-pressure pump control process according to the first embodiment
S700 (S601 and S702 to S706) Start-up high-pressure pump control process according to the second embodiment
S800 (S801, S802 and S700) High-pressure pump control processing according to the third embodiment

Claims (5)

A high-pressure pump that pumps fuel from the fuel tank;
A common rail for accumulating high-pressure fuel discharged from the high-pressure pump;
A plurality of fuel injection valves which are provided for each cylinder of the internal combustion engine and supply high pressure fuel accumulated in the common rail to the combustion chamber of the cylinder;
An operating state detecting means for detecting an operating state of the internal combustion engine;
Fuel pressure detecting means for detecting the fuel pressure of the high-pressure fuel accumulated in the common rail;
A discharge amount control means for controlling a discharge amount of the high-pressure pump according to the operation state detected by the operation state detection means and the fuel pressure detected by the fuel pressure detection means;
When the internal combustion engine is started, the discharge amount control means detects a time required to reach a predetermined internal combustion engine speed by the operating state detection means, and the fuel pressure detection means sets the boosting characteristic of the fuel pressure. An accumulator fuel injection device that detects and increases or decreases the discharge amount at the next start according to the pressure increase characteristic when the arrival time exceeds a predetermined start time. The high-pressure pump includes a flow control valve that adjusts a fuel intake amount pumped from the fuel tank,
The pressure-accumulation fuel injection device according to claim 1, wherein the discharge amount control means changes a drive amount output to the flow control valve.   The pressure accumulation type fuel injection device according to claim 2, wherein the flow control valve is a linear solenoid.   The accumulator fuel injection apparatus according to claim 2 or 3, wherein the drive amount output to the flow control valve is performed by duty control. The boost characteristic is an increase amount of the fuel pressure per unit time,
The discharge amount control means has a predetermined upper limit increase value and a predetermined lower limit increase value. When the boosting characteristic is equal to or higher than the predetermined upper limit increase value, a correction is made to increase the drive amount at the next start-up. The discharge amount at the next start is increased by correcting the discharge amount so as to decrease when the boosting characteristic is equal to or lower than the predetermined lower limit increase value. The pressure accumulation type fuel injection device according to any one of claims 2 to 4.

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