JP2011226303A - High pressure pump control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high pressure pump control device for an internal combustion engine, for preventing the deterioration of fuel injection accuracy by preventing the drop of fuel pressure in a period from reaching target fuel pressure to completing the discrimination of cylinders, thus preventing the worsening of startability and emission.SOLUTION: At a stage before discriminating cylinders, a fuel pressure change amount is used for setting an energizing time so that fuel pressure in a common rail reaches the target fuel pressure at a timing of completing the discrimination of the cylinders. Thus, a period from reaching the target fuel pressure to completing the discrimination of the cylinders can be eliminated to prevent the drop of the fuel pressure in this period.

Description

  The present invention relates to a control device for a high-pressure pump of an internal combustion engine that supplies high-pressure fuel to an injector via a pressure accumulation pipe.

  An accumulator fuel injection device is known as one of fuel injection devices applied to diesel engines and the like. In this device, the fuel boosted by the high-pressure pump is stored in the common rail, and the high-pressure fuel is injected from the injector after the cylinder discrimination is completed. Therefore, at the time of starting the engine, it is necessary to quickly increase the fuel pressure in the common rail (hereinafter referred to as “fuel pressure”) to ensure the target fuel pressure before the completion of cylinder discrimination. Therefore, conventionally, the pressure control valve provided in the high-pressure pump is on-off controlled in anticipation of maximizing the amount of fuel supplied from the high-pressure pump to the common rail at the stage before cylinder discrimination. (Hereafter referred to as “total pumping control”). Although the target fuel pressure can be secured by this total pressure feed control, the target fuel pressure may be reached before the cylinder discrimination is completed, and if the full pressure feed control is continued until the cylinder discrimination is completed, the fuel pressure may increase excessively. . As a technique for preventing this excessive increase in fuel pressure, Patent Document 1 discloses a method of stopping the total pumping control when the fuel pressure in the common rail reaches the target fuel pressure.

Japanese Patent No. 3317202

  However, in the prior art, since the total pressure control is stopped when the target fuel pressure is reached, the total pressure control is stopped even when the target fuel pressure is reached before the cylinder discrimination is completed. Therefore, there has been a problem that the fuel pressure in the common rail decreases during the period from the arrival of the target fuel pressure to the completion of cylinder discrimination. In particular, if full pressure feed control is performed when the fuel temperature is low, the target fuel pressure is often reached at an early stage relative to completion of cylinder discrimination. The reason is that when the fuel temperature is low, the bulk modulus and viscosity of the fuel are high, so that the amount of leakage from the plunger of the high-pressure pump is reduced and the pressure increase speed is increased. Therefore, the period during which the fuel pressure decreases after reaching the target fuel pressure becomes longer. Due to the decrease in fuel pressure during this period, the accuracy (injection amount, atomization, etc.) of fuel injection performed after cylinder discrimination is reduced, and as a result, startability and emission may be deteriorated.

  The present invention has been made in view of the above problems, and provides a high-pressure pump control device for an internal combustion engine that can secure a target fuel pressure when cylinder discrimination is completed and can prevent startability deterioration and emission deterioration. The purpose is to do.

  In order to solve the above problem, the invention according to claim 1 prevents a back flow of fuel discharged from the discharge port, a pump chamber having a fuel intake port and a discharge port, a fuel pressure control valve that opens and closes the suction port side, and the like. A high-pressure pump comprising a check valve, a high-pressure fuel passage for accumulating high-pressure fuel pumped from the high-pressure pump, fuel pressure detecting means for detecting fuel pressure in the high-pressure fuel passage (hereinafter referred to as “fuel pressure”), and at the time of engine start In the stage before completion of cylinder discrimination, a pressure control means for controlling the energization time to the fuel pressure control valve to increase the fuel pressure in the high pressure fuel passage, and the amount of change in the fuel pressure in the high pressure fuel passage that changes due to the discharge of the high pressure pump is detected. The fuel pressure change amount detection means and an energization time control means for setting the energization time according to the fuel pressure change amount in the stage before cylinder discrimination of the engine.

  According to the above configuration, the boosting speed of the fuel pressure in the high-pressure fuel passage can be changed by setting the energization time to the fuel pressure control valve based on the fuel pressure change amount in the stage before cylinder discrimination of the engine. That is, the period until the target fuel pressure is reached can be adjusted by controlling the energization time.

  In the invention according to claim 2, the energization time control means estimates the next fuel pressure change amount or the subsequent fuel pressure change amount based on the first fuel pressure change amount changed by the pressure feed control means (estimated fuel pressure change amount), The energization time to the fuel pressure control valve is set according to the estimated fuel pressure change amount.

  According to the above configuration, the next fuel pressure change amount or the next and subsequent fuel pressure change amounts are estimated based on the first fuel pressure change amount, and the energization time to the fuel pressure control valve is set based on the estimated fuel pressure change amount. Accordingly, it is possible to estimate the next or subsequent fuel pressure change amount in consideration of the fuel information obtained from the first fuel pressure change amount, for example, the volume modulus of elasticity or viscosity. As a result, for example, if it is estimated that the fuel pressure exceeds the target fuel pressure before the cylinder discrimination is completed, the fuel pressure change amount is adjusted by changing the energization time to the fuel pressure control valve, and the desired pressure increase The fuel pressure can be made to reach the target fuel pressure at a speed.

  In the invention according to claim 3, the energization time control means sets the energization time to the fuel pressure control valve so that the fuel pressure in the high pressure fuel passage reaches the target fuel pressure at the timing when the cylinder discrimination is completed. It is characterized by.

  According to the above configuration, the energization time is set so as to reach the target fuel pressure at the timing when the cylinder discrimination is completed. As a result, it is possible to suppress an excessive increase in fuel pressure caused by performing full pressure feed control every time as in the conventional case. Furthermore, since it is possible to eliminate the period from reaching the target fuel pressure to completion of cylinder discrimination, the fuel pressure does not decrease during this period. Therefore, the accuracy is not lowered at the time of fuel injection performed after the completion of cylinder discrimination, and deterioration of startability and emission can be prevented.

  The invention according to claim 4 is characterized in that the timing at which the cylinder discrimination is completed is determined by a predetermined crank angle, and the predetermined crank angle is within a range of two rotations of the crankshaft from the start of starting.

  As a cylinder discrimination technique, a method using a reference signal output from a crank angle sensor in response to rotation of the crankshaft and a cam angle signal output from a cam angle sensor in response to rotation of the camshaft is widely known. Yes. In this method, the timing at which the cylinder discrimination is completed varies depending on the period from when the engine is started until the reference signal and the cam angle signal are detected. Specifically, the reference signal output from the crank angle sensor is output once for one rotation of the crankshaft, that is, 360 ° CA, and the cam angle signal output from the cam angle sensor is for two rotations of the crankshaft, that is, 720. ° Outputs once to CA. Therefore, the timing for completing the cylinder discrimination is within 720 ° CA at the latest. On the other hand, according to the above configuration, the timing at which the cylinder discrimination is completed is determined by the predetermined crank angle within the range in which the crankshaft rotates twice from the start of the start, so the timing at which the target fuel pressure is reached is determined by the cylinder discrimination. It can be set to a timing that is surely completed.

  The invention according to claim 5 is a high pressure comprising a pump chamber having a fuel inlet and outlet, a fuel pressure control valve for opening and closing the inlet side, and a check valve for preventing the backflow of fuel discharged from the outlet. A pump, a high-pressure fuel passage for accumulating high-pressure fuel pumped from the high-pressure pump, fuel pressure detecting means for detecting fuel pressure in the high-pressure fuel passage (hereinafter referred to as “fuel pressure”), and in a stage before completion of cylinder discrimination at the time of engine start , A pressure control means for controlling the energization time to the fuel pressure control valve to increase the fuel pressure in the high pressure fuel passage, a fuel temperature detecting means for detecting the fuel temperature or a fuel temperature estimating means for estimating the fuel temperature, and cylinder discrimination of the engine The preceding stage is characterized by comprising energization time control means for setting the energization time to the fuel pressure control valve in accordance with the fuel temperature obtained by the fuel temperature estimation means or the fuel temperature detection means.

  In the above configuration, the energization time to the fuel pressure control valve is set based on the fuel temperature instead of the fuel pressure change amount. Even if it is such an aspect, the effect similar to the invention of Claim 1 can be acquired.

  The invention according to claim 6 is characterized in that the energization time control means sets the energization time to the fuel pressure control valve so that the amount of fuel supplied to the high-pressure fuel passage decreases as the fuel temperature decreases.

  When the fuel temperature is low, the volume modulus of elasticity and viscosity of the fuel decrease, so the discharge amount of the high-pressure pump increases and the pressure increase speed increases. On the other hand, according to the above configuration, the energization time to the fuel pressure control valve is set so that the fuel supply amount from the high pressure pump to the high pressure fuel passage decreases as the fuel temperature decreases. As a result, even when the fuel temperature is low and the pressure increase speed is high, the pressure can be increased without causing an excessive increase in the fuel pressure with respect to the target fuel pressure.

  In the invention according to claim 7, the energization time control means sets the energization time to the fuel pressure control valve so that the fuel pressure in the high pressure fuel passage reaches the target fuel pressure at the timing when the cylinder discrimination is completed. It is characterized by that.

  According to the above configuration, the energization time is set so as to reach the target fuel pressure at the timing when the cylinder discrimination is completed. Therefore, the same effect as that of the invention described in claim 3 can be obtained.

Schematic configuration diagram of the entire high-pressure pump control system Flow chart showing high pressure pump control processing procedure at start-up Flow chart showing processing procedure of pumping control Time chart showing transition states corresponding to the processing procedure of FIG. The flowchart which shows the processing procedure of the pumping control in 2nd Embodiment. Control map for calculating discharge volume The flowchart which shows the process sequence of the pumping control in 3rd Embodiment. Control map for calculating energization time Time chart showing the transition state corresponding to the processing procedure of FIG.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of the entire high-pressure pump control system. In this embodiment, a high-pressure pump applied to a four-cylinder diesel engine is a control target.

  As shown in FIG. 1, each cylinder of the engine 1 has an injector 2 for injecting fuel, a common rail 3 (high-pressure fuel passage in the claims) for accumulating high-pressure fuel injected from the injector 2, and fuel in the common rail 3. And a fuel tank 6. The fuel tank 6 includes an electronic control device 5 (hereinafter referred to as “ECU”) that electronically controls the injector 2 and the high pressure pump 4.

  The fuel in the fuel tank 6 is pumped up by an electromagnetically driven low pressure pump 7 and introduced into the engine driven high pressure pump 4 via a fuel pipe 8. The introduced fuel is increased in pressure by the high-pressure pump 4 and is pumped to the common rail 3. The high pressure fuel pumped to the common rail 3 is stored in the common rail 3 in a high pressure state, and then directly injected into the cylinder from the injector 2 attached to the upper part of each cylinder of the engine 1. In addition, the arrow in FIG. 1 has shown the flow of the fuel.

  Hereinafter, the configuration of the high-pressure pump 4 will be described with reference to FIG. The high pressure pump 4 is provided with a cylinder 41 in the pump body, and a plunger 42 is inserted in the cylinder 41 so as to be reciprocally movable. One end of the plunger 42 is in contact with the cam 44 by the biasing force of the spring 43. The cam 44 is fixed to a camshaft 10 connected to the crankshaft 9 via a belt, and is rotationally driven by the rotation of the crankshaft 9 accompanying engine driving. This rotation causes the plunger 42 to reciprocate within the cylinder 41.

  A pressure chamber 45 (a pump chamber in the claims) is provided at the other end (on the opposite cam side) of the plunger 42. Fuel is sucked into the pressurizing chamber 45 in accordance with the movement of the plunger 42, and the sucked fuel is discharged from the pressurizing chamber 45. Specifically, when the plunger 42 moves to the side of increasing the volume of the pressurizing chamber 45 (downward), the fuel pumped up from the fuel tank 6 by the low-pressure pump 7 along with the movement of the plunger 42 is reduced. The air is sucked into the pressurizing chamber 45 through the (suction port referred to in the claims). On the other hand, when the plunger 42 moves to the side of reducing the volume of the pressurizing chamber 45 (upward), the fuel in the pressurizing chamber 45 is pressurized and discharged from the pressurizing chamber 45 with the movement.

  In this embodiment, the cam 44 is formed in a circular shape protruding in four directions. As described above, the plunger 42 is in contact with the cam 45 by the spring 43, and the reciprocating motion of the plunger 42 is performed by the rotation of the cam 44 fixed to the cam shaft 10. When one protrusion formed on the cam 44 comes into contact with the plunger 42 and is separated from the plunger 42, the plunger 42 reciprocates four times for one rotation of the cam shaft 10. That is, the fuel is discharged four times to the common rail 3.

  An electromagnetic valve 11 (a fuel pressure control valve in the claims) is attached to the opposite side of the plunger 42 across the pressurizing chamber 45 in the axial direction of the plunger 42. The electromagnetic valve 11 includes a valve body 48 that opens and closes a communicating portion 47 that communicates with the pressurizing chamber 45, an armature 49 fixed to the valve body 48, a spring 50 that biases the armature 49 toward the pressurizing chamber 45, The coil 51 is configured to attract the armature 49 when energized. The electromagnetic valve 11 opens and closes the pressurizing chamber 45 and the low pressure passage 46. Specifically, when the coil 51 is not energized, the valve body 48 is urged toward the pressurizing chamber 45 by the urging force of the spring 50, and the fuel from the low-pressure passage 46 to the pressurizing chamber 45 is energized. Inflow is possible. On the other hand, when the coil 51 is energized, the armature 49 is attracted to the coil 51, and the communication portion 47 is closed by the valve body 48, so that fuel from the low pressure passage 46 to the pressurizing chamber 45 can be obtained. Inflow is stopped.

  The fuel discharged from the pressurizing chamber 45 is supplied to the common rail 3 through the high-pressure passage 52 (discharge port in the claims). A check valve 53 is provided in the middle of the high pressure passage 51, that is, between the pressurizing chamber 45 and the common rail 3 to prevent the backflow of fuel discharged from the pressurizing chamber 45. The check valve 53 is configured not only to prevent the backflow of fuel but also to open when the fuel pressure in the pressurizing chamber 45 exceeds a predetermined pressure. As a result, fuel having a predetermined pressure or higher can be supplied to the common rail 3. A plurality of injectors 2 for injecting fuel into each cylinder are connected to the common rail 3, and high-pressure fuel accumulated in the common rail 3 is supplied to each injector 2. A fuel pressure sensor 12 is provided on the common rail 3, and the fuel pressure in the common rail 3 is detected by the sensor 12.

  The crankshaft 9 of the engine 1 is provided with a crank angle sensor 13 that outputs a crank angle signal at every predetermined crank angle of the engine 1 (for example, at a cycle of 30 ° CA). The rotational speed NE is detected. A cam angle sensor 14 is provided on the cam shaft 10 that rotates in synchronization with the crankshaft 9 to detect the cam angle. Further, the fuel pipe 8 is provided with a fuel temperature sensor 15 for detecting the temperature of the fuel.

  The ECU 5 is mainly composed of a microcomputer having a known structure including a CPU that performs control processing and arithmetic processing, various control programs, and a storage device (memory such as ROM and RAM) that stores data. The ECU 5 controls the above-described injector 2 and high-pressure pump 4 based on signals from the above-described various sensors.

  Further, the ECU 5 is provided with a fuel pressure change amount calculating means for calculating the fuel pressure change amount ΔP (i) in the common rail that changes due to the discharge of the high pressure pump 4. Specifically, the change amount of the fuel pressure is calculated from the difference between the detection value of the fuel pressure sensor 12 before discharge and the detection value after discharge.

  The cylinder discrimination of the engine 1 is performed based on the output values of the crank angle sensor 13 and the cam angle sensor 14 described above. Specifically, a reference signal output from the crank angle sensor 13 corresponding to a singular point (for example, top dead center) of a specific cylinder, and a cam output from the cam angle sensor 14 once every two rotations of the crankshaft 9. Cylinder discrimination is performed based on the angle signal. Therefore, the timing at which cylinder discrimination is completed varies depending on the period from when the engine is started until the reference signal and cam angle signal are detected. The reference signal output from the crank angle sensor 13 is output once per one rotation of the crankshaft 9, that is, 360 ° CA, and the cam angle signal output from the cam angle sensor 14 is two rotations of the crankshaft 9, that is, 720. ° Outputs once to CA. Therefore, the timing for completing the cylinder discrimination is within 720 ° CA at the latest.

  Here, the full pressure feed control performed before cylinder discrimination will be described. As described above, the total pressure feed control is to control the electromagnetic valve 11 provided in the high pressure pump 4 so that the amount of fuel supplied from the high pressure pump 4 to the common rail 3 is maximized. Specifically, the solenoid valve 11 is opened (energized OFF) at the timing when the plunger 42 becomes the top dead center, and the solenoid valve 11 is closed (energized ON) at the timing when the plunger 42 becomes the bottom dead center. The amount of fuel sucked into the pressurizing chamber 45 and the amount of fuel discharged from the pressurizing chamber 45 are maximized. However, the timing when the plunger 42 becomes the top dead center / bottom dead center cannot be accurately detected until the cylinder discrimination is completed. For this reason, in the present embodiment, the timing at which the plunger 42 becomes the top dead center / bottom dead center before cylinder discrimination is controlled with the expectation, so that the fuel supply amount from the high pressure pump 4 to the common rail is maximized. This is called pumping control.

  Next, a process executed by the ECU 5 when the engine is started will be described with reference to FIG.

  When the engine is started, it is not known in which stroke each cylinder was stopped when the engine was stopped last time. Therefore, it is necessary to determine which cylinder is allowed to inject fuel after cranking is started. Therefore, first, in step 100, the above-described cylinder discrimination is started. Next, in step 200, it is determined whether cylinder discrimination is completed. If it is determined that the cylinder discrimination has not been completed, in step 300, a pressure control (a pressure control means in the claims) is performed to control the energization time to the electromagnetic valve 11 so as to increase the fuel pressure in the common rail. On the other hand, if it is determined in step 200 that the cylinder discrimination has been completed, the routine proceeds to step 400 where the pressure in the common rail is increased by the fuel pressure FB control. If the fuel pressure in the common rail has reached the target fuel pressure Pt by the pressure feed control in step 300, or if the fuel pressure in the common rail has reached the target fuel pressure Pt by the fuel pressure FB control in step 400, the process proceeds to step 500. In step 500, the high-pressure fuel boosted in step 300 or 400 is injected from the injector 2 into each cylinder. The engine 1 is started by such processing.

  Next, the processing procedure of the pressure control performed in step 300 will be described with reference to FIG.

  First, in step 301, the first pumping (total pumping control) by the high-pressure pump 4 described above is performed. Next, the routine proceeds to step 302, where the fuel pressure change amount ΔP (1) is calculated from the fuel pressure P (0) before the first pumping and the fuel pressure (1) after the first pumping.

  Next, in step 303, the amount of fuel supplied into the common rail by pressure feeding, in other words, the discharge amount Q (1) of the high-pressure pump 4 is obtained. Specifically, the discharge amount Q (1) is obtained by map calculation of the fuel pressure P (0) before pressure feeding and the rotation speed NE (0) before pressure detected from the crank angle sensor 13.

  Then, the process proceeds to step 304, and the volume elastic modulus E (1) of the fuel at the first pumping is calculated. The bulk modulus E (1) is calculated based on the following theoretical formula.

ΔP (i) = E (i) × Q (i) / V
V is a fixed value indicating the volume of the common rail. The volume modulus E (1) is calculated by substituting the fuel pressure change amount ΔP (1) obtained in step 302 and the discharge amount Q (1) obtained in step 303 into this theoretical formula.

  Next, in step 305, the next discharge amount Q (2) is calculated. Similarly to step 303, the discharge amount Q (2) is obtained by map calculation of the fuel pressure P (1) after the initial pumping and the rotational speed NE (1) before the pumping detected from the crank angle sensor 13.

  In step 306, an estimated fuel pressure change amount ΔPe (2) that changes due to the next discharge is estimated. In the theoretical formula, the bulk modulus E (1) obtained in step 304 is fixed, and the next discharge amount Q (2) obtained in step 305 is substituted. Thus, the next fuel change amount ΔPe (2) is estimated.

  In step 307, the energization time (DUTY) to the solenoid valve 11 at the next discharge is determined according to the estimated fuel pressure change amount ΔPe (2). Based on this DUTY, the solenoid valve 11 is energized at step 308, and the common rail is boosted.

  Then, the process proceeds to step 309, and the fuel pressure P (2) after the second discharge is detected. Next, in step 310, it is determined whether or not the fuel pressure P (2) has reached the target fuel pressure Pt. If the target fuel pressure Pt has been reached, this routine ends. On the other hand, if the target fuel pressure Pt has not been reached, i = i + 1 (i = 3 in this example) is set in step 311 to perform the third discharge, and the flow proceeds to step 303. Thereafter, Step 303 to Step 310 are repeatedly performed until the fuel pressure P (i) reaches the target fuel pressure Pt. The pumping control is performed by the above processing procedure.

  In the present embodiment, fuel injection is not executed until the fuel pressure in the common rail reaches the target fuel pressure Pt. That is, even if the cylinder discrimination is completed during the pressure increase (step 301 to step 309) by the pressure feed control (step 300), the fuel injection control (step 500) is executed if the target fuel pressure Pt has not been reached. First, boosting is performed with priority.

  Next, the transition state corresponding to the processing procedure of pumping control is demonstrated based on FIG.

  As described above, the cylinder discrimination is completed within 720 ° CA at the latest from the start of the start. In FIG. 4, the timing when the cylinder discrimination is completed is the time when 540 ° CA has elapsed since the start of the start. That is, the energization time is set so that the fuel pressure reaches the target fuel pressure Pt when the fuel is pumped from the high pressure pump 4 to the common rail 3 three times.

  Cranking is started in the initial state (t0), and cylinder discrimination (step 100) in FIG. At this time, the fuel pressure P (0) is low, and the solenoid valve 11 is not energized. Then, fuel is supplied to the pressurizing chamber 45 of the high pressure pump 4 by the low pressure pump 7 between t0 and t1.

  Then, the initial pumping (step 301) shown in FIG. 3 is performed between t1 and t2, and the fuel pressure is increased from P (0) to P (1). Next, the processing of steps 302 to 307 is performed between t2 and t3. Then, between t3 and t4, the solenoid valve 11 is energized based on the energization time (DUTY) calculated in step 307 (step 308), and the fuel pressure is increased from P (1) to P (2). The Since the fuel pressure P (2) has not yet reached the target fuel pressure Pt at t4, the processing of steps 302 to 307 is performed again between t4 and t5. Then, between t5 and t6, the solenoid valve 11 is energized based on the energization time calculated in step 307. The fuel pressure is increased from P (2) to P (3) by this third pumping, and at t6, the fuel pressure P (3) reaches the target fuel pressure Pt. Since t6 is the timing when the cylinder discrimination is completed, the fuel injection control (step 500 in FIG. 1) can be performed immediately after t6.

  Next, the effect of this embodiment is demonstrated.

  As described above, in order to secure the injection fuel pressure performed after cylinder discrimination, it is necessary to rapidly increase the fuel pressure before completion of cylinder discrimination. For this reason, conventionally, a full pressure feed control is performed every time before cylinder discrimination, and the total pressure feed control is stopped when the target fuel pressure is reached. On the other hand, according to the above configuration, the boosting speed of the fuel pressure in the common rail is changed by setting the energizing time to the solenoid valve 11 based on the fuel pressure change amount in the stage before the cylinder discrimination of the engine 1. Further, the energization time is set so as to reach the target fuel pressure at the timing when the cylinder discrimination is completed.

  As a result, it is possible to suppress an excessive increase in fuel pressure caused by performing full pressure feed control every time as in the conventional case. Furthermore, since it is possible to eliminate the period from reaching the target fuel pressure to completion of cylinder discrimination, the fuel pressure does not decrease during this period. Accordingly, the accuracy of fuel injection performed after the completion of cylinder discrimination is not lowered, so that it is possible to prevent startability deterioration and emission deterioration.

  In addition, the previous fuel pressure change amount ΔP (i−1) is used as a parameter for calculating the energization time of the current solenoid valve. Specifically, the next fuel pressure change amount ΔPe (i + 1) is estimated according to the bulk modulus E (i) calculated from the previous fuel pressure change amount ΔP (i−1). The energization time is calculated based on the estimated fuel pressure change amount ΔPe (i + 1). As described above, since the bulk modulus E (i) indicating the closest fuel state at the time of the next pumping is used, the energization time can be calculated by reflecting the change in the discharge amount due to the temperature change of the fuel. Further, since the volume elastic modulus E (i) is calculated from the previous fuel pressure change amount ΔP (i−1), it is not necessary to use the fuel temperature sensor 15 for detecting the fuel temperature.

[Second Embodiment]
In the following embodiments including the second embodiment, the same or corresponding configurations as the configurations of the already described embodiments are denoted by the same reference numerals, and redundant description thereof is omitted.

  The second embodiment is different from the first embodiment in the number of energization times and the timing, and specifically as follows.

  In the first embodiment, the calculation time of the energization time to the solenoid valve 11 is performed every time after pumping, such as after the first pumping, after the second pumping, and after the third pumping. Since the timing for completing the cylinder discrimination is two rotations (720 ° CA) of the crankshaft 9 at the latest, the plunger 42 of the high-pressure pump 4 driven by the camshaft 10 that rotates 1/2 with respect to the crankshaft 9 is the maximum. Perform four times of pumping. That is, the energization time is calculated up to three times excluding after the fourth pumping that reaches the target fuel pressure Pt. On the other hand, in 2nd Embodiment, the timing which calculates energization time is only once after the first pumping.

  Hereinafter, the processing procedure of the pressure control in the second embodiment will be described with reference to FIG.

  As shown in FIG. 5, steps 301 to 304 are the same as those in the first embodiment. In short, the first pumping by the high-pressure pump 4 (step 301) is performed, and the fuel pressure change amount ΔP (1) is calculated based on the detected value of the fuel pressure sensor 12 before and after pumping (step 302). Then, the discharge amount Q (1) of the high-pressure pump 4 is obtained by map calculation of the fuel pressure P (0) before pumping and the rotational speed NE (0) before pumping detected from the crank angle sensor 13 (step 303). The bulk modulus E (1) of the fuel at the time of the first pumping is calculated (step 304).

  After calculation of the bulk modulus E (1), in step 601, fuel pressure change amounts ΔPe (2) and ΔPe (3) after the next time are estimated. Specifically, the bulk modulus E (i) of the above theoretical formula is fixed to the bulk modulus E (1) at the time of the initial pumping, and Q (2) and Q (3) are changed. The fuel pressure change amount ΔPe (2) can be calculated from E (1) and Q (2) as in the first embodiment. Further, the fuel pressure change amount ΔPe (3) can be calculated from E (1) and Q (3). Q (3) can be calculated using the map of the fuel pressure and the rotational speed NE shown in FIG. 6 by setting the fuel pressure P (2) to P (1) + ΔPe (2).

  After calculating the estimated fuel pressure changes ΔPe (2) and ΔPe (3), the process proceeds to step 602, and the second and third times so that the target fuel pressure Pt = P (1) + ΔPe (2) + ΔPe (3). The energization time is calculated. That is, how much the second energization time and the third energization time are reduced with respect to the first energization time is calculated to reach the target fuel pressure.

  Then, the process proceeds to step 603, and the second and third pumping operations are performed based on the energization time calculated in step 602. In step 604, the fuel pressure sensor 12 detects the current fuel pressure P (3). In step 605, it is determined whether the fuel pressure P (3) has reached the target fuel pressure Pt, and this routine is terminated.

  Next, the function and effect of the second embodiment will be described.

  According to the above configuration, the number of times of calculating the energization time is different from that of the first embodiment, and the energization time of the plurality of times to the solenoid valve 11 to be performed thereafter is collectively calculated by one calculation after the initial pumping. .

  The number of times of pumping corresponding to the timing at which the arbitrarily determined cylinder discrimination is completed, for example, when the timing at which cylinder discrimination is completed is set to 540 ° CA, the number of times of pumping is 3 times and 720 ° When CA is determined, it is 4 times. That is, after the initial pumping, the pumping is performed twice at 540 ° CA, and the pumping is performed three times at 720 ° CA. The energization time for a plurality of times of pumping performed after the initial pumping is calculated after the first pumping.

  Thereby, it is possible to comprehensively determine a plurality of energization times until the target fuel pressure Pt is reached. That is, the degree of freedom of distribution of the second, third, and fourth energization times can be improved. Further, since the energization time is set using the fuel pressure change amount ΔPe (i) and the target fuel pressure is reached at the timing when the cylinder discrimination is completed, the same effect as in the first embodiment can be obtained.

[Third Embodiment]
In 1st Embodiment and 2nd Embodiment, the energization time to the solenoid valve 11 was set based on the fuel variable. On the other hand, in 3rd Embodiment, the energization time to the solenoid valve 11 is set based on fuel temperature.

  Hereinafter, the processing procedure of the pressure control in the third embodiment will be described with reference to FIG.

  First, at step 701, the fuel temperature sensor 15 detects the fuel temperature T (0) and the fuel pressure P (0). Next, the routine proceeds to step 702, where the energization time to the solenoid valve 11 is calculated using the map of the fuel temperature T (0) and the fuel pressure P (0) shown in FIG. As described above, when the fuel temperature T is low, the volume elastic modulus E and the viscosity of the fuel are lowered, so that the discharge amount of the high-pressure pump 4 is increased and the pressure increase speed is increased. On the other hand, when the fuel temperature T is high, the volume elastic modulus E and the viscosity of the fuel increase, so that the discharge amount of the high-pressure pump 4 decreases and the pressure increase speed decreases. Therefore, as shown in FIG. 8, the energization time is set to be shorter as the fuel temperature T is lower and longer as the fuel temperature T is higher. Further, when the fuel temperature T becomes higher than a predetermined value, the energization time is the longest, that is, the entire pumping control is performed over the entire period (at the time of pumping). When the fuel temperature T exceeds a predetermined value, the target fuel pressure Pt cannot be reached unless the energization time to the solenoid valve 11 is maximized due to a decrease in the pressure increase speed, or the target fuel pressure Pt cannot be reached even if the energization time is maximized. Occurs. In such a case, the energization time is set to the longest in order to increase the fuel pressure in the common rail as much as possible.

  Next, the solenoid valve 11 is energized in step 703 based on the energization time calculated in step 702. In step 704, the current fuel pressure P (i + 1) is detected, and the process proceeds to step 705. In step 705, it is determined whether the detected current fuel pressure P (i + 1) has reached the target fuel pressure Pt. When the target fuel pressure Pt is reached, this routine is terminated. On the other hand, if the target fuel pressure Pt has not been reached, at step 706, i = i + 1 is set, and the routine proceeds to step 701. Then, the processing from step 701 to step 705 is repeated until the fuel pressure reaches the target fuel pressure Pt.

  Next, a transition state corresponding to the processing procedure of the pressure feed control will be described with reference to FIG. As in the first embodiment, the timing at which the cylinder discrimination is completed is set to the time when 540 ° CA has elapsed from the start of the start, and when the pumping from the high pressure pump 4 to the common rail 3 is performed three times, the fuel pressure P becomes the target fuel pressure Pt. An example is shown in which the energization time is set so as to reach.

  Cranking is started in the initial state (t0), and cylinder discrimination (step 100) in FIG. At this time, the fuel pressure P (0) is low, and the solenoid valve 11 of the high-pressure pump 4 is not energized. Then, the fuel temperature T is detected (step 701) between t0 and t1, and the energization time is calculated based on the map shown in FIG. 8 (step 702). And between t1-t2, electricity supply with respect to a solenoid valve is implemented based on the calculated electricity supply time (step 703). Next, between t2 and t3, the current fuel pressure P (1) is detected (step 703) and compared with the target fuel pressure Pt. In this example, since the target fuel pressure has not been reached, the fuel temperature is detected again, the energization time is calculated again, and the solenoid valve is energized at t3 to t4, and the fuel pressure is changed from P (1) to P (2). And boosted. Then, from t4 to t5, the current fuel pressure P (2) is detected and compared with the target fuel pressure Pt. Since the fuel pressure P (2) has not yet reached the target fuel pressure at t4, the processing of step 701 and step 702 is performed again between t4 and t5. Then, between t5 and t6, the solenoid valve 11 is energized based on the energization time calculated in step 702. By this third pumping, the fuel pressure is increased from P (2) to P (3), and at t6, the fuel pressure P reaches the target fuel pressure Pt. In this example, since t6 is the timing when the cylinder discrimination is completed, the fuel injection control (step 500) can be performed without causing a decrease in the fuel pressure.

  Next, the function and effect of the third embodiment will be described.

  According to the above configuration, unlike the first embodiment in which the next energization time is calculated from the fuel pressure change amount detected based on the theoretical equation, the current fuel temperature is detected and energization is performed by performing a preset map calculation. Time can be calculated. Thereby, compared with 1st Embodiment, energization time can be calculated easily. Specifically, in the first embodiment, after calculating the fuel pressure change amount, after obtaining the high-pressure pump discharge amount Q and the bulk modulus E based on the theoretical formula, the next fuel pressure change amount is estimated and further converted into the energization time. On the other hand, in the third embodiment, after the fuel temperature is detected, the energization time can be calculated only by a preset map calculation. Further, since the energization time is set and the target fuel pressure is reached at the timing when the cylinder discrimination is completed, the same effect as in the first embodiment can be obtained.

  The present invention is based on the technical idea that the fuel pressure in the common rail reaches the target fuel pressure at the timing when the cylinder discrimination is completed, and as a means thereof, the fuel pressure change amount is used in the first embodiment and the second embodiment. A method for setting the energization time is shown, and a method for setting the energization time using the fuel temperature in the third embodiment is shown. According to each of the above embodiments, the fuel pressure is prevented from lowering during the period from reaching the target fuel pressure to the completion of cylinder discrimination, thereby preventing the fuel injection accuracy from being lowered, and thus the high pressure of the internal combustion engine that prevents startability deterioration and emission deterioration. A pump controller can be provided.

[Other Embodiments]
-In 1st Embodiment and 2nd Embodiment, in order to obtain | require a volume elastic modulus, it calculated by substituting fuel pressure change amount (DELTA) P and pump discharge amount Q to a theoretical formula. Thereby, the bulk modulus E could be obtained without using a fuel temperature sensor. However, the fuel temperature may be detected using a fuel temperature sensor, and the volume elastic modulus E may be obtained by calculating the map between the fuel temperature and the fuel pressure. In the case of such a configuration, the pump discharge amount Q can be calculated by substituting the fuel pressure change amount ΔP and the bulk modulus E into the theoretical formula.

  In the third embodiment, the fuel temperature is detected at the timing before each pumping, and the energization time is calculated each time. In short, the energization time is calculated a plurality of times as in the first embodiment. However, as shown in the second embodiment, it is also possible to estimate a plurality of energization times performed thereafter at once. That is, also in 3rd Embodiment, it can be set as the aspect which calculates collectively the energization time of multiple times until target fuel pressure is reached | attained at the timing before the first pumping.

  In the third embodiment, the fuel temperature is directly detected using the fuel temperature sensor 12, but the fuel temperature is estimated using the cooling water temperature obtained by the water temperature sensor (fuel temperature estimating means in the claims). It is good.

1 engine (internal combustion engine)
3 Common rail (high pressure fuel passage)
4 High pressure pump 5 ECU
9 Crankshaft 11 Solenoid valve (fuel pressure control valve)
12 Fuel pressure sensor (Fuel pressure detection means)
15 Fuel temperature sensor (Fuel temperature detection means)
46 Low pressure passage (suction port)
52 High-pressure passage (discharge port)
53 Check valve

Claims (7)

A high-pressure pump comprising a pump chamber having a fuel suction port and a discharge port, a fuel pressure control valve for opening and closing the suction port side, and a check valve for preventing a back flow of fuel discharged from the discharge port;
A high-pressure fuel passage for accumulating high-pressure fuel pumped from the high-pressure pump;
Fuel pressure detecting means for detecting fuel pressure in the high-pressure fuel passage (hereinafter referred to as “fuel pressure”);
A pressure feed control means for controlling an energization time to the fuel pressure control valve to increase the fuel pressure in the high pressure fuel passage in a stage before completion of cylinder discrimination at the time of engine start;
A fuel pressure change amount detecting means for detecting a fuel pressure change amount in the high pressure fuel passage which is changed by discharge of the high pressure pump;
A high-pressure pump control device for an internal combustion engine, comprising: energization time control means for setting the energization time according to the fuel pressure change amount in a stage before completion of cylinder discrimination of the engine.   The energization time control means estimates the next fuel pressure change amount or the next or subsequent fuel pressure change amount based on the first fuel pressure change amount changed by the pressure feed control means (estimated fuel pressure change amount), and according to the estimated fuel pressure change amount 2. The high-pressure pump control device for an internal combustion engine according to claim 1, wherein an energization time for the fuel pressure control valve is set.   The energization time control means sets the energization time to the fuel pressure control valve so that the fuel pressure in the high pressure fuel passage reaches a target fuel pressure at a timing when cylinder discrimination is completed. The high-pressure pump control device for an internal combustion engine according to claim 1 or 2.   4. The internal combustion engine according to claim 3, wherein the timing at which the cylinder discrimination is completed is determined by a predetermined crank angle, and the predetermined crank angle is within a range of two rotations of the crankshaft from the start of starting. High pressure pump control device. A high-pressure pump comprising a pump chamber having a fuel suction port and a discharge port, a fuel pressure control valve for opening and closing the suction port side, and a check valve for preventing a back flow of fuel discharged from the discharge port;
A high-pressure fuel passage for accumulating high-pressure fuel pumped from the high-pressure pump;
Fuel pressure detecting means for detecting fuel pressure in the high-pressure fuel passage (hereinafter referred to as “fuel pressure”);
A pressure feed control means for controlling an energization time to the fuel pressure control valve to increase the fuel pressure in the high pressure fuel passage in a stage before completion of cylinder discrimination at the time of engine start;
Fuel temperature detecting means for detecting the fuel temperature or fuel temperature estimating means for estimating the fuel temperature;
In the pre-cylinder discrimination stage of the engine, it is provided with energization time control means for setting an energization time to the fuel pressure control valve according to the fuel temperature obtained by the fuel temperature estimation means or the fuel temperature detection means. A high-pressure pump control device for an internal combustion engine.   6. The energization time control means sets the energization time to the fuel pressure control valve so that the amount of fuel supplied to the high pressure fuel passage decreases as the fuel temperature decreases. A high-pressure pump control device for an internal combustion engine.   The energization time control means sets the energization time to the fuel pressure control valve so that the fuel pressure in the high pressure fuel passage reaches a target fuel pressure at a timing when cylinder discrimination is completed. The high-pressure pump control device for an internal combustion engine according to claim 5 or 6.

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