JP2010101246A - Fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device maintaining fuel injection precision over a long period of time. <P>SOLUTION: An ECU 4 for controlling a fuel injection valve 2 having a piezoelectric drive unit 24 for driving a needle 12 for controlling open/close of an injection hole 44, and a load sensor unit 23 for outputting a load signal according to a load acting on the piezoelectric drive unit 24, when it is decided that an internal combustion engine is in cold startup, calibrates the load sensor unit 23, based on charging energy accumulated in the piezoelectric drive unit 24 in a startup operation state or an idle operation state, a load acting on the load sensor unit 23 at this time, reference charging energy, and load stored in a memory means 5a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for a fuel injection device using a piezoelectric drive unit.

  The piezoelectric drive unit that controls the drive of the valve member by driving at least one of the injection functional parts including the valve member that intermittently injects fuel from the injection hole, and the piezoelectric drive unit that is driven when the piezoelectric drive unit is driven There is known a fuel injection control device that is provided in a fuel injection device that includes a load sensor unit that outputs an output signal corresponding to a load and controls a piezoelectric drive unit (see Patent Document 1).

In this fuel injection control device, valve closing / opening supplied to the piezoelectric drive unit based on an output signal from the load sensor unit is performed in order to suppress variations in fuel injection characteristics due to characteristic changes and dimensional tolerances of the piezoelectric drive unit. The signal is corrected for learning.
JP-A-10-288119

  However, in the above-described conventional fuel injection device, a piezoelectric body is used as the load sensor unit. For this reason, as with the piezoelectric drive unit, the load sensor unit also deteriorates with time. In particular, unlike the piezoelectric drive unit, the load sensor unit is not configured to be applied with a high voltage. For this reason, the load sensor unit including the piezoelectric body is more likely to cause polarization degradation than the piezoelectric drive unit. When polarization deterioration occurs, an output signal output from the load sensor unit for a predetermined load changes. This causes a problem that the piezoelectric drive unit cannot be appropriately controlled.

  Therefore, calibration of the load sensor unit is necessary. Generally, in order to improve the accuracy of sensor calibration, it is required to eliminate disturbance to the sensor as much as possible. Here, since the load sensor unit is housed in the fuel injection device, the charging energy accumulated in the piezoelectric drive unit that varies greatly according to the operating state of the internal combustion engine, the fuel pressure introduced into the fuel injection device, It is easily affected by heat from the internal combustion engine and heat generated by driving the piezoelectric driving unit.

  For this reason, if the load sensor unit is calibrated without considering these situations, the load sensor unit is affected by the charging energy, fuel pressure, heat from the internal combustion engine, and heat from the piezoelectric drive unit. The accuracy of calibration may be reduced.

  When the calibration accuracy is lowered, the controllability of the piezoelectric drive unit is lowered, and the controllability of the ejection function component driven by the piezoelectric drive unit is also lowered. As a result, it becomes difficult to maintain the accuracy of the fuel injection characteristics such as the injection timing and the injection amount over a long period of time.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a fuel injection control device that can maintain fuel injection accuracy over a long period of time.

According to the first aspect of the present invention, there is provided a body having an injection hole that is mounted on an internal combustion engine and injects fuel introduced into the combustion chamber of the internal combustion engine, and is accommodated in the body, and fuel injection from the injection hole is performed. An injection functional component including an intermittent valve member, and a piezoelectric body that is accommodated in the body, expands by accumulating charging energy, and contracts by discharging the accumulated charging energy, and includes at least one of the injection functional components A piezoelectric drive unit that controls the drive of the valve member by driving one of the two, and a load signal that is accommodated in the body and stores charge energy in the piezoelectric drive unit according to the load acting on the piezoelectric drive unit. A fuel injection control device for controlling a piezoelectric drive unit based on a load signal from a load sensor unit, comprising a load sensor unit including a piezoelectric body to output,
Cold start determination means for determining the cold start of the internal combustion engine, and accumulated in the piezoelectric drive unit during at least one of the start operation state from the start of the internal combustion engine to the self-sustaining operation or the no-load operation state Charging means, an acquisition means for acquiring a load signal output from the load sensor unit when the charging energy is stored in the piezoelectric driving unit, reference charging energy, and the reference charging energy stored in the piezoelectric driving unit The storage means that stores the reference load signal output from the load sensor unit and the cold start determination means determines that the internal combustion engine is cold start, and the charging energy acquired by the acquisition means And a calibration means for calibrating the load sensor unit based on the load signal and the reference charging energy and the reference load signal.

  According to the present invention, it is possible to grasp that the internal combustion engine is in the cold start by the cold start determination means. According to this determination means, it can be estimated that the load sensor unit housed in the fuel injection device mounted on the internal combustion engine is also at substantially the same temperature as the outside air temperature. Further, during cold start, it is difficult to be affected by heat from the internal combustion engine. For this reason, it can be considered that the temperature of the load sensor part is in a relatively stable state.

  The acquisition means outputs the charging energy accumulated in the piezoelectric drive unit in at least one of the starting operation state and the no-load operation state, and is output from the load sensor unit when the charging energy is accumulated. The load signal is acquired. The charging energy in the starting operation state and the no-load operation state is more stable than the charging energy in other operation states (for example, high load and low load operation states). For this reason, the load signal obtained at that time is also stable.

  The calibration means is in a cold start where the temperature of the load sensor part is relatively stable, in a reference charge energy, a reference load signal, a start operation state, or a no-load operation state as a reference. Based on the stable charging energy and load signal, the load sensor unit is calibrated. Since the calibration means calibrates the load sensor unit under these conditions, it is possible to eliminate as much as possible disturbance to the sensor unit that hinders improvement in calibration accuracy. Thereby, the accuracy of calibration of the load sensor unit can be improved. As a result, the controllability of the piezoelectric drive unit can be maintained over a long period of time, and consequently the accuracy of the fuel injection characteristics can be maintained over a long period of time.

  The invention described in claim 2 has correction coefficient calculation means for calculating a temperature correction coefficient based on the temperature of the load sensor unit, and the calibration means uses the temperature correction coefficient calculated by the correction coefficient calculation means. In addition, the load sensor unit is calibrated.

  In general, a piezoelectric body has temperature characteristics, and the magnitude of an output signal changes according to temperature even if the load acting on the load sensor unit is the same.

  According to the present invention, the calibration unit calibrates the load sensor unit by adding the temperature correction coefficient calculated by the correction coefficient calculation unit based on the temperature of the load sensor unit. In addition, calibration can be performed, and the accuracy of calibration is further improved.

  The invention according to claim 3 is characterized in that the charging energy accumulated in the piezoelectric drive unit in the starting operation state and the no-load operation state is a predetermined energy amount corresponding to each operation state. .

  According to the present invention, when the charging energy accumulated in the piezoelectric drive unit in the starting operation state and the no-load operation state is a predetermined energy amount corresponding to each operation state, the charging energy used in calibration is reduced. It can be made more stable. As a result, the calibration accuracy is greatly improved.

  According to a fourth aspect of the present invention, the acquisition means includes a predetermined charging energy at start-up corresponding to the start-up operation state, a predetermined no-load charging energy corresponding to the no-load operation state, and a piezoelectric drive unit. Each load signal output from the load sensor unit when the charge energy at start-up and the charge energy at no load is accumulated is acquired, and the calibration means acquires the charge energy at start-up and charge at no load obtained by the acquisition means. The load sensor unit is calibrated based on energy and each load signal.

  According to the present invention, the calibration means outputs the charge energy at the start and the charge energy at the no load, and the load sensor unit outputs the charge energy at the start and the charge energy at the no load in the piezoelectric drive unit. Since the load sensor unit is calibrated based on the load signal, a plurality of points can be used for calibration. For this reason, the accuracy of calibration of the load sensor portion can be improved.

  According to a fifth aspect of the present invention, the acquisition means includes a predetermined no-load charging energy corresponding to the no-load operation state and the load sensor unit when the no-load charging energy is accumulated in the piezoelectric drive unit. The output load signal is acquired, and the calibration unit calibrates the load sensor unit based on the no-load charging energy and the load signal acquired by the acquisition unit.

  Exhaust gas regulations under no-load operation are stricter than those under high-load operation. In the no-load operation state, the fuel injection amount injected from the fuel injection device is very small. For this reason, the ratio of the dispersion | variation in the injection quantity with respect to the request | requirement injection quantity in this driving | running state is high compared with a high load driving | running state. For this reason, it is necessary to improve the accuracy of the fuel injection characteristics in this operating state.

  According to this invention, the calibrating means is based on the no-load charging energy and the load signal output from the load sensor unit when the no-load charging energy is accumulated in the piezoelectric drive unit. Since calibration is performed, the accuracy of calibration of the load sensor unit at least in a no-load operation state is high. For this reason, the accuracy of the fuel injection characteristic in the no-load operation state can be ensured.

  In the invention according to claim 6, the load signal used when the calibration means calibrates the load sensor unit is a unit that is output until the charging energy is released from the maximum load signal indicating the largest value. It is characterized by a stable load signal with the smallest amount of change per hour.

  According to the present invention, the calibration means is used when calibrating the stable load signal with the smallest amount of change per unit time output from the maximum load signal showing the largest value until the charging energy is released. Therefore, the calibration accuracy of the load sensor unit can be improved as compared with the case of using a load signal at a time when the amount of change is large.

  The invention according to claim 7 is characterized in that the cold start determination means includes an outside air temperature acquisition means for acquiring the outside air temperature, and an engine temperature acquisition means for acquiring the engine temperature of the internal combustion engine, and the acquired outside air temperature It is characterized in that the cold start is determined by comparing the engine temperature.

  According to the present invention, the cold start determination means can determine whether or not the internal combustion engine is cold started by a simple determination method of comparing the acquired outside air temperature and the engine temperature.

  The invention according to claim 8 is characterized in that the engine temperature acquisition means acquires a cooling water temperature for cooling the internal combustion engine or a lubricating oil temperature used for lubricating the internal combustion engine.

  According to the present invention, the coolant temperature or the lubricating oil temperature generally required for controlling the internal combustion engine is acquired, and any one of them is used as the engine temperature. Therefore, a separate sensor or the like is not used. The engine temperature can be obtained. Further, by utilizing the invention according to claim 8 in the invention according to claim 2 together with the invention according to claim 7, a temperature sensor or the like for detecting the temperature of the load sensor portion is not provided in the fuel injection device. In both cases, the temperature of the load sensor unit can be grasped.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the component corresponding in each embodiment.

(First embodiment)
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings. FIG. 1 shows an overall configuration of a fuel supply device 1 including a fuel injection control device 4 according to a first embodiment of the present invention. The fuel supply device 1 supplies fuel to each cylinder of a multi-cylinder internal combustion engine such as a diesel engine. The fuel handled by the fuel supply device 1 is not limited to diesel fuel, and may be gasoline fuel.

  The fuel supply device 1 includes a fuel injection valve 2, a drive circuit 3, an electronic control device 4 (hereinafter referred to as “ECU”), and the like. The fuel injection valve 2 corresponds to a “fuel injection device” described in the claims, and the electronic control device 4 corresponds to a “fuel injection control device” described in the claims.

  The fuel injection valve 2 directly injects fuel into each cylinder using high-pressure fuel stored in a pressure accumulator (not shown). Of the fuel supplied to the fuel injection valve 2, the fuel not used for fuel injection is returned to the fuel tank 10 through the return path 8.

  The fuel injection valve 2 includes a nozzle 11, a control valve 18, an actuator unit 21, and the like, and these components are accommodated in a body 40 formed in a rod shape.

  The body 40 has a fuel inlet 41 into which high-pressure fuel from the pressure accumulator is introduced, and a fuel outlet 42 connected to the return path 8. A housing portion 43 is formed on one end side of the body 40 in the axial direction. The accommodating portion 43 accommodates a nozzle 11 that controls fuel injection and non-injection.

  The nozzle 11 has a needle 12, a nozzle spring 16, and a nozzle cylinder 17. The needle 12 is slidably held in the housing portion 43. A nozzle hole 44 that communicates with the fuel inlet 41 via a high-pressure fuel passage 46 is formed at one axial end of the housing 43.

  A valve seat 45 on which the seat portion 13 formed on the needle 12 is seated is formed on the fuel inlet portion 41 side of the nozzle hole 44. When the seat 13 is seated on the valve seat 45, the flow of fuel to the nozzle hole 44 is closed, and the fuel injection from the nozzle hole 44 is stopped. When the seat portion 13 is separated from the valve seat 45, the flow of fuel to the nozzle hole 44 is allowed, and fuel is injected from the nozzle hole 44.

  The nozzle cylinder 17 is formed in a cylindrical shape, and a piston portion 14 formed at an end portion of the needle 12 opposite to the seat portion 13 is slidably and liquid-tightly inserted on the inner peripheral side. is doing. The nozzle cylinder 17 forms a control chamber 52 in which the internal fuel pressure is switched between high pressure and low pressure together with the piston portion 14 and the inner wall of the accommodating portion 43.

  A flange portion 15 is formed between the seat portion 13 and the piston portion 14 of the needle 12, and a nozzle spring 16 is provided between the flange portion 15 and the nozzle cylinder 17. The nozzle spring 16 urges the needle 12 in the direction in which the seat portion 13 is seated on the valve seat 45, that is, in the valve closing direction.

  The needle 12 is urged in the valve closing direction by the fuel pressure in the control chamber 52. Further, the needle 12 is urged in a direction in which the seat portion 13 is separated from the valve seat 45, that is, in a valve opening direction, by the high pressure fuel guided from the fuel inlet portion 41 to the accommodating portion 43 through the high pressure fuel passage 46. The movement of the needle 12 in the valve closing direction or the valve opening direction is determined by the balance of the fuel pressure in the control chamber 52, the fuel pressure of the high-pressure fuel guided to the housing portion 43, and the urging force of the nozzle spring 16.

  The control valve 18 is housed in a valve chamber 53 formed in the intermediate portion of the body 40 in the axial direction, and performs switching control between high pressure and low pressure of the fuel pressure in the control chamber 52. The valve chamber 53 is connected to a communication passage 50 that always communicates with the control chamber 52, a high-pressure communication passage 47 that branches off from the housing portion 43, and a low-pressure fuel passage 48. A common orifice 51 is provided in the communication passage 50.

  The control valve 18 includes a valve body 19 and a valve spring 20. The valve body 19 communicates between the valve chamber 53 and the low-pressure fuel passage 48 by separating from and seating on the low-pressure side seat surface 54 formed around the opening of the low-pressure fuel passage 48 in the inner wall of the valve chamber 53. Control the shut-off.

  Further, the valve element 19 is separated from and seated on the high-pressure side seat surface 55 formed around the opening of the high-pressure communication passage 47 in the inner wall of the valve chamber 53, so that the valve body 19 is located between the valve chamber 53 and the high-pressure communication passage 47. Controls communication and disconnection.

  The valve body 19 is separated from the high-pressure side seat surface 55 when seated on the low-pressure side seat surface 54, and conversely when the seat 19 is separated from the low-pressure side seat surface 54. Sitting at 55. The valve spring 20 urges the valve body 19 in a direction to be seated on the low pressure side seat surface 54.

  The actuator portion 21 is accommodated in an actuator chamber 56 formed on the other end side of the body 40 in the axial direction. The actuator chamber 56 is connected to the low pressure fuel passage 48 via the low pressure communication passage 49.

  A back pressure valve 9 for controlling the pressure on the low pressure fuel passage 48 side is disposed in the return path 8 that connects the fuel tank 10 and the fuel outlet 42. Whereas the pressure of the high pressure fuel stored in the pressure accumulator is 100 MPa or more, the back pressure valve 9 controls the fuel pressure on the low pressure fuel passage 48 side to about 1 MPa.

  The actuator unit 21 includes a piezoelectric actuator 22 and a displacement transmission unit 30. The piezoelectric actuator 22 is mainly configured by laminating a plurality of piezoelectric bodies, and expands and contracts due to charge and discharge.

  The displacement transmission unit 30 transmits the expansion / contraction displacement of the piezoelectric actuator 22 to the valve body 19 of the control valve 18. The displacement transmission unit 30 includes an actuator cylinder 31, a first piston 32, and a second piston 33. The first piston 32 and the second piston 33 are slidably and liquid-tightly inserted on the inner peripheral side of the actuator cylinder 31. A liquid chamber 34 filled with fuel is formed between the first piston 32 and the second piston 33.

  The first piston 32 is biased toward the piezoelectric actuator 22 by the first spring 35. The first piston 32 is directly driven by the piezoelectric actuator 22. When the piezoelectric actuator 22 is extended, the first piston 32 moves toward the liquid chamber 34, so that the fuel pressure in the liquid chamber 34 increases.

  The second piston 33 is urged toward the valve body 19 side of the control valve 18 by the second spring 36. The second piston 33 is mechanically connected to the valve body 19. When the second piston 33 receives the fuel pressure in the liquid chamber 34 and moves toward the valve body 19, the valve body 19 is moved to the valve chamber 19. 53 and the low-pressure fuel passage 48 are moved in a communication direction.

  When the piezoelectric actuator 22 is extended, the first piston 32 moves in the direction of the liquid chamber 34. Then, the fuel pressure in the liquid chamber 34 increases. The second piston 33 receives the increased fuel pressure in the liquid chamber 34, communicates the valve body 19 between the valve chamber 53 and the low pressure fuel passage 48, and connects the valve chamber 53 and the high pressure fuel passage 46. Move in the direction that cuts off the communication between them. As a result, the valve body 19 communicates between the valve chamber 53 and the low pressure fuel passage 48 and blocks communication between the valve chamber 53 and the high pressure fuel passage 46.

  When the piezoelectric actuator 22 contracts, the fuel pressure in the liquid chamber 34 decreases. The second piston 33 moves to the first piston 32 side by the urging force of the valve spring 20 of the control valve 18. The urging force of the valve spring 20 is larger than the urging force of the second spring 36. The valve body 19 blocks communication between the valve chamber 53 and the low-pressure fuel passage 48 and communicates between the valve chamber 53 and the high-pressure communication passage 47.

  The piezoelectric actuator 22 has a piezoelectric body unit 22a and a metal housing 22b. The piezoelectric unit 22a is formed by laminating a piezoelectric layer P and an internal electrode layer E. The piezoelectric unit 22a extends by applying a voltage from the internal electrode layer E to the piezoelectric layer P. And a load sensor unit 23 for detecting a load acting upon the operation. The load sensor unit 23 is a sensor that uses the piezoelectric effect of the piezoelectric layer P. A voltage signal corresponding to the load is extracted from the internal electrode layer E constituting the load sensor unit 23.

  The piezoelectric actuator 22 is connected to the drive circuit 3. The drive circuit 3 supplies a charging current to the piezoelectric driving unit 24 and increases the charging voltage of the piezoelectric driving unit 24, whereby charging energy is accumulated in the piezoelectric driving unit 24. The extension amount of the piezoelectric drive unit 24 changes according to the charging energy. An ECU 4 is connected to the drive circuit 3. The ECU 4 generates a charging control signal corresponding to the charging energy to the piezoelectric driving unit 24 and the energization timing to the piezoelectric driving unit 24 set based on various information from various sensors acquired by the ECU 4, and sends the charging control signal to the piezoelectric driving unit 24. Output. Here, the charging energy accumulated in the piezoelectric driving unit 24 is obtained by measuring the charging current and the charging voltage flowing through the piezoelectric driving unit 24 during the charging process, and integrating the product of the measured charging current and the charging voltage over time. Is.

  Further, the load sensor unit 23 is connected to the drive circuit 3. The charge and voltage signals from the load sensor unit 23 are input to the ECU 4 via the drive circuit 3. The ECU 4 is also connected to various sensors (not shown) for detecting the intake air amount, accelerator pedal depression amount, internal combustion engine speed, fuel pressure in the accumulator, and the like, and signals from these various sensors are input. It is like that.

  In the present embodiment, a multi-switching method (hereinafter referred to as “MS method”) is adopted as a method for charging and discharging the piezoelectric drive unit 24 of the piezoelectric actuator 22.

  The drive circuit 3 includes a switching element (not shown) capable of directly disconnecting the DC power supply in a path for energizing the piezoelectric actuator 22 from a DC power supply (not shown) via an inductor (not shown). Yes. In the MS system, the switching element is turned on / off a plurality of times based on a charge control signal from the ECU 4 to charge the piezoelectric drive unit 24 of the piezoelectric actuator 22 in several times.

  While the switching element is on, a charging current that gradually increases flows to the piezoelectric drive unit 24. When the switching element is turned off, a charging current that gradually decreases to the piezoelectric drive unit 24 by the flywheel action flows. Thus, while the charging current flows through the piezoelectric driving unit 24, the charging voltage in the piezoelectric layer P of the piezoelectric driving unit 24 continues to increase. The detailed driving method and circuit configuration of the MS method are well known, for example, in Japanese Patent Laid-Open No. 2001-53348.

  The ECU 4 includes an MPU 5, an AD conversion unit 6, a DSP 7, and the like. Further, the MPU 5 includes a memory unit 5a having a storage function such as acquired data and a control program. The memory means 5a is composed of, for example, a ROM, an EEPROM, and a RAM. The MPU 5 performs arithmetic processing according to a control program stored in the memory unit 5a. The memory means 5a corresponds to “storage means” recited in the claims.

  The ECU 4 calculates the load generated by the piezoelectric drive unit 24 by performing high-speed A / D processing on the charge and voltage signals input from the load sensor unit 23 in the AD conversion unit 6, and calculates the calculated load and Based on signals input from various sensors, a charge control signal to be output to the piezoelectric drive unit 24 is generated.

  Next, the operation of the fuel supply device 1 will be described. When the piezoelectric actuator 22 is not extended, the second piston 33 is moved to the first piston 32 side by the biasing force of the valve spring 20 of the control valve 18. As a result, the valve body 19 receives the fuel pressure in the valve chamber 53, moves in the direction of the low pressure fuel passage 48 and is seated on the low pressure side seat surface 54, and the communication between the valve chamber 53 and the low pressure fuel passage 48 is established. The valve chamber 53 and the high-pressure communication passage 47 are communicated with each other. Thereby, the fuel pressure in the valve chamber 53 becomes equal to the fuel pressure in the high pressure fuel passage 46, and the fuel pressure in the control chamber 52 communicating with the valve chamber 53 becomes equal to the fuel pressure in the high pressure fuel passage 46. .

  At this time, the force in the valve opening direction generated in the needle 12 due to the fuel pressure in the high-pressure fuel passage 46 acting around the needle 12 is due to the fuel pressure in the control chamber 52 acting on the piston portion 14 of the needle 12. It is smaller than the sum of the force in the valve closing direction generated at the needle 12 and the force in the valve closing direction generated at the needle 12 due to the urging force of the nozzle spring 16. Therefore, the seat portion 13 of the needle 12 is seated on the valve seat 45, and fuel injection from the injection hole 44 is stopped.

  When the piezoelectric drive unit 24 of the piezoelectric actuator 22 is extended by the charge control signal from the ECU 4, the first piston 32 moves toward the liquid chamber 34 as the piezoelectric drive unit 24 is extended. Then, the fuel pressure in the liquid chamber 34 increases. The second piston 33 receives the increased fuel pressure and moves toward the valve body 19 side. The valve body 19 moves in the direction of the high-pressure communication passage 47 and is seated on the high-pressure side seat surface 55, and communicates between the valve chamber 53 and the low-pressure fuel passage 48, and between the valve chamber 53 and the high-pressure communication passage 47. Block communication between them. Then, the fuel in the control chamber 52 is returned to the fuel tank 10 via the common orifice 51, the communication passage 50, the valve chamber 53, and the low pressure fuel passage 48. As a result, the fuel pressure in the control chamber 52 decreases. At this time, the load sensor unit 23 detects the load F acting on the piezoelectric drive unit 24 from the first and second pistons 32 and 33 and the valve body 19 of the control valve 18 when the piezoelectric drive unit 24 extends.

  At this time, the force in the valve opening direction generated in the needle 12 due to the fuel pressure in the high-pressure fuel passage 46 acting around the needle 12 is due to the fuel pressure in the control chamber 52 acting on the piston portion 14 of the needle 12. It is larger than the sum of the force in the valve closing direction and the force in the valve closing direction due to the urging force of the nozzle spring 16. Therefore, the seat portion 13 of the needle 12 is separated from the valve seat 45, and fuel is injected from the injection hole 44.

  Thereafter, when the piezoelectric drive unit 24 contracts due to the discharge control signal from the ECU 4, the second piston 33 moves to the first piston 32 side by the urging force of the valve spring 20 as the piezoelectric drive unit 24 contracts. As a result, the valve body 19 is seated on the low pressure side seat surface 54, shuts off communication between the valve chamber 53 and the low pressure fuel passage 48, and communicates between the valve chamber 53 and the high pressure communication passage 47. As a result, the high pressure fuel from the pressure accumulator is introduced into the control chamber 52 via the high pressure fuel passage 46, the high pressure communication passage 47, the valve chamber 53, the communication passage 50, and the common orifice 51.

  Thereby, the fuel pressure in the control chamber 52 rises again. Therefore, the force in the valve opening direction generated at the needle 12 is smaller than the force in the valve closing direction generated at the needle 12, and the seat portion 13 of the needle 12 is seated on the valve seat 45. As a result, fuel injection from the nozzle hole 44 is stopped. By repeatedly expanding and contracting the piezoelectric actuator 22, fuel injection from the injection hole 44 is interrupted.

  In the present embodiment, the nozzle 11, the control valve 18, and the displacement transmission unit 30 correspond to “injection functional parts” recited in the claims.

  Next, the operation state of the control valve 18 driven by the ECU 4, the drive circuit 3, the piezoelectric drive unit 24 of the piezoelectric actuator 22 and the piezoelectric drive unit 24 when injecting fuel from the fuel injection valve 2 is shown in FIG. This will be described using a time chart. FIG. 2 is a time chart showing the operating state of the piezoelectric drive unit 24 in the piezoelectric actuator 22 and the valve element 19 of the control valve 18.

  The ECU 4 generates an injection permission signal that permits fuel injection from the desired fuel injection valve 2. The injection permission signal is generated based on various information such as the intake air amount, the accelerator pedal depression amount, the internal combustion engine speed, and the fuel pressure in the accumulator, which are acquired by the ECU 4. The ON period of the injection permission signal is set so that the injection can be performed at the optimal injection amount and at the optimal timing for the desired fuel injection valve 2.

  When the injection permission signal is turned on at time T 0, the ECU 4 generates a charge control signal for controlling the drive circuit 3 and outputs it to the drive circuit 3. Specifically, the charge control signal is a signal that repeats ON / OFF a plurality of times. While the charge control signal is on, the above-described switching element is turned on, and a charging current that gradually increases flows to the piezoelectric drive unit 24. While the charge control signal is off, the switching element is turned off, and a charging current that gradually decreases to the piezoelectric drive unit 24 by the flywheel action flows. This operation is performed a plurality of times.

  Each time this operation is performed, the charging voltage of the piezoelectric drive unit 24 gradually increases. This rise continues until the charge control signal ends. Predetermined charging energy is accumulated in the piezoelectric drive unit 24 by these series of operations. The piezoelectric drive unit 24 expands as the charging voltage increases. At this time, the load sensor unit 23 detects the load F acting on the piezoelectric drive unit 24 from the first and second pistons 32 and 33 and the valve body 19 of the control valve 18 when the piezoelectric drive unit 24 extends. The load sensor unit 23 outputs an output signal corresponding to the magnitude of the load F described above.

  When the supply of charging current from the drive circuit 3 to the piezoelectric drive unit 24 is started from time T0, the load F gradually increases. When the time T reaches the first time T1 and the load F indicates the first load F1, the valve body 19 is separated from the low-pressure side seat surface 54.

  When the valve body 19 is separated from the low pressure side seat surface 54, the valve chamber 53 and the low pressure fuel passage 48 communicate with each other, and the fuel pressure in the valve chamber 53 is discharged to the low pressure fuel passage 48. In a state where the valve body 19 is not seated on either the low pressure side seat surface 54 or the high pressure side seat surface 55, the valve body 19 is attached to the low pressure side seat surface 54 due to the differential pressure between the valve chamber 53 and the low pressure fuel passage 48. No force is generated. For this reason, the load F falls until the time T reaches the second time T2. When the time T reaches the second time T2 and the load F indicates the second load F2, the valve body 19 contacts the high-pressure side seat surface 55. Since the valve body 19 stops moving any more, the load F after the second time T2 rises again.

  The ECU 4 can determine whether or not the valve body 19 is separated from the low-pressure side seat surface 54 by comparing the first load F1 and the second load F2.

  Here, even if the valve body 19 comes into contact with the high pressure side seat surface 55 and the load F shows a value slightly increased from the second load F2, the valve body 19 is separated from the high pressure side seat surface 55. Since the fuel pressure of the high-pressure communication passage 47 that is energized in the seating direction is constantly acting, it cannot be estimated that the valve body 19 is reliably seated on the high-pressure side seat surface 55. In order to estimate that the valve body 19 is securely seated on the high-pressure side seat surface 55, the valve body 19 is pressed more strongly against the high-pressure side seat surface 55, and the load F needs to exhibit a certain value. .

  The load F used as the index is the third load F3. When the ECU 4 detects that the time T has reached the third time T3 and the load F exceeds the third load F3, the ECU 4 estimates that the valve body 19 is securely seated on the high-pressure side seat surface 55. After the third time T3, the state in which the valve body 19 is seated on the high-pressure side seat surface 55 is maintained. As a result, the seat portion 13 of the needle 12 is separated from the valve seat 45, and fuel is injected from the injection hole 44.

  Here, in the present embodiment, by increasing the charging energy accumulated in the piezoelectric drive unit 24, the valve body 19 is pressed against the high-pressure side seat surface 55, and the valve body 19 is securely seated on the high-pressure side seat surface 55. Yes. Specifically, by increasing the ON time of the charging control signal, the accumulated charging energy is increased, and the force for pressing the valve body 19 against the high-pressure side seat surface 55 is ensured. On the other hand, in order to weaken the pressing force, the accumulated charge energy is lowered by shortening the ON time of the charge control signal.

  Since the valve body 19 is pressed against the high-pressure side seat surface 55 in accordance with the accumulated charging energy, the load F continues to rise after the third time T3. The load F indicates the maximum load Fp after a predetermined time, and then converges to the stable load Fa. The maximum load Fp and the stable load Fa change according to the supplied charging energy. Here, the stable load Fa is a load F that minimizes the amount of change per unit time until the accumulated charging energy is released from the maximum load Fp.

  When the fourth time T4 is reached after a predetermined time has elapsed since the injection permission signal was turned on, the injection permission signal is turned off. When the injection permission signal is turned off, a discharge control signal (not shown) is output from the ECU 4 to the drive circuit 3. When receiving the discharge control signal, the drive circuit 3 performs control to release the charging energy accumulated in the piezoelectric drive unit 24. Thereby, the load F falls to the state before time T0. Accordingly, the valve body 19 is separated from the high-pressure side seat surface 55 and is seated on the low-pressure side seat surface 54. As a result, the seat portion 13 of the needle 12 is seated on the valve seat 45, and fuel injection from the injection hole 44 is stopped.

  Here, the communication between the valve chamber 19 and the high-pressure communication passage 47 from the time T0 in the time from when charging to the piezoelectric drive unit 24 is started (time T0) to when injection is started. The operating time ΔT, which is the third time T3 until the power is cut off, is affected by the piezoelectric drive unit 24. This operating time ΔT changes due to variations among individual piezoelectric drive units 24 and deterioration over time. As the operating time ΔT changes, the operating characteristics of the needle 12 change, and the accuracy of the fuel injection characteristics such as the fuel injection timing and the injection amount of the fuel injection valve 2 decreases.

  In the present embodiment, the operation time ΔT is adjusted based on the load F from the load sensor unit 23 obtained by operating the piezoelectric drive unit 24. This prevents a decrease in controllability of the piezoelectric drive unit 24 due to variations among individuals and deterioration over time. Thus, the deterioration of the controllability of the piezoelectric drive unit 24 is prevented, thereby preventing the accuracy of fuel injection characteristics from being lowered.

  As described above, in FIG. 2, the operation states of the ECU 4, the drive circuit 3, the piezoelectric drive unit 24, and the control valve 18 from when the seat portion 13 of the needle 12 is separated until it is seated again have been described. When injection is performed before and after the main injection in one fuel stroke, the operation shown in FIG. 2 is performed according to the number of injections.

  Here, in the present embodiment, the fuel pressure injected from the fuel injection valve 2 is changed in accordance with the starting operation state, the no-load operation state (hereinafter referred to as “idle operation state”), the normal operation state, and the like of the internal combustion engine. ing. This fuel pressure is changed by adjusting the fuel pressure in the accumulator. For example, in the idle operation state, the fuel injection amount is smaller than that in the normal operation. For this reason, in the idle operation state, the fuel pressure in the pressure accumulator is set to be relatively low.

  For this reason, the force which presses the valve body 19 against the high-pressure side seat surface 55 can be made relatively small. That is, the charging energy accumulated in the piezoelectric drive unit 24 can be made relatively low. Accordingly, the third load F3 as an index for estimating that the above-described valve body 19 is seated on the high-pressure side seat surface 55 is set low, and whether or not the valve body 19 is seated on the high-pressure side seat surface 55 is determined. Judgment.

  On the other hand, since it is necessary to improve the startability of the internal combustion engine in the start operation state, it is necessary to operate the fuel injection valve 2 reliably. For this reason, the charging energy accumulated in the piezoelectric drive unit 24 is relatively high, and the valve body 19 is reliably seated on the high-pressure side seat surface 55. For this reason, the maximum load Fp and the stable load Fa described above change according to the operating state of the internal combustion engine.

  Here, the starting operation state refers to a state from the start of the starting operation of the internal combustion engine until the internal combustion engine shifts to a self-sustaining operation, and the idle operation state refers to a substantially unloaded state in which the accelerator pedal is not depressed. State.

  Next, a series of operations from starting to stopping the internal combustion engine will be described using the control flow of FIG. FIG. 3 is a control flow from the start to the stop of the internal combustion engine.

  This control flow is started when the ECU 4 detects that an ignition switch (not shown) is turned on.

  As shown in FIG. 3, in step S10 (hereinafter simply referred to as “S10”, the same applies to other steps), a drive signal is output to a drive circuit (not shown) of a starter (cell motor). Operates. As a result, the crankshaft of the internal combustion engine rotates.

  In S20, it is determined that the starter is in operation, so that the operation state is determined to be a start operation state, and the drive circuit 3 includes a start time charge control signal and a start time discharge control signal. A control signal is output. When receiving the control signal, the drive circuit 3 accumulates the charging energy at the time of starting in the piezoelectric drive unit 24 of the predetermined fuel injection valve 2. In the present embodiment, the amount of charging energy at start-up is predetermined.

  In S30, it is determined whether or not the starter has stopped. Through this process, it can be determined that the internal combustion engine has escaped from the starting operation state and has shifted to a self-sustained operation in which fuel burns in the combustion chamber. In the present embodiment, the starter stops when it shifts to a self-sustained operation based on crankshaft rotation fluctuation, torque fluctuation, and the like. In this embodiment, it is determined whether or not the internal combustion engine has shifted to a self-sustained operation by detecting the operation state of the starter, but has shifted to a self-sustained operation by detecting a crankshaft rotation fluctuation or torque fluctuation. It may be determined whether or not.

  If it is determined in S30 that the starter is still operating, the process returns to S20, and the start time control signal is output to the drive circuit 3 again. If it is determined in S30 that the starter has stopped, the process proceeds to S40.

  In S40, assuming that the operation state has shifted to the idle operation state, an idle control signal including an idle charge control signal and an idle discharge control signal is output to the drive circuit 3. When the drive circuit 3 receives this control signal, it accumulates idling charging energy in the piezoelectric drive unit 24 of the predetermined fuel injection valve 2. In the present embodiment, the amount of charging energy during idling is determined in advance.

  In S50, it is determined whether or not the accelerator pedal is depressed from information on the accelerator pedal depression amount input to the ECU 4. By executing this process, it is possible to determine whether or not the vehicle has escaped from the idle operation state and has shifted to the normal operation state according to the accelerator pedal depression amount. In the present embodiment, it is determined whether or not the engine is in the idle maneuvering state based on the accelerator pedal depression amount, but may be determined based on the internal combustion engine speed. Further, if the vehicle model is equipped with a throttle valve device, the determination may be made by receiving a signal from an idle switch provided in the throttle valve device.

  If it is determined in S50 that the accelerator pedal is not depressed, the process returns to S40, and the idle control signal is output to the drive circuit 3 again. If it is determined in S50 that the accelerator pedal has been depressed, the process proceeds to S60.

  In S60, a normal control signal including a normal charge control signal and a normal discharge control signal is output to the drive circuit 3 in order to control the internal combustion engine in accordance with the depression amount of the accelerator pedal.

  In S70, it is determined whether or not the ignition switch is off. By executing this processing, it can be determined whether or not the internal combustion engine has been stopped. If it is determined in S70 that the ignition switch is off, this control flow ends. If it is determined that the ignition switch is on, the process returns to S60, and the normal time control signal is continuously output to the drive circuit 3.

  Next, calibration of the load sensor unit 23 will be described with reference to FIGS. FIG. 4 is a control flow when the load sensor unit 23 is calibrated. FIG. 5 is a graph showing the relationship between charging energy accumulated in each piezoelectric drive unit 24 at the time of factory shipment and after deterioration (before calibration) and the load at that time. The broken line in FIG. 5 shows the state of the piezoelectric drive unit 24 at the time of factory shipment, and the solid line shows the state of the piezoelectric drive unit 24 after deterioration (before calibration). FIG. 6 is a temperature characteristic diagram of the load sensor unit 23.

  This control flow is started when the ECU 4 detects that the ignition switch is turned on.

  As shown in FIG. 4, in S110, the outside air temperature Tat is acquired based on the output signal from the outside air temperature sensor 60 (see FIG. 1). Subsequently, in S120, based on an output signal from a cooling water temperature sensor 61 (see FIG. 1) for detecting the cooling water temperature of the internal combustion engine, a lubricating oil temperature sensor 62 (for detecting the lubricating oil temperature of the internal combustion engine). The oil temperature To is acquired based on the output signal from (see FIG. 1). Furthermore, in S130, it is determined whether or not the acquired water temperature Tw and oil temperature To are substantially the same as the outside air temperature Tat. If it is determined that the water temperature Tw and the oil temperature To are substantially the same as the outside air temperature Tat, the process proceeds to S140. Otherwise, the load sensor unit 23 receives the heat of the internal combustion engine and performs an appropriate calibration. This control flow ends. In the present embodiment, the processing in S120 corresponds to “engine temperature acquisition means” recited in the claims.

  By executing the process of S130, it is possible to determine the cold start of the internal combustion engine. In the present embodiment, the processing in S130 corresponds to “cold start determination means” described in the claims. In the present embodiment, it is determined whether the internal combustion engine is cold-started by comparing both the water temperature Tw and the oil temperature To with the outside air temperature Tat, but only the water temperature Tw and the oil temperature To The cold start may be determined only from the above. In the present embodiment, the cold start is determined based on whether or not the acquired water temperature Tw and oil temperature To are substantially the same as the outside air temperature Tat. This is a result of adding detection errors of the cooling water temperature sensor 61, the lubricating oil temperature sensor 62, and the outside air temperature sensor 60, and the water temperature Tw or the oil temperature To is the outside air temperature Tat depending on these detection errors. What is necessary is just to determine the range which can be considered as appropriate.

  In S140, it is determined whether or not a start-up charge control signal is output to the drive circuit 3. If it is determined that the start-up charge control signal is output to the drive circuit 3, the process proceeds to S150, and if it is determined that the start-up charge control signal is not output, the start-up charge control signal is output. The process of S140 is repeatedly executed until

  In S150, the load Fas of main injection out of a plurality of injections performed during one combustion cycle, and the starting charging energy Eas at that time are acquired. The load Fas is a load F corresponding to the load Fa shown in FIG. 2, and is a load F when the charging energy Eas at the time of start-up is accumulated in the piezoelectric driving unit 24. The load Fas and the starting charging energy Eas acquired in S150 are temporarily stored in the memory means 5a provided in the ECU 4. In the present embodiment, the processing in S150 corresponds to “acquiring means” described in the claims.

  In S160, it is determined whether the number of acquired loads Fas satisfies the required number of data. In the present embodiment, the number of necessary data is n = 1. This required number of data is determined based on the relationship between the number of revolutions of the crankshaft when the starter is operated and the time required to shift to the self-sustaining operation when cranking the internal combustion engine. For example, when the friction of the internal combustion engine is maximum and the voltage of the battery that supplies power to the starter is the lower limit value, the rotation speed during cranking is about 50 rpm. If it takes about 3 seconds to shift to the self-sustained operation in this state, there are two opportunities to obtain the load Fas. Thus, even if the conditions for starting the internal combustion engine are bad, the load Fas that can be acquired is two times, and in this embodiment, the number of necessary data is set to n = 1.

  If the number of acquired loads Fas satisfies the required number of data in the process of S160, the process proceeds to S170, and if not, the process returns to S150 again.

  In S170, the load Fasav and the starting charging energy Easav, which are average values of the load Fas and the starting charging energy Eas acquired in S150, are calculated. Then, the calculated load Fasav and starting charging energy Easav are temporarily stored in the memory means 5a. When the acquired load Fas and the starting charging energy Eas are one, this processing is not necessary.

  In S180, it is determined whether or not an idling charge control signal is output to the drive circuit 3. If it is determined that the idling charge control signal is output to the drive circuit 3, the process proceeds to S190, and if it is determined that the idling charge control signal is not output, the idling charge control signal is output. Until it is done, the process of S180 is repeatedly executed.

  In S190, the main injection load Faa of the multiple injections performed during one combustion cycle and the idling charging energy Eaa at that time are acquired. The load Faa is a load F corresponding to the load Fa shown in FIG. 2, and is a load F when the charging energy Eaa during idling is accumulated in the piezoelectric driving unit 24. The load Faa and idling charging energy Eaa acquired in S190 are temporarily stored in the memory means 5a provided in the ECU 4. In the present embodiment, the processing in S190 corresponds to “acquiring means” described in the claims.

  In S200, it is determined whether or not the number of acquired loads Faa satisfies the required number of data. In the present embodiment, the number of necessary data is about n = 10. The more data that is acquired, the higher the accuracy of calibration. However, since the internal combustion engine continues to operate even during the acquisition of the load Faa, the temperature of the load sensor unit 23 rises due to the heat generated by the internal combustion engine and the heat generated by the piezoelectric drive unit 24 when driven. End up. In this case, a disturbance based on the temperature rise of the load sensor unit 23 is included in the acquired load Faa, and the accuracy of calibration is reduced on the contrary. The number of necessary data is determined taking the above into consideration.

  In the process of S200, if the number of acquired loads Faa satisfies the required number of data, the process proceeds to S210, and if not, the process returns to S190 again.

  In S210, the load Faaav and the idle charge energy Eaaav, which are the average values of the plurality of loads Faa and idle charge energy Eaa acquired in S180, are calculated. Then, the calculated load Faaav and idling charging energy Eaaav are temporarily stored in the memory means 5a.

  In S220, a load ΔFas which is a difference between the load Fasf corresponding to the charging energy Easf serving as a reference corresponding to the starting charging energy Easav and the load Fasav, and a charging energy serving as a reference corresponding to the charging energy Eaaav during idling. A load ΔFaa, which is a difference between the load Faaf corresponding to Eaaf and the load Faaaav, is calculated (see FIG. 5).

  Here, the reference charging energy Easf and the corresponding load Fasf, and the reference charging energy Eaaf and the corresponding load Faaf are the piezoelectric drive unit at a reference temperature of 25 ° C. stored in the memory means 5a in advance. From the relationship between the reference charging energy E stored in 24 and the load F output from the load sensor unit 23 when the charging energy E is stored in the piezoelectric drive unit 24 (see the broken line in FIG. 5). It is derived.

  The charging energy Easf and the corresponding load Fasf, and the charging energy Eaaf and the corresponding load Faaf correspond to “reference charging energy” and “reference load signal” described in the claims.

  In S230, it is determined whether or not the absolute values of the load ΔFas and the load ΔFaa exceed the loads Fcs and Fca, which are predetermined determination values. In this process, if both conditions are satisfied, the process proceeds to S240, and if not satisfied, it is estimated that the deterioration of the load sensor unit 23 has not progressed, and this control flow ends.

  In the present embodiment, if both of the above two conditions are satisfied, the process proceeds to S240. However, the present invention is not limited to this. Even if either one of the conditions is satisfied, the process may proceed to S240.

  In S240, a temperature correction coefficient is calculated based on the temperature characteristics of the load sensor unit 23 shown in FIG. 6 and the outside air temperature Tat acquired in the process of S110. This process corresponds to “correction coefficient calculation means” described in the claims.

  In S250, the charging energy Easf, Eaf, the load Fasf, the load Faaf, the load Fasav, the load Faaav, the charging energy Easav at the start, the idling time acquired in the processing from S110 to S240 are stored in the memory means 5a in advance. The load sensor unit 23 is calibrated based on the charging energy Eaaav and the temperature correction coefficient (see FIG. 5). This processing corresponds to “calibration means” described in the claims. Thereby, the calibration in the load sensor unit 23 is completed, and this control flow ends. Then, the piezoelectric drive unit 24 is controlled using the load F output from the calibrated load sensor unit 23.

  In the present embodiment, when it is determined that the ECU 4 is a cold start in which the temperature of the load sensor unit 23 is relatively stable, the charging energy E and the load F are more stable than in other operating states. The load sensor unit 23 is calibrated based on the charging energy Easav, Eaaav, the load Fasav, Faav, the reference charging energy Easf, Eaaf, the reference load Fasf, Faaf, and the temperature correction coefficient in the starting operation state and the idle operation state. Is going.

  In the present embodiment, since the calibration of the load sensor unit 23 is performed under such conditions, it is possible to eliminate as much as possible the disturbance to the load sensor unit 23 that hinders improvement in calibration accuracy. Thereby, the accuracy of calibration of the load sensor unit 23 can be improved. As a result, the controllability of the piezoelectric drive unit 24 can be maintained over a long period of time, and consequently the accuracy of the fuel injection characteristics of the fuel injection valve 2 can be maintained over a long period of time.

  Since the load sensor unit 23 includes the piezoelectric layer, the load sensor unit 23 has a temperature characteristic that the amount of the output signal varies depending on the temperature even when the same load is applied. In the present embodiment, the time when the temperature of the load sensor unit 23 is relatively stable is selected as the calibration condition, but the outside air temperature Tat also changes depending on the time zone, season, or place. In the present embodiment, the temperature correction coefficient is calculated from the temperature characteristics of the load sensor unit 23 shown in FIG. 6, and the load sensor unit 23 is calibrated by taking the calculated temperature correction coefficient into consideration. According to this, it can respond also to the change of the outside temperature Tat mentioned above, and the precision of calibration improves more.

  In the present embodiment, the charging energy E is accumulated in the piezoelectric drive unit 24 from time T0, and the calibration is performed using the stable load Fa among the loads F output from the load sensor unit 23 at that time. Therefore, the calibration accuracy is improved as compared with the case where the calibration is performed using the load F having a large variation.

  It is most preferable to use a stable load Fa. However, when the number of injections per one combustion cycle is increased, the region including the stable load Fa at the time of main injection is shortened, so that it is difficult to obtain the stable load Fa. . In such a case, instead of the stable load Fa, calibration may be performed using the maximum load Fp after the valve body 19 of the control valve 18 is seated on the high-pressure side seat surface 55.

  In this embodiment, the calibration is performed using the charging energy Easf and the load Fasf acquired in the start operation state, and the charging energy Eaaf and the load Faaf acquired in the idle operation state, and therefore data when performing the calibration. You can increase the number. As a result, the accuracy of calibration of the load sensor unit 23 is improved.

  In the present embodiment, the charging energy Eas stored in the piezoelectric drive unit 24 in the starting operation state and the charging energy Eaa stored in the idle operation state are set as predetermined energy amounts. According to this, the fluctuation | variation of the charging energy to accumulate can be made small and can be stabilized. For this reason, stable loads Fas and Faa can be acquired.

(Second Embodiment)
The second embodiment of the present invention is a modification of the first embodiment. In the second embodiment, the amount of charging energy stored in the piezoelectric drive unit 24 during the start-up operation of the internal combustion engine is the same as the charging energy stored in the idling operation state.

  FIG. 7 is a control flow from the start to the stop of the internal combustion engine in the second embodiment. This control flow is started when the ECU 4 detects that an ignition switch (not shown) is turned on.

  As shown in FIG. 7, in S310, a drive signal is output to a drive circuit (not shown) of a starter (cell motor), and the starter is activated. As a result, the crankshaft of the internal combustion engine rotates.

  Then, in S320, it is determined that the starter is operating, so that the operation state is determined to be a start operation state, and the drive circuit 3 includes an idle charge control signal and an idle discharge control signal. A control signal is output. When the drive circuit 3 receives this control signal, it accumulates idling charging energy in the piezoelectric drive unit 24 of the predetermined fuel injection valve 2. In the present embodiment, the amount of charging energy during idling is determined in advance.

  In S330, it is determined whether the starter has stopped. Through this process, it can be determined that the internal combustion engine has escaped from the starting operation state and has shifted to a self-sustained operation in which fuel burns in the combustion chamber. In the present embodiment, the starter stops when it shifts to a self-sustained operation based on crankshaft rotation fluctuation, torque fluctuation, and the like. In this embodiment, it is determined whether or not the internal combustion engine has shifted to a self-sustained operation by detecting the operation state of the starter, but has shifted to a self-sustained operation by detecting a crankshaft rotation fluctuation or torque fluctuation. It may be determined whether or not.

  If it is determined in S330 that the starter is still operating, the process returns to S320, and the start time control signal is output to the drive circuit 3 again. If it is determined in S330 that the starter has stopped, the process proceeds to S40.

  In S340, assuming that the operation state has shifted to the idle operation state, the idle control signal output in the start operation state is output to the drive circuit 3. When the drive circuit 3 receives this control signal, it accumulates idling charging energy in the piezoelectric drive unit 24 of the predetermined fuel injection valve 2.

  In S350, it is determined whether or not the accelerator pedal is depressed from the information on the accelerator pedal depression amount input to the ECU 4. By executing this process, it is possible to determine whether or not the vehicle has escaped from the idle operation state and has shifted to the normal operation state according to the accelerator pedal depression amount. In the present embodiment, it is determined whether or not the engine is in the idle maneuvering state based on the accelerator pedal depression amount, but may be determined based on the internal combustion engine speed. Further, if the vehicle model is equipped with a throttle valve device, the determination may be made by receiving a signal from an idle switch provided in the throttle valve device.

  If it is determined in S350 that the accelerator pedal is not depressed, the process returns to S340, and the idle control signal is output to the drive circuit 3 again. If it is determined in S350 that the accelerator pedal has been depressed, the process proceeds to S360.

  In S360, a normal control signal including a normal charge control signal and a normal discharge control signal is output to the drive circuit 3 in order to control the internal combustion engine in accordance with the amount of depression of the accelerator pedal.

  In S370, it is determined whether or not the ignition switch is off. By executing this process, it can be determined whether or not the internal combustion engine has been stopped. If it is determined in S370 that the ignition switch is off, the control flow ends. If it is determined that the ignition switch is on, the process returns to S60, and the normal time control signal is continuously output to the drive circuit 3.

  Next, calibration of the load sensor unit 23 in the present embodiment will be described with reference to FIGS. FIG. 8 is a control flow when the load sensor unit 23 is calibrated. FIG. 9 is a graph showing the relationship between the charging energy supplied to each piezoelectric drive unit 24 at the time of factory shipment and after deterioration (before calibration) and the load at that time.

  This control flow is started when the ECU 4 detects that the ignition switch is turned on.

  As shown in FIG. 8, in S410, the outside air temperature Tat is acquired based on the output signal from the outside air temperature sensor 60 (see FIG. 1). Subsequently, in S420, based on the output signal from the cooling water temperature sensor 61 (see FIG. 1) for detecting the cooling water temperature of the internal combustion engine, the lubricating oil temperature sensor 62 (for detecting the lubricating oil temperature of the internal combustion engine). The oil temperature To is acquired based on the output signal from (see FIG. 1). Furthermore, in S430, it is determined whether or not the acquired water temperature Tw and oil temperature To are substantially the same as the outside air temperature Tat. If it is determined that the water temperature Tw and the oil temperature To are substantially the same as the outside air temperature Tat, the process proceeds to S440. Otherwise, the load sensor unit 23 receives the heat of the internal combustion engine and performs an appropriate calibration. This control flow ends. In the present embodiment, the processing in S420 corresponds to “engine temperature acquisition means” recited in the claims.

  By executing the process of S430, it is possible to determine the cold start of the internal combustion engine. In the present embodiment, the processing in S430 corresponds to “cold start determination means” recited in the claims. In the present embodiment, it is determined whether the internal combustion engine is cold-started by comparing both the water temperature Tw and the oil temperature To with the outside air temperature Tat, but only the water temperature Tw and the oil temperature To The cold start may be determined only from the above. In the present embodiment, the cold start is determined based on whether or not the acquired water temperature Tw and oil temperature To are substantially the same as the outside air temperature Tat. This is a result of adding detection errors of the cooling water temperature sensor 61, the lubricating oil temperature sensor 62, and the outside air temperature sensor 60, and the water temperature Tw or the oil temperature To is the outside air temperature Tat depending on these detection errors. What is necessary is just to determine the range which can be considered as appropriate.

  In S440, it is determined whether or not an idling charge control signal is output to the drive circuit 3. If it is determined that the idling charge control signal is output to the drive circuit 3, the process proceeds to S450. If it is determined that the idling charge control signal is not output, the idling charge control signal is output. The process of S440 is repeatedly executed until

  In S450, the load Fas of the main injection out of a plurality of injections performed during one combustion cycle, and the idling charging energy Eaa at that time are acquired. The load Faa is a load F corresponding to the load Fa shown in FIG. 2, and is a load F when the charging energy Eaa during idling is accumulated in the piezoelectric driving unit 24. The load Faa and idling charge energy Eaa acquired in S450 are temporarily stored in the memory means 5a provided in the ECU 4. In the present embodiment, the processing in S450 corresponds to “acquiring means” recited in the claims.

  In S460, it is determined whether or not the number of acquired loads Faa satisfies the required number of data. In the present embodiment, the number of necessary data is about n = 10. The more data that is acquired, the higher the accuracy of calibration. However, since the internal combustion engine continues to operate even during the acquisition of the load Faa, the temperature of the load sensor unit 23 rises due to the heat generated by the internal combustion engine and the heat generated by the piezoelectric drive unit 24 when driven. End up. In this case, a disturbance based on the temperature rise of the load sensor unit 23 is included in the acquired load Faa, and the accuracy of calibration is reduced on the contrary. The number of necessary data is determined taking the above into consideration.

  In the process of S460, if the number of acquired loads Faa satisfies the required number of data, the process proceeds to S470, and if not, the process returns to S450 again.

  In S470, the load Faaav and the idle charge energy Eaaav, which are the average values of the load Faa and the idle charge energy Eaa acquired in S450, are calculated. Then, the calculated load Faaav and idling charging energy Eaaav are temporarily stored in the memory means 5a.

  In S480, a load ΔFaa, which is a difference between the load Faaf corresponding to the reference charge energy Eaaaf corresponding to the idle charge energy Eaaav and the load Faaaav, is calculated (see FIG. 9).

  Here, the reference charging energy Eaaaf and the corresponding load Faaf are the reference charging energy E stored in the piezoelectric drive unit 24 at the reference temperature 25 ° C. stored in the memory means 5a in advance and the charging energy Eaf. This is derived from the relationship with the load F output from the load sensor unit 23 when the energy E is accumulated in the piezoelectric drive unit 24 (see the broken line in FIG. 9). The charging energy Eaaf and the corresponding load Faaf correspond to “reference charging energy” and “reference load signal” described in the claims.

  In S490, it is determined whether or not the absolute value of the load ΔFaa exceeds a load Fca that is a predetermined determination value. In this process, if the condition is satisfied, the process proceeds to S500, and if not satisfied, it is estimated that the deterioration of the load sensor unit 23 has not progressed, and the control flow ends.

  In S500, a temperature correction coefficient is calculated based on the temperature characteristics of the load sensor unit 23 shown in FIG. 5 and the outside air temperature Tat acquired in the process of S410. This process corresponds to “correction coefficient calculation means” described in the claims.

  In S510, based on the charging energy Eaaaf, the load Faaf, the load Faaaav acquired in the processing from S410 to S500, the idling charging energy Eaaav, and the temperature correction coefficient, which are stored in the memory unit 5a in advance, the load sensor unit 23 is used. Is performed (see FIG. 9). This processing corresponds to “calibration means” described in the claims. Thereby, the calibration in the load sensor unit 23 is completed, and this control flow ends. Then, the piezoelectric drive unit 24 is controlled using the load F output from the calibrated load sensor unit 23.

  In the present embodiment, when it is determined that the ECU 4 is a cold start in which the temperature of the load sensor unit 23 is relatively stable, the charging energy E and the load F are more stable than in other operating states. The load sensor unit 23 is calibrated based on the charging energy Eaaav, the load Faaaav, the reference charging energy Eaaaf, the reference load Faaf, and the temperature correction coefficient in the start operation state and the idle operation state.

  In the present embodiment, since the calibration of the load sensor unit 23 is performed under such conditions, it is possible to eliminate as much as possible the disturbance to the load sensor unit 23 that hinders improvement in calibration accuracy. Thereby, the accuracy of calibration of the load sensor unit 23 can be improved. As a result, the controllability of the piezoelectric drive unit 24 can be maintained over a long period of time, and consequently the accuracy of the fuel injection characteristics of the fuel injection valve 2 can be maintained over a long period of time.

  Here, there is a fact that the exhaust gas regulation in the idle operation state is stricter than in the high load operation state. In the idle operation state, the fuel injection amount injected from the fuel injection valve 2 is very small, and the ratio of the variation in the injection amount to the required injection amount in this operation state is higher than in the high load operation state. For this reason, it is necessary to improve the accuracy of the fuel injection characteristics in this operating state. In contrast, in the present embodiment, the load sensor unit 23 is calibrated based on the idling charge energy Eaaav and the load Faaav. Therefore, at least the accuracy of the calibration of the load sensor unit 23 in the idle operation state is improved. Can do.

  In the present embodiment, the amount of charging energy stored in the piezoelectric drive unit 24 is set to the amount of charging energy during idling regardless of the start operation state and the idle operation state. Therefore, the control flow shown in FIG. 8 may be performed while the starter is operating, or may be performed after the starter is stopped.

(Third embodiment)
The third embodiment of the present invention is a modification of the fuel injection valve 2 in the first embodiment. In the third embodiment, the mechanism for controlling the valve closing drive and the valve opening drive of the needle 212 is different from that of the fuel injection valve 2 in the first embodiment.

  FIG. 10 shows a cross section of the fuel injection valve 200 in the third embodiment.

  The fuel injection valve 200 includes a nozzle 211, a cylinder 217, a fixed piston 220, an actuator portion 230, and the like, and these components are accommodated in a body 240 formed in a rod shape.

  The body 240 includes a fuel inlet 241 into which high-pressure fuel from the pressure accumulator is introduced. A housing portion 242 is formed on one end side of the body 240 in the axial direction. The accommodating portion 242 accommodates a nozzle 211 that controls fuel injection and non-injection.

  The nozzle 211 has a needle 212 and a nozzle spring 216. The needle 212 is slidably held in the housing portion 242. An injection hole 243 that communicates with the fuel inlet 241 via the high-pressure fuel passage 245 is formed at one axial end side of the housing 242.

  A valve seat 244 on which the seat portion 213 formed on the needle 212 is seated is formed on the fuel inlet portion 241 side of the nozzle hole 243. When the seat portion 213 is seated on the valve seat 244, the flow of fuel to the injection hole 243 is closed, and fuel injection from the injection hole 243 is stopped. When the seat portion 213 is separated from the valve seat 244, the fuel flow to the injection hole 243 is allowed, and the fuel is injected from the injection hole 243.

  A piston portion 214 is formed at the end of the needle 212 opposite to the seat portion 213. The piston part 214 is slidably inserted into the cylinder 217. A flange portion 215 is formed between the seat portion 213 and the piston portion 214 of the needle 212, and a nozzle spring 216 is provided between the flange portion 15 and the cylinder 217. The nozzle spring 216 urges the needle 212 in the direction in which the seat portion 213 is seated on the valve seat 244, that is, in the valve closing direction.

  The actuator portion 230 is accommodated on the other axial end side of the accommodation portion 242. The actuator unit 230 includes the piezoelectric actuator 22 and a push plate 231 that transmits the displacement from the piezoelectric actuator 22 to the cylinder 217. When the piezoelectric drive unit 24 of the piezoelectric actuator 22 expands and contracts, the cylinder 217 is driven via the push plate 231.

  The cylinder 217 is a stepped cylindrical member having a stepped portion on the inner peripheral surface, and a first cylinder hole 218 is formed on one side of the stepped portion, and a first cylinder is formed on the other side of the stepped portion. A second cylinder hole 219 having a diameter larger than that of the hole 218 is formed. The cylinder 217 is accommodated in the accommodating portion 242 such that the first and second cylinder holes 218 and 219 are arranged along the axial direction of the body 240. The first cylinder hole 218 is disposed closer to the injection hole 243 than the second cylinder hole 219.

  A fixed piston 220 is slidably inserted into the second cylinder hole 219. The fixed piston 220 includes a fixed piston portion 221 and a flange portion 222 that protrudes radially outward from the fixed piston portion 221. Only the fixed piston portion 221 is inserted into the second cylinder hole 219.

  A control chamber 246 is formed by the cylinder 217, the fixed piston portion 221, and the piston portion 214 between the fixed piston portion 221 and the piston portion 214 of the needle 212. The high-pressure fuel that has once flowed into the accommodating portion 242 flows into the control chamber 246 via the clearance between the first cylinder hole 218 and the piston portion 214 and between the second cylinder hole 219 and the fixed piston portion 221. Yes.

  FIG. 11 is a XI view of the fixed piston 220 viewed from the nozzle hole 243 side. As shown in this figure, the flange portion 222 of the fixed piston 220 is divided into three pieces along the circumferential direction, and a notch 223 is formed between the adjacent flange portions 222. As shown in FIG. 10, the flange portion 222 is sandwiched between a spacer 234 supported on the inner wall of the housing portion 242 and a fixed spring 235 supported on the inner wall of the housing portion 242, whereby the fixed piston 220 is Fixed to the body 240.

  FIG. 12A is a front view of the push plate 231, and FIG. 12B is a bottom view of the push plate 231. As shown in FIG. 12, the push plate 231 includes a columnar disk portion 232 and three columnar leg portions 233 protruding in the axial direction from one end surface of the disk portion 232.

  These leg portions 233 are provided along the circumferential direction at positions where the leg portions 233 are inserted into the notches 223 when the push plate 231 and the fixed piston 220 are combined (see FIG. 11). As shown in FIG. 10, the push plate 231 is accommodated in the accommodating portion 242 such that the disc portion 232 abuts on the piezoelectric drive portion 24 of the piezoelectric actuator 22 and the leg portion 233 abuts on the cylinder 217.

  In the present embodiment, the nozzle 211, the cylinder 217, the fixed piston 220, and the spacer 234 correspond to the “injection functional component” recited in the claims.

  Next, the operation of the fuel injection valve 200 will be described. When the piezoelectric drive unit 24 of the piezoelectric actuator 22 is not extended, the cylinder 217 is moved to the piezoelectric actuator 22 side by the urging force of the nozzle spring 216. At this time, high-pressure fuel in the accommodating portion 242 flows into the control chamber 246 through the clearance between the first cylinder hole 218 and the piston portion 214 and the clearance between the second cylinder hole 219 and the fixed piston portion 221. The fuel pressures in the control chamber 246 and the accommodating portion 242 are equal.

  In this state, the needle 212 is closed by a force in the valve closing direction generated by the needle 212 due to the fuel pressure in the control chamber 246 acting on the piston portion 214 and a force generated by the urging force of the nozzle spring 216. The sum of the forces in the valve direction is larger than the force in the valve opening direction generated in the needle 212 due to the high pressure fuel in the accommodating portion 242 acting on the needle 212. For this reason, the seat part 213 of the needle 212 is seated on the valve seat 244, and the fuel injection from the injection hole 243 stops (state of FIG. 10).

  When the piezoelectric drive unit 24 extends, the cylinder 217 moves toward the nozzle hole 243 as the piezoelectric drive unit 24 extends. Since the diameter of the first cylinder hole 218 is smaller than that of the second cylinder hole 219, the volume in the control chamber 246 increases when the cylinder 217 moves to the injection hole 243 side. As a result, the fuel pressure in the control chamber 246 decreases as the cylinder 217 moves. Thereby, the total force in the valve closing direction generated in the needle 212 becomes smaller than the force in the valve opening direction, the needle 212 moves in the valve opening direction, and the seat portion 213 is separated from the valve seat 244, Fuel is injected from the injection hole 243.

  Thereafter, when the piezoelectric drive unit 24 contracts again, the cylinder 217 moves to the piezoelectric actuator 22 side by the urging force of the nozzle spring 216, and the volume of the control chamber 246 is reduced. Thereby, the fuel pressure in the control chamber 246 increases, and the total force in the valve closing direction becomes larger than the force in the valve opening direction. Accordingly, the seat portion 213 is seated on the valve seat 244, and fuel injection from the injection hole 243 is stopped.

  Also in this embodiment, in accordance with the control flow shown in FIG. 4, similarly to the first embodiment, detection is performed by the load sensor unit 23 when the starting charging energy Eas corresponding to the starting operation state is accumulated in the piezoelectric driving unit 24. The load Fas detected, the load Faa detected by the load sensor 23 when charging energy Eaa during idling according to the idle operation state is accumulated in the piezoelectric drive unit 24, and charging at the time of starting which becomes a reference stored in advance The load sensor unit 23 is calibrated based on the energy Easf and the load Fasf, the reference charging energy Eaaf and the load Faaf during idling, and a temperature correction coefficient.

  Thereby, the accuracy of calibration of the load sensor unit 23 can be improved. As a result, the controllability of the piezoelectric drive unit 24 can be maintained over a long period of time, and consequently the accuracy of the fuel injection characteristics of the fuel injection valve 200 can be maintained over a long period of time. Moreover, you may calibrate the load sensor part 23 according to the control flow shown in FIG. 8 of 2nd Embodiment.

It is sectional drawing which shows the whole structure of the fuel supply apparatus containing the fuel-injection control apparatus by 1st Embodiment of this invention. It is a time chart which shows the operating state of the piezoelectric drive part in a piezoelectric actuator, and the valve body of a control valve. It is a control flow from the start start of an internal combustion engine to a stop. It is a control flow at the time of calibrating a load sensor part. It is a graph which shows the relationship between the charging energy accumulate | stored in a piezoelectric drive part, and the load at that time. It is a temperature characteristic figure of a load sensor part. It is a control flow from the start start of the internal combustion engine in 2nd Embodiment to a stop. It is a control flow at the time of calibrating a load sensor part. It is a graph which shows the relationship between the charging energy accumulate | stored in a piezoelectric drive part, and the load at that time. It is sectional drawing which shows the structure of the fuel injection valve by 3rd Embodiment. FIG. 11 is a XI view of the fixed piston of FIG. 10. (A) is a front view of the push plate of FIG. 10, (b) is a bottom view of the push plate.

Explanation of symbols

  1 fuel supply device, 2 fuel injection valve (fuel injection device), 3 drive circuit, 4 electronic control device (ECU, fuel injection control device), 5 MPU, 5a memory means (storage means), 8 return path, 9 back pressure valve DESCRIPTION OF SYMBOLS 10 Fuel tank, 11 Nozzle (injection functional component), 12 Needle, 18 Control valve (injection functional component), 19 Valve body, 21 Actuator part, 22 Piezoelectric actuator, 23 Load sensor part, 24 Piezoelectric drive part, 30 Displacement transmission Part (injection function part), 31 actuator cylinder, 32 first piston, 33 second piston, 34 liquid chamber, 40 body, 41 fuel inlet part, 42 fuel outlet part, 43 housing part, 44 injection hole, 45 valve seat, 46 High-pressure fuel passage, 47 High-pressure communication passage, 48 Low-pressure fuel passage, 49 Low-pressure communication passage, 50 Communication passage, 52 Control room, 3 the valve chamber, the low-pressure side seat surface 54, 55 high-pressure side seat surface, 60 outside air temperature sensor, 61 a cooling water temperature sensor, 62 lubricating oil temperature sensor

Claims (8)

A body mounted on the internal combustion engine and having injection holes for injecting fuel introduced into the combustion chamber of the internal combustion engine;
An injection function part including a valve member housed in the body and intermittently injecting fuel from the injection hole;
A piezoelectric body housed in the body, extending by storing charging energy and contracting by discharging the stored charging energy, and driving the valve by driving at least one of the jetting functional components A piezoelectric drive unit for controlling the drive of the member;
A fuel that is housed in the body and includes a piezoelectric body that outputs a load signal corresponding to a load acting on the piezoelectric driving unit when the charging energy is stored in the piezoelectric driving unit. A fuel injection control device that is provided in an injection device and controls the piezoelectric drive unit based on the load signal from the load sensor unit,
Cold start determination means for determining cold start of the internal combustion engine;
The charge energy stored in the piezoelectric drive unit during at least one of a start operation state from the start of the internal combustion engine to a self-sustaining operation or a no-load operation state, and the charge energy stored in the piezoelectric drive Acquiring means for acquiring a load signal output from the load sensor unit when accumulated in the unit;
Storage means for storing reference charging energy and a reference load signal output from the load sensor unit when the reference charging energy is accumulated in the piezoelectric driving unit;
When the cold start determination means determines that the internal combustion engine is cold start, based on the charge energy and the load signal acquired by the acquisition means, and the reference charge energy and the reference load signal, A fuel injection control device comprising calibration means for calibrating the load sensor unit. Correction coefficient calculation means for calculating a temperature correction coefficient based on the temperature of the load sensor unit,
2. The fuel injection control apparatus according to claim 1, wherein the calibration unit calibrates the load sensor unit in consideration of the temperature correction coefficient calculated by the correction coefficient calculation unit.   The charge energy accumulated in the piezoelectric drive unit in the start operation state and the no-load operation state is a predetermined energy amount corresponding to each operation state. A fuel injection control device according to claim 1. The acquisition means includes a predetermined starting charging energy corresponding to the starting operating state, a predetermined no-load charging energy corresponding to the no-load operating state, and the starting charging energy to the piezoelectric driving unit. And obtaining each load signal output from the load sensor unit when the no-load charging energy is accumulated,
The said calibration means calibrates the said load sensor part based on the said charging energy at the time of starting and the said charging energy at the time of no load, and each said load signal which the said acquisition means acquired. A fuel injection control device according to claim 1. The acquisition means outputs a predetermined no-load charging energy corresponding to the no-load operation state and the load sensor unit when the no-load charging energy is accumulated in the piezoelectric drive unit. Get the load signal
4. The fuel injection control device according to claim 3, wherein the calibration unit calibrates the load sensor unit based on the no-load charging energy and the load signal acquired by the acquisition unit.   The load signal used when the calibration means calibrates the load sensor unit is the amount of change per unit time that is output until the charging energy is released from the maximum load signal indicating the largest value. The fuel injection control device according to any one of claims 1 to 5, wherein is a smallest stable load signal. The cold start determination means includes an outside air temperature acquisition means for acquiring an outside air temperature, and an engine temperature acquisition means for acquiring an engine temperature of the internal combustion engine,
The fuel injection control device according to any one of claims 1 to 6, wherein the cold start is determined by comparing the acquired outside air temperature and the engine temperature.   8. The fuel injection control device according to claim 7, wherein the engine temperature acquisition means acquires a coolant temperature for cooling the internal combustion engine or a lubricating oil temperature used for lubrication of the internal combustion engine.

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