JP5294510B2 - Control device and control method for fuel injection device - Google Patents

Description

  The present invention relates to a control device and a control method for a fuel injection device. In particular, the present invention relates to a control device and a control method for a fuel injection device including a common rail that is connected to a plurality of fuel injection valves and stores high-pressure fuel.

  Conventionally, as a device for supplying fuel to an internal combustion engine such as a diesel engine, a state in which a plurality of fuel injection valves are connected and a common rail for storing high-pressure fuel is provided, and high-pressure fuel is supplied to each fuel injection valve A pressure accumulating fuel injection device that enables precise fuel injection control by controlling the opening and closing of the fuel injection valve is used.

  This accumulator fuel injection device is composed mainly of a fuel tank, a low-pressure pump, a high-pressure pump, a common rail, and a fuel injection valve. The fuel in the fuel tank is pumped by the low-pressure pump. And is pressurized by a high-pressure pump and pumped to the common rail, and high-pressure fuel is supplied to each fuel injection valve. In this state, the valve opening time and valve opening timing of the fuel injection valve are controlled by energization control of the fuel injection valve, and various fuel injection patterns can be realized.

  In such an accumulator fuel injection device, for the purpose of reducing noise during operation of the internal combustion engine, fuel injection to the internal combustion engine is divided into a plurality of times per one rotation cycle, and auxiliary injection ( May be referred to as pilot injection). In addition, in the accumulator type fuel injection device, since the rail pressure pulsates after each injection by the fuel injection valve, the effect of pressure fluctuations on the amount of fuel to be injected is reduced when fuel injection is performed in multiple times. A control method and control apparatus for an internal combustion engine as described above have been proposed (see, for example, Patent Documents 1 and 2).

  However, when the internal combustion engine is in the rated operating range, the rotational speed of the internal combustion engine is relatively high and the influence on the noise vibration is relatively small, so that the auxiliary injection is performed without dividing the fuel injection into the internal combustion engine into multiple times. In many cases, only main injection is performed without being performed.

Japanese Patent Laid-Open No. 10-266888 (full text, full figure) Special table 2004-504528 gazette (the whole sentence, all figure)

By the way, the amount of fuel injected from the fuel injection valve is adjusted by adjusting the valve opening time during which the nozzle needle that closes the injection hole is lifted. It depends on the shape of the injection hole provided in the body. The shape of the nozzle body injection hole is designed mainly considering the hydraulic flow rate.
On the other hand, since the state of the spray of fuel to be injected is determined by the size of the injection hole, in order to more efficiently form a good fuel spray state as the regulation value of the exhaust gas regulation becomes stricter, The injection hole provided in the nozzle body is designed to be small.

  However, if the injection hole of the fuel injection valve becomes excessively small, the injection time when injecting a predetermined amount of fuel becomes relatively long, and the exhaust temperature is high when the internal combustion engine is in the rated operating range. There is a risk that the exhaust temperature may exceed the allowable temperature of the exhaust system of the internal combustion engine in an operation region that tends to occur. Then, the injection time of the main injection must be set short, but if the injection time is made shorter than the original injection time of the main injection in the rated operation region where only the main injection is performed, the required internal combustion The engine output cannot be secured.

  Therefore, the inventor of the present invention diligently tried to cause pulsation in the pressure of the high-pressure fuel sent to the fuel injection valve before the main injection to the internal combustion engine, and when the pressure fluctuation satisfies a predetermined condition, The present invention has been completed by finding that the above-mentioned problems can be solved by controlling the fuel injection valve so that the above is performed. That is, according to the present invention, although the injection hole of the fuel injection valve is relatively small, the injection time of the main injection is shortened without reducing the fuel injection amount in the rated operation region of the internal combustion engine. It is an object of the present invention to provide a control device and a control method for a fuel injection device capable of suppressing an increase in exhaust gas temperature while maintaining an engine output.

According to the present invention, fuel is injected into the internal combustion engine using the fuel injection valve in which the injection hole is opened by releasing the back pressure acting on the rear end side of the nozzle needle that closes the injection hole. In the control device of the fuel injection device for controlling the fuel injection device that supplies, when the internal combustion engine is in the rated operation region, and a rated region determination unit that determines whether the internal combustion engine is in the rated operation region, before performing the main injection to the internal combustion engine, a preliminary back pressure controller for performing ineffective control of fuel injection from the injection hole of the fuel injection valve is not performed as a back pressure relief control of the minor, the back pressure relief control of the minor The main injection control unit that performs main injection when the pressure rises and the pressure amplitude is positive, and the high pressure that is sent to the fuel injection valve Detect fuel temperature Both the control device of the fuel injection system, characterized in that it comprises a preliminary backpressure timing correction unit for correcting the timing of performing in correspondence with the temperature of the high-pressure fuel back pressure relief traces control, the is provided, above Problem can be solved.

Another aspect of the present invention provides an internal combustion engine using a fuel injection valve in which a fuel injection is performed by releasing a back pressure by releasing a back pressure acting on the rear end side of a nozzle needle that closes the injection hole. In a control device for a fuel injection device for controlling a fuel injection device that supplies and injects fuel, a rated region determination unit that determines whether or not the internal combustion engine is in a rated operation region, and the internal combustion engine in a rated operation region In some cases, before performing the main injection to the internal combustion engine, a preliminary back pressure control unit that performs idle driving control in which fuel injection is not performed from the injection hole of the fuel injection valve as a small amount of back pressure relief control, From the internal combustion engine, a main injection control unit that performs main injection when the pressure rises and the amplitude of the pressure is positive with respect to the pulsation of the pressure of the high-pressure fuel sent to the fuel injection valve generated by the back pressure relief control Exhaust temperature is If it is more than the threshold value, the control apparatus for a fuel injection system, characterized in that it comprises an exhaust temperature determination unit to perform the back pressure relief control of the minor in rated operation range of the internal combustion engine, a.

Another aspect of the present invention provides an internal combustion engine using a fuel injection valve in which a fuel injection is performed by releasing a back pressure by releasing a back pressure acting on the rear end side of a nozzle needle that closes the injection hole. In the control method of the fuel injection device for performing the fuel injection supply, the fuel injection valve is controlled by performing a small amount of back pressure relief control before performing the main injection to the internal combustion engine in a state where the internal combustion engine is in the rated operation region. Pulsation is generated in the pressure of the high-pressure fuel to be sent, and main injection is performed when the pressure rises and the pressure amplitude is positive. A small amount of back pressure relief control is performed from the injection hole of the fuel injection valve. This is a control method for a fuel injection device, wherein the control is a blank injection control in which injection is not performed, and the timing for performing the blank shot control is corrected in accordance with the temperature of the high-pressure fuel.

Another aspect of the present invention provides an internal combustion engine using a fuel injection valve in which a fuel injection is performed by releasing a back pressure by releasing a back pressure acting on the rear end side of a nozzle needle that closes the injection hole. In the control method of the fuel injection device for performing the fuel injection supply, the fuel injection valve is controlled by performing a small amount of back pressure relief control before performing the main injection to the internal combustion engine in a state where the internal combustion engine is in the rated operation region. Pulsation is generated in the pressure of the high-pressure fuel to be sent, and main injection is performed when the pressure rises and the pressure amplitude is positive. A small amount of back pressure relief control is performed from the injection hole of the fuel injection valve. A fuel injection device that performs idling control in a rated operation region of an internal combustion engine when the exhaust temperature discharged from the internal combustion engine is equal to or higher than a predetermined threshold value. This is a control method.

  According to the control device and the control method for the fuel injection device of the present invention, when the internal combustion engine is in the rated operation region, a small amount of back pressure is released before the main injection to the internal combustion engine is performed, and the fuel injection valve After the pulsation of the pressure of the high-pressure fuel to be sent occurs, main injection is performed when the pressure of the high-pressure fuel rises and when the pressure amplitude is positive. Therefore, even when the injection hole of the fuel injection valve is designed to be relatively small, the injection time of the main injection is shortened without reducing the amount of fuel injected into the internal combustion engine, and the output of the internal combustion engine is maintained. In addition, an increase in exhaust temperature is suppressed. As a result, a smaller injection hole can be selected and the fuel is atomized, so that it is easy to cope with exhaust gas regulations despite the high output of the internal combustion engine.

  Further, in the control device for the fuel injection device of the present invention, the minute amount of back pressure relief control performed before the main injection, which is performed by the preliminary back pressure control unit, is the idle driving control. No fuel is supplied to the internal combustion engine during the escape control. Therefore, there is no possibility that a small amount of back pressure relief control will affect the combustion characteristics of the fuel in the internal combustion engine.

  Further, in the control device for the fuel injection device of the present invention, when the main injection control section first satisfies a predetermined condition after the pressure of the high-pressure fuel sent to the fuel injection valve by a small amount of back pressure relief control is reduced. By performing the main injection, the peak value of the pressure pulsation generated in the high-pressure fuel sent to the fuel injection valve is suppressed. Therefore, the load applied to the common rail, the high-pressure fuel passage connecting the common rail and the fuel injection valve, the fuel injection valve, and the like is reduced.

  Further, in the control device for the fuel injection device of the present invention, a preliminary back pressure control timing correction unit that corrects a timing for performing a minute amount of back pressure relief control based on the temperature of the high pressure fuel is provided, so that the temperature of the high pressure fuel is increased. Considering the shift in the frequency of the pressure pulsation of the high-pressure fuel due to the influence of the above, a small amount of back pressure relief control is performed so that the main injection is performed at a time when a predetermined condition is satisfied.

  Further, in the control device for the fuel injection device according to the present invention, an exhaust temperature determination unit that performs a very small amount of back pressure relief control in a situation where the exhaust temperature is likely to exceed a predetermined threshold is provided. At a time when it is not necessary to decrease the amount of back pressure relief, a very small amount of back pressure relief control is not performed. Therefore, the increase in the number of injections in a state where the rail pressure is high is suppressed, and the pressure pulsation of the high-pressure fuel sent to the fuel injection valve is suppressed. Therefore, the high-pressure fuel passage connecting the common rail and the fuel injection valve, the fuel injection valve The load on is reduced.

It is a figure which shows the structural example of the fuel-injection apparatus provided with the control apparatus of the fuel-injection apparatus concerning embodiment of this invention. It is a figure which shows the structural example of a piezo-type fuel injection valve. It is a block diagram for demonstrating the structural example of the control apparatus of a fuel-injection apparatus. It is a figure which shows the flow for demonstrating the control method of the fuel-injection apparatus concerning embodiment of this invention. It is a figure which shows the time chart for demonstrating the energization amount of the fuel injection valve at the time of implementing the control method of a fuel-injection apparatus, the pressure in a high pressure fuel path, and fuel injection amount.

  Embodiments relating to a control device and a control method for a fuel injection device according to the present invention will be specifically described below with reference to the drawings. However, this embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention. In addition, what attached | subjected the same code | symbol in each figure has shown the same member, and description is abbreviate | omitted suitably.

1. Basic Configuration of Fuel Injection Device FIG. 1 shows a schematic configuration of a fuel injection device 50 provided with a control device (ECU: Electronic Control Unit) 40 of the fuel injection device of the present embodiment.
A fuel injection device 50 shown in FIG. 1 is a fuel injection device that injects fuel into a cylinder of a diesel engine of a vehicle, and includes a fuel tank 1, a low-pressure feed pump 2, a high-pressure pump 5, a common rail 10, A fuel injection valve 13 and the like are provided as main components. Each component is connected by a fuel passage. In FIG. 1, the high pressure fuel passage 37 is indicated by a thick line, the low pressure fuel passages 18a to 18c are indicated by thin lines, and the fuel return passages 30a to 30c are indicated by broken lines. ing.

(1) Low pressure feed pump The low pressure feed pump 2 supplies low pressure fuel to the pressurizing chamber 5a of the high pressure pump 5 through the low pressure fuel passages 18a to 18c. A low-pressure feed pump 2 shown in FIG. 1 is an in-tank electromagnetic low-pressure pump provided in a fuel tank 1 in which fuel is stored. The low-pressure feed pump 2 is driven by an electric current supplied from a battery. Pumped. A prefilter 3 is interposed in the fuel suction port of the low-pressure feed pump 2, and when foreign matter is mixed in the fuel in the fuel tank 1, the foreign matter is collected so as not to be sucked into the low-pressure feed pump 2. Is done. Further, a main filter 4 is provided in the middle of the low-pressure fuel passages 18 a and 18 b connecting the fuel tank 1 and the high-pressure pump 5, and foreign matter in the fuel is also collected by the main filter 4. It is designed not to flow into.
However, the low pressure feed pump 2 may be provided in the middle of the low pressure fuel passages 18 a to 18 b connecting the fuel tank 1 and the high pressure pump 5, or a pump assembled integrally with the high pressure pump 5. It may be configured as a unit.

(2) High-pressure pump The high-pressure pump 5 is pressurized by the low-pressure feed pump 2 and pressurized by the plunger 7 with the low-pressure fuel introduced into the pressurizing chamber 5a via the fuel intake valve 6, and the fuel discharge valve 9 and the high-pressure fuel passage The high pressure fuel pressurized through 37 is pumped to the common rail 10. In the example of the fuel injection device 50 shown in FIG. 1, the low pressure fuel sent into the high pressure pump 5 through the low pressure fuel passages 18a and 18b once flows into the cam chamber 16 in which the cam 15 is accommodated. Further, it is sent to the pressurizing chamber 5a through the low-pressure fuel passage 18c.

  A flow rate control valve 8 is provided in the middle of the low pressure fuel passage 18c connecting the cam chamber 16 and the pressurizing chamber 5a, and the flow rate of the low pressure fuel is adjusted according to the required common rail pressure and the required injection amount. It is sent to the pressurizing chamber 5a. As this flow control valve 8, for example, an electromagnetic proportional flow control valve is used. By adjusting the flow rate of the low-pressure fuel supplied to the pressurizing chamber 5a by the flow rate control valve 8, the pumping amount of the high-pressure fuel from the high-pressure pump 5 to the common rail 10 is adjusted, thereby suppressing the driving torque of the high-pressure pump 5. It is done.

  Further, on the upstream side of the flow rate control valve 8, there is provided a pressure adjustment valve 14 that is branched and connected from the low pressure fuel flow path 18 c and is arranged in parallel with the flow rate control valve 8. Is further connected to a fuel return path 30 a that leads to the fuel tank 1. This pressure adjustment valve 14 is the difference between the differential pressure before and after, that is, the pressure in the low pressure fuel passages 18 a to 18 c and the cam chamber 16, and the pressure in the fuel return path 30 a on the fuel tank 1 side from the pressure adjustment valve 14. An overflow valve is used that opens when the value exceeds a predetermined value. Therefore, in a state where the low pressure fuel is being pumped by the low pressure feed pump 2, the pressures in the low pressure fuel flow paths 18a to 18c and the cam chamber 16 are larger than the pressure in the fuel return path 30a by a predetermined differential pressure. To be maintained.

(3) Common rail The common rail 10 accumulates high-pressure fuel pumped from the high-pressure pump 5 and supplies high-pressure fuel to the plurality of fuel injection valves 13 connected via the high-pressure fuel passage 39. A rail pressure sensor 21 and a pressure control valve 12 are attached to the common rail 10. For example, an electromagnetic proportional control valve is used as the pressure control valve 12, and the amount of the accumulated high-pressure fuel that is discharged to the fuel return path 30 b can be adjusted, and the pressure in the common rail 10 is reduced according to the amount of discharge. Is done. The rail pressure adjusted by the pressure control valve 12 is also a factor that affects the driving torque of the high-pressure pump 5 as in the above-described amount of high-pressure fuel fed to the common rail 10.

  Further, an actual rail pressure signal detected by a rail pressure sensor 21 provided in the common rail 10 is sent to the ECU 40. The ECU 40 controls the pressure control valve 12 provided in the common rail 10 and the flow rate control valve 8 provided in the high-pressure pump 5 so that the actual rail pressure that is sent becomes the target rail pressure.

(4) Fuel Injection Valve The fuel injection valve 13 connected to the common rail 10 includes a nozzle body provided with an injection hole and a nozzle needle that closes the injection hole, and a back pressure acting on the rear end side of the nozzle needle is provided. By being escaped, the nozzle needle is separated from the injection hole, and the high-pressure fuel supplied from the common rail 10 is injected into the cylinder of the internal combustion engine. As the fuel injection valve 13, for example, an electromagnetic control type fuel injection valve provided with a solenoid as a back pressure control unit, or a piezo type fuel injection valve provided with a piezo element as a back pressure control unit is used.

FIG. 2 shows a configuration example of the piezo injector 13 having a back pressure relief mechanism 60 including a piezo actuator 51 as an example of the fuel injection valve 13.
The piezo injector 13 is configured such that fuel is injected by letting the high pressure fuel in the back pressure chamber 91 acting on the rear end side of the nozzle needle 83 escape by the back pressure relief mechanism 60. is there.

In the piezo injector 13 shown in FIG. 2, when high-pressure fuel is introduced from the high-pressure passage 61b of the injector housing 61 in a state where the piezo stack 51A is not extended, the nozzle needle 83 passes through the first hole 75a of the orifice plate 75. The high pressure fuel is guided from the periphery of the nozzle to the injection hole 79b side. The high-pressure fuel is also supplied to the back pressure chamber 91 via the first throttle hole 75b and is also guided to the axial hole 71a of the valve plate 71 via the second throttle hole 75c. At this time, since the reduced diameter portion 71b of the axial hole 71a is closed by the valve member 73, the high-pressure fuel is further guided from the periphery of the nozzle needle 83 to the injection hole 79b side through the third throttle hole 75d. .
In this state, the sum of the pressure that presses the nozzle needle 83 toward the injection hole 79b and the urging force of the needle spring 89 is superior to the pressure that presses the nozzle needle 83 toward the side opposite to the injection hole 79b. The injection hole 79b is closed.

On the other hand, when the piezo actuator 51 is energized and the piezo stack 51 </ b> A is extended, the displacement of the piezo stack 51 </ b> A is transmitted to the pressure-increasing piston 65, and further increased in pressure in the pressure-increasing chamber 66 and transmitted to the valve piston 67. When the valve member 73 is pressed by the valve piston 67, the valve member 73 is separated from the reduced diameter portion 71 b of the axial hole 71 a of the valve plate 71 and the reduced diameter portion 71 b is opened, while the third of the orifice plate 75 is opened. The throttle hole 75d is closed. Then, the back pressure acting on the rear end portion of the nozzle needle 83 in the back pressure chamber 91 is released to the pressure increasing chamber 66 side, so that the pressure for pressing the nozzle needle 83 to the side opposite to the injection hole 79b is increased. The biasing force of the spring 89 is exceeded, the nozzle needle 83 is lifted from the valve seat, and the injection hole 79b is opened.
The fuel that has been used for back pressure control of the nozzle needle 83 and has escaped to the pressure increasing chamber 66 side is caused to flow through the fuel escape passage 61c to the fuel return path 30c and returned to the fuel tank.

  The injection hole 79b provided in the nozzle body 79 of the fuel injection valve 13 used in this embodiment has a relatively small diameter. Therefore, when high pressure fuel of the same pressure is injected, the state of fuel spray is relatively fine and tends to be in a good state. Therefore, the combustion characteristics in the internal combustion engine are improved, and the exhaust gas discharged from the internal combustion engine easily satisfies the exhaust gas regulation value.

2. Fuel injection device control unit (ECU)
(1) Overall Configuration FIG. 3 is a functional block diagram showing the part of the ECU 40 relating to the rail pressure control and the back pressure control of the fuel injection valve 13.
The ECU 40 is configured around a microcomputer having a known configuration, and includes a rated area determination unit, a main injection control unit, a preliminary back pressure control unit, a preliminary back pressure control timing correction unit, and an exhaust. And a temperature determination unit. Specifically, each of these units is realized by executing a program by a microcomputer.

(2) Rated region determination unit The rated region determination unit determines whether or not the internal combustion engine is in the rated operation region based on information such as the rotational speed Ne of the internal combustion engine, the accelerator pedal operation amount Acc, and the vehicle speed Spd. The determination result is output to the preliminary back pressure control unit and the main injection control unit. In the ECU 40 of this embodiment, when the internal combustion engine is in the rated operation region, control by a preliminary back pressure control unit described later is performed.

(3) Main injection control unit When the internal combustion engine is in the rated operation range, the main injection control unit performs a small amount of back pressure relief control by the preliminary back pressure control unit, As the pressure of the high-pressure fuel in the high-pressure fuel passage connecting the two pulsates, the pressure rises and the main injection is performed when the amplitude of the pressure pulsation is positive. To output a drive signal. The fuel injection amount at this time is calculated based on the rotational speed Ne of the internal combustion engine, the accelerator pedal operation amount Acc, the vehicle speed Spd, the sensor value Prail of the rail pressure sensor 21, and the like.
When the pressure of the high-pressure fuel sent to the fuel injection valve 13 is rising and the amplitude of the pulsation of the pressure is positive, the pressure of the high-pressure fuel sent to the fuel injection valve 13 is relatively high, Even if fuel injection is performed, the pressure does not drop suddenly. Therefore, while the fuel injection valve 13 is opened and fuel injection is performed, the pressure of the high-pressure fuel supplied to the fuel injection valve 13 is It is kept at a relatively high pressure. Therefore, by performing fuel injection at this time, the injection time for injecting a predetermined amount of fuel is relatively shortened.

(4) Preliminary back pressure control unit When the internal combustion engine is in the rated operating range, the preliminary back pressure control unit performs a minute amount of back pressure relief control (hereinafter referred to as “preliminary back pressure control” before performing main injection to the internal combustion engine. A drive signal is output to the fuel injection valve 13 so as to be performed. When the piezo injector 13 shown in FIG. 2 is used as the fuel injection valve 13, the energization control for the back pressure relief mechanism 60 of the piezo injector 13 is performed by the preliminary back pressure control unit. The back pressure is released from the back pressure chamber 91 by being separated from the reduced diameter portion 71 b of the plate 71. During this time, the nozzle needle 83 of the piezo injector 13 does not lift from the valve seat, and a so-called idle driving state is formed.

As described above, the preliminary back pressure relief control is preferably idle control in which fuel is not actually injected from the injection hole of the fuel injection valve 13, but conventionally, an internal combustion engine outside the rated operation range is used. The fuel may actually be injected from the fuel injection valve 13 as long as only a small amount of fuel is injected, such as pilot injection that is performed immediately after starting the engine or during high-load operation. . In other words, fuel injection may actually be performed by preliminary back pressure relief control as long as the amount is small enough not to affect the combustion characteristics in the internal combustion engine.
When preliminary back pressure relief control of the fuel injection valve 13 is performed, pulsation occurs in the pressure of the high-pressure fuel sent to the fuel injection valve 13 in the high-pressure fuel passage connecting the common rail and the fuel injection valve 13.

Without shifting the start timing of the main injection, the preliminary pressure is adjusted so that the main injection is performed when the pressure of the high-pressure fuel sent to the fuel injection valve 13 is increased and the pulsation amplitude of the pressure is positive. Various methods are conceivable as a method of adapting the execution timing of the pressure relief control.
For example, a preliminary experiment is performed, and the intervals from the preliminary back pressure relief control to the main injection being performed under the same pressure of the high-pressure fuel sent to the fuel injection valve 13 are set to be constant. Collect the injection amount data when the main injection of the time is performed. Then, the interval corresponding to the data with the largest injection amount is set as the interval under the pressure condition. The relationship between the pressure condition of the high-pressure fuel and the optimum interval is acquired under various pressure conditions, and the interval Int0 corresponding to each pressure condition is stored in the preliminary back pressure control unit, thereby obtaining a predetermined value. The execution time of the preliminary back pressure relief control is adapted so that the main injection is performed when the pressure condition is satisfied.

  Alternatively, in a state in which the internal combustion engine is operated directly rather than in a preliminary experiment, under a condition that the pressure of the high-pressure fuel sent to the fuel injection valve 13 is the same, until a main injection is performed after a minute amount of back pressure relief control is performed. The data of the injection time when a certain amount of main injection is performed is collected at different intervals. Then, an interval corresponding to the data with the shortest injection time may be set as the interval Int0 under the pressure condition.

  Furthermore, in a state where the internal combustion engine is operated directly rather than in a preliminary experiment, the main injection is performed after a small amount of back pressure relief control is performed under the same pressure of the high pressure fuel sent to the fuel injection valve 13. The exhaust temperature data is collected when a certain amount of main injection is performed so that the output of the same internal combustion engine appears at different intervals. Then, an interval corresponding to the data with the lowest exhaust temperature may be set as the interval Int0 under the pressure condition.

(5) Preliminary back pressure control timing correction unit The preliminary back pressure control timing correction unit calculates the temperature Tdsl of the high-pressure fuel sent to the fuel injection valve 13, and performs preliminary back pressure relief according to the calculated temperature. A signal for correcting the timing for performing the control is output to the preliminary back pressure control unit. Specifically, the preliminary back pressure control timing correction unit estimates the temperature of the high-pressure fuel from the operating state of the internal combustion engine, and sets the estimated temperature and the interval Int0 stored in the preliminary back pressure control unit. Based on the difference from the condition temperature, the interval until the main injection is performed is corrected. By correcting the timing of the preliminary back pressure relief control based on the temperature of the high-pressure fuel, the frequency shift of the pressure wave caused by the temperature is eliminated, and the fluctuation of the pressure wave satisfies a predetermined condition. The main injection is accurately performed according to the time to satisfy.
In the ECU 40 of the present embodiment, correction of the execution timing of the preliminary back pressure relief control is performed using the temperature information of the high pressure fuel estimated from the operating state of the internal combustion engine. However, a temperature sensor is provided on the common rail 10, Based on the sensor value of the temperature sensor, the time for performing the preliminary back pressure relief control may be corrected.

(6) Exhaust temperature determination unit Further, the ECU 40 of the present embodiment includes an exhaust temperature determination unit, and when the internal combustion engine is in the rated operation region, the detected exhaust temperature Tgas is likely to exceed a predetermined threshold Tgas0. Only in such a situation, the control by the preliminary back pressure control unit described later is performed. Preliminary back pressure relief control is performed only in a situation where the exhaust gas temperature Tgas is likely to exceed the threshold Tgas0, so that it is possible to perform preliminary back pressure relief control in a situation where the need for control to lower the exhaust gas temperature Tgas is low. Therefore, the increase in the number of injections in the region where the rail pressure is high is suppressed, and the load on the fuel injection valve 13 is reduced.

  The exhaust temperature determination unit of the ECU 40 of the present embodiment reads the sensor value Tenv of the outside air temperature sensor provided in the vehicle, the rotational speed Ne of the internal combustion engine, the gear ratio G, the vehicle speed Spd, etc., and the exhaust discharged from the internal combustion engine The temperature Tgas is estimated, it is determined whether or not the exhaust temperature Tgas is equal to or higher than a predetermined threshold Tgas0, and the determination result is output to the preliminary back pressure control unit and the main injection control unit. This threshold value Tgas0 is set to 800 ° C., for example. Specifically, for example, when the estimated exhaust gas temperature Tgas is equal to or higher than the threshold Tgas0 when the outside air temperature exceeds 40 degrees, the internal combustion engine is running at a high speed and a high gear ratio, and running at a high speed, etc. When the determination is made, preliminary back pressure relief control is executed by the preliminary back pressure control unit.

  The determination method in the exhaust temperature determination unit is not limited to the above-described example. For example, the exhaust temperature is likely to exceed a predetermined threshold using the sensor value of the temperature sensor provided in the exhaust passage of the internal combustion engine. Can also be determined.

3. Fuel Injection Device Control Method Next, an example of a fuel injection device control method performed by the ECU 40 in FIG. 3 will be described. FIG. 4 is a schematic configuration diagram of the fuel injection device 50, FIG. 4 is a control flow diagram, and FIG. This will be described in detail with reference to the drawings.

  First, in step S1, the engine speed Ne, the accelerator pedal operation amount Acc, the vehicle speed Spd, the outside air temperature Tenv, the gear ratio G, and the like are read, and then in step S2, the information read in step S1 and other information are read. The required fuel injection amount is calculated based on the operating state of the internal combustion engine. Next, in step S3, based on the information read in step S1, it is determined whether or not the internal combustion engine is in a rated operation region. If the internal combustion engine is outside the rated operation region, the process proceeds to step S13, and after normal fuel injection control is performed, the process returns to step S1, while if the internal combustion engine is in the rated operation region, the process proceeds to step S4.

  Next, in step S4, after the exhaust gas temperature Tgas is estimated based on the information read in step S1, in step S5, it is determined whether or not the estimated exhaust gas temperature Tgas is equal to or higher than a threshold value Tgas0. When the estimated exhaust gas temperature Tgas is less than the threshold value Tgas0, the process proceeds to step S13, and after normal fuel injection control is performed, the process returns to step S1, while when the estimated exhaust gas temperature Tgas is equal to or higher than the threshold value Tgas, step S13 is performed. Proceed to S6.

Next, in step S6, after the sensor value Prail of the rail pressure sensor 21 provided in the common rail 10 is read, in step S7, based on the sensor value Prail of the rail pressure sensor 21 detected in step S6, a preliminary profile is obtained. An interval Int0 from the pressure relief control to the main injection is set.
Next, in step S8, the temperature Tdsl of the high-pressure fuel sent to the fuel injection valve 13 is calculated based on the operating state of the internal combustion engine. Then, in step S9, step S7 is performed according to the calculated temperature Tdsl of the high-pressure fuel. The value of the interval Int0 set in is corrected. For example, when the calculated value of the temperature Tdsl of the high pressure fuel is higher than the condition temperature when the data used when setting the interval Int0 in step S7 is acquired, the pressure generated in the high pressure fuel passage 39 Since the frequency of the pulsation becomes shorter, the correction is performed so that the interval Int until the main injection becomes shorter.

  Next, in step S10, a signal is sent to the back pressure relief mechanism of the fuel injection valve 13, and preliminary back pressure relief control is performed so that a small amount of back pressure in the back pressure chamber is released (t1 in FIG. 5). ). At the same time, a timer is activated. By this preliminary back pressure relief control, the pressure of the high pressure fuel sent to the fuel injection valve 13 is once reduced, and pressure pulsation is generated in the high pressure fuel passage 39.

  Next, in step S11, it is determined whether or not the value of the timer operated in step S10 has passed the interval Int corrected in step S9 (period t1 to t2 in FIG. 5). When Int is reached (t2 in FIG. 5), the process proceeds to step S12.

Next, at step S12, a signal is sent to the back pressure relief mechanism of the fuel injection valve 13, and the back pressure in the back pressure chamber is released, so that main injection is performed. At this time, the main injection is performed when the pressure rises with respect to the pulsation of the pressure generated in the high-pressure fuel passage 39 and when the pressure amplitude is positive.
Thereafter, the process returns to step S1 again, and the steps so far are repeated.

As described above, in the rated operation region of the internal combustion engine, by performing the preliminary back pressure relief control before performing the main injection, as shown in the transition of the fuel injection amount in FIG. The time required to inject the requested fuel injection amount calculated in step S1 is shortened, and the increase in the exhaust temperature is suppressed without lowering the output of the internal combustion engine.
Further, as a result of such preliminary back pressure relief control, not only the pressure peak in the high pressure fuel passage decreases, but also the common rail as shown in FIG. In addition, since the pressure peak in the fuel injection valve also decreases, damage to the common rail, the high-pressure fuel passage, and the fuel injection valve due to pressure pulsation is reduced, and the long-term reliability of the fuel injection device is improved.

  And since the rise in the exhaust temperature is suppressed and damage to the common rail, the high pressure fuel passage, and the fuel injection valve is reduced, a smaller injection hole can be selected and the output of the internal combustion engine can be increased. It will be possible to comply with exhaust gas regulations.

Claims (4)

Fuel injection for supplying fuel to an internal combustion engine using a fuel injection valve in which the injection hole is opened by releasing a back pressure acting on the rear end side of the nozzle needle that closes the injection hole. In a control device for a fuel injection device for controlling the device,
A rated region determination unit for determining whether or not the internal combustion engine is in a rated operation region;
When the internal combustion engine is in a rated operation range, before the main injection to the internal combustion engine, the fuel injection is not performed from the injection hole of the fuel injection valve as a small amount of back pressure relief control A preliminary back pressure control unit,
Main injection that performs the main injection when the pressure rises and the amplitude of the pressure is positive with respect to the pulsation of the pressure of the high-pressure fuel sent to the fuel injection valve caused by the small amount of back pressure relief control A control unit;
A preliminary back pressure control timing correction unit that detects the temperature of the high pressure fuel sent to the fuel injection valve and corrects the timing of performing the minute amount of back pressure relief control in accordance with the temperature of the high pressure fuel;
A control device for a fuel injection device.
Fuel injection for supplying fuel to an internal combustion engine using a fuel injection valve in which the injection hole is opened by releasing a back pressure acting on the rear end side of the nozzle needle that closes the injection hole. In a control device for a fuel injection device for controlling the device,
A rated region determination unit for determining whether or not the internal combustion engine is in a rated operation region;
When the internal combustion engine is in a rated operation range, before the main injection to the internal combustion engine, the fuel injection is not performed from the injection hole of the fuel injection valve as a small amount of back pressure relief control A preliminary back pressure control unit,
Main injection that performs the main injection when the pressure rises and the amplitude of the pressure is positive with respect to the pulsation of the pressure of the high-pressure fuel sent to the fuel injection valve caused by the small amount of back pressure relief control A control unit;
An exhaust temperature determination unit that performs the minute amount of back pressure relief control in a rated operation region of the internal combustion engine when the exhaust temperature discharged from the internal combustion engine is equal to or higher than a predetermined threshold;
Control device for fuel injection device you comprising: a.
Fuel injection for supplying fuel to an internal combustion engine using a fuel injection valve in which the injection hole is opened by releasing a back pressure acting on the rear end side of the nozzle needle that closes the injection hole. In the device control method,
In a state where the internal combustion engine is in a rated operation region, a pulsation is caused in the pressure of the high-pressure fuel sent to the fuel injection valve by performing a small amount of back pressure relief control before performing the main injection to the internal combustion engine, The main injection is performed when the pressure rises and the pressure amplitude is positive,
The minute amount of back pressure relief control is idle control in which the fuel injection is not performed from the injection hole of the fuel injection valve,
A control method for a fuel injection device, wherein the timing for performing the idling control is corrected in accordance with the temperature of the high-pressure fuel.
Fuel injection for supplying fuel to an internal combustion engine using a fuel injection valve in which the injection hole is opened by releasing a back pressure acting on the rear end side of the nozzle needle that closes the injection hole. In the device control method,
In a state where the internal combustion engine is in a rated operation region, a pulsation is caused in the pressure of the high-pressure fuel sent to the fuel injection valve by performing a small amount of back pressure relief control before performing the main injection to the internal combustion engine, The main injection is performed when the pressure rises and the pressure amplitude is positive,
The minute amount of back pressure relief control is idle control in which the fuel injection is not performed from the injection hole of the fuel injection valve,
A control method for a fuel injection device, comprising: performing the idling control in a rated operation region of the internal combustion engine when an exhaust gas temperature discharged from the internal combustion engine is equal to or higher than a predetermined threshold value.

Images