JP2008057382A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device for an internal combustion engine capable of more reduction of operation limitation area. <P>SOLUTION: The fuel injection device for the internal combustion engine 1 accumulating high pressure fuel pressurized and fed by a supplier pump 2 in a pressure accumulation rail 3, distributing and supplying the high pressure fuel to an injector 4 installed for each cylinder of the internal combustion engine 1, and injecting and supplying the high pressure fuel to a combustion chamber 5 of each cylinder from the injector 4 by exciting the injector 4, is provided with a fuel temperature measuring means 24 detecting or estimating fuel temperature, a fuel remaining quantity measuring means 23 detecting or estimating quantity of fuel remaining in a fuel tank 7, and an accumulation pressure correcting means 6 correcting accumulation pressure in the pressure accumulation rail 3 to lower accumulation pressure as compared to pressure when remaining fuel quantity is greater than a predetermined quantity when fuel temperature detected or estimated by the fuel temperature measuring means 24 exceeds a predetermined quantity and remaining fuel quantity detected or estimated by the fuel remaining quantity measuring means 23 is reduced from the predetermined quantity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection device for an internal combustion engine having a fuel injection valve (injector) that injects accumulated high-pressure fuel into each cylinder of the internal combustion engine, and more particularly to an internal combustion engine suitable for suppressing an excessive increase in fuel injection valve temperature. The present invention relates to a fuel injection device.

  In response to stricter exhaust gas regulations and higher engine output, the pressure-accumulated fuel has been increased, but with this increase in pressure, the temperature of the fuel injection valve (injector) that injects the high-pressure accumulated fuel into each cylinder There is a problem of over rising. In order to eliminate this excessive increase in temperature, it is effective to reduce the fuel temperature by lowering the fuel injection amount or lowering the common rail pressure when the temperature rises. It is known that the drivability (driving performance) of a vehicle equipped with a pressure-accumulation fuel injection system is reduced with a decrease in engine output.

  For this reason, conventionally, there has been proposed a fuel injection device that suppresses an excessive increase in injector temperature and suppresses a decrease in drivability of the vehicle to increase the pressure of the accumulated fuel (see Patent Documents 1 and 2).

  In Patent Document 1, a current correction coefficient is calculated based on a difference between an injector temperature and a predetermined value, a common rail pressure detected by a sensor, and a characteristic diagram. When the current correction coefficient is set to be much lower than normal, and the injector temperature exceeds a predetermined value, the drive current value to the solenoid coil of the injector is reduced according to the operating conditions, so that the solenoid The amount of heat generated by the coil is suppressed.

In Patent Document 2, the temperature increase rate of leaked fuel that is not injected by the injector and leaks and returns to the fuel tank is calculated according to the operating condition of the engine, and the accumulated fuel is calculated based on the temperature increase rate. The conditions for starting operation restriction (output reduction operation due to a decrease in guardrail pressure or a decrease in injection amount) for suppressing the temperature increase of the engine are changed.
JP 2003-278586 A JP 2006-29288 A

  However, in the above-mentioned Patent Document 1, when the fuel temperature exceeds a certain predetermined value, the injection pressure restriction and the suppression of the heat generation amount of the injector are started. Depending on the rate, the fuel temperature may exceed the allowable value. Further, if the predetermined value for starting the injection pressure restriction is set too low, a region where the target injection pressure corresponding to the operating state of the engine cannot be generated is expanded, and the output is reduced accordingly.

  Further, in Patent Document 2, since the start rate of the operation restriction is set by estimating the rate of increase of the fuel temperature according to the engine operating condition, the region where the operation is restricted can be reduced. However, after the fuel is leaked and returned to the fuel tank and heat exchange with the remaining fuel existing in the fuel tank is performed, the fuel temperature when the fuel tank is supplied again as the pressure accumulation fuel is the magnitude of the remaining fuel (heat capacity) of the fuel tank. Therefore, when there is a relatively large amount of remaining fuel in the fuel tank, the operation is restricted despite the fuel temperature rising at a lower rate than the estimated rate of increase in fuel temperature. It is expected that it will end.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel injection device for an internal combustion engine that can further reduce the operation restriction region.

  The present invention accumulates high-pressure fuel pumped from a high-pressure pump in an accumulator rail, distributes and supplies the high-pressure fuel to injectors installed in each cylinder of an internal combustion engine, and the injector is energized to supply power from the injector. Fuel temperature measuring means for detecting or estimating fuel temperature and fuel remaining amount measurement for detecting or estimating the remaining amount of fuel in a fuel tank in a fuel injection device for an internal combustion engine that supplies high pressure fuel injected into the combustion chamber of each cylinder And the fuel temperature detected or estimated by the fuel temperature measuring means exceeds a preset predetermined value, and the fuel remaining amount detected or estimated by the fuel residual quantity measuring means is reduced from a preset predetermined amount. Pressure accumulation correction means for correcting the pressure accumulation pressure of the pressure accumulation rail to be lower than when the remaining amount of fuel is greater than the predetermined amount. Was Unishi.

  Therefore, according to the present invention, the fuel temperature detected or estimated by the fuel temperature measuring unit exceeds a predetermined value set in advance, and the fuel remaining amount detected or estimated by the remaining fuel level measuring unit is decreased from the predetermined amount set in advance. In order to correct the pressure accumulation pressure of the pressure accumulation rail to be lower than when the remaining amount of fuel is greater than the predetermined amount, the operation restriction is accompanied by a decrease in output when the fuel temperature rises in a hot place or in summer. The operating area of the state can be reduced, and its operating frequency can be reduced.

  Hereinafter, a fuel injection device for an internal combustion engine of the present invention will be described based on each embodiment.

(First embodiment)
1 to 4 show a first embodiment of a fuel injection device for an internal combustion engine to which the present invention is applied, FIG. 1 is a system configuration diagram of the fuel injection device for the internal combustion engine, and FIG. 2 is a diagram of the fuel injection device for the internal combustion engine. FIG. 3 is a control flowchart, FIG. 3 is an explanatory diagram showing an operation restriction region in this embodiment, and FIG.

  In FIG. 1, a fuel injection device for an internal combustion engine constitutes a common rail fuel injection system, and is supplied from a supply pump 2 that is rotationally driven by an internal combustion engine 1 (hereinafter referred to as an engine) such as a diesel engine, and discharged from the supply pump 2. A common rail 3 constituting an accumulator tank for accumulating the high-pressure fuel, and a plurality of injectors 4 with solenoid valves (hereinafter referred to as injectors) for injecting the high-pressure fuel accumulated in the common rail 3 into the combustion chamber 5 of each cylinder of the engine 1 And an engine controller 6 (ECU) that electronically controls the supply pump 2 and the plurality of injectors 4.

  The supply pump 2 introduces the fuel discharged from the fuel pump 14 in the sender unit 8 disposed in the fuel tank 7 through the fuel filter 9 and the feed pipe 10, and with the rotation of the crankshaft of the engine 1. A low pressure feed pump that is rotated to pressurize the introduced fuel to a relatively low pressure, and a high pressure plunger that is driven as the crankshaft rotates to pressurize the low pressure fuel from the feed pump and discharge it to the common rail 3 A pump. The leaked fuel from the supply pump 2 is returned to the return pipe 11 and returned from the sender unit 8 to the fuel tank 7 via the fuel cooler 12. In a cold region specification vehicle, a fuel return control system 13 (FRCS) that returns the leaked fuel once heated by the supply pump 2 in the return pipe 11 directly to the feed pipe 10 of the fuel supply system. Is arranged.

  When the high pressure fuel discharged from the supply pump 2 is continuously supplied to the common rail 3 and accumulated at a high pressure (common rail pressure) corresponding to the fuel injection pressure, the common rail pressure exceeds the limit set pressure. The relief valve (not shown) is returned to the return pipe 11 to prevent the common rail pressure from becoming higher than the limit set pressure. The common rail pressure is adjusted by adjusting a suction adjusting valve (not shown) provided upstream of the supply pump 2 by the engine controller 6, and the pressure in the common rail 3 is detected by the pressure sensor 20 and fed back to the engine controller 6.

  An injector 4 provided for each cylinder of the engine 1 is connected downstream of a branch pipe branched from the common rail 3 and is supplied with high pressure fuel injected into the combustion chamber 5 of each cylinder of the engine 1 (not shown). An injection valve, an electromagnetic solenoid as an electromagnetic actuator that drives the needle of the injection valve in the valve opening direction, and a valve spring that biases the needle in the valve closing direction are provided. The high-pressure fuel supplied via the branch pipe is injected into the combustion chamber 5 by opening the injection valve driven by the electromagnetic solenoid, and part of the fuel moves around the electromagnetic solenoid as the electromagnetic solenoid operates. The electromagnetic solenoid is cooled by passing, and then returned to the return pipe 11. The fuel injection from each injector 4 is electronically controlled by an electromagnetic valve control signal output from an engine controller 6 (ECU) to a drive circuit (not shown) that drives an electromagnetic solenoid.

  The engine controller 6 (ECU) includes a CPU that performs control processing and arithmetic processing, a ROM that stores and stores various programs and data, a microcomputer such as a RAM, an input circuit, an output circuit, and a microcomputer. A power supply circuit, an injector drive circuit, and the like are included. The engine controller 6 is provided with an accelerator position signal (ACCEL) and an engine speed signal (Ne) from the accelerator position sensor 21 and the engine speed sensor 22 as vehicle driving information, and is provided in the sender unit 8 of the fuel tank 7. The remaining fuel signal (FL) from the remaining fuel sensor 23 (remaining fuel measuring means), the fuel temperature signal (THFL) from the fuel temperature sensor 24 (fuel temperature measuring means) disposed in the feed pipe 10, and the common rail A common rail pressure signal (PC) from the pressure sensor 20 and a cooling water temperature signal (TC) from the engine water temperature sensor 25 are input.

  Further, the storage device of the engine controller 6 (ECU) stores a target fuel pressure map of the common rail 3 according to the accelerator opening signal (engine load ACCEL) and the engine speed (Ne), an accelerator opening signal (engine load ACCEL). ) And the required fuel amount per cylinder according to the engine speed (Ne), the map of the valve opening pulse width of the injector 4 according to the required fuel amount per cylinder and the target fuel pressure, the remaining fuel amount (FL ) And the fuel temperature (THFL) are stored in advance as maps in which the operation restriction ratios are set as parameters.

  In the engine controller 6, the actual fuel pressure (PC) of the common rail 3 detected by the fuel pressure sensor 20 depends on the accelerator opening signal (engine load ACCEL) and the rotational speed (Ne) of the engine 1 at that time. Thus, the discharge amount of the high-pressure plunger pump in the supply pump 2 is controlled via a suction adjustment valve (not shown) so as to coincide with the target fuel pressure set in the map. For example, when the actual common rail fuel pressure (PC) is lower than the target fuel pressure, the discharge amount of the high pressure plunger pump is increased by increasing the discharge amount of the high pressure plunger pump by increasing the timing of closing the passage by the intake regulating valve. Approach the target fuel pressure. On the contrary, when the actual common rail fuel pressure (PC) is higher than the target fuel pressure, the timing at which the intake regulating valve closes the passage is delayed to reduce the discharge amount of the high pressure plunger pump and to decrease the actual common rail fuel pressure (PC). Close to the target fuel pressure. The common rail fuel pressure (PC) is determined by the fuel supply to each combustion chamber 5 by fuel injection at a predetermined timing by the injector 4 of each cylinder, whereby the fuel pressure (PC) in the common rail 3 disappears. Therefore, the control of the common rail fuel pressure (PC) described above (the discharge amount control of the high pressure plunger pump) is always executed.

  If the accelerator opening signal (engine load ACCEL) and the rotational speed (Ne) are determined, the required fuel amount per cylinder is uniquely determined. If the required fuel amount per cylinder and the target fuel pressure are determined, the injector The valve opening pulse width of 4 is determined. The engine controller 6 searches the map of the required fuel amount per cylinder and the map of the target fuel pressure from the accelerator opening signal (engine load ACCEL) and the rotational speed (Ne) at that time, and requests the required fuel per cylinder. The amount and the target fuel pressure are obtained, and a map of the fuel injection pulse width is further retrieved from these to obtain the valve opening pulse width of the injector 4, and when the predetermined injection timing is reached, the injector 4 is opened with this valve opening pulse width. To supply fuel to each cylinder.

  As shown in FIG. 3, the map in which the remaining fuel amount and the fuel temperature are used as parameters to store the operation restriction ratio is low, and the fuel temperature (FL) in the fuel tank 7 is small and the fuel temperature ( (THF) is set as a driving restriction area B (for example, 80%), and a transition area set by raising the predetermined temperature as the remaining amount of fuel increases, and is included in the driving restriction area B. A region where there is a large amount of remaining fuel and a region where the fuel temperature is lower than a preset temperature are set as an operation restriction unnecessary region A (100%). An operation restriction relaxation that is an intermediate stage between the operation restriction area B and the operation restriction unnecessary area A is a region where the fuel temperature is equal to or higher than a predetermined temperature that is not included in the operation restriction region B. The area C (for example, 90%) may be set.

  FIG. 4 shows the rate of increase of the fuel temperature with respect to the remaining amount of fuel in the fuel tank 7. The fuel supplied from the fuel tank 7 to the engine 1 is boosted by the supply pump 2, so that the temperature is increased by the heat of the electromagnetic solenoids of the engine 1 and the injector 4, and the fuel is sequentially injected into the combustion chamber 5 by the injector 4. The Return fuel that is recirculated from the engine 1 without being injected from the injector 4 is returned into the sender unit 8 of the fuel tank 7 in a state where the temperature has increased.

  In the center unit, the return fuel recirculated from the engine 1 and the remaining fuel flowing in from the outside of the sender unit 8 are mixed with the fuel in the sender unit 8 and its temperature is raised, while the remaining fuel outside the sender unit 8 is increased. Cooled by heat exchange with quantity fuel. Therefore, the temperature of the fuel sucked by the fuel pump 14 and supplied to the engine 1 is determined whether it rises or falls depending on the balance between the amount of heat input by the return fuel and the amount of heat released by heat exchange with the remaining fuel outside. .

  In the region F where the remaining amount of fuel in the fuel tank 7 is more than half of the tank capacity, the liquid level level of the remaining fuel outside is high, so that the sender unit 8 is below the liquid level. Although the capacity of the remaining fuel outside is large and its heat capacity is large, the temperature rises gradually, heat exchange between the inside and outside of the sender unit 8 is actively performed, and the rise in fuel temperature inside the sender unit 8 is suppressed.

  In the FE region where the fuel remaining in the fuel tank 7 is reduced to less than half of the tank capacity, the liquid level of the residual fuel inside and outside the sender unit 8 is approximately equal or the liquid level outside the sender unit 8 is slightly higher. Thus, the heat exchange area between the inside and outside of the sender unit 8 is reduced and the remaining fuel capacity outside the sender unit 8 is reduced, so that the heat capacity is also reduced, and the temperature is relatively easily increased. For this reason, as the remaining fuel level decreases, heat exchange between the inside and outside of the sender unit 8 is also gradually reduced, and the temperature rise in the sender unit 8 is also gradually increased.

  In the region E where the remaining amount of fuel in the fuel tank 7 is lowered to a state warned by the remaining amount warning light, the liquid level of the residual fuel inside and outside the sender unit 8 is approximately equal or low, or the liquid in the sender unit 8 is low. As the surface level becomes slightly higher, the heat exchange area between the inside and outside of the sender unit 8 becomes smaller and the remaining fuel capacity outside the sender unit 8 also becomes smaller, so that the heat capacity becomes smaller and the temperature rises. It becomes easy. For this reason, as the remaining fuel level decreases, heat exchange between the inside and outside of the sender unit 8 is further reduced, and the temperature rise in the sender unit 8 also increases.

  The operation restriction region B in the map in which the operation restriction ratio is stored is the fuel from the stage where the remaining fuel amount is reduced to about 1/3 based on the temperature rise characteristic of the remaining fuel in the sender unit 8 of the fuel tank 7. As the remaining amount decreases, the temperature at which the operation restriction is started is gradually lowered, and when the remaining fuel amount is reduced to about 1/4 or less immediately before the remaining amount warning is issued, the temperature at which the operation restriction is started is previously set. The temperature is set to be the same.

  When the engine controller 6 monitors the fuel temperature from the fuel temperature sensor 24 and the remaining amount of fuel in the fuel tank 7, and determines that these sensor signals exist in the operation restriction region B (or the operation restriction relaxation region C). The target common rail fuel pressure is adjusted by lowering the target common rail fuel pressure by multiplying the limit ratio read from the map in which the operation limit ratio is stored, and adjusting the target common rail pressure so as to decrease the target common rail fuel pressure to the common rail pressure. Thus, when the target common rail pressure is reduced, the target fuel injection amount is changed according to the pressure drop. In order to prevent the combustion state in the combustion chamber 5 from changing, the fuel injection pulse width of the fuel injection valve is not changed.

  Next, calculation control of the target rail pressure and the target injection amount executed by the engine controller 6 will be described with reference to FIG. FIG. 2 is a flowchart of calculation control of the target rail pressure and the target injection amount that is repeatedly executed by the engine controller 6 every predetermined time (for example, 10 ms).

  First, in step 1, the accelerator opening signal (ACCEL) from the accelerator opening sensor 21, the engine speed signal (Ne) from the engine speed sensor 22, the fuel temperature signal (THFL) from the fuel temperature sensor 24, the fuel The fuel remaining amount signal (FL) is read from the remaining amount sensor 23, and the process proceeds to Step 2.

  In step 2, the target fuel injection amount (Q) is calculated by referring to the map of the required fuel amount per cylinder based on the accelerator opening signal (ACCEL) and the engine speed (Ne), and the process proceeds to step 3.

  In step 3, the target rail pressure (P) is calculated by referring to the target fuel pressure map of the common rail 3 based on the accelerator opening signal (ACCEL) and the engine speed (Ne), and the process proceeds to step 4.

  In step 4, the region determined by the current fuel remaining amount and fuel temperature is referred to the rail pressure limiting region B (or the fuel temperature signal (THFL) and the fuel remaining amount (FL) with reference to the operation restriction ratio setting map. It is determined whether or not the operation restriction mitigation region C), and if it is not the rail pressure restriction region B (or operation restriction mitigation region C), the process proceeds to step 12, and the target fuel injection calculated in step 2 and step 3 is performed. The quantity (Q) and the target rail pressure (P) are set as the final target fuel injection quantity (QFIN) and the final target rail pressure (PFIN), and are output to the injector drive circuit and the intake metering valve.

  In Step 4, when it is determined that the region determined by the current remaining fuel amount and the fuel temperature is the rail pressure limiting region B (or the operation limitation mitigating region C), Step 5 to Step 11 are executed, The target fuel injection amount and the target rail pressure in the pressure restriction region B (or the operation restriction relaxation region C) are calculated, and in step 12, the target fuel injection amount and the target rail pressure calculated in these steps are used as the final target fuel injection amount. (QFIN) and final target rail pressure (PFIN) are set and output in the same manner.

  That is, in step 5, the guard rail pressure (PGD) during the limited operation is calculated by multiplying the operation limit ratio determined in step 4 with the target rail pressure (P) calculated in step 3 as a reference, and the process proceeds to step 6 .

  In Step 6, the target rail pressure (P) calculated in Step 3 and the guard rail pressure (PGD) calculated in Step 5 are compared to select a lower (low) rail pressure, and the process proceeds to Step 7.

  In step 7, a rail pressure decrease rate (PDWN) is calculated according to a temperature difference between the detected fuel temperature (THFL) and a predetermined temperature set in advance. That is, the rail pressure decrease rate (PDWN) is set to be large when the temperature difference is large, and the rail pressure is quickly decreased, and is set to be small when the temperature difference is small, and the rail pressure gradually decreases. To be reduced. In this way, by setting the rail pressure decrease speed (PDWN) according to the temperature difference, a sudden output decrease is suppressed and the uncomfortable feeling of deceleration generated in the vehicle is alleviated.

  In Step 8, the final target rail pressure (PFIN) obtained by subtracting the rail pressure decrease speed (PDWN) calculated in Step 7 from the target rail pressure (P) calculated in Step 3 is calculated, and the process proceeds to Step 9. Thus, by reducing the final target rail pressure (PFIN), the amount of pressure increase in the supply pump 2 and the amount of heat generation due to the decrease in the amount of drive current to the electromagnetic solenoid of the injector 4 are reduced. 4 The temperature of the fuel is lowered.

  In step 9, based on the final target rail pressure (PFIN) calculated in step 8, the guard fuel injection amount (QGD) that can be supplied without changing the fuel injection pulse width at that time is calculated, and the process proceeds to step 10 . This guard fuel injection amount (QGD) is that the final target rail pressure (PFIN) is reduced from the target rail pressure (P) calculated in step 3 by the rail pressure decrease rate (PDWN) calculated in step 7. The target fuel injection amount (Q) calculated in step 2 is reduced.

  In step 10, the guard fuel injection amount (QGD) calculated in step 9 and the target fuel injection amount (Q) calculated in step 2 are compared, and a smaller fuel injection amount is selected. In step 11, the fuel injection amount selected in step 10 is calculated as the final fuel injection amount (QFIN), and the process proceeds to step 12.

  In step 12, the set values calculated in steps 8 and 11 are set as the final target fuel injection amount (QFIN) and final target rail pressure (PFIN) in the current process in the operation restriction region, and the injector is driven. Output to circuit and suction metering valve.

  By repeating the above processing steps every predetermined time, the actual rail pressure PC can be gradually lowered to the guardrail pressure PGD calculated in step 5. Then, the engine 1 can be limitedly operated not only in the fuel temperature but also in the limited operation region B (and C) in consideration of the fuel temperature increase rate due to the fuel remaining amount in the fuel tank 7, and the rail pressure is reduced. It is possible to reduce a region where the operation of the engine 1 is restricted by reducing the output. In other words, there is a large amount of fuel remaining in the operation restriction region by controlling at the same operation restriction ratio when the fuel remaining amount is large and the fuel temperature rising rate is small and when the fuel remaining amount is small and the fuel temperature rising rate is large. It is possible to prevent the operation from being restricted in the region where the fuel temperature rise rate is low. For this reason, it is possible to improve drivability especially in summer and in hot areas.

  Further, considering the heat capacity of the fuel tank 7, the cooling capacity of the cooling device such as the fuel cooler 12 can be reduced, and the cost can be reduced.

  In the present embodiment, the following effects can be achieved.

  (A) The high-pressure fuel pumped from the supply pump 2 which is a high-pressure pump is stored in the pressure-accumulating rail 3, and the high-pressure fuel is distributed and supplied to the injectors 4 provided for each cylinder of the internal combustion engine 1. In the fuel injection device of the internal combustion engine 1 for supplying the high pressure fuel by injecting the fuel from the injector 4 to the combustion chamber 5 of each cylinder by being energized, the fuel temperature measuring means 24 for detecting or estimating the fuel temperature, and the fuel tank 7 The remaining fuel amount measuring means 23 for detecting or estimating the remaining fuel amount, and the fuel temperature detected or estimated by the fuel temperature measuring means 24 exceeds a predetermined value set in advance and detected by the remaining fuel amount measuring means 23 or When the estimated remaining fuel amount is reduced from a predetermined amount set in advance, the accumulated pressure of the accumulator rail 3 is larger than when the remaining fuel amount is larger than the predetermined amount. The accumulation pressure correcting means 6 for correcting to decrease, and so comprises a. For this reason, when the fuel temperature rises in a hot area or in summer, the operating region in the operation restricted state accompanied by a decrease in output can be reduced, and the operating frequency can be reduced.

  (A) The region B to be corrected so as to reduce the accumulated pressure includes a transition region in which a predetermined value of the preset fuel temperature is increased and divided as it increases from the preset remaining fuel amount, thereby providing a remaining fuel amount. If the fuel temperature is raised so as to fall within the divided area even if the remaining fuel amount is 1/3 to 1/2 of the relatively secured tank capacity, the injector temperature is reliably set as the operation restricted state. Can be reduced.

  (C) The accumulated pressure correction means 6 reduces the accumulated fuel pressure when the remaining fuel amount is detected or estimated by the remaining fuel amount measuring means 23, so that the remaining fuel amount is less. When the fuel temperature rises, which is likely to increase, the injector temperature can be reliably lowered as the operation restricted state.

  (D) Accumulated pressure correction means 6 quickly decreases the fuel temperature by increasing the rate of decrease of the accumulated pressure in accordance with the fuel temperature detected or estimated by the fuel temperature measuring means 24, and sets the injector temperature. Can be reduced.

(Second Embodiment)
5 to 7 show a second embodiment of a fuel injection device for an internal combustion engine to which the present invention is applied, and FIG. 5 is a map in which an operation restriction ratio is stored with the remaining fuel amount and fuel temperature as parameters, FIG. FIG. 7 is a first embodiment of the control flowchart of the fuel injection device, and FIG. 7 is a second embodiment of the control flowchart of the fuel injection device of the internal combustion engine. In the present embodiment, a configuration in which the operation restriction ratio is set with the remaining fuel amount and the fuel temperature as parameters is added to the first embodiment. In addition, the same code | symbol is attached | subjected to the same apparatus and member as 1st Embodiment, and the description is abbreviate | omitted or simplified.

  As shown in FIG. 5, the map in which the operation restriction ratio is set in the present embodiment increases the operation restriction ratio as the remaining amount of fuel in the fuel tank 7 is small and the fuel temperature rises (the restriction amount is reduced). It is characterized by mapping the remaining fuel amount and the fuel temperature as parameters. The system configuration of the fuel injection device of the internal combustion engine 1 is basically the same as that of the first embodiment.

  Further, the first embodiment of the calculation control of the target rail pressure and the target injection amount executed every predetermined time by the engine controller 6 is constituted by a flowchart shown in FIG. This flowchart is different from the flowchart shown in FIG. 2 of the first embodiment in the process of step 15 and the other processes are basically the same. Below, the part different from 1st Embodiment is demonstrated.

  That is, in step 15, the operation restriction ratio is calculated based on the fuel remaining amount FL and the fuel temperature THFL at that time with reference to the map in which the operation restriction ratio shown in FIG. 5 is set. Therefore, even if the fuel temperature is the same, if the fuel remaining amount FL is different, the operation restriction ratio is increased (the restriction amount is larger) as the fuel remaining amount FL is smaller, and the operation restriction ratio is larger as the fuel remaining amount FL is larger. Is reduced (small amount of restriction). Conversely, even if the fuel remaining amount FL is the same, the operation restriction ratio increases (the restriction amount is large) as the fuel temperature THFL is high, and the operation restriction ratio decreases (the restriction amount is small) as the fuel temperature THFL is low. )

  As described above, by changing the operation restriction ratio using both the fuel remaining amount and the fuel temperature as parameters, the fuel remaining amount is large and the fuel temperature rising rate is small. The operation restriction ratio can be set finely when the value is large.

  In the control flowchart shown in FIG. 6, the rail pressure decrease rate PDWN in step 7 can be set according to the temperature difference between the fuel temperature THFL and the fuel temperature at which the operation restriction is started, as in the first embodiment. Further, it can be set according to the temperature difference between the fuel temperature THFL and the fuel temperature at which the operation restriction is started and according to the remaining fuel amount FL. This is to set the rail pressure decrease speed PDWN in accordance with the amount of restriction in the map of the operation restriction ratio shown in FIG. 5, and it is possible to make finer settings.

  In the control flowchart of the calculation control of the target rail pressure and the target injection amount of the second embodiment shown in FIG. 7, step 16 and step 17 are executed following step 3 of the flowchart of the first embodiment to determine the fuel temperature. When THFL exceeds a preset temperature, a fuel remaining amount warning lamp is turned on early before the remaining amount of fuel reaches the warning point.

  That is, in step 16, the fuel temperature THFL exceeds the preset temperature, and the fuel remaining level FL is approaching the level for warning the remaining fuel level (for example, about 1/5 of the tank capacity). Determine that: When these conditions are satisfied, the routine proceeds to step 17 where the fuel remaining amount warning lamp is turned on to prompt fuel supply to the fuel tank 7. When the fuel tank 7 is refueled, fuel that has not risen in temperature is added, and the fuel remaining amount FL is increased and the rate of increase in fuel temperature is reduced, so that the fuel temperature is also lowered. The operation restriction state is released. If it is determined in step 16 that the above condition is not satisfied, the process proceeds to step 15 which is the next step without passing through step 17.

  In the present embodiment, in addition to the effects (a) and (d) in the first embodiment, the following effects can be achieved.

  (E) The high-pressure fuel pumped from the supply pump 2 which is a high-pressure pump is stored in the pressure-accumulating rail 3, and the high-pressure fuel is distributed and supplied to the injectors 4 provided for each cylinder of the internal combustion engine 1. In the fuel injection device of the internal combustion engine 1 for supplying the high pressure fuel by injecting the fuel from the injector 4 to the combustion chamber 5 of each cylinder by being energized, the fuel temperature measuring means 24 for detecting or estimating the fuel temperature, and the fuel tank 7 When the fuel temperature detected or estimated by the fuel temperature measuring means 24 exceeds a predetermined value, the fuel temperature is detected at the predetermined value. The correction is made so that the accumulated pressure of the accumulator rail is lowered compared to when it is lower, and the fuel remaining amount detected or estimated by the fuel remaining amount measuring means 23 is adjusted. And so it comprises a accumulation pressure correcting means 6 for reducing the decrease correction amount of the accumulator pressure Te. For this reason, when the remaining amount of fuel is large and the fuel temperature is difficult to rise, the operation restriction is weakened. When the remaining fuel amount is low and the fuel temperature is likely to rise, the operation restriction can be strengthened. When the fuel temperature rises, it is possible to reduce the operation range in the operation restricted state accompanied by a decrease in output, and to reduce the operation frequency.

  (F) The accumulated pressure correction means 6 increases the fuel pressure detected by the fuel temperature measuring means 24 and increases the decrease correction amount of the accumulated pressure, thereby limiting the operation as the fuel temperature rises. The fuel temperature and the injector temperature can be reliably lowered.

  (G) The accumulated pressure correcting means 6 reduces the accumulated pressure pressure decreasing rate in accordance with the remaining fuel amount detected or estimated by the remaining fuel amount measuring means 23, thereby reducing the remaining fuel amount and increasing the fuel temperature. When it is easy to do this, it is possible to execute the operation restriction promptly.

The system block diagram of the fuel-injection apparatus of the internal combustion engine which shows one Embodiment of this invention. The flowchart of the calculation control of the target rail pressure and target injection amount which are similarly performed with a controller. Explanatory drawing which shows the driving | operation limitation area | region in this embodiment. Explanatory drawing which shows the raise rate of the fuel temperature with respect to the fuel remaining amount of a fuel tank. The map which memorize | stored the driving | running | working restriction | limiting ratio by making into a parameter the fuel remaining amount and fuel temperature in the fuel injection apparatus of the internal combustion engine which shows 2nd Embodiment of this invention. The flowchart of the calculation control of the target rail pressure and the target injection quantity of 1st Example in 2nd Embodiment. The flowchart of the calculation control of the target rail pressure and the target injection quantity of 2nd Example in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine, engine 2 Supply pump as high pressure pump 3 Common rail as pressure accumulation rail 4 Injector 5 Combustion chamber 6 Engine controller 7 Fuel tank 8 Sender unit 14 Fuel pump 20 Pressure sensor 21 Accelerator opening sensor 22 Engine speed sensor 23 Fuel Fuel remaining amount sensor as remaining amount measuring means 24 Fuel temperature sensor as fuel temperature measuring means

Claims (7)

The high-pressure fuel pumped from the high-pressure pump is accumulated in the accumulator rail, the high-pressure fuel is distributed and supplied to the injectors installed in each cylinder of the internal combustion engine, and the injector is energized to burn each cylinder from the injector. In a fuel injection device for an internal combustion engine that supplies high pressure fuel by injecting it into a chamber,
Fuel temperature measuring means for detecting or estimating the fuel temperature;
Fuel remaining amount measuring means for detecting or estimating the fuel remaining amount in the fuel tank;
When the fuel temperature detected or estimated by the fuel temperature measuring unit exceeds a predetermined value set in advance and the fuel remaining level detected or estimated by the fuel remaining amount measuring unit is reduced from a predetermined amount set in advance, A fuel injection device for an internal combustion engine, comprising: an accumulated pressure correction unit that corrects the accumulated pressure of the accumulation rail to be lower than when the remaining amount of fuel is greater than the predetermined amount.   The region to be corrected so as to decrease the accumulated pressure pressure includes a transition region in which a predetermined value of a preset fuel temperature is increased and divided as the fuel pressure increases from a preset remaining fuel amount. A fuel injection device for an internal combustion engine as described.   The said pressure accumulation pressure correction | amendment means reduces the fall correction amount of the said pressure accumulation pressure according to the fuel residual amount detected or estimated by the said fuel residual amount measurement means. A fuel injection device for an internal combustion engine. The high-pressure fuel pumped from the high-pressure pump is accumulated in the accumulator rail, the high-pressure fuel is distributed and supplied to the injectors installed in each cylinder of the internal combustion engine, and the injector is energized to burn each cylinder from the injector. In a fuel injection device for an internal combustion engine that supplies high pressure fuel by injecting it into a chamber,
Fuel temperature measuring means for detecting or estimating the fuel temperature;
Fuel remaining amount measuring means for detecting or estimating the fuel remaining amount in the fuel tank;
When the fuel temperature detected or estimated by the fuel temperature measuring means exceeds a predetermined value set in advance, correction is made so as to lower the pressure accumulated in the pressure accumulation rail compared to when the fuel temperature is lower than the predetermined value. And a pressure-accumulating pressure correcting means for reducing the pressure-accumulating pressure decrease correction amount in accordance with the fuel remaining amount detected or estimated by the fuel remaining-amount measuring means. .   5. The accumulator pressure correction unit increases a decrease correction amount of the accumulator pressure according to a fuel temperature detected or estimated by the fuel temperature measurement unit. 2. A fuel injection device for an internal combustion engine according to 1.   6. The accumulator pressure correction means increases the decrease rate of the accumulator pressure according to the fuel temperature detected or estimated by the fuel temperature measuring means. A fuel injection device for an internal combustion engine as described.   7. The accumulator pressure correction unit reduces the rate of decrease of the accumulator pressure in accordance with the remaining fuel amount detected or estimated by the remaining fuel amount measuring unit. The fuel-injection apparatus of the internal combustion engine as described in one.

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