JP2011127523A - Control device and control method of pressure accumulating type fuel injection device, and pressure accumulating type fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device and a control method of a pressure accumulating type fuel injection device and the pressure accumulating type fuel injection device, which maintain rail pressure in an injectable pressure or higher for a relatively long time when automatically stopping an internal combustion engine. <P>SOLUTION: This control device of the pressure accumulating type fuel injection device can perform idling stop control of the internal combustion engine. and includes an idling stop condition realization detecting means, a restarting condition realization detecting means, a fuel injection valve control means for resuming fuel injection by a fuel injection valve after a restarting condition is realized, while stopping the fuel injection by the fuel injection valve after an idling stop condition is realized, and a rail pressure control means for adjusting pressure in a common rail based on calculated target rail pressure. The rail pressure control means sets the target rail pressure after the idling stop condition is realized, to a value larger than the target rail pressure when the idling stop condition is realized. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device and control method for an accumulator fuel injection device, and an accumulator fuel injection device. In particular, the present invention relates to a control device and control method for an accumulator fuel injection device capable of executing idling stop control of an internal combustion engine, and an accumulator fuel injection device.

  2. Description of the Related Art Conventionally, as a device for injecting fuel into a cylinder of an internal combustion engine such as a diesel engine, an accumulator fuel injection device having a common rail for accumulating fuel pressurized by a high pressure pump has been used. A plurality of fuel injection valves are connected to the common rail, and energization control of each fuel injection valve is performed in a state where high-pressure fuel is supplied to each fuel injection valve, so that the internal combustion engine has various injection patterns. Fuel is injected into the cylinder.

  In such an accumulator type fuel injection device, the flow rate of the fuel supplied to the pressurizing chamber of the high pressure pump is adjusted based on a target value of the rail pressure (hereinafter referred to as “target rail pressure”), and the fuel to the common rail is adjusted. The pressure in the common rail (hereinafter referred to as “rail pressure”) is adjusted by adjusting the pumping amount, or by returning a part of the fuel pumped to the common rail to the low-pressure system, and using these controls together. Is controlled).

  By the way, in recent years, idling stop control for stopping an internal combustion engine during a temporary stop of a vehicle has been put into practical use for the purpose of improving fuel consumption and reducing exhaust gas amount and noise. In the idling stop control, when a predetermined idling stop condition is satisfied, the fuel injection is stopped and the internal combustion engine is automatically stopped. When a predetermined restart condition is satisfied, the fuel injection is restarted and the internal combustion engine is restarted.

  In a vehicle capable of executing the idling stop control of the internal combustion engine, the restartability from the automatic stop state is an element that has an important influence on the merchantability. When the internal combustion engine is, for example, a diesel engine, the compression ratio in the engine is sufficient to improve restartability from the automatic stop state of the engine, and fuel injection by the pressure accumulation type fuel injection device is possible. Is a factor. Of these two factors, whether or not the compression ratio is sufficient is a problem on the engine side, and whether or not fuel injection is possible is a problem on the accumulator fuel injection apparatus side.

  Therefore, there has been proposed a control device that can maintain a state in which fuel injection is possible and can improve the restartability of the internal combustion engine at the time of idling stop control. Specifically, an engine automatic stop / restart device for automatically stopping and restarting the engine is provided, and the engine is stopped without operating the engine automatic stop / restart device. Sometimes the rail pressure is reduced, and when the engine is stopped by operating the engine automatic stop / restart device, the rail pressure when the engine is stopped without operating the engine automatic stop / restart device is reduced. A control device is disclosed that reduces the amount of decrease in rail pressure less than the amount of decrease (see, for example, Patent Document 1).

Japanese Patent No. 3724392 (full text, all figures)

  By the way, the fuel injection valve used in the pressure accumulation type fuel injection device is sent to the fuel injection valve in addition to the back pressure relief passage for releasing the back pressure loaded on the rear end side of the nozzle needle that opens and closes the injection hole. There are structures having a leak passage for returning the fuel to the low pressure system and structures having no such leak passage.

  In the case of an accumulator fuel injection device using a fuel injection valve having a leak passage, even if the fuel injection is stopped and the pressure control valve connected to the common rail is closed, the fuel from the leak passage The rail pressure decreases due to leakage.

  On the other hand, in the case of an accumulator fuel injection device that uses a fuel injection valve that does not have a leak passage, if the fuel injection is stopped and the pressure control valve connected to the common rail is closed, the rail pressure is basically abrupt. It will never drop. However, a part of the fuel may leak to the low pressure system from the seat portion such as the pressure control valve, the back pressure control unit of the fuel injection valve, and the discharge valve of the high pressure pump. Since these seat parts are configured as a self-sealing structure in which the valve member is urged in the valve closing direction using rail pressure, the ability to maintain the rail pressure decreases as the rail pressure decreases. It has the property to do.

  Patent Document 1 is configured such that control for reducing the amount of decrease in rail pressure or maintaining the rail pressure is executed from the state of rail pressure when the engine automatic stop / restart device starts to operate. ing. Normally, the rail pressure when the automatic engine stop / restart device starts to operate is close to the target rail pressure in the idling state of the internal combustion engine. There is a risk that it will not be possible to ensure a long period of time that can be maintained.

  Accordingly, the inventors of the present invention have made diligent efforts to solve such problems by setting the target rail pressure after the predetermined idling stop condition is satisfied to a value larger than the target rail pressure when the idling stop condition is satisfied. The present invention has been found out and the present invention has been completed. That is, the present invention provides a control device and control method for an accumulator fuel injection device and an accumulator fuel injection device capable of maintaining the rail pressure at a pressure that can be injected for a relatively long time during an automatic stop of the internal combustion engine. With the goal.

  According to the present invention, there is provided a control apparatus for an accumulator fuel injection apparatus comprising: a common rail that accumulates fuel pumped by a high-pressure pump; and a fuel injection valve that is connected to the common rail and injects fuel into a cylinder of an internal combustion engine. In the control device for the accumulator fuel injection device capable of executing the idling stop control of the internal combustion engine, the idling stop condition satisfaction detecting means for detecting that the predetermined idling stop condition is satisfied, and the internal combustion engine is in the automatic stop state. Restart condition establishment detecting means for detecting that a predetermined restart condition is established for a while, and stopping fuel injection by the fuel injection valve after the idling stop condition is established, while fuel injection by the fuel injection valve after the restart condition is established Fuel injection valve control means for resuming operation and the pressure in the common rail based on the calculated target rail pressure Rail pressure control means for adjusting, and the rail pressure control means sets the target rail pressure after the idling stop condition is satisfied to a value larger than the target rail pressure when the idling stop condition is satisfied. A control device for a fuel injection device is provided to solve the above-described problems.

  Further, in configuring the control device for the pressure accumulation type fuel injection device of the present invention, it is preferable that the fuel injection valve control means stops the fuel injection after increasing the target rail pressure.

  Further, when configuring the control device for the pressure accumulating fuel injection device of the present invention, it is preferable that the fuel injection valve control means stops the fuel injection after the pressure in the common rail rises after the idling stop condition is satisfied.

  Further, in configuring the control device for the pressure accumulation type fuel injection device of the present invention, the rail pressure control means preferably corrects the value of the target rail pressure to be increased based on the temperature of the fuel.

  According to another aspect of the present invention, there is provided a pressure accumulation type fuel injection device comprising: a common rail that accumulates fuel pumped by a high-pressure pump; and a fuel injection valve that is connected to the common rail and injects fuel into a cylinder of an internal combustion engine. In the control method of the accumulator fuel injection device capable of executing the idling stop control of the internal combustion engine, when a predetermined idling stop condition is satisfied, the target rail pressure when the idling stop condition is satisfied is determined. It is a control method of the pressure accumulation type fuel injection device characterized by setting to a value larger than this.

  According to still another aspect of the present invention, there is provided an accumulator fuel injection system comprising: a common rail that stores fuel pumped by a high-pressure pump; and a fuel injection valve that is connected to the common rail and injects fuel into a cylinder of an internal combustion engine. An accumulator fuel injection apparatus comprising a control device capable of executing an idling stop control of an internal combustion engine, wherein the control device includes an idling stop condition establishment detection means for detecting that a predetermined idling stop condition is established. A restart condition establishment detecting means for detecting that a predetermined restart condition is established while the internal combustion engine is in an automatic stop state, and stopping the fuel injection by the fuel injection valve after the idling stop condition is established, Based on the fuel injection valve control means for resuming fuel injection by the fuel injection valve after establishment and the calculated target rail pressure Rail pressure control means for adjusting the pressure in the common rail, and the rail pressure control means sets the target rail pressure after the idling stop condition is satisfied to a value larger than the target rail pressure when the idling stop condition is satisfied. This is a pressure accumulation type fuel injection device.

  According to the control device and control method of the pressure accumulation type fuel injection device and the pressure accumulation type fuel injection device of the present invention, when the idling stop condition is satisfied, the target rail pressure is larger than the target rail pressure when the idling stop condition is satisfied. To rise. As a result, the time from when the fuel injection is stopped by the idling stop control until the rail pressure falls below the injectable pressure becomes longer, and the time during which the internal combustion engine can be restarted quickly can be made relatively longer.

  Further, in the control device for an accumulator fuel injection device according to the present invention, after the idling stop condition is satisfied, after the target rail pressure is increased, the fuel injection valve control means stops the fuel injection so that the rail pressure is relatively low. The fuel injection is stopped after reaching a high state. Therefore, compared with the case where fuel injection is stopped immediately when the idling stop condition is satisfied, the time until the rail pressure falls below the injectable pressure can be made relatively long.

  Further, in the control device for the pressure accumulation fuel injection device of the present invention, after the rail pressure actually increases after the idling stop condition is satisfied, the fuel injection valve control means stops the fuel injection so that the actual rail pressure is reduced. The fuel injection is stopped after confirming that the state is relatively high. Therefore, it is possible to reliably increase the time until the rail pressure falls below the injectable pressure.

  Further, in the control device for the accumulator fuel injection device of the present invention, by adjusting the target rail pressure to be increased according to the fuel temperature, the rail pressure is likely to decrease due to the decrease in the fuel density accompanying the increase in the fuel temperature. Even in this case, the time until the rail pressure falls below the injectable pressure can be maintained equally.

It is a figure which shows the structural example of the pressure accumulation type fuel injection apparatus which concerns on this embodiment. It is a figure which shows the structural example of the control apparatus of the pressure accumulation type fuel injection apparatus which concerns on this embodiment. It is a timing chart figure which shows the control method of the pressure accumulation type fuel injection device concerning this embodiment. It is a flowchart which shows the control method of the pressure accumulation type fuel injection apparatus which concerns on this embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a control device and a control method for an accumulator fuel injection device and an accumulator fuel injection device according to the present invention will be specifically described with reference to the drawings. However, such 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. Accumulated Fuel Injection Device FIG. 1 shows an overall configuration of a pressure accumulation fuel injection device 50 according to an embodiment of the present invention. The accumulator fuel injection device 50 is a device for injecting fuel into a cylinder 41 of an internal combustion engine 40 mounted on a vehicle, and includes a fuel tank 1, a low pressure pump 2, a high pressure pump 5, and flow control. A valve 8, a common rail 10, a pressure control valve 12, a fuel injection valve 13, a control device 60, and the like are provided as main elements.

  The low pressure pump 2 and the pressurization chamber 5a of the high pressure pump 5 are connected by low pressure fuel passages 18a and 18b. The pressurization chamber 5a and the common rail 10 of the high pressure pump 5 and the common rail 10 and the fuel injection valve 13 are respectively connected to the high pressure fuel passage 37. , 39. Further, return passages 30 a to 30 c for returning excess fuel not injected from the fuel injection valve 13 to the fuel tank 1 are connected to the high-pressure pump 5, the common rail 10, the fuel injection valve 13, and the like.

  A flow rate control valve 8 for adjusting the flow rate of the fuel sent to the pressurizing chamber 5a is provided in the middle of the low pressure fuel passage 18b in the high pressure pump 5. As the flow rate control valve 8, for example, an electromagnetic proportional flow rate control valve in which the stroke amount of the valve member is variable depending on the supply current value and the area of the fuel passage is adjustable is used. The flow rate control valve 8 of the present embodiment is configured as a normally open flow rate control valve in which a fuel flow path is fully opened in a non-energized state. However, it may be a normally closed flow control valve in which the fuel flow path is fully closed in a non-energized state.

  A pressure adjusting valve 14 disposed in parallel with the flow control valve 8 is provided in the fuel passage branched from the low pressure fuel passage 18 b upstream of the flow control valve 8. The pressure regulating valve 14 is connected to a return passage 30a that communicates with the fuel tank 1, and a differential pressure between the front and rear, that is, the pressure in the low-pressure fuel passage 18b and the pressure in the return passage 30a is a predetermined value. An overflow valve is used that opens when the pressure exceeds. In a state where the fuel is being pumped by the low-pressure pump 2, the pressure in the low-pressure fuel passages 18a and 18b is adjusted to be larger than the pressure in the return passage 30a by a predetermined differential pressure.

  The low pressure pump 2 sucks up the fuel in the fuel tank 1 and pumps it, and supplies the fuel to the pressurizing chamber 5a of the high pressure pump 5 through the low pressure fuel passages 18a and 18b. The low-pressure pump 2 is an in-tank electric pump provided in the fuel tank 1 and is driven by a voltage supplied from a battery. However, the low pressure pump 2 may be provided outside the fuel tank 1 or may be a gear pump that is driven by the power of the internal combustion engine 40.

  The high-pressure pump 5 pressurizes fuel introduced into the pressurizing chamber 5 a via the fuel intake valve 6 by the low-pressure pump 2 by the plunger 7, and supplies high-pressure fuel to the common rail via the fuel discharge valve 9 and the high-pressure fuel passage 37. 10 to pump. The fuel discharge valve 9 has a self-sealing structure in which the sealing performance is enhanced as the rail pressure located on the discharge side is higher.

  The cam 15 that drives the high-pressure pump 5 is fixed to a cam shaft that is connected to a drive shaft of the internal combustion engine 40 via a gear. The high pressure pump 5 shown in FIG. 1 includes two plungers 7, the two plungers 7 are pushed up by cams 15, and the fuel is pressurized in the two pressurizing chambers 5 a to increase the pressure to the common rail 10. The fuel is pumped. The high-pressure pump 5 has a fuel-lubricated configuration in which fuel for injection is used as lubricating oil, and the fuel sent into the high-pressure pump 5 through the low-pressure fuel passage 18a once flows into the cam chamber 16 and from there. Further, it is sent to the pressurizing chamber 5a through the low-pressure fuel passage 18b.

  The high pressure pump 5 shown in FIG. The sensor signal St of the temperature sensor 25 is sent to the control device 60, and the fuel temperature Tq flowing through the low pressure fuel passage 18b is detected based on the sensor signal St. However, the temperature sensor for detecting the fuel temperature may be provided at any location in the fuel passage in the accumulator fuel injection device 50.

  The common rail 10 accumulates high-pressure fuel pressurized by the high-pressure pump 5 and supplies the fuel to the fuel injection valve 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. The sensor signal Sp of the rail pressure sensor 21 is sent to the control device 60, and the rail pressure Pr is detected based on the sensor signal Sp.

  As the pressure control valve 12, for example, an electromagnetic proportional control valve in which the stroke amount of the valve member is variable depending on the supply current value and the area of the fuel passage is adjustable is used. The pressure control valve 12 of the present embodiment is configured as a normally open pressure control valve in which the fuel flow path is fully opened in a non-energized state. The normally open type pressure control valve is the sum of the biasing force of the spring that biases the valve member for opening and closing the fuel passage in the valve opening direction and the rail pressure, and the force that biases the valve member in the valve closing direction. Opens when the rate is above.

  The fuel injection valve 13 includes a nozzle body provided with an injection hole and a nozzle needle that opens and closes the injection hole by advancing and retreating. The fuel injection valve 13 closes the injection hole by applying a back pressure to the rear end side of the nozzle needle, while opening the injection hole by releasing the loaded back pressure. When the rail pressure is equal to or higher than the injectable pressure, normal fuel injection by the fuel injection valve 13 is possible.

  As the fuel injection valve 13, an electrostrictive piezo injector provided with a piezo element as back pressure control means, or an electromagnetic control type magnet injector provided with an electromagnetic solenoid as back pressure control means is used. In the present embodiment, a fuel injection valve having a leak passage for leaking fuel from a sliding portion such as a nozzle needle or a valve piston to the return passage 30c is used in addition to a passage for releasing back pressure. Yes. Therefore, even when the injection is stopped and the pressure control valve 12 is closed, the rail pressure is likely to decrease due to fuel leak from the leak passage.

  However, the pressure-accumulation fuel injection device does not have a leak passage in the fuel injection valve, and the pressure-accumulation fuel injection is configured such that the rail pressure is not easily lowered when the fuel injection is stopped and the pressure control valve 12 is closed. The present invention can be applied even to an apparatus.

  In the pressure accumulation type fuel injection device 50 configured as described above, the high pressure fuel pumped from the high pressure pump 5 flows through the discharge valve of the high pressure pump 50, the pressure control valve 12, and the back pressure control unit of the fuel injection valve 13. It exists between the area and the area where low-pressure fuel flows. The seat portions of these valves have a self-sealing structure in which the sealing performance is enhanced as the rail pressure increases. Therefore, even when the fuel injection is stopped and the pressure control valve 12 is closed, depending on the rail pressure, the fuel tends to leak to the low pressure side through these seat portions.

2. Control Device FIG. 2 shows a configuration example in which a portion related to idling stop control in the control device 60 of the accumulator fuel injection device 50 of the present embodiment is represented by a functional block.
The control device 60 includes an idling stop condition establishment detection means 61, a restart condition establishment detection means 62, a target rail pressure calculation means 64, a rail pressure detection means 65, a flow control valve control means 66, and a pressure control valve. Control means 67, fuel injection valve control means 68, and the like are provided. The control device 60 is configured around a microcomputer having a known configuration, and each unit is realized by executing a program by the microcomputer.

  Further, the control device 60 detects the rail pressure sensor 21 and the temperature sensor 25, a rotational speed sensor that detects the engine rotational speed Ne, a vehicle speed sensor that detects the vehicle speed V provided in the vehicle, and an accelerator pedal operation amount Acc. It is configured to be able to read signals from various switches and sensors such as an accelerator sensor and a brake sensor for detecting an operation amount Brk of the brake pedal. Further, the control device 60 is provided with a RAM (Random Access Memory) (not shown) for storing calculation results and detection results at each unit.

  Among these, the rail pressure detecting means 65 continuously reads the sensor value Sp of the rail pressure sensor 21 to obtain the rail pressure Pr.

  When the idling stop condition establishment detection means 61 detects the establishment of a predetermined idling stop condition, it transmits an idling stop condition establishment signal to the fuel injection valve control means 66, the flow rate control valve control means 67, and the pressure control valve control means 68. . Further, the restart condition establishment detection unit 62 detects the establishment of a predetermined restart condition while the internal combustion engine 40 is in the automatic stop state, and then restarts the fuel injection valve control unit 66 and the pressure control valve control unit 68. A start condition satisfaction signal is transmitted.

  The idling stop condition is, for example, that the engine switch Sw is on, the detection position Sg of the gear sensor is neutral, the detection position Sb of the brake pedal sensor is stepped on, and the engine speed Ne is predetermined. However, the present invention is not limited to this. However, the present invention is not limited to this.

  The restart condition includes several conditions such as that the detection position Sg of the gear sensor is released from the neutral state and the accelerator pedal Acc is depressed while the internal combustion engine 40 is in the automatic stop state. This can be done, but is not limited to this.

  The flow control valve control means 66 and the pressure control valve control means 67 basically perform feedback control of the flow control valve 8 or the pressure control valve 12 so that the rail pressure Pr becomes the target rail pressure Ptgt. Specifically, the flow control valve control means 66 controls the flow rate of the fuel supplied to the pressurizing chamber 5a of the high pressure pump 5 by adjusting the opening degree of the flow control valve 8, and from the high pressure pump 5 to the common rail 10. The rail pressure Pr is adjusted by changing the flow rate of the high-pressure fuel to be pumped. Further, the pressure control valve control means 67 controls the flow rate of the fuel discharged from the common rail 10 to the return passage 30b by adjusting the opening of the pressure control valve 12, thereby adjusting the rail pressure Pr.

  Whether the rail pressure Pr is controlled by the flow rate control valve control means 66, the pressure control valve control means 67, or by using the two control units in combination depends on the running state of the vehicle and the operation of the internal combustion engine 40. It is divided according to the state.

  However, it is set so that the rail pressure Pr is controlled by the pressure control valve control means 67 at least after the idling stop condition is satisfied and until the restart condition is satisfied. Specifically, when the idling stop condition is satisfied, the flow control valve 8 of the present embodiment having the normally open configuration is cut off and fully opened, and the pressure control valve 67 by the pressure control valve control means 67. 12 feedback control is started.

  Further, while the internal combustion engine 40 is stopped due to the establishment of the idling stop condition, a current having a value obtained from the target rail pressure Ptgt may be continuously supplied. When Pr is less than the injectable pressure Pr_inj, energization of the pressure control valve 12 may simply waste the battery. Therefore, when the rail pressure Pr is lower than the injectable pressure Pr_inj, the feedback control of the pressure control valve 12 with the target rail pressure Ptgt is interrupted, and the energization current value is set to zero or set to a very small value. Is preferred.

The target rail pressure calculating means 64 calculates the target rail pressure Ptgt based on the engine speed Ne, the accelerator operation amount Acc, and the like in the normal operation state of the internal combustion engine 40.
Moreover, the target rail pressure calculating means 64 will raise a target rail pressure toward predetermined | prescribed target holding rail pressure Ptgt_high, if an idling stop condition satisfaction signal is received. Thus, feedback control of the energization amount of the pressure control valve 12 is performed so that the rail pressure Pr rises toward the target holding rail pressure Ptgt_high after the idling stop condition is satisfied and until the restart condition is satisfied.

  The target holding rail pressure Ptgt_high is a value at which the rail pressure Pr can be maintained at the injection pressure Pr_inj or higher even when the internal combustion engine 40 is automatically stopped for a relatively long time, and while the internal combustion engine 40 is in the automatic stop state. It is determined in consideration of the amount of rail pressure drop. If a relatively large value is set as the target holding rail pressure Ptgt_high, fuel injection can be stopped after the rail pressure Pr is further increased, so the rail pressure Pr is equal to or higher than the injectable pressure Pr_inj. A longer sustainable time can be secured.

  However, if the target holding rail pressure Ptgt_high is set to an excessively large value, the rail pressure Pr may exceed the allowable pressure of the accumulator fuel injection device 50. Therefore, the target holding rail pressure Ptgt_high is considered in consideration of the load generated in the fuel high pressure system. Is preferably determined.

  The target holding rail pressure Ptgt_high can be a fixed value, for example. If the target holding rail pressure Ptgt_high is a fixed value, the target holding rail pressure Ptgt_high can be quickly switched to when the idling stop condition is satisfied. However, the target holding rail pressure Ptgt_high is not limited to a fixed value. For example, a predetermined offset value can be added to the target rail pressure Ptgt when the idling stop condition is satisfied to obtain the target holding rail pressure.

  By setting the target rail pressure Ptgt after the idling stop condition is satisfied to be larger than when the idling stop condition is satisfied, the current value supplied to the pressure control valve 12 increases compared to when the idling stop condition is satisfied, and the internal combustion engine 40 is stopped. In the meantime, the rail pressure Pr rises once. Therefore, compared to the case where fuel injection is stopped without increasing the target rail pressure Ptgt, the time during which the rail pressure Pr can be maintained at the injectable pressure Pr_inj or more can be lengthened.

  The target rail pressure calculation means 64 can be switched so as to change the target rail pressure Ptgt stepwise when the idling stop condition is satisfied. If the target rail pressure Ptgt is switched so as to change in steps, the pressure control valve 12 can be instantaneously closed and the rail pressure Pr can be instantaneously increased.

  However, if the target rail pressure Ptgt is switched so as to change in steps, the rail pressure Pr temporarily temporarily increases immediately after the idling stop condition is satisfied, and there is a possibility that a great load is applied to the fuel high pressure system. In order to prevent such an excessive increase in the rail pressure Pr, the target rail pressure Ptgt may be gradually increased. If the target rail pressure Ptgt is gradually increased, the rail pressure Pr can be gradually increased, so that a large load is prevented from being applied to the fuel high pressure system.

  Further, the target holding rail pressure Ptgt_high may be configured to be set according to the fuel temperature Tq. When the fuel temperature Tq is increased, the fuel density is decreased, and the fuel is liable to leak to the low pressure side through a minute gap existing in the fuel high pressure system, and the rail pressure Pr is likely to be decreased. Therefore, the rail pressure Pr may fall below the injectable pressure Pr_inj earlier than expected. Therefore, it is preferable to set the target holding rail pressure Ptgt_high to increase as the fuel temperature Tq increases.

  The fuel temperature Tq can be calculated based on the sensor signal St of the temperature sensor 25, but can also be estimated based on the exhaust gas temperature Tg, the cooling water temperature Tw, the outside air temperature Ta, the operating state of the internal combustion engine, and the like. The fuel temperature Tq may be estimated by taking into account the exhaust gas temperature Tg, the cooling water temperature Tw, the outside air temperature Ta, the operating state of the internal combustion engine, and the like to the sensor signal St of the temperature sensor 25.

  The fuel injection valve control means 68 calculates a target fuel injection amount Qtgt based on the engine speed Ne, the accelerator operation amount Acc, and the like, and generates a control signal for the fuel injection valve 13 corresponding to the target fuel injection amount Qtgt. A control signal is transmitted to the injection valve 13.

  Further, in this embodiment, when the fuel injection valve control means 68 receives the idling stop condition satisfaction signal, the target fuel injection amount until the difference ΔPr between the rail pressure Pr and the target holding rail pressure Ptgt_high becomes less than the predetermined value ΔPr0. The injection control based on Qtgt is continued, and the fuel injection is stopped when the rail pressure difference ΔPr becomes less than a predetermined value ΔPr0. By stopping the fuel injection in this way when the idling stop condition is satisfied, it is possible to stop the fuel injection by determining that the rail pressure Pr does not increase excessively while the rail pressure Pr is reliably increased.

  The timing for stopping the fuel injection is not limited to the example described above. The fuel injection may be stopped when the rail pressure Pr actually exceeds the target holding rail pressure Ptgt_high. Further, for example, the fuel injection can be stopped when the time after the idling stop condition is satisfied reaches a predetermined time.

  When the fuel injection valve control means 68 receives the restart condition establishment signal, the fuel injection valve control means 68 transmits a control signal to the fuel injection valve 13 to restart fuel injection.

3. Next, an example of the control executed by the control device 60 of the above-described pressure-accumulation fuel injection device 50 will be described in detail based on the time chart of FIG. 3 and the control flow of FIG. . In FIG. 3, the change over time of the target rail pressure Ptgt, the rail pressure Pr, the engine speed Ne, and the energization current value according to the control method of the present embodiment is indicated by solid lines, and each of the control methods according to the control method that does not increase the target rail pressure. An example of the change over time is shown by a broken line.

  In the control flow of FIG. 4, it is first determined in step S11 whether or not a predetermined idling stop condition is satisfied (period t0 to t1 in FIG. 3). In the period from t0 to t1 in FIG. 3, the energization current value to the pressure control valve 12 is feedback-controlled according to the target rail pressure Ptgt, and control is performed so that the rail pressure Pr becomes the target rail pressure Ptgt. Yes.

  When the idling stop condition is satisfied, the process proceeds to step S12, and the target rail pressure Ptgt is increased toward the target holding rail pressure Ptgt_high that is larger than the target rail pressure when the idling stop condition is satisfied (t1 in FIG. 3). As a result, the energization current value to the pressure control valve 12 is controlled so that the rail pressure Pr becomes the target rail pressure Ptgt. Thereafter, the process proceeds to step S13, and the rail pressure Pr is detected. In step S14, it is determined whether or not the difference ΔPr between the rail pressure Pr and the target holding rail pressure Ptgt_high is less than a predetermined value ΔPr0 (from t1 in FIG. 3). t2 period).

  When the difference ΔPr between the rail pressure Pr and the target holding rail pressure Ptgt_high becomes less than the predetermined value ΔPr0, the process proceeds to step S15, and fuel injection to the internal combustion engine 40 is stopped (t2 in FIG. 3). Even if the fuel injection is stopped, since the fuel is supplied from the high pressure pump 5 to the common rail 10 until the engine speed Ne becomes zero, the rail pressure Pr rises for a while and then starts to decrease.

  After the fuel injection is stopped, it is determined in step S16 whether or not a restart condition is satisfied (period t2 to t3 in FIG. 3). When it is determined that the restart condition is satisfied, the process proceeds to step S17, and after detecting the rail pressure Pr, it is determined in step S18 whether the rail pressure Pr is equal to or higher than the injectable pressure Pr_inj (t3 in FIG. 3). Period). When the rail pressure Pr is equal to or higher than the injectable pressure Pr_inj, the process proceeds to step S19 to restart the fuel injection. At this time, fuel injection is basically performed after the inside of the cylinder of the internal combustion engine 40 is compressed using an auxiliary device such as a starter. If the inside of the cylinder is in a compressed state, the auxiliary device is used. The fuel injection can be restarted promptly without using.

  On the other hand, when the rail pressure Pr is less than the injectable pressure Pr_inj, the drive shaft of the internal combustion engine 40 is rotated by an auxiliary device such as a starter, and fuel injection is resumed until the rail pressure Pr becomes equal to or higher than the injectable pressure P_inj. Wait and return to step S17. When the rail pressure Pr becomes equal to or higher than the injectable pressure Pr_inj, the fuel injection is restarted in step S19.

  As described above, in the control method of the pressure accumulation fuel injection device according to the present embodiment, after the idling stop condition is satisfied, the fuel injection is stopped after the target rail pressure Ptgt is made larger than when the idling stop condition is satisfied. Therefore, the rail pressure Pr is once increased before the fuel injection is stopped, and a long time from when the fuel injection is stopped until the rail pressure Pr falls below the injectable pressure Pr_inj is secured. In particular, in this embodiment, since the fuel injection is stopped after the difference ΔPr between the rail pressure Pr and the target holding rail pressure Ptgt_high reaches a predetermined value ΔPr0, the rail pressure Pr is reliably increased, and the rail pressure Pr is The time maintained above the injectable pressure Pr_inj can be reliably lengthened.

  In contrast, in the control method in which the target rail pressure indicated by the broken line in FIG. 3 is not increased, the rail pressure Pr gradually decreases with the rail pressure Pr at the time t1 when the idling stop condition is satisfied as a reference. Therefore, the rail pressure Pr becomes lower than the injectable pressure Pr_inj at a relatively early time t4 ′.

  In this embodiment, since the rail pressure Pr is once increased after the idling stop condition is established, the sealing performance at the seat portions of various valves configured as a self-sealing structure is improved, and the rail pressure Pr is further reduced. Can be easily suppressed.

The control device and control method of the accumulator fuel injection device and the accumulator fuel injector of the present embodiment described above can be arbitrarily changed within the scope of the present invention.
For example, the rail pressure Pr may be temporarily increased by controlling the flow control valve 8 by the flow control valve control means 67 after the idling stop condition is satisfied. Specifically, when the idling stop condition is satisfied, the pressure control valve 12 is maintained in the closed state, and the opening degree of the flow control valve 8 is made larger than the opening degree when the idling stop condition is satisfied, so that the rail pressure You may make it raise Pr.

1: Fuel tank, 2: Low pressure pump, 5: High pressure pump, 5a: Pressurization chamber, 6: Fuel intake valve, 7: Plunger, 8: Flow control valve, 9: Fuel discharge valve, 10: Common rail, 12: Pressure Control valve, 13: Fuel injection valve, 14: Overflow valve, 15: Cam, 18a-18d: Fuel supply passage, 21: Pressure sensor, 30a-30c: Return passage, 37, 39: High pressure fuel passage, 40: Internal combustion engine , 41: cylinder, 50: accumulator fuel injection device, 60: control device, 61: idling stop condition establishment detection means, 62: restart condition establishment detection means, 64: target rail pressure calculation means, 65: rail pressure detection means , 66: flow control valve control means, 67: pressure control valve control means, 68: fuel injection valve control means

Claims (6)

A control device for an accumulator fuel injection device comprising: a common rail that accumulates fuel pumped by a high-pressure pump; and a fuel injection valve that is connected to the common rail and injects the fuel into a cylinder of an internal combustion engine, In a control device for an accumulator fuel injection device capable of executing idling stop control of an internal combustion engine,
An idling stop condition establishment detecting means for detecting that a predetermined idling stop condition is established;
Restart condition establishment detection means for detecting that a predetermined restart condition is established while the internal combustion engine is in an automatic stop state;
Fuel injection valve control means for stopping fuel injection by the fuel injection valve after the idling stop condition is satisfied, and restarting fuel injection by the fuel injection valve after the restart condition is satisfied;
Rail pressure control means for adjusting the pressure in the common rail based on the calculated target rail pressure, and
The rail pressure control means sets the target rail pressure after the idling stop condition is satisfied to a value larger than the target rail pressure when the idling stop condition is satisfied.   The said fuel injection valve control means stops the said fuel injection after making the said target rail pressure large, The control apparatus of the pressure accumulation type fuel injection apparatus of Claim 1 characterized by the above-mentioned.   3. The control of an accumulator fuel injection device according to claim 1, wherein the fuel injection valve control unit stops the fuel injection after the pressure in the common rail rises after the idling stop condition is satisfied. 4. apparatus.   The said rail pressure control means correct | amends the value of the said target rail pressure made large based on the temperature of the said fuel, Control of the pressure accumulation type fuel injection apparatus as described in any one of Claims 1-3 characterized by the above-mentioned. apparatus. A control method for an accumulator fuel injection apparatus comprising: a common rail that accumulates fuel pumped by a high-pressure pump; and a fuel injection valve that is connected to the common rail and injects the fuel into a cylinder of an internal combustion engine, In a control method of an accumulator fuel injection device capable of executing idling stop control of an internal combustion engine,
When the predetermined idling stop condition is satisfied, the target rail pressure is set to a value larger than the target rail pressure when the idling stop condition is satisfied. A pressure accumulating fuel injection apparatus comprising: a common rail that accumulates fuel pumped by a high-pressure pump; and a fuel injection valve that is connected to the common rail and injects the fuel into a cylinder of the internal combustion engine. In an accumulator fuel injection device equipped with a control device capable of performing idling stop control,
The controller is
An idling stop condition establishment detecting means for detecting that a predetermined idling stop condition is established;
Restart condition establishment detection means for detecting that a predetermined restart condition is established while the internal combustion engine is in an automatic stop state;
Fuel injection valve control means for stopping fuel injection by the fuel injection valve after the idling stop condition is satisfied, and restarting fuel injection by the fuel injection valve after the restart condition is satisfied;
Rail pressure control means for adjusting the pressure in the common rail based on the calculated target rail pressure, and
The pressure accumulation type fuel injection device, wherein the rail pressure control means sets the target rail pressure after the idling stop condition is satisfied to a value larger than the target rail pressure when the idling stop condition is satisfied.

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