JP5477899B2 - Control device and control method for accumulator fuel injector and accumulator fuel injector - Google Patents

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, a control device and control method for an accumulator type fuel injection device having a normally open type pressure control valve and a fuel injection valve having a leak passage and capable of performing idling stop control of an internal combustion engine, and an accumulator type fuel injection device About.

  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 fuel injection device, the common rail pressure (hereinafter referred to as “rail pressure”) greatly affects the fuel injection characteristics. As a rail pressure control method, the opening of the pressure control valve connected to the common rail is adjusted according to the target value of the rail pressure (hereinafter referred to as “target rail pressure”), and the rail pressure is discharged to the low pressure side. There is a method of controlling rail pressure by adjusting the flow rate of fuel.

  As this pressure control valve, a valve member that opens and closes the fuel flow path is urged in the valve opening direction by the urging force of a spring and has a normally open type structure in which the fuel flow path is opened in a non-energized state. is there. Generally, the rail pressure is reduced when the internal combustion engine is stopped, but if a pressure control valve having a normally open type structure is used, the rail pressure can be reduced without performing energization control when the internal combustion engine is stopped. it can.

  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)

  The control device described in Patent Document 1 is provided with a normally closed type pressure reducing valve connected to a common rail. When the ignition switch is turned off and the internal combustion engine is stopped, the pressure reducing valve is driven to lower the rail pressure. On the other hand, when the internal combustion engine is stopped by the idling stop control, the pressure reducing valve is closed without driving the pressure reducing valve.

  On the other hand, when a normally open type pressure control valve is used, when the internal combustion engine is stopped by idling stop control, it is necessary to energize the pressure control valve and close the pressure control valve.

  Here, as a fuel injection valve provided in the accumulator fuel injection device, the fuel injection valve is sent to the fuel injection valve other than 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 is a fuel injection valve having a leak passage for returning a part of fuel to the low pressure side. When such a fuel injection valve is used, the fuel leaks to the low pressure side through the leak passage despite the various valves provided in the region where the high pressure fuel is held closed. Immediately after the execution of the automatic stop control of the internal combustion engine, the rail pressure falls below the injectable pressure.

  In the pressure accumulation type fuel injection device in which the fuel injection valve is provided with the leak passage in this way, when a normally open type pressure control valve is used, if the control for maintaining the rail pressure during the idling stop control is performed, The battery can be wasted. Therefore, in a pressure accumulation type fuel injection device in which a leak passage is provided in the fuel injection valve, when a normally open type pressure control valve is used, automatic stop control of the internal combustion engine is executed from the viewpoint of reducing battery consumption. Simultaneously with the start, the energization current value to the pressure control valve is switched to a very small value, or the energization to the pressure control valve is stopped.

  When the energization current value to the pressure control valve is switched to a very small value or the energization is stopped, the rail pressure rapidly decreases to the atmospheric pressure equivalent immediately after the start of the automatic stop control of the internal combustion engine. Therefore, after the fuel injection is stopped by the automatic stop control of the internal combustion engine, the rail pressure falls below the injectable pressure for a short time until the engine speed becomes zero.

  However, during the operation of the vehicle, for example, when the signal turns blue immediately after the vehicle is temporarily stopped by waiting for a signal or the like, and the vehicle is started, the idling stop condition is satisfied and the automatic stop control of the internal combustion engine is started. Later, the restart condition may be satisfied immediately. In such a case, if the energization current value to the pressure control valve is switched to a very small value simultaneously with the start of execution of the automatic stop control of the internal combustion engine, or the energization to the pressure control valve is stopped, the internal combustion engine is still The fuel injection cannot be resumed because the rail pressure is below the injectable pressure despite the rotation. As a result, after the internal combustion engine is stopped, it is necessary to raise the lowered rail pressure again to be higher than the injectable pressure and to restart the fuel injection after the inside of the cylinder of the internal combustion engine is compressed by a starter or the like. There is a problem that it takes time to restart the internal combustion engine.

  Therefore, the inventors of the present invention have made diligent efforts to maintain the current value to the pressure control valve at a value equal to or higher than the current value at the time when the idling stop condition is satisfied until a predetermined time elapses after the idling stop condition is satisfied. The inventors have found that such a problem can be solved by lowering the energization current value to the pressure control valve to less than the energization current value when the idling stop condition is satisfied after a predetermined time has elapsed, and the present invention has been completed. That is, the present invention reduces the battery consumption in the idling stop control, while the restart condition is established between the start of the execution of the automatic stop control of the internal combustion engine and the complete stop of the internal combustion engine. An object of the present invention is to provide a control device and control method for an accumulator fuel injection device that can quickly restart an internal combustion engine, and an accumulator fuel injection device.

According to the present invention, a common rail that stores fuel pumped by a high-pressure pump, a pressure control valve that has a normally open structure in which a fuel flow path is opened in a non-energized state, and adjusts the pressure in the common rail; A fuel injection valve that is connected to the common rail and injects fuel into the cylinder of the internal combustion engine, and the fuel injection valve releases the back pressure applied to the rear end side of the nozzle needle that opens and closes the injection hole. In addition to the pressure relief passage, a control device for an accumulator fuel injection device having a leak passage for returning part of the fuel sent to the fuel injection valve to the low pressure side, and capable of executing idling stop control of the internal combustion engine In the control device of the fuel injection device, idling stop condition satisfaction detecting means for detecting that a predetermined idling stop condition is satisfied, and the internal combustion engine is in an 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 when the idling stop condition is established, while fuel injection by the fuel injection valve when the restart condition is established The fuel injection valve control means for resuming the operation, and until the predetermined time has elapsed after the idling stop condition is satisfied, the energizing current value to the pressure control valve is maintained to be equal to or higher than the energizing current value when the idling stop condition is satisfied, Pressure control valve control means for lowering the energization current value to the pressure control valve to less than the energization current value when the idling stop condition is satisfied after the predetermined time has elapsed, and the energization current value to the pressure control valve at the predetermined time is in the case of increasing, the pressure control valve control means in the accumulator fuel injection apparatus according to claim Rukoto gradually increasing the energization current value Control device is provided, it is possible to solve the problems described above.

  Further, when the energizing current value is gradually increased when configuring the control device for the accumulator fuel injection device of the present invention, the pressure control valve control means sets the gradient of the change in the energizing current value to the rotational speed of the internal combustion engine. It is preferable to determine accordingly.

  Further, in configuring the control device for the accumulator fuel injection device of the present invention, it is preferable that the pressure control valve control means determines the value of the energization current to the pressure control valve at a predetermined time according to the fuel temperature.

  Further, in configuring the control device for an accumulator fuel injection device of the present invention, the predetermined time is preferably a time from when the fuel injection is stopped until the rotational speed of the internal combustion engine is reduced to a predetermined threshold value.

Another aspect of the present invention has a common rail that accumulates fuel pumped by a high-pressure pump and a normally open structure in which a fuel flow path is opened in a non-energized state, and adjusts the pressure in the common rail. A pressure control valve and a fuel injection valve that is connected to a common rail and injects fuel into a cylinder of the internal combustion engine, and the fuel injection valve applies a back pressure applied to the rear end side of the nozzle needle that opens and closes the injection hole. A control method for an accumulator fuel injection device having a leak passage for returning a part of the fuel sent to the fuel injection valve to the low pressure side in addition to the back pressure relief passage for releasing, and performing idling stop control of the internal combustion engine In a control method for a pressure-accumulation fuel injection device that is possible, the current value to be supplied to the pressure control valve is idled until a predetermined time elapses after a predetermined idling stop condition is satisfied. While maintaining the above electric current value at the time of establishment stop condition, after a predetermined time has elapsed, to reduce the electric current value to the pressure control valve to less than the energization current value during establishment idling stop condition, the pressure control valve in a predetermined time in the case of increasing the applied current value, a method of controlling accumulator fuel injection device according to claim Rukoto gradually increasing the energization current.

Still another aspect of the present invention has a common rail that accumulates fuel pumped by a high-pressure pump and a normally open structure in which a fuel flow path is opened in a non-energized state to adjust the pressure in the common rail. A back pressure applied to a rear end side of a nozzle needle that opens and closes an injection hole, and a pressure injection valve that is connected to a common rail and injects fuel into a cylinder of the internal combustion engine. A pressure accumulation type fuel injection apparatus having a leak passage for returning a part of the fuel sent to the fuel injection valve to the low pressure side in addition to the back pressure relief passage for releasing the engine, and capable of executing idling stop control of the internal combustion engine In the pressure-accumulation fuel injection device provided with the control device, the control device includes an idling stop condition establishment detection unit that detects 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, and stopping the fuel injection by the fuel injection valve when the idling stop condition is established, while the restart condition is established The fuel injection valve control means for resuming fuel injection by the fuel injection valve at the time, and the energization current value when the idling stop condition is satisfied until the predetermined time elapses after the idling stop condition is satisfied Pressure control valve control means for reducing the energization current value to the pressure control valve to less than the energization current value when the idling stop condition is satisfied after a predetermined time has elapsed, and maintaining pressure control for a predetermined time in the case of increasing the energizing current to the valve, the pressure control valve control means and said Rukoto gradually increasing the energization current value That is a pressure accumulation type fuel injection system.

  According to the control device and control method for an accumulator fuel injection device and the accumulator fuel injector of the present invention, the current value supplied to the pressure control valve is idle until a predetermined time elapses after the idling stop condition is satisfied. The energization current value to the pressure control valve is maintained to be equal to or higher than the energization current value at the time when the stop condition is satisfied, and after a predetermined time has elapsed, the energization current value to the pressure control valve is reduced to less than the energization current value at the time when the idling stop condition is satisfied. Therefore, when the restart condition is satisfied before the internal combustion engine is completely stopped, the fuel injection can be restarted quickly. On the other hand, after the internal combustion engine is stopped, the amount of current supplied to the pressure control valve is reduced. Suppression is achieved.

  Further, in the control device for an accumulator fuel injection device according to the present invention, when the energizing current value to the pressure control valve for a predetermined time is increased, the pressure control valve control means gradually increases the energizing current value, thereby idling. The pressure control valve can be closed while letting some of the fuel pumped to the common rail to the low pressure side after the stop condition is satisfied. As a result, the rail pressure can be prevented from significantly increasing after the execution of the automatic stop control of the internal combustion engine.

  Further, in the control device for the accumulator type fuel injection device of the present invention, when the energization current value is gradually increased, the pressure control valve control means determines the gradient of the energization current value according to the rotational speed of the internal combustion engine. A part of the fuel in the common rail can be released to the low pressure side while considering the flow rate of the fuel pumped to the common rail after the idling stop condition is satisfied. Therefore, it is possible to suppress the rail pressure from significantly increasing while ensuring the rail pressure to be higher than the injectable pressure.

  Further, in the control device for the accumulator fuel injection device according to the present invention, the pressure control valve control means determines the current value to be supplied to the pressure control valve at a predetermined time according to the fuel temperature, thereby increasing the temperature of the fuel. When the rail pressure tends to decrease due to the decrease in density, the value of the current supplied to the pressure control valve can be increased to maintain the rail pressure appropriately.

  Further, in the control device for an accumulator fuel injection device according to the present invention, the predetermined time is a time from when the fuel injection is stopped until the rotational speed of the internal combustion engine decreases to a predetermined threshold value. When the restart condition is satisfied after the start of the stop control and before the internal combustion engine is completely stopped, the internal combustion engine can be restarted quickly.

It is a figure which shows the structural example of the pressure accumulation type fuel-injection apparatus concerning embodiment of this invention. It is a figure which shows the structural example of the control apparatus of a pressure accumulation type fuel injection apparatus. It is a timing chart figure which shows the conventional control method. It is a timing chart figure which shows the control method concerning embodiment of this invention. It is a control flow which shows the control method concerning embodiment of this invention.

  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, 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. Accumulated Fuel Injection Device FIG. 1 shows an overall configuration of an accumulator 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 pressurizing chamber 5a of the high pressure pump 5 are connected by low pressure fuel passages 18a and 18b. The pressurizing chamber 5a of the high pressure pump 5 and the common rail 10, and the common rail 10 and the fuel injection valve 13 are respectively high pressure fuel. The passages 37 and 39 are connected. Further, return passages 30 a to 30 c that return 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 the differential pressure between the front and rear, that is, the pressure difference between the pressure in the low-pressure fuel passage 18b and the pressure in the return passage 30a has a predetermined value. An overflow valve is used that opens when exceeded. 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 check valve structure in which the sealing performance is improved 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, in addition to the passage for releasing the back pressure, a fuel injection valve having a leak passage for leaking fuel to the return passage 30c from a sliding portion such as a nozzle needle or a valve piston is used. 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.

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 fuel injection valve control means 68, and a flow rate control valve. Control means 66, pressure control valve control means 67, 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.

  When the idling stop condition establishment detecting 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 68, the flow rate control valve control means 66, and the pressure control valve control means 67. . Further, the restart condition establishment detecting means 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 means 68 and the pressure control valve control means 67. 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 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, the fuel injection valve control means 68 stops the fuel injection upon receiving the idling stop condition satisfaction signal, and transmits the control signal to the fuel injection valve 13 upon receiving the restart condition satisfaction signal to resume the fuel injection. Let

  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. Further, the rail pressure detecting means 65 continuously reads the sensor value Sp of the rail pressure sensor 21 and obtains the rail pressure Pr.

  The flow control valve control means 66 and the pressure control valve control means 67 basically execute energization 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 the two control means 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.

  Further, the flow control valve control means 66 cuts off the power supply to the flow control valve 8 when receiving the idling stop condition establishment signal. Since the flow control valve 8 of the present embodiment has a normally open configuration, the flow control valve 8 is fully opened when the power is turned off.

  In addition, when the pressure control valve control means 67 receives the idling stop condition establishment signal, the pressure control valve control means 67 maintains the conduction current value to the pressure control valve 12 at or above the conduction current value A_base when the idling stop condition is established for a predetermined time tw. I do. By executing such control, the fuel pressure-fed by the high-pressure pump 5 is accumulated in the common rail 10 until the internal combustion engine 40 is completely stopped, and a sudden drop in the rail pressure Pr can be prevented. .

  The holding current value A_high supplied to the pressure control valve 12 during the predetermined time tw is set to, for example, a predetermined value stored in advance in the RAM, or a predetermined offset amount is added to the energization current value A_base when the idling stop condition is satisfied. Or can be set to the value obtained. This holding current value A_high is a decrease amount of the rail pressure Pr immediately after the start of the automatic stop control so that the rail pressure Pr is maintained at the injection possible pressure Pr_inj or more for a predetermined time tw after the start of the automatic stop control of the internal combustion engine 40. It is determined in consideration of etc.

  The holding current value A_high may be a value of the energization current value A_base when the idling stop condition is satisfied, or may be a value larger than the energization current value A_base when the idling stop condition is satisfied. The larger the holding current value A_high, the higher the maximum value of the rail pressure Pr that can be held at the start of execution of the automatic stop control of the internal combustion engine 40. However, if the holding current value A_high is excessively increased, the rail pressure Pr becomes remarkably high. Since the load on the high-pressure fuel system including the common rail 10 and the high-pressure pump 5 increases and it is preferable to set in consideration of the change in the rail pressure Pr.

  If the energizing current value to the pressure control valve 12 is step-changed from the energizing current value A_base when the idling stop condition is satisfied to the holding current value A_high, the rail pressure Pr_high corresponding to the holding current value A_high can be instantaneously reached. it can. However, if the energization current value to the pressure control valve 12 is changed in steps, the rail pressure Pr may increase excessively immediately after the execution of the automatic stop control of the internal combustion engine 40 is started. In this case, the current value supplied to the pressure control valve 12 may be gradually increased from the current value A_base when the idling stop condition is satisfied to the holding current value A_high. If the energization current value is gradually increased, the pressure control valve 12 can be closed while returning a part of the fuel in the common rail 10 to the low pressure side, and the rail pressure is prevented from instantaneously increasing excessively. This makes it difficult for the fuel high pressure system to be loaded.

  The slope of the change in the energization current value when the energization current value is gradually increased can be determined based on the engine speed Ne. For example, the gradient of the change in the energization current value is such that the engine speed Ne when the idling stop condition is satisfied becomes large so that the rail pressure Pr does not fall below the injectable pressure Pr_inj until the internal combustion engine 40 is completely stopped. Accordingly, the inclination can be set to be small. By supplying a current as small as possible that satisfies such a condition, the rail pressure Pr increases significantly immediately after the execution of the automatic stop control of the internal combustion engine 40, and the durability of the common rail or the like may decrease. Is reduced.

  Further, the holding current value A_high may be configured to be set according to the fuel temperature Tq. When the fuel temperature Tq rises, the fuel density decreases and the fuel easily leaks to the low pressure side from the minute gaps existing in the fuel high pressure system, and the amount of fuel leakage in a predetermined time increases. Therefore, the rail pressure Pr may fall below the injectable pressure Pr_inj earlier than expected. Therefore, it is preferable to set the holding current value A_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.

  In the present embodiment, the predetermined time tw during which the current having the holding current value A_high is supplied is defined as a period from when the idling stop condition is satisfied until the engine speed Ne decreases to the predetermined threshold value Ne0. In the present embodiment, the threshold value Ne0 of the engine speed Ne is set to 0 rpm, and the predetermined time tw is about 1 to 2 seconds.

  Note that the predetermined time tw during which the current of the holding current value A_high is supplied can be defined as, for example, a period until the rail pressure Pr decreases to a predetermined pressure after the idling stop condition is satisfied, or an idling stop condition satisfaction signal is It can also be defined by the elapsed time from the time of receipt.

  By maintaining the rail pressure Pr at or above the injectable pressure Pr_inj at least until the engine speed Ne becomes zero, the internal combustion engine 40 is completely operated after the execution of the automatic stop control of the internal combustion engine 40 is started. When the restart condition is satisfied before the engine is stopped, the internal combustion engine 40 can be restarted quickly.

  Further, the pressure control valve control means 67 performs control to switch the energization current value to the pressure control valve 12 from the holding current value A_high to the minimum current value A_min after the elapse of the predetermined time tw. By controlling in this way, the battery consumption can be reduced after the internal combustion engine 40 is completely stopped. Although the minimum current value A_min is preferably zero from the viewpoint of reducing battery waste, the durability of the pressure control valve 12 due to repeated contact of the valve member with the seat surface when the internal combustion engine 40 is restarted. In order to prevent this, it is preferable to supply a small amount of current and keep the valve member in contact with the seat surface.

3. FIG. 3 is a time chart of FIG. 3 showing a conventional control method for an example of the control method executed by the control device 60 of the above-described accumulator fuel injector 50. A specific description will be given based on the time chart of FIG.

  3 and 4, when the restart condition of the internal combustion engine 40 is satisfied immediately after the execution of the automatic stop control of the internal combustion engine 40, the engine speed Ne, the rail pressure Pr, and the energization current to the pressure control valve 12 The change over time in each of the value and the open / close state of the pressure control valve 12 is indicated by a solid line. Further, in FIG. 4, each time change when the automatic stop state of the internal combustion engine 40 continues for a relatively long time is indicated by a broken line.

  In both FIG. 3 and FIG. 4, the current value to the pressure control valve 12 is feedback controlled according to the target rail pressure Ptgt until the time t1 when the idling stop condition is satisfied.

  In the conventional control method shown in FIG. 3, the current value supplied to the pressure control valve 12 is switched to the lowest current value A_min at the time t1 when the idling stop condition is satisfied. As a result, the pressure that can be maintained by the pressure control valve 12 rapidly decreases, so that at the time t2 immediately after t1, the rail pressure Pr can be injected even though the internal combustion engine 40 is not completely stopped. Below Pr_inj.

  Therefore, when the restart condition of the internal combustion engine 40 is satisfied at the time t3 before the time t4 when the internal combustion engine 40 is completely stopped, it is necessary to first increase the rail pressure Pr to the injectable pressure Pr_inj or higher. . However, during that time, the engine speed Ne decreases and the internal combustion engine 40 is temporarily stopped at the time t4. Therefore, the drive shaft of the internal combustion engine 40 is rotated again by a starter or the like to drive the high-pressure pump 5, The inside of the cylinder 41 needs to be compressed (period t4 to t5), and the resumption of fuel injection is delayed until the time t5.

  On the other hand, in the control method by the control device 60 of the present embodiment shown in FIG. 4, when the idling stop condition is satisfied at time t1, the energizing current value to the pressure control valve 12 is determined from the energizing current value A_base when the idling stop condition is met. It is gradually raised toward the holding current value A_high. Thereafter, until the internal combustion engine 40 is completely stopped, the fuel is pumped into the common rail 10 by the high-pressure pump 5, and immediately after the start of the automatic stop control of the internal combustion engine 40, the rail The rapid decrease in the pressure Pr is not observed.

  When the restart condition of the internal combustion engine 40 is satisfied at the time t12 before the time t13 when the internal combustion engine 40 is completely stopped, the rail pressure Pr is maintained at a value equal to or higher than the injectable pressure Pr_inj. In addition, fuel injection can be restarted promptly at a predetermined injection timing.

  Further, in the control method by the control device 60 of the present embodiment shown in FIG. 4, when the internal combustion engine 40 is completely stopped without satisfying the restart condition, the time t13 when the engine speed Ne becomes zero. Thus, the energization current value to the pressure control valve 12 is switched to the minimum current value A_min. If the internal combustion engine 40 is completely stopped, it will take time to restart the fuel injection anyway. Therefore, the amount of battery consumption can be reduced by reducing the energization amount to the pressure control valve 12. Reduction. Along with this, the holdable pressure by the pressure control valve 12 rapidly decreases, so that the rail pressure Pr decreases below the injectable pressure Pr_inj and enters a standby state until the restart condition is satisfied.

(2) Flowchart Next, an example of the control of the accumulator fuel injection device 50 executed by the control device 60 of the present embodiment will be specifically described based on the control flow of FIG.

  First, in step S11, it is determined whether or not an idling stop condition is satisfied. When the idling stop condition is satisfied, the process proceeds to step S12, the fuel injection by the fuel injection valve 13 is stopped, and the holding current value A_high is calculated in step S13. Thereafter, in step S14, the supply of the current having the holding current value A_high to the pressure control valve 12 is started.

  Thereafter, in step S15, it is determined whether or not a restart condition is satisfied. When the restart condition is satisfied, the internal combustion engine 40 is still in a state before being completely stopped, and the rail pressure Pr is also maintained at the injectable pressure Pr_inj or higher. Resume injection.

  On the other hand, if the restart condition is not satisfied, the process proceeds to step S17, and it is determined whether or not the engine speed Ne is equal to or less than a threshold value Ne0. In the example of the present embodiment, it is determined whether or not the engine speed Ne has become zero. When the engine speed Ne is equal to or less than the threshold value Ne0, the process proceeds to step S18. When the engine speed Ne exceeds the threshold value Ne0, the process returns to step S15. Until the engine speed Ne becomes equal to or less than the threshold value Ne0, the determination of whether or not the restart condition is satisfied is repeated while supplying the current of the holding current value A_high to the pressure control valve 12.

  In step S18 that has proceeded when the engine speed Ne is equal to or less than the threshold value Ne0, the energization current value to the pressure control valve 12 is switched from the holding current value A_high to the minimum current value A_min. By switching the supply current, the rail pressure Pr drops below the injectable pressure Pr_inj. Thereafter, the determination of whether or not the restart condition is satisfied is repeated until the restart condition is satisfied in step S19.

  When the restart condition is satisfied in step S19, the process proceeds to step S20, and after starting the control of the energization current value to the pressure control valve 12, the starter is operated in step S21 to rotate the drive shaft of the internal combustion engine 40, and the high pressure pump The fuel is supplied from 5 to the common rail 10. As a result, the rail pressure Pr gradually increases.

  In step S22, it is determined whether or not the rail pressure Pr is equal to or higher than the injectable pressure Pr_inj. When the rail pressure Pr is equal to or higher than the injectable pressure Pr_inj, the process proceeds to step S16 to restart fuel injection.

  By executing automatic stop control of the internal combustion engine 40 based on the establishment of the idling stop condition according to the control flow described above, the internal combustion engine 40 is being automatically stopped in a system that basically cannot maintain the rail pressure Pr above the injectable pressure Pr_inj. However, only when the restart condition is satisfied after the start of the automatic stop control of the internal combustion engine 40 until the internal combustion engine 40 completely stops. The fuel injection can be restarted quickly and the internal combustion engine 40 can be restarted.

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 rate control valve control means, 67: pressure control valve control means, 68: fuel injection valve control means,

Claims (6)

Connected to the common rail, a common rail that accumulates fuel pumped by a high-pressure pump, a normally open structure that opens the fuel flow path in a non-energized state, and that regulates the pressure in the common rail A fuel injection valve that injects the fuel into a cylinder of the internal combustion engine, and the fuel injection valve releases a back pressure applied to a back end side of a nozzle needle that opens and closes the injection hole. In addition to the passage, a control device for an accumulator fuel injection device having a leak passage for returning a part of the fuel sent to the fuel injection valve to a low pressure side, and capable of executing idling stop control of the internal combustion engine In the control device of the fuel injection device,
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 when the idling stop condition is satisfied, and restarting fuel injection by the fuel injection valve when the restart condition is satisfied;
Until the predetermined time elapses after the idling stop condition is satisfied, the energization current value to the pressure control valve is maintained at or higher than the energization current value when the idling stop condition is satisfied, and after the predetermined time has elapsed, A pressure control valve control means for reducing an energization current value to the pressure control valve to be less than an energization current value when the idling stop condition is established;
Equipped with a,
Wherein in a case where the raising the electric current value to the pressure control valve in a predetermined time, the pressure control valve control means control device for accumulator fuel injection device according to claim Rukoto gradually increasing the energization current value. In case of gradually increasing the energization current value, the pressure control valve control means, wherein the inclination of the change of the energizing current to claim 1, wherein the determining in accordance with the rotational speed of the internal combustion engine Control device for accumulator fuel injection system. 3. The control device for an accumulator fuel injection device according to claim 1, wherein the pressure control valve control means determines an energization current value to the pressure control valve at the predetermined time according to a fuel temperature. 4. . The pressure accumulation according to any one of claims 1 to 3 , wherein the predetermined time is a time from when the fuel injection is stopped until the rotational speed of the internal combustion engine decreases to a predetermined threshold value. Type fuel injection device control device. Connected to the common rail, a common rail that accumulates fuel pumped by a high-pressure pump, a normally open structure that opens the fuel flow path in a non-energized state, and that regulates the pressure in the common rail A fuel injection valve that injects the fuel into a cylinder of the internal combustion engine, and the fuel injection valve releases a back pressure applied to a back end side of a nozzle needle that opens and closes the injection hole. A method for controlling an accumulator fuel injection apparatus having a leak passage for returning a part of the fuel sent to the fuel injection valve to a low pressure side in addition to the passage, and capable of executing idling stop control of the internal combustion engine In the control method of the fuel injection device,
Until a predetermined time elapses after the predetermined idling stop condition is satisfied, the energization current value to the pressure control valve is maintained to be equal to or higher than the energization current value when the idling stop condition is satisfied, and after the predetermined time has elapsed. , Reducing the energization current value to the pressure control valve to less than the energization current value when the idling stop condition is satisfied ,
In the case of increasing the electric current value to the pressure control valve in the predetermined time, the control method of the accumulator fuel injection apparatus according to claim Rukoto gradually increasing the energization current value. Connected to the common rail, a common rail that accumulates fuel pumped by a high-pressure pump, a normally open structure that opens the fuel flow path in a non-energized state, and that regulates the pressure in the common rail A fuel injection valve that injects the fuel into a cylinder of the internal combustion engine, and the fuel injection valve releases a back pressure applied to a back end side of a nozzle needle that opens and closes the injection hole. A pressure accumulation type fuel injection device having a leak passage for returning a part of the fuel sent to the fuel injection valve to the low pressure side in addition to the passage, and comprising a control device capable of executing an idling stop control of the internal combustion engine In the accumulator type fuel injection device,
The control device includes:
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 when the idling stop condition is satisfied, and restarting fuel injection by the fuel injection valve when the restart condition is satisfied;
Until the predetermined time elapses after the idling stop condition is satisfied, the energization current value to the pressure control valve is maintained at or higher than the energization current value when the idling stop condition is satisfied, and after the predetermined time has elapsed, A pressure control valve control means for reducing an energization current value to the pressure control valve to be less than an energization current value when the idling stop condition is established;
Equipped with a,
Wherein in a case where the raising the electric current value to the pressure control valve in a predetermined time, the pressure control valve control means accumulator fuel injection device according to claim Rukoto gradually increasing the energization current value.

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