JP2000282998A - Accumulator fuel injection device and control method for internal pressure of accumulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accumulator fuel injection device for a diesel engine capable of exerting a pressure sinking performance sufficiently, while an increase of the thermal load given to an injector driving circuit is suppressed, when the internal pressure of a common rail of the injection device is subjected to a decompression control. SOLUTION: When the decompression conditions for lowering the fuel pressure in a common rail 3 are established, a solenoid valve 1a of an injector 1 is subjected to an idle strike, so that the valve opening is made in a time width shorter than a delay time tm at which a nozzle needle 37 will open, and thereby the internal pressure of the common rail is reduced, wherein the temp. of an injector drive circuit in an ECU 7 is predicted on the basis of the cooling water temp. sensed by a sensor 71, and on the basis of the obtained temp., the cyclic period of the idle stroke drive is decided, so that the thermal load given to the injector drive circuit does not exceed the limitation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator (common rail) for storing high-pressure fuel pumped from a fuel supply pump.
The present invention relates to a pressure accumulating type fuel injection device having a pressure accumulating chamber for injecting high-pressure fuel in the accumulating chamber to a cylinder of a diesel engine, and a method for controlling the pressure in the accumulating chamber.

[0002]

2. Description of the Related Art In order to supply fuel to a diesel engine mounted on a vehicle, an accumulator type fuel injection device having an accumulator, a so-called common rail, is used. In such a pressure accumulating type fuel injection device, a control target value of a fuel pressure in a common rail (common rail pressure), a fuel injection amount, and a fuel injection timing is calculated based on an operation state (a rotation speed, a load, and the like) of the diesel engine. At the same time, the fuel discharge amount from the fuel supply pump is feedback-controlled so that the common rail pressure becomes the target common rail pressure, and at the same time, the high-pressure fuel in the common rail is injected and supplied to the cylinder of the diesel engine with the calculated fuel injection amount and fuel injection timing. The driving of the injector is controlled in such a manner.

[0003] An injector used in this type of device usually has a valve body that opens by the pressure of fuel supplied from a common rail through a first flow path and injects fuel into a cylinder of a diesel engine. A driving unit for closing the valve body by the pressure of the fuel supplied from the common rail through the second flow path, and a fuel supplied from the common rail to the driving unit by being driven to open. Equipped with an electromagnetic valve for allowing the fuel to overflow to the low pressure side of the fuel system. The valve element opens when the solenoid valve opens and fuel supplied to the drive unit overflows to the low pressure side, and when the solenoid valve closes, fuel supplied to the drive unit is opened. Is closed by the pressure of.

However, in the conventional pressure-accumulation type fuel injection system, for example, when the diesel engine is suddenly decelerated and then re-enters an acceleration state, or when the engine is restarted immediately after stopping, the common rail is used. In some cases, the pressure became higher than the target common rail pressure, and fuel at an unnecessarily high pressure was supplied. For example, when the diesel engine is rapidly decelerated, when the driver stops depressing the accelerator pedal, the calculated fuel injection amount becomes zero and the fuel injection is stopped. Thereafter, when the accelerator pedal is depressed again, the fuel injection amount and the fuel injection timing are set according to the operating state at that time, and fuel injection is restarted.
At this time, the common rail pressure is maintained near the target pressure before deceleration and is not reduced. For this reason, the common rail pressure at the time of resuming becomes higher than the target common rail pressure, and there is a possibility that fuel is injected at once at the same time as the valve body of the injector opens.

[0005] A similar problem may occur when the diesel engine is stopped immediately after it is operated at a high load and restarted immediately, or when a starter switch for starting the engine is repeatedly turned on / off. . Such a state is continued until the common rail pressure decreases to the target common rail pressure, and during that time, an unnecessarily high pressure fuel is supplied from the injector, thus causing a problem such as noise.

Therefore, the solenoid valve for controlling the opening and closing of the injector is driven to open in a time width shorter than the time required for the valve element for fuel injection to open, so that the high-pressure fuel in the common rail is supplied to the fuel system. An apparatus has been proposed in which the common rail pressure is reduced by overflowing to the low pressure side of the apparatus. That is, in the injector having the above-described configuration, there is a predetermined delay time (a so-called invalid injection time) from when the solenoid valve is opened to when the valve body of the injection unit is actually opened. By performing the idle driving to open the solenoid valve for a certain time, it is possible to overflow the high-pressure fuel supplied to the drive unit and reduce the common rail pressure.

[0007]

In the above-mentioned conventional apparatus, the control of the common rail pressure by the idling drive is specifically performed under a predetermined pressure reduction condition, for example, when the calculated fuel injection amount is zero and the common rail pressure is reduced. When the condition that the pressure is higher than the target common rail pressure is satisfied, the timing is synchronized with the rotation of the diesel engine (specifically, the rotation of the crankshaft). However, when the rotation speed of the diesel engine is low and the rotation speed of the diesel engine is low, the number of times of idle driving per unit time is reduced by synchronizing with the rotation of the diesel engine. It is more effective to repeat the idle driving. The method of performing idle driving at regular intervals is effective even when the diesel engine is stopped, and the advantage that the minimum required number of idle driving per unit time can be performed regardless of the rotational state of the diesel engine. There is.

However, when the cycle of the idle driving is previously set as in the above method, the thermal load applied to the drive circuit of the injector is not excessively increased even under the operating condition in which the drive circuit of the injector becomes hot. In addition, it is necessary to set the cycle of the idle driving. In other words, in order to set the cycle of idle driving based on the high temperature when the heat load applied to the drive circuit becomes large, at the time of low temperature when the heat load has a margin, it is set from the thermal limit of the drive circuit. The difference between the possible period and the actual period became large, and there was a disadvantage that the step-down performance could not be sufficiently obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the common rail pressure at low temperatures quickly while suppressing an increase in the thermal load applied to the injector drive circuit. It is an object of the present invention to provide a pressure accumulating fuel injection device capable of maximizing performance and a method of controlling a pressure in a pressure accumulating chamber.

[0010]

According to a first aspect of the present invention, there is provided a pressure-accumulation type fuel injection device which stores a high-pressure fuel pumped from a fuel supply pump, and an injector for injecting the high-pressure fuel in the pressure accumulator into a cylinder of a diesel engine. Controlling the driving of the fuel supply pump and the injector in accordance with the operating state of the diesel engine to thereby inject fuel to the diesel engine; and controlling the temperature of the control unit directly or indirectly. And temperature detecting means for detecting the temperature. An injector having a valve body that opens with a pressure of fuel supplied from the pressure accumulating chamber via a first flow path and injects the fuel into a cylinder of a diesel engine;
A driving unit that closes the valve body by the pressure of the fuel supplied from the accumulator through the second flow path; and a fuel that is supplied to the driver from the accumulator by driving the valve to open. An electromagnetic valve that overflows to the low pressure side of the fuel system is provided, and the valve body is configured to open in accordance with the opening of the electromagnetic valve, and the control unit controls an operation state of the diesel engine. Condition determination means for determining whether or not a pressure reducing condition for reducing the fuel pressure in the pressure accumulating chamber is satisfied, and a time shorter than a delay time until the valve element opens the solenoid valve. A valve opening drive with a width, a pressure reducing means for performing an idling drive to overflow the high pressure fuel in the pressure accumulating chamber to the low pressure side, and when it is determined that the pressure reducing condition is satisfied by the condition satisfaction determining means. The control unit detected by the temperature detection unit Based on the temperature, the cycle of the idle driving by the pressure reducing means is determined so that the heat load received by the control unit does not exceed the limit, and the pressure reducing means is operated in the cycle to reduce the fuel pressure in the accumulator. The apparatus is provided with a decompression executing means for decreasing the pressure.

According to the above arrangement, the temperature of the control unit for controlling the driving of the injector is detected by the temperature detecting means, and based on the detected temperature, the temperature is controlled within a range not exceeding the heat load limit of the control unit. The period of the idle driving is determined. That is, since the optimal cycle can be set below the thermal limit, when the temperature is low at which the thermal load has a margin, the pressure reducing means is operated in a cycle shorter than that at the time of the high temperature to quickly reduce the fuel pressure in the accumulator. be able to. In this way, by setting the cycle of the idle driving inconstantly and changing the setting appropriately in accordance with the temperature of the control unit, it is possible to suppress the increase in the thermal load and maximize the step-down performance thereof. it can.
Then, as a result of effective control of the pressure in the accumulator, inconveniences such as noise can be effectively prevented.

According to a second aspect of the present invention, the control section drives the solenoid valve in synchronization with the rotation of the diesel engine to inject fuel to a cylinder of the diesel engine to supply fuel to the cylinder. When the fuel pressure in the pressure accumulating chamber is reduced by the driving for driving, and the condition satisfaction determining means determines that the pressure reducing condition is not satisfied, the fuel injection is stopped immediately after the fuel injection by the fuel injection means. Means are provided.

When the pressure reducing means is operated to perform idle driving, and the fuel pressure in the accumulator falls below the target pressure,
The determination by the condition satisfaction determination means switches to a determination that the pressure reduction condition is not satisfied. At this time, if the interval between the timing of the last idle driving and the timing of the next fuel injection is too short, a large amount of fuel may be unexpectedly injected at the time of fuel injection by the fuel injection means. In the above configuration, in order to prevent this, the fuel injection suspending means is provided, and by stopping the fuel injection immediately after performing the idling driving, the fuel exceeding the target value is prevented from being injected. be able to.

According to a third aspect of the present invention, the temperature detecting means indirectly detects the temperature of the control unit from at least one of the cooling water temperature and the intake air temperature of the diesel engine. The temperature of the control unit can be predicted based on the cooling water temperature or the intake air temperature of the diesel engine, and by using an existing temperature sensor or the like, the temperature of the control unit can be reduced without increasing the number of parts. Can be detected.

According to the fourth aspect of the present invention, the pressure reduction executing means determines the valve opening drive time of the solenoid valve during the idle driving according to the fuel pressure of the pressure accumulation chamber. It has been found that the settable maximum time of the valve opening driving time (idling driving time) of the solenoid valve at the time of the idling driving varies according to the fuel pressure of the accumulator. Therefore, if the setting of the idle driving time is changed as needed based on the fuel pressure, for example, when the risk of erroneous injection into the cylinder is small, the idle driving time can be lengthened. The step-down performance can be improved by opening the solenoid valve.

According to a fifth aspect of the present invention, the diesel engine has a plurality of the cylinders, a plurality of the injectors are provided corresponding to each of the cylinders, and the decompression means operates the solenoid valves of the injectors in order or two. The above operations are simultaneously performed to open the valve. When the diesel engine is a multi-cylinder engine, the plurality of corresponding injectors are sequentially driven by idle driving, so that the thermal load received by the drive circuit of the injector can be dispersed. Alternatively, if two or more injectors are simultaneously driven to open the valve, the pressure reduction time can be shortened.
The step-down performance can be improved.

According to a sixth aspect of the present invention, there is provided a pressure accumulating chamber pressure control method for storing a high pressure fuel pumped from a fuel supply pump, an injector for injecting the high pressure fuel in the pressure accumulating chamber into a cylinder of a diesel engine, and the diesel engine. A control unit that injects fuel to the diesel engine by controlling the driving of the fuel supply pump and the injector according to the operating state of the diesel engine, and a temperature detection unit that directly or indirectly detects the temperature of the control unit. Means, wherein the injector has a valve body that opens a valve by the pressure of fuel supplied from the accumulator through the first flow path and injects the fuel into a cylinder of a diesel engine. A drive unit for closing the valve body by the pressure of the fuel supplied from the accumulator through the second flow path, and a drive unit for opening the valve from the accumulator by driving the valve to open. An accumulator-type fuel injection device, comprising: an electromagnetic valve that causes supplied fuel to overflow to a low-pressure side of the fuel system, wherein the valve element is configured to open with the opening of the electromagnetic valve. When the pressure reducing condition for lowering the fuel pressure in the accumulator is satisfied, the solenoid valve is driven to open with a time width shorter than the delay time required for the valve body to open. The pressure in the accumulator is controlled by overflowing the high-pressure fuel in the accumulator to the low-pressure side. Then, the temperature of the control unit is directly or indirectly detected, and based on the detected temperature, the cycle of the idle driving of the solenoid valve is determined so that the heat load received by the control unit does not exceed a limit. I do.

According to the above method, the cycle of the idle driving is not fixed, and the setting can be appropriately changed according to the temperature of the control unit within a range where the heat load does not exceed the limit. And the step-down performance can be maximized.

According to a seventh aspect of the present invention, in the method of the fourth aspect, the fuel injection by the injector is stopped immediately after the fuel pressure in the pressure accumulating chamber is reduced and the idling drive of the solenoid valve is stopped. Thus, it is possible to prevent an unexpectedly large amount of fuel from being injected immediately after the idle driving.

In the method according to the eighth aspect, the temperature of the control unit is indirectly detected from at least one of a cooling water temperature and an intake air temperature of the diesel engine. By calculating the temperature of the control unit based on the cooling water temperature or the intake air temperature at which an existing temperature sensor or the like can be used, the above effects of the present invention can be easily obtained.

According to a ninth aspect of the present invention, a plurality of the injectors are provided corresponding to each of the plurality of cylinders of the diesel engine, and the solenoid valves of the injectors are sequentially opened or two or more are simultaneously opened. .
By sequentially driving a plurality of injectors by idle driving, the effect of dispersing the thermal load received by the drive circuit can be obtained, and if two or more injectors are simultaneously driven to open,
The step-down time can be shortened, and the step-down performance can be improved while suppressing an increase in heat load.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a pressure accumulating fuel injection device according to the present embodiment, and is a four-cylinder diesel engine (hereinafter, referred to as an engine) mounted on a vehicle.
The figure is applied to The accumulator type fuel injection device includes four injectors (fuel injection valves) 1 for injecting fuel into each cylinder of the engine, a common rail 3 as a pressure accumulating chamber for accumulating fuel supplied to each injector 1, and a common rail 3. A high-pressure pump 5 as a fuel supply pump for pumping high-pressure fuel, and an electronic control unit (hereinafter referred to as an ECU) as a control unit for controlling these according to the operating state of the engine.
7).

FIG. 1 specifically shows only the injector 1 for one cylinder and its piping system and control system among the injectors 1 of each cylinder, but the other three injectors 1 have the same configuration. It has become. The high-pressure pump 5 has a well-known structure in which the discharge amount of the fuel is variable. The high-pressure pump 5 sucks the fuel stored in the fuel tank 9 through the low-pressure pump 11 in accordance with a control command from the ECU 7, and It is pressurized to a high pressure in the provided pressurizing chamber. And
The high-pressure fuel is fed to the common rail 3 via the supply pipe 13 under pressure.

Each injector 1 has an injection section provided with a nozzle needle 37 serving as a valve body for injecting fuel by opening the lower half by the pressure of the supplied fuel and the upper half thereof by the pressure of the supplied fuel. To drive the nozzle needle 37. The injector 1 is connected to the common rail 3 by a pipe 15, and high-pressure fuel supplied through the pipe 15 branches in the injector 1, and a control chamber 43 of a drive unit and an oil sump chamber of an injection unit described later. 47 are supplied through first and second flow paths, respectively. Further, the drive unit of the injector 1 is connected to a flow path 51 communicating with the fuel tank 9 on the low pressure side of the fuel system, and an electromagnetic valve 1a described later is provided in the middle of the flow path 51. .

Here, the driving section of the injector 1 comprises a cylindrical holder body 21 which forms a core thereof, two disk-shaped orifice plates 23 and 25 which are sequentially attached to the upper end of the holder body 21, and a holder. A piston 27 slidably disposed in the hollow portion of the body 21 in the up-down direction, extends downward from the lower end of the piston 27 in the hollow portion of the holder body 21, and has a flange 29 at the tip (lower end in the figure).
And a piston pin 31 attached thereto.

At the lower part of the holder body 21, a substantially cylindrical nozzle body 35 having a closed lower end and serving as a core of the injection portion of the injector 1 is mounted via a tip packing 33, and a valve body is provided in the hollow part of the nozzle body 35. The above nozzle needle 37 is disposed. Nozzle needle 37
The large diameter portion 37a in the upper half is slidably arranged in the hollow portion of the nozzle body 35 in the vertical direction.
7a through the tip packing 33 and the holder body 2
The connecting portion 37b extends to the inside of the first portion. Connecting part 37b
Is connected to the flange 29 at the lower end of the piston pin 31 so that the piston 27 and the nozzle needle 3
7 can be moved up and down integrally. A spring 39 is provided between the flange 29 and the inner wall of the holder body 21 above the flange 29 to apply a biasing force to the nozzle needle 37 in the valve closing direction (downward in the figure).

In the holder body 21, a flow path 41 communicating with the pipe 15 connected to the common rail 3 is provided.
Are formed, and the flow path 41 is branched in the vertical direction on the way. One of the flow passages extending downward constitutes a first flow passage together with a flow passage 45 that penetrates the chip packing 33 and reaches the inside of the nozzle body 35.
Is connected to the oil sump chamber 47 formed around the nozzle needle 37 below the large diameter portion 37a.

The tip of the nozzle body 35 (the lower end in the figure)
Are formed with a plurality of fuel injection holes 49 communicating with the oil sump chamber 47. Then, the control room 43
The conical tip of the nozzle needle 37 (the lower end in the figure) due to the fuel pressure inside and the urging force of the spring 39
Is a conical valve seat 35a formed on the nozzle body 35.
, The space between the oil sump chamber 47 and the injection hole 49 is shut off, and the injector 1 is closed (the state shown in the figure).
Becomes

The other of the flow passages 41, which extends upward, constitutes a second flow passage together with the orifice 23a and the flow passage 23b formed in the orifice plate 23. , And communicates with the control chamber 43 provided on the back side (upper side in the figure) of the piston 27 in the holder body 21.

The control chamber 43 includes the orifice plate 2
The orifice 25 is connected to the flow path 51 which communicates with the fuel tank 9 via an orifice 25 a formed in the fuel tank 9. The solenoid valve 1a whose opening and closing is controlled by the ECU 7 is provided in the middle of the flow path 51. When the solenoid valve 1a is opened, the control chamber 4a is opened.
The high-pressure fuel in the tank 3 overflows to the fuel tank 9 through the orifice 25a and the flow path 51. In addition,
The solenoid valve 1a is configured to be opened by energizing its exciting coil (not shown) by the ECU 7, and to be closed when not energized.

The oil sump chamber 47 passes through a gap between the upper large diameter portion 37a and the nozzle body 35, and the control chamber 43 passes through a gap between the lower piston 27 and the holder body 21.
The spring 39 communicates with a space 81 in the holder body 21 in which the spring 39 is housed. This space 81 is the holder body 2
1 and an orifice plate 23, 25, which communicates with a flow path 83.
a is connected to the flow path 51 downstream. This allows
Excess high-pressure fuel leaking from the oil sump chamber 47 and the control chamber 43 into the space 81 overflows into the fuel tank 9 via the flow paths 83, 53, and 51.

In the injector 1 configured as described above, the high-pressure fuel supplied from the common rail 3 through the pipe 15 branches in two directions (up and down directions) in the flow path 41 in the holder body 21. The one extending downward passes through the chip packing 33 and the flow path 45 formed in the nozzle body 35 as a first flow path,
5 flows into the oil sump chamber 47. On the other hand, as the second flow path, the orifice plate 23 of the orifice plate 23 is used.
a and flows into the control chamber 43 on the back side of the piston 27 via the flow path 23b.

That is, the nozzle needle 37 is connected to the control chamber 4
In addition to receiving the force in the direction of pushing down (valve closing direction) due to the fuel pressure in the fuel tank 3, the fuel pressure in the oil reservoir chamber 47 receives the force in the direction of pushing up (valve opening direction). Here, the area of the large-diameter portion 37a of the nozzle needle 37 receiving the fuel pressure in the oil sump chamber 47 (the oil sump chamber 47).
The area of the back surface of the piston 27 that receives the fuel pressure in the control chamber 43 is larger than the area of the outer peripheral part of the lower surface of the large diameter part 37a facing the When the solenoid valve 1a is closed, the downward force in FIG. 1 is superior as a whole. Therefore, when the solenoid valve 1a is closed, the lower end of the nozzle needle 37 is pressed against the valve seat 35a of the nozzle body 35 to close the valve, and the fuel is not injected into the cylinder of the engine.

On the other hand, when the exciting coil of the solenoid valve 1a is energized by the ECU 7 and the solenoid valve 1a is opened, the high-pressure fuel flowing into the control chamber 43 from the common rail 3 is transferred to the orifice 25a of the orifice plate 25 by the electromagnetic force. Valve 1
a, and overflows into the low-pressure fuel tank 9 through the flow path 51. As a result, the nozzle needle 37 rises due to the fuel pressure in the oil sump chamber 47, the lower end thereof separates from the valve seat 35a, and the valve is opened, and fuel is injected from the injection hole 49 to the corresponding engine cylinder.

Thereafter, when the ECU 7 stops supplying power to the exciting coil of the solenoid valve 1a and closes the solenoid valve 1a, the fuel pressure in the control chamber 43 increases again. Accordingly, the nozzle needle 37 moves in the valve closing direction, and the valve seat 35 moves.
a, the injector 1 returns to the valve closed state.

FIG. 2 shows this state. When the solenoid valve 1a is opened, the fuel pressure (control chamber pressure) in the control chamber 43 starts to decrease, but at this time, the nozzle needle 37 in FIG.
The lift amount (movement amount in the valve opening direction) does not change. Thereafter, the control chamber pressure gradually decreases, and the sum of the force in the downward direction (valve closing direction) due to the control chamber pressure and the urging force by the spring 39 becomes the upward direction (valve opening direction) due to the fuel pressure in the oil reservoir chamber 47. When the force falls below this force, the nozzle needle 37 starts to move in the valve opening direction.

At this time, the injector 1 of the present embodiment
The movement of fuel from the control chamber 43 to the fuel tank 9 may be limited by the orifice 25a of the orifice plate 25, and the opening direction of the solenoid valve 1a to the valve opening direction of the nozzle needle 37 as shown in FIG. A predetermined delay time tm (for example, about 0.4 ms)
(Milliseconds)). Therefore, if the solenoid valve 1a is opened for a time width shorter than the delay time tm, the high-pressure fuel from the common rail 3 overflows through the control chamber 43 without injecting the fuel, and the pressure of the common rail 3 decreases. (Hereinafter referred to as idle driving). Details of this control by the ECU 7 will be described later.

As shown in FIG. 1, the ECU 7 serving as a control unit executes a program for controlling the engine.
The main components are a well-known microcomputer including a PU 61, a ROM 63 for storing a program to be executed by the CPU 61, and a RAM 65 for temporarily storing the calculation results of the CPU 61.

The ECU 7 includes a crankshaft 3 of the engine.
A crank angle sensor 67 that outputs a pulse-like crank angle signal every time it rotates 0 ° (every 30 ° CA), an accelerator sensor 69 for detecting an accelerator opening Ac that represents the load of the engine, and a temperature of the control unit indirectly Temperature sensor 71 for detecting the engine coolant temperature THW, which constitutes a temperature detecting means for detecting the temperature, the engine crankshaft is 2
A cylinder discrimination sensor 73 that outputs a pulse-shaped cylinder discrimination signal KS every time the crankshaft reaches a specific rotation angle position each time the crankshaft rotates, and detects an actual fuel pressure (actual common rail pressure) PC in the common rail 3. Signal from various sensors such as a common rail pressure sensor 75
An input circuit 77 for inputting to the PU 61 and an input circuit 79 for driving the solenoid valve 1 a and the high-pressure pump 5 from each injector 1 according to a command from the CPU 61 are provided.

Based on signals from the sensors 67 to 75, the ECU 7 operates the engine such as the engine speed (engine speed) Ne, accelerator opening Ac, cooling water temperature THW, and actual common rail pressure PC. Detect state. Then, a target fuel pressure (target common rail pressure) PF in the common rail 3 for realizing a fuel injection pressure such that the combustion state of the engine becomes an optimum combustion state according to the detected operating state is calculated, Feedback control of the common rail pressure is performed to drive and control the high-pressure pump 5 so that the actual common rail pressure PC detected by the common rail pressure sensor 75 matches the target common rail pressure PF.

The ECU 7 calculates the target fuel injection amount and the injection timing based on the detected operating state, and synchronizes with the rotation of the engine based on signals from the crank angle sensor 67 and the cylinder discriminating sensor 73. The fuel injection to the engine is controlled by opening and closing the solenoid valve 1a of each injector 1 at the timing.

Further, when the ECU 7 determines that the pressure reducing condition for reducing the common rail pressure is satisfied based on the detected operating state, the ECU 7 sets the solenoid valve 1a of the injector 1 to the above-described delay time (for the injector 1). High-pressure fuel flowing from the common rail 3 into the control chamber 43 of the injector 1 by performing idle driving in which the valve is driven to open with a time width shorter than the time tm until the nozzle needle 37 of the solenoid valve 1a opens) Overflows into the fuel tank 9 to reduce the common rail pressure. A feature of the present invention is that the setting of the cycle when performing the idling drive is performed by, for example, the cooling water temperature TH
This is based on the temperature of the ECU 7 which is indirectly known from W, more specifically, the temperature of the injector drive circuit (corresponding to the output circuit 79 in FIG. 1) which is likely to become high in temperature. And EC
The common rail pressure can be effectively reduced by changing the cycle of the idle driving as needed in accordance with a change in the U7 temperature, within a range in which the thermal load applied to the injector drive circuit does not exceed the limit.

Therefore, in the present embodiment, the processing executed by the ECU 7 to control the fuel injection into the engine and the pressure of the common rail 3 will be described with reference to the flowcharts shown in FIGS. It is explained along. In addition, the ECU 7 periodically executes a detection process (not shown) separately from the processes of FIGS. 3 to 6.
And the like, the latest engine speed Ne, accelerator opening Ac, cooling water temperature THW, actual common rail pressure PC, and the like are detected. For example, the engine speed Ne is detected by measuring a time interval during which the crank angle signal CS is output from the crank angle sensor 67,
The accelerator opening Ac, the coolant temperature THW, and the actual common rail pressure PC are detected by A / D converting analog signals from the accelerator sensor 69, the water temperature sensor 71, and the common rail pressure sensor 75, respectively. This detection processing and the processing of FIGS.
A program that is executed by the U61 and that causes the CPU 61 to perform each of these processes is stored in the ROM 63 in advance.

FIG. 3 is a flowchart showing the common rail pressure control processing, which is usually executed at predetermined time intervals or as an interrupt routine synchronized with the rotation of the engine. As shown in FIG. 3, when the execution of the common rail pressure control process is started, first in S100 (step 100), the engine speed Ne and the injection amount command value Q representing the target fuel injection amount are set.
And the actual common rail pressure PC, and then S10
1 and the engine speed Ne and the injection amount command value Q
Based on this, the target common rail pressure PF is calculated. Note that the injection amount command value Q is calculated in S202 of FIG. In general, the target common rail pressure PF increases as the engine speed Ne or the injection amount command value Q increases.
It is calculated as a large value. Then, in S102, the high-pressure pump 5 is driven so that the actual common rail pressure PC matches the target common rail pressure PF,
The fuel is pressure-fed, and this processing is once ended.

FIG. 4 is a flow chart showing the injector control process. In the case of a four-cylinder engine, it is performed as an angle synchronization routine executed every time the crankshaft of the engine rotates 180 degrees (every 180 ° CA). In the present embodiment, as shown in FIG.
This processing is executed with the output of the crank angle signal CS representing ° CA as a signal (for example, at time t1,
t2, t3, t4, t5). FIG. 10 shows an injection amount command value Q calculated based on the present process, an idling flag FK indicating whether or not to perform idling driving, an energization signal to the solenoid valve 1a for controlling the injector 1, The common rail pressure PC and the target common rail pressure PF are shown together.

In FIG. 4, when the execution of the injector control process is started, first in S201, the engine speed N
e and the accelerator opening Ac are read, and an injection amount command value Q is calculated based on the engine speed Ne and the accelerator opening Ac read in S202. In general, the injection amount command value Q is calculated as a larger value as the accelerator opening Ac is larger. Next, in S203, the blank hit flag F that stores the value of the blank hit flag FK at that time.
KOLD is set to 0 or 1, and it is determined whether or not the injection amount command value Q calculated in S204 is 0 or less.
Proceed to 205.

In S205, the blank hit flag FKOLD is set to
It is determined whether or not it is 1 indicating that the idle driving is performed, and
If the idling flag FKOLD is 1, the idling flag FK is set to 0 indicating that idling driving is not performed in S206, and the injector control process ends. S20
If the blank hit flag FKOLD is not 1 at 5, S 20
The routine proceeds to step 7, where a normal fuel injection control process is executed, and the injector control process ends.

Here, the fuel injection control processing of S207 will be described. For example, in the injector control process executed at time t1 in FIG.
> 0, and in S205, the blank hit flag FKOLD = 0, so that a negative determination is made in any case, and the process proceeds to S207.
Here, first, a time TQ (> t) for opening the solenoid valve 1a of the injector 1 based on the engine speed Ne, the injection amount command value Q, the actual common rail pressure PC, and the like.
m, corresponding to the fuel injection amount) and its valve opening start timing TT (corresponding to the fuel injection timing). Then, when the calculated solenoid valve opening timing TT arrives (at time t1 in FIG. 10).
1) When the exciting coil of the solenoid valve 1a is energized and opened for the calculated solenoid valve opening time TQ, fuel is injected from the injection hole 49 of the injector 1 during that time.

The processing in S205 and S206 is the same as that in FIG.
As shown at time t41 of 0, the normal fuel injection control process is suspended only once immediately after performing the idling drive process. For example, actual common rail pressure PC
When the time until the next fuel injection timing (corresponding to the time between the times t4 and t41 in FIG. 10) after the idle driving is completed after reaching the target common rail pressure PF is very short,
There is a possibility that a large amount of fuel may be unexpectedly injected into the cylinder of the engine together with the valve opening of the injector 1 without sufficiently reducing the pressure of the fuel storage chamber 47 of the injector 1. This can be prevented by always stopping the fuel injection immediately after the driving process.

If it is determined in step S204 that the injection amount command value Q is equal to or smaller than 0, the process proceeds to step S208 to execute the idling driving process. In S208, as another condition for performing the idle driving, the actual common rail pressure P
C and target common rail pressure PF (PC-P
F) is a predetermined pressure H (for example, 2 MPa (megapascal))
It is determined whether it is greater than or equal to. And PC-PF>
When it is determined to be H, the high-pressure pump 5 is stopped in S209, 1 is set in the idling flag FK in S210, and this processing ends. If it is determined that PC-PF> H is not established, the idling flag FK is set to 0 in S211 and the injector control process is terminated as it is.

The process shown in FIG. 4 is for determining whether or not to execute the idle driving.
This is performed based on the idling control process shown in the flowchart shown in FIG. FIG. 5 shows that in the case of a four-cylinder engine, every time the crankshaft of the engine rotates 180 degrees (180 ° CA
In this embodiment, as shown in FIG. 10, crank angle = 150 °
The crank angle signal of CA is signaled (for example, FIG.
0 time t21, t31). First, in S301, S in FIG.
At 203, it is determined whether or not the idle hit flag FKOLD is 1, and if FKOLD = 1, the process is terminated. If FKOLD is not 1 in S301, the process proceeds to S302.

Here, the process of S301 is for determining whether or not the idle driving control process is ongoing.
Since the temperature condition does not greatly change during one depressurization process, in the present embodiment, from the start of the idling control process to the end of the depressurization, it is assumed that the idling drive is performed in the same cycle, S3 in FIG. 5 for setting the blanking condition
02 and subsequent processes are not executed. For example, in the idling control process executed at time t31 in FIG. 10, the idling control process executed at time t21 is continued.
Since FKOLD = 1 at 01, the idling drive according to this process is not performed.

In S302, it is determined whether or not the idle driving flag FK is 1 in order to confirm whether or not the conditions for performing the idle driving are satisfied. If the idling flag FK is 1, the idling interval Tint is calculated in S303. Blank hit interval Tint in S303
Is a characteristic part of the present invention, and is specifically performed based on the flowchart shown in FIG.

In the flowchart of FIG. 7, first, at S50
At step 1, the engine coolant temperature THW is read, and at step S502, an idling interval Tint given as a one-dimensional map for the engine coolant temperature THW is calculated. Here, the idling interval Tint is determined as follows based on FIG. 8 and FIG. FIG. 8 shows the engine coolant temperature THW.
And the ECU 7, which is a control unit, particularly shows the relationship between the injector drive circuit temperature, which tends to be high, and when the drive circuit temperature is predicted from the engine coolant temperature THW,
Considering the heat generation of the drive circuit itself, estimate at 25 ° C higher,
Drive circuit temperature = engine water temperature THW + 25 (° C.). FIG. 9B shows a limit value of a settable blanking cycle determined by a thermal load limit with respect to the injector drive circuit temperature predicted in this manner (dotted line in the figure), and a certain margin. It shows the set value (solid line in the figure) of the idle hitting cycle that is determined in anticipation.

As shown in FIG. 9A, the idle driving cycle to be set is a driving time Tq (a power supply time to the solenoid valve 1a).
And the blanking interval Tint (interval after turning off the power). In the present embodiment, the idle driving time Tq is a constant value, and the idle driving time Tq
Was subtracted from the set value of the blanking cycle, and the resulting value was defined as a blanking interval Tint. In S502 of FIG. 7, based on the one-dimensional map created in advance in this way, the idle shot interval Tin is calculated from the engine coolant temperature THW read in S501.
t will be calculated. If the blanking cycle is constant regardless of the temperature condition as in the related art, the blanking cycle (4350 μs) corresponding to the upper limit 100 ° C. of the drive circuit temperature.
However, by setting the idling cycle based on the drive circuit temperature predicted from the engine coolant temperature THW, the idling cycle at low temperatures can be set shorter, and the pressure can be effectively reduced. it can. FIG. 10 shows the difference in the idling cycle depending on the temperature condition in comparison with the operation at low temperature and the operation at high temperature.

In FIG. 5, in the following S304, a preset idle driving time Tq is read. The drive time Tq is appropriately set within a range shorter than the delay time tm, and is set to a constant value, for example, 320 μs in the present embodiment. Then, S
In 305, a pulse output (driving time Tq, idle shot interval Tint) for performing the idle shot driving is performed, and the present process ends. For example, in the idling control process executed at time t21 in FIG. 10, FKOLD = 0 in S301 and the idling flag FK is 1 in S302.
The process proceeds to 03 or later, and idle driving is performed. Then, the solenoid valve 1a of the injector 1 is opened for a predetermined drive time Tq to reduce the common rail pressure, and thereafter, the idle driving is stopped for the calculated idle interval Tint.

The idle hit control process according to the angle synchronization routine shown in FIG. 5 is for performing the first idle hit drive when the idle hit flag FK changes from 0 to 1;
An idling control process is performed according to an off interrupt routine of FIG. For example, at t21 in FIG. 10, after the idle driving control process by the angle synchronization routine of FIG. 5 is executed, when the energization to the solenoid valve 1a is stopped, the execution of this process is started, and
In 401, it is determined whether or not an idle hit flag FK is 1 to confirm whether or not a condition for performing the idle hit drive is satisfied. If the idle hit flag FK is not 1 in S401, this processing is terminated as it is, and if the idle hit flag FK is 1, in S402, the idle hit interval Tint
Read. The blanking interval Tint read here
Is calculated at the time of the first idle driving. Next, in S403, a preset idle driving time Tq is read, and in S404, a pulse output (driving time Tq, idle interval Tint) for performing idle driving is performed. Thus, after the first idle driving is performed at time t21 in FIG. 10, the set idle driving interval Tint
Is passed, idle driving by this processing is performed, and this processing ends once.

The idle driving control process by the off interrupt routine of FIG. 6 is continuously executed each time the power supply to the solenoid valve 1a is turned off, and until the idle driving flag FK becomes 0 in S401 (until time t4 in FIG. 10). ), Set drive time T
At q, the idle driving Tint is repeatedly performed. At this time, at time t31 in FIG. 10, the idle driving control process by the angle synchronization routine in FIG. 5 is executed.
As described above, since FKOLD becomes 1 in S301, it is determined that the idle driving control process is continuing, and the idle driving in this process is not performed. Note that the first idle driving was configured with the angle synchronization routine, and the subsequent idle driving with the power-off interrupt routine because the immediately preceding fuel injection and the first idle injection were close to each other and unexpectedly large amounts of fuel were injected. This is to prevent that.

As described above, in the present embodiment, the idling interval Tint at the time of executing the idling driving is configured to be changed at any time according to the engine coolant temperature THW, and as shown in FIG. For example, at a low temperature where there is a margin for the heat load, the idling cycle is set shorter than at a high temperature. Therefore, the blanking can be performed at the optimal blanking cycle according to the temperature condition, and the step-down performance can be maximized. The step-down performance is shown in FIG.
The leaked fuel leaking from the flow path 83 in the injector 1 to the flow path 53 in the above also contributes, and at low temperatures, the viscosity of the fuel increases and the leaked fuel decreases. For this reason, when idling is performed at the same cycle regardless of the temperature condition as in the related art, there is a problem that the pressure-reducing performance is deteriorated by the amount of the leaked fuel. If the driving cycle is shortened, the number of times of the non-driving driving per unit time is increased, and the pressure can be quickly reduced. Therefore, as shown in FIG. 10, the actual common rail pressure PC is changed to the target common rail pressure P
F, and there is an advantage that stable step-down performance can always be ensured.

FIGS. 11 to 15 show a second embodiment of the present invention. In the first embodiment, the idling driving time Tq is fixed, and the idling interval Tin is set.
Although t is changed according to the engine water temperature THW, in the present embodiment, the idle driving time Tq is changed according to the common rail pressure PC, and the idle interval Tint is changed according to the engine water temperature THW. .
The basic configuration and basic operation of the fuel injection device are the same as those of the first embodiment.
Since the third embodiment is the same as that of the first embodiment, only the portion related to the setting of the idle driving time Tq and the idle interval Tint is shown.

FIG. 11A is a diagram showing the first embodiment shown in FIG.
In S601 and S602, after confirming that the idle hit flag FKOLD is not 1 and the idle hit flag FK is 1, the idle drive time Tq is calculated in S603. The process of S603 is a characteristic part of the present embodiment, and instead of reading the preset idle driving time Tq, the idle driving time Tq is calculated based on the flowchart shown in FIG. In the flowchart of FIG. 12, first, in step S701, the actual common rail pressure PC is read, and in step S702, the idle driving time Tq given as a one-dimensional map for the actual common rail pressure PC is calculated.

When setting the idling driving time Tq, it is desirable to set the time as long as possible within the time during which fuel injection from the injector 1 into the engine cylinder does not occur, in order to ensure the pressure drop performance. . Idling driving time T
The parameters that affect q include cylinder pressure, common rail pressure, fuel temperature, power supply voltage, and the like. Further, variations among injectors and aging change also affect the fuel injection into the cylinder under any conditions. At present, the driving time Tq is set to be short so that there is no driving time. On the other hand, focusing on the actual common rail pressure PC which is constantly monitored during the operation of the engine, and examining the relationship of the idle driving time Tq, the longest idle driving that can be set according to the level of the actual common rail pressure PC is described. It has been found that the time Tq changes as shown in FIG.
Therefore, based on this, in S702 of FIG. 12, the optimum idle driving time Tq corresponding to the actual common rail pressure PC is determined.
Is calculated. After that, in S604, the empty beating Interpal T
Calculate int. This is shown in detail in FIG.
The engine coolant temperature THW is read in at step 1, and then the idling cycle Tcycl determined by the engine coolant temperature is calculated at S802. In step S803, the idle driving interval Tint is calculated by subtracting the idle driving time Tq calculated in step S603 from the idle driving cycle Tcycl.

In step S605 of FIG. 11A, an idle driving pulse is output, and the idle driving is performed at the calculated idle driving time Tq and the idle driving interval Tint. The subsequent idle driving is performed by a pulse-off interrupt routine shown in FIG. 11B. In the present embodiment, however, the common-rail pressure temporarily changes due to the idle driving, so that the idle driving time is again set in S613. After calculating Tq, and then reading the idle driving interval Tint in S613, the idle driving is performed in S614. FIG. 15 shows this series of operations.

Here, when the constant idle driving time Tq is set irrespective of the common rail pressure, the idle driving time at the common rail pressure of 48 MPa where the idle driving time Tq becomes the shortest is selected. On the high pressure side or low pressure side of the common rail pressure of 48 MPa, the step-down performance is reduced by the shortened idle driving time.
On the other hand, in the present embodiment, the actual common rail pressure P
Since the idle driving time Tq is set at any time according to C,
The idle driving control can be performed efficiently. Moreover,
As shown in FIG. 15, the idle driving time Tq is calculated every time the idle driving is performed.
Is calculated, and the optimal idle driving time Tq is always selected, so that the effect is high and the step-down performance can be maximized.

In each of the above embodiments, no particular indication is given as to which one of the four injectors 1 of the four-cylinder engine is used when performing the idling drive. Specifically, only the specific injector 1 is used. Instead, it is preferable to sequentially drive the plurality of injectors 1 to disperse the heat load. For example, in the example shown in FIG. 16A as the third embodiment, the idle driving from time t21 to t4 in FIG. 10 is performed by using the injectors 1 corresponding to the cylinders # 1 to # 4. Driving is performed in the order of # 1 → # 3 → # 4 → # 2. FIGS. 17 (a) and 17 (b) show flowcharts corresponding to the idle driving control processing in FIGS. 5 and 6, respectively.

FIG. 17A shows an angle synchronization routine executed every 180 ° CA, where the crank angle = 150 ° CA.
The signal is executed at the time t21 in FIG. 16A. S311 to S314 correspond to S3 in FIG.
This is the same as the processing from 01 to S304. If the idle hit flag FKOLD is not 1 and the idle hit flag FK is 1, the idle hit interval Tint is calculated based on the flowchart of FIG. The idle driving time Tq is read. In the following S315, the idle cylinder counter CCYLNK is set to 0. FIG. 17C shows the relationship between the idle cylinder counter CCYLNK and the idle cylinder. If CCYLNK = 0, the injector 1 corresponding to the # 1 cylinder is used. Next, S316
Then, a pulse output (driving time Tq, idle driving interval Tint) for performing the first idle driving is performed, and the present process ends.

Subsequent idle driving is performed by an off interrupt routine shown in FIG. S411 to S
Step 413 is the same as the processing from S401 to S403 in FIG. 6 described above. After confirming that the idling flag FK is 1, the calculated idling interval Tint and the preset idling driving time Tq are set. Read. S414 that follows
To update the idle cylinder counter CCYLNK (CCY
LNK = CCYLNK + 1), CC updated in S415
It is determined whether or not YLNK is 4 or less. Updated C
If CYLNK is 4 or less, the flow proceeds to S417 to perform the idling driving (driving time Tq, idling interval Tint), and if CCYLNK is larger than 4, CC in S416.
After setting YLNK to 0, the flow proceeds to S417 to perform idle driving. Thus, the idle driving is performed on the # 1 cylinder at time t21, and then the idle driving is repeatedly performed in the order of # 3 → # 4 → # 2. When the idling flag FK becomes 0 in S411 (time t4 in FIG. 16A), the process is terminated.

As described above, it is preferable to sequentially drive the plurality of injectors 1 because the thermal load applied to the injector drive circuit can be dispersed. At this time, as shown in FIG. 16A, the actual common rail pressure PC gradually decreases and reaches the target common rail pressure PF at time t4. Note that instead of setting CCYLNK = 0 in S315, CCYLNK is calculated using the immediately preceding injection cylinder CCYLN.
= CCYLN + 1.

Alternatively, FIGS. 16B and 16C show the fourth,
As shown in the fifth embodiment, a plurality of injectors 1 can be driven simultaneously. Here, the four injectors 1 are simultaneously driven. In this case, the idle driving cycle is the same as that of FIG. 16A, as shown in FIG. As shown in FIG.
(A) The period may be longer, for example, four times the idling period. FIGS. 18A and 18B are flowcharts of the idle driving control process corresponding to FIGS. 16B and 16C.

FIG. 18A shows an angle synchronization routine executed at every 180 ° CA.
If OLD is not 1 and the blank hit flag FK is 1 in S322, the process proceeds to S323 and the blank hit interval Tint
Is calculated. The blanking interval Tint is shown in FIG.
In the case of (b), the calculation is performed in the same manner as in FIG. 16A based on the flowchart of FIG. 7, and in the case of FIG.
The calculation is performed based on a map newly set so as to have a double idle period. Next, in S324, a preset idle driving time Tq is read, and in S325, a pulse output (driving time Tq, idle interval Tint) for performing the first idle driving is performed.

The off interrupt routine shown in FIG.
After confirming that the idling flag FK is 1 in S421, the actual common rail pressure PC is read in S422, and the target common rail pressure PF is read in S423. PC in S424
If -PF is larger than the predetermined pressure H, the idle driving interval calculated in S425 is read in advance in S426, and the idle driving time Tq set in advance is read in S426. Time Tq, blank shot interval Tint). This is called S424
Is repeated until PC-PF> H.

As described above, by simultaneously driving the four injectors 1, the pressure can be more quickly reduced to the target common rail pressure PF. At this time, FIG.
When the idle driving cycle is made the same as in FIG. 16A as shown in FIG. 16B, the time required for step-down is reduced and the step-down performance is improved, and the idle driving cycle is lengthened as shown in FIG. 16C. In this case, the heat load can be reduced although the step-down time is slightly longer.

Further, as in the sixth embodiment shown in FIG. 19, two injectors 1 may be alternately driven. Here, it is assumed that the two injectors 1 corresponding to the cylinders # 1 and # 4 and # 2 and # 3 are simultaneously driven as one group, respectively, and a flowchart of the idling control process in this case is shown in FIG. , (B).
If the idling cycle is the same as in FIG. 16A, the step-down time is shortened, and if it is longer than FIG. 16A, the thermal load can be reduced.

FIG. 20A is an angle synchronization routine executed every 180 ° CA. Steps S331 to S334 are the same as steps S311 to S314 in FIG. In the following S315, the idling cylinder group counter C
Set CYLNG to 0. The relationship between the idle cylinder group counter CCYLNG and the idle cylinder is shown in FIG. 20C. If CCYLNK = 0, the injectors 1 corresponding to the # 1 and # 4 cylinders are driven. Then, S31
In step 6, a pulse output (driving time Tq, idling interval Tint) for performing the first idling driving is performed, and the process ends.

Subsequent idle driving is performed by an off interrupt routine shown in FIG. S431 to S
Step 433 is the same as the processing from S411 to S413 in FIG. In subsequent S434, the idle-hit cylinder counter CCYLNG is updated (CCYLNG = CCYLNG +
1) It is determined whether or not CCYLNG updated in S435 is 1 or less. If the updated CCYLNG is 1 or less, the flow proceeds to S437 to perform the idling driving (driving time Tq, idling interval Tint). If CCYLNK is larger than 1, CCYLNG is set to 0 in S436.
Proceeding to S437, idle driving is performed. Thereby, # 1
And # 4, and two groups # 2 and # 3 alternately perform idle driving. In S431, idle hit flag F
When K becomes 0, the present process ends.

In each of the above embodiments, the water temperature sensor 71 is used as the temperature detecting means, and the injector drive circuit temperature is predicted from the engine water temperature THW. In addition, the injector drive circuit temperature is predicted based on the intake air temperature. The configuration may be such that Alternatively, both can be used.

In each of the above-described embodiments, for example, when the injection amount command value Q <0 and the actual common rail pressure PC> the target common rail pressure PF due to rapid deceleration, the method of reducing the pressure in the common rail 3 is described. As described above, the present invention may of course be applied to the case where the pressure in the common rail 3 becomes higher than necessary by restarting the engine after the high-load operation or by repeatedly turning on and off the starter switch. . In this case, the pressure reducing condition for reducing the fuel pressure in the common rail 3 is as follows.
For example, it is sufficient to confirm that the ignition switch and the starter switch have changed from the on state to the off state.
Thereafter, the pressure in the common rail 3 can be efficiently reduced by performing the idle driving in the same manner.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a pressure accumulating fuel injection device according to a first embodiment.

FIG. 2 is a diagram for explaining a valve opening operation of an injector.

FIG. 3 is a flowchart illustrating a common rail pressure control process executed in the first embodiment.

FIG. 4 is a flowchart illustrating an injector control process executed in the first embodiment.

FIG. 5 is a flowchart showing an idle hit control (angle synchronization) process executed in the first embodiment.

FIG. 6 is a flowchart illustrating idle control (off interrupt) processing executed in the first embodiment;

FIG. 7 is a flowchart illustrating details of an idle hit interval calculation process executed during a sixth process.

FIG. 8 is a diagram showing a relationship between an engine water temperature and an injector drive circuit temperature.

9A is a diagram illustrating a relationship between a blanking interval and a blanking period, and FIG. 9B is a diagram illustrating a relationship between a driving circuit temperature and a blanking period.

FIG. 10 is a diagram for explaining the operation of the first embodiment.

FIG. 11A is a flowchart showing an idling control (angle synchronization) process executed in the second embodiment, and FIG.
9 is a flowchart showing idle driving control (off interruption) processing.

FIG. 12 is a flowchart illustrating details of an idle hit interval calculation process executed during an eleventh process.

FIG. 13 is a flowchart illustrating details of an idle driving time calculation process executed during the eleventh process.

FIG. 14 is a diagram illustrating a relationship between a common rail pressure and an idle driving time.

FIG. 15 is a diagram for explaining the operation of the second embodiment.

FIGS. 16 (a), (b) and (c) are third, fourth and fifth.
It is a figure for demonstrating the effect | action of embodiment of each.

FIG. 17A is a flowchart illustrating idle control (angle synchronization) processing executed in the third embodiment, and FIG.
FIG. 7 is a flowchart showing idle control (off interrupt) processing, and FIG. 7C is a diagram showing a correspondence relationship between an idle cylinder counter and an idle cylinder.

FIG. 18A is a flowchart showing idle hit control (angle synchronization) processing executed in the fourth and fifth embodiments;
FIG. 4B is a flowchart showing the idling control (off interrupt) processing.

FIG. 19 is a diagram for explaining the operation of the sixth embodiment.

FIG. 20A is a flowchart showing idle hit control (angle synchronization) processing executed in the sixth embodiment, and FIG.
FIG. 8 is a flowchart showing idle control (off interrupt) processing, and FIG. 7C is a diagram showing a correspondence relationship between an idle cylinder group counter and an idle cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injector 11 Low pressure pump 1a Solenoid valve 15 Piping 23a, 25a Orifice 23b, 41, 45, 51 Flow path 27 Piston 3 Common rail (pressure accumulation chamber) 37 Nozzle needle (valve element) 43 Control chamber 47 Oil reservoir chamber 49 Injection hole 5 High pressure Pump (fuel supply pump) 7 ECU (control unit) 71 Water temperature sensor (temperature detecting means)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 37/00 F02M 37/00 C 51/00 51/00 A // F02M 55/02 350 55/02 350E (72) Inventor Hiroshi Haraguchi 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 3G066 AA07 AB02 AC01 AC09 AD12 BA12 BA19 BA22 CB07U CB16 CC06T CC14 CC26 CC64T CC67 CC70 CD25 CD26 CD29 CE22 DA02 DB01 DC04 DC05 DC09 DC13 DC14 DC18 3G301 HA02 HA04 HA06 JA14 JA37 KA01 LB06 LB11 LC01 LC10 MA28 NA03 NA06 NA08 NB14 NC04 ND04 NE23 PA10Z PB08A PB08Z PE01Z PE03Z PE08Z PF03Z

Claims (9)

[Claims] An accumulator for storing high-pressure fuel pumped from a fuel supply pump, an injector for injecting the high-pressure fuel in the accumulator into a cylinder of a diesel engine, and the fuel supply pump in accordance with an operation state of the diesel engine. And controlling the driving of the injector, comprising a control unit that injects fuel into the diesel engine and a temperature detection unit that directly or indirectly detects the temperature of the control unit. An injection section having a valve body for opening the valve by the pressure of the fuel supplied from the pressure accumulation chamber via the first flow path and injecting the fuel into the cylinder of the diesel engine, and a second flow path from the pressure accumulation chamber A drive unit that closes the valve body by the pressure of the fuel supplied through the valve, and fuel that is supplied to the drive unit from the accumulator by being opened and driven to the low pressure side of the fuel system. An electromagnetic valve for flowing, the valve body is configured to open with the opening of the electromagnetic valve, and the control unit controls the fuel in the accumulator chamber based on an operation state of the diesel engine. A condition satisfaction determining means for determining whether or not a pressure reducing condition for reducing pressure is satisfied; and opening the solenoid valve with a time width shorter than a delay time required for the valve body to open. Pressure-reducing means for performing driving for driving to overflow high-pressure fuel in the pressure storage chamber to the low-pressure side, and when the condition-determining means determines that the pressure-reducing condition is satisfied, the temperature is detected by the temperature detecting means. The cycle of the idling drive by the pressure reducing means is determined based on the temperature of the control section so that the heat load received by the control section does not exceed the limit, and the pressure reducing means is operated by the cycle to determine the pressure accumulation. Indoor fuel pressure An accumulator-type fuel injection device comprising a pressure-reduction executing means for decreasing the pressure. 2. The fuel injection means for injecting fuel into a cylinder of the diesel engine by driving the solenoid valve in synchronization with the rotation of the diesel engine by the control unit, and the pressure accumulation by the idle driving A fuel injection suspending means for suspending the fuel injection by the fuel injection means immediately after the indoor fuel pressure decreases and the condition satisfaction determining means determines that the pressure reducing condition is not satisfied. Item 7. An accumulator-type fuel injection device according to Item 1. 3. The temperature detecting means indirectly detects a temperature of a drive circuit of the injector in the control unit from at least one of a cooling water temperature and an intake air temperature of the diesel engine. 3. The pressure accumulating fuel injection device according to 2. 4. The pressure-accumulation fuel according to claim 1, wherein the pressure-decrease execution means determines a valve-opening drive time of the solenoid valve at the time of the idling drive according to the fuel pressure of the pressure-accumulation chamber. Injection device. 5. The diesel engine has a plurality of the cylinders, and a plurality of the injectors are provided for each of the cylinders, and the decompression means opens the solenoid valves of the injectors sequentially or at least two of them at the same time. The accumulator type fuel injection device according to any one of claims 1 to 4, which is driven. 6. An accumulator for storing high-pressure fuel pumped from a fuel supply pump, an injector for injecting the high-pressure fuel in the accumulator into a cylinder of a diesel engine, and the fuel supply pump according to an operation state of the diesel engine. And controlling the driving of the injector, comprising a control unit that injects fuel into the diesel engine and a temperature detection unit that directly or indirectly detects the temperature of the control unit. An injection section having a valve body for opening the valve by the pressure of the fuel supplied from the pressure accumulation chamber via the first flow path and injecting the fuel into the cylinder of the diesel engine, and a second flow path from the pressure accumulation chamber A drive unit that closes the valve body by the pressure of the fuel supplied through the valve, and fuel that is supplied to the drive unit from the accumulator by being opened and driven to the low pressure side of the fuel system. A pressure-accumulation type fuel injection device having an electromagnetic valve for flowing, wherein the valve element is configured to open in accordance with valve-opening drive of the electromagnetic valve; When it is established, the solenoid valve is driven to open with a time width shorter than the delay time required for the valve element to open, and the high pressure fuel in the pressure accumulating chamber overflows to the low pressure side by performing an idling drive. A method of controlling the pressure in the pressure accumulation chamber by flowing the temperature, wherein the temperature of the control unit is directly or indirectly detected, and based on the detected temperature, the heat load received by the control unit is limited. A method for controlling the pressure in the accumulator, wherein a period of the idling drive of the solenoid valve is determined so as not to exceed. 7. The pressure control method according to claim 6, wherein the fuel injection by the injector is stopped immediately after the fuel pressure in the accumulator drops and the idling drive of the solenoid valve is stopped. 8. The pressure control method according to claim 6, wherein the temperature of the control unit is indirectly detected from at least one of a cooling water temperature and an intake air temperature of the diesel engine. 9. A plurality of injectors are provided corresponding to each of the plurality of cylinders of the diesel engine, and the solenoid valves of these injectors are sequentially opened or two or more are simultaneously opened. The pressure control method according to any one of the above items.