JP2003322067A - Accumulator fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a accumulator fuel injection device capable of suppressing the cost of its ECU by making common an SCV driving circuit and a pressure reducing valve driving circuit of conventional type. <P>SOLUTION: In a control logic to control the fuel pressure in a common-rail by the ECU, the pump discharge amount control to boost the fuel pressure in the common-rail from a low pressure to a high and the pressure reducing valve flow rate control (fuel circulating amount control) to reduce the fuel pressure in the common rail from the high pressure to the low are feedback controlled with the same control pulse signals emitted from the SCV and the pressure reducing valve driving circuit. That is, the process from the boosting to pressure reduction in the fuel pressure control can be controlled with the control flow rate characteristics for one driving amperage, so that the pressure controllability of the ECU can be enhanced. Making common the SCV driving circuit and pressure reducing valve driving circuit of conventional type allows simplifying the constitution of the output circuit of the ECU to lead to cost-down of the ECU. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure accumulating fuel provided with a suction metering type fuel supply pump for pressurizing a fuel sucked into a pressurizing chamber through a suction metering valve to increase its pressure to a pressure accumulator. The present invention relates to an injection device, in particular, for accumulating high-pressure fuel discharged from a fuel supply pump, and for injecting fuel into a pressure accumulator container that distributes this accumulated high-pressure fuel to fuel injection valves mounted on each cylinder of an internal combustion engine. The present invention relates to a pressure-accumulation fuel injection device provided with a pressure reducing valve for reducing the pressure of fuel in a pressure accumulating container corresponding to the pressure from high pressure to low pressure.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection system for a diesel engine, a pressure accumulator (common rail) for accumulating high-pressure fuel corresponding to the fuel injection pressure, and high-pressure fuel in the common rail are injected and supplied into a cylinder of an internal combustion engine. BACKGROUND ART A pressure accumulation type fuel injection system including an electromagnetic fuel injection valve that operates and a suction metering type fuel supply pump (supply pump) that pressurizes a fuel sucked into a pressurizing chamber to increase the pressure to a common rail is known. ing.

In this pressure accumulating fuel injection system, the intake metering valve (SC) having excellent boosting performance for boosting the common rail pressure corresponding to the fuel injection pressure from low pressure to high pressure is used.
V) is built into the supply pump, for example, during acceleration,
It is configured to adjust the opening degree of a fuel supply passage that communicates the fuel tank and the pressurizing chamber, change the pump discharge amount discharged from the supply pump, and quickly raise the common rail pressure. In addition, a pressure reducing valve that reduces the common rail pressure corresponding to the fuel injection pressure from high pressure to low pressure is installed at the end of the common rail to open the fuel discharge passage that connects the common rail and the fuel tank during deceleration, for example. The common rail pressure is quickly reduced by opening the valve.

8 and 9 show a conventional SCV solenoid coil 1 by an electronic control unit (ECU).
01 and the solenoid coil 102 of the pressure reducing valve show the control logic for calculating the SCV drive current value and the pressure reducing valve drive current value, and FIG. 10 shows the control characteristics of the pump discharge amount with respect to the SCV drive current and the pressure reducing valve drive current and the pressure reducing valve. The control characteristics of the flow rate (fuel recirculation amount) are shown.

First, the method of calculating the SCV drive current value by the ECU 100 including the SCV drive circuit 103 is the required injection amount calculated using the required injection amount calculation map by the known PID (proportional integral derivative) control. (QFI
N) and the required fuel pressure (PFIN) calculated using the required fuel pressure calculation map and the actual fuel pressure (NPC) detected by the fuel pressure sensor, the required discharge amount (QPMP)
To calculate. Next, the SCV drive current value calculation map is used to calculate the SCV drive current value (IPMP) from the required discharge amount (QPMP) and the actual fuel pressure (NPC), and the SCV drive current is calculated through the SCV drive circuit 103. Is applied to the solenoid coil 101. As a result, the lift amount (valve opening) of the SCV is adjusted according to the SCV drive current value, so the pump discharge amount that is pumped from the supply pump to the common rail is changed according to the SCV drive current value. As a result, feedback control is performed so that the pump discharge amount (actual fuel pressure) substantially matches the required fuel pressure.

Further, the method of calculating the pressure reducing valve drive current value by the ECU 100 including the pressure reducing valve drive circuit 104 is a request calculated using a required fuel pressure calculation map by a known PID (proportional integral derivative) control. Fuel pressure (P
The required pressure reducing valve flow rate (QL) is calculated from FIN) and the actual fuel pressure (NPC) detected by the fuel pressure sensor. Next, the pressure reducing valve drive current value (IQL) is calculated from the required pressure reducing valve flow rate (QL) and the actual fuel pressure (NPC) by using the pressure reducing valve drive current value calculation map, and the pressure reducing valve drive circuit 104.
The pressure reducing valve drive current is supplied via the solenoid coil 1 of the pressure reducing valve.
02 is applied. As a result, the lift amount (valve opening) of the pressure reducing valve is adjusted according to the pressure reducing valve drive current value, so that the fuel recirculation amount returned from the common rail to the fuel tank is changed according to the pressure reducing valve drive current value.

[0007]

However, in the conventional pressure accumulation type fuel injection system, the controllability of the fuel pressure in the common rail is an important control item related to the controllability of the fuel injection amount, and the fuel pressure in the common rail is The supply pump has a built-in suction metering valve for quickly increasing the pressure from low pressure to high pressure, and a pressure reducing valve for quickly reducing the fuel pressure in the common rail from high pressure to low pressure is installed at the end of the common rail. The intake metering valve and the pressure reducing valve are adjusted by individual drive current values, and feedback control is performed so that the fuel pressure in the common rail substantially matches the required fuel pressure. Since they are controlled individually, the control logic becomes complicated as shown in FIGS. 8 and 9, and a drive circuit in the ECU 100 is also required individually. There is a problem that the cost is up.

[0008]

An object of the present invention is to reduce the cost of the control unit for controlling the fuel pressure in the pressure accumulating container by sharing the conventional first control valve drive circuit and second control valve drive circuit. An object of the present invention is to provide a pressure accumulating fuel injection device. Further, the controllability of the fuel pressure in the pressure accumulator by the control unit can be improved by controlling the pressure increase and decrease in the fuel pressure control in the pressure accumulator with the control flow rate characteristic for one control valve drive signal. An object is to provide a pressure accumulating fuel injection device.

[0009]

According to the invention as set forth in claim 1, it is set according to at least the fuel pressure in the pressure accumulator detected by the fuel pressure detecting means and the operating condition or operating state of the internal combustion engine. 1 for the control unit that calculates the same control valve drive signal according to the deviation from the required fuel pressure
By applying the same control valve drive signal calculated via one control valve drive circuit to the first pressure control valve and the second pressure control valve, it is possible to simplify the control logic. A first control valve drive circuit that applies a control valve drive signal to one pressure control valve and a second control valve drive circuit that applies the same control valve drive signal to a second pressure control valve can be made common and integrated. Therefore, the cost of the control unit can be reduced.

According to the second aspect of the present invention, the first pressure control valve and the second pressure control valve adjust the opening degree of the fuel supply passage and the opening degree of the fuel discharge passage. By providing the same solenoid coil that drives the second valve body in the valve opening direction or the valve closing direction, the control flow rate characteristic for one control valve drive signal can be increased from the pressure increase to the pressure reduction of the fuel pressure control in the accumulator. Therefore, the controllability of the fuel pressure in the pressure accumulator by the control unit can be improved.

According to the third aspect of the invention, the first solenoid coil for driving the first valve body of the first pressure control valve in the valve opening direction or the valve closing direction and the second valve body of the second pressure control valve. And a second solenoid coil for driving the valve in the valve opening direction or the valve closing direction are connected in series so as to be controlled by the same drive current value corresponding to the same control valve drive signal, or the same control valve drive signal For example, by connecting in parallel so that it can be controlled with the same drive voltage value,
The effects described in claims 1 and 2 can be further improved.

According to the invention of claim 4, a normally closed type solenoid valve is used as the first pressure control valve, and a normally open type solenoid valve is used as the second pressure control valve. Even if the power supply to the first solenoid coil is stopped, foreign matter is caught between the first valve body of the first pressure control valve and the valve hole forming the fuel supply passage, and the first valve body is closed. Without doing so, the first pressure control valve is closed abnormally, and the pump pressure feed amount that is pressure-fed by the fuel supply pump is excessively pressure-fed (for example, total amount pressure-fed), and the fuel supply pump, accumulator container, fuel injection valve, and high pressure It is conceivable that the fuel pressure in the system including piping may become abnormally high. In this case, since the second valve body of the second pressure control valve is fully opened when the second solenoid coil is de-energized, the first pressure control valve is closed as described above. The fuel pressure in the accumulator can be lowered even in the event of an abnormal failure. As a result, the abnormally high pressure in the system can be released, which results in fail-safe.

According to the invention of claim 5, the normally open type solenoid valve is adopted as the first pressure control valve and the second pressure control valve, so that the control valve drive circuit and the first and second solenoids are provided. The first valve body is fully opened and the first pressure control valve is fully opened when the energization of the first and second solenoid coils is stopped due to the disconnection of the wire harness connecting the coil or the control abnormality of the control unit. It becomes abnormal. Along with this, the pump pressure feed amount that is pressure fed from the fuel supply pump becomes excessive pressure feed (for example, full amount pressure feed),
The fuel pressure in the system including the fuel supply pump, the pressure accumulator, the fuel injection valve, and the high-pressure pipe becomes abnormally high. In this case, since the second valve body of the second pressure control valve is also in the fully open state when the power supply to the second solenoid coil is stopped, the opening of the first pressure control valve as described above is performed. The fuel pressure in the accumulator can be lowered even in the event of an abnormal failure. As a result, the abnormally high pressure in the system can be released, which results in fail-safe.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings. [Structure of First Embodiment] FIGS. 1 to 4 show a first embodiment of the present invention. FIG. 1 is a view showing the entire structure of a pressure-accumulation fuel injection system, and FIG. FIG. 3 is a diagram showing a logic, and FIG. 3 is a diagram showing an SCV and a pressure reducing valve drive circuit built in the ECU.

The pressure-accumulation fuel injection system of this embodiment is equivalent to the fuel injection pressure injected and supplied to each cylinder of an internal combustion engine (hereinafter referred to as an engine) such as a four-cylinder diesel engine mounted on a vehicle such as an automobile. Common rails 1 as accumulators for accumulating high-pressure fuel, and a plurality of (four in this example) electromagnetic fuel injection valves connected to the common rails 1 to inject fuel into each cylinder of the engine. (Injector) 2, fuel supply pump (supply pump) 3 that is rotationally driven by the engine, and electronic control unit (hereinafter referred to as ECU) as a control unit that electronically controls the plurality of injectors 2 and supply pumps 3.
10 and 10. In FIG. 1, only the injector 2 corresponding to one cylinder of the four-cylinder engine is shown, and the other cylinders are not shown.

It is necessary for the common rail 1 to continuously accumulate a high pressure corresponding to the fuel injection pressure. Therefore, the high pressure fuel accumulated in the common rail 1 is the high pressure pipe 1.
It is supplied from the supply pump 3 via 1. Further, in the common rail 1, a normally-open type decompression capable of adjusting the opening degree of the fuel discharge passage (fuel return passage) 13 to the fuel discharge passages (fuel return passage) 15 and 16 communicating with the fuel tank 5. A valve (corresponding to the second pressure control valve of the present invention) 7 is installed.

The injector 2 of each cylinder is connected to the downstream end of a plurality of high-pressure pipes 12 branching from the common rail 1, and a fuel injection nozzle for injecting fuel into each cylinder of the engine is housed in this fuel injection nozzle. The electromagnetic fuel injection valve includes an electromagnetic actuator that drives the nozzle needle in the valve opening direction and a needle biasing unit such as a spring that biases the nozzle needle in the valve closing direction.

The fuel injection from these injectors 2 to each cylinder of the engine is performed by energizing and energizing the injection control solenoid valve 4 as an electromagnetic actuator for controlling the pressure in the back pressure control chamber of the command piston connected to the nozzle needle. Electronically controlled by stopping energization. That is, while the injection control solenoid valve 4 of the injector 2 of each cylinder is open, the high pressure fuel accumulated in the common rail 1 is injected and supplied to each cylinder of the engine.

The supply pump 3 pressurizes the low-pressure fuel sucked from the fuel tank 5 through the filter 9 to a high pressure and pressure-feeds it to the common rail 1. For example, when accelerating or starting the engine, the fuel pressure in the common rail 1 is promptly increased. This is a suction metering type high-pressure supply pump that excels in boosting performance for boosting the so-called common rail pressure from low pressure to high pressure. The supply pump 3 has a well-known feed pump (low-pressure supply pump: low-pressure supply pump) that pumps low-pressure fuel from the fuel tank 5 by rotating the pump drive shaft with the rotation of the crankshaft of the engine.
(Not shown), a cam (not shown) rotationally driven by a pump drive shaft, a plurality of plungers (not shown) driven by the cams, and these plungers reciprocally slide in the cylinder. A plurality of pressurizing chambers (plunger chambers: not shown) that pressurize the fuel sucked in by the above, and a discharge valve (not shown) that opens when the fuel pressure in these pressurizing chambers rises above a predetermined value. And have.

Further, the supply pump 3 is provided with a leak port so that the internal fuel temperature does not become high, and the leak fuel from the supply pump 3 passes from the fuel return passage 14 to the fuel return passage 16. It is returned to the fuel tank 5. By adjusting the opening degree (opening degree) of the fuel passage in the fuel passage formed in the supply pump 3 and the fuel supply passage (not shown) from the feed pump to the pressurizing chamber, Intake metering valve (corresponding to the first pressure control valve of the present invention: SCV) 6 as a linear solenoid actuator that changes the amount of fuel discharged from the pump 3 to the common rail 1 (pump discharge amount, pump pressure feed amount) 6 Is attached.

SCV6 is an SCV, pressure reducing valve drive circuit 20
The amount of fuel sucked into the pressurizing chamber of the supply pump 3 is adjusted by being electronically controlled by the drive current value applied from the ECU 10 via the. This SCV6
Is a valve (corresponding to the first valve body of the present invention: not shown) that adjusts the opening of the fuel supply path for sending fuel from the feed pump into the pressurizing chamber, and a linear valve that drives the valve in the valve closing direction. A solenoid (first electromagnetic coil: corresponding to the first solenoid coil of the present invention) 21 and valve urging means (not shown) such as a spring for urging the valve in the valve opening direction.
have.

The SCV6 is, as shown in FIG.
The amount of high-pressure fuel discharged from the pressurizing chamber of the supply pump 3 to the common rail 1 in proportion to the magnitude of the drive current value applied to the linear solenoid 21 via the SCV and pressure reducing valve drive circuit 20 (pump The fuel pressure in the common rail 1, that is, the common rail pressure corresponding to the fuel injection pressure that is injected and supplied from each injector 2 into each cylinder of the engine is adjusted by adjusting the discharge amount).

The SCV6 of this embodiment is shown in FIG.
, The drive current value is the first predetermined value (for example, 1
A: It is a normally open type (normally open) solenoid valve in which the lift amount of the valve is maximum, that is, the valve is in the fully open state when it is I1a) or less. Moreover, SCV6 is shown in FIG.
As shown in (a), a predetermined value (I1b) larger than the first predetermined value and a predetermined value (for example, 2A: I1c, I1c> I).
1b), there is a control characteristic that the valve lift amount decreases and the pump discharge amount decreases as the drive current value increases.

The pressure reducing valve 7 is an SCV, pressure reducing valve drive circuit 20.
By being electronically controlled by the drive current value applied from the ECU 10 via the, the electromagnetic force excellent in step-down performance for rapidly reducing the fuel pressure in the common rail 1, so-called common rail pressure, from high pressure to low pressure during deceleration or engine stop is achieved. It is a valve. This pressure reducing valve 7 is common rail 1
A valve (corresponding to the second valve body of the present invention: not shown) for adjusting the opening degree of the fuel return path 13 for returning the fuel from the fuel tank 5 to the fuel tank 5, and driving the valve in the valve closing direction or the valve opening direction. A linear solenoid (second electromagnetic coil: corresponding to the second solenoid coil of the present invention) 22 and a valve urging means (not shown) such as a spring for urging the valve in the valve opening direction or the valve closing direction. is doing.

The linear solenoid 22 of the pressure reducing valve 7
As shown in FIG. 3, the SCV 6 and the pressure reducing valve 7 are
In order to make it possible to linearly variably control the valve opening with an SCV connected to the output circuit of the microcomputer of the ECU 10 and the same drive current value output from the pressure reducing valve drive circuit 20, it is connected in series to the linear solenoid 21 of the SCV 6. It is connected. As shown in FIG. 4B, the pressure reducing valve 7 is controlled from within the common rail 1 in proportion to the magnitude of the drive current value applied to the linear solenoid 22 via the SCV and pressure reducing valve drive circuit 20. Fuel return path 13, 15, 16
The common rail pressure is changed by adjusting the recirculation amount (flow rate of the pressure reducing valve) of the fuel recirculated to the fuel tank 5 via

The pressure reducing valve 7 of this embodiment is shown in FIG.
As shown in, the second predetermined value (minimum value, Min value: the drive current value is smaller than the above first predetermined value (for example, 1 A)).
For example, it is a normally open type solenoid valve in which the valve lift amount is maximum when the value is 0 A) or less, that is, the valve is in the fully open state, and when the drive current value is the maximum value Is the maximum, that is, the solenoid valve is in the fully open state.

As shown in FIG. 4 (b), the pressure reducing valve 7 has a second predetermined value (Min value: I2a) and a third predetermined value (I2b: I2b> I2a) larger than the second predetermined value. ,
When I2b <I1b), the valve drive amount decreases as the drive current value increases, and the pressure reducing valve flow rate (fuel recirculation amount) decreases. further,
As shown in FIG. 4B, the pressure reducing valve 7 has a fourth predetermined value (I2c: I2c> I1) larger than the third predetermined value.
Between c) and the maximum value (Max value: I2d), as the drive current value increases, the valve lift amount increases and the pressure reducing valve flow rate (fuel recirculation amount) also increases.

The ECU 10 includes a CPU that performs control processing and arithmetic processing, a storage device (memory such as ROM and RAM) that stores various programs and data, an input circuit, an output circuit, a power supply circuit, and an injector drive circuit (EDU) 24.
There is provided a microcomputer having a well-known structure configured to include such functions as. The sensor signals from the various sensors are A / D converted by the A / D converter and then input to the microcomputer. The SCV and pressure reducing valve drive circuit 20 described above are connected to the output circuit of the microcomputer.

Then, the ECU 10 uses the rotation speed sensor 3
Engine speed (NE) detected by 1 and the accelerator opening (A) detected by the accelerator opening sensor 32.
CCP) and the required injection amount (QFIN) set according to
And an engine speed (N
E) and the required injection amount (QFIN), the required injection timing (T
(FIN) injection timing determination means, an injection period for calculating a command injection pulse time (TQ) from the required injection amount (QFIN) and the actual fuel pressure (= common rail pressure: NPC) detected by the fuel pressure sensor 35. Decision means,
Injector drive means for applying a pulsed injector drive current to the injection control solenoid valve 4 of the injector 2 of each cylinder via an injector drive circuit (EDU) 24.

Then, the ECU 10 calculates the optimum fuel injection pressure according to the operating condition or operating state of the multi-cylinder engine, and through the SCV and the pressure reducing valve drive circuit 20, the linear solenoid 21 of the SCV 6 and the linear solenoid of the pressure reducing valve 7. It has a control flow rate control means for driving the solenoid 22. That is, the ECU 10 determines the required fuel pressure (PFI) according to the required injection amount (QFIN) and the engine speed (NE).
N) is calculated, and in order to achieve this required fuel pressure (PFIN), the drive current value (=) applied to the linear solenoid 21 of the SCV 6 and the linear solenoid 22 of the pressure reducing valve 7 (=
SCV + pressure reducing valve drive current value) to adjust the amount of fuel discharged from the supply pump 3 into the common rail 1 (pump discharge amount) or the flow rate of the pressure reducing valve to recirculate from the common rail 1 to the fuel tank 5 (fuel recirculation amount). Is configured to control.

Further, more preferably, for the purpose of improving the control accuracy of the fuel injection amount, the common rail pressure detected by the fuel pressure sensor 35 (hereinafter referred to as the actual fuel pressure:
It is desirable to feedback control the drive current value to the linear solenoid 21 of the SCV 6 and the linear solenoid 22 of the pressure reducing valve 7 by PID control so that NPC) substantially matches the required fuel pressure (PFIN). In addition,
The control of the drive current value (= SCV + pressure reducing valve drive current value) to the linear solenoid 21 of the SCV 6 and the linear solenoid 22 of the pressure reducing valve 7 is preferably performed by duty (DUTY) control. That is, the actual fuel pressure (NP
CV and the required fuel pressure (PFIN) according to the deviation (ΔP), the ON / OFF ratio (energization time ratio / duty ratio) of the control pulse signal per unit time is adjusted to adjust the SCV.
By using the duty control that changes the valve opening of the pressure reducing valve 6 and the pressure reducing valve 7, it is possible to perform highly accurate digital control.

Here, the ECU 10 of this embodiment, as shown in the control logic of FIG.
E) and an injection amount determining means for calculating a required injection amount (QFIN) according to the accelerator opening (ACCP), and a required fuel pressure (PFIN) according to the required injection amount (QFIN) and the engine speed (NE). ) For calculating fuel pressure, engine speed (NE) and actual fuel pressure (NPC)
Injector leak amount calculation means for calculating an injector leak amount (QLEAK) according to the fuel temperature (THF) and the injector leak amount (QLEAK), required fuel pressure (PFIN) and required injection amount (QFIN) Demand control flow rate determining means for calculating the demand control flow rate (QPMP), actual fuel pressure (NPC) and demand control flow rate (QPM)
P) and the drive current value determining means for calculating the drive current value (IPMP) according to the SCV + pressure reducing valve drive current value calculation map, the actual fuel pressure (NPC) and the required fuel pressure (PFIN).
And the feedback correction amount (IF
And a correction amount determining means for calculating B). In addition,
Required injection amount (QFIN), required fuel pressure (PFIN)
May be calculated in consideration of a correction amount such as the cooling water temperature (THW) detected by the cooling water temperature sensor 33 or the fuel temperature (THF) detected by the fuel temperature sensor 34.

[Control Method of First Embodiment] Next, a control method of a drive current value (= SCV + pressure reducing valve drive current value) to the linear solenoid 21 of the SCV 6 and the linear solenoid 22 of the pressure reducing valve 7 of the present embodiment will be described. A brief description will be given with reference to FIGS. 1 to 4.

The ECU 10 controls the engine speed (NE) detected by the rotation speed sensor 31 and the accelerator opening (ACC) detected by the accelerator opening sensor 32.
P) to the basic injection amount (Q) set by the cooling water temperature (THW) detected by the cooling water temperature sensor 33 and the fuel temperature (TH) detected by the fuel temperature sensor 34.
F) and other injection amount correction amounts are added, the required injection amount (QFI
N) is calculated (injection amount determination means). In addition, the ECU 10
Is the required injection amount (QFIN) and the engine speed (N
The required fuel pressure (PFIN) is calculated by (E) and (fuel pressure determining means).

Here, the linear solenoid 21 of SCV6
And the drive current value (= SCV + pressure reducing valve drive current value) applied to the linear solenoid 22 of the pressure reducing valve 7 to a known PI
A method of calculating using D (proportional integral derivative) control will be described.

The ECU 10 conducts experiments beforehand on the relationship between the engine rotation speed (NE) detected by the rotation speed sensor 31, the actual fuel pressure (NPC) detected by the fuel pressure sensor 35, and the reference value of the injector leak amount. The reference value of the injector leak amount is calculated by using the characteristic map or the arithmetic expression created by the calculation. Next, the injector leak amount (QLEAK) is calculated by multiplying the reference value of the injector leak amount by the fuel temperature correction coefficient in consideration of the fuel temperature (THF) detected by the fuel temperature sensor 34 (injector leak amount calculation means). ).

Next, the required injection amount (QFIN), the required fuel pressure (PFIN) and the injector leak amount (QLEA).
The required control flow rate (QPMP) is calculated using a characteristic map or an arithmetic expression created by previously obtaining the relationship between K) and the required control flow rate (QPMP) by experiments or the like (request control flow rate determination means). Next, based on the SCV + pressure reducing valve drive current value calculation map created by previously measuring the relationship between the required control flow rate (QPMP), the actual fuel pressure (NPC) and the drive current value (IPMP), the drive current is calculated. The value (IPMP) is calculated (driving current amount determining means).

Further, the ECU 10 determines that the actual fuel pressure (NP
C) and required fuel pressure (PFIN) deviation (= ΔP) and feedback gain (proportional gain Kp, integral gain K
i, differential gain Kd) based on a feedback gain map created by previously measuring the relationship with
Feedback gain (proportional gain Kp, integral gain K
i, differential gain Kd) is calculated. And the following number 1
The feedback correction amount (IFB) is calculated on the basis of the arithmetic expression of (correction amount determination means).

[Equation 1] However, ΔP is a deviation between the required fuel pressure (PFIN) and the actual fuel pressure (NPC).

Then, the ECU 10 calculates the final drive current value (IPMP) by adding the drive current value (IPMP) and the feedback correction amount (IFB) based on the following equation (2).

[Equation 2]

Then, the ECU 10 converts the final drive current value (IPMP) into a control pulse signal (pulse-shaped pump drive signal) using a predetermined conversion coefficient in a DUTY generation circuit (not shown). . Then, the ECU 10
A pulsed pump drive signal is applied to the linear solenoid 21 of the SCV 6 and the linear solenoid 22 of the pressure reducing valve 7 via the SCV and the pressure reducing valve drive circuit 20.

As a result, when the common rail pressure is increased from low pressure to high pressure when the engine is started or accelerated, the lift amount of the valve of the SCV 6 (opening of the fuel supply passage).
Is adjusted from the pressurizing chamber of the supply pump 3 to the high-pressure pipe 1.
1, the amount of high-pressure fuel that is pressurized and pressure-fed to the common rail 1 is controlled, and the pump discharge amount and the fuel pressure in the common rail 1 (= actual fuel pressure NPC) are the required fuel pressure (P
The feedback control is performed so as to substantially match FIN).

When the common rail pressure is reduced from high pressure to low pressure during deceleration or engine stop, the valve lift of the pressure reducing valve 7 (opening of the fuel discharge path) is adjusted so that the fuel from the common rail 1 is reduced. The amount of fuel recirculated to the fuel tank 5 via the recirculation path 13 is controlled, and feedback control is performed so that the fuel pressure in the common rail 1 (= actual fuel pressure NPC) substantially matches the required fuel pressure (PFIN).

[Effects of First Embodiment] As described above, EC
In the control logic for feedback-controlling the fuel pressure in the common rail 1 by U10, the pump discharge amount control for raising the fuel pressure in the common rail 1 (= actual fuel pressure NPC) from low pressure to high pressure, and the fuel pressure in the common rail 1 (= The pressure reducing valve flow rate control (fuel recirculation amount control) for reducing the actual fuel pressure NPC) from the high pressure to the low pressure is feedback-controlled by the same control pulse signal output from the SCV and the pressure reducing valve drive circuit 20.

That is, from the pressure increase to the pressure decrease of the fuel pressure control in the common rail 1, as shown in FIG.
Since the control flow rate characteristic for one drive current value can be used for control, the controllability of the fuel pressure in the common rail 1 by the ECU 10 can be improved. Further, by sharing the conventional SCV drive circuit and the pressure reducing valve drive circuit, the ECU 10
The configuration of the output circuit of the microcomputer can be simplified, and the cost of the ECU 10 can be reduced.

A normally open type SCV6
And the pressure reducing valve flow characteristic is 0A of the drive current value and the maximum value (Ma
(x value) is combined with the pressure reducing valve 7 that maximizes the flow rate of the pressure reducing valve, thereby disconnecting the SCV, the wire harness connecting the pressure reducing valve drive circuit 20 and the linear solenoids 21 and 22, or the disconnection of the linear solenoid 21, or the ECU 1.
When the drive current value to the linear solenoids 21 and 22 is 0 A due to the control abnormality of 0, the valve of the SCV 6 may be in the fully open state, and the SCV 6 may be in the fully open abnormality.

Along with this, the amount of pumping pressure fed from the pressurizing chamber of the supply pump 3 becomes excessive pressure feeding (for example, total amount pressure feeding), and the fuel in the system including the common rail 1, the injector 2, the supply pump 3, and the high-pressure pipe 11 is fed. The pressure becomes abnormally high. In this case, the linear solenoid 2
When the drive current value of 2 is 0 A, the valve of the pressure reducing valve 7 is also in the fully open state, so that the fuel pressure in the common rail 1 can be lowered even in the case of the abnormal valve opening failure of the SCV 6 as described above. . As a result, the abnormally high pressure in the system can be released, which results in fail-safe.

[Second Embodiment] FIG. 5 shows a second embodiment of the present invention. FIG. 5A is a characteristic diagram showing a pump discharge amount characteristic with respect to a drive current value, and FIG. 5A is a characteristic diagram showing a pressure reducing valve flow rate (fuel recirculation amount) characteristic with respect to a drive current value, and FIG. 5C is a characteristic diagram showing a control flow rate characteristic with respect to a drive current value.

In this embodiment, the SCV6 is set to SC when the same drive current value is the first predetermined value (for example, 2 A) or more.
The V6 valve adopts a normally closed type (normally closed type) solenoid valve that fully opens the fuel supply passage.
Further, as the pressure reducing valve 7, when the same drive current value is equal to or less than a second predetermined value (for example, 0 A) smaller than the first predetermined value, the pressure reducing valve 7 makes the opening degree of the fuel discharge passage fully open. A type (normally open type) solenoid valve is used.

The SCV6 linear solenoid 21
Is to enable the SCV 6 and the pressure reducing valve 7 to linearly variably control the valve opening with the same drive current value output from the SCV and the pressure reducing valve drive circuit 20 connected to the output circuit of the microcomputer of the ECU 10. And is connected in series to the linear solenoid 22 of the pressure reducing valve 7. Also, S
As shown in FIG. 5A, CV6 has a minimum value (Min
Value: For example, a predetermined value (I1a) larger than 0A and the first
It has a control characteristic that the valve lift amount increases and the pump discharge amount increases as the drive current value increases between a predetermined value (for example, 2A: I1b).

As shown in FIG. 5B, the pressure reducing valve 7 has a second predetermined value (Min value: I2a) and a predetermined value (I2b: I2b> I2a, I2a) larger than the second predetermined value.
Between b <I1a), as the drive current value increases, the valve lift amount decreases, and the pressure reducing valve flow rate (fuel recirculation amount) decreases.

With the above configuration, the linear solenoid 21
Even if the drive current value to the valve is 0 A, foreign matter is caught between the valve of the SCV6 and the valve hole forming the fuel supply passage, and S
The CV6 does not close, and the SCV6 becomes closed abnormally. With this, the pump pressure feed amount pumped from the pressurizing chamber of the supply pump 3 becomes excessive pressure feed (for example, full amount feed), and the common rail 1, the injector 2, the supply pump. It is conceivable that the fuel pressure in the system including 3 and the high-pressure pipe 11 becomes abnormally high.

In this case, if the drive current value to the linear solenoid 22 is at least a predetermined value (A) larger than the second predetermined value (of course, the linear solenoid 22
(The drive current value to 0) and the valve of the pressure reducing valve 7 are fully opened, so that the fuel pressure in the common rail 1 is lowered even in the case of the abnormal valve closing failure of the SCV 6 as described above. be able to. As a result, the abnormally high pressure in the system can be released, which results in fail-safe. Further, similarly to the first embodiment, since the pressure increase to the pressure decrease of the fuel pressure control can be controlled by the control flow rate characteristic with respect to one drive current value as shown in FIG.
The controllability of the fuel pressure in the common rail 1 by 10 can be improved.

[Third Embodiment] FIG. 6 shows a third embodiment of the present invention, showing an SCV and a pressure reducing valve drive circuit.

In this embodiment, the linear solenoid 21 that drives the valve of the SCV 6 in the valve opening direction or the valve closing direction and the linear solenoid 22 that drives the valve of the pressure reducing valve 7 in the valve opening direction or the valve closing direction are connected to the ECU 10. The SCV connected to the output circuit of the microcomputer and the valve opening degree are connected in parallel so that the valve opening degree can be linearly variably controlled by the same drive voltage value output from the pressure reducing valve drive circuit 20.

[Fourth Embodiment] FIG. 7 shows a fourth embodiment of the present invention and is a diagram showing an SCV and pressure reducing valve drive circuit.

In this embodiment, the SCV connected to the output circuit of the microcomputer of the ECU 10, the SCV6 valve and the pressure reducing valve which are linearly driven by the same drive current value or the same drive voltage value output from the pressure reducing valve drive circuit 20. In order to be able to variably control the valve opening of the No. 7 valve, S
A linear solenoid 23 that drives the valve of the CV 6 in the valve opening direction or the valve closing direction and drives the valve of the pressure reducing valve 7 in the valve opening direction or the valve closing direction is provided. In this case, it is desirable to arrange the SCV 6 and the pressure reducing valve 7 close to each other.

[Modification] In this embodiment, the present invention is applied to PI.
By the D (proportional-integral-derivative) control, the method of feedback controlling the drive current value (∝ drive DUTY) or drive voltage value applied to the linear solenoid 21 of the SCV 6 and the linear solenoid 22 or the linear solenoid 23 of the pressure reducing valve 7 was applied. According to the present invention, the linear solenoid 21 of the SCV 6 and the linear solenoid 2 of the pressure reducing valve 7 are controlled by PI (proportional integral) control or PD (proportional differential) control.
Alternatively, the drive current value (∝drive duty) or drive voltage value applied to the linear solenoid 23 or the linear solenoid 23 may be feedback-controlled.

In this embodiment, the injector leak amount (Q
LEAK), fuel temperature (THF), actual fuel pressure (NP)
The required control flow rate (QPMP) is calculated from C) and the required fuel pressure (PFIN), and the drive current value (IPMP) is obtained from the required control flow rate (QPMP), the actual fuel pressure (NPC), and the SCV + pressure reducing valve drive current value map. Is calculated and the feedback correction amount (IFB) is added to this drive current value (IPMP) to obtain the final drive current value (IPMP). However, the required injection amount (QFIN) and the required fuel pressure ( PFIN) and drive DUTY map from drive DUTY
(%) Is calculated, the feedback correction amount (FBDUTY) is added to this drive DUTY (%), and the final drive DUTY is applied to the linear solenoid 21 of the SCV 6 and the linear solenoid 22 or the linear solenoid 23 of the pressure reducing valve 7. (%) May be obtained. This arithmetic expression is shown in the following Equations 3 and 4.

[Equation 3] However, ΔP is (PFIN-NPC).

[Equation 4] The drive DUTY (%) and FBDUTY (%) may be calculated as the drive current value (A) and the correction current value (A).

Further, the present invention may be used for the following PID control. The feedback pressure amount (PFB) is calculated by the known PID control using the deviation (ΔP) between the required fuel pressure (PFIN) and the actual fuel pressure (NPC). This arithmetic expression is shown in the following Expression 5.

[Equation 5]

In this feedback pressure amount (PFB),
The feedback elastic fuel amount (QFB) is calculated by multiplying the bulk elastic coefficient (Kα) by the value obtained by dividing the volume of the common rail (V). Next, the feedback fuel amount (QFB), the injector leak amount (QLEAK), and the required injection amount (QFI).
N) is added to calculate the required control flow rate (QPMP),
The required control flow rate (QPMP) is multiplied by a predetermined conversion coefficient to calculate the linear solenoid 21 of the SCV 6 and the pressure reducing valve 7.
The drive current value (IPMP) applied to the linear solenoid 22 or the linear solenoid 23 is calculated.

In this embodiment, an electromagnetic SCV (first pressure control valve) in which the lift amount (valve opening) of the first and second valves is changed by a solenoid coil whose magnetomotive force increases and decreases according to the amount of energization 6 and electromagnetic pressure reducing valve (second pressure control valve) 7
However, the electric first pressure control valve or the second electric pressure control valve in which the lift amount of the first and second valves is changed by the electric motor whose rotation angle or rotation speed changes according to the energization amount May be adopted.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of a pressure-accumulation fuel injection system (first embodiment).

FIG. 2 is a diagram showing a control logic of the ECU (first
Example).

FIG. 3 is a circuit diagram showing an SCV and a pressure reducing valve drive circuit built in an ECU (first embodiment).

4A is a characteristic diagram showing a pump discharge amount characteristic with respect to a drive current value, FIG. 4B is a characteristic diagram showing a pressure reducing valve flow rate (fuel recirculation amount) characteristic with respect to a drive current value, and FIG. FIG. 3 is a characteristic diagram showing a control flow rate characteristic with respect to a drive current value (first embodiment).

5A is a characteristic diagram showing a pump discharge amount characteristic with respect to a driving current value, FIG. 5B is a characteristic diagram showing a pressure reducing valve flow rate (fuel recirculation amount) characteristic with respect to a driving current value, and FIG. FIG. 6 is a characteristic diagram showing a control flow rate characteristic with respect to a drive current value (second embodiment).

FIG. 6 is a circuit diagram showing an SCV and pressure reducing valve drive circuit built in an ECU (third embodiment).

FIG. 7 is a circuit diagram showing a SCV and pressure reducing valve drive circuit built in an ECU (fourth embodiment).

FIG. 8 is a diagram showing a control logic of an ECU (prior art).

FIG. 9 is a circuit diagram showing an SCV drive circuit and a pressure reducing valve drive circuit incorporated in an ECU (prior art).

10A is a characteristic diagram showing a pump discharge amount characteristic with respect to a drive current value, and FIG. 10B is a characteristic diagram showing a pressure reducing valve flow rate (fuel recirculation amount) characteristic with respect to a drive current value (conventional). Technology).

[Explanation of symbols]

1 common rail (accumulation container) 2 injectors (electromagnetic fuel injection valve) 3 supply pumps (fuel supply pumps) 6 SCV (first pressure control valve, suction metering valve) 7 Pressure reducing valve (second pressure control valve) 10 ECU (control unit) 20 SCV, pressure reducing valve drive circuit 21 Linear solenoid (first solenoid coil) 22 Linear solenoid (second solenoid coil) 23 Linear solenoid (same solenoid coil) 35 Fuel pressure sensor (fuel pressure detection means)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 55/02 350 F02M 55/02 350E 59/36 59/36

Claims (5)

[Claims] 1. A pressure accumulator container for accumulating high-pressure fuel corresponding to a fuel injection pressure, and distributing and supplying the accumulated high-pressure fuel to a plurality of fuel injection valves mounted on each cylinder of an internal combustion engine, (B) a fuel supply pump that pressurizes the fuel sucked into the pressurizing chamber and pumps it into the accumulator, and (c) adjusts the opening degree of the fuel supply passage for supplying the fuel into the pressurizing chamber. An electric or electromagnetic first pressure control valve for increasing the fuel pressure in the pressure accumulator from a low pressure to a high pressure, and (d) adjusting the opening degree of the fuel discharge passage for discharging the fuel from the pressure accumulator. Then, the second electric or electromagnetic type for reducing the fuel pressure in the accumulator from a high pressure to a low pressure
A pressure control valve; (e) fuel pressure detection means for detecting fuel pressure in the pressure accumulator; (f) fuel pressure in the pressure accumulator detected by at least the fuel pressure detection means and operation of the internal combustion engine. One control valve drive for applying the same control valve drive signal calculated according to the deviation from the required fuel pressure set according to the condition or operating state to the first pressure control valve and the second pressure control valve And a control unit having a circuit. 2. The pressure-accumulation fuel injection device according to claim 1, wherein the first pressure control valve includes a first valve body that adjusts an opening degree of the fuel supply passage, and the second pressure control valve. Has a second valve body that adjusts the opening degree of the fuel discharge passage, and the first pressure control valve and the second pressure control valve open the first valve body and the second valve body in a valve opening direction. Alternatively, a pressure accumulating fuel injection device having the same solenoid coil that is driven in a valve closing direction. 3. The pressure-accumulation fuel injection device according to claim 1, wherein the first pressure control valve is a first valve body that adjusts an opening degree of the fuel supply passage, and opens the first valve body. Direction, or a first solenoid coil for driving in a valve closing direction, the second pressure control valve adjusts the opening degree of the fuel discharge passage, a second valve body, and a direction in which the second valve body opens. A pressure-accumulation fuel injection device comprising a second solenoid coil that is driven in a valve closing direction and that is connected in series or in parallel with the first solenoid coil. 4. The pressure-accumulation fuel injection device according to claim 3, wherein the first pressure control valve has a first drive current value or a same drive voltage value corresponding to the same control valve drive signal.
The first valve element is a normally-closed type electromagnetic valve in which the first valve element is fully opened when the value is equal to or more than a predetermined value, and the second pressure control valve has the same drive current value or the same drive voltage value. 2nd less than 1 predetermined value
A pressure-accumulation fuel injection device, characterized in that the second valve element is a normally open type electromagnetic valve in which the second valve element is in a fully opened state when the value is equal to or less than a predetermined value. 5. The pressure-accumulation fuel injection device according to claim 3, wherein the first pressure control valve has a first drive current value or a same drive voltage value corresponding to the same control valve drive signal.
It is a normally open type solenoid valve in which the first valve body is in a fully open state when the value is a predetermined value or less, and the second pressure control valve has the same drive current value or the same drive voltage value. 2nd less than 1 predetermined value
A pressure-accumulation fuel injection device, characterized in that the second valve element is a normally open type electromagnetic valve in which the second valve element is in a fully opened state when the value is equal to or less than a predetermined value.