JPH10227268A - Accumulator fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent stop of an engine even when a pressure sensor for detecting the pressure in a common rail has a trouble. SOLUTION: When a pressure sensor 9 is judged to be in an abnormal state, a rearl common rail pressure Pc is estimated by a current (i) flowing in a solenoid valve 11 and an engine 2 is continued to operate by using this estimated real common rail pressure Pc . Thereby, as a vehicle is not stopped at the same time as the trouble of the pressure sensor 9, when an occupant is informed by a warning means 16 of the trouble in the pressure sensor 9, he can bring the vehicle in an automobile dealer or garage by running the vehicle.

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 injection device applied to a diesel engine (diesel internal combustion engine), and is effective for use in a vehicle driving diesel engine.

[0002]

2. Description of the Related Art A pressure-accumulation fuel injection device stores fuel pressurized to about 100 to 135 MPa in a pressure accumulator (common rail) disposed upstream of a fuel injection valve (injector), and has an accelerator opening degree and The injector is opened according to the engine speed or the like, and fuel is injected into each cylinder. Therefore, in order to perform appropriate fuel injection, it is necessary to maintain the pressure in the common rail within a predetermined range.

Therefore, as described in JP-A-4-234562, pressure detection means such as a pressure sensor is provided on the common rail, and the pressure in the common rail falls within a predetermined range based on a signal from the pressure detection means. So that the fuel pump is controlled.

[0004]

By the way, according to the above-mentioned publication, when the pressure detecting means fails for some reason, in order to prevent the pressure in the common rail from rising, the pressure reducing valve is used when the pressure detecting means fails. To reduce the pressure in the common rail and stop the engine.

However, in the case of a diesel engine for driving a vehicle, if the engine stops, the vehicle must be stopped at that time (location). There is a possibility that a problem such as congestion which may have a great effect on a third party may occur. In view of the above, it is an object of the present invention to prevent an engine from stopping even when a pressure detecting unit fails.

[0006]

The present invention uses the following technical means to achieve the above object. According to the first aspect of the present invention, when the determination means (S140) determines that the pressure detection means (9) is in an abnormal state, the fuel pump (5) is operated based on a predetermined program set in advance. It is characterized by making it.

Thus, even if the pressure detecting means (9) is determined to be in an abnormal state, the internal combustion engine can be operated on the basis of a predetermined program set in advance. There is no need to stop the vehicle simultaneously with the failure of (9). Therefore, the occupants of the vehicle
When the failure of the pressure detecting means (9) is known, the vehicle can be driven and brought to an automobile dealer or a repair shop, etc., thereby preventing traffic congestion and the like from greatly affecting third parties. can do.

By the way, in a device such as an electromagnetic valve that operates a movable portion by an electromagnetic attraction force, a current flowing through the electromagnetic valve when the movable portion moves (instantaneously) is generated before the movable portion moves, as described later. It changes greatly in comparison. Therefore, if the current flowing through the solenoid valve when the movable part moves can be detected, the electromagnetic attraction force acting on the movable part when the movable part moves can be obtained from the detected current. Therefore, if the electromagnetic attraction force acting on the movable portion is determined, the pressure acting on the solenoid valve can be estimated from the detected current, as described later.

In view of the above, in the invention according to the second to fourth aspects, when the determining means (S140) determines that the pressure detecting means (9) is in an abnormal state, the driving means (13) Drives the solenoid valve (11) to estimate the pressure in the pressure accumulator (6) based on the value detected by the current detecting means (12) and the value stored in the storage means (ROM). 6) The fuel pump (5) is operated so that the pressure in the inside becomes a predetermined value.

Thus, the pressure in the accumulator (6) can be estimated based on the value detected by the current detecting means (12) and the value stored in the storage means (ROM). If the fuel pump (5) is operated based on the pressure, the internal combustion engine can be continuously operated. Therefore, it is not necessary to stop the vehicle at the same time as the failure of the pressure detecting means (9), so that the same effect as that of the first aspect can be obtained.

According to the third aspect of the present invention, the inside of the pressure accumulating vessel (6) and the suction side of the fuel pump (5) may be communicated by the solenoid valve (11). Further, when the detected value of the pressure detecting means (9) is out of a predetermined range, it is determined that the pressure detecting means (9) is in an abnormal state. You may do it.

According to the invention described in claim 5, the solenoid valve (1)
1) A driving means (13) for driving, a current detecting means (12) for detecting a current flowing through the solenoid valve (11), and an action on the movable part (11e) corresponding to the current flowing through the solenoid valve (11). And a storage means (ROM) for storing the electromagnetic attraction force. Thus, as described above, the pressure in the pressure accumulator (6) can be estimated without using pressure detecting means such as a pressure sensor. Therefore,
According to the pressure accumulating fuel injection device provided with the present invention, even when a failure occurs in the pressure detection unit, the internal combustion engine can be operated without stopping the internal combustion engine simultaneously with the failure of the pressure detection unit. Since it becomes possible, the same effect as the first aspect of the invention can be obtained.

The reference numerals in parentheses of the above means indicate the correspondence with the concrete means described in the embodiments described later.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing the structure of a pressure-accumulation type fuel injection device (hereinafter abbreviated as an injection device) 1 according to the present embodiment, and 2 is a diesel engine (hereinafter abbreviated as an engine). ). Reference numeral 3 denotes a low-pressure fuel pump (feed pump) for sucking the fuel in the fuel tank 4. Reference numeral 5 denotes a high-pressure fuel pump disposed near the engine 2 for pressurizing the fuel sent by the low-pressure fuel pump 3 to a predetermined pressure. It is a fuel pump.

Reference numeral 6 denotes a common rail (accumulator) for storing the fuel pressurized by the high-pressure fuel pump 5, and an injector (fuel injection valve) 8 is connected to the common rail 6 via a pipe 7 for each cylinder. It is arranged in. The common rail 6 is provided with a pressure sensor (pressure detecting means) 9 for detecting a pressure in the common rail 6, and an output signal (detected value) of the pressure sensor 9 is supplied to an electronic control unit (hereinafter referred to as an ECU). This is input to 10. Note that E
As is well known, the CU 10 is composed of a central processing unit (CPU), a read-only storage device (ROM) as storage means, and a storage device (RAM) that can be read and written as needed. Based on the signal, predetermined arithmetic processing is performed according to a program or the like stored in the ROM in advance, and the arithmetic result (output signal) is output to the high-pressure pump 5 and the like.

Reference numeral 11 denotes an electromagnetic valve for opening and closing a passage for communicating the inside of the common rail 6 with the low-pressure side (the fuel tank 4 side). The electromagnetic valve 11 closes the passage when not energized. ) Type. As shown in FIG. 2, the structure of the solenoid valve 11 is arranged in series (inline) with respect to a passage from a high-pressure inlet 11a opening toward the common rail 6 to a drain 11b communicating with the fuel tank 4 side. It is configured. The solenoid valve 11 functions as a means for detecting the pressure in the common rail 6 when the pressure sensor 9 is in an abnormal state, as described later.

Reference numeral 11c denotes a valve port 11d of the solenoid valve 11.
Is a spherical valve element (steel ball) that opens and closes the valve element 11c.
Is pressed in a direction to close the valve port 11d by a coil spring 11g via an armature (movable iron core) 11e made of a magnetic material and a spring holder 11f made of a non-magnetic material. Reference numeral 11h denotes an excitation coil (solenoid coil). Inside the solenoid coil 11h, a stopper (fixed iron core) 11j made of a magnetic material and having a passage 11i through which fuel passes together with a spring holder 11f is provided. ing. The gap 11k between the armature 11e and the stopper 11j when not energized is about 50 μm.

In FIG. 1, reference numeral 12 denotes current detecting means for detecting a current flowing through the solenoid valve 11 (solenoid coil 11h), and reference numeral 13 denotes a solenoid valve 11 (solenoid coil 1h).
1h) is a driving means for applying a predetermined voltage intermittently (pulse-wise) to drive the electromagnetic valve 11. Also, EC
U10 receives an output signal from a rotation sensor 14 for detecting the number of revolutions of the engine 2 and an output signal from an accelerator opening sensor 15 for detecting the opening of accelerator means operated by an occupant.

Next, the operation of the solenoid valve 11 will be described. When the electromagnetic valve 11 (solenoid coil 11h) is energized, an electromagnetic attraction force is generated between the armature 11e and the stopper 11j, and the armature 11e is attracted to the stopper 11j by overcoming the elastic force of the coil spring 11g. As a result, the valve element 11c loses the force to close the valve port 11d, so that the pressure in the common rail 6 causes the valve element 11c to move toward the stopper 11j and open the valve port 11d.

On the other hand, when the energization is cut off, the electromagnetic attraction force disappears, so that the elastic force of the coil spring 11g overcomes the pressure in the common rail 6 and presses the valve body 11c to close the valve port 11d. When the solenoid valve 11 (solenoid coil 11h) is energized, the current i actually flowing through the solenoid coil 11h rises later than the voltage V ₀ (V) applied to the solenoid coil 11h. This is because the reactance L of the solenoid coil 11h generates an electromotive force that suppresses a voltage rise of the solenoid coil 11h, and this phenomenon is generally expressed by the following Equation 1.

[0021]

I = V ₀ / R ・ (1−e ^{−t / T} ) R: electric resistance of the solenoid coil 11h T≡R / L In equation (1), the reactance L is constant. When the armature 11e is sucked, the gap 1
Since 1k is reduced, the reactance L (rate of change of magnetic flux Φ (dΦ / dt)) increases at the same time as the armature 11e is attracted (moves), and as shown in FIG. 3, when the armature 11e is attracted. The current i decreases (point a in FIG. 3).

The armature 11e and the stopper 11j
The electromagnetic attraction force _Fm is generally expressed by the following equation (2).

[0023]

F _m = 10 ⁷ / 8π · B ² · S ₁ B: magnetic flux density of the air gap 11k S ₁ : area of a part involved in suction of the armature 11e Further, the magnetic flux density B is a current flowing through the solenoid coil 11h. Since it is considered to be a function uniquely determined by i, the relationship between the electromagnetic attraction force _Fm and the current i is as shown in the graph of FIG. In addition, the graph of FIG. 4 is a test result by an actual machine.

As is apparent from the above description, if the current i ₁ at the time (instantaneous) when the armature 11e is sucked is found, the electromagnetic attraction at that time can be obtained from the graph of FIG. By the way, when considering the balance of the force acting on the valve element 11c when the valve port 11d is opened (momentary), the following equation is obtained.

[0025]

[Equation 3] {(π / 4 · d ² ) · P} + F _m = F _s d: diameter of valve port 11d P: pressure in common rail 6 F _s : elastic force of coil spring 11g in closed state the size of the elastic force F _s is a maximum pressure greater than the value in the cylinder engine 2 (combustion chamber), and at a pressure (in this embodiment to the extent that the engine 2 is not damaged, 150
(Approximately MPa).

Here, when the pressure P in the common rail 6 is obtained from Expression 3, Expression 4 is obtained.

[0027]

Equation 4] _{P = (F s -F m)} / (π / 4 · d 2) = (F s -F m) / S 2 (S 2 ≡π / 4 · d 2) In addition, the electromagnetic attractive force F _m is a function of the current i flowing through the solenoid coil 11h as described above (F _m ≡F
In consideration of (i)), Equation 5 is obtained.
The pressure P in the common rail 6 can be obtained (estimated) from the above.

[0028]

Equation 5] _{P = (F s -F (i} )) / S 2 In this connection, the pressure sensor 9, as shown in FIG. 5, since an output voltage substantially proportional to the pressure to be detected, the output voltage value , The pressure in the common rail 6 is detected (calculated).

Next, the operation of the injection device according to this embodiment will be described with reference to the flowchart of FIG. First, when the engine 2 is started after the ignition switch (not shown) is turned on, the output signals of the sensors 9, 14, and 15 are read (S100), and the signals shown in FIGS. The target common rail pressure P _ref and the actual common rail pressure P _c are determined from the accelerator opening and the engine speed according to the map shown (S110, S12).
0).

Next, the output signal (voltage) of the pressure sensor 9
Is a predetermined range (in this embodiment, FIG. 5
Is determined to be within the range of 1V to 4V (S140), and when the output signal (voltage) of the pressure sensor 9 is within the predetermined range, the pressure sensor 9 is in a normal state. it is regarded as determines whether the target common rail pressure P _ref is above the actual Komoreru pressure P _c (S15
0).

[0031] Then, when the target common rail pressure P _ref is above the actual Komoreru pressure P _c increases the fuel pumping quantity of the high-pressure fuel pump 5 (S160). On the other hand, when the target common rail pressure P _ref is smaller than the actual Komoreru pressure P _c stops the high-pressure fuel pump 5 (S17
At the same time, the solenoid valve 11 is opened (S180). When the output signal (voltage) of the pressure sensor 9 is out of the predetermined range, the pressure sensor 9 is considered to be in an abnormal state, and the pressure sensor 9 fails for the occupant, and the fuel injection device fails. It warns that the mode operation has been shifted (S19)
0). This warning is performed by a warning means 16 (see FIG. 1) such as a warning light or a buzzer provided on an instrument panel such as a speedometer.

Next, the solenoid valve 11 is driven (opened) for a short time (S200), and a current i flowing through the solenoid valve 11 (solenoid coil 11h) is detected (S21).
0), the actual comoraire pressure _Pc is estimated (S220).
Thereafter, by using the estimated actual Komoreru pressure P _c S1
50 to S180 are executed. Note that the time for driving (opening) the solenoid valve 11 for a very short time needs to be such that the pressure in the common rail 6 does not greatly change. In the present embodiment, it is about 0.05 to 0.08 seconds. .

Next, the features of this embodiment will be described. According to the present embodiment, even if the pressure sensor 9 is determined to be in an abnormal state, the solenoid valve 11 (the solenoid coil 1
Estimates the actual Komoreru pressure P _c from the current i flowing through 1h), it is possible to operate the engine 2 on the basis of the actual Komoreru pressure P _c that this estimation, the vehicle does not stop at the same time as the failure of the pressure sensor 9.

Therefore, when the occupant learns from the warning means 16 that the pressure sensor 9 has failed,
Since the vehicle can be brought into an automobile dealer, a repair shop, or the like by self-propelled operation, it is possible to prevent a traffic jam and the like from greatly affecting third parties. Further, in addition to the pressure sensor 9, the solenoid valve 11 (solenoid coil 1)
1h), it is also possible to detect the pressure in the common rail 6 from the current i flowing in the same. Therefore, compared to an injection device that detects the pressure in the common rail 6 only with the pressure sensor 9,
The reliability of the injection device can be improved.

In the above embodiment, when it is determined that the pressure sensor 9 is in an abnormal state, the solenoid valve 1 is turned off.
1 using the actual Komoreru pressure P _c which is estimated from the current i flowing through the (solenoid coil 11h), the same control as when the pressure sensor 9 is normal state (S150～S18
0) was executed, but the following may be performed instead.

That is, when it is determined that the pressure sensor 9 is in an abnormal state, in S150, the pressure in the common rail 6 is replaced by the pressure in the common rail 6 instead of the target common rail pressure _Pref determined from the engine speed and the accelerator opening. and the operation (running) is causing the minimum necessary for abnormal operation when the common rail pressure P _ir (e.g. 18 MPa), compared with the actual Komoreru pressure P _c which is estimated from the current i, the high-pressure fuel pump 5 from the result obtained by the comparison To control.

In the above embodiment, the target common level
Pressure P_refIs the actual Comolair pressure P_cIs less than
, The high-pressure pump 5 is stopped and the electromagnetic valve 11
, But only to stop the high-pressure pump 5
Therefore, the actual comoraire pressure P _cIs the target common rail pressure
P_refThe control step for determining whether or not the
When provided between 170 and S180, this provided
By controlling the solenoid valve 11 based on the determination value of the determination step
Is also good.

Specifically, it is necessary to stop the high-pressure pump 5.
And the actual comoraire pressure P_cIs the target common record
Pressure P_refWhen it drops to below, close solenoid valve 1
Leave (do not drive), on the other hand, actual comoraire pressure P
_cIs the target common rail pressure P _refWhen it does not drop to
Opens the solenoid valve 11 to reduce the pressure in the common rail 6.
The pressure is quickly reduced.

In the above-described embodiment, the actual common rail pressure _Pc is estimated by detecting the current i flowing through the solenoid valve 11, but the actual common rail pressure _Pc is estimated from the current flowing through the solenoid coil (not shown) of the injector 8. P _c may be estimated. In the above-described embodiment, whether the pressure sensor 9 is in a normal state is determined based on whether the output voltage of the pressure sensor 9 is within a predetermined range. That is, before S140, S200 to
220 is executed, and the estimated actual comoraire pressure P
_c and the actual comoraire pressure P detected by the pressure sensor 9
_When the deviation of the detected value exceeds a predetermined range, it is determined that the pressure sensor is in an abnormal state, and when the deviation is within a predetermined range, the pressure sensor is in a normal state. May be determined.

In the above-described embodiment, the voltage is applied to the electromagnetic valve 11 in a rectangular waveform. However, the present invention is not limited to the method for driving the electromagnetic valve 11, and the current detecting means 12 The present invention can be implemented by intermittently applying a voltage to such an extent that a change in the current i accompanying the operation of the armature 11e can be detected. In the above-described embodiment, the pressure sensor 9 and the solenoid valve 11 are connected to the common rail 6.
Although the present invention is not limited to this, the present invention is not limited to this, as long as it is a part that communicates with the common rail 6 (a part that is statically equal to the pressure in the common rail 6), the other part such as the pipe 7 It may be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a pressure accumulating fuel injection device.

FIG. 2 is a sectional view of a solenoid valve.

FIG. 3 is a graph showing a current flowing through an electromagnetic valve (solenoid coil) and an applied voltage.

FIG. 4 is a graph showing a relationship between an electromagnetic attraction force acting on an armature and a current flowing through an electromagnetic valve (solenoid coil).

FIG. 5 is a graph showing a relationship between an output voltage of a pressure sensor and pressure.

FIG. 6 is a flowchart showing the operation of the accumulator type fuel injection device.

FIG. 7 is a map showing a relationship between an accelerator opening, an engine speed, and a target common rail pressure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Accumulation type fuel injection device, 2 ... Engine, 3 ... Low pressure fuel pump, 4 ... Fuel tank, 5 ... High pressure fuel pump, 6 ... Accumulation container (common rail), 7 ... Fuel injection valve (injector), 8 ... Piping, 9 ... pressure sensor (pressure detecting means), 1
0: electronic control unit (ECU), 11: solenoid valve, 12: current detecting means, 13: driving means.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 37/00 F02M 37/00 C 37/08 37/08 B // F02M 47/02 47/02

Claims (5)

[Claims] An accumulator (6) for storing a fuel pressurized to a high pressure.
A fuel pump (5) for pumping fuel into the pressure accumulator (6); and a fuel pump (5) for pumping the fuel into the pressure accumulator (6). Pressure detecting means (9) for detecting pressure; determining means (S140) for determining whether the pressure detecting means (9) is in a normal state; and the pressure detecting means (9) by the determining means (S140). ) Is determined to be in a normal state, the pressure storage container (6) based on the detection value of the pressure detecting means (9).
First control means (S150 to S170) for operating the fuel pump (9) so that the internal pressure becomes a predetermined value; and if the pressure detection means (9) is in an abnormal state by the determination means (S140). When it is determined, the second control means (S150 to S17) for operating the fuel pump (5) based on a predetermined program set in advance.
0, S190 to S220). 2. A pressure accumulator (6) for storing fuel pressurized to a high pressure.
A fuel pump (5) for pumping fuel into the pressure accumulator (6); and a fuel pump (5) for pumping the fuel into the pressure accumulator (6). A pressure detecting means (9) for detecting pressure; a determining means (S140) for determining whether or not the pressure detecting means (9) is in a normal state; and a passage communicating between the inside and the outside of the pressure accumulating vessel (6). An electromagnetic valve (11) that opens and closes; a driving unit (13) that intermittently applies a voltage to the electromagnetic valve (11) to drive a movable part (11e) in the electromagnetic valve (11); Current detecting means (12) for detecting a current flowing through the solenoid valve (11); and storage means (storing means) storing an electromagnetic attraction force acting on the movable portion (11e) in correspondence with the current flowing through the solenoid valve (11). ROM) and the determination means (S140) When serial pressure detecting means (9) is determined to be a normal state, on the basis of the detected value of said pressure detecting means (9) pressure accumulator (6)
The first control means (S150 to S170) for operating the fuel pump (5) so that the internal pressure becomes a predetermined value, and the pressure detection means (9) is in an abnormal state by the determination means (S140). When the determination is made, the electromagnetic valve (11) is driven by the driving means (13),
The pressure in the pressure accumulator (6) is estimated based on the value detected by the current detecting means (12) and the value stored in the storage means (ROM). Second control means (S150 to S170, S190 to S22) for operating the fuel pump (5) so as to have a value.
0). 3. The accumulator type fuel injection device according to claim 2, wherein the solenoid valve (11) communicates the inside of the accumulator vessel (6) with a suction side of the fuel pump (5). 4. The pressure detecting means (9) determines that the pressure detecting means (9) is in an abnormal state when the detection value of the pressure detecting means (9) is out of a predetermined range set in advance. The accumulator type fuel injection device according to any one of claims 1 to 3, wherein it is determined that there is a fuel injection device. 5. An accumulator (6) for storing fuel pressurized to a high pressure.
A pressure-accumulation type fuel injection device that receives the fuel into each cylinder of the internal combustion engine, and opens and closes a passage communicating between the inside and outside of the pressure accumulation container (6); A driving means (13) for intermittently applying a voltage to (11) to drive a movable portion (11e) in the electromagnetic valve (11); An accumulator comprising: a detection means (12); and a storage means (ROM) storing an electromagnetic attraction force acting on the movable portion (11e) in accordance with a current flowing through the electromagnetic valve (11). Fuel injection device.