JPH10176587A - High pressure fuel supply device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply fuel such that a vehicle can be reliably operated in a reserved state by judging abnormalities in the feedback control system of a high pressure pump. SOLUTION: Fuel pressurized to a high pressure in the pressurizing room 2 of a high pressure pump 11 is supplied to an engine 1 and the fuel pressure is controlled by a spill valve 41. The fuel pressure detected by a fuel pressure sensor 61 is compared with a target value determined according to the operating state of an engine and is controlled by feedback so as to reduce a pressure difference between them to zero and is brought near to a target fuel pressure. If an ECU 60 judges that there is an abnormality in a feedback control system under a feedback control like this, the spill valve 41 is forcibly controlled before feedback control means to supply the fuel at the fuel pressure where a vehicle can be operated in a reserved state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for supplying high-pressure fuel from a high-pressure pump to an internal combustion engine. More specifically, the present invention diagnoses the occurrence of an abnormality in a feedback control system of a high-pressure pump. The present invention relates to a high-pressure fuel supply device for an internal combustion engine that supplies fuel so as to perform a limp-home operation.

[0002]

2. Description of the Related Art An apparatus for supplying high-pressure fuel to an internal combustion engine generally includes a high-pressure pump for pressurizing fuel to be supplied to the engine. For example, such an apparatus includes an abnormality warning device that warns when an abnormality occurs in a high-pressure pump as described in Japanese Utility Model Laid-Open No. 5-69374.

FIG. 6 shows an example of the configuration of the above-mentioned abnormality warning device.
As shown in FIG. 1, the device 100 includes a low-pressure fuel pump 101 and a high-pressure pump 102. A passage 105 from the fuel tank 103 is connected to the low-pressure fuel pump 101. Discharge side passage 10 of low pressure fuel pump 101
Numeral 6 is connected to the low-pressure regulator 104 via the filter 107, and further from the low-pressure regulator 104 to the fuel tank 103. The low-pressure fuel having a substantially constant pressure is pumped and supplied to the high-pressure pump 102 by the low-pressure pump system having such a configuration.

The high-pressure pump 102 has a low-pressure regulator 1
The passage 108 from the terminal 04 is connected. High pressure pump 1
02 is connected to a common rail 111 via a filter 110. Common rail 11
A high-pressure regulator 115 is provided in the middle of a passage 113 returning from 1 to the fuel tank 103.

The common rail 111 has a bank rail 1
18 and an accumulator 116 are connected. An injector 117 is mounted on the bank rail 118. In such a high-pressure pump system, the high-pressure fuel from the high-pressure pump 102 is supplied to the injector 117 of the bank rail 118 via the common rail 111 by pumping the high-pressure fuel to the internal combustion engine. The control unit 120 includes a fuel pressure sensor 121 disposed on the common rail 111.
Is connected. Also, the ignition switch 122
And various sensors 123 are connected.

In such a configuration, a control unit 120 for controlling the abnormality warning device 100 as shown in FIG.
Feeds back a control current based on the detection values detected by the fuel pressure sensor 121, the accelerator opening sensor 124, and the engine speed sensor 125, and performs feedback control so that the control fuel pressure by the high-pressure regulator 115 matches the target fuel pressure. If the feedback correction value based on the detected value exceeds a predetermined range, it is determined that an abnormality has occurred in the high-pressure pump 102 and the fact is indicated by the abnormality display means 1.
26.

[0007]

The above-mentioned abnormality warning device 1
At 00, it is possible to notify that an abnormality has occurred in the high-pressure pump 102. However, in reality, even if an abnormality occurs, it is not possible to stop the vehicle immediately, and it is necessary to be able to perform evacuation and drive to a repair shop such as a dealer.
For this reason, it is necessary to control the fuel pressure of the high-pressure pump in order to properly perform the evacuation operation even under abnormal conditions, but such a conventional device cannot perform such evacuation operation control.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to diagnose, when an abnormality occurs in a feedback control system of a high-pressure pump in a high-pressure fuel supply device of an internal combustion engine, the abnormality. And to supply the fuel so that the evacuation operation can be surely performed.

[0009]

To achieve the above object, the present invention provides a high-pressure pump which pressurizes fuel transferred from a fuel tank in a pressurizing chamber and directly supplies the fuel to an internal combustion engine. A discharge control valve that controls the fuel pressure by changing the energization timing for opening and closing the valve with respect to the pressurization timing in the pressurization chamber, a fuel pressure sensor that detects the actual fuel pressure of the high-pressure pump, A feedback control means for feedback-controlling the energization timing to the discharge control valve so that the actual fuel pressure matches a target fuel pressure according to the engine operating state, wherein the feedback control system has an abnormality. Diagnostic means for diagnosing the abnormality, and forcible control means for forcibly controlling the discharge control valve by stopping the feedback control when the diagnostic means determines that there is an abnormality. The door to the spirit of the invention.

According to the first aspect of the present invention, fuel pressurized to a high pressure in the pressurizing chamber of the high-pressure pump is supplied to the internal combustion engine, and the fuel pressure is controlled by the discharge control valve.
The fuel pressure detected by the fuel pressure sensor is compared with a target fuel pressure determined according to the engine operating state, and feedback control is performed so that the pressure difference becomes “0”, and the fuel pressure approaches the target fuel pressure. Under such feedback control, the diagnosing means diagnoses an abnormality of the feedback control system, and the forcible control means controls the abnormality prior to the feedback control means. That is, the feedback control is stopped, and the fuel pressure is set to a pressure at which the vehicle can be operated in the evacuation mode controlled by the forcible control means.

The invention described in claim 2 is the first invention.
In the high-pressure fuel supply device for an internal combustion engine, the diagnostic means diagnoses whether or not at least one of the discharge control valve and the fuel pressure sensor is abnormal. When configured as in the invention of claim 2, in addition to the operation of the invention of claim 1, an abnormality is diagnosed in the discharge control valve and / or the fuel pressure sensor of the feedback control system. That is, an efficient fail-safe is realized based on the diagnosis of the minimum necessary elements of the feedback control system.

Further, the invention described in claim 3 is the first invention.
In the high-pressure fuel supply device for an internal combustion engine, the diagnosing means diagnoses the presence or absence of an abnormality in the fuel pressure detection sensor and the discharge control valve, and the forcible control means determines that the diagnostic means has an abnormality in the sensor. When the diagnosis is made, the discharge control valve is forcibly controlled so that the fuel pressure of the high-pressure pump becomes the highest. When the diagnostic means diagnoses that the discharge control valve is abnormal, the discharge is performed so that the fuel pressure of the high-pressure pump becomes the lowest. The purpose is to forcibly control the control valve.

According to the third aspect of the invention, in addition to the function of the first aspect of the invention, the diagnostic means determines that an abnormality such as a malfunction has occurred in one of the fuel pressure sensor and the discharge control valve. For example, if it is diagnosed that the abnormality has occurred in the fuel pressure sensor, the compulsory control means controls the energization of the discharge control valve so that the fuel pressure of the high-pressure pump becomes maximum. Then, the fuel pressurized to the maximum by the high-pressure pump is supplied to the internal combustion engine. On the other hand, if it is diagnosed that the abnormality has occurred in the discharge control valve, the forcible control means controls the energization of the discharge control valve so that the pressure discharged from the high-pressure pump becomes minimum. Then, the fuel with the lowest fuel pressure is supplied to the internal combustion engine.
In any case, the vehicle can be evacuated by forced control of the discharge control valve according to the content of the abnormality.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a fuel supply device for a gasoline engine for a vehicle will be described below.

FIG. 1 shows a schematic configuration of a fuel supply device 10 according to the present embodiment. This fuel supply device 10
Is a high pressure pump 11, a spill valve 41, a fuel tank 13,
And a low-pressure feed pump 14 and the like. The high-pressure pump 11 pressurizes the fuel to a high pressure. The high-pressure pump 11 is formed by a cylinder 20, a plunger 21 reciprocating in the cylinder 20, and an inner wall surface of the cylinder 20 and an upper end surface of the plunger 21. A pressure chamber 22 is provided.

A tappet 23 attached to the lower end (lower end in the figure) of the plunger 21 is pressed against a cam 25 provided on a crankshaft 24 of the engine E by the urging force of a spring (not shown). Crankshaft 2
As the cam 25 rotates with the rotation of 4, the plunger 21 reciprocates in the cylinder 20 and the volume in the pressurizing chamber 22 changes.

The pressurizing chamber 22 is connected to the fuel tank 13 by an inflow passage 30. The low-pressure feed pump 14 is provided in the inflow passage 30.
Accordingly, the fuel in the fuel tank 13 is sucked and discharged. In the present embodiment, the discharge pressure of the pump 14 is set to 0.3 megapascal (MPA). The discharged fuel flows through the inflow passage 30 and is introduced into the pressurizing chamber 22 when the plunger 21 moves down in the cylinder 20. Further, an inflow passage 30 between the low-pressure feed pump 14 and the pressurizing chamber 22 is provided.
Is provided with a check valve 31. The check valve 31 allows only the flow of fuel from the low-pressure feed pump 14 to the pressurizing chamber 22 in the inflow passage 30.

A portion of the inflow passage 30 between the low-pressure feed pump 14 and the check valve 31 (hereinafter, this portion is referred to as a “discharge-side inflow passage 32”) is connected to the fuel tank 13 by a relief passage 33. A relief valve 34 is provided in the middle of the relief passage 33. The relief valve 34 opens when the fuel pressure in the discharge-side inflow passage 32 becomes higher than a predetermined value. By opening the relief valve 34, the fuel in the discharge-side inflow passage 32 is returned to the fuel tank 13 through the relief passage 33. As a result, the pressure of the fuel transferred from the low-pressure feed pump 14 to the pressurizing chamber 22 is maintained substantially constant.

The pressurizing chamber 22 is connected by a supply passage 35 to a common rail 55 provided in the engine E.
The common rail 55 is for maintaining the fuel at a high pressure and distributing the fuel to an injector 56 described later.

The engine E is provided with a plurality of injectors 56 corresponding to each cylinder. Each injector 56 is connected to a common rail 55, respectively.
The high-pressure fuel in the rail 55 is distributed and supplied to the injector 56. The supply passage 35 is provided with a check valve 36 that allows only the flow of fuel from the pressurizing chamber 22 toward the common rail 55, and the valve 36 allows the reverse flow of fuel from the common rail 55 to the pressurizing chamber 22. Regulated.

The common rail 55 is connected to the fuel tank 13 by a relief passage 38 provided with a relief valve 37 in the middle. When the fuel pressure of the common rail 55 rises to a predetermined value or higher, the relief valve 34 is opened, and the fuel in the common rail 55 is returned to the fuel tank 13 through the relief passage 38. This allows
Excessive fuel pressure in the common rail 55 is prevented. In the present embodiment, the predetermined value at which the relief valve 37 is opened is 140 megapascals (MPA).

The injector 56 opens and closes based on a signal from an electronic control unit (hereinafter, referred to as “ECU”) 60 of the engine E to inject and supply a predetermined amount of fuel to each cylinder of the engine E. A fuel pressure sensor 61 is attached to the common rail 55. Fuel pressure sensor 61 detects fuel pressure Pf in common rail 55 and outputs a signal corresponding to the pressure to ECU 60. Engine E
Is provided with a rotational speed sensor 62. The rotation speed sensor 62 detects the rotation speed of a crankshaft (not shown) of the engine E, that is, the rotation speed NE of the engine E, and outputs a signal corresponding to the rotation speed to the ECU 60. An accelerator sensor 64 is attached to the accelerator pedal 63. The accelerator sensor 64 detects the depression amount ACC of the accelerator pedal 63 and outputs a signal corresponding to the depression amount to the ECU 60.

The pressurizing chamber 22 is connected to the fuel tank 13 by a spill passage 39 whose portion connected to the same chamber 22 is common to the supply passage 35. In the middle of the spill passage 39, a spill valve 4 serving as a discharge control valve of the high-pressure pump 11 is provided.
1 is provided. The spill valve 41 is a normally-open electromagnetic valve, and is controlled to be energized by the ECU 60. In the spill passage 39 downstream of the spill valve 41,
A pressure regulating valve 40 is provided which regulates the backflow of fuel from the fuel tank 13 to the spill valve 41 and opens when the fuel pressure in the passage becomes equal to or higher than a predetermined pressure.

FIG. 2 shows a cross section of the spill valve 41 (FIG. 1 schematically shows the structure of the spill valve 41). As shown in FIG. 2, the housing 42 of the spill valve 41 is fixed to the pump body 12 of the high-pressure pump 11. A substantially cylindrical sleeve 43 is provided in the housing 42.
, And a stator 44 is fixed to the sleeve 43.

In the housing 42, an annular solenoid coil 45 is provided so as to cover the outer periphery of the stator 44. Solenoid coil 45 is lead wire 45a
Is connected to the ECU 60 via the. The stator 44 is excited when the solenoid coil 45 is energized by the ECU 60.

A guide 46 having a cylindrical shape is inserted into and supported by the distal end portion of the housing 42 (the left side portion in FIG. 2). Inside the guide 46, a through hole 46a having an enlarged diameter at the distal end side is formed, and a substantially cylindrical valve shaft 47 is movably inserted and supported in the through hole 46a. The distal end portion of the valve shaft 47 is enlarged in diameter, and the enlarged diameter portion constitutes a valve body 47a. Through hole 4
The peripheral portion of the distal opening 6a corresponds to the valve seat 46b of the spill valve 41. The valve body 47a comes into contact with and separates from the valve seat 46b as the valve shaft 47 reciprocates. Further, an annular internal spill space 48 is defined by the inner peripheral surface on the distal end side of the through hole 46 a and the outer peripheral surface of the valve shaft 47.

A substantially disk-shaped armature 53 is integrally formed at a base end portion (right end portion in FIG. 2) of the valve shaft 47. The armature 53 is movably supported by the housing 42 and the sleeve 43, and its base end face is
Are arranged to face each other so as to be close to the front end surface of the first member. Also,
An insertion hole 44a is formed in a tip portion of the stator 44,
A spring 49 is inserted and supported in the insertion hole 44a. The armature 53 is urged by the spring 49 in a direction in which the valve body 47a is separated from the valve seat 46b.

When the stator 44 is not excited in the spill valve 41, the valve body 47a is separated from the valve seat 46b by the urging force of the spring 49.
Is always open. On the other hand, when the stator 44 is excited by the solenoid coil 45, the armature 53 is attracted to the stator 44. As a result, the armature 5 resists the urging force of the spring 49.
3 moves to the stator 44 side, and this movement causes the valve body 47 to move.
a is seated on the valve seat 46b, and the spill valve 41 is closed.

An introduction space 50 is formed in the pump body 12 at a portion facing the distal end surface of the valve body 47a. The introduction space 50 is formed by the spill passage 39 in the pressurizing chamber 2.
The fuel pressurized in the pressurizing chamber 22 is introduced to the fuel cell 2.

An annular outer spill space 51 is defined by the inner peripheral surface of the pump body 12, the outer peripheral surface of the guide 46, and the distal end surface of the housing 42. The external spill space 51 and the internal spill space 48 communicate with each other by a spill hole 52 formed in the guide 46. Furthermore,
The external spill space 51 is connected to the fuel tank 13 through the spill passage 39 via the pressure regulating valve 40.

The spill hole 52 communicates with a gap 54 formed between the base end face of the armature 53 and the tip end face of the stator 44 by passages 46c and 53a formed in the guide 46 and the armature 53. .

Next, a fuel pressure feedback control process of the high pressure pump 11 of the fuel supply device 10 will be described with reference to FIG. The ECU 60 periodically repeats this routine when the engine E is driven.

In step S101, the ECU 60 reads the engine speed NE and the depression amount ACC detected by the rotation speed sensor 62 and the accelerator sensor 64 as input values. Also, in step S102, the fuel pressure sensor 61
Is read as an input value. Next, in step S103, the target fuel pressure PfT is calculated based on the input values of the engine speed NE and the depression amount ACC, and in step S104, it is determined whether the target fuel pressure PfT is higher than the actual fuel pressure Pf.

If the target fuel pressure PfT is higher than the actual fuel pressure Pf, the ECU 60 controls the spill valve 41 in a direction to increase the fuel pressure in step S105. On the other hand, the actual fuel pressure P
If it is determined that the target fuel pressure PfT is not higher than f, the target fuel pressure Pf is higher than the actual fuel pressure Pf in step S106.
It is determined whether T is small. If the target fuel pressure PfT is smaller than the actual fuel pressure Pf, E is determined in step S107.
The CU 60 controls the spill valve 41 to lower the fuel pressure. Here, if the target fuel pressure PfT is not smaller than the actual fuel pressure Pf, the process proceeds to step S108. When the processing in steps S105 and S107 is completed, the process also proceeds to step S108. Step S108
It is determined whether or not the actual fuel pressure Pf and the target fuel pressure PfT are the same, and if not, the process proceeds to step S104. On the other hand, when the actual fuel pressure Pf and the target fuel pressure PfT are the same, the routine is temporarily terminated, assuming that the target value has been converged.

Next, the operation of the fuel supply device 10 configured as described above will be described. When the operation of the engine E is started, the cam 25 rotates with the rotation of the crankshaft 24. The plunger 21 is reciprocated vertically in the cylinder 20 by the rotating cam 25.
Then, the fuel in the fuel tank 13 that is pressure-fed into the inflow passage 30 from the low-pressure feed pump 14 is
Starts moving downward from the top dead center, and at the same time, is introduced into the pressurizing chamber 22 via the check valve 31. At this time, the solenoid coil 45 of the spill valve 41 is not energized by the ECU 60, and the spill valve 41 is open. As described above, in the present embodiment, the fuel is introduced into the pressurizing chamber 22 through the inflow passage 30 provided separately from the spill passage 39. Therefore, the introduction of fuel is not hindered by the valve element 47a of the spill valve 41, and the plunger 21 always moves downward from the top dead center to the bottom dead center regardless of the open / closed state of the valve 41. Fuel is introduced into the pressurizing chamber 22. For this reason, according to this embodiment, sufficient fuel can be reliably introduced into the pressurizing chamber 22.

Next, the plunger 21 starts to move upward from the bottom dead center. At this time, when the spill valve 41 is open, the fuel in the pressurizing chamber 22 overflows into the spill passage 39 and returns to the fuel tank 13. Therefore, the fuel is not pressurized, and the fuel is not pumped into the common rail 55. On the other hand, when the spill valve 41 is closed, the fuel in the pressurizing chamber 22 is pressurized. Then, the pressurized fuel is pressure-fed to the common rail 55 through the supply passage 35 with the opening of the check valve 36. In the fuel supply device 10 according to the present embodiment, the fuel pumping amount is adjusted by adjusting the timing at which the ECU 60 closes the spill valve 41, that is, the timing at which energization of the solenoid coil 45 is started.
Then, the ECU 60 performs feedback control on driving of the spill valve 41 through the routine shown in FIG. 3 so that the fuel pressure in the common rail 55 detected by the fuel pressure sensor 61 becomes a predetermined pressure.

FIGS. 4A to 4C show the plunger 21.
The relationship between the vertical movement of the spill valve 41 and the closing timing of the spill valve 41 is shown. The opening and closing amount of the spill valve 41 is determined by the vertical movement of the plunger 21 (ON
OFF) The duty is controlled for the cycle.
As shown in FIG. 4A, when the closing timing of the spill valve 41, that is, the energization start timing I to the solenoid coil 45 is performed simultaneously with the upward movement start timing θ of the plunger 21, the duty ratio is 100%. Is maximum (about 160 megapascals (MPA)). FIG.
FIG. 4B shows a case where the closing time of the spill valve 41 is half that of FIG. 4A (the duty ratio is 50%). The energization to the solenoid coil 45 is started at a timing I delayed by a predetermined time α from the upward movement of the plunger 21.

On the other hand, when no current is supplied to the solenoid coil 45 as shown in FIG.
%, There is no pressurization by the high pressure pump 11 and only the pressure of the low pressure feed pump 14 (0.3 MPa) is supplied to the common rail 55.

Next, diagnosis processing and fail-safe control when an abnormality occurs in the fuel pressure sensor 61 or the solenoid coil 45 will be described with reference to FIG. Here, before the abnormality occurs, the engine E is in a stratified combustion state,
It is assumed that the injection of high-pressure fuel from the injector 56 into the cylinder (not shown) of the engine E is controlled. The ECU 60 periodically repeats this routine when the engine E is driven.

In step S201, the ECU 60 determines (diagnoses) whether the fuel pressure sensor 61 has an abnormality. The abnormality means that no detection signal is output due to disconnection between the fuel pressure sensor 61 and the ECU 60,
It is assumed that the detection signal is constantly output due to a short circuit. When it is determined that the fuel pressure sensor 61 is abnormal, first, in step S202, a warning lamp is turned on to notify the driver of the abnormality, and an abnormality code is output to the backup ROM to record the history of the abnormality thereafter. Remember. Then, in step S203, the ECU 60 calculates the duty ratio of the spill valve 41 from the valve closing timing, that is, the start timing I (see FIG. 4) of energizing the solenoid coil 45.

Next, in step S204, it is determined whether the calculated duty ratio has reached 100%. If the duty ratio is less than 100%, the energization start timing I is later than the upward movement start timing θ (for example, as shown in FIG. 4B), and in Step S205, a predetermined smoothing value ( The process proceeds to step S203.
Step S203 until the duty ratio reaches 100%
In step S205, the smoothing control (gradual change control) is repeated. Steps S203 to S205 constitute a smoothing control means (gradual change control means).

On the other hand, when the duty ratio reaches 100%, the duty ratio is maintained in step S206. As a result, the maximum discharge pressure from the high-pressure pump 11 is supplied to the common rail 55. At this time, since the relief valve 37 of the common rail 55 is opened, the fuel pressure in the common rail 55 is maintained at a predetermined pressure (about 140 megapascals (MPA)).
Then, in step S207, the injection of the injector 56 is controlled, and the engine E which has been in the stratified combustion state is brought into the stoichiometric operation state.

If there is no abnormality in the fuel pressure sensor 61 in step S201, the ECU 60 determines in step S208 whether or not there is an abnormality in the solenoid coil 45. The abnormality means, for example, that the solenoid coil 45
It is assumed that the solenoid coil 45 stops functioning due to a disconnection between the ECU 60 and the ECU 60, or a case where a short circuit occurs and the power is always supplied. And the solenoid coil 4
If it is determined that there is an abnormality in Step S5, Step S20
In step 9, the warning lamp is turned on to notify the driver of the abnormality, and the abnormality code is output to the backup ROM to store the history of the subsequent abnormality. Then, in step S210, the ECU 60 sets the solenoid coil 45
Stop supplying power to That is, as shown in FIG. 4C, the spill valve 41 is kept open, and the pressure (0.3) of the low-pressure feed pump 14 which is not pressurized by the high-pressure pump 11 is used.
Only megapascals (MPAs) are supplied to the common rail 55. Then, in step S211, the injector 5
The engine E which has been in the stratified combustion state by the injection control of the engine 6 is brought into the stoichiometric operation state.

Here, when it is determined that there is no abnormality in the solenoid coil 45, it is determined in step S212 whether there is a system abnormality. Here, the system abnormality is, for example, a case where the fuel pressure does not increase even though there is no abnormality in the fuel pressure sensor 61 and the solenoid coil 45 in the above step, and the supply passage 35 is clogged or dropped from the disposition position. Is assumed. If there is a system abnormality, a warning lamp is turned on in step S213 to notify the driver of the abnormality, and an abnormality code is output to a backup ROM to store the history of the subsequent abnormality. Then, in step S214, the fuel supply is gradually restricted to stop the engine E.

With the above configuration, the present embodiment has the following effects. (1) When the fuel pressure sensor 61 is abnormal, the operation is performed with the duty ratio of the solenoid coil 45 fixed at 100% forcibly ignoring the detection value of the fuel pressure sensor 61. Therefore, the evacuation operation can be performed without being affected by the fuel pressure sensor 61. Further, if there is an abnormality in the solenoid coil 45, the energization to the solenoid coil 45 is forcibly cut (duty ratio 0%), so that the evacuation operation can be performed without being affected by the abnormality in the solenoid coil 45. it can.

(2) When an abnormality is detected in the fuel pressure sensor 61 or the solenoid coil 45 in the stratified combustion state, the operation is performed with the duty ratio of the solenoid coil 45 fixed at 100% or 0%. At that time, since the state is returned from the stratified combustion state to the stoichiometric state, the combustion is stabilized, and the risk of misfiring or the like is reduced.

(3) If the fuel pressure sensor 61 is abnormal, the duty ratio of the solenoid coil 45 is immediately changed to 10
Instead of being fixed at 0%, the duty ratio is controlled so as to gradually reach 100% by smoothing control. Therefore, abrupt behavior of the engine is prevented, and as a result, the fuel pressure sensor 61
No shock occurs when shifting to the evacuation operation based on the abnormality.

(4) When the operation is performed with the duty ratio of the solenoid coil 45 fixed at 100% when the fuel pressure sensor 61 is abnormal, the high-pressure pump 11 supplies the fuel to the common rail 55 at the maximum discharge pressure. In this case, the fuel pressure in the common rail 55 is maintained at a constant value by the relief valve 37 attached to the common rail 55 even if a slight change in the discharge pressure occurs.

(5) When there is no abnormality in both the fuel pressure sensor 61 and the solenoid coil 45 and it is determined that the system is abnormal, for example, if the supply passage 35 is clogged and the fuel supply becomes insufficient, it takes a long time. Evacuation operation may not be possible. Therefore, when it is determined that the system is abnormal, the driver is notified of the fact and the engine is gradually stopped.

Although one embodiment has been described above, the present invention can be modified and implemented in another embodiment as follows. (1) In the above embodiment, when the fuel pressure sensor 61 is abnormal, the operation is performed with the duty ratio of the solenoid coil 45 fixed at 100%. But not necessarily 1
The duty ratio does not need to be 00%, and may be fixed at another duty ratio.

(2) In the above embodiments, the present invention is embodied as a high-pressure fuel supply device 10 for a vehicle gasoline engine E. However, the present invention can be applied to a diesel engine, for example. However, the present invention is not limited to vehicles, and can be applied to stationary power engines.

(3) In each of the above embodiments, the spill valve 41
Although a normally-open solenoid valve is used as the above, a normally-closed solenoid valve may be employed. (4) In the above embodiment, if an abnormality occurs in the fuel pressure sensor 61, the duty ratio of the solenoid coil 45 to the duty ratio 100
%, And smoothing control is performed until the current reaches 100% to prevent abrupt engine behavior. However, the smoothing control need not always be performed. It is to be noted that the embodiment can be freely changed and implemented.

The technical ideas that can be grasped from the above embodiments are described below together with their effects. (A) In the high-pressure fuel supply system for an internal combustion engine according to claim 1, the diagnostic means diagnoses whether or not the discharge control valve is abnormal. If it is diagnosed that there is an abnormality, it is intended that the discharge control valve be energized so that the fuel pressure of the high-pressure pump becomes minimum.

With this configuration, when the diagnosis means diagnoses that an abnormality such as an operation failure has occurred in the discharge control valve, the forcible control means controls the energization of the discharge control valve so that the fuel pressure of the high-pressure pump is minimized. I do. Then, the fuel of the lowest pressure is supplied to the internal combustion engine.

(B) In the high-pressure fuel supply device for an internal combustion engine according to claim 1, the diagnostic means diagnoses whether or not the fuel pressure sensor is abnormal. If the sensor is diagnosed as having an abnormality, the purpose is to energize the discharge control valve so that the fuel pressure of the high-pressure pump becomes the highest.

With this configuration, when the diagnosis unit diagnoses that the fuel pressure sensor has an abnormality such as an operation failure, the compulsory control unit controls the energization of the discharge control valve so as to minimize the fuel pressure of the high-pressure pump. . Then, the fuel with the highest pressure is supplied to the internal combustion engine.

(C) In the high-pressure fuel supply system for an internal combustion engine according to claim 3, when it is diagnosed that the discharge control valve is abnormal, energization of the discharge control valve is stopped to forcibly control the fuel pressure to a minimum. A high-pressure fuel supply device for an internal combustion engine.

(D) In the high-pressure fuel supply device for an internal combustion engine according to the first aspect, when the diagnosis means diagnoses that there is an abnormality in the feedback system although it has determined that no abnormality has occurred in the feedback system. Is characterized in that the fuel supply is stopped. With this configuration, if there is any abnormality in the system, the driving of the engine itself can be stopped.

(E) If the diagnostic means diagnoses that the sensor is abnormal, the forcible control means controls the discharge control valve gradually so that the fuel pressure gradually becomes the maximum pressure. High pressure fuel supply system for an internal combustion engine as described. With this configuration, a sudden behavior can be prevented.

(F) In the high-pressure fuel supply device for an internal combustion engine according to the first aspect, when the diagnosis means determines that an abnormality has occurred in the feedback control system, the forcible control means controls the energization of the discharge control valve. When the combustion condition of the internal combustion engine is in a stratified combustion state, the state is returned to a stoichiometric state. With this configuration, it is possible to stabilize combustion during the evacuation operation.

(G) In the high-pressure fuel supply device for an internal combustion engine according to (f), the diagnosis means diagnoses the presence or absence of abnormality in at least one of the discharge control valve and the fuel pressure sensor. With this configuration, it is possible to stabilize combustion during the evacuation operation.

(H) In the high pressure fuel supply system for an internal combustion engine according to claim 3 or (b), the maximum fuel pressure discharged from the high pressure pump is controlled to a predetermined pressure on the way to the cylinder of the internal combustion engine. It is characterized by having a pressure control means (relief valve 37 in the above embodiment). With this configuration, fuel can be supplied to the cylinder of the internal combustion engine at a stable fuel pressure.

[0063]

According to the first aspect of the present invention, when an abnormality occurs in devices involved in the feedback control, it is possible to reliably perform the limp-home run despite the abnormality of the devices. In the invention described in claim 2, in addition to the effect of the invention described in claim 1, an efficient fail-safe is realized based on diagnosis of a minimum necessary element of the feedback control system.

According to the third aspect of the invention, in addition to the effect of the first aspect, the vehicle can be evacuated by the forced control of the discharge control valve according to the content of the abnormality. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a high-pressure fuel supply device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a spill valve.

FIG. 3 is a flowchart illustrating feedback control.

FIG. 4 is a time chart illustrating duty control of a solenoid coil. (A) is a duty ratio of 100%,
(B) is a duty ratio of 50%, and (c) is a duty ratio of 0.
%.

FIG. 5 is a flowchart illustrating control when an abnormality occurs in the feedback control system.

FIG. 6 is a schematic configuration diagram showing a fuel supply device according to a conventional technique.

FIG. 7 is a block diagram illustrating the feedback control system.

[Explanation of symbols]

11: High pressure pump, 13: Fuel tank, 14: Low pressure feed pump, 20: Cylinder, 21: Plunger, 22
.., A pressurizing chamber, 40, a pressure regulating valve, 60, an ECU as a feedback control, an abnormality determining means, an energization control means, a gradual change control means (a smoothing control means), 61, a fuel pressure sensor, and E, an engine.

Claims (3)

[Claims] 1. A high-pressure pump which pressurizes fuel transferred from a fuel tank in a pressurized chamber and directly supplies the fuel to an internal combustion engine. A discharge control valve for changing and controlling the fuel pressure;
A fuel pressure sensor that detects the actual fuel pressure of the high-pressure pump, and a feedback control unit that performs feedback control of the energization timing to the discharge control valve so that the detected actual fuel pressure matches a target fuel pressure according to an engine operating state. A high-pressure fuel supply device, comprising: a diagnosing means for diagnosing the presence or absence of an abnormality in the feedback control system; and when the diagnosing means diagnoses an abnormality, the feedback control is stopped to forcibly control the discharge control valve. A high-pressure fuel supply device for an internal combustion engine, comprising: a forced control unit. 2. The high-pressure fuel supply device for an internal combustion engine according to claim 1, wherein said diagnosis means diagnoses whether at least one of a discharge control valve and a fuel pressure sensor is abnormal. 3. The high-pressure fuel supply device for an internal combustion engine according to claim 1, wherein said diagnosis means diagnoses whether or not said fuel pressure detection sensor and said discharge control valve are abnormal. When the diagnosis unit diagnoses that the sensor has an abnormality, the discharge control valve is forcibly controlled so that the fuel pressure of the high-pressure pump becomes maximum. A high-pressure fuel supply device for an internal combustion engine that forcibly controls the discharge control valve to minimize the pressure.