JPH11210532A - High pressure fuel feeder for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a high-pressure fuel supply device for an internal combustion engine that guarantees proper evacuation traveling of a vehicle even when an abnormality occurs in a fuel pressure sensor. A high-pressure fuel injection device provided to supply fuel to an engine is provided with a delivery pipe based on pump operations of a feed pump and a high-pressure pump.
Maintain high pressure fuel inside. The ECU 60 has a fuel pressure sensor 61 for detecting a fuel pressure in the delivery pipe 55.
When an abnormality occurs, the function of the high-pressure pump 11 is stopped. At the same time, using the fuel pressure detected immediately before the occurrence of an abnormality in the fuel pressure sensor 61 as an initial value, the fuel injection time is controlled while estimating the fuel pressure that decreases with each fuel injection, and the engine E is driven to the limp mode. The operation state is shifted to the operation state appropriate for.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure fuel supply device for an internal combustion engine that supplies a required high-pressure fuel to an internal combustion engine mounted on a vehicle.

[0002]

2. Description of the Related Art Conventionally, a device of this type has a low-pressure pump for pumping fuel from a fuel tank into the device, and a process of pumping fuel from the device into an engine (in-vehicle internal combustion engine). Further, it has two pumps, a high-pressure pump for pressurizing, and keeps the fuel introduced into the apparatus at a high pressure by the operation of both pumps (for example,
See Japanese Utility Model Laid-Open No. 5-69374).

FIG. 7 shows a configuration example of this type of high-pressure fuel supply device. As shown in FIG. 7, the high-pressure fuel supply device 100 includes a low-pressure pump (feed 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. The discharge-side passage 106 of the low-pressure fuel pump 101 is connected to the low-pressure regulator 104 via a filter 107.
Further, the low-pressure regulator 104 communicates with 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 111
A high pressure regulator 115 is provided in the middle of a passage 113 returning from the fuel tank 103 to the fuel tank 103.

The common rail 111 has a bank rail 11
8 and the accumulator 116 are connected. An injector 117 is mounted on the bank rail 118. In such a high-pressure pump system, high-pressure fuel discharged from the high-pressure pump 102 is supplied under pressure to the injector 117 of the bank rail 118 via the common rail 111.

On the other hand, such a high-pressure fuel supply device 100
The control unit 120 for controlling the common rail 1
11, a high-pressure regulator 1 based on detection values detected by a fuel pressure sensor 123, an accelerator opening sensor 124, an engine speed sensor 125, and the like.
Feedback control is performed so that the control fuel pressure according to step 15 matches the target fuel pressure. When the feedback correction value based on the detected value exceeds a predetermined range, for example, it is determined that an abnormality has occurred in the fuel pressure sensor 123, and the fact is output to the abnormality display means 126.

[0007]

By the way, in the engine supplied with fuel by the high-pressure fuel supply device as described above, even if the abnormality of the fuel pressure sensor 123 is detected, the operation is stopped immediately. Nevertheless, it is necessary to maintain the driving state at least while the vehicle is evacuated. That is, even if an abnormality occurs in the fuel pressure sensor 123, it is necessary to continue the control related to the fuel pressure supply in some form.

Therefore, as a method of maintaining the fuel supply under pressure even when an abnormality occurs in the fuel pressure sensor 123, the fuel pressure (fuel pressure) of the high-pressure pump 102 is forcibly maintained at a predetermined pressure, and based on the predetermined pressure. It is conceivable that the fuel injection amount is suppressed by the above. For example, high pressure pump 10
2 is stopped, the fuel pressure in the apparatus is reduced to a feed pressure that depends only on the pump operation of the low-pressure pump (feed pump) 101, and the amount of fuel to be injected and supplied is determined based on the feed pressure. .

However, even if the pumping operation of the high-pressure pump 102 is stopped, the fuel pressure does not instantaneously shift to the feed pressure, but shifts to the feed pressure after a certain period of time (generally several seconds). . For this reason, during the transition period of the fuel pressure, the amount of fuel actually injected and supplied becomes inappropriate, and the combustion state of the engine becomes unstable, and there is a possibility that the limp-home traveling cannot be performed properly.

The present invention has been made in view of such circumstances, and has as its object the purpose of an internal combustion engine that ensures proper limp-home running of a vehicle even if an abnormality occurs in a fuel pressure sensor. It is to provide a high-pressure fuel supply device.

[0011]

In order to achieve the above object, according to the present invention, there is provided a high-pressure pump for pressurizing fuel transferred from a fuel tank, and detecting a pressure of the pressurized fuel. A fuel pressure sensor, and an injection valve for injecting the pressurized fuel into the internal combustion engine, and performing feedback control of the pressurized fuel pressure so that the detected fuel pressure becomes a target pressure, In a high-pressure fuel supply device for an internal combustion engine that supplies a predetermined amount of high-pressure fuel to the internal combustion engine through an injection valve according to the operation state, a detection unit that detects an abnormality of the fuel pressure sensor and an abnormality of the fuel pressure sensor is detected. Holding means for forcibly maintaining the fuel pressure at a predetermined pressure, and estimating the fuel pressure until the fuel pressure reaches the predetermined pressure after the abnormality of the fuel pressure sensor is detected. And summarized in that a control means for controlling the injection supplied fuel quantity to the internal combustion engine based on the fuel pressure that is the estimated while.

According to the above configuration, when an abnormality occurs in the fuel pressure sensor, the fuel pressure can be shifted to the predetermined pressure and held, and the fuel injection amount can be controlled while appropriately estimating the fuel pressure during the shift. The transition to limp-home running following the occurrence of an abnormality in the fuel pressure sensor can be performed quickly and accurately.

According to a second aspect of the present invention, in the high-pressure fuel supply device for an internal combustion engine according to the first aspect, a feed pump for transferring fuel from the fuel tank to the high-pressure pump is provided, and the holding means is provided with the predetermined pressure. The gist of the invention is to maintain the feed pressure by the feed pump.

According to the above configuration, since the fuel pressure is shifted to a state lower than the normal state, the pressure load on each unit of the apparatus during the evacuation operation is reduced, and stable evacuation traveling is realized. Will be able to

The third aspect of the present invention provides the first or second aspect.
In the high-pressure fuel supply device for an internal combustion engine according to the above, the control means may use the fuel pressure detected by the fuel pressure sensor immediately before an abnormality of the fuel pressure sensor is detected as an initial value based on the fuel amount to be injected. The gist is that the fuel pressure is sequentially estimated.

According to the first or second aspect of the present invention, although the fuel pressure shifts to a predetermined pressure in accordance with the amount of fuel lost in each fuel injection, according to the third aspect of the present invention, By estimating the change in the fuel pressure from the fuel injection amount to the internal combustion engine that is directly related to the change in the fuel pressure, the fuel pressure during the transition to the predetermined pressure can be estimated with high accuracy. That is, the controllability of the fuel injection amount at the time of shifting to the limp-home mode is further improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a high-pressure fuel supply device for a gasoline engine will be described below.

FIG. 1 shows a schematic configuration of a high-pressure fuel supply device (hereinafter, simply referred to as a fuel supply device) 10 in the present embodiment. The fuel supply device 10 includes a low pressure pump (feed pump) 14, a high pressure pump 11, a spill valve 4
1, a fuel tank 13, a delivery pipe 55, an injector 56, and the like. That is, the feed pump 14 pumps up the fuel in the fuel tank 13 and sends it to the high-pressure pump 11 via the low-pressure oil passage 30. The high-pressure pump 11 pressurizes the fuel sent from the feed pump 14 to a high pressure, and sends the high-pressure fuel to the delivery pipe 55 via the high-pressure oil passage 35. Delivery pipe 55
Stores the high-pressure fuel pumped from the high-pressure pump 11 therein, and injects and supplies the fuel to the engine E through each injector 56 as appropriate.

Next, the details of these components and the manner in which fuel is transferred through the components will be described in further detail with reference to FIG. First, the fuel pumped from the fuel tank 13 by the feed pump 14 is introduced into the space inside the spill valve 41 through the low-pressure oil supply passage 30. The spill valve 41 is connected to the low-pressure oil supply passage 30, is connected to the spill passage 39 via the pressure control valve 40, and has a hole 41 b.
Are connected to the pressurizing chambers 22 of the high-pressure pump 11 through the respective sections. The pressure control valve 40 regulates the backflow of the fuel flowing from the fuel tank 13 to the spill valve 41 side, opens when the fuel pressure in the spill valve 41 becomes equal to or higher than a predetermined pressure, and passes through the spill passage 39. The fuel is returned into the fuel tank 13. The spill valve 41 is a fixed-open solenoid valve,
The valve body 41a is normally urged to the open side by an appropriate urging member. Then, the ECU 6 is connected to the exciting unit 41c.
When the drive signal (duty signal) is applied from 0, the valve element 41a moves to the closing side against the urging force of the urging member. The hole 41b is opened and closed with such an operation of the valve body 41a.

The high-pressure pump 11 pressurizes the fuel to a high pressure, and is formed by a cylinder 20, a plunger 21 reciprocating in the cylinder 20, an inner peripheral wall surface of the cylinder 20, and an upper end surface of the plunger 21. And a pressurized chamber 22. The pressurizing chamber 22 communicates with the spill valve 41 via the hole 41b, and also communicates with the high-pressure oil supply passage 35 via a check valve. High pressure oil passage 35
Are connected to the delivery pipe 55. Check valve 36
Regulates the backflow of fuel from the delivery pipe 55 to the pressurizing chamber 22. The tappet 23 attached to the lower end (the lower end in the figure) of the plunger 21 is, for example, an exhaust camshaft 24 of the engine E by the urging force of a spring (not shown).
Is pressed into contact with a pump drive cam 25 provided at the first position. With the rotation of the exhaust camshaft 24, the pump drive cam 25
Is rotated, the plunger 21 is moved to the cylinder 20.
Reciprocating in the inside, changes the volume in the pressurizing chamber 22.

The fuel that has flowed into the spill valve 41 through the low-pressure oil supply passage 30 is introduced into the pressurizing chamber 22 through the hole 41b when the plunger 21 moves down in the cylinder 20. On the other hand, when the plunger 21 moves upward, the valve body 41a is driven to the closing side based on the energization to the exciting portion 41c to close the hole 41b, and the fuel in the pressurizing chamber 22 is pressurized to a high pressure. Becomes

As described above, the pressurizing chamber 22 of the high-pressure pump 11
The high-pressure fuel pressurized inside is sent to the delivery pipe 55 through the high-pressure oil supply passage 35. Delivery pipe 55
Is for keeping the fuel at a high pressure and distributing and supplying the held fuel to the injectors 56.

Each injector 56 is provided corresponding to each cylinder of the engine E, and each is connected to the delivery pipe 55. When each of the injectors 56 opens and closes based on a drive signal from the ECU 60 of the engine E, a predetermined amount of fuel is injected and supplied to each cylinder of the engine E.

The delivery pipe 55 is connected to a relief passage via a relief valve 37. The relief valve 37 opens when the fuel pressure in the delivery pipe 55 rises to a predetermined pressure or more, and the delivery pipe 55
The fuel in the inside is allowed to flow out to the relief passage 38. The relief passage 38 is configured to join in the middle of the spill passage 39, and the fuel flowing out of the delivery pipe 55 is returned to the fuel tank 13 through the two passages 38 and 39 in order. In this embodiment, the predetermined pressure at which the relief valve 37 is opened is 12 megapascals (MPA).

Incidentally, when the engine E is in a normal operating state, the black spots in the spaces in the passages, the high-pressure pump 11 and the delivery pipe 55 provided in the fuel supply device 10 in FIG. The painted part is filled with high-pressure fuel, and the white part is filled with low-pressure fuel.

On the other hand, a fuel pressure sensor 61 is attached to the delivery pipe 55. Fuel pressure sensor 61 detects fuel pressure PR in delivery pipe 55 and outputs a signal corresponding to the pressure to ECU 60.

The engine E has a rotational speed sensor 62.
Is attached. The rotation speed sensor 62 outputs to the ECU 60 a signal corresponding to the rotation speed of a crankshaft (not shown) of the engine E, that is, the rotation speed NE of the engine E.

Further, an accelerator sensor 64 is attached to the accelerator pedal 63. Accelerator sensor 64
Detects the depression amount of the accelerator pedal 63 and outputs a signal corresponding to the depression amount ACCP to the ECU 60.

Next, the operation of the high-pressure pump 11 provided in the fuel supply device 10 will be described with reference to FIG. 2A, 2B and 2C show an example of the transition of the operation of the high-pressure pump 11, the transition of the lift amount of the plunger 21 and the transition of the opening of the spill valve 41 corresponding to the transition of the operation.

The three operations of the high-pressure pump 11 shown in FIG. 2A correspond to the operations at points A, B and C indicated by arrows in the change of the lift amount shown in FIG. 2B. 2 (b) and 2 (c) use the horizontal axis (time t) of the same scale.

As shown in FIGS. 2A and 2B, the high-pressure pump 11 operates in conjunction with the rotation of a pump drive cam 25 provided at the rear end of the exhaust camshaft 24 of the engine 11. That is, while the plunger 21 moves up and down in the cylinder 20, it sucks the fuel sent by the feed pressure from the feed pump 14 (see FIG. 1), compresses the fuel in the cylinder 20, The operation of discharging toward 35 is repeated. At this time, when the plunger 21 sucks fuel into the cylinder 20 (point A in FIG. 2B),
As shown in FIG. 2C, when the spill valve 41 is opened to allow the fuel flow from the feed pump side, while the plunger 21 starts compressing the fuel in the cylinder 20 (FIG. b) At point B), the spill valve 41 is closed in the manner shown in FIG. Also,
The pressure control valve 40 is opened only when the fuel in the cylinder 20 reaches a predetermined pressure or higher, and sends the accumulated high-pressure fuel to the high-pressure oil supply passage 35 (point C in FIG. 2B). . Through a series of operations of the plunger 21, the spill valve 41, and the pressure control valve 40, the delivery pipe 55 (FIG. 1)
) Is supplied.
As shown in FIG. 2C, the closing timing and the opening degree of the spill valve 41 are duty-controlled by a command from the ECU 60, whereby the high-pressure pump 11 supplies high-pressure fuel to the delivery pipe 55. Is adjusted.

Next, when the fuel supply device 10 configured as described above is driven to inject and supply fuel to the engine E,
A program executed by the ECU 60 to calculate the fuel injection time will be described with reference to a flowchart.

FIG. 3 shows a "fuel injection time calculation routine" showing the processing steps of the same program, which is executed by the ECU 60 as a periodic interruption every predetermined time. When the process proceeds to this routine, the ECU 60 determines in step 100 that the accelerator pedal depression amount ACCP
And various operating state parameters such as the engine speed NE are read.

In the following step 101, the accelerator pedal depression amount ACCP and the engine speed N
The target fuel injection amount Qf based on operating state parameters such as E
To determine. The target fuel injection amount Qf means a single fuel injection amount provided for combustion.

In the following step 102, a correction coefficient Kpr is calculated with reference to a map (not shown) based on the latest value stored in the ECU 60 as the fuel pressure PR in the delivery pipe 55. This correction coefficient Kpr is
This is a coefficient by which the fuel injection amount Qf is multiplied to calculate the fuel injection time TAU, and has a property of decreasing as the fuel pressure PR increases.

In the following step 103, EC
U60 is the fuel injection time TA according to the following equation (1).
U is calculated, and the subsequent processing is temporarily terminated. TAU = Qf × Kpr−β (1) where β is a constant. Thus, the fuel injection time TAU calculated by the series of processing in steps 100 to 103 corresponds to the valve opening time of the injector 56 when fuel is injected into the engine E.

Next, the fuel pressure P in the delivery pipe 55
A program executed by the ECU 60 to calculate R will be described with reference to a flowchart. FIG. 4 is a “fuel pressure calculation routine” showing the processing procedure of the same program, which is executed by the ECU 60 as a periodic interruption every predetermined time.

When the processing is shifted to this routine, EC
U60 checks the upper and lower limits of the detection signal from the fuel pressure sensor 61 in step 201. That is, according to the output voltage VPR from the fuel pressure sensor 61, the fuel pressure sensor 61
It is determined whether or not there is an abnormality.

In this embodiment, if the output voltage VPR from the fuel pressure sensor 61 is within a predetermined range from the lower limit γ to the upper limit δ, it is determined that the fuel pressure sensor 61 is functioning normally. The process moves to step 202. On the other hand, if the output voltage VPR is not within the range from the lower limit γ to the upper limit δ, it is determined that the fuel pressure sensor 61 is abnormal, and the process proceeds to step 204.

In step 202, the process goes to step 203 with the fuel pressure sensor abnormality flag XFPR set to non-setting (XFPR = "0"). Then, in the subsequent step 203, the ECU 60 calculates the current fuel pressure PR according to a known procedure based on the output voltage VPR from the fuel pressure sensor 61 detected this time, stores this as the latest value, and executes the subsequent processing. Stop once.

On the other hand, in step 204, the fuel pressure sensor abnormality flag XFPR is set to "1". Here, as long as the fuel pressure sensor abnormality flag XFPR is set to “1”, the ECU 60 sets the control duty of the spill valve 41 of the high-pressure pump 11 controlled through a separate routine (not shown) to “0”. That is, the spill valve 41 is fully opened.

In the following step 205, the current fuel pressure PR is calculated (estimated) according to the following equation (2). PR = PRn-1-K * Qf (2) where PRn-1 is the fuel pressure calculated in the previous routine PRK is based on the properties of the fuel, the volume of the high-pressure fuel contained in the fuel supply device, and the like. The preset constant Qf is the latest value of the target fuel injection amount. That is, immediately before the abnormality of the fuel pressure sensor 61 is detected in step 201, the detection signal V from the fuel pressure sensor 61 is detected.
With the fuel pressure PR calculated based on the PR as an initial value, the fuel pressure PR is estimated assuming that the fuel pressure PR decreases by a constant (K) times the target fuel injection amount Qf.

In the following step 206, the fuel pressure PR estimated in the step 205 becomes the predetermined pressure P
It is determined whether it is lower than Rf. This predetermined pressure P
Rf corresponds to the fuel pressure in the delivery pipe 55 that can be maintained by the pump operation of the feed pump 14 alone. If the determination is affirmative, the ECU 60 shifts the processing to step 207. If the determination is negative, the ECU 60 stores the calculated (estimated) fuel pressure PR as the latest value, and once ends the subsequent processing. I do.

In step 207, the ECU 60 stores the predetermined pressure PRf as the latest value, and terminates the subsequent processing once. That is, the fuel pressure sensor abnormality flag XFP
After R is set to “1”, the minimum value of the fuel pressure PR estimated in step 205 is set as a preset feed pressure PRf, and the fuel pressure PR calculated by the above equation (2) is equal to the feed pressure PRf. When the pressure falls below the lower limit, the fuel pressure PR is considered to be equal to the feed pressure PRf, and the lower limit is guarded.

FIG. 5 shows the transition of the fuel pressure sensor abnormality flag XFPR when an abnormality occurs in the fuel pressure sensor 61 (FIG. 5).
(A)), the transition of the control duty relating to the opening / closing operation of the spill valve 41 (FIG. 5 (b)), the transition of the fuel pressure PR in the delivery pipe 55 of the fuel supply device 10 (FIG. 5).
(C)) is shown. 5 (a) to 5 (c).
, The horizontal axis as the time axis is all on the same scale.

That is, before the time ta, the fuel pressure sensor 61
Is normal, the fuel pressure sensor abnormality flag XFPR is in a non-set state (XFPR =
"0"). At this time, the spill valve 41
The opening is adjusted by a control duty in a predetermined range output by the CU 60 (FIG. 5B), and the fuel pressure PR in the delivery pipe 55 is adjusted to a predetermined pressure PRh (this embodiment) according to the opening of the spill valve 41. 10MPA) is maintained.

However, if an abnormality occurs in the fuel pressure sensor 61 at time ta, the ECU 60 recognizes the abnormality and sets the fuel pressure sensor abnormality flag XFPR to "1" as described in the "fuel pressure calculation routine". (FIG. 5A). Then, together with this flag setting, the control duty of the spill valve 41 is set to 0% (FIG. 5).
(B)) The pump function of the high-pressure pump 11 is stopped.

After time ta, the high-pressure pump 11
With the stop of the pump function, the pressure in the delivery pipe 55 gradually decreases in accordance with the (target) fuel injection amount Qf for each fuel injection by the injector 56. However, even if the high-pressure pump 11 is not functioning, the fuel pressure PR in the delivery pipe 55 is maintained at least at a predetermined feed pressure PRf (in the present embodiment, approximately 0.3 MPa) by the pump function of the feed pump 14. The Rukoto. For this reason, as shown in FIG. 5C, after a predetermined time has elapsed from time ta, the fuel pressure PR in the delivery pipe reaches this feed pressure PRf and becomes a steady state.

By the way, the "fuel pressure calculation routine"
In equation (2), the coefficient K by which the target fuel injection amount Qf is multiplied to estimate the fuel pressure PR is a constant, as shown in the equation (2). If the injection amount is constant, FIG.
As shown in (c), the fuel pressure P estimated by the ECU 60
R is attenuated (linearly) at a constant rate in each processing routine until the feed pressure PRf is reached.

Here, in the present embodiment, as described above, the ECU 60 stops the pump function of the high-pressure pump 11 based on the detection of the abnormality of the fuel pressure sensor 61, and thereafter, the abnormality occurs in the fuel pressure sensor 61. The fuel pressure detected immediately before the start is set as an initial value, and the fuel pressure until the steady state is reached is successively estimated. Moreover, when estimating the fuel pressure, the fuel pressure (change pressure Δ) in the delivery pipe, which is consumed every time fuel is injected into the engine, is determined.
PR) is uniquely related to a single fuel injection amount, and therefore, calculation is performed based on the (target) fuel injection amount Qf. That is, in this embodiment, the pressure reduction amount in the delivery pipe for each fuel injection is set to be a constant (K) times the target fuel injection amount Qf. The high-pressure pump 11
Considering that the oil supply to the delivery pipe 55 by the feed pump 14 is continued even after the pump function is stopped, the feed pressure PRf is changed to the estimated fuel pressure PR.
Is set as the closing price (lower limit value).

Therefore, even during the transition period up to the feed pressure PRf, by calculating the highly reliable estimated fuel pressure, it is possible to maintain precise fuel injection control based on the estimated fuel pressure. . After the fuel pressure PR becomes the feed pressure PRf, the operation of the feed pump 14 causes the fuel pressure PR to also become the feed pressure Pf.
Stabilizes as Rf. Therefore, even when the fuel pressure sensor 61 becomes abnormal, it is possible to realize a suitable limp-home running without applying a pressure load to each part constituting the fuel supply device 10.

As described above, according to the present embodiment in which the high-pressure fuel supply is controlled in the above-described manner, the following effects can be obtained. Even if an abnormality occurs in the fuel pressure sensor 61, it is possible to maintain a precise fuel injection control and appropriately shift to the limp-home mode. -Since the fuel pressure is maintained at the feed pressure after the abnormality of the fuel pressure sensor 61, it is possible to maintain a suitable limp-home running without imposing a pressure load on each part constituting the fuel supply device.

In this embodiment, the present invention is embodied as a high-pressure fuel supply device for a gasoline engine. For example, the present invention is also applied to a diesel engine having a common rail type high-pressure fuel supply device. You can.

In this embodiment, a normally-open solenoid valve is used as the spill valve 41. However, a normally-closed solenoid valve may be employed. In this case, the fuel pressure sensor 61
When the abnormality occurs, the control duty of the solenoid valve is set to 1
What is necessary is just to comprise so that it may be set to 00% and a full open state may be maintained. Further, when an abnormality occurs in the fuel pressure sensor 61, the spill valve 41 may not be in the fully open state, but may be in a half-open state or a slightly open state using a predetermined control duty. That is, control may be performed so that the fuel pressure in the delivery pipe 55 is maintained at a predetermined pressure or less and a constant pressure.

Further, in this embodiment, the fuel pressure sensor 61
When an abnormality occurs in the delivery pipe 55, the function of the high-pressure pump 11 is stopped to reduce the fuel pressure in the delivery pipe 55 to the feed pressure. May be maintained at the maximum fuel pressure. In this case, the fuel pressure of the delivery pipe 55 is maintained at the lower limit pressure (12 MPa in the present embodiment) for opening the relief valve 37.

In any of these cases, until the fuel pressure in the delivery pipe or the common rail reaches a predetermined pressure and becomes steady, the fuel pressure is estimated according to the above-described embodiment, and the estimated fuel pressure is determined. By performing the fuel injection control on the basis of the above, appropriate limp-home running can be guaranteed.

In the present embodiment, when an abnormality occurs in the fuel pressure sensor 61, the amount of attenuation of the fuel pressure PR is uniquely estimated from the target fuel injection amount Qf for each time. In addition, parameters that may affect the physical properties of the fuel may be added. With this configuration, the reliability of the estimation of the fuel pressure is further improved.

In the present embodiment, as shown in the "fuel injection time calculation routine" illustrated in FIG. 3 and the "fuel pressure calculation routine" illustrated in FIG. A fuel pressure (attenuation amount of the fuel pressure) is estimated, and a correction coefficient K is calculated based on the estimated fuel pressure.
pr (a correction coefficient for calculating the fuel injection time TAU from the target fuel injection amount Qf) is calculated. On the other hand, the estimated change rate (ΔPR / fuel injection) of the fuel pressure PR corresponding to some operation modes such as the idling operation, the steady operation, and the acceleration operation may be set in advance as a constant.

In the present embodiment, the "fuel pressure calculation routine" (FIG. 4) for calculating the fuel pressure PR in the delivery pipe 55 includes the "fuel injection time calculation time" for calculating the fuel injection time TAU. The "calculation routine" (FIG. 3) is basically an independent routine, which is executed by a periodic interruption. On the other hand, for example, FIG.
As shown in the figure, during the processing procedure of the "fuel injection time calculation routine" as the main routine, the processing corresponding to the "fuel pressure calculation routine" is executed in a subroutine (step 20).
0). With this configuration, the fuel pressure PR can be reliably determined in the subroutine based on the final fuel injection amount Qf determined each time in the main routine.
Is calculated, and the final fuel injection amount Qf and the fuel pressure P
Processing for calculating the fuel injection time TAU based on R is sequentially and reliably executed. Thus, when an abnormality occurs in the fuel pressure sensor 61, the transition to the evacuation operation can be appropriately performed without causing the unstable combustion state of the engine E.

Further, in the present embodiment, the control routine is configured to determine that the fuel pressure sensor 61 is abnormal if the output voltage VPR from the fuel pressure sensor 61 is not within the predetermined range. This is because this kind of output voltage abnormality is often caused by disconnection or short circuit of the electric system related to the fuel pressure sensor 61. However, the abnormality detection of the fuel pressure sensor 61 may employ another detection method for detecting the presence or absence of the abnormality of the sensor 61 based on factors other than the connection state of the electric system.

Finally, technical ideas other than the claims that can be understood from the above embodiments will be described below together with their effects. (1) The fuel transferred from the fuel tank is pressurized by a high-pressure pump, the pressure of the pressurized fuel is detected by a fuel pressure sensor, and the pressure is adjusted so that the detected fuel pressure becomes a target pressure. When performing feedback control of the fuel pressure to be compressed and injecting a predetermined amount of high-pressure fuel from the injection valve to the engine according to the operation state of the internal combustion engine to the engine, when the abnormality of the fuel pressure sensor is detected, the fuel pressure is forcibly increased. After the fuel pressure sensor detects an abnormality in the fuel pressure sensor, and until the fuel pressure reaches the predetermined pressure, the fuel supply sensor estimates the fuel pressure based on the estimated fuel pressure. A high-pressure fuel supply method for an internal combustion engine for controlling the amount of fuel to be supplied.

According to the method (1), when an abnormality occurs in the fuel pressure sensor, the fuel pressure is shifted to a predetermined pressure, and the fuel injection amount is controlled while appropriately estimating the fuel pressure during the shift. Therefore, the transition to the evacuation operation due to the occurrence of the abnormality in the fuel pressure sensor can be performed quickly and accurately.

(2) In the high-pressure fuel supply method for an internal combustion engine according to the above (1), when an abnormality of the fuel pressure sensor is detected, the fuel pressure is changed to a feed pressure for transferring fuel from the fuel tank to the high-pressure pump. A high-pressure fuel supply method for an internal combustion engine, characterized by maintaining a feed pressure by a pump.

According to the above method (2), the fuel pressure is shifted to a state lower than the normal state, so that the load on each part of the apparatus during the evacuation operation is reduced, and the stable evacuation traveling state is achieved. Can be obtained.

(3) In the high-pressure fuel supply method for an internal combustion engine according to the above (1) or (2), when an abnormality of the fuel pressure sensor is detected, the abnormality is detected by the fuel pressure sensor immediately before the abnormality is detected. A high-pressure fuel supply method for an internal combustion engine, wherein the fuel pressure is sequentially estimated based on the fuel amount to be injected and supplied with the fuel pressure as an initial value.

In the above method (1) or (2), the fuel pressure shifts to a predetermined pressure according to the amount of fuel lost in each fuel injection, but according to the method (3),
By estimating the change in fuel pressure from the amount of fuel injected into the internal combustion engine that is directly related to the change in fuel pressure, the fuel pressure during the transition to the predetermined pressure can be estimated with high accuracy. In addition, the controllability of the fuel injection amount at the time of shifting to the limp mode is further improved.

[0067]

According to the first aspect of the invention, when an abnormality occurs in the fuel pressure sensor, the fuel pressure is shifted to and maintained at a predetermined pressure, and the fuel injection amount is adjusted while appropriately estimating the fuel pressure during the shift. Since the control can be performed, the shift to the limp-home mode due to the occurrence of the abnormality in the fuel pressure sensor can be performed quickly and accurately.

According to the second aspect of the present invention, the fuel pressure is shifted to a state lower than the normal state.
The pressure load on each unit of the device during the evacuation operation is reduced, and stable evacuation traveling can be realized.

According to the first or second aspect of the present invention, according to the fuel amount lost in each fuel injection,
Although the fuel pressure shifts to the predetermined pressure, according to the invention described in claim 3, the change in the fuel pressure is estimated from the fuel injection amount to the internal combustion engine which is directly related to the change in the fuel pressure. Therefore, the fuel pressure during the transition to the predetermined pressure can be estimated with high accuracy,
The controllability of the fuel injection amount at the time of shifting to the limp mode is further improved.

[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 time chart showing an operation mode of the high-pressure pump.

FIG. 3 is a flowchart showing a fuel injection time calculation procedure of the embodiment.

FIG. 4 is a flowchart showing a fuel pressure calculation procedure of the embodiment.

FIG. 5 is a time chart showing how the fuel pressure changes before and after the fuel pressure sensor detects an abnormality.

FIG. 6 is a flowchart illustrating another processing procedure related to fuel injection time calculation.

FIG. 7 is a block diagram showing a schematic configuration of a conventional high-pressure fuel supply device.

[Explanation of symbols]

11 ... High pressure pump, 13 ... Fuel tank, 14 ... Feed pump (low pressure pump), 20 ... Cylinder, 21 ... Plunger, 22 ... Pressure chamber, 30 ... Low pressure oil passage, 35 ... High pressure oil passage, 37 ... Relief Valve, 38 ... relief passage, 39 ...
Spill passage, 40: pressure regulating valve, 41: spill valve, 55
... Delivery pipe, 56 ... Injector, 60 ... ECU
(Electronic control device), 61: fuel pressure sensor, E: engine.

Claims (3)

[Claims] 1. A high-pressure pump for pressurizing fuel transferred from a fuel tank, a fuel pressure sensor for detecting the pressure of the pressurized fuel, and an injection valve for injecting the pressurized fuel to an internal combustion engine. An internal combustion engine that supplies a predetermined amount of high-pressure fuel to the internal combustion engine through the injection valve while performing feedback control of the fuel pressure to be increased so that the detected fuel pressure becomes a target pressure. In the high-pressure fuel supply device of the engine, a detection unit that detects an abnormality of the fuel pressure sensor; a holding unit that forcibly holds the fuel pressure at a predetermined pressure based on the detection of the abnormality of the fuel pressure sensor; After the abnormality of the sensor is detected, the fuel to be injected to the internal combustion engine based on the estimated fuel pressure while estimating the fuel pressure until the fuel pressure reaches the predetermined pressure. High-pressure fuel supply system for an internal combustion engine, characterized in that it comprises a control means for controlling. 2. A high-pressure fuel supply device for an internal combustion engine according to claim 1, further comprising a feed pump for transferring fuel from said fuel tank to said high-pressure pump, wherein said holding means uses said feed pump as said predetermined pressure. A high-pressure fuel supply device for an internal combustion engine, wherein the fuel pressure is maintained at a feed pressure. 3. The control means sequentially estimates a fuel pressure based on the amount of fuel to be injected with the fuel pressure detected by the fuel pressure sensor as an initial value immediately before the abnormality of the fuel pressure sensor is detected. The high-pressure fuel supply device for an internal combustion engine according to claim 1 or 2, wherein