JP4421451B2 - Abnormality detection device for fuel supply system for internal combustion engine - Google Patents

Description

  The present invention relates to an abnormality detection device for a fuel supply system used in, for example, an in-cylinder injection gasoline engine for vehicles, and more particularly to a fuel for an internal combustion engine that supplies fuel to a fuel injection valve for injecting high-pressure pressurized fuel. The present invention relates to an abnormality detection device for a supply system.

  A fuel supply system used for an internal combustion engine for an automobile includes a plurality of fuel injection valves for injecting fuel into each cylinder of the internal combustion engine, a delivery pipe for supplying fuel to these fuel injection valves, and a pressure in the delivery pipe A high-pressure regulator that adjusts fuel pressure, a high-pressure pump that supplies pressurized fuel to the delivery pipe, a low-pressure pump that supplies the fuel in the fuel tank to the high-pressure pump, and the timing and amount of fuel injected into the fuel injection valve It consists of an electronic control unit.

The high-pressure pump is composed of a cylinder and a pump piston.
The pump piston is driven by a pump driving cam provided on a rotating shaft (for example, a cam shaft) of the internal combustion engine, reciprocates in the cylinder, and sucks fuel into the pressurized chamber in the suction stroke, and in the discharge stroke. The fuel in the pressurized chamber is pumped to the delivery pipe.

  The high-pressure regulator adjusts the flow rate of returning excess fuel from the high-pressure pump discharge fuel into the fuel tank by opening and closing a valve provided at one end of the cylinder, and adjusts the fuel pressure in the delivery pipe to a predetermined set pressure. It comes to hold.

  However, due to the operating principle of the high-pressure regulator as described above, even if the high-pressure regulator is in a normal state, the fuel pressure is reduced due to a minute leak from the valve in a state where the flow rate of the high-pressure regulator is very small. In some cases, the pressure cannot be maintained at a predetermined set pressure. Further, in a mechanical high-pressure regulator that adjusts the opening and closing of a valve with a spring, a certain gradient occurs in the set pressure with respect to the flow rate of the high-pressure regulator.

On the other hand, the fuel pressure in the delivery pipe may deviate from the set pressure due to an abnormality in the fuel supply system.
As a method for detecting such an abnormality, an apparatus for detecting an abnormality of the fuel supply system based on the high pressure pump discharge amount and the injection amount command value in addition to the fuel pressure has been proposed (see, for example, Patent Document 1).

  In this case, the comparison value (magnitude relationship) between the integrated value of the discharge amount of the high-pressure pump and the integrated value of the injection amount from the fuel injection valve is a parameter for estimating the behavior of the actual fuel pressure under normal conditions. ) And the actually detected fuel pressure as abnormality diagnosis parameters, it is possible to determine abnormality of the fuel supply system.

JP 2002-47983 A

However, in the conventional abnormality detection device for a fuel supply system for an internal combustion engine described in Patent Document 1, an abnormality detection target is a fuel supply system that controls the fuel discharge amount of a high-pressure pump. Since the flow rate of the fuel returning to the fuel tank is not taken into consideration, there is a problem that the abnormality detection accuracy may be deteriorated or the abnormal state may be erroneously detected.
For example, if the integrated value of the discharge amount of the high-pressure pump and the injection amount of the fuel injection valve is compared, the fuel pressure drops even though the discharge amount integrated value exceeds the injection amount integrated value. If there is a state in which the injection amount of the fuel injection valve is larger than the discharge amount of the high-pressure pump during the integration, it is actually normal due to the high-pressure regulator characteristics on the downstream side of the high-pressure pump. Therefore, there is a problem that the fuel pressure may decrease and there is a possibility that an abnormal state may be erroneously determined.

  This invention has been made to solve the above problems, and by using the amount of fuel discharged from the high-pressure pump and the flow rate of the high-pressure regulator estimated from the injection amount as parameters for abnormality detection, An object of the present invention is to obtain an abnormality detection device for a fuel supply system for an internal combustion engine with improved abnormality detection accuracy.

An abnormality detection device for a fuel supply system for an internal combustion engine according to the present invention comprises:
A fuel injection valve that individually injects fuel into each cylinder of the internal combustion engine, a delivery pipe that supplies pressurized fuel to the fuel injection valve, a pump drive cam that is driven by the internal combustion engine, and a pump drive cam that is driven by the pump drive cam. A high-pressure pump that discharges pressurized fuel to the pipe, a high-pressure regulator that is provided downstream of the high-pressure pump and adjusts the pressure of the fuel discharged from the high-pressure pump, and a fuel pressure detection means that detects the fuel pressure in the delivery pipe A high-pressure regulator flow estimation means for obtaining a high-pressure regulator estimated flow corresponding to the flow of the high-pressure regulator, and an abnormality detection means for detecting an abnormality in the fuel supply system. The regulator flow rate estimating means is a high-pressure pump discharge estimated fuel amount calculated based on the rotational speed of the internal combustion engine. , Using the fuel amount deviation between the required fuel injection amount which is calculated based on the operating state of the internal combustion engine, obtains a high-pressure regulator likely flow rate, the abnormality detecting means, and pressure regulator estimated lower than the set fuel pressure of the high-pressure regulator comparing the abnormality determination value and the fuel pressure is set so as to decrease as the flow rate decreases, when the fuel pressure is lower than the abnormality determination value, thereby determining the fuel supply system is abnormal, the high-pressure regulator When the estimated flow rate of the high-pressure regulator is lower than the predetermined flow rate that determines the region where the set fuel pressure that is the adjustment target in the normal state cannot be maintained when the flow rate decreases , the fuel supply system abnormality detection is prohibited. To do.

  According to the present invention, an abnormality in the fuel supply system can be detected with high accuracy by using the amount of fuel discharged from the high-pressure pump and the flow rate of the high-pressure regulator estimated from the injection amount of the fuel injection valve.

Embodiment 1 FIG.
Hereinafter, an abnormality detection device for a fuel supply system for an internal combustion engine according to Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an abnormality detection device for a fuel supply system for an internal combustion engine according to Embodiment 1 of the present invention, showing an example applied to a four-cylinder direct injection internal combustion engine.
FIG. 2 is a system diagram schematically showing the line configuration of the fuel supply system together with each block in FIG. 1, and specifically shows the configuration related to the high-pressure pump.

In FIG. 1, an internal combustion engine (engine) 101 for a vehicle is provided with a fuel supply system, an ignition system, and a control system in addition to an intake system and an exhaust system.
The intake system of the internal combustion engine 101 includes an air cleaner 102 that purifies the intake air of the internal combustion engine 101, an air flow sensor 103 that measures the amount of intake air to the internal combustion engine 101, an intake pipe 104 that sends the intake air to the internal combustion engine 101, And a throttle valve 105 for adjusting the amount of intake air.

The fuel supply system includes a fuel injection valve 106, a high-pressure pump 140 associated with the camshaft 110, and an injector driver 151.
The fuel injection valve 106 is individually provided in the combustion chamber of each cylinder of the internal combustion engine 101, and is driven via an injector driver 151 under the control of an ECU (electronic control unit) 150, whereby the internal combustion engine An injection amount of fuel commensurate with the operation state 101 is supplied into the combustion chamber.

  The spark plug 130 constituting the ignition system is driven by the ignition coil 131 under the control of the ECU 150, generates a spark by the high voltage supplied from the ignition coil 131, and burns the air-fuel mixture in the combustion chamber.

  The exhaust system of the internal combustion engine 101 includes an exhaust pipe 107 that exhausts exhaust gas burned in the combustion chamber, an O2 sensor 108 that detects the oxygen concentration in the exhaust gas, and a three-way catalyst 109 that purifies the exhaust gas. The

A signal plate 121 is attached to a crankshaft 120 that is rotationally driven by the internal combustion engine 101, and a sensor 122 made of an electromagnetic pickup is disposed opposite to the signal plate 121.
The signal plate 121 and the sensor 122 constitute a crank angle sensor, and the sensor 122 generates a crank angle signal by detecting an outer peripheral protrusion of the signal plate 121.
The crank angle signal is input to the ECU 150 and serves as a reference for calculation timing such as ignition timing, fuel injection timing, and injection amount. Further, the engine rotational speed Ne is obtained from the cycle of the crank angle signal.

The camshaft 110 is connected to the crankshaft 120 through mechanical transmission means (not shown) such as a timing belt, and rotates once while the crankshaft 120 rotates twice.
A signal plate 111 is attached to the camshaft 110, and a sensor 112 made of an electromagnetic pickup is disposed opposite to the signal plate 111.
The signal plate 111 and the sensor 112 constitute a cam angle sensor, and the sensor 112 generates a cam signal by detecting an outer peripheral protrusion of the signal plate 111.
The cam signal is input to the ECU 150 and serves as a cylinder position reference.

  The ECU 150 constituting the control means includes a CPU and a memory (not shown), determines the operating state of the internal combustion engine 101 based on detection information from various sensors such as the sensors 112 and 122, the fuel injection valve 106, Various actuators such as an ignition coil 131, an electromagnetic valve (not shown) in the high-pressure pump 140, and an injector driver 151 are driven.

In FIG. 2, fuel injection valves 106a to 106d are individually provided for each of the four cylinders of the internal combustion engine 101, and inject fuel into the combustion chambers of the respective cylinders.
A delivery pipe 162 for discharging pressurized fuel to the fuel injection valves 106a to 106d is connected to the fuel injection valves 106a to 106d.

The delivery pipe 162 keeps the pressure of the fuel pressurized by the high pressure pump 140 at the target pressure, and supplies the high pressure fuel to the fuel injection valves 106a to 106d.
The high-pressure pump 140 is driven by a pump drive cam 146, and the pump drive cam 146 is driven by the internal combustion engine 101 via the cam shaft 110.
A fuel pressure sensor 163 is provided at one end of the delivery pipe 162, and the fuel pressure sensor 163 detects the fuel pressure Fp in the delivery pipe 162 and inputs it to the ECU 150.

  A high pressure regulator 141 is provided on the downstream side of the high pressure pump 140, and the high pressure regulator 141 adjusts the pressure of the fuel discharged from the high pressure pump 140 to a predetermined set pressure. The adjustment pressure by the high pressure pump 140 substantially corresponds to the fuel pressure Fp in the delivery pipe 162.

  In the high-pressure pump 140, the pressurizing cylinder includes a pressurizing chamber 142, a check valve 143 that opens and closes an opening of the pressurizing chamber 142, and a pump piston 145 having a spring 144.

  The pump piston 145 is urged in a direction protruding from the cylinder by a spring 144, and a tip portion thereof is pressed in synchronization with the rotation of the internal combustion engine 101 by a pump drive cam 146 integrated with the camshaft 110. The inside of the pressurizing chamber 142 is reciprocated to discharge the fuel in the pressurizing chamber 142 toward the delivery pipe 162 while pressurizing the fuel.

A fuel outlet (described later) of the high-pressure regulator 141 in the high-pressure pump 140 is in communication with the fuel tank 160.
Further, the fuel intake port of the cylinder in the high-pressure pump 140 is communicated with the fuel tank 160 via the low-pressure pump 161.

As shown in FIG. 2, the high pressure pump 140 is driven by a pump drive cam 146 provided on the camshaft 110 of the internal combustion engine 101 to supply pressurized fuel to the delivery pipe 162.
In the high-pressure pump 140, the pump piston 145 is driven by a pump drive cam 146 to reciprocate in the cylinder, sucking fuel into the pressurizing chamber 142 and pressurizing, and the spring 144 expands the pressurizing chamber 142. The pump piston 145 is always urged in the direction.

  That is, the pump piston 145 pressurizes the fuel in the pressurizing chamber 142 and discharges it to the delivery pipe 162 when the lift portion of the pump drive cam 146 rises as the internal combustion engine 101 rotates.

At this time, the low pressure pump 161 supplies fuel from the fuel tank 160 to the cylinder in the high pressure pump 140.
The check valve 143 is disposed at the fuel intake port and the fuel discharge port of the cylinder, and performs fuel intake into the cylinder and fuel discharge from the cylinder.

FIG. 3 is a cross-sectional view specifically showing the high-pressure regulator 141 in the high-pressure pump 140, and shows an example of a configuration in which the target fuel pressure is fixedly set to a predetermined pressure.
In FIG. 3, the high pressure regulator 141 includes a valve seat 201 and a fuel inlet 202 communicated with a fuel discharge port of a cylinder, a pipe 203, a valve 204 that opens and closes the pipe 203, and a spring 205 provided in the pipe 203. And a fuel outlet 206 provided on the side surface of the pipe 203 and communicated with the fuel tank 160.

In the high pressure regulator 141, the fuel introduced from the high pressure (cylinder discharge port) side through the passage formed by the valve seat 201, the fuel inlet 202 and the valve 204 is applied to the valve 204 by the fuel pressure and the spring 205. The flow rate is adjusted according to the balance with the urging force, and is returned to the low-pressure side fuel tank 160 via the fuel outlet 206.
As a result, the fuel pressure on the high pressure side is adjusted to a predetermined pressure set in advance.

FIG. 4 is an explanatory diagram showing the characteristics of the high pressure regulator 141, and shows the relationship of the fuel pressure (vertical axis) to the high pressure regulator flow rate (horizontal axis).
In FIG. 4, the solid line indicates the fuel pressure with the set fuel pressure (7 [MPa]) as the adjustment target, and the one-dot chain line indicates the abnormality determination value Fp_fail.
The flow rate of the high pressure regulator 141 is set to 50 [L / h], and the fuel pressure on the high pressure side of the high pressure regulator 141 is set to 7 [MPa].

As shown in FIG. 4, in the region where the flow rate of the high pressure regulator 141 is less than about 1 [L / h], the high pressure fuel pressure cannot be maintained at the set fuel pressure (= 7 [MPa]).
In addition, the fuel pressure (see the solid line) has a gradient of about 1 [MPa] within the operating flow rate range with respect to the flow rate of the high pressure regulator 141.
Therefore, the abnormality determination value Fp_fail for the fuel pressure Fp is set in consideration of a margin such as a variation of about 1 [MPa].

FIG. 5 is an explanatory diagram showing the characteristics of the high-pressure pump 140, and shows the relationship of the fuel discharge amount (vertical axis) to the engine rotational speed Ne (horizontal axis).
In FIG. 5, the fuel discharge amount of the high-pressure pump 140 is a value approximately proportional to the engine speed Ne, although the efficiency slightly decreases on the low rotation side of the internal combustion engine 101, and is about 90 [L / h] at the maximum in the use range. Reach.

The ECU 150 includes high pressure regulator flow rate estimating means for obtaining the high pressure regulator estimated flow rate Qreg, and abnormality detecting means for detecting an abnormality in the fuel supply system.
The high pressure regulator flow rate estimation means in the ECU 150 is a fuel of a discharge estimated fuel amount Qp of the high pressure pump 140 calculated based on the engine speed Ne and a required injection fuel amount calculated based on the operating state of the internal combustion engine 101. A high-pressure regulator estimated flow rate Qreg is obtained based on the quantity deviation.

The abnormality detection means in the ECU 150 detects an abnormality of the fuel supply system based on the high pressure regulator estimated flow rate Qreg obtained by the high pressure regulator flow rate estimation means and the fuel pressure Fp detected by the fuel pressure sensor 163. .
Specifically, the abnormality detection means determines that the fuel supply system is abnormal when the fuel pressure Fp is lower than the abnormality determination value calculated according to the high pressure regulator estimated flow rate Qreg.

FIG. 6 is a timing chart showing an example of the behavior of each parameter according to the first embodiment of the present invention, and shows the time change of each parameter in the acceleration / deceleration operation state in the four-cylinder direct injection internal combustion engine.
In FIG. 6, in relation to the change in the engine speed Ne, the estimated fuel amount Qp of the high-pressure pump 140, the injection amount Qcyl per stroke, the required injected fuel amount Qinj, the high-pressure regulator estimated flow rate Qreg, and the fuel pressure Fp are Each changes like a solid line.

The fuel pressure Fp behaves like a dotted line at the time of abnormality, and is below the abnormality determination value Fp_fail (refer to the one-dot chain line).
The abnormality detection flag f_fail is cleared to “0 (normal)” if the fuel pressure Fp is equal to or higher than the abnormality determination value Fp_fail, but “1 (abnormal)” if the fuel pressure Fp falls below the abnormality determination value Fp_fail. Set to

Here, each parameter in FIG. 6 will be described in order from the top.
The engine rotation speed Ne is obtained from the crank angle signal from the sensor 122 as described above.
In FIG. 6, the engine rotational speed Ne increases from the initial rotational speed due to acceleration and enters a high rotational state. After maintaining the high rotational state for a certain period of time, the engine rotational speed Ne is decelerated and returns to the initial rotational speed.

The estimated discharge fuel amount Qp of the high-pressure pump 140 is calculated according to the characteristic data of FIG. 5 and the engine speed Ne.
Note that the discharge amount characteristic of the high-pressure pump 140 shown in FIG. 5 is stored in advance in the memory in the ECU 150 as data.

The injection amount Qcyl per stroke commensurate with the operating state of the internal combustion engine 101 increases because the load becomes high during acceleration, while “0” because fuel cut is executed during deceleration. Set to
The required injection fuel amount Qinj per unit time is obtained from the injection amount Qcyl per stroke for comparison with the estimated discharge fuel amount Qp of the high-pressure pump 140.
For example, during the acceleration, the required injection fuel amount Qinj increases as shown in the figure even if the injection amount Qcyl per stroke is constant because the engine rotation speed Ne increases and the number of injections increases.

The high pressure regulator estimated flow rate Qreg is obtained by subtracting the required injection fuel amount Qinj from the estimated discharge fuel amount Qp of the high pressure pump 140.
The high-pressure regulator estimated flow rate Qreg tends to decrease in a low-rotation and high-load operation state according to each parameter characteristic, and conversely, increases as the high-rotation and low-load operation state is reached.

  Under normal conditions, the fuel pressure Fp in the delivery pipe 162 measured by the fuel pressure sensor 163 rises as the high pressure regulator estimated flow rate Qreg increases according to the characteristics of the high pressure regulator 141 (see FIG. 4). It drops as the regulator estimated flow rate Qreg decreases.

Further, the abnormality determination value Fp_fail (refer to the one-dot chain line) to be compared with the fuel pressure Fp is obtained according to the high-pressure regulator estimated flow rate Qreg as shown in FIG.
As described above, the abnormality detection fuel pressure Fp_fail is set in accordance with the change of the fuel pressure Fp due to the characteristics of the high pressure regulator 141, and when Fp <Fp_fail, it is determined that the fuel pressure Fp is in an abnormal state. High-precision abnormality detection can be realized regardless of changes.

  The abnormality detection flag f_fail indicating an abnormal state is set to “0” when it is normal, and is set to “1” when indicating an abnormality (Fp <Fp_fail).

Next, a basic processing operation of ECU 150 according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a flowchart showing a processing procedure of the ECU 150 executed at a cycle of 180 ° [CA: crank angle] with reference to the crank angle signal.

FIG. 8 is a flowchart showing the high-pressure regulator estimated flow rate calculation process (step S106) in FIG. 7, and FIG. 9 is a flowchart showing the abnormality detection process (step S107) in FIG.
FIG. 10 is a flowchart showing fuel pressure calculation processing executed at a cycle of 1 [msec].

First, the processing of the ECU 150 will be described with reference to FIG.
In FIG. 7, the ECU 150 calculates the engine rotation speed Ne from the cycle of the crank angle signal (step S101), and calculates the fuel pressure Fp by the following equation using the variables FPsum and C_FPsum for fuel pressure sampling ( Step S102).

  Fp = FPsum / C_FPsum

Subsequently, each variable FPsum and C_FPsum is cleared to 0 and initialized (steps S103 and S104), and an injection amount calculation process (step S105) is executed.
In step S105, the injection amount Qcyl per stroke is calculated based on the operating state of the internal combustion engine 101.
Finally, calculation processing (step S106) and abnormality detection processing (step S107) of the high-pressure regulator estimated flow rate Qreg used in the abnormality detection processing are executed.

Next, the calculation process (step S106) of the high-pressure regulator estimated flow rate Qreg in FIG. 7 will be described with reference to FIG.
In FIG. 8, first, the ECU 150 calculates the estimated fuel amount Qp of the high-pressure pump 140 using map data map1 (Ne) using the engine speed Ne as a parameter (step S201).
At this time, it is desirable that the map data map1 (Ne) is set by reducing the variation based on the discharge amount characteristic of the high-pressure pump 140 (see FIG. 4).

  Subsequently, the required injection fuel amount Qinj is obtained by the following equation using the injection amount Qcyl per stroke calculated in step S105 in FIG. 7 and the engine speed Ne (step S202).

  Qinj = Qcyl × Ne × k

Here, the value of the coefficient k is k = 1.2 with respect to the required injection fuel amount Qinj [L / h], the injection amount Qcyl [mm ³ ] per stroke, and the engine speed Ne [r / min]. × 10 ^-4 is set.
Finally, using the estimated discharge fuel amount Qp and the required injection fuel amount Qinj of the high-pressure pump 140, the high-pressure regulator estimated flow rate Qreg is calculated as in the following equation (step S203), and the processing flow of FIG.

  Qreg = Qp-Qinj

Next, the abnormality detection process (step S107) in FIG. 7 will be described with reference to FIG.
First, the abnormality detection means in the ECU 150 initializes the abnormality detection flag f_fail to “0” (step S301).

Subsequently, when the engine is stopped and when the fuel pressure Fp is not stable and the rotation is not stable, it is determined whether or not the engine rotational speed Ne exceeds 500 [r / min] in order to prohibit the abnormality detection processing (step S302).
If the condition is not satisfied in step S302 and it is determined that Ne ≦ 500 [r / min] (that is, NO), the abnormality detection process is not executed and the process flow of FIG. 9 is terminated.

On the other hand, if it is determined in step S302 that Ne> 500 [r / min] (that is, YES), the abnormality determination value Fp_fail is calculated using the map data map2 (Qreg) using the high-pressure regulator estimated flow rate Qreg as a parameter. (Step S303).
At this time, as shown in FIG. 4, the map data map2 (Qreg) is set based on the characteristics of the high pressure regulator 141 while securing a margin such as a variation of the high pressure regulator 141 and the fuel pressure sensor 163. desirable.

Next, it is determined whether or not the fuel pressure Fp is smaller than the abnormality determination value Fp_fail (step S304). If the condition is not satisfied and it is determined that Fp ≧ Fp_fail (that is, NO), it is regarded as a normal state. The process flow of FIG. 9 is terminated.
On the other hand, if the condition is satisfied in step S304 and it is determined that Fp <Fp_fail (that is, YES), an abnormal state has been detected. Therefore, “1” is set to the abnormality detection flag f_fail (step S305). The process flow of 9 is terminated.

Next, processing for each 1 [msec] will be described with reference to FIG.
In FIG. 10, first, the detected value FP_r of the fuel pressure Fp repeatedly detected by the fuel pressure sensor 163 is accumulated as a fuel pressure integrated value FPsum (step S301).
Here, the fuel pressure integrated value FPsum is expressed by the following equation using the fuel pressure integrated value FPsum (i−1) up to the previous time and the current fuel pressure detected value FP_r.

  FPsum = FPsum (i−1) + FP_r

  Subsequently, the cumulative number C_FPsum of the fuel pressure detection value FP_r is incremented by “1” (step S302), and the processing flow of FIG.

In the above description, the abnormality determination value Fp_fail is set based on the characteristics of the fixed pressure type high pressure regulator 141. However, the present invention may be applied to a variable pressure type high pressure regulator that adjusts the flow rate by an electromagnetic valve.

  Further, for example, when foreign matter is caught in the valve 204 (see FIG. 3) portion of the high pressure regulator 141, the amount of leakage of the valve 204 increases, and the fuel pressure is likely to decrease in the low flow rate region of the high pressure regulator 141. Therefore, it is desirable to set the abnormality determination value Fp_fail in the low flow rate range low. Thereby, the abnormality detection by temporary foreign object biting can be prevented.

In the above description, the abnormality detection device of the fuel supply system includes the fuel injection valves 106a to 106d that inject fuel into each cylinder of the internal combustion engine 101, and the delivery pipe 162 that supplies pressurized fuel to the fuel injection valves 106a to 106d. A pump drive cam 146 driven by the internal combustion engine 101, a high pressure pump 140 driven by the pump drive cam 146 to discharge pressurized fuel to the delivery pipe 162, and a high pressure pump 140 provided downstream of the high pressure pump 140. A high pressure regulator 141 that adjusts the pressure of the fuel discharged from the fuel, and a fuel pressure sensor 163 that detects the fuel pressure Fp in the delivery pipe 162.

The ECU 150 also includes high pressure regulator flow rate estimating means for obtaining the high pressure regulator estimated flow rate Qreg, and abnormality detection means for detecting an abnormality in the fuel supply system.
The high pressure regulator flow rate estimation means in the ECU 150 is configured to calculate a discharge estimated fuel amount Qp of the high pressure pump 140 calculated based on the engine rotational speed Ne and a required injection fuel amount Qinj calculated based on the operating state of the internal combustion engine 101. The high pressure regulator estimated flow rate Qreg is obtained based on the fuel amount deviation (= Qp−Qinj).

The abnormality detection means in the ECU 150 detects an abnormality in the fuel supply system based on the high pressure regulator estimated flow rate Qreg and the fuel pressure Fp.
That is, the abnormality detection means determines that the fuel supply system is abnormal when the fuel pressure Fp is lower than the abnormality determination value Fp_fail calculated according to the high pressure regulator estimated flow rate Qreg.

Thereby, compared with the abnormality detection based only on the fuel pressure Fp, the characteristic change according to the flow rate of the high-pressure regulator 141 can be taken into consideration, and the abnormality can be detected with high accuracy.
Further, the abnormality determination value Fp_fail can be determined according to the set fuel pressure determined from the characteristics of the high pressure regulator 141, and the abnormality determination value Fp_fail can be set appropriately.
Further, the abnormality determination value Fp_fail is set to decrease as the high pressure regulator estimated flow rate Qreg decreases, so that the abnormality determination value Fp_fail is set low in the low flow rate region of the high pressure regulator 141 where the fuel pressure Fp decreases. Therefore, it is possible to prevent erroneous detection in a normal state.

In the above description, the value obtained by subtracting the required fuel injection amount Qinj from the estimated fuel discharge amount Qp of the high-pressure pump 140 is used as it is as the high-pressure regulator estimated flow rate Qreg , but the high-pressure regulator estimated flow rate Qreg is used in consideration of the response time of the fuel pressure Fp. Filter processing means may be added in the regulator flow rate estimation means.

In this case, the high-pressure regulator flow rate estimating means in the ECU 150 includes a filter processing means, and the filter processing means applies to the high-pressure regulator estimated flow rate Qreg so as to suppress a change in the abnormality determination value Fp_fail with respect to the high-pressure regulator estimated flow rate Qreg. Correction by filter processing is performed.
Further, the filter processing means performs filtering on the high-pressure regulator estimated flow rate Qreg so that the change to the increase side of the abnormality determination value Fp_fail is slower than the change to the decrease side of the abnormality determination value Fp_fail. Make corrections.

FIG. 11 is a timing chart showing the behavior of each parameter according to Reference Example 1 to which filter processing means is added, and is shown in comparison with the case of no filter (see thin line).
FIG. 11 shows the time change of each parameter when the estimated fuel amount Qp of the high pressure pump 140 is constant and suddenly changes from a high load state to a deceleration operation state (fuel cut state).

As described above, the abnormality determination value Fp_fail is calculated using the high-pressure regulator estimated flow rate Qreg.
Here, as shown in FIG. 11, when the injection amount Qcyl per stroke suddenly changes from the injection amount in the high load state to the fuel cut state, if there is no filtering means, the high pressure regulator estimated flow rate Qreg changes suddenly as indicated by a thin line.

  On the other hand, the fuel pressure Fp in the delivery pipe 162 increases at the time of transition from the high load state to the fuel cut, but due to the detection delay of the fuel pressure sensor 163, a response delay occurs in the increase timing as shown in FIG. To do.

That is, when there is no filter, the increase timing of the fuel pressure Fp is delayed with respect to the steep change of the high pressure regulator estimated flow rate Qreg, and the abnormality determination value Fp_fail changes before the change timing of the fuel pressure Fp. .
As a result, when the high pressure regulator estimated flow rate Qreg increases, if the filtering process for the high pressure regulator estimated flow rate Qreg is not executed, the abnormality determination value Fp_fail (following the thin line in FIG. 11) follows the fuel pressure Fp and the high pressure regulator estimated flow rate Qreg. Margin) (see the broken double-pointed arrow) is insufficient, and an abnormal state may be erroneously detected.

  However, it is possible to secure a margin between the fuel pressure Fp and the abnormality determination value Fp_fail as indicated by a thick line in FIG. 11 by correcting the high-pressure regulator estimated flow rate Qreg by filtering.

However, when the high-pressure regulator estimated flow rate Qreg decreases, conversely, the margin of the abnormality determination value Fp_fail increases, and the margin is decreased by applying too much correction in the filter processing.
Therefore, the filtering process corrects so that the change to the increase side of the high pressure regulator estimated flow rate Qreg and the abnormality determination value Fp_fail is delayed as compared to the change to the decrease side of the high pressure regulator estimated flow rate Qreg and the abnormality determination value Fp_fail. Is desirable.

FIG. 12 is a flowchart showing the calculation processing procedure of the high-pressure regulator estimated flow rate Qreg according to Reference Example 1. Steps S501 to S503 are the same processing as steps S201 to S203 described above (see FIG. 8). Since the other processing flows are the same as described above, description thereof is omitted here.

In FIG. 12, first, the high pressure regulator estimated flow rate Qreg_r before filter correction is calculated by the same arithmetic processing (steps S501 to S503) as described above.
That is, a value obtained by subtracting the required injection fuel amount Qinj from the estimated discharge fuel amount Qp of the high-pressure pump 140 is calculated as the high-pressure regulator estimated flow rate Qreg_r.

  Next, the value of the filter coefficient k_f is initialized to “0.5” (step S504), the previous high-pressure regulator estimated flow rate Qreg (i−1), and the high-pressure regulator estimation before filter correction calculated in step S503. The flow rate Qreg_r is compared, and it is determined whether or not Qreg_r> Qreg (i−1) (flow rate increasing side) (step S505).

If it is determined in step S505 that Qreg_r ≦ Qreg (that is, NO), the flow rate is decreasing, and the process proceeds to step S507 (described later) without changing the filter coefficient k_f.
On the other hand, if it is determined in step S505 that Qreg_r> Qreg (that is, YES), since the flow rate is increasing, the value of the filter coefficient k_f is increased to “0.9” so that the flow rate change becomes slow. Setting is made (step S506).

  Finally, using the filter coefficient k_f, the previous high-pressure regulator estimated flow rate Qreg (i−1), and the high-pressure regulator estimated flow rate Qreg_r before filter correction, the current correction is performed as shown in the following equation. The high pressure regulator estimated flow rate Qreg is obtained (step S507), and the processing flow of FIG.

  Qreg = k_f * Qreg (i-1) + (1-k_f) * Qreg_r

As described above, according to the reference example 1 , the high pressure regulator flow rate estimating means in the ECU 150 includes the filter processing means, and corrects the high pressure regulator estimated flow rate Qreg by the filter processing so that the change becomes small. Further, it is possible to suppress erroneous detection due to an increase delay (see FIG. 11) in the fuel pressure Fp.

  Further, the filter processing means performs filtering on the high-pressure regulator estimated flow rate Qreg so that the change to the increase side of the abnormality determination value Fp_fail is slower than the change to the decrease side of the abnormality determination value Fp_fail. Since the correction is performed, it is possible to appropriately secure a margin for the abnormality determination value Fp_fail obtained from the high-pressure regulator estimated flow rate Qreg.

In the above description, the high-pressure regulator estimated flow rate Qreg is corrected by filtering as it is. However, the high-pressure regulator estimated flow rate Qreg is divided into levels such as a low flow rate region, a middle flow rate region, and a high flow rate region. Delay processing by the filter processing means may be executed when the level changes.
In this case, at the time of the change to the high flow rate side, if the delay time is set longer than that at the time of the change to the low flow rate side, the same effect as described above can be obtained. Further, the abnormality determination value Fp_fail may be set according to the flow level.

Although not particularly mentioned in the above description, it is desirable to prohibit the abnormality detection processing of the fuel supply system by the abnormality detection means when the high pressure regulator estimated flow rate Qreg is less than the predetermined flow rate .
Hereinafter, a first embodiment of the present invention in which the abnormality detection process is prohibited under a predetermined condition will be described.

As described above, the set fuel pressure can be maintained in the region where the flow rate of the high pressure regulator 141 is less than a predetermined flow rate (for example, 1 [L / h]) due to the characteristics of the high pressure regulator 141 (see FIG. 4). Disappear.
Therefore, it is desirable to set a predetermined flow rate based on the characteristics of the high-pressure regulator 141 and prohibit detection of abnormality in the fuel supply system when the high-pressure regulator estimated flow rate Qreg is less than the predetermined flow rate.

  Therefore, in this case, the abnormality detection means in the ECU 150 prohibits execution of the abnormality detection process of the fuel supply system when the high-pressure regulator estimated flow rate Qreg is smaller than the predetermined flow rate.

The predetermined flow rate is determined based on a flow rate at which the high pressure regulator 141 cannot maintain a predetermined fuel pressure (for example, 7 [MPa]) set in advance in a normal state.
The abnormality detecting means includes predetermined flow rate correcting means for adding a correction amount to the predetermined flow rate, and the predetermined flow rate correcting means increases the correction amount as the estimated discharge fuel amount Qp of the high-pressure pump 140 increases. Yes.

Generally, as a condition when the high pressure regulator estimated flow rate Qreg is less than a predetermined flow rate, basically, the required injection fuel amount Qinj is increased (low temperature, high load).
Further, when attention is paid to the estimated discharge fuel amount Qp of the high-pressure pump 140 as a parameter when the required injection fuel amount Qinj is increased, there are an increase (high rotation) and a decrease (low rotation) when the estimated discharge fuel amount Qp is increased. It is done.

The estimated fuel amount Qp discharged from the high-pressure pump 140 is substantially proportional to the engine speed Ne, and the required injected fuel amount Qinj is proportional to the load.
Further, the high-pressure regulator estimated flow rate Qreg (= Qp−Qinj) decreases as the load becomes higher.

  On the other hand, since the estimated discharge fuel amount Qp and the required injection fuel amount Qinj include variations, the calculated high-pressure regulator estimated flow rate Qreg also includes errors due to variations. Further, the larger the values of the estimated discharge fuel amount Qp and the required injected fuel amount Qinj, the greater the influence of variation.

For example, when the estimated flow rate Qreg (= Qp−Qinj) of the high pressure regulator is 1 [L / h], the following two conditions (1) are given as combinations of the estimated fuel amount Qp and the required injected fuel amount Qinj: Consider (2).
(1) Qp = 50 [L / h] and Qinj = 49 [L / h]
(2) Qp = 5 [L / h] and Qinj = 4 [L / h]

  Here, assuming that each variation width of the estimated discharge fuel amount Qp and the required injection fuel amount Qinj is “± 10%”, in the case of the condition (1), each variation width of the estimated discharge fuel amount Qp and the required injection fuel amount Qinj is Since it is about 5 [L / h], the variation width of the high-pressure regulator estimated flow rate Qreg is about 10 [L / h] at the maximum.

  On the other hand, in the case of the condition (2), each variation width of the estimated discharge fuel amount Qp and the required injection fuel amount Qinj is about 0.5 [L / h], so the variation width of the high-pressure regulator estimated flow rate Qreg is the maximum. 1 [L / h] or so.

  As described above, as the estimated discharge fuel amount Qp of the high-pressure pump 140 increases, an error due to variations in the estimated high-pressure regulator flow rate Qreg increases, so the estimated discharge fuel amount Qp of the high-pressure pump 140 increases with respect to the predetermined flow rate. It is desirable to add a correction amount that increases with time.

FIG. 13 is a flowchart showing an abnormality detection processing procedure according to the first embodiment of the present invention. Steps S601, S602, S605 to S607 are the same as steps S301 to S305 described above (see FIG. 9). Since the other processing flows are the same as described above, description thereof is omitted here.

In FIG. 13, first, the abnormality detection flag f_fail is initially set to “0” (step S601), and it is determined whether or not the engine rotational speed Ne exceeds 500 [r / min] (step S602).
If it is determined in step S602 that Ne ≦ 500 [r / min] (that is, NO), the abnormality detection process is not executed and the process flow of FIG. 13 is terminated.

  On the other hand, if it is determined in step S602 that Ne> 500 [r / min] (that is, YES), abnormality detection is performed using the map data map3 (Qp) using the estimated fuel amount Qp of the high-pressure pump 140 as a parameter. A predetermined flow rate Qreg_low for determining prohibition is calculated (step S603).

  Subsequently, the high pressure regulator estimated flow rate Qreg is compared with the predetermined flow rate Qreg_low calculated in step S603, and the high pressure regulator estimated flow rate Qreg is sufficient to execute the abnormality detection process depending on whether Qreg ≧ Qreg_low. It is determined whether the flow rate is high (step S604).

  If the high-pressure regulator estimated flow rate Qreg is small and it is determined in step S604 that Qreg <Qreg_low (that is, NO), the prohibition condition of the abnormality detection process is satisfied, so the process of FIG. 13 is performed without executing the abnormality detection process. End the flow.

  On the other hand, if it is determined in step S604 that Qreg ≧ Qreg_low (that is, YES), the abnormality detection processing (steps S605 to S607) similar to the above-described steps S303 to S305 is executed, and the processing flow of FIG. To do.

As described above, according to the first embodiment of the present invention, the abnormality detection means in the ECU 150 prohibits the abnormality detection processing of the fuel supply system when the high pressure regulator estimated flow rate Qreg is smaller than the predetermined flow rate Qreg_low. It is possible to prevent erroneous detection of an abnormal state in a normal state.
Further, the predetermined flow rate Qreg_low is determined based on a flow rate at which the high pressure regulator 141 cannot maintain the fuel pressure set in advance in a normal state, and thus can be set to an optimum value that matches the characteristics of the high pressure regulator 141.
Further, the correction amount is added to the predetermined flow rate Qreg_low, and the correction amount is set to increase as the estimated fuel amount Qp of the high-pressure pump 140 increases, so that variations in the high-pressure pump 140 and the fuel injection amount with respect to the predetermined flow rate Qreg_low can be reduced. The influence can be suppressed.

In the first embodiment , the delay in the fuel pressure Fp (see FIG. 11) is not taken into account when the abnormality detection process is executed when the high pressure regulator estimated flow rate Qreg is equal to or higher than the predetermined flow rate Qreg_low. Similarly to the reference example 1 , in order to prevent erroneous detection due to the delay of the fuel pressure Fp, the high pressure regulator estimated flow rate Qreg may be filtered to add a delay function.
Further, in this case, it is desirable to execute the abnormality detection process after a predetermined time has elapsed since the high-pressure regulator estimated flow rate Qreg becomes equal to or higher than the predetermined flow rate Qreg_low.

In the first embodiment , the four-cylinder in-cylinder internal combustion engine has been described. However, the present invention is also applicable to an internal combustion engine having an arbitrary number of cylinders such as six cylinders.
Further, as the high pressure regulator 141, a fixed type in which the fuel pressure is set by adjusting the flow rate by the biasing force of the spring 205 (see FIG. 3) has been described as an example, but the present invention is not limited to this type. A variable high-pressure regulator that adjusts the flow rate by an electromagnetic valve may be used.

1 is a block configuration diagram schematically showing an abnormality detection device for a fuel supply system for an internal combustion engine according to Embodiment 1 of the present invention. FIG. 1 is a system diagram showing a fuel supply system applied to Embodiment 1 of the present invention. It is sectional drawing which shows the internal structure of the high voltage | pressure regulator applied to Embodiment 1 of this invention. It is explanatory drawing which shows the characteristic of the high voltage | pressure regulator applied to Embodiment 1 of this invention. It is explanatory drawing which shows the characteristic of the high pressure pump applied to Embodiment 1 of this invention. 4 is a timing chart showing temporal changes of parameters in an operating state in which acceleration / deceleration is performed in a four-cylinder direct injection internal combustion engine applied to Embodiment 1 of the present invention. It is a flowchart which shows the processing operation for every predetermined period which concerns on Embodiment 1 of this invention. It is a flowchart which shows the calculation process of the high voltage | pressure regulator estimated flow volume which concerns on Embodiment 1 of this invention. It is a flowchart which shows the abnormality detection process which concerns on Embodiment 1 of this invention. It is a flowchart which shows the arithmetic processing for every 1 [msec] which concerns on Embodiment 1 of this invention. 6 is a timing chart showing fuel pressure behavior when a high-pressure regulator estimated flow rate according to Reference Example 1 changes. 6 is a flowchart showing a calculation process of a high-pressure regulator estimated flow rate according to Reference Example 1 . It is a flowchart which shows the abnormality detection process which concerns on Embodiment 1 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 Internal combustion engine (engine), 106, 106a-106d Fuel injection valve, 110 Cam shaft, 112, 122 Sensor, 120 Crank shaft, 140 High pressure pump, 141 High pressure regulator, 146 Pump drive cam, 150 ECU (electronic control unit) , 160 Fuel tank, 161 Low pressure pump, 162 Delivery pipe, 163 Fuel pressure sensor.

Claims (4)

A fuel injection valve that individually injects fuel into each cylinder of the internal combustion engine;
A delivery pipe for supplying pressurized fuel to the fuel injection valve;
A pump drive cam driven by the internal combustion engine;
A high pressure pump driven by the pump drive cam to discharge pressurized fuel to the delivery pipe;
A high-pressure regulator that is provided downstream of the high-pressure pump and adjusts the pressure of fuel discharged from the high-pressure pump;
In the fuel supply system of the internal combustion engine, comprising a fuel pressure detection means for detecting fuel pressure in the delivery pipe,
High pressure regulator flow rate estimating means for obtaining a high pressure regulator estimated flow rate corresponding to the flow rate of the high pressure regulator;
An abnormality detecting means for detecting an abnormality of the fuel supply system,
The high-pressure regulator flow rate estimating means is a fuel amount between a discharge estimated fuel amount of the high-pressure pump calculated based on a rotational speed of the internal combustion engine and a required injection fuel amount calculated based on an operating state of the internal combustion engine. Using the deviation, find the high-pressure regulator estimated flow rate,
The abnormality detection means includes
The fuel pressure is compared with the abnormality determination value, which is lower than the fuel pressure set for the high pressure regulator and compared with the fuel pressure, which is set to decrease as the estimated flow rate of the high pressure regulator decreases. And determining that the fuel supply system is abnormal ,
When the estimated flow rate of the high pressure regulator is less than a predetermined flow rate that determines a region in which the set fuel pressure that is an adjustment target in a normal state cannot be maintained when the flow rate of the high pressure regulator decreases , the fuel supply An abnormality detection device for a fuel supply system for an internal combustion engine, wherein the abnormality detection of the system is prohibited. The high pressure regulator flow rate estimating means includes a filter processing means,
2. The internal combustion engine according to claim 1 , wherein the filter processing unit corrects the high-pressure regulator estimated flow rate by filter processing so as to suppress a change in the abnormality determination value with respect to the high-pressure regulator estimated flow rate. Abnormality detection device for engine fuel supply system. The filter processing means corrects the high-pressure regulator estimated flow rate by a filter process so that a change to the increase side of the abnormality determination value is slower than a change to the decrease side of the abnormality determination value. The abnormality detection device for a fuel supply system for an internal combustion engine according to claim 2 , wherein: The abnormality detection means includes predetermined flow rate correction means for adding a correction amount to the predetermined flow rate,
The fuel for an internal combustion engine according to any one of claims 1 to 3, wherein the predetermined flow rate correction means increases the correction amount as the estimated discharge fuel amount of the high-pressure pump increases. Supply system abnormality detection device.

Images