JP3932666B2 - Fuel injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device for an internal combustion engine provided with a supercharger, and more particularly to a fuel injection device provided with a spill valve that opens during the fuel pumping from a pump chamber to release fuel.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been used a fuel injection device that controls the fuel injection amount by controlling the opening and closing of a spill valve that opens in the course of pumping fuel from a pump chamber that expands and contracts due to reciprocating movement of a plunger. In such a fuel injection device, when the spill valve is in a closed state, the fuel injection amount cannot be controlled, and an overrun state is caused.
[0003]
Therefore, when the number of revolutions of the internal combustion engine is detected and the number of revolutions indicates an overrun state, the operation is stopped by closing the intake throttle valve that is opened and closed according to the accelerator opening.
[0004]
[Problems to be solved by the invention]
However, in such a conventional system, the operation of the internal combustion engine is stopped after the actual overrun state, so that the internal combustion engine may be damaged, and there is a problem in ensuring the safety of the operation. .
[0005]
An object of the present invention is to provide a fuel injection device capable of detecting a spill valve failure before an internal combustion engine overruns.
[0006]
[Means for Solving the Problems]
In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
A supply flow path for supplying fuel to a pump chamber that expands and contracts by reciprocation of a plunger, and a spill valve that allows fuel to escape from the pump chamber,
In the fuel injection device that controls the opening and closing of the spill valve according to the injection amount command value calculated based on the operating conditions including the rotational speed of the internal combustion engine with a supercharger and the accelerator opening,
A supercharging pressure sensor that detects the supercharging pressure pressurized by the supercharger;
A calculating means for calculating a supercharging pressure reference value from the rotational speed of the supercharged internal combustion engine and the injection amount command value;
Failure determination means is provided for comparing the supercharging pressure detected by the supercharging pressure sensor with the supercharging pressure reference value calculated by the calculating means to determine whether the spill valve is closed abnormally. This is a fuel injection device characterized by the following.
[0007]
In addition, it may be configured to include a notifying means for notifying the abnormality when the failure determining means determines that an abnormality has occurred. Further, the failure determination means may close the supply flow path by closing a fuel cutoff valve interposed in the supply flow path when there is an abnormality. Alternatively, the failure determination means may close an intake throttle valve provided in the intake passage of the internal combustion engine when it is abnormal.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, 1 is an injection pump, and the injection pump 1 includes a plunger 2 supported so as to be reciprocally movable. A cam plate 4 is attached to the plunger 2, and a cam roller 6 is provided facing the cam plate 4. When the cam plate 4 is rotated with the rotation of the internal combustion engine body 20, the cam plate 4 is reciprocated together with the plunger 2.
[0009]
The volume of the pump chamber 8 is expanded and contracted by the reciprocating movement of the plunger 2, and the fuel in the pump chamber 8 is pressurized and supplied to the fuel injection valve 10. A supply passage 12 and a spill passage 14 are connected to the pump chamber 8, and the supply passage 12 and the spill passage 14 communicate with a fuel chamber (not shown).
[0010]
A fuel cutoff valve 16 is interposed in the supply passage 12, and a spill valve 18 is interposed in the spill passage 14. In the present embodiment, the spill valve 18 is configured to close when an excitation signal is input and to open by a biasing force of a spring (not shown).
[0011]
The fuel supplied to the fuel injection valve 10 is injected into a combustion chamber (not shown) of the internal combustion engine body 20. The internal combustion engine main body 20 includes a supercharger 22, and the supercharger 22 is a well-known one that boosts the intake air from the intake pipe 24 using the exhaust discharged from the exhaust pipe 26.
[0012]
A supercharging pressure sensor 28 for detecting the supercharging pressure of the intake air boosted by the supercharger 22 is provided, and a rotational speed sensor 30 for detecting the rotational speed of the internal combustion engine body 20 is provided. Further, an accelerator sensor 32 that detects the opening of an accelerator pedal (not shown) operated by the driver is also provided.
[0013]
The supercharging pressure sensor 28, the rotation speed sensor 30, and the accelerator sensor 32 are connected to an electronic control circuit 50. The electronic control circuit 50 is configured with a well-known CPU 52, ROM 54, and RAM 56 as the center of a logic operation circuit. An input / output circuit 58 for performing input / output with the outside is connected to each other via a common bus 60.
[0014]
The CPU 52 inputs signals from the supercharging pressure sensor 28, the rotation speed sensor 30, and the accelerator sensor 32 via the input / output circuit 58. On the other hand, based on these signals, data in the ROM 54 and RAM 56, and a control program stored in advance, the CPU 52 calculates a fuel injection amount and the like according to the operating state of the internal combustion engine body 20, and inputs based on the calculated values. A drive signal is output to the drive circuit 62 via the output circuit 58. The drive circuit 62 receives the drive signal and outputs an excitation signal to the fuel cutoff valve 16 and the spill valve 18.
[0015]
Next, the opening / closing control process performed in the electronic control circuit 50 will be described with reference to the flowchart of FIG.
First, when the operation of the internal combustion engine body 20 is started, an injection amount command value is determined based on a map (not shown) or the like based on the rotational speed NE detected by the rotational speed sensor 30 and the accelerator opening ACCPF detected by the accelerator sensor 32. QFIN is calculated (step 100).
[0016]
Next, the closing timing QPANGF of the spill valve 18 is calculated from the rotational speed NE detected by the rotational speed sensor 30 and the previous valve opening timing QANGF (step 110). Then, the valve opening timing QANGF of the spill valve 18 is calculated from the rotational speed NE detected by the rotational speed sensor 30 and the injection amount command value QFIN (step 120). Subsequently, a drive signal corresponding to the calculated valve closing timing QPANGF and valve opening timing QANGF is output to the drive circuit 62 (step 130). The drive circuit 62 receives this drive signal and outputs an excitation signal to the spill valve 18.
[0017]
In the present embodiment, as shown in FIG. 4, after the pump chamber 8 is compressed, the supply flow path 12 is communicated by the rotation of the plunger 2 and the slit at the tip of the plunger 2. The fuel is sucked from the supply channel 12 and the spill channel 14. And after the pump chamber 8 is expanded, the supply flow path 12 is interrupted | blocked.
[0018]
The spill valve 18 is closed at a valve closing timing QPANGF at which the plunger 2 starts to compress the pump chamber 8, whereby the fuel compressed from the pump chamber 8 is supplied to the fuel injection valve 10. Further, when the valve opening timing QANGF is reached, the spill valve 18 is opened, and the fuel is returned from the pump chamber 8 through the spill passage 14 to the fuel chamber. Therefore, fuel is injected from the fuel injection valve 10 during the period between the valve closing timing QPANGF and the valve opening timing QANGF.
[0019]
While the opening / closing control process is repeatedly executed, the failure time control process shown in FIG. 3 is repeatedly executed.
In this failure time control process, first, the supercharging pressure reference value PIMBASE is calculated based on the rotational speed NE detected by the rotational speed sensor 30 and the injection amount command value QFIN (step 200). As indicated by the solid line in FIG. 5, when the spill valve 18 is operating normally, the supercharging pressure PIM increases in accordance with the injection amount command value QFIN. Further, as shown in FIG. 6, the supercharging pressure PIM and the rotational speed NE have a certain relationship according to the magnitude of the load.
[0020]
The supercharging pressure reference value PIMBASE is created and stored in advance based on the rotational speed NE and the injection amount command value QFIN through experiments or the like. A supercharging pressure reference value PIMBASE is calculated from this map based on the rotational speed NE and the injection amount command value QFIN. If the spill valve 18 is closed and fails, the supercharging pressure becomes constant at a high level. A predetermined value Δα is added to the relationship between the supercharging pressure PIM and the injection amount command value QFIN when the spill valve 18 is operating normally to obtain a supercharging pressure reference value PIMBASE.
[0021]
Next, it is determined whether or not the supercharging pressure PIM detected by the supercharging pressure sensor 28 exceeds the supercharging pressure reference value PIMBASE (step 210). When the supercharging pressure PIM is equal to or lower than the supercharging pressure reference value PIMBASE, it is determined that the pressure is normal, and the present control process is temporarily terminated.
[0022]
On the other hand, when the supercharging pressure PIM exceeds the supercharging pressure reference value PIMBASE, the control of the spill valve 18 is stopped (step 220), and the output of the excitation signal to the fuel cutoff valve 16 is stopped to stop the fuel cutoff valve. 16 is closed and the supply flow path 12 is shut off (step 230). As a result, the operation of the internal combustion engine body 20 is stopped.
[0023]
Then, in order to notify the driver that the spill valve 18 has failed, notification such as turning on the failure lamp 64 is performed (step 240). Instead of closing the fuel cutoff valve 16, an intake throttle valve (not shown) provided in the intake passage may be closed to stop the operation of the internal combustion engine body 20. Alternatively, the operation may be stopped by closing the fuel cutoff valve 16 and closing the intake throttle valve.
[0024]
When the spill valve 18 breaks down and closes, the spill valve 18 does not open even when the valve opening timing QANGF is reached, so that pressurized fuel is supplied from the pump chamber 8 to the fuel injection valve 10. Fuel is injected. Accordingly, the rotation of the internal combustion engine body 20 is increased and the rotation speed is increased. As a result, the supercharging pressure of the intake air boosted by the supercharger 22 increases, and this supercharging pressure PIM is detected by the supercharging pressure sensor 28.
[0025]
Therefore, when the spill valve 18 fails in the closed state, the supercharging pressure PIM increases, and when the supercharging pressure PIM exceeds the supercharging pressure reference value PIMBASE, it is determined that the spill valve 18 has failed in the closed state. To do. Then, the fuel cutoff valve 16 is closed to shut off the fuel supply to the pump chamber 8.
[0026]
In the internal combustion engine provided with the supercharger 22, when the spill valve 18 is operating normally, the supercharging pressure PIM increases according to the injection amount command value QFIN. If a failure occurs with the spill valve 18 closed, the rotation increases and the supercharging pressure PIM becomes a high level. Therefore, it is possible to quickly detect that the spill valve 18 has failed before overrun.
[0027]
In the present embodiment, the execution of the process at step 200 serves as a calculation means, and the execution of the processes at steps 210 and 230 serves as a failure determination means. Moreover, execution of the process of the failure lamp 64 and step 240 serves as a notification means.
The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.
[0028]
【The invention's effect】
As described in detail above, when the fuel injection device of the present invention malfunctions in a state where the spill valve is closed, the rotation rises and the supercharging pressure becomes a high level. There is an effect that a failure can be detected.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a fuel injection device as one embodiment of the present invention.
FIG. 2 is a flowchart showing an example of an open / close control process performed by the electronic control circuit of the present embodiment.
FIG. 3 is a flowchart showing an example of a failure time control process performed by the electronic control circuit of the present embodiment.
FIG. 4 is a timing chart showing opening / closing timings of a spill valve and a supply flow path according to the present embodiment.
FIG. 5 is a graph showing a relationship between a supercharging pressure and an injection amount command value according to the present embodiment.
FIG. 6 is a graph showing the relationship between the supercharging pressure and the rotational speed of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Injection pump 2 ... Plunger 8 ... Pump chamber 10 ... Fuel injection valve 12 ... Supply flow path 14 ... Spill flow path 16 ... Fuel cutoff valve 18 ... Spill valve 20 ... Internal combustion engine main body 22 ... Supercharger 28 ... Supercharging pressure Sensor 30 ... Rotation speed sensor 32 ... Accelerator sensor 50 ... Electronic control circuit

Claims (4)

A supply flow path for supplying fuel to a pump chamber that expands and contracts by reciprocating movement of the plunger, and a spill valve that allows fuel to escape from the pump chamber,
In the fuel injection device that controls the opening and closing of the spill valve according to the injection amount command value calculated based on the operating condition including the rotational speed of the internal combustion engine with a supercharger and the accelerator opening,
A supercharging pressure sensor that detects the supercharging pressure pressurized by the supercharger;
A calculating means for calculating a supercharging pressure reference value from the rotational speed of the supercharged internal combustion engine and the injection amount command value;
Failure determination means is provided for comparing the supercharging pressure detected by the supercharging pressure sensor with the supercharging pressure reference value calculated by the calculating means to determine whether the spill valve is closed abnormally. A fuel injection device characterized by the above. 2. The fuel injection device according to claim 1, further comprising an informing means for informing the abnormality when the failure judging means judges that the abnormality is present. 3. The fuel according to claim 1, wherein the failure determination unit closes a fuel cutoff valve interposed in the supply flow path to shut off the supply flow path when there is an abnormality. Injection device. 4. The fuel injection device according to claim 1, wherein the failure determination means closes an intake throttle valve provided in an intake passage of the internal combustion engine when it is abnormal.

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