JP2004144037A - Operation control method of high pressure pump for common rail - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promptly remove air mixed in a low pressure fuel system of a high pressure pump device for a common rail. <P>SOLUTION: In the high pressure pump device 10 for a common rail, low pressure fuel supplied by a feed pump 11 is regulated by a regulation valve 14 and fed to a plunger 12 so that high pressure fuel is obtained and supplied to the common rail. Based on a rail pressure signal PA from a rail pressure sensor 31 and a revolving speed signal Ne, when it is determined that the rail pressure PA does not reach a predetermined value PO in a certain period of time T1 at the time of cranking, the cranking is carried out under such a condition that the regulation valve 14 is fully closed, thereby removing the air mixed in the low pressure fuel system. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an operation control method for a high pressure pump for a common rail.
[0002]
[Prior art]
The fuel in the fuel tank is converted to high-pressure fuel using a high-pressure pump, and the high-pressure fuel is stored in a common rail. 2. Description of the Related Art A common rail system configured to inject and supply air to a vehicle is known.
[0003]
A typical example of a conventional common rail high pressure pump system is shown in FIG. In the high-pressure pump system 1 shown in FIG. 4, the fuel F in the fuel tank 2 is supplied to the high-pressure pump device 10 by the supply pipe 4 provided with the filter 3, and the excess fuel in the high-pressure pump device 10 passes through the overflow pipe 5. And returned to the fuel tank 2.
[0004]
The high-pressure pump device 10 is configured to suck up the fuel F in the fuel tank 2 via the supply pipe 4 by the feed pump 11 and supply the fuel F to the plunger 12. Therefore, an oil supply passage 13 is provided between the feed pump 11 and the plunger 12, and a metering valve 14 and a one-way valve 15 are provided in the oil supply passage 13 as shown in the figure. One end of the overflow oil passage 5 is connected to a feed oil passage 13 between the feed pump 11 and the metering valve 14 via a one-way valve 16, and the outlet side of the metering valve 14 is connected to the feed pump. The inlet 11 is connected to a return oil passage 18 provided with a zero delivery orifice 17.
[0005]
Since the high-pressure pump device 10 is configured as described above, the fuel F sucked up by the feed pump 11 is sent to the plunger 12 by the amount metered by the metering valve 14, and is pressurized here. The high-pressure fuel is sent to a common rail (not shown) via a high-pressure fuel oil passage 20 provided with a one-way valve 19. Here, the fuel F surplus in the metering by the metering valve 14 is returned to the fuel tank 2 via the overflow oil passage 5. Although the metering valve 14 has a fuel leak even if the metering is adjusted to zero, the leaked fuel has no pressure until the one-way valve 15 is opened and the feed pump passes through the return oil passage 18. It is returned to eleven.
[0006]
[Problems to be solved by the invention]
Since the high-pressure pump system for the common rail is configured and operates as described above, when air enters the low-pressure fuel piping system due to lack of gas, replacement of a filter, or other reasons, a part of the air flows from the plunger 12 to the common rail. However, when air enters the return oil passage 18 provided for the purpose of ensuring zero pumping performance, the air appears in the output of the metering valve 14 by the feed pump 11 and enters the return oil passage 18 again. Fall into. As a result, air continues to circulate in the above-described path during cranking, and the feed pump 11 cannot suck up fuel from the fuel tank 2 and cannot pump high-pressure fuel, thereby hindering the start of the internal combustion engine. There are cases.
[0007]
An object of the present invention is to provide an operation control method for a high pressure pump for a common rail which can quickly remove the mixed air from the low pressure fuel system when air is mixed in the low pressure fuel system of the high pressure pump for the common rail. Is to do.
[0008]
[Means for Solving the Problems]
According to the present invention, there is provided, according to the present invention, an operation control of a high pressure pump for a common rail, in which low pressure fuel fed by a feed pump is metered by a metering valve and sent to a plunger to obtain high pressure fuel. A method for determining whether or not the common rail pressure has reached a predetermined value within a predetermined time at the time of cranking, and if the common rail pressure has not reached the predetermined value within the predetermined time, the metering valve is turned on. An operation control method for a high pressure pump for a common rail, characterized in that cranking is performed in a fully closed state, is proposed.
[0009]
To determine whether the common rail pressure has reached a predetermined value within a predetermined time during cranking, check the actual rail pressure after the cranking operation has continued for a predetermined time, and check that the actual rail pressure has reached a predetermined target rail pressure. It is possible to determine whether or not the metering valve is fully closed when the actual rail pressure has not reached the predetermined target rail pressure. This determination process can be realized by data processing by a microcomputer.
[0010]
In addition, when it is determined that the actual rail pressure has not reached the predetermined target rail pressure, the operation of fully closing the metering valve may be manually performed by an operator.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1 is a system block diagram showing an example of an embodiment of the present invention. 1, 1 is a high-pressure pump system having the same configuration as the high-pressure pump system shown in FIG. 4, 30 is a common rail, 31 is a rail pressure sensor for detecting the pressure of high-pressure fuel in the common rail 30, and 32 is a microcomputer. And a central processing unit (CPU) 33 and a memory 34.
[0013]
The control unit 32 is configured to electronically control the operation of the high-pressure pump 10 based on a rail pressure signal PA output from the rail pressure sensor 31 and a rotation speed signal Ne from an engine rotation sensor (not shown). . The operation control of the high-pressure pump device 10 is performed by causing the CPU 33 to execute an operation control program stored in the memory 34.
[0014]
2 and 3 are flowcharts showing an operation control program. Hereinafter, operation control of the high-pressure pump device 10 will be described with reference to FIG.
[0015]
FIG. 2 is a flowchart showing the main control program. When the main control program is started, a start-time adjusting valve control process is executed in step 41, whereby control for air bleeding at the time of start is performed.
[0016]
FIG. 3 is a detailed flowchart of step 41. Hereinafter, the details of the startup control valve control process in step 41 will be described with reference to FIG.
[0017]
First, initialization is performed in step 51, and data is read in step 52. Here, the values of the rail pressure signal PA and the rotation speed signal Ne are read and stored in the memory 34. In the following description, the read values may be referred to as rail pressure PA and rotation speed Ne.
[0018]
In the next step 53, the metering valve 14 is set to the opening required for starting the internal combustion engine, and the routine proceeds to step 54.
[0019]
In step 54, it is determined whether or not the internal combustion engine is cranking based on the rotation speed Ne. Specifically, the determination is made based on whether the rotation speed Ne is within a predetermined rotation speed range (NA to NB). Here, the values of NA and NB can be set to appropriate values necessary for determining cranking. If NA <Ne <NB, it is determined that the internal combustion engine is not in the cranking state, the determination signal in step 54 is NO, and the routine proceeds to step 42 of the main control program.
[0020]
On the other hand, if NA <Ne <NB in step 54, it is determined that the internal combustion engine is cranking. In step 55, it is determined whether or not a predetermined time T1 has elapsed since the determination result in step 54 became YES. Until the predetermined time T1 has elapsed, the determination result of step 55 is NO, and step 55 is repeatedly executed. When the predetermined time T1 has elapsed, the determination result of step 55 becomes YES and the process proceeds to step 56.
[0021]
In step 56, it is determined whether or not the detected rail pressure PA at that time is higher than the pumping state determination pressure PO. If PA> PO, it is determined that the high-pressure pump device 10 is operating normally, and the determination result is YES, and the routine proceeds to step 42. On the other hand, when PA ≦ PO, since the rail pressure has not reached the target value even after the lapse of the predetermined time T1, it is determined that the high-pressure pump device 10 is not operating normally, and the determination result is NO, Step 57 is entered.
[0022]
In step 57, the metering valve 14 is fully closed for a predetermined time T2. If the metering valve 14 is fully closed, the fuel supplied from the feed pump 11 is almost returned to the fuel tank 2 via the overflow oil passage 5. As a result, the air in the fuel in the return oil passage 18 is gradually discharged from the overflow oil passage 5 to the fuel tank 2 and returned to the atmosphere. Then, since the fuel containing no air is supplied from the fuel tank 2 to the feed pump 11, the air mixed in the low-pressure fuel system of the high-pressure pump device 10 eventually closes the metering valve 14 fully. Can be removed.
[0023]
In the next step 58, it is determined whether or not a predetermined time T3 has elapsed since the execution of step 54 was completed. If the predetermined time T3 has not elapsed, the determination result is NO and the process returns to step 53, and the steps after step 53 are executed again as described above.
[0024]
If it is determined in step 58 that the predetermined time T3 has elapsed, the determination result in step 58 is YES, and the process proceeds to step 42.
[0025]
Returning to FIG. 2, it is determined in step 42 whether or not the air bleeding has been completed. If it is determined that the air bleeding has been completed, the result of the determination in step 42 becomes YES and the process proceeds to step 43.
[0026]
In step 43, the high-pressure pump device 10 executes a high-pressure pump operation control (normal operation control) for setting the rail pressure to a predetermined value, and ends the execution of the present control program.
[0027]
On the other hand, if the decision result in the step 42 is NO, the process proceeds to a step 44, where the operation of the high-pressure pump device 10 is stopped, and the execution of this control program is ended.
[0028]
Since the high-pressure pump device 10 is controlled by the control unit 32 as described above, air is mixed into the low-pressure fuel system of the high-pressure pump device 10 for some reason, so that the rail pressure reaches the required target value. If a malfunction such as not rising to the maximum occurs, this is determined by determining the cranking operation based on the rotation speed of the internal combustion engine (steps 54 and 55) and determining the rail pressure based on the actual rail pressure information from the rail pressure sensor 31. A determination is made based on the suitability determination (step 56), and the air mixed into the low-pressure fuel system is evacuated by fully closing the metering valve 14, so that air is mixed into the low-pressure fuel system. Even in this case, the internal combustion engine can be reliably started.
[0029]
As can be understood from the above description, it is possible to determine the malfunction of the high-pressure pump device 10 and control the fully-closed control of the metering valve 14 by changing the software in the control unit 32 without increasing the cost substantially. The control according to the present invention can be performed, whereby the number of man-hours for manual priming by the hand primer after running out of gas, replacing the filter, and the like can be reduced.
[0030]
Note that, in the above embodiment, when the rail pressure rise failure is determined, the fully closing operation of the metering valve 14 for bleeding air is automatically executed. However, the present invention is not limited to this configuration. On the other hand, if the determination result in the step 41 is NO, the result is stopped to be displayed to the operator, a switch for completely closing the metering valve 14 is provided, and the display result is viewed by the operator. The on / off operation of the switch may be performed at the discretion of the operator.
[0031]
【The invention's effect】
According to the present invention, as described above, when air enters the low-pressure side of the high-pressure pump for a common rail and a problem that causes a failure in increasing the rail pressure occurs, the problem can be corrected extremely simply and at low cost. Since it can be returned to the state, it can greatly contribute to providing a highly reliable common rail system that can reliably start the internal combustion engine.
[Brief description of the drawings]
FIG. 1 is a system block diagram showing an example of an embodiment of the present invention.
FIG. 2 is a flowchart showing a main control program of an operation control program executed by the control unit of FIG. 1;
FIG. 3 is a detailed flowchart of a startup control valve control processing step of a main control program shown in FIG. 2;
FIG. 4 is a system configuration diagram of a conventional common rail high-pressure pump system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 High-pressure pump system 2 Fuel tank F Fuel 3 Filter 4 Supply pipe 10 High-pressure pump device 5 Overflow oil passage 11 Feed pump 12 Plunger 13 Feeding oil passage 14 Metering valves 15, 16 One-way valve 17 Zero delivery orifice 18 Return oil passage 30 common rail 31 rail pressure sensor 32 control unit 33 central processing unit (CPU)
34 memory

Claims (1)

An operation control method for a high pressure pump for a common rail, wherein low pressure fuel supplied by a feed pump is metered by a metering valve and sent to a plunger to obtain high pressure fuel,
At the time of cranking, it is determined whether or not the common rail pressure has reached a predetermined value within a predetermined time, and if the common rail pressure has not reached the predetermined value within the predetermined time, the metering valve is fully closed to close. An operation control method for a high pressure pump for a common rail, wherein ranking is performed.

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