JP2015178804A - Common rail and fuel injection device using the common rail - Google Patents

Abstract

PROBLEM TO BE SOLVED: To alleviate a burden of work for making individual control devices store flow rate characteristics at each branch flow passage in individual common rails.SOLUTION: A common rail 3 comprises a pressure accumulation chamber which pressure-accumulates fuel at high pressure, and a branch flow passage which is branched from the pressure accumulation chamber toward each cylinder in an internal combustion engine, and in which an orifice is formed. The common rail distributes and supplies the high-pressure fuel to an injector which is mounted to each cylinder via the branch flow passage. Furthermore, a storage medium 30 for storing a flow rate characteristic having a correlation between the fuel pressure of the pressure accumulation chamber and a fuel flow rate which passes through the branch flow passage at each branch flow passage is added to the common rail. By this constitution, the flow rate characteristic at each branch flow passage in each of the individual common rails 3 can be exactly and easily stored at individual control devices 6 or the like by reading the storage medium 30, and a burden of a worker can be alleviated.

Description

  The present invention mainly relates to a common rail.

2. Description of the Related Art Conventionally, a common rail in which an orifice is provided for each branch flow path is known in order to prevent the pressure in an accumulator from pulsating with fuel injection from an injector.
However, there is a difference in the cross-sectional area and shape of the flow path due to the processing accuracy of the orifices between the branch flow paths. Difference). The flow rate characteristic difference for each branch flow path becomes a flow rate difference for each branch flow path, resulting in a difference in the fuel injection amount of each cylinder.

  Here, in order to suppress the difference in the fuel injection amount between the cylinders, it is conceivable that the injector is driven and controlled by the control device based on the flow rate characteristic of each branch flow path. However, in this case, the flow characteristics of each branch flow path in each common rail must be stored in advance in each control device. For this reason, it is necessary to definitely store all the flow characteristics for each branch flow path in each common rail in each control device, which imposes a considerable burden on the operator.

The following configuration is disclosed as a storage medium attached to a main body or the like.
For example, Patent Document 1 discloses a configuration in which a storage medium storing individual information of each injector is attached to each injector or the like.
Patent Document 2 discloses a configuration in which a storage medium storing individual information of each rail pressure sensor for detecting the fuel pressure in the common rail accumulator is attached to each sensor or the like.
However, in these configurations, the flow characteristics for each branch flow path in each common rail are not stored, and the burden of the above work cannot be reduced.

  Further, in order to suppress the difference in the fuel injection amount between the cylinders, Patent Document 3 discloses a configuration that measures the exhaust temperature of each cylinder and prevents variations in the fuel injection amount between the cylinders. Since a temperature sensor is required for each cylinder and cost increases cannot be avoided, it is difficult to actively adopt them.

JP 2002-276503 A JP 2009-114922 A JP 2004-76624 A

  The present invention has been made to solve the above-described problems, and its object is to reduce the burden on the operator who stores the flow rate characteristics of each branch flow path in each common rail in each control device. It is in.

According to the present invention, the common rail includes a pressure accumulating chamber for accumulating fuel at a high pressure, and a branch passage that branches from the accumulating chamber to each cylinder of the internal combustion engine and is provided with an orifice. .
Then, high-pressure fuel is distributed and supplied to the injectors mounted on each cylinder through this branch flow path.
In addition, a storage medium is provided that stores, for each branch flow path, a flow rate characteristic that is a correlation between the fuel pressure in the pressure accumulating chamber and the fuel flow rate that passes through the branch flow path.

  As a result, by reading the storage medium, it is possible to accurately and simply store the flow characteristics for each branch flow path in each common rail in each control device and the like, thereby reducing the burden on the operator.

1 is an overall view of a fuel injection device (Example). It is explanatory drawing of a common rail (Example). It is explanatory drawing about the flow volume characteristic for every branch flow path (Example). It is explanatory drawing of a storage medium (Example). It is a flowchart which shows the whole control method outline (Example). It is a flowchart of the control method which absorbs the flow volume characteristic difference for every branch flow path (Example). It is explanatory drawing of the specific example of the control method which absorbs the flow volume characteristic difference for every branch flow path (Example). It is explanatory drawing about the flow volume characteristic for every branch flow path (modification).

  Hereinafter, modes for carrying out the invention will be described based on examples.

  As shown in FIG. 1, the fuel injection device 1 injects fuel into each cylinder of an internal combustion engine 2 (for example, a diesel engine), and includes a common rail 3, an injector 4, a supply pump 5, an ECU 6 (control device), It consists of EDU7 (drive device) and the like.

  The common rail 3 is a pressure accumulation container for accumulating high-pressure fuel supplied to the injector 4, and a discharge port of a supply pump 5 that pumps high-pressure fuel through a high-pressure pump pipe 8 so that a common rail pressure corresponding to the fuel pressure is accumulated. And a plurality of injector pipes 9 for supplying high-pressure fuel to each injector 4.

  A pressure limiter 12 is attached to a relief pipe 11 that returns fuel from the common rail 3 to the fuel tank 10. The pressure limiter 12 is a pressure safety valve, and is opened when the common rail pressure in the common rail 3 exceeds the limit set pressure, and suppresses the common rail pressure of the common rail 3 below the limit set pressure.

  The common rail 3 is provided with a pressure reducing valve 13. The pressure reducing valve 13 is opened by a valve opening instruction signal from the ECU 6 to rapidly reduce the common rail pressure via the relief pipe 11. Thus, by mounting the pressure reducing valve 13 on the common rail 3, the ECU 6 can quickly control the common rail pressure to a pressure corresponding to the operating state of the internal combustion engine. In addition, as shown in FIG. 2, there is a common rail of a model in which the pressure reducing valve 13 is not mounted. FIG. 2 is a diagram for explaining the common rail 3, and there are portions that do not coincide with the common rail 3 in the configuration of FIG. 1.

The injector 4 is mounted in each cylinder of the internal combustion engine 2 and supplies fuel into each cylinder. The injector 4 is connected to the downstream ends of a plurality of injector pipes 9 branched from the common rail 3 and is accumulated in the common rail 3. In addition, a fuel injection nozzle that injects the high-pressure fuel into each cylinder and an electromagnetic valve that performs lift control of the needle accommodated in the fuel injection nozzle are mounted.
The fuel leaking from the injector 4 is also returned to the fuel tank 10 via the relief pipe 11.

The supply pump 5 is a high-pressure fuel pump that pumps high-pressure fuel to the common rail 3, a feed pump (for example, a trochoid pump) that sucks the fuel in the fuel tank 10 into the supply pump 5 through the filter 15, and this feed A high-pressure pump (for example, constituted by a plurality of plunger pumps) that compresses the fuel sucked up by the pump to a high pressure, and the feed pump and the high-pressure pump are driven by a common camshaft 16. is there.
The camshaft 16 is rotationally driven by the internal combustion engine 2.

  In the supply pump 5, an SCV 17 (suction metering valve) for adjusting the degree of opening of the fuel flow path is mounted in a fuel flow path for introducing fuel into the pressurizing chamber of the high pressure pump. The SCV 17 is a valve that is controlled by a pump drive signal from the ECU 6 to adjust the amount of fuel sucked into the pressurizing chamber and to change the amount of fuel to be pumped to the common rail 3. The common rail pressure is adjusted by adjusting the amount of fuel discharged. That is, the ECU 6 controls the SCV 17 to control the common rail pressure to a pressure corresponding to the operating state of the internal combustion engine 2.

The ECU 6 includes a CPU that performs control processing, arithmetic processing, and the like, a storage device that stores various programs and data (nonvolatile memory such as ROM, volatile memory such as RAM), an input circuit, an output circuit, a power supply circuit, and the like. A microcomputer having a well-known structure is provided.
Various arithmetic processes are performed on the basis of the signals of the sensors read by the ECU 6 (signals according to the operating state of the internal combustion engine 2).
In addition to the rail pressure sensor 18 that detects the common rail pressure, the ECU 6 detects the accelerator opening that detects the accelerator opening, and the rotational speed of the internal combustion engine 2 as means for detecting the operating state of the internal combustion engine 2 and the like. Sensors such as a rotation speed sensor and a water temperature sensor for detecting the cooling water temperature of the internal combustion engine 2 are connected.

An example of a specific calculation in the ECU 6 will be described. The ECU 6 performs the drive control of the SCV 17 according to the operation state of the internal combustion engine 2 and the injector control system that performs the drive control of the injector 4 according to the operation state of the internal combustion engine 2. Control the rail pressure control system to be performed.
For each fuel injection, the injector control system calculates the injection mode, target injection amount, injection start timing, etc. based on the program stored in the ROM and the signals of the sensors read in the RAM, and the injector opening Generate valve signals and so on.
The rail pressure control system calculates the target rail pressure based on the program stored in the ROM and the sensor signals read into the RAM, and calculates the rail pressure calculated from the value of the rail pressure sensor 18 as the target rail. An SCV drive signal or the like for matching the pressure is generated.

The EDU 7 includes an injector drive circuit that applies a valve opening drive current to the electromagnetic valve of the injector 4 based on an injector valve opening signal given from the ECU 6.
Although FIG. 1 shows an example in which the pump drive circuit that supplies the drive current to the SCV 17 is arranged in the ECU 6, the pump drive circuit may be arranged in the EDU 7.
Moreover, it is good also as a structure which mounts EDU7 and ECU6 in the same case.

The configuration of the common rail 3 will be described with reference to FIG.
As described above, FIG. 2 is a diagram for explaining the common rail 3, and there is a portion that does not coincide with the common rail 3 in the configuration of FIG.
In the common rail 3, a pressure limiter 12, a rail pressure sensor 18, and the like are attached to a cylindrical rail body 20 that stores high-pressure fuel therein.

A pressure accumulating chamber 21 for accumulating fuel at a high pressure is formed inside the rail body 20.
Further, the common rail 3 branches from the pressure accumulating chamber 21 toward each cylinder of the internal combustion engine 2, and includes a branch passage 23 provided with an orifice 22, and high-pressure fuel is supplied through the branch passage 23. This is a well-known configuration for distributing and supplying to the injectors 4 mounted on each cylinder.

Here, each of the common rails 3 has a difference in flow path cross-sectional area and shape due to the machining accuracy of the orifices 22 between the branch flow paths 23, and the flow characteristics of each branch flow path 23 (the fuel in the accumulator 21). The correlation between the pressure and the flow rate of the fuel passing through the branch flow path 23 is different, and each has a unique characteristic as shown in FIG.
FIG. 3 shows the flow characteristics of different common rails 3 at a predetermined fuel pressure P1 within the operating pressure range.

Each of the common rails 3 is provided with a storage medium 30 that stores a flow rate characteristic for each branch channel 23 as shown in FIG.
Here, the storage medium 30 is a kind of two-dimensional QR code as shown in FIG. 4B (QR code is a registered trademark of DENSO WAVE INCORPORATED) or a bar code shown in FIG. 4C. is there.
Further, specific examples of the attachment include a method of directly performing laser printing on the rail main body 20 and a method of attaching a film on which the storage medium 30 is printed to the rail main body 20.

Then, as shown in FIG. 4D, the storage medium 30 is read by a code reader 31 and stored in a storage area (ROM or the like) of each ECU 6 combined with each common rail 3 using a controller 32 and a writing device 33. A flow rate characteristic for each branch flow path 23 is stored.
That is, the ECU 6 stores the flow rate characteristic for each branch flow path 23 by reading the storage medium 30 in advance.

Then, the ECU 6 drives and controls the injector 4 based on the flow rate characteristic for each branch flow path 23.
Here, a specific example of drive control of the injector 4 based on the flow rate characteristic for each branch flow path 23 will be described with reference to FIGS.
FIG. 5 shows the entire control, and FIG. 6 shows an example of a control process for absorbing the flow characteristic difference for each branch flow path 23.

As shown in FIG. 5, in S <b> 100, the ECU 6 determines whether or not the flow characteristic for each branch flow path 23 of the common rail 3 is stored. When the flow rate characteristic is stored in the ECU 6, the process proceeds to S200, and the process proceeds to normal injection control in S300.
When the flow rate characteristic is not stored in the ECU 6, the determination in S100 is repeated until the storage in the ECU 6 is performed.

In S <b> 200, control for absorbing the flow characteristic difference for each branch flow path 23 is performed.
In S300, a target injection amount is set for each injector 4 by the control process in S200, and normal injection control is performed based on the target injection amount.

Next, control for absorbing the flow characteristic difference between the branch flow paths will be described with reference to FIGS. 6 and 7.
In S211, the flow rate characteristic for each branch flow path 23 stored in the ECU 6 is read.
In S212, it is determined whether or not the flow rate value for each branch flow path 23 with respect to a predetermined fuel pressure is within an allowable range.
In this embodiment, for example, as shown in FIG. 7, it is determined whether or not the flow rate value for each branch flow path 23 with respect to a predetermined fuel pressure P1 is within an allowable range. Here, when the flow rate value of a certain branch flow path 23 is within the allowable range, the process proceeds to S214, and the target injection amount of the injector 4 related to this branch flow path 23 is not corrected.
However, if the flow rate value of a certain branch flow path 23 is outside the allowable range, it is determined that the target injection amount of the injector 4 related to this branch flow path 23 needs to be corrected, and the process proceeds to S213.

In S213, for example, a predetermined value within an allowable range is set as shown in FIG. 7, and the target injection amount of the injector 4 is increased or decreased in accordance with the ratio to the predetermined value to obtain a new target injection amount.
Specifically, if a predetermined value of a certain branch flow path 23 is 1.1 times the flow rate value, the target injection amount is set to 1.1 times to be a new target injection amount.
Therefore, in FIG. 7, the target injection amount is set large in the cylinder No 1 and the target injection amount is set small in the cylinder No 2.

The target injection amount can be adjusted by extending or shortening the injection time.
For example, the allowable range can be provided by setting the upper limit value and the lower limit value with the fuel characteristics of the center product or master product of the manufacturing standard as the center value.

[Effects of Examples]
The common rail 3 of the embodiment is provided with a storage medium 30 in which a flow rate characteristic that is a correlation between the fuel pressure in the pressure accumulating chamber 21 and the fuel flow rate passing through the branch flow channel 23 is stored for each branch flow channel 23.
In the fuel injection device 1 of the embodiment, the ECU 6 reads the storage medium 30 in advance, stores the flow rate characteristics for each branch flow path 23, and drives and controls the injector 4 based on the flow characteristics for each branch flow path 23. ing.

Thereby, the common rail 3 and the storage medium 30 can be correctly associated.
As a result, by reading the storage medium 30, it is possible to accurately and simply store the flow characteristics for each branch flow path 23 in each common rail 3 in each ECU 6 and the like, and to reduce the burden on the operator.
For this reason, the individual common rails 3 and the individual ECUs 6 can be easily and correctly combined when the internal combustion engine 2 is assembled.

[Modification]
Various modifications can be considered for the present invention without departing from the gist thereof.
For example, according to the embodiment, the storage medium 30 stores only the flow rate characteristic for each branch flow path 23 at a predetermined fuel pressure P1 within the working pressure range, but as shown in FIG. The flow rate characteristics for each branch flow path 23 at a plurality of predetermined fuel pressures (two points P1 and P2 in the drawing) may be stored in the storage medium 30. In this case, since flow characteristics at a plurality of fuel pressures can be obtained, for example, continuous data for fuel pressure can be obtained by interpolating between discrete data. It is possible to suppress variations in the flow rate.

  Moreover, according to the Example, although the target injection amount of the injector 4 was changed with the ratio of a predetermined value and a flow value, it does not stick to this aspect. For example, the target injection amount of the injector 4 may be changed based on a difference between a predetermined value and a flow rate value in a certain branch flow path 23.

2 Internal combustion engine 3 Common rail 4 Injector 21 Pressure accumulator
22 Orifice 23 Branching channel 30 Storage medium

Claims (2)

A pressure accumulation chamber (21) for accumulating fuel at high pressure;
A branch passage (23) branched from the pressure accumulating chamber (21) toward each cylinder of the internal combustion engine (2) and provided with an orifice (22);
In the common rail (3) for distributing and supplying high-pressure fuel to the injectors (4) mounted in each cylinder via the branch flow path (23),
A storage medium (30) storing a flow rate characteristic, which is a correlation between the fuel pressure in the pressure accumulating chamber (21) and the fuel flow rate passing through the branch channel (23), is attached to each branch channel (23). Common rail (3) characterized by A common rail (3) according to claim 1;
A control device (6) for driving and controlling the injector (4) according to the operating state of the internal combustion engine (2),
The control device (6) reads the storage medium (30) in advance, stores the flow characteristics for each branch flow path (23), and based on the flow characteristics for each branch flow path (23), A fuel injection device (1) characterized in that the injector (4) is driven and controlled.

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