JP2003028029A - Accumulator fuel injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accumulator fuel injector capable of accurately compensating a current carrying amount of a solenoid valve according to a change of ambient temperature. SOLUTION: In this injector, a target current value of the discharge amount- controlling solenoid valve 8 is calculated on the basis of target common rail pressure, while a coil temperature of the solenoid valve 8 detected by a temperature sensor 19 (step S302) is converted into a resistance value of the solenoid coil in that temperature on the basis of previously-obtained actually-measured data (step S304), and the target current value is corrected on the previously- obtained actually-measured data with the resistance value of the solenoid coil as an index and is found as a correction target current value (step S306). Thereby, even if a change of the resistance value of the solenoid coil comes out, a required current flows through the solenoid coil unlike before.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called pressure accumulation type fuel injection device, and more particularly to a device for stabilizing pressure control characteristics and improving reliability.

[0002]

2. Description of the Related Art Conventionally, as this type of device, for example,
As disclosed in JP-A-11-294244 and the like, fuel pumped up from a fuel tank by a feed pump is supplied to a high pressure pump via a solenoid valve, and the fuel is brought into a predetermined high pressure state by the high pressure pump. After that, the fuel is supplied to a common rail to which a plurality of injection nozzles are connected, the injection nozzles are opened by electronic control, and high-pressure fuel is supplied to the fuel chamber of each cylinder of the diesel engine. Has become. In such a pressure-accumulation fuel injection device, a solenoid valve provided between the feed pump and the high-pressure pump generally uses a current-driven proportional solenoid to adjust the amount of fuel pumped from the fuel tank by the feed pump to the high-pressure pump. A valve is used, and the amount of fuel supplied to the high-pressure pump can be adjusted by controlling the amount of electricity supplied. by the way,
The electrical characteristics of this solenoid valve are as follows:
In particular, it is ideal that it is constant regardless of the ambient temperature, but actually, the resistance value of the electromagnetic coil changes depending on the temperature. Therefore, even before and after the change in coil resistance, the actual current value may be different before and after the change in coil resistance, even if the value of the current supplied to the energizing circuit that energizes the solenoid valve from the control unit is the same. As a result, the control characteristic of the pressure in the common rail (common rail pressure controllability) deteriorates, and finally there is the inconvenience that the discharge amount from the injection nozzle fluctuates. Therefore, conventionally, as a measure for compensating the energization amount according to the resistance value change of the solenoid valve coil due to such a change in ambient temperature, for example, the actual energization current is detected and A so-called feedback control method of the difference, a method of detecting the fuel temperature or the temperature of the engine cooling water, and correcting the energizing current of the solenoid valve according to the temperature have been proposed.

[0003]

However, in the former method, fast response cannot be expected from the viewpoint of ensuring control stability, and it is difficult to say from a practical point of view. Further, in the latter method, since the fuel temperature and the cooling water temperature are used as the temperature of the solenoid valve, there is a problem that the accuracy is insufficient. The present invention is
The present invention has been made in view of the above circumstances, and provides a pressure-accumulation fuel injection device that can accurately compensate the energization amount of a solenoid valve according to a change in ambient temperature and has good common rail pressure controllability. Another object of the present invention is to provide a pressure-accumulation fuel injection device capable of ensuring a reliable engine start.

[0004]

In order to achieve the above object, the pressure-accumulation fuel injection device according to the present invention is such that fuel in a fuel tank is supplied to a high-pressure pump via a discharge control solenoid valve, High-pressure fuel is pumped to a common rail by a high-pressure pump, and the high-pressure fuel stored in the common rail is configured to be injectable from the fuel injection valve by controlling the operation of a fuel injection valve connected to the common rail. An apparatus comprising: a temperature detecting means for detecting a temperature of the discharge amount controlling solenoid valve; and an operation controlling means for controlling an operation of the discharge amount controlling solenoid valve, wherein the operation controlling means is a predetermined device. The target current value of the discharge amount control solenoid valve calculated based on the calculation method of is actually flown to the discharge amount control solenoid valve based on the value detected by the temperature detection means. Flow in which is configured to perform the energization to said discharge amount control electromagnetic valve is corrected so as to be the target current value.

In such a configuration, the target current value is corrected based on the change in the resistance value of the electromagnetic coil due to the change in ambient temperature so that the current actually flowing in the electromagnetic coil matches the target current. The common rail pressure controllability is improved by energizing and ensuring accurate energization of the electromagnetic coil.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. The members, arrangements, and the like described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention. First, the configuration of a pressure-accumulation fuel injection device (hereinafter referred to as the “present device”) in the embodiment of the present invention will be described with reference to FIG. The present device is provided corresponding to each cylinder of a diesel engine (not shown), a fuel injection valve (injector) 1 for injecting and supplying fuel to the cylinder, and a common rail 2 for storing high-pressure fuel to be supplied to the fuel injection valve 1. And a high-pressure pump unit 3 for pumping high-pressure fuel to the common rail 2, a fuel tank 4, and an electronic control unit (described as “ECU” in FIG. 1) 5 for performing operation control and the like described later. It has been done.
The high-pressure pump unit 3 includes a supply pump 6, a feed pump 7 including a so-called gear pump coaxially attached to a camshaft 6a of the supply pump 6,
The discharge amount control solenoid valve 8 for controlling the fuel supply amount to the supply pump 6 is configured as a main component.

The supply pump 6 is a well-known and well-known so-called plunger type, and its schematic configuration will be described here. The supply pump 6 in the embodiment of the present invention includes the first and second cylinders 9a and 9b.
And has first and second plungers 10a, 10b,
The corresponding first and second plunger chambers 11a,
11b has been formed. The first and second plungers 10a and 10b have first and second cams (not shown) attached to a camshaft 6a whose end portions not shown are connected to a crankshaft (not shown) of the engine. , And the first and second cylinders 9 according to the movement of the cam accompanying the rotation of the camshaft 6a.
The fuel pressure in the first and second plunger chambers 11a and 11b is increased by the reciprocating movement in the a and 9b.

The feed pump 7 comprises a so-called gear pump, is attached to the camshaft 6a, and the rotation of the feed pump 7 sucks up the fuel in the fuel tank 4 and supplies the fuel via the discharge control solenoid valve 8. First and second plunger chambers 11a and 11b ahead of the pump 6
It is provided to supply to. In the embodiment of the present invention, the suction side of the feed pump 7 is
It is connected to the fuel tank 4 via the first connection passage 13a, and the discharge side of the feed pump 7 is connected to the second connection passage 13a.
It is connected to the fuel filter 12 via b. Then, the fuel filter 12 and the inlet side of the discharge amount control solenoid valve 8 are connected via the third connection passage 13c, and the discharge amount control solenoid valve 8 can be cleaned of dust and the like by the fuel filter 12. The applied fuel is designed to flow in. The discharge amount control solenoid valve 8 is formed by using a current-driven proportional solenoid valve, and the open state can be controlled by controlling the energization amount.
The energization amount and the open state are in a substantially proportional relationship. In the embodiment of the present invention, the flow amount of fuel increases as the amount of electricity supplied increases. The amount of high-pressure fuel that is pressure-fed to the common rail 2 is determined by the amount of fuel supplied to the first and second plunger chambers 11a and 11b via the discharge amount control solenoid valve 8. Therefore, the discharge amount controlling solenoid valve 8 functions as a solenoid valve for controlling the pressure of the common rail 2.

On the outlet side of the discharge amount controlling solenoid valve 4, fourth and fifth valves are provided so as to join near the outlet side.
The connection passages 13d and 13e are connected. That is, the fourth and fifth connection passages 13d and 13e are provided so as to connect the outlet side of the discharge amount control solenoid valve 8 and the common rail 2, and, as will be described below, the first and second connection passages, respectively. It is connected to the plunger chambers 11a and 11b. That is, in the fourth connection passage 13d, between the outlet side of the discharge amount control solenoid valve 8 and the common rail 2, from the outlet side of the discharge amount control solenoid valve 8 to the first side.
Intake valve 14a and the first discharge valve 15a are sequentially provided, and the first plunger chamber 11a is provided at a portion of the fourth connection passage 13d between the first intake valve 14a and the first discharge valve 15a. First plunger chamber connection passage 16a communicating with
Has been connected. In addition, in the fifth connection passage 13e, between the outlet side of the discharge amount controlling solenoid valve 8 and the common rail 2, from the outlet side of the discharge amount controlling solenoid valve 8 to the second intake valve 14b and the second side. The discharge valve 15a is sequentially provided, and the second suction valve 14b and the second discharge valve 1 are provided.
A second plunger chamber connection passage 16b communicating with the second plunger chamber 11b is connected to a portion of the fifth connection passage 13e between the portions 5a.

Then, the first and second suction valves 14a, 1
4b has a check valve structure so that fuel does not flow from the first and second plunger chambers 11a, 11b side to the discharge amount control solenoid valve 8 side, and the first and second plungers 10a and 10a are provided. , 10b are located in the suction stroke state and the discharge amount control solenoid valve 8 is opened, the fuel sucked up from the fuel tank 4 by the feed pump 7 becomes
Through the suction valves 14a, 14b of the
It is designed to flow into the plunger chambers 11a and 11b. The first and second discharge valves 15a and 15b are
The check valve structure prevents the fuel from flowing from the common rail 2 side to the side to which the first and second intake valves 14a and 14b are connected, and the first and second plungers 10a and 10b are Located in the compression stroke state, the first and second
When the fuel in each of the plunger chambers 11a, 11b reaches a predetermined high pressure state, the first and second plunger chambers 11a, 11b
The high-pressure fuel flows into the common rail 2 through the first and second discharge valves 15a and 15b. In order to return the surplus fuel in the common rail 2 to the fuel tank 4, a sixth connection passage 13f and a relief valve 17 are provided between the two so that the fuel pressure in the common rail 2 is kept at a predetermined pressure. In the above case, the fuel is returned to the fuel tank 4 via the relief valve 17.

The common rail 2 is provided with a pressure sensor 18 for detecting the internal pressure, and the detection signal thereof is input to the electronic control section 5. Further, in the embodiment of the present invention, a temperature sensor 19 for detecting the temperature of the electromagnetic coil (not shown) of the discharge amount controlling solenoid valve 8 is provided at an appropriate portion of the discharge amount controlling solenoid valve 8. The detection signal is also input to the electronic control unit 5. The electronic control unit 5 is realized by being configured mainly by, for example, a microcomputer, and in addition to the detection signals from the pressure sensor 18 and the temperature sensor 19, the engine speed, the accelerator opening signal, and the like. Various signals necessary for engine control are input (not shown), and based on these input signals, drive control of the discharge amount control solenoid valve 8 is performed so that the fuel pressure in the common rail 2 becomes the target fuel pressure. In addition to the above, the operation control of the fuel injection valve 1 and the like are performed. The discharge amount control solenoid valve 8 is energized by an energization drive circuit (denoted as “DRV” in FIG. 1) 20 in response to an output signal (control signal) from the electronic control unit 5. ing. The energization drive circuit 20 has a known and well-known circuit configuration configured by using a transistor or the like so as to flow a current to the electromagnetic coil of the discharge amount control solenoid valve 8 in response to a signal from the electronic control unit 5. It will be.

Next, drive control of the discharge amount controlling solenoid valve 8 performed by the electronic control unit 5 will be described with reference to FIGS. 2 to 4. First, the overall processing procedure of drive control of the discharge amount control solenoid valve 8 will be described with reference to FIG. First, the process shown in FIG. 2 is executed as one sub-routine process in a main routine process (not shown). To be more specific, when the processing is started, first, the target common rail pressure is calculated (see step S100 in FIG. 2). The target common rail pressure is calculated based on the target injection fuel calculated based on signals such as the engine speed and the accelerator opening signal, the actual common rail pressure detected by the pressure sensor 18, and the like in a main routine process (not shown). It has been calculated. Then, based on the calculated target common rail pressure, the target current value to be passed to the discharge amount control solenoid valve 8 is calculated by a preset arithmetic expression (see step S200 in FIG. 2). Next, based on the temperature of the electromagnetic coil (not shown) of the discharge control electromagnetic valve 8 detected by the temperature sensor 19, correction (details described later) is performed for the target current value calculated in the process of step S200. (See step S300 in FIG. 2). Then, the discharge amount control solenoid valve 8 is energized with the correction target current value corrected in the process of step S300 (see step 400 of FIG. 2), and the process returns to the main routine process (not shown). ing.

FIG. 3 shows a subroutine flowchart showing a specific processing procedure of the current correction processing in step S300 described above, and the content thereof will be described below with reference to the drawing. When the process starts
First, the coil temperature is input (Fig. 3).
See step S302). That is, the temperature sensor 19
The temperature (coil temperature) of the electromagnetic coil (not shown) of the discharge amount controlling solenoid valve 8 detected by is read by the electronic control unit 5. Next, the detected coil temperature is converted into the resistance value (electrical resistance value) of the electromagnetic coil at that temperature (step S304 in FIG. 3).
reference). That is, in the embodiment of the present invention, for example, the relative relationship between the coil temperature and the resistance value of the electromagnetic coil as shown in FIG.
It is stored in a predetermined storage area of the electronic control unit 5. The relative relationship between the coil temperature and the resistance value of the electromagnetic coil may be stored in a table format.
The relative relationship between the two may be stored as an arithmetic expression, and there is no need to be limited to a particular format, and various selections are possible. Then, based on the relative relationship between the coil temperature and the resistance value of the electromagnetic coil stored in advance in this manner, step S30
The resistance value of the electromagnetic coil with respect to the coil temperature input in 2 is obtained.

Next, based on the resistance value of the electromagnetic coil obtained as described above, the correction current obtained by correcting the target current calculated in the process of step 200 is calculated ( (See step S306 in FIG. 3). That is, the target current calculated in the process of step S200 is when the resistance value of the electromagnetic coil is at a predetermined value that is set in advance (in other words, when the coil temperature is at a predetermined temperature). However, since the resistance value of the electromagnetic coil changes depending on the ambient temperature, step S
The actual resistance value of the electromagnetic coil when the target current is calculated in 200 is not necessarily the predetermined value used as the reference for calculating the target current. Specifically, generally, the resistance value of the electromagnetic coil tends to increase as the coil temperature increases. Therefore, even if a signal is output from the electronic control unit 5 to the energization drive circuit 20 corresponding to the target current calculated in the process of step S200 and the energization is performed according to the output signal, the actual electromagnetic coil The resistance value of
Unlike the predetermined value used to calculate the target current in step S200, for example, if the coil temperature is higher than the predetermined temperature, the actual step S200 is
The current value becomes lower than the target current calculated in the process of 200.

Therefore, in the embodiment of the present invention,
In step 306, the target current value calculated in the process of step S200 is corrected based on the actual measurement data,
It is calculated as a corrected target current value, and energization is performed at this corrected target current value. That is, specifically,
At various target currents, when the resistance value of the electromagnetic coil of the discharge amount controlling solenoid valve 8 changes, in order to actually set the current of the electromagnetic coil as the target current, the energization drive circuit 20
To which the current value to be commanded, that is, the corrected target current value (= target current value calculated in step S200 + correction value) should be measured in advance, and based on the measured data, the resistance value of the electromagnetic coil And the target current value calculated in step S200 and stored in a predetermined storage area of the electronic control unit 5 as a conversion table or an arithmetic expression for obtaining the corrected target current value. Then, in step S306, the resistance value of the electromagnetic coil obtained in step S304 and the corrected target current value for the target current value calculated in step S200 are stored in advance in the electronic control unit 5 as described above. For example, it is obtained from the conversion table, and the process returns to the subroutine processing shown in FIG.

As a result, even if the resistance value of the electromagnetic coil of the discharge control electromagnetic valve 8 changes, the target current calculated in step S200 can be reliably ensured as the current supplied to the electromagnetic coil. . The output from the electronic control unit 5 to the energization drive circuit 20 outputs the corrected target current value obtained by the electronic control unit 5 as described above, and is converted into a signal format required in the energization drive circuit 20. Whether it is converted, or whether the electronic control unit 5 converts the corrected target current value into a control signal necessary for energization of the energization drive circuit 20 is a matter within the range of selection, and either one may be used. Is. Further, in the above configuration example, the temperature sensor 19
According to the temperature detecting means, the electronic control unit 5 performs steps S100, S200, S300 and S400 shown in FIG.
The operation control means is realized by executing the above.

Further, the temperature sensor 19 may be attached directly to an electromagnetic coil (not shown) of the discharge amount controlling solenoid valve 8, but it may be attached to the surface of the discharge amount controlling solenoid valve 8. Then, the detected value may be used as the coil temperature. Further, the type of the temperature sensor 19 is not particularly limited to a particular type and may be arbitrarily selected.

[0018]

As described above, according to the present invention, even if the resistance value of the electromagnetic coil of the solenoid valve for controlling the discharge amount changes depending on the ambient temperature, the energizing amount is set so that the target current actually flows. Since it is configured to correct the current, it is possible to accurately energize the electromagnetic coil, which ensures stable rail pressure control, reduces the variation in control due to temperature, and is more reliable than before. The effect is that a high pressure accumulation type fuel injection device is provided. Also,
Since stable rail pressure control is ensured, accurate fuel injection can be realized, and as a result, reliable engine starting can be ensured.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of a pressure accumulation type fuel injection device according to an embodiment of the present invention.

2 is a subroutine flow chart showing an overall processing procedure of drive control of a discharge amount controlling solenoid valve executed by an electronic control unit used in the pressure accumulation type fuel injection device shown in FIG. 1. FIG.

FIG. 3 is a subroutine flowchart showing a specific processing procedure of current correction processing in the subroutine flowchart shown in FIG.

4 is a characteristic diagram showing a relative relationship between a coil temperature used for resistance conversion processing and a resistance value of an electromagnetic coil in the subroutine flow chart shown in FIG.

[Explanation of symbols]

1 ... Fuel injection valve 2 ... Common rail 5 ... Electronic control unit 6 ... Supply pump 8 ... Discharge amount control solenoid valve 18 ... Pressure sensor 19 ... Temperature sensor 20 ... energization drive circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 51/00 F02M 51/00 FF term (reference) 3G066 AA07 AB02 AC09 BA12 BA66 CA04U CD26 CE22 CE29 DA06 DC04 DC08 DC13 DC18 3G301 HA02 JA11 LB17 LC01 NC02 ND01 PB00A PB03Z PB08A PE01Z PF03Z PG02A

Claims (3)

[Claims] 1. The fuel in a fuel tank is supplied to a high-pressure pump via a discharge control solenoid valve, the high-pressure pump pumps high-pressure fuel to a common rail, and the high-pressure fuel stored in the common rail is supplied to the common rail. A pressure-accumulation fuel injection device configured to be able to inject from the fuel injection valve by controlling the operation of the connected fuel injection valve, wherein the temperature detection means detects the temperature of the discharge amount control solenoid valve, and the discharge An operation control means for controlling the operation of the solenoid valve for controlling the amount, the operation control means, the target current value of the solenoid valve for controlling the discharge amount calculated based on a predetermined calculation method, the temperature Based on the value detected by the detection means, the current actually flowing to the discharge amount controlling solenoid valve is corrected to the target current value, and the discharge amount controlling solenoid valve is energized. Characteristic accumulator fuel injection device. 2. The fuel in a fuel tank is supplied to a high-pressure pump via a discharge amount control solenoid valve, the high-pressure fuel is pressure-fed to a common rail by the high-pressure pump, and the high-pressure fuel stored in the common rail is fed to the common rail. A pressure accumulation type fuel injection device configured to be capable of injecting from the fuel injection valve by controlling the operation of the connected fuel injection valve, wherein a temperature sensor that detects the temperature of the discharge amount control solenoid valve, and the discharge amount An electronic control unit that controls the operation of the control solenoid valve, and an energization drive circuit that energizes the discharge amount control solenoid valve according to the output signal of the electronic control unit, the electronic control unit, The target current value of the discharge amount control solenoid valve calculated based on a predetermined calculation method is set to the electric current that actually flows to the discharge amount control solenoid valve based on the output signal of the temperature sensor. Is calculated as a corrected target current value by correcting the target current value to the target drive current value, and the corrected target current value is output to the energization drive circuit. A pressure-accumulation fuel injection device characterized by energizing a control solenoid valve. 3. The electronic control unit uses the relative relationship between the temperature of the discharge amount controlling solenoid valve and the resistance value of the electromagnetic coil, which is created based on actual measurement data and stored in the electronic control unit, The temperature detected by the temperature sensor is converted into a resistance value of the electromagnetic coil, and in the resistance value of the electromagnetic coil obtained by the conversion, the actual current of the electromagnetic coil is
In order to obtain the target current value of the solenoid valve calculated based on a predetermined calculation method, the corrected target current value to be output to the energization drive circuit, the resistance value of the solenoid valve based on the actual measurement data and the target current value 3. The pressure-accumulation fuel injection device according to claim 2, wherein it is determined based on a mutual relationship between the correction target current value and the corrected target current value.