Patent Grant
8195376
1. Field of the Invention
The present invention relates to a fuel injection control device for a diesel engine, and more specifically relates to a fuel injection control device for a diesel engine for controlling the first fuel injection command soon after a cranking at the time of starting the engine.
2. Related Art
A fuel injection control device for a diesel engine includes a common-rail fuel injection control device. In the common-rail fuel injection control device, fuel is accumulated into a common rail by a high-pressure pump, and the fuel is injected from an injector into a combustion chamber by opening and closing a solenoid valve. The fuel injection timing and fuel injection quantity are controlled by the energization of the solenoid valve in the injector, depending on the specified engine rotating speed, the load or the like. Cranking is started by a starter, and then a cylinder engine in which the fuel is first injected is determined by a cylinder engine determining sensor as well as a fuel injection command signal is issued from an engine control unit (hereinafter, referred to as “ECU”) to the solenoid valve in the injector, whereby the engine is started. Briefly, the fuel injection is started immediately after the cranking has been started and the cylinder engine is determined. In order to increase the rail pressure of the common rail at the time of starting the engine, a discharge rate of the fuel from the high-pressure pump is set up to be maximized shortly after the cranking. With regard to the common-rail fuel injection device mentioned above, the following fuel injection devices are disclosed, wherein the fuel injection is divided into a main injection and a pilot injection before the main injection, so as to slack a combustion by the main injection (for example, see Patent Literature 1), so as to control the pilot injection (for example, see Patent Literature 2) or so as to reduce the amount of white smoke at the time of starting the engine by further injecting a small amount of fuel before the pilot injection or the like (for example, see Patent Literature 3).
Patent Literature 1: the Japanese Patent Laid Open Gazette 3473211
Patent Literature 2: the Japanese Patent Laid Open Gazette 3418996
Patent Literature 3: the Japanese Patent Laid Open Gazette 3580099
In the conventional fuel injection control device described above, the fuel injection is started soon after the cranking, and the time from the immediate aftermath of the cranking until the initiation of the fuel injection is not controlled.
When the fuel is injected before reaching a given injectable common rail pressure, the injection from the injector into the combustion chamber becomes unstable. When the fuel is injected into the combustion chamber on the condition that the combustion chamber is at low temperature just after the cranking, the fuel is not fully evaporated, so a large amount of fuel having no contribution to the combustion is accumulated into the combustion chamber. Since the fuel accumulated into the combustion chamber is discharged from the combustion chamber at once when the ignition is performed thereafter, a great deal of white smoke is generated immediately after starting the engine.
Because the fuel is leaked from the injector, the time until the common rail pressure reaches the given injectable pressure becomes longer, thereby lengthening the time until starting the engine.
In consideration of the aforementioned problems, it's an objective of the present invention to provide a fuel injection control device for a diesel engine that can control the first fuel injection timing and that can reduce the amount of white smoke generated in large amounts soon after starting the engine.
In order to achieve the above-mentioned objectives, in the first embodiment of the present invention, a fuel injection control device for a diesel engine comprises a high-pressure pump, a common rail for accumulating a highly-pressured fuel pressurized and sent from the high-pressure pump, injectors for injecting the fuel supplied from the common rail into a combustion chamber, and a control means for controlling the injectors to perform the first fuel injection command soon after a cranking and after the rail pressure of the common rail reaches a predetermined pressure.
Due to the above construction, the fuel having no contribution to the combustion generated due to a lack of the rail pressure is not leaked and accumulated in the combustion chamber. The amount of fuel leaked from the injector is reduced and the time until the rail pressure reaches the injectable pressure is shortened.
With respect to the second embodiment of the present invention, the fuel injection control device for the diesel engine of the first embodiment further comprises a detecting means for detecting an engine temperature, and a setting means for setting up the predetermined pressure based on the detected engine temperature.
Due to the above construction, the setting pressure is varied depending on the engine temperature.
With respect to the third embodiment of the present invention, the engine temperature of the second embodiment is calculated based on at least the coolant water temperature.
Due to the above construction, the setting pressure is varied depending on the coolant water temperature of the engine.
With respect to the fourth embodiment of the present invention, the fuel injection control device for the diesel engine further comprises a starter for starting an operation by turning on an engine starting switch, a setting means for setting up a non-fuel injection time when the cranking is continuously performed by the starter using battery power, and a control means for controlling the injectors performing the first fuel injection command after the lapse of the non-fuel injection time.
Due to the above construction, the temperature in the combustion chamber is increased due to the cranking during the non-fuel injection time, and the rail pressure of the common rail is increased during the non-fuel injection time.
With respect to the fifth embodiment of the present invention, the fuel injection control device for the diesel engine of the fourth embodiment further comprises a detecting means for detecting the engine temperature, wherein the non-fuel injection time is set based on the detected engine temperature.
Due to the above construction, the non-fuel injection time is varied depending on the engine temperature.
With respect to the sixth embodiment of the present invention, the engine temperature of the fifth embodiment is calculated based on at least the coolant water temperature.
Due to the above construction, the non-fuel injection time is varied depending on the coolant water temperature.
With respect to the seventh embodiment of the present invention, when the non-fuel injection time of the fourth embodiment is longer than the available continuous cranking time, the cranking is performed without injecting the fuel during the available continuous cranking time and the setting means newly sets the non-fuel injection time after the cranking is stopped.
Due to the above construction, battery power is stable without being rapidly decreased, and the continuous operating time of the starter does not become longer than the predefined time.
With respect to the eighth embodiment of the present invention, re-cranking performed during the newly set non-fuel injection time of the seventh embodiment is automatically started.
Due to the above construction, re-cranking is repeated until the engine is started.
With respect to the ninth embodiment of the present invention, the fuel injection command of the fourth embodiment is issued to the injector attached to the cylinder engine having the highest intake air temperature.
Due to the above construction, the first explosion is easily performed, and the compression end temperature of the cylinder engine in which the fuel is secondly injected is increased due to the torque by the cylinder engine in which the first explosion was made, thereby enhancing the ignition.
With respect to the tenth embodiment of the present invention, the pressure feeding quantity of the fuel pressurized and sent from the high-pressure pump per unit time of the fourth embodiment is reduced, so that the time until the fuel injection command is issued approximately coincides with the time until the rail pressure of the common rail reaches a target pressure.
Due to the above construction, the fuel pressure feeding quantity from the high-pressure pump to the common rail just after starting the cranking needs not to be maximized.
With respect to the eleventh embodiment of the present invention, the setting means and the control means of the fourth embodiment are set up so as not to be performed when the voltage of the battery is a predetermined value or lower.
Due to the above construction, excessive burdens are not placed on the battery.
As described above, according to the first embodiment of the present invention, because the fuel having no contribution to the combustion generated due to a lack of the rail pressure is not accumulated in the combustion chamber, the amount of white smoke generated in large amounts soon after starting the engine can be reduced. The amount of fuel leaked from the injector is reduced and the time until the rail pressure reaches the injectable pressure is shortened, so that the time until the engine is started can be shortened.
According to the second embodiment of the present invention, in addition to the effect of the first embodiment, since the setting pressure is varied depending on the engine temperature, the white smoke is reduced and the optimal engine starting time is set so that efficient engine starting can be performed.
According to the third embodiment of the present invention, in addition to the effect of the second embodiment, since the setting pressure is varied depending on the coolant water temperature, the engine temperature most suitable for starting the engine can be calculated and more efficient engine starting can be performed.
According to the fourth embodiment of the present invention, as the temperature in the combustion chamber is increased due to the cranking during the non-fuel injection time and the rail pressure of the common rail is increased during the non-fuel injection time, the fuel having no contribution to the combustion accumulated in the combustion chamber in the first fuel injection can be decreased, whereby the amount of white smoke generated in large amounts soon after starting the engine can be reduced.
According to the fifth embodiment of the present invention, in addition to the effect of the fourth embodiment, since the non-fuel injection time is varied depending on the engine temperature, the white smoke is reduced and the optimal engine starting time is set so that efficient engine starting can be performed.
According to the sixth embodiment of the present invention, in addition to the effect of the fifth embodiment, since the non-fuel injection time is varied depending on the coolant water temperature, the engine temperature most suitable for starting the engine can be calculated and more efficient engine starting can be performed.
According to the seventh embodiment of the present invention, the battery power is stable without being rapidly decreased, and the continuous operating time of the starter does not become longer than the predefined time, so the burden on the battery or the starter can be reduced.
According to the eighth embodiment of the present invention, in addition to the effect of the seventh embodiment, since re-cranking is repeated until the engine is started, an operator need not turn on the engine starting switch again and again, thereby improving the usability.
According to the ninth embodiment of the present invention, in addition to the effect of the fourth embodiment, since the first explosion is easily performed, and the compression end temperature of the cylinder engine in which the fuel is secondly injected is increased due to the torque by the cylinder engine in which the first explosion was made, and the ignition is enhanced, the fuel having no contribution to the combustion accumulated in the combustion chamber can be decreased, whereby the amount of white smoke generated in large amounts soon after starting the engine can be further reduced.
According to the tenth embodiment of the present invention, in addition to the effect of the fourth embodiment, since the fuel pressure feeding quantity from the high-pressure pump to the common rail just after starting the cranking needs not to be maximized, the driving force of the high-pressure pump needed soon after starting the cranking can be reduced. The burden on the starter can be lowered, whereby the cranking rotation speed is increased.
According to the eleventh embodiment of the present invention, in addition to the effect of the fourth embodiment, the excessive burden on the battery is decreased so that the impossibility of starting the engine can be avoided.
Next, embodiments of the present invention will be described with reference to the drawings.
Referring to
The common rail 24 includes a rail pressure sensor 30 and a pressure regulating valve 31. The ECU 32 detects the fuel pressure in the common rail 24 by the rail pressure sensor 30, and the fuel pressure is always regulated to an optimal pressure by opening or closing the pressure regulating valve 31. In other words, a stable injection pressure can be secured when an engine rotates at low speed and so on, regardless of an engine rotation speed or a load.
The respective injectors 26, which are provided with each of the cylinder engines, each include a solenoid valve 28 that opens or closes by an ON/OFF signal from the ECU32 and a needle valve 29 for injecting the fuel into the fuel chamber 49 at high pressure. When the solenoid valve 28 is energized and is opened, part of the high-pressure fuel flows out to a surplus fuel pipe 27, and the pressure behind the needle valve 29 is lowered so as to move up the needle valve 29 and open its that the fuel injection is performed. When the energization of the solenoid valve 28 is stopped, the high-pressure fuel is supplied behind the needle valve 29 again so as to move down the needle valve 29 and close its that the fuel injection is terminated. In the common rail fuel injection control device 20, the ECU 32 issues a signal to each of the solenoid valves 28 of the injectors 26, whereby the fuel injection timing and the injection quantity are controlled.
The ECU32 controls the fuel injections by the injectors 26 based on signals from the various sensors, internal programs and data. The ECU32 controls the high-pressure pump 22 and calculates a target pressure for the common rail 24 based on the engine condition. It also adjusts the amount of high-pressure fuel supplied to the common rail 24 so that the output from the rail pressure sensor 30 becomes the target value. The ECU32 is electrically connected to various sensors, such as a cylinder engine determining sensor 34 provided with a camshaft, an engine rotation speed sensor 35 provided with a crankshaft 51 or a flywheel, an acceleration opening degree sensor 36, an intake pressure sensor 37, an intake temperature sensor 38 provided with an intake port 46, a fuel temperature sensor 39, a coolant water temperature sensor 40 provided with a water jacket 52 formed outside of the combustion chamber 49 and a lubricant oil temperature sensor 41, including an engine starting switch 33 that transmits a starter signal to the ECU 32 and the starter 44. The ECU32 also includes a non-fuel injection time setting means 42 for setting up the after-mentioned non-fuel injection time tq and a battery voltage detecting means 43 for detecting a battery voltage (not shown). The ECU32 controls the engine by the signals transmitted from the aforementioned various sensors or the like.
Next, the first embodiment of a fuel injection control at the time of starting the engine will be described.
Referring to
In this regard, the cylinder engine in which the intake air temperature is increased the most as mentioned above means the cylinder engine closest to a means for warming the intake air of the engine starting at a low temperature. For example, when multiple cylinder engines are arranged in series as in the present embodiment, an air heater as the means for warming the intake air is disposed at an inlet for the intake air of an intake manifold. Because the intake air warmed by the air heater is supplied to the respective cylinder engines, the cylinder engine closest to the mounting location of the air heater becomes the cylinder engine in which the intake air temperature is increased the most.
Meanwhile, when it is not the case that tq<tb at Step S 104 (No, at S 104), the cranking is continuously performed for the above-mentioned tb time (S111), and the cranking is stopped once (S 112). Since the cranking is stopped, the battery voltage is recovered. Next, in the case when n=n+1, i.e., n=1 (S 113), the operator turns on the engine starting switch again (S 115, No, at S 114). In this regard, when an automatic restart is set up, the operator need not turn on the engine starting switch again, and Step S 115 is omitted (Yes, at S 114). The ECU 32 newly sets the non-fuel injection time (tq−(tb×n)), i.e., (tq−(tb×1) (S 116). Retuning to Step S 104 again, when tq<tb with respect to the non-fuel injection time tq newly set up at Step S 116 (Yes, at S 104) after the fuel injection data is determined (S 105), re-cranking is performed (S 106). When the non-fuel injection time tq newly set at Step S 116 goes by (S 107), as with the case of n=0, the determination of the cylinder engine (S 108) and the first fuel injection command to the injector 26 (S 109) are performed, so that the engine is started due to the fuel injection (S 110). Until the non-fuel injection time tq newly set satisfies the condition tq<tb (Yes, at S 104), the continuous cranking for the tb time is repeated (S 111 to S 116, No, at S 104).
Incidentally, when the main power supply of the ECU 32 is turned on, the ECU 32 detects the battery voltage for use in the fuel injection control device for the diesel engine 20 by the battery voltage detecting means 43. When the detected battery voltage is a predetermined value or lower, the ECU 32 ensures that the fuel injection control is not performed before the engine starting switch is turned on at Step S 101. Due to the above setting, the excessive burden is not placed on the battery, whereby the incapability of the engine starting can be avoided.
Next, an explanation will be given on the relationship between the cranking, the energization of the solenoid valve and the non-fuel injection time tq in the fuel injection control at the time of starting the engine as described above.
Referring to
Referring to
Referring to
An explanation will be given on the relationship between the white smoke concentration and the coolant water temperature Tw, the relationship between the white smoke concentration and the non-fuel injection time tq as well as the relationship between the non-fuel injection time tq and the coolant water temperature Tw.
Referring to
Referring to
Referring to
As seen from above, in the fuel injection control device 20 in which the first fuel injection command is performed after the lapse of the non-fuel injection time tq as shown in the flow diagram of
Since re-cranking is repeated until the engine starting when the engine automatic restarting is set up (Yes, S 114 in
Next, an explanation will be given on the target pressure arrival time of the rail pressure in the common rail 24 using the non-fuel injection time tq.
Referring to
In this regard, in the aforementioned embodiment, the non-fuel injection time is set up corresponding to the coolant water temperature, but it may be set up to be constant within the limit of the available continuous cranking time.
In the aforementioned embodiment, also, the coolant water temperature is used as the engine temperature, but the intake temperature, lubricant oil temperature or the fuel temperature or the like may be available. They can be used to evaluate the engine temperature, and a combination thereof including the coolant water temperature may be also used.
Further, in the aforementioned embodiment, although six injectors are used, one or more injectors may be used.
Next, the second embodiment of the fuel injection control at the time of starting the engine will be described.
Referring to
Here, an explanation will be given on a relationship between the common rail pressure, the energization of the solenoid valve and the opening/closing of the needle valve at the time of starting the engine.
Referring to
Meanwhile, referring to
Returning to
An explanation will be given on the relationship between the set rail pressure P1 and the coolant water temperature Tw as well as the white smoke concentration and the coolant water temperature Tw.
Referring to
Referring to
As seen from above, in the fuel injection control device 20, which the first fuel injection command just after the cranking is issued to the injector 26 after the common rail pressure Pr reaches the setting rail pressure P1 as shown in the flow diagram of
In this regard, in the aforementioned embodiment, the set rail pressure is set up depending on the coolant water temperature, but it may be set to be constant.
In the aforementioned embodiment, also, the coolant water temperature is used as the engine temperature, but the intake temperature, lubricant oil temperature or the fuel temperature or the like may be available. They can be used to evaluate the engine temperature, and a combination thereof including the coolant water temperature may be used also.
Further, in the aforementioned embodiment, although six injectors are used, one or more injectors may be used.
The present invention is applicable to the fuel injection control device for the diesel engine, especially in the fuel injection control device for the diesel engine controlling the first fuel injection command soon after the cranking at the time of starting the engine.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-54596 | Mar 2007 | JP | national |
| 2007-54597 | Mar 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/053806 | 3/4/2008 | WO | 00 | 9/3/2009 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2008/111422 | 9/18/2008 | WO | A |
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| Number | Date | Country |
|---|---|---|
| 11-270385 | Oct 1999 | JP |
| 2003-083103 | Mar 2003 | JP |
| 2003-106195 | Apr 2003 | JP |
| 3418996 | Jun 2003 | JP |
| 3473211 | Dec 2003 | JP |
| 3580099 | Oct 2004 | JP |
| 2006-188971 | Jul 2006 | JP |
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| Number | Date | Country | |
|---|---|---|---|
| 20100100303 A1 | Apr 2010 | US |
