JP2016061280A - Fuel injection system, compression ignition type internal combustion engine and fuel injection system control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection system, a compression ignition type internal combustion engine burning liquefied gas fuel and a fuel injection system control method capable of stably supplying the liquefied gas fuel while preventing vaporization thereof by reducing pressure pulsation in a high pressure pump which supplies the liquefied gas fuel sent from a low pressure pump after increasing pressure thereof.SOLUTION: A fuel injection system 1 has a high pressure pump 10 which discharges liquefied gas fuel F supplied from a low pressure pump 12. When determining that pressure pulsation is generated in a gallery 10a of the high pressure pump 10, the fuel injection system 1 performs control of supply pressure of the low pressure pump 12 in a manner that superimposes a stabilization control signal which has an opposite phase to the pressure pulsation and allows correction pressure for stabilizing the pressure pulsation to be generated on a reference control signal corresponding to average target supply pressure of the low pressure pump 12.SELECTED DRAWING: Figure 2

Description

  In the compression ignition internal combustion engine using liquefied gas fuel as a fuel, the present invention reduces the pressure pulsation in the high pressure pump that supplies the liquefied gas fuel supplied from the low pressure pump at a high pressure, thereby preventing the vaporization of the liquefied gas fuel. The present invention relates to a fuel injection system capable of stably supplying liquefied gas fuel, a compression ignition internal combustion engine, and a control method for the fuel injection system.

  In general, in a compression ignition type internal combustion engine using liquefied gas fuel as fuel, as shown in FIG. 1, fuel injection into each cylinder is performed by using liquefied gas fuel F stored in a fuel tank 11 in a liquid phase state. The pressure is increased to about 3 MPa by a low-pressure pump (feed pump) 12 and supplied to the high-pressure pump 10, and the liquefied gas fuel F is further pressurized to about 60 MPa to 80 MPa by the high-pressure pump 10, and then passed through the common rail 14. To the fuel injection valve 15 in each cylinder.

  As shown in FIGS. 3 and 4, the high-pressure pump 10 has a gallery 10a for storing the liquefied gas fuel F supplied from the low-pressure pump 12, and a high-pressure pump connected to the gallery 10a through a communication passage 10d. The chamber 10c includes an opening / closing valve 10e provided in the communication passage 10d, and a plunger 10b provided in the high-pressure chamber 10c and reciprocating.

  The liquefied gas fuel F stored in the gallery 10a is sucked into the high-pressure chamber 10c by the opening / closing control of the on-off valve 10e and the reciprocating control of the plunger 10b, and the high pressure chamber 10c is pressurized. The liquefied liquefied gas fuel F is discharged (pressure-fed) to the common rail 14. The discharge amount of the liquefied gas fuel F to the common rail 14 is controlled by the closing timing of the on-off valve 10e according to the pressure at the time t in the common rail 14, and the liquefied gas fuel F that does not need to be discharged to the common rail 14 10c is returned to the gallery 10a via the communication passage 10d.

  When this liquefied gas fuel F is gasified, the high pressure pump 10 impedes the supply of the liquefied gas fuel F to the common rail 14, so that the pressure Pg (t) inside the gallery 10a is always liquefied in relation to the temperature T. It is necessary to maintain a value exceeding the saturated vapor pressure Ps (T) of the gas fuel F, and by adjusting the supply pressure (discharge pressure) Po (t) of the low-pressure pump 12, the pressure Pg ( Feedback control is performed so that t) becomes a target pressure exceeding the saturated vapor pressure Ps (T). Since this saturated vapor pressure Ps (T) is determined by the temperature T of the liquefied gas fuel F in the gallery 10a, this temperature T is detected by the temperature sensor 31 provided in the gallery 10a, and the saturated vapor pressure Ps (T) is calculated. The target pressure is set with a margin for the saturated vapor pressure Ps (T).

  On the other hand, in the high pressure pump 10, the liquefied gas fuel F stored in the gallery 10a is sucked into the high pressure chamber 10c from the gallery 10a and returned from the high pressure chamber 10c to the gallery 10a. Since the pressure Pg (t) changes, a pressure pulsation synchronized with the pump rotation speed and plunger discharge speed of the high-pressure pump 10 occurs. This pressure pulsation increases when the return amount is large. In particular, when the discharge amount of the liquefied gas fuel F from the high-pressure pump 10 to the common rail 14 becomes zero (zero discharge), the entire amount of the liquefied gas fuel F is stored in the gallery 10a. This pressure pulsation becomes large. When this pressure pulsation becomes large, the amplitude of the pressure pulsation may be about ± 1 MPa with respect to the average pressure inside the gallery 10a.

  When this pressure pulsation occurs, the feedback control of the low-pressure pump, which is performed according to the average pressure inside the gallery 10a, is affected, resulting in a problem that a control deviation occurs due to the phase of this pressure pulsation. When the pressure pulsation amplitude further increases, the pressure Pg (t) inside the gallery 10a temporarily changes to the saturated vapor pressure Ps (T) of the liquefied gas fuel F as indicated by A (thin line) in FIG. ), Gasification occurs, and liquid separation occurs, causing a problem that the discharge amount of the liquid gas fuel F from the high-pressure pump 10 to the common rail 14 is hindered.

  As a measure against this pressure pulsation, in a fuel injection device in which liquefied gas fuel is supplied to a fuel gallery of a high-pressure pump via a feed pipe, a flow path expansion pipe having a flow area larger than the flow area of the fuel gallery Is disposed between the feed pipe and the fuel gallery so that the flow path expansion pipe functions as an accumulator, and when fuel is supplied to the fuel gallery during the plunger intake stroke, Since the fuel replenishment amount is added to the feed amount by the feed pump, a fuel injection device has been proposed in which the pressure drop in the fuel gallery is reduced and the pressure pulsation in the fuel gallery is reduced (for example, Patent Document 1). reference).

  However, in this fuel injection device, a pressure accumulation chamber is provided between the feed pipe and the fuel gallery to reduce pressure fluctuations in the fuel gallery, but there is a problem that it is necessary to provide a pressure accumulation chamber.

JP 2014-077404

  The present invention has been made in view of the above, and an object of the present invention is to provide a high-pressure supply of liquefied gas fuel supplied from a low-pressure pump in a compression ignition internal combustion engine using liquefied gas fuel as a fuel. By providing a fuel injection system, a compression ignition internal combustion engine, and a control method for the fuel injection system that can reduce the pressure pulsation in the pump, prevent vaporization of the liquefied gas fuel, and stably supply the liquefied gas fuel. is there.

  In order to achieve the above object, a fuel injection system of the present invention comprises a low pressure pump and a high pressure pump, the high pressure pump storing a liquefied gas fuel, and a high pressure chamber connected to the gallery through a communication passage. And an on-off valve provided in the communication passage and a reciprocating plunger provided in the high-pressure chamber, and storing the liquefied gas fuel supplied by the low-pressure pump in the gallery. A fuel injection system configured to suck liquefied gas fuel into the high pressure chamber by opening / closing control of the on-off valve and reciprocating control of the plunger, pressurize the sucked liquefied gas fuel, and discharge the liquefied gas fuel from the high pressure chamber. The gallery is provided with a pressure sensor for detecting the pressure of the liquefied gas fuel and a temperature sensor for detecting the temperature of the liquefied gas fuel to control the fuel injection system. A reference control signal corresponding to an average target pressure of the supply pressure of the low-pressure pump in the control of the supply pressure of the low-pressure pump when the apparatus determines that pressure pulsation has occurred at the pressure detected by the pressure sensor. In addition, a smoothing control signal for generating a correction pressure having a phase opposite to that of the pressure pulsation and smoothing the pressure pulsation is added.

  According to this configuration, when a pressure pulsation of the liquefied gas fuel is generated in the high pressure pump gallery in a fuel injection system used for a compression ignition internal combustion engine using liquefied gas fuel as a fuel, By controlling the supply pressure of the pump, the pressure pulsation amplitude in the gallery is reduced, and the pressure of the liquefied gas fuel in the gallery is equal to or lower than the saturated vapor pressure of the liquefied gas fuel corresponding to the temperature of the liquefied gas fuel at that time. Therefore, the liquefied gas fuel can be supplied stably. In addition, it is possible to suppress the control deviation caused by the pressure pulsation of the gallery that occurs due to the control of the supply pressure of the low-pressure pump.

  In the fuel injection system, when the control device determines that pressure pulsation is generated at the pressure detected by the pressure sensor, the reference control signal is set in the control of the supply pressure of the low pressure pump. Based on the temperature detected by the temperature sensor, the amplitude value of the smoothing control signal is calculated in advance based on the engine speed and fuel injection amount of the compression ignition internal combustion engine equipped with the fuel injection system. When configured to calculate from the set database, the following effects can be obtained.

  According to this configuration, since the reference control signal can be changed in accordance with the temperature of the liquefied gas fuel related to the saturated vapor pressure of the liquefied gas fuel, the average pressure of the liquefied gas fuel in the gallery can be easily adjusted to the saturated vapor pressure. Higher values can be maintained.

  Further, the pressure fluctuation of the liquefied gas fuel in the gallery is related to the amount of fuel discharged from the high-pressure pump per unit time, that is, the injection amount injected into the cylinder, and depends on the engine speed and the fuel injection amount (or load). Since the amplitude value of the smoothing control signal is calculated from a preset database based on the engine speed and fuel injection amount, finer smoothing of pressure pulsation is possible. Thus, the liquefied gas fuel can be supplied more stably while preventing the liquefied gas fuel from being vaporized.

  Alternatively, in the fuel injection system, when the control device determines that pressure pulsation is occurring at the pressure detected by the pressure sensor, the temperature detected by the temperature sensor is the initial value of the reference control signal. Thereafter, the reference control signal is feedback-controlled so that the average value of the pressure detected by the pressure sensor becomes the average target pressure, and the amplitude value of the smoothing control signal is calculated. An initial value is calculated from a preset database based on the engine speed and fuel injection amount of a compression ignition type internal combustion engine equipped with the fuel injection system, and thereafter, the smoothing control signal is When the feedback control is performed so that the amplitude of the pressure detected by the pressure sensor becomes zero, the following effects can be obtained.

  According to this configuration, the initial value of the reference control signal can be changed in accordance with the temperature of the liquefied gas fuel related to the saturated vapor pressure of the liquefied gas fuel, and thereafter, the control shifts to feedback control, so the liquefied gas fuel in the gallery This value can be maintained at a target pressure higher than the saturated vapor pressure more quickly and reliably.

  In addition, by calculating the initial value of the amplitude value of the smoothing control signal from a preset database based on the engine speed and the fuel injection amount, it is possible to perform finer smoothing on the pressure pulsation, After that, since the control shifts to feedback control, the liquefied gas fuel can be supplied more stably while preventing vaporization of the liquefied gas fuel more quickly and reliably.

  In addition, it is preferable to learn the amplitude values of the reference control signal and the smoothing control signal, which have become substantially constant by feedback control, using a learning function, and sequentially update the database.

  In order to achieve the above object, a compression ignition type internal combustion engine of the present invention is a compression ignition type internal combustion engine equipped with the above fuel injection system, and has the same effects as the above fuel injection system. be able to.

  And the control method of the fuel-injection system of this invention for achieving said objective stores the supplied liquefied gas fuel in a gallery, and connects this liquefied gas fuel which connects the said gallery and a high pressure chamber. Fuel provided with a high-pressure pump that sucks into the high-pressure chamber and pressurizes the sucked liquefied gas fuel and discharges it from the high-pressure chamber by opening / closing control of the on-off valve provided in the passage and reciprocating control of the plunger of the high-pressure chamber In the control method of the injection system, in the control of the supply pressure of the low pressure pump that supplies the liquefied gas fuel to the high pressure pump when it is determined that pressure pulsation has occurred inside the gallery, the supply pressure of the low pressure pump A smoothing control signal that generates a correction pressure that is in phase opposite to the pressure pulsation and smoothes the pressure pulsation as a reference control signal corresponding to the average target pressure of A method characterized by plus.

  In the control method of the fuel injection system, when a pressure pulsation is generated in the gallery, the reference control signal is set to the temperature of the liquefied gas fuel in the gallery in the control of the supply pressure of the low pressure pump. And the amplitude value of the smoothing control signal is calculated from a preset database based on the engine speed and fuel injection amount of the compression ignition internal combustion engine equipped with the fuel injection system.

  Further, in the control method of the fuel injection system, when pressure pulsation occurs in the gallery, the initial value of the reference control signal is calculated based on the temperature of the liquefied gas fuel in the gallery, Thereafter, the reference control signal is feedback-controlled so that the average value of the pressure of the liquefied gas fuel in the gallery becomes the average target pressure, and the initial value of the amplitude value of the smoothing control signal is Based on the engine speed and fuel injection amount of a compression ignition type internal combustion engine equipped with the fuel injection system, it is calculated from a preset database, and thereafter the smoothing control signal is liquefied in the gallery. Feedback control is performed so that the amplitude of the pressure of the gas fuel becomes zero.

  According to these methods, the same operational effects as those of the fuel injection system of the compression ignition type internal combustion engine can be obtained.

  According to the fuel injection system, the compression ignition type internal combustion engine, and the control method of the fuel injection system of the present invention, in the fuel injection system used for the compression ignition type internal combustion engine using liquefied gas fuel as the fuel, the liquefaction is performed by the high pressure pump gallery. When pressure pulsation of gas fuel occurs, the pressure of the pulsating gas fuel in the gallery is reduced by controlling the supply pressure of the low pressure pump in consideration of the pressure pulsation, thereby reducing the pressure pulsation amplitude in the gallery. Since the vapor pressure of the liquefied gas fuel can be prevented by preventing the liquefied gas fuel from becoming below the saturated vapor pressure corresponding to the temperature of the liquefied gas fuel at that time, the liquefied gas fuel can be supplied stably. In addition, it is possible to suppress the control deviation caused by the pressure pulsation of the gallery that occurs due to the control of the supply pressure of the low-pressure pump.

It is a figure showing typically an example of composition of a fuel injection system of an embodiment concerning the present invention. It is a figure for demonstrating the control method of the fuel-injection system of embodiment which concerns on this invention. It is a figure which shows typically the structure of the high pressure pump of FIG. 1, and is a figure which shows the state which attracts | sucks fuel from a gallery to a high pressure chamber. It is a figure which shows typically the structure of the high pressure pump of FIG. 1, and is a figure which shows the state which discharges the fuel of a high pressure chamber.

  Hereinafter, a fuel injection system, a compression ignition type internal combustion engine, and a control method for the fuel injection system according to embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a fuel injection system 1 according to an embodiment of the present invention includes a low-pressure pump 12 and a high-pressure pump 10, and fuel F stored in a fuel tank 11 is fed by a low-pressure pump (feed pump) 12. The pressure is increased to about 3 MPa and supplied to the high-pressure pump 10 via the fuel filter 13, and the fuel F is further pressurized by the high-pressure pump 10 to increase the pressure to about 60 MPa to 80 MPa. This high pressure fuel F is accumulated in a common rail 14 and is supplied from the common rail 14 to a fuel injection valve 15 provided in each cylinder of a compression ignition type internal combustion engine (not shown).

  As the fuel F, a liquefied gas fuel (hereinafter referred to as fuel F) such as DME fuel (DME: dimethyl ether) is used. In FIG. 1, four fuel injection valves 15 are shown for convenience. However, since the fuel injection valves 15 are actually provided for each cylinder of the engine, the number of fuel injection valves 15 is the same as the number of engine cylinders. become.

  In this fuel injection system 1, excess fuel F supplied to the high-pressure pump 10 by the low-pressure pump 12 is returned to the fuel tank 11 via the relief valve 21, and the pressure in the common rail 14 is set to a predetermined pressure or less. Therefore, a part of the fuel F in the common rail 14 is returned to the fuel tank 11 via the pressure reducing valve 22 and the safety valve 23. Further, the fuel F remaining in each fuel injection valve 15 without being injected into each cylinder is also returned to the fuel tank 11. In FIG. 1, a return flow path for returning the fuel F from the high-pressure pump 10, the common rail 14, or each fuel injection valve 15 to the fuel tank 11 is indicated by a dotted line.

  Regarding the sensor, a temperature sensor 31 that detects the temperature T in the gallery 10a of the high-pressure pump 10 and a first pressure sensor 32 that detects the pressure P in the gallery 10a are provided in the gallery 10a. A second pressure sensor 33 that detects the pressure supplied from the low pressure pump 12 to the high pressure pump 10 and a third pressure sensor 34 that detects the pressure in the common rail 14 are provided.

  Moreover, as shown in FIG. 1, the control apparatus 40 which controls the fuel-injection system 1 is provided. The control device 40 includes a temperature sensor 31, first to third pressure sensors 32 to 34, an accelerator opening sensor 35, a crank angle sensor 36, a cam angle sensor 37 of a valve mechanism of intake and exhaust valves in each cylinder, and the like. The signals from the various sensors 31 to 37 are received, and the high pressure pump 10, the low pressure pump 12, the common rail 14, or each fuel injection valve 15 is controlled based on these signals. The control device 40 is usually an engine control that performs overall control of the engine and overall control of the vehicle based on signals of various sensors provided in the engine or various sensors provided in a vehicle equipped with the engine. -Built in a control device called a unit (ECU).

  Next, the detailed configuration of the high-pressure pump 10 shown in FIG. 1 will be described with reference to FIGS. 3 and 4. As shown in FIGS. 3 and 4, the high-pressure pump 10 includes a gallery 10a for storing fuel F, a high-pressure chamber 10c connected to the gallery 10a through a communication passage 10d, and an electromagnetic valve ( On-off valve) 10e and a plunger 10b that is provided in the high-pressure chamber 10c and reciprocates.

  The fuel F supplied by the low-pressure pump 12 is stored in the gallery 10a, and the stored fuel F is controlled to open and close the solenoid valve 10e and to reciprocate the plunger 10b (the plunger 10b is driven by the rotating operation of the cam 16). As a result, the fuel is sucked into the high pressure chamber 10c, and the sucked fuel F is pressurized and discharged from the high pressure chamber 10c. The fuel F discharged at a high pressure of about 60 MPa to 80 MPa is supplied to the common rail 14 connected to the fuel injection valve 15. The electromagnetic valve 10e is closed when energized (ON), for example, and opened when demagnetized (OFF).

  The high-pressure pump 10 leaks the fuel F that has flowed into the gap between the check valve 10f that prevents the fuel F from flowing back from the common rail 14 to the high-pressure chamber 10c, and the plunger 10b and the cylinder that houses the check valve 10f. As the fuel Fr, there is provided a leak fuel recovery passage 10g that returns into the gallery 10a, and a seal member 10h that prevents the leaked fuel F from leaking into a crank chamber (not shown) outside the high-pressure pump 10 is provided. Is provided.

  Next, the operation of the high-pressure pump 10 will be described with reference to FIGS. As shown in FIG. 3, when the cam 16 rotates and moves the plunger 10b in the direction in which the inside of the cylinder expands (downward in FIG. 2), the electromagnetic valve 10e is opened and the fuel F is discharged from the gallery 10a. The high-pressure chamber 10c is sucked through the communication passage 10d.

Next, as shown in FIG. 4, when the cam 16 further rotates and moves the plunger 10b in the direction in which the inside of the cylinder contracts (upward in FIG. 3), the electromagnetic valve 10e is closed to increase the pressure. The fuel F in the chamber 10c is discharged to the common rail 14.
The discharge amount of the fuel F to the common rail 14 is performed by so-called prestroke control in which the closing timing of the on-off valve 10e is controlled according to the lift of the cam 16 (prestroke is adjusted).

  That is, in the fuel injection system 1 according to the embodiment of the present invention, the supplied fuel F is stored in the gallery 10a, and the stored fuel F is electromagnetically provided in the communication passage 10d that connects the gallery 10a and the high pressure chamber 10c. A high pressure pump 10 that sucks into the high pressure chamber 10c and pressurizes the sucked fuel F and discharges it from the high pressure chamber 10c by opening / closing timing control of the valve 10e and reciprocation control of the plunger 10b of the high pressure chamber 10c. .

  In the present invention, as shown in FIG. 2, the pressure pulsation ΔPg (t) is generated at the pressure Pg (t) detected by the first pressure sensor 32 during the control of the control device 40 at time t. In the control of the supply pressure Po (t) of the low-pressure pump 12, the pressure pulsation ΔPg (t) is applied to the reference control signal Soa corresponding to the average target pressure Pomt of the supply pressure Po (t) of the low-pressure pump 12. And a smoothing control signal Soc (t) for generating a correction pressure Poc (t) for smoothing the pressure pulsation ΔPg (t).

  That is, when it is determined that the pressure pulsation ΔPg (t) is generated in the pressure Pg (t) in the gallery 10a, the supply pressure Po (t) of the low-pressure pump 12 is changed to the pressure pulsation ΔPg (t in the gallery 10a. ) And a correction pressure Poc (t) having a phase opposite to that of the pressure pulsation ΔPg (t) is generated to control the low pressure pump 12 so that the pressure pulsation ΔPg (t) is reduced. .

  In other words, the control signal So (t) to the low pressure pump 12 is set to So (t) = Soa + Soc (t), and the supply pressure of the low pressure pump 12 is controlled to be Po (t) = Pomt + Poc (t). As a result, the supply pressure (discharge pressure) Po (t) of the low-pressure pump 12 is controlled so that Pg (t)> Ps (T) and ΔPg (t) = small in the pressure in the gallery 10a. To do.

  More specifically, since it is necessary to prevent the liquid fuel F supplied from the fuel tank 11 from changing to a gas state, the pressure Pg (t) in the gallery 10a is related to the temperature T in the gallery 10a. The target supply pressure Pot (t) of the low-pressure pump 12 during control at time t is set so that the set value Pa (T) exceeds the saturated vapor pressure Ps (T) of the fuel F, but the pressure pulsation ΔPg ( When the amplitude of t) increases, the pressure Pg (t) in the gallery 10a temporarily becomes lower than the saturated vapor pressure Ps (T) and may vaporize. By controlling the supply pressure Po (t), a correction pressure Poc (t), which is a component having an opposite phase to the phase of the pressure pulsation ΔPg (t), is added to suppress the pressure pulsation ΔPg (t).

  Note that whether or not the pressure pulsation ΔPg (t) has occurred is determined, for example, when the amplitude of ΔPg (t) exceeds a preset amplitude threshold or during a preset period of ΔPg (t). This can be easily performed by assuming that the pressure pulsation ΔPg (t) is generated when the standard deviation exceeds a preset standard deviation threshold.

  More specifically, as shown by B (thick line) in FIG. 2, the control device 40 controls the supply pressure Po (t) of the low-pressure pump 12 to be a reference control signal that serves as a reference for the control signal So (t). Soa is calculated based on the temperature T detected by the temperature sensor 31. At the same time, the amplitude value ΔSoc of the smoothing control signal Soc (t) is determined from the engine speed Ne and the fuel injection amount q (or load Q) of the compression ignition internal combustion engine (not shown) equipped with the fuel injection system 1. Based on the above, it is configured to calculate from a preset database. For example, where f is the frequency and θ is the phase, So (t) = Soa + Soc (t) = Soa + ΔSoc × sin (2πft + θ).

  As a result, the reference control signal Soa is changed in correspondence with the temperature T of the fuel F related to the saturated vapor pressure Ps (T) of the fuel F, so that the average value Pgm that is the average pressure of the fuel F in the gallery 10a. Can be easily maintained at a value higher than the saturated vapor pressure Ps.

  The pressure pulsation ΔPg (t) of the fuel F in the gallery 10a is related to the amount of fuel discharged from the high-pressure pump 10 per unit time, that is, the injection amount injected into the cylinder, and the engine speed Ne and fuel injection. Since the smoothing control signal Soc (t) is calculated from a preset database based on the engine speed Ne and the fuel injection amount q, the pressure pulsation ΔPg (t ), The fuel F can be supplied more stably while preventing the fuel F from being vaporized.

  Alternatively, when the control device 40 determines that the pressure pulsation ΔPg (t) is generated at the pressure Pg (t) detected by the first pressure sensor 32, as shown by C (dotted line) in FIG. The initial value Soti of the reference control signal Soa is calculated based on the temperature T detected by the temperature sensor 31, and thereafter, the reference control signal Soa is calculated as an average value Pgm of the pressure Pg (t) detected by the first pressure sensor 32. Is controlled so as to become the set value Pa (T) that becomes the average target pressure, and the initial value ΔSoc of the amplitude value ΔSoc of the smoothing control signal Soc (t) is used as the compression ignition equipped with the fuel injection system 1. Is calculated from a preset database based on the engine speed Ne and the fuel injection amount q of the internal combustion engine, and thereafter, the smoothing control signal Soc (t) is used as the first pressure sensor. The amplitude of 2 in detected pressure Pg (t) is configured to feedback control so as to zero.

  As a result, the initial value Soai of the reference control signal Soa corresponding to the average of the target value control signal Sot is changed in correspondence with the temperature T of the fuel F related to the saturated vapor pressure Ps (T) of the fuel F. Then, since the control shifts to feedback control, the average pressure Fgm of the fuel F in the gallery 10a is set to a set value Pa (T) higher than the saturated vapor pressure Ps (T) more quickly and surely. The pressure Fgm can be maintained at the set value Fa (T).

  Further, the initial value ΔSoci of the amplitude value ΔSoc of the smoothing control signal Soc (T) is calculated from a preset database based on the engine speed Ne and the fuel injection amount q, and further, the amplitude is determined by feedback control. By optimizing the value ΔSoc, the pressure pulsation ΔPg (t) can be smoothed more finely, and the fuel F can be supplied more stably while preventing vaporization of the fuel F more quickly and reliably. It becomes like this.

  When the learning function is used to learn the reference control signal Soa and the smoothing control signal Soc that have become substantially constant by feedback control, and it is determined that the previous pressure pulsation ΔPg (t) has occurred. It is preferable that the initial values Soai and ΔSoci used in the above are replaced with the final values Soa and ΔSoc of the current control to update the database sequentially.

  In the control method for the fuel injection system according to the embodiment of the present invention, the low pressure pump that supplies the fuel F to the high pressure pump 10 when it is determined that the pressure pulsation ΔPg (t) is generated inside the gallery 10a. In the control of the supply pressure Po (t) of 12, the target value control signal Sot corresponding to the average target pressure Pomt of the supply pressure Po (t) of the low pressure pump 12 is set to the reference control signal Soa and the pressure pulsation ΔPg (t). And a smoothing control signal Soc (t) for generating a correction pressure Poc (t) for smoothing the pressure pulsation ΔPg (t).

  Further, when pressure pulsation is generated in the gallery 10a, the reference control signal Soa is calculated based on the temperature T of the fuel F in the gallery 10a in the control of the supply pressure Po (t) of the low-pressure pump 12. At the same time, the amplitude value ΔSoc of the smoothing control signal Soc (t) is obtained from a preset database based on the engine speed Ne and the fuel injection amount q of the compression ignition internal combustion engine equipped with the fuel injection system 1. calculate.

  Alternatively, when pressure pulsation occurs in the gallery 10a, the initial value Soai of the reference control signal Soa is calculated based on the temperature T of the fuel F in the gallery 10a, and thereafter, the reference control signal Soa is calculated. The feedback control is performed such that the average value Pgm of the pressure Pg (t) of the fuel F in the gallery 10a becomes the average target pressure Pomt, and the initial value ΔSoc of the amplitude value ΔSoc of the smoothing control signal Soc is used as the fuel injection. Based on the engine speed Ne and the fuel injection amount q of the compression ignition type internal combustion engine equipped with the system 1, it is calculated from a preset database, and thereafter, the amplitude value ΔSoc of the smoothing control signal Soc is obtained as a gallery. Feedback control is performed so that the amplitude of the pressure pulsation ΔPg (t) of the pressure Pg (t) of the fuel F within 10a becomes zero.

  A compression ignition type internal combustion engine according to an embodiment of the present invention is provided with the fuel injection system 1 described above. Thereby, there can exist an effect similar to said fuel-injection system 1. FIG.

  According to the fuel injection system 1, the compression ignition internal combustion engine, and the control method for the fuel injection system configured as described above, in the fuel injection system 1 used for the compression ignition internal combustion engine using liquefied gas fuel as the fuel F, etc. When the pressure pulsation of the fuel F is generated in the tenth gallery 10a, the pressure pulsation ΔPg (t) in the gallery 10a is controlled by controlling the supply pressure Po (t) of the low-pressure pump 12 in consideration of the pressure pulsation. To prevent the pressure Pg (t) of the fuel F in the gallery 10a from becoming equal to or lower than the saturated vapor pressure Ps (T) of the fuel F corresponding to the temperature T of the fuel F at that time. Therefore, the fuel F can be supplied stably. Further, it is possible to suppress a control deviation caused by the pressure pulsation ΔPg (t) of the gallery 10a, which is caused by the control of the supply pressure Po (t) of the low pressure pump 12.

DESCRIPTION OF SYMBOLS 1 Fuel injection system 10 High pressure pump 10a Gallery 10b Plunger 10c High pressure chamber 10d Connection passage 10e Electromagnetic valve (open / close valve)
10f Check valve 10g Leak fuel recovery flow path 11 Fuel tank 12 Low pressure pump (feed pump)
14 common rail 15 fuel injection valve 16 cam 31 temperature sensor 32 first pressure sensor 40 control device F fuel (liquefied gas fuel)
Pa set value (value exceeding saturated vapor pressure)
Pg (t) Pressure in the gallery Pgm Average value in the gallery Po (t) Low pressure pump supply pressure Poc (t) Correction pressure Pomt Average target pressure Pot (t) Target supply pressure Ps (T) Saturated steam pressure So (t ) Control signal Soa Reference control signal Soai Initial value Soc (t) of smoothing control signal T Temperature ΔPg (t) in smoothing pressure pulsation ΔSoc Amplitude value ΔSoci of smoothing control signal Initial amplitude value

Claims (7)

It has a low-pressure pump and a high-pressure pump,
The high-pressure pump includes a gallery for storing liquefied gas fuel, a high-pressure chamber connected to the gallery through a communication passage, an on-off valve provided in the communication passage, and a plunger that is provided in the high-pressure chamber and reciprocates. The liquefied gas fuel supplied by the low-pressure pump is stored in the gallery, and the stored liquefied gas fuel is sucked into the high-pressure chamber by opening / closing control of the on-off valve and reciprocating control of the plunger. In the fuel injection system configured to pressurize and discharge the sucked liquefied gas fuel from the high pressure chamber,
A pressure sensor for detecting the pressure of the liquefied gas fuel in the gallery and a temperature sensor for detecting the temperature of the liquefied gas fuel;
A control device for controlling the fuel injection system;
When it is determined that pressure pulsation has occurred at the pressure detected by the pressure sensor,
In the control of the supply pressure of the low-pressure pump, a reference pressure signal corresponding to the average target pressure of the supply pressure of the low-pressure pump is generated with a correction pressure that is in phase opposite to the pressure pulsation and smoothes the pressure pulsation. A fuel injection system configured to add a control signal for smoothing. The control device is
When it is determined that pressure pulsation has occurred at the pressure detected by the pressure sensor,
In the control of the supply pressure of the low-pressure pump, the reference control signal is calculated based on the temperature detected by the temperature sensor, and the amplitude value of the smoothing control signal is calculated by a compression ignition type equipped with the fuel injection system. The fuel injection system according to claim 1, wherein the fuel injection system is configured to calculate from a preset database based on an engine speed and a fuel injection amount of the internal combustion engine. The control device is
When it is determined that pressure pulsation has occurred at the pressure detected by the pressure sensor,
The initial value of the reference control signal is calculated based on the temperature detected by the temperature sensor, and thereafter, the reference control signal is calculated so that the average value of the pressure detected by the pressure sensor becomes the average target pressure. With feedback control,
The initial value of the amplitude value of the smoothing control signal is calculated from a preset database based on the engine speed and fuel injection amount of a compression ignition internal combustion engine equipped with the fuel injection system, and thereafter The fuel injection system according to claim 1, wherein the smoothing control signal is feedback-controlled so that an amplitude of a pressure detected by the pressure sensor becomes zero.   A compression ignition type internal combustion engine equipped with the fuel injection system according to any one of claims 1 to 3. The supplied liquefied gas fuel is stored in a gallery, and the stored liquefied gas fuel is controlled by opening / closing control of an on-off valve provided in a communication passage connecting the gallery and the high pressure chamber and reciprocating control of a plunger of the high pressure chamber. In a control method of a fuel injection system including a high-pressure pump that sucks into the high-pressure chamber, pressurizes the sucked liquefied gas fuel, and discharges the liquefied gas fuel from the high-pressure chamber.
When it is determined that pressure pulsation has occurred inside the gallery,
In the control of the supply pressure of the low-pressure pump that supplies the liquefied gas fuel to the high-pressure pump, a reference control signal corresponding to the average target pressure of the supply pressure of the low-pressure pump has an opposite phase to the pressure pulsation and the pressure pulsation A control method for a fuel injection system, characterized by adding a smoothing control signal for generating a correction pressure for smoothing the fuel. When pressure pulsation occurs inside the gallery,
In controlling the supply pressure of the low-pressure pump, the reference control signal is calculated based on the temperature of the liquefied gas fuel in the gallery, and the amplitude value of the smoothing control signal is compressed by the fuel injection system. 6. The control method for a fuel injection system according to claim 5, wherein the control method is calculated from a preset database based on the engine speed and fuel injection amount of the ignition type internal combustion engine. When pressure pulsation occurs inside the gallery,
An initial value of the reference control signal is calculated based on the temperature of the liquefied gas fuel in the gallery, and thereafter, the reference control signal is calculated as an average value of the pressure of the liquefied gas fuel in the gallery. And feedback control to become
The initial value of the amplitude value of the smoothing control signal is calculated from a preset database based on the engine speed and fuel injection amount of a compression ignition internal combustion engine equipped with the fuel injection system, and thereafter 6. The fuel injection system control method according to claim 5, wherein the smoothing control signal is feedback-controlled so that the amplitude of the pressure of the liquefied gas fuel in the gallery becomes zero.

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