JP2019065765A - Fuel pump control device for internal combustion engine - Google Patents

Abstract

To shorten the time from switching the number of fuel pumps to be driven to settling an actual fuel pressure near a target fuel pressure.SOLUTION: An electronic control unit performs feedback control on first and second high pressure fuel pumps. During twin drive (YES in step S22), the electronic control unit does not update an integration term Isg for single drive but performs the feedback control using an integration term Itw for twin drive. When the twin drive is switched to single drive, the electronic control unit performs the feedback control using the integration term Itw for single drive in the end of the previous single drive. During single drive (NO in step S22), the electronic control unit does not update the integration term Itw for twin drive but performs feedback using the integration term Isg for single drive. When the single drive is switched to the twin drive, the electronic control unit performs the feedback control using the integration term Itw for twin drive in the end of the previous twin drive.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel pump control device applied to an internal combustion engine.

  The internal combustion engine of Patent Document 1 includes a first high-pressure fuel pump and a second high-pressure fuel pump that further boosts and discharges the fuel pressure-fed from the feed pump. The first high pressure fuel pump discharges the fuel to the first high pressure delivery pipe, and the second high pressure fuel pump discharges the fuel to the second high pressure delivery pipe. Also, the first high pressure delivery pipe and the second high pressure delivery pipe communicate with each other by the connection pipe. Further, each high-pressure fuel pump of the internal combustion engine of Patent Document 1 is controlled by a fuel pump control device. The fuel pump control device drives either or both of the first high pressure fuel pump and the second high pressure fuel pump based on the required discharge amounts of the first high pressure fuel pump and the second high pressure fuel pump. Switch.

Unexamined-Japanese-Patent No. 2006-37920

  The fuel pump control device as disclosed in Patent Document 1 is feedback-controlled so that the actual fuel pressure of the fuel discharged from the first high pressure fuel pump and the second high pressure fuel pump approaches the target fuel pressure. As described above, the number of high pressure pumps being driven is different between the state in which both the first high pressure fuel pump and the second high pressure fuel pump are being driven and the state in which only one is being driven. And the ease with which fuel pressure changes (response) also differ. Nevertheless, if feedback control is performed using the same equation or the like, the actual fuel pressure may change significantly when the number of actuations of the fuel pump is switched. As described above, when the actual fuel pressure largely changes, it takes a long time until the actual fuel pressure converges to the vicinity of the target fuel pressure after switching the number of driving of the fuel pump. That is, the controllability of the actual fuel pressure is degraded.

  In order to solve the above-mentioned problems, according to the present invention, a first fuel pump for pressurizing and discharging fuel, a first fuel passage through which the fuel discharged by the first fuel pump flows, and a first fuel passage are supplied. A first fuel injection valve for injecting fuel, a second fuel pump for boosting and discharging the fuel, a second fuel passage through which the fuel discharged by the second fuel pump flows, and a supply from the second fuel passage Second fuel injection valve for injecting the fuel to be used, a connection passage connecting the first fuel passage and the second fuel passage, any one of the first fuel passage, the second fuel passage, and the connection passage A fuel pump control device applied to an internal combustion engine including a fuel pressure sensor for detecting a fuel pressure of the fuel pump, wherein both the first fuel pump and the second fuel pump are driven according to the operating condition of the internal combustion engine Drive twin or before A pump switching unit for switching a single drive for driving any one of the first fuel pump and the second fuel pump; and so that the actual fuel pressure detected by the fuel pressure sensor approaches the target fuel pressure when the twin drive is performed. The first fuel pump and the second fuel pump are feedback-controlled using a proportional term and an integral term for twin drive, so that the actual fuel pressure detected by the fuel pressure sensor approaches the target fuel pressure when the single drive is performed. And a pump control unit that performs feedback control of the first fuel pump or the second fuel pump using a proportional term and an integral term for single drive, and the pump control unit performs the twin drive. When switching from twin drive to single drive without updating the integral term for single drive, the end of the previous single drive The feedback control is performed using the integral term for single drive, and when single drive is performed, the integral term for twin drive is not updated, and when the single drive is switched to twin drive, the previous twin drive is ended. Feedback control is performed using the integral term for twin driving.

  According to the above configuration, the integral term for single drive does not reflect the state at the time of twin drive, and the integral term for twin drive does not reflect the state at the time of single drive. Therefore, a difference in fuel pressure response resulting from the difference in the number of driving of the fuel pump is not reflected in each integral term. Therefore, it is possible to calculate an appropriate integral term excluding the influence of each other as the integral term for single drive and the integral term for twin drive. Further, at the time of switching between single drive and twin drive, instead of integrating the deviation again to calculate the integral term, the integral term with the same number of fuel pump actuations at the previous time is continuously used. Therefore, when the number of driving of the fuel pump is switched, a sudden change in the actual fuel pressure is suppressed, and the time until the actual fuel pressure converges to the target fuel pressure can be shortened.

  In the above invention, the pump control unit calculates a proportional term using a proportional term gain common to the twin drive and the single drive, and uses an integral term gain common to the twin drive and the single drive. An integral term for single drive and an integral term for twin drive may be calculated.

  According to the above configuration, in the case of single drive, an excessively large absolute value is not calculated as a proportional term or an integral term for single drive. Therefore, it is possible to reduce the degree of overshoot or undershoot that occurs in single drive.

  In the above invention, in addition to the feedback control, the pump control unit uses a feedforward term based on a required injection amount of the first fuel injection valve and the second fuel injection valve to use the first fuel pump and the first fuel pump. The feedforward control of the second fuel pump is performed, and the pump control unit sets the feedforward term gain in the single drive to a value larger than 1 and not more than 2 times the feedforward term gain in the twin drive. Do.

  According to the above configuration, the poor responsiveness of the fuel pressure at the single drive can be compensated by making the feed forward term gain at the single drive larger than that at the twin drive. Therefore, in single drive, it is possible to shorten the time until the actual fuel pressure converges to the target fuel pressure.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of an internal combustion engine. The flowchart regarding the switching determination processing of a twin drive and a single drive. The flowchart regarding control processing of a high pressure fuel pump.

Hereinafter, an embodiment in which the present invention is applied to a V-type six-cylinder internal combustion engine 10 will be described according to the drawings.
As shown in FIG. 1, an electric feed pump 12 is disposed in a fuel tank 11 of the internal combustion engine 10. A low pressure fuel pipe 15 is connected to the feed pump 12. The feed pump 12 pressure-feeds the fuel in the fuel tank 11 to the low pressure fuel pipe 15. A filter 13 for filtering foreign matter contained in the fuel is provided in a portion of the low pressure fuel pipe 15 in the fuel tank 11.

  The low pressure fuel piping 15 is branched into a first low pressure fuel piping 16 and a second low pressure fuel piping 17 outside the fuel tank 11. The first low pressure fuel pipe 16 further branches into a first branch pipe 16a and a second branch pipe 16b. At the downstream end of the first branch pipe 16a, a first low pressure delivery pipe 21 for storing a fixed amount of fuel pressure-fed from the feed pump 12 is connected. Three first port injection valves 22 are connected to the first low pressure delivery pipe 21. Each first port injection valve 22 injects fuel into an intake port of a cylinder of one of the cylinders of the V-type arrangement. The first low pressure delivery pipe 21 is provided with a low pressure side fuel pressure sensor 23 for detecting the actual fuel pressure FPL in the first low pressure delivery pipe 21.

  At the downstream end of the second branch pipe 16b, a second low pressure delivery pipe 25 for storing a fixed amount of fuel pressure-fed from the feed pump 12 is connected. Three second port injection valves 26 are connected to the second low pressure delivery pipe 25. Each second port injection valve 26 injects fuel into the intake port of the cylinder of the other bank of the cylinders of the V-type arrangement.

  The second low pressure fuel pipe 17 is further branched into a first branch pipe 17a and a second branch pipe 17b. The downstream end of the first branch pipe 17a is connected to a first high-pressure fuel pump 31 that further boosts and discharges the fuel pressure-fed from the feed pump 12. The first high pressure fuel pump 31 has a substantially cylindrical cylinder 32 in communication with the first branch pipe 17 a of the second low pressure fuel pipe 17. In the cylinder 32, a cylindrical plunger 33 capable of reciprocating the cylinder 32 in the axial direction is disposed. A pressure chamber R1 for pressurizing the fuel is defined by the front end surface (upper end surface in FIG. 1) of the plunger 33 and the inner wall surface of the cylinder 32. A cam follower 34 is provided at the end of the plunger 33 (the lower end in FIG. 1). The cam follower 34 is movable in the axial direction of the cylinder 32 and is urged to abut on the outer peripheral surface of the cam 35. The cam 35 rotates in response to the rotation of the crankshaft of the internal combustion engine 10, and the cam follower 34 transmits the rotation of the cam 35 to the plunger 33 as an axial movement of the cylinder 32. That is, the plunger 33 reciprocates in the cylinder 32 according to the outer peripheral shape of the cam 35.

  An electromagnetic spill valve 36 is provided at a connecting portion of the pressure chamber R1 in the cylinder 32 and the first branch pipe 17 a of the second low pressure fuel pipe 17. The electromagnetic spill valve 36 is a normally open valve that closes when energized. The electromagnetic spill valve 36 permits the flow of fuel between the first branch pipe 17a and the pressurizing chamber R1 when the valve is opened, and blocks the flow of the fuel between the two when the valve is closed.

  A first high pressure delivery pipe 41 for storing a predetermined amount of fuel discharged from the first high pressure fuel pump 31 is connected to the pressurizing chamber R1 of the first high pressure fuel pump 31 via a first high pressure fuel pipe 37 ing. Three first in-cylinder injection valves 42 are connected to the first high pressure delivery pipe 41. Each first in-cylinder injection valve 42 injects fuel into a cylinder of one of the cylinders of the V-type arrangement. The first high pressure delivery pipe 41 is provided with a high pressure side fuel pressure sensor 43 for detecting the actual fuel pressure FPH in the first high pressure delivery pipe 41. In this embodiment, the first high pressure fuel pipe 37 and the first high pressure delivery pipe 41 correspond to a first fuel passage.

  A check valve 38 is provided in the middle of the first high pressure fuel pipe 37. The check valve 38 opens when the fuel pressure in the pressure chamber R1 of the cylinder 32 becomes higher than the fuel pressure in the first high pressure delivery pipe 41 by a prescribed pressure or more, and the first high pressure fuel pump 31 The fuel is allowed to be discharged to the delivery pipe 41. That is, the check valve 38 regulates the flow of fuel from the first high pressure delivery pipe 41 to the first high pressure fuel pump 31.

  The downstream end of the second branch pipe 17b is connected to a second high-pressure fuel pump 51 that further boosts and discharges the fuel pressure-fed from the feed pump 12. The second high-pressure fuel pump 51 has a substantially cylindrical cylinder 52 communicating with the second branch pipe 17 b of the second low-pressure fuel pipe 17. In the cylinder 52, a cylindrical plunger 53 capable of reciprocating the cylinder 52 in the axial direction is disposed. A pressure chamber R2 for pressurizing the fuel is defined by the front end surface (upper end surface in FIG. 1) of the plunger 53 and the inner wall surface of the cylinder 52. A cam follower 54 is provided at the end of the plunger 53 (the lower end in FIG. 1). The cam follower 54 is movable in the axial direction of the cylinder 52, and is urged to abut on the outer peripheral surface of the cam 55. The cam 55 rotates in response to the rotation of the crankshaft of the internal combustion engine 10, and the cam follower 54 transmits the rotation of the cam 55 to the plunger 53 as an axial movement of the cylinder 52. That is, the plunger 53 reciprocates in the cylinder 52 in accordance with the outer peripheral shape of the cam 55.

  An electromagnetic spill valve 56 is provided at a connection portion between the pressurizing chamber R2 in the cylinder 52 and the second branch pipe 17b of the second low pressure fuel pipe 17. The electromagnetic spill valve 56 is a normally open valve that closes when energized. The electromagnetic spill valve 56 permits the flow of fuel between the second branch pipe 17b and the pressurizing chamber R2 when the valve is opened, and blocks the flow of the fuel between the two when the valve is closed.

  A second high pressure delivery pipe 61 for storing a predetermined amount of fuel discharged from the second high pressure fuel pump 51 is connected to the pressurizing chamber R2 of the second high pressure fuel pump 51 via a second high pressure fuel pipe 57 ing. Three second in-cylinder injection valves 62 are connected to the second high pressure delivery pipe 61. Each second in-cylinder injection valve 62 injects fuel into a cylinder of the other bank of the cylinders of the V-type arrangement. In this embodiment, the second high pressure fuel pipe 57 and the second high pressure delivery pipe 61 correspond to a second fuel passage.

  In the middle of the second high pressure fuel pipe 57, a check valve 58 is provided. The check valve 58 opens when the fuel pressure in the pressure chamber R2 of the cylinder 52 becomes higher than the fuel pressure in the second high pressure delivery pipe 61 by a prescribed pressure or more, and the second high pressure fuel pump 51 The fuel is allowed to be discharged to the delivery pipe 61. That is, the check valve 58 regulates the flow of fuel from the second high pressure delivery pipe 61 to the second high pressure fuel pump 51.

  A return pipe 64 is connected to the second high pressure delivery pipe 61 via a return valve 63. The return pipe 64 extends to the inside of the fuel tank 11. The return valve 63 opens when the fuel pressure in the second high pressure delivery pipe 61 becomes equal to or higher than a predetermined pressure. By opening the return valve 63, the fuel in the second high pressure delivery pipe 61 is returned to the fuel tank 11 via the return pipe 64.

  The first high pressure fuel pipe 37 and the second high pressure fuel pipe 57 are connected by the connection passage 66. That is, the fuel in the first high pressure fuel pipe 37 and the first high pressure delivery pipe 41, and the fuel in the second high pressure fuel pipe 57 and the second high pressure delivery pipe 61 can move back and forth. Therefore, the actual fuel pressures FPH in the first high pressure delivery pipe 41, the second high pressure delivery pipe 61, and the connection passage 66 are all substantially the same.

  The internal combustion engine 10 configured as described above is controlled by the electronic control unit 70. The electronic control unit 70 includes a central processing unit 71 (CPU) that executes programs and calculates various numerical values, a non-volatile ROM 72 storing necessary programs and maps for numerical calculation, and the like when executing programs and the like. It is a computer having a volatile RAM 73 or the like in which data is temporarily stored.

  The actual fuel pressure FPL detected by the low pressure side fuel pressure sensor 23 described above is input to the electronic control unit 70 as a low pressure side actual fuel pressure signal. Further, the actual fuel pressure FPH detected by the high pressure side fuel pressure sensor 43 is input to the electronic control unit 70 as a high pressure side actual fuel pressure signal. Further, signals from an accelerator sensor 81, a vehicle speed sensor 82 and a throttle sensor 83 provided in the vehicle are input to the electronic control unit 70. The accelerator sensor 81 detects the depression Acc of the accelerator pedal provided in the vehicle, and outputs it to the electronic control unit 70 as a depression amount signal. The vehicle speed sensor 82 detects the vehicle speed SP of the vehicle and outputs it to the electronic control unit 70 as a vehicle speed signal. The throttle sensor 83 detects the throttle opening degree TA of the throttle valve provided in the intake passage of the internal combustion engine 10, and outputs it to the electronic control unit 70 as a throttle opening degree signal. The electronic control unit 70 also includes a crank angle sensor for detecting the rotational angle of the crankshaft, an air flow meter flowing through the intake passage, an exhaust air / fuel ratio sensor for detecting the air fuel ratio (oxygen partial pressure) of the exhaust in the exhaust passage, etc. And the electronic control unit 70 grasps the operating condition of the internal combustion engine 10.

  The electronic control unit 70 calculates a required injection amount which is a required value of the fuel injected from each of the first port injection valves 22 and each of the second port injection valves 26 based on the signals from the various sensors described above. Then, the electronic control unit 70 outputs an operation signal MSp of the injection valve corresponding to the required injection amount to each first port injection valve 22 and each second port injection valve 26. Each first port injection valve 22 and each second port injection valve 26 inject fuel in a valve opening time according to the operation signal MSp.

  Further, the electronic control unit 70 also calculates the required injection amount, which is the required value of the fuel injected from each of the first in-cylinder injection valve 42 and the second in-cylinder injection valve 62 based on the signals from the various sensors described above. calculate. Then, the electronic control unit 70 controls the operation signals MSd of the first in-cylinder injection valves 42 and the second in-cylinder injection valves 62 according to the required injection amount to the first in-cylinder injection valves 42 and the second cylinders. It outputs to the inner injection valve 62. Each first in-cylinder injection valve 42 and each second in-cylinder injection valve 62 inject fuel in a valve opening time according to the operation signal MSd.

  The electronic control unit 70 outputs an operation signal MSf of the feed pump 12 based on the actual fuel pressure FPL detected by the low pressure side fuel pressure sensor 23. When the actual fuel pressure FPL is lower than the target fuel pressure determined according to the operating state of the internal combustion engine 10, the electronic control unit 70 controls the rotational speed of the feed pump 12 to be high. In addition, the electronic control unit 70 controls the feed pump 12 so that the rotational speed of the feed pump 12 decreases or stops when the actual fuel pressure FPL is higher than a predetermined target fuel pressure.

  The electronic control unit 70 performs feedback control of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 so that the actual fuel pressure FPH approaches the target fuel pressure determined according to the operating state of the internal combustion engine 10. That is, the electronic control unit 70 functions as a pump control unit. In this embodiment, the electronic control unit 70 uses a proportional term calculated based on the deviation between the actual fuel pressure FPH and the target fuel pressure, and an integral term calculated based on an integrated value obtained by integrating the deviation between the actual fuel pressure FPH and the target fuel pressure. Based on the above, PI control of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 is performed.

  Further, the electronic control unit 70 performs feedforward control of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 according to the required injection amount of the first in-cylinder injection valve 42 and the second in-cylinder injection valve 62. Do. Specifically, the electronic control unit 70 sets the first high pressure fuel pump 31 and the first high pressure fuel pump 31 so that the feedforward term FF becomes larger as the required injection amount of the first in-cylinder injection valve 42 and the second in-cylinder injection valve 62 increases. The second high pressure fuel pump 51 is controlled.

  The electronic control unit 70 sets the first high pressure based on the depression amount Acc indicated by the signal from the accelerator sensor 81, the vehicle speed SP indicated by the signal from the vehicle speed sensor 82, and the throttle opening degree TA indicated by the signal from the throttle sensor 83. The twin drive or single drive of the fuel pump 31 and the second high pressure fuel pump 51 is switched. That is, the electronic control unit 70 functions as a pump switching unit. The twin drive is a drive mode for driving both the first high pressure fuel pump 31 and the second high pressure fuel pump 51, and the single drive is any one of the first high pressure fuel pump 31 and the second high pressure fuel pump 51. Drive mode to stop the other. In this embodiment, when switching from twin drive to single drive, the electronic control unit 70 stops the high-pressure fuel pump different from the one stopped at the previous single drive.

  The electronic control unit 70 outputs an operation signal MSh1 reflecting the feedback control (PI control), feedforward control, and twin drive or single drive to the electromagnetic spill valve 36 of the first high-pressure fuel pump 31. The valve opening timing of the electromagnetic spill valve 36 is controlled according to the operation signal MSh1. Specifically, when the actual fuel pressure FPH is increased, the electromagnetic spill valve 36 is controlled so that the valve opening time when the plunger 33 is moved to the pressurizing chamber R1 becomes short. Further, the electromagnetic spill valve 36 is controlled to open when the first high pressure fuel pump 31 is stopped.

  Similarly, the electronic control unit 70 outputs an operation signal MSh2 reflecting the feedback control (PI control), feedforward control, and twin drive or single drive to the electromagnetic spill valve 56 of the second high pressure fuel pump 51. Do. The valve opening timing of the electromagnetic spill valve 56 is controlled in accordance with the operation signal MSh2. Specifically, when the actual fuel pressure FPH is increased, the electromagnetic spill valve 56 is controlled so that the valve opening time when the plunger 53 is moved to the pressurizing chamber R2 becomes short. Also, the electromagnetic spill valve 56 is controlled to open when the second high pressure fuel pump 51 is stopped.

  Next, switching determination processing of twin drive and single drive by the electronic control unit 70 (pump switching unit) will be described. Note that this switching determination process is repeatedly executed every predetermined control cycle until the operation of the internal combustion engine 10 is ended after the internal combustion engine 10 is started.

  As shown in FIG. 2, when the switching determination process is performed, the electronic control unit 70 executes the process of step S11. In step S11, the electronic control unit 70 determines whether the elapsed time T after the internal combustion engine 10 is started is equal to or longer than a predetermined time Tx. The predetermined time Tx is, for example, tens of seconds to tens of seconds. Immediately after the internal combustion engine 10 starts, the operation of the internal combustion engine 10 is unstable, and a relatively large amount of fuel is injected to ensure that the internal combustion engine 10 is operated. That is, the required injection amount of the first in-cylinder injection valve 42 and the second in-cylinder injection valve 62 is large, and the load of the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 is also large. By the process of step S11, it is determined whether the load of the first high pressure fuel pump 31 or the second high pressure fuel pump 51 immediately after the start of the internal combustion engine 10 is large. If it is determined in step S11 that the elapsed time T is less than the predetermined time Tx (NO in step S11), the process of the electronic control unit 70 proceeds to step S17. On the other hand, when it is determined in step S11 that the elapsed time T is equal to or longer than the predetermined time Tx (YES in step S11), the process of the electronic control unit 70 proceeds to step S12.

  In step S12, the electronic control unit 70 determines whether the internal combustion engine 10 is in an idle state. In this embodiment, conditions such as that the depression amount Acc detected by the accelerator sensor 81 is zero and the engine speed of the internal combustion engine 10 is less than or equal to a predetermined speed (several hundreds to a few hundreds rpm) are satisfied. At this time, it is determined that the internal combustion engine 10 is in an idle state. If it is determined that the internal combustion engine 10 is not in the idle state (NO in step S12), the process of the electronic control unit 70 proceeds to step S17. If it is determined that the internal combustion engine 10 is in the idle state (YES in step S12), the process of the electronic control unit 70 proceeds to step S13.

  In step S13, the electronic control unit 70 determines whether the vehicle speed SP detected by the vehicle speed sensor 82 is less than a predetermined vehicle speed SPx. The predetermined vehicle speed SPx is several kilometers per hour to several tens of kilometers per hour. If it is determined that the vehicle speed SP is equal to or higher than the predetermined vehicle speed SPx (NO in step S13), the control of the electronic control unit 70 proceeds to step S17. When it is determined that the vehicle speed SP is less than the predetermined vehicle speed SPx (YES in step S13), the control of the electronic control unit 70 proceeds to step S14.

  In step S14, the electronic control unit 70 determines whether the engine load factor KL is less than or equal to a predetermined load factor KLx. In this embodiment, the electronic control unit 70 calculates the engine load factor KL in accordance with the throttle opening degree TA detected by the throttle sensor 83. Specifically, when the opening degree of the throttle valve is the smallest (in the fully closed state), the engine load factor KL is zero%, and when the opening degree of the throttle valve is the largest (in the fully open state) the engine load The rate KL is 100%. The predetermined load factor KLx is, for example, 20 to 30%. If the engine load factor KL exceeds the predetermined load factor KLx (NO in step S14), the process of the electronic control unit 70 proceeds to step S17. If the engine load factor KL is less than or equal to the predetermined load factor KLx (YES in step S14), the process of the electronic control unit 70 proceeds to step S15.

  In step S15, the electronic control unit 70 determines whether or not the feedforward term FFtw during twin drive used in feedforward control of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 is equal to or less than a predetermined value FFx. Determine if The feedforward term FFtw in twin drive will be described later.

  Here, when the feedforward term FF is large in the present embodiment, the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 are controlled such that the actual fuel pressure FPH is largely increased per unit time. That is, the larger the feed forward term FF, the greater the burden on the first high pressure fuel pump 31 and the second high pressure fuel pump 51. Further, while this load is shared by both the first high pressure fuel pump 31 and the second high pressure fuel pump 51 in the twin drive mode, the first high pressure fuel pump 31 and the second high pressure fuel pump in the single drive mode. Only one of the 51 will be responsible. The predetermined value FFx is not a heavy load if both the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 are being driven, but is large if only one of them is being driven. It is set to a value that will be a burden. The predetermined value FFx can be obtained in advance by performing a test or simulation.

  When it is determined in step S15 that the feedforward term FFtw in twin drive exceeds the predetermined value FFx (NO in step S15), the processing of the electronic control unit 70 shifts to step S17. If it is determined that the feedforward term FFtw in twin drive is equal to or less than the predetermined value FFx (YES in step S15), the process of the electronic control unit 70 proceeds to step S16.

  In step S16, the electronic control unit 70 determines, as drive modes of the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51, single drive for driving one of them and stopping the other. That is, when the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 have been twin driven so far, switching to single drive with a high pressure fuel pump different from the high pressure fuel pump previously driven single If it has already been single driven, it continues single driving with the same high pressure fuel pump. Thereafter, the series of switching determination processing by the electronic control unit 70 ends, and the processing of the electronic control unit 70 returns to step S11.

  On the other hand, as described above, when it is determined "NO" in any of steps S11 to S15, the process of the electronic control unit 70 proceeds to step S17. In step S17, the electronic control unit 70 determines, as drive modes of the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51, twin drive for driving both of them. That is, when the first high-pressure fuel pump 31 or the second high-pressure fuel pump 51 is single-driven so far, it switches to twin-drive, and continues twin-drive when it is already twin-driven. Thereafter, the series of switching determination processing by the electronic control unit 70 ends, and the processing of the electronic control unit 70 returns to step S11.

  Next, control processing of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 by the electronic control unit 70 (pump control unit) will be described. The control process of the high pressure fuel pump is repeatedly performed every predetermined control cycle until the operation of the internal combustion engine 10 is ended after the internal combustion engine 10 is started.

  As shown in FIG. 3, when the control process of the fuel pump is started, the process of the electronic control unit 70 shifts to step S21. In step S21, the electronic control unit 70 calculates a proportional term P used for feedback control. The proportional term P multiplies the deviation between the target fuel pressure of the first high pressure delivery pipe 41 and the actual fuel pressure FPH detected by the high pressure fuel pressure sensor 43 (target fuel pressure-actual fuel pressure FPH) by a predetermined proportional term gain. It is determined by The proportional term gain is determined in advance by performing tests and simulations. After the proportional term P is calculated, the proportional term P is determined as the proportional term P used for feedback control. Thereafter, the process of the electronic control unit 70 proceeds to step S22.

  In step S22, the electronic control unit 70 determines whether or not the drive mode of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 is twin drive. When it is determined that the twin drive is performed (YES in step S22), the process of the electronic control unit 70 proceeds to step S23.

  In step S23, the electronic control unit 70 calculates an integral term Itw during twin drive. The integral term Itw at the time of twin drive is an actual fuel pressure detected by the target fuel pressure of the first high pressure delivery pipe 41 and the high pressure side fuel pressure sensor 43 in a state where the first high pressure fuel pump 31 and the second high pressure fuel pump 51 are twin driven. It is obtained by adding a value obtained by multiplying the integral term gain by the deviation from the fuel pressure FPH to the previously calculated integral term Itw during twin drive. Therefore, immediately after the current (current) twin drive is started, that is, when the deviation between the target fuel pressure of the first high pressure delivery pipe 41 and the actual fuel pressure FPH detected by the high pressure side fuel pressure sensor 43 is not calculated yet. The integral term Itw for driving is equal to the integral term Itw for twin driving at the end of the previous twin driving. The integral term gain is determined in advance by performing tests and simulations.

  As described above, the integral term Itw at the time of twin drive is not updated when the first high pressure fuel pump 31 or the second high pressure fuel pump 51 is single driven, and the integral term Itw at the time of twin drive is at the time of single drive. The status is not reflected.

  After the integral term Itw during twin drive is calculated as described above, the process of the electronic control unit 70 proceeds to step S24. In step S24, the integral term Itw during twin drive calculated in step S23 is determined as an integral term I used for feedback control. Thereafter, the process of the electronic control unit 70 proceeds to step S25.

  In step S25, the electronic control unit 70 calculates the feedforward term FFtw in twin drive. The feedforward term FFtw at the time of twin drive is calculated by multiplying the required injection quantity of each first in-cylinder injection valve 42 and each second in-cylinder injection valve 62 by the feedforward term gain. The feed-forward term gain is obtained in advance by performing tests and simulations under the premise that the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 are twin-driven. In step S26 thereafter, the feedforward term FFtw during twin drive calculated in step S25 is determined as the feedforward term FF used for feedforward control. After step S26, the process of the electronic control unit 70 proceeds to step S27.

  In step S27 after step S26, the electronic control unit 70 uses the proportional term P determined in step S21 and the integral term I determined in step S24 to select the first high pressure fuel pump 31 and the second high pressure fuel pump 51. Control feedback. Further, the electronic control unit 70 performs feedforward control of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 using the feedforward term FF determined in step S26. More specifically, the electronic control unit 70 outputs an operation signal MSh1 reflecting the calculated and determined proportional term P, integral term I, and feedforward term FF to the electromagnetic spill valve 36 of the first high pressure fuel pump 31. Similarly, the electronic control unit 70 outputs, to the electromagnetic spill valve 56 of the second high pressure fuel pump 51, an operation signal MSh2 reflecting the calculated and determined proportional term P, integral term I, and feed forward term FF. Thereafter, the control process of the series of fuel pumps by the electronic control unit 70 ends, and the process of the electronic control unit 70 returns to step S21.

  On the other hand, when it is determined in step S22 that twin drive is not performed, that is, single drive is determined (NO in step S22), the process of the electronic control unit 70 proceeds to step S33.

  In step S33, the electronic control unit 70 calculates an integral term Isg during single drive. The integral term Isg during single drive is the value obtained by multiplying the integral term gain by the deviation between the target fuel pressure of the first high pressure delivery pipe 41 and the actual fuel pressure FPH detected by the high pressure side fuel pressure sensor 43 It is obtained by adding to the integral term Isg. Therefore, immediately after the current (current) single drive is started, that is, when the deviation between the target fuel pressure of the first high pressure delivery pipe 41 and the actual fuel pressure FPH detected by the high pressure side fuel pressure sensor 43 is not yet calculated. The integral term Isg at the time of driving is equal to the integral term Isg at the time of single drive at the end of the previous single drive. Note that this integral term gain is the same value as the integral term gain used when calculating the integral term Itw in twin drive.

  After calculating the integral term Isg during single drive as described above, the process of the electronic control unit 70 proceeds to step S34. In step S34, the integral term Isg during single drive calculated in step S33 is determined as an integral term I used for feedback control. Thereafter, the process of the electronic control unit 70 proceeds to step S35.

  In step S35, the electronic control unit 70 calculates the feedforward term FFtw in twin drive. The method of calculating the feedforward term FFtw at the time of twin drive is the same as the method of calculating the feedforward term FFtw at the time of twin drive in step S25 described above. Thereafter, the process of the electronic control unit 70 proceeds to step S36.

  In step S36, the electronic control unit 70 multiplies the feedforward term FFtw calculated in step S35 by the correction gain Kff, and determines the value as the feedforward term FF used in feedforward control. In this embodiment, the correction gain Kff is "2". Also, multiplying the feedforward term FFtw by the correction gain Kff is equivalent to multiplying the feedforward term gain by the correction gain Kff (twice). When the feedforward term FF is determined, the process of the electronic control unit 70 proceeds to step S27.

  In step S27 after step S36, the electronic control unit 70 uses the proportional term P determined in step S21 and the integral term I determined in step S34 to select the first high-pressure fuel pump 31 or the second high-pressure fuel pump 51. Control feedback. Further, the electronic control unit 70 performs feedforward control of the first high pressure fuel pump 31 or the second high pressure fuel pump 51 using the feedforward term FF determined in step S36. When the process proceeds to step S27 after step S36, only one of the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 is driven, ie, single drive. Therefore, the high pressure fuel pump which is being driven among the first high pressure fuel pump 31 and the second high pressure fuel pump 51 is subjected to feedback control and feedforward control, and the high pressure fuel pump which is stopped remains stopped. .

The actions and effects of the above embodiment will be described.
It is assumed that the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 of the internal combustion engine 10 are switched from twin-driven to single-drive. At this time, in the twin drive, the fuel pressure can be raised by two high pressure fuel pumps, but in the single drive, the fuel pressure can be raised only by one high pressure fuel pump. Nevertheless, if the integral term during twin drive is subsequently used also for single drive, the actual fuel pressure FPL does not easily rise to the target fuel pressure immediately after switching to single drive, and until the actual fuel pressure FPH reaches the target fuel pressure. take time.

  Further, it is assumed that the single drive state where either the first high pressure fuel pump 31 or the second high pressure fuel pump 51 of the internal combustion engine 10 is driven is switched to the twin drive state where both are driven. At this time, in single drive, the fuel pressure is increased by one high pressure fuel pump, whereas in twin drive, it is possible to increase fuel pressure by two high pressure fuel pumps. Nevertheless, if the integral term in single drive is subsequently used also in twin drive, the actual fuel pressure FPH rises sharply immediately after switching the twin drive, and the actual fuel pressure FPH exceeds the target fuel pressure and overshoots excessively. There is a risk of

  In this respect, in the above embodiment, the integral term Itw during twin drive is not updated when single drive is performed, and the integral term Itw during twin drive does not reflect the state during single drive. Similarly, the integral term Isg during single drive is not updated when twin drive is performed, and the integral term Isg during single drive does not reflect the state during twin drive. Therefore, at the time of switching between twin drive and single drive, it is possible to suppress that the actual fuel pressure FPH becomes difficult to rise or that the overshoot is generated due to an excessive rise.

  As in the above embodiment, when the integral term Itw in twin drive and the integral term Isg in single drive are handled separately, each integral term is recalculated each time the twin drive and the single drive are switched. It is conceivable. However, in this case, it may not be possible to calculate an appropriate integral term according to the state of the internal combustion engine 10 at that time immediately after switching between twin drive and single drive. Specifically, an integral term used for feedback control can be calculated more appropriately if it is calculated based on the deviation between the actual fuel pressure FPH and the target fuel pressure for a predetermined period or more. Therefore, immediately after switching between twin drive and single drive, an integral term is calculated using an integral term (initial value) determined in advance, or based on an incomplete integrated value for which a predetermined period has not passed. I have no choice but to do it. When the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 are feedback-controlled using such an integral term, the actual fuel pressure FPH changes significantly at the time of switching between twin drive and single drive. It takes a long time to converge to the fuel pressure.

  In the present embodiment, as shown in the flowchart of FIG. 2, switching from twin drive to single drive is performed when a plurality of conditions are satisfied, and single drive is not satisfied even if any one of a plurality of conditions is not satisfied. Switch to twin drive. Therefore, there is a high possibility that the state of the internal combustion engine 10 when switching to the single drive and the state of the internal combustion engine 10 immediately before the end of the single drive are similar. Focusing on this point, in this embodiment, when switching from twin drive to single drive, the integral term at the end of the previous single drive is adopted. Thus, the integral term at the end of the twin drive is adopted immediately after the switching to the single drive, or the situation of the internal combustion engine 10 is reflected more than in the case of using a predetermined integral term immediately after the switching to the single drive. There is a high probability that an appropriate integral term can be calculated.

  By the way, as described above, when the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 are driven in a single manner, the actual fuel pressure FPH tends to be hard to increase as compared with the twin drive. Therefore, for example, the integral term gain used to calculate the proportional term gain and the integral term I used to calculate the proportional term P should be larger in the single drive than in the twin drive. Is considered. However, if the proportional term gain and the integral term gain are simply increased, the actual fuel pressure FPH tends to overshoot and undershoot.

  Further, the actual fuel pressure FPH is lowered by the injection of fuel from each of the first in-cylinder injection valves 42 and each of the second in-cylinder injection valves 62. Then, whether the first high-pressure fuel pump 31 and the second high-pressure fuel pump 51 are single-driven or twin-driven, fuel is supplied from the first in-cylinder injection valves 42 and the second in-cylinder injection valves 62. Is injected. That is, the decrease in the actual fuel pressure FPH is highly dependent on the fuel injection amount from each first in-cylinder injection valve 42 and each second in-cylinder injection valve 62, and is small depending on whether it is twin drive or single drive. On the other hand, as described above, the increase in the actual fuel pressure FPH is highly dependent on whether it is twin drive or single drive. Therefore, as the proportional term gain and the integral term gain are increased in accordance with the fact that the actual fuel pressure FPH does not easily increase in single drive, it is used as a proportional term gain and an integral term gain when the actual fuel pressure FPH decreases. May be too large.

  In the above embodiment, the same value is used for the proportional term gain and the integral term gain both in the case of twin drive and in the case of single drive. Therefore, as described above, the occurrence of excessive overshoot or undershoot in the actual fuel pressure FPH can be suppressed.

  In the above embodiment, the fuel injection amount of the three in-cylinder injection valves may be obtained by one high pressure fuel pump in the twin drive, while the fuel injection of six in-cylinder injection valves in the single drive is performed by the one high pressure fuel pump. I have to pay for it. That is, in single drive, the amount of fuel discharged from one high-pressure fuel pump is doubled. Therefore, in the present embodiment, the feedforward term FF used in single drive is set to be the correction gain Kff (twice) of the feedforward term FFtw in twin drive. In other words, in single drive, the feed-forward term gain is set to (twice) the correction gain Kff in twin drive. Therefore, it is possible to suppress the responsiveness of the actual fuel pressure FPH from being deteriorated during single drive. As a result, in single drive, the time until the actual fuel pressure FPH converges to the target fuel pressure can be shortened.

  In the internal combustion engine 10, an accurate amount of fuel is injected from the first in-cylinder injection valve 42 and the second in-cylinder injection valve 62. In addition, even if the actual injection amount from the first in-cylinder injection valve 42 or the second in-cylinder injection valve 62 deviates from the required injection amount, the deviation amount is equal to the first high pressure delivery pipe 41 or the second high pressure delivery. Compared to the volume of the pipe 61, it is very small. Therefore, even if the feedforward term gain is increased during single drive, it is unlikely that an excessive overshoot or undershoot will occur in the actual fuel pressure FPH.

The above embodiment can be modified as follows. In addition, it is also possible to apply a combination of a plurality of the following modifications as necessary.
In the above embodiment, the technology related to switching between twin drive and single drive is applied to the V-type six-cylinder internal combustion engine 10, but is applied to the internal combustion engine 10 with another V-type cylinder, such as V-type eight cylinders. It is also good. Furthermore, if two high-pressure fuel pumps are provided, the technology relating to the switching between the twin drive and the single drive of the above embodiment can be applied even without the V-type internal combustion engine 10.

  The first port injection valve 22, the second port injection valve 26, and their related configurations may be omitted. That is, as the fuel injection valve of the internal combustion engine 10, the first in-cylinder injection valve 42 and the second in-cylinder injection valve 62 may be provided.

  -If two feed pumps 12 are provided as fuel pumps for supplying fuel to the first low pressure delivery pipe 21 and the second low pressure delivery pipe 25, these two feed pumps 12 can be driven by the twin drive of the above embodiment and The technology related to single drive switching can also be applied.

  In the above embodiment, the high pressure side fuel pressure sensor 43 is provided on the first high pressure delivery pipe 41, but the high pressure side fuel pressure sensor 43 may be provided on the second high pressure delivery pipe 61 or the connection passage 66. By the way, since the first high pressure delivery pipe 41 and the second high pressure delivery pipe 61 are connected by the connection passage 66, the fuel pressure in the inside becomes the same fuel pressure. However, depending on the arrangement and shape of the first high pressure delivery pipe 41 and the second high pressure delivery pipe 61, for example, it takes time for the change in fuel pressure in the first high pressure delivery pipe 41 to propagate to the second high pressure delivery pipe 61 It may be. Therefore, for example, fuel pressure sensors may be provided for both the first high pressure delivery pipe 41 and the second high pressure delivery pipe 61, and the average value of the fuel pressure detected by these fuel pressure sensors may be used as the actual fuel pressure FPH.

  In the above embodiment, the return pipe 64 extending from the second high pressure delivery pipe 61 to the fuel tank 11 is provided. However, the mode of returning the fuel to the fuel tank 11 is not limited to this. A so-called returnless piping structure may be employed.

When the first high-pressure fuel pump 31 or the second high-pressure fuel pump 51 is stopped, the electromagnetic spill valves 36 and 56 may be controlled to be open.
The conditions for switching to single drive are not limited to those exemplified in the above embodiment (steps S11 to S15 in FIG. 2) in the determination process of switching between twin drive and single drive. Any of the conditions exemplified in the above embodiment may be omitted, or other conditions may be added. For example, an exhaust gas purification catalyst may be provided in the exhaust passage of the internal combustion engine 10. Then, the required injection amount of the first in-cylinder injection valve 42 or the second in-cylinder injection valve 62 may be increased in order to raise the temperature of the exhaust and warm up the exhaust purification catalyst. That such warm-up processing of the exhaust purification catalyst is not performed may be set as one of the conditions for switching to the single drive.

The high pressure fuel pump that is stopped at the time of single drive may be fixed to either the first high pressure fuel pump 31 or the second high pressure fuel pump 51.
For the feedback control of the first high pressure fuel pump 31 and the second high pressure fuel pump 51, a derivative term may be used in addition to the use of the proportional term P and the integral term I. That is, the first high pressure fuel pump 31 and the second high pressure fuel pump 51 may be subjected to PID control.

  The proportional term gain and the integral term gain may not necessarily have the same value in the twin drive mode and the single drive mode. If excessive overshoot or undershoot does not occur, for example, the proportional term gain and the integral term gain in single drive may be set larger than those in twin drive.

  The calculation method of the integral term Itw for twin drive and the integral term Isg for single drive is not limited to the example of the above embodiment. For example, it may be obtained by integrating a deviation between the target fuel pressure of the first high pressure delivery pipe 41 and the actual fuel pressure FPH detected by the high pressure side fuel pressure sensor 43 for a predetermined period, and multiplying the integrated value by the integral term gain. In this case, for example, immediately after switching from twin drive to single drive, integration may be performed retroactively to the deviation immediately before the end of the previous single drive instead of the deviation during twin drive.

  The correction gain Kff used when calculating the feedforward term FF is not limited to “2”. If a value larger than “1” is used as the correction gain Kff, it is possible to compensate for the poor responsiveness of the actual fuel pressure FPH during single drive by the correction gain Kff. As described above, in single drive, the number of in-cylinder injection valves that must be supplied with fuel by one high-pressure fuel pump is doubled in twin drive. Therefore, the correction gain Kff has a limit of "2", and if it is larger than that, overshoot or undershoot of the actual fuel pressure FPH may easily occur.

The correction based on the correction gain Kff may be omitted, and the same feedforward term gain may be used in twin drive and single drive.
In the embodiment described above, the feedforward term FF is calculated by multiplying the feedforward term FFtw during twin drive by the correction gain Kff during single drive, but the invention is not limited to this. For example, in twin drive, the feedforward term FF may be calculated by dividing the correction gain Kff by the feedforward term in single drive. Also, for example, feed forward term gains may be prepared separately for twin drive and single drive.

  Upper limits may be set for the proportional term P, the integral term I, and the feedforward term FF. By setting the upper limit value to these, it can be suppressed that the first high pressure fuel pump 31 and the second high pressure fuel pump 51 are operated with an excessively large load.

  In the case of setting upper limit values of the proportional term P, the integral term I, and the feed forward term FF, the upper limit value may be set as a deviation from the value calculated previously. In this case, sudden changes in the load of the first high pressure fuel pump 31 and the second high pressure fuel pump 51 can be suppressed.

  The feedforward control using the feedforward term FF may be omitted. Even if the feedforward control is omitted, the actual fuel pressure FPH converges to the target fuel pressure by feedback control using the proportional term P and the integral term I.

  Reference Signs List 10 internal combustion engine 11 fuel tank 12 feed pump 13 filter 15 low pressure fuel piping 16 first low pressure fuel piping 16a first branch pipe 16b second branch pipe 17 17th 2 low pressure fuel piping, 17a: first branch pipe, 17b: second branch pipe, 21: first low pressure delivery pipe, 22: first port injection valve, 23: low pressure fuel pressure sensor, 25: second low pressure delivery pipe, 26: second port injection valve, 31: first high pressure fuel pump, 32: cylinder, 33: plunger, 34: cam follower, 35: cam, 36: electromagnetic spill valve, 37: first high pressure fuel pipe, 38: check valve 41: first high pressure delivery pipe 42: first in-cylinder injection valve 43: high pressure fuel pressure sensor 51: second high pressure fuel pump 52: cylinder 53: plunger 54: cam follower 55 Cam, 56: electromagnetic spill valve, 57: first high pressure fuel pipe, 58: check valve, 61: second high pressure delivery pipe, 62: second in-cylinder injection valve, 63: return valve, 64: return pipe, 66: Connection passage 70 Electronic control unit 71 Central processing unit 72 ROM 73 RAM 81 Acceleration sensor 82 Speed sensor 83 Throttle sensor FPL Actual fuel pressure of first low pressure delivery pipe FPH ... Actual fuel pressure of the first high pressure delivery pipe, Acc ... Stepped amount of accelerator pedal, SP ... Vehicle speed, TA ... Throttle opening, MSp ... Operation signal of the first port injection valve and second port injection valve, MSd ... First cylinder Operation signal of the inner injection valve and the second in-cylinder injection valve, MSf ... operation signal of the feed pump, MSh 1 ... operation signal of the first high pressure fuel pump, MSh 2 ... second pressure Operation signal of the charge pump.

Claims (3)

A first fuel pump for pressurizing and discharging fuel; a first fuel passage through which the fuel discharged by the first fuel pump flows; and a first fuel injection valve for injecting the fuel supplied from the first fuel passage ,
A second fuel pump for pressurizing and discharging the fuel; a second fuel passage through which the fuel discharged by the second fuel pump flows; and a second fuel injection valve for injecting the fuel supplied from the second fuel passage A connection passage connecting the first fuel passage and the second fuel passage; and a fuel pressure sensor detecting a fuel pressure of any one of the first fuel passage, the second fuel passage, and the connection passage. A fuel pump control device applied to an internal combustion engine, comprising:
Twin drive for driving both the first fuel pump and the second fuel pump according to the operating condition of the internal combustion engine, or single drive for driving any one of the first fuel pump and the second fuel pump And a pump switching unit for switching
Feedback control of the first fuel pump and the second fuel pump using the proportional term and the integral term for twin drive so that the actual fuel pressure detected by the fuel pressure sensor approaches the target fuel pressure when the twin drive is performed. The first fuel pump or the second fuel pump using the proportional term and the integral term for single drive so that the actual fuel pressure detected by the fuel pressure sensor approaches the target fuel pressure when the single drive is performed. And a pump control unit for feedback control,
The pump control unit
When twin drive is performed, the integral term for single drive is not updated, and when twin drive is switched to single drive, feedback control is performed using the integral term for single drive at the end of the previous single drive,
When single drive is used, feedback control is performed using the integral term for twin drive at the end of the previous twin drive when switching from single drive to twin drive without updating the integral term for twin drive. A fuel pump control device characterized by The pump control unit
Calculate a proportional term using a proportional term gain common to the twin drive and the single drive,
The fuel pump control device according to claim 1, wherein an integral term for single drive and an integral term for twin drive are calculated using an integral term gain common to the twin drive and the single drive. The pump control unit uses the feedforward term based on the required injection amount of the first fuel injection valve and the second fuel injection valve, in addition to the feedback control, to use the first fuel pump and the second fuel pump. Feed forward control,
The pump control unit sets the feedforward term gain in the single drive to a value larger than 1 and not more than 2 times the feedforward term gain in the twin drive. The fuel pump control device according to 2.