Control device for a vehicle

Abstract

A vehicle control device addresses the issue of suppressing reduced engine startability. The vehicle includes: an engine serving as a driving power source; a motor drive mechanism capable of driving the engine; and a pump discharging fuel into the engine. The vehicle control device includes: a start control unit that, while continuously cutting off fuel to the engine, maintains the engine speed at a level higher than the complete combustion speed required for complete combustion via the motor drive mechanism, and performs high-speed start control to initiate fuel injection to start the engine; and a feedback control unit that, through feedback control, updates the proportional term while controlling the pump's discharge flow rate based on a proportional term and an integral term of the deviation obtained from a target fuel pressure (a target value of fuel pressure supplied to the engine by the pump) between the target fuel pressure and the actual fuel pressure.

Description

Technical Field

[0001] This invention relates to a vehicle control device. Background Technology

[0002] The discharge flow rate of the pump that discharges fuel to the engine is controlled by feedback control based on the proportional and integral terms of the deviation obtained from the target fuel pressure, which is a target value of fuel pressure supplied to the engine, minus the actual fuel pressure (for example, see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-002309 Summary of the Invention

[0004] When the engine starts, it is driven by the motor to begin fuel injection. However, the fuel pressure supplied to the engine from the pump may be insufficient at startup. Therefore, for example, it may be considered to fix the integral term at a lower limit until a predetermined time when the engine's combustion state stabilizes. This avoids further deterioration of the integral term and ensures fuel injection while the actual fuel pressure remains high relative to the target fuel pressure, thus eliminating the insufficient fuel pressure at engine startup. In this case, the integral term is updated after the predetermined time has elapsed.

[0005] Here, sometimes fuel injection is initiated to start the engine after a fuel cutoff period that has lasted for the aforementioned specified time. In this case, since no fuel has been injected after the specified time but before fuel injection begins, the actual fuel pressure does not drop to the target fuel pressure to update the integral term. Therefore, the pump's discharge flow rate is considered excessive, the integral term decreases, and the pump's discharge flow rate also decreases. Consequently, insufficient fuel pressure at the start of subsequent fuel injection may lead to reduced engine startability.

[0006] Therefore, the object of the present invention is to provide a vehicle control device that suppresses the reduction in engine startability.

[0007] The aforementioned objective can be achieved by a control device for a vehicle comprising: an engine serving as a power source for driving; a motor drive mechanism capable of driving the engine; and a pump discharging fuel into the engine. The control device comprises: a start-up control unit that, while continuously cutting off fuel to the engine, maintains the engine speed at a position higher than the full combustion speed required for complete combustion via the motor drive mechanism, and performs high-speed start-up control to initiate fuel injection to start the engine; and a feedback control unit that, through feedback control based on a proportional term and an integral term of the deviation obtained from a target fuel pressure (a target value of fuel pressure supplied to the engine by the pump) minus the actual fuel pressure, updates the proportional term while controlling the pump's discharge flow rate. During the fuel cut-off period before the start of fuel injection by the start-up control unit, the feedback control unit fixes the integral term at a lower limit value, and updates the integral term after the start of fuel injection by the start-up control unit.

[0008] The feedback control unit fixes the integral term at the lower limit value during the execution of fuel cut-off before the engine speed reaches the full combustion speed, i.e., the full combustion speed elapsed time is less than the specified update stop time or during the execution of the full combustion speed elapsed time before the start of the engine fuel injection by the start control unit. After the full combustion speed elapsed time is longer than the update stop time and the engine fuel injection by the start control unit begins, the integral term is updated. In the high-speed start control, the update stop time is shorter than the time from the engine speed reaching the full combustion speed until the start of the engine fuel injection. The start control unit can selectively execute the high-speed start control and start the low-speed start control of the engine by starting the engine fuel injection from the start of the engine motor drive until the engine speed reaches the full combustion speed.

[0009] In the high-speed start control, the start control unit can maintain the engine speed at an idle speed higher than the full detonation speed by using a motor driven by the motor drive mechanism.

[0010] The feedback control unit can fix the integral term to the value before the fuel cut-off after the engine starts and during the execution of the fuel cut-off.

[0011] The motor drive mechanism is a motor that serves as a driving power source, and the pump can be a low-pressure pump that dispenses fuel to the intake manifold injection valve of the engine.

[0012] Invention Effects

[0013] It can provide a vehicle control device that suppresses the reduction in engine startability. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a hybrid vehicle.

[0015] Figure 2 This is a schematic diagram of the engine's structure.

[0016] Figure 3 A and Figure 3 B is a timing diagram illustrating the integral term update control during engine startup in the comparative example.

[0017] Figure 4 This is a timing diagram illustrating the integral term update control during engine 10 startup in this embodiment.

[0018] Figure 5 This is a flowchart illustrating the integral term update control of this embodiment. Detailed Implementation

[0019] [Brief Structure of Hybrid Vehicles]

[0020] Figure 1 This is a schematic structural diagram of a hybrid vehicle 1. The hybrid vehicle 1 includes: an engine 10; a first motor 61; a second motor 62; a power distribution mechanism 63; a transmission mechanism 64; drive wheels 70; a PCU 80; a battery 90; and an Electronic Control Unit (ECU) 100. The engine 10, the first motor 61, and the second motor 62 are equipped as the driving source for the hybrid vehicle 1.

[0021] The first motor 61 and the second motor 62 are connected to the battery 90 via the PCU 80. The first motor 61 and the second motor 62 function as motors that generate driving force for the vehicle based on power supplied from the battery 90. Furthermore, the first motor 61 and the second motor 62 also function as generators that produce electricity by generating regenerative power to charge the battery 90 based on power transmitted from the engine 10 or the drive wheels 70. The power supplied between the first motor 61 and the second motor 62 and the battery 90 is regulated by the PCU 80. The PCU 80 is controlled by the ECU 100. The PCU 80 converts DC voltage from the battery 90 to AC voltage, or converts AC voltage from the first motor 61 or the second motor 62 to DC voltage.

[0022] The power distribution mechanism 63 mechanically connects the crankshaft of the engine 10, the rotating shaft of the first motor 61, and the output shaft of the power distribution mechanism 63. The power distribution mechanism 63 is, for example, a planetary gear mechanism including a sangia, a planetary carrier, a pinion gear, and a ring gear. The output shaft of the power distribution mechanism 63 is connected to the transmission mechanism 64. Furthermore, the rotating shaft of the second motor 62 is also connected to the transmission mechanism 64. Through the transmission mechanism 64, the driving force of the engine 10 or each of the first motor 61 and the second motor 62 is transmitted to the drive wheel 70. Additionally, the first motor 61 performs motor drive to force the engine 10 to rotate when the engine 10 is started. The first motor 61 is an example of a motor drive mechanism.

[0023] ECU100 is an electronic control unit that includes arithmetic processing circuits for various calculations involved in vehicle driving control and a memory storing control programs or data. ECU100 is an example of a vehicle control device, and more specifically, it functionally implements the start-up control unit and feedback control unit described later.

[0024] As will be explained in detail later, the ECU 100 selectively executes high-speed start control and low-speed start control for starting the engine 10. High-speed start control is the control that starts fuel injection to start the engine 10 when the engine speed is maintained above the full combustion speed by the motor drive based on the first motor 61. Low-speed start control is the control that starts fuel injection to start the engine 10 from the start of motor drive of the engine 10 until the engine speed reaches the full combustion speed. The full combustion speed is the engine speed at which the engine 10 achieves full combustion and becomes capable of independent operation. The above control is an example of the control executed by the start control unit.

[0025] For example, ECU 100 can perform high-speed start control when the battery 90's charge level is above a threshold, and perform low-speed start control when the battery 90's charge level is below the threshold. Thus, when the battery 90's charge level is above the threshold, the amount of fuel consumed when starting the engine 10 is suppressed; when the battery 90's charge level is below the threshold, the amount of electricity consumed by the battery 90 when starting the engine 10 is suppressed.

[0026] In ECU 100, vehicle speed sensor 101, crankshaft angle sensor 102, and coolant temperature sensor 103 are electrically connected. Vehicle speed sensor 101 detects the driving speed of hybrid vehicle 1. Crankshaft angle sensor 102 detects the engine speed. Coolant temperature sensor 103 detects the temperature of the coolant cooling engine 10.

[0027] [Engine's general structure]

[0028] Figure 2This is a schematic diagram of the engine 10. The engine 10 includes a fuel tank 21, a low-pressure pump 22, a low-pressure pipe 25, a low-pressure distribution pipe 26, a high-pressure delivery pipe 36, fuel pressure sensors 28 and 38, and a high-pressure pump 40.

[0029] Engine 10 is a spark-ignition four-cylinder gasoline engine equipped with in-cylinder injection valves 37 for injecting fuel into each cylinder and intake manifold injection valves 27 for injecting fuel into each intake manifold. Furthermore, engine 10 is equipped with a camshaft 15 that drives intake or exhaust valves in conjunction with the crankshaft.

[0030] Fuel tank 21 stores fuel. Low-pressure pump 22 pressurizes the fuel in fuel tank 21 and discharges it into low-pressure pipe 25. A portion of the fuel discharged into low-pressure pipe 25 is supplied to intake manifold injection valve 27 via low-pressure distribution pipe 26. Thus, low-pressure pump 22 discharges fuel to engine 10. The remaining portion of the fuel discharged into low-pressure pipe 25 is also supplied to high-pressure pump 40 via high-pressure pipe 25a, which branches off from low-pressure pipe 25. High-pressure pump 40 pressurizes the fuel supplied from branch pipe 25a and discharges it into high-pressure distribution pipe 36. The fuel pressurized by high-pressure pump 40 is supplied to cylinder injection valve 37 via high-pressure distribution pipe 36.

[0031] Fuel pressure sensors 28 and 38 detect the fuel pressure in the low-pressure distribution pipe 26 and the high-pressure distribution pipe 36, respectively. The ECU100 acquires the detection values ​​of fuel pressure sensors 28 and 38.

[0032] The ECU 100 adjusts the port injection rate and cylinder injection rate based on the operating region of the engine 10. The port injection rate is the ratio of the total fuel injection quantity from the port injection valve 27 and the cylinder injection valve 37 to the fuel injection quantity from the port injection valve 27. The cylinder injection rate is the ratio of the fuel injection quantity from the cylinder injection valve 37 to the total fuel injection quantity. For example, when the engine 10 operates in a low-load region, the port injection rate is 100%, and the cylinder injection rate is 0%. When the engine 10 operates in a high-load region, the port injection rate is 0%, and the cylinder injection rate is 100%. When the engine 10 operates in a medium-load region, the port injection rate and cylinder injection rate are, for example, 50% each. Furthermore, the port injection rate and cylinder injection rate are controlled so that the sum of the port injection rate and cylinder injection rate is always 100%.

[0033] The high-pressure pump 40 includes a cylinder 41, a plunger 42, a pressurization chamber 43, an intake passage 45, an exhaust passage 47, a pressure relief passage 49, an intake valve 50, an exhaust valve 47a, and a pressure relief valve 49a. The plunger 42 moves up and down within the cylinder 41 by the rotation of a cam CP that rotates together with the camshaft 15. The volume of the pressurization chamber 43 increases or decreases by the movement of the plunger 42. The pressurization chamber 43 is defined by the cylinder 41 and the plunger 42.

[0034] The intake passage 45 connects to the high-pressure pipe 25a, which branches off from the low-pressure pipe 25, and to the pressurization chamber 43. A pulsation damper 44 is provided in the intake passage 45 to suppress fuel pressure pulsations. The pressure relief passage 49 connects the pressurization chamber 43 and the high-pressure distribution pipe 36. The discharge passage 47 bypasses the pressure relief valve 49a and connects to the pressure relief passage 49. The discharge valve 47a allows fuel flow in the discharge passage 47 from the pressurization chamber 43 side to the high-pressure delivery pipe 36 side, but restricts flow in the opposite direction. The pressure relief valve 49a allows fuel flow in the pressure relief passage 49 from the high-pressure delivery pipe 36 side to the pressurization chamber 43 side, but restricts flow in the opposite direction.

[0035] The intake valve 50 is a solenoid valve controlled by the ECU 100. When the intake valve 50 opens, the plunger 42 descends, and fuel is filled from the high-pressure pipe 25a into the pressurization chamber 43 via the intake passage 45. Then, the intake valve 50 closes, the plunger 42 rises, and the fuel in the pressurization chamber 43 is pressurized. Next, when the force exerted by the fuel pressure from the pressurization chamber 43 side on the discharge valve 47a exceeds a predetermined pressure, the discharge valve 47a opens, and the pressurized fuel is supplied to the high-pressure delivery pipe 36. The pressure relief valve 49a opens if the fuel pressure in the high-pressure delivery pipe 36 rises excessively.

[0036] [Control of low-pressure pump discharge flow rate]

[0037] The control of the discharge flow rate of the low-pressure pump 22 based on ECU100 is explained. The target discharge flow rate T of the low-pressure pump 22 is calculated based on the following formula.

[0038] Target output flow T = FF term + FB term + corrected flow C

[0039] The FF (feedforward) term is set to increase as the required torque of the engine 10 increases. The FB (feedback) term is calculated based on the deviation obtained by subtracting the actual fuel pressure supplied to the intake manifold injection valve 27 from the target fuel pressure, which is the target value of the fuel pressure supplied to the intake manifold injection valve 27. The FB term is calculated repeatedly over a specified time, such as several msec. The actual fuel pressure is obtained based on the fuel pressure sensor 28. The target fuel pressure is calculated based on the operating state of the engine 10. The correction flow rate C is a correction flow rate that takes into account the operating characteristics of the low-pressure pump 22, etc. The ECU 100 controls the rotational speed of the low-pressure pump 22 so that the discharge flow rate of the low-pressure pump 22 becomes the target discharge flow rate T.

[0040] FB items are calculated based on the following formula.

[0041] FB item = Previous FB item + Proportion item + Integral item

[0042] The previous FB term is the previous value of the FB term. The proportional term is the value obtained by multiplying the above deviation by a specified proportional gain. The integral term is the value obtained by integrating the above deviation over time by a specified integral gain. That is, the low-pressure pump 22 is controlled by feedback through a proportional-integral controller (PI controller).

[0043] [Control of Integral Term Update in Comparative Examples]

[0044] Before explaining the update control of the integral term in this embodiment, the update control of the integral term in the comparative example will be explained. Figure 3 A and Figure 3 B is a timing diagram illustrating the integral term update control during engine 10 startup in the comparative example. Figure 3 A and Figure 3 In section B, the engine speed, the time elapsed until full combustion speed, the fuel injection state, the integral term update state, the integral term, and the shifts in the actual and target fuel pressures supplied to the intake manifold injection valve 27 are shown. The time elapsed until full combustion speed refers to the time elapsed after the engine speed reaches or exceeds the full combustion speed. Furthermore, in both the comparative example and this embodiment, if the integral term is updated, the proportional term is also updated; if the integral term is not updated, the proportional term is also updated. Therefore, there is no case where only the integral term is updated without updating the proportional term. This updating of the proportional or integral term is an example of the processing performed by the feedback control unit.

[0045] Figure 3 Example A illustrates the update control of the integral term in a comparative example when low-speed start-up control is implemented, where fuel injection begins before the engine speed reaches or exceeds the full detonation speed. For example... Figure 3 As shown in Figure A, the engine speed of the engine 10, driven by the first motor 61, increases. A target fuel pressure, which serves as the fuel pressure supplied to the intake manifold injection valve 27, is calculated, and fuel injection of the engine 10 begins (time t1). Here, the integral term is fixed at a lower limit of a positive value. Then, the engine speed increases until it reaches or exceeds the full combustion speed (time t2). If the time elapsed after the full combustion speed exceeds a predetermined update stop time, updating the integral term begins (time t3). The update stop time is set to the time from when the engine speed reaches the full combustion speed until the combustion state of the engine 10 stabilizes and the engine speed stabilizes, during low-speed start-up control. Thus, during the period when the integral term is fixed at the lower limit (times t1 to t3), only the proportional term is updated. During this period, the integral term will not fall below the lower limit, therefore the actual fuel pressure is maintained at a value higher than the target fuel pressure, thereby ensuring the fuel pressure at engine 10 startup.

[0046] If the integral term update begins (at time t3), that is, if feedback control of the low-pressure pump 22 based on the updated proportional and integral terms begins, the actual fuel pressure converges to the target fuel pressure. Then, if fuel cutoff is performed, the integral term remains at the value before fuel cutoff (at time t4x). That is, no update of the integral term is performed.

[0047] As described above, in the comparative example, when the time elapsed for full combustion speed is less than the predetermined update stop time, the integral term is fixed at the lower limit (time t1 to time t3), thereby ensuring the fuel pressure when the engine 10 starts. Furthermore, since the update of the integral term begins after the time elapsed for full combustion speed becomes greater than or equal to the update stop time, the actual fuel pressure converges to the target fuel pressure corresponding to the operating state of the engine 10.

[0048] Figure 3 Example B illustrates an update control of the integral term in a comparative example of high-speed start-up control that initiates fuel injection while maintaining the engine speed above the full detonation speed. Fuel is continuously cut off from time t1 to time t4y, and fuel injection begins at time t4y. Thus, in high-speed start-up control, fuel injection begins while the engine speed is maintained above the full detonation speed by motor drive based on the first motor 61. Specifically, fuel injection begins while maintaining the engine speed at idle speed. Idle speed refers to the speed at which the engine 10 is idling. This suppresses the amount of fuel consumption required to start the engine 10.

[0049] In the comparative example, the integral term is updated during the period from time t3 to time t4y, before fuel injection begins. Therefore, the actual fuel pressure does not decrease to the target fuel pressure, and the integral term is updated under these conditions. In this case, the discharge flow rate of the low-pressure pump 22 is considered excessive, the integral term decreases, and the discharge flow rate of the low-pressure pump 22 also decreases. As a result, when fuel injection begins, the integral term decreases, and the actual fuel pressure may be insufficient.

[0050] [Integral term update control in this embodiment]

[0051] Figure 4 This is a timing diagram illustrating the integral term update control during engine 10 startup in this embodiment. Figure 4 Examples of the same Figure 3 B similarly performs the integral term update control as in this embodiment during high-speed start-up control. Figure 4 The times t1 to t3 shown are Figure 3 A and Figure 3 The times t1 to t3 shown in B correspond to the times indicated. Figure 4The display shows engine speed, time elapsed until full combustion, fuel injection status, time elapsed after occurrence, large deviation indicator, integral term update status, update time, integral term, and the shift in actual and target fuel pressure supplied to the intake manifold injection valve 27. Time elapsed after occurrence refers to the elapsed time after a change in actual fuel pressure occurs due to a change in at least one of the actual and target fuel pressures. The large deviation indicator is activated when the deviation between the actual and target fuel pressures may widen. The update time refers to the cumulative value of the time taken for the integral term to be updated.

[0052] In this embodiment, even if the time elapsed since the full combustion speed exceeds the update stop time, the integral term is not updated (time t3). Then, if fuel injection begins, the integral term is updated (time t4). Therefore, in this embodiment, the integral term is not updated between times t1 and t4. Then, if fuel cutoff is performed, the integral term is not updated and remains fixed at the value of the integral term before fuel cutoff (time t5). Then, if fuel injection begins, the integral term is updated again (time t6). Furthermore, as will be explained in detail later, time t7 represents the moment when the update time becomes the upper limit time. In addition, the update stop time is set to be shorter than the time from when the engine speed reaches the full combustion speed to when fuel injection of engine 10 begins in high-speed start control.

[0053] As described above, in this embodiment, even if the complete combustion speed has elapsed beyond the update stop time, the integral term is not updated (time t3 to time t4) while fuel cutoff continues, and is updated (time t4 to time t5) after fuel injection begins. Therefore, as Figure 3 As shown in B, even without fuel injection, the integral term decreases, thus preventing insufficient fuel pressure when starting the engine 10. This suppresses the reduction in the startability of the engine 10.

[0054] Figure 5 This is a flowchart illustrating the integral term update control of this embodiment. This control is repeatedly executed. The ECU 100 determines whether it is in fuel cutoff and whether the target value of the fuel pressure supplied to the intake manifold injection valve 27, i.e., the target fuel pressure, is constant and the required torque of the engine 10 is constant (step S1). Therefore, if it is in fuel cutoff and the target fuel pressure or required torque is constant, it is determined to be "yes" in step S1. In other cases, such as during fuel injection, it is determined to be "no" in step S1.

[0055] If "Yes" is selected in step S1, ECU100 sets the elapsed time after the event to 0 (step S2) and activates the large deviation flag (step S3). If "No" is selected in step S1, ECU100 counts the elapsed time after the event (step S4).

[0056] After executing step S3 or S4, ECU100 determines whether the elapsed time after the event is greater than or equal to the stabilization time, or whether the update time is less than or equal to the upper limit time (step S5). The stabilization time is the time required from the occurrence of a change in actual fuel pressure until the actual fuel pressure converges to the target fuel pressure. The upper limit time is the upper limit of the cumulative time for the update integral term. Furthermore, the upper limit time is set to be shorter than the stabilization time. If the elapsed time after the event is greater than or equal to the stabilization time, the determination in step S5 is "yes," regardless of the update time. If the update time is less than or equal to the upper limit time, the determination in step S5 is "yes," regardless of the elapsed time after the event. If the elapsed time after the event is less than the stabilization time and the update time is longer than the upper limit time, the determination in step S5 is "no."

[0057] If "yes" is selected in step S5, ECU100 closes the large deviation flag (step S6).

[0058] After executing step S6, or if the result in step S5 is "No", the ECU 100 determines whether the elapsed time of the full-combustion speed is below the update stop time (step S7). The update stop time is set to a time shorter than the aforementioned stabilization time and longer than the upper limit time. If the result in step S7 is "Yes", the ECU 100 sets the update time to 0 (step S8) and fixes the integral term at the lower limit value (step S9). That is, the update of the integral term is stopped. In addition, from the start of motor drive until the engine speed reaches the full-combustion speed, the elapsed time of the full-combustion speed is 0, therefore the result in step S7 is "No" and steps S8 and S9 are executed. Step S9 is an example of the processing performed by the feedback control unit.

[0059] If "No" is received in step S7, ECU100 determines whether the large deviation indicator is off and whether fuel injection is in progress (step S10). If the large deviation indicator is on, "No" is received in step S10 regardless of the fuel injection status. If fuel cut-off is being performed, "No" is received in step S10 regardless of the large deviation indicator. "No fuel injection" indicates that fuel injection is stopped.

[0060] If "Yes" is selected in step S10, the ECU100 counts the update time (step S11) and updates the integral term (step S12). Step S12 is an example of the processing performed by the feedback control unit.

[0061] If the result in step S10 is "No", the ECU100 maintains the update time (step S13) and fixes the integral term to the previous value (step S14). That is, the update of the integral term is stopped. Therefore, if the update time count reaches this point, the update time remains the last counted time; if the update time is 0, the update time remains 0. Furthermore, after the integral term is fixed at the lower limit value (step S9), if the result in steps S7 and S10 is "No", the integral term is fixed to the previous value, i.e., the lower limit value. After the integral term is updated (step S12), if the result in steps S7 and S10 is "No", the value of the integral term in the update before the result in steps S7 and S10 is "No" is fixed to the previous value.

[0062] For example, in Figure 4 In the timing diagram shown, at times t1 to t3, if the condition is "yes" in steps S1, S5, and S7, then steps S2, S3, S6, S8, and S9 are executed sequentially. Here, the large deviation flag is enabled in step S3, but is ultimately disabled in step S6.

[0063] During time intervals t3 and t4, the determination is "yes" in steps S1 and S5, and "no" in steps S7 and S10, and steps S2, S3, S6, S13, and S14 are executed sequentially. Therefore, during time intervals t1 and t3, the integral term is fixed at the lower limit (step S9), and during time intervals t3 and t4, the integral term is fixed at the previous value, i.e., the lower limit (step S14). Step S14 is an example of the processing performed by the feedback control unit.

[0064] During times t4 to t5, the condition is determined as "No" in step S1, and as "Yes" in steps S5 and S10, and steps S4, S6, S11, and S12 are executed sequentially. Times t5 to t6 are the same as times t3 to t4. Times t6 to t7 are the same as times t4 to t5.

[0065] Additionally, at time t7, the decision in step S1 is "No," and step S4 is executed. However, in step S5, the update time is longer than the upper limit time. Therefore, the decision in step S5 differs depending on whether the elapsed time after the event is greater than the stable time. If the elapsed time after the event is less than the stable time, the decision in step S5 is "No," the decision in step S7 is "No," and the decision in step S10 is "Yes," and steps S11 and S12 are executed. Here, step S6 is executed before time t7, so the large deviation flag is also turned off at time t7. If the elapsed time after the event is greater than the stable time, the decision in step S5 is "Yes," the decision in step S7 is "No," and the decision in step S10 is "Yes," and steps S6, S11, and S12 are executed. At time t7, since fuel has been injected, steps S11 and S12 are executed regardless of the decision result in step S5.

[0066] If the determination in step S1 is "yes" after time t7, for example, if fuel cutoff is performed, step S3 is executed. If the determination in step S5 is "no", step S10 is determined to be "no" and steps S13 and S14 are executed. If the determination in step S5 is "yes", step S6 is executed, but in this case, step S10 is determined to be "no" and steps S13 and S14 are executed.

[0067] Here, for example, by extending the update stop time to Figure 3 B's time t4y or Figure 4 At time t4, insufficient fuel pressure during engine 10 startup in high-speed start control can be avoided. However, if the update stop time is extended in this way, in low-speed start control, update will stop even after the combustion state of engine 10 has stabilized. As a result, in low-speed start control, it takes time for the actual fuel pressure to converge to the target fuel pressure, and the control of the actual fuel pressure may be reduced. Therefore, as described above, after the time elapsed from the full combustion speed becomes the update stop time, if fuel injection is in progress, the integral term is updated (step S12); if fuel cutoff is in progress, the integral term is fixed at the previous value, i.e., the lower limit value, and update continues to stop (step S14). Thus, even if either low-speed start control or high-speed start control is implemented, the startability of engine 10 and the controllability of fuel pressure can be balanced.

[0068] As mentioned above, ECU100 can also be based on Figure 5 The flowchart corresponds to Figure 3 Integral update control in the low-speed start-up control shown in Figure A. Figure 3During time t3 to t4x of step A, since fuel has already been injected, at time t3, the result is determined as "No" in step S1, "Yes" in step S5, and "No" in step S7, and step S12 is executed. Furthermore, between time t3 and t4x, the update time in step S5 is longer than the upper limit time, resulting in a "No" result. However, the large deviation flag is turned off before the "No" result in step S5, so the result is determined as "Yes" in step S10, and step S12 is executed.

[0069] In this embodiment, both high-speed start control and low-speed start control are implemented by motor drive based on the first motor 61, but this is not a limitation. For example, when a starter motor for starting the engine 10 is provided, motor drive can be performed by the first motor 61 in high-speed start control, and by the starter motor in low-speed start control. In this case, the first motor 61 and the starter motor are equivalent to motor drive mechanisms. Furthermore, if the output of the starter motor is high enough to perform high-speed start control, both high-speed start control and low-speed start control can be achieved by the starter motor. In this case, the vehicle may not be a hybrid vehicle, or it may be a vehicle equipped only with an engine as a driving power source.

[0070] In the above embodiment, a hybrid vehicle 1 equipped with a first motor 61 and a second motor 62 as driving power sources was described as an example, but it is not limited to this. For example, a hybrid vehicle may also be provided with an engine and a single motor as driving power sources, a motor is provided in the power transmission path between the engine and the drive wheels, a first clutch is provided between the engine and the motor, and a second clutch is provided between the motor and the drive wheels. In this case, the engine can be started by motor driving the engine with the first clutch engaged and the second clutch disengaged.

[0071] The embodiments of the present invention have been described in detail above, but the present invention is not limited to this specific embodiment. Various modifications and alterations can be made within the scope of the spirit of the present invention as set forth in the claims.

[0072] Symbol Explanation

[0073] 1-Hybrid vehicle, 10-Engine, 22-Low-pressure pump, 26-Low-pressure distribution pipe, 27-Intake manifold injection valve, 61-First motor, 90-Battery, 100-ECU (Control unit, start-up control unit, feedback control unit).

Claims

1. A vehicle control device, characterized in that, The vehicle includes: an engine as a power source for driving; a motor drive mechanism capable of driving the engine; and a pump that discharges fuel to the engine. The vehicle control device includes a start control unit that, while the engine is continuously cut off from fuel, maintains the engine speed at a speed higher than the complete combustion speed that would allow the engine to fully combust, and executes high-speed start control to start the engine by initiating fuel injection. and The feedback control unit updates the proportional term and controls the pump's discharge flow rate based on feedback control of a proportional term and an integral term representing the deviation between a target fuel pressure (which is a target value of the fuel pressure supplied to the engine by the pump) and the actual fuel pressure. During the execution of fuel cutoff before the start of fuel injection of the engine by the start control unit, the feedback control unit fixes the integral term at a lower limit value, and updates the integral term after the start control unit starts fuel injection of the engine.

2. The vehicle control device according to claim 1, characterized in that, The feedback control unit fixes the integral term at the lower limit value during the period after the engine speed reaches the full combustion speed (i.e., the time elapsed after the full combustion speed reaches the full combustion speed is less than a predetermined update stop time or during the execution of fuel cutoff before the start of fuel injection by the start control unit). After the time elapsed after the full combustion speed reaches the full combustion speed is longer than the update stop time and fuel injection by the start control unit begins, the integral term is updated. The update stop time in the high-speed start control is shorter than the time from when the engine speed reaches the full detonation speed until fuel injection begins. The start-up control unit selectively executes the high-speed start-up control and the low-speed start-up control to start the engine by initiating fuel injection from the start of the engine's motor drive until the engine speed reaches the full detonation speed.

3. The vehicle control device according to claim 1 or 2, characterized in that, In the high-speed start control, the start control unit maintains the engine speed at an idle speed higher than the full detonation speed by driving the motor based on the motor drive mechanism.

4. The vehicle control device according to claim 1 or 2, characterized in that, The feedback control unit fixes the integral term to the value before the fuel cut-off after the engine starts and during the execution of the fuel cut-off.

5. The vehicle control device according to claim 1 or 2, characterized in that, The motor drive mechanism is a motor that serves as the power source for driving. The pump is a low-pressure pump that dispenses fuel to the intake manifold injection valve of the engine.

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