JP2021063479A - Control device for fuel supply system - Google Patents

Abstract

To provide a control device capable of performing feedback control of feed pressure without using a feed pressure sensor.SOLUTION: A control device 100 includes: a storage device 102 having estimation mapping data stored therein for outputting an estimation value of feed pressure by using pump rotational frequency and a pump electric current as input; and an execution device 101 controlling a feed pump 52 by outputting required pump rotational frequency to a feed pump control device 200. The execution device 101 executes: required pump rotational frequency calculation processing for calculating the required pump rotational frequency; feed pressure estimation processing for calculating the estimation value of the feed pressure by using the estimation mapping data; feed pressure feedback processing for correcting the required pump rotational frequency so as to reduce a difference between the estimation value of the feed pressure and required feed pressure; learning processing for learning the pump electric current and the pump rotational frequency when a relief valve 56 is opened; and updating processing for correcting the estimation mapping data on the basis of a result of the learning processing.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for an engine fuel supply system.

Patent Document 1 is applied to a fuel supply system of an engine including an electric feed pump and a feed pressure sensor for detecting a feed pressure which is a fuel pressure in a low-pressure fuel system sent by the feed pump. A control device for a fuel supply system that operates the power supply of the feed pump according to the detection value of the pressure sensor is described. In this control device, a pressure higher than the minimum pressure that can prevent the generation of vapor in the fuel pipe is set as the target value, and the deviation of the detection value of the feed pressure sensor with respect to the target value is set to be close to zero. The power supply of the feed pump is feedback controlled. As a result, the feed pump can be driven with reduced power consumption within the range where vapor is not generated in the fuel pipe.

Japanese Unexamined Patent Publication No. 2016-56794

In the above control device, a feed pressure sensor is required to perform feedback control of the feed pressure, and the cost increases accordingly.

Hereinafter, means for solving the above problems and their actions and effects will be described.
The control device of the fuel supply system for solving the above problems is an electric feed pump that pumps fuel from the fuel tank and a feed pump control device that controls the power supply to the feed pump so as to realize the required pump rotation speed. A high-pressure fuel pump that pressurizes the fuel pumped from the fuel tank by the feed pump, a delivery pipe that stores the fuel pressurized by the high-pressure fuel pump, and the fuel stored in the delivery pipe of the engine. The valve is opened when the in-cylinder fuel injection valve injected into the cylinder and the feed pressure, which is the fuel pressure in the low-pressure fuel pipe from the feed pump to the high-pressure fuel pump, become equal to or higher than the predetermined valve opening pressure. It is applied to a fuel supply system including a relief valve that returns the fuel in the low pressure fuel pipe to the fuel tank and suppresses an excessive increase in the feed pressure. This control device outputs the estimated value of the feed pressure by inputting the pump rotation speed which is the rotation speed of the impeller of the feed pump per unit time and the pump current which is the current value in the feed pump. Is equipped with a storage device in which is stored. Further, this control device is an execution device that controls the feed pump by outputting the required pump rotation speed to the feed pump control device, and is based on the required feed pressure and the fuel injection amount according to the fuel temperature. The required pump rotation speed calculation process for calculating the required pump rotation speed, the feed pressure estimation process for calculating the estimated value of the feed pressure using the estimation mapping data, and the estimated value calculated through the feed pressure estimation process. When the required pump rotation speed is corrected so as to reduce the deviation from the required feed pressure, and when the required pump rotation speed is gradually increased until the relief valve is opened and the relief valve is opened. It is provided with an execution device that executes a learning process for learning the pump current and the pump rotation speed, and an update process for correcting the estimation mapping data based on the result of the learning process.

The above control device executes the feed pressure feedback process using the estimated value of the feed pressure calculated through the feed pressure estimation process. Therefore, according to this control device, the feed pressure feedback process can be executed without providing the feed pressure sensor. The pump rotation speed and the pump current have a correlation with the work amount of the pump. Further, the fuel temperature has a correlation with the clearance of the parts constituting the feed pump and the viscosity of the fuel. That is, the fuel temperature correlates with the fuel leakage between the parts of the feed pump and the sliding resistance between the parts, which are related to the work efficiency of the feed pump. Therefore, in the above control device, the estimated value of the feed pressure is calculated by using the mapping data for estimation with the pump rotation speed, the pump current, and the fuel temperature as inputs.

However, when calculating the estimated value of the feed pressure using the estimation mapping data prepared in advance, if the type of fuel used changes or the deterioration of the feed pump progresses, the estimation mapping data is used. The estimated value calculated in the above will deviate from the actual fuel pressure. This problem cannot occur when the feed pressure sensor is provided, and is an unavoidable problem in realizing a configuration in which the feed pressure sensor is omitted. In the above-mentioned control device, in order to solve such a problem, a learning process is executed in which the pump rotation speed is increased until the relief valve is opened and the pump current and the pump rotation speed when the relief valve is opened are learned. I am trying to do it. According to this learning process, it is possible to learn the amount of work required to realize a feed pressure equal to the valve opening pressure of the relief valve. Then, the above-mentioned control device executes an update process for correcting the estimation mapping data based on the result of this learning process. Therefore, even if the type of fuel used changes or the deterioration of the feed pump progresses, the influence can be reflected in the estimation mapping data through the learning process and the update process.

Therefore, according to the above control device, it is possible to realize a configuration in which feedback control of the feed pressure is performed in a form corresponding to a change in the type of fuel used, deterioration of the feed pump, etc., without using a feed pressure sensor. it can.

In one aspect of the control device of the fuel supply system, the storage device stores a plurality of the estimation mapping data having different corresponding fuel temperature levels. Then, in this control device, the execution device derives a mapping corresponding to the fuel temperature in the feed pressure estimation process by interpolation from the two estimation mapping data, and the pump rotation speed and the pump are derived from the derived mapping. Input the current and calculate the estimated value of the feed pressure.

Even if the pump speed and pump current are constant, if the fuel temperature is different, the realized feed pressure will be different. The mapping data that outputs the estimated value of the feed pressure by inputting the three variables of the fuel temperature, the pump rotation speed, and the pump current is complicated, and the load required for calculating the estimated value becomes large. On the other hand, in this control device, a plurality of estimation mapping data are stored in the storage device in correspondence with different levels of fuel temperature. Then, the execution device derives a mapping corresponding to the actual fuel temperature by interpolation from two estimation mapping data out of the stored estimation mapping data, and uses the derived mapping to estimate the feed pressure. Is calculated. According to such a configuration, it is possible to suppress the complexity of the mapping data and the increase in the calculation load.

In one aspect of the control device of the fuel supply system in which the map corresponding to the fuel temperature is derived by interpolation from the two estimation map data in the feed pressure estimation process, the execution device is said to be in the update process. The mapping derived by interpolation is corrected so that a value equal to the valve opening pressure is output when the pump rotation speed and the pump current acquired through the learning process are input, and the correction content of the mapping derived by interpolation is corrected. It is reflected in the plurality of estimation mapping data stored in the storage device.

By adopting such a configuration, it is possible to reflect the learning result by the learning process on a plurality of estimation mapping data stored in the storage device, and the learning result is not limited to the fuel temperature when the learning process is executed. It can be reflected.

In one aspect of the control device of the fuel supply system, the executing device executes the learning process when fuel injection is not performed.
According to the above configuration, since the learning process is executed in a state where the fuel injection amount is zero, the learning process can be performed in a stable state where the fuel injection amount does not fluctuate. Therefore, it is possible to perform learning with higher accuracy as compared with the case where the learning process is performed in a state where the fuel injection amount fluctuates.

In one aspect of the control device of the fuel supply system, the execution device determines that an abnormality has occurred when the correction amount of the estimation mapping data by the update process deviates from the permissible range. To execute.

If the amount of correction of the estimation mapping data by the update process is significantly large, it is possible that the state of the fuel supply system, that is, the state of the feed pump, fuel piping, etc., has changed significantly from the initial state. is there. According to the above configuration, it is detected that the state of the fuel supply system has changed significantly based on the correction amount deviating from the permissible range, and it is determined that an abnormality has occurred. Can be done.

In one aspect of the control device of the fuel supply system that executes the determination process, the execution device moves the allowable range in the determination process to the side where the correction amount increases as the integrated operating amount of the feed pump increases.

Deterioration of the feed pump, such as wear of the impeller, gradually progresses as the cumulative operating amount increases. Therefore, according to the above configuration, the allowable range can be moved according to the degree of progress of deterioration. Therefore, it is possible to detect by the determination process that a state deviating from the increase in the correction amount due to the progress of normal deterioration has occurred, and determine the occurrence of an abnormality.

In one aspect of the control device of the fuel supply system that executes the determination process, in the determination process, the correction amount of the estimation mapping data by the update process deviates from the permissible range and refueling. If it is not immediately after, it is determined that an abnormality has occurred, and if the correction amount of the estimation mapping data by the update process deviates from the permissible range and immediately after refueling, it is in the fuel tank. It is determined that the fuel type has been switched.

Even when the type of fuel in the fuel tank is switched by refueling and the viscosity of the fuel changes, the amount of correction of the estimation mapping data by the update process changes significantly. If the correction amount of the estimation mapping data by the update process deviates from the permissible range immediately after refueling, it is highly possible that the type of fuel in the fuel tank has been switched by refueling.

According to the above configuration, it is possible to determine whether the cause of the correction amount deviating from the permissible range is the occurrence of an abnormality or the switching of the fuel type.
In one aspect of the control device of the fuel supply system that determines that the type of fuel has been switched through the determination process, the required pump rotation speed is output to the storage device by inputting the required feed pressure and the fuel injection amount. , A plurality of rotation speed calculation mapping data having different types of corresponding fuels are stored. Then, the execution device calculates the required pump rotation speed using the map data for calculating the rotation speed in the required pump rotation speed calculation process. In this control device, when it is determined in the determination process that the type of fuel has been switched, the execution device switches the mapping data for rotation speed calculation used in the required pump rotation speed calculation process.

According to the above configuration, when it is determined that the fuel type has been switched, the rotation speed calculation mapping data used for the required pump rotation speed calculation process is switched. Therefore, even if the fuel type is switched, a specific fuel type is selected. The required pump rotation speed can be calculated accurately as compared with the case where one type of mapping data for calculating the rotation speed is continuously used for calculating the required pump rotation speed. Further, since the required pump rotation speed can be calculated accurately, the increase in the correction amount of the estimation mapping data due to the switching of the fuel type can be eliminated.

The schematic diagram which shows the structure of the control device of 1st Embodiment and the fuel supply system which is the control target of the control device. The block diagram which shows the flow of the process concerning the feed pressure control executed by the control apparatus of 1st Embodiment. A graph showing the relationship between fuel temperature and required feed pressure. (A) Estimated mapping data corresponding to 25 ° C. (B) Map corresponding to 30 ° C. (C) Estimated mapping data corresponding to 70 ° C. (A) Transition of pump rotation speed in learning process. (B) Transition of feed pressure in learning process. (C) Transition of pump current in learning process. (A) Map before correction. (B) Corrected mapping. (A) Estimated mapping data corresponding to 25 ° C. reflecting the learning result of the learning process. (B) Corrected mapping. (C) Estimated mapping data corresponding to 70 ° C. reflecting the learning result of the learning process. The figure which shows the relationship between the total mileage and the correction amount. A flowchart showing the flow of the determination process. The block diagram which shows the flow of the process which concerns on the feed pressure control in the control apparatus of 2nd Embodiment. The figure which shows the mapping data for rotation speed calculation corresponding to the fuel which has a low volume ratio of ethanol. The figure which shows the mapping data for rotation speed calculation corresponding to the fuel which has a high volume ratio of ethanol. The flowchart which shows the flow of the determination process in the control device of 2nd Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the control device of the fuel supply system will be described in detail with reference to FIGS. 1 to 9.

FIG. 1 shows the configuration of a fuel supply system for an in-vehicle engine to which the control device of the present embodiment is applied. The control device 100 of the present embodiment is applied to a fuel supply system of an in-cylinder injection type in-vehicle engine that injects fuel into a cylinder.

As shown in FIG. 1, the fuel supply system to which the control device 100 is applied includes a feed pump 52 installed inside the fuel tank 51 and a high-pressure fuel pump 60 installed outside the fuel tank 51. There are two fuel pumps. The feed pump 52 is an electric pump that rotates the impeller by a brushless motor. Further, the fuel supply system is provided with a delivery pipe 71 which is a fuel accumulator to which an in-cylinder fuel injection valve 44 provided in each cylinder of the engine is connected. The engine equipped with this fuel supply system is an in-line 4-cylinder engine, and four in-cylinder fuel injection valves 44 are connected to the delivery pipe 71.

The fuel supply system includes a low-pressure fuel pipe 57, which is a fuel passage for sending fuel from the feed pump 52 to the high-pressure fuel pump 60, and a fuel passage for sending fuel from the high-pressure fuel pump 60 to the delivery pipe 71. A high-pressure fuel pipe 72 and a certain high-pressure fuel pipe 72 are provided. The delivery pipe 71 is provided with a fuel pressure sensor 132 that detects the high-pressure side fuel pressure, which is the pressure of the fuel stored inside. The fuel pressure sensor 132 indicates the fuel pressure at a gauge pressure based on the atmospheric pressure.

The feed pump 52 sucks the fuel in the fuel tank 51 through the upstream filter 53 in response to the power supply and sends it to the low pressure fuel pipe 57. In the portion of the low-pressure fuel pipe 57 located inside the fuel tank 51, the pressure of the fuel sent to the low-pressure fuel pipe 57 by the feed pump 52, that is, the feed pressure Pf which is the pressure of the fuel in the low-pressure fuel pipe 57 is defined as default. A relief valve 56 is provided which opens the valve when the valve opening pressure of the above is exceeded and relieves fuel from the low pressure fuel pipe 57 to the fuel tank 51. The low-pressure fuel pipe 57 has a high pressure via a downstream filter 58 that filters impurities in the fuel flowing through the low-pressure fuel pipe 57 and a pulsation damper 61 for reducing the pulsation of the fuel pressure in the low-pressure fuel pipe 57. It is connected to the fuel pump 60.

The high-pressure fuel pump 60 includes a plunger 62, a fuel chamber 63, an electromagnetic spill valve 64, a check valve 65, and a relief valve 66. The plunger 62 is reciprocally driven by a pump cam 67 provided on the camshaft 42 of the engine, and the volume of the fuel chamber 63 is changed according to the reciprocating drive. The fuel chamber 63 is connected to the low pressure fuel pipe 57 via an electromagnetic spill valve 64.

The electromagnetic spill valve 64 closes in response to energization to block the flow of fuel between the fuel chamber 63 and the low-pressure fuel pipe 57, and opens in response to the stop of energization to the fuel chamber 63. Allows the flow of fuel to and from the low pressure fuel pipe 57. The check valve 65 allows the discharge of fuel from the fuel chamber 63 to the delivery pipe 71, while prohibiting the backflow of fuel from the delivery pipe 71 to the fuel chamber 63. The relief valve 66 is provided in a passage bypassing the check valve 65, and opens when the pressure on the delivery pipe 71 side becomes excessively high to allow the backflow of fuel to the fuel chamber 63 side.

The fuel pressurization operation of the high-pressure fuel pump 60 configured as described above will be described. In the high-pressure fuel pump 60, the volume of the fuel chamber 63 changes according to the reciprocating motion of the plunger 62. In the following description, the operation of the plunger 62 in the direction of increasing the volume of the fuel chamber 63 is described as lowering of the plunger 62, and conversely, the operation of the plunger 62 in the direction of decreasing the volume of the fuel chamber 63 is described. Described as an increase in the plunger 62.

In the high-pressure fuel pump 60, when the plunger 62 starts descending with the electromagnetic spill valve 64 opened, fuel flows into the fuel chamber 63 from the low-pressure fuel pipe 57 as the volume of the fuel chamber 63 increases. If the electromagnetic spill valve 64 is maintained in the open state even after the plunger 62 changes from descending to ascending, the fuel that has flowed into the fuel chamber 63 while the plunger 62 is descending is pushed back to the low-pressure fuel pipe 57. When the electromagnetic spill valve 64 is closed while the plunger 62 is ascending, and then the electromagnetic spill valve 64 is kept closed until the plunger 62 changes from ascending to descending, the volume of the fuel chamber 63 accompanying the ascending of the plunger 62 is increased. Due to the reduction, the fuel in the fuel chamber 63 is pressurized. Then, when the fuel pressure in the fuel chamber 63 exceeds the fuel pressure in the high-pressure fuel pipe 72, the check valve 65 opens and the pressurized fuel in the fuel chamber 63 is sent to the high-pressure fuel pipe 72. .. In this way, the high-pressure fuel pump 60 pressurizes the fuel in the low-pressure fuel pipe 57 and sends it to the high-pressure fuel pipe 72 each time the plunger 62 reciprocates. By changing the closing timing of the electromagnetic spill valve 64 while the plunger 62 is rising, the amount of fuel delivered to the high-pressure fuel pipe 72 by the high-pressure fuel pump 60 is increased or decreased for each pressurization operation.

An engine including such a fuel supply system is controlled by the control device 100. The control device 100 is an engine control device and also controls the fuel supply system of the engine. That is, the control device 100 is also a control device for the fuel supply system.

The control device 100 includes an execution device 101 that executes various arithmetic processes, and a storage device 102 that stores control programs and data. Then, the control device 100 controls the engine including the control of the fuel supply system by reading and executing the program stored in the storage device 102 by the execution device 101.

The control device 100 is input with detection signals of various sensors for detecting the operating state of the engine. As shown in FIG. 1, the accelerator position sensor 142 inputs a detection signal of the driver's accelerator operation amount, and the vehicle speed sensor 141 inputs a vehicle speed detection signal which is the traveling speed of the vehicle. There is.

Further, detection signals of various other sensors are input to the control device 100. For example, as shown in FIG. 1, in the control device 100, in addition to the fuel pressure sensor 132 that detects the fuel pressure in the delivery pipe 71, the air flow meter 133, the crank position sensor 134, the cam position sensor 135, and the cooling water temperature sensor 136 is connected.

The air flow meter 133 detects the temperature of the air sucked into the cylinder through the intake passage of the engine and the intake air amount which is the mass of the sucked air. The crank position sensor 134 outputs a crank angle signal according to a change in the rotational phase of the crankshaft, which is the output shaft of the engine. The control device 100 calculates the engine speed, which is the number of revolutions of the crankshaft per unit time, based on the crank angle signal input from the crank position sensor 134.

The cam position sensor 135 outputs a cam angle signal according to a change in the rotation phase of the cam shaft 42. The cooling water temperature sensor 136 detects the cooling water temperature, which is the temperature of the cooling water of the engine.

Further, the control device 100 includes a fuel temperature sensor 137 that detects the fuel temperature Tf, which is the temperature of the fuel in the fuel tank 51, and a fuel temperature sensor 137 that detects the level of the liquid level of the fuel in the fuel tank 51. A fuel level sensor 138 that outputs a detection signal indicating the remaining amount is also connected.

Further, the control device 100 is connected to a feed pump control device 200 that controls the pump rotation speed Np, which is the rotation speed of the impeller of the feed pump 52 per unit time. The feed pump control device 200 increases or decreases the pump rotation speed Np by adjusting the power supplied to the feed pump 52 by pulse width modulation based on a command from the control device 100. The feed pump control device 200 transmits information on the pump current Ip, which is the current supplied to the feed pump 52, and the pump rotation speed Np to the control device 100.

The control device 100 executes fuel injection amount control, fuel pressure variable control, and feed pressure control as part of engine control.
In controlling the fuel injection amount, the control device 100 first calculates the required injection amount, which is a required value of the fuel injection amount of the in-cylinder fuel injection valve 44, according to the engine operating state such as the engine speed and the engine load. Subsequently, the control device 100 calculates the valve opening time of the in-cylinder fuel injection valve 44 required for fuel injection for the required injection amount based on the detected value of the fuel pressure sensor 132. Then, the control device 100 opens the in-cylinder fuel injection valve 44 of each cylinder to inject fuel for a period corresponding to the calculated valve opening time. Further, as a part of the fuel injection control, the control device 100 stops the fuel injection and stops the supply of the fuel to the combustion chamber of the engine during deceleration when the operation amount of the accelerator is "0". It also performs fuel cut control to reduce the fuel consumption rate.

In the variable fuel pressure control, the control device 100 calculates a target value of the fuel pressure on the high pressure side based on the engine load and the like. The target value of the fuel pressure on the high pressure side is basically set to a low pressure when the engine load is low and a high pressure when the engine load is high. Then, the control device 100 adjusts the fuel delivery amount of the high-pressure fuel pump 60 in order to reduce the deviation between the detected value of the high-pressure side fuel pressure by the fuel pressure sensor 132 and the target value of the high-pressure side fuel pressure. Specifically, when the detected value of the high-pressure side fuel pressure is lower than the target value, the valve closing timing of the electromagnetic spill valve 64 during the rising period of the plunger 62 is advanced to reduce the fuel delivery amount of the high-pressure fuel pump 60. increase. When the detected value of the high-pressure side fuel pressure is higher than the target value, the closing timing of the electromagnetic spill valve 64 during the rising period of the plunger 62 is delayed to reduce the fuel delivery amount of the high-pressure fuel pump 60.

Subsequently, the details of the feed pressure control will be described. Feed pressure control is performed for the following purposes. When the fuel sent from the feed pump 52 and flowing through the low-pressure fuel pipe 57 receives the heat of the engine and becomes high in temperature, vapor is generated in the low-pressure fuel pipe 57, and the supply of fuel to the delivery pipe 71 may be delayed. .. The higher the fuel pressure, the higher the fuel vaporization temperature. Therefore, in order to prevent the generation of vapor in the low-pressure fuel pipe 57, the amount of fuel sent from the feed pump 52 to the low-pressure fuel pipe 57 is increased to increase the feed pressure. Pf may be increased. However, if the amount of fuel delivered is increased, the power consumption of the feed pump 52 will increase accordingly. Therefore, in the feed pressure control, the fuel discharge amount of the feed pump 52 is adjusted in order to maintain the feed pressure Pf at a low pressure as much as possible to prevent the generation of vapor, thereby suppressing the generation of vapor while suppressing the power consumption. It is preventing.

FIG. 2 shows a flow of processing related to feed pressure control executed by the execution device 101 of the control device 100. As shown in FIG. 2, the feed pressure control is performed through each of the required feed pressure calculation process M200, the required pump rotation speed calculation process M210, the feed pressure estimation process M220, and the feed pressure feedback process M230.

In the required feed pressure calculation process M200, the execution device 101 calculates the required feed pressure Pf *, which is a target value of the feed pressure Pf, based on the fuel temperature Tf detected by the fuel temperature sensor 137.

As shown by the alternate long and short dash line in FIG. 3, the control device 100 switches the required feed pressure Pf * in three stages according to the fuel temperature Tf. In FIG. 3, in addition to the required feed pressure Pf * shown by the two-dot chain line, the relationship between the saturated vapor pressure of the fuel and the fuel temperature is shown by a solid line, a one-dot chain line, and a broken line. The solid line shows the relationship between the saturated vapor pressure of gasoline and the fuel temperature, and the one-point chain line shows the saturated vapor pressure and fuel temperature of the E20 fuel containing 20% of ethanol in volume ratio among the mixed fuels of gasoline and ethanol. Shows the relationship with. Further, the broken line shows the relationship between the saturated vapor pressure of the M15 fuel containing 15% of methanol in the volume ratio and the fuel temperature among the mixed fuels of gasoline and methanol.

In the control device 100, the fuel temperature is such that the required feed pressure Pf * does not fall below the saturated vapor pressure even when the fuel having the highest saturated vapor pressure is used among the fuels expected to be used. The higher the Tf, the higher the required feed pressure Pf *. Specifically, in the required feed pressure calculation process M200, the execution device 101 calculates "P1" as the required feed pressure Pf * when the fuel temperature Tf is less than "T1" as shown in FIG. Then, when the fuel temperature Tf is equal to or higher than “T1” and less than “T2” higher than “T1”, the execution device 101 calculates “P2” higher than “P1” as the required feed pressure Pf *. .. Further, when the fuel temperature Tf is "T2" or higher, the execution device 101 calculates "P3" as the required feed pressure Pf *, which is higher than "P2" and slightly lower than the valve opening pressure Px of the relief valve 56. ..

In the required pump rotation speed calculation process M210, the execution device 101 uses the fuel injection amount Q and the required feed pressure Pf * calculated through the required feed pressure calculation process M200 to determine the required pump that is the target value of the pump rotation speed Np. Calculate the rotation speed Np *. The fuel injection amount Q can be grasped based on the required injection amount calculated through the required injection amount calculation process M100 executed as a part of the fuel injection amount control.

In the control device 100, in the required pump rotation speed calculation process M210, the execution device 101 takes into consideration the amount of fuel consumed by executing the fuel injection control, and the pump rotation speed Np required to realize the required feed pressure Pf *. Is calculated as the required pump rotation speed Np *.

Specifically, the execution device 101 calculates the required pump rotation speed Np * using the rotation speed calculation mapping data stored in the storage device 102. As shown in FIG. 2, the rotation speed calculation mapping data is an arithmetic map that outputs the required pump rotation speed Np * by inputting the required feed pressure Pf * and the fuel injection amount Q. This calculation map is created so that the required pump rotation speed Np * can be calculated based on the result of an experiment using gasoline as fuel, for example. FIG. 2 illustrates the contour lines of the required pump rotation speed Np *. In this calculation map, the higher the required feed pressure Pf * and the larger the fuel injection amount Q, the larger the output required pump rotation speed Np *.

In the feed pressure estimation process M220, the execution device 101 calculates an estimated value of the feed pressure Pf based on the pump rotation speed Np and the pump current Ip received from the feed pump control device 200 and the fuel temperature Tf.

Specifically, the execution device 101 calculates an estimated value of the feed pressure Pf using the estimation mapping data stored in the storage device 102. As shown in FIG. 2, the estimation mapping data is an arithmetic map that outputs the feed pressure Pf by inputting the pump rotation speed Np and the pump current Ip. The storage device 102 stores, as estimation mapping data, three arithmetic maps having different levels of corresponding fuel temperatures Tf. The three calculation maps are, for example, a calculation map corresponding to "-30 ° C", a calculation map corresponding to "70 ° C", and a calculation map corresponding to "25 ° C", respectively, under the usage environment of the vehicle. It is a calculation map corresponding to the lower limit, the upper limit, and the vicinity of the center of the fuel temperature assumed in.

Each of these calculation maps is created so that the feed pressure Pf can be calculated based on the result of an experiment using gasoline having a corresponding fuel temperature Tf as a fuel, for example. FIG. 3 illustrates the contour lines of the feed pressure Pf. In this calculation map, the higher the pump rotation speed and the larger the pump current, the higher the output feed pressure Pf.

In the feed pressure estimation process M220, first, the execution device 101 derives a map corresponding to the current fuel temperature Tf by using two calculation maps among the calculation maps stored in the storage device 102.

For example, as shown in FIG. 4, when the current fuel temperature Tf is 30 ° C., the estimation mapping data corresponding to 25 ° C. lower than 30 ° C. and the estimation mapping data corresponding to 70 ° C. higher than 30 ° C. A map corresponding to 30 ° C. is derived from the data. Here, the mapping corresponding to 30 ° C. is derived by linear interpolation. As shown in FIG. 4A, in the estimation mapping data corresponding to 25 ° C., the feed pressure Pf is 250 kPa when the pump rotation speed Np is 3000 rpm and the pump current Ip is 4 A. On the other hand, as shown in FIG. 4C, in the estimation mapping data corresponding to 70 ° C., the feed pressure Pf is 200 kPa when the pump rotation speed Np is 3000 rpm and the pump current Ip is 4 A. .. Therefore, the execution device 101 calculates the feed pressure Pf when the pump rotation speed Np is 3000 rpm and the pump current Ip is 4 A by linear interpolation. Then, as shown in FIG. 4B, the feed pressure Pf output when the pump rotation speed Np is 3000 rpm and the pump current Ip is 4 A becomes 244.4 kPa calculated by linear interpolation. Derivation of the mapping. By performing linear interpolation in the same manner for other states in which the combination of the pump rotation speed Np and the pump current Ip is different, a mapping corresponding to 30 ° C. can be derived. In this embodiment, since the valve opening pressure Px of the relief valve 56 is 500 kPa, 500 kPa is the upper limit of the feed pressure Pf in FIG.

In the feed pressure estimation process M220, the execution device 101 calculates the estimated value of the current feed pressure Pf by inputting the current pump rotation speed Np and the pump current Ip into the map thus derived by interpolation.

In the feed pressure feedback process M230, the execution device 101 pumps the request based on the request feed pressure Pf * calculated through the request feed pressure calculation process M200 and the estimated value of the feed pressure Pf calculated through the feed pressure estimation process M220. The correction amount ΔN of the rotation speed Np * is calculated. Specifically, in the feed pressure feedback process M230, the execution device 101 increases the correction amount ΔN by a predetermined amount when the estimated value of the feed pressure Pf is smaller than the required feed pressure Pf *. On the other hand, when the estimated value of the feed pressure Pf is larger than the required feed pressure Pf *, the execution device 101 reduces the correction amount ΔN by a predetermined amount. Then, the execution device 101 adds the calculated correction amount ΔN to the required pump rotation speed Np * calculated through the required pump rotation speed calculation process M210 to correct the required pump rotation speed Np *. As a result, the required pump rotation speed Np * after being corrected by the correction amount ΔN thus calculated through the feed pressure feedback process M230 is input to the feed pump control device 200. Then, the feed pump control device 200 controls the power supply to the feed pump 52 so as to realize the input required pump rotation speed Np *.

When the required pump rotation speed Np * is increased, the amount of fuel discharged from the feed pump 52 increases per unit time, so that the feed pressure Pf increases. On the other hand, if the required pump rotation speed Np * is reduced, the amount of fuel discharged from the feed pump 52 per unit time is reduced, so that the feed pressure Pf is lowered. That is, the feed pressure feedback process M230 is a process of correcting the required pump rotation speed Np * so as to reduce the deviation between the estimated value and the required feed pressure Pf *.

As described above, in the fuel supply system of this embodiment, the estimated value of the feed pressure Pf is calculated based on the fuel temperature Tf, the pump rotation speed Np, and the pump current Ip without providing the sensor for detecting the feed pressure Pf. The feed pressure Pf is feedback-controlled using the calculated estimated value.

By the way, when calculating the estimated value of the feed pressure Pf using the estimation mapping data prepared in advance, when the type of fuel used changes or the deterioration of the feed pump 52 progresses, the estimation mapping data The estimated value calculated using the above deviates from the actual feed pressure Pf.

Therefore, in the control device 100, a learning process is performed in which the rotation speed of the feed pump 52 is gradually increased until the relief valve 56 is opened to learn the pump current Ip and the pump rotation speed Np when the relief valve 56 is opened. I'm trying to do it.

Next, this learning process will be described with reference to FIGS. 5 to 7. The learning process is executed by the execution device 101 of the control device 100 when the fuel injection is stopped by the fuel cut control.

FIG. 5 (a) shows the transition of the pump rotation speed in the learning process, FIG. 5 (b) shows the transition of the feed pressure in the learning process, and FIG. 5 (c) shows the transition of the pump current in the learning process. When the learning process is started at time t1, the execution device 101 gradually increases the required pump rotation speed Np * at a constant speed. As a result, the pump rotation speed Np and the pump current Ip gradually increase as shown in FIGS. 5 (a) and 5 (c), and the feed pressure Pf gradually increases as shown in FIG. 5 (b). ..

Then, when the feed pressure Pf reaches the valve opening pressure Px of the relief valve 56 at time t2, the relief valve 56 opens. When the relief valve 56 is opened in this way, the feed pressure Pf does not increase even if the pump rotation speed Np increases. Further, since the relief valve 56 is open, the load on the feed pump 52 is smaller than that before the time t2 when the relief valve 56 was closed, and the required pump rotation speed Np * is realized after the time t2. The rate of increase of the pump current Ip is reduced.

The execution device 101 determines that the time t2 is the time when the feed pressure Pf reaches the valve opening pressure Px based on the change in the change rate of the pump current Ip, and determines that the pump rotation speed Np and the pump current Ip at the time t2. As a learning value. That is, the value "Ix" of the pump current Ip indicated by the point X is acquired in FIG. 5, and the value "Nx" of the pump rotation speed Np indicated by the point Y is acquired.

The execution device 101 executes an update process for updating the estimation mapping data based on the learning value acquired in this way. In the update process, first, the mapping derived by interpolation is corrected as shown in FIG. FIG. 6A shows a map corresponding to 30 ° C. derived by the same interpolation as in FIG. 4B. In FIG. 6, an example of correcting this mapping will be described.

Here, it is assumed that the learning process is performed in a state where the relief valve 56 is assumed to be opened in the state surrounded by the thick line in FIG. 6A. That is, when the pump current Ip is 7A and the pump rotation speed Np reaches 6000 rpm, the feed pressure Pf reaches 500 kPa and the learning process is performed in a state where it is assumed that the relief valve 56 opens. And.

When it is learned by the learning process that the pump current Ip when the relief valve 56 is opened is 7.1 A and the pump rotation speed Np when the relief valve 56 is opened is 6100 rpm, the execution device 101 Corrects the mapping shown in FIG. 6A as shown in FIG. 6B. That is, the mapping is corrected so that a value equal to the valve opening pressure Px is output when the pump rotation speed Np and the pump current Ip acquired through the learning process are input. Specifically, since the pump current Ip when the relief valve 56 is opened is "+ 0.1 A" and the pump rotation speed is deviated by "+ 100 rpm", the input of the pump current Ip for obtaining the same output is "0". The mapping is corrected so that the pump rotation speed increases by "1A" and "100rpm".

The pump current Ip and pump rotation speed Np required to open the relief valve 56 increase in this way because the impeller of the feed pump 52 wears and the clearance between parts increases. This is a case where the work load of the feed pump 52 required to realize the valve opening pressure Px is increased.

Next, as shown in FIG. 7, the execution device 101 reflects the correction content of the map derived by interpolation in the estimation map data stored in the storage device 102. Here, the estimation mapping data corresponding to 25 ° C. shown in FIG. 7A and the estimation mapping data corresponding to 70 ° C. shown in FIG. 7C used when deriving the mapping corresponding to 30 ° C. are used. An example of reflecting the content of the correction will be described.

The higher the fuel temperature Tf, the lower the viscosity of the fuel, which makes it more susceptible to the increased clearance between the parts, increasing the workload of the feed pump 52 required to achieve the valve opening pressure Px. Cheap. In the update process, in order to reflect this tendency, the higher the fuel temperature Tf, the higher the pump rotation speed Np for achieving the valve opening pressure Px. The correction content is reflected in the estimation mapping data corresponding to 25 ° C. and the estimation mapping data corresponding to 70 ° C.

Specifically, the adjustment ratio for adjusting the amount of correction to be reflected according to the degree of deviation between the corresponding temperature of the map derived by interpolation and the corresponding temperature of the estimation mapping data that reflects the correction content is calculated. Then, the correction amount applied to the map derived by interpolation is adjusted using this adjustment ratio and reflected in the two estimation map data.

The adjustment ratio is the difference between the fuel temperature Tf corresponding to the target estimation mapping data and the fuel temperature Tf corresponding to the mapping derived by interpolation, and the difference between the fuel temperature Tf corresponding to the two estimation mapping data. It is a broken quotient. That is, the adjustment ratio used for the estimation mapping data corresponding to 25 ° C. is (30 ° C.-25 ° C.) / (70 ° C.-25 ° C.) = 0.11. The adjustment ratio used for the estimation mapping data corresponding to 70 ° C. is (70 ° C.-30 ° C.) / (70 ° C.-25 ° C.) = 0.89.

Using this adjustment ratio, the execution device 101 uses this adjustment ratio to obtain a mapping derived by interpolation for a value corresponding to the axis label of the pump rotation speed Np for the calculation map corresponding to 25 ° C. on the low temperature side. A correction is made by adding "+89 rpm", which is obtained by subtracting "11 rpm", which is the product of the same correction amount multiplied by the adjustment ratio, from "+100 rpm" which is equal to the correction amount. As a result, the estimation mapping data corresponding to 25 ° C. is updated to the state shown in FIG. 7A.

Then, the execution device 101 has the same amount of correction for the mapping derived by interpolation for the value corresponding to the label of the axis of the pump rotation speed Np for the calculation map corresponding to 70 ° C. on the high temperature side. A correction is made by adding "+1189 rpm", which is obtained by adding "89 rpm", which is the product of the same correction amount multiplied by the adjustment ratio, from "+100 rpm". As a result, the estimation mapping data corresponding to 70 ° C. is updated to the state shown in FIG. 7 (c).

Since the absolute value of the correction amount for the value corresponding to the axis label of the pump current Ip is small, the learning process in this embodiment does not adjust any of the estimation mapping data by the adjustment ratio. Is corrected by the same amount as the mapping derived by interpolation.

By such an update process, the characteristics related to the drive of the feed pump 52 at the time when the learning process is executed and the learning value is acquired can be learned and reflected in the estimation mapping data.
In the vehicle equipped with the fuel supply system of this embodiment, the learning process is executed at the time of shipment from the factory to learn the characteristics at the time of shipment from the factory. Therefore, the magnitude of the variation in characteristics at the time of shipment from the factory due to the tolerance of parts is recorded as a correction amount in the estimation mapping data.

Deterioration such as wear of the impeller in the feed pump 52 progresses as the operating amount of the feed pump 52 increases. FIG. 8 shows the relationship between the correction amount for the value corresponding to the label of the axis of the pump rotation speed Np in the calculation map corresponding to 25 ° C. and the integrated mileage of the vehicle. Since the deterioration progresses as the operating amount of the feed pump 52 increases, the correction amount in the estimation mapping data increases as the integrated mileage of the vehicle increases. The initial value Z of the correction amount in FIG. 8 indicates the correction amount recorded by the learning process at the time of shipment from the factory.

The execution device 101 of the control device 100 executes a determination process for determining an abnormality of the feed pump 52 by utilizing the relationship between the operating amount of the feed pump 52 and the increase in the correction amount.
The execution device 101 executes the determination process shown in FIG. 9 when the estimation mapping data is updated by the learning process. When this determination process is started, the execution device 101 first, in the process of step S100, corrects in the calculation map corresponding to 25 ° C. in order to determine whether or not the correction amount of the estimation mapping data deviates from the permissible range. It is determined whether or not the deviation between the amount and the reference value is equal to or greater than the threshold value α. The reference value is calculated each time the determination process is performed based on the standard inclination data of the correction amount that increases according to the integrated mileage and the initial value Z acquired by the learning process at the time of shipment from the factory. That is, in the process of step S100, as shown by the point P in FIG. 8, the execution device 101 calculates a standard correction amount at the integrated mileage “d1” at the time of execution of the determination process as a reference value, and performs the learning process. It is determined whether or not the magnitude of the deviation from the correction amount updated by is equal to or greater than the threshold value α. The threshold value α is a value that determines the width of the allowable range. That is, the permissible range is a range having a width of a threshold value α above and below the reference value indicated by the point P in FIG.

When it is determined in the process of step S100 that the deviation between the correction amount in the calculation map and the reference value is equal to or greater than the threshold value α (step S100: YES), the execution device 101 advances the process to step S200. Then, the execution device 101 determines that the correction amount of the estimation mapping data deviates from the permissible range, and determines that an abnormality has occurred in the feed pump 52 in the process of step S200.

As shown in FIG. 1, the control device 100 is connected to a warning display unit 110 that displays an icon as information indicating that an abnormality has occurred and notifies the occupant that an abnormality has occurred. ing. When the execution device 101 determines the abnormality, the control device 100 causes the warning display unit 110 to display an icon indicating that an abnormality has occurred. When the process of step S200 is executed, the execution device 101 ends the determination process.

On the other hand, in the process of step S100, when it is determined that the deviation between the correction amount in the calculation map and the reference value is less than the threshold value α (step S100: NO), the execution device 101 corrects the estimation mapping data. Assuming that the amount does not deviate from the permissible range, the determination process is terminated as it is without executing the process of step S200.

The operation of this embodiment will be described.
In the control device 100, the execution device 101 executes the feed pressure feedback process M230 using the estimated value of the feed pressure Pf calculated through the feed pressure estimation process M220. Therefore, the feed pressure feedback process M230 can be executed without providing the feed pressure sensor. The pump rotation speed Np and the pump current Ip have a correlation with the work amount of the feed pump 52. Further, the fuel temperature Tf has a correlation with the clearance of the parts constituting the feed pump 52 and the viscosity of the fuel. That is, the fuel temperature Tf has a correlation with fuel leakage from the parts of the feed pump 52 and sliding resistance between the parts, which are related to the work efficiency of the feed pump 52. Therefore, in the control device 100, the estimated value of the feed pressure Pf is calculated using the mapping data for estimation by inputting the pump rotation speed Np, the pump current Ip, and the fuel temperature Tf. Then, in this control device 100, a learning process is executed in which the rotation speed of the pump is increased until the relief valve 56 opens, and the pump current Ip and the pump rotation speed Np when the relief valve 56 opens are learned. .. According to this learning process, it is possible to learn the amount of work required to realize the feed pressure Pf equal to the valve opening pressure Px of the relief valve 56. Then, the control device 100 executes an update process for correcting the estimation mapping data based on the result of this learning process. Therefore, even if the type of fuel used changes or the deterioration of the feed pump 52 progresses, the influence can be reflected in the estimation mapping data through the learning process and the update process.

As a method of learning the characteristics related to the drive of the feed pump 52, the feed pump 52 is driven in a state where the fuel pressure in the delivery pipe 71 is lowered to the feed pressure Pf, and the fuel pressure in the delivery pipe 71 is detected. A method of learning the characteristics related to the drive of the feed pump 52 by using the detected value of the pressure sensor 132 is also conceivable. However, in order to perform learning by such a method, the fuel pressure in the delivery pipe 71 must be reduced to the feed pressure Pf. On the other hand, according to the learning process in the above embodiment, the learning process can be performed without needing to reduce the fuel pressure in the delivery pipe 71 to the feed pressure Pf.

Further, as a learning process for learning the state at the time when the valve opening pressure Px of the relief valve 56 is reached, it is possible to adopt a configuration in which a detection means for physically detecting the opening of the relief valve 56 is provided. On the other hand, according to the learning process in the above embodiment, the pump current Ip that can be detected by the feed pump control device 200 is monitored without providing a detection means or the like that physically detects the opening of the relief valve 56. This makes it possible to detect the opening of the relief valve 56. Therefore, it is not necessary to newly add a means for detecting the opening of the relief valve 56.

The effect of this embodiment will be described.
(1) Without using a feed pressure sensor, it is possible to realize a configuration in which feedback control of the feed pressure Pf is performed in a form corresponding to a change in the type of fuel used, deterioration of the feed pump 52, and the like.

(2) Even if the pump rotation speed Np and the pump current Ip are constant, if the fuel temperature Tf is different, the realized feed pressure Pf will be different. The mapping data that outputs the estimated value of the feed pressure Pf by inputting the three variables of the fuel temperature Tf, the pump rotation speed Np, and the pump current Ip is complicated, and the load required for calculating the estimated value becomes large. On the other hand, in the control device 100, a plurality of estimation mapping data are stored in the storage device 102 in correspondence with different levels of fuel temperature Tf. Then, the execution device 101 derives a mapping corresponding to the actual fuel temperature Tf by interpolation from two estimation mapping data among the stored estimation mapping data, and uses the derived mapping to feed pressure Pf. Calculate the estimated value of. Therefore, it is possible to suppress the complexity of the mapping data and the increase in the calculation load.

(3) In the control device 100, the execution device 101 is interpolated so that a value equal to the valve opening pressure Px is output when the pump rotation speed Np and the pump current Ip acquired through the learning process are input in the update process. Correct the derived mapping. Then, the correction content of the map derived by interpolation is reflected in the plurality of estimation map data stored in the storage device 102. Therefore, the learning result of the learning process can be reflected in the plurality of estimation mapping data stored in the storage device 102. Therefore, the learning result can be reflected regardless of the fuel temperature Tf when the learning process is executed.

(4) In the control device 100, the execution device 101 executes the learning process during the fuel cut in which the fuel injection is not performed. Therefore, the learning process is executed in a state where the fuel injection amount Q is zero, and the learning process can be performed in a stable state where the fuel injection amount Q does not fluctuate. Therefore, it is possible to perform learning with higher accuracy as compared with the case where the learning process is performed in a state where the fuel injection amount Q is fluctuating.

(5) When the correction amount of the estimation mapping data by the update process is remarkably large, the state of the fuel supply system, that is, the state of the feed pump 52, the low-pressure fuel pipe 57, etc., changes significantly from the initial state. It may have been closed. According to the control device 100, in the determination process, it is determined that the correction amount deviates from the permissible range based on the deviation amount between the correction amount of the estimation mapping data and the reference value being equal to or more than the threshold value α. ing. Therefore, based on this determination, it is possible to detect that the state of the fuel supply system has changed significantly and determine that an abnormality has occurred.

(6) Deterioration of the feed pump 52, such as wear of the impeller, gradually progresses as the cumulative operating amount increases. On the other hand, in the determination process in the control device 100, the permissible range is moved to the side where the correction amount is large as the total mileage of the vehicle increases. Therefore, the permissible range can be moved according to the degree of progress of deterioration. Therefore, according to the control device 100, it is possible to detect by the determination process that a state deviating from the increase in the correction amount due to the progress of normal deterioration has occurred, and determine the occurrence of an abnormality.

(Second Embodiment)
Next, a second embodiment of the control device of the fuel supply system will be described with reference to FIGS. 10 to 13.

The control device 100 of the second embodiment has the same structure as the control device 100 of the first embodiment. The same parts as those in the first embodiment are designated by the same reference numerals, and the differences will be mainly described.
As shown in FIG. 10, the control device 100 of the second embodiment also has the required feed pressure calculation process M200, the required pump rotation speed calculation process M210, the feed pressure estimation process M220, and the feed pressure feedback process M230 as part of the feed pressure control. To execute. Further, the control device 100 of the second embodiment executes the same learning process and update process as the control device 100 of the first embodiment.

As shown in FIG. 2, the storage device 102 in the control device 100 of the second embodiment has a plurality of rotation speeds of different types of fuels as the rotation speed calculation mapping data used in the required pump rotation speed calculation process M210. The map data for calculation is stored. For example, in the storage device 102, in addition to the map data for calculating the number of rotations corresponding to gasoline, as the mapping data for calculating the number of rotations corresponding to the mixed fuel of ethanol and gasoline, a plurality of rotation speed calculations having different volume ratios of ethanol Mapping data is stored.

The difference between the mapping data for calculating the rotation speed will be described with reference to FIGS. 11 and 12.
The rotation speed calculation mapping data shown in FIG. 11 is rotation speed calculation mapping data corresponding to a fuel having a small volume ratio of ethanol, and the rotation speed calculation mapping data shown in FIG. 12 is a fuel with a large volume ratio of ethanol. It is the mapping data for calculating the rotation speed corresponding to.

In the estimation mapping data corresponding to the fuel having a small volume ratio of ethanol shown in FIG. 11, when the fuel injection amount Q is “Q1” and the required feed pressure Pf * is the feed pressure “P1”, the required pump The rotation speed Np * is calculated as "3000 rpm".

On the other hand, in the estimation mapping data corresponding to the fuel having a large volume ratio of ethanol shown in FIG. 12, when the fuel injection amount Q is “Q1” and the required feed pressure Pf * is the feed pressure “P1”. , The required pump rotation speed Np * is calculated as "2500 rpm".

The larger the volume ratio of ethanol, the higher the viscosity. Therefore, when a fuel having a large volume ratio of ethanol is used, the fuel is less likely to leak from the clearance between the parts of the feed pump 52. Therefore, when a fuel having a large volume ratio of ethanol is used, the same feed pressure Pf can be realized at a lower pump rotation speed Np than when a fuel having a small volume ratio of ethanol is used.

The storage device 102 in the control device 100 of the second embodiment stores a plurality of rotation speed calculation mapping data corresponding to the different types of fuel in consideration of the influence of the difference in the type of fuel.

In the control device 100 of the second embodiment, not only the abnormality determination but also the switching of the fuel type is determined through the determination process, and when the switching of the fuel type is determined, the rotation used in the required pump rotation speed calculation process M210. The mapping data for number calculation is switched.

Next, the determination process in the control device 100 of the second embodiment will be described with reference to FIG.
The execution device 101 in the control device 100 of the second embodiment executes the determination process shown in FIG. 13 when the estimation mapping data is updated by the learning process. When this determination process is started, the execution device 101 first determines in the process of step S100 whether or not the deviation between the correction amount in the calculation map of the estimation mapping data corresponding to 25 ° C. and the reference value is equal to or greater than the threshold value α. judge.

When it is determined in the process of step S100 that the deviation between the correction amount in the calculation map and the reference value is less than the threshold value α (step S100: NO), the execution device 101 ends this determination process as it is.

On the other hand, in the process of step S100, when it is determined that the deviation between the correction amount in the calculation map and the reference value is equal to or greater than the threshold value α (step S100: YES), the execution device 101 shifts the process to step S150. Proceed. Then, the execution device 101 determines whether or not it is immediately after refueling in the process of step S150. It should be noted that the determination as to whether or not refueling has been performed is performed based on the change in the detected value of the fuel level sensor 138. When the detection value of the fuel level sensor 138 becomes larger than a certain amount, the execution device 101 determines that refueling has been performed, and if it is the first determination process after determining that refueling has been performed, in step S150. Judge that it is just after refueling.

If it is determined in the process of step S150 that it is not immediately after refueling (step S150: NO), the execution device 101 advances the process to step S200. Then, the execution device 101 determines in the process of step S200 that an abnormality has occurred in the feed pump 52. When the process of step S200 is executed, the execution device 101 ends the determination process.

On the other hand, if it is determined in the process of step S150 that the process has just been refueled (step S150: YES), the execution device 101 advances the process to step S300. Then, the execution device 101 makes a fuel type switching determination to the effect that the type of fuel used has been switched in the process of step S300.

When the fuel type switching determination is performed, the execution device 101 switches the rotation speed calculation mapping data used in the required pump rotation speed calculation process M210. Specifically, when the correction amount is larger than the reference value and the deviation amount is equal to or higher than the threshold value α, the pump rotation speed Np for achieving the same feed pressure Pf is large. Therefore, it can be determined that the fuel has been switched to a fuel having a low viscosity. Therefore, in this case, the data is switched to the rotation speed calculation mapping data corresponding to the fuel having a smaller volume ratio of ethanol than the rotation speed calculation mapping data used.

On the contrary, when the correction amount is smaller than the reference value and the deviation amount is equal to or more than the threshold value α, the pump rotation speed Np for achieving the same feed pressure Pf is small. It can be judged that the fuel has been switched to a highly viscous fuel. Therefore, in this case, the data is switched to the rotation speed calculation mapping data corresponding to the fuel having a larger volume ratio of ethanol than the rotation speed calculation mapping data used.

When the process of step S300 is executed, the execution device 101 ends the determination process.
The operation of the second embodiment will be described.
Even when the type of fuel in the fuel tank 51 is switched by refueling and the viscosity of the fuel changes, the amount of correction of the estimation mapping data by the update process changes significantly. If the correction amount of the estimation mapping data by the update process becomes large immediately after refueling, it is highly possible that the type of fuel in the fuel tank has been switched by refueling. Therefore, in the control device 100 of the second embodiment, when the deviation amount between the correction amount and the reference value becomes the threshold value α or more (S100: YES) in the determination process, it is determined whether or not it is immediately after refueling. (Step S150), and if it is immediately after refueling, the fuel type switching determination (S300) is performed. As a result, in the control device 100, when the type of fuel is switched, the rotation speed calculation mapping data used in the required pump rotation speed calculation process M210 is switched.

The effect of the second embodiment will be described. According to the control device 100 of the second embodiment, the following effects can be obtained in addition to the effects (1) to (6) of the first embodiment.
(7) It is possible to determine whether the cause of the correction amount due to the update process deviating from the permissible range is the occurrence of an abnormality or the switching of the fuel type.

(8) In the control device 100 of the second embodiment, when it is determined that the type of fuel has been switched, the rotation speed calculation mapping data used in the required pump rotation speed calculation process M210 is switched. Therefore, even if the fuel type is switched, the required pump rotation is more accurate than when one type of rotation speed calculation mapping data corresponding to a specific fuel type is continuously used for calculating the required pump rotation speed Np *. The number Np * can be calculated. Further, since the required pump rotation speed Np * is calculated accurately, the increase in the correction amount of the estimation mapping data due to the switching of the fuel type can be eliminated.

Each of the above embodiments can be modified and implemented as follows. The following modification examples can be implemented in combination with each other to the extent that they are technically consistent.
The mapping data stored in the storage device 102 does not have to be an arithmetic map. For example, it may be a function. The coefficient of the function stored in the storage device may be corrected according to the result of the learning process.

-Although an example of deriving a mapping corresponding to the current fuel temperature Tf by interpolation from a plurality of estimation mapping data has been shown, this mode may not be used. For example, the required pump rotation speed Np * may be calculated using one estimation mapping data with the fuel temperature Tf as an input in addition to the fuel injection amount Q and the required feed pressure Pf *.

-The mode of correcting the map by the update process described with reference to FIG. 6 may be changed as appropriate. In the update process, the mapping may be corrected so that the estimated values of the feed pressure Pf output when the pump rotation speed Np and the pump current Ip acquired by the learning process are input are closer to the valve opening pressure Px.

-The mode of reflecting the learning result in the estimation mapping data in the update process may be changed as appropriate. For example, similar to the correction for the pump current Ip, any estimation mapping data may be corrected by the same amount as the mapping derived by interpolation.

-In the update process, it may be possible to update only the map used when the learning process is executed without reflecting it on the map corresponding to the other fuel temperature Tf.
-Although the example in which the fuel temperature Tf is detected by the fuel temperature sensor 137 is shown, the fuel temperature Tf may be obtained by estimation.

-The conditions for executing the learning process may be changed as appropriate. For example, since the fuel injection amount Q is relatively stable during idle operation, the learning process may be executed during idle operation.

-The conditions for performing the abnormality determination in the determination process are not limited to the embodiments shown in the above embodiment. For example, when the correction amount of the map derived by interpolation exceeds the threshold value, the abnormality determination may be performed. Further, in this case, if a configuration is adopted in which the threshold value is increased as the integrated operating amount of the feed pump 52 increases, the threshold value can be set according to the degree of progress of deterioration.

-The judgment process may be omitted.
-Although an example of using the integrated mileage of the vehicle as an index value of the integrated operating amount of the feed pump 52 is shown, the integrated operating amount itself may be calculated and used. Further, as the index value of the integrated operating amount, an integrated value of the refueling amount calculated based on the detected value of the fuel level sensor 138, an integrated value of the engine operating time, an integrated intake air amount of the engine, or the like may be used. ..

42 ... cam shaft, 44 ... in-cylinder fuel injection valve, 51 ... fuel tank, 52 ... feed pump, 53 ... upstream filter, 56 ... relief valve, 57 ... low pressure fuel piping, 58 ... downstream filter, 60 ... high pressure fuel Pump, 61 ... pulsation damper, 62 ... plunger, 63 ... fuel chamber, 64 ... electromagnetic spill valve, 65 ... check valve, 66 ... relief valve, 67 ... pump cam, 71 ... delivery pipe, 72 ... high pressure fuel piping, 100 ... Control device, 101 ... Execution device, 102 ... Storage device, 110 ... Warning display, 132 ... Fuel pressure sensor, 133 ... Air flow meter, 134 ... Crank position sensor, 135 ... Cam position sensor, 136 ... Cooling water temperature sensor, 137 ... Fuel temperature sensor, 138 ... fuel level sensor, 141 ... vehicle speed sensor, 142 ... accelerator position sensor, 200 ... feed pump control device.

Claims (8)

An electric feed pump that pumps fuel from the fuel tank, a feed pump control device that controls the power supplied to the feed pump so as to achieve the required pump rotation speed, and fuel pumped from the fuel tank by the feed pump. A high-pressure fuel pump that pressurizes, a delivery pipe that stores the fuel pressurized by the high-pressure fuel pump, an in-cylinder fuel injection valve that injects the fuel stored in the delivery pipe into the cylinder of the engine, and the feed pump. When the feed pressure, which is the fuel pressure in the low-pressure fuel pipe from to the high-pressure fuel pump to the high-pressure fuel pump, becomes equal to or higher than the predetermined valve opening pressure, the valve is opened and the fuel in the low-pressure fuel pipe is returned to the fuel tank. Applied to fuel supply systems equipped with a relief valve that suppresses excessive rise in feed pressure,
The estimation mapping data that outputs the estimated value of the feed pressure by inputting the pump rotation speed which is the rotation speed of the impeller of the feed pump per unit time and the pump current which is the current value in the feed pump is stored. Storage device and
It is an execution device that controls the feed pump by outputting the required pump rotation speed to the feed pump control device, and calculates the required pump rotation speed based on the required feed pressure and the fuel injection amount according to the fuel temperature. The required pump rotation speed calculation process, the feed pressure estimation process for calculating the estimated value of the feed pressure using the estimation mapping data, and the deviation between the estimated value calculated through the feed pressure estimation process and the required feed pressure are calculated. Feed pressure feedback processing that corrects the required pump rotation speed so that it becomes smaller, and the pump current and pump rotation speed when the relief valve opens by gradually increasing the required pump rotation speed until the relief valve opens. An execution device that executes a learning process for learning the above and an update process for correcting the estimation mapping data based on the result of the learning process.
A control device for a fuel supply system. A plurality of the estimation mapping data having different fuel temperature levels corresponding to the storage device are stored in the storage device.
In the feed pressure estimation process, the execution device derives a mapping corresponding to the fuel temperature by interpolation from the two estimation mapping data, and inputs the pump rotation speed and the pump current to the derived mapping to feed the map. The control device for a fuel supply system according to claim 1, wherein an estimated value of pressure is calculated. In the update process, the execution device corrects the map derived by interpolation so that a value equal to the valve opening pressure is output when the pump rotation speed and the pump current acquired through the learning process are input. The control device for a fuel supply system according to claim 2, wherein the correction content of the map derived by interpolation is reflected in a plurality of the estimation map data stored in the storage device. The control device for a fuel supply system according to any one of claims 1 to 3, wherein the execution device executes the learning process when fuel injection is not performed. Any of claims 1 to 4, wherein the executing device executes a determination process of determining that an abnormality has occurred when the correction amount of the estimation mapping data by the update process deviates from the permissible range. The control device for the fuel supply system according to paragraph 1. The control device for a fuel supply system according to claim 5, wherein the executing device moves the permissible range in the determination process to the side where the correction amount increases as the integrated operating amount of the feed pump increases. In the determination process, the execution device determines that an abnormality has occurred when the correction amount of the estimation mapping data by the update process deviates from the permissible range and is not immediately after refueling. The method according to claim 5 or 6, wherein when the correction amount of the estimation mapping data by the update process deviates from the permissible range and immediately after refueling, it is determined that the type of fuel in the fuel tank has been switched. Fuel supply system controller. The storage device stores a plurality of rotation speed calculation mapping data having different types of corresponding fuels, which output the required pump rotation speed by inputting the required feed pressure and the fuel injection amount.
In the required pump rotation speed calculation process, the execution device calculates the required pump rotation speed using the mapping data for calculating the rotation speed.
The fuel supply system according to claim 7, wherein when it is determined in the determination process that the type of fuel has been switched, the execution device switches the mapping data for rotation speed calculation used in the required pump rotation speed calculation process. Control device.

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