WO2017064945A1

WO2017064945A1 - Vehicle fuel injection device and control device

Info

Publication number: WO2017064945A1
Application number: PCT/JP2016/076241
Authority: WO
Inventors: 将巳中村; 智行高川
Original assignee: 株式会社デンソー
Priority date: 2015-10-16
Filing date: 2016-09-07
Publication date: 2017-04-20
Also published as: JP2017075580A

Abstract

A fuel injection device (10) having: a low-pressure pump (12) that discharges fuel from a fuel tank (11); a low-pressure delivery pipe (14) that supplies the fuel discharged from the low-pressure pump (12) to port injectors (15) that inject fuel into intake ports (4) of an engine (1); a high-pressure pump (16) that pressurizes and discharges the fuel discharged from the low-pressure pump (12); a high-pressure delivery pipe (18) that supplies the fuel discharged from the high-pressure pump (16) to cylinder injectors (19) that inject fuel into cylinders (5) of the engine (1); and a discharge pipe (20) that is connected between the high-pressure delivery pipe (18) and the low-pressure delivery pipe (14) of the low-pressure fuel system from the fuel tank (11) to the intake ports (4), and is configured so as to be capable of discharging fuel in the high-pressure delivery pipe (18) to the low-pressure fuel system and of increasing the discharge amount of the high-pressure pump (16).

Description

Vehicle fuel injection device and control device

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2015-204265 filed on October 16, 2015, and the contents thereof are disclosed in this specification.

The present disclosure relates to a vehicle fuel injection device and a control device that controls the operation of the fuel injection device.

2. Description of the Related Art Recently, a fuel injection device is known that includes both an in-cylinder injector that injects fuel into a cylinder of an engine and a port injector that injects fuel into an intake port. This fuel injection device controls the in-cylinder injector (also referred to as “in-cylinder injector”) and the port injector (also referred to as “intake passage injector”) according to the operating state, The fuel can be injected by combining the internal fuel injection and the internal port fuel injection.

In such a fuel injection device, depending on the operating state of the internal combustion engine, the fuel injection ratio by the intake manifold injector may increase, and the fuel injection ratio by the in-cylinder injector may decrease accordingly. For this reason, the amount of fuel flowing through the high-pressure fuel system decreases or the flow rate becomes completely zero.

In the high-pressure fuel system, the high-pressure fuel pump increases the pressure of the low-pressure fuel. Since this high-pressure fuel pump is attached to the cylinder head, the amount of heat received from the internal combustion engine tends to be large.

For this reason, when the fuel injection ratio by the intake manifold injector increases, the fuel flow rate in the high-pressure fuel system decreases, so the amount of heat taken away by the heat capacity of the flowing fuel becomes very small or not at all. . This may cause the high pressure fuel system to become hot.

When the internal fuel temperature becomes extremely high due to this high temperature, and the saturated vapor pressure of the fuel becomes higher than the pressure in the high-pressure fuel system, the generation of vapor in the high-pressure fuel system is promoted, and the fuel injection amount by the in-cylinder injector May adversely affect the operation stability of the internal combustion engine. In order to prevent such a phenomenon, it is effective to suppress the vaporization of the fuel on the fuel supply path, that is, to suppress the high temperature of the fuel. For example, in Patent Document 1, a high-pressure pump that pressurizes fuel to be supplied to an in-cylinder injector includes a detour that can supply fuel supplied to the high-pressure pump to the port injector when the in-cylinder injector is stopped. Is disclosed. With this configuration, it is possible to prevent the fuel from staying in the high-pressure pump even when the in-cylinder fuel injection is not performed. Therefore, the fuel can be made difficult to receive heat from the engine, and the temperature of the fuel can be suppressed.

US Patent Application Publication No. 2012/0279474

However, since the fuel injection device described in Patent Document 1 needs to provide a detour in the high-pressure pump in order to suppress the high temperature of the fuel, a pump having a special structure is necessary and lacks versatility. There is a demand for a fuel injection device that can suppress the high temperature of the fuel with a simpler configuration.

The present disclosure has been made in view of such problems, and an object of the present disclosure is to provide a fuel injection device for a vehicle that can suitably suppress an increase in fuel temperature and a control device that controls the operation of the fuel injection device. There is to do.

In order to solve the above problems, in the present disclosure, a fuel tank that stores fuel, a low-pressure pump that discharges fuel in the fuel tank, and a port that injects fuel into an intake port of an engine mounted on a vehicle A low-pressure delivery pipe that has an injection unit and supplies fuel discharged from the low-pressure pump to the port injection unit; a high-pressure pump that pressurizes and discharges fuel discharged from the low-pressure pump; and a cylinder of the engine A high-pressure delivery pipe for supplying fuel discharged from the high-pressure pump to the in-cylinder injection section; and from the fuel tank to the intake port via the low-pressure delivery pipe Is connected between the low pressure fuel system and the high pressure delivery pipe, and the fuel inside the high pressure delivery pipe can be discharged to the low pressure fuel system, Provides a fuel injection device and a discharge pipe configured to allow increasing the discharge amount of the high-pressure pump.

Similarly, in order to solve the above problems, in the present disclosure, fuel is stored in a fuel tank that stores fuel, a low-pressure pump that discharges fuel in the fuel tank, and an intake port of an engine mounted on the vehicle. A low-pressure delivery pipe having a port injection unit for injecting, and supplying fuel discharged from the low-pressure pump to the port injection unit; a high-pressure pump for pressurizing and discharging fuel discharged from the low-pressure pump; and the engine A cylinder injection section for injecting fuel into the cylinder, a high pressure delivery pipe for supplying the fuel discharged from the high pressure pump to the cylinder injection section, and the fuel tank through the low pressure delivery pipe Connected between the low-pressure fuel system up to the intake port and the high-pressure delivery pipe, the fuel inside the high-pressure delivery pipe can be discharged to the low-pressure fuel system. And a discharge pipe configured to be capable of increasing the discharge amount of the high-pressure pump, and a flow rate adjusting unit that is provided in the discharge pipe and adjusts the flow rate of the fuel flowing through the discharge pipe. A controller for controlling the operation of the apparatus, wherein the controller acquires information relating to a fuel temperature in the high-pressure pump, and controls the operation of the flow rate adjusting unit to increase the flow rate when the fuel temperature is higher than a predetermined value. A control device is provided.

This configuration enables the fuel to be discharged from the high pressure delivery pipe to the low pressure fuel system, and the discharge of fuel inside the high pressure delivery pipe is promoted. By increasing the amount of fuel discharged from the high-pressure delivery pipe, it becomes easier to discharge the fuel from the high-pressure pump to the high-pressure delivery pipe, and the discharge amount of the high-pressure pump can be increased. By increasing the discharge amount of the high-pressure pump, it is possible to reduce the fuel staying inside the high-pressure pump, which is easy to receive heat from the engine side. As a result, the high temperature of the fuel is suitably suppressed.

According to the present disclosure, it is possible to provide a fuel injection device and a control device for a vehicle that can suitably suppress a high temperature of fuel.

FIG. 1 is a diagram illustrating a schematic configuration of a fuel injection device for a vehicle according to a first embodiment of the present disclosure. FIG. 2 is a flowchart showing each process of fuel release control performed by the fuel injection device shown in FIG. FIG. 3 is a flowchart showing each process of the fuel pressure reduction control performed by the fuel injection device shown in FIG. FIG. 4 is a diagram for explaining the effect of the fuel pressure reduction control. FIG. 5 is a diagram showing a schematic configuration of a modified example of the first embodiment. FIG. 6 is a diagram illustrating a schematic configuration of a fuel injection device for a vehicle according to a second embodiment of the present disclosure. FIG. 7 is a flowchart showing each process of the fuel release control performed by the fuel injection device shown in FIG. FIG. 8 is a flowchart showing each process of the fuel pressure reduction control performed by the fuel injection device shown in FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

[First Embodiment]
The first embodiment will be described with reference to FIGS. First, the configuration of the fuel injection device for a vehicle according to the first embodiment of the present disclosure will be described with reference to FIG. In the following description, the “vehicle fuel injection device” according to the present embodiment is simply referred to as “fuel injection device 10”.

As shown in FIG. 1, the fuel injection device 10 is a device for supplying fuel to the engine 1 mounted on the vehicle. Although an in-line four-cylinder gasoline engine is illustrated as the engine 1 in FIG. 1, the fuel injection device 10 of the present embodiment can be applied to other engines.

As shown in FIG. 1, the engine 1 includes four cylinders 5, and each cylinder 5 is connected to a common surge tank 3 through a corresponding intake port 4. That is, the engine 1 includes four intake ports 4, and each intake port 4 is connected to communicate between one of the four cylinders 5 and the surge tank 3. An intake duct 2 is connected to the surge tank 3, and a throttle valve 6 is disposed inside the intake duct 2.

For each cylinder 5, an in-cylinder injector 19 (in-cylinder injection unit) for injecting fuel into the cylinder, and a port injector 15 for injecting fuel into the intake port 4. (Port injection unit) are provided. The fuel injection control by the in-cylinder injector 19 and the port injector 15, the ignition control of the engine 1, and the throttle opening control by the throttle valve 6 are performed by an engine ECU (Electronic Control Unit) based on various information of the vehicle.

Each of the port injectors 15 is connected to a low pressure delivery pipe 14. The low pressure delivery pipe 14 is a fuel distribution pipe shared by the injectors 15, and supplies fuel discharged from the low pressure pump 12 provided in the fuel tank 11 to each of the port injectors 15. The inlet of the low pressure delivery pipe 14 is connected to the low pressure side pipe 13 b of the supply pipe 13.

The supply pipe 13 supplies the fuel discharged from the low pressure pump 12 to the low pressure delivery pipe 14 and a high pressure pump 16 described later. The supply pipe 13 has a branch portion 13a that branches a pipeline from a single inlet into a low-pressure side pipe 13b and a high-pressure side pipe 13c that go to two outlets. The inlet of the supply pipe 13 is connected to the outlet of the low pressure pump 12. The outlet of the low pressure side pipe 13 b is connected to the inlet of the low pressure delivery pipe 14. The outlet of the high pressure side pipe 13 c is connected to the inlet of the high pressure pump 16. The supply pipe 13 can branch and supply the fuel discharged from the low-pressure pump 12 to the low-pressure delivery pipe 14 and the high-pressure pump 16 by the branch portion 13a.

The fuel tank 11 is provided with a low pressure pump 12. The low pressure pump 12 sucks the fuel stored in the fuel tank 11, pressurizes it with a relatively low pressure (for example, about 0.3 MPa), and then discharges it to the supply pipe 13.

Each of the in-cylinder injectors 19 is connected to a high-pressure delivery pipe 18. The high-pressure delivery pipe 18 is a fuel distribution pipe shared by the injectors 19 and supplies the fuel supplied from the fuel tank 11 to each of the in-cylinder injectors 19. The inlet of the high pressure delivery pipe 18 is connected to the outlet of the high pressure delivery pipe 17. The high pressure delivery pipe 17 is connected to the outlet of the high pressure pump 16.

The high-pressure pump 16 is provided between the high-pressure side pipe 13c of the supply pipe 13 and the high-pressure delivery pipe 17, and pressurizes the fuel introduced from the high-pressure side pipe 13c at a relatively high pressure (for example, about 3.0 MPa). From the high pressure delivery pipe 17 to the high pressure delivery pipe 18. In other words, the high pressure pump 16 pressurizes and discharges the fuel discharged from the low pressure pump 12, and the high pressure delivery pipe 18 supplies the fuel discharged from the high pressure pump 16 to each of the in-cylinder injectors 19. .

The drive control of the low pressure pump 12 is performed by the engine ECU. The high-pressure pump 16 is directly connected to the crankshaft of the engine 1 and is driven according to the operation of the engine 1. The high-pressure pump 16 does not discharge fuel to the high-pressure delivery pipe 18 in a situation where fuel is not supplied by the in-cylinder injector 19 in the high-pressure delivery pipe 18 by providing a check valve or the like at the discharge port, for example. It is configured as follows.

In the present embodiment, a configuration in which low-pressure fuel is supplied from the fuel tank 11 to the intake port 4 via the low-pressure pump 12, the low-pressure delivery pipe 14, and the port injector 15 is referred to as “low-pressure fuel system”. A configuration in which high-pressure fuel is supplied to each cylinder 5 through the high-pressure pump 16, the high-pressure delivery pipe 18, and the in-cylinder injector 19 is referred to as “high-pressure fuel system”.

The fuel injection device 10 according to this embodiment includes the fuel tank 11, the low pressure pump 12, the supply pipe 13, the low pressure delivery pipe 14, the port injector 15, the high pressure pump 16, the high pressure delivery pipe 18, and the in-cylinder injector. 19 is provided. Furthermore, the fuel injection device 10 includes a discharge pipe 20, a solenoid valve 21 (flow rate adjustment unit), a temperature sensor 22, a pressure sensor 23, and a control unit 24.

The discharge pipe 20 is connected to the low pressure delivery pipe 14 so that fuel can be discharged from the high pressure delivery pipe 18. The outlet of the discharge pipe 20 is connected to the high pressure delivery pipe 18 and the outlet is connected to the low pressure delivery pipe 14.

The solenoid valve 21 is provided inside the discharge pipe 20. The electromagnetic valve 21 can adjust the flow rate of the fuel flowing through the discharge pipe 20 according to its opening. The opening degree of the electromagnetic valve 21 is controlled in accordance with a control command from the control unit 24.

The temperature sensor 22 is provided at the inlet of the high-pressure pump 16 and measures the temperature of the fuel that stays in or flows through the high-pressure pump 16. The pressure sensor 23 is provided in the high pressure delivery pipe 18 and measures the fuel pressure inside the high pressure delivery pipe. Information measured by the temperature sensor 22 and the pressure sensor 23 is output to the control unit 24.

The control unit 24 controls the operation of the electromagnetic valve 21. More specifically, the control unit 24 opens the electromagnetic valve 21 when the fuel temperature is higher than a predetermined value based on the fuel temperature in the high-pressure pump 16 measured by the temperature sensor 22, thereby providing a high-pressure delivery. Control is performed to increase the flow rate of fuel discharged from the pipe 18 via the discharge pipe 20. Hereinafter, this control is referred to as “fuel release control”, and the discharge pipe 20 and the electromagnetic valve 21 that are elements related to the fuel release control in the fuel injection device 10 are referred to as “relief mechanism”.

The control unit 24 is physically configured as a computer system including a CPU (controller) 24a, a ROM, a RAM, and an input / output interface (not shown). The control unit 24 is mounted as a part of an engine ECU of a vehicle on which the fuel injection device 10 is mounted, for example. The control unit 24 is a component of the fuel injection device 10 as described above, and can also be expressed as a “control device” that controls the operation of the fuel injection device 10 by controlling the electromagnetic valve 21.

Details of the fuel release control in the first embodiment will be described with reference to FIG. The flowchart shown in FIG. 2 is repeatedly performed by the control unit 24 at predetermined intervals, for example.

In step S101, the fuel temperature (actual fuel temperature) in the high-pressure pump 16 is detected based on the information measured by the temperature sensor 22. This actual fuel temperature is typically the situation where fuel injection by the in-cylinder injector 19 provided in the high-pressure delivery pipe 18 is not executed, and the electromagnetic valve 21 is closed and fuel is discharged from the discharge pipe 20. This is the temperature of the fuel that is not discharged into the high-pressure delivery pipe 18 and stays in the vicinity of the inlet of the high-pressure pump 16 in a state where it is not discharged. The actual fuel temperature is estimated by the control unit 24 based on various vehicle information (for example, engine water temperature, outside air temperature, etc.) in addition to the configuration directly measured by the temperature sensor 22 as shown in FIG. It may be a configuration. When the process of step S101 is completed, the process proceeds to step S102.

In step S102, it is determined whether the actual fuel temperature detected in step S101 is equal to or higher than a predetermined upper limit fuel temperature (actual fuel temperature ≧ upper limit fuel temperature). As a result of the determination in step S102, when the actual fuel temperature is equal to or higher than the predetermined upper limit fuel temperature (Yes in step S102), the process proceeds to step S103. Otherwise (No in step S102), the process proceeds to step S105.

In step S103, it is determined whether or not fuel injection by the port injector 15 is being executed in the low pressure delivery pipe 14. As a result of the determination in step S103, if fuel injection is being performed in the low pressure delivery pipe 14 (Yes in step S103), the process proceeds to step S105, and if fuel injection is not being performed (No in step S103). Proceed to step S104.

The process proceeds to step S104 when, as a result of the determination in steps S102 and S103, the actual fuel temperature is equal to or higher than a predetermined upper limit fuel temperature, and fuel injection is not being performed in the low pressure delivery pipe 14. At this time, since the fuel temperature inside the high-pressure pump 16 is in a high temperature state and may be vaporized, it is necessary to perform fuel release control to prevent this. Further, “the state in which fuel injection is not being executed in the low-pressure delivery pipe 14” is a feasible condition for the fuel release control in the present embodiment. Therefore, in step S104, the feasible condition is satisfied, so the solenoid valve 21 is opened and the fuel release control is performed. As a result, the fuel inside the high pressure delivery pipe 18 is discharged to the low pressure delivery pipe 14 via the discharge pipe 20. When the process of step S104 is completed, the process proceeds to step S106.

In step S105, the actual fuel temperature is lower than the predetermined upper limit fuel temperature as a result of the determination in step S102, and it is not necessary to perform the fuel release control, or in the low pressure delivery pipe 14 as a result of the determination in step S103. Since the fuel injection is being executed and does not satisfy the requirements for enabling the fuel release control, the solenoid valve 21 is closed and the fuel release control is stopped. When the process of step S105 is completed, this control flow ends.

In step S106, it is determined whether or not the temperature (fuel temperature) of the fuel in the high-pressure pump 16 has decreased due to the fuel release control in step S104. The control unit 24 can acquire the fuel temperature information by the same method as in step S101, for example. If the result of determination in step S106 is that the fuel temperature has decreased (Yes in step S106), the relief mechanism (discharge pipe 20, electromagnetic valve 21) is diagnosed as normal in step S107, and The process ends. On the other hand, if the fuel temperature is not lowered despite the fuel release control (No in step S106), some abnormality has occurred in the relief mechanism in step S108, and the fuel is properly discharged. It is diagnosed that it is not, and the processing of this control flow is terminated. By the processing of steps S106 to S108, the abnormality diagnosis of the relief mechanism can be performed simultaneously with the fuel release control, and when the abnormality occurs, it can be promptly notified to the vehicle driver and the maintenance staff.

The fuel injection device 10 according to the present embodiment includes a direct injection control that directly injects fuel into the cylinder 5 using the in-cylinder injector 19 and a port injection that injects fuel into the intake port 4 using the port injector 15. A configuration is used in which two types of fuel injection methods are used together with control. When the direct injection control is stopped and only the port injection control is performed, the high pressure pump 16 is driven as the engine 1 is driven, but the fuel in the high pressure delivery pipe 18 is not discharged. The fuel introduced into the high-pressure pump 16 stays in the vicinity of the inlet without being discharged. Similarly, even when the port injection control and the direct injection control are used together and the frequency of the direct injection control is low, the fuel tends to stay in the high pressure pump 16. When the fuel stays in the high-pressure pump 16 in this way, the staying fuel easily receives a heat from the engine 1 side and rises in temperature. Therefore, the fuel may partially vaporize. When the fuel in the high-pressure pump 16 is vaporized, sufficient fuel cannot be discharged from the high-pressure pump 16 to the high-pressure delivery pipe 18 side. As a result, the fuel injection amount by the in-cylinder injector 19 becomes insufficient in the high-pressure fuel system. There is a risk of adversely affecting the operational stability of the engine 1.

For such a problem, the fuel injection device 10 of the present embodiment includes a discharge pipe 20 connected between the high-pressure delivery pipe 18 and the low-pressure delivery pipe 14. The discharge pipe 20 enables the fuel to be discharged from the high pressure delivery pipe 18 to the low pressure delivery pipe 14, and the discharge of the fuel inside the high pressure delivery pipe 18 is promoted. By increasing the amount of fuel discharged from the high-pressure delivery pipe 18, it becomes easier to discharge the fuel from the high-pressure pump 16 to the high-pressure delivery pipe 18, and the discharge amount of the high-pressure pump 16 can be increased. By increasing the discharge amount of the high-pressure pump 16, it is possible to reduce the fuel staying inside the high-pressure pump 16, which is easy to receive heat from the engine 1 side. In addition, by setting the fuel discharge destination to the low pressure delivery pipe 14 on the downstream side of the branching portion 13a, it is possible to avoid the discharged high temperature fuel from being introduced into the high pressure pump 16 again. As a result, the fuel injection device 10 of the present embodiment can favorably suppress the high temperature of the fuel. Further, by suppressing the increase in the temperature of the fuel, it is possible to suppress the vaporization of the fuel, and it is possible to suitably prevent the problem that the fuel injection amount becomes insufficient in the high-pressure fuel system. Moreover, since the discharge amount of the high-pressure pump 16 can be increased even if an existing general-purpose product is diverted to the high-pressure pump 16, it is possible to suppress an increase in fuel temperature with a simple configuration.

Further, the fuel injection device 10 of the present embodiment includes an electromagnetic valve 21 that is provided in the discharge pipe 20 and adjusts the flow rate of the fuel flowing through the discharge pipe 20, and a control unit 24 that controls the operation of the electromagnetic valve 21. As shown in steps S102 and S104 of FIG. 2, the control unit 24 opens the electromagnetic valve 21 when the fuel temperature in the high-pressure pump 16 is higher than a predetermined upper limit fuel temperature, thereby allowing the fuel flowing through the discharge pipe 20 to flow. Implement fuel release control to increase the flow rate. As a result, in a situation where the fuel temperature in the high-pressure pump 16 becomes high and vapor is likely to be generated in the high-pressure fuel system, the discharge amount of the high-pressure pump 16 is increased and the fuel staying inside the high-pressure pump 16 is increased. Since it can reduce, the high temperature of a fuel can be suppressed at an appropriate timing. Further, since the fuel discharge amount can be continuously controlled by adjusting the opening degree of the electromagnetic valve 21, for example, the discharge amount is increased or decreased according to the degree of deviation of the fuel temperature from the upper limit fuel temperature, and the rate of decrease in the fuel temperature. The fuel release control can be performed with high accuracy, for example, by increasing / decreasing the fuel consumption rate or by increasing the emission amount when the fuel temperature lowers slowly. Thereby, the fuel temperature can be maintained at a predetermined temperature, and the fuel injection amount can be stabilized. On the other hand, as shown in steps S102 and S105 of FIG. 2, when the fuel temperature in the high-pressure pump 16 is equal to or lower than a predetermined upper limit fuel temperature, the fuel release control is not performed and the electromagnetic valve 21 is closed and the high-pressure delivery pipe 18 Since there is no fuel discharge, it is possible to suppress the flow of useless fuel by reducing the discharge amount of the high-pressure pump 16 in a situation where vapor is generated in the high-pressure fuel system and the fuel injection amount is unlikely to be insufficient. .

Further, in the fuel injection device 10 of the present embodiment, the controller 24 is used for the port of the low pressure delivery pipe 14 when the fuel temperature is higher than a predetermined upper limit fuel temperature, as shown in steps S103 to S105 in FIG. When the injector 15 is stopped, the fuel release control is performed to control the solenoid valve 21 so that the fuel flows through the discharge pipe 20. When fuel is discharged from the high-pressure delivery pipe 18 to the low-pressure delivery pipe 14 via the discharge pipe 20, high-pressure fuel is introduced, so that pulsation occurs in the fuel pressure inside the low-pressure delivery pipe 14. At this time, if the port injection control using the port injector 15 is performed in the low pressure delivery pipe 14, the fuel injection amount fluctuates due to the influence of the fuel pressure pulsation, which may deteriorate the accuracy of the injection control. In the present embodiment, “the fuel injection using the port injector 15 is not executed in the low pressure delivery pipe 14” is set as a feasible condition for the fuel release control, so that the low pressure delivery is performed while the port injector 15 is in operation. It is possible to prevent the fuel from being discharged into the pipe 14, and thus it is possible to suitably suppress the increase in the temperature of the fuel by the fuel release control while reducing the influence of the fuel pressure pulsation on the port injection.

Further, the control unit 24 can perform another control using the elements (the discharge pipe 20 and the electromagnetic valve 21) of the fuel injection device 10 related to the fuel release control. Specifically, based on the fuel pressure inside the high-pressure delivery pipe 18 measured by the pressure sensor 23, the control unit 24 opens the solenoid valve 21 when the fuel pressure is higher than the target fuel pressure by a predetermined amount. Then, the exhaust pipe 20 is connected to perform control to reduce the fuel pressure of the high-pressure delivery pipe 18. Hereinafter, this control is referred to as “fuel pressure reduction control”.

Details of the fuel pressure reduction control in the first embodiment will be described with reference to FIG. The flowchart shown in FIG. 3 is repeatedly performed by the control unit 24 at predetermined intervals, for example.

In step S201, the fuel pressure (actual fuel pressure) in the high-pressure delivery pipe 18 is detected based on the information measured by the pressure sensor 23. The actual fuel pressure may be a configuration estimated by the control unit 24 based on various types of vehicle information in addition to the configuration directly measured by the pressure sensor 23 as shown in FIG. When the process of step S201 is completed, the process proceeds to step S202.

In step S202, it is determined whether or not the actual fuel pressure detected in step S201 is higher than a predetermined target fuel pressure by a predetermined value or more. As a result of the determination in step S202, when the actual fuel pressure is higher than the target fuel pressure by a predetermined value or more (Yes in step S202), the process proceeds to step S203. Otherwise (No in step S202), the process proceeds to step S205.

In step S203, it is determined whether or not fuel injection by the port injector 15 is being executed in the low pressure delivery pipe 14. As a result of the determination in step S203, if fuel injection is being performed in the low pressure delivery pipe 14 (Yes in step S203), the process proceeds to step S205, and if fuel injection is not being performed (No in step S203). Proceed to step S204.

The process proceeds to step S204 when the actual fuel pressure is higher than the target fuel pressure by a predetermined value or more and fuel injection is not being performed in the low-pressure delivery pipe 14 as a result of the determination in steps S202 and S203. At this time, since the difference between the fuel pressure inside the high-pressure delivery pipe 18 and the target fuel pressure is large, it is necessary to perform fuel pressure reduction control to eliminate this. Further, “the state in which fuel injection is not being executed in the low pressure delivery pipe 14” is a feasible condition for the fuel pressure reduction control in the present embodiment. Therefore, in step S204, since the feasible condition is satisfied, the solenoid valve 21 is opened and the fuel pressure reduction control is performed. As a result, the fuel pressure inside the high-pressure delivery pipe 18 is extracted from the discharge pipe 20 to the low-pressure delivery pipe 14. When the process of step S204 is completed, the process proceeds to step S206.

In step S205, as a result of the determination in step S202, the difference between the actual fuel pressure and the target fuel pressure is less than a predetermined value, and it is not necessary to perform the fuel pressure reduction control. Alternatively, as a result of the determination in step S203, the low-pressure delivery pipe 14 Since the fuel injection is being performed in step S3 and the fuel pressure reduction control enablement requirement is not satisfied, the solenoid valve 21 is closed and the fuel pressure reduction control is stopped. When the process of step S205 is completed, the control flow ends.

In step S206, it is determined whether or not the fuel pressure (fuel pressure) in the high-pressure delivery pipe 18 is reduced by performing the fuel release control in step S204. For example, the control unit 24 can acquire fuel pressure information by the same method as in step S201. If the result of determination in step S206 is that the fuel pressure has decreased (Yes in step S206), the relief mechanism (discharge pipe 20, electromagnetic valve 21) is diagnosed as normal in step S207, and the processing of this control flow is performed. Exit. On the other hand, if the fuel pressure is not reduced despite the fuel pressure reduction control (No in step S206), some abnormality has occurred in the relief mechanism in step S208, and the fuel pressure is appropriately reduced. It is diagnosed that it is not, and the processing of this control flow is terminated. By the processing in steps S206 to S208, the abnormality diagnosis of the relief mechanism can be performed simultaneously with the fuel pressure reduction control, and when the abnormality occurs, it can be promptly notified to the driver of the vehicle and the maintenance staff.

The effect of fuel pressure reduction control will be described with reference to FIG. The vertical axis in FIG. 4 represents the fuel pressure of the high-pressure delivery pipe 18, and the horizontal axis represents time. Moreover, the graph A shown in FIG. 4 shows the time transition of the target fuel pressure. Graph B shows a time transition of the fuel pressure when the fuel pressure reduction control is performed using the relief mechanism (discharge pipe 20, electromagnetic valve 21) of the present embodiment. Graph C shows a time transition of the fuel pressure by a configuration that does not have a relief mechanism as a comparative example and does not perform fuel pressure reduction control.

Suppose that the target fuel pressure is reduced stepwise as shown in graph A of FIG. Such a situation includes, for example, when a fuel cut occurs or when a state change occurs during transient operation. In accordance with such a variation in the target fuel pressure, in the configuration of the comparative example as shown in the graph C, the fuel pressure may not decrease sufficiently or the fuel pressure may decrease slowly. At this time, in the fuel pressure reduction control of the present embodiment, the fuel pressure can be released from the high pressure delivery pipe 18 through the discharge pipe 20, so that the fuel pressure can be quickly lowered to the target fuel pressure as shown in graph B, and the fuel pressure follows. Can be improved.

Further, as shown in steps S203 to S205 of FIG. 3, by making the fuel pressure reduction control feasible condition that "the fuel injection using the port injector 15 is not executed in the low pressure delivery pipe 14", It is possible to prevent high-pressure fuel from being discharged to the low-pressure delivery pipe 14 while the port injector 15 is in operation, thereby reducing the influence of fuel pressure pulsation on the port injection and fuel pressure tracking by fuel pressure reduction control. Can be improved.

[Modification of First Embodiment]
A modification of the first embodiment will be described with reference to FIG. In the first embodiment, a fuel that is discharged from the high-pressure delivery pipe to the low-pressure delivery pipe through the discharge pipe 20 by providing an electromagnetic valve 21 on the flow path inside the discharge pipe 20 and controlling the opening and closing of the electromagnetic valve 21. However, the electromagnetic valve 21 can be replaced with another element. For example, as shown in FIG. 5, in the fuel injection device 10 </ b> A, a leak mechanism 30 can be provided on the flow path of the discharge pipe 20 instead of the electromagnetic valve 21.

The leak mechanism 30 is a hole provided so as to reduce the inner diameter of the discharge pipe 20. The leak mechanism 30 can circulate fuel between the high-pressure delivery pipe 18 and the low-pressure delivery pipe 14 with a certain flow resistance. The discharge pipe 20 is configured so that the high-pressure delivery pipe 18 and the low-pressure delivery pipe 14 are always communicated with each other by providing the leak mechanism 30 in the flow path, and the inner diameter is communicated without providing the leak mechanism 30. As compared with, the flow rate of the fuel discharged from the high-pressure delivery pipe 18 can be suppressed. Thus, in the fuel injection device 10A, fuel discharge from the high pressure delivery pipe 18 can be promoted to increase the discharge amount of the high pressure pump 16, and the fuel pressure in the high pressure delivery pipe 18 can be maintained well. Therefore, the fuel injection device 10 </ b> A can also achieve the same effects as the fuel injection device 10, that is, suppression of the high temperature of the fuel and improvement in fuel pressure followability.

Also, the solenoid valve 21 can be replaced with another element that can adjust the flow rate of the discharge pipe 20.

[Second Embodiment]
The second embodiment will be described with reference to FIGS. As shown in FIG. 6, the fuel injection device 110 according to the second embodiment is different from that of the first embodiment in that one end of the discharge pipe 120 is connected to one of the intake ports 4 instead of the low pressure delivery pipe 14. Different from the fuel injection device 10. In the fuel injection device 110 of the second embodiment, when the electromagnetic valve 21 is opened during the fuel release control, the fuel discharged from the high-pressure delivery pipe 18 is supplied to the relief mechanism (the discharge pipe 120, the electromagnetic valve 21). It is discharged into the connected intake port 4 and mixed with air introduced from the intake duct 2 to be introduced into each cylinder 5 as an air-fuel mixture. Further, when the fuel pressure reduction control is performed, the fuel pressure is released from the high pressure delivery pipe 18 to the intake port 4.

Details of the fuel release control in the second embodiment will be described with reference to FIG. The flowchart shown in FIG. 7 is basically the same procedure as the flowchart of the fuel release control in the first embodiment shown in FIG. Each process of steps S301, S302, and S307 to S309 is the same as steps S101, S102, and S106 to S108 in the flowchart of FIG. A series of processes in the flowchart shown in FIG. 7 is repeatedly performed by the control unit 124 at predetermined intervals, for example. As in the first embodiment, the control unit 124 is configured as a computer system including a CPU (controller) 124a, a ROM, a RAM, and an input / output interface (not shown).

If the result of determination in step S302 is that the actual fuel temperature is equal to or higher than a predetermined upper limit fuel temperature, fuel release control shown in steps S303 to S304 below is performed. First, in step S303, fuel injection by the port injector 15 of the intake port 4 to which the relief mechanism is connected is stopped. Next, in step S304, the fuel injection amount control of the intake port 4 is performed using the solenoid valve 21 of the relief mechanism. That is, when the fuel release control is performed, the control unit 124 stops the port injector 15 of the intake port 4 to which the exhaust pipe 120 is connected and is supplied from the exhaust pipe 120 to the intake port 4 by the electromagnetic valve 21. Control the amount of fuel. In other words, when performing the fuel release control, the control unit 124 performs air-fuel ratio control (lambda control) using the electromagnetic valve 21 instead of the port injector 15 in the intake port 4 to which the relief mechanism is connected. As a result, the fuel inside the high-pressure delivery pipe 18 can be discharged from the discharge pipe 120 to the intake port 4 and the amount of fuel flowing into the cylinder 5 to which the intake port 4 is connected can also be controlled. When the process of step S304 is completed, the process proceeds to step S307.

On the other hand, if the result of determination in step S302 is that the actual fuel temperature is less than the predetermined upper limit fuel temperature, the fuel release control is stopped as shown in steps S305 to S306 below. First, in step S305, the electromagnetic valve 21 is closed and the fuel injection amount control to the intake port 4 by the electromagnetic valve 21 is stopped. Next, in step S306, fuel injection is performed by the port injector 15 of the intake port 4 to which the relief mechanism is connected. In other words, when the fuel release control is not performed, the control unit 124 performs air-fuel ratio control using the port injector 15 as usual in the intake port 4 to which the relief mechanism is connected. When the process of step S306 is completed, the control flow ends.

In the fuel release control, air-fuel ratio control of the intake port 4 may be performed by using the port injector 15 and the electromagnetic valve 21 in combination instead of steps S303 to S304. Specifically, the control unit 124 controls the solenoid valve 21 so that the fuel injection amount by the port injector 15 is reduced and the fuel flows through the discharge pipe 120. Further, the control unit 124 controls the amount of fuel supplied to the intake port 4 by the electromagnetic valve 21 or the port injector 15.

Details of the fuel pressure reduction control in the second embodiment will be described with reference to FIG. The flowchart shown in FIG. 8 is basically the same procedure as the flowchart of the fuel pressure reduction control in the first embodiment shown in FIG. Each process of steps S401, S402, and S407 to S409 is the same as steps S201, S202, and S206 to S208 in the flowchart of FIG.

If the result of determination in step S402 is that the actual fuel pressure is higher than the target fuel pressure by a predetermined value or more, fuel pressure reduction control shown in steps S403 to S404 is performed. The processes in steps S403 to S404 are the same as those in steps S303 to S304 in FIG. Instead, air-fuel ratio control is performed using the electromagnetic valve 21. As a result, the fuel pressure inside the high-pressure delivery pipe 18 can be extracted from the discharge pipe 20 to the intake port 4, and the amount of fuel flowing into the cylinder 5 to which the intake port 4 is connected can also be controlled. When the process of step S404 is completed, the process proceeds to step S407.

On the other hand, if the result of determination in step S402 is that the difference between the actual fuel pressure and the target fuel pressure is less than a predetermined value, the fuel pressure reduction control is stopped as shown in steps S405 to S406. The processes in steps S405 to S406 are the same as those in steps S305 to S306 in FIG. 7. When the fuel pressure reduction control is not performed, the control unit 124 performs the port injector as usual in the intake port 4 to which the relief mechanism is connected. 15 is used to perform air-fuel ratio control. When the process of step S406 is completed, the control flow ends.

The fuel injection device 110 according to the second embodiment is provided with a relief mechanism (the discharge pipe 120 and the electromagnetic valve 21), thereby suppressing the increase in fuel temperature and improving the fuel pressure followability according to the first embodiment. The same effect as the device 10 can be obtained.

The embodiments of the present disclosure have been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. That is, those specific examples modified by appropriate design by those skilled in the art are also included in the scope of the present disclosure as long as they have the features of the present disclosure. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, and can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present disclosure as long as it includes the features of the present disclosure.

In the above embodiment, the

exhaust pipes

20 and 120 for discharging the fuel from the high-pressure delivery pipe 18 are illustrated as being connected to the low-pressure delivery pipe 14, the fuel tank 11, or the intake port 4 as outlets. The outlet may be connected to an element other than the above. The

discharge pipes

20 and 120 only need to be connected between the low pressure fuel system from the fuel tank 11 through the low pressure delivery pipe 14 to the intake port 4 and the high pressure delivery pipe 18. Further, the

discharge pipes

20 and 120 may be configured so that the fuel inside the high-pressure delivery pipe 18 can be discharged to the low-pressure fuel system and the discharge amount of the high-pressure pump 16 can be increased.

If it says further about the exit of the

discharge pipes

20 and 120, it is preferable that the

discharge pipes

20 and 120 are connected to the fuel tank 11 downstream from the branch part 13a of the supply pipe 13 in the low-pressure fuel system. As shown in FIG. 1, “the downstream side of the branch portion 13a of the low-pressure fuel system” means any of the low-pressure side pipe 13b, the low-pressure delivery pipe 14, the intake port 4 of the supply pipe 13, or the piping system connecting these elements. This is the place. Thereby, the high-temperature fuel recirculated from the high-pressure delivery pipe 18 by the

discharge pipes

20 and 120 is not introduced into the high-pressure pump 16 as it is, but is injected from the port injector 15 or stored in the fuel tank 11. Therefore, the fuel temperature reduction of the high-pressure pump 16 can be effectively promoted.

Claims

A fuel tank (11) for storing fuel;
A low pressure pump (12) for discharging the fuel in the fuel tank (11);
It has a port injection part (15) for injecting fuel into the intake port (4) of the engine (1) mounted on the vehicle, and the fuel discharged from the low-pressure pump (12) is supplied to the port injection part (15 Low pressure delivery pipe (14) to be fed to
A high pressure pump (16) for pressurizing and discharging the fuel discharged from the low pressure pump (12);
An in-cylinder injection part (19) for injecting fuel into the cylinder (5) of the engine (1) is supplied, and the fuel discharged from the high-pressure pump (16) is supplied to the in-cylinder injection part (19). High pressure delivery pipe (18) to
The high-pressure delivery pipe (18) is connected between the low-pressure fuel system from the fuel tank (11) through the low-pressure delivery pipe (14) to the intake port (4) and the high-pressure delivery pipe (18). A discharge pipe (20, 120) configured to be able to discharge the fuel inside the low-pressure fuel system and increase the discharge amount of the high-pressure pump (16);
A vehicle fuel injection device comprising:
A supply pipe (13) having a branch part (13a) for supplying the fuel discharged from the low pressure pump (12) to the low pressure delivery pipe (14) and the high pressure pump (16);
The discharge pipe (20, 120) is connected to the downstream side of the branch portion (13a) in the low-pressure fuel system.
The fuel injection device according to claim 1.
A flow rate adjusting unit (21) provided on the discharge pipe (20, 120) for adjusting the flow rate of fuel flowing through the discharge pipe (20, 120);
A control unit (24, 124) for controlling the operation of the flow rate adjustment unit (21),
The control unit (24, 124) acquires information on the fuel temperature in the high-pressure pump (16), and controls the operation of the flow rate adjustment unit (21) when the fuel temperature is higher than a predetermined value. Increase the flow rate,
The fuel injection device according to claim 1 or 2.
The discharge pipe (20) is connected so as to be able to discharge fuel from the high pressure delivery pipe (18) to the low pressure delivery pipe (14),
When the fuel temperature is higher than a predetermined value and the port injection section (15) of the low pressure delivery pipe (14) is stopped, the control section (24) supplies fuel to the discharge pipe (20). The flow rate adjusting unit (21) is controlled so as to flow.
The fuel injection device according to claim 3.
The discharge pipe (120) is connected to the intake port (4) so that fuel can be discharged from the high-pressure delivery pipe (18),
When the fuel temperature is higher than a predetermined value, the control unit (124) stops the port injection unit (15) of the intake port (4) to which the exhaust pipe (120) is connected and controls the flow rate. The amount of fuel supplied from the exhaust pipe (120) to the intake port (4) is controlled by the section (21), or when the fuel temperature is higher than a predetermined value, the fuel injection by the port injection section (15) The flow rate adjusting unit (21) is controlled so that the fuel flows to the exhaust pipe (120) by reducing the amount, and the intake port (21) or the port injection unit (15) is used to control the intake port (21). 4) control the amount of fuel supplied to
The fuel injection device according to claim 3.
The control unit (24, 124) acquires information on the fuel pressure inside the high pressure delivery pipe (18), and the exhaust pipe (20, 120) communicates when the fuel pressure is higher than a target fuel pressure by a predetermined amount. Controlling the flow rate adjuster (21) to
The fuel injection device for a vehicle according to any one of claims 3 to 5.
The discharge pipe (20) is connected so as to be able to discharge fuel from the high pressure delivery pipe (18) to the low pressure delivery pipe (14),
A leak mechanism (30) provided to reduce the inner diameter of the discharge pipe (20);
The fuel injection device according to claim 1 or 2.
A fuel tank (11) for storing fuel;
A low pressure pump (12) for discharging the fuel in the fuel tank (11);
It has a port injection part (15) for injecting fuel into the intake port (4) of the engine (1) mounted on the vehicle, and the fuel discharged from the low-pressure pump (12) is supplied to the port injection part (15 Low pressure delivery pipe (14) to be fed to
A high pressure pump (16) for pressurizing and discharging the fuel discharged from the low pressure pump (12);
An in-cylinder injection part (19) for injecting fuel into the cylinder (5) of the engine (1) is supplied, and the fuel discharged from the high-pressure pump (16) is supplied to the in-cylinder injection part (19). High pressure delivery pipe (18) to
The high-pressure delivery pipe (18) is connected between the low-pressure fuel system from the fuel tank (11) through the low-pressure delivery pipe (14) to the intake port (4) and the high-pressure delivery pipe (18). A discharge pipe (20, 120) configured to be able to discharge the fuel inside the low-pressure fuel system and increase the discharge amount of the high-pressure pump (16);
A flow rate adjusting unit (21) provided on the discharge pipe (20, 120) for adjusting the flow rate of fuel flowing through the discharge pipe (20, 120);
A control device for controlling the operation of a fuel injection device (10, 110) of a vehicle comprising:
Controllers (24a, 124a) for acquiring information on the fuel temperature in the high-pressure pump (16) and controlling the operation of the flow rate adjusting unit (21) to increase the flow rate when the fuel temperature is higher than a predetermined value. A control device.
The discharge pipe (20) of the fuel injection device (10) is connected so as to be able to discharge fuel from the high-pressure delivery pipe (18) to the low-pressure delivery pipe (14),
When the fuel temperature is higher than a predetermined value and the port injection part (15) of the low pressure delivery pipe (14) is stopped, the controller (24a, 124a) Controlling the flow rate adjuster (21) so that fuel flows;
The control device according to claim 8.
The discharge pipe (120) of the fuel injection device (110) is connected to the intake port (4) so as to be able to discharge fuel from the high-pressure delivery pipe (18),
When the fuel temperature is higher than a predetermined value, the controller (24a, 124a) stops the port injection section (15) of the intake port (4) to which the exhaust pipe (120) is connected, and the flow rate The amount of fuel supplied from the exhaust pipe (120) to the intake port (4) is controlled by the adjustment unit (21), or when the fuel temperature is higher than a predetermined value, the fuel by the port injection unit (15) The flow rate adjuster (21) is controlled so that the injection amount is reduced and the fuel flows through the exhaust pipe (120), and the intake port is controlled by the flow rate adjuster (21) or the port injector (15). Controlling the amount of fuel supplied to (4),
The control device according to claim 8.
The controller (24a, 124a) acquires information on the fuel pressure inside the high pressure delivery pipe (18), and the exhaust pipe (20, 120) communicates when the fuel pressure is higher than a target fuel pressure by a predetermined amount. The control device according to any one of claims 8 to 10, which controls the flow rate adjusting unit (21) as described above.