JP-2026074703-A - Fuel supply system

Abstract

[Problem] The problem is to provide a fuel supply system that ensures a stable flow rate of fuel supplied to the port injection valve. [Solution] A fuel supply system comprising: first and second low-pressure fuel pumps provided in a fuel tank for pressurizing the fuel in the fuel tank; a low-pressure fuel passage for supplying the fuel pressurized by the first and second low-pressure fuel pumps to the port injection valves of an engine; a high-pressure fuel pump for further pressurizing the fuel supplied from the low-pressure fuel passage and supplying it to the in-cylinder injection valves of the engine; and a control device for controlling the first and second low-pressure fuel pumps so that the respective fuel discharge flow rates of the first and second low-pressure fuel pumps become first and second target discharge flow rates. [Selection Diagram] Figure 3

Inventors

• 北川 雅也
• 杉本 元浩
• 山城 浩幹
• 井戸側 正直
• 内田 孝宏

Assignees

• トヨタ自動車株式会社

Dates

Publication Date

20260507

Application Date

20241021

Claims (4)

1. A first and second low-pressure fuel pump, provided inside the fuel tank, pressurizes the fuel inside the fuel tank. A low-pressure fuel passage that supplies fuel pressurized by the first and second low-pressure fuel pumps to the engine's port injection valves, A high-pressure fuel pump further pressurizes the fuel supplied from the low-pressure fuel passage and supplies it to the in-cylinder injection valve of the engine, The system includes a control device that controls the first and second low-pressure fuel pumps so that the fuel discharge flow rates of the first and second low-pressure fuel pumps become the first and second target discharge flow rates, respectively. The control device is A drive control unit controls the first low-pressure fuel pump to operate and the second low-pressure fuel pump to stop when the required fuel flow rate for the port injection valve is below a threshold, and controls the first low-pressure fuel pump to operate and stops when the required flow rate is greater than the threshold, to operate and stops. The system includes a pressure-boosting control unit that, when there is a request for fuel pressure boosting by the high-pressure fuel pump, increases the first target discharge flow rate in the first driving state compared to when there is no such request, and increases at least one of the first and second target discharge flow rates in the second driving state. Fuel supply system.
2. The control device includes a calculation unit that calculates the first and second target discharge flow rates, The fuel supply system according to claim 1, wherein the calculation unit calculates the first target discharge flow rate in the first driving state, including a first feedback control amount based on the deviation between the target fuel pressure and the actual fuel pressure of the fuel supplied to the port injection valve, and calculates the second target discharge flow rate in the second driving state, including a second feedback control amount based on the deviation, and calculates the first target discharge flow rate by setting the first feedback control amount to a constant value independent of the deviation.
3. The first feedback control variable includes a first proportional term and a first integral term, The second feedback control variable includes a second proportional term and a second integral term, The fuel supply system according to claim 2, wherein the calculation unit calculates the first feedback control amount as a constant value by fixing the first proportional term and the first integral term to the respective values of the first proportional term and the first integral term when the requested flow rate exceeds the threshold if the deviation has not converged when the requested flow rate exceeds the threshold, and by fixing the first integral term to the value of the first integral term when the requested flow rate exceeds the threshold and setting the first proportional term to zero when the deviation has converged when the requested flow rate exceeds the threshold.
4. The calculation unit calculates, based on the requested flow rate, a first shared flow rate, which is the portion of the requested flow rate handled by the first low-pressure fuel pump, and a second shared flow rate, which is the portion of the requested flow rate handled by the second low-pressure fuel pump. If the requested flow rate is less than or equal to the threshold, the first shared flow rate is calculated to increase as the requested flow rate increases, and the second shared flow rate is calculated to be zero. If the requested flow rate is greater than the threshold, the first shared flow rate is calculated to be a constant value, and the second shared flow rate is calculated to increase as the requested flow rate increases. The first target discharge flow rate includes the first shared flow rate and the first feedback control amount. The fuel supply system according to claim 2 or 3, wherein the second target discharge flow rate includes the second shared flow rate and the second feedback control amount.

Description

This invention relates to a fuel supply system. There are first and second low-pressure fuel pumps installed in the vehicle's fuel tank, which pressurize the fuel in the fuel tank and supply it to the engine (see, for example, Patent Document 1). Japanese Patent Publication No. 2011-012615 This is a schematic diagram of the fuel supply system.This map defines the relationship between the power output required by the engine and the required fuel flow rate for the port injection valves.This is a flowchart illustrating height adjustment control.This flowchart illustrates the switching control from the first drive state to the second drive state. [Outline configuration of the fuel supply system] Figure 1 is a schematic diagram of the fuel supply system A. The fuel supply system A includes an engine 10, a fuel tank 23, a first low-pressure fuel pump 24a, a second low-pressure fuel pump 24b, a low-pressure pipe 25, a low-pressure delivery pipe 26, a high-pressure delivery pipe 36, fuel pressure sensors 28 and 38, and a high-pressure fuel pump 40, etc. Engine 10 is a spark-ignition type four-cylinder gasoline engine equipped with in-cylinder injection valves 37 that inject fuel into each cylinder, and port injection valves 27 that inject fuel into each intake port. Engine 10 is not limited to four cylinders; it may also be a V-type engine or a diesel engine. Furthermore, engine 10 is equipped with a camshaft CPS that drives the intake valve or exhaust valve in conjunction with a crankshaft linked to multiple pistons. The fuel tank 23 stores gasoline, which is the fuel. The first low-pressure fuel pump 24a and the second low-pressure fuel pump 24b are installed inside the fuel tank 23. The first low-pressure fuel pump 24a and the second low-pressure fuel pump 24b are pumps with the same performance, such as head, but are not limited to these. The first low-pressure fuel pump 24a pressurizes the fuel and discharges it to the low-pressure pipe 25 via a branch pipe 24ap. The second low-pressure fuel pump 24b pressurizes the fuel and discharges it to the low-pressure pipe 25 via a branch pipe 24bp. The base ends of the branch pipes 24ap and 24bp are connected to the first low-pressure fuel pump 24a and the second low-pressure fuel pump 24b, respectively. The ends of the branch pipes 24ap and 24bp are connected to the low-pressure pipe 25. The fuel discharged into the low-pressure pipe 25 is supplied to the port injection valve 27 via the low-pressure delivery pipe 26, and also to the high-pressure fuel pump 40 via the branch pipe 25a that branches off from the low-pressure pipe 25. The high-pressure pump 40 pressurizes the fuel supplied from the branch pipe 25a and discharges it into the high-pressure delivery pipe 36. The fuel pressurized by the high-pressure pump 40 is then supplied to the in-cylinder injection valve 37 via the high-pressure delivery pipe 36. The fuel pressure sensors 28 and 38 detect the fuel pressure in the low-pressure delivery pipe 26 and the high-pressure delivery pipe 36, respectively. The ECU 100 acquires the detected values from the fuel pressure sensors 28 and 38. The ECU 100 comprises a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and rewritable non-volatile memory. The CPU executes a program stored in the ROM, thereby performing the height-raising control and switching control described later. These controls are performed by a drive control unit, height-raising control unit, and calculation unit, which are functionally realized by the CPU, ROM, RAM, and non-volatile memory. Further details will be provided later. Furthermore, the ECU 100 changes the in-cylinder injection ratio, which is the ratio of the fuel injected from the in-cylinder injection valve 37 to the total fuel injection amount, according to the operating range of the engine 10. For example, in the low-load operating range of the engine 10, the in-cylinder injection ratio is 0%, in the high-load range it is 100%, and in the medium-load range it is set to an intermediate value. The high-pressure pump 40 is equipped with a cylinder 41, a plunger 42, a pressurizing chamber 43, an intake passage 45, a discharge passage 47, a relief passage 49, an intake valve 50, a discharge valve 60, and a relief valve 70. The plunger 42 is biased by a spring toward the cam CP, which rotates with the cam shaft CPS, and reciprocates within the cylinder 41 as the cam CP rotates. The pressurizing chamber 43 is defined by the cylinder 41 and the plunger 42. The volume of the pressurizing chamber 43 decreases as the plunger 42 rises. The volume of the pressurizing chamber 43 increases as the plunger 42 descends. The intake passage 45 connects the branch pipe 25a, which branches off from the low-pressure pipe 25, to the pressurizing chamber 43. The intake passage 45 is equipped with a pulsation damper 44 to suppress fuel pressure pulsation. The relief passage 49 connects the pressurizing chamber 43 to the high-pres