Fuel accumulation device and fuel supply system

Abstract

To provide a fuel accumulation device and a fuel supply system which suppress problems caused by air bubbles in an exhaust system.SOLUTION: A fuel supply system 1 comprises a fuel accumulation device 5. The fuel accumulation device 5 has a pressure accumulation vessel 21, a pressure control valve 22, and a filter 23. Fuel passes through the filter 23 from the accumulation vessel 21 and reaches the pressure control valve 22. When the pressure control valve 22 opens, the fuel passes through the filter 23 and returns to a fuel tank 12 through a return passage 19. Suppression means suppress air bubbles from reaching the filter 23. By suppressing the air bubbles reaching the filter 23, problems caused by the air bubbles are suppressed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The disclosure herein relates to a fuel accumulator and fuel delivery system for supplying fuel to an engine. [Background technology]

[0002] Patent Documents 1, 2, and 3 disclose a fuel supply device and a technology for separating air bubbles in a pressure accumulator from fuel by utilizing the buoyancy of the air bubbles. The separated air bubbles are discharged downstream together with the fuel. The contents of the prior art documents are incorporated by reference as explanations of the technical elements in this specification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-162891 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-36078 [Patent Document 3] Japanese Patent Application Publication No. 11-280594 Summary of the Invention [Problem to be solved by the invention]

[0004] The fuel supply device may include a discharge system that discharges fuel from the pressure accumulator. The discharge system may be provided with a filter. Furthermore, the discharge system may be provided with a pressure control valve. When separated air bubbles reach the discharge system, problems may occur. In particular, problems become more pronounced when a large amount of separated and accumulated air bubbles reach the discharge system. One problem is that when air bubbles reach the filter, the pressure loss of the filter increases. Another problem is that when air bubbles reach the pressure control valve, the pressure control valve's pressure regulation performance decreases. Yet another problem is that when the filter mesh is set relatively large to suppress the pressure loss of the filter, the performance of capturing fine foreign matter decreases. In the above-mentioned perspectives and in other perspectives not mentioned, further improvements are required in fuel pressure accumulators and fuel supply systems.

[0005] One disclosed object is to provide a fuel accumulator and a fuel supply system that suppresses problems caused by air bubbles in the exhaust system. [Means for solving the problem]

[0006] The fuel accumulator disclosed herein includes a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) that is provided in the pressure accumulator vessel and opens in response to the fuel pressure in the pressure accumulator chamber to discharge fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) that is provided between the pressure accumulator chamber and the pressure control valve and has a filtering member (23a) that filters the fuel discharged from the pressure accumulator chamber; and air bubble arrival suppression means (21L, 224, 324, 424, 562, 625S, 723, 826, 926, A26) that suppresses the amount of air bubbles that reach the filtering member while the internal combustion engine is in operation.

[0007] According to the disclosed fuel accumulator, the bubble arrival suppression means suppresses the amount of bubbles that reach the filter member while the internal combustion engine is operating. In other words, the amount of bubbles that reach the filter and the pressure control valve is suppressed. Therefore, the amount of bubbles that reach the filter member while the internal combustion engine is operating is suppressed. As a result, problems caused by bubbles reaching the filter and the pressure control valve are suppressed.

[0008] The fuel accumulator disclosed herein includes a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) that is provided in the pressure accumulator vessel and opens in response to the fuel pressure in the pressure accumulator vessel to discharge fuel from the pressure accumulator vessel; a filter (23, 723, 823, A23) that is provided between the pressure accumulator vessel and the pressure control valve and has a filtering member (23a) that filters the fuel discharged from the pressure accumulator vessel; and a lower installation portion (21L, 224, 324, 424) that positions the pressure control valve and the filter below the pressure accumulator vessel in the direction of gravity.

[0009] In the disclosed fuel accumulator, the lower installation portion positions the pressure control valve and the filter at the lower end of the pressure vessel in the direction of gravity. As a result, air bubbles rise due to their own buoyancy and are moved away from the filter element, which is positioned at the lower end in the direction of gravity. This reduces the amount of air bubbles that reach the filter element during operation of the internal combustion engine. As a result, problems caused by air bubbles reaching the filter and the pressure control valve are reduced.

[0010] The fuel supply system disclosed herein includes a high-pressure pump (15) that pressurizes fuel to an injection pressure; a pressure accumulator (21) that defines a pressure accumulator chamber into which the fuel pressurized to the injection pressure is introduced and is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) that is provided in the pressure accumulator and opens in response to the fuel pressure in the pressure accumulator chamber to discharge fuel from the pressure accumulator; a filter (23, 723, 823, A23) that is provided between the pressure accumulator chamber and the pressure control valve and has a filtering member (23a) that filters the fuel discharged from the pressure accumulator chamber; and a control device (6) that controls the high-pressure pump, the control device including at least one processor, and that uses the processor to perform bubble suppression control (562) that operates the high-pressure pump to discharge air bubbles from the fuel system after fuel has been introduced into a fuel system including the pressure accumulator and before the internal combustion engine is operated.

[0011] In the disclosed fuel supply system, the control device executes bubble suppression control using a processor. The bubble suppression control operates a high-pressure pump to discharge bubbles from a fuel system including a pressure accumulator. The bubble suppression control is executed after fuel is introduced into the fuel system and before the internal combustion engine is started. In other words, the bubble suppression control is executed before the internal combustion engine is started. Therefore, the amount of bubbles reaching the filtering element during the operation of the internal combustion engine is suppressed. As a result, problems caused by bubbles reaching the filter and the pressure control valve are suppressed.

[0012] The fuel accumulator disclosed herein includes a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) that is provided in the pressure accumulator vessel and opens in response to the fuel pressure in the pressure accumulator vessel to discharge fuel from the pressure accumulator vessel; a filter (23, 723, 823, A23) that is provided between the pressure accumulator vessel and the pressure control valve and has a filtering member (23a) that filters the fuel discharged from the pressure accumulator vessel; and a retention suppression unit (21S, 625S, 723) that is provided in the pressure accumulator vessel and suppresses retention of air bubbles upstream of the filter in the direction of fuel flow in the pressure accumulator vessel toward the pressure control valve.

[0013] According to the disclosed fuel accumulator, a retention suppression unit is provided in the accumulator vessel. The retention suppression unit suppresses the retention of bubbles upstream of the filter. This reduces the amount of bubbles that reach the filter element while the internal combustion engine is running. As a result, problems caused by bubbles reaching the filter and the pressure control valve are reduced.

[0014] The fuel accumulator disclosed herein includes a pressure accumulator vessel (21) that defines a pressure accumulator chamber into which fuel pressurized to an injection pressure is introduced and is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) that is provided in the pressure accumulator vessel and opens in response to the fuel pressure in the pressure accumulator vessel to discharge fuel from the pressure accumulator vessel; a filter (23, 723, 823, A23) that is provided between the pressure accumulator vessel and the pressure control valve and has a filtering member (23a) that filters the fuel discharged from the pressure accumulator vessel; and a bubble capturing section (826, 926, A26) that is provided in the pressure accumulator vessel and captures air bubbles before they reach the filtering member, thereby reducing the amount of air bubbles that reach the filtering member during operation of the internal combustion engine.

[0015] According to the disclosed fuel accumulator, the pressure accumulator vessel is provided with a bubble trapping portion. The bubble trapping portion traps bubbles before they reach the filtering member. This reduces the amount of bubbles that reach the filtering member during operation of the internal combustion engine. As a result, problems caused by bubbles reaching the filter and the pressure control valve are reduced.

[0016] The various embodiments disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify the correspondence with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a block diagram of a fuel supply system according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a fuel accumulator. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing a fuel accumulator. [Figure 4] FIG. 4 is a cross-sectional view showing a fuel accumulator according to a second embodiment. [Figure 5] FIG. 10 is a cross-sectional view showing a fuel accumulator according to a third embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing a fuel accumulator according to a fourth embodiment. [Figure 7] 10 is a flowchart of a fuel supply system according to a fifth embodiment. [Figure 8] FIG. 10 is an enlarged cross-sectional view showing a fuel accumulator according to a sixth embodiment. [Figure 9] FIG. 12 is an enlarged cross-sectional view showing a fuel accumulator according to a seventh embodiment. [Figure 10] FIG. 13 is an enlarged cross-sectional view showing a fuel accumulator according to an eighth embodiment. [Figure 11] FIG. 13 is an enlarged cross-sectional view showing a fuel accumulator according to a ninth embodiment. [Figure 12] FIG. 22 is an enlarged cross-sectional view showing a fuel accumulator according to a tenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digits. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0019] First embodiment FIG. 1 is a block diagram of a fuel supply system 1. In FIG. 1, the fuel supply system 1 supplies fuel to an engine 2. The engine 2 is an internal combustion engine. The engine 2 is a so-called diesel engine or a gasoline engine. The engine 2 receives pressurized fuel in a main combustion chamber or a sub-combustion chamber and burns the fuel. The fuel supply system 1 includes a fuel system 3 and a control device 6. The fuel system 3 includes members and devices having a passage through which the fuel is introduced. The fuel system 3 includes a fuel supply device 4 and a fuel accumulator 5. In the following description, the fuel supply device 4 will also be referred to as a supply device 4. In the following description, the fuel accumulator 5 will also be referred to as an accumulator 5.

[0020] The pressure accumulator 5 stores the fuel pressurized to injection pressure by the supply device 4. The pressure accumulator 5 supplies the pressurized fuel to the engine 2. The fuel supply system 1 injects the pressurized fuel into the main combustion chamber or the auxiliary combustion chamber of the engine 2. The auxiliary combustion chamber is sometimes also called a pre-combustion chamber or auxiliary chamber. When the fuel supply system 1 injects fuel into the auxiliary combustion chamber, it is also called an IDI (Indirect Injection) diesel engine system. The supply device 4 pressurizes the fuel and supplies it to the pressure accumulator 5. The supply device 4 maintains the pressure of the fuel stored in the pressure accumulator 5 at a predetermined pressure or higher. The control device 6 controls the supply device 4 and the pressure accumulator 5 to operate the engine 2.

[0021] The supply device 4 includes a fuel tank 12, a low-pressure pump 13, a low-pressure passage 14, a high-pressure pump 15, and a high-pressure passage 17. The fuel tank 12 stores fuel. The low-pressure pump 13 draws fuel stored in the fuel tank 12 and discharges it to the low-pressure passage 14. The low-pressure passage 14 is provided between the low-pressure pump 13 and the high-pressure pump 15 and fluidly connects them. In the following description, multiple passages are provided by pipes, passages penetrating members, grooves between multiple members, or the like. The high-pressure pump 15 pressurizes the fuel supplied from the low-pressure passage 14 and supplies it to the pressure accumulator 5. The high-pressure pump 15 pressurizes the fuel to a predetermined injection pressure. The high-pressure passage 17 fluidly connects the high-pressure pump 15 and the pressure accumulator 5.

[0022] The high-pressure pump 15 is a so-called plunger pump that includes a plunger 31 as a pressurizing mechanism. The high-pressure pump 15 pressurizes the fuel in a pressurizing chamber using the plunger 31. The high-pressure pump 15 pressurizes the fuel to injection pressure. The high-pressure pump 15 includes a cam 32 and a motor 33 as a power source. The cam 32 rotates as the motor 33 rotates. The cam 32 reciprocates the plunger 31. As a result, the plunger 31 pressurizes the fuel. Instead of the motor 33, the engine 2 and a starter motor may be used as a power source.

[0023] The high-pressure pump 15 includes an intake valve mechanism 34. The intake valve mechanism 34 adjusts the amount of fuel intake to the pressurizing mechanism. The intake valve mechanism 34 adjusts the discharge pressure of the high-pressure pump 15. The intake valve mechanism 34 includes a check valve 35 and an electromagnetic driver 36. The control device 6 controls whether the electromagnetic driver 36 is energized or de-energized. The check valve 35 allows fuel to flow into the pressurizing mechanism and prevents fuel from returning from the pressurizing mechanism. The electromagnetic driver 36 is connected to the valve mechanism of the check valve 35. The check valve 35 and the electromagnetic driver 36 enable external control of the fuel flow into and return to the pressurizing mechanism. As a result, the discharge pressure of the high-pressure pump 15 is controlled by the control device 6 via the intake valve mechanism 34.

[0024] The high-pressure pump 15 includes a discharge valve mechanism 37. The discharge valve mechanism 37 adjusts the discharge of fuel from the pressurizing mechanism to the pressure accumulator 5. The discharge valve mechanism 37 includes a first check valve 38 and a second check valve 39. The first check valve 38 fluidly connects the pressurizing mechanism and the pressure accumulator 5. The first check valve 38 allows fuel to flow from the pressurizing mechanism to the pressure accumulator 5 and prevents fuel from flowing in the reverse direction. The first check valve 38 is a so-called forward check valve. The second check valve 39 fluidly connects the downstream side of the first check valve 38 to the intake valve mechanism 34. The second check valve 39 allows fuel to flow from the downstream side of the first check valve 38 to the intake valve mechanism 34 and prevents fuel from flowing in the reverse direction. The second check valve 39 functions as a relief valve that returns excess fuel.

[0025] The pressure accumulator 5 includes a pressure accumulator vessel 21 , a pressure control valve 22 , a filter 23 , an injection device 18 , and a return passage 19 .

[0026] The pressure accumulator vessel 21 defines a pressure accumulator chamber 21v into which fuel pressurized to injection pressure is introduced. The pressure accumulator vessel 21 is fluidly connected to the high-pressure pump 15. The pressure accumulator vessel 21 receives high-pressure fuel from the high-pressure pump 15 through the high-pressure passage 17. The pressure accumulator vessel 21 stores a predetermined amount of high-pressure fuel.

[0027] The pressure accumulator vessel 21 includes a main trunk portion 21a and a plurality of branch portions 21b. The main trunk portion 21a is provided by a connecting pipe that serves as a trunk connecting the plurality of branch portions 21b. The main trunk portion 21a is provided by a main pipe member in the pressure accumulator vessel 21. The plurality of branch portions 21b are a plurality of branch pipe members that branch off from the main trunk portion 21a. An injection device 18 is connected to each of the plurality of branch portions 21b. Thus, the fuel supply system 1 includes a plurality of injection devices 18. The pressure accumulator vessel 21 is fluidly connected to the plurality of injection devices 18. The pressure accumulator vessel 21 is sometimes called a common rail.

[0028] A plurality of injectors 18 supplies fuel to the engine 2. In the illustrated example, three branches 21a and three injectors 18 are illustrated. The number of outlet pairs, each including one branch 21a and one injector 18, corresponds to the number of cylinders of the engine 2.

[0029] The pressure control valve 22 is provided at one end of the pressure accumulator container 21. When the fuel pressure inside the pressure accumulator container 21 becomes excessively high, the pressure control valve 22 releases the fuel to the return passage 19. The return passage returns the fuel to the fuel tank 12. The filter 23 filters the fuel flowing from the pressure accumulator container 21 to the pressure control valve 22 and captures foreign matter. The pressure control valve 22 and the filter 23 provide a discharge system for the fuel supply system 1.

[0030] The control unit 6 (ECU) controls the supply device 4 and the pressure accumulator 5. The control unit 6 controls the supply device 4 and the pressure accumulator 5 so as to properly supply fuel to the engine 2. The control unit 6 provides a control circuit for properly functioning the fuel supply system 1 including the engine 2. The control circuit executes a control method using a circuit configuration and / or a processor and a program stored in a memory. The control unit 6 receives a detection signal from at least one sensor and operates at least one actuator. The sensor may include a pressure sensor that detects the pressure of the fuel and / or a temperature sensor that detects the temperature of the fuel. The actuator may include a motor 33, an electromagnetic driver 36, and / or an injector 18.

[0031] The control device in this specification may also be referred to as an Electronic Control Unit (ECU). The control device or control system is provided by (a) an algorithm as a plurality of logics called an if-then-else format, or (b) an algorithm as a trained model tuned by machine learning, for example, a neural network.

[0032] The control device is provided by a control system including at least one computer. The control system may include multiple computers linked by data communication devices. The computer includes at least one processor that is hardware (a hardware processor). The hardware processor can be provided by (i), (ii), or (iii) below.

[0033] (i) A hardware processor may be at least one processor core that executes a program stored in at least one memory. In this case, a computer is provided with at least one memory and at least one processor core. The processor core is called a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a RISC-CPU, etc. Memory is also called a storage medium. Memory is a non-transitory, tangible storage medium that non-temporarily stores "programs and / or data" that can be read by a processor. Storage media are provided by semiconductor memory, magnetic disks, optical disks, etc. Programs may be distributed independently or as storage media on which the programs are stored.

[0034] (ii) A hardware processor may be a hardware logic circuit. In this case, a computer is provided by a digital circuit including a large number of programmed logic units (gate circuits). The digital circuit is also called a logic circuit array, for example, ASIC: Application-Specific Integrated Circuit, FPGA: Field Programmable Gate Array, SoC: System on a Chip, PGA: Programmable Gate Array, CPLD: Complex Programmable Logic Device, etc. The digital circuit may include a memory that stores programs and / or data. A computer may be provided by an analog circuit. A computer may be provided by a combination of digital and analog circuits.

[0035] (iii) The hardware processor may be a combination of (i) and (ii) above. (i) and (ii) may be located on different chips or on a common chip. In these cases, the part (ii) is also called an accelerator.

[0036] Fig. 2 is a cross-sectional view showing the pressure accumulator 5. Fig. 2 shows the pressure accumulator 5 in a state where it is mounted on the engine 2. The figure illustrates an orthogonal coordinate system including an X-axis, a Y-axis, and a Z-axis. The downward direction of the Y-axis is the direction of gravity. The X-axis and the Z-axis are horizontal. In the figure, a central axis CX21 of a pressure accumulator vessel 21, which will be described later, is disposed on the XY plane.

[0037] The pressure accumulator vessel 21 is made of metal. The pressure accumulator vessel 21 is a cylindrical member. Due to its cylindrical shape, the pressure accumulator vessel 21 defines a central axis CX21. In the drawing, the central axis CX21 is indicated by a dashed line. The direction of the central axis CX21 is the axial direction of the pressure accumulator vessel 21. The central axis CX21 is the central axis of the main trunk portion 21a. The pressure accumulator vessel 21 defines a pressure accumulator chamber 21v therein. The pressure accumulator vessel 21 has an inner surface that defines the pressure accumulator chamber 21v. The inner surface that defines the pressure accumulator chamber 21v is the inner surface of a straight pipe. The upper side of the inner surface in the direction of gravity is also referred to as the upper surface 21UW. The pressure accumulator chamber 21v has a fuel inlet for fluid communication with the supply device 4. The pressure accumulator chamber 21v receives high-pressure fuel from the supply device 4. The fuel inlet is not shown in the drawing. The pressure accumulator chamber 21v stores high-pressure fuel. The amount of fuel stored is a predetermined amount that exceeds the amount of fuel injected for several times. The pressure accumulator chamber 21v is in fluid communication with the plurality of connecting portions 21a.

[0038] The pressure accumulator vessel 21 has a pressure control valve 22 at one end in the axial direction. The pressure control valve 22 is fixed by being screwed to the pressure accumulator vessel 21 so as to close the opening at the right end of the pressure accumulator vessel 21 in the figure. The pressure control valve 22 has an end face facing the pressure accumulator chamber 21v. The pressure control valve 22 defines a fuel passage that opens at the end face.

[0039] The filter 23 is provided between the pressure control valve 22 and the pressure accumulator chamber 21v. The filter 23 is fixed to an end of the pressure control valve 22. The filter 23 protrudes from the end face of the pressure control valve 22 toward the pressure accumulator chamber 21v.

[0040] In the figure, the dashed line indicates the horizontal plane HL. The horizontal plane HL is parallel to the XZ plane. As shown in the figure, the pressure accumulator vessel 21 is disposed with the central axis CX21 inclined with respect to the horizontal plane HL. As a result, the pressure accumulator chamber 21v of the pressure accumulator vessel 21 forms an upper end 21U in the direction of gravity and a lower end 21L in the direction of gravity. The upper end 21U is the uppermost part of the pressure accumulator chamber 21v in the direction of gravity. The lower end 21L is the lowermost part of the pressure accumulator chamber 21v in the direction of gravity. The lower end 21L provides a bubble arrival suppression means that suppresses the amount of bubbles that reach the filter member 23a while the engine 2 is operating.

[0041] The pressure accumulator vessel 21 is inclined so that the filter 23 is positioned downward in the direction of gravity. The pressure accumulator vessel 21 is inclined so that both the pressure control valve 22 and the filter 23 are positioned downward in the direction of gravity. In other words, the filter 23 is disposed near the lower end 21L of the pressure accumulator vessel 21, out of the upper end 21U and the lower end 21L. The filter 23 protrudes toward the pressure accumulator chamber 21v from an end face adjacent to the lower end 21L of the inner surface that defines the pressure accumulator chamber 21v. The filter 23 extends along the central axis CX21.

[0042] The central axis CX21 is inclined at an inclination angle SA21 with respect to the horizontal plane HL. The inclination angle SA21 can be from several degrees to a dozen degrees. The inclination angle SA21 can be adjusted within a range that does not include 0 degrees. The inclination angle SA21 can be adjusted within a range that is greater than 0 degrees and equal to or less than 90 degrees. Due to the inclination of the central axis CX21, the upper surface 21UW also extends in an inclined manner in the axial direction. The upper surface 21UW extends parallel to the central axis CX21. The upper surface 21UW is also inclined on the upper side of the filter 23. The upper surface 21UW is uniformly inclined from the upper region of the filter 23 to the upper end 21U.

[0043] 3 is an enlarged cross-sectional view showing the portion indicated by the arrow III in FIG. 2. In the figure, air bubbles in the pressure accumulator chamber 21v are illustrated by white circles. Note that the air bubbles in the figure are merely an example. During operation of the fuel supply system 1, air bubbles may reach the vicinity of the filter 23 as fine bubbles smaller than those illustrated, or as columnar gas masses larger than those illustrated.

[0044] The pressure control valve 22 has a shape that can be called a column or a cylinder. The pressure control valve 22 is screwed onto an end of the pressure accumulator vessel 21. Due to its cylindrical shape, the pressure control valve 22 defines a central axis. The central axis of the pressure control valve 22 coincides with the central axis CX21 of the pressure accumulator vessel 21.

[0045] The pressure control valve 22 includes a body 22a, a valve seat member 22b, and a seal member 22c. The body 22a is a cylindrical member with a bottom. One end of the body 22a that faces the pressure accumulator vessel 21 is open, and the other end, which is also the end of the pressure accumulator 5, is closed. The body 22a is made of metal. The body 22a is fixed to the pressure accumulator vessel 21 by being screwed onto it. The valve seat member 22b is fixed between the pressure accumulator vessel 21 and the body 22a. The valve seat member 22b is a cylindrical member. The valve seat member 22b is made of metal. The valve seat member 22b has an opening 22e on an end surface 22d that faces the pressure accumulator chamber 21v. The opening 22e provides a fuel inlet. The valve seat member 22b provides a valve seat 22f for the valve mechanism. A volume chamber 22g is defined between the body 22a and the valve seat member 22b to accommodate a movable mechanism for the valve mechanism. The volume chamber 22g is fluidly connected to the fuel tank 12 via the return passage 19. The volume chamber 22g provides a low-pressure chamber with a lower pressure than the pressure accumulator chamber 21v. The pressure of fuel in the volume chamber 22g is lower than the pressure of fuel in the pressure accumulator chamber 21v. The movable mechanism includes a movable valve element 22h and a spring 22i. The movable valve element 22h is a ball valve. The spring 22i applies a bias force to the movable valve element 22h. A retainer member may be disposed between the movable valve element 22h and the spring 22i. Furthermore, the pressure control valve 22 has a discharge passage 22k penetrating the body 22a and the pressure accumulator container 21. The discharge passage 22k is fluidly connected to the return passage 19.

[0046] The filter 23 includes a filtering member 23a and a non-filtering member 23b. The filtering member 23a has a cylindrical shape. Due to its cylindrical shape, the filtering member 23a defines a central axis CX23. The central axis CX23 coincides with the central axis CX21 of the pressure accumulator vessel 21. Therefore, the central axis CX21 of the pressure accumulator vessel 21 and the central axis CX23 of the filter 23 are all inclined. The central axis CX23 also coincides with the central axis of the pressure control valve 22. Therefore, the central axis CX21 of the pressure accumulator vessel 21, the central axis CX23 of the filter 23, and the central axis of the pressure control valve 22 are all inclined. The non-filtering member 23b is a frame member that extends the filtering member 23a. The non-filtering member 23b is provided by a cylindrical body. The non-filtering member 23b is press-fitted into an opening 22e of the body 22a through the opening 22e, and is thereby fixed to the body 22a in a liquid-tight manner. As a result, only the fuel that has passed through the filtering member 23a from the pressure accumulator chamber 21v can reach the valve formed by the valve seat 22f and the movable valve body 22h. The non-filtering member 23b is fixed to the end face 22d of the pressure control valve 22. In this embodiment, the filter 23 is fixed to the pressure control valve 22 by press-fitting the non-filtering member 23b into the valve seat member 22b.

[0047] When the pressure in the accumulator chamber 21v rises excessively, the fuel moves the movable valve element 22h against the spring 22i. The fuel pressure that moves the movable valve element 22h against the spring 22i is called the set pressure. When the movable valve element 22h moves, the movable valve element 22h lifts from the valve seat 22f, opening the pressure control valve 22. When the pressure control valve 22 is open, the fuel in the accumulator chamber 21v is filtered by the filter 23 and flows into the volume chamber 22g. The fuel that flows into the volume chamber 22g returns to the fuel tank 12 via the discharge passage 22k and the return passage 19.

[0048] The accumulator chamber 21v may be filled with fuel and air bubbles. For example, after the fuel supply system 1 is assembled in a factory, the accumulator chamber 21v may be filled with fuel and air bubbles. Air bubbles may also be generated in the fuel. In these cases, the air bubbles rise within the accumulator chamber 21v due to their own buoyancy. Air bubbles also rise within the accumulator chamber 21v near the filter 23 due to their own buoyancy. Furthermore, the air bubbles gradually rise along the upper surface 21UW. A portion of the accumulator chamber 21v is also present above the filter 23. Therefore, even within the accumulator chamber 21v located above the filter 23, the air bubbles rise in a direction away from the filter 23. In particular, even within the accumulator chamber 21v located above the filter member 23a, the air bubbles rise in a direction away from the filter member 23a. As a result, the amount of air bubbles reaching the filter member 23a of the filter 23 during operation of the engine 2 is reduced. The upper surface 21UW allows air bubbles to rise in the fuel. The upper surface 21UW is also called the inclined surface 21S. The upper surface 21UW, i.e., the inclined surface 21S, provides a bubble arrival suppression means for suppressing the amount of air bubbles that reach the filtering member 23a while the engine 2 is operating by keeping air bubbles away from the filter 23.

[0049] In this embodiment, the fuel accumulator 5 has a lower end 21L as a lower installation portion. The lower installation portion positions the pressure control valve 22 and the filter 23 below the pressure accumulator vessel 21 in the direction of gravity. The pressure accumulator vessel 21 extends in the axial direction and has a central axis CX21 inclined at an inclination angle SA21 with respect to a horizontal plane HL. The pressure accumulator vessel 21 is positioned below the direction of gravity by the inclination angle SA21. The pressure accumulator vessel 21 has a lower end 21L of the pressure accumulator vessel 21 that provides the lower installation portion. The lower installation portion positions the pressure control valve 22 and the filter 23 below the pressure accumulator vessel 21 in the direction of gravity. As a result, air bubbles rise due to their own buoyancy and are moved away from the filter member 23a, which is positioned below the direction of gravity. Therefore, the amount of air bubbles reaching the filter member 23a during operation of the engine 2 is reduced. As a result, problems caused by air bubbles reaching the filter 23 and the pressure control valve 22 are reduced.

[0050] In this embodiment, the upper surface 21UW, i.e., the inclined surface 21S, is provided on the pressure accumulator vessel 21. The inclined surface 21S guides air bubbles from the upper surface 21UW to the filtering member 23a. The inclined surface 21S provides a retention suppression portion. The retention suppression portion suppresses air bubbles from remaining upstream of the filter 23 in relation to the direction of fuel flow in the pressure accumulator chamber 21v toward the pressure control valve 22.

[0051] In this embodiment, a retention suppression unit is provided in the pressure accumulator vessel 21. The retention suppression unit suppresses retention of air bubbles upstream of the filter 23. The retention suppression unit is upstream of the filtering member 23a and suppresses retention of air bubbles in the vicinity of the filtering member 23a. Here, the vicinity of the filtering member 23a is a distance that allows air bubbles to reach the filtering member 23a when the pressure control valve 22 is open. The inclined surface 21S keeps air bubbles away from the vicinity of the filtering member 23a. Therefore, the amount of air bubbles that reach the filtering member 23a while the engine 2 is operating is suppressed. As a result, problems caused by air bubbles reaching the filter 23 and the pressure control valve 22 are suppressed.

[0052] According to this embodiment, problems caused by air bubbles reaching the exhaust system are suppressed. From one perspective, an increase in pressure loss in the filter 23 due to air bubbles reaching the filtering member 23a of the filter 23 is suppressed. From another perspective, the amount of air bubbles reaching the pressure control valve 22 is also suppressed, thereby suppressing fluctuations in the pressure regulation performance of the pressure control valve 22. In particular, a decrease in the pressure regulation performance of the pressure control valve 22 due to air bubbles reaching the pressure control valve 22 is suppressed. From yet another perspective, the size of the filter mesh of the filter 23 can be set in consideration of the required foreign matter collection performance, without considering an increase in pressure loss due to air bubbles.

[0053] Second embodiment This embodiment is a modification based on the preceding embodiment. In the preceding embodiment, the central axis CX21 of the pressure accumulator vessel 21 and the central axis CX23 of the filter 23 are both inclined. Instead, in this embodiment, the central axis CX21 of the pressure accumulator vessel 21 and the central axis CX23 of the filter 23 intersect, and the central axis CX23 of the filter 23 is inclined.

[0054] FIG. 4 is a cross-sectional view showing a pressure accumulator 5 of a second embodiment. In FIG. 4, the pressure accumulator vessel 21 is arranged so that the main trunk portion 21a extends horizontally. Therefore, the central axis CX21 of the pressure accumulator vessel 21 extends along the horizontal direction. The pressure accumulator vessel 21 may be arranged so that it is inclined with respect to the horizontal direction. When the central axis CX21 is inclined, the inclination angle of the central axis CX21 is smaller than the angle between the horizontal and a central axis CX224 of a discharge branch portion 224, which will be described later. In other words, the central axis CX21 of the pressure accumulator vessel 21 is closer to horizontal than the central axis CX224. The attitude of the pressure accumulator vessel 21 is approximately horizontal. The pressure accumulator vessel 21 is provided with a plug member 225 that closes one axial end.

[0055] The pressure accumulator vessel 21 includes a discharge branch portion 224. The discharge branch portion 224 is provided so as to branch off from the main trunk portion 21a. The discharge branch portion 224 is a branch portion for providing a discharge system including the pressure control valve 22 and the filter 23.

[0056] The discharge branch portion 224 extends downward in the direction of gravity relative to the main trunk portion 21a. The discharge branch portion 224 hangs down from the main trunk portion 21a in the direction of gravity. The discharge branch portion 224 is also called a hanging portion. The discharge branch portion 224 is positioned so as to be hung from the main trunk portion 21a. The discharge branch portion 224 is also called a hanging portion.

[0057] The discharge branch portion 224 is positioned at an end of a branch portion group including a plurality of branch portions 21b. The discharge branch portion 224 is located near one axial end of the pressure accumulator vessel 21. The discharge branch portion 224 essentially forms the end portion of the pressure accumulator vessel 21. The discharge branch portion 224 provides a bubble arrival suppression means for suppressing the amount of bubbles that reach the filtering member 23a while the engine 2 is operating.

[0058] The discharge branch portion 224 has a cylindrical shape. The discharge branch portion 224 is provided by a pipe corresponding to one end of the main trunk portion 21a. Due to its cylindrical shape, the discharge branch portion 224 defines a central axis CX224. The central axis CX224 coincides with the central axis of the pressure control valve 22. The central axis CX224 coincides with the central axis of the filter 23. The central axes of the pressure control valve 22 and the filter 23 coincide with each other. In the drawing, the central axis CX224 is shown by a dashed line.

[0059] The central axis CX224 intersects with the central axis CX21. The intersecting relationship between the central axis CX224 and the central axis CX21 is formed on the XY plane in the figure. The central axis CX224 and the central axis CX21 may be spaced apart by a predetermined distance in the Z-axis direction. In other words, the intersecting relationship is formed on a vertical cross section viewed from the horizontal direction. In the example shown in the figure, the central axis CX224 is perpendicular to the central axis CX21.

[0060] The pressure accumulator vessel 21 has an upper end 21U and an upper surface 21UW in the main trunk 21a. Because the main trunk 21a is disposed horizontally, the upper end 21U extends along the upper surface 21UW. Furthermore, the pressure accumulator vessel 21 has a lower end 21L at the discharge branch portion 224.

[0061] The entire filtering member 23a of the filter 23 is positioned inside the pressure accumulation chamber 21v in the discharge branch portion 224. A gap large enough to allow air bubbles to rise by their own buoyancy is formed between the inner surface of the discharge branch portion 224 and the filtering member 23a.

[0062] In this embodiment, the discharge branch portion 224 provides a retention suppression portion. In this embodiment, the discharge branch portion 224 provides a downward installation portion. In this embodiment, too, air bubbles rise in a direction away from the filter 23 around the filter 23 and in the accumulator chamber 21v located above the filter 23. In particular, air bubbles rise in a direction away from the filtration member 23a around the filtration member 23a and in the accumulator chamber 21v located above the filtration member 23a. As a result, the amount of air bubbles reaching the filtration member 23a of the filter 23 while the engine 2 is operating is suppressed. In this embodiment, too, problems caused by air bubbles reaching the exhaust system are suppressed.

[0063] Furthermore, in this embodiment, the angle of the central axis CX21 defined by the main trunk 21a relative to the horizontal can be set within a relatively wide range, including zero. This allows the main trunk 21a to be positioned at an angle that meets the requirements of the engine 2. Moreover, the discharge branch portion 224, which is provided so as to be suspended from the main trunk 21a, makes it possible to suppress problems caused by air bubbles reaching the discharge system.

[0064] Third embodiment This embodiment is a modification of the previous embodiment. In the previous embodiment, the discharge branch 224 hangs down from the main trunk 21a. Instead, in this embodiment, the discharge branch 224 is slightly inclined with respect to the direction of gravity.

[0065] FIG. 5 is a cross-sectional view showing a pressure accumulator 5 of a third embodiment. In FIG. 5, the discharge branch portion 324 is inclined with respect to the gravity direction GD on the XY plane. In this embodiment, the discharge branch portion 324 also extends downward in the gravity direction relative to the main trunk portion 21a. The discharge branch portion 324 is positioned so as to be suspended from the main trunk portion 21a. The discharge branch portion 324 has a cylindrical shape. Due to its cylindrical shape, the discharge branch portion 324 defines a central axis CX324. The central axis CX324 coincides with the central axis of the pressure control valve 22. The central axis CX324 coincides with the central axis of the filter 23. The central axes of the pressure control valve 22 and the filter 23 coincide with each other. In the figure, the central axis CX324 is indicated by a dashed line. The discharge branch portion 324 provides a bubble reaching suppression means for suppressing the amount of bubbles reaching the filtering member 23a while the engine 2 is operating.

[0066] The central axis CX324 is inclined at an inclination angle HA324 with respect to the direction of gravity GD. The inclination angle HA324 can be set within a range of less than ±90 degrees, including zero (0°≦HA324<±90°).

[0067] In this embodiment, the discharge branch 324 provides the retention suppression portion. In this embodiment, the discharge branch 324 provides the lower installation portion. In this embodiment, the same effects as in the preceding embodiment can be obtained.

[0068] Fourth embodiment This embodiment is a modification of the previous embodiment. In the previous embodiment, the discharge branch 224 hangs down from the main trunk 21a. Instead, in this embodiment, the discharge branch 224 is slightly inclined with respect to the direction of gravity.

[0069] FIG. 6 is a cross-sectional view showing the pressure accumulator 5 of the fourth embodiment. In FIG. 6, the discharge branch portion 424 is inclined with respect to the gravity direction GD in the YZ plane. In this embodiment, the discharge branch portion 424 also extends downward in the gravity direction relative to the main trunk portion 21a. The discharge branch portion 424 is positioned so as to be suspended from the main trunk portion 21a. The discharge branch portion 424 has a cylindrical shape. Due to its cylindrical shape, the discharge branch portion 424 defines a central axis CX424. The discharge branch portion 424 provides a bubble reaching suppression means that suppresses the amount of bubbles that reach the filtering member 23a while the engine 2 is operating.

[0070] The central axis CX424 is inclined at an inclination angle HA424 with respect to the direction of gravity GD. The inclination angle HA424 can be set within a range of less than ±90 degrees, including zero (0°≦HA424<±90°).

[0071] In this embodiment, the discharge branch 424 provides a retention suppression portion. In this embodiment, the discharge branch 424 provides a lower installation portion. In this embodiment, the same effects as in the preceding embodiment can be obtained.

[0072] As can be understood from the preceding third and fourth embodiments, the discharge branches 324, 424 extend downward in the direction of gravity relative to the main trunk 21a. The discharge branches 324, 424 can be arranged to be inclined in various directions relative to the direction of gravity GD.

[0073] Fifth embodiment This embodiment is a modification based on the preceding embodiment. In the preceding embodiment, the amount of bubbles reaching the exhaust system is suppressed by the shape of the pressure accumulator vessel 21. Instead, in this embodiment, the behavior of the fuel supply system 1 is controlled by the control device 6 to suppress the amount of bubbles reaching the exhaust system while the engine 2 is operating.

[0074] In this embodiment, the pressure accumulator 5 is disposed so that the central axis CX21 extends horizontally, as shown in FIG. 1 . Therefore, the fuel supply system 1 of this embodiment includes a pressure accumulator 5 that does not include a retention suppression unit and the control device 6 of this embodiment. The pressure accumulator 5 may have the structure of another embodiment that includes a retention suppression unit. In this case, the fuel supply system 1 of this embodiment includes the pressure accumulator 5 of another embodiment disclosed in this specification and the control device 6 of this embodiment.

[0075] FIG. 7 shows a flowchart illustrating the control process of the control device 6. The control device 6 controls the fuel supply system 1 when power is supplied. The control device 6 is activated as an electric circuit when power is supplied. The control device 6 repeatedly executes a circuit and a control process 560 according to a predetermined program while power is being supplied. Furthermore, the control device 6 is programmed to execute bubble suppression controls 562 and 563 that suppress the amount of bubbles reaching the exhaust system when the control device 6 is first started after fuel is introduced into the fuel system 3. When the control device 6 is not first started, the control device 6 is programmed to execute normal operation controls 564 and 565 that start the engine 2 and operate the engine 2.

[0076] When the high-pressure pump 15 flows a large amount of fuel during the first operation of the fuel system 3 after fuel is introduced into the fuel system 3, it is assumed that a large amount of air bubbles will reach the filter 23. This is because it is assumed that air bubbles remain in multiple locations in the fuel system 3 immediately after fuel is introduced into the fuel system 3. Several cases can be assumed for when fuel is introduced into the fuel system 3. One is immediately after the fuel supply system 1 and the engine 2 are assembled. Another is after maintenance or repair work has been performed on the fuel supply system 1. When the control device 6 is first activated after fuel is introduced into the fuel system 3, if the engine 2 is started and a large amount of fuel is flowed, it is assumed that a large amount of air bubbles will reach the filter 23. In this case, there is a concern that a malfunction will occur due to air bubbles reaching the filter 23. Therefore, in this embodiment, air bubble suppression control is executed during the first activation of the control device 6 after fuel is introduced into the fuel system 3 of the fuel supply system 1.

[0077] In step 561, the control device 6 determines whether or not this is the first startup of the control device 6 after fuel is introduced into the fuel line 3 of the fuel supply system 1. If it is the first startup, the process branches to YES from step 561. If it is not the first startup, the process branches to NO from step 561.

[0078] Step 561 determines the conditions under which defects caused by air bubbles are likely to occur. Only when the conditions under which defects caused by air bubbles are likely to occur are satisfied, is bubble suppression control, which will be described later, executed. Step 561 provides a condition determination unit that determines whether the conditions under which defects caused by air bubbles are likely to occur are satisfied. By providing step 561, opportunities for executing bubble suppression control, which will be described later, are reduced. This makes it possible to suppress defects caused by bubble suppression control. For example, it is possible to avoid the wait time required to execute bubble suppression control.

[0079] If the flow branches to YES in step 561, the control device 6 executes the control of step 562. The control device 6 executes bubble suppression control in step 562. In step 562, the control device 6 rotates the high-pressure pump 15 at a low rotation speed. The control device 6 rotates the motor 33 at a low rotation speed. If the high-pressure pump 15 is directly connected to the engine 2, the control device 6 rotates the starter motor of the engine 2 to rotate the high-pressure pump 15 at a low rotation speed. The bubble suppression control is also called air bleeding operation control.

[0080] The low rotation speed is a rotation speed at which fuel can be fed into the pressure accumulator 5. The low rotation speed is a rotation speed that causes a flow of fuel in the pressure accumulator container 21. However, the low rotation speed only causes a weak flow of fuel in the pressure accumulator container 21. The low rotation speed does not cause a strong flow of fuel in the pressure accumulator container 21. A strong flow level is a level that pushes a large amount of air bubbles toward the filter 23. The low rotation speed is a rotation speed that causes air bubbles in the fuel system of the fuel supply system 1 to flow slowly and gradually. In other words, the low rotation speed is a rotation speed that causes a flow of fuel in the pressure accumulator container 21 through the filter 23 toward the pressure control valve 22 during a preliminary period before the engine 2 is operated. Here, in order to open the pressure control valve 22, the movable valve element 22h may be forcibly opened from the outside. The low rotation speed is a rotation speed that suppresses the amount of air bubbles that reach the filter 23 during the operation of the engine 2 by preliminarily flowing air bubbles before the operation of the engine 2.

[0081] The low-speed rotation speed is a rotation speed that will not start the engine 2. The low-speed rotation speed is lower than the starting rotation speed that can start the engine 2. The low-speed rotation speed can be set to 15% or less of the maximum rotation speed of the high-pressure pump 15. The low-speed rotation speed can be set within a range of 15% ± 10% of the maximum rotation speed of the high-pressure pump 15. The low-speed rotation speed may be set, for example, within a range of 50 RPM or more and 800 RPM or less. The low-speed rotation speed may more desirably be set within a range of 100 RPM or more and 500 RPM or less.

[0082] In step 563, the control device 6 determines whether the completion condition for the bubble suppression control has been satisfied. If the bubble suppression control has not been completed, the process branches to NO from step 563. In this case, the process repeats step 562. As a result, the bubble suppression control continues. The bubble suppression control is desirably performed for a predetermined period of time. The predetermined period is desirably set to be longer than the period of time it takes for the fuel to circulate through all of the interior of the fuel system 3. The predetermined period may be determined by the duration of the bubble suppression control. In this case, in step 563, it is determined whether the predetermined duration has elapsed. The predetermined period may also be determined by the fuel flow rate in the fuel system 3. In this case, in step 563, it is determined, for example, whether the flow rate of the fuel in the return passage 19 has reached all of the internal capacity of the fuel system 3.

[0083] The processing in step 562 and step 563 is executed by the processor of the control device 6. The processor and the processing in steps 562 and 563 that cause the processor to function provide an air bubble reaching suppression means that suppresses the amount of air bubbles that reach the filtering member 23a while the engine 2 is operating.

[0084] If the bubble suppression control has been completed, the process branches to YES from step 563. In this case, the control device 6 ends the process. In this case, the control device 6 may proceed to steps 564 and 565, which will be described later.

[0085] If the process branches to NO in step 561, the control device 6 executes the control of step 564. In step 564, the control device 6 executes start control to start the engine 2. In step 564, the control device 6 rotates the high-pressure pump 15 at a rotation speed for starting the engine 2. In step 564, the control device 6 rotates the motor 33 to rotate the high-pressure pump 15 at the starting rotation speed. If the high-pressure pump 15 is directly connected to the engine 2, the control device 6 rotates the starter motor of the engine 2 to rotate the high-pressure pump 15 at the starting rotation speed. When the high-pressure pump 15 rotates at the starting rotation speed, the starter motor rotates the engine 2 at the cranking rotation speed required for starting. The starting rotation speed in step 564 is higher than the low-speed rotation speed in step 562. Once the engine 2 is started by the engine start control in step 564, the process proceeds to step 565.

[0086] In step 564, the control device 6 executes operation control to continuously operate the engine 2. This control of the engine 2 is called normal operation control. When the operation of the engine 2 eventually ends, the control device 6 ends the processing.

[0087] In this embodiment, the control device 6 can selectively execute both the bubble suppression control and the normal operation control. Alternatively, the control device 6 may be a device that executes only the bubble suppression control. For example, the control device 6 may be provided by a dedicated device installed in a factory or a maintenance workshop. In this case, the control device 6 executes the bubble suppression control after fuel is introduced into the fuel system including the pressure accumulator vessel 21 and before the engine 2 is started.

[0088] In this embodiment, the fuel supply system 1 includes a control device 6 that controls the high-pressure pump 15. The control device 6 includes at least one processor and executes a bubble suppression control 562 using the processor. The bubble suppression control 562 operates the high-pressure pump 15 to discharge bubbles from the fuel system after fuel is introduced into the fuel system including the pressure accumulator 21 and before the engine 2 is started. The timing indicating "before the engine 2 is started" can be, for example, "the initial start-up of the control device 6" or "the initial start-up of the engine 2." In the bubble suppression control 562, the control device 6 operates the high-pressure pump 15 at a low rotation speed that is lower than the starting rotation speed for starting the engine 2. That is, the bubble suppression control 562 is executed before the engine 2 is started. This reduces the amount of bubbles that reach the filter member 23a during the operation of the engine 2. As a result, problems caused by bubbles reaching the filter 23 and the pressure control valve 22 are reduced.

[0089] According to this embodiment, it is possible to prevent a large amount of air bubbles from reaching the filter 23. Therefore, problems caused by a large amount of air bubbles reaching the filter 23 are prevented.

[0090] Sixth embodiment This embodiment is a modification based on the preceding embodiment. In the preceding embodiment, air bubbles are prevented from reaching the filter 23. Instead, in this embodiment, the discharge of air bubbles is promoted to prevent a large amount of air bubbles from reaching the filter 23.

[0091] FIG. 8 is a cross-sectional view showing a pressure accumulator 5 of a sixth embodiment. In FIG. 8, the pressure accumulator 5 includes a spacer 625. The spacer 625 is an annular member. The spacer 625 is arranged so as to surround the radial outside of the filter 23. The spacer 625 provides a member that fills corners in the pressure accumulator chamber 21v of the pressure accumulator vessel 21 where air bubbles are likely to accumulate. The spacer 625 suppresses the collection and bonding of air bubbles in the pressure accumulator chamber 21v. The spacer 625 suppresses the retention of air bubbles inside the pressure accumulator vessel 21. The spacer 625 also serves as a guide member that guides the flow of fuel and the flow of air bubbles in the chamber 21v.

[0092] The spacer 625 provides a slope 625S. The slope 625S is shaped to gradually approach from the upper surface 21UW of the pressure accumulator vessel 21 toward the outer surface (filtration surface) of the filter 23. The slope 625S is shaped to gradually approach from the inner surface of the pressure accumulator vessel 21 toward the outer surface (filtration surface) of the filter 23. The slope 625S is a tapered surface. The slope 625S approaches from the upper surface 21UW toward the outer surface of the filter 23 along the fuel flow direction from the pressure accumulator chamber 21v toward the pressure control valve 22. The slope 625S is also called a guide surface.

[0093] In this embodiment, bubbles are prevented from accumulating in the pressure accumulator chamber 21v. Therefore, the bubbles in the pressure accumulator chamber 21v do not gather, combine, and grow large. Furthermore, the bubbles flow along the slope 625S toward the filter 23 and reach the outer surface of the filter 23. The bubbles reach the outer surface of the filter 23 in the form of small bubbles without growing large, and pass through the filter 23. Therefore, the slope 625S encourages small bubbles to reach the filter 23, thereby providing a bubble arrival suppression means that suppresses the amount of bubbles that reach the filtering member 23a while the engine 2 is operating.

[0094] From another perspective, the inclined surface 625S allows air bubbles to rise in the fuel. By allowing the air bubbles to rise, the inclined surface 625S may move the air bubbles away from the filter 23. Therefore, the inclined surface 625S provides a means for suppressing air bubbles from reaching the filtering member 23a by moving the air bubbles away from the filter 23.

[0095] In the illustrated embodiment, the spacer 625 is provided as a separate member from both the pressure accumulator vessel 21 and the valve seat member 22b. Alternatively, the spacer 625 may be provided integrally with the pressure accumulator vessel 21 using a continuous material. Furthermore, the spacer 625 may be provided integrally with the valve seat member 22b using a continuous material. In addition, the spacer 625 may be provided integrally with the non-filtering member 23b of the filter 23 using a continuous material.

[0096] In this embodiment, the slope 625S provides a retention prevention portion. In this embodiment, the air bubbles in the pressure accumulator chamber 21v pass through the filter 23 in the form of small bubbles, without gathering and combining within the pressure accumulator chamber 21v to grow larger. As a result, the air bubbles pass through the filter 23 and the pressure control valve 22, and are discharged from the discharge passage 22k to the return passage 19. In this embodiment, problems caused by large air bubbles reaching the filter 23 are suppressed.

[0097] Seventh embodiment This embodiment is a modification based on the preceding embodiment.

[0098] Fig. 9 is a cross-sectional view showing a pressure accumulator 5 of the seventh embodiment. In Fig. 9, a filter 723 is obtained by changing the position of the filter 23 of the preceding embodiment. The filter 723 is positioned in the upper half of the pressure accumulation chamber 21v in the direction of gravity. The central axis CX23 of the filter 723 is positioned higher in the direction of gravity than the central axis CX21 of the pressure accumulator vessel 21. As a result, the distance between the filter 723 and the upper surface 21UW is shorter than the distance between the filter 23 and the upper surface 21UW of the preceding embodiment.

[0099] In this embodiment, the retention prevention unit is provided by a filter 723 positioned above the central axis CX21. The filter 723 allows fuel in the upper half of the pressure accumulator chamber 21v to pass more easily than fuel in the lower half of the pressure accumulator chamber 21v. At the same time, the filter 723 allows air bubbles floating in the upper half of the pressure accumulator chamber 21v to pass through. In other words, the filter 723 allows relatively small air bubbles to pass through the upper half of the pressure accumulator chamber 21v. The filter 723, characterized by its installation position, provides air bubble arrival prevention means that reduces the amount of air bubbles that reach the filtering member 23a while the engine 2 is operating.

[0100] In this embodiment, the air bubbles in the pressure accumulation chamber 21v do not gather, combine, and grow large within the pressure accumulation chamber 21v. The air bubbles pass through the filter 723 in a small state. As a result, the air bubbles pass through the filter 723 and the pressure control valve 22, and are discharged from the discharge passage 22k to the return passage 19. In this embodiment, problems caused by large air bubbles reaching the filter 723 are suppressed.

[0101] Eighth embodiment This embodiment is a modification based on the preceding embodiment. In the preceding embodiment, the discharge of air bubbles is promoted to prevent a large amount of air bubbles from reaching the filter 23. Instead, in this embodiment, the air bubbles are trapped to prevent a large amount of air bubbles from reaching the filter 23.

[0102] Fig. 10 is a cross-sectional view showing a pressure accumulator 5 of an eighth embodiment. In Fig. 10, a filter 823 is obtained by changing the position of the filter 23 of the preceding embodiment. The filter 823 is positioned in the upper half of the pressure accumulation chamber 21v in the direction of gravity. The central axis CX23 of the filter 823 is positioned lower in the direction of gravity than the central axis CX21 of the pressure accumulator vessel 21. As a result, the distance between the filter 823 and the upper surface 21UW is longer than the distance between the filter 23 and the upper surface 21UW of the preceding embodiment.

[0103] The filter 823 allows fuel in the lower half of the pressure accumulator chamber 21v to pass through more easily than fuel in the upper half of the pressure accumulator chamber 21v. As a result, air bubbles tend to accumulate in the upper part of the pressure accumulator chamber 21v. The corner space 826 or a member defining the corner space 826 provides air bubble arrival suppression means for suppressing the amount of air bubbles that reach the filtering member 23a while the engine 2 is operating.

[0104] A relatively large corner space 826 is formed between the upper surface 21UW of the pressure accumulator chamber 21v and the end surface 22d of the valve seat member 22b. The relatively large corner space 826 results from the central axis CX23 of the filter 823 being offset downward. The corner space 826 actively captures air bubbles. The air bubbles remain in the corner space 826, gather, combine, and grow. These air bubbles gradually dissolve in the fuel and gradually flow out without reaching the filter 23.

[0105] In this embodiment, the corner space 826 provides a bubble capture section provided in the pressure accumulator vessel 21. The corner space 826, or the member that defines the corner space 826, can also be said to provide a retention suppression section. The bubble capture section captures air bubbles before they reach the filtering member 23a. As a result, the bubble capture section reduces the amount of bubbles that reach the filtering member 23a while the engine 2 is operating. According to this embodiment, the corner space 826 captures air bubbles before they reach the filtering member 23a. As a result, the amount of bubbles that reach the filtering member 23a while the engine 2 is operating is reduced. As a result, problems caused by bubbles reaching the filter 823 and the pressure control valve 22 are reduced.

[0106] Ninth embodiment This embodiment is a modification based on the preceding embodiment.

[0107] Fig. 11 is a cross-sectional view showing a pressure accumulator 5 of a ninth embodiment. In Fig. 11, a valve seat member 922b has an elongated cylindrical shape that houses the filter 23. The valve seat member 922b has an end face 922d. The end face 922d is located on the tip side, axially away from the axial range of the filtering member 23a of the filter 23. In this embodiment, the end face 922d also forms a corner space 926.

[0108] The corner space 926 is not located radially outward from the filtering member 23a. The corner space 926 is located axially away from the axial range of the filtering member 23a. The corner space 926 is located upstream of the filter 23 in the direction of fuel flow from the accumulator chamber 21v toward the pressure control valve 22. The corner space 926 is located axially upstream from the axial range of the filtering member 23a. Therefore, air bubbles are trapped in the corner space 926 at a position away from the filtering member 23a. The corner space 926 or a member defining the corner space 926 provides air bubble arrival suppression means that suppresses the amount of air bubbles that reach the filtering member 23a while the engine 2 is operating.

[0109] In this embodiment, the corner space 926 provides a bubble trap. It can also be said that the corner space 926 or the member defining the corner space 926 provides a retention suppression portion. In this embodiment as well, problems caused by bubbles reaching the filter 823 and the pressure control valve 22 are suppressed.

[0110] Tenth embodiment This embodiment is a modification based on the preceding embodiment.

[0111] Fig. 12 is a cross-sectional view showing a pressure accumulator 5 of a tenth embodiment. In Fig. 12, the filter A23 has a non-filtration member A23b. The non-filtration member A23b is longer than the non-filtration member 23b of the filter 23. The non-filtration member A23b forms a corner space A26 between the inner surface of the pressure accumulator vessel 21, the end face 22d, and the outer peripheral surface of the non-filtration member A23b.

[0112] The corner space A26 is not located radially outward from the filtering member 23a. The corner space A26 is located axially away from the axial range of the filtering member 23a. The corner space A26 is located downstream of the filter A23 in the direction of fuel flow from the accumulator chamber 21v toward the pressure control valve 22. The corner space A26 is located axially downstream from the axial range of the filtering member 23a. Therefore, bubbles trapped in the corner space A26 are unlikely to return from the corner space A26 to the filtering member 23a. Therefore, bubbles trapped in the corner space A26 are unlikely to reach the filtering member 23a. The corner space A26 or a member defining the corner space A26 provides a bubble arrival suppression means that suppresses the amount of bubbles that reach the filtering member 23a while the engine 2 is operating.

[0113] In this embodiment, the corner space A26 provides a bubble trap. The corner space A26 or the member defining the corner space A26 can also be said to provide a retention suppression portion. This embodiment also suppresses problems caused by bubbles reaching the filter A23 and the pressure control valve 22.

[0114] Other embodiments The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and variations thereon by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0115] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims.

[0116] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0117] (Technical thought 1) a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and that is fluidly connected to a plurality of injectors (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filtering member (23a) for filtering fuel discharged from the pressure accumulator; A fuel accumulator comprising air bubble reaching suppression means (21L, 224, 324, 424, 562, 625S, 723, 826, 926, A26) for suppressing the amount of air bubbles reaching the filtering member during operation of the internal combustion engine.

[0118] (Technical thought 2) a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and that is fluidly connected to a plurality of injectors (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filtering member (23a) for filtering fuel discharged from the pressure accumulator; A fuel accumulator device comprising a lower installation portion (21L, 224, 324, 424) that positions the pressure control valve and the filter below the pressure accumulator vessel in the direction of gravity.

[0119] (Technical Thought 3) The pressure accumulator vessel is a central axis (CX21) extending in an axial direction and inclined at an inclination angle (SA21) with respect to the horizontal; The fuel accumulator according to Technical Concept 2 has a lower end (21L) of the pressure accumulator vessel that is positioned downward in the direction of gravity due to the inclination angle and provides the lower installation portion.

[0120] (Technical Thought 4) The pressure accumulator vessel is a main trunk portion (21a) having a central axis (CX21) extending in the axial direction; The fuel accumulator according to Technical Idea 2 or 3, further comprising a discharge branch portion (224, 324, 424) extending downward from the main trunk portion in the direction of gravity and providing the downward installation portion.

[0121] (Technical Thought 5) a high-pressure pump (15) for pressurizing fuel to injection pressure; a pressure accumulator vessel (21) defining a pressure accumulator chamber into which fuel pressurized to an injection pressure is introduced, the pressure accumulator vessel (21) being fluidly connected to a plurality of injectors (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filtering member (23a) for filtering fuel discharged from the pressure accumulator; a control device (6) for controlling the high-pressure pump, the control device including at least one processor, the control device (6) executing, by the processor, bubble suppression control (562) for operating the high-pressure pump so as to discharge bubbles from the fuel system after fuel is introduced into the fuel system including the pressure accumulator vessel and before the internal combustion engine is operated.

[0122] (Technical Thought 6) The fuel supply system according to Technical Idea 5, wherein the control device operates the high-pressure pump at a low rotation speed that is lower than a starting rotation speed for starting the internal combustion engine during the bubble suppression control.

[0123] (Technical Thought 7) a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and that is fluidly connected to a plurality of injectors (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filtering member (23a) for filtering fuel discharged from the pressure accumulator; A fuel accumulator device comprising: a retention suppression section (21S, 625S, 723) provided in the pressure accumulator vessel, which suppresses retention of bubbles upstream of the filter in the direction of fuel flow toward the pressure control valve in the pressure accumulator chamber.

[0124] (Technical Thought 8) The pressure accumulator vessel has an upper surface (21UW) that defines the pressure accumulator chamber, The fuel accumulator according to Technical Concept 7, wherein the retention prevention portion is provided by an inclined surface (21S, 625S) that guides air bubbles from the upper surface to the filtering member.

[0125] (Technical Thought 9) The pressure accumulator vessel has a central axis (CX21) extending in the axial direction, The fuel accumulator according to Technical Idea 7 or 8, wherein the retention suppression portion is provided by the filter (723) positioned above the central axis.

[0126] (Technical Thought 10) a pressure accumulator vessel (21) defining a pressure accumulator chamber into which fuel pressurized to an injection pressure is introduced, the pressure accumulator vessel (21) being fluidly connected to a plurality of injectors (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filtering member (23a) for filtering fuel discharged from the pressure accumulator; a bubble capturing section (826, 926, A26) provided in the pressure accumulator vessel, capturing bubbles before they reach the filtering member and reducing the amount of bubbles that reach the filtering member while the internal combustion engine is in operation.

[0127] (Technical Thought 11) The fuel accumulator according to Technical Idea 1, wherein the bubble reaching suppression means includes a lower installation portion (21L, 224, 324, 424) that positions the pressure control valve and the filter below the pressure accumulator vessel in the direction of gravity.

[0128] (Technical Thought 12) The fuel accumulator device according to Technical Idea 1 or Technical Idea 11, wherein the bubble arrival suppression means is provided in the accumulator vessel and includes a retention suppression section (21S, 625S, 723) that suppresses retention of bubbles upstream of the filter in the direction of fuel flow toward the pressure control valve in the accumulator chamber.

[0129] (Technical Thought 13) The pressure accumulator vessel has an upper surface (21UW) that defines the pressure accumulator chamber, The fuel accumulator according to Technical Idea 12, wherein the retention prevention portion is provided by an inclined surface (21S, 625S) that guides air bubbles from the upper surface to the filtering member.

[0130] (Technical Thought 14) The pressure accumulator vessel has a central axis (CX21) extending in the axial direction, The fuel accumulator according to Technical Idea 12 or 13, wherein the retention suppression unit is provided by the filter (723) positioned above the central axis.

[0131] (Technical Thought 15) The fuel accumulator according to any one of Technical Ideas 1, 11, 12, 13, and 14, wherein the bubble arrival suppression means is provided in the accumulator vessel and includes a bubble capture section (826, 926, A26) that captures bubbles before they reach the filtering element and suppresses the amount of bubbles that reach the filtering element during the operation of the internal combustion engine.

[0132] (Technical Thought 16) A fuel pressure accumulator according to any one of Technical Idea 1, Technical Idea 11, Technical Idea 12, Technical Idea 13, Technical Idea 14, and Technical Idea 15; a high-pressure pump (15) for pressurizing fuel to an injection pressure; The bubble arrival suppression means is a control device that controls the high-pressure pump, and includes at least one processor. The fuel supply system is equipped with a control device (6) that uses the processor to execute bubble suppression control (562) to operate the high-pressure pump so as to discharge bubbles from the fuel system after fuel is introduced into the fuel system including the pressure accumulator vessel and before the internal combustion engine is operated.

[0133] (Technical Thought 17) The fuel supply system according to Technical Idea 16, wherein the control device operates the high-pressure pump at a low rotation speed that is lower than a starting rotation speed for starting the internal combustion engine during the bubble suppression control. [Explanation of symbols]

[0134] 1 fuel supply system, 2 engine, 3 fuel system, 4 fuel supply device, 5 fuel pressure storage device, 6 control device, 15 high pressure pump, 18 injector, 19 return passage, 21 pressure accumulator vessel, 22 pressure control valve, 23, 723, 823, A23 filters.

Claims

1. a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and that is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filter member (23a) for filtering fuel discharged from the pressure accumulator; A fuel accumulator comprising: air bubble reaching suppression means (21L, 224, 324, 424, 562, 625S, 723, 826, 926, A26) for suppressing the amount of air bubbles reaching the filtering member while the internal combustion engine is in operation.

2. a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and that is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filter member (23a) for filtering fuel discharged from the pressure accumulator; A fuel accumulator comprising a lower installation portion (21L, 224, 324, 424) that positions the pressure control valve and the filter below the pressure accumulator vessel in the direction of gravity.

3. The pressure accumulator vessel is a central axis (CX21) extending in an axial direction and inclined at an inclination angle (SA21) with respect to the horizontal; 3. The fuel accumulator according to claim 2, further comprising a lower end (21L) of the pressure accumulator vessel that is positioned lower in the direction of gravity due to the inclination angle and provides the lower installation portion.

4. The pressure accumulator vessel is A main trunk (21a) having a central axis (CX21) extending in the axial direction; 4. The fuel accumulator according to claim 2, further comprising a discharge branch portion (224, 324, 424) extending downward from the main trunk portion in the direction of gravity and providing the lower installation portion.

5. a high-pressure pump (15) for pressurizing fuel to injection pressure; a pressure accumulator vessel (21) defining a pressure accumulator chamber into which fuel pressurized to an injection pressure is introduced, the pressure accumulator vessel (21) being fluidly connected to a plurality of injectors (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filter member (23a) for filtering fuel discharged from the pressure accumulator; a control device (6) for controlling the high-pressure pump, the control device including at least one processor, the control device (6) executing, by the processor, bubble suppression control (562) for operating the high-pressure pump so as to discharge bubbles from the fuel system after fuel is introduced into a fuel system including the pressure accumulator vessel and before operation of the internal combustion engine.

6. 6. The fuel supply system according to claim 5, wherein the control device, during the bubble suppression control, operates the high-pressure pump at a low rotation speed that is lower than a starting rotation speed for starting the internal combustion engine.

7. a pressure accumulator vessel (21) that defines a pressure accumulator chamber (21v) into which fuel pressurized to an injection pressure is introduced and that is fluidly connected to a plurality of injection devices (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filter member (23a) for filtering fuel discharged from the pressure accumulator; a retention suppression section (21S, 625S, 723) provided in the pressure accumulator vessel to suppress retention of air bubbles upstream of the filter in the direction of fuel flow toward the pressure control valve in the pressure accumulator chamber.

8. The pressure accumulator vessel has an upper surface (21UW) that defines the pressure accumulator chamber, 8. The fuel accumulator according to claim 7, wherein the retention prevention portion is provided by an inclined surface (21S, 625S) that guides air bubbles from the upper surface to the filtering member.

9. The pressure accumulator vessel has a central axis (CX21) extending in the axial direction, 9. The fuel accumulator according to claim 7, wherein the retention suppression portion is provided by the filter (723) positioned above the central axis.

10. a pressure accumulator vessel (21) defining a pressure accumulator chamber into which fuel pressurized to an injection pressure is introduced, the pressure accumulator vessel (21) being fluidly connected to a plurality of injectors (18) that supply fuel to an internal combustion engine; a pressure control valve (22) provided in the pressure accumulator vessel, which opens in response to the fuel pressure in the pressure accumulator chamber and discharges fuel from the pressure accumulator chamber; a filter (23, 723, 823, A23) provided between the pressure accumulator and the pressure control valve and including a filter member (23a) for filtering fuel discharged from the pressure accumulator; a bubble capturing section (826, 926, A26) provided in the pressure accumulator vessel, capturing air bubbles before they reach the filtering member and reducing the amount of air bubbles that reach the filtering member while the internal combustion engine is in operation.

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