Fuel pump

Abstract

A fuel pump includes a damper, a suction valve chamber, a pressurization chamber, a pressure reduction valve chamber, a pressure reduction valve mechanism, and a shock wave absorbing portion. The shock wave absorbing portion is provided in the pressure reduction valve chamber and is disposed opposite the pressure reduction valve holder on the downstream side in the direction in which the pressure reduction valve holder moves when the pressure reduction valve mechanism is released.

Description

Technical Field

[0001] The present invention relates to a fuel pump for an internal combustion engine of an automobile. Background Art

[0002] In direct injection engines (internal combustion engines) such as automobiles, which inject fuel directly into combustion chambers, high-pressure fuel pumps are widely used to increase the fuel pressure.

[0003] Patent Document 1 describes a technology for a high-pressure fuel pump having a housing, in which a pressure limiting valve is disposed in a hole in the housing, and the hole opens into a supply volume chamber of a low-pressure supply portion.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2018-523778 Summary of the Invention

[0007] Technical problem to be solved by the invention

[0008] Furthermore, in the technology described in Patent Document 1, to ensure the flow rate of fuel supplied to the pressurized chamber, the pressure-reducing valve chamber, which houses the pressure-reducing valve mechanism, is directly connected to the intake valve chamber. However, with the recent increase in fuel pump pressure, the pressure required to release the pressure-reducing valve mechanism has increased, and the shock wave generated when the pressure-reducing valve mechanism is released has also increased. As a result, in the technology described in Patent Document 1, the shock wave generated when the pressure-reducing valve mechanism is released could damage various components of the mechanism, such as the pressure pulsation reduction mechanism and the low-pressure piping, located upstream of the pressure-reducing valve mechanism.

[0009] An object of the present invention is to provide a fuel pump that can suppress damage to various mechanism components due to a shock wave generated when a relief valve mechanism is released, in view of the above-mentioned problems.

[0010] Technical solutions to problems

[0011] In order to solve the above-mentioned problems and achieve the purpose of the present invention, the fuel pump of the present invention includes: a damper, a suction valve chamber, a pressurizing chamber, a pressure reducing valve chamber, a pressure reducing valve mechanism and a shock wave absorbing unit. The suction valve chamber is connected to the damper via a suction passage. The pressurizing chamber is formed on the downstream side of the suction valve chamber. The pressure reducing valve chamber is formed on the downstream side of the pressurizing chamber. The pressure reducing valve mechanism is arranged in the pressure reducing valve chamber and has a pressure reducing valve retainer. The shock wave absorbing unit is arranged in the pressure reducing valve chamber and is arranged opposite to the pressure reducing valve retainer on the downstream side of the direction in which the pressure reducing valve retainer moves when the pressure reducing valve mechanism is released.

[0012] Effects of the Invention

[0013] According to the fuel pump having the above-described structure, it is possible to suppress damage to the various mechanism components due to the shock wave generated when the pressure reducing valve mechanism is released.

[0014] In addition, other problems, structures, and effects than those described above will become apparent from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an overall configuration diagram of a fuel supply system using a high-pressure fuel pump according to an embodiment of the present invention.

[0016] Figure 2 This is a longitudinal sectional view (part 1) of a high-pressure fuel pump according to an embodiment of the present invention.

[0017] Figure 3 This is a longitudinal sectional view (part 2) of a high-pressure fuel pump according to an embodiment of the present invention.

[0018] Figure 4 This is a horizontal cross-sectional view of a high-pressure fuel pump according to an embodiment of the present invention, as viewed from above.

[0019] Figure 5 This is a longitudinal sectional view (part 3) of a high-pressure fuel pump according to an embodiment of the present invention.

[0020] Figure 6 This is an enlarged cross-sectional view showing a pressure reducing valve mechanism of a high-pressure fuel pump according to one embodiment of the present invention.

[0021] 7 is a diagram showing a shock wave absorbing portion and a supply communication hole of a high-pressure fuel pump according to an embodiment of the present invention; Figure 7A This is a front view showing the shock wave absorbing portion and the supply connecting hole. Figure 7B It is a perspective view showing the shock wave absorbing portion and the supply communication hole.

[0022] 8 is a diagram showing another example of the supply communication hole of the high-pressure fuel pump according to one embodiment of the present invention; Figure 8A This is a front view showing the shock wave absorbing portion and the supply connecting hole. Figure 8B It is a perspective view showing the shock wave absorbing portion and the supply communication hole. DETAILED DESCRIPTION

[0023] 1. One embodiment of a high-pressure fuel pump

[0024] Hereinafter, a high-pressure fuel pump according to an embodiment of the present invention will be described.

[0025] [Fuel supply system]

[0026] First, a fuel supply system using the high-pressure fuel pump of this embodiment is used. Figure 1 Provide explanation.

[0027] Figure 1 1 is an overall configuration diagram of a fuel supply system using the high-pressure fuel pump of this embodiment.

[0028] like Figure 1 As shown, the fuel supply system includes a high-pressure fuel pump 100, an ECU (Engine Control Unit) 101, a fuel tank 103, a common rail 106, and a plurality of injectors 107. The components of the high-pressure fuel pump 100 are integrally assembled into a pump body 1.

[0029] The fuel in the fuel tank 103 is pumped by the feed pump 102 driven by a signal from the ECU 101. The pumped fuel is pressurized to an appropriate pressure by a pressure regulator (not shown) and delivered to the suction joint 5 (see FIG. 5 ) provided on the high-pressure fuel pump 100 via the low-pressure pipe 104. Figure 2 )'s low-pressure fuel intake port 51.

[0030] A high-pressure fuel pump 100 pressurizes the fuel supplied from a fuel tank 103 and delivers it to a common rail 106. Common rail 106 is equipped with multiple injectors 107 and a fuel pressure sensor 105. The multiple injectors 107 are installed to match the number of cylinders (combustion chambers) and inject fuel based on the drive current output from the ECU 101. The fuel supply system of this embodiment is a so-called direct injection engine system, in which the injectors 107 inject fuel directly into the cylinder chambers of the engine.

[0031] The fuel pressure sensor 105 outputs the detected pressure data to the ECU 101. The ECU 101 calculates the appropriate injected fuel amount (target injection length) and the appropriate fuel pressure (target fuel pressure) based on engine state information obtained from various sensors (e.g., crank angle, throttle opening, engine speed, fuel pressure, etc.).

[0032] The ECU 101 controls the driving of the high-pressure fuel pump 100 and the plurality of injectors 107 based on calculation results of the fuel pressure (target fuel pressure), etc. Specifically, the ECU 101 includes a pump control unit that controls the high-pressure fuel pump 100 and an injector control unit that controls the injectors 107 .

[0033] The high-pressure fuel pump 100 includes a plunger 2, a pressure pulsation reducing mechanism 9, an electromagnetic suction valve mechanism 3 as a capacity variable mechanism, and a pressure reducing valve mechanism 4 (see Figure 2) and the discharge valve mechanism 8. The fuel flowing in from the low-pressure fuel intake port 51 passes through the pressure pulsation reducing mechanism 9 and the intake passage 10b to reach the intake port 31b of the electromagnetic intake valve mechanism 3.

[0034] The fuel flowing into the electromagnetic suction valve mechanism 3 passes through the suction valve 32 and flows into the supply communication hole 1g formed in the pump body 1 (see Figure 2 ) and then flows into the pressurized chamber 11. The pump body 1 holds the plunger 2 slidably. The plunger 2 passes through the engine cam 91 (refer to Figure 2 ) is transmitted with power and performs reciprocating motion. One end of the plunger 2 is inserted into the pressurized chamber 11, so that the volume of the pressurized chamber 11 increases or decreases.

[0035] In the pressurizing chamber 11, fuel is drawn from the electromagnetic intake valve mechanism 3 during the plunger 2's downward stroke, and the fuel is pressurized during the plunger 2's upward stroke. When the fuel pressure in the pressurizing chamber 11 exceeds a set value, the discharge valve mechanism 8 opens, pumping the high-pressure fuel through the discharge passage 12a of the discharge joint 12 to the common rail 106. Fuel discharge from the high-pressure fuel pump 100 is controlled by the opening and closing of the electromagnetic intake valve mechanism 3. The opening and closing of the electromagnetic intake valve mechanism 3 is controlled by the ECU 101.

[0036] If abnormally high pressure occurs in the common rail 106 or the like due to a malfunction of the injector 107 or the like, and the pressure differential between the discharge passage 12a of the discharge joint 12 communicating with the common rail 106 and the pressurization chamber 11 exceeds the valve opening pressure (prescribed value) of the pressure reducing valve mechanism 4, the pressure reducing valve mechanism 4 opens. This allows the abnormally high-pressure fuel to pass through the pressure reducing valve mechanism 4 and return to the pressurization chamber 11. As a result, the piping of the common rail 106 and the like is protected.

[0037] [High-pressure fuel pump]

[0038] Next, the structure of the high-pressure fuel pump 100 is analyzed using Figures 2 to 5 Provide explanation.

[0039] Figure 2 This is a longitudinal sectional view (part 1) of the high-pressure fuel pump 100 as viewed along a cross section perpendicular to the horizontal direction. Figure 3 This is a longitudinal cross-sectional view (part 2) of the high-pressure fuel pump 100 taken along a cross section perpendicular to the horizontal direction. Figure 4 This is a horizontal cross-sectional view of the high-pressure fuel pump 100 viewed at a cross section perpendicular to the vertical direction. Figure 5 This is a longitudinal sectional view (part 3) of the high-pressure fuel pump 100 as viewed along a cross section perpendicular to the horizontal direction.

[0040] like Figures 2 to 5 As shown in FIG. 1 , the pump body 1 of the high-pressure fuel pump 100 is formed into a substantially cylindrical shape. Figure 2 and Figure 3As shown, the pump body 1 is internally provided with a first chamber 1a, a second chamber 1b, a third chamber 1c, a shock wave absorbing portion 1d, a supply communication hole 1g, and a suction valve chamber 30. Furthermore, the pump body 1 is in close contact with the fuel pump mounting portion 90 and is fixed thereto by a plurality of bolts (screws) not shown.

[0041] The first chamber 1a is a cylindrical space provided in the pump body 1. The centerline 1A of the first chamber 1a is aligned with the centerline of the pump body 1. One end of the plunger 2 is inserted into this first chamber 1a, and the plunger 2 reciprocates within the first chamber 1a. This first chamber 1a and one end of the plunger 2 form a pressurization chamber 11. Furthermore, the first chamber 1a communicates with the suction valve chamber 30 via a supply communication hole 1g, described later. A second chamber 1b, serving as a pressure reducing valve chamber, is formed downstream of the pressurization chamber 11.

[0042] The second chamber 1b is a cylindrical space provided in the pump body 1. The centerline of the second chamber 1b is perpendicular to the centerline of the first chamber 1a. A pressure-reducing valve mechanism 4, described later, is located in the second chamber 1b, forming a pressure-reducing valve chamber. Furthermore, the diameter of the second chamber 1b, serving as the pressure-reducing valve chamber, is smaller than that of the first chamber 1a.

[0043] Furthermore, the first chamber 1a and the second chamber 1b are connected via a circular communication hole 1e. The diameter of the communication hole 1e is the same as that of the first chamber 1a, extending one end of the first chamber 1a. The diameter of the communication hole 1e is larger than the outer diameter of the plunger 2. This prevents the plunger 2, which reciprocates within the pressurized chamber 11, from colliding with the area surrounding the communication hole 1e, improving the durability of the plunger 2.

[0044] Furthermore, the centerline of the communication hole 1e is perpendicular to the centerline of the second chamber 1b. This allows fuel that has passed through the pressure reducing valve mechanism 4 to efficiently pass through the communication hole 1e, without hindering improved pressure reduction performance. Furthermore, the shape of the pump body 1 can be reduced to a less complex shape, thereby improving the productivity of the pump body 1 and the high-pressure fuel pump 100.

[0045] like Figure 3 and Figure 5 As shown, the diameter of the communicating hole 1e is larger than that of the second chamber 1b. In a cross-section perpendicular to the centerline of the second chamber 1b, the communicating hole 1e has a tapered surface 1f whose diameter decreases as it approaches the second chamber 1b. This allows fuel that has passed through the pressure reducing valve mechanism 4 in the second chamber 1b to flow along the tapered surface 1f and smoothly return to the pressurized chamber 11.

[0046] The third chamber 1c is a cylindrical space provided in the pump body 1, connected to the other end of the first chamber 1a. The centerline of the third chamber 1c coincides with the centerline 1A of the first chamber 1a and the centerline of the pump body 1, and the diameter of the third chamber 1c is larger than that of the first chamber 1a. A cylinder 6 is located within the third chamber 1c to guide the reciprocating motion of the plunger 2. This allows the end face of the cylinder 6 to abut against the step between the first and third chambers 1a, preventing the cylinder 6 from shifting toward the first chamber 1a.

[0047] The barrel 6 is cylindrical and is pressed into the third chamber 1c of the pump body 1 on its outer circumference. One end of the barrel 6 abuts against the step between the first chamber 1a and the third chamber 1c, which serves as the top surface of the third chamber 1c. The plunger 2 slidably contacts the inner circumference of the barrel 6.

[0048] like Figure 2 As shown, an O-ring 93 is interposed between the fuel pump mounting portion 90 and the pump body 1. The O-ring 93 prevents engine oil from leaking out of the engine (internal combustion engine) through the gap between the fuel pump mounting portion 90 and the pump body 1.

[0049] A tappet 92 is provided at the lower end of the plunger 2. The tappet 92 converts the rotational motion of a cam 91 mounted on the engine's camshaft into vertical motion, which is then transmitted to the plunger 2. The plunger 2 is biased toward the cam 91 by a spring 16 via a retainer 15, pressing against the tappet 92. The plunger 2 reciprocates with the tappet 92, causing the volume of the pressurized chamber 11 to change.

[0050] A seal holder 17 is disposed between the barrel 6 and the retainer 15. The seal holder 17 is formed into a cylindrical shape into which the plunger 2 can be inserted. A subchamber 17a is formed at the upper end of the seal holder 17 on the barrel 6 side. Meanwhile, a plunger seal 18 is retained at the lower end of the seal holder 17 on the retainer 15 side.

[0051] The plunger seal 18 is in slidable contact with the outer periphery of the plunger 2. The plunger seal 18 seals the fuel in the auxiliary chamber 17a during the reciprocating motion of the plunger 2, preventing the fuel in the auxiliary chamber 17a from flowing into the engine. Furthermore, the plunger seal 18 prevents lubricating oil (including engine oil) that lubricates the sliding parts within the engine from flowing into the pump body 1.

[0052] exist Figure 2 In the embodiment of the present invention, the plunger 2 reciprocates in the vertical direction. When the plunger 2 descends, the volume of the pressurized chamber 11 increases, and when the plunger 2 ascends, the volume of the pressurized chamber 11 decreases. In other words, the plunger 2 is configured to reciprocate in directions that increase and decrease the volume of the pressurized chamber 11.

[0053] The plunger 2 has a large diameter portion 2a and a small diameter portion 2b. When the plunger 2 reciprocates, the large diameter portion 2a and the small diameter portion 2b are located in the auxiliary chamber 17a. Therefore, the volume of the auxiliary chamber 17a increases or decreases with the reciprocating motion of the plunger 2.

[0054] The auxiliary chamber 17a is connected to the fuel passage 10c (see Figure 5 ) communicates with the low-pressure fuel chamber 10. When the plunger 2 descends, fuel flows from the sub-chamber 17a into the low-pressure fuel chamber 10, and when the plunger 2 ascends, fuel flows from the low-pressure fuel chamber 10 into the sub-chamber 17a. This reduces the fuel flow rate in and out of the high-pressure fuel pump 100 during its intake and return strokes, thereby reducing pressure pulsation within the high-pressure fuel pump 100.

[0055] Furthermore, a pressure reducing valve mechanism 4 is provided in the second chamber 1b of the pump body 1, communicating with the pressurizing chamber 11. The pressure reducing valve mechanism 4 includes a seat member 44, a pressure reducing valve 43, a pressure reducing valve retainer 42, and a pressure reducing spring 41. The detailed structure of the pressure reducing valve mechanism 4 will be described later.

[0056] like Figure 3 As shown in FIG, a low pressure fuel chamber 10 is provided on the upper portion of the pump body 1. Figure 4 As shown, a suction joint 5 is mounted on the side of the pump body 1. The suction joint 5 is connected to a low-pressure pipe 104 (see FIG. 1 ) through which the fuel supplied from the fuel tank 103 passes. Figure 1 The fuel in the fuel tank 103 is supplied to the interior of the high-pressure fuel pump 100 from the suction joint 5 .

[0057] The intake joint 5 includes a low-pressure fuel intake port 51 connected to the low-pressure pipe 104, and an intake flow path 52 communicating with the low-pressure fuel intake port 51. A suction filter 53 is provided in the intake flow path 52. Fuel passing through the intake flow path 52 is supplied to the low-pressure fuel chamber 10 through the suction filter 53 provided within the pump body 1. The suction filter 53 removes foreign matter from the fuel, preventing it from entering the high-pressure fuel pump 100.

[0058] The low-pressure fuel chamber 10 is provided with a low-pressure fuel flow path 10a and an intake path 10b (see Figure 2 The low-pressure fuel flow path 10a is provided with a pressure pulsation reducing mechanism 9. The fuel flowing into the pressurizing chamber 11 is again fed to the suction passage 10b (see FIG. 1 ) through the electromagnetic suction valve mechanism 3 in the open valve state. Figure 2 ) returns, pressure pulsation occurs in the low-pressure fuel chamber 10. The pressure pulsation reducing mechanism 9 reduces the pressure pulsation generated in the high-pressure fuel pump 100 and the low-pressure piping 104.

[0059] The pressure pulsation reduction mechanism 9 is formed of a metal film damper, with two corrugated disc-shaped metal plates bonded to its outer circumference. An inert gas such as argon is injected into the damper. The metal film damper of the pressure pulsation reduction mechanism 9 reduces or absorbs pressure pulsations by expanding and contracting.

[0060] The suction passage 10b is connected to the suction port 31b of the electromagnetic suction valve mechanism 3 (see Figure 2 ) is connected, and the fuel that has passed through the low-pressure fuel flow path 10a reaches the suction port 31b of the electromagnetic suction valve mechanism 3 via the suction passage 10b.

[0061] like Figure 2 and Figure 4 As shown, the electromagnetic suction valve mechanism 3 is inserted into the suction valve chamber 30 formed in the pump body 1. The suction valve chamber 30 is located upstream of the pressurized chamber 11 (on the suction passage 10b side) and is formed as a horizontally extending horizontal hole. The electromagnetic suction valve mechanism 3 includes a suction valve seat 31 pressurized into the suction valve chamber 30, a suction valve 32, a rod 33, a rod biasing spring 34, a solenoid coil 35, a movable core 36, a stopper 37, and a suction valve biasing spring 38.

[0062] The suction valve seat 31 is cylindrical and has a seating portion 31a on its inner periphery. Furthermore, a suction port 31b extending from the outer periphery to the inner periphery is formed on the suction valve seat 31. The suction port 31b communicates with the suction passage 10b in the low-pressure fuel chamber 10.

[0063] A stopper 37 is disposed in the suction valve chamber 30, facing the seat 31a of the suction valve seat 31. The suction valve 32 is disposed between the stopper 37 and the seat 31a. Furthermore, an suction valve biasing spring 38 is interposed between the stopper 37 and the suction valve 32. The suction valve biasing spring 38 biases the suction valve 32 toward the seat 31a.

[0064] The suction valve 32 abuts the seat 31a, closing the connection between the suction port 31b and the pressurized chamber 11. This puts the electromagnetic suction valve mechanism 3 in a closed state. Meanwhile, the suction valve 32 abuts the stopper 37, opening the connection between the suction port 31b and the pressurized chamber 11. This puts the electromagnetic suction valve mechanism 3 in an open state.

[0065] The rod 33 extends through the cylindrical hole of the intake valve seat 31. One end of the rod 33 abuts the intake valve 32. A rod biasing spring 34 biases the intake valve 32 toward the stopper 37, i.e., toward the valve opening direction, via the rod 33. One end of the rod biasing spring 34 engages with a flange provided on the outer periphery of the rod 33. The other end of the rod biasing spring 34 engages with a magnetic core 39, which is positioned to surround the rod biasing spring 34.

[0066] The movable core 36 faces the end surface of the magnetic core 39. The movable core 36 engages with a flange portion provided on the outer periphery of the rod 33. The electromagnetic coil 35 is arranged so as to surround the magnetic core 39. The electromagnetic coil 35 is electrically connected to a terminal member 40, and current flows through the terminal member 40.

[0067] In the de-energized state, where no current flows through the electromagnetic coil 35, the rod 33 is biased in the valve-opening direction by the force generated by the rod-biasing spring 34, pressing the intake valve 32 in this direction. As a result, the intake valve 32 moves away from the seat 31a and abuts against the stopper 37, placing the electromagnetic intake valve mechanism 3 in the open state. In other words, the electromagnetic intake valve mechanism 3 is in the normally open state, with the valve open, when de-energized.

[0068] When the electromagnetic intake valve mechanism 3 is open, fuel from the intake port 31b flows between the intake valve 32 and the seat 31a, then through multiple fuel passage holes (not shown) in the stopper 37 and the supply communication hole 1g (described later) before flowing into the pressurized chamber 11. When the electromagnetic intake valve mechanism 3 is open, the intake valve 32 contacts the stopper 37, restricting the position of the intake valve 32 in the open direction. The gap between the intake valve 32 and the seat 31a in the open state represents the movable range of the intake valve 32, which is referred to as the valve opening stroke.

[0069] When a control signal from ECU 101 is applied to electromagnetic suction valve mechanism 3, current flows through electromagnetic coil 35 via terminal member 40. This current flowing through electromagnetic coil 35 pulls movable core 36 in the valve closing direction on the magnetic attraction surface due to the magnetic attraction force of magnetic core 39. As a result, movable core 36 moves against the biasing force of rod biasing spring 34 and comes into contact with magnetic core 39.

[0070] When the movable core 36 is attracted by the magnetic core 39 and moves, the rod 33 moves in the valve closing direction along with the movable core 36. As a result, the force acting in the valve opening direction is released from the intake valve 32, and the valve biasing spring 38 causes the intake valve 32 to move in the valve closing direction. When the intake valve 32 contacts the seating portion 31a of the intake valve seat 31, the electromagnetic intake valve mechanism 3 enters the valve closed state.

[0071] like Figure 4 and Figure 5 As shown, the discharge valve mechanism 8 is disposed in a discharge valve chamber 80 provided on the outlet side (downstream side) of the pressurizing chamber 11. The discharge valve mechanism 8 includes a discharge valve seat member 81 and a discharge valve 82 that contacts and separates from the discharge valve seat member 81. Furthermore, the discharge valve mechanism 8 includes a discharge valve spring 83 that biases the discharge valve 82 toward the discharge valve seat member 81, and a discharge valve stopper 84 that determines the stroke (movement distance) of the discharge valve 82. Furthermore, the discharge valve mechanism 8 includes a plug 85 that blocks fuel leakage to the outside.

[0072] The discharge valve stopper 84 is pressed into the plug 85. The plug 85 is welded to the pump body 1 at the weld portion 86. The discharge valve chamber 80 is opened and closed by the discharge valve 82. The discharge valve chamber 80 is connected to the discharge valve chamber passage 87. The discharge valve chamber passage 87 is formed in the pump body 1.

[0073] The pump body 1 is also provided with a horizontal hole that communicates with the second chamber 1b (pressure reducing valve chamber). A discharge nipple 12 is inserted into this horizontal hole. The discharge nipple 12 includes the aforementioned discharge passage 12a, which communicates with the horizontal hole in the pump body 1 and the discharge valve chamber passage 87, and a fuel outlet 12b at one end of the discharge passage 12a. The fuel outlet 12b of the discharge nipple 12 communicates with the common rail 106. Furthermore, the discharge nipple 12 is welded to the pump body 1 via a weld 12c.

[0074] When there is no fuel pressure difference (so-called fuel differential pressure) between the pressurizing chamber 11 and the discharge valve chamber 80 and discharge valve chamber passage 87, the pressure differential force acting on the discharge valve 82 and the biasing force of the discharge valve spring 83 pressurize the discharge valve 82 against the discharge valve seat member 81. As a result, the discharge valve mechanism 8 is in a closed state. On the other hand, if the fuel pressure in the pressurizing chamber 11 is greater than the fuel pressure in the discharge valve chamber 80 and discharge valve chamber passage 87, and the pressure differential force acting on the discharge valve 82 is greater than the biasing force of the discharge valve spring 83, the discharge valve 82 resists the biasing force of the discharge valve spring 83 and moves away from the discharge valve seat member 81. As a result, the discharge valve mechanism 8 is in an open state.

[0075] When the discharge valve mechanism 8 is in the open state, the high-pressure fuel in the pressurizing chamber 11 passes through the discharge valve mechanism 8 and reaches the discharge valve chamber 80 and the discharge valve chamber passage 87. The fuel reaching the discharge valve chamber passage 87 is discharged to the common rail 106 (see FIG. 1 ) via the fuel outlet 12b of the discharge joint 12. Figure 1 ) is discharged. With the above-described structure, the discharge valve mechanism 8 functions as a check valve that restricts the flow direction of the fuel.

[0076] 1-2. Fuel pump operation

[0077] Next, the operation of the high-pressure fuel pump 100 according to this embodiment will be described.

[0078] exist Figure 1 When the plunger 2 is lowered, the electromagnetic suction valve mechanism 3 opens, and the fuel flows from the supply communication hole 1g into the pressurizing chamber 11. Hereinafter, the stroke of the plunger 2 lowering is referred to as the suction stroke. On the other hand, when the plunger 2 is raised, the electromagnetic suction valve mechanism 3 closes, and the fuel in the pressurizing chamber 11 is pressurized and discharged to the common rail 106 (see FIG. 1 ) through the discharge valve mechanism 8. Figure 1) is pressed and sent. Hereinafter, the stroke in which the plunger 2 rises is referred to as the compression stroke.

[0079] As described above, if the electromagnetic intake valve mechanism 3 is closed during the compression stroke, the fuel drawn into the pressurized chamber 11 during the intake stroke is pressurized and discharged toward the common rail 106. On the other hand, if the electromagnetic intake valve mechanism 3 is opened during the compression stroke, the fuel in the pressurized chamber 11 is forced back toward the supply communication hole 1g and is not discharged toward the common rail 106. Thus, the discharge of fuel by the high-pressure fuel pump 100 is controlled by the opening and closing of the electromagnetic intake valve mechanism 3. The opening and closing of the electromagnetic intake valve mechanism 3 is controlled by the ECU 101.

[0080] During the suction stroke, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 decreases. During the suction stroke, the pressurizing chamber 11 and the suction port 31b (see Figure 2 ) becomes smaller. When the force of the rod biasing spring 34 becomes greater than the fluid pressure differential before and after the suction valve 32, the rod 33 moves in the valve-opening direction, and the suction valve 32 moves away from the seating portion 31a of the suction valve seat 31, and the electromagnetic suction valve mechanism 3 enters the valve-opening state.

[0081] The fuel in the suction port 31 b passes between the suction valve 32 and the seat portion 31 a and flows into the pressurizing chamber 11 through a plurality of holes provided in the stopper 37 .

[0082] After completing the intake stroke, the high-pressure fuel pump 100 transitions to the compression stroke. At this time, the electromagnetic coil 35 remains de-energized, and there is no magnetic attraction between the movable core 36 and the magnetic core 39. The intake valve 32 is subjected to a force in the valve-opening direction corresponding to the difference between the forces of the rod-biasing spring 34 and the valve-biasing spring 38, and a force in the valve-closing direction due to the fluid force generated by the reverse flow of fuel from the pressurization chamber 11 into the low-pressure fuel flow path 10a.

[0083] To maintain the electromagnetic intake valve mechanism 3 in the open state, the difference in force between the rod-biasing spring 34 and the valve-biasing spring 38 is set to be greater than the fluid force. In this state, even if the plunger 2 ascends, the rod 33 remains in the open position, and the intake valve 32, which is biased by the rod 33, similarly remains in the open position. Consequently, the volume of the pressurized chamber 11 decreases as the plunger 2 ascends. In this state, the fuel once drawn into the pressurized chamber 11 returns to the intake passage 10b through the open electromagnetic intake valve mechanism 3, preventing the pressure within the pressurized chamber 11 from rising. This stroke is referred to as the return stroke.

[0084] During the return trip, the ECU 101 (refer to Figure 1) is applied to the electromagnetic suction valve mechanism 3, current flows to the electromagnetic coil 35 via the terminal component 40. When current flows in the electromagnetic coil 35, a magnetic attraction force acts on the magnetic attraction surface of the magnetic core 39 and the movable core 36, and the movable core 36 is attracted to the magnetic core 39. When the magnetic attraction force is greater than the force of the rod-urging spring 34, the movable core 36 moves toward the magnetic core 39 side against the force of the rod-urging spring 34, and the rod 33 engaged with the movable core 36 moves in the direction away from the suction valve 32. As a result, due to the force of the suction valve-urging spring 38 and the fluid force generated by the fuel flowing into the suction passage 10b, the suction valve 32 is seated on the seating portion 31a, and the electromagnetic suction valve mechanism 3 becomes a closed valve state.

[0085] After the electromagnetic suction valve mechanism 3 becomes closed, the fuel in the pressurizing chamber 11 is pressurized as the plunger 2 rises. When the pressure exceeds a predetermined value, the fuel is discharged to the common rail 106 (see FIG. 1 ) through the discharge valve mechanism 8. Figure 1 ) is discharged. This stroke is called the discharge stroke. That is, the compression stroke from the bottom dead center to the top dead center of the plunger 2 consists of the return stroke and the discharge stroke. By controlling the timing of energizing the electromagnetic coil 35 of the electromagnetic intake valve mechanism 3, the amount of high-pressure fuel discharged can be controlled.

[0086] If the timing of energizing the electromagnetic coil 35 is advanced, the proportion of the return stroke in the compression stroke becomes smaller, and the proportion of the discharge stroke becomes larger. As a result, less fuel returns to the intake passage 10b, and more fuel is ejected at high pressure. On the other hand, if the timing of energizing the electromagnetic coil 35 is delayed, the proportion of the return stroke in the compression stroke becomes larger, and the proportion of the discharge stroke becomes smaller. As a result, more fuel returns to the intake passage 10b, and less fuel is ejected at high pressure. In this way, by controlling the timing of energizing the electromagnetic coil 35, the amount of fuel ejected at high pressure can be controlled to the amount required by the engine (internal combustion engine).

[0087] 2. Example of the structure of the pressure reducing valve mechanism, shock wave absorbing part, and supply communication hole

[0088] Next, the detailed structures of the pressure reducing valve mechanism 4 , the shock wave absorbing portion 1 d , and the supply communication hole 1 g will be described.

[0089] 2-1. Pressure reducing valve mechanism

[0090] First, the structure of the pressure reducing valve mechanism 4 is referred to Figure 6 Provide explanation.

[0091] Figure 6 It is a cross-sectional view showing the pressure reducing valve mechanism 4 in an enlarged manner.

[0092] like Figure 6As shown, the pressure reducing valve mechanism 4 includes a pressure reducing spring 41, a pressure reducing valve holder 42, a pressure reducing valve 43, and a seat member 44. The pressure reducing valve mechanism 4 is inserted from the discharge joint 12 and is arranged in the second chamber 1b (pressure reducing valve chamber).

[0093] The pressure-reducing spring 41 is a compression coil spring, one end of which abuts one end of the second chamber 1b in the pump body 1. Furthermore, the other end of the pressure-reducing spring 41 abuts a pressure-reducing valve holder 42. The pressure-reducing valve holder 42 engages with the pressure-reducing valve 43. Therefore, the biasing force of the pressure-reducing spring 41 acts on the pressure-reducing valve 43 via the pressure-reducing valve holder 42.

[0094] The pressure-reducing valve holder 42 includes an abutment portion 42a and an insertion portion 42b connected to the abutment portion 42a. The abutment portion 42a is formed in a disc shape with an appropriate thickness. A locking groove for engaging the pressure-reducing valve 43 is formed on one surface of the abutment portion 42a. Furthermore, a protruding insertion portion 42b is formed on the other surface of the abutment portion 42a and abuts the other end of the pressure-reducing spring 41.

[0095] The insertion portion 42b is formed into a cylindrical shape and is inserted radially inward of the pressure-reducing spring 41. The front end of the insertion portion 42b, which is on the side opposite to the abutment portion 42a, is formed into a circular flat surface and is positioned near the seat surface of the pressure-reducing spring 41, which serves as one end of the pressure-reducing spring 41. The one end of the pressure-reducing spring 41 is the end of the pressure-reducing spring 41 opposite the insertion side (the other end) into which the insertion portion 42b can be inserted. The insertion portion 42b has a tapered portion 42c whose outer diameter decreases as it approaches the front end. The tapered portion 42c begins at a position closer to the pressure-reducing valve 43 than the portion of the pressure-reducing spring 41 where a gap is formed between adjacent rings.

[0096] The pressure-reducing spring 41, in its compressed state, is interposed between one end of the second chamber 1b, namely the shock wave absorbing portion 1d (described later), and the abutment portion 42a of the pressure-reducing valve holder 42. The compression of the pressure-reducing spring 41 biases the pressure-reducing valve holder 42 and the pressure-reducing valve 43 toward the seat member 44. Therefore, it is believed that adjacent rings contact each other at the ends of the pressure-reducing spring 41. Even if the tapered portion 42c is provided at this contacting portion of the adjacent rings, the fuel between the pressure-reducing spring 41 and the tapered portion 42c is prevented from moving radially outward of the pressure-reducing spring 41.

[0097] On the other hand, as shown in this embodiment, a tapered portion 42c is disposed in the portion of the pressure relief spring 41 where a gap is formed between adjacent rings. This facilitates the flow of fuel between the pressure relief spring 41 and the tapered portion 42c from between adjacent rings of the pressure relief spring 41 to the radially outer side of the pressure relief spring 41. As a result, fuel can be efficiently drawn into the pressurized chamber 11.

[0098] The pressure-reducing valve 43 is pressed by the force of the pressure-reducing spring 41, thereby blocking the fuel passage 44a of the seat member 44. The direction of movement of the pressure-reducing valve 43 and the pressure-reducing valve holder 42 is perpendicular to the direction of reciprocation of the plunger 2 and is the same as the direction of movement of the intake valve 32 in the electromagnetic intake valve mechanism 3. The centerline of the pressure-reducing valve mechanism 4 (the centerline of the pressure-reducing valve holder 42) is perpendicular to the centerline of the plunger 2.

[0099] Seat member 44 has a fuel passage 44a facing pressure reducing valve 43. The side of fuel passage 44a opposite pressure reducing valve 43 communicates with discharge passage 12a. The movement of fuel between pressurized chamber 11 (upstream side) and seat member 44 (downstream side) is blocked by contact (close contact) between pressure reducing valve 43 and seat member 44, thereby blocking fuel passage 44a.

[0100] When the pressure in the discharge valve chamber 80, the discharge valve chamber passage 87, the common rail 106, and the components immediately preceding it increases, the pressure difference with the pressure in the second chamber 1b (the pressure-reducing valve chamber) exceeds the set value. As a result, the fuel on the seat member 44 side presses against the pressure-reducing valve 43, causing it to move against the force of the pressure-reducing spring 41. Consequently, the pressure-reducing valve 43 opens, and the fuel in the discharge passage 12a returns to the pressurizing chamber 11 through the fuel passage 44a of the seat member 44. The pressure that opens the pressure-reducing valve 43 is determined by the force of the pressure-reducing spring 41.

[0101] The direction of movement of the pressure-reducing valve 43 and the pressure-reducing valve retainer 42 in the pressure-reducing valve mechanism 4 is different from the direction of movement of the discharge valve 82 in the discharge valve mechanism 8. Specifically, the discharge valve 82 in the discharge valve mechanism 8 moves in a first radial direction of the pump body 1, while the pressure-reducing valve 43 in the pressure-reducing valve mechanism 4 moves in a second radial direction that is different from the first radial direction of the pump body 1. This allows the discharge valve mechanism 8 and the pressure-reducing valve mechanism 4 to be positioned so that they do not overlap in the vertical direction, making full use of the space inside the pump body 1 and achieving a reduction in the size of the pump body 1.

[0102] 2-2. Shock Wave Absorber and Supply Through Hole

[0103] Next, refer to Figure 6 、 Figure 7A and Figure 7B The detailed structures of the shock wave absorbing portion 1d and the supply communication hole 1g will be described.

[0104] Figure 7A 1 is a front view showing the shock wave absorbing portion 1d and the supply communication hole 1g. Figure 7B It is a perspective view showing the shock wave absorbing portion 1d and the supply communication hole 1g.

[0105] like Figure 6 and Figure 7AAs shown, a shock wave absorber 1d is provided in the second chamber 1b, which serves as the pressure reducing valve chamber. This shock wave absorber 1d is positioned between the suction valve chamber 30 and the second chamber 1b in the pump body 1. In this example, the shock wave absorber 1d forms a wall that forms the second chamber 1b, that is, a wall that separates the suction valve chamber 30 from the second chamber 1b. This shock wave absorber 1d prevents fuel from directly reciprocating between the second chamber 1b, which serves as the pressure reducing valve chamber, and the suction valve chamber 30.

[0106] In addition, if Figure 6 As shown, the shock wave absorbing portion 1d faces the front end of the insertion portion 42b of the pressure reducing valve retainer 42. The shock wave absorbing portion 1d abuts the other end of the pressure reducing spring 41, opposite to the end abutting the abutting portion 42a of the pressure reducing valve retainer 42. In other words, the shock wave absorbing portion 1d is positioned downstream in the direction of movement of the pressure reducing valve retainer 42 when the pressure reducing valve mechanism 4 is released.

[0107] Here, when the pressure in the discharge valve chamber 80, the discharge valve chamber passage 87, the common rail 106, and the components preceding it increases, and when the pressure difference with the pressure in the second chamber 1b (the pressure reducing valve chamber) exceeds a set value, the pressure reducing valve 43 opens. The fuel in the discharge passage 12a flows through the fuel passage 44a of the seat member 44.

[0108] Furthermore, when the pressure-reducing valve 43 opens, a shock wave is generated that propagates axially along the insertion portion 42b of the pressure-reducing valve holder 42. As described above, the shock wave absorber 1d is provided at the axial end of the insertion portion 42b. Therefore, the shock wave generated when the pressure-reducing valve 43 opens propagates axially along the insertion portion 42b of the pressure-reducing valve holder 42 and collides with the shock wave absorber 1d.

[0109] Thus, the shock wave absorbing portion 1d can absorb the shock wave generated when the pressure reducing valve 43 is opened. As a result, it is possible to suppress damage to various mechanism components such as the pressure pulsation reducing mechanism 9 and the low-pressure piping 104 disposed upstream of the pressure reducing valve mechanism 4 caused by the shock wave generated when the pressure reducing valve mechanism 4 is released.

[0110] In addition, while this example illustrates the shock wave absorber 1d as a wall provided on the pump body 1, the present invention is not limited to this configuration. The shock wave absorber 1d can also be formed as a flange provided on the insertion portion 42b of the pressure reducing valve retainer 42, or as a convex portion projecting from the inner wall surface of the second chamber 1b, which serves as the pressure reducing valve chamber. In other words, the shock wave absorber 1d only needs to be provided in a position relative to the direction of movement of the pressure reducing valve retainer 42. Furthermore, by forming the shock wave absorber 1d as a wall separating the second chamber 1b, which serves as the pressure reducing valve chamber, from the suction valve chamber 30, the number of components can be reduced.

[0111] Furthermore, the shock wave absorbing portion 1d is not limited to a planar member, and may be, for example, a tapered recessed portion whose diameter decreases along the direction in which the shock wave travels.

[0112] In addition, if Figure 6 、 Figure 7A and Figure 7B As shown, the first chamber 1a, which constitutes the pressurizing chamber 11, communicates with the suction valve chamber 30 via two supply communicating holes 1g. The two supply communicating holes 1g extend perpendicularly to the centerline of the first chamber 1a. Furthermore, the two supply communicating holes 1g are formed closer to the plunger 2 than the communicating hole 1e, which connects the first chamber 1a with the second chamber 1b. The two supply communicating holes 1g are connected to the side surface of the first chamber 1a.

[0113] In addition, if Figure 6 As shown, the open ends of the two supply communication holes 1g are located at the upper starting point of the plunger 2, where the volume of the pressurized chamber 11 is minimized, closer to the second chamber 1b than the end of the plunger 2, that is, upstream in the direction of movement of the plunger 2. Specifically, the two supply communication holes 1g are formed at a position not blocked by the side circumferential surface of the plunger 2, at the upper starting point of the plunger 2, where the volume of the pressurized chamber 11 is minimized.

[0114] Furthermore, as the plunger 2 approaches its bottom dead center, where the volume of the pressurizing chamber 11 is maximized, the area of ​​the supply communication hole 1g communicating with the pressurizing chamber increases. This allows the pressurizing chamber 11 to communicate with the intake valve chamber 30 via the supply communication hole 1g, regardless of the position of the plunger 2. As a result, a sufficient flow rate of fuel can be ensured, both from the intake valve chamber 30 to the pressurizing chamber 11 and vice versa.

[0115] Furthermore, when the plunger 2 descends, drawing fuel from the intake valve chamber 30 into the pressurizing chamber 11, the pressure loss increases, and if the fuel pressure falls below the saturated vapor pressure, some of the fuel vaporizes, preventing the pressurizing chamber 11 from being completely filled with liquid, leading to a decrease in volumetric efficiency. Volumetric efficiency refers to the ratio of the amount of fuel discharged from the discharge valve mechanism 8 to the distance traveled from the bottom dead center of the plunger 2, where the volume of the pressurizing chamber 11 is maximized, to the top dead center of the plunger 2, where the volume of the pressurizing chamber 11 is minimized.

[0116] In contrast, as described above, since the flow rate of fuel from the intake valve chamber 30 to the pressurizing chamber 11 or from the pressurizing chamber 11 to the intake valve chamber 30 through the supply communication hole 1g can be sufficiently ensured, pressure loss can be reduced.

[0117] Furthermore, the opening area of ​​the two supply communication holes 1g connecting the pressurization chamber 11 with the intake valve chamber 30 is set to be smaller than the opening area of ​​the communication hole 1e connecting the pressurization chamber 11 with the second chamber 1b, which serves as the pressure-reducing valve chamber. This allows the shock wave generated when the pressure-reducing valve mechanism 4 is released to be attenuated not only by the shock wave absorber 1d but also by the supply communication holes 1g. By utilizing the pressurization chamber 11 as the shock wave attenuation space, the need for a separate attenuation space is eliminated, leading to a more compact device overall.

[0118] Furthermore, the axial directions of the opening axes of the two supply communication holes 1g intersect with the axial directions of the opening axes of the first chamber 1a and the communication hole 1e. This further reduces the transmission of the shock wave generated in the second chamber 1b to the suction valve chamber 30.

[0119] In addition, the supply communication hole 1g is not limited to the above example, as described later Figure 8A and Figure 8B As shown, various other shapes can be applied.

[0120] Figure 8A and Figure 8B It is a diagram showing a modified example of the supply communication hole.

[0121] Figure 8A and Figure 8B The supply communication hole 1gB shown is formed into a substantially elliptical shape obtained by combining two circular communication holes. The supply communication hole 1gB connects the first chamber 1a constituting the pressurizing chamber 11 with the suction valve chamber 30. Figure 7A and Figure 7B The supply communication holes 1g shown are the same, and therefore description thereof will be omitted. Figure 8A and Figure 8B The supply connecting hole 1gB shown can also obtain Figure 7A and Figure 7B The supply communication hole 1g shown in FIG.

[0122] The above describes the embodiments of the fuel pump of the present invention, including their functions and effects. However, the fuel pump of the present invention is not limited to the above embodiments and can be implemented in various variations without departing from the scope of the invention. Furthermore, the above embodiments are described in detail to facilitate understanding of the present invention and are not necessarily limited to having all the described structures.

[0123] Furthermore, in the above-described embodiment, the second chamber 1b, serving as the pressure-reducing valve chamber, is adjacent to the suction valve chamber 30, and the centerline of the second chamber 1b and the centerline of the suction valve chamber 30 are arranged in the same plane. However, this is not limiting. The second chamber 1b, serving as the pressure-reducing valve chamber, and the suction valve chamber 30 may also exist in different planes. For example, the centerline of the second chamber 1b and the centerline of the suction valve chamber 30 may not be parallel but may be at an angle. Furthermore, the centerline of the second chamber 1b and the centerline of the suction valve chamber 30 may be parallel, but may be offset, or the centerline of the second chamber 1b and the centerline of the suction valve chamber 30 may be offset and not parallel but at an angle.

[0124] In addition, in this specification, terms such as "parallel" and "orthogonal" are used, but they do not only mean strictly "parallel" and "orthogonal", but can also mean "approximately parallel" and "approximately orthogonal" within the range that includes "parallel" and "orthogonal" and can perform their functions.

[0125] Description of Reference Signs

[0126] 1...Pump body, 1a...First chamber, 1b...Second chamber (pressure reducing valve chamber), 1c...Third chamber, 1d...Shock wave absorber, 1e...Communication hole, 1f...Conical surface, 1g, 1gB...Supply communication hole, 2...Plunger, 3...Solenoid suction valve mechanism, 4...Pressure reducing valve mechanism, 5...Suction joint, 6...Cylinder, 8...Discharge valve mechanism, 9...Pressure pulsation reducing mechanism (damping), 10...Low-pressure fuel chamber, 10a...Low-pressure fuel flow path, 10b...Suction passage, 10c...Fuel passage, 11...Compressing chamber, 12...Discharge joint, 30...Suction valve chamber, 31...Suction valve seat, 31a... Seating portion, 31b…suction port, 32…suction valve, 41…pressure reducing spring, 42…pressure reducing valve retainer, 42a…abutting portion, 42b…insertion portion, 42c…tapered portion, 43…pressure reducing valve, 44…seat component, 44a…fuel passage, 51…low-pressure fuel suction port, 52…suction flow path, 53…suction filter, 80…discharge valve chamber, 87…discharge valve chamber passage, 100…high-pressure fuel pump, 101…ECU, 102…feed pump, 103…fuel tank, 104…low-pressure piping, 105…fuel pressure sensor, 106…common rail, 107…injector

Claims

1. A fuel pump, characterized in that: include: damper; a suction valve chamber communicating with the damper via a suction passage; a pressurizing chamber formed on a downstream side of the suction valve chamber; a pressure reducing valve chamber formed on a downstream side of the pressurizing chamber; a pressure reducing valve mechanism disposed in the pressure reducing valve chamber and having a pressure reducing valve retainer; and a shock wave absorbing portion provided in the pressure reducing valve chamber and arranged to face the pressure reducing valve holder on the downstream side in the moving direction of the pressure reducing valve holder when the pressure reducing valve mechanism is released; The shock wave absorbing portion is a wall that separates the pressure reducing valve chamber from the suction valve chamber. The pressure reducing valve chamber and the suction valve chamber are communicated via the pressurizing chamber. An opening area of ​​a supply communication hole communicating between the pressurizing chamber and the suction valve chamber is set smaller than an opening area of ​​a communication hole communicating between the pressure reducing valve chamber and the pressurizing chamber.

2. The fuel pump according to claim 1, wherein: The pressure reducing valve mechanism comprises: a pressure reducing valve engaged with the pressure reducing valve holder; and A decompression spring has one end portion abutting against the decompression valve holder and the other end portion abutting against the shock wave absorbing portion.

3. The fuel pump according to claim 1, wherein: A plunger is inserted into the pressurized chamber to increase or decrease the volume of the pressurized chamber. The supply communication hole is formed at a position not blocked by the side peripheral surface of the plunger at the top dead center of the plunger where the volume of the pressurizing chamber is most reduced.

4. The fuel pump according to claim 1, wherein: The axial direction of the opening axis of the supply communication hole intersects with the axial directions of the opening axes of the pressurizing chamber and the communication hole.

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