Fuel pump

Abstract

This invention provides a fuel pump capable of suppressing plunger fixation. The fuel pump of this invention includes: a plunger 2 that reciprocates; a cylinder 6, wherein a guide hole 6a guiding the reciprocating motion of the plunger 2 extends axially; and a pump body 1 that holds the cylinder 6. The pump body 1 has: a cylinder insertion hole 1g into which the cylinder 6 is inserted; and a pressurization chamber 11 communicating with the cylinder insertion hole 1g, the volume of which increases or decreases due to the reciprocating motion of the plunger 2. The cylinder 6 has: a pressing portion 6b pressed into the inner circumferential surface of the cylinder insertion hole 1g; and a groove 6d formed on the inner circumferential surface of the guide hole 6a at a position corresponding to the pressing portion 6b.

Description

Technical Field

[0001] This invention relates to a fuel pump for an internal combustion engine in an automobile. Background Technology

[0002] In true injection engines that directly inject fuel into the combustion chamber of an engine (internal combustion engine) such as a car, a high-pressure fuel pump is widely used to maintain high fuel pressure. Prior art for such a high-pressure fuel pump is described, for example, in Patent Document 1.

[0003] Patent Document 1 describes a high-pressure fuel pump comprising: a pump body forming a pressurization chamber, and a cylinder inserted into a bore formed in the pump body. The cylinder is configured such that a radially outwardly protruding portion on the side opposite to the pressurization chamber is pressed into the bore, engaging with the bore via a thread. Alternatively, the cylinder is configured to be fastened to the bore by securing the opposite side of the pressurization chamber. A radial clearance is formed between the cylinder and the bore of the pump body over the entire area from the engagement portion to the upper end.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1 International Publication No. 2018 / 186219 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] However, in the high-pressure fuel pump described in Patent Document 1, by pressurizing the fuel, the temperature of the fuel in the pressurization chamber rises, and this heat is transferred to the vicinity of the cylinder's inlet portion in the pump body. Furthermore, the vicinity of the cylinder's inlet portion in the pump body deforms due to the heat, thereby deforming the cylinder inward. As a result, the plunger is compressed and fixed.

[0009] The purpose of this invention is to address the aforementioned problems by providing a fuel pump capable of suppressing plunger fixation.

[0010] Technical solutions for solving technical problems

[0011] To solve the above-mentioned technical problems and achieve the objectives of the present invention, the fuel pump of the present invention includes: a plunger that reciprocates; a cylinder, wherein a guide hole for guiding the reciprocating motion of the plunger extends axially; and a pump body for holding the cylinder. The pump body has: a cylinder insertion hole into which the cylinder is inserted; and a pressurization chamber communicating with the cylinder insertion hole, the volume of which increases or decreases due to the reciprocating motion of the plunger. The cylinder has: a press-in portion pressed into the inner circumferential surface of the cylinder insertion hole; and a groove formed on the inner circumferential surface of the guide hole at a position corresponding to the press-in portion.

[0012] The effects of the invention

[0013] The fuel pump with the above structure can suppress plunger fixation.

[0014] Furthermore, the technical issues, structures, and effects other than those mentioned above will become clearer from the following description of the implementation methods. Attached Figure Description

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

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

[0017] Figure 3 This is a horizontal cross-sectional view taken from above the high-pressure fuel pump according to one embodiment of the present invention.

[0018] Figure 4 This is a longitudinal cross-sectional view (2) of a high-pressure fuel pump according to one embodiment of the present invention.

[0019] Figure 5 This is an exploded perspective view of a high-pressure fuel pump according to one embodiment of the present invention.

[0020] Figure 6 This is a longitudinal cross-sectional view of the cylinder area of ​​a high-pressure fuel pump according to one embodiment of the present invention.

[0021] Figure 7 This is an enlarged longitudinal cross-sectional view of the cylinder of a high-pressure fuel pump according to one embodiment of the present invention.

[0022] Figure 8 This is a cross-sectional view of the cylinder of a high-pressure fuel pump according to one embodiment of the present invention, viewed from an obliquely upward angle. Detailed Implementation

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

[0024] The high-pressure fuel pump according to one embodiment of the present invention will now be described. Furthermore, common components are labeled with the same reference numerals in all the figures.

[0025] (Fuel supply system)

[0026] First, use Figure 1 The fuel supply system using the high-pressure fuel pump of this embodiment will be described.

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

[0028] like Figure 1As shown, the fuel supply system 200 includes: a high-pressure fuel pump 100, an ECU (Engine Control Unit) 101, a fuel tank 103, a common rail 106, and multiple injectors 107. The components of the high-pressure fuel pump 100 are integrally assembled in the pump body 1.

[0029] Fuel in fuel tank 103 is drawn by feed pump 102 driven by a signal from ECU 101. The drawn fuel is pressurized to the appropriate pressure by a pressure regulator (not shown) and delivered through low-pressure piping 104 to low-pressure fuel inlet 51 of high-pressure fuel pump 100.

[0030] A high-pressure fuel pump 100 pressurizes the fuel supplied from the fuel tank 103 and delivers it to the common rail 106. Multiple injectors 107 and a fuel pressure sensor 105 are installed on the common rail 106. The multiple injectors 107 are installed in proportion to the number of cylinders (combustion chambers) and inject fuel according to the drive current output from the ECU 101. The fuel supply system 200 of this embodiment is a so-called direct injection engine system in which the injectors 107 directly inject fuel into the cylinders of the engine.

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

[0032] The ECU 101 controls the driving of the high-pressure fuel pump 100 and the multiple injectors 107 based on calculations of fuel pressure (target fuel pressure), etc. That is, the ECU 101 has 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 metal damper (also called a shock absorber) 9 as a pressure pulsation reduction mechanism, an electromagnetic intake valve mechanism 3 as a capacity variable mechanism, an overflow valve (safety valve) mechanism 4, and a discharge valve mechanism 8. Fuel flowing in from the low-pressure fuel intake port 51 passes through the metal damper 9 and the intake passage 10b to reach the intake port 31b of the electromagnetic intake valve mechanism 3.

[0034] Fuel flowing into the electromagnetic intake valve mechanism 3 passes through the intake valve 32, and after passing through the intake passage 1a formed in the pump body 1, flows into the pressurization chamber 11. The pump body 1 slidably holds the plunger 2. The plunger 2 is held in place by the engine cam 91 (see reference). Figure 2It transmits power and reciprocates. One end of the plunger 2 is inserted into the pressurization chamber 11, causing the volume of the pressurization chamber 11 to increase or decrease.

[0035] In the pressurization chamber 11, fuel is drawn in from the solenoid intake valve mechanism 3 during the downward stroke of the plunger 2, and pressurized during the upward stroke of the plunger 2. When the fuel pressure in the pressurization chamber 11 exceeds a set value, the discharge valve mechanism 8 opens, pumping high-pressure fuel to the common rail 106 via the discharge passage 1f. The discharge of fuel from the high-pressure fuel pump 100 is operated by the opening and closing of the solenoid intake valve mechanism 3. The opening and closing of the solenoid intake valve mechanism 3 is controlled by the ECU 101.

[0036] In the event of abnormally high pressure in the common rail 106 due to a malfunction of injector 107, etc., when the fuel outlet 12a (refer to) connected to the common rail 106... Figure 2 When the differential pressure between the pressure chamber 11 and the pressure chamber 11 exceeds the opening pressure (specified value) of the relief valve mechanism 4, the relief valve mechanism 4 opens. As a result, the abnormally high-pressure fuel is returned to the pressure chamber 11 through the relief valve mechanism 4. Consequently, piping such as the common rail 106 is protected.

[0037] (High-pressure fuel pump)

[0038] Next, use Figures 2-4 The structure of the high-pressure fuel pump 100 is described.

[0039] Figure 2 The image shows a longitudinal section view (1) of the high-pressure fuel pump 100, which is orthogonal to the horizontal direction. Figure 3 This is a horizontal cross-sectional view of the high-pressure fuel pump 100, observed at a section orthogonal to the vertical direction. Figure 4 The image shown is a longitudinal section view (Figure 2) of the high-pressure fuel pump 100, which is orthogonal to the horizontal direction.

[0040] like Figure 2 and Figure 3 As shown, the pump body 1 of the high-pressure fuel pump 100 is provided with the aforementioned suction channel 1a and mounting flange 1b (see reference). Figure 3 The mounting flange 1b is tightly fitted against the fuel pump mounting portion 90 of the engine (internal combustion engine) and secured with a plurality of bolts (screws) not shown. That is, the high-pressure fuel pump 100 is secured to the fuel pump mounting portion 90 by the mounting flange 1b.

[0041] like Figure 2 As shown, an O-ring 93, representing a specific example of a valve seat component, is provided between the fuel pump mounting portion 90 and the pump body 1. This O-ring 93 prevents engine oil from leaking to the outside of the engine (internal combustion engine) through the space between the fuel pump mounting portion 90 and the pump body 1.

[0042] Additionally, a cylinder 6, which guides the reciprocating motion of the plunger 2, is installed in the pump body 1 of the high-pressure fuel pump 100. The cylinder 6 is cylindrical and is pressed into the pump body 1 on its outer periphery. The pump body 1 and cylinder 6 are connected to the electromagnetic intake valve mechanism 3, the plunger 2, and the discharge valve mechanism 8 (see reference). Figure 4 Together they form a pressurized chamber 11.

[0043] A fixing part 1c is provided in the pump body 1, which engages with the central part of the cylinder 6 in the axial direction. The fixing part 1c is formed to be plastically deformable. The fixing part 1c pulls the cylinder 6 upward ( Figure 2 The upper end face (one end face) of cylinder 6 is pushed against the pump body 1. As a result, the fuel pressurized in the pressurization chamber 11 will not leak from between the upper end face of engine 6 and pump body 1.

[0044] A tappet (also called a pushrod) 92 is provided at the lower end of the plunger 2. The tappet 92 converts the rotational motion of the cam 91 mounted on the engine camshaft into up-and-down motion and transmits it to the plunger 2. The plunger 2 is pressed against the tappet 92 by the spring 16 via the retainer 15, which applies force to the cam 91 side. The plunger 2 and the tappet 92 reciprocate together, causing the volume of the pressurized chamber 11 to change.

[0045] Additionally, a sealing retainer 17 is disposed between the cylinder 6 and the retainer 15. The sealing retainer 17 is formed as a cylindrical shape into which the plunger 2 can be inserted. A secondary chamber 17a is formed at the upper end of the sealing retainer 17 located on the cylinder 6 side. On the other hand, a plunger seal 18 is retained at the lower end of the sealing retainer 17 located on the retainer 15 side.

[0046] The plunger seal 18 is slidably in contact with the outer periphery of the plunger 2. When the plunger 2 reciprocates, the plunger seal 18 seals the fuel in the auxiliary chamber 17a, preventing the fuel in the auxiliary chamber 17a from flowing into the engine. In addition, the plunger seal 18 prevents lubricating oil (including engine oil) that lubricates the sliding parts in the engine from flowing into the pump body 1.

[0047] exist Figure 2 In this configuration, the plunger 2 reciprocates in the vertical direction. When the plunger 2 descends, the volume of the pressurized chamber 11 expands; when the plunger 2 rises, the volume of the pressurized chamber 11 decreases. That is, the plunger 2 is configured to reciprocate in the direction that expands and contracts the volume of the pressurized chamber 11.

[0048] 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 due to the reciprocating motion of the plunger 2.

[0049] Auxiliary chamber 17a is connected to fuel passage 10c (see reference). Figure 3It is connected to the low-pressure fuel chamber 10. When the plunger 2 descends, a fuel flow is generated from the auxiliary chamber 17a to the low-pressure fuel chamber 10, and when the plunger 2 rises, a fuel flow is generated from the low-pressure fuel chamber 10 to the auxiliary chamber 17a. As a result, the fuel flow to and from the pump during the suction or return stroke of the high-pressure fuel pump 100 can be reduced, and the pressure pulsation generated inside the high-pressure fuel pump 100 can be reduced.

[0050] Additionally, the pump body 1 is provided with an overflow valve mechanism 4 that communicates with the pressurization chamber 11. The overflow valve (also known as a safety valve) mechanism 4 has a safety spring 41, an overflow valve retainer 42, an overflow valve 43, a valve seat component 44, and a spring support component 45.

[0051] The valve seat assembly 44 includes the safety spring 41 to form an overflow valve chamber. One end of the safety spring 41 abuts against the spring support assembly 45, and the other end abuts against the overflow valve retainer 42. The overflow valve retainer 42 engages with the overflow valve 43. The force exerted by the safety spring 41 is applied to the overflow valve 43 via the overflow valve retainer 42.

[0052] The relief valve 43 is pushed by the force of the safety spring 41, blocking the fuel passage of the valve seat component 44. The fuel passage of the valve seat component 44 is connected to the discharge passage 1f (see reference). Figure 3 The flow of fuel between the pressurization chamber 11 (upstream side) and the valve seat component 44 (downstream side) is cut off by contacting (pressuring) the overflow valve 43 with the valve seat component 44.

[0053] When the pressure in the component upstream of the common rail 106 increases, the fuel on the valve seat component 44 pushes against the relief valve 43, resisting the force of the safety spring 41, causing the relief valve 43 to move. As a result, the relief valve 43 opens, and the fuel in the discharge channel 1f returns to the pressurization chamber 11 through the fuel passage of the valve seat component 44. Therefore, the pressure that causes the relief valve 43 to open is determined by the force of the safety spring 41.

[0054] In addition, the overflow valve mechanism 4 of this embodiment is connected to the pressurization chamber 11, but is not limited to this. For example, it can also be connected to the low-pressure channel (low-pressure fuel inlet 51, inlet channel 10b, etc.).

[0055] like Figure 3 and Figure 4 As shown, a suction connector 5 is installed on the side of the pump body 1. The suction connector 5 connects to a low-pressure pipe 104 (see reference 104) through which fuel supplied from the fuel tank 103 passes. Figure 1 Fuel from fuel tank 103 is supplied from suction connector 5 to the interior of high-pressure fuel pump 100.

[0056] The intake connector 5 has: a low-pressure fuel intake port 51 connected to the low-pressure piping 104 and an intake flow path 52 communicating with the low-pressure fuel intake port 51. Fuel passing through the intake flow path 52 is then passed through a metal damper 9 located in the low-pressure fuel chamber 10 and an intake passage 10b (see reference 10b). Figure 2 The suction port 31b of the electromagnetic suction valve mechanism 3 (refer to...) Figure 2 ).like Figure 4 As shown, an intake filter 53 is installed in the fuel passage that communicates with the intake flow path 52. The intake filter 53 removes foreign objects present in the fuel and prevents foreign objects from entering the high-pressure fuel pump 100.

[0057] like Figure 2 and Figure 4 As shown, a low-pressure fuel chamber (damper chamber) 10 is provided in the pump body 1 of the high-pressure fuel pump 100. This low-pressure fuel chamber 10 is covered by a damper cover 14. The damper cover 14 is, for example, formed as a cylindrical (cup-shaped) tube closed on one side.

[0058] like Figure 2 As shown, the low-pressure fuel chamber 10 has a low-pressure fuel flow path 10a and a suction channel 10b. The suction channel 10b is connected to the suction port 31b of the electromagnetic suction valve mechanism 3. Fuel passing through the low-pressure fuel flow path 10a reaches the suction port 31b of the electromagnetic suction valve mechanism 3 via the suction channel 10b.

[0059] A metal damper 9, a first retaining member 19, and a second retaining member 20 are provided in the low-pressure fuel flow path 10a. When fuel flows into the pressurization chamber 11, it returns to the intake passage 10b (refer to...) through the electromagnetic intake valve mechanism 3 in the open state. Figure 2 When the pressure pulsation occurs in the low-pressure fuel chamber 10, pressure pulsation is generated. The metal damper 9 reduces the impact of the pressure pulsation generated in the high-pressure fuel pump 100 on the low-pressure piping 104.

[0060] like Figure 3 As shown, the electromagnetic suction valve mechanism 3 is inserted into the transverse hole formed in the pump body 1. The electromagnetic suction valve mechanism 3 includes: a suction valve seat 31 pressed into the transverse hole formed in the pump body 1, a suction valve 32, a rod 33, a rod force spring 34, an electromagnetic coil (solenoid) 35, and an anchor 36.

[0061] The suction valve seat 31 is cylindrical, and a seating portion 31a is provided on its inner periphery. Additionally, a suction port 31b is formed on the suction valve seat 31, extending from the outer periphery to the inner periphery (see reference). Figure 2 The intake port 31b is connected to the intake passage 10b of the low-pressure fuel chamber 10.

[0062] A stop member 37 is disposed in a transverse hole formed in the pump body 1, opposite to the seat portion 31a of the suction valve seat 31. The suction valve 32 is disposed between the stop member 37 and the seat portion 31a. In addition, a valve force spring 38 is provided between the stop member 37 and the suction valve 32. The valve force spring 38 applies force to the suction valve 32 toward the seat portion 31a.

[0063] The suction valve 32 closes the connection between the suction port 31b and the pressurization chamber 11 by abutting against the seating portion 31a. This puts the electromagnetic suction valve mechanism 3 in a closed state. Conversely, the suction valve 32 opens the connection between the suction port 31b and the pressurization chamber 11 by abutting against the stop member 37. This puts the electromagnetic suction valve mechanism 3 in an open state.

[0064] Rod 33 passes through suction valve seat 31. One end of rod 33 abuts against suction valve 32. Rod force spring 34 applies force to suction valve 32 via rod 33 in the valve opening direction towards stop 37. One end of rod force spring 34 engages with the other end of rod 33. The other end of rod force spring 34 engages with magnetic core 39 arranged to surround rod force spring 34.

[0065] The end face of the anchor 36 faces the end face of the magnetic core 39. The anchor 36 engages with the flange provided on the outer periphery of the rod 33. In addition, one end of the anchor force spring 40 engages with the part of the anchor 36 located on the opposite side of the magnetic core 39. The other end of the anchor force spring 40 abuts against the suction valve seat 31. The anchor force spring 40 applies force to the anchor 36 on the flange side of the rod 33. The amount of movement of the anchor 36 is set to be greater than the amount of movement of the suction valve 32. As a result, the suction valve 32 can reliably abut against (settle) the seat portion 31a, and the electromagnetic suction valve mechanism 3 can be reliably kept in the closed state.

[0066] The electromagnetic coil 35 is arranged so as to wrap around the magnetic core 39 once. Terminal component 30 (see reference) Figure 2 The electromagnetic coil 35 is electrically connected to the terminal component 30, and current flows through the electromagnetic coil 35. In the de-energized state (no current flows through the electromagnetic coil 35), the rod 33 is forced in the opening direction by the force of the rod force spring 34, pressing the suction valve 32 in the opening direction. As a result, the suction valve 32 moves away from the seat 31a and abuts against the stop member 37, and the electromagnetic suction valve mechanism 3 is in the open state. That is, the electromagnetic suction valve mechanism 3 is a normally open type, opening when not energized.

[0067] In the open state of the electromagnetic intake valve mechanism 3, fuel from the intake port 31b flows into the pressurization chamber 11 through the intake valve 32 and the seat portion 31a, and through multiple fuel passage holes (not shown) of the stop member 37 and the intake passage 1a. In the open state of the electromagnetic intake valve mechanism 3, the position of the opening direction of the intake valve 32 is restricted because the intake valve 32 is in contact with the stop member 37. Furthermore, in the open state of the electromagnetic intake valve mechanism 3, the gap between the intake valve 32 and the seat portion 31a is the movable range of the intake valve 32, which is called the opening stroke.

[0068] When current flows through the electromagnetic coil 35, the magnetic attraction acts on the respective magnetic attraction surfaces of the anchor 36 and the magnetic core 39. That is, the anchor 36 is attracted by the magnetic core 39. As a result, the anchor 36 moves against the force of the rod-applying spring 34 and comes into contact with the magnetic core 39. When the anchor 36 moves toward the magnetic core 39 (in the valve-closing direction), the rod 33, which engages with the anchor 36, moves together with the anchor 36. As a result, the suction valve 32 is released from the force in the valve-opening direction and moves toward the valve-closing direction due to the force of the valve-applying spring 38. When the suction valve 32 contacts the seat portion 31a of the suction valve seat 31, the electromagnetic suction valve mechanism 3 becomes closed.

[0069] like Figure 3 As shown, the discharge valve mechanism 8 is connected to the outlet side of the pressurized chamber 11. The discharge valve mechanism 8 includes a discharge valve seat component 81 and a discharge valve 82 that contacts and separates from the discharge valve seat component 81. Furthermore, the discharge valve mechanism 8 includes a discharge valve spring 83 that applies force to the discharge valve 82 towards the discharge valve seat component 81; a discharge valve stop 84 that determines the stroke (travel distance) of the discharge valve 82; and a plug 85 that stops the movement of the discharge valve stop 84.

[0070] The discharge valve seat assembly 81, discharge valve 82, discharge valve spring 83, and discharge valve stop 84 are housed in the discharge valve chamber 1d formed in the pump body 1. The discharge valve chamber 1d is a generally cylindrical space extending horizontally. One end of the discharge valve chamber 1d communicates with the pressurization chamber 11 via the fuel passage 1e. The other end of the discharge valve chamber 1d opens to the side of the pump body 1. The opening at the other end of the discharge valve chamber 1d is sealed by a pin 85.

[0071] Additionally, the discharge connector 12 is joined to the pump body 1 via a welded portion 12b. The discharge connector 12 has a fuel discharge port 12a. The fuel discharge port 12a communicates with the discharge valve chamber 1d via a discharge passage 1f extending horizontally inside the pump body 1. Furthermore, the fuel discharge port 12a of the discharge connector 12 is connected to the common rail 106.

[0072] When the fuel pressure in the pressurization chamber 11 is lower than the fuel pressure in the discharge valve chamber 1d, the discharge valve 82 is pressed against the discharge valve seat component 81 due to the differential pressure acting on the discharge valve 82 and the force of the discharge valve spring 83. As a result, the discharge valve mechanism 8 is in a closed state. On the other hand, when the fuel pressure in the pressurization chamber 11 becomes greater than the fuel pressure in the discharge valve chamber 1d, and the differential pressure acting on the discharge valve 82 becomes greater than the force of the discharge valve spring 83, the discharge valve 82 is pushed away from the discharge valve seat component 81 by the fuel. As a result, the discharge valve mechanism 8 is in an open state.

[0073] When the discharge valve mechanism 8 performs its opening and closing actions, fuel enters or flows out of the discharge valve chamber 1d. Fuel flowing out of the discharge valve chamber 1d is discharged from the discharge valve mechanism 8 into the discharge passage 1f. As a result, the high-pressure fuel in the pressurization chamber 11 flows through the discharge valve chamber 1d, the discharge passage 1f, and the fuel outlet 12a of the discharge connector 12 to the common rail 106 (see reference). Figure 1 Discharge. According to the above structure, the discharge valve mechanism 8 functions as a check valve to restrict the direction of fuel flow.

[0074] (Fuel pump operation)

[0075] Next, the operation of the high-pressure fuel pump 100 in this embodiment will be explained.

[0076] exist Figure 1 When the plunger 2 is lowered, fuel flows from the intake passage 1a into the pressurization chamber 11 when the electromagnetic intake valve mechanism 3 opens. Hereinafter, the stroke (stroke) during which the plunger 2 lowers will be referred to as the intake stroke. On the other hand, when the plunger 2 is raised, fuel in the pressurization chamber 11 is pressurized when the electromagnetic intake valve mechanism 3 closes, and is then pumped to the common rail 106 (see reference 8) via the discharge valve mechanism 8. Figure 1 Hereinafter, the stroke (stroke) of the piston 2 as it rises will be referred to as the compression stroke.

[0077] As described above, if the electromagnetic intake valve mechanism 3 closes during the compression stroke, the fuel drawn into the pressurization chamber 11 during the intake stroke is pressurized and discharged towards the common rail 106 side. On the other hand, if the electromagnetic intake valve mechanism 3 opens during the compression stroke, the fuel in the pressurization chamber 11 is pushed back to the intake passage 1a side and is not discharged towards the common rail 106 side. In this way, the discharge of fuel from the high-pressure fuel pump 100 is operated by opening and closing the electromagnetic intake valve mechanism 3. Moreover, the opening and closing of the electromagnetic intake valve mechanism 3 is controlled by the ECU 101.

[0078] During the intake stroke, the volume of the pressurized chamber 11 increases, and the fuel pressure within the pressurized chamber 11 decreases. During this intake stroke, the fuel pressure in the pressurized chamber 11 is higher than that at the intake port 31b (reference). Figure 2When the pressure difference between the two exceeds the force of the valve spring 38, the intake valve 32 moves away from the seat 31a, and the electromagnetic intake valve mechanism 3 becomes open. As a result, fuel flows into the pressurization chamber 11 through the multiple holes provided in the stop member 37 between the intake valve 32 and the seat 31a.

[0079] After the high-pressure fuel pump 100 finishes its intake stroke, it transitions to its compression stroke. At this time, the electromagnetic coil 35 remains de-energized, and the magnetic attraction does not act between the anchor 36 and the magnetic core 39. The rod-applying spring 34 is configured to have sufficient force to maintain the intake valve 32 in the open position away from the seat portion 31a when de-energized.

[0080] In this state, even as the plunger 2 moves upward, the rod 33 remains in the open position, and therefore, the suction valve 32, which is exerted by the rod 33, also remains in the open position. Thus, the volume of the pressurization chamber 11 decreases as the plunger 2 moves upward, but in this state, the fuel that was once drawn into the pressurization chamber 11 is returned to the suction channel 10b via the open electromagnetic suction valve mechanism 3, and the pressure inside the pressurization chamber 11 does not rise. This stroke is called the return stroke.

[0081] During the return stroke, when from ECU101 (reference) Figure 1 When the control signal is applied to the electromagnetic suction valve mechanism 3, current flows into the electromagnetic coil 35 through the terminal component 30. When the current flows through the electromagnetic coil 35, the magnetic attraction force acts on the magnetic attraction surface of the magnetic core 39 and the anchor 36, and the anchor 36 is attracted by the magnetic core 39. Moreover, when the magnetic attraction force is greater than the force of the rod force spring 34, the anchor 36 resists the force of the rod force spring 34 and moves towards the magnetic core 39, and the rod 33 engaged with the anchor 36 moves away from the suction valve 32. As a result, due to the force of the valve force spring 38 and the fluid force generated when fuel flows into the suction channel 10b, the suction valve 32 sits in the sitting part 31a, and the electromagnetic suction valve mechanism 3 becomes a closed valve state.

[0082] After the electromagnetic intake valve mechanism 3 is closed, the fuel in the pressurization chamber 11 is pressurized as the plunger 2 rises. When the pressure exceeds that of the fuel discharge 12a, it is discharged through the discharge valve mechanism 8 to the common rail 106 (see reference). Figure 1 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. The amount of high-pressure fuel discharged can be controlled by controlling the timing of energizing the solenoid coil 35 of the solenoid intake valve mechanism 3.

[0083] If the energizing time of the solenoid coil 35 is accelerated, the proportion of the return stroke in the compression stroke decreases, and the proportion of the exhaust stroke increases. As a result, less fuel returns to the intake passage 10b, and more fuel is discharged under high pressure. On the other hand, if the energizing time of the solenoid coil 35 is delayed, the proportion of the return stroke in the compression stroke increases, and the proportion of the exhaust stroke decreases. As a result, more fuel returns to the intake passage 10b, and less fuel is discharged under high pressure. Thus, by controlling the energizing time of the solenoid coil 35, the amount of fuel discharged under high pressure can be controlled to the amount required by the engine (internal combustion engine).

[0084] (cylinder)

[0085] Next, refer to Figures 5-8 Cylinder 6 will be explained.

[0086] Figure 5 This is an exploded perspective view of the high-pressure fuel pump 100. Figure 6 This is a longitudinal cross-sectional view of the area near the cylinder of the high-pressure fuel pump 100. Figure 7 It is an enlarged longitudinal cross-sectional view of the cylinder of the high-pressure fuel pump 100. Figure 8 This is a cross-sectional view of the cylinder of the high-pressure fuel pump 100 when viewed from an oblique angle.

[0087] like Figure 5 As shown, the cylinder 6 is formed as a cylinder with a guide hole 6a extending axially. The cylinder 6 has a large-diameter portion 61, a first small-diameter portion 62, and a second small-diameter portion 63. The large-diameter portion 61 forms the middle portion of the cylinder 6. The first small-diameter portion 62 forms the upper end portion of the cylinder 6, and the second small-diameter portion 63 forms the lower end portion of the cylinder 6.

[0088] The large-diameter portion 61 has an end face 61a at one end (upper end) in the axial direction and an end face 61b at the other end (lower end) in the axial direction. A first small-diameter portion 62 is connected to the end face 61a of the large-diameter portion 61. The first small-diameter portion 62 has an end face 62a at the end opposite to the large-diameter portion 61. The first small-diameter portion 62 and the large-diameter portion 61 are inserted together inside the pump body 1. A second small-diameter portion 63 is connected to the end face 61b of the large-diameter portion 61. The second small-diameter portion 63 is disposed on the outside of the pump body 1.

[0089] like Figure 6 As shown, a cylinder insertion hole 1g is formed in the pump body 1 for inserting a cylinder 6. The cylinder insertion hole 1g is generally cylindrical. The end of the cylinder insertion hole 1g on the pressure chamber 11 side is stepped. Thus, a bottom part 1h of the cylinder insertion hole 1g and an abutment part 1i are provided on the inner side of the pump body 1.

[0090] A pressure chamber forming hole 1j is provided in the center of the bottom part 1h, forming a pressure chamber 11. The pressure chamber forming hole 1j is circular. The center of the pressure chamber forming hole 1j is aligned with the axis of the cylinder insertion hole 1g. The outer diameter of the bottom part 1h is smaller than the outer diameter of the abutment part 1i.

[0091] The end face 62a of the first minor diameter portion 62 of the cylinder 6 is positioned opposite the bottom portion 1h of the cylinder insertion hole 1g with a predetermined gap. In addition, when the plunger 2 is at the bottom dead center, the front end of the plunger 2 (the end face of the major diameter portion 2a) protrudes towards the pressure chamber 11 from the end face 62a of the cylinder 6.

[0092] The end face 61a of the large-diameter portion 61 abuts against the abutting portion 1i. Furthermore, the end face 61b of the large-diameter portion 61 abuts against the aforementioned fixing portion 1c of the pump body 1. End face 61b corresponds to the engaging portion in this invention. The fixing portion 1c is plastically deformed by caulking. The fixing portion 1c presses against the end face 61b of the large-diameter portion 61.

[0093] Next, the pressing part between cylinder 6 and pump body 1, and the clearance between cylinder 6 and pump body 1 will be explained. For example... Figure 7 As shown, the large-diameter portion 61 of the cylinder 6 has a pressing portion 6b. The pressing portion 6b is provided on the outer periphery of the large-diameter portion 61 near the second small-diameter portion 63. That is, the pressing portion 6b is located on the side opposite to the pressure chamber 11 (the lower side) compared to the axial middle portion of the cylinder 6.

[0094] The pressing portion 6b is formed in a continuous circumferential ring on the outer peripheral surface of the large-diameter portion 61 (cylinder 6). The pressing portion 6b of the large-diameter portion 61 abuts against the inner wall surface of the cylinder insertion hole 1g. That is, the pressing portion 6b of the large-diameter portion 61 is pressed into the cylinder insertion hole 1g. As a result, the cylinder 6 can be easily fixed relative to the pump body 1. In addition, the axis of the cylinder 6 can be easily aligned with the axis of the cylinder insertion hole 1g.

[0095] The plunger 2 is movably held by the pump body 1. Therefore, by aligning the axis of the cylinder 6 with the axis of the cylinder insertion hole 1g, the axis of the cylinder 6 can be easily aligned with the axis of the plunger 2. Alternatively, the cylinder 6 can be fixed to the pump body 1 by screws instead of providing the pressing part 6b.

[0096] Furthermore, in cylinder 6, a clearance portion 6c is provided on the side of the specific pressure inlet 6b near the pressurization chamber 11, which has a gap with the pump body 1. The clearance portion 6c is provided on the outer peripheral surface of the specific pressure inlet 6b of the large diameter portion 61 near the pressurization chamber 11 and on the outer peripheral surface of the first small diameter portion 62. The clearance portion 6c is formed in a continuous circumferential ring on the outer peripheral surfaces of the large diameter portion 61 and the first small diameter portion 62.

[0097] Furthermore, a groove 6d is provided on the inner circumferential surface of the cylinder 6 to create a gap with the plunger 2. For example... Figure 7 As shown, the groove 6d is positioned corresponding to the pressing part 6b. That is, the groove 6d is positioned to overlap with the pressing part 6b when viewed radially from the cylinder 6.

[0098] like Figure 7 and Figure 8 As shown, the groove 6d is formed in a continuous circumferential ring on the inner circumferential surface of the cylinder 6. The length of the axial groove 6d of the cylinder 6 is longer than the length of the axial pressing portion 6b of the cylinder 6. In this embodiment, the length of the axial groove 6d of the cylinder 6 is approximately three times the length of the axial pressing portion 6b of the cylinder 6.

[0099] Furthermore, in the axial direction of cylinder 6, the central portion of groove 6d coincides with the central portion of press-in portion 6b. Additionally, groove 6d is located at the middle of the axial direction of cylinder 6. When plunger 2 is at bottom dead center, the front end of plunger 2 (the end face of the large-diameter portion 2a) protrudes towards the pressure chamber side beyond the end face 62a of cylinder 6.

[0100] Fuel is pressurized to a high pressure in the pressurization chamber 11, causing its temperature to rise. As the fuel temperature rises, cylinder 6 thermally expands. Especially in recent years, due to the requirement to discharge high-pressure fuel, the rate of temperature rise has increased. At this time, when the upper part of the outer circumferential surface of cylinder 6 (hereinafter referred to as the "upper outer circumferential surface") contacts the inner circumferential surface of the cylinder insertion hole 1g, the upper part of cylinder 6 deforms due to thermal expansion, and the upper outer circumferential surface of cylinder 6 is pressed against pump body 1. Furthermore, the upper part of the inner circumferential surface of cylinder 6 (hereinafter referred to as the "upper inner circumferential surface") is pressed against plunger 2. As a result, a so-called "fixed" phenomenon occurs, where plunger 2 does not slide.

[0101] In this embodiment, since a gap portion 6c is provided in the cylinder 6, even if the upper part of the cylinder 6 deforms due to thermal expansion, the gap portion 6c can absorb the deformation. As a result, it is possible to prevent the upper outer peripheral surface of the cylinder 6 from being pressed against the inner peripheral surface of the cylinder insertion hole 1g. In addition, the length (distance) of the gap between the cylinder 6 and the pump body 1 generated by the gap portion 6c is determined according to the thermal expansion rate of the cylinder 6 and the temperature of the fuel in the pressurization chamber 11.

[0102] Furthermore, since the upper part of cylinder 6 deforms radially outward with a gap (space), the deformation of the upper inner circumference of cylinder 6 towards the radially inward can be suppressed. This prevents the upper inner circumference of cylinder 6 from being pressed against the outer circumference of plunger 2. Consequently, the phenomenon of plunger 2 becoming stuck can be avoided.

[0103] Considering the deformation of the upper part of cylinder 6 due to thermal expansion, increasing the gap between cylinder 6 and plunger 2 would increase the amount of fuel entering between them. Consequently, the discharge flow rate of the fuel pump would decrease. However, in this embodiment, because the upper part of cylinder 6 deforms radially outward, the gap between cylinder 6 and plunger 2 can be reduced. As a result, a high flow rate of the high-pressure fuel pump 100 can be achieved.

[0104] On the other hand, the pressing portion 6b of cylinder 6 is in contact with pump body 1. Therefore, when cylinder 6 thermally expands, the pressing portion 6b of cylinder 6 is pushed against pump body 1. Therefore, when cylinder 6 thermally expands, deformation of the pressing portion 6b cannot be absorbed radially outward from the cylinder. Therefore, it is impossible to suppress the radially inward deformation of the portion of the inner circumferential surface of cylinder 6 corresponding to the pressing portion 6b (hereinafter referred to as the "inner circumferential surface of the pressing portion"). In addition, the inner circumferential surface of the pressing portion includes a region in the radial direction of cylinder 6 that at least overlaps with the pressing portion 6b.

[0105] In this embodiment, since a groove 6d is provided in the cylinder 6, even if the inner circumferential surface of the pressing part of the cylinder 6 deforms radially inward, the groove 6d can absorb the deformation. Therefore, the inner circumferential surface of the pressing part of the cylinder 6 is prevented from being pressed against the outer circumferential surface of the plunger 2. As a result, the phenomenon of the plunger 2 being fixed can be avoided.

[0106] Furthermore, the thermal expansion area of ​​the inner circumferential surface of the cylinder 6 varies depending on the length of the axial pressing portion 6b of the cylinder 6, the thickness of the cylinder 6 plate in which the pressing portion 6b is provided, and the material of the cylinder 6. Therefore, the length of the axial groove 6d of the cylinder 6 is preferably appropriately set based on the length of the axial pressing portion 6b of the cylinder 6, the thickness of the cylinder 6 plate in which the pressing portion 6b is provided, and the material of the cylinder 6.

[0107] Furthermore, the pressurized portion 6b is located on the opposite side of the cylinder 6's axial direction from the middle portion towards the pressurization chamber 11. In other words, the pressurized portion 6b is located on the opening side of the cylinder insertion hole 1g into which the cylinder 6 is inserted. This allows the pressurized portion 6b to be positioned away from the pressurization chamber 11, making it difficult for the temperature of the fuel within the pressurization chamber 11 to transfer to the pressurized portion 6b. As a result, deformation caused by thermal expansion of the inner circumferential surface of the pressurized portion of the cylinder 6 can be suppressed.

[0108] Furthermore, in this embodiment, a first small-diameter portion 62 is provided on the side of the cylinder 6 closer to the pressure chamber 11 than the large-diameter portion 61. This ensures the sliding distance of the plunger 2 and suppresses fuel flow from the pressure chamber 11 towards the lower part of the plunger 2. Additionally, since the first small-diameter portion 62 is smaller than the large-diameter portion 61, the space required for arranging the cylinder 6 can be reduced. As a result, interference between the cylinder 6 and other components (e.g., the electromagnetic intake valve mechanism 3, the exhaust valve mechanism 8) can be avoided, and the strength of the pump body 1 can be ensured.

[0109] 2. Summary

[0110] As described above, the high-pressure fuel pump 100 (fuel pump) of the above embodiment includes: a reciprocating plunger 2; a cylinder 6, wherein a guide hole 6a (guide hole) for guiding the reciprocating motion of the plunger 2 extends axially; and a pump body 1 (pump body) for holding the cylinder 6. The pump body 1 has: a cylinder insertion hole 1g for inserting the cylinder 6 therein; and a pressurization chamber 11 communicating with the cylinder insertion hole 1g, the volume of which increases or decreases due to the reciprocating motion of the plunger 2. The cylinder 6 has: a pressing portion 6b (pressing portion) pressed into the inner peripheral surface of the cylinder insertion hole 1g; and a groove 6d (groove) formed on the inner peripheral surface of the guide hole 6a at a position corresponding to the pressing portion 6b.

[0111] Therefore, even if the inner circumferential surface of the pressing part of cylinder 6 deforms radially inward, the groove 6d can absorb the deformation. This prevents the inner circumferential surface of the pressing part of cylinder 6 from being pressed against the outer circumferential surface of plunger 2. As a result, the phenomenon of plunger 2 being fixed can be avoided.

[0112] Furthermore, in the high-pressure fuel pump 100 (fuel pump) of the above embodiment, the length of the axial groove 6d (groove) of the cylinder 6 (cylinder) is longer than the length of the axial pressing portion 6b (pressing portion) of the cylinder 6. Therefore, even if the area where the inner circumference of the pressing portion of the cylinder 6 deforms radially inward is longer than the length of the axial pressing portion 6b of the cylinder 6, the groove 6d can absorb the deformation.

[0113] Furthermore, in the high-pressure fuel pump 100 (fuel pump) of the above embodiment, the central portion of the groove 6d (groove) coincides with the central portion of the press-in portion 6b (press-in portion) in the axial direction of the cylinder 6 (cylinder). This allows the groove 6d to be provided in the portion of the cylinder 6 that expands due to heat transferred from the press-in portion 6b. As a result, even if the inner circumferential surface of the press-in portion of the cylinder 6 deforms radially inward, the groove 6d can absorb the deformation.

[0114] Furthermore, in the high-pressure fuel pump 100 (fuel pump) of the above embodiment, the injection section 6b is located lower than the axial center of the cylinder 6 (cylinder) (opposite to the pressurization chamber 11). This allows the injection section 6b to be located away from the pressurization chamber 11, making it difficult for the temperature of the fuel in the pressurization chamber 11 to be transferred to the injection section 6b. As a result, the deformation of the cylinder 6 caused by the thermal expansion of the inner circumferential surface of the injection section can be suppressed.

[0115] Furthermore, in the above-described embodiment, the pressurized portion 6b of the high-pressure fuel pump 100 (fuel pump) is pressed into the inner circumferential surface of the cylinder insertion hole 1g (opposite to the pressurization chamber 11) on the opening side. This allows the pressurized portion 6b to be moved away from the pressurization chamber 11, and makes it difficult for the temperature of the fuel within the pressurization chamber 11 to be transferred to the pressurized portion 6b. As a result, the deformation of the cylinder 6 caused by the thermal expansion of the inner circumferential surface of the pressurized portion can be suppressed.

[0116] Furthermore, the cylinder 6 of the high-pressure fuel pump 100 (fuel pump) in the above embodiment has: a large-diameter portion 61 (large-diameter portion) having an end face 61a (end face) that abuts against an abutment portion 1i (abutment portion) disposed on the inner side of the pump body 1 (pump body); and a first small-diameter portion 62 (small-diameter portion) that is continuous with the end face of the large-diameter portion 61 and extends toward the pressurization chamber 11 (pressurization chamber). This ensures the sliding distance of the plunger 2 (plunger) and suppresses fuel flow from the pressurization chamber 11 toward the lower part of the plunger 2. Additionally, it prevents interference between the cylinder 6 and other components and ensures the strength of the pump body 1.

[0117] Furthermore, in the above-described embodiment, the pressure-in portion 6b of the high-pressure fuel pump 100 (fuel pump) is formed on the outer peripheral surface of the large-diameter portion 61 (large-diameter portion). This allows the pressure-in portion 6b to be positioned away from the pressurization chamber 11 (pressurization chamber). As a result, the temperature of the fuel within the pressurization chamber 11 is less likely to be transferred to the pressure-in portion 6b, thus suppressing the deformation of the cylinder 6 caused by thermal expansion of the inner peripheral surface of the pressure-in portion.

[0118] Furthermore, the cylinder 6 of the high-pressure fuel pump 100 (fuel pump) in the above embodiment has an end face 61b (engaging part) located on the opposite side of the pressure chamber 11 (pressure chamber) from the pressure inlet portion 6b (pressure inlet portion). The pump body 1 (pump body) has a fixing part 1c (fixing part) protruding from the inner circumferential surface of the cylinder insertion hole 1g (cylinder insertion hole). The fixing part 1c presses the end face 61b of the cylinder 6 toward the pressure chamber side. As a result, the cylinder can be reliably fixed to the pump body 1.

[0119] Furthermore, in the above-described embodiment, the fixing part 1c (fixing part) of the high-pressure fuel pump 100 (fuel pump) pushes the end face 61b (engaging part) of the cylinder 6 (cylinder) through plastic deformation. This securely fixes the cylinder 6 to the pump body 1. As a result, high-pressure fuel can be achieved within the pressurization chamber 11.

[0120] The embodiments of the fuel pump of the present invention, including their effects, have been described above. However, the fuel pump of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention as described in the claims. Furthermore, the above-described embodiments are provided for the purpose of readily understanding and illustrating the present invention, and are not intended to limit the scope to include all the structures described.

[0121] For example, in the high-pressure fuel pump 100 of the above embodiment, the length of the axial groove 6d of the cylinder 6 is longer than the length of the axial press-in portion 6b of the cylinder 6. However, as the fuel pump of the present invention, it is sufficient to provide a groove on the inner circumferential surface of the cylinder where it deforms radially inward. Therefore, if the portion of the inner circumferential surface of the cylinder that deforms radially inward is less than or equal to the length of the axial press-in portion of the cylinder 6, the length of the groove can also be set to be less than or equal to the length of the press-in portion.

[0122] Explanation of reference numerals in the attached figures

[0123] 1…Pump body, 1a…Suction passage, 1b…Flange, 1c…Fixing part, 1d…Discharge valve chamber, 1e…Fuel passage, 1f…Discharge passage, 1gCylinder insertion hole, 1h…Bottom part, 1i…Abutting part, 1j…Pressure chamber forming hole, 2…Plug, 3…Electromagnetic suction valve mechanism, 4…Overflow valve mechanism, 5…Suction connector, 6Cylinder, 6a…Guide hole, 6b…Pressing part. 6c…gap section, 6d…groove, 8…exhaust valve mechanism, 9…metal damper, 10…low-pressure fuel chamber, 11…pressurization chamber, 12…exhaust connector, 51…low-pressure fuel inlet, 61…large diameter section, 61a, 61b…end face, 62…first small diameter section, 62a…end face, 63…second small diameter section, 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, 200…fuel supply system.

Claims

1. A fuel pump, characterized in that, include: A plunger that reciprocates; A cylinder, wherein a guide hole for guiding the reciprocating motion of the plunger extends axially; and The pump body of the cylinder has a cylinder insertion port into which the cylinder is inserted and a pressurization chamber communicating with the cylinder insertion port, the volume of which increases or decreases due to the reciprocating motion of the plunger. The cylinder has: a press-in portion that contacts the inner circumferential surface of the cylinder insertion hole; and a groove formed on the inner circumferential surface of the guide hole at a position corresponding to the press-in portion. The press-in portion is formed in a continuous circumferential ring on the outer peripheral surface of the cylinder. The groove is positioned to overlap with the press-in portion when viewed radially from the cylinder, and the groove is formed in a continuous circumferential annular shape on the inner circumferential surface of the cylinder. The groove is longer in the axial direction of the cylinder than the press-in portion is in the axial direction of the cylinder. In the axial direction of the cylinder, the central portion of the groove coincides with the central portion of the press-in portion.

2. The fuel pump as claimed in claim 1, characterized in that: The pressing part is located at the lower side of the middle part of the cylinder in the axial direction.

3. The fuel pump as claimed in claim 1, characterized in that: The pressing part is pressed into the inner circumferential surface on the opening side of the cylinder insertion hole.

4. The fuel pump as claimed in claim 1, characterized in that: The cylinder has a large-diameter portion and a small-diameter portion. The large-diameter portion has an end face that abuts against a contact portion disposed on the inner side of the pump body. The small-diameter portion is connected to the end face of the large-diameter portion and extends toward the pressurization chamber.

5. The fuel pump as claimed in claim 4, characterized in that, The press-in portion is formed on the outer peripheral surface of the large-diameter portion.

6. The fuel pump as claimed in claim 1, characterized in that: The cylinder has an engaging portion located on the opposite side of the pressurization chamber than the pressing portion. The pump body has a fixing part that protrudes from the inner circumferential surface of the cylinder insertion hole. The fixing part pushes the locking part of the cylinder toward the pressurization chamber side.

7. The fuel pump as claimed in claim 6, characterized in that: The fixing part pushes the engaging part of the cylinder through plastic deformation.

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