Fuel pump

Abstract

Provided is a fuel pump capable of discharging fuel at high pressure and capable of suppressing sticking of a plunger to a cylinder. The high-pressure fuel supply pump includes a plunger that performs reciprocating motion; a cylinder whose guide hole that guides the reciprocating motion of the plunger extends in the axial direction; and a pump main body having a third chamber (cylinder insertion hole) into which the cylinder is pressed, and a pressurizing chamber that increases and decreases in volume by the reciprocating motion of the plunger, which communicates with the third chamber. The pressure of a fixed gap generated between the cylinder and the pump main body is set to be equal to or higher than the pressure of a sliding gap generated between the plunger and the cylinder.

Description

Technical Field

[0001] This invention relates to a fuel pump that supplies fuel to an engine under high pressure. Background Technology

[0002] As a fuel pump, for example, there is a structure described in Patent Document 1. The high-pressure fuel supply pump described in Patent Document 1 has a housing, a suction valve, a discharge valve, and a pressure reducing valve. The housing has a cylinder, which is a stepped, cylindrical space that houses a cylinder liner that slidably holds a plunger and forms a pressure chamber. The suction valve is open when no current is supplied to the solenoid, and opens when current is supplied to the solenoid to draw fuel into the pressure chamber.

[0003] The discharge valve is installed in the discharge valve housing of the housing, which is connected to the pressurization chamber via a fuel discharge port. High-pressure fuel, pressurized in the pressurization chamber, is supplied to the discharge valve. The discharge valve opens when the pressure of the supplied fuel reaches a specified pressure, and the fuel passing through the discharge valve is forced into the accumulator.

[0004] Additionally, the pressure reducing valve is assembled in the pressure reducing valve housing of the housing. The pressure reducing valve housing is connected to the high-pressure area downstream of the discharge valve and is also connected to the pressurization chamber via a connecting passage. The pressure reducing valve opens when the fuel pressure in the high-pressure area reaches a certain pressure, allowing the high-pressure fuel to flow back to the pressurization chamber.

[0005] The high-pressure fuel supply pump described in Patent Document 1 is configured such that the flat portion of the cylinder is pushed by the flat portion of the main body. Hereinafter, the part that pushes the flat portion of the cylinder to the flat portion of the main body will be referred to as the "flat pushing portion".

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2018 / 186219 Summary of the Invention

[0009] The technical problem that the invention aims to solve

[0010] However, the sealing performance of the face-pressing section is unstable. That is, some units (high-pressure fuel supply pumps) can prevent fuel from entering (passing through), while others (high-pressure fuel supply pumps) cannot. Moreover, even the same unit (high-pressure fuel supply pump) may sometimes be able to prevent fuel from entering (passing through) and sometimes not, depending on the operating conditions and environment.

[0011] When the pressure in the pressurization chamber (hereinafter referred to as "pressurization chamber pressure") is high, the pressure at the end of the pressurization chamber side in the tiny sliding gap between the plunger and the cylinder becomes the same as the pressurization chamber pressure. The pressure in the sliding gap gradually decreases as it moves towards the opposite side of the pressurization chamber side, becoming low pressure (the same pressure as the auxiliary chamber) at the end of the opposite side of the pressurization chamber side.

[0012] When the piston and cylinder body's surface pressing section can completely seal the fuel, the pressure in the pressurized chamber cannot reach the outer circumferential surface of the cylinder. Consequently, the pressure in the sliding clearance between the plunger and cylinder is higher than the pressure on the outer circumferential surface of the cylinder. This causes the sliding clearance to widen, increasing fuel leakage. As a result, the amount of high-pressure fuel discharged is low, or the volumetric efficiency is low, leading to the primary problem of not being able to discharge the amount of fuel required by the engine at high pressure. To solve this primary problem, the sliding clearance needs to be reduced.

[0013] On the other hand, if the fuel cannot be completely sealed by the pressure-pressing part between the cylinder and the body, the pressure in the pressurized chamber reaches the outer circumferential surface of the cylinder. As a result, the pressure in the sliding clearance between the plunger and the cylinder is lower than the pressure on the outer circumferential surface of the cylinder. Consequently, the sliding clearance becomes smaller, or even zero, leading to a second problem: plunger-cylinder adhesion. Even when the sliding clearance is reduced to ensure high-pressure discharge flow, the plunger and cylinder become more prone to adhesion.

[0014] As described above, due to the unstable sealing performance of the face pressing part, there is a situation where one part experiences the first problem while another part experiences the second problem. Furthermore, even for the same part, there is a situation where the first problem occurs under certain conditions and the second problem occurs under other conditions.

[0015] The purpose of this invention is to address the aforementioned problems by providing a fuel pump capable of discharging fuel at high pressure and suppressing piston-cylinder adhesion.

[0016] Technical solutions for solving the problem

[0017] To address the aforementioned issues and achieve the objectives of this invention, the fuel pump of this invention comprises: a plunger that reciprocates; a cylinder, wherein a guide hole for guiding the reciprocating motion of the plunger extends axially; and a pump body having a cylinder insertion hole into which the cylinder is pressed, and a pressurization chamber communicating with the cylinder insertion hole and whose volume increases or decreases due to the reciprocating motion of the plunger. The pressure of the fixed gap generated between the cylinder and the pump body is set to be equal to or greater than the pressure of the sliding gap generated between the plunger and the cylinder.

[0018] Invention Effects

[0019] The fuel pump with the above structure can discharge fuel at high pressure and can suppress the sticking of the plunger to the cylinder.

[0020] Furthermore, the issues, structures, and effects other than those mentioned above will become clearer through the following description of the implementation methods. Attached Figure Description

[0021] Figure 1 This is an overall structural diagram of a fuel supply system using a high-pressure fuel supply pump according to the first embodiment of the present invention.

[0022] Figure 2 This is a longitudinal cross-sectional view (one of) of the high-pressure fuel supply pump according to the first embodiment of the present invention.

[0023] Figure 3 This is a longitudinal cross-sectional view (second of the first embodiment) of the high-pressure fuel supply pump of the present invention.

[0024] Figure 4 This is a longitudinal cross-sectional view (third of three) of the high-pressure fuel supply pump according to the first embodiment of the present invention.

[0025] Figure 5 This is a horizontal cross-sectional view of the high-pressure fuel supply pump according to the first embodiment of the present invention, viewed from above.

[0026] Figure 6 This is an explanatory diagram showing an enlarged view of the pressurization chamber in the high-pressure fuel supply pump according to the first embodiment of the present invention.

[0027] Figure 7 This is a perspective view of the cylinder of the high-pressure fuel supply pump according to the first embodiment of the present invention.

[0028] Figure 8 This is a perspective view of the cylinder of the high-pressure fuel supply pump according to the second embodiment of the present invention. Detailed Implementation

[0029] 1. First Implementation Method

[0030] The high-pressure fuel supply pump according to the first embodiment of the present invention will be described below. Furthermore, common components are labeled with the same reference numerals in all figures.

[0031] [Fuel Supply System]

[0032] Next, the fuel supply system using the high-pressure fuel supply pump (fuel pump) of this embodiment is further described using... Figure 1 Please provide an explanation.

[0033] Figure 1 This is an overall structural diagram of a fuel supply system using the high-pressure fuel supply pump of this embodiment.

[0034] like Figure 1As shown, the fuel supply system includes a high-pressure fuel supply pump (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 supply pump 100 are assembled as one unit with the pump body 1.

[0035] Fuel in fuel tank 103 is drawn by feed pump 102, which is driven by a signal from ECU 101. The drawn fuel is pressurized to an 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 supply pump 100.

[0036] A high-pressure fuel supply 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 accordance with the number of cylinders (combustion chambers) and inject fuel according to 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 directly inject fuel into the cylinders of the engine.

[0037] The fuel pressure sensor 105 outputs the detected pressure data to the ECU 101. The ECU 101 calculates the appropriate fuel injection quantity (target fuel injection length) and the appropriate fuel pressure (target fuel pressure) based on engine state quantities (such as crankshaft rotation angle, throttle valve opening, engine speed, fuel pressure, etc.) obtained from various sensors.

[0038] Furthermore, the ECU 101 controls the driving of the high-pressure fuel supply pump 100 and the multiple injectors 107 based on calculations such as fuel pressure (target fuel pressure). That is, the ECU 101 has a pump control unit that controls the high-pressure fuel supply pump 100 and an injector control unit that controls the injectors 107.

[0039] The high-pressure fuel supply pump 100 includes a pressure pulsation reduction mechanism 9, an electromagnetic suction valve mechanism 3 as a variable capacity mechanism, and a pressure reducing valve mechanism 4 (see reference). Figure 2 ) and discharge valve mechanism 8. Fuel flowing in from low-pressure fuel inlet 51 reaches the intake port 31b of electromagnetic intake valve mechanism 3 via pressure pulsation reduction mechanism 9 and intake passage 10b.

[0040] Fuel flowing into the electromagnetic intake valve mechanism 3 passes through the valve section 32, flows through the intake passage 1d formed in the pump body 1, and then flows into the pressurization chamber 11. A plunger 2 is reciprocatingly inserted into the pressurization chamber 11. The plunger 2 is controlled by the engine cam 91 (see reference). Figure 2 It transmits power to carry out reciprocating motion.

[0041] In the pressurization chamber 11, fuel is drawn in from the electromagnetic intake valve mechanism 3 during the downward stroke of the plunger 2, and pressurized during the upward stroke. When the fuel pressure in the pressurization chamber 11 exceeds a specified value, the discharge valve mechanism 8 opens, and the high-pressure fuel is pumped to the common rail 106 via the discharge passage 12a. The discharge of fuel from the high-pressure fuel supply pump 100 is operated by opening and closing the electromagnetic intake valve mechanism 3. The opening and closing of the electromagnetic intake valve mechanism 3 is controlled by the ECU 101.

[0042] [High-pressure fuel supply pump]

[0043] Next, the structure of the high-pressure fuel supply pump 100 is utilized. Figures 2-6 Please provide an explanation.

[0044] Figure 2 This is one of the longitudinal cross-sectional views of the high-pressure fuel supply pump 100 viewed from a section orthogonal to the horizontal direction. Figure 3 This is a longitudinal section view (part two) of the high-pressure fuel supply pump 100, viewed from a section orthogonal to the horizontal direction. Figure 4 This is a horizontal cross-sectional view of the high-pressure fuel supply pump 100, taken from a section orthogonal to the vertical direction. Figure 5 This is a longitudinal section view (part three) of the high-pressure fuel supply pump 100, viewed from a section orthogonal to the horizontal direction. Figure 6 This is an explanatory diagram showing the pressure reducing valve mechanism 4 in an enlarged form.

[0045] like Figure 2 As shown, the pump body 1 of the high-pressure fuel supply pump 100 is formed in a generally cylindrical shape. Figure 2 and Figure 3 As shown, the pump body 1 has a first chamber 1a, a second chamber 1b, a third chamber 1c, and a suction passage 1d inside. Furthermore, the pump body 1 is tightly attached to the fuel pump mounting part 90 and is secured by a plurality of bolts (screws) not shown.

[0046] The first chamber 1a is a cylindrical space provided in the pump body 1, and the center line 1A of the first chamber 1a is aligned with the center line of the pump body 1. One end of the plunger 2 is inserted into the first chamber 1a, and the plunger 2 reciprocates within the first chamber 1a. The first chamber 1a and one end of the plunger 2 form a pressurization chamber 11.

[0047] The second chamber 1b is a cylindrical space within the pump body 1, and its centerline is orthogonal to the centerline of the pump body 1 (first chamber 1a). A pressure-reducing valve chamber, housing the pressure-reducing valve mechanism 4, is formed within this second chamber 1b. Furthermore, the diameter of the second chamber 1b (pressure-reducing valve chamber) is smaller than that of the first chamber 1a. The first chamber 1a and the second chamber 1b are connected by a circular connecting hole 1e. Fuel that has passed through the pressure-reducing valve mechanism 4 returns to the pressurization chamber 11 through the connecting hole 1e.

[0048] The third chamber 1c is a cylindrical space provided in the pump body 1, continuous with 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 the diameter of the first chamber 1a. A cylinder 6, which guides the reciprocating motion of the plunger 2, is disposed in the third chamber 1c. As a result, the end face of the cylinder 6 can abut against the stepped portion (flat portion) between the first chamber 1a and the third chamber 1c, preventing the cylinder 6 from shifting towards the first chamber 1a.

[0049] Cylinder 6 is cylindrical, and its outer circumference is pressed into the third chamber 1c of pump body 1. One end of cylinder 6 abuts against the top surface of the third chamber 1c (the step between the first chamber 1a and the third chamber 1c). Plunger 2 is slidably in contact with the inner circumferential surface of cylinder 6. For detailed information on the shape of cylinder 6 and the method of fixing it to pump body 1, please refer to [reference needed]. Figure 7 Further explanation is provided below.

[0050] Within the pump body 1, a fixing part 1x is provided that engages approximately at the center of the cylinder 6 along its axial direction. The fixing part 1x is capable of plastic deformation. The fixing part 1x pulls the cylinder 6 upwards ( Figure 2 (Push from above)

[0051] An O-ring 93, representing a specific example of a sealing component, is inserted 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) by passing between the fuel pump mounting portion 90 and the pump body 1.

[0052] A tappet 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, which is transmitted to the plunger 2. The plunger 2 is pressed against the tappet 92 by the spring 16 via the retainer 15. The tappet 92 reciprocates along with the rotation of the cam 91. The reciprocating motion of the plunger 2 and the tappet 92 together causes the volume of the pressure chamber 11 to change.

[0053] Additionally, a sealing retainer 17 is disposed between the cylinder 6 and the support member 15. The sealing retainer 17 is formed into a cylindrical shape into which the plunger 2 can be inserted, and has a secondary chamber 17a at the upper end on the cylinder 6 side. Furthermore, the sealing retainer 17 retains the plunger seal 18 at the lower end on the support member 15 side.

[0054] The plunger seal 18 is slidably in contact with the outer periphery of the plunger 2. When the plunger 2 reciprocates, it seals the fuel in the secondary chamber 17a, preventing the fuel in the secondary 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 interior of the pump body 1.

[0055] 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.

[0056] 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.

[0057] Sub-chamber 17a is connected to fuel passage 10c (see reference). Figure 5 It is connected to the low-pressure fuel chamber 10. When the plunger 2 descends, fuel flows from the auxiliary chamber 17a to the low-pressure fuel chamber 10, and when the plunger 2 rises, fuel flows from the low-pressure fuel chamber 10 to the auxiliary chamber 17a. This reduces the fuel flow to and from the pump during the suction or return stroke of the high-pressure fuel supply pump 100, and reduces pressure pulsations generated inside the high-pressure fuel supply pump 100.

[0058] like Figure 3 As shown, a low-pressure fuel chamber 10 is provided on the upper part of the pump body 1 of the high-pressure fuel supply pump 100, and a suction connector 5 is installed on the side of the pump body 1. The suction connector 5 is connected to the fuel tank 103 (see reference 103) to allow fuel to flow from the fuel tank 103. Figure 1 The fuel supplied passes through the low-pressure piping 104. Fuel from the fuel tank 103 is supplied to the interior of the pump body 1 from the suction connector 5.

[0059] The suction connector 5 has a low-pressure fuel inlet 51 connected to the low-pressure piping 104 and a suction flow path 52 communicating with the low-pressure fuel inlet 51. Fuel passing through the suction flow path 52 is supplied to the low-pressure fuel chamber 10 through a suction filter 53 disposed inside the pump body 1. The suction filter 53 removes foreign matter present in the fuel, preventing foreign matter from entering the high-pressure fuel supply pump 100.

[0060] The low-pressure fuel chamber 10 is provided with a low-pressure fuel flow path 10a and an intake passage 10b (see reference). Figure 2 A pressure pulsation reduction mechanism 9 is provided in the low-pressure fuel flow path 10a. When fuel flowing into the pressurization chamber 11 returns to the suction passage 10b through the electromagnetic suction valve mechanism 3 in the open state, pressure pulsation occurs in the low-pressure fuel chamber 10. The pressure pulsation reduction mechanism 9 reduces the impact of the pressure pulsation generated in the high-pressure fuel supply pump 100 on the low-pressure piping 104.

[0061] The pressure pulsation reduction mechanism 9 is formed by a metal diaphragm damper in which two corrugated disc-shaped metal plates are attached to its outer periphery and an inactive gas such as argon is injected inside. The metal diaphragm damper of the pressure pulsation reduction mechanism 9 absorbs or reduces pressure pulsations through expansion and contraction.

[0062] Inhalation passage 10b and inhalation port 31b of electromagnetic inhalation valve mechanism 3 (see reference) Figure 2 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.

[0063] 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 on the upstream side of the pressurization chamber 11 (suction passage 10b side) and is formed as a horizontal hole extending in the horizontal direction. The electromagnetic suction valve mechanism 3 has a suction valve seat 31, a valve part 32, a rod 33, a rod force spring 34, an electromagnetic coil 35, and an armature 36 that are pressed into the suction valve chamber 30.

[0064] The intake valve seat 31 is cylindrical, and a seating portion 31a is provided on its inner periphery. Additionally, an intake port 31b is formed on the intake valve seat 31, extending from the outer periphery to the inner periphery. This intake port 31b communicates with the intake passage 10b in the aforementioned low-pressure fuel chamber 10.

[0065] A stop member 37 is provided in the suction valve chamber 30, opposite to the seating portion 31a of the suction valve seat 31. A valve portion 32 is disposed between the stop member 37 and the seating portion 31a. In addition, a valve force spring 38 is provided between the stop member 37 and the valve portion 32. The valve force spring 38 applies force to the valve portion 32 toward the seating portion 31a.

[0066] The valve section 32 abuts against the seat section 31a, thereby locking the connection between the suction port 31b and the pressurization chamber 11. When the valve section 32 locks the connection between the suction port 31b and the pressurization chamber 11, the electromagnetic suction valve mechanism 3 is in the closed state. On the other hand, the valve section 32 abuts against the stop member 37, opening the connection between the suction port 31b and the pressurization chamber 11. When the valve section 32 opens the connection between the suction port 31b and the pressurization chamber 11, the electromagnetic suction valve mechanism 3 is in the open state.

[0067] Rod 33 passes through the cylindrical hole of the suction valve seat 31, and one end abuts against the valve part 32. Rod force spring 34 applies force to valve part 32 towards the stop member 37, i.e., in the valve opening direction, via rod 33. One end of rod force spring 34 engages with the other end of rod 33, and the other end of rod force spring 34 engages with magnetic core 39 arranged in a manner that surrounds rod force spring 34.

[0068] The end faces of the armature 36 and the magnetic core 39 are opposite each other. Furthermore, the armature 36 engages with a flange located in the middle of the rod 33. The electromagnetic coil 35 is arranged to wrap around the magnetic core 39. A terminal component 40 is electrically connected to the electromagnetic coil 35, through which current flows.

[0069] In the de-energized state where no current flows through the electromagnetic coil 35, the rod 33 is forced in the valve-opening direction by the force generated by the rod-applying spring 34, pushing the valve part 32 in the valve-opening direction. As a result, the valve part 32 separates from the seat part 31a and abuts against the stop member 37, and the electromagnetic suction valve mechanism 3 becomes open. That is, the electromagnetic suction valve mechanism 3 is a normally open type that opens the valve in the de-energized state.

[0070] In the open state of the electromagnetic suction valve mechanism 3, fuel at the suction port 31b passes between the valve section 32 and the seat section 31a, flowing into the pressurization chamber 11 through multiple fuel passage holes (not shown) of the stop member 37 and the suction passage 1d. In the open state of the electromagnetic suction valve mechanism 3, the position of the valve section 32 in the opening direction is restricted because the valve section 32 is in contact with the stop member 37. The gap between the valve section 32 and the seat section 31a in the open state of the electromagnetic suction valve mechanism 3 is the movable range of the valve section 32, and is considered as the opening stroke.

[0071] When current flows through the electromagnetic coil 35, the armature 36 is attracted towards the closing valve direction by the magnetic attraction of the magnetic core 39. As a result, the armature 36 moves against the force of the lever spring 34 and comes into contact with the magnetic core 39. When the armature 36 moves towards the magnetic core 39, i.e., towards the closing valve direction, the lever 33 engaged by the armature 36 moves together with the armature 36. As a result, the valve part 32 is released from the force in the opening valve direction and moves towards the closing valve direction by the force generated by the valve force spring 38. When the valve part 32 comes into contact with the seat portion 31a of the suction valve seat 31, the electromagnetic suction valve mechanism 3 is in the closed valve state.

[0072] like Figure 4 and Figure 5 As shown, the discharge valve mechanism 8 is disposed in the discharge valve chamber 80 located on the outlet side (downstream side) of the pressurization chamber 11. The discharge valve mechanism 8 includes: a discharge valve seat 81 communicating with the pressurization chamber 11; a valve portion 82 that contacts and separates from the discharge valve seat 81; a discharge valve spring 83 that applies force to the valve portion 82 toward the discharge valve seat 81; and a discharge valve stop 84 that determines the stroke (travel distance) of the valve portion 82.

[0073] Additionally, the discharge valve mechanism 8 has a plug 85 that prevents fuel leakage to the outside. A discharge valve stop 84 is pressed into the plug 85. The plug 85 is engaged with the pump body 1 by welding at a weld joint 86. The discharge valve chamber 80 is opened and closed via a valve section 82. This discharge valve chamber 80 communicates with a discharge valve chamber passage 87. The discharge valve chamber passage 87 is formed in the pump body 1.

[0074] A device is provided in the pump body 1 that is similar to Figure 2 The discharge connector 12 is inserted into a transverse hole that communicates with the second chamber 1b (pressure reducing valve chamber). The discharge connector 12 has a discharge passage 12a that communicates with the transverse hole of the pump body 1 and the discharge valve chamber passage 87, and a fuel outlet 12b as one end of the discharge passage 12a. The fuel outlet 12b of the discharge connector 12 communicates with the common rail 106. Furthermore, the discharge connector 12 is fixed to the pump body 1 by welding with a welded part 12c.

[0075] When there is no fuel pressure difference (fuel differential pressure) between the pressurization chamber 11 and the discharge valve chamber 80 (discharge valve chamber passage 87), the valve part 82 is pressed against the discharge valve seat 81 by the force of the discharge valve spring 83, and the discharge valve mechanism 8 is in the closed state. When the fuel pressure in the pressurization chamber 11 is greater than the fuel pressure in the discharge valve chamber 80 (discharge valve chamber passage 87), the valve part 82 moves against the force of the discharge valve spring 83, and the discharge valve mechanism 8 is in the open state.

[0076] When the discharge valve mechanism 8 is in the open position, the (high-pressure) fuel in the pressurized chamber 11 reaches the discharge valve chamber 80 (discharge valve chamber passage 87) through the discharge valve mechanism 8. The fuel reaching the discharge valve chamber passage 87 flows through the fuel discharge port 12b of the discharge connector 12 to the common rail 106 (see reference). Figure 1 Discharge. Based on the above structure, the discharge valve mechanism 8 functions as a check valve to restrict the direction of fuel flow.

[0077] Figure 2 and Figure 6 The pressure reducing valve mechanism 4 shown is configured such that it actuates when problems arise in the common rail 106 and subsequent components, causing the common rail 106 to exceed a predetermined pressure and become high, thus returning fuel in the discharge passage 12a to the pressurization chamber 11. The discharge passage 12a is connected to the discharge valve chamber 80 via the discharge valve chamber passage 87. Therefore, the pressure in the discharge passage 12a is equal to the pressure in the discharge valve chamber 80.

[0078] The pressure reducing valve mechanism 4 becomes open when the pressure difference between the discharge valve chamber 80 (discharge valve chamber passage 87) and the pressure in the second chamber 1b (pressure reducing valve chamber) exceeds a set value.

[0079] The pressure reducing valve mechanism 4 includes a pressure reducing spring 41, a pressure reducing valve retainer 42, a pressure reducing valve 43, and a valve seat assembly 44. This pressure reducing valve mechanism 4 is inserted through the discharge connector 12 and disposed in the second chamber 1b (pressure reducing valve chamber). The pressure reducing spring 41 is a helical spring, with one end abutting against the pump body 1 (one end of the second chamber 1b). The other end of the pressure reducing spring 41 abuts against the pressure reducing valve retainer 42. The pressure reducing valve retainer 42 engages with the pressure reducing valve 43, and the force of the pressure reducing spring 41 acts on the pressure reducing valve 43 via the pressure reducing valve retainer 42.

[0080] The pressure reducing valve retainer 42 has an abutment portion 42a and a through portion 42b continuous with the abutment portion 42a. The abutment portion 42a is formed as a circular plate with an appropriate thickness. An engagement groove for engaging the pressure reducing valve 43 is formed on one plane of the abutment portion 42a. The through portion 42b protrudes from another plane of the abutment portion 42a, and the other end of the pressure reducing spring 41 abuts against the other plane of the abutment portion 42a. The through portion 42b is cylindrical and is inserted into the radially inner side of the pressure reducing spring 41.

[0081] When compressed, the pressure-reducing spring 41 is located between one end of the second chamber 1b (around the suction passage 1d described later) and the abutment portion 42a of the pressure-reducing valve retainer 42, and the compression applies force to the pressure-reducing valve retainer 42 and the pressure-reducing valve 43 toward the valve seat component 44.

[0082] The pressure reducing valve 43 is pushed by the force of the pressure reducing spring 41, blocking the fuel passage of the valve seat component 44. The direction of movement of the pressure reducing valve 43 (pressure reducing valve holder 42) is orthogonal to the direction of reciprocating motion of the plunger 2, and is the same as the direction of movement of the valve part (suction valve) 32 in the electromagnetic suction valve mechanism 3.

[0083] The valve seat component 44 has a fuel passage opposite to the pressure reducing valve 43, the opposite side of which is connected to the discharge passage 12a. The movement of fuel between the pressurized chamber 11 (upstream side) and the valve seat component 44 (downstream side) is blocked by the pressure reducing valve 43 contacting (pressurizing) the valve seat component 44, thus blocking the fuel passage.

[0084] When the pressure in the discharge valve chamber 80 (discharge valve chamber passage 87) and the common rail 106, and the subsequent components, increases, the pressure difference with the second chamber 1b (pressure reducing valve chamber) exceeds a set value. As a result, the fuel on the valve seat component 44 pushes the pressure reducing valve 43 against the force of the pressure reducing spring 41, causing the pressure reducing valve 43 to move. Consequently, the pressure reducing valve 43 opens, and the fuel in the discharge passage 12a returns to the pressurized chamber 11 through the fuel passage of the valve seat component 44. Thus, the pressure that causes the pressure reducing valve 43 to open is determined by the force of the pressure reducing spring 41.

[0085] [Operation of the high-pressure fuel pump]

[0086] Next, regarding the operation of the high-pressure fuel pump in this embodiment, using... Figure 2 , Figure 4 Please provide an explanation.

[0087] exist Figure 2 In the case where the plunger 2 is descending, when the electromagnetic suction valve mechanism 3 opens, fuel flows from the suction passage 1d into the pressurization chamber 11. Hereinafter, the stroke of the plunger 2 descending will be referred to as the suction stroke. On the other hand, when the plunger 2 is ascending, when the electromagnetic suction valve mechanism 3 closes, the fuel in the pressurization chamber 11 is pressurized and discharged through the discharge valve mechanism 8 (see reference 8). Figure 4 Towards common orbit 106 (reference) Figure 1 It is compressed. Hereinafter, the process of the plunger 2 rising will be referred to as the rising stroke.

[0088] As described above, if the electromagnetic intake valve mechanism 3 closes during the upward 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 upward stroke, the fuel in the pressurization chamber 11 is pushed back towards the intake passage 1d side, instead of being discharged towards the common rail 106 side. In this way, the discharge of fuel by the high-pressure fuel supply pump 100 is operated 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.

[0089] During the intake stroke, the volume of the pressurized chamber 11 increases, and the fuel pressure within the pressurized chamber 11 decreases. As a result, the fluid differential pressure between the intake port 31b and the pressurized chamber 11 (hereinafter referred to as the "fluid differential pressure before and after the valve section 32") decreases. When the force of the lever-applying spring 34 is greater than the fluid differential pressure before and after the valve section 32, the lever 33 moves in the valve-opening direction, the valve section 32 moves away from the seat portion 31a of the intake valve seat 31, and the electromagnetic intake valve mechanism 3 enters the open state.

[0090] When the electromagnetic suction valve mechanism 3 is in the open state, fuel from the suction port 31b flows into the pressurization chamber 11 through the valve part 32 and the seat part 31a, and through multiple fuel passage holes (not shown) of the stop member 37, from the suction passage 1d or the supply communication hole 1g. In the open state of the electromagnetic suction valve mechanism 3, the valve part 32 is in contact with the stop member 37, thus restricting the position of the valve part 32 in the opening direction. The gap between the valve part 32 and the seat part 31a in the open state of the electromagnetic suction valve mechanism 3 is the movable range of the valve part 32, which is called the opening stroke.

[0091] After the intake stroke ends, the process transitions to the rising stroke. At this time, the electromagnetic coil 35 remains de-energized, and there is no magnetic attraction between the armature 36 and the magnetic core 39. For the valve section 32, the force acting in the opening direction corresponds to the difference in force between the rod force spring 34 and the valve force spring 38, and the force acting in the closing direction is caused by the fluid force generated when fuel flows counter-currently from the pressurized chamber 11 to the low-pressure fuel flow path 10a.

[0092] In this state, to maintain the open valve position, the electromagnetic suction valve mechanism 3 sets the difference in force between the rod force spring 34 and the valve force spring 38 to be greater than the fluid force. The volume of the pressurization chamber 11 decreases as the plunger 2 rises. Therefore, the fuel sucked into the pressurization chamber 11 returns to the suction port 31b through the valve section 32 and the seat section 31a, and the pressure inside the pressurization chamber 11 does not rise. This stroke is called the return stroke.

[0093] During the return journey, from ECU101 (reference) Figure 1 When a control signal is applied to the electromagnetic suction valve mechanism 3, current flows through the terminal component 40 into the electromagnetic coil 35. When current flows through the electromagnetic coil 35, a magnetic attraction force is exerted between the magnetic core 39 and the armature 36, causing the armature 36 (rod 33) to be attracted towards the magnetic core 39. As a result, the armature 36 (rod 33) moves against the force generated by the rod-applying spring 34 in the valve-closing direction (the direction away from the valve section 32).

[0094] When the armature 36 (rod 33) moves toward the closing valve direction, the valve part 32 is released from the force acting in the opening valve direction, and moves toward the closing valve direction by the force generated by the valve force spring 38 and the fluid force generated by the fuel flowing into the suction passage 10b. When the valve part 32 contacts the sitting part 31a of the suction valve seat 31 (the valve part 32 sits on the sitting part 31a), the electromagnetic suction valve mechanism 3 becomes the closed valve state.

[0095] After the electromagnetic intake valve mechanism 3 is in the closed state, the fuel in the pressurization chamber 11 is pressurized as the plunger 2 rises. When the pressure reaches a specified level, it is discharged through the discharge valve mechanism 8 to the common rail 106 (see reference). Figure 1 The discharge stroke is referred to as the discharge stroke. That is, the upward 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.

[0096] If the timing of energizing the solenoid coil 35 is advanced, the proportion of the return stroke in the rising 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 discharged under high pressure. Conversely, if the timing of energizing the solenoid coil 35 is delayed, the proportion of the return stroke in the rising 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 discharged under high pressure. In this way, by controlling the timing of energizing 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).

[0097] [The shape of the tank]

[0098] Next, regarding the shape of cylinder 6 in this embodiment, using... Figure 7 Please provide an explanation.

[0099] Figure 7 This is a 3D view of cylinder 6.

[0100] like Figure 7 As shown, cylinder 6 is formed as a cylinder with a guide hole 6a extending in the axial direction. Cylinder 6 has a large-diameter portion 61 that is continuous in the axial direction and a small-diameter portion 62 that is smaller in diameter than the large-diameter portion 61. The large-diameter portion 61 forms the upper part of cylinder 6, and the small-diameter portion 62 forms the lower part of cylinder 6.

[0101] The large-diameter portion 61 has an end face 61a as one end (upper end) and an end face 61b as the other end (lower end) as the axial direction. The large-diameter portion 61 is inserted into the pump body 1 (see reference). Figure 2 The small diameter portion 62 is continuous with the end face 61b of the large diameter portion 61. The small diameter portion 62 is disposed on the outside of the pump body 1.

[0102] The end face 61a of the large-diameter portion 61 is formed in an annular shape. The end face 61a is aligned with the pump body 1 (see reference). Figure 2 The step portion (hereinafter referred to as "bottom surface of third chamber 1c") between the first chamber 1a and the third chamber 1c in the cylinder 6 abuts against each other. A connecting passage 63 is provided on the end face 61a. The connecting passage 63 is formed as a groove extending radially in the large diameter portion 61. The connecting passage 63 is set to a length from the inner circumferential surface 61c of the large diameter portion 61 to the outer circumferential surface 61d. When the cylinder 6 is fixed to the pump body 1, the gap between the outer circumferential surface 61d of the cylinder 6 and the pump body 1 is connected to the pressure chamber 11 (see reference 1) via the connecting passage 63. Figure 6 (Connection). Hereinafter, the gap between the outer peripheral surface 61d of cylinder 6 and pump body 1 will be referred to as the "fixed gap".

[0103] A press-in portion 64 is formed on the outer peripheral surface 61d of the large-diameter portion 61. The press-in portion 64 is provided on the axial end face 61b side of the large-diameter portion 61. The diameter of the press-in portion 64 is set to be larger than the diameter of the outer peripheral surface 61d portion. The press-in portion 64 is pressed into the third chamber 1c of the pump body 1 (see reference). Figure 2 The length of the axially pressed portion 64 of the large-diameter portion 61 will be described later.

[0104] [The operation of fixing the cylinder to the pump body]

[0105] Next, the process of fixing cylinder 6 to pump body 1 will be explained.

[0106] First, the large-diameter portion 61 of cylinder 6 is inserted into the third chamber 1c of pump body 1, and the pressing portion 64 is pressed into the inner circumferential surface of the third chamber 1c. At this time, the end face 61a of cylinder 6 is pushed to the bottom surface of the third chamber 1c. As a result, the end face 61a contacts the step portion (flat portion) between the first chamber 1a and the third chamber 1c.

[0107] Next, from below ( Figure 2 A load of several hundred kN is applied to the fixing part 1x of the pump body 1 (below). As a result, the fixing part 1x undergoes plastic deformation, and the cylinder 6 is fixed to the pump body 1. Furthermore, after the fixing part 1x undergoes plastic deformation, the load of several hundred kN is released, but a residual load is also generated after the load is released, which pushes the end face 61a of the cylinder 6 toward the bottom surface of the third chamber 1c.

[0108] [Pressure inside and around the cylinder]

[0109] Next, the pressure inside and around cylinder 6 will be explained.

[0110] Hereinafter, the pressing portion between the end face 61a of cylinder 6 and the bottom surface of the third chamber 1c will be referred to as the "face pressing portion". To ensure stable sealing at the face pressing portion, it is necessary to control not only the surface roughness and characteristics (properties and state) of the end face 61a and the bottom surface of the third chamber 1c, but also the value of the residual load. Therefore, achieving stable sealing at the face pressing portion is quite difficult. While it may be possible to prevent fuel ingress (through) at the face pressing portion of one individual, it may not be possible to prevent fuel ingress (through) at the face pressing portion of another individual.

[0111] During the pressurization process, pressurization chamber 11 (refer to...) Figure 2The pressure becomes high. At this time, the pressure of the tiny gap generated between the plunger 2 and the cylinder 6 is the same as the pressure in the pressure chamber 11 at the end of the pressure chamber 11 side, and gradually decreases as it moves towards the opposite side of the pressure chamber 11 side. The pressure at the end of the tiny gap generated between the plunger 2 and the cylinder 6 on the opposite side of the pressure chamber 11 side becomes the same as the pressure in the low-pressure auxiliary chamber 17a. Hereinafter, the tiny gap generated between the plunger 2 and the cylinder 6 will be referred to as the "sliding gap".

[0112] When the pressure-sealing section can completely seal the fuel, the fuel in the pressurized chamber 11 does not reach the fixed gap (the gap created between cylinder 6 and pump body 1). As a result, the pressure in the sliding gap is higher than the pressure in the fixed gap. Consequently, the inner circumferential surface 61c of cylinder 6 is pushed by the fuel, and the sliding gap widens. When the sliding gap widens, the amount of fuel leaking from it increases. The result is a problem of insufficient high-pressure fuel output or low volumetric efficiency, failing to deliver the required amount of fuel at high pressure to the internal combustion engine (engine).

[0113] If the pressure chamber cannot completely seal the fuel, the fuel in the pressurized chamber 11 reaches the fixed gap. Therefore, the pressure in the sliding gap is lower than the pressure in the fixed gap. Consequently, the outer circumferential surface 61d of the cylinder 6 is pushed by the fuel, causing the sliding gap to decrease or become zero. When the sliding gap decreases or becomes zero, a second problem arises: the plunger 2 adheres to the cylinder 6. Even when the sliding gap is reduced to solve the first problem, the adhesion between the plunger 2 and the cylinder 6 becomes even more pronounced.

[0114] Therefore, as Figure 2 and Figure 6 As shown, in this embodiment, a connecting passage 63 is provided on the end face 61a of the cylinder 6, so that the fuel in the pressurization chamber 11 always reaches the fixed gap. Therefore, the pressure in the fixed gap becomes the same as the pressure in the pressurization chamber 11. The pressure in the sliding gap becomes lower than the pressure in the fixed gap.

[0115] Fuel that has entered the fixed gap is sealed at the injection section 64 and the fixed section 1x. Therefore, the pressure in the fixed gap is not released to the same low pressure as in the auxiliary chamber 17a. Thus, by appropriately setting the position of the injection section 64, where fuel is not injected, the pressure difference between the fixed gap and the sliding gap between the plunger 2 and the cylinder 6 can be adjusted to a predetermined range. As a result, deformation of the cylinder 6 caused by the pressure difference between the two can be suppressed.

[0116] When the end of the pressurized chamber 11 side in the pressurized section 64 is too close to the pressurized chamber 11, the area where fuel does not penetrate between the outer peripheral surface 61d of the cylinder 6 and the pump body 1 increases. As a result, the area with high pressure in the sliding clearance is opposite to the area with zero pressure in the fixed clearance. Consequently, the inner peripheral surface 61c of the cylinder 6 is pushed by fuel, and the sliding clearance widens.

[0117] In this embodiment, the end of the pressurized chamber 11 side in the pressing part 64 is positioned opposite to a region where the pressure of the sliding gap is 1 / 2 to 1 / 3 of the pressure of the pressurized chamber 11. This reduces the pressure difference between the fixed gap and the sliding gap.

[0118] As a result, the pressure in the pressurization chamber 11 and the pressure in the fixed gap become high pressure during the pressurization stroke, while the pressure in the sliding gap is equal to or slightly lower. This prevents deformation of the inner circumferential surface 61c of the cylinder 6. Alternatively, it suppresses deformation of the inner circumferential surface 61c of the cylinder 6 to a level that prevents adhesion. Consequently, the amount of fuel flowing from the pressurization chamber 11 to the auxiliary chamber 17a through the sliding gap is reduced, allowing the required amount of fuel to be discharged at high pressure.

[0119] On the other hand, during the return stroke and the intake stroke, the pressure in the pressurization chamber 11 and the pressure in the fixed clearance become low pressure. The pressure in the sliding clearance also becomes low pressure. Therefore, the sliding clearance becomes the initially set value, and the piston 2 does not stick to the cylinder 6. Through the above, the first and second problems mentioned above can be solved simultaneously.

[0120] Furthermore, the allowable range of the pressure difference between the fixed clearance and the sliding clearance can be set taking into account the deformation of cylinder 6 caused by the pressure difference. In addition, the position of the end of the pressurized chamber 11 side in the pressurization section 64 can be appropriately determined according to the pressure of the pressurized chamber 11 and the allowable range of the pressure difference.

[0121] The pressure in the sliding gap is approximately proportional to the distance from the pressurization chamber 11. That is, the pressure in the sliding gap decreases approximately proportionally the farther away from the pressurization chamber 11. Therefore, the position of the end of the pressurization chamber 11 side in the pressing part 64 can be set based on the sliding range of the plunger 2.

[0122] In this embodiment, the end of the pressurized chamber 11 side in the pressurized section 64 is positioned at a length that reaches 1 / 3 to 1 / 2 of the sliding range of the plunger 2. Furthermore, the length of 1 / 3 to 1 / 2 of the sliding range of the plunger 2 is the length (distance) from the bottom dead center of the plunger 2. That is, the end of the pressurized chamber 11 side in the pressurized section 64 is positioned relative to the area between the point where the plunger 2 rises to 1 / 3 from the bottom dead center and the point where it rises to 1 / 2. In this case, the pressure difference between the fixed gap and the sliding gap can also be reduced.

[0123] 2. Second Implementation Method

[0124] Next, the high-pressure fuel supply pump of the second embodiment of the present invention is described using... Figure 8 Please provide an explanation.

[0125] Figure 8 This is a perspective view of the cylinder of the high-pressure fuel supply pump according to the second embodiment.

[0126] The high-pressure fuel supply pump of the second embodiment has the same structure as the high-pressure fuel supply pump 100 of the first embodiment. The only difference between the high-pressure fuel supply pump of the second embodiment and the high-pressure fuel supply pump 100 of the first embodiment is the cylinder. Therefore, the cylinder 6A of the second embodiment will be described here, and the description of the structure common to the high-pressure fuel supply pump 100 will be omitted.

[0127] [The shape of the tank]

[0128] like Figure 8 As shown, cylinder 6A is formed into a cylindrical shape with a guide hole 6a extending in the axial direction. Cylinder 6A has a large-diameter portion 61 that is continuous in the axial direction and a small-diameter portion 62 that is smaller in diameter than the large-diameter portion 61. The large-diameter portion 61 forms the upper part of cylinder 6, and the small-diameter portion 62 forms the lower part of cylinder 6.

[0129] The large-diameter portion 61 has an end face 61a as one end (upper end) and an end face 61b as the other end (lower end) as the axial direction. The large-diameter portion 61 is inserted into the pump body 1 (see reference). Figure 2 The small diameter portion 62 is continuous with the end face 61b of the large diameter portion 61. The small diameter portion 62 is disposed on the outside of the pump body 1.

[0130] The end face 61a of the large-diameter portion 61 is formed in an annular shape. The end face 61a is aligned with the pump body 1 (see reference). Figure 2 The bottom surface of the third chamber 1c in the ) abuts against it. A connecting passage 63 is provided on the end face 61a. The connecting passage 63 is formed as a groove extending radially in the large diameter portion 61.

[0131] A press-in portion 64 and a press-in portion 65 are formed on the outer peripheral surface 61d of the large-diameter portion 61. The press-in portion 64 is provided on the axial end face 61b side of the large-diameter portion 61. The press-in portion 65 is provided on the axial end face 61a side of the large-diameter portion 61. That is, the press-in portions 64 and 65 are arranged on both sides of the outer peripheral surface 61d in the axial direction of the large-diameter portion 61. Therefore, the "fixed gap" in the second embodiment becomes the press-in portion 64, the press-in portion 65, and the pump body 1 (see reference 1). Figure 2 The space (gap) created between them.

[0132] The diameters of the pressing portions 64 and 65 are set to be larger than the diameter of the outer peripheral surface 61d. The pressing portions 64 and 65 are pressed into the third chamber 1c of the pump body 1 (see reference). Figure 2 The length of the axially pressed portion 64 of the large-diameter portion 61 is the same as that of the cylinder 6 in the first embodiment.

[0133] A pressing section connecting passage 65a is provided in the pressing section 65. The pressing section connecting passage 65a extends axially in the large diameter section 61. One end of the pressing section connecting passage 65a reaches the end face 61a, and the other end reaches the outer peripheral surface 61d. Moreover, the connecting passage 63 is set to extend from the inner peripheral surface 61c of the large diameter section 61 to the pressing section 65. When the cylinder 6A is fixed to the pump body 1, the fixing gap is connected via the pressing section connecting passage 65a and the connecting passage 63.

[0134] When using such a cylinder 6A, the same effects as when using the cylinder 6 of the first embodiment can be achieved. That is, the pressure in the pressurization chamber 11 and the pressure in the fixed gap during the pressurization stroke become high pressure, and the pressure in the sliding gap is equal to or slightly lower than that. As a result, deformation of the inner circumferential surface 61c side of the cylinder 6 can be prevented. Alternatively, deformation of the inner circumferential surface 61c side of the cylinder 6A can be suppressed to the point that adhesion does not occur. As a result, the amount of fuel flowing from the pressurization chamber 11 to the auxiliary chamber 17a through the sliding gap can be reduced, and the necessary amount of fuel can be discharged at high pressure.

[0135] Furthermore, during the return and intake strokes, the pressure in the pressurization chamber 11 and the pressure in the fixed gap become low. The pressure in the sliding gap also becomes low. Therefore, the sliding gap reaches its initially set value, preventing the plunger 2 from sticking to the cylinder 6A. Through the above, both the first and second problems mentioned above can be solved simultaneously. Moreover, since there are two points where the cylinder 6A is pressed in and fixed, it can be more securely fixed to the pump body 1. As a result, in driving the high-pressure fuel pump of the second embodiment, the risk of the cylinder 6A loosening its fixation to the pump body 1 can be reduced.

[0136] 3. Summary

[0137] As described above, the high-pressure fuel supply pump 100 (fuel pump) of the first embodiment includes: a plunger 2 (plunger) that reciprocates; a cylinder 6 (cylinder) whose guide hole 6a (guide hole) for guiding the reciprocating motion of the plunger 2 extends axially; and a pump body 1 (pump body) having a third chamber 1c (cylinder insertion hole) into which the cylinder 6 is pressed, and a pressurization chamber 11 (pressurization chamber) communicating with the third chamber 1c whose volume increases or decreases due to the reciprocating motion of the plunger 2. The pressure of the fixed gap generated between the cylinder 6 and the pump body 1 is set to be equal to or greater than the pressure of the sliding gap generated between the plunger 2 and the cylinder 6.

[0138] Therefore, during the pressurization stroke, the pressure in the pressurization chamber 11 and the pressure in the fixed gap become high pressure, while the pressure in the sliding gap is equal to or slightly lower. Thus, deformation on the guide hole 6a side of cylinder 6 can be suppressed to a level that prevents adhesion. As a result, the amount of fuel flowing from the pressurization chamber 11 to the auxiliary chamber 17a through the sliding gap is reduced, allowing the required amount of fuel to be discharged at high pressure. Furthermore, during the return stroke and the intake stroke, the pressure in the pressurization chamber 11, the pressure in the fixed gap, and the pressure in the sliding gap also become low pressure. As a result, the sliding gap reaches its initially set value, preventing adhesion between the plunger 2 and cylinder 6.

[0139] Furthermore, the high-pressure fuel supply pump 100 (fuel pump) of the first embodiment described above has a connecting passage 63 (connecting passage) that connects the fixed gap to the pressurization chamber 11 (pressurization chamber). This allows the pressure in the fixed gap to be easily made the same as the pressure in the pressurization chamber 11. As a result, the pressure in the fixed gap can be easily set to be equal to or greater than the pressure in the sliding gap.

[0140] Furthermore, the cylinder 6 in the high-pressure fuel supply pump 100 (fuel pump) of the first embodiment described above has an end face 61a that contacts the bottom surface of the third chamber 1c (cylinder insertion hole) in the pump body 1 (pump body). A connecting passage 63 is formed by providing a groove on the end face 61a of the cylinder 6. This allows for easy formation of the connecting passage 63. Additionally, the connecting passage of the present invention can also be formed by providing a protrusion on the end face 61a of the cylinder 6.

[0141] Alternatively, the connecting passage of the present invention can also be formed by providing a groove or protrusion on the bottom surface of the third chamber 1c (cylinder insertion hole). In this case, the connecting passage of the present invention can also be easily formed.

[0142] Furthermore, the cylinder 6 of the high-pressure fuel supply pump 100 (fuel pump) of the first embodiment described above has a pressing section 64, which is pressed into the end opposite to the pressurized chamber 11 side of the third chamber 1c (cylinder insertion hole). The position of the end of the pressing section 64 on the pressurized chamber 11 side is set based on the pressure of the pressurized chamber 11 during the pressurization stroke. Therefore, within the fixed gap, a region with the same pressure as the pressurized chamber 11 can be appropriately set. The difference between the pressure in the fixed gap and the pressure in the sliding gap can be limited to a predetermined range.

[0143] Furthermore, the cylinder 6 of the high-pressure fuel supply pump 100 (fuel pump) of the first embodiment described above has a pressing section 64, which is pressed into the end opposite to the pressurization chamber 11 side of the third chamber 1c (cylinder insertion hole). The end of the pressing section 64 on the pressurization chamber 11 side is opposite to the region where the pressure of the sliding gap during the pressurization stroke is 1 / 2 to 1 / 3 of the pressure of the pressurization chamber 11. As a result, the pressure difference between the fixed gap and the sliding gap can be reduced.

[0144] Furthermore, the cylinder 6 of the high-pressure fuel supply pump 100 (fuel pump) of the first embodiment described above has a pressing section 64, which is pressed into the end opposite to the pressurized chamber 11 (pressurized chamber) side of the third chamber 1c (cylinder insertion hole). The end of the pressing section 64 on the pressurized chamber 11 side is positioned at a length of 1 / 3 to 1 / 2 of the sliding range of the plunger 2 from its bottom dead center. This reduces the pressure difference between the fixed clearance and the sliding clearance.

[0145] Furthermore, the cylinder 6A of the high-pressure fuel supply pump (fuel pump) in the second embodiment described above has: a pressing part 64 (first pressing part), which is pressed into the end opposite to the pressurized chamber 11 (pressurized chamber) side of the third chamber 1c (cylinder insertion hole); and a pressing part 65 (second pressing part), which is pressed into the end of the third chamber 1c on the pressurized chamber 11 side. The fixed gap is the space between the pressing part 64, the pressing part 65 and the pump body 1 (pump body), and has a connecting passage 63 that connects the fixed gap to the pressurized chamber 11 and a pressing part connecting passage 65a (connecting passage). As a result, the pressure in the fixed gap can be easily made the same as the pressure in the pressurized chamber 11. Moreover, since there are two pressing and fixing points, the cylinder 6A can be more firmly fixed relative to the pump body 1.

[0146] Furthermore, the cylinder 6A of the high-pressure fuel supply pump (fuel pump) in the second embodiment described above has an end face 61a that contacts the bottom surface of the third chamber 1c (cylinder insertion hole) in the pump body 1 (pump body). The connecting passage 63 and the pressing portion connecting passage 65a (connecting passage) are formed by providing grooves in the end face 61a and the pressing portion 65 (second pressing portion) of the cylinder 6. This allows for easy formation of the connecting passage 63 and the pressing portion connecting passage 65a. Additionally, the connecting passage of the present invention can also be formed by providing protrusions in the end face 61a and the pressing portion 65 of the cylinder 6A. Furthermore, the connecting passage of the present invention can also be formed by providing grooves or protrusions in the bottom surface and inner circumferential surface of the third chamber 1c (cylinder insertion hole).

[0147] 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 embodiments and can be implemented in various modifications without departing from the spirit of the invention. Furthermore, the above embodiments are detailed for ease of understanding of the present invention and are not limited to having all the described structures.

[0148] For example, in the above embodiment, one connecting path 63 or one push-in connecting path 65a is provided. However, multiple connecting paths may also be provided in the present invention.

[0149] Explanation of reference numerals in the attached figures

[0150] 1…Pump body; 1a…First chamber; 1b…Second chamber (pressure reducing valve chamber); 1c…Third chamber; 1d…Suction passage (connecting hole); 1e…Connecting hole; 1g…Supply connecting hole; 1x…Fixing part; 2…Plunger; 3…Electromagnetic suction valve mechanism; 4…Pressure reducing valve mechanism; 5…Suction connector; 6, 6A…Cylinder; 6a…Guide hole; 8…Discharge valve mechanism; 9…Pressure pulsation reduction mechanism; 10…Low-pressure fuel chamber; 11…Pressure chamber; 12…Discharge connector; 12a…Discharge passage; 12b…Fuel… Material discharge outlet; 12c…welding section; 30…suction valve chamber; 61…large diameter section; 61a…end face; 61b…end face; 61c…inner circumferential surface; 61d…outer circumferential surface; 62…small diameter section; 63…connecting passage; 64, 65…pressing section; 65a…pressing section connecting passage; 80…discharge valve chamber; 100…high pressure fuel supply 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, have: A plunger that reciprocates; A cylinder, wherein a guide hole for guiding the reciprocating motion of the plunger extends axially; and The pump body has a cylinder insertion hole into which the cylinder is pressed, and a pressurization chamber that communicates with the cylinder insertion hole and whose volume increases or decreases due to the reciprocating motion of the plunger. The pressure of the fixed gap between the cylinder and the pump body is set to be equal to or greater than the pressure of the sliding gap between the plunger and the cylinder. It has a connecting passage that connects the fixed gap to the pressurization chamber. The cylinder has an end face that contacts the bottom surface of the cylinder insertion hole in the pump body. The connecting passage is formed by providing a groove or protrusion on the end face of the cylinder, or The connecting passage is formed by providing a groove or protrusion on the bottom surface of the cylinder insertion hole. The cylinder has a press-in portion that is pressed into the end of the cylinder insertion hole on the side opposite to the pressurization chamber side. The end of the pressurized chamber side of the pressing section is opposite to the region where the pressure of the sliding gap during the pressurization stroke is 1 / 2 to 1 / 3 of the pressure of the pressurized chamber, or The end of the pressurized chamber side of the pressurized part is positioned at a length of 1 / 3 to 1 / 2 of the sliding range of the plunger from the bottom dead center of the plunger.

2. The fuel pump as claimed in claim 1, characterized in that: The cylinder has: a first pressing portion, which is pressed into the end of the cylinder insertion hole on the side opposite to the pressurization chamber side; and a second pressing portion, which is pressed into the end of the cylinder insertion hole on the pressurization chamber side. The fixed gap is the space between the first pressing part, the second pressing part, and the pump body. It has a connecting passage that connects the fixed gap to the pressurization chamber.

3. The fuel pump as described in claim 2, characterized in that: The cylinder has an end face that contacts the bottom surface of the cylinder insertion hole in the pump body. The connecting passage is formed by providing grooves or protrusions on the end face of the cylinder and the second press-in portion.

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