Fuel pump

Abstract

A fuel pump includes a plunger that performs reciprocation, a retainer that has a mounting portion mounted to a lower end portion of the plunger, and a spring that exerts a force on the plunger via the retainer. The mounting portion has an engaging portion that engages with a necked portion formed in the lower end portion of the plunger. A circle formed by a corner portion of the engaging portion and an inner peripheral wall of the spring has a diameter that is smaller than a diameter of the lower end portion of the plunger.

Description

TECHNICAL FIELD

[0001] The present application relates to a fuel pump for an internal combustion engine of an automobile. BACKGROUND

[0002] In a direct injection type engine in which fuel is directly injected into a combustion chamber of an engine (an internal combustion engine) of an automobile or the like, a high-pressure fuel pump for making fuel into high pressure is widely used. As a related art of this high-pressure fuel pump, for example, described in Patent Literature 1.

[0003] The high-pressure fuel pump described in Patent Literature 1 has a plunger which moves up and down by a rotational movement of a cam installed on a camshaft of an engine. A retainer is installed at a lower end portion of the plunger. And, the plunger is urged to the cam side by a spring via the retainer.

[0004] PRIOR ART DOCUMENT

[0005] PATENT LITERATURE

[0006] Patent Literature 1: International Publication No. 2004 / 63559 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the conventional high-pressure fuel pump, before the retainer is housed in the tappet, when the high-pressure fuel pump is installed in a fuel pump mounting portion provided in the internal combustion engine, the plunger and the spring are eccentric, and the retainer can be detached from the plunger.

[0009] In view of the above problem, an object of the present application is to provide a fuel pump in which detachment of a retainer from a plunger can be prevented.

[0010] MEANS OF SOLVING THE PROBLEM

[0011] In order to solve the above problem and achieve the object, the fuel pump of the present application has a plunger which performs a reciprocating movement, a retainer which has a mounting portion installed at a lower end portion of the plunger, and a spring which urges the plunger via the retainer. The mounting portion of the retainer has an engaging portion which engages with a necked portion formed at the lower end portion of the plunger. A diameter of a circle formed by a corner portion of the engaging portion and an inner peripheral wall of the spring is smaller than a diameter of the lower end portion of the plunger.

[0012] EFFECT OF THE INVENTION

[0013] According to the fuel pump configured as described above, detachment of the retainer from the plunger can be prevented.

[0014] Further, the above-mentioned objects, configurations, and effects other than the above are clarified by the following embodiments. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0017] Figure 3 is a horizontal sectional view from above of a high-pressure fuel pump according to an embodiment of the present application.

[0018] Figure 4 is a longitudinal sectional view of a high-pressure fuel pump according to an embodiment of the present application (two).

[0019] Figure 5 is a sectional view showing the lower end portion of a retainer and a plunger in a high-pressure fuel pump according to an embodiment of the present application.

[0020] Figure 6 is a perspective view showing a retainer of a high-pressure fuel pump according to an embodiment of the present application.

[0021] Figure 7 is a plan view showing a retainer of a high-pressure fuel pump according to an embodiment of the present application.

[0022] Figure 8 is a front view of a retainer of a high-pressure fuel pump according to an embodiment of the present application, as viewed from an insertion portion.

[0023] Figure 9 is a front view showing a state in which a retainer of a high-pressure fuel pump according to an embodiment of the present application is mounted on a plunger.

[0024] Figure 10 is an explanatory view showing a state in which a retainer of a high-pressure fuel pump according to an embodiment of the present application is mounted on a plunger.

[0025] Figure 11 is a sectional view showing the clearance relationship among a retainer, a plunger, and a spring in a high-pressure fuel pump according to an embodiment of the present application.

[0026] Figure 12A and 12B is a view showing a state in which a retainer is eccentric in a high-pressure fuel pump according to an embodiment of the present application, Figure 12A is a plan view, Figure 12B is a sectional view.

[0027] Figure 13 is a longitudinal sectional view showing another example of a high-pressure fuel pump according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] 1. An embodiment of a high-pressure fuel pump

[0029] Next, a high-pressure fuel pump according to an embodiment of the present application will be described. In addition, the same reference numerals are given to common components in each drawing.

[0030] [Fuel supply system]

[0031] First, a fuel supply system using the high-pressure fuel pump according to the present embodiment will be described. Figure 1

[0032] Figure 1 is a whole configuration view of a fuel supply system using the high-pressure fuel pump according to the present embodiment.

[0033] As shown in Figure 1 , the fuel supply system includes a high-pressure fuel pump 100, an ECU (Engine Control Unit) 27, a fuel tank 20, a common rail 23, and a plurality of injectors 24. Components of the high-pressure fuel pump 100 are integrated in a pump body 1.

[0034] Fuel in the fuel tank 20 is drawn by a feed pump 21 driven based on a signal from the ECU 27. The drawn fuel is pressurized to an appropriate pressure by a pressure regulator not shown, and is delivered to a low-pressure fuel inlet 10a provided on a suction joint 51 of the high-pressure fuel pump 100 through a fuel pipe 28 (refer to Figure 2 ).

[0035] The high-pressure fuel pump 100 pressurizes fuel supplied from the fuel tank 20, and delivers it to the common rail 23. The plurality of injectors 24 and a fuel pressure sensor 26 are installed in the common rail 23. The plurality of injectors 24 are installed according to the number of cylinders (combustion chambers), and inject fuel according to a drive current output from the ECU 27. The fuel supply system according to the present embodiment is a so-called direct injection engine system in which the injectors 24 directly inject fuel into the cylinder bores of the engine.

[0036] The fuel pressure sensor 26 outputs detected pressure data to the ECU 27. The ECU 27 calculates an appropriate injection fuel amount (target injection fuel length) or an appropriate fuel pressure (target fuel pressure), and the like, based on engine state quantities (for example, crank angle, throttle opening degree, engine speed, fuel pressure, and the like) obtained from various sensors.

[0037] The ECU 27 controls the drive of the high-pressure fuel pump 100 and the plurality of injectors 24 based on the calculation results of the fuel pressure (target fuel pressure), and the like. That is, the ECU 27 has a pump control portion that controls the high-pressure fuel pump 100 and an injector control portion that controls the injectors 24.

[0038] ​The high-pressure fuel pump 100 includes a plunger 2, a pressure pulsation reduction mechanism 9, an electromagnetic intake valve mechanism 300 as a capacity variable mechanism, an overflow valve mechanism 200, and a discharge valve mechanism 8. Fuel flowing in from the low-pressure fuel intake port 10a passes through the pressure pulsation reduction mechanism 9 and the low-pressure fuel intake passage 10d to reach the intake port 31b of the electromagnetic intake valve mechanism 300.

[0039] Fuel flowing into the electromagnetic intake valve mechanism 300 passes through the intake valve 30, flows through the intake passage 1a formed on the pump body 1, and then flows into the pressurization chamber 11. The pump body 1 slidably holds the plunger 2. The plunger 2 is supported by the engine cam 93 (see reference). Figure 2 It 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.

[0040] In the pressurization chamber 11, fuel is drawn in from the electromagnetic intake valve mechanism 300 during the downward stroke of the plunger 2, and the fuel is 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, and high-pressure fuel is pumped to the common rail 23 through the fuel discharge port of the discharge connector 12. The discharge of fuel from the high-pressure fuel pump 100 is operated by opening and closing the electromagnetic intake valve mechanism 300. Moreover, the opening and closing of the electromagnetic intake valve mechanism 300 is controlled by the ECU 27.

[0041] In the event of abnormally high pressure in the common rail 23 due to a malfunction of injector 24, etc., when the fuel outlet of the discharge connector 12 connected to the common rail 23 (refer to...) Figure 2 When the differential pressure between the pressure chamber 11 and the pressure chamber 200 exceeds the opening pressure (specified value) of the relief valve mechanism 200, the relief valve mechanism 200 opens. As a result, the abnormally high-pressure fuel returns to the pressure chamber 11 through the relief valve mechanism 200. Consequently, the common rail 23 and other piping are protected.

[0042] [High-pressure fuel pump]

[0043] Next, we will refer to Figures 2 to 4 Explain the composition of the high-pressure fuel pump 100.

[0044] Figure 2 This is a longitudinal section view (one) observed in a section orthogonal to the horizontal direction of the high-pressure fuel pump 100. Figure 3 This is a horizontal cross-sectional view observed in a section orthogonal to the vertical direction of the high-pressure fuel pump 100. Figure 4 This is a longitudinal section view (Part Two) observed in a section orthogonal to the horizontal direction of the high-pressure fuel pump 100.

[0045] like Figure 2 and Figure 3As shown, the suction passage 1a and the mounting flange 1e (see FIG. 2) are provided on the pump body 1 of the high-pressure fuel pump 100. Figure 3 The mounting flange 1e is in close contact with a fuel pump mounting portion 90 of an engine (internal combustion engine), and is fixed by a plurality of bolts (screws) not shown. That is, the high-pressure fuel pump 100 is fixed to the fuel pump mounting portion 90 by the mounting flange 1e.

[0046] As shown, an O-ring 61 is interposed between the fuel pump mounting portion 90 and the pump body 1. The O-ring 61 prevents engine oil from leaking to the outside of the engine (internal combustion engine) through the fuel pump mounting portion 90 and the pump body 1. Figure 2

[0047] Further, a cylinder 6 that guides the reciprocating motion of the plunger 2 is mounted on the pump body 1 of the high-pressure fuel pump 100. The cylinder 6 is formed in a cylindrical shape, and is press-fitted to the pump body 1 at the outer peripheral side thereof. The pump body 1 and the cylinder 6 form, together with the electromagnetic suction valve mechanism 300, the plunger 2, and the discharge valve mechanism 8 (see FIG. 2), a pressurizing chamber 11. Figure 3

[0048] A fixing portion 1c that engages with the central portion in the axial direction of the cylinder 6 is provided on the pump body 1. The fixing portion 1c is plastically deformable. Further, the fixing portion 1c urges the cylinder 6 upward (in the upward direction in FIG. 1). The upper end surface (one end surface) of the cylinder 6 is in abutment with the pump body 1. As a result, fuel pressurized in the pressurizing chamber 11 does not leak from between the upper end surface of the cylinder 6 and the pump body 1. Figure 2

[0049] A tappet 92 is provided at the lower end of the plunger 2. The tappet 92 converts the rotational motion of a cam 93 mounted on a camshaft of the engine into up-and-down motion, and transmits the up-and-down motion to the plunger 2. The plunger 2 is urged by the spring 4 via a retainer 15 toward the cam 93, and is press-fitted to the tappet 92. The plunger 2 reciprocates together with the tappet 92, and changes the volume of the pressurizing chamber 11. Further, the detailed configuration of the retainer 15 will be described later.

[0050] Further, a seal holder 7 is disposed between the cylinder 6 and the retainer 15. The seal holder 7 is formed in a cylindrical shape into which the plunger 2 is inserted. A sub-chamber 7a is formed at the upper end portion of the seal holder 7 on the side of the cylinder 6. On the other hand, the lower end portion of the seal holder 7 on the side of the retainer 15 holds a plunger seal 13.

[0051] The plunger seal 13 is in slidable contact with the outer periphery of the plunger 2. When the plunger 2 reciprocates, the plunger seal 13 seals the fuel of the sub-chamber 7a, and prevents the fuel of the sub-chamber 7a from flowing into the inside of the engine. Further, the plunger seal 13 prevents lubricating oil (also including engine oil) that lubricates sliding portions in the engine from flowing into the inside of the pump body 1.

[0052] In​​​Figure 2 The plunger 2 reciprocates in the up-and-down direction. When the plunger 2 descends, the volume of the pressurizing chamber 11 expands, and when the plunger 2 ascends, the volume of the pressurizing chamber 11 decreases. That is, the plunger 2 is disposed so as to reciprocate in a direction in which the volume of the pressurizing chamber 11 expands and decreases.

[0053] The plunger 2 has a large-diameter portion 2a and a small-diameter portion 2b. When the plunger 2 reciprocates, the large-diameter portion 2a and the small-diameter portion 2b are located in the sub-chamber 7a. Therefore, the volume of the sub-chamber 7a increases and decreases by the reciprocation of the plunger 2.

[0054] The sub-chamber 7a communicates with the low-pressure fuel chamber 10 through the fuel passage 10e (refer to Figure 3 and Figure 4 ). When the plunger 2 descends, fuel flow from the sub-chamber 7a to the low-pressure fuel chamber 10 occurs, and when the plunger 2 ascends, fuel flow from the low-pressure fuel chamber 10 to the sub-chamber 7a occurs. Thus, it is possible to reduce the fuel flow to and from the inside and outside of the pump during the suction stroke or the return stroke of the high-pressure fuel pump 100, and it is possible to reduce the pressure pulsation generated inside the high-pressure fuel pump 100.

[0055] In addition, the pump body 1 is provided with an overflow valve mechanism 200 that communicates with the pressurizing chamber 11. The overflow valve mechanism 200 has a valve seat member 201, an overflow valve 202, an overflow valve holder 203, an overflow valve spring 204, and a spring support member 205.

[0056] The valve seat member 201 houses the overflow valve spring 204 and forms an overflow valve chamber. One end of the overflow valve spring 204 abuts against the spring support member 205, and the other end abuts against the overflow valve holder 203. The overflow valve holder 203 engages with the overflow valve 202. The force of the overflow valve spring 204 acts on the overflow valve 202 via the overflow valve holder 203.

[0057] The overflow valve 202 is urged by the force of the overflow valve spring 204 and blocks the fuel passage of the valve seat member 201. The fuel passage of the valve seat member 201 communicates with the discharge passage 12b (refer to Figure 3 ). The movement of fuel between the pressurizing chamber 11 (upstream side) and the valve seat member 201 (downstream side) is blocked by the contact (abutment) of the overflow valve 202 and the valve seat member 201.

[0058] When the pressure in the common rail 23 or the member in front of the common rail 23 becomes high, the fuel on the valve seat member 201 side urges the overflow valve 202, and the overflow valve 202 moves against the force of the overflow valve spring 204. As a result, the overflow valve 202 opens, and the fuel in the discharge passage 12b returns to the pressurizing chamber 11 through the fuel passage 200a of the valve seat member 201. Therefore, the pressure at which the overflow valve 202 opens is determined by the force of the overflow valve spring 204.

[0059] In addition, the overflow valve mechanism 200 of this embodiment is connected to the pressurization chamber 11, but it is not limited to this. For example, it can also be connected to the low-pressure passage.

[0060] like Figure 3 and Figure 4 As shown, a suction connector 51 is installed on the side of the pump body 1. The suction connector 51 connects to the fuel pipe 28 (see reference 20) through which fuel supplied from the fuel tank 20 passes. Figure 1 Fuel is supplied from the fuel tank 20 to the interior of the high-pressure fuel pump 100 via the intake joint 51.

[0061] The intake connector 51 has an intake flow path 52 communicating with a low-pressure fuel intake port 10a connected to the fuel line 28. Fuel passing through the intake flow path 52 of the intake connector 51 is then conveyed via a pressure pulsation reduction mechanism 9 provided in the low-pressure fuel chamber 10 and a low-pressure fuel intake passage 10d (see reference). Figure 2 The suction port 31b of the electromagnetic suction valve mechanism 300 (see reference) Figure 2 A suction filter is installed in the fuel passage that communicates with the suction flow path 52 of the suction connector 51. The suction filter removes foreign objects present in the fuel and prevents foreign objects from entering the high-pressure fuel pump 100.

[0062] like Figure 2 and Figure 4 As shown, a low-pressure fuel chamber (buffer chamber) 10 is provided on the pump body 1 of the high-pressure fuel pump 100. The low-pressure fuel chamber 10 is covered by a buffer cover 14. The buffer cover 14 is, for example, formed as a cylindrical (cup-shaped) tube closed on one side.

[0063] like Figure 2 As shown, the low-pressure fuel chamber 10 is divided into an upper buffer 10b and a lower buffer 10c by the pressure pulsation reduction mechanism 9. When fuel flowing into the pressurization chamber 11 returns to the low-pressure fuel intake passage 10d through the electromagnetic intake valve mechanism 300 in the open state (see reference). Figure 2 When the pressure pulsation occurs, pressure pulsation is generated 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 pump 100 on the fuel piping 28.

[0064] Next, the electromagnetic suction valve mechanism 300 will be described.

[0065] The electromagnetic suction valve mechanism 300 is inserted into a transverse hole formed on the pump body 1. The electromagnetic suction valve mechanism 300 includes: a suction valve seat 31 pressed into the transverse hole formed on the pump body 1, a suction valve 30, a suction valve force spring 33, a valve stem 35, a movable iron core 36, a valve stem force spring 40, and an electromagnetic coil (solenoid) 43.

[0066] The suction valve seat 31 is formed in a cylindrical shape, and has a seating portion provided on an inner peripheral portion. Further, a suction port 31b is formed in the suction valve seat 31 so as to reach from an outer peripheral portion to the inner peripheral portion. The suction port 31b communicates with the low-pressure fuel suction passage 10d in the low-pressure fuel chamber 10.

[0067] In a horizontal hole formed in the pump body 1, a stopper 32 is provided so as to oppose the seating portion of the suction valve seat 31. Further, the suction valve 30 is provided between the stopper 32 and the seating portion. Further, a suction valve urging spring 33 is interposed between the stopper 32 and the suction valve 30. The suction valve urging spring 33 urges the suction valve 30 toward the seating portion side.

[0068] The suction valve 30 closes the communication between the suction port 31b and the pressurizing chamber 11 by abutting against the seating portion. Thus, the electromagnetic suction valve mechanism 300 becomes a closed valve state. On the other hand, the suction valve 30 opens the communication between the suction port 31b and the pressurizing chamber 11 by abutting against the stopper 32. Thus, the electromagnetic suction valve mechanism 300 becomes an open valve state.

[0069] A valve rod 35 penetrates the suction valve seat 31. One end of the valve rod 35 abuts against the suction valve 30. A valve rod urging spring 40 urges the suction valve 30 toward an open valve direction, which is the stopper 32 side, via the valve rod 35. One end of the valve rod urging spring 40 is engaged with a flange portion provided on an outer peripheral portion of the valve rod 35. The other end of the valve rod urging spring 40 is engaged with a magnetic core 39 provided so as to surround the valve rod urging spring 40.

[0070] A movable iron core 36 opposes an end surface of the magnetic core 39. The movable iron core 36 is engaged with the flange portion provided on the outer peripheral portion of the valve rod 35. Further, one end of a switch valve urging spring abuts against the side of the movable iron core 36 opposite the magnetic core 39. The other end of the switch valve urging spring abuts against the suction valve seat 31. Further, the switch valve urging spring urges the movable iron core 36 toward the flange portion side of the valve rod 35. The movement amount of the movable iron core 36 is set to be larger than the movement amount of the suction valve 30. Thus, the suction valve 30 can be reliably brought into abutment (seating) with the seating portion, and the electromagnetic suction valve mechanism 300 can be reliably brought into a closed valve state.

[0071] An electromagnetic coil 43 is provided so as to surround the magnetic core 39 once. A terminal member 46 is electrically connected to the electromagnetic coil 43, and a current flows via the terminal member 46. In a non-energized state in which no current flows in the electromagnetic coil 43, the valve rod 35 is urged in the open valve direction by the urging force of the valve rod urging spring 40, and the suction valve 30 is pushed in the open valve direction. As a result, the suction valve 30 is separated from the seating portion and abuts against the stopper 32, and the electromagnetic suction valve mechanism 300 becomes an open valve state. That is, the electromagnetic suction valve mechanism 300 becomes a normally open type in which the valve is opened in the non-energized state.

[0072] In the open state of the electromagnetic intake valve mechanism 300, fuel from the intake port 31b flows into the pressurization chamber 11 through multiple fuel passage holes (not shown) of the stop member 32 and the intake passage 1a between the intake valve 30 and the seat portion. In the open state of the electromagnetic intake valve mechanism 300, the intake valve 30 is in contact with the stop member 32, thus restricting the position of the intake valve 30 in the opening direction. Furthermore, in the open state of the electromagnetic intake valve mechanism 300, the gap between the intake valve 30 and the seat portion constitutes the movable range of the intake valve 30, which is called the opening stroke.

[0073] When a control signal from ECU27 is applied to the electromagnetic intake valve mechanism 300, current flows through the electromagnetic coil 43 via the terminal member 46. As current flows through the electromagnetic coil 43, the movable iron core 36 on the magnetic attraction surface is attracted towards the valve closing direction by the magnetic attraction force of the magnetic core 39.

[0074] When the movable iron core 36 is attracted and moved by the magnetic core 39, it engages with the flange of the valve stem 35, and the valve stem 35 and the movable iron core 36 move together in the closing direction. As the valve stem 35 moves, the suction valve 30 moves in the opening direction (away from the seat) by the amount of the opening stroke clearance, thus entering the open state, and supplying fuel from the low-pressure fuel suction passage 10d to the pressurization chamber 11.

[0075] Furthermore, the suction valve 30 stops operating by colliding with a stop 32 that is fixed inside the housing of the electromagnetic suction valve mechanism 300. The valve stem 35 and the suction valve 30 are separate and independent structures. The suction valve 30 closes the flow path to the pressurization chamber 11 by contacting the seat portion of the suction valve seat 31 disposed on the suction side, and opens the flow path to the pressurization chamber 11 by moving away from the seat portion of the suction valve seat 31.

[0076] Next, the discharge valve mechanism 8 will be explained.

[0077] like Figure 3 As shown, the discharge valve mechanism 8 is connected to the outlet side of the pressurization chamber 11. This discharge valve mechanism 8 includes a discharge valve seat member 8a and a discharge valve 8b that is in contact with and separates from the discharge valve seat member 8a. Additionally, the discharge valve mechanism 8 includes a discharge valve spring 8c that applies force to the discharge valve 8b towards the discharge valve seat member 8a, a plug 8d, and a discharge valve stop 8e that determines the stroke (travel distance) of the discharge valve 8b.

[0078] The discharge valve seat component 8a, discharge valve 8b, discharge valve spring 8c, and discharge valve stop 8e are housed in a discharge valve chamber 12a formed on the pump body 1. The discharge valve chamber 12a is a generally cylindrical space extending horizontally. One end of the discharge valve chamber 12a communicates with the pressurization chamber 11 via a fuel passage. The other end of the discharge valve chamber 12a opens on the side of the pump body 1. At the other end of the discharge valve chamber 12a, a plug 8d is fixed by welding, for example at the weld 401. Therefore, the opening at the other end of the discharge valve chamber 12a is sealed by the plug 8d.

[0079] Additionally, a discharge connector 12 is welded to the pump body 1 via a welded portion 401. The discharge connector 12 has a fuel discharge port 12c. The fuel discharge port 12c communicates with the discharge valve chamber 12a via a discharge passage 12b extending horizontally inside the pump body 1. Furthermore, the fuel discharge port 12c of the discharge connector 12 is connected to the common rail 23.

[0080] When the fuel pressure in the pressurization chamber 11 is lower than the fuel pressure in the discharge valve chamber 12a, the differential pressure acting on the discharge valve 8b and the force of the discharge valve spring 8c press the discharge valve 8b against the discharge valve seat member 8a. As a result, the discharge valve mechanism 8 is in a closed state. On the other hand, if the fuel pressure in the pressurization chamber 11 is greater than the fuel pressure in the discharge valve chamber 12a, and the differential pressure acting on the discharge valve 8b is greater than the force of the discharge valve spring 8c, the discharge valve 8b is pushed away from the discharge valve seat member 8a by the fuel. As a result, the discharge valve mechanism 8 is in an open state.

[0081] When the discharge valve mechanism 8 operates to open and close the valve, fuel enters and exits the discharge valve chamber 12a. Furthermore, the fuel discharged from the discharge valve chamber 12a is discharged through the discharge valve mechanism 8 into the discharge passage 12b. As a result, the high-pressure fuel in the pressurization chamber 11 passes through the discharge valve chamber 12a, the discharge passage 12b, and the fuel outlet 12c of the discharge connector 12 towards the common rail 23 (see reference). Figure 1 Discharge. With the above configuration, the discharge valve mechanism 8 functions as a check valve that restricts the direction of fuel flow.

[0082] Furthermore, the detailed structure of the discharge valve spring 8c will be described later.

[0083] [Fuel pump operation]

[0084] Next, the operation of the high-pressure fuel pump 100 in this embodiment will be explained.

[0085] exist Figure 1When the plunger 2 descends, if the electromagnetic intake valve mechanism 300 opens, fuel flows from the intake passage 1a into the pressurization chamber 11. Hereinafter, the stroke of the plunger 2 descending will be referred to as the intake stroke. On the other hand, when the plunger 2 rises, if the electromagnetic intake valve mechanism 300 closes, the fuel in the pressurization chamber 11 is pressurized and discharged through the discharge valve mechanism 8 to the common rail 23 (see reference). Figure 1 ) Compression. Hereinafter, the upward stroke of plunger 2 will be referred to as the compression stroke.

[0086] As described above, if the electromagnetic intake valve mechanism 300 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 23 side. On the other hand, if the electromagnetic intake valve mechanism 300 opens during the compression stroke, the fuel in the pressurization chamber 11 is pushed back towards the intake passage 1a side and is not discharged towards the common rail 23 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 300. Moreover, the opening and closing of the electromagnetic intake valve mechanism 300 is controlled by the ECU 27.

[0087] 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 2 When the pressure difference between the two is low, and the force generated exceeds the force generated by the suction valve spring 33, the suction valve 30 moves away from the seat, and the electromagnetic suction valve mechanism 300 becomes open. As a result, fuel flows into the pressurization chamber 11 through the space between the suction valve 30 and the seat, and through multiple holes provided on the stop member 32.

[0088] After the intake stroke ends, the high-pressure fuel pump 100 enters the compression stroke. At this time, the solenoid coil 43 remains de-energized, and no magnetic attraction exists between the movable iron core 36 and the magnetic core 39. The valve stem force spring 40 is configured to have sufficient force to maintain the intake valve 30 in the open position away from the seat when de-energized.

[0089] In this state, even as the plunger 2 moves upward, the valve stem 35 remains in the open position, and therefore the suction valve 30, which is exerted by the valve stem 35, 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 sucked into the pressurization chamber 11 returns to the low-pressure fuel suction passage 10d via the open-valve electromagnetic suction valve mechanism 300, and the pressure inside the pressurization chamber 11 does not rise. This stroke is called the return stroke.

[0090] During the return stroke, when an application of force from ECU27 (refer to) is applied to the electromagnetic suction valve mechanism 300... Figure 1When the control signal of the solenoid 43 is applied, current flows through the solenoid 43 via the terminal member 46. When current flows through the solenoid 43, magnetic attraction force acts on the magnetic attraction surface S of the movable core 36 and the magnetic core 39, and the movable core 36 is attracted to the magnetic core 39. Further, when the magnetic attraction force is greater than the force of the valve rod biasing spring 40, the movable core 36 moves against the force of the valve rod biasing spring 40 to the side of the magnetic core 39, and the valve rod 35 engaged with the movable core 36 moves in the direction away from the intake valve 30. As a result, the intake valve 30 is seated in the seating portion by the force of the intake valve biasing spring 33 and the fluid force generated by the fuel flowing into the low-pressure fuel intake passage 10d, and the electromagnetic intake valve mechanism 300 becomes a closed valve state.

[0091] After the electromagnetic intake valve mechanism 300 becomes a closed valve state, the fuel of the pressure chamber 11 is pressurized along with the rising of the plunger 2, and when the pressure becomes equal to or higher than the pressure of the fuel discharge port 12c, the high-pressure fuel is discharged to the common rail 23 (see FIG. 1) through the discharge valve mechanism 8. This stroke is referred to as a discharge stroke. That is, the compression stroke of the plunger 2 from the bottom dead center to the top dead center is composed of the return stroke and the discharge stroke. Further, by controlling the timing of energization of the solenoid 43 of the electromagnetic intake valve mechanism 300, it is possible to control the amount of high-pressure fuel discharged. Figure 1

[0092] If the timing of energization of the solenoid 43 is advanced, the proportion of the return stroke in the compression stroke becomes smaller, and the proportion of the discharge stroke becomes larger. As a result, the fuel returning to the low-pressure fuel intake passage 10d becomes less, and the high-pressure fuel discharged becomes more. On the other hand, if the timing of energization of the solenoid 43 is delayed, the proportion of the return stroke in the compression stroke becomes larger, and the proportion of the discharge stroke becomes smaller. As a result, the fuel returning to the low-pressure fuel intake passage 10d becomes more, and the high-pressure fuel discharged becomes less. In this way, by controlling the timing of energization of the solenoid 43, it is possible to control the amount of high-pressure fuel discharged to the amount required by the engine (internal combustion engine).

[0093] 2. Configuration of the retainer

[0094] Next, the detailed configuration of the retainer 15 will be described with reference to Figures 5 to 12A The detailed configuration of the retainer 15 will be described.

[0095] Figure 5 is an enlarged sectional view of the retainer 15 and the plunger 2, Figure 6 is a perspective view of the retainer 15. Figure 7 is a plan view of the retainer 15, Figure 8 is a front view of the retainer 15.

[0096] Here, as Figure 5 ​As shown, a necked portion 2d is formed at an axially lower end portion 2c of the plunger 2. The lower end portion 2c abuts against the tappet 92. The necked portion 2d is formed at the small diameter portion 2b side than the lower end portion 2c. The diameter of the necked portion 2d is formed smaller than that of the lower end portion 2c. A retainer 15 is attached to the lower end portion 2c of the plunger 2.

[0097] As shown, the retainer 15 has a flat portion 16 formed in a substantially circular plate shape, a stepped portion 17, and a flange portion 18. The stepped portion 17 is continuously formed from an outer edge portion of the flat portion 16 in a radial direction. The stepped portion 17 is bent substantially perpendicularly from the outer edge portion of the flat portion 16. The flange portion 18 is continuously provided at an end portion of the stepped portion 17 opposite to the flat portion 16. The flat portion 16 and the flange portion 18 are connected by the stepped portion 17. The flange portion 18 is bent substantially perpendicularly from the stepped portion 17. Further, the flange portion 18 and the flat portion 16 are disposed substantially in parallel. Figure 6 As shown, the lower end portion of the spring 4 is placed on the flange portion 18. Further, the flat portion 16 and the stepped portion 17 are inserted into the inside of the spring 4. At this time, the stepped portion 17 opposes the inner peripheral wall of the spring 4.

[0098] Figure 5 As shown, the lower end portion of the spring 4 is placed on the flange portion 18. Further, the flat portion 16 and the stepped portion 17 are inserted into the inside of the spring 4. At this time, the stepped portion 17 opposes the inner peripheral wall of the spring 4.

[0099] Further, a mounting portion 19 is formed on the retainer 15, which is mounted on the lower end portion 2c of the plunger 2. The mounting portion 19 is formed by continuously cutting from the outer edge portion of the flange portion 18 to the center portion of the flat portion 16. The mounting portion 19 has an engaging portion 19a, a guide portion 19b, and a connecting portion 19c connecting the engaging portion 19a and the guide portion 19b.

[0100] The engaging portion 19a is continuously formed in a straight line from the outer edge portion to the center portion of the flat portion 16. The opening width of the engaging portion 19a is formed smaller than the diameter of the lower end portion 2c of the plunger 2. The necked portion 2d of the plunger 2 is engaged with this engaging portion 19a. The connecting portion 19c is continuously formed from the outer edge portion of the flat portion 16 of the engaging portion 19a. As shown, the connecting portion 19c is formed at a right angle with respect to the straight line portion of the engaging portion 19a toward the center portion of the flat portion 16. Further, the connecting portion 19c is formed on the flat portion 16 which is in the same plane as the engaging portion 19a. Figure 7 Figure 8 The guide portion 19b is continuously formed from the outer edge portion of the flange portion 18 to a part of the stepped portion 17, which is continuous with the connecting portion 19c. Further, the guide portion 19b guides the necked portion 2d toward the engaging portion 19a when the retainer 15 is mounted to the plunger 2. Further, the guide portion 19b is formed in a tapered shape whose opening width is widened toward the outer edge portion of the flange portion 18 from the stepped portion 17. Further, the length of the opening width of the guide portion 19b is set larger than the diameter of the lower end portion 2c of the plunger 2.

[0101] The guide portion 19b is continuously formed from the outer edge portion of the flange portion 18 to a part of the stepped portion 17, which is continuous with the connecting portion 19c. Further, the guide portion 19b guides the necked portion 2d toward the engaging portion 19a when the retainer 15 is mounted to the plunger 2. Further, the guide portion 19b is formed in a tapered shape whose opening width is widened toward the outer edge portion of the flange portion 18 from the stepped portion 17. Further, the length of the opening width of the guide portion 19b is set larger than the diameter of the lower end portion 2c of the plunger 2. ​​

[0102] Furthermore, by forming the guide portion 19b into a cone shape, the plunger 2 can be smoothly inserted into the mounting portion 19 of the retainer 15. While an example of forming the guide portion 19b into a cone shape has been described, it is not limited to this and can also be formed into a straight shape. At least the opening width of the guide portion 19b should be larger than the diameter of the lower end 2c of the plunger 2.

[0103] like Figure 7 As shown, the diameter D1 of the circle formed by the two ends Q2 of the engaging portion 19a (i.e., the connecting portion 19c side of the engaging portion 19a) and the point Q1 where they contact the plunger 2 on the inner peripheral wall of the spring 4 is smaller than the diameter of the lower end 2c of the plunger 2. This prevents the engaging portion 19a from disengaging from the constricted neck 2d of the plunger 2, and prevents the retainer 15 from falling off the plunger 2.

[0104] In addition, an example was described in which the connecting portion 19c is formed at a right angle to the engaging portion 19a and is formed on the plane portion 16 which is on the same plane as the engaging portion 19a. However, it is not limited to this. The connecting portion 19c may also be formed in a conical shape and extended to the flange portion 18.

[0105] Here, as Figure 7 As shown by the dashed line A1, when the connecting portion 19c is formed into a conical shape, the diameter D2 of the circle formed by the connecting portion 19c and the inner peripheral wall of the spring 4 becomes larger. Therefore, the retainer 15 may detach from the plunger 2. In contrast, by forming the connecting portion 19c formed at the end of the engaging portion 19a at a right angle relative to the engaging portion 19a, the diameter D1 of the circle formed by the corner of the engaging portion 19a and the inner peripheral wall of the spring 4 can be reduced.

[0106] Furthermore, as shown in line B1, when the connecting portion 19c is formed into a cone shape and extended to the stepped portion 17 and the flange portion 18, the diameter of the circle formed by the corner of the engaging portion 19a and the inner peripheral wall of the spring 4 can be smaller than the diameter of the lower end portion 2c. However, the opening width of the guide portion 19b becomes narrower, and the lower end portion 2c will interfere with the guide portion 19b or the connecting portion 19c, resulting in poor assemblability, or the retainer 15 may no longer be able to be mounted on the plunger 2.

[0107] Figure 9 and Figure 10 This diagram shows the state in which the retainer 15 is mounted on the plunger 2. The connecting portion 19c, formed at the end of the engaging portion 19a, is formed at a right angle relative to the engaging portion 19a. The connecting portion 19c is formed on the same plane portion 16 as the engaging portion 19a, thus, as... Figure 9 As shown, this ensures that the width of the opening of the guide portion 19b is sufficiently larger than the diameter of the lower end portion 2c. Therefore, as... Figure 10As shown, the plunger 2 can be inserted laterally into the mounting portion 19 of the retainer 15 from a direction orthogonal to its axial direction. As a result, the retainer 15 can be easily mounted on the plunger 2.

[0108] In this way, the connecting portion 19c can also be formed into a cone shape and extended to the flange portion 18. However, the connecting portion 19c is preferably formed at a right angle to the engaging portion 19a and is formed on the planar portion 16 which is on the same plane as the engaging portion 19a.

[0109] Figure 11 This is a cross-sectional view showing the relationship between the clearances of the retainer 15, the plunger 2, and the spring 4. For example... Figure 11 As shown, the gap D3 between the lower end 2c of the plunger 2 and the inner peripheral wall of the spring 4 constitutes the eccentricity between the plunger 2 and the spring 4. Furthermore, when the plunger 2 and the spring 4 abut, the inner peripheral wall of the spring 4 abuts against the outer peripheral surface of the stepped portion 17 of the retainer 15. The gap D4 between the inner peripheral wall of the spring 4 and the outer peripheral surface of the stepped portion 17 of the retainer 15 constitutes the eccentricity of the retainer 15 relative to the spring 4. Therefore, the maximum eccentricity of the retainer 15 relative to the plunger 2 is the length encompassing both gaps D3 and D4.

[0110] Figure 12A and Figure 12B This is a diagram showing the eccentric state of the retainer 15.

[0111] like Figure 12A As shown, the length D5 of the straight portion of the engaging portion 19a, that is, the length from the center of the planar portion 16 to the connecting portion 19c, is a length that allows it to engage with the constricted neck 2d of the engaging portion 19a. This length D5 of the engaging portion 19a is set to be longer than the combined length of the gaps D3 and D4. Therefore, as... Figure 12A and Figure 12B As shown, even when the retainer 15 is eccentric to the maximum extent, the engaging portion 19a of the retainer 15 abuts against the lower end 2c of the plunger 2. Thus, even before the retainer 15 is housed in the push rod 92, it is possible to prevent the retainer 15 from falling off the plunger 2.

[0112] Figure 13 This is a longitudinal cross-sectional view showing other examples of high-pressure fuel pumps.

[0113] exist Figure 13 In the high-pressure fuel pump shown, tappet 92A is... Figure 2 The pushrod 92 shown is enlarged. Therefore, the clearance between the pushrod 92A and the retainer 15 is increased. Figure 2 The example shown has a large gap. However, as mentioned above, the retainer 15 in this example will not detach from the plunger 2 even before being housed in the push rods 92, 92A.

[0114] Thus, the same retainer 15 can be used without redesigning the retainer 15 for different sizes of the tappet 92, 92A. As a result, even in the case where the tappet is upsized due to a customer request for high fuel pressure, the retainer 15 can be used even if the gap between the retainer 15 and the tappet is large, and parts commonality can be achieved, which can greatly reduce development man-hours and costs.

[0115] The above describes the embodiment of the fuel pump of the application, including the effects thereof. However, the fuel pump of the application is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the application described in the claims. In addition, the above-described embodiment is a detailed description for the purpose of easily understanding the application, and is not necessarily limited to the mode having all the described configurations.

[0116] Symbol explanation

[0117] 1 pump body, la suction passage, lc fixed portion, le flange, 2 plunger, 2a large diameter portion, 2b small diameter portion, 2c lower end portion, 2d necked portion, 4 spring, 6 cylinder, 7 seal holder, 7a auxiliary chamber, 8 discharge valve mechanism, 9 pressure pulsation reduction mechanism, 10 low pressure fuel chamber, 11 pressurizing chamber, 12 discharge joint, 12a discharge valve chamber, 12b discharge passage, 15 retainer, 16 flat portion, 17 step portion, 18 flange portion, 19 mounting portion, 19a engagement portion, 19b guide portion, 19c connecting portion, 20 fuel tank, 21 feed pump, 23 common rail, 24 injector, 26 fuel pressure sensor, 27 ECU, 28 fuel pipe, 30 suction valve, 31 suction valve seat, 32 stopper, 33 suction valve urging spring, 40 valve rod urging spring, 41 open / close valve urging spring, 92, 92A tappet, 93 cam, 100 high pressure fuel pump, 200 spill valve mechanism, 300 solenoid suction valve mechanism

Claims

1. A fuel pump characterized by comprising: Possessing: a plunger that reciprocates; a retainer that has a mounting portion mounted to a lower end portion of the plunger; and a spring that exerts a force on the plunger via the retainer, the mounting portion of the retainer has an engaging portion that engages with a necked-down portion formed in the lower end portion of the plunger and a guide portion that guides the necked-down portion toward the engaging portion, the mounting portion is formed by continuous cutouts from an outer edge portion of the retainer to a central portion of the retainer, a length of a width of an opening in the engaging portion is formed to be smaller than a diameter of the lower end portion of the plunger, and a length of a width of an opening in the guide portion is formed to be larger than the diameter of the lower end portion of the plunger, a diameter of a circle formed by a corner portion of the guide portion side of the engaging portion and an inner peripheral wall of the spring is smaller than the diameter of the lower end portion of the plunger.

2. The fuel pump according to claim 1, wherein the retainer includes: a flat portion that is formed with the engaging portion; a step portion that is continuous from an outer edge portion of the flat portion; and a flange portion that is continuous from an end portion of the step portion on a side opposite the flat portion, on which the spring is placed, the guide portion is formed in the flange portion.

3. The fuel pump according to claim 2, wherein the mounting portion has a connecting portion that connects the engaging portion and the guide portion.

4. The fuel pump according to claim 3, wherein the engaging portion is formed in a straight line shape from a central portion to an outer edge portion of the flat portion, the connecting portion is formed at a right angle with respect to the engaging portion, the guide portion is formed in a tapered shape in which a width of an opening widens as it goes from the connecting portion toward an outer edge portion of the flange portion.

5. The fuel pump according to claim 3, wherein the connecting portion is formed in the flat portion that is in the same plane as the engaging portion.

6. The fuel pump according to claim 2, wherein the flat portion and the step portion are inserted inside the spring, a length of the engaging portion that can engage with the necked-down portion is set to be longer than a length that is a sum of a gap between the lower end portion of the plunger and the inner peripheral wall of the spring and a gap between the inner peripheral wall of the spring and an outer peripheral surface of the step portion.

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