WO2023209949A1

WO2023209949A1 - Fuel pump

Info

Publication number: WO2023209949A1
Application number: PCT/JP2022/019280
Authority: WO
Inventors: 悠登石塚; 裕之山田; 稔橋田; 悟史臼井
Original assignee: 日立Astemo株式会社
Priority date: 2022-04-28
Filing date: 2022-04-28
Publication date: 2023-11-02

Abstract

The present invention provides a fuel pump that supplies fuel to a side having lower pressure than a seal member, which is prone to insufficient fuel supply, that achieves higher efficiency for a discharge flow rate, and that can prevent sticking of a plunger. The fuel pump comprises a seal member 20 that is disposed in an annular groove 2r provided in a sliding surface of a plunger 2, and that makes contact with a sliding surface of a cylinder 6. The annular groove 2r and the seal member 20 are provided between a compression chamber 11 and an auxiliary chamber 17a. The cylinder 6 has a communication hole (fuel supply hole 6d) that is connected to the auxiliary chamber 17a, on the cylinder sliding surface further to the auxiliary chamber 17a side than the seal member 20 in the axial direction of the plunger 2.

Description

Fuel pump

The present invention relates to a fuel pump that supplies high-pressure fuel to an engine.

The fuel pump is described in Patent Document 1, for example. The high-pressure fuel supply pump described in Patent Document 1 has a cylindrical space that accommodates a cylinder that slidably holds a plunger attached to a pump body and that forms a pressurizing chamber. The plunger moves up and down due to the rotation of a cam attached to the engine's camshaft, sucking in and discharging fuel. A seal member is attached to the plunger to prevent high-pressure fuel from leaking to the low-pressure side, thereby increasing the efficiency of the discharge flow rate.

International Publication No. 2018/009390

However, in the high-pressure fuel supply pump described in Patent Document 1, the seal member blocks the high-pressure fuel from leaking to the low-pressure side, so that the low-pressure side is more likely to be short of fuel supply than the seal member, and the oil film runs out. There was a problem in which the plunger became stuck (seized) to the cylinder.

In consideration of the above-mentioned problems, an object of the present invention is to supply fuel to a lower pressure side than a sealing member that is prone to insufficient fuel supply, to achieve high efficiency in discharge flow rate, and to prevent sticking of a plunger. Our goal is to provide fuel pumps that can.

In order to solve the above problems and achieve the objects of the present invention, the fuel pump of the present invention includes a plunger, a cylinder that guides the reciprocating motion of the plunger, and a cylinder that communicates with a pressurizing chamber and into which the cylinder is inserted. a pump body provided with an insertion hole; a sub-chamber provided on the opposite side of the plunger to the pressurizing chamber and containing low-pressure fuel; and a first annular groove provided in the sliding surface of the plunger. a sealing member disposed in the cylinder and in contact with the sliding surface of the cylinder, the first annular groove and the sealing member being provided between the pressurizing chamber and the auxiliary chamber, and the cylinder , a communication hole connected to the sub-chamber is provided on a cylinder sliding surface closer to the sub-chamber than the seal member in the axial direction of the plunger.

According to the fuel pump of the present invention, even when high-pressure fuel is cut off by the seal member, it is possible to form a fuel oil film on the sliding portion, and it is possible to prevent the plunger from sticking.

Problems, configurations, and effects other than those described above will be made clear by the description of the embodiments below.

1 is an overall configuration diagram of a fuel supply system using a high-pressure fuel supply pump according to an embodiment of the present invention. FIG. 1 is a vertical cross-sectional view (part 1) of a high-pressure fuel supply pump according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view (part 2) of the high-pressure fuel supply pump according to an embodiment of the present invention. 1 is a horizontal cross-sectional view of a high-pressure fuel supply pump according to an embodiment of the present invention, viewed from above. FIG. 3 is a vertical cross-sectional view (part 3) of the high-pressure fuel supply pump according to an embodiment of the present invention. FIG. 2 is an enlarged longitudinal cross-sectional view of a main part of a plunger and a cylinder surrounding area of a high-pressure fuel supply pump according to an embodiment of the present invention. FIG. 7 is an enlarged vertical cross-sectional view of another example of the main parts of the plunger and cylinder peripheral portion of the high-pressure fuel supply pump according to an embodiment of the present invention.

Hereinafter, a high-pressure fuel supply pump according to an embodiment of the present invention will be described. Note that common members in each figure are given the same reference numerals.

[Fuel supply system]
First, a fuel supply system using a high-pressure fuel supply pump (fuel pump) according to the present embodiment will be described using FIG. 1.

FIG. 1 is an overall configuration diagram of a fuel supply system using a high-pressure fuel supply pump according to this embodiment.

As shown in FIG. 1, 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 a plurality of injectors 107. . The parts of the high-pressure fuel supply pump 100 are integrated into the pump body 1.

Fuel in the fuel tank 103 is pumped up by a feed pump 102 that is driven based on a signal from the ECU 101. The pumped fuel is pressurized to an appropriate pressure by a pressure regulator (not shown), and is sent to the low-pressure fuel inlet 51 of the high-pressure fuel supply pump 100 through the low-pressure pipe 104.

The high-pressure fuel supply pump 100 pressurizes the fuel supplied from the fuel tank 103 and pumps it to the common rail 106. A plurality of injectors 107 and a fuel pressure sensor 105 are attached to the common rail 106. The plurality of injectors 107 are installed according to 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 injector 107 injects fuel directly into the cylinder of the engine.

The fuel pressure sensor 105 outputs detected pressure data to the ECU 101. The ECU 101 determines an appropriate amount of injected fuel (target injection fuel length) and appropriate fuel pressure (target (fuel pressure), etc.

Furthermore, the ECU 101 controls the driving of the high-pressure fuel supply pump 100 and the plurality of injectors 107 based on calculation results such as fuel pressure (target fuel pressure). That is, ECU 101 includes a pump control section that controls high-pressure fuel supply pump 100 and an injector control section that controls injector 107.

The high-pressure fuel supply pump 100 includes a pressure pulsation reduction mechanism 9, an electromagnetic suction valve 3 that is a variable capacity mechanism, a relief valve 4 (see FIG. 2), and a discharge valve 8. Fuel flowing in from the low-pressure fuel intake port 51 reaches the intake port 31b of the electromagnetic intake valve 3 via the pressure pulsation reduction mechanism 9 and the intake passage 10b.

The fuel that has flowed into the electromagnetic suction valve 3 passes through the valve portion 32, flows through the suction passage 1d formed in the pump body 1, and then flows into the pressurizing chamber 11. A plunger 2 is inserted into the pressurizing chamber 11 so as to be able to reciprocate. The plunger 2 reciprocates as power is transmitted by a cam 91 of the engine (see FIG. 2).

In the pressurizing chamber 11, fuel is sucked in from the electromagnetic intake valve 3 during the downward stroke of the plunger 2, and the fuel is pressurized during the upward stroke. When the fuel pressure in the pressurizing chamber 11 exceeds a predetermined value, the discharge valve 8 opens and high-pressure fuel is force-fed to the common rail 106 through the discharge passage 12a. The discharge of fuel by the high-pressure fuel supply pump 100 is controlled by opening and closing the electromagnetic intake valve 3. The opening and closing of the electromagnetic intake valve 3 is controlled by the ECU 101.

[High pressure fuel supply pump]
Next, the configuration of the high-pressure fuel supply pump 100 will be explained using FIGS. 2 to 5.

FIG. 2 is a vertical cross-sectional view (part 1) of the high-pressure fuel supply pump 100 taken in a cross section perpendicular to the horizontal direction. FIG. 3 is a vertical cross-sectional view (part 2) of the high-pressure fuel supply pump 100 taken in a cross section perpendicular to the horizontal direction. FIG. 4 is a horizontal cross-sectional view of the high-pressure fuel supply pump 100 taken along a cross section perpendicular to the vertical direction. Further, FIG. 5 is a vertical cross-sectional view (No. 3) of the high-pressure fuel supply pump 100 taken in a cross section perpendicular to the horizontal direction.

As shown in FIGS. 2 to 5, the pump body 1 of the high-pressure fuel supply pump 100 is formed into a substantially cylindrical shape. As shown in FIGS. 2 and 3, the pump body 1 is provided with a first chamber 1a, a second chamber 1b, a third chamber 1c, and a suction passage 1d. Further, the pump body 1 is in close contact with the fuel pump mounting portion 90 and is fixed with a plurality of bolts (screws) not shown.

The first chamber 1a is a cylindrical space provided in the pump body 1, and the centerline 1A of the first chamber 1a coincides with the centerline 1A 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 pressurizing chamber 11.

The second chamber 1b is a cylindrical space provided in the pump body 1, and the center line of the second chamber 1b is perpendicular to the center line 1A of the pump body 1 (first chamber 1a). A relief valve 4 is arranged in this second chamber 1b. Note that the diameter of the second chamber 1b is smaller than the diameter of the first chamber 1a.

Furthermore, the first chamber 1a and the second chamber 1b communicate with each other through a circular communication hole 1e. The diameter of the communication hole 1e is the same as the diameter of the first chamber 1a, and the communication hole 1e extends one end of the first chamber 1a. The diameter of the communication hole 1e is larger than the outer diameter of the plunger 2. The center line of the communication hole 1e is perpendicular to the center line of the second chamber 1b.

As shown in FIGS. 3 and 5, the diameter of the communication hole 1e is larger than the diameter of the second chamber 1b. The communication hole 1e has a tapered surface 1f whose diameter decreases toward the second chamber 1b in a cross section perpendicular to the center line of the second chamber 1b. Thereby, the fuel that has passed through the relief valve 4 disposed in the second chamber 1b can smoothly return to the pressurizing chamber 11 along the tapered surface 1f.

The third chamber 1c is a cylindrical space provided in the pump body 1, and is continuous with the other end of the first chamber 1a. The center line 1A of the third chamber 1c coincides with the center line 1A of the first chamber 1a and the center line 1A 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 that guides the reciprocating movement of the plunger 2 is arranged in the third chamber 1c. That is, the third chamber 1c serves as a cylinder insertion hole into which the cylinder 6 is inserted.

The cylinder 6 is formed into a cylindrical shape, and has a press-fitting part 6a (see FIGS. 6 and 7) with the largest outer diameter in the middle thereof. The outer peripheral side of the cylinder 6 is press-fitted into the third chamber 1c of the pump body 1 at a press-fitting part 6a, and one end of the cylinder 6 is connected to the top surface of the third chamber 1c (first chamber 1a and third chamber 1c). The stepped part between the In the cylinder 6, only the press-fitting part 6a has a press-fitting dimension, and the diameter of the press-fitting part 6a on the pressurizing chamber 11 side (one end side) is set smaller than that of the press-fitting part 6a, and the diameter of the press-fitting part 6a on the pressurizing chamber 11 side (one end side) is set smaller than the press-fitting part 6a. There is an annular clearance (gap) between them. The plunger 2 is in slidable contact with the inner peripheral surface of the cylinder 6.

An O-ring 93, which is a specific example of a seat member, is interposed between the fuel pump mounting portion 90 and the pump body 1. This O-ring 93 prevents engine oil from leaking to the outside of the engine (internal combustion engine) through between the fuel pump mounting portion 90 and the pump body 1.

A tappet 92 is provided at the lower end of the plunger 2 to convert the rotational motion of a cam 91 attached to the camshaft of the engine into vertical motion and transmit it to the plunger 2. The plunger 2 is urged toward the cam 91 by a spring 16 via a retainer 15, and is pressed against a tappet 92. The tappet 92 reciprocates as the cam 91 rotates. The plunger 2 reciprocates together with the tappet 92 to change the volume of the pressurizing chamber 11.

Furthermore, a seal holder 17 is arranged between the cylinder 6 and the retainer 15. The seal holder 17 is formed into a cylindrical shape into which the plunger 2 is inserted, and has a subchamber 17a at the upper end on the cylinder 6 side. The auxiliary chamber 17a is continuous with the lower end of the third chamber 1c where the cylinder 6 is arranged. That is, the auxiliary chamber 17a is provided at a position opposite to the pressurizing chamber 11 (first chamber 1a side) of the plunger 2. Further, the seal holder 17 holds a plunger seal 18 at a lower end portion on the retainer 15 side.

The plunger seal 18 is in slidable contact with the outer periphery of the plunger 2, and when the plunger 2 moves back and forth, it seals the fuel in the subchamber 17a and prevents the fuel in the subchamber 17a from flowing into the engine. There is. Further, the plunger seal 18 prevents lubricating oil (including engine oil) that lubricates sliding parts within the engine from flowing into the inside of the pump body 1.

In FIG. 2, the plunger 2 reciprocates in the vertical direction. When the plunger 2 descends, the volume of the pressurizing chamber 11 increases, and when the plunger 2 ascends, the volume of the pressurizing chamber 11 decreases. That is, the plunger 2 is arranged so as to reciprocate in the direction of expanding and contracting the volume of the pressurizing chamber 11.

The plunger 2 is formed into a stepped cylindrical shape extending along the center line 1A (axial direction) of the pump body 1. That is, the center line 1A (axial direction) of the plunger 2 coincides with the center line 1A of the pump body 1, and the plunger 2 reciprocates along the center line 1A (axial direction). The plunger 2 has a large diameter portion 2a and a small diameter portion 2b. The outer peripheral surface of the large diameter portion 2a of the plunger 2 is in slidable contact with the inner peripheral surface of the cylinder 6. When the plunger 2 reciprocates, the large diameter portion 2a, the small diameter portion 2b, and the stepped portion 2c between the large diameter portion 2a and the small diameter portion 2b are located in the subchamber 17a. Therefore, the volume of the subchamber 17a is increased or decreased (varied) by the reciprocating motion of the plunger 2.

The auxiliary chamber 17a communicates with the low-pressure fuel chamber 10 through a fuel passage 10c (see FIG. 5). In other words, the subchamber 17a accommodates low pressure fuel. The fuel passage 10c is provided in the pump body 1 so as to pass through the outer peripheral side of the cylinder 6 (third chamber 1c) in the vertical direction (parallel to the center line 1A of the pump body 1). Through this fuel passage 10c, when the plunger 2 descends, fuel flows from the sub-chamber 17a to the low-pressure fuel chamber 10, and when the plunger 2 ascends, fuel flows from the low-pressure fuel chamber 10 to the sub-chamber 17a. do. Thereby, the fuel flow rate in and out of the pump during the suction stroke or return stroke of the high-pressure fuel supply pump 100 can be reduced, and pressure pulsations occurring inside the high-pressure fuel supply pump 100 can be reduced.

Details around the plunger 2 and cylinder 6 will be explained using FIG. 6. FIG. 6 is an enlarged longitudinal cross-sectional view of the main parts of the vicinity of the plunger 2 and cylinder 6 of the high-pressure fuel supply pump 100.

In the sliding portion between the plunger 2 and the cylinder 6, a flow of highly pressurized fuel from the pressurizing chamber 11 side to the auxiliary chamber 17a side occurs during the pressurizing stroke. Conventionally, during the pressurization stroke, high-pressure fuel flows into the sliding parts of the plunger 2 and cylinder 6, forming an oil film of fuel between the plunger 2 and cylinder 6, which prevents the plunger 2 from sticking to the cylinder 6. Was. However, as the pressure has increased in recent years, the flow of high-pressure fuel from the pressurizing chamber 11 to the auxiliary chamber 17a has increased, and there is a possibility that the discharge flow rate may be insufficient. Therefore, a sealing member 20 that seals high-pressure fuel is placed in the plunger 2 or the cylinder 6 at the sliding portion between the plunger 2 and the cylinder 6 to prevent the discharge flow rate from decreasing. However, since the high-pressure fuel was sealed, there was a risk that the plunger 2 would become stuck to the cylinder 6 due to lack of oil film in the sliding portion closer to the auxiliary chamber 17a than the seal member 20. In order to solve the above-mentioned problem, the present embodiment provides fuel supply to the sliding parts of the plunger 2 and cylinder 6 below the seal member 20, which is prone to run out of oil film even when high-pressure fuel is in a sealed state. The structure is designed to allow oil film formation.

An annular groove 2r is formed in the outer peripheral part (sliding part) of the large diameter part 2a of the plunger 2, and a ring-shaped seal member (also referred to as a seal ring) 20 is arranged in the annular groove 2r. The seal member 20 is configured to be in contact with the cylinder inner circumferential portion 6b, which is the sliding portion of the cylinder 6, between the pressurizing chamber 11 and the auxiliary chamber 17a.

A fuel supply hole 6d is formed in the cylinder 6 on the side closer to the sub-chamber 17a than the seal member 20, which is a communication hole through which the sub-chamber 17a, the plunger 2, and the sliding portion of the cylinder 6 are connected. In other words, in the cylinder 6, the fuel supply hole 6d, which is a communication hole connected to the sub-chamber 17a, is formed in the inner circumferential portion 6b of the cylinder that is closer to the sub-chamber 17a than the seal member 20 in the vertical direction. The fuel supply hole 6d is preferably formed closer to the auxiliary chamber 17a than the seal member 20 even when the plunger 2 is at the bottom dead center.

As a result, even when high-pressure fuel is cut off by the seal member 20, fuel can be supplied to the sliding portion of the plunger 2 and the cylinder 6 on the sub chamber 17a side than the seal member 20 through the fuel supply hole 6d. This makes it possible to form an oil film and prevent the plunger 2 from sticking.

In the illustrated example, the diameter of the cylinder 6 on the sub-chamber 17a side (other end side) is set smaller than that of the press-fitting part 6a, and the diameter of the cylinder 6 is set smaller than the press-fitting part 6a (on the sub-chamber 17a side than the press-fitting part 6a). 6c protrudes into the auxiliary chamber 17. The fuel supply hole 6d is provided in the reduced diameter portion 6c of the cylinder 6 so as to pass horizontally from the cylinder inner circumferential portion 6b (sliding portion side) to the outer circumferential portion (auxiliary chamber 17a side). The center line 6d is orthogonal to the center line 1A of the pump body 1. At least one fuel supply hole 6d may be formed around the center line 1A of the pump body 1 (around the axis of the plunger 2 or in the circumferential direction), but as shown in FIG. That's good. By forming the fuel supply hole 6d and the fuel passage 10c at the same position around the center line 1A of the pump body 1 (around the axis of the plunger 2 or in the circumferential direction), the fuel flow through the fuel passage 10c allows the fuel supply hole 6d to (See dotted arrow).

Note that an annular groove 6e may be formed on the inner peripheral side of the fuel supply hole 6d. In other words, the annular groove 6e connected to the fuel supply hole 6d may be formed in the cylinder inner circumferential portion 6b, which is the sliding portion of the cylinder 6. Further, the annular groove 6e may be formed to have a vertical width larger or smaller than the vertical width of the fuel supply hole 6d. Thereby, fuel can be supplied to the entire circumferential direction of the plunger 2.

Further, since the volume of the subchamber 17a is configured to change due to the reciprocating motion of the plunger 2, the fuel flow in the subchamber 17a due to the volume change of the subchamber 17a effectively supplies fuel to the fuel supply hole 6d. It becomes possible to supply In particular, since the step portion 2c of the plunger 2 is (always) located in the subchamber 17a, the step portion 2c promotes volume fluctuations in the subchamber 17a, so that fuel can be more effectively supplied to the fuel supply hole 6d. becomes possible.

Note that a fuel scraping groove (scraping groove) 2d may be provided closer to the auxiliary chamber 17a than the annular groove 2r of the outer peripheral part (sliding part) of the large diameter portion 2a of the plunger 2 and the seal member 20. The scraping groove 2d may be formed in at least a part of the circumferential direction of the plunger 2, but may be formed in an annular shape in the entire circumferential direction of the plunger 2. This scraping groove 2d is preferably formed at a position where at least a portion thereof overlaps with the fuel supply hole 6d and the annular groove 6e due to the reciprocating movement of the plunger 2 (in other words, at a position where they coincide in the movable range of the plunger 2). In the illustrated example, the scraping groove 2d is formed at a position overlapping the fuel supply hole 6d and the annular groove 6e when the plunger 2 is at the bottom dead center. Thereby, the fuel accumulated in the fuel supply hole 6d or the annular groove 6e can be supplied in the axial direction of the plunger 2, and the range in which an oil film can be formed can be further expanded.

Note that the sealing member 20 may be arranged not on the plunger 2 but on the cylinder inner peripheral portion 6b, which is the sliding portion of the cylinder 6. That is, the sealing member 20 may be interposed between the plunger 2 and the cylinder 6 so as to seal the gap between the sliding parts of the plunger 2 and the cylinder 6.

FIG. 7 is an enlarged longitudinal cross-sectional view of the main parts of another example of the vicinity of the plunger 2 and cylinder 6 of the high-pressure fuel supply pump 100.

As shown in FIG. 7, the cylinder 6 has a fuel supply hole 6g, which is a communication hole where the pressurizing chamber 11, the plunger 2, and the sliding part of the cylinder 6 are connected on the side closer to the pressurizing chamber 11 than the sealing member 20. may be formed. In other words, in the cylinder 6, the fuel supply hole 6g, which is a communication hole connected to the pressurizing chamber 11, may be formed in the inner peripheral portion 6b of the cylinder that is closer to the pressurizing chamber 11 than the seal member 20 in the vertical direction. In the illustrated example, the fuel supply hole 6g extends horizontally through a portion of the cylinder 6 closer to the pressurizing chamber 11 (one end side) than the press-fitting portion 6a (a portion disposed in the third chamber 1c of the pump body 1). The center line of the fuel supply hole 6g is perpendicular to the center line 1A of the pump body 1. At least one fuel supply hole 6g may be formed around the center line 1A of the pump body 1 (around the axis of the plunger 2 or in the circumferential direction). In the cylinder 6, a communication groove 6j is formed in the top surface 6i which is in contact with the pump body 1 on the pressurizing chamber 11 side, which communicates the inner and outer circumferences. At least one communication groove 6j may be formed around the center line 1A of the pump body 1 (around the axis of the plunger 2 or in the circumferential direction). The fuel supply hole 6g on the pressurizing chamber 11 side has a gap between the cylinder 6 (the part closer to the pressurizing chamber 11 than the press-fitting part 6a) and the third chamber 1c of the pump body 1 (an annular gap on the outer circumferential side, and It is connected to the pressurizing chamber 11 through a communication groove 6j) on the top surface 6i side. That is, it passes from the pressurizing chamber 11 through the communication groove 6j, passes through the annular gap between the outer peripheral part of the cylinder 6 (the part closer to the pressurizing chamber 11 than the press-fitting part 6a) and the third chamber 1c of the pump body 1, and passes through the pressurizing chamber 11. The configuration is such that fuel passes through the fuel supply hole 6g on the pressure chamber 11 side and is supplied to the sliding portion of the plunger 2. As a result, even when fuel lubrication is depleted due to fuel vaporization, etc., a stable oil film can be formed in the sliding portion on the pressure chamber 11 side of the seal member 20, leading to prevention of sticking of the plunger 2.

Note that, similar to the annular groove 6e on the side of the auxiliary chamber 17a, an annular groove 6h may be provided on the inner peripheral side of the fuel supply hole 6g. In other words, an annular groove 6h connected to the fuel supply hole 6g may be provided in the cylinder inner peripheral portion 6b, which is the sliding portion of the cylinder 6. Further, the vertical width of the annular groove 6h may be larger or smaller than the vertical width of the fuel supply hole 6g. Thereby, fuel can be supplied to the entire circumferential direction of the plunger 2.

Note that, similarly to the scraping groove 2g on the subchamber 17a side, there is a fuel scraping groove on the pressurizing chamber 11 side than the annular groove 2r on the outer peripheral part (sliding part) of the large diameter part 2a of the plunger 2 and the seal member 20. (Scraping groove) 2g may be provided. The scraping groove 2g may be formed in at least a part of the circumferential direction of the plunger 2, but may be formed in an annular shape in the entire circumferential direction of the plunger 2. This scraping groove 2g is preferably formed at a position where at least a portion thereof overlaps with the fuel supply hole 6g and the annular groove 6h due to the reciprocating movement of the plunger 2 (in other words, at a position where they coincide in the movable range of the plunger 2). In the illustrated example, the scraping groove 2g is formed at a position overlapping the fuel supply hole 6g and the annular groove 6h when the plunger 2 is near the top dead center. Thereby, the fuel accumulated in the fuel supply hole 6g or the annular groove 6h can be supplied in the axial direction of the plunger 2, making it possible to further expand the oil film formation range.

It should be noted that the

fuel supply holes

6d and 6g may be provided either in the vertical direction with respect to the seal member 20, or may be configured to include both.

As shown in FIG. 3, a low-pressure fuel chamber 10 is provided in the upper part of the pump body 1 of the high-pressure fuel supply pump 100, and a suction joint 5 is attached to the side surface of the pump body 1. The intake joint 5 is connected to a low pressure pipe 104 through which fuel supplied from a fuel tank 103 (see FIG. 1) passes. Fuel in the fuel tank 103 is supplied into the pump body 1 from the suction joint 5.

The suction joint 5 has a low-pressure fuel suction port 51 connected to the low-pressure pipe 104 and a suction flow path 52 communicating with the low-pressure fuel suction port 51. The fuel that has passed through the suction passage 52 passes through a suction filter 53 provided inside the pump body 1 and is supplied to the low-pressure fuel chamber 10 . The suction filter 53 removes foreign substances present in the fuel and prevents foreign substances from entering the high-pressure fuel supply pump 100.

The low pressure fuel chamber 10 is provided with a low pressure fuel passage 10a and an intake passage 10b (see FIG. 2). A pressure pulsation reduction mechanism 9 is provided in the low pressure fuel flow path 10a. When the fuel that has flowed into the pressurizing chamber 11 is returned to the suction passage 10b through the electromagnetic suction valve 3 which is in an open state again, pressure pulsations occur in the low pressure fuel chamber 10. The pressure pulsation reduction mechanism 9 reduces pressure pulsations generated within the high-pressure fuel supply pump 100 from spreading to the low-pressure piping 104.

The pressure pulsation reduction mechanism 9 is formed of a metal diaphragm damper made by laminating two corrugated disc-shaped metal plates together at their outer peripheries and injecting an inert gas such as argon into the interior. The metal diaphragm damper of the pressure pulsation reduction mechanism 9 absorbs or reduces pressure pulsations by expanding and contracting.

The suction passage 10b communicates with the suction port 31b (see FIG. 2) of the electromagnetic suction valve 3, and the fuel that has passed through the low-pressure fuel passage 10a is delivered to the suction port 31b of the electromagnetic suction valve 3 via the suction passage 10b. reach.

As shown in FIGS. 2 and 4, the electromagnetic suction valve 3 is inserted into a side hole formed in the pump body 1. The electromagnetic suction valve 3 includes a suction valve seat 31 press-fitted into a side hole formed in the pump body 1, a valve portion 32, a rod 33, a rod biasing spring 34, an electromagnetic coil 35, and an anchor 36. are doing.

The suction valve seat 31 is formed into a cylindrical shape, and a seating portion 31a is provided on the inner circumference. Further, the suction valve seat 31 is formed with a suction port 31b that reaches from the outer circumference to the inner circumference. This suction port 31b communicates with the suction passage 10b in the low pressure fuel chamber 10 described above.

A stopper 37 facing the seating portion 31a of the suction valve seat 31 is arranged in the side hole formed in the pump body 1, and the valve portion 32 is arranged between the stopper 37 and the seating portion 31a. Further, a valve biasing spring 38 is interposed between the stopper 37 and the valve portion 32. The valve biasing spring 38 biases the valve portion 32 toward the seating portion 31a.

By contacting the seating portion 31a, the valve portion 32 closes the communication portion between the suction port 31b and the pressurizing chamber 11, and the electromagnetic suction valve 3 is placed in a closed state. On the other hand, the valve portion 32 opens the communication portion between the suction port 31b and the pressurizing chamber 11 by coming into contact with the stopper 37, and the electromagnetic suction valve 3 becomes open.

The rod 33 passes through the cylindrical hole of the suction valve seat 31, and one end (inner end) is in contact with the valve portion 32. The rod biasing spring 34 biases the valve portion 32 via the rod 33 in the valve opening direction, which is the stopper 37 side. One end (inner end) of the rod biasing spring 34 is engaged with the other end (outer end) of the rod 33, and the other end (outer end) of the rod biasing spring 34 surrounds the rod biasing spring 34. The magnetic core 39 is engaged with the magnetic core 39 arranged as shown in FIG.

The anchor 36 faces the end surface of the magnetic core 39. Further, the anchor 36 is engaged with a flange provided at the intermediate portion of the rod 33. The electromagnetic coil 35 is arranged so as to go around the magnetic core 39. A terminal member 40 is electrically connected to the electromagnetic coil 35, and a current flows through the terminal member 40.

In a non-energized state where no current flows through the electromagnetic coil 35, the rod 33 is biased in the valve opening direction by the biasing force of the rod biasing spring 34, and presses the valve portion 32 in the valve opening direction. As a result, the valve portion 32 is separated from the seating portion 31a and comes into contact with the stopper 37, and the electromagnetic suction valve 3 is in an open state. That is, the electromagnetic suction valve 3 is of a normally open type, which opens in a non-energized state.

When the electromagnetic suction valve 3 is in the open state, fuel in the suction port 31b passes between the valve portion 32 and the seating portion 31a, passes through a plurality of fuel passage holes (not shown) in the stopper 37, and the suction passage 1d. It flows into the pressure chamber 11. When the electromagnetic suction valve 3 is in the open state, the valve portion 32 comes into contact with the stopper 37, so that the position of the valve portion 32 in the valve opening direction is regulated. The gap that exists between the valve portion 32 and the seating portion 31a when the electromagnetic suction valve 3 is in the open state is the movable range of the valve portion 32, and this is the valve opening stroke.

When current flows through the electromagnetic coil 35, the anchor 36 is drawn in the valve closing direction by the magnetic attraction force of the magnetic core 39. As a result, the anchor 36 moves against the biasing force of the rod biasing spring 34 and comes into contact with the magnetic core 39. When the anchor 36 moves in the valve closing direction toward the magnetic core 39, the rod 33 with which the anchor 36 engages moves together with the anchor 36. As a result, the valve portion 32 is released from the biasing force in the valve-opening direction and moves in the valve-closing direction by the biasing force of the valve biasing spring 38. Then, when the valve portion 32 comes into contact with the seating portion 31a of the suction valve seat 31, the electromagnetic suction valve 3 enters the closed state.

As shown in FIGS. 4 and 5, the discharge valve 8 is connected to the outlet side (downstream side) of the pressurizing chamber 11. The discharge valve 8 includes a discharge valve seat 81 that communicates with the pressurizing chamber 11, a valve portion 82 that comes into contact with and separates from the discharge valve seat 81, and a discharge valve spring 83 that urges the valve portion 82 toward the discharge valve seat 81. It has a discharge valve stopper 84 that determines the stroke (movement distance) of the valve portion 82.

Further, the discharge valve 8 has a plug 85 that blocks leakage of fuel to the outside. The discharge valve stopper 84 is press-fitted into the plug 85. The plug 85 is joined to the pump body 1 by welding at a welding portion 86. The discharge valve 8 communicates with a discharge valve chamber 87 that is opened and closed by a valve portion 82 . The discharge valve chamber 87 is formed in the pump body 1.

The pump body 1 is provided with a side hole that communicates with the second chamber 1b (see FIG. 2), and the discharge joint 12 is inserted into the side hole. The discharge joint 12 has the above-mentioned discharge passage 12a that communicates with the side hole of the pump body 1 and the discharge valve chamber 87, and a fuel discharge port 12b that is one end of the discharge passage 12a. The fuel discharge port 12b of the discharge joint 12 communicates with the common rail 106 (see FIG. 1). Note that the discharge joint 12 is fixed to the pump body 1 by welding through a welded portion 12c.

When there is no fuel pressure difference (fuel pressure difference) between the pressurizing chamber 11 and the discharge valve chamber 87, the valve portion 82 is pressed against the discharge valve seat 81 by the urging force of the discharge valve spring 83, and the discharge valve 8 is in a closed state. When the fuel pressure in the pressurizing chamber 11 becomes greater than the fuel pressure in the discharge valve chamber 87, the valve portion 82 moves against the biasing force of the discharge valve spring 83, and the discharge valve 8 opens. Become.

When the discharge valve 8 is in the closed state, the (high pressure) fuel in the pressurizing chamber 11 passes through the discharge valve 8 and reaches the discharge valve chamber 87. The fuel that has reached the discharge valve chamber 87 is then discharged to the common rail 106 (see FIG. 1) through the fuel discharge port 12b of the discharge joint 12. With the above configuration, the discharge valve 8 functions as a check valve that restricts the direction of fuel flow.

The relief valve 4 shown in FIG. 2 is activated when some problem occurs in the common rail 106 or a member beyond it and the pressure of the common rail 106 becomes high beyond a predetermined pressure. This valve is configured to return the pressure to the pressurizing chamber 11. This relief valve 4 is arranged at a higher position than the discharge valve 8 (see FIG. 5) in the direction in which the plunger 2 reciprocates (vertical direction).

The relief valve 4 includes a relief spring 41, a relief valve holder 42, a valve portion 43, and a seat member 44. This relief valve 4 is inserted through the discharge joint 12 and arranged in the second chamber 1b. The relief spring 41 has one end in contact with the pump body 1 (one end of the second chamber 1b), and the other end in contact with the relief valve holder 42. The relief valve holder 42 is engaged with the valve portion 43 , and the urging force of the relief spring 41 acts on the valve portion 43 via the relief valve holder 42 .

The valve portion 43 is pressed by the urging force of the relief spring 41 and closes the fuel passage of the seat member 44. The moving direction of the valve portion 43 (relief valve holder 42) is orthogonal to the direction in which the plunger 2 reciprocates. The center line of the relief valve 4 (the center line of the relief valve holder 42) is perpendicular to the center line of the plunger 2.

The seat member 44 has a fuel passage facing the valve part 43, and the side of the fuel passage opposite to the valve part 43 communicates with the discharge passage 12a. Movement of fuel between the pressurizing chamber 11 (upstream side) and the seat member 44 (downstream side) is blocked by the valve portion 43 coming into contact with (adhering to) the seat member 44 to close the fuel passage.

When the pressure inside the common rail 106 and the members beyond it increases, the fuel on the seat member 44 side presses the valve part 43 and moves the valve part 43 against the biasing force of the relief spring 41. As a result, the valve portion 43 opens, and the fuel in the discharge passage 12a returns to the pressurizing chamber 11 through the fuel passage of the seat member 44. Therefore, the pressure that causes the valve portion 43 to open is determined by the biasing force of the relief spring 41.

The moving direction of the valve part 43 (relief valve holder 42) in the relief valve 4 is different from the moving direction of the valve part 82 in the discharge valve 8 described above. That is, the moving direction of the valve part 82 in the discharge valve 8 is the first radial direction of the pump body 1, and the moving direction of the valve part 43 in the relief valve 4 is in the second radial direction, which is different from the first radial direction of the pump body 1. It is the direction. As a result, the discharge valve 8 and the relief valve 4 can be arranged in positions where they do not overlap with each other in the vertical direction, and the space inside the pump body 1 can be effectively utilized, and the size of the pump body 1 can be reduced. .

[Operation of high pressure fuel supply pump]
Next, the operation of the high-pressure fuel supply pump according to this embodiment will be explained using FIGS. 2 and 4.

In FIG. 2, when the plunger 2 is lowered and the electromagnetic intake valve 3 is open, fuel flows into the pressurizing chamber 11 from the intake passage 1d. Hereinafter, the stroke in which the plunger 2 descends will be referred to as a suction stroke. On the other hand, when the plunger 2 rises and the electromagnetic suction valve 3 is closed, the fuel in the pressurizing chamber 11 is pressurized and is forced to pass through the discharge valve 8 to the common rail 106 (see FIG. 1). Ru. Hereinafter, the process in which the plunger 2 rises will be referred to as an upward stroke.

As described above, if the electromagnetic suction valve 3 is closed during the ascent stroke, the fuel sucked into the pressurizing chamber 11 during the suction stroke is pressurized and discharged to the common rail 106 side. On the other hand, if the electromagnetic suction valve 3 is open during the ascending process, the fuel in the pressurizing chamber 11 is pushed back to the suction passage 1d side and is not discharged to the common rail 106 side. In this way, the discharge of fuel by the high-pressure fuel supply pump 100 is controlled by opening and closing the electromagnetic intake valve 3. The opening and closing of the electromagnetic intake valve 3 is controlled by the ECU 101.

In the suction stroke, the volume of the pressurizing chamber 11 increases and the fuel pressure within the pressurizing chamber 11 decreases. This reduces the fluid pressure difference between the suction port 31b and the pressurizing chamber 11 (hereinafter referred to as "the fluid pressure difference before and after the valve portion 32"). When the biasing force of the rod biasing spring 34 becomes larger than the fluid pressure difference across the valve portion 32, the rod 33 moves in the valve opening direction, and the valve portion 32 separates from the seating portion 31a of the suction valve seat 31. , the electromagnetic intake valve 3 becomes open.

When the electromagnetic intake valve 3 is in the open state, the fuel in the intake port 31b passes between the valve part 32 and the seating part 31a, passes through a plurality of fuel passage holes (not shown) in the stopper 37, and enters the pressurizing chamber 11. flows into. When the electromagnetic suction valve 3 is in the open state, the valve portion 32 comes into contact with the stopper 37, so that the position of the valve portion 32 in the valve opening direction is regulated. The gap that exists between the valve portion 32 and the seating portion 31a when the electromagnetic suction valve 3 is in the open state is the movable range of the valve portion 32, and this is the valve opening stroke.

After completing the suction stroke, move on to the upward stroke. At this time, the electromagnetic coil 35 remains in a non-energized state, and no magnetic attraction force is acting between the anchor 36 and the magnetic core 39. The valve portion 32 has a biasing force in the valve opening direction corresponding to the difference between the biasing forces between the rod biasing spring 34 and the valve biasing spring 38, and a backflow of fuel from the pressurizing chamber 11 to the low pressure fuel flow path 10a. The force that presses the valve in the closing direction is exerted by the fluid force generated when the valve is closed.

In this state, in order to maintain the electromagnetic suction valve 3 in the open state, the difference between the biasing forces between the rod biasing spring 34 and the valve biasing spring 38 is set to be larger than the fluid force. The volume of the pressurizing chamber 11 decreases as the plunger 2 rises. Therefore, the fuel that has been sucked into the pressurizing chamber 11 passes between the valve section 32 and the seating section 31a again and is returned to the suction port 31b, causing the pressure inside the pressurizing chamber 11 to rise. There is no. This stroke is called a return stroke.

In the return process, when a control signal from the ECU 101 (see FIG. 1) is applied to the electromagnetic intake valve 3, a current flows through the electromagnetic coil 35 via the terminal member 40. When current flows through the electromagnetic coil 35, a magnetic attraction force acts between the magnetic core 39 and the anchor 36, and the anchor 36 (rod 33) is attracted to the magnetic core 39. As a result, the anchor 36 (rod 33) moves in the valve closing direction (away from the valve portion 32) against the biasing force of the rod biasing spring 34.

When the anchor 36 (rod 33) moves in the valve-closing direction, the valve portion 32 is released from the biasing force in the valve-opening direction, and is freed from the biasing force by the valve biasing spring 38 and the flow caused by the fuel flowing into the suction passage 10b. Moves in the valve closing direction depending on physical strength. Then, when the valve portion 32 contacts the seating portion 31a of the suction valve seat 31 (the valve portion 32 is seated on the seating portion 31a), the electromagnetic suction valve 3 enters the closed state.

After the electromagnetic suction valve 3 is closed, the pressure of the fuel in the pressurizing chamber 11 increases as the plunger 2 rises, and when the pressure reaches a predetermined level or higher, it passes through the discharge valve 8 and flows into the common rail 106 (see FIG. 1). is discharged to. This stroke is called a discharge stroke. That is, the upward stroke of the plunger 2 from the lower starting point to the upper starting point consists of a return stroke and a discharge stroke. By controlling the timing at which the electromagnetic coil 35 of the electromagnetic intake valve 3 is energized, the amount of high-pressure fuel discharged can be controlled.

If the timing of energizing the electromagnetic coil 35 is made earlier, the proportion of the return stroke during the upward stroke becomes smaller and the proportion of the discharge stroke becomes larger. As a result, less fuel is returned to the suction passage 10b, and more fuel is discharged under high pressure. On the other hand, if the timing of energizing the electromagnetic coil 35 is delayed, the proportion of the return stroke during the upward stroke increases, and the proportion of the discharge stroke decreases. As a result, more fuel is returned to the suction passage 10b, and less fuel is discharged under high pressure. In this way, by controlling the timing of energization to the electromagnetic coil 35, the amount of fuel discharged at high pressure can be controlled to the amount required by the engine (internal combustion engine).

[Effect]
As explained above, the high-pressure fuel supply pump (fuel pump) 100 of this embodiment communicates with the plunger 2, the cylinder 6 that guides the reciprocating movement of the plunger 2, and the pressurizing chamber 11, and the cylinder 6 communicates with the pressurizing chamber 11. a pump body 1 provided with a cylinder insertion hole (third chamber 1c) into which the cylinder is inserted; A sealing member 20 is provided, which is arranged in a first annular groove 2r provided on the sliding surface of the plunger 2 and in contact with the sliding surface of the cylinder 6. The first annular groove 2r and the seal member 20 are provided between the pressurizing chamber 11 and the auxiliary chamber 17a, and the cylinder 6 is located closer to the seal member 20 in the axial direction of the plunger 2. The cylinder sliding surface on the sub-chamber 17a side has a communication hole (fuel supply hole 6d) connected to the sub-chamber 17a.

This communication hole (fuel supply hole 6d) makes it possible to supply fuel to the sliding parts of the plunger 2 and cylinder 6 to form a fuel oil film even when high-pressure fuel is cut off by the seal member 20. This makes it possible to prevent the plunger 2 from sticking.

Furthermore, the cylinder sliding surface has a second annular groove 6e connected to the communication hole (fuel supply hole 6d). Further, in the axial direction of the plunger 2, the width of the second annular groove 6e is larger than the width of the communication hole (fuel supply hole 6d).

This second annular groove 6e allows fuel to be supplied to the entire circumferential gap of the plunger 2.

Furthermore, the volume of the subchamber 17a is configured to change due to the reciprocating movement of the plunger 2.

Thereby, low-pressure fuel can be effectively supplied to the communication hole (fuel supply hole 6d) by the flow of fuel due to the volume change in the subchamber 17a.

Further, the plunger 2 has a stepped portion 2c, and the stepped portion 2c is (always) located in the subchamber 17a.

Thereby, the volume change of the subchamber 17a can be promoted by the stepped portion 2c of the plunger 2.

It also has a scraping groove 2d provided on the sliding surface of the plunger 2, and the scraping groove 2d is provided at a position overlapping with the communication hole (fuel supply hole 6d) and the second annular groove 6e. .

The scraping groove 2d allows the fuel accumulated in the communication hole (fuel supply hole 6d) and the second annular groove 6e to be supplied in the axial direction of the plunger 2, thereby making it possible to more effectively prevent the plunger 2 from sticking.

Further, the pump body 1 is provided with a fuel passage 10c that communicates the auxiliary chamber 17a and the low-pressure fuel chamber 10, and the communication hole (fuel supply hole 6d) and the fuel passage 10c are arranged around the axis of the plunger 2 ( provided at the same position in the circumferential direction).

With this arrangement, fuel can be effectively supplied to the communication hole (fuel supply hole 6d) by the fuel flow through the fuel passage 10c.

Further, the cylinder 6 has a separate communication hole (fuel supply hole 6g ). The separate communication hole (fuel supply hole 6g) is connected to the pressurizing chamber 11 through a gap between the cylinder 6 and the cylinder insertion hole (third chamber 1c) of the pump body 1.

This separate communication hole (fuel supply hole 6g) makes it possible to form a stable oil film on the sliding part closer to the pressurizing chamber 11 than the seal member 20, even when fuel lubrication is depleted due to fuel vaporization, etc. It is possible to prevent the plunger 2 from sticking.

Furthermore, the cylinder sliding surface has a third annular groove 6h connected to the separate communication hole (fuel supply hole 6g). Further, in the axial direction of the plunger 2, the width of the third annular groove 6h is larger than the width of the separate communication hole (fuel supply hole 6g).

This third annular groove 6h allows fuel to be supplied to the entire circumferential gap of the plunger 2.

Further, there is a separate scraping groove 2g provided on the sliding surface of the plunger 2, and the separate scraping groove 2g overlaps with the separate communication hole (fuel supply hole 6g) and the third annular groove 6h. located at the location.

The scraping groove 2g allows the fuel accumulated in the separate communication hole (fuel supply hole 6g) and the third annular groove 6h to be supplied in the axial direction of the plunger 2, thereby more effectively preventing the plunger 2 from sticking. can.

That is, the high-pressure fuel supply pump (fuel pump) 100 of the present embodiment described above has a fuel supply hole that guides fuel to a lower pressure side than the seal member 20 where the sliding portion of the cylinder 6 and the plunger 2 tends to be short of fuel supply. is provided in the cylinder 6. Specifically, the cylinder 6 is provided with a fuel supply hole that connects the plunger 2, the sliding portion of the cylinder 6, and the auxiliary chamber 17a.

According to the high-pressure fuel supply pump (fuel pump) 100 of the present embodiment, even if high-pressure fuel is cut off by the seal member 20, it is possible to form a fuel oil film on the sliding part, and the plunger 2 Sticking can be prevented.

The embodiments of the fuel pump of the present invention have been described above, including their effects. However, the fuel pump of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the invention as set forth in the claims. Further, the embodiments described above have been described in detail to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described.

1...Pump body, 1a...First chamber, 1b...Second chamber, 1c...Third chamber (cylinder insertion hole), 1d...Suction passage, 1e...Communication hole, 1f...Tapered surface, 1g...Top surface (stepped part) ), 1A... Center line, 2... Plunger, 2a... Plunger large diameter part, 2b... Plunger small diameter part, 2c... Plunger step part, 2d... Scraping groove, 2g... Scraping groove (separate scraping groove), 2r... Annular groove (first annular groove), 3... Electromagnetic suction valve, 4... Relief valve, 5... Suction joint, 6... Cylinder, 6a... Press-fitting part, 6b... Cylinder inner circumferential part, 6c... Diameter reduction part, 6d... Fuel supply Hole (communicating hole), 6e...Annular groove (second annular groove), 6g...Fuel supply hole (separate communicating hole), 6h...Annular groove (third annular groove), 6i...Top surface, 6j...Communication Groove, 8...Discharge valve, 9...Pressure pulsation reduction mechanism, 10...Low pressure fuel chamber, 11...Pressure chamber, 12...Discharge joint, 17a...Subchamber, 20...Seal member, 31...Suction valve seat, 31a...Seating part, 31b... Suction port, 32... Valve part, 33... Rod, 35... Electromagnetic coil, 36... Anchor, 37... Stopper, 39... Magnetic core, 40... Terminal member, 42... Relief valve holder, 43... Valve part, 44... Seat member, 81... Discharge valve seat, 82... Valve section, 84... Discharge valve stopper, 85... Plug, 100... High pressure fuel supply pump (fuel pump), 101... ECU, 102... Feed pump, 103... Fuel tank , 104...Low pressure piping, 105...Fuel pressure sensor, 106...Common rail, 107...Injector

Claims

A plunger and
a cylinder that guides the reciprocating movement of the plunger;
a pump body communicating with a pressurizing chamber and provided with a cylinder insertion hole into which the cylinder is inserted;
an auxiliary chamber provided at a position opposite to the pressurizing chamber of the plunger and containing low-pressure fuel;
a sealing member disposed in a first annular groove provided on the sliding surface of the plunger and in contact with the sliding surface of the cylinder,
The first annular groove and the sealing member are provided between the pressurizing chamber and the subchamber,
The cylinder is a fuel pump, wherein the cylinder has a communication hole connected to the sub-chamber on a cylinder sliding surface closer to the sub-chamber than the seal member in the axial direction of the plunger.
The fuel pump according to claim 1,
The fuel pump has a second annular groove connected to the communication hole on the cylinder sliding surface.
The fuel pump according to claim 1,
The fuel pump is configured such that the volume of the subchamber changes due to reciprocating motion of the plunger.
The fuel pump according to claim 3,
The plunger has a stepped portion, and the stepped portion is located in the subchamber.
The fuel pump according to claim 1,
The fuel pump has a scraping groove provided on a sliding surface of the plunger, and the scraping groove is provided at a position overlapping with the communication hole.
The fuel pump according to claim 2,
A fuel pump comprising a scraping groove provided on a sliding surface of the plunger, the scraping groove being provided at a position overlapping with the second annular groove.
The fuel pump according to claim 1,
The pump body is provided with a fuel passage communicating the sub-chamber and the low-pressure fuel chamber,
A fuel pump, wherein the communication hole and the fuel passage are provided at the same position around the axis of the plunger.
The fuel pump according to claim 2,
A fuel pump, wherein the width of the second annular groove is greater than the width of the communication hole in the axial direction of the plunger.
The fuel pump according to claim 1,
In the fuel pump, the cylinder has a separate communication hole connected to the pressurizing chamber on a cylinder sliding surface closer to the pressurizing chamber than the sealing member in the axial direction of the plunger.
The fuel pump according to claim 9,
In the fuel pump, the separate communication hole is connected to the pressurizing chamber through a gap between the cylinder and the cylinder insertion hole of the pump body.
The fuel pump according to claim 9,
The fuel pump has a third annular groove connected to the separate communication hole on the cylinder sliding surface.
The fuel pump according to claim 9,
The fuel pump has a separate scraping groove provided on the sliding surface of the plunger, and the separate scraping groove is provided at a position overlapping with the separate communication hole.
The fuel pump according to claim 11,
The fuel pump has a separate scraping groove provided on the sliding surface of the plunger, and the separate scraping groove is provided at a position overlapping with the third annular groove.
The fuel pump according to claim 11,
In the fuel pump, the width of the third annular groove is larger than the width of the separate communication hole in the axial direction of the plunger.
A plunger and
a cylinder that guides the reciprocating movement of the plunger;
a pump body communicating with a pressurizing chamber and provided with a cylinder insertion hole into which the cylinder is inserted;
an auxiliary chamber provided at a position opposite to the pressurizing chamber of the plunger and containing low-pressure fuel;
a sealing member that seals a sliding surface gap between the plunger and the cylinder;
The sealing member is provided between the pressurizing chamber and the sub-chamber,
The cylinder is a fuel pump, wherein the cylinder has a communication hole connected to the sub-chamber on a cylinder sliding surface closer to the sub-chamber than the seal member in the axial direction of the plunger.