High-pressure fuel pump

Abstract

High pressure fuel pump, comprising: a piston (2) comprising a large diameter portion (2a) and a small diameter portion (2b); a pressurizing chamber (11) whose volume is increased or decreased by a reciprocating movement of the piston (2); a sealing portion (13) disposed on an outer peripheral side of the small diameter portion (2b) of the piston (2) and providing a seal between an upper space (7a) of the small diameter portion (2b) of the piston (2) and an outer space; and a regulating element (16) arranged between the sealing portion (13) and a lower surface (2c) of the large-diameter portion (2a) and regulating the movement of the large-diameter portion (2a) to a side opposite the pressurizing chamber (11), wherein the regulating element (16) comprises an end surface (16c) facing the lower surface (2c) of the large-diameter portion (2a), a gap portion (16e) is formed between an innermost peripheral portion of the end surface (16c) and the small-diameter portion (2b), and further, in addition to the gap portion (16e), a communication path (16d) is formed connecting an upper space (7a) of the end surface (16c) and a lower space (7b), characterized in that an inlet valve (30) which opens and closes a flow path is provided on an upstream side of the pressurizing chamber (11), and the upper space (7a) of the end face (16c) is communicated with a low-pressure space on an upstream side of the inlet valve (30), and the fuel moves back and forth between the low-pressure chamber and the upper chamber of the end face (16c) together with the reciprocating movement of the piston (2).

Description

Technical area

[0001] The present invention relates to a high-pressure fuel pump according to claim 1, in particular a high-pressure fuel pump provided with a sealing portion protecting member. Technical background

[0002] Technical background in this technical field is, for example, Patent Literature 1 (JP 2016-118211 A). In Patent Literature 1, there is a disclosure that "a seal portion 13 at the lower end of a spring retainer 7 is held by a seal retainer 15 and a spring retainer 7, which are press-fitted and fixed to a cylindrical inner peripheral surface 7c of a spring retainer 7. The center axis of the seal portion 13 is held coaxially with the center axis of the cylindrical inner peripheral surface 7c of the spring retainer 7, and at the same time, the center axis of a cylindrical fitting portion 7e is also held coaxially. The piston 2 and the seal portion 13 are slidably mounted on the lower end of the cylinder 6.

[0003] The sealing portion 13 prevents the fuel in a sealing chamber 10f from flowing into an engine on the side of a tappet 3. At the same time, lubricating oil (including engine oil) lubricating a sliding portion in an engine room is prevented from flowing into a pump main body 1. (See paragraphs 0078 and 0079). Furthermore, JP 2015-055231 A (cf. PTL 2) also discloses a high-pressure fuel pump, wherein a piston stopper is provided, which is screwed onto an external thread of a cylinder-forming part and fixed to the cylinder-forming part. The piston stopper has an inlet opening 381 and an outlet opening 191, which ensure fuel circulation around the piston. DE 10 2006 055 298 A1 (cf. PTL 3) discloses a sealing arrangement for sealing a piston of a high-pressure pump, having a passage opening 146 that connects a sealing chamber to a first media chamber and thereby enables fuel circulation. Literature listPatent literature PTL 1: JP 2016-118211 A PTL 2: JP 2015-055231 A PTL 3: DE 10 2006 055 298 A1 Summary of the inventionTechnical problem

[0004] In Patent Literature 1, before the high-pressure fuel pump is mounted on the engine, the piston 2 is urged toward the seal portion 13 by the spring 4. To prevent the piston 2 from contacting the seal portion 13 and being damaged, the seal retainer 15 is provided with a seal portion protection function (stop), so that the piston 2 does not directly contact the seal portion 13 and is not damaged.

[0005] However, if this regulating portion is provided, the gap between the small-diameter piston portion 2b and the seal portion protecting (stopper) portion of the seal retainer 15 is small, and fuel circulation around the seal portion 13 is deteriorated. Therefore, there is a possibility that the heat generated by friction between the small-diameter piston portion 2b and the seal portion 13 is not sufficiently dissipated (the seal portion is not cooled), and the resin portion of the seal portion 13 exceeds the allowable temperature of the seal portion 13 and melts.

[0006] An object of the present invention is to provide a high-pressure fuel pump in which the cooling performance of a seal portion is improved by fuel circulation while protecting the seal portion without complicating the component shape. Solution to the problem

[0007] The problem is solved by the features of claim 1. Particular embodiments are described in the dependent claims. Advantageous effects of the invention

[0008] According to the present invention, it becomes possible to provide a high-pressure fuel pump in which the cooling performance of the seal portion is improved by fuel circulation while protecting the seal portion without complicating the component shape. Other configurations, operations, and effects of the present invention are described in detail in the following examples. Short description of the drawings [ Fig. 1] Fig. 1 shows a configuration diagram of an engine system in which a high-pressure fuel pump of the present embodiment is applied. [ Fig. 2] Fig. 2 is a longitudinal sectional view of the high pressure fuel pump of one embodiment of the present embodiment. [ Fig. 3] Fig. 3 is a horizontal sectional view of the high pressure fuel pump of the embodiment of the present embodiment seen from above. [ Fig. 4] Fig. 4 is a longitudinal sectional view of the high pressure fuel pump of the embodiment of the present embodiment from a direction other than Fig. 1. [ Fig. 5] Fig. 5 is a plan view of a regulating member 16 of the first embodiment. [ Fig. 6] Fig. 6 is a diagram illustrating the relationship between a piston 2 and the regulating member 16 before the high-pressure fuel pump is mounted on the engine in the first embodiment. [ Fig. 7] Fig. 7 is a diagram illustrating the relationship between the piston 2 and the regulating member 16 after the high-pressure fuel pump is mounted on the engine in the first embodiment. [ Fig. 8] Fig. 8 is a diagram illustrating the relationship between the piston 2 and the regulating member 16 before the high-pressure fuel pump is mounted on the engine in the second embodiment. [ Fig. 9] Fig. 9 is a diagram illustrating the relationship between the piston 2 and the regulating member 16 after the high-pressure fuel pump is mounted on the engine in the second embodiment. [ Fig. 10] Fig. 10 is a plan view of a regulating member 16 of the third embodiment. Description of embodiments

[0009] The embodiments of the present invention will be described below. First embodiment

[0010] Fig. Figure 1 shows an overall configuration diagram of the engine system. A portion surrounded by a dashed line indicates a main body of the high-pressure fuel pump (hereinafter referred to as a high-pressure fuel pump), and mechanisms / components shown on the inside of the dashed line are indicated as being integrated into a pump body 1. Fig. 1 is a schematic drawing showing the operation of the engine system, and the detailed configuration can be derived from the configuration of a high-pressure fuel pump as shown in Fig. 2 and the following drawings. Fig. 2 is a longitudinal sectional view of the high pressure fuel pump of the present embodiment and Fig. 3 is a horizontal sectional view of the high-pressure fuel pump as seen from above. Fig. 4 a longitudinal sectional view of the high pressure fuel pump from a different direction than Fig. 2.

[0011] The fuel in a fuel tank 20 is pumped up by a feed pump 21 based on a signal from an engine control unit 27 (hereinafter: ECU). This fuel is pressurized until it reaches a corresponding feed pressure and is fed through a suction pipe 28 to a low-pressure fuel inlet port 10a of the high-pressure fuel pump.

[0012] The fuel that has passed through an intake manifold 51 from the low-pressure fuel inlet port 10a passes through damper chambers 10b, 10c (see Fig. 4), in which a pressure pulsation reducing mechanism 9 is provided to reach a suction port 31b of the solenoid valve mechanism 300, which is a variable capacity mechanism. Specifically, the solenoid valve mechanism 300 is a solenoid intake valve mechanism.

[0013] The fuel that has flowed into the solenoid valve mechanism 300 passes through an inlet port opened and closed by the inlet valve 30 and flows into a pressurizing chamber 11. The force of the reciprocating movement is applied to a piston 2 by a cam 93 of an engine (see Fig. 4). Due to the reciprocating motion of the piston 2, fuel is sucked from the intake valve 30 during a downward stroke of the piston 2, and the fuel is pressurized during an upward stroke. The pressurized fuel is pumped via an exhaust valve mechanism 8 to a common rail 23, on which a pressure sensor 26 is mounted. Based on a signal from the ECU 27, an injector 24 injects fuel into the engine. The present embodiment is a high-pressure fuel pump applied to a so-called direct-injection engine system, in which the injector 24 injects fuel directly into a cylinder bore of the engine. The high-pressure fuel pump delivers fuel at a flow rate of the desired fuel supply in response to a signal from the ECU 27 to the solenoid valve mechanism 300.

[0014] As in Fig. 2 and Fig. 3, the high-pressure fuel pump of the present embodiment is mounted in close contact with a high-pressure fuel pump mounting portion 90 of the internal combustion engine. In particular, as shown in Fig. 3, screw holes 1b are formed in a mounting flange 1a provided in the pump body 1, and a plurality of screws (not shown) are inserted therein. This brings the mounting flange 1a into close contact with the high-pressure fuel pump mounting portion 90 of the internal combustion engine and fixes it thereto. An O-ring 61 is installed in the pump body 1 for sealing between the high-pressure fuel pump mounting portion 90 and the pump body 1 to prevent engine oil from leaking to the outside.

[0015] As in Fig. 2 and Fig. As shown in Figure 4, a cylinder 6 is attached to the pump body 1, which guides the reciprocating movement of the piston 2 and, together with the pump body 1, forms the pressurizing chamber 11. That is, the piston 2 reciprocates within the cylinder to change the volume of the pressurizing chamber. The solenoid valve mechanism 300 for supplying fuel to the pressurizing chamber 11 and the exhaust valve mechanism 8 for discharging fuel from the pressurizing chamber 11 into the exhaust passage are provided.

[0016] The cylinder 6 is press-fitted with the pump body 1 on the outer peripheral side thereof. The pump body 1 is formed with an insertion hole for inserting the cylinder 6 from below, and a convex inner peripheral portion is formed to be deformed toward the inner peripheral side so that it comes into contact with the lower surface of a fixed portion 6a of the cylinder 6 at the lower end of the insertion hole. The upper surface of the convex inner peripheral portion of the pump body 1 presses the fixed portion 6a of the cylinder 6 upward in the drawing, and the fuel pressurized in the pressurization chamber 11 on the upper end surface of the cylinder 6 is sealed so as not to leak to the low-pressure side.

[0017] At the lower end of piston 2, a tappet 92 is provided, which converts the rotational movement of the cam 93, which is attached to a camshaft of the internal combustion engine, into a vertical movement and transmits it to piston 2. Tappet 92 is pressure-connected to tappet 92 via a spring 4 and a holder 15. This allows piston 2 to move up and down along with the rotational movement of cam 93.

[0018] A piston seal 13, held at the lower end of the inner periphery of the seal holder 7, is installed in slidable contact with the outer periphery of the piston 2 at the lower part of the cylinder 6 in the figure. This seals the fuel in an upper space 7a when the piston 2 slides, preventing the fuel from flowing into the internal combustion engine. At the same time, lubricating oil (including engine oil) that lubricates the sliding portion in the internal combustion engine from flowing into the pump body 1.

[0019] A regulating member 16 is attached to the upper part of the piston seal 13 to prevent the piston 2 from falling when the high-pressure fuel pump is not attached to the engine. The regulating member 16 is formed of a metal member and is press-fitted and fixed to the seal holder 7. When the high-pressure fuel pump is not attached to the engine, the piston 2 moves downward by gravity, but the piston 2 is prevented from falling by the outer peripheral portion of a large-diameter portion 2a that comes into contact with the lower surface of the regulating member 16.

[0020] As in Fig. 3 and Fig. As shown in Figure 4, the intake port 51 is attached to the side surface of the pump body 1 of the high-pressure fuel pump. The intake port 51 is connected to the low-pressure line that supplies fuel from the vehicle's fuel tank 20, and from there, the fuel is supplied to the interior of the high-pressure fuel pump. A suction filter 52 serves to prevent foreign matter present between the fuel tank 20 and the low-pressure fuel inlet port 10a from entering the high-pressure fuel pump through the fuel flow.

[0021] The fuel that has passed through the low-pressure fuel inlet port 10a passes through a low-pressure fuel intake passage connected to the Fig. 4, to the pressure pulsation reducing mechanism 9. The pressure pulsation reducing mechanism 9 is disposed in the damper chambers (10b, 10c) between a damper cover 14 and the upper end surface of the pump body 1, and is supported from below by a support member 9a disposed on the upper end surface of the pump body 1. Specifically, the pressure pulsation reducing mechanism 9 is a metal damper configured by superposing two metal diaphragms. A gas of 0.3 MPa to 0.6 MPa is sealed inside the pressure pulsation reducing mechanism 9, and the outer peripheral edge is fixed thereto by welding.

[0022] The upper and lower surfaces of the pressure pulsation reduction mechanism 9 are formed with the low-pressure fuel inlet port 10a and the damper chambers (10b, 10c) connected to the low-pressure fuel intake passage. Although not shown in the figure, the retaining member 9a is formed with a passage connecting the upper and lower surfaces of the pressure pulsation reduction mechanism 9.

[0023] The fuel that has passed through the damper chambers (10b, 10c) then enters the intake port 31b of the solenoid valve mechanism 300 via a low-pressure fuel intake passage 10d formed vertically in communication with the pump body. The intake port 31b is formed to communicate with an intake valve seat member 31 and form an intake valve seat 31a in the vertical direction. A terminal 46 is integrally formed with the connector, and the other end can be connected to the engine control unit side.

[0024] The solenoid valve mechanism 300 is described with reference to Fig. 2 and Fig. 3. When the piston 2 moves toward the cam 93 due to the rotation of the cam 93 and is in the intake stroke state, the volume of the pressurizing chamber 11 increases, and the fuel pressure in the pressurizing chamber 11 decreases. In this process, when the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the suction port 31b, the intake valve 30 is opened. When the intake valve 30 reaches the maximum lift state, the intake valve 30 comes into contact with a stopper 32. When the intake valve 30 is lifted, the opening formed in the intake valve seat member 31 is opened, and the valve is opened. The fuel flows through the opening of the intake valve seat member 31 and flows into the pressurizing chamber 11 through a hole formed in the pump body 1 in the transverse direction.

[0025] After the piston 2 completes the intake stroke, the piston 2 begins to move upward and moves to the upward stroke. At this time, an electromagnetic coil 43 remains in a de-energized state, and no magnetic biasing force acts. A rod biasing spring 40 biases a rod projection 35a convex to the outer diameter side of a rod 35 and is adjusted to have a biasing force necessary and sufficient to keep the intake valve 30 open in a de-energized state. The volume of the pressurizing chamber 11 decreases with the upward movement of the piston 2. In this state, the fuel sucked into the pressurizing chamber 11 is returned to the low-pressure fuel intake passage 10d through the orifice of the intake valve 30 in the valve-open state, so that the pressure in the pressurizing chamber does not increase.This stroke is called a return stroke.

[0026] In this state, when a control signal from the ECU 27 is applied to the solenoid valve mechanism 300, a current flows through the electromagnetic coil 43 via the terminal 46. A magnetic attraction force acts between a magnetic core 39 and an armature 36, and the magnetic core 39 and the armature 36 come into contact with each other at the magnetic attraction surface. The magnetic attraction force overcomes the biasing force of the rod biasing spring 40 and presses the armature 36. The armature 36 engages the rod projection 35a and moves the rod 35 away from the intake valve 30.

[0027] At this time, the intake valve 30 is closed by the biasing force of the intake valve biasing spring 33 and the fluid force caused by the fuel flowing into the intake passage 10d. After the valve is closed, the fuel pressure in the pressurizing chamber 11 increases with the upward movement of the piston 2, and when the fuel pressure becomes equal to or greater than the pressure in a fuel outlet port 12, high-pressure fuel is discharged through the exhaust valve mechanism 8 and supplied to the common rail 23. This stroke is called an exhaust stroke.

[0028] That is, the upward stroke from the lower starting point to the upper starting point of the piston 2 includes a return stroke and an exhaust stroke. Subsequently, by controlling the energization timing of the coil 43 of the solenoid valve mechanism 300, the amount of high-pressure fuel discharged can be controlled.

[0029] The piston 2 comprises a large-diameter section 2a and a small-diameter section 2b, and the volume of the upper chamber 7a increases or decreases with the reciprocating movement of the piston. The upper chamber 7a communicates with the damping chambers (10b, 10c) via a fuel passage 10e. When the piston 2 is lowered, fuel flows from the upper chamber 7a to the damping chambers (10b, 10c), and when it is raised, fuel flows from the damping chambers (10b, 10c) to the upper chamber 7a.

[0030] This provides such a function that the fuel flow rate into and out of the pump during the suction stroke or the return stroke of the pump can be reduced and the pressure pulsation generated within the high pressure fuel pump is reduced.

[0031] As in Fig. As shown in Fig. 3, the discharge valve mechanism 8 provided at the outlet of the pressurizing chamber 11 includes a discharge valve seat 8a, a discharge valve 8b that contacts and separates from the discharge valve seat 8a, a discharge valve spring 8c that biases the discharge valve 8b toward the discharge valve seat 8a, and a discharge valve stopper 8d that determines the stroke (moving distance) of the discharge valve 8b. The discharge valve stopper 8d and the pump body 1 are joined by welding at an abutment portion 8e for separating the fuel from the outside.

[0032] In a state where there is no fuel pressure differential between the pressurizing chamber 11 and an exhaust valve chamber 12a, the exhaust valve 8b is pressure-connected to the exhaust valve seat 8a by the biasing force of the exhaust valve spring 8c and is in a closed state. When the fuel pressure in the pressurizing chamber 11 becomes higher than the fuel pressure in the exhaust valve chamber 12a, the exhaust valve 8b opens against the exhaust valve spring 8c. The high-pressure fuel in the pressurizing chamber 11 is discharged to the common rail 23 via the exhaust valve chamber 12a, a fuel discharge passage 12b, and the fuel discharge port 12. When the exhaust valve 8b opens, it comes into contact with the exhaust valve stopper 8d, and the stroke is limited. Thus, the stroke of the exhaust valve 8b is appropriately determined by the exhaust valve stopper 8d.This prevents a situation in which the fuel discharged into the discharge valve chamber 12a at high pressure flows back into the pressurizing chamber 11 due to the delay in closing the discharge valve 8b caused by the excessively large lift, so that a reduction in the efficiency of the high-pressure fuel pump can be suppressed.

[0033] When the fuel in the pressurizing chamber 11 is pressurized and the discharge valve 8b is opened, the high-pressure fuel in the pressurizing chamber 11 passes through the fuel discharge passage 12b and is discharged from the fuel discharge port 12. The fuel discharge port 12 is formed in a discharge port 60, and the discharge port 60 is welded and connected to the pump body 1 by a welding portion to ensure fuel passage.

[0034] Next, a Fig. 2 and Fig. 3 described pressure relief valve mechanism 200.

[0035] The relief valve mechanism 200 includes a relief body 201, a relief valve 202, a relief valve retainer 203, a relief spring 204, and a spring stop 205. The relief body 201 is provided with a tapered seat portion. The valve 202 is loaded with the load of the relief spring 204 via the valve retainer 203 and pressed against the seat portion of the relief body 201 to block the fuel in cooperation with the seat portion.

[0036] When the pressure of the fuel outlet port 12 becomes abnormally high due to a failure of the solenoid inlet valve 300 of the high-pressure fuel pump and exceeds the set pressure of the relief valve 200, the abnormally high-pressure fuel is discharged into the damping chamber 10c on the low-pressure side via a relief passage 213. In this embodiment, the discharge destination of the relief valve mechanism 200 is the damping chamber 10c, but it may also be the pressurizing chamber 11.

[0037] Next, the configuration around the seal portion 13 (piston seal) of the present embodiment will be described with reference to Fig. 5, Fig. 6 and Fig. 7 described. Fig. 5 is a plan view of the regulating element 16.

[0038] Fig. Figure 6 is a view showing the relationship between the piston 2 and the regulating member 16 before the high-pressure fuel pump is mounted on the engine. Before the high-pressure fuel pump is mounted on the engine, the piston 2 moves in the direction of the arrow by the biasing force of the spring 4. Fig. 4 downward, but a lower surface 2c of the large diameter portion 2a of the piston 2 is supported on an end surface 16c of the regulating member 16 which is in contact therewith.

[0039] Fig. Fig. 7 is a view showing the relationship between the piston 2 and the regulating element 16 after the high-pressure fuel pump is mounted on the engine. Since in this case the spring 4 is Fig. 4, the piston 2 is biased upward by the spring 4 through the retainer 15. Thus, after being attached to the engine, the piston 2 is driven in the vertical direction without coming into contact with the end face 16c of the regulating element 16.

[0040] The sealing portion 13 prevents the fuel in the high-pressure fuel pump from flowing into the engine or the oil in the engine from flowing into the high-pressure fuel pump. The sealing portion 13 includes a spring 13a whose upper and lower parts extend in the radial direction. Thus, the sealing portion 13 is held between the piston 2 and the seal holder 7 with the compressive force generated by the spring 13a in the radial direction. Further, in the sealing portion 13, a depressed portion 13b, which is depressed from the end surface (upper surface) facing a lower space 7b to the opposite side (bottom side) of the lower space 7b, is formed in the entire circumferential direction on the radially outer side of the small-diameter portion 2b.

[0041] A frictional force is also generated between the seal portion 13 and the small diameter portion 2b of the piston 2 by a radially urging force generated by the spring 13a. When the engine is started and the high-pressure fuel pump is in a running state, the average pressure from the feed pump 21 is applied to the seal portion 13, and the seal portion 13 is Fig. 7 is pressed downward. Even if a frictional force is generated between the seal portion 13 and the small diameter portion 2b of the piston 2, the seal portion 13 can be pressed against the lower surface of the seal holder 7.

[0042] Before the high pressure fuel pump is attached to the engine head, the piston 2 is Fig. 6 or Fig. 7 is pressed downward by the spring 4. At this time, there is a possibility that the lower surface 2c of the large-diameter portion 2a of the piston 2 comes into direct contact with the seal portion 13 and damages the seal portion 13. On the other hand, the regulating member 16 is provided as a protection member for the seal portion 13. At this time, the lower surface 2c of the large-diameter portion 2a of the piston 2 is in contact with the lower surface 16c of the regulating member 16, and the piston 2 is further regulated so that it otherwise moves by the seal portion 13. For this reason, the seal portion 13 can be protected. In the present embodiment, the lower surface 2c connecting the large-diameter portion 2a and the small-diameter portion 2b is formed by a plane perpendicular to the direction of the piston axis.According to this configuration, the contact surface with the end face 16c (regulating portion) can be sufficiently ensured with a flat surface, thereby improving reliability. Accordingly, it is possible to more easily achieve both the protective function of the sealing portion 13 before mounting the high-pressure fuel pump on the engine and the cooling function during driving.

[0043] The regulating element 16 is preferably made of a metal element and manufactured by compression molding. This enables cost-effective mass production.

[0044] The underside of the seal portion 13 (outside of the pump) is exposed to oil. Since the seal portion 13 is made of resin material, changes in fuel temperature and oil temperature affect the decrease in the strength of the seal portion 13. Furthermore, the temperature of the seal portion 13 also rises due to sliding heat generated by the up-and-down sliding of the piston 2. Basically, the strength decreases as the temperature of the seal portion 13 increases. Thus, it is necessary to provide a space for the circulation of a fuel having a temperature lower than that of the oil between the regulating member 16 and the seal portion 13 above the seal portion 13 exposed to the fuel (inside the pump). The length of this space in the piston axis direction is preferably greater than, for example, the metal thickness of the regulating member 16. This allows the seal portion 13 to be cooled by the fuel.It is important to reliably ensure a space between the regulating element 16 and the sealing section 13 and to cool the sealing section 13.

[0045] As described above, the high-pressure fuel pump of the present embodiment includes the plunger 2 having the large-diameter portion 2a and the small-diameter portion 2b, the pressurizing chamber 11 whose volume is increased or decreased by the reciprocating movement of the plunger 2, and the sealing portion (piston seal 13) disposed on the outer peripheral side of the small-diameter portion 2b of the plunger 2 and sealing between the outer peripheral side space (upper space 7a) of the small-diameter portion 2b of the plunger 2 and the outer space (engine side space). The regulating member 16 is disposed between the sealing portion 13 and the lower surface 2c of the large-diameter portion 2a of the plunger 2 and regulates the movement of the large-diameter portion 2a of the plunger 2 to the side opposite the pressurizing chamber 11.The regulating element 16 includes the end surface 16c facing the lower surface 2c of the large-diameter portion 2a, and a gap portion 16e is formed between the innermost peripheral portion of the end surface 16c and the small-diameter portion 2b. In addition to the gap portion 16e, a communication path 16d is formed that connects the upper space 7a of the end surface 16c to the lower space 7b.

[0046] This improves the fuel circulation around the seal portion 13, dissipates the heat generated by friction between the small-diameter portion 2b of the piston 2 and the seal portion 13, and sufficiently cools the seal portion 13. Thus, a high-pressure fuel pump that does not exceed the allowable temperature can be achieved.

[0047] Specifically, the communication path 16d is formed by a notch recessed radially outward from the innermost peripheral portion of the regulating member 16 (inner peripheral portion of the gap portion 16e). Further, the communication path 16d is preferably formed at a position overlapping the connecting portion (lower surface 2c) between the large-diameter portion 2a and the small-diameter portion 2b as viewed from the piston axis direction. Since the fuel moves up and down through the connecting portion (lower surface 2c), the communication path 16d is formed to overlap it. The amount of fuel reciprocating between the upper space 7a and the lower space 7b can thus be increased, and the cooling effect of the seal portion 13 can be further improved.The regulating member 16 includes an inclined portion 16a inclined at the intermediate portion and in contact with the inclined portion of the seal holder 7 to be regulated and held in the axial direction. The communication path 16d is preferably formed such that the length from the innermost peripheral portion (inner peripheral portion of the gap portion 16e) to the outermost peripheral portion of the communication path 16d is greater than the length between the small-diameter portion 2b and the innermost peripheral portion (inner peripheral portion of the gap portion 16e).

[0048] In the piston axis direction, the outermost peripheral portion of the communication path 16d is formed to overlap the recessed portion 13b recessed toward the side opposite the upper space 7a of the seal portion 13. At this time, even when the lower space 7b of the regulating member 16 is small, the fuel enters the recessed portion 13b, so that the cooling performance of the seal portion 13 can be improved.

[0049] A plurality of connecting paths 16d are preferably formed at equal intervals in the circumferential direction, as viewed from the direction of the piston axis. This makes it possible to provide the fuel flow necessary for cooling. As shown in Fig. 2 and Fig. 3, the intake valve 30, which opens and closes the flow path, is provided on the upstream side of the pressurizing chamber 11, and the upper space 7a of the end surface 16c communicates with a low-pressure space (damper chamber 10c) on the upstream side of the intake valve 30. Then, the fuel reciprocates between the low-pressure space and the upper space 7a of the end surface 16c along with the reciprocating movement of the piston 2.

[0050] The regulating member 16 is made of a cylindrical metal member, and the end surface 16c is formed of a bottom surface positioned to face the bottom surface 2c of the large-diameter portion 2a of the piston 2. Furthermore, the seal retainer 7 holds the seal portion 13 and forms an outer peripheral side space 7a of the small-diameter portion 2b. The seal retainer 7 is fixed to the pump body 1, which forms the pressurizing chamber 11, and is configured to support the regulating member 16 in the axial direction of the piston on the inner peripheral side.

[0051] As described above, it is important to sufficiently ensure the communication path 16d between the piston seal 13 and the regulating member 16. This is because the fuel present around the piston seal 13 passes through the communication path 16d and enters and exits, so the cooling effect of the seal portion 13 by the fuel can be expected.

[0052] The problem to be solved in the present embodiment becomes particularly significant when the diameter difference between the large-diameter portion 2a and the small-diameter portion 2b of the piston is small. This is because the inner diameter of the regulating portion of the seal retainer 7 must be smaller than the large-diameter piston portion 2a and larger than the small-diameter portion 2b, and thus the gap between the small-diameter piston portion 2b and the portion of the seal retainer 7 with the seal portion protection function (stopper) is structurally reduced.

[0053] Thus, the above-described effect is particularly effective when a large diameter difference can be ensured between the large diameter portion 2a and the small diameter portion 2b of the piston 2. For example, when the diameter of the large diameter portion 2a is 10 mm and the diameter of the small diameter portion 2b of the piston is 6 mm, the diameter difference is 4 mm, and 2 mm can be ensured as the height of the lower surface 2c. When a clearance of 1 mm is ensured between the sealing portion 13 and the regulating member 16, the cooling effect of the sealing portion is sufficient, and the area of ​​the stopper (end surface 16c) can be sufficiently ensured.

[0054] On the other hand, when the diameter difference between the large diameter portion 2a and the small diameter portion 2b of the piston 2 is small, the situation is different. For example, if the diameter of the large diameter portion 2a of the piston is 8 mm and the diameter of the small diameter portion 2b is 6 mm, the diameter difference is 2 mm. In this case, the height of the bottom surface 2c is 1 mm. The clearance between the sealing portion 13 and the regulating member 16 must be set to a median value of about 0.5 mm, taking tolerances and the like into account. Then there is the problem that the cooling function of the aforementioned sealing portion is insufficient, and the sealing portion 13 is insufficient at high temperature and strength, resulting in damage.

[0055] Thus, in this embodiment, as described above, a structure is provided in which the gap portion 16e is provided on the end surface 16c (regulating portion) of the regulating member 16. By adopting such a structure, the gap portion 16e plays the same role as the clearance between the sealing portion 13 and the regulating member 16, the cooling effect of the sealing portion 13 is sufficiently ensured, and the end surface 16c (regulating portion) can also be provided. Furthermore, since the structure is simple, the regulating member 16 can be manufactured by compression molding and mass-produced at low cost. Second embodiment

[0056] Fig. 8 and Fig. 9 show the second embodiment of the present invention.

[0057] Fig. Fig. 8 is a diagram showing the relationship between the piston 2 and the regulating element 16 before the high pressure fuel pump is mounted on the engine.

[0058] Fig. 9 is a view showing the relationship between the piston 2 and the regulating member 16 after the high-pressure fuel pump is mounted on the engine.

[0059] In the first embodiment, the bottom surface 2c connecting the large-diameter portion 2a and the small-diameter portion 2b is formed by a plane perpendicular to the piston axis direction, but in this embodiment, it is formed by an inclined surface (tapered surface) inclined with respect to the piston axis direction. Since the other configurations are the same as those of the first embodiment, their detailed description is omitted. The regulating member 16 and the seal retainer 7 can be press-formed as in the first embodiment. Third embodiment

[0060] Fig.10 shows a regulating member 16 according to the third embodiment of the present invention. Since the part of the regulating member 16 is the same as in the first or second embodiment, its description is omitted. In this embodiment, a plurality of communication holes 16f are provided. The communication holes 16f do not communicate with the gap portion 16e. Before assembling the motor of the high-pressure fuel pump, the restricting portion 16c comes into contact with the lower surface 2c of the plunger 2 and is protected without coming into contact with the seal portion 13. That is, the communication holes 16f are configured by communication holes formed at positions on the radially outer side with respect to the innermost peripheral portion of the regulating member 16 (inner peripheral portion of the gap portion 16e).

[0061] This allows the fuel to move up and down along the regulating portions 16c through the connecting holes 16f when the engine is mounted and actually driven, so that the sealing portion 13 can be cooled by the fuel. Consequently, it is possible to achieve a high-pressure fuel pump in which the sealing portion 13 is not damaged by high temperatures. List of reference symbols 1 pump body 2 pistons 2a Large diameter section 2b Small diameter section 2c lower surface 4 preload spring 7a upper room 7b lower room 13 Piston seal 16 Regulatory element 16a inclined section 16c frontal surface 16d connecting path 16e gap section

Claims

[1] High pressure fuel pump, comprising: a piston (2) comprising a large diameter portion (2a) and a small diameter portion (2b); a pressurizing chamber (11) whose volume is increased or decreased by a reciprocating movement of the piston (2); a sealing portion (13) disposed on an outer peripheral side of the small diameter portion (2b) of the piston (2) and providing a seal between an upper space (7a) of the small diameter portion (2b) of the piston (2) and an outer space; and a regulating element (16) arranged between the sealing portion (13) and a lower surface (2c) of the large-diameter portion (2a) and regulating the movement of the large-diameter portion (2a) to a side opposite the pressurizing chamber (11), wherein the regulating element (16) comprises an end surface (16c) facing the lower surface (2c) of the large-diameter portion (2a), a gap portion (16e) is formed between an innermost peripheral portion of the end surface (16c) and the small-diameter portion (2b), and further, in addition to the gap portion (16e), a communication path (16d) is formed connecting an upper space (7a) of the end surface (16c) and a lower space (7b), characterized by that an inlet valve (30) which opens and closes a flow path is provided on an upstream side of the pressurizing chamber (11), and the upper space (7a) of the end face (16c) is connected to a low-pressure space on an upstream side of the inlet valve (30), and the fuel moves back and forth between the low-pressure chamber and the upper chamber of the end face (16c) together with the reciprocating movement of the piston (2). [2] A high-pressure fuel pump according to claim 1, wherein the communication path (16d) is formed by a notch formed to be recessed radially outward from the innermost peripheral portion of the end face (16c). [3] A high-pressure fuel pump according to claim 1, wherein the communication path (16d) is formed by a communication hole (16f) formed at a position on a radially outer side with respect to the innermost peripheral portion of the end face (16c). [4] A high-pressure fuel pump according to any one of claims 1 to 3, wherein the communication path (16d) is formed at a position overlapping a communication portion between the large-diameter portion (2a) and the small-diameter portion (2b) as viewed from a direction of the piston axis. [5] A high-pressure fuel pump according to any one of claims 1 to 4, wherein a plurality of communication paths are formed at equal intervals in the circumferential direction as viewed from a direction of the piston axis. [6] High-pressure fuel pump according to one of claims 1 to 5, wherein the regulating element (16) is made of a cylindrical metal element and the end face (16c) is formed of a lower surface arranged to face the large diameter portion (2a) of the piston (2). [7] High-pressure fuel pump according to one of claims 1 to 6, further comprising: a seal holder (7) which holds the seal section (13) and forms the upper space (7a) of the small diameter section (2b), wherein the seal holder (7) is fixed to a pump body (1) forming the pressurizing chamber (11) and is adapted to support the regulating element (16) in an axial direction of the piston (2) on an inner peripheral side. [8] A high-pressure fuel pump according to any one of claims 1 to 7, wherein, in a direction of the piston axis, an outermost peripheral portion of the communication path (16d) is formed to overlap a recessed portion (13b) of the seal portion (13) which is recessed to a side opposite to the upper space (7a) of the seal portion (13).

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