JP7002870B2 - Fuel pump - Google Patents

Description

The present invention relates to a fuel pump.

For example, Patent Document 1 discloses a high-pressure pump (fuel pump) in which a pressurizing chamber for pressurizing fuel by reciprocating movement of a plunger and a discharge passage for discharging high-pressure fuel are formed. In such a high-pressure pump, a return passage (relief flow path) is formed in which the fuel flows back from the discharge flow path to the pressurizing chamber when the fuel flowing into the discharge flow path becomes higher than a predetermined value. ing. Further, the return passage is provided with a relief valve that opens when the fuel pressure exceeds a predetermined value.

Japanese Unexamined Patent Publication No. 2010-156256

By the way, in a fuel pump in which a fuel chamber in which fuel is stored is formed in front of the pressurizing chamber, a relief flow path connecting the discharge flow path and the fuel chamber may be formed. In the case of such a structure, the high-pressure fuel in the discharge flow path flows into the combustion chamber through the relief flow path. The fuel in the fuel chamber has a lower pressure than the high pressure fuel in the discharge flow path, and the volume of the fuel chamber is wider than that in the discharge flow path. Therefore, the high-pressure fuel flowing in through the relief flow path is rapidly depressurized in the fuel chamber, and cavitation occurs in the fuel chamber. Bubbles generated by cavitation cause erosion and, in long-term use, can cause performance degradation due to thinning of parts in the fuel chamber, especially dampers made of thin plates.
Today, the pressure of the supplied fuel is increasing in order to improve the performance of the internal combustion engine, and strong cavitation is likely to occur in the fuel chamber.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to suppress erosion in the fuel chamber and prevent deterioration of the performance of parts in the fuel chamber in the fuel pump.

In order to achieve the above object, in the present invention, as the first means, a fuel chamber in which a damper for absorbing the pressure pulsation of the fuel in which the fuel is stored is installed, and a plunger slidably held inside the cylinder. The volume is reduced by the pressurization stroke of the plunger in the previous term, the pressurization chamber where the fuel is pressurized, the fuel discharge flow path connected to the pressurization chamber, and the fuel chamber connected downstream and upstream. A fuel pump having a relief flow path connected to the fuel discharge flow path and provided with a relief valve in the relief flow path, wherein the relief flow path is provided with the relief valve internally. The first flow path provided with the relief valve and the second flow path connected downstream of the relief valve of the first flow path at an angle with respect to the direction in which the first flow path extends. The configuration of having and is adopted.

As a second means, in the first means, the first flow path has a relaxation space extending downstream of the relief valve, and the second flow path includes the relaxation space and the relief valve. A configuration is adopted in which the space is connected to the first flow path.

As a third means, in the first or second means, the relief flow path connects the second flow path and the fuel chamber, and the flow path diameter is reduced with respect to the second flow path. A configuration is adopted in which the throttle flow path is provided.

As a fourth means, in any of the first to third means, the relief flow path has a volume on the downstream side of the relief valve of the fuel discharged from the pressurizing chamber in the pressurizing stroke. Adopt a configuration that is larger than the maximum volume.

According to the present invention, since the first flow path and the second flow path are connected at an angle, the jet of high-pressure fuel flowing into the first flow path enters the second flow path. It gradually flows into the fuel chamber while being weakened. Therefore, the fuel flowing from the discharge flow path to the relief flow path is gradually weakened, so that bubbles generated by cavitation can be eliminated in the relief flow path and erosion in the fuel chamber is suppressed. be able to.

It is sectional drawing which shows the schematic structure of the plunger pump in one Embodiment of this invention. It is an enlarged sectional view including a part of the suction mechanism provided in the plunger pump in one Embodiment of this invention. It is an enlarged sectional view including a part of the body which a plunger pump has in one Embodiment of this invention.

Hereinafter, an embodiment of a fuel pump and a method for manufacturing a fuel pump according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member recognizable. Further, in the following embodiments, an example in which the fuel pump of the present invention is applied to a plunger pump will be described.

FIG. 1 is a cross-sectional view showing a schematic configuration of the plunger pump 1 of the present embodiment. As shown in this figure, the plunger pump 1 of the present embodiment includes a body 2, a suction mechanism 3, a boosting mechanism 4, a discharge mechanism 5, and a damper mechanism 6. In the following description, the axis of the plunger (pressurizing plunger 4b) that pressurizes the fuel is referred to as the central axis L, and the direction orthogonal to the central axis L is referred to as the body radial direction, and the central axis L side in the body radial direction. Is referred to as the inside in the radial direction of the body, and the side opposite to the central axis L in the radial direction of the body is referred to as the outside in the radial direction of the body. Although the installation posture of the plunger pump 1 is not limited, the upper side in FIG. 1 is referred to as an upper side and the lower side in FIG. 1 is referred to as a lower side for convenience of explanation.

The body 2 (cylinder) is a base to which a suction mechanism 3, a booster mechanism 4, a discharge mechanism 5, and a damper mechanism 6 are attached, and a fuel flow path for guiding fuel is formed therein. As shown in FIG. 1, in the plunger pump 1 of the present embodiment, as a fuel flow path, a suction flow path R1 into which a part of the suction mechanism 3 is fitted and a discharge flow into which a part of the discharge mechanism 5 is fitted. A path R2 (fuel discharge flow path) is formed inside the body 2. Further, inside the body 2, a pressurizing chamber R3 that connects the suction flow path R1 and the discharge flow path R2 and pressurizes the fuel is provided. The pressurizing chamber R3 is a space arranged in the central portion of the body 2 in the radial direction of the body and surrounded by the inner wall of the body 2 and the boosting plunger 4b described later, and the volume changes due to the movement of the boosting plunger 4b. ..

Further, the body 2 has a penetrating space R5 that penetrates downward from the pressurizing chamber R3 and movably accommodates the boosting plunger 4b described later. Further, the body 2 has a spring holding portion 2b that extends into the suction flow path R1 and is arranged to face the suction valve body 3b described later from the downstream side (inside the body radial direction) in the fuel flow direction. ing. The spring holding portion 2b is attached with a suction spring 3c described later for urging the suction valve body 3b, and also serves as a stopper for restricting the movement of the suction valve body 3b from the downstream side (inside in the body radial direction) in the fuel flow direction. Also works.

FIG. 3 is an enlarged cross-sectional view including a part of the body 2 of the plunger pump 1 in the present embodiment. As shown in this figure, the body 2 is formed with a relief flow path R6 that communicates the discharge flow path R2 and the damper chamber Rd (fuel chamber), and the connection end of the relief flow path R6 with the damper chamber Rd. 2c is provided with a substantially cylindrical throttle flow path forming member 2c. The relief flow path R6 has a first flow path R6a, a second flow path R6b, and a throttle flow path R6c. The first flow path R6a is a flow path in which one end is connected to the discharge flow path R2 and is formed toward the inside in the radial direction of the body. Further, the first flow path R6a is provided with a relief valve 5f, which will be described later, and is connected to the second flow path R6b. In the body radial direction, the end opposite to the end on the side connected to the discharge flow path R2. A relaxation space R6d is formed between the portion and the connection portion between the portion and the second flow path R6b.

The second flow path R6b is formed in a direction along the axis of the central axis L so as to be connected to the first flow path R6a substantially orthogonally, and is connected to the throttle flow path R6c at the upper end. Has been done. Further, the second flow path R6b has a larger flow path diameter and a larger overall volume as compared with the first flow path R6a. Further, the total volume of the first flow path R6a and the second flow path R6b is set to be larger than the maximum volume in the pressurizing chamber R3. The throttle flow path R6c is connected to the second flow path R6b and the damper chamber Rd, and the flow path diameter is reduced by the throttle flow path forming member 2c as compared with the first flow path R6a and the second flow path R6b. It is diametered.

FIG. 2 is an enlarged cross-sectional view including a part of the suction mechanism 3. As shown in this figure, in the present embodiment, the suction flow path R1 formed inside the body 2 is gradually shrunk coaxially from the outer wall portion of the body 2 toward the central portion (pressurization chamber R3). It is diametered and has a region R1a, a region R1b, a region R1c, a region R1d and a region R1e. The region R1a located on the outermost side in the radial direction of the body accommodates the tip portion of the base portion 3e, which will be described later, of the suction mechanism 3. The region R1b arranged on the inner side in the radial direction of the body next to the region R1a has a smaller diameter than the region R1a and is connected to the supply flow path R4. The region R1c arranged on the inner side in the radial direction of the body next to the region R1b has a smaller diameter than the region R1b, and accommodates the valve seat 3a of the suction mechanism 3. The region R1d arranged on the inner side in the radial direction of the body next to the region R1c has a smaller diameter than the region R1c, and connects the region R1c and the region R1e. The region R1e arranged on the inner side in the radial direction of the body next to the region R1c and arranged on the most central side of the body 2 has a smaller diameter than the region R1d, and connects the region R1d and the pressurizing chamber R3. There is. The above-mentioned spring holding portion 2b is arranged in this region R1d.

As shown in FIG. 2, the suction mechanism 3 includes a valve seat 3a, a suction valve body 3b, a suction spring 3c, and a solenoid unit 3d. The valve seat 3a is arranged in the suction flow path R1 and has an opening that is opened and closed by the suction valve body 3b. The suction valve body 3b is arranged inside the valve seat 3a in the radial direction of the body, and is movably held by the suction spring 3c in the radial direction of the body. The suction spring 3c is held by externally fitting the inner end portion in the radial direction of the body to the spring holding portion 2b of the body 2, and the outer end portion in the radial direction of the body is provided at the center of the suction valve body 3b. It is externally fitted to the part. The suction spring 3c is a compression coil spring that can be contracted by a differential pressure when the pressure on the upstream side of the suction valve body 3b becomes relatively higher than the pressure on the downstream side. It is urged toward the outside in the radial direction of the body.

The solenoid unit 3d includes a base portion 3e, a guide member 3f, a suction plunger 3g, a solenoid spring 3h, a movable core 3i, a coil 3j, a fixed core 3k, and a connector 3m. The base portion 3e is fixed to the body 2 and directly or indirectly supports the guide member 3f, the suction plunger 3g, the solenoid spring 3h, the movable core 3i, the coil 3j, the fixed core 3k, and the connector 3m. The base portion 3e is set in a substantially cylindrical shape having a through hole formed in the central portion, and the tip portion thereof is inserted into the suction flow path R1 of the body 2 from the outside in the radial direction of the body.

The guide member 3f is a substantially cylindrical component arranged coaxially with the base portion 3e, and is internally fitted in a through hole provided in the base portion 3e. The guide member 3f is provided with a tubular portion 3f1 having a through hole into which the suction plunger 3g is movably inserted in the radial direction of the body, and a guide flange that is provided so as to project from the outer peripheral surface of the tubular portion 3f1 and is fixed to the base portion 3e. It has 3f2.

The suction plunger 3g has a shaft portion 3g1 and a plunger flange 3g2. The shaft portion 3g1 is movably inserted into the through hole of the tubular portion 3f1 of the guide member 3f, and is a rod-shaped portion longer than the guide member 3f in the radial direction of the body. The shaft portion 3g1 has an end portion inside the body radial direction further inside the body radial direction than the guide member 3f, and an end portion outside the body radial direction further outside the body radial direction than the guide member 3f.

The plunger flange 3g2 is a plate-shaped portion provided so as to project from the outer peripheral surface of the shaft portion 3g1, and is arranged at a position inside the guide member 3f in the radial direction of the body. Such a suction plunger 3g is movable in the body radial direction between the end surface of the guide member 3f on the inner side in the body radial direction and the end surface of the valve seat 3a on the outer side in the body radial direction. Further, when the plunger flange 3g2 abuts on the valve seat 3a from the outside in the radial direction of the body, the suction plunger 3g is restricted from moving inward in the radial direction of the body, and the plunger flange 3g2 hits the guide member 3f from the inside in the radial direction of the body. When in contact, movement to the outside in the radial direction of the body is restricted. Further, in the suction plunger 3g, when the plunger flange 3g2 abuts on the valve seat 3a, the end face on the inner side in the body radial direction of the shaft portion 3g1 can abut on the suction valve body 3b in the closed posture. ..

The movable core 3i is fixed by inserting the outer end portion of the shaft portion 3g1 of the suction plunger 3g in the radial direction of the body. The solenoid spring 3h is a compression coil spring that is externally fitted to the tubular portion 3f1 of the guide member 3f. It is in contact with a 3 g plunger flange 3 g 2. Such a solenoid spring 3h urges the suction plunger 3g inward in the radial direction of the body. Such a solenoid spring 3h urges the suction plunger 3g inward in the radial direction of the body so that the suction valve body 3b is in the open posture when the coil 3j is not energized.

The coil 3j has a substantially cylindrical shape in which windings are wound with a diameter substantially the same as that of the base portion 3e, and is connected to an end portion of the base portion 3e on the outer side in the radial direction of the body. The coil 3j generates a magnetic field when it is energized from the outside via the connector 3m. The fixed core 3k is arranged inside the coil 3j so as to close the opening provided in the center of the coil 3j from the outside in the radial direction of the body. The connector 3m is supported by the fixed core 3k and is electrically connected to the coil 3j. The connector 3m is connected to a power supply device (for example, an in-vehicle battery) installed outside the plunger pump 1 of the present embodiment.

Returning to FIG. 1, the boosting mechanism 4 includes a barrel 4a, a boosting plunger 4b, a lower flange 4c, and a boosting spring 4d. The barrel 4a is internally fitted in the penetration space R5 of the body 2 and is a tubular component that guides the raising and lowering of the step-up plunger 4b. The booster plunger 4b is held so as to be able to move up and down so that the upper end surface of the booster plunger 4b faces the pressurizing chamber R3 of the body 2. The lower end surface of the boost plunger 4b is in contact with a cam (not shown) via a lifter (not shown), and when the cam is rotated by the drive of an engine mounted on a vehicle, the step-up plunger 4b moves up and down according to the rotation of the cam. Will be done. The lower flange 4c is connected to the lower end portion of the booster plunger 4b, and projects outward from the peripheral surface of the booster plunger 4b in the radial direction of the body. The booster spring 4d is a compression coil spring inserted between the body 2 and the lower flange 4c, and urges the booster plunger 4b downward via the lower flange 4c. In such a boosting mechanism 4, the boosting plunger 4b rises to reduce the volume of the pressurizing chamber R3, thereby boosting the fuel in the pressurizing chamber R3.

The discharge mechanism 5 includes a discharge nozzle 5a, a discharge valve seat 5b, a discharge valve body 5c, a spring accommodating portion 5d, a discharge spring 5e, and a relief valve 5f. The discharge nozzle 5a is a substantially cylindrical component fixed to the body 2 so as to be connected to the discharge flow path R2, and discharges the fuel boosted by the plunger pump 1 of the present embodiment to the outside.

The discharge valve seat 5b is located inside the discharge flow path R2 and is located closest to the pressurizing chamber R3 (inward in the radial direction of the body) among the components of the discharge mechanism 5. The discharge valve seat 5b has an opening that is opened and closed by the discharge valve body 5c. The discharge valve body 5c is arranged outside the body radial direction of the discharge valve seat 5b, and is held so as to be movable in the body radial direction by the discharge spring 5e. The spring accommodating portion 5d is externally fitted to the discharge valve seat 5b so as to surround the discharge valve body 5c, and houses the discharge valve body 5c and the discharge spring 5e inside. The spring accommodating portion 5d has a substantially cylindrical shape having through holes on the peripheral surface, the bottom surface, and the like, and allows fuel to pass from the inside to the outside. The discharge spring 5e is a compression coil spring inserted between the inner wall surface of the spring accommodating portion 5d and the discharge valve body 5c, and the discharge valve body 5c is attached toward the inside in the body radial direction (discharge valve seat 5b side). It is gaining momentum.

As shown in FIG. 3, the relief valve 5f is provided in the first flow path R6a, and is provided with a relief valve seat 5f1, a relief valve body 5f2 (valve body), a relief spring 5f3 (urging member), and a spring retainer 5f4. And have. The relief valve seat 5f1 is a substantially annular member arranged on the discharge flow path R2 side of the first flow path R6a and having an opening opened and closed by the relief valve body 5f2. The relief valve body 5f2 is a substantially spherical member, and is arranged on the downstream side of the relief valve seat 5f1 in the first flow path R6a, that is, on the second flow path R6b side. The relief valve body 5f2 abuts on the relief valve seat 5f1 by being urged by the relief spring 5f3 in a state where the fuel pressure in the discharge flow path R2 is less than a predetermined value, and shields the opening of the relief valve seat 5f1. ..

The relief spring 5f3 urges the relief valve body 5f2 in the valve closing direction, and contracts due to the differential pressure when the pressure on the upstream side of the relief valve body 5f2 becomes relatively higher than the pressure on the downstream side. do. The spring retainer 5f4 is a member provided between the relief valve body 5f2 and the relief spring 5f3 and transmitting the urging force of the relief spring 5f3 to the relief valve body 5f2.
Such a relief valve 5f is opened by the fuel pressure when the pressure of the high-pressure fuel in the discharge flow path R2 becomes a predetermined value or more, and the high-pressure fuel flows into the relief flow path R6.

As shown in FIG. 1, the damper mechanism 6 includes a cover 6a, a seat spring 6b, a retainer 6c, and a pulsation damper 6d. The cover 6a has a dome shape and is fixed to the surrounding wall portion 2a of the body 2 so as to form a damper chamber Rd with the body 2. The seat spring 6b is placed on the bottom of the damper chamber Rd (that is, the top surface of the body 2). The seat spring 6b is arranged below the retainer 6c and urges the retainer 6c toward the inner wall surface of the cover 6a. The retainer 6c is a substantially ring-shaped member that holds the pulsation damper 6d, and a plurality of through holes are formed with respect to the peripheral surface. The pulsation damper 6d is a member in which two diaphragms are bonded in the vertical direction so as to form an internal space, and is housed in a region surrounded by the retainer 6c. The pulsation damper 6d is compressed or expanded according to the pressure of the damper chamber Rd, and absorbs the pressure pulsation of the fuel in the damper chamber Rd.

In the plunger pump 1 of the present embodiment having such a configuration, the energization of the coil 3j of the suction mechanism 3 is stopped (or energized) at the timing when the booster plunger 4b is lowered and the pressure of the pressurizing chamber R3 is lowered. Reduce the amount of current that is generated). As a result, the suction plunger 3g is moved inward in the radial direction of the body by the restoring force of the solenoid spring 3h, and a gap is formed between the valve seat 3a and the suction valve body 3b. When a gap is formed between the valve seat 3a and the suction valve body 3b, the fuel stored in the damper chamber Rd is supplied to the pressurizing chamber R3 through the supply flow path R4 and the suction flow path R1. The suction plunger 3g is pulled back to the outside in the radial direction of the body in a very short time by energizing the coil 3j, but until the booster plunger 4b rises and the volume of the pressurizing chamber R3 is reduced, the valve seat 3a and the suction plunger 3g are pulled back. The open state of the suction valve body 3b is maintained by the pressure of the fuel flowing in the gap between the suction valve body 3b and the suction valve body 3b.

When the booster plunger 4b rises and the volume of the pressurizing chamber R3 is reduced, the suction valve body 3b is pushed back outward in the radial direction of the body, the suction valve body 3b is closed, and the fuel in the pressurizing chamber R3 is boosted. Will be done. Until the suction valve body 3b is completely closed, a part of the fuel in the pressurizing chamber R3 flows back to the damper chamber Rd through the suction flow path R1 and the supply flow path R4. At this time, the pulsation damper 6d is compressed, whereby the pressure fluctuation of the damper chamber Rd is absorbed.

When the fuel is boosted in the pressurizing chamber R3, the discharge valve body 5c of the discharge mechanism 5 is pressed outward in the radial direction of the body, and a gap is formed between the discharge valve body 5c and the discharge valve seat 5b. As a result, the fuel boosted in the pressurizing chamber R3 is discharged to the outside of the plunger pump 1 of the present embodiment through the discharge flow path R2 and the discharge nozzle 5a.

Further, when the pressure of the high-pressure fuel flowing into the discharge flow path R2 rises above a predetermined value, the relief valve body 5f2 is pushed downstream by the fuel, and the relief spring 5f3 is compressed via the spring retainer 5f4. It moves away from the relief valve seat 5f1 and moves to the downstream side. As a result, the relief valve 5f is opened, and the high-pressure fuel flows into the first flow path R6a. Since the second flow path R6b is formed substantially perpendicular to the first flow path R6a, the jet of high-pressure fuel constitutes a flow path at the connection portion between the first flow path R6a and the second flow path R6b. Heading upward while colliding with the wall. At this time, since the total volume of the first flow path R6a and the second flow path R6b is larger than the stroke volume of the pressurizing chamber R3, the fuel flowing into the first flow path R6a and the second flow path R6b is pressurized again. When the fuel is pressurized in the chamber R3 and the pressure of the high-pressure fuel flowing into the discharge flow path R2 can rise above a predetermined value, the fuel stays in the relief flow path R6, and when further fuel flows in from the pressurizing chamber R3, It is extruded from the first flow path R6a and the second flow path R6b, passes through the throttle flow path R6c, and flows into the damper chamber Rd.

According to the plunger pump 1 according to the present embodiment, since the second flow path R6b is connected to the first flow path R6a at an angle, the discharge flow path R2 is connected to the relief flow path R6. The jet of high-pressure fuel that flows in cannot go straight and enter the damper chamber Rd, and collides with the wall surface constituting the relief flow path R6 when flowing from the first flow path R6a to the second flow path R6b. At the same time, the momentum is weakened by mixing with the low-pressure fuel that has been filled in the relief flow path in advance. In general, erosion occurs when bubbles due to cavitation collide vigorously, causing the bubbles to collapse. do not have. Therefore, erosion in the damper chamber Rd can be suppressed.

Further, according to the plunger pump 1 according to the present embodiment, the first flow path R6a has a relaxation space R6d extending downstream of the relief valve 5f, and the second flow path R6b has a relaxation space R6d and a relief valve. It is connected to the first flow path R6a between 5f and 5f. As a result, the jet of high-pressure fuel flowing from the discharge flow path R2 into the relief flow path R6 enters the relaxation space R6d while maintaining its momentum, and then is repelled at the bottom of the relaxation space R6d, so that the relaxation space is previously repelled. It will mix more strongly with the low pressure fuel filled in R6d. As a result, the jet of high-pressure fuel is further weakened, so that erosion in the damper chamber Rd can be suppressed.

Further, according to the plunger pump 1 according to the present embodiment, the relief flow path R6 has a throttle flow path R6c. As a result, when the high-pressure fuel flows into the relief flow path R6, the fuel previously filled in the relief flow path R6 is prevented from flowing out from the relief flow path R6 by the throttle flow path R6c, and the relief flow. The pressure in the road R6 will rise temporarily. Therefore, the pressure difference of the high-pressure fuel flowing from the discharge flow path R2 into the relief flow path R6 is reduced, and the generation of bubbles due to cavitation in the relief flow path R6 can be suppressed. As a result, it is possible to prevent bubbles from reaching the damper chamber Rd due to cavitation and suppress erosion in the damper chamber Rd.

Further, according to the plunger pump 1 according to the present embodiment, the total volume of the first flow path R6a and the second flow path R6b is larger than the stroke volume in the pressurizing chamber R3. Therefore, the high-pressure fuel that has flowed into the relief flow path R6 in one pressurization stroke stays in the relief flow path R6 until the next pressurization stroke is started in the pressurizing chamber R3, and bubbles generated by cavitation are generated. You can get time to reduce. This also prevents air bubbles from reaching the damper chamber Rd due to cavitation, and suppresses erosion in the damper chamber Rd.

Further, according to the plunger pump 1 according to the present embodiment, the relief valve 5f provided in the first flow path R6a has a relief spring 5f3 that urges the relief valve body 5f2 into a closed state. Therefore, the relief valve 5f is adjusted so that when the pressure of the fuel in the discharge flow path R2 becomes a predetermined pressure, the fuel flows into the relief flow path R6 by the pressure of the fuel without using a sensor or the like. be able to.

Further, with such a configuration, the pressure of the fuel flowing into the damper chamber Rd can be reduced, and it is possible to suppress the high pressure applied to the members in the damper chamber Rd in the damper chamber Rd. can. Therefore, in the damper chamber Rd, it is possible to use a member having a lower pressure resistance performance as compared with the conventional one, and it is possible to reduce the manufacturing cost.

Although the preferred embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the above embodiment. The various shapes and combinations of the constituent members shown in the above-described embodiment are examples, and can be variously changed based on design requirements and the like without departing from the spirit of the present invention.

(1) In the above embodiment, in the relief flow path R6, the total volume of the first flow path R6a and the second flow path R6b is set to be larger than the stroke volume of the pressurizing chamber R3. Not limited to this. The total volume of the first flow path R6a and the second flow path R6b can be arbitrarily set according to the pressure of the fuel in the damper chamber Rd.

(2) Further, in the above embodiment, the throttle flow path R6c has a structure in which the flow path diameter is smaller than that of the first flow path R6a, but the present invention is not limited thereto. It is also possible to adopt a configuration in which the flow path diameter of the throttle flow path R6c is larger than that of the first flow path R6a.

(3) Further, in the above embodiment, the damper chamber Rd (fuel chamber) is provided with a pulsation damper 6d having two diaphragms, but the present invention is not limited thereto. The shape and configuration of the pulsation damper 6d are not limited.

(4) Further, in the above embodiment, an example in which the present invention is applied to the plunger pump 1 has been described, but the present invention is not limited thereto. The present invention can be any configuration as long as it is a fuel pump having a solenoid valve and has a discharge flow path and a fuel chamber.

1 ... Plunger pump 2 ... Body 3 ... Suction mechanism 4 ... Boost mechanism 5 ... Discharge mechanism 5f ... Relief valve R1 ... Suction flow path R2 ... Discharge flow path R3 ... Pressurization chamber R4 ... Supply flow path R5 …… Through space R6 …… Relief flow path R6a …… First flow path R6b …… Second flow path R6c …… Flow path R6d …… Relaxation space Rd …… Damper room

Claims (1)

The fuel chamber is equipped with a damper that absorbs the pressure pulsation of the fuel in which the fuel is stored, the plunger that is slidably held inside the cylinder, and the volume is reduced by the pressurizing stroke of the plunger, and the fuel is pressurized. A pressurizing chamber is formed, a fuel discharge flow path connected to the pressurizing chamber, and a relief flow path connected to the fuel chamber downstream and connected to the fuel discharge flow path upstream. A fuel pump provided with a relief valve provided in the relief flow path.
The relief flow path has an angle with respect to the direction in which the first flow path extends with respect to the first flow path in which the relief valve is installed and the relief valve is provided. It has a second flow path connected to the downstream side of the relief valve, and is arranged in the second flow path and connected to the fuel chamber, and the flow path diameter is reduced with respect to the second flow path. A throttle passage forming member having a throttle passage is provided, and the volume from the relief valve to the throttle flow path is larger than the maximum volume of fuel discharged from the pressurizing chamber in the pressurization stroke.
The first flow path has a relaxation space extending downstream from the relief valve.
The second flow path is connected to the first flow path between the relaxation space and the relief valve.
The throttle passage forming member has an outer diameter substantially the same as the maximum diameter of the second flow path, and is arranged on the fuel chamber side of the second flow path.
A fuel pump characterized by that.

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