CN114514372A

CN114514372A - Pumping unit for supplying a fluid, in particular a fuel, preferably diesel fuel, to a user device, in particular an internal combustion engine

Info

Publication number: CN114514372A
Application number: CN202080070478.5A
Authority: CN
Inventors: L·菲奥伦蒂诺
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-10-07
Filing date: 2020-09-30
Publication date: 2022-05-17
Also published as: WO2021069276A1; IT201900018122A1; EP4042010B1; EP4042010A1

Abstract

A pumping unit has a pre-feed pump (3) for supplying fuel to a high-pressure pump (2) provided with at least one cylinder (14) slidably engaged by a piston (15), and with a suction valve (29), the suction valve (29) having a closure member (34) slidably engaged through a valve body (31), a suction chamber (40) defined between the valve body (31) and the closure member (34), and at least one feed hole (38) formed through the valve body (31) for supplying fuel into the suction chamber (40), the suction chamber (40) having a wide portion (41) and a narrow portion (42) arranged in order from an outlet of the feed hole (38) to the cylinder (14).

Description

Pumping unit for supplying a fluid, in particular a fuel, preferably diesel fuel, to a user device, in particular an internal combustion engine

Technical Field

The invention relates to a pumping unit for supplying a fluid, in particular a fuel, preferably diesel fuel, to a user device, in particular an internal combustion engine.

The invention has particularly advantageous application in the feeding of fuel, preferably diesel fuel, to internal combustion engines, to which the following description refers in particular, but without thereby losing its general character.

Background

The pumping unit includes a high-pressure pump for supplying fuel to the internal combustion engine; and a low-pressure or pre-feed pump for feeding fuel from a storage tank to the high-pressure pump.

The high pressure pump is a piston pump, which includes a pump body; at least one cylinder formed in the pump body; a piston slidably engaged within the barrel; and actuating means for moving the cylinder in an alternating linear motion comprising an intake stroke for drawing fuel into the cylinder and a delivery stroke for supplying fuel to the internal combustion engine.

The high-pressure pump further includes an intake valve for selectively controlling the supply of fuel into the barrel; and a transfer valve for selectively controlling the supply of fuel to the internal combustion engine.

The suction valve includes a cylindrical valve body mounted and fixed within the pump body, and a closure member slidably engaged through the valve body to move between an open position and a closed position of the barrel.

When the closure member is arranged in its closed position, the closure member and the valve body engage each other in a fluid-tight manner in a sealing area defined by the respective engagement surfaces.

During use, the delivery stroke of each piston causes the associated suction valve to close. During the closing of the suction valve, a portion of the fuel compressed by the piston leaves the cylinder between the valve body and the closure member.

Known pumping units of the above-mentioned type have a number of drawbacks, mainly due to the fact that the fuel leaving the cylinder during the delivery stroke of the piston is subjected to cavitation in the above-mentioned sealing region, i.e. to the formation of vapour bubbles, which implode after the subsequent refilling of the cylinder with fuel pre-supplied by the pump, generate noise, cause wear and corrosion of said engagement surfaces, and therefore adversely affect the fluid-tight connection between the closure member and the valve body.

Disclosure of Invention

The object of the present invention is to provide a pumping unit for supplying a fluid, in particular a fuel, preferably diesel fuel, to a user device, in particular an internal combustion engine, which does not have the above-mentioned disadvantages and which can be produced simply and inexpensively.

According to the present invention, as claimed in the appended claims, a pumping unit for supplying a fluid, in particular a fuel, preferably diesel fuel, to a user device, in particular an internal combustion engine, is provided.

Drawings

The invention will now be described with reference to the accompanying drawings, which illustrate a non-limiting embodiment of the invention, in which:

figure 1 is a first schematic cross-sectional view, with parts removed for greater clarity, of a preferred embodiment of a pumping unit according to the invention;

fig. 2 is a schematic cross-sectional view of the pumping unit according to fig. 1, with parts removed for greater clarity;

FIG. 3 is an enlarged schematic cross-sectional view of a detail of the pumping unit shown in FIGS. 1 and 2;

figure 4 is a schematic cross-sectional view of a variant of the pumping unit according to figures 1 and 2, with parts removed for greater clarity; and

fig. 5 is an enlarged schematic cross-sectional view of a detail of the pumping unit shown in fig. 4.

Detailed Description

With reference to fig. 1 and 2, 1 denotes as a whole a pumping unit for feeding fuel, preferably diesel fuel, to an internal combustion engine (not shown).

The pumping unit 1 comprises a high-pressure pump 2 for supplying fuel to the internal combustion engine (not shown); and a low-pressure or pre-feed pump 3 for feeding fuel from a known storage tank (not shown) to said pump 2.

The high-pressure pump 2 is a piston pump having a pump body 4, the pump body 4 comprising a support housing 5, the support housing 5 being provided with a central hole 6 having a longitudinal axis 7, and with at least one lateral hole 8 (typically a plurality of lateral holes 8 uniformly distributed around the axis 7) having a longitudinal axis 9 transverse to the axis 7 and extending radially from said hole 6 towards the outside of the housing 5.

Each hole 8 is closed by a head member 10 arranged in contact with housing 5 and has a lug 11 projecting coaxially with axis 9 inside hole 8.

The head member 10 has a central hole 12, which central hole 12 is formed through the head member 10 coaxially to the axis 9 and comprises a wider portion 17a and a narrower portion 13b aligned with each other along said axis 9.

The narrower portion 13b faces the bore 6 and defines a barrel 14 of the piston pump 2.

Due to the thrust of the actuating means 16, the cylinder 14 is slidably engaged with a piston 15, which piston 15 has an alternating rectilinear movement comprising an intake stroke for drawing fuel into the cylinder 14 and a delivery stroke for supplying fuel to said internal combustion engine (not shown).

The device 16 comprises a tubular sleeve 17, which tubular sleeve 17 is slidably engaged in the bore 8 coaxially with the axis 9 and extends around the cylinder 14 and has an inner annular flange 18 projecting radially from the inner surface of the sleeve 17 and dividing said sleeve 17 into two

cylindrical portions

19, 20, of which portion 19 faces the bore 6.

The device 16 also has a tappet system 21, which tappet system 21 comprises a coupling block 27 having a substantially cylindrical shape, which coupling block 27 is locked by means of creating an interference in the portion 19 and is arranged to contact the flange 18 and support the tappet system roller 23.

The roller 23 projects from the block 22 towards the hole 6 and is rotatably coupled with the block 23 so as to rotate with respect to said block 22 about a longitudinal axis 24 substantially perpendicular to the axis 9.

The flange 18 supports an annular disc 25 extending around the piston 15, which annular disc 25 is inserted in the portion 20 of the sleeve 17 coaxially with the axis 9 and has an outer peripheral edge facing axially towards the flange 18 and an inner peripheral edge facing axially towards the head of said piston 15.

The device 16 further comprises a compression spring 26 mounted between the lug 11 and the sleeve 17 coaxially to the axis 9 and arranged between the head member 10 and the disc 25 so as to move the disc 25 and normally keep the disc 25 in contact with the flange 18, the roller 23 being in contact with a cam 27 formed on the outer surface of a central portion of the drive shaft mounted through the hole 6 so as to rotate about the axis 7 with respect to the housing 5.

The head member 10 houses therein an intake valve 29 for taking fuel into the barrel 14 and a delivery valve 30 for supplying fuel to an internal combustion engine (not shown).

The valve 29 is mounted in the wider portion 13a of the hole 12 and comprises a valve body 31 having a cylindrical shape, which extends around the axis 9 and is axially locked by a closing cap 33 screwed into said portion 13a, with respect to an annular shoulder 32 defined between the

portions

13a and 13 b.

The valve 29 also includes a closure member 34 mounted through the valve body 31 for movement between a closed position in which the closure member 34 is in fluid-tight engagement with the valve body 31 in a sealing region 35 to close the cartridge 14, and an open position.

In connection with the above description it should be pointed out that the sealing zone 35 may have the form of a circumferential line or a frustoconical surface.

The closure member 34 is moved and normally maintained in its closed position by a spring 36, which is arranged between the valve body 31 and an annular disc 37 mounted to the closure member 34 transversely with respect to the axis 9.

According to fig. 3, the valve body 31 has a plurality of inlet openings 38, which inlet openings 38 are distributed about the axis 9 and have, in the case in question, a respective longitudinal axis 39, which longitudinal axis 39 is substantially radial and transverse to the axis 9.

According to a variant (not shown), the axis 39 of the hole 38 is inclined with respect to the axis 9 and directed towards the cylinder 14.

The valve body 31 defines, together with the closure member 34, a suction chamber 49, which suction chamber 49 is configured to have a relatively wide portion 41 and a relatively narrow portion 42, arranged in sequence from the outlet of the bore 38 to the sealing zone 35.

In other words, at the outlet of the hole 38, the fuel is first fed through the wide portion 41 and then through the narrow portion 42, the passage section of the narrow portion 42 being smaller than that of said wide portion 41.

The variant shown in figures 4 and 5 differs from that shown in the preceding figures in that the valve body 31 is incorporated in the head member 10 and is made integral with said head member 10, and in that the axis 39 of the hole 38 is inclined with respect to the axis 9.

Also in this case, at the outlet of the hole 38, the fuel passes first through the wide portion 41, then through the narrow portion 42 and finally into the cylinder 14.

The pumping unit 1 has a number of advantages, mainly due to the configuration of the suction chamber 40:

cavitation affecting the fuel discharged from the cylinder 14 during the delivery stroke of the piston 15 is concentrated at the wide portion 41;

preventing cavitation from concentrating on the sealing area 35;

wear of the valve body 31 and the closure member 34 is avoided in the region 35;

when the closure member 34 is arranged in its closed position, a correct fluid tight engagement between the valve body 31 and the closure member 31 is ensured.

Claims

1. A pumping unit for supplying a fluid, in particular a fuel, preferably diesel fuel, to a user device, in particular an internal combustion engine, the pumping unit comprising a high-pressure pump (2) for supplying the fluid to the user device; and a pre-feed pump (3) for feeding fluid to the high-pressure pump (2), the high-pressure pump (2) in turn comprising: a pump body (4); at least one cylinder (14) formed in the pump body (4); a piston (15) slidably engaged within the barrel (14); and a suction valve (29) for selectively controlling the supply of fluid to the cylinder (14), the suction valve (29) in turn comprising: a valve body (31); a closure member (34) slidably engaged through the valve body (31); a suction chamber (40) defined between the valve body (31) and the closure member (34); and at least one inlet hole (38) formed through the valve body (31) for supplying a fluid into the suction chamber (40), characterized in that the suction chamber (40) is configured to have a relatively wide portion (41) and a relatively narrow portion (42) which are arranged in order from an outlet of the inlet hole (38) to the cylinder (14).

2. Pumping unit according to claim 1, wherein the closure member (34) is movable between a closed position, in which the closure member (34) is in fluid-tight engagement with the valve body (31) in a sealing zone (35), and an open position; the wide portion (41) and the narrow portion (42) are arranged in order from the outlet of the feed opening (38) to the sealing area (35).

3. Pumping unit according to claim 1 or 2, wherein the passage section of the wide portion (41) is greater than the passage section of the narrow portion (42).

4. Pumping unit according to any of the preceding claims, wherein the valve body (31) is mounted and locked within the pump body (4).

5. Pumping unit according to any of claims 1 to 3, wherein said valve body (31) is incorporated in said pump body (4) and is made in one piece with said pump body (4).

6. Pumping unit according to any one of the preceding claims, wherein each feeding hole (38) has a longitudinal axis (39) arranged transversally with respect to the longitudinal axis (9) of the cylinder (14).

7. Pumping unit according to any one of claims 1 to 5, wherein each feeding hole (38) has a longitudinal axis (39) inclined with respect to the longitudinal axis (9) of the cylinder (14).