KR20190124811A - Fuel pump for fueling internal combustion piston engines - Google Patents

Abstract

The present invention relates to a fuel pump (10) for supplying fuel to an internal combustion piston engine, the fuel pump (10) having a body (18) and a cylindrical space (30) having a central axis (32) in the body, And a piston member 28 arranged to reciprocate in the cylindrical space 30, wherein the piston member is provided with a sleeve member 46 having a closed end arranged in the second space section 30 ''. Provided, an annular space is provided between the sleeve member 46 and the piston member 28, the pump including an annular gap at least partially surrounding the piston member 28, the sleeve member being annular. Arranged so as to extend into the gap, the third space section 60 is arranged bordered by the sleeve member 46, and the third space section 60 includes a lubricant supply channel 62 and a lubricant discharge channel 64. Connected.

Description

Fuel pump for fueling internal combustion piston engines

The present invention relates to a fuel pump for supplying fuel to an internal combustion piston engine, the fuel pump comprising a body and a cylindrical space having a central axis within the body, and a piston member arranged to reciprocate in the cylindrical space. And the cylindrical space includes a first space section having a first diameter, wherein the wall of the cylindrical space and the wall of the piston member are relative to each other such that the wall of the cylindrical space guides the piston member in the body. A first end of a piston member arranged to provide a first sealing gap, the first space section forming a first pumping chamber of a pump configured to pump the fuel as the piston reciprocates in the cylindrical space Bounded by

The internal combustion piston engine needs to be provided with one or more fuel pumps. Fuel injection into the engine's fuel chambers, in particular in so-called common rail systems, requires the ability to pump fuel even at high pressures above 250 MPa. Since the pump is typically lubricated by the lubricating oil of the engine, the presence of both fuel and lubricating oil in the pump may require special attention, particularly with regard to preventing or minimizing the mixing of fuel and lubricant in the pump.

Document EP 0976926 B1 discloses an integral pump and tappet unit for fueling an internal combustion engine, such as a large diesel engine, wherein the unit has a tappet in which axial movement is governed by the movement of the cam surface provided on the camshaft or the like. A body portion surrounding the member and a piston member operatively connected to the tappet member and arranged to pump fuel under high pressure from a fuel chamber arranged in the body portion. The body portion is a single member for receiving both the tappet member and the fuel chamber, wherein the tappet member and the piston member are connected to each other by a tappet arm sealed to a flange member fixed to the body portion so that fuel from the fuel chamber contacts the tappet member. Is prevented.

Document DE 102015002304 A1 discloses a high pressure fuel pump. The literature does not mention possible leakage of fuel into the lubricating oil but shows the lubrication system of the pump. The pump includes a pump housing having an interior space, a pump plunger having a guide surface guided in the interior space of the pump housing, a lubricant line opening into the interior space opposite the guide surface of the plunger, and aeration through which lubricant can be discharged from the spring chamber. And a pipe, said interior space and said pump plunger defining a spring chamber of a high pressure fuel pump.

Document DE 102008042067 A1 discloses a pump having a drive shaft with an eccentric cam and a piston housed in a cylinder. The document discloses round membrane seals used to separate fuel and lubrication systems from one another.

Document DE 102006059333 A1 discloses a fuel pump comprising at least one wiper element integrated in the pump piston to remove leaked fuel collected between the pump piston and the pump cylinder from the cylinder wall. The wiper element is a scraper ring that removes leaking fuel accumulating in the wall of the pump cylinder and directs it to at least one leaking groove.

US 7308849 defines a working chamber and is also indirectly driven by the drive shaft in reciprocating motion against the force of the restoring spring. The pump piston is braced at least indirectly to the drive shaft via a sleeve, such as a tappet, and the restoring spring engages at least the pump piston. The support element in the tappet braces the pump piston towards the drive shaft and is also braced at least indirectly in the drive shaft. The return spring engages the pump piston and tappet through the spring plate. The spring plate is elastically deformable in the direction of motion of the pump piston so that the deviation is compensated for at the position of the contact surface on the pump piston and on the tappet as a result of the elastic deformation.

WO 2011160908 A1 discloses a pump comprising at least one pump element having a pump piston driven at least indirectly in stroke movement by a drive shaft. A plunger having a plunger body is arranged between the drive shaft and the pump piston, and is movably guided in the receiving device in the direction of stroke movement of the pump piston and is also supported on the drive shaft by a support element. Lubricant is supplied to the receiving device via a supply line, and the lubricant is also guided to the support element via a discharge line from the receiving device to the plunger body. An annular gap filter is provided between the plunger body and the receiving device and is also arranged between a supply line for supplying lubricant to the receiving device and a discharge line for discharging the lubricant to the plunger body.

It is an object of the present invention to provide a fuel pump for supplying fuel to an internal combustion piston engine, the performance of which is significantly improved over the prior art solutions.

The objects of the present invention can be substantially met as disclosed in the independent claims and in the other claims describing the details of different embodiments of the invention.

A fuel pump for supplying fuel to the internal combustion piston engine includes a body and a cylindrical space arranged in the body and having a central axis, and a piston member arranged to reciprocate in the cylindrical space, the cylindrical space having a first diameter. And a first space section having a wall of the cylindrical space and the wall of the piston member arranged relative to each other such that the wall of the cylindrical space guides the piston member in the body and provides a first sealing gap. And the first space section is bounded by a first end of the piston member that forms a first pumping chamber of the fuel pump configured to pump fuel as the piston member reciprocates in the cylindrical space. . The piston member is provided with a sleeve member extending toward the first end of the piston member, so that an annular space is provided between the sleeve member and the piston member, and the annular space defines the first end of the piston member. The inner wall of the second space section and the radial outer wall of the sleeve member are arranged with respect to each other such that the inner wall of the second space section guides the sleeve member in the second space section. A gap, and an annular third space section is arranged into the fuel pump, and the third space section is arranged on an inner wall of the sleeve member and the second space section arranged to extend into the annular third space section. Partially bounded and connected to the third space section by a lubricant supply channel and a lubricant discharge channel. All.

According to an embodiment of the present invention, the second space section includes a second pumping chamber of the fuel pump configured to pump fuel material from the second space section as the piston member reciprocates in the cylindrical space. Is provided.

According to an embodiment of the invention, the second space section is provided with a second pumping chamber of the pump configured to pump fuel from the second space section as the piston member reciprocates in the space, The pump includes a vent flow path connecting the second space section out of the body to allow gas inflow into the second space section driven by the reciprocating motion of the piston member, and from the second space section. A discharge flow path is provided that connects the second space section out of the body to transfer fuel material away.

According to an embodiment of the invention, the vent flow path is provided with a one-way valve to allow flow towards the second space section.

According to an embodiment of the invention, the discharge flow path is provided with a one-way valve that allows flow away from the second space section.

According to an embodiment of the invention, the annular gap in the second space section at least partially defines the first space section such that the annular gap and the first space section overlap each other in the direction of the central axis of the cylindrical space. Surround.

According to an embodiment of the invention, the pump is provided with a cylindrical extension coaxial with the first space section forming an annular gap surrounding the piston member, the sleeve member extending with the inner wall of the second space section and the cylindrical extension. Arranged to extend into the annular gap between the parts.

According to an embodiment of the invention, said cylindrical extension is a bushing that is removably attached to said body of said pump.

The present invention is suitable for use as a high pressure pump in a common rail fuel system.

Exemplary embodiments of the invention presented in this patent application should not be construed as limiting the applicability of the appended claims. The verb “comprises” is used as an open restriction that does not exclude the presence of features that are not also presented in this patent application. The features set forth in the dependent claims may be freely combined with each other unless otherwise specified. New features contemplated as features of the invention are set forth in particular in the appended claims.

In the following, the invention will be described with reference to the accompanying exemplary schematic drawings.

1 shows a fuel pump unit according to an embodiment of the invention.
2 shows a fuel pump according to another embodiment of the invention.
3 shows a fuel pump according to a further alternative embodiment of the invention.
4 shows a fuel pump according to a further alternative embodiment of the invention.

1 schematically shows a fuel pump 10 configured to supply fuel to an internal combustion piston engine. More specifically, the pump is a high pressure pump configured to carry fuel at a pressure above 200 MPa. The pump 10 is provided with a supply rail 12 and a high pressure rail 14, wherein both the supply rail 12 and the high pressure rail 14 are first pumps arranged in the body 18 of the pump 10. Is connected to the chamber 16. The body 18 including the pump chamber 16 may also be referred to as a barrel of the pump 10. The supply rail 12 is connected to the pump chamber 16 via the intake conduit 20. The high pressure rail is connected to the pump chamber 16 via an outlet conduit 22. Intake conduit 20 is provided with a one-way valve 24 configured to allow fuel to flow only from feed rail 12 to pump chamber 16. Each outlet conduit 22 is provided with a one-way valve 26 configured to allow fuel to flow only from the pump chamber 16 to the high pressure rail 14. In the embodiment shown in FIG. 1, the supply rail 12 and the high pressure rail 14 are integrated into the body 18, but it is conceivable that the rails are outside the body 18.

The pump 10 is also provided with a piston member 28 arranged into a cylindrical space 30 arranged into the body 18. The cylindrical space 30 has a central axis 32, and the cylindrical space 30 is substantially rotationally symmetric about the central axis 32. Therefore, the piston member 28 is also rotationally symmetric about the central axis 32. The external shape of the body may be designed as needed. The piston member 28 is arranged into space in a reciprocating manner. The piston member 28 has a first end 28 ′ that abuts a cylindrical space 30 that forms a first pumping chamber 16 at its end. The piston also has a second end 28 ″ opposite the first end 28 ′. The piston member 28 is configured to reciprocate and pump fuel in the space 30 provided for the piston member 28. The reciprocating movement of the piston member with the one-way valves 24, 26 in this manner provides the pumping effect of the fuel pump. The piston member 28 is advantageously an assembly of several parts, where it is shown so that the first end 28 ′ and the second end 28 ″ are separate parts removably connected to each other.

Cylindrical space 30 comprises a first space section 30 'having a first diameter D1. In the first space section 30 ′, the wall of the space section and the wall of the piston member 28 are arranged with respect to each other to provide a first sealing gap 34 between the walls, which is also a piston in the body 18. Guide member 28. In addition, the wall of the first space section guides the piston member in the body 18 while it reciprocates in the space. The piston member 28 includes a first portion arranged in the first space section 30 'and also has a diameter substantially the same as the first diameter so as to provide the desired guidance and sealing.

The cylindrical space 30 also includes a second space section 30 ″ having a second diameter D2 larger than the first diameter D1. The second space section 30 ″ is on the same central axis as the first space section 30 ′. The piston member 28 includes a second portion arranged in the second space section 30 ″ to provide the desired guidance and sealing. In the second space section 30 ″, the wall of the second space section and the wall of the piston member 28 are arranged relative to each other to provide a second sealing gap 35 between the walls, respectively. In addition, the wall of the second space section guides the piston member in the second portion within the body 18 while the piston member reciprocates in the space.

There is a second pump chamber 16 ′ arranged in the body 18 of the pump 10. The second pump chamber 16 ′ is coupled with the second space section 30 ″ such that the second pump chamber 16 ′ is configured to use the empty space of the second space section 30 ″ as the pump chamber. Are arranged. The piston member 28 is arranged to be in contact with both the first pump chamber 16 and the second pump chamber 16 ′.

The piston member 28 and the first pump chamber and the second pump chamber are operated in the same manner, that is, in a manner that increases or decreases the volume of the first pump chamber and the second pump chamber while the piston member moves in one direction. It is configured in the pump shown in FIG. 1 to be modified.

As described above, in the first space section 30 ′, the wall of the space section and the wall of the piston member 28 are arranged relative to each other to provide a first sealing gap 34 between the walls. The first sealing gap 34 separates the first pump chamber 16 and the second pump chamber 16 ', which is of annular form. Since the first pump chamber 16 operates as a high pressure pump configured to deliver fuel at a pressure above 200 MPa, the fuel in the first pump chamber tends to flow into the first sealing gap 34 and furthermore the sealing gap There is a tendency to flow through 34. Although not shown here, the first sealing gap 34 between the pump chambers 16, 16 ′ is for collecting fuel material flowing from the first pump chamber 16 into the first sealing gap 34. Means may be provided. Such means may comprise grooves arranged in the walls of the first space section provided with conduits for guiding the fuel material to further processing. Since the second pump chamber 16 ′ is in the second space section 30 ″, it may be referred to generally below.

The pump 10 is provided with means for transferring fuel material away from the second pump chamber 16 ′. Therefore, the pump 10 is first provided with a vent flow path 36. The vent flow path 36 connects the second pump chamber 16, which extends through the body 18 of the pump and is formed into the second space section 30 ″, to the outside of the body 18. The vent flow path 36 is configured to allow gas inflow into the second space section 30 ″ driven by the reciprocating motion of the piston member. The pump 10 further contains fuel material introduced into the second pump chamber 16 ′ or the second space section 30 ″ via the sealing gap 34, ie, the second space section 30 ″ A discharge flow path 38 is provided that connects the second pump chamber 16 'configured to be transported away from the two pump chambers 16' to the outside of the body 18.

The vent flow path 36 is provided with a one-way valve 40 that permits gas flow in the vent flow path 36 in the direction towards the second space section 30 ″ and also prevents backflow of the fluid. The vent flow path 36 has an inlet that opens around the pump 10. Each discharge flow path 38 is provided with a one-way valve 42 configured to allow flow away from the second space section 30 ″ through the discharge flow path 38. During the compression stroke the volume of the second pump chamber 16 'is reduced, thereby pressing it. Gas and liquid in the second pump chamber 16 ′ are forced out from the second pump chamber 16 ′ via the discharge one-way valve 42. In addition, during the suction stroke of the pump, the second pump chamber 16 'expands to cause suction through the venting one-way valve 40.

In FIG. 1, the piston member 28 is in a first extreme position where the first pump chamber 16 has its minimum volume. The piston member 28 is movable by an external force, indicated by arrow 44, which may be provided directly by the operation of the engine.

The piston member 28 is provided with a sleeve member 46 which is connected to the second end 28 ″ of the piston member 28 and which has a closed end, ie a bottom 58. The bottom 58 of the sleeve member 46 extends radially into the piston member 28. The sleeve member 46 may be integral to or separate from the second end 28 ″ of the sleeve member 46 and / or the piston member 28. The bottom 58 of the sleeve member 46 is therefore common with the piston member 28, which serves to receive the force necessary to reciprocate the piston member 28 in the pump 10. The sleeve member is arranged such that an annular space is provided between the sleeve member 46 and the piston member 28, which from now on form a second pump space 16 ′. The sleeve member 46 opens towards the first end 28 ′ of the piston member 28. The sleeve member is introduced into the second space section 30 '' such that the radially inner wall of the second space section 30 '' and the radially inner wall of the sleeve member 46 face each other to provide a second sealing gap 35. Are arranged. The wall of the second space section 30 ″ guides the sleeve member 46 of the piston member 28 within the body 18 as the piston member 28 and the sleeve member move along the central axis 32. .

The body 18 of the pump 10 is provided with a cylindrical extension 48 facing the second end of the piston member 28, which extension is coaxial with the first space section 30 ′. The cylindrical extension 48 has an axial length in the direction of the central axis 32 and an outer diameter smaller than the second diameter D2. The cylindrical extension 48 extends axially into the second space section 30 ″. In this way, the cylindrical extension 48 forms an annular gap 47 in the radial direction between the cylindrical extension 48 of the body and the inner wall of the body. The annular gap 47 at least partially defines the first space section such that the annular gaps of the second space section 30 '' and the first space 30 'section overlap each other in the direction of the central axis 32 of the cylindrical space. Surround. Sleeve member 46 is arranged to extend into the annular gap 47. The end face of the cylindrical extension 48 abuts the second pump chamber 16 ′ together with the piston member 28 and the sleeve member 46. The fitting of the sleeve member 46 extending into the annular gap between the cylindrical extension 48 and the second space section 30 '' is the radial inner wall of the annular gap, ie the cylindrical outer wall of the extension 48 and the sleeve The radially inner walls of the member 46 are adapted to provide a third sealing gap 37 opposite each other.

There is a third space section 60 arranged in a radially annular gap between the inner wall of the body and the cylindrical extension 48, and a sleeve member 49 in contact with the third space section. The third space section is used for the purpose of lubrication of the pump 10. The pump 10 is provided with a lubricant supply channel 62 and a lubricant discharge channel 64. The minimum volume of the third space section 60, and the position and volume of the lubricant supply channel 62 and the lubricant discharge channel 64 are configured to allow the formation of a pond of lubricant in the third space section, but with lubricant 3 Prevent full charge of the space section. In particular, the lubricating oil supply channel 62 and the lubricating oil discharge chamber 64 are dimensioned such that the flow rate of the lubricating oil exiting from the third space section 60 is at least greater than the flow rate of the lubricating oil to the third space section 60 eventually. do.

The vent flow path 36 extends through the body 18 to the inner wall of the second space section 30 ″ in which the outlet 50 is arranged. The vent flow path 36 continues in the sleeve member 46, which opens through the outlet 52 of the vent flow path into the second pump chamber 16 ′. The transition region between the body 18 and the vent flow path 36 in the sleeve member 46 is provided with a rectangular space 54 extending in the direction of the central axis 32, with the vent flow path open. . In this way, the flow path is open at all operating positions of the piston member 28 and the sleeve member 46. The aeration flow path and the exhaust flow path may be realized by providing bores, grooves or otherwise provided channels suitable for the material of the pump 10. In the embodiment of FIG. 1, the rectangular space 54 is provided as an indentation to the outer wall of the sleeve member 46, but it is also conceivable to arrange it with the inner wall of the body 18. The discharge flow path 38 is provided with a similar rectangular space 54 to cause a flow connection between the piston member 28 and the discharge flow path 38 in the body 18.

Now, when installed in an internal combustion engine, an external force 44 is advantageously caused by the engine's power system. Therefore, the piston member 28 is typically indirectly in mechanical force transmission connection with the crankshaft of the engine. In practice, this means that the mechanical force transmission is lubricated by the engine lubricant. The pump 10 is provided with means for conveying the fuel material away from the second pump chamber 16 'and any fuel material exiting through the sealing gap 34 will not enter the engine's lubricating oil.

In FIG. 2, the pumping effect in the second pump chamber 16 ′ is provided with one-way valves by inlets and outlets of the suitably positioned vent flow path 36 and outlet flow path 38 to the piston member and the body. An embodiment of the invention is shown which is achieved without. The rectangular spaces 54 are positioned such that the vent flow path 36 opens when the piston portion is in the suction stroke capable of balancing the underpressure formed in the second pump chamber 16 ′. The inlets and outlets of the vent flow path 36 and the outlet flow path 38 are closed when the piston member moves toward the first end 28 'and the pressure in the second pump chamber 16' is closed. Is arranged to increase in. At a specific position of the piston member 28, the discharge flow path 38 is open and the second pump chamber is discharged.

In FIG. 3, a pump unit 10 is shown in which the structure of the second pump chamber 16 ′ is different from that shown in FIGS. 1 and 2. Here, the piston member 28 extends from the first end to the cam drive system (not shown) of the pump 10 via the guide flange 56. The piston member 28 is provided with a bottom 58 as a radial extension in contact with the second pump chamber 16 ′. In this case, there is no sleeve member 46 provided in relation to the bottom 58. The radial distal end of the bottom 58 is suitably sealed against the inner wall of the second space section 30 ″ so that the pumping effect can be obtained by the second pump space 16 ′. A feature common to both FIGS. 1 to 3 is that the discharge flow path 38 opens to the part in contact with the second pump chamber 16 ′ furthest from the first end of the piston member. When the pump is in the same position as that shown in Figs. 1 to 2 (center axis 32 is positioned vertically, and the first end 28 'of the piston member is oriented upwards), the discharge flow path ( 38 opens to the lowest position in the second pump chamber 16 '. In practice, the central axis 32 need not be exactly vertical, but the pump may be tilted as long as the discharge flow path is arranged at the substantially lowest position into the second pump chamber 16 '.

In FIG. 4, the pump 10 is configured for installation so that the first end 28 ′ of the piston member 28 is horizontal below the second end 28 ″ of the piston member 28. An embodiment is shown. The basic configuration of the pump 10 is similar to that shown in FIG. 1, but these features that are affected by the starting orientation are designed differently. In FIG. 4, it is shown that the first scraping gap 34 is provided with a fuel scraper ring 68 in an annular space arranged to minimize the flow of fuel to the second space section 30 ″. There is also another annular space 67 proximate to the first pump chamber 16 where the fuel discharge channel 66 extends out of the body 18. Although not shown, a similar fuel scraper ring 68 and fuel discharge channel 66 may be arranged in the pumps shown in FIGS. This arrangement reduces the amount of fuel flow through the first sealing gap 34 into the second pump space 16 ′, but the fuel destined for the fuel discharge channel 66 is still quite high pressure.

In the pump 10 shown in FIG. 4, the second space section 30 ″ is provided with a bushing 70. The bushing is a generally cylindrical portion with an outwardly extending shoulder at its first end. It is attached to the inner surface of the second space section 30 '' at the first end, and here also an annular space 60 is provided between the bushing 70 and the inner surface of the second space section 30 ''. A section having a diameter as small as that of the second space section 30 '' is provided. The bushing 70 is attached to the body 18 at the side of the first end 28 ′ of the piston member 28 at its first end. The piston member 28 includes a sleeve member 46 that is provided in the second space section 30 ″ so that the desired guide and seal are provided to correspond to FIGS. 1 and 2. In the second space section 30 ″, the inner wall of the second space section and the wall of the sleeve member 46 are arranged relative to each other to provide a second sealing gap 35 between the walls, respectively. The sleeve member 46 is arranged to extend into the annular gap 60 formed by the wall of the second space section 30 ″ and the bushing 70. In this way, the bushing 70 abuts the second pump chamber 16 ′ together with the sleeve member 46 and the piston member 28. The fitting of the sleeve member 46 extending into the annular gap between the bushing 70 and the wall of the second space section 30 ″ is the radial inner wall of the annular gap, ie the radial outer wall of the bushing 70 and the sleeve The radially inner walls of the member 46 are adapted to provide a third sealing gap 37 opposite each other.

In FIG. 4 there is a third space section 60 arranged in a radially annular gap between the inner wall of the body and the bushing 70, and a sleeve member 49 in contact with the third space section 60. The third space section 60 is used for the purpose of lubrication of the pump 10. The pump 10 is provided with a lubricant supply channel 62 and a lubricant discharge channel 64. The lubricating oil supply channel 62 is arranged at a position for supplying oil to the second sealing gap 35. The lubricant discharge channel 64 is arranged to open into the third space section 60.

The pump 10 is provided with means for transferring fuel material away from the second pump chamber 16 ′. Therefore, the pump 10 is first provided with a vent flow path 36. The vent flow path 36 extends through the body 18 of the pump and connects the second pump chamber 16, which is formed into the second space section 30 ″, with the outside of the body 18. The vent flow path 36 is configured to allow gas inflow into the second space section 30 ″ driven by the reciprocating motion of the piston member 28. The pump 10 further connects a second pump chamber 16 ′ to the outside of the body 18 to seal fuel material introduced into the second pump chamber 16 ′ or second space section 30 ″. A discharge flow path 38 is provided that is configured to convey away from the second space section 30 ″, ie the second pump chamber 16 ′, through the gap 34.

The vent flow path 36 is provided with a one-way valve 40 that allows gas flow in the vent flow path 36 in the direction towards the second space section 30 ″ and also prevents backflow of the fluid. The vent flow path 36 has an inlet that opens around the pump 10. Each discharge flow path 38 is provided with a one-way valve 42 configured to allow flow away from the second space section 30 ″ through the discharge flow path 38. During the compression stroke, the volume of the second pump chamber 16 'is reduced and thereby pressurized. Gas and liquid in the second pump chamber 16 ′ are forced out from the second pump chamber 16 ′ via the discharge one-way valve 42. During the suction stroke of the pump, the second pump chamber 16 'also expands to cause suction through the venting one-way valve 40.

The sealing effect of the aforementioned sealing gaps may be based on the surface and / or dimensional tolerances of the parts and / or the quality of the separate sealing elements, such as o-rings or lip seals.

While the invention has been described herein in the manner of an example in connection with what is presently considered to be the most preferred embodiments, the invention is not limited to the disclosed embodiments, but as defined in the appended claims, features of the invention Should be understood to include various combinations or modifications of the above, and several other applications included within the scope of the present invention. The detailed description referred to in connection with any of the above embodiments may be used in conjunction with other embodiments in which this combination is technically possible.

Claims (7)

As a fuel pump 10 for supplying fuel to an internal combustion piston engine,
A cylindrical space 30 arranged in the body 18 and having a central axis 32,
Piston member 28 arranged to reciprocate in said cylindrical space 30
Including,
The cylindrical space 30 includes a first space section 30 ′ having a first diameter D1, the wall of the cylindrical space 30 delimiting the piston member 28 in the body 18. The wall of the cylindrical space and the wall of the piston member 28 are arranged relative to each other to guide to provide a first sealing gap 34, and
The first space section 30 ′ forms the first pumping chamber 16 of the fuel pump 10 that is configured to pump fuel as the piston member 28 reciprocates in the cylindrical space. The central axis 32, bounded by a first end 28 ′ of the piston member 28, wherein the cylindrical space 30 has a second diameter D2 greater than the first diameter D1. Further includes a second space section 30 '' on top,
The piston member is provided with a sleeve member 46 extending toward the first end 28 ′ of the piston member 28 such that an annular space is provided between the sleeve member 46 and the piston member 28. And the annular space opens towards the first end 28 ′ of the piston member 28, and an inner wall of the second space section 30 ′ is in the second space section 30 ″. The inner wall of the second space section 30 ″ and the radial outer wall of the sleeve member 46 are arranged relative to each other to guide the sleeve member 46 at , And
The annular third space section 60 is arranged into the fuel pump 10, and the third space section 60 is arranged to extend into the annular third space section 60. And partially bounded by an inner wall of the second space section 30 '', and
A fuel pump, to which the lubricant supply channel (62) and the lubricant discharge channel (64) are connected to the third space section (60). The method of claim 1,
The pump 10 is provided with a cylindrical extension 48 coaxial with the first space section 30 ′ forming an annular gap surrounding the piston member 28, wherein the sleeve member 46 is provided with the sleeve. A fuel pump, which is arranged to extend into an annular gap between the inner wall of the two space section (30 '') and the cylindrical extension (48). The method of claim 1,
In the second space section 30 ″ of the pump configured to pump fuel from the second space section 30 ″ as the piston member 28 reciprocates in the space 30. A second pumping chamber 16 ′ is provided, the pump 10 of which is adapted to allow gas inflow into the second space section 30 ″, driven by the reciprocating motion of the piston member. A vent flow path 36 connecting the second space section 30 " to the outside, and the second to the outside of the body for conveying fuel material away from the second space section 30 " A fuel pump, which is characterized in that an exhaust flow path 38 is provided which connects the space section 30 ''. The method of claim 3, wherein
The fuel pump, characterized in that the vent flow path (36) is provided with a one-way valve (40) to allow flow towards the second space section (30 ''). The method of claim 3, wherein
The fuel pump, characterized in that the discharge flow path is provided with a one-way valve (42) to allow flow away from the second space section (30 ''). The method of claim 1,
The annular gap in the second space section 30 '' is at least partially such that the annular gap and the first space section 30 'overlap each other in the direction of the central axis 32 of the cylindrical space. A fuel pump, characterized by surrounding one space section. The method of claim 2,
The fuel pump (10), characterized in that the cylindrical extension (48) is a bushing (70) which is removably attached to the body (18) of the pump (10).

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