JP2003049743A - Fuel pump for fuel system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel pump having the longest service life possible. SOLUTION: At least one end surface 64 or 65 of an insert 40 is prescribed and oriented with relation to size in such a way that a step part 46 in the insert 40 is loaded inward toward a ring shoulder part 44 in the axial direction by hydraulic pressure generated during operation. A material deformation part 52 comprising plastic material acts on the insert 40 only inward in the axial direction, so that load on the material deformation part 52 is reduced by the hydraulic pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump for a fuel system of an internal combustion engine, which has a casing, at least one piston, a driving means for driving the piston, and an insert for guiding the piston therein. A body and a notch extending inwardly in the casing, the notch having an insert received therein, the notch having a ring shoulder for obliquely descending; The step portion of the insert having a shape complementary to the ring shoulder portion is in contact with the ring shoulder portion, and the casing is provided with the plastic material deforming portion, and the material deforming portion It relates to a type in which the step of the insert is kept in contact with the ring shoulder.

[0002]

PRIOR ART German Patent Publication No. 19747
In the known piston pump based on 851,
The piston is guided in the cylinder liner.
The cylinder liner is further inserted into a stepped hole provided in the casing. The bottom of the cylinder liner is supported by the inclined portion having a shape complementary to the hole in the casing via the inclined portion. The hole in the casing is closed outward by a cylindrical closure plug.
The closing plug loads the cylinder liner toward the inclined portion of the casing and is retained in the casing by the caulking portion so as not to be disengaged.

However, during operation of known piston pumps it has been found that the following cannot always be ruled out: the press fit between the cylinder liner and the casing loosening over time.
When such sagging occurs, it causes unwanted noise, unwanted leaks and, in the worst case, complete malfunction of the piston pump.

[0004]

SUMMARY OF THE INVENTION The object of the invention is therefore to improve a fuel pump of the type mentioned at the outset to provide a fuel pump having a service life which is as long as possible.

[0005]

In order to solve this problem, in the arrangement according to the invention, at least one end face of the insert is dimensionally fitted (groessenmaessig) as follows:
That is, the plastic material deformation is defined and oriented such that the step of the insert is axially loaded inward in the axial direction towards the ring shoulder by the hydraulic pressure generated during operation. And acts on the insert only inwardly, so that the material deformation is lightened by the hydraulic pressure.

[0006]

The fuel pump according to the present invention has the following advantages. That is, in the fuel pump according to the invention, the plastic material deformation which keeps the insert in its optimum operating position is not exposed to additional loads during operation. And in the most advantageous case, the function of the plastic material deformation can be limited to preventing the insertion body from coming out of the notch. In such a case, only a very small force acts on the deformed part of the plastic material, so that re-deformation that causes looseness of the insert (Rueckverformung)
There is no fear of.

[0007] The insert body is cooperated with the ring shoulder portion that obliquely descends based on the hydraulic pressure that loads the insert body inward in the axial direction and the step portion having a shape complementary to the ring shoulder portion. Will have a self-centering function continuously and constantly within the notch. Therefore, the insert always occupies the optimum position where wear and noise are minimized. The arrangement according to the invention increases the service life of the fuel pump as a whole.

Further advantageous configurations of the fuel pump according to the invention as claimed in claim 1 are set forth in claim 2 and the following claims.

For example, in another configuration of the present invention, the plastic material deforming portion has a caulking portion and / or an edge bending portion.
Such a material deformation portion can be easily formed.
The characteristic important to the invention that the material deformation acts only axially inward on the insert is also easily achievable in the crimp and / or edge bends.

In a particularly advantageous design of the fuel pump according to the invention, the angle between the conical ring surface of the ring shoulder of the casing or of the step of the insert and the longitudinal axis of the notch is 30. Less than or equal to 30 °, so that a self-locking effect occurs between the casing and the insert. Thus, such an angular range additionally prevents the insert from loosening from the notch in the casing. This also reduces the load on the plastic material deformation.

In yet another particularly advantageous configuration of the invention:
The casing is made of aluminum and the insert is made of steel. In particular, aluminum tends to deform to some extent under load in the long term. And this kind of deformation, called "Kriechen," at least partially affects the plastic material deformation,
This can cause the insert to relax.

However, as in the fuel pump according to the invention, when the plastic material deformation is lightened by hydraulic pressure, no or little creep or deformation occurs, which in turn increases the service life of the fuel pump. At the same time, the weight of the fuel pump is also relatively low due to the aluminum casing, which is advantageous for the area of use of the fuel pump.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

The fuel system generally designated by the numeral 10 in FIG. 1 has a fuel tank 12, from which an electric fuel pump 14 carries fuel 16. A fuel conduit 18 leads from the electric fuel pump 14 to a high pressure fuel pump 20. This high-pressure fuel pump 20
Is driven directly by the camshaft of the internal combustion engine 30 in a manner not shown.

The high pressure fuel pump 20 pumps fuel to a fuel assembly conduit 24 via a fuel conduit 22. A plurality of injection valves 26 are connected to the fuel collecting conduit 24, and these injection valves 26 inject fuel directly into the fuel chamber 28 of the internal combustion engine 30. High-pressure fuel pump 20 to fuel assembly conduit 22
The amount of fuel pumped to is adjusted by a fuel amount control valve 32 which is a part of the high-pressure fuel pump 20.

The range of the high-pressure fuel pump 20 is shown in detail in FIG. As can be seen from FIG. 2, the high-pressure fuel pump 20 has a casing 34, which is flange-connected to a casing 36 of the internal combustion engine 30. A stepped notch 38 is provided in the casing 34 so as to penetrate the entire casing 34. An insert 40 is inserted in this notch 38, which insert 40 in the illustrated embodiment is a cylinder liner for a piston 42.

The notch 38 tapers at approximately half its height towards the casing 36 of the internal combustion engine 30 via a ring shoulder 44 which descends diagonally. A step portion 46 having a shape complementary to the ring shoulder portion 44 is provided on the outer peripheral surface of the cylinder liner 40, and the step portion 46 is in contact with the ring shoulder portion 44. This causes the insert 40 to be centered with respect to the casing 34. The piston 42 is received in the cylinder liner 40 in a stepped through hole 48.

An annular step portion 50 is provided on the upper edge of the cylinder liner 40, and the plastic material deforming portion 52 provided on the casing 34 is pushed into the step portion 50. The deforming portion 52 simply loads the cylinder liner 40 inward in the axial direction. The plastic material deforming portion 52 is, for example, a caulking portion or an edge bending portion. The plastic material deforming portion 52 holds the cylinder liner 40 in a predetermined position in the notch 38 of the casing 34, that is, a position where the step portion 46 is in contact with the ring shoulder portion 44.

The notch 38 in the casing 34 of the high-pressure fuel pump 20 is closed outward by the quantity control valve 32. The region 54 of the quantity control valve 32 projects into the upper region of the through hole 48 in the cylinder liner 40 and is sealed by the O-ring 56 with respect to this upper region. A working chamber 58 is formed between the region 54 of the quantity control valve 32, the cylinder liner 40 and the piston 52. The working chamber 58 is connected on the inlet side to the fuel conduit 18 via a check valve (not shown) in a manner not shown. The working chamber 58 is connected to the fuel conduit 22 on the outlet side via a passage 60 and a check valve 62.

The through hole 48 is formed as follows, that is, the diameter of the working chamber 58 is larger than the diameter of the through hole 48 in the region for guiding the piston 42. With this structure, the ring surface 64 is provided on the cylinder liner 40 toward the working chamber 58.
Another ring surface 65 exists above the original working chamber 58 and immediately below the region 54 of the quantity control valve 32.
The meaning of both ring surfaces 64, 65 will be described in more detail below.

The piston 42 is driven by a drive cam 68 via a dish tappet 66. That is, the piston 42 is axially loaded by the rotation of the shaft 70 and here by the drive cam 68 connected to the shaft 70. In this case, the piston 42 is a dish tappet 66, and the compression spring 7
It is pressed toward the drive cam 68 by 2. The drive shaft 70 of the high-pressure piston pump 20 is rotatably supported with low friction through a ball bearing not shown in FIG.
The drive shaft together with the ball bearing is the casing 36 of the internal combustion engine 30.
It is located inside. Drive cam 68 and dish-shaped tappet 66
Lubrication of the contact surface and the ball bearing between and is performed by lubricating oil (not shown in FIG. 2).

The casing 34 of the high pressure fuel pump 20 is
Made of aluminum, for which the cylinder liner 4
0 is manufactured from steel.

The high pressure fuel pump 20 operates as follows: As the drive shaft 70 and drive cam 68 rotate, the piston 42 is axially reciprocated. This causes the working chamber 58 to be alternately filled with fuel and the fuel 16 is then pumped by the piston 42 from the working chamber 58 through the passage 60 and the check valve 62 into the fuel conduit 22 and further into the fuel assembly conduit 24. To be done.

When the piston 42 moves upward as seen in FIG. 2, the fuel existing in the working chamber 58 is compressed. As a result, the pressure rises in the work chamber 58. This increase in pressure also acts on both ring surfaces 64, 65 of the cylinder liner 40. As a result, a resultant force by hydraulic pressure is generated, and this hydraulic pressure axially loads the step portion 46 of the cylinder liner 40 toward the ring shoulder portion 44. At the same time, due to this load, the plastic material deformation part 5
2 is reduced.

The conical ring surface of the ring shoulder 44 of the casing 34 or the stepped portion 46 of the cylinder liner 40 and the longitudinal axis 74 of the notch 38.
The angle between and is approximately 25 ° in the illustrated embodiment. This angle causes a self-locking effect between the casing 34 and the cylinder liner 40. As a result, even when high pressure does not exist in the working chamber 58, for example, during the pressure-feeding stroke of the high-pressure fuel pump 20, the cylinder liner 40 causes the casing 34 to move.
It is possible to reliably prevent the disengagement from the press fitting in the.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a fuel system of an internal combustion engine equipped with a fuel pump.

2 is an enlarged cross-sectional view showing a part of the fuel pump shown in FIG.

[Explanation of symbols]

10 fuel system, 12 fuel tank, 14 fuel pump, 16 fuel, 18 fuel conduit, 20 high pressure fuel pump, 22 fuel conduit, 24 fuel assembly conduit,
26 injection valve, 28 combustion chamber, 30 internal combustion engine,
32 fuel amount control valve, 34 casing, 36 casing, 38 notch, 40 insert body, 42 piston, 44 ring shoulder portion, 46 step portion, 48
Through hole, 50 steps, 52 Material deformation part, 54
Area, 58 working chamber, 60 passage, 62 check valve, 64, 65 ring surface, 66 plate type tappet,
68 drive cam, 70 shaft, 72 compression spring, 7
4 Longitudinal axis

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Peter Loperz             Federal Republic of Germany Oberlique Singe             Primerveke 7 F term (reference) 3G066 AA02 AB02 AC09 AD02 BA46                       BA48 CA08 CA09 CE02

Claims (4)

[Claims] 1. A fuel pump (20) for a fuel system (10) of an internal combustion engine (30) comprising a casing (34), at least one piston (42), and the piston (4).
Drive means (70) for driving 2), an insert (40) for guiding the piston (42) therein, and a notch (38) extending inwardly in the casing (34). And an insert (40) is received in the notch (38), the notch (38) having a diagonally descending ring shoulder (44). The step (46) of the insert (40) having a shape complementary to the ring shoulder (44) is in contact with the part (44), and the plastic material deforming part (52) is attached to the casing (34). ) Are provided, the step (46) of the insert (40) being made into a ring shoulder (4) by the material deformation (52).
8) at least one end face (64, 65) of the insert (40) is dimensioned to provide the following: insert (40).
Of the material of the plastic material is defined and oriented such that the step (46) of the shaft is axially loaded inward in the axial direction towards the ring shoulder (44) by the hydraulic pressure generated during operation. (52) acts axially only inwardly on the insert (40), which causes the material deformation (5)
2. A fuel pump for a fuel system of an internal combustion engine, characterized in that the load is reduced by the hydraulic pressure. 2. The fuel pump according to claim 1, wherein the plastic material deforming portion (52) has a caulking portion and / or an edge bending portion. 3. A conical ring surface of a ring shoulder (44) in a casing (34) or a step (46) in an insert (40) and a longitudinal axis (74) of a notch (38). 3. The angle according to claim 1 or 2, wherein the angle between and is less than or equal to 30 °, resulting in a self-locking effect between the casing (34) and the insert (40). Fuel pump. 4. The fuel pump according to claim 1, wherein the casing (34) is made of aluminum and the insert (40) is made of steel.