Filter for piston type high-pressure fuel pump

Details Filter for piston type high-pressure fuel pump Filter for piston type high-pressure fuel pump

1998-08-04

2001-02-20

Walberg, Teresa (Department: 3742)

Pumps

Combined

Reexamination Certificate

active

06190139

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a filter provided at a fuel intake of a piston type high-pressure fuel pump and, more particularly, to a filter for a piston type high-pressure fuel pump which does not clog up from freezing.
2. Description of the Related Art
Diesel engines have been widely known as the type of internal-combustion engines called “cylinder injection internal-combustion engines” or “direct injection internal-combustion engines” wherein fuel is injected in engine cylinders. In recent years, the cylinder injection type has been proposed also for spark ignition engines or gasoline engines. There is a tendency in such a cylinder injection internal-combustion engine to increase fuel injection pressure to produce particulate fuel spray to shorten the fuel injection period in order to achieve higher performance of the engine and to reduce emission gas. An engine provided with a supercharger requires a high fuel injection pressure to match charging pressure at the time of supercharging. For this reason, the fuel supply system in the gasoline cylinder direct injection internal-combustion engine is adapted to provide a sufficiently high fuel injection pressure of, for example, about 10 atm.
FIG. 7
is a schematic block diagram showing a conventional fuel supply system. In
FIG. 7
, a delivery pipe
1
has as many injectors
1
a
as the cylinders of a gasoline cylinder direct injection internal-combustion engine, which is not shown. A high-pressure fuel pump
100
is disposed between the delivery pipe
1
and a fuel tank
2
, the delivery pipe
1
and the high-pressure fuel pump
100
being connected by a high-pressure fuel pipe
3
. The high-pressure fuel pump
100
and the fuel tank
2
are connected by a low-pressure fuel pipe
4
serving as a fuel intake route. The low-pressure fuel pipe
4
located upstream from the high-pressure fuel pump
100
is provided with a filter
5
. A drain
6
of the high-pressure fuel pump
100
is routed back to the fuel tank
2
.
The low-pressure fuel pipe
4
is provided with an in-tank, low-pressure fuel pump
7
at the end thereof on the fuel tank
2
side. A filter
8
is provided at the fuel intake of the low-pressure fuel pump
7
. The low-pressure fuel pipe
4
is further provided with a low-pressure regulator
10
located between the high-pressure fuel pump
100
and the low-pressure fuel pump
7
. A drain
11
of the low-pressure regulator
10
is routed back to the fuel tank
2
.
The delivery pipe
1
also has a high-pressure fuel passage
12
at the opposite end from the high-pressure fuel pump
100
. The high-pressure fuel passage
12
is provided with a high-pressure regulator
14
, a drain
21
of the high-pressure regulator
14
being routed back to the fuel tank
2
.
In such a fuel supply system having the constitution described above, the fuel is pressurized to a certain degree by the low-pressure fuel pump
7
and further pressurized by the high-pressure fuel pump
100
before reaching the delivery pipe
1
, then it is injected through the injector
1
a into an engine cylinder, which is not shown. At this time, the discharge pressure from the low-pressure fuel pump
7
is stabilized by the low-pressure regulator
10
such that it stays within a predetermined range, and the discharge pressure from the high-pressure fuel pump
100
is also stabilized by the high-pressure regulator
14
such that it stays within a predetermined range. The fuel supplied to the high-pressure fuel pump
100
is filtered through the filter
5
to prevent foreign matter in the fuel from entering the high-pressure fuel pump
100
. A plurality of the mesh openings of the conventional filter
5
have been formed so that one side of each square mesh opening measures 30 &mgr;m.
In the fuel supply system having the constitution described above, since each of the openings of the filter
5
provided at the upstream of the high-pressure fuel pump
100
is formed into a rectangle, one side of which measuring 30 &mgr;m, the filter has been clogged up from time to time by frozen moisture in fuel or gasoline.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made with a view toward solving the problem described above, and it is an object thereof to provide a filter for a piston type high-pressure fuel pump which does not clog up from freezing under adverse operating conditions.
To this end, according to the present invention, there is provided a filter for a piston type high-pressure fuel pump, which filter is provided in a fuel intake passage of the piston type high-pressure fuel pump. The filter has many square openings, and one side of each opening measures 50 &mgr;m to 200 &mgr;m.
In a preferred form of the filter for a piston type high-pressure fuel pump, one side of each opening measures 50 &mgr;m to 80 &mgr;m.
In another preferred form of the filter for a piston type high-pressure fuel pump, the piston type high-pressure fuel pump supplies fuel to a gasoline cylinder direct injection internal-combustion engine.
In yet another preferred form of the filter for a piston type high-pressure fuel pump, the filter is provided in an intake passage of a piston type high-pressure fuel pump which includes: casing in which the intake passage for taking fuel in and a discharge passage for discharging the fuel are formed; a cylinder formed in the casing; a fuel pressurizing chamber formed in a part of the cylinder; and a plunger disposed in the cylinder so that it may reciprocate; wherein fuel is introduced through the intake passage by the reciprocation of the plunger into the fuel pressurizing chamber where it is pressurized, then the pressurized fuel is discharged through the discharge passage.
In a further preferred form of the filter for a piston type high-pressure fuel pump, the piston type high-pressure fuel pump has a lead valve located between the intake passage and the fuel pressurizing chamber.


REFERENCES:
patent: 4272359 (1981-06-01), Owen
patent: 4410302 (1983-10-01), Chiba et al.
patent: 4438882 (1984-03-01), Frehner
patent: 4859348 (1989-08-01), Jusaitis et al.
patent: 5338368 (1994-08-01), Fletcher et al.
patent: 5832904 (1998-11-01), Morishita et al.
patent: 5904845 (1999-05-01), Girondi
patent: 5971728 (1999-10-01), Konishi et al.
patent: 195 49 108 A1 (1997-07-01), None
patent: 7-077118 (1995-03-01), None
Robert Bosch GmbH: “Kraftfahrtechnisches Taschenbuch” 20thed., Düsseldorf, VDI Verlag, 1987, p. 382.

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