Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-07-20
2002-03-26
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S446000, C123S468000
Reexamination Certificate
active
06360722
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel supply apparatus for supplying fuel to, for example, a direct injection engine.
2. Description of the Related Art
FIG. 5
is a fuel circuit diagram of a conventional fuel supply apparatus;
FIG. 6
is a partially cut away general sectional view of a first high-pressure fuel supply assembly
100
A shown in
FIG. 5
; and
FIG. 7
is a sectional view of a valve assembly shown in FIG.
6
.
The fuel supply apparatus includes: a fuel tank
1
; a low-pressure fuel pump
2
provided in the fuel tank
1
; a low-pressure fuel intake pipe
3
having one end thereof connected to the low-pressure fuel pump
2
and the other end thereof connected to the first high-pressure fuel supply assembly
100
A and a second high-pressure fuel supply assembly
100
B; a low-pressure regulator
4
branched from the low-pressure fuel intake pipe
3
and which sets a low-pressure fuel to a constant pressure; a first branch pipe
50
A and a second branch pipe
50
B having their one end connected to the other end of the low-pressure fuel intake pipe
3
;
the first high-pressure fuel supply assembly
100
A connected to the other end of the first branch pipe
50
A; the second high-pressure fuel supply assembly
100
B connected to the other end of the second branch pipe
50
B; and a drainage pipe
17
connecting the first high-pressure fuel supply assembly
100
A and the second high-pressure fuel supply assembly
100
B to the fuel tank
1
. Reference numeral
12
denotes a filter.
The first high-pressure fuel supply assembly
100
A includes: a low-pressure damper
5
provided in a low-pressure fuel intake passage
51
and which absorbs surges in a low-pressure fuel; a high-pressure fuel pump
6
that pressurizes the low-pressure fuel from the low-pressure damper
5
and discharges it into a high-pressure fuel discharge passage
7
; a high-pressure damper
8
that absorbs surges in a high-pressure fuel flowing through the high-pressure fuel discharge passage
7
; and a high-pressure regulator
10
disposed in a branch passage
9
branching from the high-pressure fuel discharge passage
7
at a branch portion
18
and which adjusts a high-pressure fuel to a predetermined pressure.
The high-pressure fuel pump
6
includes a valve assembly
20
for opening and closing the low-pressure fuel intake passage
51
and the high-pressure fuel discharge passage
7
, and a high-pressure fuel supply body
21
for pressurizing a low-pressure fuel from the low-pressure fuel intake passage
51
and discharging it into the high-pressure fuel discharge passage
7
.
The valve assembly
20
is constituted by a first plate
22
, a second plate
23
, and a thin-plate valve main body
19
sandwiched between the plates
22
and
23
. A first fuel inlet
24
in communication with the low-pressure fuel intake pipe
3
, and a first fuel outlet
25
which has an inside dimension larger than an inside dimension of the first fuel inlet
24
and which is communication with the high-pressure fuel discharge passage
7
are formed in the first plate
22
. A second fuel inlet
26
having an inside dimension larger than that of the first fuel inlet
24
, and a second fuel outlet
27
having an inside dimension smaller than that of the first fuel outlet
25
are formed in the second plate
23
. The valve main body
19
has an intake-side tongue
28
interposed between the first fuel inlet
24
and the second fuel inlet
26
, and a discharge-side tongue
29
interposed between the first fuel outlet
25
and the second fuel outlet
27
.
The high-pressure fuel supply body
21
includes: a casing
30
that houses the valve assembly
20
in a first recess
30
a
; a cylindrical sleeve
31
housed in surface contact with the second plate
23
of the valve assembly
20
; a piston
33
slidably inserted in the sleeve
31
to form a fuel pressurization chamber
32
in cooperation with the sleeve
31
; and a first spring
36
disposed between a bottom surface
34
of the fuel pressurization chamber
32
and a holder
35
and which urges the piston
33
in a direction for expanding the volume of the fuel pressurization chamber
32
.
The high-pressure fuel supply body
21
further includes: a housing
37
fitted over the sleeve
31
; an annular securing member
38
which is fitted over the housing
37
and threadably attached to the first recess
30
a
of the casing
30
by means of an external thread portion
38
a
formed on an outer circumferential surface thereof, and which presses and secures the valve
20
, the sleeve
31
, and the housing
37
in the first recess
30
a
of the casing
30
; a metal bellows
40
provided between the housing
37
and a receiving portion
39
; a second spring
41
compressed and disposed between the housing
37
and a holder
42
at around an outer periphery of the bellows
40
; and a bracket
43
provided to surround the second spring
41
and secured to the casing
30
by a screw (not shown).
The high-pressure fuel supply body
21
further includes: a tappet
44
slidably disposed in a slide bore
43
a
in an end portion of the bracket
43
; a pin
45
rotatably penetrating the tappet
44
; a bush
46
rotatably fitted to the pin
45
; and a cam roller
47
. A rotational motion of a cam shaft causes the pin
45
, the tappet
44
, and the piston
33
to reciprocate along a profile of the cam
52
.
The high-pressure damper
8
is equipped with a diaphragm (not shown) formed of a stainless-steel thin disc that partitions between a back-pressure chamber (not shown) filled with a high-pressure gas and a buffer chamber (not shown). The diaphragm moves so that a pressure of fuel flowing into the buffer chamber from the high-pressure fuel discharge passage
7
is equalized with a pressure of the high-pressure gas in the back-pressure chamber, thereby changing a volume inside the buffer chamber to absorb surges in the fuel in the high-pressure fuel discharge passage
7
.
The second high-pressure fuel supply assembly
100
B shares the same a structure as that of the first high-pressure fuel supply assembly
100
A. Components of the second high-pressure fuel supply assembly
100
B will be assigned like reference numerals as the components of the first high-pressure fuel supply assembly
100
A, and the descriptions thereof will not be repeated.
In the fuel supply assembly having the configuration set forth above, fuel in the fuel tank
1
flows through the low-pressure fuel intake pipe
3
as the low-pressure fuel pump
2
is driven, and the fuel is branched into the first branch pipe
50
A and the second branch pipe
50
B. The fuel branched into the first branch pipe
50
A is supplied to the first high-pressure fuel supply assembly
100
A, while the fuel branched into the second branch pipe
50
B is supplied to the second high-pressure fuel supply assembly
100
B.
In the first high-pressure fuel supply assembly
10
A, the piston
33
reciprocates via the cam roller
47
, the bush
46
, the pin
45
, and the tappet
44
when the drive cam
52
secured to the cam shaft of an engine rotates.
When the piston
33
descends (during a fuel intake stroke), the volume in the fuel pressurization chamber
32
increases, while the pressure in the fuel pressurization chamber decreases. When the pressure in the fuel pressurization chamber
32
falls below the pressure at the first fuel inlet
24
, the intake-side tongue
28
of the valve main body
19
bends toward the second fuel inlet
26
, allowing fuel in the low-pressure fuel intake passage
51
to flow through the first fuel inlet
24
into the fuel pressurization chamber
32
.
When the piston
33
ascends (during a fuel discharge stroke), the pressure in the fuel pressurization chamber
32
increases, and when the pressure in the fuel pressurization chamber
32
rises above the pressure at the first fuel outlet
25
, the discharge-side tongue
29
of the valve main body
19
bends toward the first fuel outlet
25
, causing the fuel in the fuel pressurization chamber
32
to be fed through the first
Mitsubishi Denki & Kabushiki Kaisha
Moulis Thomas N.
Sughrue & Mion, PLLC
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