Pumps – Expansible chamber type – Having pulsation dampening fluid receiving space
Reexamination Certificate
2000-01-13
2001-07-03
Tyler, Cheryl J. (Department: 3746)
Pumps
Expansible chamber type
Having pulsation dampening fluid receiving space
C417S542000, C138S026000, C138S031000
Reexamination Certificate
active
06254364
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-pressure fuel supply assembly used in a cylinder-injected engine, for example.
2. Description of the Related Art
FIG. 6
is a block diagram showing a construction of a conventional high-pressure fuel supply assembly
100
,
FIG. 7
is a partially removed cross section of the high-pressure fuel supply assembly
100
,
FIG. 8
is a front elevation of the low-pressure damper
5
in
FIG. 7
, and
FIG. 9
is a cross section of the high-pressure regulator
10
in FIG.
7
.
This high-pressure fuel supply assembly
100
includes: a low-pressure damper
5
through which flows low-pressure fuel conveyed by a low-pressure fuel pump
2
within a fuel tank
1
, the low-pressure damper
5
being connected to a low-pressure fuel intake passage
3
; a high-pressure fuel pump
6
for pressurizing low-pressure fuel from the low-pressure damper
5
and discharging it into a high-pressure fuel discharge passage
7
; a high-pressure damper
8
for absorbing surges in the high-pressure fuel flowing through the high-pressure fuel discharge passage
7
; and a high-pressure regulator
10
for adjusting the pressure of the high-pressure fuel to a predetermined pressure, the high-pressure regulator
10
being disposed in a side passage
9
branching from the high-pressure fuel discharge passage
7
.
Moreover, reference numeral
4
is a low-pressure regulator mounted in a passage branching from the low-pressure fuel intake passage
3
, numeral
12
are filters, numeral
13
are check valves, numeral
14
is a drainage passage returning fuel from the high-pressure fuel pump
6
to the fuel tank
1
, numeral
15
are delivery pipes connected to the high-pressure fuel discharge passage
7
, and numeral
16
are fuel injection valves mounted on the delivery pipes
15
.
The above low-pressure damper
5
is mounted in a first recess
50
a
in a casing
50
. The low-pressure damper
5
includes: a cylindrical stainless-steel holder
51
; a stainless-steel base
54
having a ball
53
disposed in a bore
52
; and a stainless-steel bellows
55
disposed inside the holder
51
.
The above high-pressure fuel pump
6
includes: a valve assembly
20
for opening and closing the low-pressure fuel intake passage
3
and the high-pressure fuel discharge passage
7
; and a high-pressure fuel supply body
21
for pressurizing low-pressure fuel and discharging it into the high-pressure fuel discharge passage
7
.
FIG. 10
is a cross section of the valve assembly
20
, the valve assembly
20
being composed of: a first plate
22
; a second plate
23
; and a thin, flat valve main body
19
positioned between the first and second plates
22
and
23
. A first fuel inlet
24
connected to the low-pressure fuel intake passage
3
and a first fuel outlet
25
connected to the high-pressure fuel discharge passage
7
are formed in the first plate
22
, the inside dimensions of the first fuel outlet
25
being larger than the inside dimensions of the first fuel inlet
24
. A second fuel inlet
26
having inside dimensions larger than those of the first fuel inlet
24
and a second fuel outlet
27
having inside dimensions smaller than those of the first fuel outlet
25
are formed in the second plate
23
. The valve main body
19
is provided with: 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: an aluminum casing
50
housing the valve assembly
20
inside a second recess
50
b;
a cylindrical sleeve
30
housed in surface contact with the second plate
23
of the valve assembly
20
; a piston
33
slidably inserted inside the sleeve
30
forming a fuel pressurization chamber
32
in cooperation with the sleeve
30
; and a first spring
36
disposed between a recessed bottom surface
34
of the piston
33
and a holder
35
, the spring
36
applying force to the piston
33
in a direction which expands the volume of the fuel pressurization chamber
32
.
The high-pressure fuel supply body
21
also includes: a housing
37
fitted over the sleeve
30
; a ring-shaped securing member
38
securing the valve assembly
20
, the sleeve
30
, and the housing
37
inside the second recess
50
b
of the casing
50
by fitting over the housing
37
and engaging the second recess
50
b
of the casing
50
by means of a male thread portion formed on an outer circumferential surface of the securing member
38
; a stainless-steel bellows
40
disposed between the housing
37
and a receiving portion
39
secured to a tip portion of the piston
33
; a second spring
41
compressed and disposed around the outside of the bellows
40
between the housing
37
and a holder
42
; and a bracket
43
disposed to surround the second spring
41
, the bracket
43
being secured to the casing
50
by a bolt (not shown).
The high-pressure fuel supply body
21
also includes: a tappet
44
slidably disposed in a slide bore
43
a
in an end portion of the bracket
43
; a pin
45
rotatably suspended in the tappet
44
; a bush
46
rotatably disposed on the pin
45
; and a cam roller
47
rotatably disposed on the bush
46
, the cam roller
47
contacting a cam (not shown) secured to a cam shaft (not shown), following the shape thereof, and reciprocating the piston
33
.
The high-pressure regulator
10
is disposed inside a third recess
50
c
in the casing
50
. The high-pressure regulator
10
includes: a valve
80
reciprocating axially; a holder
81
disposed opposite the valve
80
; an adjusting screw
82
for determining the axial position of the holder
81
, a tip of the screw contacting the holder
81
; a spring
83
compressed and disposed between the valve
80
and the holder
81
; a pipe
84
surrounding the holder
81
and a portion of the valve
80
; a stainless-steel valve seat
85
formed with a passage
86
in which the valve
80
reciprocates; and a plate
87
forming a volume chamber
88
for damping the valve
80
, the plate
87
being joined to the valve seat
85
by welding. Moreover, the valve seat
85
is secured inside the third recess
50
c
at the entrance to the third recess
50
c
by means of the pipe
84
, and a securing thread
89
is engaged at a central portion by the adjusting screw
82
which moves inwards and outwards axially.
In a high-pressure fuel supply assembly
100
having the above construction, the piston
33
is reciprocated by the rotation of the cam secured to the cam shaft of an engine (not shown) by means of the cam roller
47
, the bush
46
, the pin
45
, and the tappet
44
.
When the piston
33
is descending (during the fuel intake stroke), the volume of the inside of the fuel pressurization chamber
32
increases and the pressure inside the fuel pressurization chamber
32
decreases, and when the pressure inside the fuel pressurization chamber
32
becomes lower than the pressure in the first fuel inlet
24
, the intake-side tongue
28
of the valve main body
19
bends towards the second fuel inlet
26
, allowing fuel in the low-pressure fuel supply passage
1
to flow through the first fuel inlet
24
into the fuel pressurization chamber
32
.
When the piston
33
is ascending (during the fuel discharge stroke), the pressure inside the fuel pressurization chamber
32
increases, and when the pressure inside the fuel pressurization chamber
32
becomes greater than the pressure in the first fuel outlet
25
, the discharge-side tongue
29
of the valve main body
19
bends towards the first fuel outlet
25
, allowing fuel in the fuel pressurization chamber
32
to flow through the first fuel outlet
25
and the fuel discharge passage
7
into the high-pressure damper
8
, where fuel pressure surges are absorbed. High-pressure fuel is then supplied to the check valve
13
and the delivery pipes
15
, and thereafter supplied to the fuel injection valves
16
, which inject fuel into each of the cylinders
Nishitani Shoichiro
Onishi Yoshihiko
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tyler Cheryl J.
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