Note: Descriptions are shown in the official language in which they were submitted.
DISCHARGE VALVE FOR A FUEL TANK
Backqround of the Invention
Field of the Invention
This invention relates to a discharge valve for the fuel
tank of a vehicle with at least two inlet ports.
A number of motor vehicles, such as utility vehicles and
agricultural tractors in particular, require relatively large
fuel tanks that have relatively large length and width
dimensions with respect to their height dimension, in order to
comply with space requirements and to provide large ground
clearance for the vehicle. If such elongated fuel tanks are
filled only partially, the fuel in the tank will collect on
the lower side of the tank if the vehicle is inclined, which
can occur during hill climbing or operation in furrows. If
the suction port, from which the fuel pump draws the fuel,
lies in this lowered side of the tank, then there is no
problem. If, however, the suction port lies in another
region, it can find itself above the surface of the fuel when
the vehicle is inclined, although the tank still may contain a
large amount of fuel.
In order to utilize the entire volume of the tank during
operation on an incline without ingesting any air, it is
advantageous to locate fuel suction ports at various places
along the bottom of the tank. Extraction of the fuel could
then be performed only on the condition that fuel pumps are
connected to each of the suction ports, since the electrically
driven pumps are lubricated by the fuel pumped and cannot be
allowed to run dry.
Accordingly, it is appropriate to utilize a discharge
valve which is inserted between the fuel tank suction ports
and the fuel pump which blocks the connection between the
suction port that is drawing in air and the fuel pump.
US Patent No. 2,332,007 discloses a known discharge valve
for an aircraft fuel tank. This discharge valve permits
suction of the fuel from the lower of two suction ports. The
discharge valve contains two inlet ports connected to the
suction ports and a central outlet port connected to a fuel
pump. The valve body contains two ball-shaped valve
components that move against and close associated valve seats
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under the influence of gravity. The two valve components are
spaced by a rod in order to avoid closing both suction
channels simultaneously. This valve, intended for aircraft
applications is a relatively costly configuration.
Accordingly, it would be desirable to provide a discharge
valve of the type described above suitable for motor vehicles
that provides a simple, cost effective assembly.
Summary of the Invention
An object of the present invention is to provide a fuel
tank discharge valve of the type described above which is
- simple and cost effective and suitable for motor vehicles.
This and other objects are achieved by the fuel tank
discharge valve of the present invention which has a generally
cylindrical housing having a pair of inlets at opposite ends
thereof for connecting to fuel tank discharge ports, and a
central outlet for connecting to a fuel pump inlet. A cage is
movable in the housing and carries at opposite ends seals
which can close the inlet ports. The cage includes abutments
connected by struks between which a ball can roll freely upon
the inner surface of the housing. A ball is movable to move
the cage. The struts are guided between a pair of rails that
project inwardly and extend axially in the upper part of the
housing. These parts are dimensioned so that one of the inlet
ports is always connected to the outlet port so that fuel can
be pumped from the fuel tank at all times. If the horizontal
orientation of the vehicle and therewith the fuel tank and the
discharge valve is changed, the ball will roll to the lowest
point, impinge against one of the abutments and move the cage
and one the seals into sealing engagement with one of the
inlets. The discharge valve prevents air from being ingested
into the fuel system in hill climbing and operation on terrain
that is not horizontal.
Guide sections at each end of the cage are axially
slidably supported in bores in the ends of the valve housing.
Grooves extend axially in the outer surface of the guide
sections, which permit fuel to flow from one of the inlet
ports to the outlet port when the inlet port is open.
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The closing action of the ball can be aided with a
pressure assist according to further embodiments of the
invention. In one such embodiment, a pilot valve is movable
by the cage and controls communication of fluid pressure to
one end or the other of the cage to assist in the closing of
the appropriate inlet. The fluid pressure is provided by a
part of the fuel flow branched off from that transported by
the fuel pump.
~n a further embodiment of the invention the cage and
ball are received in separate housing which is connected to
the valve housing by a hollow neck. A lever is pivoted in the
neck and has one end rigidly connected to the cage and another
end engaging the valve body or to a pilot valve movable in the
valve housing. Depending upon the length of the lever, the
closing force provided by the ball and cage is amplified.
Brief Description of the Drawings
Fig. 1 is a longitudinal sectional view of a fuel tank
discharge valve according to the present invention;
Fig. 2 is a cross sectional view along lines 2-2 of Fig.
1.
Fig. 3 is a longitudinal sectional view of a fuel tank
discharge valve according to a second embodiment of the
present invention;
Figs. 4, 5 and 6 are longitudinal sectional views of a
third embodiment of the invention including closing pressure
amplification shown in various positions;
Figure 7 is a cross sectional view along the line 7-7 in
figure 6.
Figures 8 and 9 are longitudinal sectional views of a
forth embodiment of the invention showing the discharge valve
in two valve positions.
Figure 10 is a cross sectional view along the line 10-10
in figure 6.
Detailed Description
The discharge valve according to Figs. 1 and 2 consists
of a generally cylindrical valve housing 10 with an inlet port
12 and a hose connection 14 at each end. In the central
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region of the valve housing 10 an upward directed outlet port
16 branches off with a further hose connection 18, which is
connected to a fuel pump 17. The discharge valve is
preferably installed at the level o~ the bottom o~ the fuel
tank.
Each of the inlet ports 12 is connected by lines with a
suction port in the bottom region of a vehicle fuel tank 19.
One of the suction ports may be located in the forward region
of the tank, in the direction of travel, the other suction
port may be located in the rear region of the ~ank. When the
tank is only partly ~illed and the tractor is climbing up a
hill, only the rear suction port may be covered with fuel, and
when the tractor is descending a hill, only the forward
suction port may be covered with fuel. As long as the
discharge valve cnnnects the fuel pump at all times with the
suction port that is covered with fuel, an adequate fuel
supply is assured at low tank fill levels even in steep hill
climbs and descents. The suction ports are preferably cross
connected to the inlet ports 12 of the discharge valve. For
example, the forward inlet port is connected to the rearward
suction port, and the rearward inlet port is connected to the
forward suction port. By this means the inlet port connected
to the more elevated suction port is always blocked, and hence
the discharge valve prevents air from being drawn through the
suction port by the fuel pump and reaching the fuel supply
system when climbing a hill or operating on inclined terrain.
In the valve housing 10 a valve body or cage 20 is
arranged so as to slide freely in the axial direction. The
cage 20 has two abutments 22 that are connected to each other
by two struts 24. Each abutment 22 carries an outwardly
extending guide section 26 which is slidably received in a
reducer diameter cylindrical section 28 of the valve housing
10. The cage 20, with its two connecting struts 24 is guided
and retained between two axial rails 38 which project inward
in the valve housing 10. The rails 38 form bearing surfaces
which slidably engage the struts 24. The rails 38 prevent
~ ~ 1 4 ~ ~ ~
rotation of the cage 20 and thereby assure that the struts 24
always remain in the upper region of the valve housing.
Seals 30 of a rubber-like material are attached at the
end faces of the guide sections 26. The seals 30 are
sealingly engageable with opposed sealing surfaces or valve
seats 32 that are located at the inner ends of the inlet ports
12. If the cage 20 is moved axially within the housing 10 to
its end position, then the seal 30 is forced against the
corresponding valve seat 32 and the associated inlet port 12
is closed. An appropriate sealing material includes metallic
surfaces, plastic or rubber, where rubber or rubber-like seals
are preferred. The sealing surface may be configured as a
plane, ball-shaped, conical or self-centering. In each case
the sealing surface may be applied to the valve body or in the
area of the inlet port, while the seal material is attached to
the mating part in each case.
The guide sections 26 are provided on their circumference
with axial ribs 34 which support them within the cylindrical
sections 28 in the valve housing 10. The ribs 34 are
separated bv axial recesses that are used as connecting
channels. When one of the valve seats is opened, fuel flows
from the inlet port 12 through the axial recesses to the
outlet port 16. The ribs 34 assure a low sliding friction of
the cage 20 in the valve housing 10.
The cage 20 can be moved in axial direction by the
kinetic energy of a ball 36. The ball 36 is received in the
valve housing 10 between the abutments 22 of the cage 20. In
the present embodiment the space between the abutments 22 is
approximately twice as large as the diameter of the ball 36 so
that it can roll freely between the abutments 22 along the
inner wall of the valve housing 10. If the vehicle or the
fuel tank is oriented horizontally, the ball 36 takes on a
central position in the valve housing. If, however, the
vehicle with the tank and the discharge valve is inclined, the
ball 36 will roll to the lower position due to the inertia
forces and apply an impulse to the cage 20, under the force of
2~.7~
which it moves toward and closes the lower inlet port with its
seals.
Both the fuel in the fuel tank and the ball 36 are
exposed to inertia forces such as those caused by braking or
cornering of the vehicle. The ball is able to move within the
valve housing 10 to close the appropriate one of the valve
seats in response to inertia forces as well as gravity.
Because the ball 36 is able to roll free between the abutments
22, the ball 36 builds up kinetic energy before it impinges
upon the abutment 22 of the cage 20 and transmits its kinetic
energy to the latter with a corresponding impulse. The ball
rolls with little friction so that in practice it avoids an
indeterminate position and always has a tendency to make
contact with one abutment and to close the corresponding inlet
port.
The valve housing 10 is preferably rigidly connected to
the vehicle structure (not shown) and is oriented horizontally
with respect to the vehicle (not shown). The longitudinal
axis of the valve housing 10 is preferably oriented parallel
to a imaginary line connecting the two suction ports in the
bottom region of the fuel tank 19. If the vehicle (not shown)
is inclined, for example, in operating downhill, then the
valve housing 10 inclines in the same direction. Under the
force of gravity the ball 36 rolls freely toward one end of
the valve housing and thereby moves the cage 20 to close one
of the valve seats 32 while the other valve seat 32 remains
open. The port of the discharge valve that is now lying higher
and remains open is connected to the lower fuel tank suction
port which is submerged in fuel, so that only fuel will flow
to the outlet port 16. Since the other inlet port is closed,
no fuel or air will flow through it and no air will be
ingested by the fuel pump 17.
In vehicles that are frequently operated at an
inclination perpendicular to the direction of travel, which
may be the case, for example, with agricultural tractors
operating in a furrow, the suction ports and therewith the
discharge valve may be arranged in the direction perpendicular
to the direction of travel. A diagonal arrangement could also
be considered in order to optimize fuel discharge in both
longitudinal and crosswise inclination of the vehicle.
The valve housing 10 and the valve body may be
manufactured from a plastic that provides a good match in
sliding characteristics, while the ball 36 preferably consists
of a material with high density, for example steel or brass,
in order to apply the necessary impulse.
Figure 3 shows a further embodiment of the inventiQn.
The discharge valve 11 of Fig. 3 includes pressure assisted
closing. The valve 11 has a cylindrical valve housing 40 with
an inlet port 42 at each end and an upward opening central
outlet port 44 connected to a fuel pump 46. The fuel pump 46
pumps the fuel through the line 48 to the fuel injection pump
(not shown) of the vehicle engine (not shown). Two lines 50
branch off from line 48 and are connected to upward directed
inlet channels 52, 54 in the valve housing 40 which conduct
pressurized fuel into the interior of the valve housing 40.
The fittings for the inlet ports 42, the outlet port 44 and
the inlet channels 52, 54 may be configured as hose
connections.
A valve body 55 is free to slide axially within the valve
housing 40. The central region of the valve body 55 forms as
a cage 56 which is movable between two separating walls 58
which are connected to the valve housing 40. The cage 56 has
two abutments 60 connected to each other by connecting struts
62. Hollow, generally cylindrical projections 64 extend
axially outward from the abutments 60. Each projection 64
extends through one of the separating walls 58, and each is
connected to a piston 66, which is slidably supported in the
valve housing 40. A pair of piston chambers 67 are enclosed
between pistons 66 and the separating walls 58. The outer
periphery of each piston 66 forms a cylindrical valve surface
68 which is able to close off the corresponding one of the
inlet channel 52, 54. A seal 70 of rubber-like material is
mounted on an axial outer end face of each piston 66. Each
seal 70 is positioned opposite to and is engageable with a
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sealing surface or va]ve seat 72 in the valve housing 40 for
closing one of the inlet ports 42.
A channel 74 extends through the piston end face and the
hollow cylindrical projection 64 forms a channels 76. When
one of the seals 70 is not in contact with the corresponding
sealing surface 72 and the corresponding inlet 42 is open,
fuel can flow through that inlet port 42, through the channels
74, 76, past the separating wall 58, around the abutment 60
and through the outlet port 44 to the fuel pump 46. This flow
is indicated by arrows on the right side of the Fig. 3. When
the seal 70 is in contact with the sealing surface 72 the flow
of fuel as well as the ingestion of air is stopped.
A ball 78 is free to roll upon the inner wall of the
valve housing between the abutments 60 of the cage 56 and is
provided with a space for motion between the abutments 60.
Further details of the discharge valve shown in Fig. 3 and its
connections to the fuel tank suction ports ar similar what is
shown in Figs. 1 and 2, and are not again described here, in
order to avoid repetition.
The operation of the discharge valve shown in Fig. 3 is
as follows:
If the vehicle accelerates or decelerates, or if the
vehicle, and therewith the fuel tank and the discharge valve
11, is inclined, then the ball 78 moves the cage 56 due to
gravitational or inertia forces, for example, to the left
viewing Fig. 3. Accordingly, the left piston 66 moves to the
left and opens the inlet channel 52 so that pressurized fuel
from the fuel pump 46 can enter a left piston chamber 67
between the separating wall 58 and piston 66. The pressure in
chamber 67 moves the piston 66 further to the left and forces
seal 70 against the sealing surface 72 and closes the left
inlet port 42. Simultaneously, the right piston 66 moves
leftward into the interior of the valve housing 40 and its
sealing surface 68 closes the inlet channel 54 so that no
pressurized fuel can enter the right piston chamber 69 of the
valve housing and thus load the right piston. In this
position the right inlet port 42 is open and fuel can flow
A S'i ~, ;3
through the connecting channels 74, 76 to the outlet port 44.
A aimilar operation occurs if the ball 78 rolls to the right.
Thus, the movement of the cage 56 body is enhanced by the fuel
pressure.
Figs. 4, 5, 6, 7 and lo illustrate a further embodiment
of the invention which is a dischar~e valve 101 with closing
pressure amplification. This valve 101 has a cylindrical
valve housing 80 with an inlet port 82 at each end for
connection to the suction ports in the fuel tank. An outlet
port 84 branches off from each end of a central portion of the
valve housing 80 for connection to the suction side (P0) of
the fuel pump 85. A pair of inlets 86 are formed in the
central portion of the valve housing 80 between the outlets
84. The inlets 86 are connected with the pressure side (P1)
of the fuel pump 85.
A valve body 88 moves axially freely within the valve
housing 80 and has seals 90 at each end thereof, in order to
close the inlet ports 82. Both end regions of the valve body
88 are slidably received in hollow cylindrical sections 92 of
the valve housing 80. Each end region has axially extending
slots 94 which permit fuel to flow from the inlet ports 82 to
the outlet ports 84. Two spaced apart pistons 96 are fixed to
and carried with the central portion of the valve body 88.
A slide 98 is axially moveable within the valve housing
80 and includes two cylindrical segments 98a and 98b, best
seen in Fig. 7, and two annular rings 100 connected to the end
faces the two segments 98a, 98b. The outer surface of the
slide 98 slidably engages the inner surface of the valve
housing 80. The two pistons 96 mounted on the valve body 88
slidably and sealingly engage the inner walls of the slide 98
and thus, close off a central region of the slide 98 in the
axial direction, as best seen in Fig. 10.
A portion of the valve housing 80 forms a separating wall
102 which lies between the two pistons 96 and which defines
two piston chambers 104 within the slide 98. The valve body
88 slides through a central opening in the wall 102. A pair
of radial bores 106 extend through the segment 98b of the
.
slide 98, each communicating with one of the piston chambers
104. The slide 98 is axially moveable to open communication
between one of the piston chambers 104 and one of the two
inlet channels 86.
A further housing 110 is connected to the valve housing
80 by a neck 112. The housing 110 r~ceives a cage 114 with
two arms 116 which extend away from each other and from an end
of a lever 120 which is pivotally supported in the housing 110
on a pivot 124 mounted in the neck 112. A ball 118 is
retained in the housing 110 between the arms 116 so that the
ball 118 is free to roll back and forth, parallel to the axis
of the valve housing 80. The arms form a surface 115 on which
the ball 118 rolls and which is bowed upward slightly, so that
the ball will be in a stable position when it engages one or
the other of the arms 116 and so that it will be at the right
or the left side of the cage 114. An inclination of
approximately 5 degrees from the horizontal is required before
the ball 118 will roll from one position to the other.
An inner end 122 of the lever 120 engages a recess in the
slide 98. Thus, a swinging of the cage 114 to the right
produces an axial motion of the slide 98 to the left (or the
inverse). By the design of the proportions of the lever to
each side of the pivot bearing 124 a path relationship and
force transmission can be established to conform to the
requirements of the particular application. In the
illustrated embodiment the segment of the lever 120 that
extends into the valve housing 80 is shorter than the distance
from the pivot bearing 124 to the center of the ball 118. As
a result a certain motion of the cage 114 produces a smaller
motion of the slide 98, ~ut the force applied by the ball 118
to the cage 114 is, amplified by the lever ratio as it is
transmitted to the slide 98.
The discharge valve 101 of Figs. 4-7 may be oriented in
the vehicle in any desired direction. It is necessary only to
insure that the surface on which the ball rolls is
approximately horizontal when the fuel tank is oriented
horizontally. Unlike the discharge valve of Figs.
2 13 ~
1-3, the inlet ports 82 do not have to be cross connected to
the suction ports in the bottom of the fuel tank, but are
connected directly, that is, the forward inlet port 82 is
connected to the forward suction port and the rear inlet port
82 is connected to the rear suction port.
The operation of the discharge valYe according to Figs.
4-7, and 10 is as follows:
If the discharge valve 101 is inclined from its
horizontal position, so that one inlet port 82 is higher than
the other, then the ball 118 will roll in the housing 110 to
the lower lying side, engage the corresponding arm 116 and
rotate the cage 114 and lever 120 about the pivot bearing 124.
The free end of the lever 122 moves the slide 98 out of its
central position, as illustrated in Fig. 6, to one of the side
positions as shown in Fig. 4 or 5. As the slide 98 moves one
of the radial bores 106 will be brought at least partially
into alignment with one of the inlet channels 86, so that the
corresponding chamber 104 is connected to the fuel pump 85 and
is subjected to the its pressure Pl. Under the force of this
pressure Pl the valve body 88 is moved to its end position
whereby one of the seals 90 closes the corresponding inlet
port 82.
The other piston chamber 104 is not subjected to the full
pressure Pl of the fuel pump, sinc~ the corresponding radial
bore 106 is not in alignment with the corresponding inlet
channel 86 and the pressure in this other piston chamber 104
is dissipated by leakage past piston 96 to the outlet port 84.
If the ball 118 rolls to the other side, then the slide 98 is
moved to the other side by the cage 114, so that the other
piston chamber is put under pressure and the valve body 88
closes the other inlet port 82.
The Figs. 8 and 9 show two positions of another
embodiment of a discharge valve 121. The valve 121 has a
cylindrical valve housing 130 with inlet ports 132 at opposite
ends thereof, each for connecting to a suction port in the
fuel tank. An outlet port 134 for connecting to a fuel pump
opens into the central portion of the valve housing 130. A
2 ~ 8
valve body 136 is axially moveable in the valve housing 130
and has slots 139 which extend axially along its outer
surface. A seal 138 i6 attached to each end of the valve
body 136 for closing a corresponding one of the inlet ports
132. Fuel can be drawn by the fuel pump through the open
inlet port 132, through the slots 139 and to the outlet port
134.
The valve body 134 can be moved axially by the same ball,
cage and lever mechanism as already described in connection
with Figs. 4 through ~. The discharge valve 121 of Figs. 8
and 9 does not have a pressure assisted closing operation.
While the invention has been described in conjunction
with a specific embodiment, it is to be understood that many
alternatives, modifications and variations will be apparent to
those skilled in the art in light of the foregoing
description. Accordingly, this invention is intended to
embrace all such alternatives, modifications and variations
which fall within the spirit and scope of the appended
claims.
