FIELD OF INVENTION
This invention relates to expansion hose for reduction in the pump/ rail
pressure and volume fluctuation.
PRIOR ART
Some currently available vehicles face low NVH performance, wherein noise is
very much predominant in diesel vehicles as compared to gasoline vehicles.
Noise caused may be due to fuel pressure pulsations. Also, it may be due to
injector pulses/LP or HP pump pulses/sudden cross section change etc.
The fuel from High pressure pump suddenly enters a small cross section (pipe,
then rail). As a result of sudden pressure drop/rise, the fuel gets pulsed, which
creates bubbles, that get exploded inside the common rail/fuel rail. The sound
generated at the source travels as longitudinal waves through the liquid or
through the walls causing noise.
Also during injection, the fuel enters the injector from rail.However, after
injection the injector closes suddenly, which creates a backpressure/pulsation
in fuel air generating noise. •
Hence, there is a need for low pressure drop to avoid cavitations/bubbles
which generates noise.
In order to address the aforesaid problem, pulsation dampener is known to
have been provided for reducing the pressure of the fuel system for both FE
improvement and noise reduction. However, noise is still generated in small
cars with use of flow rate pumps. Said dampener having cross section of an
accumulator type/spring loaded diaphragm.
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The dampers are shown in fig. 1 are considered according to their spring I
stiffness. However, the disadvantage is that it is expensive.
Now, reference may be made to the following prior arts:-
US 4611633:- An expansion hose having a central internal throttle element
dividing the interior of the hose into two chambers, and an internal hose
extending from the expansion hose inlet through one of the chambers and the
throttle element into the second chamber. The portion of the inner hose within
the first chamber has radial throttle passages, and the portion within the
second chamber is imperforate.
JP2002081800A;- A variable throttle valve is disposed at an upstream side of
a refrigerant flow, and a fixed throttle valve is disposed at a downstream side of
the valve. An intermediate space is provided between the valve and the valve,
and the cross-sectional area of the flow path of the space is set larger than
that of the valve. The path length L of the intermediate space is set a length not
smaller than a specified length required for allowing the refrigerant flow jetted
from the valve to be expanded wider than the path cross-sectional area of the
j valve.
US 4611633;- It makes use of perforations as passages for expansion without
any slot passages (which reduces bubble formation), throttle plate, spring
elements (not of dynamic control).
J P 2002081800;- It uses filter mesh for filtration with fixed throttle as the exit
passage by providing small exit opening. Again, only one length of control is
provided after dampening in downstream.
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OBJECTS OF THE INVENTION
The primary object of the present invention is to provide expansion hose for
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reduction in the Pump/ Rail pressure and volume fluctuation which overcomes
disadvantages associated with the prior art.
Another object of the present invention is to provide expansion hose for
j reduction in the pump pressure and volume fluctuation which improves the
NVH performance of automobile.
Yet another object of the present invention is to provide expansion hose for
reduction in the pump pressure and volume fluctuation which is reliable 85
efficient.
STATEMENT OF INVENTION
According to this invention there is provided expansion hose for reduction in
the pump pressure and volume fluctuation comprising of outer hose
accommodating inner hose provided with an expansion slot at one end and a
throttle at other end with a helical spring.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings and wherein:
Figure 1 shows: conventional dampers.
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Figure lA shows: diesel fuel system.
Figure IB shows: gasoline fuel system.
Figure 2 shows: expansion hose for reduction in the pulsation pressure and f
volume fluctuation according to the present invention.
Figure 3 shows: pressure pulsation comparison for expansion hose with
dynamic throttle according to the present invention.
Figure 4 shows: pressure pulsation comparison for expansion hose with static
throttle according to the prior art.
Figure 5 shows: pressure pulsation comparison for expansion hose with two
slots and without throttle according to the prior art.
Figure 6 shows: pressure pulsation comparison for expansion hose with four
slots and without throttle according to the prior art.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
As already discussed, the conventional dampers are expensive.
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Now, reference may be made to fig. lA indicating diesel fuel system showing
the following:-
1. Injector (1)
2. HP Pump (2)
3. Common Rail (3).
4. Fuel Filter (4)
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5. Fuel Pipe (5)
6. Pump (6)
7. Pressure Relief Valve (7)
8. Passage of fuel from HP pump through hose/conduit to the rail.
However, as a result of sudden cross section change/pressure drop (from HP
Pump to conduit) rotation of LP Pump, Injector Pulse, Cavitations occurs and
due to bubble implosions noise occurs.
Again, reference may be made to fig. IB indicating Gasoline fuel system
showing the folio wing:-
1. Delivery pip (1)
2. Hose connecting Fuel Pipe Ss Delivery Pipe (2)
3. Fuel Pipe (3)
4. Pump (4)
However, as a result of sudden cross section change/pump rotation, Injector
pulse, cavitations generated 85 further due to bubble implosions noise occurs.
The present invention discloses expansion hose for reduction in the pump
pressure and volume fluctuation. Now, reference may be made to fig. 1,
wherein said expansion hose comprising of outer hose accommodating inner
hose provided with an expansion slot at one end and a throttle at other end
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with a helical spring. Further, a spacer is provided between outer and inner I
hose.
The inner hose carries pulsating fluid and the outer hose acts as an expansion
chamber, wherein both the hoses are concentric.
Said expansion slot expands the fluid to the expansion chamber.The slot
provided on the periphery of inner hose connects the pulsating fluid at inner
hose to expansion chamber of the outer hose.
The spacer acts as bubble cutter, which also maintains the concentricity
between the two hoses.
The throttle plate dampens the fluid with high pressure pulsations. It is
positioned on stopper. Said conical helical compression spring supports the
throttle plate against the fluid flow and dampens the pulsating fluid flow,
wherein a valve seat is provided to position the spring. The compression spring
with throttle plate on stopper and valve seat are accommodated in the inner
hose. The throttle may be convergent type, plate type or a diaphragm without
restricting scope of the invention to the same. Any other type readily apparent
to a person skilled in the art is understood to be within the scope of the
invention.
In the present invention, the hose is optimized by means of slot passages,
bubble cutter/ spacer, expansion chamber volume together with 3 key length of
control for pulsation control (viz.. Length between entry of fuel into expansion
hose till the slots. Length between entry of fuel into expansion hose till throttle
plate determines the expansion (upstream side). Length after dampening
(downstream side)).
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The Pulsating fuel from High / Low pressure pump entering the expansion
hose is subjected to gradual or smooth expansion (PI, VI to P2,V2) even if it
expands suddenly 85 creates a bubble, the bubble cutter / thin plate with multi
slot cuts the bubble, which gets exploded in the hose (P2,V2 to P3,V3) itself.
The high pressure center fuel particles {P1,V1) passing via the throttle d& with
less pressure drop , gain little kinetic energy (P4, V4) to mix with the
expanded fluid (P3,V3)
As a result of the center fluid (High kinetic energy fuel) with an envelope of low
kinetic energy fuel, the noise of the system reduces (from higher decibel level to
lower).
In general
P1>P4>P2>P3
V4>V1>V3>V2
The present invention provides a chamber of sufficient volume to allow an
extension of time in which a given flow may be accelerated or decelerated
without sudden large change in pressure, which expands the high pressure
pulsating fuel in an expansion chamber.
Rest of the fuel flowing inside the inner hose / tube /pipe having outside fuel
particles with high pulsation tendency is dampened by dynamic throttle /
dampener on the fluid path
The center fluid particles having higher velocity 85 pressure flows through the
Dynamic Throttle (which may be convergent type / plate type)which results in
Subsonic or non-choked flow
The expanded fuel may have bubbles which can be exploded at the expansion
/outer hose itself using a bubble cutter /thin plate
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As a result of the center fluid (High kinetic energy fuel) with an envelope of low
kinetic energy fuel, the noise of the system reduces (from higher decibel level to
lower).Existing hose / conduit can be modified to obtain the present invention.
Finally, reference may be made to fig. 3-6 indicating comparison of pressure
pulsation of present invention and conventional expansion hoses, observations I
in respect of which is as follows:-
S. No. Concepts Details Pressure Pulsation Remarks
Reduction (bar)
1 Concept A Expansion Hose with 2
slots, Diaphragm with 4+/-0.75 to 4 +/- OK
Spring (Dynamic Throttle) 0.25
2 Concepts Expansion Hose with 2 4+/0.75 to 4
slots. Diaphragm W/O +/0.50 Pulsation
spring (Static Throttle) reduced little
3 Concept C Expansion Hose with 2 4+/0.75 to In 1 cycle ->
Slots, W/o Diaphragm, 4+/0.75 (cycle 1,3 Pulsation
W/o spring ) remains same,
4 +/0.75 to 4 Flow is affected
+/0.25 (cycle 2, 4)
4 Concept Expansion Hose with 4 4+/0.75 to In 1 cycle ->
D Slots, W/o Diaphragm, 4+/0.75 (cycle 1,3 Pulsation
W/o spring ) remains same,
4 +/0.75 to 4 Flow is affected
\ \ I +/0.25 (cycle 2, 4) | |
From the above, it can be concluded that, reduction in pressure pulsation can
be achieved by the present invention (concept A) effectively than the known art
(concept B, C and D).
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Advantageous Features
Reduction in travel of compression wave (As a result of high pressure pump)
Expansion of the fluid with low pressure drop
Reduction in Hydraulic Pressure Pulsations
Reduction of bubbles / Cavitations
Increase in the life of components (Injector, Del Pipe, HP Pump)
Elimination of pulsation dampener
Reduction in the Noise (fluid borne 85 structure borne) ^
Acts as flexible element (can be used for any applications depending on the
need to reduce the pressure pulsation /Noise)
Can be used for high performance applications (with no need for reducing
pressure to reduce the noise).
Applications
a. Placed closely before a valve that is closed quickly. Stops water hammering.
b. Placed adjacent to the discharge of a pump that is started fast in to a pipe
full of a long column of liquid. Reduces start up surge pressure.
c. Placed adjacent to a pump, which when caused to stop suddenly, enables a
vacuum to form, which pulls the flow back towards the pump. Prevents an
implosion bang.
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It is to be noted that the present invention is susceptible to modifications,
adaptations and changes by those skilled in the art. Such variant embodiments
employing the concepts and features of this invention are intended to be within l
the scope of the present invention, which is further set forth under the
following claims:

WE CLAIM;
1. Expansion hose for reduction in the pump / rail pressure and volume
fluctuations comprising of outer hose accommodating inner hose
provided with an expansion slot at one end and a throttle at other end
with a spring.
2. Expansion hose as claimed in claim 1, wherein a spacer is provided
between the outer and inner hose, which acts as bubble cutter.
3. Expansion hose as claimed in claim 1 or 2, wherein the inner hose
carries pulsating fluid and the outer hose acts as an expansion chamber,
wherein both the hoses are concentric.
4. Expansion hose as claimed in any of the preceding claims, wherein said
expansion slot on the periphery of inner hose expands the fluid to the
expansion chamber, which connects the pulsating fluid at inner hose to
expansion chamber of the outer hose.
5. Expansion hose as claimed in any of the preceding claims, wherein said
conical helical compression spring supports the throttle plate against the
fluid flow and dampens the pulsating fluid flow.
6. Expansion hose as claimed in claim 5, wherein a valve seat is provided to
position the spring and said throttle plate is positioned on stopper.
7. Expansion hose as claimed in any of the preceding claims, is associated
with the advantageous features such as herein described.
8. Expansion hose for reduction in the pump pressure and volume
fluctuation substantially as herein described with reference to the
accompanying drawings.