Field of the Invention
[0001] The present invention relates to a valve arrangement. In particular, the present
invention relates to a valve arrangement for a fuel injector.
Background to the Invention
[0002] The present invention relates to a valve arrangement used in the delivery of fuel
to a cylinder of a diesel internal combustion engine of the type in which fuel is
supplied to a high pressure accumulator (the "common rail") by a suitable pump and
is delivered from the accumulator to the fuel injectors of the engine, the nozzles
of which are arranged to actuate in turn to deliver fuel to the respective cylinders
of the engine.
[0003] Such fuel injectors generally comprise a needle which is slidable within a body and
engageable with a valve seat to control the flow of fuel from a high pressure fuel
supply line through the body.
[0004] The maximum injection pressures within a fuel injector may be of the order of 1800
bar or higher and as a consequence the forces to be overcome in order to lift the
needle of the injector are large. It is not therefore possible to directly control
the injector using an electromagnetic actuator unless very high currents are used.
The injector is therefore indirectly controlled by means of a valve arrangement which
controls the pressurising or discharging of a control chamber located above the valve
needle.
[0005] An example of such an injector is disclosed in
EP0647780 in which the end of the needle remote from the valve seat extends within a chamber,
the chamber being arranged to receive fuel from the supply line through a restrictor.
In use, injection is controlled by varying the pressure within the control chamber.
A solenoid actuator acts upon a valve arrangement to cause a flow path between the
control chamber and a low pressure drain to open. As the pressure falls within the
control chamber the needle leaves the valve seat due to pressure acting against a
portion of the needle adjacent the valve seat. Within common rail injection systems
two types of valve arrangements are known, pressure-balanced valve arrangements (sometimes
referred to as equilibrium valves) and non-pressure balanced valve arrangements.
[0006] In a pressure balanced valve arrangement a valve stem located within a bore is slidable
under the action of the electromagnetic actuator to open and close a flow path between
the high pressure region of the control chamber and the low pressure region of a low
pressure drain. In the closed configuration the valve arrangement is in contact with
a valve seat and is substantially in hydraulic equilibrium, with the valve arrangement
being held in the closed position by the action of a spring on the valve arrangement.
Upon actuating the electromagnetic actuator the spring force is overcome and the valve
arrangement moves away from its seat thereby allowing fuel to move between the stem
and bore to the low pressure drain. Equilibrium based valve arrangements tend to demonstrate
a degree of static leakage. In other words, even in the closed position high pressure
fuel will leak along the flow path defined between the bore of the valve arrangement
and the valve stem to the low pressure drain.
[0007] In a non-pressure balanced valve arrangement the valve is held in its seated and
closed position by the pressure of the high pressure fuel within the system. Such
a valve arrangement is not therefore substantially in hydraulic equilibrium in the
closed position and consequently requires a greater activation force in order to open.
However, the degree of static leakage within such a non-pressure balanced valve arrangement
is lower than in the pressure balanced valve arrangement.
In
DE102005029473 is disclosed an injector having a valve arrangement according to the preamble of
claim 1.
The two types of valve arrangement described above therefore either have a low actuation
force requirement with a relatively high degree of static leakage (pressure balanced
valve arrangement) or high actuation force requirement with a relatively low degree
of static leakage (non-pressure balanced valve arrangement).
It is an object of the present invention to provide a valve arrangement that has a
low actuation force requirement but which has improved static leakage performance.
Statements of Invention
[0008] According to a first aspect of the present invention there is provided a valve arrangement
for use in an injector, the valve arrangement arranged to be moveable between an open
configuration in which the valve arrangement provides a flow path for pressurised
fuel from a control chamber of the injector to a low pressure drain and a closed configuration
in which the valve arrangement closes the flow path, the valve arrangement comprising:
a valve guide located within the injector, the valve guide comprising at least a part
of the flow path; a valve head portion arranged to close a first end of the valve
guide when the valve arrangement is in the closed configuration; a biasing member
arranged to bias the valve arrangement towards the closed configuration wherein the
biasing member comprises an elastic member located within the valve guide and the
biasing member defines a volume within the valve guide.
[0009] The present invention provides a valve arrangement in which the valve arrangement
(/valve head portion) is biased towards a closed configuration by the action of an
elastic member that is located within a valve guide and which defines a volume within
the valve guide. The elastic member is in contrast to known arrangements which use
a spring arrangement.
[0010] The use of an elastic member allows the valve arrangement to be arranged to be substantially
in hydraulic equilibrium when in the closed configuration. The presence of a valve
head portion allows the valve guide to be closed by the head portion in the closed
configuration such that static leakage is minimised.
[0011] The valve arrangement of the present invention therefore provides a valve with a
relatively low degree of static leakage and a relatively low actuation force requirement.
[0012] It is noted that the elastic member/biasing member partitions the valve guide and
defines a volume within the valve guide (such that one part of the valve guide is
not in fluid communication with a second part of the valve guide).
[0013] Conveniently, the valve arrangement is arranged to be substantially hydraulically
balanced when in the closed configuration. Forces resulting from fuel pressure within
the valve guide on the valve head portion are arranged to be substantially equal to
forces resulting from fuel pressure within the valve guide on the biasing member,
the forces on the head portion and biasing member acting in substantially opposing
directions.
[0014] Conveniently, the valve arrangement comprises a valve stem portion arranged to be
located within the valve guide, the valve head portion being located at a first end
of the valve stem portion and the biasing member being located at a second end of
the valve stem portion.
[0015] In one variant of the present invention, the biasing member may comprise a substantially
planar elastic plate. In another variant of the present invention, the biasing member
may comprise a ridged plate. The presence of ridges in the plate may conveniently
allow the response characteristics of the biasing member to be varied.
[0016] In a further variant of the present invention the biasing member may be formed into
a substantially planar elastic portion and a stem portion, the valve head portion
being located at a first end of the stem portion and the elastic portion being located
at a second end of the stem portion. This variant has the advantage that it is lighter
than a version with a solid stem portion which may have performance benefits (e.g.
a more responsive valve arrangement). The stem portion may be substantially cylindrical
and comprise a number of grooves. The valve head portion may be mounted at one end
of the stem portion. Alternatively, the valve head may be of annular construction
and the stem portion may protrude through the valve head portion. This alternative
arrangement may result in a simpler construction process .
[0017] The valve guide may comprise a valve groove at a second end of the guide remote from
the first end, the biasing member being located within the valve groove. The valve
groove may have a greater cross sectional area than a main bore of the valve guide.
The biasing member forms a partition across the valve groove such that the valve head
portion and valve stem portion/valve bore are located on one side of the partition
and the volume is formed on the other side of the partition (the two sides of the
partition not being in fluid communication with each other). The volume may be filled
with fuel and be arranged to be in fluid communication with a fuel return back leak
circuit.
[0018] According to a second aspect of the present invention there is provided an injector
for use in the delivery of fuel to a cylinder of an internal combustion engine, the
injector comprising : a body provided with a bore; a valve needle slidable within
the bore of the nozzle body; an actuator; a fuel supply line for supplying pressurised
fuel to a control chamber; a valve arrangement according to the first aspect of the
present invention actuable by the actuator for permitting fuel to flow from the control
chamber to a low pressure drain.
[0019] Preferred features of the second aspect of the present invention may comprise preferred
features of the first aspect of the present invention.
Brief Description of the Drawings
[0020]
Figure 1 shows a known pressure balanced valve arrangement;
Figures 2a and 2b show the fuel injection process for a typical injector;
Figure 3 shows a valve arrangement (closed position) in accordance with an embodiment
of the present invention;
Figure 4 shows the valve arrangement of Figure 3 in an open position;
Figures 4 to 9 show further embodiments of the present invention.
Detailed Description
[0021] Figure 1 shows an example of a pressure balanced valve arrangement as described in
EP0740068.
[0022] The known fuel injector illustrated in Figure 1 comprises a valve body 10 including
a first region of relatively narrow diameter and a second, enlarged region. The valve
body 10 is provided with a bore 11 which extends through both the first and second
regions, the bore terminating at a position spaced from the free end of the first
region. An elongate valve needle 12 is slidable within the bore, the valve needle
12 including a tip region 14 which is arranged to engage a valve seat defined by the
inner surface of the valve body 10 adjacent the blind end of the bore. The valve body
10 is provided with one or more apertures 15 communicating with the bore, the apertures
being positioned such that engagement of the tip 14 with the valve seat prevents fluid
escaping from the valve body 10 through the apertures, and when the tip 14 is lifted
from the valve seat, fluid may be delivered through the apertures.
[0023] As shown in Figure 1, the valve needle 12 is shaped such that the region thereof
which extends within the first region of the valve body 10 is of smaller diameter
than the bore to permit fluid to flow between the valve needle 12 and the inner surface
of the valve body 10. Within the second region of the valve body 10, the valve needle
12 is of larger diameter, substantially preventing fluid flowing between the valve
needle 12 and the valve body 10.
[0024] In the second region of the valve body 10, an annular gallery 16 is provided, the
annular gallery 16 communicating with a fuel supply line 18 which is arranged to receive
high pressure fuel from an accumulator of an associated fuel delivery system. In order
to permit fuel to flow from the gallery 16 to the first region of the valve body 10,
the valve needle 12 is provided with a fluted region 20 which permits fuel to flow
from the annular gallery 16 to the first part of the valve body 10, and also acts
to restrict lateral movement of the valve needle 12 within the valve body 10 but not
restricting axial movement thereof.
[0025] A chamber 22 is provided within the second region of the valve body 10 at a position
remote from the first region thereof, the chamber 22 communicating with the high pressure
fuel line 18 through a restrictor 24. As shown in Figure 1, the chamber 22 is provided
at an end of the valve body 10, the chamber 22 being closed by a plate 26.
[0026] The end of the valve needle 12 remote from the tip 14 thereof is provided with a
reduced diameter projection 28, the projection 28 guiding a compression spring 30
which is engaged between the valve needle 12 and the plate 26 to bias the valve needle
12 to a position in which the tip 14 thereof engages the valve seat.
[0027] A body 34 engages the side of the plate 26 opposite that engaged by the valve body
10, the body 34 and plate 26 together defining a chamber 35 which communicates with
the chamber 22 through an aperture 32. The body 34 is further provided with a bore
which is spaced apart from the axis of the body 34 and within which a valve member
36 ("the valve arrangement") is slidable. The valve member 36 comprises a cylindrical
rod provided with an axially extending blind bore, the open end of the bore being
able to communicate with the chamber 35 when the valve member 36 is lifted such that
the end thereof is spaced from the plate 26, such communication being broken when
the valve member 36 engages the plate 26. A pair of radially extending passages 38
communicate with the blind bore adjacent the blind end thereof, the passages 38 communicating
with a chamber which is connected to a suitable low pressure drain.
[0028] The body 34, plate 26 and valve body 10 are mounted on a nozzle holder 42 by means
of a cap nut 40 which engages the end of the second region of the valve body 10 adjacent
its interconnection with the first region thereof. The nozzle holder 42 includes a
recess within which a solenoid actuator 44 is provided.
[0029] As illustrated in Figure 1, the solenoid actuator 44 comprises a generally cylindrical
core member 44a including an axial blind bore, windings 44b being wound upon the core
member 44a and being connected to a suitable controller, and a cylindrical yoke 44c
extending around the core member 44a and windings 44b. The faces of the core member
44a and yoke 44c facing the valve member 36 define pole faces.
[0030] The valve member 36 carries an armature 36a such that upon energization of the solenoid
actuator 44, the armature 36a and valve member 36 are lifted such that the valve member
36 disengages the plate 26. On de-energizing the solenoid actuator 44, the valve member
36 returns to its original position under the action of a spring 46 received within
the blind bore of the core member 44a.
[0031] A movement limiter 47 is also received within the blind bore of the core member 44a,
the movement limiter 47 being arranged to limit movement of the valve member 36 against
the action of the spring 46 in order to prevent the armature 36a contacting the pole
faces of the core member 44a and yoke 44c. It is noted that the spring 46 provides
a closing force for the valve and also maintains a contact pressure on the valve seat
when the valve is closed.
[0032] As shown in the drawing, the supply line 18 comprises bores provided in the nozzle
holder 42, body 34, plate 26 and valve body 10. In order to ensure that these bores
align with one another, pins 48 are provided, the pins 48 being received within suitable
recesses provided in each of the nozzle holder 42, body 34, plate 26 and valve body
10.
[0033] In use, in the position shown in Figure 1 the valve needle 12 is biased by the spring
30 such that the tip 14 thereof engages the valve seat and thus delivery of fuel from
the apertures does not occur. In this position, the pressure of fuel within the chamber
22 is high, and hence the force acting against the end of the valve needle 12 due
to the fuel pressure, and also due to the resilience of the spring 30, is sufficient
to overcome the upward force acting on the valve needle 12 due to the high pressure
fuel acting against the angled surfaces of the valve needle 12.
[0034] In order to lift the tip 14 of the valve needle 12 away from the valve seat to permit
fuel to be delivered from the apertures, the solenoid actuator 44 is energized to
lift the valve member 36 against the action of the spring 46 such that the end of
the valve member 36 is lifted away from the plate 26. Such lifting of the valve member
36 permits fuel from the chamber 35 and hence the chamber 22 to escape to drain through
the bore of the valve member 36 and passages 38. The escape of fuel from the chamber
22 reduces the pressure therein, and due to the provision of the restrictor 24, the
flow of fuel into the chamber 22 from the fuel supply line 18 is restricted. As the
pressure within the chamber 22 falls, a point will be reached at which the force applied
to the valve member 12 due to the pressure within the chamber 22 in combination with
that applied by the spring 30 is no longer sufficient to retain the tip 14 of the
valve member 12 in engagement with the valve seat, and hence a further reduction in
pressure within the chamber 22 will result in the valve needle 12 being lifted to
permit fuel to be delivered from the apertures.
[0035] If a low initial injection rate is desired, this may be achieved by arranging the
solenoid actuator 44 to lift the valve member 36 by only a small amount, thus the
flow of fuel from the chamber 22 to drain is restricted. Similarly, the aperture 32
may be of restricted diameter so as to restrict the flow of fuel from the chamber
22.
[0036] As the valve needle 12 lifts, the projection 28 approaches the aperture 32 restricting
the flow of fuel therethrough. It will be recognised that this has the effect of decelerating
the valve needle 12 towards the end of its travel.
[0037] In order to terminate delivery, the solenoid actuator 44 is de-energized and the
valve member 36 moved downwards under the action of the spring 46 until the end thereof
engages the plate 26. Such movement of the valve member 36 breaks the communication
of the chamber 35 with the drain, and hence the pressure within the chamber 35 and
chamber 22 will increase, a point being reached at which the force applied to the
valve needle 12 due to the pressure within the chamber 22 and due to the spring 30
exceeds that tending to open the valve, and hence the valve needle 12 will move to
a position in which the tip 14 thereof engages the valve seat to prevent further delivery
of fuel.
[0038] It will be recognised from the above description and from Figure 1 that since the
valve member 36 and solenoid actuator 44 are not coaxial with the valve needle 12,
the nozzle holder 42 and body 34 each include a region of relatively large wall thickness
compared to the conventional arrangement and by arranging for the supply line 18 to
extend within the relatively thick part of the wall, the risk of rupture of the injector
due to the application of high pressure fuel to the fuel supply line 18 is reduced.
[0039] Figures 2a and 2b show the injection process within a typical known injector 1. Like
features between Figures 1 and 2 are denoted by like reference numerals. The injector
in Figures 1 and 2 comprises an electromagnetic actuator arrangement 44 located above
a valve arrangement 50. A spacer component 52 is situated underneath the valve arrangement
50 and above the needle 12. The spacer 52 integrates the control chamber 22 and three
calibrated orifices (54, 56, 58) which allow operation of the injector.
[0040] The valve arrangement 50 comprises a valve stem portion 60 which carries an armature
62 at one end of the stem portion. The stem portion is slidable within a bore 64.
The valve stem portion carries a number of depressurisation grooves and, at the armature
end of the stem portion, there is a sealing face 66 which is engageable with a seat
68 at an end of the bore. When the sealing face is brought into contact with the seat
a contact making pressure seal is made. A valve spring 46 (not shown in Figures 2a-2b)
is located above the armature and acts to urge the sealing face into engagement with
its seat.
[0041] Within the spacer component 52 there is an injection supply orifice 58 (also referred
to as the nozzle path orifice or NPO), a control chamber discharge orifice 54 (also
referred to as the spill orifice or SPO) and a control chamber filling orifice 56
(also referred to as the inlet orifice or INO).
[0042] The operation of the injector will now be briefly described with reference to Figures
2a and 2b.
[0043] In Figure 2a, the valve arrangement 50 is closed and the sealing face 66 is engaged
with the seat 68. The control chamber 22 is therefore subjected to the pressure within
the common rail. The high pressure fuel exerts a force on the top of the needle 12
which exceeds the pressure of fuel acting on a pressure surface 70 of the needle 12.
The needle is therefore held closed such that there is no injection through the orifices
15.
[0044] In Figure 2b, the actuator 44 is energised and lifts the armature 62 such that the
valve arrangement 50 is in its open position in which the sealing face 66 lifts from
its seat 68. Fuel contained within the control chamber 22 now has a flow path through
the spill control orifice 54 (SPO) to a low pressure drain and fuel consequently flows
from the control chamber 22. Initially the pressure exerted on the top of the needle
12 by fuel within the control chamber 22 and the injector spring 30 exceeds the pressure
exerted on the pressure surface 70.
[0045] However, as soon as the pressure exerted by fuel on the pressure surface 70 exceeds
the spring force and the force exerted by fuel in the control chamber 22 then the
needle 12 lifts and injection of fuel through the orifices 15 commences as fuel flows
from the common rail through the nozzle path orifice 58 as in Figure 2b.
[0046] To stop injection, the electromagnetic actuator 44 is de-energised and the valve
spring 46 (not shown in Figure 2) closes the valve arrangement 50. High pressure fuel
passes from the supply line 18 through the control chamber filling orifice 56 (INO)
and the pressure rises within the control chamber 22 until injection ceases.
[0047] Figures 3 and 4 show the operation of a valve arrangement 100 in accordance with
an embodiment of the present invention. In Figures 3 and 4, like features between
Figures 1 to 4 are denoted by like features.
[0048] The valve arrangement 100 of Figures 3 and 4 comprises a valve stem portion 102 and
a valve head portion 104 located at one end of the valve stem portion 102. The valve
arrangement 100 is generally located within a valve guide 106. The valve guide comprises
a bore 108 which is open at a first end 110 and which opens into a valve groove 112
at a second end (111) of the bore (108).
[0049] Figure 3 shows the valve arrangement 100 in a closed configuration in which there
is no fuel flow path from the control chamber 22 to a low pressure drain (not shown).
It is noted that the cross sectional area of the valve head 104 varies such that in
the closed configuration of the valve arrangement 100 as shown in Figure 3 the valve
head 104 seats against the opening 110 of the valve guide 106 to form a seal.
[0050] Figure 4 shows the valve arrangement in an open configuration in which there is a
flow path 114 for fuel from the control chamber 22 through the spill orifice 54 to
the low pressure drain.
[0051] Instead of a valve spring as shown in Figure 1, the valve arrangement of Figures
3 and 4 comprises a biasing member 120 located at the end of the valve stem 102 remote
from the valve head 104, the biasing member being arranged to bias the valve arrangement
towards the closed configuration. The biasing member in Figures 3 and 4 comprises
a substantially planar elastic plate which is located within the valve groove 112.
[0052] The biasing member 120 is arranged such that in the closed configuration the pressure
exerted by fuel on the valve head 104 is substantially equal to the pressure exerted
on the elastic plate 120. In this manner the valve arrangement 100 is substantially
hydraulically balanced in the closed configuration and the valve is held closed against
small pressure variations by the elastic plate which exerts a force in a downward
direction (i.e. from the actuator arrangement towards the needle in the configuration
of Figure 3).
[0053] In Figure 4 the actuator arrangement 44 has been energised. The upwards force exerted
by the actuator arrangement 44 exceeds the downwards force from the elastic plate
120 and consequently the valve arrangement 100 has been lifted upwards into its open
configuration. The valve head 104 is no longer seated against the orifice 110 of the
valve bore 108 and the fuel flow path 114 to the low pressure drain has been opened
such that fuel can flow from the control chamber 22 and the needle 12 can lift from
its seat. It can be seen that the elastic plate 120 has deformed slightly (122) as
a result of the force exerted by the actuator.
[0054] When the actuator arrangement 44 is de-energised the elastic plate 120 regains its
previous substantially planar configuration and as a result closes the flow path by
bringing the valve head back to its seat 110. The pressure in the control chamber
22 then rises again as described above in relation to Figures 2a and 2b as fuel flows
into the control chamber via the INO 56.
[0055] It is noted that the volume 124 beneath the biasing member 120 is a fuel filled volume
that is connected to a back leak return passage (connection not shown in Figures 3
to 9) to allow the elastic plate to deform as required.
[0056] The elastic plate may comprise a steel plate. The steel plate is arranged to provide
a closing force for the valve member 106 that is sufficient such that the spring 46
shown in Figure 1 is not required. It is noted that once the spring 46 is removed
from the injector then there is more space available for the magnetic material within
the actuator (for example, the core member 44a of Figure 1 could be larger). The increase
in material within the actuator core member results in improved actuator performance
and therefore improved valve performance. It is also noted that once the spring 46
has been removed the stop member 47 can be simplified which reduces the cost of the
valve.
[0057] Typically the steel plate is designed to provide a force equal or higher to the previous
design in a range of 25 to 50 N according injector type. The use of a steel plate
(biasing member) in place of a wound spring improves the functionality of the valve.
Valve response times are improved compared to spring based arrangements and the initial
opening force from the actuator has a lower tolerance level which reduces the variation
between the performance of different valves in production.
[0058] Figures 5 to 8 show further embodiments of the present invention. It is noted that
in each of Figures 5 to 8 the valve arrangement is shown in the closed configuration.
Like numerals are used to denote like features in Figures 3 to 9.
[0059] In Figure 5 the substantially planar elastic plate of Figures 3 and 4 has been replaced
with a ridged plate 126. Figure 5 shows the second embodiment of the invention in
its closed configuration in which the pressures on the plate 126 and head 104 are
substantially equal. Providing ridges 128 in the plate alters the speed at which the
valve plate 126 can close the valve.
[0060] Figure 6 shows a third embodiment of the present invention in which the valve stem
portion 102 is formed from a portion of the biasing member 120. The biasing member
in Figure 6 comprises a substantially planar portion 130 and a stem portion 132 which
is formed integrally with the planar portion 130. The stem portion 132 comprises a
generally cylindrical section and carries a number of grooves 134 and ridges 136 on
its surface. The valve head 104 is located at one end of the stem portion 132.
[0061] As noted above in relation to Figure 5, the force applied by the valve plate (and
therefore the rate at which the valve closes) can be adjusted by providing a ridged
plate 126. It is noted however that there are limitations on the maximum thickness
of the ridge that can be used and also the location of the ridge on the plate. Figures
6 to 8 provide further embodiments of the present invention in which the stem portion
102 has been replaced with an extension (stem portion 132) of the planar portion 130
of the biasing member 120. The stem portion 132 provides greater flexibility in locating
the groove features which in turn provides greater flexibility in the force that the
biasing member can exert on the valve head 104.
[0062] Figures 7 and 8 are similar to each other. In these embodiments the biasing member
120 is formed into a stem portion 132 and the valve head 104 is of annular construction
which is arranged to be of complementary shape to a first part 138 of the stem portion
132 of the biasing member 120. In both Figures 7 and 8 the valve head 104 is retained
on the first part 138 of the stem portion 132 of the biasing member.
[0063] The stem portion in Figures 7 and 8 also comprises a second part 140 which carries
a number of grooves 134 and ridges 136 on its surface. The biasing member of Figures
7 and 8 also comprises a planar portion 130.
[0064] Figures 7 and 8 provide an alternative way of attaching the biasing element 120 to
the valve head 104. In Figures 3 to 6, the valve stem portion 102 or valve head 104
are welded to the biasing member 120. Due to the configuration of these embodiments
the bond surface is blind and the attachment process is consequently difficult to
control with lower cost production equipment.
[0065] In Figures 7 and 8 however the stem portion 132 protrudes through the annular valve
head 104 such that the stem portion is visible from the outside. This in turn allows
a crimping fixing method of attachment to be used which is cheaper and a more easily
controlled production process.
[0066] It is noted that Figures 6 to 8 reduce the mass contained within the valve arrangement
compared to Figures 3 to 5 and 9. The embodiments of Figures 6 to 8 therefore potentially
have faster valve response times.
[0067] Figure 9 provides a further embodiment of the present invention in which the control
orifices 54, 56 and 58 are integrated into the biasing member 120 instead of within
the spacer 52. The biasing member 120 is of lower thickness than the spacer 52 and
so the manufacturing time and manufacturing cost for producing the control orifices
is reduced.
[0068] It will be understood that the embodiments described above are given by way of example
only and are not intended to limit the invention, the scope of which is defined in
the appended claims. It will also be understood that the embodiments described may
be used individually or in combination.
1. A valve arrangement (100) for use in an injector, the valve arrangement arranged to
be moveable between an open configuration in which the valve arrangement provides
a flow path (114) for pressurised fuel from a control chamber of the injector to a
low pressure drain and a closed configuration in which the valve arrangement closes
the flow path, the valve arrangement comprising:
a valve guide (106) located within the injector, the valve guide comprising at least
a part of the flow path;
a valve head portion (104) arranged to close a first end (110) of the valve guide
when the valve arrangement is in the closed configuration;
a biasing member (120) arranged to bias the valve arrangement towards the closed configuration
;
wherein
the biasing member (120) comprises an elastic member located within the valve guide
and the biasing member defines a volume (124) within the valve guide, the arrangement
being arranged to be substantially hydraulically balanced when in the closed configuration.
2. A valve arrangement as claimed in Claim 1, wherein forces resulting from fuel pressure
within the valve guide on the valve head portion (104) are substantially equal to
forces resulting from fuel pressure within the valve guide on the biasing member (120),
the forces on the head portion and biasing member acting in substantially opposing
directions.
3. A valve arrangement as claimed in any preceding claim, further comprising a valve
stem portion (102) arranged to be located within the valve guide, the valve head portion
(104) being located at a first end of the valve stem portion (102) and the biasing
member (120) being located at a second end of the valve stem portion.
4. A valve arrangement as claimed in any preceding claim, wherein, in the closed configuration,
the biasing member (120) comprises a substantially planar elastic plate.
5. A valve arrangement as claimed in any one of Claims 1 to 3, wherein the biasing member
comprises a ridged plate (126).
6. A valve arrangement as claimed in any one of Claims 1 or 2, wherein the biasing member
comprises a substantially planar elastic portion (130) and a stem portion (132), the
valve head portion (104) being located at a first end of the stem portion and the
elastic portion being located at a second end of the stem portion.
7. A valve arrangement as claimed in Claim 6, wherein the stem portion is substantially
cylindrical and comprises a number of grooves (134).
8. A valve arrangement as claimed in Claim 6 or 7, wherein the valve head portion is
mounted at one end of the stem portion.
9. A valve arrangement as claimed in Claim 6 or 7, wherein the valve head portion is
of annular construction and the stem portion protrudes through the valve head portion.
10. A valve arrangement as claimed in any preceding claim, wherein the valve guide (106)
comprises a bore (108) which is open at the first end (110) and a valve groove (112)
at a second end (111) of the bore (108) remote from the first end (110), the biasing
member (120) being located within the valve groove.
11. A valve arrangement as claimed in Claim 10, wherein the valve groove (112) has a greater
cross sectional area than the bore (108).
12. A valve arrangement as claimed in Claim 10 or Claim 11, wherein the biasing member
forms a partition across the valve groove (112) such that the valve head portion (104)
and valve bore (108) are located on one side of the partition and the volume (124)
is formed on the other side of the partition.
13. A valve arrangement as claimed in Claim 12, wherein the volume (124) is filled with
fuel and is arranged to be in fluid communication with a fuel return back leak circuit.
14. An injector for use in the delivery of fuel to a cylinder of an internal combustion
engine, the injector comprising :
a body (10) provided with a bore (11);
a valve needle (12) slidable within the bore (11) of the nozzle body (10);
an actuator (44) ;
a fuel supply line (18) for supplying pressurised fuel to a control chamber (22) ;
a valve arrangement according to any one of Claims 1 to 14 actuable by the actuator
(44) for permitting fuel to flow from the control chamber (22) to a low pressure drain.
1. Eine Ventilanordnung (100) zur Verwendung in einem Injektor, wobei die Ventilanordnung
ausgebildet ist, zwischen einer offenen Konfiguration, in der die Ventilanordnung
einen Fließpfad (114) für unter Druck stehenden Kraftstoff von einer Steuerkammer
des Injektors zu einem Niederdruckauslass vorsieht, und einer geschlossenen Konfiguration
bewegbar zu sein, in der die Ventilanordnung den Fließpfad schließt, wobei die Ventilanordnung
aufweist:
eine Ventilführung (106), die sich in dem Injektor befindet, wobei die Ventilführung
zumindest einen Teil des Fließpfads aufweist;
einen Ventilkopfteil (104), der ausgebildet ist zum Schließen eines ersten Endes (110)
der Ventilführung, wenn die Ventilanordnung in der geschlossenen Konfiguration ist;
ein Biasing-Element (120), das ausgebildet ist zum Beeinflussen der Ventilanordnung
in die geschlossene Konfiguration;
wobei
das Biasing-Element (120) ein elastisches Element aufweist, das sich in der Ventilführung
befindet, und das Biasing-Element ein Volumen (124) innerhalb der Ventilführung definiert,
wobei die Anordnung ausgebildet ist, im Wesentlichen hydraulisch ausgeglichen zu sein,
wenn in der geschlossenen Konfiguration.
2. Ventilanordnung gemäß Anspruch 1, wobei Kräfte, die von einem Kraftstoffdruck innerhalb
der Ventilführung auf den Ventilkopfteil (104) resultieren, im Wesentlichen gleich
sind zu Kräften, die von einem Kraftstoffdruck innerhalb der Ventilführung auf das
Biasing-Element (120) resultieren, wobei die Kräfte auf den Kopfbereich und das Biasing-Element
im Wesentlichen in entgegengesetzte Richtungen wirken.
3. Ventilanordnung gemäß einem vorhergehenden Anspruch, die weiter einen Ventilschaftteil
(102) aufweist, der ausgebildet ist, sich innerhalb der Ventilführung zu befinden,
wobei sich der Ventilkopfteil (104) an einem ersten Ende des Ventilschaftteils (102)
befindet und sich das Biasing-Element (120) an einem zweiten Ende des Ventilschaftteils
befindet.
4. Ventilanordnung gemäß einem vorhergehenden Anspruch, wobei in der geschlossenen Konfiguration
das Biasing-Element (120) eine im Wesentlichen planare elastische Platte aufweist.
5. Ventilanordnung gemäß einem der Ansprüche 1 bis 3, wobei das Biasing-Element eine
geriffelte Platte (126) aufweist.
6. Ventilanordnung gemäß einem der Ansprüche 1 oder 2, wobei das Biasing-Element einen
im Wesentlichen planaren elastischen Teil (130) und einen Schaftteil (132) aufweist,
wobei sich der Ventilkopfteil (104) an einem ersten Ende des Schaftteils befindet
und sich der elastische Teil an einem zweiten Ende des Schaftteils befindet.
7. Ventilanordnung gemäß Anspruch 6, wobei der Schaftteil im Wesentlichen zylinderförmig
ist und eine Anzahl von Rillen (134) aufweist.
8. Ventilanordnung gemäß Anspruch 6 oder 7, wobei der Ventilkopfteil an einem Ende des
Schaftteils befestigt ist.
9. Ventilanordnung gemäß Anspruch 6 oder 7, wobei der Ventilkopfteil ringförmig ausgebildet
ist und der Schaftteil durch den Ventilkopfteil ragt.
10. Ventilanordnung gemäß einem vorhergehenden Anspruch, wobei die Ventilführung (106)
eine Bohrung (108), die an dem ersten Ende (110) offen ist, und eine Ventilnut (112)
an einem zweiten Ende (111) der Bohrung (108) entfernt von dem ersten Ende (110) aufweist,
wobei sich das Biasing-Element (120) innerhalb der Ventilnut befindet.
11. Ventilanordnung gemäß Anspruch 10, wobei die Ventilnut (112) eine größere Querschnittsfläche
als die Bohrung (108) hat.
12. Ventilanordnung gemäß Anspruch 10 oder Anspruch 11, wobei das Biasing-Element eine
Trennung über die Ventilnut (112) bildet derart, dass sich der Ventilkopfteil (104)
und die Ventilbohrung (108) auf einer Seite der Trennung befinden und das Volumen
(124) auf der anderen Seite der Trennung ausgebildet ist.
13. Ventilanordnung gemäß Anspruch 12, wobei das Volumen (124) mit Kraftstoff gefüllt
ist und ausgebildet ist, um in Fluidkommunikation mit einer Kraftstoffrücklaufleckschaltung
zu sein.
14. Injektor zur Verwendung bei einer Lieferung von Kraftstoff an einen Zylinder eines
Verbrennungsmotors, wobei der Injektor aufweist:
einen Körper (10) mit einer Bohrung (11);
eine Ventilnadel (12), die in der Bohrung (11) des Düsenkörpers (10) verschiebbar
ist;
einen Aktuator (44);
eine Kraftstoffzufuhrleitung (18) zum Liefern von unter Druck stehendem Kraftstoff
an eine Steuerkammer (22);
eine Ventilanordnung gemäß einem der Ansprüche 1 bis 14, die durch den Aktuator (44)
betätigbar ist, um zuzulassen, dass Kraftstoff aus der Steuerkammer (22) zu einem
Niederdruckauslass fließt.
1. Agencement de valve (100) à utiliser dans un injecteur, l'agencement de valve étant
agencé pour être déplaçable entre une configuration ouverte dans laquelle l'agencement
de valve assure un trajet d'écoulement (114) pour un carburant sous pression depuis
une chambre de commande de l'injecteur vers un drain à basse pression et une configuration
fermée dans laquelle l'agencement de valve ferme le trajet d'écoulement, l'agencement
de valve comprenant :
un guide de valve (106) situé à l'intérieur de l'injecteur, le guide de valve comprenant
au moins une partie du trajet d'écoulement ;
une portion formant tête de valve (104) agencée pour fermer une première extrémité
(110) du guide de valve quand l'agencement de valve est dans la configuration fermée
;
un élément de sollicitation (120) agencé pour solliciter l'agencement de valve vers
la configuration fermée ;
dans lequel
l'élément de sollicitation (120) comprend un élément élastique situé à l'intérieur
du guide de valve et l'élément de sollicitation définit un volume (124) à l'intérieur
du guide de valve, l'agencement étant agencé pour être sensiblement équilibré sur
le plan hydraulique lorsqu'il est dans la configuration fermée.
2. Agencement de valve selon la revendication 1, dans lequel les forces résultant de
la pression du carburant à l'intérieur du guide de valve sur la portion formant tête
de valve (104) sont sensiblement égales aux forces résultant de la pression du carburant
à l'intérieur du guide de valve sur l'élément de sollicitation (120), les forces sur
la portion de tête et sur l'élément de sollicitation agissant dans des directions
sensiblement opposées.
3. Agencement de valve selon l'une quelconque des revendications précédentes, comprenant
en outre une portion formant tige de valve (102) agencée pour être située à l'intérieur
du guide de valve, la portion formant tête de valve (104) étant située à une première
extrémité de la portion formant tige de valve (102), et l'élément de sollicitation
(120) étant situé à une seconde extrémité de la portion formant tige de valve.
4. Agencement de valve selon l'une quelconque des revendications précédentes, dans lequel,
dans la configuration fermée, l'élément de sollicitation (120) comprend une plaque
élastique sensiblement plane.
5. Agencement de valve selon l'une quelconque des revendications 1 à 3, dans lequel l'élément
de sollicitation comprend une plaque nervurée (126).
6. Agencement de valve selon l'une quelconque des revendications 1 ou 2, dans lequel
l'élément de sollicitation comprend une portion élastique sensiblement plane (130)
et une portion en tige (132), la portion formant tête de valve (104) étant située
à une première extrémité de la portion en tige et la portion élastique étant située
à une seconde extrémité de la portion en tige.
7. Agencement de valve selon la revendication 6, dans lequel la portion en tige est sensiblement
cylindrique et comprend un certain nombre de rainures (134).
8. Agencement de valve selon la revendication 6 ou 7, dans lequel la portion formant
tête de valve est montée à une extrémité de la portion en tige.
9. Agencement de valve selon la revendication 6 ou 7, dans laquelle la portion formant
tête de valve a une construction annulaire et la portion en tige se projette à travers
la portion formant tête de valve.
10. Agencement de valve selon l'une quelconque des revendications précédentes, dans lequel
le guide de valve (106) comprend un perçage (108) qui est ouvert à la première extrémité
(110) et une rainure de valve (112) à une seconde extrémité (111) du perçage (108)
éloignée de la première extrémité (110), l'élément de sollicitation (120) étant situé
à l'intérieur de la rainure de valve.
11. Agencement de valve selon la revendication 10, dans lequel la rainure de valve (112)
a une aire de section transversale plus grande que le perçage (108)
12. Agencement de valve selon la revendication 10 ou 11, dans lequel l'élément de sollicitation
forme une cloison à travers la rainure de valve (112) de telle façon que la portion
formant tête de valve (104) et le perçage de valve (108) sont situées sur un côté
de la cloison et le volume (124) est formé sur l'autre côté de la cloison.
13. Agencement de valve selon la revendication, dans lequel le volume (124) est rempli
de carburant et est agencé pour être en communication fluidique avec un circuit de
fuite et de retour de carburant.
14. Injecteur à utiliser pour la distribution de carburant à un cylindre d'un moteur à
combustion interne, l'injecteur comprenant :
un corps (10) doté d'un perçage (11) ;
une aiguille de valve (12) capable de coulisser à l'intérieur du perçage (11) du corps
de buse (10) ;
un actionneur (44) ;
un conduit d'alimentation de carburant (18) pour alimenter du carburant sous pression
à une chambre de commande (22) ;
un agencement de valve selon l'une quelconque des revendications 1 à 13, susceptible
d'être actionné par l'actionneur (44) pour permettre au carburant de s'écouler depuis
la chambre de commande (22) vers un drain à basse pression.