Ronald KUKLER: "Green Diesel" fuel injector, US Patent
#5484104


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**[rexresearch.com](../index.htm)**

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**Ronald KUKLER**

**Diesel Injector**

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**email:
ron.kukler@cleandieselcorp.com**   
[**http://www.tritonfoundation.org.au**](http://www.tritonfoundation.org.au)

**A
hydraulically operated, super-high pressure diesel
injector, installed in place of the standard injector,   
that produces 30% higher pressure, consumes 30% less fuel,
and reduces pollution. It is expected to retail for ~
$1000.**

Ron Kukler: "A 2-stage
hydraulic/electronic fuel delivery system creates extremely
high injection pressures of 160,000 psi compared to about
23,000 psi for traditional coon rail injection systems.
Fuel-injected at higher pressure results in a much cleaner
combustion process and a multitude of benefits evident in the
much-improved engine performance figures".

The system has been tested for
durability by Prof. Eric Milkins (Dept. Mechanical
Engineering, Melbourne University) for over 10,000 hours.

From www.greendieselcorp.com:
"Existing diesel common rail systems cost approx. 25% of
engine cost. Green Diesel's fuel system costs approx. 3% of
engine cost. We do not use a complicated and expensive high
pressure pump, and our electrics are simple.

Existing engine management systmes
will operate satisfactorily with Green Diesel's fuel system.
Millions of dollars and thousands of professional man-hours
have already been invested in our produce. We have engaged
university scholars, national award winning professionals,
engineers, doctors of mechanical engineering and experienced
technicians utilizing thermodynamic laboratory facilities,
dynamometers, flue-gas analyzers, particulate tunnel testing
and wolf sensors in conjunction with Melbourne University's
own Combustion Analysis in Real Time (CART) computer program.

Testing results to date: Dramatic
increase in horse power, dramatic increase in torque, band
width, and durability, reduction in specific fuel consumption
and in all pollutants, and dramatic reduction in cost,
simplicity, noise, vibration, weight and size.

![](injector.jpg)

![](green1.jpg)

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**US Patent # 5,484,104**   
**(January 16, 1996)**   
**US Cl. 239/87**

**Fuel Injector Pressurized by Engine
Cylinder Compression**

**Ronald Kukler**

**Abstract --** A fuel injector
is actuated by cylinder compression pressure acting against
the exposed face (31) of piston means (30, 35) to compress
fuel in high pressure chamber (45) in injector body (10). The
piston means (30, 35) moves against spring (36) and
controllable fuel pressure in low pressure chamber (37). The
high pressure chamber (45) communicates with injection orifice
(68) via delivery chamber (65) and non-return delivery valve
(56). Fuel delivery is regulated by varying fuel pressure in
low pressure chamber (37) and various means are disclosed for
controlling this pressure.

**References Cited:**   
U.S. Patent Documents --- 2230920 ~ 2333944 ~ 2389492 ~
2516690 ~ 4129256 ~ 4247044 ~ 4394856 ~ 4427151 ~ 4948044

**Foreign Patent Documents ---
GB2076073**

***Description***

**BACKGROUND OF THE INVENTION**

This invention relates to injecting
apparatus for injecting a fluid under pressure, e.g. fuel
injecting apparatus for internal combustion engines, apparatus
for injecting liquids, e.g. a catalyst into chemical reaction
vessels under pressure, and other apparatus for injecting a
dose of fluid.

Although the present invention is
applicable to any situation where a measured dose of fluid is
to be injected under pressure, it will be convenient to
describe the invention with particular reference to injecting
fuel into an internal combustion engine.

Fuel injectors used in internal
combustion engines, including both spark ignition and
compression ignition (or diesel) engines generally utilise an
external pump for supplying the fuel under sufficient pressure
to be injected into the engine cylinder. The timing of the
injection point in the engine operating cycle is determined by
externally controlling the operation of an injector valve by
mechanical means. One disadvantage of providing external
pumping and control is the need for the provision and
servicing of such external systems.

A general problem with injectors,
particularly ones supplied from an external pump, is lack of
responsiveness to any faulty condition in the associated
cylinder. For example, if a piston ring is broken, known
injectors will continue to inject fuel charges into the
cylinder. Thus fuel will be exhausted from the engine leading
to air pollution by exhausted unburnt fuel.

It has been proposed in the past to
utilise the build up of pressure within the cylinder of an
internal combustion engine during the compression stroke to
provide the motive force to compress fuel within the injector
body. For example, there has been proposed a fuel injector
which has a body, and a piston which is movable within the
body under the action of cylinder pressure. The movement of
the piston in the injector body causes an increase in pressure
of a fuel charge introduced into the body to a point where the
pressure enables a non-return valve associated with the
injector nozzle to open and allow the fuel to be injected
under pressure into the engine cylinder. Problems with this
device include difficulty and uncertainty in closing of the
valve leading to fuel continuing to dribble from the injector
after the desired cut off point, and also a general lack of
control over the operation of the injector.

U.S. Pat. No. 2,516,690 in the name
of French shows a fuel injector which utilises the associated
engine cylinder pressure to develop the pressure to inject the
fuel. The French apparatus has a simple spring biased
non-return valve at the injection nozzle so that the opening
and closing of the injection nozzle is solely controlled by
pressure differential and spring force. Some control of
pressure developed is provided by a non-return valve in an
outlet from the pumping chamber and an adjustable flow
restrictor downstream of the non-return valve. The French
apparatus has very limited ability to enable control of the
injector operation including timing, injection pressure,
volume of fluid injected, and degree of positiveness in
action.

U.S. Pat. No. 4,394,856 in the name
of Smith also shows an injector using engine cylinder pressure
to develop the injecting pressure. The Smith apparatus uses a
non-return valve as the injection valve. A solenoid operated
non-return valve is provided in the outlet from the pumping
chamber and an adjustable flow restrictor is provided in the
outlet line downstream of the non-return valve to enable
adjustment of the possible rate of flow when the solenoid
non-return valve is opened. In a similar manner to the French
US patent, the Smith injector has very limited ability to
enable control of the injector operation including timing,
injection pressure, volume of fluid injected, and degree of
positiveness in action.

U.S. Pat. No. 4,427,151 in the name
of Trenne shows a similar injector to the Smith injector
except that there is provision for adjusting the clearance
between the outlet valve member controlled by the solenoid and
its associated seat so that that adjustment enables some
control of the flow rate for fuel flowing out of the control
chamber. As with the French and Smith specifications, the
Trenne injector has limited degrees of control and limited
positiveness in operation, particularly the non-return
injector valve.

**SUMMARY OF THE INVENTION**

According to the present invention
there is provided an injecting apparatus for injecting a fluid
under pressure, the injecting apparatus including: a body,
piston means movable in the body under the action of
externally applied fluid pressure, the piston means being
operable to compress in a high pressure chamber, fluid to be
injected the piston means being movable against the action of
fluid pressure in a low pressure chamber whereby the movement
of the piston means is selectively controllable by controlling
the fluid pressure in the low pressure chamber, and an
injection valve and an associated injection orifice in fluid
communication with the high pressure chamber whereby high
pressure fluid from the high pressure chamber can be injected
through the injection orifice upon opening of the injection
valve.

Preferably the injection valve
which controls injection of high pressure fluid through the
orifice is selectively controllable in its operation. The
injection valve may include a valve member movable against the
action of fluid pressure in a control chamber, the fluid
pressure in the control chamber being selectively controllable
to control operation of the injection valve. The control
chamber is preferably in fluid communication with the low
pressure chamber whereby an increase in fluid pressure in the
low pressure chamber to resist movement of the piston means
also increases the fluid pressure in the control chamber
resisting opening of the injection valve.

In the preferred embodiment the
high pressure chamber communicates with the injection orifice
through a delivery chamber, the high pressure fluid from the
high pressure chamber being supplied to the delivery chamber
through a non-return delivery valve, the non-return delivery
valve being operable to close the delivery chamber and
maintain in the delivery chamber a charge of fluid stored
under pressure. Preferably the non-return delivery valve has a
valve member having a first stage of movement in which it
moves to stop communication from the pressure chamber to the
delivery chamber and a second stage of movement in which the
valve member after having completed its first stage of
movement allows limited pressure relief in the delivery
chamber so as to thereby reduce the fluid pressure upstream of
the injection valve.

The piston means is preferably
movable under the action of the externally applied fluid
pressure against the action of a main spring, the force
applied by the main spring at least in part determining the
externally applied fluid pressure necessary to initiate
movement of the piston means, the injecting apparatus further
including a delivery spring against the action of which the
injection valve moves to allow fluid injection through the
orifice, the strength of the delivery spring determining at
least in part the pressure of fluid in the high pressure
chamber necessary to open the injection valve to allow fluid
injection through injection orifice.

Preferably there is provided a
bleed path for high pressure fluid to bleed from the high
pressure chamber upon movement of the piston means by a
predetermined maximum extent, the opening of the bleed path as
a result of said predetermined maximum movement occurring
relieving fluid pressure in the high pressure chamber to an
extent sufficient to stop injection of fluid through the
injection valve.

The present invention also provides
an injecting system comprising an injecting apparatus
according to the invention, a fluid pressure relief path
through which fluid pressure in the low pressure chamber can
be controllably relieved to permit and control movement of the
piston means, and an associated fluid pressure governor means,
the governor means being selectively controllable to control
the fluid pressure in the low pressure chamber by selectively
preventing or progressively limiting relief of pressure from
the low pressure chamber through the fluid pressure relief
path in response to movement of the piston means. In this
injecting system, the governor means may include a flow
restriction means in the fluid pressure relief path to
selectively control the cross sectional area of the fluid
pressure relief path, the flow restriction means having an
associated drive means so as to drive the flow restriction
means to vary the cross sectional area of the relief path, the
governor means further including a back pressure valve located
in the fluid pressure relief path, downstream of the flow
restriction means, the back pressure valve being operative to
maintain a predetermined minimum back pressure in the fluid
pressure relief path by only opening when the predetermined
minimum back pressure is exceeded.

The fluid pressure relief path
preferably includes a pressure compensating means which
includes a restriction and varying means for varying the size
of the restriction in response to changes in fluid pressure
downstream thereof, the varying means being operative to
reduce the area of the restriction to maintain a predetermined
pressure downstream of the pressure compensating means. The
pressure compensating means may comprise a chamber which
communicates with the low pressure chamber, the pressure
compensating means further including a shuttle valve
responsive to the pressure differential between the fluid
pressure in that chamber and a point further downstream in the
fluid pressure relief path and being operative in response to
an increase in the pressure differential to reduce the area of
the restriction and thereby retard pressure relief from the
chamber to the point further downstream.

The injecting system may further
include a controllable damper means in communication with the
fluid pressure relief path, the damper means including a
movable damper member responsive to a pressure increase in the
fluid pressure relief path to yield so as to thereby relieve
pressure in the fluid pressure relief path, the damper means
further including an adjustable limiting means associated with
the movable damper member to controllably limit the extent of
yielding movement, the limiting means thereby effectively
determining the pressure relief provided by the damper means.
The movable damper member may comprise a resilient damper disc
which defines one wall of a chamber which is in communication
with the fluid pressure relief path, the limiting means
comprising a limiting stop which is adjustable so as to be
contacted by the damper disc.

The injecting system in another
embodiment may be characterised in that the fluid pressure
relief path includes a high speed solenoid valve operative to
open and close the fluid pressure relief path in response to
actuation signals, the governor means being located downstream
of the solenoid valve and being operative to adjustably limit
in continuous increments the flow of fluid through the fluid
pressure relief path.

Possible and preferred features of
the present invention will now be described with particular
reference to the accompanying drawings. However it is to be
understood that the features illustrated in and described with
reference to the drawings are not to be construed as limiting
on the scope of the invention. In the drawings:

**BRIEF DESCRIPTION OF THE
DRAWINGS**

**FIG. 1 shows a cross sectional
view through an injector according to the present invention,**

![](fig1-2.jpg)

**FIG. 2 shows a cross sectional
view through one possible arrangement of a governor or
accelerator for use in controlling operation of the
injector,**

**FIG. 3 is a cross sectional view
through an alternative construction of injector according to
the present invention,**

![](fig3.jpg)

**FIG. 4 is a cross sectional view
through the rear portion of a further possible construction
of injector showing various means for enabling control of
the injector operation,**

![](fig456.jpg)

**FIG. 5 is a plan view of the
detailed section marked "A" in FIG. 4, and**

**FIG. 6 is a sectional view along
the line VI--VI in FIG. 4.**

**DESCRIPTION OF THE PREFERRED
EMBODIMENT**

Referring to FIG. 1, the injector
includes a body 10 which comprises a front body part 11 which
can for example have a threaded end 12 for engagement in a
threaded port associated with an engine, and a rear body part
13. An inlet 15 is provided in the body 10, the inlet 15
having a non-return valve 16 operated by spring 17. In use,
fuel is supplied or induced under low pressure into the inlet
15 sufficient to overcome the action of spring 17. The
strength of spring 17 is not critical. The fuel pressure can
be relatively low so that high pressure fuel lines are not
required.

An outlet 20 has an associated
non-return valve 21 acting by means of spring 22, the strength
of which is not critical. With this arrangement, fuel can
continuously be pumped or induced under low pressure into
inlet 15, through passage 25 and out through outlet 20. This
continuous fuel flow can provide cooling although
supplementary cooling could be provided.

The injector includes a low
pressure piston 30 slidable in the front body 11 when engine
cylinder pressure acts on the front face 31. Compression ring
32 and oil scraper ring 33 are provided for conventional
purposes.. Screwed to the low pressure piston 30 is a high
pressure piston 35. The piston assembly 30, 35 moves within
the body 10 against the action of main spring 36. The force
applied by main spring 36 determines, in part, whether the
piston assembly 30, 35 will move under the action of cylinder
pressure on face 31. Also, the main spring 36 is located in a
low pressure chamber 37 which is in fluid communication
through space 38 with the passage 25 and through valve 21 with
the outlet 20 so that the fluid pressure in low pressure
chamber 37 resisting movement of the piston assembly 30, 35
can be relatively low, subject to control to be described
later.

A possible variation of the
preferred construction illustrated and described is the
replacement of the main spring 36 with a pneumatic or other
biasing means.

The high pressure piston 35 has an
extension 40 of relatively small cross sectional area which
travels within a bore 41 provided within a high pressure body
42. The high pressure body 42 comprises a base section 43 and
a high pressure barrel 44 in which the extension 40 travels.
The base section 43 and high pressure barrel 44 are secured
together and define a high pressure chamber 45 in which fuel
is compressed to high pressure by the extension 40 of the high
pressure piston 35. Non-return valve 46 operated by a spring
47 allows fuel to enter the high pressure chamber 45 from the
passage 25 upon retraction of the high pressure piston
extension 40 in the bore 41. The strength of spring 47 is not
critical.

In the extension 40 there is
provided a bleed bore 50 and extending through the high
pressure barrel 44 is a bleed bore 51 which opens into the low
pressure chamber 37. If the stroke of the piston assembly 30,
35 is sufficient for the bleed bore 50 to align with the bleed
bore 51, the fuel within the high pressure chamber 45 is
immediately placed in communication with the low pressure
chamber 37 and the fuel pressure in high pressure chamber 45
will immediately drop so that there will be insufficient
pressure for fuel injection to continue as will be described
later. Thus the longitudinal separation between the bleed bore
50 and the bleed bore 51 effectively defines the maximum fuel
charge that can be injected during one stroke of the piston
assembly 30, 35 and this, in turn, effectively limits the
speed of running of the associated engine to a predetermined
maximum determined by the maximum fuel charge.

Running longitudinally through the
extension 40 of the high pressure piston 35 is a fuel passage
55 along which pressurised fuel from the high pressure chamber
45 travels as the piston assembly 30, 35 moves under the
action of the cylinder pressure. The fuel passes a non-return
delivery valve 56 which is shown resting against shoulder 57
under the action of spring 58. In operation, high pressure
fuel moves valve 56 away from shoulder 57 against the action
of spring 58. Fuel flows past the valve 56 only when it has
moved sufficiently for the shoulder 59 of the valve to move
past the end of passage 60 formed on the inside surface of the
high pressure piston 35. With this arrangement, when delivery
valve 56 is closing, fuel flow past the valve 56 is stopped
when the shoulder 59 reaches the end of the passage 60, after
which the valve 56 continues to move by a further limited
extent until the valve 56 reaches shoulder 57. This continued
movement of valve 56 after the valve has closed off fuel flow
relieves pressure on the downstream side of the valve 56 for a
purpose which will be described later.

The low pressure piston 30 has a
delivery chamber 65 into which high pressure fuel is
introduced through bore 66 provided in the spacer 67. At
forward end of the delivery chamber 65 is a delivery orifice
68 provided in an insert 69. The orifice 68 is shown closed by
needle type delivery valve 70 which seats against the insert
69 under the action of delivery spring 71. When the pressure
of fuel in the delivery chamber 65 is sufficiently great, the
needle valve 70 moves against the action of delivery spring 71
and opens the orifice 68 and fuel is injected through the
orifice 68 into the associated engine cylinder. The
commencement of injection through orifice 68 causes an
immediate drop in fuel pressure in delivery chamber 65 and the
needle valve 70 will tend to close the orifice 68 again. This,
in turn, will allow pressure in delivery chamber 65 to rise
and again open needle valve 70. This process continues so that
the needle valve 70 opens and closes the orifice 68 at high
speed. This action is known as "buzzing" of the delivery
needle valve 70 and causes the fuel to be injected through
orifice 68 in waves and this is believed to improve fuel
combustion efficiency.

The needle valve 70 has a shank 75
which moves within a guide 76. The end 77 of the shank 75
remote from the delivery orifice 68 closes a control chamber
78. Control chamber 78 communicates through (aligned) bores
79, 80 provided in the spacer 67 and low pressure piston 30
respectively and through the space 81 around the outside of
the low pressure piston 30 with the low pressure chamber 37.
Thus the control chamber 78 is normally in communication with
low pressure fuel allowing the needle valve 70 and shank 75 to
move away from the insert 69 to open the orifice 68 under the
pressure of fuel in the delivery chamber 65.

Referring to FIG. 2, there is shown
an accelerator or governor means which enables control of the
flow of fuel on the downstream side of the injector. In
particular, in use, the governor means shown in FIG. 2
comprises a body 85 having a bore 86 which is in communication
with the outlet 20 of the injector. The downstream end of the
bore 86 is provided with a chamfered seat 87. Longitudinally
selectively movable within the bore 86 is a governor 90 which
has a complementary chamfered shoulder 91 which can close
against seat 87 to completely close bore 86. The governor 90
has a shank 92 which extends into the bore 86 and is a close
fit within the bore. The shank 92 has a groove 93 which tapers
from the shoulder 91 to the upstream end 94 of the shank 92.
The fuel can flow into the bore 86 along the groove 93 and
between the shoulder 91 and seat 87 when the governor 90 is
retracted longitudinally in the direction of arrow A. If the
governor 90 is retracted only slightly from the seat 87, flow
along the groove 93 is significantly restricted since the fuel
must flow through the shallowest end of the groove 93 where
the seat 87 meets the bore 86 at point 95. If the governor 90
is retracted further in the direction of arrow A, greater flow
past point 95 is possible because of the deepening of the
groove 93 towards the end 94. Thus the selective retraction
and insertion of the governor 90 from and into the bore 86
enables control of the pressure in low pressure chamber 37 of
the injector, which in turn, can control the stroke of the
piston assembly 30, 35. If the governor 90 is moved to contact
the shoulder 91 against the seat 87, the fuel flow through
outlet 20 of the injector is prevented and this will
hydraulically lock the piston assembly 30, 35 against movement
by blocking the pressure relief path for fuel from low
pressure chamber 37.

The movement of the governor 90 in
FIG. 2 can be achieved by any suitable means such as a
mechanical adjustment of the position of governor 90.
Alternatively the governor 90 could be moved by a DC electric
motor or linear motor enabling electronic control of the fuel
injection. In this way, it is possible to infinitely vary the
fuel injection by controlling governor 90 in a continuous
manner, thereby controlling continuously the low pressure side
of the injector which in turn enables control of the point in
an operating cycle at which movement of the piston assembly
30, 35 is allowed to commence. In general terms, the hydraulic
control of the low pressure side of the piston assembly 30, 35
of the injector enables precise control of the point of
commencement of the stroke of the piston assembly 30, 35 which
controls the amount of fuel injected, up to a maximum charge
determined by the spacing of the bleed bore 50 and 51.

In operation of the injector in an
internal combustion engine, the increasing pressure on the
front face 31 of the low pressure piston 30 during the
compression state of the engine will tend to move the piston
assembly 30, 35 against the action of both the main spring 36
and the fluid pressure in chamber 37. If the pressure relief
from the low pressure chamber 37 through outlet 20 is
permitted, the piston assembly 30, 35 retracts to compress
fuel in high pressure chamber 45. The fuel flows through fuel
passage 55, past delivery valve 56 and into delivery chamber
65. The pressure in chamber 65 causes the needle valve 70 to
open against the action of both delivery spring 71 and the
pressure in low pressure chamber 37 which, in turn, is in
communication with control chamber 78 so that fuel injection
through orifice 68 commences.

Initially, fuel will be injected in
relatively large droplets since the pressure in the engine
cylinder is still relatively low. However, in the case of a
compression ignition engine, immediately ignition of the fuel
in the cylinder occurs, there is a rapid increase in cylinder
pressure which acts on face 31 of the piston 30. This pressure
jump immediately causes a multiplication of the fuel injection
pressure so that the fuel being injected through orifice 68 at
a greatly increased pressure will emerge in much smaller
droplets which improves the combustion efficiency. The initial
injection pressure jump may be from 4000 psi to 25000 psi. The
ratio of injection pressure to input pressure may be between
6:l and 12:1.

It is possible to control the
proportion of the total fuel charge which is injected at the
initial relatively low pressure by adjustment of the strengths
of the main spring 36 and the delivery spring 71. For example,
increasing the strength of the main spring 36 retards the
point of movement of the piston assembly 30, 35 thus delaying
the commencement of injection and reducing the proportion of
the fuel which is injected during the initial low pressure
injection stage prior to ignition. By adjustment of these
spring forces, it is possible to affect the efficiency of
combustion and hence control emissions, e.g. for different
cylinder sizes. The ratio of the high and low pressures of
injection is also controllable.

The maximum fuel charge is
determined by the spacing of the bleed bores 50, 51 which
effectively also provides a maximum engine speed limiter. In
particular, when the bleed bores 50 and 51 align, the fuel
pressure in the high pressure chamber 45 is immediately
relieved through the bleed bores 50, 51 and this pressure drop
is immediately conveyed to the delivery chamber 65 so that the
needle valve 70 immediately closes.

The external control of the
pressure relief through the outlet 20 of the injector, e.g. by
means of the governor means shown in FIG. 2, not only controls
the point of opening movement of the piston assembly 30, 35
but also controls the low pressure side in chamber 37 during
an injection operation. If the pressure relief through outlet
20 is retarded, the movement of piston assembly 30, 35 is
limited by the relief of pressure in the low pressure chamber
37 and also the opening movement of the needle valve 70 is
resisted by the retarded relief of pressure in control chamber
78 acting against face 77 of the shank 75 of the needle valve
70. Thus low pressure side hydraulic lock up controls
termination of the fuel injection operation. Alternatively,
the termination of the injection operation occurs when the
maximum fuel charge is injected and the bleed bores 50, 51
align and cause an immediate high pressure side pressure drop.
In either case, the delivery needle valve 70 closes the
orifice 68. The delivery valve 56 also will immediately move
towards its closed position under the action of spring 58 so
that the shoulder 59 reaches the end of passage 60 thus
closing off communication between the high pressure chamber 45
and the delivery chamber 65. Because the delivery valve 56
continues to move beyond the point at which shoulder 59
reaches the end of passage 60, the fluid pressure in delivery
chamber 65 can continue to be relieved preventing opening of
needle valve 70 until high pressure is again built up in
delivery chamber 65. These combined actions of hydraulic lock
up of the low pressure side or high pressure side pressure
relief, together with the two stage movement of the delivery
valve 56 ensure immediate and positive termination of the fuel
injection.

The injector shown in FIG. 3 is in
most respects the same as the injector shown in FIG. 1 and the
same reference numerals are used for corresponding parts.

Different features in FIG. 3
include the modified needle valve 70 which, instead of a
conical tip, includes a blunt nose portion 70a which
substantially fills the "sack" 72 which is a small space
immediately upstream of the orifice 68. The fuel remaining in
the sack 72 in prior injectors was sometimes a cause of
continued fuel introduction into the cylinder after the
desired cut off point.

Also in FIG. 3, the spacer 67 is
provided with a non-return valve 100 arranged to allow the
flow from the control chamber 78 to the low pressure chamber
37 but preventing a shock loading at any time from being
transmitted into the chamber 78.

In FIG. 3, the inlet 15 is shown in
a different location with a relatively small inlet valve 16
allowing fuel under low pressure to pass from the inlet 15 to
an inlet manifold 102 which encircles the body 10 and enables
fluid to pass from the annular manifold space 103 through
passages 104 to the low pressure chamber 37.

Also in FIG. 3, there is provided a
high speed solenoid 105 having an associated valve member 106
arranged to selectively close the outlet 20. The solenoid 105
can be energised under the control of an electrical switching
means 107 by means of which the time of commencement of
injection is controllable and also the length of the period of
injection is also controllable. In particular, the opening of
the valve 106 by solenoid 105 under the control of the control
means 107 enables the injection to commence. Prior to opening
of the valve 106 the piston assembly 30, 35 is effectively
hydraulically locked against movement. Similarly, closing of
the valve 106 will again lock the piston assembly 30, 35
against movement thereby terminating the injection.

Downstream of the valve 106 there
is an outlet port 110 through which pressure relieving flow
can take place when the valve 106 is open. Associated with the
outlet port 110 or downstream thereof there is preferably
provided an adjustable flow restriction means to enable
selective control of the rate of pressure relieving flow
through the outlet port 110, the adjustable flow restriction
comprising a governor arrangement such as shown in FIG. 2.

FIG. 4 showns an alternative
injector control arrangement located at the rear body 13 of
the injector, although the control arrangement may be a
separate unit connected in the fluid pressure relief path from
the low pressure chamber 37. In the embodiment in FIG. 4,
pressure relief from the chamber 37 is provided through a
fluid pressure relief path comprising a first chamber 120
which communicates with an intermediate chamber 121 through a
pressure compensating means 122 comprising a restriction 123
(FIG. 5) shown in the form of a slot provided within sleeve
124. Inside the sleeve there is provided a shuttle valve
member 125 having a head 126 which progressively closes or
opens the slot 123 as the shuttle valve 125 moves within the
sleeve 124.

The fluid pressure relief path also
includes a downstream low pressure chamber 130. The fluid
pressure in chamber 130, together with the force of spring 131
opposes movement of the shuttle valve 125 under the influence
of fluid pressure from the chamber 120 passed to the
intermediate chamber 121. However if the pressure differential
between intermediate chamber 121 and low pressure chamber 130
rises sufficiently, the shuttle valve 125 will move and the
head 126 will restrict the pressure relieving flow through the
slot 123 thereby enabling the pressure in the intermediate
chamber 121 to reduce by means of flow to low pressure chamber
130.

Interposed in the fluid pressure
relief path between the intermediate chamber 121 and the low
pressure chamber 130 is a selectively controllable flow
restriction means 135 which comprises a needle valve 136
having a tapered nose portion 137 located in the passage 138
extending between intermediate chamber 121 and low pressure
chamber 130. The needle valve 136 is selectively movable by
means of electrical or mechanical control means 139 so as to
enable selective control of the rate of pressure relief
through the passage 138. This, in turn, enables control of the
injection rate.

Downstream of the flow restriction
means 135 there is a non-return valve 140 which functions to
maintain a minimum back pressure determined by the force of
spring 141 which is a function of the spring itself and the
position of adjustable seat 142 for the spring 141. At low
idle speeds of an associated engine, the valve 140 determines
the minimum back pressure. At higher engine speeds, the valve
140 remains open substantially all of the time.

The system shown in FIG. 4 also
provides a controllable damper means 150, illustrated more
clearly in FIG. 6. The damper means 150 includes a movable
damper member 151 illustrated as a damper disc mounted in a
damper chamber 152 which is in communication through duct 153
with the intermediate chamber 121. The damper disc 151 yields
resiliently upon an increasing pressure in the intermediate
chamber 121. There is an adjustable stop member 155 which is
adjustable by means of set screw 156 to enable selective
setting of the limit of resilient movement of the damper disc
151. By adjusting the position of the stop member 155, the
idle setting or speed of an associated engine can be
effectively controlled. In particular, a relatively large gap
between the stop member 155 and the damper disc 151 enables a
larger stroke of the piston assembly 30, 35 before the other
flow limiting means or pressure relief limiting means become
effective, thereby enabling a higher idle speed to be set.

The embodiment of the injector
system shown in FIGS. 4 to 6 and described above provides a
great deal of control over the operation of the injector,
including control over the timing of the start and end of
injection, the rate of injection, idle speed, and even
variation in rate of injection within a single injection
cycle. The greater degree of control that is possible makes
the injector system particularly suitable for direct fired
internal combustion engines.

The construction and arrangement of
the injectors and associated controllers illustrated and
described with reference to the drawings enables accurate and
repeatable control of the point of commencement of the
injection, accurate and repeatable control of the charge of
liquid which is injected during each injection cycle, and
accurate and repeatable point of termination of the injection.
The three stage positive termination of injection makes the
injector suitable for high speed two stroke engines.

Automatic pollution control is one
benefit of using the cylinder pressure to develop the
injection pressure. In particular, if the engine cylinder
develops a fault, such as a broken piston ring, leading to a
drop in pressure in the cylinder, the pressure drop will
immediately prevent or at least reduce the charge of fuel that
the injector will introduce into that cylinder. Thus the
engine will exhaust less unburnt fuel compared to an engine
where a full charge continues to be injected into a faulty
cylinder. This compensation also occurs in the case of normal
wear of components so that pollution reduction and wear
compensation results.

Another benefit of the injector is
that it provides automatic timing adjustment. In particular,
as an associated engine increases in running speed, ideally,
the commencement of injection should be advanced in the
operating cycle since the fuel needs a predetermined minimum
time to burn completely regardless of the speed of the engine.
With the injector of the present invention, as the engine
piston commences the compression cycle, there is a faster
build up of pressure in the cylinder at higher engine speeds
since the heat is not escaping as quickly from the engine as
at lower speeds. This more rapid increase in pressure will
automatically advance the commencement of injection to earlier
points in the engine cycle. This advancement can be in excess
of 15.degree. from initial setting to the point of injection
at maximum engine speed.

A further advantage of the
preferred injectors described and illustrated is the lowered
average combustion overall pressure which results from the new
combustion mode. This in turn can lead to the use of lighter
components. The "new combustion mode" results from the
different phases of the combustion of the fuel. If a pressure
versus time graph for a conventional engine were shown, the
graph rises sharply to a peak and drops rapidly. With the
injectors of the preferred embodiment, the control of the
injected droplet sizes and the injection pressures enables
control of the combustion process so that the pressure time
graph can have a relatively flat plateau so that the area
under the graph which relates to the work can be the same as
conventional engines but the lower maximum pressure leads to
less stress in the motor and the ability to use smaller or
lighter components.

Because the injectors described and
illustrated requires low levels of lubrication due to the
absence of bearing components, the injectors will function
with a no wax diesel fuel making it possible to work in cold
climates. With careful material selection, LPG can be directly
used.

A further advantage of the
preferred injector construction and operation is the ability
to automatically prime the injector for a subsequent
operation. By closing the external governor means, there is a
hydraulic lock up of the low pressure side, and fuel will be
stored in the delivery chamber 65 since the fuel cannot be
released through the orifice 68 or through the delivery valve
56. Thus, when the associated engine is to be re-started, the
first compression cycle of the associated engine will enable
fuel under pressure in the delivery chamber 65 to be injected
for commencing normal operation of the engine.

In the particular construction of
injectors shown in the drawings, metal to metal contacts are
used to provide sealing between immovable parts. For example,
the front body 11 and rear body 13 are connected together with
metal to metal contact between a sharp step 96 provided on the
rear body 13 and a chamfered face 97 provided on the front
body 11. This also applies to connections between the spacer
67 and the low pressure piston 30, between the spacer 67 and
the high pressure piston 35, and between the high pressure
barrel 44 and the base section 43. These connections are
modified "Lenz ring seats" and provide good sealing under high
pressures.

The valves, including the inlet
valve 16, outlet valve 21, non-return valve 46, delivery valve
56 and the needle valve 70 preferably have sealing contact
between the valve members and associated seats with an
internal angle less than 90.degree., and preferably at about
60.degree.. For example, the included angle in the point of
the needle valve 70 is preferably about 60.degree.. This
relatively shallow angle of seating has been found to provide
good sealing at a wide range of fluid pressures.

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