Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The invention relates to a pile-driviny ram com-
prising at least one combustion cylinder, a striker extending
into the combustion cylinder, a piston arranyed ln the cornbustion
cylinder and a fuel injector for suppl~iny fuel bet~Jeen the
impact surfaces of the piston and the striker.
Such a pile-driving ram is known from U.S. Patent
~! Specification 3,747,693. It is disclosed herein that the fuel
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of the striker in one direction, it being expected that the
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fuel will flow out across the whole or substantially the whole
impact surface. At the stroke of the piston on the striker the
fuel is atomized away from the impact surface of the striker
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n a direction towards a compression space surrounding the
striker so that it is mixed with the air of the compression
space in order to produce ignition of the fuel-air mixture.
¦ The time required for the fuel to flow out acros~ the impact
surface is considerably longer than the time interval between
¦ the injection and the stroke of the piston so that the spread
of the fuel as expected hardly occurs or is at least not achieved
perfectly. Particularly if the height of the piston movement
is small in the event of slight ground resistance, the impact
atomization is not sufficient to produce intimate contact
between air and fuel. As a result the fuel-air mixture in the
known ram does not ignite satisfactorily or is not ignited at all.
! 25 The invention has for its object to provide a
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~ pile-driving ram operating independently of the grsund resistance.
; According to the present invention there is provided a pile-
driving ram comprising at least one combustion cylinder, a striker extending
in~o the combustion cylinder, a piston arranged in the combustion cylinder
and fuel injector means for supplying uel between the impact surfaces of
the piston and the striker, said uel injector means being adapted to
spray fuel onto the impact surface of the striker at least at three rela-
tively spaced areas.
With this arrangement, the fuel atomization is improved so that it
is more intensively mixed with air and will ignite with greater certainty.
The fuel injector preferably comprises at least three nozzles dis-
tributed along the circumference of the combustion cylinder. This provides
a further improvement of the fuel distribution along the circumference of
the compression space.
In order to ensure that all areas of the impact surface struck
by fuel will receive equal quantities of fuel, the fuel injector may com-
prise at least three fuel pumps or at least one fuel pump with at least
three pump cylinders.
Dutch patent application 7215218 describes a pump having several
bores in order to choose a pump output at will. ~nly one of a plurality of
pumps is used, whilst one pump is employed for lubricating oil and the
other for fuel.
German Patent Application 1,936,529, laid up for public inspection,
relates to a direct injection in the air (nebulation). Fuel is not sprayed
at different areas onto an impact surface. The same applies to Dutch
Patent Specification 46,276.
In German Patent Publication 1,058,944 ~see the preamble, column
1, lines 31 to 40) it is disclosed that in the injection of two kinds of
fuel the starting fuel is injected by a second pump. In this literature
it is furthermore stated that neither the two kinds of ~uel are injected
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at different areas onto an impact surface, nor that different fuel injection
nozzles are used and nor that the two different fuels are simultaneously
injected.
Embodiments of the invention will be explained in the following
description with reference to drawings in which:
Figure 1 illustrates a survey of the pile-driving operation by
means of a ~ile-driver equipped with a ram in accordance with the in~ention;
Figure 2 is an enlarged vertical sectional view of a ram as shown
in Figure 1,
Figure 3 is an enlarged view of a preferred embodiment of a detail
; III in Figure 2 in a different position,
Figure 4 is an enlarged sectional view taken on the line IV-IV
in Figure 2,
Figure 5 is a sectional view corresponding with Figure 4 with a
diagram relating to a different embodiment of the ram in accordance with the
invention,
Figure 6 is a diagram relating to the fuel injector for ~he ram of
Figure 5, and
Figure 7 is a control-diagram for a ram as shown in Figure 5.
By means of a floating derrick 24 a pile-driver 27 is arranged on
a pile 21 to be driven into the soil 23 beneath the water 22. Said pile-
driver 27 comprises a guide frame 35 comprising a socket 25 surrounding the
pile 21, and two guide
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l stays 29 secured thereto. The pile-driver 27 furthermore
comprises a ram 8 guided by means of guide members 37 alony
the stays 29 and formed by a Diesel ram and a cap 31 beariny
. on the pile 21.
: ~ 5 Figure 2 shows that the ram 8 cimprises a combustion
: cylinder 3, a piston 1 operating as a hammer -therein and a
~ striker 2 bearing on the pile cap 31 and extending into the
; . combustion cylinder 3. The combustion cylinder 3 holds a tank 28
~- and has ports 26 for the air inlet and for the exhaust gases
and at least one fuel injection nozzle 30 of a fuel injector 6.
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~ :, . The piston 1 is sealed with respect to the combustion
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cylinder 3 by means of piston rings 19 and has a piston head 2n,
surrounded by an annular compression chamber 18. A conical
impact surface 4 of tbe striker 2 matches an engaging impact
; 15 surface 5 of the piston 1.
From Figure 4 it will be apparent that fuel is sprayed
I at a plurality of areas distrlbuted across the circumference
of the impact surface 4 onto said surface, for example, by
three jets 15 from the nozzle 30 so that three fuel zones 13
20 are formed. When the piston 1 strikes the striker 2, the fuel
is satisfactorily atomized and fans out like a curtain 12 in
the direction 17 away from the impact surface 4 into the lower
part 16 of a precombustion chamber 10 of the compression
: chamber 18 since a shallow, annular recess 11 adjacent the
impact surface 4 is provided in the striker 2. The fuel is then
ignited in the precombustion chamber 10 and the combustion
takes place slightly later mainly in the main combustlon
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chamber 32. This delay of the combustion process provides
a considerable improvement in the strikiny effect of the ram 8.
~l Owing to the finely divided particles the satisfactoril~
atomized fuel ignites readily, even with a small striking
path of the piston 1, but 0~7ing to lac~ of air in the precornbustion
chamber 10 the combustion i5 i~rformed slowl~.
Referring to Figurs 1 to 4 the ~uel injector 6 com-
prises only one pump with one nozzle 30, but the fuel injector 6
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shown in Figures 5 to 7 comprises two diametrically opposite
nozzles 30a and two diametrically opposite nozzles 30b
communicating with a pump 7a for a basic fuel 38 formed by
Diesel oil and a pump 7b for a substance 39 affecting the
combustion velocity respectively. The pumps 7a and 7b have,
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for each nozzle, a separate pump cylinder 9, the pump volume
of which is adjusted by an adjustable stop 33a and 33b
respectively. The positions of the stops 33a and 33b are
I determined by means of a control-member 41a and 41b respectively,
`¦ which regulates the supply and drainage of liquid 42 through
a control-slide 43a, 43b for a hydraulic cylinder 44a and 44b
respectively, as shown in the control-diagram of Figure 7.
The supply of fuel to the ram 8 results at each
; ! combustion in a stroke on the pile 21. The result of the
stroke is measured on the pile 21 by means of a feeler 45.
This feeler 45 may be formed by an optical meter which measures
l 25 the axial displacement 51 of the pile 21 resulting from each
stroke. The measured value 48 may be compared as the result
of a stroke in a comparator 46 with a datum value 49 prescribed
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by a proyramme 47, after which the difference siynal 50
energizes the control-members 41a and 41b. The diference
signals SO bring about a displacement of the stops 33a and
33b. The sense and the value of the displacements are
programmed in the control-member 41.
The substance 39, for example petrol, is supplied
~l as an accelerating agent to an extent proportional to the
tendency of the combustion to slow down. This occurs in
. accordance with a decreasing ground resistance. ~hen the
feeler 45 measures a large axial displacement 51, which signifies
a slight ground resistance, the pump 7b will supply a large
quantity of combustion-accelerating substance 39 to the ram 8.
If it is previously known that the ground resistance will be
heavy~, the tank 40 will contain, instead of petrol, a
substance 39, for example, benzene, decelerating the combustion
I velocity, which substance will then be supplied to the ram 8
i by the pump 7b according to a different programme/proportionally
; to the increase in ground resistance.
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