U.S. patent application number 11/722414 was filed with the patent office on 2009-03-19 for diesel pile hammer.
This patent application is currently assigned to DELMAG GMBH & CO. KG. Invention is credited to Matthias Heichel, Stefan Mewes.
Application Number | 20090071672 11/722414 |
Document ID | / |
Family ID | 36169102 |
Filed Date | 2009-03-19 |
United States Patent
Application |
20090071672 |
Kind Code |
A1 |
Heichel; Matthias ; et
al. |
March 19, 2009 |
DIESEL PILE HAMMER
Abstract
The invention relates to a diesel pile hammer (10) which
comprises a cylinder (12), a piston (14) slidably mounted inside
the cylinder (12), and an impact piece (16) slidably mounted inside
the cylinder (12), said impact piece being arranged below the
piston (14) in the operating position of the diesel pile hammer
(10). A working compartment (32) is axially delimited by a face
(36) of the impact piece (16) lying inside the cylinder (12) and a
face (46) of the piston (14). A fuel supply device (52, 55, 62, 68)
feeds a defined amount of fuel, especially diesel oil, to said
working compartment with every working cycle. The fuel supply
device (52, 55, 62, 68) is configured to inject the fuel into the
working compartment (32) of the cylinder (12) optionally in a first
mode of injection as an atomized fuel spray (76) or in a second
mode of injection as a fuel jet (74) or in a third mode of
injection both as an atomized fuel spray (76) and as a fuel jet
(74).
Inventors: |
Heichel; Matthias;
(Babenhausen, DE) ; Mewes; Stefan; (Reutlingen,
DE) |
Correspondence
Address: |
FACTOR & LAKE, LTD
1327 W. WASHINGTON BLVD., SUITE 5G/H
CHICAGO
IL
60607
US
|
Assignee: |
DELMAG GMBH & CO. KG
Esslingen
DE
|
Family ID: |
36169102 |
Appl. No.: |
11/722414 |
Filed: |
December 1, 2005 |
PCT Filed: |
December 1, 2005 |
PCT NO: |
PCT/EP05/12791 |
371 Date: |
October 21, 2008 |
Current U.S.
Class: |
173/209 ;
173/135 |
Current CPC
Class: |
E02D 7/125 20130101 |
Class at
Publication: |
173/209 ;
173/135 |
International
Class: |
E02D 7/12 20060101
E02D007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2004 |
DE |
10 2004 062 043.1 |
Claims
1. A diesel pile hammer comprising a cylinder, a piston slidably
guided in the cylinder, an impact piece that is slidably guided in
the cylinder and in the operating position of the diesel pile
hammer is arranged below the piston, a working compartment which is
axially delimited by an end face, located inside the cylinder, of
the impact piece and an end face of the piston, a fuel supply
device through which a predefined amount of fuel, can be introduced
into the working compartment with every working cycle, wherein the
fuel supply device is constructed in such a way that the fuel is
injected into the working compartment in a first mode of injection
as an atomised fuel mist and in a second monde of injection as a
fuel jet.
2. The diesel pile hammer of claim 1, wherein the fuel supply
device designed in such a way that the fuel mist of the first mode
of injection flows into the working compartment in the vicinity of
the end face of the impact piece substantially vertically to the
direction of movement of the piston.
3. The diesel pile hammer of claim 1, wherein the fuel supply
device is designed in such a way that the fuel jet of the second
mode of injection obliquely strikes the piston-side end face of the
impact piece.
4. The diesel pile hammer of claim 1, wherein the fuel supply
device comprises at least one high pressure injection nozzle and at
least one low-pressure injection nozzle, to which, via one pipe in
each case and by way of at least one fuel pump, of which the inlet
communicates with a fuel tank, the predefined amount of fuel can be
supplied with every working cycle of the diesel pile hammer.
5. The diesel pile hammer of claim 4, wherein at least one fuel
pump of the fuel supply device is constructed in such a way that
the amount of fuel supplied to a high-pressure injection device in
each case and the amount of fuel supplied to a low-pressure
injection device in each case can be adjusted.
6. The diesel pile hammer of claim 4, wherein the fuel pump can be
controlled or actuated by way of the dropping piston.
7. The diesel pile hammer of claim 4, wherein the fuel supply
device is constructed in such a way that it supplies the
high-pressure injection nozzle with a minimum amount of fuel with
every working cycle.
8. The diesel pile hammer of claim 1, wherein the end face of the
piston delimiting the working compartment is stepped by a
circumferential, radially external step.
9. The diesel pile hammer according to claim 1, wherein during a
third mode of injection, the fuel is injected into the working
compartment of the cylinder as both an atomised fuel mist and as a
fuel jet.
10. The diesel pile hammer of claim 4, wherein the predefined
amount of fuel supplied with every working cycle of the diesel pile
hammer is adjustable.
11. The diesel pile hammer of claim 2, wherein the fuel supply
device is designed in such a way that the fuel jet of the second
mode of injection obliquely strikes the piston-side end face of the
impact piece
12. The diesel pile hammer of claim 2, wherein the fuel supply
device comprises at least one high pressure injection nozzle and at
least one low-pressure injection nozzle, to which, via one pipe in
each case and by way of at least one fuel pump, of which the inlet
communicates with a fuel tank the predefined amount of fuel can be
supplied with every working cycle of the diesel pile hammer.
13. The diesel pile hammer of claim 3, wherein the fuel supply
device comprises at least one high pressure injection nozzle and at
least one low-pressure injection nozzle, to which, via one pipe in
each case and by way of at least one fuel pump, of which the inlet
communicates with a fuel tank the predefined amount of fuel can be
supplied with every working cycle of the diesel pile hammer.
14. The diesel pile hammer of claim 12, wherein at least one fuel
pump of the fuel supply device is constricted in such a way that
the amount of fuel supplied to a high-pressure injection device in
each case and the amount of fuel supplied to a low-pressure
injection device in each case can be adjusted.
15. The diesel pile hammer of claim 5, wherein the fuel pump can be
controlled or actuated by way of the dropping piston.
16. The diesel pile hammer of claim 5, wherein the fuel supply
device is constructed in such a way that it supplies the
high-pressure injection nozzle with a minimum amount of fuel with
every working cycle.
17. The diesel pile hammer of claim 6, wherein the fuel supply
device is constricted in such a way that it supplies the
high-pressure injection nozzle with a minimum amount of fuel with
every working cycle.
18. The diesel pile hammer of claim 2, wherein the end face of the
piston delimiting the working compartment is stepped by a
circumferential, radially external step.
19. The diesel pile hammer of claim 13, wherein the end face of the
piston delimiting the working compartment is stepped by a
circumferential, radially external step.
20. The diesel pile hammer of claim 4, wherein the end face of the
piston delimiting the working compartment is stepped by a
circumferential, radially external step.
Description
[0001] The invention relates to a diesel pile hammer comprising
[0002] (a) a cylinder,
[0003] (b) a piston slidably guided in the cylinder,
[0004] (c) an impact piece that is slidably guided in the cylinder
and in the operating position of the diesel pile hammer is arranged
below the piston,
[0005] (d) a working compartment which is axially delimited by an
end face, located inside the cylinder, of the impact piece and an
end face of the piston,
[0006] (e) a fuel supply device through which a predefined amount
of fuel, in particular diesel oil, can be introduced into the
working compartment with every working cycle.
[0007] Diesel pile hammers of this type, which are also called
diesel rams, are used in particular in foundation working in the
building industry to drive home all kinds of piles, such as
concrete piles, iron girders, sheet piling elements or the like,
into a subsoil.
[0008] To start a diesel pile hammer of this type the piston is
pulled upwards with the aid of a release device and is released at
a specific height, whereupon it drops down under the influence of
gravity. On dropping, the piston actuates a fuel pump, whereby one
or more injection nozzle(s) is/are supplied with fuel, in
particular diesel oil, which nozzles inject the fuel into the
working compartment of the cylinder.
[0009] As the piston drops the air situated in the working
compartment of the cylinder is compressed and consequently heated
in such a way that the fuel/air mixture present in the working
compartment ignites, whereupon it combusts in the manner of an
explosion.
[0010] The explosive energy released in the process on the one hand
throws the piston upwards again for a new working cycle and on the
other hand drives the piling into the ground.
[0011] Two types of diesel hammer with different modes of fuel
injection into the working compartment are known in the case of
diesel pile hammers of this kind.
[0012] In the case of a first mode of injection--high-pressure
injection--the fuel is injected, usually in the form of a finely
atomised fuel mist, at high pressure into the working compartment
of the cylinder during compression of air by the dropping piston.
This mist, together with the air, forms an ignitable mixture. In
the case of high-pressure injection the fuel ignites as early as
during the compression process and as soon as the compressed air
reaches a temperature which is sufficient to ignite the fuel
mixture.
[0013] The explosive combustion causes a high pressure to build in
the working compartment, via which on the one hand the piston is
decelerated and on the other hand this combustion pressure acts on
the impact piece which exerts a force on the piling, whereby the
piling is driven into the ground.
[0014] The compression process ends, at the latest, when the piston
strikes the impact piece, wherein the piston, which has already
been decelerated by the expanding combustion products before the
impact piece is struck, does not strike the impact piece with all
of its kinetic energy. Occasionally, in particular in the case of a
hard subsoil, the situation may even occur where the piston does
not touch the impact piece at all and, without prior contact with
the impact piece, is thrown upwards again by the combustion gases.
Under conditions of this kind the impact piece acts on the piling
only by way of the combustion gas cushion.
[0015] Diesel pile hammers in which a high-pressure injection is
used are therefore less suitable for driving home heavy piling or
in the case of difficult ground conditions with hard layers.
[0016] In addition, a diesel pile hammer of this kind becomes very
hot during operation and the system of high-pressure injection has
a tendency to misfire in the event of over-heating. A system of
this kind is moreover susceptible to repair and has a relatively
complicated construction. This brings with it the drawback that a
diesel pile hammer with high-pressure injection can be only poorly
repaired, or not repaired at all, in situ on building sites.
[0017] Advantages of high-pressure injection lie in good,
relatively residue-free combustion and good starting behaviour of
the diesel pile hammer as well as a good is pile-driving effect
with soft ground layers.
[0018] The second type of mode of injection is what is known as
impact atomisation, which, in contrast to high-pressure injection,
can also be called low-pressure injection.
[0019] In this case the fuel is introduced, usually in the form of
a fuel jet, at low pressure into the working compartment at the
start of the compression process and thereafter first of all rests
as an area of fuel on the upper end face of the impact piece.
[0020] The air in the working compartment is compressed by the
dropping piston until the piston strikes the impact piece. At this
instant the liquid fuel is atomised by the striking piston face and
fin this state ignites in the hot, compressed air. The piston is
then thrown upwards by the explosion, whereupon a further working
cycle can begin.
[0021] Until it strikes the impact piece the piston's descent is
decelerated only by the air that is situated in the working
compartment and which it compresses. This means the kinetic energy
of the piston is largely transferred to the impact piece, whereby,
with the same piston weight, much higher impact forces can be
exerted on the piling than is the case with the above-described
high-pressure injection. The impact of the piston on the impact
piece takes place before combustion of the fuel.
[0022] Diesel pile hammers which use low-pressure injection are
less suitable for use with low ground resistances. In these cases
the compression is reduced owing to the lower resistance of the
ground, since the decreasing compressive pressure is already
transferred to the piling via the downward-moving impact piece. The
working compartment is factually enlarged thereby, and this, in
turn, is at the expense of the compressive pressure.
[0023] Combustion is thus of only reduced quality in the case of
soft ground, and this can lead to undesirable residues (carbon
block, unburned fuel in the combustion gases) which burden the
environment.
[0024] One advantage of impact atomisation is that the kinetic
energy of the piston is effectively used since the piston strikes
the impact piece with force. In addition a diesel pile hammer with
impact atomisation has less of a tendency to overheat, is less
susceptible to faults and is easier to control than a diesel pile
hammer with high-pressure injection.
[0025] Previously the drawback that a diesel pile hammer operating
according to one of the two operating principles could only ever
take account of specific local circumstances had to be accepted in
the case of diesel pile hammers. If in situ it turned out that the
quality of the ground was or would be different than planned,
either work had to be continued using the apparatus that was not
optimal or a different diesel pile hammer had to be acquired, and
this led to lost time and higher costs.
[0026] The aim of the invention is to create a diesel pile hammer
which can be used in different ground conditions with good impact
effectiveness and good quality of combustion at the same time.
[0027] This object is achieved with a diesel pile hammer of the
type discussed in the introduction in that: [0028] (f) the fuel
supply device is constructed in such a way that the fuel is
injected into the working compartment in a first mode of injection
as an atomised fuel mist and in a second mode of injection as a
fuel jet.
[0029] This makes it possible for the diesel pile hammer to operate
in soft ground conditions with high-pressure injection but in the
case of hard ground layers may be operated using the
above-discussed impact atomisation.
[0030] Adjustment of the effectiveness of the diesel pile hammer,
with simultaneous optimisation of combustion, which also partially
depends on the ground resistance, to soft or hard ground layers is
thus ensured.
[0031] It is advantageous if the fuel mist of the first mode is of
injection flows into the working compartment in the vicinity of the
upper end face of the impact piece substantially vertically to the
direction of movement of the piston. This achieves good
distribution of the fuel mist in the working compartment, and this
leads to good and effective combustion of the resulting fuel/air
mixture overall.
[0032] The fuel jet of the second mode of injection is
advantageously injected into the working compartment of the
cylinder in such a way that it obliquely strikes the piston-side
end face of the impact piece. This ensures that the liquid fuel is
well distributed over the end face, and this leads to improved
atomisation when the piston strikes the impact piece, and therewith
to good and effective combustion.
[0033] A diesel pile hammer that is easy to implement in terms of
construction is produced by the embodiment in which the fuel supply
device comprises at least one high-pressure injection nozzle and at
least one low-pressure injection nozzle, to which via one pipe in
each case and by way of at least one fuel pump, of which the inlet
communicates with a fuel tank, a specific amount of fuel can be
supplied with every working cycle of the diesel pile hammer.
[0034] Already known components of a high-pressure injection or a
low-pressure injection can thus advantageously be used to achieve a
diesel pile hammer according to the invention.
[0035] It is advantageous if the amount of fuel supplied via a
high-pressure injection device in each case and the amount of fuel
supplied via a low-pressure injection device in each case is
adjustable, preferably via the fuel pump itself. The impact
intensity of the diesel pile hammer can be adapted to different
ground conditions as a result, depending on the hardness of the
subsoil.
[0036] Alternatively use of controllable regulators or valves that
can be controlled in terms of their opening time is also
possible.
[0037] An injection of fuel that functions well and is reliably
adapted to a working cycle of the diesel pile hammer in terms of
time is achieved if the dropping piston controls or actuates the
fuel pump or an injection valve.
[0038] Clogging of the usually very fine injection nozzles of the
high-pressure injection device is easily prevented if the fuel pump
of the high-pressure injection device supplies a minimum amount of
fuel with every working cycle. Fuel consequently flows through the
injection nozzle with every cycle and the nozzle is thus liberated
or kept free of impurities.
[0039] A combustion chamber that ensures effective combustion is
given if the end face of the piston delimiting the working
compartment of the cylinder is stepped by a circumferential
radially external step. The combustion chambers which is formed if
the end face of the piston rests on the inner end face of the
impact piece, is thus toroidal and has a relatively low volume.
[0040] According to a further development of the invention it is
provided that in a third mode of injection the fuel is injected
into the working compartment of the cylinder as both an atomised
fuel mist and as a fuel jet.
[0041] A transition between the first and second mode of injection
can thus be achieved.
[0042] Embodiments of the invention will be described in more
detail hereinafter with reference to the drawings, in which:
[0043] FIG. 1 shows partially in section, a lower portion of a
diesel pile hammer that faces the subsoil,
[0044] FIGS. 2 and 3 show a low-pressure injection device with fuel
pump, of which the actuating ram is shown in different starting
positions, and
[0045] FIG. 4 schematically shows an electronic controller of the
amount of fuel which is supplied to the working compartment.
[0046] FIG. 1 shows a diesel pile hammer 10 with a cylinder 12,
open on both sides, which in practice can have a length of 5 to 10
m and a diameter of 0.5 to 1 m.
[0047] A piston 14 runs in the cylinder 12. An impact piece 16 that
is coaxial thereto slidably engages in the open, lower end of the
cylinder 12. The lower end of the cylinder 12 carries an annular
bearing unit 20 that is secured by means of screws, of which one is
identified by reference numeral 18 in the figure. A central shaft
portion 22 of the impact piece 16 is tightly and slidably guided in
this bearing unit and has an external diameter which is reduced
compared with the internal diameter of the cylinder 12.
[0048] Formed on the lower end of the shaft portion 22 is an impact
plate 24, located below the cylinder, of which the outer, lower,
convex delimiting face 26 cooperates during operation with the
upper end of a piling that is to be driven home, such as a concrete
pile, an iron girder, a sheet piling element or the like.
[0049] Formed on the upper end of the shaft portion 22 of the
impact piece 16 is a piston portion 28 with a plurality of
circumferential, axially spaced-apart sealing rings 30 which run on
the inner circumferential surface 32 of the cylinder 12. The upper
side of the piston portion 28, together with the lower side of the
piston 14 and the circumferential wall of the cylinder 12, delimits
a working compartment 34. The end face 36 of the impact piece 16
that faces the working compartment 34 of the cylinder 12 is surface
ground with a flat fuel depression 37.
[0050] A damping ring 38 is arranged between the impact plate 24 of
the impact piece 16 and the bearing unit 20 of the cylinder 12. A
further damping ring 40 is effective in the vicinity of the bearing
unit 20 between the upper side of the bearing unit 20 and the lower
side of the piston portion 28 of the impact piece 16.
[0051] A lower working end 44 of the piston 14, which is provided
with circumferential, axially spaced-apart sealing rings 42, runs
inside the cylinder 12 above the impact piece 16.
[0052] The lower, free, flat surface ground end face 46 of the
piston 14 is stepped by a radially external, circumferential step
48, forming a toroidal-shaped combustion chamber if the end face 46
of the piston 14 rests on the end face 36 of the impact piece
16.
[0053] The working end 44 of the piston 14 is formed on a mass
portion 50 thereof which extends into the upper portion (not shown
here) of the cylinder 12.
[0054] To raise the piston 12 to start the diesel pile hammer for
the first time the mass portion 50 has a driving shoulder (not
shown here) on which a releasable hook of a lifting device (not
shown here either) can act.
[0055] A high-pressure injection device 52 with a schematically
indicated fuel pump 53 and a high-pressure injection nozzle 54 is
arranged on the circumferential wall of the cylinder 12. In the
upper end position, shown in the figure, of the impact piece 16 the
injection nozzle 54 of the high-pressure injection device 52 opens
into the working compartment 34 of the cylinder 12 just above the
end face 36 of the impact piece 16 if, in other words, an upper
annular face 56 of the impact plate 24 of the impact piece 16 rests
against the damping ring 38.
[0056] In addition to the high-pressure injection nozzle 54 further
high-pressure injection nozzles may be arranged (preferably at the
same level) so as to be distributed in the circumferential wall of
the cylinder 12.
[0057] The high-pressure injection nozzle 54 is connected to the
outlet of the fuel pump 53 arranged on the outside of the cylinder
12 via a pipe 58, the inlet of the fuel pump communicating with a
fuel tank 55 filled with diesel oil. The fuel pump 53 is actuated
via an actuating ram 57 if the piston 14 drops downward.
[0058] The high-pressure injection device 52, in particular the
injection nozzle 54 thereof, is constructed in such a way that it
injects the diesel oil supplied to it at high pressure into the
working compartment 34 of the cylinder 12 substantially as finely
atomised mist 76. The injection nozzle 54 is in the process
oriented in such a way that the diesel oil is injected
substantially vertically to the movement direction of the piston
14.
[0059] A further fuel pump 60, which is driven by an actuating ram
61 that is pre-tensioned into the interior of the cylinder 12 when
the piston 14 drops, is connected at the delivery side by a pipe 64
to a low-pressure injection nozzle 66 and forms therewith a
low-pressure injection device 68. The fuel pump 60 communicates
with a fuel tank 62 filled with diesel oil. The low-pressure
injection device 68 is provided on and in the circumferential wall
of the cylinder 12 so as to be axially spaced apart from the
high-pressure injection device 52 in the direction of the upper end
of the cylinder 12. Its injection nozzle 66 is constructed and
oriented in such a way that the delivered fuel is injected in a
substantially continuous jet approximately centrally onto the end
face 36 of the impact piece 16.
[0060] Supplementary, further low-pressure injection nozzles,
preferably located at the same height as the low-pressure injection
nozzle 66, may also be distributed over the circumference of the
cylinder 12 in this case as well.
[0061] Overall the high-pressure injection device 52, the
low-pressure injection device 68 and the fuel tanks 55 and 62
therefore together form a fuel supply device.
[0062] The fuel pumps 53 and 60 can be adjusted independently of
each other in terms of their delivery, so the fuels supplied to the
high-pressure injection nozzle 54 and the low-pressure injection
nozzle 66 is continuously variable, as will be described
hereinafter.
[0063] Above the low-pressure injection device 68 the
circumferential wall of the cylinder 12 is penetrated by obliquely
upwardly extending working connecting pieces 70 and 72, as may be
seen from the figure. Combustion air is drawn in and combustion
gases are released via these connecting pieces.
[0064] Finally the diesel pile hammer 10 comprises lubricant pumps
(not shown separately here) and lubricant nozzles distributed in
the circumferential direction of the cylinder 12, via which
lubricant is delivered between the piston 14 and the inner
circumferential surface 32 of the cylinder 12.
[0065] FIGS. 2 and 3 show the fuel pump 60 of the low-pressure
injection device 68, wherein its actuating ram 61 is shown in two
different starting positions.
[0066] The actuating ram 61 extends through the circumferential
wall of the cylinder 12. It ends at the outside in a pump ram 80
and inside the cylinder 12 in a wedge-shaped actuating portion 82
running in an appropriate recess 81 in the circumferential wall of
the cylinder 12, the ram and actuating portion being connected to
each other by a piston rod 84. A concave actuating face 86 of the
actuating portion 82 that points toward the interior of the
cylinder 12 has a curvature which matches that of the inner
circumferential surface 32 of the cylinder 12 and is upwardly and
radially outwardly inclined.
[0067] Depending on the starting position of the actuating ram 61,
the actuating surface 86 thereof projects completely, as may be
seen in FIG. 2, or with a lower region, and this may be seen in
FIG. 3, into the interior of the cylinder 12.
[0068] Approximately centrally between the pump ram 80 and the
actuating portion 82 an upwardly pointing stop plate 88 is
connected to the piston rod 84 and cooperates with a radially
adjustable stop plate 90, secured to the housing, of a
stroke-adjusting device 92. The stop plate 90 runs across a
threaded hole 94 on a radially outwardly extending threaded spindle
96, which can be rotated by a servomotor 98 which is only
schematically indicated in the drawings.
[0069] The pump ram 80 runs in a pump cylinder 100, arranged on the
outside of the circumferential wall of the cylinder 12, the pump
cylinder comprising a fuel outlet 102, which communicates with the
injection nozzle 66, and a fuel outlet 104, which is fluidically
connected to the fuel tank 62.
[0070] The actuating ram 61 is pressed by a spring 106 always in
the direction of the interior of the cylinder 12, so in the
starting position the stop plate 88 rests against the stop plate 90
of the stroke adjusting device 92.
[0071] FIG. 2 shows the position of the stop plate 90 in which the
pump piston 80 has its greatest stroke. This means that in this
position of the stop plate 90 the amount of fuel delivered per
stroke by the fuel pump 60 is the maximum.
[0072] If accordingly, starting from the position shown in FIG. 2,
the threaded spindle 96 rotates the adjusting device 92, the sop
plate 90 is moved radially outwards. The stroke of the pump ram 80
in the pump cylinder 100 is reduced thereby, and therewith the
volume of the working compartment 108 of the fuel pump, and this
thus leads to a reduction in the amount of fuel which can be
delivered per stroke. FIG. 3 shows such a position of the stroke
adjusting device 92.
[0073] The high-pressure injection device 52 can be constructed so
as to correspond with the above-described embodiment of the
low-pressure injection device 68. Components of the high-pressure
injection device 52 are provided with corresponding reference
numerals in FIGS. 2 and 3.
[0074] The amount of fuel delivered into the working compartment 32
of the cylinder 12 by the high-pressure injection device 52 or by
the low-pressure injection device 68 can consequently be
predetermined by the respective position of the associated stop
plate 90 secured to the housing.
[0075] FIG. 4 shows an electronic controller for the amount of fuel
supplied to the working compartment 32 of the cylinder 12, wherein
components corresponding to those in FIGS. 1 to 3 are identified by
the same reference numerals.
[0076] The high pressure injection nozzle 54 and the low-pressure
injection nozzle 66 are each fluidically connected to a
spring-loaded solenoid valve 110. The valves communicate with one
pressurised fuel accumulator 112 respectively which is fed by the
corresponding fuel pumps 53 and 60 via non-return valves 113.
[0077] The amount of fuel which is to be supplied to the
high-pressure injection nozzle 54 and the low-pressure injection
nozzle 66 is input into a computer 114 with a display monitor 116
via a keypad 118. Information about the present ground conditions
is also possible as input parameters, with the aid of which data
adapted by appropriate software is then calculated for the
high-pressure injection device 52 and the low-pressure injection
device 68.
[0078] From the input data the computer 114 calculates the period
over which the solenoid valves 110 are open, whereby a specific
amount of fuel is injected through the high-pressure injection
nozzle 54 or through the low-pressure injection nozzle 66 into the
working compartment 32 of the cylinder 12 according to the opening
time of the valves.
[0079] The opening times determined by the computer are transmitted
to a control unit 120 which forwards these as control signals to a
controllable monostable 122 of the high-pressure injection device
52 or the low-pressure injection device 68 respectively.
[0080] At the input-side the monostables 122 are connected via
contact terminals 124 to actuating rams 126 that project into the
path of the piston shown only schematically in FIG. 4 and are
activated by a movement of the actuating ram 126. Alternatively
sensors that operate contactlessly can be used which respond if the
piston 14 reaches a predefined position on dropping.
[0081] At the output side the monostables 122 are each connected to
an amplifier 128 which guides the amplified signal of the
monostable 122 to the corresponding solenoid valve 110, whereupon
the valve adopts its open position corresponding to the
respectively adjusted pulse width of the monostable 122. If the
switching time of the two monostables 110, which can be selected so
as to be different for the high-pressure injection device 52 and
the low-pressure injection device 68, is attained the solenoid
valves 110 are transferred into their closed position again by
spring force.
[0082] A solenoid valve 110, a fuel reservoir 112 and a monostable
122 combined thus form a fuel source of which the delivery can be
controlled.
[0083] The above-described diesel pile hammer 10 works as
follows:
[0084] In the starting state the piston 12 is raised by the holding
device, already discussed but not shown, into an upper position.
After release it drops downwards from the raised position under the
effect of gravity, closes the working connecting pieces 70 and 72
and with its end face 46 actuates the actuating ram 57, 61 of the
high-pressure injection device 52 or the low-pressure injection
device 68.
[0085] If the embodiment of the injection devices 52 and 68 shown
in FIGS. 2 and 3 is used, this means that the piston 14 strikes the
actuating face 86 of the actuating portion 82 of the actuating ram
61 from above. As the piston 14 continues to drop the ram is
displaced, to the left in FIGS. 2 and 3. The pump ram 80 is
displaced in the direction of the outlet 102 of the pump cylinder
100 as a result, whereby the fuel in the working compartment 108 is
conveyed to the injection nozzle 54 or 66 and injected into the
working compartment 34 of the cylinder.
[0086] An ignitable mixture of fuel droplets and air forms in the
working compartment 34, be it as a result of the high-pressure
injection or impact atomisation. The injection nozzles 56 and 66
will accordingly inject a specific amount of diesel oil into the
working compartment 34 of the cylinder 12 in the above-described
manner respectively, individually or in combination, depending on
the setting of the fuel pumps 53 and 60. If one of the injection
devices 52, 68 should not inject fuel into the working compartment
34 of the cylinder 12, by controlling the servomotor 98 its
actuating ram 57 or 61 is radially outwardly displaced until the
respective actuating portion 86 no longer projects into the
interior of the cylinder 12.
[0087] When using an electronic controller, which is shown in FIG.
4, the desired parameters are programmed via the computer 114. If
one of the two injection devices 52, 68 should not inject fuel into
the working compartment 34 of the cylinder 12, the corresponding
monostable 122 is controlled to pulse width zero in this case, so
the corresponding solenoid valve 110 is not opened when the piston
14 drops.
[0088] When the piston 14 strikes the impact piece 16 and/or across
the gas cushion between piston and impact piece, a downwardly
directed force is exerted on the impact piece, and via the impact
piece on the piling, which drives the piling further into the
ground.
[0089] During the subsequent upwards movement of the piston 14,
triggered by the explosive combustion of the diesel oil, the piston
releases the working connecting pieces 70, 72, whereby the
combustion gases expand and flow off via the working connecting
pieces 70, 72. The piston 14 is accordingly thrown further upwards
while drawing in fresh combustion air, and this likewise takes
place via the working connecting pieces 70, 72, until it reaches
its upper end position and repeats the described working cycle.
[0090] The diesel pile hammer can therefore optionally be operated
only by means of the high-pressure injection device 52 in a first
mode of injection as atomised fuel mist, only by means of the
low-pressure injection device 68 in a second mode of injection as a
fuel jet or by a combination of these two in a third mode of
injection as both atomised fuel mist and fuel jet. It may be
adjusted to different ground conditions thereby.
[0091] Soft ground conditions, i.e. low ground resistance, usually
occur at the start of a driving-home operation, whereby it is
advantageous to operate the diesel pile hammer 10 only or
predominantly with high-pressure injection 52 at this time. The
low-pressure injection device 68 can optionally also be supplied
with a small amount of fuel, so the impact atomisation already
mentioned is also used by way of assistance.
[0092] If the piling reaches more load-bearing and therewith
usually harder layers of the ground, the proportion of low-pressure
injection can he increased by appropriate modification of the
allocated amount of fuel via the low-pressure injection device 68,
whereby the direct force transmission of the piston 14 to the
impact piece 16 and therewith to the piling is increased, as has
already been described.
[0093] If the ground conditions at greater depths change to softer
layers again, such as sand layers, the ratio of the amounts of fuel
supplied by the injection devices 52 and 68 can be adapted
accordingly. Individual adjustment of the function and mode of
operation of the diesel pile hammer 10 to different ground
conditions that change per se is thus possible, wherein good and
complete combustion of the diesel oil is ensured.
[0094] When working in hard ground layers in which the principle of
impact atomisation is used, the high-pressure injection device 52
is preferably operated with a small amount of fuel with every
working cycle. The fuel pump 53 of the high-pressure device 52
therefore supplies the high-pressure injection nozzle 54 with a
minimum amount of fuel with every working cycle. This prevents the
inject-ion nozzle 54, as a rule constructed so as to be very fine,
of the high-pressure injection device 52 from clogging as a result
of combustion residues or other impurities, such as lubricant
residues, and no longer functioning.
[0095] In a modification it is possible to use only a single pump
to provide pressurised fuel, which pump is used in equal measure
for the high-pressure injection and the low-pressure injection
(optionally via a pressure reducer or a regulator).
[0096] And in a further modification a fuel amount controller may
be dispensed with during operation if a particularly simply
constructed diesel ram is desired and/or the changes in load are
small.
* * * * *