EP2871286B1 - Pile driver - Google Patents

Description

The invention relates to a hammer, comprising a cylinder, a displaceably guided in the cylinder piston and slidably guided in the cylinder hammer head according to the preamble of claim 1. The invention further relates to a method for operating a pile driver according to claim. 9

Ramming hammers, which are regularly operated in the prior art with diesel, which is why they are also referred to as diesel rams, diesel hammers or diesel bears, especially for foundation work of the construction industry for driving piles of all kinds, such as concrete pillars, iron supports, sheet piling or the like in a building ground Commitment.

To start such a diesel ram, the piston is pulled upwards by means of a notching device inside the cylinder and disengaged at a certain height, whereby it falls down on the striking piece under the action of gravity. When falling down, a fuel pump is actuated by the piston, via which one or more injection nozzles supply fuel, in particular diesel oil. By the falling piston, the air in the combustion chamber of the cylinder is compressed and thereby heated so that ignited in the combustion chamber fuel / air mixture, whereupon it burns explosively. As a result of the explosion energy released in this process, the piston is hurled upward again for a new working cycle; at the same time the pile is driven over the hammer in the ground.

In such diesel hammers, two types with different types for injecting diesel oil into the combustion chamber are known. In the so-called high-pressure injection of the fuel during the compression of the air by the falling piston at high pressure in the form of a finely atomized fuel spray in the Combustion chamber of the cylinder injected. This mist together with the air forms an ignitable mixture. The fuel ignites in the high pressure injection already during the compression process, as soon as the compressed air reaches a temperature sufficient to ignite the fuel mixture. Due to the explosive combustion, a high pressure builds up in the combustion chamber, by which on the one hand the piston is braked. On the other hand, this combustion pressure acts on the hammer, which exerts a force on the pile, whereby this is driven into the ground.

The compression process ends at the latest with the impact of the piston on the hammer, the piston, which was already braked before striking the hammer by the expanding combustion products, does not strike with full kinetic energy to the hammer. At times, especially in a hard ground, even the case may occur that the piston does not touch the hammer at all and is thrown back up without prior contact with the hammer by the combustion gases. Under such conditions, the impact piece acts only on the combustion gas cushion on the Rammgut. Therefore, diesel hammers using high pressure injection are less suitable for ramming heavy pile or difficult ground conditions with hard layers.

In addition, such a diesel hammer in operation is very hot and the system of high-pressure injection tends to misfire when overheated. Such a system is also prone to repair and has a relatively complicated structure. This has the disadvantage that a diesel hammer with high-pressure injection on site on site is poor or impossible to repair.

Advantages of the high-pressure injection are the good, relatively residue-free combustion, a good starting behavior of the diesel hammer and a good pile action on soft soil layers.

In the so-called impact atomization, which is also referred to as low-pressure injection in contrast to the high-pressure injection, the fuel at the beginning of the compression process at a lower pressure in the form of a fuel jet introduced into the combustion chamber and is then first as a fuel surface on the upper face of the hammer. The air in the combustion chamber is compressed by the falling piston until it strikes the hammer. At this moment, the liquid fuel is atomized by the impinging piston surface and ignites in this state in the hot compressed air. The piston is then thrown upwards by the explosion, whereupon another cycle of work can begin.

Until it hits the striking piece, the piston is only braked in its case by the air in the combustion chamber and compressed by it. This means that the kinetic energy of the piston is transferred to a large extent to the striking piece, whereby at the same weight of the piston significantly higher impact forces can be exerted on the pile material than is the case with the high-pressure injection. The impact of the piston on the hammer occurs in time before the combustion of the fuel.

Diesel hammers that use low pressure fuel injection are less well suited for use with low ground drag. In these cases, the compression is reduced due to the lower resistance of the soil, because even the building up compression pressure is transmitted via the downwardly moving hammer on the Rammgut. The combustion chamber is actually enlarged, which in turn is at the expense of the compression pressure. Combustion therefore only proceeds with reduced quality in soft soils, which can lead to undesirable residues (soot, unburned fuel in the combustion gases) which pollute the environment.

An advantage of the impact atomization is that the kinetic energy of the piston is used effectively, since the piston strikes hard on the hammer. In addition, a diesel hammer with impact atomization is less likely to overheat, is less prone to failure, and easier to operate than a high-pressure injection diesel hammer.

So far, had to be taken with diesel hammers the disadvantage in purchasing that working on one of the two working principles diesel hammer only ever certain local circumstances. It turned out on-site that the ground condition was different or was planned as before, had to be worked on either with the not optimal device or another Diesel hammer to be procured, which led to time loss and higher costs.

In the WO 2006/072297 A1 is a diesel hammer described in which the diesel oil can be injected either as atomized fuel mist (high-pressure injection) and / or as a fuel jet (low-pressure injection) in the combustion chamber. This diesel hammer has proven itself in practice. In this diesel hammer it is possible to operate it in soft ground conditions with high-pressure injection, but in hard soil layers with low-pressure injection or impact atomization. Thus, an adjustment of the efficiency of the diesel hammer while optimizing the combustion, which also depends in part on the soil resistance, soft or hard layers of the soil is guaranteed.

However, it has been shown in practice that incomplete fuel burns can occur in the different operating modes, as a result of which combustion residues remain in the combustion chamber.

The invention aims to remedy this situation. The invention is based on the object to improve a pile hammer of the aforementioned type with the same function and reliability of the fuel combustion process and to avoid the formation of combustion residues. According to the invention, this object is achieved by a pile hammer with the features of the characterizing part of patent claim 1.

With the invention, a pile hammer of the aforementioned type is created in which improves the function and reliability of the fuel combustion process and the formation of combustion residues is avoided. Characterized in that a Primärzufülzuführeinrichtung is arranged, comprising a connected to a high-resistance fuel having a primary fuel tank, designed as a high-pressure injector primary fuel nozzle and a Zündölzuführeinrichtung is arranged, which comprises a connected to an ignition oil having Zündöltank connected, designed as a low-pressure injector Zündöldüse, a well-defined combustion process can be achieved. Through the use of a primary fuel with high anti-knocking properties, a homogeneous distribution of the fuel-air mixture is effected, whereby an improvement of the combustion is achieved. In this case, the primary fuel can be introduced at the beginning of the compression stroke, whereby more time is available for the mixture formation and evaporation of the primary fuel. The ignition of the primary fuel takes place by autoignition of the ignition oil, the ignition of which takes place exactly at the time of impact of the piston on the hammer, so always at the optimum time.

Since only a minimum amount of ignition oil for spark ignition of the primary fuel-air mixture is required at each cycle, a very clean and particulate combustion process is particularly effected. As a primary fuel, any suitable fuel with high anti-knocking properties, in particular ethanol, natural gas, LPG, biogas, premium gasoline or E85 can be used. The ignition oil may be any suitable fuel which is self-igniting by means of the combustion air heated by compression, such as diesel oil, heating oil, biodiesel or kerosene.

In a further development of the invention, the Zündöldüse is designed such that the ignition oil can be applied in the form of a jet on the hammer. As a result, a puddle formation is achieved on the hammer, whereby a premature self-ignition is counteracted. In this case, the primary fuel nozzle is preferably designed such that the primary fuel in the form of an atomized fuel spray can be introduced into the combustion chamber. The design of the primary fuel and Zündöldüsen must be matched to the primary fuel used.

In an embodiment of the invention, the primary fuel nozzle is arranged such that the fuel mist is orthogonal to the direction of movement of the piston in the vicinity of the end face in the combustion chamber can be introduced. As a result, a homogeneous distribution of the primary fuel-air mixture is achieved.

In a further embodiment of the invention, the primary fuel nozzle and the Zündöldüse are arranged at different vertical distances from the hammer. In this case, the Zündöldüse is preferably arranged above the primary fuel nozzle seen from the hammer piece ago. In this way, initially the jet-shaped introduction of a Zündölpfütze done on the hammer, after which takes place with increasing compression of the air, the injection of the primary fuel. As a result, premature self-ignition of the ignition oil is counteracted further.

In a further development of the invention, the primary fuel nozzle and the Zündöldüse are each connected to a pump device which are controllable by the falling piston, wherein preferably at least one of the pump means comprises a pump plunger which protrudes into the cylinder and is designed such that it by sweeping the piston when falling a pump device operated by the injection process is initiated. As a result, a mechanical, very robust and störunanfällige control of the fuel injection process is achieved.

The invention is further based on the object to provide a method for operating a piling hammer of the aforementioned type, which allows an improvement of the fuel combustion process while avoiding the formation of combustion residues with the same function and reliability of the hammer. According to the invention, this object is achieved by a method having the features of the characterizing part of patent claim 9.

With the invention, a method for operating a pile hammer of the aforementioned type is provided, which allows an improvement of the fuel combustion process while avoiding the formation of combustion residues with the same function and reliability of the hammer. Characterized in that the ignition of the primary fuel-air mixture takes place only when the piston by the spontaneous ignition of the ignition oil, a good homogenization of the primary fuel-air mixture is effected, whereby an optimal combustion is promoted. In this case, primary fuel and ignition oil are preferably introduced into the combustion chamber at different times.

Particularly preferably, first a small amount of ignition oil is sprayed onto the striking piece, whereby a Zündölpfütze is formed, after which the primary fuel is introduced in the form of an atomized fuel spray into the combustion chamber, before the located on the hammer piece Zündöl atomized by the impact of the piston on the hammer and is ignited.

Other developments and refinements of the invention are specified in the remaining subclaims. An embodiment of the invention is illustrated in the drawing and will be described in detail below. The only FIG. 1 shows the schematic representation of a piling hammer.

The hammer chosen as an exemplary embodiment comprises a cylinder 1 which is open on both sides and which can regularly have a length of 3 to 8 meters and a diameter of 0.2 to 1.5 meters. In the cylinder 1, a piston 2 is slidably disposed. A coaxial to this impact piece 3 engages slidably in the open lower end of the cylinder 1 a. At the lower end of the cylinder 1, an annular bearing unit 9 is fixed, in which a middle shaft portion 31 of the hammering piece 3 is guided tightly and displaceably, which has a relation to the inner diameter of the cylinder 1 reduced outer diameter. The pile hammer is mounted on the cylinder 1 arranged guide jaws 13 along a Mäklers 8 vertically.

At the lower end of the shank portion 31 there is formed a striking plate 32 located below the cylinder 1, the outwardly directed lower convex boundary surface 33 cooperating in operation with the upper end of a driven-in pile material to be driven in.

At the upper end of the shaft portion 31 of the striking piece 3, a piston portion 34 is formed with a plurality of circumferential, axially spaced sealing rings which run on the inner circumferential surface 11 of the cylinder 1. Through the top of the piston portion 34 of the hammer 3, a combustion chamber 12 is limited together with the underside of the piston 2 and the inner circumferential surface 11 of the cylinder 1.

The combustion chamber 12 of the cylinder 1 facing end face of the hammer 3 is ground flat with a shallow fuel well.

Between the impact plate 32 of the hammer 3 and the bearing unit 9 of the cylinder 1, a damping ring 91 is arranged. A further damping ring 92 is arranged adjacent to the bearing unit 9 between the upper side of the bearing unit 9 and the underside of the piston portion 34 of the hammer 3.

Above the hammer 3 runs in the interior of the cylinder 1 with a circumferential, axially spaced sealing rings 93 versehenes, lower working end 23 of the piston 2. The lower free, ground flat end face 21 of the piston 2 is discontinued by a radially outboard circumferential stage.

At the lower working end 23 of the piston 2, a mass portion 22 is formed, which extends in the upper portion of the cylinder 1 inside. On the peripheral wall of the cylinder 1 there is arranged a primary fuel supply 4 comprising a primary fuel pump 41 which is connected via a conduit to a primary fuel nozzle 42 in the form of a high pressure injector. The primary fuel pump 41 is fed via a primary fuel tank 45 with a high anti-knock fuel, in this case ethanol. Instead of ethanol, for example, natural gas, LPG, biogas premium gasoline or E85 (gasoline-ethanol mixture with 85 percent ethanol content) can be used.

The primary fuel pump 41, which is connected to the primary fuel tank 45 via a line, has a prestressed pump lever 44 projecting into the interior of the cylinder 1, via which it is driven when the falling piston 2 passes. The primary fuel supply device 4, in particular its primary fuel nozzle 42, is designed and aligned such that the discharged primary fuel is injected into the combustion chamber 12 essentially as a finely atomized mist.

Furthermore, an ignition oil pump 51, which is driven by a biased into the interior of the cylinder 1 pump lever 54 upon falling of the piston 2, conveyor side connected via a line with a formed as a low-pressure injection nozzle Zündöldüse 52 and forms with this an Zündölzuführeinrichtung 5. The Zündölpumpe 51 communicates with a filled with Zündöl used as diesel oil Zündöltank. The Zündölzuführeinrichtung 5 is axially spaced from the Primärzufstoffzuführeinrichtung 4 towards the upper end of the cylinder 1 and arranged in the peripheral wall of the cylinder 1. Your Zündöldüse 52 is formed and aligned such that the discharged ignition oil is injected in the form of a substantially continuous jet 53 approximately centrally on the end face of the hammer 3.

The design of the primary fuel and Zündölpumpen 41, 51 respectively arranged, projecting into the cylinder 1 pump lever 44, 54 correspond in the embodiment substantially the execution of the known in the art in the WO 2006/072297 described fuel pumps of the low pressure injector. Therefore, reference is made to the statements of this document with respect to these pumps at this point.

Furthermore, a lubricant pump 7 is arranged on the cylinder 1, which is connected to distributed in the circumferential direction of the cylinder 1 lubricant nozzles. Through the lubricant nozzles lubricant between the piston 2 and the inner circumferential surface 11 of the cylinder 1 is given.

The pile hammer described above operates as follows: In the initial state, the piston 2 is raised via the - not shown - release device in an upper position. After notching it falls from there under the action of gravity down, closes the working socket 16 and actuates with its end face 21 successively the pump lever 54, 44 of the Zündölzuführeinrichtung 5 and the Primärzufülzuführeinrichtung 4. This is initially a jet-shaped application of a small amount of ignition oil on the Schlagstück 3, which forms a puddle there. Subsequently, the primary fuel, in this case ethanol, is atomized via the primary fuel nozzle 42 into the combustion chamber 12, which is thus mixed with air and compressed via the falling piston 2. Upon impact of the piston 2 on the hammer 3, the Zündölpfütze is atomized and self-ignited, whereby the ignition of the compressed primary fuel-air mixture 6 takes place.

With the opening of the piston 2 on the hammer 3 is a quasi-downward force exerted on the hammer 3 and this on the pile material, which drives the pile further into the ground. During the subsequent upward movement of the piston 2 triggered by the explosive combustion of the primary fuel, the latter releases the working nozzles 16, as a result of which the combustion gases relax and flow out via the working nozzles 16. The piston 2 is now thrown with the intake of fresh air through the working nozzle 16 further up until it has reached its upper end position and repeats the cycle described.

Claims (11)

1. Pile driver comprising a cylinder (1), a piston (2) movably guided in the cylinder (1), a striking piece (3) movably guided in the cylinder (1), which is arranged below the piston (2) in the operating position of the pile driver, a combustion chamber (12), which is axially delimited by a front face (30) of the striking piece (3) inside the cylinder (1) and a front face (21) of the piston (2) as well as a fuel supply device, by means of which a predetermined amount of fuel is introducible into the combustion chamber (12) during each work cycle, wherein a primary fuel supply device (4) is arranged comprising a primary fuel nozzle (42) designed as a high pressure injection nozzle connected to a primary fuel tank (45) containing a fuel with high anti-knock characteristics, characterised in that furthermore an ignition oil supply device (5) is arranged comprising an ignition oil nozzle (52) designed as a low pressure injection nozzle connected to an ignition oil tank containing ignition oil.
2. Pile driver according to claim 1, characterised in that the ignition oil nozzle (52) is designed in a way that the ignition oil can be applied to the striking piece (3) in the form of a jet.
3. Pile driver according to claim 1 or 2, characterised in that the primary fuel nozzle (42) is designed in a way that the primary fuel can be introduced into the combustion chamber (12) in the form of an atomised fuel spray.
4. Pile driver according to claim 3, characterised in that the primary fuel nozzle (42) is arranged in a way that the fuel spray can be introduced into the combustion chamber (12) orthogonally to the direction of movement of the piston (2) close to the front face (30) of the striking piece (3).
5. Pile driver according to one of the previous claims, characterised in that the primary fuel nozzle (42) and the ignition oil nozzle (52) are arranged in different vertical distances to the striking piece (3).
6. Pile driver according to claim 5, characterised in that the ignition oil nozzle (52) is arranged above the primary fuel nozzle (42) as viewed from the striking piece (3).
7. Pile driver according to one of the previous claims, characterised in that the primary fuel nozzle (42) and the ignition oil nozzle (52) are respectively connected to a pumping device (41, 51), which are controllable by the falling piston (2).
8. Pile driver according to claim 7, characterised in that at least one of the pumping devices (41, 51) has a pump lever (44, 54), which protrudes into the cylinder (1) and is designed in a way that it actuates a pumping device (41, 51) by passing over the falling piston (2), by means of which an injection process is initiated.
9. Method for operating a pile driver according to one of the previous claims, characterised in that during each work cycle a fuel pump is actuated by the falling of the piston (2), by means of which anti-knock primary fuel is introduced into the combustion chamber (12) via a primary fuel nozzle (42) designed as a high pressure injection nozzle, whereby in the combustion chamber (12) a primary fuel air mixture (6) is formed and an ignition oil pump (51) is actuated, by means of which a small amount of ignition oil is sprayed onto the striking piece (3) via an ignition oil nozzle (52) designed as a low pressure injection nozzle, whereafter the ignition oil is atomised and ignited when the piston (2) strikes the striking piece (3), whereby ignition of the primary fuel air mixture (6) takes place.
10. Method according to claim 9, characterised in that the primary fuel and the ignition oil are introduced into the combustion chamber (12) at different times.
11. Method according to claim 10, characterised in that first of all a small amount of ignition oil is sprayed onto the striking piece (3), whereby an ignition oil spill is formed, subsequently the primary fuel in the form of an atomised fuel spray is introduced into the combustion chamber (12) before the ignition oil on the striking piece (3) is atomised and ignited by the striking of the piston (2) onto the striking piece (3).

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