EP0228059B1 - Diesel hammer - Google Patents

Abstract

A diesel type pile-driver has a cup-shaped monkey (36) accommodated in a sliding fit on the external face of the lower end of the cylinder.

Description

The invention relates to a diesel ram according to the preamble of claim 1.

Such a diesel ram is described in DE-C-901 758. The cup-shaped impact piece represents an extension of the cylinder running surface with its inner surface, its outer surface is guided over a relatively small part of the axial extent through a guide surface which is formed on the inside of a cylinder end section with an enlarged diameter. To prevent rotation, the striking piece has guide fingers at the upper end which engage axially displaceably in corresponding guide grooves in the cylinder.

In this known diesel ram, the striker is not guided at the lower end, so that the guide surface located at the upper striker end must absorb larger tilting moments during operation.

In DE-A-27 53 806 a ram is also described, in which the end of the piston is pierced from the front and immersed in a cup-shaped, liquid-filled hammer. In this way, damping of the impact is achieved by throttling the fluid.

Another diesel ram is disclosed in DE-PS 20 40 924. The striking piece has a cylindrical shaft section which is guided in the sliding play in the lower end of the cylinder. The upper end face of the shaft section, together with the cylinder wall and the piston guided in the cylinder, limits the working area of the diesel ram.

If you want a good tilt-proof guidance of the striking piece, its shaft section must protrude far into the cylinder. For a given maximum axial dimension of the working space and a given axial dimension of the piston, the cylinder must therefore have a relatively large dimension. If one chooses the axial dimension of the shaft portion of the striker small with regard to compact axial dimensions of the ram, the striker can tilt under the unavoidable eccentric loads in rough use, with high forces acting on the inner surface of the cylinder. For this reason, a separate guide sleeve for the striker is used in practice in the lower cylinder end. This requires a high manufacturing effort.

The present invention is intended to further develop a diesel ram in accordance with the preamble of claim 1 in such a way that the tappet is guided with good tilt resistance and the overall ram dimensions are small.

This object is achieved according to the invention by a diesel ram according to claim 1.

In the diesel ram according to the invention, the impact piece is guided on the lower cylinder end using the outer surface of this cylinder end, which cooperates with a cylindrical peripheral wall of the cup-shaped impact piece. The guide device for the striking piece thus overlaps in the axial direction with the working area of the diesel ram, coaxially surrounding the latter. In this way, the overall axial dimension of the diesel ram is reduced by the axial dimension of the guide device for the striking element.

In the diesel ram according to the invention, the guide surfaces for the impact piece, which are fixed to the cylinder, lie on the outside of the cylinder. They are therefore particularly easily accessible for separate treatment with regard to high wear resistance, they can simply be specially hardened, armored, tempered (e.g. chrome-plated) and machined. Reconditioning after any wear and tear is also easy. The separate impact piece guide sleeve, which is necessary in the known diesel ram and whose inner surface must represent an exact continuation of the piston guide surface, can be omitted, which significantly reduces the manufacturing costs of the large, often many-ton cylinder. In the case of the diesel ram according to the invention, it is also necessary to machine internal guide surfaces (inside of the peripheral wall of the striking piece), but these lie on a ram part (striking piece) which is small and therefore easier to machine than the cylinder.

As already explained above, the diesel ram according to the invention can be built axially shorter with the same requirements for the hammer guide, which is advantageous with regard to use in confined spaces (ramming under a bridge or in a building with existing ceilings). Conversely, you can with the same axial Overall dimensions, as in the case of known diesel rams, increase the permissible stroke of the impact piece and improve the securing of the impact piece against tilting. Increasing the stroke of the striker is important for ramming on soft ground, where the piece to be driven in encounters little resistance at the beginning. In the case of known diesel rams with a small impact path, special precautionary measures must be taken to limit the impact force, sometimes a small ram has to be used.

Since the striker is cup-shaped in the diesel hammer according to the invention, no lubricant can leak from the cylinder. Lubricant running down the guide surfaces, for example, is collected on the bottom of the cup and atomized together with the fuel when it hits the piston and burned with it.

Another advantage of the diesel ram according to the invention is that the distance between the upper end face of the striking piece, on which the piston strikes, and the lower end face of the striking piece, which engages the pile to be driven in or the like or a striking cap placed thereon, is chosen to be much smaller can than with the known diesel ram. There, the entire volume of the shaft section of the impact piece guided in the lower cylinder end is used by the impact. Since, under the very large impact loads, springs such as steel, such as steel, can also be regarded as rigid in everyday life, harder impacts can thus be exerted on the workpiece to be driven in with the diesel hammer.

The circumferential wall of the cup-shaped impact piece, which is external to the diesel ram according to the invention, also represents an additional cooling surface for the impact piece, so that the latter heats up less during operation. If if desired, cooling fins can be provided in the diesel ram according to the invention to further improve the cooling of the striking element on its peripheral wall, as stated in claim 15.

Advantageous developments of the invention are specified in the subclaims.

The development of the invention according to claim 2 is advantageous in terms of a good seal of the working area of the diesel ram with low sliding friction between the hammer and cylinder.

In the case of a diesel hammer, the working space has no sections lying radially outside the cylinder wall, in which the gas flushing would be less effective.

With the development of the invention according to claim 5 with low sliding friction between the axially enlarged impact piece and the cylinder outer surface, an improved tilt protection of the impact piece is ensured. The development of the invention according to claim 6 also takes place with a view to reducing the friction.

With the measure according to claim 7 it is achieved that the striker is held captive on the one hand on the end of the cylinder. The diesel ram can thus be implemented as a unit with a hoist. In addition, a stop device that forcibly limits the path of the striking piece in both directions of movement is obtained with little construction effort: sealing collar and guide collar also serve as stop shoulders.

With the development of the invention according to claim 8 ensures that hard impact shocks at the ends of the stroke of Avoid impact piece, sealing collar and guide collar are thus not exposed to impermissibly high impact loads.

The development of the invention according to claim 9 is advantageous in terms of a simple assembly of the striking piece on the cylinder end. In the case of a diesel ram, the cooperating treads of the cylinder and the impact piece can also be easily inspected at the place of use, the piston rings in the outside of the cylinder end can be easily replaced if necessary, and the ring-shaped damper plates can also be easily replaced.

With the development of the invention according to claim 10 it is achieved that the striking piece is guided non-rotatably on the cylinder end. This is not only advantageous in terms of preventing an uncontrolled wandering of the striking element in the angular direction, it is also possible to use the spaces remaining in the angular direction between the guide arms for attaching auxiliary devices on the cylinder outer surface, as stated in claim 14, or for feeding Lubricant to the sliding surface between the sealing collar and impact piece use an axial lubricant supply tube which is placed on the cylinder outer surface, as specified in claim 13.

With the development of the invention according to claim 16 it is achieved that the working area of the diesel ram is essentially inside the cylinder, but it is not necessary to produce the outer surface of the sealing collar exactly coaxially to the cylinder inner surface.

Figur 1:

einen axialen Schnitt durch das untere Ende einer Dieselramme;

Figur 2:

eine seitliche Aufsicht auf das untere Rammenende; und

Figur 3

: einen Schnitt durch die in Figur 1 gezeigte Dieselramme längs der dortigen Schnittlinie III-III, wobei im linken Teil der Schnittansicht Zylinder und Kolben der Ramme weggelassen sind, um Einzelheiten des darunter liegenden Schlagstückes besser zeigen zu können.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawing. In this show:

Figure 1:

an axial section through the lower end of a diesel ram;

Figure 2:

a side view of the lower end of the ram; and

Figure 3

1 shows a section through the diesel ram shown in FIG. 1 along the section line III-III, the cylinder and piston of the ram being omitted in the left part of the sectional view in order to be able to better show details of the striking piece underneath.

The diesel ram shown in FIG. 1 has a cylinder 10 which is open at both ends and in which a piston 12 runs.

The piston 12 has a lower central projection 14 which has a circular flat end face 16.

A working slot 18 is provided in the wall of the cylinder 10 and communicates with a working nozzle 20. The working slot 18 serves to supply fresh air into the interior of the cylinder and to remove the combustion products from the interior of the cylinder.

Opposite the working slot 18, an injection channel 22 is provided in the cylinder wall, which is acted upon by an injection pump 24, which is only shown schematically, with fuel under pressure. The injection pump 24 is actuated mechanically by the falling piston 12, for which purpose it has an actuating lever 28 which can be pivoted about a pin 26. The latter is biased in the radial inward direction by a spring and can protrude through an opening 30 in the cylinder wall into the path of the piston 12. In the drawing, piston 12 is at a point of downward movement reproduced, at which he has just pressed the actuating lever 28 radially outward into the opening 30 so that the injection pump 24 has generated a fuel jet 32.

The fuel jet 32 strikes the circular upper end face 34 of an impact piece designated overall by 36. The end face 34, like the end face 16, is perpendicular to the cylinder axis and has the same diameter as this. It is predetermined by an axially short projection 38 of the striking piece 36, into which a groove 40 is inserted at the edge. The latter serves to collect fuel migrating radially over the end face 34.

The projection 38 is integrally formed on the top of a base 42, which carries a cylindrical peripheral wall 44 of the striker 36 at its edge. The striking piece 36 thus has the overall shape of a cylindrical cup. As can be seen from FIG. 1, the underside 46 of the base 42 has the shape of a spherical cap, so that axial misalignments between the axis of the diesel ram and the axis of a pile 48 48 (pile, pipe or the like) indicated only schematically in FIG. 1 are recorded.

A radially projecting sealing collar 50 is formed on the lower end of the cylinder 10, the lower end face of which coincides with the lower end face of the cylinder. In the outer surface of the sealing collar 50, two axially spaced piston rings 52, 54 are inserted, which are in sliding contact with the inner surface of the peripheral wall 44.

In the upper end of the outer surface of the sealing collar 50 is also a radially open lubrication groove 56, which is connected via a feed bore 58 leading to the upper annular surface of the sealing collar 50 with a feed pipe 60 which extends in the axial direction on the outer surface of the cylinder 10 is fitted and extends through the annular space between the outer cylinder surface and the inner surface of the peripheral wall 44. The second end of the feed pipe 60, which is not shown in the drawing, is connected to a lubricant pump, which is not shown in more detail and which is actuated by the piston 12 when falling down, similarly to the injection pump 24.

At the upper end of the circumferential wall 44, a packet of annular plates is attached by means of screws 62, which consists of an annular stop plate 64, an underlying annular damper plate 66 and an overlying annular damper plate 68. The inner edge of these plates lies at a short distance from the outer surface of the cylinder 10.

The plate stack just mentioned engages radially under the lower annular surface of a guide collar 70, which is formed on the cylinder 10 in the vicinity of the working nozzle 20 and which defines a cylindrical guide surface 72 which represents a continuation of the cylindrical outer surface of the sealing collar 50. Because of this geometry, the said ring plate stack also overlaps the annular upper end face of the sealing collar 50, so that a stop device which specifies both end positions of the striking piece 36 is obtained overall. Due to the movement damping by the damper plates 66, 68, impermissibly high impact loads on the sealing collar 50 and the guide collar 70 are avoided.

A plurality of axial cooling fins 74 distributed in the circumferential direction can be formed on the outer surface of the circumferential wall 44, as indicated by dashed lines in FIG. 1.

As can be seen from FIGS. 2 and 3, four are at the upper end of the peripheral wall 44 at an angular distance of 90 ° arranged guide arms 76 are formed, the curvature and thickness of which corresponds to that of the peripheral wall 44. The guide arms 76 are passed through complementary edge recesses 78 of the stop plate 64 and the damper plates 66, 68. As can be seen from FIG. 3, the plate stack additionally has an inner edge recess 80 through which the feed tube 60 is guided with play. FIG. 3 also shows that the stop plate 64 and the damper plates 66, 68 each consist of two semicircular parts, which are designated 68a and 68b for the upper damper plate.

On the outer surface of the cylinder 10, two axial guide ribs 82, 84 are welded spaced apart in the angular direction in such a way that they cooperate with non-equivalent lateral plane guide surfaces 86 and 88 of the guide arm lying above or below the working nozzle 20 in sliding play, namely the in Figure 3 underlying narrow surface of the guide arm lying above the working nozzle 20 and the narrow surface above of the guide arm lying there under the working nozzle 20. These narrow surfaces each lie in a plane passing through the cylinder axis.

The guide arms 76 thus together with the guide collar 70 provide axial guidance of the striker 36 on the cylinder 10 in a predetermined angular orientation. Due to this special design of the guide device for the striker 36, it is possible to give the striker guide a large axial dimension without an impairment in the choice of location for the working nozzle 20 or the injection pump 24 would have to be mowed. In the free spaces remaining in the angular direction between the guide arms 76, further additional devices can be accommodated, for example a connection between the feed pipe 60 and the lubricant pump.

The diesel ram described above works as follows:

If the piston continues its movement from the position shown in FIG. 1, it runs past the working slot 18 and then forms, together with the striking piece 36 and the lower end of the cylinder 10, a closed working space 90. The air enclosed in this becomes further downward movement strongly compressed and heated accordingly. The downward movement of the piston 12 ends with the striking of its flat end face 16 on the flat end face 34 of the striking piece 36. The striking force obtained in this way is passed on to the pile 48, whereby - as can be seen from FIG. 1 - the transmission distance in the striking piece is very small (Thickness of the bottom 42). The impact energy of the piston 12 is thus transmitted very effectively to the pile 48. This also contributes to the fact that the striker 36 has a low overall mass.

When the piston 12 strikes the striker 36, the fuel located on the end face 34 is atomized at the same time, and the mixture of high-temperature air and fine fuel droplets thus obtained explodes. As a result, the piston 12 is thrown upwards again, and after the working slot 18 has been released, the combustion gases can flow out through the working nozzle 20. When the piston 12 is moved further upwards, fresh air is sucked in via the working nozzle 20, and then when the piston has converted its kinetic energy into potential energy and begins to fall again, a new working cycle begins.

From the above description it can be seen that in the described diesel ram the working space 90 practically extends into the end face of the cylinder 10. No space is required for guiding the striking piece 36 in the axial direction. Rather, the hammer guide is radially outside and provided coaxially to the work space 90. A very good securing of the striking piece 36 against tilting about an axis perpendicular to the cylinder axis is ensured via the guide arms 76, auxiliary units and connecting lines being able to be arranged in the spaces remaining between the guide arms 76. The usable stroke of the guide device is large, so that the ram can also be used to drive rammed material into soft ground. Because of the guide arms 76, the striker tilt protection is still outstanding even if the striker has been moved far down in FIG. 1.

In a modification of the exemplary embodiment described above, a plurality of work sockets 20 can also be provided, each of which is assigned to an intermediate space between guide arms 76. It is also possible to use only two or three instead of four guide arms, or vice versa, a larger number of guide arms.

In a further modification of the exemplary embodiment described above, the piston rings 52, 54 can also be fitted on the inside of the peripheral wall 44 of the striking piece 36 instead of on the outside of the cylinder 10, the outer surface of the cylinder 10 then running smoothly up to the end face.

Claims (16)

1. Diesel ram with a cylinder (10), which comprises an open, lower end, with a piston (12) guided in the cylinder (10), with an impact member (36) guided in a sliding manner through the lower end of the cylinder and sealing the latter, and with means (20 to 30) for the supply, coordinated with the piston movement, of fresh air and fuel into the working space (90) defined by the piston (12), cylinder (10), and impact member (36) and for discharging the combustion gases from the working space (90), in which the impact member (36) is cup-shaped, characterised in that the impact member (36) with its cylindrical peripheral wall (44) travels with a sliding fit (52, 54), sealed with respect to the flow medium, on the outer surface of the cylinder (10).
2. Diesel ram according to Claim 1, characterised in that the outer surface of the cylinder (10) supports a radially projecting sealing collar (50), in which preferably at least one sliding sealing ring (52, 54) is seated.
3. Diesel ram according to Claim 2, characterized in that the sealing collar (50) supports a plurality of sliding sealing rings (52, 54) disposed axially one behind the other.
4. Diesel ram according to Claim 2 or 3, characterised in that the sealing collar (50) extends into the end face of the cylinder (10).
5. Diesel ram according to one of Claims 1 to 4, characterized in that an upper section of the impact member (36) is provided with axial guide arms (76), which travel with a sliding fit on the outside of the cylinder (10).
6. Diesel ram according to Claim 5, characterized in that the guide arms (76) travel with a sliding fit on a guide collar (70), which is supported by the outer surface of the cylinder (10).
7. Diesel ram according to Claim 6, characterised in that at the base sections of the guide arms (76), the impact member (36) is provided with an annular stop plate (64) projecting radially inwards, which may come to bear against the under side of the guide collar (70) and against the upper side of the sealing collar (50).
8. Diesel ram according to Claim 7, characterised in that annular damping plates (66, 68) are located above the end faces of the stop plate (64).
9. Diesel ram according to Claim 7 or 8, characterised in that the stop plate (64) and possibly the annular damping plates (66, 68) are divided along at least one plane passing through the cylinder axis and are located detachably (62) on the upper end of the peripheral wall (44) of the impact member (36).
10. Diesel ram according to one of Claims 5 to 9, characterised by at least two substantially radial guide means (82, 84), extending in the longitudinal direction, which cooperate with associated, non-equivalent side faces (86, 88) of the guide arms (76), in order to secure the impact member (36) against torsion on the cylinder (10) in both directions of rotation.
11. Diesel ram according to one of Claims 2 to 10, characterised in that the sealing collar (50) simultaneously defines a lubricant channel (56).
12. Diesel ram according to Claim 11, characterised in that the lubricant channel (56) is a radially open groove cut in the upper end of the peripheral surface of the sealing collar (50), which groove is connected to a feed bore (58) opening into the upper annular surface of the sealing collar (50).
13. Diesel ram according to Claim 12 in conjunction with Claim 10, characterised by a lubricant supply pipe (60), which extends in the axial direction away from the supply bore (58) and is guided through recesses (80) in the stop plate (64) and possibly in annular damping plates (66, 68).
14. Diesel ram according to one of Claims 10 to 13, characterised in that on the outer surface of the cylinder (10), auxiliary devices, such as injection pump (24), inlet and outlet connections (20), lubricant pump, connecting pipes etc., seen in the peripheral direction, are disposed between the guide arms (76) of the impact member (36).
15. Diesel ram according to one of Claims 1 to 14, characterised in that the outside of the peripheral wall (44) of the cup-shaped impact member (36) is provided with cooling ribs (74).
16. Diesel ram according to one of Claims 1 to 15, characterised in that the base (42) of the cup-shaped impact member (36) comprises a low, central projection (38), which engages with radial clearance in the lower, open end of the cylinder (10).

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