Pile hammer

Abstract

A pile hammer includes a cylinder, a piston displaceably guided in the cylinder, and a striker displaceably guided in the cylinder. The striker is disposed underneath the piston in the operating position of the pile hammer. A combustion chamber is delimited axially by a face surface of the striker that lies in the interior of the cylinder and by a face surface of the piston. Using at least one fuel feed device a predetermined amount of fuel can be introduced into the combustion chamber during each working cycle. A primary fuel feed device is provided, which includes a primary fuel nozzle connected with a primary fuel tank having a fuel with great anti-knock properties. The primary fuel nozzle is structured as a high-pressure injection nozzle. An ignition oil feed device is also provided, which includes an ignition oil nozzle connected with an ignition oil tank having an ignition oil. The ignition oil nozzle is structured as a low-pressure injection nozzle. A method operates such a pile hammer.

Claims

1. A pile hammer comprising: (a) a cylinder having an interior; (b) a primary fuel tank having a fuel with anti-knock properties; (c) an ignition oil tank having an ignition oil; (d) a piston displaceably guided in the cylinder and having a piston face surface; (e) a striker displaceably guided in the cylinder and disposed underneath the piston in an operating position, said striker having a striker face surface lying in the interior of the cylinder; (f) a combustion chamber delimited axially by the striker face surface and by the piston face surface; (g) a primary fuel feed device comprising a primary fuel nozzle structured as a high-pressure injection nozzle connected with the primary fuel tank for introduction of a predetermined amount of the fuel into the combustion chamber during each working cycle; and (h) an ignition oil feed device comprising an ignition oil nozzle structured as a low-pressure injection nozzle connected with the ignition oil tank.

2. The pile hammer according to claim 1, wherein the ignition oil nozzle is configured so that the ignition oil is applied to the striker as a jet.

3. The pile hammer according to claim 1, wherein the primary fuel nozzle is configured so that the fuel from the primary fuel tank is introduced into the combustion chamber as an atomized fuel mist.

4. The pile hammer according to claim 3, wherein the primary fuel nozzle is disposed so that the fuel mist is introduced into the combustion chamber near the striker face surface, orthogonally to a movement direction of the piston.

5. The pile hammer according to claim 1, wherein the primary fuel nozzle and the ignition oil nozzle are disposed at different vertical distances from the striker.

6. The pile hammer according to claim 5, wherein the ignition oil nozzle is disposed above the primary fuel nozzle, viewed from the striker.

7. The pile hammer according to claim 1, wherein the primary fuel nozzle and the ignition oil nozzle are connected with first and second pump devices, respectively, wherein the first and second pump devices are controllable by dropping the piston.

8. The pile hammer according to claim 7, wherein at least one of the first and second pump devices has a pump lever that projects into the interior of the cylinder 1 and is configured and oriented so that the pump device is activated when the piston drops past the pump lever, thereby initiating an injection process.

9. A method for operating a pile hammer comprising a cylinder having an interior, a primary fuel tank having a fuel with anti-knock properties, an ignition oil tank having an ignition oil, a piston displaceably guided in the cylinder and having a piston face surface, a striker displaceably guided in the cylinder and disposed underneath the piston in an operating position, the striker having a striker face surface lying in the interior of the cylinder, a combustion chamber delimited axially by the striker face surface and by the piston face surface, a primary fuel feel device comprising a primary fuel nozzle structured as a high-pressure injection nozzle for introduction of a predetermined amount of fuel into the combustion chamber during each working cycle, and an ignition oil feed device comprising an ignition oil nozzle structured as a low-pressure ignition nozzle connected with the ignition oil tank, said method comprising: (a) during each work cycle, activating a fuel pump by dropping the piston to cause the fuel with anti-knock properties to be introduced into the combustion chamber and by way of the primary fuel nozzle, thereby forming a primary fuel/air mixture in the combustion chamber; (b) activating the ignition oil pump to spray an amount of ignition oil onto the striker by way of the ignition oil nozzle; and (c) atomizing and igniting the ignition oil when the piston impacts the striker to cause ignition of the primary fuel/air mixture to take place.

10. The method according to claim 9, wherein the fuel with the anti-knock properties and the ignition oil are introduced into the combustion chamber at different times.

11. The method according to claim 10, wherein an ignition oil puddle forms from the amount of ignition oil sprayed onto the striker, and afterward, the fuel with anti-knock properties is introduced into the combustion chamber as an atomized fuel mist, before the ignition oil situated on the striker is atomized and ignited as a result of the piston impacting the striker.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

(2) In the drawings:

(3) The single FIGURE shows a schematic representation of a pile hammer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(4) Referring now in detail to the drawings, the pile hammer shown in the sole FIGURE selected as an exemplary embodiment comprises a cylinder 1 that is open on both sides, and regularly can have a length of 3 to 8 meters and a diameter of 0.2 to 1.5 meters. A piston 2 is displaceably disposed in the cylinder 1. A striker 3 coaxial to the piston 2 engages into the open lower end of the cylinder 1, in displaceable manner. A ring-shaped bearing unit 9 is attached at the lower end of the cylinder 1, in which unit a central shaft section 31 of the striker 3 is guided in tight and displaceable manner. Central shaft section 31 has an outside diameter that is reduced as compared with the inside diameter of the cylinder 1. The pile hammer is mounted so as to be vertically displaceable along a leader 8, by way of guide jaws 13 disposed on the cylinder 1.

(5) A strike plate 32 is formed onto the lower end of the shaft section 31, lying underneath the cylinder 1, the lower convex delimitation surface 33 of which plate, directed outward, interacts with the upper end of a material to be pile-driven, during operation.

(6) A piston section 34 having multiple circumferential sealing rings, axially at a distance from one another, which run on the inner mantle surface 11 of the cylinder 1, is formed on at the upper end of the shaft section 31 of the striker 3. A combustion chamber 12 is delimited by the top of the piston section 34 of the striker 3, together with the underside of the piston 2, as well as the inner mantle surface 11 of the cylinder 1. The face surface of the striker 3 that faces the combustion chamber 12 of the cylinder 1 is ground to be level with a flat fuel bowl.

(7) A damping ring 91 is disposed between the strike plate 32 of the striker 3 and the bearing unit 9 of the cylinder 1. A further damping ring 92 is disposed adjacent to the bearing unit 9, between the top of the bearing unit 9 and the underside of the piston section 34 of the striker 3.

(8) A lower working end 23 of the piston 2, provided with circumferential sealing rings 93 that are axially spaced apart from one another, runs in the interior of the cylinder 1, above the striker 3. The lower, free face surface 21 of the piston 2, ground to be planar, is set off by a circumferential step that lies radially on the outside.

(9) A mass section 22 that extends into the upper section of the cylinder 1 is formed onto the lower working end 23 of the piston 2. A primary fuel feed device 4 is disposed on the circumference wall of the cylinder 1. This primary fuel feed device 4 comprises a primary fuel pump 41 that is connected with the primary fuel nozzle 42, configured in the form of a high-pressure injection nozzle, by way of a line. The primary fuel pump 41 is supplied with a fuel having great anti-knock properties, ethanol in the present case, by way of a primary fuel tank 45. In place of ethanol, natural gas, LPG, biogas, super-gasoline or E85 fuel (gasoline-ethanol mixture with 85 percent ethanol proportion), for example, can also be used.

(10) The primary fuel pump 41 connected with the primary fuel tank 45 by way of a line has a biased pump lever 44 that projects into the interior of the cylinder 1, by way of which the pump is driven when the dropping piston 2 goes past. The primary fuel feed device 4, particularly its primary fuel nozzle 42, is configured and oriented in such a manner that the primary fuel emitted is sprayed into the combustion chamber 12 essentially as a finely atomized mist.

(11) Furthermore, an ignition oil pump 51 that is driven by means of a pump lever 54 biased into the interior of the cylinder 1 when the piston 2 drops is connected with an ignition oil nozzle 52 configured as a low-pressure injection nozzle, by way of a line, on the conveying side, and forms an ignition oil feed device 5 together with this nozzle. The ignition oil pump 51 communicates with an ignition oil tank filled with diesel oil used as the ignition oil. The ignition oil feed device 5 is disposed on and in the circumference wall of the cylinder 1, axially at a distance from the primary fuel feed device 4 in the direction toward the upper end of the cylinder 1. Its ignition oil nozzle 52 is configured and oriented in such a manner that the ignition oil emitted is sprayed approximately centrally along line 53 onto the face surface of the striker 3, in the form of an essentially cohesive jet.

(12) The configuration of the primary fuel pump 41 and the ignition oil pump 51, with a respective pump lever 44, 54 provided, projecting into the cylinder 1, essentially corresponds, in the exemplary embodiment, to the embodiment of the fuel pumps of the low-pressure injection apparatus described in WO 2006/072297 known from the prior art. For this reason, reference is made to the explanations contained in this document, at this point, with regard to these pumps.

(13) Furthermore, a lubricant pump 7 is provided on the cylinder 1, which is connected with lubricant nozzles distributed in the circumference direction of the cylinder 1. Lubricant is applied between the piston 2 and the inner mantle surface 11 of the cylinder 1 by the lubricant nozzles.

(14) The pile hammer described above works as follows: In the starting state, the piston 2 is raised into an upper position by way of the disengagement apparatus—not shown. After disengagement, it falls downward from there, under the effect of gravity, closes the working connectors 16, and, one after the other, activates the pump levers 54, 44 of the ignition oil feed device 5 and the primary fuel feed device 4 with its face surface 21. As a result, first jet-like application of a small amount of ignition oil onto the striker 3, forming a puddle there, takes place. Subsequently, the primary fuel, ethanol in the present case, is injected into the combustion chamber 12 in atomized form, by way of the primary fuel nozzle 42, which fuel is thereby mixed with air and compressed by way of the dropping piston 2. When the piston 2 impacts the striker 3, the ignition oil puddle is atomized and auto-ignited, thereby causing ignition of the compressed primary fuel/air mixture 6 to take place.

(15) When the piston 2 impacts the striker 3, a force directed downward is more or less exerted on the striker 3 and, by way of the striker 3, on the material to be pile-driven, which force drives the material to be pile-driven further into the ground. During the subsequent upward movement of the piston 2, triggered by the explosion-like combustion of the primary fuel, the piston releases the working connectors 16 again, thereby causing the combustion gases to relax and to flow away by way of the working connectors 16. The piston 2 is now accelerated further upward, drawing fresh air in through the working connectors 16, until it has reached its upper end position and the work cycle, as described, is repeated.

(16) Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.