WO2003008156A1

WO2003008156A1 - Hydraulic hammer with a piston and a cyliner which move in anti-phase

Info

Publication number: WO2003008156A1
Application number: PCT/DK2001/000445
Authority: WO
Inventors: Esben Vadstrup
Original assignee: Breakers A/S
Priority date: 2001-06-26
Filing date: 2001-06-26
Publication date: 2003-01-30

Abstract

The invention relates to a hydraulic hammer (1) comprising an engine housing (2) with a cylindrical bore (3) in which a piston (4) is arranged in an axially displaceable manner, said piston (4) transferring kinetic energy to an auxiliary tool (5), and means for oil supply (8) and also for the establishing of a pressure in the engine housing (2), said pressure bringing about the movement of the piston (4) and also coupling to an energy source, and where said hammer (1) further comprises a hammer body (9), said hammer body at least surronding the engine housing (2), and where said engine housing (2) is flexibly coupled by first means (10') to the hammer body (9), and that the hammer body (9) comprises a handgrip (11) in the area opposite the auxiliary tool (5). There is hereby achieved a hydraulic hammer which does not have the disadvantages of existing products, and where a very low level of vibration is achieved, corresponding to less than 2 1/2 m per sedond2, and further also a particularly low noise level due to the resulting construction, and finally a simple manufacturing of the product as a result of the number of components being considerably reduced and can be produced as integrated units.

Description

HYDRAULIC HAMMER WITH A PISTON AND A CYLINER WHICH MOVE IN ANΗ-PHASE

HYDRAULIC HAMMER

The invention relates to a hydraulic hammer comprising an engine housing with a cylindrical bore in which a piston is placed in an axially displaceable manner, said piston transferring kinetic energy to an auxiliary tool, and means for the supply of oil and also the establishing of a pressure in the engine housing, said pressure bringing about the movement of the piston and also coupling to the source of energy.

Such a hydraulic hammer is known, for example, from Swedish patent publication no. 505601 , which is provided with an engine housing with an axially displaceable piston. In the engine housing itself there are also provided intermediate walls which are filled out with a noise-suppressing material, so that noise from the hammer is reduced to a certain degree. This noise re- duction will not, however, be satisfactory, the reason being that the noise can escape in areas other than in just the insulated area. Moreover, the construction will also give rise to strong vibrations for the user, in that with this construction no solution is provided for the very well-known problem that vibrations are transferred from the product to the user, for example in connection with the breaking-up of concrete, asphalt and the like.

The objects of the present invention are thus to provide a hydraulic hammer which is not encumbered with the disadvantages of the existing products, and where a very low level of vibration is achieved, corresponding to less than 2¹/2 m per second² , and furthermore also a particularly low level of noise as a consequence of the resulting construction, and finally a simple manufacturing of the product in that the number of components is considerably reduced and can be produced as integrated units.

This object is achieved with a hydraulic hammer of the kind disclosed in the introduction, and further where the hammer also includes a hammer body which at least surrounds the engine housing, and where said engine housing is connected in a flexible manner by first means to the hammer body, and the hammer body comprising a handgrip in the area opposite the auxiliary tool. As a consequence of the hydraulic hammer thus being en- closed in an outer jacket, the noise will naturally be strongly reduced, in that the jacket in itself serves to suppress noise. What is of further importance is the flexible suspension of the engine housing in the heavy outer jacket, so that the transferred vibration is considerably reduced.

During use, the piston will thus start at the bottom when the oil is connected. There is a high pressure on the underside of the piston and a low pressure of approx. 10 bar over the top of the piston, while the high pressure or working pressure lies at around 120 bar. The piston moves at almost constant speed up to its uppermost reversing point. Thereafter, the pressure over the piston will be changed from the tank pressure 10 bar to the working pressure 120 bar, whereby the piston accelerates quickly downwards. At the same time that the piston accelerates downwards, the effect of the pressure is that the engine housing accelerates upwards. The engine housing is hereby lifted up from the auxiliary tool, for example in the form of a chisel. However, this movement of the engine housing is absorbed by the spring, and whereby the spring naturally influences the hammer body, but the movement of the hammer body is only marginal. A damping of the vibration is hereby achieved, so that the user will not experience the strong vibrations. The piston reaches the maximum speed immediately before the auxiliary tool is hit. The kinetic energy is transferred to the chisel, and the piston is braked. The pressure is changed yet again and the piston is driven upwards again as the start of a new cycle. At the same time that the piston is driven upwards, the engine housing is pressed down against the chisel by the weight of the engine housing and the power of the spring. Since the handgrip is mounted directly on the hammer body, i.e. there is no link between the handgrip and the hammer body, the hand- grip becomes a part of the hammer body and vibration-damping arrangements are not necessary on the handgrip itself, as is otherwise normally the case. Furthermore, a construction such as that disclosed can in itself result in the hammer body constituting a considerable weight. The large mass is thus insulated from the actual engine housing, and is instead transferred to the stationary part, i.e. the hammer body itself.

By providing a hydraulic hammer according to the invention and as disclosed in claim 2, an expedient transfer of the force is achieved during the movements of the engine housing.

By providing a hydraulic hammer according to the invention and as disclosed in claim 3, it is achieved that the weight of the hammer body is increased so that the vibration damping is intensified. The external source of energy is preferably a pump which pumps oil to the hammer. In the cases where an excess of oil is pumped in, this is stored in the accumulator and used later.

By providing a hydraulic hammer according to the invention and as dis- closed in claim 4, a precise control of the piston is achieved in the engine housing itself.

By providing a hydraulic hammer according to the invention and as disclosed in claims 5, 6 and 7, an expedient construction is achieved for bringing about the differences in pressure over the piston when this is to be activated.

By providing a hydraulic hammer according to the invention and as disclosed in claim 8, an expedient distribution of weight is achieved between the hammer body and the remaining components, so that the vibration damping is increased. The invention will now the explained in more detail with reference to the drawing, where

fig. 1 shows a section through an example embodiment according to the invention, fig. 2 shows the movement pattern for the piston, fig. 3 shows the supply of oil in principle, fig. 4 shows the position of the slide when the piston is in the top position, fig. 5 shows the position of the slide when maximum pressure is applied to the piston for acceleration of the piston towards the auxiliary tool.

Figure 1 shows a section through a hammer 1 , comprising an engine housing 2 in which there is a cylindrical bore 3 for the accommodation of a piston 4 which is axially displaceable. The free end surface 7 of the piston lies in the area opposite the construction's handgrip 11. By the axial movement of the piston 4, the kinetic energy will be transferred to an auxiliary tool 5, for example in the form of a chisel. The auxiliary tool is guided by a connection element 6. Where this part is concerned, the construction of the apparatus follows known principles.

The engine housing 2 itself is surrounded by a hammer body 9, and where the hammer body 9 as mentioned at least surrounds the engine housing itself, but possibly also parts of the area where the piston has its clearance, and possibly part of the auxiliary tool. In the area opposite the free surface of the piston, the hammer body 9 also has a handgrip 11 which thus constitutes an integral part of the body 9. The hammer body 9 has connection and passage 8 to an oil pump/energy source, from which oil is pumped into a third chamber 19 where there is a working pressure of around 120-130 bar. From this third chamber there is a first channel 18 which connects the chamber to a second chamber 16 when the slide is in its first position, said second chamber 16 lying between the outer surface of the piston 4 and the inner surface of the engine housing 2 and being limited by an axially dis- placeable slide 17, and where this slide/cylindrical sleeve has a first and a second position.

When the slide assumes its first position, which appears from fig. 4, connection will be established from the second chamber to a so-called tank chamber 15 which lies in the area between the inner surface of the body 9 and the outer surface of the housing. In this tank chamber there is a pressure of approx. 10 bar. The connection takes place by means of a second channel 20. When the slide 17 assumes a second position, which appears from fig. 5, there is instead established a connection between the second chamber 16 and the oil-filled third chamber 19, said third chamber as mentioned having a pressure of around 120 bar, a so-called working pressure.

Moreover, there is a third channel 21 which connects the third chamber 19 to a fourth chamber 22 which lies at a distance from the other chambers and in the area closer to the free surface of the piston. The pressure in this chamber will thus always assume working pressure. Between this fourth chamber 22 and said second chamber, there is a first control chamber and a second control chamber, said first control chamber 23 and said second control chamber 24 being placed in a circular manner as an annular ring chamber between the outer surface of the piston and the inner surface of the engine housing.

In the first control chamber 23 there will be a pressure t, while the pressure in the second control chamber 24 will depend on the position of the piston and the time in the cycle. When there is connection between the first control chamber 23 and the second control chamber 24 via the chamber 28, which lies around the piston, the pressure in the second control chamber 24 is t. The pressure in the second control chamber 24 changes to p at the moment that the piston is driven upwards and the edge 29 of the piston opens for connection between the chamber 22 and the second control chamber 24. The pressure p in the second control chamber 24 causes the slide to take up its second position and open for connection between the chamber 19 and the chamber 16. The pressure p in the chamber 16 causes the piston to move downwards, and the pressure in the second control chamber 24 remains p until the chamber 28 forms connection between the first control chamber 23 and the second control chamber 24. The slide assumes its first position again when the pressure in the second control chamber 24 becomes t. The pressure in the second control chamber 24 remains t until connection is opened again between the second control chamber 24 and the chamber 22.

Finally, the engine housing 2 itself is suspended in first means in the form of springs 10, 10', preferably as helical springs. As mentioned, these springs connect the engine housing 2 with the hammer body 9, where in this case use is made of two springs, i.e. a spring placed between a projecting collar 25, the first collar, on the engine housing itself, and a collar 26, the second collar, on the hammer body 9, and a spring placed between the collar 31 on the engine housing and collar 30 on the hammer body. The springs are mounted in such a manner that they are pre-stressed and, to- gether with the guides, ensure that there is no contact between the engine housing and the hammer body. The two springs are thus active in opposite directions, in that the first spring 10' is compressed, whereby the compression of the second spring 10 is reduced, and vice versa. The hammer body also comprises elements, such as an accumulator 14, which increases the weight of the body itself. With reference to figure 2, there is seen a principle diagram for the movements of the piston. The piston starts in bottom position when the oil is supplied. There is a working pressure p on the underside of the piston, and tank pressure t on the top of the piston. The piston is driven at almost constant speed up to the uppermost reversing point. The pressure over the piston is changed from t to p and the piston accelerates quickly downwards. At the same time that the piston accelerates downwards, the pressure causes the engine housing to accelerate upwards. The engine housing is hereby lifted up from the chisel.

The movement of the engine housing is absorbed by the spring. The spring influences the hammer body, but the movement of the hammer body is only marginal due to the great inherent weight of the hammer body. The piston reaches the maximum speed immediately before the auxiliary tool is hit. The kinetic energy in the piston is delivered to the chisel, whereby the piston is braked. The pressure is changed again and the piston is again driven upwards as the start of a new cycle. At the same time that the piston moves upwards, the engine housing is pressed back to the chisel by the weight of the engine housing and the force from the spring.

The supply of oil to the hammer mechanism will now be explained with reference to figure 3. The oil is led into the hammer body and via two chambers over into the engine housing itself. In the engine housing, the oil is led to the one end of the slide, which is controlled by the position of the piston. The result is that the oil can be transferred to the engine housing, even though the engine housing is displaced into the hammer body.

Claims

1. Hydraulic hammer (1) comprising an engine housing (2) with a cylindrical bore (3) in which a piston (4) is placed in a manner in which it can be displaced axially, said piston (4) transferring kinetic energy to an auxiliary tool (5), and means for oil supply (8) and also for establishing pressure in the engine housing (2), said establishing of pressure bringing about the movement of the piston (4) and also coupling to the source of energy, characterised in that the hammer (1) further comprises a hammer body (9), said hammer body at least enclosing the engine housing (2), and said engine housing (2) being flexibly connected by first means (10') to the hammer body (9), and that the hammer body (9) comprises a handgrip (11) in the area opposite the auxiliary tool (5).

2. Hydraulic hammer according to claim 1, characterised in that the first means comprise springs, preferably helical springs (10').

3. Hydraulic hammer according to claim 1 or 2, characte rised in that the hammer body (9) also comprises an accumulator (14).

4. Hydraulic hammer according to any of the foregoing claims, c h a r a c t e r i s e d in that this comprises guides/guide surfaces (13) in the area between the inner surface of the hammer body (9) and the outer surface of the engine housing (2).

5. Hydraulic hammer according to any of the foregoing claims, c h a r a c t e r i s e d in that in an area between the outer surface of the engine housing (2) and the inner surface of the hammer body (9), there is an annular oil-filled tank chamber (15) and with a pressure T.

6. Hydraulic hammer according to any of the foregoing claims, c h a r a c t e r i s e d in that in a second chamber (16), preferably arranged in the area at the handgrip (11), a cylindrical and axially displaceable slide (17) is inserted between the outer surface of the piston (4) and the inner surface of the engine housing (2).

7. Hydraulic hammer according to claim 6, c h a r a c t e r i s e d in that the slide (17) assumes two end positions, a first position and a second position, at which said first position the second chamber communicates by a first channel (18) with an oil-filled third chamber (19) with a pressure p and greater than t, and which at said second position the second chamber (16) communicates via a second channel (20) with the tank chamber (15).

8. Hydraulic hammer according to any of the foregoing claims, c h a r a c t e r i s e d in that the hammer body (9) is produced in a metal, preferably an alloy.