GB2237528A

GB2237528A - Vibration-damped hydraulic hammer

Info

Publication number: GB2237528A
Application number: GB9023615A
Authority: GB
Inventors: Joergen Schou
Original assignee: Breakers AS
Current assignee: Breakers AS
Priority date: 1989-10-31
Filing date: 1990-10-30
Publication date: 1991-05-08
Also published as: DK543289D0; DE9014879U1; GB9023615D0

Abstract

A hydraulic striking tool (1) is encircled by a silencing jacket (7, 8) which is suspended in the vibration-damped handle (5) of the striking tool. By this a reduced natural vibration of the silencing jacket is achieved and consequently an improved noise-suppression. Parts of the jacket which provide an opening for portions of the tool to protrude and an opening for hoses 6 to supply compressed fluid medium, are encircled by rubber bellows. Grip 5 (of rubber or plastic) is mounted on an axle 9 attached to torque arms 13. Arms 13 are attached to traversing axle 19 enclosed by a vibration-damped material 11. Similarly enclosed by material 11 is another traversing axle 19 attached to a vertical supporting bracket 17. A vibration- damped handle is thus formed (see Figure 2). <IMAGE>

Description

HYDRAULICALLY OPERATED STRIKING TOOL, ESPECIALLY A HYDRAULIC HAMMER As indicated in the introduction to claim 1 the invention concerns a hydraulically operated striking tool, in particular a hydraulic hammer, with a striking mechanism which can take up an interchangeable piece of tool, and with a handle which in a vibration-damping way is connected with the striking mechanism.

Such striking tools are applied at contractor's work for breaking up floorings or road surfaces of asphalt, concrete or other hard materials. In these cases a piece-of tool in the shape of a chisel is inserted in the striking mechanism. The striking mechanism can also be designed as a driliing mechanism, for example to be used for mining or in a quarry, and then the tool part will be a drill suitable for boring in rocks. Another possible use is to apply the striking tool as a surface vibrator.

The very striking mechanism of a hydraulic tool of this sort is a very intense source of noise. Every blow of the striking mechanism produces strong vibrations in all parts of the striking tool, and the noise covers a very wide frequence spectrum because the strokes appear as pulses.

Persons working with such a striking tool may get permanent hearing impairment if the noise is too loud. Besides, the noise can be very annoying to the surroundings. Therefore there have been established rules as to how loud the noise may be, according as the working area of the striking tool, its weight, way of application and the shape of the noise spectrum produced.

The purpose of the invention is to provide a hydraulically driven striking tool which gives the operator a better operating convenience in the form of an improved silencing of the tool, compared to that achieved with the known technique.

This is achieved by designing a hydraulic striking tool as indicated in the characterizing part of claim 1.

When the noise-suppressing jacket nearly completely envelops the striking tool and the necessary holes in the jacket are tightened with elastic bellows a direct transmission of sound waves to the surroundings is prevented. As the handle is attached to the jacket the latter follows the movements of the handle which themselves are damped by the operator's grip around the handle. The vibration-damping connection between the handle and the striking mechanism further reduces the vibrations of the jacket and consequently the emission of noise.

It is commonly known to surround pneumatic hammers with a noise-suppressing jacket to damp the noise from the exhaust opening for compressed air. Examples of this known technique are found in the publications EP 147.262 Al and EP 59.071 B1 and also mentioned in DE 30 35 351 Al. The noise-suppressing jackets according to the two firstmentioned publications are clamped around the body of the striking tools and act sound-suppressing by the fact that the outflowing compressed air almost has to pass a labyrinth in order to finally get out into the open through an opening in the jacket, said opening not being necessary for hydraulically driven hammers. In the last-mentioned publication it is stated that the jacket is mounted on the handle and sprung in proportion to the striking mechanism, but nothing about how.

An additional vibration-damping of the handle and thus a better operating convenience is achieved by the arrangement indicated in claim 2. ~ ~ A preferred form of embodiment of the invention is indicated in claim 3.

Below the invention is explained more precisely in connection with a going through a preferred example of embodiment which is shown on the accompanying drawing, where fig. 1 in a partial section shows a simplified picture of a hydraulic hammer according to the invention, fig. 2 is a partial cross-section shows the design of a vibration-damped handle very suitable for the mounting of a silencing jacket according to the invention, fig. 3 in a partial section shows the hose connection for the striking mechanism, fig. 4 shows a section through the bottom part of the noise-suppressing jacket and fig. 5 shows a section through a bellows which comprises the coupler for tools.

The hydraulic hammer 1 according to the invention and shown in fig. 1 consists of a striking mechanism 2, which is only shown schematically and equipped with a coupler 3 in which the chisel 4 is coupled. The hammer is fitted with a vibration-damped handle 5 and it is supplied with a compressed medium, in this case a hydraulic oil, through two hoses 6 and coming from a supply unit (not shown). The chief part of the striking mechanism 2 is encircled by a noise-suppressing jacket 7 which is shown in a sectional view and is attached to the vibration-damped handle 5.

The operator holds the hammer by the handles 5 and presses the chisel downwards against the working spot.-The vibration-damped handle 5 and consequently the silencing jacket 7 hereby stand comparatively still, whereas the striking mechanism 2, the coupler 3, the chisel 4 and the hose connection 6 are vibrating rather violently because of the strokes generated by the striking mechanism 2.

Therefore there is radiated comparatively less noise from the surface of the silencing jacket 7 than from the surface of the striking mechanism 2. The noise radiation from the striking mechanism 2 is damped by e.g. a rock wool coating 8 or a similar strongly silencing material on the inner side of the noise-suppressing jacket 7.

Seen from the surroundings the greater part of the surface of the hammer is constituted by the surface of the silencing jacket 7. As the latter stands more still than the striking mechanism 2 it results in a lower radiation of noise than that from the naked striking mechanism 2.

Fig. 2 shows on a larger scale and in a partial section a handle design where the very handle grip 5 of rubber or plastic is mounted on a hand part in the shape of a axle 9 which is attached to the torque arms 13. The torque arms are attached to the traversing axle 19, which is enclosed by a vibration-damping material 11, bearing the housing 12.

In the opposite part of the housing 12 and likewise enclosed by vibration-damping material 11 there is also placed a traversing axle 19, attached to the vertical supporting bracket 17. By this a strongly vibration-damped handle 5 is produced. The axle 9 in all essentials will be at rest when the striking tool is in use but the vertical supporting arms 17 will move and by that bend the torque arms 13 and tilt the housing 12 around the axle 9. A line stretched from the axle 9 in the direction of the working spot thus will intersect the plane, in which the axes of the rubber bodies are situated, somewhere between said axes. The silencing jacket is attached to the handles 5.

Said vibration-damped attachment of the handles to the striking mechanism has the additional advantage that there will only be parallel displacements when the handle is moving, which implies that the operator can keep a good contact with the tool in spite of the vibration-damping design.

Fig. 3 is a sectional view of a hose connection for a compressed medium, where a pressure hose 6 is enclosed by a bellows 14 or the like of rubber or a similar elastic material, so that noise from the striking mechanism 2 cannot be radiated through the opening.

Fig. 4 is a sectional view of the bottom part of the jacket 7 which by means of a sleeve 15, e.g. made of a plastic, is guided glidingly around the very striking mechanism not shown. Around the lower jacket is mounted a bellows 16, which is seen more clearly in fig. 5, and said bellows 16, made of an elastic material such as rubber or plastic, encloses the entire connecting between the silencing jacket 7 and the coupler 3 for the tool 4, and also secures against radiation of noise from the striking mechanism and from the coupler, and by this contributes much to limiting the radiation of noise from the hydraulic hammer.

Claims

1. A hydraulically operated striking tool (1), in particular a hydraulic hammer, with a striking mechanism (2) which can take up an interchangeable piece of tool (4) and with a handle (5) connected with the striking mechanism ina vibration-damping way, c h a r a c t e r i z e d i n that the striking tool (1) is equipped with an surrounding jacket (7) which has a first opening for connecting striking mechanism with the very tool and a second opening for hoses supplying the striking mechanism with a compressed medium and where the jacket (7) is attached to the handle (5) and besides entirely surrounds the striking mechanism, and that the parts of the jacket adjoining the openings are shaped as bellows (14,16) of a flexible material where the handle (5) is attached to an axle (9) which by a first body of rubber or a similar material is connected with an intermediate piece which again by another body of rubber or a similar material is connected with the striking mechanism, the rubber bodies being axially symmetric and placed so that their axes are parallel in a plane which extends traversely to the direction in which the striking tool is pressed against a location to be worked on, and where the handles and the intermediate piece are connected with the first rubber body in such a manner that they under a torsional strain on the latter are mutually rotated around the axis of the other rubber body when the striking tool is pressed against the working location, that the handles comprise an essentially axially symmetric hand part extending parallely to the axes of the rubber bodies, said hand part being connected with the first rubber body by the axle (9), that the hand part is placed so in relation to the rubber bodies that a line stretched out from the longitudinal axis of the hand part in the direction of the working location intersects the plane in which the axes of the rubber bodies is situated between said axes, and that the silencing jacket is fitted on the hand part.

2. Hydraulically operated striking tool according to claim 1, c h a r a c t e r i z e d i n that the jacket is designed with at least one handle piece surrounding the hand part while a layer of an elastomer is placed between the handle piece and the hand part.

3. Hydraulically operated striking tool according to one of the preceding claims, c h a r a c t e r i z e d i n that the jacket is designed integral with the handle.

4. Hydraulically operated striking tool as shown and described in the description and drawing.