Hammering device

Hammering device functioning with pressure fluid of a hydraulic arrangement which hammering device comprises a body (16), (19) which can be attached to a working machine on which machine a hammering mass (3) is adjusted to be resting and to be moving which hammering mass is moved into a hammering position with the help of hydraulic pressure by directing the pressurized fluid into the ring-shaped, first chamber space (6) wherein the hammering mass (3) when it is moving into a hammering position compresses gas in the chamber space (K1) located at the first side of the hammering mass (3) and in order to perform the hammering movement with the hammering mass (3) to the hammering element (5), (27) the flow of hydraulic pressure is blocked to the first chamber space (6) and the access for pressure fluid is allowed away from the first chamber space (6) with the help of the valve (2). In order to remove the pressure fluid fast from the first chamber space (6) the ring-shaped, second chamber space (7) is adjusted to be an extension for the first chamber space (6) and a ring-shaped valve (2) which comprises a closing ring is adjusted between the mentioned chamber spaces (6), (7) the port of which valve is formed of a group of holes which holes are located in the mentioned closing ring.

This invention relates to a hammering device functioning with pressure fluid of a hydraulic system which hammering device comprises a body which can be attached to a working machine on which machine a hammering mass is adjusted to be resting and moving which hammering mass is moved to a hammering position with the help of hydraulic pressure by directing the pressurized fluid to a ring-shaped, first chamber space in which case the hammering mass compresses the gas when it is moving to the hammering position in a chamber space which is located at the first side of the hammering mass and in order to perform the hammering movement with the hammering mass to the hammering element the flow of the hydraulic pressure to the first chamber space is blocked and the exit for the pressure fluid is allowed with the help of a valve from the first chamber space.

A rotating ring valve which is adjusted to a hydraulic hammering device is previously known from the publication SU 423922 in which publication the ring valve which rotates with a constant speed adjusts the stroke frequency of the hammering device. The stroke frequency can be adjusted by blocking ports with special pegs. The ring valve controls out/return flows of the pressurized liquid along pipings into a cylinder to the pressure face of the hammering piston. Gas which is compressed at the other side of the plunger performs the hammering work when the ring valve enables the removing of the liquid from the cylinder. Thus a pulsating movement can be created for the piston. The ring valve does not decrease the pressure losses being created in the pipings. During the hammering the liquid is removed from the cylinder along a channel system and causes pressure loss and weakens hammering efficiency.

In the publication FI116513 the ring valve functions as a closing and opening valve of the pressure channel in the hammering device. There is a control valve which is installed to be rotating in the hammering device which control valve comprises control channels in order to direct the pressure fluid periodically from the pressure fluid space to the return channel. In this solution the hammering movement is created by allowing the access from the pressure fluid space to the fluid container. The return piping causes a huge pressure loss because a fast hammering movement would demand fast flow rate of the liquid in a conventional return piping. With this solution an efficient hammering action cannot be achieved.

A rotating ring valve which is located in a vibrating device creating trembling is shown in the publication U.S. Pat. No. 4,317,406. The piston creating trembling moves in the cylinder when the direction of motion of the piston is being changed all the time with the help of the rotating ring valve. Because a pressure accumulator is not used in order to intensify the impacts of the piston, the flow resistance of the return channel is really not of significance.

The disadvantage of the above mentioned solutions is flow resistance caused by the liquid which is being removed from the front of the piston during the impact when the liquid must run through the piping into the fluid container. When a pressure accumulator is used in order to intensify the impacts, the liquid should run in the return pipe 10, even 20 times faster in relation to the normal flow rate. This is nearly impossible and the consequence is that one cannot reach the impact velocity which potentially could be gained.

With the hammering device according to the invention essential improvements can be achieved in relation to the known prior art and it is characteristic of the invention that in order to remove the pressure fluid fast from the first chamber space a second, ring-shaped chamber space has been adjusted to be an extension for the first chamber space and a ring-shaped valve, which comprises a closing ring, has been adjusted between the mentioned chamber spaces the port of which valve has been formed of a group of holes which are located in the mentioned closing ring in which case the pressure fluid is adjusted to move fast from the first chamber space to the second chamber space through the mentioned valve when the mentioned volumes of the chamber spaces are changing due to the movement of the hammering plunger.

The advantage of the invention is the fact that the counter pressure caused by the hydraulic fluid which is being removed fast from the cylinder can be nearly eliminated with the help of a new valve when the liquid can be directed immediately to the adjacent space through the holes of the valve. When the hammering mass is being moved to be ready for the impact, the hydraulic fluid is being removed through the pipeline but this removal does not need to be a sudden process. The new valve can be built in such a way that it functions fast and in spite of that all pressure impact effects which are created stay to be harmless in the chamber spaces of the device. The valve according to the invention can be used in the percussion hammers which hit in one direction, such as in breaking hammers for stones and in hammering devices which hit in two directions, such as in devices which hit poles into the ground and pull them up.

A hammering device which can be attached to a working machine with an attachment part18is shown in theFIG. 1which hammering device comprises a attachment body19and a body of the hammering device16which is adjusted inside it with the help of a rubber damper27.

The same hammering device is shown in theFIG. 2as a section view in which case a cylindrical body of the hammering device16comprises a hammering piston3inside it as a hammering mass and it this case comprises a shaft bar5which is directed through a hammering piston3which shaft bar directs the impacts to be created out of the device. The hammering mass/piston3is sealed onto the inner surface of the body of the hammering device16. A ring-shaped chamber space is formed for the side part of the hammering piston3by decreasing the size of the diameter which chamber space is divided into two chamber space6and7with the help of a valve2which is attached to the body of the hammering device16. The shaft bar5comprises two flange parts8and12which are sealed onto the inner surface of the body of the hammering device16and the mentioned flanges8,12divide the inner space of the body of the hammering device16further into chambers K1, K2, K3and K4. These chambers can be filled with gas. Hydraulic pressure fluid is led in a controlled way into the chamber spaces6and7through a valve1and out of the chamber spaces as a return flow.

The hammering device functions as a unit which hits downwards by directing the pressure, which lifts the hammering piston3upwards, from the valve1to the chamber space6. At the same time the pressure fluid is being allowed to burst out from the chamber space through a valve1. When the hammering piston3is being lifted, the gas is compressed in the chamber K1and at the same time also in the chamber K2and also the shaft bar5rises a little bit. With the help of the working machine the hammering device is being pressed or it is let to be pressed against the target in such a way that the lower end of the shaft bar5will be attached to the target of the impact. With a regulated pressure of the chamber K1the functioning of the valve1is changed to block the feeding into the chamber space6. At the same time a ring-shaped valve2is being opened between the chamber spaces6and7in which case the pressure of the gas in the chambers K1and K2suddenly pushes the hammering piston3downwards and it hits the shaft bar to the flange8. The valve2lets the hydraulic fluid to flow from a chamber space6which is suddenly getting smaller to a correspondingly expanding chamber space7. A part of the hydraulic fluid returns through the valve1into the fluid container, but the largest part of the liquid moves through the valve2into the expanding chamber7which expands in the same proportion as the chamber6is getting smaller. The hammering piston3hits the flange8before the movement play of the hammering plunger3finishes. The device hits again when the hammering piston is being lifted up again with the help of the pressure which is directed to the chamber space6.

The impacts upwards occur by being controlled with the valve1by directing the hammering piston3down with the help of a hydraulic pressure which is directed into the chamber space7in which case the hammering piston at the same time compresses the gases of the chambers K3and K4into a high pressure to be the loading energy for the impact. However before the changing of the hammering direction the gases of the chamber K1must be led into the chamber K3for the most part. This can be done by directing the hammering piston3so high and directing such a great pressure into the chamber K1that the valve10, which is adjusted to become open with a pressure which is greater than in normal use, becomes open and lets the most part of the gas of the chamber K1into the chamber K3from the side of the arm of the shaft bar5. In this way the needed, greater gas volume is being changed into the chamber K3. When the hammering direction is being returned, the gas is being led correspondingly back into the chamber K1through a valve11which is being opened with a certain pressure.

The valve2according to the invention is shown in theFIGS. 3 and 4which in this example is a valve which comprises a closing ring which is equipped with holes in which case the closing ring is being controlled by rotating it between two fixed rings23,24which are attached to the body of the hammering device16. In the fixed rings23,24the holes are divided to have the same distance from each other as in the closing ring. The valve2is open when the closing ring is being rotated in such a way that the holes are at the same location. The valve2is closed by rotating the closing ring in such a way that the unbroken necks of the closing ring are at the location of the holes of the fixed rings.

TheFIG. 4shows the upper, fixed ring24which has holes (circles) which are shown with a unitary line. The holes of the closing ring—every second hole—are shown with dashed lines. The valve2is closed in the section view picture4. The closing ring is being rotated with the help of a double action hydraulic cylinder25which is located in the part22which cylinder is adjusted to rotate the closing ring between the rings23,24with the help of a arm28. The sliding surfaces of all the rings are polished and are located against each other with an accurate fit in which case the leakages have been minimized. The opening of the valve can be performed quickly and the pressure shocks, too, are limited only at the surroundings of the valve.

FIG. 5shows a device which is modified from the hammering device of theFIG. 2and hits in one direction. The chambers K1and K2function as gas spaces. The valves10and11are not needed.

A percussion hammer which hits downwards is shown in theFIG. 6to which percussion hammer a valve2according to the invention has been adapted. There are essentially less flow losses in the holes of the valve2during the hammering movement of the hammering piston3than in the known structures in which the liquid must be removed fast out of the cylinder through a piping and even the resistance of the valve is present. The hammering piston3hits directly to the tool27.