GB2071221A

GB2071221A - Hydraulic percussive machine

Info

Publication number: GB2071221A
Application number: GB8105647A
Authority: GB
Original assignee: Centrum Konstrukcyjno Technologiczne Maszyn Gorniczych Komag
Current assignee: Centrum Konstrukcyjno Technologiczne Maszyn Gorniczych Komag
Priority date: 1980-02-22
Filing date: 1981-02-23
Publication date: 1981-09-16
Also published as: DE3106410C2; DE3106410A1; SE8101160L; PL222226A1; PL129069B1

Abstract

A hydraulic percussive machine has a ram 9 connected to a pressure supply or exhaust by a valve 7, the pressure supply including an accumulator 3 having a liquid working chamber 5 separated from a compressed gas chamber 6 by a piston 4 of which the mass is similar to that of the ram 9. <IMAGE>

Description

SPECIFICATION Hydraulic percussive machine The invention relates to a hydraulic percussive machine.

Known percussive machines, such as hydraulic hammers, and drilling percussive devices are equipped with accumulators to secure rapid flow in of working fluid into the ram working chamber to cause the ram to move out rapidly. These accumulators comprise a chamber containing a compressible fluid separated by a membrane from a chamber under hydraulic pressure. The provision of a membrane accumulator enables a pressure increase in the ram working chamber in proportion to the mass and velocity of the accelerated fluid in the pipe between accumulator and the work chamber at the moment wherein the tool driven by the ram is prevented from moving for example by work being excavated.

There is also known from French Patent Specification No. 2068026, a hydraulic hammer consisting of a cylinder containing a piston connected to piston rod. The cylinder vo!ume is divided by the piston in two chambers; the one filled with liquid and the other with compressed gas, the piston rod being coupled with the ram set to control the ram strokes. The piston mass is much less than that of the ram set, so it does not influence the work liquid compression when the ram strikes excavated rock.

According to the invention, there is provided a hydraulic percussive machine, comprising a hydraulic ram and an accumulator having a hydraulic working chamber connected to the working chamber of the ram and a compressed gas chamber separated from the hydraulic working chamber by a piston having a mass similar to that of the ram. Preferably the piston is weighted by being filled with a metal of high specific gravity.

The heavy piston results in pressure increase inside the work chamber of the ram not only related to the mass and velocity of accelerated liquid, but also to the mass and velocity of the accumulator piston which separates the gas from the hydraulic fluid. As the hydraulic fluid usually being mineral oil, is alost incompressible, when the liquid confined between the accumulator piston and ram is suddenly stopped by excavating tool hitting rock, the inertia of the piston is added to that of the fluid to apply an impact force to the ram.

The invention will now be described further, by way of example, with reference to an embodiment illustrated schematically in the accompanying drawing.

Pump 1 feeds hydraulic fluid through check valve 2 into an accumulator 3, having a piston 4 dividing its volume into a first working chamber 5 filled with hydraulic fluid and a second sealed chamber 6 filled with a gas such as nitrogen. A control valve, 7 which is manually operable connects accumulator 3 to a working chamber 8 of a ram 9, the latter being accelerated by pressure to strike at the end of its stroke against a tool 10 in contact with rock 11 to be excavated.

Restriction of the ram stroke results in a hydraulic surge pressure in chamber 8. The hydraulic surge pressure is proportional to the mass and velocity of accumulator piston 4.

To achieve an adquate mass of piston 4, it is filled with heavy metal, for instance with lead.

1. Hydraulic percussive machine, comprising a hydraulic, and an accumulator ram having a hydraulic working chamber connected to the working chamber of the ram and a compressed gas chamber separated from the hydraulic working chamber by a piston having a mass similar to that of the ram.

2. A hydraulic percussive machine as claimed in Claim 1, wherein the piston is filled with metal of high specific gravity.

3. A hydraulic percussive machine constructed substantially as herein described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Hydraulic percussive machine The invention relates to a hydraulic percussive machine. Known percussive machines, such as hydraulic hammers, and drilling percussive devices are equipped with accumulators to secure rapid flow in of working fluid into the ram working chamber to cause the ram to move out rapidly. These accumulators comprise a chamber containing a compressible fluid separated by a membrane from a chamber under hydraulic pressure. The provision of a membrane accumulator enables a pressure increase in the ram working chamber in proportion to the mass and velocity of the accelerated fluid in the pipe between accumulator and the work chamber at the moment wherein the tool driven by the ram is prevented from moving for example by work being excavated. There is also known from French Patent Specification No. 2068026, a hydraulic hammer consisting of a cylinder containing a piston connected to piston rod. The cylinder vo!ume is divided by the piston in two chambers; the one filled with liquid and the other with compressed gas, the piston rod being coupled with the ram set to control the ram strokes. The piston mass is much less than that of the ram set, so it does not influence the work liquid compression when the ram strikes excavated rock. According to the invention, there is provided a hydraulic percussive machine, comprising a hydraulic ram and an accumulator having a hydraulic working chamber connected to the working chamber of the ram and a compressed gas chamber separated from the hydraulic working chamber by a piston having a mass similar to that of the ram. Preferably the piston is weighted by being filled with a metal of high specific gravity. The heavy piston results in pressure increase inside the work chamber of the ram not only related to the mass and velocity of accelerated liquid, but also to the mass and velocity of the accumulator piston which separates the gas from the hydraulic fluid. As the hydraulic fluid usually being mineral oil, is alost incompressible, when the liquid confined between the accumulator piston and ram is suddenly stopped by excavating tool hitting rock, the inertia of the piston is added to that of the fluid to apply an impact force to the ram. The invention will now be described further, by way of example, with reference to an embodiment illustrated schematically in the accompanying drawing. Pump 1 feeds hydraulic fluid through check valve 2 into an accumulator 3, having a piston 4 dividing its volume into a first working chamber 5 filled with hydraulic fluid and a second sealed chamber 6 filled with a gas such as nitrogen. A control valve, 7 which is manually operable connects accumulator 3 to a working chamber 8 of a ram 9, the latter being accelerated by pressure to strike at the end of its stroke against a tool 10 in contact with rock 11 to be excavated. Restriction of the ram stroke results in a hydraulic surge pressure in chamber 8. The hydraulic surge pressure is proportional to the mass and velocity of accumulator piston 4. To achieve an adquate mass of piston 4, it is filled with heavy metal, for instance with lead. CLAIMS