US 8,939,227 B2 · Pressure protection valve for hydraulic tool

Abstract

A pressure protection valve is provided which provides a fluid short circuit between a fluid pressure inlet of a hydraulic tool such as a hydraulic hammer and a low pressure region when the pressure at the fluid pressure inlet exceeds a first trigger pressure equal to a predetermined permissible pressure. This prevents damage to the hydraulic tool which can arise through operation at excessive fluid flow or pressure from hydraulic fluid supplied by a carrier vehicle. The pressure protection valve may maintain fluid communication between the fluid pressure inlet and the low pressure region until the pressure at the fluid pressure inlet reduces to a pressure below a predetermined second trigger pressure which is less than the first trigger pressure, to prevent further operation of the tool until the flow of fluid to the fluid pressure inlet has been stopped by an operator.

Claims15

Dependent claims

A hydraulic hammer comprising:

a percussion piston arranged for reciprocating movement within a cylinder housing by controlled fluid pressure;
a work tool operable by said percussion piston;
a piston control valve for controlling the reciprocating movement of said percussion piston in fluid communication with a fluid pressure inlet line adapted to provide pressurised fluid;
and
a pressure protection valve arranged to:
provide fluid communication between the fluid pressure inlet line and a low pressure region when the pressure at the fluid pressure inlet line exceeds a predetermined first trigger pressure;
and
maintain fluid communication between the fluid pressure inlet line and the low pressure region until the pressure at the fluid pressure inlet line reduces to a pressure below a predetermined second trigger pressure which is less than the first trigger pressure.

5 more elements

A pressure protection valve for a hydraulic tool having a fluid pressure inlet, the pressure protection valve being adapted to provide a fluid short circuit between the fluid pressure inlet and a low pressure region when the pressure at the fluid pressure inlet exceeds a predetermined first trigger pressure,

wherein the pressure protection valve is arranged to:
provide fluid communication between the fluid pressure inlet and a low pressure region when the pressure at the fluid pressure inlet exceeds a predetermined first trigger pressure;
and
maintain fluid communication between the fluid pressure inlet and the low pressure region until the pressure at the fluid pressure inlet reduces to a pressure below a predetermined second trigger pressure which is less than the first trigger pressure.

1 more element

A method of disabling a hydraulic tool when fluid pressure in a fluid pressure inlet line which supplies pressurised fluid to the tool reaches or exceeds a predetermined working pressure, comprising:

providing a pressure protection valve arranged between the fluid pressure inlet line and a low pressure region;
using the pressure protection valve to monitor the fluid pressure in the fluid pressure inlet line;
opening the pressure protection valve to provide fluid communication between the fluid pressure inlet line and the low pressure region when the fluid pressure in the fluid pressure inlet line exceeds a predetermined first trigger pressure equal to the predetermined working pressure;
maintaining the pressure protection valve open to provide fluid communication between the fluid pressure inlet line and the low pressure region when the fluid pressure in the fluid pressure inlet line is reduced to a pressure below the predetermined first trigger pressure and above a predetermined second trigger pressure;
and
closing the pressure protection valve to prevent fluid communication between the fluid pressure inlet line and the low pressure region when the fluid pressure in the fluid pressure inlet line is reduced to a pressure below the predetermined second trigger pressure.

3 more elements

Dependencies are inferred from the claim text.

Pressure protection valve for hydraulic tool

Life of this patent

Pressure protection valve for hydraulic tool

Life of this patent

Abstract

Claims15