Pressure control valve

A pressure control valve comprising:

• a valve housing extending along an axis (A);
• an inlet configured to be connected to a high pressure fluid supply;
• an outlet;
• a valve seat;
• a valve piston mounted within the valve housing arranged to move axially within the valve housing relative to the valve seat;
• a compression spring located between the valve piston and an end of the valve housing to axially bias the valve piston relative to the valve seat;
• and
• a check valve located within the valve piston;
• wherein the check valve comprises:
• a check valve ball biased relative to the valve piston by a check valve spring whose stiffness determines a pressure differential controlling operating of the pressure control valve;
• wherein the valve piston has a first end proximate the valve seat and a second, opposite end adjacent the compression spring;
• and
• wherein the second end is configured to receive the check valve
• wherein the valve piston has a first end proximate the valve seat and a second, opposite end adjacent the compression spring;
• and
• wherein the second end is configured to receive the check valve;
• the check valve further comprising:
• a flange intermediate the first end and the second end extending radially outwards towards the valve housing;
• wherein:
• a first fluid chamber is formed in the valve housing between the flange and the second end of the valve piston;
• a second fluid chamber is formed between the second end of the valve piston and the end of the valve housing;
• a third fluid chamber is formed between the flange and the first end of the valve piston;
• and
• the first fluid chamber is provided to be in fluid communication with a fluid supply for controlling operation of the valve and the third fluid chamber provides fluid to a control valve outlet;
• wherein the second end of the valve piston has an outer diameter sized to form a sealing engagement with the valve housing, the flange has a radial dimension that is less than that of the second end of the valve piston but greater than the first end of the valve piston;
• wherein the pressure control valve configured such that:
• high pressure fluid flows from the inlet into the first fluid chamber, and acts against the force of the check valve spring to open the check valve to permit fluid from the first fluid chamber to flow through the check valve to the second fluid chamber and further into the third fluid chamber;
• and
• as fluid continues to flow from the inlet, the pressure of the fluid in the third fluid chamber increases until it overcomes the compression spring and compresses it to move the piston into the second fluid chamber until the flange abuts the valve housing to close the flow path from the second fluid chamber to the third fluid chamber whereupon the fluid in the third fluid chamber flows out through the outlet such that the pressure acting from the third fluid chamber on the compression spring is reduced and the compression spring expands to move the piston to re-open the flow path from the second fluid chamber to the third fluid chamber.