Pressure relief valve

A pressure relief valve includes a housing, a poppet, and a spring. The housing includes an internal bore defined along a longitudinal axis of the housing and extending from an upper portion to a lower portion. A ledge or seat is defined within the bore. At least one lower portion hole is defined from an outer surface of the lower portion and into the bore. At least one upper portion hole is defined from an outer surface of the upper portion and into the bore. The poppet is slidably engaged within the internal bore. The poppet includes a head, a shaft, and an internal channel that runs longitudinally through the entire poppet. The head includes a shoulder. The spring is disposed within the bore at the upper portion of the housing and biases the poppet downwards so that the shoulder abuts the ledge or seat.

BACKGROUND OF THE INVENTION

The present invention relates to a pressure relief valve and, more particularly, to an improved direct acting pressure relief valve having improved reaction times.

A relief valve or pressure relief valve (PRV) is a type of safety valve used to control or limit the pressure in a system; pressure might otherwise build up and create a process upset, instrument or equipment failure, or catastrophic, uncontrolled release of pressure. The pressure is relieved by allowing the pressurized fluid to flow through an auxiliary passage to the system's reservoir, commonly referred to as “tank”.

Direct acting pressure relief valves require relatively large poppets and heavy springs to counter the pressure in the hydraulic system. Both the large poppet and heavy spring have the effect of slowing the operation of the valve. Therefore, the reaction time of direct operated pressure relief cartridge valves in hydraulic systems are relatively slow and may not prevent mechanical failures. Pilot operated pressure relief valves have a faster response time but have complicated designs and many more parts than direct acting relief valves. Hydraulic system designers must use the costlier pilot operated valves if response time is critical.

As can be seen, there is a need for an improved direct acting pressure relief valve having quicker reaction times.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a pressure relief valve comprises: a housing comprising an upper portion, a lower portion, and an internal bore defined along a longitudinal axis of the housing and extending from the upper portion to the lower portion, wherein a ledge or seat is defined within the bore in between the upper portion and the lower portion, at least one lower portion hole is defined from an outer surface of the lower portion and into the bore and at least one upper portion hole is defined from an outer surface of the upper portion and into the bore; a poppet slidably engaged within the internal bore, the poppet comprising a head and a shaft, wherein the head comprises a shoulder; and a spring disposed within the bore at the upper portion of the housing and biasing the poppet downwards so that the shoulder abuts the ledge, wherein a threshold pressure exerted against the shoulder through the at least one lower portion hole urges the poppet upwards against the bias of the spring so that pressure is released through the at least one upper portion hole.

DETAILED DESCRIPTION OF THE INVENTION

The present invention includes a direct operated hydraulic pressure relief cartridge valve with counter-balanced poppet. The present invention significantly reduces the reaction time to relieve spikes in pressure in hydraulic systems. The present invention may include a significant reduction of weight of the poppet and spring force to a point where the reaction is comparable to pilot operated valve poppet and spring.

Referring toFIGS. 1 through 7, the present invention is a modified pressure relief valve. The pressure relief valve includes a housing10, a poppet22, and a spring38. The housing10includes an upper portion, a lower portion, and an internal bore11defined along a longitudinal axis of the housing10and extending from the upper portion to the lower portion. A ledge13or seat is defined within the bore11in between the upper portion and the lower portion. At least one lower portion hole12is defined from an outer surface of the lower portion and into the bore. At least one upper portion hole14is defined from an outer surface of the upper portion and into the bore11. The poppet22is slidably engaged within the internal bore11. The poppet22includes a head and a shaft. The head includes a shoulder15. The spring38is disposed within the bore11at the upper portion of the housing10and biases the poppet22downwards so that the shoulder15abuts the ledge13.

The shoulder15may include a male frusto-conical shape and the ledge13may include a female frusto-conical shape. The bore11of the present invention may define a cylinder shape and may include a larger diameter at the upper portion and a smaller diameter at the lower portion. The head of the poppet22may include a larger diameter than the bore11at the lower portion and the shaft may include a smaller diameter than the bore11at the lower portion. The shaft of the poppet22is disposed within the bore at the lower portion. Pressure is thereby exerted along an entire lower edge of the head, allowing the poppet22to raise at a faster pace. When a threshold pressure is exerted against the shoulder15through the at least one lower portion hole12, the poppet22is urged upwards against the bias of the spring38so that pressure is released through the at least one upper portion hole14.

In certain embodiments, the at least one upper portion hole14includes a plurality of upper portion holes14circumferentially disposed around the housing10. In certain embodiments, the at least one lower portion hole12is a plurality of lower portion holes12circumferentially disposed around the housing10. The holes12,14may be evenly spaced apart. Therefore, an even amount of pressure may be exerted against the shoulder15and released through the upper portion holes14. In certain embodiments, the poppet22includes a channel17defined along a longitudinal axis of the poppet22. The channel17terminates at a top opening at a top of the head and a bottom opening at a bottom of the shaft. Pressure on the opposite ends of the poppet22are equalized due to the channel17, thereby equalizing pressure between the upper portion of the bore11and a reservoir19at a distal end of the bore11.

In certain embodiments, a tension of the spring38is adjustable. In such embodiments, the present invention may include a cap26having bottom opening and a top opening. The bottom opening includes female threading30mechanically fastened to male threading16of the housing10. The top opening of the cap26includes female threading28. An adjustment screw40includes male threading mechanically engaged with the female threading28of the top opening. A jam nut42is mechanically engaged with the adjustment screw40and is disposed above the cap36. An adjustment seal32is disposed between the end of the adjustment screw40and the spring38. An end of the adjustment screw40may be mechanically fastened to female threads34of the adjustment seal32. Rotating the adjustment screw40within the top opening adjusts the tension of the spring38.

As mentioned above, the poppet22fits into the housing10. The fit creates a metal to metal seal which contains the hydraulic system pressure. The spring38provides the force that holds the poppet22in position. The cap26, adjustment seal32, adjustment screw40, and jam nut42set and hold the desired release pressure. The O-rings18prevent leakage across the various components.

The valve housing10screws into a standard hydraulic cartridge valve cavity46of a hydraulic system pipe44. The system fluid enters the valve through the holes12of the housing10. The hydraulic system pressure pushes on both the bottom of the shaft and the shoulder15of the poppet22. Pressure on the opposite ends of the poppet12is equalized by the channel17that runs lengthwise in the poppet12. There is a small differential in the area exposed to the pressure. The spring38seats the poppet12against the housing10which results in a metal to metal seal. When the hydraulic system pressure results in force that is greater than the force of the spring38, the metal to metal seal separates and hydraulic pressure is relieved to the system's reservoir48. When the hydraulic system pressure decreases, the spring38reseats the poppet12.