Non chattering pressure relief valve

1. A pressure relief valve comprising:

a valve body having an inlet and an outlet and defining a first fluid path fluidly connecting the inlet and the outlet of the valve, the valve body defining a valve seat;

a valve member axially moveable between a first position and a second position for sealing against the valve seat, the valve member configured to close the first fluid path in the first position and thereby restrict flow between the inlet and the outlet, the valve member configured to open the fluid path in the second position and thereby allow flow between the inlet and the outlet;

a biasing element configured to bias the valve member in the first position; and

a frictional resistance means for preventing the pressure relief valve from oscillating, the frictional resistance means being resiliently biased laterally against an axially extending surface of the valve member to provide frictional resistance to movement of the valve member and thereby cause hysteresis in axial movement of the valve member between the first position and the second position, wherein the frictional resistance means has an inner diameter that is greater than a diameter of the valve seat.

2. The pressure relief valve of claim 1 , wherein the valve member is a poppet.

3. The pressure relief valve of claim 2 , further comprising an annular spacer in line with the first fluid path and configured to remain fixed relative to the body; and

a poppet chamber in the spacer.

4. The pressure relief valve of claim 3 , wherein a venting hole in the spacer fluidly connects the poppet chamber to the first fluid path.

5. The pressure relief valve of claim 1 , wherein the frictional resistance means is an O-ring.

6. The pressure relief valve of claim 1 , wherein the axially extending surface of the valve member has a diameter that is no less than a radially outermost diameter of the valve member.

7. A pressure relief valve comprising:

a housing surrounding a first fluid path that fluidly connects an upstream flow passage and a downstream flow passage of the housing, the upstream flow passage being axially aligned with the downstream flow passage;

an annular spacer in line with the first fluid path and configured to remain fixed relative to the housing;

a poppet chamber in the spacer;

a poppet configured to slide axially within the poppet chamber and having a head to seal against a valve seat in the housing, wherein in a first closed position, the poppet prevents fluid flow through the first fluid path, and in a second, open position, the poppet allows fluid flow through the first fluid path;

a friction element configured to press laterally against an axially extending surface of the poppet and cause hysteresis in axial movement of the poppet between the first position and the second position, wherein the friction element has an inner diameter that is greater than a diameter of the valve seat; and

a biasing element configured to bias the poppet outwardly from the chamber of the spacer into the first closed position,

wherein a portion of the first fluid path is between the housing and the spacer.

8. The pressure relief valve of claim 7 , wherein a venting hole in the spacer fluidly connects the poppet chamber to the first fluid path.

9. The pressure relief valve of claim 7 , wherein the friction element is an O-ring.