Patent ID: 8500035
Filing Date: 2013-08-06
Classification: G05D

Abstract:
1. A thermostatic mixing valve comprising: a housing having a hot water inlet, a cold water inlet, and a mixed water outlet; a hot water valve seat positioned in the housing adjacent the hot water inlet; a cold water valve seat positioned in the housing adjacent the cold water inlet; a mixing chamber defined in the housing between the cold water inlet and the hot water inlet; a plunger received in the mixing chamber and adapted to be moved along a longitudinal axis of the housing between the cold water valve seat and the hot water valve seat, wherein the plunger and the hot water valve seat define a hot water valve opening controlling flow from the hot water inlet to the mixing chamber, and the plunger and the cold water valve seat define a cold water valve opening controlling flow from the cold water inlet to the mixing chamber; a sensing chamber defined in the housing and connected to the mixed water outlet; an insert positioned in the housing between the mixing chamber and the sensing chamber and defining at least one mixed fluid passageway extending between the mixing chamber and the sensing chamber; a thermal motor located at least partially within the sensing chamber and extending through the insert to the plunger, whereby expansion of the thermal motor causes movement of the plunger towards the hot water valve seat; a plunger return spring biasing the plunger toward the cold water valve seat; a funnel extending from a first end of the insert into the mixing chamber and including a distal end forming the cold water valve seat; at least one cold water bypass passageway defined between an outwardly facing surface of the funnel and an inwardly facing surface of the insert for connecting the cold water inlet to the sensing chamber, the cold water bypass passageway positioned such that cold water can bypass the cold water valve opening and flow from the cold water inlet to the sensing chamber; and a check valve adapted to normally close the cold water bypass passageway and only allow flow through the bypass passageway and into the sensing chamber upon fluid pressure within the sensing chamber dropping below pressure in the cold water inlet, wherein the insert includes a tubular outer wall, a tubular inner wall, and a tubular intermediate wall, wherein the walls of the insert are coaxial with the longitudinal axis of the housing, the mixing water passageway is defined between the inner wall and the intermediate wall, and the cold water bypass passageway is disposed between the intermediate wall and the outer wall.