Automatic water amount regulating flow sensor and constant temperature gas water heater

The utility model discloses an automatic water amount regulating flow sensor and a constant temperature gas water heater. The automatic water amount regulating flow sensor is composed of an outer valve body, a water flow rotor arranged in the outer valve body and a Hall element arranged on the side wall of the outer valve body. A vertical tubular inner valve body, a T-shaped valve element located in the inner valve body and a spring arranged on the valve element in a sleeving mode are additionally arranged in a water outlet in the outer valve body. The spring is made of memory alloy. The upper end and the lower end of the inner valve body are respectively fixed to supporting plates arranged on the inner wall of the outer valve body respectively. The upper end of the inner valve body penetrates through the upper supporting plate and arranged at an upper end opening in the inner valve body in a sealed and blocked mode through the top of the valve element. The lower supporting plate is provided with a water inlet hole communicated with the inner valve body. The lower end of the spring is fixed to the lower supporting plate. The upper end of the spring is fixed to the top of the valve element and stretches out or draws back along with the temperature of input water to drive the valve element to lift, so that the distance between the top of the valve element and the upper end opening of the inner valve body is made to be changed to adjust the water inflow. The spring can stretch out or draw back according to the temperature of the input water so as to adjust the water inflow automatically, and the automatic water amount regulating flow sensor is sensitive in reaction, so that the water heater is better in constant temperature effect and safe and reliable.