Design of a Quieter Flow Restrictor for Automotive Heater Circuit Applications
Publication Date: 2008-Feb-04
The IP.com Prior Art Database
Quieter Flow Restrictor
Use of variable flow restrictors is a common practice in automotive heater circuits. These flow restrictors allow optimum amount of engine coolant flow to the heater core that is packaged in the HVAC system under the instrument panel. Under the engine idling conditions, it allows certain amount of coolant flow. However, at higher engine RPMs, due to higher speeds and increased temperature, the restrictor gets constricted resulting in somewhat reduced flow to the heater core. This ensures long term durability of the heater cores, especially if they are not designed for higher coolant flows. This variable coolant flow control is achieved by a relatively free floating rubber puck with and orifice. Under certain engine operating conditions, flow temperature/pressure and upstream/downstream hose lengths - a resonance of this rubber puck is induced which readily gets transmitted to the heater core and sounds like a pure tone or whistle. This tone when excited is quiet audible inside/outside the vehicle.
This disclosure is to suppress this tone. The free floating rubber puck that serves as the restrictor (orifice), is modified as described in the new approach, to eliminate the induced vibration w/o sacrificing its flow variability feature for different operating conditions. The proposed invention with extended ribs on the rubber puck allows it stay constrained in the restric...