Auxiliary coolant pump with bypass

A thermal system for a vehicle, the thermal system comprising:

• a coolant circuit configured to thermally couple to a vehicle engine for cooling thereof;
• a main coolant pump configured to circulate coolant through the coolant circuit;
• a heat exchanger thermally coupled to the coolant circuit;
• and
• an auxiliary coolant pump having an impeller configured to circulate coolant through the coolant circuit, and a housing defining a coolant inlet, a coolant outlet, and an internal bypass passage fluidly coupled between the inlet and the outlet to bypass the impeller,
• wherein when the main coolant pump is on, the auxiliary coolant pump is selectively turned off such that coolant flows through the bypass passage to reduce or eliminate restriction of the coolant flow rate in the coolant circuit, and
• wherein when the main coolant pump is off, the auxiliary coolant pump is selectively turned on to continue to provide coolant flow to the heat exchanger.

A vehicle comprising:

• an engine;
• a passenger cabin heat exchanger configured to provide heating to a passenger cabin;
• a controller;
• and
• a thermal system configured to provide passenger cabin heating during an engine stop/start, the thermal system comprising:
• a coolant circuit thermally coupled to the engine and the passenger cabin heat exchanger, the coolant circuit including a first loop and a second loop;
• a main coolant pump configured to circulate coolant through the coolant circuit;
• and
• an auxiliary coolant pump configured to circulate coolant through the first loop and having a housing, an impeller, an internal bypass passage within the housing configured to bypass the impeller, and a one-way valve disposed within the internal bypass passage,
• wherein the auxiliary coolant pump and the passenger cabin heat exchanger are disposed on the first loop, and a radiator is disposed on the second loop,
• wherein coolant in the first loop passes through the engine, the auxiliary pump, and the passenger cabin heat exchanger before returning through the main coolant pump,
• wherein coolant in the second loop passes through the engine and the radiator before returning through the main coolant pump, and
• wherein the controller is configured to:
• selectively turn on the auxiliary coolant pump when the main coolant pump is turned off and the vehicle engine is stopped during a stop/start mode to continue to provide heating to the passenger cabin;
• and
• when the main coolant pump is on, selectively turn off the auxiliary coolant pump such that coolant flows through the internal bypass passage to reduce or eliminate restriction of the coolant flow rate in the thermal system.