System and method for operating a lubrication system with mechanical control

A method of operating a lubrication system, the method comprising:

• directing a lubricant from an outlet of a heat exchanger to a stator lubrication circuit;
• directing the lubricant from the outlet of the heat exchanger to a gearbox lubrication circuit;
• selectively directing the lubricant to a rotor lubrication circuit, wherein the rotor lubrication circuit includes a rotor circuit mechanical valve upstream of a rotor and is configured to block a flow of the lubricant to the rotor when a pressure of the lubricant immediately upstream of the rotor circuit mechanical valve is less than a cracking pressure of the rotor circuit mechanical valve and the rotor circuit mechanical valve is configured open when the pressure of the lubricant immediately upstream of the rotor circuit mechanical valve is greater than the cracking pressure of the rotor circuit mechanical valve;
• and
• bypassing lubricant around the heat exchanger with a heat exchanger bypass passage forming a connection to the rotor lubrication circuit, wherein the heat exchanger bypass passage includes a bypass mechanical valve located upstream of the rotor circuit mechanical valve and the bypass mechanical valve includes a cracking pressure to move from an open position to a closed position that is greater than the cracking pressure of the rotor circuit mechanical valve.

A vehicle comprising:

• a passenger compartment;
• a plurality of wheels supporting the passenger compartment;
• a traction motor having a rotor and a stator with the rotor configured to drive at least one of the plurality of wheels through a gearbox;
• and
• a lubrication system including:
• a heat exchanger having an inlet and an outlet;
• a gearbox lubrication circuit fluidly connecting a gearbox between the inlet and the outlet of the heat exchanger;
• a stator lubrication circuit fluidly connecting a stator between the inlet and the outlet of the heat exchanger;
• a rotor lubrication circuit fluidly connecting a rotor between the inlet and the outlet of the heat exchanger, wherein the rotor lubrication circuit includes a rotor circuit mechanical valve located upstream of an inlet to the rotor and downstream of the outlet of the heat exchanger and the rotor circuit mechanical valve is configured to move from a closed position to an open position when a pressure immediately upstream of the rotor circuit mechanical valve reaches a rotor circuit mechanical valve cracking pressure;
• and
• a heat exchanger bypass passage configured to bypass the inlet to the heat exchanger and connect with the rotor lubrication circuit downstream of the outlet of the heat exchanger, wherein the heat exchanger bypass passage includes a bypass mechanical valve upstream of the rotor circuit mechanical valve and the bypass mechanical valve includes a cracking pressure to move from an open position to a closed position that is greater than the cracking pressure of the rotor circuit mechanical valve.