Diagnosis concept for valve controlled coolant bypass paths
AssigneeGM Global Technology Operations LLC
InventorOliver Maier
Life of this patent
Estimating the term…
Abstract
A system and method for determining whether a shut-off valve in a cabin heating by-pass line of a thermal sub-system associated with an engine has failed that uses the pump current for a pump that pumps the cooling fluid through the by-pass line. The method includes setting a predetermined constant speed of the pump and then providing a valve command that opens the by-pass valve. The method then determines if the pump current has increased or remained substantially the same when the by-pass valve is commanded open, and determines that the by-pass valve has not opened if the pump current remains substantially constant when the by-pass valve is commanded open.
Claims18
A method for determining whether a by-pass valve has failed, said method comprising:
- providing a power source;
- pumping a cooling fluid through the power source and a coolant loop external to the power source using an electrical pump;
- providing a by-pass line in the coolant loop that includes the by-pass valve;
- controlling the position of the by-pass valve to allow the cooling fluid to flow through the by-pass line or not flow through the by-pass line;
- setting a predetermined constant speed of the pump;
- providing a valve command that opens the by-pass valve after the pump speed has been set;
- determining if a pump current has increased or remained substantially constant after the by-pass valve is commanded open;
- and
- determining that the by-pass valve has not opened if the pump current remains substantially constant when the by-pass valve is commanded open.
A method for determining whether a valve that selectively provides a cooling fluid flow to an electric cabin heater in a vehicle has failed, said method comprising:
- providing a valve command that opens the valve;
- and
- determining that the valve has not opened in response to the valve command if a pump current for a pump that pumps the cooling fluid through the valve remains substantially constant when the valve is commanded open.
A method for determining whether a by-pass valve in a by-pass line has failed, said by-pass line being part of a coolant loop that directs a cooling fluid through a fuel cell stack and a line external to the fuel cell stack that is pumped by an electrical pump, said by-pass line directing the cooling fluid to a cabin heater when the by-pass valve is open, said method comprising:
- setting a predetermined constant speed of the pump;
- storing a pump current value after the pump speed has been set;
- providing a valve command that opens the by-pass valve after the pump speed has been set and the pump current value has been stored;
- determining if the pump current has increased or remained substantially constant after the by-pass valve is commanded open by comparing the pump current to the stored pump current value;
- and
- determining that the by-pass valve has not opened if the pump current remains substantially constant when the by-pass valve is commanded open.
Dependencies are inferred from the claim text.