Gas sensor with a pump cell
View Patent ↗A gas sensor includes an electrochemical cell having a solid electrolyte layer disposed between a sensing electrode and a reference electrode; a heater disposed in thermal communication with the electrochemical cell, the heater having a positive heater lead and a negative heater lead; a reference gas channel; a reference chamber in fluid communication with the reference electrode; a pump cell having a first pump cell electrode in fluid communication with the reference gas channel and also having a second pump cell electrode in fluid communication with the reference chamber. The first pump cell electrode has a pump cell first lead which forms a first electrical junction with either the positive heater lead and the negative heater lead and the second pump cell electrode has a pump cell second lead which forms a second electrical junction with the same heater lead as the pump cell first lead.
1. A gas sensor comprising:
an electrochemical cell having a first solid electrolyte layer disposed between a sensing electrode and a reference electrode;
a heater disposed in thermal communication with said electrochemical cell, said heater having a positive heater lead and a negative heater lead;
a reference gas channel;
a reference chamber in fluid communication with said reference electrode; and
a pump cell having a first pump cell electrode in fluid communication with said reference gas channel and also having a second pump cell electrode in fluid communication with said reference chamber such that application of a voltage difference between said first pump cell electrode and said second pump cell electrode causes oxygen ions to be pumped from said reference gas channel to said reference chamber, wherein said first pump cell electrode has a pump cell first lead which forms a first electrical junction with one of said positive heater lead and said negative heater lead and wherein said second pump cell electrode has a pump cell second lead which forms a second electrical junction with said one of said positive heater lead and said negative heater lead.
2. The gas sensor as in claim 1 , further comprising:
a protective insulating layer on said first solid electrolyte layer, said protective insulating layer being electrically insulative; and
a second solid electrolyte layer on said protective insulating layer such that said protective insulating layer is between said first solid electrolyte layer and said second solid electrolyte layer;
wherein said first pump cell electrode and said second pump cell electrode are disposed on said second solid electrolyte layer such that said second solid electrolyte layer is between said first pump cell electrode and said protective insulating layer and such that said second solid electrolyte layer is between said second pump cell electrode and said protective insulating layer.
3. The gas sensor as in claim 1 further comprising a pressure bleed passage which provides fluid communication out of said reference chamber.
4. The gas sensor as in claim 1 further comprising:
a first protective insulating layer such that said first protective insulating layer is located between said heater and said electrochemical cell;
and a pressure bleed passage which provides fluid communication out of said reference chamber.
5. The gas sensor as in claim 4 wherein said pressure bleed passage provides fluid communication from said reference chamber to said reference gas channel.
6. The gas sensor as in claim 4 wherein said pump cell first lead passes through said first protective insulating layer and said pump cell second lead passes through said first protective insulating layer.
7. The gas sensor as in claim 4 further comprising:
a second protective insulating layer on said first solid electrolyte layer such that said second protective insulating layer is between said first protective insulating layer and said first solid electrolyte layer, said second protective insulating layer being electrically insulative; and
a second solid electrolyte layer on said second protective insulating layer such that said second protective insulating layer is between said first solid electrolyte layer and said second solid electrolyte layer;
wherein said first pump cell electrode and said second pump cell electrode are disposed on said second solid electrolyte layer such that said second solid electrolyte layer is between said first pump cell electrode and said second protective insulating layer and such that said second solid electrolyte layer is between said second pump cell electrode and said second protective insulating layer.
8. The gas sensor as in claim 1 , further comprising a second solid electrolyte layer, wherein said first pump cell electrode and said second pump cell electrode are disposed on said second solid electrolyte layer such that said second solid electrolyte layer is between said first pump cell electrode and said first solid electrolyte layer and such that said second solid electrolyte layer is between said second pump cell electrode and said first solid electrolyte layer.
9. The gas sensor as in claim 8 further comprising a protective insulating layer on said first solid electrolyte layer, wherein said protective insulating layer is electrically insulative and wherein said protective insulating layer is between said first solid electrolyte layer and said second solid electrolyte layer.