Patent fee is the result of negotiation between the two parties, and the key lies in the economic benefits contained in the patent. When both sides agree, it is easy to reach an agreement, otherwise it is difficult. For the above problems, does the fixed structure save materials compared with the existing methods? Or did you save the heating wire? Power consumption? How much profit does the manufacturer have from the value saved? How much do you have left after you share the patent fee? You can make an estimate of this kind of problem.
I didn't look up your patent, only answered the question.