Tricky how to look at this. Companies make money. Companies just as easily lose money, and the majority of products introduced into the market fail to make money. The investors and owners of the company get to keep the profits, and they have to put in the money when things go the other way.
Just because you worked on a project does not mean you deserve part of the outcome. Conversely, if your work was not appreciated by the consumer, you do not have to refund your design fee. If you charge 3K and the company loses 400K, then also the rate does not reflect the outcome.
If your talents are unique enough, and your sales skills persuasive enough, and your comfort level in the partner high enough, you can choose negotiate to share the risk and the reward. You can also choose to be paid for your contribution in whole up front and let the company keep the risks and rewards. You have to accept the outcome that you negotiated from the beginning. Be comfortable with someone else making money from the success of your designs, it is building your value as well.
Charge too much and they go to someone else, pure and simple. Ask for a royalty when an equally competitive designer is not asking for it, and the will choose him. Most companies will not pay a royalty, too complicated, they want the costs in up front, and design and industrialization are one of the costs.