I would like some help in regards to patent number US 20020187719 A1/ US6666740. I would like to manufacture something similar in Brazil, but don't want to infringe any patents. That is why I'd like to know if this patent is valid internationally or only in the US and if I can manufacture something similar without breaking any rules.
You have referred to a US patent (and application). This is only effective in the US, and therefore could not apply in other countries.
In addition, by searching for the inventor's name at INPI, it appears that no related Brazilian patent exists.
It therefore appears at first blush that this patent (or any equivalents) would not prevent you manufacturing this product in Brazil.
However, other relevant patents may exist in Brazil which could affect you. You would need to perform (or engage an attorney to perform) a freedom-to-operate search to establish this.