How to learn Design Patterns

Jeremy D. Miller talks in his blog about how to learn and apply Design Patterns.

https://codebetter.com/blogs/jeremy.miller/archive/2005/09/01/131509.aspx

I completely agree with his ideas, however I've been in frustrating situations when you come to an existing project, and you want to apply patterns, If the product is working ¿how do you convince to Project Managers how important is a well-design to a long term solution?

In my experience, PMs only cares about milestones, calendars, and maybe features (they don't care how well designed it is), or better if the customer feels like if the feature is completed, without any quality measurement.

I love design patterns, and I would like to improve my knowledge about them to be a better developer. I think every good programmer agree with me.

But what we need to learn is "how to teach" the importance of design patterns to Project Managers.