Device which I bought is design to work in 100 mm pipe. I modified this device to be able to work in 300 mm pipe. I have made meager modifications to it. I added wheels base to increase it size and for easier travel in the pipe, I have installed more powerful motors to suit work in bigger diameter. So now my device perform as it's bigger and more expensive model. I have personally design all of the modifications and I'am not intend to sell it or manufactured. Is only for use in my company. On my website I have published pictures of the modified device which do not contain any trademarks of the manufacturer. The appearance of my device is visibly different then original one. Should I be worried or I didn't broke any law modifying it? I would appreciate any help in this matter as this project consume a lot of my work and money.
The act that the manufacturer offered something to sell would imply that you are free to use it. It would be strange for a manufacturer to sue you for using the product, wouldn't it? So you are safe.
Let's suppose that you developed and "manufactured" the item yourself, the patent owner would have no claim against you. The purpose of patent law to to encourage inventors to teach the public about their invention instead of keeping them as trade secret. In fact, a patent could be invalidated if it's found the inventor withheld critical information required to duplicate the invention. Since the purpose of the law is to encourage more innovation, the law should not prohibit you from using others invention in your development effort.
The manufacturer likely has no claim against your posting a photo on the Web. The only possible way they can raise an objection is if the photo implied that you manufactured the product and therefore violated their trademark. But you probably don't need to worry about it. At least in the U.S. law, if the manufacturer threatened to sue you without offering remedy, for example, a chance for you to put up a trademark notice, you would then have ground to sue them first and put them in unfavorable position.
The manufacturer likely won't sue you even if they suspect you want to commercialize the product. First, it would be extremely hard for them to prove that any damage has occurred, and litigation is way too expensive to be justifiable.
The only time you should worry is if the manufacturer has grudge against you and want to raise frivolous lawsuits at any cost.
Udated answer: I missed the part about that you bought it. That is like a contract that you may use the device in whichever way you like. Our could be more an issue with copyright, but I doubt this. (Meaning: are you allowed to change the appearance of the device?) For the test see the answer of daniel.