This can be achieved in tortoise SVN itself. Right click on the branch(folder) from where you want to create the patch >> Show Log
>> Select All the revisions for which you need to create the patch >> Right Click and select Compare revisions
>> This will show the changed files >> Select all the files >> Right click and select Export Revision To
>> Give any path in your machine >> The files will get exported in the respective folder structure.
Alternately you can achieve this via scripting. Refer the following link for that:
http://www.electrictoolbox.com/subversion-export-changed-files-cli