If you wish to use the Tier 1 Investor visa as a route to settling in the UK (‘indefinite leave to remain’), you must not spend more than 180 days outside the UK during any 12-month period.
When you apply for settlement, you will be expected to provide information about times of absence from the UK while on the visa, including the reasons for these absences. Whatever your reasons are, the absences will still count towards the maximum 180 days allowed, even if you were absent for work reasons or serious and compelling reasons.
The only exception to this rule would be if you spent time away from the UK helping with a national or international humanitarian or environmental crisis. If this is the case for you, evidence can be provided for this being the purpose of your absence.