How do investors help a company?

I am interested in buying a percentage of the inventory from my family's business, in return for the same percentage in company profits at the end of the year. This business has a $160,000 inventory and makes $219,000 in profit (37% increase) per year. If this business has a $160,000 inventory and I buy $78,400 (49%), how could the company use my money to benefit from my investment?