it is just classical mecanic to understand that we are crawling around the sun at different speed during the day
earth fly at 30km/sec around the sun
earth spin at 1040mph (464m/s) 
both same direction
the closest part of the surface to the sun going opposite to the revolution
the fartest part of the surface to the sun going same direction as revolution

you are moving the fastest from the sun at midnight 30km/s + 464m/s
you are moving the slowest from the sun at noon     30km/s - 464m/s
technically there is no noticable time dilatation at this speed variation