Patent ID: 9523425
Filing Date: 2016-12-20
CPC Classification: B60Y,F16H,Y10T

Claim Text:
1. A hydraulic control unit, comprising: a valve comprising a piston integrated with a valve element, a cylinder holding the piston while allowing to reciprocate axially, a positive pressure chamber which is formed on one side of the piston and to which hydraulic pressure to open the valve is applied, a back pressure chamber which is formed on the other side of the piston and to which the hydraulic pressure to close the valve is applied, and a connection passage having a function to differentiate hydraulic pressures in the positive pressure chamber and the back pressure chamber; a pilot valve that selectively connects the back pressure chamber with a site where the pressure is lower than that of the back pressure chamber; a low pressure section to which the hydraulic pressure lower than that applied to positive pressure chamber is applied; and a controller configured to deliver hydraulic fluid from the low pressure section to the back pressure chamber through a bypass passage if an opening motion of the valve is slower than a predetermined reference value, by opening the pilot valve to allow the hydraulic fluid to be drained from the back pressure chamber to the site where the pressure is lower than that of the back pressure chamber.