Vehicle suspension system with one or more frequency dependent roll stiffness valves

A suspension system, comprising:

• a front left damper including a damper housing, a first compression chamber, and a first rebound chamber;
• a front right damper including a damper housing, a second compression chamber, and a second rebound chamber;
• a back left damper including a damper housing, a third compression chamber, and a third rebound chamber;
• a back right damper including a damper housing, a fourth compression chamber, and a fourth rebound chamber;
• a first hydraulic circuit including a front hydraulic line, a rear hydraulic line, and a first longitudinal hydraulic line that extends between and fluidly connects said front and rear hydraulic lines of said first hydraulic circuit;
• said front hydraulic line of said first hydraulic circuit extending between and fluidly connecting said first longitudinal hydraulic line and said second rebound chamber of said front right damper;
• said rear hydraulic line of said first hydraulic circuit extending between and fluidly connecting said first longitudinal hydraulic line and said fourth rebound chamber of said back right damper;
• said first longitudinal hydraulic line extending between and fluidly connecting said first compression chamber of said front left damper and said third compression chamber of said back left damper;
• a second hydraulic circuit including a front hydraulic line, a rear hydraulic line, and a second longitudinal hydraulic line that extends between and fluidly connects said front and rear hydraulic lines of said second hydraulic circuit;
• said front hydraulic line of said second hydraulic circuit extending between and fluidly connecting said second longitudinal hydraulic line and said first rebound chamber of said front left damper;
• said rear hydraulic line of said second hydraulic circuit extending between and fluidly connecting said second longitudinal hydraulic line and said third rebound chamber of said back left damper;
• said second longitudinal hydraulic line extending between and fluidly connecting said second compression chamber of said front right damper and said fourth compression chamber of said back right damper;
• and
• at least one frequency dependent valve disposed on or in said damper housing of each of said dampers and that is arranged to control fluid flow between said first hydraulic circuit and said second hydraulic circuit,
• wherein each frequency dependent valve has a closed position where said frequency dependent valve blocks fluid flow between said first and second hydraulic circuits and an open position where said frequency dependent valve permits fluid flow between said first and second hydraulic circuits,
• wherein said first and third compression chambers of said front left and back left dampers are fluidly coupled to said second and fourth rebound chambers of said front right and back right dampers by said first hydraulic circuit and said second and fourth compression chambers of said front right and back right dampers are fluidly coupled to said first and third rebound chambers of said front left and back left dampers by said second hydraulic circuit such that said suspension system provides passive roll resistance when said frequency dependent valves are closed and wherein said frequency dependent valves are configured to switch from said closed position to said open position to hydraulicly decouple said dampers when fluid pressure increases within said first hydraulic circuit or said second hydraulic circuit rise above a pre-determined threshold frequency.