Hydraulic cylinder assembly for automotive suspension system and actively controlled suspension system utilizing same

A hydraulic cylinder assembly for an automotive suspension system for absorbing relative movement between a vehicle body and a suspension member rotatably mounting a vehicular wheel, said hydraulic cylinder assembly comprising:

• a cylinder housing opposed defining an internal space filled with a working fluid and connected to said first member, said internal space connected to a fluid pressure source via a hydraulic circuit;
• a piston disposed within said internal space of said cylinder housing and dividing said internal space into first and second fluid chambers, said first fluid chamber in fluid communication with said hydraulic circuit, said piston connected to said second member via a piston rod extending from said cylinder housing, and said piston including a first fluid flow path for permitting a limited flow rate of fluid between said first and second fluid chambers;
• a pressure control value means, disposed within said hydraulic circuit, for controlling introduction and draining of pressurized fluid into and from said first fluid chamber in order or adjust damping characteristics;
• a pressure accumulating unit having a body connected to said cylinder housing, said body defining a space in communication with said second fluid chamber via a flow restricting fluid path;
• and
• a free piston assembly disposed within said space of said body for dividing said space into a third fluid chamber and a pneumatic chamber, said third fluid chamber in communication with said second fluid chamber via said flow restricting fluid path, said free piston assembly movable depending upon a pressure difference between said third fluid chamber and said pneumatic chamber, for receiving pressurized fluid in said third fluid chamber when the fluid pressure in said second fluid chamber is higher than that in said third fluid chamber, for accumulating pressure and supplying pressure to said second fluid chamber when the fluid pressure in said second fluid chamber is lower than that in said third fluid chamber.

An actively controlled suspension system for automotive suspension, said actively controlled suspension system comprising:

• a hydraulic cylinder assembly disposed between a vehicle body and a suspension member rotatably supporting a vehicular wheel, said hydraulic cylinder comprising
• a cylinder housing defining an internal space filled with a working fluid and connected to said first member, said internal space connected to a fluid pressure source via a hydraulic circuit;
• a piston disposed within said internal space of said cylinder housing and dividing said internal space into first and second fluid chambers, said first fluid chamber in fluid communication with said hydraulic circuit, said piston connected to said second member via a piston rod extending from said cylinder housing, and said piston including a first fluid flow path for permitting a limited flow rate of fluid between said first and second fluid chambers;
• a pressure accumulating unit having a body connected to said cylinder housing, said body defining a space in communication with said second fluid chamber via a flow restricting fluid path;
• and
• a free piston assembly disposed within said space of said body for dividing said space into a third fluid chamber and a pneumatic chamber, said third fluid chamber in communication with said second fluid chamber via said flow restricting fluid path, said free piston assembly movable depending upon a pressure difference between said third fluid chamber and said pneumatic chamber, for receiving pressurized fluid in said third fluid chamber when the fluid pressure in said second fluid chamber is higher than that in said third fluid chamber, for accumulating pressure and supplying pressure to said second fluid chamber when the fluid pressure in said second fluid chamber is lower than that in said third fluid chamber, and
• a hydraulic means, interposed within said hydraulic circuit and associated with said first chamber of said hydraulic cylinder, for adjusting fluid pressure in said first chamber to control attitude of a vehicle so as to suppress attitude changes of said vehicular body, said hydraulic means includes a pressure source and a pressure control valve which is electrically controlled to introduce pressurized working fluid into said first chamber and to drain working fluid from said first chamber depending upon vehicle driving conditions.

A hydraulic cylinder assembly for damping relative displacement of relatively movable first and second members, said hydraulic cylinder assembly comprising:

• a cylinder housing defining an internal space filled with a working fluid and connected to said first member, said internal space connected to a fluid pressure source via a hydraulic circuit;
• a piston disposed within said internal space of said cylinder housing and dividing said internal space into said first and second fluid chambers, said first fluid chamber in fluid communication with said hydraulic circuit, said piston connected to said second member via a piston rod extending from said cylinder housing, and said piston including a first fluid flow path for permitting a limited flow rate of fluid between said first and second fluid chambers and a second fluid flow path for permitting one-way fluid flow from said second fluid chamber to said first fluid chamber;
• a pressure control valve means, disposed within said hydraulic circuit, for controlling introduction and draining of pressurized fluid into and from said first fluid chamber in order to adjust damping characteristics;
• a pressure accumulating unit having a body connected to said cylinder housing, said body defining a space in communication with said second fluid chamber via a third flow restricting fluid path for permitting a limited flow rate of fluid between said second and third fluid chambers and a fourth fluid path permitting one-way fluid flow from said third fluid chamber to said second fluid chamber;
• and
• a free piston assembly disposed within said space of said body for dividing said space into a third fluid chamber and a pneumatic chamber, said third fluid chamber in communication with said second fluid chamber via said flow restricting fluid path, said free piston assembly movable depending upon a pressure difference between said third fluid chamber and said pneumatic chamber, for receiving pressurized fluid in said third fluid chamber when fluid pressure in said second fluid chamber is higher than that in said third fluid chamber, for accumulating pressure and supplying pressure to said second fluid chamber when fluid pressure in said second fluid chamber is lower than that in said third fluid chamber.

A hydraulic cylinder assembly for an automotive suspension system for absorbing relative movement between a vehicle body and a suspension member rotatably mounting a vehicular wheel, said hydraulic cylinder assembly, comprising:

• a cylinder housing defining an internal space filled with a working fluid and connected to a first member, said internal space connected to a fluid pressure source via a hydraulic circuit;
• a piston disposed within said internal space of said cylinder housing and dividing said internal space into said first and second fluid chambers, said first fluid chamber in fluid communication with said hydraulic circuit, said piston connected to said second member via a piston rod extending from sad cylinder housing, and said piston including a first fluid flow path for permitting a limited flow rate of fluid between said first and second fluid chambers;
• a pressure control valve means, disposed within said hydraulic circuit, for controlling introduction and draining of pressurized fluid into and from said first fluid chamber in order to adjust damping characteristics;
• a pressure accumulating unit having a body connected to said cylinder housing, said body defining a space in communication with said second fluid chamber via a second flow restricting fluid path and a third flow path permitting one-way fluid flow from a third chamber to said second fluid chamber;
• and
• a free piston assembly disposed within said space of said body for dividing said space onto said third fluid chamber and a pneumatic chamber, said third fluid chamber in communication with said second fluid chamber via said flow restricting fluid path, said free piston assembly movable depending upon a pressure difference between said third fluid chamber and said pneumatic chamber, for receiving pressurized fluid in said third fluid chamber when the fluid pressure in said second fluid chamber is higher than that in said third fluid chamber, for accumulating pressure and supplying pressure to said second fluid chamber when the fluid pressure in said second fluid chamber is lower than that in said third fluid chamber.

An actively controlled suspension system for automotive suspension, said actively controlled suspension system, comprising:

• a hydraulic cylinder assembly disposed between a vehicle body and a suspension member rotatably supporting a vehicular wheel, said hydraulic cylinder comprising:
• a cylinder housing defining an internal space filled with a working fluid and connected to said first member, said internal space connected to a fluid pressure source via a hydraulic circuit;
• a piston disposed within said internal space of said cylinder housing and dividing said internal space into first and second fluid chambers, said first fluid chamber in fluid communication with said hydraulic circuit, said piston connected to a second member via a piston rod expending from said cylinder housing, and said piston including a first fluid flow path for permitting limited flow rate of fluid between said first and second fluid chambers and a second fluid flow path for permitting one-way fluid flow from said second fluid chamber to said first fluid chamber;
• a pressure control valve means, disposed within said hydraulic circuit, for controlling introduction and training of pressurized fluid into and from said first fluid chamber in order to adjust damping characteristics;
• a free piston assembly disposed within said space of said body for dividing said space into a third fluid chamber and a pneumatic chamber, said third fluid chamber in communication with said second fluid chamber via said flow restricting fluid path, said free piston assembly movable depending upon a pressure difference between said third fluid chamber and said pneumatic chamber, for receiving pressurized fluid in said third fluid chamber when the fluid pressure in said second fluid chamber is greater than that in said third fluid chamber, for accumulating pressure and supplying pressure to said second fluid chamber when fluid pressure in said second fluid chamber is lower than that in said third fluid chamber;
• and
• a hydraulic means, interposed within said hydraulic circuit and associated with said first chamber of said hydraulic cylinder, for adjusting fluid pressure in said first chamber to control attitude of a vehicle so as to suppress attitude change of said vehicle body, said hydraulic means including a pressure source and a pressure control valve which is electrically controlled to introduce pressurized working fluid from said first chamber and to drain working fluid from said first chamber depending upon vehicle driving conditions.