Electrically actuated, hydraulic power steering system

A hydraulic power steering system for a motorized vehicle comprising:

• a hydraulic pump for generating hydraulic pressure;
• a hydraulic cylinder system having a first chamber of variable volume, a second chamber of variable volume, and at least one movable piston;
• a steering mechanism operatively engaged with the at least one piston of the hydraulic cylinder;
• a hydraulic fluid reservoir;
• a pressure accumulator selectively connected to the hydraulic pump and chargeable to a desired pressure;
• and
• a control valve arrangement operable to selectively connect the first and second chambers of the hydraulic cylinder to the pump, the pressure accumulator and the reservoir, the control valve arrangement operable in at least a first condition, a second condition, and a third condition;
• wherein:
• in the first condition the control valve arrangement connects the first chamber with the pump and connects the second chamber with the reservoir for fluid communication therebetween;
• in the second condition the control valve arrangement connects the first chamber with the reservoir and connects the second chamber with the pump for fluid communication therebetween;
• and
• in the third condition the control valve arrangement connects the first and second chambers with the pressure accumulator and disconnects the first and second chambers from the fluid reservoir.

A hydraulic power steering system for a motorized vehicle comprising:

• a hydraulic pump for generating hydraulic pressure;
• a hydraulic cylinder system having a first chamber of variable volume, a second chamber of variable volume, and at least one movable piston;
• a steering mechanism operatively engaged with the at least one piston of the hydraulic cylinder;
• a hydraulic fluid reservoir;
• a pressure accumulator selectively connected to the hydraulic pump and chargeable to a desired pressure;
• and
• a control valve arrangement operable to selectively connect the first and second chambers of the hydraulic cylinder to the pump, the pressure accumulator and the reservoir, the control valve arrangement operable in a least three conditions, wherein:
• in the first condition the control valve arrangement connects the first chamber with the pressure accumulator and connects the second chamber with the reservoir for fluid communication therebetween;
• in the second condition the control valve arrangement connects the first chamber with the reservoir and connects the second chamber with the pressure accumulator for fluid communication therebetween;
• and
• in the third condition the control valve arrangement connects the first and second chambers with each other and disconnects the first and second chambers from the reservoir.

A hydraulic power steering system for a motorized vehicle comprising:

• a hydraulic pump for generating hydraulic pressure;
• a hydraulic cylinder system having a first chamber of variable volume, a second chamber of variable volume, and at least one movable piston;
• a steering mechanism operatively engaged with the at least one piston of the hydraulic cylinder;
• a hydraulic fluid reservoir;
• a first pressure accumulator selectively connected to the hydraulic pump and chargeable to a first pressure;
• a second pressure accumulator selectively connected to the hydraulic pump and chargeable to a second pressure;
• and
• a control valve arrangement operable to selectively connect the first and second chambers of the hydraulic cylinder to the pump, the first pressure accumulator, the second pressure accumulator and the reservoir, the control valve arrangement operable in at least four conditions;
• wherein:
• in a first condition the control valve arrangement connects the first chamber with the first pressure accumulator and connects the second chamber with the reservoir for fluid communication therebetween;
• in a second condition the control valve arrangement connects the first chamber with the reservoir and connects the second chamber with the first pressure accumulator for fluid communication therebetween;
• in a third condition the control valve arrangement connects the first chamber with the second pressure accumulator and connects the second chamber with the reservoir for fluid communication therebetween;
• and
• in a fourth condition the control valve arrangement connects the first chamber with the reservoir and connects the second chamber with the second pressure accumulator for fluid communication therebetween.

A hydraulic power steering system for a motorized vehicle comprising:

• a hydraulic pump for generating hydraulic pressure;
• a hydraulic cylinder system having a first chamber of variable volume, a second chamber of variable volume, and at least one movable piston;
• a steering mechanism operatively engaged with the at least one piston of the hydraulic cylinder;
• a hydraulic fluid reservoir;
• a first pressure accumulator selectively connected to the hydraulic pump and chargeable to a first pressure;
• a second pressure accumulator selectively connected to the hydraulic pump and chargeable to a second pressure;
• and
• a control valve arrangement operable to selectively connect the first and second chambers of the hydraulic cylinder to the pump, the first pressure accumulator, the second pressure accumulator and the reservoir, the control valve arrangement operable in at least three conditions;
• wherein:
• in a first condition the control valve arrangement connects the first chamber with the second pressure accumulator and connects the second chamber with the reservoir for fluid communication therebetween;
• in a second condition the control valve arrangement connects the first chamber with the reservoir and connects the second chamber with the second pressure accumulator for fluid communication therebetween;
• and
• in a third condition the control valve arrangement connects the first and second chambers with the first pressure accumulator and disconnects the first and second chambers from the reservoir.

A hydraulic power steering system for a motorized vehicle comprising:

• a pump for generating hydraulic pressure;
• a hydraulic cylinder system having a first chamber of variable volume and a second chamber of variable volume;
• a steering mechanism operatively engaged to the hydraulic cylinder;
• a hydraulic fluid reservoir;
• a pressure accumulator selectively connected to the hydraulic pump and chargeable to a desired pressure;
• and
• a control valve arrangement operable to selectively connect the first and second chambers of the hydraulic cylinder to the pressure accumulator and the reservoir;
• wherein, when no steering assist is required, the control valve arrangement connects the first and second chambers with the pressure accumulator and disconnects the first and second chambers from the fluid reservoir.

A hydraulic power steering system for a motorized vehicle comprising:

• a hydraulic pump for generating hydraulic pressure;
• a hydraulic cylinder system having a first chamber of variable volume, a second chamber of variable volume, and at least one movable piston;
• a steering mechanism operatively engaged with the at least one piston of the hydraulic cylinder;
• a hydraulic fluid reservoir;
• a first pressure accumulator selectively connected to the hydraulic pump and chargeable to a first pressure;
• a second pressure accumulator selectively connected to the hydraulic pump and chargeable to a second pressure;
• a third pressure accumulator selectively connected to the hydraulic pump and chargeable to a third pressure;
• a steering sensor operatively engaged with the steering mechanism;
• a control valve arrangement operable to selectively connect the first and second chambers of the hydraulic cylinder to the pump, the first pressure accumulator, the second pressure accumulator, the third pressure accumulator and the reservoir, the control valve arrangement operable in at least seven conditions, wherein:
• the first condition is characterized by the first chamber being in fluid communication with the pump and the second chamber being in fluid communication with the fluid reservoir;
• the second condition characterized is by the first chamber being in fluid communication with the fluid reservoir and the second chamber being in fluid communication with the pump;
• the third condition is characterized by the first chamber being in fluid communication with the second pressure accumulator, and the second chamber being in fluid communication with the fluid reservoir;
• and
• the fourth condition is characterized by the first chamber being in fluid communication with the fluid reservoir, and the second chamber is in fluid communication with the second pressure accumulator.
• the fifth condition is characterized by the first chamber being in fluid communication with the third pressure accumulator, and the second chamber being in fluid communication with the fluid reservoir;
• the sixth condition is characterized by the first chamber being in fluid communication with the fluid reservoir, and the second chamber being in fluid communication with the third pressure accumulator;
• and
• the seventh condition is characterized by the first and second chambers being in fluid communication the first pressure accumulator and each other but not with the fluid reservoir;
• a control box operable to switch the control valve arrangement between said operating conditions in response, at least in part, to signals received from the steering sensor.