Claims
- 1. A hybrid electric hydraulic drive system, comprising:
- a first hydraulic cylinder having a left chamber and a right chamber separated by a piston;
- a second hydraulic cylinder having a sole fluid chamber for receiving hydraulic fluid, said second hydraulic cylinder enclosing a second piston, said second hydraulic cylinder being substantially equal in length to said first hydraulic cylinder and being attached rigidly in parallel thereto;
- a pump fluidly connected to said left chamber by a first fluid passage said fluidly connected to said right chamber by a second fluid passage;
- a third fluid passage directly connected to said first hydraulic cylinder and to said sole fluid chamber of said second hydraulic cylinder;
- a controller;
- an electric motor for driving said pump, said electric motor being electrically connected to said controller;
- a first rod connected to said piston;
- a second rod connected to said second piston;
- an encoder, said encoder being electrically connected to said controller;
- a connecting element connecting said first rod and said second rod, so said first rod and said second rod move in unison; and
- wherein said sole chamber has a volume equal to the volume of said first rod, said first rod displacing fluid in said right chamber of said first hydraulic cylinder.
- 2. A system according to claim 1, wherein:
- the total fluid capacity of the system remains constant during operation.
- 3. The system of claim 2, wherein:
- said third fluid passage fluidly connects said right chamber with said sole fluid chamber.
REFERENCE
The information, data and all benefits of provisional application Ser. No. 60/096,327 filed Aug. 12, 1998 are incorporated by reference into this description.
US Referenced Citations (10)