Motors: expansible chamber type – Three or more cylinders arranged in parallel radial or... – Cylinders parallel to rotation axis
Reexamination Certificate
1999-09-03
2001-07-10
Lopez, F. Daniel (Department: 3745)
Motors: expansible chamber type
Three or more cylinders arranged in parallel radial or...
Cylinders parallel to rotation axis
Reexamination Certificate
active
06257119
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to hydraulic units of the bent axis type. More particularly, this invention relates to a swinging yoke type bent axis hydraulic unit.
Bent axis hydraulic units have been known for many years. The most widespread or common of the bent axis designs utilizes a “tilting block” such as disclosed by Forster in U.S. Pat. No. 4,893,549. A rotatable cylindrical drum or cylinder block kit has a plurality of axial pistons therein supported on a nonrotatable swivel carriage on its axis of rotation. The swivel carriage has a convex end face positioned against a concave swivel carriage guide surface. The swivel carriage guide surface is part of the swivel carriage housing, which is attached to the machine housing by a flange connection. The cylinder block kit and carriage tilt or pivot to vary displacement.
Other bent axis units utilize a “swinging yoke” configuration. The cylinder block kit is carried by the yoke and swings with it to vary the displacement of the unit. There is a need for a swinging yoke bent axis hydraulic unit which incorporates some of the best features of both the tilting block and swinging yoke configurations.
A primary objective of the present invention is the provision of a swinging yoke bent axis hydraulic unit having up to greater than plus or minus 45° of yoke swing as a result of a ball joint between the actuator and the yoke.
Another objective of this invention is the provision of an actuator rod and socket for connecting a servo piston and a swinging yoke such that the rod can move in more than one plane.
Another objective of this invention is the provision of a substantially spherical socket for connecting the actuator rod and the yoke with multiple degrees of freedom.
Another objective of this invention is the provision of bent axis angles up to greater than 90° to maximize the power density of the hydraulic unit.
Another objective is the provision of a socket joint with multiple degrees of freedom in combination with a servo piston which is tiltable within its bore.
Another objective of this invention is a swinging yoke bent axis configuration which is easy to assemble, economical to produce, keeps the number of required parts to a minimum, and is durable and reliable in use.
These and other objectives will be apparent from the drawings, as well as from the description and claims which follow.
SUMMARY OF THE INVENTION
The present invention relates to a special ball joint for servo piston actuation of a bent axis unit. The ball joint includes an elongated actuator rod having a substantially spherical external surface on a first end and a servo piston on a second end. Also included is a yoke adapted to carry a cylinder block and rotate about an axis of rotation. A socket having a substantially spherical surface is interposed between the yoke and the spherical surface on the rod such that the actuator rod rotates the yoke when hydraulic pressure is applied to the servo piston. Two servo pistons and two such ball joints can be applied to rotate the yoke to angles up to greater than plus or minus 45° from a neutral position. The external surface on the first end of the actuator rod and the socket must be mating so as to provide freedom of movement. The socket can be incorporated into the yoke itself.
REFERENCES:
patent: 2931250 (1960-04-01), Ebert
patent: 3142963 (1964-08-01), Thoma
patent: 3148628 (1964-09-01), Boydell
patent: 3958496 (1976-05-01), Wallin
patent: 4273517 (1981-06-01), Heyl
patent: 4843950 (1989-07-01), Heyl
patent: 4893549 (1990-01-01), Forster
“Data Sheet for Variable Pump/Motor V20,” Volvo Hydraulics, pp. 1-4, published prior to 1980.
“Hydrostatics for power split transmission,” E. Skirde & M. Gigling, Industrial Vehicle Technology '98, pp. 30-33, published 1998.
Dirks David D.
Gollner Wilhelm
Kardell Doug
Ryken James D.
Lopez F. Daniel
Sauer-Danfoss Inc.
Zarley McKee Thomte Voorhees & Sease
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