We claim:
1. A hydraulic pumpmotor, comprising:
a drive shaft mounted in a manifold block on a central axis;
a torque plate coupled to said drive shaft for torque transmission therebetween;
a bent axis motive unit having a base connected to said manifold block for arcuate translation about a swivel axis transverse to said central axis;
a cylinder block supported for rotation on said base and having hollow pistons in blind cylinders in said cylinder block, said pistons having spherical piston heads engaged in spherical sockets in said torque plate;
fluid flow channels communicating through said torque plate for conveying fluid pressurized in said cylinders when said pistons are driven into said cylinders by rotation of said cylinder block around said yoke when it is tilted at an angle to present said cylinder block to said torque plate at a diverging axis.
2. A hydraulic pumpmotor as defined in claim 1, wherein:
said torque plate has a hydrostatic fluid bearing for supporting said torque plate on a pressurized fluid film on said manifold block.
3. A hydraulic pumpmotor as defined in claim 2, wherein:
said hydrostatic fluid bearing includes an underbalance portion provided by fluid pressure in said fluid flow channels communicating through said torque plate, and an overbalance portion having shallow individual recesses that are supplied with fluid under system pressure through an orifice in said individual recesses, said orifices having a limited flow rate into said recesses at system pressure;
whereby fluid pressure in said recesses separates said torque plate from said manifold block and leaks out of said recesses at a rate that exceeds said limited flow rate through said orifices, creating a fluid pressure drop across said orifices and thereby reducing the axial force exerted by said overbalance portion until the axial spacing between the torque plate and said manifold block reaches an equilibrium where the axial force exerted by the two hydrostatic bearings just balances the axial force exerted by said pistons on said torque plate.
4. A hydraulic pumpmotor as defined in claim 1, wherein:
said base includes a yoke having a pair of arms projecting from a yoke base, each arm being pivotally connected to said manifold block for pivoting about said pivotal axis lying in a plane that also containing centers of curvature of said spherical piston heads;
whereby said cylinder block remains on its axis of rotation about said bent axis regardless of tilt angle of said yoke.
5. A hydraulic pumpmotor as defined in claim 1, further comprising:
a control piston in a control cylinder, said control piston being positionable in said control cylinder by positioning a control rod attached to a control spool inside a bore in said control piston.
6. A hydraulic pumpmotor as defined in claim 1, wherein:
said base includes a slide block having a cylindrical rear face that slides in a cylindrical recess of a support block.
7. A hydraulic pumpmotor as defined in claim 6, further comprising:
a control piston in a control cylinder, said control piston being positionable in said control cylinder by positioning a control rod attached to a control spool inside a bore in said control piston;
said slide block has a central opening that receives a pin projecting from said control piston for controlling said tilt angle that said cylinder block axis makes with a central axis of said drive shaft.
8. A hydraulic pumpmotor as defined in claim 1, further comprising:
a radial bearing for radially supporting said torque plate in position on said manifold block.
9. A hydraulic pumpmotor as defined in claim 8, wherein:
said radial bearing surrounds said torque plate and reacts transverse loads exerted on said torque plate by said pistons through said radial bearing directly to a supporting cylindrical sleeve connected to said manifold block.
10. A hydraulic pumpmotor as defined in claim 8, wherein:
said radial bearing surrounds said drive shaft and supports said torque plate indirectly by virtue of a coupling between said drive shaft and said torque plate.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. A print head for a pagewidth printer, the print head comprising
a substrate that defines a plurality of ink inlet channels; and
a plurality of nozzle arrangements that is positioned on the substrate, the nozzle arrangements being the product of an integrated circuit fabrication process and being in fluid communication with the ink inlet channels, and defining a pattern which is the result of carrying out successive replications of one nozzle arrangement with predetermined rotations and multipliers on a reference grid.
2. A print head as claimed in claim 1, in which the nozzle arrangements define a pattern generated by positioning a nozzle arrangement at an angle of approximately 45 degrees to an axis of the reference grid and replicating the nozzle arrangement without rotation to obtain a first group of nozzle arrangements.
3. A print head as claimed in claim 2, in which the nozzle arrangements define a pattern generated by replicating the first group of nozzle arrangements a predetermined number of times with a 180 degree rotation to obtain a second group of nozzle arrangements.
4. A print head as claimed in claim 3, in which the nozzle arrangements define a pattern generated by replicating the second group of nozzle arrangements a predetermined number of times with no rotation to obtain a third group of nozzle arrangements.
5. A print head as claimed in claim 4, in which the nozzle arrangements define a pattern generated by replicating the third group of nozzle arrangements a predetermined number of times with no rotation to obtain a fourth group of nozzle arrangements.
6. A print head as claimed in claim 5, in which the nozzle arrangements define a pattern generated by replicating the fourth group of nozzle arrangements a predetermined number of times with no rotation to obtain a fifth group of nozzle arrangements.
7. A print head as claimed in claim 6, in which the nozzle arrangements define a pattern generated by replicating the fifth group of nozzle arrangements a predetermined number of times with no rotation to obtain a sixth group of nozzle arrangements.
8. A print head as claimed in claim 7, in which the nozzle arrangements define a pattern generated by replicating the sixth group of nozzle arrangements a predetermined number of times with no rotation to obtain a seventh group of nozzle arrangements.
9. A method of fabricating print head, the method comprising the steps of:
forming a unit cell on a reference grid, the unit cell representing a nozzle arrangement to be fabricated on a substrate;
carrying out successive replications on the unit cell with predetermined rotations and multipliers to form a plurality of unit cells on the reference grid; and
fabricating a plurality of nozzle arrangements on the substrate using the plurality of unit cells.
10. A method as claimed in claim 9, which includes the step of positioning the unit cell at an angle of 45 degrees relative to an axis of the reference grid and replicating the unit cell a predetermined number of times without rotation to obtain a first group of unit cells.
11. A method as claimed in claim 10, which includes the step of replicating the first group of unit cells a predetermined number of times with a rotation of 180 degrees to obtain a second group of unit cells.
12. A method as claimed in claim 11, which includes the step of replicating the second group of unit cells a predetermined number of times without rotation to obtain a third group of unit cells.
13. A method as claimed in claim 12, which includes the step of replicating the third group of unit cells a predetermined number of times without rotation to obtain a fourth group of unit cells.
14. A method as claimed in claim 13, which includes the step of replicating the fourth group of unit cells a predetermined number of times without rotation to obtain a fifth group of unit cells.
15. A method as claimed in claim 14, which includes the step of replicating the fifth group of unit cells a predetermined number of times without rotation to obtain a sixth group of unit cells.
16. A method as claimed in claim 15, which includes the step of replicating the sixth group of unit cells a predetermined number of times without rotation to obtain a seventh group of unit cells.