# US 9,751,321 B2 · Gear pump and printing apparatus provided with same

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- Number: US 9,751,321 B2
- Document ID: US9751321B2
- Status: Granted
- Kind: B2
- Application number: 15/095,250
- Filed: 2016-04-11
- Published: 2016-10-20
- Granted: 2017-09-05
- Earliest claimed: 2015-04-17
- Assignees: Seiko Epson Corporation
- Applicants: Seiko Epson Corporation
- Inventors: Masaaki Ando; Noritaka Mitsuo; Norihiro Maruyama
- Web page: https://patentgrep.com/patent/US9751321B2

## CPC

- B41J 2/17596: {Ink pumps, ink valves}
- B41J 2/175: Ink supply systems {; Circuit parts therefor}
- B41J 2/18: Ink recirculation systems
- B41J 29/38: Drives, motors, controls or automatic cut-off devices for the entire printing mechanism
- F01C 21/02: Arrangements of bearings (bearing constructions F16C)
- F01C 21/10: Outer members for co-operation with rotary pistons; Casings (casings for rotary engines or machines in general F16M)
- F04C 2/086: {Carter}
- F04C 2/14: with toothed rotary pistons
- F04C 13/001: {Pumps for particular liquids}
- F04C 15/06: Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
- F04C 2210/205: Ink
- F04C 2240/60: Shafts
- F04C 2270/17: Tolerance; Play; Gap
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- F01C: ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES (internal-combustion aspects F02B53/00, F02B55/00)
- F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS

## Abstract

A gear pump for transporting a fluid includes a pump casing; and a gear assembly which is accommodated in the pump casing. The gear assembly includes a driving gear, a driven gear that mashes with the driving gear, a driving gear shaft to which the driving gear is attached, a driven gear shaft to which the driven gear is attached, and a bearing frame that rotatably supports the driving gear shaft and rotatably supports the driven gear shaft.

## Claims

### Claim 1

A gear pump for transporting a fluid comprising:
a pump casing; and
a gear assembly which is accommodated in the pump casing,
the gear assembly including
a driving gear,
a driven gear that meshes with the driving gear,
a driving gear shaft to which the driving gear is attached,
a driven gear shaft to which the driven gear is attached, and
a bearing frame that rotatably supports the driving gear shaft and rotatably supports the driven gear shaft,
the bearing frame includes
a frame main body,
a pair of driving side bearing portions which is provided in the frame main body and which supports the driving gear shaft at both ends thereof, and
a pair of driven side bearing portions which is provided in the frame main body and which supports the driven gear shaft at both ends thereof,
each of the driving side bearing portions and the driven side bearing portions being formed of a journal bearing which is separate from the frame main body,
each of the driving gear shaft, the driven gear shaft, the driving side bearing portions, and the driven side bearing portions being formed of an alumina ceramic.

### Claim 2

A gear pump for transporting a fluid comprising:
a pump casing; and
a gear assembly which is accommodated in the pump casing,
the gear assembly including
a driving gear,
a driven gear that meshes with the driving gear,
a driving gear shaft to which the driving gear is attached,
a driven gear shaft to which the driven gear is attached, and
a bearing frame that rotatably supports the driving gear shaft and rotatably supports the driven gear shaft,
the bearing frame includes
a frame main body,
a pair of driving side bearing portions which is provided in the frame main body and which supports the driving gear shaft at both ends thereof, and
a pair of driven side bearing portions which is provided in the frame main body and which supports the driven gear shaft at both ends thereof,
each of the driving side bearing portions and the driven side bearing portions being formed of a journal bearing which is separate from the frame main body,
the frame main body being integrally formed by a pair of bearing support portions, in which the driving side bearing portion and the driven side bearing portion are provided, and a pair of connecting portions which connects the pair of bearing support portions,
a clearance between an end surface of the driving gear and an opposed surface of each bearing support portion that opposes the end surface being 50 μm or more,
a clearance between an end surface of the driven gear and an opposed surface of each bearing support portion that opposes the end surface being 50 μm or more,
each of the driving gear and the driven gear being formed of polyethylene terephthalate.

### Claim 3

A gear pump for transporting a fluid comprising:
a pump casing; and
a gear assembly which is accommodated in the pump casing,
the gear assembly including
a driving gear,
a driven gear that meshes with the driving gear,
a driving gear shaft to which the driving gear is attached,
a driven gear shaft to which the driven gear is attached, and
a bearing frame that rotatably supports the driving gear shaft and rotatably supports the driven gear shaft,
the bearing frame including
a frame main body,
a pair of driving side bearing portions which is provided in the frame main body and which supports the driving gear shaft at both ends thereof, and
a pair of driven side bearing portions which is provided in the frame main body and which supports the driven gear shaft at both ends thereof,
each of the driving side bearing portions and the driven side bearing portions being formed as a separate member from the frame main body, the driving side bearing portions being disposed between the driving gear shaft and the frame main body, the driven side bearing portions being disposed between the driven gear shaft and the frame main body,
the frame main body further including a pair of bearing support portions, and a pair of connecting portions extending between the bearing support portions, with the connecting portions being opposite to each other in a direction perpendicular to an axial direction of the driving gear shaft and at least partially sandwiching the driving gear and the driven gear therebetween, one of the connecting portions having an inflow port for the fluid, the other one of the connecting portions having an outflow port for the fluid.

### Claim 4 (depends on 3)

The gear pump according to claim 3, wherein
the frame main body is integrally formed by the bearing support portions and the connecting portions, the driving side bearing portions and the driven side bearing portions being provided in the bearing support portions, and the connecting portions connecting the bearing support portions.

### Claim 5 (depends on 4)

The gear pump according to claim 4, wherein
a clearance between an end surface of the driving gear and an opposed surface of each bearing support portion that opposes the end surface is 50 μm or more, and
a clearance between an end surface of the driven gear and an opposed surface of each bearing support portion that opposes the end surface is 50 μm or more.

### Claim 6 (depends on 4)

The gear pump according to claim 4, wherein
each of the connecting portions is formed in a plate shape, the inflow port connecting to an intake port of the pump casing, the outflow port connecting to a discharge port of the pump casing.

### Claim 7 (depends on 3)

The gear pump according to claim 3, wherein
each of the driving side bearing portions and the driven side bearing portions is formed of a journal bearing which is separate from the frame main body.

### Claim 8 (depends on 3)

The gear pump according to claim 3, wherein
the fluid is an ultraviolet-curable ink.

### Claim 9 (depends on 8)

A printing apparatus comprising:
a print head that performs printing by discharging an ultraviolet-curable ink to a printing medium;
a circulation flow path that supplies the ultraviolet-curable ink to the print head; and
a circulation pump inserted in the circulation flow path,
wherein the circulation pump is formed of the gear pump according to claim 8.