Self-pumping heat-pipe fuser roll

Abstract

An energy transfer device includes a heat pipe and at least one spiral feature on an interior surface along a portion of the heat pipe, wherein a pitch of the spiral feature may be such that a liquid is pumped in the heat pipe, and a thermal mass of the heat pipe is reduced by about 50%. The interiro spiral feature may be one of a spiral groove and a spiral fin. A method of manufacturing an energy transfer device may include providing a heat pipe, and providing at least one spiral feature via rotating extrusion on an interior surface along at least a portion of the heat pipe, wherein a pitch of the at least one spiral feature is such that a liquid is pumped in the heat pipe, and a thermal mass of the heat pipe is reduced by about 50%.

Description

BACKGROUND

Maintaining temperature uniformity of a fuser roll has long been a problem when varying media sizes in printing systems. In order to solve these uniformity issues, using a heat pipe as a fuser roll has been previously disclosed. Problems generally arise though in the complexity of the design of such heat pipe fuser rolls because the heat pipe generally acts as a closed system, and applying heat internally becomes difficult. Previous disclosures recommend applying heat at one end of the fuser roll, which simplifies the geometry of the subsystems. For instance, the following references describe heat pipes with specifically configured internal structures: U.S. application Ser. No. ______ (Attorney Docket No. 122311; Xerox ID # 20040275-US-NP); U.S. Pat. No. 4,773,476; “Helical Guide-Type Rotating Heat Pipe”, Shimizu, A. and Yamazaki, S., 6^th International Heat Pipe Conference, 1987; “Heat Transfer and Internal Flow Characteristics of a Coil-Inserted Rotating Heat Pipe”, Lee, J. and Kim, C., International Journal of Heat and Mass Transfer, 2001. A capillary wick is sometimes used to solve this problem, but the use of a capillary wick may limit the maximum heat flux supported by the heat pipe.

SUMMARY

By applying all the heat at one end of the system, the incident heat flux at that end is increased, and because there is a need to minimize the amount of water in the heat pipe for instant-on applications, there is a potential for dry-out, or film boiling, of the heat pipe evaporator. Moreover, inductively heated heat pipe fuser may require larger amounts of working fluids to operate at various angles of tilt. Larger amounts of working fluid are required to prevent dry-out at the heated end when the heated end is at a higher elevation that the portion of the heat pipe fuser roll delivering heat to the paper.

In light of these problems and shortcomings, various exemplary embodiments of devices and methods may provide an energy transfer device that includes a heat pipe and at least one spiral feature on an interior surface along at least a portion of the heat pipe, wherein a pitch of the at least one spiral feature is such that a liquid is pumped in the heat pipe during rotation of the heat pipe when liquid is present in the energy transfer device, and a pumping rate of the liquid is increased while vapor flow impedance is decreased, and thermal mass is decreased by about 50%. According to various exemplary embodiments, the heat pipe is a heat pipe fuser roll.

Moreover, various exemplary implementations may provide a manufacturing method of an energy transfer device that includes providing a heat pipe, and providing at least one spiral feature via rotating extrusion on an interior surface along at least a portion of the heat pipe, wherein a pitch of the at least one spiral feature is such that a liquid is pumped in the heat pipe during rotation of the heat pipe when liquid is present in the energy transfer device, and a pumping rate of the liquid is increased while vapor flow impedance decreases, and thermal mass is decreased by about 50%. According to various exemplary embodiments, the heat pipe is a heat pipe fuser roll.

Finally, various exemplary implementations provide a xerographic system that includes a heat pipe including at least one spiral feature on an interior surface along at least a portion of the heat pipe, and a controller that controls an operation of the heat pipe in the xerographic system, wherein a pitch of the at least one spiral feature is such that a liquid is pumped in the heat pipe during operation of the heat pipe by the controller, and a pumping rate of the liquid is increased while vapor flow impedance decreases, and thermal mass is decreased by about 50%. According to various exemplary embodiments, the heat pipe is a heat pipe fuser roll.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary implementations of systems are described in detail with reference to the following figures, wherein:

FIG. 1 is an illustration of an exemplary internal structure of a heat pipe fuser roll;

FIG. 2 is an illustration of the flow of liquid water through the fins of the exemplary heat pipe fuser roll;

FIG. 3 is a: curve illustrating the flow of the volume of liquid water with respect to the number of revolutions of the exemplary heat pipe fuser roll; and

FIG. 4 is a flow chart illustrating an exemplary method of manufacturing a heat pipe fuser roll.

DETAILED DESCRIPTION OF EMBODIMENTS

These and other features and advantages are described in, or are apparent from, the following detailed description of various exemplary embodiments.

FIG. 1 is an illustration of an exemplary internal structure of a heat pipe fuser roll. The heat pipe fuser roll 100 may be produced by a rotating die extrusion method, or may be produced with separately wound spirals 110. For example, using separately wound spring-like spirals 110 may allow pre-stressing the springs in compression before joining to the cylinder, thus increasing the load carrying capacity and stiffening the structure of the heat pipe fuser roll 100. For example, in order to account for 1000 watts of input, approximately 0.5 cc/sec of liquid to be transported to the heated end would be required. FIG. 1 illustrates three spiral fins 110 each with a pitch of about 3 times the diameter of the heat pipe fuser roll, which produces troughs for a roughly horizontal fuser which are approximately one diameter wide. If the fins 110 are 3 mm high and the heat pipe fuser roll 100 is 35 mm in diameter, then the trough volume is about 1.39 cc. In one revolution three troughs may be passing any axial point. If the structure is 100% efficient, about 4.17 cc/rev of liquid would be pumped, and the rotation speed would have to be about 0.12 rev/sec, or 7.2 rpm.

FIG. 2 is an illustration of the flow of liquid water through the fins of the exemplary heat pipe fuser roll 200. According to various exemplary embodiments, a full 3d, time transient model has a heat pipe fuser roll with an inner diameter of about 31.5 mm, fitted with a single fin 3 mm high with a pitch of 100 mm. An angular speed of 140 rpm, which is typical of the various fusers, is applied. In FIG. 2, at initial time t=0, quiescent liquid water is assumed within the trough defined by the fin height, which amounts to an initial volume of about 3.22 cc, or about 4.3% of the total interior volume of the fuser roll 200. As the heat pipe fuser roll rotates, the fin may push the liquid water towards the evaporator end as shown in the successive (quarter-revolution) frames 210, 220, 230, 240 and 250 in FIG. 2, which are the equivalent of snapshots of the flow of water through the fuser roll. The flow of the volume of water through the fuser roll 200 is quantified by monitoring the liquid water volume within the heat pipe fuser roll, as shown in FIG. 3. It should be noted that most of the liquid is forced towards the end of each turn when the trough created by the fins approaches the evaporator end of the pipe. At the end of the first turn, the liquid water volume may be 1.72 cc, which means that about 3.22−1.72=1.5 cc of liquid water has been pumped out. According to various exemplary embodiments, since, at 140 rpm, each turn occurs in about 0.43 s, the pumping rate is of approximately 1.5/0.43=3.5 cc/s, which is generally very adequate for a 1000 W input and may require about 0.5 cc/sec. Accordingly, the exemplary fuser roll 200 should easily deliver the required pumping rate for a desired performance. Since an ordinary heat pipe fuser roll requires approximately 10% volume to be water, the effects of the above-discussed self-pumping may result in an estimated 50% overall decrease in thermal mass of the fuser.

It should be noted that the fuser roll according to various exemplary implementations is not always 100% efficient, and the entire liquid volume is generally not pumped in a single turn because part of the liquid generally overflows to the other side of the fin, as indicated in frames see frames 230 to 250 of FIG. 2. This overflow issue may be remedied by having more fins and/or increasing the fin height. It should also be noted that the device efficiency may decrease as the operating angular speed increases because, at higher angular speeds, the liquid may begin to behave as a rigid body attaching itself to the inner walls of the heat pipe fuser roll.

FIG. 4 is a flowchart illustrating an exemplary manufacturing method of a heat pipe fuser roll. In FIG. 4, the method starts in step S100, and continues to step S110. During step S110, a heat pipe fuser roll may be provided. The control continues to step S120, during which interior ribs may be provided to various portions of the heat pipe fuser roll. The interior ribs may be either interior spiral grooves or interior spiral fins. The interior ribs may have a pitch of up to three times the diameter of the heat pipe fuser roll, and be configured so as to provide maximum liquid pumping and minimum vapor flow impedance and minimum thermal mass. Next, control continues to step S130, where the heat pipe fuser roll is evacuated. Next, control continues to step S140, where the heat pipe fuser roll is filled with water and sealed on both ends. Next, control continues to step S150, where the method ends.

It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Claims

1. An energy transfer device, comprising:

a heat pipe; and

at least one spiral feature on an interior surface along at least a portion of the heat pipe, wherein a pitch of the at least one spiral feature is such that a liquid is pumped in the heat pipe during rotation of the heat pipe when liquid is present in the energy transfer device, and a thermal mass of the heat pipe is reduced by about 50%.

2. The energy transfer device of claim 1, wherein the energy transfer device comprises at least one of a fuser roll, a photoreceptor, and a paper transport device.

3. The energy transfer device of claim 2, wherein the interior spiral feature comprises a spiral groove.

4. The energy transfer device of claim 2, further comprising an inductive heater to heat the heat pipe.

5. The energy transfer device of claim 4, wherein the inductive heater comprises induction coils located at least at one of one end of the heat pipe, along a length of the heat pipe, both ends of the heat pipe and inside the heat pipe.

6. The energy transfer device of claim 1, wherein the spiral fins are about 3 mm high.

7. The energy transfer device of claim 1, wherein the heat pipe is at least one of about 31.5 mm and about 35 mm in diameter.

8. The energy transfer device of claim 3, wherein the spiral fins have a pitch of at least one of about 3 times a diameter of the heat pipe and about 100 mm.

9. A method of using the energy transfer device of claim 1, comprising:

providing the heat pipe including the at least one spiral feature; and

rotating the heat pipe to pump a liquid at a rate of about 0.5 cc/sec.

10. A method of using the energy transfer device of claim 1, comprising:

providing the heat pipe including the at least one spiral feature; and

providing a volume of liquid of at least one of about 1.39 cc and about 3.22 cc into the energy transfer device.

11. A method of using the energy transfer device of claim 1, comprising:

providing the heat pipe including the at least one spiral feature; and

rotating the heat pipe to pump a liquid at a rate of about 4.17 cc per revolution.

12. A method of using the energy transfer device of claim 1, comprising:

providing the heat pipe including the at least one spiral feature; and

rotating the heat pipe at a speed of at least one of about 7.2 rpm and about 140 rpm.

13. A method of using the energy transfer device of claim 1, comprising:

providing the heat pipe including the at least one spiral feature; and

supplying about 1000 W to 1500 W of power to the heat pipe.

14. A method of manufacturing an energy transfer device, comprising:

providing a heat pipe; and

providing at least one spiral feature via rotating extrusion on an interior surface along at least a portion of the heat pipe, wherein a pitch of the at least one spiral feature is such that a liquid is pumped in the heat pipe during rotation of the heat pipe when liquid is present into the energy transfer device, and a thermal mass of the heat pipe is reduced by about 50%.

15. The method of claim 14, wherein the at least one spiral feature comprises a spiral groove.

16. A xerographic device comprising the energy transfer device of claim 1.

17. A xerographic system comprising:

a heat pipe fuser roll including at least one spiral feature on an interior surface along at least a portion of the heat pipe; and

a controller that controls an operation of the heat pipe fuser roll in the xerographic system, wherein a pitch of the at least one spiral feature is such that a liquid is pumped in the heat pipe during operation of the heat pipe by the controller.

18. The energy transfer device of claim 1, further comprising more than one evaporator section, and wherein the heat pipe comprises two sets of spiral features, each set of spiral features pumping liquid outward from the center of the heat pipe to ends of the heat pipe, and heating provided at each one of the ends of the heat pipe.

19. The energy transfer device of claim 2, wherein the interior spiral feature comprises a spiral fin.

20. The method of claim 14, wherein the at least one spiral feature comprises a spiral fin.