Hybrid Recirculating/Vented Tumble Dryer With Purposeful Fresh Air Inlet At Drying Chamber
A hybrid vented tumble dryer which includes a drying chamber such as a rotatable drum, a heater, a process air fan, a recirculation duct, and a process air circuit configured to recirculate process air through the dryer. The dryer may include first and second drum seal gaskets located between the drum and first and second bulkheads, respectively. In some embodiments, the recirculation duct is in closed fluid communication with the heater. In other embodiments, the process air circuit is configured such that substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater, or such that substantially the only fresh air which enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, after the heater and before an outlet of the drying chamber.
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The present invention relates generally to laundry dryers. In particular, the invention relates to a hybrid vented tumble dryer, i.e., a dryer that recirculates and exhausts drying air.
BACKGROUNDA traditional vented tumble dryer removes moisture from clothing and other articles by drawing heated air across the damp articles placed within a rotating drum. For example,
This traditional vented tumble dryer 100 is not a very efficient machine. Specifically, and particularly when a small load of articles 112 is placed within the drying chamber 108 to be dried, the heated process air 103 entering the drying chamber 108 may not interact optimally with the damp articles 112 for removing moisture therefrom before it is exhausted from the dryer 100 at the exhaust duct 116. Accordingly, when the process air 105 is exhausted from the dryer 100, energy used to heat the process air 105 (which has additional drying potential) is wasted.
In an effort to thus improve the efficiency of the traditional vented tumble dryer 100, some dryers recirculate a portion of the process air 105 leaving the drying chamber 108. That is, as discussed, the process air 105 leaving the drying chamber 108 may still hold the potential to absorb additional water. When this process air 105 is recirculated (e.g., directed back into the drying chamber 108), it performs further drying of the articles 112, thus improving the overall efficiency of the machine. These “hybrid” vented tumble dryers (“hybrid” in the sense that a portion of the process air is recirculated and a portion of the process air is exhausted) thus recapture otherwise lost drying potential of the heated process air 103 rather than simply exhausting the entirety of the process air 105 from the system after a single pass.
For example,
However, because fresh air 218 enters the system at, e.g., drum seal gaskets or the like at the drying chamber 208, the entirety of the recirculated process air 207 may not actually be reintroduced into the process air circuit at the inlet duct 202. More particularly, the flow rate of the recirculated process air 207 cannot exceed a physical limit fixed by the flow limits of the process air fan 210 and the amount of fresh air 218 which enters the drying chamber 208. This may be better understood with reference to a specific example.
First, returning to the traditional vented tumble dryer 100 in
When this system is modified into the hybrid vented tumble dryer 200 to improve efficiency as discussed, the flow rate of the process air 205 through the system will nonetheless still be capped by the flow rate of the process air fan 210. So, returning to the example where the process air fan 210 draws 180 m3/h of process air 205 through the system, and 80 m3/h of fresh air 218 enters the drying chamber 208 due to leakage at the drum seal gaskets, the flow rate of the supply process air 203 (i.e., the recirculated process air 207 combined with the fresh air 218 entering the system at the air inlet 201) will be capped at 100 m3/h. In that regard, if the dryer 200 is configured to recirculate the recirculated process air 207 at 100 m3/h or less, then the entirety of the recirculated process air may be reintroduced into the system at the supply duct 202. However, if the dryer 200 is configured such that the recirculated process air 207 is recirculated at a greater flow rate than 100 m3/h, only a maximum of 100 m3/h of that recirculated process air 207 will be reintroduced into the system at the supply duct 202, with the remaining portion of the process air 207 escaping from the system into an interior of a cabinet of the dryer 200 through the air inlet 201 (schematically represented by escaping process air 209 in
Accordingly, and returning to the above example, if the process air fan 210 is configured to draw 180 m3/h of process air 205 and the hybrid vented tumble dryer 200 is configured to recirculate, e.g., 130 m3/h of the process air 207, but 80 m3/h of fresh air 218 enters the drying chamber 208 via leakage at the drum seal gaskets, only 100 m3/h of the recirculated process air 207 will actually be pulled through the supply duct 202. The remaining 30 m3/h of the recirculated process air 207 will escape to (and may ultimately condense within) an interior of the cabinet of the dryer 200. Accordingly, the interior of the dryer 200 may be damaged.
Ideally, the hybrid vented tumble dryer 200 is designed such that a near maximum amount of process air 207 is recirculated (which still has the potential to absorb additional water) while preventing any portion of this recirculated process air 207 escaping into the interior of the dryer's cabinet immediately upstream of the supply duct 202 at the air inlet 201. However, over time the drum seal gaskets of the dryer 200 may begin to wear, allowing more fresh air 218 to enter the system at the drying chamber. In this regard, even if the dryer 200 is originally designed such that no portion of the recirculated process air 207 escapes into a cabinet at the air inlet 201, over time the originally designed flow rate of the recirculation process air 207 may be too high. That is, with the additional fresh air 218 entering around the worn drum seal gaskets, the originally configured flow rate of the recirculated process air 207 may be too high for the flow rate capped by the process air fan 210, and accordingly a portion of the recirculated process air 207 may escape to the interior of the hybrid vented tumble dryer 200 at the air inlet 201.
Accordingly, there remains a need for a vented tumble dryer which exhibits improved efficiency over a traditional vented tumble dryer, and which overcomes one or more of the above-discussed deficiencies associated with recirculating a portion of the process air. More particularly, there remains a need for a hybrid vented tumble dryer which recirculates a portion of the process air in order to increase efficiency, but which is more effective in preventing the recirculated process air from escaping into an interior of the hybrid vented tumble dryer.
BRIEF SUMMARY OF SELECTED INVENTIVE ASPECTSThe instant disclosure is directed to a hybrid vented tumble dryer which overcomes one or more of the above-discussed deficiencies of known hybrid vented tumble dryers.
According to a first aspect of the invention, a hybrid vented tumble dryer includes a drying chamber, a heater configured to heat process air entering the drying chamber, a process air fan configured to draw the process air through the drying chamber, an exhaust duct configured to exhaust a first portion of the process air from the drying chamber, a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater, and a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer. The process air circuit is defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct. Further, the process air circuit is configured such that the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, and the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater. The process air circuit is also configured such that substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater.
According to another aspect of the invention, the drying chamber of the hybrid vented tumble dryer includes an inlet and an outlet with the process air moving through the drying chamber entering at the inlet and exiting at the outlet. In such embodiments, substantially the only fresh air that enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, at a location after the heater but before the outlet of the drying chamber.
According to still another aspect of the invention, the hybrid vented tumble dryer includes a rotatable drum, a first and second bulkhead, and a first and second drum seal gasket. The first drum seal gasket is located between the rotatable drum and the first bulkhead in a non-airtight manner and the second drum seal gasket is located between the rotatable drum and the second bulkhead in the non-airtight manner such that the fresh air can enter the rotatable drum at the first and second drum seal gaskets. In such embodiments, the recirculation duct is in closed fluid communication with the heater.
The above and other features, aspects, and advantages of the invention will be fully apparent and understood from the following detailed description, taken together with the appended drawings, wherein:
As schematically seen in
The recirculated process air 307 is then reintroduced to the supply duct 302, and then flows again through the process air circuit as described. Notably, however, the recirculated process air 307 is not mixed with fresh air at the supply duct 302 before passing across the heater 306. More specifically, unlike the hybrid vented tumble dryer 200 discussed above in connection with
The above may be better understood with reference to the example embodiments of the hybrid vented tumble dryer depicted in
The rotatable drum 426 is rotatably supported between the rear bulkhead 428 and a front bulkhead 430. More particularly, and as best seen in
The rotatable drum 426 is configured to be rotated by a motor 502 (
As discussed, and referring to
In the embodiment depicted in
In this embodiment, the recirculation duct 620 includes a removable recirculation air filter 642 (as best seen in
A recirculation filter housing 640 is provided at an uppermost portion of the recirculation duct 620 which houses the accessible recirculation air filter 642 therein and which has an open end in communication with the access opening 432 (such that a user may remove and clean the recirculation air filter 642 from inside the drying chamber 408 as necessary). The housing 640 removably houses the recirculation air filter 642 such that airflow spacing is provided along one or more sides of the recirculation air filter 642. In this regard, the recirculated process air 307 is directed generally vertically via recirculation duct 620 into the housing 640 and through the recirculation air filter 642, with the recirculated process air 307 exiting the filter 642 along one or more sides of the filter 642. Accordingly, residual lint or debris (i.e., lint or debris that remains in the process air 305 after it passes through the lint filter 414) is removed from the recirculated process air 307 before the recirculated process air 307 is reheated by the heater 406 provided at the heater canister 402, as is described in more detail in commonly owned U.S. patent application Ser. No. 13/912,580, filed Jun. 7, 2013, and entitled “Laundry Dryer with Accessible Recirculation Air Filter,” which is hereby incorporated by reference in its entirety. Finally, the recirculation duct 620 extends generally horizontally and rearwardly downstream of the housing 640, where it fluidly connects to the heater canister 402 in a closed manner, i.e., without any fresh air inlet provided.
In any of the above described embodiments, the recirculation duct 420, 620 is in closed fluid communication with the heater canister 402 (i.e., an open fresh air inlet is not provided immediately upstream of the heater canister 402). Accordingly, and as discussed in connection with
In
The heated process air 307 also mixes with the fresh air 318 (i.e., air that flows relatively freely into and within the cabinet of dryer 300) inside the drying chamber 408. More particularly, the front drum seal gasket 434 and the rear drum seal gasket 436 are configured in a non-airtight manner such that a desired amount of the fresh air 318 can enter the process air circuit at the drum seals. For example, in one suitable embodiment, the gaskets 434, 436 are configured such that airflow spacing is provided between the front gasket 434 and the rotatable drum 426 and/or the front bulkhead 430, and/or such that airflow spacing is provided between the rear gasket 436 and the rotatable drum 426 and/or the rear bulkhead 428. For example, the mechanical properties of the gaskets 434, 436, bulkheads 428, 430, and/or the drum 426 may be configured such that there is less pressure (i.e., sealing action) between the gaskets 434, 436 and the respective end 1108, 1110 of the drum 426 and/or the respective bulkhead 430, 428, allowing a desired amount of fresh air 318 to enter the process air circuit at the drum seal gaskets 434, 436. Additionally or alternatively, the drum 426 may include one or more small gaps and/or holes provided around its circumference, allowing a desired amount of fresh air 318 to enter the process air circuit at the drum seal gaskets 434, 436. In another suitable embodiment, the gaskets 434, 436 may be constructed of an air-permeable material such that the fresh air 318 can enter the drying chamber 402 through the air-permeable gaskets 434, 436. Accordingly, the fresh air 318, which is at a higher pressure than the air provided within the drying chamber 408 due to the operation of the process air fan 410, is drawn into the drying chamber 408 around the ends 1108, 1110 of the rotatable drum 426 (i.e., at the drum seal gaskets 434, 436) and mixes with the heated process air 307 entering the drying chamber 408 via the drum inlet 1102.
The process air 305 (i.e., the heated process air 307 mixed with the fresh air 318) is then drawn, via operation of the process air fan 410, through an opening in the front bulkhead 430 and through the lint filter 414, with a portion thereof ultimately recirculated to the heater canister 402 via the recirculation duct 420. Because, as discussed, the recirculation duct 420 is in closed fluid communication with the heater canister 402, the recirculated process air 307 is reintroduced to the heater canister 402 but is not mixed with any fresh air at this point. Accordingly, substantially the only fresh air 318 which enters the process air circuit enters at the rotatable drum 426 (with only negligible amounts of fresh air, if any, entering at other portions of the process air circuit due to, e.g., leakage at the process air fan 410 casing, leakage around the lint filter 414, leakage at the access door, leakage at the seams of the ducting, etc.). The recirculated process air 307 is then reheated by passing over the heater 306, and ultimately is drawn once again through the process air circuit as described above.
Although in the above-described embodiments substantially the only fresh air which enters the process air circuit enters at the drum seal gaskets 434, 436, in other embodiments fresh air 318 may be drawn into the process air circuit at other suitable locations while still omitting the air inlet 201 discussed in connection with
When configured as discussed above, the hybrid vented tumble dryer 400 exhibits benefits over the known hybrid vented tumble dryer 200. For example, the dryer 400 does not include an air inlet immediately upstream of the heater canister 402 (unlike the air inlet 201 provided immediately upstream of the supply duct 202), but rather the recirculation duct 420 is in closed fluid communication with the heater canister 402. Accordingly, even if over time one or both of the front drum seal gasket 434 and the rear drum seal gasket 436 begin to wear, thus allowing more fresh air 318 to enter the process air circuit around the ends of the rotatable drum 426, the recirculated process air 307 will nonetheless not escape into an interior of the dryer 400 (unlike the known hybrid vented tumble dryer 200). This configuration thus reduces the chance of damage to internal components of the dryer 400 which could otherwise be caused by condensation of the escaping process air 209. Rather, if and when the drum seal gaskets 434, 436 begin to wear, the hybrid vented tumble dryer 400 may simply “self-tune.” That is, dryer 400 will simply operate with a different air mixture (e.g., a little more fresh air 318 and a little less recirculated process air 307) without risk of moisture-laden process air escaping to the internal components.
Additionally, because in some embodiments the only fresh air 318 entering the process air circuit of the dryer 400 enters around the ends 1108, 1110 of the rotatable drum 426 at the drum seal gaskets 434, 436, an air-restriction property of the gaskets can be relaxed as compared to the traditional vented tumble dryer 100 or the known hybrid vented tumble dryer 200. More particularly, in the dryers 100, 200, the drum seal gaskets may be designed to minimize or reduce as much as possible any fresh air 118, 218 from entering the process air circuit around the ends of a respective rotatable drum. In contrast, for the dryer 400, the air-restriction properties of the front drum seal gasket 434 and the rear drum seal gasket 436 may be configured (i.e., relaxed) such that a desired amount of fresh air 318 is allowed to enter the drying chamber 408 around the ends 1108, 1110 of the rotatable drum 426. In this regard, the front drum seal gasket 434 and rear drum seal gasket 436 may exhibit less frictional resistance when the rotatable drum 426 is rotated by the motor 502 than if the gaskets 434, 436 were configured to reduce as much as possible the fresh air 318 leaking into the drum (as is with the traditional vented tumble dryer 100 and the known hybrid vented tumble dryer 200). Accordingly, the motor 502 may require less power to rotate the rotatable drum 426 than otherwise would be needed for the dryers 100, 200, thus improving overall machine efficiency.
Further, by designing the hybrid vented tumble dryer 300 such that the only fresh air 318 entering the process air circuit is around the ends 1108, 1110 of the rotatable drum 426 at the drum seal gaskets 434, 436, overall manufacturing costs of the machine may be reduced. Specifically, the dryer 400 may require less parts to form the recirculation channel 420 than the known hybrid vented tumble dryer 200, which requires, e.g., additional ducting extending to the fresh air intake 201.
The present invention has been described in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from the review of this disclosure.
Claims
1. A hybrid vented tumble dryer comprising:
- a drying chamber;
- a heater configured to heat process air entering the drying chamber;
- a process air fan configured to draw the process air through the drying chamber;
- an exhaust duct configured to exhaust a first portion of the process air from the drying chamber;
- a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater; and
- a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer and defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct, wherein the process air circuit is configured such that: the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater, and substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater.
2. The hybrid vented tumble dryer of claim 1, further comprising at least one gasket, wherein substantially the only fresh air which enters the process air circuit enters directly into the drying chamber at the at least one gasket.
3. The hybrid vented tumble dryer of claim 2, wherein the drying chamber is a rotatable drum configured to rotate with respect to a bulkhead of the hybrid vented tumble dryer, and wherein the gasket is located between the rotatable drum and the bulkhead.
4. The hybrid vented tumble dryer of claim 3, wherein the gasket includes at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene.
5. The hybrid vented tumble dryer of claim 1, further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air.
6. The hybrid vented tumble dryer of claim 5, wherein the recirculation air filter is removably accessible from an inside of the drying chamber.
7. A hybrid vented tumble dryer comprising:
- a drying chamber including an inlet and an outlet, wherein process air moving through the drying chamber enters at the inlet and exits at the outlet;
- a heater configured to heat the process air entering the drying chamber;
- a process air fan configured to draw the process air through the drying chamber;
- an exhaust duct configured to exhaust a first portion of the process air from the drying chamber;
- a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater; and
- a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer and defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct, wherein the process air circuit is configured such that: the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater, and substantially the only fresh air which enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, after the heater and before the outlet of the drying chamber.
8. The hybrid vented tumble dryer of claim 7, further comprising at least one gasket, wherein substantially the only fresh air which enters the process air circuit enters directly into the drying chamber at the at least one gasket.
9. The hybrid vented tumble dryer of claim 8, wherein the drying chamber is a rotatable drum configured to rotate with respect to a bulkhead of the hybrid vented tumble dryer, and wherein the gasket is located between the rotatable drum and the bulkhead.
10. The hybrid vented tumble dryer of claim 9, wherein the gasket includes at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene.
11. The hybrid vented tumble dryer of claim 7, further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air.
12. The hybrid vented tumble dryer of claim 11, wherein the recirculation air filter is removably accessible from an inside of the drying chamber.
13. A hybrid vented tumble dryer comprising:
- a rotatable drum;
- a heater configured to heat process air entering the rotatable drum;
- a process air fan configured to draw the process air through the rotatable drum;
- an exhaust duct configured to exhaust a first portion of the process air from the rotatable drum;
- a recirculation duct configured to direct a second portion of the process air from the rotatable drum to the heater;
- a first bulkhead;
- a first drum seal gasket located between the rotatable drum and the first bulkhead in a non-airtight manner such that fresh air can enter the rotatable drum at the first drum seal gasket;
- a second bulkhead;
- a second drum seal gasket located between the rotatable drum and the second bulkhead in the non-airtight manner such that the fresh air can enter the rotatable drum at the second drum seal gasket; and
- a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer defined at least in part by the rotatable drum, the heater, the process air fan, the recirculation duct, the first bulkhead, and the second bulkhead,
- wherein the recirculation duct is in closed fluid communication with the heater.
14. The hybrid vented tumble dryer of claim 13, wherein substantially the only fresh air which enters the process air circuit is the fresh air entering the rotatable drum at the first drum seal gasket and the second drum seal gasket.
15. The hybrid vented tumble dryer of claim 13, wherein the fresh air enters the rotatable drum via a first airflow spacing provided between the first drum seal gasket and the first bulkhead, and via a second air airflow spacing provided between the second drum seal gasket and the second bulkhead.
16. The hybrid vented tumble dryer of claim 13, wherein the fresh air enters the rotatable drum via a first airflow spacing provided between the first drum seal gasket and the rotatable drum, and via a second air airflow spacing provided between the second drum seal gasket and the rotatable drum.
17. The hybrid vented tumble dryer of claim 13, wherein the first drum seal gasket and the second drum seal gasket are air-permeable, and wherein the fresh air enters the rotatable drum though the first drum seal gasket and the second drum seal gasket.
18. The hybrid vented tumble dryer of claim 13, wherein the first drum seal gasket and the second drum seal gasket include at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene.
19. The hybrid vented tumble dryer of claim 13, further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air.
20. The hybrid vented tumble dryer of claim 19, wherein the recirculation air filter is removably accessible at an access opening of the first bulkhead.
Type: Application
Filed: Aug 13, 2014
Publication Date: Feb 18, 2016
Applicant: ELECTROLUX APPLIANCES AKTIEBOLAG (Stockholm)
Inventors: Francesco Cavarretta (Pordenone), Alberto Bison (Pordenone), Maurizio Ugel (Porcia), Martha Angelica Flores Valdez (Porcia)
Application Number: 14/458,307