US3892104A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cryogenic freezer with variable speed gas control system
Assignee: Individual
•
Filing: 1973-09-20
•
Granted: 1975-07-01
•
Expires: 1993-09-20
Abstract
Abstract A cryogenic tunnel-type freezer is disclosed comprising a cryogenic liquid spray zone, a plurality of gaseous precooling zones having non-enclosed recirculation fans, and at least one enclosed, variable speed gas control blower for producing and varying the net forward flow of cold gas from the liquid spray zone, in which the gas is generated, toward the inlet end of the freezer through each of the precooling zones in countercurrent heat exchange with the product to be cooled and/or frozen; the speed of the gas control blower being directly responsive to changes in the amount of cryogenic liquid being supplied to the spray zone.
Inventors
- 👤 David J Klee
- 👤 Roger A Howells
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:40
CPC Classifications
F; F25; F25D; F25D3/00; F25D3/10; F25D3/11
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
143 words
A cryogenic freezer for freezing a product comprising an elongated insulated tunnel including a conveyor belt, a cryogenic liquid injection system and a plurality of gaseous cooling zones through which the product is passed in heat exchange relationship with the gas resulting from vaporization of the injected cyrogenic liquid, each of said plurality of cooling zones including recirculation fan means for recirculating said gas in contact with the product, gas control fan means for controlling the net forward flow of gas through said cooling zones, variable speed motor means for driving said gas control fan means at various speeds, and a control system operatively connected to said variable speed motor means and to said cryogenic liquid injection system for automatically varying the speed of said gas control fan means as a function of the amount of cryogenic liquid being injected into said freezer.
Claim 2
Dependent Claim
143 words
A cryogenic freezer for freezing a product comprising an elongated insulated tunnel including a conveyor belt, a cryogenic liquid injection system and a plurality of gaseous cooling zones through which the product is passed in heat exchange relationship with the gas resulting from vaporization of the injected cyrogenic liquid, each of said plurality of cooling zones including recirculation fan means for recirculating said gas in contact with the product, gas control fan means for controlling the net forward flow of gas through said cooling zones, variable speed motor means for driving said gas control fan means at various speeds, and a control system operatively connected to said variable speed motor means and to said cryogenic liquid injection system for automatically varying the speed of said gas control fan means as a function of the amount of cryogenic liquid being injected into said freezer.
Claim 3
Dependent Claim
40 words
The cryogenic freezer as claimed in claim 1 wherein said gas control fan means is located along the length of the tunnel at a position at which the temperature of the gas in the tunnel is colder than minus 50*F.
Claim 4
Dependent Claim
42 words
The cryogenic freezer as claimed in claim 1 further including manual electrical control means for manually varying the speed of said gas control fan means, and mode selector switch means for operating said control system in either an automatic or manual mode.
Claim 5
Dependent Claim
39 words
The cryogenic freezer as claimed in claim 1 wherein said cryogenic liquid injection system includes injection means for injecting cryogenic liquid into at least one of said gaseous cooling zones for vaporization in contact with the gas recirculating therein.
Claim 6
Dependent Claim
26 words
A cryogenic freezer as claimed in claim 1 including an intermediate drive unit connected between said variable speed motor means and said gas control fan means.
Claim 7
Dependent Claim
40 words
The cryogenic freezer as claimed in claim 1 wherein said control system includes pressure sensing means connected to said cryogenic liquid injection system, and transducer means for converting the sensed pressure of the cryogenic liquid into an electrical control signal.
Claim 8
Dependent Claim
29 words
The cryogenic feeezer as claimed in claim 6 further including pressure smoothing means connected between said cryogenic liquid injection system and said transducer means for suppressing spurious pressure fluctuations.
Claim 9
Dependent Claim
46 words
The cryogenic freezer as claimed in claim 1 wherein said gas control fan means comprise a blower mounted inside said insulated tunnel including an outlet positioned so as to discharge the gas from said blower in a direction toward the product inlet end of the freezer.
Claim 10
Dependent Claim
30 words
The cryogenic freezer as claimed in claim 8 further including a discharge duct connected to said blower outlet for directing the gas toward the product inlet end of the freezer.
Claim 11
Dependent Claim
38 words
The cryogenic freezer as claimed in claim 1 wherein said variable speed motor comprises a D.C. motor, and said control system includes a D.C. power source having a variable D.C. output connected to said variable speed D.C. motor.
Claim 12
Dependent Claim
37 words
The cryogenic freezer as claimed in claim 10 including a maximum speed limiting potentiometer connected to said D.C. power supply and having at least three turns for accurately setting the maximum RPM of the variAble speed motor.
Claim 13
Dependent Claim
59 words
The cryogenic freezer as claimed in claim 1 wherein said cryogenic liquid injection system includes spray header means for directly contacting the product with cryogenic liquid and thereby vaporizing the liquid to a gas, and wherein said plurality of gaseous cooling zones comprise precooling zones positioned between the product inlet end of the tunnel and said spray header means.
Claim 14
Dependent Claim
23 words
The cryogenic freezer as claimed in claim 12 wherein said gas control fan means is located between two of said gaseous precooling zones.
References Cited (Backward Citations)
US2904254A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-30 | 1978-12-30 | 1979-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-30 | 1982-12-30 | 1983-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-30 | 1986-12-30 | 1987-07-01 | $7700.00 | Window Closed / Lapsed |