Patent Application
20080314260
1. Field of the Invention
The present invention is broadly concerned with food treatment apparatus and systems such as smokehouses and chillers, characterized by forced-air treatment of food products with damper control and modulation of the forced-air currents. More particularly, it is concerned with such apparatus and systems including at least one dual damper assembly made up of first and second dampers rotated in a desired phase relationship, with a brake assembly operably coupled with at least one of the dampers in order to lessen damper flutter and the tendency of the dampers to operate out of phase.
2. Description of the Prior Art
Conventional smokehouses are designed to uniformly cook and process food products such as hot dogs, sausages, and hams. In such devices, the food to be processed is passed through a cooking/smoking zone while heated, smoke-laden, pressurized air currents are passed through the zone. It is important to establish and maintain uniform temperatures throughout the cooking/smoking zone in such operations. Otherwise, overheating of portions of the food product can occur before other portions thereof are brought to proper finishing temperature, resulting in product losses.
In an effort to achieve uniform cooking/smoking conditions, many existing smokehouses have a fan cabinet to generate pressurized air currents, with spaced apart, separate ducts leading to the cooking/smoking zone. A dual damper system is used in these devices, with an individual, rotatable damper located within each duct. The dual dampers are driven in a predetermined phase relationship, typically 90° out of phase, so that when one duct is fully closed, the other is fully open. The purpose of such an arrangement is to establish and maintain an optimum “break-point,” defined as the constantly moving point of turbulence where opposed air currents collide. As the alternating dampers rotate, one current of air increases in volume and velocity as the associated damper rotates to the full open position, while the opposite current of air decreases in volume and velocity as the associated damper moves to the full closed position. As can be appreciated, maintaining the predetermined phase orientation of the damper blades is critical for the creation and maintenance of the most effective break-point. If this phase orientation is lost, heat transfer efficiency to the food products is reduced, thus creating inconsistent cooking throughout the cooking/smoking zone. Further, cook times will be extended thus reducing the productivity of the equipment. A principal problem in this regard is the tendency of the dampers to “flutter” during operation. Flutter is created during damper rotation under the influence of pressurized air currents, and results in rapid, reversing rotational movement of the damper blades which compromises the desired relative blade orientation.
In many alternating damper systems the dampers are driven by a chain drive arrangement between the drive motor and first damper, and between the spaced apart damper rods. The use of two chains in such designs creates damper control break-point problems. First, the user must constantly maintain chain tightness in each chain in order to minimize damper flutter. Moreover, chains inherently have some built-in degree of looseness, which further contributes to the flutter problem. In other cases the dampers in dual damper systems are driven by rigid drive lines. This assists in maintaining damper control, but even in such situations flutter can be a problem.
These same considerations apply in other types of forced-air food treatment systems, e.g., cookers or chillers.
A number of prior art patents describe smokehouses and related equipment making use of dual damper systems. See e.g., U.S. Pat. Nos. 2,625,095; 2,505,973; 2,640,414; 3,721,177; 4,307,286; and DE 2,342,949. Other references of background interest include U.S. Pat. Nos. 3,199,436; 2,832,278; 6,644,957; 6,537,146; 6,503,140; 4,263,842; 4,205,783; 4,185,770; 3,897,773; 3,805,884; 2,746,374; 2,856,131; 4,645,137; 2,693,917; and JP 4-337,133.
The present invention overcomes the problems outlined above and provides dual damper assemblies designed for use in food treatment apparatus and systems such as smokehouses and chillers. Broadly speaking, the dual damper assemblies of the invention comprise first and second dampers each including an elongated, axially rotatable rod and a damper body secured to the rod for rotation therewith. A drive assembly is operably coupled with the first and second dampers for rotation thereof in a desired relative orientation, and a brake assembly is operably coupled with at least one of the dampers in order to lessen damper flutter tending to alter the desired relative damper orientation.
In preferred forms, the drive assembly includes a drive motor operably secured to the rod of the first damper, with a drive arrangement extending between and coupling the first and second damper rods. This drive arrangement may be in the form of a rigid drive rod, a drive chain, or any other suitable drive mechanism. The brake assembly comprises a rotatable disc element secured to one of the damper rods and rotatable therewith, and a caliper assembly engageable with the disc to brake the one damper rod. The caliper assembly typically includes a pair of spring-biased brake pads on opposite sides of and engageable with the disc.
The respective dampers can be oriented in any desired phase relationship, but most often a 90° or perpendicular relationship is established. This damper orientation is effectively maintained with a minimum of flutter owing to the presence of the brake assembly.
The present invention also pertains to food treatment apparatus and systems including the dual damper assemblies. Such apparatus commonly has a housing including walls defining a region for receiving food product to be treated, and first and second spaced apart air passageways in communication with the treatment region. A fan is also provided for generating air currents, and the dual damper assembly is arranged so that the dampers are respectively located within the individual passageways for air control.
Turning now to the drawings, a smokehouse 20 is illustrated in
The overall air handling system 26 also includes a dual damper assembly 44 (see
In more detail, the dual damper assembly 44 includes, in addition to first and second dampers 46 and 48, a drive assembly 50 operably coupled with the dampers 46, 48 for rotation thereof in the desired relative orientation, and a brake assembly 52 operably coupled with the damper 48 in order to lessen damper flutter which would otherwise tend to alter the desired relative orientation of the dampers 46, 48 during rotation.
Each of the dampers 46 and 48 are substantially identical and include an elongated, central, axially rotatable rod 54a, 54b as well as a plate-like, substantially planar damper body 56a, 56b secured to the associated rod for rotation therewith. The rods 54a, 54b each include an extension 58a, 58b as best seen in
The drive assembly 50 includes a motor 66 coupled with extension 58a of rod 54a in order to drive damper 46, as well as a cross-drive assembly 68 for driving the opposed damper 48. The cross-drive assembly 68 includes right-angle gear boxes 70, 72 operatively coupled with the damper rods 54a, 54b, as well as drive line 74 interconnecting the gear boxes 70, 72. It will be appreciated that a chain drive could be used to interconnect the dampers 46, 48, in lieu of the assembly 68. It will be appreciated that actuation of motor 66 serves to rotate both dampers 46 and 48 during operation of smokehouse 20; typically, the dampers are rotated at a relatively low speed of 1-2 rpm. Furthermore, it will be observed that the dampers 46, 48 are initially positioned in the desired 90° out of phase relationship illustrated in
The brake assembly 52 generally includes a brake disc 76 operably keyed to extension 58b, as well as a caliper assembly 78 supported on a bracket 80, the latter secured to the upper end of the plate 62 adjacent with damper 48. The disc 76 includes a pair of opposed, flattened braking surfaces 82, 84 as well as an outwardly extending shoulder 86 extending around approximately ½ of the periphery of the disc 76.
Caliper assembly 78 includes a pair of opposed, apertured mounting blocks 88 and 90 which depend from a cross-block 92 secured to the underside of bracket 80. The blocks 88, 90 in turn support a pair of brake pads 94, 96 oriented to engage the disc braking surfaces 82, 84. Each of the pads 94, 96 includes a somewhat L-shaped metallic support plate 98, 100 which also are attached to apertured pad mounts 102, 104. In order to support the brake pads 94, 96 and associated structure, a pair of spaced apart guide pins 106 (see
It will also be seen (
The brake assembly 52 operably coupled with damper 48 serves to effectively minimize the extent of any damper flutter which would otherwise tend to alter the desired relative orientation of the damper bodies 56a, 56b during rotation thereof. This is accomplished by the biased engagement between the brake pads 94, 96 and the braking surfaces 82, 84 of disc 76, adjustable by the means of the tension bolt assemblies 116, 118. In this fashion the optimum break-point is established and maintained within the smokehouse 20.
In the operation of smokehouse 20, the fan 30 and steam coils 42 are continuously operated so as to direct heated air/smoke currents through the passageways 34, 36 for cooking/smoking of food products within region 24. At the same time, the dual damper assembly 44 is operated to slowly rotate the dampers 46, 48 within the passageways 34, 36. The perpendicular out-of-phase relationship between the respective dampers 46, 48 serves to alternate the air currents passing through the passageways 34, 36, i.e., the currents through one passageway increase in volume and velocity as the associated damper moves to the full-open position, and the currents through the opposite passageway diminish in volume and velocity as the associated damper moves to the full-closed position. This is the preferred relationship for proper break-point maintenance. The brake assembly 52 effectively limits any flutter within the dual damper assembly 44, so that the phase relationship between the dampers is maintained. Additionally, the caliper assembly 78 is mounted to float along the axis of the damper 48, thereby accommodating any linear movements due to thermal expansion and contraction. Accordingly, the brake assembly 52 properly functions regardless of the temperatures encountered during system operation. The proximity sensor 130 senses the presence or absence of shoulder 86 during rotation of disc 76. The sensor 130 is coupled with the control system for the smokehouse 20 and is designed to “look for” the shoulder signal over a given time period. If the signal is not received or remains present for a time period longer than a predetermined programmed time, an alarm (not shown) will sound, indicating that damper rotation has ceased and that service is required.
While the dual damper assembly 44 has been illustrated and described in the context of a smokehouse, the invention is not so limited. For example, the same dual damper assembly could be used in other types of heated-air cooking systems or in chillers. Accordingly, the present disclosure should be considered exemplary in nature and not limiting.
