Thermal Immersion Circulator

Abstract

A thermal immersion circulator may include a heater comprising a hollow cylindrical body having an inlet opening at a first end thereof and an outlet opening in a sidewall thereof. The heater may include a flexible circuit board having a plurality of resistive strips controlled by control electronics, such as a TRIAC, which may be water-cooled. A thermal immersion circulator including the heater may be used in a scientific laboratory or for sous vide cooking of food.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 201680073843.1, with the application date of October 14, 2016 and the invention name of "Thermal Immersion Circulator", which is based on international application PCT / US2016 / 057205 and claims priority to U.S. patent application 62 / 242,864 filed on October 16, 2015, the entire contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] The present disclosure generally relates to an electric thermal immersion circulator for heating various fluids. Background Art

[0003] Thermal immersion circulators can be used to circulate and heat various fluids, for example, to maintain a body of fluid at a precise and stable temperature. A thermal immersion circulator may include a pump or other mechanism for circulating the fluid, as well as a heating element for heating the fluid. Thermal immersion circulators are used in scientific and other laboratories, as well as in kitchens, particularly for sous vide cooking. Summary of the Invention

[0004] A thermal immersion circulator can be summarized as comprising: a heater, the heater comprising: a body having a tubular sidewall, a first end, a second end spaced apart from the first end by a length of the body, the tubular sidewall forming a fluid flow passage at least partially therethrough, the body having an inlet at least proximate the first end and an outlet in the tubular sidewall, the inlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body, at least a portion of the outlet being spaced apart relative to at least a portion of the inlet relative to the second end, the outlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body; a heating element physically coupled to and at least partially wrapped around at least a portion of the tubular sidewall of the body; and a switch electrically coupled to control the heating element, the switch being physically and thermally coupled to the tubular sidewall of the body; and a housing sized and dimensioned to receive at least a portion of the heater.

[0005] The entire outlet is closer to the second end than the entire inlet. The entire heating element is located between the inlet and the outlet. The tubular sidewall forms an inlet at the first end. The tubular sidewall has a central axis, the inlet is radially arranged about the central axis, and the outlet extends parallel to and radially spaced from the central axis of the tubular sidewall. The entire heating element may be located between the entire inlet and the entire outlet. The outlet is a rectangular slot in the tubular sidewall. The tubular sidewall may have an upper portion and a lower portion, the upper portion having a flat surface on which the switch is physically and thermally mounted. The lower portion of the tubular sidewall is cylindrical. The heating element may be wound at an angle around at least three-quarters of the circumference of the tubular sidewall. The entire heating element may be located between the entire inlet and the entire outlet. The switch is a packaged TRIAC.

[0006] The thermal immersion circulator may further include a motor mounted at least proximate the second end of the body. The thermal immersion circulator may further include an impeller disposed within the tubular body. The thermal immersion circulator may further include a shaft physically coupling the motor to the impeller. The impeller may be positioned closer to the inlet than the outlet. The thermal immersion circulator may further include a support member comprising a boss for receiving a strain relief for a power cord and a recess for receiving a spring clip, wherein the support member, the boss, and the recess are formed from a single, unitary piece of material.

[0007] The heater of a thermal immersion circulator can be summarized as including a body having a tubular sidewall, a first end, a second end spaced apart from the first end by the length of the tubular body, the tubular sidewall forming a fluid flow passage at least partially therethrough, the body having an inlet at least proximate the first end and an outlet in the tubular sidewall, the inlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body, at least a portion of the outlet spaced apart relative to at least a portion of the inlet relative to the second end, the outlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body; a heating element physically coupled to and at least partially wrapped around at least a portion of the tubular sidewall of the body, the entire heating element being located between the inlet and the outlet; and a switch electrically coupled to control the heating element and physically and thermally coupled to the tubular sidewall of the body.

[0008] The entire outlet can be spaced relatively closer to the second end than the entire inlet. The tubular sidewall can define an inlet at the first end. The tubular sidewall has a central axis, the inlet is radially disposed about the central axis, and the outlet extends parallel to and radially spaced from the central axis of the tubular sidewall. The outlet can be a rectangular slot in the tubular sidewall. The tubular sidewall can have an upper portion and a lower portion, the upper portion having a flat surface on which the switch is physically and thermally mounted. The lower portion of the tubular sidewall can be cylindrical and have a circumference, and the heating element can be wound at an angle about at least three-quarters of the circumference of the tubular sidewall.

[0009] A thermal immersion circulator can be summarized as comprising: a heater comprising: a body having a tubular sidewall, a first end, a second end spaced apart from the first end by a length of the body, the tubular sidewall forming a fluid flow passage at least partially therethrough, the body having an inlet at least proximate the first end and an outlet at least proximate the second end, the inlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body, the outlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body; a heating element physically coupled to and at least partially wrapped around at least a portion of the tubular sidewall of the body; and a switch electrically coupled to control the heating element and physically and thermally coupled to the tubular sidewall of the body; and a housing sized and dimensioned to receive at least a portion of the heater, the housing comprising the tubular sidewall and an opening formed in the tubular sidewall of the housing, the opening being in fluid communication with the outlet of the body.

[0010] A heater for a thermal immersion circulator can be summarized as comprising: a body having a tubular sidewall, a first end, a second end spaced apart from the first end by the length of the tubular body, the tubular sidewall defining a fluid flow passage at least partially therethrough, the body having an inlet at least proximate the first end and an outlet in the tubular sidewall, the inlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body, at least a portion of the outlet spaced apart from at least a portion of the inlet relative to the second end, the outlet providing fluid communication between the fluid flow passage in the interior of the body and the exterior of the body; a heating element physically coupled to and at least partially wrapped around at least a portion of the tubular sidewall of the body, the entire heating element being located between the inlet and the outlet; and a switch electrically coupled to control the heating element and physically and thermally coupled to the body. The thermal immersion circulator can be summarized as comprising: a heater; an inlet having a longitudinal central axis and an inlet port curved at least partially about the longitudinal central axis, the inlet having a height; and a power cord electrically coupled to the heater, the power cord having a diameter less than the height of the inlet so as to fit snugly within the inlet and engage the inlet with an interference fit. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the drawings, like reference numerals denote similar elements or activities. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some elements may be arbitrarily enlarged and positioned to improve drawing legibility. Furthermore, the particular shapes of drawn elements are not necessarily intended to convey any information about the actual shape of a particular element and may have been individually selected for ease of identification in the drawings.

[0012] Figure 1 A thermal immersion circulator is shown positioned in a pot, according to at least one illustrated embodiment.

[0013] Figure 2 According to at least one of the illustrated embodiments Figure 1 A perspective view of a three-dimensional rendering of a thermal immersion circulator, wherein the outer shell of the thermal immersion circulator is illustrated as transparent to show the internal components of the thermal immersion circulator.

[0014] Figure 3 According to at least one illustrated embodiment Figure 2 Cross-section of a thermal immersion circulator is shown.

[0015] Figure 4 According to at least one illustrated embodiment Figure 2 Exploded view of a Thermal Immersion Circulator shown.

[0016] Figure 5 is a three-dimensional rendering in perspective view of a heater for a thermal immersion circulator, according to at least one illustrated embodiment.

[0017] Figure 6 According to at least one of the illustrated embodiments Figure 5 Rear view of the heater.

[0018] Figure 7 According to at least one of the illustrated embodiments Figure 5 Left side view of the heater.

[0019] Figure 8 According to at least one of the illustrated embodiments Figure 5 Front view of the heater.

[0020] Figure 9 is along the lines of at least one illustrated embodiment Figure 6 Intercept the line AA in Figure 5 Cross-sectional view of the heater.

[0021] Figure 10 is along the lines of at least one illustrated embodiment Figure 6 The line BB in the Figure 5 Cross-sectional view of the heater.

[0022] Figure 11 According to at least one of the illustrated embodiments Figure 5 A plan view of the flexible circuit board in the heater.

[0023] Figure 12 According to at least one of the illustrated embodiments Figure 5 A rear view of the heater, showing the Figure 11 flexible circuit boards.

[0024] Figure 13 According to at least one of the illustrated embodiments Figure 5 A left side view of the heater, showing Figure 11 Flexible circuit board.

[0025] Figure 14 According to at least one of the illustrated embodiments Figure 5 A three-dimensional rendering of a perspective view of a heater showing other elements coupled to the heater.

[0026] Figure 15 is a method for use with Figure 5 A 3D rendering of a perspective view of an impeller used with a heater.

[0027] Figure 16 is an exploded view of another thermal immersion circulator according to at least one illustrated embodiment.

[0028] Figure 17 According to at least one of the illustrated embodiments Figure 16 A 3D rendering of a perspective view of the thermal immersion circulator's engine and electronics.

[0029] Figure 18 According to at least one of the illustrated embodiments Figure 16 A 3D rendering of a thermal immersion circulator engine in perspective view.

[0030] Figure 19 According to at least one of the illustrated embodiments Figure 16 A plan view of the flexible circuit board of a thermal immersion circulator heater.

[0031] Figure 20 According to at least one of the illustrated embodiments Figure 16 Side view of a thermal immersion circulator.

[0032] Figure 21 According to at least one of the illustrated embodiments Figure 16 A cross-sectional side view of the components of a thermal immersion circulator.

[0033] Figure 22 A thermal immersion circulator is shown positioned in a pot, according to at least one illustrated embodiment. DETAILED DESCRIPTION

[0034] In the following description, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments can be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with the technology are not shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0035] Throughout the following description and claims, the word "comprising" is used synonymously with "including" and is inclusive or open-ended (ie, does not exclude additional, unrecited elements or methodological acts) unless the context requires otherwise.

[0036] Throughout this specification, references to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0037] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should also be noted that the term "or" is generally used in its broadest sense, that is, to mean "and / or" unless the context clearly dictates otherwise.

[0038] The titles and abstracts of the disclosure provided herein are for convenience only and do not limit the scope or meaning of the embodiments.

[0039] As used herein, the terms "above" and "below," "top" and "bottom," "vertical" and "horizontal," and other similar terms refer solely to the relative positions of components, as shown in the figures, and convey their ordinary meanings within the context of the figures. In some embodiments, these terms may carry their ordinary meanings within the context of actual implementations, e.g., gravity pulling an item from a first position above a second position to a second position. However, the use of these terms alone is not intended to convey that, if a first component is described as being above another component within the context of a figure, the first component must be above the other component in an actual implementation.

[0040] As used herein, "coupled," "connected," and other similar terms, when used alone, mean a physical coupling or physical connection. Components that are "coupled" or "connected" electrically or otherwise are described as such.

[0041] Figure 1 A thermal immersion circulator 10 is shown positioned within a container, vessel, or pot 12. The pot 12 may contain water or another fluid for cooking food, and the thermal immersion circulator 10 may be used to heat, maintain the temperature of, or circulate the fluid within the pot. The thermal immersion circulator 10 may be used for sous vide cooking. Depending on the size of the pot 12, the depth of the fluid within the pot 12, and the like, the thermal immersion circulator 10 may be positioned at the bottom of the pot 12 (e.g., Figure 22) stands upright in the pot, or can be clipped, clamped, or otherwise attached to the edge or side of pot 12. Thermal immersion circulator 10 can include a waterproof housing 16 that protects the circuitry therein so that thermal immersion circulator 10 can be safely submerged in water. Housing 16 can be opaque.

[0042] Figure 2 The thermal immersion circulator 10 is shown with the housing 16 shown as transparent to illustrate the various internal components of the thermal immersion circulator 10. The thermal immersion circulator 10 may include a lower inlet assembly 14 having a flat bottom surface on which the thermal immersion circulator 10 may stand, such as in a pot 12. In some embodiments, the flat bottom surface may include magnets (e.g., similar to Figure 21 The magnet 308 shown in FIG and described further below helps retain the thermal immersion circulator 10 within the pot 12. The lower inlet assembly 14 can have a peripheral radial opening through which fluid can be drawn into the interior of the thermal immersion circulator 10 or through which fluid can be exhausted from the interior of the thermal immersion circulator 10.

[0043] The thermal immersion circulator 10 may also include a heater 100, which will be described in more detail below. The bottom end of the heater 100 may be coupled to the lower inlet assembly 14, such that the internal conduits or channels through the heater 100 are in fluid communication with the peripheral opening of the inlet assembly 14. The housing 16 may include an opening 18 formed in a sidewall of the housing 16, through which fluid may be drawn into the interior of the thermal immersion circulator 10 or exhausted from the interior of the thermal immersion circulator 10. The side surfaces of the heater 100 may be coupled to the opening 18, such that the internal conduits through the heater 100 are in fluid communication with the opening 18, for example, through openings or slots 126 in the sides of the heater 100 and channels 180 through the spacer 178, as described in more detail below. In another alternative embodiment, the top of the heater 100 may be coupled to the opening 18, such that the internal conduits through the heater 100 are in fluid communication with the opening 18, for example, through an opening in the top of the heater 100.

[0044] The thermal immersion circulator 10 may include upper and lower isolation grilles 20 that can separate the thermal immersion circulator 10 into different thermal zones or chambers. For example, the lower isolation grille 20 can separate the heater 100 from other electrical components of the thermal immersion circulator 10 disposed above the lower isolation grille 20, such as a high-temperature transformer 22 and a PCBA (printed circuit board assembly) 24 mounted within an electronics module housing 26. The thermal immersion circulator 10 also includes a top cover assembly 28 to cover the top end of the housing 16. The thermal immersion circulator 10 may also include a removable clip 30 to clip the thermal immersion circulator 10 to a side of the pot 12 so that the thermal immersion circulator 10 is mounted to a side of the pot 12 so that a power cord 32 is not submerged. The power cord 32 can be used to plug the thermal immersion circulator 10 into a standard wall outlet to draw power from the electrical grid. The removable clip 30 can be used to clamp the thermal immersion circulator 10 to pots of various sizes and shapes, such as pot sides having various radii of curvature.

[0045] Figure 3 The thermal immersion circulator 10 is shown in cross-section. A thermal isolation grid 20 divides the interior of the thermal immersion circulator 10 into three distinct thermal zones: first, an upper PCBA zone 34, which can operate at a temperature of 70°C or thereabouts; second, a lower PCBA zone 36, which can operate at a temperature of 100°C or thereabouts; and third, a motor zone 38, which can operate at a temperature of 100°C or thereabouts. For example, the lower inlet assembly 14 can be removed from the rest of the thermal immersion circulator 10 to facilitate cleaning of the heater 100. Similarly, for example, the top cover assembly 28 can be removed from the rest of the thermal immersion circulator 10 to facilitate access and repair of the electrical components housed therein.

[0046] Figure 4 The thermal immersion circulator 10 is shown in an exploded view and illustrates a method of assembling the thermal immersion circulator 10. For example, the method of assembling the thermal immersion circulator 10 may include, but not necessarily in the following order: inserting the heater 100 into the housing 16, then securing the heater 100 within the housing 16 using the coupling nut 40, inserting the electronics module including the electronics module housing 26 into the housing 16, then connecting the power cord 32 to the electronics module through the housing 16, then connecting and securing the top cover assembly 28 to the housing 16, then connecting the lower inlet assembly 14 to the housing 16, the heater 100, and the coupling nut 40, and then attaching the clip 30 to the housing 16.

[0047] Figure 5A heater 100 is shown that can be used in a thermal immersion circulator, such as the thermal immersion circulator 10. The heater 100 includes a hollow, substantially cylindrical body 102 having tubular sidewalls and an annular cross-sectional shape, a radial flange, foot, or ridge 104 coupled to a bottom end portion of the body 102, and a baffle, barrier, or spacer 106 coupled to a top end portion of the body 102. In alternative embodiments, the body 102 can have a generally circular, oval, rectangular, square, triangular, or other suitable cross-sectional shape. The body 102, flange 104, and baffle 106 can be made from a single, unitary piece of material, or they can be made from different materials coupled to one another using any of a variety of known techniques. In other embodiments, the heater 100 can be manufactured without the flange 104.

[0048] The body 102, flange 104, and baffle 106 can be made of any suitable material, such as any suitable metal (e.g., polished stainless steel, copper, or aluminum), plastic (e.g., thermosetting plastic), ceramic, porcelain, etc., and these components can be made of the same material or different materials. The body 102, flange 104, and baffle 106 can also be coated with a non-stick material. The material can be electrically conductive or non-conductive, thermally conductive or non-conductive, and have sufficient strength and heat resistance to provide rigidity and structure to the heater 100 at temperatures within the expected operating range of the heater 100. Using a metal material such as stainless steel provides the heater 100 with a very smooth surface, allowing the heater 100 to be easily and quickly cleaned.

[0049] The body 102 includes a hollow cylindrical bottom 108 having an inner surface 130 and an outer surface 132 (see FIG. Figure 10 ), each of which has a circular cross-sectional shape. The body 102 also includes a top 110 that is substantially cylindrical and has a first left flat wall 112 and a second right flat wall 114. Across the top 110 of the body 102, the left side wall 112 is disposed opposite the right side wall 114 such that the left side wall 112 is parallel to the right side wall 114. The top 110 is hollow and has an inner surface 134 and an outer surface 136 (see FIG. Figure 9 ), the inner surface 134 and the outer surface 136 have a circular cross-sectional shape truncated by the left side wall 112 and the right side wall 114.

[0050] Such as stud 116 (in Figure 5A pair of protrusions (only one of which is visible) can be coupled to and / or extend from the top 110 of the body. For example, a first stud 116 can extend radially away from and perpendicular to the left side wall 112, and a second stud 116 can extend radially away from and perpendicular to the right side wall 114. The studs 116 can include solid cylindrical protrusions with threads on an outer surface of the protrusion. In addition, a flexible circuit board 122 is coupled to the outer surfaces of the body 102, including an outer surface 132 coupled to the bottom 108 and an outer surface 136 coupled to the top 110 of the body 102. As described in more detail below, the flexible circuit board 122 is a thick film flexible circuit board 122, but other embodiments may use a thin film flexible circuit board, a thin film resistive heater, a thick film resistive heater, a wire wound heater, a flexible polyamide, or other similar technologies instead.

[0051] The radial flange 104 has an annular shape, and the outer diameter of the flange 104 is larger than the outer diameter of the body 102. In some embodiments, the inner diameter of the flange 104 can match the inner diameter of the body 102, so that the flange 104 can be coupled to the bottom end of the body 102, leaving the inner portion 128 of the body 102 (see Figure 9-10 ) is flush with the inner surface of the flange 104. In other embodiments, the inner diameter of the flange 104 can match the outer diameter of the body 102 so that the flange 104 can be coupled to the outer surface 132 of the bottom 108 of the body 102 at the bottom end of the body 102. The flange 104 can be formed from a single flat sheet of material, such as by cutting a circular opening in a flat circular material. Therefore, the cross-sectional shape of the flange 104 along a vertical plane is rectangular. The flange 104 can form part of a seal between the heater 100 and another component of the thermal immersion circulator of which the heater 100 is a part. In some embodiments, the body 102 and the radial flange 104 can be made integrally, such as in a single molding process, such as in a single metal injection molding process.

[0052] The diaphragm 106 has a truncated circular shape that matches the truncated circular shape of the top portion 110 of the main body 102. In some embodiments, the shape of the outer or peripheral surface of the diaphragm 106 can match the shape of the outer surface 136 of the top portion 110 of the main body 102, so that the diaphragm 106 can be coupled to the top end of the top portion 110 of the main body 102. In other embodiments, the shape of the outer or peripheral surface of the diaphragm 106 can match the shape of the inner surface 134 of the top portion 110 of the main body 102, so that the diaphragm 106 can be coupled to the inner surface 134 of the top portion 110 of the main body 102 at the top end of the main body 102. In some embodiments, the main body 102 and the diaphragm 106 can be integrally formed, for example, in a single molding process, such as a single metal injection molding process. In other embodiments, the diaphragm 106 can be an integral part of the engine of the thermal immersion circulator 10, for example, as the bottom of the engine housing.

[0053] The partition 106 may include three holes extending therethrough, for example, a relatively large hole 118 located at the center of the partition 106 and two relatively smaller holes 120 located off-center on the partition 106. The partition 106 may separate the hollow interior 128 of the heater 100 from the exterior of the heater 100 above the heater 100. The peripheral surface of the central hole 118 may be smooth and, as further described below, the central hole 118 may be configured to allow the rotor or drive shaft 190 (see FIG. 1 ) to be rotated. Figure 3 ) from the outside through the partition 106 into the interior 128 of the heater 100. In this way, the drive shaft 190 can be installed in a sleeve or bearing, such as a rolling bearing, which can be installed in the center hole 118.

[0054] As will be further described below, the eccentric hole 120 can be configured to allow the screw 192 (see Figure 3 ) or other fasteners (e.g., bolts, nails, etc.) are threaded from the outside through the bulkhead 106 and into the interior 128 of the heater 100 to couple the engine to the top of the heater 100. For example, the outer peripheral surface of the hole 120 may be threaded, or the bottom surface of the bulkhead 106 ( Figure 5 The bulkhead 106 (not visible in the figures) may have countersunk holes around each hole 120 to receive the head of a screw 192 to be screwed through the bulkhead 106 into the motor at the top of the heater 100. The holes 118 and 120 may be positioned so that a line extending through the center of each hole 118 and 120 is parallel to the left side wall 112 and the right side wall 114. In some embodiments, such as if the motor is coupled to the top of the heater 100 using an adhesive, the holes 120 are not used and the bulkhead 106 may include a single hole 118 extending therethrough.

[0055] Figure 6 、 78 are a rear view, a left side view, and a front view of the heater 100, respectively. Figure 6 The transition 124 between the left and right side walls 112 , 114 of the bottom 108 and top 110 of the body 102 is shown as being curved. Figure 7 The studs 116 are shown extending from the left and right side walls 112 , 114 from locations within the bottom half of the side wall 112 or 114 and from locations within the front half of the side wall 112 or 114 . Figure 8 An oblong hole or slot 126 is shown extending through the front portion of the tubular sidewall of the body 102 , ie, through the curved front portion of the tubular sidewall of the cylindrical body 102 .

[0056] Slot 126 is located at the front of body 102 such that slot 126 is equidistant from left and right side walls 112, 114, and such that the centers of apertures 118, 120, and slot 126 lie in a plane parallel to left and right side walls 112, 114, with body 102 symmetrical about this plane. Slot 126 has a relatively long vertical axis and a relatively short horizontal axis, and thus may be referred to as a vertical slot 126. In alternative embodiments, slot 126 may have a relatively long horizontal axis and a relatively short vertical axis and may be referred to as a horizontal or radial slot 126. Vertical slot 126 spans a portion of top 110 of body 102 and a portion of bottom 108 of body 102. Vertical slot 126 extends above and below a curved transition portion 124 between side walls 112, 114 of bottom 108 and top 110 of body 102. The vertical slot 126 is positioned closer to the top end of the body 102 than to the bottom end thereof.

[0057] The top ends of the vertical grooves 126 can be coplanar with the bottom surface of the baffle 106 or the top surface of the interior 128 of the body 102, or can extend above the bottom surface of the baffle 106 or the top surface of the interior 128 of the body 102. Thus, any gas that enters or forms within the interior 128 of the body 102 can flow out of the interior 128 of the body 102 and out of the circulator 10, thereby reducing the harmful effects of air or other gas accumulation within the body interior 128. In some embodiments, the bottom surface of the baffle 106 can be inclined upward toward the vertical grooves 126, so that bubbles that enter or form within the interior 128 naturally flow toward the vertical grooves 126 to exit the circulator 10. In some embodiments, the bottom surface of the baffle can have a spiral shape, so that bubbles that enter or form within the interior 128 naturally flow upward along the spiral toward the vertical grooves 126 to exit the circulator 10.

[0058] When heater 100 is in use, the opening in the bottom of body 102 can serve as the inlet of heater 100, slot 126 can serve as the outlet of heater 100, and interior 128 can serve as a conduit, channel, or passageway in fluid communication with the inlet and outlet. As described further below, thick-film flexible circuit board 122 can be wrapped around the outer surface of body 102 between the inlet and outlet, and thus can be wrapped around a conduit that fluidly couples the inlet to the outlet. Flexible circuit board 122 can separate the inlet and outlet and can be positioned to heat fluid passing between the inlet and outlet. The fluid flow path through heater 100 can extend from the inlet through the conduit of flexible circuit board 122 to the outlet. Flexible circuit board 122 can be separated from the fluid passing through interior 128 of body 102 by a distance corresponding to the thickness of the tubular sidewall of body 102, which can be 0.5 mm, 1.0 mm, 1.5 mm, 2 mm, 2.5 mm, between 0.1 mm and 5 mm, or between 0.5 mm and 2.5 mm.

[0059] Figure 9 and 10 The edges are shown Figure 6 1 is a cross-sectional view of the heater 100 taken along lines AA and BB. Figure 11 The flexible circuit board 122 is shown in more detail. Figure 11 As shown, the flexible circuit board 122 can be a flexible thick film flexible circuit board 122 that includes multiple thick film layers. For example, the flexible circuit board 122 includes an insulating base layer 138 of an electrically insulating material. The insulating base layer 138 can electrically isolate the body 102 of the heater 100 from the conductive components (e.g., traces or resistive strips) of the flexible circuit board 122 and any control electronics coupled thereto, so that the body 102 can be made of any suitable conductive or electrically insulating material without interfering with the operation of the flexible circuit board 122.

[0060] The flexible circuit board 122 also includes a plurality (three in the illustrated embodiment) of first resistive strips 140 that together form a first heating element 144 located on a bottom portion of the base layer 138, and a plurality (three in the illustrated embodiment) of second resistive strips 142 that together form a second heating element 146 located above the first heating element 144 on the base layer 138. Each of the first resistive strips 140 and the second resistive strips 142 may comprise a thick film strip formed on the base layer 138 and may be made of any suitable resistive material. For example, the first and second resistive strips 140 and 142 may be made of an FeCrAl alloy, such as that sold under the trade name PTFE. For example, a resistive paste can be applied to base layer 138, and the width and thickness of the paste can be carefully controlled to provide a well-defined resistance for each resistive ribbon 140, 142. First resistive ribbon 140 and second resistive ribbon 142 can extend substantially parallel to each other across base layer 138.

[0061] Flexible circuit board 122 also includes a plurality of conductive paths formed on electrically insulating base layer 138. For example, flexible circuit board 122 includes a neutral path 148 that electrically couples the first end of each of resistor strips 140 and 142 to each other and to a neutral terminal 150. Flexible circuit board 122 also includes a first switching power line 152 that electrically couples the second end of each of first resistor strips 140 to each other and to a first switching power terminal 154 located near the top of base layer 138. Flexible circuit board 122 also includes a second switching power line 156 that electrically couples the second end of each of second resistor strips 142 to each other and to a second switching power terminal 158 located near the top of base layer 138.

[0062] Flexible circuit board 122 also includes an active conductive path 160 extending from a first active terminal 162 adjacent to but electrically isolated from first switch power terminal 154, and a second active terminal 164 adjacent to but electrically isolated from second switch power terminal 158. Active path 160 and active terminals 162, 164 can be powered or driven by a 120V or 220V AC power source, for which neutral path 148 and terminal 150 can serve as a return path 148 and return terminal 150. Flexible circuit board 122 also includes a first gate 166 adjacent to but electrically isolated from first active terminal 162, and a second gate 168 adjacent to but electrically isolated from second active terminal 164. The terminals described herein can be soldered to allow other electronic components to be electrically connected to flexible circuit board 122 by soldering.

[0063] The first switch power terminal 154 is located above the first active terminal 162, and the first active terminal 162 is located above the first gate 166 on the base layer 138. The second switch power terminal 158 is located below the second active terminal 164, and the second active terminal 164 is located below the second gate 168 on the base layer 138. The reversal of the order of the respective first and second components facilitates the connection of control electronics, as further described below, such as controlling active power switches such as TRIACs, thyristors, power MOSFETs, IGBTs, etc. The flexible circuit board 122 also includes a top protective layer that covers the remaining electrical components of the flexible circuit board 122 to protect them from water intrusion or other potential contaminants.

[0064] Figure 12 and 13 1 and 2 are rear and left views of the heater 100 with the flexible circuit board 122 coupled thereto, respectively. Figure 12 and 13 As shown, the flexible circuit board 122 can be wrapped around the body 102 of the heater 100 such that a first end of the flexible circuit board 122 is adjacent to a second end of the flexible circuit board 122 and a first end of the resistive ribbons 140, 142 is adjacent to a second end of the resistive ribbons 140, 142. In other words, the flexible circuit board 122 can wrap around all or substantially all of the body 102. The flexible circuit board 122 can have a non-zero radius of curvature, such as a radius of curvature between one-quarter inch and four inches, between half an inch and two inches, or between one inch and one and a half inches.

[0065] The first and second resistive strips 140 and 142, and thus the first and second heating elements 144 and 146, can be located on the bottom 108 of the body 102, and each of the terminals 154, 158, 162, 164, 166, and 168 can be located on the top 110 of the body 102, for example, on a curved rear surface of the top 110 of the body 102. The first switch power terminal 154, the first active terminal 162, and the first gate 166 are located near the left side wall 112, and the second switch power terminal 158, the second active terminal 164, and the second gate 168 are located near the right side wall 114. The neutral terminal 150 can be located on the top 110 of the body 102, for example, on a curved front surface of the top 110 of the body 102 opposite its rear surface.

[0066] Figure 14 Shown Figure 5 Another perspective view of a heater with additional components coupled thereto. For example, Figure 14A first TRIAC 170 is shown coupled or mounted on a second stud 116, extending radially away from and perpendicular to the right side wall 114. While a TRIAC 170 is used in the illustrated embodiment, any suitable switch, such as those described above, may be used in alternative embodiments. The circular cross-sectional shape of the top 110 of the body 102, truncated by the right side wall 114, provides a relatively flat surface on which the TRIAC 170 may be mounted. Electrical leads 172 of the TRIAC 170 may be coupled to the second switch power terminal 158, the second active terminal 164, and the second gate 168, so that the TRIAC 170 may control the operation of the second resistive strip 142 and, therefore, the second heating element 146. A nut 174 may be threaded onto the stud 116 above the TRIAC 170 to secure the TRIAC 170 to the right side wall 114 and the body 102 of the heater 100.

[0067] Despite Figure 14 112 , and a second nut can be coupled to the first stud 116 to secure the second TRIAC in place. Electrical leads of the second TRIAC can be coupled to the first switch power terminal 154, the first active terminal 162, and the first gate 166 so that the second TRIAC can control the operation of the first resistive strip 140 and, therefore, the first heating element 144. In alternative embodiments, the TRIAC 170 can be coupled to the body 102 in any suitable manner and at any suitable location, such as by any suitable mechanical fastener (e.g., screws, bolts, nails, etc.), any suitable adhesive (e.g., thermally conductive and / or non-conductive adhesive, glue, epoxy, etc.), or by welding, such as to the top of the bulkhead 106, to the bottom of the engine 176, or between the bulkhead 106 and the engine 176.

[0068] Heater 100 includes two TRIACs, each independently controlling a corresponding heating element comprised of three resistance strips. In alternative embodiments, the heater may include one TRIAC controlling a single heating element, or controlling three, four, five, six, eight, or more TRIACs, each independently controlling a corresponding heating element. Similarly, in alternative embodiments, the heating elements may include a single, two, four, five, six, eight, or more resistance strips. In such alternative embodiments, body 102, such as top 110 of body 102, may include a plurality of flat walls similar to flat walls 112 and 114, with the number of the plurality of flat walls matching the number of TRIACs.

[0069] Figure 14 As also shown, the motor 176 can be mounted to the top of the heater 100, for example, using first and second fasteners (e.g., screws 192) extending through holes 120 to mount the motor to the top surface of the bulkhead 106, as described above, and can be assisted by motor mounts 188, which can further stabilize the motor 176 relative to the rest of the heater 100. In alternative embodiments, the motor 176 can be mounted to the top of the heater 100 in any suitable manner, such as using any suitable mechanical fasteners (e.g., screws, bolts, nails, etc.), or any suitable adhesive (e.g., glue, epoxy, etc.), or a friction or interference fit. The motor 176 can include a static 12V, 24V, or any other suitable voltage DC brushless motor, a DC brushless motor, a switched reluctance motor, a universal motor, or an AC induction motor, and can be sealed to the fluid flowing through the heater 100 using various sealing elements (e.g., compression face gaskets), for example, to prevent the fluid from escaping through holes 118, 120.

[0070] Figure 14 Further shown is a spacer 178 having a channel 180 extending therethrough and positionable over the slot 126. The channel 180 can have a slot shape that matches the slot 126 such that the slot 126 and the channel 180 can form a single passageway that can transport water or other fluid from within the interior 128 of the heater 100 and out of the heater 100 and its electrical components.

[0071] Figure 15 An impeller 182 is shown that can be mounted within the interior 128 of the heater 100. The impeller 182 can be a jet-driven impeller. For example, the impeller 182 can have two, three, or any other suitable number of blades 184 and a central opening 186 sized to receive a shaft 190 extending from the motor 176 through the hole 118 in the bulkhead 106, through the interior 128 of the heater 100, and connected to the impeller 182.

[0072] In an alternative embodiment, shaft 190 is not directly physically coupled to motor 176, and shaft 190 does not extend through aperture 118 in bulkhead 106. In this alternative embodiment, the first magnetic element is directly physically coupled to motor 176, the second magnetic element is directly physically coupled to shaft 190, and the first and second magnetic elements are magnetically coupled to each other. Thus, motor 190 can be actuated to directly drive rotation of the first magnetic element, which can cause rotation of the second magnetic element via magnetic coupling, and the rotation of the second magnetic element can cause rotation of shaft 190 and impeller 182. In this alternative embodiment, shaft 190 and impeller 182 are magnetically coupled to motor 176. In another alternative embodiment, shaft 190 can be physically or magnetically coupled to motor 176 through a gearbox or other intervening component.

[0073] The shaft 190 can transmit torque from the motor 176 to the impeller 182 to drive rotation of the impeller 182 and thereby drive a fluid, such as water, through the interior 128 of the heater 100. As further described below, the impeller 182 can be mounted at or near the bottom of the body 102 of the heater 100, or closer to the bottom end of the body 102 than the slot 126, so that the heater 100 can be used in fluids having low liquid levels.

[0074] Heater 100 can be incorporated into a thermal immersion circulator for various applications. During use, motor 176 can be turned on to drive impeller 182, and the speed of impeller 182 can be controlled to control the flow rate of a fluid, such as water, through heater 100. In some embodiments, and particularly when heater 100 is used to heat a fluid, motor 176 can be used to rotate impeller 182 in a first direction to cause the fluid to flow upward, i.e., through an opening located in the center of annular flange 104 at the bottom of heater 100, through interior 128 of body 102 of heater 100, out of body 102 through slot 126 in the tubular sidewall of body 102, through channel 180 of channel spacer 178, and out of housing 16 through opening 18 in the sidewall of housing 16. In this embodiment, the openings located in the center of annular flange 104 and at the bottom end of body 102 are the inlet of heater 100, slot 126 is the outlet of heater 100, and opening 18 is the outlet of housing 16, and the inlet can be larger than the outlet.

[0075] By installing the heater 100 in a thermal immersion circulator and placing the thermal immersion circulator in the fluid so that the bottom of the heater 100 is exposed to the fluid, the fluid (e.g., water) can be introduced into the heater 100 by the impeller 182 from the bottommost end of the heater 100. Furthermore, the motor 176 can drive the impeller 182 to rotate fast enough to pump water through the interior 128 of the body 102, even when the water within the body 102 is exposed to the atmosphere, such as when the heater 100 is used to heat water having a very low water level (e.g., below the bottom of the tank 126). For example, a thermal immersion circulator including the heater 100 can be used to heat fluid having a depth of less than 1.5 inches.

[0076] Fluid at a higher temperature rises above the same fluid at a lower temperature, so introducing the fluid into the heater 100 from the bottom allows relatively cooler fluid to be drawn into the heater, thereby allowing the fluid to be heated more effectively and efficiently. Further, by drawing water at the bottom of the heater 100 and transporting it upward through the body 102, it helps to clear any air bubbles within the heater 100 and can help reduce the level of noise generated by a thermal immersion circulator including the heater 100, for example, by reducing cavitation within the heater 100. Additionally, locating the outlet for fluid flow on the side of the body 102, rather than at the top of the body 102 and the side of the housing 16, can make the thermal immersion circulator including the heater 100 more compact because the motor 176 and other electrical components of the thermal immersion circulator (e.g., a power source such as a battery or an electrical cord for plugging into a wall outlet) can be at the top of the heater 100 within the housing 16.

[0077] In other embodiments, the motor 176 can be used to drive the impeller 182 to rotate in a second direction opposite to the first direction to cause the fluid to flow downward, i.e., through the slots 126, through the interior 128 of the body 102 of the heater 100, and out through the opening at the center of the annular flange 104 at the bottom of the heater 100. In such an embodiment, the opening at the center of the annular flange 104 and at the bottom end of the body 102 is the outlet of the heater 100, the slots 126 are the inlet of the heater 100, the opening 18 is the inlet of the housing 16, and the outlet can be larger than the inlet.

[0078] When the heater 100 is in use, a large amount of current can flow through the control electronics (e.g., TRIAC) and other electronic components of the flexible circuit board 122. For example, using a 120V AC, 60Hz power source, each heating element 144, 146 can draw 550±50W of power. The heater 100 can draw a total power of 1100±100W. In some cases, this large power draw can heat the control electronics (e.g., TRIAC) to undesirably high temperatures.

[0079] In heater 100, control electronics (e.g., a TRIAC or any suitable electronic switch, either encapsulated within an encapsulant or encapsulating package, or unencapsulated and integrally constructed with body 102) are mounted in direct contact with a flat surface of body 102, which may comprise a highly thermally conductive material such as steel, and in direct contact with flexible circuit board 122. That is, the control electronics (e.g., a TRIAC) and flexible circuit board 122 may be in direct contact with the same thermally conductive surface. In this context, the term "direct contact" includes contact through one or more substrate layers, such as adhesive layers, pads, thermally conductive films, or grease. Fluid (e.g., water) pumped through heater 100 can serve as a coolant for the control electronics (e.g., a TRIAC), drawing heat conducted from the control electronics away from the control electronics through body 102. Thus, the control electronics (e.g., a TRIAC) can be water-cooled. Substantially all of the heat generated by the TRIAC can be transferred to the fluid being heated, allowing the TRIAC to reach a temperature substantially equal to that of the fluid being heated. This heat exchange path simultaneously transfers heat from the components benefiting from cooling to the fluid being heated. Thus, the heating elements 144 and 146 and the control electronics may be thermally or thermally conductively coupled to the fluid passing through the body 102 .

[0080] In some embodiments, the interior surfaces 130 and 134 of the heater 100 can be textured or textured so that when the thermal immersion circulator 10 and heater 100 are removed from the heated fluid, the surfaces 130 and 134 retain some of the heated fluid (e.g., some of the fluid may adhere to the textured surfaces 130 and 134 via surface tension). For example, the surfaces 130 and 134 can be textured so that they are hydrophilic. The surfaces 130 and 134 can also be coated with a hydrophilic coating to improve the retention of fluids, such as water, by the surfaces 130 and 134 when the heater 100 is removed from the body of fluid. The water or any other fluid retained on the surfaces 130 and 134 can provide a heat reservoir to protect the thermal immersion circulator 10 and heater 100 from transient thermal effects resulting from its removal from the body of heated fluid, such as by removing heat from the heater 100 via the latent heat of vaporization of the fluid.

[0081] In some embodiments, the heater 100 includes one or more temperature-responsive sensors, such as thermistors, thermocouples, resistance temperature detectors (RTDs), etc. As a specific example, the heater 100 can include three thermistors: a first thermistor near the bottom of the body 102, such as on the flange 104 or the housing 116, a second thermistor near the slot 126, such as on the body 102 or the housing 116 adjacent to the slot 126, and a third thermistor on the flexible circuit 122, such as on the first or second heating element 144 or 146.

[0082] The first and second thermistors, located at the opening of the interior 128 of the heater 100, can provide information about the temperature of the heated fluid to facilitate more precise control of the heater 100. The first and second thermistors can measure the temperature of the heated fluid when the heating elements 144, 146 are off to reduce interference in the fluid temperature measurement caused by the operation of the heating elements 144, 146. The third thermistor can provide information about the temperature of the heating elements 144, 146 to prevent them from overheating.

[0083] A thermal immersion circulator including heater 100 may include control circuitry or a computer that can direct the operation of flexible circuit board 122, such as via a TRIAC. As an example, the control circuitry or computer can receive a desired or target temperature for the fluid to be heated, such as a temperature specified by a user of the thermal immersion circulator. The control circuitry or computer can direct the TRIAC to turn on first and second heating elements 144, 146 and can direct motor 176 to rotate impeller 182. Heating elements 144, 146 can conduct heat to the fluid within interior 128 of body 102 through body 102. Once the temperature of the heated fluid reaches the target temperature, as measured by the first or second thermistor, the control circuitry or computer can direct the TRIAC to turn off heating elements 144, 146.

[0084] To maintain the fluid at the target temperature, the control circuit or computer can instruct the TRIAC to intermittently turn on one of the heating elements 144, 146. In some embodiments, the control circuit or computer can instruct the TRIAC 170 to turn the second heating element 146 on and off at predetermined time intervals. In other embodiments, the control circuit or computer can instruct the TRIAC 170 to turn on the second heating element 146 when the temperature of the heated fluid measured by the first or second thermistor drops below the target temperature by a predetermined amount, and to turn off the second heating element 146 when the temperature of the heated fluid measured by the first or second thermistor rises above the target temperature by a predetermined amount.

[0085] As another example, if the temperature of one of the heating elements 144 , 146 measured by the third thermistor exceeds a threshold temperature, such as a temperature at which the flexible circuit board 122 may suffer damage, the control circuit or computer may instruct the TRIAC to turn off the heating element 144 , 146 .

[0086] In some embodiments, the thermal immersion circulator 10 may include an accelerometer that may be coupled to a control circuit or computer. When the signal from the accelerometer exceeds a predetermined threshold, the control circuit or computer may instruct the TRIAC to turn off the heating elements 144 and 146, and the control circuit or computer may turn off the motor 176 and the impeller 182. In such an embodiment, the thermal immersion circulator 10 automatically turns off when the thermal immersion circulator 10 is knocked over in a pot or picked up by an operator.

[0087] Figure 16 Components of another embodiment of a thermal immersion circulator 200 are shown in an exploded view. The thermal immersion circulator 200 may have components similar or identical to corresponding components of the thermal immersion circulator 10, with some differences discussed herein. The thermal immersion circulator 200 includes a heater 202 similar to the heater 100, a motor 204 similar to the motor 176, a connecting nut 206 similar to the connecting nut 40, and a printed circuit board including electronics 208. The thermal immersion circulator 200 may also include a housing 210 similar to the housing 16, a housing bumper 212, an impeller 214 similar to the impeller 182, and an inlet 216 similar to the inlet 14. The thermal immersion circulator 200 may also include a top cover assembly 218 similar to the top cover assembly 28, a support basket 220 for supporting the printed circuit board and electronics 208 within the housing 210, a power cord 222 similar to the power cord 32, and a clip 224 similar to the clip 30.

[0088] The method of assembling the thermal immersion circulator 200 may include, but not necessarily in the following order: inserting the heater 202, the motor 204, and the printed circuit board and electronics 208 into the housing 210 and securing the heater 202, the motor 204, and the printed circuit board and electronics 208 to the housing 210 using the coupling nut 206, as described below with reference to Figure 21As described in more detail. The method may further include inserting the support basket 220 into the housing 210 so that the support basket 220 is tightly engaged by the housing 210 and tightly engages the printed circuit board and electronic device 208. The method may further include coupling the power cord 222 to the housing 210, and coupling the power cord 222 to the printed circuit board and electronic device 208 through the housing 210. The method may further include coupling or engaging the components inserted into the housing 210 to the housing 210 in a waterproof manner, such as by ultrasonic welding, applying a sealant or adhesive, or using a mechanical seal. The method may also include coupling the top cover assembly 218 to the top of the support basket 220 and the housing 210. The method may also include coupling the propeller 214 to the drive shaft 232 (see Figure 17 ), the drive shaft 232 is coupled to the engine 204, and the housing buffer 212 is inserted into the groove in the housing 210, which will be referred to below Figure 21 The method may further include coupling the inlet 216 to the bottom end of the housing 210 . The method may also include coupling the clamp 224 to the power cable 222 .

[0089] Figure 17 and 18 Additional details of the motor 204 and the printed circuit board and electronics 208 are shown. For example, the motor 204 can have a housing that includes a top plate 226, a cylindrical housing 228, and a bottom plate 230. The mechanical or electrical components of the motor 204 can be housed within the housing 228 between the top plate 226 and the bottom plate 230 and can be used to rotate a drive shaft 232 having a diameter of about 4 mm, for example, at a speed of at least 1800 rpm, for example, 2600 rpm is suitable. Figure 18 As shown, the top plate 226 may include a vertically extending ridge or fin 234 that spans the top surface of the top plate 226 and extends vertically. The ridge 234 may include two openings 236 that may receive screws or other fasteners 242 to couple the printed circuit board and electronic device 208 to the ridge 234. The top plate 226 may also include a raised cylindrical base 238, a capacitor or other energy storage device 240 (see FIG. Figure 16 ) can be mounted on the cylindrical base 238.

[0090] The bottom plate 230 may include a boss 233 extending vertically away from a peripheral flange 234, and a seal 236 positioned to extend around the boss 233 where the boss 233 meets the flange 234. The boss 233 may have a cross-sectional shape that matches the cross-sectional shape of the interior 128 of the top 110 of the body 102, so that the boss 233 can mate with the top 110 of the body 102 while the flange 234 engages the top of the body 102 and the seal 236 seals the interior 128 of the body 102 from its exterior. In such an implementation, the bottom plate 230 may form the diaphragm 106 of the heater 100.

[0091] The printed circuit board and electronics 208 can be coupled to the spine 234 of the top plate 226, such as with screws 242, the capacitor 240 can be coupled to the base 238, and the heat sink 244 (see Figure 17 ) can be coupled to the base 238 and capacitor 240 so that heat generated by the capacitor 240 can be transferred to the heat sink 244 and from there to the top plate 226. In an alternative embodiment, the circulator 200 does not include the heat sink 244, and the heat generated by the capacitor 240 can be transferred directly to the top plate 226. The motor housing can provide a heat path to transfer heat from above the engine 204 to below the engine 204. For example, heat from the printed circuit board and electronics 208 can flow through the spine 234, through the top plate 226, through the housing 228, through the bottom plate 230, and into the fluid flowing through the heater coupled to the bottom plate 230. Similarly, heat from the capacitor can flow through the heat sink 244, through the base 238, through the top plate 226, through the housing 228, through the bottom plate 230, and into the fluid flowing through the heater coupled to the bottom plate 230.

[0092] These flow paths can dissipate heat from the electronic components of the circulator 200 so that the temperature of the heat sink 244 does not rise by more than 4 degrees Celsius from the temperature of the fluid flowing through the heater coupled to the bottom plate 230, or so that the temperature of the electronic components, such as those controlling the active power switches, does not exceed 105 degrees Celsius or 120 degrees Celsius, as described above. To provide effective flow paths, the top plate 226 and the bottom plate 230 can be made of a thermally conductive material, such as zinc, copper, or aluminum, and the housing 228 can be made of a thermally conductive material, such as zinc, copper, or aluminum. As two specific examples, the housing 228 can include a 1.65 mm thick copper shell or a 3.00 mm thick aluminum shell.

[0093] Figure 19A flexible circuit board 246 is shown that can be coupled to the outer surface of the heater 202. The flexible circuit board 246 can have similar components and features as the flexible circuit board 122. The flexible circuit board 246 includes a plurality (six in the illustrated embodiment) of resistive strips 248 that together form a heating element 250. The flexible circuit board 246 includes a neutral path 252 that is electrically separated from the first end of each resistive strip 248 by a gap 254. The gap 254 can be bridged by a thermal fuse that breaks or trips at a predetermined temperature, such as a thermal fuse. Overheat protection device.

[0094] As an example, the thermal fuse can be electrically coupled to the neutral path 252 and a terminal located at the edge of the heating element 250, the terminal being opposite to the neutral path 252 and spaced apart by a width of the heating element 250 (i.e., at a position equal to or greater than the neutral path 252). Figure 19 ). In another example, the thermal fuse may include a spring that biases the lead from the neutral path 252 and the first end of the resistive ribbon 248 apart from each other. The thermal fuse may include a conductive element that physically and electrically couples the leads to each other against the action of the spring and melts at a predetermined temperature. Once the conductive element melts, the spring can pass through the gap 254 and open a circuit between the neutral path 252 and the heating element 250.

[0095] Flexible circuit board 246 also includes a switched power line 256 that electrically couples the second end of each resistor strip 248 to each other and to a switched power terminal 258. Flexible circuit board 246 also includes an active terminal 260 adjacent to, but electrically isolated from, switched power terminal 258, for which neutral path 252 can serve as a return path. Flexible circuit board 246 also includes a gate 262 adjacent to, but electrically isolated from, active terminal 260. Based on their respective configurations, flexible circuit board 246 can be referred to as a "single-zone" flexible circuit board, and heater 202 including flexible circuit board 246 can be referred to as a "single-zone" heater, while flexible circuit board 122 can be referred to as a "dual-zone" flexible circuit board, and heater 100 can be referred to as a "dual-zone" heater.

[0096] A voltage of 120 volts can be supplied to the flexible circuit board 246 across the resistance band 248, which can generate 1,100 watts of power. The power to the resistance band 248 can be cycled on and off over time to provide a desired time-averaged power, such as less than 1,100 watts. The flexible circuit board 246 can also include a thermistor 264, which can be used in the same manner as any other thermistor described herein. However, as another example, the thermistor 264 can be used to determine that the circulator 200 has been removed from the fluid. For example, when the circulator 200 is immersed in the fluid, the rate of temperature change measured by the thermistor 264 is less than the rate of temperature change when the circulator 200 is removed from the fluid. Based on this difference, a threshold value for the rate of temperature change measured by the thermistor 264 can be predetermined, such that when the rate of temperature change measured by the thermistor 264 exceeds the threshold value, the heater 202 is turned off to prevent overheating. Thermistor 264 may be a surface mounted 0805 form factor thermistor coupled to traces formed in flexible circuit board 246 , which may be electrically coupled to the printed circuit board and electronic device 208 .

[0097] Figure 20 A support member 266 is shown, comprising a washer or boss 268 extending outward from the top of the support member and a groove 270 extending downward along a first side of the support member, through the bottom of the support member, and upward along the bottom of the support member. The support member 266 can be used to mount a power cord (e.g., wire 32 or wire 222) and a removable spring clip 272 to a housing 274 of a thermal immersion circulator. For example, a strain relief element at the end of the power cord can be coupled to the boss 268, such as a strain relief element whose diameter increases along the end of the cord. As another example, the clip 272 can include a wire (which can be stainless steel or any other suitable material) having a shape that matches the groove 270, thereby retaining the clip 272 on the support member 266 through friction (e.g., an interference fit). Thus, the clip 272 can be easily removed from the support member 266 and replaced with another clip if necessary. The clip 272 may also include a shaped pad 276 to bear against the side of the pot so that the side of the pot may be clamped between the housing 274 and the pad 276 by the biasing action of the clip 272 .

[0098] In some embodiments, a kit can include a thermal immersion circulator and a plurality of clips having different sizes, each clip being configured for use with a different sized pot, such as having sides of different diameters. Before using the thermal immersion circulator, a user can assess the size of the pot they are using, select a clip based on those dimensions, couple the selected clip to the thermal immersion circulator, and then begin using the thermal immersion circulator. By combining the boss 268 and the groove 270 into a single component, the support 266 can reduce costs by combining connections for multiple items (the power cord and the clip) into a single component. Because the boss 268 is located at the top of the support 266, i.e., above the groove 270, the power cord is coupled to the thermal immersion circulator above the clip. Thus, by clipping the thermal immersion circulator to the side of the pot, the user can ensure that the power cord remains outside of the heated fluid.

[0099] Figure 21 is a cross-sectional view of several components of the thermal immersion circulator 200. Figure 21 As shown, the connecting nut 206 can have external threads 284 that engage with complementary internal threads 286 of the housing 210 to secure the connecting nut 206 to the housing 210 and secure the heater 202 and other components within the housing 210. The connecting nut 206 can also include an internal seal 288 that can seal the interior of the heater 202 to the connecting nut 206 to prevent fluid from entering the interior of the heater 202 and being coupled to the rest of the thermal immersion circulator 200. The connecting nut 206 can also include an external seal 290 that can seal the interior of the housing 210 to the connecting nut 206 to prevent fluid from entering the exterior of the circulator 200 and into the rest of the thermal immersion circulator 200. The connecting nut 206 can also include internal threads 292 into which complementary external threads of the inlet 216 can be threaded to secure the inlet 216 to the other components of the thermal immersion circulator 200. The connection nut 206 and its seals 288 and 290 may allow a user to remove the inlet 216 to access the interior of the heater 202 , such as to clean the heater 202 , without disrupting the seal of the thermal immersion circulator 200 .

[0100] Figure 21 It is also shown that the housing bumper 212 can be installed so that the peripheral flange of the housing bumper 212 engages the inner surface of the housing 210 to retain the housing bumper 212 within the housing 210. The housing bumper 212 can extend out of the housing 210 through an opening in the housing 210 so that the body of the housing bumper 212 protrudes beyond the outer surface of the housing 210. The housing bumper 212 can be positioned below the seal 290 of the connecting nut 206 so that the opening in the housing 210 through which the housing bumper 212 extends does not disrupt the seal of the thermal immersion circulator. Figure 16 As shown, the housing buffer 212 can be positioned on the same side of the circulator 200 as the clamp 224, or the housing buffer 212 can be positioned on the other side of the circulator 200, which is opposite the opening 294 in the side of the housing 210 and the corresponding opening 296 in the side of the heater 202.

[0101] Housing bumper 212 can be made of a material that has a higher coefficient of friction than housing 210 and is more flexible than housing 210. Therefore, when a user clamps thermal immersion circulator 200 to the side of a pot, the body of housing bumper 212, which extends through the opening in housing 210, can rest against the side of the pot, separating housing 210 from the pot and preventing it from contacting the pot's side. Consequently, vibrations from motor 204 and impeller 214 are not directly transmitted (or at least more indirectly) to the pot. Furthermore, the higher coefficient of friction of housing bumper 212 relative to the pot's side reduces movement of circulator 200 that could otherwise be caused by vibrations from motor 204 and impeller 214. Furthermore, when a user clamps thermal immersion circulator 200 to the side of a pot, openings 294 on the side of housing 210 and openings 296 on the side of heater 202 can face away from the pot's side, improving fluid dynamics as the fluid exits thermal immersion circulator 200.

[0102] Figure 21 It is also shown that the inlet 216 may include an upper flow guide 278 that may define an upper and outer flow boundary surface 282 for fluid entering the circulator 200 through the inlet 216, and a lower flow guide 280 that may define a lower and inner flow boundary surface 320 for fluid entering the circulator 200 through the inlet 216. The upper flow guide 278 may include an outer edge portion 298 that is connected by a plurality of (e.g., three) spokes or struts 302 (also shown in FIG. Figure 16 298 are coupled to the inner hub portion 300. Each strut 302 can extend radially inward and outward between the inner hub portion 300 and the outer rim portion 298 and can have an airfoil-shaped body. In some embodiments, each strut 302 is also tilted at an angle or has a generally spiral shape around the inner hub portion 300, such that the struts 302 form a fixed propeller or inductor having a pitch or angle of attack that is the same as the pitch or angle of attack of the impeller 214, in the same or opposite direction.

[0103] The lower flow guide 280 can include a housing 304 that can be coupled to the hub 300 of the upper flow guide 278, for example, by fasteners such as screws 306, by adhesive, or in any other suitable manner. In some embodiments, the upper flow guide 278 can be integrally formed with the lower flow guide 280. The lower flow guide 280 can also include a frame 310 that can be clamped into or otherwise coupled to the housing 304, a magnet 308 held between the housing 304 and the frame 310, and an anti-skid pad 312 that can be clamped into or otherwise coupled to the frame 310.

[0104] When the thermal immersion circulator 200 is in use, the motor 204 can be operated to rotate the impeller 214 to draw heated fluid into the circulator 200 and heater 202 inwardly through the inlet 314 of the inlet 216, inwardly and upwardly through the flow path 316 in the inlet 216, and upwardly through the outlet 318 of the inlet 216. The inlet 314 can extend 360° around the inlet 216 to improve fluid intake into the inlet 216. The flow path 316 is bounded at its upper and outer sides by the upper and outer flow-bounding surface 282 of the upper flow guide 278 and at its lower and inner sides by the lower and inner flow-bounding surface 320 of the lower flow guide 280. The outlet 318 can be divided into three smaller outlets by the struts 302, and the combination of these three smaller outlets can be collectively referred to as outlet 318.

[0105] The upper and outer flow-bounding surface 282 and the lower and inner flow-bounding surface 320 can have a profile comprising a b-spline and can be curvature-continuous to improve the fluid dynamics of the heated fluid as it flows through the inlet 216. The cross-sectional area of ​​the flow path 316 decreases as the flow path 316 extends inward and upward. For example, the contraction ratio of the flow path 316, which may correspond to the ratio of the cross-sectional area of ​​the inlet 314 extending 360° around the inlet 216 to the cross-sectional area of ​​the outlet 318, can be greater than 1.0, can be between 1.6 and 2.4, and can be 2.0 as a specific example. Furthermore, the contraction ratio of the flow path through the heater 202, which corresponds to the ratio of the area of ​​the opening at the bottom of the heater 202 to the area of ​​the opening 296 on one side of the heater 202, can be between 4 and 7, or approximately 5.25. Such features can reduce cavitation and noise generated by the circulator 200 by reducing the magnitude of the pressure gradient generated in the fluid as it flows through the inlet 216.

[0106] The inlet 216 allows the circulator 200 to stand upright in the pot while resting on the non-skid pad 312, which may be formed of silicone to reduce the chance of the circulator 200 tipping over in the pot and allow the circulator 200, such as Figure 22 10 is shown in FIG. 1 , held in the pot by magnets 308. In such an embodiment, Figure 22 As shown in the circulator 10 of FIG. 1 , the clip 272 can be omitted. In such an embodiment, the magnet 308 can be attracted by the ferromagnetic material in the pot. In alternative embodiments, the pot or an additional component, such as a base coupled to the pot, can include a magnet, and the circulator 200 can include a ferromagnetic material, for example, in place of the magnet 308. In some specific embodiments, the magnet 308 can be a neodymium magnet and can be cylindrical having a height and a diameter, wherein the ratio of the height to the diameter is at least 0.4.

[0107] The inlet 216 also provides an inlet 314 to the circulator at a relatively low height so that even when the level of the heated fluid is low, the fluid can be drawn into the circulator 200. The inlet 314 can also have a height or distance between the upper guide 278 and the lower guide 280 that matches or is slightly smaller than the diameter of the power cord 222 or the outer jacket of the power cord 222. Thus, when the circulator 200 is not in use by a user, the power cord 222 can be wrapped around the housing 210 and fit snugly within the opening 314, such that the power cord 222 is retained within the inlet 314 by friction, such as by an interference fit between the inlet 216 and the power cord 222.

[0108] Any of the thermal immersion circulators described herein can be controlled in any suitable manner. For example, the thermal immersion circulator can be communicatively coupled to a source of instructions or commands, such as a control subsystem, a terrestrial or satellite transmission device, or an RF or NFC beacon. The communicative coupling can be constrained (i.e., wire, fiber optic, cable). The communicative coupling can be unconstrained (i.e., radio frequency or microwave frequency transmitters, receivers, and / or radio; infrared transmitters and / or receivers).

[0109] The thermal immersion circulator can include one or more receivers or ports for receiving communications. For example, the thermal immersion circulator can include a USB-compatible port for receiving communications. The port can be accessible from outside the housing of the thermal immersion circulator. The port can advantageously facilitate communication coupling between the thermal immersion circulator and an external source of signals or information, such as via one or more wires, ribbon cables, optical fibers, or electrical cables. This can be used to provide control signals from the external source to the thermal immersion circulator to control the operation of the thermal immersion circulator.

[0110] The thermal immersion circulator may include a port or receiver or connector or socket for receiving control signals or other inputs. For example, the thermal immersion circulator may include a wired port or wired receiver for receiving signals from an external source (e.g., Electrical or optical signaling). For another example, the thermal immersion circulator may include a wireless port or wireless receiver (e.g., a receiver, transceiver, radio, 802.11 compatible, radio frequency, microwave frequency or infrared signaling). For example, compatible The radio can provide short-range wireless communication therebetween. The thermal immersion circulator can include one or more antennas (eg, stripline RF antennas) for wireless communication.

[0111] In some embodiments, the thermal immersion circulator may include an internal integrated input controller, such as coupled to a printed circuit board thereof. Input received by the thermal immersion circulator, via any of the input methods described herein, may include instructions or commands to turn on the circulator's heater, turn off the circulator's heater, heat the fluid to a desired temperature, heat the fluid for a desired time, heat the fluid sequentially to a plurality of different temperatures for a plurality of different times, or follow any other suitable sequence of instructions.

[0112] The thermal immersion circulator 10 and the thermal immersion circulator 200 can be used in a variety of applications. Generally, the thermal immersion circulators described herein can be used to heat or circulate any fluid that can safely flow through a thermal immersion circulator. As a specific example, the thermal immersion circulators described herein can be used for sous vide cooking, a technique that cooks food at lower temperatures than typical temperatures (e.g., 150-160°F) for longer than usual. As another example, the thermal immersion circulators described herein can be used in laboratory environments, such as environmental, microbiological, or other laboratories.

[0113] Those skilled in the art will recognize that many of the methods or algorithms described herein may employ additional actions, may omit some actions, and / or may perform actions in an order different from the order specified. The various embodiments described above may be combined to provide further embodiments. The entire contents of U.S. Provisional Patent Application Serial No. 62 / 021,530, filed on July 7, 2014, U.S. Provisional Patent Application Serial No. 62 / 095,669, filed on December 22, 2014, U.S. Provisional Patent Application Serial No. 62 / 110,228, filed on January 30, 2015, U.S. Provisional Patent Application Serial No. 62 / 195,199, filed on July 21, 2015, U.S. Provisional Patent Application Serial No. 14 / 789,414, filed on July 1, 2015, and U.S. Provisional Patent Application Serial No. 62 / 242,864, filed on October 16, 2015, are incorporated herein by reference. Aspects of the embodiments can be modified, if necessary, to employ systems, circuits, and concepts of the various patents, applications, and publications to provide yet further embodiments.

[0114] These and other changes can be made to the embodiments in light of the above detailed description. Generally, the terms used in the claims should not be construed to limit the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments and the full scope of equivalents of the claims. Therefore, the claims are not limited by this disclosure.

Claims

1. A thermal immersion circulator comprising: Heater, including: a body having a tubular sidewall including a first end and a second end spaced apart from the first end by a length of the body; an inlet proximate the first end, through which fluid can be pumped; an outlet through which the fluid can be discharged from the interior of the thermal immersion circulator; a flexible circuit board wrapped around an outer surface of the body between the inlet and the outlet, the flexible circuit board including a plurality of resistance strips forming a heating element that heats the fluid; an impeller disposed within the body; and a switch electrically coupled to control the heating element and physically and thermally coupled to the tubular sidewall of the body; an engine, the engine being mounted at least proximate the second end of the body; a shaft magnetically coupling the engine to the impeller, wherein the switch and the flexible circuit board are in contact with the same heat-conducting surface of the main body, and wherein the switch and the heating element are thermally conductively coupled to a fluid passing through the body.

2. The thermal immersion circulator of claim 1 , further comprising: a first magnetic element, the first magnetic element being directly physically coupled to the engine; and a second magnetic element directly physically coupled to the shaft; wherein the first magnetic element and the second magnetic element are magnetically coupled to each other; wherein actuation of the engine directly drives rotation of the first magnetic element, the rotation of the first magnetic element causes rotation of the second magnetic element via magnetic coupling, wherein the rotation of the second magnetic element causes the shaft and the impeller to rotate.

3. The thermal immersion circulator according to claim 1, wherein: The tubular sidewall has an upper portion and a lower portion, the upper portion having a planar surface on which the switch is physically and thermally mounted.

4. The thermal immersion circulator according to claim 1, wherein: The switch is an active power switch, wherein heat generated by the active power switch is transferred to fluid within the fluid flow channel in the tubular sidewall.

5. The thermal immersion circulator of claim 4, wherein the switch is a packaged TRIAC.

6. The thermal immersion circulator of claim 1, wherein: The inlet is proximate at least a first end of the body, and at least a portion of the outlet is spaced relative to at least a portion of the inlet and relative to a second end of the body.

7. The thermal immersion circulator according to claim 6, wherein: The entirety of the outlet is spaced closer to the second end than the entirety of the inlet.

8. The thermal immersion circulator of claim 6, wherein: The tubular sidewall forms the inlet at the first end.

9. The thermal immersion circulator of claim 1, wherein: The flexible circuit board is wrapped at an angle about at least three quarters of the outer surface of the tubular side wall.

10. The thermal immersion circulator of claim 1, wherein: The impeller is positioned closer to the inlet than the outlet.

11. The thermal immersion circulator of claim 1 , wherein: The inlet has a longitudinal central axis and an inlet port that curves at least partially about the longitudinal central axis, wherein the thermal immersion circulator further comprises a support member including a boss for receiving a strain relief element of a power cord and a recess for receiving a spring clip, wherein the support member, the boss, and the recess are formed from a single, unitary piece of material.

12. The thermal immersion circulator of claim 11, wherein: The power cord has a diameter greater than a height of the inlet to fit snugly within the inlet and engage with the inlet with an interference fit.

13. The thermal immersion circulator of claim 1 further comprising a flat bottom surface including a non-skid pad formed of silicone and a magnet to maintain the position of the thermal immersion circulator within the pot having a ferromagnetic material.

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