Fire shields for variable frequency drive enclosures

Abstract

Embodiments of the present disclosure relate to a fire hood for a variable frequency drive enclosure. The fire hood enclosure utilizes an external metal hood assembly that can be attached to a wall mounted variable frequency drive (VFD) in a field before or after the VFD is installed to provide adequate fire protection as defined by UL2043: Fire Test for Heat and Visible Smoke Release (UL2043 Fire Test). The fire hood enclosure is associated with a VFD, where polymeric materials may be used as an integral part of its enclosure shell.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to variable frequency drives, and more particularly to a fire shield for a variable frequency drive enclosure. Background Art

[0002] A variable frequency drive (VFD) is a motor controller that drives a motor by varying the frequency and voltage supplied to the motor. Other names for VFDs are variable speed drives, adjustable speed drives, frequency drives, AC drives, micro drives, and inverters.

[0003] Variable frequency drives (VFDs) are often made of polymer materials for a portion of the enclosure of the VFD due to its cost, weight, and aesthetic advantages. However, polymer materials produce a lot of smoke when burned, which is undesirable and difficult to pass compliance tests, such as UL2043: Fire Test for Heat and Visible Smoke Release (UL2043 Fire Test).

[0004] Due to commercial costs in the remaining markets, it is not practical to design a housing with metal alone in order to pass the UL2043 fire test. Therefore, an alternative solution is needed to manufacture a more cost-effective and practical VFD using a polymer housing that can be accepted where UL2043 fire test compliance is required. Summary of the invention

[0005] The present invention provides a housing for a variable frequency drive, the variable frequency drive including a 3D shape, an upwardly directed airflow discharge port, a housing configured to conform to the 3D shape of the variable frequency drive, and a cooling air inlet or baffle having a tortuous path that hinders flame transmission. The housing is a fireproof hood having an airflow discharge port that matches the airflow discharge port of the variable frequency drive.

[0006] The present invention also provides a fireproof cover set for a variable frequency drive, the fireproof cover set comprising a front cover, a rear cover and an air inlet baffle. The front cover, the rear cover and the air inlet baffle are configured to cooperate with the variable frequency drive and are fire-resistant. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a perspective view of a fire-proof enclosure-enclosed variable frequency drive (VFD) according to certain embodiments of the present disclosure.

[0008] Figure 2 is an exploded view of a fire-shielded enclosed VFD according to certain embodiments of the present disclosure.

[0009] Figure 3 is a perspective view of a VFD unit according to certain embodiments of the present disclosure.

[0010] Figure 4 According to some embodiments of the present disclosure Figure 3 An enlarged stereoscopic view of portion A.

[0011] Figure 5 According to some embodiments of the present disclosure Figure 3 An enlarged stereoscopic view of portion B.

[0012] Figure 6 is a perspective view of an air intake baffle according to certain embodiments of the present disclosure. DETAILED DESCRIPTION

[0013] Now, reference is made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Whenever possible, corresponding or similar reference numerals are used in all drawings to refer to the same or corresponding parts. Moreover, when there may be more than one element of the same type, the various elements described herein are referenced jointly or individually. However, these references are merely exemplary in nature. It should be noted that, unless explicitly stated in the appended claims, any reference to an element in the singular may also be interpreted as relating to the plural, and vice versa, without limiting the scope of the present disclosure to an exact number or type of such element.

[0014] Now, refer to Figure 1 ,Should Figure 1 1 is a perspective view of a fire hood enclosed variable frequency drive (VFD) 100 according to certain embodiments of the present disclosure. The fire hood enclosed VFD 100 may include a VFD unit 105 enclosed by a front fire hood 110 and a rear fire hood 115. In certain embodiments, the front fire hood 110 wraps around the front and sides of the VFD unit 105 and encapsulates or covers them, wherein the side portion of the front fire hood 110 includes a plurality of hood vents 135 protruding from the side surface of the front fire hood 110. The plurality of vents 135 are configured to align with a plurality of air discharge ports 130 disposed on the sides of the VFD unit 105, as described below. Figure 3 and Figure 4 The VFD 100 may further include an air intake baffle 120 disposed at a bottom portion of the VFD 100. In some embodiments, the VFD unit 105 may include a polymer material to reduce production costs, and include a VFD control panel 125 configured to operate the VFD unit 105 according to user needs. In some embodiments, the fire shields 110, 115 conform to the three-dimensional shape of the VFD 105.

[0015] In some embodiments, the front fire shield 110 can be configured to wrap around the front and side portions of the VFD unit 105 when assembled, wherein the rear fire shield 115 is configured to cover the rear portion of the VFD unit 105, such as Figure 2 More clearly shown.

[0016] Now, refer to Figure 2 ,Should Figure 2 1 is an exploded view of a fire hood enclosed VFD 100 according to certain embodiments of the present disclosure. The present disclosure relates to a fire hood enclosed VFD 100, wherein certain embodiments include a VFD 105 constructed of a polymeric material housing enclosed by a fire hood 110, 115. The fire hood 110, 115 is configured to provide sufficient protection to pass a fire test, such as UL2043: Fire Test for Heat and Visible Smoke Release (UL2043 Fire Test). In certain embodiments, the fire hood 110, 115 is required to protect the polymeric housing material of the VFD unit 105 because such material may generate a significant amount of heat and smoke that would not normally comply with the UL2043 fire test.

[0017] In certain embodiments, it will be appreciated that the use of the fire shields 110 and 115 will allow the VFD 105 to be constructed generally of polymeric materials to comply with the UL2043 fire test without having to change the basic design of the VFD unit 105, as any such changes to the basic design may have a significant impact on product cost and weight. In the illustrated embodiment, the rear fire shield 115 is not configured with overlapping lips at any point of contact with the front fire shield 110, but in alternative embodiments, the rear fire shield 115 and the air inlet baffle 120 may be integral or have a combined configuration, such as lips, flanges, and other structures, to interconnect the two shield portions to form a unitary structure.

[0018] In some embodiments, a set of fire shields 110 and 115 made of metal may be configured to be attached to the VFD unit 105 to create a fire enclosure around the VFD unit 105. Certain embodiments are comprised of a back panel 115, a main cover or front fire shield 110, and an air intake baffle 120, which are all used in combination to enclose or cover the VFD unit 105.

[0019] In some designs where the back of the VFD 105 housing is already made of metal, there may be no need for the back plate 115. In some embodiments, the air inlet baffle 120 may be replaced by a metal grille (not shown) which has been found to be sufficient to meet the requirements of the UL2043 fire test.

[0020] In some embodiments, the fire shields 110, 115 provide adequate fire protection according to the requirements of the UL2043 fire test. In some embodiments, the fire shields 110, 115 can also be considered as enclosures made of metal, and therefore do not need to be further investigated by the UL2043 fire test requirements, which means that they do not need to be tested.

[0021] refer to Figure 3 ,Should Figure 3 1 is a perspective view of a VFD unit 105 according to certain embodiments of the present disclosure. In certain embodiments, the front fire shield 110 may include a side louver 135 that is configured to be oriented to discharge in an upward direction or inverted direction away from the air intake damper 120, as shown. This configuration may allow for reduced airflow of smoke and fire within the VFD unit 105. It should be appreciated that this orientation of the louver 135 is unconventional.

[0022] refer to Figure 4 ,Should Figure 4 According to some embodiments of the present disclosure Figure 3 1. In some embodiments, as discussed above, having an inverted louver 135 can direct airflow to draw smoke and fire away from the VFD unit 105 to reduce heat and smoke damage.

[0023] refer to Figure 5 ,Should Figure 5 According to some embodiments of the present disclosure Figure 3 In some embodiments, the air intake baffle 120 may include an internal duct intake portion 140 configured in a manner such as to direct flames through the internal duct to mitigate the effects of such flames, thereby preventing any fire within the VFD unit 105. Figure 5 As can be seen in FIG. 1 , air entering through the side opening (right side as shown) of baffle 120 is prevented from moving upward toward VFD 105 by plate 142 disposed between opening 140 and air inlet 144 , thereby being directed to the bottom surface of VFD 105 .

[0024] refer to Figure 6 ,Should Figure 61 is a perspective view of an air intake baffle 120 according to certain embodiments of the present disclosure. In some embodiments, the air intake baffle 120 may include an internal duct intake portion 140 and a bottom mounting portion 145. As discussed above, the internal duct intake portion 140 may be configured in a manner such as to allow the introduction of cooling air to the VFD 105 to enter but to prevent any flames from entering the fire by making an internal duct to the baffle 120 at 140 so that any flames or air must rotate several times before entering the VFD 105.

[0025] In certain embodiments, the combination of the fire shields 110 , 115 and the air inlet baffle 120 is used to provide adequate fire protection for the VFD unit 105 in a pressurized environment, as described by the UL2043 fire test.

[0026] Certain embodiments provide advantages over most VFDs 105 that are manufactured using polymer housings to reduce cost and weight but do not pass the UL 2043 fire test. Certain embodiments allow manufacturers to take advantage of those advantages and use the fire shields 110, 115 only in applications where they are clearly needed, depending on the application.

[0027] Some embodiments allow an end user of a polymer-limited or predominantly polymer-constructed VFD 105 to install the product in an area designated as a plenum where acceptance for installation is subject to, for example, UL2043 fire testing, etc.

[0028] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0029] Unless otherwise indicated herein or clearly contradictory to the context, the use of the terms "one", "an", "the", "at least one", and similar references in the context of describing the present invention (especially in the context of the appended claims) is to be interpreted as covering singular and plural forms. Unless otherwise indicated herein or clearly contradictory to the context, the term "at least one" is followed by a list of one or more items (e.g., "at least one of A and B") to be interpreted as meaning an item (A or B) selected from the listed items or any combination of two or more items in the listed items (A and B). Unless otherwise indicated, the terms "include", "have", "include" and "contain" are to be interpreted as open terms (i.e., meaning "including but not limited to"). Unless otherwise indicated herein, the description of the value range herein is intended only to be used as a shorthand method to refer to each individual value falling within the range, respectively, and each individual value is incorporated into the specification as if it is separately described herein. Unless otherwise indicated herein or clearly contradictory to the context, all methods described herein can be performed in any suitable order. Unless otherwise required, the use of any and all examples or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the present invention and is not intended to limit the scope of the present invention. No language in the specification should be construed as indicating that any unclaimed element is essential to the implementation of the present invention.

[0030] Preferred embodiments of the present invention are described herein, including the best modes known to the inventor for implementing the present invention. By reading the foregoing description, variations of those preferred embodiments will become apparent to those of ordinary skill in the art. The inventor expects that the technician will appropriately adopt such variations, and the inventor intends to practice the present invention in a manner different from that specifically described herein. Thus, the present invention includes all modifications and equivalents of the subject matter recorded in the appended claims as permitted by applicable law. Moreover, unless otherwise indicated herein or clearly contradictory to the context, the present invention encompasses any combination of the above-mentioned elements in all possible variations thereof.

Claims

1. A closed variable frequency drive, comprising: Variable frequency drive with 3D shape and upward directed airflow discharge; a housing configured to conform to the 3D shape of the variable frequency drive; as well as an air inlet baffle, the air inlet baffle being arranged at a bottom portion of the variable frequency drive, wherein the housing is a fireproof cover having an airflow discharge port that matches the airflow discharge port of the variable frequency drive, and The air intake baffle includes an air inlet, a plate disposed above the air inlet, and an inner duct portion disposed below the air inlet to allow the flow of cooling air but block fire.

2. The enclosed variable frequency drive of claim 1, wherein the fire shield is constructed of metal.

3. The enclosed variable frequency drive according to claim 1, wherein the fire cover comprises a front portion and a rear portion cooperating with the front portion.

4. The enclosed variable frequency drive of claim 1, wherein the variable frequency drive 3D shape comprises a housing constructed of a polymer material.

5. The enclosed variable frequency drive of claim 1, wherein the fire enclosure is configured to comply with UL2043: Fire Test for Heat and Visible Smoke Release.

6. The enclosed variable frequency drive of claim 1, wherein the air inlet baffle is constructed of metal.

7. The enclosed variable frequency drive of claim 1, wherein the air inlet damper is configured to comply with UL2043: Fire Test for Heat and Visible Smoke Release.

8. The enclosed variable frequency drive of claim 3, wherein when assembled, a front portion is connected to the rear portion of the fire dome.

9. The enclosed variable frequency drive of claim 8, further comprising an air inlet baffle connected to the rear portion of the fire shroud when assembled.

10. A fire cover assembly for a variable frequency drive, comprising: Front hood; rear hood; as well as an air inlet baffle, the air inlet baffle being arranged at a bottom portion of the variable frequency drive, wherein the front hood, the rear hood and the air intake baffle are configured to cooperate with a variable frequency drive and are fire resistant, wherein during assembly, the air inlet baffle is connected to the front cover and the rear cover of the fireproof cover group, and The air intake baffle includes an air inlet, a plate disposed above the air inlet, and an inner duct portion disposed below the air inlet to allow the flow of cooling air but block fire.

11. The fire cover assembly for a variable frequency drive according to claim 10, wherein the front cover and the rear cover are made of metal.

12. The fire shield assembly for a variable frequency drive of claim 10, wherein the air inlet baffle is constructed of metal.

13. The fire cover set for a variable frequency drive of claim 10, wherein the front cover and the rear cover are configured to be mounted to each other when assembled.

14. The fire cover assembly for a variable frequency drive according to claim 10, wherein the front cover, the rear cover and the air inlet baffle are configured to comply with UL2043: Fire Test for Heat and Visible Smoke Release. 15 . The fireproof cover set for a variable frequency drive according to claim 10 , wherein the front cover, the rear cover and the air inlet baffle are configured to be assembled into a hollow shell to enclose the variable frequency drive in the hollow shell when inserted. 16 . The fire cover set for a variable frequency drive according to claim 10 , wherein the front cover, the rear cover and the air inlet baffle are configured to be assembled into a housing for the variable frequency drive when assembled.

17. The fire hood assembly for a variable frequency drive of claim 10, wherein the air inlet baffle is a metal grille.

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