Patent Application
20080179309
The present invention relates to hand-held soldering irons, and more particularly to hand-held soldering irons powered by direct current.
Soldering irons are used for a variety of purposes, but are typically used to melt solder so as to solder or de-solder components to a circuit board. Typically, soldering irons are powered by electricity. The majority of soldering irons are powered by conventional AC power from an electrical wall outlet. Typically, the heating elements in such soldering iron are provided with AC power, either at line voltage or at a stepped-down AC voltage, and the soldering tips are therefore typically able to heat up more quickly and better able to maintain the desired high temperature. However, soldering irons that provide AC power to the soldering iron body, and particularly the heating element, tend to be rather bulky. As such, some soldering irons use heating elements that are DC powered, such as from internal batteries, which allows the heating elements to be more appropriately sized. However, soldering irons with DC powered heating elements typically use the exterior of the soldering tip as a return route for the DC power flowing through the heating element and also use voltages that exceed 5-7 volts. Such an arrangement runs the risk of inadvertently causing damage to more sensitive electronic components during the soldering process.
Thus, while numerous soldering iron designs have been proposed that use DC powered heating elements, they have not proven to be entirely satisfactory in some situations. Accordingly, there remains a need for alternative approaches to soldering irons with DC powered heating element(s).
In one illustrative embodiment, a soldering iron comprises an handle body having a gripping section for gripping by a user during operation of the soldering iron; an electrical step-down transformer disposed remote from the handle body and operative to convert relatively higher voltage alternating current to low voltage direct current for supply to the handle body; an electrical cord operatively connecting the transformer to the handle body; a soldering tip assembly supported by the handle body; the soldering tip having a mounting end disposed proximal the handle body and a tip end disposed distal from the handle body, the soldering tip assembly further comprising a heating element embedded therein and disposed closer to the tip end than the mounting end; the heating element electrically insulated from an exterior surface of the tip end. The soldering tip assembly may be formed as a cartridge removably mated to the handle body. The soldering tip assembly may comprise a rearward extending shroud that overlies a portion of the male plug; with an annular open space defined between the male plug and the shroud. The handle body may comprise a jack for receiving the plug, with a portion of the jack disposed in the open space when the plug is fully inserted in the jack. The electrical cord may connect to the handle body via a swiveling strain relief, with the strain relief comprising a generally spherically shaped section disposed internal to the handle body and mating with complementary recess in the handle body. The soldering iron may be adapted to heat the exterior surface of the tip end, from room temperature, to a temperature of at least 700° F. in a time period of approximately a minute and half or less, and advantageously reaches a solder melt temperature in not more than thirty seconds.
In another embodiment, a soldering iron comprises a handle body having a gripping section for gripping by a user during operation of the soldering iron; an electrical cord supplying power to the handle body; a soldering tip assembly supported by the handle body and having a mounting end disposed proximal the handle body and a tip end disposed distal from the handle body; the soldering tip assembly further comprising a heating element embedded therein and disposed closer to the tip end than the mounting end; the heating element electrically insulated from an exterior surface of the tip end; a power supply operative to supply a controlled low voltage DC power to the heating element by converting an incoming AC power.
Other aspects of various embodiments of the inventive apparatus and related methods are also disclosed in the following description. The various aspects may be used alone or in any combination, as is desired.
A soldering iron according to one embodiment of the present invention is shown in
The soldering iron 20 of
The cord 28 may be of any suitable type known in the art. The cord 28 may be a two conductor cord if the handle body 30 is not connected to ground, or may be a three conductor cord if the handle body 30 is to be connected to ground. Further, when cord 28 is carrying low voltage direct current, the electrical requirements placed on the cord 28 are advantageously lessened with respect to a cord required to carry alternating current at line voltage.
The handle body 30 extends from a rear or proximal end portion 32 nearer to where cord 28 joins handle body 30 to a forward or distal end portion 34 nearer to the soldering tip assembly 90. The handle body 30 may be generally L-shaped (sometimes referred to as pistol/gun shaped), or, as shown in
The handle body 30 may also include a strain relief 80 for helping to protect the connection between the cord 28 and the handle body 30. One example of a strain relief 80 is shown in
The soldering tip assembly 90 is removably mounted to the proximal end portion 32 of handle body 30; more particularly, the soldering tip assembly 90 is mated to tip jack 60. Referring to
In one illustrative embodiment, the soldering tip 100 may comprise approximately 2.1 grams of copper, and the heating element 102 may take the form of heating coil. The heating coil may comprise thirty-four gage wire of 80/20 nickel/chromium (e.g., Tophet A®), with a nominal resistance of 16.25 Ohms/ft. The wire may be insulated with fiberglass to an overall diameter of 0.012 inches. The insulated wire may be wound on a 0.033 inch arbor with no spacing between coils to form a finished wound element of approximately ⅝ inch in length, with an overall resistance of approximately six Ohms. The coil may be electrically insulated from the soldering tip by using suitable material, such as a zircon based cement sold under the tradename SAUEREISEN ELECTOTEMP CEMENT #8, available from Sauereisen Cements Co. of Pittsburgh, Pa.
The intermediate section 96 includes a frame 110, a barrel flange 114, and a cover 116. The frame 110 provides the basic structural support for the intermediate section 96. The frame 110 may be generally semi-cylindrical, with a chamber 112 formed thereby. The chamber 112 provides a location for housing the base portion 126 of plug assembly 120 (discussed below), with the connection tabs 128 properly protected and electrically isolated. The barrel flange 114 is connected to the forward portion of frame 110, and annularly surrounds the rear portion of barrel 108. The cover 116 may advantageously be generally tubular, with an inner diameter slightly larger than the frame 110 and barrel flange 114. The cover 116 fits over the barrel flange 114 and the frame 110 so as to generally surround chamber 112. The rear portion of cover 116 forms an annular shroud 118 that extends rearward from frame 110.
The proximal mounting portion 98 extends rearward from the intermediate section 96 and includes plug assembly 120 and annular shroud 118. Plug assembly 120 mates with tip jack 60 to electrically connect the soldering tip assembly 90 to tip jack 60. Referring to
As indicated above, the soldering tip assembly 90 is removably mounted to handle body 30. When connected, plug shaft 122 extends into a corresponding hole in jack 60 so that the appropriate electrical connections are made. When plug shaft 122 is fully seated, at least a portion of jack 60 extends into open space 99 such that shroud portion 118 of cover 116 mates to, and generally surrounds this portion of jack 60. See
The soldering tip 100 of soldering iron 20 is capable of heating very quickly, despite the heating element being powered by regulated low voltage DC power. By embedding the heating element 102 in the distal end 94, proximate soldering tip 100, the generated heat need travel only a very small distance to heat soldering tip 100. Indeed, tests have shown that the soldering tip 100 may reach a temperature of 700° F. or more, from room ambient, in approximately a minute and half or less, and advantageously reaches a solder melt temperature in not more than thirty seconds. Further, the soldering iron 20 is able to provide sufficient heat energy, and recover quickly, so as to be able to complete a seven-plug soldering iron thermal capacity test common in the industry in less than seven minutes. And, because the exterior 101 of soldering tip 100 is electrically isolated from the power flowing through heating element 102, there is a greatly reduced risk of electrically damaging any components being soldered. Further still, placement of the power supply 22 remote from handle body 30 allows the handle body 30 to be relatively lightweight. And, this configuration allows the substitution of different transformers for different markets (e.g., Europe vs. United States) without having to modify the handle body 30 or soldering tip assembly 90.
In order to conveniently provide a replacement soldering tip assembly 90, it may be advantageous for handle body 30 to include a storage compartment 56 for holding an extra soldering tip assembly 57. The storage compartment 56 may be formed by a suitable storage structure along the upper portion of handle body 30 that can pivot open (
Handle body 30 may also include a stand 58, if desired, for elevating the soldering tip 100 when not in use. Such as stand 58 may take the form of a simple generally U-shaped bent wire that is pivotally mounted to the underside of shell 40 in distal portion 34 of handle body 30. The stand 58 is moveable between a retracted/storage position (
In the embodiments above, it has been assumed that the soldering tip assembly 90 is in a cartridge type format that is removably mated to handle body 30; however, this is not required in all embodiments. Instead, the soldering tip assembly 90 may be of a type that is not intended to be removable by the user. For example, the soldering tip assembly 90 may be permanently attached to the handle body 30, such as by being partially embedded therein.
The prongs 26 of power supply 22 may be arranged in a single permanent configuration (e.g., a two or three-prong arrangement conventional in the US), or the power supply 22 may be equipped with interchangeable prongs so as to be adaptable to different outlet plug configurations (e.g., in different countries). Alternatively, the power supply 22 may be connected to an electrical outlet via a transformer cord (not shown), but such is believed less advantageous. Further, while
The power supply 22 advantageously supplies power to the heating element 102 at a controlled (or “regulated”) low voltage irrespective of a temperature of the soldering tip 100. The temperature of the soldering tip 100 is thus determined in an open loop fashion, without a control feedback from a thermocouple or equivalent. Instead, the voltage fed to the heating element 102 from the power supply 22 is controlled to be at a predetermined setpoint (e.g., at 9.0 volts DC), and not varied based on a sensed temperature of the soldering tip 100. In most embodiments, this setpoint cannot be varied by the user.
Further, the discussion above has assumed that the on/off state of the soldering iron 20 is controlled by an on/off switch 50; however, such is not required in all embodiments. Indeed, in some embodiments of the soldering iron 20 may not include an on/off switch 50, and the on/off state of the soldering iron 20 may be controlled by the user plugging or unplugging in the transformer 22 into an electrical outlet.
The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. Further, the various aspects of the disclosed device and method may be used alone or in any combination, as is desired. The disclosed embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
