Two-circuit grip heater

Abstract

A grip heater has a tubular insulator that is designed to slip over a handlebar and has two interposed pairs of helical recesses. Each pair of helical recesses is formed by two parallel helical grooves and accommodates a heating element; the heating elements can have different resistances to provide differing degrees of heat when selectively connected to a voltage source. Preferably, the pairs of recesses overlap such that the heating elements reside in alternating grooves and cross over each other. The heating elements can be connected to a common ground to allow replacement of existing three-wire grip heaters. When a common ground is employed, the heating elements are preferably isolated where they cross.

Description

BACKGROUND OF THE INVENTION [0001] Grip heaters are employed to heat the hand grips of motorcycles, snowmobiles, and similar equipment which are operated in cold weather but which require sufficient dexterity on the part of the user to make the wearing of bulky mittens or gloves impractical. Such grip heaters are particularly beneficial in alleviating the effect of wind chill, especially when used on vehicle handgrips. These grip heaters have an electrical heating element which is embedded in the handgrip and is powered by a voltage supply of the equipment, such as a battery or a magneto. Examples of such grip heaters are taught in U.S. Pat. Nos. 4,471,209; 4,937,429; and 4,990,753 of the present inventor. These grip heaters have a single heating element of resistive wire wrapped over a tubular insulator having a pair of helical recesses in which the heating element resides. This structure is subsequently covered with a soft grippable material such as rubber to form a composite grip...

AI Technical Summary

Benefits of technology

[0009] Similarly, a second heating element is provided, which resides in the second pair of helical recesses along the central region of the tubular insulator, and which terminates in a second element first end and a second element second end, both located in close proximity to the base end region of the tubular insulator. Means for transferring the second heating element from the third helical groove to the fourth helical groove in close proximity to the distal end region of the tubular insulator are provided and provide a similar function for the second heating element as the means for transferring the first heating element. Again, when the second heating element is so positioned, it can be readily connected to the voltage source to provide heating since the second element ends will be conveniently located at or near the base end region of the tubular insulator.

[0011] When the second pair of helical recesses are interposed between the first pair of helical recesses such that the grooves of the helical recesses alternate along the length of the grip (the overlapping helical relationship), the spacing between the grooves can be increased, since either the first heating element or the second heating element can be energized without creating unheated regions of significant length which could create uncomfortable cold spots. Furthermore, if one of the heating elements is energized, there will be a non-energized coil between each of the coils of the energized heating element, which will provide a region in which excess heat can be dissipated. While the overlapping relationship of the helical recesses offers many benefits, this pattern of grooves requires the first heating element and the second heating element to cross each other in the region where one of the heating elements crosses over from one helical groove to another. In the event that the two heating elements are independently powered, this crossover does not create a problem. However, if the heating elements share electrical contacts to the power source, such as a common ground connection, then it is generally preferred to maintain electrical isolation of the two heating elements where they cross. This will require that, in addition to the means for transferring the first heating element and the means for transferring the second heating element, there will need to be means for isolating the heating elements. This isolation can be provided by protrusions and / or grooves on the tubular insulator, which can also aid in maintaining each heating element in tension as it is wrapped into the helical grooves in which it is to reside. An alternative means is to place an insulating material between the heating elements where they cross.

[0014] To simplify the circuitry and to provide a grip which is suitable to retrofit many of the conventional circuits in service, it is preferred for the heating elements to be connected together at their unswitched ends to provide a common ground. As discussed above, if such is done, it is preferred to provide not only means for transferring the first heating element and the means for transferring the second heating element, but also provide means to prevent contact between the first heating element and the second heating element at the crossover points on the tubular insulator.

Problems solved by technology

Grip heaters are employed to heat the hand grips of motorcycles, snowmobiles, and similar equipment which are operated in cold weather but which require sufficient dexterity on the part of the user to make the wearing of bulky mittens or gloves impractical.

The printed circuits maintain reasonable grip thickness since the conductors are thin and flat; however, these conductors tend to break down at one or more locations along the conduction during use.

These breakdowns may result from damage to the printed circuits due, in part, to mechanical straining of the circuit by the user applying force or torque to the grip to maneuver the device to which it is attached.

The mechanical strains introduce irregularities which in turn causes the temperature to spike, causing local deterioration of the circuit and ultimately failure; this limits the useful life of such devices.

Two additional problems that have been found in printed circuit grip heaters are delamination and heat loss.

Over time, the circuit substrate delaminates from the underlying structure, apparently due to thermal degradation of the laminating adhesive, again reducing the life of the grip.

The printed circuit also results in excessive heat loss since it resides in close proximity to a metal handlebar and employs flat conductors wrapped around the handlebar, which will increase heat radiation toward the handlebar.

The '572 patent does not disclose how the individual heating coils are connected to form a circuit, thus raising the issue of whether the '572 patent provides an enabling disclosure.

A limitation of such grip heaters is that they depend on the central metal sleeve and metal handlebar to complete the electrical circuit, and thus cannot be used on equipment which has handlebars that are electrically insulated from the battery.

Additionally, the metal sleeve tends to act as a heat sink, drawing heat towards the metal handlebars.

The inclusion of a resistor complicates the wiring and results in wasted electrical power output.

Furthermore, the resistor must be fairly large to dissipate a large amount of energy and must be mounted in an exposed location to allow the heat to be dissipated, complicating installation of the grip heater.

This approach requires complicated circuitry to switch the current on and off.

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