1. Field of Invention
The present invention relates to a warmer, and more particularly to a portable warmer, wherein a warmer bag is received in a casing to safely warm up the heat exchanging fluid in the warmer bag through a safety arrangement such that when the heat exchanging fluid is heated above an usable temperature, the safety arrangement automatically cuts off an electrical connection between the heating element and the external power source for preventing the heat exchanging fluid from being overheated.
2. Description of Related Arts
During winter time, most people would like to use some warmer apparatus, such as electric heaters, in order to keep themselves warm. However, such warmer apparatus requires an electric power and has a relatively bulky size that the user cannot carry the warmer apparatus everywhere.
One kind of small and portable heating device, called warm water bag comprises a sealing bag, which is made of waterproof material such as plastic, having an inner cavity and an opening. In order to use the water bag, the user has to fill up the hot water into the inner cavity of the bag. Therefore, the user is able to hold the water bag close to the body of the user. In other words, the water inside the cavity gradually dispenses its heat through the sealing bag, so that the user can put the water bag to part of body, such as hands or feet, to keep himself or herself warm.
An improved water bag is made that the water bag is adapted to be placed in a microwave oven to heat up the water inside the water bag. Likewise, a built-in heating element is mounted into the water bag to heat up the water inside the water bag.
However, the traditional water bag is inconvenient for people to use. Since the hot water is gradually cooling down in a timely manner, the water bag cannot provide the warming ability after a short period of time. Then, the user must pour out the water inside the sealing bag and refill the hot water. In other words, the user must repeatedly refill the hot water frequently, which is very inefficient and inconvenient.
In the other hand, it is convenient for the user to heat up the water inside the sealing bag by microwave oven. However, it is relatively dangerous for the user when the water inside the sealing bag is overheated. Accordingly, few seconds of contacting with the hot water will cause a serious burn. The overheated water inside the sealing bag will also cause a serious explosion.
Likewise, by electrically connecting the heating element with the external power source, the water inside the sealing bag can be gently heated up by the heating element. However, when the water is heated, the volume of the water is expanded. When the water expands at a predetermined volume larger than the capacity of the sealing bag, the sealing bag will be forced to be popped and the hot water will be leaked from the sealing bag. Since the heating element is electrically connected to the power source, the hot water leaking from the sealing bag may cause an electrical short circuit or even a serious electric shock to the user. In other words, the user needs to find more secure and safe way to keep warm by using the water bag.