Refrigeration – Using electrical or magnetic effect – Thermoelectric; e.g. – peltier effect
Reexamination Certificate
2000-01-18
2001-10-02
Tapolcal, William E. (Department: 3744)
Refrigeration
Using electrical or magnetic effect
Thermoelectric; e.g., peltier effect
C062S003500
Reexamination Certificate
active
06295819
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to thermoelectric heating and cooling devices. More particularly, the invention relates to a thermoelectric heat pump fluid circuit for alternately delivering hot and cold fluids to a therapeutic heat pad, wrap, or other device.
2. Description of the Prior Art
Many devices and objects must be alternately heated and cooled during their use, manufacture, or maintenance. For example, in sports therapy, it is common to treat injured patients by alternately applying heat and cold to the injuries in a cyclic fashion via a heat pad or wrap. This procedure is commonly referred to as contrast therapy and is considered to be effective in reducing the healing time of an injury. To achieve the best therapeutic results with contrast therapy, it is beneficial to rapidly switch between application of heat and cold and to accurately control the temperature, time and other parameters relating to the treatment.
Prior art devices have been developed to alternately deliver hot and cold fluids to an end device for heating and cooling the end device. These prior art devices typically use thermoelectric heat pumps for heating and cooling the fluid delivered to the end device. Switching from heating to cooling (or vice versa) is accomplished by electrically reversing the polarity of power applied to the heat pump. This causes the hot side of the heat pump to become cold or the cold side to become hot to change the temperature of the fluid passing thereby before it is delivered to the end device. Unfortunately, the thermal mass of the heat pump slows the transition between heating and cooling modes after the polarity of the power has been reversed and therefore significantly limits the cycling speed of these prior art devices.
Electrically switching a heat pump between heating and cooling modes to alternately heat and cool an end device also wastes the heat present on the hot side of the heat pump when it is switched to a cooling mode and wastes the cool produced on the cold side of the heat pump when it is switched to a heating mode. This reduces the efficiency and therefore increases the operating costs of these prior art devices, especially when the devices must be frequently switched between heating and cooling modes as is done in contrast therapy.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention solves the above-described problems and provides distinct advance in the art of thermoelectric heat pump devices used for contrast therapy and other applications. More particularly, the present invention provides a thermoelectric heat pump fluid circuit that can rapidly cycle between the delivery of hot and cold fluids to an end device such as a therapeutic wrap or pad and that significantly reduces the amount of thermal energy that is wasted during the operation thereof.
The apparatus of the present invention broadly includes a heat pump, a fluid circuit coupled with the heat pump and having a fluid contained therein, a pump interposed in the fluid circuit for circulating the fluid therein, and a valve interposed in the fluid circuit for selectively delivering fluid from the fluid circuit to an end device coupled with the apparatus such as a therapeutic pad or wrap. The heat pump has both a heating junction and a cooling junction. The fluid circuit includes a hot channel that passes by the heating junction of the heat pump and a cold channel that passes by the cooling junction of the heat pump. The valve is interposed in the fluid circuit between the hot channel and the cold channel and can be operated to selectively deliver either heated fluid or chilled fluid to the end device.
Alternating between the delivery of heated and chilled fluid to the end device does not require switching of the polarity of power delivered to the heat pump. Instead, the polarity of power delivered to the heat pump remains constant in the present invention so that the heating junction of the heat pump always stays hot and the cooling junction always stays cold. The apparatus of the present invention alternates between heating and cooling modes by mechanically changing the flow direction of the fluid in the fluid circuit. Specifically, when it is desired to heat the end device, the valve is operated to direct hot fluid that has just passed over the heating junction of the heat pump to the end device and to recirculate the returning fluid. Similarly, when it is desired to cool the end device, the valve is operated to deliver chilled fluid that has just passed over the cooling junction of the heat pump to the end device and to recirculate the returning fluid.
The apparatus of the present invention provides numerous advantages. For example, because the heating junction of the heat pump always stays hot and the cooling junction always stays cold, the thermal mass of the heat pump does not influence the transition between heating and cooling modes. Therefore, the apparatus of the present invention can rapidly cycle between heating and cooling modes. Moreover, the thermal energy produced by the heat pump is not wasted during cycling between heating and cooling modes of operation.
These and other important aspects of the present invention are described more fully in the detailed description below.
REFERENCES:
patent: 4601587 (1986-07-01), Mathiprakasam
patent: 4634803 (1987-01-01), Mathiprakasam
patent: 5562604 (1996-10-01), Yablon et al.
patent: 5711155 (1998-01-01), DeVilbiss et al.
Heenan Patrick J.
Mathiprakasam Balakrishnan
Ali Mohammad M
Hovey Williams Timmons & Collins
Midwest Research Institute
Tapolcal William E.
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