Solar-powered temperature regulation system for the interior of an automobile/motor vehicle

Abstract

A temperature regulation system, which can be used to cool the interior temperature of an automobile/motor vehicle, when it is parked under the sun, substantially below the external temperature, was designed and produced. The system was powered by solar cells, thus functioning without dissipating any energy from the vehicle's battery. The mechanical device of the system incorporated Peltier elements, heat sinks and fans, all controlled by a power supply in the form of a circuit board. When the automobile was switched on, the system could be further used as an automobile climate control unit, for heating or cooling, withdrawing the supplementary electricity from the battery, another feature controlled by the circuit board.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

US Patent Documents
4,280,330	July 1981	Harris et al.
4,658,597	April 1987	Shum
4,658,599	April 1987	Kajiwara
4,955,203	September 1990	Sundhar
5,205,781	April 1993	Kanno et al.
5,233,227	August 1993	Kajimoto et al.
5,588,909	December 1996	Ferng
5,687,573	November 1997	Shih
5,826,435	October 1998	Hange
6,662,572	December 2003	Howard

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

Not applicable

FIELD OF THE INVENTION

The invention relates to a temperature regulation system for the interior of an automobile/motor vehicle and, in particular, to a cooling system for the interior of a parked vehicle.

BACKGROUND OF THE INVENTION

Thermoelectric modules are solid-state devices (no moving parts) that convert electrical energy into a temperature gradient known as the “Peltier effect” or convert thermal energy from a temperature gradient into electrical energy, the “Seebeck effect”. Although thermoelectric(TE) modules used as thermoelectric generators are rather inefficient, they may be used as thermocouples for temperature measurements. That is the thermoelectric module, or Peltier element, can function as a heat pump. When the appropriate power is applied from a battery or another DC source, one side of the element will become cold while the other will become hot. (Reversing the polarity through the element will make the cold side hot and hot side, cold.) This provides Peltier elements to be very useful for heating, cooling and temperature stabilisation.

From the Second Law of Thermodynamics, it is known that heat will move to a cooler area. Hence, the Peltier element will absorb heat on the “cold side” and eject it out the “hot side” to a heat sink. In addition to the heat being removed from the object being cooled, the heat sink must be capable of dissipating the electrical power applied to the element, which also exists through its hot side. It is well known that the resistive or “Joule heat” created is proportional to the square of the current applied. With Peltier elements, this is not the case because the heat created is actually proportional to the current since the flow of current is working in two directions (the Peltier effect). Therefore, the total heat ejected by the Peltier element is the sum of the current times the voltage plus the heat being pumped through the cold side. The cooler the hot side of the Peltier element, the cooler the cold side will be. When power is applied to the element, the hot side will begin ejecting this as heat to the heat sink causing it to rise in temperature. The ability of the heat sink to dissipate this heat as well as the heat being pumped through the cold side will determine the actual operating temperature of the hot side and, thus, the cold side.

In general, the most common type of heat sink used in thermoelectric applications is made from a thermally conductive material such as aluminum or copper with fins which are perpendicular to a base. In TE applications, however, a heat sink alone is not able to remove a sufficient amount of heat by natural convection in order to keep the hot side at an acceptably low temperature. To help the heat sink remove heat on and around the heat sink fins, a fan must be attached which forces ambient air over the fins and exhausts the heat to ambient.

Previously, it was mentioned that Peltier elements operate using a DC power source. Solar cells are photovoltaic (PV) cells which can convert sunlight directly into electricity. PV cells are made of semiconductors, such as silicon. When sunlight strikes the cell, a certain portion of it is absorbed within the semiconductor material, i.e. silicon, because the energy needed to ionise a silicon electron matches the typical energy of photons coming from the sun. The energy of the absorbed light is transferred to the semiconductor, knocking electrons loose and allowing them to flow freely.

PV cells have one or more electric fields which act to force electrons freed by light absorption to flow in a certain direction. This flow of electrons is a current and, by placing metal contacts on the top and bottom of the PV cell, one can draw that current off to use externally. This current along with the cell's voltage (which is a result of its built-in electric field or fields) defines the power that the solar cell can produce. Moreover, it is a direct current since the flow of electrons is in one direction.

It is very well-known that, when an automobile/motor vehicle is parked under the sun, the interior becomes very hot. From the prior art, a number of attempts has been made to control the interior temperature of vehicles, especially, from the heat of the sun. In U.S. Pat. Nos. 4,280,330 and 5,687,573, battery operated heating and cooling are obtained by Peltier elements. In U.S. Pat. Nos. 4,658,597 and 4,658,599, solar energy is used in conjunction with particular types of coolant systems. In U.S. Pat. Nos. 5,205,781, 5,233,227 and 5,588,909, solar energy is employed to activate ventilators and, in U.S. Pat. No. 5,826,435, a portable ‘energy efficient’ air conditioner is powered by solar energy. Definitely, all these devices have their advantages and disadvantages. One deficency of some of these devices appears to be the extensive mechanical modifications necessary in the vehicle. Another deficency of some others seems to be that the best attainable inside temperature would only be as low as the outside temperature, if that at all. (This still may be very high in certain geographical locations.) Moreover, some devices still use an environmental pollutant, namely a coolant.

When the sun is shining on those rare days in winter time, the interior of an automobile becomes comfortably warm compared to the outside environment. Upon entering the vehicle, a driver or a passenger does not require a system which heats the interior. That driver or passenger will require a system which heats the interior when the sun is not shining because the interior will be cold when he enters the vehicle. However, under such circumstances, a solar powered heating system would not be very efficient because there would be very little solar energy available. Although the interior of an automobile becomes warm during summer time when the sun is not shining on those rare days, it does not become unbearably hot compared to when the sun is shining. Accordingly, it is really just necessary to develop a system which cools the interior of a vehicle when the sun is shining in summer time. If that same system can also heat with or without the aid of solar energy, then it would have a broader function, particularly, in winter time.

There were two attempts which coalesced the two above-mentioned technologies, i.e. the Peltier effect and solar energy, to yield satisfactory, sufficient and reasonable quantities of coldness. These were disclosed in U.S. Pat. Nos. 4,955,203 and 6,662,572. In U.S. Pat. No. 6,662,572, there were two criticisms of the approach undertaken in U.S. Pat. No. 4,955,203, namely, of premanently installing the system within the vehicle and mounting the solar panels within the interior of the passenger compartment. In U.S. Pat. No. 6,662,572, the climate control unit sits on top of a partially opened window and the solar panel is ‘removably attachable’ to the roof In spite of the fact that the efficiency of the solar panel is diminished when it is mounted inside the vehicle, it would be very difficult that it can be damaged by sudden changes in weather or by flying debris. More probable, the presence of the removably attachable solar panel on the roof renders it more susceptible to theft and, considering that the solar panel is the most expensive part of the climate control system, this is a major concern. Additionally with a removable unit, the driver or someone must manually place the climate control unit on the window and unfold the solar panel on top of the roof when the automobile is parked. Hence, portability and detachability are not attractive features of such a system.

In U.S. Pat. No. 4,955,203, the general concept of designing an ‘installed’ solar powered thermoelectric cooling system was particularly noteworthy. Nevertheless, that design had some drawbacks which are overcome in the present design. For example, since the cooling unit was placed in the trunk the vehicle required substantial mechanical modifications.

BRIEF SUMMARY OF THE INVENTION

The temperature regulation system consists of photovoltaic cells, a power supply, and an open ended mechanical unit having sides for supporting a heat pump. The photovoltaic cells can be comprised of solar cells attached one to another for generating energy. The solar cells can be connected to the power supply which controls the distribution of energy and the interaction between the system and the vehicle. The power supply can also activate the heat pump, such as a Peltier element. On at least one side of the mechanical unit, openings can be provided to accommodate one or more Peltier elements, having an inner surface and an outer surface. Each surface of a Peltier element can be attached to a heat sink, one providing the cold source and the other providing the hot source. At one end of the mechanical unit, a main fan can be installed to thrust air across the cold surface (or hot surface, if the polarity is reversed) for passage through the opposite end and into the interior of the vehicle. Additional fans can be placed on top of the heat sinks to dissipate heat from the hot source (or cold source, if the polarity is reversed). Accordingly, in various embodiments, the power supply can be an electronic control unit, such as a printed circuit board, and the mechanical unit can be a tubular body.

Other aspects and features of the present invention will become apparent, to those ordinarily skilled in the art, upon review of the following description of the specific embodiments of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will be described in greater detail with reference to the accompanying diagrams, in which:

FIG. 1 is a block diagram of the temperature regulation system.

FIG. 2 is the top of a perspective view of the tubular body.

FIG. 3 is a cross-sectional view of the tubular body.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, the temperature regulation system is illustrated as a block diagram. In this specific case, it is comprised of solar cells, 1, connected to an electronic control unit, 2, which distributes the electricity coming from the solar cells to the various parts of the mechanical unit, i.e. the two types of fans, 3 & 6, and the stage one Peltier elements, 4, when the automobile is parked. A certain number of Peltier elements (for example, 2) works very well to lower the temperature, substantially below the outside temperature, of the interior of an automobile when it is parked. By using a reasonable number of solar cells, the power coming from them is sufficient to activate approximately 50% to 60% of the elements' capacity. When the number of Peltier elements is increased (for example, 4) and the automobile is switched on, the interior temperature of the automobile is significantly reduced. The electronic control unit withdraws the extra needed electricity from the battery, 7, for the supplementary energy for the stage 1 Peltier elements, 4, and the activation of the stage 2 Peltier elements, 5, to function at maximum capacity.

The electronic control unit also had a temperature regulator, (FIG. 1, 8) to control the interior temperature, when the automobile is running, and a switch to turn off the system completely, when a sensor (FIG. 1, 9) detected high levels of carbon monoxide. Moreover, the electronic control unit had a safety feature when the carbon monoxide sensor switched off the fans or when either heating or cooling the interior of the automobile was not a priority but yet a great deal of sunlight was prevalent. Under such circumstances, solar energy should be consumed one way or another because, if it is not, the stored energy in the solar cells coming from the sunlight would destroy them. In order to dissipate the unused energy, the electronic control unit re-directs this unused energy to charge the battery.

FIG. 2 is the top view of a perspective drawing of a specific design of the mechanical unit and FIG. 3 is a schematic drawing of the cross section of that design illustrating the inside of the unit. The unit contains Peltier elements, 4 & 5, two types of fans, 3 & 6, heat sinks, 10, and a carbon monoxide sensor, 9. It is comprised of a tubular body (basically, a housing) with Peltier elements on one or either side integrated into the side wall(s). In the case of cooling, the hot side of the Peltier elements is on the outer side and the heat sinks lie on top of them. In the present embodiment, the fans, 6 (only one fan is showing in FIG. 2 to demonstrate the stacking of the components), are attached to the top of the heat sinks in order to direct air along the outside of the housing, i.e. to remove the heat from the hot side and lower the temperature of the cold side. The cold side of the Peltier elements is on the inside of the housing and also has heat sinks attached to them. However, on the inside of the housing where the coldness exists, there is a major fan, 3, at one open end to direct air through the inside of the tubular body, i.e. to flush and expel the coldness out the opposite open end. Since the housing would be installed preferably in the front of the vehicle behind the grill and next to the radiator, or possibly any available space under the hood if there is no space in the very front, the open end is then attached simply to the ventilation system via a tube.

Ideally, the solar cells would be placed in between the two panes of glass which make up the front or back windshield or alternatively in the sunroof windshield, if such exists. For the present purposes, however, an UV-resistant and heat-resistant plastic frame for two 2V solar cells was produced. Six solar cells were connected in series to yield 12 volts and then 2 or 3 sets of six in parallel to generate just enough current for two, three or more Peltier elements, depending on the volume of the passenger compartment, needed to lower the interior temperature of the vehicle substantially below the exterior temperature. Since the frames were designed with a width of approximately 51 mm, they were placed along the top of the front windshield and/or the bottom of the back windshield with suction cups. These two positions rendered the absorption of sufficient solar energy and yet had little or no affect on obscuring the visibility of the driver.

What has been described is merely illustrative of the application of the principles of the invention. Other arrangements and methods can be implemented by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A temperature regulation system comprising:

a tubular body having a side wall and open ends arranged to permit flow through the tubular body;

at least one heat pump integrated into the side wall of the tubular body, the at least one heat pump operable to establish a temperature difference between the inside and outside of the tubular body; and

a power supply connection coupled to provide power to the at least one heat pump.

2. A temperature regulation system according to claim 1 further comprising at least one set of photovoltaic cells connectable to the power supply connection.

3. A temperature regulation system according to claim 1 further comprising at least one electrochemical cell connectable to the power supply connection.

4. A temperature regulation system according to claim 1 further comprising an air flow system of at least one fan for directing air through the inside of the tubular body.

5. A temperature regulation system according to claim 1 further comprising an air flow system of at least one fan for directing air along the outside of the tubular body.

6. A temperature regulation system according to claim 1, wherein the at least one heat pump is a Peltier element, the Peltier element having first and second broad surfaces, the first broad surface facing outside the tubular body and the second broad surface facing inside the tubular body.

7. A temperature regulation system according to claim 6 further comprising a pair of heat sinks arranged, wherein one of the pair is on one side of the Peltier element and the second of the pair is on the other side of the Peltier element.

8. A temperature regulation system according to claim 7, wherein the pair of heat sinks is one of aluminum, copper, nickel or an alloyed metal material.

9. A temperature regulation system according to claim 1 further comprising a regulator operable to control the temperature difference.

10. A temperature regulation system according to claim 1 further comprising a sensor operable to detect different levels of carbon monoxide.