US20080178631A1

US20080178631A1 - Recreational vehicle refrigerator efficiency device

Info

Publication number: US20080178631A1
Application number: US11/657,745
Authority: US
Inventors: Stuart Scott Snyder
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-01-25
Filing date: 2007-01-25
Publication date: 2008-07-31

Abstract

An Electric device which improves Efficiency during warm weather in ammonia type refrigerators found in recreational vehicles. The system operates automatically to turn on a blower to dissipate heat from the refrigerator's condenser, and turns off automatically when the refrigerator is not being used, or when the refrigerator's thermostat cycles off.

Description

The present invention relates to a recreational vehicle refrigerator efficiency device. The device consists of the following components:

- A sheet metal or plastic funnel that sits directly below condenser coils to guide air thru condenser
- A 12 volt box fan to create airflow, which is mounted in the opening of funnel
- A thermostat mounted on the boiler tube right before condenser, that turns the fan on and off.

BACKGROUND OF INVENTION

Since the attacks on our country on Sep. 11, 2001, many Americans have purchased RV'S as an alternative for vacations instead of flying. Most of these RV'S have kitchens with refrigerators installed in them. These refrigerators are the ammonia absorption type. These units are reliable, being in existence for decades. They have no moving parts, and are powered by 110 volt house current, LP gas, and or 12 volt DC.
A drawback, however, is these units depend on ambient air temperature to operate. The higher the outside temperature, the less efficient the unit will operate. This is caused by the condenser not being able to convert the vapor ammonia supplied by the boiler entirely into a liquid. The result is a cold freezer, but the refrigerator section being warm, because there is not enough liquid ammonia being produced to keep the refrigerator section cold, resulting in spoiled food.
These refrigerators are installed in a compartment inside the RV. Most applications have a vent thru the roof, and also a louvered door outside the RV, at the bottom of the refrigerator compartment. Natural draft occurs as cool air enters the lower louvered door and travels up behind the refrigerator, passes across condenser, removes heat from condenser, and in most applications, exits thru the roof vent, although some applications have an upper side vent instead of a roof vent.
During hot seasons, there is a need to force air thru the condenser to convert the vapor ammonia into as much liquid as possible. Applicant is aware of devices on the market to move air around inside the refrigerator cavity, but none of these devices actually force air directly thru the condenser, where it is needed.
Applicant investigated the patent literature on this topic and the following patents turned up during the course of a search:

- U.S. Pat. No. 2,562,286 M. R. Wall
- U.S. Pat. No. 2,705,404 H. S. Malutich
- U.S. Pat. No. 2,734,441 E. C. Williams
- U.S. Pat. No. 3,444,698 J. L. Lorenz
- U.S. Pat. No. 3,717,010 Slattery
- U.S. Pat. No. 4,864,269 Priebe
- U.S. Pat. No. 5,228,307 Koce
- U.S. Pat. No. 5,355,693 McConnell et al
- U.S. Pat. No. 6,076,363 John C. Morton

None of these patents either singly or in combination anticipates or renders obvious the subject matter of this invention. It is an object therefore to provide an automatic system that forces air thru the condenser coils when unit needs to produce more liquid ammonia. It is another object to provide a system that is universally retrofittable to existing RV refrigerators. Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the device possessing the features properties and the relation of components which are exemplified in the following detailed disclosure and the scope of the application of which will be indicated in the appended claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cutaway view of a refrigerator compartment in a typical RV, with the refrigerator therein, and the elements of this invention relative to the rear of the RV refrigerator.

FIG. 2 is a view of the invention with electrical components and wiring.

FIG. 3 is a side view of invention, relative to the rear of refrigerator.

SUMMARY OF THE INVENTION

A system comprising of a plenum with a high cubic feet per minute fan forcing air directly thru the condenser of a RV refrigerator to dissipate heat to increase efficiency.
The system operates automatically to turn on and off as needed, regulated by boiler temperature. The system ceases to function when the refrigerator itself is turned off, or when the thermostat in the refrigerator is not calling for cooling. By forcing air thru the condenser, which is a heat transfer device, allows the condenser to dissipate more heat, thereby allowing the vapor ammonia to fully turn back into a liquid, thereby increasing the cooling capacity of the refrigerator.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 there is seen a typical RV refrigerator, 1 which can vary in cubic size. No matter the size, they all generally operate in the same manner. That is they are powered by 110 volt house current at a RV park, or in remote areas off of 12 volt DC or LP gas.
Refrigerator is seen disposed within a compartment 4. The compartment has a spaced rear wall, and this is where the natural draft occurs to cool the condenser 7. Cool air enters lower louvered door 2 and warm air exits thru upper side louver 3 or more commonly out the roof vent 16. On very hot days the same draft occurs, but since the air temperature is higher the condenser 7 can not cool down the hot ammonia vapor totally, thus not supplying the refrigerator with enough liquid ammonia. Since the refrigerator compartment is 2^ndin line to the freezer compartment, the refrigerator coils 14 have no liquid ammonia going into them, resulting in no cooling.
To prevent this occurrence, condenser 15 is fitted with a plenum constructed of thin gauge sheet metal or molded plastic 9 with a high cubic feet per minute box fan 8 mounted on bottom of plenum. Plenum is slid behind condenser coils 7 and attaches to rear of refrigerator via 2-way tape and optional stand off bracket 17. A snap disc thermostat 11 is mounted on vapor line coming out of boiler 5. Snap disc thermostat 11 closes on temperature rise and opens on temperature fall. When boiler 5 tube reaches a predetermined temperature, the snap disk thermostat closes and sends 12-volt DC positive current from factory junction box 6 on rear of refrigerator to the 12-volt DC positive line 12 of box fan 8. The negative 12-volt DC line 13 is attached to the 12-volt DC negative line of box fan 8 and to the factory junction box 6 on rear of refrigerator and is not switched in any form. At this point the fan starts and pulls air from lower louvered door 2 and forces it thru plenum 9 and condenser 7 and exits out upper louvered panel 3 or more commonly out roof vent 16.
When the thermostat in refrigerator is satisfied and not calling for any cooling, or the refrigerator is shut off, the boiler 5 ceases to heat and the boiler 5 vapor line cools, and the snap disk thermostat 11 opens, thereby breaking the 12-volt DC positive current 12 to box fan 8.
It is seen that there is nothing to set, nothing to forget. All one needs to do is to turn on the refrigerator and the invention will turn on automatically as needed.
In the event the snap disk thermostat 11 or box fan 8 fail, unit will still operate, but will operate as if the invention was never installed, meaning no gain in efficiency.
The snap disk thermostat and box fan mentioned above are readily available in the marketplace from several venders. Electrical current consumption of the box fan is small, as it would take weeks of constant running to drain a RV deep cycle battery.
It is seen that I have developed a system where air is forced directly thru the condenser coils of a RV refrigerator to improve efficiency during high temperature seasons, without the need to remember to turn the system on or off.
I have several prototypes operating in the field, and a 30% increase in efficiency was noted.
Since certain changes may be made in the above device without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description, shall be interpreted as illustrative and not in a limiting sense.

Claims

1. An automatic switch controlled device which forces air via a box fan and plenum directly thru the condenser coils of a RV refrigerator, improving efficiency during hot seasons.

2. The method of evacuating heat generated from the operation of a RV refrigerator's condenser from the space between the refrigerator and the outside wall of the vehicle which comprises: Mounting a plenum and box fan to the condenser of refrigerator, and a snap disc thermostat to boiler tube, and using existing factory power point, automatically actuating the fan when said snap disk thermostat senses a rise in boiler tube temperature, and automatically turning off when said snap disk thermostat senses a fall in boiler tube temperature.

3. A universal device that is easily adaptable to existing RV refrigerators.