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The Double Bubble Wheel Engine

To understand the invention it is best to first understand its elements. Figure 1 shows a ring of 6 divers. The water level is indicated. The ports on top of each diver are open - the ring is horizontal and the water reaches the same level in each diver.  If the ring is slowly rotated the water remains at essentially the same level in each diver.  In Figure 2, the ring is shown tilted. The water has shifted to a new level, almost filling some of the divers at the low side and almost absent from the divers at the high side.  If the ring is rotated in this position water alternately fills and empties individual divers.  For instance as diver No. 1 moves towards the position of No. 3, it fills with water and as it continues on past the position of No. 3, it empties. The open ports allow air to enter as a diver empties and air to leave as a diver fills.

The ring is returned to the position of Figure 1 and corks are inserted into the ports preventing air from entering or leaving. Figure 3 shows the ring again tilted on its side. This time the water is at many different levels. The air captured in the lower divers prevents all the water from running into the lower divers. The size of the air bubbles in each diver may be approximately the same. The lower bubbles are somewhat smaller since the density of liquid multiplied by the difference in elevation between the level in diver No. 1 and No. 4 now compresses No. 4.

If the ring is rotated in this position there is a slight flow of water into the divers as they sink and out of the divers as they rise. The magnitude is a function of the ring diameter, fluid density, and gas pressure in the bubbles.

In Figure 4 two rings are placed on the same vertical axis. Diver No. 1 above diver No. 7. Their ports are now connected by a tube so that an air passageway exists between No. 1 and No. 7, but No. 1 and No. 7 are not connected to the outside atmosphere. Similarly for No. 2 and 8, 3 and 9, etc.

If the pair of so-connected rings is tilted as in Figure 5, the water assumes levels similar to the situation in Figure 3, but the relative liquid levels in the top ring are essentially the same as in the bottom ring. The gas pressure resisting the inflow of the water is the same in No. 1 as in No. 7.

When the pair of rings is rotated there is a compression of the gas and inflow of liquid at the bottom of the cycle - similar to that described in Figure 3. The resemblance of Figures 5 and 3 is true only so long as the connected divers are in the same angular position on the axle.

Figure 6 shows the two rings with the relative positions rotated 60 - lower than No. 1. The water levels in No. 1 and No. 7 were identical. As No. 7 is lowered the pressure from the liquid increases and the bubble rises through the tube into diver No. 1 leaving diver No. 7 largely filled with liquid and diver No. 1 largely filled with air.  Rotating the pair of so-attached rings causes the air bubbles to move always towards the relatively higher of the connected divers - consequently the air is equally divided between the two connected divers every 180 as they come to the top and bottom position and is largely held by each diver for a period once every 360.  If the two rings are at the same temperature, there is very little resistance to turning in either direction because if the two rings are at the same temperature, the bubbles descending in one ring are the same size as the bubbles ascending in the other ring and there is no resulting turning force.

However if one of the rings is warmer than the other, the bubbles in the warm divers tend to expand more than the bubbles in the cold divers, with a resulting turning force that rotates the pair of rings such that the warm bubbles rise and the cold bubbles sink.

Patent Summary

The invention is a device for converting thermal energy into mechanical energy.  Pairs of chambers (divers), one hot and one cold are connected with an intermediate regenerator so that a bubble of gas may pass from hot diver to cold diver through the regenerator. The divers are arranged about an axle so that as the engine turns the bubbles pass from hot to cold to hot divers. The alternating expansion and contraction of the bubbles keeps the majority of liquid always on one side of the axle. The imbalance causes the engine to turn in a gravitational or centrifugal field. The cycle that powers the engine depends on the liquid, or liquids in the engine and the gas or gases in the bubble. A liquid with a relatively low vapor pressure, such as a low viscosity oil, and a high pressure bubble of a gas different than the vapor of the liquid, such as air, causes a cycle similar to that of a Stirling engine. A liquid with a relatively high vapor pressure, such as water, and a relatively low pressure of gas different than the vapor of the liquid, such as air, causes a cycle like that of a Rankine engine.

One object of the invention Is to build a device that can economically use a variety of heat sources, such as burning fuel, solar energy, or waste heat from other applications. Another objective of the invention is to build a device that moves as one part, but which is capable of collecting and storing heat and cold for its own operation.  A further objective of the invention is to build a device that can easily be used as a heat pump or refrigerator.  It is obvious that the engine, or multiples of the engine, can be arranged so that they spin about their own axes. They rotate the arrangement about an external axis so as to create a centrifugal field to increase the power output.


The problem with these engines is their relatively low power compared with their volume and weight.   (See Stilling Cycle Machines, G. Walker, Clarendon Press, Oxford, 1973.)  The engine shown in the photograph weighs about 80 lbs. and yet we have only coaxed about 1/3 of a watt from it. This is the
first engine built and I believe we can increase the power to weight ratio. The first version had the rings connecting the divers made of 3/4" copper pipe. The small pipe restricted the flow of water from diver to diver and the engine exhausted itself by fluid friction at a very low r.p.m.