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Stirling Engine, Rider Patents
The Rider engine uses the Stirling engine principle to run. Air inside the cylinder is heated to expand it, then cooled to contract it. The differential pressure is small, so the power density is low, meaning that the engine will be large for a small power output.

The benefits of these engines are that they run very quietly, and that the parameters allow them to use solar heat and air-cooling, plus, they can be made with a low skill level and simple tools.

The Rider engine was quite successful just before the proliferation of electric motors. The coal-fired steam engines that were popular at the time required an expensive certified engineer to run them (due to high pressures), and Stirling engines did not.

Over 30,000 Riders were sold in various sizes, mainly to hotels and railroads. The hotels used them to pump well-water to a rooftop cistern, and it also heated the water in the process. The railroads used them to pump well-water to the elevated water storage tanks, to resupply locomotive steam-water in areas where there were inconsistent winds, which would have negated the use of the preferred windmill for pumping.

The rider uses two vertical/parallel cylinders using the Alpha configuration for air-flow. The hot piston compresses approximately 90-degrees of crank rotation before the cold piston. One cylinder is housed by a water jacket for cooling, the other uses a coal-fired jacket for heating. The crankshaft is at the top of the engine, so the pistons compress downward.

Each cylinder is a closely-fitted annular cylinder-within-a cylinder. As the piston compresses down the central cylinder, the working gas makes a U-turn at the bottom of the cylinder and then flows upward to the top of the cylinder. This is where the gas gains or sheds heat from the outer cylinder walls. When the gas reaches the top of the cylinder, it passes through the regenerator from the hot side to the cold side, back-and forth.

The regenerator is a type of “heat sponge” which increases the efficiency of the engine. The average temperature of the regenerator mass is about halfway between the hot side and cold side. Slow heat transfer from the engine to the internal air-mass is a limiting factor for the engines power output, and the regenerator mass increases the surface area of heat-transfer during the short time the working gas has to perform heat-transfer whether the air is heating or cooling.

An efficient regenerator reduces the engine-size and fuel-consumption for a given output. The Riders regenerator is a group of steel plates set closely together near the top of the two cylinders. The working gas must pass through the regenerator to pass between the hot and cold cylinders.

Both of the pistons are the displacement type, meaning the seals are stationary and located at the top of the two cylinders, and the pistons do not actually touch the cylinder walls. The seals are leather and have a trapezoidal shape to their cross-section, with the long side laying against the piston walls. An external drip of oil keeps the tops of the seals moist.

Using the displacement style of piston has several benefits. The cylinders and pistons can be manufactured from simple pipe sections, with the outer-cylinder ID keeping its stock finish, and then the OD of the piston-pipe being the part that requires honing and polishing. For a builder to improve the finish of a pipes OD, it is much easier than smoothing the ID.

The Rider has an air-pump and relief valve, which are used to maintain a 2-atmospheres of air-mass inside the engine. If additional air-mass is pumped into the engine above one atmosphere, it will increase the power density of the engine. Using more than 2-atmospheres is desirable, but at those pressures, organic oils and greases will ignite. The pump stroke is adjustable to make up for air leakage past the seals, which deteriorate over time (increasing leakage).

A typical rider installation operated a water-pump. The cold well-water was first pumped through the cold-cylinder housing to perform the cooling function, on its way to an elevated water-storage. The later engines used a longer piston than the earlier versions, and this placed the seals father away from the highest heat, which aided seal longevity.

The hot-cylinder seal experienced rapid degradation due to heat, and the later versions of the Rider had an additional small water-jacket around the hot seal. Cold well-water would be pumped through the large main water-jacket around the cold cylinder first, then the warmed water would then flow through the hot seal jacket, and then on to the elevated water-storage.

When contemplating the drawings in the patents, bear in mind there are two separate air-pump types presented as options. The first (Fig-4) is a simple displacement rod-piston pump (which does not require a polished cylinder bore) with stationary seals attached to the pump-cylinder, and using two check-valves.

The second air-pump (Fig-6) is a smooth-bore pump with a sliding seal incorporated into the piston. This pump style uses 3 check-valves and also an air-pressure accumulator. The Fig-6 pump is the better-performing type and is the preferred option, though it is more expensive.

The air-pumps can be adjusted to add air at the point of lowest internal pressure, or, at the point of greatest pressure. The benefit of adding air during the high-pressure power stroke is to allow the engine to run smoother. If adding air at the lowest internal pressure, the benefit is that less auxiliary power is drawn away from the crank, but it will cause the engine to pulse slightly.

The patent text image is somewhat awkward to read, therefore the archive has scanned the images by computer, rather than type them in. As a result, the archives plain-text version contains mis-spellings and various errors. Such as, the letter “C” is sometimes rendered as an “O” and a “6” is sometimes rendered as a “G”.

Also, in the manner of contracts written during this era, the sentences may be unusually long causing a difficulty in maintaining a readers train of thought. I have split various sentences in two, and occasionally updated punctuations to make the original words easier for the modern eye to read. Editors notes shall occasionally be found in [brackets], and no words were changed from the original.

This effort was embarked upon to better understand this engine in its most developed form, so as to enable modern builders to determine where improvements could be made, such as the implementation of Teflon seals and materials such as Stainless-Steel, aluminum, silicone-based lubricants, synthetic high-temperature grease, and various other modern options.

Rider Hot-Air Engine Patents

The well-developed 1886 model
http://www.google.com/patents?id=HI1TAAAAEBAJ

The early 1875 simple engine, patent #167,568
http://www.google.co.uk/patents?id=fp4CAAAAEBAJ

Selected paragraphs from his 1879 “improved engine” patent # 220,309
http://www.google.co.uk/patents?=Qj1bAA ... dq=220,309

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
No. 345,450
A. K. Rider AIR ENGINE, Patented July 13, 1886
UNITED STATES PATENT OFFICE
Alexander Kirk Rider, of Walden, New York. Air Engine.

Specification forming part of letters Patent No 345,450 dated July 13, 1886
Application filed January 30, 1880. Serial No 190,287 (No Model [submitted])

To all whom it may concern, Be it known that I, Alexander Rider, of Walden, in the county of Orange and State of New York, have invented a new and useful improvement in Air-Engines, of which the following is a specification

(line 7) My invention relates, generally, to air-engines of the class which operate in “closed cycle”- that is, using the same air over continuously, except the small portion escaping by leak, and the invention particularly relates to engines of their construction shown and described in my United States Patents No. 167, 568 dated September 7, 1875, and No. 220,309 dated October 7, 1879.

(line 16) The object of my invention is to increase the power of an air-engine of this class of a given size without materially increasing the cost of construction or lessening its simplicity. The invention consists in the combination, with an air-engine acting in closed cycle, and having uncovered cylinders and pistons, and an external heating device for heating the air within the engine, of an air-supply pump for maintaining the desired initial pressure of air inside the engine.

(line 27) The invention also consists in the combination, of an air-engine with an air-supply pump having its clearance-space variable by adjustment, to properly regulate the initial pressure in the engine.

(line 32) The invention also consists in an air-engine provided with an air-supply pump, and in which the increment of pressure caused by increasing the initial pressure is wholly or partially balanced by the weight of the pistons.

(line 37) The invention also consists in the combination, of an air-engine provided with the usual “suck-in” valve to prevent the minimum pressure in the engine from falling materially below the atmosphere, of an air-supply pump, whereby a sufficient pressure of air will be produced to open the suck-in valve before a partial vacuum is formed in the engine.

(line 46) The term “initial pressure” is used to imply the minimum pressure of air, or that which exists within the engine at its lowest pressure. In adapting my air-engine to use a high initial pressure of air I have found that the Power developed is in direct ratio to the weight of air present in the engine, or exactly in proportion to the initial pressure in atmospheres.

(line 55) But an initial pressure of two or more atmospheres cannot (in this construction of engine) be used without enclosing the pistons and covering the cylinders, nor could the initial pressure be regulated heretofore so as to come to a given limit constantly.

(line 60) In my improved practice, I do not carry the initial pressure beyond one and one-half atmospheres, which gives one and one-half times the power as compared with the same engine using an initial pressure of one atmosphere only.

(line 66) In carrying out my invention I employ a single-acting air-supply pump of small capacity attached to the engine for the purpose of re-supplying any leak of air, and to keep up the initial pressure to the desired degree.

(line 70) This air-supply pump is (in its most approved form) so constructed and combined with the engine so that its amount of clearance is variable and adjustable, and so that it is easy to adjust the relation between the compression and the clearance.

(line 76) [This will] cause the air supply pump to throw into the engine at each revolution, exactly the proper amount of air, and at the proper pressure to make up any loss of air by leak. [It will] at the same time keep the initial pressure or quantity of air contained in the engine constantly uniform.

(line 82) The regulation of the amount of clearance in the pump prevents any excess of pressure, while the comparatively large capacity of clearance insures the required quantity of air being delivered.

(line 86) I also employ means for balancing the increment of pressure consequent on the increased initial pressure. This is effected by weighting the pistons, which, as they reciprocate vertically, enables this to be readily done by making a greater or less portion of each piston solid.

(line 92) The pistons may in other ways be given the required weight to balance as near as possible the increment of pressure by gravitation, which effectually prevents the excess of friction which would otherwise occur in the crank pins and journals.

(line 99) In the accompanying drawings, Figure-1 is a vertical longitudinal section of an engine similar to those shown in my aforesaid patents, and which embodies my invention. Fig-2 is

Page 2
an end elevation of the engine from the cold (or compression) end, showing the air-supply pump in position thereon.

(line 3) Fig-3 is an elevation (on a larger scale) of a portion of the compression (or cold) cylinder, and also showing a vertical section of the air-supply pump with the means for adjusting its clearance. Fig.-4 is an elevation of the cold cylinder and its supply pump on the same scale as Fig.-3


(line 10) Fig-5 is a plan and horizontal section of a portion of the cold (or compression) cylinder. Figs. -6 and -7 are respectively an elevation and plan of the cold cylinder and supply-pump, Illustrating a modification of my invention which is designed to cause the injection of the supply of air from the pump to occur at the opposite part of the revolution of the engine from that which occurs with the arrangement of parts shown in Figs-4 and –5.

(line 20) Fig.-8 represents an indicator diagram of the engine, showing the action of the suck-in valve, and also the points of delivery of the supply-pumps. Fig.-9 is an elevation showing the suck-in valve and the air-supply pump, which is reversed in its action as compared with the pump shown in the former figures. Similar letters of reference designate corresponding parts in all the figures.

(line 29) The engine, as shown in Figs-1 and -2 is designed for pumping water, and may briefly described as consisting, essentially, of a hot cylinder and piston, and a cold cylinder and piston, with the ususal adjucts of connecting-rods, cranks, flywheel, etc.

(line 34) The air is heated and expanded in the hot cylinder, and after it has given out its force it is returned to the cold cylinder, where it is cooled and compressed, and then returned to the hot cylinder again, to be heated and expanded, and so on indefinitely.

(line 40) The water-jacketed part of the cold cylinder is termed the “cooler”. –A designates the water-pump (which may be of any suitable construction) and –B is the cold piston, which reciprocates within the cold cylinder –D. Then –E designates the cooler, which surrounds the cold cylinder, and –F designates the hot piston, which reciprocates within the hot cylinder –G.

(line 48) The pistons B/F transmit their motion through connecting-rods B1/F1 to a crankshaft (B2) upon which there is a flywheel (B3). Below the hot cylinder –G, is a heater –G1, into which the hot piston –F projects its downward movement, and within which the air is heated by a fire upon the grate –G2.

(line 55) The cold cylinder –D and the hot cylinder –G are connected by the air-passage –H, within which is placed the regenerator -H1, which is heated by the hot air on its return to the cold cylinder, and gives up such (saved) heat to the air as it returns to the hot cylinder after cooling and compressing.

(line 62) No further description of the principal parts of the engine is necessary.

(line 64) The water-pump –A may be bolted to the side of cooler –E, and its piston rod –a is connected with (and operated by) an arm (-a1) projecting from the cold piston –B, as shown in Fig.-3, and by an arm (-a2), as shown in Fig-9

(line 69) The air-supply pump here shown consists, essentially, of a barrel (or cylinder) –C, which may consist of a piece of brass tubing, and is secured to the cold cylinder at the points -c and -c1. Within this cylinder or barrel is a piston –C1, which, as here represented, is fitted with cup-leather packings, as best shown in Fig-3, and which is operated by a piston-rod –C2. As here represented, this rod –C2 is connected with (and operated by) the same arm, -a1, which operates the rod –a of the water-pump –A.

(line 79) The air-supply pump barrel/cylinder –C is open at its upper end, and at its lower end is fitted into a rectangular block (or chest) –c, which has inlet and outlet (check) valves d/d1 at its opposite sides, as best shown in Figs -4, -5, -6, and -7. The inlet valve –d is open to the atmosphere, and outlet valve –d1, is in a short curved tube, -d2, which enters the cold cylinder –D, as best shown in Figs -4, -5, -6, and -7, so as to deliver the air from the pump -C into the interior of the cold cylinder –D

(line 91) In order to provide for adjusting the clearance of the air-supply pump, I have represented its piston-rod (–C2) as secured on the arm –a1 of the cold piston by means of Jam-nuts (–c2) fitted to the rod above and below said arm. This piston-rod –C2 is of such length, that when the piston –C1 is adjusted to its lowest position it will come to the bottom of the pump-barrel –C at the end of its downward stroke.

(line 99) This rod is screw-threaded for a considerable part of its length, so that the piston can be adjusted into different positions upward or downward. The pump cylinder/barrel –C is also made a great deal longer than the actual stroke of the pump, so as to permit a wide range of position in the length of the cylinder or barrel for the actual stroke of the pump.

(line 107) By this arrangement the down-stroke of the pump may be completed when the piston –C1 reaches the bottom of cylinder –C. Or, it may be completed at about one-half way down the cylinder. Or, in any intermediate position between these two extremes.

(line 113) These changes depend upon the position given to the piston by altering the acting length of the piston-rod –C2 by means of its long threaded portion and the jam-nuts –c2 above and below the arm –a1.

(line 117) This construction permits the “clearance” or space below the piston –C1 at the end of its downward stroke to be varied and adjusted within wide limits. As the ratio between the length of stroke and length (or capacity) of clearance is an exact measure of the maximum pressure obtained, the air-supply pump can thus be made to deliver the air at a uniformly accurate degree of pressure continuously without being affected by ordinary variations in the quantity of air required.

(line 129) In the arrangement of parts just described, the air-supply pump delivery occurs at the end of the downstroke, which is also near the point of greatest compression in the



Page 3
cold cylinder of the engine.

(line 1) It may, however, be desirable in some cases to introduce the supply of air at the opposite extreme, or, at the point of minimum pressure in the cold cylinder. This can be readily effected by reversing the action of the supply-pump. Either by giving it reverse motion, or by causing the upstroke of the supply-pump to be the delivery-stroke, as shown in Fig -9.

(line 10) In Fig-9, the plunger C* works through a packing in the lower end of the pump-barrel –C, and the lower portion of the plunger is screw-threaded , as shown at –c1, and adjustably secured by jam-nuts –c2 in an arm –c4, with which is also connected a rod –c5, attached to the arm –a1 upon the hot piston –B.

(line 16) In this construction the air-inlet (or suction) valve –d of the pump is at the upper closed end of the cylinder –C, and the air discharge (or outlet) valve –d1 is near the lower end of the cylinder. This is similar to (or is) the usual suck-in valve of an engine.

(line 22) The construction, however, preferably used, where air is to be supplied to the cold cylinder near the point of minimum pressure is that shown in Figs -6 and -7 (which is essentially the same as the construction shown in Figs -4 and –5), with the addition of an extra check-valve (–d3), on the delivery side of the air-supply pump, and the air reservoir –I, mounted upon the air-supply pipe –d2 between the two check-valves –d1/-d3.

(line 32) The effect and operation of the arrangement shown in Figs -6 and -7 is, that the reservoir –I becoming a large addition to the clearance of the pump, the pressure within it is not sufficiently high to cause the air to enter the engine at the point of maximum pressure, though sufficient to do so at the point of lowest pressure, and the pressure in the reservoir is kept up to any required limit by the adjustment of the position of the supply-piston, as described.

(line 42) The adjustment of the capacity of clearance-space may also to some extent be effected by making the reservoir –I in two or more parts, so that its capacity may be changed by the use of any desired number of parts (or sections), or by increasing or diminishing its cubical contents in any other convenient manner, and in that case the regulation of the ratio of clearance can be thus effected.

(line 50) If a safety or blow-off valve were provided upon the reservoir -I, so as to maintain therein the desired pressure, the air-supply pump might be constructed without affording provision for adjusting its clearance.

(line 55) In engines of this type, as usually acting in open atmosphere, it is found necessary to have a suck-in valve. That is, a valve opening inward and attached to the cold cylinder or other convenient part of the engine. The purpose of this valve being to prevent (so far as is possible) the partial vacuum in the engine which would otherwise occur at the minimum pressure as a consequence of the leakage of air occurring at the point of highest pressure.

(line 65) This suck-in valve, being of small size, and from its construction being comparatively heavy, in order to fulfill its office [purpose], would take an appreciable [significant] pressure to lift it, and thus an initial pressure less than the atmosphere will exist in the engine, causing a loss of power. To obviate [remove] this defect is a further object and application of my invention when applied to an engine that does not have a sufficiently heavy piston for carrying much over one atmosphere.

(line 74) In this particular application of the invention, the main object sought is to insure a full atmosphere or a trifle [little] over one atmosphere in the engine at its lowest pressure, and for this purpose the supply-pump can be of the simpler type, as shown in Fig-9, and without means [needing a method] for adjusting its clearance.

(line 82) In Fig-9 the suck-in valve, as usually applied, is arranged at –d1, and constitutes the outlet or discharge valve of the pump, as before described. The operation of this construction is to cause the delivery of the supply air to occur at the time of lowest pressure in the engine, and to effectively prevent any partial vacuum in the interior of the cold cylinder.

(line 90) By the action of the pump shown in Fig-9 the air will be supplied under sufficient pressure to lift the suck-in valve and increase the amount of air in the cold cylinder at the point of minimum cold pressure, whereas the suck-in valve, if the pump were not used, would not be lifted until the pressure within the cylinder had fallen materially below the atmosphere.

(line 99) In Fig-1, P/P designate weights which are applied to the cold and hot pistons –B/-F, in order to (so far as is practicable) counterbalance the increment of upward pressure of the pistons due to carrying an initial pressure higher than one atmosphere.

(line 105) As shown in Fig-1, a portion of each piston is made solid; but this weighting might also be conveniently effected by thickening the side walls of the pistons to the required extent.

(line 109) I have herein described what I now consider the best and most effective means for carrying out my invention; but I would have it understood that I do not restrict myself solely to the exact construction herein set forth, but consider any modification of construction producing substantially the same results as fully within the scope of my invention.

What I claim as my invention, and desire to secure by Letters of Patent, is:

1. The combination, of an air-engine acting in a closed cycle, and having uncovered cylinders and pistons, and an external heating device for heating the air within the engine, and an air-supply pump for maintaining the desired initial pressure in the engine, substantially as herein described.

2. The combination, of an air-engine, with an air-supply pump having its clearance-space variable by adjustment, substantially as herein described.

3. An air-engine provided with an air-supply pump, and in which the increment of pressure caused by increasing the initial pressure is wholly or partially balanced by the weight of the pistons, substantially as herein described.

4. The combination, of an air engine provided with a suck-in valve to prevent the minimum pressure in the engine from falling materially below the atmosphere, and an air-supply pump, whereby a sufficient pressure of air will be produced to lift and open the suck-in valve before a partial vacuum is formed in the engine, substantially as herein described.

-Alexander Kirk Rider.

Witnesses:
W. G. Rutherford,
W. C. Stevens.

Rider early Hot-Air “simple” Engine 1875 Patent
http://www.google.co.uk/patents?id=fp4CAAAAEBAJ


A. K. RIDER. Air-Engine.
Patent No. 167,568.

Patented Sept. 7, 1875.
To all whom it may concern:
United States Patent Office,

ALEXANDER K. RIDER, of WALDEN, NEW YORK,
ASSIGNOR to RIDER, WOOSTER & CO., of the same place
.
IMPROVEMENT in AIR-ENGINES.
Specification forming Letters of Patent No. 167,568
dated September 7, 1875 ;
application filed August 2, 1875.

Be it known that I, Alexander K. Rider, of Walden, in the county of Orange and State of New York, have invented certain new and useful improvements in Air-Engines; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawing, which forms part of this specification.

This invention relates to engines which are designed to be operated by the successive compression, heating, expansion, and cooling of atmospheric air (or other gaseous fluid or vapor), applied either at its normal density, or at a higher or lower pressure, as desired. Such air, (or gaseous fluid or vapor) being used continuously, and merely passing from one portion of the engine to another part thereof alternately, and requiring no renewal besides that which may be necessary to re-supply deficiencies consequent [resulting due] to leakage.

The engine comprises a power or working cylinder, and a compression-cylinder, with their respective pistons, packings, connections, and main or fly-wheel shaft, together with a heater, regenerator, and cooler, and connecting openings or passages.

These devices, under different constructions, combinations, and arrangements, are used in other engines of the description my invention relates to.

The invention consists of certain novel constructions and combinations or arrangements of various parts of the engine, including a disposition of the compression-chamber and its cooler below the air-passage connecting said chamber with the heater of the power-cylinder.

Also, including a regenerator arranged within the connecting air-passage. Likewise, a regenerator of improved construction. A novel means of packing the cylinders or their pistons, whereby numerous specific advantages are obtained, and an air-engine combining increased durability with efficiency is produced.

Figure -1 represents an air-engine constructed in accordance with my invention. Fig-2 is an end view (upon a larger scale) of the regenerator.
-A is the power-cylinder situated directly [Page-1, Column 2] over the fire-chamber -B, and having attached to its lower flange -b the heater (-C), which may be similar to that described in Letters of Patent issued to me July 16, 1872, and reissued March 25, 1873.

Fitted to and inserted in the lower interior portion of the power-cylinder -A is a shield or tube (-D), the use of which is to deflect and distribute the inflowing air in a thin sheet over the interior surface of the heater -O, and thereby serve to produce a most efficient heating of the charge of air.

-E is the power- piston, the preferable construction of which, as here shown, is that known as the trunk [hollow]; but any other kind may be used. Said piston is extended downward into the heater, as usual, and its lower portion, is filled with nonconducting material to prevent the undue heating of the cylinder and packings.

It is shown connected direct[ly] to the crank -F on the engine shaft -S, but may be connected by beam or lever, if preferred. G/G1 are the piston-packings, which may be [made] of leather. These packings are in duplicate for each cylinder.

The lower one of these packings has its lap downward to resist the escape of the air below the piston, while the upper packing has its lap upward to prevent the lubricating material from entering too freely into the cylinder, and also to prevent the ingress of air when the interior treasure is less than that on the exterior of the piston, which will occur under certain conditions.

Between these two packings G/G1 is a relief-ring, -H. This ring is of peculiar construction, being much broader or thicker on its inner surface than its outer one, which latter unites with the former, by easy upper and lower curves, which give to it a flat outer disk-shape, and inner upright cylindrical form, and so that it meets the surface of the piston as a fillet on a flange meets its corresponding cylinder or groove. The inner edges of said ring are made as sharp and thin as practicable.

The object and use of this relief-ring are important. As leather packings are usually made they have a tendency to jam and produce great friction when the direction of motion under pressure is such as to condense the lap, the combined action of pressure and (Page 2) motion forcing the leather into a sharp corner, and against the cylinder is internal packing's, or against the piston in trunk-pistons, where the packing is external.

The relief-ring, constructed as described, entirely obviates this difficulty, by allowing the packing to slide onto the curvilinear surface, and effectually relieves the friction by the insinuation of the sharp edges of the ring between tlie piston and packing at the point of greatest resistance.

The packing has thus a vertically-changing motion in the direction of the piston's travel, the acting surface being reduced when the piston's motion is toward the packing, and increasing when the motion is reversed.

The relief-ring is, in this case, made double-acting—that is, it has a relieving edge on both sides. It may, however, be made single-acting when only one packing is used under pressure, and in that case only one side of the ring will require the relieving- edge. Said relief-ring and packings are held in position by the cap-ring-I, which is dished out on its upper side to give a convenient reservoir for the lubricant, and it is secured by bolts passing through it, through the cap- ring and an upper flange on the cylinder.

When such relief-ring is used with interior packings, as in the ordinary construction of piston, the same arrangement of parts will be made, excepting that the plano-cylindric form will be on the exterior edge of the relief-ring in place of the interior, as described.

-J is the compression-cylinder, having about the same piston development or area as the power-cylinder. It is also fitted with a trunk- piston (-K) and has packings G/G1, and with an interposed relief-ring -H, as herein before described, with reference to the power-cylinder -A and its piston -E.

Said cylinder -J rests on (and is secured by) its lower flange -c to the cooler -L, and is connected to the power-cylinder by the passage -M. The cooler -L is situated immediately under the compression-cylinder -J, and on its position and proper construction greatly depends the efficiency of the engine.

It is made double, to permit a constant current of cold water to surround the compression-chamber -J1, and keep it cool. The compression- chamber -J1 extends downward from the lower portion of the compression-cylinder -J to the base of the engine.

The piston -K of the compression-cylinder is made to fit it loosely, and to extend to the bottom of the compression-chamber at the lowest part of the stroke.

This position of the compression-chamber –J1 namely, wholly below the air-passage –M causes the oil used in lubricating to flow downward and collect in the bottom of the compression-chamber, from whence it can be readily blown out. This prevents the clogging up of the passage -M or other parts, which would otherwise occur.

The compression-piston -K nearly fills up the interior of the compression-chamber, and thereby causes the air on its return from the

[Page 2, Column 2]
heater to be presented in a very thin sheet to the cold surface of the compression-chamber -J1, and gives the highest efficiency in cooling the air previous to its compression.

-R is the regenerator. It is situated in the passage -M, between the power and compression cylinders, and is traversed each way by the air passing from one cylinder to the other. It is constructed of thin plates -d, made (preferably) of cast-iron.

The edges -c of these plates are thickened so as to give a uniform space between each plate of about one thirty-second of an inch, more or less. Said plates are disposed lengthwise of the passage, and give an uninterrupted airway with the least resistance through and between them.

The [regenerator] plates are set on edge to afford the greatest possible facility for their removal through a bonneted [removable top-cover] opening, in case they require cleaning.

–F1 is the crank on the shaft -S, to which the compression-piston -K is attached. The cranks F/F1 are arranged from eighty-five to ninety-eight degrees apart—that is, the one in advance of the other.

Their exact position is dependent on the amount of clearance or waste spaces around the pistons and in the passage-ways. The cranks being farthest apart when the clearance is at a minimum, the direction of revolution is such that the power- crank is in advance of the compression-crank.

When the engine is designed for pumping, the pump is bolted to the cooler and discharges into it, and the pump may be worked by an arm extending from an ear on the compression-piston, the cooler forming simply a part of the water-pipe.

The operation of the engine is briefly as follows: The compression-piston K first compresses the cold air in the compression-chamber -J1 into about one-third its normal volume (more or less) when, by the advancing or upward motion of the power-piston -B and the completion of the down-stroke of the compression-piston -K, the air is transferred from the compression-chamber -J1 through the regenerator -R, and into the heater -C, without appreciable change of volume.

The result is a great increase of pressure corresponding to the increase of temperature, and this impels the power-piston -E up to the end of its stroke. The pressure still remaining in the power- cylinder, and reacting on the compression- piston -K, forces the latter upward till it reaches nearly to the top of its stroke.

Then, by the cooling of the charge of air, the pressure falls to its minimum, the power-piston descends, and the compression again begins.

In the mean time the heated air, in passing through the regenerator, has left the greater portion of its heat in the regenerator-plates, to be picked up and utilized on the return of the air toward the heater, as in other hot-air engines.

I claim—

1. The compression-chamber -J1, with its cooler -L , arranged below the air-passage –M, [Page 3] which connects said chamber with the heater -C of the engine, whereby the lubricating material is restrained from clogging the passage -M and other parts connected therewith, and is collected in the bottom of said chamber, substantially as specified.

2. In combination with the power and compression cylinders -A and -J, and heater -C, the regenerator -R, composed of plates -d, arranged horizontally in the passage -M, between said cylinders, and communicating therewith at its ends (substantially as described) whereby the air passing from one cylinder to the other traverses said regenerator, and the air is heated and cooled, as and for the purpose described.

3. The relief-rings H, having their inner and outer surfaces of different breadths, united by one or more curves, and leaving it sharp edge at their junction with the piston or wearing surface, in combination with the packings G/G1, substantially as specified.

4. The combination of the power-cylinder -A, the piston –E, the shield or tube -D, the heater -C, the passage -M, and regenerator -M, the compression-chamber –J1, and its cooler -L, and the compression-cylinder -J, and its piston -K, the whole being arranged essentially as herein set forth.

A. K. RIDER.

Witnesses:

P. A. Decker,
James Gowdy.

Selected paragraphs from the intermediate “improved engine” Patent 220,309 from 1879

http://www.google.co.uk/patents?=QjlbAA ... dq=220,309

[Page 1, Column 2, para 2]
…My invention further consists in an air-engine provided with a sectional fire-chamber, to allow the ready removal and replacement of the heater when it has become impaired and unfit for further use…

…My invention further consists of an air-engine having an asbestos packing-ring interposed between the heater-flange and power-cylinder, to insure a tight and elastic joint between such parts…[It is worthy of note that the location of the asbestos gasket would also reduce the heat flowing from the hot-bottom of the power-cylinder to the top portion, where the leather seal is located]

…My invention further consists in an air-engine provided with a heater constructed of hard white iron, which is very refractory, and will withstand a high degree of heat for a much longer period than the ordinary soft-iron heaters…

…My invention further consists in an air-engine having either or both the power and compression pistons provided with a knuckle-joint for the attachment of the lower end of the connecting-rod, said joint constructed with an enlarged base and adapted to be adjusted circumfrentially…

[This would allow manual rotation and re-set of the cold piston in relation to the hot regenerator flow. This meant that the new-style pistons (with rotate-able wrist joint) could be retrofitted to the older engines. The newest 1886 engines no longer had a problem with lube-oil carbonizing on the side of the piston and oxidation-erosion of the polished piston-sides (which would prematurely wear-out the leather seals), but the older shorter 1875/1879 engines with that problem would still be in use]

[Page 3, Column 2, paragraph 1]
“…The [previous model] regenerator-chamber [was] in direct communication with an annular air-passage surrounding the compression-piston, the current of air being conveyed through the restricted annular passage formed between the piston and the inner surface of the cooler…

This construction is objectionable and defective for several reasons. The annular passageway varies in length, according to the position of the compression piston. When the piston is on its upstroke the cooling passage is shortened to an extent as to render the operation of cooling only partially effective.

In my improved construction the air entering the compression cylinder from the regenerator is caused to flow downwardly a certain fixed distance in direct contact with the cooling surface, and then beneath the compression-cylinder, and into the compression chamber –S, located below the compression-piston. [He added the second cylinder within each of the two main cylinders in the newest 1886 models to force the working air to travel down first, make a U-turn, and then flow upwards through a narrow annular passage before passing from one side of the engine over to the other, through the regenerator , located at the top]

…Another defect…the hot air flowing into the compression cylinder from the regenerator comes in direct contact with the surface of the compression-piston, and as it flows in quite a strong current, it operates to rapidly evaporate the lubricant on the piston…[adding the second annular cylinder also eliminated the hot-spot of air-blast exiting the regenerator, which hit a focused area on the piston]

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Editors notes:

After studying the Stirling engines and the Alpha configuration in particular, I have come to several conclusions.

The Rider-Ericsson version described herein has two vertical pistons, and since the preriferal leather seals are stationary and located at the top of the outer cylinders, the ID of the cylinders does not need to be machined. rather, they can be of a fairly smooth surface finish, and the stock surface finish found in common industrial pipe is adquate.

The OD of the pistons need to be smoothed and polished to a high level of finish, but this can be accomplished on the OD of the pipe stock used by employing methods and tools that are simple and readily available.

The Alpha configuration has two pistons that create an expanding interior volume on retraction, with the "cold" piston trailing behind at a 90-degree phase difference.

By comparison, a Gamma has only one piston on which the rise in pressure actuates against. The Gamma piston experiences more PSI against its working area, but...its power stroke is short. Therefore...it could be said that when comparing a Gamma to an Alpha, that the Alpha experiences the same amount of working force, but that it's power is spread over a much wider range of the crankshaft rotation. This can lead to using a smaller flywheel, and also provide a smoother running engine. Of course the cost is that the Alpha has two dynamic piston seals, where the Gamma has only one to be concerned with.

The Alpha pistons act as the power applyer, and also the displacers of the system. The RE style has the significant weight of these two heavy "pipe-like" pistons, lifted by the power stroke. This may initially be viewed as the weight of the pistons stealing some of the power stroke, but...it also means that when the pistons are falling on the downstroke, the energy that they "took" to be lifted is now returned to the cycle. In this way we can see that having heavy pistons would lead to a smoother running engine, but only if the are parallel, vertical, and the crankshaft is on the top of the engine.

If the engine were configured with the crank on the bottom, the power stroke and the weight of the pistons falling would coincide during the same half of a rotation, leading to very high vibrations.

The air-pump that exhausts to the interior is initially known to simply make up the air that would leak past the leather seals. Such leakage would slowly decrease power from the engine. It should be noted that the air-pump will also charge the interior of the engine with more air-mass than one atmosphere. The stroke of the pump is adjustable to make up for the expected seal wearing, but...it is also adjusted to increase the power of the engine, by allowing the engine to run with the interior charged to 1.5-2.0 atmospheres.

The amount of internal pressurization and the weight of the pistons should be carefully balanced. The stock pistons are designed to allow lead weights to be attached to their exposed tops (at the crank end) in order to facilitate this.

The regenrator is often described as making the engine more efficient, but...I would go on to say that a regenerator is vital to performance. Without the added heat-transferrence of the regenerator, the two cylinders would struggle to transfer an adequate amount of heat and cold to the working gasses. Without the regenerator, I would estimate that the engine would need to be three times larger to produce the same output, per a given design. Given the complexity of building any style of Stirling engine (however simple), the addition of the regenerator is a comparatively small extra effort for a clearly significant additional result.

The RE engine used a row of steel plates as fins + mass, which were simply placed in the passageway betwen the upper portion of the two pistons. Experimentation will need to be taken in order to determine the proper volume of regenerator plate vs the lost gas volume. The width of gap between the plates and the thickness of each plate is also a question of importance. I suspect that aluminum would be a much better plate material. Until WWII, aluminum was quite expensive and difficult to acquire.

pic from the web
http://hotairengines.org/images/d/e/8/2 ... -fig-2.png

Recently, I came to the realization that large and heavy vertical pistons are not a compromise or concession, it is a feature. Pressure lifts both pistons at 90-degrees of separation to each other, but...when the pressure decreases, the falling pistons add two more power pulses to the flywheel at 90-degrees of separation. The result is four evenly-spaced power pulses per rotation.

Of course, if the pistons were made to be as light as possible, then more of the expanding gasses would be taken up by the work-load, instead of lifting the heavy version of the pistons. However, when light pistons were falling, they would not add much to the flywheel. This means that light pistons would cause the engine to pulse more once per rotation.

Having heavy pistons does not "steal" power from the gasses lifting the pistons to perform work...the heavy pistons "borrow" some of the power on the lifting, and then immediately return the power to the flywheel when the pistons are falling.

The two pistons can have lead weight easily added or removed to balance them with the power strokes, and provide a smoother-running engine.