US2596058A - Hot-gas engine with displacer cap safety venting means - Google Patents

Description

y 1952 F. VAN WEENEN 2,596,058

HOT-GAS ENGINE WITH DISPLACER CAP SAFETY VENTING MEANS Filed April 12, 1946 INVENTOR. Frunciscus Lumber'rus Von Weenen Patented 'May 6, 1952 HOT-GAS ENGINE WITH DISPLACER 'GAP SAFETY VENTING .MEAN S Franciscus Lambertus van Weenen, Eindhoven, Netherlands, assignor, by mesne assignments, to Hartford National BankandTrus't Company, Hartford, Conn, as trustee Application April 12, 1946, Serial No. 661,629

3 Claims.

With hot-gas engines it is known to provide the displacer which is adapted to move in the hot chamber of the engine with a cap of poor heat-conductive material. This cap has primarily the function of securing thermal insulation between the hot and the cold chambers of the engine, said chambers :being separated by the displacer.

In order that the good heat-insulating properties of a displacer provided with such a cap may be fully utilised it is desirable that the connection between this cap and the displacer should be gas-tight. This is also desirable in view of the fact that if this connection would have a slight leakage of air, useless work would be performed by the engines in order to pump the medium into and out of the cap. Truly in the presence of a very small leak in this connection this pumping would not yet lead to appreciable losses, but when the engine has .run for a considerable time at a very high pressure level the presence of such a small leak may cause the pressure in the cap to assume a high value. On the pressure level in the engine being then suddenly lowered, the cap may be pushed off the displacer by the much higher gaseous pressure prevailing in it, unless there is a very heavy and hence frequently inconvenient attachment between the cap and the displacer. To obviate this difiiculty, a solder joint between the cap and the displacer has generally been provided in hot gas engines.

The present invention provides the possibility of adopting a materially simpler but satisfactory method of attachment between the cap and the body to which this cap is secured.

The hot-gas piston engine (hot-gas engine, refrigerating machine working on the reversed hot gas engine principle), in which the pistonlike body that moves in the machine space in which or adjacent which caloric energy is absorbed by the medium active in the machine, has secured to it a cap of poor heat-conductive material. In the arrangement disclosed herein this cap is set tightly on the said body by a screw attachment and the space between the cap and the piston-like body is in permanent communication with a further space in which the pressure at a given moment is at the utmost no more than equally high as the pressure which at that moment prevails in the cycle of operations in the machine, it being structurally simple to cause the space between the cap and the piston-like body to be in communication with the crank chamber of the machine, because if this chamber, as is the standard practice, is shut off from the surthe Netherlands c'to'ber29, 1945 (C1. Bil-24) active in the machine or to roundings in which the machine is arranged a pressure prevails in it which is about equal to the mean pressure level in the machine or is lower than this pressure. If thus at a given moment the working medium should leak unexpectedly, through the connection between the cap and the displacer into the cap, it is possible for this medium to leak away in turn in an unhampered manner through the said connection to the crank chamber. This connection may be formed by a recessed portion in the displacer connecting rod or else by a pipe provided in the machine for this purpose.

Guided by the idea on which the present invention is based its sufiices to use a simple screw connection, such as a central screw bolt connection, for the attachment of the cap to the associated piston-like body.

In order that the invention may be clearly understood and readily carried into effect it will now be described more fully with reference to the accompanying drawing, in which a hot gas piston machine is diagrammatically shown.

Referring to the single figure of the drawing, l designates the housing of the machine, 2 the cylinder liner, 3 the crank chamber, t the displacer, 5 the cap which is secured to the displacer and is made of material having poor heat conducting properties, such as vanadium alloy steel, '6 the piston, l the piston connecting rod, 8 the crank, 9 the crank shaft, H] the displacer connecting rod, ll, l2, l3 and M the rods which couple the expeller connecting rod to the piston rod 1 and which serve to cause the displacer 4 to move with the desired phase-displacement relatively to the piston I. In addition, l5 and I6 designate the two devices which serve respectively to supply caloric energy to the medium withdraw this energy from this medium and I! the regenerator. From the chamber [8 arranged over the displacer 4, the medium active in the machine flows via the heat exchanger l5, the regenerator l'!, the heat exchanger l6 to the space l9 between the lower side of the displacer 4 and the upper side of the piston 6 and vice versa. If the hot gas piston machine is constructed to form a, hot gas engine, the medium active in the engine is caused to assume the required temperature by heat from without via the heat exchanger l5 and the medium is cooled via the exchanger It. In this case, a temperature prevails in the chamber I8, which is then referred to as the hot chamber, which is materially higher than the temperature in the chamber l9, which is then referred to as the cold chamber. If the hot gas piston machine is in tended to operate as a refrigerating machine, the heat exchanger I5 is arranged in the surroundings to be cooled and a lower temperature prevails in the chamber l8, then referred to as cooled chamber, than in the chamber l9 (hotter chamber) the caloric energy absorbed by the heat exchanger being conducted away by means of the heat exchanger 16 at a higher temperature.

Now, if, as stated herein-before, the cap 5 would be secured to the displacer 4 by a soldering joint and this joint would inadvertently have a small leakage of air, the space within the cap, if the medium active in the machine is at a very high pressure, is gradually filled with medium which also is at a very high pressure. If the pressure in the machine is then suddenly lowered to a very great extent,for example in connection with the control of the machine, the space within the cap is still at the originally high pressure and there is the risk that after the breakdown of the soldering joint the cap 5 is pushed ofi the displacer 4 by this high pressure with the result that the machine gets out of order. Now, in the form of construction of the machine according to the invention as shown on the drawing this is avoided by causing the space in the cap 5, by means of the pipe 20 which extends through the piston body 6, permanently to communicate with the space inside the crank chamber 3, which is shut off from the surroundings, so that the pressure prevailing within the cap never exceeds that in the crank case 3. takin particular measures to secure the cap 5 to the displacer 4 in a particularly solid matter, so that in the case shown it suflices to secure this cap to the displacer body 4 by means of a single central screw bolt 2|. It is only natural that by the provision of fitting edges or the like care will be taken that the connecting edge between the cap 5 and the displacer 4 is gas-tight, because there would otherwise be the probability of leakage of the working medium from the machine space via the pipe 20 to the crank case.

What I claim is:

1. In a hot gas engine, the combination of a displacer element, cap means attached to said displacer and forming an enclosed space therebetween, a closed crank case, crank means in said crank case, means operatively connecting said displacer with said crank means in said crank This avoids the need for s 4 7 case, and fluid conducting means directly connecting said enclosed space with said closed crank case whereby the pressures in said enclosed space and said enclosed crank case are maintained substantially equal.

2. In a hot gas engine, the combination of a casing, a displacer element located in the casing, 7

cap means attached to said displacer and enclosing a space therebetween, an enclosed crank case, piston means located in said casing between the displacer element and the enclosed crank case to define a chamber between said displacer element and said piston means, and tube means connecting said enclosed space and said enclosed crank case, said tube means passing through but not communicating with said chamber and also passing through said piston whereby the pressure in said enclosed space and said enclosed crank case are maintained substantially equal.

3. In a hot gas engine, the combination of a casing, a displacer element located in the casing and movable for reciprocatory motion therein, cap means attached to said displacer and enclosing a space therebetween, an enclosed crank case, crank means in said crank case, means operatively connecting said displacer with said crank means in said crank case, piston means located in said casing between the displacer element and the enclosed crank case to define a chamber between said displacer element and said piston ,means, means operatively connecting said piston means with said crank means, and fluid conducting means directly connecting said enclosed space and said enclosed crank case, said fluid conducting means passing through but not communicating with said chamber and also passing through said piston whereby the pressure in said enclosed space and said enclosed crank case are maintained substantially equal.

FRANCISCUS LAMBERTUS VAN l/VEENEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 374,123 Hopkins Nov. 29, 1887 942,261 Hubbard Dec. 7, 1909 1,073,065 Anderson et a1 Sept. 9, 1913 1,730,580 Lundgaard Oct. 8, 1929

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