US2616244A

US2616244A - Device for varying the quantity of working medium in hot-gas reciprocating engines

Info

Publication number: US2616244A
Application number: US100380A
Authority: US
Inventors: Veldhuyzen Eduard Joha Jacobus
Original assignee: Hartford National Bank and Trust Co
Current assignee: Hartford National Bank and Trust Co
Priority date: 1948-07-02
Filing date: 1949-06-21
Publication date: 1952-11-04
Anticipated expiration: 1969-11-04

Description

Nov. 4, 1952 E. J. J. VELDHUYZEN 2,616,244

DEVICE FOR VARYING THE QUANTITY OF WORKING MEDIUM IN HOT-GAS RECIPROCATING ENGINES Filed June 21, 1949 501/020 J mv Jamal/5 Mflm/ YZEN.

J- a gn z Patented Nov. 4, 1952 DEVICE FOR VARYING THE QUANTITY OF WORKING MEDIUM IN HOT-GAS RECIP- ROCATING ENGINES Eduard Johan Jacobus Veldhuyzen, Amsterdam, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as

trustee Application June 21, 1949, Serial No. 100,380

In the Netherlands July 2, 1948 2 Claims.

This invention relates to hot-gas reciprocating I engines (which expression is to be understood to include refrigerating machines operating according to the reversed hot-gas engine principle) comprising a device for varying the quantity of working medium taking part in the cycle.

It is known to vary the quantity of working medium in a hot-gas reciprocating engine in order to vary the power absorbed or delivered by the engine at the instant at which the medium partaking in the thermo-dynamic cycle substantially attains the lowest pressure during a revolution. This method of control exhibits the disadvantage of being unsuitable for rapid control of this engine, which is disadvantageous, .for example with traction engines and engines driving generators.

If the power is required to be increased by supplying working medium, the medium added has a retarding effect on the working piston in this control method. At first, the work done in compressing the medium in one cycle exceeds the work done in compressing the medium in the preceding cycle and thus is greater in relation to the energy made available on expansion of the medium in the preceding cycle. Due to this, the power delivered by the machine is at first lower instead of higher and the engine tends to slow down. A similar phenomenon occurs, if the power is required to be reduced by decreasing the quantity of working medium. In this case, the work done in compressing the medium in one cycle is, at first, less than the work done in compressing the medium in the preceding cycle and thus is less in relation to the energy made available on expansion of the medium in the preceding cycle, so that at first the engine delivers a higher power instead of a lower power and tends to accelerate.

In effecting such control at the instant of substantially the lowest pressure occurring during the cycle, the range of variation of the power is comparatively small, since it is determined by the maximum permissible minimum pressure and the lowest attainable minimum pressure, for example, 1 atm. In this event, a variation of, say, 1 to 12 is possible, if the highest permissible minimum pressure is 12 atm. Moreover, it is difilcult to stop the engine at the lowest attainable minimumpressure, since, for example, the power delivered is still comparatively high with respect to frictional losses. Another disadvantage is that the means for control at the lowest pressure cannot serve simultaneously for driving the engine, owing to the supply of compressed air in this position of the piston and displacer, no positive work is performed by which the piston and displacer would be actuated. Consequently, an additional starting device is required.

The object of the invention is to provide an alternative construction of hot-gas reciprocating engine in which these difficulties are avoided.

According to the invention, a hot-gas reciprocating engine having a device for varying the quantity of working medium taking part in the cycle, is characterized in that it comprises means by which the working space of the engine, both at the instant of supplying working medium and at the instant of carrying off working medium, can be made to communicate periodically with a second chamber containing Working medium,

in that position of the piston and displacer in which the medium taking part in the thermodynamic cycle has attained substantially the highest pressure occurring during the cycle.

This control method is very suitable for traction engines and for engines driving generators. If the quantity of medium is increased at substantially the highest pressure occurring during the cycle, the highest pressure of the medium increases, so that the medium added immediately partakes in the expansion phase of the cycle.

The energy made available on expansion of the medium in a cycle initially exceeds the energy made available on expansion in the preceding cycle and thus is greater in relation to the work done in compressing the medium in the preceding cycle, due to which the engine immediately delivers a higher power. Upon reducing the quantity of medium, the highest pressure of the medium taking part in the cycle decreases, with the result that a quantity of medium is carried off and does not partake in the subsequent expansion, so that the energy made available on expansion of the medium in a cycle is initially less than the energy made available on expansion in the preceding cycle and thus is smaller in relation to the work done in compressing the medium in the preceding cycle.

In this method of control it is possible to vary the power to a much higher degree, since the range of variation is determined by the highest permissible maximum pressure and the lowest attainable maximum pressure occurring during a cycle, for example 1 atm. Owing to this, a variation of, say, 1 to 30 is possible, if the highest maximum pressure is 30 atm. Moreover, the engine can be stopped if the maximum pressure becomes equal to atmospheric pressure, since, for example, the power then delivered is comparatively low with respect to frictional losses. In addition, starting the engine with the use of compressed air in the correct positions of the piston and the displacer. if required after turning, will be possible by the same means which serve for controlling the power output, since in these positions of the piston and the displacer positive work is delivered, by which the piston and the displacer are actuated. In this event, the provision of a separate starting device is not necessary.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying diagrammatic drawing which represents, by Way of example, a hot-gas reciprocat ing engine according thereto.

Fig. 1 is a view partly in crosssection of a hot-gas engine employing applicants invention;

piston 1 and a displacer 2,-which determine the" space in which the cycle takes place, which space comprises a cold chamber 3 and a hot chamber 4. The cold chamber 3 is connected with the hot chamber 4 by way of a cooler 5, a regenerator t and a heater 7. Both the piston l and the displacer 2 are connected, by connecting rods, to a crank-shaft 8. The crank associated with the piston I and the crank associated with the displacer 2 may be arranged at an angle of 90 to one another.

A channel H contains a control valve 9 which is kept closed by means of a spring I0. Through the channel H, the cold chamber 3 may be made to communicate with a control chamber I2 in which a desired pressure can be maintained.

When it is desired to start the engine, either the control chamber IE or a separate starting vessel l3 may be used, which vessel may be connected with the working space of the engine through channel H by way of a cock I4, a cock l5 controlling the connection between the working space and the chamber 12 then being closed.

The valve 9 can be opened by means of a lever l6, a lifting rod I1 and a cam l8. Fig. la is a 4 side view of this cam. The shape of the cam I8 is such that the valve 9 opens when the pressure of the working medium taking part in the cycle substantially attains its highest value;

It is clear that, besides in the manner illustrated in the drawing, the invention may be carried out in many other ways, for instance by means of slides and cooks, without departing from its scope.

What I claim is:

l. A hot-gas reciprocating engine comprising a working space, a crankshaft, a piston connected thereto reciprocating in said working space, a chamber containing Working medium at a variable predetermined pressure, conduit means connecting said chamber to said working space and valve means interposed in said conduit means and actuated by said crankshaft to open said valve means at the point of highest pressure in the cycle in order to supply or carry ofi' working medium to or from said Working space.

2. A hot-gas reciprocating engine comprising a working space. a crankshaft, a piston connected thereto reciprocating in said working space, a chamber containing Working medium at predetermined pressure, conduit means connecting said chamber to said working space to supply or carry off working fluid to 'or from said working space, valve means interposed in said conduit means to control the flow therethrough, resilient means to normally close said valve means, cam means driven by said crankshaft to open said valve means at the point of highest pressure in the cycle.

EDUARD JOHAN JACOBUS VELDHUYZEN.

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

UNITED STATES PATENTS Number Name Date 826,313 Clark July 17, 1906 FOREIGN PATENTS Number Country Date 2,999 Great Britain Dec. 7, 1860 1,784 Great Britain Apr. 14, 1882