US3811272A

US3811272A - Stirling cycle engine power control means

Info

Publication number: US3811272A
Application number: US00305074A
Authority: US
Inventors: S Hakansson
Original assignee: United Stirling AB and Co
Current assignee: United Stirling AB and Co
Priority date: 1971-11-09
Filing date: 1972-11-09
Publication date: 1974-05-21
Anticipated expiration: 1991-05-21
Also published as: GB1317352A

Abstract

To control the power of a hot gas Stirling cycle engine a dead volume chamber is connected with the low temperature working chamber by two valves. The first valve has a smaller opening thereby operating the engine to absorb power acting as a brake. The second valve has a larger opening which permits the engine to idle at reduced power.

Description

Unlted States Patent [1 1 [111 3,811,272 Hakansson May 21, 1974 [54] STIRLING CYCLE ENGINE POWER 2,602,288 7/1952 Rinia et al. 60/24 CONTROL A S 2,607,190 8/1952 2,61 L237 9/1952 [75] Inventor: Sven Anders Samuel Hakansson, 2317.950 12 1957 Malmo, Sweden 3,600,886 8/1971 .laspers et al. 60/24 [73] Assignee: Kommanditbolaget United Stirling (Sweden) AB Malmo, v Primary Examiner-Edgar W. Geoghegan Sweden Assistant Examiner-H. Burks, Sr. I 221 Filed; 9, 1972 Attorney, Agent, or FirmLaurence R. Brown, Esq. [21] App]. No.: 305,074

[30] Foreign Application Priority Data [57] ABSTRAT NOV. 9, 197' Great Britain I. 5l865/7l To control the power of a hot ga y le ngi e a dead volume chamber is connected with the low [52] US. Cl. 60/518 temperature ki Chamber by two valves The first Clvalve has a maller opening operating -the ene Fleld of Search gine to absorb power acting as a brake econd V valve has a larger opening which permits the engine to [56] References cued I idle at reduced power.

UNITED STATES PATENTS 987,938 3/1911 Anderson 60/24 ux 5 Claims, 3 Drawing Figures PATENTEDHAY 21 197 2 3,8 1.1, 272

SHEET 1 BF 2 Fig.1

PATENTEBma 1 m4 SHEET 2 0? 2 STIRLING CYCLE ENGINE POWER CONTROL MEANSv This invention relates to a hot gas engine of the kind (herein called.the kind defined") comprising a variable volume first working chamber connected through a regenerator to a variable volume second working chamber, the first working chamber containing working gas at a temperature higher than that of the gas in the second working chamber, and one of said chambers being connected to a control chamber'through controllable passage means, that is to say passage means which can be selectively fully open or fully closed or regulated to allow restricted flow of gas.

If connected to one of the working chambers the said control chamber will act as a dead volume and will cause a decrease in the engine power output. Therefore, it is convenient to govern the power output of a hot gas engine by connectinga working chamber selectively to one or more dead volume chambers of different sizes.

However, it has hitherto been considered necessary to use very large dead volume chambers if a decrease in engine power output down to idling is to be obtained solely by such means.

The present invention is therefore intended to provide a hot gas engine of the kind defined in which a dead volume power output control of moderate size may serve effectively as the only power output control means.

According to the invention there is provided a hot gas engine of the kind defined characterised in that the said controllable passage means comprises two or more parallel connections each of which is controllable.

The scope of the monopoly sought is defined in the claims hereinafter, and how the invention may be put into practice is described in more detail with reference to the accompanying drawings, in which FIG. 1 schematically shows a hot gas engine according to the invention,

FIG. 2 shows a diagram illustrating the variations in the power output of a hot gas engine in dependence upon the opening of passage means between an engine working chamber and a dead volume" chamber of constant volume, and

FIG. 3 shows a vertical section through parts of a secnd hot gas engine according to'the invention. 7

The hot gas engine shown schematically .in FIG. 1 is of the single-acting type comprising a cylinder 1 with two

pistons

2 and 3. The engine contains working gas in a high temperature working chamber 4 and in a lowtemperature working chamber 5. The two chambers 4 and 5 are interconnected through a passage containing a regenerator 6 and a cooler 7. A heater 8 maintains the temperature of the high temperature working chamber 4.

The low temperature working chamber 5 is connected to a control chamber 9 of constant volume. The chamber 9 is a dead volume chamber and is connected to the chamber 5 through passage means comprising two parallel connections 10' and l 1, each being controllable by a

valve

12 and 13 respectively.

The two

pistons

2 and 3 are provided with

piston rods

14 and 15 which in turn are connected to a drive. mechanism (not shown) so that the movements of the piston 2 are 90 degrees in advance of the movements of the piston 3.

The engine illustrated in FIG. 1-will operate as follows:

Assume that the engine is running at constant temperatures in the high and low temperature working chambers 4 and Sand at a constant mean pressure of the working gas. Initially the

valves

12 and 13 are closed to shut off completely the connections 10 and 11 to the dead volume control chamber 9. The engine is now running at an output power corresponding to the value A in the diagram of FIG. 2, in which the ordinates represent the engine power output values while the abscissae represent the extent of the opening of the connections l0 and 11.

From FIG. 2 it will be understood that openingof the connections 10 and 11 to a small extent will immediately cause a substantial decrease in the engine power output down to a value B, which in the case illustrated is negative, i.e., the engine absorbs power from a flywheel or other moving parts and theload and acts as a brake. A further opening of the passages 10 and 11 will cause an increase in power output to a value C which may be for example 40 percent of the value A. The two connections 10 and 11 may be designed so that full opening of the valve 12 only will cause the engine output to reach the value B, while full opening of the valve 13 only will. cause the engine output to reach the value C. I

FIG. 3 shows in vertical section a double-acting hot gas engine comprising a cylinder 20having a single piston 21 mounted'for reciprocating therein. The piston 21 is provided with a piston rod 22 secured to a crosshead 23 with a connection rod 24 journalled on a crank-shaft 25 in conventional manner.

The piston 21 separates a high temperature working chamber 26 from a low temperature working chamber 27. The high temperature working chamber 26 is connected to a system of pipes 28.arranged to be heated by heat developed in a combustion chamber 29.

Through a channel 30 the low. temperature working chamber 27 is connected to a cooler 31 and a regenerator 32, which in turn is connected to a pipe system 33 similar in type to the pipe system 28.

It will be understood that in a four-cylinder doubleacting hot gas engine the cranks of the crank-shaft 25 may be displaced relative to' each other, and the ar-' rangement may be such that an expansion of the high temperature working'chamber 26 may be effected 90 in advance of an expansionof the respective low temperature working chamber 27. Thus the working cycle of the engine of FIG. 3 is substantially the same as that of the engine shown in FIG. 1.

The channel 30 may communicate with a dead volume chamber 34 through openings governed by two

valve members

35 and 36 respectively. The said valve members are in the form of pistons arranged movably in

cylinders

37 and 38 respectively. The valve member 35 governs a smaller opening which when open whilst the other valve is closed will cause the engine to act as a brake. The piston 36 governs a larger opening which when open whilst the other valve is closed will cause a reduction inengine output whilst maintaining a moderately high degree of efficiency.

The

valve members

35 and 36 may be governed by working gas of either the highest or the lowest working gas cycle pressure fed to the interior of the

cylinders

37 and 38 through

pipes

39 and 40..

The dead volume control chamber 34 may be connected to a further dead volume control chamber 41 by an opening governed by a valve 42. The effect of thus adding the chamber 41 to the chamber 34 will be to decrease the engine output to a greater extent when the valve 36 is opened.

For simplicity in construction and operation it is preferred to provide only two parallel controllable connections between a working chamber and a dead volume chamber, the control means being such that each of the said connections can merely be selectivelyfully open or fully closed, but it will be appreciated that it is possible to provide one or more further controllable connections in parallel with the said two connections and that the connections may be provided with valves or other control means which allow regulation of the gas flow therein.

What we claim is:

1. Power control means for a hot gas engine having high temperature and low temperature working chambers, comprising in-combination, a dead volume control chamber, at least two passageways from said low temperature working chamber to said =dead volume control chamber tocontrol the size ofopening into said chamber from saidlow temperature workingchamber at a set of valves representing predetermined lower engine output'pow'er levels, at least one valve of which provides braking by the engine thereby absorbing energy from a load connected thereto, and independently operable valve means for selectively opening and closing each of said passageways separately thereby establishing said predetermined engine output power levels.

2. Power control means as defined in claim 1, wherein the size of said passageways is different to offer different resistance to gas flow therethrough.

3. Power control means as defined in claim 2,-

wherein the size of said passageways is selected so that when the smaller passageway only is opened the engine will absorb power and act as a brake, and when the 5. Power control means as defined in claim 1, includ" ing a second dead volume chamber, a passageway between the two dead volume chambers and selectively operable valve means opening and closing said latter passageway. 1 1 I

Claims

1. Power control means for a hot gas engine having high temperature and low temperature working chambers, comprising in combination, a dead volume control chamber, at least two passageways from said low temperature working chamber to said dead volume control chamber to control the size of opening into said chamber from said low temperature working chamber at a set of valves representing predetermined lower engine output power levels, at least one valve of which provides braking by the engine thereby absorbing energy from a load connected thereto, and independently operable valve means for selectively opening and closing each of said passageways separately thereby establishing said predetermined engine output power levels.

3. Power control means as defined in claim 2, wherein the size of said passageways is selected so that when the smaller passageway only is opened the engine will absorb power and act as a brake, and when the larger passageway is opened the engine will run at reduced power.

4. Power control means as defined in claim 1, wherein each valve means comprises a piston member, and means for controlling said piston members to open and close said passageways with gas pressure corresponding respectively to the lowest and highest working gas pressures of said engine.

5. Power control means as defined in claim 1, including a second dead volume chamber, a passageway between the two dead volume chambers and selectively operable valve means opening and closing said latter passageway.