Gearbox for realizing discontinuous piston movement in hot gas engines based on the Stirling principle

Abstract

A ratchet mechanism for use in hot gas engines based on the Stirling principle is presented to effect a discontinuous movement of the pistons. The solution proposed here uses a ratchet mechanism (ratchet = pause) to generate a discontinuous movement (translation) with standstill phases from a continuous movement (rotation) and thereby approximate the actual motion sequence in the machine to the ideal Stirling process. The aim of the invention is to improve the efficiency in the machine's working process. The transitions between the different phases are not abrupt here either; that is, small deceleration and acceleration phases still occur during the transitions, which must be considered desirable since transitions are unavoidable due to inertia. The direct conversion into linear motion can be considered particularly advantageous. Detent gears of this type are known and are described, for example, in the "Kinematics of Planar Planetary Gears" by U. Trempler, HTW Dresden. The novelty claimed here is the use of a detent gear in hot gas engines based on the Stirling principle. The gear (2) runs in the stationary internal gear ring (1), Fig. 3, driven by the eccentric (5) on the machine shaft (4). The lever (3), with its driver (6), is rigidly connected to the gear. The driver engages in the slot of the (here raised) crank loop (7) and linearly displaces the piston rod (8), which is guided in suitable bearings. Conversely, the piston rod drives the gear via the crank loop, the driver, and the lever, which in turn drives the machine shaft via the eccentric. The tooth ratio between the internal gear ring and the gear is 4:3.

Description

[0001] This document presents a ratchet mechanism for use in Stirling-type hot gas engines to achieve a discontinuous piston movement. In this context, a Stirling-type hot gas engine refers to any machine that operates using the Stirling process as a motor, heat pump, or refrigeration unit; here, it is also simply called a Stirling engine. The Vuilleumier heat pump is also included in this definition.

[0002] Until now, Stirling engines have been designed almost exclusively with either crank drives or as free-swinging engines for understandable practical reasons. In these designs, the pistons follow a sinusoidal oscillation more or less exactly. The phases in the Stirling process are strictly separated from one another ( Fig. ), are not achievable in this way. To approximate the sequence of the four phases of the Stirling process, a specific phase angle is structurally introduced between the displacer and working pistons. This leads to the well-known rounding of the curve in the pv diagram ( Fig. Since the area enclosed by the curves directly represents the power output, they clearly illustrate the remaining reserves of work performance and efficiency at that point. The aim of the invention is to utilize these resources in the best possible way.

[0003] There have been attempts to address this problem using cam gears, but these have obviously not yet led to a satisfactory solution.

[0004] The solution proposed here uses a ratchet mechanism (ratchet = pause) to generate a discontinuous movement (translation) with standstill phases from a continuous movement (rotation) and thereby approximate the actual motion sequence in the machine to the ideal Stirling process.

[0005] The transitions between the different phases are not abrupt here either; that is, small deceleration and acceleration phases still occur during the transitions, which must be considered desirable since transitions are unavoidable due to inertia. The direct conversion into linear motion can be considered particularly advantageous.

[0006] Detent gears of this type are known and are described, for example, in the "Kinematics of Planar Planetary Gears" by U. Trempler, HTW Dresden. Their use in Stirling engines is claimed here as a novelty.

[0007] The gearbox presented here is primarily suitable for Stirling engines in a gamma configuration. It can also be used for Stirling engines in a beta configuration. This gearbox is not applicable to Stirling engines in an axiom configuration, also known as rider motors.

[0008] Two different subtypes of this gearbox are possible. One subtype with a direct 1:3 gear ratio and the other with a 1:1 gear ratio. Gear ratio here refers to the number of revolutions of the machine shaft per Stirling cycle.

[0009] Normally, a separate gearbox is required for the working piston and the displacer piston. However, in the gamma Stirling engine, it is also possible to achieve the same motion sequence with only one gearbox by arranging the cylinders at a 90° angle. Fig. On the extended driver (6), the crank loops (7) and (7B) run one behind the other and in a direction of movement rotated by 90° relative to each other. This drives the two piston rods sequentially. This option is available for both subtypes of the gearbox.

[0010] To achieve the best possible simulation of the Stirling cycle, the eccentrics on the machine shaft have a phase angle of 90° to each other, and the direction of the angle determines the direction of rotation of the machine shaft. 1.1 Gearbox with 1:3 ratio

[0011] In the fixed inner gear ring (1), Fig. The gear (2), driven by the eccentric (5), runs on the machine shaft (4). The lever (3), with its driver (6), is rigidly connected to the gear. The driver engages in the slot of the (here raised) crank loop (7) and linearly displaces the piston rod (8), which is guided in suitable bearings. Conversely, the piston rod drives the gear via the crank loop, the driver, and the lever, which in turn drives the machine shaft via the eccentric. The tooth ratio between the internal gear ring and the gear is 4:3. 1.2 The movement sequence

[0012] Starting from position A in Fig. The machine shaft (4) rotates with the eccentric (5) from position B to position C. In doing so, the machine shaft is rotated twice by 135°. The gear, which is rotatably mounted on the eccentric, rolls in the internal gear ring (1), and its point of engagement moves synchronously with the eccentric from A* via B* to C*. The lever (3) with the driver (6) moves from A** via B** to C**, a distance of 90°. The complete and continuous path of the driver through a full cycle is shown by curve (9). Therefore, the machine shaft must complete 4 x 270° = 3 revolutions for one full cycle of the Stirling process. 1.3 Origin of the movement break

[0013] The movement of the driver is transmitted to the piston rod via the crank loop (7), ( Fig. During the movement of the driver (6) from A to B along the motion curve (9), the piston rod (8), guided in the linear guide (10), must follow the driver with the crank loop (7). On the path from B to C, however, it can remain largely stationary. On the path from C to D and from D back to A, the process is repeated in the opposite direction with respect to the piston rod. Since these paths are associated with the same angles of rotation on the machine shaft, the times for these phases are also the same. 2.1 Gearbox with 1:1 ratio

[0014] The gearbox with a 1:1 ratio is in Fig. analogous to Fig. The difference consists of a reduction of the teeth of the gear (2) to 1 / 4 of the number of the inner gear ring (1), the resulting change of the eccentric (5) and a shortening of the lever for the driver, which now lies within the radius of the gear and is not shown. 2.2 The movement sequence

[0015] Here too, in Fig. The rotation of the machine shaft (4) with the eccentric (5) from position A via B to C takes place again. During the quarter turn of the machine shaft, the driver (6) moves a quarter of the way along the path of motion (9). This results in a transmission ratio of 1:1.

Claims

[1] Detent gear for use in a hot gas engine based on the Stirling principle in β or γ configuration or in a Vuilleumier heat pump, for implementing the Stirling cycle as a motor, as a heat pump or as a refrigeration machine, here collectively referred to as a Stirling engine, with 2 detent positions and 2 movement phases per piston, evenly distributed over the cycle, for controlling the movement of the pistons, consisting of: 1.1 an internal gear ring fixed radially symmetrically around the machine shaft with an internally rotating solitary planet gear in a tooth ratio of either 4 : 3 or 4 : 1, 1.2 an eccentric located on the machine shaft, which drives the planetary gear via its axis, or is driven by the planetary gear, 1.3 an axially aligned driver at a suitable radial distance from the axis of rotation of the planet gear, which is firmly connected to the same, 1.4 a piston rod guided by a suitable linear guide, connected to a crank loop into which the driver engages. [2] Ratchet mechanism according to claim 1, characterized by , that for use in the Stirling engine both the displacer piston and the working piston each have their own gearbox. [3] Ratchet mechanism according to claim 1, characterized by , that for use in a γ-Stirling engine with cylinder arrangement in 90° position, a single gearbox with extended driver engaging in 2 crank loops rotated 90° against each other is sufficient. [4] Ratchet mechanism according to claims 1 and 3, characterized by that the option according to claim 3 applies to both subtypes of the transmissions. [5] Ratchet mechanism according to claim 1, 2, 3 and 4, characterized by, that in the Stirling engine the displacer piston and the working piston alternately take equal periods of pause between the individual phases of movement. [6] Ratchet mechanism according to claim 1, 2, 3, 4 and 5, characterized by , that in the Stirling engine the displacer piston and the working piston move alternately. [7] Ratchet mechanism according to claim 1, 2, 5 and 6, characterized by , that in the Stirling engine the eccentrics on the machine shaft for displacer pistons and working pistons are rotated 90° relative to each other. [8] Ratchet mechanism according to claim 1, 2, 3, 4, 5 and 6, characterized by , that in the Vuilleumier heat pump the two pistons are treated analogously to the working piston and displacer piston in the Stirling engine. [9] Ratchet mechanism according to claim 1, 2, 3, 4, 5, 6 and 7, characterized by, that if required, an additional gearbox, symmetrical to the plane of the crank loop and coupled by a connecting, common driver, enables axial continuation of the machine shaft with force input / output.

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