ALPHA STIRLING ENGINE

Abstract

An alpha type Stirling engine (1) comprises an expansion cylinder (2) and a compression cylinder (3). The Stirling engine further comprises a regenerator (4), a cooler (5), a heater (6), and a gas channel (7) which provides the expansion cylinder (2) in fluid communication with the compression cylinder (3). At least one of the expansion cylinder (2) and the compression cylinder (3) has a twin cylinder (2, 3) which functions as an additional expansion cylinder (2) or an additional compression cylinder (3), respectively, wherein the one of the expansion cylinder (2) and the compression cylinder (3) that has a twin cylinder (2, 3), is together with said twin cylinder (2 3) connected to a first portion (7a) of the gas channel (7), from which first portion (7a) the gas channel (7) extends via the regenerator (4) to a second portion (7b) to which the other one of the expansion cylinder (2) and the compression cylinder (3) is connected.

Claims

1. An alpha type Stirling engine comprising: an expansion cylinder; a compression cylinder; a regenerator, a cooler, a heater, and a gas channel which provides the expansion cylinder in fluid communication with the compression cylinder; wherein at least one of the expansion cylinder and the compression cylinder has a twin cylinder which functions as an additional expansion cylinder or an additional compression cylinder, respectively, and wherein the one of the expansion cylinder and the compression cylinder that has a twin cylinder, is together with the twin cylinder connected to a first portion of the gas channel, from which the first portion of the gas channel extends via the regenerator to a second portion to which the other one of the expansion cylinder and the compression cylinder is connected.

2. The Stirling engine according to claim 1, wherein both the expansion cylinder and the compression cylinder have a twin cylinder, respectively, wherein the expansion cylinder and the twin cylinder of the expansion cylinder are connected to the first portion of the gas channel, while the compression cylinder and the twin cylinder of the compression cylinder are connected to the second portion of the gas channel.

3. The Stirling engine according to claim 1, wherein the twin cylinder is arranged parallel to at least one of the expansion cylinder and the compression cylinder.

4. The Stirling engine according to claim 1, wherein the one of the expansion cylinder and the compression cylinder that has a twin cylinder comprises a piston configured to move along a first geometrical axis, wherein the twin cylinder comprises a piston configured to move along a separate second geometrical axis, wherein the first and the second geometrical axes are parallel with each other.

5. The Stirling engine according to claim 1, wherein the twin cylinder is arranged in line with at least one of the expansion cylinder and the compression cylinder, with the cylinder heads facing each other.

6. The Stirling engine according to claim 1, wherein the expansion and compression cylinders are configured in a V-arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments of the present invention, wherein:

[0022] FIG. 1 is a schematic drawing of a Stirling engine according to the present disclosure,

[0023] FIG. 2 is a schematic drawing of an alternative setup of twin cylinders according to the present disclosure, and

[0024] FIG. 3 is a schematic drawing of a V-type Stirling engine according to another exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0025] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Like reference character refer to like elements throughout the description.

[0026] With reference to FIG. 1, the alpha type Stirling engine 1 comprises an expansion cylinder 2 and a compression cylinder 3. It further comprises a regenerator 4, a cooler 5, and a heater 6. The expansion cylinder 2 Furthermore, the Stirling engine comprises a gas channel 7 which provides the expansion cylinder (2) in fluid communication with the compression cylinder (3). As shown in FIG. 1, both the expansion cylinder 2 and the compression cylinder 3 have a twin cylinder 2, 3, respectively. However, in other exemplary embodiments, it is conceivable that only one of the expansion cylinder 2 and the compression cylinder 3 has a twin cylinder. This will at least reduce the strain on one of the cylinders compared to if a single cylinder solution is used on on both the compression side and the expansion side of the regenerator 4.

[0027] From a fluid path perspective, the expansion cylinder 2, its twin cylinder 2 and the heater 6 are provided on one side of the regenerator 4. The compression cylinder 3, its twin cylinder 3 and the cooler 5 are provided on the other side of the regenerator 4.

[0028] The twin cylinders 2, 3 function as additional expansion and compression cylinders 2, 3, respectively. The expansion cylinder 2 and its twin cylinder 2 are both connected to a first portion 7a of the gas channel 7. The compression cylinder 3 and its twin cylinder 3 are both connected to a second portion 7b of the gas channel 7. Each one of the cylinders 2, 2, 3, 3 has a reciprocating piston 8, 8, 9, 9, respectively. The gases pushed by the pistons 8, 8 of the pair of expansion cylinders 2, 2 are joined in the first portion 7a of the gas channel 7 and transported via the regenerator to the second portion 7a of the gas channel 7 and the distributed to the compression cylinders 3, 3, whereby the pistons 9, 9 of the compression cylinders will perform a retracting motion of its stroke. Correspondingly, when the pistons 9, 9 are advanced to push the gas, the flow will be in the opposite direction.

[0029] By having a common gas channel 7 with which the pair of compression cylinders 3, 3 the pair of expansion cylinders 2, 2 interact, the forces needed to drive the pistons 8, 8, 9, 9 to achieve the desired gas flow in the gas channel 7 can be reduced for the individual pistons without compromising on power output.

[0030] As further can be seen in FIG. 1, the twin cylinders 2, 3, the expansion and compression cylinders 2, 3 are arranged parallel with one another in pairs, respectively. In particular, the pair of expansion cylinders 2, 2 are arranged along separate but parallel geometrical axes, along which the respective piston 8, 8 moves. Similarly, the pair of compression cylinders 3, 3 are arranged along separate but parallel geometrical axes, along which the respective piston 9, 9 moves.

[0031] Moving on to FIG. 2, the twin cylinders 2, 3 are arranged in line with the expansion cylinder 2 and/or the compression cylinder 3, respectively, with the cylinder heads 10 facing each other. One advantage is that the cylinders or rather the pistons will balance each other throughout the strokes.

[0032] In FIG. 3, it is schematically shown how the cylinders 2, 2, 3, 3 are arranged or configured in a V-arrangement. The two pairs of cylinders are turned 90 degrees for facilitating understanding. From one side where the V-shape is visible, only one cylinder will be visible for each leg of the V. Also in this configuration the movements of the pistons in the expansion cylinder 2 and its twin cylinder 2 are along parallel geometrical axes. Similarly, the movements of the pistons of the compression cylinder 3 and its twin cylinder 3 are along parallel geometrical axes.

[0033] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. For example, the arrangement shown in FIG. 2, with the cylinder heads 10 facing each other, could be applied to the V-arrangement of FIG. 3.