Abstract
The invention relates to an internal combustion engine comprising a combustion cylinder housing a combustion piston, a compressor cylinder housing a compressor piston, an expander cylinder housing an expander piston, and a crankshaft connected to the combustion piston and the expander piston by a respective connecting rod. The internal combustion engine further comprises a connecting element rigidly connecting the compressor piston and the expander piston such that the compressor piston and the expander piston move in unison.
Claims
1. An internal combustion engine comprising: at least one combustion cylinder housing a combustion piston, said combustion cylinder being configured to be energized by forces of combustion; a compressor cylinder housing a compressor piston, said compressor cylinder being configured to compress a volume of air and transfer the compressed air to the at least one combustion piston; an expander cylinder housing an expander piston, said expander cylinder being configured to receive exhaust gases from the at least one combustion piston; a crankshaft connected to said at least one combustion piston and said expander piston by a respective connecting rod, characterized in that the internal combustion engine further comprises a connecting element rigidly connecting said compressor piston and said expander piston such that the compressor piston and the expander piston move in unison.
2. An internal combustion engine according to claim 1, wherein said compressor piston is connected to said crankshaft via said expander piston, such that a rotational motion of said crankshaft is transferred into a reciprocating motion of said compressor piston via the expander piston connecting rod.
3. An internal combustion engine according to claim 1, wherein said crankshaft is driven by said at least one combustion piston by means of the combustion piston connecting rod, and is driven by said expander piston by means of said expander piston connecting rod, wherein said compressor piston is driven by said crankshaft by means of said expander piston.
4. An internal combustion engine according to claim 1, wherein said expander piston has an expander piston height and an expander piston diameter, and wherein the expander piston height is smaller than ⅓ of the expander piston diameter.
5. An internal combustion engine according to claim 1, wherein said compressor piston has a compressor piston height and a compressor piston diameter, and wherein the compressor piston height is smaller than ⅓ of the compressor piston diameter.
6. An internal combustion engine according to claim 1, wherein at least a portion of said compressor piston, at least a portion of said expander piston and at least a portion of said connecting element together forms a compressor-expander arrangement surrounding a portion of said crankshaft.
7. An internal combustion engine according to claim 1, wherein said expander piston has a circular cross section extending in a first geometrical plane, and said compressor piston has a circular cross section extending in a second geometrical plane, said first and second geometrical planes being positioned in a parallel configuration on opposite sides of a longitudinal axis of the crankshaft.
8. An internal combustion engine according to claim 1, wherein said expander cylinder and said compressor cylinder are co-axially arranged.
9. An internal combustion engine according to claim 1, wherein a reciprocating motion of said expander piston inside of said expander cylinder occurs along an expander axis, and a reciprocating motion of said at least one combustion piston inside said combustion cylinder occurs along a combustion axis, and wherein said expander cylinder and said at least one combustion cylinder is arranged inside said internal combustion engine in such way that said expander axis is angled in relation to said combustion axis by between 40 degrees and 90 degrees.
10. An internal combustion engine according to claim 1, further comprising an expander piston sealing arrangement sealing said expander piston to an inner surface of said expander cylinder, and a compressor piston sealing arrangement sealing said compressor piston to an inner surface of said compressor cylinder, wherein said expander piston sealing arrangement is independent from said compressor piston sealing arrangement.
11. An internal combustion engine according to claim 10, wherein said expander piston sealing arrangement comprises a liner, comprised in an inner surface of said expander cylinder, and at least one metal ring arranged circumferentially in an outer surface of said expander piston, and wherein said compressor piston sealing arrangement comprises a polished surface comprised in an inner surface of said compressor cylinder, and at least one non-metallic and/or polymeric ring arranged circumferentially in outer surface of said compressor piston.
12. An internal combustion engine according to claim 1, wherein said at least one combustion cylinder is a first combustion cylinder and said combustion piston is a first combustion piston, and said internal combustion engine further comprises a second combustion cylinder housing a second combustion piston, said second combustion cylinder being configured to be energized by forces of combustion.
13. An internal combustion engine according to claim 12, wherein said first and second combustion cylinders operate in a four-stroke configuration, and each one of said compressor and expander cylinders operate in a two-stroke configuration.
14. An internal combustion engine according to claim 12, wherein said compressor cylinder is a first compressor cylinder and said compressor piston is a first compressor piston, said expander cylinder is a first expander cylinder and said expander piston is a first expander piston, and said connecting element is a first connecting element, said internal combustion engine further comprises: a third combustion cylinder and a fourth combustion cylinder housing a respective third and fourth combustion piston, said combustion cylinders being configured to be energized by forces of combustion; a second compressor cylinder housing a second compressor piston, said second compressor cylinder being configured to compress a volume of air and transfer the compressed air to the third and fourth combustion pistons; a second expander piston cylinder housing a second expander piston, said second expander cylinder being configured to receive exhaust gases from the third and fourth combustion pistons; a second connecting element rigidly connecting said second compressor piston and said second expander piston such that the second compressor piston and the second expander piston move in unison, wherein said crankshaft is connected to said third and fourth combustion pistons and said second expander piston by a respective connecting rod.
15. A vehicle comprising an internal combustion engine according to claim 1.
16. An internal combustion engine according to claim 1, wherein said expander piston has an expander piston height and an expander piston diameter, and wherein the expander piston height is smaller than smaller than 1/15 of the expander piston diameter.
17. An internal combustion engine according to claim 1, wherein said compressor piston has a compressor piston height and a compressor piston diameter, and wherein the compressor piston height is smaller than 1/10 of the compressor piston diameter.
18. An internal combustion engine according to claim 1, wherein a reciprocating motion of said expander piston inside of said expander cylinder occurs along an expander axis, and a reciprocating motion of said at least one combustion piston inside said combustion cylinder occurs along a combustion axis, and wherein said expander cylinder and said at least one combustion cylinder is arranged inside said internal combustion engine in such way that said expander axis is angled in relation to said combustion axis by between 55 degrees and 65 degrees.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) 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:
(2) FIG. 1 is a side view of a vehicle comprising an internal combustion engine according to an example embodiment of the present invention;
(3) FIGS. 2A and 2B are perspective views of the internal combustion engine according to an example embodiment of the present invention;
(4) FIG. 3 is a perspective view of the internal combustion engine according to yet another example embodiment of the present invention;
(5) FIG. 4 schematically illustrates an internal combustion engine according to an example embodiment of the present invention;
(6) FIG. 5 schematically illustrates parts of the internal combustion engine of FIG. 4.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION
(7) The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which an exemplary embodiment of the invention is shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein; rather, the embodiment is provided for thoroughness and completeness. Like reference character refer to like elements throughout the description.
(8) With particular reference to FIG. 1, there is provided a vehicle 1 with an internal combustion engine 200 according to the present invention. The vehicle 1 depicted in FIG. 1 is a truck for which the inventive internal combustion engine 200, which will be described in detail below, is particularly suitable for.
(9) Turning to FIGS. 2A and 2B, which illustrate an internal combustion engine 200 according to an example embodiment of the present invention. A full illustration of the cylinders housing the respective pistons have been omitted from FIGS. 2A and 2B for simplicity of understanding the invention and the piston configuration.
(10) The internal combustion engine 200 comprises a first combustion cylinder 210 housing a first combustion piston 212, and a second combustion cylinder 214 housing a second combustion piston 216. The internal combustion engine 200 further comprises a compressor cylinder 220 housing a compressor piston 222, and an expander cylinder 230 housing an expander piston 232. It should be understood that the first and second combustion pistons 212, 216 are individually arranged inside the first and second combustion cylinders 210, 212, respectively, and are adapted for reciprocating motion therein. Correspondingly, the compressor piston 222 and the expander piston 232 are arranged inside the compressor cylinder 220 and the expander cylinder 230, respectively, and are adapted for reciprocating motion therein.
(11) As shown in FIG. 2A, the internal combustion engine 200 comprises a crank shaft 240, and an expander piston connecting rod 234 connecting the expander piston 232 to the crankshaft 240. Correspondingly, a first combustion piston connecting rod 213 connects the first combustion piston 212 to the crankshaft 240, and a second combustion piston connecting rod 217 connects the second combustion piston 214 to the crankshaft 240. Thus, the above mentioned reciprocating motions of the pistons can be transferred into a rotational motion of the crankshaft 240.
(12) In FIG. 2A, the expander piston 232 is connected to the compressor piston 222 by a connecting element 250. More specifically, in FIG. 2A, the expander piston 232 is connected to the compressor piston 222 by three connecting arms 252, 254, 256 arranged in a respective periphery portion of the expander and compressor cylinders 232, 222. Each one of the connecting arms 252, 254, 256 extends from the expander piston 232 to the compressor piston. Even though three connecting arms 252, 254, 256 are shown in FIG. 2A, it should be understood that other number of connecting arms, or only one connecting arm, may be used within the concept of the invention. Thus, at least one embodiment, the connecting element 250 comprises at least one connecting arm 252, 254, 256, such as e.g. three connecting arms 252, 254, 256. Moreover, the connecting element 250 may be arranged with no connecting arms, but instead as e.g. a connecting envelope extending from the expander piston 232 to the compressor piston 222, such that the expander piston 232 and the compressor piston 222 move in unison. Hence, in the following description the connecting element 250 will be referred to in singulars.
(13) The connecting element 250 is to be understood as rigidly connecting the expander piston 232 to the compressor piston 222, such that the expander piston 232 and the compressor piston 222 move in unison. The expander piston 232 may comprise at least an expander volume facing surface 232A, and a crankshaft facing surface 2328, and correspondingly the compressor piston 222 may comprise at least a compressor volume facing surface 222A, and a crankshaft facing surface 222B. Thus, the connecting element 250 rigidly connects the expander piston 232 with the compressor piston 222 such that the respective crankshaft facing surfaces 232B, 222B faces each other. Hence, as the compressor piston 222 moves in a downstroke (i.e. in order to compress the air in the compressor cylinder 220), the expander piston 232 moves in a stroke following the motion of the compressor piston 222. Correspondingly, as the expander piston 232 moves in an upstroke, the compressor piston 222 moves in a stroke following the motion of the expander piston 232.
(14) As shown in FIG. 2A, the compressor cylinder 220 and the expander cylinder 230 are positioned on opposite sides of, and in close proximity to, the crankshaft 240. Stated differently, a portion 242 of said crankshaft 240 is arranged in between the expander piston 232 and the compressor piston 222, such that the portion 242 is arranged between the respective crankshaft facing surfaces 232B, 222B. In other words, the compressor piston 222, the expander piston 232 and the portion 242 of the crankshaft 240 are arranged along a geometrical axis GA, and the portion 242 of the crankshaft 240 is along the geometrical axis GA in between the compressor piston 222 and the expander piston 232. The internal position of the components in the internal combustion engine 200 may be described in a different manner:
(15) at least a portion of the compressor piston 222, such as its crankshaft facing surface 222B, at least a portion of the expander piston 232, such as its crankshaft facing surface 232B, and at least a portion of the connecting element 250 together forms a compressor-expander arrangement 260 enclosing the portion 242 of the crankshaft 240.
(16) In at least a third way of describing the internal position of the components in the internal combustion engine 200, the expander piston 232 has a circular, or round, cross section extending in a first geometrical plane, and the compressor piston 222 has a circular, or round, cross section extending in a second geometrical plane, the first and second geometrical planes being positioned in a parallel configuration on opposite sides of a longitudinal axis LA of the crankshaft 240.
(17) As seen best in FIG. 2B, the expander piston 232 is configured for a reciprocating motion inside of the expander cylinder 230 along an expander axis EA. Correspondingly, the compressor piston 222 is configured for a reciprocating motion inside of the compressor cylinder 220 along a compressor axis CA. Correspondingly, the first combustion pistons 212 is configured for a reciprocating motion inside of the first combustion cylinder 210 along a combustion axis CoA1, and the second combustion pistons 216 is configured for a reciprocating motion inside of the second combustion cylinder 214 along a combustion axis CoA2. As seen in FIG. 2B, the expander cylinder 230 and the compressor cylinder 220 are co-axially arranged, i.e. the expander axis EA and the compressor axis CA are aligned.
(18) Turning back to FIG. 2A, it is shown that first combustion cylinder 210, and the second combustion cylinder 214 may be described as protruding laterally from said crankshaft 240 compared to the expander cylinder 230. Thus, the expander cylinder 230, and the first and second combustion cylinders 210, 214 are arranged inside the internal combustion engine 200 in such way that the expander axis EA is angled in relation to each one of the combustion axis CoA1, CoA2 by between 40 degrees and 90 degrees, preferably between 50 degrees and 75 degrees, and more preferably between 55 degrees and 65 degrees, such as e.g. about 60 degrees.
(19) Moreover, the expander piston 230 has an expander piston height H2 and an expander piston diameter D2, wherein the expander piston height H2 is smaller than ⅓ of the expander piston diameter D2, preferably smaller than ⅕ of the expander piston diameter D2, or more preferably smaller than 1/10 or 1/15 of the expander piston diameter D2. In FIG. 2A, shown as an example, the expander piston height H2 is about 1/10 of the expander piston diameter D2.
(20) Correspondingly, the compressor piston 220 has a compressor piston height H1 and a compressor piston diameter D1, wherein the compressor piston height H1 is smaller than ⅓ of the compressor piston diameter D1, preferably smaller than ⅕ of the compressor piston diameter D1, or more preferably smaller than 1/10 or 1/15 of the compressor piston diameter D1. In FIG. 2A, shown as an example, the compressor piston height H1 is about 1/12 of the compressor piston diameter D1. As also shown in FIG. 2A, the compressor piston diameter D1 is smaller compared to the expander piston diameter D2.
(21) The function of the internal combustion engine 200 will now be further elucidated with reference FIG. 2B. The compressor cylinder 220 is configured to draw a volume of ambient air, compress the air, and transfer the compressed air to the first and second combustion cylinders 210, 214. The first and second combustion cylinders 210, 214 are configured to be energized by forces of combustion, e.g. by ignition of the fuel by means of a spark plug (e.g. as for a petrol or gasoline driven engine) or heat originating from compression (e.g. as for a diesel driven engine). The expander cylinder 230 is configured to receive exhaust gases from the first and second combustion pistons 210, 214. Transportation of air, fuel and gases are carried out by means of inlet valves, transfer ports, and outlet valves known by the skilled person in the art, and which fluidly interconnects the compressor cylinder 220, the first and second combustion cylinders 210, 214 and the expander cylinder 230.
(22) Note that in the internal combustion engine 200 in FIG. 2A, the compressor piston 222 is not directly connected to the crankshaft 240, via its own connecting rod, but is instead connected to the crankshaft 240 via the connecting element 250, the expander piston 232 and the expander piston connecting rod 234. Hereby, the rotational motion of the crankshaft 240 (indicated by rotational arrows) is transferred into a reciprocating motion of the compressor piston 220 via the expander piston connecting rod 234. Thus, the crankshaft 240 is driven by the first and second combustion pistons 212, 216 by means of the respective combustion piston connecting rods 213, 217 and is driven by the expander piston 232 by means of the expander piston connecting rod 234, but the crankshaft 240 drives the compressor piston 222 by means of the expander piston 230 and the expander piston connecting rod 234.
(23) FIG. 3 shows an internal combustion engine 400 comprising a first engine half 401 and a second engine half 402. The first and second engine halves 401, 402 are each one identical and comprise the same components as the internal combustion engine shown in FIGS. 2A and 2B. As the components and their respective functions have been described with reference to FIGS. 2A and 2B, they are not repeated in detail here again. However, the main components of the internal combustion engine 400 are briefly described.
(24) The internal combustion engine 400 in FIG. 3 comprises a first combustion cylinder 410 housing a first combustion piston 411, a second combustion cylinder 412 housing a second combustion piston 413, a third combustion cylinder 414 housing a third combustion piston 415, and a fourth combustion cylinder 416 housing a fourth combustion piston 417. The internal combustion engine 400 further comprises a first compressor cylinder 420 housing a first compressor piston 422, a second compressor cylinder 424 housing a second compressor piston 426, a first expander cylinder 430 housing a first expander piston 432, and a second expander cylinder 434 housing a second expander piston 436. It should be understood that the pistons are individually arranged inside the respective cylinders, and are adapted for reciprocating motion therein. Moreover, the internal combustion engine 400 of FIG. 4 comprises a first connecting element 450 rigidly connecting the first compressor piston 422 and the first expander piston 432 such that the first compressor piston 422 and the first expander piston 432 move in unison, and comprises a second connecting element 452 rigidly connecting the second compressor piston 426 and the second expander piston 436 such that the second compressor piston 426 and the second expander piston 436 move in unison. Moreover, a crankshaft 440 is connected to the first, second, third and fourth combustion pistons 411, 413, 415, 417 by a respective connecting rod, and is connected to the first and second expander pistons 432, 436 by a respective connecting rod.
(25) FIG. 4 schematically illustrates an internal combustion engine 500 according to an example embodiment of the present invention. The internal combustion engine 500 comprises a combustion cylinder 510 housing a combustion piston 512, a compressor cylinder 520 housing a compressor piston 522, and an expander cylinder 530 housing an expander piston 532. It should be understood that the combustion piston 512 is arranged inside the combustion cylinder 510 and is adapted for a reciprocating motion therein. Correspondingly, the compressor piston 522 and the expander piston 532 are arranged inside the compressor cylinder 520 and the expander cylinder 530, respectively, and are adapted for reciprocating motion therein.
(26) As shown in FIG. 4, the internal combustion engine 500 comprises a crank shaft 540, and an expander piston connecting rod 534 connecting the expander piston 532 to the crankshaft 540. Correspondingly, a combustion piston connecting rod 513 connects the combustion piston 512 to the crankshaft 540. Thus, the above mentioned reciprocating motions of the pistons can be transferred into a rotational motion of the crankshaft 540.
(27) In FIG. 4, the expander piston 532 is connected to the compressor piston 522 by a connecting element 550. More specifically, in FIG. 4, the expander piston 532 is connected to the compressor piston 522 by two connecting arms 552, 554. Each one of the connecting arms 552, 554 extends from the expander piston 532 to the compressor piston 522. The connecting element 550 is to be understood as rigidly connecting the expander piston 532 to the compressor piston 522, such that the expander piston 532 and the compressor piston 522 move in unison. Hence, as the compressor piston 522 moves in a downstroke (i.e. in order to compress the air in the compressor cylinder 520), the expander piston 532 moves in a stroke following the motion of the compressor piston 522. Correspondingly, as the expander piston 532 moves in an upstroke, the compressor piston 522 moves in a stroke following the motion of the expander piston 532.
(28) As shown in FIG. 4, the compressor cylinder 520 and the expander cylinder 530 are positioned on opposite sides of, and in close proximity to, the crankshaft 540. Stated differently, a portion 542 of said crankshaft 540 is arranged in between the expander piston 532 and the compressor piston 522.
(29) The internal combustion engine 500 in FIG. 4 may e.g. be used in a serial hybrid, e.g. as a range extender. In such embodiments, the crankshaft 540 may not be directly coupled to the driving means of the vehicle.
(30) In FIG. 4, the compressor piston 522, the expander piston 532, the crankshaft 540, the expander piston connecting rod 534, and the connecting element 550 may be referred to as a crankshaft assembly 501 in accordance with the third aspect of the present invention. Optionality, the combustion piston 512 and the combustion piston connecting rod 513 and/or any one of the cylinders 510, 520, 530 are comprised in the crankshaft assembly 501.
(31) FIG. 5 show parts of the internal combustion engine 500, or parts of the crankshaft assembly 501, of FIG. 4. In FIG. 5 an expander piston sealing arrangement 535 sealing the expander piston 532 to an inner surface of the expander cylinder 530, and a compressor piston sealing arrangement 525 sealing the compressor piston 522 to an inner surface of the compressor cylinder 520 is shown (the cylinders 530, 520 have largely been omitted from FIG. 5, and the distances between the inner surfaces of the cylinders 520, 530 and the respective pistons 532, 522 have been exaggerated, for simplicity of understanding the sealing arrangements 535, 525). As is clear from FIG. 5, the expander piston sealing arrangement 535 is independent, and functionally separated, from the compressor piston sealing arrangement 525. More specifically, in FIG. 5, the expander piston sealing arrangement 535 comprises a honed liner 536 comprised in an inner surface of said expander cylinder 530, and at least one metal ring 537 arranged circumferentially in an outer surface of the expander piston 532 (as shown in FIG. 5, more metal rings, such as e.g. three metal rings may be arranged circumferentially in the outer surface of the expander piston 532). Moreover, the compressor piston sealing arrangement 525 comprises a polished surface 526 comprised in an inner surface of said compressor cylinder 520, and at least one non-metallic, or polymeric, ring 527 arranged circumferentially in an outer surface of the compressor piston 525 (as shown in FIG. 5, more non-metallic, or polymeric, rings, such as e.g. two rings may be arranged circumferentially in the outer surface of the compressor piston 522).
(32) 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.
