Constant-volume combustion engine

Abstract

The invention relates to a constant-volume combustion engine (10; 110; 210), in particular a reciprocating engine for generating mechanical energy by the expansion of a gas or a hot gas from the combustion of a gas mixture or gas-fuel mixture, having at least one piston/cylinder unit, the piston (14; 114; 214) of which is connected to a piston rod (20; 120; 220), wherein said piston rod (20; 120; 220) is drivingly connected to at least two crankshafts (30, 40; 130, 140; 230a, 230b, 240), the first crankshaft (40; 140; 240) being mounted, such that it can rotate eccentrically, on the second crankshaft (30; 130; 230a, 230b), which is parallel thereto and is rotationally coupled thereto.

Claims

1. A constant-volume combustion engine, in particular a reciprocating piston engine for generating mechanical energy by way of expansion of a gas or a hot gas from the combustion of a gas mixture or gas/fuel mixture, having at least one piston/cylinder unit, the piston of which is connected to a piston rod, the piston rod being drive-connected to a first and a second crankshafts, wherein the first crankshaft is mounted eccentrically rotatably on the second crankshaft which is arranged parallel to it, and is rotationally coupled to said second crankshaft; wherein the first and the second crankshafts perform a sinusoidal rotational movement, and the piston rod, or at least an additional connecting part, is mounted rotatably with a first eccentricity (d.sub.1) on the first crankshaft, wherein the first crankshaft is mounted with a second eccentricity (d.sub.2) on the second crankshaft, the second eccentricity (d.sub.2) being between three and five times as great as the first eccentricity (d.sub.1), the crankshafts being arranged relative to one another in such a way that the amplitude of the sinusoidal curve of the rotational movement of the second crankshaft is between three and five times as great as the amplitude of the sinusoidal curve of the rotational movement of the first crankshaft.

2. The constant-volume combustion engine as claimed in claim 1, wherein the rotational coupling of the first crankshaft to the second crankshaft comprises at least two gearwheels.

3. The constant-volume combustion engine as claimed in claim 1, wherein the first and the second crankshafts move in opposite directions to one another.

4. The constant-volume combustion engine as claimed in claim 1, wherein the second crankshaft has at least one seating region for seating and rotatably mounting the first crankshaft.

5. The constant-volume combustion engine as claimed in claim 4, wherein the at least one additional connecting part can comprise a connecting rod and/or a lever.

6. The constant-volume combustion engine as claimed in claim 1, wherein the at least one additional connecting part can comprise a connecting rod and/or a lever.

7. The constant-volume combustion engine as claimed in claim 1, wherein the rotational coupling can comprise at least one planetary gear stage and two spur gears which roll on one another and which are each assigned to one of the crankshafts.

8. The constant-volume combustion engine as claimed in claim 1, wherein the rotational coupling of the first and second crankshafts has at least one planetary gear stage with at least one spur gear which rolls on at least one internal gear of the planetary gear stage, the spur gear or the internal gear of the at least one planetary gear stage being assigned to one of the crankshafts and the respectively other being assigned to the respectively other crankshaft.

9. A method of using a constant-volume combustion engine as claimed in claim 1 as a generator or for driving a generator, wherein the engine operates a heat and power cogeneration plant or charges the battery of a vehicle.

10. A method for operating a combustion engine, in particular a reciprocating piston engine for generating mechanical energy by way of expansion of a gas or a hot gas from the combustion of the gas mixture or gas/fuel mixture, having at least one piston/cylinder unit, the piston of which is connected to a piston rod, the piston rod being drive-connected to and mounted rotatably with a first eccentricity (d.sub.1) on a first crankshaft, the first crankshaft being coupled to a second crankshaft, wherein the first crankshaft is mounted with a second eccentricity (d.sub.2) on the second crankshaft, the second eccentricity (d.sub.2) being between three and five times as great as the first eccentricity (d.sub.1) and wherein the rotational movements of the coupled crankshafts are superimposed in such a way that the resulting total movement generates, in at least one defined angular section, a substantially constant position of the piston rod and the piston which is connected to it in the piston/cylinder unit.

11. The method as claimed in claim 10, wherein the first and second crankshafts are coupled to one another via at least one connecting part, for example a connecting rod and/or a rocker, the connecting part being capable of transmitting the superimposed movement of the first and second crankshafts to the piston rod, and in that the crankshafts which are coupled to one another rotate relative to one another in the same direction and with a predefined rotational speed ratio.

12. The method as claimed in claim 10, wherein the defined angular section is assigned at least partially to the power or combustion stroke of the combustion engine.

Description

(1) In the figures, diagrammatically:

(2) FIGS. 1a-1c show different views of a constant-volume combustion engine according to the invention, in accordance with the first embodiment,

(3) FIGS. 2a-2c show different views of a constant-volume combustion engine according to the invention, in accordance with the second embodiment, and

(4) FIGS. 3a-3c show different views of a constant-volume combustion engine according to the invention, in accordance with a third embodiment.

(5) FIGS. 1 to 3 show three different embodiments of a constant-volume combustion engine according to the invention. Here, identical features are denoted by the same designations, the numeral 1 being placed ahead of them in the second embodiment according to FIG. 2 and the numeral 2 being placed ahead of them in the third embodiment according to FIG. 3. Furthermore, the a figure in each case shows a sectional view of the respective constant-volume combustion engine according to the sectional line A-A in the associated b figure of the same embodiment of the constant-volume combustion engine. The c figure in each case illustrates the corresponding constant-volume combustion engine in an isometric partially sectioned view.

(6) The constant-volume combustion engine according to FIGS. 1a-c is denoted generally by the designation 10 and, within a housing 12, comprises a piston/cylinder arrangement with a piston 14 which is received displaceably within a cylindrical receiving space 16 for the piston. Here, the piston 14 can be provided in a manner known per se with sealing means on its outer circumference, in order to delimit a working space or combustion space which is as sealed as possible within the cylindrical receiving space 16. Furthermore, the piston 14 is connected via a shaft-shaped connecting part 18 to a piston rod 20, by the shaft 18 being seated rotatably in a corresponding seating section 22 of the piston rod 20.

(7) Furthermore, the piston rod 20 has a second seating section 24 for rotatable connection to a first crankshaft 40 and an intermediate web 26 which connects the seating sections 22 and 24 to one another.

(8) The crankshaft system 28 which comprises a first crankshaft 40 and a second crankshaft 30 is essential to the invention. The two crankshafts 30, 40 in each case have a center longitudinal axis L.sub.1 and L.sub.2, respectively, about which they can rotate. The center longitudinal axes L.sub.1 and L.sub.2 therefore at the same time form the rotational axes for the respective crankshaft. The second crankshaft 30 is supported rotatably within the housing 12 via bearing points 32a and 32b which are customary per se. Said second crankshaft 30 has two eccentrically arranged seating regions 34a and 34b, in which the first crankshaft 40 is seated such that it can be rotated relative to the second crankshaft 30. The eccentric seating regions 34a and 34b are arranged eccentrically in relation to the longitudinal axis L.sub.2 of the second crankshaft 30 and are configured so as to be aligned with one another. Depending on the design of the first crankshaft 40, the seating regions 34a and 34b can be configured with the same size or different sizes. As can be seen clearly in FIG. 1a, the crankshafts 30 and 40 are arranged parallel to one another.

(9) In the first embodiment according to FIGS. 1a-c, furthermore, the second crankshaft 30 is configured as a hollow shaft, an intermediate shaft 36 being arranged in its interior and being configured so as to be fixed to the housing 12 so as to rotate with it. Here, the crankshaft 30 is supported on the intermediate shaft 36 via two bearing points 36a and 36b which are arranged on the inner circumference of the cavity which is defined by the second crankshaft 30. The second crankshaft 30 is therefore supported on the housing 16 to the outside via the outer bearing points 32a and 32b and on the intermediate shaft 36 which is fixed to the housing via the inner bearing points 36a and 36b.

(10) Furthermore, a spur toothing system 38 is configured in the manner of a sun gear on the intermediate shaft 36, which spur toothing system 38 is in engagement with a corresponding gearwheel 48 of the first crankshaft 40. In the embodiment which is shown, the gearwheel 48 is pressed onto the first crankshaft 40, but as an alternative, however, can also be configured directly on said first crankshaft 40 or can be connected to it fixedly so as to rotate with it in some other way.

(11) The first crankshaft 40 is seated eccentrically with respect to the second crankshaft 30 in the circular seating recesses 34a and 34b of said second crankshaft 30 which form the seating region, and is supported on the second crankshaft 30 by way of the bearing points 42a and 42b such that it can be rotated relative to said second crankshaft 30. The eccentricity is specified by way of the spacing d.sub.2 between the center longitudinal axes L.sub.1 and L.sub.2.

(12) Furthermore, the first crankshaft 40 has a shaft head 44 which is seated rotatably within the seating section of the piston rod 20. The shaft head 44 of the crankshaft 40 is of substantially circular configurations, the center point M of the circular shaft head 44 being arranged eccentrically with respect to the longitudinal axis L.sub.1 and therefore the rotational axis of the first crankshaft 40 (the spacing between the center point M and the longitudinal axis L.sub.1 is specified by d.sub.1). Accordingly, the shaft head 44 and therefore also that seating section 24 of the piston rod 20 which surrounds said shaft head 44 perform an eccentric rotational movement relative to the crankshaft 40.

(13) In the following text, the method of operation of the above-described constant-volume combustion engine 10 will be explained in greater detail:

(14) According to the first embodiment of FIGS. 1a-c, the crankshaft arrangement 28 connects the second crankshaft 30 via a planetary gear stage to the first crankshaft 40. In said embodiment, the planetary gear stage comprises two spur gears 38, 48 which are in engagement with one another and roll on one another during a rotational movement. Therefore, the movement of the piston rod 20 is transmitted via the shaft head 44 to the first crankshaft 40 which, as a consequence, is capable of rolling on the spur gear 38 of the intermediate shaft 36 which is fixed to the housing and is thus capable of driving the second crankshaft 30 via the seating recesses 34a and 34b in a rotational movement which rotates about the intermediate shaft 36. Therefore, the second crankshaft 30 is driven by way of the movement of the piston rod 20 and the rotational movement of the first crankshaft 40 about the intermediate shaft 36, since the first crankshaft 40 is arranged eccentrically in the seating recesses 34a and 34b of the second crankshaft 30.

(15) As a result of the specific eccentric arrangement of the first and the second crankshaft relative to one another, a superimposed total rotational movement is transmitted at the shaft head 44 to the piston rod 20 and the piston 14 which is connected to it, which total rotational movement is retarded with respect to a customary movement of the piston during the work stroke, that is to say at the top dead center of the piston 14. The specific eccentric arrangement of the first and the second crankshaft relative to one another likewise achieves a situation where the piston 14 performs an accelerated movement in the region of its bottom dead center.

(16) It can be provided here that the spacing d.sub.2 is approximately four times as great as the spacing d.sub.2. Furthermore, the phase shift of the rotational movement of the first crankshaft 40 with respect to the rotational movement of the second crankshaft 30 can be approximately 90. Finally, it can be provided that the rotational speed ratio of the first crankshaft to the second crankshaft lies at approximately 1 to 2, that is to say the first crankshaft 40 rotates approximately twice as rapidly as the second crankshaft 30.

(17) As a result of the eccentric arrangement of the crankshaft arrangement 28 and the provision of a planetary gear stage, a particularly space-saving arrangement which makes a constant-volume process, as described in the description, possible is provided in the present case.

(18) In contrast to the first embodiment, in the second embodiment according to FIGS. 2a-c, the first crankshaft 130 is not configured as a hollow shaft.

(19) Instead of an intermediate shaft 36 which is fixed to the housing (cf. FIG. 1a), in the second embodiment of a constant-volume combustion engine 110 an internal gear 146 is provided which is likewise arranged within the housing 116 such that it is fixed to the housing and makes rolling of the spur gear 148 of the second crankshaft 140 possible. The remaining method of operation corresponds substantially to the first embodiment, for which reason reference is made to the comments which belong to said first embodiment.

(20) Finally, FIGS. 3a-c show a further design variant, in which a two-sided mounting of the second crankshaft 240 is provided. To this end, the shaft head 244 of the second crankshaft 240 is arranged centrally on the latter and is flanked laterally by two shaft sections 244a and 244b. The latter in each case have, as did the above-described variants of FIGS. 1a-c and 2a-c, a spur gear 248a, 248b which is capable of rolling in each case on an internal gear 246a, 246b which is fixed to the housing. Furthermore, the second crankshaft is also of two-piece configuration in contrast to the above-described embodiments, and comprises the crankshaft 230a and the crankshaft 230b which are arranged in each case laterally with respect to the shaft head 244 of the first crankshaft 240. The remaining method of operation of the third embodiment corresponds as far as possible to the method of operation of the second embodiment according to FIGS. 2a-c, for which reason reference is made to the comments which belong to said second embodiment.