FOUR-STROKE ENDOTHERMIC ENGINE WITH ROTATING DRUM Description
The present invention relates to a four-stroke endothermic engine with rotating drum, having pistons spreading apart with a reciprocating motion. The design of an endothermic engine with a rotating drum, i. e. an engine that does not use a crankshaft for the reciprocating motion of the pistons, like in conventional engines, has always been a fixed idea. It has been pursued through different, more or less successful solutions, which had scarce or short applications, apart from one case, the Wankel engine, produced and patented in the sixties. Many of the patents intended for this aim have proved more suitable to the construction of pumps rather than of actual endothermic engines. Other patents directly solve the problem, yet with rather complex solutions, using either a drum eccentrically positioned relative to the stationary body where it rotates, or a drum rotating within a stationary body having an external cavity acting as a combustion chamber. The present Applicant is already the owner of some solutions in this field, which are not mentioned here to avoid making the specification too heavy. Even though those solutions were valid, they remained in the project state and they have not been produced or applied on a car by a big company in the field. The present invention provides another solution, different from the above-mentioned solutions of the same Applicant.
Said internal combustion engine comprises a drive shaft onto which a cylindrical drum equipped with fixed radial blades is fitted, said shaft being rotatable inside a stationary body, the engine being characterised in that said drum internally defines a cylindrical compression chamber within which two pistons are arranged, which pistons perform a reciprocating rotary motion around the drive shaft to provide for the compression of the combustible mixture; said mixture being introduced into the hollow space defined between the drum and the stationary body, into the cell defined by two subsequent radial blades, and being dragged by the rotary motion of the drum to the burst chamber, the mixture explosion causing rotation of the drum and hence generating the driving force for the whole system.
The invention will now be described in detail with particular reference to the accompanying drawings, in which:
- Fig. 1 is an elevational side view of a longitudinal section of the engine of the invention; i
- Fig. 2 is a front view of a front section of the engine of the invention;
- Fig. 3 is a detailed view of the device actuating the drive cams of the admission gate; and
- Fig. 4 is a schematic view, similar to Fig. 2, of a variant embodiment including lightened pistons.
As it is apparent from the drawings, the engine of the invention essentially comprises: a drive shaft 1; a distribution box 3; a supporting wall 5; a compression chamber 7; a rotating drum 9; a central body 11; and a closing cap 13.
Drive shat 1 is a cylindrical linear axle, having fitted thereon a central gear 15 and, on the opposite side, the aforementioned rotating drum 9 which will be disclosed further on.
Distribution box 3, froming the external portion of the engine and the end support for drive shaft 1, internally contains:
- two distribution shafts 17 and 19, integrally formed with expansion keys 21, 23, better shown in Fig. 2. As shown, said keys 21, 23 have a peculiar, lobed shape. Each shaft has a particular shape in three different regions to perform its tasks. The hatched regions of said shafts 17, 19 have a square cross-sectional shape since drive cams 25, 27, shown in Fig. 3, are to be mounted thereon.
- drive cams 25, 27 for admission gate 29. Such cams are integrally formed at both sides of a central wheel 31 acting as a support, and they have different tasks: one of them provides for opening admission port 33, the other for closing same by actuating gate 29;
- drive gears 35, 37 (only gear 35 is shown), which are fitted on shafts 17, 19, have a diameter twice that of central gear 15 fitted on drive shaft 1, and are in constant mesh with the central gear. The distribution box also acts as a sump for collecting lubricating oil.
Support wall 5, besides performing its support function, includes admission ports 33 through which the gaseous mixture will be sucked. As said, opening and closing are controlled by gate 29, through cams 25, 27. Compression chamber 7 is a cylindrical, hat-shaped chamber, which is to be fastened as shown. Two ejection ports 43, 45 are formed along its side, in diametrically opposite points, and the compressed gaseous mixture will pass to burst chamber 47 through said ports. Two pistons 49, 51, with circular-sector shape, are located within compression chamber 7. The pistons are hinged on drive shaft 1 and their movements are driven by
expansion keys 21, 23. Here, drive shaft 1 only acts as a pivot. Each piston 49, 51 has a particular lobe 53, 55, having only safety functions for protecting admission gate 29 from the high pressure due to compression. It is to be appreciated that such lobe will assist in closing admission port 33, but it will not hinder the passage of the compressed mixture though ej ection ports 43, 45.
Rotating drum 9, better shown in Fig. 2 that, as said, is a front sectional view of the whole central body 11, is the member imparting the motive power to the whole system. It is directly fitted onto drive shaft 1. A plurality of curved blades 61 is provided onto the drum periphery, and they have such a height that said drum is allowed to rotate inside the central body. A small cell 63 with side walls 65, 67 is formed between two consecutive blades, and opening port 69 thereof allows the compressed mixture to pass into burst chamber 47, of which said cell is part together with a small recess of the central body, where ignition plug 71 is arranged. A second cell, wholly similar to the cell described above, is provided on the opposite side and is spaced apart by 180° with respect to the cell described above. The description of that second cell is obviously omitted.
Drum 9 is also integral with the impeller (not shown) of a centrifugal pump for the lubricating oil. Central body 11 is the central portion of the system, and it is shown in cross-sectional view in Fig. 2. It acts as a housing and is equipped with the actual burst chambers 47 and with exhaust manifolds 73, 75.
Closing cap 13 closes the assembly and forms the natural support for the drive shaft. A short description of the operation is now necessary. In cylindrical chamber 7, both peculiar pistons 49, 51 are compelled to perform a reciprocating rotary motion about drive shaft 1 onto which they are hinged. Said motion is determined by the clockwise rotation of expansion keys 21, 23, which in turn are driven by respective gears 35, 37, integral with respective shafts 17, 19. Said gears have a diameter twice the diameter of central gear 15 fitted onto drive shaft 1, and they are in constant mesh with said central gear. Both keys 21, 23 alternatively perform an active and a stand-by function. They are in phase opposition since their angular positions are shifted by 180°, so it is evident that while one key is performing the active function, the other will take the stand-by function and vice versa. During the active period, the key concerned will provide for spacing apart pistons 49, 51
on the one side, and for making them contact on the other side, while the opening and closing movement will be constantly controlled.
In the opening phase, pistons 49, 51 will generate a gap of about 45° into which the gaseous mixture will be sucked through admission port 33. At the same time, on the opposite side, the same pistons 49, 51, in the closing phase, will compress the previously sucked mixture and will send it towards burst chamber 47 through ejection ports 43, 45. Now rotating drum 9 is made to intervene. The drum, by rotating in counterclockwise direction and at a speed twice that of expansion keys 21, 23, will transfer the compressed mixture, through opening port 69, into burst chamber 47, where plug 71 will cause explosion thereof.
The explosion, because of the reaction between the drum and the central body, will cause rotation of drum 9 and hence will generate the motive power for the whole system. After explosion, the gases will expand through blades 61 of drum 9, until they reach exhaust manifold 73, 75, to which combusted gases will be sent. Since the drum, while operating, activates only one burst chamber of the two chambers it is equipped with, and since the drum rotates in opposite direction and at twice the speed of keys 21, 23, each burst chamber will be activated every 180° of rotation, thereby ensuring two active phases at each revolution. The movement of gate 29 is ensured by a drawer 79 sliding on ball guides (see Fig. 3) to reduce friction as much as possible. The opening of the admission port during the suction phase takes place thanks to the operation of cam 25, whereas the fast closing of the same port takes place through return springs 77, without awaiting intervention of the subsequent cam 27. Fig. 4, as stated, shows a variant embodiment of the engine of the invention, where pistons 49, 51 are lightened, i. e. they have a hollow interior. In such a variant embodiment, ducts 81 belonging to the lubrication circuit can pass through the internal cavities of the pistons. It is evident that the above description has been given only by way of non-limiting example, and that changes and modifications are possible without departing from the scope of the invention. For instance, keys 21, 23 could be secured onto the respective shafts 17, 19 through strengthening members. Moreover, in the alternative or in addition to lobes 53, 55 of pistons 49, 51, a longitudinal partition could be provided within the suction duct for the gaseous mixture, in order to protect gate 29 from the high pressure during the burst phase.