Rotary Engine Rotor

[0001] The present invention relates to a rotor of a rotary motor. Rotary internal combustion engines are well known and usually include a rotating piston or rotor mounted in a rotatable manner in the housing cavity or in a stator. The rotor and walls of the cavity are shaped such that when the rotor rotates, combustion chambers are formed, the cavity walls further have inlet and outlet ports for air and exhaust gases respectively. Wankel engines are a special form of internal combustion rotary engines, in which the stator has a double-flap epitrochoidal hole, which forms a cavity and further contains end plates that form axially symmetric end walls closing the cavity. The rotor has a body whose outer surface includes three sides of the rotor in the shape of a generally equilateral triangle with sides bent outwards. The rotor is mounted on the eccentric pin of the main shaft and is toothed to rotate in a planetary manner inside the cavity with one third of the rotational speed of the main shaft. The rotor displacement is usually provided by an insert positioned inside the locating hole formed by the inner surface of the body. The insert includes a bearing part and a subdivision gear, the indexed gear meshing with a fixed gear being held by one of the end plates of the engine. The engagement of the subdivision pinion with a fixed toothed wheel limits the rotational speed of the rotor to one third of the rotational speed of the main shaft. The insert must be firmly attached to the rotor body to prevent rotational or axial movement of the insert relative to the rotor body. This allows longer rotor operation at high rotational speeds when the rotor is used inside rotary engines that can be used, for example, in boats, cars, airplanes, stationary engines or compressors. The coupling of the insert to the body should also not adversely affect the operation of the chambers formed by the rotating rotor and cavity. US 4,772,189 describes an air-cooled rotor comprising a rotor body and an insert rigidly fixed together.

[0002] To prevent rotation and axial movement of the insert relative to the rotor body, radially extending channels are made, one on each side of the rotor. Each channel houses a rigid elongated fastening element comprising a pin and comprising a first channel part made in the insert and a second channel part made in the rotor body. Each pin is press-fit to each of the channel parts and has a head that is held in a matching hole in the second channel part adjacent to the outer rotor profile. The dowel head is welded to the rotor body, which provides a substantially gas tight seal. Excess material of the head and the welding material is then removed, so that the remnant of the head and the welding material are aligned with the external surface of the rotor profile.

[0003] US 4,898,522 describes a rotor of a rotary motor with cooling channels and cooling ribs.

[0004] According to the present invention there is provided a rotor of a rotary motor comprising:

one-piece body containing:

an outer surface comprising three sides of the rotor generally equilateral triangle; and an inner surface comprising: a corresponding retaining portion generally made in the center of each side of the rotor, the retaining portions define together at least a part of the locating hole and one retaining portion, with a blind opening extending radially generally from the inner surface of the body, partly towards the outer surface of the body; and a cooling channel extending axially through the body in the region of each apex; an insert disposed in the retaining opening and including a bearing portion and a subdividing gear, the bearing portion having a mounting seat extending generally radially through the insert and ensuring alignment with the blind aperture;

[0005] In the blind hole system, the mounting socket and the fastening element protruding outwardly from the inner position, the outer surface of the rotor body is avoided and the risk of creating a gas leak path between the outer surface and the inner surface of the rotor body is reduced. Another advantage of this arrangement is that the creation of "hot spots" on the outer surface can be reduced. Welding cracks in the outer surface can also be avoided, as welding on said outer surface is not required. There is also no restriction on the shape or profile of the outer surface, because the blind hole does not affect it.

[0006] Preferably, each side of the outer surface of the rotor body has a recess of the combustion chamber formed in the outer surface and passing partially towards the inner surface, and the blind hole passes from the inner surface of the body partially towards the recess of the respective combustion chamber. The recess creates a combustion chamber between the side of the rotor and a cavity formed by an external stator inside which the rotor is placed. Since the blind hole only partially passes in the direction of the combustion chamber, the seat and the fastening element do not affect the recess of the combustion chamber. This provides flexibility in placing a recess in the side of the rotor.

Preferably, the blind hole passes from the inner surface of the body, partly towards the outer surface of the body in a region between the respective cavity of the combustion chamber and the cooling channel. This allows for a longer length of the fastening element, and thus a greater strength of the connection, while ensuring that the blind hole, the mounting seat and the fastening element have no effect on the recess of the combustion chamber.

[0008] Preferably, when said elongated rigid fastening element, blind hole and fastening seat are arranged on each side of the rotor body, each fastening element is seated in a respective blind hole and fastening seat at appropriate positions along the retaining rotor body. This can improve the connection between the body and the insert, while maintaining the balancing of the rotor and allowing stable spinning at high speeds.

[0009] Preferably, each retaining portion has the shape of a circular portion and the retaining portions together form a retaining hole with a substantially circular cross-section. This allows insertion of a substantially circular shape in the retaining hole and can further improve the balancing of the rotor, allowing stable rotation at high rotational speeds.

[0010] Preferably, when each cooling channel is made between a respective pair of fixing parts, the cooling channels and the insert together form cooling passages. The cooling passages allow air to flow to cool the rotor during operation.

[0011] Preferably, each blind opening and mounting seat extends generally transversely to the axis of rotation of the rotor at an angle of 70 ° to 90 ° with respect to the tangent line to the insert. This allows greater flexibility in placing each blind hole and mounting slot and improved manufacturing tolerance during the manufacturing process.

[0012] Preferably, the rotor of the rotary motor is intended for a Wankel engine or for a compressor.

[0013] Embodiments of the invention will now be described in detail only by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of a cross-section of a rotor of a rotary motor in accordance with a first embodiment of the invention;

Figure 2 is a perspective view of the rotor of the rotary motor of Figure 1;

Figure 3 is a schematic representation of a cross-section of a rotor of a rotary motor in accordance with a second embodiment of the invention;

Figure 4 is a perspective view of the rotor of the rotary motor of Figure 3; and

Figure 5 is a schematic representation of a cross-section of a rotor of a rotary motor in accordance with the third embodiment of the invention.

[0014] With reference to Figures 1 and 2, the first embodiment of the invention shows a rotor of a rotary motor 10 comprising a one-piece body 12, an insert 14 and rigid elongated fasteners 16.

[0015] The body 12 comprises an outer surface 18 comprising three sides of the rotor 20 arranged generally in the shape of an equilateral triangle. Each side of the rotor 20 has an externally convex shape. The body 12 further comprises an inner surface 22 comprising three retaining parts 24, each retaining portion being arranged in the center of the respective side of the rotor 20. The retaining parts 24 together form a retaining opening 26. In this

For example, each retaining portion 24 has a blind hole 28 which extends radially from the inner surface 22 partly towards the outer surface 18.

[0016] The body 12 further comprises three cooling channels 30, the respective cooling channel 30 passes axially through the body 12 in the area of ​​each tip 31 of the body 12. Each respective cooling channel 30 has a partially cylindrical shape and is provided with cooling fins 32 which are used for increasing the surface area of ​​said cooling channel 30. Each cooling channel 30 is made between a respective pair of retaining parts 24, so that the cooling channels and the outer surface 36 of the insert 14 together form cooling passages 34. The cooling passages 34 allow the cooling air to pass through the rotor 10.

[0017] The insert 14 is placed in the retaining hole 26 and comprises a bearing portion 38 and a pitching gear 50. The split gear 50 has a machined ring gear and is axially disposed at one end of the rotor 10 as shown in Figure

2. The bearing portion 38 has a mounting seat 40 that extends radially through the insert 14. The insert 14 is positioned inside the retaining opening 26, so that the mounting seat 40 fits into the blind hole 28.

[0018] Each rigid elongated fastening element 16 passes through a corresponding fastening seat 40 and is held in a respective blind hole 28, engaging the insert 14 with the body 12. In this example, each fastening element 16 comprises a fastening pin. Each locating pin 16 is press-fit into the respective mounting socket 40 and blind hole 28 to securely secure the insert 14 to the rotor body 12. Each locating pin 16 is positioned in a respective mounting slot 40 and a blind hole 28 in appropriate positions along the rotor body retainer parts 24 12. This allows stable operation of the rotor at high rotational speeds, while maintaining balancing of the rotor 10. In this example, each respective blind hole 28,

[0019] The one-piece rotor body 12 can be made as a cast iron, while the insert 14 can be made as a blank of a suitable bearing steel or a rod of bearing steel. The retaining pins 16 are preferably made of high quality stainless steel, which reduces the expansion difference between the rotor body 12, the insert 14 and the pins 16. To further secure the insert 14 to the rotor body 12, the head 44 of each dowel 16 can be welded to the insert 14 inside a suitable Bullnose 42. It will be understood that, alternatively, any other shape of the machined opening may be used. Excess welding material

It can then be removed so that the residue of each head 44 and the welding material does not protrude from the inner surface 46 of the insert 14, but it will be understood that the removal of excess welding material is not so important.

[0020] For operation, the rotor 10 is mounted inside a cavity (not shown) in a stator (not shown) on the eccentric pin of the main shaft (not shown). The toothed ring 50 engages with an outer fixed gear (not shown) in a planetary manner and said toothing provides that the rotor 10 rotates at a rotational speed equal to one third of the rotational speed of the main shaft. The rotor 10 and the cavity walls are shaped such that when the rotor rotates, combustion chambers are formed, the cavity walls further have inlet and outlet ports (not shown) for air and exhaust gases, respectively. By arranging each blind opening 28, the mounting socket 40 and the dowel 16, so as to pass outwardly from the inner position, the outer surface 18 of the rotor body 12 is avoided. In this way, the risk of creating a gas leak path between the outer surface 18 and the inner surface 22 of the rotor body 12 is reduced. Another advantage of this arrangement is that the formation of "hot spots" of the outer surface can be reduced. The thermal welding cracks of the outer surface are also avoided because no welding is required on said external surface. There is also no restriction on the shape or profile of the outer surface 18, since the blind hole 28 does not affect this. because no welding is needed on said external surface. There is also no restriction on the shape or profile of the outer surface 18, since the blind hole 28 does not affect this. because no welding is needed on said external surface. There is also no restriction on the shape or profile of the outer surface 18, since the blind hole 28 does not affect this.

[0021] A second embodiment of the invention shows the rotor of the rotary motor 60 for the Wankel engine, as shown in Figures 3 and 4. The rotor 60 of this exemplary application is similar to the rotor 10 of the first embodiment, with the following modifications. The same links are preserved for the same elements.

In this embodiment, the rotor body 60 is further provided with three recesses of the combustion chamber 62, one on each side of the rotor 20. Each cavity of the combustion chamber 62 comprises a combustion pocket formed in the outer surface 18 of the respective side of the rotor 20. Each combustion pocket 62 is generally made around a midpoint of the respective side of the rotor and extends partially towards the inner surface 22 of said side of the rotor. During operation, the combustion pocket 62 forms a combustion chamber between the side of the rotor 20 and a cavity formed in an external stator (not shown) inside which the impeller is placed. In this embodiment, each blind hole 28 passes from the inner surface 22 of the body 12, partly towards the outer surface 18 of the body,

Each tip 31 of the body 12 is provided with a seat of a sealing strip 64. Each seat of the sealing strip 14 is adapted to receive a sealing strip (not shown) which during operation forms a seal between the rotor 10 and the wall of the motor cavity formed by the outer stator.

[0024] A third embodiment of the invention shows a rotor of a rotary motor 70 for a Wankl engine, as shown in Figure 5. The rotor 70 of this embodiment is similar to the rotor 60 of the second embodiment with the following modifications. The same links are preserved for the same parts.

In this embodiment the body 12 has a blind hole 72, a mounting socket 40 and a locating pin 74 generally at the mid point of each side of the rotor 20. Each blind hole 72 extends generally radially from the inner surface 22 of the body 12 partly towards the respective combustion pocket 62 Each retaining pin 74 passes through a suitable mounting socket 40 and is placed in a corresponding blind hole 72 engaging the insert 14 with the body 12. Each blind hole 72 and the corresponding dowel 74 have no effect on the combustion pocket 62. In this embodiment, because each blind hole 72 only partially passes in the direction of the combustion pocket 62, each fixing pin 74 and each blind hole 72 does not affect the combustion pocket.In this way, the flexibility of the arrangement and size of the pocket 62 in the side of the rotor 20 can be obtained.

Małgorzata Trejgis Patent attorney