HK1191077B - Rotary engine rotor - Google Patents

Description

Rotary engine rotor

The present invention relates to a rotary engine rotor.

Rotary internal combustion engines are well known and typically include a rotary piston or rotor rotatably mounted in a cavity in a housing or stator. The rotor and the walls of the cavity are shaped so that a combustion chamber is formed when the rotor rotates, the walls of the cavity also being arranged with inlet and outlet ports for air and exhaust gases, respectively. The Wankel engine is a particular form of rotary internal combustion engine in which the stator is provided with a double roots epitrochoidal barrel (two-lobe epitrochoidal bore) forming a cavity, and further includes end plates forming axially spaced end walls closing the cavity. The rotor is provided with a body comprising an outer surface comprising three rotor sides of generally equilateral triangular cross-sectional shape with outwardly curved sides. The rotor is mounted on an eccentric journal of the main shaft and is driven by a gear to rotate the main shaft in a planetary manner in the cavity for one third of a revolution. The drive of the rotor is typically provided by means of an insert which is received in a locating hole provided by the inner surface of the body. The insert comprises a support portion and an indexing gear (indexingear) arranged to engage a fixed gear, the fixed gear being supported by one of the engine end plates. The engagement of the indexing gear with the fixed gear limits the rotation of the rotor to one third of one revolution of the main shaft. It is desirable that the insert be securely fixed to the body of the rotor to prevent rotational or axial movement of the insert relative to the rotor body. This may enable the rotor to be operated at high rotational speeds for long periods of time, for example when used in a rotary engine, such as may be used in a boat, automobile, aviation aircraft, stationary engine or compressor. The coupling of the insert to the body should also not deleteriously interfere with the working operation of the chamber formed by the rotating rotor and the cavity.

US4772189 describes an air-cooled rotor comprising a rotor body and an insert rigidly fastened together.

US4898522 describes a rotary engine rotor with cooling channels and coolant ribs.

According to an aspect of the present invention, there is provided a rotary engine rotor comprising:

a one-piece body comprising:

an outer surface comprising three rotor sides arranged in a substantially equilateral triangle shape;

an inner surface comprising: respective locating portions, generally provided at a midpoint of each rotor side, the locating portions together defining at least part of the locating aperture, and one locating portion being provided with a blind bore extending generally radially from the inner surface of the body partially towards the outer surface of the body; and a cooling passage disposed axially through the body in each apex region;

an insert disposed in the locating bore and comprising a support portion and an indexing gear, the support portion being arranged with a fixing sleeve extending generally radially through the insert and arranged to align with the blind bore; and

a rigid elongate fixation member disposed through the fixation sleeve and at least partially received in the blind bore to thereby couple the insert to the body.

By arranging the blind hole, the fixing sleeve and the fixing member to extend outwardly from the inner position, the outer surface of the rotor body can be prevented from cracking, and the risk of gas leakage paths in the form of gas between the outer surface and the inner surface of the rotor body can be reduced. A further advantage of this construction is that the formation of "hot spots" on the outer surface can be reduced. It is also possible to avoid weld thermal cracking of the outer surface as if there were no weld on the outer surface. The shape or profile of the outer surface is unconstrained when the blind holes do not affect the outer surface.

Preferably, each rotor side of the body outer surface is provided with a combustion chamber recess formed in the outer surface and extending partially towards the inner surface, and the blind bore is further arranged to extend from the inner surface of the body partially towards the respective combustion chamber recess. The recess is arranged to form a combustion chamber between the rotor side and a cavity provided by an outer stator in which the rotor is seated for receiving the rotor in use. Since the blind hole extends only partially towards the combustion chamber, the sleeve and the fixing member do not influence the combustion chamber recess. This may provide flexibility in the location of the recess in the rotor side.

Preferably, the blind bore extends from the inner surface of the body partially towards the outer surface of the body substantially in the region between the respective combustion chamber recess and the cooling channel. This may allow the length of the fixation member and thus the coupling strength to be maximized while ensuring that the blind hole, the fixation sleeve and the fixation member do not affect the combustion chamber recess.

Preferably, the rigid elongate fixing member, the blind bore and the fixing sleeve are provided on each side of the rotor body, each fixing member being received in a respective blind bore and fixing sleeve in a respective position along the positioning portion of the rotor body. This may improve the engagement between the body and the insert while maintaining the balance of the rotor and allowing stable rotation at high rotational speeds.

Preferably, each locating portion is part-circular in shape and the locating portions together define a locating hole of substantially circular cross-section. This enables the locating holes to receive the substantially circular inserts and may further improve the balance of the rotor, allowing stable rotation at high rotational speeds.

Preferably, each cooling channel is provided between a respective pair of locating portions, the cooling channels and the insert together forming a cooling passage. The cooling passages allow air flow for cooling the rotor during operation.

Preferably, each blind hole and the fixed sleeve extend substantially transversely to the axis of rotation of the rotor at an angle of from 70 ° to 90 ° to tangential with respect to the insert. This may increase the flexibility of positioning each blind hole and the fixing sleeve and obtain improved manufacturing tolerances during the manufacturing process.

Preferably, the rotary engine rotor is used for a Wankel engine or compressor.

Some embodiments of the invention are described below, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a rotary engine rotor according to a first embodiment of the present invention;

FIG. 2 is a perspective view of the rotary engine rotor shown in FIG. 1;

FIG. 3 is a cross-sectional view of a rotary engine rotor according to an embodiment of the present invention;

FIG. 4 is a perspective view of the rotary engine rotor shown in FIG. 3;

fig. 5 is a cross-sectional view of a rotary engine rotor according to a third embodiment of the present invention.

Referring to fig. 1 and 2, a first embodiment of the present invention provides a rotary engine rotor 10 including a one-piece body 12, an insert 14, and a rigid elongated stationary member 16.

The body 12 includes an outer surface 18 that includes three rotor sides 20 arranged in a generally equilateral triangular shape. Each rotor side 20 is shaped to curve outwardly. The body 12 also includes an inner surface 22 that includes three locating portions 24, each of which is generally disposed at a midpoint of a respective rotor side 20. The locating portions 24 together partially define a locating aperture 26. In this example, each locating portion 24 is provided with a blind bore 28 extending generally radially from the inner surface 22 partially towards the outer surface 18.

The body 12 further comprises three cooling passages 30, a respective cooling passage 30 being axially disposed through the body 12 in the region of each apex 31 of the body 12. Each respective cooling channel 30 is of part-cylindrical shape and is provided with cooling fins 32 arranged to increase the surface area of said cooling channel 30. Each cooling channel 30 is disposed between a respective pair of the locating portions 24 such that the outer surface 36 of the insert 14 and the cooling channel together form a cooling passage 34. The cooling passages 34 allow cooling air to flow through the rotor 10.

The insert 14 is disposed in the positioning hole 26 and includes a support portion 38 and an indexing gear 50. The indexing gear 50 comprises a machined ring gear and is disposed axially at one end of the rotor 10, as shown in figure 2. The support portion 38 is provided with a fixed sleeve 40 which extends generally radially through the insert 14. The insert 14 is disposed in the locating hole 26 such that the retaining sleeve 40 is disposed in alignment with the blind hole 28.

Each rigid elongated fixation member 16 is disposed through a respective fixation sleeve 40 and is received in a respective blind bore 28 to thereby couple the insert 14 to the body 12. In this example, each of the fixing members 16 includes a fixing pin. Each fixation pin 16 is drive-mated with a respective fixation sleeve 40 and blind bore 28 to provide a secure coupling of the insert 14 to the rotor body 12. Each fixing pin 16 is received in a respective fixing sleeve 40 and blind bore 28 and is located in a respective position along the locating portion 24 of the rotor body 12. This enables stable operation of the rotor at a high rotational speed by maintaining the balance of the rotor 10. In this example, each respective blind hole 28, fixing sleeve 40 and fixing pin 16 is arranged to extend at an angle of substantially 90 ° to tangential with respect to the insert 14. The respective blind holes 28, the fixing sleeve 40 and the fixing pin 16 may extend at other angles if desired, but preferably the fixing pin does not extend at an angle of less than 70 ° to tangential with respect to the insert 14. In this embodiment, each blind hole 28 may be positioned anywhere along the inner surface 22 between the cooling passages 24. This may increase the flexibility of positioning each blind hole and the fixing sleeve and achieve improved manufacturing tolerances during the manufacturing process.

The rotor body 12 may be manufactured as an iron casting and the insert 14 may be manufactured as a forging from a suitable bearing steel or may be formed from a rod of bearing steel. The fixing pin 16 is preferably made of high grade stainless steel so that the expansion difference between the rotor body 12, the insert 14 and the pin 16 is minimized. To further secure the insert 14 to the rotor body 12, the head 44 of each securing pin 16 may be welded to the insert 14 in the corresponding outer rounded (bull rounded) hole 42. It should be understood that any other machined shaped hole may alternatively be used. Excess weld material may be subsequently removed such that the remainder of each head 44 and weld material are flush with the inner surface 46 of the insert 14, although it will be understood that it is not necessary to remove excess weld material.

In use, the rotor 10 is mounted in a cavity (not shown) in a stator (not shown) on an eccentric journal of a main shaft (not shown). The ring gear 50 is arranged to engage an externally fixed gear (not shown) in a planetary manner, said engagement ensuring that the rotor 10 rotates for one third of a revolution of the main shaft. The rotor 10 and the walls of the cavity are shaped so that a combustion chamber is formed when the rotor rotates, the walls of the cavity being further provided with inlet and outlet ports (not shown) for air and exhaust gases, respectively. By providing each of the blind holes 28, the fixing sleeve 40 and the fixing pins 16 to extend outwardly from an inner location, the outer surface 18 of the body 12 of the rotor 10 is prevented from cracking. In this way, the risk of forming a gas leakage path between the outer surface 18 and the inner surface 22 of the rotor body 12 is reduced. A further advantage of this configuration is that the formation of "hot spots" on the outer surface can be reduced. It is also possible to avoid weld thermal cracking of the outer surface as if there were no weld on the outer surface. The shape or contour of the outer surface 18 is not constrained when the blind holes 28 do not affect the outer surface.

A second embodiment of the invention provides a rotary engine rotor 60 for a Wankel engine, as shown in fig. 3 and 4. The rotor 60 of this embodiment is similar to the rotor 10 of the first embodiment, but with the following modifications. The same reference numerals are maintained for corresponding features.

In this embodiment, the body 12 of the rotor 60 is additionally provided with three combustion chamber recesses 62, one on each rotor side 20. Each combustor recess 62 includes a combustion cavity formed in the outer surface 18 of the respective rotor side 20. Each combustion cavity 62 generally extends about a midpoint of the respective rotor and generally extends partially toward the rotor-side inner surface 22. In use, the combustion cavity 62 is arranged to form a combustion chamber between the rotor side 20 and a cavity provided by an outer stator (not shown) in which the rotor is seated for accommodation. In this embodiment, each blind bore 28 extends from the inner surface 22 of the body 12, partially toward the outer surface 18 of the body, generally toward the region between the respective combustion cavity 62 and the cooling passage 30. This allows the length of the retaining pin 16 and the strength of the attachment of the insert 14 to the body 12 to be maximized while ensuring that the blind bore 28, retaining sleeve 40 and retaining pin 16 do not interfere with the combustion cavity 62.

Each apex 31 of the body 12 is also provided with a sealing band sleeve 64. Each sealing band sleeve 64 is arranged to receive a sealing band (not shown) which in use forms a seal between the rotor 10 and the wall of the engine cavity provided by the outer stator.

A third embodiment of the invention provides a rotary engine rotor 70 for a Wankel engine, as shown in fig. 5. The rotor 70 of this embodiment is similar to the rotor 60 of the second embodiment, but with the following modifications. The same reference numerals are maintained for corresponding features.

In this embodiment, the body 12 is provided with a blind bore 72, a fixing sleeve 40 and a fixing pin 74, typically at the midpoint of each rotor side 20. Each blind hole 72 is arranged to extend generally radially from the inner surface 22 of the body 12, partially toward the respective combustion cavity 62. Each securing pin 74 is disposed through a respective securing sleeve 40 and is received in a respective blind bore 72 to thereby couple the insert 14 to the body 12. Each blind hole 72 and corresponding retainer pin 74 do not interfere with the combustion cavity 62. In this embodiment, each of the retaining pins 74 and each of the blind holes 72 do not affect the combustion cavity because each of the blind holes 72 extends only partially toward the combustion cavity 62. This improves the flexibility with regard to the position and size of the cavity 62 in the rotor side 20.

Claims (8)

1. A rotary engine rotor comprising:

a one-piece body (12) comprising:

an outer surface (18) comprising three rotor sides (20) arranged in a substantially equilateral triangle shape;

an inner surface (22) comprising: respective locating portions (24) disposed generally at a midpoint of each rotor side (20), the locating portions together defining at least part of a locating aperture (26), and one locating portion being provided with a blind aperture (28) extending generally radially from the inner surface of the body partially towards the outer surface (18) of the body; and a cooling channel (30) disposed axially through the body in each apex region;

an insert (14) disposed in the locating bore (26) and comprising a support portion (38) and an indexing gear (50), the support portion being provided with a fixing sleeve (40) extending generally radially through the insert and disposed in alignment with the blind bore; and

a rigid elongate fixing member (16) is provided through the fixing sleeve (40) and at least partially received in the blind bore to thereby couple the insert to the body.

2. A rotor according to claim 1, wherein each rotor side (20) of the outer surface of the body (12) is provided with a combustion chamber recess (62) formed in the outer surface and extending partly towards the inner surface, the blind hole (28) being further arranged to extend from the inner surface of the body partly towards the respective combustion chamber recess.

3. The rotor of claim 2, wherein the blind holes (28) extend from the inner surface of the body partially towards the outer surface of the body substantially in the region between the respective combustion chamber recess (62) and the cooling channel.

4. A rotor according to any preceding claim, wherein the rigid elongate fixing member (16), blind holes and fixing sleeves are provided on each side of the rotor body, each fixing member being received in a respective blind hole and fixing sleeve in a respective position along a locating portion of the rotor body.

5. A rotor as claimed in claim 1, in which each locating portion is part-circular in shape and the locating portions together define a locating hole of substantially circular cross-section.

6. A rotor according to claim 1, wherein each cooling channel is provided between a respective pair of locating portions, the cooling channels and the inserts together forming a cooling passage.

7. A rotor according to claim 1, wherein each blind hole and the fixing sleeve extend transversely to the axis of rotation of the rotor at an angle of 90 ° to tangential relative to the insert.

8. The rotor of claim 1, wherein the rotary engine rotor is for a Wankel engine or compressor.