TWI841651B - A rotary valve internal combustion engine - Google Patents

Abstract

A rotary valve internal combustion engine comprising a combustion chamber being defined in part by the piston and the combustion end of the cylinder, a valve housing fixed at an outer portion of the combustion end of the cylinder and defining a bore and a rotary valve carried by a ball bearing being rotatable in the bore about a rotary valve axis. The rotary valve is mounted in the valve housing for rotation by the crankshaft through a gear drive train, the drive train having a driven gear rotationally fast with the rotary valve. A gap is provided between the bearing and the driven gear and contains a resilient element to bias the valve into engagement with the bearing. The bearing has a seal between the inner and outer race with a bleed passage to the inlet port to limit combustion gases passing through the bearing to the resilient element.

Description

Rotary valve internal combustion engine

The present invention relates to a rotary valve internal combustion engine, in which the intake and exhaust of combustion gas are controlled by means of a rotary valve.

A known rotary valve internal combustion engine includes: a piston connected to a crankshaft and reciprocating in a cylinder, the cylinder having a combustion end, a combustion chamber partially defined by the piston and the combustion end of the cylinder; a valve cover fixed to the outside of the combustion end of the cylinder, and defining a hole in the valve cover and a rotary valve rotating along a rotary valve shaft in the hole, the rotary valve having a hollow valve body, the hollow valve body having an internal volume to form a part of the combustion chamber, wherein the internal volume of the hollow valve body accommodates the combustion gas during the combustion process, and also has an interface on its wall, which is used to provide fluid flow to the combustion chamber and the self-combustion combustion chamber in sequence through the air inlet and the air outlet in the valve cover when the valve rotates.

The present invention attempts to provide an engine with improved structural features.

According to the present invention, a rotary valve internal combustion engine is provided, which includes a piston connected to a crankshaft and reciprocating in a cylinder, the cylinder having a combustion end, a combustion chamber partially defined by the piston and the combustion end of the cylinder; a valve cover fixed to the outside of the combustion end of the cylinder and defining a hole in the valve cover, and a rotary valve rotating along a rotary valve shaft in the hole, the rotary valve having a hollow valve body, the hollow valve body having an internal volume to form a part of the combustion chamber, wherein the internal volume of the hollow valve body accommodates the combustion gas during the combustion process, and also has a The interface is used to provide fluid flow to the combustion chamber and the self-combustion chamber in sequence through the air inlet and the air outlet in the valve cover when the valve rotates, wherein the rotary valve is installed in the valve cover to rotate through a gear drive system and the crankshaft, and the gear drive system includes a driven gear that can rotate along the rotary valve shaft, and the driven gear rotates rapidly with the rotary valve, wherein a predetermined axial gap is provided between the driven gear and the bearing on which the rotary valve is installed, and the bearing includes a single-turn ball bearing, wherein the space between the inner ring and the outer ring of the bearing is sealed by a seal to prevent the combustion gas from passing through the bearing.

In a preferred embodiment, the space between the inner and outer rings of the bearing is sealed by a seal to substantially restrict the passage of combustion gases through the bearing, wherein the seal is located on the valve side of the single-turn ball bearing to protect the bearing from the effects of combustion gases.

Preferably, the driven gear has an annular strip to align with the inner ring of the bearing, and an axial gap is formed between the annular strip and the inner ring of the bearing.

Preferably, the elastic element is located in the axial gap.

Preferably, the seal is made of metal and in preferred forms includes a wave spring element.

Preferably, the elastic element is annular and coaxial with the rotary valve.

Preferably, the elastic element is a wave spring.

In a preferred embodiment, an exhaust passage is provided to discharge the combustion gas escaping from the space between the valve body and the valve cover back to the air inlet.

1: Piston

2: Cylinder

3: Crankshaft

4: Combustion chamber

5: Valve

5a: Axis

6: Axis

7: Bearings

8: Valve cover

9: Driven gear

10: Drive gear

11: Driving device

12: Drive shaft

13: Lower bearing

14: Shoulders

15: Bevel gear

16:Hollow valve body

17: Tube

18: Upper bearing

19: Content accumulation

20: Volume

21: Interface

22: Next week's edge

23: Wall

24: Wave spring

25: Rolling Balls

26: Seals

28: Inner circle

29: Outer ring

30: Countersunk screws

31: Ring bar

32: Axial clearance

33: Timing pin

34: Timing mark

35: Timing hole

37: Air intake duct

39: Air intake

40: Black arrow

The preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 shows a cross-sectional view of a single-cylinder air-cooled rotary valve internal combustion engine.

Figure 2 is an enlarged schematic diagram of a portion of the rotary valve body and the drive gear.

Figure 3 shows a plan view of the rotary valve drive and driven gears.

Figure 4 shows an enlarged cross-sectional view of the rotary valve and drive gear.

Figure 5a and Figure 5b show the plan view and side view of the wave spring respectively.

Figure 6 shows a perspective view of the valve and driven gear.

Figure 7 shows a perspective view of the valve and ball bearing.

Figure 8 shows the path of combustion gas escape.

Reference is now made to Figure 1, which shows a single cylinder air-cooled engine. The engine contains a cylinder head housing a cylinder 2. The piston 1 is connected to a crankshaft 3 in a conventional manner, and the crankshaft 3 is mounted to rotate in a crankcase 14 to reciprocate in the cylinder 2. The upper portion of the cylinder 2 is sealed by a combustion chamber 4 in the combustion chamber housing. The flow of intake air/fuel mixture and exhaust gas into and out of the combustion chamber 4 is controlled by a rotary valve 5. In this embodiment, the valve 5 can rotate within a valve cover 8 in the combustion chamber housing along an axis 5a that is coaxial with the axis of the cylinder 2. In other embodiments, the rotation axis of the valve body is offset from the axis 5a of the cylinder 2.

At the end remote from the combustion chamber 4, the rotary valve 5 has a concentric drive shaft 6 which carries a single-turn ball bearing 7 which rotatably supports the valve 5 in a valve housing 8. The valve drive shaft 6 is fixed to a coaxial driven gear 9 which engages with a drive gear 10 of a drive device 11 via the driven gear 9, thereby connecting the rotary valve 5 to the crankshaft 3. The drive arrangement 11 comprises a drive shaft 12 which is located in a passage or tube 17 in the cylinder head and is mounted to rotate in an upper bearing 18 adjacent the drive gear 10 and a lower bearing 13 adjacent the crankshaft.

The channel or tube 17 is cast into the cylinder head. The channel or tube 17 is integrally formed with the cylinder head and can be formed by a casting process. The drive shaft 12 carries a bevel gear 15 which engages with a corresponding bevel gear fixed to the crankshaft so as to rotate with the crankshaft 3. The rotation of the crankshaft 3 and therefore the movement of the piston is thus adapted to the rotation of the rotary valve 5 so that the engine runs in a conventional four-stroke cycle. For this purpose, the driven gear 9 has a diameter twice that of the drive gear 10 so that the rotary valve 5 rotates at half the engine speed.

Reference is now also made to FIG. 2 , which shows more details of the rotary valve 5, which includes a generally cylindrical rotary valve body 5, which can rotate around a rotary valve axis 5a and fits tightly and slidingly in the bore of the valve cover 8. The rotary valve 5 has a hollow valve body 16, which has an internal volume 19 to form a part of the combustion chamber. The valve has a generally cylindrical main body portion, which includes the valve body 16 itself, and the diameter of the main body portion is slightly larger than the shaft 6, which forms a shoulder 14, and the inner race 28 of the ball bearing 7 is located on the shoulder 14. The valve body 16 extends into the combustion chamber and has a volume 20 inside it, which forms part of the combustion chamber 4 and is used to contain the combustion gases at all stages of the combustion process. The valve body 19 can be rotatably adapted to fit tightly and slidingly in the hole in the valve cover 8. The valve 5 and the valve cover 8 are formed of aluminum.

The diameter of the shaft 6 portion of the rotary valve 5 is only slightly smaller than the valve body 19 to provide the shoulder 14. The shaft is solid to provide a good path for conducting heat from the valve body 16 to the outside.

During the valve rotation process, the rotating valve body interface 21 allows the fluid to flow sequentially to the valve content volume and from the valve content volume and thus to the fluid flow of the combustion chamber through the air inlet and exhaust ports in the valve cover. In this embodiment, the interface 21 is in the form of a recess, which is formed in the lower peripheral edge 22 of the wall 23 of the valve body, adjacent to the combustion chamber 4, and the recess extends upward from the lower edge of the wall of the valve to form the interface 21 located on the side of the valve.

Referring further to Figures 2 and 3, the connection between the driven gear 9 and the rotary valve 5 is shown. The driven gear 9 is coaxially fixed to the rotary valve 5 by means of countersunk screws 30. The driven gear 9 has a concentric recess which receives the outer end of the shaft 6 and has an annular strip 31 which is aligned with the inner ring 28 of the ball bearing 7. An axial clearance 32 is provided between the annular strip 31 and the inner ring 28 to allow a small degree of axial float, which means that the valve 5 is not clamped on the inner ring 28 and can therefore move slightly radially to accommodate any slight concentric deviation between the bearing 7 and the valve bore in which the rotary valve rotates.

During operation, the forces generated by the combustion gases tend to move the valve body axially relative to the valve cover. In order to prevent the shoulder 14 from hammering against the inner ring 28 of the bearing 7 due to the axial movement of the valve body 16 relative to the inner ring 28 of the bearing, a resilient element in the form of a wave spring 24 biases the driven gear 9 to push the shoulder 14 of the valve body 16 upwards to contact the bottom of the inner ring 28, which would otherwise occur in each combustion cycle, as shown in Figure 4. During operation, there is sufficient force to prevent hammering or vibration between the two components, but the strength is not enough to prevent slight radial movement of the valve body, so it is necessary to accommodate slight misalignment between the valve and the valve cover, which is actually caused by slight differences caused by manufacturing tolerances of the components.

As shown in FIG. 5a and FIG. 5b, the wave spring is composed of a plate-like body that is generally annular. In particular, as shown in FIG. 5b, the wave spring 24 has a plurality of waves over its entire annular length that bend the spring from the radial plane. In this embodiment, the wave spring is formed of spring steel. The spring element may be formed of other materials, designs, or shapes as long as it meets the purpose of being able to provide the required elastic damping effect and being able to cope with the harsh environmental conditions in the engine.

FIG6 shows a schematic perspective view of a rotary valve 5 and a driven gear 9 with a wave spring 24, wherein the wave spring 24 is located between the inner ring 28 of the bearing and the driven gear 9. FIG7 shows a similar schematic perspective view of a rotary valve 5 and a driven gear 9 with a single-turn ball bearing 7 fixed in place. Also as shown in FIG8, the space between the inner ring 28 and the outer ring 29 of the bearing 7 is sealed at its lower edge by a metal seal 26.

In practice it has been found that some combustion gases escape between the interface between the rotary valve body 5 and the valve cover 8. These exhaust gases can pass through the bearing 7 and past the ball 25 and into the chamber containing the driven gear and wave spring to produce carbon deposits which have an adverse effect on the performance and durability of the valve, and the high temperature and corrosion of the hot gases can cause premature failure of the wave spring. To prevent or at least reduce the leakage of combustion gases across the bearing 7, the seal 26 seals the gap between the inner race 28 and the outer race 29 of the bearing, and the seal is made of metal to cope with the harsh environmental conditions. Furthermore, the seal confines the escaping combustion gases and protects the elastic spring from damage or destruction.

Referring now to FIG. 8 which shows an enlarged view of the valve and bearing arrangement, a modification of the intake passage 37 is illustrated, as indicated by the black arrow 40, in which an intake passage 37 leading to the intake port is provided from the narrow annular space 28 between the annular metal seal 26 and the valve cover. This has the advantage that the escaping combustion gas is fed back to the intake port 39 where it is recirculated through the engine to improve the emission performance of the engine.

The timing of the engine is determined by bringing the rotary valve 5 into the correct position relative to the valve gear via the timing pin 33. The drive gear 10 has a timing mark 34 which indicates when the engine is at top dead center. The driven gear 9 connected to the rotary valve has a timing hole 35 suitable for receiving the timing pin 33, and the driven gear has a corresponding timing hole, and the timing pin is inserted into the timing hole to fix the driven gear 9 to the rotary valve 5 to keep the rotary valve at its top dead center position. The countersunk screw 30 is then inserted to fix the driven gear 9 to the rotary valve 5 in the correct timing position, and the countersunk head of the screw 30 engages the end of the timing pin 33 to fix it in place. Other means such as washers on screws 30 may be used to secure timing pin 33 in place.

Because the rotary valve has an interface 21 on its peripheral wall, the mass of the known valve is unevenly distributed around it and unbalanced forces are generated when the rotary valve actually rotates. In another embodiment of the engine, a counterweight or counterweight mass is manufactured in the valve structure, in particular by adding material to the driven gear 9 or removing material from the driven gear 9 at an appropriate location. The embodiment is described for a single-cylinder air-cooled engine, but it should be understood that the present invention is also applicable to multi-cylinder and/or water-cooled engines.

1: Piston

2: Cylinder

3: Crankshaft

4: Combustion chamber

5: Valve

5a: Axis

6: Axis

7: Bearings

8: Valve cover

9: Driven gear

10: Drive gear

11: Driving device

12: Drive shaft

13: Lower bearing

14: Shoulders

15: Bevel gear

16:Hollow valve body

17: Tube

18: Upper bearing

Claims (5)

A rotary valve internal combustion engine comprises: a piston connected to a crankshaft and capable of reciprocating in a cylinder, the cylinder having a combustion end, a combustion chamber partially defined by the piston and the combustion end of the cylinder; a valve cover fixed to the outside of the combustion end of the cylinder, and defining a hole in the valve cover and a rotary valve rotating along a rotary valve shaft in the hole, the rotary valve having a hollow valve body, the hollow The valve body has an internal volume to form a part of the combustion chamber, wherein the internal volume of the hollow valve body accommodates the combustion gas during the combustion process, and also has an interface on its wall portion for providing fluid flow to and from the combustion chamber in sequence through the inlet and exhaust ports in the valve cover when the valve rotates, forming a surface between the main body of the rotary valve and the continuous surface of the hole in the valve cover. The invention relates to a rotary valve having a sealing function, wherein the rotary valve is installed in the valve cover to rotate through a gear transmission system and a crankshaft, wherein the gear transmission system includes a driven gear that can rotate along the rotary valve shaft, and the driven gear rotates rapidly with the rotary valve; a bearing is provided between the driven gear and the valve body, wherein a predetermined axial gap is provided between the driven gear and the bearing on which the rotary valve is installed, and a predetermined axial gap is provided between the driven gear and the bearing on which the rotary valve is installed. An exhaust passage is provided to discharge the combustion gas escaping from the space between the valve body and the valve cover back to the air inlet, and the bearing comprises a single-turn ball bearing having an inner ring and an outer ring, wherein the space between the inner ring and the outer ring of the bearing is closed by a metal seal, and the metal seal is located on a valve side of the bearing, thereby protecting the bearing from the combustion gas and substantially limiting the combustion gas from passing through the bearing. A rotary valve internal combustion engine as described in claim 1, wherein the exhaust port is composed of a drill hole or a groove on the valve hole surface. A rotary valve internal combustion engine as described in claim 1, wherein the driven gear has an annular strip to align with the inner ring of the bearing, and the axial gap is formed between the annular strip and the inner ring of the bearing. A rotary valve internal combustion engine as described in claim 1, wherein the seal comprises an annular elastic element coaxial with the rotary valve. A rotary valve internal combustion engine as described in claim 4, wherein the elastic element is a wave spring.