Axial flow internal combustion engine
The axial-flow internal combustion engine addresses complexity and maintenance issues by eliminating the crankshaft and optimizing the piston assembly, resulting in a compact, efficient engine with high power-to-weight ratio and reduced vibration.
Patent Information
- Application Number
- JP2024572305
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-06-09
- Filing Date
- 2023-06-08
- Publication Date
- 2025-07-08
AI Technical Summary
Existing one-stroke internal combustion engines face challenges such as complexity, high part count, maintenance accessibility issues, and a need for improved power-to-weight ratio and specific output.
An axial-flow internal combustion engine design with a single power cam, reduced components like a crankshaft, and optimized piston assembly with a cam follower and counter cam, allowing for a compact, efficient, and robust operation with high power-to-weight ratio.
The design achieves a compact, lightweight engine with low vibration, high volumetric efficiency, and improved cooling capacity, reducing costs and enhancing performance in applications like model airplanes and automobiles.
Smart Images
Figure 2025521223000001_ABST
Abstract
Description
Technical Field
[0001] This application claims the benefit of European Patent Application Publication No. 22382557.1 filed on June 9, 2022.
[0002] The present disclosure relates to an engine. More specifically, the present disclosure relates to an axial flow internal combustion engine. The internal combustion engine of the present invention can be applied to various uses such as automobiles, flying bodies such as model airplanes, and others.
Background Art
[0003] The axial flow internal combustion engine of the present invention may be referred to as a one-stroke combustion engine. One-stroke internal combustion engines are known in the art. In a one-stroke internal combustion engine, combustion occurs once per piston stroke. The intake stroke, compression stroke, power stroke, and exhaust stroke occur in one revolution of the output shaft or crankshaft. Each piston stroke is a power stroke such that only one power stroke is required to continuously rotate the output shaft or crankshaft to complete a full cycle.
[0004] An example of a one-stroke internal combustion engine is disclosed in US Patent Application Publication No. 20030121482 (A1). This internal combustion engine includes a combustion chamber and a compression chamber. A compression member is provided in the compression chamber to define a first sub-combustion chamber and a second sub-combustion chamber. A piston is slidably disposed in the combustion chamber in communication with the compression member to define the first sub-combustion chamber and the second sub-combustion chamber. The movement of the piston towards the first sub-combustion chamber allows the first fuel-air mixture to flow from the second sub-combustion chamber into the second sub-combustion chamber, draws the second fuel-air mixture into the first compression chamber, and enables subsequent combustion in the second sub-combustion chamber. The movement of the piston towards the second sub-combustion chamber allows the second fuel-air mixture to flow from the first sub-combustion chamber into the first sub-combustion chamber, draws the third fuel-air mixture into the second compression chamber, and enables subsequent combustion in the first sub-combustion chamber.
[0005] A further example of a one - stroke internal combustion engine is disclosed in U.S. Patent Application Publication No. 2016025001 (A1). The one - stroke internal combustion engine of this example comprises an intake chamber, a compression chamber, a combustion chamber, and an exhaust chamber operating in a linear, rotary, or opposed - piston configuration. The crankshaft is driven when the pistons are alternately fired.
[0006] European Patent No. 3066312 (B1), filed by the same applicant as this application, refers to an opposed - piston engine that can complete the entire cycle in just one go. For this purpose, power cams facing each other are connected to their respective rotating shafts, and the reciprocating motion of the pistons acting on the power cams gives a rotational motion to the rotating shafts to drive the engine.
[0007] Axial - flow engines or barrel engines, such as those disclosed in U.S. Patent No. 1042018, having cylinders arranged around and parallel to a central shaft, like the chambers in the cylinder of a revolver, are known in the art. Such prime movers have a small front area with very good balance and excellent compactness, but problems such as being difficult to access for maintenance are usually seen in the swash plates used to convert the piston thrust into rotational motion.
[0008] Known one - stroke internal combustion engines have been shown to offer several important advantages such as smaller displacement and lower emissions, but there remains a need for a simpler engine that requires far fewer auxiliary parts, higher specific output, and higher power - to - weight ratio. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION
[0009] This specification discloses an axial - flow internal combustion engine that at least meets the above - mentioned needs and provides further advantages and benefits. MEANS FOR SOLVING THE PROBLEMS
[0010] The axial-flow internal combustion engine of the present invention includes at least one cylinder, for example, two or four cylinders. Other suitable numbers of cylinders are also possible. The cylinders can be arranged to operate in any desired position, such as horizontally, vertically, or inclined.
[0011] The piston assembly is slidably received within each cylinder. Thus, the axial-flow internal combustion engine of the present invention includes the same number of piston assemblies as cylinders. The piston assembly defines a combustion chamber and a pump chamber within the cylinder. Since the pump chamber within the cylinder of the engine of the present invention is axially arranged with respect to the combustion chamber, it is referred to herein as an axial-flow internal combustion engine. An engine mount is provided to support the cylinder(s). The engine mount may have an opening for receiving the piston body.
[0012] The pump chamber is for sucking air to be fed into the combustion chamber. The combustion chamber is for compressing a fuel / air / oil mixture in one stroke of the piston assembly and then detonating the compressed fuel / air / oil mixture.
[0013] The piston assembly includes a piston head, a piston body, and a connecting rod. The connecting rod has a first end connected to the piston head. A cam follower is attached to the piston body. The cam follower can be, for example, a roller rotatably attached to the piston body.
[0014] The piston head is preferably in the shape of a frustum of a cone. The connecting rod is connected to the piston head and the piston body such that its oscillation is restricted. Thus, the load is supported by the piston body rather than the piston head, there is no side load on the cylinder, and thus wear is less. The fitting of the piston assembly into the cylinder is facilitated, and the opening and closing of the ports are more effective.
[0015] A single power cam is provided. The above-mentioned cam follower provided at the second end of the connecting rod is intended to directly contact, i.e., roll on, the surface of the single power cam. Preferably, a roller bearing is provided to rotate the single power cam.
[0016] The piston assembly moves along a first direction within the cylinder, draws a fuel / air / oil mixture into the pump chamber through the intake port while the transfer port and the exhaust port are closed, then moves along a second opposite direction to send the fuel / air / oil mixture into the combustion chamber through the transfer port, then moves again along the first direction in which the fuel / air / oil mixture is compressed by the piston assembly within the combustion chamber, and then, upon ignition of the compressed fuel / air / oil mixture, moves again along the second direction within the cylinder to perform a power stroke and is configured to open the exhaust port so that combustion gases are exhausted from the combustion chamber. Then, a new fuel / air / oil mixture is sent back into the pump chamber for a subsequent cycle.
[0017] The displacement of the piston assembly within the cylinder along the second opposite direction causes the cam follower to roll on the surface of the single power cam, rotating the single power cam. Consequently, the output shaft connected to the single power cam is rotated. This is repeated for subsequent strokes of the piston assembly.
[0018] A counter cam may be provided on the output shaft to receive a corresponding counter cam follower attached to the piston body coaxially with the cam follower of the piston assembly. The diameter of the counter cam is smaller than that of the power cam. The counter cam is for preventing the piston assembly from losing contact with the single power cam.
[0019] With the above configuration, the crankshaft becomes unnecessary, and as a result, an advantageous compact design is achieved with a high power-to-weight ratio. By providing a single power cam, the mass balance is improved, and an efficient and robust engine with low vibration is obtained.
[0020] Within the scope of the present disclosure, one stroke refers to an engine that requires one single power stroke to rotate the power cam 180° to complete a cycle.
[0021] The cam follower may be provided with at least one channel for the passage of lubricant. Also, the cam follower may preferably be arranged to act in proximity to the central region of the surface of a single power cam. Other configurations are possible.
[0022] As described above, a plurality of cylinders may be provided, and each cylinder has a corresponding piston assembly slidably received therein. In that case, a single power cam is associated with all the piston assemblies. Also in this case, within each cylinder, a pump chamber and a combustion chamber as described above are defined by each piston assembly.
[0023] The cylinder may include a single crankcase that is part of the pump chamber. The single crankcase is associated with the piston assembly. A common crankcase for the cylinders may be provided. The common crankcase may be integrally formed with the engine mount or may be a separate component.
[0024] The fuel control means is preferably provided to adjust the amount of fuel and / or air flowing into the cylinder. The fuel control means may be, for example, at least one carburetor or a fuel injection system. In either case, when provided, it may be advantageous for the fuel control means to be arranged within the common crankcase described above.
[0025] For the intake of fuel / air / oil mixture into the pump chamber of the cylinder, at least one intake port may be provided. For the flow of fuel / air / oil mixture from the pump chamber of the cylinder to the combustion chamber, at least one transfer port may be provided. For the exhaust of combustion gases from the engine, at least one exhaust port may be provided. The exhaust port may preferably be arranged to open before the transfer port opens and close after the transfer port closes.
[0026] Advantageously, one or more longitudinal guides may be provided to guide the piston body when the piston body of the piston assembly moves within the cylinder. Optimally, at least one longitudinal guide provided at the outermost part of the engine mount is larger than other longitudinal guides arranged at other positions of the piston assembly.
[0027] In the axial flow internal combustion engine described above, the clearance volume, i.e., the part of the cylinder volume not swept by the piston, is advantageously very small. This results in a high compression ratio, high volumetric efficiency, and improved cooling capacity. It has been found that the cost is significantly lower compared to a standard internal combustion engine for the same output. The engine of the present invention is lightweight and easily spins up, which is beneficial in flying objects such as model airplanes. The engine of the present invention also finds advantageous applications in automobiles and many other things.
[0028] A non-limiting example of the axial flow internal combustion engine of the present invention will be described below with reference to the accompanying drawings.
Brief Description of the Drawings
[0029]
Figure 1
Figures 2-3
Figures 4-5
Figure 6a
Figure 6b
Figures 6c-d
Figures 7-10
Figures 9a-c
Figures 11-12
Figures 13-14
Figures 15-16
Figures 17-18
DETAILED DESCRIPTION OF THE INVENTION
[0030] Non-limiting examples of an axial flow internal combustion engine 10 for a model airplane are shown in FIGS. 1-16 and described below.
[0031] As shown in FIGS. 1 and 2, the axial flow internal combustion engine 10 includes four cylinders 100, each having a cylinder head 250. The cylinders 100 are supported by an engine mount 240 as shown in FIGS. 1-3. Of course, depending on the specific application of the engine 10, a different number of cylinders 100 is possible. As shown in FIG. 6, the engine mount 240 has an opening 500 suitable for receiving the piston body 112. The piston body 112 can thus be completely received within the engine mount 240. The opening 500 is defined by spaced-apart walls 510 inside the engine mount 240.
[0032] As shown in FIGS. 4 to 5, within each cylinder 100, a piston assembly 110 is slidably received. The piston assembly 110 is shown in detail in FIGS. 6 to 10. In use, the piston assembly 110 reciprocates along the longitudinal axis L of the cylinder 100 shown in FIGS. 13 and 14.
[0033] As shown in FIGS. 6a to 10, the piston assembly 110 includes a piston head 111, a piston body 112, and a connecting rod 135. A cam follower 150 is attached to the piston body 112. In use, the connecting rod 135 connects the piston head 111 to the piston body 112 as shown in FIGS. 1 to 3. In particular, referring to FIGS. 9a, 9b, and 9c, the connecting rod 135 has one end connected to the piston head 111 via a connecting clip 116. The connecting clip 116 has two arms as shown in FIG. 9b. In use, the arms of the connecting clip 116 pass through an opening 117 formed in a connecting body 118 formed inside the piston head 111. Next, as shown in FIGS. 9a, 9b, and 9c, the arms of the connecting clip 116 are received in an annular groove 119 formed in the above-mentioned end portion of the connecting rod 135 and pressed against the annular groove 210. In this way, the connecting rod 135 is connected to the piston head 111 with little freedom of swing.
[0034] As shown in FIG. 6b, each piston assembly 110 defines a combustion chamber 200 and a pump chamber 300 within the corresponding cylinder 100.
[0035] Since the combustion chamber 200 is configured to receive a fuel / air / oil mixture compressed by the piston assembly 110 in one stroke of the combustion engine 10, it may also be referred to as a compression chamber in this specification.
[0036] The pump chamber 300 is arranged axially with respect to the combustion chamber 200 along the longitudinal axis L of the cylinder 100. Since the pump chamber 300 is configured to draw air from the common crankcase 160 into the combustion chamber 200 during the stroke of the combustion engine 10, it can also be called a scavenging chamber.
[0037] Here, referring to FIGS. 6a to 10, the piston assembly 110 is shown with the piston head 111 connected to the piston body 112 via the connecting rod 135 as described above. The connecting rod 135 has a first end connected to the piston head 111 and a second end connected to the piston body 112.
[0038] A plurality of parallel channels 113, shown in detail in FIGS. 9 and 10, are provided in the piston body 112. The channels 113 are provided with ports 114 for the delivery of coolant and lubricant. The channels 113 in the piston body 112 are configured to receive the longitudinal guides 115 formed in the engine mount 240 as shown in FIG. 16. In use, the longitudinal guides 115 guide the piston body 112 when the piston body 112 moves within the engine mount 240. The longitudinal guides 115 located at the outermost part of the engine mount 240 are larger than the other longitudinal guides 115 located at other positions of the engine mount 240.
[0039] As shown in FIGS. 17 and 18, a single power cam 400 is provided. The single power cam 400 is attached to the output shaft 440. The output shaft 440 is attached to the propeller carrier as shown in the figure.
[0040] The above-described cam follower 150 of each piston assembly 110 is intended to directly abut against the surface 410 of a single power cam 400. In particular, the cam follower 150 is arranged to act near the central region of the surface of the single power cam 400. During operation, the displacement of the piston assembly 110 within the cylinder 100 causes the cam follower 150 of the piston assembly 110 to roll on the surface 410 of the single output cam 400, rotating the single power cam 400 together with the output shaft 440. The single power cam 400 is rotatably supported by a roller bearing 430 as shown in FIG. 4.
[0041] As a result of the above configuration, a crankshaft is not required, and thus a compact design is achieved that has a high output-to-weight ratio and an improved mass balance with low vibration.
[0042] Referring to FIGS. 17 and 18, a counter cam 450 is formed on the output shaft 440. The counter cam 450 is intended to receive a corresponding counter cam follower 455. The opening 500 of the engine mount 240 is suitable for receiving the counter cam 450. As shown in FIGS. 7 to 10, the counter cam follower 455 is attached to the piston body 112 coaxially with the cam follower 150 of the piston assembly 110. As shown in FIGS. 7 to 10, the diameter of the counter cam 450 is smaller than the diameter of the power cam 400. The counter cam 450 is for preventing the piston assembly 110 from losing contact with the single power cam 400.
[0043] Each cylinder 100 includes a single crankcase that is part of the pump chamber 300. Further, as shown in FIGS. 1 and 3, the above-described common crankcase 160 that is part of the engine mount 240 is also provided.
[0044] Fuel control means 170 is provided in the above-described common crankcase 160 to adjust the amount of fuel and / or air flowing into the cylinder 100, particularly into the pump chamber 300 of the cylinder 100. In the non-limiting example shown, the fuel control means 170 comprises one or more carburetors. Other fuel control means 170 (e.g., based on fuel injection) are also possible.
[0045] The intake of the fuel / air / oil mixture into the pump chamber 300 is effected through an intake port 180 formed within the engine mount 240, as shown in FIGS. 15 and 16. A transfer port 185 is provided for the flow of the fuel / air / oil mixture from the pump chamber 300 within the cylinder 100 to the combustion chamber 200, as shown in FIGS. 6c and 6d. The exhaust port 190 shown in FIGS. 6c, 13, and 14 is also provided to exhaust combustion gases from the engine 10 through a corresponding exhaust pipe 230. The exhaust port 190 is arranged to open before the transfer port 185 opens and to close after the transfer port 185 closes.
[0046] During operation, the piston assembly 110 first moves along the longitudinal axis L of the cylinder 100 in a first direction within the cylinder, drawing fuel / air / oil mixture from the vaporizer 170 through the intake port 180 into the pump chamber 300 while the transfer port 185 and the exhaust port 190 are closed. Next, the piston assembly 110 moves along the longitudinal axis L of the cylinder 100 in a second opposite direction, feeding the fuel / air / oil mixture through the transfer into the combustion chamber 200. Next, the piston assembly 110 moves again in the first direction, and the fuel / air / oil mixture is compressed within the combustion chamber 200 by the piston assembly 110. Finally, the piston assembly 110 moves in a second direction within the cylinder 100 by ignition of the compressed fuel / air / oil mixture by the spark plug 270 to perform a power stroke, and the exhaust port 190 is opened so that the combustion gases are exhausted from the combustion chamber 200 through the exhaust pipe 230. Thereafter, a new fuel / air / oil mixture is fed again into the pump chamber 300 for a subsequent cycle. This is repeated for subsequent strokes of the piston assembly 110, rolling the cam follower 150 on the surface 410 of a single power cam 400, resulting in rotation of the single power cam 400 and thus the output shaft 440 connected to the power cam 400.
[0047] As the piston assembly 110 moves within the cylinder 100, the transfer port 185 and the exhaust port 190 are opened and closed accordingly. The intake port 180 is provided with an intake leaf valve that is actuated as the piston assembly 110 moves within the cylinder 100. The intake leaf valve is opened and closed by the internal pressure of the cylinder 100.
[0048] An example of an internal combustion engine of the present invention is disclosed herein, but other alternative, modified, usage, and / or equivalent forms thereof are possible. All possible combinations of the embodiments described herein are also included. For example, an appropriate number of cylinders other than four is possible.
[0049] The scope of the present disclosure should not be limited by the specific embodiments disclosed herein, but should be determined only by reading the following claims fairly.
[0050] The reference signs related to the drawings described in parentheses in the claims are only intended to enhance the understanding of the claims and should not be construed as limiting their scope.
Claims
1. at least one cylinder (100) supported by an engine mount (240); a piston assembly (110) slidably received within the cylinder (100) and defining a combustion chamber (200) and a pump chamber (300) axially disposed relative to one another, the piston assembly (110) moving along a first direction within the cylinder (100) to draw a fuel / air / oil mixture into the pump chamber (300), then moving along a second opposite direction to feed the fuel / air / oil mixture into the combustion chamber (200), then moving again along the first direction as the fuel / air / oil mixture is compressed within the combustion chamber (200) by the piston assembly (110), and then moving again along the second direction within the cylinder (100) upon ignition of the compressed fuel / air / oil mixture; an axial flow internal combustion engine (10) comprising: wherein the piston assembly (110) comprises: a piston head (111); a piston body (112); a connecting rod (135) having an end (130) connected to the piston head (111); a cam follower (150) attached to the piston body (112) and directly contacting a surface (410) of a single power cam (400), whereby displacement of the piston assembly (110) within the cylinder (100) rolls the cam follower (150) on the surface (410) of the single power cam (400) to rotate the single power cam (400); an axial flow internal combustion engine (10).
2. The internal combustion engine (10) according to claim 1, wherein the engine mount (240) has an opening (500) for receiving the piston body (112).
3. The internal combustion engine (10) according to claim 1 or claim 2, comprising a plurality of cylinders (100) each having a corresponding piston assembly (110) and a single power cam (400) associated with the piston assembly (110), the pump chamber (300) and the combustion chamber (200) being defined by each piston assembly (110) within each cylinder (100).
4. The internal combustion engine (10) according to any one of the preceding claims, comprising fuel control means (170) for adjusting the amount of fuel and / or air flowing into the cylinder (100).
5. The internal combustion engine according to claim 4, wherein the fuel control means (170) comprises at least one carburetor or fuel injection system.
6. The internal combustion engine (10) according to any one of claims 2 to 5, comprising a common crankcase (160) for the cylinder (100).
7. The internal combustion engine (10) according to claim 6, wherein the fuel control means (170) is arranged within the common crankcase (160).
8. The internal combustion engine (10) according to any one of the preceding claims, wherein the cylinder (100) further comprises at least one intake port (180) for sucking the fuel / air / oil mixture into the pump chamber (300) of the cylinder (100), at least one transfer port (185) for the flow of the fuel / air / oil mixture from the pump chamber (300) of the cylinder (100) to the combustion chamber (200), and at least one exhaust port (190) for exhausting combustion gases from the combustion chamber (200).
9. The internal combustion engine (10) according to claim 8, wherein the exhaust port (190) is arranged to open before the transfer port (185) opens and close after the transfer port (185) closes.
10. The internal combustion engine (10) according to any one of the preceding claims, wherein the cam follower (150) is provided with at least one channel (113) for a lubricant passage.
11. The internal combustion engine (10) according to any one of the preceding claims, wherein the cam follower (150) is arranged to act near the central region of the surface (410) of the single power cam (400).
12. The internal combustion engine (10) according to any one of the preceding claims, comprising a roller bearing (430) for the rotation of the single power cam (400).
13. The internal combustion engine (10) according to any one of the preceding claims, provided with a connecting rod (135) for connecting the piston head (111) to the piston body (112).
14. The internal combustion engine (10) according to any one of the preceding claims, wherein at least one longitudinal guide (115) is provided for guiding the piston body (112) when the piston body (112) of the piston assembly (110) moves within the engine mount (240).
15. The internal combustion engine (10) according to claim 14, wherein a plurality of longitudinal guides (115) are provided for guiding the piston body (112) when the piston body (112) of the piston assembly (110) moves within the engine mount (240), and at least one longitudinal guide (115) located at the outermost part of the engine mount (240) is larger than the other longitudinal guides (115).