Piston motion coupled closed cam engine

Abstract

The application discloses a piston motion coupling closed cam engine, which comprises a box body, N piston assemblies, 2N guide members, a cylindrical cam and a swing rod; the piston assembly comprises a piston body, a piston head and a connecting rod, a roller is installed at the lower end of the piston body, the roller is in rolling contact with the cam surface of the cylindrical cam; the swing rod shaft on the box body is provided with the swing rod, the swing rod can rotate around the swing rod shaft and simultaneously contact with the connecting rod pin shafts in the adjacent two piston assemblies, the reverse symmetrical motion of the adjacent two pistons is coupled to realize the shape closure; the connecting rod pin shaft and the roller pin shaft axis in the piston assembly form a preset included angle to ensure the correct contact between the swing rod and the connecting rod pin shaft; each piston assembly moves along the axis according to the profile of the cam surface and drives the cylindrical cam to rotate under the constraint of the two side guide member moving pairs. The application can improve the output power through the motion coupling of two pistons, eliminate the gap impact, suppress the vibration, improve the dynamic performance, and the structure is easy to process and assemble.

Description

Technical Field

[0001] This invention relates to the field of engines, specifically to the field of engine transmission mechanisms, and particularly to the design of a novel axial cam engine transmission mechanism. Background Technology

[0002] Unmanned aerial vehicles (UAVs) have been widely used in military fields such as border patrol, surveillance and reconnaissance, and air strikes, as well as civilian scenarios such as agriculture, forestry, animal husbandry, aerial photography and mapping, and emergency disaster relief, due to their advantages of high flexibility, strong adaptability to complex environments, and low maintenance costs. Among these applications, the engine, as the "heart" of the UAV, directly affects its overall performance, including payload capacity, endurance, flight speed, and maneuverability. Compared to engines used in ships, vehicles, and other waterborne and ground equipment, UAV engines require a higher power-to-weight ratio to reduce the engine's weight as a percentage of the UAV's takeoff weight; simultaneously, they need to strictly control the frontal area to reduce air resistance and improve overall aerodynamic performance. Therefore, developing new engines with compact structures and high power-to-weight ratios has become a research hotspot in the UAV field. Currently, piston-cam engines, due to their advantages of high thermal efficiency, simple structure, controllable piston motion, and ease of maintenance, are seeing continued research and development in UAV power systems.

[0003] In camshaft engines, the rollers and the cam surface must maintain high-pair contact through form closure. Currently, scholars both domestically and internationally have proposed various existing technical solutions for the form-closure structure design of cam mechanisms in piston engines. Common existing solutions include slotted cam piston engines and roller-clamped cam piston engines. The slotted cam piston engine uses a slotted cam as the core transmission component. The piston achieves the conversion between reciprocating and rotational motion through the contact between the rollers and the two curved surfaces of the slotted cam, thus completing power transmission. The roller-clamped cam piston engine uses multiple rollers clamped onto the cam surface, utilizing the contact between the rollers and the two curved surfaces of the cam to achieve form closure and ensure transmission stability. Both of these solutions achieve power output through the cam mechanism, providing a reference for the form-closure structure design of piston engines.

[0004] However, the aforementioned existing technical solutions have some drawbacks. The double-sided curved surface of the cam needs to maintain high tolerance requirements, which makes machining difficult and increases manufacturing costs; the piston rollers contact the double-sided curved surface simultaneously, making them highly sensitive to assembly errors and difficult to preload, resulting in lateral impacts that affect the engine's power performance. Summary of the Invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, the present invention proposes a small-volume, high-efficiency piston motion coupled closed cam engine.

[0006] To solve the above-mentioned technical problems, the present invention proposes a piston motion coupling closed cam engine, including a housing, N piston assemblies, a cylindrical cam and a rocker arm. The housing includes a main housing, with a cylinder and a cylinder head arranged from bottom to top on the upper end of the main housing, and an end cover provided at the lower end of the main housing. The cylindrical cam is disposed in the lower part of the main housing and has an output shaft to output motion.

[0007] The N sets of piston assemblies are disposed on the upper part of the main housing. Each piston assembly includes a piston body, a piston head, and a connecting rod. One end of the connecting rod is hinged to the piston head, and the other end of the connecting rod is hinged to the upper end of the piston body via a connecting pin. A roller is mounted on the lower end of the piston body via a roller pin. A rocker arm shaft is mounted on the main housing, and a rocker arm is mounted on the rocker arm shaft, allowing the rocker arm to rotate around the rocker arm shaft. The rocker arm simultaneously contacts the connecting rod pins of two adjacent piston assemblies, achieving a closed loop by coupling the opposite symmetrical movements of the two adjacent piston assemblies. The axes of the connecting rod pins and roller pins in the piston assembly form a preset angle, causing the rocker arm shaft to contact the two adjacent roller pins. The axes of the three pins are parallel to each other to ensure line contact between the rocker arm and the connecting rod pin. M guide members, M=2*N, are fixedly installed on the main housing, arranged with one guide member on each side of each piston assembly. Each piston assembly forms a sliding pair with the guide members on both sides. The bottom end of each guide member has a cam groove, and the top of the working end of the cylindrical cam is a cam surface. The working end of the cylindrical cam is embedded in the cam groove, which prevents interference between the guide member and the cam surface. The rocker arm applies axial preload to all piston assemblies, and the rollers in all piston assemblies roll in contact with the cam surface of the cylindrical cam.

[0008] Under the constraint of the housing, the piston assembly reciprocates along the axis according to the profile of the cam surface of the cylindrical cam, and drives the cylindrical cam to rotate.

[0009] Furthermore, in the piston motion coupled closed cam engine of the present invention:

[0010] The guide member is provided with a rocker arm groove, and the rocker arm passes through the rocker arm groove. The rocker arm groove is used to prevent the guide member from interfering with the rocker arm.

[0011] The bottom end of the guide member is provided with a connecting boss, and the connecting boss is provided with a bolt through hole, so that the guide member is fixedly connected to the main box body by bolts.

[0012] In this invention, by adjusting the preload applied to the relative position of the rocker arm and the cylindrical cam along the axial direction, the gaps between the piston assembly and the cylindrical cam, and between the piston assembly and the rocker arm, are eliminated, thereby suppressing impact.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] The piston motion-coupled closed cam engine of this invention utilizes a rocker arm to couple adjacent pistons to achieve a closed shape, effectively taking advantage of the periodic symmetrical cyclic motion characteristics of two adjacent sets of pistons. Therefore, during the compression phase, the piston inertial force can be transmitted to the power piston through the rocker arm, thereby driving the cam to rotate and increasing output power. Simultaneously, because the two adjacent pistons are kinematically coupled through the rocker arm, their dynamic responses can be mutually suppressed through phase tuning, inhibiting system vibration and improving system dynamic performance. Furthermore, compared to existing slotted cam and roller-clamped cam piston engines, where the piston rollers and cam's two curved surfaces simultaneously contact each other, this invention is simpler to manufacture and assemble, facilitates pre-tightening of the cam rollers, effectively eliminates clearance impact, and improves power performance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the internal structure of the piston motion coupled closed cam engine of the present invention.

[0016] Figure 2 This is a cross-sectional structural schematic diagram of the engine described in this invention;

[0017] Figure 3 This is a partial cross-sectional view of the housing in the engine described in this invention;

[0018] Figure 4 This is a schematic diagram showing the connection relationship between the rocker arm, guide member, and piston assembly in the engine described in this invention;

[0019] Figure 5 This is a schematic diagram showing the connection relationship between the piston assembly and the guide member in the engine described in this invention;

[0020] Figure 6 This is a schematic diagram of the structure between the guide member and the housing in the engine described in this invention;

[0021] Figure 7 This is a partial cross-sectional view of the connection relationship between the rocker arm and the piston assembly in the engine described in this invention.

[0022] In the diagram: 10-Piston assembly, 11-Piston head, 12-Connecting rod, 13-Connecting rod pin, 14-Piston body, 15-Roller pin, 16-Roller, 20-Cylindrical cam, 21-Cam surface, 22-Output shaft, 30-Rocker, 31-Rocker shaft, 40-Box housing, 41-Cylinder head, 42-Cylinder, 43-Main box housing, 431-Groove, 44-End cap, 45-Guide component, 451-Connecting boss, 452-Cam groove, 453-Rocker groove. Detailed Implementation

[0023] This invention proposes a piston motion-coupled closed cam engine, comprising a piston assembly, a cylindrical cam, a rocker arm, and a housing. The design concept is as follows: the piston assembly reciprocates along its axis under the constraint of the housing; the rollers of the piston assembly contact the cylindrical cam, driving the cam to rotate. Simultaneously, the rocker arm contacts the connecting rod pins of two adjacent piston assemblies, achieving closed-loop operation through coupling the opposite symmetrical movements of the two adjacent piston assemblies. To ensure proper contact between the rocker arm and the connecting rod pins, the axis of the connecting rod pin and the axis of the roller pin form a predetermined angle. This invention can improve output power, eliminate gap impact, suppress vibration, and improve dynamic performance through the motion coupling of the two pistons, and its structure is easy to manufacture and assemble.

[0024] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. The features and objectives of the present invention will become more apparent. It is understood that the specific embodiments described herein are only for explaining the relevant invention and not for limiting the invention. It should be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings. Furthermore, it should be emphasized that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0025] The present invention proposes a four-piston piston motion coupled closed cam engine, including a housing 40, four piston assemblies 10, a cylindrical cam 20 and a rocker arm 30.

[0026] like Figure 1 and Figure 2 As shown, the housing 40 includes a main housing 43. A cylinder 42 and a cylinder head 41 are arranged from bottom to top on the upper end of the main housing 43. An end cap 44 is provided at the lower end of the main housing 43 to facilitate assembly and adjustment. Figure 2 As shown, the cylindrical cam 20 is disposed at the lower part of the main housing 43, and the cylindrical cam 20 is provided with an output shaft 22 to output motion.

[0027] The four piston assemblies 10 are located on the upper part of the main housing 43 and are evenly distributed circumferentially on one side of the cylindrical cam 20, thereby making the engine structure more compact. Figure 1 and Figure 5 As shown, the piston assembly 10 includes a piston body 14, a piston head 11, a connecting rod 12, a connecting rod pin 13, a roller pin 15, and a roller 16. One end of the connecting rod 12 is hinged to the piston head 11, and the other end of the connecting rod 12 is hinged to the upper end of the piston body 14 via the connecting pin 13. The lower end of the piston body 14 is fitted with the roller 16 via the roller pin 15. Figure 1 and Figure 3As shown, a swing arm shaft 31 is mounted on the main housing 43, and a swing arm 30 is mounted on the swing arm shaft 31, allowing the swing arm 30 to rotate around the swing arm shaft 31. Figure 1 , Figure 3 , Figure 4 As shown, the roller 16 contacts the cam surface 21 on the cylindrical cam 20; the piston assembly 10, constrained by the housing 40, reciprocates along the axis and contacts the cylindrical cam 20 through the bottom roller 16, driving the cylindrical cam 20 to rotate. Figure 3 and Figure 7 As shown, the rocker arm 30 simultaneously contacts the connecting rod pins 13 in two adjacent piston assemblies 10, achieving a closed mechanism by coupling the opposite symmetrical movements of the two adjacent piston assemblies 10. The connecting rod pins 13 and roller pins 15 in the piston assembly 10 form a preset angle. In this embodiment, for example... Figure 3 and Figure 7 As shown, the rocker arm 30 is hinged to the housing 40 via the rocker arm shaft 31, forming a rotating pair; the two ends of the rocker arm 30 are respectively in contact with the connecting rod pins 13 of the two adjacent piston assemblies 10; to ensure that the rocker arm 30 and the connecting rod pins 13 achieve line contact in the embodiment, the rocker arm shaft 31 and the roller pins 15 in the two adjacent piston assemblies 10 are all at a 45° angle, and at the same time, the axes of each connecting rod pin 13 and the corresponding roller pin 15 are at a 45° angle to each other, so that the axes of the rocker arm shaft 31 and the two adjacent roller pins 15 are parallel to each other.

[0028] like Figures 3 to 5 As shown, eight guide members 45 are fixedly installed on the main housing 43, arranged such that one guide member 45 is provided on each side of each piston assembly 10, and each piston assembly 10 forms a sliding pair with the guide members 45 on both sides. The axial length of the guide member 45 should completely cover the entire stroke of the piston body 14 reciprocating motion to avoid the piston body 14 from being cantilevered due to insufficient effective engagement length of the sliding pair, thereby avoiding the deterioration of the stress condition of the piston assembly 10.

[0029] like Figure 5 and Figure 6 As shown, the bottom end of the guide member 45 is provided with a connecting boss 451 and a cam groove 452. The connecting boss 451 is provided with a bolt through hole. The guide member 45 is fixed to the main housing 43 by bolts, which is used to realize the bolt connection positioning between the guide member 45 and the housing 40.

[0030] like Figure 4 and Figure 5As shown. The top of the working end of the cylindrical cam 20 is a cam surface 21, and the working end of the cylindrical cam 20 is embedded in the cam groove 452. The cam groove 452 is used to prevent the guide member 45 from interfering with the cam surface 21. The guide member 45 is provided with a rocker arm groove 453, and the rocker arm 30 passes through the rocker arm groove 453. The rocker arm groove 453 is used to prevent the guide member 45 from interfering with the rocker arm 30. Figure 6 As shown, the main housing 43 is provided with a groove 431 to avoid interference between the main housing 43 and the cam surface 21.

[0031] In the piston motion-coupled closed cam engine of the present invention, the rocker arm 30 applies axial preload to all piston assemblies 10, and the rollers 16 in all piston assemblies 10 are in rolling contact with the cam surface 21 of the cylindrical cam 20; as Figure 1 and Figure 2 As shown, the piston assembly 10, constrained by the housing 40, reciprocates along the axis according to the profile of the cam surface 21 of the cylindrical cam 20, and drives the cylindrical cam 20 to rotate.

[0032] The piston motion-coupled closed cam engine of the present invention can effectively eliminate the gaps between the piston assembly 10 and the cylindrical cam 20, and between the piston assembly 10 and the rocker arm 30, by adjusting the preload applied along the axial relative position between the rocker arm 30 and the cylindrical cam 20, thus suppressing impact. Simultaneously, by setting the rocker arm 30, the periodic symmetrical cyclic motion characteristics of the two adjacent sets of pistons 10 are effectively utilized. During the compression phase, the inertial force of the compression piston 10 can be transmitted to the power piston 10 through the rocker arm 30, thereby driving the cam 20 to rotate and increasing output power. Furthermore, the dynamic responses of the two adjacent pistons 10 can be mutually suppressed through phase tuning, suppressing system vibration and improving system dynamic performance. Compared with existing slotted cam piston engines and roller-clamped cam piston engines, the piston motion-coupled closed cam engine of the present invention is simple to manufacture and assemble, easily achieves preload on the cam rollers, effectively eliminates gap impact, and improves power performance.

[0033] The above description is merely a preferred embodiment of the technical solution of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the concept of the present invention. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention are all within the protection scope of this invention.

Claims

1. A piston motion coupled closed cam engine, comprising a housing (40), N piston assemblies (10), a cylindrical cam (20), and a rocker arm (30), characterized in that: The housing (40) includes a main housing (43), and a cylinder (42) and a cylinder head (41) are arranged from bottom to top on the upper end of the main housing (43), and an end cap (44) is provided on the lower end of the main housing (43). The cylindrical cam (20) is located at the lower part of the main housing (43), and the cylindrical cam (20) is provided with an output shaft (22) to output motion; The N sets of piston assemblies (10) are disposed on the upper part of the main housing (43). The piston assembly (10) includes a piston body (14), a piston head (11) and a connecting rod (12). One end of the connecting rod (12) is hinged to the piston head (11), and the other end of the connecting rod (12) is hinged to the upper end of the piston body (14) through a connecting pin (13). The lower end of the piston body (14) is equipped with a roller (16) through a roller pin (15). The main housing (43) is equipped with a rocker arm shaft (31), and the rocker arm (30) is mounted on the rocker arm shaft (31). The rocker arm (30) can rotate around the rocker arm shaft (31). The rocker arm (30) is in contact with the connecting rod pins (13) in the two adjacent piston assemblies (10) at the same time. The rocker arm (30) achieves a closed shape by coupling the opposite symmetrical movements of the two adjacent piston assemblies (10). The axes of the connecting rod pins (13) and the roller pins (15) in the piston assembly (10) are at a preset angle, so that the axes of the rocker arm shaft (31) and the two adjacent roller pins (15) are parallel to each other, so as to ensure that the rocker arm (30) and the connecting rod pins (13) achieve line contact. M guide members (45) are fixedly installed on the main housing (43), M=2*N, and are arranged such that one guide member (45) is set on each side of each piston assembly (10), and each piston assembly (10) and the guide members (45) on both sides form a sliding pair; The bottom end of the guide member (45) is provided with a cam groove (452), and the top of the working end of the cylindrical cam (20) is a cam surface (21). The working end of the cylindrical cam (20) is embedded in the cam groove (452). The cam groove (452) is used to avoid interference between the guide member (45) and the cam surface (21). The rocker arm (30) applies axial preload to all piston assemblies (10), and the rollers (16) in all piston assemblies (10) are in rolling contact with the cam surface (21) of the cylindrical cam (20). The piston assembly (10), constrained by the housing (40), reciprocates along the axis according to the profile of the cam surface (21) of the cylindrical cam (20) and drives the cylindrical cam (20) to rotate.

2. The piston motion coupled closed cam engine according to claim 1, characterized in that, The guide member (45) is provided with a rocker arm groove (453), and the rocker arm (30) passes through the rocker arm groove (453). The rocker arm groove (453) is used to avoid interference between the guide member (45) and the rocker arm (30).

3. The piston motion coupled closed cam engine according to claim 1, characterized in that, The bottom end of the guide member (45) is provided with a connecting boss (451), and the connecting boss (451) is provided with a bolt through hole, and the guide member (45) is fixedly connected to the main box (43) by bolts.

4. The piston motion coupled closed cam engine according to claim 1, characterized in that, By adjusting the preload applied between the rocker arm (30) and the cylindrical cam (20) along the axial direction, the gaps between the piston assembly (10) and the cylindrical cam (20) and between the piston assembly (10) and the rocker arm (30) are eliminated, thus suppressing the impact.

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