Crankshaft-free bevel gear connecting rod transmission mechanism for two-stroke piston engine

Abstract

The invention discloses a crankshaft-free bevel gear connecting rod transmission mechanism for a two-stroke piston type engine, and belongs to the field of two-stroke piston type engines. A piston is improved, a guide groove is designed in the inner wall of a cavity of a piston skirt portion, and the molded line of the guide groove is a curve of reciprocating motion displacement of the piston along with time change. One end of each bevel gear transmission rod is provided with a double-ball piston pin, the double-ball piston pins are installed in the guide grooves in a sliding mode, the other end of each bevel gear transmission rod is provided with an input bevel gear meshed with an output bevel gear, two pistons provided with the bevel gear transmission rods are symmetrically arranged on the two sides of the output bevel gear, and the output bevel gear is coaxially provided with an output shaft; the output shaft is used for outputting the torque to an external load device. The transmission mechanism is different from a traditional crank connecting rod mechanism, the structural complexity caused by forced lubrication of the small end of the connecting rod in the traditional crank connecting rod mechanism can be avoided, the weight of an engine can be reduced, and the power-to-weight ratio of the engine can be increased.

Description

Technical Field

[0001] The present invention relates to the field of two-stroke piston engines, and in particular to a crankshaft-free bevel gear connecting rod transmission mechanism for a two-stroke piston engine. Background Art

[0002] Traditional piston engines use a crank-connecting rod mechanism to transmit power. The crank-connecting rod mechanism converts the force of the gas acting on the top of the piston into the torque of the crankshaft to output mechanical energy to the working machine.

[0003] In the crank-connecting rod mechanism of a traditional piston engine, the connecting rod must both reciprocate with the piston and rotate with the crankshaft, enduring alternating loads such as compression, tension, and bending. Under high-load and high-temperature conditions, the small end of the connecting rod requires additional forced lubrication to avoid dry friction and prevent piston pin seizure.

[0004] In a traditional piston engine, the crankshaft is subjected to a combination of centrifugal force from the rotating mass, cyclically varying gas pressure, and reciprocating inertia, resulting in bending and torsional loads. To balance the engine's unbalanced centrifugal force, centrifugal torque, and some reciprocating inertia, the crankshaft typically requires counterweights to prevent severe engine vibration. The crankshaft typically accounts for 8%-20% of the total engine weight, but to ensure adequate strength and rigidity, excessive weight reduction is essential.

[0005] Therefore, it is worthwhile to study how to design a new transmission structure to avoid the existing crank-connecting rod transmission method. Summary of the Invention

[0006] Technical issues to be solved: In order to avoid the shortcomings of the prior art, the present invention provides a crankshaft-less bevel gear connecting rod transmission mechanism for a two-stroke piston engine. By improving the piston, a guide groove is designed on the inner wall of the piston skirt, a double-ball head piston pin is provided at one end of the bevel gear transmission rod, and the double-ball head piston pin is slidably installed in the guide groove. An input bevel gear is provided at the other end of the bevel gear transmission rod to mesh with an output bevel gear. Two pistons equipped with bevel gear transmission rods are symmetrically arranged on both sides of the output bevel gear, thereby providing a non-traditional crankshaft connecting rod transmission mechanism, which can reduce the weight of the two-stroke piston engine and avoid the structural complexity caused by adding forced lubrication to the small end of the connecting rod.

[0007] The technical solution of the present invention is: a crankshaft-less bevel gear connecting rod transmission mechanism for a two-stroke piston engine, comprising: Two pistons are coaxially arranged opposite each other and are respectively installed in their corresponding engine cylinders. The pistons include a coaxially arranged head and skirt. The piston head is slidably placed in the engine cylinder. The two skirts have cavities formed on opposite end surfaces. The inner walls of the cavities have guide grooves. The profile of the guide grooves is a curve representing the displacement of the piston in reciprocating motion over time. Two bevel gear transmission rods are coaxially mounted corresponding to the two pistons. One end of the bevel gear transmission rod is provided with an input bevel gear, and the other end thereof extends into the cavity of the skirt, and the end portion extending into the cavity is slidably connected to the guide groove. A transmission assembly, one end of which is synchronously connected to the input bevel gears of the two bevel gear transmission rods, and the other end is used for transmission connection with the load device; Among them, during the power stroke of the engine, when the two pistons in their respective engine cylinders are thrust by the work of the combustion gas and move toward the transmission assembly at the same time, the pistons push the bevel gear transmission rod to rotate along the guide groove, and the input bevel gear drives the transmission assembly to rotate, thereby outputting the torque; during the intake, compression and exhaust strokes of the engine, the inertial rotation of the transmission assembly drives the bevel gear transmission rod to rotate, and the bevel gear transmission rod rotates along the guide groove to push the piston to reset.

[0008] A further technical solution of the present invention is: a double-ball piston pin is provided at one end of the bevel gear transmission rod extending into the cavity, and the ball heads at both ends of the double-ball piston pin are slidably connected to the guide groove; the groove cross-section of the guide groove is adapted to the ball heads of the double-ball piston pin.

[0009] A further technical solution of the present invention is: the rod body of the bevel gear transmission rod is an I-section structure with a gradually changing cross-section, one end of the rod body is coaxially fixed with the input bevel gear, and the other end is fixed with a double-ball piston pin, and the axis of the double-ball piston pin intersects the axis of the bevel gear transmission rod perpendicularly.

[0010] A further technical solution of the present invention is that the transmission assembly includes an output shaft, one end of the output shaft is coaxially provided with an output bevel gear, the output bevel gear is engaged with the two input bevel gears at the same time, and the other end of the output shaft is used to connect to the load device.

[0011] A further technical solution of the present invention is that the axis of the output shaft and the axis of the bevel gear transmission rod form an angle of 90°.

[0012] A further technical solution of the present invention is: the outer diameter wall of the skirt of the piston is evenly distributed with multiple concave pin grooves, and the groove direction of the pin grooves is the same as the axial direction of the piston; a positioning pin is slidably installed in each pin groove, one end of the positioning pin is fixed to the inner wall of the engine cylinder body, and the other end is embedded in the pin groove; the positioning pin is used to prevent the piston from rotating in the engine cylinder body.

[0013] A further technical solution of the present invention is that the axial length of the pin groove meets the stroke requirement of the reciprocating motion of the piston.

[0014] A further technical solution of the present invention is that: a plurality of transmission assemblies are provided, and the plurality of transmission assemblies are used to correspond to a plurality of external load devices.

[0015] A further technical solution of the present invention is that a ring groove is provided at one end of the piston head away from the skirt, the ring groove is used to install a piston ring, and the piston ring is used to seal between the piston and the inner wall of the engine cylinder.

[0016] The beneficial effects of the present invention are as follows: a crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine is provided. By improving the piston, a guide groove is provided on the inner surface of the piston skirt cavity, so that the double-ball piston pin of the bevel gear transmission rod is slidably connected to the guide groove, and the input bevel gear of the bevel gear transmission rod meshes with the output bevel gear. When the two pistons are subjected to the thrust of the combustion gas in the engine cylinder and move toward the transmission assembly, the guide groove wall in the piston pushes the double-ball piston pin to rotate, thereby driving the bevel gear transmission rod to rotate. The bevel gear transmission rod drives the output bevel gear to rotate, and the output shaft outputs the torque to an external load device. The present invention replaces the crank-connecting rod mechanism in a traditional piston engine with the guide groove on the inner surface of the piston skirt cavity, the bevel gear transmission rod, and the transmission assembly, simplifying the transmission mechanism of the two-stroke piston engine and achieving a lightweight design.

[0017] The structure of the present invention replaces the crank in a traditional piston engine with a guide groove on the inner surface of the piston skirt cavity. The profile of the guide groove is a curve showing the change of the piston's reciprocating displacement over time. The piston's stroke, movement direction, speed and acceleration are controlled by the profile of the guide groove.

[0018] The present invention replaces the connecting rod in a traditional piston engine with a bevel gear transmission rod. The traditional connecting rod not only reciprocates with the piston but also rotates with the crankshaft, while the bevel gear transmission rod only rotates, avoiding bearing multiple loads and increasing service life.

[0019] The structure of the present invention replaces the crankshaft in a traditional piston engine with a transmission assembly. The transmission assembly adopts a gear shaft structure, including an output bevel gear and an output shaft. Its structure is simple and torque can be directly output to an external load device through its output shaft, which is conducive to the lightweight design of the engine and improves the power-to-weight ratio of the engine.

[0020] In the present invention, the two pistons are symmetrically arranged with the axis of the output bevel gear as the symmetry axis. According to the transmission characteristics of the bevel gear, when the piston on one side moves downward, the piston on the other side will move downward at the same time. When the piston on one side moves upward, the piston on the other side will move upward at the same time, thereby achieving self-balancing of the reciprocating inertial force, helping to reduce vibration and noise, and improving the overall durability of the engine.

[0021] The meshing bevel gears in this invention can directly transmit power and motion between intersecting axes. Therefore, while ensuring a 90° angle between the output bevel gear and the axis of the bevel gear transmission rod (that is, a 90° angle between the output shaft and the axis of the bevel gear transmission rod), the output shaft's axis can be freely adjusted within a plane perpendicular to the axis of the bevel gear transmission rod, increasing the flexibility of the engine's power output direction. Furthermore, the number of output bevel gears can be more than one. As long as there is no contact interference between the multiple output bevel gears, the engine can be equipped with multiple output bevel gears and corresponding output shafts to simultaneously drive multiple load devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is an exploded view of the overall structure of a crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to the present invention; Figure 2 Schematic diagram of the assembly of a crankshaft-less bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to the present invention; Figure 3 Schematic diagram of the piston structure in the present invention; Figure 4 It is the curve of piston displacement changing with time, that is, the linear curve graph of the guide groove.

[0024] In the figure: 1. Piston, 11. Head, 12. Skirt, 13. Guide groove, 14. Pin groove, 15. Ring groove, 2. Bevel gear transmission rod, 21. Double-ball piston pin, 22. Input bevel gear, 23. Rod body, 3. Transmission assembly, 31. Output bevel gear, 32. Output shaft, 4. Dowel pin. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] An embodiment of a crankshaft-less bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to the present invention is as follows: Figure 1 As shown, it includes two pistons 1, two bevel gear transmission rods 2 and a transmission assembly 3.

[0027] Also see 2. Figure 3 The two pistons 1 are coaxial and symmetrically arranged on either side of the central axis of the transmission assembly 3. The two pistons 1 are mounted within the cylinders of their respective two-stroke piston engines and reciprocate along their respective cylinder axes. The pistons 1 are cylindrical in structure, comprising a coaxial head 11 and a skirt 12. The outer diameter of the head 11 is larger than that of the skirt 12. An annular groove 15 is provided on the edge of the head 11 facing away from the skirt 12. This groove 15 is used to receive piston rings, which seal between the piston head 11 and the inner wall of the engine cylinder. The opposing end faces of the two piston skirts 12 have concave cavities. These cavities are cylindrical structures extending along the axial direction of the pistons 1. The inner walls of these cavities are provided with guide grooves 13, which provide a sliding connection with the bevel gear transmission rod 2. To reduce the weight of the pistons 1, the cavity within the skirt 12 extends inward to the head 11 of the piston 1. While ensuring the wall strength of the piston 1, the diameter of the cavity at the head 11 is larger than that at the skirt 12, forming a cylindrical stepped cavity. The outer end of the head 11 away from the skirt 12 is the closed end of the piston 1, and the outer end of the skirt 12 away from the head 11 is the open end of the cavity. When the two pistons 1 are installed, the open ends face each other.

[0028] The two bevel gear transmission rods 2 correspond to the two pistons 1 one by one and are coaxially installed. Figure 1 As shown, the bevel gear transmission rod 2 includes an input bevel gear 22, a rod body 23, and a double-ball piston pin 21. The rod body 23 serves as the main support portion of the bevel gear transmission rod 2. In order to reduce its weight and ensure sufficient support strength and rigidity, the rod body 23 has an I-shaped cross-section structure with a tapered cross-section. The cross-sectional dimension of one end is smaller than that of the other end, forming an isosceles triangle structure. The small-sized end of the rod body 23 is coaxially fixedly mounted with the input bevel gear 22, and the other end of the rod body 23 is fixed with a double-ball piston pin 21. The tooth surface of the input bevel gear 22 faces away from the double-ball piston pin 21. The double-ball piston pin 21 is a cylindrical pin with ball heads at both ends. The axis of the double-ball piston pin 21 is perpendicular to the axis of the bevel gear transmission rod 2, that is, perpendicular to the axis of the input bevel gear 22. The double-ball piston pin 21 is embedded in the cavity of the skirt 12, and the ball heads at both ends are slidably connected to the guide grooves 13. The input bevel gear 22 is exposed at the open end of the piston skirt 12 for cooperation with the power output bevel gear shaft 3.

[0029] In this embodiment, the transmission assembly 3 is provided with a gear shaft, which includes an output bevel gear 31 and an output shaft 32. The output shaft 32 is coaxially fixed to the back of the teeth of the output bevel gear 31. The output bevel gear 31 is located between the two bevel gear transmission rods 2 and is simultaneously meshed with the two input bevel gears 22. The end of the output shaft 32 away from the output bevel gear 31 is connected to the external load device. The axis of the output bevel gear 31 (also the axis of the output shaft 32) and the axis of the bevel gear transmission rod 2 have an axial intersection angle of 90°. Therefore, the two pistons 1 and the two bevel gear transmission rods 2 are symmetrical with respect to the axis of the output shaft 32. Under the premise of ensuring that the axis of the output bevel gear 31 and the axis of the bevel gear transmission rod 2 have an axial intersection angle of 90°, the direction of the central axis of the output bevel gear 31 can be freely adjusted, that is, the direction of the engine power output can be flexibly adjusted.

[0030] In other embodiments, multiple transmission assemblies 3 may be provided as needed, with multiple transmission assemblies 3 being used to connect to multiple external load devices, thereby satisfying the need for the engine to simultaneously drive multiple loads. When multiple transmission assemblies 3 are installed, the axis of each output bevel gear 31 is perpendicular to the axis of the bevel gear transmission rod 2, and each output bevel gear 31 simultaneously meshes with two input bevel gears 22, ensuring that the multiple output bevel gears 31 do not interfere with each other.

[0031] See Figure 3 、 Figure 4 The profile of the guide groove 13 is a curve showing the reciprocating displacement of the piston 1 changing with time. The guide groove 13 determines the reciprocating stroke, direction, speed and acceleration of the piston 1. The cross-section of the guide groove 13 is adapted to the ball head of the double-ball piston pin 21 so that it can slide in the guide groove 13.

[0032] Piston 1 reciprocates within the engine cylinder in which it is installed. To prevent piston 1 from rotating relative to the cylinder, two inwardly concave pin slots 14 are evenly distributed on the outer diameter wall of piston skirt 12. Pin slots 14 align with the axial direction of piston 1. A locating pin 4 is slidably mounted within each pin slot 14. This locating pin 4 is a ball-end locating pin, one end of which is fixed to the inner wall of the engine cylinder and the other end slides into pin slot 14. The axial length of pin slot 14 along the axis of piston 1 satisfies the stroke requirements of piston 1's reciprocating motion. While locating pin 4 remains stationary, piston 1 reciprocates linearly. Each piston 1 is prevented from rotating within the engine cylinder by two locating pins 4, restricting piston 1 to reciprocating linear motion along its axis.

[0033] It should be noted that the input bevel gear 22 of the two bevel gear transmission rods 2 and the output bevel gear 31 of the transmission assembly 3 in this embodiment are installed in the gear box through their respective support bearings, so as to realize the positioning of the bevel gear transmission rod 2 and the transmission assembly 3, and prevent the two bevel gear transmission rods 2 and the transmission assembly 3 from moving along their respective axial directions.

[0034] Working principle: It is stipulated that the piston 1 makes a linear motion along its axis toward the transmission assembly 3, which is called the piston 1 downward movement; the piston 1 makes a linear motion along its axis toward a direction away from the transmission assembly 3, which is called the piston 1 upward movement.

[0035] During the engine's power stroke, the combustible mixture in the engine burns, expands, and converts chemical energy into mechanical energy. Due to gas pressure, both pistons 1 descend simultaneously. As piston 1 descends, the walls of the guide groove 13 on the inner wall of its skirt 12 push the double-ball piston pin 21 to rotate, in turn driving the bevel gear transmission rod 2. The input bevel gear 22 of the bevel gear transmission rod 2 and the output bevel gear 31 of the transmission assembly 3 are always in meshing engagement. The bevel gear transmission rod 2 does not move linearly with piston 1, but rotates only about its axis. Therefore, as piston 1 descends, the double-ball piston pin 21 of the bevel gear transmission rod 2 experiences a circumferential tangential force from the walls of the guide groove 13, pushing the bevel gear transmission rod 2 to rotate about its axis. The two driving bevel gear transmission rods 2 rotate in opposite directions. The input bevel gears 22 of both bevel gear transmission rods 2 simultaneously mesh with the output bevel gear 31 of the transmission assembly 3, driving the output bevel gear 31 to rotate about its axis. The output shaft 32 then transmits torque to the load device.

[0036] During the intake, compression and exhaust strokes of the engine: the transmission assembly 3 relies on inertia to maintain rotation, and the output bevel gear 31 drives the two bevel gear transmission rods 2 to rotate through gear meshing. The double-ball piston pins 21 of the two bevel gear transmission rods 2 generate a circumferential tangential force on the wall of the guide groove 13 on the inner wall of the piston skirt during the rotation process, thereby pushing the piston 1 upward until the piston 1 returns to its original position and enters the next power stroke.

[0037] According to the bevel gear transmission characteristics, when one piston moves downward, the other piston will move downward at the same time, and when one piston moves upward, the other piston will move upward at the same time, and the two bevel gear transmission rods 2 will rotate in opposite directions. This can achieve self-balancing of the reciprocating inertial force, thereby reducing vibration and noise and improving the overall durability of the engine.

[0038] The present invention replaces the crank-connecting rod mechanism in a traditional piston engine with the guide groove 13 on the inner surface of the piston skirt, the bevel gear transmission rod 2 and the transmission assembly 3, thereby simplifying the transmission mechanism and improving the power-to-weight ratio of the engine.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine, characterized in that: include: Two pistons (1) are coaxially arranged opposite to each other and are respectively installed in corresponding engine cylinders; the piston (1) comprises a coaxially arranged head (11) and a skirt (12); the piston head (11) is slidably placed in the engine cylinder; cavities are provided on opposite end surfaces of the two skirts (12); guide grooves (13) are provided on inner walls of the cavities; and the profile of the guide grooves (13) is a curve representing the change in displacement of the reciprocating motion of the piston (1) over time; Two bevel gear transmission rods (2) are arranged in one-to-one correspondence with the two pistons (1) and are coaxially mounted; one end of the bevel gear transmission rod (2) is provided with an input bevel gear (22), and the other end thereof extends into the cavity of the skirt (12), and the end portion extending into the cavity is slidably connected to the guide groove (13); A transmission assembly (3), one end of which is synchronously connected to the input bevel gears (22) of the two bevel gear transmission rods (2), and the other end of which is connected to the load device; In the power stroke of the engine, when the two pistons (1) are subjected to the thrust of the gas power in their respective engine cylinders and move toward the transmission assembly (3) at the same time, the pistons (1) push the bevel gear transmission rod (2) to rotate along the guide groove (13), and the input bevel gear (22) drives the transmission assembly (3) to rotate, thereby outputting the torque; in the intake, compression and exhaust strokes of the engine, the inertial rotation of the transmission assembly (3) drives the bevel gear transmission rod (2) to rotate, and the bevel gear transmission rod (2) rotates along the guide groove (13), thereby pushing the pistons (1) to reset.

2. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 1, characterized in that: One end of the bevel gear transmission rod (2) extending into the cavity is provided with a double-ball piston pin (21), and the ball heads at both ends of the double-ball piston pin (21) are slidably connected to the guide groove (13); the groove cross-section of the guide groove (13) is adapted to the ball heads of the double-ball piston pin (21).

3. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 2, characterized in that: The rod body (23) of the bevel gear transmission rod (2) is an I-shaped cross-section structure with a gradually changing cross-section. One end of the rod body (23) is coaxially fixedly mounted with the input bevel gear (22), and the other end is fixed with a double-ball piston pin (21). The axis of the double-ball piston pin (21) is perpendicularly intersected with the axis of the bevel gear transmission rod (2).

4. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 1, characterized in that: The transmission assembly (3) comprises an output shaft (32), one end of the output shaft (32) is coaxially provided with an output bevel gear (31), the output bevel gear (31) is simultaneously meshed with the two input bevel gears (22), and the other end of the output shaft (32) is used for connecting to a load device.

5. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 4, characterized in that: The axis of the output shaft (32) and the axis of the bevel gear transmission rod (2) form an angle of 90°.

6. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 1, characterized in that: The outer diameter wall of the skirt portion (12) of the piston (1) is uniformly distributed with a plurality of inwardly concave pin grooves (14), the groove direction of the pin grooves (14) being the same as the axial direction of the piston (1); a positioning pin (4) is slidably installed in each pin groove (14), one end of the positioning pin (4) is fixed to the inner wall of the cylinder body of the engine, and the other end is embedded in the pin groove (14); the positioning pin (4) is used to prevent the piston (1) from rotating in the cylinder body of the engine.

7. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 6, characterized in that: The axial length of the pin groove (14) meets the stroke requirement of the reciprocating motion of the piston (1).

8. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 1, characterized in that: The transmission components (3) are provided in plurality, and the plurality of transmission components (3) are used to correspond to a plurality of external load devices.

9. The crankshaftless bevel gear connecting rod transmission mechanism for a two-stroke piston engine according to claim 1, characterized in that: An annular groove (15) is provided at one end of the head (11) of the piston (1) away from the skirt (12). The annular groove (15) is used to install a piston ring, and the piston ring is used to seal between the piston (1) and the inner wall of the engine cylinder.

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