An eccentric crank connecting rod structure

Abstract

The present invention discloses an eccentric crank-connecting rod structure, which is mounted on a cylinder block and includes a crankshaft, a connecting rod, a piston pin, and a piston. The crankshaft is mounted on the cylinder block, and the connecting rod is connected to the crankshaft and the piston pin at opposite ends. The piston is connected to the connecting rod via the piston pin. The piston has a primary thrust side and a secondary thrust side on opposite sides of the piston, and the rotation centerline of the crankshaft is offset by (1.5-3)λmm toward the primary thrust side, where λ = r / ι, r is the radius of the crankshaft, and ι is the length of the connecting rod. The present invention provides an eccentric crank-connecting rod structure that, under conditions of a defined cylinder diameter and connecting rod ratio, adopts an eccentric arrangement, i.e., the crankshaft's rotation center is offset from the cylinder bore center, to reduce piston lateral force, thereby reducing overall friction loss and improving wear life.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to an eccentric crank-connecting rod structure. Background Art

[0002] The existing crankshaft-connecting rod system layout of the Yuchai 3L engine, drawing on design experience from similar light-duty diesel engines of the same displacement, features a crank radius r = 53.45mm, a connecting rod length ι = 159mm, and a connecting rod ratio λ = 2.975. Within the constraints of cylinder diameter and connecting rod ratio, as the maximum explosion pressure of the China VI engine increases, the piston's lateral explosion pressure increases, severely impacting the overall engine's friction losses and wear life.

[0003] Existing patent documents, the patent name is "Internal combustion engine with partial piston offset", the patent number is CN2017113433584, and the publication number is CN108204277A. This invention patent relates to an internal combustion engine with partial piston offset. A reciprocating internal combustion engine having a row of cylinders arranged in parallel, wherein the cylinders are connected by a connecting rod and a piston by means of a crank-connecting rod mechanism that is jointly supported in a crankshaft bearing, wherein the crankshaft bearing of the crank-connecting rod mechanism can have a misalignment relative to the cylinder axis. In this invention patent, the offset scale can be 10-12 mm. However, in the narrow space of the internal combustion engine, such a large offset distance is bound to increase the cost and make the operation difficult. Summary of the Invention

[0004] In response to the above problems, the present invention provides an eccentric crank-connecting rod structure. Under the conditions of limited cylinder diameter and connecting rod ratio, an eccentric arrangement is adopted, that is, the crankshaft rotation center is offset to reduce the lateral force of the piston, thereby reducing the friction loss of the whole machine and improving the wear life. It is simple to operate and reduces costs.

[0005] The present invention adopts the following technical solutions to achieve the above purpose:

[0006] An eccentric crank-connecting rod structure is installed on a cylinder block and includes a crankshaft, a connecting rod, a piston pin and a piston. The crankshaft is installed on the cylinder block, and the opposite ends of the connecting rod are respectively connected to the crankshaft and the piston pin. The piston is connected to the connecting rod via the piston pin. The opposite sides of the piston are respectively provided with a main thrust side and a secondary thrust side. The rotation centerline of the crankshaft is offset toward the main thrust side by (1.5 to 3)λmm, where λ=ι / r, r is the radius of the crankshaft, and ι is the length of the connecting rod.

[0007] Preferably, a main bearing hole is provided on the cylinder block, and the crankshaft is mounted on the main bearing hole.

[0008] Preferably, the crankshaft is provided with a connecting rod journal, one end of the connecting rod big end is mounted on the connecting rod journal, and one end of the small end is connected to the piston via a piston pin.

[0009] The beneficial effects of the present invention are:

[0010] In the eccentric crank-connecting rod structure of the present invention, when the piston is in the power stroke, combustion within the cylinder bore generates gas force, which acts on the piston and is then transmitted to the crankshaft, causing the crankshaft to rotate and output power. During this transmission process, the connecting rod generates a force component relative to the cylinder bore. This force component is proportional to the angle α between the cylinder bore centerline and the connecting rod length. When the crankshaft's rotational centerline deviates toward the main thrust side, the angle α decreases, reducing the force on the main thrust side, thereby reducing friction losses and improving the wear life of the entire machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic structural diagram of an eccentric crank-connecting rod structure provided in an embodiment of the present invention;

[0012] Figure 2 The main thrust side force changes with the crankshaft angle before and after the crankshaft offset.

[0013] In the figure, 1-cylinder block, 2-crankshaft, 3-connecting rod, 4-piston pin, 5-piston, 6-primary thrust side, 7-secondary thrust side. DETAILED DESCRIPTION

[0014] The following is combined with Figure 1-2 The present invention is described in detail with specific embodiments.

[0015] See Figure 1 This embodiment provides an eccentric crank-connecting rod structure, mounted on a cylinder block 1, comprising a crankshaft 2, a connecting rod 3, a piston pin 4, and a piston 5. The crankshaft 2 is mounted on the cylinder block 1, with the connecting rod 3 connected to the crankshaft 2 and the piston pin 4 at opposite ends. The piston 5 is connected to the connecting rod 3 via the piston pin 4. A primary thrust side 6 and a secondary thrust side 7 are provided on opposite sides of the piston 5. The rotational centerline of the crankshaft 2 is offset toward the primary thrust side 6 by (1.5-3)λmm, where λ = ι / r, r is the radius of the crankshaft 2, and ι is the length of the connecting rod 3.

[0016] When the eccentric crank-connecting rod structure of the present invention is in operation, when the piston 5 is in the power stroke, combustion inside the cylinder bore generates a gas force, which acts on the piston 5 and is then transmitted to the crankshaft 2, causing the crankshaft 2 to rotate and output power. During the transmission process, the action of the connecting rod 3 generates a force component relative to the cylinder bore. The centerline of the cylinder bore forms an angle α with the length direction of the connecting rod 3, and the force component is proportional to the angle α. When the rotation centerline of the crankshaft 2 is offset toward the main thrust side 6, the angle α becomes smaller, thereby reducing the force on the main thrust side 6, thereby reducing the friction loss of the entire machine and improving the wear life.

[0017] However, to ensure sufficient power output for the entire engine, the reduction in angle α needs to be controlled within a certain range. Therefore, in this embodiment, the radius of crankshaft 2 is r = 53.45 mm, the length of connecting rod 3 is ι = 159 mm, and the connecting rod ratio is λ = ι / r = 2.975. The controlled offset distance is e2 = (1.5-3)λ mm = 4.5-9 mm, meaning that the rotational centerline of crankshaft 2 is offset from the main thrust side 6 by a distance of 4.5-9 mm. This arrangement ensures operational feasibility while also helping to reduce costs, preventing the problem of excessive offset distances leading to difficult engine installation and high costs.

[0018] As a further preferred embodiment of this embodiment, a main bearing hole is provided in the cylinder block 1, and the crankshaft 2 is mounted in the main bearing hole. The crankshaft 2 is driven by the connecting rod 3 to rotate within the main bearing hole to output power. The main bearing hole can limit the range of motion of the crankshaft 2, preventing it from moving too far and interfering with the operation of other components.

[0019] As a further preferred embodiment of this embodiment, the crankshaft 2 is provided with a connecting rod journal, one end of the large end of the connecting rod 3 is mounted on the connecting rod journal, and one end of the small end is connected to the piston 5 via a piston pin 4. The provision of the connecting rod journal can reduce the friction between the connecting rod 3 and the crankshaft 2 and increase the service life of the connecting rod 3 and the crankshaft 2.

[0020] See Figure 2 , Figure 2 The force acting on the main thrust side 6 before and after the crankshaft 2 is offset varies with the rotation angle of the crankshaft 2. Figure 2 It can be seen that after the crankshaft 2 is offset by 5mm, the maximum reduction in the force acting on the main thrust side 6 is approximately 22.3%. This shows that offsetting the crankshaft 2 can effectively reduce the force acting on the main thrust side 6, thereby reducing friction losses and improving wear life of the entire machine.

[0021] Although the present invention has been described in detail above using specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present invention. Therefore, such modifications or improvements, which do not depart from the spirit of the present invention, are intended to fall within the scope of protection claimed herein.

Claims

1. An eccentric crank connecting rod structure, mounted on a cylinder body (1), characterized in that: The invention comprises a crankshaft (2), a connecting rod (3), a piston pin (4) and a piston (5), wherein the crankshaft (2) is mounted on a cylinder body (1), the opposite ends of the connecting rod (3) are respectively connected to the crankshaft (2) and the piston pin (4), and the piston (5) is connected to the connecting rod (3) via the piston pin (4); the opposite sides of the piston (5) are respectively provided with a main thrust side (6) and a secondary thrust side (7), and the rotation centerline of the crankshaft (2) is offset by (1.5-3)λmm toward the main thrust side (6), wherein λ=ι / r, r is the radius of the crankshaft (2), and ι is the length of the connecting rod (3).

2. The eccentric crank connecting rod structure according to claim 1, characterized in that: A main bearing hole is provided on the cylinder body (1), and the crankshaft (2) is mounted on the main bearing hole.

3. The eccentric crank connecting rod structure according to claim 1, characterized in that: The crankshaft (2) is provided with a connecting rod journal, one end of the large end of the connecting rod (3) is mounted on the connecting rod journal, and one end of the small end is connected to the piston (5) through a piston pin (4).

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