Lubricating optimization device for connecting rod of diesel engine and three-section connecting rod of medium-speed diesel engine

Abstract

The invention discloses a lubrication optimization device for a diesel engine connecting rod, and belongs to the technical field of diesel engine lubrication. The valve seat is fixed in the valve body, a guide spherical surface is arranged at the end of the valve seat, and the steel ball rolls back and forth between the guide spherical surface of the valve seat and a sealing limiting surface in the valve body under the action of driving force generated by oil pressure difference, so that the flowing sectional area of lubricating oil is dynamically changed, and automatic throttling is achieved. The oil quantity is automatically adjusted through a pure mechanical structure, the cooling oil quantity supplied to a piston can be accurately controlled, impact of lubricating oil backflow on a bearing bush oil film at the large end of the connecting rod can be effectively prevented, the reliability and durability of lubricating of the connecting rod are improved, the structure is compact, installation is easy and convenient, and the three-section type connecting rod is suitable for various medium-speed diesel engines.

Description

Technical Field

[0001] This invention relates to the field of lubrication technology for moving parts of diesel engines, and in particular to a lubrication optimization device for connecting rods of diesel engines, especially suitable for oil supply control and oil film protection between connecting rods and pistons in high-power medium-speed diesel engines. Background Technology

[0002] As a key moving component in a diesel engine, the connecting rod plays a crucial role in transmitting the gas forces acting on the piston to the crankshaft. During the continuous intake, compression, expansion, and exhaust cycles of a diesel engine, the piston-connecting rod assembly undergoes high-speed reciprocating motion, requiring effective lubrication and cooling from lubricating oil. In traditional designs, lubricating oil flows from the crankshaft oil passages into the large end of the connecting rod, and then is transported to the small end of the connecting rod via internal oil passages within the connecting rod body, ultimately lubricating the piston.

[0003] For three-section connecting rod structures, a forked bidirectional oil passage is typically designed at the large end to facilitate oil passage machining. This involves opening oil holes with a diameter of Ø16 on both sides of the large end, allowing the lubricating oil from both sides to converge into the main oil hole with a diameter of Ø25 at the center of the connecting rod body. However, this structure has significant drawbacks in actual operation: firstly, the actual cooling oil required by the piston is usually 3~5 g / kW·h, while the original oil passage design results in an oil supply exceeding the demand; secondly, during the upward movement of the connecting rod, the lubricating oil flows downward due to inertia, impacting the oil film formed within the connecting rod bearing, severely affecting the stability of the oil film and the service life of the connecting rod bearing, and even causing problems such as cavitation.

[0004] Therefore, there is an urgent need for a new type of lubrication control device that can effectively suppress oil backflow and protect the oil film at the large end of the connecting rod while ensuring the required amount of cooling oil for the piston, so as to improve the reliability of diesel engine operation and the life of components. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing three-stage connecting rod lubrication systems and provide a lubrication optimization device for diesel engine connecting rods. This device aims to precisely control the amount of cooling oil supplied to the piston, while effectively preventing the backflow of lubricating oil caused by the high-speed movement of the connecting rod during diesel engine operation from impacting the oil film on the connecting rod's large-end bearing. This improves the reliability of the connecting rod bearing and extends its service life while ensuring sufficient piston cooling and lubrication.

[0006] The technical solution of the present invention is as follows: On one hand, the present invention provides a lubrication optimization device for a diesel engine connecting rod, installed in the oil passage of the connecting rod large end cap, characterized in that the device comprises: The valve body is cylindrical, and its outer wall is press-fitted with the lubricating oil passage. The valve seat is fixedly installed inside the oil inlet end of the valve body. It has an axial oil passage, and the end of the oil passage facing the inside of the valve body forms a guide spherical surface that is adapted to the outer diameter of the steel ball. The steel ball is housed within the cavity formed by the valve body and the valve seat; The steel ball can reciprocate between the guide ball and the sealing limiting surface inside the valve body under the pressure of the lubricating oil flowing through the valve seat. When the steel ball is pressed against the sealing limiting surface, the flow of lubricating oil is cut off or restricted. When the steel ball leaves the sealing limiting surface and moves along the guide ball, the lubricating oil flows through the gap between the guide ball and the steel ball and the gap between the steel ball and the inner wall of the valve body, realizing dynamic throttling based on oil pressure difference.

[0007] Furthermore, the valve seat and valve body are fixedly connected by an interference fit, and together they form an independent, pre-assembleable valve module.

[0008] Furthermore, the guide spherical surface is configured to guide and center the reciprocating rolling steel ball, and when the steel ball is in contact with it, form an annular maximum flow channel that allows lubricating oil to flow around the outer surface of the steel ball.

[0009] Furthermore, the sealing and limiting surface is a spherical surface, a conical surface, or an annular plane that is adapted to the outer diameter of the steel ball.

[0010] Furthermore, the radial gap between the steel ball and the inner wall of the valve body is 0.2 mm to 0.4 mm.

[0011] Furthermore, the valve seat and valve body are made of alloy structural steel and have undergone surface hardening treatment, and the steel balls are finished high-carbon chromium bearing steel balls.

[0012] Secondly, the present invention also provides a three-section connecting rod for a medium-speed diesel engine, including a large end cap for the connecting rod. The large end cap has a transverse channel connecting the crankshaft oil inlet passage and the connecting rod small end oil supply passage. The feature is that a lubrication optimization device as described above is installed in the transverse channel. The device is configured to automatically limit the excessive supply of lubricating oil to the small end of the connecting rod when the movement of the connecting rod causes changes in the oil pressure at both ends, and to prevent the lubricating oil from flowing back and impacting the oil film of the connecting rod large end bearing.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1) In the three-stage connecting rod lubrication system, "free steel balls" are introduced as pressure sensing and throttling valve cores. By utilizing their automatic displacement under different oil pressures, intelligent on / off switching and flow regulation of the lubrication circuit are realized.

[0014] 2) Dynamic throttling ensures that the amount of cooling oil supplied to the piston remains stable within the required range (3~5g / kW / h), avoiding energy loss and lubrication system burden caused by excessive oil supply. It effectively suppresses the downward backflow of lubricating oil during connecting rod upward movement, greatly reducing the impact of the backflowing oil on the oil film of the connecting rod's large end bearing, thereby effectively preventing oil film rupture and cavitation, and significantly improving the bearing's operational reliability and lifespan.

[0015] 3) While ensuring the piston oil supply, it avoids the impact of lubricating oil backflow on the connecting rod bearing oil film during high-speed connecting rod movement. Operation is simple, reliable, and safe. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the crankshaft connecting rod piston connection with the connecting rod lubrication optimization device installed.

[0017] Figure 2 This is a schematic diagram of the throttling device assembly.

[0018] Figure 3 This is a schematic diagram of the throttling device.

[0019] Figure 4 This is a schematic diagram of the exploded structure of a throttling device. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are intended to help those skilled in the art fully understand the technical solutions and implementation details of the present invention, but are not intended to limit the scope of protection of the present invention.

[0021] 1. Confirmation and preparation of installation location like Figure 1 As shown, the throttling device 4 of this invention is installed in the large end cap of a three-section connecting rod. Before installation, it is necessary to confirm that there is an installation channel on the large end cap connecting the crankshaft oil inlet passage and the transverse oil passage. This channel is confirmed to be a cylindrical hole with a length of 55mm and a diameter of Ø31H7. This channel is the standard mounting base for this device.

[0022] 2. Assembly process of the throttling device Pre-assembled valve module: First, the valve seat 5 is pressed into the inner hole of the valve body 6 with its outer wall to form an interference fit, thereby pre-assembling it into an independent valve module containing an internal cavity. This step can be completed offline in a clean environment to ensure assembly quality.

[0023] Insert steel ball: Insert steel ball 7 into the central oil passage of the valve module from the other end of the valve body 6.

[0024] integral press-fit connecting rod: such as Figure 2As shown, align the assembled throttling device 4 with its outer diameter Ø31s6, and the mounting channel with a diameter of Ø31H7 on the large end cap of the connecting rod. Apply axial force using a soft wooden hammer or special tooling to smoothly press it into the channel until it is fully in place. The fit between Ø31s6 and Ø31H7 is an interference fit, which ensures that the device will not loosen or shift under high-speed and high-impact conditions.

[0025] 3. Functions and Collaborative Relationships of Core Components See Figure 3 and Figure 4 The functions and collaborative relationships of the three core components are as follows: Valve seat 5: Its core function lies in the guide spherical surface designed at its end. This spherical surface not only forms a seal by being tangent to the steel ball 7, but more importantly, it guides and centers the movement of the steel ball 7. When the steel ball 7 is in contact with this spherical surface, lubricating oil can flow around the steel ball 7 along the spherical surface, forming an annular maximum flow channel.

[0026] Valve body 6: The end of its interior furthest from the valve seat forms a sealing and limiting surface. This surface can be designed as a spherical, conical, or annular plane that matches the outer diameter of the steel ball. When the steel ball 7 is in contact with this surface under oil pressure, it can effectively cut off or greatly restrict the flow of lubricating oil.

[0027] Steel ball 7: A moving part, its diameter is slightly smaller than the valve body's inner diameter, forming a radial clearance of 0.2mm to 0.4mm. This ensures the flexible rolling of the steel ball and also constitutes part of the throttling channel.

[0028] 4. Dynamic description of the work process Combination Figure 1 The operation of this device is entirely controlled automatically by the system's hydraulic pressure. During normal oil supply: When the diesel engine requires cooling oil to be supplied to the piston, the lubricating oil pressure from the crankshaft 1 pushes the steel ball 7 to overcome resistance and roll towards the valve body 6. If the oil demand is large, the steel ball 7 moves away from the valve seat 5, and the lubricating oil flows smoothly to the small end of the connecting rod through the aforementioned gap.

[0029] Flow restriction and throttling stage: When the connecting rod movement causes a momentary increase in the oil pressure at its large end (such as when upward movement may cause backflow impact), or when the oil volume required by the piston decreases, the pressure on the oil outlet side of the device increases, pushing the steel ball 7 to roll back towards the valve seat 5. The rolling of the steel ball 7 dynamically changes the flow cross-sectional area, achieving dynamic throttling. If the return oil pressure is large enough, the steel ball 7 will be completely pressed against the sealing limit surface of the valve body 6, achieving unidirectional cutoff, thereby effectively protecting the oil film of the connecting rod large end bearing from impact.

[0030] 5. Implementation details of key process and material selection Valve seat 5 and valve body 6: Made of alloy structural steel CrNiW. This material has good core toughness to absorb impact energy. Furthermore, the guide spherical surface and sealing limiting surface that contact the steel ball 7 must undergo surface hardening treatments such as carburizing or nitriding to achieve a surface hardness of HRC 58 or higher, providing extremely high wear resistance and anti-adhesion capabilities to withstand repeated impacts and rolling of the steel ball.

[0031] Steel ball 7: Commercially available GCr15 high carbon chromium bearing steel finished steel balls with a precision grade not lower than G10 grade in GB / T 308-2002 to ensure dimensional accuracy, spherical error and sufficient fatigue strength.

Claims

1. A lubrication optimization device for a diesel engine connecting rod, installed in the oil passage of the connecting rod large end cap, characterized in that, The device includes: The valve body (6) is cylindrical, and its outer wall is press-fitted with the lubricating oil passage. The valve seat (5) is fixedly installed inside the oil inlet end of the valve body (6), and it is provided with an axial oil passage. The end of the oil passage facing the inside of the valve body forms a guide spherical surface that is compatible with the outer diameter of the steel ball. The steel ball (7) is housed in the cavity formed by the valve body (6) and the valve seat (5); The steel ball (7) can reciprocate between the guide ball surface and the sealing limiting surface inside the valve body (6) under the action of the lubricating oil pressure flowing through the valve seat (5); when the steel ball (7) is pressed against the sealing limiting surface, the flow of lubricating oil is cut off or restricted; when the steel ball (7) leaves the sealing limiting surface and moves along the guide ball surface, the lubricating oil flows through the gap between the guide ball surface and the steel ball (7) and the gap between the steel ball (7) and the inner wall of the valve body (6), thereby realizing dynamic throttling based on oil pressure difference.

2. The lubrication optimization device according to claim 1, characterized in that, The valve seat (5) and the valve body (6) are fixedly connected by an interference fit and together form an independent, pre-assembleable valve module.

3. The lubrication optimization device according to claim 1, characterized in that, The guide sphere is configured to guide and center the reciprocating rolling steel ball (7), and when it is in contact with the steel ball (7), it forms an annular maximum flow channel that allows lubricating oil to flow around the outer surface of the steel ball (7).

4. The lubrication optimization device according to claim 1, characterized in that, The sealing limiting surface is a spherical surface, conical surface, or annular plane that is adapted to the outer diameter of the steel ball (7).

5. The lubrication optimization device according to claim 1, characterized in that, The radial gap between the steel ball (7) and the inner wall of the valve body (6) is 0.2 mm to 0.4 mm.

6. The lubrication optimization device according to any one of claims 1 to 5, characterized in that, The valve seat (5) and valve body (6) are made of alloy structural steel and have undergone surface hardening treatment, and the steel ball (7) is a finished ball of high carbon chromium bearing steel.

7. A three-section connecting rod for a medium-speed diesel engine, comprising a large end cap for the connecting rod, wherein the large end cap has a transverse channel connecting the crankshaft oil inlet passage and the connecting rod small end oil supply passage, characterized in that, The transverse channel is equipped with a lubrication optimization device as described in any one of claims 1 to 6, the device being configured to: automatically limit the excessive supply of lubricating oil to the small end of the connecting rod when the movement of the connecting rod causes a change in oil pressure at both ends, and prevent the lubricating oil backflow from impacting the oil film of the bearing at the large end of the connecting rod.

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