Detection device for simulating service capability of lubricating oil at small end of piston connecting rod of internal combustion engine and working method

Abstract

The detection device comprises a loading support, the bottom end of the loading support is connected with the top end of a piston connecting rod through a locking pressing plate and a nut, a piston pin is arranged in a round hole in the small end of the piston connecting rod in a sleeved mode, and bearings are installed at the two ends of the piston pin respectively. The bearing is fixed in an arc groove in the oil pan and used for supporting the piston pin, so that a certain gap is formed between the small end, arranged on the piston pin in a sleeving mode, of the piston connecting rod and the oil pan, the oil pan is fixed to the supporting base through the oil pan locking nut, and the two L-shaped driving pins are connected to the middle of a concentric-square-shaped frame of the driving connecting rod. And the two driving pins are fixedly connected with the piston pin through fastening nuts. According to the invention, the motion form of a piston pin-connecting rod small-end bushing friction pair in a cylinder is simulated, and the plane reciprocating motion of a traditional testing machine is converted into the motion of reciprocating rotation around a shaft at a certain radian.

Description

Technical Field

[0001] This invention belongs to the field of mechanical technology, and in particular relates to a testing device and working method for simulating the serviceability of lubricating oil at the small end of a piston connecting rod in an internal combustion engine. Background Technology

[0002] In recent years, with the upgrading of oil products and engine technology, the development and launch of long-life engine oils with extended oil change intervals has become an industry consensus as a key component of engine lubrication technology reliability research. Engine manufacturers are constantly proposing to extend engine oil change intervals from the perspectives of protecting engines, reducing maintenance costs, and providing convenience to users. Therefore, in order to better meet the requirements of energy conservation and environmental protection, it is necessary to accelerate the upgrading of oil products, optimize product performance, and extend oil change intervals.

[0003] During normal engine operation, wear between moving components is inevitable. A normal engine sound is a smooth and rhythmic sound. During the piston's cyclical movement within the cylinder, the connecting rod is subjected to regular pulsating force impacts. The contact area between the small end bushing and the piston pin is smaller than the contact area between the big end of the connecting rod and the crankshaft. Therefore, the wear of the small end bushing is of greatest concern compared to the wear of the big end bushing, due to its more severe lubrication conditions. The connecting rod small end bushing uses splash lubrication, aiming to form a lubricating film with normal load-bearing capacity and low tangential shear strength between the friction surfaces, reducing frictional resistance and material wear. However, the splash lubrication method and its oscillating characteristics make it difficult to establish a lubricating film, easily leading to mixed lubrication or even dry friction. This results in abnormal wear, high-temperature erosion, and bushing loosening of the connecting rod small end bushing, causing abnormal engine noises and even serious problems such as piston cracking and cylinder scoring, severely impacting the overall engine operation. Therefore, studying the frictional performance of the connecting rod small end bushing is of great significance, and how to evaluate the frictional performance of lubricating oil under service conditions has become an urgent problem to be solved.

[0004] Regarding the problem of friction and wear on the contact surfaces of moving parts, relatively mature technologies for developing and manufacturing friction and wear testing machines have been established both domestically and internationally. However, dedicated testing benches for friction pairs with special motion patterns (such as the connecting rod small end bushing-piston pin friction pair) are relatively rare. Researchers often use general-purpose testing machines for experimental research. While this method can analyze the friction and wear properties of materials, it ignores the actual motion of the friction pair and cannot obtain the actual lubrication and friction state of the pair during operation. During engine operation, the reciprocating motion of the piston pin relative to the connecting rod small end bushing accelerates the entry of lubricating oil through the internal oil passages of the connecting rod into the connecting rod small end bushing, creating a pumping effect. When conducting friction and wear tests on the connecting rod small end bushing-piston pin, only the oscillating motion is usually considered, ignoring the reciprocating motion of the piston pin within the connecting rod small end bushing caused by bearing clearance. This fails to reflect the pumping effect and significantly impacts the study of the actual lubrication and friction and wear characteristics of the connecting rod small end bushing-piston pin.

[0005] To address the friction and wear problem of piston pin-connecting rod small end bushings, many scholars have built simple friction and wear testing machines and conducted experimental analyses of the wear mechanism based on these machines, providing a theoretical basis for friction and wear control technology. However, most of these testing machines are ring-block testing machines or pin-disc testing machines, which do not provide strong simulation of the piston pin-connecting rod small end bushing assembly. Summary of the Invention

[0006] This invention designs a testing device and working method for simulating the serviceability of lubricating oil at the small end of the piston connecting rod in an internal combustion engine, based on the testing area of ​​a traditional pin-disc or ball-disc friction and wear testing machine (SRV micro-motion friction and wear testing machine). It applies a longitudinal load and tests a transverse reciprocating tensile force. The friction coefficient of the connecting rod small end bushing-piston pin friction pair is calculated by the ratio between the longitudinal load and the transverse tensile force. The magnitude of the friction coefficient is used to detect the mechanical structure of the lubricating oil serviceability at the small end of the piston connecting rod in an internal combustion engine. This structure uses the internal combustion engine piston connecting rod as the test piece to realistically simulate the working conditions of the piston pin-connecting rod small end bushing friction pair within the engine cylinder. It is suitable for rapidly evaluating the serviceability of lubricating oil in the friction pair during the oil product development stage.

[0007] A testing device simulating the service life of lubricating oil in the small end of an internal combustion engine piston connecting rod utilizes a commercially available internal combustion engine piston connecting rod as the test specimen to study the service performance of the lubricating oil. The friction pair between the piston connecting rod and the piston pin is the core of the test. The bearing provides support and bears the radial load. The drive connecting rod and drive pin are used to connect an external power source and a force sensor, providing lateral reciprocating displacement to the device. The loading bracket connects to an external electric loading device for outputting the load. The support base connects to the external force sensor and simultaneously provides longitudinal support force to the oil pan.

[0008] This invention employs the following technical solution: a testing device for simulating the service life of lubricating oil on the small end of an internal combustion engine piston connecting rod, comprising a loading bracket, the bottom end of which is connected to the top end of the piston connecting rod via a locking plate and a nut. A circular hole at the small end of the piston connecting rod fits onto a piston pin, and bearings are installed at both ends of the piston pin. The bearings are fixed within an arc groove on the oil pan, supporting the piston pin and creating a certain gap between the small end of the piston connecting rod fitted onto the piston pin and the oil pan. The oil pan is fixed to a support base via an oil pan locking nut. Two L-shaped drive pins are connected to the middle of a drive connecting rod retaining frame, and the two drive pins are fixedly connected to the piston pin via a fastening nut.

[0009] Furthermore, the loading bracket is connected to an external electric loading device via a flange on top.

[0010] Furthermore, the U-shaped groove at the bottom of the loading bracket is used to accommodate the locking plate and nut.

[0011] Furthermore, the lower end of the support base is mounted on the force sensor of the friction and wear testing machine.

[0012] Furthermore, the drive linkage is connected to a device for horizontal displacement of the test area of ​​the friction and wear testing machine, and is also connected to a force sensor.

[0013] Furthermore, a temperature sensor is installed 10mm above the circular hole at the small end of the piston connecting rod, at a distance from the friction pair.

[0014] A method for operating a testing device that simulates the serviceability of lubricating oil at the small end of a piston connecting rod in an internal combustion engine includes: Step 1: The friction and wear testing machine loads the load along the loading bracket and piston rod onto the contact surface of the piston pin-connecting rod small end bushing friction pair using the loading screw. The friction and wear testing machine provides lateral reciprocating displacement and horizontal tension, converting the lateral reciprocating displacement into the reciprocating rotation of the piston pin around the axis. Step 2: Measure the longitudinal load and lateral tension acting on the piston pin-connecting rod small end bushing friction pair using a force sensor, and calculate the friction coefficient of the piston pin-connecting rod small end bushing friction pair using their ratio. By comparing the magnitude of the friction coefficient, the serviceability of the lubricating oil in the piston connecting rod small end of the internal combustion engine can be indirectly reflected.

[0015] Furthermore, the small end of the piston connecting rod generates a pumping effect during operation, driving the lubricating oil to circulate within the gap. As the piston pin rotates periodically within the small end of the piston connecting rod, the clearance between the round hole at the small end of the piston connecting rod and the piston pin will periodically increase or decrease due to lateral tension and thermal expansion. When the clearance increases, lubricating oil is drawn from the oil sump; conversely, the lubricating oil is discharged from the clearance into the oil sump, simultaneously carrying away heat and wear debris.

[0016] The beneficial effects of this invention are: This invention improves upon the testing areas of traditional pin-disc or ball-disc friction and wear testing machines, overcoming the shortcomings of traditional machines in simulating friction pairs with specific motion characteristics. This invention is used to simulate the piston pin-connecting rod small end bushing friction pair under harsh lubrication conditions within an engine cylinder, enabling rapid performance testing of lubricating oils during the development phase. This shortens the oil development cycle and accelerates oil upgrades. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] Figure 2 for Figure 1 A sectional view.

[0019] Figure 3 This is a schematic diagram of the loading support structure.

[0020] Figure 4 for Figure 3 A cross-sectional view of the loading bracket.

[0021] Figure 5 This is a schematic diagram of the drive linkage structure.

[0022] Figure 6 This is a schematic diagram of the drive pin structure.

[0023] Figure 7 for Figure 6 Sectional view of the drive pin.

[0024] Figure 8 This is a schematic diagram of the oil pan structure.

[0025] Figure 9 This is a cross-sectional view of the oil pan.

[0026] Figure 10 This is an isometric drawing of the present invention.

[0027] In the diagram: 1-Loading bracket, 2-Piston connecting rod, 3-Bearing, 4-Drive connecting rod, 5-Oil pan, 6-Support base, 7-Locking pressure plate, 8-Nut, 9-Piston pin, 10-Drive pin, 11-Fastening nut, 12-Oil pan locking nut, 13-Temperature sensor. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] The device of the present invention simulates the operating conditions of the piston pin-connecting rod small end bushing friction pair in the engine cylinder, and is used to quickly examine the actual service performance of the lubricating oil in the above-mentioned friction pair.

[0030] like Figures 1 to 10As shown, the present invention discloses a testing device for simulating the service life of lubricating oil in the small end of a piston connecting rod of an internal combustion engine. The device includes a loading bracket 1, which is connected to an external electric loading device via a top flange for outputting load. The bottom end of the loading bracket 1 is connected to the top end of the piston connecting rod 2 via a locking plate 7 and a nut 8. A groove at the bottom end of the loading bracket 1 accommodates the locking plate 7 and the nut 8. A circular hole at the small end of the piston connecting rod 2 fits onto a piston pin 9, and bearings 3 are installed at both ends of the piston pin 9. The bearings 3 are fixed in an arc groove on an oil pan 5, supporting the piston pin 9 and creating a certain gap between the small end of the piston connecting rod 2 fitted onto the piston pin 9 and the oil pan 5, allowing the load to act on the piston pin-connecting rod small end bushing friction pair. The oil pan 5 is fixed to a support base 6 via an oil pan locking nut 12. The lower end of the support base 6 is mounted on a force sensor of a friction and wear testing machine, enabling closed-loop control of the load.

[0031] The test area of ​​the friction and wear testing machine undergoes reciprocating displacement in the horizontal direction, causing relative displacement between the pin-disc or ball-disc contact surfaces, forming a friction pair. The drive linkage 4 is connected to the device controlling the horizontal displacement of the test area and also to a force sensor for measuring lateral tensile force. Two L-shaped drive pins 10 are connected to the inner part of the loop frame of the drive linkage 4, and are fixedly connected to the piston pin 9 by a fastening nut 11. The drive linkage 4 and the two L-shaped drive pins 10 convert the horizontal reciprocating displacement of the test area into the reciprocating rotation of the piston pin 9 around its axis. This simulates the contact form of the piston pin-connecting rod small end bushing friction pair. A temperature sensor 13 is installed approximately 10 mm above the circular hole at the small end of the piston connecting rod 2, at a distance from the friction pair, to provide temperature rise parameters of the friction pair.

[0032] The working method of this invention: The friction and wear testing machine uses a loading screw to apply load along the loading bracket 1 and piston connecting rod 2 to the contact surface of the piston pin-connecting rod small end bushing friction pair. Simultaneously, the driving connecting rod 4 is connected to the transverse reciprocating mechanism and force sensor of the friction and wear testing machine, providing transverse reciprocating displacement and horizontal tension. Two L-shaped driving pins 10 are connected to the middle of the loop frame of the driving connecting rod 4, converting the transverse reciprocating displacement into the reciprocating rotation of the piston pin 9 around its axis. Bearings 3 are fitted at both ends of the piston pin 9 and fixed in pre-machined arc grooves on the oil pan 5, allowing the applied load to act on the piston pin-connecting rod small end bushing friction pair. During operation, the longitudinal load and transverse tension acting on the piston pin-connecting rod small end bushing friction pair can be measured by the force sensor. The ratio of these values ​​can be used to calculate the friction coefficient of the piston pin-connecting rod small end bushing friction pair. By comparing the magnitudes of the friction coefficients, the serviceability of the lubricating oil in the small end of the internal combustion engine piston connecting rod can be indirectly reflected.

[0033] The small end of the piston connecting rod generates a pumping effect during operation, driving the lubricating oil to circulate within the gap. As the piston pin 9 rotates periodically within the small end of the piston connecting rod, the clearance between the round hole at the small end of the piston connecting rod and the piston pin 9 will periodically increase or decrease due to lateral tension and thermal expansion. When the clearance increases, lubricating oil is drawn from the oil sump; conversely, the lubricating oil is discharged from the clearance into the oil sump, simultaneously carrying away heat and wear debris.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A testing device for simulating the lubricating oil serviceability of the small end of an internal combustion engine piston connecting rod, comprising a loading bracket, the bottom end of which is connected to the top end of the piston connecting rod via a locking plate and a nut, a circular hole at the small end of the piston connecting rod fitting onto a piston pin, and bearings mounted at both ends of the piston pin, characterized in that... The bearing is fixed in the arc groove on the oil pan. The bearing is used to support the piston pin, so that the small end of the piston rod sleeved on the piston pin forms a certain gap with the oil pan. The oil pan is fixed to the support base by the oil pan locking nut. The two L-shaped drive pins are connected to the middle of the loop frame of the drive rod. The two drive pins are fixedly connected to the piston pin by the fastening nut.

2. The apparatus according to claim 1, characterized in that, The loading bracket is connected to an external electric loading device via a flange at the top.

3. The apparatus according to claim 1, characterized in that, The groove at the bottom of the loading bracket is used to accommodate the locking plate and nut.

4. The apparatus according to claim 1, characterized in that, The lower end of the support base is mounted on the force sensor of the friction and wear testing machine.

5. The apparatus according to claim 1, characterized in that, The drive linkage is connected to a device for horizontal displacement of the test area of ​​the friction and wear testing machine, and is also connected to a force sensor.

6. The apparatus according to claim 1, characterized in that, A temperature sensor is installed 10 mm above the round hole at the small end of the piston connecting rod, at a distance from the friction pair.

7. A method for operating a testing device that simulates the serviceability of lubricating oil at the small end of a piston connecting rod in an internal combustion engine, characterized in that... include: Step 1: The friction and wear testing machine loads the load along the loading bracket and piston rod onto the contact surface of the piston pin-connecting rod small end bushing friction pair using the loading screw. The friction and wear testing machine provides lateral reciprocating displacement and horizontal tension, converting the lateral reciprocating displacement into the reciprocating rotation of the piston pin around the axis. Step 2: Measure the longitudinal load and lateral tension acting on the piston pin-connecting rod small end bushing friction pair using a force sensor, and calculate the friction coefficient of the piston pin-connecting rod small end bushing friction pair using their ratio. By comparing the magnitude of the friction coefficient, the serviceability of the lubricating oil in the piston connecting rod small end of the internal combustion engine can be indirectly reflected.

8. The method according to claim 7, characterized in that, It also includes the pumping effect generated at the small end of the piston connecting rod during operation, which drives the lubricating oil to circulate within the gap. When the piston pin rotates periodically within the small end of the piston connecting rod, the clearance between the round hole at the small end of the piston connecting rod and the piston pin will periodically increase or decrease due to lateral tension and thermal expansion. When the clearance increases, lubricating oil is drawn from the oil sump; conversely, the lubricating oil is discharged from the clearance into the oil sump, while carrying away heat and wear debris.

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