CN206862627U - Fatigue durability testing device for engine connecting rod - Google Patents

Abstract

An engine connecting rod fatigue durability test device, including a drive motor, a hydraulic cylinder, a flywheel, a guide rod, a connecting rod durability test unit and a connecting rod clamping mechanism, the connecting rod durability test unit includes a camshaft, a first cam, and a second cam , the first drive arm, the second drive arm and the intermediate shaft, one end of the first drive arm is attached to the first cam through the first drive arm bearing, and the first drive arm is provided with the first drive arm conversion wheel and the second drive arm A driving arm carrying wheel, the second driving arm is attached to the second cam through the second driving arm bearing, the second driving arm is provided with a second driving arm conversion wheel and a second driving arm carrying wheel, and the connecting rod is durable There is a push rod connected to the hydraulic cylinder on the center hole of the conversion wheel of the second driving arm of the test unit. The upper end of the guide rod is fastened to the output end of the second driving arm load wheel through a nut. The upper end of the guide rod is provided with a spring upper seat, and the spring upper seat A bearing spring is arranged between the cylinder sleeve and the cylinder sleeve. The utility model has high test frequency, short test period, and little difference between the test result and the actual use, and can fully test whether the design of the connecting rod meets the endurance life.

Description

Engine Connecting Rod Fatigue Durability Test Device

technical field

The utility model relates to a test device, in particular to a fatigue durability test device for an engine connecting rod, which is mainly used for the fatigue durability detection of an automobile engine connecting rod.

Background technique

The connecting rod is an important part of the engine that transmits power. It converts the linear motion of the piston into the rotary motion of the crankshaft and bears a large mechanical load. The small end of the connecting rod is connected with the piston pin and reciprocates with the piston; the crank pin of the connecting rod is connected with the crank pin and rotates with the crankshaft. The basic load on the connecting rod is tension and compression, and the maximum tension load occurs at the Near the top dead center at the beginning of the air stroke, it is mainly the reciprocating inertial force generated by the piston and the part above the big end of the connecting rod; the maximum compression force appears near the top dead center of the power stroke, mainly due to the explosive pressure on the piston, which is quite large . In addition, due to the tangential inertial force generated by the left and right swing of the connecting rod, the connecting rod is subjected to additional bending moments, and these forces change periodically, forming an alternating load.

At present, the connecting rod fatigue durability test is carried out on a special connecting rod hydraulic servo fatigue testing machine. The testing machine usually uses a hydraulic device to simulate the relevant loads on the engine connecting rod under operating conditions. There is no impact on the sample during the loading process. A gap is allowed during the loading process of the sample. The purpose of the test is mainly to analyze the fatigue load of the connecting rod, but the frequency of the test is low, generally not higher than 30 Hz, and the overall period of the test is longer. This fatigue test is usually used as a part of the component production process. The main verification method is mainly applied to the preliminary test of the prototype in the early stage of engine development. Further verification of the overall durability test of the engine is required to determine whether the connecting rod meets the overall durability life requirements.

In addition, because the hydraulic servo durability test device requires an interference fit between the small end of the connecting rod and the pin, no lubricating oil can be filled between the small end of the connecting rod and the piston pin. There is a big difference in the working conditions, which affects the judgment of the test results.

Therefore, the current engine connecting rod durability test device has the problems of low test frequency, long test period, large differences between the loading conditions during the actual test process and the actual working conditions, and large differences between the test results and the actual use.

Utility model content

The purpose of the utility model is to provide an engine connecting rod fatigue durability test device, which not only has high test frequency and short test period, but also has little difference between test results and actual use.

The technical solution for realizing the purpose of this utility model is: a kind of engine connecting rod fatigue endurance testing device, comprising driving motor, hydraulic cylinder, flywheel, guide rod, connecting rod durability testing unit and connecting rod clamping mechanism, connecting rod clamping mechanism comprises Piston, piston pin, crank pin and crankshaft, the piston is fixed in the cylinder liner through the piston ring, the connecting rod is connected with the piston through the piston pin, the big end of the connecting rod is fixed on the crank pin of the crankshaft, the connecting rod durability test unit includes the camshaft , the first cam, the second cam, the first driving arm, the second driving arm and the intermediate shaft, one end of the first driving arm is attached to the first cam through the first driving arm bearing, and the first driving arm is provided with The first driving arm conversion wheel and the first driving arm bearing wheel, the first driving arm bearing wheel is installed on the intermediate shaft, the second driving arm is attached to the second cam through the second driving arm bearing, and the second driving arm is provided with There is a second driving arm conversion wheel and a second driving arm bearing wheel, the second driving arm bearing wheel is installed on the intermediate shaft, and the center hole of the second driving arm conversion wheel of the connecting rod durability test unit is connected with the hydraulic cylinder The upper end of the guide rod is fastened to the output end of the load wheel of the second driving arm through a nut, the upper end of the guide rod is provided with a spring upper seat, and a load spring is arranged between the spring upper seat and the cylinder liner.

Adopting the above-mentioned technical scheme, the utility model has the following beneficial effects:

The utility model realizes the high-speed and durable operation of the connecting rod fatigue durability test device by setting a set of cam transmission high-frequency device. At the same time, the device can use several series to work, and can detect 3 to 4 connecting rods at a time. The durability test time is shortened; in addition, the entire test device simulates the working process of the engine, and the load received during the test is close to the actual work of the connecting rod, which can fully test whether the design of the connecting rod meets the durability life, and avoids the subsequent verification of the whole machine. After solving the problem, modify the design of the connecting rod to ensure the overall schedule and time requirements of the project.

Description of drawings

Fig. 1 is the top view of the working state of the engine connecting rod fatigue durability testing device of the present invention;

Fig. 2 is the schematic diagram of the first working state of the engine connecting rod fatigue durability testing device of the present invention;

Fig. 3 is the schematic diagram of the second working state of the engine connecting rod fatigue durability testing device of the present invention;

Fig. 4 is the schematic diagram of the third working state of the engine connecting rod fatigue durability testing device of the present invention;

Fig. 5 is the top view of the utility model engine connecting rod fatigue endurance test device simulating the working state of engine knocking;

Fig. 6 is a schematic diagram of the simulated engine knock state of the engine connecting rod fatigue endurance test device of the present invention.

Among the figure, 1-camshaft; 2-first cam; 3-second cam; 4-drive motor; 5-second drive arm; 51-second drive arm bearing; 52-second drive arm conversion wheel; 53 - second drive arm load wheel; 6 - hydraulic cylinder; 61 - push rod; 7 - flywheel; 8 - guide rod; 9 - spring upper seat; 10 - cylinder liner; 11 - intermediate shaft; 12 - first drive arm; 121 -the bearing of the first driving arm; 122-the conversion wheel of the first driving arm; 123-the bearing wheel of the first driving arm; 13-loading spring; 14-piston; 15-piston pin; 16-connecting rod; 17-crank pin; 18 - crankshaft; 19 - piston rings.

detailed description

In order to make the content of the utility model more clearly understood, the utility model will be further described in detail below based on specific embodiments and in conjunction with the accompanying drawings.

The connecting rod is one of the most important parts of the engine. In order to make the engine compact, the most suitable length of the connecting rod should be to select a small one while ensuring that the connecting rod and related parts do not collide with other parts when they move. The length of the connecting rod, and the medium and low speed diesel engine with large cylinder diameter, in order to reduce the side pressure, the connecting rod can be lengthened appropriately. The structure of the connecting rod is not complicated, and the size of the big end and small end of the connecting rod mainly depends on the design of the crankshaft and the piston group. In the design of the connecting rod, the main consideration is the center distance of the connecting rod and the structural form of the large and small heads. The movement and stress state of the connecting rod are more complicated. During the operation of the internal combustion engine, the center of the small head of the connecting rod reciprocates together with the piston to bear the reciprocating inertia force generated by the piston group; the center of the big end reciprocates together with the connecting rod journal of the crankshaft to bear the reciprocating inertia force of the piston and connecting rod The rotating mass inertia force of the connecting rod group excluding the big head cover of the connecting rod; the rod body moves in a compound plane and bears the tension and compression alternating stress generated by gas pressure and reciprocating inertia force, as well as the compression load and its own swing inertia moment The resulting additional bending stress.

In order to comply with the trend of high-speed internal combustion engines, the development of new materials, new processes and new structures of connecting rods must not only help improve stiffness and fatigue strength, but also reduce mass and size.

As shown in Figures 1 and 2, an engine connecting rod fatigue durability test device includes a drive motor 4, a hydraulic cylinder 6, a flywheel 7, a guide rod 8, a connecting rod durability test unit and a connecting rod clamping mechanism, and the connecting rod durability test The unit includes a camshaft 1, a first cam 2, a second cam 3, a first driving arm 12, a second driving arm 5 and an intermediate shaft 11. One end of the first driving arm 12 is attached to the first driving arm bearing 121. On the cam 2, the first driving arm 12 is provided with a first driving arm conversion wheel 122 and a first driving arm carrying wheel 123, and the first driving arm carrying wheel 123 is installed on the intermediate shaft 11; the second driving arm 5 passes through the first driving arm Two drive arm bearings 51 are fitted on the second cam 3, and the second drive arm 5 is provided with a second drive arm conversion wheel 52 and a second drive arm carrying wheel 53, and the first drive arm carrying wheel 123 and the second drive arm The load wheel 53 is installed on the intermediate shaft 11, and the upper end of the guide rod 8 is fastened to the output end of the second drive arm load wheel 53 by a nut. There is a bearing spring 13, a push rod 61 connected to the hydraulic cylinder 6 is arranged on the center hole of the conversion wheel 52 of the second driving arm, and the connecting rod clamping mechanism includes a piston 14, a piston pin 15, a crank pin 17, a crankshaft 18, and a piston 14 The piston ring 19 is fixed in the cylinder liner 10 , the connecting rod 16 is connected to the piston 14 through the piston pin 15 , and the big end of the connecting rod 16 is fixed on the crank pin 17 of the crankshaft 18 .

In addition, when there are a large number of tests, in order to save test time, several test units are connected in series to the same drive motor and load pump to realize simultaneous online test of 3 to 4 connecting rods at a time. In addition, the cooling oil injection system on the piston pin (not shown in the figure) can truly simulate the actual working state of the connecting rod, and verify the durability and reliability of the connecting rod to the greatest extent.

The working principle of the engine connecting rod fatigue endurance testing device will be described below in conjunction with the accompanying drawings.

As shown in Figure 2, when the camshaft 1 drives the second cam 3 to move from the base circle position to the cam maximum lift position, the second driving arm 5 moves upward, and the output end of the second driving arm bearing wheel 53 drives the guide rod 8 moves downward, thereby driving the spring upper seat 9 to compress the bearing spring 13 downward, and at the same time drive the piston 14 and the small end of the connecting rod 16 to move linearly downward. At this time, the large end of the connecting rod 16 and the crank pin 15 rotate to the bottom position together. The flywheel 7 starts to rotate under the action of the crankshaft; at this time, the first driving arm bearing 121 is attached to the bottom end of the base circle of the first cam 2 and is in idling, and the connecting rod is mainly subjected to a compressive load.

As shown in Figures 3 and 4, when the second cam 3 moves to the base circle position, the guide rod 8 moves upward under the action of the return spring force of the bearing spring 15, and at the same time drives the piston 14 and the small end of the connecting rod 16 to make a straight line upward. At this time, the big end of the connecting rod 16 and the crank pin 15 rotate to the top position together. At this time, the first driving arm bearing 121 moves to the maximum lift position of the first cam 2, and it is still idling, and the connecting rod is mainly stretched. load. In this way, one endurance test cycle is completed, and then enters the next test cycle.

At present, in the process of connecting rod design, a certain safety factor is usually reserved. The general durability test is only carried out according to its actual working conditions. , and swing left and right, making complex plane movements. Therefore, it is necessary to do some enhanced durability tests to ensure the durability of the connecting rod.

As shown in Figure 5, when the hydraulic cylinder 6 drives the push rod 61 to move, the first driving arm switching wheel 122 and the second driving arm switching wheel 52 are connected in series, since the maximum lift of the first cam 2 is greater than that of the second cam 3. At this time, the durability test device conducts the durability test under the guidance of the first cam 2 .

As shown in Figure 6, when it is at the maximum lift position of the first cam 2, the compression amount of the load spring 15 is greater at this time, and its subsequent return elastic force is also greater; for the detected connecting rod, it is stretched and compressed The load increases accordingly, which further verifies the reliability of the connecting rod design and ensures the smooth progress of the project progress.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present utility model in detail. It should be understood that the above descriptions are only specific embodiments of the present utility model and are not intended to limit the present invention. For the utility model, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the utility model shall be included in the protection scope of the utility model.

Claims (1)

1. a kind of engine link fatigue durability testing device, including motor (4), hydraulic cylinder (6), flywheel (7), guide rod (8), connecting rod durable test unit and connecting rod clamping mechanism, connecting rod clamping mechanism include piston (14), piston pin (15), crankpin (17) it is fixed on bent axle (18), piston (14) by piston ring (19) in cylinder sleeve (10), connecting rod (16) passes through piston pin (15) It is connected with piston (14), the stub end of connecting rod (16) is fixed on the crankpin (17) of bent axle (18), it is characterised in that：Connecting rod is resistance to Long test cell includes camshaft (1), the first cam (2), the second cam (3), the first actuating arm (12), the second actuating arm (5) With jackshaft (11), one end of the first actuating arm (12) is fitted on the first cam (2) by the first actuating arm bearing (121), The first actuating arm (12) is provided with the first actuating arm conversioning wheel (122) and the first actuating arm bearing wheels (123), the first driving simultaneously Arm bearing wheels (123) are arranged on jackshaft (11), and the second actuating arm (5) is fitted in second by the second actuating arm bearing (51) On cam (3), the second actuating arm (5) is provided with the second actuating arm conversioning wheel (52) and the second actuating arm bearing wheels (53), and second Actuating arm bearing wheels (53) are arranged on jackshaft (11), the second actuating arm conversioning wheel (52) of the connecting rod durable test unit Centre bore on have a push rod (61) being connected with hydraulic cylinder (6), guide rod (8) upper end is fastened on the second actuating arm by nut and carried The output end of (53) is taken turns, guide rod (8) upper end is provided with the spring seat of honour (9), and carrying bullet is provided between the spring seat of honour (9) and cylinder sleeve (10) Spring (13).