RU2025694C1 - Method of measurement of clearances in crank gear bearings of internal combustion engine - Google Patents

Abstract

FIELD: mechanical engineering; internal combustion engine maintenance. SUBSTANCE: engine crankshaft is turned through 720 degrees, minimum value of torque is found and crankshaft is set in this position. Then crankshaft is turned in opposite direction applying a torque equal to crankshaft antitorque moment with pistons disconnected. Then torque is increased successively n-1 times by value required for moving one piston in cylinder n being number of cylinders in engine. At each value of torque crankshaft angle is measured and clearances are found by angles of turning. EFFECT: increased accuracy and reduced expenses for checking.

Description

 The invention relates to technical diagnostics, and in particular to methods for measuring the clearances in bearings of the crank mechanism of crankshaft) internal combustion engines (ICE).

 Known methods for measuring the clearances in bearings of KShM, based on the fixation of the distances of movement of the piston, both when the engine is stationary, and when the crankshaft rotates.

 When these methods are implemented, complex and expensive measuring instruments are required - tensometric, vibration-measuring, and other equipment, a significant amount of preparatory operations, soot on the engine pistons and the presence of a lubricant layer in the sliding bearings have a significant effect on the measurement error.

 The closest technical solution, selected as a prototype, is a method for measuring gaps in conjugate crankshaft, implemented in the device KI-13933 GOSNITI and consisting in determining the height difference of the TDC of the piston at starting and maximum revolutions of the crankshaft.

 However, the known method has the following disadvantages: the high complexity of the preparatory work, since it requires removal of the nozzles from the engine and the installation of a measuring device in their place. In addition, the limitation of measurement time at maximum crankshaft revolutions (not more than 30 s) requires a highly qualified conductive measurement.

 The aim of the invention is to improve the accuracy and reduce the cost of monitoring the technical condition of the internal combustion engine.

This is achieved in that the crank of the engine crankshaft 720 ^of determining the minimum torque value and set the shaft in this position. This ensures the constancy of the measuring base.

 Then crank the crankshaft in the opposite direction, applying a torque equal to the moment of resistance to cranking the crankshaft without pistons.

 This moment is determined by cranking the crankshaft within the nominal total clearance in the upper and lower connecting rod bearings (0.18 ... 0.29 mm). Within this clearance, the engine pistons do not move.

 Then the torque is successively increased by the amount necessary to move one piston in the cylinder as many times as there are cylinders in the engine minus one, and the angle of rotation of the crankshaft is measured at each torque value.

, где M_п - крутящий момент сопротивления перемещению одного поршня;
M - наименьший крутящий момент проворачивания коленчатого вала двигателя;
M_o - крутящий момент проворачивания вала дизеля без поршней;
n - количество цилиндров дизеля.The moment of resistance to movement of one piston is determined by the dependence:
M _p =

where M _p - torque resistance to movement of one piston;
M is the smallest cranking torque of the engine;
M _o - the torque of rotation of the diesel shaft without pistons;
n is the number of diesel cylinders.

 This provides a choice of gaps in the upper and lower heads of each individual engine connecting rod. The angle of rotation of the crankshaft at appropriate torques will serve as a measure of the indicated clearances.

 If at least one of the total clearances exceeds the standard value, the engine must be disassembled in order to determine the location of the defect. The method can be carried out using a torque arm equipped with an optical goniometer. Installation of the device is carried out once on the engine crankshaft pulley. Measurement can also be carried out by a special programmable electric motor.

 This ensures a reduction in control costs and a reduction in control costs and ensures the required measurement accuracy, since there is no need for preparatory work for each cylinder, the lubricant layer in the bearings is constant, soot on the piston does not affect the measurement.

 PRI me R. The measurement was carried out on a YaMZ-238NB diesel engine of the Kirovets K-700A tractor. The following were used: a torque wrench DK-0,1, a dial indicator ICh-IOMN, a tripod for KI-1871.01 indicator. Using a torque wrench, the diesel crankshaft rotated two turns through the fan drive pulley. The minimum torque value was established, which in this case was 5.3 kgcm.

 A tripod with a dial gauge was fixed on the diesel block, and the indicator leg was mounted in the edge of the dynamometer lever at a distance from the shaft rotation center of 140 mm (two radii of the crankshaft of the diesel crankshaft).

= 0,45 кгсм,
Для удобства отсчета этот момент принят равным 0,5 кГсм. После этого динамометрический рычаг возвращался в исходное положение (показание индикатора "0") и последовательно прикладывался в обратную сторону крутящий момент равный 1,8; 0,5; 0,5; 0,5; 0,5; 0,5; 0,5; 0,5 кг. Крутящий момент 1,8 кгсм получен путем увеличения момента 1,7 кгсм на 0,1 кгсм (20% от 0,5 кгсм) для более полного выбора зазора в сопряжении при неподвижном положении поршней.Then the diesel crankshaft was rotated in the opposite direction by the amount of rotation of the dynamometer lever equal to 0.20 mm, the nominal total clearance in the bearings in the upper and lower heads of the connecting rod), and at the same time a torque was fixed, which turned out to be equal to 1.7 kG. After that, the moment was determined, which turned out to be equal to 1.7 kgf. After that, the moment of resistance to the displacement of one piston was determined according to the above formula:
M _p =

= 0.45 kgcm,
For the convenience of reference, this moment is taken equal to 0.5 kgf. After that, the dynamometer lever returned to its original position (indicator reading "0") and a torque equal to 1.8 was applied sequentially in the opposite direction; 0.5; 0.5; 0.5; 0.5; 0.5; 0.5; 0.5 kg A torque of 1.8 kgcm was obtained by increasing the torque of 1.7 kgcm by 0.1 kgcm (20% of 0.5 kgcm) for a more complete selection of the clearance in conjugation with the pistons stationary.

 At each value of the torque, a shutter speed of 3-6 s was made and the indicator reading was read, which turned out to be equal to: 0.22; 0.23; 0.23; 0.25; 0.25; 0.26; 0.26. An analysis of these data shows that the technical condition of the bearings of the crank mechanism of the diesel engine is within acceptable limits.

Claims (1)

METHOD FOR MEASURING CLEARANCES IN BEARINGS OF CRANKSHAFT MECHANISM OF INTERNAL COMBUSTION ENGINE, characterized in that, in order to increase accuracy and reduce control costs, crank the engine crankshaft by 720 ^o , determine the minimum torque value and then set the crankshaft to this position crank the crankshaft in the opposite direction, applying a torque equal to the moment of resistance to cranking the crankshaft without pistons, and sequentially n-1 times, where n is the number of cylinders engine, increase the torque by the amount necessary to move one piston in the cylinder, and at each value of the torque measure the angle of rotation of the crankshaft, and the gaps are determined by these angles of rotation.