SU1615596A1 - Method and apparatus for testing carburettor engines - Google Patents

Abstract

The invention relates to bench life tests of internal combustion engines. The aim of the invention is to intensify the test by simulating the mode of motor braking on the stand with obtaining alternating torque on the shaft from the action of gas forces. The method consists in that on a stand with a brake machine with synchronous change of the resistance moment on the shaft depending on the engine shaft rotation speed, the crankshaft frequency and the shaft torque vary in the set value range by oscillating movement of the carburetor throttle lever At the same time, at the beginning of the cycle, the control lever smoothly moves in the direction of increasing the supply of the fuel mixture, increasing the frequency of rotation of the engine shaft and the torque on the shaft, then By setting the lever to move progressively upward, it abruptly (abruptly) returns it to its original position, which corresponds to the minimum throttle angle. The device implementing the method comprises an eccentric mechanism with a crank sleeve, which is connected by means of an adjustable rod with a spring-loaded throttle valve control lever for the carburetor of the engine under test. The crank bushing is installed in the half-ring groove of the eccentric disc with the possibility of free sliding along the groove at a predetermined angle of rotation advance of the crank. The device allows adjusting the phase angle of resetting the throttle control lever, as well as changing the range of variation of the supply of the fuel mixture to the engine for each test cycle, keep the angle of rotation crankshaft advance (the angle of free reset of the throttle control lever). 2 sec. and 2 z. p. f-ly. 7 il.

Description

The invention relates to mechanical engineering, in particular to methods for accelerated bench tests of carburetor.

internal combustion engines for reliability with setting loading modes in automatic mode.

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The purpose of the invention is to intensify the tests by simulating the motor braking mode with obtaining an alternating torque.

Figure 1 presents the General scheme of the stand for the implementation of the proposed method; 2 shows a control circuit for a carburetor throttle valve; on fig.Z - device eccentric mechanism (eccentric); figure 4 - node I in fig.Z; figure 5 - the shape of the plate of the eccentric with grooves; figure 6 - the plate shape of the eccentric with a notch; Fig. 7 shows the dependence of the change in torque on the engine shaft when it is tested on the stand.

The device (Fig. 1) contains a brake machine U, an electric motor 2, an eccentric drive gearbox 3, an adjustable eccentric bushing 4, a carburetor throttle actuator cable 5, a cable length adjustment screw 6, a return spring 7, a test engine 8 and an eccentric 9 mounted on the output shaft Yu (fig.Z) gear 3.

The eccentric 9 is made in the form of two mutually adjacent plates 11 and 12 (FIG. 3) and secured with the nut 13 of the spring washer 14, the transition sleeve 15 and the washer 1.6. The plate 12 is equipped with a straight-through 17 and a half-ring 18 grooves, in the latter there is a head of a crank bushing 19 connected by a drive cable 5 with a spring-loaded lever 20. The eccentric 9 is fixed on the shaft 10 of the gearbox 3 with the possibility of adjusting the crank radius. One end of the cable 5 is hinged but connected to the sleeve 4 of the eccentric, and the other end of the cable is hinged to the spring-loaded carburetor throttle control lever 20.

The eccentric 9 is made in the form of two mutually adjacent plates 11 and 12 (Fig. 3) with the ability to move along the plane of contact, and in the plate 12 two ductile grooves are made — one semi-circular 18, the other straight 17 located along the axis of symmetry of the semi-circular groove with its concave side. The plate 11 has a through central hole and a through hole with an angle et et apex (FIG. 3), with the axis of rotation of the shaft 10 of the gearbox 3 located in

0

15

20

25

596

thirty

35

40

45

one of the 13 positions of the recess groove 17 fixed by the nut and the central through hole aligned with it. Adjustable sleeve gi 4 (cable 5) is installed in a half-ring groove 18 with the possibility of free sliding along the groove. The cut sector of the plate 11 faces in the direction of the concave part of the semi-annular groove, and the axis of symmetry of the sector and the cesium coincide. In this case, the edges of the sector of the plate 11 are installed with the possibility of limiting the length of the semiring groove 18 at both ends.

The method is carried out as follows.

Prepared for testing engine mounted on the stand. Brakes, gauges, power systems, lubricants and engine cooling are connected. The lever 20 for controlling the throttle valve of the carburetor is connected by means of a flexible rod (cable 5) with a mechanism for the continuous opening and closing of the throttle valve of the carburetor (gear 3).

The engine is warmed up to the operating thermal state. Specified loading mode is provided by moving the carburetor throttle. The duration of each test cycle (the time of one full turn of the eccentric) is 35-40 seconds. At the same time, the engine operates in continuously variable speed and load modes: during one cycle, the crankshaft speed first increases from ly to 0.75 pce and the engine load from zero (at) TO -100% (at 0.75 n) and then decreases to the original values.

The method is based on the fact that when the engine is running on a stand with a braking machine that can synchronously change the braking torque on the drive shaft depending on the shaft rotation speed, the speed and load modes are changed in the set value range by oscillating the movement of the carburetor throttle control lever in automatic mode.

At the beginning of the cycle, with a low rotational speed of the crankshaft and a minimum braking torque on the drive shaft, the fuel supply is gradually increased.

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in the engine, increasing the frequency of rotation of the shaft, the braking torque on the shaft of the drive; and and, accordingly, the engine torque. Then, not stopping the forward movement of the fuel lever in the direction of increasing, abruptly (abruptly) shifting it to the initial position, corresponding to the minimum angle of opening of the carburetor throttle valve.

At the same time, due to the high angular velocity and the angular acceleration of the rotating masses positively directed during the period of smooth acceleration, the inertial moment of resistance of the rotating masses and the braking torque of the drive, reduced to the crankshaft, have the highest values. The absolute magnitude of their torque from the action of gas forces from its maximum value drops sharply to zero and changes its sign to the opposite due to throttling the flow of the fuel mixture supplied to the engine and the torque generated. inertial rotation of the flywheel of the engine and drive machine.

A device for carrying out the proposed method works as follows.

Set the required range of cyclical adjustment of the fuel supply to the engine (Fig. 2) by loosening the nut 13, adjusting :: the required radius of the crankcase OA and fastening the nut 13. the minimum frequency of idling (in the position when point A is in the continuation of the AB string on the same straight line with the center O). The device is ready for operation,

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After the engine has been prepared for sensing the load on the stand and the magnitude of the load of the brake train has been adjusted at nominal: 1 to the rotation frequency of the motor shaft, the electric motor 2, gearbox 3 adjusted to a certain frequency of rotation of the output shaft are turned on. The sleeve 19 of the crank, by the I-Ia walls of the semi-ring groove 18 and bounding the sector, moves around a circle of radius r, smoothly moving the lever, 20

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control throttle carburetor. At the same time, the frequency of rotation and the torque on the engine shaft increase smoothly and synchronously. Then, reaching point A on the diagram, corresponding to the sliding angle of the Crank bushing along the semi-circular groove 18 (and, phase reset angle, Q is controlled by the vertical movement of the gearbox 3 along its direction ™ by the amount h), the fuel supply lever 20 under the action of return the springs abruptly return to their original position due to the free sliding of the sleeve 19 along the groove 18.

The advance angle corresponds to the yrnv of the excised sector plus the increment arising due to the angular velocity 63 directed towards the free slip. When the radius of the crank crank OA changes, the range for fuel supply (angle CG) 5 changes accordingly. 5 The length of the semiring groove 18 decreases or increases with the preset angle (Fig-D.2). Experimentally established the preferred shape and 0 optimal dimensions of the eccentric mechanism. The semi-circular groove is made in the form of a parabola, described by the equation

)five

20

35

X

y -

20 Such a slot operation allows

40

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at different radii of the eccentric, increase the uniformity of the sleeve of the crank 19 along the groove in the position corresponding to the minimum feed (trajectory of point A when choosing the free stroke of the sleeve along the groove), which eliminates the deviation of the minimum rotational speed of idling from the set value testing program .

The collar groove is made along the symmetry axis of the parabola, starting from the point F of the parabola focus on the length n of the parabola (0 CP) (10 mm), and the angle of the cut sec. ° When performing the angle 0 J50, the amount of free release of the lever; The control of fuel supply to the engine is insufficient, 5 which affects the amplitude of the change in the torque on the shaft in the direction of its reduction. The angle 0 170 is impractical due to the fact that almost all

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The lever retraction is selected with respect to the increment arising due to the angular velocity of the rotating eccentric.

Example. A capitally repaired engine brand ZMZ-53,; P) osh; a rim ten-hour technology run-in, set to: a tendency, connect the electric brake machine KI-5543, the power supply system, the cooling system and the lubricant. Preheat engine to cool water temperature.

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- and oils t) j 85 C. The braking moment is set by deepening the rheostatic knives of the rolling stand to the readings on the dial of the force-measuring mechanism p. 25 kg (MKR 18 kg) at a frequency of rotation of the shaft n 2400 r / min

A low eccentric mechanism connects the carburetor throttle control lever to the eccentric sleeve. Set the range. adjusting the amount of fuel supply by changing the frequency of rotation of the shaft 1500 - 2400 with a synchronous change of the load from 0 (at 1500 ° C to 25 kg (at 2400). At that, the gearmotor shaft with the eccentric mechanism installed on it co-ordinates one full turn.

Noting the start time of the tests p: mode, turn on the gear motor with i output rotation frequency I 0.1 s. Temperature-mode is supported. live throughout the whole time: the trials. In the test mode, the engine worked for 42 hours. As a result, a failure occurred — a failure of the middle clutch disc. The engine did not stand the test.

The method makes it possible to increase the efficiency of life tests of automobile engines by obtaining, during each test cycle, the alternating torque on the crankshaft from the action of gaseous forces using the torque of the engine rotating masses.

Claims (4)

driving machine. Formula invented the shadows 1 Method of testing a carburetor engine on a stand with synchronous change of the braking torque on the engine shaft depending on the frequency of rotation of the shaft, which means that in automatic mode eight in the established range of values, the frequency of rotation of the engine shaft and its torque by changing the supply of the fuel mixture by changing the carburetor throttle valve, characterized in five thirty Q one . v - - - tici- that, in order to intensify the tests by simulating the motor braking mode with obtaining an alternating torque on the shaft, the carburetor throttle valve is first gently moved in the direction of increasing the flow of the fuel mixture, then, without stopping the displacement, sharply (abruptly) move its initial position corresponding to the minimum. stable idle speed. 2. The method according to claim 1, which differs from the fact that the frequency of test cycles is set in the range of 0.005 ... ... O 2 Hz, and the rotational speed of the motor shaft is in the range of the minimum stable rotational speed of the holos-. that turn to the nominal speed, the torque of the motor shaft being changed in the range (-0.30 ...- AND, 0) of its nominal torque value. 3. A device for testing engine bureaus engine, containing a gear motor, an eccentric mounted on its wapa, with the possibility to adjust the crank radius, and adjustable along the length of the thru, with one end of the thrust hinged to the eccentric bushing, and the other hinged with a spring-loaded throttle turn lever, characterized in that, in order to intensify the test by simulating the motor braking mode on the stand, the eccentric is made in the form of two mutually adjacent plates with the ability to move They are tangentially connected, with one plate provided with two through -pipes — a semi-circular and rectangular, horizontally located on the concave side of the semi-circular groove along its axis of symmetry; the other plate1 is provided with a central through square hole and 55 through-cut in the form of a sector, with an angle at the vertex, and the edges the sectors are configured to limit the length of the half ring 40 45 50 at both ends, the cutout faces the concave part of the plunger groove and the axis of symmetry of the sector and the groove coincide; 15596 .10 4. A device according to claim 3, characterized in that the angle of the skozny sector is oL 150- ... 170, the semiring groove is made in the form of a parabola, described by the equation at X / 20, and the rectangular groove is made at a length of 1 p from the point focus of the parabola, where j) is the parameter of the parabola. 5 6 1  fi FIG. g FIG. M, K // - AT Fy