RU2476840C1 - Method of determination of gas forces torque moment - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: drive shaft is secured rotationally by means of brake with constant brake torque, gas pressure is created in volumetric machine, moment of external forces, effective against gas forces moment, is applied to the shaft of volumetric machine and is increased until the shaft is moved. Then value of force applied to the shaft in the moment start of volumetric machine movement is measured, and external forces moment is applied in opposite direction and is increased until the shaft starts moving, also value of force in the moment of movement start is measured, and gas forces torque moment is determined as a product of difference of measured values and half-arm of external force application.

EFFECT: improving accuracy of determination of torque moment by means of consideration of losses caused by friction in mechanical units of volumetric machine.

2 dwg

Description

The invention relates to compressor engineering and can be used to determine the torque from gas forces in volumetric machines.

Known methods for determining the torque of machines and mechanisms in which the drive shaft is kept from rotating by the brake and determine the total torque averaged over the angle of rotation of the machine shaft of the machine (RU 2052775 C1, publ. 20.01.1996).

The disadvantage of this method is the inability to determine the contribution of various factors in the formation of the magnitude of the torque, in particular friction losses.

Closest to the proposed is a method for determining the torque in a volumetric machine, which consists in first measuring the torque M ₁ on the shaft with a load. Then measured the torque M ₂ on the shaft of the machine without load. In both cases, the torque is determined by measuring the instantaneous magnitude of the current drawn by the electric motor. To accurately determine the torque, the difference (M ₁ -M ₂ ) is calculated (JP 2000145667, publ. 26.05.2005). This method allows you to determine the dependence of torque on the angle of rotation of the shaft, and also take into account friction losses in the compressor drive.

The disadvantage of this method is that it does not allow to take into account friction losses in the mechanical components of a volumetric machine.

The technical result is to increase the accuracy of determining torque by taking into account friction losses in the mechanical components of a volumetric machine.

The technical result of the invention is achieved due to the fact that in the method for determining the torque from gas forces in a volumetric machine, which consists in holding the drive shaft from rotation by means of a brake with a constant braking torque, gas pressure is created in the volumetric machine, applied to the volumetric shaft machines the moment of external forces acting against the moment of gas forces, and increase it until the shaft is stationary, measure the force applied to the shaft at the time of moving the volumetric machine, then butt vayut moment of external forces in the opposite direction and increase it until the shaft breaks free from the space, as measured by the amount of force in starting torque, and torque from the gas forces is determined as the product of the difference of the measured values and the half shoulder application of external force.

The moment of gas forces M _gf is expressed through the forces F ₊ and F _- as follows:

M ₊ + M _gf = M _Tr and M _- -M _gf = M _Tr , which means

M _gf = (M _- -M ₊ ) / 2,

but M _- = F _- * r and M ₊ = F ₊ * r.

Hence, M _rc = (F _{- +} F) * r / 2, where

M _Tr - moment of rest friction;

M _gs - the moment of gas forces;

M ₊ is the moment from an external force applied in the direction of action of M _gf ;

M _- - moment from an external force applied against the action of M _gf ;

F ₊ is the external force creating the moment M ₊ ;

r is the shoulder of the application of external force;

F _- is the external force creating the moment M ₊ .

The determination of the torque from the gas forces is repeated for various angular positions of the drive shaft of the volumetric machine. The result is a dependence of torque on gas forces on the angle of rotation of the shaft, not distorted by the influence of friction in the mechanical components of the machine.

The invention is illustrated by drawings, where:

- figure 1 (a) schematically shows an experimental stand (top view);

- figure 1 (b) schematically shows an experimental stand (front view);

- figure 2 schematically shows a fragment of an experimental stand (section AA in figure 1 (a)).

In the drawings are indicated:

1 - rack;

2 - dynamometer;

3 - brake pads;

4 - hairpins;

5 - steel elastic bracket;

6 - discharge fitting;

7 - spiral machine;

8 - thrust;

9 - mounting table;

10 - device "bolt-nut";

11 - holes;

12 - bracket;

13, 14 - screws;

15 - steel pulley:

16 - threaded holes.

The method of determining the torque is as follows.

The spiral machine 7 of the experimental bench (Fig. 1 (a), (b)) is secured by a flange using bolts on the rack 1, which is installed on the mounting table 9. The discharge nozzle 6 of the spiral machine 7 is connected to the compressed air network using rubber hoses (on drawings not shown). The pressure of the supplied air is measured using a pressure gauge and is regulated by a control valve (not shown in the drawings).

A steel pulley 15 is rigidly mounted on the shaft of the spiral machine 7. It is made stepped and has a side surface of variable diameter. On the side surface of a smaller diameter with equal pitch, holes 16 are made with threads, into which, depending on the position of the pulley 15, a screw 14 is alternately screwed to secure the rod 8, which is used to exert external force. Holes 11 are made on one generatrix with holes 16 at an equal distance from them. On the rack wall 1, a bracket 12 is installed, having a through hole with a thread into which a screw 13 is screwed, which together with the holes 11 allows the shaft of the spiral machine 7 to be accurately positioned by the angle of rotation. The side surface of the larger diameter of the pulley 15 is ground. Brake pads 3 are adjacent to the side surface of a larger pulley 15 along the braking surface. Brake pads 3 are made of a composite material with high friction properties and are fixed on a steel elastic bracket 5. The bracket 5 is fixed to the mounting table 9. The bracket 5 with the brake pads 3 is pulled together with pins 4, which allows you to press the pads 3 to the side surface of the pulley 15 with a certain braking force.

On both sides of the brake on the rack wall symmetrically install two tensioning device 10 "bolt-nut". By rotating the bolt 10, an external force is applied, which in turn creates a torque. Between the bolt 10 and the rod 8 of the application of an external force to measure this force, a dynamometer 2 is installed.

A brake is mounted on the shaft of the volumetric machine with the possibility of adjusting the braking force and a stable coefficient of friction. Compressed air is supplied to the injection machine of the volumetric machine, while the shaft of the machine is kept from rotation by a brake with a constant braking force. Then, on the arm r, a force is applied to the shaft of the volumetric machine through the dynamometer 2, which creates a torque that coincides in direction with the moment of gas forces M _g . This external force is gradually increased until the shaft of the volumetric machine begins to rotate. The force applied to the shaft at the time of its breaking F ₊ is measured. Then, without changing the braking force, at the same pressure of the air supplied to pump the volumetric machine and at the same angular position of the shaft on the shoulder r, an external force is applied to the shaft in the opposite direction. This force is also gradually increased until stragging occurs. At this moment, the force F _{- is} measured.

The moment of gas forces is determined by the expression:

M _gf = (F _- -F ₊ ) r / 2

Claims (1)

A method for determining the torque from gas forces in a volumetric machine, which consists in holding the drive shaft from rotation by means of a brake with a constant braking torque, creating gas pressure in the volumetric machine, applying external forces to the shaft of the volumetric machine acting against the moment of gas forces , and increase it until the shaft is stationary, measure the force applied to the shaft at the time of moving the volumetric machine, then apply the moment of external forces in the opposite direction and increase ie it until the shaft breaks free from the space, as measured by the amount of force in starting torque, and torque from the gas forces is determined as the product of the difference of the measured values and the half shoulder application of external force.

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