RU2430340C2 - Method of defining vehicle effective power output in taking-off - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: vehicle and tractor with dynamopraph or dynamometre are prepared to joint vehicle to tractor to measure maximum tractive force in taking off. Thereafter, vehicle rated tractive power is calculated by formula.

EFFECT: simplified method, shorter procedure.

1 dwg

Description

The invention relates to testing and technical diagnosis of machines, in particular to a method for determining the rated traction power of a transport vehicle (mainly a tractor). In addition, it can be used in mechanical engineering for the production of vehicles and their engines from production.

A known method for determining the effective power of an internal combustion engine based on measuring the angular acceleration of the crankshaft in the free acceleration mode [1].

The disadvantage of this method is that for its practical implementation requires a complex electronic device IMD-C. In addition, the engine must have a special hole in the flywheel housing for installing the primary speed converter.

The closest technical solution, selected as a prototype, is a method for determining the maximum traction force on the hook of a transport vehicle in the traction mode of pulling away [2].

The disadvantage of this method is that it allows you to determine only the maximum traction on the hook of the transport machine.

The objective of the invention is to provide a method that allows you to determine the nominal effective power of the engine of the machine during traction tests in the mode of pulling away.

The invention consists in the following. According to the results of measuring the maximum traction force, the rated effective engine power of the transport machine is determined. In this case, the coefficient of correspondence of the maximum traction force to its value at the inflection point on the graph of traction power is taken into account as a function of the traction force, the efficiency of the transmission of the transport machine, the efficiency of the brake system, and the angle of inclination of the direct regulatory branch of the traction characteristic to the abscissa axis. As a result, it seems possible to determine simply (without the use of sophisticated equipment) and quickly (within 3-5 minutes) the rated effective engine power of the transport vehicle.

The drawing shows a method for determining the effective engine power of a transport machine when it is tested in the traction mode of pulling away.

We show the practical possibility of implementing this method.

At the first stage, we find a mathematical description of the tractor's traction power by the traction characteristic.

Suppose that when testing a working tractor in the starting mode, a reference dependence of the traction power on the traction force is obtained (see drawing) - N _t = f (P _t ). In this case, the power graph is represented by the curved line of the OAB, one part of which OA is the regulatory branch, and the other AB is the corrective branch. We write the OAB triangle in the power graph so that point O coincides with the origin, point A corresponds to the nominal value of the traction force P _tn and the nominal traction power N _tn , and point B corresponds to the maximum traction force P _{t max (N)} , as shown in drawing. From points A and B, lower the perpendiculars to the abscissa: AP _tn and BP _{t max (H)} . Let also, after some time, the tractor turned out to be faulty - its traction power does not correspond to the established tolerance for its reduction. When testing a faulty tractor in the same mode and using the same traction device (under identical conditions), a real dependence N _t = f (P _t ) is obtained, which is described by the curved line OA ₁ B ₁ . In this graph, we write the triangle OA ₁ B ₁ in the same way and from the points A ₁ and B ₁ we also lower the perpendiculars to the abscissa axis: A ₁ P _{tn (I)} and B ₁ P _{t max (I)} , where R _{tn (I)} and P _{t max (I)} is the nominal and maximum value of the traction force obtained during the test.

From the drawing it is easy to see that all the triangles related to the line OAV, similar to the corresponding triangles of the line OA ₁ In ₁ . It is known that if triangles (flat figures) are similar, then their respective sides are proportional. Based on this, we have (see drawing)

where γ _T is the coefficient of correspondence (proportionality) of the maximum thrust force to its value at the inflection point on the graph of the function N _t = f (P _t ). It should be noted that the coefficient γ _t in its physical sense is the closest to the known coefficient of adaptability of the engine

where M _emax , M _en - the maximum and rated engine torque.

Also from the drawing in general terms, we have the following description of the function of the tractor's nominal traction power:

where α is the angle of inclination of the conditional direct regulatory branch of the traction characteristic (direct OA) to the abscissa axis.

For an intermediate value of traction power N _T (in the range from 0 to N _TH ), equation (2) can be rewritten as follows:

where P _T is an intermediate value of the traction force corresponding to N _T.

Express P _T from (1) -

where P _Tmax corresponds to P _{Tmax (I)} .

We substitute Р _Т (4) in (3) and take into account the efficiency of the brake installation η _TY . As a result, we obtain the desired mathematical description of the rated traction power when testing the machine in the starting mode

Now we find a mathematical description of the effective engine power from the expression (Ferry N.E. Manual for the operation of the machine and tractor fleet / N.E.Fere. - M .: Kolos, 1978. - P. 25) - for the traction unit (without drive through PTO):

where N _e is the effective engine power; N _POT - power loss during the transfer of energy from the engine to traction. Wherein

where N _M - mechanical power loss in the transmission, including friction losses in the links of the tracks; N _f , N _α , N _δ - power losses due to tractor movement (rolling), to overcoming the rise and to slipping. For traction tests in the mode of starting the car from a place:

N _f = 0; N _α = 0; N _δ = 0.

Then equation (7) takes the form:

N _POT = N _m

or when N _M = N _e (1-η _m ) -

where η _m - mechanical efficiency transmissions.

We substitute (8) into the original equation (6) and after the transformations we obtain

From - from (9)

We will present the found equation (10) with allowance for (5). After that, the mathematical description of the effective engine power will take the following final form:

Thus, in order to practically determine N _eH, it is necessary to measure Р _Tmax in the traction mode of pulling the machine away and calculate N _eH according to formula (11) for constant and known values of γ _t , η _m , η _TY and tgα. When measuring P _Tmax perform the following operations. A vehicle and traction device with a dynamometer or dynamometer are prepared for testing. Attach the machine to the traction device. The measurement of the maximum traction force P _{Tmax is} carried out by a dynamograph or dynamometer in the mode of moving the machine from its place.

INFORMATION SOURCES

1. Workshop on the operation of the machine and tractor fleet / V.A.Alliluyev, A.D. Ananyin, A.X. Morozov. - M .: Agropromizdat, 1987, S.22-30.

2. RF patent No. 2164670, 7 G01L 5/13, 07/31/96. - prototype.

Claims (1)

A method for determining the effective engine power of a transport machine when it is tested in the traction mode of pulling away from the place where the transport machine and the traction device with a dynamometer or dynamometer are prepared for testing, attach the machine to the traction device and measure the maximum traction force in the mode of moving the car from the place, different the fact that according to the results of measuring the maximum traction force determine the nominal effective engine power of the transport machine, while taking into account the coefficient of compliance ma the maximum traction force to its value at the inflection point on the graph of traction power as a function of traction force, the efficiency of the transmission of the transport machine, the efficiency of the brake system, and the angle of inclination of the direct regulatory branch of the traction characteristic to the abscissa axis.

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