Real scheme

EM – electric motor;

C1,C2 – connecting clutches;

R – reducer;

D – drum;

L – load;

H – hook;

R – robe.

The electric motor EM through connecting clutch C1, reducer R, clutch C2 rotates the drum D, on which the robe R is wounded.

The end of a robe R is connected with a hook H (actuating mechanism), on which the load L of mass m is lifted.

The ED load is defined by the effect of weight force and also by friction of movable parts. The later character of a load has the name of losses because of friction and reduction gear and drum efficiency are to be considered.

As a result of reduction of all this moments of inertia, masses and pulling forces, that are found in above real scheme of ED it will get the equivalent computational scheme to the electric motor shaft

Figure 2.3 – Reducing computational scheme

where it is necessary to determine reduced value of moment of load Mc (static moment of resistance) and reduced value of inertia moment J. It is realized in the following way.

Reduction of load moment is realized coming from equality of load power of a motor in real and in equivalent (reducing computational) schemes.

For the case of load lifting the motor is make useful work of load lifting and covers the power losses on friction in kinematic link. The energy is directed from the motor to actuator mechanism, and energy balance in this case has such a view

,

where from

[Н∙м],

where – reduced to motor shaft load moment (static moment of resistance), [N ^. м];

– angular velocity of motor shaft [];

- weight force, [N];

- linear velocity of load lifting, [m/s];

- reduced radius, [m];

- load mass, [kg].

Reducing of inertia moments and elements mass is realized coming from equality of the kinetic energy storage in real and equivalent (reduced computational) schemes.

,

where from

,

or

,

where - reduced inertia moment to motor shaft MTD, [kg^.m²];

- inertia moment of a motor, clutch C1 and gear Z1, [kg^.m²];

- inertia moment of a drum, clutch C2 and gear Z2, [kg^.m²].

So, to reduce inertia moment of rotating element to the motor shaft it is necessary to divide its inertia moment to the square of reduction gear ratio of kinematic chain area between motor and this element.

To reduce the element mass, that moves translatory it is necessary to multiply its mass by reduced square radius of kinematic chain area between motor and this element.

Дата добавления: 2014-01-05