NO145577B - PROCEDURE FOR PREPARING POLYVINYL ACETATE DISPERSIONS - Google Patents

Description

Device for providing a control voltage for regulating the speed of an electric motor.

The present invention relates to a device for providing a control voltage for regulating the rotational speed of an electric motor in relation to the rotational speed of another electric motor, where a change-over contact or a control device for a change-over contact is arranged in connection with each motor's shaft.

When operating a machine, one must often

cooperating machine is operated at a speed which is in a certain relation to the speed of the first machine, e.g. a transporter in relation to a production machine.

The purpose of the invention is to solve

this task in a new and simple way, and it is achieved according to the invention by the change-over contact for the main motor, in one position, connecting a voltage source with a capacitor across a limiting resistor and in the other position connecting

the first capacitor with a second capacitor across the same limiting resistor, and which alternating contact for the following motor in one position connects another voltage source of opposite polarity to a third capacitor across a second limiting resistor and in the other position connects the third capacitor which has the opposite polarity in relation to the second capacitor, with the second capacitor across the second limiting resistor, the control voltage being taken out across the second capacitor.

Preferably, the voltages of the voltage sources are much greater than the control voltage.

The control voltage can be used e.g. to a phase inverter which in turn controls a controlled rectifier which regulates the current to the following motor. The control voltage can also be used to control a transistor that regulates the current to the follower motor.

An embodiment of the invention will be described in more detail below with reference to the drawing, which schematically shows a device according to the invention.

On the main motor's A shaft, a control cam is placed which operates a changeover contact K 1 which, when the control cam rotates, alternately brings the contact Kli into contact with a fixed contact K 2 resp. K 3. The contact K 1 is connected to a capacitor C 1 over a charging or discharge resistance R 1, the second electrode of the capacitor C 1 being connected to the negative terminal of a supply voltage source V 1 whose positive terminal is connected to the contact K 2.

When the contact K 1 is in contact with the contact K 2, the capacitor C 1 will be charged across the resistor R 1, and when the contact K 1 during the rotation of the motor A is brought into contact with the contact K 3, a capacitor C 3, which is connected to the contact K 3 ,. be charged from the capacitor C 1 across the resistor R 1. The second electrode of the capacitor C 3 is connected to the negative electrode of the capacitor C 1. This is repeated until the voltage Vs across the capacitor C 3 is large enough to start the follower motor B.

The follower motor B has a similar contact control device as the main motor A. The changeover contact L 1 which is controlled by the follower motor B is alternately brought into contact with fixed contacts L 2 resp. L 3. The contact L 1 is connected to a capacitor C 2, which is preferably variable, over a charging or discharge resistance R 2, the second electrode of the capacitor C 2 being connected to the connection between the capacitors C 1 and C 3 and to the positive terminal of a voltage source V 2, whose negative terminal is connected to the contact L 2. When the contact L 1 is in contact with the contact L 2, the capacitor C 2 is charged across the resistor R 2, but with the opposite polarity of the charge on the capacitor C 1. When the contact L 1 is brought into contact with the contact L 3, the capacitor C 3 will be drained of part of its voltage.

When the rotational speed of the main motor A increases, the capacitor C 3 is charged and this leads to an increase in the rotational speed of the follower motor B. By varying the capacitor C 2 , the speed of rotation of the follower motor B can be regulated, so that it rotates faster, equal to or slower than the main motor A.

The voltages V 1 and V 2 are preferably chosen to be much larger than the produced control voltage Vs, due to the fact that charge and discharge must be approximately equal, whether the voltage Vs is minimal or maximal.

The device according to the invention can be used in connection with more than two engines, and can be placed between each of these or between the main engine and each of the following engines.

It is clear that the capacitor C 1 can also be made variable and thereby the regulation range can be extended considerably.

Claims (2)

1. Device for providing a control voltage for regulating the speed of an electric motor in relation to the speed of another electric motor, where a change-over contact or a control device for a change-over contact is arranged in connection with each motor's shaft, characterized in that the change-over contact for the main motor, in one position connects a voltage source to a capacitor across a limiting resistor and in the other position connects the first capacitor to a second capacitor across the same limiting resistor, and which alternating contact for the follower motor in one position connects another oppositely polarized voltage source to a third capacitor across a second limiting resistor and in the second position connects the third capacitor, which has the opposite polarity in relation to the second capacitor, with the second capacitor across the second limiting resistor, the control voltage being removed across the second capacitor. 2. Device according to claim 1, characterized in that the voltages of the voltage sources are much greater than the control voltage.