Collector engine - what is it?
Since ancient times, people realized that if you do not want to personally make an effort, then you need to find a replacement. So, carts pulled the horses, donkeys worked at the mills, and the ships were driven by the sea by the wind. But since that time, much water has floated away, and people have even been able to come up with something more modern. And so something modern is the collector engine, which will be discussed. Will be considered varieties, schematic view, methods of adjusting the number of revolutions, as well as the advantages and disadvantages of their operation.
What is called a collector engine?
A collector motor is an electric machine, the rotor position sensor and the current switch in which is the same device, called the brush-collector unit. About the latter, you can tell more. It provides the electrical connection of the chains in the fixed part of the machine with the rotor chains. Structurally, it consists of brushes (by them are meant sliding contacts that are located around the rotating part of the engine) and collector (that is located on a movable element of the mechanism).
The general advantages include the fact that the collector engine is easy to manufacture and operate, has a significant resource of use and can be easily repaired. Common disadvantages include the fact that they have a low mass and high efficiency. In most cases this is only a plus, but not now. Thus, the combination of low mass and speed (which reaches hundreds and thousands of revolutions per minute) leads to the fact that for normal operation, gearboxes are almost always required. And when rebuilding at low speed, the machine has a reduced efficiency, and there are problems with cooling. While an elegant solution to this problem could not be found.
Varieties of the collector engine
There are two main types, each of them has its own advantages and features. Very common and diverse are DC collector motors. Their designs can be divided into the following subtypes:
- The weakest, the working voltage of which is 3-9 Volts, and which are used in children's toys. They have a bipolar stator, in which permanent magnets are installed.The collector assembly is constructed of two brushes, which usually use copper plates. Unlike the stator, the rotor of these engines has three poles. It is installed on the bearings. The power of such mechanisms is measured in several units of watts.
- Medium-sized motors have an operating voltage of 12 or 24 volts. Used in cars, work machines, in ventilation cooling systems. Generate power of several tens of watts. They have a multi-pole rotor, which already works on rolling bearings. The collector knot consists of 4 brushes (as a rule, already graphite). The stator has four poles, but it still consists of permanent magnets.
- There are still engines that can generate power, which amounts to hundreds of watts. The only difference from the construction described in paragraph 2 is that electromagnets are used for the stator.
But besides such representatives there are also universal collector motors. Their peculiarity is that they can operate on both direct and alternating currents. They are used in power tools, household appliances and railway transport in trains driven by electric locomotives.Their prevalence is due to the small size and weight, relatively low price and the ability to easily adjust the number of revolutions. Due to the fact that it is an AC collector motor, it can work with unstable energy sources within reasonable limits.
Schematic view of the collector engine
There is no generally accepted scheme. What you see is just one of the options. The scheme of the collector engine can be built as you want. There are only requirements for what should be within the scope of the working drawing: a stator and a rotor. The AC collector motor must also be fitted with a fuse that will not allow it to burn.
How to regulate the number of revolutions?
Changes are possible if the speed control of the collector engine is used. The difference in the amount of electricity supplied can change their number by only 10 percent, plus or minus. While the speed control of the collector engine allows you to reduce them at times, and you can make it yourself or buy it. And in any case, you need to check whether it can work in the mechanism of such power and such speed (first theoretically, and then in practice).After all, if the regulator is too weak, then failing it will be a trifling matter.
Advantages and disadvantages
Advantages which the collector engine has:
- Small starting current, which is desirable for home appliances.
- Universal motors can be connected to the network directly, without straightening. But this applies only to them. DC motors require rectification.
- Easier to make the control circuit.
- More starting moment.
- Compact design even with the use of the gearbox.
- Unstable power value, which give revolutions of the collector engine when the load changes.
- Relatively low reliability and service life.
- Due to the loss of inductance and the magnetization reversal of the stator, the efficiency may decrease.
Mechanically, the closest is a valve motor. In it the main thing is the inverter, but not brush-collector knot. But a common disadvantage of this design is the lower maximum moment with the same dimensions.