Electromagnetic powder brakes minimum temperature. Powder couplings. Hysteresis coupling. Safety elements, electromagnetic friction multi-plate clutches

3 037 filled with ferromagnetic powder, housing and rotor with magnetic conductors, which have longitudinal grooves increasing the volume of the working element f2: . This coupling is closest to the invention in terms of technical essence and achieved result. This design of the coupling solves very well. the question of increasing the transmitted torque by increasing the amount of ferromagnetic powder. Moreover, the third increase in the amount of the latter does not affect the idle operation of the clutch. Specified positive traits This is ensured by making grooves on the working surfaces of the magnetic cores running parallel to the coupling axis. However, in order to achieve an increase in torque ms by 2-3 times, it is necessary to increase the amount of ferromagnetic powder by more than 4 times. Such an increase requires either deep or wide grooves. Deep grooves are clearly ineffective, since tightening is difficult

f and the formation of full-fledged ligaments that transmit torque. The inefficiency also lies in the fact that it is desirable to direct the magnetic flux completely through the working gaps, and not dissipate it along the magnetic core. In the case of wide grooves, the working surface area of the magnetic cores is not enough to form bundles, i.e. the entire poured amount of powder. As a result, the described coupling design has a slipping value of the coupling halves of 35-40 cm/at

35 transmitted moments of more than 1200 kg/cm. As a result of this amount of slipping, the temperature during this period increases by 25 C. This phenomenon negatively affects the property of the magnetic permeability of the working surfaces of the coupling, which, as is known, are made of soft magnetic material and are sensitive to every degree temperature rise.

The purpose of the invention is to reduce

45 slip and increase magnetic permeability.

For this purpose, additional cavities and radial through slots are made in the side walls of the longitudinal grooves, connecting these cavities with the annular cavity of the coupling filled with powder. In Fig. 1 shows an electromagnetic powder coupling, longitudinal section, Fig. 2 - section AA in Fig. l; in fig. 3 - working surface of the magnetic circuit.

The electromagnetic powder coupling contains concentrically located couplings with an operating gap forming a cavity. .. yuluubufta 2 and 3, the first of them is driven, it is designed to transmit torque through gear 4, installed on the annular surface 5 of its housing 6. In the covers 7 and 8 of the latter, bearings 9 and 10 are mounted. The second half-coupling 3 - driving is a drive shaft 11 installed in bearings 9 and 10 and driven from the primary engine. The rotor is located on the latter

12, in the annular groove of which the excitation winding 13 is fixed. The working parts of the coupling halves are made of soft magnetic material and represent magnetic cores 14. These magnetic cores 14 have longitudinal grooves 15 filled with ferromagnetic powder and additional cavities 16. The latter increase the volume of the powder container and are connected radial through slots 17 with annular cavity 1. Through slots 17 are designed for free exit of powder onto the working surfaces of 18 magnetic cores and for uniform distribution of powder throughout the entire free volume of the annular cavity 1.

The electromagnetic powder clutch works as follows. Drive shaft

11„ IIPIIIIOIIHMII I 0 P IIIeHIIe IIe II HI,I the paagator, rotating in bearings 9 and 10, drags rotor 12 into rotation. In the absence of control current, ferromagnetic powder with the help of additional cavities

16 and slots 17 are evenly distributed over the annular cavity l and the longitudinal groove 15. From the latter, during rotation, the excess part of the powder moves into additional cavities 16. When current is supplied to the excitation winding 12, a magnetic flux arises in the magnetic circuit 14. Its power lines pass along the coupling half 2 through the layer of powder, along the coupling half

3 and again through the layer into half-coupling 2, delighting the closed circuit. At the same time, the ferromagnetic powder located in the grooves 15 and cavities 16 is drawn through the slots

17 onto the working surfaces 18 of the magnetic cores 14. The powder that arrives on the working surfaces “hardens”, engaging with the coupling half 2. As a result of the clutch, the gear 4 rotates at an angular velocity, consistent with the rotation speed of the drive shaft.

Making cavities and through slots on the magnetic cores provides an increase work surface magnetic cores up to

30%, which contributes to the formation of strong bonds from the entire poured amount of powder, and an increase in the speed of formation

Reese. 1 bundles due to the directional and uniform distribution of ferromagnetic powder on the working surface.

These factors ensure a reduction in the relative slippage time of the coupling half by 4.5 times, which, together with a more uniform distribution of powder during idle speed

10 reduces heat generation by more than

2.5 times. Reducing heat generation helps to increase both the properties of the magnetic permeability of the magnetic core material and the service life of the ferromagnetic 1 powder.

Claim

Electromagnetic powder coupling according to the author. St., No. 332263, the main difference is that, in order to reduce sliding and increase magnetic permeability, additional cavities and radial through slots are made in the side walls of the longitudinal grooves, connecting these cavities with the annular coupling cavity filled with powder.

Sources of information taken into account during the examination:

1. G1atetst of France I. 1231768 class R 16 3 37/02, 1960.

An important element different designs can be called coupling. Modern technological capabilities have made it possible to obtain more complex devices that are characterized by more attractive performance characteristics. Electromagnetic couplings can be called a modern proposal. They are installed on modern cars and many other devices. The rather complex design and complex operating principle determines that you need to clearly understand such a device to ensure its quality service. Let's look at all the features this issue more details.

What is an electric coupling?

An electromagnetic clutch is a special device for solving a wide variety of problems, most of which involve connecting and disconnecting a pair in mesh. Electromagnetic couplings are produced for machine tools and other components of vehicles or diesel locomotives. There are several main types of such structures:

Friction type mechanisms are cone and disk.
Electromagnetic clutch gear type is considered a specific design option, since the working part is represented by a combination of different teeth.
Powder electromagnetic clutch is a modern design as it provides axial movement when required.

Electro coupling is intermediate connecting element. The principle of operation is to use the basic properties electric current to generate electromotive force.

At the same time, he can perform the most various functions, for example, protecting the main device from overheating or control.

The operating principle of the electromagnetic clutch

The electromagnetic clutch can have the most different designs, but also highlight classic version execution. Its features are as follows:

The main elements can be called two rotors, one of which is represented by an iron disk with a thin end protrusion.
The internal part is equipped with pole pieces that provide radial movement. To transmit current, a winding is created and connected to the power source through slip rings. Part of this element is located on the shaft.
The magnetic coupling under consideration has a second rotor, which is represented by a cylindrical shaft with special grooves located parallel to the main axis. They are created so that special bars with pole pieces can be inserted.

The coupling in question is on permanent magnets has a rather complex design, which ensures accurate and reliable operation. The operating principle of the device is as follows:

When current appears, an electromagnetic field arises, which intersects with the conductor and begins to interact.
Such a combination causes the emergence of electromotive force. It may be quite sufficient to move the moving element, taking into account overcoming a certain force.
In the manufacture of this part, a copper bar is used, which ensures the closure of the circuit. A current passes through them, due to which an electromagnetic force appears.
The resulting fields ensure that the driven rotor follows the leading one, while the delay is insignificant.

A similar operating principle is used to create a wide variety of mechanisms. In this case, the device of the machine makes it possible to stop the transmission of torque within a few fractions of a second, which determines its distribution.

Demagnetization of the electromagnetic clutch occurs by disconnecting the power source. In this case, the special properties of the material determine that the magnetic field disappears almost immediately, due to which the reverse movement of the moving element occurs. The electromagnet windings used are designed for sufficient a large number of This is the coupling and disengagement of the driving element with the driven element.

When considering what an electromagnetic clutch is, you also need to pay attention to the properties of the materials used in its manufacture.

Only special alloys have magnetic properties that provide the required operating conditions.

The transmission of torque to the clutch can be carried out from electric motor and other similar elements. The dimensions of all dimensions are in most cases standardized, but it is possible to order the production of the mechanism to order. Classification is usually carried out according to the area of application and many other characteristics.

Classification of electric couplings

In most cases, electrofusion couplings are classified according to the area in which they are used. The most commonly used electromagnetic friction clutch. It has the following properties:

The device can be used to reduce the likelihood of exposure to impulse loads.
Idling design features identify minor losses. This point determines that the main elements do not heat up during operation.
It is possible to quickly start the mechanism even if it is under heavy load.

The type of mechanism under consideration is divided into several main types:

Contact.
Brake.
Contactless.

Quite often there is an electromagnetic brake clutch, which can reduce the number of revolutions during operation.

Most common last type mechanism. However, it is also classified into several main types:

According to the friction indicator, wet and dry are distinguished. IN Lately Versions that can only work with the addition of oil have become widespread.
Classification is also carried out according to the switching mode: non-permanent and constant.
There are couplings with one or more driven discs. The choice is made depending on the required performance characteristics.
Based on the type of control, there are also several main types of mechanism. An example is mechanical, hydraulic and combined.

Electromagnetic powder couplings are included in a separate group. They are represented by a combination of substances that, when interacting, can provide a strong bond.

This modern version execution occurs in the case when it is necessary to ensure the displacement of the connected elements relative to each other at the time of operation.

Safety elements, electromagnetic friction multi-plate clutches

Such an electric coupling is most often installed on machines with a numerical control unit. The advantages include the following points:

Compactness. Due to this, it is possible to install the electromagnetic coupling in modern devices. Every year the dimensions of the device are significantly reduced, thereby expanding the scope of application.
Reliability. This parameter is considered the most important when choosing almost any coupling. Application special materials and quality control at all stages of production allows us to achieve the highest level of reliability.
Small size. This parameter determines ease of transportation and many other positive parameters.

This version is characterized by fairly high performance characteristics, due to which it has become widespread. The main parts of the structure are:

Frame. In most cases, it is made using steel, which is characterized increased stability to influence environment. The purpose of the case is to protect the internal elements.
Coil. This element is designed to directly create an electromagnetic field, due to which the main elements are displaced. The coil is designed to withstand a certain electrical current, too high voltage has a negative impact.
Friction type disc group. When manufacturing a package of friction discs, a special alloy is used, characterized by certain magnetic properties.
Leash and pressure plate.
The body has a mounted ring made of insulating material.
The current is supplied using a contact brush. It is this that in most cases fails during the operation of the mechanism.

Eliminate the possibility of occurrence short circuit possible using cut holes in the disks. At the moment the electric current is applied, an electromagnetic field is created, which is closed using a friction disk. It is due to this that an attractive force is created, behind which the main part is displaced.

There are several variants of such designs. An example is a device with a remote and magnetically conductive disk.

Advantages of connections using electrofusion couplings

The device in question has become very widespread. This can be attributed to the fact that it has enough big amount benefits that must be taken into account. The following are considered the most important:

Reliability. When electrical current is applied, the device disconnects individual elements within a short period of time. In this case, the electromagnetic field is not affected by the environment, so, as a rule, significant problems during operation do not arise.
Preservation of basic properties over a long period. An important criterion The choice of such devices can be called precisely the operational life. Due to the use of special materials, this indicator in the case under consideration is significantly expanded.
Operation within a few fractions of seconds. This result is typical for a relatively small number of devices in this category. Response time is a parameter that is taken into account when choosing a coupling.
Possibility of execution to achieve a variety of purposes, for example, device protection or remote control.
Compact and light weight. These parameters are also considered quite important, since too much weight puts a strain on the main structure. Its compactness allows the device to be integrated into a wide variety of designs.

However there are several significant shortcomings, which must be taken into account. An example is that the device is quite expensive, and maintenance should be carried out exclusively by a specialist. In addition, operation if basic recommendations are not followed can cause increased wear. Do not forget that the device requires electric current to operate, which causes the appearance of the required electromagnetic field.

Application area

The device has received very wide use, as it provides the connection of several elements and their separation if necessary. The scope is as follows:

Cars and others vehicles have units that are equipped with an electromagnetic coupling.
Recently, the device is increasingly being installed in CNC machines. This is due to the fact that their work requires high precision work.
Several types of different devices have been developed that can act as an intermediate element. Couplings can be used to achieve a variety of purposes, for example, protecting the device from overheating by turning off the drive when the sensor is triggered.

In general, we can say that the use of electric current to generate a signal can significantly expand the scope of application of the device. This is due to the possibility of transmitting signals from various sensors.

In conclusion, we note that electromagnetic couplings produce the most various organizations. It is recommended to pay attention exclusively to products famous manufacturers, since the declared parameters correspond to the real ones. In production, the most various materials, attention is paid to protection from environmental influences.

The electromagnetic clutch is similar in principle to asynchronous motor, at the same time differing from it in that the magnetic flux in it will not be created three-phase system, and excited DC rotating poles.

Electromagnetic clutches are used to close and open kinematic chains without stopping rotation, for example in gearboxes and gearboxes, as well as for starting, reversing and braking machine tool drives. The use of couplings makes it possible to separate the start-up of motors and mechanisms, reduce the time of starting current, eliminate shocks in both electric motors and mechanical transmissions, ensure smooth acceleration, eliminate overloads, slippage, etc. A sharp reduction in starting losses in motors removes the limitation on the permissible number of starts, which is very important during cyclic operation of the engine.

The electromagnetic clutch is an individual speed controller and represents electric car, which serves to transmit torque from the drive shaft to the driven shaft using an electromagnetic field, and consists of two main rotating parts: an armature (in most cases it is a massive body) and an inductor with an excitation winding. The armature and the inductor are not mechanically rigidly connected to each other. As a rule, the armature is connected to the drive motor, and the inductor is connected to the working machine.

When the drive motor rotates the drive shaft of the coupling, in the absence of current in the field winding, the inductor, and along with it the driven shaft, remain motionless. When direct current is supplied to the excitation winding, a magnetic flux appears in the magnetic circuit of the coupling (inductor - air gap-armature). When the armature rotates relative to the inductor, an emf is induced in the first and a current arises, the interaction of which with magnetic field the air gap causes the appearance of electromagnetic torque.

Electromagnetic induction couplings can be divided according to the following characteristics:

according to the torque principle (asynchronous and synchronous);

by the nature of the distribution of magnetic induction in the air gap;

according to the design of the armature (with a massive armature and with an armature having a squirrel cage type winding);

by the method of supplying power to the excitation winding; by cooling method.

The most widespread are armored and inductor type couplings due to their simplicity of design. Such couplings consist mainly of a gear inductor with an excitation winding mounted on one shaft with conductive slip rings, and a smooth cylindrical massive ferromagnetic armature connected to another coupling shaft.

Design, principle of operation and characteristics of electromagnetic couplings.

Electromagnetic couplings used for automatic control, are divided into dry and viscous friction clutches and sliding clutches.

Dry friction clutch transfers power from one shaft to another through friction discs 3. The discs are able to move along the splines of the shaft axis and the driven coupling half. When current is supplied to winding 1, armature 2 compresses the disks, between which a friction force arises. Relative mechanical characteristics couplings are shown in Fig. 1, b.

Viscous friction couplings have a constant gap δ between the driving 1 and driven 2 coupling halves. In the gap, using winding 3, a magnetic field is created, which acts on the filler (ferritic iron with talc or graphite) and forms elementary chains of magnets. In this case, the filler seems to grab the driven and driving halves of the coupling. When the current is turned off, the magnetic field disappears, the chains are destroyed and the coupling halves slip relative to each other. The relative mechanical characteristics of the coupling are shown in Fig. 1, d. These electromagnetic clutches allow you to smoothly regulate the rotation speed under heavy loads on the output shaft.

Electromagnetic couplings: a - diagram of a dry friction clutch, b - mechanical characteristics of a friction clutch, c - diagram of a viscous friction clutch, d - diagram of the ferrite filler setting, e - mechanical characteristics of a viscous friction clutch, f - diagram of a sliding clutch, g - mechanical characteristics of the clutch slip.

Slip clutch consists of two tooth-shaped coupling halves (see Fig. 1, e) and a coil. When current is applied to the coil, a closed magnetic field is formed. When rotating, the couplings slip relative to each other, resulting in the formation of an alternating magnetic flux, which is the cause of the occurrence of e. d.s. and currents. The interaction of the resulting magnetic fluxes causes the driven coupling half to rotate.

The characteristics of the friction half-clutch are shown in Fig. 1, f. The main purpose of such couplings is to create the most favorable conditions starting, as well as smoothing dynamic loads when the engine is running.

Electromagnetic slip clutches have a number of disadvantages: low coefficient useful action at low speeds, low transmitted torque, low reliability with sudden load changes and significant inertia.
The picture below shows circuit diagram control the slip clutch if equipped feedback by speed using a tachogenerator connected to the output shaft of the electric drive. The signal from the tachogenerator is compared with the master signal, and the difference of these signals is fed to amplifier U, from the output of which the excitation winding of the OB clutch is powered.

Basic control diagram slip clutches and artificial mechanical characteristics with automatic regulation

These characteristics are located between curves 5 and 6, which correspond to the practically minimum and nominal values of the coupling excitation currents. However, an increase in the drive speed control range is associated with significant losses in the slip clutch, which mainly consist of losses in the armature and field winding. Moreover, anchor losses, especially with increasing slip, significantly prevail over other losses and amount to 96 - 97% maximum power transmitted by the clutch. At a constant load torque, the rotation speed of the coupling drive shaft is constant, i.e. n = const, ω = const.

U electromagnetic powder couplings the connection between the driving and driven parts is carried out by increasing the viscosity of the mixtures filling the gap between the clutch surfaces of the couplings with an increase in the magnetic flux in this gap. The main component of such mixtures are ferromagnetic powders, for example carbonyl iron. To eliminate the mechanical destruction of iron particles due to friction forces or their adhesion, special fillers are added - liquid (synthetic fluids, industrial oil or bulk (zinc or magnesium oxides, quartz powder). Such couplings have high speed operation, however, their operational reliability is insufficient for widespread use in machine tool building.

Let's consider one of the schemes for smooth regulation of the rotation speed by the actuator ID, operating through the slip clutch M to the actuator IM.

Slip clutch activation diagram for regulating the rotation speed of the actuator

When the load on the actuator shaft changes, the output voltage of the TG tachogenerator will also change, as a result of which the difference between the magnetic fluxes F1 and F2 of the electric machine amplifier will increase or decrease, thereby changing the voltage at the output of the EMU and the magnitude of the current in the clutch winding.

Electromagnetic couplings ETM

ETM electromagnetic friction clutches (dry and oil) allow starting, braking and reversing in up to 0.2 s, as well as performing dozens of starts within 1 s. The couplings are controlled and powered by direct current voltages of 110, 36 and 24 V. The control power is no more than 1% of the power transmitted by the coupling. By design, clutches are single- and multi-disc, non-reversible and reversible.

Electromagnetic clutches of the ETM series with magnetically conductive disks are available in contact (ETM2), non-contact (ETM4) and brake (ETM6) versions. Couplings with a contact current conductor are characterized by low reliability due to the presence of a sliding contact, therefore, in the highest quality drives, electromagnetic couplings with a fixed current conductor are used. They have additional air gaps.

Non-contact couplings are distinguished by the presence of a composite magnetic circuit formed by a body and a reel seat, which are separated by so-called ballast gaps. The reel holder is mounted motionlessly, thus eliminating the elements of the contact current conductor. Due to the gap, heat transfer from the friction discs to the coil is reduced, which increases the reliability of the clutch in severe operating conditions.

It is advisable to use ETM4 couplings as driving couplings, if this is permissible under the installation conditions, and ETM6 couplings as brake couplings.

ETM4 couplings operate reliably at high speeds and frequent starts. These couplings are less sensitive to oil contamination than ETM2, the presence of solid particles in the oil can cause abrasive wear of the brushes, therefore ETM2 couplings can be used if the specified restrictions are absent and the installation of ETM4 couplings is difficult due to the design conditions of the unit.

ETM6 couplings must be used as brake clutches. Clutches ETM2 and ETM4 should not be used for braking in a “reversed” manner, i.e. with a rotating clutch and a stationary driver. To select couplings, it is necessary to evaluate: static (transmitted) torque, dynamic torque, time transition process in the drive, average losses, unit energy and residual moment of rest.

Application area powder coated couplings determined by the principle of their operation. The product is most widely used in enterprises that use rewinding machines and equipment for cutting bobbins in their work. In such devices, due to powder couplings and magnetic powder torque is transmitted to the operating shafts.

Powder couplings are convenient because by changing the voltage in the excitation winding, the torque can be smoothly adjusted. To transmit torque, a constant voltage must be connected to the clutch. For torque transmission to occur, a special magnetic powder is used.

There are a number of circumstances when the use of powder couplings makes great sense. If quick operation of the mechanism is necessary, then couplings, in which one of the active components is a special powder, come to the rescue.

For coordinated operation of the entire unit, you can also purchase from us controllers for powder couplings . Using the device, functional regulation of the clutch operation occurs.

Principle of operation Powder powder clutches and powder brake clutches based on the interaction of various components. An important element is a special powder, which is always available in our warehouse in sufficient quantity in sealed packaging of 100 grams. Powder, as the main part of the filler, is used together with a coupling, which has a driven and a driving component.

Powder clutches operate in two modes: clutch and braking. Brake units are supplied with powder couplings; such a device is necessary where the braking torque must have variable indicators. Clutches "work" over soft start, acceleration and timely stopping of the mechanism. And a special controller, which you can purchase at our company’s warehouses, can prevent the unit from overloading.

The powder couplings and other products presented in our warehouses, with the help of which the entire unit operates reliably, are subject to operation in any climatic conditions. Temperature products manufactured with European quality, allows uninterrupted operation from -40 degrees to +90 degrees.

Each product offered to our customers is thoroughly tested to ensure compliance with quality and reliability requirements and for the absence of hidden defects.

More detailed information for powder couplings, magnetic powder, controllers and power supplies can be obtained from our company’s specialists or in the catalogs posted on our website.

In the operation of electric drives available in various mechanisms, due to the need for speed, electromagnetic couplings are used. Devices with drive and driven shafts operate due to the fact that an electromagnetic clutch transmits rotation to the elements, causing the mechanism to work. You should know that electromagnetic type coupling connection is an almost exact copy of connections using a hydrodynamic coupling. That is, the scope of application of such a mechanism as electromagnetic couplings corresponds to the area where hydrodynamic analogues are also in demand. For example, when connecting a gearbox and an engine on a ship, it is electromagnetic couplings that are used to transmit torque, as well as to ensure that the vibrations produced by the diesel engine are sufficiently damped.

There are many reasons to use such mechanisms in various devices, since the device fully meets the necessary requirements. The electromagnetic clutch allows you to obtain a gradual, smooth and without jumps transmission of the rotation speed, and also regulates, again, smoothly and without jerks, the transmitted torque. It is precisely because electromagnetic clutches provide smoothness to the entire process, starting from the start of the mechanism, while braking and the necessary change in rotational frequency also occurs gradually and smoothly, leading to the distribution of such an element as the electromagnetic clutch wider than its analogues.

According to the classification, it is possible to describe some differences between the types, for example, electromagnetic powder couplings today are distinguished by true performance. Thus, electromagnetic friction clutches operate almost 15 times slower than a similar powder mechanism, and a hysteretic electromagnetic clutch makes it possible to obtain such characteristics as operating stability and operational durability. At the same time, it is precisely last option– hysteresis couplings – they also differ in that their dimensions are relatively small when compared with the dimensions of other electromagnetic couplings. According to established symbols, the electromechanical properties that one or another electromagnetic coupling shows are designated as MSt -f (Vy). It is these indicators that make it possible to determine what variations occur during the operation of the device, how electromagnetic clutches affect the transmitted torque, and completely depending on how much the current in the winding of a mechanism such as an electromagnetic clutch changes. It is also worth knowing that the residual torque during operation of the mechanism must be significantly lower than the load torque, since otherwise the electromagnetic couplings will rotate the mechanism without any voltage.