RU2124858C1 - Domestic coffee mill - Google Patents

Abstract

FIELD: domestic equipment for grinding food products, such as coffee, pepper, may be used in food-processing, medical industry and agriculture. SUBSTANCE: coffee mill has drive engine formed as end stator with winding. Working disk with inner surface adapted for receiving and grinding of coffee beans is used as rotor. This disk operates together with other immovable disk-stator provided with similar inner surface. EFFECT: simplified construction, reduced production costs, increased service life and enhanced reliability in operation. 1 dwg

Description

 The invention relates to the field of devices for grinding food products, such as coffee, pepper, cinnamon, and can be used in everyday life, food, medical industry and in agriculture.

 A device is known for grinding food products, comprising a housing with a lid, inside which a working chamber is located, a high-speed commutator motor, on the shaft of which a horizontal knife is mounted.

 Grinding in this device occurs due to the impacts of the knife brought into rotational movement on each unit of the product being ground, for example coffee bean, separately.

However, the practical use of such a machine revealed a number of disadvantages:
the effect of using the working surface of the knife is low due to the action of centrifugal force and concentration due to this grains on the periphery;
the impossibility of achieving uniform grinding (the same size) of the crushed product, because the grains “stick” to the walls of the working chamber due to the “dead zone” formed due to the gap between the periphery of the knife and the inner surface of the working chamber;
high cost and at the same time low reliability of the high-speed commutator motor;
low efficiency of the impact grinding action of the working body - the knife due to close angular speeds of rotation of the knife and grains of the crushed product, because grains rotate with a knife.

 There is also a method of grinding food products in hand mills containing two gear millstones located coaxially and rotated manually (ed. St. N 1329799 class A 47 42/04, 1987). Grinding in these mills occurs due to the tedding of these grains between the gear millstones. The disadvantage of this method of grinding is the imperfection of the manual drive and the low productivity of such mills.

 Based on the study of existing coffee grinder options, the authors came to the conclusion that the closest technical solution to the declared and adopted as a prototype is a device for grinding leguminous material (ed. St. N 1329766 class A 47 42/04, 1987).

 Grinding in this device takes place in a grinding bowl with a pair of millstones fixed in it, one of which is mounted motionless, and the other is mounted on the motor shaft and has the ability to rotate.

 However, the known device has several disadvantages: a complex design, which leads to a decrease in the reliability of the entire unit, as well as low intensity, low quality crushing of food products, as well as low efficiency of using the working surface of the millstone due to the action of centrifugal force and concentration due to this grains on the periphery.

 The main task solved by the invention is to increase the quality and intensity of crushing of food products, such as coffee, while increasing the reliability of the coffee grinder.

 This is achieved by the fact that the drive electric motor is made in the form of an end stator with a winding powered from an alternating sinusoidal current network, and an end rotor without winding, which is one of the working disks, which can be rotated and located relative to the end stator coaxially with the working gap.

 The drawing shows the proposed device.

 The device comprises a housing 1, inside of which a disk 2 with a developed surface is located, which is also the rotor of the end electric motor 3. The housing 1 has rubber bearings 11. On top of the housing 1 is closed by a cover 4, to which a fixed disk 6 with a developed inner surface is mounted on the guides 5. The developed surface of disks 2 and 6 is made by analogy with the working disks of known disintegrators. Between the disks of the movable 2 and the stationary 6 there is a gap 7, in which the grains are ground directly. The cover 4 has a loading hopper 8 with an opening closed by a hatch 9. The end motor consists of a stator 3 with a winding 10 fixedly mounted in the housing 1 and the rotor 2. The necessary clearance 15 between the stator is provided by a shaft 13 fixed in the bearing 12. To prevent crushed product on the surface of the stator and in the bearing they are closed by a lining of copper foil 14.

 Coffee beans for grinding are poured into the working chamber (loading hopper) 8 through the hatch 9 and through the hole in the fixed disk fall on the grinding surface.

 Coffee grinder works as follows. By connecting to the network, an alternating sinusoidal voltage is supplied to the winding 10 of the stator 3, in which an alternating current starts to flow, with a frequency of 50 Hz. A rotating magnetic field arises, and eddy currents appear in rotor 2, caused by the magnetic field of stator 3. These currents determine the appearance of the magnetic field of rotor 2. When the fields of stator 3 and rotor 2 interact (according to Ampere's law), rotor 2 begins to rotate. Coffee beans under the influence of gravity and centrifugal force fall into the loading hopper 8 in the gap between the stationary 6 and the movable 2 disks of the coffee grinder, grinding is in progress. The finished product under the action of centrifugal force is poured into the housing 1, from where after the termination of grinding is removed with the cover 4 removed.

Ultimately, linear velocity is very important for grinding the product. In the proposed device, it is proposed to increase the linear speed of the working body by increasing the radius of the coaxially located disks with developed working surfaces, in accordance with the dependence
V = ωR,
Where
V is the linear angular velocity, m / s;
ω is the angular velocity of rotation of the disks (engine), rad / s;
R is the radius (external) of the working disks, m

где
m - масса зерна, кг;
V - линейная скорость зерна, м/с.Thus, reducing the angular velocity, for example, i times, while increasing their radius also i times, you can keep the linear speed at a constant level, which, ultimately, keeps the kinetic energy of the grain grinding process at a constant level according to the dependence:

Where
m is the mass of grain, kg;
V is the linear velocity of the grain, m / s.

 This, in turn, allows a conventional end induction motor to be used as a drive motor for the working chamber at a power supply frequency of 50 Hz and a rotation speed of 3000 rpm, but with a correspondingly increased radius of the working disks, which allows to maintain a constant linear speed, and therefore increase the efficiency of grinding grain.

 The proposed grinding device has the following advantages: the quality of the ground product is improved; increases the reliability of the device (due to the use of a brushless induction motor); mill cost decreases; longer service life (due to the exclusion of complex elements).

Claims (1)

 A household coffee grinder for grinding food products, comprising a housing with a lid, a working chamber, a working body made in the form of two coaxially arranged disks with working developed surfaces adjoining each other at the ends, one of them being able to rotate and the other is fixed motionless, and drive electric motor, characterized in that the drive electric motor is made in the form of a face stator with a winding powered by an alternating sinusoidal current network, and a face rotor, which serves as one n of working disks, having the possibility of rotation, and located relative to the end stator coaxially with the working gap.