SU829633A1 - Thermal gage - Google Patents

Description

The invention relates to temperature control devices and can be used to protect overheating objects (electromotors, drying chambers, etc.) against overheating. as well as in these, automatic fire alarm topics. Temperature detectors are known that contain the main source of a magnetic field (magnet or electromagnet), a ferromagnetic thermosensitive core with a previously known dependence of magnetic permeability on temperature, and a sealed magnetically controlled switch with an additional adjustable source of magnetic field HI. However, in this detector, the external field (flux) of a permanent magnet is used as a working signal, as a result of which the indicator can be affected by the harmful effects of closely located ferromagnetic masses of extraneous magnetic fields. So, when installing a specified alarm device inside a controlled object that has ferromagnetic parts or its own magnetic fields, the initial setting of the alarm device can be violated up to a complete loss of working capacity. The closest to the present invention is a temperature detector, which contains a sealed magnetically stable contact with the bias winding, placed in a heat-sensitive core, equipped with a heat pipe, made in the form of a thermal probe, installed inside a tubular magnet enclosed in a magnetic circuit, performing simultaneously housing function. In this detector, the harmful influence of magnetic fields on the stability of the relay parameters is eliminated by placing a magnetically controlled contact in a heat-sensitive core installed inside a tubular permanent magnet, on the outside of which

The magnetic circuit is located, which performs the function of the {2J.

However, to ensure reliable transmission of a signal about the achievement of a controlled temperature from this device to a receiving device, it is necessary to take additional technical measures to distinguish the signal about reaching a controlled temperature from the fault modes of both the relay itself (breakage of the bias winding, etc.) and connecting lines (open circuit, short circuit). In addition, two two-wire lines are required to operate the device; to signal the achievement of a controlled temperature and to power the bias winding.

The purpose of the invention is to increase the reliability and reliability of signaling transmission.

The goal is achieved by the fact that an additional winding is inserted in the device, located on a ferromagnetic screen, the windings are connected in opposite to 0 in series with a sealed magnetic control to the input terminals of the device.

FIG. 1 shows schematically the proposed thermal sensor, section; in fig. 2 - its basic electrical circuit.

The proposed sensor contains a sealed magnetically controlled contact 1, a winding 2. Magnetization, a ferromagnetic temperature-sensitive core 3, made of a material with a known dependence of the magnetic permeability on temperature, an additional winding 4, and a magnetic conductor 5 with a cover b, simultaneously performing the functions of a thermal body. sensor; as well as a thermal conductive probe 7, a thin-walled sealed tube from which air is evacuated, and the inner walls are covered with a porous material impregnated with a highly evaporating fluid — a heat carrier; 4, and the second, made in the form of a tube, is brought out through a hole in the magnetic core 5. At the same time, in order to reduce the heat exchange of the heat-conducting probe with the environment, a thermal insulation jacket 8 is installed between the inner surface of the magnetic core 5 and the surface of a part of the thermal probe 7 located on the magnetic core 5. A thermal insulation panel 9 is installed above the upper end of the heat-sensitive core 3 terminals U, to which the terminals of contact 1 and windings 2 and 4 are connected. On the controlled object of the external part of the magnetic core 5, for convenience of sensor installation, an external thread is made.

The device works as follows.

At normal temperature, most of the Magnetic Flux is generated. additional winding 4, in which

. a current flows from the receiving device (not shown), passes through the core 3, shunting the magnetically controlled contact 1. A minor part of the magnetic flux passing through the contact 1,

it is compensated by the countercurrent of the bias winding 2, which is connected anti-parallel to the winding 4 and has a significantly smaller number of turns. When the temperature of the controlled object of a given value -

Curie points of the thermosensitive core 3, the latter loses its magnetic properties, thereby terminating the shunt effect in relation to

contact 1. The redistribution of magnetic fluxes occurring in this case leads to the fact that the flux passing through pin 1 reaches the threshold for triggering the latter.

The opening contact 1 of the switch, connected in series with the anti-parallel windings of the clamping 4 and biasing 2 connected to the input of the receiving device, opens,

The windings are free of windings 2 and 4. This leads to the disappearance of the magnetic field and the closure of the contact, which in turn leads to the supply of current to the winding 4. In the connecting line, pulses appear that are fixed at the receiving device as a signal to reach a controlled temperature. When the connecting line is broken, the current in it disappears completely, and during a short circuit

increases by reducing the resistance by the resistance value of the windings 2 and 4, which is fixed by the receiver as a fault signal.

The electrical circuit of the thermal sensor is operated via one two-wire connecting line.

The present invention significantly expands the temperature range, the control

Claims (1)

Claim A thermal sensor containing a sealed magnetically controlled con. a magnetized winding cycle, placed in a ferromagnetic screen, in thermal contact with which a thermosensor is installed, characterized in that, in order to increase the reliability of the device, an additional winding located on the ferromagnetic screen is introduced into it, the windings are turned on and on with a sealed 5 magnetically controlled contact to the input terminals of the device.