During the normal operation of an electrical installation it can be ascertained the occurrence of an event which might, under certain conditions, prove particularly dangerous and damaging.

In particular, during the operation of a current generator, e. g., a car battery or an alternator of the battery-recharging type, sudden and unforeseeable temperature rises occur which involve the same devices and hence the entire electrical installation connected thereto.

Of course, such temperature rises could entail dire effects, leading to plant fires, with the conceivable consequences.

Object of the present invention is to provide a device for the survey of temperature variations in a direct current electrical installation, comprising: a first temperature sensor, apt to survey the temperature of an electric circuit; a first displaying device, connected to said first temperature sensor, apt to display the temperature value of said electric circuit; a second temperature sensor, thermally connected to said first sensor; and a switching device connected to said second temperature sensor, said switching device being apt to activate a first alarm system when the temperature of said circuit reaches a predetermined alarm threshold.

The main advantage of the device according to the present invention is that via the use thereof the trend

of the temperature of the electrical installation can be monitored in real time, thereby immediately assessing any variation with respect to the temperature of the surrounding ambient.

A second advantage lies in that the device according to the present invention comprises an alarm system, which activates when said temperature variations overstep a preset threshold, e. g. of several °C higher than the ambient temperature.

Further advantages, features and modes of employ of the present invention will be made apparent in the following detailed description of a preferred embodiment thereof, given by way of example and without limitative purposes, making reference to the figures of the annexed drawings, wherein: figure 1 is a graph showing the trend of the current in the electric circuit as a function of time; figure 2 is a graph showing the trend of the voltage in the electric circuit as a function of time; , figure 3 is a graph showing the trend of the temperature of the electric circuit as a function of time; and figure 4 is a block diagram of the device according to, the present invention.

Several tests, carried out on different typologies of direct current circuits and electrical installations, highlighted actual temperature rises on parts of the electrical installation.

Figures 1 and 2 are two graphs, of the current I and of the voltage V, respectively, measured in an electric circuit during the testing. Figure 3 is a graph reporting the trend of the temperature T of the electric circuit measured during the same testing.

In particular, the experimental data of measurements carried out on the electric circuit of a car under different operating conditions are reported.

The trend of the current I and of the voltage V

parameters is in both cases substantially constant over time, whereas the trend of the temperature T is uneven, exhibiting even marked variations over time.

Hence, evidently such temperature variations do not depend on specific electrical input conditions of the circuit, nor from malfunctionings of the power supply system.

Notably, in some cases, a 100-110°C temperature is reached, sufficient to set the entire electric circuit on fire, or at least to irreparably damage it.

Moreover, it should be noted that said temperature variations concern the entire electrical installation, and therefore can also damage individual delicate components thereof which be more sensible to a temperature rise.

Moreover, tests and measurements were carried out on new, as well as on already used and partially worn out electrical installations. These tests highlighted that anyhow the hereto described events occur totally at random, with no apparent reason, at any electrical installation, regardless of the age thereof.

Hence, in order to monitor the trend of the temperature in an electrical installation, a device for the survey according to the present invention may advantageously be used, the subsequent figure 4 being a block diagram according to a preferred embodiment thereof.

The device 1 according to the present invention comprises means 2,3,4 for the survey of the temperature. In particular, it comprises a first temperature sensor 2, apt to survey the temperature of parts of an electric circuit 20 to be monitored.

A temperature-displaying device 5 is connected to said first sensor 2, e. g., via a thermal contact implemented with a Copper conductor.

Therefore, by the display 5, the temperature of the electric circuit 20 at issue can be monitored, and the thermal variations thereof can be appreciated.

A second temperature sensor 3 is thermally connected to the first one, e. g. by a metallic member 21 brought into contact with both sensors.

Such second sensor 3 is connected to a switching device 6, e. g., by a thermal contact made by a Copper wire.

The switching device 6 to make and/or to break an electric contact between two conductors when the temperature surveyed by the sensor 3 reaches a predetermined threshold.

Advantageously, a user can adjust this threshold value, e. g. via a thermostatic-type threshold-regulating device 8.

Advantageously, a third temperature sensor 4 is provided in order to survey also the temperature of the ambient in which the electric circuit 20 is immersed.

The sensor 4 is in turn connected to a second temperature-displaying device 9, e. g. a display of analog or of digital type.

Thus, a user can also visually appreciate the temperature difference existing between the monitored circuit 20 and the surrounding ambient.

When the temperature of the electric circuit 20 oversteps the preset threshold, the contacts of the switch 7 are automatically made, powering a first alarm system 10 by means of a power-supplying device 11.

Advantageously, the alarm system 10 comprises acoustical signaling devices, like e. g. beepers and/or sirens, and also visual signaling devices, like e. g. LEDs and/or blinkers.

Hence, the activation of the alarm system enables a user's quick intervention.

The cause of the temperature rises is unknown, therefore, in order to prevent damaging to or fires in the electric circuit, the operator should disconnect the latter, battery included, from the power supply, reconnect it to another spare power supply and replace the culprit power supply as soon as possible.

Advantageously, since the electric circuit 20 to be monitored could lie in an impervious area, a second alarm system 12, connectable to the first alarm system 10 and such as to be activated concomitantly thereto, is provided.

The second alarm system 12 could be connected via a sufficiently long electric cable by a connector, so as to be located in an area accessible to the user and therefore easily seen in case of need.

The present invention has been described hereto according to a preferred embodiment thereof, given by way of example and without limitative purpose.

It is understood that other embodiments of the present invention could be provided, all to be construed as falling within the protective scope thereof, as defined by the annexed claims.