SE469048B - UPSET SENSOR - Google Patents

Description

DISCLOSURE OF THE INVENTION The object of the present invention is therefore to provide a disturbance sensor of the kind initially indicated, which gives an indication of disturbance of the sensor only after a plurality of contact closures, whereby natural inclination changes, e.g. eg settlements in the ground, does not give a disturbance indication.

Another object of the present invention is to provide a disturbance sensor of the kind initially indicated, which can distinguish between different rapid processes of the contact changes, and which prevents indication of disturbance of the sensor, if the disturbance results from rapid contact changes due to an explosion near the sensor.

These two objects are achieved in that the disturbance sensor according to the present invention has obtained the features stated in claim 1.

Further developments of the invention appear from the other claims.

DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below with reference to the accompanying drawing, which shows a preferred embodiment of the invention.

Fig. 1 schematically shows a sensor head, seen from above, included in a disturbance sensor according to the present invention.

Fig. 2 shows an electrical circuit diagram of an electronic circuit included in the disturbance sensor according to the present invention. .fu-x 10 15 20 25 30 35 469 048 PREFERRED EMBODIMENT Fig. 1 shows a disturbance sensor 1 for sensing disturbance of a not shown, buried, explosively charged land terminal. The sensor 1 consists of a cylindrical housing (or housing) 2 with an easily movable contact member in the form of a metallic ball 3.

The ball 3 rests on a surface 4 in the housing 2, surrounded by a ring and at equal distances from each other, fixedly arranged contact points in the form of contact pins (twelve in the shown embodiment), denoted by I (three) , II (six pieces) resp. III (three pieces), all insulated from the bottom surface 4 in the house 2.

The bullet 3 has the ability to move quickly along the surface 4, if the mine (and thus the housing 2) is subjected to a shock or disturbance. The ball 3 can alternatively consist of a drop of mercury.

The twelve contact pins I-III are connected according to a predetermined pattern to a contact terminal a, b resp. c. The contact terminal a, to which the pins II are connected, serves as an input terminal in an electronic circuit 5 belonging to the sensor 2, as shown in Fig. 2. The contact terminal b, to which the pins I are connected, is connected to a supply voltage + U1 volts. The contact terminal c, to which the pins II are connected, is connected to earth, but may alternatively have a predetermined other potential.

The ball 3 in Fig. 1 is capable of, as a result of an accidental movement, moving over contact with two of the contact pins, namely either with a pin I and a pin II, or with a pin II and a pin III. The contact pins are so placed that the ball 3 can never make simultaneous contact with a pin I and III, would have meant that the supply voltage would be short-circuited by disturbance of the sensor housing 2, the surface 4 of the housing 2 at the same time as this otherwise 469 048 10 15 20 25 30 35 against earth.

The ball 3 thereby has the same function as a switch, and has therefore been shown in Fig. 2 as a contact 3 '. The contact 3 'can assume two different positions, namely a position where it makes contact with the terminal b, i.e. connects the supply voltage U1 to the input terminal a in the circuit 5, and another position, where it makes contact with the terminal c, i.e. connects the input terminal of the circuit a to earth. These two positions correspond to the contact of the ball 3 with pins I and II, respectively. with pins II and III.

The electronic circuit 5 contains between the terminals a and c a series connection of a capacitor C1, a diode D1 connected in its blocking direction (relative to the supply voltage U1) and a resistor R1, and a parallel connection of a capacitor C2 and a resistor H2. These two connections are separated from each other by a diode D2 connected in its direction of rotation (relative to the supply voltage).

The voltage Ud across the resistor R2, ie at the connection terminal d in Fig. 2, is supplied to a comparator 6, where the voltage Ud is compared with a predetermined reference voltage Uref. If the voltage Ud is greater than or equal to Uref, an output signal is obtained on the comparator's terminal e, indicating a disturbance of the mine.

The function of the electronic circuit 5 will now be described in more detail. To increase the understanding of the function of the circuit, it is assumed that the following exemplary values apply: U1 = 10 volts, C1 = 10nF, C2 = 90nF, R2 = 1M0hm.

If 01 is initially discharged, a voltage peak is obtained at point C1 / D1 / D2, when the contact 3 'is closed towards U1.

Since the capacitance of C1 is 9 times greater than the capacitance of C2, U1 is distributed with 9.0 volts across C1 and 1.0 volts across C2, provided that the voltage drop across diode D2 is negligible. In order to re-obtain a charging current through C1 at a new slope towards U1, C1 must first have been discharged, which takes place by closing towards ground, ie towards terminal c. If such discharge of C1 has taken place, while C2 has essentially maintained its charge due to its high time constant RÉCZ, at the next close to U1 a voltage of 9.0 volts will be distributed between C1 and C2, meaning that the voltage across C2 rises from 1.0 to 1.9 volts. A further discharge of C1, followed by a slope towards U1 gives an additional charge addition to C2 of 0.81 volts, and so on. The voltage Ud across C2 therefore rises successively to a level equal to or greater than the reference voltage Uref, the comparator 6 giving the above-mentioned output signal on the terminal e.

If C1 is not fully discharged, the voltage peak at point C1 / D1 / D2 becomes small. How quickly discharge of C1 occurs when closing the contact 3 'to earth is determined by the resistance in the resistor R1.

At rapid contact changes of the ball 3 (shocks arising from an explosion in the vicinity of the mine), the amplitude of the voltage peak becomes low, and the charge addition in C2 is small.

During slow contact changes (inclination and movement of the mine), the voltage peak becomes high and the charge increase in C2 is greater.

It will be appreciated that the time constant R2C2 must be so large that the discharge which takes place between the voltage peaks is not greater than the respective charge addition.

By suitable dimensioning of the various circuit components, the sensitivity of the sensor can easily be varied from case to case.

Claims (3)

Ö \ \ 0 10 15 20 25 30 35 $> P a t ein t khr a v A disturbance sensor for sensing disturbance of the sensor from a predetermined rest position, comprising a housing (2) and an easily movable, metallic contact member (3) in the housing capable of moving at random in the slightest disturbance of the sensor housing into simultaneous contact with two of a plurality of electrical contact points (I-III) fixed in the housing and thereby, as a switch (3 '), closing an electrical contact between the two contact points, which contact closure is an indication of a disturbance of the sensor, characterized by that, in order to provide the disturbance indication only as a result of a plurality of such contact connections, the contact points (I-III) are so connected to an electronic circuit (5) included in the sensor that each said contact connection randomly either connects a supply voltage (U1 ) to the circuit or disconnects the supply voltage from the circuit, the circuit containing a capacitor (C2), which is dimensioned that at each said connection of the supply voltage receive a charge addition, but that at each mentioned disconnection of the supply voltage is not significantly discharged, whereby the voltage (Ud) across the capacitor (C2) after a certain number of connections of the supply voltage has gradually reached a predetermined level (Uref ) corresponding to said plurality of contact terminals, and wherein said capacitor (C2) is connected in series with a second capacitor (C1), which is included in an RC circuit (R1, C1), which is dimensioned so that the second capacitor (C1) does not has time to be appreciably discharged at such rapid contact closures of the movable contact member, which occurs when the sensor is disturbed as a result of an explosion in the vicinity of the sensor, which failure to discharge the second capacitor (C1) results in a subsequent connection of the supply voltage ( U1) across the circuit prevents charge current from flowing significantly through the two capacitors and thus essentially prevents charge additions to the first capacitor (C2). and 10,469,048 Sensor according to Claim 1, characterized in that the sensor housing (2) is rigidly connected to an exploded mine buried in the ground. Sensor according to any one of the preceding claims, characterized by a voltage comparator (6) for sensing the voltage (Ud) across the first capacitor (Ci) and comparing it with a reference voltage (Uref) corresponding to said predetermined level.