RU2216026C2 - Transmitter of ultimate accelerations - Google Patents

Abstract

FIELD: measurement technology, measurement and recording of discrete accelerations. SUBSTANCE: transmitter of ultimate accelerations incorporates case housing spring-loaded inert body with cutting element mounted for separation of electric conductors coming in the form of wires. Wires are positioned in parallel planes perpendicular to longitudinal axis of transmitter. Cutting element is put perpendicular to longitudinal axis of transmitter. Length l, diameter d and clearance Δ between case and inert body are bounded up with relations l≥0,67•d; Δ = (0,005÷0,017)•d. Cutting element is manufactured in the form of trihedral knife which cutting edge is located perpendicular to wires. Part of case in zone of location of wires is transparent. EFFECT: increased sensitivity of transmitter under impact loads with little duration of action, diminished dimensions of transmitter. 3 cl, 2 dwg

Description

 The invention relates to measurements and can be used to measure discrete values of acceleration and their storage.

 Known maximum acceleration sensor (1), comprising a housing with a set of inertial bodies of various masses located in it, marked in decreasing order of mass and located in dielectric channels, conductors in the form of wires stretched across the channels, and conclusions.

 When acceleration acts on the sensor, each of the set of inertial bodies presses force on its wire, causing destruction of the wires of those cells for which the inertial forces exceed the forces of destruction of the wire. Selecting the mass of inertial bodies and the cross-section of the wires, it is possible to achieve cutting the wires with a certain acceleration step. A cut wire indicates an open current in the sensor circuit and, therefore, a certain level of acceleration.

 The disadvantages of the sensor are large dimensions, since each inertial body and a cut wire are required to register each acceleration value; an error in registering acceleration by the sensor in the event that the sensor was previously exposed to shock or transport vibrations, the values of which do not exceed the limit value of the acceleration of the sensor settings. In this case, the inertial body located above the wire, gradually cutting it, reduces the cross-section of the wire, and at the moment of repeated acceleration exceeding the limit value, a force less than the shear force corresponding to the limit value of the acceleration of the sensor setting is required to cut the wire. How many times the wire cross section decreases, so many times the acceleration value recorded by the sensor decreases.

 The closest in technical essence to the invention is a limit acceleration sensor (2), comprising a housing with an inertial sensing element located in it, consisting of an inertial body pivotally connected to a piston having a dielectric rod, at the end of which a semicircular knife is mounted.

 The inertial body is spring-loaded elastically to the body. On the way to move the knife in a contact group made of insulating material with grooves, a destructible element is installed in the form of wires placed in adjacent parallel planes under the fragile side to each other. The length of the dielectric piston rod is made not less than the distance from the cutting edge of the knife in the initial state to the last wire.

 In the opposite grooves of the contact group are terminals that are connected to the destructible wire. Some ends of destructible wires are connected by a electric wire into a common electric circuit. The other ends of the destructible wires form an independent electrical circuit.

 The acceleration limit sensor operates as follows.

 Under the action of acceleration, the inertial sensing element, compressing the springs, moves. If the acceleration value is sufficient, then the knife sequentially cuts several wires from one side, as a result of which several independent electrical circuits of the sensor are sequentially opened. Cutting each wire corresponds to a specific acceleration value. After the termination of the impact on the sensor, the inertial body together with the piston under the action of the springs returns to its original state.

 The disadvantage of the sensor is the large mass of the inertial sensing element, due to the presence of several components, and therefore, the sensor registers the amplitude value of acceleration for durations of shock loading t≥4 ms.

 With impacts of shorter duration, the measurement error increases significantly.

 In addition, the disadvantage of the prototype is its relatively large dimensions.

 The problem to which the claimed invention is directed is to measure several limiting acceleration values during an accident of a transported object, for example, during explosive loading or repeated impacts, and to reliably store this information with an arbitrary location of the object in space after the accident.

 The technical result obtained by the implementation of the invention is to increase the sensitivity of the sensor under shock loads with a duration of t≥1 ms and reduce the size of the sensor.

This is achieved by the fact that in the limit acceleration sensor containing a housing in which a spring-loaded inertial body is placed with a cutting element mounted to disconnect electrical conductors made in the form of wires and placed in parallel planes perpendicular to the longitudinal axis of the sensor, it is new that the cutting element is installed perpendicular to the longitudinal axis of the sensor, while the length l, the diameter d of the inertial body and the gap Δ between the body and the inertial body are related by the relations:
l≥0.67 • d;
Δ = (0.005 ÷ 0.017) • d. (1)
The specified implementation of the sensor allows to increase its sensitivity, since the inertial sensitive element with a knife has a mass of ~ 3 times less than the prototype, which allows the sensor to respond to impacts of shorter duration. When moving under the influence of inertial forces, the knife of the inertial body sequentially cuts the wires located at a certain distance from each other and, thereby, the electrical contacts are sequentially opened. By changing the parameters of the sensor element of the sensor (mass of the inertial body, the characteristics of the springs) and the distance between the wires being cut off, various compression forces of the sensor can be achieved at which the sensor contacts open. The opening of each contact corresponds to the measurement and storage of the acceleration limit values.

 Direct installation of the knife in an inertial body can significantly reduce the size and weight of the sensor.

 The implementation of the sensor, taking into account relation (1), allows its operability at various angles of impact with respect to the sensitivity axis of the sensor. For l <0.67 • d and Δ> 0.017 • d, the inertial body is skewed relative to the longitudinal axis of the sensor. When Δ <0.017 • d, friction increases when the inertial body moves relative to the body, which leads to an increase in the measurement error.

 Relay opening of the sensor electric circuit is achieved by the fact that, firstly, the trihedral knife in the process of cutting the wire pushes its cut ends, and secondly, the stretched wire between the terminals, several tens of microns in diameter, twists and leaves the cut zone after cutting. The knife of the inertial body slides along the groove of the dielectric body of the contact group when moving, where the cut wires are located and is electrically isolated from the sensor body. The implementation of the part of the sensor housing in the transparent wire location zone allows you to visually determine the acceleration value that the sensor registered and remembered by opening the sensor contacts.

 Figure 1 shows a longitudinal section of the inventive sensor.

 Figure 2 shows a top view of the sensor.

 The drawings show a limit acceleration sensor for recording three discrete acceleration limit values. The acceleration limit sensor comprises a housing 1 with a longitudinal groove, in which an inertial body 2 with a cutting element insulated with a cup 3 and made in the form of a trihedral knife 4, two springs 5, 6, a cover 7 with a hole in the center, a removable contact group 8 with a groove are placed in the center to ensure the movement of the knife 4, emphasis 9, the adjusting nut 10.

 Contact group 8 contains four contacts 11, 12, 13, 14, three electrical conductors in the form of wires 15, 16, 17, placed in the slots of the dielectric housing of the contact group 8 and a transparent cover 18. In this case, the wires are placed in parallel planes perpendicular to the longitudinal axis sensor. Contacts 11-14, 12-14, 13-14 are connected respectively by wires 15, 16, 17 by laser welding or soldering. In the housing of the contact group 8 is placed at least three groups of contacts.

The knife 4 is mounted on the inertial body 2 perpendicular to the longitudinal axis of the sensor with the possibility of cutting the wires 15, 16, 17. The cutting edge of the trihedral knife 4 is perpendicular to the wires 15, 16, 17. Length l, diameter d of the inertial body 2 and the gap Δ between the body 1 and inertial body 2 are connected by the relations:
l≥0.67 • d; Δ = (0.005 ÷ 0.017) • d
At fixed distances between the wires, the parameters of the springs 5, 6 are selected by calculation, based on what acceleration values need to be registered. Preliminarily, the force of movement of the inertial body 2 with the knife 4 is determined using the technological rod that passes through the hole on the cover 7. The force or acceleration at which the knife 4 of the inertial body 2 cuts the first wire 15 is set using the adjusting nut 10 when the sensor is quasistatic centrifugal installation. The cross section of the wires 15, 16, 17 is selected based on the fact that the shear force with a knife should be less than three percent of the inertial forces acting.

 The experimental values of the accelerations at which the wires 15, 16, 17 are cut by the knife 4 of the inertial body 2 are compared with the calculated data. If their difference does not exceed 10%, then in the contact group replace the cut wires or replace the contact group with wires with a new one. After that, the sensor is used for its intended purpose.

 The acceleration limit sensor operates as follows.

 Under the action of acceleration, the inertial body 2, compressing the springs 5, 6, moves to the right. If the acceleration value is sufficient, then the knife 4, moving together with the inertial body 2, sequentially cuts, for example, the first and second wires 15 and 16, as a result of which the relay relays in series with two independent sensor circuits. Cutting each wire corresponds to a specific acceleration value. After the termination of the impact on the sensor, the inertial body 2 with the knife 4 under the action of the springs 5, 6 returns to its original state.

 If the shock effect on the object in which the sensor is installed is repeated and the acceleration value is greater than in the first case, then the sensor registers the acceleration value when the shock parameters are equal to or greater than the maximum setting value of the third sensor contact.

The sensor has a response diagram with a solid angle of ~ 70 ^o , which is ensured by the presence of a gap between the inertial body 2 and the housing 1, as well as a certain ratio between the length l and diameter d of the inertial body. To obtain an omnidirectional, spherical diagram of the operation of the registrar, it is necessary to use six sensors in the registrar, located one sensor along the axes of the Cartesian coordinates.

If the sensor is used:
- in stand-alone mode, when there is no electric voltage at the terminals, then during the shock process several contacts are opened sequentially, which indicates the registration of several values of acceleration. By visual observation of the state of contacts, the maximum acceleration acting on the object under study is estimated;
- in the measuring system, when sequentially cutting the sensor wires, a stepwise voltage change is recorded in the measuring system. The number of voltage steps determines the sequential value of the accelerations acting on the studied object.

SOURCES OF INFORMATION
1. The maximum acceleration sensor. USSR copyright certificate 528509, cl. G 01 P 15/04, publ. in BI 34, 1976

 2. Sensor of maximum accelerations. RF patent 2077816, MKI G 01 P 15/04, publ. in BI 11, 1997

Claims (4)

1. The maximum acceleration sensor, comprising a housing in which a spring-loaded inertial body is placed with a cutting element mounted to disconnect electrical conductors made in the form of wires placed in the dielectric housing of the contact group in parallel planes perpendicular to the longitudinal axis of the sensor, characterized in that the cutting element is mounted directly on the inertial body perpendicular to the longitudinal axis of the sensor, grooves are made in the sensor housing and the contact group housing bespechenii of the cutting element, wherein the length l, the diameter d of the inertial body, and a gap Δ between the sensor body and the inertial body are related by
l≥0.67 d;
Δ = (0.005 ÷ 0.017) d.  2. The sensor according to claim 1, characterized in that the cutting element is made in the form of a trihedral knife, the cutting edge of which is perpendicular to the wires.  3. The sensor according to claim 1, characterized in that in the case of an inertial body made of an electrically conductive material, the cutting element is made isolated from it.  4. The sensor according to claim 1, characterized in that part of the housing in the area of the wires is made transparent.

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