RU2237310C2 - Inertia switch - Google Patents

Abstract

FIELD: measurement of sustained accelerations in automatic systems of flight vehicles and safety systems of automobiles.

SUBSTANCE: in the inertia switch, having a body with a cover, inertia body and contacts, the body is filled with liquid, the inertia body is made in the form of a flat disk and is positioned in liquid in the body interior for plane-parallel motion between two plane walls, the value of motion is less than its diameter, but more than the clearance between the body wall and the flat disk in its initial position. The fixed contacts are installed in the body, and the movable ones are made of elastic material and positioned in circumference around the inertia body for engagement with it. In the initial position the flat disk is held by a magnetic system.

EFFECT: provided non-operation at high-frequency vibration-impact actions and provided measurement of accelerations under the action of vibration.

2 dwg

Description

The invention relates to inertial switches for automation systems of various aircraft and vehicle security systems.

Currently, there are a variety of designs of inertial switches, but all of them, having certain drawbacks, in most cases cannot be widely used to measure accelerations in these systems.

Known inertial switch is an acceleration fuse containing a housing, an inertial body, consisting of several inertial elements, a transmitting element in the form of a cylinder filled with liquid, with a movable piston / 1 /.

In the known inertial switch, it is very problematic to provide a reliable seal in the movable seating of the piston. The switch has a lot of moving parts, which in case of unstable friction will cause additional errors of operation. Due to the design features of the switch (fluid outflow through the nozzle), it only works when the acceleration is very long. The switch does not have time to respond to short acceleration pulses. This greatly limits the scope of the known inertial switch.

Known inertial switch is an automobile sensitive mechanical contact sensor containing a housing, an inertial body, pressed by a contact spring and damped by a damping lamella / 2 /.

The inertial switch has a large operating error due to the instability of friction between the inertial body and the damping lamella, which significantly limits the use of the known switch.

Known inertial switch is an acceleration sensor containing a housing with a lid, an inertial body in the form of an elastic balloon filled with liquid, held by a magnetic system, contacts / 3 /.

The disadvantage of the inertial switch is that it responds to very short acceleration pulses, which in most cases are not dangerous for the objects of use.

That is, the known switch cannot be widely used, for example, for security systems, due to its responses from high-frequency vibration-shock accelerations, which significantly limits the possible areas of application of the switch.

This inertial switch is considered as a prototype.

An analysis of the structures of known inertial switches allows us to conclude that they contain inertial bodies either completely non-damped, or damped unstably, or very deeply damped, which accordingly leads either to a response to very short acceleration pulses, or gives large errors in measuring accelerations, or provides measuring only very long-acting accelerations.

A review of the designs of known inertial switches allows us to conclude that the prior art does not provide the creation of inertial switches that ensure their use for measuring accelerations in various fields of application, for example, under vibration impacts.

Therefore, the problem solved by the invention is the provision of failure during high-frequency vibration impacts and the provision of measuring accelerations under the action of vibration.

The specified technical result is achieved by the fact that in the inertial switch containing the housing with a cover filled with liquid, the inertial body held by the magnetic system, the contacts, according to the invention, the inertial body is made in the form of a flat disk placed in the liquid in the internal volume of the body, with the possibility of plane parallel moving between two flat walls, and interacting with the contacts, moreover, the movement of the disk is much smaller than its diameter, but significantly larger than the gap between the wall and disk in its original position.

The execution of the inertial body in the form of a flat disk, making plane-parallel movement between two walls in an internal volume filled with liquid, when the disk moves much smaller than its diameter, but much larger than its clearance with the wall in the initial position, provides inertial body damping, and variable damping, depending on slew rate, duration of action and magnitude of acceleration.

This damping is greatest in the initial position of the inertial body during shock accelerations with a high slew rate (short leading edge).

At the beginning of the movement of the inertial body from its initial position, the liquid does not have time to instantly flow into the annular gap between it and the wall, since the gap according to the invention is extremely small, and the diameter of the disk (and therefore the area) is significant. With a slight increase in the gap, the increase in volume behind the disk is significant.

The decrease in pressure behind the disk due to this additionally prevents the inertial body from moving from its original position, and the magnitude of the force holding the disk is proportional to its area. With very short impacts of acceleration, even with an amplitude significantly exceeding the setpoint (acceleration) of operation, the disk moves a very short distance and returns to its original position, that is, the inertial switch will not work.

When moving the disk from the initial position to the intermediate, the gap increases so much that the liquid flows freely into this annular gap, as a result of which the damping of the disk is significantly reduced.

Under the action of accelerations of longer duration with a small slew rate (with a longer leading edge), the liquid will have time to fill the increasing volume behind the disk through the annular gap, i.e., there will be no decrease in pressure behind the disk, therefore, there will be no holding force.

Guaranteed, although a small gap between the wall and the disk in its original position eliminates sticking of the disk.

The excess movement of the disk over the specified gap eliminates a significant increase in fluid pressure in front of the disk, since the liquid in front of the disk is displaced through the annular gap of a significant magnitude.

Thus, in the inertial switch, a variable damping of the inertial body is ensured, which is greatest in the initial position at small displacements from the initial position, depending on the slew rate, magnitude and duration of acceleration and much weaker in other positions of the inertial body. This allows you to create an inertial switch, not triggered by high-frequency vibration shock accelerations, triggered by linear accelerations in the presence of vibration, triggered by accelerations of a wide range of durations.

The inertial body in the inventive inertial switch is, as it were, additionally held in extreme positions by the arising restraining forces from decreasing the pressure between the wall and the disk under the action of accelerations with a high slew rate, a large magnitude and a short duration (high-frequency vibro-shock accelerations).

Significant damping of the inertial body in the initial position allows you not to respond to the vibrational components of the accelerations, as if to “smooth” them, which allows the measurement of accelerations under the action of vibration with an acceptable error.

In the inertial switch, a small number of parts, only the inertial body moves, which should ensure high reliability of the claimed switch.

The invention is illustrated by drawings.

Figure 1 shows a longitudinal section of an inertial switch in the initial state.

Figure 2 is a longitudinal section in the worked state.

The inertial switch contains a housing 1 with a cover 2 made of non-magnetic material and connected hermetically, forming an internal cavity filled with liquid 3.

In the internal cavity of the housing 1 between the walls 4, 5 is placed an inertial body 6 in the form of a disk. The inertial body 6, made of soft magnetic material, is held in its original position by a magnetic system 7.

The inertial body 6 in the initial position interacts with several movable contacts 8 of one form or another, made of elastic material and located around the circumference around the inertial body 6.

Fixed contacts 9 are installed in the housing 1 through insulators 10.

The gap Δ between the wall 4 and the inertial body 6 is much less than the possible movement "a" of the inertial body 6, determined by the distance from the latter to the wall 5 of the cover 2. The gap Δ is determined by the protrusions 11 (Fig. 1).

The inertial switch may be equipped with a device for compensating for thermal changes in the volume of liquid 3 (not shown).

The inertial switch operates as follows.

Under the action of acceleration with a value equal to or greater than the setpoint, in the direction of arrow 12, the inertial body 6 moves in the opposite direction, releasing the contacts 8, which are closed on the fixed contacts 9 (figure 2).

After the termination of the acceleration, the inertial body 2 is returned by the magnetic system 7 to its original position, opening contacts 8, 9.

The adjustment of the acceleration response is carried out by axial movement of the magnetic system 7.

Under the action of acceleration with a value less than the set point, the inertial body 6 remains in its original state, since the attractive force of the inertial body 6 by the magnetic system 7 exceeds the force acting on the inertial body from the action of acceleration. The inertia switch does not work.

When acting in the direction of actuation in the direction of arrow 12 of short accelerations of acceleration, the inertial body 6 does not have time to move from its initial position during the impact by the amount of displacement leading to the switching of contacts 8, 9, since the liquid does not have time to flow into a slightly increasing, but very small gap Δ, which leads to a decrease in pressure in this gap. Therefore, an additional force arises, which returns the inertial body 6 to its original position, due to the pressure difference from the ends of the inertial body 6. The inertial switch does not work.

Similar forces act on the inertial body during vibrational accelerations, that is, vibration does not cause false responses of the claimed inertial switch.

Thus, the use of the claimed inertial switch will allow:

- exclude triggering from shock accelerations of short duration;

- exclude triggering from high-frequency vibration accelerations;

- provide a response (acceleration measurement) under the action of vibration.

In addition, due to the simplicity of the design of the inertial switch (contains less than 10 parts of simple shape, only the inertial body moves), high reliability and low cost are ensured.

мм.The inertial switch can be made in dimensions

mm

Sources of information

1. The acceleration fuse, the patent of Germany No. 3313713 A1 (figure 2), F 42 c 15/24, 1983

2. Automotive sensitive mechanical contact sensor. Europatent No. 689219 A2, H 01 35/14, 1992

3. Acceleration sensor, RF application No. 95100890/02 A1, F 42 c 15/24, 1995, publication 1996 (prototype).

Claims (1)

An inertial switch comprising a body with a cover, an inertial body, a magnetic system and contacts, characterized in that the body is filled with liquid, the inertial body is made in the form of a flat disk of soft magnetic material and is located in the liquid in the internal volume of the body with the possibility of plane-parallel movement between two flat walls the housing, fixed contacts are installed in the housing, and the movable contacts are made of elastic material and are located around the circumference around the inertial body with the possibility of mutual When interacting with it, in the initial position the flat disk is held by the magnetic system, while the amount of movement of the flat disk is less than its diameter, but greater than the gap between the wall of the case and the flat disk in its initial position.

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