JPS6257932B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a vibration mechanism that has a vibrating body that protrudes into a container and is configured as a vibrating rod, and that damps vibrations when it comes into contact with a filling in the container; The present invention relates to a device for detecting or monitoring the filling height in a container, and having means for displaying or opening/closing operations according to the above.

Devices of this type are generally known. The principle is to utilize the effect that by applying an impact to the filling, vibration energy is released from the vibration mechanism to the filling, and the vibration of the vibration mechanism is attenuated.

At least 1 at which bending vibrations are excited at the resonant frequency
A device in which a vibrating rod or vibrating body protrudes into the container to be monitored, and when it comes into contact with the filling, its vibration is damped, and the filling height is indicated by the change in vibration is disclosed in West German Patent No. 582,760 and the British Patent. No.
It is known from Publication No. 1013186.

However, in the filling height measuring device described above, a large alternating force based on the vibration of the individual vibrating rods is applied to the fixing device and the wall of the container, and the vibration energy is transmitted from the vibrating rod to the wall of the container. The loss of vibrational energy is considerable even when no packing material is present around the vibrating bar, so the vibrating drive system must be designed to be powerful in order to maintain the operation of the monitoring device. There must be. the result,
When measuring the height of a light filler with a small damping capacity, this device also has the disadvantage that vibrations are not sufficiently damped and the height of the light filler cannot be detected by this device.

In order to avoid the above disadvantages, instead of one vibrating rod, two vibrating rods arranged parallel to each other are protruded into the container, and the fixed point of the vibrating rod is connected to the tuning fork via a connecting member. A proposal was made to connect the two vibrating rods in such a way as to produce bending vibrations in opposite directions (West German Patent Application Publication No. 1773815). However, this tuning fork-shaped device is significantly larger than a measuring device with a single vibrating rod, and
Powder-like or fibrous filler gets caught between the vibrating rods, and granules tend to adhere to the vibrating rods, which has the disadvantage that strong damping of the vibrating mechanism occurs even when the fill height is low.

The object of the invention is to detect and monitor the filling height in such a way that no vibrational energy is transmitted to the walls of the container, a very accurate monitoring of the filling height in the container can be carried out, and without the need for expensive structures. The purpose is to provide equipment.

Furthermore, it is an object of the invention to prevent the vibration mechanism from giving rise to false readings. Mismeasurements can be caused, for example, by the filling getting caught in the vibrating mechanism.

The above object is achieved by providing two vibrating bodies arranged one above the other as a vibrating mechanism,
This is achieved by configuring the vibrating body as a vibrator that rotates back and forth with the same resonance frequency, and manufacturing the two vibrating bodies so that the rotating directions are always opposite when measuring the filling height. It was done.

The vibrating bodies are arranged in the center of each membrane, which acts as a return spring, and the outer edges of the membranes are connected to one another via tubes. Since the torques generated from both vibrators and acting on the tube are in opposite directions, they cancel each other out on the tube. In this case, the center of gravity of each vibrating body is located at the center of the corresponding membrane and at the rotation axis of the vibrating body, so that the center of gravity of the entire vibrating mechanism does not vibrate and therefore the vibration energy that causes the center of gravity to vibrate is eliminated. formed as above. In this way, the entire tube can be formed as a vibration node of the vibration mechanism. The tube of the vibrating mechanism is suspended via an annular membrane in a screw-on piece and is attached via this screw-on piece to the wall of the container whose filling height is to be monitored.

In order to vibrate a vibration mechanism made of a non-magnetic material, for example, an excitation iron core, an excitation coil wound around the excitation iron and through which a pulsating direct current is passed, and an excitation coil embedded in each vibrating body to excite the excitation iron core. It is preferable to use an electromagnetic drive consisting of a total of two movable pieces that are attracted when the actuator is moved. In that case, the excitation core is provided with two parallel legs protruding toward the vibrating body, and the free ends of the legs are arranged so as to face the movable piece embedded in the vibrating body. Ru.
Further, detection of vibrations of the vibrating body is performed by an electromagnetic device disposed on the opposite side of the electromagnetic drive device with respect to the vibrating body and comprising a bar magnet and a coil surrounding at least a part of the bar magnet. According to the electromagnetic device, when the vibration mechanism vibrates, a voltage is induced by the movement of the bar magnet within the coil, and this voltage is converted to a pulsating direct current via an amplifier and sent to the excitation coil. . In order to be able to measure and monitor the filling height in a container in which the device according to the invention is installed, the output of the amplifier is fed via a limit value discriminator to a suitable display device or to a relay for controlling other devices. Ru.

When it is necessary to miniaturize the device of the present invention so that it can be installed at any location on the wall of the container without reducing the accuracy of monitoring, a configuration that further improves or develops the present invention is adopted. be able to.

One method to meet the above-mentioned demand for miniaturization is to arrange two vibrating bodies coaxially, and to intertwine at least some of them with a space between them.

This solution retains the advantage that only a vibrating body in direct contact with the monitored filling is required to detect the filling height, while avoiding the disadvantage of high alternating forces acting on the fixing device. can be avoided.

In an improved configuration of the invention, the first vibrating body protruding into the container protrudes into a cavity provided in the second vibrating body. Instead of the above configuration, the problem can also be solved by having the first vibrating body protruding into the container have a cavity, and the second vibrating body protruding into the cavity.

Further, both vibrating bodies are respectively disposed at the center of a membrane that functions as a return spring, and the plane of the membrane is perpendicular to the axis of the vibrating body in a resting state, and the outer edges of the membranes are mutually connected to each other via a tubular body. Preferably, they are combined.
In that case, the vibrating body is selected in such a way that the torque generated by the vibrating body and acting on the tube is canceled out in this tube.

The center of gravity of each vibrating body is preferably located at the center of the membrane and on the axis of rotation of the vibrating body so that the center of gravity of the entire vibrating mechanism remains stationary when measuring the height of the filling. By adopting the above structure, the entire tube is formed to serve as a vibration node of the vibration mechanism. The device of the present invention, which includes a vibrating mechanism consisting of a vibrating body, a membrane, and a tubular body, is suspended by an annular membrane on a threaded piece, and the height of the filling is measured by the threaded piece on the wall of the container. The device can be installed on.

In a preferred embodiment of the invention, the first vibrating body is formed of a solid cylindrical body, the solid cylindrical body is rigidly connected to a hollow cylindrical body, and the free lower end of the latter is crushed flat. It is formed in a curved shape. This shape is effective for obtaining good sensitivity when the vibrator comes into contact with the filling to be tested. A second vibrating body, disposed coaxially with the first vibrating body, consists of two tightly coupled upper and lower cylindrical bodies, which cylindrical bodies are connected to the solid cylindrical body of the first vibrating body. It has a through hole for accommodating the upper part. The two cylinders are rigidly connected to each other in the center of the membrane via a third cylinder which has a smaller diameter than the two cylinders and is also provided with a hole.

As the vibration drive device, an electromagnetic device is suitable, and an excitation coil is built in the upper cylindrical body of the second vibrating body, and the coil is surrounded by a tube forming an excitation iron core, and the tube is simultaneously Forms the outer peripheral surface of the upper cylindrical body. Since the excitation coil is fixedly installed inside the upper vibrating body, it is an element that increases the moment of inertia of the vibrating body. As a result, the weight and space requirements of the vibration mechanism are reduced. The tube surrounding the excitation coil is made of magnetically soft material. The two pins, also made of magnetically soft material, form magnetic poles, and the portion of the first vibrating body, also made of magnetically soft material, that projects into the excitation coil is It acts as a yoke for the magnetic circuit that belongs to the drive mechanism.

A pulsating direct current is sent to the excitation coil to drive the vibration mechanism. Also, as a vibration detection device,
It is preferable to use a piezoelectric element in the form of a plate. The piezoelectric element is fixed on the membrane of the first vibrating body, which acts as a return spring. Of course, the piezoelectric element
It can be replaced by a well-known foil strain gauge placed on top of the membrane. Both piezoelectric elements and foil strain gauges have the advantages of occupying little space, having low weight, and being electrically and mechanically robust. The electrical signal generated by the vibration detection device is converted into a pulsating direct current by an amplifier, and this current is passed through the excitation coil of the vibration drive device, as described above. Due to the current flowing through the excitation coil, the vibration system is excited at a resonant frequency, provided that the vibrator projecting into the container does not come into contact with the filling. A limit value discriminator is connected to the output of the amplifier, which provides an output signal for indicating the vibration condition, i.e., the filling height, and for driving the relay.

In another preferred embodiment, in order to obtain good filling height detection sensitivity, the first vibrating body is configured as a hollow cylindrical body, the upper part of which is connected to the membrane,
The second vibrating body is formed into a solid cylindrical body with a flattened lower end, and the lower end protrudes into the hollow cylindrical body. In this case, the upper half area of the solid cylinder is connected to the center of the membrane.

In this embodiment as well, by selecting the mass distribution of the vibrating bodies, the center of gravity of each vibrating body is at the center of its rotation, that is, the center of the corresponding membrane, and the center of gravity of the entire system is maintained during vibration. It can be configured so that it remains stationary and no vibrational energy is transmitted to the walls of the container.

In particular, in the preferred embodiment described above, it is also possible to arrange the centers of gravity of the two vibrating bodies at positions different from their respective centers of rotation. By shifting the center of gravity in this manner, it is possible to further simplify and downsize the vibration mechanism while avoiding the risk of the center of gravity of the entire vibration mechanism vibrating while the device is operating. To obtain this advantage, the condition that the deflection of the center of gravity of each vibrating body from a resting state is equal to the product of the weight of the vibrating body, and the centers of gravity of both vibrating bodies are the same in the resting state. In order to do so, the two individual vibrators must be manufactured in a mutually intricate structure.

By appropriately distributing the weight of the vibrating body in front and behind the membrane supporting the vibrating body, the center of gravity of the vibrating body can be easily moved so as to satisfy the above-mentioned conditions. In the preferred embodiment described above, it is of course possible to move the center of gravity of the vibrating body out of the plane of the membrane.

A piezoelectric system is suitable as the vibration drive device and the vibration detection device. For this purpose, the tube connecting the outer edges of the two membranes can be divided transversely to the axis and two piezoelectric elements can be mounted between them. The two piezoelectric elements must be fixed so that they are located between the two divided parts and in the plane of vibration, so that one of them is used as a vibration drive device and the other as a vibration detection device.

The amplifier connected between the above systems vibrates greatly when the vibrating body protruding into the container is not covered with the filling, and when the rod protruding into the container comes into contact with the filling, the vibration system This acts to dampen the vibrations of the A limit value discriminator fed with the output of the amplifier delivers an output signal indicative of the vibration state of the vibrating body, ie the height of the filling.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The apparatus of the present invention shown in FIG. 1 includes two vibrating bodies arranged one above the other. Among them, the first vibrating body 1a arranged on the lower side is made of a cylindrical block 1 and a rod-shaped part 2 connected thereto and inserted into a container (not shown) containing a filling body inside. Become. The first vibrating body 1a is supported at the center of a membrane 3 provided at the lower part of the tube 7, and the end of the rod-shaped portion 2 extending downward in the figure protrudes into the container. The lower part of the rod-shaped portion 2 is drawn thinly in Figure 1, but when viewed in a direction perpendicular to Figure 1,
As shown in FIG. 2, it is formed to have a wide area. Therefore, when the first vibrating body 1a vibrates around the rotation axis D1 that passes through the center of the membrane 3 and is perpendicular to the paper plane of FIG. 1, the vibrating body 1a pushes the test filling over a wide area. Therefore, it will encounter great resistance. A second vibrating body 4a that vibrates similarly is arranged above the first vibrating body 1a. Second
The vibrating body 4a consists of two cylindrical blocks 4 and 5 and a thin connecting part connecting both 4 and 5.
The vibrating body 4a is attached to the center of the membrane 6 at the connecting portion and can vibrate about a rotation axis D2 passing through the central membrane 3 at right angles to the drawing. The membranes 3 and 6 are made of elastic members and are attached to the upper and lower ends of the tube 7, and are attached to the first and second vibrating bodies 1.
a and 4a are made of a material with high rigidity.

When torque is applied to the first and second vibrating bodies 1a and 4a in the direction of the arrow shown in the figure, the first and second vibrating bodies move from the rest position before applying the torque around the rotation axis D1 or D2. Rotate. Therefore, membrane 3
Or 6 undergoes elastic deformation and applies restoring torque to both vibrators. Next, when the torque application is stopped, the vibrating bodies 1a and 4a begin to vibrate at the resonant frequency of the vibrating bodies, centering on their respective rest positions.

As is well known, the resonance frequency of the two vibrating bodies 1a and 4a is calculated by the following equation.

Here, J is the moment of inertia of the vibrating body about the rotation axis D1 or D2, and D ^* is the equivalent spring constant of the membranes 3 and 6 that function as return springs. Both vibrators are designed to have the same resonant frequency. This design can be easily realized by appropriately selecting the dimensions of the vibrating body and the membrane to which it is attached.

The outer edges of the membranes 3 and 6 are attached to the upper and lower ends of the tube 7, respectively, as described above, and both vibrating bodies 1a or 4a are oriented at 180 degrees from each other in the same plane, that is, the vibration plane.
It vibrates in opposite directions with a phase difference of °. Therefore, the torques acting on the tube 7 due to the elastic deformation of the membranes 3 and 6 are in opposite directions and therefore cancel out in the tube;
If the mass distribution is selected so that the center of gravity of both vibrating bodies is on the rotation axis D1 or D2, the two centers of gravity will not move even during vibration, and therefore the center of gravity of the entire system will remain stationary. Therefore, the tube 7 forms a vibration node of the vibration system over its entire length.

The tube 7 of the vibration mechanism is connected to the screw piece 9 through the annular membrane 8.
The above-mentioned attachment or suspension, carried out using a flexible annular membrane 8, ensures that even if the vibrations are not completely canceled out in the tube 7 and still remain, they are transmitted through the threaded piece 9 to the container. There is no transmission to the septum 100 and therefore to the container.

In the embodiment shown in FIG. 1, vibration driving devices 111, 112, 113 using electromagnetic action are used as devices for driving the vibrating bodies 1a, 4a. The device includes an exciting iron core 111 and a movable piece 11 attracted to the exciting iron core 111.
2 and the excitation coil 11 wound around the excitation core 111
3. The excitation core 111 is placed next to the tube 7 in the vibration plane, and the tube 7 and the vibrating bodies 1a and 4a are made of a non-magnetic material such as brass. Excitation core 111
has two legs extending parallel to each other, the tips of the legs penetrate holes made in the peripheral wall of the tube 7, and the masses 1 and 5 of the first and second vibrating bodies are connected to each other. It protrudes to a position 1 to 2 mm away from adjacent parts. A movable piece 112 made of a magnetically soft material, for example, low carbon steel, is provided at the portions of both vibrators 1a and 4a facing the ends of both legs of the excitation core 111.
is buried.

A coil 113 is wound around the excitation core 111,
When a pulsating direct current is passed through this coil, the two movable pieces 112 are attracted to the tips of the two legs of the exciting core 111 with a force corresponding to the current flowing through the coil 113. Therefore, the two vibrating bodies 1a and 4
a vibrates within a common plane in the direction indicated by the arrow or in the opposite direction, with a phase difference of approximately 180°, in response to a periodic torque corresponding to the direction of the excitation current flowing through the coil 113. A device using electromagnetic action is also particularly suitable for the vibration detection device. This device is fixed to the mass 1 in the radial direction on the opposite side with respect to the excitation core 111 and the tube 7 in the vibration plane.
A bar magnet 114 protrudes outward through the hole 115 of the
and a coil 116 that is electromagnetically connected to the bar magnet 114 around the externally protruding portion of the bar magnet 114.

When a DC pulse current is passed through the coil 113 to vibrate the first vibrating body 1a, the magnet 114 reciprocates within the coil 116, and an AC voltage is induced within the coil 116. Its frequency is equal to the vibration frequency of the first vibrating body 1a, and the amplitude of the AC voltage is
It is related to the amplitude of mechanical vibration of the first vibrating body 1a. The AC voltage induced in the coil 116 is amplified by an amplifier 117, converted into a pulsating DC current, and sent to the coil 113 to form a feedback system. Since the frequency of this pulsating direct current is set equal to the resonance frequency of the first and second vibrating bodies 1a and 4a, the vibration amplitude of the first and second vibrating bodies 1a and 4a and the induction generated in the coil 116 are Both voltages are maximum. In other words, the loop gain of the feedback system of this device is maximized at the resonant frequency of the mechanical vibration system, and the maximum value is designed to be 1 or more. Therefore, the vibration system naturally oscillates at the resonant frequency of the mechanical vibration mechanism, and the strength of the oscillation gradually increases. It is designed to prevent

When the rod-shaped portion 2 of the first vibrating body 1a protruding into the chamber of the container is pushed into the filling, the vibration of the first vibrating body 1a is attenuated by the braking action of the filling. The output of amplifier 117 is directed to limit value discriminator 118, the output of which is used to drive a switching device such as relay 119. The height of the filling inside the container decreases,
When the rod-shaped portion 2 of the first vibrating body 1a is exposed again from the filling, the system oscillates again, and the limit value discriminator 11
8 changes and the relay 119 returns to its original state. Since the mechanical vibration mechanism loses almost no vibration energy unless the rod-shaped part 2 is inserted into the filling, in order to oscillate the system and sustain the vibration,
Only a small amount of power is required from amplifier 117. Therefore, even the smallest attenuations that occur in the case of very light fillings can be detected and displayed or a circuit can be switched. In other words,
The filling height of extremely light fillings can also be monitored with this device.

Experimental studies have shown that a fundamental frequency of 50 Hz to 1 kHz is suitable for the device according to the invention; particularly favorable conditions are such that the fundamental frequency is several hundred Hz and the rod-shaped part 2 projects into the container. The vibration amplitude at the end is several tenths of a millimeter.

Normally, the device is installed on the wall of the container depending on the height at which the filling condition is to be monitored, but if the device is suspended from above and used at the desired height, it is possible to The height can be controlled and monitored for various values.

Embodiments of the device according to the invention, particularly of compact construction, are shown in FIGS. 3 to 6.

The apparatus shown in FIG. 3 includes a first vibrating body 10 and a second vibrating body 12 arranged coaxially with each other and at least partially spaced apart from each other in a complicated manner.
Consists of. The vibrating body 10 is a rod-shaped solid cylindrical body 14
and a hollow tubular portion 16. Note that the tubular portion 16 is used while protruding into the interior of a container (not shown). The cylindrical body 14 and the tubular portion 16 are attached to the center of the membrane 18 and can vibrate in the direction of the arrow in the figure and in the opposite direction about a pivot axis D1 extending through the center of the membrane at right angles to the figure. The ends of the tubular portion 16 that protrude into the container are flattened from the left and right sides of the figure, and when the ends of the tubular portion 16 vibrate within the container about the rotation axis D1, Since the effective area over which the edge displaces the filling in the container is large, an increased sensitivity of the device according to the invention is achieved as a result. Since the lower portion of the first vibrating body 10 is formed using a tube member, it is extremely easy to crush the flat portion. Further, the first vibrating body 10 is made of a rigid body, and the membrane 18 is made of an elastic member. Therefore, when torque is applied to the first vibrating body 10 in the direction of the arrow, the first vibrating body 10 slightly rotates from its rest position about the rotation axis D1. The rotation is caused by the rotation of the membrane 18.
This is done stably by the action of the restoring torque caused by the elastic deformation of the At this time, when the first vibrating body 10 is released into a free state, the vibrating body 10 starts vibrating around the rotation axis D1 with the rest position as the center.
The second vibrating body 12 consists of cylindrical bodies 20 and 22 and a cylindrical body 24 that connects them. Cylinder 24 has a smaller diameter than both cylinders 20 and 22 and is attached to the center of membrane 26.

The cylindrical bodies 20, 22, and 24 have through holes extending in the axial direction, and the cylindrical body 14 of the first vibrating body 10 projects into the through holes. Second vibrator 12
is a rigid body and the membrane 26 is made of an elastic material, so when appropriately excited, it rotates in the direction of the arrow and in the opposite direction about the rotation axis D2 extending through the center of the membrane 26 at right angles to FIG. vibrates.

The resonant frequencies of the first and second vibrating bodies 10 and 12 are determined by the respective moments of inertia of the vibrating bodies and the restoring torque of the membrane acting as a return spring. Therefore, by appropriately selecting the dimensions of each vibrating body 10, 12 and the corresponding membranes 18, 26,
Vibrating bodies having equal resonant frequencies can be easily manufactured.

The outer edges of membranes 18, 26 are each attached to the end of tube 28. As will be explained later, since the two vibrating bodies 10 and 12 are manufactured to vibrate in opposite rotational directions within the same vibration plane, the membrane 1
The torques caused by the elastic deformations of 8, 26 act in opposite directions on the tube 28 and are canceled out here.
The centers of gravity of both vibrating bodies 10 and 12 are rotational axes D1, respectively.
Alternatively, since the mass distribution of both is selected so as to be above D2, the two centers of gravity do not move during vibration, so the center of gravity of both vibration units as a whole also does not move. Therefore, the tube 28 forms a node in the vibration system over its entire length. The tube 28 is fixed to the screw piece 32 by an annular membrane 30 which is designed to be flexible with respect to vibrations, so that, since it is supported by the annular membrane 30, vibrations are transmitted from the vibrating bodies 10, 12 to the tube 28. Even if the vibrations are not completely canceled out and there are still residual vibrations in the tube 28, these do not reach the wall 33 of the container (not shown) via the threaded piece 32.

An electromagnetic device is suitable as the vibration drive, for which purpose a coil 34 is arranged in the upper cylinder 20 and surrounded by a tube 36 . tube 36
The pin 38, which acts as a rod-shaped body or a magnetic pole, is made of a magnetically soft material.
It is buried in the radial direction of 0. Its radial length is determined from the position where it contacts the outer tube 36 to the axial hole provided in the center of the coil 34. The pin 38 acting as a magnetic pole connects the coil 34 to the solid cylindrical body 14 of the first vibrating body 10 through a gap formed between the solid cylindrical body 14 and the solid cylindrical body 14.
guide the magnetic field formed in the The vibrating body 10 is made of a magnetically soft material at least in the area where the coil 34 is arranged, and a magnetic circuit is formed by the tube 36, the pin 38, the cylindrical body 14 of the first vibrating body 10, and the gap. . The tube 36, the pin 38, and the coil 34 constitute the vibrating mass of the upper cylindrical body of the second vibrating body, and constitute a vibration driving device. Such a double configuration allows for a smaller size and weight reduction of the device of the invention. The connecting wires of the coil 34 are led out from the vicinity of the membrane 26, that is, from the vibration nodes, so that failure of the connecting wires will not degrade the functionality of the vibration drive device.

When a pulsating direct current is passed through the coil 34, the first
The vibrating body 10 is attracted to the pin 38 at a period corresponding to the period of current fluctuation, and the two vibrating bodies 10, 12
vibrate in opposite rotational directions in a common plane of vibration. The reason is as follows. That is, the first vibrating body 10 and the second vibrating body 12 are rotatably attached to the rotation shafts D1 and D2 via the membranes 12 and 26 attached to the tube 28, respectively. As shown in FIG. 3, the rotation axis D2 is provided above the rotation axis D1, and the vibration drive device is provided above both the rotation axes D1 and D2. With this configuration, when a pulsating direct current is passed through the coil 34, the above-mentioned magnetic circuit is formed, based on the attractive force generated between the tips of the two pins 38, which act as magnetic poles, and the cylindrical body 14. The first vibrating body 10 is connected to the pin 38.
The pin 38 is attracted towards the columnar body 14. Therefore, the first vibrating body 10 is
The second
The vibrating body 12 rotates counterclockwise around the rotation axis D2. During the pulsating direct current, both vibrating bodies 10, 12 move in the opposite direction to the excitation due to the restoring forces based on the membranes 18, 26, and the next pulsating direct current causes them to move clockwise again as described above. and rotated counterclockwise. Since the resonant frequencies of both vibrating bodies 10 and 12 and the period of the pulsating DC current are set to approximately the same value as described above, the first and second
The vibration amplitude of the vibrating body gradually increases until it reaches a certain value and is maintained.

A piezoelectric ceramic element 40 is used as a vibration detection device.
(hereinafter simply referred to as piezoelectric element) is used. This element is glued onto the membrane 18 in the plane of vibration. When both vibrating bodies 10 and 12 vibrate, the membrane 18 is periodically deformed, and a force corresponding to this deformation acts on the piezoelectric element 40, so that the piezoelectric element 40 generates an AC voltage signal corresponding to the vibration amplitude and frequency of the vibration system. Send out. Instead of using the piezoelectric element 40 described above, the membrane 18
The periodic deformation of can also be detected using foil strain gauges fixed to the membrane 18. In that case, the periodic resistance changes occurring in the foil strain gauge can be electronically converted into an alternating current voltage signal, which can be used to determine the height of the filling. Both of the above vibration detection devices are
It has the advantages of requiring less space and weight, being extremely robust both electrically and mechanically, and being inexpensive. In this case, the vibration detection device of the vibrating body is mounted on a membrane 18 that projects into the container and is attached to a tubular member 16 constituting the lower part of the first vibrating body 10, which is damped when it comes into contact with the filling.
In this way, the damping effect of the filling acts directly on the vibration detection device, so that the vibrations of the first vibrating body 10 are quickly and reliably damped.

When the device enters the operating state, an electrical signal having a frequency equal to the vibration frequency of the first vibrating body 10 and an amplitude proportional to the mechanical vibration amplitude of the first vibrating body 10 is sent out from the piezoelectric element 40; The electrical signal is converted into a pulsating direct current through an amplifier 42, and the coil 3
Sent to 4. A feedback circuit is thus formed. Since the frequency of this pulsating direct current is set equal to the resonance frequency of both the vibrating bodies 10 and 12, the vibrating bodies vibrate at the maximum amplitude, and the piezoelectric element 40 sends out an electric signal of the maximum amplitude, and at this frequency, the vibrating bodies vibrate at maximum amplitude. The loop gain of the feedback circuit is then maximized. Since the loop gain is designed to be greater than 1, the system will self-oscillate at the resonant frequency of the mechanical vibration mechanism. The self-excited vibration reaches its amplitude limit when the amplifier 42 becomes overloaded. When the tubular part 16 of the first vibrating body 10, which projects into the chamber of the container, is inserted into the filling, the vibrations are damped by the consumption of energy, as described above, and the limit value downstream of the amplifier 42 is The output of the discriminator 44 changes so that the limit value discriminator 44
A switching operation is performed on the relay 46 located downstream of the switch.

If the lower end of the tubular part 16 of the first vibrating body 10 is exposed again due to a reduction in the height of the filling, the vibrating system oscillates again and before the limit value discriminator 44 switches the switch device or relay 46. return to the state of
As long as the tubular portion 16 is not inserted into the filling, the reduction in vibrational energy will be so small that only a small amount of amplifier power will be required to oscillate and maintain the system in oscillation. The vibrating system therefore responds even to very small dampings caused by, for example, very light fillings, and the depth of the filling can be determined.

FIGS. 4 and 5 show other examples of the device of the invention which are compactly constructed. FIG. 4 is a longitudinal sectional view cut along the vibration plane, and FIG. 5 is a longitudinal sectional view perpendicular to the vibration plane.

A tube-shaped first vibrating body 4 protruding into the chamber of the container
8 is flattened so that its lower end becomes wider in the vibration direction as in the embodiment shown in FIG. The membrane 50 is mounted so as to be orthogonal to the plane of the membrane 50 (when in a stationary state), and makes reciprocating vibrations in the direction of the arrow and in the opposite direction around the rotation axis D1 that extends perpendicularly to the figure through the center of the membrane 50. be able to. A second vibrating body 5 made of a solid cylindrical body
The lower free end of 2 is inserted into the upper tubular part of the first vibrating body 48 and fixed to a membrane 54 acting as a return spring in the relatively upper part of the second vibrating body 52. , reciprocating vibrations can be made in the direction of the arrow and in the opposite direction around a rotation axis D2 extending perpendicularly to the drawing at the center of the membrane 54. The outer edges of membranes 50 and 54 are attached to tube 56. By appropriately dimensioning the first and second vibrating bodies 48 and 52, they can be formed to have equal resonant frequencies. Vibrating body 4
In order to keep the center of gravity of the vibrating mechanism consisting of the membranes 50, 52, the membranes 50, 54, and the connecting tube 56 stationary without moving during vibration, vibrating bodies placed above and below the membrane 54 are required. The mass distribution of 52 must be determined appropriately.

That is, the centers of gravity of the vibrating bodies 48 and 52 do not need to coincide with the rotation axes D1 and D2, respectively. This can be clearly explained using FIG. FIG. 6 is an explanatory diagram showing only the main points of the above explanation.

In FIG. 6, the first and second vibrating bodies 48 and 52 are vibrating bodies DS ₁ that act as pendulums that vibrate around rotational axes D1 and D2 that point at vertically separated positions.
and DS ₂ . Vibrating body DS ₁ ,
Let the masses of DS ₂ be m ₁ and m ₂ respectively, and the center of gravity S ₁ ,
Assume that S ₂ is concentrated. Also, in the figure, the vibrating body
DS ₁ and DS ₂ are located at angles α ₁ and α ₂ to the right and left from the vertical line, respectively, and at this time, the center of gravity
The distances S ₁ and S ₂ swerve from the vertical line are indicated by L ₁ and L ₂ .
DS ₂ is deeply inserted into the vibrating body DS ₁ , so that the vibrating body DS ₂ has a small moment of inertia. Under such a configuration, in order for the vibrating bodies DS ₁ and DS ₂ to have the same resonant frequency as described above, the equivalent spring constant for the vibrating body DS ₂ must be different from the spring constant for the vibrating body DS ₁ . It must be formed small.

The relationship between the resonant frequency of the vibrating body, the moment of inertia, and the equivalent spring constant is given by Equation (1) above.

Also, according to what mechanics teaches, the center of gravity as shown above
The conditions for the center of gravity of the entire vibration system to remain stationary regardless of the movement of S ₁ and S ₂ are as follows.

m ₁ ×L ₁ = m ₂ ×L ₂ Therefore, for the vibrating body DS ₁ , specific values of frequency, moment of inertia, equivalent spring constant, weight of the vibrating body, distance between the center of gravity and center of rotation, and deflection angle are determined in advance. For example, values corresponding to the above-mentioned various values of the vibrating body DS ₂ are calculated. By selecting an appropriate mass distribution of the vibrating bodies DS ₁ and DS ₂ , in particular the mass of the vibrating body DS ₂ distributed on both sides of the relevant membrane, the center of gravity of the vibrating body can be adjusted so that the above conditions are maintained. can be determined. This condition is sufficient to keep the center of gravity of the vibration system consisting of both vibrators (hereinafter referred to as the overall center of gravity) stationary, but it is also sufficient to keep the tube connecting the two individual vibrators stationary. is not enough. As shown in FIG. 6, if a vibration system is formed, so that the centers of gravity S ₁ and S ₂ are spatially separated in the resting state, the centers of gravity S 1 and S ₂ will be separated during vibration. This is because S ₂ may move from its rest position and the remaining part of the oscillator may be swung in the opposite direction. This causes torque to act on the tube connecting the two individual vibrators. In order _to prevent this, the _two vibrating bodies 48,
52 must be formed in an intertwined shape. In this way, the vibration system can be formed as shown in FIGS. 4 and 5, and the device can be made more compact and inexpensive.

In the embodiments shown in FIGS. 4 and 5, the first and second vibrating bodies 48, 52 are manufactured to have equal resonant frequencies by selecting appropriate dimensions according to the conditions listed above. However, if the two vibrating bodies 48 and 52 are driven to rotate in opposite directions during operation, the torques of the two vibrating bodies 48 and 52 are canceled out by the connecting pipe 56, and the connecting pipe 56 forms a node of the vibration system over its entire length. becomes. In the embodiments of FIGS. 4 and 5, similarly to FIG. 3, the threaded piece 6 is inserted through the annular membrane 58 (FIG. 5).
Connected to 0.

A piezoelectric element is provided for generating and detecting vibration. The tube 56 is split perpendicularly to the axis of the tube 56 to accommodate the piezoelectric element 62 . The two divided parts are connected by two threaded joints 64 as shown in FIG. Fitting 6
4 are provided on the upper surface of the tube 56 at positions 180° apart on both sides of the vibrating body 52. Two separating plates 66 are inserted into the gap between the two divided sections of tube 56. Between the two parts of the divided tube 56 on both sides of the diameter of the tube 56 and on the plane of vibration, piezoelectric elements 62 each consisting of two ceramic plates are arranged, each piezoelectric transducer pair 62, 62 form. A thin metal foil 68 is inserted between each of the two piezoelectric elements 62 as a first electrode, and a second electrode is formed from two parts of the tube 56 that are separated from each other. They are electrically connected by screws 64. In this way, the two piezoelectric elements 62 of each transducer pair are electrically in parallel;
Mechanically, they are connected in series.

When an alternating current voltage is applied to one piezoelectric transducer pair 62, 62, the transducer pair deforms to become thicker and thinner at the frequency of the alternating voltage, and the first and second vibrating bodies 48, 52 Vibration in opposite directions about the respective rotation axes D1 and D2 is performed via the outer edges of the two membranes 50 and 54. The details of the vibration generation are as follows. That is, the first vibrating body 48 can rotate around the center of the membrane 50 about the rotation axis D1 provided approximately at right angles to the figure, and the second vibrating body 5
2 can rotate the center of the membrane 52 around a rotation axis D2 provided in a direction substantially perpendicular to the drawing. As described above, an AC voltage is applied to one of the piezoelectric conversion pairs, for example, the first piezoelectric conversion pair on the right side in FIG. 4, and the thickness of the piezoelectric conversion pair changes periodically. In this case, when the thickness is the thickest, the right side of the membrane 54 moves the most upwardly, and the right side of the membrane 50 moves most downwardly. At this time, since the thickness of the second electric conversion pair on the left side does not change, the left side of the membrane 54 is higher than the right side in the figure, and the left side of the membrane 50 is lower than the left side. Therefore, the first vibrating body 48 receives a clockwise torque about the rotation axis D1, and the second vibrating body 52 receives a counterclockwise torque about the rotation axis D2, and rotates in the torque direction. move. The instantaneous value of AC voltage decreases,
When the piezoelectric effect decreases, both vibrators pass their rest position and move to the maximum deviation position in the opposite direction due to the voltage applied in the opposite direction, and the above operation occurs again in the next cycle of the AC voltage. is repeated, and a state of vibration of both vibrating bodies having substantially opposite phases to each other is formed. Of course, the resonant frequencies of both vibrators must be formed so that the frequency of the applied alternating current voltage almost matches.

A second pair of piezoelectric transducers 62, 62, located on the opposite side of the tube 56, inverts the piezoelectric effect of the first pair of transducers 62, 62 and generates an alternating current depending on the frequency and amplitude of the mechanical vibrations. Sends out a voltage output signal. This output signal is amplified by an electronic amplifier 70 and sent to a first pair of piezoelectric transducers 62, 62, thus providing a feedback circuit. This circuit can continue to oscillate like a normal oscillator if the loop control is 1 or more as described above. As stated at the beginning, in this case as well, the vibration system performs self-excited vibration, and the vibrating body vibrates at the mechanical resonance frequency. If the first vibrating body 48 inserted into the container is covered with a filling, vibration damping occurs, and the third vibrating body 48
As in the case shown, a limit value discriminator 72 connected to an amplifier 70 operates to effect switching of a switch device or relay 74. When the filling height falls and the lower end of the first vibrating body 48 is exposed again, the vibrating body 48 vibrates strongly again, and the relay 74 is activated by the action of the limit value discriminator 72.
8 returns to the state before being covered with the filling material. By dividing the tube 56 and placing the piezoelectric transducer therebetween, the requirement that the entire tube 56 be the vibrational node of the system is substantially, if not completely, satisfied. Due to the high performance of the vibration system and therefore the sharpness of the resonance, the small vibration amplitude detected by a piezoelectric transducer using a piezoelectric element can be considered to be ignored, and the first Even if the vibrating body 48 is suspended from the tube 46 via the annular membrane 58 (FIG. 5), the sensitivity of detecting the height of the filling material by this device will not be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a first embodiment of the device according to the invention, FIG. 2 is a side view of a vibrating body projecting into the container, and FIG. 3 is a sectional view of a second embodiment of the device according to the invention. , FIG. 4 is a sectional view of a third embodiment of the device according to the invention, FIG. 5 is a sectional view of the third embodiment of the device shown in FIG. 4 rotated by 90 degrees, and FIG. FIG. 2 is a diagram explaining the principle of the system. DESCRIPTION OF SYMBOLS 1... Massive body, 1a... First vibrating body, 2... Rod-shaped part, 3... Membrane, 4, 5... Massive body, 4a... Second vibrating body, 6... Membrane, 7... Tube, 9... Screwed piece , 10...first
vibrating body, 12... second vibrating body, 14... cylindrical body,
16... Tubular portion, 18... Membrane, 20, 22, 23,
24... Cylindrical body, 26... Membrane, 28... Tube, 30... Annular membrane, 34... Coil, 36... Tube, 38... Pin, rod-shaped body, 42... Amplifier, 44... Limit value discriminator, 46...
Switch device, relay, 48...first vibrating body, 5
0... Membrane, 52... Vibrating body, 54... Membrane, 56... Tube, 6
2... Piezoelectric element, 70... Amplifier, 72... Limit value discriminator, 74... Relay, 100... Partition wall, 111... Excitation core, 112... Movable piece, 113... Coil, 114
... Bar magnet, 115 ... Hole, 116 ... Coil, 117
...Amplifier, 118...Relay, D1, D2... Rotation shaft.

Claims (1)

[Scope of Claims] 1. A vibration mechanism having a vibrating body configured as a vibrating rod, whose lower end is inserted into a container containing a filling and whose vibration is damped when it comes into contact with the filling; A device for detecting and detecting the height of the filling contained in the container, comprising: a display indicating the filling height of the filling in the container in response to the amplitude of the body; and a device that opens and closes at least one of the electric circuits.
In the monitoring device, the vibration mechanisms 1, 2, 3, 4, 5, 6, 7,
Two vibrating bodies 1a, arranged vertically and almost coaxially,
4a, and only the lower end of the vibrating body 1a disposed below is inserted into the container; The two vibrating bodies 1a and 4a are reciprocated at the same resonance frequency in one direction and in the opposite direction in opposite phases. vibration drive devices 111, 112, 113 that are electromagnetically excited so as to vibrate and rotate; two vibrating bodies 1a, 4a that are made of an elastic material and that vibrate as described above, each located approximately at the center; The two supporting membranes 3 and 6; The tube 7 to which the peripheral edges of the two membranes are attached; One of the two vibrating bodies 1a and 4a 1
The electric signal obtained by detecting the vibration of
Vibration detection device 114,1 that feeds back to 3
15,116,117 A filling height detection/monitoring device comprising: 2. The vibrating bodies 1a and 4a are respectively disposed at the center of the membrane 3; 6 acting as a return spring, and the outer edges of the membranes are firmly connected to each other via a tube 7. , an apparatus according to claim 1. 3 The center of gravity of each vibrating body 1a, 4a is at the center of the membrane 3;6, and the rotation axis D1;D of the vibrating body 1a, 4a is
3. Device according to claim 2, characterized in that it is on the top of the second claim. 4 Pipe 7 of vibration mechanism 1, 2, 3, 4, 5, 6, 7
is arranged by an annular membrane 8 on a threaded piece 9, which threaded piece is attached to a partition wall 100 of the container. 1. The device according to 1. 5. The device according to any one of claims 1 to 4, wherein the vibration mechanisms 1, 2, 3, 4, 5, 6, and 7 are made of a non-magnetic material. 6. The electromagnetic drive device includes an excitation core 111, an excitation coil 113 wound around the excitation core and through which a pulsating direct current is passed, and two pieces each embedded in one of the vibrators 1a and 4a and attracted to the excitation core. 6. The device according to any one of claims 1 to 5, characterized in that it consists of a movable piece 112 of. 7. The excitation core 111 has two legs arranged substantially parallel to the vibrating bodies 1a and 4a, and the free ends of the legs are embedded in one of the vibrating bodies 1a and 4a, respectively. The device according to any one of claims 1 to 6, characterized in that the device faces the movable piece 112. 8 Disposed on the opposite side of the drive devices 111, 112, 113, and includes a bar magnet 114 and at least the bar magnet 1.
According to any one of claims 1 to 5, the vibrations of the vibration mechanisms 1 to 7 are detected by an electromagnetic device comprising a coil 116 surrounding a part of the vibration mechanism 14. The device described. 9. Claim 8, characterized in that a bar magnet 114 is attached to one of the vibrating bodies 1a and reciprocates in the coil 116 when the vibrating mechanism vibrates.
The equipment described in section. 10 The voltage induced in the coil 116 of the electromagnetic device for vibration detection when the vibration mechanism vibrates is transmitted to the amplifier 11.
10. Device according to claim 6, characterized in that the device is fed as a pulsating direct current to the excitation coil 113 of the drive device via a pulsating direct current. 11 The output of the amplifier 117 is the limit value discriminator 118
11. Device according to claim 10, characterized in that it is connected to a. 12 The above-mentioned two vibrating bodies 10 and 1 arranged coaxially
2; A through hole is provided in one of 48 and 52 along its central axis, and a portion of the other vibrating body having a diameter smaller than that of the hole is inserted into the through hole. An apparatus according to claim 1, wherein: 13. Device according to claim 12, characterized in that the first vibrating body 10, which projects into the container, projects into a cavity located in the second vibrating body 12. 14. Device according to claim 12, characterized in that the first vibrating body 48, which projects into the container, has a cavity, into which the second vibrating body 52 projects. 15 Each vibrating body 10, 12; 48, 52 has a membrane 18, 26; 50, which acts as a return spring, respectively.
54, the surface of the membrane is perpendicular to the axis of the vibrating body in a resting state, and the outer edges of the membrane are firmly connected to each other via the annular bodies 28, 56. Apparatus according to claim 13 or 14. 16. It is noted that the first vibrating body 10 consists of a solid cylindrical body 14 firmly connected to a hollow cylindrical body 16, and the free lower end of said hollow cylindrical body 16 is crushed to form a flattened lower end. Characterized by
Apparatus according to claim 13. 17 The second vibrating body 12 consists of two cylindrical bodies 20 and 22 that are firmly connected to each other, and the cylindrical body has a through hole for accommodating the upper part of the solid cylindrical body 14 of the first vibrating body 10. 13. Device according to claim 12, characterized in that it comprises: 18 two cylindrical bodies 20, 22 have a smaller diameter in the center of the membrane 26 compared to the two cylindrical bodies;
And by the third cylindrical body 24 having a through hole,
18. Device according to claim 13 or 17, characterized in that they are rigidly connected to each other. 19 Upper cylindrical body 20 for electromagnetic vibration drive device
A coil 34 is built in the coil 34, and the coil is surrounded by a tube 36 forming an excitation core, which tube simultaneously forms the outer peripheral surface of the upper cylindrical body 20. The device according to item 18. 20 The upper cylindrical body 20 has at both ends of the coil 34 two rod-shaped pins 38 made of magnetically soft material arranged along the vibration plane, and the pins 38 are connected to the tube 36. , and the through hole of the cylindrical body 20 are magnetically connected in the radial direction. 21. Device according to claim 19 or 20, characterized in that at least the area of the coil 34 of the solid cylindrical body 14 of the first vibrating body 10 consists of a magnetically soft material. . 22. The device according to any one of claims 18 to 21, characterized in that the tube 36, the pin 38 serving as a magnetic pole, and the solid cylindrical body 14 form a magnetic circuit. 23 Claims characterized in that a pulsating direct current derived from an electrical signal obtained from a piezoelectric element 40 or a foil strain gauge fixed on the membrane 18 of the first vibrating body 10 is sent to the coil 34. 1st
The device according to item 8. 24 The electrical signal is sent via an amplifier 42 to a coil 34 and to a limit value discriminator 44, and a switch device 46 for detecting or monitoring the filling height in the container is downstream of the limit value discriminator 44. 24. Device according to claim 23, characterized in that: 25 The first vibrating body 48 is a hollow cylindrical body,
16. Device according to claim 14 or 15, characterized in that it is attached to the membrane 50 in its upper half and is crushed so as to form a flattened shape at its lower end. 26 The second vibrating body 52 is a solid cylindrical body,
Claim 14 or 2, characterized in that its lower end projects into the hollow cylindrical body 48.
The device according to item 5. 27. Device according to claim 26, characterized in that a solid cylinder 52 is attached to the membrane 54 in the upper half. 28 The member connecting the outer edges of the membranes 50 and 54 is a tube 56 divided into a lower part and an upper part, and two piezoelectric elements 62 are disposed facing each other between the two parts, and a piezoelectric transducer is formed. 16. Device according to claim 13, characterized in that it forms a pair 62, 62. 29 The electrical signal sent from one pair of piezoelectric transducers 62, 62 is sent via an amplifier 70 to the other piezoelectric transducer 62, 62, and a switch device 74
29. The device according to claim 28, characterized in that the limit value discriminator 72 is fed to a limit value discriminator 72 followed by a limit value discriminator 72. 30. The device according to claim 12 or 15, characterized in that the center of gravity of each vibrating body 10, 12; 48, 52 coincides with the center of the corresponding membrane 18, 26; 50, 54. . 31 Although the center of gravity of each vibrating body 10, 12; 48, 52 does not coincide with the center of the corresponding membrane 18, 26; 50, 54, it is possible to appropriately distribute the weight of both vibrating bodies 10, 12; 48, 52. Therefore, both vibrating bodies should be coaxially located so that the vibration deflection from the rest position multiplied by the mass of each vibrating body is equal, and the centers of gravity of both vibrating bodies coincide. 50, 54, so that the tubes 28, 56 connecting the two membranes 18, 26; 50, 54 remain stationary even during vibrations of the system. Apparatus according to scope 12 or 15.