FI78985C - Measuring device for measuring the surface height of a silo or container. - Google Patents

Description

1 78985

Silo or tank level measuring device.

Mätanordning för att mtä ythöjden i en silo eller behallare.

The invention relates to a device for measuring the level of a silo or tank, which comprises a level sensing element, an operating device for moving the sensing element and a measuring device associated with the sensing element for determining the level detected by the sensing element.

Three different measurement principles are available for determining the surface height. These are mechanical sounding, ultrasonic echo based measurement and are sometimes used to weigh the entire silo or tank. The latter solution is expensive and is not suitable for shared, interconnected silos or larger tanks or silos. Ultrasonic echo cancellation is unreliable if the surface to be measured is not flat or planar. Known mechanical level probes are not mechanically durable under operating conditions where they are subjected to dust and operational stresses. A sonar feed extending over the entire height range to be measured, eg 10 m long, is not durable. If the sonar remains in the down position, the material flow may trap it due to the thickening at the end of the sonar.

The object of the invention is to provide a simple and reliable level measuring device with which, based on a kind of mechanical sounding, level measurement can be performed at sufficiently frequent intervals with respect to

This object is achieved by the invention on the basis of the features set out in the appended claims.

In the following, the invention will be described in more detail with reference to the accompanying drawing 2 78985, in which Fig. 1 shows the structural principle of the measuring device according to the invention and Fig. 2 shows the operating disc belonging to the measuring device according to Fig. 1 and its different operating steps.

Figure 3 shows a general block diagram of a measuring device according to the invention.

The level sensing member is a halter or a chain lf, the upper end of which is attached to a pin 7 in the vicinity of the circumference of the disc 5. The disc 5 can be rotated by a rotating device 6. One revolution of the disc 5 corresponds to one measurement period, the steps of which will be explained later. Below the fixing pin 7 at 2, there is a runway branch 4 attached to the runway 1, the upper end of which is fixed to the electronic scale 10. The length of the runway branch 4 is chosen so that when the pin 7 is in its upper position the runway branch 4 remains loose. When the pin 7 is inside the area oc marked in Fig. 2, the halter 1 and the halter branch 3 are supported by the pin 7. Instead, when the pin 7 is outside the angle 0C, the halter 1 and the halter branch 4 are supported by the scale 10.

At the beginning of the measuring period, the pin 7 is in its upper position. The disc 5 starts rotating at a constant speed, which is e.g. 6 s / revolution. While the pin 7 is still in the angular range o (inside, the measuring device is tare in connection with the amplifier 11 connected to the balance 10. The tare eliminates the effect of weight and other factors of the branch chain 4 on the measurement result. About 3 seconds after the start of the measurement period The balance 10 weighs the weight F ^ of the free length L of the rune 1. The measurement message corresponding to the weight is confirmed by the amplifier 11 and stored in the memory 12, where the measurement message is available until the contents of the memory are changed to the new 3 78985 measured values. the measurement message based on the weight of the length L is inverted to the height H, the measurement message from the memory 12 is connected to the inverting input of the amplifier 13, the minimum value of the weighing measurement message having the amplifier 13 output at its maximum value and the weighing measurement message issään. The amplifier 13 controls a display device 14, which may be a numeric display, a hand display, a plotter or the like. The output of the amplifier 13 can also control an alarm device, an automatic charge trigger, etc.

During the rotation phase II indicated in Fig. 2, the pin 7 rises again in the angular range <*. inside and as the pin 7 enters the sensing member 8, the disc 5 stops waiting for the start of a new measuring period. The interval between measuring periods can be selected to the desired length depending on the application, the last measured level information is in the memory 12 until it is replaced by new information.

By rotating the disc 5 and arranging the branches 3 and 4 of the rune 1, it is ensured that at the moment of measurement the lower end of the rune 1 rests freely on the material surface 9 and the material does not cause traction in the rune 1. Instead of the rotating disc 5, it is of course also possible to use a drive which moves vertically up and down.

The invention is not limited to the embodiment described above. The operation of the measuring device can also be reversed, so that the tare of the measuring device is performed in the lower position of the pin 7 (end of step I) and weighing is performed in the upper position of the pin 7 (end of step II, in the region oc). weight, without the 4 weights of the leg involved in both tare and weighing. The new level information is recorded in step 12 in step III.

Claims (2)

4,78985 A device for measuring the level of a silo or tank, comprising a halter or chain (1) acting as a level sensing member, the length of which extends over the area to be measured and the upper end of which is fixed by a fastening member (7) to a drive device (5, 6) movable over a distance which is only a small part of the whole range of height to be measured, in addition to which the measuring device comprises a weight measuring device (10) arranged to weigh the weight of the halter or chain (1) and measuring electronics (11-14) giving the scale (10) the weight-based level reading, characterized in that the halter or chain (1) is provided with a leg (4) attached to the weight measuring device (10) and the length of the leg (4) selected so that said fastening member (7) is in its upper position , the weight measuring device (10) weighs only the weight of said leg (4) and the fastening member (7) moves a short distance downwards (<*), press the measuring device weighs the combined weight of said leg (4) and the free-hanging part of the halter or chain downstream of its attachment point (2). Level measuring device according to Claim 1, characterized in that the drive device comprises a rotatable disc (5), to the fastening element (7) in the vicinity of the circumference of which the upper end of the rune or chain (1) is fastened.