JPH0113522B2 - - Google Patents

Description

[Detailed Description of the Invention] A so-called reel-type liquid level gauge that measures the liquid level from the amount of wire or tape fed out by keeping a wire or tape fixed at one end to the float at a constant tension and making the float follow the liquid level. are often equipped with an alarm sensor that automatically issues an alarm when the liquid level exceeds or falls below a certain set point. The alarm sensors currently used in retractable liquid level gauges connect a cam via a reduction gear to a rotary shaft that rotates in proportion to the liquid level in the level gauge, and the cam controls micro switches and photoelectric switches. , and other proximity switches, etc., are turned on and off (see Figure 1).

When using such an alarm sensor, it is necessary to add a reduction gear mechanism dedicated to the cam, which requires considerable cost. Additionally, in order to increase the accuracy of detecting alarm conditions, it is necessary to make the cam larger.
Installation space is an issue.

The present invention provides a roll-up type liquid level gauge developed by the applicant company with an alarm switching device for indicating the upper or lower limit of the liquid level. The present invention will be described below with reference to embodiment figures regarding an automatic liquid level gauge.

In FIGS. 2 and 3, the drum designated by reference numeral 11 has a structure having a spiral groove (not shown) on its outer periphery, and the drum shaft 12 is connected to an appropriate drive source and rotated at a low speed via a reducer. It will be done. 13a and 13b are fixed bearings, and the feed screw shaft 14 is supported on the outside of the drum in parallel with the drum shaft by these bearings 13a and 13b.
A female screw hole of a movable nut 15 serving as a slider is screwed into the screw shaft 14, and the movable nut 1
5 has a through hole fitted into a guide shaft 16 whose both ends are supported by the bearings 13a and 13b.

The nut has a dynamic pulley 1 supported by a horizontal support shaft 17a that is perpendicular to the screw shaft 14.
A pulley 8a is provided, on which a wire 9 drawn vertically from the drum can be hung. Further, a fixed pulley 18b is attached to one of the bearings 13b by a support shaft 17b, and the direction of the wire 19 from the drum is changed by 90 degrees in the direction of movement by the moving pulley 18a.
The float 20 is suspended from 8b at a fixed point. Thus, the threaded shaft 14 is connected to a suitable power transmission mechanism, such as a pulley 2 tightly fitted to the drum shaft 12, as shown in the figure.
1, a pulley 22 tightly fitted to the screw shaft 14, and a belt 23 hooked around these;
As shown in FIG. 1, the nut 15 is rotated synchronously with the drum 11 by a transmission mechanism of gears 21a and 21b, and as the nut 15 rotates, the nut 15 is threaded by the screw shaft 14 parallel to the drum. At this time, the lead of the screw shaft 14 is set so that the nut 15 is moved by one pitch of the drum's outer peripheral spiral groove with one rotation of the drum.

In the liquid level gauge as described above, the present invention sets the switch 28, which is closed when the nut 15 serving as the slider arrives, to the upper or lower limit of the liquid level.
Alternatively, it may be provided at a location corresponding to both.

The switch 28 includes a proximity switch that closes when the nut 15 arrives, a reed switch that closes the circuit by a magnet 27 provided on the nut, a limit switch that closes the circuit when pushed by the arriving nut, and other photoelectric switches. There are several, but you can select and use them as appropriate.

FIG. 7 of the embodiment shows a reed switch actuated by a magnet, and FIG. 8 shows a limit switch 28 that closes when an actuator 30 made of a magnetic material is actuated by a magnet. These are the bearings 13 of the screw shaft support.
It may be provided in a sealed guide pipe 29 installed horizontally between a and 13b to provide explosion-proof properties.

In addition, in the illustration, the reference numeral 24 indicates a housing.

In the embodiment described above, when the float rises or falls due to a change in the liquid level, the accompanying tension in the float hanging wire is detected, the drum driving source rotates forward or reverse, and the wire reaches a predetermined tension. The drum winds and unwinds the wire so that the float has a predetermined level of water relative to the liquid level, and the liquid level is measured by the forward and reverse rotation angle of the drum at that time, but the tension of the wire Mechanisms for converting a rotation angle into a liquid level value, such as a detection mechanism and a drive circuit for a motor resulting from the detection mechanism, are well known, and therefore a description thereof will be omitted.

Therefore, in the present invention, even if the drum rotates forward or backward due to liquid level fluctuations, the float moves up and down on the vertical line and does not shift laterally.

Note that the rotation angle of the drum is determined by the pulleys 18a and 18b.
This includes the length of the wire between pulley 1.
The liquid level must be calculated by correcting the change in the distance between pulleys 8a and 18b, but since the distance between both pulleys changes in proportion to the rotation angle of the drum, this correction is extremely easy. It can have a simpler mechanism than the conventional moving drum type. Further, in the present invention, a switch 28 which is closed when the nut 15 arrives is provided in a part parallel to the movement locus of the nut 15, for example, in the guide pipe 29. By setting it at a location corresponding to the upper limit, lower limit, or both, the alarm circuit can be activated to issue an alarm when the liquid level reaches the set level. In addition, the switching device has a very simple mechanism and can be easily installed, making it possible to provide a highly reliable level gauge with an alarm activation device at a much lower cost than conventional ones.

The basic idea of the wire winding mechanism is to guide the wire by a moving pulley 18a that moves laterally with the rotation of the drum at a pitch equal to the spiral groove of the drum, thereby keeping the hanging position of the wire constant. Therefore, various structures other than those of the above-mentioned embodiments are conceivable. Examples are listed below.

[Moving mechanism of pulley 18a] In the first embodiment, the screw shaft is driven by a belt, but if the screw shaft is reverse threaded, it can be driven by a gear (however, with a belt, the drum and screw (The shafts rotate in the same direction, but the gears rotate in opposite directions, so the direction of the screws must also be reversed.) Also, as shown in Figures 4 to 6, the sector female screw 26 at the tip is connected to the drum. It is also possible to move the pulley 18a by means of a slider 25 that engages with the spiral groove of the slider 25 and is threaded by a rotating drum.

[Drum driving method]

As with normal tape to float type liquid level gauges, a method using a constant torque spring, a method using a counter weight, a method using a motor, etc. can be applied.

With the constant torque spring type, there is almost no slack in the wire once it is set in the tank.
Therefore, if a pulley moving mechanism using a screw shaft as in the first embodiment is used, it can be put to practical use without providing a spiral groove on the wire winding drum.

[How to install to tank]

In the first embodiment, this instrument is installed on the tank top, but it can also be used by leading out the wire and attaching it to the tank side, as shown in Figures 9, 10, and 12. It is possible.

Further, if it is attached to the tank top as shown in FIG. 13, the fixed pulley 18b is not necessarily necessary.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a conventional example, FIG. 2 is a perspective view showing a first embodiment of the present invention, and FIG. 3 is a front view of the same.
Fig. 4 is a front view of the second embodiment, Fig. 5 is a side view of the same, Fig. 6 is a perspective view of the slider, Figs. 7 and 8 are views showing the mounting structure of the switch, Fig. 9 Figures 10, 12, and 13 are diagrams showing each embodiment of how the liquid level gauge is attached to a tank, and Figure 11 is a diagram showing a third embodiment. In the figure, 11...drum, 12...drum shaft, 1
3a, 13b...Bearing, 14...Feed screw shaft, 1
5...Slider, 16...Guide shaft, 17a, 17
b...Pulley shaft, 18a, 18b...Pulley, 1
9... Wire, 20... Float, 21, 22...
...Pulley, 23...Belt, 24...Housing, 25...Slider, 26...Sector female thread section,
27... Magnet, 28... Switch, 29... Guide pipe, 30... Actuator.

Claims (1)

[Claims] 1. A drum that winds up or unwinds a rope that suspends a liquid level sensor such as a float or displacer attached to the end of the liquid to the liquid surface by forward and reverse rotation;
A slider that is guided by a guide shaft and screwed in parallel to the drum shaft by the forward and reverse rotation of this drum.
and a movable pulley provided on this slider to change the direction of the cable from the drum parallel to the moving direction of the slider, and a liquid level sensing body suspended from the movable pulley, located on the same surface as the movable pulley. a fixed pulley for hanging a lower cable, and a switch provided on a line parallel to the movement locus of the slider that closes the circuit when the slider arrives and activates an alarm circuit. Type liquid level gauge.