CN204944604U - High precision limnimeter - Google Patents

Abstract

The utility model relates to the technical field of water level gauges, and discloses a high-precision water level gauge, which includes a base, a guide rail and a linear displacement sensor. on the moving block; the moving block is connected with a measuring rod, and the lower end of the measuring rod has a stylus for reciprocating contact with water; the linear displacement sensor is electrically connected to control the movement of the moving block and is realized by reading the relative displacement data of the linear displacement sensor Control board for water level measurement. By controlling the main board to control the moving block to move up and down, the stylus touches the water up and down reciprocally, and the linear displacement sensor also moves up and down in a straight line. The control board directly realizes the measurement of the water level by reading the relative displacement of the linear displacement sensor; because the control board In this way, the value of the water level can be obtained directly without conversion calculation, which greatly improves the accuracy of measurement.

Description

High precision water level gauge

technical field

The utility model relates to the technical field of water level gauges, in particular to a high-precision water level gauge.

Background technique

The water level meter is a necessary measuring instrument in the physical model test of Sangong. According to the way the instrument perceives the water surface, it can be divided into three types: submerged type, vibrating water-touching type and non-water-touching type.

The non-water-touching type water level gauge has not yet met the practical requirements in terms of cost performance. The submerged type is often affected by various drifts in actual operation, and its measurement accuracy is difficult to meet the requirements. Therefore, the vibration-touching water level meter is generally used at present.

Vibrating water-touching water level gauges must use linear displacement-electricity converters, while rotary angular displacement converters, such as synchronous motors or code disc water level gauges, require a set of high-precision linear-angular displacement mechanical conversion devices such as screw rods etc. In this way, for the water level gauge, such a structure directly affects the comprehensive indicators of the water level gauge's water level conversion linearity, tracking speed, mechanical life and instrument structure, and, for the water level gauge, its ability to measure water level changes The accuracy is also low, and it is difficult to meet the actual needs.

Utility model content

The purpose of the utility model is to provide a high-precision water level gauge, aiming to solve the problem of low accuracy in measuring water level changes existing in the water level gauge in the prior art.

The utility model is realized in this way. The high-precision water level meter includes a base, a guide rail and a linear displacement sensor. The guide rail is vertically connected to the base, and the guide rail is movably connected with a A moving moving block, the linear displacement sensor is connected to the moving block; the moving block is connected with a measuring rod vertically extending downwards, and the lower end of the measuring rod has a measuring needle for reciprocating contact with water; The linear displacement sensor is electrically connected with a control board for controlling the movement of the moving block and realizing water level measurement by reading the relative displacement data of the linear displacement sensor, and the control board is electrically connected with the probe.

Further, the water level gauge includes a vertical bar, the vertical bar is vertically connected to the base, and a scale surface is formed on the side wall of the vertical bar; the linear displacement sensor includes a The scale grating on the scale surface and the reading head, the reading head is connected to the moving block and arranged on the front side of the scale surface, the reading head includes an infrared photoelectric element, a square wave shaper and an indicating grating, the The indicator grating is arranged opposite to the scale grating, and there is a gap between the two; the reading head is electrically connected to the control main board, and the control main board reads the relative displacement data of the reading head to realize Water level measurement.

Further, a zero point window is formed in the scale grating and the indicating grating respectively.

Further, the control board has frequency modulation and phase-locked loop elements for shortening the response time of the stylus entering water.

Further, the control board includes a water touch trigger, and the water touch trigger is electrically connected to the probe and the control board respectively.

Further, the upper end of the vertical bar is provided with an upper limit switch for limiting the reading head to move towards the limit position, and the lower end of the vertical bar is provided with a digital lower limit switch for limiting the reading head to move downward to the limit position switch, the upper limit switch and the digital lower limit switch are respectively electrically connected to the control main board.

Further, the guide rail passes through the moving block, and the high-precision water level gauge includes a guiding structure for guiding the movement of the moving block.

Further, the guide structure includes a guide block and a guide rod arranged on the base, the guide rod is vertically arranged, and a guide groove is provided in the guide rod, and the guide groove is arranged along the guide The length direction of the rod is extended; the side of the moving block protrudes outward to form the guide block, and the guide block is movably placed in the guide groove.

Further, the high-precision water level gauge includes a motor controlled by the control element and a belt transmission structure. The belt transmission structure includes a synchronous wheel and a synchronous belt. The output shaft of the motor is connected to the synchronous wheel. The moving block is connected to the timing belt.

Further, the upper end of the measuring rod is connected to the moving block, the lower end of the measuring rod extends downwards, and moves through the base, and the measuring needle is located below the base.

Compared with the prior art, in the water level gauge provided above, the moving block is controlled to move up and down by controlling the main board to realize the up and down reciprocating touch of the probe, and the movement of the moving block drives the linear displacement sensor to move up and down in a straight line. In this way, The control board can directly measure the water level by reading the relative displacement of the linear displacement sensor; since the linear displacement data obtained by the control board is not the circular rotation data in the prior art, in this way, no conversion calculation is required , you can directly obtain the value of the water level, greatly improving the accuracy of measurement.

Description of drawings

Fig. 1 is a schematic diagram of a front view of a high-precision water level gauge provided by an embodiment of the present invention;

Fig. 2 is the second schematic diagram of the front view of the high-precision water level gauge provided by the embodiment of the utility model;

Fig. 3 is a schematic diagram of the output signal sequence of the linear displacement sensor provided by the embodiment of the present invention;

Fig. 4 is a schematic diagram of the circuit control of the high-precision water level gauge provided by the embodiment of the utility model.

detailed description

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

The realization of the utility model is described in detail below in conjunction with specific embodiments.

Shown with reference to Fig. 1 to Fig. 4, is the preferred embodiment that the utility model provides.

The high-precision water level gauge provided in this embodiment is used for measuring the water level and the change of the water level of the river.

The water level gauge includes a base 101, a guide rail 105, a control board 104 and a linear displacement sensor, wherein the base 101 is used as a supporting platform for the entire water level gauge, and the guide rail 105 is connected to the base 101 in a vertical arrangement, and the lower end of the guide rail 105 is connected to On the base 101, the upper end extends vertically upwards; on the guide rail 105, a moving block 106 is connected, and the moving block 106 can move up and down along the guide rail 105, and the linear displacement sensor is connected on the moving block 106, like this, along with The moving block 106 moves up and down along the guide rail 105, and the linear displacement sensor can also move up and down.

In this embodiment, the moving block 106 on the guide rail 105 is also connected with a measuring rod 110, the measuring rod 110 is vertically arranged, its upper end is connected to the moving block 106, and its lower end extends downwards, and at the lower end of the measuring rod 110 A measuring needle 111 is formed, so that when the moving block 106 moves up and down along the guide rail 105, the entire measuring rod also moves up and down thereupon, and when the measuring needle 111 contacts the water surface, the control board 104 controls the moving block 106 to move upwards, when After the probe 111 leaves the water surface, the moving block 106 moves downward again, and so on.

The above-mentioned moving block is controlled to move up and down by the control board, and the probe of the measuring rod and the linear displacement sensor are also electrically connected to the control board. The measurement of the water level is realized by reading the relative displacement of the linear displacement sensor.

In the water level gauge provided above, the control board controls the moving block to move up and down to realize the up and down reciprocating touch of the probe, and the movement of the moving block drives the linear displacement sensor to move up and down in a straight line. In this way, the control board reads the linear displacement The relative displacement of the sensor can directly realize the measurement of the water level; since the linear displacement data obtained by the control board is not the circular rotation data in the prior art, in this way, the water level can be obtained directly without conversion calculation value, greatly improving the accuracy of the measurement.

In this embodiment, the water level gauge also includes a vertical rod 108, the vertical rod 108 is connected to the base 101, and is vertically arranged, so that the vertical rod 108 and the guide rail 105 are adjacently arranged in parallel, and the lower end is connected to the base 101. , the upper end extends vertically upwards.

The linear displacement sensor includes a scale grating 109 and a reading head 107, wherein a scale surface is formed on the side wall of the vertical bar 108, and the scale surface extends along the length direction of the vertical bar 108, and the scale grating 109 is formed on the vertical bar 108. on the scale surface, and extend along the length direction of the vertical bar 108, that is, extend along the vertical direction; the reading head 107 is arranged on the front side of the scale surface of the vertical bar 108, which is electrically connected to the control board 104, and Connected to the moving block 106 and move up and down as the moving block 106 moves, the reading head 107 includes an infrared photoelectric element, a square wave shaper and an indicating grating, wherein the indicating grating and the scale grating 109 are arranged facing each other, and the two There is a gap between them.

In addition, a zero point window is formed in the scale grating 109 and the indicator grating respectively, so that when the two zero point windows coincide, a unique zero point pulse signal RI within the full range will be generated.

In this embodiment, when the moving block 106 moves up and down along the guide rail 105, the reading head 107 and the measuring rod 110 also move up and down accordingly, and when the measuring needle 111 contacts the water surface, the control board 104 controls the moving block 106 to move upwards, After the measuring needle 111 leaves the water surface, the moving block 106 moves downward again, and so on.

According to the principle of geometrical optics, in the process of light linear propagation, when the light passes through the two superimposed gratings, such as the above-mentioned scale grating 109 and the indicator grating, the connection line of the intersection of the light-shielding stripe or the light-transmitting stripe forms a light-transmitting bright Lines, and the intersection of the shading stripes and the light-transmitting stripes form an opaque dark line. These bright and dark lines are called Moiré fringes. The width and trigonometric function characteristics of the Moiré fringe signal are adjusted by the angle between the grid lines. .

Taking the axial direction of the scale grating 109 as x and the vertical direction as y, the Moiré fringe equation is obtained:

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; ctg\&theta;</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; kd</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}$

In the formula: each k value corresponds to a stripe.

The slope of the Moiré fringes is:

$\mathrm{<span\; class="notranslate">\; tg\&epsiv;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; ctg\&theta;</span>}$

The pitch of the moiré fringes is:

$\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; d</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>}}$

It can be seen from the above that the Moiré fringes formed when the scale grating 109 and the index grating are superimposed are formed by clusters of parallel lines with a fringe slope of tgε and a fringe spacing of W.

When the θ angle is small, the moiré fringes are roughly perpendicular to the direction of the grating lines, and W>>d, that is, the moiré fringe spacing has an amplifying effect on the grating pitch, which is suitable for infrared photoelectric elements whose diameter is much larger than the grating pitch Very beneficial.

When the reading head 107 moves relatively along the axis of the scale grating 109, the infrared photoelectric element generates Sin sine and Cos cosine signals, which pass through the square wave shaper to output A and B two-way electrical pulse square wave signal sequences with a phase difference of 90°. When the reading head 107 moves one grating pitch relative to the scale grating 109, a square wave pulse with a directional characteristic signal is output, and the relative displacement of the reading head 107 can be obtained through the calculation of the pulse signal by the control board 104 . A zero point window is also engraved on the scale grating 109 and the index grating scale surface. When the two windows are completely overlapped, the only zero point pulse signal RI in the full range will be generated. With RI as the coordinate origin, the linear displacement sensor becomes a one-dimensional coordinate measurement system:

Reading head 107 coordinates x = grid pitch d × ∑ (± square wave pulse number)

When the reading head 107 moves in the positive direction, the A square wave pulse is 90° ahead of the B square wave pulse, and when the reading head 107 moves in the reverse direction, the A square wave pulse lags behind the B square wave pulse by 90°. Using double electronic subdivision, that is, using square wave signal edge to trigger counting, two triggers can be generated within one grating pitch, and the resolution of the linear displacement sensor with a grating pitch of 0.02mm is increased to 0.01mm. The measurement principle of the incremental grating digital encoder has been explained above, and it is intuitive and appropriate to directly measure the water level change with it.

In actual operation, when the water level gauge is turned on each time, the reading head 107 moves upwards and then moves downwards. Make the scale grating 109 coincide with the zero point window of the indicating grating, that is, after finding the zero point RI, the water level gauge enters the tracking working mode in which the probe 111 reciprocates up and down and touches the water repeatedly, and picks up the water level value every time the probe 111 touches the water , that is, the control board 104 calculates the output signal of the reading head 107 to obtain the relative displacement of the reading head 107 moving up and down, and then realizes the measurement of the water level.

Using metering grating technology in the water level gauge has the following advantages:

1) Both the scale grating 109 and the indicator grating are high-precision optical devices, and the marking accuracy can reach ±10μm/m, which solves the problems of high precision and strong interference resistance of the water level gauge;

2) A non-contact structure is adopted between the scale grating 109 and the indicating grating, which greatly prolongs the service life;

3) The Moiré fringe signal is formed by 125 grid lines, and the marking error or other leakage of individual grid lines has little influence on the position and shape of the entire Moiré fringe:

Standard deviation of fringe position = standard deviation of grid line position

4) The coordinate calculation adopts pulse phase detection technology and related analysis technology, which has strong anti-mechanical shaking ability;

5) Using subdivision technology to improve the resolution, under the same accuracy, a larger error tolerance rate can be obtained.

In addition, in the control board 104, there are frequency modulation and phase-locked loop components, so that the reaction time of the probe 111 of the measuring rod 110 entering the water can be greatly shortened, and the influence and false alarm of the surface tension of the water on the probe 111 can be eliminated. As soon as the stylus 111 touches the water surface, the control board 104 controls the moving block 106 to move upward quickly, so that the stylus 111 is out of contact with the water; Moving down until the probe 111 is in contact with the water, such a reciprocating operation can not only accurately measure the water level, but also reduce the influence of the reaction time between the probe 111 and water on the measurement accuracy.

In this embodiment, the scale grating 109 and the indicator grating are respectively engraved with a plurality of parallel and equidistant 0.01 mm wide light-shielding stripes and light-transmitting stripes. Of course, according to actual needs, the widths of the light-shielding stripes and the light-transmitting stripes can also be other values, and are not limited to the above-mentioned 0.01 mm.

When the water level gauge is working normally, the scale surface of the indicating grating and the scale grating 109 are kept parallel at a gap of 0.02 mm to 0.05 mm, and the scale grating 109 and the indicating grating are arranged obliquely, and a small angle θ is maintained between them.

In this embodiment, the control board 104 includes a water touch trigger, which is electrically connected to the probe 111 of the measuring rod 110, which can shorten the reaction time of the probe 111 entering water; the control board 104 also has a communication element, which can be used to for communicating with external devices.

Specifically, the water level gauge also has a keyboard and a display. The control board 104 adopts STM32F103 with ARM7 core, and the operating frequency of the system is increased to 72MHz. The purpose is to reduce the number of components as much as possible, make hardware software and improve operating efficiency. The control board 104 is responsible for communication, keyboard command, display, motor 102 control, discrimination of the displacement of the reading head 107 of the linear displacement sensor, coordinate calculation, water level value picking and linear displacement sensor fault diagnosis. In order to minimize hardware overhead, according to the principle of hardware software, the linear displacement sensor pulse count adopts signal edge hardware trigger, software filtering, direction judgment and addition and subtraction operations.

The accuracy of the water level meter is not only affected by the resolution of the linear displacement sensor and the operation and processing of the pulse signal, but also by the water touch trigger. In the design of this water level gauge, the water-touching trigger adopts the method of water-touching frequency conversion and phase-locked loop frequency discrimination to measure the water-touching signal of the probe 111. This design can effectively suppress the false triggering caused by the above-mentioned water body interference and avoid The water level gauge is not working properly.

The linear displacement sensor provided in this embodiment is a grating encoder, of course, the linear displacement sensor may also be other kinds of encoders, or other sensors that can realize linear displacement detection.

In this embodiment, the guide rail 105 is arranged on the side of the vertical bar 108, and the moving block 106 is connected to the side of the reading head 107, so that when the moving block 106 moves up and down and drives the reading head 107 to move up and down, avoid moving Block 106 acts between the readhead 107 and the vertical rod 108 .

In addition, an upper limit switch is arranged on the upper end of the vertical bar 108, and the upper limit switch is electrically connected with the control board 104, so that when the reading head 107 moves upwards, when it touches the upper limit switch, it will face downward. Movement, that is, the limit position to ensure that the reading head 107 moves upward.

A digital lower limit switch is provided at the lower end of the vertical rod 108, and the digital lower limit switch is electrically connected to the control board 104, which can limit and position the limit position of the reading head 107 moving downward.

In this embodiment, the guide rail 105 passes through the moving block 106 , so that the moving block 106 can move up and down along the guide rail 105 . In addition, in order to further ensure the guidance of the movement of the moving block 106 , in this embodiment, the water level gauge further includes a guiding structure for guiding the movement of the moving block 106 .

Specifically, the guide structure includes a guide rod and a guide block arranged on the base 101, the guide rod is vertically arranged, and a guide groove is provided in the guide rod, and the guide groove extends along the length direction of the guide rod, It is also vertically arranged; the side of the moving block 106 protrudes outwards to form the above-mentioned guide block, which is movably placed in the guide groove, and when the moving block 106 moves up and down, the guide block can move up and down along the guide groove , so as to guide the movement of the moving block 106 .

In this embodiment, the water level gauge further includes a power element, which is used to drive the moving block 106 to move up and down along the guide rail 105 , thereby driving the reading head 107 to move up and down. The power element is electrically connected to the control board 104 , so that the control board 104 controls the operation of the power element and further controls the movement of the moving block 106 .

Specifically, the power element includes a motor 102 and a belt transmission structure, and the belt transmission structure includes a synchronous wheel and a synchronous belt 112, wherein the motor 102 is connected to the control board 104, and the operation is controlled by the control board 104, and the output shaft of the motor 102 is connected to the belt drive The synchronous wheel of structure is connected, is used to drive synchronous wheel to rotate, and synchronous belt 112 is connected on the synchronous wheel, is driven to move by synchronous wheel, and mobile block 106 is connected with synchronous belt 112, and like this, by the movement of synchronous belt 112, drives mobile block 106 up and down movement.

In this embodiment, the upper end of the measuring rod 110 is connected to the moving block 106, and the measuring rod 110 passes through the base 101 and extends downward, and the measuring needle 111 is placed under the base 101, so that when the moving block 106 moves , the measuring rod 110 also moves through the base 101 , so that the base 101 can guide the measuring rod 110 .

In the actual measurement process, it is necessary to fix the position of the water level meter. In this embodiment, a plurality of mounting feet are connected to the base 101. Extended arrangement, in this way, when the water level gauge needs to be fixedly installed, the mounting feet can be directly connected with the external structure, so that the entire water level gauge can be fixed.

In addition, the control board 104 is arranged on the base 101, and a panel 103 is arranged on the base 101. The panel 103 is arranged on the outside of the control board 104 and is arranged opposite to the control board 104. During the control operation, the control board 104 can be operated by operating buttons on the panel 103, which can protect the control board 104 and is convenient to operate.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model shall be included in this utility model. within the scope of protection of utility models.

Claims (10)

1. High-precision water level gauge, it is characterized in that, comprises base, guide rail and linear displacement sensor, and described guide rail is vertically connected on described base, and described guide rail is movably connected with moving up and down along described guide rail. A moving block, the linear displacement sensor is connected to the moving block; the moving block is connected with a measuring rod extending vertically downwards, and the lower end of the measuring rod has a measuring needle for reciprocating contact with water; The linear displacement sensor is electrically connected with a control board for controlling the movement of the moving block and realizing water level measurement by reading the relative displacement data of the linear displacement sensor, and the control board is electrically connected with the probe. 2. The high-precision water level gauge according to claim 1, wherein the water level gauge comprises a vertical rod, and the vertical rod is vertically connected to the base, and the side wall of the vertical rod A scale surface is formed; the linear displacement sensor includes a scale grating formed on the scale surface and a reading head, the reading head is connected to the moving block and is arranged on the front side of the scale surface, and the reading head The head includes an infrared photoelectric element, a square wave shaper and an indicator grating, the indicator grating is arranged opposite to the scale grating, and there is a gap between the two; the reading head is electrically connected to the control board, and the The control board realizes the water level measurement by reading the relative displacement data of the reading head. 3. The high-precision water level gauge according to claim 2, characterized in that zero windows are respectively formed in the scale grating and the indicating grating. 4. The high-precision water level meter as claimed in claim 2, characterized in that, there are frequency modulation and phase-locked loop components for shortening the response time of the probe entering water in the control board. 5 . The high-precision water level gauge according to claim 2 , wherein the control board includes a water-touch trigger, and the water-touch trigger is electrically connected to the probe and the control board respectively. 6 . 6. The high-precision water level gauge according to any one of claims 2 to 5, wherein the upper end of the vertical rod is provided with an upper limit switch for limiting the reading head towards the limit position of movement, and the vertical rod The lower end of the upper end is provided with a digital lower limit switch for limiting the downward movement limit position of the reading head, and the upper limit switch and the digital lower limit switch are respectively electrically connected to the control main board. 7. The high-precision water level gauge according to any one of claims 2 to 5, wherein the guide rail passes through the moving block, and the high-precision water level gauge includes a guide rail for guiding the moving block Mobile guide structure. 8. The high-precision water level gauge according to claim 7, wherein the guide structure comprises a guide block and a guide rod arranged on the base, the guide rod is arranged vertically, and the guide rod A guide groove is provided in the rod, and the guide groove extends along the length direction of the guide rod; the side of the moving block protrudes outward to form the guide block, and the guide block is movably placed in the guide groove middle. 9. The high-precision water level gauge according to any one of claims 1 to 5, characterized in that, the high-precision water level gauge includes a motor and a belt drive structure controlled by the control element, and the belt drive structure includes a synchronous wheel and a synchronous belt, the output shaft of the motor is connected to the synchronous wheel, and the moving block is connected to the synchronous belt. 10. The high-precision water level gauge according to any one of claims 1 to 5, wherein the upper end of the measuring rod is connected to the moving block, the lower end of the measuring rod is extended downwards, and is movable through through the base, the stylus is located below the base.