CN201859000U - Capacitive liquid level transmitter - Google Patents
Capacitive liquid level transmitter Download PDFInfo
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- CN201859000U CN201859000U CN2010206149125U CN201020614912U CN201859000U CN 201859000 U CN201859000 U CN 201859000U CN 2010206149125 U CN2010206149125 U CN 2010206149125U CN 201020614912 U CN201020614912 U CN 201020614912U CN 201859000 U CN201859000 U CN 201859000U
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- liquid level
- level transmitter
- processing unit
- central processing
- circuit
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Abstract
The utility model discloses a capacitive liquid level transmitter, which comprises a capacitive sensor, a C/F (capacitance/frequency) conversion circuit, a central processing unit and an output conditioning circuit, wherein the output end of the capacitive sensor is connected with the C/F conversion circuit; the output end of the C/F conversion circuit is connected with the central processing unit; and the output end of the central processing unit is connected with the output conditioning circuit. The capacitive liquid level transmitter directly converts capacitance into a digital signal, removes the intermediate link of AD (analog-digital) conversion, realizes the high accuracy and intellectualization of liquid level measurement by utilizing the data processing advantages of the central processing unit and has the characteristics of strong anti-interference of a digital circuit, thereby improving the accuracy and stability of conversion. Simultaneously, the capacitive liquid level transmitter has simple and compact structural design, stable hardware circuits and high-efficiency software code running; and multiple anti-interference measures of softwares and hardwares enable the liquid level transmitter to have the characteristics of wide measuring media, wide measurement range, stable signal output and small temperature drift and have wide application scope.
Description
Technical field
The utility model relates to a kind of liquid level measurement device, particularly a kind of capacitance type liquid level transmitter.
Background technology
At present, the fluid level transmitter kind is numerous, mainly is divided into pressure type, float-type, condenser type by measuring principle.The capacitance type liquid level transmitter utilizes the principle of electric capacity with liquid level change, and finally is converted into standard output signals, and this transmitter has simple in structure, and the cost performance advantages of higher is used increasingly extensive.Yet the medium of measurement is subjected to environmental impact usually easily, and higher to the circuit stability dependence, causes transmitter output unstable.In recent years, many transmitters adopt two capacitive transducer measuring liquid level, and with result's contrast, thereby eliminated the influence of medium to system; Also there are many transmitters structurally to add wave breaker, reduced the liquid level jitter phenomenon, improved the transmitter performance.But this structure of transmitter complexity, the cost height has limited popularization.
Summary of the invention
The technical problems to be solved in the utility model provides a kind of capacitance type liquid level transmitter stable, simple in structure, that cost performance is high of exporting.
In order to solve the problems of the technologies described above, a kind of capacitance type liquid level transmitter of the present utility model, comprise capacitive transducer, C/F change-over circuit, CPU (central processing unit) and output modulate circuit, wherein the output terminal of capacitive transducer links to each other with the C/F change-over circuit, the output terminal of C/F change-over circuit links to each other with CPU (central processing unit), and the output terminal of CPU (central processing unit) links to each other with the output modulate circuit.
As improvement of the technical scheme, described capacitive transducer comprises urceolus and is arranged at the interior inner core of urceolus that this urceolus end is connected with flange.
As improvement of the technical scheme, the inboard and interior outer core of described urceolus is coated with tex; Described urceolus inner bottom part is provided with conical emptying mechanism; Described outer tube side wall interlocks and has some unloading ports.
As improvement of the technical scheme, described flange is provided with circuit board, and this circuit board is wherein ccontaining with C/F change-over circuit, CPU (central processing unit) and output modulate circuit; Described circuit board outer setting has shell; Described outer casing inner wall posts tinfoil.
As improvement of the technical scheme, described CPU (central processing unit) is the C8051F single-chip microcomputer of belt current output DA.
The beneficial effects of the utility model are: this capacitance type liquid level transmitter is owing to adopted said structure, used digital measuring method, directly transfer electric capacity to digital signal, saved the intermediate link of AD conversion, utilize the advantage of CPU (central processing unit) data processing, realize the high precision and intellectuality of level gauging, and had the anti-interference strong characteristics of digital circuit, thereby improved the accuracy and the stability of conversion.Simultaneously, the simple compactness of structural design, hardware circuit are stablized, the software code operation is efficient, multiple in addition software and hardware interference protection measure make this fluid level transmitter have measuring media extensively, broad quantum, stable output signal, temperature float little characteristics, range of application is wider.
Description of drawings
Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.
Fig. 1 is a structural diagrams intention of the present utility model;
Fig. 2 is a theory diagram of the present utility model;
Fig. 3 is C/F change-over circuit figure of the present utility model;
Fig. 4 is output modulate circuit figure of the present utility model;
Fig. 5 is a program flow diagram of the present utility model.
Embodiment
With reference to Fig. 1, Fig. 2, a kind of capacitance type liquid level transmitter of the present utility model, comprise capacitive transducer, C/F change-over circuit, CPU (central processing unit) and output modulate circuit, wherein the output terminal of capacitive transducer links to each other with the C/F change-over circuit, the output terminal of C/F change-over circuit links to each other with CPU (central processing unit), and the output terminal of CPU (central processing unit) links to each other with the output modulate circuit.This capacitance type liquid level transmitter is owing to adopted said structure, used digital measuring method, directly transfer electric capacity to digital signal, saved the intermediate link of AD conversion, utilize the advantage of CPU (central processing unit) data processing, realize the high precision and intellectuality of level gauging, and had the anti-interference strong characteristics of digital circuit, thereby improved the accuracy and the stability of conversion.Simultaneously, the simple compactness of structural design, hardware circuit are stablized, the software code operation is efficient, multiple in addition software and hardware interference protection measure make this fluid level transmitter have measuring media extensively, broad quantum, stable output signal, temperature float little characteristics, range of application is wider.
In the present embodiment, described capacitive transducer comprises urceolus 1 and the inner core 2 that is arranged in the urceolus 1, and this urceolus 1 end is connected with flange 3.The inboard of described urceolus 1 and inner core 2 outer walls are coated with tex, have reduced the degree of adhering to of oil, have effectively suppressed the generation of virtual liquid level.Described urceolus 1 inner bottom part is provided with conical emptying mechanism 4, has improved liquid level and has underspeeded, and has reduced bottoms level and has hoarded phenomenon.Described urceolus 1 sidewall is staggered to have some unloading ports 5, and the sensor internal liquid level and the liquid level of surveying are consistent, and has improved the sensitivity and the precision of sensor to a certain extent.
Urceolus and inner core constitute the two poles of the earth of electric capacity, analyze as calculated, obtain the formula of this electric capacity, and be as follows:
（a）
In the formula:
-------initial capacitance;
ε-------specific inductive capacity;
The h-------liquid level;
R-------urceolus radius;
The r--------inner core radius
As can be known, when specific inductive capacity was constant, electric capacity output was linear with liquid level.
Described flange 3 is provided with circuit board 6, and this circuit board 6 is wherein ccontaining with C/F change-over circuit, CPU (central processing unit) and output modulate circuit.Circuit board 6 has two, the monolithic microcomputer kernel processing unit is placed on separately on the circuit board, other devices place another piece, can not only reduce of the influence of other device like this to single-chip microcomputer, also saved simultaneously the space, this integral structure can be worked under rugged environment, especially is fit to commercial Application.Described circuit board 6 outer setting have shell 7, and described shell 7 inwalls post tinfoil, can effectively reduce electromagnetic interference (EMI).
The C/F change-over circuit be a kind of be the multivibrator of core with 555, by formula (a) as can be known, when liquid level changed, electric capacity also can be linear changing, the change of electric capacity can cause that the time of discharging and recharging changes, thereby obtains pulse signal clocklike.
C/F change-over circuit schematic diagram of the present utility model as shown in Figure 3, according to 555 multivibrator principles as can be known, capacitor discharge time is:
TL=R2(C3+C4+CX)ln2
(b)
The charging required time is:
TH=（R1+R2(C3+C4+CX)ln2 （c）
So frequency is:
f=1/(?TL+?TH)=1/(（R1+2R2）(C3+C4+CX)ln2) （d）
Therefore, the frequency of circuit output is only relevant with R and C, and as R1, R2, C3, when C4 remains unchanged, the result is relevant with Cx, and reciprocal linear with Cx.Utilize this principle,, just can measure the height of liquid level by the single-chip microcomputer pulse count.
In circuit of the present utility model, the output terminal of capacitive transducer (CX) links to each other with C/F change-over circuit (Fig. 3), and the output terminal of C/F change-over circuit links to each other with CPU (central processing unit), and the output terminal of CPU (central processing unit) links to each other with output modulate circuit (Fig. 4).
In foregoing circuit, CPU (central processing unit) is the C8051F single-chip microcomputer of belt current output DA.The C/F change-over circuit comprises 555 timers and peripheral resistance R 1 thereof, R2, capacitor C 1, C2, C3, C4, C5, inductance L 1.The output modulate circuit comprises XTR115 and peripheral capacitor C 6 thereof, C7, C8, diode D1, D2, triode Q1.In this example, CPU (central processing unit) and C/F change-over circuit are powered by XTR115 the 8th pin.
The capacitive transducer that the utility model adopted is a plug-in type cylindrical capacitance sensor, it is the size of electric capacity with the height conversion of liquid level, the C/F change-over circuit converts capacitance to pulse output again, the single-chip microcomputer acquisition pulse, filtering, and it is carried out temperature compensation and linear the correction, then by DA output, obtain 4 ~ 20MA signal of standard through the output modulate circuit.Software flow pattern as shown in Figure 5.
The above only is a preferential embodiment of the present utility model, as long as realize that with basic identical means the technical scheme of the utility model purpose all belongs within the protection domain of the present utility model.
Claims (9)
1. capacitance type liquid level transmitter, it is characterized in that comprising capacitive transducer, C/F change-over circuit, CPU (central processing unit) and output modulate circuit, wherein the output terminal of capacitive transducer links to each other with the C/F change-over circuit, the output terminal of C/F change-over circuit links to each other with CPU (central processing unit), and the output terminal of CPU (central processing unit) links to each other with the output modulate circuit.
2. capacitance type liquid level transmitter according to claim 1 is characterized in that described capacitive transducer comprises urceolus (1) and is arranged at the interior inner core (2) of urceolus (1), and this urceolus (1) end is connected with flange (3).
3. capacitance type liquid level transmitter according to claim 2 is characterized in that the inboard of described urceolus (1) and inner core (2) outer wall are coated with tex.
4. capacitance type liquid level transmitter according to claim 2 is characterized in that described urceolus (1) inner bottom part is provided with conical emptying mechanism (4).
5. capacitance type liquid level transmitter according to claim 2 is characterized in that the staggered some unloading ports (5) that have of described urceolus (1) sidewall.
6. capacitance type liquid level transmitter according to claim 2 is characterized in that described flange (3) is provided with circuit board (6), and this circuit board (6) is wherein ccontaining with C/F change-over circuit, CPU (central processing unit) and output modulate circuit.
7. capacitance type liquid level transmitter according to claim 6 is characterized in that described circuit board (6) outer setting has shell (7).
8. capacitance type liquid level transmitter according to claim 7 is characterized in that described shell (7) inwall posts tinfoil.
9. capacitance type liquid level transmitter according to claim 2 is characterized in that described CPU (central processing unit) is the C8051F single-chip microcomputer of belt current output DA.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206149125U CN201859000U (en) | 2010-11-19 | 2010-11-19 | Capacitive liquid level transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206149125U CN201859000U (en) | 2010-11-19 | 2010-11-19 | Capacitive liquid level transmitter |
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| Publication Number | Publication Date |
|---|---|
| CN201859000U true CN201859000U (en) | 2011-06-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2010206149125U Expired - Lifetime CN201859000U (en) | 2010-11-19 | 2010-11-19 | Capacitive liquid level transmitter |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102720483A (en) * | 2012-05-30 | 2012-10-10 | 中国石油大学(华东) | New method for measuring liquid level of oilwell |
| CN107449489A (en) * | 2017-08-24 | 2017-12-08 | 浙江吉利汽车研究院有限公司 | A kind of fuel level sensor and oil level measuring device for vehicle |
| CN109238400A (en) * | 2018-08-15 | 2019-01-18 | 广州视源电子科技股份有限公司 | Liquid level detection device, equipment comprising same, liquid level detection method, electronic equipment and computer readable storage medium |
| CN109443488A (en) * | 2018-10-31 | 2019-03-08 | 四川泛华航空仪表电器有限公司 | A kind of high-precision fuel quantity measurement method with temperature-compensating |
-
2010
- 2010-11-19 CN CN2010206149125U patent/CN201859000U/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102720483A (en) * | 2012-05-30 | 2012-10-10 | 中国石油大学(华东) | New method for measuring liquid level of oilwell |
| CN107449489A (en) * | 2017-08-24 | 2017-12-08 | 浙江吉利汽车研究院有限公司 | A kind of fuel level sensor and oil level measuring device for vehicle |
| CN109238400A (en) * | 2018-08-15 | 2019-01-18 | 广州视源电子科技股份有限公司 | Liquid level detection device, equipment comprising same, liquid level detection method, electronic equipment and computer readable storage medium |
| CN109443488A (en) * | 2018-10-31 | 2019-03-08 | 四川泛华航空仪表电器有限公司 | A kind of high-precision fuel quantity measurement method with temperature-compensating |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20110608 |