CN216770704U - Ultrasonic oil consumption instrument - Google Patents
Ultrasonic oil consumption instrument Download PDFInfo
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- CN216770704U CN216770704U CN202120714798.1U CN202120714798U CN216770704U CN 216770704 U CN216770704 U CN 216770704U CN 202120714798 U CN202120714798 U CN 202120714798U CN 216770704 U CN216770704 U CN 216770704U
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Abstract
An ultrasonic oil consumption meter. Aiming at the characteristics of various measuring methods, the utility model provides the fuel consumption meter for measuring and calculating the fuel flow by applying the time difference method of ultrasonic waves, in order to more accurately detect the fuel economy of an automobile and provide the portability of fuel consumption detection. The ultrasonic oil consumption meter comprises a main circuit chip, a power supply module, a data storage module and a data transmission module, wherein the main circuit chip is connected with an analog circuit module, a clock circuit, a display module, a keyboard module, the data storage module and the data transmission module; the analog circuit module is connected with a group of ultrasonic transducers, and the clock circuit is connected with a clock; the analog circuit module comprises a transmitting/receiving conversion circuit, a signal receiving and processing circuit and an ultrasonic transmitting circuit, wherein the ultrasonic transmitting circuit transmits signals to the transmitting/receiving conversion circuit, and the transmitting/receiving conversion circuit transmits the signals to the signal receiving and processing circuit; 2 ultrasonic transducers are arranged on the main oil way, and 2 ultrasonic transducers are arranged on the oil return way. The utility model can accurately measure the automobile fuel flow.
Description
Technical Field
The utility model relates to an ultrasonic oil consumption meter.
Background
The existing automobile oil consumption detection method comprises a direct measurement method and an indirect measurement method. The direct measurement method measures the volume or mass of the fuel consumed by the automobile within a certain time or a certain mileage to obtain the fuel consumption of the automobile, and comprises a volumetric method, a mass method (a weight loss method) and the like. The method needs to connect the oil consumption meter in series with a fuel supply system of the engine, so that the method has safety problems (pollution and flammability caused by volatilization of gasoline); the oil consumption meter is connected in series into an oil way, so that the supply of fuel oil of an engine and the test precision of the fuel oil consumption can be influenced; meanwhile, the installation and connection of the oil consumption meter are very inconvenient; the installation and measurement process is relatively long. Indirect measurement methods, i.e., non-resolution measurement methods, include carbon balance methods, ultrasonic methods (measuring volume flow), and the like.
Among the indirect measurement methods, the commonly used measurement method based on the measurement principle is as follows: the time difference method (propagation velocity difference method), the doppler method, the correlation method, the beam offset method, the noise method, the vortex method, the flow velocity-liquid level method, and the like, and various methods have respective characteristics in flow measurement, and which type of ultrasonic flow meter can be selected according to a measured fluid, a precision requirement, and the like. The most common are the time difference method (propagation velocity difference method) and the doppler method. The doppler method is not easily affected by the state parameters of the fluid, but its measurement accuracy is affected by the size and concentration of solid particles, so it is mainly applied to the measurement of uneven fluid flow with low accuracy requirement and more particles and impurities, and it is difficult to obtain flow rate in clean fluid by the doppler method.
The evaluation of the fuel economy of automobiles in the automobile industry is generally determined by measuring the fuel consumption of an engine, which is usually measured by a fuel consumption meter. By using the fuel consumption meter to detect the change of the fuel consumption of the automobile in use, the technical conditions of a fuel system, an engine and the whole automobile can be diagnosed, the fuel economy of the automobile can be accurately detected, the use cost of the automobile can be reduced, the petroleum resource can be saved, and the purpose of saving energy can be achieved.
The ultrasonic flow measurement is classified into a time difference method, a doppler method, a correlation method, a noise method, a beam offset method, a spatial filtering method, and the like according to the principle, and the time difference method is most widely used. The time difference method ultrasonic flow detection is mainly used for measuring pure fluid with bubble and impurity content not more than 3%, the measuring circuit is simple, advanced technologies such as signal automatic tracking and temperature automatic compensation are adopted, and the device has the characteristics of stable performance, accurate and reliable metering, high instrument operation and test precision, convenience in installation and use, wide measuring range and the like. A fuel consumption detecting instrument based on an ultrasonic technology is a novel fuel consumption detecting instrument which measures fuel flow by utilizing an ultrasonic flowmeter technology and obtains fuel consumption conditions through a calculating circuit. The ultrasonic flowmeter has the characteristics of no disturbance of a flow field, no movable component, no pressure loss, high measurement precision, stable and reliable performance, wide measurement range and the like, and is widely applied to the measurement of liquid and gas.
Therefore, on the basis of analyzing and comparing various basic principles of ultrasonic flow measurement, aiming at the characteristics of various measurement methods, the utility model provides the fuel consumption meter for measuring and calculating the fuel flow by applying the time difference method of ultrasonic waves.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide an ultrasonic oil consumption meter.
The above purpose is realized by the following technical scheme:
an ultrasonic oil consumption meter comprises a shell, a main circuit chip, an analog circuit module, a printer, a keyboard module, a display module, a data storage module, a data transmission module, a clock circuit, a clock, a storage grid, a voltage-stabilized power supply, a group of ultrasonic transducers and a group of clamping mechanisms for mounting the ultrasonic transducers;
a main circuit chip, an analog circuit module, a printer, a storage grid, a voltage-stabilized power supply, a clock circuit, a display module, a keyboard module and a data storage module are arranged in the shell;
the main circuit chip is connected with the analog circuit module, the clock circuit, the display module, the keyboard module, the data storage module and the data transmission module; the analog circuit module is connected with a group of ultrasonic transducers, and the clock circuit is connected with a clock;
wherein,
the analog circuit module comprises a transmitting/receiving conversion circuit, a signal receiving and processing circuit and an ultrasonic transmitting circuit, wherein the ultrasonic transmitting circuit transmits signals to the transmitting/receiving conversion circuit, and the transmitting/receiving conversion circuit transmits the signals to the signal receiving and processing circuit; the signal receiving and processing circuit comprises an ultrasonic signal receiving and amplifying circuit, a filter circuit, a sampling gating circuit and a zero-crossing comparison circuit;
the group of ultrasonic transducers comprises an ultrasonic transducer A, an ultrasonic transducer B, an ultrasonic transducer C and an ultrasonic transducer D, wherein the ultrasonic transducer A and the ultrasonic transducer C are connected with a transmitting/receiving conversion circuit, and the ultrasonic transducer B and the ultrasonic transducer D are connected with a signal receiving and processing circuit;
the ultrasonic transducer A and the ultrasonic transducer B are arranged on the main oil way, the mounting positions of the ultrasonic transducer A and the ultrasonic transducer B on the main oil way are positioned on the same horizontal plane, the ultrasonic transducer C and the ultrasonic transducer D are arranged on the oil return way, and the mounting positions of the ultrasonic transducer C and the ultrasonic transducer D on the oil return way are positioned on the same horizontal plane.
Has the advantages that:
the utility model relates to a practical measuring device which can accurately measure the fuel consumption of gasoline vehicles (including electric control fuel injection type vehicles) and diesel vehicles. The oil consumption measuring device has the advantages of high oil consumption measuring speed, high measuring precision, wide measuring range, strong anti-interference capability and the like. The test contents of timing test, hundred kilometers test, constant-speed oil consumption and accelerated oil consumption of the automobile oil consumption can be realized. Specifically, the method comprises the following steps:
(1) the performance of each component is matched, so that the system can work stably, and the characteristics of the test system can be exerted to the maximum extent.
(2) The design of each local circuit and the circuit board fully embodies the optimization of the overall performance of the system, and the used circuits and the wiring are few, thereby simplifying the circuit structure, saving the cost and simultaneously achieving the advantage of portability.
(3) The utility model has the advantage of low power consumption, and each part of the system is in a working state when in need and in a power-saving state when not in use.
(4) The automatic timing and the automatic reading of the oil consumption improve the detection precision.
Drawings
FIG. 1 is a schematic diagram of the appearance structure of the present invention;
FIG. 2 is a system schematic;
FIG. 3 is an AT89C55 pin configuration;
FIG. 4 is a circuit diagram of an ultrasonic transmitter module;
FIG. 5 is a circuit diagram of an acoustic signal receiving and amplifying circuit;
FIG. 6 is a fourth order bandpass filter circuit;
FIG. 7 is a MAX912 structure diagram;
FIG. 8 is an FM31256 interface circuit;
FIG. 9 is a pin diagram of HT1621B LCD controller;
FIG. 10 is a matrix keyboard matrix of 4 × 2 steps;
FIG. 11 is a circuit diagram of four independent keys;
FIG. 12 is a regulated power supply circuit;
FIG. 13 is a +5V power module;
FIG. 14 is a-5V power module;
FIG. 15 is a side view of FIG. 1;
fig. 16 is a flow chart of the working principle.
Detailed Description
The first embodiment is as follows:
an ultrasonic oil consumption meter of the present embodiment, as shown in an external schematic structure diagram of fig. 1 and a system schematic diagram of fig. 2, includes a housing 1, a main circuit chip 2, an analog circuit module 3, a printing module 4, a keyboard module 5, a display module 6, a data storage module 7, a data transmission module 8, a clock circuit 9, a clock 10, a storage grid 11, a power supply module 12, a set of ultrasonic transducers 13, and a set of clamping mechanisms for mounting the ultrasonic transducers 13;
a main circuit chip 2, an analog circuit module 3, a printing module 4, a storage grid 11, a power supply module 12, a clock circuit 9, a display module 6, a keyboard module 5 and a data storage module 7 are arranged in the shell 1;
the main circuit chip 2 is connected with the analog circuit module 3, the clock circuit 9, the display module 6, the keyboard module 5, the data storage module 7 and the data transmission module 8; the analog circuit module 3 is connected with a group of ultrasonic transducers 13, and the clock circuit 9 is connected with the clock 10;
wherein,
the analog circuit module 3 comprises a transmitting/receiving conversion circuit 14, a signal receiving and processing circuit 15 and an ultrasonic transmitting circuit 16, wherein the ultrasonic transmitting circuit 16 transmits signals to the transmitting/receiving conversion circuit 14, and the transmitting/receiving conversion circuit 14 transmits signals to the signal receiving and processing circuit 15; and, the signal receiving and processing circuit 15 includes an ultrasonic signal receiving and amplifying circuit, a filter circuit, and a sampling gating and zero-crossing comparison circuit. The system is designed to be divided into two blocks to reduce mutual interference of analog signals and digital signals. All modules are mutually matched under the control of the single chip microcomputer, and a hardware circuit structure of the system is formed together.
The group of ultrasonic transducers 13 comprises an ultrasonic transducer A, an ultrasonic transducer B, an ultrasonic transducer C and an ultrasonic transducer D, wherein the ultrasonic transducer A and the ultrasonic transducer C are connected with a transmitting/receiving conversion circuit 14, and the ultrasonic transducer B and the ultrasonic transducer D are connected with a signal receiving and processing circuit 15;
the ultrasonic transducer A and the ultrasonic transducer B are arranged on a main oil way, the mounting positions of the ultrasonic transducer A and the ultrasonic transducer B on the main oil way are positioned on the same horizontal plane, the ultrasonic transducer C and the ultrasonic transducer D are arranged on an oil return way, and the mounting positions of the ultrasonic transducer C and the ultrasonic transducer D on the oil return way are positioned on the same horizontal plane.
The second embodiment is as follows:
different from the first specific embodiment, in the ultrasonic fuel consumption meter of the present embodiment, the clock circuit 9 further includes a timing circuit 17, a timing output control circuit 18, a timer circuit 19, and a frequency divider circuit 20.
The third concrete implementation mode:
different from the first embodiment, in the ultrasonic fuel consumption meter of the present embodiment, when looking down on the ultrasonic fuel consumption meter, the main circuit chip 2 is located in the middle of the housing 1, the right side of the main circuit chip 2 is connected with and mounted with the analog circuit module 3, the left side of the main circuit chip 2 is mounted with the printer, and the lower side of the main circuit chip 2 is mounted with the storage grid 11 and the power supply module 12; the terms "upper side", "left side", "right side", "lower side" and the like are used for describing orientations only and are not intended to limit and protect technical limitations.
The fourth concrete implementation mode:
different from the first specific embodiment, in the ultrasonic fuel consumption meter of the present embodiment, the display module 6 further includes a liquid crystal display 21 and a liquid crystal display module chip 34, the liquid crystal display 21 and the liquid crystal display module chip 34 are fixed together, and the liquid crystal display 21 is embedded in the housing 1.
The fifth concrete implementation mode:
different from the first specific embodiment, in the ultrasonic oil consumption meter of the present embodiment, the main circuit chip 2 further includes a main control chip and an FPGA, the main control chip is matched with the FPGA, and the main control chip selects an AT89C55 single chip microcomputer; the FPGA generates a trigger signal for the ultrasonic transducer 13, and the FPGA completes data access and information human-computer interaction together with the keyboard module 5, the display module 6 and the data storage module 7.
The sixth specific implementation mode:
different from the first specific embodiment, the ultrasonic oil consumption meter of the present embodiment further includes an external power source interface 22, a main oil path sensor interface 23, an oil return path sensor interface 24, an RS-485 interface 25, and a power switch 26 on the housing 1,
the external power interface 22 is used for connecting the power module 12 with an external power supply;
the main oil path sensor interface 23 is used for connecting the ultrasonic transducer A and the ultrasonic transducer B to the analog circuit module 3;
the oil return sensor interface 24 is used for connecting the ultrasonic transducer C and the ultrasonic transducer D to the analog circuit module 3;
the RS-485 interface 25 is connected with the data transmission module 8.
The seventh embodiment:
different from the first embodiment, the ultrasonic fuel consumption meter of the embodiment,
A. the AT89C55 singlechip is used as a control core of the whole system, and mainly completes the functions of system time sequence control, generation of ultrasonic trigger signals, receiving and processing of measured data, keyboard control, display and the like, and the AT89C55 singlechip meets the requirements of applicability, purchasability and developability, so the AT89C55 singlechip of ATMEL company is selected in the design.
Main performance parameters of AT89C 55:
(1) is fully compatible with MCS-51 product instructions and pins;
(2) the Flash memory can be rewritten by 20k bytes;
(3)32 programmable I/O port lines;
(4)3 16 bit timing/counters;
(5)8 interrupt sources;
(6)25x8 bytes of internal RAM;
(7) low power idle and power down modes;
B. pin configuration of single chip microcomputer
The AT89C55 pin configuration is shown in FIG. 3:
(1) p0.1 receiving a counting end signal from the FPGA counter;
(2) p0.2, P0.3 and P0.4 are connected with the SCL end of the ferroelectric memory chip FM 31256;
(3) p0.5, P0.6, P0.7 are connected to CS, WR, DATA terminals of the LCD controller HT 1621B;
(4) the port P1 is an 8-bit parallel input port of the counting result of the FPGA counter;
(5) p2.0 is connected with a pull-up resistor for controlling the switching between the printer and the serial port;
(6) p2.1 outputs ultrasonic wave forward flow/backward flow propagation direction selection signals;
(7) p2.2 is connected with a main oil path downstream ultrasonic transducer 13 to trigger group pulse;
(8) p2.3 is connected with a main oil way counter-flow ultrasonic transducer 13 to trigger group pulse;
(9) p2.4, P2.5 and P3.2 are connected with the keyboard matrix;
(10) p2.6 is connected with an oil return circuit downstream ultrasonic transducer 13 to trigger group pulse;
(11) p2.7 is connected with an oil return path countercurrent ultrasonic transducer 13 to trigger a group pulse;
(12) p3.0 and P3.1 are connected with a printer and a 485 serial port.
The ultrasonic wave transmitting circuit 16:
the transmission and reception of ultrasonic waves are important components of an ultrasonic flowmeter system, and the ultrasonic triggering mode can be divided into single pulse triggering, pulse group triggering and continuous pulse triggering. The mode of burst triggering is selected according to the characteristics of the ultrasonic flowmeter system. And the mode of selecting the pulse group triggering, the number of pulses contained in each group of pulse groups is considered, the number of pulses is large, and the energy of the ultrasonic wave signal is increased due to superposition, so that the receiving of the transducer is facilitated. However, the larger the number of pulses, the larger the time interval required between two consecutive measurements, otherwise the received signal cannot be distinguished, and a general document suggests to use 4 to 8 pulses, but according to actual experiments and calculations, a burst triggering mode of 5 pulses per group is adopted.
The diameter of the main oil supply pipeline of the automobile engine is very small, so the system is designed into a pipeline ultrasonic flowmeter with a small diameter, the traditional mode of generating high-voltage pulse by using a high-power field effect transistor and a transformer is not adopted to excite the ultrasonic transducer 13, the ultrasonic transmitting circuit 16 selects a double-channel high-speed MOSFET (metal oxide semiconductor field effect transistor) driver TPS2811 to excite the transducer in a low-voltage mode, and the excitation voltage is 12V. The transducer is made to emit 200KHz ultrasonic waves for measurement. The pulse sent by the single chip microcomputer drives the transducer to send an ultrasonic signal through the 7407 chip (reverse buffer/driver) and the level conversion of the TPS 2811. The TPS2811 is capable of providing peak currents of up to 2A to high capacitance loads. As shown in fig. 4, R1 is a pull-up resistor. When a 12V high signal needs to be transmitted, the TP2811 switch S selects 12V, and then 7407 needs to convert the signal level to meet the requirement. The TPS2811 input is non-tri-stated and diode D1 is used to prevent signal leakage through the TPS2811 input after transmission is stopped.
Signal receiving and processing circuit 15:
the signal receiving and processing circuit 15 is used for amplifying, filtering and comparing ultrasonic signals received by the ultrasonic transducer A, the ultrasonic transducer B, the ultrasonic transducer C and the ultrasonic transducer D, the requirement of the signal processing circuit is high, and the zero-crossing comparison circuit generates a counting end signal to directly influence the precision of a final timing result;
the circuit diagram of the ultrasonic signal receiving and amplifying circuit is shown in fig. 5, two diodes Dl and D2 are silicon tubes 1N4148, and when the transducer is used for transmitting, the voltage of the input end of the integrated operational amplifier is clamped to be 0.7V at the maximum, so that the amplifying circuit is protected. The resistor plays a role in limiting current and needs larger rated power. The analog switch 4066 (four-way analog switch) is turned on at a specific time after the transmission of the transmitting terminal is completed, allowing the received signal to enter a subsequent amplification processing circuit, so as to avoid misjudgment of timing end caused by interference signals and realize secondary protection of the amplification circuit. 4066 the on-off is controlled by the switching value output by FPGA.
The ultrasonic signal receiving and amplifying circuit adopts a broadband double operational amplifier TLE2072, and the TLE2072 is a low-noise, high-performance, high-speed and internal compensation JFET input operational amplifier manufactured by using a complementary bipolar enhancement process of Texas instruments. The low-noise high-speed broadband low-noise high-speed broadband high-frequency broadband high-speed broadband high-frequency broadband high-speed broadband high-frequency broadband wireless communication system is combined with low-speed broadband high-frequency broadband high-speed broadband high-frequency high-speed broadband high-frequency broadband high-speed broadband high-frequency broadband high-frequency high-speed broadband high-frequency high-frequency-speed broadband high-frequency high-speed broadband high-frequency high-. The TLE2072 has two operational amplifiers to form a two-stage negative feedback amplifier circuit. The receiving transducer converts the received ultrasonic pulse into a relatively weak electric signal, and the signal reaches the requirement of the signal which can be processed by the circuit through the two-stage negative feedback amplifying circuit.
After the received ultrasonic signal passes through the pre-amplifying circuit, the signal and noise are simultaneously amplified, and the introduction of the high-quality-factor band-pass filter can retain the signal with the required frequency, weaken other noise parts and provide the signal with high signal-to-noise ratio for a subsequent circuit. The filter circuit adopts a MAXIM (maximum integrated) 275 chip to carry out band-pass filtering on signals;
the MAX275 is composed of two independent second-order sections, and each second-order section realizes a Butuerworth, Bessel and Chebysev type band-pass or low-pass filter through the adjustment of an external resistor; MAX275 exhibits low noise and excellent dynamic performance over a continuous time range compared to switched capacitor filters; since clock 10 is not needed, there is no clock 10 noise; MAX275 central frequency is up to 300KHz, precision is +/-0.9%, and typical value of THD in the whole working temperature range is-86 dB; the operating voltage of the MAX275 is +5V or +/-5V;
the central frequency of the band-pass filter is 200KHz, the gain Hosr of the band-pass filter is 1, the design Q value is 12, the band-pass width of the band-pass filter is 16.6KHz, and the central frequency FoAfter Q value and gain Hosr are determined, R1、R2、R3、R4This can be obtained from the following equation:
R4＝R2-5KΩ＝5KΩ
the value of RX/RY is determined by the connection mode of the pin FC, the pin FC is grounded, the value of RX/RY is 1/5, and R is taken324K Ω, the resistance is feasible, and the quality factor Q is derived and calculated to be 12; the value of the external resistor is 5K-4M;the operational amplifier can be driven without generating larger parasitic capacitance; the value of the peripheral resistance is R1＝24KΩ，R2＝10KΩ，R3＝24KΩ，R4The connections of the peripheral circuit are as shown in fig. 6, 5K Ω;
a fourth-order Butuerworth (butterworth low pass filter) band pass filter is formed by the cascade of two second order sections. Compared with a common filter consisting of an operational amplifier and an RC circuit, the MAX275 (four-order and eight-order continuous time active filter) is used, so that the problems of complex calculation, difficult parameter adjustment, interference of parasitic capacitance, difficult Q (quality factor) value and the like are solved.
The counting accuracy of the counter is a key factor of the measurement accuracy of the ultrasonic flowmeter, the accurate opening and closing of the counter is important, and the purpose of the sampling gating circuit part is to avoid the influence of noise and transducer tailing signals on the generation of a counting stop signal. Confirming correct reception of the ultrasonic signal through an amplitude level tracking circuit composed of an operational amplifier, thereby gating a zero-crossing comparison circuit to generate a counter stop signal;
the sampling gating circuit comprises an analog switch CD4066 (four-bidirectional analog switch), an operational amplifier TLE2072 and a comparator MAX 912;
the zero-crossing comparison circuit adopts a double-group high-speed low-power-consumption high-precision voltage comparator MAX912 produced by MAXIM company; the amplitude of the envelope of the received signal will also change due to the change in the flow rate of the fluid in the pipe, but since the change in amplitude is a continuous process, the peak value of the last received signal can be used to compare the amplitude of the ultrasonic signal received in this round with the amplitude of the previous received signal stored in the stored value capacitor, to generate the gating signal for the comparator in the zero-crossing comparison circuit.
The stretched pulse is used to gate a comparator MAX912-2 (high speed comparator) in the circuit, the comparator 2 outputs a pulse signal at this time, and the pulse lower edge triggers a counter to stop counting. The ideal 0V cannot be selected for eliminating the influence of noise on the threshold voltage of the comparator 2 (voltage value obtained from the intersection of the approximate straight line of the on-state characteristic and the voltage axis), and the tail signal is eliminated in the previous comparison and cannot influence the subsequent comparison circuit any more, so that the threshold voltage of the voltage comparison module in the signal receiving and processing circuit 15 is + 0.2V;
the comparator is selected from a double-group high-speed low-power-consumption high-precision voltage comparator MAX912 produced by MAXIM company. Within the MAX912 slice are two independent comparators as shown in fig. 7. The device has high propagation speed (the typical value is 10ns), low power consumption (the working current of a single comparator is 6mA), each comparator has an independent latch use function, and the working voltage is 5V or +/-5V; it differs from other high speed comparators in that the MAX912 remains stable when a slow moving signal is received.
The transmitting/receiving conversion circuit 14 is used for switching the two ultrasonic transducers 13 between transmitting and receiving, and the connection between the two ultrasonic transducer 13 circuits saves hardware resources, and the utility model selects the analog switch 4066;
the specific implementation mode is eight:
different from the specific embodiment, the ultrasonic oil consumption meter of the embodiment further comprises a data storage module 7, wherein the data storage module 7 is used for storing data such as accumulated flow data and the like, and ensuring that the data are not lost and important parameters required by flow calculation are also stored in the data storage module under the condition that the oil consumption meter is accidentally powered off, so that system calling is facilitated;
the data storage module 7 of the fuel consumption meter selects a ferroelectric memory chip FM31256 of RAMTRON company; the main functions of the ferroelectric memory chip FM31256 include ferroelectric nonvolatile memory, real-time clock, low voltage reset, watchdog counter, nonvolatile event counter, lockable serial data identification and a general comparator for power failure interrupt output; the highly integrated device can replace a plurality of elements, and the purposes of simplifying the design and improving the stability of the system are achieved. The operating power range is 2.7V-5V, the SOIC package is provided with 14 pins, and the static working current is as low as 150 muA; the non-volatile memory of FM31256, real-time clock 10, watchdog are selected to include several partial functions of power supply monitoring; the operation of the ferroelectric memory chip FM31256 is very simple, and the operation of the above functions can be realized by three lines of SCL, SDA, CAL/PF0, and the interface circuit is shown in fig. 8. The ferroelectric memory chip FM31256 adopts two-wire system IIC serial interface, its SCL, SDA connect I/O port P0.2, I/O port P0.3 of AT89C55 singlechip, imitate IIC time sequence to carry on the read-write operation to FM31256 through I/O port of AT89C55 singlechip, carry on the storage of the data, the high-speed high-efficient storage principle of the ferroelectric memory can guarantee the effective going on of the data storage; the real-time clock 10 of the ferroelectric memory chip FM31256 comprises a crystal oscillator, a frequency dividing circuit and a register, which divides a 32.768Hz time-base signal with a resolution of 1 HZS; the 2200 muF capacitor is used to provide temporary backup power for the real time clock;
the liquid crystal display screen 21 adopts a 12864LCD, and 12864 is the short lattice number of a 128 multiplied by 64 lattice liquid crystal module;
12864 basic parameters:
the module displays the effect: yellow-green bottom black words, blue bottom white words and white bottom black words;
the visual angle is 6 o 'clock and 12 o' clock;
working temperature: -20 ℃ -70 ℃;
storage temperature: -30 ℃ -80 ℃;
lattice format: 128x 64;
the connection mode is as follows: the 20 pins are connected with an LCD controller;
basic application: the dot matrix has relatively low screen display cost and is suitable for the display field of various instruments and small equipment;
in the system, a display module 6 adopts an HT1621 type double-row segment code type LCD controller produced by HOLTEK company; the HT1621 type double-row segment code LCD controller is a 128-point memory mapping and multifunctional LCD driver, the software configuration characteristic of the controller makes the controller suitable for various LCD application occasions including an LCD module and a display subsystem, and the operation control is simple, and the main characteristics are as follows:
(1) the operating voltage is 2.7V-5.2V;
(2) a 256KHz RC oscillator is built in, and an external 32.768KHz crystal oscillator or a 256KHz external clock 10 source can also be used;
(3) the POWER DOWN mode can be used for reducing POWER consumption;
(4) a 32 x4 bit display RAM is built in;
(5) a 3-wire serial interface;
(6) the read-write address is automatically increased;
an interface circuit between the HT1621 type double-row segment code type LCD controller and the AT89C55 single chip microcomputer is shown in FIG. 9, CS is a chip selection signal, and low level is effective. The WR terminal is externally connected with a pull-up resistor, and DATA is written into HT1621 on a DATA line when the input signal rises. DATA is a serial DATA input/output port.
The keyboard module 5 is a contact type structure and is a non-coding keyboard matrix; a matrix keyboard is adopted, which is suitable for a more complex system or function control with more keys, and is a matrix keyboard with 4 × 2 orders as shown in fig. 10;
the 4 x 2-step matrix keyboard is formed by crossing 4 row lines and 2 column lines
Eight key positions of "start", "end", "print", "send"; the keys are positioned at the intersection of the rows and the columns, so that 8 keys are formed; the row line and the column line at the intersection are not connected, and when the key is pressed down, the row line and the column line at the intersection are conducted; the row line in fig. 10 is tied to VCC through a pull-up resistor. When no key is pressed, the row line is in a high level state; when a key is pressed down, the row line and the column line are conducted at the intersection point, and the level of the row line is determined by the level of the column line connected with the row line at the moment to identify whether the key is pressed down; however, each row line in the matrix keyboard is intersected with 2 column lines, and whether the key at the intersection is pressed or not affects the level of the row line and the column line of the key, and the keys affect each other, so that the signals of the row line and the column line must be matched for proper processing during key analysis to determine the position of a closed key.
This can be achieved
Eight key positions of "start", "end", "print", and "send". The using method comprises the following steps: when pressed down
Moving a cursor when pressing a key, and selecting a test item to be performed; press the "start" key and test. After the test value is reached, the test is finished, an end key is pressed, the test is finished, and the next test can be carried out; pressing the 'print' key to print the test result, and when pressing the 'send' key, sending the test result out through the RS485 port;
the output of the keyboard matrix is provided with a four-input AND gate chip 74HC 21; when one of the four inputs is low, the output is low. The output end of the 74HC21 is connected to the external interrupt 0 of the P3.2 pin of the singlechip, so that under the condition of higher real-time requirement, P2.5 and P2.6 are set as full-low waiting key triggering, and when any key is pressed down, the system can enter an interrupt service program, thereby improving the response time of the keyboard and being very practical under the condition of higher real-time requirement of the system. This connection method is adopted.
The data transmission module 8 selects a control chip MAX485 of an RS-485 serial port;
the MAX485 interface chip is an RS-485 chip from Maxim corporation. The power supply works by +5V, the rated current is 300 muA, and a half-duplex communication mode is adopted for converting the TTL level into the RS-485 level; the MAX485 core internally comprises a driver and a receiver, and RO and DI ends are respectively the output of the receiver and the input end of the driver and are respectively connected with RXD and TXD of the singlechip; the/RE end and the DE end are respectively an enabling end for receiving and sending, and when the/RE end is logic 0, the device is in a receiving state; when DE is logic 1, the device is in a sending state, and because MAX485 works in a half-duplex state, only one pin of the singlechip is needed to control the two pins; the A end and the B end are differential signal ends for receiving and sending respectively, and when the level of the pin A is higher than that of the pin B, the data sent is represented as 1; when the electricity of AWhen the value is lower than the end B, the data sent is represented as 0; the wiring is very simple when the single chip microcomputer is connected. Only one signal is needed to control the receiving and the sending of MAX485, and DE,
The receiving enabling end of the control chip of the printer is connected with the port P0.0 of the single chip microcomputer, so that the data transmission module 8 is connected with the single chip microcomputer; the single chip microcomputer is enabled to multiplex the control of the printer and the 485 interface.
The specific implementation method nine:
different from the first specific embodiment, the power supply module 12 of the ultrasonic fuel consumption meter of the first embodiment comprises a storage battery 30, a 12V power supply system, an LM2576-5, a polarity-variable DC-DC converter ICL7660 and another model LM2576-3.3 of the LM 2576;
the power supply is the energy core of the detection instrument. The stable power supply is the basis for stable operation of the detection instrument system. Because the automobile storage battery is supplied with power by 12V, a 12V power supply system is also selected for the utility model and is used for charging on the vehicle or utilizing a vehicle-mounted power supply to continue working when the system storage battery is not charged; since the working voltage of the single chip microcomputer is 5V, a 12V power supply is converted into direct current +5V through one LM2576-5 after being subjected to large and small capacitance filtering; because the-5V analog power supply does not need too large output power, a commonly used polarity-variable DC-DC converter ICL7660 is adopted to convert the +5V power supply to generate the power supply; the 3.3V power supply required by the system is obtained from another model LM2576-3.3 of LM 2576.
The power module 12 is shown in fig. 12, fig. 13 shows a +5V power module, and fig. 14 shows a-5V power module.
The detailed implementation mode is ten:
different from the first specific embodiment, in the ultrasonic fuel consumption meter of the present embodiment, the ultrasonic transducer 13 is configured to convert an electrical signal into mechanical vibration or convert the mechanical vibration into an electrical signal;
the TK200 ultrasonic sensor is selected as the ultrasonic transducer 13, the center frequency of the TK200 ultrasonic sensor is 200kHz, the PVDF is packaged on the end face of the TK200 ultrasonic sensor, chemical erosion can be resisted, and the TK and the PVDF are in a transmitting and receiving bidirectional mode, so that the cost can be reduced, and measurement errors caused by non-uniform parameters of the ultrasonic transducer 13 are avoided to a certain extent. The diameter size is 6 mm.
The concrete implementation mode eleven:
different from the first specific embodiment, in the ultrasonic oil consumption meter of the present embodiment, the printing module is connected to a printer 27, the printer 27 is fixed in the housing 1 through a printer bolt 28, the printer 27 is provided with a printer power supply 29, and the printer 27 is an embedded micro printer of the WH-a9 model manufactured by beijing bright company;
in order to keep the data displayed by the display and facilitate the research on the test data anytime and anywhere, and because of the portable design, a miniature printer needs to be installed in the fuel consumption instrument system. Because the number of pins of the main singlechip is limited, a panel type serial port micro printer which is convenient to install is selected;
the main characteristics and parameters are as follows:
(1) low noise direct thermal printing;
(2) the printing speed is 50 mm/s (when the character rate is 25%);
(3) high speed and low power consumption are freely selected;
(4) the system supports a 3.3V low-voltage system and supports a 3.5V-9V power supply;
(5) both RS-485 serial ports and parallel ports are available;
(6) rich graphics/curves/text printing functions;
(7) easy packaging paper;
(8) a printing mode: direct thermal line printing;
(9) paper width: 57 mm;
(10) printing width: 48 mm;
(11) resolution ratio: 8dots/mm (384 dots/line);
(12) printhead life: 6,000,000 character lines;
(13) external dimensions (W × H × Dmm): 95mm × 91mm × 59 mm;
(14) mounting size (W × Hmm): 66mm × 41 mm;
(15) embedding depth: 54 mm;
the storage battery 30 is fixed on the inner wall of the shell 1 through a battery clamping device 31, and the battery clamping device 31 is fixed on the inner wall of the shell 1 through a group of battery positioning screws 32;
the keyboard module 5 is connected with a group of keys 33;
the LCD module chip 34 is selected from HT1621 type double-row segment code LCD controller manufactured by HOLTEK.
The working principle is as follows:
as shown in fig. 16, after reading the preset measurement parameters and history information in the data memory, the AT89C55 single chip outputs trigger burst pulses to the downstream ultrasonic transducer a and the downstream ultrasonic transducer C, and simultaneously notifies the high-speed counting module in the FPGA to start counting. The trigger signal excites the ultrasonic transducer A to generate ultrasonic wave through the drive circuit, and after the ultrasonic transducer B and the ultrasonic transducer D receive the ultrasonic wave signal, the weak signal is sent to a signal receiving and preprocessing module which consists of a preamplification circuit, a band-pass filter circuit, a peak detection circuit, a zero-crossing comparison circuit, a pulse broadening circuit and the like to be processed. After the ultrasonic signal is confirmed to be successfully received, a high-speed counter of the FPGA is timely informed to stop counting, the downstream propagation time of the ultrasonic wave represented by the count value in the pipeline is temporarily stored in a register of the FPGA, the AT89C55 single chip microcomputer is informed to start to transmit next time, and after a plurality of downstream measurements are completed according to the needs of the system, the average value t of the downstream propagation time is storedAAnd tCAnd informs the AT89C55 of the singlechip. The average value of multiple measurements is used as the ultrasonic transit time, so that the error can be reduced, and the measurement precision can be improved. The AT89C55 single chip microcomputer outputs trigger group pulse to the reverse flow ultrasonic transducer B, the analog switch is controlled by the timer module of the FPGA to realize the switching of the transmitting/receiving conversion circuit 14, and the previous process is repeated to obtain the average value t of the reverse flow propagation timeBAnd tD. The AT89C55 singlechip reads the data and then obtains the flow velocity and the flow rate of the fluid through calculation, and sends the result to the liquid crystal display screen for display. And in the conventional process, the display interface can be switched by key interruption.
The introduction of the FPGA not only simplifies the design of system hardware, but also improves the stability, reliability and upgradability of the system.
The electronic chips are all existing products which are commercially available, are not the protection object of the utility model, and the connection relationship among the modules or chips is clearly recorded.
Claims (10)
1. An ultrasonic oil consumption meter is characterized in that: the device comprises a shell, a main circuit chip, an analog circuit module, a printing module, a keyboard module, a display module, a data storage module, a data transmission module, a clock circuit, a clock, a storage grid, a stabilized voltage power supply, a group of ultrasonic transducers and a group of clamping mechanisms for mounting the ultrasonic transducers;
a main circuit chip, an analog circuit module, a printing module, a storage grid, a voltage-stabilized power supply, a clock circuit, a display module, a keyboard module and a data storage module are arranged in the shell;
the main circuit chip is connected with the analog circuit module, the clock circuit, the display module, the keyboard module, the data storage module and the data transmission module; the analog circuit module is connected with a group of ultrasonic transducers, and the clock circuit is connected with a clock;
wherein,
the analog circuit module comprises a transmitting/receiving conversion circuit, a signal receiving and processing circuit and an ultrasonic transmitting circuit, wherein the ultrasonic transmitting circuit transmits signals to the transmitting/receiving conversion circuit, and the transmitting/receiving conversion circuit transmits the signals to the signal receiving and processing circuit; the signal receiving and processing circuit comprises an ultrasonic signal receiving and amplifying circuit, a filter circuit, a sampling gating circuit and a zero-crossing comparison circuit;
the group of ultrasonic transducers comprises an ultrasonic transducer A, an ultrasonic transducer B, an ultrasonic transducer C and an ultrasonic transducer D, wherein the ultrasonic transducer A and the ultrasonic transducer C are connected with a transmitting/receiving conversion circuit, and the ultrasonic transducer B and the ultrasonic transducer D are connected with a signal receiving and processing circuit;
the ultrasonic transducer A and the ultrasonic transducer B are arranged on the main oil way, the mounting positions of the ultrasonic transducer A and the ultrasonic transducer B on the main oil way are positioned on the same horizontal plane, the ultrasonic transducer C and the ultrasonic transducer D are arranged on the oil return way, and the mounting positions of the ultrasonic transducer C and the ultrasonic transducer D on the oil return way are positioned on the same horizontal plane.
2. The ultrasonic oil consumption meter according to claim 1, wherein: the clock circuit also comprises a timing circuit, a timing output control circuit, a timer circuit and a frequency divider circuit.
3. An ultrasonic oil consumption meter according to claim 1 or 2, characterized in that: the main circuit chip is positioned in the middle of the shell, the right side of the main circuit chip is connected with and provided with the analog circuit module, the left side of the main circuit chip is provided with the printing module, and the lower side of the main circuit chip is provided with the storage grid and the stabilized voltage supply.
4. An ultrasonic oil consumption meter according to claim 3, characterized in that: the display module also comprises a liquid crystal display screen and a liquid crystal display module chip, the liquid crystal display screen and the liquid crystal display module chip are fixed into a whole, and the liquid crystal display screen is embedded on the shell.
5. An ultrasonic fuel consumption meter according to claim 1, 2 or 4, wherein: the main circuit chip also comprises a main control chip and an FPGA, wherein the main control chip selects an AT89C55 singlechip.
6. The ultrasonic oil consumption meter according to claim 5, wherein: the shell is also provided with an external power supply interface, a main oil circuit sensor interface, an oil return circuit sensor interface and an RS-485 interface,
the external power supply interface is used for connecting a stabilized voltage power supply and an external power supply;
the main oil path sensor interface is used for connecting the ultrasonic transducer A and the ultrasonic transducer B to the analog circuit module;
the oil return sensor interface is used for connecting the ultrasonic transducer C and the ultrasonic transducer D to the analog circuit module;
the RS-485 interface is connected with the data transmission module.
7. An ultrasonic fuel consumption meter according to claim 1, 2, 4 or 6, characterized in that:
the ultrasonic transmitting circuit adopts a double-channel high-speed MOSFET driver TPS2811, the transducer is excited in a low-voltage mode, and the excitation voltage is 12V;
the signal receiving and processing circuit is used for amplifying, filtering and comparing ultrasonic signals received by the ultrasonic transducer A, the ultrasonic transducer B, the ultrasonic transducer C and the ultrasonic transducer D, and comprises an ultrasonic signal receiving and amplifying circuit, a filtering circuit, a sampling gating circuit and a zero-crossing comparison circuit;
wherein,
the ultrasonic signal receiving and amplifying circuit adopts a broadband double operational amplifier TLE 2072;
the filter circuit adopts MAX275 chip of MAXIM company to carry out band-pass filtering on the signal;
the sampling gating circuit comprises an analog switch CD4066, an operational amplifier TLE2072 and a comparator MAX 912;
the zero-crossing comparison circuit selects a voltage comparator MAX 912;
the transmitting/receiving conversion circuit is used for switching the two ultrasonic transducers between transmitting and receiving, and the connection between the two ultrasonic transducer circuits saves hardware resources, and an analog switch 4066 is selected.
8. The ultrasonic oil consumption meter according to claim 4, wherein: the fuel consumption meter also comprises a data storage module used for storing accumulated flow data;
the data storage module of the fuel consumption meter selects a ferroelectric memory chip FM31256 of RAMTRON company; the main functions of the ferroelectric memory chip FM31256 include ferroelectric nonvolatile memory, real-time clock, low voltage reset, watchdog counter, nonvolatile event counter, lockable serial data identification and a general comparator for power failure interrupt output; the operating power range is 2.7V-5V, the SOIC package is provided with 14 pins, and the static working current is low; the FM31256 of the ferroelectric memory chip adopts two-wire system IIC serial interface, its SCL, SDA connect I/O port P0.2, I/O port P0.3 of AT89C55 one-chip computer, imitate IIC time sequence to carry on the read-write operation to FM31256 through I/O port of AT89C55 one-chip computer, carry on the storage of the data; the real-time clock of the ferroelectric memory chip FM31256 includes crystal oscillator, frequency dividing circuit and register, it divides the frequency of 32.768Hz time base signal, the resolution is;
the liquid crystal display screen is a 12864 LCD;
the liquid crystal display module chip adopts an HT1621 type double-row segment code type LCD controller;
the display module adopts an HT1621 type double-row segment code type LCD controller;
the output of the keyboard module is provided with a four-input AND gate chip 74HC 21;
the printing module is connected with a printer, and the printer is an embedded micro printer;
the data transmission module adopts a control chip MAX485 of an RS-485 serial port.
9. An ultrasonic fuel consumption meter according to claim 1, 2, 4, 6 or 8, characterized in that: the ultrasonic oil consumption meter further comprises a power supply module, wherein the power supply module comprises a storage battery, a 12V power supply system, an LM2576-5, a polarity-variable DC-DC converter ICL7660 and an LM 2576-3.3;
the 12V power supply system is used for charging on a vehicle or continuously working by utilizing a vehicle-mounted power supply when a system storage battery is in no power;
after a 12V power supply is subjected to large and small capacitance filtering, the power supply is converted into direct current +5V through an LM 2576-5;
a polarity-variable DC-DC converter ICL7660 is used for converting a +5V power supply to generate;
the 3.3V power supply required by the system is obtained by LM 2576-3.3.
10. The ultrasonic oil consumption meter according to claim 9, wherein: the ultrasonic transducer is used for converting an electric signal into mechanical vibration or converting the mechanical vibration into the electric signal;
the ultrasonic transducer adopts a TK200 ultrasonic sensor, the center frequency of the TK200 ultrasonic sensor is 200kHz, and the end face of the TK is packaged by PVDF.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120714798.1U CN216770704U (en) | 2021-04-08 | 2021-04-08 | Ultrasonic oil consumption instrument |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120714798.1U CN216770704U (en) | 2021-04-08 | 2021-04-08 | Ultrasonic oil consumption instrument |
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| CN216770704U true CN216770704U (en) | 2022-06-17 |
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| CN202120714798.1U Expired - Fee Related CN216770704U (en) | 2021-04-08 | 2021-04-08 | Ultrasonic oil consumption instrument |
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