Our car costs us a pretty penny. No matter how grateful we are to him for his work, from time to time we still want to reduce expenses on it and more carefully control the consumption of fuel, oils and technical fluids. In order to monitor these processes, it is necessary to know exactly what fuel consumption is for a given period of time. It is natural that this task cannot be done manually and by eye - for quick and accurate measurements you need a modern device that will do everything necessary work and will not take up much of your time. The Innotech company invites all car enthusiasts to purchase a fuel flow meter in order to always be aware of the costs of gasoline or diesel.
Fuel flow meter
A fuel flow meter is a device designed specifically for measuring fuel in automotive and other systems. This device has a wide range of applications - it is widely used not only for vehicles, but also for watercraft, diesel generators and other units and equipment where the source of energy is fuel. Most of these devices are distinguished by impeccable accuracy, as they are mounted directly into the fuel line. This means that the readings that flow meters will give diesel fuel, will be deprived of even minimal error.
This type of flowmeter is a convenient and practical device for all types of equipment using liquid fuel. So, it’s worth starting with the fact that a fuel flow meter for a car is easy to install - you won’t need much time for this, and the flow meter can start working immediately after installation.
Advantages of a fuel flow meter
The idea of buying a fuel flow meter will seem even more profitable to you if you learn about the advantages of this device. Despite its compactness and affordable price, the number of its valuable characteristics is truly impressive!
- High accuracy - as we said, this device is distinguished by the absence of errors in readings, which makes it one hundred percent effective in the field of assigned tasks;
- Reliable and strong housing, which is important for a device operating inside another system. It is not afraid of accidental damage and can withstand high-intensity loads;
- The device is highly resistant to wear and can work long years- of course, provided that you used it correctly and followed all operating rules.
The fuel flow meter can work with different types liquids. In addition to diesel fuel, it is also mineral oil, heating oil, as well as other varieties liquid fuel with a certain density and viscosity. In order not to make a mistake when choosing a device based on this parameter, carefully read its description technical parameters on the package.
The Innotech company is waiting for you to help you choose a fuel flow meter for your vehicle or equipment. You can find different prices for fuel flow meters with us - suitable for any budget and needs. With us you will not have problems with measuring fuel!
Designs for monitoring vehicle operating parameters have advanced significantly over last years. They have become more functional, more technologically advanced and simply closer to to the mass consumer. Accounting systems fuel consumption for now they occupy a peripheral place in the general niche of transport electrical engineering, but this area is of interest to everyone large quantity car enthusiasts. Against this background, it is quite logical that fuel flow meters appear, operating on different principles. It is also practiced self-production similar ones which, of course, have their own specifics.
General information and characteristics of flow meters
Most of these devices are traditional small-sized meters, the design of which is designed for installation in the fuel system. The dimensions of a typical device can be represented as follows: 50 x 50 x 100 mm.
This is a small block with throughput 100-500 l/h. The average error is 5-10%. During the flow of liquid, the device records in one way or another the indicators of the sensitive element and stores the received data. The implementation of the system of accounting, control and presentation of information may be different. For example, a flow-through fuel flow meter for a car is made with the expectation of manual readings. It may have a mechanical panel with data display or link to a liquid crystal display digital display in the cabin, but the information is not processed by the on-board computer. More technologically advanced devices also allow for the possibility of electronic accounting automatic mode. Depending on the flow dynamics, for example, on-board equipment can adjust certain parameters of the machine components and assemblies.
Types of devices
The classification is based precisely on the principle of taking into account readings, which is determined by the sensitive element. Today, the following flow meters for cars are distinguished:
- Coriolis. The operating principle is based on the Coriolis effect, in which the dynamics of the phases of mechanical vibrations in the tubes through which the fuel circulates is measured.
- Turbine. A blade device is integrated into the system, the rotation of the blades of which is converted into speed indicators. Thus, taking into account the parameters of the serviced channels, the volume of consumption is determined.
- Geared. Another type of mechanical fuel flow meter that records data through rotating elements. IN in this case compact is used gear, the movement of which allows you to record flow data.
- Ultrasonic. These are counters of a new type that do not contact the target environment at all, but record the parameters of changes in characteristics fuel system based on acoustic waves.
Features of diesel meters
Heavy fuel is usually used by trucks and special equipment, which place higher demands on fuel metering devices. The operating principle is usually mechanical. Moreover, the design of the sensors has more high degree insulation - for example, with Thus, the device is protected from the effects of an aggressive environment. The housing can be formed by an aluminum solid alloy, the measuring chambers of which are also provided with anti-friction coatings. The flow meter is located both in the fuel mixture supply line and in the return channel through which the liquid returns to the tank. Only if both circuits are covered can accurate data on consumption volume be obtained.
Additional functionality
The presence of a GPS monitoring system is perhaps the most modern addition to fuel consumption sensors. Such devices allow you to transmit information on-board computer over a wireless channel. Multifunction devices can comprehensively record flow data in several systems simultaneously. The main one can be taken into account fuel mixture and with additives and modifiers. The benefit of comprehensive monitoring is the ability to accurately control additives for fuel, transmission and other systems. In addition, it may be provided different modes operation of devices. There are fuel flow meters that, in addition to the counter function, perform control tasks idle move, record possible temperature overloads and, based on the information received, regulate climatic equipment. When introducing the device into the signaling infrastructure, the flow sensor may well be programmed to perform the tasks of monitoring the heater and the engine auto-start system.
Installation of flow meters
The devices are installed in the target metering loop through a physical insertion into the channel. And here it is important to emphasize that, depending on the car model, the fuel channels may initially have remote pipes with plugs, which can be used precisely as integration points for metering devices. It should also be taken into account that installation is carried out behind the filtration system. This solution will prevent possible contamination of the fuel flow meter and its premature exit out of service.
Mechanical fixation of massive devices is usually carried out on a complete frame, which is attached to the surface of the body. According to reviews from car enthusiasts, it is important to calculate so that the sensitive channel is sufficiently interfaced with the target environment, and the base of the housing can be securely fixed to the mounting platform with hardware. It is advisable that the installation location does not involve strong vibration loads and thermal influences.
Self-production of flow meters
According to drivers, it is quite difficult to assemble a full-fledged meter completely from scratch, and for this you need to have certain knowledge in radio engineering. However, based on a ready-made control unit such as a controller and sensor with an electric valve, the task is simplified. The sensor itself is integrated into the fuel line. It should be placed between the fuel pump and carburetor. As for the control unit, it is connected to the detector and output to the cabin. Using the CAN interface, you can connect your own fuel flow meter to the on-board electronics. As additional elements Mounting and controlling the sensor may require the use of fittings, washers, trays and bushings. The technical infrastructure must be designed to respond autonomously when the fuel pump opens.
How to fool the fuel flow meter?
Standard meters for monitoring gasoline or diesel consumption can be adjusted in one direction or another. The simplest way involves draining through the return line. It is enough to insert a fitting into this channel and drain the liquid through a hidden circuit. In some configurations, the built-in line may be used for a direct supply function, in which case the fuel flow meter meters simply will not provide up-to-date information. Another option provides thermal effect to the sensor. This applies specifically to liquid level detectors, which, after a thermal burn, stop working correctly, although outwardly they look intact. You can pour boiling water over the device or bring a heater to it for 5-10 minutes. But before doing this, it is worth thinking about the feasibility of such experiments.
FUEL FLOW METER FOR CAR
The repetition and adjustment of this flow meter is associated with certain difficulties, since many of its parts require high precision processing. Its electronic unit needs good noise immunity due to high level interference in on-board network car. Another disadvantage of this device is the increase in measurement error with decreasing fuel flow rate (and in idle mode and low engine load).
The device described below is free from the listed disadvantages and has more simple design sensor and electronic unit circuit. It does not have a device for monitoring the rate of fuel consumption; its function is performed by a total consumption meter. The frequency of operation is proportional to the rate of fuel consumption and is perceived by the driver by ear. This does not distract from driving, which is especially important in city traffic.
The flow meter consists of two components: a sensor with an electrovalve built into the fuel line between the fuel pump and carburetor, and an electronic unit located in the vehicle interior. The design of the sensor is shown in Fig. 1. Between the body 8 and the tray 2, an elastic diaphragm 4 is clamped, dividing the internal volume into upper and lower cavities. The rod 5 moves freely in the guide sleeve 7 made of fluoroplastic. The diaphragm is clamped at the bottom of the rod with two washers 3 and a nut. A permanent magnet 9 is installed at the upper end of the rod. In the upper part of the body, parallel to the channel in which the rod is located, two additional channels. They are equipped with two reed switches 10. In the lower position of the magnet, and therefore of the diaphragm, one reed switch is triggered, and in the upper position, another.
Puc.1 
. 1-Fitting, 2-Pan, 3-Washers, 4-Diaphragm, 5-Stem,
6 - Spring, 7 - Bushing, 8 - Housing, 9 - Magnet, 10 - Reed switches
The diaphragm moves to the upper position under the influence of fuel pressure coming from the fuel pump, and spring 6 returns it to the lower position. To connect the sensor to the fuel line, three fittings 1 are provided (one on the pan and two on the body).
Hydraulic circuit flowmeter is shown in Fig. 2. Through channel 3 and the solenoid valve, fuel from the fuel pump enters channels 1, 2 and fills the upper and lower cavities of the sensor, and through channel 4 enters the carburetor. The valve is switched under the influence of signals from an electronic unit (not shown in this diagram), controlled by a reed switch of the sensor.
Puc.2 
In the initial state, the solenoid valve winding is de-energized, channel 3 communicates with channel 1, and channel 2 is closed. The diaphragm is in the lower position, as shown in the diagram. The gasoline pump creates excess fluid pressure in the lower cavity 6. As the engine produces fuel from the upper cavity and the sensor, the diaphragm will slowly rise, compressing the spring.
When the top position is reached, reed switch 1 will operate and the electrovalve will close channel 3 and open channel 2 (channel 1 is constantly open). Under the action of a compressed spring, the diaphragm will quickly move down to its original position and pass fuel through channels 1, 2 from cavity b to a. Then the flow meter operation cycle is repeated.
The electronic unit (Puc.3) is connected to the sensor and solenoid valve with a flexible cable through the XT1 connector. Gorkoms SF1 and SF2 (1 and 2, respectively, according to Fig. 2) are installed in the sensor (in the diagram they are shown in a position where the magnet does not act on any of them); Y1 - valve solenoid winding. In the initial position, transistor VT1 is closed, contacts K1.2 of relay K1 are open and winding Y1 is de-energized. The sensor magnet is located next to the SF2 reed switch, so the reed switch does not conduct current.
Puc.3 
As fuel is consumed from sensor cavity a, the magnet slowly moves from reed switch SF2 to reed switch SF1. At some point the SF2 reed switch will switch, but this will not cause any change in the block. At the end of the stroke, the magnet will switch the reed switch SF1 and the base current of the transistor VT1 will flow through it and resistor R2. The transistor will open, relay K1 will operate and contacts K1.2 will turn on the valve solenoid, and contacts K1.1 will close the power supply circuit of the pulse counter E1.
As a result, the diaphragm together with the magnet will begin to quickly move down. At some point the reed switch SF1 after reverse switching will break the base current circuit of the transistor, but it will remain open, since the base current now flows through the closed contacts K1.1, diode VD2 and reed switch SF2. Therefore, the rod with the diaphragm and magnet will continue to move. At the end reverse the magnet will switch the reed switch SF2, the transistor will close, the valve electromagnet Y1 and the counter E1 will turn off. The system will return to its original state and a new cycle of its operation will begin.
Thus, counter E1 records the number of sensor activation cycles. Each cycle corresponds to a certain volume of fuel consumed, which is equal to the volume of space limited by the diaphragm in the upper and lower positions. The total fuel consumption is determined by multiplying the meter readings by the amount of fuel consumed in one cycle. This volume is set when calibrating the sensor. For the convenience of measuring fuel consumption, the volume per cycle is chosen to be 0.01 liters. If desired, this volume can be slightly reduced or increased. To do this, it is necessary to change the distance between the reed switches in height. With the specified sensor dimensions, the optimal aperture stroke is approximately 10 mm. The duration of the sensor cycle depends on the engine operating mode and ranges from 6 to 30 s.
When calibrating the sensor, it is necessary to disconnect the pipeline from the car's gas tank and insert it into a measuring vessel with fuel, and then start the engine and produce a certain amount of fuel. Dividing this amount by the number of cycles on the counter, the value of the unit volume of fuel per cycle is obtained.
The flow meter has the ability to turn it off using toggle switch SA1. In this case, the sensor diaphragm is constantly in the lower position and fuel through channels 2 and 3 through cavity a will directly flow into the carburetor. To realize the possibility of turning off the device in the solenoid valve, it is necessary to remove the rubber cuff covering channel 3, but this will worsen the error of the flow meter.
The electronic unit is mounted on printed circuit board made of fiberglass 1.5 mm thick. The board drawing is shown in Fig. 4. The parts installed on the board are outlined in the diagram with a dot-dotted line. The board is mounted in metal box and is mounted in the car interior under the instrument panel.
Figure 4 
The device uses a RES9 relay, passport PC4.529.029.11; solenoid valve - P-RE 3/2.5-1112. Counter SI-206 or SB-1M. Permanent magnet You can use any one with an end arrangement of poles and a length of 18...20 mm, it is only necessary that it moves freely in its channel without touching the walls. For example, a magnet from a remote switch RPS32 will do; you just need to grind it down to required sizes.
The sensor body and tray are machined from any non-magnetic petrol-resistant material. The wall thickness between the channels of the reed switches and the magnet should not be more than 1 mm, the diameter of the hole for the magnet is 5.1+0.1 mm, the depth is 45 mm. The rod is made of brass or steel 45, diameter - 5 mm, length of the threaded part - 8 mm, total length- 48 mm. The thread on the sensor fittings is M8, the hole diameter is 5 mm, and on the solenoid valve fittings there is a conical thread K 1/8" GOST 6111-52. The spring is wound from steel wire with a diameter of 0.8 mm GOST 9389-75. The diameter of the spring is 15 mm, pitch - 5 mm, length - 70 mm, force full compression- 300...500 g.
If the rod is made of steel, then the magnet is held on it due to magnetic forces. If the rod is made of non-magnetic metal, then the magnet must be glued or strengthened in any other way. To ensure that the operation of the sensor is not interfered with by the pressure of air compressed above the magnet, a bypass channel with a cross-section of about 2 mm2 should be provided in the bushing.
The diaphragm is made of polyethylene film 0.2 mm thick. It must be molded before installation into the sensor. To do this, you can use the sensor pan assembled with a fitting. It is necessary to make a technological clamping ring from sheet duralumin 5 mm thick. The shape of this ring exactly matches the assembly flange of the pallet.
To form the diaphragm, the rod assembly with its blank is inserted with inside into the hole of the pallet fitting and clamp the workpiece with a technological ring. Then the assembly is evenly heated from the diaphragm side, holding it above the burner flame at a distance of 60...70 cm and, slightly lifting the rod, the diaphragm is formed. In order for the diaphragm not to lose elasticity during operation, it is necessary that it is constantly in the fuel. Therefore, when long-term parking car, it is necessary to clamp the hose from the sensor to the carburetor to prevent evaporation of gasoline from the system.
The sensor and solenoid valve are installed on a bracket in engine compartment near the carburetor and fuel pump and a cable is connected to electronic unit.
The performance of the flow meter can be checked without installing it on the car using a pump with a pressure gauge connected instead of a fuel pump. The pressure at which the sensor is triggered should be 0.1 ... 0.15 kg/cm2. Tests of the flow meter on Moskvich and Zhiguli cars have shown that the accuracy of measuring fuel consumption does not depend on the engine operating mode and is determined by the error in setting a unit volume during calibration, which can easily be adjusted to 1.5...2%.
V. GUMENYUK Kharkov
December 24, 2011 at 03:23 pmHomemade flow meter for auto
- Development for Arduino
Hello! I'll tell you about my attempt to make an onboard flow meter based on Arduino Nano. This is my second product from Arduino, the first was a walking spider. After experimenting with light bulbs and servos, I wanted to do something more useful.
Of course, you could buy a finished product, maybe even for lower price(although I couldn’t find it for less). But it wasn't fun, and it might not have the features I wanted. In addition, a hobby, like sports, rarely justifies the costs in material form.
Before I talk about the process, I’ll show you a picture of what it looks like now. The program is still in the debugging stage, so the controller hangs on wires in the cabin, and the display is stuck on double-sided tape) In the future, this will be installed humanly.
The device calculates and displays kilometer fuel consumption on the display: instantaneous on the bottom line, average over the last kilometer on the top line.
The idea of making this thing came to me a long time ago, but it was hampered by the lack of information about what and how it works in my car. I have it quite old - Corolla E11 with a 4A-FE engine. I knew about the engine that it is fuel-injected and that the injectors have more or less constant performance, which is what its own control unit counts on. Therefore, the main idea of measuring flow is to measure the total duration of opening of the nozzles.
ECU, as suggested good man and as the instructions later confirmed, it controls the injector in the following way: plus is always supplied to it, and minus opens and closes depending on the wishes of the ECU. Therefore, if you connect to the negative wire of the injector, you can track the moment of its opening by measuring the potential: when the ECU shorts the injector to ground, 14 volts drop to zero. This simple thought did not immediately occur to me, because my knowledge of electronics is limited to a school physics course and Ohm’s law. Next, we needed to turn +14V into +5V, which can be supplied to the logic input of the controller. Here I somehow came up with a shunt circuit known to all electronics engineers, but before that I had to study the manuals and make sure that the injector resistance was negligibly small, and the logic input resistance was almost infinite.
To calculate the kilometer consumption, it was necessary to obtain data from the speed sensor. Everything turned out to be simpler with it, because it produces steps 0... +5V, the more steps, the more mileage. These steps went directly to the logical input without transformations.
I really wanted to display data on the LCD display. I was considering different variants and settled on a MELT text display for 234 rubles based on the Hitachi HD44780 microcontroller, which Arduino has been able to work with since birth.
After long and painful reflection, the following diagram was drawn up:
In addition to resistors that reduce the voltage from the injector, there is a voltage stabilizer here in order to power the controller from the on-board network, as well as on the advice of grandfather and good friend capacitors were added to smooth out possible voltage peaks, and a resistor “just in case” for each logical input. And yes, I decided to send signals from the injector and sensor to analog inputs, which I later did not regret at all, because in digital mode the analog inputs did not want to understand the difference between a closed and open nozzle, but in analog they showed very clearly different levels voltage. Perhaps this is a flaw in my scheme, but everything was done for the first time, blindly and without testing on a breadboard, in general, at random.
Following the diagram, I wrote down the layout of the printed circuit board (yes, I immediately rushed to print, because I didn’t really want to mess around with a bunch of wires on the circuit board):
The board was etched for the first time and with some technology violations, so the result came out so-so. But after tinning everything came back in order. I etched using a laser iron, learned from well-known videos on easyelectronics. After etching the board turned out like this:
To solder the elements onto the board, we had to make a lot of holes in it. I didn’t want to buy an expensive drill like a Dremel or similar, and in order to save a couple of thousand rubles, I made a micro drill from a motor and a collet clamp, which were bought at a radio store nearby:
After drilling holes, tinning and soldering, the board began to look like this:
Here I foolishly soldered an extra stabilizer, which was later replaced with a resistor.
After the product was ready, I began testing it in combat conditions, that is, directly on the car. To do this, at my request, the wires from the injector and sensor were routed into the cabin. For the microcontroller I wrote test program, which wrote raw data to the COM port - the number of pulses from the speed sensor and the milliseconds during which the injector was open. After sitting in the car with my laptop and seeing that the data corresponded to reality, I was incredibly happy and went home to write a working version of the program.
After two or three testing sessions, the program began to show valid data. At first I calculated average consumption according to the time interval (5-10 minutes), which caused an interesting effect: after five minutes of standing at a traffic light (not even a traffic jam, but a slight semblance), the kilometer consumption jumped to prohibitive values of 50-100 liters per 100 km. At first I was perplexed, but then I realized that this is a common thing, because the consumption is per kilometer, and I average it over time: the clock is ticking, gasoline is flowing, and the car is standing still. After that, I came up with the bright idea of averaging by mileage: in the current version, the program calculates how much gasoline was consumed in the last kilometer and shows how many liters will be consumed if you drive 100 km at the same pace. The “instant” flow rate is calculated as the average for the last second and is updated every second.
Source code (if anyone is interested) I
In one of the articles in the first issue of Radio magazine in 1986, a version of a device was described that allows control over the amount of liquid and its speed (in this case we are interested in car fuel) that flows in the main pipes.
Due to the high requirements for processing accuracy, certain difficulties may arise when repeating the described flow meter, as well as in the process of setting it up. The electronic unit of this device must be well protected from interference, due to the fact that the level of interference in the vehicle on-board network is quite high. This device has another drawback. The point is that as the fuel flow rate decreases, the measurement error inevitably increases.
The device described below does not have these disadvantages; its sensor design is simpler, as is the circuit of the electronic unit. This device does not have a device that monitors the rate of fuel consumption - a total consumption meter is designed for this function. The driver audibly perceives the rate of fuel consumption, which is proportional to the frequency of operation. In urban environments heavy traffic this is especially important because it does not distract the driver from driving the car.
What does a flow meter consist of?
The device has two units:
1. Sensor with electric valve.
2. Electronic unit.
The sensor is built into the fuel line and is located between the carburetor and the fuel pump. The electronic unit is located in the cabin. The figure shows the design of the sensor. 1 Elastic diaphragm 4 is sandwiched between pan 2 and body 8. It divides the internal volume into two cavities - lower and upper.
The guide sleeve 7 is made of fluoroplastic. The rod 5 moves freely in it. The diaphragm is clamped in its lower part using a nut and two washers 3. A permanent magnet 9 is installed at the upper end of the rod. Parallel to the channel where the rod is located, at the top of the body, there are 2 additional channels. These channels include two reed switches 10. One reed switch is activated when the magnet and diaphragm are in the lower position, the other – in the upper position.
Figure 1. 1-Fitting, 2 – Pan, 3- Washers, 4 – Diaphragm, 5- Rod, 6 – Spring, 7 – Bushing, 8 – Housing, 9 – Magnet, 10 – Reed switches
The diaphragm moves to the upper position due to the action of fuel pressure supplied from the fuel pump. It returns to the lower position using spring 6. In order for the sensor to be included in the fuel line, there are two fittings on the body and one on the pan. Fittings 3. The figure shows 2 the hydraulic diagram of the flow meter. Fuel from the fuel pump, through the solenoid valve and channel 3, begins to flow into channels 1, 2, filling the lower and upper cavities in the sensor. And it enters the carburetor through channel 4. The valve is switched under the influence of the electronic unit and the signals coming from it (not shown in this diagram). The electronic block is controlled by a reed switch installed in the sensor.
Puc.2 Hydraulic diagram of the fuel flow meter.
The winding of the solenoid valve is de-energized in the initial state, channels 3 and 1 communicate with each other, while channel 2 is closed. The diagram shows that the diaphragm is in the lower position. In the lower cavity 6, excess fluid pressure occurs with the help of a gasoline pump. The diaphragm will begin to gradually rise, as the engine produces fuel, from the upper cavity of the sensor, compressing the spring.
Reed switch 1 will operate when it reaches the top position, then the solenoid valve will open channel 2 and close channel 3. In this case, channel 1 is constantly open. The diaphragm will immediately move downward under the action of the compressed spring. It will return to its original position, passing fuel from cavity b to a, through channels 1 and 2. Then the cycle is repeated in the operation of the flow meter.
An electronic unit is connected to the electrovalve and sensor using a flexible cable through the XT1 connector. City committees SF1 and SF2 are installed in the sensor. According to the diagram, none of them is affected by a magnet. Transistor VT1 is closed in its initial position, the winding of the valve electromagnet Y1 is de-energized, 2 relays K1 are open. There is a sensor magnet next to the SF2 reed switch, so the reed switch does not conduct current.
Puc.3 Electronic unit of the fuel flow meter.
The magnet gradually moves, as fuel is consumed, between the reed switches SF2 and SF1, from cavity a of the sensor. At a certain moment, the SF2 reed switch switches, but this will not cause any changes in the block. The magnet, at the end of the stroke, switches the reed switch SF1, and the base current of the transistor VT1 will flow through the resistor R2 through the reed switch SF1. The transistor opens, relay K1 is activated, and turns on the valve solenoid with contacts K1.2. In this case, the power supply circuit of the pulse counter E1 will be closed by contacts K1.1.
As a result, the magnet and diaphragm will quickly move downward. At a certain moment, after reverse switching, the reed switch SF1 opens the base current circuit of the transistor. At the same time, it remains open, since now the base current flows through the diode VD2, the closed contacts K1.1 and the reed switch SF2. This is the reason why the rod with magnet and diaphragm continue to move.
The magnet switches reed switch SF2 at the end of the return stroke. After this, the counter E1 and the electromagnet Y1 of the valve will turn off, the transistor will close and the system returns to its original state, after which it is ready for a new operating cycle. As you can see, the number of cycles is recorded by counter E1. In this case, one cycle corresponds to a particular volume of fuel equal to the volume of space limited by the diaphragm located in the lower and upper positions.
By multiplying the volume of fuel used during one cycle by the meter readings, the fuel consumption is determined, which is set during calibration of the sensor. To make it more convenient to calculate the fuel consumed per cycle, its volume is equal to 0.01 liters. This volume can be changed by increasing or decreasing, while changing the height distance between the reed switches.
The optimal diaphragm stroke, given the existing sensor dimensions, is about 10 mm. The duration of the sensor cycle ranges from 6 to 30 s, and depends on the engine operating mode. When calibrating it, you should disconnect the pipeline from the gas tank, inserting it into a measuring vessel filled with fuel, then you need to start the engine to produce a certain amount of fuel - divide it by the number of cycles (determined by the meter), and as a result we get the number of a unit volume of fuel , consumed in one cycle.
The ability to disable it is provided in the flow meter using toggle switch SA1. In this case, fuel will flow into the carburetor directly, through cavity a, through channels 2 and 3, since the sensor diaphragm will always be in the lower position at this time. To turn off the device’s solenoid valve, you will have to remove the rubber cuff blocking channel 3, however, the error of the flow meter will worsen. The electronic unit is mounted on a printed circuit board made of fiberglass - a 1.5 mm thick plate. Its drawing is shown in Figure 4. The parts installed on the board are circled with dash-dot lines in the diagram. The board is mounted in a metal box. Its mounting is made under the instrument panel in the car interior.
Puc.4 Drawing of the fuel flow meter electronic unit board
What was used in the device:
– Relay RES9
– Electrovalve – P-RE 3/2.5-1112
– Passport PC4.529.029.11
– Counter SI-206 or SB-1M.
- Permanent magnet.
In this case, you can take any magnet, where the length is 18...20 mm, and the poles have an end arrangement. It is important that the magnet can move freely within its channel without affecting the walls. The magnet from the RPS32 remote switch is quite suitable for this, but you will have to grind it down to the required size. The sensor pan and body are machined from any material with non-magnetic and petrol-resistant properties.
Between the magnet and reed switch channels, the wall thickness should be up to 1 mm, the hole depth under the magnet should be 45 mm, and the diameter should be 5.1+0.1 mm. The rod is made of steel 45 or brass, the length of the threaded part is 8 mm, the diameter is 5 mm, the total length is 48 mm. The thread on the sensor fittings is M8; hole with a diameter of 5 mm. The solenoid valve fittings have a conical thread K 1/8″ GOST 6111-52.
A spring with a diameter of 0.8 mm, made of steel wire, GOST 9389-75 is used. Full compression force – 300...500 g, spring diameter – 15 mm, length – 70 mm, pitch – 5 mm. In the case where the rod is made of steel, the magnet itself is held on it.
When the rod is made of non-magnetic metal, it is necessary to strengthen the magnet in another way. To ensure that the compressed air pressure does not interfere with the operation of the sensor, a bypass channel with a cross-section of about 2 sq. mm should be provided in the bushing. The diaphragm is made of 0.2 mm polyethylene. It will have to be molded before installation in the sensor. A sensor tray can be used for these purposes.
Made from sheet duralumin 5 mm. a pressure ring should be made that matches the shape of the pallet flange. To form the diaphragm, the rod, complete with its workpiece, is inserted into the hole in the pan fitting from the inside, and the entire workpiece is clamped with a technological ring.
Next, the assembly is heated evenly from the diaphragm side, holding it at a distance of 60...70 cm from the burner flame. The diaphragm is formed by slightly raising the rod. So that it does not lose elasticity in the future, it must be in the fuel constantly. Therefore, you will have to pinch the hose to the carburetor when parking the car for a long time. This will prevent gasoline from evaporating.
An electric valve and sensor are installed in the engine compartment. They are mounted near the fuel pump and carburetor on a bracket, connecting with a cable to the electronic unit. Using a pump with a pressure gauge, you can check the performance of the flow meter without installing it on the car.
In this case, a pressure gauge is connected instead of a fuel pump. The sensor is triggered at a pressure of 0.1 ... 0.15 kg/cm 2. The flow meter was tested on Zhiguli and Moskvich cars. During the inspection, it was found that the engine operating mode does not in any way affect the accuracy of fuel consumption readings. The exact flow rate is determined by calculating the error in setting a single volume when calibrated to 1.5...2%.
