CN205559110U - Measurable exhaust gas flow's venturi - Google Patents

Abstract

The utility model relates to a venturi especially relates to a measurable exhaust gas flow's venturi. Including EGR outlet duct, venturi, EGR outlet duct, temperature sensor, pressure sensor, differential pressure sensor, venturi divide into consecutive venturi entry, venturi aditus laryngis and venturi flaring section, be provided with the pressure sensor passageway on the venturi entry, link to each other with pressure sensor, the position that the venturi entry is close to the venturi aditus laryngis is provided with entry ressure measurement passageway, and the venturi aditus laryngis links to each other with aditus laryngis ressure measurement passageway, entry ressure measurement passageway and aditus laryngis ressure measurement passageway communicate with differential pressure sensor respectively. This device is through venturi import cross -section and wait pressure differential, the gas density in mouthful cross -section, utilizes bernoulli equation, thereby it obtains mass flow to calculate the gaseous volume flow rate of the pipeline of flowing through, realizes EGR system flow closed -loop control.

Description

A Venturi Tube Measuring the Flow of Exhaust Gas

technical field

The utility model relates to a Venturi tube, in particular to a Venturi tube capable of measuring the flow rate of exhaust gas.

Background technique

Venturi: It is the abbreviation of Venturi tube. The principle of Venturi effect is that when the wind blows through the barrier, the air pressure near the port above the leeward side of the barrier is relatively low, resulting in adsorption and causing the air flow. The principle of the Venturi tube is actually very simple. It is to change the air flow from thick to thin to speed up the gas flow rate, so that the gas forms a "vacuum" area on the back side of the Venturi tube outlet.

The application of Venturi in the patent "Exhaust Gas Recirculation Device of Venturi Tube for Supercharged Diesel Engine" solves the problem that the recirculated exhaust gas of the high-pressure EGR system cannot enter the intake pipe under some working conditions, and there is a problem of backflow of exhaust gas, and realizes the exhaust gas recirculation under all working conditions. Better EGR rate. In the paper "Study on Improving EGR Rate of Diesel Engine Using Venturi Tube and VNT", Venturi is used to achieve the purpose of increasing EGR rate. In "Design and Test of Venturi Tube for EGR System of Supercharged Intercooled Diesel Engine", the throat diameter of Venturi tube is determined to increase the EGR rate.

However, no matter in the retrieved papers or patents, they all describe the purpose of using Venturi to achieve a higher EGR rate, and there is no content that can measure the flow rate of exhaust gas.

Utility model content

The utility model uses the Bernoulli equation to calculate the gas volume flow rate flowing through the pipeline through the pressure difference and gas density of the inlet section of the Venturi tube and the waiting port section, thereby obtaining the mass flow rate and realizing the flow closed-loop control strategy of the EGR system. A design that can use the design of the airway to sense and measure exhaust backflow.

In order to achieve the above objectives, the utility model adopts the following technical solutions, a venturi tube that can measure the flow of exhaust gas, including EGR outlet pipe, venturi tube, EGR outlet pipe II, temperature sensor, pressure sensor, differential pressure sensor; The trachea and the EGR outlet pipe II are respectively connected to both ends of the Venturi tube; the temperature sensor is set on the EGR outlet pipe; the Venturi tube is divided into a Venturi tube inlet, a Venturi tube throat, and a Venturi tube gradual expansion section connected in sequence; The inlet of the Venturi tube is provided with a pressure sensor channel, which is connected to the pressure sensor; the inlet of the Venturi tube is provided with an inlet pressure measurement channel near the throat of the Venturi tube, and the throat of the Venturi tube is connected with the throat pressure measurement channel; the inlet pressure The measuring channel and the throat pressure measuring channel are respectively communicated with the differential pressure sensor.

Further, a cooling device is arranged outside the Venturi tube, and the cooling device is placed on the support; one end of the cooling device is connected to the cooling water inlet pipe, and the other end is connected to the cooling water outlet pipe.

Further, the EGR outlet pipe is the outlet of the EGR cooler and is connected to the inlet of the Venturi pipe; the expanding section of the Venturi pipe is connected to the EGR outlet pipe II.

The utility model is a special Venturi tube, which uses the Bernoulli equation to convert the collected pressure, temperature and differential pressure signals into EGR waste gas flow, thereby realizing precise control of the EGR valve.

The Venturi tube of the utility model is arranged between the outlet of the EGR cooler and the intake pipe, and the applied system is an exhaust gas recirculation system. The exhaust gas is discharged from the exhaust pipe, and most of the exhaust gas enters the turbocharger to do work, and a small part passes through the exhaust gas recirculation system. Transfer to the air intake to participate in a new round of combustion.

The utility model has the advantages of:

1. Compared with the existing Venturi tube technology, the utility model adds the application of three kinds of sensors, which are used to measure the exhaust gas flow rate, and can measure the exhaust pipe backflow condition. Through calibration, the exhaust pipe backflow can be measured. To prevent the opening of the EGR valve in the case of exhaust backflow; at the same time, the accurate exhaust gas flow can be obtained through calculation, which can be used to control the opening of the EGR valve according to the calibration.

2. Compared with the existing Venturi tube, the utility model has more air passages and cooling water passages in terms of manufacturing.

3. It is integrally formed, no redundant parts are required, and the pipeline has strong adaptability; the utility model integrates brackets, pressure channels, pressure difference channels, and cooling water channels into one body, reducing assembly parts and simplifying the process flow.

The structure of this utility model was originally used in a 7L machine product of the company, and can be extended to all models. Compared with the control measurement of the measurement of the intake air flow, the control method using this product has strong anti-pollution ability, low requirements for pipeline installation, and simple calibration. ,reduce workload.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the appended drawings in the following description The drawings show some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without creative work.

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the structural representation of the utility model Venturi tube;

In the figure, 1-EGR outlet pipe, 2-Venturi tube, 21-Venturi tube inlet, 22-Venturi tube throat, 23-Venturi tube expansion section, 24-throat pressure measurement channel, 25-inlet pressure Measuring channel, 26-pressure sensor channel, 3-EGR outlet pipe II, 4-temperature sensor, 5-pressure sensor, 6-differential pressure sensor, 7-cooling water inlet pipe, 8-cooling water outlet pipe, 9-bracket.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the utility model more clear, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the utility model. Obviously, the described The embodiments are some embodiments of the present utility model, but not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Example 1:

Calculation principle of exhaust gas volume:

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}}}\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; \&rho;</span>}}$

In the formula:

Q _m ——mass flow rate, the mass of exhaust gas passing through Venturi tube 2 per unit time, unit kg/s;

C——Outflow coefficient, which represents the coefficient of the relationship between the actual flow through the device and the theoretical flow;

β—diameter ratio, the ratio of the diameter of the Venturi throat 22 to the inlet diameter;

ε—expansion coefficient;

d——throat diameter, venturi throat diameter, unit m;

Δp——Pressure difference, the static pressure difference measured between the Venturi tube inlet 21 and the throat, the signal is measured by the HCM pressure difference sensor, the unit is Pa;

ρ——exhaust gas density, calculated by exhaust gas temperature and pressure, unit kg/m ³ .

According to calculation requirements, the Venturi tube system needs three sensors, as shown in Figure 1, a Venturi tube that can measure the flow of exhaust gas, including EGR outlet pipe 1, Venturi pipe 2, EGR outlet pipe II 3, temperature sensor 4, The pressure sensor 5 and the differential pressure sensor 6; the EGR outlet pipe 1 and the EGR outlet pipe II 3 are respectively connected to both ends of the Venturi pipe 2; the temperature sensor 4 is arranged on the EGR outlet pipe 1.

The working principle of the EGR system is to use the pressure difference, that is, the exhaust gas pressure is higher than the intake pressure, so that the exhaust gas mixes with the fresh air and enters the cylinder again for combustion. There is a problem of exhaust gas backflow in the air pipe. In this case, the ordinary Venturi tube can still measure a positive value. At this time, the calculated flow rate should be a negative number, but the system cannot distinguish it. The EGR valve opening adjusted according to this state is bound to be it is wrong. At the same time, the utility model can solve the miscalculation caused by the backflow of the exhaust pipe.

Venturi tube of the utility model is shown in Figure 2, and Venturi tube 2 is divided into successively connected Venturi tube inlet 21, Venturi tube throat 22 and Venturi tube gradual expansion section 23; Venturi tube inlet 21 is provided with The pressure sensor channel 26 is connected with the pressure sensor 5; the position of the Venturi tube inlet 21 near the Venturi tube throat 22 is provided with an inlet pressure measurement channel 25, and the Venturi tube throat 22 is connected with the throat pressure measurement channel 24; the inlet pressure The measuring channel 25 and the throat pressure measuring channel 24 communicate with the differential pressure sensor 6 respectively.

When the exhaust gas flows in the forward direction, since the throat pressure measuring channel 24 follows the air flow, the gas pressure is smaller than the pressure measured by the inlet pressure measuring channel 25, forming a positive pressure difference. On the contrary, when the exhaust gas flows in the opposite direction, since the throat pressure measurement channel 24 is facing the air flow, the pressure difference will often increase at this time, and the EGR valve can be closed according to the calibration to prevent misjudgment.

A cooling device is arranged outside the Venturi tube 2, and the cooling device is placed on the bracket 9; one end of the cooling device is connected with the cooling water inlet pipe 7, and the other end is connected with the cooling water outlet pipe 8.

The EGR outlet pipe 1 is the outlet of the EGR cooler and is connected to the inlet 21 of the Venturi pipe; the expanding section 23 of the Venturi pipe is connected to the EGR outlet pipe II3.

Claims (3)

1. A Venturi tube capable of measuring exhaust gas flow, characterized in that it comprises an EGR outlet pipe (1), a Venturi pipe (2), an EGR outlet pipe II (3), a temperature sensor (4), a pressure sensor (5 ), a differential pressure sensor (6); the EGR outlet pipe (1) and the EGR outlet pipe II (3) are respectively connected to both ends of the Venturi tube (2); the temperature sensor (4) is arranged on the EGR outlet pipe (1); The Venturi tube (2) is divided into a Venturi tube inlet (21), a Venturi tube throat (22) and a Venturi tube gradual expansion section (23) connected in sequence; a pressure sensor is arranged on the Venturi tube inlet (21) Passage (26), links to each other with pressure sensor (5); Venturi tube inlet (21) is provided with inlet pressure measuring channel (25) near Venturi tube throat (22), and Venturi tube throat (22) and The throat pressure measurement channel (24) is connected; the inlet pressure measurement channel (25) and the throat pressure measurement channel (24) are respectively communicated with the differential pressure sensor (6). 2. The Venturi tube of measurable exhaust gas flow as claimed in claim 1, is characterized in that: Venturi tube (2) outside is provided with cooling device, and cooling device is placed on the support (9); Cooling device one end and cooling water The water inlet pipe (7) links to each other, and one end links to each other with the cooling water outlet pipe (8). 3. the Venturi tube of measurable exhaust gas flow as claimed in claim 1, is characterized in that: EGR outlet pipe (1) is the outlet of EGR cooler, links to each other with Venturi tube inlet (21); Venturi tube gradual expansion section (23) is connected with EGR outlet pipe II (3).