阅读说明：本技术 一种燃料电池汽车尾气混合系统及其控制方法 (Fuel cell automobile exhaust mixing system and control method thereof ) 是由 吴星成 贺翀 王子剑 陈明 王波 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种燃料电池汽车尾气混合系统及其控制方法,混合系统包括阳极尾气管道、阴极尾气管道、稀释气体管道、尾气混合器、混合排放管、控制器,所述尾气混合器内设有沿气体流向设置的混合腔室和消音腔室,所述阳极尾气管道、阴极尾气管道均与混合腔室连接,所述稀释气体管道与阴极尾气管道连接,所述混合排放管与消音腔室连接,所述稀释气体管道上设有调节阀,所述阴极尾气管道上设有单向阀,所述阳极尾气管道上设有第一氢浓度传感器,所述混合排放管上设有第二氢浓度传感器。本发明混合系统中采用了稀释气体管道通入稀释气体,稀释气体、阳极尾气、阴极尾气在尾气混合器内混合后排出,降低氢排放浓度,较大提升了整车氢安全。(The invention discloses a fuel cell automobile exhaust mixing system and a control method thereof, wherein the mixing system comprises an anode exhaust pipeline, a cathode exhaust pipeline, a diluent gas pipeline, an exhaust mixer, a mixing discharge pipe and a controller, a mixing chamber and a silencing chamber are arranged in the exhaust mixer along the gas flow direction, the anode exhaust pipeline and the cathode exhaust pipeline are both connected with the mixing chamber, the diluent gas pipeline is connected with the cathode exhaust pipeline, the mixing discharge pipe is connected with the silencing chamber, an adjusting valve is arranged on the diluent gas pipeline, a one-way valve is arranged on the cathode exhaust pipeline, a first hydrogen concentration sensor is arranged on the anode exhaust pipeline, and a second hydrogen concentration sensor is arranged on the mixing discharge pipe. The mixing system adopts the diluent gas pipeline to introduce the diluent gas, and the diluent gas, the anode tail gas and the cathode tail gas are mixed in the tail gas mixer and then discharged, thereby reducing the hydrogen emission concentration and greatly improving the hydrogen safety of the whole vehicle.)

1. A fuel cell automobile exhaust mixing system is characterized by comprising an anode exhaust pipeline (1), a cathode exhaust pipeline (2), a diluent gas pipeline (3), an exhaust mixer (4) and a controller (10),

tail gas blender (4) are including mixing chamber (41) and amortization cavity (42) that set up along the gas flow direction, positive pole tail gas pipeline (1), negative pole tail gas pipeline (2) all are connected with mixing chamber (41) and are used for introducing mixing chamber (41) with fuel cell's (20) positive pole tail gas, negative pole tail gas and mix, dilution gas pipeline (3) are connected with negative pole tail gas pipeline (2) and are used for drawing forth part to negative pole tail gas pipeline (2) with the fresh air that flows to fuel cell (20) cathode inlet.

2. The fuel cell automobile exhaust gas mixing system according to claim 1, further comprising a mixing exhaust pipe (5), wherein the mixing exhaust pipe (5) is connected to the silencing chamber (42) for exhausting the silenced mixed exhaust gas to the atmosphere, the diluent gas pipe (3) is provided with a regulating valve (6), the cathode exhaust gas pipe (2) is provided with a check valve (7) in front of the connection of the diluent gas pipe (3), the anode exhaust gas pipe (1) is provided with a first hydrogen concentration sensor (8), the mixing exhaust pipe (5) is provided with a second hydrogen concentration sensor (9), and the first hydrogen concentration sensor (8), the second hydrogen concentration sensor (9) and the regulating valve (6) are electrically connected to the controller (10).

3. The fuel cell automobile exhaust gas mixing system according to claim 2, wherein the mixing chamber (41) is coaxially arranged with the sound deadening chamber (42) and the inner diameter of the sound deadening chamber (42) is larger than the inner diameter of the mixing chamber (41), the axial length of the sound deadening chamber (42) is larger than the axial length of the mixing chamber (41), the mixing chamber (41) is provided with a first inlet (44) and a second inlet (45) at the front end and a communication hole (43) at the rear end for communicating with the sound deadening chamber (42);

the cross-sectional flow area of the communication hole (43) is larger than either of the cross-sectional flow area of the first inlet (44) and the cross-sectional flow area of the second inlet (45), and the cross-sectional flow area of the communication hole (43) is smaller than the sum of the cross-sectional flow area of the first inlet (44) and the cross-sectional flow area of the second inlet (45).

4. A fuel cell automobile exhaust gas mixing system according to claim 3, wherein the rear end of the sound-deadening chamber (42) is provided with a mixing outlet (47) connected to the mixing exhaust pipe (5), the sound-deadening chamber (42), the mixing outlet (47) and the communication hole (43) are coaxially arranged, the inner wall of the sound-deadening chamber (42) is provided with a plurality of sound-deadening plates (46), the sound-deadening plates (46) are axially arranged at intervals, adjacent sound-deadening plates (46) are diametrically opposite to each other on the inner wall of the sound-deadening chamber (42), each sound-deadening plate (46) extends toward the center along the radial direction or is inclined backward, and the sound-deadening plates (46) extend toward the center to the end at the center axis of the sound-deadening chamber (42) or beyond the center axis of the sound-deadening chamber (42).

5. The fuel cell automobile exhaust gas mixing system according to claim 3, wherein the inlet of the anode exhaust gas pipe (1) is connected with the anode outlet of the fuel cell (20), the outlet of the anode exhaust gas pipe is connected with the first inlet (44) on the mixing chamber (41), the inlet of the cathode exhaust gas pipe (2) is connected with the cathode outlet of the fuel cell (20), the outlet of the cathode exhaust gas pipe is connected with the second inlet (45) on the mixing chamber (41), the inlet of the diluent gas pipe (3) is connected with the cathode inlet pipe (21) for supplying fresh air to the cathode inlet of the fuel cell (20), and the outlet of the diluent gas pipe is connected with the cathode exhaust gas pipe (2).

6. A fuel cell automobile exhaust mixed control method is characterized by comprising the following steps:

the method comprises the following steps that firstly, a fuel cell (20) starts to operate, anode tail gas and cathode tail gas of the fuel cell (20) enter a tail gas mixer (4) through an anode tail gas pipeline (1) and a cathode tail gas pipeline (2) respectively, diluent gas is introduced into the cathode tail gas pipeline (2), the flow of the diluent gas is controlled to be a preset flow, the diluent gas, the anode tail gas and the cathode tail gas are mixed in the tail gas mixer (4), mixed gas in the tail gas mixer (4) is discharged into the atmosphere through a mixing discharge pipe (5), and the hydrogen concentration on the anode tail gas pipeline (1) and the mixing discharge pipe (5) is monitored in real time;

step two, judging the magnitude relation between the hydrogen concentration value P1 on the anode tail gas pipeline (1) and a first preset limit value a, and if P1 is larger than a, carrying out the next step;

step three, calculating the hydrogen concentration increment delta P1 as P1-a, judging the size relation between the hydrogen concentration P2 on the mixing discharge pipe (5) and a second preset limit value b, and if the hydrogen concentration P2 is not more than b, keeping the flow rate of the diluent gas as the preset flow rate; if P2 > b, increasing the flow of the diluent gas according to the calculated hydrogen concentration increment delta P1 until the hydrogen concentration P2 on the mixing discharge pipe (5) is not more than b, and then carrying out the next step;

and step four, judging the relation between the hydrogen concentration value P1 on the anode tail gas pipeline (1) and a first preset limit value a, returning to the step three if P1 is larger than a, and controlling the flow of the diluent gas to recover the preset flow if P1 is not larger than a.

7. The fuel cell automobile exhaust gas mixing control method according to claim 6, characterized in that in the first step, the diluent gas is introduced into the cathode exhaust gas pipe (2) from the diluent gas pipe (3), and the diluent gas pipe (3) is used for leading out part of the fresh air flowing to the cathode inlet of the fuel cell (20) to the cathode exhaust gas pipe (2).

8. The fuel cell vehicle exhaust gas mixing control method according to claim 7, wherein in the first step, the controlling of the flow rate of the diluent gas to a preset flow rate specifically comprises: the opening degree of the adjusting valve (6) arranged on the diluent gas pipeline (3) is controlled to be a preset opening degree, and the adjusting valve (6) is used for adjusting the flow of the diluent gas.

9. The fuel cell automobile exhaust gas mixing control method according to claim 8, wherein in the third step, the step of maintaining the flow rate of the diluent gas at the preset flow rate specifically comprises: the opening degree of the regulating valve (6) is kept to be a preset opening degree.

10. The fuel cell automobile exhaust gas mixing control method according to claim 8, wherein in step three, increasing the flow rate of the diluent gas in accordance with the hydrogen concentration increase Δ P1 is specifically: the opening degree of the regulating valve (6) is increased according to the hydrogen concentration increase amount DeltaP 1.

Technical Field

The invention relates to a new energy automobile, in particular to a fuel cell automobile exhaust gas mixing system and a control method thereof.

Background

In order to better cope with the national environmental problem and the energy problem, the hydrogen fuel cell automobile is one of the development strategies of countries in the world. The power source of a hydrogen fuel cell vehicle is derived from a fuel cell engine, which is a power generation device that converts chemical energy into electrical energy by a chemical reaction between hydrogen gas entering through an anode and oxygen-containing gas (usually air) entering through a cathode via a catalyst. With the continuous and wide application of hydrogen fuel cell vehicles, more and more problems are shown. With the operation of the fuel cell, hydrogen enters the exhaust pipe along with exhaust gas (tail gas) and is finally exhausted to the atmosphere, and the low density characteristic of the hydrogen enables the hydrogen to be easily accumulated in the exhaust pipe, so that the accumulated hydrogen has the risk of explosion due to the sharp increase of the hydrogen concentration in a local area in the exhaust pipe or after the accumulated hydrogen is exhausted. Therefore, it is necessary to control the hydrogen concentration in the exhaust gas of the hydrogen fuel cell vehicle within the allowable knock threshold range, including the local hydrogen concentration in the exhaust pipe and the overall concentration outside the exhaust vehicle. In addition, compared with the traditional automobile, the engine noise of the hydrogen fuel cell automobile is much smaller, but the exhaust noise caused by the operation of the air compressor is prominent, so that the riding comfort of a user is greatly influenced, and the problem is urgently needed to be solved. Meanwhile, the space of the fuel cell passenger car is small, and the mixer and the silencer are dispersedly arranged to cause space waste, which is not beneficial to saving space.

Chinese patent publication No. CN110026101A discloses an exhaust mixing device for a hydrogen fuel cell vehicle, in which a front swirl vane and a rear swirl vane inside a hydrogen mixer make it have a swirl effect, so as to uniformly mix hydrogen and water vapor. However, the patent only aims at uniformly mixing the hydrogen, if the content of the hydrogen in the mixed gas originally exceeds the threshold range, the content of the hydrogen is uniformly mixed and also exceeds the threshold range, the patent does not have any function of diluting and adjusting the hydrogen concentration, and the content of the discharged hydrogen cannot be always ensured to be within the threshold range.

Therefore, it is required to develop a fuel cell automobile exhaust gas hybrid system having a simple structure, capable of adjusting the hydrogen concentration of the exhaust gas in the exhaust line, and having a noise reduction function, and a control method thereof.

Disclosure of Invention

The present invention aims to solve the above-mentioned drawbacks of the background art and provide a fuel cell automobile exhaust gas mixing system with simple structure, adjustable hydrogen concentration of the exhaust gas line and noise reduction function, and a control method thereof.

The technical scheme of the invention is as follows: a fuel cell automobile exhaust mixing system is characterized by comprising an anode exhaust pipeline, a cathode exhaust pipeline, a diluent gas pipeline, an exhaust mixer and a controller,

the tail gas mixer comprises a mixing chamber and a silencing chamber which are arranged along the gas flow direction, the anode tail gas pipeline and the cathode tail gas pipeline are connected with the mixing chamber and used for introducing anode tail gas and cathode tail gas of the fuel cell into the mixing chamber for mixing, and the diluting gas pipeline is connected with the cathode tail gas pipeline and used for leading out a part of fresh air flowing to the cathode inlet of the fuel cell to the cathode tail gas pipeline.

Preferably, still include the mixed delivery pipe, the mixed delivery pipe is connected with the amortization cavity and is used for discharging the mixed tail gas after the amortization into the atmosphere, be equipped with the governing valve on the diluent gas pipeline, be equipped with the check valve in diluent gas pipeline junction the place ahead on the cathode tail gas pipeline, be equipped with first hydrogen concentration sensor on the anode tail gas pipeline, be equipped with second hydrogen concentration sensor on the mixed delivery pipe, first hydrogen concentration sensor, second hydrogen concentration sensor, governing valve all with controller electric connection.

Furthermore, the mixing chamber and the silencing chamber are coaxially arranged, the inner diameter of the silencing chamber is larger than that of the mixing chamber, the axial length of the silencing chamber is larger than that of the mixing chamber, the front end of the mixing chamber is provided with a first inlet and a second inlet, and the rear end of the mixing chamber is provided with a communicating hole for communicating with the silencing chamber;

the communication hole has a flow cross-sectional area larger than either of the flow cross-sectional area of the first inlet and the flow cross-sectional area of the second inlet, and smaller than the sum of the flow cross-sectional area of the first inlet and the flow cross-sectional area of the second inlet.

Furthermore, the rear end of the silencing cavity is provided with a mixing outlet connected with a mixing discharge pipe, the silencing cavity, the mixing outlet and the communication hole are coaxially arranged, the inner wall of the silencing cavity is provided with a plurality of silencing plates, the silencing plates are axially arranged at intervals, adjacent silencing plates are opposite to each other in the radial direction on the inner wall of the silencing cavity, each silencing plate extends towards the center in the radial direction or inclines backwards towards the center, and the silencing plates extend towards the center to the end part to be located at the central axis of the silencing cavity or exceed the central axis of the silencing cavity.

Furthermore, the inlet of the anode tail gas pipeline is connected with the outlet of the anode of the fuel cell, the outlet of the anode tail gas pipeline is connected with the first inlet of the mixing chamber, the inlet of the cathode tail gas pipeline is connected with the outlet of the cathode of the fuel cell, the outlet of the cathode tail gas pipeline is connected with the second inlet of the mixing chamber, the inlet of the diluent gas pipeline is connected with the cathode gas inlet pipeline which provides fresh air for the inlet of the cathode of the fuel cell, and the outlet of the diluent gas pipeline is connected with the cathode tail gas pipeline.

The invention also provides a fuel cell automobile exhaust mixed control method, which is characterized by comprising the following steps:

the method comprises the following steps that firstly, a fuel cell starts to operate, anode tail gas and cathode tail gas of the fuel cell enter a tail gas mixer through an anode tail gas pipeline and a cathode tail gas pipeline respectively, diluent gas is introduced into the cathode tail gas pipeline, the flow of the diluent gas is controlled to be a preset flow, the diluent gas, the anode tail gas and the cathode tail gas are mixed in the tail gas mixer, mixed gas in the tail gas mixer is discharged into the atmosphere through a mixing discharge pipe, and the hydrogen concentration on the anode tail gas pipeline and the hydrogen concentration on the mixing discharge pipe are monitored in real time;

step two, judging the magnitude relation between the hydrogen concentration value P1 on the anode tail gas pipeline and a first preset limit value a, and if P1 is larger than a, carrying out the next step;

step three, calculating a hydrogen concentration increment delta P1 to P1-a, judging the size relation between the hydrogen concentration P2 on the mixing discharge pipe and a second preset limit value b, and if P2 is not more than b, keeping the flow rate of the diluent gas at a preset flow rate; if P2 > b, increasing the flow of the diluent gas according to the calculated hydrogen concentration increment delta P1 until the hydrogen concentration P2 on the mixing discharge pipe is not more than b, and then carrying out the next step;

and step four, judging the relation between the hydrogen concentration value P1 on the anode tail gas pipeline and a first preset limit value a, returning to the step three if P1 is larger than a, and controlling the flow of the diluent gas to recover the preset flow if P1 is not larger than a.

Preferably, in the first step, a dilution gas is introduced into the cathode tail gas pipeline from a dilution gas pipeline, and the dilution gas pipeline is used for leading out a part of fresh air flowing to the cathode inlet of the fuel cell to the cathode tail gas pipeline.

Further, in the step one, controlling the flow of the dilution gas to be the preset flow specifically comprises: the opening degree of the regulating valve arranged on the dilution gas pipeline is controlled to be a preset opening degree, and the regulating valve is used for regulating the flow of the dilution gas.

Further, in the third step, the step of keeping the flow rate of the dilution gas at the preset flow rate specifically comprises: and keeping the opening degree of the regulating valve at a preset opening degree.

Furthermore, in step three, the increasing of the flow rate of the dilution gas according to the hydrogen concentration increment Δ P1 is specifically as follows: the opening degree of the regulating valve is increased in accordance with the hydrogen concentration increase Δ P1.

The invention has the beneficial effects that:

1. the adoption dilutent gas pipeline lets in the diluent gas in the hybrid system, dilutes the hybrid gas when negative pole waste gas, positive pole waste gas mixed hydrogen concentration exceed standard, has solved because of the sharp increase of local region hydrogen concentration in the tail gas piping system or with the tail gas that contains high concentration hydrogen composition discharge into behind the atmosphere hydrogen gathering and the risk problem that arouses deflagration, has greatly promoted whole car hydrogen safety.

2. The tail gas mixer has a mixing function and a silencing function, and is combined with the exhaust silencer, so that the problem of space waste caused by the dispersed arrangement of the mixer and the silencer is solved.

3. Tail gas enters the mixing cavity for first mixing and dilution, the inner diameter of the mixing chamber is certainly larger than that of a gas pipeline, and the gas is expanded and diffused in the mixing chamber due to the size difference, so that energy is consumed, the gas flow rate is reduced, and the exhaust sound is reduced to a certain extent; the flow cross-sectional area of the communication hole in the mixing cavity is larger than any one of the flow cross-sectional area of the first inlet and the flow cross-sectional area of the second inlet, and is smaller than the sum of the flow cross-sectional area of the first inlet and the flow cross-sectional area of the second inlet, so that the communication hole causes certain obstruction to the outflow of the mixed gas, and the mixed gas is further uniformly mixed in the mixing cavity.

4. The intercommunicating pore makes the mist flow fast when the mist gets into the amortization chamber, and the acoustical panel can change airflow direction, reduce the velocity of flow with gaseous vortex dispersion, and exhaust noise has also obtained certain degree and has reduced, also can carry out the secondary with tail gas through the acoustical panel simultaneously and mix, ensures that gas mixture dilutes more evenly, discharges through the blender export at last.

5. In the control method, the hydrogen concentration in the anode waste gas pipeline can be monitored in real time, and once the hydrogen concentration exceeds a set safety threshold, the amount of diluent gas entering the mixer can be timely increased, so that the local hydrogen concentration and the integral hydrogen concentration discharged into the atmosphere can be quickly reduced.

6. In the control method, the hydrogen concentration on the mixed discharge pipe can be monitored in real time, and whether the hydrogen concentration of the mixed gas is reduced to be within a safety threshold value or not can be rapidly judged. Two hydrogen concentration sensors and governing valve cooperation, quick accurate adjust the gas flow that dilutes.

Drawings

FIG. 1 is a schematic view of an automobile exhaust gas mixing system of a fuel cell according to the present invention

FIG. 2 is a flow chart of control of the fuel cell automobile exhaust gas mixing system

Wherein: 1-anode tail gas pipeline 2-cathode tail gas pipeline 3-diluent gas pipeline 4-tail gas mixer 5-mixing discharge pipe 6-regulating valve 7-one-way valve 8-first hydrogen concentration sensor 9-second hydrogen concentration sensor 10-controller 20-fuel cell 21-cathode gas inlet pipeline 22-anode gas inlet pipeline 41-mixing chamber 42-silencing chamber 43-communication hole 44-first inlet 45-second inlet 46-silencing plate 47-mixing outlet.

Detailed Description

The following specific examples further illustrate the invention in detail.

As shown in fig. 1, a fuel cell automobile exhaust mixing system includes an anode exhaust pipe 1, a cathode exhaust pipe 2, a diluent gas pipe 3, an exhaust mixer 4, a mixing discharge pipe 5, and a controller 10, wherein a mixing chamber 41 and a silencing chamber 42 are arranged in the exhaust mixer 4 along a gas flow direction, the anode exhaust pipe 1 and the cathode exhaust pipe 2 are both connected with the mixing chamber 41 and used for introducing anode exhaust and cathode exhaust of a fuel cell 20 into the mixing chamber 41 for mixing, the diluent gas pipe 3 is connected with the cathode exhaust pipe 2 and used for leading out a fresh air flowing to a cathode inlet of the fuel cell 20 to the cathode exhaust pipe 2, and the mixing discharge pipe 5 is connected with the silencing chamber 42 and used for discharging the silenced mixed exhaust into the atmosphere. The fuel cell 20 is provided with a cathode inlet duct 21 communicating with the cathode inlet, and an anode inlet duct 22 communicating with the anode inlet. In this embodiment, the gas flow direction is from the front to the rear.

Be equipped with governing valve 6 on the diluent gas pipeline 3, be equipped with check valve 7 in diluent gas pipeline 3 junction the place ahead on the cathode tail gas pipeline 2, be equipped with first hydrogen concentration sensor 8 on the anode tail gas pipeline 1, be equipped with second hydrogen concentration sensor 9 on the mixed delivery pipe 5, first hydrogen concentration sensor 8, second hydrogen concentration sensor 9, governing valve 6 all with 10 electric connection of controller.

The mixing chamber 41 and the silencing chamber 42 are coaxially arranged, the inner diameter of the silencing chamber 42 is larger than that of the mixing chamber 41, the axial length of the silencing chamber 42 is larger than that of the mixing chamber 41, the axial front end of the mixing chamber 41 is provided with a first inlet 44 and a second inlet 45, and the rear end of the mixing chamber 41 is provided with a communication hole 43 for communicating with the silencing chamber 42. The flow cross-sectional area S1 of the communication hole 43 is larger than either of the flow cross-sectional area S2 of the first inlet 44 and the flow cross-sectional area S3 of the second inlet 45, and the flow cross-sectional area S1 of the communication hole 43 is smaller than the sum of the flow cross-sectional area S2 of the first inlet 44 and the flow cross-sectional area S3 of the second inlet 45. The cross-sectional area of the mixing chamber 41 is much larger than the flow cross-sectional area of the anode tail gas pipe 1 and much larger than the flow cross-sectional area of the cathode tail gas pipe 2.

The rear end of the sound attenuation chamber 42 is provided with a mixing outlet 47 connected with the mixing discharge pipe 5, the sound attenuation chamber 42, the mixing outlet 47 and the communication hole 43 are coaxially arranged, the inner wall of the sound attenuation chamber 42 is provided with a plurality of sound attenuation plates 46, the sound attenuation plates 46 are axially arranged at intervals, the adjacent sound attenuation plates 46 are opposite to each other in the radial direction on the inner wall of the sound attenuation chamber 42, each sound attenuation plate 46 extends towards the center in the radial direction or inclines towards the center in a backward direction, and the sound attenuation plates 46 extend towards the center to the end part at the central axis or beyond the central axis. In this embodiment, each sound-deadening plate 46 extends radially toward the center to the center axis of the sound-deadening chamber 42.

The inlet of the anode tail gas pipeline 1 is connected with the outlet of the anode of the fuel cell 20, the outlet of the anode tail gas pipeline is connected with a first inlet 44 on the mixing chamber 41, the inlet of the cathode tail gas pipeline 2 is connected with the outlet of the cathode of the fuel cell 20, the outlet of the cathode tail gas pipeline is connected with a second inlet 45 on the mixing chamber 41, the inlet of the diluent gas pipeline 3 is connected with a cathode gas inlet pipeline 21 which provides fresh air for the cathode inlet of the fuel cell 20, and the outlet of the diluent gas pipeline is connected with the cathode tail gas pipeline 2.

In this example, the diluent gas is fresh air, the check valve 7 is used to prevent the fresh air from the diluent gas pipe 3 from reversely entering the interior of the fuel cell from the cathode exhaust gas pipe 2, and the controller 10 is an existing fuel cell controller FCU.

The working principle of the fuel cell automobile exhaust mixing system is as follows:

diluent gas, cathode tail gas pass through second entry 45 and get into mixing chamber 41, and anode tail gas passes through first entry 44 and gets into mixing chamber 41, mixes the three for the first time and dilutes, because mixing chamber 41 cross-sectional area is far greater than 1 circulation sectional areas of anode tail gas pipeline, 2 circulation sectional areas of cathode tail gas pipeline, and gas is the expansion diffusion in mixing chamber 41, has reduced the gas flow rate, and the sound of exhausting also reduces to a certain extent. The communicating hole 43(S1 > S2, S1 > S3, and S1 < S2+ S3) provides a certain resistance to the outflow of the mixed gas, so that the mixed gas is further uniformly mixed in the mixing chamber 41. The intercommunicating pore 43 makes the gas mixture flow fast when the gas mixture enters the silencing chamber 42, and the silencing plate 46 disperses the gas turbulence to change the gas flow direction and reduce the flow rate, the exhaust noise is reduced to a certain degree, and simultaneously, the tail gas can be secondarily mixed through the silencing plate 46, so that the gas mixture is more uniformly diluted and finally discharged through the mixing discharge pipe 5.

As shown in fig. 2, the method for controlling the fuel cell automobile exhaust gas hybrid system includes the following steps:

step one, the fuel cell 20 starts to operate, anode tail gas and cathode tail gas of the fuel cell 20 enter a tail gas mixer 4 through an anode tail gas pipeline 1 and a cathode tail gas pipeline 2 respectively, diluent gas is introduced into the cathode tail gas pipeline 2 from a diluent gas pipeline 3, the diluent gas pipeline 3 is used for leading out part of fresh air flowing to a cathode inlet of the fuel cell 20 to the cathode tail gas pipeline 2, the flow of the diluent gas is controlled to be preset flow, namely the opening of an FCU control regulating valve 6 is controlled to be a preset opening K₀The adjusting valve 6 is used for adjusting the flow of the diluent gas on the diluent gas pipeline 3, the diluent gas, the anode tail gas and the cathode tail gas are mixed in the tail gas mixer 4, the mixed gas in the tail gas mixer 4 is discharged into the atmosphere through the mixing discharge pipe 5, and the FCU monitors the hydrogen concentration on the anode tail gas pipeline 1 and the mixing discharge pipe 5 in real time through the first hydrogen concentration sensor 8 and the second hydrogen concentration sensor 9 respectively;

secondly, the FCU judges the magnitude relation between the hydrogen concentration value P1 on the anode tail gas pipeline 1 and a first preset limit value a, the first preset limit value a is stored in the FCU in advance, and if P1 is larger than a, the next step is carried out;

step three, calculating the hydrogen concentration increment delta P1 to be P1-a by the FCU, judging the magnitude relation between the hydrogen concentration P2 on the mixing discharge pipe 5 and a second preset limit value b, wherein the second preset limit value b is stored in the FCU in advance,

if P2 is less than or equal to b, keeping the flow rate of the diluent gas at the preset flow rate, namelyThe FCU keeps the opening of the regulating valve 6 at a preset opening K₀The program is ended;

if P2 > b, increasing the flow of the diluent gas according to the obtained hydrogen concentration increment delta P1, namely, increasing the opening degree of the adjusting valve 6 by the FCU according to the hydrogen concentration increment delta P1 until the hydrogen concentration P2 on the mixing discharge pipe 5 is not more than b, and then carrying out the next step;

step four, judging the relation between the hydrogen concentration value P1 on the anode tail gas pipeline 1 and a first preset limit value a, if P1 is larger than a, returning to the step three, if P1 is not larger than a, controlling the flow of the diluent gas to recover to the preset flow, namely, the FCU recovers the opening of the regulating valve 6 to the preset opening K₀And the routine is ended.