CN114412671A

CN114412671A - Engine and control method thereof

Info

Publication number: CN114412671A
Application number: CN202210321909.1A
Authority: CN
Inventors: 徐帅卿; 李卫; 卫阳飞
Original assignee: Weichai Power Co Ltd
Current assignee: Weichai Power Co Ltd
Priority date: 2022-03-30
Filing date: 2022-03-30
Publication date: 2022-04-29

Abstract

The invention provides an engine and a control method thereof, wherein the engine comprises: a cylinder block having a cylinder; an air pipeline provided with a throttle valve; the air inlet pipe comprises an air inlet pipe body and a tail gas injection device, wherein an air outlet of the air pipeline is communicated with an air inlet of the tail gas injection device, an air outlet of the tail gas injection device is communicated with an air inlet of the air inlet pipe body, an air outlet of the air inlet pipe body is communicated with an air inlet of the air cylinder, the tail gas injection device comprises an injection pipe and an injection rod, and an air outlet of the air cylinder is communicated with an air inlet of the air exhaust pipe; the gas outlet of the exhaust pipe is communicated with the gas inlet of the EGR pipeline, the gas outlet of the EGR pipeline is communicated with the tail gas injection channel, and the EGR pipeline is provided with an EGR valve. Through the technical scheme provided by the application, the problem of how to improve the EGR rate of the engine on the premise of not influencing the economy of the engine in the related technology can be solved.

Description

Engine and control method thereof

Technical Field

The invention relates to the technical field of engines, in particular to an engine and a control method thereof.

Background

With the upgrading of emission regulations, the requirement of exhaust gas emitted by an engine is higher and higher. EGR (exhaust Gas recirculation) refers to a technique in which, after fuel and air are combusted in an engine of a vehicle, a portion of exhaust Gas is introduced back into intake air for re-combustion, so that nitrogen oxides in exhaust Gas can be reduced and the economy of the engine can be improved, and an EGR rate is used to represent the ratio of the amount of exhaust Gas circulated to the total intake air amount entering the engine.

In the correlation technique, in order to increase the injection capacity to tail gas, increase one at the EGR of the intake pipe of engine and draw and penetrate the pipe, utilize bernoulli's principle to draw tail gas to reduce the admission pressure of EGR access department in the intake pipe, with this increase EGR drive pressure differential, and then improve the EGR rate of heavy load.

The air inlet ejector pipe is adopted, high EGR rate can be achieved under the condition of a large load working condition, and the EGR system is simple in structure, low in cost and high in superiority. However, because the throat section of the injection pipe is fixed and unchanged, the throat section designed according to the requirements of large load and high EGR rate is adopted, when the requirement of small load and low EGR rate is met, the injection capacity of the tail gas is too strong, the throttle effect can be increased only by reducing the opening degree of the EGR valve, the EGR rate is reduced, the pressure of the tail gas can be utilized due to throttling, the air exchange efficiency of the engine is low, and the oil consumption is increased.

Disclosure of Invention

The invention provides an engine and a control method thereof, aiming at solving the problem of how to improve the EGR rate of the engine on the premise of not influencing the economy of the engine in the related art.

According to an aspect of the present invention, there is provided an engine including: a cylinder block having a cylinder; an air pipeline provided with a throttle valve; the air inlet pipe comprises an air inlet pipe body and a tail gas injection device, an air outlet of the air pipeline is communicated with an air inlet of the tail gas injection device, an air outlet of the tail gas injection device is communicated with an air inlet of the air inlet pipe body, an air outlet of the air inlet pipe body is communicated with an air inlet of the air cylinder, the tail gas injection device comprises an injection pipe and an injection rod, the injection pipe comprises a contraction section, a throat opening section and a diffusion section which are sequentially connected, in the direction that the contraction section points to the diffusion section, the size of the cross section of the contraction section is gradually reduced, the size of the cross section of the diffusion section is gradually increased, and a tail gas injection channel communicated with an inner hole of the throat opening section is arranged on the side wall of the injection pipe; the air outlet of the air cylinder is communicated with the air inlet of the exhaust pipe; the gas outlet of the exhaust pipe is communicated with the gas inlet of the EGR pipeline, the gas outlet of the EGR pipeline is communicated with the tail gas injection channel, and an EGR valve is arranged on the EGR pipeline; the tail gas injection device also comprises a detection piece for detecting the gas state of the injection pipe, and the control piece is electrically connected with the detection piece; wherein, draw and penetrate pole and include interconnect's this body section and circular cone section, the movably shrink section of wearing to locate of body section, the movably throat section of wearing to locate of circular cone section, on the directional diffusion section's of shrink section direction, the cross section size of circular cone section reduces gradually.

Furthermore, the tail gas injection device also comprises a driving motor, a motor shaft of the driving motor is in driving connection with one end, far away from the conical section, of the body section, and the throttle valve, the EGR valve and the driving motor are all electrically connected with the control piece.

Furthermore, the detection piece includes pressure sensor and temperature sensor, draws the ejector tube and still includes the inlet pipe section of being connected with the shrink section, and in the direction of the directional diffusion section of shrink section, the cross section size of inlet pipe section is unchangeable, and pressure sensor and temperature sensor all set up in the inlet pipe section.

Further, the detection member further includes a first flowmeter disposed on the EGR line and a second flowmeter disposed on the air line.

Further, the diffusion angle of the diffusion section is equal to the cone angle of the conical section; and/or the diffuser section has a diffuser angle between 7 ° and 15 °.

Further, the cross-sectional dimension of the throat section is constant in the direction in which the constriction is directed towards the diffuser section.

Furthermore, the injection pipe also comprises an air outlet pipe section, the air outlet pipe section is connected with one end, far away from the throat section, of the diffusion section, and the size of the cross section of the air outlet pipe section is unchanged in the direction that the contraction section points to the diffusion section.

According to another aspect of the present invention, there is provided a control method of an engine for controlling the operation of the engine provided above, the control method of the engine comprising: setting a throttle valve and an EGR valve at preset opening degrees; acquiring a required EGR rate and an actual EGR rate; and comparing the required EGR rate with the actual EGR rate, and if the actual EGR rate does not meet the requirement, adjusting the opening of a throttle valve or the opening of an EGR valve or the opening of a throat section to enable the actual EGR rate to meet the requirement.

Further, the step of comparing the actual EGR rate with the required EGR rate, and if the actual EGR rate does not meet the requirement, adjusting the opening of the throttle valve or the opening of the EGR valve or the opening of the throat section so that the actual EGR rate meets the requirement specifically comprises: under the condition that the actual EGR rate is smaller than the required EGR rate, if the opening degree of the throat section does not reach the minimum position, reducing the opening degree of the throat section to enable the actual EGR rate to meet the requirement, and if the opening degree of the throat section reaches the minimum position, reducing the opening degree of the throttle valve to enable the actual EGR rate to meet the requirement; under the condition that the actual EGR rate is greater than the required EGR rate, if the opening degree of the throat section does not reach the maximum position, the opening degree of the throat section is increased so that the actual EGR rate meets the requirement, and if the opening degree of the throat section reaches the maximum position, the opening degree of the EGR valve is reduced so that the actual EGR rate meets the requirement.

Further, before the step of comparing the required EGR rate with the actual EGR rate, the control method of the engine further includes: and acquiring the minimum opening degree of the throat section according to the operating condition of the engine and the gas state detected by a detection piece of the engine.

By applying the technical scheme of the invention, when the engine works, air enters the air inlet of the tail gas injection device from the air pipeline, enters the air inlet pipe body from the air outlet of the tail gas injection device and enters the cylinder of the cylinder body. The tail gas enters the exhaust pipe from the cylinder, enters the EGR pipeline from the exhaust pipe, enters the tail gas injection channel of the tail gas injection device from the EGR pipeline, and enters the throat section from the tail gas injection channel, because the conical section of the injection rod of the tail gas injection device can movably penetrate through the throat section, the size of the cross section of the conical section is gradually reduced in the direction of the contraction section pointing to the diffusion section, in the moving process of the conical section, the area of the cross section between the conical section and the throat section can be increased or decreased, when the engine is under a large-load working condition, the control element can send out a control signal, the control signal is transmitted to the driving motor, the driving motor drives the injection rod to move, so that the conical section moves towards the direction close to the diffusion section, the area of the cross section between the conical section and the throat section is decreased, further, the pressure of the gas in the throat section is decreased, the driving pressure difference of the tail gas is increased, and the EGR rate of the engine is improved, when the engine is in a small-load working condition, the control piece can send out a control signal, the control signal is transmitted to the driving motor, the driving motor drives the injection rod to enable the conical section to move towards the direction close to the contraction section, the cross section area between the conical section and the throat opening section is increased, the pressure of gas in the throat opening section is further increased, the driving pressure difference of tail gas is reduced, and therefore the EGR rate of the engine is reduced. Therefore, the EGR rate can be properly adjusted to match the working condition of the engine under different working conditions of the engine.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 illustrates a circuit diagram of an engine provided in accordance with an embodiment of the present invention;

FIG. 2 illustrates a cross-sectional view of an exhaust gas injection apparatus of an engine according to an embodiment of the present invention;

FIG. 3 illustrates a schematic diagram of a bleed tube of an engine provided in accordance with an embodiment of the present invention;

fig. 4 shows a flowchart of a control method of an engine provided according to an embodiment of the present invention.

Wherein the figures include the following reference numerals:

10. a cylinder;

20. an air line; 21. a throttle valve;

30. an air inlet pipe; 31. an air intake pipe body; 32. a tail gas injection device; 321. an injection pipe; 3211. a contraction section; 3212. a throat section; 3213. a diffusion section; 3214. a tail gas injection passage; 3215. an air intake pipe section; 3216. an air outlet pipe section; 322. a firing rod; 3221. a body section; 3222. a conical section; 33. a drive motor;

40. an exhaust pipe;

50. an EGR line; 51. an EGR valve;

60. a detection member; 61. a pressure sensor; 62. a temperature sensor;

70. a control member;

a1, diffusion angle of the diffusion section; a2, cone angle of the conical section.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to fig. 3, an embodiment of the present invention provides an engine, which includes a cylinder block, an air conduit 20, an air inlet pipe 30, an exhaust pipe 40, an EGR conduit 50, and a control element 70, wherein the cylinder block has an air cylinder 10, the air conduit 20 is provided with a throttle valve 21, the air inlet pipe 30 includes an air inlet pipe body 31 and a tail gas injection device 32, an air outlet of the air conduit 20 is communicated with an air inlet of the tail gas injection device 32, an air outlet of the tail gas injection device 32 is communicated with an air inlet of the air inlet pipe body 31, an air outlet of the air inlet pipe body 31 is communicated with an air inlet of the air cylinder 10, the tail gas injection device 32 includes an injection pipe 321 and an injection rod 322, the injection pipe 321 includes a contraction section 3211, a throat section 3212, and a pressure expansion section 3213, which are sequentially connected, in a direction in which the contraction section 3211 points to the pressure expansion section 3213, a cross-sectional dimension of the contraction section 3211 is gradually reduced, a cross-sectional dimension of the pressure expansion section 3213 is gradually increased, the side wall of the injection pipe 321 is provided with a tail gas injection passage 3214 communicated with the inner hole of the throat section 3212, the gas outlet of the cylinder 10 is communicated with the gas inlet of the exhaust pipe 40, the gas outlet of the exhaust pipe 40 is communicated with the gas inlet of the EGR pipeline 50, the gas outlet of the EGR pipeline 50 is communicated with the tail gas injection passage 3214, the EGR pipeline 50 is provided with an EGR valve 51, the tail gas injection device 32 further comprises a detection piece 60 for detecting the gas state of the injection pipe 321, the control piece 70 is electrically connected with the detection piece 60, wherein the injection rod 322 comprises a body section 3221 and a conical section 3222 which are connected with each other, the body section 3221 movably penetrates through the contraction section 3211, the conical section 3222 movably penetrates through the throat section 3212, and the cross-sectional size of the conical section 3222 is gradually reduced in the direction of the contraction section 3211 pointing to the pressure expansion section 3213.

By applying the technical scheme of the invention, when the engine works, air enters the air inlet of the tail gas injection device 32 from the air pipeline 20, and enters the air inlet pipe body 31 and the cylinder 10 of the cylinder body from the air outlet of the tail gas injection device 32. The tail gas enters the exhaust pipe 40 from the cylinder 10, enters the EGR pipeline 50 from the exhaust pipe 40, enters the tail gas injection passage 3214 of the tail gas injection device 32 from the EGR pipeline 50, and enters the throat section 3212 from the tail gas injection passage 3214, because the conical section 3222 of the injection rod 322 of the tail gas injection device 32 movably penetrates through the throat section 3212, in the direction of the contraction section 3211 pointing to the diffusion section 3213, the cross-sectional size of the conical section 3222 gradually decreases, and in the moving process of the conical section 3222, the cross-sectional area between the conical section 3222 and the throat section 3212 can be increased or decreased. When the engine is in a large-load working condition, the control element 70 can send out a control signal, the control signal is transmitted to the driving motor 33, the driving motor 33 drives the injection rod 322, so that the conical section 3222 moves towards the direction close to the diffusion section 3213, the cross-sectional area between the conical section 3222 and the throat section 3212 is reduced, the pressure of gas in the throat section 3212 is reduced, and the driving pressure difference of the tail gas is increased, so that the EGR rate of the engine is improved. Therefore, the EGR rate can be properly adjusted to match the working condition of the engine under different working conditions of the engine.

And when the guide rod 322 of the exhaust gas injection device 32 is located at the limit position and the sectional area of the flow cavity between the conical section 3222 and the throat section 3212 cannot be further adjusted, the opening degree of the throttle valve 21 or the EGR valve 51 can be controlled by the control part 70, so that the EGR rate is adjusted.

The ejector rod 322 moves along the axis of the throat section 3212, the limit position of the ejector rod 322 at the left end of the throat section 3212 is that the conical vertex of the conical section 3222 is located in the throat section 3212, and the limit position of the ejector rod 322 at the right end of the throat section 3212 is that the conical bottom of the conical section 3222 is located in the throat section 3212.

In the present embodiment, control member 70 is an electronic control unit of the engine.

It should be noted that the exhaust gas injecting device 32 has a plurality of exhaust gas injecting passages 3214, the plurality of exhaust gas injecting passages 3214 are disposed on the side wall of the contraction section 3211 and extend along the length direction of the contraction section 3211, and the plurality of exhaust gas injecting passages 3214 are disposed at intervals along the circumference of the contraction section 3211. The tail gas of adopting above-mentioned structure draws penetrates passageway 3214, can reduce the contained angle of the air current direction and the air flow direction that the export was jetted in drawing from the tail gas, and then can reduce the energy loss of air current to make the air stronger to the inhalability of waste gas, and then promote the ability of drawing to tail gas.

Furthermore, an EGR cooler is provided on the EGR line 50, and the EGR cooler can cool the exhaust gas, thereby protecting the EGR valve 51.

In this embodiment, the engine further includes a tail gas pipeline, an air outlet of the exhaust pipe 40 is communicated with an air inlet of the tail gas pipeline, a turbine is arranged on the tail gas pipeline, an air inlet of the air inlet pipe segment 3215 of the air inlet pipe 30 is communicated with an air outlet of the air pipeline 20, an intercooler is further arranged on the air pipeline 20, one end of the air pipeline 20 is connected with a compressor, and the turbine is in driving connection with the compressor. The engine adopting the structure can utilize the turbine to drive the compressor to work, thereby compressing air.

As shown in fig. 1, the exhaust gas injecting device 32 further includes a driving motor 33, a motor shaft of the driving motor 33 is drivingly connected to an end of the body section 3221 far away from the conical section 3222, and the throttle valve 21, the EGR valve 51 and the driving motor 33 are electrically connected to the control member 70. The driving motor 33 can be used for controlling the movement of the injection rod 322 in the injection pipe 321, so as to adjust the position of the conical section 3222 in the throat section 3212, and thus adjust the change of the sectional area of the circulation cavity formed between the conical section 3222 and the throat section 3212.

Specifically, the driving motor 33 employs a linear motor, by which the linear motion of the injection rod 322 can be driven.

As shown in fig. 1, the detecting element 60 includes a pressure sensor 61 and a temperature sensor 62, the injecting pipe 321 further includes an air inlet pipe segment 3215 connected to the contracting segment 3211, in a direction in which the contracting segment 3211 points to the pressure expanding segment 3213, the cross-sectional dimension of the air inlet pipe segment 3215 is unchanged, and both the pressure sensor 61 and the temperature sensor 62 are disposed in the air inlet pipe segment 3215. The pressure sensor 61 and the temperature sensor 62 can be used for collecting the air inlet state of air, and further the minimum sectional area of a circulation cavity formed between the conical section 3222 and the throat section 3212 can be calculated by combining the air flow.

In this embodiment, the gas inlet pipe segment 3215 includes an inner pipe segment and an outer pipe segment sleeved outside the inner pipe segment, an annular circulation cavity is provided between the outer side wall of the inner pipe segment and the inner side wall of the outer pipe segment, the plurality of tail gas injection passages 3214 are all communicated with the annular circulation cavity, and the outer pipe segment is provided with a tail gas inlet communicated with the annular circulation cavity. The gas inlet pipe segment 3215 with the above structure is convenient for setting an annular circulation cavity by using the gas inlet pipe segment 3215, so that the tail gas can enter the injection pipe 321 without setting redundant components, and the side wall of the contraction segment 3211 can be used for setting a tail gas injection passage 3214.

One end of the inner pipe section is connected with one end of the outer pipe section by a vertical plate so as to seal one end of the annular circulation cavity, and the other end of the inner pipe section is connected with the end face of the throat section 3212 so as to seal the other end of the annular circulation cavity.

It should be noted that the detection member 60 further includes a first flow meter and a second flow meter, the first flow meter is disposed on the EGR line 50, and the second flow meter is disposed on the air line 20. The first flowmeter and the second flowmeter can be used for collecting the flow of air and tail gas, and further calculating the actual EGR rate.

Wherein the first and second flow meters are not shown in the figure.

As shown in fig. 2, the diffusion angle a1 of the diffusion section is equal to the taper angle a2 of the conical section, and the exhaust gas injection device 32 with the above structure can make the angle of the flow cavity defined by the inner wall of the diffusion section 3213 and the outer wall of the conical section 3222 consistent, and does not generate size mutation, so that gas does not generate vortex in the flowing process, and the flow field is more stable while the gas flow resistance is reduced.

It should be noted that the diffuser angle a1 of the diffuser section refers to the angle between the corresponding sidewalls of the diffuser section 3213.

Specifically, the diffuser section has a diffuser angle a1 between 7 ° and 15 °. By adopting the angle range, the pressure recovery of the gas in the diffusion section 3213 can be facilitated, so that the gas cannot generate large pressure loss, and the flowing performance of the gas is more stable. If the diffusion angle a1 of the diffusion section is less than 7 °, it is not favorable for the pressure recovery of the gas in the diffusion section 3213, and the gas generates a large pressure loss, and if the diffusion angle a1 of the diffusion section is greater than 15 °, the gas may flash in the diffusion section 3213, thereby changing the flow characteristics of the gas.

In the present embodiment, the diffuser angle a1 of the diffuser section may be any value between 7 °, 8 °, 9 °, 10 °, 11 °, 12 °, 13 °, 14 °, 15 °, and 7 ° to 15 °.

As shown in FIG. 2, the cross-sectional dimension of the throat section 3212 is constant in the direction in which the converging section 3211 points toward the diverging section 3213, which facilitates the variation in the cross-sectional area of the flow lumen formed between the conical section 3222 and the throat section 3212.

As shown in fig. 2, the injection pipe 321 further includes an air outlet pipe segment 3216, the air outlet pipe segment 3216 is connected to an end of the pressure expanding segment 3213 far from the throat segment 3212, and the cross-sectional dimension of the air outlet pipe segment 3216 is unchanged in a direction in which the contracting segment 3211 points to the pressure expanding segment 3213. The gas outlet pipe segment 3216 can guide the gas flow, so that the gas flow is facilitated.

As shown in fig. 4, still another embodiment of the present invention provides a control method of an engine for controlling the operation of the engine provided above, the control method of the engine including:

s100, setting the throttle valve 21 and the EGR valve 51 at preset opening degrees;

s300, acquiring a required EGR rate and an actual EGR rate;

s400, comparing the required EGR rate with the actual EGR rate, and if the actual EGR rate does not meet the requirement, adjusting the opening degree of the throttle valve 21, the opening degree of the EGR valve 51 or the opening degree of the throat opening section 3212 to enable the actual EGR rate to meet the requirement.

The control method of the engine is applied, firstly, the throttle valve 21 and the EGR valve 51 are set at preset opening degrees, so that enough air flow passes through the air pipeline 20, enough tail gas flow passes through the EGR pipeline 50, the required EGR rate corresponding to the engine working condition is inquired according to a test calibration chart, the actual EGR rate is calculated according to the tail gas flow read by the first flowmeter and the air flow read by the second flowmeter, the required EGR rate is compared with the actual EGR rate, and the opening degree of the throttle valve 21 or the opening degree of the EGR valve 51 or the opening degree of the throat opening section 3212 is adjusted according to the comparison condition, so that the actual EGR rate meets the requirement. So that the EGR rate of the engine can be accurately controlled.

In this embodiment, the operating mode of the diesel engine can be locked by the rotating speed and the fuel injection quantity, and the operating mode of the gas engine can be locked by the rotating speed and the intake pressure.

In step S100, the throttle valve 21 and the EGR valve 51 are set at the preset opening degrees, which are the opening degrees of the throttle valve 21 and the EGR valve 51 adjusted to be relatively large, so that the EGR rate can be adjusted by adjusting the opening degree of the throat section 3212 to the maximum extent possible under the condition that the sufficient flow rate of the exhaust gas is passed through the air pipe 20, the sufficient flow rate of the exhaust gas is passed through the EGR pipe 50, and the opening degree of the throat section 3212 satisfies the adjustment condition, and the EGR rate is adjusted by decreasing the opening degree of the throttle valve 21 or the EGR valve 51 only under the condition that the opening degree of the throat section 3212 does not satisfy the adjustment condition.

Specifically, in step S300, a map of the required air flow and the required EGR rate of the engine under different operating conditions can be obtained through experiments, and the EGR rate of the engine under the operating conditions can be obtained through querying the map.

In step S400, adjusting the opening degree of the throat section 3212 means adjusting the cross-sectional area of the flow cavity between the throat section 3212 and the conical section 3222.

In the embodiment, the control method of the engine can reasonably utilize the Bernoulli principle, fully considers the EGR rate requirements of each operating point of the engine, and keeps the oil consumption and emission of each point to be optimal.

Specifically, in step S400, comparing the actual EGR rate with the required EGR rate, and if the actual EGR rate does not satisfy the requirement, the step of adjusting the opening degree of the throttle valve 21 or the opening degree of the EGR valve 51 or the opening degree of the throat section 3212 so that the actual EGR rate satisfies the requirement specifically includes:

in step S410, when the actual EGR rate is smaller than the required EGR rate, if the opening degree of the throat section 3212 does not reach the minimum position, the opening degree of the throat section 3212 is decreased so that the actual EGR rate satisfies the required EGR rate, and if the opening degree of the throat section 3212 reaches the minimum position, the opening degree of the throttle valve 21 is decreased so that the actual EGR rate satisfies the required EGR rate.

Step S420, when the actual EGR rate is larger than the required EGR rate, if the opening degree of the throat section 3212 does not reach the maximum position, the opening degree of the throat section 3212 is increased so that the actual EGR rate satisfies the required EGR rate, and if the opening degree of the throat section 3212 reaches the maximum position, the opening degree of the EGR valve 51 is decreased so that the actual EGR rate satisfies the required EGR rate.

It should be noted that, by reducing the opening degree of the throat section 3212, the opening degree of the EGR valve 51 can be prevented from being adjusted, the flow loss of the air flow in the injection pipe 321 is small, and the throttling loss caused by adjusting the EGR valve 51 is avoided, so that the ventilation efficiency of the engine is reduced, and further, the economy of the engine is reduced.

Specifically, a control signal can be sent out through the control element 70, the control signal is transmitted to the driving motor 33, the driving motor 33 drives the injection rod 322, so that the conical section 3222 moves towards the direction close to the diffuser section 3213, the cross-sectional area between the conical section 3222 and the throat section 3212 is reduced, the pressure of gas in the throat section 3212 is further reduced, the driving pressure difference of tail gas is increased, and the EGR rate of the engine is improved.

In the present embodiment, in step S410, when the opening degree of the throat section 3212 reaches the minimum position, the opening degree of the throttle valve 21 is decreased so that the actual EGR rate satisfies the demand. Since the cross-sectional area of the flow cavity between the throat section 3212 and the conical section 3222 has reached a minimum value, the flow rate of air can be reduced by reducing the opening of the throttle valve 21, and the EGR rate can be increased, thereby meeting the actual demand.

It should be noted that, by increasing the opening degree of the throat section 3212, the opening degree of the throttle valve 21 can be prevented from being adjusted, so that the flow loss of the airflow in the injection pipe 321 is low, and the throttle loss caused by adjusting the throttle valve 21 is avoided, thereby reducing the ventilation efficiency of the engine and further reducing the economy of the engine.

Specifically, the control element 70 may send a control signal, and the control signal is transmitted to the driving motor 33, and the driving motor 33 drives the injection rod 322, so that the conical section 3222 moves toward the direction close to the contraction section 3211, and the cross-sectional area between the conical section 3222 and the throat section 3212 is increased, thereby increasing the pressure of the gas in the throat section 3212, and reducing the driving pressure difference of the exhaust gas, thereby reducing the EGR rate of the engine.

In the present embodiment, in step S420, if the opening degree of the throat section 3212 reaches the maximum position, the opening degree of the EGR valve 51 is decreased so that the actual EGR rate satisfies the demand. Since the cross-sectional area of the flow cavity between the throat section 3212 and the conical section 3222 has reached a maximum value, the flow rate of air can be reduced by reducing the opening degree of the EGR valve 51, and thus the EGR rate can be reduced, so as to meet the actual requirement.

Note that, prior to the step of comparing the required EGR rate with the actual EGR rate, the control method of the engine further includes: s200, acquiring the minimum opening degree of the throat section 3212 according to the running condition of the engine and the gas state detected by the detecting element 60 of the engine. By obtaining the minimum opening degree of the throat section 3212 and making the opening degree of the throat section 3212 larger than the minimum opening degree of the throat section 3212, the engine can be prevented from being damaged due to unreasonable operation conditions.

In this embodiment, according to the operating condition of the engine, the lookup table may obtain the air flow rate required by the engine under the corresponding operating condition, and according to the required air flow rate and the air intake state, the air intake state may be collected by the pressure sensor 61 and the temperature sensor 62 arranged in the air intake pipe segment 3215, and the minimum cross-sectional area of the circulation cavity formed between the conical segment 3222 and the throat segment 3212 is calculated.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of not making a reverse description, these orientation words do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be considered as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An engine, characterized in that the engine comprises:

a cylinder block having a cylinder (10);

an air line (20) provided with a throttle valve (21);

the air inlet pipe (30) comprises an air inlet pipe body (31) and a tail gas injection device (32), an air outlet of the air pipeline (20) is communicated with an air inlet of the tail gas injection device (32), an air outlet of the tail gas injection device (32) is communicated with an air inlet of the air inlet pipe body (31), an air outlet of the air inlet pipe body (31) is communicated with an air inlet of the air cylinder (10), the tail gas injection device (32) comprises an injection pipe (321) and an injection rod (322), the injection pipe (321) comprises a contraction section (3211), a throat section (3212) and a pressure expansion section (3213) which are sequentially connected, the cross section size of the contraction section (3211) is gradually reduced in the direction of the contraction section (3213), the cross section size of the pressure expansion section (3213) is gradually increased, and a tail gas injection passage (3214) communicated with an inner hole of the throat section (3212) is arranged on the side wall of the injection pipe (321);

the air outlet of the cylinder (10) is communicated with the air inlet of the exhaust pipe (40);

an air outlet of the exhaust pipe (40) is communicated with an air inlet of the EGR pipeline (50), an air outlet of the EGR pipeline (50) is communicated with the tail gas injection channel (3214), and an EGR valve (51) is arranged on the EGR pipeline (50);

the control part (70), the tail gas injection device (32) also comprises a detection part (60) for detecting the gas state of the injection pipe (321), and the control part (70) is electrically connected with the detection part (60);

wherein the injection rod (322) comprises a body section (3221) and a conical section (3222) which are connected with each other, the body section (3221) is movably arranged through the contraction section (3211), the conical section (3222) is movably arranged through the throat section (3212), and the cross-sectional dimension of the conical section (3222) is gradually reduced in a direction of the contraction section (3211) to the expansion section (3213).

2. The engine according to claim 1, characterized in that the exhaust gas injection device (32) further comprises a driving motor (33), a motor shaft of the driving motor (33) is in driving connection with one end of the body section (3221) far away from the conical section (3222), and the throttle valve (21), the EGR valve (51) and the driving motor (33) are all electrically connected with the control member (70).

3. The engine according to claim 1, characterized in that the detecting element (60) comprises a pressure sensor (61) and a temperature sensor (62), the ejector pipe (321) further comprises an air inlet pipe section (3215) connected to the contracting section (3211), the cross-sectional dimension of the air inlet pipe section (3215) is constant in a direction in which the contracting section (3211) points to the diffuser section (3213), and both the pressure sensor (61) and the temperature sensor (62) are disposed in the air inlet pipe section (3215).

4. The engine according to claim 1, characterized in that the detection member (60) further includes a first flow meter provided on the EGR line (50) and a second flow meter provided on the air line (20).

5. The engine of claim 1,

the diffusion angle of the diffusion section is equal to the cone angle of the conical section; and/or the presence of a gas in the gas,

the diffusion angle of the diffusion section is between 7 and 15 degrees.

6. The engine of claim 1, characterized in that the throat section (3212) has a constant cross-sectional dimension in a direction in which the converging section (3211) points toward the diverging section (3213).

7. The engine of claim 1, characterized in that the ejector pipe (321) further comprises an outlet pipe segment (3216), the outlet pipe segment (3216) is connected to an end of the diffuser segment (3213) remote from the throat segment (3212), and the cross-sectional dimension of the outlet pipe segment (3216) is constant in a direction in which the contraction segment (3211) points toward the diffuser segment (3213).

8. A control method of an engine for controlling an operation of the engine according to any one of claims 1 to 7, the control method of an engine comprising:

setting a throttle valve (21) and an EGR valve (51) at preset opening degrees;

acquiring a required EGR rate and an actual EGR rate;

the required EGR rate is compared with the actual EGR rate, and if the actual EGR rate does not meet the requirement, the actual EGR rate meets the requirement by adjusting the opening degree of the throttle valve (21) or the opening degree of the EGR valve (51) or the opening degree of the throat section (3212).

9. The engine control method according to claim 8, characterized in that the step of comparing the actual EGR rate with the required EGR rate and, if the actual EGR rate does not meet the requirement, making the actual EGR rate meet the requirement by adjusting the opening degree of the throttle valve (21) or the opening degree of the EGR valve (51) or the opening degree of the throat section (3212) specifically comprises:

in the case that the actual EGR rate is smaller than the required EGR rate, if the opening degree of the throat section (3212) does not reach the minimum position, the opening degree of the throat section (3212) is decreased so that the actual EGR rate meets the requirement, and if the opening degree of the throat section (3212) reaches the minimum position, the opening degree of the throttle valve (21) is decreased so that the actual EGR rate meets the requirement;

under the condition that the actual EGR rate is larger than the required EGR rate, if the opening degree of the throat section (3212) does not reach the maximum position, the opening degree of the throat section (3212) is increased to make the actual EGR rate meet the requirement, and if the opening degree of the throat section (3212) reaches the maximum position, the opening degree of the EGR valve (51) is decreased to make the actual EGR rate meet the requirement.

10. The control method of an engine according to claim 8, characterized in that, before the step of comparing the required EGR rate with the actual EGR rate, the control method of an engine further comprises:

and acquiring the minimum opening degree of the throat section (3212) according to the running condition of the engine and the gas state detected by a detector (60) of the engine.