JP2020045874A - Exhaust device - Google Patents

Abstract

To efficiently restrain particulate matter such as soot from adhering onto a sensor in an exhaust pipe.SOLUTION: An exhaust device includes an exhaust pipe 20 which is connected to an engine and through which exhaust gas discharged from the engine flows, an A/F sensor 222 provided in the exhaust pipe 20, a throttle mechanism 210 which is provided on the upstream side of the A/F sensor 222 in the exhaust pipe 20 and reduces a diameter of a flow passage of the exhaust pipe 20, a determination section for determining a response delay of the A/F sensor 222 on the basis of a detection value of the A/F sensor 222, and a driving control section for controlling the throttle mechanism 210 so as to reduce the diameter of the flow passage of the exhaust pipe 20 when the response delay of the A/F sensor 222 is determined by the determination section.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an exhaust device.

  The exhaust gas discharged from the engine contains particulate matter such as hydrocarbons, carbon monoxide, nitrogen oxides, and soot. If these particulate matter adheres to a sensor provided in the exhaust pipe, the performance of the sensor may be affected. Patent Literature 1 discloses a technique in which a rectifying plate for rectifying exhaust gas is provided on an upstream side of a sensor inside an exhaust pipe so that a part of the exhaust gas is obliquely applied to the sensor.

JP 2007-321593 A

  However, in Patent Literature 1, there is a problem that the flow of exhaust gas in the exhaust pipe is always restricted by the current plate, and the accumulation of particulate matter on the sensor cannot be efficiently suppressed.

  Therefore, an object of the present invention is to provide an exhaust device that can efficiently suppress deposition of particulate matter such as soot on a sensor in an exhaust pipe.

  In order to solve the above problems, an exhaust device of the present invention is connected to an engine, an exhaust pipe through which exhaust gas discharged from the engine flows, a sensor provided in the exhaust pipe, and a sensor upstream of the sensor in the exhaust pipe. Provided on the side, a throttle mechanism that reduces the diameter of the flow path of the exhaust pipe, a determination unit that determines the response delay of the sensor based on the detection value of the sensor, and when the response delay of the sensor is determined by the determination unit, A drive control unit that controls the throttle mechanism so as to reduce the diameter of the flow path of the exhaust pipe.

  Further, the determination unit may determine the threshold value with reference to the engine speed and the engine load, and compare the value derived based on the detection value of the sensor with the threshold value to determine the response delay of the sensor.

  Further, in order to solve the above problem, an exhaust device of the present invention includes an exhaust pipe connected to an engine, through which exhaust gas discharged from the engine flows, a sensor provided in the exhaust pipe, and a sensor in the exhaust pipe. A throttle mechanism that is also provided on the upstream side and reduces the diameter of the flow path of the exhaust pipe, and a drive control unit that controls the throttle mechanism so as to reduce the diameter of the flow path of the exhaust pipe for a predetermined time from the start of the engine. , Is provided.

  The throttle mechanism may be arranged so that the wind direction of the exhaust gas is directed to the sensor when the diameter of the flow path of the exhaust pipe is reduced.

  Further, the sensor may be an A / F sensor.

  Further, the drive control unit may refer to the engine speed and the engine load, and control the throttle mechanism so as to cancel the diameter reduction of the flow path of the exhaust pipe when a preset canceling condition is satisfied.

  According to the present invention, it is possible to efficiently suppress the accumulation of particulate matter such as soot on the sensor in the exhaust pipe.

1 is a schematic view of an engine provided with an exhaust device. It is a schematic diagram of a diaphragm mechanism. It is a schematic diagram for explaining a response delay of an A / F sensor. 9 is a flowchart illustrating a flow of control processing of the aperture mechanism.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values and the like shown in the embodiments are merely examples for facilitating the understanding of the present invention, and do not limit the present invention unless otherwise specified. In the specification and the drawings, elements having substantially the same function and configuration will be denoted by the same reference numerals, and redundant description will be omitted. Elements not directly related to the present invention will be omitted. I do.

  FIG. 1 is a schematic diagram of an engine 102 provided with an exhaust device 200. As shown in FIG. 1, the engine 102 is, for example, a horizontally opposed four-cylinder engine. In the engine 102, two cylinder blocks 3 are arranged with the crankshaft 2 interposed therebetween. The cylinder block 3 is provided with two cylinder bores 3a, and the cylinder bores 3a of each cylinder block 3 face each other. Here, a horizontally opposed four-cylinder engine is exemplified, but the type of the engine 102 does not matter. In FIG. 1, the flow of the signal is indicated by a broken arrow.

  A crankcase 4 is formed integrally with the cylinder block 3. A cylinder head 5 is fixed to a side of the cylinder block 3 opposite to the crankcase 4. The crankshaft 2 is rotatably supported in the crank chamber 6. The crankcase 6 is formed by the crankcase 4.

  A piston 8 is connected to the crankshaft 2 via a connecting rod 7. The piston 8 is slidably accommodated in the cylinder bore 3a. The combustion chamber 9 is a space surrounded by the cylinder bore 3a, the cylinder head 5, and the crown of the piston 8.

  An intake port 10 and an exhaust port 11 are formed in the cylinder head 5 so as to communicate with the combustion chamber 9. Between the intake port 10 and the combustion chamber 9, the tip (umbrella) of the intake valve 12 is located. The tip (umbrella) of the exhaust valve 13 is located between the exhaust port 11 and the combustion chamber 9.

  A space surrounded by the cylinder head 5 and the head cover 14 is a cam chamber. An intake valve cam 15 and an exhaust valve cam 16 are provided in the cam chamber. The intake valve cam 15 contacts the other end of the intake valve 12. The rotation of the intake valve cam 15 causes the intake valve 12 to move in the axial direction. Thereby, the intake valve 12 opens and closes between the intake port 10 and the combustion chamber 9. The exhaust valve cam 16 contacts the other end of the exhaust valve 13. As the exhaust valve 13 rotates, the exhaust valve 13 moves in the axial direction. Thereby, the exhaust valve 13 opens and closes between the exhaust port 11 and the combustion chamber 9.

  An intake manifold 17 is provided upstream of the intake port 10. Intake manifold 17 communicates with intake port 10. The intake manifold 17 forms a part of an intake pipe 18 through which intake air flows. The intake pipe 18 includes an intake manifold 17 and an intake pipe upstream portion 18a.

  The intake manifold 17 has a collecting part 21 and an intake pipe downstream part 22. The collecting part 21 communicates with the intake pipe upstream part 18a. The collecting portion 21 is a tank into which intake air flows from the intake pipe upstream portion 18a. The intake pipe downstream portion 22 branches from the collecting portion 21 and has a downstream end connected to the intake port 10.

  An air cleaner 23 and a throttle valve 24 are sequentially provided in the intake pipe upstream portion 18a from the upstream side. The air cleaner 23 removes foreign substances such as dust and dirt contained in the intake air. The throttle valve 24 varies the flow rate of intake air supplied to the intake manifold 17. The opening of the throttle valve 24 is adjusted by an actuator (not shown). The opening of the throttle valve 24 is determined with reference to a predetermined map set in advance. In this predetermined map, the opening degree of the throttle valve 24 with respect to the accelerator opening degree and the engine speed is set in advance.

  The ECU 201 includes a microcomputer including a central processing unit (CPU), a ROM storing programs and the like, a RAM serving as a work area, and the like, and controls the entire engine 102. The ECU 201 acquires the operating status (engine speed and engine load) of the engine 102 from the accelerator opening sensor 220 and the crank angle sensor 221. Further, the ECU 201 acquires information on the air-fuel ratio of the exhaust gas in the exhaust pipe 20 from the A / F sensor 222. Further, the ECU 201 functions as a drive control unit 203 that controls the actuator 211.

  The intake air whose flow rate is adjusted by the throttle valve 24 flows into the collecting portion 21 of the intake manifold 17. The intake air that has flowed into the collecting part 21 is distributed to the intake pipe downstream part 22 and guided to the combustion chamber 9 via the intake port 10. The air guided to the combustion chamber 9 mixes with fuel injected from an injector (not shown). The mixture of the intake air and the fuel is ignited by a spark plug (not shown) provided in the cylinder head 5.

  The combustion of the air-fuel mixture causes the piston 8 to reciprocate in the cylinder bore 3a. The power of the reciprocating motion of the piston 8 is converted into the power of the rotational motion of the crankshaft 2 through the connecting rod 7. The exhaust gas is led from the combustion chamber 9 to the exhaust device 200 via the exhaust port 11. The exhaust manifold 19 is provided downstream of the exhaust port 11. The exhaust manifold 19 communicates with the exhaust port 11. The exhaust manifold 19 forms a part of an exhaust pipe 20 through which exhaust gas flows.

  The exhaust device 200 includes an exhaust pipe 20, an ECU 201, a throttle mechanism 210, an accelerator opening sensor 220, a crank angle sensor 221, an A / F (Air By Fuel) sensor 222, and a catalyst 25. The exhaust gas is exhausted outside the vehicle after being purified by the catalyst 25.

  The aperture mechanism 210 is provided upstream of the A / F sensor 222. The aperture mechanism 210 includes an aperture section 210a (see FIG. 2) formed from a plurality of plate members, and an aperture substrate 210b (see FIG. 2) to which the aperture section 210a is fixed. The aperture mechanism 210 operates so that the aperture section 210 a is moved by the actuator 211 and the aperture section 210 a opens and closes the exhaust pipe 20. Hereinafter, the throttle unit 210a when the exhaust pipe 20 is closed is referred to as a closed state, and the throttle unit 210a when the exhaust pipe 20 is opened is referred to as a closed state.

  The A / F sensor 222 is provided in the exhaust pipe 20 upstream of the catalyst 25. The A / F sensor 222 detects the air-fuel ratio of the exhaust gas. A signal indicating the air-fuel ratio detected by the A / F sensor 222 is transmitted to the ECU 201. The ECU 201 derives the current air-fuel ratio based on the signal indicating the air-fuel ratio acquired from the A / F sensor 222.

  Further, the ECU 201 functions as an air-fuel ratio control unit 204 that controls the air-fuel ratio of the air-fuel mixture burned by the engine 102. The air-fuel ratio control unit 204 performs feedback control on the amount of fuel and the amount of air supplied to the combustion chamber of the engine 102 based on the current air-fuel ratio, for example, to be a stoichiometric air-fuel ratio.

  Further, the ECU 201 functions as the determination unit 202 that determines whether or not a signal indicating the air-fuel ratio acquired from the A / F sensor 222 has a response delay. The determining unit 202 determines whether a response delay has occurred in the A / F sensor 222 based on the accelerator opening derived by the ECU 201. When the determination unit 202 determines that a response delay has occurred in the A / F sensor 222, the drive control unit 203 operates the actuator 211 to perform the aperture control so as to close the aperture unit 210a. Similarly, at the time of starting the engine 102, the drive control unit 203 operates the actuator 211 so as to close the throttle unit 210a to execute the throttle control. However, during the execution of the aperture control, if the determination unit 202 determines that the predetermined release condition set in advance is satisfied, the drive control unit 203 causes the actuator 211 to open the aperture unit 210a. Is operated to end the aperture control.

  FIG. 2 is a schematic diagram of the aperture mechanism 210. In FIG. 2, the flow of the exhaust gas is indicated by solid arrows. FIGS. 2A and 2B are schematic diagrams illustrating a case where the drive control unit 203 operates the actuator 211 so as to open the aperture unit 210a. As shown in FIG. 2A, when the throttle unit 210a is controlled to be in the open state, the throttle unit 210a is largely open, and the upstream and downstream sides of the throttle mechanism 210 are configured to control the exhaust gas flow. No significant change in flow velocity occurs. Therefore, for example, when the flow rate of the exhaust gas flowing through the exhaust pipe 20 is low, the particulate matter 300 such as soot contained in the exhaust gas accumulates on the A / F sensor 222 as shown in FIG. There are cases. When the particulate matter 300 accumulates on the A / F sensor 222, a response delay of the A / F sensor 222 occurs due to the influence of the particulate matter 300 accumulated on the A / F sensor 222.

  FIG. 2C is a schematic diagram in the case where the drive control unit 203 operates the actuator 211 so as to close the aperture unit 210a. In the present embodiment, when a response delay equal to or greater than a preset threshold occurs in the A / F sensor 222 due to the influence of the particulate matter 300 deposited on the A / F sensor 222, the drive control unit 203 causes the throttle unit 210a to operate. The actuator 211 is operated so as to be in the closed state. As shown in FIG. 2C, when the throttle unit 210a is controlled to be in the closed state, the opening of the throttle unit 210a is small, so that the flow velocity of the exhaust gas downstream of the upstream side of the throttle mechanism 210 is higher. Become. The throttle mechanism 210 is arranged so that the wind direction of the exhaust gas is directed to the A / F sensor 222 when the throttle unit 210a is controlled to be in the closed state. As a result, as shown in FIG. 2C, the exhaust gas having the increased flow velocity collides with the A / F sensor 222, and can blow off the particulate matter 300 deposited on the A / F sensor 222.

  Immediately after the start of the engine 102, the amount of water contained in the exhaust gas is relatively large. If the water contained in the exhaust gas adheres to the surface of the A / F sensor 222 and the surface of the A / F sensor 222 is wet, the particulate matter 300 is deposited (adhered) on the A / F sensor 222. It becomes easy to do. Thus, in the present embodiment, the drive control unit 203 operates the actuator 211 so as to close the throttle unit 210a even during a period from the start of the engine 102 until a predetermined time elapses. Accordingly, even immediately after the start of the engine 102 having a relatively large amount of moisture contained in the exhaust gas, it is possible to suppress the moisture contained in the exhaust gas from adhering to the surface of the A / F sensor 222. . Therefore, it is possible to suppress the deposition of the particulate matter 300 on the A / F sensor 222.

  However, even when the throttle unit 210a is controlled to be in the closed state, the determination unit 202 determines that the operation state (engine speed and engine load) of the engine 102 satisfies a predetermined release condition set in advance. If it is determined, the drive control unit 203 operates the actuator 211 so as to open the throttle unit 210a. For example, a high release speed when the engine speed is equal to or higher than a predetermined value and a high load time when the engine load is equal to or higher than a predetermined value are set as the predetermined release conditions. At the time of high rotation and high load, the pressure in the exhaust pipe 20 is increasing. Therefore, by opening the throttle portion 210a, it is possible to prevent the engine 102 from being applied with unnecessary pressure. Becomes possible. Also, at high rotation speed and high load, even if the throttle portion 210a is open, the flow rate of the exhaust gas flowing through the exhaust pipe 20 is high. The risk of depositing 300 is low.

  FIG. 3 is a schematic diagram for explaining a response delay of the A / F sensor 222. FIG. 3A is a graph showing the relationship between the accelerator opening derived by the ECU 201 and the A / F value (air-fuel ratio) derived by the ECU 201. As for the A / F value in FIG. 3, the solid line shows the value at the time of normal operation, and the broken line shows the value at the time of response delay.

  The change in the A / F value occurs when the vehicle is accelerated or decelerated. FIG. 3 shows a change in the A / F value during acceleration. For example, in the case where the A / F sensor 222 is in a normal state in which no response delay occurs, the A / F value is changed to a predetermined value a (for example, the theoretical value) as shown in FIG. The time T1 until the convergence to the air-fuel ratio) is set in advance. Then, it is assumed that it takes time T2 when the A / F value converges to a predetermined value a in the A / F value actually derived by the ECU 201. The determining unit 202 determines that a response delay has occurred when the ratio of the time T3 to the time T1 is equal to or greater than the threshold, and generates a response delay when the ratio of the time T3 to the time T1 is less than the threshold. It is determined that it has not been done.

  At this time, the threshold value used for determining the response delay may be a fixed value, or the operating state of the engine 102 (engine speed and engine load) is associated with the threshold value used for determining the response delay. The threshold may be determined with reference to the map.

  Hereinafter, the flow of the control process of the throttle mechanism 210 by the ECU 201 will be described. FIG. 4 is a flowchart showing the flow of the control process of the aperture mechanism 210. The control process of the throttle mechanism 210 is executed when the engine 102 is driving.

  When the control process of the throttle mechanism 210 is started, the determination unit 202 determines whether or not the engine 102 has been started (S10). As a result, if the engine 102 is started (YES in step S10), the drive control unit 203 executes the throttle control for operating the actuator 211 so as to close the throttle unit 210a (S12). Thereafter, the determination unit 202 determines whether a predetermined time has elapsed since the start of the engine 102 (S14).

  If the predetermined time has not elapsed since the start of the engine 102 (NO in step S14), the determination unit 202 acquires the operating status (engine speed and engine load) of the engine 102 (step S16). The determining unit 202 determines whether or not the condition for canceling the throttle control is satisfied based on the operating condition (engine speed and engine load) of the engine 102 acquired in step S16 (step S18). The determination unit 202 performs the processing of steps S12 to S16 until a predetermined time has elapsed from the start of the engine 102 (YES in step S14) or until the condition for canceling the aperture control is satisfied (YES in step S18). The execution of the aperture control is repeated. When a predetermined time has elapsed from the start of the engine 102 (YES in step S14) and when the condition for canceling the throttle control is satisfied (YES in step S18), the drive control unit 203 opens the throttle unit 210a. Thus, the actuator 211 is operated (the aperture control ends: S20), and the control process of the aperture mechanism 210 ends.

  On the other hand, if the engine 102 is not started (NO in step S10), the ECU 201 acquires the operating state of the engine 102 (engine speed and engine load) and the detection value of the A / F sensor 222 (step S22). The determination unit 202 determines that the response delay of the A / F sensor 222 is equal to or greater than the threshold value based on the operation state (engine speed and engine load) of the engine 102 and the detection value of the A / F sensor 222 acquired in step S22. It is determined whether or not (step S24). As a result, if the response delay of the A / F sensor 222 is equal to or greater than the threshold (YES in step S24), the drive control unit 203 operates the actuator 211 to close the aperture unit 210a (performs aperture control). Yes: S26). The ECU 201 determines whether or not the condition for canceling the throttle control is satisfied based on the operating state (engine speed and engine load) of the engine 102 acquired in step S22 (step S28). Thereafter, the ECU 201 proceeds to steps S22 to S28 until the response delay of the A / F sensor 222 becomes less than the threshold (NO in step S24) or until the condition for canceling the aperture control is satisfied (YES in step S28). Is repeated, and the execution of the aperture control is continued. When the response delay of the A / F sensor 222 is less than the threshold value (NO in step S24) and when the condition for canceling the aperture control is satisfied (YES in step S28), the drive control unit 203 controls the aperture unit 210a. The actuator 211 is operated so as to be in the open state (the aperture control ends: S20), and the control process of the aperture mechanism 210 returns.

  As described above, in the present embodiment, by restricting the driving of the throttle mechanism 210, it is possible to efficiently suppress the attachment of particulate matter such as soot to the A / F sensor 222 in the exhaust pipe 20. Can be.

  As described above, the preferred embodiments of the present invention have been described with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such embodiments. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. Is done.

For example, in the above embodiment, the case where the A / F sensor 222 is provided in the exhaust pipe 20 has been described, but the sensor provided in the exhaust pipe 20 is not particularly limited. For example, O ₂ sensor disposed in the exhaust pipe 20, a pressure sensor, the present invention may be applied with respect to the NOx sensor and the like.

  The present invention can be used for an exhaust device.

102 Engine 20 Exhaust pipe 202 Judgment section 210 Throttle mechanism 222 A / F sensor

Claims (6)

An exhaust pipe connected to the engine and through which exhaust gas discharged from the engine flows;
A sensor provided in the exhaust pipe,
A throttle mechanism provided upstream of the sensor in the exhaust pipe to reduce the diameter of the flow path of the exhaust pipe;
A determining unit that determines a response delay of the sensor based on a detection value of the sensor;
When a response delay of the sensor is determined by the determination unit, a drive control unit that controls the throttle mechanism to reduce the diameter of the flow path of the exhaust pipe;
An exhaust device comprising:   The determination unit determines a threshold value by referring to an engine speed and an engine load, and determines a response delay of the sensor by comparing a value derived based on a detection value of the sensor with the threshold value. Item 7. The exhaust device according to Item 1. An exhaust pipe connected to the engine and through which exhaust gas discharged from the engine flows;
A sensor provided in the exhaust pipe,
A throttle mechanism provided upstream of the sensor in the exhaust pipe to reduce the diameter of the flow path of the exhaust pipe;
A drive control unit that controls the throttle mechanism so as to reduce the diameter of the flow path of the exhaust pipe for a predetermined time from the start of the engine.
An exhaust device comprising:   4. The exhaust device according to claim 1, wherein the throttle mechanism is arranged such that a wind direction of the exhaust gas is directed to a sensor when a diameter of the flow path of the exhaust pipe is reduced. 5.   The exhaust device according to any one of claims 1 to 4, wherein the sensor is an A / F sensor.   The drive control unit refers to an engine speed and an engine load, and controls the throttle mechanism so as to release the diameter reduction of the flow path of the exhaust pipe when a preset release condition is satisfied. Item 6. The exhaust device according to any one of Items 1 to 5.

Images