JP2018080585A - Method and device for determining deterioration in catalyst of exhaust system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for determining deterioration in a catalyst of an exhaust system that can exactly determine a deterioration state of a catalyst of an exhaust system by a simple configuration, and to provide a device.SOLUTION: A method for determining deterioration in a catalyst of an exhaust system determines a deterioration state of a catalyst using any of one of exhaust temperature, oxygen concentration upstream of the catalyst 23, engine rpm of an engine and a travel distance cumulative value of a vehicle to which the engine is mounted, in an engine exhaust system provided with an exhaust temperature sensor 25 and an oxygen concentration sensor 26 upstream of the catalyst 23 fitted to an intermediate part of a muffler 12.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method and an apparatus for determining a deterioration state of a catalyst mounted on an exhaust system in a vehicle such as a motorcycle.

Conventionally, in motorcycles and the like, a technology for determining the deterioration state of a catalyst by mounting oxygen concentration sensors (O ₂ sensors) on both the upstream side and the downstream side of the catalyst and measuring the oxygen concentration in the exhaust gas. Are known.

  Further, as disclosed in, for example, Patent Document 1, in a control device capable of determining deterioration of a catalyst for purifying exhaust gas discharged from an internal combustion engine, a catalyst temperature sensor for detecting the temperature of the catalyst, and a catalyst The exhaust gas temperature sensor that detects the temperature of the exhaust gas before flowing in, and the deterioration of the catalyst is determined based on the deviation between the catalyst temperature detected by the catalyst temperature sensor and the exhaust gas temperature detected by the exhaust gas temperature sensor Determination means.

JP2015-169131A

However, in the prior art, the O ₂ sensor is attached so as to be substantially orthogonal to the tubular portion of the muffler. As a result, the O ₂ sensor protrudes around the tubular part of the muffler, so that the shape and arrangement of the muffler and peripheral parts (for example, engine cases, floor panels, suspension parts, in the case of motorcycles, swing arms, tires, etc.) It is easy to give restrictions.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an exhaust system catalyst deterioration determination method and apparatus that can accurately determine the deterioration state of an exhaust system catalyst with a simple configuration.

  An exhaust system catalyst deterioration determination method according to the present invention is an engine exhaust system in which an exhaust temperature sensor and an oxygen concentration sensor are provided upstream of a catalyst mounted in an intermediate portion of a muffler. The deterioration state of the catalyst is determined using any one of a concentration, an engine speed of the engine, and a cumulative travel distance of a vehicle on which the engine is mounted.

  According to the present invention, it is possible to accurately determine the deterioration state of the catalyst in the exhaust system with a simple configuration.

1 is a side view showing an overall configuration of a motorcycle according to the present invention. It is a block diagram which shows the structural example of the catalyst deterioration determination apparatus which concerns on the Example of this invention. It is the perspective view which looked at the exhaust system periphery which concerns on the Example of this invention from the left side. It is a figure which shows the specific structural example of the exhaust system which concerns on the Example of this invention. It is a flowchart which shows the procedure of the catalyst degradation determination method in the Example of this invention.

Hereinafter, preferred embodiments of an exhaust system catalyst deterioration determination method and apparatus according to the present invention will be described with reference to the drawings.
An exhaust system catalyst deterioration determination method according to an embodiment of the present invention is an engine exhaust system in which an exhaust temperature sensor and an oxygen concentration sensor are provided on an upstream side of a catalyst attached to an intermediate portion of a muffler. The deterioration state of the catalyst is determined using any one of the exhaust gas temperature on the side, the oxygen concentration, the engine speed of the engine, and the cumulative travel distance of the vehicle on which the engine is mounted.

  In the catalyst deterioration determination method according to the present invention, it is possible to estimate the high temperature state of the catalyst using a plurality of parameters relating to the state of the exhaust gas, and to accurately know the deterioration state. Further, by providing the exhaust temperature sensor and the oxygen concentration sensor only on the upstream side of the catalyst, the catalyst deterioration determination device can be configured simply.

FIG. 1 is a diagram showing an overall configuration of a motorcycle 100 according to the present invention. First, a schematic configuration of the entire motorcycle 100 will be described with reference to FIG. In the drawings used in the following description, the direction in which a rider who rides on the motorcycle 100 looks at the front of the vehicle is defined as the front, and the opposite direction is defined as the rear. Also, the rider's right side is on the right and the left side is on the left, and these directions are indicated by arrows as needed.
In FIG. 1, a motorcycle 100 may be a scooter type vehicle, and two front parts supported by a steering head pipe so as to be turnable to the left and right are provided at the front part of a body frame made of steel or aluminum alloy. A fork 101 is provided. A handle 102 is fixed to the upper end of the front fork 101, and grips 103 are provided on the left and right ends of the handle 102. A front wheel 104 is rotatably supported on the lower portion of the front fork 101, and a front fender 105 is fixed so as to cover the upper portion of the front wheel 104.

  A swing arm 106 is swingably provided at the rear of the vehicle body frame, and a rear shock absorber is mounted between the vehicle body frame and the swing arm 106. The swing arm 106 incorporates a belt type continuously variable transmission or a power transmission mechanism including a plurality of gear trains. A rear wheel 107 is rotatably supported at the rear end of the swing arm 106, and the rear wheel 107 is rotationally driven via the power transmission mechanism described above. The rear fender 108 is fixed so as to cover the upper part of the rear wheel 107.

  Although not shown in detail, an air-fuel mixture is supplied to an engine unit 1 mounted on the vehicle body frame from an intake system including an air cleaner device and the like, and exhaust gas after combustion in an exhaust system, which will be described later, is discharged from an exhaust pipe. Exhausted through. Furthermore, the main components of the vehicle including the engine unit and the fuel tank, the radiator device, and the like are covered with a vehicle body cover, which will be described later, and the appearance of the vehicle is smoothly and clearly integrated as shown in FIG. Formed. In addition, a driver's seat 109 and a tandem seat 110 are continuously provided from substantially the center of the vehicle to the rear.

  With respect to the vehicle body cover at the front portion of the motorcycle 100, the front of the vehicle body is covered from the front by a front cowling 111, and a movable wind screen 112 is disposed above the front cowling 111. Further, a meter 113 is provided above the front cowling 111 and located behind the wind screen 112. The meter 113 has a built-in meter body portion in which instruments including a speedometer, a tachometer, or various indicators are unitized. The periphery of the meter 113 and its periphery are front side by a meter panel positioned immediately after the wind screen 112. Covered from.

  The leg shield 114 is disposed so as to be positioned below the front cowling 111 and in front of the occupant's legs. The leg shield 114 and the like are coupled to each other together with the front cowling 111 and the meter panel located behind the front cowling 111 to form a vehicle body cover and cover the front of the vehicle body to form an integral appearance. The vehicle body cover and the wind screen 112 described above are arranged and configured to cover the periphery of the handle 102 including at least the legs and upper body of the occupant from the front in the vehicle traveling direction.

  On the left and right sides near the lower portion of the leg shield 114, left and right footrest portions 115 having a low floor are provided to the rear, and an occupant can sit on the seat 109 with his / her feet on the footrest portion 115. A foot rest for the tandem seat 110 is provided behind the foot rest 115. A center cover 116 is provided between the left and right footrests 115 so as to extend forward and backward while protruding upward, and a floor tunnel portion is formed inside. On the vehicle side, the lower part is covered with a lower side cover 117 and the rear part is covered with a rear side cover 118. The lower side cover 117 and the rear side cover 118 constitute a vehicle body cover around the rear portion of the vehicle. Various vehicle body covers including the vehicle body cover around the vehicle front portion described above are basically formed of synthetic resin. It is attached and fixed directly to the frame or indirectly through a support member such as a bracket.

  Further, for example, a pair of left and right headlamps 119 is attached to the front center of the front cowling 111, and a pair of side mirrors 120 that are paired to the left and right are supported moderately behind and diagonally above each headlamp 119. The

  An air-fuel mixture is supplied from a fuel injection device to an engine unit 1 (shown by a dotted line in FIG. 1) mounted at a predetermined portion of a vehicle body frame, and exhaust gas after combustion in the engine is exhausted through an exhaust pipe. Is done. In this embodiment, the engine may be a four-cycle multi-cylinder engine, for example. Here, it is a block diagram which shows the structural example of the catalyst deterioration determination apparatus which concerns on a present Example. As shown in FIG. 2, the engine 1A of the engine unit 1 is provided with an in-vehicle engine control unit (ECU) 2, and a plurality of functional systems cooperate with auxiliary machines and the like under the control of the ECU 2. As a result, the engine unit 1 as a whole is smoothly operated.

  Next, FIG. 3 is a perspective view of the periphery of the exhaust system 10 according to the present embodiment as viewed from the left side, and FIG. 4 is a diagram illustrating a specific configuration example of the exhaust system 10. The exhaust system 10 includes an exhaust pipe 11 connected to the cylinder head of the engine 1A (FIG. 1, dotted line portion) and a muffler 12 connected to the downstream side of the exhaust pipe 11. The muffler 12 substantially functions as a silencer. The distal end portion of the exhaust pipe 11 is connected to an exhaust port of a cylinder head of the engine 1A through a flange 13.

  The muffler 12 has a double structure consisting of an outer cylinder 14 and an inner cylinder 15 that are concentric with each other, and a sound absorbing material 16 is loaded therebetween. A punching hole 17 is formed in the inner cylinder 15, and the inner cylinder 15 and the sound absorbing material 16 communicate with each other through the punching hole 17. The inside of the muffler 12 is divided into three spaces in the present example by baffles 18 and 19, and a front pipe 20, a center pipe 21 and a tail piece (pipe) 22 are held by these baffles 18 and 19. A catalyst 23 is attached to the downstream end of the exhaust gas flow in the front pipe 20. A tail end 24 is connected to the downstream end of the tail piece 22.

  In the exhaust system 10, exhaust gas discharged from the engine 1 </ b> A is introduced into the muffler 12 through the exhaust pipe 11, and finally discharged from the tail end 24 of the tail piece 22 to the outside. Specifically, as shown by the dotted arrows in FIG. 4, the exhaust gas introduced from the exhaust pipe 11 into the muffler 12 sequentially passes through the front pipe 20, the center pipe 21, and the tail piece, and is discharged from the tail end 24. At that time, the exhaust gas is purified by flowing through the catalyst 23 in the muffler 12, thereby purifying the exhaust gas.

As described above, in the exhaust system 10 of the engine 1A in which the catalyst 23 is mounted in the middle portion of the muffler 12, the exhaust temperature sensor and the oxygen concentration sensor (O ₂ sensor) are provided only on the upstream side of the catalyst 23. In the present embodiment, as shown in FIGS. 3 and 4, one exhaust temperature sensor 25 (downstream side) and one oxygen concentration sensor 26 (upstream side) are disposed in the middle of the exhaust pipe 11.
Based on the temperature of the exhaust gas detected by the exhaust temperature sensor 25 (simply referred to as exhaust temperature) and the oxygen concentration in the exhaust gas detected by the oxygen concentration sensor 26, the deterioration state of the catalyst 23 is determined as described later.

  Referring to FIG. 2, ECU 2 is accompanied by a catalyst deterioration determination unit 3 that determines the deterioration state of catalyst 23. The detection signals of the exhaust temperature sensor 25 and the oxygen concentration sensor 26 are sent to the catalyst deterioration determination unit 3, respectively. Further, the engine 1A is accompanied by an engine speed sensor 1B that detects the speed of the engine 1A. The detection signal of the engine speed sensor 1B is sent to the catalyst deterioration determination unit 3. The catalyst deterioration determination unit 3 determines the deterioration state of the catalyst 23 based on detection signals from each sensor or the like, and notifies the failure determination of the catalyst 23 by the catalyst deterioration state notification unit 4 using, for example, the meter 113 (see FIG. 1). It has become.

  Here, the exhaust temperature, the oxygen concentration, the engine speed, and the cumulative travel distance are included as parameters for determining the deterioration state of the catalyst 23 as a criterion for failure determination. First, in general, the function of a catalyst is remarkably impaired in an extremely high temperature state, but in this embodiment, the exhaust temperature in this state is set as a limit temperature (for example, 1000 ° C.), and the exhaust temperature exceeds the limit temperature even once. Performs failure determination.

Further, since the threshold value due to catalyst deterioration can be determined by the exhaust gas durability test, a failure determination is made when the travel distance of the vehicle reaches a predetermined value. In this embodiment, the travel distance data of the motorcycle 100 is sent to the catalyst deterioration determination unit 3, and a failure is determined based on the travel distance data. In this case, the predetermined value can be set according to the category of the vehicle, for example, a travel distance of 20000 km or 35000 km.
In cases other than the limit temperature, the failure determination is performed when any of a plurality of deterioration preliminary determinations among the plurality of determination parameters is made.

  Further, when the catalyst exceeds 900 ° C., its activity is remarkably lowered. Since the deterioration of the catalyst itself proceeds at a high temperature, it is necessary to keep the temperature at 900 ° C. or lower. In this embodiment, if the exhaust temperature continuously travels for a certain period of time (for example, 10 seconds or more) at a high temperature of a predetermined temperature (for example, 800 ° C.) or more, 1 count (1 time) is set, and the total number of such traveling states is 10,000 or more. If it is repeated, a preliminary deterioration judgment is performed.

  Further, the detection signal of the oxygen concentration sensor 26 is sent to the ECU 2, that is, the lean / rich of the oxygen concentration in the exhaust gas is determined by feedback of the detection signal of the oxygen concentration sensor 26. In the rich state, the amount of unburned gas in the exhaust gas is large, and when the fuel adheres to the heated catalyst, the unburned gas burns on the surface of the catalyst, and the temperature rises. The longer the rich state, the stronger the effect on the catalyst. Normally, control is performed so that the stoichiometric air-fuel ratio is obtained by feedback control of the oxygen concentration signal, but the rich state is brought about at the time of sudden acceleration or high rotation. In this embodiment, when the rich state is determined by the oxygen concentration sensor 26 (the amount of unburned gas in the exhaust gas is excessive), if the vehicle runs continuously for a certain period of time (for example, 3 minutes or more), the count is 1 (one time). When the total number of such running states is repeated 10,000 times or more, deterioration preliminary determination is performed.

  Further, if the engine speed is equal to or higher than a predetermined speed (for example, 80% of the maximum speed) and continuously travels for a certain period of time (for example, 3 minutes or more), 1 count (one time) is set. When the number of repetitions is repeated 10 times or more, deterioration preliminary determination is performed.

In the present invention, the deterioration preliminary determination of the catalyst 23 is performed based on the exhaust temperature, the oxygen concentration, the engine speed, and the cumulative travel distance, and the failure determination of the catalyst 23 is performed when any of the plurality of deterioration preliminary determinations is made.
In the present embodiment, when the exhaust temperature exceeds the limit temperature even once, a failure determination is performed immediately.
Further, the failure determination of the catalyst 23 is performed when the deterioration preliminary determination of the exhaust temperature, the oxygen concentration, the engine speed, and the mileage cumulative value is 3 or more.

Next, an exhaust system catalyst deterioration determination method according to the present invention will be described in detail.
When the engine 1A is started, exhaust gas discharged from the engine 1A is introduced into the muffler 12 through the exhaust pipe 11, and is discharged from the tail end 24 to the outside. At this time, detection signals detected by the exhaust temperature sensor 25, the oxygen concentration sensor 26, and the engine speed sensor 1B are sent to the ECU 2, and the catalyst deterioration determination unit 3 determines the deterioration state of the catalyst 23 based on these detection signals. To do.

  FIG. 5 is a flowchart showing the procedure of the catalyst deterioration determination method in this embodiment. In step S1, it is determined whether or not the exhaust temperature exceeds 1000 ° C., and if it exceeds 1000 ° C., that is, if it exceeds the limit temperature, a failure determination is performed.

  On the other hand, if the exhaust temperature is equal to or lower than the limit temperature, it is determined in step S2 whether or not the travel distance of the vehicle reaches a predetermined value (guaranteed catalyst distance). In this case, the first deterioration preliminary determination (1) is made. In the flowchart of FIG. 5, the total number of times of preliminary deterioration determination is also shown.

Next, in step S3, it is determined whether or not the time when the exhaust gas temperature exceeds a certain temperature reaches a predetermined time. If it exceeds the predetermined time, a preliminary deterioration determination is performed. In this case, the second deterioration preliminary determination (2) is made.
Next, in step S4, it is determined whether or not the accumulated time value of the exhaust gas rich state reaches a predetermined value, and if it exceeds the predetermined time, a deterioration preliminary determination is performed. In this case, a third deterioration preliminary determination (3) is made.
As described above, when the deterioration preliminary determination is performed three or more times in steps S2 to S4, the failure determination of the catalyst 23 is performed.

If the travel distance is within the guaranteed catalyst distance in step S2, it is determined in step S5 whether or not the time when the exhaust gas temperature exceeds a certain temperature reaches a predetermined time. I do. In this case, the first deterioration preliminary determination (1) is made.
Next, in step S6, it is determined whether or not the accumulated time value of the exhaust gas rich state reaches a predetermined value. If the predetermined time is exceeded, preliminary deterioration determination is performed. In this case, the second deterioration preliminary determination (2) is made.
Next, in step S7, it is determined whether or not the integrated value driven at an engine speed equal to or higher than a predetermined speed reaches a predetermined value. If the integrated value exceeds a predetermined time, a deterioration preliminary determination is performed. In this case, a third deterioration preliminary determination (3) is made.
As described above, when the deterioration preliminary determination is performed three or more times in step S5 to step S7, the failure determination of the catalyst 23 is performed.

If the time at which the exhaust temperature exceeds a certain temperature in step S5 is within a predetermined time, it is determined in step S8 whether or not the integrated value of the exhaust gas rich state reaches a predetermined value. If yes, a preliminary deterioration judgment is performed. In this case, the first deterioration preliminary determination (1) is made.
Next, in step S9, it is determined whether or not the integrated value driven at an engine speed equal to or higher than a predetermined speed reaches a predetermined value. If the predetermined value has exceeded a predetermined time, a deterioration preliminary determination is performed. In this case, the second deterioration preliminary determination (2) is made.
As described above, when the deterioration preliminary determination is performed twice in steps S8 to S9, the failure determination of the catalyst 23 is not performed.

  When the deterioration preliminary determination is performed three times or more as in step S4 or step S7, a signal related to the failure determination is sent from the catalyst deterioration determination unit 3 to the catalyst deterioration state notification unit 4. The catalyst deterioration state informing unit 4 notifies the deterioration state of the catalyst 23, that is, the failure determination by an appropriate lamp or display in the meter 113 (see FIG. 1), and the rider of the motorcycle 100 can know the deterioration state of the catalyst 23. .

  According to the present invention, the high temperature state of the catalyst 23 is estimated using various parameters of the state of the exhaust gas, and the history of the catalyst 23 is continuously acquired and checked, so that the deterioration state of the catalyst 23 is accurately known. be able to. In this case, the exhaust gas temperature sensor 25 and the oxygen concentration sensor 26 are not provided on the downstream side of the catalyst 23, that is, the exhaust gas temperature sensor 25 and the oxygen concentration sensor 26 are provided only on the upstream side of the catalyst 23, thereby simplifying the catalyst deterioration determination device. Can be configured.

  Since the exhaust temperature sensor 25 and the oxygen concentration sensor 26 are not provided on the downstream side of the catalyst 23, they do not protrude from the muffler 12, and the muffler 12 does not protrude to the peripheral parts, so that component layout is improved. . Further, since the exhaust temperature sensor 25 and the oxygen concentration sensor 26 are not exposed around the rear end portion of the muffler, it is possible to eliminate the influence on the appearance including those wirings and improve the appearance.

Here, in the modification of the present invention, in the above embodiment, the failure determination of the catalyst 23 is performed when the deterioration preliminary determination is performed three times or more, but any two or more of the plurality of deterioration preliminary determinations are performed. In this case, the failure determination of the catalyst 23 may be performed. For example, the failure determination of the catalyst 23 is performed when the two deterioration preliminary determinations of the first deterioration preliminary determination in step S2 and the second deterioration preliminary determination in step S3 are performed.
Even in this case, as in the above-described embodiment, if the exhaust temperature exceeds the limit temperature (for example, 1000 ° C.) even once, failure determination is performed.

As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
The exhaust temperature sensor 25 and the oxygen concentration sensor 26 in the above embodiment may be arranged on the upstream side and the downstream side of the exhaust gas in a reverse relationship to the above.
Also, in the above embodiment, the exhaust gas exhaust temperature, oxygen concentration, and specific values such as the vehicle mileage have been explained, but these values can be appropriately changed according to the type of vehicle or engine type. However, the present invention is not limited to the numerical values according to the present embodiment.
Further, although the example in which the present invention is applied to the motorcycle 100 has been described, the present invention can be effectively applied to internal combustion engines of various types including other vehicles.

1 engine unit, 1A engine, 1B engine speed sensor, 2 ECU, 3 catalyst deterioration determination unit, 4 catalyst deterioration state notification unit, 10 exhaust system, 11 exhaust pipe, 12 muffler, 14 outer cylinder, 15 inner cylinder, 20 front pipe 21 center pipe, 22 tailpiece, 23 catalyst, 25 exhaust temperature sensor, 26 oxygen concentration sensor, 100 motorcycle.

Claims (8)

In an exhaust system of an engine in which a catalyst is mounted in the middle part of the muffler, an exhaust temperature sensor and an oxygen concentration sensor are provided only on the upstream side of the catalyst,
An exhaust system catalyst deterioration determination device, wherein a deterioration state of the catalyst is determined based on detection signals of the exhaust temperature sensor and the oxygen concentration sensor. In an engine exhaust system in which an exhaust temperature sensor and an oxygen concentration sensor are provided on the upstream side of the catalyst attached to the middle part of the muffler,
The deterioration state of the catalyst is determined using any one of an exhaust temperature upstream of the catalyst, an oxygen concentration, an engine speed of the engine, and a cumulative travel distance of a vehicle on which the engine is mounted. To determine the catalyst deterioration of the exhaust system.   The exhaust system catalyst deterioration determination method according to claim 2, wherein the catalyst failure determination is performed when the exhaust temperature exceeds a limit temperature related to the catalyst.   Preliminary deterioration determination of the catalyst is performed based on the exhaust temperature, the oxygen concentration, the engine speed, and the cumulative travel distance, and the failure determination of the catalyst is performed when any of the plurality of deterioration preliminary determinations is made. The method for determining catalyst deterioration in an exhaust system according to claim 2.   5. The exhaust system catalyst deterioration determination method according to claim 4, wherein preliminary deterioration determination of the catalyst is performed when the accumulated travel distance exceeds a predetermined value.   5. The exhaust system catalyst according to claim 4, wherein a preliminary deterioration determination of the catalyst is performed when the cumulative number of continuous travels for a certain period of time at a temperature equal to or higher than a predetermined first temperature exceeds a predetermined number. Degradation judgment method.   5. The exhaust system catalyst deterioration according to claim 4, wherein the catalyst deterioration preliminary determination is performed when the cumulative number of times of continuous running for a predetermined time during the rich state determination by the oxygen concentration sensor exceeds a predetermined number. Judgment method.   The exhaust system catalyst according to claim 4, wherein the catalyst deterioration preliminary determination is performed when the cumulative number of continuous runnings for a predetermined time at an engine speed equal to or higher than a predetermined speed exceeds a predetermined number. Degradation judgment method.

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